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