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
22 struct lpm_trie_node;
23
24 struct 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
32 struct 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
extract_bit(const u8 * data,size_t index)152 static 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 */
longest_prefix_match(const struct lpm_trie * trie,const struct lpm_trie_node * node,const struct bpf_lpm_trie_key_u8 * key)165 static 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(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 */
trie_lookup_elem(struct bpf_map * map,void * _key)228 static 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(key->data, 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
lpm_trie_node_alloc(const struct lpm_trie * trie,const void * value)282 static 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(&trie->map, size, GFP_NOWAIT | __GFP_NOWARN,
292 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 */
trie_update_elem(struct bpf_map * map,void * _key,void * value,u64 flags)306 static 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 *free_node = NULL;
312 struct lpm_trie_node __rcu **slot;
313 struct bpf_lpm_trie_key_u8 *key = _key;
314 unsigned long irq_flags;
315 unsigned int next_bit;
316 size_t matchlen = 0;
317 int ret = 0;
318
319 if (unlikely(flags > BPF_EXIST))
320 return -EINVAL;
321
322 if (key->prefixlen > trie->max_prefixlen)
323 return -EINVAL;
324
325 spin_lock_irqsave(&trie->lock, irq_flags);
326
327 /* Allocate and fill a new node */
328
329 if (trie->n_entries == trie->map.max_entries) {
330 ret = -ENOSPC;
331 goto out;
332 }
333
334 new_node = lpm_trie_node_alloc(trie, value);
335 if (!new_node) {
336 ret = -ENOMEM;
337 goto out;
338 }
339
340 trie->n_entries++;
341
342 new_node->prefixlen = key->prefixlen;
343 RCU_INIT_POINTER(new_node->child[0], NULL);
344 RCU_INIT_POINTER(new_node->child[1], NULL);
345 memcpy(new_node->data, key->data, trie->data_size);
346
347 /* Now find a slot to attach the new node. To do that, walk the tree
348 * from the root and match as many bits as possible for each node until
349 * we either find an empty slot or a slot that needs to be replaced by
350 * an intermediate node.
351 */
352 slot = &trie->root;
353
354 while ((node = rcu_dereference_protected(*slot,
355 lockdep_is_held(&trie->lock)))) {
356 matchlen = longest_prefix_match(trie, node, key);
357
358 if (node->prefixlen != matchlen ||
359 node->prefixlen == key->prefixlen ||
360 node->prefixlen == trie->max_prefixlen)
361 break;
362
363 next_bit = extract_bit(key->data, node->prefixlen);
364 slot = &node->child[next_bit];
365 }
366
367 /* If the slot is empty (a free child pointer or an empty root),
368 * simply assign the @new_node to that slot and be done.
369 */
370 if (!node) {
371 rcu_assign_pointer(*slot, new_node);
372 goto out;
373 }
374
375 /* If the slot we picked already exists, replace it with @new_node
376 * which already has the correct data array set.
377 */
378 if (node->prefixlen == matchlen) {
379 new_node->child[0] = node->child[0];
380 new_node->child[1] = node->child[1];
381
382 if (!(node->flags & LPM_TREE_NODE_FLAG_IM))
383 trie->n_entries--;
384
385 rcu_assign_pointer(*slot, new_node);
386 free_node = node;
387
388 goto out;
389 }
390
391 /* If the new node matches the prefix completely, it must be inserted
392 * as an ancestor. Simply insert it between @node and *@slot.
