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(trie->root); node;) { 236 unsigned int next_bit; 237 size_t matchlen; 238 239 /* Determine the longest prefix of @node that matches @key. 240 * If it's the maximum possible prefix for this trie, we have 241 * an exact match and can return it directly. 242 */ 243 matchlen = longest_prefix_match(trie, node, key); 244 if (matchlen == trie->max_prefixlen) { 245 found = node; 246 break; 247 } 248 249 /* If the number of bits that match is smaller than the prefix 250 * length of @node, bail out and return the node we have seen 251 * last in the traversal (ie, the parent). 252 */ 253 if (matchlen < node->prefixlen) 254 break; 255 256 /* Consider this node as return candidate unless it is an 257 * artificially added intermediate one. 258 */ 259 if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) 260 found = node; 261 262 /* If the node match is fully satisfied, let's see if we can 263 * become more specific. Determine the next bit in the key and 264 * traverse down. 265 */ 266 next_bit = extract_bit(key->data, node->prefixlen); 267 node = rcu_dereference(node->child[next_bit]); 268 } 269 270 if (!found) 271 return NULL; 272 273 return found->data + trie->data_size; 274 } 275 276 static struct lpm_trie_node *lpm_trie_node_alloc(const struct lpm_trie *trie, 277 const void *value) 278 { 279 struct lpm_trie_node *node; 280 size_t size = sizeof(struct lpm_trie_node) + trie->data_size; 281 282 if (value) 283 size += trie->map.value_size; 284 285 node = kmalloc_node(size, GFP_ATOMIC | __GFP_NOWARN, 286 trie->map.numa_node); 287 if (!node) 288 return NULL; 289 290 node->flags = 0; 291 292 if (value) 293 memcpy(node->data + trie->data_size, value, 294 trie->map.value_size); 295 296 return node; 297 } 298 299 /* Called from syscall or from eBPF program */ 300 static int trie_update_elem(struct bpf_map *map, 301 void *_key, void *value, u64 flags) 302 { 303 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 304 struct lpm_trie_node *node, *im_node = NULL, *new_node = NULL; 305 struct lpm_trie_node __rcu **slot; 306 struct bpf_lpm_trie_key *key = _key; 307 unsigned long irq_flags; 308 unsigned int next_bit; 309 size_t matchlen = 0; 310 int ret = 0; 311 312 if (unlikely(flags > BPF_EXIST)) 313 return -EINVAL; 314 315 if (key->prefixlen > trie->max_prefixlen) 316 return -EINVAL; 317 318 spin_lock_irqsave(&trie->lock, irq_flags); 319 320 /* Allocate and fill a new node */ 321 322 if (trie->n_entries == trie->map.max_entries) { 323 ret = -ENOSPC; 324 goto out; 325 } 326 327 new_node = lpm_trie_node_alloc(trie, value); 328 if (!new_node) { 329 ret = -ENOMEM; 330 goto out; 331 } 332 333 trie->n_entries++; 334 335 new_node->prefixlen = key->prefixlen; 336 RCU_INIT_POINTER(new_node->child[0], NULL); 337 RCU_INIT_POINTER(new_node->child[1], NULL); 338 memcpy(new_node->data, key->data, trie->data_size); 339 340 /* Now find a slot to attach the new node. To do that, walk the tree 341 * from the root and match as many bits as possible for each node until 342 * we either find an empty slot or a slot that needs to be replaced by 343 * an intermediate node. 344 */ 345 slot = &trie->root; 346 347 while ((node = rcu_dereference_protected(*slot, 348 lockdep_is_held(&trie->lock)))) { 349 matchlen = longest_prefix_match(trie, node, key); 350 351 if (node->prefixlen != matchlen || 352 node->prefixlen == key->prefixlen || 353 node->prefixlen == trie->max_prefixlen) 354 break; 355 356 next_bit = extract_bit(key->data, node->prefixlen); 357 slot = &node->child[next_bit]; 358 } 359 360 /* If the slot is empty (a free child pointer or an empty root), 361 * simply assign the @new_node to that slot and be done. 362 */ 363 if (!node) { 364 rcu_assign_pointer(*slot, new_node); 365 goto out; 366 } 367 368 /* If the slot we picked already exists, replace it with @new_node 369 * which already has the correct data array set. 370 */ 371 if (node->prefixlen == matchlen) { 372 new_node->child[0] = node->child[0]; 373 new_node->child[1] = node->child[1]; 374 375 if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) 376 trie->n_entries--; 377 378 rcu_assign_pointer(*slot, new_node); 379 kfree_rcu(node, rcu); 380 381 goto out; 382 } 383 384 /* If the new node matches the prefix completely, it must be inserted 385 * as an ancestor. Simply insert it between @node and *@slot. 386 */ 387 if (matchlen == key->prefixlen) { 388 next_bit = extract_bit(node->data, matchlen); 389 rcu_assign_pointer(new_node->child[next_bit], node); 390 rcu_assign_pointer(*slot, new_node); 391 goto out; 392 } 393 394 im_node = lpm_trie_node_alloc(trie, NULL); 395 if (!im_node) { 396 ret = -ENOMEM; 397 goto out; 398 } 399 400 im_node->prefixlen = matchlen; 401 im_node->flags |= LPM_TREE_NODE_FLAG_IM; 402 memcpy(im_node->data, node->data, trie->data_size); 403 404 /* Now determine which child to install in which slot */ 405 if (extract_bit(key->data, matchlen)) { 406 rcu_assign_pointer(im_node->child[0], node); 407 rcu_assign_pointer(im_node->child[1], new_node); 408 } else { 409 rcu_assign_pointer(im_node->child[0], new_node); 410 rcu_assign_pointer(im_node->child[1], node); 411 } 412 413 /* Finally, assign the intermediate node to the determined spot */ 414 rcu_assign_pointer(*slot, im_node); 415 416 out: 417 if (ret) { 418 if (new_node) 419 trie->n_entries--; 420 421 kfree(new_node); 422 kfree(im_node); 423 } 424 425 spin_unlock_irqrestore(&trie->lock, irq_flags); 426 427 return ret; 428 } 429 430 /* Called from syscall or from eBPF program */ 431 static int trie_delete_elem(struct bpf_map *map, void *_key) 432 { 433 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 434 struct bpf_lpm_trie_key *key = _key; 435 struct lpm_trie_node __rcu **trim, **trim2; 436 struct lpm_trie_node *node, *parent; 437 unsigned long irq_flags; 438 unsigned int next_bit; 439 size_t matchlen = 0; 440 int ret = 0; 441 442 if (key->prefixlen > trie->max_prefixlen) 443 return -EINVAL; 444 445 spin_lock_irqsave(&trie->lock, irq_flags); 446 447 /* Walk the tree looking for an exact key/length match and keeping 448 * track of the path we traverse. We will need to know the node 449 * we wish to delete, and the slot that points to the node we want 450 * to delete. We may also need to know the nodes parent and the 451 * slot that contains it. 452 */ 453 trim = &trie->root; 454 trim2 = trim; 455 parent = NULL; 456 while ((node = rcu_dereference_protected( 457 *trim, lockdep_is_held(&trie->lock)))) { 458 matchlen = longest_prefix_match(trie, node, key); 459 460 if (node->prefixlen != matchlen || 461 node->prefixlen == key->prefixlen) 462 break; 463 464 parent = node; 465 trim2 = trim; 466 next_bit = extract_bit(key->data, node->prefixlen); 467 trim = &node->child[next_bit]; 468 } 469 470 if (!node || node->prefixlen != key->prefixlen || 471 node->prefixlen != matchlen || 472 (node->flags & LPM_TREE_NODE_FLAG_IM)) { 473 ret = -ENOENT; 474 goto out; 475 } 476 477 trie->n_entries--; 478 479 /* If the node