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>
This commit is contained in:
parent
472ecf084a
commit
8fe4592438
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@ -321,11 +321,14 @@ TRACE_EVENT(bpf_map_next_key,
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__dynamic_array(u8, key, map->key_size)
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__dynamic_array(u8, nxt, map->key_size)
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__field(bool, key_trunc)
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__field(bool, key_null)
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__field(int, ufd)
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),
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TP_fast_assign(
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memcpy(__get_dynamic_array(key), key, map->key_size);
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if (key)
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memcpy(__get_dynamic_array(key), key, map->key_size);
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__entry->key_null = !key;
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memcpy(__get_dynamic_array(nxt), key_next, map->key_size);
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__entry->type = map->map_type;
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__entry->key_len = min(map->key_size, 16U);
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@ -336,8 +339,9 @@ TRACE_EVENT(bpf_map_next_key,
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TP_printk("map type=%s ufd=%d key=[%s%s] next=[%s%s]",
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__print_symbolic(__entry->type, __MAP_TYPE_SYM_TAB),
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__entry->ufd,
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__print_hex(__get_dynamic_array(key), __entry->key_len),
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__entry->key_trunc ? " ..." : "",
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__entry->key_null ? "NULL" : __print_hex(__get_dynamic_array(key),
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__entry->key_len),
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__entry->key_trunc && !__entry->key_null ? " ..." : "",
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__print_hex(__get_dynamic_array(nxt), __entry->key_len),
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__entry->key_trunc ? " ..." : "")
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);
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@ -182,7 +182,7 @@ int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
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static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
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{
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struct bpf_array *array = container_of(map, struct bpf_array, map);
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u32 index = *(u32 *)key;
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u32 index = key ? *(u32 *)key : U32_MAX;
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u32 *next = (u32 *)next_key;
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if (index >= array->map.max_entries) {
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@ -540,12 +540,15 @@ static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
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struct hlist_nulls_head *head;
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struct htab_elem *l, *next_l;
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u32 hash, key_size;
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int i;
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int i = 0;
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WARN_ON_ONCE(!rcu_read_lock_held());
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key_size = map->key_size;
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if (!key)
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goto find_first_elem;
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hash = htab_map_hash(key, key_size);
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head = select_bucket(htab, hash);
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@ -553,10 +556,8 @@ static int htab_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
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/* lookup the key */
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l = lookup_nulls_elem_raw(head, hash, key, key_size, htab->n_buckets);
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if (!l) {
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i = 0;
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if (!l)
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goto find_first_elem;
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}
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/* key was found, get next key in the same bucket */
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next_l = hlist_nulls_entry_safe(rcu_dereference_raw(hlist_nulls_next_rcu(&l->hash_node)),
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@ -536,14 +536,18 @@ static int map_get_next_key(union bpf_attr *attr)
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if (IS_ERR(map))
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return PTR_ERR(map);
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err = -ENOMEM;
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key = kmalloc(map->key_size, GFP_USER);
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if (!key)
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goto err_put;
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if (ukey) {
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err = -ENOMEM;
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key = kmalloc(map->key_size, GFP_USER);
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if (!key)
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goto err_put;
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err = -EFAULT;
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if (copy_from_user(key, ukey, map->key_size) != 0)
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goto free_key;
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err = -EFAULT;
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if (copy_from_user(key, ukey, map->key_size) != 0)
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goto free_key;
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} else {
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key = NULL;
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}
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err = -ENOMEM;
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next_key = kmalloc(map->key_size, GFP_USER);
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@ -28,7 +28,7 @@ static int map_flags;
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static void test_hashmap(int task, void *data)
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{
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long long key, next_key, value;
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long long key, next_key, first_key, value;
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int fd;
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fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(key), sizeof(value),
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@ -89,10 +89,13 @@ static void test_hashmap(int task, void *data)
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assert(bpf_map_delete_elem(fd, &key) == -1 && errno == ENOENT);
