diff options
| -rw-r--r-- | include/linux/bpf.h | 2 | ||||
| -rw-r--r-- | include/linux/bpf_types.h | 1 | ||||
| -rw-r--r-- | include/net/bpf_sk_storage.h | 13 | ||||
| -rw-r--r-- | include/net/sock.h | 5 | ||||
| -rw-r--r-- | include/uapi/linux/bpf.h | 44 | ||||
| -rw-r--r-- | kernel/bpf/syscall.c | 3 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 27 | ||||
| -rw-r--r-- | net/bpf/test_run.c | 2 | ||||
| -rw-r--r-- | net/core/Makefile | 1 | ||||
| -rw-r--r-- | net/core/bpf_sk_storage.c | 804 | ||||
| -rw-r--r-- | net/core/filter.c | 12 | ||||
| -rw-r--r-- | net/core/sock.c | 5 |
12 files changed, 914 insertions, 5 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index cd6341eabd74..9a21848fdb07 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -184,6 +184,7 @@ enum bpf_arg_type { ARG_PTR_TO_MAP_KEY, /* pointer to stack used as map key */ ARG_PTR_TO_MAP_VALUE, /* pointer to stack used as map value */ ARG_PTR_TO_UNINIT_MAP_VALUE, /* pointer to valid memory used to store a map value */ + ARG_PTR_TO_MAP_VALUE_OR_NULL, /* pointer to stack used as map value or NULL */ /* the following constraints used to prototype bpf_memcmp() and other * functions that access data on eBPF program stack @@ -204,6 +205,7 @@ enum bpf_arg_type { ARG_PTR_TO_SOCK_COMMON, /* pointer to sock_common */ ARG_PTR_TO_INT, /* pointer to int */ ARG_PTR_TO_LONG, /* pointer to long */ + ARG_PTR_TO_SOCKET, /* pointer to bpf_sock (fullsock) */ }; /* type of values returned from helper functions */ diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h index a10d37bce364..5a9975678d6f 100644 --- a/include/linux/bpf_types.h +++ b/include/linux/bpf_types.h @@ -61,6 +61,7 @@ BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY_OF_MAPS, array_of_maps_map_ops) BPF_MAP_TYPE(BPF_MAP_TYPE_HASH_OF_MAPS, htab_of_maps_map_ops) #ifdef CONFIG_NET BPF_MAP_TYPE(BPF_MAP_TYPE_DEVMAP, dev_map_ops) +BPF_MAP_TYPE(BPF_MAP_TYPE_SK_STORAGE, sk_storage_map_ops) #if defined(CONFIG_BPF_STREAM_PARSER) BPF_MAP_TYPE(BPF_MAP_TYPE_SOCKMAP, sock_map_ops) BPF_MAP_TYPE(BPF_MAP_TYPE_SOCKHASH, sock_hash_ops) diff --git a/include/net/bpf_sk_storage.h b/include/net/bpf_sk_storage.h new file mode 100644 index 000000000000..b9dcb02e756b --- /dev/null +++ b/include/net/bpf_sk_storage.h @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (c) 2019 Facebook */ +#ifndef _BPF_SK_STORAGE_H +#define _BPF_SK_STORAGE_H + +struct sock; + +void bpf_sk_storage_free(struct sock *sk); + +extern const struct bpf_func_proto bpf_sk_storage_get_proto; +extern const struct bpf_func_proto bpf_sk_storage_delete_proto; + +#endif /* _BPF_SK_STORAGE_H */ diff --git a/include/net/sock.h b/include/net/sock.h index 784cd19d5ff7..4d208c0f9c14 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -236,6 +236,8 @@ struct sock_common { /* public: */ }; +struct bpf_sk_storage; + /** * struct sock - network layer representation of sockets * @__sk_common: shared layout with inet_timewait_sock @@ -510,6 +512,9 @@ struct sock { #endif void (*sk_destruct)(struct sock *sk); struct sock_reuseport __rcu *sk_reuseport_cb; +#ifdef CONFIG_BPF_SYSCALL + struct bpf_sk_storage __rcu *sk_bpf_storage; +#endif struct rcu_head sk_rcu; }; diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index f7fa7a34a62d..72336bac7573 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -133,6 +133,7 @@ enum bpf_map_type { BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE, BPF_MAP_TYPE_QUEUE, BPF_MAP_TYPE_STACK, + BPF_MAP_TYPE_SK_STORAGE, }; /* Note that tracing related programs such as @@ -2630,6 +2631,42 @@ union bpf_attr { * was