1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Longest prefix match list implementation
4 *
5 * Copyright (c) 2016,2017 Daniel Mack
6 * Copyright (c) 2016 David Herrmann
7 */
8
9#include <linux/bpf.h>
10#include <linux/btf.h>
11#include <linux/err.h>
12#include <linux/slab.h>
13#include <linux/spinlock.h>
14#include <linux/vmalloc.h>
15#include <net/ipv6.h>
16#include <uapi/linux/btf.h>
17#include <linux/btf_ids.h>
18
19/* Intermediate node */
20#define LPM_TREE_NODE_FLAG_IM BIT(0)
21
22struct lpm_trie_node;
23
24struct lpm_trie_node {
25 struct rcu_head rcu;
26 struct lpm_trie_node __rcu *child[2];
27 u32 prefixlen;
28 u32 flags;
29 u8 data[];
30};
31
32struct lpm_trie {
33 struct bpf_map map;
34 struct lpm_trie_node __rcu *root;
35 size_t n_entries;
36 size_t max_prefixlen;
37 size_t data_size;
38 spinlock_t lock;
39};
40
41/* This trie implements a longest prefix match algorithm that can be used to
42 * match IP addresses to a stored set of ranges.
43 *
44 * Data stored in @data of struct bpf_lpm_key and struct lpm_trie_node is
45 * interpreted as big endian, so data[0] stores the most significant byte.
46 *
47 * Match ranges are internally stored in instances of struct lpm_trie_node
48 * which each contain their prefix length as well as two pointers that may
49 * lead to more nodes containing more specific matches. Each node also stores
50 * a value that is defined by and returned to userspace via the update_elem
51 * and lookup functions.
52 *
53 * For instance, let's start with a trie that was created with a prefix length
54 * of 32, so it can be used for IPv4 addresses, and one single element that
55 * matches 192.168.0.0/16. The data array would hence contain
56 * [0xc0, 0xa8, 0x00, 0x00] in big-endian notation. This documentation will
57 * stick to IP-address notation for readability though.
58 *
59 * As the trie is empty initially, the new node (1) will be places as root
60 * node, denoted as (R) in the example below. As there are no other node, both
61 * child pointers are %NULL.
62 *
63 * +----------------+
64 * | (1) (R) |
65 * | 192.168.0.0/16 |
66 * | value: 1 |
67 * | [0] [1] |
68 * +----------------+
69 *
70 * Next, let's add a new node (2) matching 192.168.0.0/24. As there is already
71 * a node with the same data and a smaller prefix (ie, a less specific one),
72 * node (2) will become a child of (1). In child index depends on the next bit
73 * that is outside of what (1) matches, and that bit is 0, so (2) will be
74 * child[0] of (1):
75 *
76 * +----------------+
77 * | (1) (R) |
78 * | 192.168.0.0/16 |
79 * | value: 1 |
80 * | [0] [1] |
81 * +----------------+
82 * |
83 * +----------------+
84 * | (2) |
85 * | 192.168.0.0/24 |
86 * | value: 2 |
87 * | [0] [1] |
88 * +----------------+
89 *
90 * The child[1] slot of (1) could be filled with another node which has bit #17
91 * (the next bit after the ones that (1) matches on) set to 1. For instance,
92 * 192.168.128.0/24:
93 *
94 * +----------------+
95 * | (1) (R) |
96 * | 192.168.0.0/16 |
97 * | value: 1 |
98 * | [0] [1] |
99 * +----------------+
100 * | |
101 * +----------------+ +------------------+
102 * | (2) | | (3) |
103 * | 192.168.0.0/24 | | 192.168.128.0/24 |
104 * | value: 2 | | value: 3 |
105 * | [0] [1] | | [0] [1] |
106 * +----------------+ +------------------+
107 *
108 * Let's add another node (4) to the game for 192.168.1.0/24. In order to place
109 * it, node (1) is looked at first, and because (4) of the semantics laid out
110 * above (bit #17 is 0), it would normally be attached to (1) as child[0].
111 * However, that slot is already allocated, so a new node is needed in between.
