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 */ 150 151 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_check(trie->root, rcu_read_lock_bh_held()); 236 node;) { 237 unsigned int next_bit; 238 size_t matchlen; 239 240 /* Determine the longest prefix of @node that matches @key. 241 * If it's the maximum possible prefix for this trie, we have 242 * an exact match and can return it directly. 243 */ 244 matchlen = longest_prefix_match(trie, node, key); 245 if (matchlen == trie->max_prefixlen) { 246 found = node; 247 break; 248 } 249 250 /* If the number of bits that match is smaller than the prefix 251 * length of @node, bail out and return the node we have seen 252 * last in the traversal (ie, the parent). 253 */ 254 if (matchlen < node->prefixlen) 255 break; 256 257 /* Consider this node as return candidate unless it is an 258 * artificially added intermediate one. 259 */ 260 if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) 261 found = node; 262 263 /* If the node match is fully satisfied, let's see if we can 264 * become more specific. Determine the next bit in the key and 265 * traverse down. 266 */ 267 next_bit = extract_bit(key->data, node->prefixlen); 268 node = rcu_dereference_check(node->child[next_bit], 269 rcu_read_lock_bh_held()); 270 } 271 272 if (!found) 273 return NULL; 274 275 return found->data + trie->data_size; 276 } 277 278 static struct lpm_trie_node *lpm_trie_node_alloc(const struct lpm_trie *trie, 279 const void *value) 280 { 281 struct lpm_trie_node *node; 282 size_t size = sizeof(struct lpm_trie_node) + trie->data_size; 283 284 if (value) 285 size += trie->map.value_size; 286 287 node = bpf_map_kmalloc_node(&trie->map, size, GFP_ATOMIC | __GFP_NOWARN, 288 trie->map.numa_node); 289 if (!node) 290 return NULL; 291 292 node->flags = 0; 293 294 if (value) 295 memcpy(node->data + trie->data_size, value, 296 trie->map.value_size); 297 298 return node; 299 } 300 301 /* Called from syscall or from eBPF program */ 302 static int trie_update_elem(struct bpf_map *map, 303 void *_key, void *value, u64 flags) 304 { 305 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 306 struct lpm_trie_node *node, *im_node = NULL, *new_node = NULL; 307 struct lpm_trie_node __rcu **slot; 308 struct bpf_lpm_trie_key *key = _key; 309 unsigned long irq_flags; 310 unsigned int next_bit; 311 size_t matchlen = 0; 312 int ret = 0; 313 314 if (unlikely(flags > BPF_EXIST)) 315 return -EINVAL; 316 317 if (key->prefixlen > trie->max_prefixlen) 318 return -EINVAL; 319 320 spin_lock_irqsave(&trie->lock, irq_flags); 321 322 /* Allocate and fill a new node */ 323 324 if (trie->n_entries == trie->map.max_entries) { 325 ret = -ENOSPC; 326 goto out; 327 } 328 329 new_node = lpm_trie_node_alloc(trie, value); 330 if (!new_node) { 331 ret = -ENOMEM; 332 goto out; 333 } 334 335 trie->n_entries++; 336 337 new_node->prefixlen = key->prefixlen; 338 RCU_INIT_POINTER(new_node->child[0], NULL); 339 RCU_INIT_POINTER(new_node->child[1], NULL); 340 memcpy(new_node->data, key->data, trie->data_size); 341 342 /* Now find a slot to attach the new node. To do that, walk the tree 343 * from the root and match as many bits as possible for each node until 344 * we either find an empty slot or a slot that needs to be replaced by 345 * an intermediate node. 346 */ 347 slot = &trie->root; 348 349 while ((node = rcu_dereference_protected(*slot, 350 lockdep_is_held(&trie->lock)))) { 351 matchlen = longest_prefix_match(trie, node, key); 352 353 if (node->prefixlen != matchlen || 354 node->prefixlen == key->prefixlen || 355 