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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 *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, 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(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(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(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(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 *key = _key;
233
234 /* Start walking the trie from the root node ... */
235
236 for (node = rcu_dereference_check(trie->root, rcu_read_lock_bh_held());
237 node;) {
238 unsigned int next_bit;
239 size_t matchlen;
240
241 /* Determine the longest prefix of @node that matches @key.
242 * If it's the maximum possible prefix for this trie, we have
243 * an exact match and can return it directly.
244 */
245 matchlen = longest_prefix_match(trie, node, key);
246 if (matchlen == trie->max_prefixlen) {
247 found = node;
248 break;
249 }
250
251 /* If the number of bits that match is smaller than the prefix
252 * length of @node, bail out and return the node we have seen
253 * last in the traversal (ie, the parent).
254 */
255 if (matchlen < node->prefixlen)
256 break;
257
258 /* Consider this node as return candidate unless it is an
259 * artificially added intermediate one.
260 */
261 if (!(node->flags & LPM_TREE_NODE_FLAG_IM))
262 found = node;
263
264 /* If the node match is fully satisfied, let's see if we can
265 * become more specific. Determine the next bit in the key and
266 * traverse down.
267 */
268 next_bit = extract_bit(key->data, node->prefixlen);
269 node = rcu_dereference_check(node->child[next_bit],
270 rcu_read_lock_bh_held());
271 }
272
273 if (!found)
274 return NULL;
275
276 return found->data + trie->data_size;
277}
278
279static struct lpm_trie_node *lpm_trie_node_alloc(const struct lpm_trie *trie,
280 const void *value)
281{
282 struct lpm_trie_node *node;
283 size_t size = sizeof(struct lpm_trie_node) + trie->data_size;
284
285 if (value)
286 size += trie->map.value_size;
287
288 node = bpf_map_kmalloc_node(&trie->map, size, GFP_NOWAIT | __GFP_NOWARN,
289 trie->map.numa_node);
290 if (!node)
291 return NULL;
292
293 node->flags = 0;
294
295 if (value)
296 memcpy(node->data + trie->data_size, value,
297 trie->map.value_size);
298
299 return node;
300}
301
302/* Called from syscall or from eBPF program */
303static int trie_update_elem(struct bpf_map *map,
304 void *_key, void *value, u64 flags)
305{
306 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
307 struct lpm_trie_node *node, *im_node = NULL, *new_node = NULL;
308 struct lpm_trie_node __rcu **slot;
309 struct bpf_lpm_trie_key *key = _key;
310 unsigned long irq_flags;
311 unsigned int next_bit;
312 size_t matchlen = 0;
313 int ret = 0;
314
315 if (unlikely(flags > BPF_EXIST))
316 return -EINVAL;
317
318 if (key->prefixlen > trie->max_prefixlen)
319 return -EINVAL;
320
321 spin_lock_irqsave(&trie->lock, irq_flags);
322
323 /* Allocate and fill a new node */
324
325 if (trie->n_entries == trie->map.max_entries) {
326 ret = -ENOSPC;
327 goto out;
328 }
329
330 new_node = lpm_trie_node_alloc(trie, value);
331 if (!new_node) {
332 ret = -ENOMEM;
333 goto out;
334 }
335
336 trie->n_entries++;
337
338 new_node->prefixlen = key->prefixlen;
339 RCU_INIT_POINTER(new_node->child[0], NULL);
340 RCU_INIT_POINTER(new_node->child[1], NULL);
341 memcpy(new_node->data, key->data, trie->data_size);
342
343 /* Now find a slot to attach the new node. To do that, walk the tree
344 * from the root and match as many bits as possible for each node until
345 * we either find an empty slot or a slot that needs to be replaced by
346 * an intermediate node.
347 */
348 slot = &trie->root;
349
350 while ((node = rcu_dereference_protected(*slot,
351 lockdep_is_held(&trie->lock)))) {
352 matchlen = longest_prefix_match(trie, node, key);
353
354 if (node->prefixlen != matchlen ||
355 node->prefixlen == key->prefixlen ||
356 node->prefixlen == trie->max_prefixlen)
357 break;
358
359 next_bit = extract_bit(key->data, node->prefixlen);
360 slot = &node->child[next_bit];
361 }
362
363 /* If the slot is empty (a free child pointer or an empty root),
364 * simply assign the @new_node to that slot and be done.
365 */
366 if (!node) {
367 rcu_assign_pointer(*slot, new_node);
368 goto out;
369 }
370
371 /* If the slot we picked already exists, replace it with @new_node
372 * which already has the correct data array set.