112 * That node does not have a value attached to it and it will never be
113 * returned to users as result of a lookup. It is only there to differentiate
114 * the traversal further. It will get a prefix as wide as necessary to
115 * distinguish its two children:
116 *
117 * +----------------+
118 * | (1) (R) |
119 * | 192.168.0.0/16 |
120 * | value: 1 |
121 * | [0] [1] |
122 * +----------------+
123 * | |
124 * +----------------+ +------------------+
125 * | (4) (I) | | (3) |
126 * | 192.168.0.0/23 | | 192.168.128.0/24 |
127 * | value: --- | | value: 3 |
128 * | [0] [1] | | [0] [1] |
129 * +----------------+ +------------------+
130 * | |
131 * +----------------+ +----------------+
132 * | (2) | | (5) |
133 * | 192.168.0.0/24 | | 192.168.1.0/24 |
134 * | value: 2 | | value: 5 |
135 * | [0] [1] | | [0] [1] |
136 * +----------------+ +----------------+
137 *
138 * 192.168.1.1/32 would be a child of (5) etc.
139 *
140 * An intermediate node will be turned into a 'real' node on demand. In the
141 * example above, (4) would be re-used if 192.168.0.0/23 is added to the trie.
142 *
143 * A fully populated trie would have a height of 32 nodes, as the trie was
144 * created with a prefix length of 32.
145 *
146 * The lookup starts at the root node. If the current node matches and if there
147 * is a child that can be used to become more specific, the trie is traversed
148 * downwards. The last node in the traversal that is a non-intermediate one is
149 * returned.
150 */
151
152static inline int extract_bit(const u8 *data, size_t index)
153{
154 return !!(data[index / 8] & (1 << (7 - (index % 8))));
155}
156
157/**
158 * longest_prefix_match() - determine the longest prefix
159 * @trie: The trie to get internal sizes from
160 * @node: The node to operate on
161 * @key: The key to compare to @node
162 *
163 * Determine the longest prefix of @node that matches the bits in @key.
164 */
165static size_t longest_prefix_match(const struct lpm_trie *trie,
166 const struct lpm_trie_node *node,
167 const struct bpf_lpm_trie_key_u8 *key)
168{
169 u32 limit = min(node->prefixlen, key->prefixlen);
170 u32 prefixlen = 0, i = 0;
171
172 BUILD_BUG_ON(offsetof(struct lpm_trie_node, data) % sizeof(u32));
173 BUILD_BUG_ON(offsetof(struct bpf_lpm_trie_key_u8, data) % sizeof(u32));
174
175#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && defined(CONFIG_64BIT)
176
177 /* data_size >= 16 has very small probability.
178 * We do not use a loop for optimal code generation.
179 */
180 if (trie->data_size >= 8) {
181 u64 diff = be64_to_cpu(*(__be64 *)node->data ^
182 *(__be64 *)key->data);
183
184 prefixlen = 64 - fls64(x: diff);
185 if (prefixlen >= limit)
186 return limit;
187 if (diff)
188 return prefixlen;
189 i = 8;
190 }
191#endif
192
193 while (trie->data_size >= i + 4) {
194 u32 diff = be32_to_cpu(*(__be32 *)&node->data[i] ^
195 *(__be32 *)&key->data[i]);
196
197 prefixlen += 32 - fls(x: diff);
198 if (prefixlen >= limit)
199 return limit;
200 if (diff)
201 return prefixlen;
202 i += 4;
203 }
204
205 if (trie->data_size >= i + 2) {
206 u16 diff = be16_to_cpu(*(__be16 *)&node->data[i] ^
207 *(__be16 *)&key->data[i]);
208
209 prefixlen += 16 - fls(x: diff);
210 if (prefixlen >= limit)
211 return limit;
212 if (diff)
213 return prefixlen;
214 i += 2;
215 }
216
217 if (trie->data_size >= i + 1) {
218 prefixlen += 8 - fls(x: node->data[i] ^ key->data[i]);
219
220 if (prefixlen >= limit)
221 return limit;
222 }
223
224 return prefixlen;
225}
226
227/* Called from syscall or from eBPF program */
228static void *trie_lookup_elem(struct bpf_map *map, void *_key)
229{
230 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
231 struct lpm_trie_node *node, *found = NULL;
232 struct bpf_lpm_trie_key_u8 *key = _key;
233
234 if (key->prefixlen > trie->max_prefixlen)
235 return NULL;
236
237 /* Start walking the trie from the root node ... */
238
239 for (node = rcu_dereference_check(trie->root, rcu_read_lock_bh_held());
240 node;) {
241 unsigned int next_bit;
242 size_t matchlen;
243
244 /* Determine the longest prefix of @node that matches @key.
245 * If it's the maximum possible prefix for this trie, we have
246 * an exact match and can return it directly.
