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- // SPDX-License-Identifier: GPL-2.0
- /*
- * linux/kernel/seccomp.c
- *
- * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com>
- *
- * Copyright (C) 2012 Google, Inc.
- * Will Drewry <wad@chromium.org>
- *
- * This defines a simple but solid secure-computing facility.
- *
- * Mode 1 uses a fixed list of allowed system calls.
- * Mode 2 allows user-defined system call filters in the form
- * of Berkeley Packet Filters/Linux Socket Filters.
- */
- #define pr_fmt(fmt) "seccomp: " fmt
- #include <linux/refcount.h>
- #include <linux/audit.h>
- #include <linux/compat.h>
- #include <linux/coredump.h>
- #include <linux/kmemleak.h>
- #include <linux/nospec.h>
- #include <linux/prctl.h>
- #include <linux/sched.h>
- #include <linux/sched/task_stack.h>
- #include <linux/seccomp.h>
- #include <linux/slab.h>
- #include <linux/syscalls.h>
- #include <linux/sysctl.h>
- #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
- #include <asm/syscall.h>
- #endif
- #ifdef CONFIG_SECCOMP_FILTER
- #include <linux/file.h>
- #include <linux/filter.h>
- #include <linux/pid.h>
- #include <linux/ptrace.h>
- #include <linux/capability.h>
- #include <linux/tracehook.h>
- #include <linux/uaccess.h>
- #include <linux/anon_inodes.h>
- #include <linux/lockdep.h>
- /*
- * When SECCOMP_IOCTL_NOTIF_ID_VALID was first introduced, it had the
- * wrong direction flag in the ioctl number. This is the broken one,
- * which the kernel needs to keep supporting until all userspaces stop
- * using the wrong command number.
- */
- #define SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR SECCOMP_IOR(2, __u64)
- enum notify_state {
- SECCOMP_NOTIFY_INIT,
- SECCOMP_NOTIFY_SENT,
- SECCOMP_NOTIFY_REPLIED,
- };
- struct seccomp_knotif {
- /* The struct pid of the task whose filter triggered the notification */
- struct task_struct *task;
- /* The "cookie" for this request; this is unique for this filter. */
- u64 id;
- /*
- * The seccomp data. This pointer is valid the entire time this
- * notification is active, since it comes from __seccomp_filter which
- * eclipses the entire lifecycle here.
- */
- const struct seccomp_data *data;
- /*
- * Notification states. When SECCOMP_RET_USER_NOTIF is returned, a
- * struct seccomp_knotif is created and starts out in INIT. Once the
- * handler reads the notification off of an FD, it transitions to SENT.
- * If a signal is received the state transitions back to INIT and
- * another message is sent. When the userspace handler replies, state
- * transitions to REPLIED.
- */
- enum notify_state state;
- /* The return values, only valid when in SECCOMP_NOTIFY_REPLIED */
- int error;
- long val;
- u32 flags;
- /*
- * Signals when this has changed states, such as the listener
- * dying, a new seccomp addfd message, or changing to REPLIED
- */
- struct completion ready;
- struct list_head list;
- /* outstanding addfd requests */
- struct list_head addfd;
- };
- /**
- * struct seccomp_kaddfd - container for seccomp_addfd ioctl messages
- *
- * @file: A reference to the file to install in the other task
- * @fd: The fd number to install it at. If the fd number is -1, it means the
- * installing process should allocate the fd as normal.
- * @flags: The flags for the new file descriptor. At the moment, only O_CLOEXEC
- * is allowed.
- * @ret: The return value of the installing process. It is set to the fd num
- * upon success (>= 0).
- * @completion: Indicates that the installing process has completed fd
- * installation, or gone away (either due to successful
- * reply, or signal)
- *
- */
- struct seccomp_kaddfd {
- struct file *file;
- int fd;
- unsigned int flags;
- /* To only be set on reply */
- int ret;
- struct completion completion;
- struct list_head list;
- };
- /**
- * struct notification - container for seccomp userspace notifications. Since
- * most seccomp filters will not have notification listeners attached and this
- * structure is fairly large, we store the notification-specific stuff in a
- * separate structure.
- *
- * @request: A semaphore that users of this notification can wait on for
- * changes. Actual reads and writes are still controlled with
- * filter->notify_lock.
- * @next_id: The id of the next request.
- * @notifications: A list of struct seccomp_knotif elements.
- */
- struct notification {
- struct semaphore request;
- u64 next_id;
- struct list_head notifications;
- };
- #ifdef SECCOMP_ARCH_NATIVE
- /**
- * struct action_cache - per-filter cache of seccomp actions per
- * arch/syscall pair
- *
- * @allow_native: A bitmap where each bit represents whether the
- * filter will always allow the syscall, for the
- * native architecture.
- * @allow_compat: A bitmap where each bit represents whether the
- * filter will always allow the syscall, for the
- * compat architecture.
- */
- struct action_cache {
- DECLARE_BITMAP(allow_native, SECCOMP_ARCH_NATIVE_NR);
- #ifdef SECCOMP_ARCH_COMPAT
- DECLARE_BITMAP(allow_compat, SECCOMP_ARCH_COMPAT_NR);
- #endif
- };
- #else
- struct action_cache { };
- static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
- const struct seccomp_data *sd)
- {
- return false;
- }
- static inline void seccomp_cache_prepare(struct seccomp_filter *sfilter)
- {
- }
- #endif /* SECCOMP_ARCH_NATIVE */
- /**
- * struct seccomp_filter - container for seccomp BPF programs
- *
- * @refs: Reference count to manage the object lifetime.
- * A filter's reference count is incremented for each directly
- * attached task, once for the dependent filter, and if
- * requested for the user notifier. When @refs reaches zero,
- * the filter can be freed.
- * @users: A filter's @users count is incremented for each directly
- * attached task (filter installation, fork(), thread_sync),
- * and once for the dependent filter (tracked in filter->prev).
- * When it reaches zero it indicates that no direct or indirect
- * users of that filter exist. No new tasks can get associated with
- * this filter after reaching 0. The @users count is always smaller
- * or equal to @refs. Hence, reaching 0 for @users does not mean
- * the filter can be freed.
- * @cache: cache of arch/syscall mappings to actions
- * @log: true if all actions except for SECCOMP_RET_ALLOW should be logged
- * @prev: points to a previously installed, or inherited, filter
- * @prog: the BPF program to evaluate
- * @notif: the struct that holds all notification related information
- * @notify_lock: A lock for all notification-related accesses.
- * @wqh: A wait queue for poll if a notifier is in use.
- *
- * seccomp_filter objects are organized in a tree linked via the @prev
- * pointer. For any task, it appears to be a singly-linked list starting
- * with current->seccomp.filter, the most recently attached or inherited filter.
- * However, multiple filters may share a @prev node, by way of fork(), which
- * results in a unidirectional tree existing in memory. This is similar to
- * how namespaces work.
- *
- * seccomp_filter objects should never be modified after being attached
- * to a task_struct (other than @refs).
- */
- struct seccomp_filter {
- refcount_t refs;
- refcount_t users;
- bool log;
- struct action_cache cache;
- struct seccomp_filter *prev;
- struct bpf_prog *prog;
- struct notification *notif;
- struct mutex notify_lock;
- wait_queue_head_t wqh;
- };
- /* Limit any path through the tree to 256KB worth of instructions. */
- #define MAX_INSNS_PER_PATH ((1 << 18) / sizeof(struct sock_filter))
- /*
- * Endianness is explicitly ignored and left for BPF program authors to manage
- * as per the specific architecture.
- */
- static void populate_seccomp_data(struct seccomp_data *sd)
- {
- /*
- * Instead of using current_pt_reg(), we're already doing the work
- * to safely fetch "current", so just use "task" everywhere below.
- */
- struct task_struct *task = current;
- struct pt_regs *regs = task_pt_regs(task);
- unsigned long args[6];
- sd->nr = syscall_get_nr(task, regs);
- sd->arch = syscall_get_arch(task);
- syscall_get_arguments(task, regs, args);
- sd->args[0] = args[0];
- sd->args[1] = args[1];
- sd->args[2] = args[2];
- sd->args[3] = args[3];
- sd->args[4] = args[4];
- sd->args[5] = args[5];
- sd->instruction_pointer = KSTK_EIP(task);
- }
- /**
- * seccomp_check_filter - verify seccomp filter code
- * @filter: filter to verify
- * @flen: length of filter
- *
- * Takes a previously checked filter (by bpf_check_classic) and
- * redirects all filter code that loads struct sk_buff data
- * and related data through seccomp_bpf_load. It also
- * enforces length and alignment checking of those loads.
- *
- * Returns 0 if the rule set is legal or -EINVAL if not.
