// SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2019 Facebook */ #include #include #include #include #include #include #include #include #include #include #include #define BPF_LOCAL_STORAGE_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_CLONE) DEFINE_BPF_STORAGE_CACHE(sk_cache); struct bpf_local_storage_map_bucket { struct hlist_head list; raw_spinlock_t lock; }; /* Thp map is not the primary owner of a bpf_local_storage_elem. * Instead, the container object (eg. sk->sk_bpf_storage) is. * * The map (bpf_local_storage_map) is for two purposes * 1. Define the size of the "local storage". It is * the map's value_size. * * 2. Maintain a list to keep track of all elems such * that they can be cleaned up during the map destruction. * * When a bpf local storage is being looked up for a * particular object, the "bpf_map" pointer is actually used * as the "key" to search in the list of elem in * the respective bpf_local_storage owned by the object. * * e.g. sk->sk_bpf_storage is the mini-map with the "bpf_map" pointer * as the searching key. */ struct bpf_local_storage_map { struct bpf_map map; /* Lookup elem does not require accessing the map. * * Updating/Deleting requires a bucket lock to * link/unlink the elem from the map. Having * multiple buckets to improve contention. */ struct bpf_local_storage_map_bucket *buckets; u32 bucket_log; u16 elem_size; u16 cache_idx; }; struct bpf_local_storage_data { /* smap is used as the searching key when looking up * from the object's bpf_local_storage. * * Put it in the same cacheline as the data to minimize * the number of cachelines access during the cache hit case. */ struct bpf_local_storage_map __rcu *smap; u8 data[] __aligned(8); }; /* Linked to bpf_local_storage and bpf_local_storage_map */ struct bpf_local_storage_elem { struct hlist_node map_node; /* Linked to bpf_local_storage_map */ struct hlist_node snode; /* Linked to bpf_local_storage */ struct bpf_local_storage __rcu *local_storage; struct rcu_head rcu; /* 8 bytes hole */ /* The data is stored in aother cacheline to minimize * the number of cachelines access during a cache hit. */ struct bpf_local_storage_data sdata ____cacheline_aligned; }; #define SELEM(_SDATA) \ container_of((_SDATA), struct bpf_local_storage_elem, sdata) #define SDATA(_SELEM) (&(_SELEM)->sdata) struct bpf_local_storage { struct bpf_local_storage_data __rcu *cache[BPF_LOCAL_STORAGE_CACHE_SIZE]; struct hlist_head list; /* List of bpf_local_storage_elem */ struct sock *owner; /* The object that owns the above "list" of * bpf_local_storage_elem. */ struct rcu_head rcu; raw_spinlock_t lock; /* Protect adding/removing from the "list" */ }; static struct bpf_local_storage_map_bucket * select_bucket(struct bpf_local_storage_map *smap, struct bpf_local_storage_elem *selem) { return &smap->buckets[hash_ptr(selem, smap->bucket_log)]; } static int omem_charge(struct sock *sk, unsigned int size) { /* same check as in sock_kmalloc() */ if (size <= sysctl_optmem_max && atomic_read(&sk->sk_omem_alloc) + size < sysctl_optmem_max) { atomic_add(size, &sk->sk_omem_alloc); return 0; } return -ENOMEM; } static bool selem_linked_to_storage(const struct bpf_local_storage_elem *selem) { return !hlist_unhashed(&selem->snode); } static bool selem_linked_to_map(const struct bpf_local_storage_elem *selem) { return !hlist_unhashed(&selem->map_node); } static struct bpf_local_storage_elem * bpf_selem_alloc(struct bpf_local_storage_map *smap, struct sock *sk, void *value, bool charge_omem) { struct bpf_local_storage_elem *selem; if (charge_omem && omem_charge(sk, smap->elem_size)) return NULL; selem = kzalloc(smap->elem_size, GFP_ATOMIC | __GFP_NOWARN); if (selem) { if (value) memcpy(SDATA(selem)->data, value, smap->map.value_size); return selem; } if (charge_omem) atomic_sub(smap->elem_size, &sk->sk_omem_alloc); return NULL; } /* local_storage->lock must be held and selem->local_storage == local_storage. * The caller must ensure selem->smap is still valid to be * dereferenced for its smap->elem_size and smap->cache_idx. */ static bool bpf_selem_unlink_storage_nolock(struct bpf_local_storage *local_storage, struct bpf_local_storage_elem *selem, bool uncharge_omem) { struct bpf_local_storage_map *smap; bool free_local_storage; struct sock *sk; smap = rcu_dereference(SDATA(selem)->smap); sk = local_storage->owner; /* All uncharging on the owner must be done first. * The owner may be freed once the last selem is unlinked * from local_storage. */ if (uncharge_omem) atomic_sub(smap->elem_size, &sk->sk_omem_alloc); free_local_storage = hlist_is_singular_node(&selem->snode, &local_storage->list); if (free_local_storage) { atomic_sub(sizeof(struct bpf_local_storage), &sk->sk_omem_alloc); local_storage->owner = NULL; /* After this RCU_INIT, sk may be freed and cannot be used */ RCU_INIT_POINTER(sk->sk_bpf_storage, NULL); /* local_storage is not freed now. local_storage->lock is * still held and raw_spin_unlock_bh(&local_storage->lock) * will be done by the caller. * * Although the unlock will be done under * rcu_read_lock(), it is more intutivie to * read if kfree_rcu(local_storage, rcu) is done * after the raw_spin_unlock_bh(&local_storage->lock). * * Hence, a "bool free_local_storage" is returned * to the caller which then calls the kfree_rcu() * after unlock. */ } hlist_del_init_rcu(&selem->snode); if (rcu_access_pointer(local_storage->cache[smap->cache_idx]) == SDATA(selem)) RCU_INIT_POINTER(local_storage->cache[smap->cache_idx], NULL); kfree_rcu(selem, rcu); return free_local_storage; } static void __bpf_selem_unlink_storage(struct bpf_local_storage_elem *selem) { struct bpf_local_storage *local_storage; bool free_local_storage = false; if (unlikely(!selem_linked_to_storage(selem))) /* selem has already been unlinked from sk */ return; local_storage = rcu_dereference(selem->local_storage); raw_spin_lock_bh(&local_storage->lock); if (likely(selem_linked_to_storage(selem))) free_local_storage = bpf_selem_unlink_storage_nolock(local_storage, selem, true); raw_spin_unlock_bh(&local_storage->lock); if (free_local_storage) kfree_rcu(local_storage, rcu); } static void bpf_selem_link_storage_nolock(struct bpf_local_storage *local_storage, struct bpf_local_storage_elem *selem) { RCU_INIT_POINTER(selem->local_storage, local_storage); hlist_add_head(&selem->snode, &local_storage->list); } static void bpf_selem_unlink_map(struct bpf_local_storage_elem *selem) { struct bpf_local_storage_map *smap; struct bpf_local_storage_map_bucket *b; if (unlikely(!selem_linked_to_map(selem))) /* selem has already be unlinked from smap */ return; smap = rcu_dereference(SDATA(selem)->smap); b = select_bucket(smap, selem); raw_spin_lock_bh(&b->lock); if (likely(selem_linked_to_map(selem))) hlist_del_init_rcu(&selem->map_node); raw_spin_unlock_bh(&b->lock); } static void bpf_selem_link_map(struct bpf_local_storage_map *smap, struct bpf_local_storage_elem *selem) { struct bpf_local_storage_map_bucket *b = select_bucket(smap, selem); raw_spin_lock_bh(&b->lock); RCU_INIT_POINTER(SDATA(selem)->smap, smap); hlist_add_head_rcu(&selem->map_node, &b->list); raw_spin_unlock_bh(&b->lock); } static void bpf_selem_unlink(struct bpf_local_storage_elem *selem) { /* Always unlink from map before unlinking from local_storage * because selem will be freed after successfully unlinked from * the local_storage. */ bpf_selem_unlink_map(selem); __bpf_selem_unlink_storage(selem); } static struct bpf_local_storage_data * bpf_local_storage_lookup(struct bpf_local_storage *local_storage, struct bpf_local_storage_map *smap, bool cacheit_lockit) { struct bpf_local_storage_data *sdata; struct bpf_local_storage_elem *selem; /* Fast path (cache hit) */ sdata = rcu_dereference(local_storage->cache[smap->cache_idx]); if (sdata && rcu_access_pointer(sdata->smap) == smap) return sdata; /* Slow path (cache miss) */ hlist_for_each_entry_rcu(selem, &local_storage->list, snode) if (rcu_access_pointer(SDATA(selem)->smap) == smap) break; if (!selem) return NULL; sdata = SDATA(selem); if (cacheit_lockit) { /* spinlock is needed to avoid racing with the * parallel delete. Otherwise, publishing an already * deleted sdata to the cache will become a use-after-free * problem in the next bpf_local_storage_lookup(). */ raw_spin_lock_bh(&local_storage->lock); if (selem_linked_to_storage(selem)) rcu_assign_pointer(local_storage->cache[smap->cache_idx], sdata); raw_spin_unlock_bh(&local_storage->lock); } return sdata; } static struct bpf_local_storage_data * sk_storage_lookup(struct sock *sk, struct bpf_map *map, bool cacheit_lockit) { struct bpf_local_storage *sk_storage; struct bpf_local_storage_map *smap; sk_storage = rcu_dereference(sk->sk_bpf_storage); if (!sk_storage) return NULL; smap = (struct bpf_local_storage_map *)map; return bpf_local_storage_lookup(sk_storage, smap, cacheit_lockit); } static int check_flags(const struct bpf_local_storage_data *old_sdata, u64 map_flags) { if (old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST) /* elem already exists */ return -EEXIST; if (!old_sdata && (map_flags & ~BPF_F_LOCK) == BPF_EXIST) /* elem doesn't exist, cannot update it */ return -ENOENT; return 0; } static int sk_storage_alloc(struct sock *sk, struct