we are removing has two children, simply mark it 480 * as intermediate and we are done. 481 */ 482 if (rcu_access_pointer(node->child[0]) && 483 rcu_access_pointer(node->child[1])) { 484 node->flags |= LPM_TREE_NODE_FLAG_IM; 485 goto out; 486 } 487 488 /* If the parent of the node we are about to delete is an intermediate 489 * node, and the deleted node doesn't have any children, we can delete 490 * the intermediate parent as well and promote its other child 491 * up the tree. Doing this maintains the invariant that all 492 * intermediate nodes have exactly 2 children and that there are no 493 * unnecessary intermediate nodes in the tree. 494 */ 495 if (parent && (parent->flags & LPM_TREE_NODE_FLAG_IM) && 496 !node->child[0] && !node->child[1]) { 497 if (node == rcu_access_pointer(parent->child[0])) 498 rcu_assign_pointer( 499 *trim2, rcu_access_pointer(parent->child[1])); 500 else 501 rcu_assign_pointer( 502 *trim2, rcu_access_pointer(parent->child[0])); 503 kfree_rcu(parent, rcu); 504 kfree_rcu(node, rcu); 505 goto out; 506 } 507 508 /* The node we are removing has either zero or one child. If there 509 * is a child, move it into the removed node's slot then delete 510 * the node. Otherwise just clear the slot and delete the node. 511 */ 512 if (node->child[0]) 513 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[0])); 514 else if (node->child[1]) 515 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[1])); 516 else 517 RCU_INIT_POINTER(*trim, NULL); 518 kfree_rcu(node, rcu); 519 520 out: 521 spin_unlock_irqrestore(&trie->lock, irq_flags); 522 523 return ret; 524 } 525 526 #define LPM_DATA_SIZE_MAX 256 527 #define LPM_DATA_SIZE_MIN 1 528 529 #define LPM_VAL_SIZE_MAX (KMALLOC_MAX_SIZE - LPM_DATA_SIZE_MAX - \ 530 sizeof(struct lpm_trie_node)) 531 #define LPM_VAL_SIZE_MIN 1 532 533 #define LPM_KEY_SIZE(X) (sizeof(struct bpf_lpm_trie_key) + (X)) 534 #define LPM_KEY_SIZE_MAX LPM_KEY_SIZE(LPM_DATA_SIZE_MAX) 535 #define LPM_KEY_SIZE_MIN LPM_KEY_SIZE(LPM_DATA_SIZE_MIN) 536 537 #define LPM_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_NUMA_NODE | \ 538 BPF_F_ACCESS_MASK) 539 540 static struct bpf_map *trie_alloc(union bpf_attr *attr) 541 { 542 struct lpm_trie *trie; 543 u64 cost = sizeof(*trie), cost_per_node; 544 int ret; 545 546 if (!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; 581 out_err: 582 kfree(trie); 583 return ERR_PTR(ret); 584 } 585 586 static void trie_free(struct bpf_map *map) 587 { 588 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 589 struct lpm_trie_node __rcu **slot; 590 struct lpm_trie_node *node; 591 592 /* Wait for outstanding programs to complete 593 * update/lookup/delete/get_next_key and free the trie. 594 */ 595 synchronize_rcu(); 596 597 /* Always start at the root and walk down to a node that has no 598 * children. Then free that node, nullify its reference in the parent 599 * and start over. 600 */ 601 602 for (;;) { 603 slot = &trie->root; 604 605 for (;;) { 606 node = rcu_dereference_protected(*slot, 1); 607 if (!node) 608 goto out; 609 610 if (rcu_access_pointer(node->child[0])) { 611 slot = &node->child[0]; 612 continue; 613 } 614 615 if (rcu_access_pointer(node->child[1])) { 616 slot = &node->child[1]; 617 continue; 618 } 619 620 kfree(node); 621 RCU_INIT_POINTER(*slot, NULL); 622 break; 623 } 624 } 625 626 out: 627 kfree(trie); 628 } 629 630 static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key) 631 { 632 struct lpm_trie_node *node, *next_node = NULL, *parent, *search_root; 