- */
- static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
- {
- int pc;
- for (pc = 0; pc < flen; pc++) {
- struct sock_filter *ftest = &filter[pc];
- u16 code = ftest->code;
- u32 k = ftest->k;
- switch (code) {
- case BPF_LD | BPF_W | BPF_ABS:
- ftest->code = BPF_LDX | BPF_W | BPF_ABS;
- /* 32-bit aligned and not out of bounds. */
- if (k >= sizeof(struct seccomp_data) || k & 3)
- return -EINVAL;
- continue;
- case BPF_LD | BPF_W | BPF_LEN:
- ftest->code = BPF_LD | BPF_IMM;
- ftest->k = sizeof(struct seccomp_data);
- continue;
- case BPF_LDX | BPF_W | BPF_LEN:
- ftest->code = BPF_LDX | BPF_IMM;
- ftest->k = sizeof(struct seccomp_data);
- continue;
- /* Explicitly include allowed calls. */
- case BPF_RET | BPF_K:
- case BPF_RET | BPF_A:
- case BPF_ALU | BPF_ADD | BPF_K:
- case BPF_ALU | BPF_ADD | BPF_X:
- case BPF_ALU | BPF_SUB | BPF_K:
- case BPF_ALU | BPF_SUB | BPF_X:
- case BPF_ALU | BPF_MUL | BPF_K:
- case BPF_ALU | BPF_MUL | BPF_X:
- case BPF_ALU | BPF_DIV | BPF_K:
- case BPF_ALU | BPF_DIV | BPF_X:
- case BPF_ALU | BPF_AND | BPF_K:
- case BPF_ALU | BPF_AND | BPF_X:
- case BPF_ALU | BPF_OR | BPF_K:
- case BPF_ALU | BPF_OR | BPF_X:
- case BPF_ALU | BPF_XOR | BPF_K:
- case BPF_ALU | BPF_XOR | BPF_X:
- case BPF_ALU | BPF_LSH | BPF_K:
- case BPF_ALU | BPF_LSH | BPF_X:
- case BPF_ALU | BPF_RSH | BPF_K:
- case BPF_ALU | BPF_RSH | BPF_X:
- case BPF_ALU | BPF_NEG:
- case BPF_LD | BPF_IMM:
- case BPF_LDX | BPF_IMM:
- case BPF_MISC | BPF_TAX:
- case BPF_MISC | BPF_TXA:
- case BPF_LD | BPF_MEM:
- case BPF_LDX | BPF_MEM:
- case BPF_ST:
- case BPF_STX:
- case BPF_JMP | BPF_JA:
- case BPF_JMP | BPF_JEQ | BPF_K:
- case BPF_JMP | BPF_JEQ | BPF_X:
- case BPF_JMP | BPF_JGE | BPF_K:
- case BPF_JMP | BPF_JGE | BPF_X:
- case BPF_JMP | BPF_JGT | BPF_K:
- case BPF_JMP | BPF_JGT | BPF_X:
- case BPF_JMP | BPF_JSET | BPF_K:
- case BPF_JMP | BPF_JSET | BPF_X:
- continue;
- default:
- return -EINVAL;
- }
- }
- return 0;
- }
- #ifdef SECCOMP_ARCH_NATIVE
- static inline bool seccomp_cache_check_allow_bitmap(const void *bitmap,
- size_t bitmap_size,
- int syscall_nr)
- {
- if (unlikely(syscall_nr < 0 || syscall_nr >= bitmap_size))
- return false;
- syscall_nr = array_index_nospec(syscall_nr, bitmap_size);
- return test_bit(syscall_nr, bitmap);
- }
- /**
- * seccomp_cache_check_allow - lookup seccomp cache
- * @sfilter: The seccomp filter
- * @sd: The seccomp data to lookup the cache with
- *
- * Returns true if the seccomp_data is cached and allowed.
- */
- static inline bool seccomp_cache_check_allow(const struct seccomp_filter *sfilter,
- const struct seccomp_data *sd)
- {
- int syscall_nr = sd->nr;
- const struct action_cache *cache = &sfilter->cache;
- #ifndef SECCOMP_ARCH_COMPAT
- /* A native-only architecture doesn't need to check sd->arch. */
- return seccomp_cache_check_allow_bitmap(cache->allow_native,
- SECCOMP_ARCH_NATIVE_NR,
- syscall_nr);
- #else
- if (likely(sd->arch == SECCOMP_ARCH_NATIVE))
- return seccomp_cache_check_allow_bitmap(cache->allow_native,
- SECCOMP_ARCH_NATIVE_NR,
- syscall_nr);
- if (likely(sd->arch == SECCOMP_ARCH_COMPAT))
- return seccomp_cache_check_allow_bitmap(cache->allow_compat,
- SECCOMP_ARCH_COMPAT_NR,
- syscall_nr);
- #endif /* SECCOMP_ARCH_COMPAT */
- WARN_ON_ONCE(true);
- return false;
- }
- #endif /* SECCOMP_ARCH_NATIVE */
- /**
- * seccomp_run_filters - evaluates all seccomp filters against @sd
- * @sd: optional seccomp data to be passed to filters
- * @match: stores struct seccomp_filter that resulted in the return value,
- * unless filter returned SECCOMP_RET_ALLOW, in which case it will
- * be unchanged.
- *
- * Returns valid seccomp BPF response codes.
- */
- #define ACTION_ONLY(ret) ((s32)((ret) & (SECCOMP_RET_ACTION_FULL)))
- static u32 seccomp_run_filters(const struct seccomp_data *sd,
- struct seccomp_filter **match)
- {
- u32 ret = SECCOMP_RET_ALLOW;
- /* Make sure cross-thread synced filter points somewhere sane. */
- struct seccomp_filter *f =
- READ_ONCE(current->seccomp.filter);
- /* Ensure unexpected behavior doesn't result in failing open. */
- if (WARN_ON(f == NULL))
- return SECCOMP_RET_KILL_PROCESS;
- if (seccomp_cache_check_allow(f, sd))
- return SECCOMP_RET_ALLOW;
- /*
- * All filters in the list are evaluated and the lowest BPF return
- * value always takes priority (ignoring the DATA).
- */
- for (; f; f = f->prev) {
- u32 cur_ret = bpf_prog_run_pin_on_cpu(f->prog, sd);
- if (ACTION_ONLY(cur_ret) < ACTION_ONLY(ret)) {
- ret = cur_ret;
- *match = f;
- }
- }
- return ret;
- }
- #endif /* CONFIG_SECCOMP_FILTER */
- static inline bool seccomp_may_assign_mode(unsigned long seccomp_mode)
- {
- assert_spin_locked(¤t->sighand->siglock);
- if (current->seccomp.mode && current->seccomp.mode != seccomp_mode)
- return false;
- return true;
- }
- void __weak arch_seccomp_spec_mitigate(struct task_struct *task) { }
- static inline void seccomp_assign_mode(struct task_struct *task,
- unsigned long seccomp_mode,
- unsigned long flags)
- {
- assert_spin_locked(&task->sighand->siglock);
- task->seccomp.mode = seccomp_mode;
- /*
- * Make sure TIF_SECCOMP cannot be set before the mode (and
- * filter) is set.
- */
- smp_mb__before_atomic();
- /* Assume default seccomp processes want spec flaw mitigation. */
- if ((flags & SECCOMP_FILTER_FLAG_SPEC_ALLOW) == 0)
- arch_seccomp_spec_mitigate(task);
- set_tsk_thread_flag(task, TIF_SECCOMP);
- }
- #ifdef CONFIG_SECCOMP_FILTER
- /* Returns 1 if the parent is an ancestor of the child. */
- static int is_ancestor(struct seccomp_filter *parent,
- struct seccomp_filter *child)
- {
- /* NULL is the root ancestor. */
- if (parent == NULL)
- return 1;
- for (; child; child = child->prev)
- if (child == parent)
- return 1;
- return 0;
- }
- /**
- * seccomp_can_sync_threads: checks if all threads can be synchronized
- *
- * Expects sighand and cred_guard_mutex locks to be held.
- *
- * Returns 0 on success, -ve on error, or the pid of a thread which was
- * either not in the correct seccomp mode or did not have an ancestral
- * seccomp filter.
- */
- static inline pid_t seccomp_can_sync_threads(void)
- {
- struct task_struct *thread, *caller;
- BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
- assert_spin_locked(¤t->sighand->siglock);
- /* Validate all threads being eligible for synchronization. */
- caller = current;
- for_each_thread(caller, thread) {
- pid_t failed;
- /* Skip current, since it is initiating the sync. */
- if (thread == caller)
- continue;
- if (thread->seccomp.mode == SECCOMP_MODE_DISABLED ||
- (thread->seccomp.mode == SECCOMP_MODE_FILTER &&
- is_ancestor(thread->seccomp.filter,
- caller->seccomp.filter)))
- continue;
- /* Return the first thread that cannot be synchronized. */
- failed = task_pid_vnr(thread);
- /* If the pid cannot be resolved, then return -ESRCH */
- if (WARN_ON(failed == 0))
- failed = -ESRCH;
- return failed;
- }
- return 0;
- }
- static inline void seccomp_filter_free(struct seccomp_filter *filter)
- {
- if (filter) {
- bpf_prog_destroy(filter->prog);
- kfree(filter);
- }
- }
- static void __seccomp_filter_orphan(struct seccomp_filter *orig)
- {
- while (orig && refcount_dec_and_test(&orig->users)) {
- if (waitqueue_active(&orig->wqh))
- wake_up_poll(&orig->wqh, EPOLLHUP);
- orig = orig->prev;
- }
- }
- static void __put_seccomp_filter(struct seccomp_filter *orig)
- {
- /* Clean up single-reference branches iteratively. */
- while (orig && refcount_dec_and_test(&orig->refs)) {
- struct seccomp_filter *freeme = orig;
- orig = orig->prev;
- seccomp_filter_free(freeme);
- }
- }
- static void __seccomp_filter_release(struct seccomp_filter *orig)
- {
- /* Notify about any unused filters in the task's former filter tree. */
- __seccomp_filter_orphan(orig);
- /* Finally drop all references to the task's former tree. */
- __put_seccomp_filter(orig);
- }
- /**
- * seccomp_filter_release - Detach the task from its filter tree,
- * drop its reference count, and notify
- * about unused filters
- *
- * This function should only be called when the task is exiting as
- * it detaches it from its filter tree. As such, READ_ONCE() and
- * barriers are not needed here, as would normally be needed.
