123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469 |
- // SPDX-License-Identifier: GPL-2.0
- /*
- * NETLINK Policy advertisement to userspace
- *
- * Authors: Johannes Berg <johannes@sipsolutions.net>
- *
- * Copyright 2019 Intel Corporation
- */
- #include <linux/kernel.h>
- #include <linux/errno.h>
- #include <linux/types.h>
- #include <net/netlink.h>
- #define INITIAL_POLICIES_ALLOC 10
- struct netlink_policy_dump_state {
- unsigned int policy_idx;
- unsigned int attr_idx;
- unsigned int n_alloc;
- struct {
- const struct nla_policy *policy;
- unsigned int maxtype;
- } policies[];
- };
- static int add_policy(struct netlink_policy_dump_state **statep,
- const struct nla_policy *policy,
- unsigned int maxtype)
- {
- struct netlink_policy_dump_state *state = *statep;
- unsigned int n_alloc, i;
- if (!policy || !maxtype)
- return 0;
- for (i = 0; i < state->n_alloc; i++) {
- if (state->policies[i].policy == policy &&
- state->policies[i].maxtype == maxtype)
- return 0;
- if (!state->policies[i].policy) {
- state->policies[i].policy = policy;
- state->policies[i].maxtype = maxtype;
- return 0;
- }
- }
- n_alloc = state->n_alloc + INITIAL_POLICIES_ALLOC;
- state = krealloc(state, struct_size(state, policies, n_alloc),
- GFP_KERNEL);
- if (!state)
- return -ENOMEM;
- memset(&state->policies[state->n_alloc], 0,
- flex_array_size(state, policies, n_alloc - state->n_alloc));
- state->policies[state->n_alloc].policy = policy;
- state->policies[state->n_alloc].maxtype = maxtype;
- state->n_alloc = n_alloc;
- *statep = state;
- return 0;
- }
- /**
- * netlink_policy_dump_get_policy_idx - retrieve policy index
- * @state: the policy dump state
- * @policy: the policy to find
- * @maxtype: the policy's maxattr
- *
- * Returns: the index of the given policy in the dump state
- *
- * Call this to find a policy index when you've added multiple and e.g.
- * need to tell userspace which command has which policy (by index).
- *
- * Note: this will WARN and return 0 if the policy isn't found, which
- * means it wasn't added in the first place, which would be an
- * internal consistency bug.
- */
- int netlink_policy_dump_get_policy_idx(struct netlink_policy_dump_state *state,
- const struct nla_policy *policy,
- unsigned int maxtype)
- {
- unsigned int i;
- if (WARN_ON(!policy || !maxtype))
- return 0;
- for (i = 0; i < state->n_alloc; i++) {
- if (state->policies[i].policy == policy &&
- state->policies[i].maxtype == maxtype)
- return i;
- }
- WARN_ON(1);
- return 0;
- }
- static struct netlink_policy_dump_state *alloc_state(void)
- {
- struct netlink_policy_dump_state *state;
- state = kzalloc(struct_size(state, policies, INITIAL_POLICIES_ALLOC),
- GFP_KERNEL);
- if (!state)
- return ERR_PTR(-ENOMEM);
- state->n_alloc = INITIAL_POLICIES_ALLOC;
- return state;
- }
- /**
- * netlink_policy_dump_add_policy - add a policy to the dump
- * @pstate: state to add to, may be reallocated, must be %NULL the first time
- * @policy: the new policy to add to the dump
- * @maxtype: the new policy's max attr type
- *
- * Returns: 0 on success, a negative error code otherwise.
- *
- * Call this to allocate a policy dump state, and to add policies to it. This
- * should be called from the dump start() callback.
- *
- * Note: on failures, any previously allocated state is freed.
- */
- int netlink_policy_dump_add_policy(struct netlink_policy_dump_state **pstate,
- const struct nla_policy *policy,
- unsigned int maxtype)
- {
- struct netlink_policy_dump_state *state = *pstate;
- unsigned int policy_idx;
- int err;
- if (!state) {
- state = alloc_state();
- if (IS_ERR(state))
- return PTR_ERR(state);
- }
- /*
- * walk the policies and nested ones first, and build
- * a linear list of them.