bpf_local_storage_map *smap, struct bpf_local_storage_elem *first_selem) { struct bpf_local_storage *prev_sk_storage, *sk_storage; int err; err = omem_charge(sk, sizeof(*sk_storage)); if (err) return err; sk_storage = kzalloc(sizeof(*sk_storage), GFP_ATOMIC | __GFP_NOWARN); if (!sk_storage) { err = -ENOMEM; goto uncharge; } INIT_HLIST_HEAD(&sk_storage->list); raw_spin_lock_init(&sk_storage->lock); sk_storage->owner = sk; bpf_selem_link_storage_nolock(sk_storage, first_selem); bpf_selem_link_map(smap, first_selem); /* Publish sk_storage to sk. sk->sk_lock cannot be acquired. * Hence, atomic ops is used to set sk->sk_bpf_storage * from NULL to the newly allocated sk_storage ptr. * * From now on, the sk->sk_bpf_storage pointer is protected * by the sk_storage->lock. Hence, when freeing * the sk->sk_bpf_storage, the sk_storage->lock must * be held before setting sk->sk_bpf_storage to NULL. */ prev_sk_storage = cmpxchg((struct bpf_local_storage **)&sk->sk_bpf_storage, NULL, sk_storage); if (unlikely(prev_sk_storage)) { bpf_selem_unlink_map(first_selem); err = -EAGAIN; goto uncharge; /* Note that even first_selem was linked to smap's * bucket->list, first_selem can be freed immediately * (instead of kfree_rcu) because * bpf_local_storage_map_free() does a * synchronize_rcu() before walking the bucket->list. * Hence, no one is accessing selem from the * bucket->list under rcu_read_lock(). */ } return 0; uncharge: kfree(sk_storage); atomic_sub(sizeof(*sk_storage), &sk->sk_omem_alloc); return err; } /* sk cannot be going away because it is linking new elem * to sk->sk_bpf_storage. (i.e. sk->sk_refcnt cannot be 0). * Otherwise, it will become a leak (and other memory issues * during map destruction). */ static struct bpf_local_storage_data * bpf_local_storage_update(struct sock *sk, struct bpf_map *map, void *value, u64 map_flags) { struct bpf_local_storage_data *old_sdata = NULL; struct bpf_local_storage_elem *selem; struct bpf_local_storage *local_storage; struct bpf_local_storage_map *smap; int err; /* BPF_EXIST and BPF_NOEXIST cannot be both set */ if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST) || /* BPF_F_LOCK can only be used in a value with spin_lock */ unlikely((map_flags & BPF_F_LOCK) && !map_value_has_spin_lock(map))) return ERR_PTR(-EINVAL); smap = (struct bpf_local_storage_map *)map; local_storage = rcu_dereference(sk->sk_bpf_storage); if (!local_storage || hlist_empty(&local_storage->list)) { /* Very first elem for the owner */ err = check_flags(NULL, map_flags); if (err) return ERR_PTR(err); selem = bpf_selem_alloc(smap, sk, value, true); if (!selem) return ERR_PTR(-ENOMEM); err = sk_storage_alloc(sk, smap, selem); if (err) { kfree(selem); atomic_sub(smap->elem_size, &sk->sk_omem_alloc); return ERR_PTR(err); } return SDATA(selem); } if ((map_flags & BPF_F_LOCK) && !(map_flags & BPF_NOEXIST)) { /* Hoping to find an old_sdata to do inline update * such that it can avoid taking the local_storage->lock * and changing the lists. */ old_sdata = bpf_local_storage_lookup(local_storage, smap, false); err = check_flags(old_sdata, map_flags); if (err) return ERR_PTR(err); if (old_sdata && selem_linked_to_storage(SELEM(old_sdata))) { copy_map_value_locked(map, old_sdata->data, value, false); return old_sdata; } } raw_spin_lock_bh(&local_storage->lock); /* Recheck local_storage->list under local_storage->lock */ if (unlikely(hlist_empty(&local_storage->list))) { /* A parallel del is happening and local_storage is going * away. It has just been checked before, so very * unlikely. Return instead of retry to keep things * simple. */ err = -EAGAIN; goto unlock_err; } old_sdata = bpf_local_storage_lookup(local_storage, smap, false); err = check_flags(old_sdata, map_flags); if (err) goto unlock_err; if (old_sdata && (map_flags & BPF_F_LOCK)) { copy_map_value_locked(map, old_sdata->data, value, false); selem = SELEM(old_sdata); goto unlock; } /* local_storage->lock is held. Hence, we are sure * we can unlink and uncharge the old_sdata successfully * later. Hence, instead of charging the new selem now * and then uncharge the old selem later (which may cause * a potential but unnecessary charge failure), avoid taking * a charge at all here (the "!old_sdata" check) and the * old_sdata will not be uncharged later during * bpf_selem_unlink_storage_nolock(). */ selem = bpf_selem_alloc(smap, sk, value, !old_sdata); if (!selem) { err = -ENOMEM; goto unlock_err; } /* First, link the new selem to the map */ bpf_selem_link_map(smap, selem); /* Second, link (and publish) the new selem to local_storage */ bpf_selem_link_storage_nolock(local_storage, selem); /* Third, remove old selem, SELEM(old_sdata) */ if (old_sdata) { bpf_selem_unlink_map(SELEM(old_sdata)); bpf_selem_unlink_storage_nolock(local_storage, SELEM(old_sdata), false); } unlock: raw_spin_unlock_bh(&local_storage->lock); return SDATA(selem); unlock_err: raw_spin_unlock_bh(&local_storage->lock); return ERR_PTR(err); } static int sk_storage_delete(struct sock *sk, struct bpf_map *map) { struct bpf_local_storage_data *sdata; sdata = sk_storage_lookup(sk, map, false); if (!sdata) return -ENOENT; bpf_selem_unlink(SELEM(sdata)); return 0; } u16 bpf_local_storage_cache_idx_get(struct bpf_local_storage_cache *cache) { u64 min_usage = U64_MAX; u16 i, res = 0; spin_lock(&cache->idx_lock); for (i = 0; i < BPF_LOCAL_STORAGE_CACHE_SIZE; i++) { if (cache->idx_usage_counts[i] < min_usage) { min_usage = cache->idx_usage_counts[i]; res = i; /* Found a free cache_idx */ if (!min_usage) break; } } cache->idx_usage_counts[res]++; spin_unlock(&cache->idx_lock); return res; } void bpf_local_storage_cache_idx_free(struct bpf_local_storage_cache *cache, u16 idx) { spin_lock(&cache->idx_lock); cache->idx_usage_counts[idx]--; spin_unlock(&cache->idx_lock); } /* Called by __sk_destruct() & bpf_sk_storage_clone() */ void bpf_sk_storage_free(struct sock *sk) { struct bpf_local_storage_elem *selem; struct bpf_local_storage *sk_storage; bool free_sk_storage = false; struct hlist_node *n; rcu_read_lock(); sk_storage = rcu_dereference(sk->sk_bpf_storage); if (!sk_storage) { rcu_read_unlock(); return; } /* Netiher the bpf_prog nor the bpf-map's syscall * could be modifying the sk_storage->list now. * Thus, no elem can be added-to or deleted-from the * sk_storage->list by the bpf_prog or by the bpf-map's syscall. * * It is racing with bpf_local_storage_map_free() alone * when unlinking elem from the sk_storage->list and * the map's bucket->list. */ raw_spin_lock_bh(&sk_storage->lock); hlist_for_each_entry_safe(selem, n, &sk_storage->list, snode) { /* Always unlink from map before unlinking from * sk_storage. */ bpf_selem_unlink_map(selem); free_sk_storage = bpf_selem_unlink_storage_nolock(sk_storage, selem, true); } raw_spin_unlock_bh(&sk_storage->lock); rcu_read_unlock(); if (free_sk_storage) kfree_rcu(sk_storage, rcu); } static void bpf_local_storage_map_free(struct bpf_map *map) { struct bpf_local_storage_elem *selem; struct bpf_local_storage_map *smap; struct bpf_local_storage_map_bucket *b; unsigned int i; smap = (struct bpf_local_storage_map *)map; bpf_local_storage_cache_idx_free(&sk_cache, smap->cache_idx); /* Note that this map might be concurrently cloned from * bpf_sk_storage_clone. Wait for any existing bpf_sk_storage_clone * RCU read section to finish before proceeding. New RCU * read sections should be prevented via bpf_map_inc_not_zero. */ synchronize_rcu(); /* bpf prog and the userspace can no longer access this map * now. No new selem (of this map) can be added * to the owner->storage or to the map bucket's list. * * The elem of this map can be cleaned up here * or when the storage is freed e.g. * by bpf_sk_storage_free() during __sk_destruct(). */ for (i = 0; i < (1U << smap->bucket_log); i++) { b = &smap->buckets[i]; rcu_read_lock(); /* No one is adding to b->list now */ while ((selem = hlist_entry_safe( rcu_dereference_raw(hlist_first_rcu(&b->list)), struct bpf_local_storage_elem, map_node))) { bpf_selem_unlink(selem); cond_resched_rcu(); } rcu_read_unlock(); } /* While freeing the storage we may still need to access the map. * * e.g. when bpf_sk_storage_free() has unlinked selem from the map * which then made the above while((selem = ...)) loop * exit immediately. * * However, while freeing the storage one still needs to access the * smap->elem_size to do the uncharging in * bpf_selem_unlink_storage_nolock(). * * Hence, wait another rcu grace period for the storage to be freed. */ synchronize_rcu(); kvfree(smap->buckets); kfree(map); } /* U16_MAX is much more than enough for sk local storage * considering a tcp_sock is ~2k. */ #define BPF_LOCAL_STORAGE_MAX_VALUE_SIZE \ min_t(u32, \ (KMALLOC_MAX_SIZE - MAX_BPF_STACK - \ sizeof(struct bpf_local_storage_elem)), \ (U16_MAX - sizeof(struct bpf_local_storage_elem))) static int bpf_local_storage_map_alloc_check(union bpf_attr *attr) { if (attr->map_flags & ~BPF_LOCAL_STORAGE_CREATE_FLAG_MASK || !