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[];
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 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
extract_bit(const u8 * data,size_t index)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 */
longest_prefix_match(const struct lpm_trie * trie,const struct lpm_trie_node * node,const struct bpf_lpm_trie_key * key)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 */
trie_lookup_elem(struct bpf_map * map,void * _key)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 if (key->prefixlen > trie->max_prefixlen)
234 return NULL;
235
236 /* Start walking the trie from the root node ... */
237
238 for (node = rcu_dereference(trie->root); node;) {
239 unsigned int next_bit;
240 size_t matchlen;
241
242 /* Determine the longest prefix of @node that matches @key.
243 * If it's the maximum possible prefix for this trie, we have
244 * an exact match and can return it directly.
245 */
246 matchlen = longest_prefix_match(trie, node, key);
247 if (matchlen == trie->max_prefixlen) {
248 found = node;
249 break;
250 }
251
252 /* If the number of bits that match is smaller than the prefix
253 * length of @node, bail out and return the node we have seen
254 * last in the traversal (ie, the parent).
255 */
256 if (matchlen < node->prefixlen)
257 break;
258
259 /* Consider this node as return candidate unless it is an
260 * artificially added intermediate one.
261 */
262 if (!(node->flags & LPM_TREE_NODE_FLAG_IM))
263 found = node;
264
265 /* If the node match is fully satisfied, let's see if we can
266 * become more specific. Determine the next bit in the key and
267 * traverse down.
268 */
269 next_bit = extract_bit(key->data, node->prefixlen);
270 node = rcu_dereference(node->child[next_bit]);
271 }
272
273 if (!found)
274 return NULL;
275
276 return found->data + trie->data_size;
277 }
278
lpm_trie_node_alloc(const struct lpm_trie * trie,const void * value)279 static 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 = kmalloc_node(size, GFP_ATOMIC | __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 */
trie_update_elem(struct bpf_map * map,void * _key,void * value,u64 flags)303 static 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 spot */
417 rcu_assign_pointer(*slot, im_node);
418
419 out:
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 */
trie_delete_elem(struct bpf_map * map,void * _key)434 static 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
523 out:
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
trie_alloc(union bpf_attr * attr)543 static struct bpf_map *trie_alloc(union bpf_attr *attr)
544 {
545 struct lpm_trie *trie;
546 u64 cost = sizeof(*trie), cost_per_node;
547 int ret;
548
549 if (!bpf_capable())
550 return ERR_PTR(-EPERM);
551
552 /* check sanity of attributes */
553 if (attr->max_entries == 0 ||
554 !(attr->map_flags & BPF_F_NO_PREALLOC) ||
555 attr->map_flags & ~LPM_CREATE_FLAG_MASK ||
556 !bpf_map_flags_access_ok(attr->map_flags) ||
557 attr->key_size < LPM_KEY_SIZE_MIN ||
558 attr->key_size > LPM_KEY_SIZE_MAX ||
559 attr->value_size < LPM_VAL_SIZE_MIN ||
560 attr->value_size > LPM_VAL_SIZE_MAX)
561 return ERR_PTR(-EINVAL);
562
563 trie = kzalloc(sizeof(*trie), GFP_USER | __GFP_NOWARN);
564 if (!trie)
565 return ERR_PTR(-ENOMEM);
566
567 /* copy mandatory map attributes */
568 bpf_map_init_from_attr(&trie->map, attr);
569 trie->data_size = attr->key_size -
570 offsetof(struct bpf_lpm_trie_key, data);
571 trie->max_prefixlen = trie->data_size * 8;
572
573 cost_per_node = sizeof(struct lpm_trie_node) +
574 attr->value_size + trie->data_size;
575 cost += (u64) attr->max_entries * cost_per_node;
576
577 ret = bpf_map_charge_init(&trie->map.memory, cost);
578 if (ret)
579 goto out_err;
580
581 spin_lock_init(&trie->lock);
582
583 return &trie->map;
584 out_err:
585 kfree(trie);
586 return ERR_PTR(ret);
587 }
588
trie_free(struct bpf_map * map)589 static void trie_free(struct bpf_map *map)
590 {
591 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
592 struct lpm_trie_node __rcu **slot;
593 struct lpm_trie_node *node;
594
595 /* Always start at the root and walk down to a node that has no
596 * children. Then free that node, nullify its reference in the parent
597 * and start over.