393 */
394 if (matchlen == key->prefixlen) {
395 next_bit = extract_bit(node->data, matchlen);
396 rcu_assign_pointer(new_node->child[next_bit], node);
397 rcu_assign_pointer(*slot, new_node);
398 goto out;
399 }
400
401 im_node = lpm_trie_node_alloc(trie, NULL);
402 if (!im_node) {
403 ret = -ENOMEM;
404 goto out;
405 }
406
407 im_node->prefixlen = matchlen;
408 im_node->flags |= LPM_TREE_NODE_FLAG_IM;
409 memcpy(im_node->data, node->data, trie->data_size);
410
411 /* Now determine which child to install in which slot */
412 if (extract_bit(key->data, matchlen)) {
413 rcu_assign_pointer(im_node->child[0], node);
414 rcu_assign_pointer(im_node->child[1], new_node);
415 } else {
416 rcu_assign_pointer(im_node->child[0], new_node);
417 rcu_assign_pointer(im_node->child[1], node);
418 }
419
420 /* Finally, assign the intermediate node to the determined slot */
421 rcu_assign_pointer(*slot, im_node);
422
423 out:
424 if (ret) {
425 if (new_node)
426 trie->n_entries--;
427
428 kfree(new_node);
429 kfree(im_node);
430 }
431
432 spin_unlock_irqrestore(&trie->lock, irq_flags);
433 kfree_rcu(free_node, rcu);
434
435 return ret;
436 }
437
438 /* Called from syscall or from eBPF program */
trie_delete_elem(struct bpf_map * map,void * _key)439 static long trie_delete_elem(struct bpf_map *map, void *_key)
440 {
441 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
442 struct lpm_trie_node *free_node = NULL, *free_parent = NULL;
443 struct bpf_lpm_trie_key_u8 *key = _key;
444 struct lpm_trie_node __rcu **trim, **trim2;
445 struct lpm_trie_node *node, *parent;
446 unsigned long irq_flags;
447 unsigned int next_bit;
448 size_t matchlen = 0;
449 int ret = 0;
450
451 if (key->prefixlen > trie->max_prefixlen)
452 return -EINVAL;
453
454 spin_lock_irqsave(&trie->lock, irq_flags);
455
456 /* Walk the tree looking for an exact key/length match and keeping
457 * track of the path we traverse. We will need to know the node
458 * we wish to delete, and the slot that points to the node we want
459 * to delete. We may also need to know the nodes parent and the
460 * slot that contains it.
461 */
462 trim = &trie->root;
463 trim2 = trim;
464 parent = NULL;
465 while ((node = rcu_dereference_protected(
466 *trim, lockdep_is_held(&trie->lock)))) {
467 matchlen = longest_prefix_match(trie, node, key);
468
469 if (node->prefixlen != matchlen ||
470 node->prefixlen == key->prefixlen)
471 break;
472
473 parent = node;
474 trim2 = trim;
475 next_bit = extract_bit(key->data, node->prefixlen);
476 trim = &node->child[next_bit];
477 }
478
479 if (!node || node->prefixlen != key->prefixlen ||
480 node->prefixlen != matchlen ||
481 (node->flags & LPM_TREE_NODE_FLAG_IM)) {
482 ret = -ENOENT;
483 goto out;
484 }
485
486 trie->n_entries--;
487
488 /* If the node we are removing has two children, simply mark it
489 * as intermediate and we are done.
490 */
491 if (rcu_access_pointer(node->child[0]) &&
492 rcu_access_pointer(node->child[1])) {
493 node->flags |= LPM_TREE_NODE_FLAG_IM;
494 goto out;
495 }
496
497 /* If the parent of the node we are about to delete is an intermediate
498 * node, and the deleted node doesn't have any children, we can delete
499 * the intermediate parent as well and promote its other child
500 * up the tree. Doing this maintains the invariant that all
501 * intermediate nodes have exactly 2 children and that there are no
502 * unnecessary intermediate nodes in the tree.
503 */
504 if (parent && (parent->flags & LPM_TREE_NODE_FLAG_IM) &&
505 !node->child[0] && !node->child[1]) {
506 if (node == rcu_access_pointer(parent->child[0]))
507 rcu_assign_pointer(
508 *trim2, rcu_access_pointer(parent->child[1]));
509 else
510 rcu_assign_pointer(
511 *trim2, rcu_access_pointer(parent->child[0]));
512 free_parent = parent;
513 free_node = node;
514 goto out;
515 }
516
517 /* The node we are removing has either zero or one child. If there
518 * is a child, move it into the removed node's slot then delete
519 * the node. Otherwise just clear the slot and delete the node.
