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- // SPDX-License-Identifier: GPL-2.0-only
- /* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
- * Copyright (c) 2016 Facebook
- * Copyright (c) 2018 Covalent IO, Inc. http://covalent.io
- */
- #include <uapi/linux/btf.h>
- #include <linux/kernel.h>
- #include <linux/types.h>
- #include <linux/slab.h>
- #include <linux/bpf.h>
- #include <linux/btf.h>
- #include <linux/bpf_verifier.h>
- #include <linux/filter.h>
- #include <net/netlink.h>
- #include <linux/file.h>
- #include <linux/vmalloc.h>
- #include <linux/stringify.h>
- #include <linux/bsearch.h>
- #include <linux/sort.h>
- #include <linux/perf_event.h>
- #include <linux/ctype.h>
- #include <linux/error-injection.h>
- #include <linux/bpf_lsm.h>
- #include <linux/btf_ids.h>
- #include "disasm.h"
- static const struct bpf_verifier_ops * const bpf_verifier_ops[] = {
- #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
- [_id] = & _name ## _verifier_ops,
- #define BPF_MAP_TYPE(_id, _ops)
- #define BPF_LINK_TYPE(_id, _name)
- #include <linux/bpf_types.h>
- #undef BPF_PROG_TYPE
- #undef BPF_MAP_TYPE
- #undef BPF_LINK_TYPE
- };
- /* bpf_check() is a static code analyzer that walks eBPF program
- * instruction by instruction and updates register/stack state.
- * All paths of conditional branches are analyzed until 'bpf_exit' insn.
- *
- * The first pass is depth-first-search to check that the program is a DAG.
- * It rejects the following programs:
- * - larger than BPF_MAXINSNS insns
- * - if loop is present (detected via back-edge)
- * - unreachable insns exist (shouldn't be a forest. program = one function)
- * - out of bounds or malformed jumps
- * The second pass is all possible path descent from the 1st insn.
- * Since it's analyzing all pathes through the program, the length of the
- * analysis is limited to 64k insn, which may be hit even if total number of
- * insn is less then 4K, but there are too many branches that change stack/regs.
- * Number of 'branches to be analyzed' is limited to 1k
- *
- * On entry to each instruction, each register has a type, and the instruction
- * changes the types of the registers depending on instruction semantics.
- * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
- * copied to R1.
- *
- * All registers are 64-bit.
- * R0 - return register
- * R1-R5 argument passing registers
- * R6-R9 callee saved registers
- * R10 - frame pointer read-only
- *
- * At the start of BPF program the register R1 contains a pointer to bpf_context
- * and has type PTR_TO_CTX.
- *
- * Verifier tracks arithmetic operations on pointers in case:
- * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
- * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
- * 1st insn copies R10 (which has FRAME_PTR) type into R1
- * and 2nd arithmetic instruction is pattern matched to recognize
- * that it wants to construct a pointer to some element within stack.
- * So after 2nd insn, the register R1 has type PTR_TO_STACK
- * (and -20 constant is saved for further stack bounds checking).
- * Meaning that this reg is a pointer to stack plus known immediate constant.
- *
- * Most of the time the registers have SCALAR_VALUE type, which
- * means the register has some value, but it's not a valid pointer.
- * (like pointer plus pointer becomes SCALAR_VALUE type)
- *
- * When verifier sees load or store instructions the type of base register
- * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, PTR_TO_STACK, PTR_TO_SOCKET. These are
- * four pointer types recognized by check_mem_access() function.
- *
- * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
- * and the range of [ptr, ptr + map's value_size) is accessible.
- *
- * registers used to pass values to function calls are checked against
- * function argument constraints.
- *
- * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
- * It means that the register type passed to this function must be
- * PTR_TO_STACK and it will be used inside the function as
- * 'pointer to map element key'
- *
- * For example the argument constraints for bpf_map_lookup_elem():
- * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
- * .arg1_type = ARG_CONST_MAP_PTR,
- * .arg2_type = ARG_PTR_TO_MAP_KEY,
- *
- * ret_type says that this function returns 'pointer to map elem value or null'
- * function expects 1st argument to be a const pointer to 'struct bpf_map' and
- * 2nd argument should be a pointer to stack, which will be used inside
- * the helper function as a pointer to map element key.
- *
- * On the kernel side the helper function looks like:
- * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
- * {
- * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
- * void *key = (void *) (unsigned long) r2;
- * void *value;
- *
- * here kernel can access 'key' and 'map' pointers safely, knowing that
- * [key, key + map->key_size) bytes are valid and were initialized on
- * the stack of eBPF program.
- * }
- *
- * Corresponding eBPF program may look like:
- * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR
- * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
- * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP
- * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
- * here verifier looks at prototype of map_lookup_elem() and sees:
- * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
- * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
- *
- * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
- * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
- * and were initialized prior to this call.
- * If it's ok, then verifier allows this BPF_CALL insn and looks at
- * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
- * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
- * returns ether pointer to map value or NULL.
- *
- * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
- * insn, the register holding that pointer in the true branch changes state to
- * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
- * branch. See check_cond_jmp_op().
- *
- * After the call R0 is set to return type of the function and registers R1-R5
- * are set to NOT_INIT to indicate that they are no longer readable.
- *
- * The following reference types represent a potential reference to a kernel
- * resource which, after first being allocated, must be checked and freed by
- * the BPF program:
- * - PTR_TO_SOCKET_OR_NULL, PTR_TO_SOCKET
- *
- * When the verifier sees a helper call return a reference type, it allocates a
- * pointer id for the reference and stores it in the current function state.
- * Similar to the way that PTR_TO_MAP_VALUE_OR_NULL is converted into
- * PTR_TO_MAP_VALUE, PTR_TO_SOCKET_OR_NULL becomes PTR_TO_SOCKET when the type
- * passes through a NULL-check conditional. For the branch wherein the state is
- * changed to CONST_IMM, the verifier releases the reference.
- *
- * For each helper function that allocates a reference, such as
- * bpf_sk_lookup_tcp(), there is a corresponding release function, such as
- * bpf_sk_release(). When a reference type passes into the release function,
- * the verifier also releases the reference. If any unchecked or unreleased
- * reference remains at the end of the program, the verifier rejects it.
- */
- /* verifier_state + insn_idx are pushed to stack when branch is encountered */
- struct bpf_verifier_stack_elem {
- /* verifer state is 'st'
- * before processing instruction 'insn_idx'
- * and after processing instruction 'prev_insn_idx'
- */
- struct bpf_verifier_state st;
- int insn_idx;
- int prev_insn_idx;
- struct bpf_verifier_stack_elem *next;
- /* length of verifier log at the time this state was pushed on stack */
- u32 log_pos;
- };
- #define BPF_COMPLEXITY_LIMIT_JMP_SEQ 8192
- #define BPF_COMPLEXITY_LIMIT_STATES 64
- #define BPF_MAP_KEY_POISON (1ULL << 63)
- #define BPF_MAP_KEY_SEEN (1ULL << 62)
- #define BPF_MAP_PTR_UNPRIV 1UL
- #define BPF_MAP_PTR_POISON ((void *)((0xeB9FUL << 1) + \
- POISON_POINTER_DELTA))
- #define BPF_MAP_PTR(X) ((struct bpf_map *)((X) & ~BPF_MAP_PTR_UNPRIV))
- static bool bpf_map_ptr_poisoned(const struct bpf_insn_aux_data *aux)
- {
- return BPF_MAP_PTR(aux->map_ptr_state) == BPF_MAP_PTR_POISON;
- }
- static bool bpf_map_ptr_unpriv(const struct bpf_insn_aux_data *aux)
- {
- return aux->map_ptr_state & BPF_MAP_PTR_UNPRIV;
- }
- static void bpf_map_ptr_store(struct bpf_insn_aux_data *aux,
- const struct bpf_map *map, bool unpriv)
- {
- BUILD_BUG_ON((unsigned long)BPF_MAP_PTR_POISON & BPF_MAP_PTR_UNPRIV);
- unpriv |= bpf_map_ptr_unpriv(aux);
- aux->map_ptr_state = (unsigned long)map |
- (unpriv ? BPF_MAP_PTR_UNPRIV : 0UL);
- }
- static bool bpf_map_key_poisoned(const struct bpf_insn_aux_data *aux)
- {
- return aux->map_key_state & BPF_MAP_KEY_POISON;
- }
- static bool bpf_map_key_unseen(const struct bpf_insn_aux_data *aux)
- {
- return !(aux->map_key_state & BPF_MAP_KEY_SEEN);
- }
- static u64 bpf_map_key_immediate(const struct bpf_insn_aux_data *aux)
- {
- return aux->map_key_state & ~(BPF_MAP_KEY_SEEN | BPF_MAP_KEY_POISON);
- }
- static void bpf_map_key_store(struct bpf_insn_aux_data *aux, u64 state)
- {
- bool poisoned = bpf_map_key_poisoned(aux);
- aux->map_key_state = state | BPF_MAP_KEY_SEEN |
- (poisoned ? BPF_MAP_KEY_POISON : 0ULL);
- }
- struct bpf_call_arg_meta {
- struct bpf_map *map_ptr;
- bool raw_mode;
- bool pkt_access;
- int regno;
- int access_size;
- int mem_size;
- u64 msize_max_value;
- int ref_obj_id;
- int func_id;
- u32 btf_id;
- u32 ret_btf_id;
- };
- struct btf *btf_vmlinux;
- static DEFINE_MUTEX(bpf_verifier_lock);
- static const struct bpf_line_info *
- find_linfo(const struct bpf_verifier_env *env, u32 insn_off)
- {
- const struct bpf_line_info *linfo;
- const struct bpf_prog *prog;
- u32 i, nr_linfo;
- prog = env->prog;
- nr_linfo = prog->aux->nr_linfo;
- if (!nr_linfo || insn_off >= prog->len)
- return NULL;
- linfo = prog->aux->linfo;
- for (i = 1; i < nr_linfo; i++)
- if (insn_off < linfo[i].insn_off)
- break;
- return &linfo[i - 1];
- }
- void bpf_verifier_vlog(struct bpf_verifier_log *log, const char *fmt,
- va_list args)
- {
- unsigned int n;
- n = vscnprintf(log->kbuf, BPF_VERIFIER_TMP_LOG_SIZE, fmt, args);
- WARN_ONCE(n >= BPF_VERIFIER_TMP_LOG_SIZE - 1,
- "verifier log line truncated - local buffer too short\n");
- n = min(log->len_total - log->len_used - 1, n);
- log->kbuf[n] = '\0';
- if (log->level == BPF_LOG_KERNEL) {
- pr_err("BPF:%s\n", log->kbuf);
- return;
- }
- if (!copy_to_user(log->ubuf + log->len_used, log->kbuf, n + 1))
- log->len_used += n;
- else
- log->ubuf = NULL;
- }
- static void bpf_vlog_reset(struct bpf_verifier_log *log, u32 new_pos)
- {
- char zero = 0;
- if (!bpf_verifier_log_needed(log))
- return;
- log->len_used = new_pos;
- if (put_user(zero, log->ubuf + new_pos))
- log->ubuf = NULL;
- }
- /* log_level controls verbosity level of eBPF verifier.
- * bpf_verifier_log_write() is used to dump the verification trace to the log,
- * so the user can figure out what's wrong with the program
- */
- __printf(2, 3) void bpf_verifier_log_write(struct bpf_verifier_env *env,
- const char *fmt, ...)
- {
- va_list args;
- if (!bpf_verifier_log_needed(&env->log))
- return;
- va_start(args, fmt);
- bpf_verifier_vlog(&env->log, fmt, args);
- va_end(args);
- }
- EXPORT_SYMBOL_GPL(bpf_verifier_log_write);
- __printf(2, 3) static void verbose(void *private_data, const char *fmt, ...)
- {
- struct bpf_verifier_env *env = private_data;
- va_list args;
- if (!bpf_verifier_log_needed(&env->log))
- return;
- va_start(args, fmt);
- bpf_verifier_vlog(&env->log, fmt, args);
- va_end(args);
- }
- __printf(2, 3) void bpf_log(struct bpf_verifier_log *log,
- const char *fmt, ...)
- {
- va_list args;
- if (!bpf_verifier_log_needed(log))
- return;
- va_start(args, fmt);
- bpf_verifier_vlog(log, fmt, args);
- va_end(args);
- }
- static const char *ltrim(const char *s)
- {
- while (isspace(*s))
- s++;
- return s;
- }
- __printf(3, 4) static void verbose_linfo(struct bpf_verifier_env *env,
- u32 insn_off,
- const char *prefix_fmt, ...)
- {
- const struct bpf_line_info *linfo;
- if (!bpf_verifier_log_needed(&env->log))
- return;
- linfo = find_linfo(env, insn_off);
- if (!linfo || linfo == env->prev_linfo)
- return;
- if (prefix_fmt) {
- va_list args;
- va_start(args, prefix_fmt);
- bpf_verifier_vlog(&env->log, prefix_fmt, args);
- va_end(args);
- }
- verbose(env, "%s\n",
- ltrim(btf_name_by_offset(env->prog->aux->btf,
- linfo->line_off)));
- env->prev_linfo = linfo;
- }
- static bool type_is_pkt_pointer(enum bpf_reg_type type)
- {
- return type == PTR_TO_PACKET ||
- type == PTR_TO_PACKET_META;
- }
- static bool type_is_sk_pointer(enum bpf_reg_type type)
- {
- return type == PTR_TO_SOCKET ||
- type == PTR_TO_SOCK_COMMON ||
- type == PTR_TO_TCP_SOCK ||
- type == PTR_TO_XDP_SOCK;
- }
- static bool reg_type_not_null(enum bpf_reg_type type)
- {
- return type == PTR_TO_SOCKET ||
- type == PTR_TO_TCP_SOCK ||
- type == PTR_TO_MAP_VALUE ||
- type == PTR_TO_SOCK_COMMON;
- }
- static bool reg_type_may_be_null(enum bpf_reg_type type)
- {
- return type == PTR_TO_MAP_VALUE_OR_NULL ||
- type == PTR_TO_SOCKET_OR_NULL ||
- type == PTR_TO_SOCK_COMMON_OR_NULL ||
- type == PTR_TO_TCP_SOCK_OR_NULL ||
- type == PTR_TO_BTF_ID_OR_NULL ||
- type == PTR_TO_MEM_OR_NULL ||
- type == PTR_TO_RDONLY_BUF_OR_NULL ||
- type == PTR_TO_RDWR_BUF_OR_NULL;
- }
- static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
- {
- return reg->type == PTR_TO_MAP_VALUE &&
- map_value_has_spin_lock(reg->map_ptr);
- }
- static bool reg_type_may_be_refcounted_or_null(enum bpf_reg_type type)
- {
- return type == PTR_TO_SOCKET ||
- type == PTR_TO_SOCKET_OR_NULL ||
- type == PTR_TO_TCP_SOCK ||
- type == PTR_TO_TCP_SOCK_OR_NULL ||
- type == PTR_TO_MEM ||
- type == PTR_TO_MEM_OR_NULL;
- }
- static bool arg_type_may_be_refcounted(enum bpf_arg_type type)
- {
- return type == ARG_PTR_TO_SOCK_COMMON;
- }
- static bool arg_type_may_be_null(enum bpf_arg_type type)
- {
- return type == ARG_PTR_TO_MAP_VALUE_OR_NULL ||
- type == ARG_PTR_TO_MEM_OR_NULL ||
- type == ARG_PTR_TO_CTX_OR_NULL ||
- type == ARG_PTR_TO_SOCKET_OR_NULL ||
- type == ARG_PTR_TO_ALLOC_MEM_OR_NULL;
- }
- /* Determine whether the function releases some resources allocated by another
- * function call. The first reference type argument will be assumed to be
- * released by release_reference().
- */
- static bool is_release_function(enum bpf_func_id func_id)
- {
- return func_id == BPF_FUNC_sk_release ||
- func_id == BPF_FUNC_ringbuf_submit ||
- func_id == BPF_FUNC_ringbuf_discard;
- }
- static bool may_be_acquire_function(enum bpf_func_id func_id)
- {
- return func_id == BPF_FUNC_sk_lookup_tcp ||
- func_id == BPF_FUNC_sk_lookup_udp ||
- func_id == BPF_FUNC_skc_lookup_tcp ||
- func_id == BPF_FUNC_map_lookup_elem ||
- func_id == BPF_FUNC_ringbuf_reserve;
- }
- static bool is_acquire_function(enum bpf_func_id func_id,
- const struct bpf_map *map)
- {
- enum bpf_map_type map_type = map ? map->map_type : BPF_MAP_TYPE_UNSPEC;
- if (func_id == BPF_FUNC_sk_lookup_tcp ||
- func_id == BPF_FUNC_sk_lookup_udp ||
- func_id == BPF_FUNC_skc_lookup_tcp ||
- func_id == BPF_FUNC_ringbuf_reserve)
- return true;
- if (func_id == BPF_FUNC_map_lookup_elem &&
- (map_type == BPF_MAP_TYPE_SOCKMAP ||
- map_type == BPF_MAP_TYPE_SOCKHASH))
- return true;
- return false;
- }
- static bool is_ptr_cast_function(enum bpf_func_id func_id)
- {
- return func_id == BPF_FUNC_tcp_sock ||
- func_id == BPF_FUNC_sk_fullsock ||
- func_id == BPF_FUNC_skc_to_tcp_sock ||
- func_id == BPF_FUNC_skc_to_tcp6_sock ||
- func_id == BPF_FUNC_skc_to_udp6_sock ||
- func_id == BPF_FUNC_skc_to_tcp_timewait_sock ||
- func_id == BPF_FUNC_skc_to_tcp_request_sock;
- }
- /* string representation of 'enum bpf_reg_type' */
- static const char * const reg_type_str[] = {
- [NOT_INIT] = "?",
- [SCALAR_VALUE] = "inv",
- [PTR_TO_CTX] = "ctx",
- [CONST_PTR_TO_MAP] = "map_ptr",
- [PTR_TO_MAP_VALUE] = "map_value",
- [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null",
- [PTR_TO_STACK] = "fp",
- [PTR_TO_PACKET] = "pkt",
- [PTR_TO_PACKET_META] = "pkt_meta",
- [PTR_TO_PACKET_END] = "pkt_end",
- [PTR_TO_FLOW_KEYS] = "flow_keys",
- [PTR_TO_SOCKET] = "sock",
- [PTR_TO_SOCKET_OR_NULL] = "sock_or_null",
- [PTR_TO_SOCK_COMMON] = "sock_common",
- [PTR_TO_SOCK_COMMON_OR_NULL] = "sock_common_or_null",
- [PTR_TO_TCP_SOCK] = "tcp_sock",
- [PTR_TO_TCP_SOCK_OR_NULL] = "tcp_sock_or_null",
- [PTR_TO_TP_BUFFER] = "tp_buffer",
- [PTR_TO_XDP_SOCK] = "xdp_sock",
- [PTR_TO_BTF_ID] = "ptr_",
- [PTR_TO_BTF_ID_OR_NULL] = "ptr_or_null_",
- [PTR_TO_PERCPU_BTF_ID] = "percpu_ptr_",
- [PTR_TO_MEM] = "mem",
- [PTR_TO_MEM_OR_NULL] = "mem_or_null",
- [PTR_TO_RDONLY_BUF] = "rdonly_buf",
- [PTR_TO_RDONLY_BUF_OR_NULL] = "rdonly_buf_or_null",
- [PTR_TO_RDWR_BUF] = "rdwr_buf",
- [PTR_TO_RDWR_BUF_OR_NULL] = "rdwr_buf_or_null",
- };
- static char slot_type_char[] = {
- [STACK_INVALID] = '?',
- [STACK_SPILL] = 'r',
- [STACK_MISC] = 'm',
- [STACK_ZERO] = '0',
- };
- static void print_liveness(struct bpf_verifier_env *env,
- enum bpf_reg_liveness live)
- {
- if (live & (REG_LIVE_READ | REG_LIVE_WRITTEN | REG_LIVE_DONE))
- verbose(env, "_");
- if (live & REG_LIVE_READ)
- verbose(env, "r");
- if (live & REG_LIVE_WRITTEN)
- verbose(env, "w");
- if (live & REG_LIVE_DONE)
- verbose(env, "D");
- }
- static struct bpf_func_state *func(struct bpf_verifier_env *env,
- const struct bpf_reg_state *reg)
- {
- struct bpf_verifier_state *cur = env->cur_state;
- return cur->frame[reg->frameno];
- }
- const char *kernel_type_name(u32 id)
- {
- return btf_name_by_offset(btf_vmlinux,
- btf_type_by_id(btf_vmlinux, id)->name_off);
- }
- static void print_verifier_state(struct bpf_verifier_env *env,
- const struct bpf_func_state *state)
- {
- const struct bpf_reg_state *reg;
- enum bpf_reg_type t;
- int i;
- if (state->frameno)
- verbose(env, " frame%d:", state->frameno);
- for (i = 0; i < MAX_BPF_REG; i++) {
- reg = &state->regs[i];
- t = reg->type;
- if (t == NOT_INIT)
- continue;
- verbose(env, " R%d", i);
- print_liveness(env, reg->live);
- verbose(env, "=%s", reg_type_str[t]);
- if (t == SCALAR_VALUE && reg->precise)
- verbose(env, "P");
- if ((t == SCALAR_VALUE || t == PTR_TO_STACK) &&
- tnum_is_const(reg->var_off)) {
- /* reg->off should be 0 for SCALAR_VALUE */
- verbose(env, "%lld", reg->var_off.value + reg->off);
- } else {
- if (t == PTR_TO_BTF_ID ||
- t == PTR_TO_BTF_ID_OR_NULL ||
- t == PTR_TO_PERCPU_BTF_ID)
- verbose(env, "%s", kernel_type_name(reg->btf_id));
- verbose(env, "(id=%d", reg->id);
- if (reg_type_may_be_refcounted_or_null(t))
- verbose(env, ",ref_obj_id=%d", reg->ref_obj_id);
- if (t != SCALAR_VALUE)
- verbose(env, ",off=%d", reg->off);
- if (type_is_pkt_pointer(t))
- verbose(env, ",r=%d", reg->range);
- else if (t == CONST_PTR_TO_MAP ||
- t == PTR_TO_MAP_VALUE ||
- t == PTR_TO_MAP_VALUE_OR_NULL)
- verbose(env, ",ks=%d,vs=%d",
- reg->map_ptr->key_size,
- reg->map_ptr->value_size);
- if (tnum_is_const(reg->var_off)) {
- /* Typically an immediate SCALAR_VALUE, but
- * could be a pointer whose offset is too big
- * for reg->off
- */
- verbose(env, ",imm=%llx", reg->var_off.value);
- } else {
- if (reg->smin_value != reg->umin_value &&
- reg->smin_value != S64_MIN)
- verbose(env, ",smin_value=%lld",
- (long long)reg->smin_value);
- if (reg->smax_value != reg->umax_value &&
- reg->smax_value != S64_MAX)
- verbose(env, ",smax_value=%lld",
- (long long)reg->smax_value);
- if (reg->umin_value != 0)
- verbose(env, ",umin_value=%llu",
- (unsigned long long)reg->umin_value);
- if (reg->umax_value != U64_MAX)
- verbose(env, ",umax_value=%llu",
- (unsigned long long)reg->umax_value);
- if (!tnum_is_unknown(reg->var_off)) {
- char tn_buf[48];
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env, ",var_off=%s", tn_buf);
- }
- if (reg->s32_min_value != reg->smin_value &&
- reg->s32_min_value != S32_MIN)
- verbose(env, ",s32_min_value=%d",
- (int)(reg->s32_min_value));
- if (reg->s32_max_value != reg->smax_value &&
- reg->s32_max_value != S32_MAX)
- verbose(env, ",s32_max_value=%d",
- (int)(reg->s32_max_value));
- if (reg->u32_min_value != reg->umin_value &&
- reg->u32_min_value != U32_MIN)
- verbose(env, ",u32_min_value=%d",
- (int)(reg->u32_min_value));
- if (reg->u32_max_value != reg->umax_value &&
- reg->u32_max_value != U32_MAX)
- verbose(env, ",u32_max_value=%d",
- (int)(reg->u32_max_value));
- }
- verbose(env, ")");
- }
- }
- for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
- char types_buf[BPF_REG_SIZE + 1];
- bool valid = false;
- int j;
- for (j = 0; j < BPF_REG_SIZE; j++) {
- if (state->stack[i].slot_type[j] != STACK_INVALID)
- valid = true;
- types_buf[j] = slot_type_char[
- state->stack[i].slot_type[j]];
- }
- types_buf[BPF_REG_SIZE] = 0;
- if (!valid)
- continue;
- verbose(env, " fp%d", (-i - 1) * BPF_REG_SIZE);
- print_liveness(env, state->stack[i].spilled_ptr.live);
- if (state->stack[i].slot_type[0] == STACK_SPILL) {
- reg = &state->stack[i].spilled_ptr;
- t = reg->type;
- verbose(env, "=%s", reg_type_str[t]);
- if (t == SCALAR_VALUE && reg->precise)
- verbose(env, "P");
- if (t == SCALAR_VALUE && tnum_is_const(reg->var_off))
- verbose(env, "%lld", reg->var_off.value + reg->off);
- } else {
- verbose(env, "=%s", types_buf);
- }
- }
- if (state->acquired_refs && state->refs[0].id) {
- verbose(env, " refs=%d", state->refs[0].id);
- for (i = 1; i < state->acquired_refs; i++)
- if (state->refs[i].id)
- verbose(env, ",%d", state->refs[i].id);
- }
- verbose(env, "\n");
- }
- #define COPY_STATE_FN(NAME, COUNT, FIELD, SIZE) \
- static int copy_##NAME##_state(struct bpf_func_state *dst, \
- const struct bpf_func_state *src) \
- { \
- if (!src->FIELD) \
- return 0; \
- if (WARN_ON_ONCE(dst->COUNT < src->COUNT)) { \
- /* internal bug, make state invalid to reject the program */ \
- memset(dst, 0, sizeof(*dst)); \
- return -EFAULT; \
- } \
- memcpy(dst->FIELD, src->FIELD, \
- sizeof(*src->FIELD) * (src->COUNT / SIZE)); \
- return 0; \
- }
- /* copy_reference_state() */
- COPY_STATE_FN(reference, acquired_refs, refs, 1)
- /* copy_stack_state() */
- COPY_STATE_FN(stack, allocated_stack, stack, BPF_REG_SIZE)
- #undef COPY_STATE_FN
- #define REALLOC_STATE_FN(NAME, COUNT, FIELD, SIZE) \
- static int realloc_##NAME##_state(struct bpf_func_state *state, int size, \
- bool copy_old) \
- { \
- u32 old_size = state->COUNT; \
- struct bpf_##NAME##_state *new_##FIELD; \
- int slot = size / SIZE; \
- \
- if (size <= old_size || !size) { \
- if (copy_old) \
- return 0; \
- state->COUNT = slot * SIZE; \
- if (!size && old_size) { \
- kfree(state->FIELD); \
- state->FIELD = NULL; \
- } \
- return 0; \
- } \
- new_##FIELD = kmalloc_array(slot, sizeof(struct bpf_##NAME##_state), \
- GFP_KERNEL); \
- if (!new_##FIELD) \
- return -ENOMEM; \
- if (copy_old) { \
- if (state->FIELD) \
- memcpy(new_##FIELD, state->FIELD, \
- sizeof(*new_##FIELD) * (old_size / SIZE)); \
- memset(new_##FIELD + old_size / SIZE, 0, \
- sizeof(*new_##FIELD) * (size - old_size) / SIZE); \
- } \
- state->COUNT = slot * SIZE; \
- kfree(state->FIELD); \
- state->FIELD = new_##FIELD; \
- return 0; \
- }
- /* realloc_reference_state() */
- REALLOC_STATE_FN(reference, acquired_refs, refs, 1)
- /* realloc_stack_state() */
- REALLOC_STATE_FN(stack, allocated_stack, stack, BPF_REG_SIZE)
- #undef REALLOC_STATE_FN
- /* do_check() starts with zero-sized stack in struct bpf_verifier_state to
- * make it consume minimal amount of memory. check_stack_write() access from
- * the program calls into realloc_func_state() to grow the stack size.
- * Note there is a non-zero 'parent' pointer inside bpf_verifier_state
- * which realloc_stack_state() copies over. It points to previous
- * bpf_verifier_state which is never reallocated.
- */
- static int realloc_func_state(struct bpf_func_state *state, int stack_size,
- int refs_size, bool copy_old)
- {
- int err = realloc_reference_state(state, refs_size, copy_old);
- if (err)
- return err;
- return realloc_stack_state(state, stack_size, copy_old);
- }
- /* Acquire a pointer id from the env and update the state->refs to include
- * this new pointer reference.
- * On success, returns a valid pointer id to associate with the register
- * On failure, returns a negative errno.
- */
- static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx)
- {
- struct bpf_func_state *state = cur_func(env);
- int new_ofs = state->acquired_refs;
- int id, err;
- err = realloc_reference_state(state, state->acquired_refs + 1, true);
- if (err)
- return err;
- id = ++env->id_gen;
- state->refs[new_ofs].id = id;
- state->refs[new_ofs].insn_idx = insn_idx;
- return id;
- }
- /* release function corresponding to acquire_reference_state(). Idempotent. */
- static int release_reference_state(struct bpf_func_state *state, int ptr_id)
- {
- int i, last_idx;
- last_idx = state->acquired_refs - 1;
- for (i = 0; i < state->acquired_refs; i++) {
- if (state->refs[i].id == ptr_id) {
- if (last_idx && i != last_idx)
- memcpy(&state->refs[i], &state->refs[last_idx],
- sizeof(*state->refs));
- memset(&state->refs[last_idx], 0, sizeof(*state->refs));
- state->acquired_refs--;
- return 0;
- }
- }
- return -EINVAL;
- }
- static int transfer_reference_state(struct bpf_func_state *dst,
- struct bpf_func_state *src)
- {
- int err = realloc_reference_state(dst, src->acquired_refs, false);
- if (err)
- return err;
- err = copy_reference_state(dst, src);
- if (err)
- return err;
- return 0;
- }
- static void free_func_state(struct bpf_func_state *state)
- {
- if (!state)
- return;
- kfree(state->refs);
- kfree(state->stack);
- kfree(state);
- }
- static void clear_jmp_history(struct bpf_verifier_state *state)
- {
- kfree(state->jmp_history);
- state->jmp_history = NULL;
- state->jmp_history_cnt = 0;
- }
- static void free_verifier_state(struct bpf_verifier_state *state,
- bool free_self)
- {
- int i;
- for (i = 0; i <= state->curframe; i++) {
- free_func_state(state->frame[i]);
- state->frame[i] = NULL;
- }
- clear_jmp_history(state);
- if (free_self)
- kfree(state);
- }
- /* copy verifier state from src to dst growing dst stack space
- * when necessary to accommodate larger src stack
- */
- static int copy_func_state(struct bpf_func_state *dst,
- const struct bpf_func_state *src)
- {
- int err;
- err = realloc_func_state(dst, src->allocated_stack, src->acquired_refs,
- false);
- if (err)
- return err;
- memcpy(dst, src, offsetof(struct bpf_func_state, acquired_refs));
- err = copy_reference_state(dst, src);
- if (err)
- return err;
- return copy_stack_state(dst, src);
- }
- static int copy_verifier_state(struct bpf_verifier_state *dst_state,
- const struct bpf_verifier_state *src)
- {
- struct bpf_func_state *dst;
- u32 jmp_sz = sizeof(struct bpf_idx_pair) * src->jmp_history_cnt;
- int i, err;
- if (dst_state->jmp_history_cnt < src->jmp_history_cnt) {
- kfree(dst_state->jmp_history);
- dst_state->jmp_history = kmalloc(jmp_sz, GFP_USER);
- if (!dst_state->jmp_history)
- return -ENOMEM;
- }
- memcpy(dst_state->jmp_history, src->jmp_history, jmp_sz);
- dst_state->jmp_history_cnt = src->jmp_history_cnt;
- /* if dst has more stack frames then src frame, free them */
- for (i = src->curframe + 1; i <= dst_state->curframe; i++) {
- free_func_state(dst_state->frame[i]);
- dst_state->frame[i] = NULL;
- }
- dst_state->speculative = src->speculative;
- dst_state->curframe = src->curframe;
- dst_state->active_spin_lock = src->active_spin_lock;
- dst_state->branches = src->branches;
- dst_state->parent = src->parent;
- dst_state->first_insn_idx = src->first_insn_idx;
- dst_state->last_insn_idx = src->last_insn_idx;
- for (i = 0; i <= src->curframe; i++) {
- dst = dst_state->frame[i];
- if (!dst) {
- dst = kzalloc(sizeof(*dst), GFP_KERNEL);
- if (!dst)
- return -ENOMEM;
- dst_state->frame[i] = dst;
- }
- err = copy_func_state(dst, src->frame[i]);
- if (err)
- return err;
- }
- return 0;
- }
- static void update_branch_counts(struct bpf_verifier_env *env, struct bpf_verifier_state *st)
- {
- while (st) {
- u32 br = --st->branches;
- /* WARN_ON(br > 1) technically makes sense here,
- * but see comment in push_stack(), hence:
- */
- WARN_ONCE((int)br < 0,
- "BUG update_branch_counts:branches_to_explore=%d\n",
- br);
- if (br)
- break;
- st = st->parent;
- }
- }
- static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx,
- int *insn_idx, bool pop_log)
- {
- struct bpf_verifier_state *cur = env->cur_state;
- struct bpf_verifier_stack_elem *elem, *head = env->head;
- int err;
- if (env->head == NULL)
- return -ENOENT;
- if (cur) {
- err = copy_verifier_state(cur, &head->st);
- if (err)
- return err;
- }
- if (pop_log)
- bpf_vlog_reset(&env->log, head->log_pos);
- if (insn_idx)
- *insn_idx = head->insn_idx;
- if (prev_insn_idx)
- *prev_insn_idx = head->prev_insn_idx;
- elem = head->next;
- free_verifier_state(&head->st, false);
- kfree(head);
- env->head = elem;
- env->stack_size--;
- return 0;
- }
- static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
- int insn_idx, int prev_insn_idx,
- bool speculative)
- {
- struct bpf_verifier_state *cur = env->cur_state;
- struct bpf_verifier_stack_elem *elem;
- int err;
- elem = kzalloc(sizeof(struct bpf_verifier_stack_elem), GFP_KERNEL);
- if (!elem)
- goto err;
- elem->insn_idx = insn_idx;
- elem->prev_insn_idx = prev_insn_idx;
- elem->next = env->head;
- elem->log_pos = env->log.len_used;
- env->head = elem;
- env->stack_size++;
- err = copy_verifier_state(&elem->st, cur);
- if (err)
- goto err;
- elem->st.speculative |= speculative;
- if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
- verbose(env, "The sequence of %d jumps is too complex.\n",
- env->stack_size);
- goto err;
- }
- if (elem->st.parent) {
- ++elem->st.parent->branches;
- /* WARN_ON(branches > 2) technically makes sense here,
- * but
- * 1. speculative states will bump 'branches' for non-branch
- * instructions
- * 2. is_state_visited() heuristics may decide not to create
- * a new state for a sequence of branches and all such current
- * and cloned states will be pointing to a single parent state
- * which might have large 'branches' count.
- */
- }
- return &elem->st;
- err:
- free_verifier_state(env->cur_state, true);
- env->cur_state = NULL;
- /* pop all elements and return */
- while (!pop_stack(env, NULL, NULL, false));
- return NULL;
- }
- #define CALLER_SAVED_REGS 6
- static const int caller_saved[CALLER_SAVED_REGS] = {
- BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
- };
- static void __mark_reg_not_init(const struct bpf_verifier_env *env,
- struct bpf_reg_state *reg);
- /* This helper doesn't clear reg->id */
- static void ___mark_reg_known(struct bpf_reg_state *reg, u64 imm)
- {
- reg->var_off = tnum_const(imm);
- reg->smin_value = (s64)imm;
- reg->smax_value = (s64)imm;
- reg->umin_value = imm;
- reg->umax_value = imm;
- reg->s32_min_value = (s32)imm;
- reg->s32_max_value = (s32)imm;
- reg->u32_min_value = (u32)imm;
- reg->u32_max_value = (u32)imm;
- }
- /* Mark the unknown part of a register (variable offset or scalar value) as
- * known to have the value @imm.
- */
- static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm)
- {
- /* Clear id, off, and union(map_ptr, range) */
- memset(((u8 *)reg) + sizeof(reg->type), 0,
- offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type));
- ___mark_reg_known(reg, imm);
- }
- static void __mark_reg32_known(struct bpf_reg_state *reg, u64 imm)
- {
- reg->var_off = tnum_const_subreg(reg->var_off, imm);
- reg->s32_min_value = (s32)imm;
- reg->s32_max_value = (s32)imm;
- reg->u32_min_value = (u32)imm;
- reg->u32_max_value = (u32)imm;
- }
- /* Mark the 'variable offset' part of a register as zero. This should be
- * used only on registers holding a pointer type.
- */
- static void __mark_reg_known_zero(struct bpf_reg_state *reg)
- {
- __mark_reg_known(reg, 0);
- }
- static void __mark_reg_const_zero(struct bpf_reg_state *reg)
- {
- __mark_reg_known(reg, 0);
- reg->type = SCALAR_VALUE;
- }
- static void mark_reg_known_zero(struct bpf_verifier_env *env,
- struct bpf_reg_state *regs, u32 regno)
- {
- if (WARN_ON(regno >= MAX_BPF_REG)) {
- verbose(env, "mark_reg_known_zero(regs, %u)\n", regno);
- /* Something bad happened, let's kill all regs */
- for (regno = 0; regno < MAX_BPF_REG; regno++)
- __mark_reg_not_init(env, regs + regno);
- return;
- }
- __mark_reg_known_zero(regs + regno);
- }
- static bool reg_is_pkt_pointer(const struct bpf_reg_state *reg)
- {
- return type_is_pkt_pointer(reg->type);
- }
- static bool reg_is_pkt_pointer_any(const struct bpf_reg_state *reg)
- {
- return reg_is_pkt_pointer(reg) ||
- reg->type == PTR_TO_PACKET_END;
- }
- /* Unmodified PTR_TO_PACKET[_META,_END] register from ctx access. */
- static bool reg_is_init_pkt_pointer(const struct bpf_reg_state *reg,
- enum bpf_reg_type which)
- {
- /* The register can already have a range from prior markings.
- * This is fine as long as it hasn't been advanced from its
- * origin.
- */
- return reg->type == which &&
- reg->id == 0 &&
- reg->off == 0 &&
- tnum_equals_const(reg->var_off, 0);
- }
- /* Reset the min/max bounds of a register */
- static void __mark_reg_unbounded(struct bpf_reg_state *reg)
- {
- reg->smin_value = S64_MIN;
- reg->smax_value = S64_MAX;
- reg->umin_value = 0;
- reg->umax_value = U64_MAX;
- reg->s32_min_value = S32_MIN;
- reg->s32_max_value = S32_MAX;
- reg->u32_min_value = 0;
- reg->u32_max_value = U32_MAX;
- }
- static void __mark_reg64_unbounded(struct bpf_reg_state *reg)
- {
- reg->smin_value = S64_MIN;
- reg->smax_value = S64_MAX;
- reg->umin_value = 0;
- reg->umax_value = U64_MAX;
- }
- static void __mark_reg32_unbounded(struct bpf_reg_state *reg)
- {
- reg->s32_min_value = S32_MIN;
- reg->s32_max_value = S32_MAX;
- reg->u32_min_value = 0;
- reg->u32_max_value = U32_MAX;
- }
- static void __update_reg32_bounds(struct bpf_reg_state *reg)
- {
- struct tnum var32_off = tnum_subreg(reg->var_off);
- /* min signed is max(sign bit) | min(other bits) */
- reg->s32_min_value = max_t(s32, reg->s32_min_value,
- var32_off.value | (var32_off.mask & S32_MIN));
- /* max signed is min(sign bit) | max(other bits) */
- reg->s32_max_value = min_t(s32, reg->s32_max_value,
- var32_off.value | (var32_off.mask & S32_MAX));
- reg->u32_min_value = max_t(u32, reg->u32_min_value, (u32)var32_off.value);
- reg->u32_max_value = min(reg->u32_max_value,
- (u32)(var32_off.value | var32_off.mask));
- }
- static void __update_reg64_bounds(struct bpf_reg_state *reg)
- {
- /* min signed is max(sign bit) | min(other bits) */
- reg->smin_value = max_t(s64, reg->smin_value,
- reg->var_off.value | (reg->var_off.mask & S64_MIN));
- /* max signed is min(sign bit) | max(other bits) */
- reg->smax_value = min_t(s64, reg->smax_value,
- reg->var_off.value | (reg->var_off.mask & S64_MAX));
- reg->umin_value = max(reg->umin_value, reg->var_off.value);
- reg->umax_value = min(reg->umax_value,
- reg->var_off.value | reg->var_off.mask);
- }
- static void __update_reg_bounds(struct bpf_reg_state *reg)
- {
- __update_reg32_bounds(reg);
- __update_reg64_bounds(reg);
- }
- /* Uses signed min/max values to inform unsigned, and vice-versa */
- static void __reg32_deduce_bounds(struct bpf_reg_state *reg)
- {
- /* Learn sign from signed bounds.
- * If we cannot cross the sign boundary, then signed and unsigned bounds
- * are the same, so combine. This works even in the negative case, e.g.
- * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
- */
- if (reg->s32_min_value >= 0 || reg->s32_max_value < 0) {
- reg->s32_min_value = reg->u32_min_value =
- max_t(u32, reg->s32_min_value, reg->u32_min_value);
- reg->s32_max_value = reg->u32_max_value =
- min_t(u32, reg->s32_max_value, reg->u32_max_value);
- return;
- }
- /* Learn sign from unsigned bounds. Signed bounds cross the sign
- * boundary, so we must be careful.
- */
- if ((s32)reg->u32_max_value >= 0) {
- /* Positive. We can't learn anything from the smin, but smax
- * is positive, hence safe.
- */
- reg->s32_min_value = reg->u32_min_value;
- reg->s32_max_value = reg->u32_max_value =
- min_t(u32, reg->s32_max_value, reg->u32_max_value);
- } else if ((s32)reg->u32_min_value < 0) {
- /* Negative. We can't learn anything from the smax, but smin
- * is negative, hence safe.
- */
- reg->s32_min_value = reg->u32_min_value =
- max_t(u32, reg->s32_min_value, reg->u32_min_value);
- reg->s32_max_value = reg->u32_max_value;
- }
- }
- static void __reg64_deduce_bounds(struct bpf_reg_state *reg)
- {
- /* Learn sign from signed bounds.
- * If we cannot cross the sign boundary, then signed and unsigned bounds
- * are the same, so combine. This works even in the negative case, e.g.
- * -3 s<= x s<= -1 implies 0xf...fd u<= x u<= 0xf...ff.
- */
- if (reg->smin_value >= 0 || reg->smax_value < 0) {
- reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value,
- reg->umin_value);
- reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value,
- reg->umax_value);
- return;
- }
- /* Learn sign from unsigned bounds. Signed bounds cross the sign
- * boundary, so we must be careful.
- */
- if ((s64)reg->umax_value >= 0) {
- /* Positive. We can't learn anything from the smin, but smax
- * is positive, hence safe.
- */
- reg->smin_value = reg->umin_value;
- reg->smax_value = reg->umax_value = min_t(u64, reg->smax_value,
- reg->umax_value);
- } else if ((s64)reg->umin_value < 0) {
- /* Negative. We can't learn anything from the smax, but smin
- * is negative, hence safe.
- */
- reg->smin_value = reg->umin_value = max_t(u64, reg->smin_value,
- reg->umin_value);
- reg->smax_value = reg->umax_value;
- }
- }
- static void __reg_deduce_bounds(struct bpf_reg_state *reg)
- {
- __reg32_deduce_bounds(reg);
- __reg64_deduce_bounds(reg);
- }
- /* Attempts to improve var_off based on unsigned min/max information */
- static void __reg_bound_offset(struct bpf_reg_state *reg)
- {
- struct tnum var64_off = tnum_intersect(reg->var_off,
- tnum_range(reg->umin_value,
- reg->umax_value));
- struct tnum var32_off = tnum_intersect(tnum_subreg(reg->var_off),
- tnum_range(reg->u32_min_value,
- reg->u32_max_value));
- reg->var_off = tnum_or(tnum_clear_subreg(var64_off), var32_off);
- }
- static bool __reg32_bound_s64(s32 a)
- {
- return a >= 0 && a <= S32_MAX;
- }
- static void __reg_assign_32_into_64(struct bpf_reg_state *reg)
- {
- reg->umin_value = reg->u32_min_value;
- reg->umax_value = reg->u32_max_value;
- /* Attempt to pull 32-bit signed bounds into 64-bit bounds but must
- * be positive otherwise set to worse case bounds and refine later
- * from tnum.
- */
- if (__reg32_bound_s64(reg->s32_min_value) &&
- __reg32_bound_s64(reg->s32_max_value)) {
- reg->smin_value = reg->s32_min_value;
- reg->smax_value = reg->s32_max_value;
- } else {
- reg->smin_value = 0;
- reg->smax_value = U32_MAX;
- }
- }
- static void __reg_combine_32_into_64(struct bpf_reg_state *reg)
- {
- /* special case when 64-bit register has upper 32-bit register
- * zeroed. Typically happens after zext or <<32, >>32 sequence
- * allowing us to use 32-bit bounds directly,
- */
- if (tnum_equals_const(tnum_clear_subreg(reg->var_off), 0)) {
- __reg_assign_32_into_64(reg);
- } else {
- /* Otherwise the best we can do is push lower 32bit known and
- * unknown bits into register (var_off set from jmp logic)
- * then learn as much as possible from the 64-bit tnum
- * known and unknown bits. The previous smin/smax bounds are
- * invalid here because of jmp32 compare so mark them unknown
- * so they do not impact tnum bounds calculation.
- */
- __mark_reg64_unbounded(reg);
- __update_reg_bounds(reg);
- }
- /* Intersecting with the old var_off might have improved our bounds
- * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
- * then new var_off is (0; 0x7f...fc) which improves our umax.
- */
- __reg_deduce_bounds(reg);
- __reg_bound_offset(reg);
- __update_reg_bounds(reg);
- }
- static bool __reg64_bound_s32(s64 a)
- {
- return a >= S32_MIN && a <= S32_MAX;
- }
- static bool __reg64_bound_u32(u64 a)
- {
- return a >= U32_MIN && a <= U32_MAX;
- }
- static void __reg_combine_64_into_32(struct bpf_reg_state *reg)
- {
- __mark_reg32_unbounded(reg);
- if (__reg64_bound_s32(reg->smin_value) && __reg64_bound_s32(reg->smax_value)) {
- reg->s32_min_value = (s32)reg->smin_value;
- reg->s32_max_value = (s32)reg->smax_value;
- }
- if (__reg64_bound_u32(reg->umin_value) && __reg64_bound_u32(reg->umax_value)) {
- reg->u32_min_value = (u32)reg->umin_value;
- reg->u32_max_value = (u32)reg->umax_value;
- }
- /* Intersecting with the old var_off might have improved our bounds
- * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
- * then new var_off is (0; 0x7f...fc) which improves our umax.
- */
- __reg_deduce_bounds(reg);
- __reg_bound_offset(reg);
- __update_reg_bounds(reg);
- }
- /* Mark a register as having a completely unknown (scalar) value. */
- static void __mark_reg_unknown(const struct bpf_verifier_env *env,
- struct bpf_reg_state *reg)
- {
- /*
- * Clear type, id, off, and union(map_ptr, range) and
- * padding between 'type' and union
- */
- memset(reg, 0, offsetof(struct bpf_reg_state, var_off));
- reg->type = SCALAR_VALUE;
- reg->var_off = tnum_unknown;
- reg->frameno = 0;
- reg->precise = env->subprog_cnt > 1 || !env->bpf_capable;
- __mark_reg_unbounded(reg);
- }
- static void mark_reg_unknown(struct bpf_verifier_env *env,
- struct bpf_reg_state *regs, u32 regno)
- {
- if (WARN_ON(regno >= MAX_BPF_REG)) {
- verbose(env, "mark_reg_unknown(regs, %u)\n", regno);
- /* Something bad happened, let's kill all regs except FP */
- for (regno = 0; regno < BPF_REG_FP; regno++)
- __mark_reg_not_init(env, regs + regno);
- return;
- }
- __mark_reg_unknown(env, regs + regno);
- }
- static void __mark_reg_not_init(const struct bpf_verifier_env *env,
- struct bpf_reg_state *reg)
- {
- __mark_reg_unknown(env, reg);
- reg->type = NOT_INIT;
- }
- static void mark_reg_not_init(struct bpf_verifier_env *env,
- struct bpf_reg_state *regs, u32 regno)
- {
- if (WARN_ON(regno >= MAX_BPF_REG)) {
- verbose(env, "mark_reg_not_init(regs, %u)\n", regno);
- /* Something bad happened, let's kill all regs except FP */
- for (regno = 0; regno < BPF_REG_FP; regno++)
- __mark_reg_not_init(env, regs + regno);
- return;
- }
- __mark_reg_not_init(env, regs + regno);
- }
- static void mark_btf_ld_reg(struct bpf_verifier_env *env,
- struct bpf_reg_state *regs, u32 regno,
- enum bpf_reg_type reg_type, u32 btf_id)
- {
- if (reg_type == SCALAR_VALUE) {
- mark_reg_unknown(env, regs, regno);
- return;
- }
- mark_reg_known_zero(env, regs, regno);
- regs[regno].type = PTR_TO_BTF_ID;
- regs[regno].btf_id = btf_id;
- }
- #define DEF_NOT_SUBREG (0)
- static void init_reg_state(struct bpf_verifier_env *env,
- struct bpf_func_state *state)
- {
- struct bpf_reg_state *regs = state->regs;
- int i;
- for (i = 0; i < MAX_BPF_REG; i++) {
- mark_reg_not_init(env, regs, i);
- regs[i].live = REG_LIVE_NONE;
- regs[i].parent = NULL;
- regs[i].subreg_def = DEF_NOT_SUBREG;
- }
- /* frame pointer */
- regs[BPF_REG_FP].type = PTR_TO_STACK;
- mark_reg_known_zero(env, regs, BPF_REG_FP);
- regs[BPF_REG_FP].frameno = state->frameno;
- }
- #define BPF_MAIN_FUNC (-1)
- static void init_func_state(struct bpf_verifier_env *env,
- struct bpf_func_state *state,
- int callsite, int frameno, int subprogno)
- {
- state->callsite = callsite;
- state->frameno = frameno;
- state->subprogno = subprogno;
- init_reg_state(env, state);
- }
- enum reg_arg_type {
- SRC_OP, /* register is used as source operand */
- DST_OP, /* register is used as destination operand */
- DST_OP_NO_MARK /* same as above, check only, don't mark */
- };
- static int cmp_subprogs(const void *a, const void *b)
- {
- return ((struct bpf_subprog_info *)a)->start -
- ((struct bpf_subprog_info *)b)->start;
- }
- static int find_subprog(struct bpf_verifier_env *env, int off)
- {
- struct bpf_subprog_info *p;
- p = bsearch(&off, env->subprog_info, env->subprog_cnt,
- sizeof(env->subprog_info[0]), cmp_subprogs);
- if (!p)
- return -ENOENT;
- return p - env->subprog_info;
- }
- static int add_subprog(struct bpf_verifier_env *env, int off)
- {
- int insn_cnt = env->prog->len;
- int ret;
- if (off >= insn_cnt || off < 0) {
- verbose(env, "call to invalid destination\n");
- return -EINVAL;
- }
- ret = find_subprog(env, off);
- if (ret >= 0)
- return 0;
- if (env->subprog_cnt >= BPF_MAX_SUBPROGS) {
- verbose(env, "too many subprograms\n");
- return -E2BIG;
- }
- env->subprog_info[env->subprog_cnt++].start = off;
- sort(env->subprog_info, env->subprog_cnt,
- sizeof(env->subprog_info[0]), cmp_subprogs, NULL);
- return 0;
- }
- static int check_subprogs(struct bpf_verifier_env *env)
- {
- int i, ret, subprog_start, subprog_end, off, cur_subprog = 0;
- struct bpf_subprog_info *subprog = env->subprog_info;
- struct bpf_insn *insn = env->prog->insnsi;
- int insn_cnt = env->prog->len;
- /* Add entry function. */
- ret = add_subprog(env, 0);
- if (ret < 0)
- return ret;
- /* determine subprog starts. The end is one before the next starts */
- for (i = 0; i < insn_cnt; i++) {
- if (insn[i].code != (BPF_JMP | BPF_CALL))
- continue;
- if (insn[i].src_reg != BPF_PSEUDO_CALL)
- continue;
- if (!env->bpf_capable) {
- verbose(env,
- "function calls to other bpf functions are allowed for CAP_BPF and CAP_SYS_ADMIN\n");
- return -EPERM;
- }
- ret = add_subprog(env, i + insn[i].imm + 1);
- if (ret < 0)
- return ret;
- }
- /* Add a fake 'exit' subprog which could simplify subprog iteration
- * logic. 'subprog_cnt' should not be increased.