247 */
248 matchlen = longest_prefix_match(trie, node, key);
249 if (matchlen == trie->max_prefixlen) {
250 found = node;
251 break;
252 }
253
254 /* If the number of bits that match is smaller than the prefix
255 * length of @node, bail out and return the node we have seen
256 * last in the traversal (ie, the parent).
257 */
258 if (matchlen < node->prefixlen)
259 break;
260
261 /* Consider this node as return candidate unless it is an
262 * artificially added intermediate one.
263 */
264 if (!(node->flags & LPM_TREE_NODE_FLAG_IM))
265 found = node;
266
267 /* If the node match is fully satisfied, let's see if we can
268 * become more specific. Determine the next bit in the key and
269 * traverse down.
270 */
271 next_bit = extract_bit(data: key->data, index: node->prefixlen);
272 node = rcu_dereference_check(node->child[next_bit],
273 rcu_read_lock_bh_held());
274 }
275
276 if (!found)
277 return NULL;
278
279 return found->data + trie->data_size;
280}
281
282static struct lpm_trie_node *lpm_trie_node_alloc(const struct lpm_trie *trie,
283 const void *value)
284{
285 struct lpm_trie_node *node;
286 size_t size = sizeof(struct lpm_trie_node) + trie->data_size;
287
288 if (value)
289 size += trie->map.value_size;
290
291 node = bpf_map_kmalloc_node(map: &trie->map, size, GFP_NOWAIT | __GFP_NOWARN,
292 node: trie->map.numa_node);
293 if (!node)
294 return NULL;
295
296 node->flags = 0;
297
298 if (value)
299 memcpy(node->data + trie->data_size, value,
300 trie->map.value_size);
301
302 return node;
303}
304
305/* Called from syscall or from eBPF program */
306static long trie_update_elem(struct bpf_map *map,
307 void *_key, void *value, u64 flags)
308{
309 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
310 struct lpm_trie_node *node, *im_node = NULL, *new_node = NULL;
311 struct lpm_trie_node __rcu **slot;
312 struct bpf_lpm_trie_key_u8 *key = _key;
313 unsigned long irq_flags;
314 unsigned int next_bit;
315 size_t matchlen = 0;
316 int ret = 0;
317
318 if (unlikely(flags > BPF_EXIST))
319 return -EINVAL;
320
321 if (key->prefixlen > trie->max_prefixlen)
322 return -EINVAL;
323
324 spin_lock_irqsave(&trie->lock, irq_flags);
325
326 /* Allocate and fill a new node */
327
328 if (trie->n_entries == trie->map.max_entries) {
329 ret = -ENOSPC;
330 goto out;
331 }
332
333 new_node = lpm_trie_node_alloc(trie, value);
334 if (!new_node) {
335 ret = -ENOMEM;
336 goto out;
337 }
338
339 trie->n_entries++;
340
341 new_node->prefixlen = key->prefixlen;
342 RCU_INIT_POINTER(new_node->child[0], NULL);
343 RCU_INIT_POINTER(new_node->child[1], NULL);
344 memcpy(new_node->data, key->data, trie->data_size);
345
346 /* Now find a slot to attach the new node. To do that, walk the tree
347 * from the root and match as many bits as possible for each node until
348 * we either find an empty slot or a slot that needs to be replaced by
349 * an intermediate node.
350 */
351 slot = &trie->root;
352
353 while ((node = rcu_dereference_protected(*slot,
354 lockdep_is_held(&trie->lock)))) {
355 matchlen = longest_prefix_match(trie, node, key);
356
357 if (node->prefixlen != matchlen ||
358 node->prefixlen == key->prefixlen ||
359 node->prefixlen == trie->max_prefixlen)
360 break;
361
362 next_bit = extract_bit(data: key->data, index: node->prefixlen);
363 slot = &node->child[next_bit];
364 }
365
366 /* If the slot is empty (a free child pointer or an empty root),
367 * simply assign the @new_node to that slot and be done.
368 */
369 if (!node) {
370 rcu_assign_pointer(*slot, new_node);
371 goto out;
372 }
373
374 /* If the slot we picked already exists, replace it with @new_node
375 * which already has the correct data array set.