- */
- void seccomp_filter_release(struct task_struct *tsk)
- {
- struct seccomp_filter *orig = tsk->seccomp.filter;
- /* Detach task from its filter tree. */
- tsk->seccomp.filter = NULL;
- __seccomp_filter_release(orig);
- }
- /**
- * seccomp_sync_threads: sets all threads to use current's filter
- *
- * Expects sighand and cred_guard_mutex locks to be held, and for
- * seccomp_can_sync_threads() to have returned success already
- * without dropping the locks.
- *
- */
- static inline void seccomp_sync_threads(unsigned long flags)
- {
- struct task_struct *thread, *caller;
- BUG_ON(!mutex_is_locked(¤t->signal->cred_guard_mutex));
- assert_spin_locked(¤t->sighand->siglock);
- /* Synchronize all threads. */
- caller = current;
- for_each_thread(caller, thread) {
- /* Skip current, since it needs no changes. */
- if (thread == caller)
- continue;
- /* Get a task reference for the new leaf node. */
- get_seccomp_filter(caller);
- /*
- * Drop the task reference to the shared ancestor since
- * current's path will hold a reference. (This also
- * allows a put before the assignment.)
- */
- __seccomp_filter_release(thread->seccomp.filter);
- /* Make our new filter tree visible. */
- smp_store_release(&thread->seccomp.filter,
- caller->seccomp.filter);
- atomic_set(&thread->seccomp.filter_count,
- atomic_read(&caller->seccomp.filter_count));
- /*
- * Don't let an unprivileged task work around
- * the no_new_privs restriction by creating
- * a thread that sets it up, enters seccomp,
- * then dies.
- */
- if (task_no_new_privs(caller))
- task_set_no_new_privs(thread);
- /*
- * Opt the other thread into seccomp if needed.
- * As threads are considered to be trust-realm
- * equivalent (see ptrace_may_access), it is safe to
- * allow one thread to transition the other.
- */
- if (thread->seccomp.mode == SECCOMP_MODE_DISABLED)
- seccomp_assign_mode(thread, SECCOMP_MODE_FILTER,
- flags);
- }
- }
- /**
- * seccomp_prepare_filter: Prepares a seccomp filter for use.
- * @fprog: BPF program to install
- *
- * Returns filter on success or an ERR_PTR on failure.
- */
- static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
- {
- struct seccomp_filter *sfilter;
- int ret;
- const bool save_orig =
- #if defined(CONFIG_CHECKPOINT_RESTORE) || defined(SECCOMP_ARCH_NATIVE)
- true;
- #else
- false;
- #endif
- if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
- return ERR_PTR(-EINVAL);
- BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
- /*
- * Installing a seccomp filter requires that the task has
- * CAP_SYS_ADMIN in its namespace or be running with no_new_privs.
- * This avoids scenarios where unprivileged tasks can affect the
- * behavior of privileged children.
- */
- if (!task_no_new_privs(current) &&
- !ns_capable_noaudit(current_user_ns(), CAP_SYS_ADMIN))
- return ERR_PTR(-EACCES);
- /* Allocate a new seccomp_filter */
- sfilter = kzalloc(sizeof(*sfilter), GFP_KERNEL | __GFP_NOWARN);
- if (!sfilter)
- return ERR_PTR(-ENOMEM);
- mutex_init(&sfilter->notify_lock);
- ret = bpf_prog_create_from_user(&sfilter->prog, fprog,
- seccomp_check_filter, save_orig);
- if (ret < 0) {
- kfree(sfilter);
- return ERR_PTR(ret);
- }
- refcount_set(&sfilter->refs, 1);
- refcount_set(&sfilter->users, 1);
- init_waitqueue_head(&sfilter->wqh);
- return sfilter;
- }
- /**
- * seccomp_prepare_user_filter - prepares a user-supplied sock_fprog
- * @user_filter: pointer to the user data containing a sock_fprog.
- *
- * Returns 0 on success and non-zero otherwise.
- */
- static struct seccomp_filter *
- seccomp_prepare_user_filter(const char __user *user_filter)
- {
- struct sock_fprog fprog;
- struct seccomp_filter *filter = ERR_PTR(-EFAULT);
- #ifdef CONFIG_COMPAT
- if (in_compat_syscall()) {
- struct compat_sock_fprog fprog32;
- if (copy_from_user(&fprog32, user_filter, sizeof(fprog32)))
- goto out;
- fprog.len = fprog32.len;
- fprog.filter = compat_ptr(fprog32.filter);
- } else /* falls through to the if below. */
- #endif
- if (copy_from_user(&fprog, user_filter, sizeof(fprog)))
- goto out;
- filter = seccomp_prepare_filter(&fprog);
- out:
- return filter;
- }
- #ifdef SECCOMP_ARCH_NATIVE
- /**
- * seccomp_is_const_allow - check if filter is constant allow with given data
- * @fprog: The BPF programs
- * @sd: The seccomp data to check against, only syscall number and arch
- * number are considered constant.
- */
- static bool seccomp_is_const_allow(struct sock_fprog_kern *fprog,
- struct seccomp_data *sd)
- {
- unsigned int reg_value = 0;
- unsigned int pc;
- bool op_res;
- if (WARN_ON_ONCE(!fprog))
- return false;
- for (pc = 0; pc < fprog->len; pc++) {
- struct sock_filter *insn = &fprog->filter[pc];
- u16 code = insn->code;
- u32 k = insn->k;
- switch (code) {
- case BPF_LD | BPF_W | BPF_ABS:
- switch (k) {
- case offsetof(struct seccomp_data, nr):
- reg_value = sd->nr;
- break;
- case offsetof(struct seccomp_data, arch):
- reg_value = sd->arch;
- break;
- default:
- /* can't optimize (non-constant value load) */
- return false;
- }
- break;
- case BPF_RET | BPF_K:
- /* reached return with constant values only, check allow */
- return k == SECCOMP_RET_ALLOW;
- case BPF_JMP | BPF_JA:
- pc += insn->k;
- break;
- case BPF_JMP | BPF_JEQ | BPF_K:
- case BPF_JMP | BPF_JGE | BPF_K:
- case BPF_JMP | BPF_JGT | BPF_K:
- case BPF_JMP | BPF_JSET | BPF_K:
- switch (BPF_OP(code)) {
- case BPF_JEQ:
- op_res = reg_value == k;
- break;
- case BPF_JGE:
- op_res = reg_value >= k;
- break;
- case BPF_JGT:
- op_res = reg_value > k;
- break;
- case BPF_JSET:
- op_res = !!(reg_value & k);
- break;
- default:
- /* can't optimize (unknown jump) */
- return false;
- }
- pc += op_res ? insn->jt : insn->jf;
- break;
- case BPF_ALU | BPF_AND | BPF_K:
- reg_value &= k;
- break;
- default:
- /* can't optimize (unknown insn) */
- return false;
- }
- }
- /* ran off the end of the filter?! */
- WARN_ON(1);
- return false;
- }
- static void seccomp_cache_prepare_bitmap(struct seccomp_filter *sfilter,
- void *bitmap, const void *bitmap_prev,
- size_t bitmap_size, int arch)
- {
- struct sock_fprog_kern *fprog = sfilter->prog->orig_prog;
- struct seccomp_data sd;
- int nr;
- if (bitmap_prev) {
- /* The new filter must be as restrictive as the last. */
- bitmap_copy(bitmap, bitmap_prev, bitmap_size);
- } else {
- /* Before any filters, all syscalls are always allowed. */
- bitmap_fill(bitmap, bitmap_size);
- }
- for (nr = 0; nr < bitmap_size; nr++) {
- /* No bitmap change: not a cacheable action. */
- if (!test_bit(nr, bitmap))
- continue;
- sd.nr = nr;
- sd.arch = arch;
- /* No bitmap change: continue to always allow. */
- if (seccomp_is_const_allow(fprog, &sd))
- continue;
- /*
- * Not a cacheable action: always run filters.
- * atomic clear_bit() not needed, filter not visible yet.
- */
- __clear_bit(nr, bitmap);
- }
- }
- /**
- * seccomp_cache_prepare - emulate the filter to find cachable syscalls
- * @sfilter: The seccomp filter
- *
- * Returns 0 if successful or -errno if error occurred.