633 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 634 struct bpf_lpm_trie_key *key = _key, *next_key = _next_key; 635 struct lpm_trie_node **node_stack = NULL; 636 int err = 0, stack_ptr = -1; 637 unsigned int next_bit; 638 size_t matchlen; 639 640 /* The get_next_key follows postorder. For the 4 node example in 641 * the top of this file, the trie_get_next_key() returns the following 642 * one after another: 643 * 192.168.0.0/24 644 * 192.168.1.0/24 645 * 192.168.128.0/24 646 * 192.168.0.0/16 647 * 648 * The idea is to return more specific keys before less specific ones. 649 */ 650 651 /* Empty trie */ 652 search_root = rcu_dereference(trie->root); 653 if (!search_root) 654 return -ENOENT; 655 656 /* For invalid key, find the leftmost node in the trie */ 657 if (!key || key->prefixlen > trie->max_prefixlen) 658 goto find_leftmost; 659 660 node_stack = kmalloc_array(trie->max_prefixlen, 661 sizeof(struct lpm_trie_node *), 662 GFP_ATOMIC | __GFP_NOWARN); 663 if (!node_stack) 664 return -ENOMEM; 665 666 /* Try to find the exact node for the given key */ 667 for (node = search_root; node;) { 668 node_stack[++stack_ptr] = node; 669 matchlen = longest_prefix_match(trie, node, key); 670 if (node->prefixlen != matchlen || 671 node->prefixlen == key->prefixlen) 672 break; 673 674 next_bit = extract_bit(key->data, node->prefixlen); 675 node = rcu_dereference(node->child[next_bit]); 676 } 677 if (!node || node->prefixlen != key->prefixlen || 678 (node->flags & LPM_TREE_NODE_FLAG_IM)) 679 goto find_leftmost; 680 681 /* The node with the exactly-matching key has been found, 682 * find the first node in postorder after the matched node. 683 */ 684 node = node_stack[stack_ptr]; 685 while (stack_ptr > 0) { 686 parent = node_stack[stack_ptr - 1]; 687 if (rcu_dereference(parent->child[0]) == node) { 688 search_root = rcu_dereference(parent->child[1]); 689 if (search_root) 690 goto find_leftmost; 691 } 692 if (!(parent->flags & LPM_TREE_NODE_FLAG_IM)) { 693 next_node = parent; 694 goto do_copy; 695 } 696 697 node = parent; 698 stack_ptr--; 699 } 700 701 /* did not find anything */ 702 err = -ENOENT; 703 goto free_stack; 704 705 find_leftmost: 706 /* Find the leftmost non-intermediate node, all intermediate nodes 707 * have exact two children, so this function will never return NULL. 708 */ 709 for (node = search_root; node;) { 710 if (node->flags & LPM_TREE_NODE_FLAG_IM) { 711 node = rcu_dereference(node->child[0]); 712 } else { 713 next_node = node; 714 node = rcu_dereference(node->child[0]); 715 if (!node) 716 node = rcu_dereference(next_node->child[1]); 717 } 718 } 719 do_copy: 720 next_key->prefixlen = next_node->prefixlen; 721 memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key, data), 722 next_node->data, trie->data_size); 723 free_stack: 724 kfree(node_stack); 725 return err; 726 } 727 728 static int trie_check_btf(const struct bpf_map *map, 729 const struct btf *btf, 730 const struct btf_type *key_type, 731 const struct btf_type *value_type) 732 { 733 /* Keys must have struct bpf_lpm_trie_key embedded. */ 734 return BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ? 735 -EINVAL : 0; 736 } 737 738 const struct bpf_map_ops trie_map_ops = { 739 .map_alloc = trie_alloc, 740 .map_free = trie_free, 741 .map_get_next_key = trie_get_next_key, 742 .map_lookup_elem = trie_lookup_elem, 743 .map_update_elem = trie_update_elem, 744 .map_delete_elem = trie_delete_elem, 745 .map_check_btf = trie_check_btf, 746 }; 747