- */
- subprog[env->subprog_cnt].start = insn_cnt;
- if (env->log.level & BPF_LOG_LEVEL2)
- for (i = 0; i < env->subprog_cnt; i++)
- verbose(env, "func#%d @%d\n", i, subprog[i].start);
- /* now check that all jumps are within the same subprog */
- subprog_start = subprog[cur_subprog].start;
- subprog_end = subprog[cur_subprog + 1].start;
- for (i = 0; i < insn_cnt; i++) {
- u8 code = insn[i].code;
- if (code == (BPF_JMP | BPF_CALL) &&
- insn[i].imm == BPF_FUNC_tail_call &&
- insn[i].src_reg != BPF_PSEUDO_CALL)
- subprog[cur_subprog].has_tail_call = true;
- if (BPF_CLASS(code) == BPF_LD &&
- (BPF_MODE(code) == BPF_ABS || BPF_MODE(code) == BPF_IND))
- subprog[cur_subprog].has_ld_abs = true;
- if (BPF_CLASS(code) != BPF_JMP && BPF_CLASS(code) != BPF_JMP32)
- goto next;
- if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL)
- goto next;
- off = i + insn[i].off + 1;
- if (off < subprog_start || off >= subprog_end) {
- verbose(env, "jump out of range from insn %d to %d\n", i, off);
- return -EINVAL;
- }
- next:
- if (i == subprog_end - 1) {
- /* to avoid fall-through from one subprog into another
- * the last insn of the subprog should be either exit
- * or unconditional jump back
- */
- if (code != (BPF_JMP | BPF_EXIT) &&
- code != (BPF_JMP | BPF_JA)) {
- verbose(env, "last insn is not an exit or jmp\n");
- return -EINVAL;
- }
- subprog_start = subprog_end;
- cur_subprog++;
- if (cur_subprog < env->subprog_cnt)
- subprog_end = subprog[cur_subprog + 1].start;
- }
- }
- return 0;
- }
- /* Parentage chain of this register (or stack slot) should take care of all
- * issues like callee-saved registers, stack slot allocation time, etc.
- */
- static int mark_reg_read(struct bpf_verifier_env *env,
- const struct bpf_reg_state *state,
- struct bpf_reg_state *parent, u8 flag)
- {
- bool writes = parent == state->parent; /* Observe write marks */
- int cnt = 0;
- while (parent) {
- /* if read wasn't screened by an earlier write ... */
- if (writes && state->live & REG_LIVE_WRITTEN)
- break;
- if (parent->live & REG_LIVE_DONE) {
- verbose(env, "verifier BUG type %s var_off %lld off %d\n",
- reg_type_str[parent->type],
- parent->var_off.value, parent->off);
- return -EFAULT;
- }
- /* The first condition is more likely to be true than the
- * second, checked it first.
- */
- if ((parent->live & REG_LIVE_READ) == flag ||
- parent->live & REG_LIVE_READ64)
- /* The parentage chain never changes and
- * this parent was already marked as LIVE_READ.
- * There is no need to keep walking the chain again and
- * keep re-marking all parents as LIVE_READ.
- * This case happens when the same register is read
- * multiple times without writes into it in-between.
- * Also, if parent has the stronger REG_LIVE_READ64 set,
- * then no need to set the weak REG_LIVE_READ32.
- */
- break;
- /* ... then we depend on parent's value */
- parent->live |= flag;
- /* REG_LIVE_READ64 overrides REG_LIVE_READ32. */
- if (flag == REG_LIVE_READ64)
- parent->live &= ~REG_LIVE_READ32;
- state = parent;
- parent = state->parent;
- writes = true;
- cnt++;
- }
- if (env->longest_mark_read_walk < cnt)
- env->longest_mark_read_walk = cnt;
- return 0;
- }
- /* This function is supposed to be used by the following 32-bit optimization
- * code only. It returns TRUE if the source or destination register operates
- * on 64-bit, otherwise return FALSE.
- */
- static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn,
- u32 regno, struct bpf_reg_state *reg, enum reg_arg_type t)
- {
- u8 code, class, op;
- code = insn->code;
- class = BPF_CLASS(code);
- op = BPF_OP(code);
- if (class == BPF_JMP) {
- /* BPF_EXIT for "main" will reach here. Return TRUE
- * conservatively.
- */
- if (op == BPF_EXIT)
- return true;
- if (op == BPF_CALL) {
- /* BPF to BPF call will reach here because of marking
- * caller saved clobber with DST_OP_NO_MARK for which we
- * don't care the register def because they are anyway
- * marked as NOT_INIT already.
- */
- if (insn->src_reg == BPF_PSEUDO_CALL)
- return false;
- /* Helper call will reach here because of arg type
- * check, conservatively return TRUE.
- */
- if (t == SRC_OP)
- return true;
- return false;
- }
- }
- if (class == BPF_ALU64 || class == BPF_JMP ||
- /* BPF_END always use BPF_ALU class. */
- (class == BPF_ALU && op == BPF_END && insn->imm == 64))
- return true;
- if (class == BPF_ALU || class == BPF_JMP32)
- return false;
- if (class == BPF_LDX) {
- if (t != SRC_OP)
- return BPF_SIZE(code) == BPF_DW;
- /* LDX source must be ptr. */
- return true;
- }
- if (class == BPF_STX) {
- if (reg->type != SCALAR_VALUE)
- return true;
- return BPF_SIZE(code) == BPF_DW;
- }
- if (class == BPF_LD) {
- u8 mode = BPF_MODE(code);
- /* LD_IMM64 */
- if (mode == BPF_IMM)
- return true;
- /* Both LD_IND and LD_ABS return 32-bit data. */
- if (t != SRC_OP)
- return false;
- /* Implicit ctx ptr. */
- if (regno == BPF_REG_6)
- return true;
- /* Explicit source could be any width. */
- return true;
- }
- if (class == BPF_ST)
- /* The only source register for BPF_ST is a ptr. */
- return true;
- /* Conservatively return true at default. */
- return true;
- }
- /* Return TRUE if INSN doesn't have explicit value define. */
- static bool insn_no_def(struct bpf_insn *insn)
- {
- u8 class = BPF_CLASS(insn->code);
- return (class == BPF_JMP || class == BPF_JMP32 ||
- class == BPF_STX || class == BPF_ST);
- }
- /* Return TRUE if INSN has defined any 32-bit value explicitly. */
- static bool insn_has_def32(struct bpf_verifier_env *env, struct bpf_insn *insn)
- {
- if (insn_no_def(insn))
- return false;
- return !is_reg64(env, insn, insn->dst_reg, NULL, DST_OP);
- }
- static void mark_insn_zext(struct bpf_verifier_env *env,
- struct bpf_reg_state *reg)
- {
- s32 def_idx = reg->subreg_def;
- if (def_idx == DEF_NOT_SUBREG)
- return;
- env->insn_aux_data[def_idx - 1].zext_dst = true;
- /* The dst will be zero extended, so won't be sub-register anymore. */
- reg->subreg_def = DEF_NOT_SUBREG;
- }
- static int check_reg_arg(struct bpf_verifier_env *env, u32 regno,
- enum reg_arg_type t)
- {
- struct bpf_verifier_state *vstate = env->cur_state;
- struct bpf_func_state *state = vstate->frame[vstate->curframe];
- struct bpf_insn *insn = env->prog->insnsi + env->insn_idx;
- struct bpf_reg_state *reg, *regs = state->regs;
- bool rw64;
- if (regno >= MAX_BPF_REG) {
- verbose(env, "R%d is invalid\n", regno);
- return -EINVAL;
- }
- reg = ®s[regno];
- rw64 = is_reg64(env, insn, regno, reg, t);
- if (t == SRC_OP) {
- /* check whether register used as source operand can be read */
- if (reg->type == NOT_INIT) {
- verbose(env, "R%d !read_ok\n", regno);
- return -EACCES;
- }
- /* We don't need to worry about FP liveness because it's read-only */
- if (regno == BPF_REG_FP)
- return 0;
- if (rw64)
- mark_insn_zext(env, reg);
- return mark_reg_read(env, reg, reg->parent,
- rw64 ? REG_LIVE_READ64 : REG_LIVE_READ32);
- } else {
- /* check whether register used as dest operand can be written to */
- if (regno == BPF_REG_FP) {
- verbose(env, "frame pointer is read only\n");
- return -EACCES;
- }
- reg->live |= REG_LIVE_WRITTEN;
- reg->subreg_def = rw64 ? DEF_NOT_SUBREG : env->insn_idx + 1;
- if (t == DST_OP)
- mark_reg_unknown(env, regs, regno);
- }
- return 0;
- }
- /* for any branch, call, exit record the history of jmps in the given state */
- static int push_jmp_history(struct bpf_verifier_env *env,
- struct bpf_verifier_state *cur)
- {
- u32 cnt = cur->jmp_history_cnt;
- struct bpf_idx_pair *p;
- cnt++;
- p = krealloc(cur->jmp_history, cnt * sizeof(*p), GFP_USER);
- if (!p)
- return -ENOMEM;
- p[cnt - 1].idx = env->insn_idx;
- p[cnt - 1].prev_idx = env->prev_insn_idx;
- cur->jmp_history = p;
- cur->jmp_history_cnt = cnt;
- return 0;
- }
- /* Backtrack one insn at a time. If idx is not at the top of recorded
- * history then previous instruction came from straight line execution.
- */
- static int get_prev_insn_idx(struct bpf_verifier_state *st, int i,
- u32 *history)
- {
- u32 cnt = *history;
- if (cnt && st->jmp_history[cnt - 1].idx == i) {
- i = st->jmp_history[cnt - 1].prev_idx;
- (*history)--;
- } else {
- i--;
- }
- return i;
- }
- /* For given verifier state backtrack_insn() is called from the last insn to
- * the first insn. Its purpose is to compute a bitmask of registers and
- * stack slots that needs precision in the parent verifier state.
- */
- static int backtrack_insn(struct bpf_verifier_env *env, int idx,
- u32 *reg_mask, u64 *stack_mask)
- {
- const struct bpf_insn_cbs cbs = {
- .cb_print = verbose,
- .private_data = env,
- };
- struct bpf_insn *insn = env->prog->insnsi + idx;
- u8 class = BPF_CLASS(insn->code);
- u8 opcode = BPF_OP(insn->code);
- u8 mode = BPF_MODE(insn->code);
- u32 dreg = 1u << insn->dst_reg;
- u32 sreg = 1u << insn->src_reg;
- u32 spi;
- if (insn->code == 0)
- return 0;
- if (env->log.level & BPF_LOG_LEVEL) {
- verbose(env, "regs=%x stack=%llx before ", *reg_mask, *stack_mask);
- verbose(env, "%d: ", idx);
- print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
- }
- if (class == BPF_ALU || class == BPF_ALU64) {
- if (!(*reg_mask & dreg))
- return 0;
- if (opcode == BPF_MOV) {
- if (BPF_SRC(insn->code) == BPF_X) {
- /* dreg = sreg
- * dreg needs precision after this insn
- * sreg needs precision before this insn
- */
- *reg_mask &= ~dreg;
- *reg_mask |= sreg;
- } else {
- /* dreg = K
- * dreg needs precision after this insn.
- * Corresponding register is already marked
- * as precise=true in this verifier state.
- * No further markings in parent are necessary
- */
- *reg_mask &= ~dreg;
- }
- } else {
- if (BPF_SRC(insn->code) == BPF_X) {
- /* dreg += sreg
- * both dreg and sreg need precision
- * before this insn
- */
- *reg_mask |= sreg;
- } /* else dreg += K
- * dreg still needs precision before this insn
- */
- }
- } else if (class == BPF_LDX) {
- if (!(*reg_mask & dreg))
- return 0;
- *reg_mask &= ~dreg;
- /* scalars can only be spilled into stack w/o losing precision.
- * Load from any other memory can be zero extended.
- * The desire to keep that precision is already indicated
- * by 'precise' mark in corresponding register of this state.
- * No further tracking necessary.
- */
- if (insn->src_reg != BPF_REG_FP)
- return 0;
- if (BPF_SIZE(insn->code) != BPF_DW)
- return 0;
- /* dreg = *(u64 *)[fp - off] was a fill from the stack.
- * that [fp - off] slot contains scalar that needs to be
- * tracked with precision
- */
- spi = (-insn->off - 1) / BPF_REG_SIZE;
- if (spi >= 64) {
- verbose(env, "BUG spi %d\n", spi);
- WARN_ONCE(1, "verifier backtracking bug");
- return -EFAULT;
- }
- *stack_mask |= 1ull << spi;
- } else if (class == BPF_STX || class == BPF_ST) {
- if (*reg_mask & dreg)
- /* stx & st shouldn't be using _scalar_ dst_reg
- * to access memory. It means backtracking
- * encountered a case of pointer subtraction.
- */
- return -ENOTSUPP;
- /* scalars can only be spilled into stack */
- if (insn->dst_reg != BPF_REG_FP)
- return 0;
- if (BPF_SIZE(insn->code) != BPF_DW)
- return 0;
- spi = (-insn->off - 1) / BPF_REG_SIZE;
- if (spi >= 64) {
- verbose(env, "BUG spi %d\n", spi);
- WARN_ONCE(1, "verifier backtracking bug");
- return -EFAULT;
- }
- if (!(*stack_mask & (1ull << spi)))
- return 0;
- *stack_mask &= ~(1ull << spi);
- if (class == BPF_STX)
- *reg_mask |= sreg;
- } else if (class == BPF_JMP || class == BPF_JMP32) {
- if (opcode == BPF_CALL) {
- if (insn->src_reg == BPF_PSEUDO_CALL)
- return -ENOTSUPP;
- /* regular helper call sets R0 */
- *reg_mask &= ~1;
- if (*reg_mask & 0x3f) {
- /* if backtracing was looking for registers R1-R5
- * they should have been found already.
- */
- verbose(env, "BUG regs %x\n", *reg_mask);
- WARN_ONCE(1, "verifier backtracking bug");
- return -EFAULT;
- }
- } else if (opcode == BPF_EXIT) {
- return -ENOTSUPP;
- }
- } else if (class == BPF_LD) {
- if (!(*reg_mask & dreg))
- return 0;
- *reg_mask &= ~dreg;
- /* It's ld_imm64 or ld_abs or ld_ind.
- * For ld_imm64 no further tracking of precision
- * into parent is necessary
- */
- if (mode == BPF_IND || mode == BPF_ABS)
- /* to be analyzed */
- return -ENOTSUPP;
- }
- return 0;
- }
- /* the scalar precision tracking algorithm:
- * . at the start all registers have precise=false.
- * . scalar ranges are tracked as normal through alu and jmp insns.
- * . once precise value of the scalar register is used in:
- * . ptr + scalar alu
- * . if (scalar cond K|scalar)
- * . helper_call(.., scalar, ...) where ARG_CONST is expected
- * backtrack through the verifier states and mark all registers and
- * stack slots with spilled constants that these scalar regisers
- * should be precise.
- * . during state pruning two registers (or spilled stack slots)
- * are equivalent if both are not precise.
- *
- * Note the verifier cannot simply walk register parentage chain,
- * since many different registers and stack slots could have been
- * used to compute single precise scalar.
- *
- * The approach of starting with precise=true for all registers and then
- * backtrack to mark a register as not precise when the verifier detects
- * that program doesn't care about specific value (e.g., when helper
- * takes register as ARG_ANYTHING parameter) is not safe.
- *
- * It's ok to walk single parentage chain of the verifier states.
- * It's possible that this backtracking will go all the way till 1st insn.
- * All other branches will be explored for needing precision later.
- *
- * The backtracking needs to deal with cases like:
- * R8=map_value(id=0,off=0,ks=4,vs=1952,imm=0) R9_w=map_value(id=0,off=40,ks=4,vs=1952,imm=0)
- * r9 -= r8
- * r5 = r9
- * if r5 > 0x79f goto pc+7
- * R5_w=inv(id=0,umax_value=1951,var_off=(0x0; 0x7ff))
- * r5 += 1
- * ...
- * call bpf_perf_event_output#25
- * where .arg5_type = ARG_CONST_SIZE_OR_ZERO
- *
- * and this case:
- * r6 = 1
- * call foo // uses callee's r6 inside to compute r0
- * r0 += r6
- * if r0 == 0 goto
- *
- * to track above reg_mask/stack_mask needs to be independent for each frame.
- *
- * Also if parent's curframe > frame where backtracking started,
- * the verifier need to mark registers in both frames, otherwise callees
- * may incorrectly prune callers. This is similar to
- * commit 7640ead93924 ("bpf: verifier: make sure callees don't prune with caller differences")
- *
- * For now backtracking falls back into conservative marking.
- */
- static void mark_all_scalars_precise(struct bpf_verifier_env *env,
- struct bpf_verifier_state *st)
- {
- struct bpf_func_state *func;
- struct bpf_reg_state *reg;
- int i, j;
- /* big hammer: mark all scalars precise in this path.
- * pop_stack may still get !precise scalars.
- */
- for (; st; st = st->parent)
- for (i = 0; i <= st->curframe; i++) {
- func = st->frame[i];
- for (j = 0; j < BPF_REG_FP; j++) {
- reg = &func->regs[j];
- if (reg->type != SCALAR_VALUE)
- continue;
- reg->precise = true;
- }
- for (j = 0; j < func->allocated_stack / BPF_REG_SIZE; j++) {
- if (func->stack[j].slot_type[0] != STACK_SPILL)
- continue;
- reg = &func->stack[j].spilled_ptr;
- if (reg->type != SCALAR_VALUE)
- continue;
- reg->precise = true;
- }
- }
- }
- static int __mark_chain_precision(struct bpf_verifier_env *env, int regno,
- int spi)
- {
- struct bpf_verifier_state *st = env->cur_state;
- int first_idx = st->first_insn_idx;
- int last_idx = env->insn_idx;
- struct bpf_func_state *func;
- struct bpf_reg_state *reg;
- u32 reg_mask = regno >= 0 ? 1u << regno : 0;
- u64 stack_mask = spi >= 0 ? 1ull << spi : 0;
- bool skip_first = true;
- bool new_marks = false;
- int i, err;
- if (!env->bpf_capable)
- return 0;
- func = st->frame[st->curframe];
- if (regno >= 0) {
- reg = &func->regs[regno];
- if (reg->type != SCALAR_VALUE) {
- WARN_ONCE(1, "backtracing misuse");
- return -EFAULT;
- }
- if (!reg->precise)
- new_marks = true;
- else
- reg_mask = 0;
- reg->precise = true;
- }
- while (spi >= 0) {
- if (func->stack[spi].slot_type[0] != STACK_SPILL) {
- stack_mask = 0;
- break;
- }
- reg = &func->stack[spi].spilled_ptr;
- if (reg->type != SCALAR_VALUE) {
- stack_mask = 0;
- break;
- }
- if (!reg->precise)
- new_marks = true;
- else
- stack_mask = 0;
- reg->precise = true;
- break;
- }
- if (!new_marks)
- return 0;
- if (!reg_mask && !stack_mask)
- return 0;
- for (;;) {
- DECLARE_BITMAP(mask, 64);
- u32 history = st->jmp_history_cnt;
- if (env->log.level & BPF_LOG_LEVEL)
- verbose(env, "last_idx %d first_idx %d\n", last_idx, first_idx);
- for (i = last_idx;;) {
- if (skip_first) {
- err = 0;
- skip_first = false;
- } else {
- err = backtrack_insn(env, i, ®_mask, &stack_mask);
- }
- if (err == -ENOTSUPP) {
- mark_all_scalars_precise(env, st);
- return 0;
- } else if (err) {
- return err;
- }
- if (!reg_mask && !stack_mask)
- /* Found assignment(s) into tracked register in this state.
- * Since this state is already marked, just return.
- * Nothing to be tracked further in the parent state.
- */
- return 0;
- if (i == first_idx)
- break;
- i = get_prev_insn_idx(st, i, &history);
- if (i >= env->prog->len) {
- /* This can happen if backtracking reached insn 0
- * and there are still reg_mask or stack_mask
- * to backtrack.
- * It means the backtracking missed the spot where
- * particular register was initialized with a constant.
- */
- verbose(env, "BUG backtracking idx %d\n", i);
- WARN_ONCE(1, "verifier backtracking bug");
- return -EFAULT;
- }
- }
- st = st->parent;
- if (!st)
- break;
- new_marks = false;
- func = st->frame[st->curframe];
- bitmap_from_u64(mask, reg_mask);
- for_each_set_bit(i, mask, 32) {
- reg = &func->regs[i];
- if (reg->type != SCALAR_VALUE) {
- reg_mask &= ~(1u << i);
- continue;
- }
- if (!reg->precise)
- new_marks = true;
- reg->precise = true;
- }
- bitmap_from_u64(mask, stack_mask);
- for_each_set_bit(i, mask, 64) {
- if (i >= func->allocated_stack / BPF_REG_SIZE) {
- /* the sequence of instructions:
- * 2: (bf) r3 = r10
- * 3: (7b) *(u64 *)(r3 -8) = r0
- * 4: (79) r4 = *(u64 *)(r10 -8)
- * doesn't contain jmps. It's backtracked
- * as a single block.
- * During backtracking insn 3 is not recognized as
- * stack access, so at the end of backtracking
- * stack slot fp-8 is still marked in stack_mask.
- * However the parent state may not have accessed
- * fp-8 and it's "unallocated" stack space.
- * In such case fallback to conservative.
- */
- mark_all_scalars_precise(env, st);
- return 0;
- }
- if (func->stack[i].slot_type[0] != STACK_SPILL) {
- stack_mask &= ~(1ull << i);
- continue;
- }
- reg = &func->stack[i].spilled_ptr;
- if (reg->type != SCALAR_VALUE) {
- stack_mask &= ~(1ull << i);
- continue;
- }
- if (!reg->precise)
- new_marks = true;
- reg->precise = true;
- }
- if (env->log.level & BPF_LOG_LEVEL) {
- print_verifier_state(env, func);
- verbose(env, "parent %s regs=%x stack=%llx marks\n",
- new_marks ? "didn't have" : "already had",
- reg_mask, stack_mask);
- }
- if (!reg_mask && !stack_mask)
- break;
- if (!new_marks)
- break;
- last_idx = st->last_insn_idx;
- first_idx = st->first_insn_idx;
- }
- return 0;
- }
- static int mark_chain_precision(struct bpf_verifier_env *env, int regno)
- {
- return __mark_chain_precision(env, regno, -1);
- }
- static int mark_chain_precision_stack(struct bpf_verifier_env *env, int spi)
- {
- return __mark_chain_precision(env, -1, spi);
- }
- static bool is_spillable_regtype(enum bpf_reg_type type)
- {
- switch (type) {
- case PTR_TO_MAP_VALUE:
- case PTR_TO_MAP_VALUE_OR_NULL:
- case PTR_TO_STACK:
- case PTR_TO_CTX:
- case PTR_TO_PACKET:
- case PTR_TO_PACKET_META:
- case PTR_TO_PACKET_END:
- case PTR_TO_FLOW_KEYS:
- case CONST_PTR_TO_MAP:
- case PTR_TO_SOCKET:
- case PTR_TO_SOCKET_OR_NULL:
- case PTR_TO_SOCK_COMMON:
- case PTR_TO_SOCK_COMMON_OR_NULL:
- case PTR_TO_TCP_SOCK:
- case PTR_TO_TCP_SOCK_OR_NULL:
- case PTR_TO_XDP_SOCK:
- case PTR_TO_BTF_ID:
- case PTR_TO_BTF_ID_OR_NULL:
- case PTR_TO_RDONLY_BUF:
- case PTR_TO_RDONLY_BUF_OR_NULL:
- case PTR_TO_RDWR_BUF:
- case PTR_TO_RDWR_BUF_OR_NULL:
- case PTR_TO_PERCPU_BTF_ID:
- case PTR_TO_MEM:
- case PTR_TO_MEM_OR_NULL:
- return true;
- default:
- return false;
- }
- }
- /* Does this register contain a constant zero? */
- static bool register_is_null(struct bpf_reg_state *reg)
- {
- return reg->type == SCALAR_VALUE && tnum_equals_const(reg->var_off, 0);
- }
- static bool register_is_const(struct bpf_reg_state *reg)
- {
- return reg->type == SCALAR_VALUE && tnum_is_const(reg->var_off);
- }
- static bool __is_scalar_unbounded(struct bpf_reg_state *reg)
- {
- return tnum_is_unknown(reg->var_off) &&
- reg->smin_value == S64_MIN && reg->smax_value == S64_MAX &&
- reg->umin_value == 0 && reg->umax_value == U64_MAX &&
- reg->s32_min_value == S32_MIN && reg->s32_max_value == S32_MAX &&
- reg->u32_min_value == 0 && reg->u32_max_value == U32_MAX;
- }
- static bool register_is_bounded(struct bpf_reg_state *reg)
- {
- return reg->type == SCALAR_VALUE && !__is_scalar_unbounded(reg);
- }
- static bool __is_pointer_value(bool allow_ptr_leaks,
- const struct bpf_reg_state *reg)
- {
- if (allow_ptr_leaks)
- return false;
- return reg->type != SCALAR_VALUE;
- }
- static void save_register_state(struct bpf_func_state *state,
- int spi, struct bpf_reg_state *reg)
- {
- int i;
- state->stack[spi].spilled_ptr = *reg;
- state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
- for (i = 0; i < BPF_REG_SIZE; i++)
- state->stack[spi].slot_type[i] = STACK_SPILL;
- }
- /* check_stack_{read,write}_fixed_off functions track spill/fill of registers,
- * stack boundary and alignment are checked in check_mem_access()
- */
- static int check_stack_write_fixed_off(struct bpf_verifier_env *env,
- /* stack frame we're writing to */
- struct bpf_func_state *state,
- int off, int size, int value_regno,
- int insn_idx)
- {
- struct bpf_func_state *cur; /* state of the current function */
- int i, slot = -off - 1, spi = slot / BPF_REG_SIZE, err;
- u32 dst_reg = env->prog->insnsi[insn_idx].dst_reg;
- struct bpf_reg_state *reg = NULL;
- err = realloc_func_state(state, round_up(slot + 1, BPF_REG_SIZE),
- state->acquired_refs, true);
- if (err)
- return err;
- /* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
- * so it's aligned access and [off, off + size) are within stack limits
- */
- if (!env->allow_ptr_leaks &&
- state->stack[spi].slot_type[0] == STACK_SPILL &&
- size != BPF_REG_SIZE) {
- verbose(env, "attempt to corrupt spilled pointer on stack\n");
- return -EACCES;
- }
- cur = env->cur_state->frame[env->cur_state->curframe];
- if (value_regno >= 0)
- reg = &cur->regs[value_regno];
- if (!env->bypass_spec_v4) {
- bool sanitize = reg && is_spillable_regtype(reg->type);
- for (i = 0; i < size; i++) {
- if (state->stack[spi].slot_type[i] == STACK_INVALID) {
- sanitize = true;
- break;
- }
- }
- if (sanitize)
- env->insn_aux_data[insn_idx].sanitize_stack_spill = true;
- }
- if (reg && size == BPF_REG_SIZE && register_is_bounded(reg) &&
- !register_is_null(reg) && env->bpf_capable) {
- if (dst_reg != BPF_REG_FP) {
- /* The backtracking logic can only recognize explicit
- * stack slot address like [fp - 8]. Other spill of
- * scalar via different register has to be conervative.
- * Backtrack from here and mark all registers as precise
- * that contributed into 'reg' being a constant.
- */
- err = mark_chain_precision(env, value_regno);
- if (err)
- return err;
- }
- save_register_state(state, spi, reg);
- } else if (reg && is_spillable_regtype(reg->type)) {
- /* register containing pointer is being spilled into stack */
- if (size != BPF_REG_SIZE) {
- verbose_linfo(env, insn_idx, "; ");
- verbose(env, "invalid size of register spill\n");
- return -EACCES;
- }
- if (state != cur && reg->type == PTR_TO_STACK) {
- verbose(env, "cannot spill pointers to stack into stack frame of the caller\n");
- return -EINVAL;
- }
- save_register_state(state, spi, reg);
- } else {
- u8 type = STACK_MISC;
- /* regular write of data into stack destroys any spilled ptr */
- state->stack[spi].spilled_ptr.type = NOT_INIT;
- /* Mark slots as STACK_MISC if they belonged to spilled ptr. */
- if (state->stack[spi].slot_type[0] == STACK_SPILL)
- for (i = 0; i < BPF_REG_SIZE; i++)
- state->stack[spi].slot_type[i] = STACK_MISC;
- /* only mark the slot as written if all 8 bytes were written
- * otherwise read propagation may incorrectly stop too soon
- * when stack slots are partially written.
- * This heuristic means that read propagation will be
- * conservative, since it will add reg_live_read marks
- * to stack slots all the way to first state when programs
- * writes+reads less than 8 bytes
- */
- if (size == BPF_REG_SIZE)
- state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
- /* when we zero initialize stack slots mark them as such */
- if (reg && register_is_null(reg)) {
- /* backtracking doesn't work for STACK_ZERO yet. */
- err = mark_chain_precision(env, value_regno);
- if (err)
- return err;
- type = STACK_ZERO;
- }
- /* Mark slots affected by this stack write. */
- for (i = 0; i < size; i++)
- state->stack[spi].slot_type[(slot - i) % BPF_REG_SIZE] =
- type;
- }
- return 0;
- }
- /* Write the stack: 'stack[ptr_regno + off] = value_regno'. 'ptr_regno' is
- * known to contain a variable offset.
- * This function checks whether the write is permitted and conservatively
- * tracks the effects of the write, considering that each stack slot in the
- * dynamic range is potentially written to.
- *
- * 'off' includes 'regno->off'.
- * 'value_regno' can be -1, meaning that an unknown value is being written to
- * the stack.
- *
- * Spilled pointers in range are not marked as written because we don't know
- * what's going to be actually written. This means that read propagation for
- * future reads cannot be terminated by this write.
- *
- * For privileged programs, uninitialized stack slots are considered
- * initialized by this write (even though we don't know exactly what offsets
- * are going to be written to). The idea is that we don't want the verifier to
- * reject future reads that access slots written to through variable offsets.
- */
- static int check_stack_write_var_off(struct bpf_verifier_env *env,
- /* func where register points to */
- struct bpf_func_state *state,
- int ptr_regno, int off, int size,
- int value_regno, int insn_idx)
- {
- struct bpf_func_state *cur; /* state of the current function */
- int min_off, max_off;
- int i, err;
- struct bpf_reg_state *ptr_reg = NULL, *value_reg = NULL;
- bool writing_zero = false;
- /* set if the fact that we're writing a zero is used to let any
- * stack slots remain STACK_ZERO
- */
- bool zero_used = false;
- cur = env->cur_state->frame[env->cur_state->curframe];
- ptr_reg = &cur->regs[ptr_regno];
- min_off = ptr_reg->smin_value + off;
- max_off = ptr_reg->smax_value + off + size;
- if (value_regno >= 0)
- value_reg = &cur->regs[value_regno];
- if (value_reg && register_is_null(value_reg))
- writing_zero = true;
- err = realloc_func_state(state, round_up(-min_off, BPF_REG_SIZE),
- state->acquired_refs, true);
- if (err)
- return err;
- /* Variable offset writes destroy any spilled pointers in range. */
- for (i = min_off; i < max_off; i++) {
- u8 new_type, *stype;
- int slot, spi;
- slot = -i - 1;
- spi = slot / BPF_REG_SIZE;
- stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
- if (!env->allow_ptr_leaks
- && *stype != NOT_INIT
- && *stype != SCALAR_VALUE) {
- /* Reject the write if there's are spilled pointers in
- * range. If we didn't reject here, the ptr status
- * would be erased below (even though not all slots are
- * actually overwritten), possibly opening the door to
- * leaks.
- */
- verbose(env, "spilled ptr in range of var-offset stack write; insn %d, ptr off: %d",
- insn_idx, i);
- return -EINVAL;
- }
- /* Erase all spilled pointers. */
- state->stack[spi].spilled_ptr.type = NOT_INIT;
- /* Update the slot type. */
- new_type = STACK_MISC;
- if (writing_zero && *stype == STACK_ZERO) {
- new_type = STACK_ZERO;
- zero_used = true;
- }
- /* If the slot is STACK_INVALID, we check whether it's OK to
- * pretend that it will be initialized by this write. The slot
- * might not actually be written to, and so if we mark it as
- * initialized future reads might leak uninitialized memory.
- * For privileged programs, we will accept such reads to slots
- * that may or may not be written because, if we're reject
- * them, the error would be too confusing.
- */
- if (*stype == STACK_INVALID && !env->allow_uninit_stack) {
- verbose(env, "uninit stack in range of var-offset write prohibited for !root; insn %d, off: %d",
- insn_idx, i);
- return -EINVAL;
- }
- *stype = new_type;
- }
- if (zero_used) {
- /* backtracking doesn't work for STACK_ZERO yet. */
- err = mark_chain_precision(env, value_regno);
- if (err)
- return err;
- }
- return 0;
- }
- /* When register 'dst_regno' is assigned some values from stack[min_off,
- * max_off), we set the register's type according to the types of the
- * respective stack slots. If all the stack values are known to be zeros, then
- * so is the destination reg. Otherwise, the register is considered to be
- * SCALAR. This function does not deal with register filling; the caller must
- * ensure that all spilled registers in the stack range have been marked as
- * read.
- */
- static void mark_reg_stack_read(struct bpf_verifier_env *env,
- /* func where src register points to */
- struct bpf_func_state *ptr_state,
- int min_off, int max_off, int dst_regno)
- {
- struct bpf_verifier_state *vstate = env->cur_state;
- struct bpf_func_state *state = vstate->frame[vstate->curframe];
- int i, slot, spi;
- u8 *stype;
- int zeros = 0;
- for (i = min_off; i < max_off; i++) {
- slot = -i - 1;
- spi = slot / BPF_REG_SIZE;
- stype = ptr_state->stack[spi].slot_type;
- if (stype[slot % BPF_REG_SIZE] != STACK_ZERO)
- break;
- zeros++;
- }
- if (zeros == max_off - min_off) {
- /* any access_size read into register is zero extended,
- * so the whole register == const_zero
- */
- __mark_reg_const_zero(&state->regs[dst_regno]);
- /* backtracking doesn't support STACK_ZERO yet,
- * so mark it precise here, so that later
- * backtracking can stop here.
- * Backtracking may not need this if this register
- * doesn't participate in pointer adjustment.
- * Forward propagation of precise flag is not
- * necessary either. This mark is only to stop
- * backtracking. Any register that contributed
- * to const 0 was marked precise before spill.
- */
- state->regs[dst_regno].precise = true;
- } else {
- /* have read misc data from the stack */
- mark_reg_unknown(env, state->regs, dst_regno);
- }
- state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
- }
- /* Read the stack at 'off' and put the results into the register indicated by
- * 'dst_regno'. It handles reg filling if the addressed stack slot is a
- * spilled reg.
- *
- * 'dst_regno' can be -1, meaning that the read value is not going to a
- * register.
- *
- * The access is assumed to be within the current stack bounds.
- */
- static int check_stack_read_fixed_off(struct bpf_verifier_env *env,
- /* func where src register points to */
- struct bpf_func_state *reg_state,
- int off, int size, int dst_regno)
- {
- struct bpf_verifier_state *vstate = env->cur_state;
- struct bpf_func_state *state = vstate->frame[vstate->curframe];
- int i, slot = -off - 1, spi = slot / BPF_REG_SIZE;
- struct bpf_reg_state *reg;
- u8 *stype;
- stype = reg_state->stack[spi].slot_type;
- reg = ®_state->stack[spi].spilled_ptr;
- if (stype[0] == STACK_SPILL) {
- if (size != BPF_REG_SIZE) {
- if (reg->type != SCALAR_VALUE) {
- verbose_linfo(env, env->insn_idx, "; ");
- verbose(env, "invalid size of register fill\n");
- return -EACCES;
- }
- if (dst_regno >= 0) {
- mark_reg_unknown(env, state->regs, dst_regno);
- state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
- }
- mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
- return 0;
- }
- for (i = 1; i < BPF_REG_SIZE; i++) {
- if (stype[(slot - i) % BPF_REG_SIZE] != STACK_SPILL) {
- verbose(env, "corrupted spill memory\n");
- return -EACCES;
- }
- }
- if (dst_regno >= 0) {
- /* restore register state from stack */
- state->regs[dst_regno] = *reg;
- /* mark reg as written since spilled pointer state likely
- * has its liveness marks cleared by is_state_visited()
- * which resets stack/reg liveness for state transitions
- */
- state->regs[dst_regno].live |= REG_LIVE_WRITTEN;
- } else if (__is_pointer_value(env->allow_ptr_leaks, reg)) {
- /* If dst_regno==-1, the caller is asking us whether
- * it is acceptable to use this value as a SCALAR_VALUE
- * (e.g. for XADD).
- * We must not allow unprivileged callers to do that
- * with spilled pointers.
- */
- verbose(env, "leaking pointer from stack off %d\n",
- off);
- return -EACCES;
- }
- mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
- } else {
- u8 type;
- for (i = 0; i < size; i++) {
- type = stype[(slot - i) % BPF_REG_SIZE];
- if (type == STACK_MISC)
- continue;
- if (type == STACK_ZERO)
- continue;
- verbose(env, "invalid read from stack off %d+%d size %d\n",
- off, i, size);
- return -EACCES;
- }
- mark_reg_read(env, reg, reg->parent, REG_LIVE_READ64);
- if (dst_regno >= 0)
- mark_reg_stack_read(env, reg_state, off, off + size, dst_regno);
- }
- return 0;
- }
- enum stack_access_src {
- ACCESS_DIRECT = 1, /* the access is performed by an instruction */
- ACCESS_HELPER = 2, /* the access is performed by a helper */
- };
- static int check_stack_range_initialized(struct bpf_verifier_env *env,
- int regno, int off, int access_size,
- bool zero_size_allowed,
- enum stack_access_src type,
- struct bpf_call_arg_meta *meta);
- static struct bpf_reg_state *reg_state(struct bpf_verifier_env *env, int regno)
- {
- return cur_regs(env) + regno;
- }
- /* Read the stack at 'ptr_regno + off' and put the result into the register
- * 'dst_regno'.
- * 'off' includes the pointer register's fixed offset(i.e. 'ptr_regno.off'),
- * but not its variable offset.
- * 'size' is assumed to be <= reg size and the access is assumed to be aligned.
- *
- * As opposed to check_stack_read_fixed_off, this function doesn't deal with
- * filling registers (i.e. reads of spilled register cannot be detected when
- * the offset is not fixed). We conservatively mark 'dst_regno' as containing
- * SCALAR_VALUE. That's why we assert that the 'ptr_regno' has a variable
- * offset; for a fixed offset check_stack_read_fixed_off should be used
- * instead.
- */
- static int check_stack_read_var_off(struct bpf_verifier_env *env,
- int ptr_regno, int off, int size, int dst_regno)
- {
- /* The state of the source register. */
- struct bpf_reg_state *reg = reg_state(env, ptr_regno);
- struct bpf_func_state *ptr_state = func(env, reg);
- int err;
- int min_off, max_off;
- /* Note that we pass a NULL meta, so raw access will not be permitted.
- */
- err = check_stack_range_initialized(env, ptr_regno, off, size,
- false, ACCESS_DIRECT, NULL);
- if (err)
- return err;
- min_off = reg->smin_value + off;
- max_off = reg->smax_value + off;
- mark_reg_stack_read(env, ptr_state, min_off, max_off + size, dst_regno);
- return 0;
- }
- /* check_stack_read dispatches to check_stack_read_fixed_off or
- * check_stack_read_var_off.
- *
- * The caller must ensure that the offset falls within the allocated stack
- * bounds.
- *
- * 'dst_regno' is a register which will receive the value from the stack. It
- * can be -1, meaning that the read value is not going to a register.
- */
- static int check_stack_read(struct bpf_verifier_env *env,
- int ptr_regno, int off, int size,
- int dst_regno)
- {
- struct bpf_reg_state *reg = reg_state(env, ptr_regno);
- struct bpf_func_state *state = func(env, reg);
- int err;
- /* Some accesses are only permitted with a static offset. */
- bool var_off = !tnum_is_const(reg->var_off);
- /* The offset is required to be static when reads don't go to a
- * register, in order to not leak pointers (see
- * check_stack_read_fixed_off).
- */
- if (dst_regno < 0 && var_off) {
- char tn_buf[48];
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env, "variable offset stack pointer cannot be passed into helper function; var_off=%s off=%d size=%d\n",
- tn_buf, off, size);
- return -EACCES;
- }
- /* Variable offset is prohibited for unprivileged mode for simplicity
- * since it requires corresponding support in Spectre masking for stack
- * ALU. See also retrieve_ptr_limit().
- */
- if (!env->bypass_spec_v1 && var_off) {
- char tn_buf[48];
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env, "R%d variable offset stack access prohibited for !root, var_off=%s\n",
- ptr_regno, tn_buf);
- return -EACCES;
- }
- if (!var_off) {
- off += reg->var_off.value;
- err = check_stack_read_fixed_off(env, state, off, size,
- dst_regno);
- } else {
- /* Variable offset stack reads need more conservative handling
- * than fixed offset ones. Note that dst_regno >= 0 on this
- * branch.
- */
- err = check_stack_read_var_off(env, ptr_regno, off, size,
- dst_regno);
- }
- return err;
- }
- /* check_stack_write dispatches to check_stack_write_fixed_off or
- * check_stack_write_var_off.
- *
- * 'ptr_regno' is the register used as a pointer into the stack.
- * 'off' includes 'ptr_regno->off', but not its variable offset (if any).
- * 'value_regno' is the register whose value we're writing to the stack. It can
- * be -1, meaning that we're not writing from a register.
- *
- * The caller must ensure that the offset falls within the maximum stack size.
- */
- static int check_stack_write(struct bpf_verifier_env *env,
- int ptr_regno, int off, int size,
- int value_regno, int insn_idx)
- {
- struct bpf_reg_state *reg = reg_state(env, ptr_regno);
- struct bpf_func_state *state = func(env, reg);
- int err;
- if (tnum_is_const(reg->var_off)) {
- off += reg->var_off.value;
- err = check_stack_write_fixed_off(env, state, off, size,
- value_regno, insn_idx);
- } else {
- /* Variable offset stack reads need more conservative handling
- * than fixed offset ones.
- */
- err = check_stack_write_var_off(env, state,
- ptr_regno, off, size,
- value_regno, insn_idx);
- }
- return err;
- }
- static int check_map_access_type(struct bpf_verifier_env *env, u32 regno,
- int off, int size, enum bpf_access_type type)
- {
- struct bpf_reg_state *regs = cur_regs(env);
- struct bpf_map *map = regs[regno].map_ptr;
- u32 cap = bpf_map_flags_to_cap(map);
- if (type == BPF_WRITE && !(cap & BPF_MAP_CAN_WRITE)) {
- verbose(env, "write into map forbidden, value_size=%d off=%d size=%d\n",
- map->value_size, off, size);
- return -EACCES;
- }
- if (type == BPF_READ && !(cap & BPF_MAP_CAN_READ)) {
- verbose(env, "read from map forbidden, value_size=%d off=%d size=%d\n",
- map->value_size, off, size);
- return -EACCES;
- }
- return 0;
- }
- /* check read/write into memory region (e.g., map value, ringbuf sample, etc) */
- static int __check_mem_access(struct bpf_verifier_env *env, int regno,
- int off, int size, u32 mem_size,
- bool zero_size_allowed)
- {
- bool size_ok = size > 0 || (size == 0 && zero_size_allowed);
- struct bpf_reg_state *reg;
- if (off >= 0 && size_ok && (u64)off + size <= mem_size)
- return 0;
- reg = &cur_regs(env)[regno];
- switch (reg->type) {
- case PTR_TO_MAP_VALUE:
- verbose(env, "invalid access to map value, value_size=%d off=%d size=%d\n",
- mem_size, off, size);
- break;
- case PTR_TO_PACKET:
- case PTR_TO_PACKET_META:
- case PTR_TO_PACKET_END:
- verbose(env, "invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
- off, size, regno, reg->id, off, mem_size);
- break;
- case PTR_TO_MEM:
- default:
- verbose(env, "invalid access to memory, mem_size=%u off=%d size=%d\n",
- mem_size, off, size);
- }
- return -EACCES;
- }
- /* check read/write into a memory region with possible variable offset */
- static int check_mem_region_access(struct bpf_verifier_env *env, u32 regno,
- int off, int size, u32 mem_size,
- bool zero_size_allowed)
- {
- struct bpf_verifier_state *vstate = env->cur_state;
- struct bpf_func_state *state = vstate->frame[vstate->curframe];
- struct bpf_reg_state *reg = &state->regs[regno];
- int err;
- /* We may have adjusted the register pointing to memory region, so we
- * need to try adding each of min_value and max_value to off
- * to make sure our theoretical access will be safe.
- */
- if (env->log.level & BPF_LOG_LEVEL)
- print_verifier_state(env, state);
- /* The minimum value is only important with signed
- * comparisons where we can't assume the floor of a
- * value is 0. If we are using signed variables for our
- * index'es we need to make sure that whatever we use
- * will have a set floor within our range.
- */
- if (reg->smin_value < 0 &&
- (reg->smin_value == S64_MIN ||
- (off + reg->smin_value != (s64)(s32)(off + reg->smin_value)) ||
- reg->smin_value + off < 0)) {
- verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
- regno);
- return -EACCES;
- }
- err = __check_mem_access(env, regno, reg->smin_value + off, size,
- mem_size, zero_size_allowed);
- if (err) {
- verbose(env, "R%d min value is outside of the allowed memory range\n",
- regno);
- return err;
- }
- /* If we haven't set a max value then we need to bail since we can't be
- * sure we won't do bad things.
- * If reg->umax_value + off could overflow, treat that as unbounded too.
- */
- if (reg->umax_value >= BPF_MAX_VAR_OFF) {
- verbose(env, "R%d unbounded memory access, make sure to bounds check any such access\n",
- regno);
- return -EACCES;
- }
- err = __check_mem_access(env, regno, reg->umax_value + off, size,
- mem_size, zero_size_allowed);
- if (err) {
- verbose(env, "R%d max value is outside of the allowed memory range\n",
- regno);
- return err;
- }
- return 0;
- }
- /* check read/write into a map element with possible variable offset */
- static int check_map_access(struct bpf_verifier_env *env, u32 regno,
- int off, int size, bool zero_size_allowed)
- {
- struct bpf_verifier_state *vstate = env->cur_state;
- struct bpf_func_state *state = vstate->frame[vstate->curframe];
- struct bpf_reg_state *reg = &state->regs[regno];
- struct bpf_map *map = reg->map_ptr;
- int err;
- err = check_mem_region_access(env, regno, off, size, map->value_size,
- zero_size_allowed);
- if (err)
- return err;
- if (map_value_has_spin_lock(map)) {
- u32 lock = map->spin_lock_off;
- /* if any part of struct bpf_spin_lock can be touched by
- * load/store reject this program.
- * To check that [x1, x2) overlaps with [y1, y2)
- * it is sufficient to check x1 < y2 && y1 < x2.
- */
- if (reg->smin_value + off < lock + sizeof(struct bpf_spin_lock) &&
- lock < reg->umax_value + off + size) {
- verbose(env, "bpf_spin_lock cannot be accessed directly by load/store\n");
- return -EACCES;
- }
- }
- return err;
- }
- #define MAX_PACKET_OFF 0xffff
- static enum bpf_prog_type resolve_prog_type(struct bpf_prog *prog)
- {
- return prog->aux->dst_prog ? prog->aux->dst_prog->type : prog->type;
- }
- static bool may_access_direct_pkt_data(struct bpf_verifier_env *env,
- const struct bpf_call_arg_meta *meta,
- enum bpf_access_type t)
- {
- enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
- switch (prog_type) {
- /* Program types only with direct read access go here! */
- case BPF_PROG_TYPE_LWT_IN:
- case BPF_PROG_TYPE_LWT_OUT:
- case BPF_PROG_TYPE_LWT_SEG6LOCAL:
- case BPF_PROG_TYPE_SK_REUSEPORT:
- case BPF_PROG_TYPE_FLOW_DISSECTOR:
- case BPF_PROG_TYPE_CGROUP_SKB:
- if (t == BPF_WRITE)
- return false;
- fallthrough;
- /* Program types with direct read + write access go here! */
- case BPF_PROG_TYPE_SCHED_CLS:
- case BPF_PROG_TYPE_SCHED_ACT:
- case BPF_PROG_TYPE_XDP:
- case BPF_PROG_TYPE_LWT_XMIT:
- case BPF_PROG_TYPE_SK_SKB:
- case BPF_PROG_TYPE_SK_MSG:
- if (meta)
- return meta->pkt_access;
- env->seen_direct_write = true;
- return true;
- case BPF_PROG_TYPE_CGROUP_SOCKOPT:
- if (t == BPF_WRITE)
- env->seen_direct_write = true;
- return true;
- default:
- return false;
- }
- }
- static int check_packet_access(struct bpf_verifier_env *env, u32 regno, int off,
- int size, bool zero_size_allowed)
- {
- struct bpf_reg_state *regs = cur_regs(env);
- struct bpf_reg_state *reg = ®s[regno];
- int err;
- /* We may have added a variable offset to the packet pointer; but any
- * reg->range we have comes after that. We are only checking the fixed
- * offset.
- */
- /* We don't allow negative numbers, because we aren't tracking enough
- * detail to prove they're safe.
- */
- if (reg->smin_value < 0) {
- verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
- regno);
- return -EACCES;
- }
- err = __check_mem_access(env, regno, off, size, reg->range,
- zero_size_allowed);
- if (err) {
- verbose(env, "R%d offset is outside of the packet\n", regno);
- return err;
- }
- /* __check_mem_access has made sure "off + size - 1" is within u16.
- * reg->umax_value can't be bigger than MAX_PACKET_OFF which is 0xffff,
- * otherwise find_good_pkt_pointers would have refused to set range info
- * that __check_mem_access would have rejected this pkt access.
- * Therefore, "off + reg->umax_value + size - 1" won't overflow u32.
- */
- env->prog->aux->max_pkt_offset =
- max_t(u32, env->prog->aux->max_pkt_offset,
- off + reg->umax_value + size - 1);
- return err;
- }
- /* check access to 'struct bpf_context' fields. Supports fixed offsets only */
- static int check_ctx_access(struct bpf_verifier_env *env, int insn_idx, int off, int size,
- enum bpf_access_type t, enum bpf_reg_type *reg_type,
- u32 *btf_id)
- {
- struct bpf_insn_access_aux info = {
- .reg_type = *reg_type,
- .log = &env->log,
- };
- if (env->ops->is_valid_access &&
- env->ops->is_valid_access(off, size, t, env->prog, &info)) {
- /* A non zero info.ctx_field_size indicates that this field is a
- * candidate for later verifier transformation to load the whole
- * field and then apply a mask when accessed with a narrower
- * access than actual ctx access size. A zero info.ctx_field_size
- * will only allow for whole field access and rejects any other
- * type of narrower access.
- */
- *reg_type = info.reg_type;
- if (*reg_type == PTR_TO_BTF_ID || *reg_type == PTR_TO_BTF_ID_OR_NULL)
- *btf_id = info.btf_id;
- else
- env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size;
- /* remember the offset of last byte accessed in ctx */
- if (env->prog->aux->max_ctx_offset < off + size)
- env->prog->aux->max_ctx_offset = off + size;
- return 0;
- }
- verbose(env, "invalid bpf_context access off=%d size=%d\n", off, size);
- return -EACCES;
- }
- static int check_flow_keys_access(struct bpf_verifier_env *env, int off,
- int size)
- {
- if (size < 0 || off < 0 ||
- (u64)off + size > sizeof(struct bpf_flow_keys)) {
- verbose(env, "invalid access to flow keys off=%d size=%d\n",
- off, size);
- return -EACCES;
- }
- return 0;
- }
- static int check_sock_access(struct bpf_verifier_env *env, int insn_idx,
- u32 regno, int off, int size,
- enum bpf_access_type t)
- {
- struct bpf_reg_state *regs = cur_regs(env);
- struct bpf_reg_state *reg = ®s[regno];
- struct bpf_insn_access_aux info = {};
- bool valid;
- if (reg->smin_value < 0) {
- verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n",
- regno);
- return -EACCES;
- }
- switch (reg->type) {
- case PTR_TO_SOCK_COMMON:
- valid = bpf_sock_common_is_valid_access(off, size, t, &info);
- break;
- case PTR_TO_SOCKET:
- valid = bpf_sock_is_valid_access(off, size, t, &info);
- break;
- case PTR_TO_TCP_SOCK:
- valid = bpf_tcp_sock_is_valid_access(off, size, t, &info);
- break;
- case PTR_TO_XDP_SOCK:
- valid = bpf_xdp_sock_is_valid_access(off, size, t, &info);
- break;
- default:
- valid = false;
- }
- if (valid) {
- env->insn_aux_data[insn_idx].ctx_field_size =
- info.ctx_field_size;
- return 0;
- }
- verbose(env, "R%d invalid %s access off=%d size=%d\n",
- regno, reg_type_str[reg->type], off, size);
- return -EACCES;
- }
- static bool is_pointer_value(struct bpf_verifier_env *env, int regno)
- {
- return __is_pointer_value(env->allow_ptr_leaks, reg_state(env, regno));
- }
- static bool is_ctx_reg(struct bpf_verifier_env *env, int regno)
- {
- const struct bpf_reg_state *reg = reg_state(env, regno);
- return reg->type == PTR_TO_CTX;
- }
- static bool is_sk_reg(struct bpf_verifier_env *env, int regno)
- {
- const struct bpf_reg_state *reg = reg_state(env, regno);
- return type_is_sk_pointer(reg->type);
- }
- static bool is_pkt_reg(struct bpf_verifier_env *env, int regno)
- {
- const struct bpf_reg_state *reg = reg_state(env, regno);
- return type_is_pkt_pointer(reg->type);
- }
- static bool is_flow_key_reg(struct bpf_verifier_env *env, int regno)
- {
- const struct bpf_reg_state *reg = reg_state(env, regno);
- /* Separate to is_ctx_reg() since we still want to allow BPF_ST here. */
- return reg->type == PTR_TO_FLOW_KEYS;
- }
- static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
- const struct bpf_reg_state *reg,
- int off, int size, bool strict)
- {
- struct tnum reg_off;
- int ip_align;
- /* Byte size accesses are always allowed. */
- if (!strict || size == 1)
- return 0;
- /* For platforms that do not have a Kconfig enabling
- * CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the value of
- * NET_IP_ALIGN is universally set to '2'. And on platforms
- * that do set CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS, we get
- * to this code only in strict mode where we want to emulate
- * the NET_IP_ALIGN==2 checking. Therefore use an
- * unconditional IP align value of '2'.