- */
- static void seccomp_cache_prepare(struct seccomp_filter *sfilter)
- {
- struct action_cache *cache = &sfilter->cache;
- const struct action_cache *cache_prev =
- sfilter->prev ? &sfilter->prev->cache : NULL;
- seccomp_cache_prepare_bitmap(sfilter, cache->allow_native,
- cache_prev ? cache_prev->allow_native : NULL,
- SECCOMP_ARCH_NATIVE_NR,
- SECCOMP_ARCH_NATIVE);
- #ifdef SECCOMP_ARCH_COMPAT
- seccomp_cache_prepare_bitmap(sfilter, cache->allow_compat,
- cache_prev ? cache_prev->allow_compat : NULL,
- SECCOMP_ARCH_COMPAT_NR,
- SECCOMP_ARCH_COMPAT);
- #endif /* SECCOMP_ARCH_COMPAT */
- }
- #endif /* SECCOMP_ARCH_NATIVE */
- /**
- * seccomp_attach_filter: validate and attach filter
- * @flags: flags to change filter behavior
- * @filter: seccomp filter to add to the current process
- *
- * Caller must be holding current->sighand->siglock lock.
- *
- * Returns 0 on success, -ve on error, or
- * - in TSYNC mode: the pid of a thread which was either not in the correct
- * seccomp mode or did not have an ancestral seccomp filter
- * - in NEW_LISTENER mode: the fd of the new listener
- */
- static long seccomp_attach_filter(unsigned int flags,
- struct seccomp_filter *filter)
- {
- unsigned long total_insns;
- struct seccomp_filter *walker;
- assert_spin_locked(¤t->sighand->siglock);
- /* Validate resulting filter length. */
- total_insns = filter->prog->len;
- for (walker = current->seccomp.filter; walker; walker = walker->prev)
- total_insns += walker->prog->len + 4; /* 4 instr penalty */
- if (total_insns > MAX_INSNS_PER_PATH)
- return -ENOMEM;
- /* If thread sync has been requested, check that it is possible. */
- if (flags & SECCOMP_FILTER_FLAG_TSYNC) {
- int ret;
- ret = seccomp_can_sync_threads();
- if (ret) {
- if (flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
- return -ESRCH;
- else
- return ret;
- }
- }
- /* Set log flag, if present. */
- if (flags & SECCOMP_FILTER_FLAG_LOG)
- filter->log = true;
- /*
- * If there is an existing filter, make it the prev and don't drop its
- * task reference.
- */
- filter->prev = current->seccomp.filter;
- seccomp_cache_prepare(filter);
- current->seccomp.filter = filter;
- atomic_inc(¤t->seccomp.filter_count);
- /* Now that the new filter is in place, synchronize to all threads. */
- if (flags & SECCOMP_FILTER_FLAG_TSYNC)
- seccomp_sync_threads(flags);
- return 0;
- }
- static void __get_seccomp_filter(struct seccomp_filter *filter)
- {
- refcount_inc(&filter->refs);
- }
- /* get_seccomp_filter - increments the reference count of the filter on @tsk */
- void get_seccomp_filter(struct task_struct *tsk)
- {
- struct seccomp_filter *orig = tsk->seccomp.filter;
- if (!orig)
- return;
- __get_seccomp_filter(orig);
- refcount_inc(&orig->users);
- }
- static void seccomp_init_siginfo(kernel_siginfo_t *info, int syscall, int reason)
- {
- clear_siginfo(info);
- info->si_signo = SIGSYS;
- info->si_code = SYS_SECCOMP;
- info->si_call_addr = (void __user *)KSTK_EIP(current);
- info->si_errno = reason;
- info->si_arch = syscall_get_arch(current);
- info->si_syscall = syscall;
- }
- /**
- * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
- * @syscall: syscall number to send to userland
- * @reason: filter-supplied reason code to send to userland (via si_errno)
- *
- * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
- */
- static void seccomp_send_sigsys(int syscall, int reason)
- {
- struct kernel_siginfo info;
- seccomp_init_siginfo(&info, syscall, reason);
- force_sig_info(&info);
- }
- #endif /* CONFIG_SECCOMP_FILTER */
- /* For use with seccomp_actions_logged */
- #define SECCOMP_LOG_KILL_PROCESS (1 << 0)
- #define SECCOMP_LOG_KILL_THREAD (1 << 1)
- #define SECCOMP_LOG_TRAP (1 << 2)
- #define SECCOMP_LOG_ERRNO (1 << 3)
- #define SECCOMP_LOG_TRACE (1 << 4)
- #define SECCOMP_LOG_LOG (1 << 5)
- #define SECCOMP_LOG_ALLOW (1 << 6)
- #define SECCOMP_LOG_USER_NOTIF (1 << 7)
- static u32 seccomp_actions_logged = SECCOMP_LOG_KILL_PROCESS |
- SECCOMP_LOG_KILL_THREAD |
- SECCOMP_LOG_TRAP |
- SECCOMP_LOG_ERRNO |
- SECCOMP_LOG_USER_NOTIF |
- SECCOMP_LOG_TRACE |
- SECCOMP_LOG_LOG;
- static inline void seccomp_log(unsigned long syscall, long signr, u32 action,
- bool requested)
- {
- bool log = false;
- switch (action) {
- case SECCOMP_RET_ALLOW:
- break;
- case SECCOMP_RET_TRAP:
- log = requested && seccomp_actions_logged & SECCOMP_LOG_TRAP;
- break;
- case SECCOMP_RET_ERRNO:
- log = requested && seccomp_actions_logged & SECCOMP_LOG_ERRNO;
- break;
- case SECCOMP_RET_TRACE:
- log = requested && seccomp_actions_logged & SECCOMP_LOG_TRACE;
- break;
- case SECCOMP_RET_USER_NOTIF:
- log = requested && seccomp_actions_logged & SECCOMP_LOG_USER_NOTIF;
- break;
- case SECCOMP_RET_LOG:
- log = seccomp_actions_logged & SECCOMP_LOG_LOG;
- break;
- case SECCOMP_RET_KILL_THREAD:
- log = seccomp_actions_logged & SECCOMP_LOG_KILL_THREAD;
- break;
- case SECCOMP_RET_KILL_PROCESS:
- default:
- log = seccomp_actions_logged & SECCOMP_LOG_KILL_PROCESS;
- }
- /*
- * Emit an audit message when the action is RET_KILL_*, RET_LOG, or the
- * FILTER_FLAG_LOG bit was set. The admin has the ability to silence
- * any action from being logged by removing the action name from the
- * seccomp_actions_logged sysctl.
- */
- if (!log)
- return;
- audit_seccomp(syscall, signr, action);
- }
- /*
- * Secure computing mode 1 allows only read/write/exit/sigreturn.
- * To be fully secure this must be combined with rlimit
- * to limit the stack allocations too.
- */
- static const int mode1_syscalls[] = {
- __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn,
- -1, /* negative terminated */
- };
- static void __secure_computing_strict(int this_syscall)
- {
- const int *allowed_syscalls = mode1_syscalls;
- #ifdef CONFIG_COMPAT
- if (in_compat_syscall())
- allowed_syscalls = get_compat_mode1_syscalls();
- #endif
- do {
- if (*allowed_syscalls == this_syscall)
- return;
- } while (*++allowed_syscalls != -1);
- #ifdef SECCOMP_DEBUG
- dump_stack();
- #endif
- seccomp_log(this_syscall, SIGKILL, SECCOMP_RET_KILL_THREAD, true);
- do_exit(SIGKILL);
- }
- #ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
- void secure_computing_strict(int this_syscall)
- {
- int mode = current->seccomp.mode;
- if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
- unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
- return;
- if (mode == SECCOMP_MODE_DISABLED)
- return;
- else if (mode == SECCOMP_MODE_STRICT)
- __secure_computing_strict(this_syscall);
- else
- BUG();
- }
- #else
- #ifdef CONFIG_SECCOMP_FILTER
- static u64 seccomp_next_notify_id(struct seccomp_filter *filter)
- {
- /*
- * Note: overflow is ok here, the id just needs to be unique per
- * filter.
- */
- lockdep_assert_held(&filter->notify_lock);
- return filter->notif->next_id++;
- }
- static void seccomp_handle_addfd(struct seccomp_kaddfd *addfd)
- {
- /*
- * Remove the notification, and reset the list pointers, indicating
- * that it has been handled.
- */
- list_del_init(&addfd->list);
- addfd->ret = receive_fd_replace(addfd->fd, addfd->file, addfd->flags);
- complete(&addfd->completion);
- }
- static int seccomp_do_user_notification(int this_syscall,
- struct seccomp_filter *match,
- const struct seccomp_data *sd)
- {
- int err;
- u32 flags = 0;
- long ret = 0;
- struct seccomp_knotif n = {};
- struct seccomp_kaddfd *addfd, *tmp;
- mutex_lock(&match->notify_lock);
- err = -ENOSYS;
- if (!match->notif)
- goto out;
- n.task = current;
- n.state = SECCOMP_NOTIFY_INIT;
- n.data = sd;
- n.id = seccomp_next_notify_id(match);
- init_completion(&n.ready);
- list_add(&n.list, &match->notif->notifications);
- INIT_LIST_HEAD(&n.addfd);
- up(&match->notif->request);
- wake_up_poll(&match->wqh, EPOLLIN | EPOLLRDNORM);
- /*
- * This is where we wait for a reply from userspace.