node->prefixlen == trie->max_prefixlen) 356 break; 357 358 next_bit = extract_bit(key->data, node->prefixlen); 359 slot = &node->child[next_bit]; 360 } 361 362 /* If the slot is empty (a free child pointer or an empty root), 363 * simply assign the @new_node to that slot and be done. 364 */ 365 if (!node) { 366 rcu_assign_pointer(*slot, new_node); 367 goto out; 368 } 369 370 /* If the slot we picked already exists, replace it with @new_node 371 * which already has the correct data array set. 372 */ 373 if (node->prefixlen == matchlen) { 374 new_node->child[0] = node->child[0]; 375 new_node->child[1] = node->child[1]; 376 377 if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) 378 trie->n_entries--; 379 380 rcu_assign_pointer(*slot, new_node); 381 kfree_rcu(node, rcu); 382 383 goto out; 384 } 385 386 /* If the new node matches the prefix completely, it must be inserted 387 * as an ancestor. Simply insert it between @node and *@slot. 388 */ 389 if (matchlen == key->prefixlen) { 390 next_bit = extract_bit(node->data, matchlen); 391 rcu_assign_pointer(new_node->child[next_bit], node); 392 rcu_assign_pointer(*slot, new_node); 393 goto out; 394 } 395 396 im_node = lpm_trie_node_alloc(trie, NULL); 397 if (!im_node) { 398 ret = -ENOMEM; 399 goto out; 400 } 401 402 im_node->prefixlen = matchlen; 403 im_node->flags |= LPM_TREE_NODE_FLAG_IM; 404 memcpy(im_node->data, node->data, trie->data_size); 405 406 /* Now determine which child to install in which slot */ 407 if (extract_bit(key->data, matchlen)) { 408 rcu_assign_pointer(im_node->child[0], node); 409 rcu_assign_pointer(im_node->child[1], new_node); 410 } else { 411 rcu_assign_pointer(im_node->child[0], new_node); 412 rcu_assign_pointer(im_node->child[1], node); 413 } 414 415 /* Finally, assign the intermediate node to the determined spot */ 416 rcu_assign_pointer(*slot, im_node); 417 418 out: 419 if (ret) { 420 if (new_node) 421 trie->n_entries--; 422 423 kfree(new_node); 424 kfree(im_node); 425 } 426 427 spin_unlock_irqrestore(&trie->lock, irq_flags); 428 429 return ret; 430 } 431 432 /* Called from syscall or from eBPF program */ 433 static int trie_delete_elem(struct bpf_map *map, void *_key) 434 { 435 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 436 struct bpf_lpm_trie_key *key = _key; 437 struct lpm_trie_node __rcu **trim, **trim2; 438 struct lpm_trie_node *node, *parent; 439 unsigned long irq_flags; 440 unsigned int next_bit; 441 size_t matchlen = 0; 442 int ret = 0; 443 444 if (key->prefixlen > trie->max_prefixlen) 445 return -EINVAL; 446 447 spin_lock_irqsave(&trie->lock, irq_flags); 448 449 /* Walk the tree looking for an exact key/length match and keeping 450 * track of the path we traverse. We will need to know the node 451 * we wish to delete, and the slot that points to the node we want 452 * to delete. We may also need to know the nodes parent and the 453 * slot that contains it. 454 */ 455 trim = &trie->root; 456 trim2 = trim; 457 parent = NULL; 458 while ((node = rcu_dereference_protected( 459 *trim, lockdep_is_held(&trie->lock)))) { 460 matchlen = longest_prefix_match(trie, node, key); 461 462 if (node->prefixlen != matchlen || 463 node->prefixlen == key->prefixlen) 464 break; 465 466 parent = node; 467 trim2 = trim; 468 next_bit = extract_bit(key->data, node->prefixlen); 469 trim = &node->child[next_bit]; 470 } 471 472 if (!node || node->prefixlen != key->prefixlen || 473 node->prefixlen != matchlen || 474 (node->flags & LPM_TREE_NODE_FLAG_IM)) { 475 ret = -ENOENT; 476 goto out; 477 } 478 479 trie->n_entries--; 480 481 /* If the