- */
- ip_align = 2;
- reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off));
- if (!tnum_is_aligned(reg_off, size)) {
- char tn_buf[48];
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env,
- "misaligned packet access off %d+%s+%d+%d size %d\n",
- ip_align, tn_buf, reg->off, off, size);
- return -EACCES;
- }
- return 0;
- }
- static int check_generic_ptr_alignment(struct bpf_verifier_env *env,
- const struct bpf_reg_state *reg,
- const char *pointer_desc,
- int off, int size, bool strict)
- {
- struct tnum reg_off;
- /* Byte size accesses are always allowed. */
- if (!strict || size == 1)
- return 0;
- reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off));
- if (!tnum_is_aligned(reg_off, size)) {
- char tn_buf[48];
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env, "misaligned %saccess off %s+%d+%d size %d\n",
- pointer_desc, tn_buf, reg->off, off, size);
- return -EACCES;
- }
- return 0;
- }
- static int check_ptr_alignment(struct bpf_verifier_env *env,
- const struct bpf_reg_state *reg, int off,
- int size, bool strict_alignment_once)
- {
- bool strict = env->strict_alignment || strict_alignment_once;
- const char *pointer_desc = "";
- switch (reg->type) {
- case PTR_TO_PACKET:
- case PTR_TO_PACKET_META:
- /* Special case, because of NET_IP_ALIGN. Given metadata sits
- * right in front, treat it the very same way.
- */
- return check_pkt_ptr_alignment(env, reg, off, size, strict);
- case PTR_TO_FLOW_KEYS:
- pointer_desc = "flow keys ";
- break;
- case PTR_TO_MAP_VALUE:
- pointer_desc = "value ";
- break;
- case PTR_TO_CTX:
- pointer_desc = "context ";
- break;
- case PTR_TO_STACK:
- pointer_desc = "stack ";
- /* The stack spill tracking logic in check_stack_write_fixed_off()
- * and check_stack_read_fixed_off() relies on stack accesses being
- * aligned.
- */
- strict = true;
- break;
- case PTR_TO_SOCKET:
- pointer_desc = "sock ";
- break;
- case PTR_TO_SOCK_COMMON:
- pointer_desc = "sock_common ";
- break;
- case PTR_TO_TCP_SOCK:
- pointer_desc = "tcp_sock ";
- break;
- case PTR_TO_XDP_SOCK:
- pointer_desc = "xdp_sock ";
- break;
- default:
- break;
- }
- return check_generic_ptr_alignment(env, reg, pointer_desc, off, size,
- strict);
- }
- static int update_stack_depth(struct bpf_verifier_env *env,
- const struct bpf_func_state *func,
- int off)
- {
- u16 stack = env->subprog_info[func->subprogno].stack_depth;
- if (stack >= -off)
- return 0;
- /* update known max for given subprogram */
- env->subprog_info[func->subprogno].stack_depth = -off;
- return 0;
- }
- /* starting from main bpf function walk all instructions of the function
- * and recursively walk all callees that given function can call.
- * Ignore jump and exit insns.
- * Since recursion is prevented by check_cfg() this algorithm
- * only needs a local stack of MAX_CALL_FRAMES to remember callsites
- */
- static int check_max_stack_depth(struct bpf_verifier_env *env)
- {
- int depth = 0, frame = 0, idx = 0, i = 0, subprog_end;
- struct bpf_subprog_info *subprog = env->subprog_info;
- struct bpf_insn *insn = env->prog->insnsi;
- bool tail_call_reachable = false;
- int ret_insn[MAX_CALL_FRAMES];
- int ret_prog[MAX_CALL_FRAMES];
- int j;
- process_func:
- /* protect against potential stack overflow that might happen when
- * bpf2bpf calls get combined with tailcalls. Limit the caller's stack
- * depth for such case down to 256 so that the worst case scenario
- * would result in 8k stack size (32 which is tailcall limit * 256 =
- * 8k).
- *
- * To get the idea what might happen, see an example:
- * func1 -> sub rsp, 128
- * subfunc1 -> sub rsp, 256
- * tailcall1 -> add rsp, 256
- * func2 -> sub rsp, 192 (total stack size = 128 + 192 = 320)
- * subfunc2 -> sub rsp, 64
- * subfunc22 -> sub rsp, 128
- * tailcall2 -> add rsp, 128
- * func3 -> sub rsp, 32 (total stack size 128 + 192 + 64 + 32 = 416)
- *
- * tailcall will unwind the current stack frame but it will not get rid
- * of caller's stack as shown on the example above.
- */
- if (idx && subprog[idx].has_tail_call && depth >= 256) {
- verbose(env,
- "tail_calls are not allowed when call stack of previous frames is %d bytes. Too large\n",
- depth);
- return -EACCES;
- }
- /* round up to 32-bytes, since this is granularity
- * of interpreter stack size
- */
- depth += round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);
- if (depth > MAX_BPF_STACK) {
- verbose(env, "combined stack size of %d calls is %d. Too large\n",
- frame + 1, depth);
- return -EACCES;
- }
- continue_func:
- subprog_end = subprog[idx + 1].start;
- for (; i < subprog_end; i++) {
- if (insn[i].code != (BPF_JMP | BPF_CALL))
- continue;
- if (insn[i].src_reg != BPF_PSEUDO_CALL)
- continue;
- /* remember insn and function to return to */
- ret_insn[frame] = i + 1;
- ret_prog[frame] = idx;
- /* find the callee */
- i = i + insn[i].imm + 1;
- idx = find_subprog(env, i);
- if (idx < 0) {
- WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
- i);
- return -EFAULT;
- }
- if (subprog[idx].has_tail_call)
- tail_call_reachable = true;
- frame++;
- if (frame >= MAX_CALL_FRAMES) {
- verbose(env, "the call stack of %d frames is too deep !\n",
- frame);
- return -E2BIG;
- }
- goto process_func;
- }
- /* if tail call got detected across bpf2bpf calls then mark each of the
- * currently present subprog frames as tail call reachable subprogs;
- * this info will be utilized by JIT so that we will be preserving the
- * tail call counter throughout bpf2bpf calls combined with tailcalls
- */
- if (tail_call_reachable)
- for (j = 0; j < frame; j++)
- subprog[ret_prog[j]].tail_call_reachable = true;
- if (subprog[0].tail_call_reachable)
- env->prog->aux->tail_call_reachable = true;
- /* end of for() loop means the last insn of the 'subprog'
- * was reached. Doesn't matter whether it was JA or EXIT
- */
- if (frame == 0)
- return 0;
- depth -= round_up(max_t(u32, subprog[idx].stack_depth, 1), 32);
- frame--;
- i = ret_insn[frame];
- idx = ret_prog[frame];
- goto continue_func;
- }
- #ifndef CONFIG_BPF_JIT_ALWAYS_ON
- static int get_callee_stack_depth(struct bpf_verifier_env *env,
- const struct bpf_insn *insn, int idx)
- {
- int start = idx + insn->imm + 1, subprog;
- subprog = find_subprog(env, start);
- if (subprog < 0) {
- WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
- start);
- return -EFAULT;
- }
- return env->subprog_info[subprog].stack_depth;
- }
- #endif
- int check_ctx_reg(struct bpf_verifier_env *env,
- const struct bpf_reg_state *reg, int regno)
- {
- /* Access to ctx or passing it to a helper is only allowed in
- * its original, unmodified form.
- */
- if (reg->off) {
- verbose(env, "dereference of modified ctx ptr R%d off=%d disallowed\n",
- regno, reg->off);
- return -EACCES;
- }
- if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
- char tn_buf[48];
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env, "variable ctx access var_off=%s disallowed\n", tn_buf);
- return -EACCES;
- }
- return 0;
- }
- static int __check_buffer_access(struct bpf_verifier_env *env,
- const char *buf_info,
- const struct bpf_reg_state *reg,
- int regno, int off, int size)
- {
- if (off < 0) {
- verbose(env,
- "R%d invalid %s buffer access: off=%d, size=%d\n",
- regno, buf_info, off, size);
- return -EACCES;
- }
- if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
- char tn_buf[48];
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env,
- "R%d invalid variable buffer offset: off=%d, var_off=%s\n",
- regno, off, tn_buf);
- return -EACCES;
- }
- return 0;
- }
- static int check_tp_buffer_access(struct bpf_verifier_env *env,
- const struct bpf_reg_state *reg,
- int regno, int off, int size)
- {
- int err;
- err = __check_buffer_access(env, "tracepoint", reg, regno, off, size);
- if (err)
- return err;
- if (off + size > env->prog->aux->max_tp_access)
- env->prog->aux->max_tp_access = off + size;
- return 0;
- }
- static int check_buffer_access(struct bpf_verifier_env *env,
- const struct bpf_reg_state *reg,
- int regno, int off, int size,
- bool zero_size_allowed,
- const char *buf_info,
- u32 *max_access)
- {
- int err;
- err = __check_buffer_access(env, buf_info, reg, regno, off, size);
- if (err)
- return err;
- if (off + size > *max_access)
- *max_access = off + size;
- return 0;
- }
- /* BPF architecture zero extends alu32 ops into 64-bit registesr */
- static void zext_32_to_64(struct bpf_reg_state *reg)
- {
- reg->var_off = tnum_subreg(reg->var_off);
- __reg_assign_32_into_64(reg);
- }
- /* truncate register to smaller size (in bytes)
- * must be called with size < BPF_REG_SIZE
- */
- static void coerce_reg_to_size(struct bpf_reg_state *reg, int size)
- {
- u64 mask;
- /* clear high bits in bit representation */
- reg->var_off = tnum_cast(reg->var_off, size);
- /* fix arithmetic bounds */
- mask = ((u64)1 << (size * 8)) - 1;
- if ((reg->umin_value & ~mask) == (reg->umax_value & ~mask)) {
- reg->umin_value &= mask;
- reg->umax_value &= mask;
- } else {
- reg->umin_value = 0;
- reg->umax_value = mask;
- }
- reg->smin_value = reg->umin_value;
- reg->smax_value = reg->umax_value;
- /* If size is smaller than 32bit register the 32bit register
- * values are also truncated so we push 64-bit bounds into
- * 32-bit bounds. Above were truncated < 32-bits already.
- */
- if (size >= 4)
- return;
- __reg_combine_64_into_32(reg);
- }
- static bool bpf_map_is_rdonly(const struct bpf_map *map)
- {
- /* A map is considered read-only if the following condition are true:
- *
- * 1) BPF program side cannot change any of the map content. The
- * BPF_F_RDONLY_PROG flag is throughout the lifetime of a map
- * and was set at map creation time.
- * 2) The map value(s) have been initialized from user space by a
- * loader and then "frozen", such that no new map update/delete
- * operations from syscall side are possible for the rest of
- * the map's lifetime from that point onwards.
- * 3) Any parallel/pending map update/delete operations from syscall
- * side have been completed. Only after that point, it's safe to
- * assume that map value(s) are immutable.
- */
- return (map->map_flags & BPF_F_RDONLY_PROG) &&
- READ_ONCE(map->frozen) &&
- !bpf_map_write_active(map);
- }
- static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val)
- {
- void *ptr;
- u64 addr;
- int err;
- err = map->ops->map_direct_value_addr(map, &addr, off);
- if (err)
- return err;
- ptr = (void *)(long)addr + off;
- switch (size) {
- case sizeof(u8):
- *val = (u64)*(u8 *)ptr;
- break;
- case sizeof(u16):
- *val = (u64)*(u16 *)ptr;
- break;
- case sizeof(u32):
- *val = (u64)*(u32 *)ptr;
- break;
- case sizeof(u64):
- *val = *(u64 *)ptr;
- break;
- default:
- return -EINVAL;
- }
- return 0;
- }
- static int check_ptr_to_btf_access(struct bpf_verifier_env *env,
- struct bpf_reg_state *regs,
- int regno, int off, int size,
- enum bpf_access_type atype,
- int value_regno)
- {
- struct bpf_reg_state *reg = regs + regno;
- const struct btf_type *t = btf_type_by_id(btf_vmlinux, reg->btf_id);
- const char *tname = btf_name_by_offset(btf_vmlinux, t->name_off);
- u32 btf_id;
- int ret;
- if (off < 0) {
- verbose(env,
- "R%d is ptr_%s invalid negative access: off=%d\n",
- regno, tname, off);
- return -EACCES;
- }
- if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
- char tn_buf[48];
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env,
- "R%d is ptr_%s invalid variable offset: off=%d, var_off=%s\n",
- regno, tname, off, tn_buf);
- return -EACCES;
- }
- if (env->ops->btf_struct_access) {
- ret = env->ops->btf_struct_access(&env->log, t, off, size,
- atype, &btf_id);
- } else {
- if (atype != BPF_READ) {
- verbose(env, "only read is supported\n");
- return -EACCES;
- }
- ret = btf_struct_access(&env->log, t, off, size, atype,
- &btf_id);
- }
- if (ret < 0)
- return ret;
- if (atype == BPF_READ && value_regno >= 0)
- mark_btf_ld_reg(env, regs, value_regno, ret, btf_id);
- return 0;
- }
- static int check_ptr_to_map_access(struct bpf_verifier_env *env,
- struct bpf_reg_state *regs,
- int regno, int off, int size,
- enum bpf_access_type atype,
- int value_regno)
- {
- struct bpf_reg_state *reg = regs + regno;
- struct bpf_map *map = reg->map_ptr;
- const struct btf_type *t;
- const char *tname;
- u32 btf_id;
- int ret;
- if (!btf_vmlinux) {
- verbose(env, "map_ptr access not supported without CONFIG_DEBUG_INFO_BTF\n");
- return -ENOTSUPP;
- }
- if (!map->ops->map_btf_id || !*map->ops->map_btf_id) {
- verbose(env, "map_ptr access not supported for map type %d\n",
- map->map_type);
- return -ENOTSUPP;
- }
- t = btf_type_by_id(btf_vmlinux, *map->ops->map_btf_id);
- tname = btf_name_by_offset(btf_vmlinux, t->name_off);
- if (!env->allow_ptr_to_map_access) {
- verbose(env,
- "%s access is allowed only to CAP_PERFMON and CAP_SYS_ADMIN\n",
- tname);
- return -EPERM;
- }
- if (off < 0) {
- verbose(env, "R%d is %s invalid negative access: off=%d\n",
- regno, tname, off);
- return -EACCES;
- }
- if (atype != BPF_READ) {
- verbose(env, "only read from %s is supported\n", tname);
- return -EACCES;
- }
- ret = btf_struct_access(&env->log, t, off, size, atype, &btf_id);
- if (ret < 0)
- return ret;
- if (value_regno >= 0)
- mark_btf_ld_reg(env, regs, value_regno, ret, btf_id);
- return 0;
- }
- /* Check that the stack access at the given offset is within bounds. The
- * maximum valid offset is -1.
- *
- * The minimum valid offset is -MAX_BPF_STACK for writes, and
- * -state->allocated_stack for reads.
- */
- static int check_stack_slot_within_bounds(int off,
- struct bpf_func_state *state,
- enum bpf_access_type t)
- {
- int min_valid_off;
- if (t == BPF_WRITE)
- min_valid_off = -MAX_BPF_STACK;
- else
- min_valid_off = -state->allocated_stack;
- if (off < min_valid_off || off > -1)
- return -EACCES;
- return 0;
- }
- /* Check that the stack access at 'regno + off' falls within the maximum stack
- * bounds.
- *
- * 'off' includes `regno->offset`, but not its dynamic part (if any).
- */
- static int check_stack_access_within_bounds(
- struct bpf_verifier_env *env,
- int regno, int off, int access_size,
- enum stack_access_src src, enum bpf_access_type type)
- {
- struct bpf_reg_state *regs = cur_regs(env);
- struct bpf_reg_state *reg = regs + regno;
- struct bpf_func_state *state = func(env, reg);
- int min_off, max_off;
- int err;
- char *err_extra;
- if (src == ACCESS_HELPER)
- /* We don't know if helpers are reading or writing (or both). */
- err_extra = " indirect access to";
- else if (type == BPF_READ)
- err_extra = " read from";
- else
- err_extra = " write to";
- if (tnum_is_const(reg->var_off)) {
- min_off = reg->var_off.value + off;
- if (access_size > 0)
- max_off = min_off + access_size - 1;
- else
- max_off = min_off;
- } else {
- if (reg->smax_value >= BPF_MAX_VAR_OFF ||
- reg->smin_value <= -BPF_MAX_VAR_OFF) {
- verbose(env, "invalid unbounded variable-offset%s stack R%d\n",
- err_extra, regno);
- return -EACCES;
- }
- min_off = reg->smin_value + off;
- if (access_size > 0)
- max_off = reg->smax_value + off + access_size - 1;
- else
- max_off = min_off;
- }
- err = check_stack_slot_within_bounds(min_off, state, type);
- if (!err)
- err = check_stack_slot_within_bounds(max_off, state, type);
- if (err) {
- if (tnum_is_const(reg->var_off)) {
- verbose(env, "invalid%s stack R%d off=%d size=%d\n",
- err_extra, regno, off, access_size);
- } else {
- char tn_buf[48];
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env, "invalid variable-offset%s stack R%d var_off=%s size=%d\n",
- err_extra, regno, tn_buf, access_size);
- }
- }
- return err;
- }
- /* check whether memory at (regno + off) is accessible for t = (read | write)
- * if t==write, value_regno is a register which value is stored into memory
- * if t==read, value_regno is a register which will receive the value from memory
- * if t==write && value_regno==-1, some unknown value is stored into memory
- * if t==read && value_regno==-1, don't care what we read from memory
- */
- static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regno,
- int off, int bpf_size, enum bpf_access_type t,
- int value_regno, bool strict_alignment_once)
- {
- struct bpf_reg_state *regs = cur_regs(env);
- struct bpf_reg_state *reg = regs + regno;
- struct bpf_func_state *state;
- int size, err = 0;
- size = bpf_size_to_bytes(bpf_size);
- if (size < 0)
- return size;
- /* alignment checks will add in reg->off themselves */
- err = check_ptr_alignment(env, reg, off, size, strict_alignment_once);
- if (err)
- return err;
- /* for access checks, reg->off is just part of off */
- off += reg->off;
- if (reg->type == PTR_TO_MAP_VALUE) {
- if (t == BPF_WRITE && value_regno >= 0 &&
- is_pointer_value(env, value_regno)) {
- verbose(env, "R%d leaks addr into map\n", value_regno);
- return -EACCES;
- }
- err = check_map_access_type(env, regno, off, size, t);
- if (err)
- return err;
- err = check_map_access(env, regno, off, size, false);
- if (!err && t == BPF_READ && value_regno >= 0) {
- struct bpf_map *map = reg->map_ptr;
- /* if map is read-only, track its contents as scalars */
- if (tnum_is_const(reg->var_off) &&
- bpf_map_is_rdonly(map) &&
- map->ops->map_direct_value_addr) {
- int map_off = off + reg->var_off.value;
- u64 val = 0;
- err = bpf_map_direct_read(map, map_off, size,
- &val);
- if (err)
- return err;
- regs[value_regno].type = SCALAR_VALUE;
- __mark_reg_known(®s[value_regno], val);
- } else {
- mark_reg_unknown(env, regs, value_regno);
- }
- }
- } else if (reg->type == PTR_TO_MEM) {
- if (t == BPF_WRITE && value_regno >= 0 &&
- is_pointer_value(env, value_regno)) {
- verbose(env, "R%d leaks addr into mem\n", value_regno);
- return -EACCES;
- }
- err = check_mem_region_access(env, regno, off, size,
- reg->mem_size, false);
- if (!err && t == BPF_READ && value_regno >= 0)
- mark_reg_unknown(env, regs, value_regno);
- } else if (reg->type == PTR_TO_CTX) {
- enum bpf_reg_type reg_type = SCALAR_VALUE;
- u32 btf_id = 0;
- if (t == BPF_WRITE && value_regno >= 0 &&
- is_pointer_value(env, value_regno)) {
- verbose(env, "R%d leaks addr into ctx\n", value_regno);
- return -EACCES;
- }
- err = check_ctx_reg(env, reg, regno);
- if (err < 0)
- return err;
- err = check_ctx_access(env, insn_idx, off, size, t, ®_type, &btf_id);
- if (err)
- verbose_linfo(env, insn_idx, "; ");
- if (!err && t == BPF_READ && value_regno >= 0) {
- /* ctx access returns either a scalar, or a
- * PTR_TO_PACKET[_META,_END]. In the latter
- * case, we know the offset is zero.
- */
- if (reg_type == SCALAR_VALUE) {
- mark_reg_unknown(env, regs, value_regno);
- } else {
- mark_reg_known_zero(env, regs,
- value_regno);
- if (reg_type_may_be_null(reg_type))
- regs[value_regno].id = ++env->id_gen;
- /* A load of ctx field could have different
- * actual load size with the one encoded in the
- * insn. When the dst is PTR, it is for sure not
- * a sub-register.
- */
- regs[value_regno].subreg_def = DEF_NOT_SUBREG;
- if (reg_type == PTR_TO_BTF_ID ||
- reg_type == PTR_TO_BTF_ID_OR_NULL)
- regs[value_regno].btf_id = btf_id;
- }
- regs[value_regno].type = reg_type;
- }
- } else if (reg->type == PTR_TO_STACK) {
- /* Basic bounds checks. */
- err = check_stack_access_within_bounds(env, regno, off, size, ACCESS_DIRECT, t);
- if (err)
- return err;
- state = func(env, reg);
- err = update_stack_depth(env, state, off);
- if (err)
- return err;
- if (t == BPF_READ)
- err = check_stack_read(env, regno, off, size,
- value_regno);
- else
- err = check_stack_write(env, regno, off, size,
- value_regno, insn_idx);
- } else if (reg_is_pkt_pointer(reg)) {
- if (t == BPF_WRITE && !may_access_direct_pkt_data(env, NULL, t)) {
- verbose(env, "cannot write into packet\n");
- return -EACCES;
- }
- if (t == BPF_WRITE && value_regno >= 0 &&
- is_pointer_value(env, value_regno)) {
- verbose(env, "R%d leaks addr into packet\n",
- value_regno);
- return -EACCES;
- }
- err = check_packet_access(env, regno, off, size, false);
- if (!err && t == BPF_READ && value_regno >= 0)
- mark_reg_unknown(env, regs, value_regno);
- } else if (reg->type == PTR_TO_FLOW_KEYS) {
- if (t == BPF_WRITE && value_regno >= 0 &&
- is_pointer_value(env, value_regno)) {
- verbose(env, "R%d leaks addr into flow keys\n",
- value_regno);
- return -EACCES;
- }
- err = check_flow_keys_access(env, off, size);
- if (!err && t == BPF_READ && value_regno >= 0)
- mark_reg_unknown(env, regs, value_regno);
- } else if (type_is_sk_pointer(reg->type)) {
- if (t == BPF_WRITE) {
- verbose(env, "R%d cannot write into %s\n",
- regno, reg_type_str[reg->type]);
- return -EACCES;
- }
- err = check_sock_access(env, insn_idx, regno, off, size, t);
- if (!err && value_regno >= 0)
- mark_reg_unknown(env, regs, value_regno);
- } else if (reg->type == PTR_TO_TP_BUFFER) {
- err = check_tp_buffer_access(env, reg, regno, off, size);
- if (!err && t == BPF_READ && value_regno >= 0)
- mark_reg_unknown(env, regs, value_regno);
- } else if (reg->type == PTR_TO_BTF_ID) {
- err = check_ptr_to_btf_access(env, regs, regno, off, size, t,
- value_regno);
- } else if (reg->type == CONST_PTR_TO_MAP) {
- err = check_ptr_to_map_access(env, regs, regno, off, size, t,
- value_regno);
- } else if (reg->type == PTR_TO_RDONLY_BUF) {
- if (t == BPF_WRITE) {
- verbose(env, "R%d cannot write into %s\n",
- regno, reg_type_str[reg->type]);
- return -EACCES;
- }
- err = check_buffer_access(env, reg, regno, off, size, false,
- "rdonly",
- &env->prog->aux->max_rdonly_access);
- if (!err && value_regno >= 0)
- mark_reg_unknown(env, regs, value_regno);
- } else if (reg->type == PTR_TO_RDWR_BUF) {
- err = check_buffer_access(env, reg, regno, off, size, false,
- "rdwr",
- &env->prog->aux->max_rdwr_access);
- if (!err && t == BPF_READ && value_regno >= 0)
- mark_reg_unknown(env, regs, value_regno);
- } else {
- verbose(env, "R%d invalid mem access '%s'\n", regno,
- reg_type_str[reg->type]);
- return -EACCES;
- }
- if (!err && size < BPF_REG_SIZE && value_regno >= 0 && t == BPF_READ &&
- regs[value_regno].type == SCALAR_VALUE) {
- /* b/h/w load zero-extends, mark upper bits as known 0 */
- coerce_reg_to_size(®s[value_regno], size);
- }
- return err;
- }
- static int check_xadd(struct bpf_verifier_env *env, int insn_idx, struct bpf_insn *insn)
- {
- int err;
- if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) ||
- insn->imm != 0) {
- verbose(env, "BPF_XADD uses reserved fields\n");
- return -EINVAL;
- }
- /* check src1 operand */
- err = check_reg_arg(env, insn->src_reg, SRC_OP);
- if (err)
- return err;
- /* check src2 operand */
- err = check_reg_arg(env, insn->dst_reg, SRC_OP);
- if (err)
- return err;
- if (is_pointer_value(env, insn->src_reg)) {
- verbose(env, "R%d leaks addr into mem\n", insn->src_reg);
- return -EACCES;
- }
- if (is_ctx_reg(env, insn->dst_reg) ||
- is_pkt_reg(env, insn->dst_reg) ||
- is_flow_key_reg(env, insn->dst_reg) ||
- is_sk_reg(env, insn->dst_reg)) {
- verbose(env, "BPF_XADD stores into R%d %s is not allowed\n",
- insn->dst_reg,
- reg_type_str[reg_state(env, insn->dst_reg)->type]);
- return -EACCES;
- }
- /* check whether atomic_add can read the memory */
- err = check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
- BPF_SIZE(insn->code), BPF_READ, -1, true);
- if (err)
- return err;
- /* check whether atomic_add can write into the same memory */
- return check_mem_access(env, insn_idx, insn->dst_reg, insn->off,
- BPF_SIZE(insn->code), BPF_WRITE, -1, true);
- }
- /* When register 'regno' is used to read the stack (either directly or through
- * a helper function) make sure that it's within stack boundary and, depending
- * on the access type, that all elements of the stack are initialized.
- *
- * 'off' includes 'regno->off', but not its dynamic part (if any).
- *
- * All registers that have been spilled on the stack in the slots within the
- * read offsets are marked as read.
- */
- static int check_stack_range_initialized(
- struct bpf_verifier_env *env, int regno, int off,
- int access_size, bool zero_size_allowed,
- enum stack_access_src type, struct bpf_call_arg_meta *meta)
- {
- struct bpf_reg_state *reg = reg_state(env, regno);
- struct bpf_func_state *state = func(env, reg);
- int err, min_off, max_off, i, j, slot, spi;
- char *err_extra = type == ACCESS_HELPER ? " indirect" : "";
- enum bpf_access_type bounds_check_type;
- /* Some accesses can write anything into the stack, others are
- * read-only.
- */
- bool clobber = false;
- if (access_size == 0 && !zero_size_allowed) {
- verbose(env, "invalid zero-sized read\n");
- return -EACCES;
- }
- if (type == ACCESS_HELPER) {
- /* The bounds checks for writes are more permissive than for
- * reads. However, if raw_mode is not set, we'll do extra
- * checks below.
- */
- bounds_check_type = BPF_WRITE;
- clobber = true;
- } else {
- bounds_check_type = BPF_READ;
- }
- err = check_stack_access_within_bounds(env, regno, off, access_size,
- type, bounds_check_type);
- if (err)
- return err;
- if (tnum_is_const(reg->var_off)) {
- min_off = max_off = reg->var_off.value + off;
- } else {
- /* Variable offset is prohibited for unprivileged mode for
- * simplicity since it requires corresponding support in
- * Spectre masking for stack ALU.
- * See also retrieve_ptr_limit().
- */
- if (!env->bypass_spec_v1) {
- char tn_buf[48];
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env, "R%d%s variable offset stack access prohibited for !root, var_off=%s\n",
- regno, err_extra, tn_buf);
- return -EACCES;
- }
- /* Only initialized buffer on stack is allowed to be accessed
- * with variable offset. With uninitialized buffer it's hard to
- * guarantee that whole memory is marked as initialized on
- * helper return since specific bounds are unknown what may
- * cause uninitialized stack leaking.
- */
- if (meta && meta->raw_mode)
- meta = NULL;
- min_off = reg->smin_value + off;
- max_off = reg->smax_value + off;
- }
- if (meta && meta->raw_mode) {
- meta->access_size = access_size;
- meta->regno = regno;
- return 0;
- }
- for (i = min_off; i < max_off + access_size; i++) {
- u8 *stype;
- slot = -i - 1;
- spi = slot / BPF_REG_SIZE;
- if (state->allocated_stack <= slot)
- goto err;
- stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE];
- if (*stype == STACK_MISC)
- goto mark;
- if (*stype == STACK_ZERO) {
- if (clobber) {
- /* helper can write anything into the stack */
- *stype = STACK_MISC;
- }
- goto mark;
- }
- if (state->stack[spi].slot_type[0] == STACK_SPILL &&
- state->stack[spi].spilled_ptr.type == PTR_TO_BTF_ID)
- goto mark;
- if (state->stack[spi].slot_type[0] == STACK_SPILL &&
- (state->stack[spi].spilled_ptr.type == SCALAR_VALUE ||
- env->allow_ptr_leaks)) {
- if (clobber) {
- __mark_reg_unknown(env, &state->stack[spi].spilled_ptr);
- for (j = 0; j < BPF_REG_SIZE; j++)
- state->stack[spi].slot_type[j] = STACK_MISC;
- }
- goto mark;
- }
- err:
- if (tnum_is_const(reg->var_off)) {
- verbose(env, "invalid%s read from stack R%d off %d+%d size %d\n",
- err_extra, regno, min_off, i - min_off, access_size);
- } else {
- char tn_buf[48];
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env, "invalid%s read from stack R%d var_off %s+%d size %d\n",
- err_extra, regno, tn_buf, i - min_off, access_size);
- }
- return -EACCES;
- mark:
- /* reading any byte out of 8-byte 'spill_slot' will cause
- * the whole slot to be marked as 'read'
- */
- mark_reg_read(env, &state->stack[spi].spilled_ptr,
- state->stack[spi].spilled_ptr.parent,
- REG_LIVE_READ64);
- }
- return update_stack_depth(env, state, min_off);
- }
- static int check_helper_mem_access(struct bpf_verifier_env *env, int regno,
- int access_size, bool zero_size_allowed,
- struct bpf_call_arg_meta *meta)
- {
- struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
- switch (reg->type) {
- case PTR_TO_PACKET:
- case PTR_TO_PACKET_META:
- return check_packet_access(env, regno, reg->off, access_size,
- zero_size_allowed);
- case PTR_TO_MAP_VALUE:
- if (check_map_access_type(env, regno, reg->off, access_size,
- meta && meta->raw_mode ? BPF_WRITE :
- BPF_READ))
- return -EACCES;
- return check_map_access(env, regno, reg->off, access_size,
- zero_size_allowed);
- case PTR_TO_MEM:
- return check_mem_region_access(env, regno, reg->off,
- access_size, reg->mem_size,
- zero_size_allowed);
- case PTR_TO_RDONLY_BUF:
- if (meta && meta->raw_mode)
- return -EACCES;
- return check_buffer_access(env, reg, regno, reg->off,
- access_size, zero_size_allowed,
- "rdonly",
- &env->prog->aux->max_rdonly_access);
- case PTR_TO_RDWR_BUF:
- return check_buffer_access(env, reg, regno, reg->off,
- access_size, zero_size_allowed,
- "rdwr",
- &env->prog->aux->max_rdwr_access);
- case PTR_TO_STACK:
- return check_stack_range_initialized(
- env,
- regno, reg->off, access_size,
- zero_size_allowed, ACCESS_HELPER, meta);
- default: /* scalar_value or invalid ptr */
- /* Allow zero-byte read from NULL, regardless of pointer type */
- if (zero_size_allowed && access_size == 0 &&
- register_is_null(reg))
- return 0;
- verbose(env, "R%d type=%s expected=%s\n", regno,
- reg_type_str[reg->type],
- reg_type_str[PTR_TO_STACK]);
- return -EACCES;
- }
- }
- /* Implementation details:
- * bpf_map_lookup returns PTR_TO_MAP_VALUE_OR_NULL
- * Two bpf_map_lookups (even with the same key) will have different reg->id.
- * For traditional PTR_TO_MAP_VALUE the verifier clears reg->id after
- * value_or_null->value transition, since the verifier only cares about
- * the range of access to valid map value pointer and doesn't care about actual
- * address of the map element.
- * For maps with 'struct bpf_spin_lock' inside map value the verifier keeps
- * reg->id > 0 after value_or_null->value transition. By doing so
- * two bpf_map_lookups will be considered two different pointers that
- * point to different bpf_spin_locks.
- * The verifier allows taking only one bpf_spin_lock at a time to avoid
- * dead-locks.
- * Since only one bpf_spin_lock is allowed the checks are simpler than
- * reg_is_refcounted() logic. The verifier needs to remember only
- * one spin_lock instead of array of acquired_refs.
- * cur_state->active_spin_lock remembers which map value element got locked
- * and clears it after bpf_spin_unlock.
- */
- static int process_spin_lock(struct bpf_verifier_env *env, int regno,
- bool is_lock)
- {
- struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
- struct bpf_verifier_state *cur = env->cur_state;
- bool is_const = tnum_is_const(reg->var_off);
- struct bpf_map *map = reg->map_ptr;
- u64 val = reg->var_off.value;
- if (!is_const) {
- verbose(env,
- "R%d doesn't have constant offset. bpf_spin_lock has to be at the constant offset\n",
- regno);
- return -EINVAL;
- }
- if (!map->btf) {
- verbose(env,
- "map '%s' has to have BTF in order to use bpf_spin_lock\n",
- map->name);
- return -EINVAL;
- }
- if (!map_value_has_spin_lock(map)) {
- if (map->spin_lock_off == -E2BIG)
- verbose(env,
- "map '%s' has more than one 'struct bpf_spin_lock'\n",
- map->name);
- else if (map->spin_lock_off == -ENOENT)
- verbose(env,
- "map '%s' doesn't have 'struct bpf_spin_lock'\n",
- map->name);
- else
- verbose(env,
- "map '%s' is not a struct type or bpf_spin_lock is mangled\n",
- map->name);
- return -EINVAL;
- }
- if (map->spin_lock_off != val + reg->off) {
- verbose(env, "off %lld doesn't point to 'struct bpf_spin_lock'\n",
- val + reg->off);
- return -EINVAL;
- }
- if (is_lock) {
- if (cur->active_spin_lock) {
- verbose(env,
- "Locking two bpf_spin_locks are not allowed\n");
- return -EINVAL;
- }
- cur->active_spin_lock = reg->id;
- } else {
- if (!cur->active_spin_lock) {
- verbose(env, "bpf_spin_unlock without taking a lock\n");
- return -EINVAL;
- }
- if (cur->active_spin_lock != reg->id) {
- verbose(env, "bpf_spin_unlock of different lock\n");
- return -EINVAL;
- }
- cur->active_spin_lock = 0;
- }
- return 0;
- }
- static bool arg_type_is_mem_ptr(enum bpf_arg_type type)
- {
- return type == ARG_PTR_TO_MEM ||
- type == ARG_PTR_TO_MEM_OR_NULL ||
- type == ARG_PTR_TO_UNINIT_MEM;
- }
- static bool arg_type_is_mem_size(enum bpf_arg_type type)
- {
- return type == ARG_CONST_SIZE ||
- type == ARG_CONST_SIZE_OR_ZERO;
- }
- static bool arg_type_is_alloc_size(enum bpf_arg_type type)
- {
- return type == ARG_CONST_ALLOC_SIZE_OR_ZERO;
- }
- static bool arg_type_is_int_ptr(enum bpf_arg_type type)
- {
- return type == ARG_PTR_TO_INT ||
- type == ARG_PTR_TO_LONG;
- }
- static int int_ptr_type_to_size(enum bpf_arg_type type)
- {
- if (type == ARG_PTR_TO_INT)
- return sizeof(u32);
- else if (type == ARG_PTR_TO_LONG)
- return sizeof(u64);
- return -EINVAL;
- }
- static int resolve_map_arg_type(struct bpf_verifier_env *env,
- const struct bpf_call_arg_meta *meta,
- enum bpf_arg_type *arg_type)
- {
- if (!meta->map_ptr) {
- /* kernel subsystem misconfigured verifier */
- verbose(env, "invalid map_ptr to access map->type\n");
- return -EACCES;
- }
- switch (meta->map_ptr->map_type) {
- case BPF_MAP_TYPE_SOCKMAP:
- case BPF_MAP_TYPE_SOCKHASH:
- if (*arg_type == ARG_PTR_TO_MAP_VALUE) {
- *arg_type = ARG_PTR_TO_BTF_ID_SOCK_COMMON;
- } else {
- verbose(env, "invalid arg_type for sockmap/sockhash\n");
- return -EINVAL;
- }
- break;
- default:
- break;
- }
- return 0;
- }
- struct bpf_reg_types {
- const enum bpf_reg_type types[10];
- u32 *btf_id;
- };
- static const struct bpf_reg_types map_key_value_types = {
- .types = {
- PTR_TO_STACK,
- PTR_TO_PACKET,
- PTR_TO_PACKET_META,
- PTR_TO_MAP_VALUE,
- },
- };
- static const struct bpf_reg_types sock_types = {
- .types = {
- PTR_TO_SOCK_COMMON,
- PTR_TO_SOCKET,
- PTR_TO_TCP_SOCK,
- PTR_TO_XDP_SOCK,
- },
- };
- #ifdef CONFIG_NET
- static const struct bpf_reg_types btf_id_sock_common_types = {
- .types = {
- PTR_TO_SOCK_COMMON,
- PTR_TO_SOCKET,
- PTR_TO_TCP_SOCK,
- PTR_TO_XDP_SOCK,
- PTR_TO_BTF_ID,
- },
- .btf_id = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
- };
- #endif
- static const struct bpf_reg_types mem_types = {
- .types = {
- PTR_TO_STACK,
- PTR_TO_PACKET,
- PTR_TO_PACKET_META,
- PTR_TO_MAP_VALUE,
- PTR_TO_MEM,
- PTR_TO_RDONLY_BUF,
- PTR_TO_RDWR_BUF,
- },
- };
- static const struct bpf_reg_types int_ptr_types = {
- .types = {
- PTR_TO_STACK,
- PTR_TO_PACKET,
- PTR_TO_PACKET_META,
- PTR_TO_MAP_VALUE,
- },
- };
- static const struct bpf_reg_types fullsock_types = { .types = { PTR_TO_SOCKET } };
- static const struct bpf_reg_types scalar_types = { .types = { SCALAR_VALUE } };
- static const struct bpf_reg_types context_types = { .types = { PTR_TO_CTX } };
- static const struct bpf_reg_types alloc_mem_types = { .types = { PTR_TO_MEM } };
- static const struct bpf_reg_types const_map_ptr_types = { .types = { CONST_PTR_TO_MAP } };
- static const struct bpf_reg_types btf_ptr_types = { .types = { PTR_TO_BTF_ID } };
- static const struct bpf_reg_types spin_lock_types = { .types = { PTR_TO_MAP_VALUE } };
- static const struct bpf_reg_types percpu_btf_ptr_types = { .types = { PTR_TO_PERCPU_BTF_ID } };
- static const struct bpf_reg_types *compatible_reg_types[__BPF_ARG_TYPE_MAX] = {
- [ARG_PTR_TO_MAP_KEY] = &map_key_value_types,
- [ARG_PTR_TO_MAP_VALUE] = &map_key_value_types,
- [ARG_PTR_TO_UNINIT_MAP_VALUE] = &map_key_value_types,
- [ARG_PTR_TO_MAP_VALUE_OR_NULL] = &map_key_value_types,
- [ARG_CONST_SIZE] = &scalar_types,
- [ARG_CONST_SIZE_OR_ZERO] = &scalar_types,
- [ARG_CONST_ALLOC_SIZE_OR_ZERO] = &scalar_types,
- [ARG_CONST_MAP_PTR] = &const_map_ptr_types,
- [ARG_PTR_TO_CTX] = &context_types,
- [ARG_PTR_TO_CTX_OR_NULL] = &context_types,
- [ARG_PTR_TO_SOCK_COMMON] = &sock_types,
- #ifdef CONFIG_NET
- [ARG_PTR_TO_BTF_ID_SOCK_COMMON] = &btf_id_sock_common_types,
- #endif
- [ARG_PTR_TO_SOCKET] = &fullsock_types,
- [ARG_PTR_TO_SOCKET_OR_NULL] = &fullsock_types,
- [ARG_PTR_TO_BTF_ID] = &btf_ptr_types,
- [ARG_PTR_TO_SPIN_LOCK] = &spin_lock_types,
- [ARG_PTR_TO_MEM] = &mem_types,
- [ARG_PTR_TO_MEM_OR_NULL] = &mem_types,
- [ARG_PTR_TO_UNINIT_MEM] = &mem_types,
- [ARG_PTR_TO_ALLOC_MEM] = &alloc_mem_types,
- [ARG_PTR_TO_ALLOC_MEM_OR_NULL] = &alloc_mem_types,
- [ARG_PTR_TO_INT] = &int_ptr_types,
- [ARG_PTR_TO_LONG] = &int_ptr_types,
- [ARG_PTR_TO_PERCPU_BTF_ID] = &percpu_btf_ptr_types,
- };
- static int check_reg_type(struct bpf_verifier_env *env, u32 regno,
- enum bpf_arg_type arg_type,
- const u32 *arg_btf_id)
- {
- struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
- enum bpf_reg_type expected, type = reg->type;
- const struct bpf_reg_types *compatible;
- int i, j;
- compatible = compatible_reg_types[arg_type];
- if (!compatible) {
- verbose(env, "verifier internal error: unsupported arg type %d\n", arg_type);
- return -EFAULT;
- }
- for (i = 0; i < ARRAY_SIZE(compatible->types); i++) {
- expected = compatible->types[i];
- if (expected == NOT_INIT)
- break;
- if (type == expected)
- goto found;
- }
- verbose(env, "R%d type=%s expected=", regno, reg_type_str[type]);
- for (j = 0; j + 1 < i; j++)
- verbose(env, "%s, ", reg_type_str[compatible->types[j]]);
- verbose(env, "%s\n", reg_type_str[compatible->types[j]]);
- return -EACCES;
- found:
- if (type == PTR_TO_BTF_ID) {
- if (!arg_btf_id) {
- if (!compatible->btf_id) {
- verbose(env, "verifier internal error: missing arg compatible BTF ID\n");
- return -EFAULT;
- }
- arg_btf_id = compatible->btf_id;
- }
- if (!btf_struct_ids_match(&env->log, reg->off, reg->btf_id,
- *arg_btf_id)) {
- verbose(env, "R%d is of type %s but %s is expected\n",
- regno, kernel_type_name(reg->btf_id),
- kernel_type_name(*arg_btf_id));
- return -EACCES;
- }
- if (!tnum_is_const(reg->var_off) || reg->var_off.value) {
- verbose(env, "R%d is a pointer to in-kernel struct with non-zero offset\n",
- regno);
- return -EACCES;
- }
- }
- return 0;
- }
- static int check_func_arg(struct bpf_verifier_env *env, u32 arg,
- struct bpf_call_arg_meta *meta,
- const struct bpf_func_proto *fn)
- {
- u32 regno = BPF_REG_1 + arg;
- struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno];
- enum bpf_arg_type arg_type = fn->arg_type[arg];
- enum bpf_reg_type type = reg->type;
- int err = 0;
- if (arg_type == ARG_DONTCARE)
- return 0;
- err = check_reg_arg(env, regno, SRC_OP);
- if (err)
- return err;
- if (arg_type == ARG_ANYTHING) {
- if (is_pointer_value(env, regno)) {
- verbose(env, "R%d leaks addr into helper function\n",
- regno);
- return -EACCES;
- }
- return 0;
- }
- if (type_is_pkt_pointer(type) &&
- !may_access_direct_pkt_data(env, meta, BPF_READ)) {
- verbose(env, "helper access to the packet is not allowed\n");
- return -EACCES;
- }
- if (arg_type == ARG_PTR_TO_MAP_VALUE ||
- arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE ||
- arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL) {
- err = resolve_map_arg_type(env, meta, &arg_type);
- if (err)
- return err;
- }
- if (register_is_null(reg) && arg_type_may_be_null(arg_type))
- /* A NULL register has a SCALAR_VALUE type, so skip
- * type checking.
- */
- goto skip_type_check;
- err = check_reg_type(env, regno, arg_type, fn->arg_btf_id[arg]);
- if (err)
- return err;
- if (type == PTR_TO_CTX) {
- err = check_ctx_reg(env, reg, regno);
- if (err < 0)
- return err;
- }
- skip_type_check:
- if (reg->ref_obj_id) {
- if (meta->ref_obj_id) {
- verbose(env, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n",
- regno, reg->ref_obj_id,
- meta->ref_obj_id);
- return -EFAULT;
- }
- meta->ref_obj_id = reg->ref_obj_id;
- }
- if (arg_type == ARG_CONST_MAP_PTR) {
- /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
- meta->map_ptr = reg->map_ptr;
- } else if (arg_type == ARG_PTR_TO_MAP_KEY) {
- /* bpf_map_xxx(..., map_ptr, ..., key) call:
- * check that [key, key + map->key_size) are within
- * stack limits and initialized
- */
- if (!meta->map_ptr) {
- /* in function declaration map_ptr must come before
- * map_key, so that it's verified and known before
- * we have to check map_key here. Otherwise it means
- * that kernel subsystem misconfigured verifier
- */
- verbose(env, "invalid map_ptr to access map->key\n");
- return -EACCES;
- }
- err = check_helper_mem_access(env, regno,
- meta->map_ptr->key_size, false,
- NULL);
- } else if (arg_type == ARG_PTR_TO_MAP_VALUE ||
- (arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL &&
- !register_is_null(reg)) ||
- arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE) {
- /* bpf_map_xxx(..., map_ptr, ..., value) call:
- * check [value, value + map->value_size) validity
- */
- if (!meta->map_ptr) {
- /* kernel subsystem misconfigured verifier */
- verbose(env, "invalid map_ptr to access map->value\n");
- return -EACCES;
- }
- meta->raw_mode = (arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE);
- err = check_helper_mem_access(env, regno,
- meta->map_ptr->value_size, false,
- meta);
- } else if (arg_type == ARG_PTR_TO_PERCPU_BTF_ID) {
- if (!reg->btf_id) {
- verbose(env, "Helper has invalid btf_id in R%d\n", regno);
- return -EACCES;
- }
- meta->ret_btf_id = reg->btf_id;
- } else if (arg_type == ARG_PTR_TO_SPIN_LOCK) {
- if (meta->func_id == BPF_FUNC_spin_lock) {
- if (process_spin_lock(env, regno, true))
- return -EACCES;
- } else if (meta->func_id == BPF_FUNC_spin_unlock) {
- if (process_spin_lock(env, regno, false))
- return -EACCES;
- } else {
- verbose(env, "verifier internal error\n");
- return -EFAULT;
- }
- } else if (arg_type_is_mem_ptr(arg_type)) {
- /* The access to this pointer is only checked when we hit the
- * next is_mem_size argument below.
- */
- meta->raw_mode = (arg_type == ARG_PTR_TO_UNINIT_MEM);
- } else if (arg_type_is_mem_size(arg_type)) {
- bool zero_size_allowed = (arg_type == ARG_CONST_SIZE_OR_ZERO);
- /* This is used to refine r0 return value bounds for helpers
- * that enforce this value as an upper bound on return values.
- * See do_refine_retval_range() for helpers that can refine
- * the return value. C type of helper is u32 so we pull register
- * bound from umax_value however, if negative verifier errors
- * out. Only upper bounds can be learned because retval is an
- * int type and negative retvals are allowed.
- */
- meta->msize_max_value = reg->umax_value;
- /* The register is SCALAR_VALUE; the access check
- * happens using its boundaries.
- */
- if (!tnum_is_const(reg->var_off))
- /* For unprivileged variable accesses, disable raw
- * mode so that the program is required to
- * initialize all the memory that the helper could
- * just partially fill up.
- */
- meta = NULL;
- if (reg->smin_value < 0) {
- verbose(env, "R%d min value is negative, either use unsigned or 'var &= const'\n",
- regno);
- return -EACCES;
- }
- if (reg->umin_value == 0) {
- err = check_helper_mem_access(env, regno - 1, 0,
- zero_size_allowed,
- meta);
- if (err)
- return err;
- }
- if (reg->umax_value >= BPF_MAX_VAR_SIZ) {
- verbose(env, "R%d unbounded memory access, use 'var &= const' or 'if (var < const)'\n",
- regno);
- return -EACCES;
- }
- err = check_helper_mem_access(env, regno - 1,
- reg->umax_value,
- zero_size_allowed, meta);
- if (!err)
- err = mark_chain_precision(env, regno);
- } else if (arg_type_is_alloc_size(arg_type)) {
- if (!tnum_is_const(reg->var_off)) {
- verbose(env, "R%d unbounded size, use 'var &= const' or 'if (var < const)'\n",
- regno);
- return -EACCES;
- }
- meta->mem_size = reg->var_off.value;
- } else if (arg_type_is_int_ptr(arg_type)) {
- int size = int_ptr_type_to_size(arg_type);
- err = check_helper_mem_access(env, regno, size, false, meta);
- if (err)
- return err;
- err = check_ptr_alignment(env, reg, 0, size, true);
- }
- return err;
- }
- static bool may_update_sockmap(struct bpf_verifier_env *env, int func_id)
- {
- enum bpf_attach_type eatype = env->prog->expected_attach_type;
- enum bpf_prog_type type = resolve_prog_type(env->prog);
- if (func_id != BPF_FUNC_map_update_elem)
- return false;
- /* It's not possible to get access to a locked struct sock in these
- * contexts, so updating is safe.