(attr->map_flags & BPF_F_NO_PREALLOC) || attr->max_entries || attr->key_size != sizeof(int) || !attr->value_size || /* Enforce BTF for userspace sk dumping */ !attr->btf_key_type_id || !attr->btf_value_type_id) return -EINVAL; if (!bpf_capable()) return -EPERM; if (attr->value_size > BPF_LOCAL_STORAGE_MAX_VALUE_SIZE) return -E2BIG; return 0; } static struct bpf_map *bpf_local_storage_map_alloc(union bpf_attr *attr) { struct bpf_local_storage_map *smap; unsigned int i; u32 nbuckets; u64 cost; int ret; smap = kzalloc(sizeof(*smap), GFP_USER | __GFP_NOWARN); if (!smap) return ERR_PTR(-ENOMEM); bpf_map_init_from_attr(&smap->map, attr); nbuckets = roundup_pow_of_two(num_possible_cpus()); /* Use at least 2 buckets, select_bucket() is undefined behavior with 1 bucket */ nbuckets = max_t(u32, 2, nbuckets); smap->bucket_log = ilog2(nbuckets); cost = sizeof(*smap->buckets) * nbuckets + sizeof(*smap); ret = bpf_map_charge_init(&smap->map.memory, cost); if (ret < 0) { kfree(smap); return ERR_PTR(ret); } smap->buckets = kvcalloc(sizeof(*smap->buckets), nbuckets, GFP_USER | __GFP_NOWARN); if (!smap->buckets) { bpf_map_charge_finish(&smap->map.memory); kfree(smap); return ERR_PTR(-ENOMEM); } for (i = 0; i < nbuckets; i++) { INIT_HLIST_HEAD(&smap->buckets[i].list); raw_spin_lock_init(&smap->buckets[i].lock); } smap->elem_size = sizeof(struct bpf_local_storage_elem) + attr->value_size; smap->cache_idx = bpf_local_storage_cache_idx_get(&sk_cache); return &smap->map; } static int notsupp_get_next_key(struct bpf_map *map, void *key, void *next_key) { return -ENOTSUPP; } static int bpf_local_storage_map_check_btf(const struct bpf_map *map, const struct btf *btf, const struct btf_type *key_type, const struct btf_type *value_type) { u32 int_data; if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT) return -EINVAL; int_data = *(u32 *)(key_type + 1); if (BTF_INT_BITS(int_data) != 32 || BTF_INT_OFFSET(int_data)) return -EINVAL; return 0; } static void *bpf_fd_sk_storage_lookup_elem(struct bpf_map *map, void *key) { struct bpf_local_storage_data *sdata; struct socket *sock; int fd, err; fd = *(int *)key; sock = sockfd_lookup(fd, &err); if (sock) { sdata = sk_storage_lookup(sock->sk, map, true); sockfd_put(sock); return sdata ? sdata->data : NULL; } return ERR_PTR(err); } static int bpf_fd_sk_storage_update_elem(struct bpf_map *map, void *key, void *value, u64 map_flags) { struct bpf_local_storage_data *sdata; struct socket *sock; int fd, err; fd = *(int *)key; sock = sockfd_lookup(fd, &err); if (sock) { sdata = bpf_local_storage_update(sock->sk, map, value, map_flags); sockfd_put(sock); return PTR_ERR_OR_ZERO(sdata); } return err; } static int bpf_fd_sk_storage_delete_elem(struct bpf_map *map, void *key) { struct socket *sock; int fd, err; fd = *(int *)key; sock = sockfd_lookup(fd, &err); if (sock) { err = sk_storage_delete(sock->sk, map); sockfd_put(sock); return err; } return err; } static struct bpf_local_storage_elem * bpf_sk_storage_clone_elem(struct sock *newsk, struct bpf_local_storage_map *smap, struct bpf_local_storage_elem *selem) { struct bpf_local_storage_elem *copy_selem; copy_selem = bpf_selem_alloc(smap, newsk, NULL, true); if (!copy_selem) return NULL; if (map_value_has_spin_lock(&smap->map)) copy_map_value_locked(&smap->map, SDATA(copy_selem)->data, SDATA(selem)->data, true); else copy_map_value(&smap->map, SDATA(copy_selem)->data, SDATA(selem)->data); return copy_selem; } int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk) { struct bpf_local_storage *new_sk_storage = NULL; struct bpf_local_storage *sk_storage; struct bpf_local_storage_elem *selem; int ret = 0; RCU_INIT_POINTER(newsk->sk_bpf_storage, NULL); rcu_read_lock(); sk_storage = rcu_dereference(sk->sk_bpf_storage); if (!sk_storage || hlist_empty(&sk_storage->list)) goto out; hlist_for_each_entry_rcu(selem, &sk_storage->list, snode) { struct bpf_local_storage_elem *copy_selem; struct bpf_local_storage_map *smap; struct bpf_map *map; smap = rcu_dereference(SDATA(selem)->smap); if (!(smap->map.map_flags & BPF_F_CLONE)) continue; /* Note that for lockless listeners adding new element * here can race with cleanup in bpf_local_storage_map_free. * Try to grab map refcnt to make sure that it's still * alive and prevent concurrent removal. */ map = bpf_map_inc_not_zero(&smap->map); if (IS_ERR(map)) continue; copy_selem = bpf_sk_storage_clone_elem(newsk, smap, selem); if (!copy_selem) { ret = -ENOMEM; bpf_map_put(map); goto out; } if (new_sk_storage) { bpf_selem_link_map(smap, copy_selem); bpf_selem_link_storage_nolock(new_sk_storage, copy_selem); } else { ret = sk_storage_alloc(newsk, smap, copy_selem); if (ret) { kfree(copy_selem); atomic_sub(smap->elem_size, &newsk->sk_omem_alloc); bpf_map_put(map); goto out; } new_sk_storage = rcu_dereference(copy_selem->local_storage); } bpf_map_put(map); } out: rcu_read_unlock(); /* In case of an