376 */
377 if (node->prefixlen == matchlen) {
378 new_node->child[0] = node->child[0];
379 new_node->child[1] = node->child[1];
380
381 if (!(node->flags & LPM_TREE_NODE_FLAG_IM))
382 trie->n_entries--;
383
384 rcu_assign_pointer(*slot, new_node);
385 kfree_rcu(node, rcu);
386
387 goto out;
388 }
389
390 /* If the new node matches the prefix completely, it must be inserted
391 * as an ancestor. Simply insert it between @node and *@slot.
392 */
393 if (matchlen == key->prefixlen) {
394 next_bit = extract_bit(data: node->data, index: matchlen);
395 rcu_assign_pointer(new_node->child[next_bit], node);
396 rcu_assign_pointer(*slot, new_node);
397 goto out;
398 }
399
400 im_node = lpm_trie_node_alloc(trie, NULL);
401 if (!im_node) {
402 ret = -ENOMEM;
403 goto out;
404 }
405
406 im_node->prefixlen = matchlen;
407 im_node->flags |= LPM_TREE_NODE_FLAG_IM;
408 memcpy(im_node->data, node->data, trie->data_size);
409
410 /* Now determine which child to install in which slot */
411 if (extract_bit(data: key->data, index: matchlen)) {
412 rcu_assign_pointer(im_node->child[0], node);
413 rcu_assign_pointer(im_node->child[1], new_node);
414 } else {
415 rcu_assign_pointer(im_node->child[0], new_node);
416 rcu_assign_pointer(im_node->child[1], node);
417 }
418
419 /* Finally, assign the intermediate node to the determined slot */
420 rcu_assign_pointer(*slot, im_node);
421
422out:
423 if (ret) {
424 if (new_node)
425 trie->n_entries--;
426
427 kfree(objp: new_node);
428 kfree(objp: im_node);
429 }
430
431 spin_unlock_irqrestore(lock: &trie->lock, flags: irq_flags);
432
433 return ret;
434}
435
436/* Called from syscall or from eBPF program */
437static long trie_delete_elem(struct bpf_map *map, void *_key)
438{
439 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
440 struct bpf_lpm_trie_key_u8 *key = _key;
441 struct lpm_trie_node __rcu **trim, **trim2;
442 struct lpm_trie_node *node, *parent;
443 unsigned long irq_flags;
444 unsigned int next_bit;
445 size_t matchlen = 0;
446 int ret = 0;
447
448 if (key->prefixlen > trie->max_prefixlen)
449 return -EINVAL;
450
451 spin_lock_irqsave(&trie->lock, irq_flags);
452
453 /* Walk the tree looking for an exact key/length match and keeping
454 * track of the path we traverse. We will need to know the node
455 * we wish to delete, and the slot that points to the node we want
456 * to delete. We may also need to know the nodes parent and the
457 * slot that contains it.
458 */
459 trim = &trie->root;
460 trim2 = trim;
461 parent = NULL;
462 while ((node = rcu_dereference_protected(
463 *trim, lockdep_is_held(&trie->lock)))) {
464 matchlen = longest_prefix_match(trie, node, key);
465
466 if (node->prefixlen != matchlen ||
467 node->prefixlen == key->prefixlen)
468 break;
469
470 parent = node;
471 trim2 = trim;
472 next_bit = extract_bit(data: key->data, index: node->prefixlen);
473 trim = &node->child[next_bit];
474 }
475
476 if (!node || node->prefixlen != key->prefixlen ||
477 node->prefixlen != matchlen ||
478 (node->flags & LPM_TREE_NODE_FLAG_IM)) {
479 ret = -ENOENT;
480 goto out;
481 }
482
483 trie->n_entries--;
484
485 /* If the node we are removing has two children, simply mark it
486 * as intermediate and we are done.
487 */
488 if (rcu_access_pointer(node->child[0]) &&
489 rcu_access_pointer(node->child[1])) {
490 node->flags |= LPM_TREE_NODE_FLAG_IM;
491 goto out;
492 }
493
494 /* If the parent of the node we are about to delete is an intermediate
495 * node, and the deleted node doesn't have any children, we can delete
496 * the intermediate parent as well and promote its other child
497 * up the tree. Doing this maintains the invariant that all
498 * intermediate nodes have exactly 2 children and that there are no
499 * unnecessary intermediate nodes in the tree.