- */
- do {
- mutex_unlock(&match->notify_lock);
- err = wait_for_completion_interruptible(&n.ready);
- mutex_lock(&match->notify_lock);
- if (err != 0)
- goto interrupted;
- addfd = list_first_entry_or_null(&n.addfd,
- struct seccomp_kaddfd, list);
- /* Check if we were woken up by a addfd message */
- if (addfd)
- seccomp_handle_addfd(addfd);
- } while (n.state != SECCOMP_NOTIFY_REPLIED);
- ret = n.val;
- err = n.error;
- flags = n.flags;
- interrupted:
- /* If there were any pending addfd calls, clear them out */
- list_for_each_entry_safe(addfd, tmp, &n.addfd, list) {
- /* The process went away before we got a chance to handle it */
- addfd->ret = -ESRCH;
- list_del_init(&addfd->list);
- complete(&addfd->completion);
- }
- /*
- * Note that it's possible the listener died in between the time when
- * we were notified of a response (or a signal) and when we were able to
- * re-acquire the lock, so only delete from the list if the
- * notification actually exists.
- *
- * Also note that this test is only valid because there's no way to
- * *reattach* to a notifier right now. If one is added, we'll need to
- * keep track of the notif itself and make sure they match here.
- */
- if (match->notif)
- list_del(&n.list);
- out:
- mutex_unlock(&match->notify_lock);
- /* Userspace requests to continue the syscall. */
- if (flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE)
- return 0;
- syscall_set_return_value(current, current_pt_regs(),
- err, ret);
- return -1;
- }
- static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
- const bool recheck_after_trace)
- {
- u32 filter_ret, action;
- struct seccomp_filter *match = NULL;
- int data;
- struct seccomp_data sd_local;
- /*
- * Make sure that any changes to mode from another thread have
- * been seen after TIF_SECCOMP was seen.
- */
- rmb();
- if (!sd) {
- populate_seccomp_data(&sd_local);
- sd = &sd_local;
- }
- filter_ret = seccomp_run_filters(sd, &match);
- data = filter_ret & SECCOMP_RET_DATA;
- action = filter_ret & SECCOMP_RET_ACTION_FULL;
- switch (action) {
- case SECCOMP_RET_ERRNO:
- /* Set low-order bits as an errno, capped at MAX_ERRNO. */
- if (data > MAX_ERRNO)
- data = MAX_ERRNO;
- syscall_set_return_value(current, current_pt_regs(),
- -data, 0);
- goto skip;
- case SECCOMP_RET_TRAP:
- /* Show the handler the original registers. */
- syscall_rollback(current, current_pt_regs());
- /* Let the filter pass back 16 bits of data. */
- seccomp_send_sigsys(this_syscall, data);
- goto skip;
- case SECCOMP_RET_TRACE:
- /* We've been put in this state by the ptracer already. */
- if (recheck_after_trace)
- return 0;
- /* ENOSYS these calls if there is no tracer attached. */
- if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
- syscall_set_return_value(current,
- current_pt_regs(),
- -ENOSYS, 0);
- goto skip;
- }
- /* Allow the BPF to provide the event message */
- ptrace_event(PTRACE_EVENT_SECCOMP, data);
- /*
- * The delivery of a fatal signal during event
- * notification may silently skip tracer notification,
- * which could leave us with a potentially unmodified
- * syscall that the tracer would have liked to have
- * changed. Since the process is about to die, we just
- * force the syscall to be skipped and let the signal
- * kill the process and correctly handle any tracer exit
- * notifications.
- */
- if (fatal_signal_pending(current))
- goto skip;
- /* Check if the tracer forced the syscall to be skipped. */
- this_syscall = syscall_get_nr(current, current_pt_regs());
- if (this_syscall < 0)
- goto skip;
- /*
- * Recheck the syscall, since it may have changed. This
- * intentionally uses a NULL struct seccomp_data to force
- * a reload of all registers. This does not goto skip since
- * a skip would have already been reported.
- */
- if (__seccomp_filter(this_syscall, NULL, true))
- return -1;
- return 0;
- case SECCOMP_RET_USER_NOTIF:
- if (seccomp_do_user_notification(this_syscall, match, sd))
- goto skip;
- return 0;
- case SECCOMP_RET_LOG:
- seccomp_log(this_syscall, 0, action, true);
- return 0;
- case SECCOMP_RET_ALLOW:
- /*
- * Note that the "match" filter will always be NULL for
- * this action since SECCOMP_RET_ALLOW is the starting
- * state in seccomp_run_filters().
- */
- return 0;
- case SECCOMP_RET_KILL_THREAD:
- case SECCOMP_RET_KILL_PROCESS:
- default:
- seccomp_log(this_syscall, SIGSYS, action, true);
- /* Dump core only if this is the last remaining thread. */
- if (action != SECCOMP_RET_KILL_THREAD ||
- get_nr_threads(current) == 1) {
- kernel_siginfo_t info;
- /* Show the original registers in the dump. */
- syscall_rollback(current, current_pt_regs());
- /* Trigger a manual coredump since do_exit skips it. */
- seccomp_init_siginfo(&info, this_syscall, data);
- do_coredump(&info);
- }
- if (action == SECCOMP_RET_KILL_THREAD)
- do_exit(SIGSYS);
- else
- do_group_exit(SIGSYS);
- }
- unreachable();
- skip:
- seccomp_log(this_syscall, 0, action, match ? match->log : false);
- return -1;
- }
- #else
- static int __seccomp_filter(int this_syscall, const struct seccomp_data *sd,
- const bool recheck_after_trace)
- {
- BUG();
- return -1;
- }
- #endif
- int __secure_computing(const struct seccomp_data *sd)
- {
- int mode = current->seccomp.mode;
- int this_syscall;
- if (IS_ENABLED(CONFIG_CHECKPOINT_RESTORE) &&
- unlikely(current->ptrace & PT_SUSPEND_SECCOMP))
- return 0;
- this_syscall = sd ? sd->nr :
- syscall_get_nr(current, current_pt_regs());
- switch (mode) {
- case SECCOMP_MODE_STRICT:
- __secure_computing_strict(this_syscall); /* may call do_exit */
- return 0;
- case SECCOMP_MODE_FILTER:
- return __seccomp_filter(this_syscall, sd, false);
- default:
- BUG();
- }
- }
- #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
- long prctl_get_seccomp(void)
- {
- return current->seccomp.mode;
- }
- /**
- * seccomp_set_mode_strict: internal function for setting strict seccomp
- *
- * Once current->seccomp.mode is non-zero, it may not be changed.
- *
- * Returns 0 on success or -EINVAL on failure.
- */
- static long seccomp_set_mode_strict(void)
- {
- const unsigned long seccomp_mode = SECCOMP_MODE_STRICT;
- long ret = -EINVAL;
- spin_lock_irq(¤t->sighand->siglock);
- if (!seccomp_may_assign_mode(seccomp_mode))
- goto out;
- #ifdef TIF_NOTSC
- disable_TSC();
- #endif
- seccomp_assign_mode(current, seccomp_mode, 0);
- ret = 0;
- out:
- spin_unlock_irq(¤t->sighand->siglock);
- return ret;
- }
- #ifdef CONFIG_SECCOMP_FILTER
- static void seccomp_notify_free(struct seccomp_filter *filter)
- {
- kfree(filter->notif);
- filter->notif = NULL;
- }
- static void seccomp_notify_detach(struct seccomp_filter *filter)
- {
- struct seccomp_knotif *knotif;
- if (!filter)
- return;
- mutex_lock(&filter->notify_lock);
- /*
- * If this file is being closed because e.g. the task who owned it
- * died, let's wake everyone up who was waiting on us.
- */
- list_for_each_entry(knotif, &filter->notif->notifications, list) {
- if (knotif->state == SECCOMP_NOTIFY_REPLIED)
- continue;
- knotif->state = SECCOMP_NOTIFY_REPLIED;
- knotif->error = -ENOSYS;
- knotif->val = 0;
- /*
- * We do not need to wake up any pending addfd messages, as
- * the notifier will do that for us, as this just looks
- * like a standard reply.
- */
- complete(&knotif->ready);
- }
- seccomp_notify_free(filter);
- mutex_unlock(&filter->notify_lock);
- }
- static int seccomp_notify_release(struct inode *inode, struct file *file)
- {
- struct seccomp_filter *filter = file->private_data;
- seccomp_notify_detach(filter);
- __put_seccomp_filter(filter);
- return 0;
- }
- /* must be called with notif_lock held */
- static inline struct seccomp_knotif *
- find_notification(struct seccomp_filter *filter, u64 id)
- {
- struct seccomp_knotif *cur;
- lockdep_assert_held(&filter->notify_lock);
- list_for_each_entry(cur, &filter->notif->notifications, list) {
- if (cur->id == id)
- return cur;
- }
- return NULL;
- }
- static long seccomp_notify_recv(struct seccomp_filter *filter,
- void __user *buf)
- {
- struct seccomp_knotif *knotif = NULL, *cur;
- struct seccomp_notif unotif;
- ssize_t ret;
- /* Verify that we're not given garbage to keep struct extensible. */
- ret = check_zeroed_user(buf, sizeof(unotif));
- if (ret < 0)
- return ret;
- if (!ret)
- return -EINVAL;
- memset(&unotif, 0, sizeof(unotif));
- ret = down_interruptible(&filter->notif->request);
- if (ret < 0)
- return ret;
- mutex_lock(&filter->notify_lock);
- list_for_each_entry(cur, &filter->notif->notifications, list) {
- if (cur->state == SECCOMP_NOTIFY_INIT) {
- knotif = cur;
- break;
- }
- }
- /*
- * If we didn't find a notification, it could be that the task was
- * interrupted by a fatal signal between the time we were woken and
- * when we were able to acquire the rw lock.
