From: Jonathan Lemon jonathan.lemon@gmail.com
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: b471f2f1de8b ("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
--- kernel/bpf/lpm_trie.c | 9 ++++-- tools/testing/selftests/bpf/test_lpm_map.c | 41 ++++++++++++++++++++++++++--- 2 files changed, 45 insertions(+), 5 deletions(-)
--- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -676,9 +676,14 @@ find_leftmost: * 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; --- a/tools/testing/selftests/bpf/test_lpm_map.c +++ b/tools/testing/selftests/bpf/test_lpm_map.c @@ -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); @@ -628,6 +628,41 @@ static void test_lpm_get_next_key(void) 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); + + /* 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);