node we are removing has two children, simply mark it 482 * as intermediate and we are done. 483 */ 484 if (rcu_access_pointer(node->child[0]) && 485 rcu_access_pointer(node->child[1])) { 486 node->flags |= LPM_TREE_NODE_FLAG_IM; 487 goto out; 488 } 489 490 /* If the parent of the node we are about to delete is an intermediate 491 * node, and the deleted node doesn't have any children, we can delete 492 * the intermediate parent as well and promote its other child 493 * up the tree. Doing this maintains the invariant that all 494 * intermediate nodes have exactly 2 children and that there are no 495 * unnecessary intermediate nodes in the tree. 496 */ 497 if (parent && (parent->flags & LPM_TREE_NODE_FLAG_IM) && 498 !node->child[0] && !node->child[1]) { 499 if (node == rcu_access_pointer(parent->child[0])) 500 rcu_assign_pointer( 501 *trim2, rcu_access_pointer(parent->child[1])); 502 else 503 rcu_assign_pointer( 504 *trim2, rcu_access_pointer(parent->child[0])); 505 kfree_rcu(parent, rcu); 506 kfree_rcu(node, rcu); 507 goto out; 508 } 509 510 /* The node we are removing has either zero or one child. If there 511 * is a child, move it into the removed node's slot then delete 512 * the node. Otherwise just clear the slot and delete the node. 513 */ 514 if (node->child[0]) 515 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[0])); 516 else if (node->child[1]) 517 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[1])); 518 else 519 RCU_INIT_POINTER(*trim, NULL); 520 kfree_rcu(node, rcu); 521 522 out: 523 spin_unlock_irqrestore(&trie->lock, irq_flags); 524 525 return ret; 526 } 527 528 #define LPM_DATA_SIZE_MAX 256 529 #define LPM_DATA_SIZE_MIN 1 530 531 #define LPM_VAL_SIZE_MAX (KMALLOC_MAX_SIZE - LPM_DATA_SIZE_MAX - \ 532 sizeof(struct lpm_trie_node)) 533 #define LPM_VAL_SIZE_MIN 1 534 535 #define LPM_KEY_SIZE(X) (sizeof(struct bpf_lpm_trie_key) + (X)) 536 #define LPM_KEY_SIZE_MAX LPM_KEY_SIZE(LPM_DATA_SIZE_MAX) 537 #define LPM_KEY_SIZE_MIN LPM_KEY_SIZE(LPM_DATA_SIZE_MIN) 538 539 #define LPM_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_NUMA_NODE | \ 540 BPF_F_ACCESS_MASK) 541 542 static struct bpf_map *trie_alloc(union bpf_attr *attr) 543 { 544 struct lpm_trie *trie; 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 | __GFP_ACCOUNT); 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 spin_lock_init(&trie->lock); 571 572 return &trie->map; 573 } 574 575 static void trie_free(struct bpf_map *map) 576 { 577 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 578 struct lpm_trie_node __rcu **slot; 579 struct lpm_trie_node *node; 580 581 /* Always start at the root and walk down to a node that has no 582 * children. Then free that node, nullify its reference in the parent 583 * and start over. 584 */ 585 586 for (;;) { 587 slot = &trie->root; 588 589 for (;;) { 590 node = rcu_dereference_protected(*slot, 1); 591 if (!node) 592 goto out; 593 594 if (rcu_access_pointer(node->child[0])) { 595 slot = &node->child[0]; 596 continue; 597 } 598 599 if (rcu_access_pointer(node->child[1])) { 600 slot = &node->child[1]; 601 continue; 602 } 603 604 kfree(node); 605 RCU_INIT_POINTER(*slot, NULL); 606 break; 607 } 608 } 609 610 out: 611 kfree(trie); 612 } 613 614 static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key) 615 { 616 struct lpm_trie_node *node, *next_node = NULL, *parent, *search_root; 617 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 618 struct bpf_lpm_trie_key *key = _key, *next_key = _next_key; 619 struct lpm_trie_node **node_stack = NULL; 620 int err = 0, stack_ptr = -1; 