520 */
521 if (node->child[0])
522 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[0]));
523 else if (node->child[1])
524 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[1]));
525 else
526 RCU_INIT_POINTER(*trim, NULL);
527 free_node = node;
528
529 out:
530 spin_unlock_irqrestore(&trie->lock, irq_flags);
531 kfree_rcu(free_parent, rcu);
532 kfree_rcu(free_node, rcu);
533
534 return ret;
535 }
536
537 #define LPM_DATA_SIZE_MAX 256
538 #define LPM_DATA_SIZE_MIN 1
539
540 #define LPM_VAL_SIZE_MAX (KMALLOC_MAX_SIZE - LPM_DATA_SIZE_MAX - \
541 sizeof(struct lpm_trie_node))
542 #define LPM_VAL_SIZE_MIN 1
543
544 #define LPM_KEY_SIZE(X) (sizeof(struct bpf_lpm_trie_key_u8) + (X))
545 #define LPM_KEY_SIZE_MAX LPM_KEY_SIZE(LPM_DATA_SIZE_MAX)
546 #define LPM_KEY_SIZE_MIN LPM_KEY_SIZE(LPM_DATA_SIZE_MIN)
547
548 #define LPM_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_NUMA_NODE | \
549 BPF_F_ACCESS_MASK)
550
trie_alloc(union bpf_attr * attr)551 static struct bpf_map *trie_alloc(union bpf_attr *attr)
552 {
553 struct lpm_trie *trie;
554
555 /* check sanity of attributes */
556 if (attr->max_entries == 0 ||
557 !(attr->map_flags & BPF_F_NO_PREALLOC) ||
558 attr->map_flags & ~LPM_CREATE_FLAG_MASK ||
559 !bpf_map_flags_access_ok(attr->map_flags) ||
560 attr->key_size < LPM_KEY_SIZE_MIN ||
561 attr->key_size > LPM_KEY_SIZE_MAX ||
562 attr->value_size < LPM_VAL_SIZE_MIN ||
563 attr->value_size > LPM_VAL_SIZE_MAX)
564 return ERR_PTR(-EINVAL);
565
566 trie = bpf_map_area_alloc(sizeof(*trie), NUMA_NO_NODE);
567 if (!trie)
568 return ERR_PTR(-ENOMEM);
569
570 /* copy mandatory map attributes */
571 bpf_map_init_from_attr(&trie->map, attr);
572 trie->data_size = attr->key_size -
573 offsetof(struct bpf_lpm_trie_key_u8, data);
574 trie->max_prefixlen = trie->data_size * 8;
575
576 spin_lock_init(&trie->lock);
577
578 return &trie->map;
579 }
580
trie_free(struct bpf_map * map)581 static void trie_free(struct bpf_map *map)
582 {
583 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
584 struct lpm_trie_node __rcu **slot;
585 struct lpm_trie_node *node;
586
587 /* Always start at the root and walk down to a node that has no
588 * children. Then free that node, nullify its reference in the parent
589 * and start over.
590 */
591
592 for (;;) {
593 slot = &trie->root;
594
595 for (;;) {
596 node = rcu_dereference_protected(*slot, 1);
597 if (!node)
598 goto out;
599
600 if (rcu_access_pointer(node->child[0])) {
601 slot = &node->child[0];
602 continue;
603 }
604
605 if (rcu_access_pointer(node->child[1])) {
606 slot = &node->child[1];
607 continue;
608 }
609
610 kfree(node);
611 RCU_INIT_POINTER(*slot, NULL);
612 break;
613 }
614 }
615
616 out:
617 bpf_map_area_free(trie);
618 }
619
trie_get_next_key(struct bpf_map * map,void * _key,void * _next_key)620 static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key)
621 {
622 struct lpm_trie_node *node, *next_node = NULL, *parent, *search_root;
623 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
624 struct bpf_lpm_trie_key_u8 *key = _key, *next_key = _next_key;
625 struct lpm_trie_node **node_stack = NULL;
626 int err = 0, stack_ptr = -1;
627 unsigned int next_bit;
628 size_t matchlen;
629
630 /* The get_next_key follows postorder. For the 4 node example in
631 * the top of this file, the trie_get_next_key() returns the following
632 * one after another:
633 * 192.168.0.0/24
634 * 192.168.1.0/24
635 * 192.168.128.0/24
636 * 192.168.0.0/16
637 *
638 * The idea is to return more specific keys before less specific ones.