373 */
374 if (node->prefixlen == matchlen) {
375 new_node->child[0] = node->child[0];
376 new_node->child[1] = node->child[1];
377
378 if (!(node->flags & LPM_TREE_NODE_FLAG_IM))
379 trie->n_entries--;
380
381 rcu_assign_pointer(*slot, new_node);
382 kfree_rcu(node, rcu);
383
384 goto out;
385 }
386
387 /* If the new node matches the prefix completely, it must be inserted
388 * as an ancestor. Simply insert it between @node and *@slot.
389 */
390 if (matchlen == key->prefixlen) {
391 next_bit = extract_bit(node->data, matchlen);
392 rcu_assign_pointer(new_node->child[next_bit], node);
393 rcu_assign_pointer(*slot, new_node);
394 goto out;
395 }
396
397 im_node = lpm_trie_node_alloc(trie, NULL);
398 if (!im_node) {
399 ret = -ENOMEM;
400 goto out;
401 }
402
403 im_node->prefixlen = matchlen;
404 im_node->flags |= LPM_TREE_NODE_FLAG_IM;
405 memcpy(im_node->data, node->data, trie->data_size);
406
407 /* Now determine which child to install in which slot */
408 if (extract_bit(key->data, matchlen)) {
409 rcu_assign_pointer(im_node->child[0], node);
410 rcu_assign_pointer(im_node->child[1], new_node);
411 } else {
412 rcu_assign_pointer(im_node->child[0], new_node);
413 rcu_assign_pointer(im_node->child[1], node);
414 }
415
416 /* Finally, assign the intermediate node to the determined slot */
417 rcu_assign_pointer(*slot, im_node);
418
419out:
420 if (ret) {
421 if (new_node)
422 trie->n_entries--;
423
424 kfree(new_node);
425 kfree(im_node);
426 }
427
428 spin_unlock_irqrestore(&trie->lock, irq_flags);
429
430 return ret;
431}
432
433/* Called from syscall or from eBPF program */
434static int trie_delete_elem(struct bpf_map *map, void *_key)
435{
436 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
437 struct bpf_lpm_trie_key *key = _key;
438 struct lpm_trie_node __rcu **trim, **trim2;
439 struct lpm_trie_node *node, *parent;
440 unsigned long irq_flags;
441 unsigned int next_bit;
442 size_t matchlen = 0;
443 int ret = 0;
444
445 if (key->prefixlen > trie->max_prefixlen)
446 return -EINVAL;
447
448 spin_lock_irqsave(&trie->lock, irq_flags);
449
450 /* Walk the tree looking for an exact key/length match and keeping
451 * track of the path we traverse. We will need to know the node
452 * we wish to delete, and the slot that points to the node we want
453 * to delete. We may also need to know the nodes parent and the
454 * slot that contains it.
455 */
456 trim = &trie->root;
457 trim2 = trim;
458 parent = NULL;
459 while ((node = rcu_dereference_protected(
460 *trim, lockdep_is_held(&trie->lock)))) {
461 matchlen = longest_prefix_match(trie, node, key);
462
463 if (node->prefixlen != matchlen ||
464 node->prefixlen == key->prefixlen)
465 break;
466
467 parent = node;
468 trim2 = trim;
469 next_bit = extract_bit(key->data, node->prefixlen);
470 trim = &node->child[next_bit];
471 }
472
473 if (!node || node->prefixlen != key->prefixlen ||
474 node->prefixlen != matchlen ||
475 (node->flags & LPM_TREE_NODE_FLAG_IM)) {
476 ret = -ENOENT;
477 goto out;
478 }
479
480 trie->n_entries--;
481
482 /* If the node we are removing has two children, simply mark it
483 * as intermediate and we are done.
484 */
485 if (rcu_access_pointer(node->child[0]) &&
486 rcu_access_pointer(node->child[1])) {
487 node->flags |= LPM_TREE_NODE_FLAG_IM;
488 goto out;
489 }
490
491 /* If the parent of the node we are about to delete is an intermediate
492 * node, and the deleted node doesn't have any children, we can delete
493 * the intermediate parent as well and promote its other child
494 * up the tree. Doing this maintains the invariant that all
495 * intermediate nodes have exactly 2 children and that there are no
496 * unnecessary intermediate nodes in the tree.