- */
- switch (type) {
- case BPF_PROG_TYPE_TRACING:
- if (eatype == BPF_TRACE_ITER)
- return true;
- break;
- case BPF_PROG_TYPE_SOCKET_FILTER:
- case BPF_PROG_TYPE_SCHED_CLS:
- case BPF_PROG_TYPE_SCHED_ACT:
- case BPF_PROG_TYPE_XDP:
- case BPF_PROG_TYPE_SK_REUSEPORT:
- case BPF_PROG_TYPE_FLOW_DISSECTOR:
- case BPF_PROG_TYPE_SK_LOOKUP:
- return true;
- default:
- break;
- }
- verbose(env, "cannot update sockmap in this context\n");
- return false;
- }
- static bool allow_tail_call_in_subprogs(struct bpf_verifier_env *env)
- {
- return env->prog->jit_requested && IS_ENABLED(CONFIG_X86_64);
- }
- static int check_map_func_compatibility(struct bpf_verifier_env *env,
- struct bpf_map *map, int func_id)
- {
- if (!map)
- return 0;
- /* We need a two way check, first is from map perspective ... */
- switch (map->map_type) {
- case BPF_MAP_TYPE_PROG_ARRAY:
- if (func_id != BPF_FUNC_tail_call)
- goto error;
- break;
- case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
- if (func_id != BPF_FUNC_perf_event_read &&
- func_id != BPF_FUNC_perf_event_output &&
- func_id != BPF_FUNC_skb_output &&
- func_id != BPF_FUNC_perf_event_read_value &&
- func_id != BPF_FUNC_xdp_output)
- goto error;
- break;
- case BPF_MAP_TYPE_RINGBUF:
- if (func_id != BPF_FUNC_ringbuf_output &&
- func_id != BPF_FUNC_ringbuf_reserve &&
- func_id != BPF_FUNC_ringbuf_query)
- goto error;
- break;
- case BPF_MAP_TYPE_STACK_TRACE:
- if (func_id != BPF_FUNC_get_stackid)
- goto error;
- break;
- case BPF_MAP_TYPE_CGROUP_ARRAY:
- if (func_id != BPF_FUNC_skb_under_cgroup &&
- func_id != BPF_FUNC_current_task_under_cgroup)
- goto error;
- break;
- case BPF_MAP_TYPE_CGROUP_STORAGE:
- case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
- if (func_id != BPF_FUNC_get_local_storage)
- goto error;
- break;
- case BPF_MAP_TYPE_DEVMAP:
- case BPF_MAP_TYPE_DEVMAP_HASH:
- if (func_id != BPF_FUNC_redirect_map &&
- func_id != BPF_FUNC_map_lookup_elem)
- goto error;
- break;
- /* Restrict bpf side of cpumap and xskmap, open when use-cases
- * appear.
- */
- case BPF_MAP_TYPE_CPUMAP:
- if (func_id != BPF_FUNC_redirect_map)
- goto error;
- break;
- case BPF_MAP_TYPE_XSKMAP:
- if (func_id != BPF_FUNC_redirect_map &&
- func_id != BPF_FUNC_map_lookup_elem)
- goto error;
- break;
- case BPF_MAP_TYPE_ARRAY_OF_MAPS:
- case BPF_MAP_TYPE_HASH_OF_MAPS:
- if (func_id != BPF_FUNC_map_lookup_elem)
- goto error;
- break;
- case BPF_MAP_TYPE_SOCKMAP:
- if (func_id != BPF_FUNC_sk_redirect_map &&
- func_id != BPF_FUNC_sock_map_update &&
- func_id != BPF_FUNC_map_delete_elem &&
- func_id != BPF_FUNC_msg_redirect_map &&
- func_id != BPF_FUNC_sk_select_reuseport &&
- func_id != BPF_FUNC_map_lookup_elem &&
- !may_update_sockmap(env, func_id))
- goto error;
- break;
- case BPF_MAP_TYPE_SOCKHASH:
- if (func_id != BPF_FUNC_sk_redirect_hash &&
- func_id != BPF_FUNC_sock_hash_update &&
- func_id != BPF_FUNC_map_delete_elem &&
- func_id != BPF_FUNC_msg_redirect_hash &&
- func_id != BPF_FUNC_sk_select_reuseport &&
- func_id != BPF_FUNC_map_lookup_elem &&
- !may_update_sockmap(env, func_id))
- goto error;
- break;
- case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
- if (func_id != BPF_FUNC_sk_select_reuseport)
- goto error;
- break;
- case BPF_MAP_TYPE_QUEUE:
- case BPF_MAP_TYPE_STACK:
- if (func_id != BPF_FUNC_map_peek_elem &&
- func_id != BPF_FUNC_map_pop_elem &&
- func_id != BPF_FUNC_map_push_elem)
- goto error;
- break;
- case BPF_MAP_TYPE_SK_STORAGE:
- if (func_id != BPF_FUNC_sk_storage_get &&
- func_id != BPF_FUNC_sk_storage_delete)
- goto error;
- break;
- case BPF_MAP_TYPE_INODE_STORAGE:
- if (func_id != BPF_FUNC_inode_storage_get &&
- func_id != BPF_FUNC_inode_storage_delete)
- goto error;
- break;
- default:
- break;
- }
- /* ... and second from the function itself. */
- switch (func_id) {
- case BPF_FUNC_tail_call:
- if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
- goto error;
- if (env->subprog_cnt > 1 && !allow_tail_call_in_subprogs(env)) {
- verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
- return -EINVAL;
- }
- break;
- case BPF_FUNC_perf_event_read:
- case BPF_FUNC_perf_event_output:
- case BPF_FUNC_perf_event_read_value:
- case BPF_FUNC_skb_output:
- case BPF_FUNC_xdp_output:
- if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
- goto error;
- break;
- case BPF_FUNC_ringbuf_output:
- case BPF_FUNC_ringbuf_reserve:
- case BPF_FUNC_ringbuf_query:
- if (map->map_type != BPF_MAP_TYPE_RINGBUF)
- goto error;
- break;
- case BPF_FUNC_get_stackid:
- if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
- goto error;
- break;
- case BPF_FUNC_current_task_under_cgroup:
- case BPF_FUNC_skb_under_cgroup:
- if (map->map_type != BPF_MAP_TYPE_CGROUP_ARRAY)
- goto error;
- break;
- case BPF_FUNC_redirect_map:
- if (map->map_type != BPF_MAP_TYPE_DEVMAP &&
- map->map_type != BPF_MAP_TYPE_DEVMAP_HASH &&
- map->map_type != BPF_MAP_TYPE_CPUMAP &&
- map->map_type != BPF_MAP_TYPE_XSKMAP)
- goto error;
- break;
- case BPF_FUNC_sk_redirect_map:
- case BPF_FUNC_msg_redirect_map:
- case BPF_FUNC_sock_map_update:
- if (map->map_type != BPF_MAP_TYPE_SOCKMAP)
- goto error;
- break;
- case BPF_FUNC_sk_redirect_hash:
- case BPF_FUNC_msg_redirect_hash:
- case BPF_FUNC_sock_hash_update:
- if (map->map_type != BPF_MAP_TYPE_SOCKHASH)
- goto error;
- break;
- case BPF_FUNC_get_local_storage:
- if (map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE &&
- map->map_type != BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE)
- goto error;
- break;
- case BPF_FUNC_sk_select_reuseport:
- if (map->map_type != BPF_MAP_TYPE_REUSEPORT_SOCKARRAY &&
- map->map_type != BPF_MAP_TYPE_SOCKMAP &&
- map->map_type != BPF_MAP_TYPE_SOCKHASH)
- goto error;
- break;
- case BPF_FUNC_map_peek_elem:
- case BPF_FUNC_map_pop_elem:
- case BPF_FUNC_map_push_elem:
- if (map->map_type != BPF_MAP_TYPE_QUEUE &&
- map->map_type != BPF_MAP_TYPE_STACK)
- goto error;
- break;
- case BPF_FUNC_sk_storage_get:
- case BPF_FUNC_sk_storage_delete:
- if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
- goto error;
- break;
- case BPF_FUNC_inode_storage_get:
- case BPF_FUNC_inode_storage_delete:
- if (map->map_type != BPF_MAP_TYPE_INODE_STORAGE)
- goto error;
- break;
- default:
- break;
- }
- return 0;
- error:
- verbose(env, "cannot pass map_type %d into func %s#%d\n",
- map->map_type, func_id_name(func_id), func_id);
- return -EINVAL;
- }
- static bool check_raw_mode_ok(const struct bpf_func_proto *fn)
- {
- int count = 0;
- if (fn->arg1_type == ARG_PTR_TO_UNINIT_MEM)
- count++;
- if (fn->arg2_type == ARG_PTR_TO_UNINIT_MEM)
- count++;
- if (fn->arg3_type == ARG_PTR_TO_UNINIT_MEM)
- count++;
- if (fn->arg4_type == ARG_PTR_TO_UNINIT_MEM)
- count++;
- if (fn->arg5_type == ARG_PTR_TO_UNINIT_MEM)
- count++;
- /* We only support one arg being in raw mode at the moment,
- * which is sufficient for the helper functions we have
- * right now.
- */
- return count <= 1;
- }
- static bool check_args_pair_invalid(enum bpf_arg_type arg_curr,
- enum bpf_arg_type arg_next)
- {
- return (arg_type_is_mem_ptr(arg_curr) &&
- !arg_type_is_mem_size(arg_next)) ||
- (!arg_type_is_mem_ptr(arg_curr) &&
- arg_type_is_mem_size(arg_next));
- }
- static bool check_arg_pair_ok(const struct bpf_func_proto *fn)
- {
- /* bpf_xxx(..., buf, len) call will access 'len'
- * bytes from memory 'buf'. Both arg types need
- * to be paired, so make sure there's no buggy
- * helper function specification.
- */
- if (arg_type_is_mem_size(fn->arg1_type) ||
- arg_type_is_mem_ptr(fn->arg5_type) ||
- check_args_pair_invalid(fn->arg1_type, fn->arg2_type) ||
- check_args_pair_invalid(fn->arg2_type, fn->arg3_type) ||
- check_args_pair_invalid(fn->arg3_type, fn->arg4_type) ||
- check_args_pair_invalid(fn->arg4_type, fn->arg5_type))
- return false;
- return true;
- }
- static bool check_refcount_ok(const struct bpf_func_proto *fn, int func_id)
- {
- int count = 0;
- if (arg_type_may_be_refcounted(fn->arg1_type))
- count++;
- if (arg_type_may_be_refcounted(fn->arg2_type))
- count++;
- if (arg_type_may_be_refcounted(fn->arg3_type))
- count++;
- if (arg_type_may_be_refcounted(fn->arg4_type))
- count++;
- if (arg_type_may_be_refcounted(fn->arg5_type))
- count++;
- /* A reference acquiring function cannot acquire
- * another refcounted ptr.
- */
- if (may_be_acquire_function(func_id) && count)
- return false;
- /* We only support one arg being unreferenced at the moment,
- * which is sufficient for the helper functions we have right now.
- */
- return count <= 1;
- }
- static bool check_btf_id_ok(const struct bpf_func_proto *fn)
- {
- int i;
- for (i = 0; i < ARRAY_SIZE(fn->arg_type); i++) {
- if (fn->arg_type[i] == ARG_PTR_TO_BTF_ID && !fn->arg_btf_id[i])
- return false;
- if (fn->arg_type[i] != ARG_PTR_TO_BTF_ID && fn->arg_btf_id[i])
- return false;
- }
- return true;
- }
- static int check_func_proto(const struct bpf_func_proto *fn, int func_id)
- {
- return check_raw_mode_ok(fn) &&
- check_arg_pair_ok(fn) &&
- check_btf_id_ok(fn) &&
- check_refcount_ok(fn, func_id) ? 0 : -EINVAL;
- }
- /* Packet data might have moved, any old PTR_TO_PACKET[_META,_END]
- * are now invalid, so turn them into unknown SCALAR_VALUE.
- */
- static void __clear_all_pkt_pointers(struct bpf_verifier_env *env,
- struct bpf_func_state *state)
- {
- struct bpf_reg_state *regs = state->regs, *reg;
- int i;
- for (i = 0; i < MAX_BPF_REG; i++)
- if (reg_is_pkt_pointer_any(®s[i]))
- mark_reg_unknown(env, regs, i);
- bpf_for_each_spilled_reg(i, state, reg) {
- if (!reg)
- continue;
- if (reg_is_pkt_pointer_any(reg))
- __mark_reg_unknown(env, reg);
- }
- }
- static void clear_all_pkt_pointers(struct bpf_verifier_env *env)
- {
- struct bpf_verifier_state *vstate = env->cur_state;
- int i;
- for (i = 0; i <= vstate->curframe; i++)
- __clear_all_pkt_pointers(env, vstate->frame[i]);
- }
- static void release_reg_references(struct bpf_verifier_env *env,
- struct bpf_func_state *state,
- int ref_obj_id)
- {
- struct bpf_reg_state *regs = state->regs, *reg;
- int i;
- for (i = 0; i < MAX_BPF_REG; i++)
- if (regs[i].ref_obj_id == ref_obj_id)
- mark_reg_unknown(env, regs, i);
- bpf_for_each_spilled_reg(i, state, reg) {
- if (!reg)
- continue;
- if (reg->ref_obj_id == ref_obj_id)
- __mark_reg_unknown(env, reg);
- }
- }
- /* The pointer with the specified id has released its reference to kernel
- * resources. Identify all copies of the same pointer and clear the reference.
- */
- static int release_reference(struct bpf_verifier_env *env,
- int ref_obj_id)
- {
- struct bpf_verifier_state *vstate = env->cur_state;
- int err;
- int i;
- err = release_reference_state(cur_func(env), ref_obj_id);
- if (err)
- return err;
- for (i = 0; i <= vstate->curframe; i++)
- release_reg_references(env, vstate->frame[i], ref_obj_id);
- return 0;
- }
- static void clear_caller_saved_regs(struct bpf_verifier_env *env,
- struct bpf_reg_state *regs)
- {
- int i;
- /* after the call registers r0 - r5 were scratched */
- for (i = 0; i < CALLER_SAVED_REGS; i++) {
- mark_reg_not_init(env, regs, caller_saved[i]);
- check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
- }
- }
- static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
- int *insn_idx)
- {
- struct bpf_verifier_state *state = env->cur_state;
- struct bpf_func_info_aux *func_info_aux;
- struct bpf_func_state *caller, *callee;
- int i, err, subprog, target_insn;
- bool is_global = false;
- if (state->curframe + 1 >= MAX_CALL_FRAMES) {
- verbose(env, "the call stack of %d frames is too deep\n",
- state->curframe + 2);
- return -E2BIG;
- }
- target_insn = *insn_idx + insn->imm;
- subprog = find_subprog(env, target_insn + 1);
- if (subprog < 0) {
- verbose(env, "verifier bug. No program starts at insn %d\n",
- target_insn + 1);
- return -EFAULT;
- }
- caller = state->frame[state->curframe];
- if (state->frame[state->curframe + 1]) {
- verbose(env, "verifier bug. Frame %d already allocated\n",
- state->curframe + 1);
- return -EFAULT;
- }
- func_info_aux = env->prog->aux->func_info_aux;
- if (func_info_aux)
- is_global = func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL;
- err = btf_check_func_arg_match(env, subprog, caller->regs);
- if (err == -EFAULT)
- return err;
- if (is_global) {
- if (err) {
- verbose(env, "Caller passes invalid args into func#%d\n",
- subprog);
- return err;
- } else {
- if (env->log.level & BPF_LOG_LEVEL)
- verbose(env,
- "Func#%d is global and valid. Skipping.\n",
- subprog);
- clear_caller_saved_regs(env, caller->regs);
- /* All global functions return a 64-bit SCALAR_VALUE */
- mark_reg_unknown(env, caller->regs, BPF_REG_0);
- caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;
- /* continue with next insn after call */
- return 0;
- }
- }
- callee = kzalloc(sizeof(*callee), GFP_KERNEL);
- if (!callee)
- return -ENOMEM;
- state->frame[state->curframe + 1] = callee;
- /* callee cannot access r0, r6 - r9 for reading and has to write
- * into its own stack before reading from it.
- * callee can read/write into caller's stack
- */
- init_func_state(env, callee,
- /* remember the callsite, it will be used by bpf_exit */
- *insn_idx /* callsite */,
- state->curframe + 1 /* frameno within this callchain */,
- subprog /* subprog number within this prog */);
- /* Transfer references to the callee */
- err = transfer_reference_state(callee, caller);
- if (err)
- return err;
- /* copy r1 - r5 args that callee can access. The copy includes parent
- * pointers, which connects us up to the liveness chain
- */
- for (i = BPF_REG_1; i <= BPF_REG_5; i++)
- callee->regs[i] = caller->regs[i];
- clear_caller_saved_regs(env, caller->regs);
- /* only increment it after check_reg_arg() finished */
- state->curframe++;
- /* and go analyze first insn of the callee */
- *insn_idx = target_insn;
- if (env->log.level & BPF_LOG_LEVEL) {
- verbose(env, "caller:\n");
- print_verifier_state(env, caller);
- verbose(env, "callee:\n");
- print_verifier_state(env, callee);
- }
- return 0;
- }
- static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx)
- {
- struct bpf_verifier_state *state = env->cur_state;
- struct bpf_func_state *caller, *callee;
- struct bpf_reg_state *r0;
- int err;
- callee = state->frame[state->curframe];
- r0 = &callee->regs[BPF_REG_0];
- if (r0->type == PTR_TO_STACK) {
- /* technically it's ok to return caller's stack pointer
- * (or caller's caller's pointer) back to the caller,
- * since these pointers are valid. Only current stack
- * pointer will be invalid as soon as function exits,
- * but let's be conservative
- */
- verbose(env, "cannot return stack pointer to the caller\n");
- return -EINVAL;
- }
- state->curframe--;
- caller = state->frame[state->curframe];
- /* return to the caller whatever r0 had in the callee */
- caller->regs[BPF_REG_0] = *r0;
- /* Transfer references to the caller */
- err = transfer_reference_state(caller, callee);
- if (err)
- return err;
- *insn_idx = callee->callsite + 1;
- if (env->log.level & BPF_LOG_LEVEL) {
- verbose(env, "returning from callee:\n");
- print_verifier_state(env, callee);
- verbose(env, "to caller at %d:\n", *insn_idx);
- print_verifier_state(env, caller);
- }
- /* clear everything in the callee */
- free_func_state(callee);
- state->frame[state->curframe + 1] = NULL;
- return 0;
- }
- static void do_refine_retval_range(struct bpf_reg_state *regs, int ret_type,
- int func_id,
- struct bpf_call_arg_meta *meta)
- {
- struct bpf_reg_state *ret_reg = ®s[BPF_REG_0];
- if (ret_type != RET_INTEGER ||
- (func_id != BPF_FUNC_get_stack &&
- func_id != BPF_FUNC_probe_read_str &&
- func_id != BPF_FUNC_probe_read_kernel_str &&
- func_id != BPF_FUNC_probe_read_user_str))
- return;
- ret_reg->smax_value = meta->msize_max_value;
- ret_reg->s32_max_value = meta->msize_max_value;
- ret_reg->smin_value = -MAX_ERRNO;
- ret_reg->s32_min_value = -MAX_ERRNO;
- __reg_deduce_bounds(ret_reg);
- __reg_bound_offset(ret_reg);
- __update_reg_bounds(ret_reg);
- }
- static int
- record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
- int func_id, int insn_idx)
- {
- struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
- struct bpf_map *map = meta->map_ptr;
- if (func_id != BPF_FUNC_tail_call &&
- func_id != BPF_FUNC_map_lookup_elem &&
- func_id != BPF_FUNC_map_update_elem &&
- func_id != BPF_FUNC_map_delete_elem &&
- func_id != BPF_FUNC_map_push_elem &&
- func_id != BPF_FUNC_map_pop_elem &&
- func_id != BPF_FUNC_map_peek_elem)
- return 0;
- if (map == NULL) {
- verbose(env, "kernel subsystem misconfigured verifier\n");
- return -EINVAL;
- }
- /* In case of read-only, some additional restrictions
- * need to be applied in order to prevent altering the
- * state of the map from program side.
- */
- if ((map->map_flags & BPF_F_RDONLY_PROG) &&
- (func_id == BPF_FUNC_map_delete_elem ||
- func_id == BPF_FUNC_map_update_elem ||
- func_id == BPF_FUNC_map_push_elem ||
- func_id == BPF_FUNC_map_pop_elem)) {
- verbose(env, "write into map forbidden\n");
- return -EACCES;
- }
- if (!BPF_MAP_PTR(aux->map_ptr_state))
- bpf_map_ptr_store(aux, meta->map_ptr,
- !meta->map_ptr->bypass_spec_v1);
- else if (BPF_MAP_PTR(aux->map_ptr_state) != meta->map_ptr)
- bpf_map_ptr_store(aux, BPF_MAP_PTR_POISON,
- !meta->map_ptr->bypass_spec_v1);
- return 0;
- }
- static int
- record_func_key(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
- int func_id, int insn_idx)
- {
- struct bpf_insn_aux_data *aux = &env->insn_aux_data[insn_idx];
- struct bpf_reg_state *regs = cur_regs(env), *reg;
- struct bpf_map *map = meta->map_ptr;
- struct tnum range;
- u64 val;
- int err;
- if (func_id != BPF_FUNC_tail_call)
- return 0;
- if (!map || map->map_type != BPF_MAP_TYPE_PROG_ARRAY) {
- verbose(env, "kernel subsystem misconfigured verifier\n");
- return -EINVAL;
- }
- range = tnum_range(0, map->max_entries - 1);
- reg = ®s[BPF_REG_3];
- if (!register_is_const(reg) || !tnum_in(range, reg->var_off)) {
- bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
- return 0;
- }
- err = mark_chain_precision(env, BPF_REG_3);
- if (err)
- return err;
- val = reg->var_off.value;
- if (bpf_map_key_unseen(aux))
- bpf_map_key_store(aux, val);
- else if (!bpf_map_key_poisoned(aux) &&
- bpf_map_key_immediate(aux) != val)
- bpf_map_key_store(aux, BPF_MAP_KEY_POISON);
- return 0;
- }
- static int check_reference_leak(struct bpf_verifier_env *env)
- {
- struct bpf_func_state *state = cur_func(env);
- int i;
- for (i = 0; i < state->acquired_refs; i++) {
- verbose(env, "Unreleased reference id=%d alloc_insn=%d\n",
- state->refs[i].id, state->refs[i].insn_idx);
- }
- return state->acquired_refs ? -EINVAL : 0;
- }
- static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn_idx)
- {
- const struct bpf_func_proto *fn = NULL;
- struct bpf_reg_state *regs;
- struct bpf_call_arg_meta meta;
- bool changes_data;
- int i, err;
- /* find function prototype */
- if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
- verbose(env, "invalid func %s#%d\n", func_id_name(func_id),
- func_id);
- return -EINVAL;
- }
- if (env->ops->get_func_proto)
- fn = env->ops->get_func_proto(func_id, env->prog);
- if (!fn) {
- verbose(env, "unknown func %s#%d\n", func_id_name(func_id),
- func_id);
- return -EINVAL;
- }
- /* eBPF programs must be GPL compatible to use GPL-ed functions */
- if (!env->prog->gpl_compatible && fn->gpl_only) {
- verbose(env, "cannot call GPL-restricted function from non-GPL compatible program\n");
- return -EINVAL;
- }
- if (fn->allowed && !fn->allowed(env->prog)) {
- verbose(env, "helper call is not allowed in probe\n");
- return -EINVAL;
- }
- /* With LD_ABS/IND some JITs save/restore skb from r1. */
- changes_data = bpf_helper_changes_pkt_data(fn->func);
- if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) {
- verbose(env, "kernel subsystem misconfigured func %s#%d: r1 != ctx\n",
- func_id_name(func_id), func_id);
- return -EINVAL;
- }
- memset(&meta, 0, sizeof(meta));
- meta.pkt_access = fn->pkt_access;
- err = check_func_proto(fn, func_id);
- if (err) {
- verbose(env, "kernel subsystem misconfigured func %s#%d\n",
- func_id_name(func_id), func_id);
- return err;
- }
- meta.func_id = func_id;
- /* check args */
- for (i = 0; i < 5; i++) {
- err = check_func_arg(env, i, &meta, fn);
- if (err)
- return err;
- }
- err = record_func_map(env, &meta, func_id, insn_idx);
- if (err)
- return err;
- err = record_func_key(env, &meta, func_id, insn_idx);
- if (err)
- return err;
- /* Mark slots with STACK_MISC in case of raw mode, stack offset
- * is inferred from register state.
- */
- for (i = 0; i < meta.access_size; i++) {
- err = check_mem_access(env, insn_idx, meta.regno, i, BPF_B,
- BPF_WRITE, -1, false);
- if (err)
- return err;
- }
- if (func_id == BPF_FUNC_tail_call) {
- err = check_reference_leak(env);
- if (err) {
- verbose(env, "tail_call would lead to reference leak\n");
- return err;
- }
- } else if (is_release_function(func_id)) {
- err = release_reference(env, meta.ref_obj_id);
- if (err) {
- verbose(env, "func %s#%d reference has not been acquired before\n",
- func_id_name(func_id), func_id);
- return err;
- }
- }
- regs = cur_regs(env);
- /* check that flags argument in get_local_storage(map, flags) is 0,
- * this is required because get_local_storage() can't return an error.
- */
- if (func_id == BPF_FUNC_get_local_storage &&
- !register_is_null(®s[BPF_REG_2])) {
- verbose(env, "get_local_storage() doesn't support non-zero flags\n");
- return -EINVAL;
- }
- /* reset caller saved regs */
- for (i = 0; i < CALLER_SAVED_REGS; i++) {
- mark_reg_not_init(env, regs, caller_saved[i]);
- check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
- }
- /* helper call returns 64-bit value. */
- regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG;
- /* update return register (already marked as written above) */
- if (fn->ret_type == RET_INTEGER) {
- /* sets type to SCALAR_VALUE */
- mark_reg_unknown(env, regs, BPF_REG_0);
- } else if (fn->ret_type == RET_VOID) {
- regs[BPF_REG_0].type = NOT_INIT;
- } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL ||
- fn->ret_type == RET_PTR_TO_MAP_VALUE) {
- /* There is no offset yet applied, variable or fixed */
- mark_reg_known_zero(env, regs, BPF_REG_0);
- /* remember map_ptr, so that check_map_access()
- * can check 'value_size' boundary of memory access
- * to map element returned from bpf_map_lookup_elem()
- */
- if (meta.map_ptr == NULL) {
- verbose(env,
- "kernel subsystem misconfigured verifier\n");
- return -EINVAL;
- }
- regs[BPF_REG_0].map_ptr = meta.map_ptr;
- if (fn->ret_type == RET_PTR_TO_MAP_VALUE) {
- regs[BPF_REG_0].type = PTR_TO_MAP_VALUE;
- if (map_value_has_spin_lock(meta.map_ptr))
- regs[BPF_REG_0].id = ++env->id_gen;
- } else {
- regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
- }
- } else if (fn->ret_type == RET_PTR_TO_SOCKET_OR_NULL) {
- mark_reg_known_zero(env, regs, BPF_REG_0);
- regs[BPF_REG_0].type = PTR_TO_SOCKET_OR_NULL;
- } else if (fn->ret_type == RET_PTR_TO_SOCK_COMMON_OR_NULL) {
- mark_reg_known_zero(env, regs, BPF_REG_0);
- regs[BPF_REG_0].type = PTR_TO_SOCK_COMMON_OR_NULL;
- } else if (fn->ret_type == RET_PTR_TO_TCP_SOCK_OR_NULL) {
- mark_reg_known_zero(env, regs, BPF_REG_0);
- regs[BPF_REG_0].type = PTR_TO_TCP_SOCK_OR_NULL;
- } else if (fn->ret_type == RET_PTR_TO_ALLOC_MEM_OR_NULL) {
- mark_reg_known_zero(env, regs, BPF_REG_0);
- regs[BPF_REG_0].type = PTR_TO_MEM_OR_NULL;
- regs[BPF_REG_0].mem_size = meta.mem_size;
- } else if (fn->ret_type == RET_PTR_TO_MEM_OR_BTF_ID_OR_NULL ||
- fn->ret_type == RET_PTR_TO_MEM_OR_BTF_ID) {
- const struct btf_type *t;
- mark_reg_known_zero(env, regs, BPF_REG_0);
- t = btf_type_skip_modifiers(btf_vmlinux, meta.ret_btf_id, NULL);
- if (!btf_type_is_struct(t)) {
- u32 tsize;
- const struct btf_type *ret;
- const char *tname;
- /* resolve the type size of ksym. */
- ret = btf_resolve_size(btf_vmlinux, t, &tsize);
- if (IS_ERR(ret)) {
- tname = btf_name_by_offset(btf_vmlinux, t->name_off);
- verbose(env, "unable to resolve the size of type '%s': %ld\n",
- tname, PTR_ERR(ret));
- return -EINVAL;
- }
- regs[BPF_REG_0].type =
- fn->ret_type == RET_PTR_TO_MEM_OR_BTF_ID ?
- PTR_TO_MEM : PTR_TO_MEM_OR_NULL;
- regs[BPF_REG_0].mem_size = tsize;
- } else {
- regs[BPF_REG_0].type =
- fn->ret_type == RET_PTR_TO_MEM_OR_BTF_ID ?
- PTR_TO_BTF_ID : PTR_TO_BTF_ID_OR_NULL;
- regs[BPF_REG_0].btf_id = meta.ret_btf_id;
- }
- } else if (fn->ret_type == RET_PTR_TO_BTF_ID_OR_NULL) {
- int ret_btf_id;
- mark_reg_known_zero(env, regs, BPF_REG_0);
- regs[BPF_REG_0].type = PTR_TO_BTF_ID_OR_NULL;
- ret_btf_id = *fn->ret_btf_id;
- if (ret_btf_id == 0) {
- verbose(env, "invalid return type %d of func %s#%d\n",
- fn->ret_type, func_id_name(func_id), func_id);
- return -EINVAL;
- }
- regs[BPF_REG_0].btf_id = ret_btf_id;
- } else {
- verbose(env, "unknown return type %d of func %s#%d\n",
- fn->ret_type, func_id_name(func_id), func_id);
- return -EINVAL;
- }
- if (reg_type_may_be_null(regs[BPF_REG_0].type))
- regs[BPF_REG_0].id = ++env->id_gen;
- if (is_ptr_cast_function(func_id)) {
- /* For release_reference() */
- regs[BPF_REG_0].ref_obj_id = meta.ref_obj_id;
- } else if (is_acquire_function(func_id, meta.map_ptr)) {
- int id = acquire_reference_state(env, insn_idx);
- if (id < 0)
- return id;
- /* For mark_ptr_or_null_reg() */
- regs[BPF_REG_0].id = id;
- /* For release_reference() */
- regs[BPF_REG_0].ref_obj_id = id;
- }
- do_refine_retval_range(regs, fn->ret_type, func_id, &meta);
- err = check_map_func_compatibility(env, meta.map_ptr, func_id);
- if (err)
- return err;
- if ((func_id == BPF_FUNC_get_stack ||
- func_id == BPF_FUNC_get_task_stack) &&
- !env->prog->has_callchain_buf) {
- const char *err_str;
- #ifdef CONFIG_PERF_EVENTS
- err = get_callchain_buffers(sysctl_perf_event_max_stack);
- err_str = "cannot get callchain buffer for func %s#%d\n";
- #else
- err = -ENOTSUPP;
- err_str = "func %s#%d not supported without CONFIG_PERF_EVENTS\n";
- #endif
- if (err) {
- verbose(env, err_str, func_id_name(func_id), func_id);
- return err;
- }
- env->prog->has_callchain_buf = true;
- }
- if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack)
- env->prog->call_get_stack = true;
- if (changes_data)
- clear_all_pkt_pointers(env);
- return 0;
- }
- static bool signed_add_overflows(s64 a, s64 b)
- {
- /* Do the add in u64, where overflow is well-defined */
- s64 res = (s64)((u64)a + (u64)b);
- if (b < 0)
- return res > a;
- return res < a;
- }
- static bool signed_add32_overflows(s32 a, s32 b)
- {
- /* Do the add in u32, where overflow is well-defined */
- s32 res = (s32)((u32)a + (u32)b);
- if (b < 0)
- return res > a;
- return res < a;
- }
- static bool signed_sub_overflows(s64 a, s64 b)
- {
- /* Do the sub in u64, where overflow is well-defined */
- s64 res = (s64)((u64)a - (u64)b);
- if (b < 0)
- return res < a;
- return res > a;
- }
- static bool signed_sub32_overflows(s32 a, s32 b)
- {
- /* Do the sub in u32, where overflow is well-defined */
- s32 res = (s32)((u32)a - (u32)b);
- if (b < 0)
- return res < a;
- return res > a;
- }
- static bool check_reg_sane_offset(struct bpf_verifier_env *env,
- const struct bpf_reg_state *reg,
- enum bpf_reg_type type)
- {
- bool known = tnum_is_const(reg->var_off);
- s64 val = reg->var_off.value;
- s64 smin = reg->smin_value;
- if (known && (val >= BPF_MAX_VAR_OFF || val <= -BPF_MAX_VAR_OFF)) {
- verbose(env, "math between %s pointer and %lld is not allowed\n",
- reg_type_str[type], val);
- return false;
- }
- if (reg->off >= BPF_MAX_VAR_OFF || reg->off <= -BPF_MAX_VAR_OFF) {
- verbose(env, "%s pointer offset %d is not allowed\n",
- reg_type_str[type], reg->off);
- return false;
- }
- if (smin == S64_MIN) {
- verbose(env, "math between %s pointer and register with unbounded min value is not allowed\n",
- reg_type_str[type]);
- return false;
- }
- if (smin >= BPF_MAX_VAR_OFF || smin <= -BPF_MAX_VAR_OFF) {
- verbose(env, "value %lld makes %s pointer be out of bounds\n",
- smin, reg_type_str[type]);
- return false;
- }
- return true;
- }
- static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env)
- {
- return &env->insn_aux_data[env->insn_idx];
- }
- enum {
- REASON_BOUNDS = -1,
- REASON_TYPE = -2,
- REASON_PATHS = -3,
- REASON_LIMIT = -4,
- REASON_STACK = -5,
- };
- static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg,
- u32 *alu_limit, bool mask_to_left)
- {
- u32 max = 0, ptr_limit = 0;
- switch (ptr_reg->type) {
- case PTR_TO_STACK:
- /* Offset 0 is out-of-bounds, but acceptable start for the
- * left direction, see BPF_REG_FP. Also, unknown scalar
- * offset where we would need to deal with min/max bounds is
- * currently prohibited for unprivileged.
- */
- max = MAX_BPF_STACK + mask_to_left;
- ptr_limit = -(ptr_reg->var_off.value + ptr_reg->off);
- break;
- case PTR_TO_MAP_VALUE:
- max = ptr_reg->map_ptr->value_size;
- ptr_limit = (mask_to_left ?
- ptr_reg->smin_value :
- ptr_reg->umax_value) + ptr_reg->off;
- break;
- default:
- return REASON_TYPE;
- }
- if (ptr_limit >= max)
- return REASON_LIMIT;
- *alu_limit = ptr_limit;
- return 0;
- }
- static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env,
- const struct bpf_insn *insn)
- {
- return env->bypass_spec_v1 || BPF_SRC(insn->code) == BPF_K;
- }
- static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux,
- u32 alu_state, u32 alu_limit)
- {
- /* If we arrived here from different branches with different
- * state or limits to sanitize, then this won't work.
- */
- if (aux->alu_state &&
- (aux->alu_state != alu_state ||
- aux->alu_limit != alu_limit))
- return REASON_PATHS;
- /* Corresponding fixup done in fixup_bpf_calls(). */
- aux->alu_state = alu_state;
- aux->alu_limit = alu_limit;
- return 0;
- }
- static int sanitize_val_alu(struct bpf_verifier_env *env,
- struct bpf_insn *insn)
- {
- struct bpf_insn_aux_data *aux = cur_aux(env);
- if (can_skip_alu_sanitation(env, insn))
- return 0;
- return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0);
- }
- static bool sanitize_needed(u8 opcode)
- {
- return opcode == BPF_ADD || opcode == BPF_SUB;
- }
- struct bpf_sanitize_info {
- struct bpf_insn_aux_data aux;
- bool mask_to_left;
- };
- static struct bpf_verifier_state *
- sanitize_speculative_path(struct bpf_verifier_env *env,
- const struct bpf_insn *insn,
- u32 next_idx, u32 curr_idx)
- {
- struct bpf_verifier_state *branch;
- struct bpf_reg_state *regs;
- branch = push_stack(env, next_idx, curr_idx, true);
- if (branch && insn) {
- regs = branch->frame[branch->curframe]->regs;
- if (BPF_SRC(insn->code) == BPF_K) {
- mark_reg_unknown(env, regs, insn->dst_reg);
- } else if (BPF_SRC(insn->code) == BPF_X) {
- mark_reg_unknown(env, regs, insn->dst_reg);
- mark_reg_unknown(env, regs, insn->src_reg);
- }
- }
- return branch;
- }
- static int sanitize_ptr_alu(struct bpf_verifier_env *env,
- struct bpf_insn *insn,
- const struct bpf_reg_state *ptr_reg,
- const struct bpf_reg_state *off_reg,
- struct bpf_reg_state *dst_reg,
- struct bpf_sanitize_info *info,
- const bool commit_window)
- {
- struct bpf_insn_aux_data *aux = commit_window ? cur_aux(env) : &info->aux;
- struct bpf_verifier_state *vstate = env->cur_state;
- bool off_is_imm = tnum_is_const(off_reg->var_off);
- bool off_is_neg = off_reg->smin_value < 0;
- bool ptr_is_dst_reg = ptr_reg == dst_reg;
- u8 opcode = BPF_OP(insn->code);
- u32 alu_state, alu_limit;
- struct bpf_reg_state tmp;
- bool ret;
- int err;
- if (can_skip_alu_sanitation(env, insn))
- return 0;
- /* We already marked aux for masking from non-speculative
- * paths, thus we got here in the first place. We only care
- * to explore bad access from here.
- */
- if (vstate->speculative)
- goto do_sim;
- if (!commit_window) {
- if (!tnum_is_const(off_reg->var_off) &&
- (off_reg->smin_value < 0) != (off_reg->smax_value < 0))
- return REASON_BOUNDS;
- info->mask_to_left = (opcode == BPF_ADD && off_is_neg) ||
- (opcode == BPF_SUB && !off_is_neg);
- }
- err = retrieve_ptr_limit(ptr_reg, &alu_limit, info->mask_to_left);
- if (err < 0)
- return err;
- if (commit_window) {
- /* In commit phase we narrow the masking window based on
- * the observed pointer move after the simulated operation.
- */
- alu_state = info->aux.alu_state;
- alu_limit = abs(info->aux.alu_limit - alu_limit);
- } else {
- alu_state = off_is_neg ? BPF_ALU_NEG_VALUE : 0;
- alu_state |= off_is_imm ? BPF_ALU_IMMEDIATE : 0;
- alu_state |= ptr_is_dst_reg ?
- BPF_ALU_SANITIZE_SRC : BPF_ALU_SANITIZE_DST;
- /* Limit pruning on unknown scalars to enable deep search for
- * potential masking differences from other program paths.
- */
- if (!off_is_imm)
- env->explore_alu_limits = true;
- }
- err = update_alu_sanitation_state(aux, alu_state, alu_limit);
- if (err < 0)
- return err;
- do_sim:
- /* If we're in commit phase, we're done here given we already
- * pushed the truncated dst_reg into the speculative verification
- * stack.
- *
- * Also, when register is a known constant, we rewrite register-based
- * operation to immediate-based, and thus do not need masking (and as
- * a consequence, do not need to simulate the zero-truncation either).
- */
- if (commit_window || off_is_imm)
- return 0;
- /* Simulate and find potential out-of-bounds access under
- * speculative execution from truncation as a result of
- * masking when off was not within expected range. If off
- * sits in dst, then we temporarily need to move ptr there
- * to simulate dst (== 0) +/-= ptr. Needed, for example,
- * for cases where we use K-based arithmetic in one direction
- * and truncated reg-based in the other in order to explore
- * bad access.
- */
- if (!ptr_is_dst_reg) {
- tmp = *dst_reg;
- *dst_reg = *ptr_reg;
- }
- ret = sanitize_speculative_path(env, NULL, env->insn_idx + 1,
- env->insn_idx);
- if (!ptr_is_dst_reg && ret)
- *dst_reg = tmp;
- return !ret ? REASON_STACK : 0;
- }
- static void sanitize_mark_insn_seen(struct bpf_verifier_env *env)
- {
- struct bpf_verifier_state *vstate = env->cur_state;
- /* If we simulate paths under speculation, we don't update the
- * insn as 'seen' such that when we verify unreachable paths in
- * the non-speculative domain, sanitize_dead_code() can still
- * rewrite/sanitize them.
- */
- if (!vstate->speculative)
- env->insn_aux_data[env->insn_idx].seen = env->pass_cnt;
- }
- static int sanitize_err(struct bpf_verifier_env *env,
- const struct bpf_insn *insn, int reason,
- const struct bpf_reg_state *off_reg,
- const struct bpf_reg_state *dst_reg)
- {
- static const char *err = "pointer arithmetic with it prohibited for !root";
- const char *op = BPF_OP(insn->code) == BPF_ADD ? "add" : "sub";
- u32 dst = insn->dst_reg, src = insn->src_reg;
- switch (reason) {
- case REASON_BOUNDS:
- verbose(env, "R%d has unknown scalar with mixed signed bounds, %s\n",
- off_reg == dst_reg ? dst : src, err);
- break;
- case REASON_TYPE:
- verbose(env, "R%d has pointer with unsupported alu operation, %s\n",
- off_reg == dst_reg ? src : dst, err);
- break;
- case REASON_PATHS:
- verbose(env, "R%d tried to %s from different maps, paths or scalars, %s\n",
- dst, op, err);
- break;
- case REASON_LIMIT:
- verbose(env, "R%d tried to %s beyond pointer bounds, %s\n",
- dst, op, err);
- break;
- case REASON_STACK:
- verbose(env, "R%d could not be pushed for speculative verification, %s\n",
- dst, err);
- break;
- default:
- verbose(env, "verifier internal error: unknown reason (%d)\n",
- reason);
- break;
- }
- return -EACCES;
- }
- /* check that stack access falls within stack limits and that 'reg' doesn't
- * have a variable offset.
- *
- * Variable offset is prohibited for unprivileged mode for simplicity since it
- * requires corresponding support in Spectre masking for stack ALU. See also
- * retrieve_ptr_limit().
- *
- *
- * 'off' includes 'reg->off'.
- */
- static int check_stack_access_for_ptr_arithmetic(
- struct bpf_verifier_env *env,
- int regno,
- const struct bpf_reg_state *reg,
- int off)
- {
- if (!tnum_is_const(reg->var_off)) {
- char tn_buf[48];
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env, "R%d variable stack access prohibited for !root, var_off=%s off=%d\n",
- regno, tn_buf, off);
- return -EACCES;
- }
- if (off >= 0 || off < -MAX_BPF_STACK) {
- verbose(env, "R%d stack pointer arithmetic goes out of range, "
- "prohibited for !root; off=%d\n", regno, off);
- return -EACCES;
- }
- return 0;
- }
- static int sanitize_check_bounds(struct bpf_verifier_env *env,
- const struct bpf_insn *insn,
- const struct bpf_reg_state *dst_reg)
- {
- u32 dst = insn->dst_reg;
- /* For unprivileged we require that resulting offset must be in bounds
- * in order to be able to sanitize access later on.
- */
- if (env->bypass_spec_v1)
- return 0;
- switch (dst_reg->type) {
- case PTR_TO_STACK:
- if (check_stack_access_for_ptr_arithmetic(env, dst, dst_reg,
- dst_reg->off + dst_reg->var_off.value))
- return -EACCES;
- break;
- case PTR_TO_MAP_VALUE:
- if (check_map_access(env, dst, dst_reg->off, 1, false)) {
- verbose(env, "R%d pointer arithmetic of map value goes out of range, "
- "prohibited for !root\n", dst);
- return -EACCES;
- }
- break;
- default:
- break;
- }
- return 0;
- }
- /* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off.
- * Caller should also handle BPF_MOV case separately.
- * If we return -EACCES, caller may want to try again treating pointer as a
- * scalar. So we only emit a diagnostic if !env->allow_ptr_leaks.
- */
- static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
- struct bpf_insn *insn,
- const struct bpf_reg_state *ptr_reg,
- const struct bpf_reg_state *off_reg)
- {
- struct bpf_verifier_state *vstate = env->cur_state;
- struct bpf_func_state *state = vstate->frame[vstate->curframe];
- struct bpf_reg_state *regs = state->regs, *dst_reg;
- bool known = tnum_is_const(off_reg->var_off);
- s64 smin_val = off_reg->smin_value, smax_val = off_reg->smax_value,
- smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value;
- u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value,
- umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value;
- struct bpf_sanitize_info info = {};
- u8 opcode = BPF_OP(insn->code);
- u32 dst = insn->dst_reg;
- int ret;
- dst_reg = ®s[dst];
- if ((known && (smin_val != smax_val || umin_val != umax_val)) ||
- smin_val > smax_val || umin_val > umax_val) {
- /* Taint dst register if offset had invalid bounds derived from
- * e.g. dead branches.
- */
- __mark_reg_unknown(env, dst_reg);
- return 0;
- }
- if (BPF_CLASS(insn->code) != BPF_ALU64) {
- /* 32-bit ALU ops on pointers produce (meaningless) scalars */
- if (opcode == BPF_SUB && env->allow_ptr_leaks) {
- __mark_reg_unknown(env, dst_reg);
- return 0;
- }
- verbose(env,
- "R%d 32-bit pointer arithmetic prohibited\n",
- dst);
- return -EACCES;
- }
- switch (ptr_reg->type) {
- case PTR_TO_MAP_VALUE_OR_NULL:
- verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n",
- dst, reg_type_str[ptr_reg->type]);
- return -EACCES;
- case CONST_PTR_TO_MAP:
- /* smin_val represents the known value */
- if (known && smin_val == 0 && opcode == BPF_ADD)
- break;
- fallthrough;
- case PTR_TO_PACKET_END:
- case PTR_TO_SOCKET:
- case PTR_TO_SOCK_COMMON:
- case PTR_TO_TCP_SOCK:
- case PTR_TO_XDP_SOCK:
- reject:
- verbose(env, "R%d pointer arithmetic on %s prohibited\n",
- dst, reg_type_str[ptr_reg->type]);
- return -EACCES;
- default:
- if (reg_type_may_be_null(ptr_reg->type))
- goto reject;
- break;
- }
- /* In case of 'scalar += pointer', dst_reg inherits pointer type and id.
- * The id may be overwritten later if we create a new variable offset.
- */
- dst_reg->type = ptr_reg->type;
- dst_reg->id = ptr_reg->id;
- if (!check_reg_sane_offset(env, off_reg, ptr_reg->type) ||
- !check_reg_sane_offset(env, ptr_reg, ptr_reg->type))
- return -EINVAL;
- /* pointer types do not carry 32-bit bounds at the moment. */
- __mark_reg32_unbounded(dst_reg);
- if (sanitize_needed(opcode)) {
- ret = sanitize_ptr_alu(env, insn, ptr_reg, off_reg, dst_reg,
- &info, false);
- if (ret < 0)
- return sanitize_err(env, insn, ret, off_reg, dst_reg);
- }
- switch (opcode) {
- case BPF_ADD:
- /* We can take a fixed offset as long as it doesn't overflow
- * the s32 'off' field
- */
- if (known && (ptr_reg->off + smin_val ==
- (s64)(s32)(ptr_reg->off + smin_val))) {
- /* pointer += K. Accumulate it into fixed offset */
- dst_reg->smin_value = smin_ptr;
- dst_reg->smax_value = smax_ptr;
- dst_reg->umin_value = umin_ptr;
- dst_reg->umax_value = umax_ptr;
- dst_reg->var_off = ptr_reg->var_off;
- dst_reg->off = ptr_reg->off + smin_val;
- dst_reg->raw = ptr_reg->raw;
- break;
- }
- /* A new variable offset is created. Note that off_reg->off
- * == 0, since it's a scalar.
- * dst_reg gets the pointer type and since some positive
- * integer value was added to the pointer, give it a new 'id'
- * if it's a PTR_TO_PACKET.
- * this creates a new 'base' pointer, off_reg (variable) gets
- * added into the variable offset, and we copy the fixed offset
- * from ptr_reg.
- */
- if (signed_add_overflows(smin_ptr, smin_val) ||
- signed_add_overflows(smax_ptr, smax_val)) {
- dst_reg->smin_value = S64_MIN;
- dst_reg->smax_value = S64_MAX;
- } else {
- dst_reg->smin_value = smin_ptr + smin_val;
- dst_reg->smax_value = smax_ptr + smax_val;
- }
- if (umin_ptr + umin_val < umin_ptr ||
- umax_ptr + umax_val < umax_ptr) {
- dst_reg->umin_value = 0;
- dst_reg->umax_value = U64_MAX;
- } else {
- dst_reg->umin_value = umin_ptr + umin_val;
- dst_reg->umax_value = umax_ptr + umax_val;
- }
- dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off);
- dst_reg->off = ptr_reg->off;
- dst_reg->raw = ptr_reg->raw;
- if (reg_is_pkt_pointer(ptr_reg)) {
- dst_reg->id = ++env->id_gen;
- /* something was added to pkt_ptr, set range to zero */
- dst_reg->raw = 0;
- }
- break;
- case BPF_SUB:
- if (dst_reg == off_reg) {
- /* scalar -= pointer. Creates an unknown scalar */
- verbose(env, "R%d tried to subtract pointer from scalar\n",
- dst);
- return -EACCES;
- }
- /* We don't allow subtraction from FP, because (according to
- * test_verifier.c test "invalid fp arithmetic", JITs might not
- * be able to deal with it.
- */
- if (ptr_reg->type == PTR_TO_STACK) {
- verbose(env, "R%d subtraction from stack pointer prohibited\n",
- dst);
- return -EACCES;
- }
- if (known && (ptr_reg->off - smin_val ==
- (s64)(s32)(ptr_reg->off - smin_val))) {
- /* pointer -= K. Subtract it from fixed offset */
- dst_reg->smin_value = smin_ptr;
- dst_reg->smax_value = smax_ptr;
- dst_reg->umin_value = umin_ptr;
- dst_reg->umax_value = umax_ptr;
- dst_reg->var_off = ptr_reg->var_off;
- dst_reg->id = ptr_reg->id;
- dst_reg->off = ptr_reg->off - smin_val;
- dst_reg->raw = ptr_reg->raw;
- break;
- }
- /* A new variable offset is created. If the subtrahend is known
- * nonnegative, then any reg->range we had before is still good.
- */
- if (signed_sub_overflows(smin_ptr, smax_val) ||
- signed_sub_overflows(smax_ptr, smin_val)) {
- /* Overflow possible, we know nothing */
- dst_reg->smin_value = S64_MIN;
- dst_reg->smax_value = S64_MAX;
- } else {
- dst_reg->smin_value = smin_ptr - smax_val;
- dst_reg->smax_value = smax_ptr - smin_val;
- }
- if (umin_ptr < umax_val) {
- /* Overflow possible, we know nothing */
- dst_reg->umin_value = 0;
- dst_reg->umax_value = U64_MAX;
- } else {
- /* Cannot overflow (as long as bounds are consistent) */
- dst_reg->umin_value = umin_ptr - umax_val;
- dst_reg->umax_value = umax_ptr - umin_val;
- }
- dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off);
- dst_reg->off = ptr_reg->off;
- dst_reg->raw = ptr_reg->raw;
- if (reg_is_pkt_pointer(ptr_reg)) {
- dst_reg->id = ++env->id_gen;
- /* something was added to pkt_ptr, set range to zero */
- if (smin_val < 0)
- dst_reg->raw = 0;
- }
- break;
- case BPF_AND:
- case BPF_OR:
- case BPF_XOR:
- /* bitwise ops on pointers are troublesome, prohibit. */
- verbose(env, "R%d bitwise operator %s on pointer prohibited\n",
- dst, bpf_alu_string[opcode >> 4]);
- return -EACCES;
- default:
- /* other operators (e.g. MUL,LSH) produce non-pointer results */
- verbose(env, "R%d pointer arithmetic with %s operator prohibited\n",
- dst, bpf_alu_string[opcode >> 4]);
- return -EACCES;
- }
- if (!check_reg_sane_offset(env, dst_reg, ptr_reg->type))
- return -EINVAL;
- __update_reg_bounds(dst_reg);
- __reg_deduce_bounds(dst_reg);
- __reg_bound_offset(dst_reg);
- if (sanitize_check_bounds(env, insn, dst_reg) < 0)
- return -EACCES;
- if (sanitize_needed(opcode)) {
- ret = sanitize_ptr_alu(env, insn, dst_reg, off_reg, dst_reg,
- &info, true);
- if (ret < 0)
- return sanitize_err(env, insn, ret, off_reg, dst_reg);
- }
- return 0;
- }
- static void scalar32_min_max_add(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- s32 smin_val = src_reg->s32_min_value;
- s32 smax_val = src_reg->s32_max_value;
- u32 umin_val = src_reg->u32_min_value;
- u32 umax_val = src_reg->u32_max_value;
- if (signed_add32_overflows(dst_reg->s32_min_value, smin_val) ||
- signed_add32_overflows(dst_reg->s32_max_value, smax_val)) {
- dst_reg->s32_min_value = S32_MIN;
- dst_reg->s32_max_value = S32_MAX;
- } else {
- dst_reg->s32_min_value += smin_val;
- dst_reg->s32_max_value += smax_val;
- }
- if (dst_reg->u32_min_value + umin_val < umin_val ||
- dst_reg->u32_max_value + umax_val < umax_val) {
- dst_reg->u32_min_value = 0;
- dst_reg->u32_max_value = U32_MAX;
- } else {
- dst_reg->u32_min_value += umin_val;
- dst_reg->u32_max_value += umax_val;
- }
- }
- static void scalar_min_max_add(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- s64 smin_val = src_reg->smin_value;
- s64 smax_val = src_reg->smax_value;
- u64 umin_val = src_reg->umin_value;
- u64 umax_val = src_reg->umax_value;
- if (signed_add_overflows(dst_reg->smin_value, smin_val) ||
- signed_add_overflows(dst_reg->smax_value, smax_val)) {
- dst_reg->smin_value = S64_MIN;
- dst_reg->smax_value = S64_MAX;
- } else {
- dst_reg->smin_value += smin_val;
- dst_reg->smax_value += smax_val;
- }
- if (dst_reg->umin_value + umin_val < umin_val ||
- dst_reg->umax_value + umax_val < umax_val) {
- dst_reg->umin_value = 0;
- dst_reg->umax_value = U64_MAX;
- } else {
- dst_reg->umin_value += umin_val;
- dst_reg->umax_value += umax_val;
- }
- }
- static void scalar32_min_max_sub(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- s32 smin_val = src_reg->s32_min_value;
- s32 smax_val = src_reg->s32_max_value;
- u32 umin_val = src_reg->u32_min_value;
- u32 umax_val = src_reg->u32_max_value;
- if (signed_sub32_overflows(dst_reg->s32_min_value, smax_val) ||
- signed_sub32_overflows(dst_reg->s32_max_value, smin_val)) {
- /* Overflow possible, we know nothing */
- dst_reg->s32_min_value = S32_MIN;
- dst_reg->s32_max_value = S32_MAX;
- } else {
- dst_reg->s32_min_value -= smax_val;
- dst_reg->s32_max_value -= smin_val;
- }
- if (dst_reg->u32_min_value < umax_val) {
- /* Overflow possible, we know nothing */
- dst_reg->u32_min_value = 0;
- dst_reg->u32_max_value = U32_MAX;
- } else {
- /* Cannot overflow (as long as bounds are consistent) */
- dst_reg->u32_min_value -= umax_val;
- dst_reg->u32_max_value -= umin_val;
- }
- }
- static void scalar_min_max_sub(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- s64 smin_val = src_reg->smin_value;
- s64 smax_val = src_reg->smax_value;
- u64 umin_val = src_reg->umin_value;
- u64 umax_val = src_reg->umax_value;
- if (signed_sub_overflows(dst_reg->smin_value, smax_val) ||
- signed_sub_overflows(dst_reg->smax_value, smin_val)) {
- /* Overflow possible, we know nothing */
- dst_reg->smin_value = S64_MIN;
- dst_reg->smax_value = S64_MAX;
- } else {
- dst_reg->smin_value -= smax_val;
- dst_reg->smax_value -= smin_val;
- }
- if (dst_reg->umin_value < umax_val) {
- /* Overflow possible, we know nothing */
- dst_reg->umin_value = 0;
- dst_reg->umax_value = U64_MAX;
- } else {
- /* Cannot overflow (as long as bounds are consistent) */
- dst_reg->umin_value -= umax_val;
- dst_reg->umax_value -= umin_val;
- }
- }
- static void scalar32_min_max_mul(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- s32 smin_val = src_reg->s32_min_value;
- u32 umin_val = src_reg->u32_min_value;
- u32 umax_val = src_reg->u32_max_value;
- if (smin_val < 0 || dst_reg->s32_min_value < 0) {
- /* Ain't nobody got time to multiply that sign */
- __mark_reg32_unbounded(dst_reg);
- return;
- }
- /* Both values are positive, so we can work with unsigned and
- * copy the result to signed (unless it exceeds S32_MAX).
