diff options
| author | Teng Qin | 2017-04-24 19:00:37 -0700 |
|---|---|---|
| committer | David S. Miller | 2017-04-25 11:57:45 -0400 |
| commit | 8fe45924387be6b5c1be59a7eb330790c61d5d10 (patch) | |
| tree | 1879f4fd4d14907155b1ebb2fd85ff26aa89ebbe /kernel | |
| parent | 472ecf084a7687347f79720c83881c07407bfd8b (diff) | |
bpf: map_get_next_key to return first key on NULL
When iterating through a map, we need to find a key that does not exist
in the map so map_get_next_key will give us the first key of the map.
This often requires a lot of guessing in production systems.
This patch makes map_get_next_key return the first key when the key
pointer in the parameter is NULL.
Signed-off-by: Teng Qin <qinteng@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/arraymap.c | 2 | ||||
| -rw-r--r-- | kernel/bpf/hashtab.c | 9 | ||||
| -rw-r--r-- | kernel/bpf/syscall.c | 20 |
3 files changed, 18 insertions, 13 deletions
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index ec621df5a97a..5e00b2333c26 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -182,7 +182,7 @@ int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value) static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key) { struct bpf_array *array = container_of(map, struct bpf_array, map); - u32 index = *(u32 *)key; + u32 index = key ? *(u32 *)key : U32_MAX; u32 *next = (u32 *)next_key; if (index >= array->map.max_entries) { diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index bc80c038e430..004334ea13ba 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -540,12 +540,15 @@ static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key) struct hlist_nulls_head *head; struct htab_elem *l, *next_l; u32 hash, key_size; - int i; + int i = 0; WARN_ON_ONCE(!rcu_read_lock_held()); key_size = map->key_size; + if (!key) + goto find_first_elem; + hash = htab_map_hash(key, key_size); head = select_bucket(htab, hash); @@ -553,10 +556,8 @@ static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key) /* lookup the key */ l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets); - if (!l) { - i = 0; + if (!l) goto find_first_elem; - } /* key was found, get next key in the same bucket */ next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_next_rcu(&l->hash_node)), diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index b89288e2b589..13642c73dca0 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -536,14 +536,18 @@ static int map_get_next_key(union bpf_attr *attr) if (IS_ERR(map)) return PTR_ERR(map); - err = -ENOMEM; - key = kmalloc(map->key_size, GFP_USER); - if (!key) - goto err_put; - - err = -EFAULT; - if (copy_from_user(key, ukey, map->key_size) != 0) - goto free_key; + if (ukey) { + err = -ENOMEM; + key = kmalloc(map->key_size, GFP_USER); + if (!key) + goto err_put; + + err = -EFAULT; + if (copy_from_user(key, ukey, map->key_size) != 0) + goto free_key; + } else { + key = NULL; + } err = -ENOMEM; next_key = kmalloc(map->key_size, GFP_USER); |