error, don't free anything explicitly here, the * caller is responsible to call bpf_sk_storage_free. */ return ret; } BPF_CALL_4(bpf_sk_storage_get, struct bpf_map *, map, struct sock *, sk, void *, value, u64, flags) { struct bpf_local_storage_data *sdata; if (flags > BPF_SK_STORAGE_GET_F_CREATE) return (unsigned long)NULL; sdata = sk_storage_lookup(sk, map, true); if (sdata) return (unsigned long)sdata->data; if (flags == BPF_SK_STORAGE_GET_F_CREATE && /* Cannot add new elem to a going away sk. * Otherwise, the new elem may become a leak * (and also other memory issues during map * destruction). */ refcount_inc_not_zero(&sk->sk_refcnt)) { sdata = bpf_local_storage_update(sk, map, value, BPF_NOEXIST); /* sk must be a fullsock (guaranteed by verifier), * so sock_gen_put() is unnecessary. */ sock_put(sk); return IS_ERR(sdata) ? (unsigned long)NULL : (unsigned long)sdata->data; } return (unsigned long)NULL; } BPF_CALL_2(bpf_sk_storage_delete, struct bpf_map *, map, struct sock *, sk) { if (refcount_inc_not_zero(&sk->sk_refcnt)) { int err; err = sk_storage_delete(sk, map); sock_put(sk); return err; } return -ENOENT; } static int sk_storage_map_btf_id; const struct bpf_map_ops sk_storage_map_ops = { .map_alloc_check = bpf_local_storage_map_alloc_check, .map_alloc = bpf_local_storage_map_alloc, .map_free = bpf_local_storage_map_free, .map_get_next_key = notsupp_get_next_key, .map_lookup_elem = bpf_fd_sk_storage_lookup_elem, .map_update_elem = bpf_fd_sk_storage_update_elem, .map_delete_elem = bpf_fd_sk_storage_delete_elem, .map_check_btf = bpf_local_storage_map_check_btf, .map_btf_name = "bpf_local_storage_map", .map_btf_id = &sk_storage_map_btf_id, }; const struct bpf_func_proto bpf_sk_storage_get_proto = { .func = bpf_sk_storage_get, .gpl_only = false, .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, .arg1_type = ARG_CONST_MAP_PTR, .arg2_type = ARG_PTR_TO_SOCKET, .arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL, .arg4_type = ARG_ANYTHING, }; const struct bpf_func_proto bpf_sk_storage_get_cg_sock_proto = { .func = bpf_sk_storage_get, .gpl_only = false, .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL, .arg1_type = ARG_CONST_MAP_PTR, .arg2_type = ARG_PTR_TO_CTX, /* context is 'struct sock' */ .arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL, .arg4_type = ARG_ANYTHING, }; const struct bpf_func_proto bpf_sk_storage_delete_proto = { .func = bpf_sk_storage_delete, .gpl_only = false, .ret_type = RET_INTEGER, .arg1_type = ARG_CONST_MAP_PTR, .arg2_type = ARG_PTR_TO_SOCKET, }; struct bpf_sk_storage_diag { u32 nr_maps; struct bpf_map *maps[]; }; /* The reply will be like: * INET_DIAG_BPF_SK_STORAGES (nla_nest) * SK_DIAG_BPF_STORAGE (nla_nest) * SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32) * SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit) * SK_DIAG_BPF_STORAGE (nla_nest) * SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32) * SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit) * .... */ static int nla_value_size(u32 value_size) { /* SK_DIAG_BPF_STORAGE (nla_nest) * SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32) * SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit) */ return nla_total_size(0) + nla_total_size(sizeof(u32)) + nla_total_size_64bit(value_size); } void bpf_sk_storage_diag_free(struct bpf_sk_storage_diag *diag) { u32 i; if (!diag) return; for (i = 0; i < diag->nr_maps; i++) bpf_map_put(diag->maps[i]); kfree(diag); } EXPORT_SYMBOL_GPL(bpf_sk_storage_diag_free); static bool diag_check_dup(const struct bpf_sk_storage_diag *diag, const struct bpf_map *map) { u32 i; for (i = 0; i < diag->nr_maps; i++) { if (diag->maps[i] == map) return true; } return false; } struct bpf_sk_storage_diag * bpf_sk_storage_diag_alloc(const struct nlattr *nla_stgs) { struct bpf_sk_storage_diag *diag; struct nlattr *nla; u32 nr_maps = 0; int rem, err; /* bpf_local_storage_map is currently limited to CAP_SYS_ADMIN as * the map_alloc_check() side also does. */ if (!bpf_capable()) return ERR_PTR(-EPERM); nla_for_each_nested(nla, nla_stgs, rem) { if (nla_type(nla) == SK_DIAG_BPF_STORAGE_REQ_MAP_FD) nr_maps++; } diag = kzalloc(sizeof(*diag) + sizeof(diag->maps[0]) * nr_maps, GFP_KERNEL); if (!diag) return ERR_PTR(-ENOMEM); nla_for_each_nested(nla, nla_stgs, rem) { struct bpf_map *map; int map_fd; if (nla_type(nla) != SK_DIAG_BPF_STORAGE_REQ_MAP_FD) continue; map_fd = nla_get_u32(nla); map = bpf_map_get(map_fd); if (IS_ERR(map)) { err = PTR_ERR(map); goto err_free; } if (map->map_type != BPF_MAP_TYPE_SK_STORAGE) { bpf_map_put(map); err = -EINVAL; goto err_free; } if (diag_check_dup(diag, map)) { bpf_map_put(map); err = -EEXIST; goto err_free; } diag->maps[diag->nr_maps++] = map; } return diag; err_free: bpf_sk_storage_diag_free(diag); return ERR_PTR(err); } EXPORT_SYMBOL_GPL(bpf_sk_storage_diag_alloc); static int diag_get(struct bpf_local_storage_data *sdata, struct sk_buff *skb) { struct nlattr *nla_stg, *nla_value; struct bpf_local_storage_map *smap; /* It cannot exceed max nlattr's payload */ BUILD_BUG_ON(U16_MAX - NLA_HDRLEN < BPF_LOCAL_STORAGE_MAX_VALUE_SIZE); nla_stg = nla_nest_start(skb, SK_DIAG_BPF_STORAGE); if (!nla_stg) return -EMSGSIZE; smap = rcu_dereference(sdata->smap); if (nla_put_u32(skb, SK_DIAG_BPF_STORAGE_MAP_ID, smap->map.id)) goto errout; nla_value = nla_reserve_64bit(skb, SK_DIAG_BPF_STORAGE_MAP_VALUE, smap->map.value_size, SK_DIAG_BPF_STORAGE_PAD); if (!nla_value) goto errout; if (map_value_has_spin_lock(&smap->map)) copy_map_value_locked(&smap->map, nla_data(nla_value), sdata->data, true); else copy_map_value(&smap->map, nla_data(nla_value), sdata->data); nla_nest_end(skb, nla_stg); return 0; errout: nla_nest_cancel(skb, nla_stg); return -EMSGSIZE; } static int bpf_sk_storage_diag_put_all(struct sock *sk, struct sk_buff *skb, int stg_array_type, unsigned int *res_diag_size) { /* stg_array_type (e.g. INET_DIAG_BPF_SK_STORAGES) */ unsigned int diag_size = nla_total_size(0); struct bpf_local_storage *sk_storage; struct bpf_local_storage_elem *selem; struct bpf_local_storage_map *smap; struct nlattr *nla_stgs; unsigned int saved_len; int err = 0; rcu_read_lock(); sk_storage = rcu_dereference(sk->sk_bpf_storage); if (!sk_storage || hlist_empty(&sk_storage->list)) { rcu_read_unlock(); return 0; } nla_stgs = nla_nest_start(skb, stg_array_type); if (!nla_stgs) /* Continue to learn diag_size */ err = -EMSGSIZE; saved_len = skb->len; hlist_for_each_entry_rcu(selem, &sk_storage->list, snode) { smap = rcu_dereference(SDATA(selem)->smap); diag_size += nla_value_size(smap->map.value_size); if (nla_stgs && diag_get(SDATA(selem), skb)) /* Continue to learn diag_size */ err = -EMSGSIZE; } rcu_read_unlock(); if (nla_stgs) { if (saved_len == skb->len) nla_nest_cancel(skb, nla_stgs); else nla_nest_end(skb, nla_stgs); } if (diag_size == nla_total_size(0)) { *res_diag_size = 0; return 0; } *res_diag_size = diag_size; return err; } int bpf_sk_storage_diag_put(struct bpf_sk_storage_diag *diag, struct sock *sk, struct sk_buff *skb, int stg_array_type, unsigned int *res_diag_size) { /* stg_array_type (e.g. INET_DIAG_BPF_SK_STORAGES) */ unsigned int diag_size = nla_total_size(0); struct bpf_local_storage *sk_storage; struct bpf_local_storage_data *sdata; struct nlattr *nla_stgs; unsigned int saved_len; int err = 0; u32 i; *res_diag_size = 0; /* No map has been specified. Dump all. */ if (!diag->nr_maps) return bpf_sk_storage_diag_put_all(sk, skb, stg_array_type, res_diag_size); rcu_read_lock(); sk_storage = rcu_dereference(sk->sk_bpf_storage); if (!sk_storage || hlist_empty(&sk_storage->list)) { rcu_read_unlock(); return 0; } nla_stgs = nla_nest_start(skb, stg_array_type); if (!nla_stgs) /* Continue to learn diag_size */ err = -EMSGSIZE; saved_len = skb->len; for (i = 0; i < diag->nr_maps; i++) { sdata = bpf_local_storage_lookup(sk_storage, (struct bpf_local_storage_map *)diag->maps[i], false); if (!sdata) continue; diag_size += nla_value_size(diag->maps[i]->value_size); if (nla_stgs && diag_get(sdata, skb)) /* Continue to learn diag_size */ err = -EMSGSIZE; } rcu_read_unlock(); if (nla_stgs) { if (saved_len == skb->len) nla_nest_cancel(skb, nla_stgs); else nla_nest_end(skb, nla_stgs); } if (diag_size == nla_total_size(0)) { *res_diag_size = 0; return 0; } *res_diag_size = diag_size; return err; } EXPORT_SYMBOL_GPL(bpf_sk_storage_diag_put); struct bpf_iter_seq_sk_storage_map_info { struct bpf_map *map; unsigned int bucket_id; unsigned skip_elems; }; static struct bpf_local_storage_elem * bpf_sk_storage_map_seq_find_next(struct bpf_iter_seq_sk_storage_map_info *info, struct bpf_local_storage_elem *prev_selem) { struct bpf_local_storage *sk_storage; struct bpf_local_storage_elem *selem; u32 skip_elems = info->skip_elems; struct bpf_local_storage_map *smap; u32 bucket_id = info->bucket_id; u32 i, count, n_buckets; struct bpf_local_storage_map_bucket *b; smap = (struct bpf_local_storage_map *)info->map; n_buckets = 1U << smap->bucket_log; if (bucket_id >= n_buckets) return NULL; /* try to find next selem in the same bucket */ selem = prev_selem; count = 0; while (selem) { selem = hlist_entry_safe(selem->map_node.next, struct bpf_local_storage_elem, map_node); if (!selem) { /* not found, unlock and