- */
- if (umax_val > U16_MAX || dst_reg->u32_max_value > U16_MAX) {
- /* Potential overflow, we know nothing */
- __mark_reg32_unbounded(dst_reg);
- return;
- }
- dst_reg->u32_min_value *= umin_val;
- dst_reg->u32_max_value *= umax_val;
- if (dst_reg->u32_max_value > S32_MAX) {
- /* Overflow possible, we know nothing */
- dst_reg->s32_min_value = S32_MIN;
- dst_reg->s32_max_value = S32_MAX;
- } else {
- dst_reg->s32_min_value = dst_reg->u32_min_value;
- dst_reg->s32_max_value = dst_reg->u32_max_value;
- }
- }
- static void scalar_min_max_mul(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- s64 smin_val = src_reg->smin_value;
- u64 umin_val = src_reg->umin_value;
- u64 umax_val = src_reg->umax_value;
- if (smin_val < 0 || dst_reg->smin_value < 0) {
- /* Ain't nobody got time to multiply that sign */
- __mark_reg64_unbounded(dst_reg);
- return;
- }
- /* Both values are positive, so we can work with unsigned and
- * copy the result to signed (unless it exceeds S64_MAX).
- */
- if (umax_val > U32_MAX || dst_reg->umax_value > U32_MAX) {
- /* Potential overflow, we know nothing */
- __mark_reg64_unbounded(dst_reg);
- return;
- }
- dst_reg->umin_value *= umin_val;
- dst_reg->umax_value *= umax_val;
- if (dst_reg->umax_value > S64_MAX) {
- /* Overflow possible, we know nothing */
- dst_reg->smin_value = S64_MIN;
- dst_reg->smax_value = S64_MAX;
- } else {
- dst_reg->smin_value = dst_reg->umin_value;
- dst_reg->smax_value = dst_reg->umax_value;
- }
- }
- static void scalar32_min_max_and(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- bool src_known = tnum_subreg_is_const(src_reg->var_off);
- bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
- struct tnum var32_off = tnum_subreg(dst_reg->var_off);
- s32 smin_val = src_reg->s32_min_value;
- u32 umax_val = src_reg->u32_max_value;
- if (src_known && dst_known) {
- __mark_reg32_known(dst_reg, var32_off.value);
- return;
- }
- /* We get our minimum from the var_off, since that's inherently
- * bitwise. Our maximum is the minimum of the operands' maxima.
- */
- dst_reg->u32_min_value = var32_off.value;
- dst_reg->u32_max_value = min(dst_reg->u32_max_value, umax_val);
- if (dst_reg->s32_min_value < 0 || smin_val < 0) {
- /* Lose signed bounds when ANDing negative numbers,
- * ain't nobody got time for that.
- */
- dst_reg->s32_min_value = S32_MIN;
- dst_reg->s32_max_value = S32_MAX;
- } else {
- /* ANDing two positives gives a positive, so safe to
- * cast result into s64.
- */
- dst_reg->s32_min_value = dst_reg->u32_min_value;
- dst_reg->s32_max_value = dst_reg->u32_max_value;
- }
- }
- static void scalar_min_max_and(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- bool src_known = tnum_is_const(src_reg->var_off);
- bool dst_known = tnum_is_const(dst_reg->var_off);
- s64 smin_val = src_reg->smin_value;
- u64 umax_val = src_reg->umax_value;
- if (src_known && dst_known) {
- __mark_reg_known(dst_reg, dst_reg->var_off.value);
- return;
- }
- /* We get our minimum from the var_off, since that's inherently
- * bitwise. Our maximum is the minimum of the operands' maxima.
- */
- dst_reg->umin_value = dst_reg->var_off.value;
- dst_reg->umax_value = min(dst_reg->umax_value, umax_val);
- if (dst_reg->smin_value < 0 || smin_val < 0) {
- /* Lose signed bounds when ANDing negative numbers,
- * ain't nobody got time for that.
- */
- dst_reg->smin_value = S64_MIN;
- dst_reg->smax_value = S64_MAX;
- } else {
- /* ANDing two positives gives a positive, so safe to
- * cast result into s64.
- */
- dst_reg->smin_value = dst_reg->umin_value;
- dst_reg->smax_value = dst_reg->umax_value;
- }
- /* We may learn something more from the var_off */
- __update_reg_bounds(dst_reg);
- }
- static void scalar32_min_max_or(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- bool src_known = tnum_subreg_is_const(src_reg->var_off);
- bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
- struct tnum var32_off = tnum_subreg(dst_reg->var_off);
- s32 smin_val = src_reg->s32_min_value;
- u32 umin_val = src_reg->u32_min_value;
- if (src_known && dst_known) {
- __mark_reg32_known(dst_reg, var32_off.value);
- return;
- }
- /* We get our maximum from the var_off, and our minimum is the
- * maximum of the operands' minima
- */
- dst_reg->u32_min_value = max(dst_reg->u32_min_value, umin_val);
- dst_reg->u32_max_value = var32_off.value | var32_off.mask;
- if (dst_reg->s32_min_value < 0 || smin_val < 0) {
- /* Lose signed bounds when ORing negative numbers,
- * ain't nobody got time for that.
- */
- dst_reg->s32_min_value = S32_MIN;
- dst_reg->s32_max_value = S32_MAX;
- } else {
- /* ORing two positives gives a positive, so safe to
- * cast result into s64.
- */
- dst_reg->s32_min_value = dst_reg->u32_min_value;
- dst_reg->s32_max_value = dst_reg->u32_max_value;
- }
- }
- static void scalar_min_max_or(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- bool src_known = tnum_is_const(src_reg->var_off);
- bool dst_known = tnum_is_const(dst_reg->var_off);
- s64 smin_val = src_reg->smin_value;
- u64 umin_val = src_reg->umin_value;
- if (src_known && dst_known) {
- __mark_reg_known(dst_reg, dst_reg->var_off.value);
- return;
- }
- /* We get our maximum from the var_off, and our minimum is the
- * maximum of the operands' minima
- */
- dst_reg->umin_value = max(dst_reg->umin_value, umin_val);
- dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;
- if (dst_reg->smin_value < 0 || smin_val < 0) {
- /* Lose signed bounds when ORing negative numbers,
- * ain't nobody got time for that.
- */
- dst_reg->smin_value = S64_MIN;
- dst_reg->smax_value = S64_MAX;
- } else {
- /* ORing two positives gives a positive, so safe to
- * cast result into s64.
- */
- dst_reg->smin_value = dst_reg->umin_value;
- dst_reg->smax_value = dst_reg->umax_value;
- }
- /* We may learn something more from the var_off */
- __update_reg_bounds(dst_reg);
- }
- static void scalar32_min_max_xor(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- bool src_known = tnum_subreg_is_const(src_reg->var_off);
- bool dst_known = tnum_subreg_is_const(dst_reg->var_off);
- struct tnum var32_off = tnum_subreg(dst_reg->var_off);
- s32 smin_val = src_reg->s32_min_value;
- if (src_known && dst_known) {
- __mark_reg32_known(dst_reg, var32_off.value);
- return;
- }
- /* We get both minimum and maximum from the var32_off. */
- dst_reg->u32_min_value = var32_off.value;
- dst_reg->u32_max_value = var32_off.value | var32_off.mask;
- if (dst_reg->s32_min_value >= 0 && smin_val >= 0) {
- /* XORing two positive sign numbers gives a positive,
- * so safe to cast u32 result into s32.
- */
- dst_reg->s32_min_value = dst_reg->u32_min_value;
- dst_reg->s32_max_value = dst_reg->u32_max_value;
- } else {
- dst_reg->s32_min_value = S32_MIN;
- dst_reg->s32_max_value = S32_MAX;
- }
- }
- static void scalar_min_max_xor(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- bool src_known = tnum_is_const(src_reg->var_off);
- bool dst_known = tnum_is_const(dst_reg->var_off);
- s64 smin_val = src_reg->smin_value;
- if (src_known && dst_known) {
- /* dst_reg->var_off.value has been updated earlier */
- __mark_reg_known(dst_reg, dst_reg->var_off.value);
- return;
- }
- /* We get both minimum and maximum from the var_off. */
- dst_reg->umin_value = dst_reg->var_off.value;
- dst_reg->umax_value = dst_reg->var_off.value | dst_reg->var_off.mask;
- if (dst_reg->smin_value >= 0 && smin_val >= 0) {
- /* XORing two positive sign numbers gives a positive,
- * so safe to cast u64 result into s64.
- */
- dst_reg->smin_value = dst_reg->umin_value;
- dst_reg->smax_value = dst_reg->umax_value;
- } else {
- dst_reg->smin_value = S64_MIN;
- dst_reg->smax_value = S64_MAX;
- }
- __update_reg_bounds(dst_reg);
- }
- static void __scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
- u64 umin_val, u64 umax_val)
- {
- /* We lose all sign bit information (except what we can pick
- * up from var_off)
- */
- dst_reg->s32_min_value = S32_MIN;
- dst_reg->s32_max_value = S32_MAX;
- /* If we might shift our top bit out, then we know nothing */
- if (umax_val > 31 || dst_reg->u32_max_value > 1ULL << (31 - umax_val)) {
- dst_reg->u32_min_value = 0;
- dst_reg->u32_max_value = U32_MAX;
- } else {
- dst_reg->u32_min_value <<= umin_val;
- dst_reg->u32_max_value <<= umax_val;
- }
- }
- static void scalar32_min_max_lsh(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- u32 umax_val = src_reg->u32_max_value;
- u32 umin_val = src_reg->u32_min_value;
- /* u32 alu operation will zext upper bits */
- struct tnum subreg = tnum_subreg(dst_reg->var_off);
- __scalar32_min_max_lsh(dst_reg, umin_val, umax_val);
- dst_reg->var_off = tnum_subreg(tnum_lshift(subreg, umin_val));
- /* Not required but being careful mark reg64 bounds as unknown so
- * that we are forced to pick them up from tnum and zext later and
- * if some path skips this step we are still safe.
- */
- __mark_reg64_unbounded(dst_reg);
- __update_reg32_bounds(dst_reg);
- }
- static void __scalar64_min_max_lsh(struct bpf_reg_state *dst_reg,
- u64 umin_val, u64 umax_val)
- {
- /* Special case <<32 because it is a common compiler pattern to sign
- * extend subreg by doing <<32 s>>32. In this case if 32bit bounds are
- * positive we know this shift will also be positive so we can track
- * bounds correctly. Otherwise we lose all sign bit information except
- * what we can pick up from var_off. Perhaps we can generalize this
- * later to shifts of any length.
- */
- if (umin_val == 32 && umax_val == 32 && dst_reg->s32_max_value >= 0)
- dst_reg->smax_value = (s64)dst_reg->s32_max_value << 32;
- else
- dst_reg->smax_value = S64_MAX;
- if (umin_val == 32 && umax_val == 32 && dst_reg->s32_min_value >= 0)
- dst_reg->smin_value = (s64)dst_reg->s32_min_value << 32;
- else
- dst_reg->smin_value = S64_MIN;
- /* If we might shift our top bit out, then we know nothing */
- if (dst_reg->umax_value > 1ULL << (63 - umax_val)) {
- dst_reg->umin_value = 0;
- dst_reg->umax_value = U64_MAX;
- } else {
- dst_reg->umin_value <<= umin_val;
- dst_reg->umax_value <<= umax_val;
- }
- }
- static void scalar_min_max_lsh(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- u64 umax_val = src_reg->umax_value;
- u64 umin_val = src_reg->umin_value;
- /* scalar64 calc uses 32bit unshifted bounds so must be called first */
- __scalar64_min_max_lsh(dst_reg, umin_val, umax_val);
- __scalar32_min_max_lsh(dst_reg, umin_val, umax_val);
- dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
- /* We may learn something more from the var_off */
- __update_reg_bounds(dst_reg);
- }
- static void scalar32_min_max_rsh(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- struct tnum subreg = tnum_subreg(dst_reg->var_off);
- u32 umax_val = src_reg->u32_max_value;
- u32 umin_val = src_reg->u32_min_value;
- /* BPF_RSH is an unsigned shift. If the value in dst_reg might
- * be negative, then either:
- * 1) src_reg might be zero, so the sign bit of the result is
- * unknown, so we lose our signed bounds
- * 2) it's known negative, thus the unsigned bounds capture the
- * signed bounds
- * 3) the signed bounds cross zero, so they tell us nothing
- * about the result
- * If the value in dst_reg is known nonnegative, then again the
- * unsigned bounts capture the signed bounds.
- * Thus, in all cases it suffices to blow away our signed bounds
- * and rely on inferring new ones from the unsigned bounds and
- * var_off of the result.
- */
- dst_reg->s32_min_value = S32_MIN;
- dst_reg->s32_max_value = S32_MAX;
- dst_reg->var_off = tnum_rshift(subreg, umin_val);
- dst_reg->u32_min_value >>= umax_val;
- dst_reg->u32_max_value >>= umin_val;
- __mark_reg64_unbounded(dst_reg);
- __update_reg32_bounds(dst_reg);
- }
- static void scalar_min_max_rsh(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- u64 umax_val = src_reg->umax_value;
- u64 umin_val = src_reg->umin_value;
- /* BPF_RSH is an unsigned shift. If the value in dst_reg might
- * be negative, then either:
- * 1) src_reg might be zero, so the sign bit of the result is
- * unknown, so we lose our signed bounds
- * 2) it's known negative, thus the unsigned bounds capture the
- * signed bounds
- * 3) the signed bounds cross zero, so they tell us nothing
- * about the result
- * If the value in dst_reg is known nonnegative, then again the
- * unsigned bounts capture the signed bounds.
- * Thus, in all cases it suffices to blow away our signed bounds
- * and rely on inferring new ones from the unsigned bounds and
- * var_off of the result.
- */
- dst_reg->smin_value = S64_MIN;
- dst_reg->smax_value = S64_MAX;
- dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val);
- dst_reg->umin_value >>= umax_val;
- dst_reg->umax_value >>= umin_val;
- /* Its not easy to operate on alu32 bounds here because it depends
- * on bits being shifted in. Take easy way out and mark unbounded
- * so we can recalculate later from tnum.
- */
- __mark_reg32_unbounded(dst_reg);
- __update_reg_bounds(dst_reg);
- }
- static void scalar32_min_max_arsh(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- u64 umin_val = src_reg->u32_min_value;
- /* Upon reaching here, src_known is true and
- * umax_val is equal to umin_val.
- */
- dst_reg->s32_min_value = (u32)(((s32)dst_reg->s32_min_value) >> umin_val);
- dst_reg->s32_max_value = (u32)(((s32)dst_reg->s32_max_value) >> umin_val);
- dst_reg->var_off = tnum_arshift(tnum_subreg(dst_reg->var_off), umin_val, 32);
- /* blow away the dst_reg umin_value/umax_value and rely on
- * dst_reg var_off to refine the result.
- */
- dst_reg->u32_min_value = 0;
- dst_reg->u32_max_value = U32_MAX;
- __mark_reg64_unbounded(dst_reg);
- __update_reg32_bounds(dst_reg);
- }
- static void scalar_min_max_arsh(struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg)
- {
- u64 umin_val = src_reg->umin_value;
- /* Upon reaching here, src_known is true and umax_val is equal
- * to umin_val.
- */
- dst_reg->smin_value >>= umin_val;
- dst_reg->smax_value >>= umin_val;
- dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val, 64);
- /* blow away the dst_reg umin_value/umax_value and rely on
- * dst_reg var_off to refine the result.
- */
- dst_reg->umin_value = 0;
- dst_reg->umax_value = U64_MAX;
- /* Its not easy to operate on alu32 bounds here because it depends
- * on bits being shifted in from upper 32-bits. Take easy way out
- * and mark unbounded so we can recalculate later from tnum.
- */
- __mark_reg32_unbounded(dst_reg);
- __update_reg_bounds(dst_reg);
- }
- /* WARNING: This function does calculations on 64-bit values, but the actual
- * execution may occur on 32-bit values. Therefore, things like bitshifts
- * need extra checks in the 32-bit case.
- */
- static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
- struct bpf_insn *insn,
- struct bpf_reg_state *dst_reg,
- struct bpf_reg_state src_reg)
- {
- struct bpf_reg_state *regs = cur_regs(env);
- u8 opcode = BPF_OP(insn->code);
- bool src_known;
- s64 smin_val, smax_val;
- u64 umin_val, umax_val;
- s32 s32_min_val, s32_max_val;
- u32 u32_min_val, u32_max_val;
- u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32;
- bool alu32 = (BPF_CLASS(insn->code) != BPF_ALU64);
- int ret;
- smin_val = src_reg.smin_value;
- smax_val = src_reg.smax_value;
- umin_val = src_reg.umin_value;
- umax_val = src_reg.umax_value;
- s32_min_val = src_reg.s32_min_value;
- s32_max_val = src_reg.s32_max_value;
- u32_min_val = src_reg.u32_min_value;
- u32_max_val = src_reg.u32_max_value;
- if (alu32) {
- src_known = tnum_subreg_is_const(src_reg.var_off);
- if ((src_known &&
- (s32_min_val != s32_max_val || u32_min_val != u32_max_val)) ||
- s32_min_val > s32_max_val || u32_min_val > u32_max_val) {
- /* Taint dst register if offset had invalid bounds
- * derived from e.g. dead branches.
- */
- __mark_reg_unknown(env, dst_reg);
- return 0;
- }
- } else {
- src_known = tnum_is_const(src_reg.var_off);
- if ((src_known &&
- (smin_val != smax_val || umin_val != umax_val)) ||
- smin_val > smax_val || umin_val > umax_val) {
- /* Taint dst register if offset had invalid bounds
- * derived from e.g. dead branches.
- */
- __mark_reg_unknown(env, dst_reg);
- return 0;
- }
- }
- if (!src_known &&
- opcode != BPF_ADD && opcode != BPF_SUB && opcode != BPF_AND) {
- __mark_reg_unknown(env, dst_reg);
- return 0;
- }
- if (sanitize_needed(opcode)) {
- ret = sanitize_val_alu(env, insn);
- if (ret < 0)
- return sanitize_err(env, insn, ret, NULL, NULL);
- }
- /* Calculate sign/unsigned bounds and tnum for alu32 and alu64 bit ops.
- * There are two classes of instructions: The first class we track both
- * alu32 and alu64 sign/unsigned bounds independently this provides the
- * greatest amount of precision when alu operations are mixed with jmp32
- * operations. These operations are BPF_ADD, BPF_SUB, BPF_MUL, BPF_ADD,
- * and BPF_OR. This is possible because these ops have fairly easy to
- * understand and calculate behavior in both 32-bit and 64-bit alu ops.
- * See alu32 verifier tests for examples. The second class of
- * operations, BPF_LSH, BPF_RSH, and BPF_ARSH, however are not so easy
- * with regards to tracking sign/unsigned bounds because the bits may
- * cross subreg boundaries in the alu64 case. When this happens we mark
- * the reg unbounded in the subreg bound space and use the resulting
- * tnum to calculate an approximation of the sign/unsigned bounds.
- */
- switch (opcode) {
- case BPF_ADD:
- scalar32_min_max_add(dst_reg, &src_reg);
- scalar_min_max_add(dst_reg, &src_reg);
- dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
- break;
- case BPF_SUB:
- scalar32_min_max_sub(dst_reg, &src_reg);
- scalar_min_max_sub(dst_reg, &src_reg);
- dst_reg->var_off = tnum_sub(dst_reg->var_off, src_reg.var_off);
- break;
- case BPF_MUL:
- dst_reg->var_off = tnum_mul(dst_reg->var_off, src_reg.var_off);
- scalar32_min_max_mul(dst_reg, &src_reg);
- scalar_min_max_mul(dst_reg, &src_reg);
- break;
- case BPF_AND:
- dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off);
- scalar32_min_max_and(dst_reg, &src_reg);
- scalar_min_max_and(dst_reg, &src_reg);
- break;
- case BPF_OR:
- dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off);
- scalar32_min_max_or(dst_reg, &src_reg);
- scalar_min_max_or(dst_reg, &src_reg);
- break;
- case BPF_XOR:
- dst_reg->var_off = tnum_xor(dst_reg->var_off, src_reg.var_off);
- scalar32_min_max_xor(dst_reg, &src_reg);
- scalar_min_max_xor(dst_reg, &src_reg);
- break;
- case BPF_LSH:
- if (umax_val >= insn_bitness) {
- /* Shifts greater than 31 or 63 are undefined.
- * This includes shifts by a negative number.
- */
- mark_reg_unknown(env, regs, insn->dst_reg);
- break;
- }
- if (alu32)
- scalar32_min_max_lsh(dst_reg, &src_reg);
- else
- scalar_min_max_lsh(dst_reg, &src_reg);
- break;
- case BPF_RSH:
- if (umax_val >= insn_bitness) {
- /* Shifts greater than 31 or 63 are undefined.
- * This includes shifts by a negative number.
- */
- mark_reg_unknown(env, regs, insn->dst_reg);
- break;
- }
- if (alu32)
- scalar32_min_max_rsh(dst_reg, &src_reg);
- else
- scalar_min_max_rsh(dst_reg, &src_reg);
- break;
- case BPF_ARSH:
- if (umax_val >= insn_bitness) {
- /* Shifts greater than 31 or 63 are undefined.
- * This includes shifts by a negative number.
- */
- mark_reg_unknown(env, regs, insn->dst_reg);
- break;
- }
- if (alu32)
- scalar32_min_max_arsh(dst_reg, &src_reg);
- else
- scalar_min_max_arsh(dst_reg, &src_reg);
- break;
- default:
- mark_reg_unknown(env, regs, insn->dst_reg);
- break;
- }
- /* ALU32 ops are zero extended into 64bit register */
- if (alu32)
- zext_32_to_64(dst_reg);
- __update_reg_bounds(dst_reg);
- __reg_deduce_bounds(dst_reg);
- __reg_bound_offset(dst_reg);
- return 0;
- }
- /* Handles ALU ops other than BPF_END, BPF_NEG and BPF_MOV: computes new min/max
- * and var_off.
- */
- static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
- struct bpf_insn *insn)
- {
- struct bpf_verifier_state *vstate = env->cur_state;
- struct bpf_func_state *state = vstate->frame[vstate->curframe];
- struct bpf_reg_state *regs = state->regs, *dst_reg, *src_reg;
- struct bpf_reg_state *ptr_reg = NULL, off_reg = {0};
- u8 opcode = BPF_OP(insn->code);
- int err;
- dst_reg = ®s[insn->dst_reg];
- src_reg = NULL;
- if (dst_reg->type != SCALAR_VALUE)
- ptr_reg = dst_reg;
- else
- /* Make sure ID is cleared otherwise dst_reg min/max could be
- * incorrectly propagated into other registers by find_equal_scalars()
- */
- dst_reg->id = 0;
- if (BPF_SRC(insn->code) == BPF_X) {
- src_reg = ®s[insn->src_reg];
- if (src_reg->type != SCALAR_VALUE) {
- if (dst_reg->type != SCALAR_VALUE) {
- /* Combining two pointers by any ALU op yields
- * an arbitrary scalar. Disallow all math except
- * pointer subtraction
- */
- if (opcode == BPF_SUB && env->allow_ptr_leaks) {
- mark_reg_unknown(env, regs, insn->dst_reg);
- return 0;
- }
- verbose(env, "R%d pointer %s pointer prohibited\n",
- insn->dst_reg,
- bpf_alu_string[opcode >> 4]);
- return -EACCES;
- } else {
- /* scalar += pointer
- * This is legal, but we have to reverse our
- * src/dest handling in computing the range
- */
- err = mark_chain_precision(env, insn->dst_reg);
- if (err)
- return err;
- return adjust_ptr_min_max_vals(env, insn,
- src_reg, dst_reg);
- }
- } else if (ptr_reg) {
- /* pointer += scalar */
- err = mark_chain_precision(env, insn->src_reg);
- if (err)
- return err;
- return adjust_ptr_min_max_vals(env, insn,
- dst_reg, src_reg);
- }
- } else {
- /* Pretend the src is a reg with a known value, since we only
- * need to be able to read from this state.
- */
- off_reg.type = SCALAR_VALUE;
- __mark_reg_known(&off_reg, insn->imm);
- src_reg = &off_reg;
- if (ptr_reg) /* pointer += K */
- return adjust_ptr_min_max_vals(env, insn,
- ptr_reg, src_reg);
- }
- /* Got here implies adding two SCALAR_VALUEs */
- if (WARN_ON_ONCE(ptr_reg)) {
- print_verifier_state(env, state);
- verbose(env, "verifier internal error: unexpected ptr_reg\n");
- return -EINVAL;
- }
- if (WARN_ON(!src_reg)) {
- print_verifier_state(env, state);
- verbose(env, "verifier internal error: no src_reg\n");
- return -EINVAL;
- }
- return adjust_scalar_min_max_vals(env, insn, dst_reg, *src_reg);
- }
- /* check validity of 32-bit and 64-bit arithmetic operations */
- static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
- {
- struct bpf_reg_state *regs = cur_regs(env);
- u8 opcode = BPF_OP(insn->code);
- int err;
- if (opcode == BPF_END || opcode == BPF_NEG) {
- if (opcode == BPF_NEG) {
- if (BPF_SRC(insn->code) != 0 ||
- insn->src_reg != BPF_REG_0 ||
- insn->off != 0 || insn->imm != 0) {
- verbose(env, "BPF_NEG uses reserved fields\n");
- return -EINVAL;
- }
- } else {
- if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
- (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) ||
- BPF_CLASS(insn->code) == BPF_ALU64) {
- verbose(env, "BPF_END uses reserved fields\n");
- return -EINVAL;
- }
- }
- /* check src operand */
- err = check_reg_arg(env, insn->dst_reg, SRC_OP);
- if (err)
- return err;
- if (is_pointer_value(env, insn->dst_reg)) {
- verbose(env, "R%d pointer arithmetic prohibited\n",
- insn->dst_reg);
- return -EACCES;
- }
- /* check dest operand */
- err = check_reg_arg(env, insn->dst_reg, DST_OP);
- if (err)
- return err;
- } else if (opcode == BPF_MOV) {
- if (BPF_SRC(insn->code) == BPF_X) {
- if (insn->imm != 0 || insn->off != 0) {
- verbose(env, "BPF_MOV uses reserved fields\n");
- return -EINVAL;
- }
- /* check src operand */
- err = check_reg_arg(env, insn->src_reg, SRC_OP);
- if (err)
- return err;
- } else {
- if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
- verbose(env, "BPF_MOV uses reserved fields\n");
- return -EINVAL;
- }
- }
- /* check dest operand, mark as required later */
- err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
- if (err)
- return err;
- if (BPF_SRC(insn->code) == BPF_X) {
- struct bpf_reg_state *src_reg = regs + insn->src_reg;
- struct bpf_reg_state *dst_reg = regs + insn->dst_reg;
- if (BPF_CLASS(insn->code) == BPF_ALU64) {
- /* case: R1 = R2
- * copy register state to dest reg
- */
- if (src_reg->type == SCALAR_VALUE && !src_reg->id)
- /* Assign src and dst registers the same ID
- * that will be used by find_equal_scalars()
- * to propagate min/max range.
- */
- src_reg->id = ++env->id_gen;
- *dst_reg = *src_reg;
- dst_reg->live |= REG_LIVE_WRITTEN;
- dst_reg->subreg_def = DEF_NOT_SUBREG;
- } else {
- /* R1 = (u32) R2 */
- if (is_pointer_value(env, insn->src_reg)) {
- verbose(env,
- "R%d partial copy of pointer\n",
- insn->src_reg);
- return -EACCES;
- } else if (src_reg->type == SCALAR_VALUE) {
- *dst_reg = *src_reg;
- /* Make sure ID is cleared otherwise
- * dst_reg min/max could be incorrectly
- * propagated into src_reg by find_equal_scalars()
- */
- dst_reg->id = 0;
- dst_reg->live |= REG_LIVE_WRITTEN;
- dst_reg->subreg_def = env->insn_idx + 1;
- } else {
- mark_reg_unknown(env, regs,
- insn->dst_reg);
- }
- zext_32_to_64(dst_reg);
- __update_reg_bounds(dst_reg);
- __reg_deduce_bounds(dst_reg);
- __reg_bound_offset(dst_reg);
- }
- } else {
- /* case: R = imm
- * remember the value we stored into this reg
- */
- /* clear any state __mark_reg_known doesn't set */
- mark_reg_unknown(env, regs, insn->dst_reg);
- regs[insn->dst_reg].type = SCALAR_VALUE;
- if (BPF_CLASS(insn->code) == BPF_ALU64) {
- __mark_reg_known(regs + insn->dst_reg,
- insn->imm);
- } else {
- __mark_reg_known(regs + insn->dst_reg,
- (u32)insn->imm);
- }
- }
- } else if (opcode > BPF_END) {
- verbose(env, "invalid BPF_ALU opcode %x\n", opcode);
- return -EINVAL;
- } else { /* all other ALU ops: and, sub, xor, add, ... */
- if (BPF_SRC(insn->code) == BPF_X) {
- if (insn->imm != 0 || insn->off != 0) {
- verbose(env, "BPF_ALU uses reserved fields\n");
- return -EINVAL;
- }
- /* check src1 operand */
- err = check_reg_arg(env, insn->src_reg, SRC_OP);
- if (err)
- return err;
- } else {
- if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
- verbose(env, "BPF_ALU uses reserved fields\n");
- return -EINVAL;
- }
- }
- /* check src2 operand */
- err = check_reg_arg(env, insn->dst_reg, SRC_OP);
- if (err)
- return err;
- if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
- BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
- verbose(env, "div by zero\n");
- return -EINVAL;
- }
- if ((opcode == BPF_LSH || opcode == BPF_RSH ||
- opcode == BPF_ARSH) && BPF_SRC(insn->code) == BPF_K) {
- int size = BPF_CLASS(insn->code) == BPF_ALU64 ? 64 : 32;
- if (insn->imm < 0 || insn->imm >= size) {
- verbose(env, "invalid shift %d\n", insn->imm);
- return -EINVAL;
- }
- }
- /* check dest operand */
- err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
- if (err)
- return err;
- return adjust_reg_min_max_vals(env, insn);
- }
- return 0;
- }
- static void __find_good_pkt_pointers(struct bpf_func_state *state,
- struct bpf_reg_state *dst_reg,
- enum bpf_reg_type type, u16 new_range)
- {
- struct bpf_reg_state *reg;
- int i;
- for (i = 0; i < MAX_BPF_REG; i++) {
- reg = &state->regs[i];
- if (reg->type == type && reg->id == dst_reg->id)
- /* keep the maximum range already checked */
- reg->range = max(reg->range, new_range);
- }
- bpf_for_each_spilled_reg(i, state, reg) {
- if (!reg)
- continue;
- if (reg->type == type && reg->id == dst_reg->id)
- reg->range = max(reg->range, new_range);
- }
- }
- static void find_good_pkt_pointers(struct bpf_verifier_state *vstate,
- struct bpf_reg_state *dst_reg,
- enum bpf_reg_type type,
- bool range_right_open)
- {
- u16 new_range;
- int i;
- if (dst_reg->off < 0 ||
- (dst_reg->off == 0 && range_right_open))
- /* This doesn't give us any range */
- return;
- if (dst_reg->umax_value > MAX_PACKET_OFF ||
- dst_reg->umax_value + dst_reg->off > MAX_PACKET_OFF)
- /* Risk of overflow. For instance, ptr + (1<<63) may be less
- * than pkt_end, but that's because it's also less than pkt.
- */
- return;
- new_range = dst_reg->off;
- if (range_right_open)
- new_range++;
- /* Examples for register markings:
- *
- * pkt_data in dst register:
- *
- * r2 = r3;
- * r2 += 8;
- * if (r2 > pkt_end) goto <handle exception>
- * <access okay>
- *
- * r2 = r3;
- * r2 += 8;
- * if (r2 < pkt_end) goto <access okay>
- * <handle exception>
- *
- * Where:
- * r2 == dst_reg, pkt_end == src_reg
- * r2=pkt(id=n,off=8,r=0)
- * r3=pkt(id=n,off=0,r=0)
- *
- * pkt_data in src register:
- *
- * r2 = r3;
- * r2 += 8;
- * if (pkt_end >= r2) goto <access okay>
- * <handle exception>
- *
- * r2 = r3;
- * r2 += 8;
- * if (pkt_end <= r2) goto <handle exception>
- * <access okay>
- *
- * Where:
- * pkt_end == dst_reg, r2 == src_reg
- * r2=pkt(id=n,off=8,r=0)
- * r3=pkt(id=n,off=0,r=0)
- *
- * Find register r3 and mark its range as r3=pkt(id=n,off=0,r=8)
- * or r3=pkt(id=n,off=0,r=8-1), so that range of bytes [r3, r3 + 8)
- * and [r3, r3 + 8-1) respectively is safe to access depending on
- * the check.
- */
- /* If our ids match, then we must have the same max_value. And we
- * don't care about the other reg's fixed offset, since if it's too big
- * the range won't allow anything.
- * dst_reg->off is known < MAX_PACKET_OFF, therefore it fits in a u16.
- */
- for (i = 0; i <= vstate->curframe; i++)
- __find_good_pkt_pointers(vstate->frame[i], dst_reg, type,
- new_range);
- }
- static int is_branch32_taken(struct bpf_reg_state *reg, u32 val, u8 opcode)
- {
- struct tnum subreg = tnum_subreg(reg->var_off);
- s32 sval = (s32)val;
- switch (opcode) {
- case BPF_JEQ:
- if (tnum_is_const(subreg))
- return !!tnum_equals_const(subreg, val);
- break;
- case BPF_JNE:
- if (tnum_is_const(subreg))
- return !tnum_equals_const(subreg, val);
- break;
- case BPF_JSET:
- if ((~subreg.mask & subreg.value) & val)
- return 1;
- if (!((subreg.mask | subreg.value) & val))
- return 0;
- break;
- case BPF_JGT:
- if (reg->u32_min_value > val)
- return 1;
- else if (reg->u32_max_value <= val)
- return 0;
- break;
- case BPF_JSGT:
- if (reg->s32_min_value > sval)
- return 1;
- else if (reg->s32_max_value <= sval)
- return 0;
- break;
- case BPF_JLT:
- if (reg->u32_max_value < val)
- return 1;
- else if (reg->u32_min_value >= val)
- return 0;
- break;
- case BPF_JSLT:
- if (reg->s32_max_value < sval)
- return 1;
- else if (reg->s32_min_value >= sval)
- return 0;
- break;
- case BPF_JGE:
- if (reg->u32_min_value >= val)
- return 1;
- else if (reg->u32_max_value < val)
- return 0;
- break;
- case BPF_JSGE:
- if (reg->s32_min_value >= sval)
- return 1;
- else if (reg->s32_max_value < sval)
- return 0;
- break;
- case BPF_JLE:
- if (reg->u32_max_value <= val)
- return 1;
- else if (reg->u32_min_value > val)
- return 0;
- break;
- case BPF_JSLE:
- if (reg->s32_max_value <= sval)
- return 1;
- else if (reg->s32_min_value > sval)
- return 0;
- break;
- }
- return -1;
- }
- static int is_branch64_taken(struct bpf_reg_state *reg, u64 val, u8 opcode)
- {
- s64 sval = (s64)val;
- switch (opcode) {
- case BPF_JEQ:
- if (tnum_is_const(reg->var_off))
- return !!tnum_equals_const(reg->var_off, val);
- break;
- case BPF_JNE:
- if (tnum_is_const(reg->var_off))
- return !tnum_equals_const(reg->var_off, val);
- break;
- case BPF_JSET:
- if ((~reg->var_off.mask & reg->var_off.value) & val)
- return 1;
- if (!((reg->var_off.mask | reg->var_off.value) & val))
- return 0;
- break;
- case BPF_JGT:
- if (reg->umin_value > val)
- return 1;
- else if (reg->umax_value <= val)
- return 0;
- break;
- case BPF_JSGT:
- if (reg->smin_value > sval)
- return 1;
- else if (reg->smax_value <= sval)
- return 0;
- break;
- case BPF_JLT:
- if (reg->umax_value < val)
- return 1;
- else if (reg->umin_value >= val)
- return 0;
- break;
- case BPF_JSLT:
- if (reg->smax_value < sval)
- return 1;
- else if (reg->smin_value >= sval)
- return 0;
- break;
- case BPF_JGE:
- if (reg->umin_value >= val)
- return 1;
- else if (reg->umax_value < val)
- return 0;
- break;
- case BPF_JSGE:
- if (reg->smin_value >= sval)
- return 1;
- else if (reg->smax_value < sval)
- return 0;
- break;
- case BPF_JLE:
- if (reg->umax_value <= val)
- return 1;
- else if (reg->umin_value > val)
- return 0;
- break;
- case BPF_JSLE:
- if (reg->smax_value <= sval)
- return 1;
- else if (reg->smin_value > sval)
- return 0;
- break;
- }
- return -1;
- }
- /* compute branch direction of the expression "if (reg opcode val) goto target;"
- * and return:
- * 1 - branch will be taken and "goto target" will be executed
- * 0 - branch will not be taken and fall-through to next insn
- * -1 - unknown. Example: "if (reg < 5)" is unknown when register value
- * range [0,10]
- */
- static int is_branch_taken(struct bpf_reg_state *reg, u64 val, u8 opcode,
- bool is_jmp32)
- {
- if (__is_pointer_value(false, reg)) {
- if (!reg_type_not_null(reg->type))
- return -1;
- /* If pointer is valid tests against zero will fail so we can
- * use this to direct branch taken.
- */
- if (val != 0)
- return -1;
- switch (opcode) {
- case BPF_JEQ:
- return 0;
- case BPF_JNE:
- return 1;
- default:
- return -1;
- }
- }
- if (is_jmp32)
- return is_branch32_taken(reg, val, opcode);
- return is_branch64_taken(reg, val, opcode);
- }
- /* Adjusts the register min/max values in the case that the dst_reg is the
- * variable register that we are working on, and src_reg is a constant or we're
- * simply doing a BPF_K check.
- * In JEQ/JNE cases we also adjust the var_off values.
- */
- static void reg_set_min_max(struct bpf_reg_state *true_reg,
- struct bpf_reg_state *false_reg,
- u64 val, u32 val32,
- u8 opcode, bool is_jmp32)
- {
- struct tnum false_32off = tnum_subreg(false_reg->var_off);
- struct tnum false_64off = false_reg->var_off;
- struct tnum true_32off = tnum_subreg(true_reg->var_off);
- struct tnum true_64off = true_reg->var_off;
- s64 sval = (s64)val;
- s32 sval32 = (s32)val32;
- /* If the dst_reg is a pointer, we can't learn anything about its
- * variable offset from the compare (unless src_reg were a pointer into
- * the same object, but we don't bother with that.
- * Since false_reg and true_reg have the same type by construction, we
- * only need to check one of them for pointerness.
- */
- if (__is_pointer_value(false, false_reg))
- return;
- switch (opcode) {
- case BPF_JEQ:
- case BPF_JNE:
- {
- struct bpf_reg_state *reg =
- opcode == BPF_JEQ ? true_reg : false_reg;
- /* JEQ/JNE comparison doesn't change the register equivalence.
- * r1 = r2;
- * if (r1 == 42) goto label;
- * ...
- * label: // here both r1 and r2 are known to be 42.
- *
- * Hence when marking register as known preserve it's ID.
- */
- if (is_jmp32)
- __mark_reg32_known(reg, val32);
- else
- ___mark_reg_known(reg, val);
- break;
- }
- case BPF_JSET:
- if (is_jmp32) {
- false_32off = tnum_and(false_32off, tnum_const(~val32));
- if (is_power_of_2(val32))
- true_32off = tnum_or(true_32off,
- tnum_const(val32));
- } else {
- false_64off = tnum_and(false_64off, tnum_const(~val));
- if (is_power_of_2(val))
- true_64off = tnum_or(true_64off,
- tnum_const(val));
- }
- break;
- case BPF_JGE:
- case BPF_JGT:
- {
- if (is_jmp32) {
- u32 false_umax = opcode == BPF_JGT ? val32 : val32 - 1;
- u32 true_umin = opcode == BPF_JGT ? val32 + 1 : val32;
- false_reg->u32_max_value = min(false_reg->u32_max_value,
- false_umax);
- true_reg->u32_min_value = max(true_reg->u32_min_value,
- true_umin);
- } else {
- u64 false_umax = opcode == BPF_JGT ? val : val - 1;
- u64 true_umin = opcode == BPF_JGT ? val + 1 : val;
- false_reg->umax_value = min(false_reg->umax_value, false_umax);
- true_reg->umin_value = max(true_reg->umin_value, true_umin);
- }
- break;
- }
- case BPF_JSGE:
- case BPF_JSGT:
- {
- if (is_jmp32) {
- s32 false_smax = opcode == BPF_JSGT ? sval32 : sval32 - 1;
- s32 true_smin = opcode == BPF_JSGT ? sval32 + 1 : sval32;
- false_reg->s32_max_value = min(false_reg->s32_max_value, false_smax);
- true_reg->s32_min_value = max(true_reg->s32_min_value, true_smin);
- } else {
- s64 false_smax = opcode == BPF_JSGT ? sval : sval - 1;
- s64 true_smin = opcode == BPF_JSGT ? sval + 1 : sval;
- false_reg->smax_value = min(false_reg->smax_value, false_smax);
- true_reg->smin_value = max(true_reg->smin_value, true_smin);
- }
- break;
- }
- case BPF_JLE:
- case BPF_JLT:
- {
- if (is_jmp32) {
- u32 false_umin = opcode == BPF_JLT ? val32 : val32 + 1;
- u32 true_umax = opcode == BPF_JLT ? val32 - 1 : val32;
- false_reg->u32_min_value = max(false_reg->u32_min_value,
- false_umin);
- true_reg->u32_max_value = min(true_reg->u32_max_value,
- true_umax);
- } else {
- u64 false_umin = opcode == BPF_JLT ? val : val + 1;
- u64 true_umax = opcode == BPF_JLT ? val - 1 : val;
- false_reg->umin_value = max(false_reg->umin_value, false_umin);
- true_reg->umax_value = min(true_reg->umax_value, true_umax);
- }
- break;
- }
- case BPF_JSLE:
- case BPF_JSLT:
- {
- if (is_jmp32) {
- s32 false_smin = opcode == BPF_JSLT ? sval32 : sval32 + 1;
- s32 true_smax = opcode == BPF_JSLT ? sval32 - 1 : sval32;
- false_reg->s32_min_value = max(false_reg->s32_min_value, false_smin);
- true_reg->s32_max_value = min(true_reg->s32_max_value, true_smax);
- } else {
- s64 false_smin = opcode == BPF_JSLT ? sval : sval + 1;
- s64 true_smax = opcode == BPF_JSLT ? sval - 1 : sval;
- false_reg->smin_value = max(false_reg->smin_value, false_smin);
- true_reg->smax_value = min(true_reg->smax_value, true_smax);
- }
- break;
- }
- default:
- return;
- }
- if (is_jmp32) {
- false_reg->var_off = tnum_or(tnum_clear_subreg(false_64off),
- tnum_subreg(false_32off));
- true_reg->var_off = tnum_or(tnum_clear_subreg(true_64off),
- tnum_subreg(true_32off));
- __reg_combine_32_into_64(false_reg);
- __reg_combine_32_into_64(true_reg);
- } else {
- false_reg->var_off = false_64off;
- true_reg->var_off = true_64off;
- __reg_combine_64_into_32(false_reg);
- __reg_combine_64_into_32(true_reg);
- }
- }
- /* Same as above, but for the case that dst_reg holds a constant and src_reg is
- * the variable reg.
- */
- static void reg_set_min_max_inv(struct bpf_reg_state *true_reg,
- struct bpf_reg_state *false_reg,
- u64 val, u32 val32,
- u8 opcode, bool is_jmp32)
- {
- /* How can we transform "a <op> b" into "b <op> a"? */
- static const u8 opcode_flip[16] = {
- /* these stay the same */
- [BPF_JEQ >> 4] = BPF_JEQ,
- [BPF_JNE >> 4] = BPF_JNE,
- [BPF_JSET >> 4] = BPF_JSET,
- /* these swap "lesser" and "greater" (L and G in the opcodes) */
- [BPF_JGE >> 4] = BPF_JLE,
- [BPF_JGT >> 4] = BPF_JLT,
- [BPF_JLE >> 4] = BPF_JGE,
- [BPF_JLT >> 4] = BPF_JGT,
- [BPF_JSGE >> 4] = BPF_JSLE,
- [BPF_JSGT >> 4] = BPF_JSLT,
- [BPF_JSLE >> 4] = BPF_JSGE,
- [BPF_JSLT >> 4] = BPF_JSGT
- };
- opcode = opcode_flip[opcode >> 4];
- /* This uses zero as "not present in table"; luckily the zero opcode,
- * BPF_JA, can't get here.
- */
- if (opcode)
- reg_set_min_max(true_reg, false_reg, val, val32, opcode, is_jmp32);
- }
- /* Regs are known to be equal, so intersect their min/max/var_off */
- static void __reg_combine_min_max(struct bpf_reg_state *src_reg,
- struct bpf_reg_state *dst_reg)
- {
- src_reg->umin_value = dst_reg->umin_value = max(src_reg->umin_value,
- dst_reg->umin_value);
- src_reg->umax_value = dst_reg->umax_value = min(src_reg->umax_value,
- dst_reg->umax_value);
- src_reg->smin_value = dst_reg->smin_value = max(src_reg->smin_value,
- dst_reg->smin_value);
- src_reg->smax_value = dst_reg->smax_value = min(src_reg->smax_value,
- dst_reg->smax_value);
- src_reg->var_off = dst_reg->var_off = tnum_intersect(src_reg->var_off,
- dst_reg->var_off);
- /* We might have learned new bounds from the var_off. */
- __update_reg_bounds(src_reg);
- __update_reg_bounds(dst_reg);
- /* We might have learned something about the sign bit. */
- __reg_deduce_bounds(src_reg);
- __reg_deduce_bounds(dst_reg);
- /* We might have learned some bits from the bounds. */
- __reg_bound_offset(src_reg);
- __reg_bound_offset(dst_reg);
- /* Intersecting with the old var_off might have improved our bounds
- * slightly. e.g. if umax was 0x7f...f and var_off was (0; 0xf...fc),
- * then new var_off is (0; 0x7f...fc) which improves our umax.
- */
- __update_reg_bounds(src_reg);
- __update_reg_bounds(dst_reg);
- }
- static void reg_combine_min_max(struct bpf_reg_state *true_src,
- struct bpf_reg_state *true_dst,
- struct bpf_reg_state *false_src,
- struct bpf_reg_state *false_dst,
- u8 opcode)
- {
- switch (opcode) {
- case BPF_JEQ:
- __reg_combine_min_max(true_src, true_dst);
- break;
- case BPF_JNE:
- __reg_combine_min_max(false_src, false_dst);
- break;
- }
- }
- static void mark_ptr_or_null_reg(struct bpf_func_state *state,
- struct bpf_reg_state *reg, u32 id,
- bool is_null)
- {
- if (reg_type_may_be_null(reg->type) && reg->id == id &&
- !WARN_ON_ONCE(!reg->id)) {
- if (WARN_ON_ONCE(reg->smin_value || reg->smax_value ||
- !tnum_equals_const(reg->var_off, 0) ||
- reg->off)) {
- /* Old offset (both fixed and variable parts) should
- * have been known-zero, because we don't allow pointer
- * arithmetic on pointers that might be NULL. If we
- * see this happening, don't convert the register.
- */
- return;
- }
- if (is_null) {
- reg->type = SCALAR_VALUE;
- } else if (reg->type == PTR_TO_MAP_VALUE_OR_NULL) {
- const struct bpf_map *map = reg->map_ptr;
- if (map->inner_map_meta) {
- reg->type = CONST_PTR_TO_MAP;
- reg->map_ptr = map->inner_map_meta;
- } else if (map->map_type == BPF_MAP_TYPE_XSKMAP) {
- reg->type = PTR_TO_XDP_SOCK;
- } else if (map->map_type == BPF_MAP_TYPE_SOCKMAP ||
- map->map_type == BPF_MAP_TYPE_SOCKHASH) {
- reg->type = PTR_TO_SOCKET;
- } else {
- reg->type = PTR_TO_MAP_VALUE;
- }
- } else if (reg->type == PTR_TO_SOCKET_OR_NULL) {
- reg->type = PTR_TO_SOCKET;
- } else if (reg->type == PTR_TO_SOCK_COMMON_OR_NULL) {
- reg->type = PTR_TO_SOCK_COMMON;
- } else if (reg->type == PTR_TO_TCP_SOCK_OR_NULL) {
- reg->type = PTR_TO_TCP_SOCK;
- } else if (reg->type == PTR_TO_BTF_ID_OR_NULL) {
- reg->type = PTR_TO_BTF_ID;
- } else if (reg->type == PTR_TO_MEM_OR_NULL) {
- reg->type = PTR_TO_MEM;
- } else if (reg->type == PTR_TO_RDONLY_BUF_OR_NULL) {
- reg->type = PTR_TO_RDONLY_BUF;
- } else if (reg->type == PTR_TO_RDWR_BUF_OR_NULL) {
- reg->type = PTR_TO_RDWR_BUF;
- }
- if (is_null) {
- /* We don't need id and ref_obj_id from this point
- * onwards anymore, thus we should better reset it,
- * so that state pruning has chances to take effect.
- */
- reg->id = 0;
- reg->ref_obj_id = 0;
- } else if (!reg_may_point_to_spin_lock(reg)) {
- /* For not-NULL ptr, reg->ref_obj_id will be reset
- * in release_reg_references().
- *
- * reg->id is still used by spin_lock ptr. Other
- * than spin_lock ptr type, reg->id can be reset.