provided. * * **-ERANGE** if resulting value was out of range. + * + * void *bpf_sk_storage_get(struct bpf_map *map, struct bpf_sock *sk, void *value, u64 flags) + * Description + * Get a bpf-local-storage from a sk. + * + * Logically, it could be thought of getting the value from + * a *map* with *sk* as the **key**. From this + * perspective, the usage is not much different from + * **bpf_map_lookup_elem(map, &sk)** except this + * helper enforces the key must be a **bpf_fullsock()** + * and the map must be a BPF_MAP_TYPE_SK_STORAGE also. + * + * Underneath, the value is stored locally at *sk* instead of + * the map. The *map* is used as the bpf-local-storage **type**. + * The bpf-local-storage **type** (i.e. the *map*) is searched + * against all bpf-local-storages residing at sk. + * + * An optional *flags* (BPF_SK_STORAGE_GET_F_CREATE) can be + * used such that a new bpf-local-storage will be + * created if one does not exist. *value* can be used + * together with BPF_SK_STORAGE_GET_F_CREATE to specify + * the initial value of a bpf-local-storage. If *value* is + * NULL, the new bpf-local-storage will be zero initialized. + * Return + * A bpf-local-storage pointer is returned on success. + * + * **NULL** if not found or there was an error in adding + * a new bpf-local-storage. + * + * int bpf_sk_storage_delete(struct bpf_map *map, struct bpf_sock *sk) + * Description + * Delete a bpf-local-storage from a sk. + * Return + * 0 on success. + * + * **-ENOENT** if the bpf-local-storage cannot be found. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -2738,7 +2775,9 @@ union bpf_attr { FN(sysctl_get_new_value), \ FN(sysctl_set_new_value), \ FN(strtol), \ - FN(strtoul), + FN(strtoul), \ + FN(sk_storage_get), \ + FN(sk_storage_delete), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call @@ -2814,6 +2853,9 @@ enum bpf_func_id { /* BPF_FUNC_sysctl_get_name flags. */ #define BPF_F_SYSCTL_BASE_NAME (1ULL << 0) +/* BPF_FUNC_sk_storage_get flags */ +#define BPF_SK_STORAGE_GET_F_CREATE (1ULL << 0) + /* Mode for BPF_FUNC_skb_adjust_room helper. */ enum bpf_adj_room_mode { BPF_ADJ_ROOM_NET, diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index ae141e745f92..ad3ccf82f31d 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -526,7 +526,8 @@ static int map_check_btf(struct bpf_map *map, const struct btf *btf, return -EACCES; if (map->map_type != BPF_MAP_TYPE_HASH && map->map_type != BPF_MAP_TYPE_ARRAY && - map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE) + map->map_type != BPF_MAP_TYPE_CGROUP_STORAGE && + map->map_type != BPF_MAP_TYPE_SK_STORAGE) return -ENOTSUPP; if (map->spin_lock_off + sizeof(struct bpf_spin_lock) > map->value_size) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 2ef442c62c0e..271717246af3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2543,10 +2543,15 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno, if (arg_type == ARG_PTR_TO_MAP_KEY || arg_type == ARG_PTR_TO_MAP_VALUE || - arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE) { + arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE || + arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL) { expected_type = PTR_TO_STACK; - if (!type_is_pkt_pointer(type) && type != PTR_TO_MAP_VALUE && - type != expected_type) + if (register_is_null(reg) && + arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL) + /* final test in check_stack_boundary() */; + else if (!type_is_pkt_pointer(type) && + type != PTR_TO_MAP_VALUE && + type != expected_type) goto err_type; } else if (arg_type == ARG_CONST_SIZE || arg_type == ARG_CONST_SIZE_OR_ZERO) { @@ -2578,6 +2583,10 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno, } meta->ref_obj_id = reg->ref_obj_id; } + } else if (arg_type == ARG_PTR_TO_SOCKET) { + expected_type = PTR_TO_SOCKET; + if (type != expected_type) + goto err_type; } else if (arg_type == ARG_PTR_TO_SPIN_LOCK) { if (meta->func_id == BPF_FUNC_spin_lock) { if (process_spin_lock(env, regno, true)) @@ -2635,6 +2644,8 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 regno, meta->map_ptr->key_size, false, NULL); } else if (arg_type == ARG_PTR_TO_MAP_VALUE || + (arg_type == ARG_PTR_TO_MAP_VALUE_OR_NULL && + !register_is_null(reg)) || arg_type == ARG_PTR_TO_UNINIT_MAP_VALUE) { /* bpf_map_xxx(..., map_ptr, ..., value) call: * check [value, value + map->value_size) validity @@ -2784,6 +2795,11 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, func_id != BPF_FUNC_map_push_elem) goto error; break; + case BPF_MAP_TYPE_SK_STORAGE: + if (func_id != BPF_FUNC_sk_storage_get && + func_id != BPF_FUNC_sk_storage_delete) + goto error; + break; default: break; } @@ -2847,6 +2863,11 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, map->map_type != BPF_MAP_TYPE_STACK) goto error; break; + case BPF_FUNC_sk_storage_get: + case BPF_FUNC_sk_storage_delete: + if (map->map_type != BPF_MAP_TYPE_SK_STORAGE) + goto error; + break; default: break; } diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 6c4694ae4241..33e0dc168c16 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -10,6 +10,7 @@ #include <linux/etherdevice.h> #include <linux/filter.h> #include <linux/sched/signal.h> +#include <net/bpf_sk_storage.h> #include <net/sock.h> #include <net/tcp.h> @@ -335,6 +336,7 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr, sizeof(struct __sk_buff)); out: kfree_skb(skb); + bpf_sk_storage_free(sk); kfree(sk); kfree(ctx); return ret; diff --git a/net/core/Makefile b/net/core/Makefile index f97d6254e564..a104dc8faafc 100644 --- a/net/core/Makefile +++ b/net/core/Makefile @@ -34,3 +34,4 @@ obj-$(CONFIG_HWBM) += hwbm.o obj-$(CONFIG_NET_DEVLINK) += devlink.o obj-$(CONFIG_GRO_CELLS) += gro_cells.o obj-$(CONFIG_FAILOVER) += failover.o +obj-$(CONFIG_BPF_SYSCALL) += bpf_sk_storage.o diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c new file mode 100644 index 000000000000..a8e9ac71b22d --- /dev/null +++ b/net/core/bpf_sk_storage.c @@ -0,0 +1,804 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2019 Facebook */ +#include <linux/rculist.h> +#include <linux/list.h> +#include <linux/hash.h> +#include <linux/types.h> +#include <linux/spinlock.h> +#include <linux/bpf.h> +#include <net/bpf_sk_storage.h> +#include <net/sock.h> +#include <uapi/linux/btf.h> + +static atomic_t cache_idx; + +struct bucket { + struct hlist_head list; + raw_spinlock_t lock; +}; + +/* Thp map is not the primary owner of a bpf_sk_storage_elem. + * Instead, the sk->sk_bpf_storage is. + * + * The map (bpf_sk_storage_map) is for two purposes + * 1. Define the size of the "sk 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 sk, the "bpf_map" pointer is actually used + * as the "key" to search in the list of elem in + * sk->sk_bpf_storage. + * + * Hence, consider sk->sk_bpf_storage is the mini-map + * with the "bpf_map" pointer as the searching key. + */ +struct bpf_sk_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 bucket *buckets; + u32 bucket_log; + u16 elem_size; + u16 cache_idx; +}; + +struct bpf_sk_storage_data { + /* smap is used as the searching key when looking up + * from sk->sk_bpf_storage. + * + * Put it in the same cacheline as the data to