621 unsigned int next_bit; 622 size_t matchlen; 623 624 /* The get_next_key follows postorder. For the 4 node example in 625 * the top of this file, the trie_get_next_key() returns the following 626 * one after another: 627 * 192.168.0.0/24 628 * 192.168.1.0/24 629 * 192.168.128.0/24 630 * 192.168.0.0/16 631 * 632 * The idea is to return more specific keys before less specific ones. 633 */ 634 635 /* Empty trie */ 636 search_root = rcu_dereference(trie->root); 637 if (!search_root) 638 return -ENOENT; 639 640 /* For invalid key, find the leftmost node in the trie */ 641 if (!key || key->prefixlen > trie->max_prefixlen) 642 goto find_leftmost; 643 644 node_stack = kmalloc_array(trie->max_prefixlen, 645 sizeof(struct lpm_trie_node *), 646 GFP_ATOMIC | __GFP_NOWARN); 647 if (!node_stack) 648 return -ENOMEM; 649 650 /* Try to find the exact node for the given key */ 651 for (node = search_root; node;) { 652 node_stack[++stack_ptr] = node; 653 matchlen = longest_prefix_match(trie, node, key); 654 if (node->prefixlen != matchlen || 655 node->prefixlen == key->prefixlen) 656 break; 657 658 next_bit = extract_bit(key->data, node->prefixlen); 659 node = rcu_dereference(node->child[next_bit]); 660 } 661 if (!node || node->prefixlen != key->prefixlen || 662 (node->flags & LPM_TREE_NODE_FLAG_IM)) 663 goto find_leftmost; 664 665 /* The node with the exactly-matching key has been found, 666 * find the first node in postorder after the matched node. 667 */ 668 node = node_stack[stack_ptr]; 669 while (stack_ptr > 0) { 670 parent = node_stack[stack_ptr - 1]; 671 if (rcu_dereference(parent->child[0]) == node) { 672 search_root = rcu_dereference(parent->child[1]); 673 if (search_root) 674 goto find_leftmost; 675 } 676 if (!(parent->flags & LPM_TREE_NODE_FLAG_IM)) { 677 next_node = parent; 678 goto do_copy; 679 } 680 681 node = parent; 682 stack_ptr--; 683 } 684 685 /* did not find anything */ 686 err = -ENOENT; 687 goto free_stack; 688 689 find_leftmost: 690 /* Find the leftmost non-intermediate node, all intermediate nodes 691 * have exact two children, so this function will never return NULL. 692 */ 693 for (node = search_root; node;) { 694 if (node->flags & LPM_TREE_NODE_FLAG_IM) { 695 node = rcu_dereference(node->child[0]); 696 } else { 697 next_node = node; 698 node = rcu_dereference(node->child[0]); 699 if (!node) 700 node = rcu_dereference(next_node->child[1]); 701 } 702 } 703 do_copy: 704 next_key->prefixlen = next_node->prefixlen; 705 memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key, data), 706 next_node->data, trie->data_size); 707 free_stack: 708 kfree(node_stack); 709 return err; 710 } 711 712 static int trie_check_btf(const struct bpf_map *map, 713 const struct btf *btf, 714 const struct btf_type *key_type, 715 const struct btf_type *value_type) 716 { 717 /* Keys must have struct bpf_lpm_trie_key embedded. */ 718 return BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ? 719 -EINVAL : 0; 720 } 721 722 static int trie_map_btf_id; 723 const struct bpf_map_ops trie_map_ops = { 724 .map_meta_equal = bpf_map_meta_equal, 725 .map_alloc = trie_alloc, 726 .map_free = trie_free, 727 .map_get_next_key = trie_get_next_key, 728 .map_lookup_elem = trie_lookup_elem, 729 .map_update_elem = trie_update_elem, 730 .map_delete_elem = trie_delete_elem, 731 .map_lookup_batch = generic_map_lookup_batch, 732 .map_update_batch = generic_map_update_batch, 733 .map_delete_batch = generic_map_delete_batch, 734 .map_check_btf = trie_check_btf, 735 .map_btf_name = "lpm_trie", 736 .map_btf_id = &trie_map_btf_id, 737 }; 738