- */
- if (!knotif) {
- ret = -ENOENT;
- goto out;
- }
- unotif.id = knotif->id;
- unotif.pid = task_pid_vnr(knotif->task);
- unotif.data = *(knotif->data);
- knotif->state = SECCOMP_NOTIFY_SENT;
- wake_up_poll(&filter->wqh, EPOLLOUT | EPOLLWRNORM);
- ret = 0;
- out:
- mutex_unlock(&filter->notify_lock);
- if (ret == 0 && copy_to_user(buf, &unotif, sizeof(unotif))) {
- ret = -EFAULT;
- /*
- * Userspace screwed up. To make sure that we keep this
- * notification alive, let's reset it back to INIT. It
- * may have died when we released the lock, so we need to make
- * sure it's still around.
- */
- mutex_lock(&filter->notify_lock);
- knotif = find_notification(filter, unotif.id);
- if (knotif) {
- knotif->state = SECCOMP_NOTIFY_INIT;
- up(&filter->notif->request);
- }
- mutex_unlock(&filter->notify_lock);
- }
- return ret;
- }
- static long seccomp_notify_send(struct seccomp_filter *filter,
- void __user *buf)
- {
- struct seccomp_notif_resp resp = {};
- struct seccomp_knotif *knotif;
- long ret;
- if (copy_from_user(&resp, buf, sizeof(resp)))
- return -EFAULT;
- if (resp.flags & ~SECCOMP_USER_NOTIF_FLAG_CONTINUE)
- return -EINVAL;
- if ((resp.flags & SECCOMP_USER_NOTIF_FLAG_CONTINUE) &&
- (resp.error || resp.val))
- return -EINVAL;
- ret = mutex_lock_interruptible(&filter->notify_lock);
- if (ret < 0)
- return ret;
- knotif = find_notification(filter, resp.id);
- if (!knotif) {
- ret = -ENOENT;
- goto out;
- }
- /* Allow exactly one reply. */
- if (knotif->state != SECCOMP_NOTIFY_SENT) {
- ret = -EINPROGRESS;
- goto out;
- }
- ret = 0;
- knotif->state = SECCOMP_NOTIFY_REPLIED;
- knotif->error = resp.error;
- knotif->val = resp.val;
- knotif->flags = resp.flags;
- complete(&knotif->ready);
- out:
- mutex_unlock(&filter->notify_lock);
- return ret;
- }
- static long seccomp_notify_id_valid(struct seccomp_filter *filter,
- void __user *buf)
- {
- struct seccomp_knotif *knotif;
- u64 id;
- long ret;
- if (copy_from_user(&id, buf, sizeof(id)))
- return -EFAULT;
- ret = mutex_lock_interruptible(&filter->notify_lock);
- if (ret < 0)
- return ret;
- knotif = find_notification(filter, id);
- if (knotif && knotif->state == SECCOMP_NOTIFY_SENT)
- ret = 0;
- else
- ret = -ENOENT;
- mutex_unlock(&filter->notify_lock);
- return ret;
- }
- static long seccomp_notify_addfd(struct seccomp_filter *filter,
- struct seccomp_notif_addfd __user *uaddfd,
- unsigned int size)
- {
- struct seccomp_notif_addfd addfd;
- struct seccomp_knotif *knotif;
- struct seccomp_kaddfd kaddfd;
- int ret;
- BUILD_BUG_ON(sizeof(addfd) < SECCOMP_NOTIFY_ADDFD_SIZE_VER0);
- BUILD_BUG_ON(sizeof(addfd) != SECCOMP_NOTIFY_ADDFD_SIZE_LATEST);
- if (size < SECCOMP_NOTIFY_ADDFD_SIZE_VER0 || size >= PAGE_SIZE)
- return -EINVAL;
- ret = copy_struct_from_user(&addfd, sizeof(addfd), uaddfd, size);
- if (ret)
- return ret;
- if (addfd.newfd_flags & ~O_CLOEXEC)
- return -EINVAL;
- if (addfd.flags & ~SECCOMP_ADDFD_FLAG_SETFD)
- return -EINVAL;
- if (addfd.newfd && !(addfd.flags & SECCOMP_ADDFD_FLAG_SETFD))
- return -EINVAL;
- kaddfd.file = fget(addfd.srcfd);
- if (!kaddfd.file)
- return -EBADF;
- kaddfd.flags = addfd.newfd_flags;
- kaddfd.fd = (addfd.flags & SECCOMP_ADDFD_FLAG_SETFD) ?
- addfd.newfd : -1;
- init_completion(&kaddfd.completion);
- ret = mutex_lock_interruptible(&filter->notify_lock);
- if (ret < 0)
- goto out;
- knotif = find_notification(filter, addfd.id);
- if (!knotif) {
- ret = -ENOENT;
- goto out_unlock;
- }
- /*
- * We do not want to allow for FD injection to occur before the
- * notification has been picked up by a userspace handler, or after
- * the notification has been replied to.
- */
- if (knotif->state != SECCOMP_NOTIFY_SENT) {
- ret = -EINPROGRESS;
- goto out_unlock;
- }
- list_add(&kaddfd.list, &knotif->addfd);
- complete(&knotif->ready);
- mutex_unlock(&filter->notify_lock);
- /* Now we wait for it to be processed or be interrupted */
- ret = wait_for_completion_interruptible(&kaddfd.completion);
- if (ret == 0) {
- /*
- * We had a successful completion. The other side has already
- * removed us from the addfd queue, and
- * wait_for_completion_interruptible has a memory barrier upon
- * success that lets us read this value directly without
- * locking.
- */
- ret = kaddfd.ret;
- goto out;
- }
- mutex_lock(&filter->notify_lock);
- /*
- * Even though we were woken up by a signal and not a successful
- * completion, a completion may have happened in the mean time.
- *
- * We need to check again if the addfd request has been handled,
- * and if not, we will remove it from the queue.
- */
- if (list_empty(&kaddfd.list))
- ret = kaddfd.ret;
- else
- list_del(&kaddfd.list);
- out_unlock:
- mutex_unlock(&filter->notify_lock);
- out:
- fput(kaddfd.file);
- return ret;
- }
- static long seccomp_notify_ioctl(struct file *file, unsigned int cmd,
- unsigned long arg)
- {
- struct seccomp_filter *filter = file->private_data;
- void __user *buf = (void __user *)arg;
- /* Fixed-size ioctls */
- switch (cmd) {
- case SECCOMP_IOCTL_NOTIF_RECV:
- return seccomp_notify_recv(filter, buf);
- case SECCOMP_IOCTL_NOTIF_SEND:
- return seccomp_notify_send(filter, buf);
- case SECCOMP_IOCTL_NOTIF_ID_VALID_WRONG_DIR:
- case SECCOMP_IOCTL_NOTIF_ID_VALID:
- return seccomp_notify_id_valid(filter, buf);
- }
- /* Extensible Argument ioctls */
- #define EA_IOCTL(cmd) ((cmd) & ~(IOC_INOUT | IOCSIZE_MASK))
- switch (EA_IOCTL(cmd)) {
- case EA_IOCTL(SECCOMP_IOCTL_NOTIF_ADDFD):
- return seccomp_notify_addfd(filter, buf, _IOC_SIZE(cmd));
- default:
- return -EINVAL;
- }
- }
- static __poll_t seccomp_notify_poll(struct file *file,
- struct poll_table_struct *poll_tab)
- {
- struct seccomp_filter *filter = file->private_data;
- __poll_t ret = 0;
- struct seccomp_knotif *cur;
- poll_wait(file, &filter->wqh, poll_tab);
- if (mutex_lock_interruptible(&filter->notify_lock) < 0)
- return EPOLLERR;
- list_for_each_entry(cur, &filter->notif->notifications, list) {
- if (cur->state == SECCOMP_NOTIFY_INIT)
- ret |= EPOLLIN | EPOLLRDNORM;
- if (cur->state == SECCOMP_NOTIFY_SENT)
- ret |= EPOLLOUT | EPOLLWRNORM;
- if ((ret & EPOLLIN) && (ret & EPOLLOUT))
- break;
- }
- mutex_unlock(&filter->notify_lock);
- if (refcount_read(&filter->users) == 0)
- ret |= EPOLLHUP;
- return ret;
- }
- static const struct file_operations seccomp_notify_ops = {
- .poll = seccomp_notify_poll,
- .release = seccomp_notify_release,
- .unlocked_ioctl = seccomp_notify_ioctl,
- .compat_ioctl = seccomp_notify_ioctl,
- };
- static struct file *init_listener(struct seccomp_filter *filter)
- {
- struct file *ret;
- ret = ERR_PTR(-ENOMEM);
- filter->notif = kzalloc(sizeof(*(filter->notif)), GFP_KERNEL);
- if (!filter->notif)
- goto out;
- sema_init(&filter->notif->request, 0);
- filter->notif->next_id = get_random_u64();
- INIT_LIST_HEAD(&filter->notif->notifications);
- ret = anon_inode_getfile("seccomp notify", &seccomp_notify_ops,
- filter, O_RDWR);
- if (IS_ERR(ret))
- goto out_notif;
- /* The file has a reference to it now */
- __get_seccomp_filter(filter);
- out_notif:
- if (IS_ERR(ret))
- seccomp_notify_free(filter);
- out:
- return ret;
- }
- /*
- * Does @new_child have a listener while an ancestor also has a listener?