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/* Iterate over two elements. */
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assert(bpf_map_get_next_key(fd, NULL, &first_key) == 0 &&
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(first_key == 1 || first_key == 2));
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assert(bpf_map_get_next_key(fd, &key, &next_key) == 0 &&
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(next_key == 1 || next_key == 2));
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(next_key == first_key));
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assert(bpf_map_get_next_key(fd, &next_key, &next_key) == 0 &&
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(next_key == 1 || next_key == 2));
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(next_key == 1 || next_key == 2) &&
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(next_key != first_key));
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assert(bpf_map_get_next_key(fd, &next_key, &next_key) == -1 &&
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errno == ENOENT);
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@ -105,6 +108,8 @@ static void test_hashmap(int task, void *data)
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key = 0;
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/* Check that map is empty. */
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assert(bpf_map_get_next_key(fd, NULL, &next_key) == -1 &&
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errno == ENOENT);
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assert(bpf_map_get_next_key(fd, &key, &next_key) == -1 &&
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errno == ENOENT);
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@ -133,7 +138,7 @@ static void test_hashmap_percpu(int task, void *data)
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{
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unsigned int nr_cpus = bpf_num_possible_cpus();
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long long value[nr_cpus];
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long long key, next_key;
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long long key, next_key, first_key;
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int expected_key_mask = 0;
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int fd, i;
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@ -193,7 +198,13 @@ static void test_hashmap_percpu(int task, void *data)
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assert(bpf_map_delete_elem(fd, &key) == -1 && errno == ENOENT);
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/* Iterate over two elements. */
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assert(bpf_map_get_next_key(fd, NULL, &first_key) == 0 &&
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((expected_key_mask & first_key) == first_key));
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while (!bpf_map_get_next_key(fd, &key, &next_key)) {
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if (first_key) {
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assert(next_key == first_key);
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first_key = 0;
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}
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assert((expected_key_mask & next_key) == next_key);
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expected_key_mask &= ~next_key;
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@ -219,6 +230,8 @@ static void test_hashmap_percpu(int task, void *data)
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key = 0;
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/* Check that map is empty. */
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assert(bpf_map_get_next_key(fd, NULL, &next_key) == -1 &&
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errno == ENOENT);
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assert(bpf_map_get_next_key(fd, &key, &next_key) == -1 &&
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errno == ENOENT);
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@ -264,6 +277,8 @@ static void test_arraymap(int task, void *data)
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assert(bpf_map_lookup_elem(fd, &key, &value) == -1 && errno == ENOENT);
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/* Iterate over two elements. */
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assert(bpf_map_get_next_key(fd, NULL, &next_key) == 0 &&
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next_key == 0);
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assert(bpf_map_get_next_key(fd, &key, &next_key) == 0 &&
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next_key == 0);
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assert(bpf_map_get_next_key(fd, &next_key, &next_key) == 0 &&
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@ -319,6 +334,8 @@ static void test_arraymap_percpu(int task, void *data)
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assert(bpf_map_lookup_elem(fd, &key, values) == -1 && errno == ENOENT);
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/* Iterate over two elements. */
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assert(bpf_map_get_next_key(fd, NULL, &next_key) == 0 &&
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next_key == 0);
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assert(bpf_map_get_next_key(fd, &key, &next_key) == 0 &&
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next_key == 0);
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assert(bpf_map_get_next_key(fd, &next_key, &next_key) == 0 &&
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@ -400,6 +417,8 @@ static void test_map_large(void)
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errno == E2BIG);
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/* Iterate through all elements. */
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assert(bpf_map_get_next_key(fd, NULL, &key) == 0);
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key.c = -1;
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for (i = 0; i < MAP_SIZE; i++)
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assert(bpf_map_get_next_key(fd, &key, &key) == 0);
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assert(bpf_map_get_next_key(fd, &key, &key) == -1 && errno == ENOENT);
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@ -499,6 +518,7 @@ static void test_map_parallel(void)
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errno == EEXIST);
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/* Check that all elements were inserted. */
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assert(bpf_map_get_next_key(fd, NULL, &key) == 0);
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key = -1;
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for (i = 0; i < MAP_SIZE; i++)
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assert(bpf_map_get_next_key(fd, &key, &key) == 0);
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@ -518,6 +538,7 @@ static void test_map_parallel(void)
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/* Nothing should be left. */
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key = -1;
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assert(bpf_map_get_next_key(fd, NULL, &key) == -1 && errno == ENOENT);
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assert(bpf_map_get_next_key(fd, &key, &key) == -1 && errno == ENOENT);
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}
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