From e454cf5958538666635488030046b6a84a22d447 Mon Sep 17 00:00:00 2001 From: Craig Gallek Date: Mon, 18 Sep 2017 15:30:55 -0400 Subject: bpf: Implement map_delete_elem for BPF_MAP_TYPE_LPM_TRIE This is a simple non-recursive delete operation. It prunes paths of empty nodes in the tree, but it does not try to further compress the tree as nodes are removed. Signed-off-by: Craig Gallek Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- kernel/bpf/lpm_trie.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 77 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index 1b767844a76f..9d58a576b2ae 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -389,10 +389,84 @@ out: return ret; } -static int trie_delete_elem(struct bpf_map *map, void *key) +/* Called from syscall or from eBPF program */ +static int trie_delete_elem(struct bpf_map *map, void *_key) { - /* TODO */ - return -ENOSYS; + struct lpm_trie *trie = container_of(map, struct lpm_trie, map); + struct bpf_lpm_trie_key *key = _key; + struct lpm_trie_node __rcu **trim; + struct lpm_trie_node *node; + unsigned long irq_flags; + unsigned int next_bit; + size_t matchlen = 0; + int ret = 0; + + if (key->prefixlen > trie->max_prefixlen) + return -EINVAL; + + raw_spin_lock_irqsave(&trie->lock, irq_flags); + + /* Walk the tree looking for an exact key/length match and keeping + * track of where we could begin trimming the tree. The trim-point + * is the sub-tree along the walk consisting of only single-child + * intermediate nodes and ending at a leaf node that we want to + * remove. + */ + trim = &trie->root; + node = rcu_dereference_protected( + trie->root, lockdep_is_held(&trie->lock)); + while (node) { + matchlen = longest_prefix_match(trie, node, key); + + if (node->prefixlen != matchlen || + node->prefixlen == key->prefixlen) + break; + + next_bit = extract_bit(key->data, node->prefixlen); + /* If we hit a node that has more than one child or is a valid + * prefix itself, do not remove it. Reset the root of the trim + * path to its descendant on our path. + */ + if (!(node->flags & LPM_TREE_NODE_FLAG_IM) || + (node->child[0] && node->child[1])) + trim = &node->child[next_bit]; + node = rcu_dereference_protected( + node->child[next_bit], lockdep_is_held(&trie->lock)); + } + + if (!node || node->prefixlen != key->prefixlen || + (node->flags & LPM_TREE_NODE_FLAG_IM)) { + ret = -ENOENT; + goto out; + } + + trie->n_entries--; + + /* If the node we are removing is not a leaf node, simply mark it + * as intermediate and we are done. + */ + if (rcu_access_pointer(node->child[0]) || + rcu_access_pointer(node->child[1])) { + node->flags |= LPM_TREE_NODE_FLAG_IM; + goto out; + } + + /* trim should now point to the slot holding the start of a path from + * zero or more intermediate nodes to our leaf node for deletion. + */ + while ((node = rcu_dereference_protected( + *trim, lockdep_is_held(&trie->lock)))) { + RCU_INIT_POINTER(*trim, NULL); + trim = rcu_access_pointer(node->child[0]) ? + &node->child[0] : + &node->child[1]; + kfree_rcu(node, rcu); + } + +out: + raw_spin_unlock_irqrestore(&trie->lock, irq_flags); + + return ret; } #define LPM_DATA_SIZE_MAX 256 -- cgit v1.2.3 From bae30468dfc1522464f16051addd7bc7da6da75a Mon Sep 17 00:00:00 2001 From: Craig Gallek Date: Mon, 18 Sep 2017 15:30:56 -0400 Subject: bpf: Add uniqueness invariant to trivial lpm test implementation The 'trivial' lpm implementation in this test allows equivalent nodes to be added (that is, nodes consisting of the same prefix and prefix length). For lookup operations, this is fine because insertion happens at the head of the (singly linked) list and the first, best match is returned. In order to support deletion, the tlpm data structue must first enforce uniqueness. This change modifies the insertion algorithm to search for equivalent nodes and remove them. Note: the BPF_MAP_TYPE_LPM_TRIE already has a uniqueness invariant that is implemented as node replacement. Signed-off-by: Craig Gallek Acked-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- tools/testing/selftests/bpf/test_lpm_map.