497 */
498 if (parent && (parent->flags & LPM_TREE_NODE_FLAG_IM) &&
499 !node->child[0] && !node->child[1]) {
500 if (node == rcu_access_pointer(parent->child[0]))
501 rcu_assign_pointer(
502 *trim2, rcu_access_pointer(parent->child[1]));
503 else
504 rcu_assign_pointer(
505 *trim2, rcu_access_pointer(parent->child[0]));
506 kfree_rcu(parent, rcu);
507 kfree_rcu(node, rcu);
508 goto out;
509 }
510
511 /* The node we are removing has either zero or one child. If there
512 * is a child, move it into the removed node's slot then delete
513 * the node. Otherwise just clear the slot and delete the node.
514 */
515 if (node->child[0])
516 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[0]));
517 else if (node->child[1])
518 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[1]));
519 else
520 RCU_INIT_POINTER(*trim, NULL);
521 kfree_rcu(node, rcu);
522
523out:
524 spin_unlock_irqrestore(&trie->lock, irq_flags);
525
526 return ret;
527}
528
529#define LPM_DATA_SIZE_MAX 256
530#define LPM_DATA_SIZE_MIN 1
531
532#define LPM_VAL_SIZE_MAX (KMALLOC_MAX_SIZE - LPM_DATA_SIZE_MAX - \
533 sizeof(struct lpm_trie_node))
534#define LPM_VAL_SIZE_MIN 1
535
536#define LPM_KEY_SIZE(X) (sizeof(struct bpf_lpm_trie_key) + (X))
537#define LPM_KEY_SIZE_MAX LPM_KEY_SIZE(LPM_DATA_SIZE_MAX)
538#define LPM_KEY_SIZE_MIN LPM_KEY_SIZE(LPM_DATA_SIZE_MIN)
539
540#define LPM_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_NUMA_NODE | \
541 BPF_F_ACCESS_MASK)
542
543static struct bpf_map *trie_alloc(union bpf_attr *attr)
544{
545 struct lpm_trie *trie;
546
547 if (!bpf_capable())
548 return ERR_PTR(-EPERM);
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(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(-EINVAL);
560
561 trie = bpf_map_area_alloc(sizeof(*trie), NUMA_NO_NODE);
562 if (!trie)
563 return ERR_PTR(-ENOMEM);
564
565 /* copy mandatory map attributes */
566 bpf_map_init_from_attr(&trie->map, attr);
567 trie->data_size = attr->key_size -
568 offsetof(struct bpf_lpm_trie_key, 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(node);
606 RCU_INIT_POINTER(*slot, NULL);
607 break;
608 }
609 }
610
611out:
612 bpf_map_area_free(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 *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(trie->max_prefixlen,
646 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(key->data, 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, data),
707 next_node->data, trie->data_size);
708free_stack:
709 kfree(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 embedded. */
719 return BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ?
720 -EINVAL : 0;
721}
722
723BTF_ID_LIST_SINGLE(trie_map_btf_ids, struct, lpm_trie)
724const struct bpf_map_ops trie_map_ops = {
725 .map_meta_equal = bpf_map_meta_equal,
726 .map_alloc = trie_alloc,
727 .map_free = trie_free,
728 .map_get_next_key = trie_get_next_key,
729 .map_lookup_elem = trie_lookup_elem,
730 .map_update_elem = trie_update_elem,
731 .map_delete_elem = trie_delete_elem,
732 .map_lookup_batch = generic_map_lookup_batch,
733 .map_update_batch = generic_map_update_batch,
734 .map_delete_batch = generic_map_delete_batch,
735 .map_check_btf = trie_check_btf,
736 .map_btf_id = &trie_map_btf_ids[0],
737};
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
21struct lpm_trie_node;
22
23struct 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[];
29};
30
31struct 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 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
151static 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 */
164static 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 */
227static 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
276static 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 */
300static 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 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
416out:
417 if (ret) {
418 if (new_node)
419 trie->n_entries--;
420
421 kfree(new_node);
422 kfree(im_node);
423 }
424
425 spin_unlock_irqrestore(&trie->lock, irq_flags);
426
427 return ret;
428}
429
430/* Called from syscall or from eBPF program */
431static 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 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
520out:
521 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
540static 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 (!bpf_capable())
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 spin_lock_init(&trie->lock);
579
580 return &trie->map;
581out_err:
582 kfree(trie);
583 return ERR_PTR(ret);
584}
585
586static 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 /* Always start at the root and walk down to a node that has no
593 * children. Then free that node, nullify its reference in the parent
594 * and start over.