- */
- err = add_policy(&state, policy, maxtype);
- if (err)
- return err;
- for (policy_idx = 0;
- policy_idx < state->n_alloc && state->policies[policy_idx].policy;
- policy_idx++) {
- const struct nla_policy *policy;
- unsigned int type;
- policy = state->policies[policy_idx].policy;
- for (type = 0;
- type <= state->policies[policy_idx].maxtype;
- type++) {
- switch (policy[type].type) {
- case NLA_NESTED:
- case NLA_NESTED_ARRAY:
- err = add_policy(&state,
- policy[type].nested_policy,
- policy[type].len);
- if (err)
- return err;
- break;
- default:
- break;
- }
- }
- }
- *pstate = state;
- return 0;
- }
- static bool
- netlink_policy_dump_finished(struct netlink_policy_dump_state *state)
- {
- return state->policy_idx >= state->n_alloc ||
- !state->policies[state->policy_idx].policy;
- }
- /**
- * netlink_policy_dump_loop - dumping loop indicator
- * @state: the policy dump state
- *
- * Returns: %true if the dump continues, %false otherwise
- *
- * Note: this frees the dump state when finishing
- */
- bool netlink_policy_dump_loop(struct netlink_policy_dump_state *state)
- {
- return !netlink_policy_dump_finished(state);
- }
- int netlink_policy_dump_attr_size_estimate(const struct nla_policy *pt)
- {
- /* nested + type */
- int common = 2 * nla_attr_size(sizeof(u32));
- switch (pt->type) {
- case NLA_UNSPEC:
- case NLA_REJECT:
- /* these actually don't need any space */
- return 0;
- case NLA_NESTED:
- case NLA_NESTED_ARRAY:
- /* common, policy idx, policy maxattr */
- return common + 2 * nla_attr_size(sizeof(u32));
- case NLA_U8:
- case NLA_U16:
- case NLA_U32:
- case NLA_U64:
- case NLA_MSECS:
- case NLA_S8:
- case NLA_S16:
- case NLA_S32:
- case NLA_S64:
- /* maximum is common, u64 min/max with padding */
- return common +
- 2 * (nla_attr_size(0) + nla_attr_size(sizeof(u64)));
- case NLA_BITFIELD32:
- return common + nla_attr_size(sizeof(u32));
- case NLA_STRING:
- case NLA_NUL_STRING:
- case NLA_BINARY:
- /* maximum is common, u32 min-length/max-length */
- return common + 2 * nla_attr_size(sizeof(u32));
- case NLA_FLAG:
- return common;
- }
- /* this should then cause a warning later */
- return 0;
- }
- static int
- __netlink_policy_dump_write_attr(struct netlink_policy_dump_state *state,
- struct sk_buff *skb,
- const struct nla_policy *pt,
- int nestattr)
- {
- int estimate = netlink_policy_dump_attr_size_estimate(pt);
- enum netlink_attribute_type type;
- struct nlattr *attr;
- attr = nla_nest_start(skb, nestattr);
- if (!attr)
- return -ENOBUFS;
- switch (pt->type) {
- default:
- case NLA_UNSPEC:
- case NLA_REJECT:
- /* skip - use NLA_MIN_LEN to advertise such */
- nla_nest_cancel(skb, attr);
- return -ENODATA;
- case NLA_NESTED:
- type = NL_ATTR_TYPE_NESTED;
- fallthrough;
- case NLA_NESTED_ARRAY:
- if (pt->type == NLA_NESTED_ARRAY)
- type = NL_ATTR_TYPE_NESTED_ARRAY;
- if (state && pt->nested_policy && pt->len &&
- (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_IDX,
- netlink_policy_dump_get_policy_idx(state,
- pt->nested_policy,
- pt->len)) ||
- nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_MAXTYPE,
- pt->len)))
- goto nla_put_failure;
- break;
- case NLA_U8:
- case NLA_U16:
- case NLA_U32:
- case NLA_U64:
- case NLA_MSECS: {
- struct netlink_range_validation range;
- if (pt->type == NLA_U8)
- type = NL_ATTR_TYPE_U8;
- else if (pt->type == NLA_U16)
- type = NL_ATTR_TYPE_U16;
- else if (pt->type == NLA_U32)
- type = NL_ATTR_TYPE_U32;
- else
- type = NL_ATTR_TYPE_U64;
- if (pt->validation_type == NLA_VALIDATE_MASK) {
- if (nla_put_u64_64bit(skb, NL_POLICY_TYPE_ATTR_MASK,
- pt->mask,
- NL_POLICY_TYPE_ATTR_PAD))
- goto nla_put_failure;
- break;
- }
- nla_get_range_unsigned(pt, &range);
- if (nla_put_u64_64bit(skb, NL_POLICY_TYPE_ATTR_MIN_VALUE_U,
- range.min, NL_POLICY_TYPE_ATTR_PAD) ||
- nla_put_u64_64bit(skb, NL_POLICY_TYPE_ATTR_MAX_VALUE_U,
- range.max, NL_POLICY_TYPE_ATTR_PAD))
- goto nla_put_failure;
- break;