500 */
501 if (parent && (parent->flags & LPM_TREE_NODE_FLAG_IM) &&
502 !node->child[0] && !node->child[1]) {
503 if (node == rcu_access_pointer(parent->child[0]))
504 rcu_assign_pointer(
505 *trim2, rcu_access_pointer(parent->child[1]));
506 else
507 rcu_assign_pointer(
508 *trim2, rcu_access_pointer(parent->child[0]));
509 kfree_rcu(parent, rcu);
510 kfree_rcu(node, rcu);
511 goto out;
512 }
513
514 /* The node we are removing has either zero or one child. If there
515 * is a child, move it into the removed node's slot then delete
516 * the node. Otherwise just clear the slot and delete the node.
517 */
518 if (node->child[0])
519 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[0]));
520 else if (node->child[1])
521 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[1]));
522 else
523 RCU_INIT_POINTER(*trim, NULL);
524 kfree_rcu(node, rcu);
525
526out:
527 spin_unlock_irqrestore(lock: &trie->lock, flags: irq_flags);
528
529 return ret;
530}
531
532#define LPM_DATA_SIZE_MAX 256
533#define LPM_DATA_SIZE_MIN 1
534
535#define LPM_VAL_SIZE_MAX (KMALLOC_MAX_SIZE - LPM_DATA_SIZE_MAX - \
536 sizeof(struct lpm_trie_node))
537#define LPM_VAL_SIZE_MIN 1
538
539#define LPM_KEY_SIZE(X) (sizeof(struct bpf_lpm_trie_key_u8) + (X))
540#define LPM_KEY_SIZE_MAX LPM_KEY_SIZE(LPM_DATA_SIZE_MAX)
541#define LPM_KEY_SIZE_MIN LPM_KEY_SIZE(LPM_DATA_SIZE_MIN)
542
543#define LPM_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_NUMA_NODE | \
544 BPF_F_ACCESS_MASK)
545
546static struct bpf_map *trie_alloc(union bpf_attr *attr)
547{
548 struct lpm_trie *trie;
549
550 /* check sanity of attributes */
551 if (attr->max_entries == 0 ||
552 !(attr->map_flags & BPF_F_NO_PREALLOC) ||
553 attr->map_flags & ~LPM_CREATE_FLAG_MASK ||
554 !bpf_map_flags_access_ok(access_flags: attr->map_flags) ||
555 attr->key_size < LPM_KEY_SIZE_MIN ||
556 attr->key_size > LPM_KEY_SIZE_MAX ||
557 attr->value_size < LPM_VAL_SIZE_MIN ||
558 attr->value_size > LPM_VAL_SIZE_MAX)
559 return ERR_PTR(error: -EINVAL);
560
561 trie = bpf_map_area_alloc(size: sizeof(*trie), NUMA_NO_NODE);
562 if (!trie)
563 return ERR_PTR(error: -ENOMEM);
564
565 /* copy mandatory map attributes */
566 bpf_map_init_from_attr(map: &trie->map, attr);
567 trie->data_size = attr->key_size -
568 offsetof(struct bpf_lpm_trie_key_u8, data);
569 trie->max_prefixlen = trie->data_size * 8;
570
571 spin_lock_init(&trie->lock);
572
573 return &trie->map;
574}
575
576static void trie_free(struct bpf_map *map)
577{
578 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
579 struct lpm_trie_node __rcu **slot;
580 struct lpm_trie_node *node;
581
582 /* Always start at the root and walk down to a node that has no
583 * children. Then free that node, nullify its reference in the parent
584 * and start over.
585 */
586
587 for (;;) {
588 slot = &trie->root;
589
590 for (;;) {
591 node = rcu_dereference_protected(*slot, 1);
592 if (!node)
593 goto out;
594
595 if (rcu_access_pointer(node->child[0])) {
596 slot = &node->child[0];
597 continue;
598 }
599
600 if (rcu_access_pointer(node->child[1])) {
601 slot = &node->child[1];
602 continue;
603 }
604
605 kfree(objp: node);
606 RCU_INIT_POINTER(*slot, NULL);
607 break;
608 }
609 }
610
611out:
612 bpf_map_area_free(base: trie);
613}
614
615static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
616{
617 struct lpm_trie_node *node, *next_node = NULL, *parent, *search_root;
618 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
619 struct bpf_lpm_trie_key_u8 *key = _key, *next_key = _next_key;
620 struct lpm_trie_node **node_stack = NULL;
621 int err = 0, stack_ptr = -1;
622 unsigned int next_bit;
623 size_t matchlen;
624
625 /* The get_next_key follows postorder. For the 4 node example in
626 * the top of this file, the trie_get_next_key() returns the following
627 * one after another:
628 * 192.168.0.0/24
629 * 192.168.1.0/24
630 * 192.168.128.0/24
631 * 192.168.0.0/16
632 *
633 * The idea is to return more specific keys before less specific ones.