minimize + * the number of cachelines access during the cache hit case. + */ + struct bpf_sk_storage_map __rcu *smap; + u8 data[0] __aligned(8); +}; + +/* Linked to bpf_sk_storage and bpf_sk_storage_map */ +struct bpf_sk_storage_elem { + struct hlist_node map_node; /* Linked to bpf_sk_storage_map */ + struct hlist_node snode; /* Linked to bpf_sk_storage */ + struct bpf_sk_storage __rcu *sk_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_sk_storage_data sdata ____cacheline_aligned; +}; + +#define SELEM(_SDATA) container_of((_SDATA), struct bpf_sk_storage_elem, sdata) +#define SDATA(_SELEM) (&(_SELEM)->sdata) +#define BPF_SK_STORAGE_CACHE_SIZE 16 + +struct bpf_sk_storage { + struct bpf_sk_storage_data __rcu *cache[BPF_SK_STORAGE_CACHE_SIZE]; + struct hlist_head list; /* List of bpf_sk_storage_elem */ + struct sock *sk; /* The sk that owns the the above "list" of + * bpf_sk_storage_elem. + */ + struct rcu_head rcu; + raw_spinlock_t lock; /* Protect adding/removing from the "list" */ +}; + +static struct bucket *select_bucket(struct bpf_sk_storage_map *smap, + struct bpf_sk_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_sk(const struct bpf_sk_storage_elem *selem) +{ + return !hlist_unhashed(&selem->snode); +} + +static bool selem_linked_to_map(const struct bpf_sk_storage_elem *selem) +{ + return !hlist_unhashed(&selem->map_node); +} + +static struct bpf_sk_storage_elem *selem_alloc(struct bpf_sk_storage_map *smap, + struct sock *sk, void *value, + bool charge_omem) +{ + struct bpf_sk_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; +} + +/* sk_storage->lock must be held and selem->sk_storage == sk_storage. + * The caller must ensure selem->smap is still valid to be + * dereferenced for its smap->elem_size and smap->cache_idx. + */ +static bool __selem_unlink_sk(struct bpf_sk_storage *sk_storage, + struct bpf_sk_storage_elem *selem, + bool uncharge_omem) +{ + struct bpf_sk_storage_map *smap; + bool free_sk_storage; + struct sock *sk; + + smap = rcu_dereference(SDATA(selem)->smap); + sk = sk_storage->sk; + + /* All uncharging on sk->sk_omem_alloc must be done first. + * sk may be freed once the last selem is unlinked from sk_storage. + */ + if (uncharge_omem) + atomic_sub(smap->elem_size, &sk->sk_omem_alloc); + + free_sk_storage = hlist_is_singular_node(&selem->snode, + &sk_storage->list); + if (free_sk_storage) { + atomic_sub(sizeof(struct bpf_sk_storage), &sk->sk_omem_alloc); + sk_storage->sk = NULL; + /* After this RCU_INIT, sk may be freed and cannot be used */ + RCU_INIT_POINTER(sk->sk_bpf_storage, NULL); + + /* sk_storage is not freed now. sk_storage->lock is + * still held and raw_spin_unlock_bh(&sk_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(sk_storage, rcu) is done + * after the raw_spin_unlock_bh(&sk_storage->lock). + * + * Hence, a "bool free_sk_storage" is returned + * to the caller which then calls the kfree_rcu() + * after unlock. + */ + } + hlist_del_init_rcu(&selem->snode); + if (rcu_access_pointer(sk_storage->cache[smap->cache_idx]) == + SDATA(selem)) + RCU_INIT_POINTER(sk_storage->cache[smap->cache_idx], NULL); + + kfree_rcu(selem, rcu); + + return free_sk_storage; +} + +static void selem_unlink_sk(struct bpf_sk_storage_elem *selem) +{ + struct bpf_sk_storage *sk_storage; + bool free_sk_storage = false; + + if (unlikely(!selem_linked_to_sk(selem))) + /* selem has already been unlinked from sk */ + return; + + sk_storage = rcu_dereference(selem->sk_storage); + raw_spin_lock_bh(&sk_storage->lock); + if (likely(selem_linked_to_sk(selem))) + free_sk_storage = __selem_unlink_sk(sk_storage, selem, true); + raw_spin_unlock_bh(&sk_storage->lock); + + if (free_sk_storage) + kfree_rcu(sk_storage, rcu); +} + +/* sk_storage->lock must be held and sk_storage->list cannot be empty */ +static void __selem_link_sk(struct bpf_sk_storage *sk_storage, + struct bpf_sk_storage_elem *selem) +{ + RCU_INIT_POINTER(selem->sk_storage, sk_storage); + hlist_add_head(&selem->snode, &sk_storage->list); +} + +static void selem_unlink_map(struct bpf_sk_storage_elem *selem) +{ + struct bpf_sk_storage_map *smap; + struct 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 selem_link_map(struct bpf_sk_storage_map *smap, + struct bpf_sk_storage_elem *selem) +{ + struct 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 selem_unlink(struct bpf_sk_storage_elem *selem) +{ + /* Always unlink from map before unlinking from sk_storage + * because selem will be freed after successfully unlinked from + * the sk_storage. + */ + selem_unlink_map(selem); + selem_unlink_sk(selem); +} + +static struct bpf_sk_storage_data * +__sk_storage_lookup(struct bpf_sk_storage *sk_storage, + struct bpf_sk_storage_map *smap, + bool cacheit_lockit) +{ + struct bpf_sk_storage_data *sdata; + struct bpf_sk_storage_elem *selem; + + /* Fast path (cache hit) */ + sdata = rcu_dereference(sk_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, &sk_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 __sk_storage_lookup(). + */ + raw_spin_lock_bh(&sk_storage->lock); + if (selem_linked_to_sk(selem)) + rcu_assign_pointer(sk_storage->cache[smap->cache_idx], + sdata); + raw_spin_unlock_bh(&sk_storage->lock); + } + + return sdata; +} + +static struct bpf_sk_storage_data * +sk_storage_lookup(struct sock *sk, struct bpf_map *map, bool cacheit_lockit) +{ + struct bpf_sk_storage *sk_storage; + struct bpf_sk_storage_map *smap; + + sk_storage = rcu_dereference(sk->sk_bpf_storage); + if (!sk_storage) + return NULL; + + smap = (struct bpf_sk_storage_map *)map; + return __sk_storage_lookup(sk_storage, smap, cacheit_lockit); +} + +static int check_flags(const struct bpf_sk_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_sk_storage_map *smap, + struct bpf_sk_storage_elem *first_selem) +{ + struct bpf_sk_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->sk = sk; + + __selem_link_sk(sk_storage, first_selem); + 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_sk_storage **)&sk->sk_bpf_storage, + NULL, sk_storage); + if (unlikely(prev_sk_storage)) { + 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_sk_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_sk_storage_data *sk_storage_update(struct sock *sk, + struct bpf_map *map, + void *value, + u64 map_flags) +{ + struct bpf_sk_storage_data *old_sdata = NULL; + struct bpf_sk_storage_elem *selem; + struct bpf_sk_storage *sk_storage; + struct bpf_sk_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_sk_storage_map *)map; + sk_storage = rcu_dereference(sk->sk_bpf_storage); + if (!sk_storage || hlist_empty(&sk_storage->list)) { + /* Very first elem for this sk */ + err = check_flags(NULL, map_flags); + if (err) + return ERR_PTR(err); + + selem = 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 sk_storage->lock + * and changing the lists. + */ + old_sdata = __sk_storage_lookup(sk_storage, smap, false); + err = check_flags(old_sdata, map_flags); + if (err) + return ERR_PTR(err); + if (old_sdata && selem_linked_to_sk(SELEM(old_sdata))) { + copy_map_value_locked(map, old_sdata->data, + value, false); + return old_sdata; + } + } + + raw_spin_lock_bh(&sk_storage->lock); + + /* Recheck sk_storage->list under