- */
- reg->id = 0;
- }
- }
- }
- static void __mark_ptr_or_null_regs(struct bpf_func_state *state, u32 id,
- bool is_null)
- {
- struct bpf_reg_state *reg;
- int i;
- for (i = 0; i < MAX_BPF_REG; i++)
- mark_ptr_or_null_reg(state, &state->regs[i], id, is_null);
- bpf_for_each_spilled_reg(i, state, reg) {
- if (!reg)
- continue;
- mark_ptr_or_null_reg(state, reg, id, is_null);
- }
- }
- /* The logic is similar to find_good_pkt_pointers(), both could eventually
- * be folded together at some point.
- */
- static void mark_ptr_or_null_regs(struct bpf_verifier_state *vstate, u32 regno,
- bool is_null)
- {
- struct bpf_func_state *state = vstate->frame[vstate->curframe];
- struct bpf_reg_state *regs = state->regs;
- u32 ref_obj_id = regs[regno].ref_obj_id;
- u32 id = regs[regno].id;
- int i;
- if (ref_obj_id && ref_obj_id == id && is_null)
- /* regs[regno] is in the " == NULL" branch.
- * No one could have freed the reference state before
- * doing the NULL check.
- */
- WARN_ON_ONCE(release_reference_state(state, id));
- for (i = 0; i <= vstate->curframe; i++)
- __mark_ptr_or_null_regs(vstate->frame[i], id, is_null);
- }
- static bool try_match_pkt_pointers(const struct bpf_insn *insn,
- struct bpf_reg_state *dst_reg,
- struct bpf_reg_state *src_reg,
- struct bpf_verifier_state *this_branch,
- struct bpf_verifier_state *other_branch)
- {
- if (BPF_SRC(insn->code) != BPF_X)
- return false;
- /* Pointers are always 64-bit. */
- if (BPF_CLASS(insn->code) == BPF_JMP32)
- return false;
- switch (BPF_OP(insn->code)) {
- case BPF_JGT:
- if ((dst_reg->type == PTR_TO_PACKET &&
- src_reg->type == PTR_TO_PACKET_END) ||
- (dst_reg->type == PTR_TO_PACKET_META &&
- reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
- /* pkt_data' > pkt_end, pkt_meta' > pkt_data */
- find_good_pkt_pointers(this_branch, dst_reg,
- dst_reg->type, false);
- } else if ((dst_reg->type == PTR_TO_PACKET_END &&
- src_reg->type == PTR_TO_PACKET) ||
- (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
- src_reg->type == PTR_TO_PACKET_META)) {
- /* pkt_end > pkt_data', pkt_data > pkt_meta' */
- find_good_pkt_pointers(other_branch, src_reg,
- src_reg->type, true);
- } else {
- return false;
- }
- break;
- case BPF_JLT:
- if ((dst_reg->type == PTR_TO_PACKET &&
- src_reg->type == PTR_TO_PACKET_END) ||
- (dst_reg->type == PTR_TO_PACKET_META &&
- reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
- /* pkt_data' < pkt_end, pkt_meta' < pkt_data */
- find_good_pkt_pointers(other_branch, dst_reg,
- dst_reg->type, true);
- } else if ((dst_reg->type == PTR_TO_PACKET_END &&
- src_reg->type == PTR_TO_PACKET) ||
- (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
- src_reg->type == PTR_TO_PACKET_META)) {
- /* pkt_end < pkt_data', pkt_data > pkt_meta' */
- find_good_pkt_pointers(this_branch, src_reg,
- src_reg->type, false);
- } else {
- return false;
- }
- break;
- case BPF_JGE:
- if ((dst_reg->type == PTR_TO_PACKET &&
- src_reg->type == PTR_TO_PACKET_END) ||
- (dst_reg->type == PTR_TO_PACKET_META &&
- reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
- /* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */
- find_good_pkt_pointers(this_branch, dst_reg,
- dst_reg->type, true);
- } else if ((dst_reg->type == PTR_TO_PACKET_END &&
- src_reg->type == PTR_TO_PACKET) ||
- (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
- src_reg->type == PTR_TO_PACKET_META)) {
- /* pkt_end >= pkt_data', pkt_data >= pkt_meta' */
- find_good_pkt_pointers(other_branch, src_reg,
- src_reg->type, false);
- } else {
- return false;
- }
- break;
- case BPF_JLE:
- if ((dst_reg->type == PTR_TO_PACKET &&
- src_reg->type == PTR_TO_PACKET_END) ||
- (dst_reg->type == PTR_TO_PACKET_META &&
- reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
- /* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */
- find_good_pkt_pointers(other_branch, dst_reg,
- dst_reg->type, false);
- } else if ((dst_reg->type == PTR_TO_PACKET_END &&
- src_reg->type == PTR_TO_PACKET) ||
- (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
- src_reg->type == PTR_TO_PACKET_META)) {
- /* pkt_end <= pkt_data', pkt_data <= pkt_meta' */
- find_good_pkt_pointers(this_branch, src_reg,
- src_reg->type, true);
- } else {
- return false;
- }
- break;
- default:
- return false;
- }
- return true;
- }
- static void find_equal_scalars(struct bpf_verifier_state *vstate,
- struct bpf_reg_state *known_reg)
- {
- struct bpf_func_state *state;
- struct bpf_reg_state *reg;
- int i, j;
- for (i = 0; i <= vstate->curframe; i++) {
- state = vstate->frame[i];
- for (j = 0; j < MAX_BPF_REG; j++) {
- reg = &state->regs[j];
- if (reg->type == SCALAR_VALUE && reg->id == known_reg->id)
- *reg = *known_reg;
- }
- bpf_for_each_spilled_reg(j, state, reg) {
- if (!reg)
- continue;
- if (reg->type == SCALAR_VALUE && reg->id == known_reg->id)
- *reg = *known_reg;
- }
- }
- }
- static int check_cond_jmp_op(struct bpf_verifier_env *env,
- struct bpf_insn *insn, int *insn_idx)
- {
- struct bpf_verifier_state *this_branch = env->cur_state;
- struct bpf_verifier_state *other_branch;
- struct bpf_reg_state *regs = this_branch->frame[this_branch->curframe]->regs;
- struct bpf_reg_state *dst_reg, *other_branch_regs, *src_reg = NULL;
- u8 opcode = BPF_OP(insn->code);
- bool is_jmp32;
- int pred = -1;
- int err;
- /* Only conditional jumps are expected to reach here. */
- if (opcode == BPF_JA || opcode > BPF_JSLE) {
- verbose(env, "invalid BPF_JMP/JMP32 opcode %x\n", opcode);
- return -EINVAL;
- }
- if (BPF_SRC(insn->code) == BPF_X) {
- if (insn->imm != 0) {
- verbose(env, "BPF_JMP/JMP32 uses reserved fields\n");
- return -EINVAL;
- }
- /* check src1 operand */
- err = check_reg_arg(env, insn->src_reg, SRC_OP);
- if (err)
- return err;
- if (is_pointer_value(env, insn->src_reg)) {
- verbose(env, "R%d pointer comparison prohibited\n",
- insn->src_reg);
- return -EACCES;
- }
- src_reg = ®s[insn->src_reg];
- } else {
- if (insn->src_reg != BPF_REG_0) {
- verbose(env, "BPF_JMP/JMP32 uses reserved fields\n");
- return -EINVAL;
- }
- }
- /* check src2 operand */
- err = check_reg_arg(env, insn->dst_reg, SRC_OP);
- if (err)
- return err;
- dst_reg = ®s[insn->dst_reg];
- is_jmp32 = BPF_CLASS(insn->code) == BPF_JMP32;
- if (BPF_SRC(insn->code) == BPF_K) {
- pred = is_branch_taken(dst_reg, insn->imm, opcode, is_jmp32);
- } else if (src_reg->type == SCALAR_VALUE &&
- is_jmp32 && tnum_is_const(tnum_subreg(src_reg->var_off))) {
- pred = is_branch_taken(dst_reg,
- tnum_subreg(src_reg->var_off).value,
- opcode,
- is_jmp32);
- } else if (src_reg->type == SCALAR_VALUE &&
- !is_jmp32 && tnum_is_const(src_reg->var_off)) {
- pred = is_branch_taken(dst_reg,
- src_reg->var_off.value,
- opcode,
- is_jmp32);
- }
- if (pred >= 0) {
- /* If we get here with a dst_reg pointer type it is because
- * above is_branch_taken() special cased the 0 comparison.
- */
- if (!__is_pointer_value(false, dst_reg))
- err = mark_chain_precision(env, insn->dst_reg);
- if (BPF_SRC(insn->code) == BPF_X && !err)
- err = mark_chain_precision(env, insn->src_reg);
- if (err)
- return err;
- }
- if (pred == 1) {
- /* Only follow the goto, ignore fall-through. If needed, push
- * the fall-through branch for simulation under speculative
- * execution.
- */
- if (!env->bypass_spec_v1 &&
- !sanitize_speculative_path(env, insn, *insn_idx + 1,
- *insn_idx))
- return -EFAULT;
- *insn_idx += insn->off;
- return 0;
- } else if (pred == 0) {
- /* Only follow the fall-through branch, since that's where the
- * program will go. If needed, push the goto branch for
- * simulation under speculative execution.
- */
- if (!env->bypass_spec_v1 &&
- !sanitize_speculative_path(env, insn,
- *insn_idx + insn->off + 1,
- *insn_idx))
- return -EFAULT;
- return 0;
- }
- other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx,
- false);
- if (!other_branch)
- return -EFAULT;
- other_branch_regs = other_branch->frame[other_branch->curframe]->regs;
- /* detect if we are comparing against a constant value so we can adjust
- * our min/max values for our dst register.
- * this is only legit if both are scalars (or pointers to the same
- * object, I suppose, but we don't support that right now), because
- * otherwise the different base pointers mean the offsets aren't
- * comparable.
- */
- if (BPF_SRC(insn->code) == BPF_X) {
- struct bpf_reg_state *src_reg = ®s[insn->src_reg];
- if (dst_reg->type == SCALAR_VALUE &&
- src_reg->type == SCALAR_VALUE) {
- if (tnum_is_const(src_reg->var_off) ||
- (is_jmp32 &&
- tnum_is_const(tnum_subreg(src_reg->var_off))))
- reg_set_min_max(&other_branch_regs[insn->dst_reg],
- dst_reg,
- src_reg->var_off.value,
- tnum_subreg(src_reg->var_off).value,
- opcode, is_jmp32);
- else if (tnum_is_const(dst_reg->var_off) ||
- (is_jmp32 &&
- tnum_is_const(tnum_subreg(dst_reg->var_off))))
- reg_set_min_max_inv(&other_branch_regs[insn->src_reg],
- src_reg,
- dst_reg->var_off.value,
- tnum_subreg(dst_reg->var_off).value,
- opcode, is_jmp32);
- else if (!is_jmp32 &&
- (opcode == BPF_JEQ || opcode == BPF_JNE))
- /* Comparing for equality, we can combine knowledge */
- reg_combine_min_max(&other_branch_regs[insn->src_reg],
- &other_branch_regs[insn->dst_reg],
- src_reg, dst_reg, opcode);
- if (src_reg->id &&
- !WARN_ON_ONCE(src_reg->id != other_branch_regs[insn->src_reg].id)) {
- find_equal_scalars(this_branch, src_reg);
- find_equal_scalars(other_branch, &other_branch_regs[insn->src_reg]);
- }
- }
- } else if (dst_reg->type == SCALAR_VALUE) {
- reg_set_min_max(&other_branch_regs[insn->dst_reg],
- dst_reg, insn->imm, (u32)insn->imm,
- opcode, is_jmp32);
- }
- if (dst_reg->type == SCALAR_VALUE && dst_reg->id &&
- !WARN_ON_ONCE(dst_reg->id != other_branch_regs[insn->dst_reg].id)) {
- find_equal_scalars(this_branch, dst_reg);
- find_equal_scalars(other_branch, &other_branch_regs[insn->dst_reg]);
- }
- /* detect if R == 0 where R is returned from bpf_map_lookup_elem().
- * NOTE: these optimizations below are related with pointer comparison
- * which will never be JMP32.
- */
- if (!is_jmp32 && BPF_SRC(insn->code) == BPF_K &&
- insn->imm == 0 && (opcode == BPF_JEQ || opcode == BPF_JNE) &&
- reg_type_may_be_null(dst_reg->type)) {
- /* Mark all identical registers in each branch as either
- * safe or unknown depending R == 0 or R != 0 conditional.
- */
- mark_ptr_or_null_regs(this_branch, insn->dst_reg,
- opcode == BPF_JNE);
- mark_ptr_or_null_regs(other_branch, insn->dst_reg,
- opcode == BPF_JEQ);
- } else if (!try_match_pkt_pointers(insn, dst_reg, ®s[insn->src_reg],
- this_branch, other_branch) &&
- is_pointer_value(env, insn->dst_reg)) {
- verbose(env, "R%d pointer comparison prohibited\n",
- insn->dst_reg);
- return -EACCES;
- }
- if (env->log.level & BPF_LOG_LEVEL)
- print_verifier_state(env, this_branch->frame[this_branch->curframe]);
- return 0;
- }
- /* verify BPF_LD_IMM64 instruction */
- static int check_ld_imm(struct bpf_verifier_env *env, struct bpf_insn *insn)
- {
- struct bpf_insn_aux_data *aux = cur_aux(env);
- struct bpf_reg_state *regs = cur_regs(env);
- struct bpf_reg_state *dst_reg;
- struct bpf_map *map;
- int err;
- if (BPF_SIZE(insn->code) != BPF_DW) {
- verbose(env, "invalid BPF_LD_IMM insn\n");
- return -EINVAL;
- }
- if (insn->off != 0) {
- verbose(env, "BPF_LD_IMM64 uses reserved fields\n");
- return -EINVAL;
- }
- err = check_reg_arg(env, insn->dst_reg, DST_OP);
- if (err)
- return err;
- dst_reg = ®s[insn->dst_reg];
- if (insn->src_reg == 0) {
- u64 imm = ((u64)(insn + 1)->imm << 32) | (u32)insn->imm;
- dst_reg->type = SCALAR_VALUE;
- __mark_reg_known(®s[insn->dst_reg], imm);
- return 0;
- }
- if (insn->src_reg == BPF_PSEUDO_BTF_ID) {
- mark_reg_known_zero(env, regs, insn->dst_reg);
- dst_reg->type = aux->btf_var.reg_type;
- switch (dst_reg->type) {
- case PTR_TO_MEM:
- dst_reg->mem_size = aux->btf_var.mem_size;
- break;
- case PTR_TO_BTF_ID:
- case PTR_TO_PERCPU_BTF_ID:
- dst_reg->btf_id = aux->btf_var.btf_id;
- break;
- default:
- verbose(env, "bpf verifier is misconfigured\n");
- return -EFAULT;
- }
- return 0;
- }
- map = env->used_maps[aux->map_index];
- mark_reg_known_zero(env, regs, insn->dst_reg);
- dst_reg->map_ptr = map;
- if (insn->src_reg == BPF_PSEUDO_MAP_VALUE) {
- dst_reg->type = PTR_TO_MAP_VALUE;
- dst_reg->off = aux->map_off;
- if (map_value_has_spin_lock(map))
- dst_reg->id = ++env->id_gen;
- } else if (insn->src_reg == BPF_PSEUDO_MAP_FD) {
- dst_reg->type = CONST_PTR_TO_MAP;
- } else {
- verbose(env, "bpf verifier is misconfigured\n");
- return -EINVAL;
- }
- return 0;
- }
- static bool may_access_skb(enum bpf_prog_type type)
- {
- switch (type) {
- case BPF_PROG_TYPE_SOCKET_FILTER:
- case BPF_PROG_TYPE_SCHED_CLS:
- case BPF_PROG_TYPE_SCHED_ACT:
- return true;
- default:
- return false;
- }
- }
- /* verify safety of LD_ABS|LD_IND instructions:
- * - they can only appear in the programs where ctx == skb
- * - since they are wrappers of function calls, they scratch R1-R5 registers,
- * preserve R6-R9, and store return value into R0
- *
- * Implicit input:
- * ctx == skb == R6 == CTX
- *
- * Explicit input:
- * SRC == any register
- * IMM == 32-bit immediate
- *
- * Output:
- * R0 - 8/16/32-bit skb data converted to cpu endianness
- */
- static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn)
- {
- struct bpf_reg_state *regs = cur_regs(env);
- static const int ctx_reg = BPF_REG_6;
- u8 mode = BPF_MODE(insn->code);
- int i, err;
- if (!may_access_skb(resolve_prog_type(env->prog))) {
- verbose(env, "BPF_LD_[ABS|IND] instructions not allowed for this program type\n");
- return -EINVAL;
- }
- if (!env->ops->gen_ld_abs) {
- verbose(env, "bpf verifier is misconfigured\n");
- return -EINVAL;
- }
- if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
- BPF_SIZE(insn->code) == BPF_DW ||
- (mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
- verbose(env, "BPF_LD_[ABS|IND] uses reserved fields\n");
- return -EINVAL;
- }
- /* check whether implicit source operand (register R6) is readable */
- err = check_reg_arg(env, ctx_reg, SRC_OP);
- if (err)
- return err;
- /* Disallow usage of BPF_LD_[ABS|IND] with reference tracking, as
- * gen_ld_abs() may terminate the program at runtime, leading to
- * reference leak.
- */
- err = check_reference_leak(env);
- if (err) {
- verbose(env, "BPF_LD_[ABS|IND] cannot be mixed with socket references\n");
- return err;
- }
- if (env->cur_state->active_spin_lock) {
- verbose(env, "BPF_LD_[ABS|IND] cannot be used inside bpf_spin_lock-ed region\n");
- return -EINVAL;
- }
- if (regs[ctx_reg].type != PTR_TO_CTX) {
- verbose(env,
- "at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
- return -EINVAL;
- }
- if (mode == BPF_IND) {
- /* check explicit source operand */
- err = check_reg_arg(env, insn->src_reg, SRC_OP);
- if (err)
- return err;
- }
- err = check_ctx_reg(env, ®s[ctx_reg], ctx_reg);
- if (err < 0)
- return err;
- /* reset caller saved regs to unreadable */
- for (i = 0; i < CALLER_SAVED_REGS; i++) {
- mark_reg_not_init(env, regs, caller_saved[i]);
- check_reg_arg(env, caller_saved[i], DST_OP_NO_MARK);
- }
- /* mark destination R0 register as readable, since it contains
- * the value fetched from the packet.
- * Already marked as written above.
- */
- mark_reg_unknown(env, regs, BPF_REG_0);
- /* ld_abs load up to 32-bit skb data. */
- regs[BPF_REG_0].subreg_def = env->insn_idx + 1;
- return 0;
- }
- static int check_return_code(struct bpf_verifier_env *env)
- {
- struct tnum enforce_attach_type_range = tnum_unknown;
- const struct bpf_prog *prog = env->prog;
- struct bpf_reg_state *reg;
- struct tnum range = tnum_range(0, 1);
- enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
- int err;
- const bool is_subprog = env->cur_state->frame[0]->subprogno;
- /* LSM and struct_ops func-ptr's return type could be "void" */
- if (!is_subprog &&
- (prog_type == BPF_PROG_TYPE_STRUCT_OPS ||
- prog_type == BPF_PROG_TYPE_LSM) &&
- !prog->aux->attach_func_proto->type)
- return 0;
- /* eBPF calling convetion is such that R0 is used
- * to return the value from eBPF program.
- * Make sure that it's readable at this time
- * of bpf_exit, which means that program wrote
- * something into it earlier
- */
- err = check_reg_arg(env, BPF_REG_0, SRC_OP);
- if (err)
- return err;
- if (is_pointer_value(env, BPF_REG_0)) {
- verbose(env, "R0 leaks addr as return value\n");
- return -EACCES;
- }
- reg = cur_regs(env) + BPF_REG_0;
- if (is_subprog) {
- if (reg->type != SCALAR_VALUE) {
- verbose(env, "At subprogram exit the register R0 is not a scalar value (%s)\n",
- reg_type_str[reg->type]);
- return -EINVAL;
- }
- return 0;
- }
- switch (prog_type) {
- case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
- if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG ||
- env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG ||
- env->prog->expected_attach_type == BPF_CGROUP_INET4_GETPEERNAME ||
- env->prog->expected_attach_type == BPF_CGROUP_INET6_GETPEERNAME ||
- env->prog->expected_attach_type == BPF_CGROUP_INET4_GETSOCKNAME ||
- env->prog->expected_attach_type == BPF_CGROUP_INET6_GETSOCKNAME)
- range = tnum_range(1, 1);
- break;
- case BPF_PROG_TYPE_CGROUP_SKB:
- if (env->prog->expected_attach_type == BPF_CGROUP_INET_EGRESS) {
- range = tnum_range(0, 3);
- enforce_attach_type_range = tnum_range(2, 3);
- }
- break;
- case BPF_PROG_TYPE_CGROUP_SOCK:
- case BPF_PROG_TYPE_SOCK_OPS:
- case BPF_PROG_TYPE_CGROUP_DEVICE:
- case BPF_PROG_TYPE_CGROUP_SYSCTL:
- case BPF_PROG_TYPE_CGROUP_SOCKOPT:
- break;
- case BPF_PROG_TYPE_RAW_TRACEPOINT:
- if (!env->prog->aux->attach_btf_id)
- return 0;
- range = tnum_const(0);
- break;
- case BPF_PROG_TYPE_TRACING:
- switch (env->prog->expected_attach_type) {
- case BPF_TRACE_FENTRY:
- case BPF_TRACE_FEXIT:
- range = tnum_const(0);
- break;
- case BPF_TRACE_RAW_TP:
- case BPF_MODIFY_RETURN:
- return 0;
- case BPF_TRACE_ITER:
- break;
- default:
- return -ENOTSUPP;
- }
- break;
- case BPF_PROG_TYPE_SK_LOOKUP:
- range = tnum_range(SK_DROP, SK_PASS);
- break;
- case BPF_PROG_TYPE_EXT:
- /* freplace program can return anything as its return value
- * depends on the to-be-replaced kernel func or bpf program.
- */
- default:
- return 0;
- }
- if (reg->type != SCALAR_VALUE) {
- verbose(env, "At program exit the register R0 is not a known value (%s)\n",
- reg_type_str[reg->type]);
- return -EINVAL;
- }
- if (!tnum_in(range, reg->var_off)) {
- char tn_buf[48];
- verbose(env, "At program exit the register R0 ");
- if (!tnum_is_unknown(reg->var_off)) {
- tnum_strn(tn_buf, sizeof(tn_buf), reg->var_off);
- verbose(env, "has value %s", tn_buf);
- } else {
- verbose(env, "has unknown scalar value");
- }
- tnum_strn(tn_buf, sizeof(tn_buf), range);
- verbose(env, " should have been in %s\n", tn_buf);
- return -EINVAL;
- }
- if (!tnum_is_unknown(enforce_attach_type_range) &&
- tnum_in(enforce_attach_type_range, reg->var_off))
- env->prog->enforce_expected_attach_type = 1;
- return 0;
- }
- /* non-recursive DFS pseudo code
- * 1 procedure DFS-iterative(G,v):
- * 2 label v as discovered
- * 3 let S be a stack
- * 4 S.push(v)
- * 5 while S is not empty
- * 6 t <- S.pop()
- * 7 if t is what we're looking for:
- * 8 return t
- * 9 for all edges e in G.adjacentEdges(t) do
- * 10 if edge e is already labelled
- * 11 continue with the next edge
- * 12 w <- G.adjacentVertex(t,e)
- * 13 if vertex w is not discovered and not explored
- * 14 label e as tree-edge
- * 15 label w as discovered
- * 16 S.push(w)
- * 17 continue at 5
- * 18 else if vertex w is discovered
- * 19 label e as back-edge
- * 20 else
- * 21 // vertex w is explored
- * 22 label e as forward- or cross-edge
- * 23 label t as explored
- * 24 S.pop()
- *
- * convention:
- * 0x10 - discovered
- * 0x11 - discovered and fall-through edge labelled
- * 0x12 - discovered and fall-through and branch edges labelled
- * 0x20 - explored
- */
- enum {
- DISCOVERED = 0x10,
- EXPLORED = 0x20,
- FALLTHROUGH = 1,
- BRANCH = 2,
- };
- static u32 state_htab_size(struct bpf_verifier_env *env)
- {
- return env->prog->len;
- }
- static struct bpf_verifier_state_list **explored_state(
- struct bpf_verifier_env *env,
- int idx)
- {
- struct bpf_verifier_state *cur = env->cur_state;
- struct bpf_func_state *state = cur->frame[cur->curframe];
- return &env->explored_states[(idx ^ state->callsite) % state_htab_size(env)];
- }
- static void init_explored_state(struct bpf_verifier_env *env, int idx)
- {
- env->insn_aux_data[idx].prune_point = true;
- }
- /* t, w, e - match pseudo-code above:
- * t - index of current instruction
- * w - next instruction
- * e - edge
- */
- static int push_insn(int t, int w, int e, struct bpf_verifier_env *env,
- bool loop_ok)
- {
- int *insn_stack = env->cfg.insn_stack;
- int *insn_state = env->cfg.insn_state;
- if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
- return 0;
- if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
- return 0;
- if (w < 0 || w >= env->prog->len) {
- verbose_linfo(env, t, "%d: ", t);
- verbose(env, "jump out of range from insn %d to %d\n", t, w);
- return -EINVAL;
- }
- if (e == BRANCH)
- /* mark branch target for state pruning */
- init_explored_state(env, w);
- if (insn_state[w] == 0) {
- /* tree-edge */
- insn_state[t] = DISCOVERED | e;
- insn_state[w] = DISCOVERED;
- if (env->cfg.cur_stack >= env->prog->len)
- return -E2BIG;
- insn_stack[env->cfg.cur_stack++] = w;
- return 1;
- } else if ((insn_state[w] & 0xF0) == DISCOVERED) {
- if (loop_ok && env->bpf_capable)
- return 0;
- verbose_linfo(env, t, "%d: ", t);
- verbose_linfo(env, w, "%d: ", w);
- verbose(env, "back-edge from insn %d to %d\n", t, w);
- return -EINVAL;
- } else if (insn_state[w] == EXPLORED) {
- /* forward- or cross-edge */
- insn_state[t] = DISCOVERED | e;
- } else {
- verbose(env, "insn state internal bug\n");
- return -EFAULT;
- }
- return 0;
- }
- /* non-recursive depth-first-search to detect loops in BPF program
- * loop == back-edge in directed graph
- */
- static int check_cfg(struct bpf_verifier_env *env)
- {
- struct bpf_insn *insns = env->prog->insnsi;
- int insn_cnt = env->prog->len;
- int *insn_stack, *insn_state;
- int ret = 0;
- int i, t;
- insn_state = env->cfg.insn_state = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
- if (!insn_state)
- return -ENOMEM;
- insn_stack = env->cfg.insn_stack = kvcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
- if (!insn_stack) {
- kvfree(insn_state);
- return -ENOMEM;
- }
- insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
- insn_stack[0] = 0; /* 0 is the first instruction */
- env->cfg.cur_stack = 1;
- peek_stack:
- if (env->cfg.cur_stack == 0)
- goto check_state;
- t = insn_stack[env->cfg.cur_stack - 1];
- if (BPF_CLASS(insns[t].code) == BPF_JMP ||
- BPF_CLASS(insns[t].code) == BPF_JMP32) {
- u8 opcode = BPF_OP(insns[t].code);
- if (opcode == BPF_EXIT) {
- goto mark_explored;
- } else if (opcode == BPF_CALL) {
- ret = push_insn(t, t + 1, FALLTHROUGH, env, false);
- if (ret == 1)
- goto peek_stack;
- else if (ret < 0)
- goto err_free;
- if (t + 1 < insn_cnt)
- init_explored_state(env, t + 1);
- if (insns[t].src_reg == BPF_PSEUDO_CALL) {
- init_explored_state(env, t);
- ret = push_insn(t, t + insns[t].imm + 1, BRANCH,
- env, false);
- if (ret == 1)
- goto peek_stack;
- else if (ret < 0)
- goto err_free;
- }
- } else if (opcode == BPF_JA) {
- if (BPF_SRC(insns[t].code) != BPF_K) {
- ret = -EINVAL;
- goto err_free;
- }
- /* unconditional jump with single edge */
- ret = push_insn(t, t + insns[t].off + 1,
- FALLTHROUGH, env, true);
- if (ret == 1)
- goto peek_stack;
- else if (ret < 0)
- goto err_free;
- /* unconditional jmp is not a good pruning point,
- * but it's marked, since backtracking needs
- * to record jmp history in is_state_visited().
- */
- init_explored_state(env, t + insns[t].off + 1);
- /* tell verifier to check for equivalent states
- * after every call and jump
- */
- if (t + 1 < insn_cnt)
- init_explored_state(env, t + 1);
- } else {
- /* conditional jump with two edges */
- init_explored_state(env, t);
- ret = push_insn(t, t + 1, FALLTHROUGH, env, true);
- if (ret == 1)
- goto peek_stack;
- else if (ret < 0)
- goto err_free;
- ret = push_insn(t, t + insns[t].off + 1, BRANCH, env, true);
- if (ret == 1)
- goto peek_stack;
- else if (ret < 0)
- goto err_free;
- }
- } else {
- /* all other non-branch instructions with single
- * fall-through edge
- */
- ret = push_insn(t, t + 1, FALLTHROUGH, env, false);
- if (ret == 1)
- goto peek_stack;
- else if (ret < 0)
- goto err_free;
- }
- mark_explored:
- insn_state[t] = EXPLORED;
- if (env->cfg.cur_stack-- <= 0) {
- verbose(env, "pop stack internal bug\n");
- ret = -EFAULT;
- goto err_free;
- }
- goto peek_stack;
- check_state:
- for (i = 0; i < insn_cnt; i++) {
- if (insn_state[i] != EXPLORED) {
- verbose(env, "unreachable insn %d\n", i);
- ret = -EINVAL;
- goto err_free;
- }
- }
- ret = 0; /* cfg looks good */
- err_free:
- kvfree(insn_state);
- kvfree(insn_stack);
- env->cfg.insn_state = env->cfg.insn_stack = NULL;
- return ret;
- }
- static int check_abnormal_return(struct bpf_verifier_env *env)
- {
- int i;
- for (i = 1; i < env->subprog_cnt; i++) {
- if (env->subprog_info[i].has_ld_abs) {
- verbose(env, "LD_ABS is not allowed in subprogs without BTF\n");
- return -EINVAL;
- }
- if (env->subprog_info[i].has_tail_call) {
- verbose(env, "tail_call is not allowed in subprogs without BTF\n");
- return -EINVAL;
- }
- }
- return 0;
- }
- /* The minimum supported BTF func info size */
- #define MIN_BPF_FUNCINFO_SIZE 8
- #define MAX_FUNCINFO_REC_SIZE 252
- static int check_btf_func(struct bpf_verifier_env *env,
- const union bpf_attr *attr,
- union bpf_attr __user *uattr)
- {
- const struct btf_type *type, *func_proto, *ret_type;
- u32 i, nfuncs, urec_size, min_size;
- u32 krec_size = sizeof(struct bpf_func_info);
- struct bpf_func_info *krecord;
- struct bpf_func_info_aux *info_aux = NULL;
- struct bpf_prog *prog;
- const struct btf *btf;
- void __user *urecord;
- u32 prev_offset = 0;
- bool scalar_return;
- int ret = -ENOMEM;
- nfuncs = attr->func_info_cnt;
- if (!nfuncs) {
- if (check_abnormal_return(env))
- return -EINVAL;
- return 0;
- }
- if (nfuncs != env->subprog_cnt) {
- verbose(env, "number of funcs in func_info doesn't match number of subprogs\n");
- return -EINVAL;
- }
- urec_size = attr->func_info_rec_size;
- if (urec_size < MIN_BPF_FUNCINFO_SIZE ||
- urec_size > MAX_FUNCINFO_REC_SIZE ||
- urec_size % sizeof(u32)) {
- verbose(env, "invalid func info rec size %u\n", urec_size);
- return -EINVAL;
- }
- prog = env->prog;
- btf = prog->aux->btf;
- urecord = u64_to_user_ptr(attr->func_info);
- min_size = min_t(u32, krec_size, urec_size);
- krecord = kvcalloc(nfuncs, krec_size, GFP_KERNEL | __GFP_NOWARN);
- if (!krecord)
- return -ENOMEM;
- info_aux = kcalloc(nfuncs, sizeof(*info_aux), GFP_KERNEL | __GFP_NOWARN);
- if (!info_aux)
- goto err_free;
- for (i = 0; i < nfuncs; i++) {
- ret = bpf_check_uarg_tail_zero(urecord, krec_size, urec_size);
- if (ret) {
- if (ret == -E2BIG) {
- verbose(env, "nonzero tailing record in func info");
- /* set the size kernel expects so loader can zero
- * out the rest of the record.
- */
- if (put_user(min_size, &uattr->func_info_rec_size))
- ret = -EFAULT;
- }
- goto err_free;
- }
- if (copy_from_user(&krecord[i], urecord, min_size)) {
- ret = -EFAULT;
- goto err_free;
- }
- /* check insn_off */
- ret = -EINVAL;
- if (i == 0) {
- if (krecord[i].insn_off) {
- verbose(env,
- "nonzero insn_off %u for the first func info record",
- krecord[i].insn_off);
- goto err_free;
- }
- } else if (krecord[i].insn_off <= prev_offset) {
- verbose(env,
- "same or smaller insn offset (%u) than previous func info record (%u)",
- krecord[i].insn_off, prev_offset);
- goto err_free;
- }
- if (env->subprog_info[i].start != krecord[i].insn_off) {
- verbose(env, "func_info BTF section doesn't match subprog layout in BPF program\n");
- goto err_free;
- }
- /* check type_id */
- type = btf_type_by_id(btf, krecord[i].type_id);
- if (!type || !btf_type_is_func(type)) {
- verbose(env, "invalid type id %d in func info",
- krecord[i].type_id);
- goto err_free;
- }
- info_aux[i].linkage = BTF_INFO_VLEN(type->info);
- func_proto = btf_type_by_id(btf, type->type);
- if (unlikely(!func_proto || !btf_type_is_func_proto(func_proto)))
- /* btf_func_check() already verified it during BTF load */
- goto err_free;
- ret_type = btf_type_skip_modifiers(btf, func_proto->type, NULL);
- scalar_return =
- btf_type_is_small_int(ret_type) || btf_type_is_enum(ret_type);
- if (i && !scalar_return && env->subprog_info[i].has_ld_abs) {
- verbose(env, "LD_ABS is only allowed in functions that return 'int'.\n");
- goto err_free;
- }
- if (i && !scalar_return && env->subprog_info[i].has_tail_call) {
- verbose(env, "tail_call is only allowed in functions that return 'int'.\n");
- goto err_free;
- }
- prev_offset = krecord[i].insn_off;
- urecord += urec_size;
- }
- prog->aux->func_info = krecord;
- prog->aux->func_info_cnt = nfuncs;
- prog->aux->func_info_aux = info_aux;
- return 0;
- err_free:
- kvfree(krecord);
- kfree(info_aux);
- return ret;
- }
- static void adjust_btf_func(struct bpf_verifier_env *env)
- {
- struct bpf_prog_aux *aux = env->prog->aux;
- int i;
- if (!aux->func_info)
- return;
- for (i = 0; i < env->subprog_cnt; i++)
- aux->func_info[i].insn_off = env->subprog_info[i].start;
- }
- #define MIN_BPF_LINEINFO_SIZE (offsetof(struct bpf_line_info, line_col) + \
- sizeof(((struct bpf_line_info *)(0))->line_col))
- #define MAX_LINEINFO_REC_SIZE MAX_FUNCINFO_REC_SIZE
- static int check_btf_line(struct bpf_verifier_env *env,
- const union bpf_attr *attr,
- union bpf_attr __user *uattr)
- {
- u32 i, s, nr_linfo, ncopy, expected_size, rec_size, prev_offset = 0;
- struct bpf_subprog_info *sub;
- struct bpf_line_info *linfo;
- struct bpf_prog *prog;
- const struct btf *btf;
- void __user *ulinfo;
- int err;
- nr_linfo = attr->line_info_cnt;
- if (!nr_linfo)
- return 0;
- if (nr_linfo > INT_MAX / sizeof(struct bpf_line_info))
- return -EINVAL;
- rec_size = attr->line_info_rec_size;
- if (rec_size < MIN_BPF_LINEINFO_SIZE ||
- rec_size > MAX_LINEINFO_REC_SIZE ||
- rec_size & (sizeof(u32) - 1))
- return -EINVAL;
- /* Need to zero it in case the userspace may
- * pass in a smaller bpf_line_info object.
- */
- linfo = kvcalloc(nr_linfo, sizeof(struct bpf_line_info),
- GFP_KERNEL | __GFP_NOWARN);
- if (!linfo)
- return -ENOMEM;
- prog = env->prog;
- btf = prog->aux->btf;
- s = 0;
- sub = env->subprog_info;
- ulinfo = u64_to_user_ptr(attr->line_info);
- expected_size = sizeof(struct bpf_line_info);
- ncopy = min_t(u32, expected_size, rec_size);
- for (i = 0; i < nr_linfo; i++) {
- err = bpf_check_uarg_tail_zero(ulinfo, expected_size, rec_size);
- if (err) {
- if (err == -E2BIG) {
- verbose(env, "nonzero tailing record in line_info");
- if (put_user(expected_size,
- &uattr->line_info_rec_size))
- err = -EFAULT;
- }
- goto err_free;
- }
- if (copy_from_user(&linfo[i], ulinfo, ncopy)) {
- err = -EFAULT;
- goto err_free;
- }
- /*
- * Check insn_off to ensure
- * 1) strictly increasing AND
- * 2) bounded by prog->len
- *
- * The linfo[0].insn_off == 0 check logically falls into
- * the later "missing bpf_line_info for func..." case
- * because the first linfo[0].insn_off must be the
- * first sub also and the first sub must have
- * subprog_info[0].start == 0.
- */
- if ((i && linfo[i].insn_off <= prev_offset) ||
- linfo[i].insn_off >= prog->len) {
- verbose(env, "Invalid line_info[%u].insn_off:%u (prev_offset:%u prog->len:%u)\n",
- i, linfo[i].insn_off, prev_offset,
- prog->len);
- err = -EINVAL;
- goto err_free;
- }
- if (!prog->insnsi[linfo[i].insn_off].code) {
- verbose(env,
- "Invalid insn code at line_info[%u].insn_off\n",
- i);
- err = -EINVAL;
- goto err_free;
- }
- if (!btf_name_by_offset(btf, linfo[i].line_off) ||
- !btf_name_by_offset(btf, linfo[i].file_name_off)) {
- verbose(env, "Invalid line_info[%u].line_off or .file_name_off\n", i);
- err = -EINVAL;
- goto err_free;
- }
- if (s != env->subprog_cnt) {
- if (linfo[i].insn_off == sub[s].start) {
- sub[s].linfo_idx = i;
- s++;
- } else if (sub[s].start < linfo[i].insn_off) {
- verbose(env, "missing bpf_line_info for func#%u\n", s);
- err = -EINVAL;
- goto err_free;
- }
- }
- prev_offset = linfo[i].insn_off;
- ulinfo += rec_size;
- }
- if (s != env->subprog_cnt) {
- verbose(env, "missing bpf_line_info for %u funcs starting from func#%u\n",
- env->subprog_cnt - s, s);
- err = -EINVAL;
- goto err_free;
- }
- prog->aux->linfo = linfo;
- prog->aux->nr_linfo = nr_linfo;
- return 0;
- err_free:
- kvfree(linfo);
- return err;
- }
- static int check_btf_info(struct bpf_verifier_env *env,
- const union bpf_attr *attr,
- union bpf_attr __user *uattr)
- {
- struct btf *btf;
- int err;
- if (!attr->func_info_cnt && !attr->line_info_cnt) {
- if (check_abnormal_return(env))
- return -EINVAL;
- return 0;
- }
- btf = btf_get_by_fd(attr->prog_btf_fd);
- if (IS_ERR(btf))
- return PTR_ERR(btf);
- env->prog->aux->btf = btf;
- err = check_btf_func(env, attr, uattr);
- if (err)
- return err;
- err = check_btf_line(env, attr, uattr);
- if (err)
- return err;
- return 0;
- }
- /* check %cur's range satisfies %old's */
- static bool range_within(struct bpf_reg_state *old,
- struct bpf_reg_state *cur)
- {
- return old->umin_value <= cur->umin_value &&
- old->umax_value >= cur->umax_value &&
- old->smin_value <= cur->smin_value &&
- old->smax_value >= cur->smax_value &&
- old->u32_min_value <= cur->u32_min_value &&
- old->u32_max_value >= cur->u32_max_value &&
- old->s32_min_value <= cur->s32_min_value &&
- old->s32_max_value >= cur->s32_max_value;
- }
- /* If in the old state two registers had the same id, then they need to have
- * the same id in the new state as well. But that id could be different from
- * the old state, so we need to track the mapping from old to new ids.
- * Once we have seen that, say, a reg with old id 5 had new id 9, any subsequent
- * regs with old id 5 must also have new id 9 for the new state to be safe. But
- * regs with a different old id could still have new id 9, we don't care about
- * that.
- * So we look through our idmap to see if this old id has been seen before. If
- * so, we require the new id to match; otherwise, we add the id pair to the map.
- */
- static bool check_ids(u32 old_id, u32 cur_id, struct bpf_id_pair *idmap)
- {
- unsigned int i;
- for (i = 0; i < BPF_ID_MAP_SIZE; i++) {
- if (!idmap[i].old) {
- /* Reached an empty slot; haven't seen this id before */
- idmap[i].old = old_id;
- idmap[i].cur = cur_id;
- return true;
- }
- if (idmap[i].old == old_id)
- return idmap[i].cur == cur_id;
- }
- /* We ran out of idmap slots, which should be impossible */
- WARN_ON_ONCE(1);
- return false;
- }
- static void clean_func_state(struct bpf_verifier_env *env,
- struct bpf_func_state *st)
- {
- enum bpf_reg_liveness live;
- int i, j;
- for (i = 0; i < BPF_REG_FP; i++) {
- live = st->regs[i].live;
- /* liveness must not touch this register anymore */
- st->regs[i].live |= REG_LIVE_DONE;
- if (!(live & REG_LIVE_READ))
- /* since the register is unused, clear its state
- * to make further comparison simpler
- */
- __mark_reg_not_init(env, &st->regs[i]);
- }
- for (i = 0; i < st->allocated_stack / BPF_REG_SIZE; i++) {
- live = st->stack[i].spilled_ptr.live;
- /* liveness must not touch this stack slot anymore */
- st->stack[i].spilled_ptr.live |= REG_LIVE_DONE;
- if (!(live & REG_LIVE_READ)) {
- __mark_reg_not_init(env, &st->stack[i].spilled_ptr);
- for (j = 0; j < BPF_REG_SIZE; j++)
- st->stack[i].slot_type[j] = STACK_INVALID;
- }
- }
- }
- static void clean_verifier_state(struct bpf_verifier_env *env,
- struct bpf_verifier_state *st)
- {
- int i;
- if (st->frame[0]->regs[0].live & REG_LIVE_DONE)
- /* all regs in this state in all frames were already marked */
- return;
- for (i = 0; i <= st->curframe; i++)
- clean_func_state(env, st->frame[i]);
- }
- /* the parentage chains form a tree.
- * the verifier states are added to state lists at given insn and
- * pushed into state stack for future exploration.
- * when the verifier reaches bpf_exit insn some of the verifer states
- * stored in the state lists have their final liveness state already,
- * but a lot of states will get revised from liveness point of view when
- * the verifier explores other branches.
- * Example:
- * 1: r0 = 1
- * 2: if r1 == 100 goto pc+1
- * 3: r0 = 2
- * 4: exit
- * when the verifier reaches exit insn the register r0 in the state list of
- * insn 2 will be seen as !REG_LIVE_READ. Then the verifier pops the other_branch
- * of insn 2 and goes exploring further. At the insn 4 it will walk the
- * parentage chain from insn 4 into insn 2 and will mark r0 as REG_LIVE_READ.
- *
- * Since the verifier pushes the branch states as it sees them while exploring
- * the program the condition of walking the branch instruction for the second
- * time means that all states below this branch were already explored and
- * their final liveness markes are already propagated.
- * Hence when the verifier completes the search of state list in is_state_visited()
- * we can call this clean_live_states() function to mark all liveness states
- * as REG_LIVE_DONE to indicate that 'parent' pointers of 'struct bpf_reg_state'
- * will not be used.
- * This function also clears the registers and stack for states that !READ
- * to simplify state merging.
- *
- * Important note here that walking the same branch instruction in the callee
- * doesn't meant that the states are DONE. The verifier has to compare
- * the callsites
- */
- static void clean_live_states(struct bpf_verifier_env *env, int insn,
- struct bpf_verifier_state *cur)
- {
- struct bpf_verifier_state_list *sl;
- int i;
- sl = *explored_state(env, insn);
- while (sl) {
- if (sl->state.branches)
- goto next;
- if (sl->state.insn_idx != insn ||
- sl->state.curframe != cur->curframe)
- goto next;
- for (i = 0; i <= cur->curframe; i++)
- if (sl->state.frame[i]->callsite != cur->frame[i]->callsite)
- goto next;
- clean_verifier_state(env, &sl->state);
- next:
- sl = sl->next;
- }
- }
- /* Returns true if (rold safe implies rcur safe) */
- static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold,
- struct bpf_reg_state *rcur, struct bpf_id_pair *idmap)
- {
- bool equal;
- if (!(rold->live & REG_LIVE_READ))
- /* explored state didn't use this */
- return true;
- equal = memcmp(rold, rcur, offsetof(struct bpf_reg_state, parent)) == 0;
- if (rold->type == PTR_TO_STACK)
- /* two stack pointers are equal only if they're pointing to
- * the same stack frame, since fp-8 in foo != fp-8 in bar
- */
- return equal && rold->frameno == rcur->frameno;
- if (equal)
- return true;
- if (rold->type == NOT_INIT)
- /* explored state can't have used this */
- return true;
- if (rcur->type == NOT_INIT)
- return false;
- switch (rold->type) {
- case SCALAR_VALUE:
- if (env->explore_alu_limits)
- return false;
- if (rcur->type == SCALAR_VALUE) {
- if (!rold->precise && !rcur->precise)
- return true;
- /* new val must satisfy old val knowledge */
- return range_within(rold, rcur) &&
- tnum_in(rold->var_off, rcur->var_off);
- } else {
- /* We're trying to use a pointer in place of a scalar.
- * Even if the scalar was unbounded, this could lead to
- * pointer leaks because scalars are allowed to leak
- * while pointers are not. We could make this safe in
- * special cases if root is calling us, but it's
- * probably not worth the hassle.
- */
- return false;
- }
- case PTR_TO_MAP_VALUE:
- /* If the new min/max/var_off satisfy the old ones and
- * everything else matches, we are OK.
- * 'id' is not compared, since it's only used for maps with
- * bpf_spin_lock inside map element and in such cases if
- * the rest of the prog is valid for one map element then
- * it's valid for all map elements regardless of the key
- * used in bpf_map_lookup()
- */
- return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 &&
- range_within(rold, rcur) &&
- tnum_in(rold->var_off, rcur->var_off);
- case PTR_TO_MAP_VALUE_OR_NULL:
- /* a PTR_TO_MAP_VALUE could be safe to use as a
- * PTR_TO_MAP_VALUE_OR_NULL into the same map.
- * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL-
- * checked, doing so could have affected others with the same
- * id, and we can't check for that because we lost the id when
- * we converted to a PTR_TO_MAP_VALUE.
- */
- if (rcur->type != PTR_TO_MAP_VALUE_OR_NULL)
- return false;
- if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)))
- return false;
- /* Check our ids match any regs they're supposed to */
- return check_ids(rold->id, rcur->id, idmap);
- case PTR_TO_PACKET_META:
- case PTR_TO_PACKET:
- if (rcur->type != rold->type)
- return false;
- /* We must have at least as much range as the old ptr
- * did, so that any accesses which were safe before are
- * still safe. This is true even if old range < old off,
- * since someone could have accessed through (ptr - k), or
- * even done ptr -= k in a register, to get a safe access.
- */
- if (rold->range > rcur->range)
- return false;
- /* If the offsets don't match, we can't trust our alignment;
- * nor can we be sure that we won't fall out of range.
- */
- if (rold->off != rcur->off)
- return false;
- /* id relations must be preserved */
- if (rold->id && !check_ids(rold->id, rcur->id, idmap))
- return false;
- /* new val must satisfy old val knowledge */
- return range_within(rold, rcur) &&
- tnum_in(rold->var_off, rcur->var_off);
- case PTR_TO_CTX:
- case CONST_PTR_TO_MAP:
- case PTR_TO_PACKET_END:
- case PTR_TO_FLOW_KEYS:
- case PTR_TO_SOCKET:
- case PTR_TO_SOCKET_OR_NULL:
- case PTR_TO_SOCK_COMMON:
- case PTR_TO_SOCK_COMMON_OR_NULL:
- case PTR_TO_TCP_SOCK:
- case PTR_TO_TCP_SOCK_OR_NULL:
- case PTR_TO_XDP_SOCK:
- /* Only valid matches are exact, which memcmp() above
- * would have accepted
- */
- default:
- /* Don't know what's going on, just say it's not safe */
- return false;
- }
- /* Shouldn't get here; if we do, say it's not safe */
- WARN_ON_ONCE(1);
- return false;
- }
- static bool stacksafe(struct bpf_verifier_env *env, struct bpf_func_state *old,
- struct bpf_func_state *cur, struct bpf_id_pair *idmap)
- {
- int i, spi;
- /* walk slots of the explored stack and ignore any additional
- * slots in the current stack, since explored(safe) state
- * didn't use them
- */
- for (i = 0; i < old->allocated_stack; i++) {
- spi = i / BPF_REG_SIZE;
- if (!(old->stack[spi].spilled_ptr.live & REG_LIVE_READ)) {
- i += BPF_REG_SIZE - 1;
- /* explored state didn't use this */
- continue;
- }
- if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_INVALID)
- continue;
- /* explored stack has more populated slots than current stack
- * and these slots were used
- */
- if (i >= cur->allocated_stack)
- return false;
- /* if old state was safe with misc data in the stack
- * it will be safe with zero-initialized stack.
- * The opposite is not true
- */
- if (old->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_MISC &&
- cur->stack[spi].slot_type[i % BPF_REG_SIZE] == STACK_ZERO)
- continue;
- if (old->stack[spi].slot_type[i % BPF_REG_SIZE] !=
- cur->stack[spi].slot_type[i % BPF_REG_SIZE])
- /* Ex: old explored (safe) state has STACK_SPILL in
- * this stack slot, but current has STACK_MISC ->
- * this verifier states are not equivalent,
- * return false to continue verification of this path
- */
- return false;
- if (i % BPF_REG_SIZE)
- continue;
- if (old->stack[spi].slot_type[0] != STACK_SPILL)
- continue;
- if (!regsafe(env, &old->stack[spi].spilled_ptr,
- &cur->stack[spi].spilled_ptr, idmap))
- /* when explored and current stack slot are both storing
- * spilled registers, check that stored pointers types
- * are the same as well.
- * Ex: explored safe path could have stored
- * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -8}
- * but current path has stored:
- * (bpf_reg_state) {.type = PTR_TO_STACK, .off = -16}
- * such verifier states are not equivalent.
- * return false to continue verification of this path
- */
- return false;
- }
- return true;
- }
- static bool refsafe(struct bpf_func_state *old, struct bpf_func_state *cur)
- {
- if (old->acquired_refs != cur->acquired_refs)
- return false;
- return !memcmp(old->refs, cur->refs,
- sizeof(*old->refs) * old->acquired_refs);
- }
- /* compare two verifier states
- *
- * all states stored in state_list are known to be valid, since
- * verifier reached 'bpf_exit' instruction through them
- *
- * this function is called when verifier exploring different branches of
- * execution popped from the state stack. If it sees an old state that has
- * more strict register state and more strict stack state then this execution
- * branch doesn't need to be explored further, since verifier already
- * concluded that more strict state leads to valid finish.
- *
- * Therefore two states are equivalent if register state is more conservative
- * and explored stack state is more conservative than the current one.
- * Example:
- * explored current
- * (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
- * (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
- *
- * In other words if current stack state (one being explored) has more
- * valid slots than old one that already passed validation, it means
- * the verifier can stop exploring and conclude that current state is valid too
- *
- * Similarly with registers. If explored state has register type as invalid
- * whereas register type in current state is meaningful, it means that
- * the current state will reach 'bpf_exit' instruction safely
- */
- static bool func_states_equal(struct bpf_verifier_env *env, struct bpf_func_state *old,
- struct bpf_func_state *cur)
- {
- int i;
- memset(env->idmap_scratch, 0, sizeof(env->idmap_scratch));
- for (i = 0; i < MAX_BPF_REG; i++)
- if (!regsafe(env, &old->regs[i], &cur->regs[i],
- env->idmap_scratch))
- return false;
- if (!stacksafe(env, old, cur, env->idmap_scratch))
- return false;
- if (!refsafe(old, cur))
- return false;
- return true;
- }
- static bool states_equal(struct bpf_verifier_env *env,
- struct bpf_verifier_state *old,
- struct bpf_verifier_state *cur)
- {
- int i;
- if (old->curframe != cur->curframe)
- return false;
- /* Verification state from speculative execution simulation
- * must never prune a non-speculative execution one.