go to the next bucket */ b = &smap->buckets[bucket_id++]; raw_spin_unlock_bh(&b->lock); skip_elems = 0; break; } sk_storage = rcu_dereference_raw(selem->local_storage); if (sk_storage) { info->skip_elems = skip_elems + count; return selem; } count++; } for (i = bucket_id; i < (1U << smap->bucket_log); i++) { b = &smap->buckets[i]; raw_spin_lock_bh(&b->lock); count = 0; hlist_for_each_entry(selem, &b->list, map_node) { sk_storage = rcu_dereference_raw(selem->local_storage); if (sk_storage && count >= skip_elems) { info->bucket_id = i; info->skip_elems = count; return selem; } count++; } raw_spin_unlock_bh(&b->lock); skip_elems = 0; } info->bucket_id = i; info->skip_elems = 0; return NULL; } static void *bpf_sk_storage_map_seq_start(struct seq_file *seq, loff_t *pos) { struct bpf_local_storage_elem *selem; selem = bpf_sk_storage_map_seq_find_next(seq->private, NULL); if (!selem) return NULL; if (*pos == 0) ++*pos; return selem; } static void *bpf_sk_storage_map_seq_next(struct seq_file *seq, void *v, loff_t *pos) { struct bpf_iter_seq_sk_storage_map_info *info = seq->private; ++*pos; ++info->skip_elems; return bpf_sk_storage_map_seq_find_next(seq->private, v); } struct bpf_iter__bpf_sk_storage_map { __bpf_md_ptr(struct bpf_iter_meta *, meta); __bpf_md_ptr(struct bpf_map *, map); __bpf_md_ptr(struct sock *, sk); __bpf_md_ptr(void *, value); }; DEFINE_BPF_ITER_FUNC(bpf_sk_storage_map, struct bpf_iter_meta *meta, struct bpf_map *map, struct sock *sk, void *value) static int __bpf_sk_storage_map_seq_show(struct seq_file *seq, struct bpf_local_storage_elem *selem) { struct bpf_iter_seq_sk_storage_map_info *info = seq->private; struct bpf_iter__bpf_sk_storage_map ctx = {}; struct bpf_local_storage *sk_storage; struct bpf_iter_meta meta; struct bpf_prog *prog; int ret = 0; meta.seq = seq; prog = bpf_iter_get_info(&meta, selem == NULL); if (prog) { ctx.meta = &meta; ctx.map = info->map; if (selem) { sk_storage = rcu_dereference_raw(selem->local_storage); ctx.sk = sk_storage->owner; ctx.value = SDATA(selem)->data; } ret = bpf_iter_run_prog(prog, &ctx); } return ret; } static int bpf_sk_storage_map_seq_show(struct seq_file *seq, void *v) { return __bpf_sk_storage_map_seq_show(seq, v); } static void bpf_sk_storage_map_seq_stop(struct seq_file *seq, void *v) { struct bpf_iter_seq_sk_storage_map_info *info = seq->private; struct bpf_local_storage_map *smap; struct bpf_local_storage_map_bucket *b; if (!v) { (void)__bpf_sk_storage_map_seq_show(seq, v); } else { smap = (struct bpf_local_storage_map *)info->map; b = &smap->buckets[info->bucket_id]; raw_spin_unlock_bh(&b->lock); } } static int bpf_iter_init_sk_storage_map(void *priv_data, struct bpf_iter_aux_info *aux) { struct bpf_iter_seq_sk_storage_map_info *seq_info = priv_data; seq_info->map = aux->map; return 0; } static int bpf_iter_attach_map(struct bpf_prog *prog, union bpf_iter_link_info *linfo, struct bpf_iter_aux_info *aux) { struct bpf_map *map; int err = -EINVAL; if (!linfo->map.map_fd) return -EBADF; map = bpf_map_get_with_uref(linfo->map.map_fd); if (IS_ERR(map)) return PTR_ERR(map); if (map->map_type != BPF_MAP_TYPE_SK_STORAGE) goto put_map; if (prog->aux->max_rdonly_access > map->value_size) { err = -EACCES; goto put_map; } aux->map = map; return 0; put_map: bpf_map_put_with_uref(map); return err; } static void bpf_iter_detach_map(struct bpf_iter_aux_info *aux) { bpf_map_put_with_uref(aux->map); } static const struct seq_operations bpf_sk_storage_map_seq_ops = { .start = bpf_sk_storage_map_seq_start, .next = bpf_sk_storage_map_seq_next, .stop = bpf_sk_storage_map_seq_stop, .show = bpf_sk_storage_map_seq_show, }; static const struct bpf_iter_seq_info iter_seq_info = { .seq_ops = &bpf_sk_storage_map_seq_ops, .init_seq_private = bpf_iter_init_sk_storage_map, .fini_seq_private = NULL, .seq_priv_size = sizeof(struct bpf_iter_seq_sk_storage_map_info), }; static struct bpf_iter_reg bpf_sk_storage_map_reg_info = { .target = "bpf_sk_storage_map", .attach_target = bpf_iter_attach_map, .detach_target = bpf_iter_detach_map, .show_fdinfo = bpf_iter_map_show_fdinfo, .fill_link_info = bpf_iter_map_fill_link_info, .ctx_arg_info_size = 2, .ctx_arg_info = { { offsetof(struct bpf_iter__bpf_sk_storage_map, sk), PTR_TO_BTF_ID_OR_NULL }, { offsetof(struct bpf_iter__bpf_sk_storage_map, value), PTR_TO_RDWR_BUF_OR_NULL }, }, .seq_info = &iter_seq_info, }; static int __init bpf_sk_storage_map_iter_init(void) { bpf_sk_storage_map_reg_info.ctx_arg_info[0].btf_id = btf_sock_ids[BTF_SOCK_TYPE_SOCK]; return bpf_iter_reg_target(&bpf_sk_storage_map_reg_info); } late_initcall(bpf_sk_storage_map_iter_init);