sk_storage->lock */ + if (unlikely(hlist_empty(&sk_storage->list))) { + /* A parallel del is happening and sk_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 = __sk_storage_lookup(sk_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; + } + + /* sk_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 __selem_unlink_sk(). + */ + selem = selem_alloc(smap, sk, value, !old_sdata); + if (!selem) { + err = -ENOMEM; + goto unlock_err; + } + + /* First, link the new selem to the map */ + selem_link_map(smap, selem); + + /* Second, link (and publish) the new selem to sk_storage */ + __selem_link_sk(sk_storage, selem); + + /* Third, remove old selem, SELEM(old_sdata) */ + if (old_sdata) { + selem_unlink_map(SELEM(old_sdata)); + __selem_unlink_sk(sk_storage, SELEM(old_sdata), false); + } + +unlock: + raw_spin_unlock_bh(&sk_storage->lock); + return SDATA(selem); + +unlock_err: + raw_spin_unlock_bh(&sk_storage->lock); + return ERR_PTR(err); +} + +static int sk_storage_delete(struct sock *sk, struct bpf_map *map) +{ + struct bpf_sk_storage_data *sdata; + + sdata = sk_storage_lookup(sk, map, false); + if (!sdata) + return -ENOENT; + + selem_unlink(SELEM(sdata)); + + return 0; +} + +/* Called by __sk_destruct() */ +void bpf_sk_storage_free(struct sock *sk) +{ + struct bpf_sk_storage_elem *selem; + struct bpf_sk_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_sk_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. + */ + selem_unlink_map(selem); + free_sk_storage = __selem_unlink_sk(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_sk_storage_map_free(struct bpf_map *map) +{ + struct bpf_sk_storage_elem *selem; + struct bpf_sk_storage_map *smap; + struct bucket *b; + unsigned int i; + + smap = (struct bpf_sk_storage_map *)map; + + 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 sk->sk_bpf_storage or to the map bucket's list. + * + * The elem of this map can be cleaned up here + * or + * 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_sk_storage_elem, + map_node))) { + selem_unlink(selem); + cond_resched_rcu(); + } + rcu_read_unlock(); + } + + /* bpf_sk_storage_free() may still need to access the map. + * e.g. bpf_sk_storage_free() has unlinked selem from the map + * which then made the above while((selem = ...)) loop + * exited immediately. + * + * However, the bpf_sk_storage_free() still needs to access + * the smap->elem_size to do the uncharging in + * __selem_unlink_sk(). + * + * Hence, wait another rcu grace period for the + * bpf_sk_storage_free() to finish. + */ + synchronize_rcu(); + + kvfree(smap->buckets); + kfree(map); +} + +static int bpf_sk_storage_map_alloc_check(union bpf_attr *attr) +{ + if (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 (!capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (attr->value_size >= KMALLOC_MAX_SIZE - + MAX_BPF_STACK - sizeof(struct bpf_sk_storage_elem) || + /* U16_MAX is much more than enough for sk local storage + * considering a tcp_sock is ~2k. + */ + attr->value_size > U16_MAX - sizeof(struct bpf_sk_storage_elem)) + return -E2BIG; + + return 0; +} + +static struct bpf_map *bpf_sk_storage_map_alloc(union bpf_attr *attr) +{ + struct bpf_sk_storage_map *smap; + unsigned int i; + u32 nbuckets; + u64 cost; + + smap = kzalloc(sizeof(*smap), GFP_USER | __GFP_NOWARN); + if (!smap) + return ERR_PTR(-ENOMEM); + bpf_map_init_from_attr(&smap->map, attr); + + smap->bucket_log = ilog2(roundup_pow_of_two(num_possible_cpus())); + nbuckets = 1U << smap->bucket_log; + smap->buckets = kvcalloc(sizeof(*smap->buckets), nbuckets, + GFP_USER | __GFP_NOWARN); + if (!smap->buckets) { + kfree(smap); + return ERR_PTR(-ENOMEM); + } + cost = sizeof(*smap->buckets) * nbuckets + sizeof(*smap); + + 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_sk_storage_elem) + attr->value_size; + smap->cache_idx = (unsigned int)atomic_inc_return(&cache_idx) % + BPF_SK_STORAGE_CACHE_SIZE; + smap->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT; + + return &smap->map; +} + +static int notsupp_get_next_key(struct bpf_map *map, void *key, + void *next_key) +{ + return -ENOTSUPP; +} + +static int bpf_sk_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_sk_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_sk_storage_data *sdata; + struct socket *sock; + int fd, err; + + fd = *(int *)key; + sock = sockfd_lookup(fd, &err); + if (sock) { + sdata = sk_storage_update(sock->sk, map, value, map_flags); + sockfd_put(sock); + return IS_ERR(sdata) ? PTR_ERR(sdata) : 0; + } + + 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; +} + +BPF_CALL_4(bpf_sk_storage_get, struct bpf_map *, map, struct sock *, sk, + void *, value, u64, flags) +{ + struct bpf_sk_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 = sk_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; +} + +const struct bpf_map_ops sk_storage_map_ops = { + .map_alloc_check = bpf_sk_storage_map_alloc_check, + .map_alloc = bpf_sk_storage_map_alloc, + .map_free = bpf_sk_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_sk_storage_map_check_btf, +}; + +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_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, +}; diff --git a/net/core/filter.c b/net/core/filter.c index 2f88baf39cc2..27b0dc01dc3f 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -75,6 +75,7 @@ #include <net/seg6_local.h> #include <net/lwtunnel.h> #include <net/ipv6_stubs.h> +#include <net/bpf_sk_storage.h> /** * sk_filter_trim_cap - run a packet through a socket filter @@ -5903,6 +5904,9 @@ sk_filter_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) } } +const struct bpf_func_proto bpf_sk_storage_get_proto __weak; +const struct bpf_func_proto bpf_sk_storage_delete_proto __weak; + static const struct bpf_func_proto * cg_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { @@ -5911,6 +5915,10 @@ cg_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_get_local_storage_proto; case BPF_FUNC_sk_fullsock: return &bpf_sk_fullsock_proto; + case BPF_FUNC_sk_storage_get: + return &bpf_sk_storage_get_proto; + case BPF_FUNC_sk_storage_delete: + return &bpf_sk_storage_delete_proto; #ifdef CONFIG_INET case BPF_FUNC_tcp_sock: return &bpf_tcp_sock_proto; @@ -5992,6 +6000,10 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_skb_fib_lookup_proto; case BPF_FUNC_sk_fullsock: return &bpf_sk_fullsock_proto; + case BPF_FUNC_sk_storage_get: + return &bpf_sk_storage_get_proto; + case BPF_FUNC_sk_storage_delete: + return &bpf_sk_storage_delete_proto; #ifdef CONFIG_XFRM case BPF_FUNC_skb_get_xfrm_state: return &bpf_skb_get_xfrm_state_proto; diff --git a/net/core/sock.c b/net/core/sock.c index 443b98d05f1e..9773be724aa9 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -137,6 +137,7 @@ #include <linux/filter.h> #include <net/sock_reuseport.h> +#include <net/bpf_sk_storage.h> #include <trace/events/sock.h> @@ -1709,6 +1710,10 @@ static void __sk_destruct(struct rcu_head *head) sock_disable_timestamp(sk, SK_FLAGS_TIMESTAMP); +#ifdef CONFIG_BPF_SYSCALL + bpf_sk_storage_free(sk); +#endif + if (atomic_read(&sk->sk_omem_alloc)) pr_debug("%s: optmem leakage (%d bytes) detected\n", __func__, atomic_read(&sk->sk_omem_alloc)); |