- * If so, we'll want to reject this filter.
- * This only has to be tested for the current process, even in the TSYNC case,
- * because TSYNC installs @child with the same parent on all threads.
- * Note that @new_child is not hooked up to its parent at this point yet, so
- * we use current->seccomp.filter.
- */
- static bool has_duplicate_listener(struct seccomp_filter *new_child)
- {
- struct seccomp_filter *cur;
- /* must be protected against concurrent TSYNC */
- lockdep_assert_held(¤t->sighand->siglock);
- if (!new_child->notif)
- return false;
- for (cur = current->seccomp.filter; cur; cur = cur->prev) {
- if (cur->notif)
- return true;
- }
- return false;
- }
- /**
- * seccomp_set_mode_filter: internal function for setting seccomp filter
- * @flags: flags to change filter behavior
- * @filter: struct sock_fprog containing filter
- *
- * This function may be called repeatedly to install additional filters.
- * Every filter successfully installed will be evaluated (in reverse order)
- * for each system call the task makes.
- *
- * Once current->seccomp.mode is non-zero, it may not be changed.
- *
- * Returns 0 on success or -EINVAL on failure.
- */
- static long seccomp_set_mode_filter(unsigned int flags,
- const char __user *filter)
- {
- const unsigned long seccomp_mode = SECCOMP_MODE_FILTER;
- struct seccomp_filter *prepared = NULL;
- long ret = -EINVAL;
- int listener = -1;
- struct file *listener_f = NULL;
- /* Validate flags. */
- if (flags & ~SECCOMP_FILTER_FLAG_MASK)
- return -EINVAL;
- /*
- * In the successful case, NEW_LISTENER returns the new listener fd.
- * But in the failure case, TSYNC returns the thread that died. If you
- * combine these two flags, there's no way to tell whether something
- * succeeded or failed. So, let's disallow this combination if the user
- * has not explicitly requested no errors from TSYNC.
- */
- if ((flags & SECCOMP_FILTER_FLAG_TSYNC) &&
- (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) &&
- ((flags & SECCOMP_FILTER_FLAG_TSYNC_ESRCH) == 0))
- return -EINVAL;
- /* Prepare the new filter before holding any locks. */
- prepared = seccomp_prepare_user_filter(filter);
- if (IS_ERR(prepared))
- return PTR_ERR(prepared);
- if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
- listener = get_unused_fd_flags(O_CLOEXEC);
- if (listener < 0) {
- ret = listener;
- goto out_free;
- }
- listener_f = init_listener(prepared);
- if (IS_ERR(listener_f)) {
- put_unused_fd(listener);
- ret = PTR_ERR(listener_f);
- goto out_free;
- }
- }
- /*
- * Make sure we cannot change seccomp or nnp state via TSYNC
- * while another thread is in the middle of calling exec.
- */
- if (flags & SECCOMP_FILTER_FLAG_TSYNC &&
- mutex_lock_killable(¤t->signal->cred_guard_mutex))
- goto out_put_fd;
- spin_lock_irq(¤t->sighand->siglock);
- if (!seccomp_may_assign_mode(seccomp_mode))
- goto out;
- if (has_duplicate_listener(prepared)) {
- ret = -EBUSY;
- goto out;
- }
- ret = seccomp_attach_filter(flags, prepared);
- if (ret)
- goto out;
- /* Do not free the successfully attached filter. */
- prepared = NULL;
- seccomp_assign_mode(current, seccomp_mode, flags);
- out:
- spin_unlock_irq(¤t->sighand->siglock);
- if (flags & SECCOMP_FILTER_FLAG_TSYNC)
- mutex_unlock(¤t->signal->cred_guard_mutex);
- out_put_fd:
- if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) {
- if (ret) {
- listener_f->private_data = NULL;
- fput(listener_f);
- put_unused_fd(listener);
- seccomp_notify_detach(prepared);
- } else {
- fd_install(listener, listener_f);
- ret = listener;
- }
- }
- out_free:
- seccomp_filter_free(prepared);
- return ret;
- }
- #else
- static inline long seccomp_set_mode_filter(unsigned int flags,
- const char __user *filter)
- {
- return -EINVAL;
- }
- #endif
- static long seccomp_get_action_avail(const char __user *uaction)
- {
- u32 action;
- if (copy_from_user(&action, uaction, sizeof(action)))
- return -EFAULT;
- switch (action) {
- case SECCOMP_RET_KILL_PROCESS:
- case SECCOMP_RET_KILL_THREAD:
- case SECCOMP_RET_TRAP:
- case SECCOMP_RET_ERRNO:
- case SECCOMP_RET_USER_NOTIF:
- case SECCOMP_RET_TRACE:
- case SECCOMP_RET_LOG:
- case SECCOMP_RET_ALLOW:
- break;
- default:
- return -EOPNOTSUPP;
- }
- return 0;
- }
- static long seccomp_get_notif_sizes(void __user *usizes)
- {
- struct seccomp_notif_sizes sizes = {
- .seccomp_notif = sizeof(struct seccomp_notif),
- .seccomp_notif_resp = sizeof(struct seccomp_notif_resp),
- .seccomp_data = sizeof(struct seccomp_data),
- };
- if (copy_to_user(usizes, &sizes, sizeof(sizes)))
- return -EFAULT;
- return 0;
- }
- /* Common entry point for both prctl and syscall. */
- static long do_seccomp(unsigned int op, unsigned int flags,
- void __user *uargs)
- {
- switch (op) {
- case SECCOMP_SET_MODE_STRICT:
- if (flags != 0 || uargs != NULL)
- return -EINVAL;
- return seccomp_set_mode_strict();
- case SECCOMP_SET_MODE_FILTER:
- return seccomp_set_mode_filter(flags, uargs);
- case SECCOMP_GET_ACTION_AVAIL:
- if (flags != 0)
- return -EINVAL;
- return seccomp_get_action_avail(uargs);
- case SECCOMP_GET_NOTIF_SIZES:
- if (flags != 0)
- return -EINVAL;
- return seccomp_get_notif_sizes(uargs);
- default:
- return -EINVAL;
- }
- }
- SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
- void __user *, uargs)
- {
- return do_seccomp(op, flags, uargs);
- }
- /**
- * prctl_set_seccomp: configures current->seccomp.mode
- * @seccomp_mode: requested mode to use
- * @filter: optional struct sock_fprog for use with SECCOMP_MODE_FILTER
- *
- * Returns 0 on success or -EINVAL on failure.
- */
- long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
- {
- unsigned int op;
- void __user *uargs;
- switch (seccomp_mode) {
- case SECCOMP_MODE_STRICT:
- op = SECCOMP_SET_MODE_STRICT;
- /*
- * Setting strict mode through prctl always ignored filter,
- * so make sure it is always NULL here to pass the internal
- * check in do_seccomp().
- */
- uargs = NULL;
- break;
- case SECCOMP_MODE_FILTER:
- op = SECCOMP_SET_MODE_FILTER;
- uargs = filter;
- break;
- default:
- return -EINVAL;
- }
- /* prctl interface doesn't have flags, so they are always zero. */
- return do_seccomp(op, 0, uargs);
- }
- #if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
- static struct seccomp_filter *get_nth_filter(struct task_struct *task,
- unsigned long filter_off)
- {
- struct seccomp_filter *orig, *filter;
- unsigned long count;
- /*
- * Note: this is only correct because the caller should be the (ptrace)
- * tracer of the task, otherwise lock_task_sighand is needed.
- */
- spin_lock_irq(&task->sighand->siglock);
- if (task->seccomp.mode != SECCOMP_MODE_FILTER) {
- spin_unlock_irq(&task->sighand->siglock);
- return ERR_PTR(-EINVAL);
- }
- orig = task->seccomp.filter;
- __get_seccomp_filter(orig);
- spin_unlock_irq(&task->sighand->siglock);
- count = 0;
- for (filter = orig; filter; filter = filter->prev)
- count++;
- if (filter_off >= count) {
- filter = ERR_PTR(-ENOENT);
- goto out;
- }
- count -= filter_off;
- for (filter = orig; filter && count > 1; filter = filter->prev)
- count--;
- if (WARN_ON(count != 1 || !filter)) {
- filter = ERR_PTR(-ENOENT);
- goto out;
- }
- __get_seccomp_filter(filter);
- out:
- __put_seccomp_filter(orig);
- return filter;
- }
- long seccomp_get_filter(struct task_struct *task, unsigned long filter_off,
- void __user *data)
- {
- struct seccomp_filter *filter;
- struct sock_fprog_kern *fprog;
- long ret;
- if (!capable(CAP_SYS_ADMIN) ||
- current->seccomp.mode != SECCOMP_MODE_DISABLED) {
- return -EACCES;
- }
- filter = get_nth_filter(task, filter_off);
- if (IS_ERR(filter))
- return PTR_ERR(filter);
- fprog = filter->prog->orig_prog;
- if (!fprog) {
- /* This must be a new non-cBPF filter, since we save
- * every cBPF filter's orig_prog above when
- * CONFIG_CHECKPOINT_RESTORE is enabled.