- }
- case NLA_S8:
- case NLA_S16:
- case NLA_S32:
- case NLA_S64: {
- struct netlink_range_validation_signed range;
- if (pt->type == NLA_S8)
- type = NL_ATTR_TYPE_S8;
- else if (pt->type == NLA_S16)
- type = NL_ATTR_TYPE_S16;
- else if (pt->type == NLA_S32)
- type = NL_ATTR_TYPE_S32;
- else
- type = NL_ATTR_TYPE_S64;
- nla_get_range_signed(pt, &range);
- if (nla_put_s64(skb, NL_POLICY_TYPE_ATTR_MIN_VALUE_S,
- range.min, NL_POLICY_TYPE_ATTR_PAD) ||
- nla_put_s64(skb, NL_POLICY_TYPE_ATTR_MAX_VALUE_S,
- range.max, NL_POLICY_TYPE_ATTR_PAD))
- goto nla_put_failure;
- break;
- }
- case NLA_BITFIELD32:
- type = NL_ATTR_TYPE_BITFIELD32;
- if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_BITFIELD32_MASK,
- pt->bitfield32_valid))
- goto nla_put_failure;
- break;
- case NLA_STRING:
- case NLA_NUL_STRING:
- case NLA_BINARY:
- if (pt->type == NLA_STRING)
- type = NL_ATTR_TYPE_STRING;
- else if (pt->type == NLA_NUL_STRING)
- type = NL_ATTR_TYPE_NUL_STRING;
- else
- type = NL_ATTR_TYPE_BINARY;
- if (pt->validation_type == NLA_VALIDATE_RANGE ||
- pt->validation_type == NLA_VALIDATE_RANGE_WARN_TOO_LONG) {
- struct netlink_range_validation range;
- nla_get_range_unsigned(pt, &range);
- if (range.min &&
- nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MIN_LENGTH,
- range.min))
- goto nla_put_failure;
- if (range.max < U16_MAX &&
- nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MAX_LENGTH,
- range.max))
- goto nla_put_failure;
- } else if (pt->len &&
- nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MAX_LENGTH,
- pt->len)) {
- goto nla_put_failure;
- }
- break;
- case NLA_FLAG:
- type = NL_ATTR_TYPE_FLAG;
- break;
- }
- if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_TYPE, type))
- goto nla_put_failure;
- nla_nest_end(skb, attr);
- WARN_ON(attr->nla_len > estimate);
- return 0;
- nla_put_failure:
- nla_nest_cancel(skb, attr);
- return -ENOBUFS;
- }
- /**
- * netlink_policy_dump_write_attr - write a given attribute policy
- * @skb: the message skb to write to
- * @pt: the attribute's policy
- * @nestattr: the nested attribute ID to use
- *
- * Returns: 0 on success, an error code otherwise; -%ENODATA is
- * special, indicating that there's no policy data and
- * the attribute is generally rejected.
- */
- int netlink_policy_dump_write_attr(struct sk_buff *skb,
- const struct nla_policy *pt,
- int nestattr)
- {
- return __netlink_policy_dump_write_attr(NULL, skb, pt, nestattr);
- }
- /**
- * netlink_policy_dump_write - write current policy dump attributes
- * @skb: the message skb to write to
- * @state: the policy dump state
- *
- * Returns: 0 on success, an error code otherwise
- */
- int netlink_policy_dump_write(struct sk_buff *skb,
- struct netlink_policy_dump_state *state)
- {
- const struct nla_policy *pt;
- struct nlattr *policy;
- bool again;
- int err;
- send_attribute:
- again = false;
- pt = &state->policies[state->policy_idx].policy[state->attr_idx];
- policy = nla_nest_start(skb, state->policy_idx);
- if (!policy)
- return -ENOBUFS;
- err = __netlink_policy_dump_write_attr(state, skb, pt, state->attr_idx);
- if (err == -ENODATA) {
- nla_nest_cancel(skb, policy);
- again = true;
- goto next;
- } else if (err) {
- goto nla_put_failure;
- }
- /* finish and move state to next attribute */
- nla_nest_end(skb, policy);
- next:
- state->attr_idx += 1;
- if (state->attr_idx > state->policies[state->policy_idx].maxtype) {
- state->attr_idx = 0;
- state->policy_idx++;
- }
- if (again) {
- if (netlink_policy_dump_finished(state))
- return -ENODATA;
- goto send_attribute;
- }
- return 0;
- nla_put_failure:
- nla_nest_cancel(skb, policy);
- return -ENOBUFS;
- }
- /**
- * netlink_policy_dump_free - free policy dump state
- * @state: the policy dump state to free
- *
- * Call this from the done() method to ensure dump state is freed.
- */
- void netlink_policy_dump_free(struct netlink_policy_dump_state *state)
- {
- kfree(state);
- }
|