595 */
596
597 for (;;) {
598 slot = &trie->root;
599
600 for (;;) {
601 node = rcu_dereference_protected(*slot, 1);
602 if (!node)
603 goto out;
604
605 if (rcu_access_pointer(node->child[0])) {
606 slot = &node->child[0];
607 continue;
608 }
609
610 if (rcu_access_pointer(node->child[1])) {
611 slot = &node->child[1];
612 continue;
613 }
614
615 kfree(node);
616 RCU_INIT_POINTER(*slot, NULL);
617 break;
618 }
619 }
620
621out:
622 kfree(trie);
623}
624
625static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
626{
627 struct lpm_trie_node *node, *next_node = NULL, *parent, *search_root;
628 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
629 struct bpf_lpm_trie_key *key = _key, *next_key = _next_key;
630 struct lpm_trie_node **node_stack = NULL;
631 int err = 0, stack_ptr = -1;
632 unsigned int next_bit;
633 size_t matchlen;
634
635 /* The get_next_key follows postorder. For the 4 node example in
636 * the top of this file, the trie_get_next_key() returns the following
637 * one after another:
638 * 192.168.0.0/24
639 * 192.168.1.0/24
640 * 192.168.128.0/24
641 * 192.168.0.0/16
642 *
643 * The idea is to return more specific keys before less specific ones.
644 */
645
646 /* Empty trie */
647 search_root = rcu_dereference(trie->root);
648 if (!search_root)
649 return -ENOENT;
650
651 /* For invalid key, find the leftmost node in the trie */
652 if (!key || key->prefixlen > trie->max_prefixlen)
653 goto find_leftmost;
654
655 node_stack = kmalloc_array(trie->max_prefixlen,
656 sizeof(struct lpm_trie_node *),
657 GFP_ATOMIC | __GFP_NOWARN);
658 if (!node_stack)
659 return -ENOMEM;
660
661 /* Try to find the exact node for the given key */
662 for (node = search_root; node;) {
663 node_stack[++stack_ptr] = node;
664 matchlen = longest_prefix_match(trie, node, key);
665 if (node->prefixlen != matchlen ||
666 node->prefixlen == key->prefixlen)
667 break;
668
669 next_bit = extract_bit(key->data, node->prefixlen);
670 node = rcu_dereference(node->child[next_bit]);
671 }
672 if (!node || node->prefixlen != key->prefixlen ||
673 (node->flags & LPM_TREE_NODE_FLAG_IM))
674 goto find_leftmost;
675
676 /* The node with the exactly-matching key has been found,
677 * find the first node in postorder after the matched node.
678 */
679 node = node_stack[stack_ptr];
680 while (stack_ptr > 0) {
681 parent = node_stack[stack_ptr - 1];
682 if (rcu_dereference(parent->child[0]) == node) {
683 search_root = rcu_dereference(parent->child[1]);
684 if (search_root)
685 goto find_leftmost;
686 }
687 if (!(parent->flags & LPM_TREE_NODE_FLAG_IM)) {
688 next_node = parent;
689 goto do_copy;
690 }
691
692 node = parent;
693 stack_ptr--;
694 }
695
696 /* did not find anything */
697 err = -ENOENT;
698 goto free_stack;
699
700find_leftmost:
701 /* Find the leftmost non-intermediate node, all intermediate nodes
702 * have exact two children, so this function will never return NULL.
703 */
704 for (node = search_root; node;) {
705 if (node->flags & LPM_TREE_NODE_FLAG_IM) {
706 node = rcu_dereference(node->child[0]);
707 } else {
708 next_node = node;
709 node = rcu_dereference(node->child[0]);
710 if (!node)
711 node = rcu_dereference(next_node->child[1]);
712 }
713 }
714do_copy:
715 next_key->prefixlen = next_node->prefixlen;
716 memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key, data),
717 next_node->data, trie->data_size);
718free_stack:
719 kfree(node_stack);
720 return err;
721}
722
723static int trie_check_btf(const struct bpf_map *map,
724 const struct btf *btf,
725 const struct btf_type *key_type,
726 const struct btf_type *value_type)
727{
728 /* Keys must have struct bpf_lpm_trie_key embedded. */
729 return BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ?
730 -EINVAL : 0;
731}
732
733static int trie_map_btf_id;
734const struct bpf_map_ops trie_map_ops = {
735 .map_alloc = trie_alloc,
736 .map_free = trie_free,
737 .map_get_next_key = trie_get_next_key,
738 .map_lookup_elem = trie_lookup_elem,
739 .map_update_elem = trie_update_elem,
740 .map_delete_elem = trie_delete_elem,
741 .map_check_btf = trie_check_btf,
742 .map_btf_name = "lpm_trie",
743 .map_btf_id = &trie_map_btf_id,
744};