Commit 05526361 authored by Daniel Borkmann's avatar Daniel Borkmann
Browse files

Merge branch 'bpf-lpm-get-next-key' 



Yonghong Song says:

====================
This patch set implements MAP_GET_NEXT_KEY command for LPM_TRIE map.
This command is really useful for key enumeration, and for key deletion
if what keys in the trie are unknown.

Patch #1 implements the functionality in the kernel and patch #2
adds a test case in tools/testing/selftests/bpf.
====================

Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parents b7bcc0bb 8c417dc1

kernel/bpf/lpm_trie.c

+93 −2
Original line number Diff line number Diff line
@@ -591,9 +591,100 @@ unlock: 
	raw_spin_unlock(&trie->lock);

}



static int trie_get_next_key(struct bpf_map *map, void *key, void *next_key)

static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)

{

	return -ENOTSUPP;

	struct lpm_trie *trie = container_of(map, struct lpm_trie, map);

	struct bpf_lpm_trie_key *key = _key, *next_key = _next_key;

	struct lpm_trie_node *node, *next_node = NULL, *parent;

	struct lpm_trie_node **node_stack = NULL;

	struct lpm_trie_node __rcu **root;

	int err = 0, stack_ptr = -1;

	unsigned int next_bit;

	size_t matchlen;



	/* The get_next_key follows postorder. For the 4 node example in

	 * the top of this file, the trie_get_next_key() returns the following

	 * one after another:

	 *   192.168.0.0/24

	 *   192.168.1.0/24

	 *   192.168.128.0/24

	 *   192.168.0.0/16

	 *

	 * The idea is to return more specific keys before less specific ones.

	 */



	/* Empty trie */

	if (!rcu_dereference(trie->root))

		return -ENOENT;



	/* For invalid key, find the leftmost node in the trie */

	if (!key || key->prefixlen > trie->max_prefixlen) {

		root = &trie->root;

		goto find_leftmost;

	}



	node_stack = kmalloc(trie->max_prefixlen * sizeof(struct lpm_trie_node *),

			     GFP_USER | __GFP_NOWARN);

	if (!node_stack)

		return -ENOMEM;



	/* Try to find the exact node for the given key */

	for (node = rcu_dereference(trie->root); node;) {

		node_stack[++stack_ptr] = 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);

		node = rcu_dereference(node->child[next_bit]);

	}

	if (!node || node->prefixlen != key->prefixlen ||

	    (node->flags & LPM_TREE_NODE_FLAG_IM)) {

		root = &trie->root;

		goto find_leftmost;

	}



	/* The node with the exactly-matching key has been found,

	 * find the first node in postorder after the matched node.

	 */

	node = node_stack[stack_ptr];

	while (stack_ptr > 0) {

		parent = node_stack[stack_ptr - 1];

		if (rcu_dereference(parent->child[0]) == node &&

		    rcu_dereference(parent->child[1])) {

			root = &parent->child[1];

			goto find_leftmost;

		}

		if (!(parent->flags & LPM_TREE_NODE_FLAG_IM)) {

			next_node = parent;

			goto do_copy;

		}



		node = parent;

		stack_ptr--;

	}



	/* did not find anything */

	err = -ENOENT;

	goto free_stack;



find_leftmost:

	/* Find the leftmost non-intermediate node, all intermediate nodes

	 * have exact two children, so this function will never return NULL.

	 */

	for (node = rcu_dereference(*root); node;) {

		if (!(node->flags & LPM_TREE_NODE_FLAG_IM))

			next_node = node;

		node = rcu_dereference(node->child[0]);

	}

do_copy:

	next_key->prefixlen = next_node->prefixlen;

	memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key, data),

	       next_node->data, trie->data_size);

free_stack:

	kfree(node_stack);

	return err;

}



const struct bpf_map_ops trie_map_ops = {

tools/testing/selftests/bpf/test_lpm_map.c

+122 −0
Original line number Diff line number Diff line
@@ -521,6 +521,126 @@ static void test_lpm_delete(void) 
	close(map_fd);

}



static void test_lpm_get_next_key(void)

{

	struct bpf_lpm_trie_key *key_p, *next_key_p;

	size_t key_size;

	__u32 value = 0;

	int map_fd;



	key_size = sizeof(*key_p) + sizeof(__u32);

	key_p = alloca(key_size);

	next_key_p = 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);



	/* empty tree. get_next_key should return ENOENT */

	assert(bpf_map_get_next_key(map_fd, NULL, key_p) == -1 &&

	       errno == ENOENT);



	/* get and verify the first key, get the second one should fail. */

	key_p->prefixlen = 16;

	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);

	assert(bpf_map_get_next_key(map_fd, NULL, key_p) == 0);

	assert(key_p->prefixlen == 16 && key_p->data[0] == 192 &&

	       key_p->data[1] == 168);



	assert(bpf_map_get_next_key(map_fd, key_p, next_key_p) == -1 &&

	       errno == ENOENT);



	/* no exact matching key should get the first one in post order. */

	key_p->prefixlen = 8;

	assert(bpf_map_get_next_key(map_fd, NULL, key_p) == 0);

	assert(key_p->prefixlen == 16 && key_p->data[0] == 192 &&

	       key_p->data[1] == 168);



	/* add one more element (total two) */

	key_p->prefixlen = 24;

	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);

	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 == 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 three) */

	key_p->prefixlen = 24;

	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);



	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 == 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 four) */

	key_p->prefixlen = 24;

	inet_pton(AF_INET, "192.168.1.0", 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);



	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 == 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);

	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] == 0);



	close(map_fd);

}



int main(void)

{

	struct rlimit limit  = { RLIM_INFINITY, RLIM_INFINITY };
@@ -545,6 +665,8 @@ int main(void) 


	test_lpm_delete();



	test_lpm_get_next_key();



	printf("test_lpm: OK\n");

	return 0;

}

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