639 */
640
641 /* Empty trie */
642 search_root = rcu_dereference(trie->root);
643 if (!search_root)
644 return -ENOENT;
645
646 /* For invalid key, find the leftmost node in the trie */
647 if (!key || key->prefixlen > trie->max_prefixlen)
648 goto find_leftmost;
649
650 node_stack = kmalloc_array(trie->max_prefixlen,
651 sizeof(struct lpm_trie_node *),
652 GFP_ATOMIC | __GFP_NOWARN);
653 if (!node_stack)
654 return -ENOMEM;
655
656 /* Try to find the exact node for the given key */
657 for (node = search_root; node;) {
658 node_stack[++stack_ptr] = node;
659 matchlen = longest_prefix_match(trie, node, key);
660 if (node->prefixlen != matchlen ||
661 node->prefixlen == key->prefixlen)
662 break;
663
664 next_bit = extract_bit(key->data, node->prefixlen);
665 node = rcu_dereference(node->child[next_bit]);
666 }
667 if (!node || node->prefixlen != key->prefixlen ||
668 (node->flags & LPM_TREE_NODE_FLAG_IM))
669 goto find_leftmost;
670
671 /* The node with the exactly-matching key has been found,
672 * find the first node in postorder after the matched node.
673 */
674 node = node_stack[stack_ptr];
675 while (stack_ptr > 0) {
676 parent = node_stack[stack_ptr - 1];
677 if (rcu_dereference(parent->child[0]) == node) {
678 search_root = rcu_dereference(parent->child[1]);
679 if (search_root)
680 goto find_leftmost;
681 }
682 if (!(parent->flags & LPM_TREE_NODE_FLAG_IM)) {
683 next_node = parent;
684 goto do_copy;
685 }
686
687 node = parent;
688 stack_ptr--;
689 }
690
691 /* did not find anything */
692 err = -ENOENT;
693 goto free_stack;
694
695 find_leftmost:
696 /* Find the leftmost non-intermediate node, all intermediate nodes
697 * have exact two children, so this function will never return NULL.
698 */
699 for (node = search_root; node;) {
700 if (node->flags & LPM_TREE_NODE_FLAG_IM) {
701 node = rcu_dereference(node->child[0]);
702 } else {
703 next_node = node;
704 node = rcu_dereference(node->child[0]);
705 if (!node)
706 node = rcu_dereference(next_node->child[1]);
707 }
708 }
709 do_copy:
710 next_key->prefixlen = next_node->prefixlen;
711 memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key_u8, data),
712 next_node->data, trie->data_size);
713 free_stack:
714 kfree(node_stack);
715 return err;
716 }
717
trie_check_btf(const struct bpf_map * map,const struct btf * btf,const struct btf_type * key_type,const struct btf_type * value_type)718 static int trie_check_btf(const struct bpf_map *map,
719 const struct btf *btf,
720 const struct btf_type *key_type,
721 const struct btf_type *value_type)
722 {
723 /* Keys must have struct bpf_lpm_trie_key_u8 embedded. */
724 return BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ?
725 -EINVAL : 0;
726 }
727
trie_mem_usage(const struct bpf_map * map)728 static u64 trie_mem_usage(const struct bpf_map *map)
729 {
730 struct lpm_trie *trie = container_of(map, struct lpm_trie, map);
731 u64 elem_size;
732
733 elem_size = sizeof(struct lpm_trie_node) + trie->data_size +
734 trie->map.value_size;
735 return elem_size * READ_ONCE(trie->n_entries);
736 }
737
738 BTF_ID_LIST_SINGLE(trie_map_btf_ids, struct, lpm_trie)
739 const struct bpf_map_ops trie_map_ops = {
740 .map_meta_equal = bpf_map_meta_equal,
741 .map_alloc = trie_alloc,
742 .map_free = trie_free,
743 .map_get_next_key = trie_get_next_key,
744 .map_lookup_elem = trie_lookup_elem,
745 .map_update_elem = trie_update_elem,
746 .map_delete_elem = trie_delete_elem,
747 .map_lookup_batch = generic_map_lookup_batch,
748 .map_update_batch = generic_map_update_batch,
749 .map_delete_batch = generic_map_delete_batch,
750 .map_check_btf = trie_check_btf,
751 .map_mem_usage = trie_mem_usage,
752 .map_btf_id = &trie_map_btf_ids[0],
753 };
754