- */
- ret = -EMEDIUMTYPE;
- goto out;
- }
- ret = fprog->len;
- if (!data)
- goto out;
- if (copy_to_user(data, fprog->filter, bpf_classic_proglen(fprog)))
- ret = -EFAULT;
- out:
- __put_seccomp_filter(filter);
- return ret;
- }
- long seccomp_get_metadata(struct task_struct *task,
- unsigned long size, void __user *data)
- {
- long ret;
- struct seccomp_filter *filter;
- struct seccomp_metadata kmd = {};
- if (!capable(CAP_SYS_ADMIN) ||
- current->seccomp.mode != SECCOMP_MODE_DISABLED) {
- return -EACCES;
- }
- size = min_t(unsigned long, size, sizeof(kmd));
- if (size < sizeof(kmd.filter_off))
- return -EINVAL;
- if (copy_from_user(&kmd.filter_off, data, sizeof(kmd.filter_off)))
- return -EFAULT;
- filter = get_nth_filter(task, kmd.filter_off);
- if (IS_ERR(filter))
- return PTR_ERR(filter);
- if (filter->log)
- kmd.flags |= SECCOMP_FILTER_FLAG_LOG;
- ret = size;
- if (copy_to_user(data, &kmd, size))
- ret = -EFAULT;
- __put_seccomp_filter(filter);
- return ret;
- }
- #endif
- #ifdef CONFIG_SYSCTL
- /* Human readable action names for friendly sysctl interaction */
- #define SECCOMP_RET_KILL_PROCESS_NAME "kill_process"
- #define SECCOMP_RET_KILL_THREAD_NAME "kill_thread"
- #define SECCOMP_RET_TRAP_NAME "trap"
- #define SECCOMP_RET_ERRNO_NAME "errno"
- #define SECCOMP_RET_USER_NOTIF_NAME "user_notif"
- #define SECCOMP_RET_TRACE_NAME "trace"
- #define SECCOMP_RET_LOG_NAME "log"
- #define SECCOMP_RET_ALLOW_NAME "allow"
- static const char seccomp_actions_avail[] =
- SECCOMP_RET_KILL_PROCESS_NAME " "
- SECCOMP_RET_KILL_THREAD_NAME " "
- SECCOMP_RET_TRAP_NAME " "
- SECCOMP_RET_ERRNO_NAME " "
- SECCOMP_RET_USER_NOTIF_NAME " "
- SECCOMP_RET_TRACE_NAME " "
- SECCOMP_RET_LOG_NAME " "
- SECCOMP_RET_ALLOW_NAME;
- struct seccomp_log_name {
- u32 log;
- const char *name;
- };
- static const struct seccomp_log_name seccomp_log_names[] = {
- { SECCOMP_LOG_KILL_PROCESS, SECCOMP_RET_KILL_PROCESS_NAME },
- { SECCOMP_LOG_KILL_THREAD, SECCOMP_RET_KILL_THREAD_NAME },
- { SECCOMP_LOG_TRAP, SECCOMP_RET_TRAP_NAME },
- { SECCOMP_LOG_ERRNO, SECCOMP_RET_ERRNO_NAME },
- { SECCOMP_LOG_USER_NOTIF, SECCOMP_RET_USER_NOTIF_NAME },
- { SECCOMP_LOG_TRACE, SECCOMP_RET_TRACE_NAME },
- { SECCOMP_LOG_LOG, SECCOMP_RET_LOG_NAME },
- { SECCOMP_LOG_ALLOW, SECCOMP_RET_ALLOW_NAME },
- { }
- };
- static bool seccomp_names_from_actions_logged(char *names, size_t size,
- u32 actions_logged,
- const char *sep)
- {
- const struct seccomp_log_name *cur;
- bool append_sep = false;
- for (cur = seccomp_log_names; cur->name && size; cur++) {
- ssize_t ret;
- if (!(actions_logged & cur->log))
- continue;
- if (append_sep) {
- ret = strscpy(names, sep, size);
- if (ret < 0)
- return false;
- names += ret;
- size -= ret;
- } else
- append_sep = true;
- ret = strscpy(names, cur->name, size);
- if (ret < 0)
- return false;
- names += ret;
- size -= ret;
- }
- return true;
- }
- static bool seccomp_action_logged_from_name(u32 *action_logged,
- const char *name)
- {
- const struct seccomp_log_name *cur;
- for (cur = seccomp_log_names; cur->name; cur++) {
- if (!strcmp(cur->name, name)) {
- *action_logged = cur->log;
- return true;
- }
- }
- return false;
- }
- static bool seccomp_actions_logged_from_names(u32 *actions_logged, char *names)
- {
- char *name;
- *actions_logged = 0;
- while ((name = strsep(&names, " ")) && *name) {
- u32 action_logged = 0;
- if (!seccomp_action_logged_from_name(&action_logged, name))
- return false;
- *actions_logged |= action_logged;
- }
- return true;
- }
- static int read_actions_logged(struct ctl_table *ro_table, void *buffer,
- size_t *lenp, loff_t *ppos)
- {
- char names[sizeof(seccomp_actions_avail)];
- struct ctl_table table;
- memset(names, 0, sizeof(names));
- if (!seccomp_names_from_actions_logged(names, sizeof(names),
- seccomp_actions_logged, " "))
- return -EINVAL;
- table = *ro_table;
- table.data = names;
- table.maxlen = sizeof(names);
- return proc_dostring(&table, 0, buffer, lenp, ppos);
- }
- static int write_actions_logged(struct ctl_table *ro_table, void *buffer,
- size_t *lenp, loff_t *ppos, u32 *actions_logged)
- {
- char names[sizeof(seccomp_actions_avail)];
- struct ctl_table table;
- int ret;
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
- memset(names, 0, sizeof(names));
- table = *ro_table;
- table.data = names;
- table.maxlen = sizeof(names);
- ret = proc_dostring(&table, 1, buffer, lenp, ppos);
- if (ret)
- return ret;
- if (!seccomp_actions_logged_from_names(actions_logged, table.data))
- return -EINVAL;
- if (*actions_logged & SECCOMP_LOG_ALLOW)
- return -EINVAL;
- seccomp_actions_logged = *actions_logged;
- return 0;
- }
- static void audit_actions_logged(u32 actions_logged, u32 old_actions_logged,
- int ret)
- {
- char names[sizeof(seccomp_actions_avail)];
- char old_names[sizeof(seccomp_actions_avail)];
- const char *new = names;
- const char *old = old_names;
- if (!audit_enabled)
- return;
- memset(names, 0, sizeof(names));
- memset(old_names, 0, sizeof(old_names));
- if (ret)
- new = "?";
- else if (!actions_logged)
- new = "(none)";
- else if (!seccomp_names_from_actions_logged(names, sizeof(names),
- actions_logged, ","))
- new = "?";
- if (!old_actions_logged)
- old = "(none)";
- else if (!seccomp_names_from_actions_logged(old_names,
- sizeof(old_names),
- old_actions_logged, ","))
- old = "?";
- return audit_seccomp_actions_logged(new, old, !ret);
- }
- static int seccomp_actions_logged_handler(struct ctl_table *ro_table, int write,
- void *buffer, size_t *lenp,
- loff_t *ppos)
- {
- int ret;
- if (write) {
- u32 actions_logged = 0;
- u32 old_actions_logged = seccomp_actions_logged;
- ret = write_actions_logged(ro_table, buffer, lenp, ppos,
- &actions_logged);
- audit_actions_logged(actions_logged, old_actions_logged, ret);
- } else
- ret = read_actions_logged(ro_table, buffer, lenp, ppos);
- return ret;
- }
- static struct ctl_path seccomp_sysctl_path[] = {
- { .procname = "kernel", },
- { .procname = "seccomp", },
- { }
- };
- static struct ctl_table seccomp_sysctl_table[] = {
- {
- .procname = "actions_avail",
- .data = (void *) &seccomp_actions_avail,
- .maxlen = sizeof(seccomp_actions_avail),
- .mode = 0444,
- .proc_handler = proc_dostring,
- },
- {
- .procname = "actions_logged",
- .mode = 0644,
- .proc_handler = seccomp_actions_logged_handler,
- },
- { }
- };
- static int __init seccomp_sysctl_init(void)
- {
- struct ctl_table_header *hdr;
- hdr = register_sysctl_paths(seccomp_sysctl_path, seccomp_sysctl_table);
- if (!hdr)
- pr_warn("sysctl registration failed\n");
- else
- kmemleak_not_leak(hdr);
- return 0;
- }
- device_initcall(seccomp_sysctl_init)
- #endif /* CONFIG_SYSCTL */
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