598 */
599
600 for (;;) {
601 slot = &trie->root;
602
603 for (;;) {
604 node = rcu_dereference_protected(*slot, 1);
605 if (!node)
606 goto out;
607
608 if (rcu_access_pointer(node->child[0])) {
609 slot = &node->child[0];
610 continue;
611 }
612
613 if (rcu_access_pointer(node->child[1])) {
614 slot = &node->child[1];
615 continue;
616 }
617
618 kfree(node);
619 RCU_INIT_POINTER(*slot, NULL);
620 break;
621 }
622 }
623
624 out:
625 kfree(trie);
626 }
627
trie_get_next_key(struct bpf_map * map,void * _key,void * _next_key)628 static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
629 {
630 struct lpm_trie_node *node, *next_node = NULL, *parent, *search_root;
631 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
632 struct bpf_lpm_trie_key *key = _key, *next_key = _next_key;
633 struct lpm_trie_node **node_stack = NULL;
634 int err = 0, stack_ptr = -1;
635 unsigned int next_bit;
636 size_t matchlen;
637
638 /* The get_next_key follows postorder. For the 4 node example in
639 * the top of this file, the trie_get_next_key() returns the following
640 * one after another:
641 * 192.168.0.0/24
642 * 192.168.1.0/24
643 * 192.168.128.0/24
644 * 192.168.0.0/16
645 *
646 * The idea is to return more specific keys before less specific ones.
647 */
648
649 /* Empty trie */
650 search_root = rcu_dereference(trie->root);
651 if (!search_root)
652 return -ENOENT;
653
654 /* For invalid key, find the leftmost node in the trie */
655 if (!key || key->prefixlen > trie->max_prefixlen)
656 goto find_leftmost;
657
658 node_stack = kmalloc_array(trie->max_prefixlen,
659 sizeof(struct lpm_trie_node *),
660 GFP_ATOMIC | __GFP_NOWARN);
661 if (!node_stack)
662 return -ENOMEM;
663
664 /* Try to find the exact node for the given key */
665 for (node = search_root; node;) {
666 node_stack[++stack_ptr] = node;
667 matchlen = longest_prefix_match(trie, node, key);
668 if (node->prefixlen != matchlen ||
669 node->prefixlen == key->prefixlen)
670 break;
671
672 next_bit = extract_bit(key->data, node->prefixlen);
673 node = rcu_dereference(node->child[next_bit]);
674 }
675 if (!node || node->prefixlen != key->prefixlen ||
676 (node->flags & LPM_TREE_NODE_FLAG_IM))
677 goto find_leftmost;
678
679 /* The node with the exactly-matching key has been found,
680 * find the first node in postorder after the matched node.
681 */
682 node = node_stack[stack_ptr];
683 while (stack_ptr > 0) {
684 parent = node_stack[stack_ptr - 1];
685 if (rcu_dereference(parent->child[0]) == node) {
686 search_root = rcu_dereference(parent->child[1]);
687 if (search_root)
688 goto find_leftmost;
689 }
690 if (!(parent->flags & LPM_TREE_NODE_FLAG_IM)) {
691 next_node = parent;
692 goto do_copy;
693 }
694
695 node = parent;
696 stack_ptr--;
697 }
698
699 /* did not find anything */
700 err = -ENOENT;
701 goto free_stack;
702
703 find_leftmost:
704 /* Find the leftmost non-intermediate node, all intermediate nodes
705 * have exact two children, so this function will never return NULL.
706 */
707 for (node = search_root; node;) {
708 if (node->flags & LPM_TREE_NODE_FLAG_IM) {
709 node = rcu_dereference(node->child[0]);
710 } else {
711 next_node = node;
712 node = rcu_dereference(node->child[0]);
713 if (!node)
714 node = rcu_dereference(next_node->child[1]);
715 }
716 }
717 do_copy:
718 next_key->prefixlen = next_node->prefixlen;
719 memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key, data),
720 next_node->data, trie->data_size);
721 free_stack:
722 kfree(node_stack);
723 return err;
724 }
725
trie_check_btf(const struct bpf_map * map,const struct btf * btf,const struct btf_type * key_type,const struct btf_type * value_type)726 static int trie_check_btf(const struct bpf_map *map,
727 const struct btf *btf,
728 const struct btf_type *key_type,
729 const struct btf_type *value_type)
730 {
731 /* Keys must have struct bpf_lpm_trie_key embedded. */
732 return BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ?
733 -EINVAL : 0;
734 }
735
736 static int trie_map_btf_id;
737 const struct bpf_map_ops trie_map_ops = {
738 .map_meta_equal = bpf_map_meta_equal,
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 .map_btf_name = "lpm_trie",
747 .map_btf_id = &trie_map_btf_id,
748 };
749