- */
- if (old->speculative && !cur->speculative)
- return false;
- if (old->active_spin_lock != cur->active_spin_lock)
- return false;
- /* for states to be equal callsites have to be the same
- * and all frame states need to be equivalent
- */
- for (i = 0; i <= old->curframe; i++) {
- if (old->frame[i]->callsite != cur->frame[i]->callsite)
- return false;
- if (!func_states_equal(env, old->frame[i], cur->frame[i]))
- return false;
- }
- return true;
- }
- /* Return 0 if no propagation happened. Return negative error code if error
- * happened. Otherwise, return the propagated bit.
- */
- static int propagate_liveness_reg(struct bpf_verifier_env *env,
- struct bpf_reg_state *reg,
- struct bpf_reg_state *parent_reg)
- {
- u8 parent_flag = parent_reg->live & REG_LIVE_READ;
- u8 flag = reg->live & REG_LIVE_READ;
- int err;
- /* When comes here, read flags of PARENT_REG or REG could be any of
- * REG_LIVE_READ64, REG_LIVE_READ32, REG_LIVE_NONE. There is no need
- * of propagation if PARENT_REG has strongest REG_LIVE_READ64.
- */
- if (parent_flag == REG_LIVE_READ64 ||
- /* Or if there is no read flag from REG. */
- !flag ||
- /* Or if the read flag from REG is the same as PARENT_REG. */
- parent_flag == flag)
- return 0;
- err = mark_reg_read(env, reg, parent_reg, flag);
- if (err)
- return err;
- return flag;
- }
- /* A write screens off any subsequent reads; but write marks come from the
- * straight-line code between a state and its parent. When we arrive at an
- * equivalent state (jump target or such) we didn't arrive by the straight-line
- * code, so read marks in the state must propagate to the parent regardless
- * of the state's write marks. That's what 'parent == state->parent' comparison
- * in mark_reg_read() is for.
- */
- static int propagate_liveness(struct bpf_verifier_env *env,
- const struct bpf_verifier_state *vstate,
- struct bpf_verifier_state *vparent)
- {
- struct bpf_reg_state *state_reg, *parent_reg;
- struct bpf_func_state *state, *parent;
- int i, frame, err = 0;
- if (vparent->curframe != vstate->curframe) {
- WARN(1, "propagate_live: parent frame %d current frame %d\n",
- vparent->curframe, vstate->curframe);
- return -EFAULT;
- }
- /* Propagate read liveness of registers... */
- BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG);
- for (frame = 0; frame <= vstate->curframe; frame++) {
- parent = vparent->frame[frame];
- state = vstate->frame[frame];
- parent_reg = parent->regs;
- state_reg = state->regs;
- /* We don't need to worry about FP liveness, it's read-only */
- for (i = frame < vstate->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++) {
- err = propagate_liveness_reg(env, &state_reg[i],
- &parent_reg[i]);
- if (err < 0)
- return err;
- if (err == REG_LIVE_READ64)
- mark_insn_zext(env, &parent_reg[i]);
- }
- /* Propagate stack slots. */
- for (i = 0; i < state->allocated_stack / BPF_REG_SIZE &&
- i < parent->allocated_stack / BPF_REG_SIZE; i++) {
- parent_reg = &parent->stack[i].spilled_ptr;
- state_reg = &state->stack[i].spilled_ptr;
- err = propagate_liveness_reg(env, state_reg,
- parent_reg);
- if (err < 0)
- return err;
- }
- }
- return 0;
- }
- /* find precise scalars in the previous equivalent state and
- * propagate them into the current state
- */
- static int propagate_precision(struct bpf_verifier_env *env,
- const struct bpf_verifier_state *old)
- {
- struct bpf_reg_state *state_reg;
- struct bpf_func_state *state;
- int i, err = 0;
- state = old->frame[old->curframe];
- state_reg = state->regs;
- for (i = 0; i < BPF_REG_FP; i++, state_reg++) {
- if (state_reg->type != SCALAR_VALUE ||
- !state_reg->precise)
- continue;
- if (env->log.level & BPF_LOG_LEVEL2)
- verbose(env, "propagating r%d\n", i);
- err = mark_chain_precision(env, i);
- if (err < 0)
- return err;
- }
- for (i = 0; i < state->allocated_stack / BPF_REG_SIZE; i++) {
- if (state->stack[i].slot_type[0] != STACK_SPILL)
- continue;
- state_reg = &state->stack[i].spilled_ptr;
- if (state_reg->type != SCALAR_VALUE ||
- !state_reg->precise)
- continue;
- if (env->log.level & BPF_LOG_LEVEL2)
- verbose(env, "propagating fp%d\n",
- (-i - 1) * BPF_REG_SIZE);
- err = mark_chain_precision_stack(env, i);
- if (err < 0)
- return err;
- }
- return 0;
- }
- static bool states_maybe_looping(struct bpf_verifier_state *old,
- struct bpf_verifier_state *cur)
- {
- struct bpf_func_state *fold, *fcur;
- int i, fr = cur->curframe;
- if (old->curframe != fr)
- return false;
- fold = old->frame[fr];
- fcur = cur->frame[fr];
- for (i = 0; i < MAX_BPF_REG; i++)
- if (memcmp(&fold->regs[i], &fcur->regs[i],
- offsetof(struct bpf_reg_state, parent)))
- return false;
- return true;
- }
- static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
- {
- struct bpf_verifier_state_list *new_sl;
- struct bpf_verifier_state_list *sl, **pprev;
- struct bpf_verifier_state *cur = env->cur_state, *new;
- int i, j, err, states_cnt = 0;
- bool add_new_state = env->test_state_freq ? true : false;
- cur->last_insn_idx = env->prev_insn_idx;
- if (!env->insn_aux_data[insn_idx].prune_point)
- /* this 'insn_idx' instruction wasn't marked, so we will not
- * be doing state search here
- */
- return 0;
- /* bpf progs typically have pruning point every 4 instructions
- * http://vger.kernel.org/bpfconf2019.html#session-1
- * Do not add new state for future pruning if the verifier hasn't seen
- * at least 2 jumps and at least 8 instructions.
- * This heuristics helps decrease 'total_states' and 'peak_states' metric.
- * In tests that amounts to up to 50% reduction into total verifier
- * memory consumption and 20% verifier time speedup.
- */
- if (env->jmps_processed - env->prev_jmps_processed >= 2 &&
- env->insn_processed - env->prev_insn_processed >= 8)
- add_new_state = true;
- pprev = explored_state(env, insn_idx);
- sl = *pprev;
- clean_live_states(env, insn_idx, cur);
- while (sl) {
- states_cnt++;
- if (sl->state.insn_idx != insn_idx)
- goto next;
- if (sl->state.branches) {
- if (states_maybe_looping(&sl->state, cur) &&
- states_equal(env, &sl->state, cur)) {
- verbose_linfo(env, insn_idx, "; ");
- verbose(env, "infinite loop detected at insn %d\n", insn_idx);
- return -EINVAL;
- }
- /* if the verifier is processing a loop, avoid adding new state
- * too often, since different loop iterations have distinct
- * states and may not help future pruning.
- * This threshold shouldn't be too low to make sure that
- * a loop with large bound will be rejected quickly.
- * The most abusive loop will be:
- * r1 += 1
- * if r1 < 1000000 goto pc-2
- * 1M insn_procssed limit / 100 == 10k peak states.
- * This threshold shouldn't be too high either, since states
- * at the end of the loop are likely to be useful in pruning.
- */
- if (env->jmps_processed - env->prev_jmps_processed < 20 &&
- env->insn_processed - env->prev_insn_processed < 100)
- add_new_state = false;
- goto miss;
- }
- if (states_equal(env, &sl->state, cur)) {
- sl->hit_cnt++;
- /* reached equivalent register/stack state,
- * prune the search.
- * Registers read by the continuation are read by us.
- * If we have any write marks in env->cur_state, they
- * will prevent corresponding reads in the continuation
- * from reaching our parent (an explored_state). Our
- * own state will get the read marks recorded, but
- * they'll be immediately forgotten as we're pruning
- * this state and will pop a new one.
- */
- err = propagate_liveness(env, &sl->state, cur);
- /* if previous state reached the exit with precision and
- * current state is equivalent to it (except precsion marks)
- * the precision needs to be propagated back in
- * the current state.
- */
- err = err ? : push_jmp_history(env, cur);
- err = err ? : propagate_precision(env, &sl->state);
- if (err)
- return err;
- return 1;
- }
- miss:
- /* when new state is not going to be added do not increase miss count.
- * Otherwise several loop iterations will remove the state
- * recorded earlier. The goal of these heuristics is to have
- * states from some iterations of the loop (some in the beginning
- * and some at the end) to help pruning.
- */
- if (add_new_state)
- sl->miss_cnt++;
- /* heuristic to determine whether this state is beneficial
- * to keep checking from state equivalence point of view.
- * Higher numbers increase max_states_per_insn and verification time,
- * but do not meaningfully decrease insn_processed.
- */
- if (sl->miss_cnt > sl->hit_cnt * 3 + 3) {
- /* the state is unlikely to be useful. Remove it to
- * speed up verification
- */
- *pprev = sl->next;
- if (sl->state.frame[0]->regs[0].live & REG_LIVE_DONE) {
- u32 br = sl->state.branches;
- WARN_ONCE(br,
- "BUG live_done but branches_to_explore %d\n",
- br);
- free_verifier_state(&sl->state, false);
- kfree(sl);
- env->peak_states--;
- } else {
- /* cannot free this state, since parentage chain may
- * walk it later. Add it for free_list instead to
- * be freed at the end of verification
- */
- sl->next = env->free_list;
- env->free_list = sl;
- }
- sl = *pprev;
- continue;
- }
- next:
- pprev = &sl->next;
- sl = *pprev;
- }
- if (env->max_states_per_insn < states_cnt)
- env->max_states_per_insn = states_cnt;
- if (!env->bpf_capable && states_cnt > BPF_COMPLEXITY_LIMIT_STATES)
- return push_jmp_history(env, cur);
- if (!add_new_state)
- return push_jmp_history(env, cur);
- /* There were no equivalent states, remember the current one.
- * Technically the current state is not proven to be safe yet,
- * but it will either reach outer most bpf_exit (which means it's safe)
- * or it will be rejected. When there are no loops the verifier won't be
- * seeing this tuple (frame[0].callsite, frame[1].callsite, .. insn_idx)
- * again on the way to bpf_exit.
- * When looping the sl->state.branches will be > 0 and this state
- * will not be considered for equivalence until branches == 0.
- */
- new_sl = kzalloc(sizeof(struct bpf_verifier_state_list), GFP_KERNEL);
- if (!new_sl)
- return -ENOMEM;
- env->total_states++;
- env->peak_states++;
- env->prev_jmps_processed = env->jmps_processed;
- env->prev_insn_processed = env->insn_processed;
- /* add new state to the head of linked list */
- new = &new_sl->state;
- err = copy_verifier_state(new, cur);
- if (err) {
- free_verifier_state(new, false);
- kfree(new_sl);
- return err;
- }
- new->insn_idx = insn_idx;
- WARN_ONCE(new->branches != 1,
- "BUG is_state_visited:branches_to_explore=%d insn %d\n", new->branches, insn_idx);
- cur->parent = new;
- cur->first_insn_idx = insn_idx;
- clear_jmp_history(cur);
- new_sl->next = *explored_state(env, insn_idx);
- *explored_state(env, insn_idx) = new_sl;
- /* connect new state to parentage chain. Current frame needs all
- * registers connected. Only r6 - r9 of the callers are alive (pushed
- * to the stack implicitly by JITs) so in callers' frames connect just
- * r6 - r9 as an optimization. Callers will have r1 - r5 connected to
- * the state of the call instruction (with WRITTEN set), and r0 comes
- * from callee with its full parentage chain, anyway.
- */
- /* clear write marks in current state: the writes we did are not writes
- * our child did, so they don't screen off its reads from us.
- * (There are no read marks in current state, because reads always mark
- * their parent and current state never has children yet. Only
- * explored_states can get read marks.)
- */
- for (j = 0; j <= cur->curframe; j++) {
- for (i = j < cur->curframe ? BPF_REG_6 : 0; i < BPF_REG_FP; i++)
- cur->frame[j]->regs[i].parent = &new->frame[j]->regs[i];
- for (i = 0; i < BPF_REG_FP; i++)
- cur->frame[j]->regs[i].live = REG_LIVE_NONE;
- }
- /* all stack frames are accessible from callee, clear them all */
- for (j = 0; j <= cur->curframe; j++) {
- struct bpf_func_state *frame = cur->frame[j];
- struct bpf_func_state *newframe = new->frame[j];
- for (i = 0; i < frame->allocated_stack / BPF_REG_SIZE; i++) {
- frame->stack[i].spilled_ptr.live = REG_LIVE_NONE;
- frame->stack[i].spilled_ptr.parent =
- &newframe->stack[i].spilled_ptr;
- }
- }
- return 0;
- }
- /* Return true if it's OK to have the same insn return a different type. */
- static bool reg_type_mismatch_ok(enum bpf_reg_type type)
- {
- switch (type) {
- case PTR_TO_CTX:
- case PTR_TO_SOCKET:
- case PTR_TO_SOCKET_OR_NULL:
- case PTR_TO_SOCK_COMMON:
- case PTR_TO_SOCK_COMMON_OR_NULL:
- case PTR_TO_TCP_SOCK:
- case PTR_TO_TCP_SOCK_OR_NULL:
- case PTR_TO_XDP_SOCK:
- case PTR_TO_BTF_ID:
- case PTR_TO_BTF_ID_OR_NULL:
- return false;
- default:
- return true;
- }
- }
- /* If an instruction was previously used with particular pointer types, then we
- * need to be careful to avoid cases such as the below, where it may be ok
- * for one branch accessing the pointer, but not ok for the other branch:
- *
- * R1 = sock_ptr
- * goto X;
- * ...
- * R1 = some_other_valid_ptr;
- * goto X;
- * ...
- * R2 = *(u32 *)(R1 + 0);
- */
- static bool reg_type_mismatch(enum bpf_reg_type src, enum bpf_reg_type prev)
- {
- return src != prev && (!reg_type_mismatch_ok(src) ||
- !reg_type_mismatch_ok(prev));
- }
- static int do_check(struct bpf_verifier_env *env)
- {
- bool pop_log = !(env->log.level & BPF_LOG_LEVEL2);
- struct bpf_verifier_state *state = env->cur_state;
- struct bpf_insn *insns = env->prog->insnsi;
- struct bpf_reg_state *regs;
- int insn_cnt = env->prog->len;
- bool do_print_state = false;
- int prev_insn_idx = -1;
- for (;;) {
- struct bpf_insn *insn;
- u8 class;
- int err;
- env->prev_insn_idx = prev_insn_idx;
- if (env->insn_idx >= insn_cnt) {
- verbose(env, "invalid insn idx %d insn_cnt %d\n",
- env->insn_idx, insn_cnt);
- return -EFAULT;
- }
- insn = &insns[env->insn_idx];
- class = BPF_CLASS(insn->code);
- if (++env->insn_processed > BPF_COMPLEXITY_LIMIT_INSNS) {
- verbose(env,
- "BPF program is too large. Processed %d insn\n",
- env->insn_processed);
- return -E2BIG;
- }
- err = is_state_visited(env, env->insn_idx);
- if (err < 0)
- return err;
- if (err == 1) {
- /* found equivalent state, can prune the search */
- if (env->log.level & BPF_LOG_LEVEL) {
- if (do_print_state)
- verbose(env, "\nfrom %d to %d%s: safe\n",
- env->prev_insn_idx, env->insn_idx,
- env->cur_state->speculative ?
- " (speculative execution)" : "");
- else
- verbose(env, "%d: safe\n", env->insn_idx);
- }
- goto process_bpf_exit;
- }
- if (signal_pending(current))
- return -EAGAIN;
- if (need_resched())
- cond_resched();
- if (env->log.level & BPF_LOG_LEVEL2 ||
- (env->log.level & BPF_LOG_LEVEL && do_print_state)) {
- if (env->log.level & BPF_LOG_LEVEL2)
- verbose(env, "%d:", env->insn_idx);
- else
- verbose(env, "\nfrom %d to %d%s:",
- env->prev_insn_idx, env->insn_idx,
- env->cur_state->speculative ?
- " (speculative execution)" : "");
- print_verifier_state(env, state->frame[state->curframe]);
- do_print_state = false;
- }
- if (env->log.level & BPF_LOG_LEVEL) {
- const struct bpf_insn_cbs cbs = {
- .cb_print = verbose,
- .private_data = env,
- };
- verbose_linfo(env, env->insn_idx, "; ");
- verbose(env, "%d: ", env->insn_idx);
- print_bpf_insn(&cbs, insn, env->allow_ptr_leaks);
- }
- if (bpf_prog_is_dev_bound(env->prog->aux)) {
- err = bpf_prog_offload_verify_insn(env, env->insn_idx,
- env->prev_insn_idx);
- if (err)
- return err;
- }
- regs = cur_regs(env);
- sanitize_mark_insn_seen(env);
- prev_insn_idx = env->insn_idx;
- if (class == BPF_ALU || class == BPF_ALU64) {
- err = check_alu_op(env, insn);
- if (err)
- return err;
- } else if (class == BPF_LDX) {
- enum bpf_reg_type *prev_src_type, src_reg_type;
- /* check for reserved fields is already done */
- /* check src operand */
- err = check_reg_arg(env, insn->src_reg, SRC_OP);
- if (err)
- return err;
- err = check_reg_arg(env, insn->dst_reg, DST_OP_NO_MARK);
- if (err)
- return err;
- src_reg_type = regs[insn->src_reg].type;
- /* check that memory (src_reg + off) is readable,
- * the state of dst_reg will be updated by this func
- */
- err = check_mem_access(env, env->insn_idx, insn->src_reg,
- insn->off, BPF_SIZE(insn->code),
- BPF_READ, insn->dst_reg, false);
- if (err)
- return err;
- prev_src_type = &env->insn_aux_data[env->insn_idx].ptr_type;
- if (*prev_src_type == NOT_INIT) {
- /* saw a valid insn
- * dst_reg = *(u32 *)(src_reg + off)
- * save type to validate intersecting paths
- */
- *prev_src_type = src_reg_type;
- } else if (reg_type_mismatch(src_reg_type, *prev_src_type)) {
- /* ABuser program is trying to use the same insn
- * dst_reg = *(u32*) (src_reg + off)
- * with different pointer types:
- * src_reg == ctx in one branch and
- * src_reg == stack|map in some other branch.
- * Reject it.
- */
- verbose(env, "same insn cannot be used with different pointers\n");
- return -EINVAL;
- }
- } else if (class == BPF_STX) {
- enum bpf_reg_type *prev_dst_type, dst_reg_type;
- if (BPF_MODE(insn->code) == BPF_XADD) {
- err = check_xadd(env, env->insn_idx, insn);
- if (err)
- return err;
- env->insn_idx++;
- continue;
- }
- /* check src1 operand */
- err = check_reg_arg(env, insn->src_reg, SRC_OP);
- if (err)
- return err;
- /* check src2 operand */
- err = check_reg_arg(env, insn->dst_reg, SRC_OP);
- if (err)
- return err;
- dst_reg_type = regs[insn->dst_reg].type;
- /* check that memory (dst_reg + off) is writeable */
- err = check_mem_access(env, env->insn_idx, insn->dst_reg,
- insn->off, BPF_SIZE(insn->code),
- BPF_WRITE, insn->src_reg, false);
- if (err)
- return err;
- prev_dst_type = &env->insn_aux_data[env->insn_idx].ptr_type;
- if (*prev_dst_type == NOT_INIT) {
- *prev_dst_type = dst_reg_type;
- } else if (reg_type_mismatch(dst_reg_type, *prev_dst_type)) {
- verbose(env, "same insn cannot be used with different pointers\n");
- return -EINVAL;
- }
- } else if (class == BPF_ST) {
- if (BPF_MODE(insn->code) != BPF_MEM ||
- insn->src_reg != BPF_REG_0) {
- verbose(env, "BPF_ST uses reserved fields\n");
- return -EINVAL;
- }
- /* check src operand */
- err = check_reg_arg(env, insn->dst_reg, SRC_OP);
- if (err)
- return err;
- if (is_ctx_reg(env, insn->dst_reg)) {
- verbose(env, "BPF_ST stores into R%d %s is not allowed\n",
- insn->dst_reg,
- reg_type_str[reg_state(env, insn->dst_reg)->type]);
- return -EACCES;
- }
- /* check that memory (dst_reg + off) is writeable */
- err = check_mem_access(env, env->insn_idx, insn->dst_reg,
- insn->off, BPF_SIZE(insn->code),
- BPF_WRITE, -1, false);
- if (err)
- return err;
- } else if (class == BPF_JMP || class == BPF_JMP32) {
- u8 opcode = BPF_OP(insn->code);
- env->jmps_processed++;
- if (opcode == BPF_CALL) {
- if (BPF_SRC(insn->code) != BPF_K ||
- insn->off != 0 ||
- (insn->src_reg != BPF_REG_0 &&
- insn->src_reg != BPF_PSEUDO_CALL) ||
- insn->dst_reg != BPF_REG_0 ||
- class == BPF_JMP32) {
- verbose(env, "BPF_CALL uses reserved fields\n");
- return -EINVAL;
- }
- if (env->cur_state->active_spin_lock &&
- (insn->src_reg == BPF_PSEUDO_CALL ||
- insn->imm != BPF_FUNC_spin_unlock)) {
- verbose(env, "function calls are not allowed while holding a lock\n");
- return -EINVAL;
- }
- if (insn->src_reg == BPF_PSEUDO_CALL)
- err = check_func_call(env, insn, &env->insn_idx);
- else
- err = check_helper_call(env, insn->imm, env->insn_idx);
- if (err)
- return err;
- } else if (opcode == BPF_JA) {
- if (BPF_SRC(insn->code) != BPF_K ||
- insn->imm != 0 ||
- insn->src_reg != BPF_REG_0 ||
- insn->dst_reg != BPF_REG_0 ||
- class == BPF_JMP32) {
- verbose(env, "BPF_JA uses reserved fields\n");
- return -EINVAL;
- }
- env->insn_idx += insn->off + 1;
- continue;
- } else if (opcode == BPF_EXIT) {
- if (BPF_SRC(insn->code) != BPF_K ||
- insn->imm != 0 ||
- insn->src_reg != BPF_REG_0 ||
- insn->dst_reg != BPF_REG_0 ||
- class == BPF_JMP32) {
- verbose(env, "BPF_EXIT uses reserved fields\n");
- return -EINVAL;
- }
- if (env->cur_state->active_spin_lock) {
- verbose(env, "bpf_spin_unlock is missing\n");
- return -EINVAL;
- }
- if (state->curframe) {
- /* exit from nested function */
- err = prepare_func_exit(env, &env->insn_idx);
- if (err)
- return err;
- do_print_state = true;
- continue;
- }
- err = check_reference_leak(env);
- if (err)
- return err;
- err = check_return_code(env);
- if (err)
- return err;
- process_bpf_exit:
- update_branch_counts(env, env->cur_state);
- err = pop_stack(env, &prev_insn_idx,
- &env->insn_idx, pop_log);
- if (err < 0) {
- if (err != -ENOENT)
- return err;
- break;
- } else {
- do_print_state = true;
- continue;
- }
- } else {
- err = check_cond_jmp_op(env, insn, &env->insn_idx);
- if (err)
- return err;
- }
- } else if (class == BPF_LD) {
- u8 mode = BPF_MODE(insn->code);
- if (mode == BPF_ABS || mode == BPF_IND) {
- err = check_ld_abs(env, insn);
- if (err)
- return err;
- } else if (mode == BPF_IMM) {
- err = check_ld_imm(env, insn);
- if (err)
- return err;
- env->insn_idx++;
- sanitize_mark_insn_seen(env);
- } else {
- verbose(env, "invalid BPF_LD mode\n");
- return -EINVAL;
- }
- } else {
- verbose(env, "unknown insn class %d\n", class);
- return -EINVAL;
- }
- env->insn_idx++;
- }
- return 0;
- }
- /* replace pseudo btf_id with kernel symbol address */
- static int check_pseudo_btf_id(struct bpf_verifier_env *env,
- struct bpf_insn *insn,
- struct bpf_insn_aux_data *aux)
- {
- const struct btf_var_secinfo *vsi;
- const struct btf_type *datasec;
- const struct btf_type *t;
- const char *sym_name;
- bool percpu = false;
- u32 type, id = insn->imm;
- s32 datasec_id;
- u64 addr;
- int i;
- if (!btf_vmlinux) {
- verbose(env, "kernel is missing BTF, make sure CONFIG_DEBUG_INFO_BTF=y is specified in Kconfig.\n");
- return -EINVAL;
- }
- if (insn[1].imm != 0) {
- verbose(env, "reserved field (insn[1].imm) is used in pseudo_btf_id ldimm64 insn.\n");
- return -EINVAL;
- }
- t = btf_type_by_id(btf_vmlinux, id);
- if (!t) {
- verbose(env, "ldimm64 insn specifies invalid btf_id %d.\n", id);
- return -ENOENT;
- }
- if (!btf_type_is_var(t)) {
- verbose(env, "pseudo btf_id %d in ldimm64 isn't KIND_VAR.\n",
- id);
- return -EINVAL;
- }
- sym_name = btf_name_by_offset(btf_vmlinux, t->name_off);
- addr = kallsyms_lookup_name(sym_name);
- if (!addr) {
- verbose(env, "ldimm64 failed to find the address for kernel symbol '%s'.\n",
- sym_name);
- return -ENOENT;
- }
- datasec_id = btf_find_by_name_kind(btf_vmlinux, ".data..percpu",
- BTF_KIND_DATASEC);
- if (datasec_id > 0) {
- datasec = btf_type_by_id(btf_vmlinux, datasec_id);
- for_each_vsi(i, datasec, vsi) {
- if (vsi->type == id) {
- percpu = true;
- break;
- }
- }
- }
- insn[0].imm = (u32)addr;
- insn[1].imm = addr >> 32;
- type = t->type;
- t = btf_type_skip_modifiers(btf_vmlinux, type, NULL);
- if (percpu) {
- aux->btf_var.reg_type = PTR_TO_PERCPU_BTF_ID;
- aux->btf_var.btf_id = type;
- } else if (!btf_type_is_struct(t)) {
- const struct btf_type *ret;
- const char *tname;
- u32 tsize;
- /* resolve the type size of ksym. */
- ret = btf_resolve_size(btf_vmlinux, t, &tsize);
- if (IS_ERR(ret)) {
- tname = btf_name_by_offset(btf_vmlinux, t->name_off);
- verbose(env, "ldimm64 unable to resolve the size of type '%s': %ld\n",
- tname, PTR_ERR(ret));
- return -EINVAL;
- }
- aux->btf_var.reg_type = PTR_TO_MEM;
- aux->btf_var.mem_size = tsize;
- } else {
- aux->btf_var.reg_type = PTR_TO_BTF_ID;
- aux->btf_var.btf_id = type;
- }
- return 0;
- }
- static int check_map_prealloc(struct bpf_map *map)
- {
- return (map->map_type != BPF_MAP_TYPE_HASH &&
- map->map_type != BPF_MAP_TYPE_PERCPU_HASH &&
- map->map_type != BPF_MAP_TYPE_HASH_OF_MAPS) ||
- !(map->map_flags & BPF_F_NO_PREALLOC);
- }
- static bool is_tracing_prog_type(enum bpf_prog_type type)
- {
- switch (type) {
- case BPF_PROG_TYPE_KPROBE:
- case BPF_PROG_TYPE_TRACEPOINT:
- case BPF_PROG_TYPE_PERF_EVENT:
- case BPF_PROG_TYPE_RAW_TRACEPOINT:
- return true;
- default:
- return false;
- }
- }
- static bool is_preallocated_map(struct bpf_map *map)
- {
- if (!check_map_prealloc(map))
- return false;
- if (map->inner_map_meta && !check_map_prealloc(map->inner_map_meta))
- return false;
- return true;
- }
- static int check_map_prog_compatibility(struct bpf_verifier_env *env,
- struct bpf_map *map,
- struct bpf_prog *prog)
- {
- enum bpf_prog_type prog_type = resolve_prog_type(prog);
- /*
- * Validate that trace type programs use preallocated hash maps.
- *
- * For programs attached to PERF events this is mandatory as the
- * perf NMI can hit any arbitrary code sequence.
- *
- * All other trace types using preallocated hash maps are unsafe as
- * well because tracepoint or kprobes can be inside locked regions
- * of the memory allocator or at a place where a recursion into the
- * memory allocator would see inconsistent state.
- *
- * On RT enabled kernels run-time allocation of all trace type
- * programs is strictly prohibited due to lock type constraints. On
- * !RT kernels it is allowed for backwards compatibility reasons for
- * now, but warnings are emitted so developers are made aware of
- * the unsafety and can fix their programs before this is enforced.
- */
- if (is_tracing_prog_type(prog_type) && !is_preallocated_map(map)) {
- if (prog_type == BPF_PROG_TYPE_PERF_EVENT) {
- verbose(env, "perf_event programs can only use preallocated hash map\n");
- return -EINVAL;
- }
- if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
- verbose(env, "trace type programs can only use preallocated hash map\n");
- return -EINVAL;
- }
- WARN_ONCE(1, "trace type BPF program uses run-time allocation\n");
- verbose(env, "trace type programs with run-time allocated hash maps are unsafe. Switch to preallocated hash maps.\n");
- }
- if ((is_tracing_prog_type(prog_type) ||
- prog_type == BPF_PROG_TYPE_SOCKET_FILTER) &&
- map_value_has_spin_lock(map)) {
- verbose(env, "tracing progs cannot use bpf_spin_lock yet\n");
- return -EINVAL;
- }
- if ((bpf_prog_is_dev_bound(prog->aux) || bpf_map_is_dev_bound(map)) &&
- !bpf_offload_prog_map_match(prog, map)) {
- verbose(env, "offload device mismatch between prog and map\n");
- return -EINVAL;
- }
- if (map->map_type == BPF_MAP_TYPE_STRUCT_OPS) {
- verbose(env, "bpf_struct_ops map cannot be used in prog\n");
- return -EINVAL;
- }
- if (prog->aux->sleepable)
- switch (map->map_type) {
- case BPF_MAP_TYPE_HASH:
- case BPF_MAP_TYPE_LRU_HASH:
- case BPF_MAP_TYPE_ARRAY:
- if (!is_preallocated_map(map)) {
- verbose(env,
- "Sleepable programs can only use preallocated hash maps\n");
- return -EINVAL;
- }
- break;
- default:
- verbose(env,
- "Sleepable programs can only use array and hash maps\n");
- return -EINVAL;
- }
- return 0;
- }
- static bool bpf_map_is_cgroup_storage(struct bpf_map *map)
- {
- return (map->map_type == BPF_MAP_TYPE_CGROUP_STORAGE ||
- map->map_type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE);
- }
- /* find and rewrite pseudo imm in ld_imm64 instructions:
- *
- * 1. if it accesses map FD, replace it with actual map pointer.
- * 2. if it accesses btf_id of a VAR, replace it with pointer to the var.
- *
- * NOTE: btf_vmlinux is required for converting pseudo btf_id.
- */
- static int resolve_pseudo_ldimm64(struct bpf_verifier_env *env)
- {
- struct bpf_insn *insn = env->prog->insnsi;
- int insn_cnt = env->prog->len;
- int i, j, err;
- err = bpf_prog_calc_tag(env->prog);
- if (err)
- return err;
- for (i = 0; i < insn_cnt; i++, insn++) {
- if (BPF_CLASS(insn->code) == BPF_LDX &&
- (BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) {
- verbose(env, "BPF_LDX uses reserved fields\n");
- return -EINVAL;
- }
- if (BPF_CLASS(insn->code) == BPF_STX &&
- ((BPF_MODE(insn->code) != BPF_MEM &&
- BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) {
- verbose(env, "BPF_STX uses reserved fields\n");
- return -EINVAL;
- }
- if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
- struct bpf_insn_aux_data *aux;
- struct bpf_map *map;
- struct fd f;
- u64 addr;
- if (i == insn_cnt - 1 || insn[1].code != 0 ||
- insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
- insn[1].off != 0) {
- verbose(env, "invalid bpf_ld_imm64 insn\n");
- return -EINVAL;
- }
- if (insn[0].src_reg == 0)
- /* valid generic load 64-bit imm */
- goto next_insn;
- if (insn[0].src_reg == BPF_PSEUDO_BTF_ID) {
- aux = &env->insn_aux_data[i];
- err = check_pseudo_btf_id(env, insn, aux);
- if (err)
- return err;
- goto next_insn;
- }
- /* In final convert_pseudo_ld_imm64() step, this is
- * converted into regular 64-bit imm load insn.
- */
- if ((insn[0].src_reg != BPF_PSEUDO_MAP_FD &&
- insn[0].src_reg != BPF_PSEUDO_MAP_VALUE) ||
- (insn[0].src_reg == BPF_PSEUDO_MAP_FD &&
- insn[1].imm != 0)) {
- verbose(env,
- "unrecognized bpf_ld_imm64 insn\n");
- return -EINVAL;
- }
- f = fdget(insn[0].imm);
- map = __bpf_map_get(f);
- if (IS_ERR(map)) {
- verbose(env, "fd %d is not pointing to valid bpf_map\n",
- insn[0].imm);
- return PTR_ERR(map);
- }
- err = check_map_prog_compatibility(env, map, env->prog);
- if (err) {
- fdput(f);
- return err;
- }
- aux = &env->insn_aux_data[i];
- if (insn->src_reg == BPF_PSEUDO_MAP_FD) {
- addr = (unsigned long)map;
- } else {
- u32 off = insn[1].imm;
- if (off >= BPF_MAX_VAR_OFF) {
- verbose(env, "direct value offset of %u is not allowed\n", off);
- fdput(f);
- return -EINVAL;
- }
- if (!map->ops->map_direct_value_addr) {
- verbose(env, "no direct value access support for this map type\n");
- fdput(f);
- return -EINVAL;
- }
- err = map->ops->map_direct_value_addr(map, &addr, off);
- if (err) {
- verbose(env, "invalid access to map value pointer, value_size=%u off=%u\n",
- map->value_size, off);
- fdput(f);
- return err;
- }
- aux->map_off = off;
- addr += off;
- }
- insn[0].imm = (u32)addr;
- insn[1].imm = addr >> 32;
- /* check whether we recorded this map already */
- for (j = 0; j < env->used_map_cnt; j++) {
- if (env->used_maps[j] == map) {
- aux->map_index = j;
- fdput(f);
- goto next_insn;
- }
- }
- if (env->used_map_cnt >= MAX_USED_MAPS) {
- fdput(f);
- return -E2BIG;
- }
- /* hold the map. If the program is rejected by verifier,
- * the map will be released by release_maps() or it
- * will be used by the valid program until it's unloaded
- * and all maps are released in free_used_maps()
- */
- bpf_map_inc(map);
- aux->map_index = env->used_map_cnt;
- env->used_maps[env->used_map_cnt++] = map;
- if (bpf_map_is_cgroup_storage(map) &&
- bpf_cgroup_storage_assign(env->prog->aux, map)) {
- verbose(env, "only one cgroup storage of each type is allowed\n");
- fdput(f);
- return -EBUSY;
- }
- fdput(f);
- next_insn:
- insn++;
- i++;
- continue;
- }
- /* Basic sanity check before we invest more work here. */
- if (!bpf_opcode_in_insntable(insn->code)) {
- verbose(env, "unknown opcode %02x\n", insn->code);
- return -EINVAL;
- }
- }
- /* now all pseudo BPF_LD_IMM64 instructions load valid
- * 'struct bpf_map *' into a register instead of user map_fd.
- * These pointers will be used later by verifier to validate map access.
- */
- return 0;
- }
- /* drop refcnt of maps used by the rejected program */
- static void release_maps(struct bpf_verifier_env *env)
- {
- __bpf_free_used_maps(env->prog->aux, env->used_maps,
- env->used_map_cnt);
- }
- /* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
- static void convert_pseudo_ld_imm64(struct bpf_verifier_env *env)
- {
- struct bpf_insn *insn = env->prog->insnsi;
- int insn_cnt = env->prog->len;
- int i;
- for (i = 0; i < insn_cnt; i++, insn++)
- if (insn->code == (BPF_LD | BPF_IMM | BPF_DW))
- insn->src_reg = 0;
- }
- /* single env->prog->insni[off] instruction was replaced with the range
- * insni[off, off + cnt). Adjust corresponding insn_aux_data by copying
- * [0, off) and [off, end) to new locations, so the patched range stays zero
- */
- static void adjust_insn_aux_data(struct bpf_verifier_env *env,
- struct bpf_insn_aux_data *new_data,
- struct bpf_prog *new_prog, u32 off, u32 cnt)
- {
- struct bpf_insn_aux_data *old_data = env->insn_aux_data;
- struct bpf_insn *insn = new_prog->insnsi;
- u32 old_seen = old_data[off].seen;
- u32 prog_len;
- int i;
- /* aux info at OFF always needs adjustment, no matter fast path
- * (cnt == 1) is taken or not. There is no guarantee INSN at OFF is the
- * original insn at old prog.
- */
- old_data[off].zext_dst = insn_has_def32(env, insn + off + cnt - 1);
- if (cnt == 1)
- return;
- prog_len = new_prog->len;
- memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
- memcpy(new_data + off + cnt - 1, old_data + off,
- sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
- for (i = off; i < off + cnt - 1; i++) {
- /* Expand insni[off]'s seen count to the patched range. */
- new_data[i].seen = old_seen;
- new_data[i].zext_dst = insn_has_def32(env, insn + i);
- }
- env->insn_aux_data = new_data;
- vfree(old_data);
- }
- static void adjust_subprog_starts(struct bpf_verifier_env *env, u32 off, u32 len)
- {
- int i;
- if (len == 1)
- return;
- /* NOTE: fake 'exit' subprog should be updated as well. */
- for (i = 0; i <= env->subprog_cnt; i++) {
- if (env->subprog_info[i].start <= off)
- continue;
- env->subprog_info[i].start += len - 1;
- }
- }
- static void adjust_poke_descs(struct bpf_prog *prog, u32 off, u32 len)
- {
- struct bpf_jit_poke_descriptor *tab = prog->aux->poke_tab;
- int i, sz = prog->aux->size_poke_tab;
- struct bpf_jit_poke_descriptor *desc;
- for (i = 0; i < sz; i++) {
- desc = &tab[i];
- if (desc->insn_idx <= off)
- continue;
- desc->insn_idx += len - 1;
- }
- }
- static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off,
- const struct bpf_insn *patch, u32 len)
- {
- struct bpf_prog *new_prog;
- struct bpf_insn_aux_data *new_data = NULL;
- if (len > 1) {
- new_data = vzalloc(array_size(env->prog->len + len - 1,
- sizeof(struct bpf_insn_aux_data)));
- if (!new_data)
- return NULL;
- }
- new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
- if (IS_ERR(new_prog)) {
- if (PTR_ERR(new_prog) == -ERANGE)
- verbose(env,
- "insn %d cannot be patched due to 16-bit range\n",
- env->insn_aux_data[off].orig_idx);
- vfree(new_data);
- return NULL;
- }
- adjust_insn_aux_data(env, new_data, new_prog, off, len);
- adjust_subprog_starts(env, off, len);
- adjust_poke_descs(new_prog, off, len);
- return new_prog;
- }
- static int adjust_subprog_starts_after_remove(struct bpf_verifier_env *env,
- u32 off, u32 cnt)
- {
- int i, j;
- /* find first prog starting at or after off (first to remove) */
- for (i = 0; i < env->subprog_cnt; i++)
- if (env->subprog_info[i].start >= off)
- break;
- /* find first prog starting at or after off + cnt (first to stay) */
- for (j = i; j < env->subprog_cnt; j++)
- if (env->subprog_info[j].start >= off + cnt)
- break;
- /* if j doesn't start exactly at off + cnt, we are just removing
- * the front of previous prog
- */
- if (env->subprog_info[j].start != off + cnt)
- j--;
- if (j > i) {
- struct bpf_prog_aux *aux = env->prog->aux;
- int move;
- /* move fake 'exit' subprog as well */
- move = env->subprog_cnt + 1 - j;
- memmove(env->subprog_info + i,
- env->subprog_info + j,
- sizeof(*env->subprog_info) * move);
- env->subprog_cnt -= j - i;
- /* remove func_info */
- if (aux->func_info) {
- move = aux->func_info_cnt - j;
- memmove(aux->func_info + i,
- aux->func_info + j,
- sizeof(*aux->func_info) * move);
- aux->func_info_cnt -= j - i;
- /* func_info->insn_off is set after all code rewrites,
- * in adjust_btf_func() - no need to adjust
- */
- }
- } else {
- /* convert i from "first prog to remove" to "first to adjust" */
- if (env->subprog_info[i].start == off)
- i++;
- }
- /* update fake 'exit' subprog as well */
- for (; i <= env->subprog_cnt; i++)
- env->subprog_info[i].start -= cnt;
- return 0;
- }
- static int bpf_adj_linfo_after_remove(struct bpf_verifier_env *env, u32 off,
- u32 cnt)
- {
- struct bpf_prog *prog = env->prog;
- u32 i, l_off, l_cnt, nr_linfo;
- struct bpf_line_info *linfo;
- nr_linfo = prog->aux->nr_linfo;
- if (!nr_linfo)
- return 0;
- linfo = prog->aux->linfo;
- /* find first line info to remove, count lines to be removed */
- for (i = 0; i < nr_linfo; i++)
- if (linfo[i].insn_off >= off)
- break;
- l_off = i;
- l_cnt = 0;
- for (; i < nr_linfo; i++)
- if (linfo[i].insn_off < off + cnt)
- l_cnt++;
- else
- break;
- /* First live insn doesn't match first live linfo, it needs to "inherit"
- * last removed linfo. prog is already modified, so prog->len == off
- * means no live instructions after (tail of the program was removed).
- */
- if (prog->len != off && l_cnt &&
- (i == nr_linfo || linfo[i].insn_off != off + cnt)) {
- l_cnt--;
- linfo[--i].insn_off = off + cnt;
- }
- /* remove the line info which refer to the removed instructions */
- if (l_cnt) {
- memmove(linfo + l_off, linfo + i,
- sizeof(*linfo) * (nr_linfo - i));
- prog->aux->nr_linfo -= l_cnt;
- nr_linfo = prog->aux->nr_linfo;
- }
- /* pull all linfo[i].insn_off >= off + cnt in by cnt */
- for (i = l_off; i < nr_linfo; i++)
- linfo[i].insn_off -= cnt;
- /* fix up all subprogs (incl. 'exit') which start >= off */
- for (i = 0; i <= env->subprog_cnt; i++)
- if (env->subprog_info[i].linfo_idx > l_off) {
- /* program may have started in the removed region but
- * may not be fully removed
- */
- if (env->subprog_info[i].linfo_idx >= l_off + l_cnt)
- env->subprog_info[i].linfo_idx -= l_cnt;
- else
- env->subprog_info[i].linfo_idx = l_off;
- }
- return 0;
- }
- static int verifier_remove_insns(struct bpf_verifier_env *env, u32 off, u32 cnt)
- {
- struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
- unsigned int orig_prog_len = env->prog->len;
- int err;
- if (bpf_prog_is_dev_bound(env->prog->aux))
- bpf_prog_offload_remove_insns(env, off, cnt);
- err = bpf_remove_insns(env->prog, off, cnt);
- if (err)
- return err;
- err = adjust_subprog_starts_after_remove(env, off, cnt);
- if (err)
- return err;
- err = bpf_adj_linfo_after_remove(env, off, cnt);
- if (err)
- return err;
- memmove(aux_data + off, aux_data + off + cnt,
- sizeof(*aux_data) * (orig_prog_len - off - cnt));
- return 0;
- }
- /* The verifier does more data flow analysis than llvm and will not
- * explore branches that are dead at run time. Malicious programs can
- * have dead code too. Therefore replace all dead at-run-time code
- * with 'ja -1'.
- *
- * Just nops are not optimal, e.g. if they would sit at the end of the
- * program and through another bug we would manage to jump there, then
- * we'd execute beyond program memory otherwise. Returning exception
- * code also wouldn't work since we can have subprogs where the dead
- * code could be located.
- */
- static void sanitize_dead_code(struct bpf_verifier_env *env)
- {
- struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
- struct bpf_insn trap = BPF_JMP_IMM(BPF_JA, 0, 0, -1);
- struct bpf_insn *insn = env->prog->insnsi;
- const int insn_cnt = env->prog->len;
- int i;
- for (i = 0; i < insn_cnt; i++) {
- if (aux_data[i].seen)
- continue;
- memcpy(insn + i, &trap, sizeof(trap));
- aux_data[i].zext_dst = false;
- }
- }
- static bool insn_is_cond_jump(u8 code)
- {
- u8 op;
- if (BPF_CLASS(code) == BPF_JMP32)
- return true;
- if (BPF_CLASS(code) != BPF_JMP)
- return false;
- op = BPF_OP(code);
- return op != BPF_JA && op != BPF_EXIT && op != BPF_CALL;
- }
- static void opt_hard_wire_dead_code_branches(struct bpf_verifier_env *env)
- {
- struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
- struct bpf_insn ja = BPF_JMP_IMM(BPF_JA, 0, 0, 0);
- struct bpf_insn *insn = env->prog->insnsi;
- const int insn_cnt = env->prog->len;
- int i;
- for (i = 0; i < insn_cnt; i++, insn++) {
- if (!insn_is_cond_jump(insn->code))
- continue;
- if (!aux_data[i + 1].seen)
- ja.off = insn->off;
- else if (!aux_data[i + 1 + insn->off].seen)
- ja.off = 0;
- else
- continue;
- if (bpf_prog_is_dev_bound(env->prog->aux))
- bpf_prog_offload_replace_insn(env, i, &ja);
- memcpy(insn, &ja, sizeof(ja));
- }
- }
- static int opt_remove_dead_code(struct bpf_verifier_env *env)
- {
- struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
- int insn_cnt = env->prog->len;
- int i, err;
- for (i = 0; i < insn_cnt; i++) {
- int j;
- j = 0;
- while (i + j < insn_cnt && !aux_data[i + j].seen)
- j++;
- if (!j)
- continue;
- err = verifier_remove_insns(env, i, j);
- if (err)
- return err;
- insn_cnt = env->prog->len;
- }
- return 0;
- }
- static int opt_remove_nops(struct bpf_verifier_env *env)
- {
- const struct bpf_insn ja = BPF_JMP_IMM(BPF_JA, 0, 0, 0);
- struct bpf_insn *insn = env->prog->insnsi;
- int insn_cnt = env->prog->len;
- int i, err;
- for (i = 0; i < insn_cnt; i++) {
- if (memcmp(&insn[i], &ja, sizeof(ja)))
- continue;
- err = verifier_remove_insns(env, i, 1);
- if (err)
- return err;
- insn_cnt--;
- i--;
- }
- return 0;
- }
- static int opt_subreg_zext_lo32_rnd_hi32(struct bpf_verifier_env *env,
- const union bpf_attr *attr)
- {
- struct bpf_insn *patch, zext_patch[2], rnd_hi32_patch[4];
- struct bpf_insn_aux_data *aux = env->insn_aux_data;
- int i, patch_len, delta = 0, len = env->prog->len;
- struct bpf_insn *insns = env->prog->insnsi;
- struct bpf_prog *new_prog;
- bool rnd_hi32;
- rnd_hi32 = attr->prog_flags & BPF_F_TEST_RND_HI32;
- zext_patch[1] = BPF_ZEXT_REG(0);
- rnd_hi32_patch[1] = BPF_ALU64_IMM(BPF_MOV, BPF_REG_AX, 0);
- rnd_hi32_patch[2] = BPF_ALU64_IMM(BPF_LSH, BPF_REG_AX, 32);
- rnd_hi32_patch[3] = BPF_ALU64_REG(BPF_OR, 0, BPF_REG_AX);
- for (i = 0; i < len; i++) {
- int adj_idx = i + delta;
- struct bpf_insn insn;
- insn = insns[adj_idx];
- if (!aux[adj_idx].zext_dst) {
- u8 code, class;
- u32 imm_rnd;
- if (!rnd_hi32)
- continue;
- code = insn.code;
- class = BPF_CLASS(code);
- if (insn_no_def(&insn))
- continue;
- /* NOTE: arg "reg" (the fourth one) is only used for
- * BPF_STX which has been ruled out in above
- * check, it is safe to pass NULL here.
- */
- if (is_reg64(env, &insn, insn.dst_reg, NULL, DST_OP)) {
- if (class == BPF_LD &&
- BPF_MODE(code) == BPF_IMM)
- i++;
- continue;
- }
- /* ctx load could be transformed into wider load. */
- if (class == BPF_LDX &&
- aux[adj_idx].ptr_type == PTR_TO_CTX)
- continue;
- imm_rnd = get_random_int();
- rnd_hi32_patch[0] = insn;
- rnd_hi32_patch[1].imm = imm_rnd;
- rnd_hi32_patch[3].dst_reg = insn.dst_reg;
- patch = rnd_hi32_patch;
- patch_len = 4;
- goto apply_patch_buffer;
- }
- if (!bpf_jit_needs_zext())
- continue;
- zext_patch[0] = insn;
- zext_patch[1].dst_reg = insn.dst_reg;
- zext_patch[1].src_reg = insn.dst_reg;
- patch = zext_patch;
- patch_len = 2;
- apply_patch_buffer:
- new_prog = bpf_patch_insn_data(env, adj_idx, patch, patch_len);
- if (!new_prog)
- return -ENOMEM;
- env->prog = new_prog;
- insns = new_prog->insnsi;
- aux = env->insn_aux_data;
- delta += patch_len - 1;
- }
- return 0;
- }
- /* convert load instructions that access fields of a context type into a
- * sequence of instructions that access fields of the underlying structure:
- * struct __sk_buff -> struct sk_buff
- * struct bpf_sock_ops -> struct sock
- */
- static int convert_ctx_accesses(struct bpf_verifier_env *env)
- {
- const struct bpf_verifier_ops *ops = env->ops;
- int i, cnt, size, ctx_field_size, delta = 0;
- const int insn_cnt = env->prog->len;
- struct bpf_insn insn_buf[16], *insn;
- u32 target_size, size_default, off;
- struct bpf_prog *new_prog;
- enum bpf_access_type type;
- bool is_narrower_load;
- if (ops->gen_prologue || env->seen_direct_write) {
- if (!ops->gen_prologue) {
- verbose(env, "bpf verifier is misconfigured\n");
- return -EINVAL;
- }
- cnt = ops->gen_prologue(insn_buf, env->seen_direct_write,
- env->prog);
- if (cnt >= ARRAY_SIZE(insn_buf)) {
- verbose(env, "bpf verifier is misconfigured\n");
- return -EINVAL;
- } else if (cnt) {
- new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
- if (!new_prog)
- return -ENOMEM;
- env->prog = new_prog;
- delta += cnt - 1;
- }
- }
- if (bpf_prog_is_dev_bound(env->prog->aux))
- return 0;
- insn = env->prog->insnsi + delta;
- for (i = 0; i < insn_cnt; i++, insn++) {
- bpf_convert_ctx_access_t convert_ctx_access;
- bool ctx_access;
- if (insn->code == (BPF_LDX | BPF_MEM | BPF_B) ||
- insn->code == (BPF_LDX | BPF_MEM | BPF_H) ||
- insn->code == (BPF_LDX | BPF_MEM | BPF_W) ||
- insn->code == (BPF_LDX | BPF_MEM | BPF_DW)) {
- type = BPF_READ;
- ctx_access = true;
- } else if (insn->code == (BPF_STX | BPF_MEM | BPF_B) ||
- insn->code == (BPF_STX | BPF_MEM | BPF_H) ||
- insn->code == (BPF_STX | BPF_MEM | BPF_W) ||
- insn->code == (BPF_STX | BPF_MEM | BPF_DW) ||
- insn->code == (BPF_ST | BPF_MEM | BPF_B) ||
- insn->code == (BPF_ST | BPF_MEM | BPF_H) ||
- insn->code == (BPF_ST | BPF_MEM | BPF_W) ||
- insn->code == (BPF_ST | BPF_MEM | BPF_DW)) {
- type = BPF_WRITE;
- ctx_access = BPF_CLASS(insn->code) == BPF_STX;
- } else {
- continue;
- }
- if (type == BPF_WRITE &&
- env->insn_aux_data[i + delta].sanitize_stack_spill) {
- struct bpf_insn patch[] = {
- *insn,
- BPF_ST_NOSPEC(),
- };
- cnt = ARRAY_SIZE(patch);
- new_prog = bpf_patch_insn_data(env, i + delta, patch, cnt);
- if (!new_prog)
- return -ENOMEM;
- delta += cnt - 1;
- env->prog = new_prog;
- insn = new_prog->insnsi + i + delta;
- continue;
- }
- if (!ctx_access)
- continue;
- switch (env->insn_aux_data[i + delta].ptr_type) {
- case PTR_TO_CTX:
- if (!ops->convert_ctx_access)
- continue;
- convert_ctx_access = ops->convert_ctx_access;
- break;
- case PTR_TO_SOCKET:
- case PTR_TO_SOCK_COMMON:
- convert_ctx_access = bpf_sock_convert_ctx_access;
- break;
- case PTR_TO_TCP_SOCK:
- convert_ctx_access = bpf_tcp_sock_convert_ctx_access;
- break;
- case PTR_TO_XDP_SOCK:
- convert_ctx_access = bpf_xdp_sock_convert_ctx_access;
- break;
- case PTR_TO_BTF_ID:
- if (type == BPF_READ) {
- insn->code = BPF_LDX | BPF_PROBE_MEM |
- BPF_SIZE((insn)->code);
- env->prog->aux->num_exentries++;
- } else if (resolve_prog_type(env->prog) != BPF_PROG_TYPE_STRUCT_OPS) {
- verbose(env, "Writes through BTF pointers are not allowed\n");
- return -EINVAL;
- }
- continue;
- default:
- continue;
- }
- ctx_field_size = env->insn_aux_data[i + delta].ctx_field_size;
- size = BPF_LDST_BYTES(insn);
- /* If the read access is a narrower load of the field,
- * convert to a 4/8-byte load, to minimum program type specific
- * convert_ctx_access changes. If conversion is successful,
- * we will apply proper mask to the result.