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/test_lpm_map.c b/tools/testing/selftests/bpf/test_lpm_map.c index e97565243d59..a5ed7c4f1819 100644 --- a/tools/testing/selftests/bpf/test_lpm_map.c +++ b/tools/testing/selftests/bpf/test_lpm_map.c @@ -31,6 +31,10 @@ struct tlpm_node { uint8_t key[]; }; +static struct tlpm_node *tlpm_match(struct tlpm_node *list, + const uint8_t *key, + size_t n_bits); + static struct tlpm_node *tlpm_add(struct tlpm_node *list, const uint8_t *key, size_t n_bits) @@ -38,9 +42,17 @@ static struct tlpm_node *tlpm_add(struct tlpm_node *list, struct tlpm_node *node; size_t n; + n = (n_bits + 7) / 8; + + /* 'overwrite' an equivalent entry if one already exists */ + node = tlpm_match(list, key, n_bits); + if (node && node->n_bits == n_bits) { + memcpy(node->key, key, n); + return list; + } + /* add new entry with @key/@n_bits to @list and return new head */ - n = (n_bits + 7) / 8; node = malloc(sizeof(*node) + n); assert(node); -- cgit v1.2.3 From e8d1749910b56a7248cb9a5392274348d10108bb Mon Sep 17 00:00:00 2001 From: Craig Gallek Date: Mon, 18 Sep 2017 15:30:57 -0400 Subject: bpf: Test deletion in BPF_MAP_TYPE_LPM_TRIE Extend the 'random' operation tests to include a delete operation (delete half of the nodes from both lpm implementions and ensure that lookups are still equivalent). Also, add a simple IPv4 test which verifies lookup behavior as nodes are deleted from the tree. Signed-off-by: Craig Gallek Acked-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- tools/testing/selftests/bpf/test_lpm_map.c | 187 ++++++++++++++++++++++++++++- 1 file changed, 183 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/bpf/test_lpm_map.c b/tools/testing/selftests/bpf/test_lpm_map.c index a5ed7c4f1819..6fedb9fec36b 100644 --- a/tools/testing/selftests/bpf/test_lpm_map.c +++ b/tools/testing/selftests/bpf/test_lpm_map.c @@ -104,6 +104,34 @@ static struct tlpm_node *tlpm_match(struct tlpm_node *list, return best; } +static struct tlpm_node *tlpm_delete(struct tlpm_node *list, + const uint8_t *key, + size_t n_bits) +{ + struct tlpm_node *best = tlpm_match(list, key, n_bits); + struct tlpm_node *node; + + if (!best || best->n_bits != n_bits) + return list; + + if (best == list) { + node = best->next; + free(best); + return node; + } + + for (node = list; node; node = node->next) { + if (node->next == best) { + node->next = best->next; + free(best); + return list; + } + } + /* should never get here */ + assert(0); + return list; +} + static void test_lpm_basic(void) { struct tlpm_node *list = NULL, *t1, *t2; @@ -126,6 +154,13 @@ static void test_lpm_basic(void) assert(t1 == tlpm_match(list, (uint8_t[]){ 0xff, 0xff }, 15)); assert(!tlpm_match(list, (uint8_t[]){ 0x7f, 0xff }, 16)); + list = tlpm_delete(list, (uint8_t[]){ 0xff, 0xff }, 16); + assert(t1 == tlpm_match(list, (uint8_t[]){ 0xff }, 8)); + assert(t1 == tlpm_match(list, (uint8_t[]){ 0xff, 0xff }, 16)); + + list = tlpm_delete(list, (uint8_t[]){ 0xff }, 8); + assert(!tlpm_match(list, (uint8_t[]){ 0xff }, 8)); + tlpm_clear(list); } @@ -170,7 +205,7 @@ static void test_lpm_order(void) static void test_lpm_map(int keysize) { - size_t i, j, n_matches, n_nodes, n_lookups; + size_t i, j, n_matches, n_matches_after_delete, n_nodes, n_lookups; struct tlpm_node *t, *list = NULL; struct bpf_lpm_trie_key *key; uint8_t *data, *value; @@ -182,6 +217,7 @@ static void test_lpm_map(int keysize) */ n_matches = 0; + n_matches_after_delete = 0; n_nodes = 1 << 8; n_lookups = 1 << 16; @@ -235,15 +271,54 @@ static void test_lpm_map(int keysize) } } + /* Remove the first half of the elements in the tlpm and the + * corresponding nodes from the bpf-lpm. Then run the same + * large number of random lookups in both and make sure they match. + * Note: we need to count the number of nodes actually inserted + * since there may have been duplicates. + */ + for (i = 0, t = list; t; i++, t = t->next) + ; + for (j = 0; j < i / 2; ++j) { + key->prefixlen = list->n_bits; + memcpy(key->data, list->key, keysize); + r = bpf_map_delete_elem(map, key); + assert(!r); + list = tlpm_delete(list, list->key, list->n_bits); + assert(list); + } + for (i = 0; i < n_lookups; ++i) { + for (j = 0; j < keysize; ++j) + data[j] = rand() & 0xff; + + t = tlpm_match(list, data, 8 * keysize); + + key->prefixlen = 8 * keysize; + memcpy(key->data, data, keysize); + r = bpf_map_lookup_elem(map, key, value); + assert(!r || errno == ENOENT); + assert(!t == !!r); + + if (t) { + ++n_matches_after_delete; + assert(t->n_bits == value[keysize]); + for (j = 0; j < t->n_bits; ++j) + assert((t->key[j / 8] & (1 << (7 - j % 8))) == + (value[j / 8] & (1 << (7 - j % 8)))); + } + } + close(map); tlpm_clear(list); /* With 255 random nodes in the map, we are pretty likely to match * something on every lookup. For statistics, use this: * - * printf(" nodes: %zu\n" - * "lookups: %zu\n" - * "matches: %zu\n", n_nodes, n_lookups, n_matches); + * printf(" nodes: %zu\n" + * " lookups: %zu\n" + * " matches: %zu\n" + * "matches(delete): %zu\n", + * n_nodes, n_lookups, n_matches, n_matches_after_delete); */ } @@ -343,6 +418,108 @@ static void test_lpm_ipaddr(void) close(map_fd_ipv6); } +static void test_lpm_delete(void) +{ + struct bpf_lpm_trie_key *key; + size_t key_size; + int map_fd; + __u64 value; + + key_size = sizeof(*key) + sizeof(__u32); + key = alloca(key_size); + + map_fd = bpf_create_map(BPF_MAP_TYPE_LPM_TRIE, + key_size, sizeof(value), + 100, BPF_F_NO_PREALLOC); + assert(map_fd >= 0); + + /* Add nodes: + * 192.168.0.0/16 (1) + * 192.168.0.0/24 (2) + * 192.168.128.0/24 (3) + * 192.168.1.0/24 (4) + * + * (1) + * / \ + * (IM) (3) + * / \ + * (2) (4) + */ + value = 1; + key->prefixlen = 16; + inet_pton(AF_INET, "192.168.0.0", key->data); + assert(bpf_map_update_elem(map_fd, key, &value, 0) == 0); + + value = 2; + key->prefixlen = 24; + inet_pton(AF_INET, "192.168.0.0", key->data); + assert(bpf_map_update_elem(map_fd, key, &value, 0) == 0); + + value = 3; + key->prefixlen = 24; + inet_pton(AF_INET, "192.168.128.0", key->data); + assert(bpf_map_update_elem(map_fd, key, &value, 0) == 0); + + value = 4; + key->prefixlen = 24; + inet_pton(AF_INET, "192.168.1.0", key->data); + assert(bpf_map_update_elem(map_fd, key, &value, 0) == 0); + + /* remove non-existent node */ + key->prefixlen = 32; + inet_pton(AF_INET, "10.0.0.1", key->data); + assert(bpf_map_lookup_elem(map_fd, key, &value) == -1 && + errno == ENOENT); + + /* assert initial lookup */ + key->prefixlen = 32; + inet_pton(AF_INET, "192.168.0.1", key->data); + assert(bpf_map_lookup_elem(map_fd, key, &value) == 0); + assert(value == 2); + + /* remove leaf node */ + key->prefixlen = 24; + inet_pton(AF_INET, "192.168.0.0", key->data); + assert(bpf_map_delete_elem(map_fd, key) == 0); + + key->prefixlen = 32; + inet_pton(AF_INET, "192.168.0.1", key->data); + assert(bpf_map_lookup_elem(map_fd, key, &value) == 0); + assert(value == 1); + + /* remove leaf (and intermediary) node */ + key->prefixlen = 24; + inet_pton(AF_INET, "192.168.1.0", key->data); + assert(bpf_map_delete_elem(map_fd, key) == 0); + + key->prefixlen = 32; + inet_pton(AF_INET, "192.168.1.1", key->data); + assert(bpf_map_lookup_elem(map_fd, key, &value) == 0); + assert(value == 1); + + /* remove root node */ + key->prefixlen = 16; + inet_pton(AF_INET, "192.168.0.0", key->data); + assert(bpf_map_delete_elem(map_fd, key) == 0); + + key->prefixlen = 32; + inet_pton(AF_INET, "192.168.128.1", key->data); + assert(bpf_map_lookup_elem(map_fd, key, &value) == 0); + assert(value == 3); + + /* remove last node */ + key->prefixlen = 24; + inet_pton(AF_INET, "192.168.128.0", key->data); + assert(bpf_map_delete_elem(map_fd, key) == 0); + + key->prefixlen = 32; + inet_pton(AF_INET, "192.168.128.1", key->data); + assert(bpf_map_lookup_elem(map_fd, key, &value) == -1 && + errno == ENOENT); + + close(map_fd); +} + int main(void) { struct rlimit limit = { RLIM_INFINITY, RLIM_INFINITY }; @@ -365,6 +542,8 @@ int main(void) test_lpm_ipaddr(); + test_lpm_delete(); + printf("test_lpm: OK\n"); return 0; } -- cgit v1.2.3