From da2577fdd0932ea4eefe73903f1130ee366767d2 Mon Sep 17 00:00:00 2001 From: Jonathan Lemon Date: Sat, 8 Jun 2019 12:54:19 -0700 Subject: [PATCH] bpf: lpm_trie: check left child of last leftmost node for NULL 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 Acked-by: Martin KaFai Lau Signed-off-by: Daniel Borkmann --- kernel/bpf/lpm_trie.c | 9 +++-- tools/testing/selftests/bpf/test_lpm_map.c | 41 ++++++++++++++++++++-- 2 files changed, 45 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index e61630c2e50b..864e2a496376 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -716,9 +716,14 @@ 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; diff --git a/tools/testing/selftests/bpf/test_lpm_map.c b/tools/testing/selftests/bpf/test_lpm_map.c index 02d7c871862a..006be3963977 100644 --- 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); @@ -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); -- 2.30.2