- */
- is_narrower_load = size < ctx_field_size;
- size_default = bpf_ctx_off_adjust_machine(ctx_field_size);
- off = insn->off;
- if (is_narrower_load) {
- u8 size_code;
- if (type == BPF_WRITE) {
- verbose(env, "bpf verifier narrow ctx access misconfigured\n");
- return -EINVAL;
- }
- size_code = BPF_H;
- if (ctx_field_size == 4)
- size_code = BPF_W;
- else if (ctx_field_size == 8)
- size_code = BPF_DW;
- insn->off = off & ~(size_default - 1);
- insn->code = BPF_LDX | BPF_MEM | size_code;
- }
- target_size = 0;
- cnt = convert_ctx_access(type, insn, insn_buf, env->prog,
- &target_size);
- if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf) ||
- (ctx_field_size && !target_size)) {
- verbose(env, "bpf verifier is misconfigured\n");
- return -EINVAL;
- }
- if (is_narrower_load && size < target_size) {
- u8 shift = bpf_ctx_narrow_access_offset(
- off, size, size_default) * 8;
- if (shift && cnt + 1 >= ARRAY_SIZE(insn_buf)) {
- verbose(env, "bpf verifier narrow ctx load misconfigured\n");
- return -EINVAL;
- }
- if (ctx_field_size <= 4) {
- if (shift)
- insn_buf[cnt++] = BPF_ALU32_IMM(BPF_RSH,
- insn->dst_reg,
- shift);
- insn_buf[cnt++] = BPF_ALU32_IMM(BPF_AND, insn->dst_reg,
- (1 << size * 8) - 1);
- } else {
- if (shift)
- insn_buf[cnt++] = BPF_ALU64_IMM(BPF_RSH,
- insn->dst_reg,
- shift);
- insn_buf[cnt++] = BPF_ALU64_IMM(BPF_AND, insn->dst_reg,
- (1ULL << size * 8) - 1);
- }
- }
- new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
- if (!new_prog)
- return -ENOMEM;
- delta += cnt - 1;
- /* keep walking new program and skip insns we just inserted */
- env->prog = new_prog;
- insn = new_prog->insnsi + i + delta;
- }
- return 0;
- }
- static int jit_subprogs(struct bpf_verifier_env *env)
- {
- struct bpf_prog *prog = env->prog, **func, *tmp;
- int i, j, subprog_start, subprog_end = 0, len, subprog;
- struct bpf_map *map_ptr;
- struct bpf_insn *insn;
- void *old_bpf_func;
- int err, num_exentries;
- if (env->subprog_cnt <= 1)
- return 0;
- for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
- if (insn->code != (BPF_JMP | BPF_CALL) ||
- insn->src_reg != BPF_PSEUDO_CALL)
- continue;
- /* Upon error here we cannot fall back to interpreter but
- * need a hard reject of the program. Thus -EFAULT is
- * propagated in any case.
- */
- subprog = find_subprog(env, i + insn->imm + 1);
- if (subprog < 0) {
- WARN_ONCE(1, "verifier bug. No program starts at insn %d\n",
- i + insn->imm + 1);
- return -EFAULT;
- }
- /* temporarily remember subprog id inside insn instead of
- * aux_data, since next loop will split up all insns into funcs
- */
- insn->off = subprog;
- /* remember original imm in case JIT fails and fallback
- * to interpreter will be needed
- */
- env->insn_aux_data[i].call_imm = insn->imm;
- /* point imm to __bpf_call_base+1 from JITs point of view */
- insn->imm = 1;
- }
- err = bpf_prog_alloc_jited_linfo(prog);
- if (err)
- goto out_undo_insn;
- err = -ENOMEM;
- func = kcalloc(env->subprog_cnt, sizeof(prog), GFP_KERNEL);
- if (!func)
- goto out_undo_insn;
- for (i = 0; i < env->subprog_cnt; i++) {
- subprog_start = subprog_end;
- subprog_end = env->subprog_info[i + 1].start;
- len = subprog_end - subprog_start;
- /* BPF_PROG_RUN doesn't call subprogs directly,
- * hence main prog stats include the runtime of subprogs.
- * subprogs don't have IDs and not reachable via prog_get_next_id
- * func[i]->aux->stats will never be accessed and stays NULL
- */
- func[i] = bpf_prog_alloc_no_stats(bpf_prog_size(len), GFP_USER);
- if (!func[i])
- goto out_free;
- memcpy(func[i]->insnsi, &prog->insnsi[subprog_start],
- len * sizeof(struct bpf_insn));
- func[i]->type = prog->type;
- func[i]->len = len;
- if (bpf_prog_calc_tag(func[i]))
- goto out_free;
- func[i]->is_func = 1;
- func[i]->aux->func_idx = i;
- /* the btf and func_info will be freed only at prog->aux */
- func[i]->aux->btf = prog->aux->btf;
- func[i]->aux->func_info = prog->aux->func_info;
- for (j = 0; j < prog->aux->size_poke_tab; j++) {
- u32 insn_idx = prog->aux->poke_tab[j].insn_idx;
- int ret;
- if (!(insn_idx >= subprog_start &&
- insn_idx <= subprog_end))
- continue;
- ret = bpf_jit_add_poke_descriptor(func[i],
- &prog->aux->poke_tab[j]);
- if (ret < 0) {
- verbose(env, "adding tail call poke descriptor failed\n");
- goto out_free;
- }
- func[i]->insnsi[insn_idx - subprog_start].imm = ret + 1;
- map_ptr = func[i]->aux->poke_tab[ret].tail_call.map;
- ret = map_ptr->ops->map_poke_track(map_ptr, func[i]->aux);
- if (ret < 0) {
- verbose(env, "tracking tail call prog failed\n");
- goto out_free;
- }
- }
- /* Use bpf_prog_F_tag to indicate functions in stack traces.
- * Long term would need debug info to populate names
- */
- func[i]->aux->name[0] = 'F';
- func[i]->aux->stack_depth = env->subprog_info[i].stack_depth;
- func[i]->jit_requested = 1;
- func[i]->aux->linfo = prog->aux->linfo;
- func[i]->aux->nr_linfo = prog->aux->nr_linfo;
- func[i]->aux->jited_linfo = prog->aux->jited_linfo;
- func[i]->aux->linfo_idx = env->subprog_info[i].linfo_idx;
- num_exentries = 0;
- insn = func[i]->insnsi;
- for (j = 0; j < func[i]->len; j++, insn++) {
- if (BPF_CLASS(insn->code) == BPF_LDX &&
- BPF_MODE(insn->code) == BPF_PROBE_MEM)
- num_exentries++;
- }
- func[i]->aux->num_exentries = num_exentries;
- func[i]->aux->tail_call_reachable = env->subprog_info[i].tail_call_reachable;
- func[i] = bpf_int_jit_compile(func[i]);
- if (!func[i]->jited) {
- err = -ENOTSUPP;
- goto out_free;
- }
- cond_resched();
- }
- /* Untrack main program's aux structs so that during map_poke_run()
- * we will not stumble upon the unfilled poke descriptors; each
- * of the main program's poke descs got distributed across subprogs
- * and got tracked onto map, so we are sure that none of them will
- * be missed after the operation below
- */
- for (i = 0; i < prog->aux->size_poke_tab; i++) {
- map_ptr = prog->aux->poke_tab[i].tail_call.map;
- map_ptr->ops->map_poke_untrack(map_ptr, prog->aux);
- }
- /* at this point all bpf functions were successfully JITed
- * now populate all bpf_calls with correct addresses and
- * run last pass of JIT
- */
- for (i = 0; i < env->subprog_cnt; i++) {
- insn = func[i]->insnsi;
- for (j = 0; j < func[i]->len; j++, insn++) {
- if (insn->code != (BPF_JMP | BPF_CALL) ||
- insn->src_reg != BPF_PSEUDO_CALL)
- continue;
- subprog = insn->off;
- insn->imm = BPF_CAST_CALL(func[subprog]->bpf_func) -
- __bpf_call_base;
- }
- /* we use the aux data to keep a list of the start addresses
- * of the JITed images for each function in the program
- *
- * for some architectures, such as powerpc64, the imm field
- * might not be large enough to hold the offset of the start
- * address of the callee's JITed image from __bpf_call_base
- *
- * in such cases, we can lookup the start address of a callee
- * by using its subprog id, available from the off field of
- * the call instruction, as an index for this list
- */
- func[i]->aux->func = func;
- func[i]->aux->func_cnt = env->subprog_cnt;
- }
- for (i = 0; i < env->subprog_cnt; i++) {
- old_bpf_func = func[i]->bpf_func;
- tmp = bpf_int_jit_compile(func[i]);
- if (tmp != func[i] || func[i]->bpf_func != old_bpf_func) {
- verbose(env, "JIT doesn't support bpf-to-bpf calls\n");
- err = -ENOTSUPP;
- goto out_free;
- }
- cond_resched();
- }
- /* finally lock prog and jit images for all functions and
- * populate kallsysm
- */
- for (i = 0; i < env->subprog_cnt; i++) {
- bpf_prog_lock_ro(func[i]);
- bpf_prog_kallsyms_add(func[i]);
- }
- /* Last step: make now unused interpreter insns from main
- * prog consistent for later dump requests, so they can
- * later look the same as if they were interpreted only.
- */
- for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
- if (insn->code != (BPF_JMP | BPF_CALL) ||
- insn->src_reg != BPF_PSEUDO_CALL)
- continue;
- insn->off = env->insn_aux_data[i].call_imm;
- subprog = find_subprog(env, i + insn->off + 1);
- insn->imm = subprog;
- }
- prog->jited = 1;
- prog->bpf_func = func[0]->bpf_func;
- prog->aux->func = func;
- prog->aux->func_cnt = env->subprog_cnt;
- bpf_prog_free_unused_jited_linfo(prog);
- return 0;
- out_free:
- for (i = 0; i < env->subprog_cnt; i++) {
- if (!func[i])
- continue;
- for (j = 0; j < func[i]->aux->size_poke_tab; j++) {
- map_ptr = func[i]->aux->poke_tab[j].tail_call.map;
- map_ptr->ops->map_poke_untrack(map_ptr, func[i]->aux);
- }
- bpf_jit_free(func[i]);
- }
- kfree(func);
- out_undo_insn:
- /* cleanup main prog to be interpreted */
- prog->jit_requested = 0;
- for (i = 0, insn = prog->insnsi; i < prog->len; i++, insn++) {
- if (insn->code != (BPF_JMP | BPF_CALL) ||
- insn->src_reg != BPF_PSEUDO_CALL)
- continue;
- insn->off = 0;
- insn->imm = env->insn_aux_data[i].call_imm;
- }
- bpf_prog_free_jited_linfo(prog);
- return err;
- }
- static int fixup_call_args(struct bpf_verifier_env *env)
- {
- #ifndef CONFIG_BPF_JIT_ALWAYS_ON
- struct bpf_prog *prog = env->prog;
- struct bpf_insn *insn = prog->insnsi;
- int i, depth;
- #endif
- int err = 0;
- if (env->prog->jit_requested &&
- !bpf_prog_is_dev_bound(env->prog->aux)) {
- err = jit_subprogs(env);
- if (err == 0)
- return 0;
- if (err == -EFAULT)
- return err;
- }
- #ifndef CONFIG_BPF_JIT_ALWAYS_ON
- if (env->subprog_cnt > 1 && env->prog->aux->tail_call_reachable) {
- /* When JIT fails the progs with bpf2bpf calls and tail_calls
- * have to be rejected, since interpreter doesn't support them yet.
- */
- verbose(env, "tail_calls are not allowed in non-JITed programs with bpf-to-bpf calls\n");
- return -EINVAL;
- }
- for (i = 0; i < prog->len; i++, insn++) {
- if (insn->code != (BPF_JMP | BPF_CALL) ||
- insn->src_reg != BPF_PSEUDO_CALL)
- continue;
- depth = get_callee_stack_depth(env, insn, i);
- if (depth < 0)
- return depth;
- bpf_patch_call_args(insn, depth);
- }
- err = 0;
- #endif
- return err;
- }
- /* fixup insn->imm field of bpf_call instructions
- * and inline eligible helpers as explicit sequence of BPF instructions
- *
- * this function is called after eBPF program passed verification
- */
- static int fixup_bpf_calls(struct bpf_verifier_env *env)
- {
- struct bpf_prog *prog = env->prog;
- bool expect_blinding = bpf_jit_blinding_enabled(prog);
- struct bpf_insn *insn = prog->insnsi;
- const struct bpf_func_proto *fn;
- const int insn_cnt = prog->len;
- const struct bpf_map_ops *ops;
- struct bpf_insn_aux_data *aux;
- struct bpf_insn insn_buf[16];
- struct bpf_prog *new_prog;
- struct bpf_map *map_ptr;
- int i, ret, cnt, delta = 0;
- for (i = 0; i < insn_cnt; i++, insn++) {
- if (insn->code == (BPF_ALU64 | BPF_MOD | BPF_X) ||
- insn->code == (BPF_ALU64 | BPF_DIV | BPF_X) ||
- insn->code == (BPF_ALU | BPF_MOD | BPF_X) ||
- insn->code == (BPF_ALU | BPF_DIV | BPF_X)) {
- bool is64 = BPF_CLASS(insn->code) == BPF_ALU64;
- bool isdiv = BPF_OP(insn->code) == BPF_DIV;
- struct bpf_insn *patchlet;
- struct bpf_insn chk_and_div[] = {
- /* [R,W]x div 0 -> 0 */
- BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
- BPF_JNE | BPF_K, insn->src_reg,
- 0, 2, 0),
- BPF_ALU32_REG(BPF_XOR, insn->dst_reg, insn->dst_reg),
- BPF_JMP_IMM(BPF_JA, 0, 0, 1),
- *insn,
- };
- struct bpf_insn chk_and_mod[] = {
- /* [R,W]x mod 0 -> [R,W]x */
- BPF_RAW_INSN((is64 ? BPF_JMP : BPF_JMP32) |
- BPF_JEQ | BPF_K, insn->src_reg,
- 0, 1 + (is64 ? 0 : 1), 0),
- *insn,
- BPF_JMP_IMM(BPF_JA, 0, 0, 1),
- BPF_MOV32_REG(insn->dst_reg, insn->dst_reg),
- };
- patchlet = isdiv ? chk_and_div : chk_and_mod;
- cnt = isdiv ? ARRAY_SIZE(chk_and_div) :
- ARRAY_SIZE(chk_and_mod) - (is64 ? 2 : 0);
- new_prog = bpf_patch_insn_data(env, i + delta, patchlet, cnt);
- if (!new_prog)
- return -ENOMEM;
- delta += cnt - 1;
- env->prog = prog = new_prog;
- insn = new_prog->insnsi + i + delta;
- continue;
- }
- if (BPF_CLASS(insn->code) == BPF_LD &&
- (BPF_MODE(insn->code) == BPF_ABS ||
- BPF_MODE(insn->code) == BPF_IND)) {
- cnt = env->ops->gen_ld_abs(insn, insn_buf);
- if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
- verbose(env, "bpf verifier is misconfigured\n");
- return -EINVAL;
- }
- new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
- if (!new_prog)
- return -ENOMEM;
- delta += cnt - 1;
- env->prog = prog = new_prog;
- insn = new_prog->insnsi + i + delta;
- continue;
- }
- if (insn->code == (BPF_ALU64 | BPF_ADD | BPF_X) ||
- insn->code == (BPF_ALU64 | BPF_SUB | BPF_X)) {
- const u8 code_add = BPF_ALU64 | BPF_ADD | BPF_X;
- const u8 code_sub = BPF_ALU64 | BPF_SUB | BPF_X;
- struct bpf_insn insn_buf[16];
- struct bpf_insn *patch = &insn_buf[0];
- bool issrc, isneg, isimm;
- u32 off_reg;
- aux = &env->insn_aux_data[i + delta];
- if (!aux->alu_state ||
- aux->alu_state == BPF_ALU_NON_POINTER)
- continue;
- isneg = aux->alu_state & BPF_ALU_NEG_VALUE;
- issrc = (aux->alu_state & BPF_ALU_SANITIZE) ==
- BPF_ALU_SANITIZE_SRC;
- isimm = aux->alu_state & BPF_ALU_IMMEDIATE;
- off_reg = issrc ? insn->src_reg : insn->dst_reg;
- if (isimm) {
- *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
- } else {
- if (isneg)
- *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
- *patch++ = BPF_MOV32_IMM(BPF_REG_AX, aux->alu_limit);
- *patch++ = BPF_ALU64_REG(BPF_SUB, BPF_REG_AX, off_reg);
- *patch++ = BPF_ALU64_REG(BPF_OR, BPF_REG_AX, off_reg);
- *patch++ = BPF_ALU64_IMM(BPF_NEG, BPF_REG_AX, 0);
- *patch++ = BPF_ALU64_IMM(BPF_ARSH, BPF_REG_AX, 63);
- *patch++ = BPF_ALU64_REG(BPF_AND, BPF_REG_AX, off_reg);
- }
- if (!issrc)
- *patch++ = BPF_MOV64_REG(insn->dst_reg, insn->src_reg);
- insn->src_reg = BPF_REG_AX;
- if (isneg)
- insn->code = insn->code == code_add ?
- code_sub : code_add;
- *patch++ = *insn;
- if (issrc && isneg && !isimm)
- *patch++ = BPF_ALU64_IMM(BPF_MUL, off_reg, -1);
- cnt = patch - insn_buf;
- new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
- if (!new_prog)
- return -ENOMEM;
- delta += cnt - 1;
- env->prog = prog = new_prog;
- insn = new_prog->insnsi + i + delta;
- continue;
- }
- if (insn->code != (BPF_JMP | BPF_CALL))
- continue;
- if (insn->src_reg == BPF_PSEUDO_CALL)
- continue;
- if (insn->imm == BPF_FUNC_get_route_realm)
- prog->dst_needed = 1;
- if (insn->imm == BPF_FUNC_get_prandom_u32)
- bpf_user_rnd_init_once();
- if (insn->imm == BPF_FUNC_override_return)
- prog->kprobe_override = 1;
- if (insn->imm == BPF_FUNC_tail_call) {
- /* If we tail call into other programs, we
- * cannot make any assumptions since they can
- * be replaced dynamically during runtime in
- * the program array.
- */
- prog->cb_access = 1;
- if (!allow_tail_call_in_subprogs(env))
- prog->aux->stack_depth = MAX_BPF_STACK;
- prog->aux->max_pkt_offset = MAX_PACKET_OFF;
- /* mark bpf_tail_call as different opcode to avoid
- * conditional branch in the interpeter for every normal
- * call and to prevent accidental JITing by JIT compiler
- * that doesn't support bpf_tail_call yet
- */
- insn->imm = 0;
- insn->code = BPF_JMP | BPF_TAIL_CALL;
- aux = &env->insn_aux_data[i + delta];
- if (env->bpf_capable && !expect_blinding &&
- prog->jit_requested &&
- !bpf_map_key_poisoned(aux) &&
- !bpf_map_ptr_poisoned(aux) &&
- !bpf_map_ptr_unpriv(aux)) {
- struct bpf_jit_poke_descriptor desc = {
- .reason = BPF_POKE_REASON_TAIL_CALL,
- .tail_call.map = BPF_MAP_PTR(aux->map_ptr_state),
- .tail_call.key = bpf_map_key_immediate(aux),
- .insn_idx = i + delta,
- };
- ret = bpf_jit_add_poke_descriptor(prog, &desc);
- if (ret < 0) {
- verbose(env, "adding tail call poke descriptor failed\n");
- return ret;
- }
- insn->imm = ret + 1;
- continue;
- }
- if (!bpf_map_ptr_unpriv(aux))
- continue;
- /* instead of changing every JIT dealing with tail_call
- * emit two extra insns:
- * if (index >= max_entries) goto out;
- * index &= array->index_mask;
- * to avoid out-of-bounds cpu speculation
- */
- if (bpf_map_ptr_poisoned(aux)) {
- verbose(env, "tail_call abusing map_ptr\n");
- return -EINVAL;
- }
- map_ptr = BPF_MAP_PTR(aux->map_ptr_state);
- insn_buf[0] = BPF_JMP_IMM(BPF_JGE, BPF_REG_3,
- map_ptr->max_entries, 2);
- insn_buf[1] = BPF_ALU32_IMM(BPF_AND, BPF_REG_3,
- container_of(map_ptr,
- struct bpf_array,
- map)->index_mask);
- insn_buf[2] = *insn;
- cnt = 3;
- new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
- if (!new_prog)
- return -ENOMEM;
- delta += cnt - 1;
- env->prog = prog = new_prog;
- insn = new_prog->insnsi + i + delta;
- continue;
- }
- /* BPF_EMIT_CALL() assumptions in some of the map_gen_lookup
- * and other inlining handlers are currently limited to 64 bit
- * only.
- */
- if (prog->jit_requested && BITS_PER_LONG == 64 &&
- (insn->imm == BPF_FUNC_map_lookup_elem ||
- insn->imm == BPF_FUNC_map_update_elem ||
- insn->imm == BPF_FUNC_map_delete_elem ||
- insn->imm == BPF_FUNC_map_push_elem ||
- insn->imm == BPF_FUNC_map_pop_elem ||
- insn->imm == BPF_FUNC_map_peek_elem)) {
- aux = &env->insn_aux_data[i + delta];
- if (bpf_map_ptr_poisoned(aux))
- goto patch_call_imm;
- map_ptr = BPF_MAP_PTR(aux->map_ptr_state);
- ops = map_ptr->ops;
- if (insn->imm == BPF_FUNC_map_lookup_elem &&
- ops->map_gen_lookup) {
- cnt = ops->map_gen_lookup(map_ptr, insn_buf);
- if (cnt == -EOPNOTSUPP)
- goto patch_map_ops_generic;
- if (cnt <= 0 || cnt >= ARRAY_SIZE(insn_buf)) {
- verbose(env, "bpf verifier is misconfigured\n");
- return -EINVAL;
- }
- new_prog = bpf_patch_insn_data(env, i + delta,
- insn_buf, cnt);
- if (!new_prog)
- return -ENOMEM;
- delta += cnt - 1;
- env->prog = prog = new_prog;
- insn = new_prog->insnsi + i + delta;
- continue;
- }
- BUILD_BUG_ON(!__same_type(ops->map_lookup_elem,
- (void *(*)(struct bpf_map *map, void *key))NULL));
- BUILD_BUG_ON(!__same_type(ops->map_delete_elem,
- (int (*)(struct bpf_map *map, void *key))NULL));
- BUILD_BUG_ON(!__same_type(ops->map_update_elem,
- (int (*)(struct bpf_map *map, void *key, void *value,
- u64 flags))NULL));
- BUILD_BUG_ON(!__same_type(ops->map_push_elem,
- (int (*)(struct bpf_map *map, void *value,
- u64 flags))NULL));
- BUILD_BUG_ON(!__same_type(ops->map_pop_elem,
- (int (*)(struct bpf_map *map, void *value))NULL));
- BUILD_BUG_ON(!__same_type(ops->map_peek_elem,
- (int (*)(struct bpf_map *map, void *value))NULL));
- patch_map_ops_generic:
- switch (insn->imm) {
- case BPF_FUNC_map_lookup_elem:
- insn->imm = BPF_CAST_CALL(ops->map_lookup_elem) -
- __bpf_call_base;
- continue;
- case BPF_FUNC_map_update_elem:
- insn->imm = BPF_CAST_CALL(ops->map_update_elem) -
- __bpf_call_base;
- continue;
- case BPF_FUNC_map_delete_elem:
- insn->imm = BPF_CAST_CALL(ops->map_delete_elem) -
- __bpf_call_base;
- continue;
- case BPF_FUNC_map_push_elem:
- insn->imm = BPF_CAST_CALL(ops->map_push_elem) -
- __bpf_call_base;
- continue;
- case BPF_FUNC_map_pop_elem:
- insn->imm = BPF_CAST_CALL(ops->map_pop_elem) -
- __bpf_call_base;
- continue;
- case BPF_FUNC_map_peek_elem:
- insn->imm = BPF_CAST_CALL(ops->map_peek_elem) -
- __bpf_call_base;
- continue;
- }
- goto patch_call_imm;
- }
- if (prog->jit_requested && BITS_PER_LONG == 64 &&
- insn->imm == BPF_FUNC_jiffies64) {
- struct bpf_insn ld_jiffies_addr[2] = {
- BPF_LD_IMM64(BPF_REG_0,
- (unsigned long)&jiffies),
- };
- insn_buf[0] = ld_jiffies_addr[0];
- insn_buf[1] = ld_jiffies_addr[1];
- insn_buf[2] = BPF_LDX_MEM(BPF_DW, BPF_REG_0,
- BPF_REG_0, 0);
- cnt = 3;
- new_prog = bpf_patch_insn_data(env, i + delta, insn_buf,
- cnt);
- if (!new_prog)
- return -ENOMEM;
- delta += cnt - 1;
- env->prog = prog = new_prog;
- insn = new_prog->insnsi + i + delta;
- continue;
- }
- patch_call_imm:
- fn = env->ops->get_func_proto(insn->imm, env->prog);
- /* all functions that have prototype and verifier allowed
- * programs to call them, must be real in-kernel functions
- */
- if (!fn->func) {
- verbose(env,
- "kernel subsystem misconfigured func %s#%d\n",
- func_id_name(insn->imm), insn->imm);
- return -EFAULT;
- }
- insn->imm = fn->func - __bpf_call_base;
- }
- /* Since poke tab is now finalized, publish aux to tracker. */
- for (i = 0; i < prog->aux->size_poke_tab; i++) {
- map_ptr = prog->aux->poke_tab[i].tail_call.map;
- if (!map_ptr->ops->map_poke_track ||
- !map_ptr->ops->map_poke_untrack ||
- !map_ptr->ops->map_poke_run) {
- verbose(env, "bpf verifier is misconfigured\n");
- return -EINVAL;
- }
- ret = map_ptr->ops->map_poke_track(map_ptr, prog->aux);
- if (ret < 0) {
- verbose(env, "tracking tail call prog failed\n");
- return ret;
- }
- }
- return 0;
- }
- static void free_states(struct bpf_verifier_env *env)
- {
- struct bpf_verifier_state_list *sl, *sln;
- int i;
- sl = env->free_list;
- while (sl) {
- sln = sl->next;
- free_verifier_state(&sl->state, false);
- kfree(sl);
- sl = sln;
- }
- env->free_list = NULL;
- if (!env->explored_states)
- return;
- for (i = 0; i < state_htab_size(env); i++) {
- sl = env->explored_states[i];
- while (sl) {
- sln = sl->next;
- free_verifier_state(&sl->state, false);
- kfree(sl);
- sl = sln;
- }
- env->explored_states[i] = NULL;
- }
- }
- static int do_check_common(struct bpf_verifier_env *env, int subprog)
- {
- bool pop_log = !(env->log.level & BPF_LOG_LEVEL2);
- struct bpf_verifier_state *state;
- struct bpf_reg_state *regs;
- int ret, i;
- env->prev_linfo = NULL;
- env->pass_cnt++;
- state = kzalloc(sizeof(struct bpf_verifier_state), GFP_KERNEL);
- if (!state)
- return -ENOMEM;
- state->curframe = 0;
- state->speculative = false;
- state->branches = 1;
- state->frame[0] = kzalloc(sizeof(struct bpf_func_state), GFP_KERNEL);
- if (!state->frame[0]) {
- kfree(state);
- return -ENOMEM;
- }
- env->cur_state = state;
- init_func_state(env, state->frame[0],
- BPF_MAIN_FUNC /* callsite */,
- 0 /* frameno */,
- subprog);
- regs = state->frame[state->curframe]->regs;
- if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) {
- ret = btf_prepare_func_args(env, subprog, regs);
- if (ret)
- goto out;
- for (i = BPF_REG_1; i <= BPF_REG_5; i++) {
- if (regs[i].type == PTR_TO_CTX)
- mark_reg_known_zero(env, regs, i);
- else if (regs[i].type == SCALAR_VALUE)
- mark_reg_unknown(env, regs, i);
- }
- } else {
- /* 1st arg to a function */
- regs[BPF_REG_1].type = PTR_TO_CTX;
- mark_reg_known_zero(env, regs, BPF_REG_1);
- ret = btf_check_func_arg_match(env, subprog, regs);
- if (ret == -EFAULT)
- /* unlikely verifier bug. abort.
- * ret == 0 and ret < 0 are sadly acceptable for
- * main() function due to backward compatibility.
- * Like socket filter program may be written as:
- * int bpf_prog(struct pt_regs *ctx)
- * and never dereference that ctx in the program.
- * 'struct pt_regs' is a type mismatch for socket
- * filter that should be using 'struct __sk_buff'.
- */
- goto out;
- }
- ret = do_check(env);
- out:
- /* check for NULL is necessary, since cur_state can be freed inside
- * do_check() under memory pressure.
- */
- if (env->cur_state) {
- free_verifier_state(env->cur_state, true);
- env->cur_state = NULL;
- }
- while (!pop_stack(env, NULL, NULL, false));
- if (!ret && pop_log)
- bpf_vlog_reset(&env->log, 0);
- free_states(env);
- return ret;
- }
- /* Verify all global functions in a BPF program one by one based on their BTF.
- * All global functions must pass verification. Otherwise the whole program is rejected.
- * Consider:
- * int bar(int);
- * int foo(int f)
- * {
- * return bar(f);
- * }
- * int bar(int b)
- * {
- * ...
- * }
- * foo() will be verified first for R1=any_scalar_value. During verification it
- * will be assumed that bar() already verified successfully and call to bar()
- * from foo() will be checked for type match only. Later bar() will be verified
- * independently to check that it's safe for R1=any_scalar_value.
- */
- static int do_check_subprogs(struct bpf_verifier_env *env)
- {
- struct bpf_prog_aux *aux = env->prog->aux;
- int i, ret;
- if (!aux->func_info)
- return 0;
- for (i = 1; i < env->subprog_cnt; i++) {
- if (aux->func_info_aux[i].linkage != BTF_FUNC_GLOBAL)
- continue;
- env->insn_idx = env->subprog_info[i].start;
- WARN_ON_ONCE(env->insn_idx == 0);
- ret = do_check_common(env, i);
- if (ret) {
- return ret;
- } else if (env->log.level & BPF_LOG_LEVEL) {
- verbose(env,
- "Func#%d is safe for any args that match its prototype\n",
- i);
- }
- }
- return 0;
- }
- static int do_check_main(struct bpf_verifier_env *env)
- {
- int ret;
- env->insn_idx = 0;
- ret = do_check_common(env, 0);
- if (!ret)
- env->prog->aux->stack_depth = env->subprog_info[0].stack_depth;
- return ret;
- }
- static void print_verification_stats(struct bpf_verifier_env *env)
- {
- int i;
- if (env->log.level & BPF_LOG_STATS) {
- verbose(env, "verification time %lld usec\n",
- div_u64(env->verification_time, 1000));
- verbose(env, "stack depth ");
- for (i = 0; i < env->subprog_cnt; i++) {
- u32 depth = env->subprog_info[i].stack_depth;
- verbose(env, "%d", depth);
- if (i + 1 < env->subprog_cnt)
- verbose(env, "+");
- }
- verbose(env, "\n");
- }
- verbose(env, "processed %d insns (limit %d) max_states_per_insn %d "
- "total_states %d peak_states %d mark_read %d\n",
- env->insn_processed, BPF_COMPLEXITY_LIMIT_INSNS,
- env->max_states_per_insn, env->total_states,
- env->peak_states, env->longest_mark_read_walk);
- }
- static int check_struct_ops_btf_id(struct bpf_verifier_env *env)
- {
- const struct btf_type *t, *func_proto;
- const struct bpf_struct_ops *st_ops;
- const struct btf_member *member;
- struct bpf_prog *prog = env->prog;
- u32 btf_id, member_idx;
- const char *mname;
- if (!prog->gpl_compatible) {
- verbose(env, "struct ops programs must have a GPL compatible license\n");
- return -EINVAL;
- }
- btf_id = prog->aux->attach_btf_id;
- st_ops = bpf_struct_ops_find(btf_id);
- if (!st_ops) {
- verbose(env, "attach_btf_id %u is not a supported struct\n",
- btf_id);
- return -ENOTSUPP;
- }
- t = st_ops->type;
- member_idx = prog->expected_attach_type;
- if (member_idx >= btf_type_vlen(t)) {
- verbose(env, "attach to invalid member idx %u of struct %s\n",
- member_idx, st_ops->name);
- return -EINVAL;
- }
- member = &btf_type_member(t)[member_idx];
- mname = btf_name_by_offset(btf_vmlinux, member->name_off);
- func_proto = btf_type_resolve_func_ptr(btf_vmlinux, member->type,
- NULL);
- if (!func_proto) {
- verbose(env, "attach to invalid member %s(@idx %u) of struct %s\n",
- mname, member_idx, st_ops->name);
- return -EINVAL;
- }
- if (st_ops->check_member) {
- int err = st_ops->check_member(t, member);
- if (err) {
- verbose(env, "attach to unsupported member %s of struct %s\n",
- mname, st_ops->name);
- return err;
- }
- }
- prog->aux->attach_func_proto = func_proto;
- prog->aux->attach_func_name = mname;
- env->ops = st_ops->verifier_ops;
- return 0;
- }
- #define SECURITY_PREFIX "security_"
- static int check_attach_modify_return(unsigned long addr, const char *func_name)
- {
- if (within_error_injection_list(addr) ||
- !strncmp(SECURITY_PREFIX, func_name, sizeof(SECURITY_PREFIX) - 1))
- return 0;
- return -EINVAL;
- }
- /* non exhaustive list of sleepable bpf_lsm_*() functions */
- BTF_SET_START(btf_sleepable_lsm_hooks)
- #ifdef CONFIG_BPF_LSM
- BTF_ID(func, bpf_lsm_bprm_committed_creds)
- #else
- BTF_ID_UNUSED
- #endif
- BTF_SET_END(btf_sleepable_lsm_hooks)
- static int check_sleepable_lsm_hook(u32 btf_id)
- {
- return btf_id_set_contains(&btf_sleepable_lsm_hooks, btf_id);
- }
- /* list of non-sleepable functions that are otherwise on
- * ALLOW_ERROR_INJECTION list
- */
- BTF_SET_START(btf_non_sleepable_error_inject)
- /* Three functions below can be called from sleepable and non-sleepable context.
- * Assume non-sleepable from bpf safety point of view.
- */
- BTF_ID(func, __add_to_page_cache_locked)
- BTF_ID(func, should_fail_alloc_page)
- BTF_ID(func, should_failslab)
- BTF_SET_END(btf_non_sleepable_error_inject)
- static int check_non_sleepable_error_inject(u32 btf_id)
- {
- return btf_id_set_contains(&btf_non_sleepable_error_inject, btf_id);
- }
- int bpf_check_attach_target(struct bpf_verifier_log *log,
- const struct bpf_prog *prog,
- const struct bpf_prog *tgt_prog,
- u32 btf_id,
- struct bpf_attach_target_info *tgt_info)
- {
- bool prog_extension = prog->type == BPF_PROG_TYPE_EXT;
- const char prefix[] = "btf_trace_";
- int ret = 0, subprog = -1, i;
- const struct btf_type *t;
- bool conservative = true;
- const char *tname;
- struct btf *btf;
- long addr = 0;
- if (!btf_id) {
- bpf_log(log, "Tracing programs must provide btf_id\n");
- return -EINVAL;
- }
- btf = tgt_prog ? tgt_prog->aux->btf : btf_vmlinux;
- if (!btf) {
- bpf_log(log,
- "FENTRY/FEXIT program can only be attached to another program annotated with BTF\n");
- return -EINVAL;
- }
- t = btf_type_by_id(btf, btf_id);
- if (!t) {
- bpf_log(log, "attach_btf_id %u is invalid\n", btf_id);
- return -EINVAL;
- }
- tname = btf_name_by_offset(btf, t->name_off);
- if (!tname) {
- bpf_log(log, "attach_btf_id %u doesn't have a name\n", btf_id);
- return -EINVAL;
- }
- if (tgt_prog) {
- struct bpf_prog_aux *aux = tgt_prog->aux;
- for (i = 0; i < aux->func_info_cnt; i++)
- if (aux->func_info[i].type_id == btf_id) {
- subprog = i;
- break;
- }
- if (subprog == -1) {
- bpf_log(log, "Subprog %s doesn't exist\n", tname);
- return -EINVAL;
- }
- conservative = aux->func_info_aux[subprog].unreliable;
- if (prog_extension) {
- if (conservative) {
- bpf_log(log,
- "Cannot replace static functions\n");
- return -EINVAL;
- }
- if (!prog->jit_requested) {
- bpf_log(log,
- "Extension programs should be JITed\n");
- return -EINVAL;
- }
- }
- if (!tgt_prog->jited) {
- bpf_log(log, "Can attach to only JITed progs\n");
- return -EINVAL;
- }
- if (tgt_prog->type == prog->type) {
- /* Cannot fentry/fexit another fentry/fexit program.
- * Cannot attach program extension to another extension.
- * It's ok to attach fentry/fexit to extension program.
- */
- bpf_log(log, "Cannot recursively attach\n");
- return -EINVAL;
- }
- if (tgt_prog->type == BPF_PROG_TYPE_TRACING &&
- prog_extension &&
- (tgt_prog->expected_attach_type == BPF_TRACE_FENTRY ||
- tgt_prog->expected_attach_type == BPF_TRACE_FEXIT)) {
- /* Program extensions can extend all program types
- * except fentry/fexit. The reason is the following.
- * The fentry/fexit programs are used for performance
- * analysis, stats and can be attached to any program
- * type except themselves. When extension program is
- * replacing XDP function it is necessary to allow
- * performance analysis of all functions. Both original
- * XDP program and its program extension. Hence
- * attaching fentry/fexit to BPF_PROG_TYPE_EXT is
- * allowed. If extending of fentry/fexit was allowed it
- * would be possible to create long call chain
- * fentry->extension->fentry->extension beyond
- * reasonable stack size. Hence extending fentry is not
- * allowed.
- */
- bpf_log(log, "Cannot extend fentry/fexit\n");
- return -EINVAL;
- }
- } else {
- if (prog_extension) {
- bpf_log(log, "Cannot replace kernel functions\n");
- return -EINVAL;
- }
- }
- switch (prog->expected_attach_type) {
- case BPF_TRACE_RAW_TP:
- if (tgt_prog) {
- bpf_log(log,
- "Only FENTRY/FEXIT progs are attachable to another BPF prog\n");
- return -EINVAL;
- }
- if (!btf_type_is_typedef(t)) {
- bpf_log(log, "attach_btf_id %u is not a typedef\n",
- btf_id);
- return -EINVAL;
- }
- if (strncmp(prefix, tname, sizeof(prefix) - 1)) {
- bpf_log(log, "attach_btf_id %u points to wrong type name %s\n",
- btf_id, tname);
- return -EINVAL;
- }
- tname += sizeof(prefix) - 1;
- t = btf_type_by_id(btf, t->type);
- if (!btf_type_is_ptr(t))
- /* should never happen in valid vmlinux build */
- return -EINVAL;
- t = btf_type_by_id(btf, t->type);
- if (!btf_type_is_func_proto(t))
- /* should never happen in valid vmlinux build */
- return -EINVAL;
- break;
- case BPF_TRACE_ITER:
- if (!btf_type_is_func(t)) {
- bpf_log(log, "attach_btf_id %u is not a function\n",
- btf_id);
- return -EINVAL;
- }
- t = btf_type_by_id(btf, t->type);
- if (!btf_type_is_func_proto(t))
- return -EINVAL;
- ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel);
- if (ret)
- return ret;
- break;
- default:
- if (!prog_extension)
- return -EINVAL;
- fallthrough;
- case BPF_MODIFY_RETURN:
- case BPF_LSM_MAC:
- case BPF_TRACE_FENTRY:
- case BPF_TRACE_FEXIT:
- if (!btf_type_is_func(t)) {
- bpf_log(log, "attach_btf_id %u is not a function\n",
- btf_id);
- return -EINVAL;
- }
- if (prog_extension &&
- btf_check_type_match(log, prog, btf, t))
- return -EINVAL;
- t = btf_type_by_id(btf, t->type);
- if (!btf_type_is_func_proto(t))
- return -EINVAL;
- if ((prog->aux->saved_dst_prog_type || prog->aux->saved_dst_attach_type) &&
- (!tgt_prog || prog->aux->saved_dst_prog_type != tgt_prog->type ||
- prog->aux->saved_dst_attach_type != tgt_prog->expected_attach_type))
- return -EINVAL;
- if (tgt_prog && conservative)
- t = NULL;
- ret = btf_distill_func_proto(log, btf, t, tname, &tgt_info->fmodel);
- if (ret < 0)
- return ret;
- if (tgt_prog) {
- if (subprog == 0)
- addr = (long) tgt_prog->bpf_func;
- else
- addr = (long) tgt_prog->aux->func[subprog]->bpf_func;
- } else {
- addr = kallsyms_lookup_name(tname);
- if (!addr) {
- bpf_log(log,
- "The address of function %s cannot be found\n",
- tname);
- return -ENOENT;
- }
- }
- if (prog->aux->sleepable) {
- ret = -EINVAL;
- switch (prog->type) {
- case BPF_PROG_TYPE_TRACING:
- /* fentry/fexit/fmod_ret progs can be sleepable only if they are
- * attached to ALLOW_ERROR_INJECTION and are not in denylist.
- */
- if (!check_non_sleepable_error_inject(btf_id) &&
- within_error_injection_list(addr))
- ret = 0;
- break;
- case BPF_PROG_TYPE_LSM:
- /* LSM progs check that they are attached to bpf_lsm_*() funcs.
- * Only some of them are sleepable.
- */
- if (check_sleepable_lsm_hook(btf_id))
- ret = 0;
- break;
- default:
- break;
- }
- if (ret) {
- bpf_log(log, "%s is not sleepable\n", tname);
- return ret;
- }
- } else if (prog->expected_attach_type == BPF_MODIFY_RETURN) {
- if (tgt_prog) {
- bpf_log(log, "can't modify return codes of BPF programs\n");
- return -EINVAL;
- }
- ret = check_attach_modify_return(addr, tname);
- if (ret) {
- bpf_log(log, "%s() is not modifiable\n", tname);
- return ret;
- }
- }
- break;
- }
- tgt_info->tgt_addr = addr;
- tgt_info->tgt_name = tname;
- tgt_info->tgt_type = t;
- return 0;
- }
- static int check_attach_btf_id(struct bpf_verifier_env *env)
- {
- struct bpf_prog *prog = env->prog;
- struct bpf_prog *tgt_prog = prog->aux->dst_prog;
- struct bpf_attach_target_info tgt_info = {};
- u32 btf_id = prog->aux->attach_btf_id;
- struct bpf_trampoline *tr;
- int ret;
- u64 key;
- if (prog->aux->sleepable && prog->type != BPF_PROG_TYPE_TRACING &&
- prog->type != BPF_PROG_TYPE_LSM) {
- verbose(env, "Only fentry/fexit/fmod_ret and lsm programs can be sleepable\n");
- return -EINVAL;
- }
- if (prog->type == BPF_PROG_TYPE_STRUCT_OPS)
- return check_struct_ops_btf_id(env);
- if (prog->type != BPF_PROG_TYPE_TRACING &&
- prog->type != BPF_PROG_TYPE_LSM &&
- prog->type != BPF_PROG_TYPE_EXT)
- return 0;
- ret = bpf_check_attach_target(&env->log, prog, tgt_prog, btf_id, &tgt_info);
- if (ret)
- return ret;
- if (tgt_prog && prog->type == BPF_PROG_TYPE_EXT) {
- /* to make freplace equivalent to their targets, they need to
- * inherit env->ops and expected_attach_type for the rest of the
- * verification
- */
- env->ops = bpf_verifier_ops[tgt_prog->type];
- prog->expected_attach_type = tgt_prog->expected_attach_type;
- }
- /* store info about the attachment target that will be used later */
- prog->aux->attach_func_proto = tgt_info.tgt_type;
- prog->aux->attach_func_name = tgt_info.tgt_name;
- if (tgt_prog) {
- prog->aux->saved_dst_prog_type = tgt_prog->type;
- prog->aux->saved_dst_attach_type = tgt_prog->expected_attach_type;
- }
- if (prog->expected_attach_type == BPF_TRACE_RAW_TP) {
- prog->aux->attach_btf_trace = true;
- return 0;
- } else if (prog->expected_attach_type == BPF_TRACE_ITER) {
- if (!bpf_iter_prog_supported(prog))
- return -EINVAL;
- return 0;
- }
- if (prog->type == BPF_PROG_TYPE_LSM) {
- ret = bpf_lsm_verify_prog(&env->log, prog);
- if (ret < 0)
- return ret;
- }
- key = bpf_trampoline_compute_key(tgt_prog, btf_id);
- tr = bpf_trampoline_get(key, &tgt_info);
- if (!tr)
- return -ENOMEM;
- prog->aux->dst_trampoline = tr;
- return 0;
- }
- struct btf *bpf_get_btf_vmlinux(void)
- {
- if (!btf_vmlinux && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
- mutex_lock(&bpf_verifier_lock);
- if (!btf_vmlinux)
- btf_vmlinux = btf_parse_vmlinux();
- mutex_unlock(&bpf_verifier_lock);
- }
- return btf_vmlinux;
- }
- int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
- union bpf_attr __user *uattr)
- {
- u64 start_time = ktime_get_ns();
- struct bpf_verifier_env *env;
- struct bpf_verifier_log *log;
- int i, len, ret = -EINVAL;
- bool is_priv;
- /* no program is valid */
- if (ARRAY_SIZE(bpf_verifier_ops) == 0)
- return -EINVAL;
- /* 'struct bpf_verifier_env' can be global, but since it's not small,
- * allocate/free it every time bpf_check() is called
- */
- env = kzalloc(sizeof(struct bpf_verifier_env), GFP_KERNEL);
- if (!env)
- return -ENOMEM;
- log = &env->log;
- len = (*prog)->len;
- env->insn_aux_data =
- vzalloc(array_size(sizeof(struct bpf_insn_aux_data), len));
- ret = -ENOMEM;
- if (!env->insn_aux_data)
- goto err_free_env;
- for (i = 0; i < len; i++)
- env->insn_aux_data[i].orig_idx = i;
- env->prog = *prog;
- env->ops = bpf_verifier_ops[env->prog->type];
- is_priv = bpf_capable();
- bpf_get_btf_vmlinux();
- /* grab the mutex to protect few globals used by verifier */
- if (!is_priv)
- mutex_lock(&bpf_verifier_lock);
- if (attr->log_level || attr->log_buf || attr->log_size) {
- /* user requested verbose verifier output
- * and supplied buffer to store the verification trace
- */
- log->level = attr->log_level;
- log->ubuf = (char __user *) (unsigned long) attr->log_buf;
- log->len_total = attr->log_size;
- /* log attributes have to be sane */
- if (!bpf_verifier_log_attr_valid(log)) {
- ret = -EINVAL;
- goto err_unlock;
- }
- }
- if (IS_ERR(btf_vmlinux)) {
- /* Either gcc or pahole or kernel are broken. */
- verbose(env, "in-kernel BTF is malformed\n");
- ret = PTR_ERR(btf_vmlinux);
- goto skip_full_check;
- }
- env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
- if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
- env->strict_alignment = true;
- if (attr->prog_flags & BPF_F_ANY_ALIGNMENT)
- env->strict_alignment = false;
- env->allow_ptr_leaks = bpf_allow_ptr_leaks();
- env->allow_uninit_stack = bpf_allow_uninit_stack();
- env->allow_ptr_to_map_access = bpf_allow_ptr_to_map_access();
- env->bypass_spec_v1 = bpf_bypass_spec_v1();
- env->bypass_spec_v4 = bpf_bypass_spec_v4();
- env->bpf_capable = bpf_capable();
- if (is_priv)
- env->test_state_freq = attr->prog_flags & BPF_F_TEST_STATE_FREQ;
- env->explored_states = kvcalloc(state_htab_size(env),
- sizeof(struct bpf_verifier_state_list *),
- GFP_USER);
- ret = -ENOMEM;
- if (!env->explored_states)
- goto skip_full_check;
- ret = check_subprogs(env);
- if (ret < 0)
- goto skip_full_check;
- ret = check_btf_info(env, attr, uattr);
- if (ret < 0)
- goto skip_full_check;
- ret = check_attach_btf_id(env);
- if (ret)
- goto skip_full_check;
- ret = resolve_pseudo_ldimm64(env);
- if (ret < 0)
- goto skip_full_check;
- if (bpf_prog_is_dev_bound(env->prog->aux)) {
- ret = bpf_prog_offload_verifier_prep(env->prog);
- if (ret)
- goto skip_full_check;
- }
- ret = check_cfg(env);
- if (ret < 0)
- goto skip_full_check;
- ret = do_check_subprogs(env);
- ret = ret ?: do_check_main(env);
- if (ret == 0 && bpf_prog_is_dev_bound(env->prog->aux))
- ret = bpf_prog_offload_finalize(env);
- skip_full_check:
- kvfree(env->explored_states);
- if (ret == 0)
- ret = check_max_stack_depth(env);
- /* instruction rewrites happen after this point */
- if (is_priv) {
- if (ret == 0)
- opt_hard_wire_dead_code_branches(env);
- if (ret == 0)
- ret = opt_remove_dead_code(env);
- if (ret == 0)
- ret = opt_remove_nops(env);
- } else {
- if (ret == 0)
- sanitize_dead_code(env);
- }
- if (ret == 0)
- /* program is valid, convert *(u32*)(ctx + off) accesses */
- ret = convert_ctx_accesses(env);
- if (ret == 0)
- ret = fixup_bpf_calls(env);
- /* do 32-bit optimization after insn patching has done so those patched
- * insns could be handled correctly.
- */
- if (ret == 0 && !bpf_prog_is_dev_bound(env->prog->aux)) {
- ret = opt_subreg_zext_lo32_rnd_hi32(env, attr);
- env->prog->aux->verifier_zext = bpf_jit_needs_zext() ? !ret
- : false;
- }
- if (ret == 0)
- ret = fixup_call_args(env);
- env->verification_time = ktime_get_ns() - start_time;
- print_verification_stats(env);
- if (log->level && bpf_verifier_log_full(log))
- ret = -ENOSPC;
- if (log->level && !log->ubuf) {
- ret = -EFAULT;
- goto err_release_maps;
- }
- if (ret == 0 && env->used_map_cnt) {
- /* if program passed verifier, update used_maps in bpf_prog_info */
- env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
- sizeof(env->used_maps[0]),
- GFP_KERNEL);
- if (!env->prog->aux->used_maps) {
- ret = -ENOMEM;
- goto err_release_maps;
- }
- memcpy(env->prog->aux->used_maps, env->used_maps,
- sizeof(env->used_maps[0]) * env->used_map_cnt);
- env->prog->aux->used_map_cnt = env->used_map_cnt;
- /* program is valid. Convert pseudo bpf_ld_imm64 into generic
- * bpf_ld_imm64 instructions
- */
- convert_pseudo_ld_imm64(env);
- }
- if (ret == 0)
- adjust_btf_func(env);
- err_release_maps:
- if (!env->prog->aux->used_maps)
- /* if we didn't copy map pointers into bpf_prog_info, release
- * them now. Otherwise free_used_maps() will release them.
- */
- release_maps(env);
- /* extension progs temporarily inherit the attach_type of their targets
- for verification purposes, so set it back to zero before returning
- */
- if (env->prog->type == BPF_PROG_TYPE_EXT)
- env->prog->expected_attach_type = 0;
- *prog = env->prog;
- err_unlock:
- if (!is_priv)
- mutex_unlock(&bpf_verifier_lock);
- vfree(env->insn_aux_data);
- err_free_env:
- kfree(env);
- return ret;
- }
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