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bpf: lpm_trie: check left child of last leftmost node for NULL

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commit da2577fdd0932ea4eefe73903f1130ee366767d2 upstream.

If the leftmost parent node of the tree has does not have a child
on the left side, then trie_get_next_key (and bpftool map dump) will
not look at the child on the right.  This leads to the traversal
missing elements.

Lookup is not affected.

Update selftest to handle this case.

Reproducer:

 bpftool map create /sys/fs/bpf/lpm type lpm_trie key 6 \
     value 1 entries 256 name test_lpm flags 1
 bpftool map update pinned /sys/fs/bpf/lpm key  8 0 0 0  0   0 value 1
 bpftool map update pinned /sys/fs/bpf/lpm key 16 0 0 0  0 128 value 2
 bpftool map dump   pinned /sys/fs/bpf/lpm

Returns only 1 element. (2 expected)

Fixes: b471f2f1de ("bpf: implement MAP_GET_NEXT_KEY command for LPM_TRIE")
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jonathan Lemon 2019-06-08 12:54:19 -07:00 committed by Greg Kroah-Hartman
parent 5e558f9a6d
commit 4992d4af58
2 changed files with 45 additions and 5 deletions
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9
kernel/bpf/lpm_trie.c
View file

@ -676,9 +676,14 @@ static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
* have exact two children, so this function will never return NULL.
*/
for (node = search_root; node;) {
if (!(node->flags & LPM_TREE_NODE_FLAG_IM))
if (node->flags & LPM_TREE_NODE_FLAG_IM) {
node = rcu_dereference(node->child[0]);
} else {
next_node = node;
node = rcu_dereference(node->child[0]);
node = rcu_dereference(node->child[0]);
if (!node)
node = rcu_dereference(next_node->child[1]);
}
}
do_copy:
next_key->prefixlen = next_node->prefixlen;

41
tools/testing/selftests/bpf/test_lpm_map.c
View file

@ -573,13 +573,13 @@ static void test_lpm_get_next_key(void)
/* add one more element (total two) */
key_p->prefixlen = 24;
inet_pton(AF_INET, "192.168.0.0", key_p->data);
inet_pton(AF_INET, "192.168.128.0", key_p->data);
assert(bpf_map_update_elem(map_fd, key_p, &value, 0) == 0);
memset(key_p, 0, key_size);
assert(bpf_map_get_next_key(map_fd, NULL, key_p) == 0);
assert(key_p->prefixlen == 24 && key_p->data[0] == 192 &&
key_p->data[1] == 168 && key_p->data[2] == 0);
key_p->data[1] == 168 && key_p->data[2] == 128);
memset(next_key_p, 0, key_size);
assert(bpf_map_get_next_key(map_fd, key_p, next_key_p) == 0);
@ -592,7 +592,7 @@ static void test_lpm_get_next_key(void)
/* Add one more element (total three) */
key_p->prefixlen = 24;
inet_pton(AF_INET, "192.168.128.0", key_p->data);
inet_pton(AF_INET, "192.168.0.0", key_p->data);
assert(bpf_map_update_elem(map_fd, key_p, &value, 0) == 0);
memset(key_p, 0, key_size);
@ -643,6 +643,41 @@ static void test_lpm_get_next_key(void)
assert(bpf_map_get_next_key(map_fd, key_p, next_key_p) == -1 &&
errno == ENOENT);
/* Add one more element (total five) */
key_p->prefixlen = 28;
inet_pton(AF_INET, "192.168.1.128", key_p->data);
assert(bpf_map_update_elem(map_fd, key_p, &value, 0) == 0);
memset(key_p, 0, key_size);
assert(bpf_map_get_next_key(map_fd, NULL, key_p) == 0);
assert(key_p->prefixlen == 24 && key_p->data[0] == 192 &&
key_p->data[1] == 168 && key_p->data[2] == 0);
memset(next_key_p, 0, key_size);
assert(bpf_map_get_next_key(map_fd, key_p, next_key_p) == 0);
assert(next_key_p->prefixlen == 28 && next_key_p->data[0] == 192 &&
next_key_p->data[1] == 168 && next_key_p->data[2] == 1 &&
next_key_p->data[3] == 128);
memcpy(key_p, next_key_p, key_size);
assert(bpf_map_get_next_key(map_fd, key_p, next_key_p) == 0);
assert(next_key_p->prefixlen == 24 && next_key_p->data[0] == 192 &&
next_key_p->data[1] == 168 && next_key_p->data[2] == 1);
memcpy(key_p, next_key_p, key_size);
assert(bpf_map_get_next_key(map_fd, key_p, next_key_p) == 0);
assert(next_key_p->prefixlen == 24 && next_key_p->data[0] == 192 &&
next_key_p->data[1] == 168 && next_key_p->data[2] == 128);
memcpy(key_p, next_key_p, key_size);
assert(bpf_map_get_next_key(map_fd, key_p, next_key_p) == 0);
assert(next_key_p->prefixlen == 16 && next_key_p->data[0] == 192 &&
next_key_p->data[1] == 168);
memcpy(key_p, next_key_p, key_size);
assert(bpf_map_get_next_key(map_fd, key_p, next_key_p) == -1 &&
errno == ENOENT);
/* no exact matching key should return the first one in post order */
key_p->prefixlen = 22;
inet_pton(AF_INET, "192.168.1.0", key_p->data);