634 */
635
636 /* Empty trie */
637 search_root = rcu_dereference(trie->root);
638 if (!search_root)
639 return -ENOENT;
640
641 /* For invalid key, find the leftmost node in the trie */
642 if (!key || key->prefixlen > trie->max_prefixlen)
643 goto find_leftmost;
644
645 node_stack = kmalloc_array(n: trie->max_prefixlen,
646 size: sizeof(struct lpm_trie_node *),
647 GFP_ATOMIC | __GFP_NOWARN);
648 if (!node_stack)
649 return -ENOMEM;
650
651 /* Try to find the exact node for the given key */
652 for (node = search_root; node;) {
653 node_stack[++stack_ptr] = node;
654 matchlen = longest_prefix_match(trie, node, key);
655 if (node->prefixlen != matchlen ||
656 node->prefixlen == key->prefixlen)
657 break;
658
659 next_bit = extract_bit(data: key->data, index: node->prefixlen);
660 node = rcu_dereference(node->child[next_bit]);
661 }
662 if (!node || node->prefixlen != key->prefixlen ||
663 (node->flags & LPM_TREE_NODE_FLAG_IM))
664 goto find_leftmost;
665
666 /* The node with the exactly-matching key has been found,
667 * find the first node in postorder after the matched node.
668 */
669 node = node_stack[stack_ptr];
670 while (stack_ptr > 0) {
671 parent = node_stack[stack_ptr - 1];
672 if (rcu_dereference(parent->child[0]) == node) {
673 search_root = rcu_dereference(parent->child[1]);
674 if (search_root)
675 goto find_leftmost;
676 }
677 if (!(parent->flags & LPM_TREE_NODE_FLAG_IM)) {
678 next_node = parent;
679 goto do_copy;
680 }
681
682 node = parent;
683 stack_ptr--;
684 }
685
686 /* did not find anything */
687 err = -ENOENT;
688 goto free_stack;
689
690find_leftmost:
691 /* Find the leftmost non-intermediate node, all intermediate nodes
692 * have exact two children, so this function will never return NULL.
693 */
694 for (node = search_root; node;) {
695 if (node->flags & LPM_TREE_NODE_FLAG_IM) {
696 node = rcu_dereference(node->child[0]);
697 } else {
698 next_node = node;
699 node = rcu_dereference(node->child[0]);
700 if (!node)
701 node = rcu_dereference(next_node->child[1]);
702 }
703 }
704do_copy:
705 next_key->prefixlen = next_node->prefixlen;
706 memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key_u8, data),
707 next_node->data, trie->data_size);
708free_stack:
709 kfree(objp: node_stack);
710 return err;
711}
712
713static int trie_check_btf(const struct bpf_map *map,
714 const struct btf *btf,
715 const struct btf_type *key_type,
716 const struct btf_type *value_type)
717{
718 /* Keys must have struct bpf_lpm_trie_key_u8 embedded. */
719 return BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ?
720 -EINVAL : 0;
721}
722
723static u64 trie_mem_usage(const struct bpf_map *map)
724{
725 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
726 u64 elem_size;
727
728 elem_size = sizeof(struct lpm_trie_node) + trie->data_size +
729 trie->map.value_size;
730 return elem_size * READ_ONCE(trie->n_entries);
731}
732
733BTF_ID_LIST_SINGLE(trie_map_btf_ids, struct, lpm_trie)
734const struct bpf_map_ops trie_map_ops = {
735 .map_meta_equal = bpf_map_meta_equal,
736 .map_alloc = trie_alloc,
737 .map_free = trie_free,
738 .map_get_next_key = trie_get_next_key,
739 .map_lookup_elem = trie_lookup_elem,
740 .map_update_elem = trie_update_elem,
741 .map_delete_elem = trie_delete_elem,
742 .map_lookup_batch = generic_map_lookup_batch,
743 .map_update_batch = generic_map_update_batch,
744 .map_delete_batch = generic_map_delete_batch,
745 .map_check_btf = trie_check_btf,
746 .map_mem_usage = trie_mem_usage,
747 .map_btf_id = &trie_map_btf_ids[0],
748};
749

source code of linux/kernel/bpf/lpm_trie.c