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 */ 151 152 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 */ 165 static __always_inline 166 size_t __longest_prefix_match(const struct lpm_trie *trie, 167 const struct lpm_trie_node *node, 168 const struct bpf_lpm_trie_key_u8 *key) 169 { 170 u32 limit = min(node->prefixlen, key->prefixlen); 171 u32 prefixlen = 0, i = 0; 172 173 BUILD_BUG_ON(offsetof(struct lpm_trie_node, data) % sizeof(u32)); 174 BUILD_BUG_ON(offsetof(struct bpf_lpm_trie_key_u8, data) % sizeof(u32)); 175 176 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && defined(CONFIG_64BIT) 177 178 /* data_size >= 16 has very small probability. 179 * We do not use a loop for optimal code generation. 180 */ 181 if (trie->data_size >= 8) { 182 u64 diff = be64_to_cpu(*(__be64 *)node->data ^ 183 *(__be64 *)key->data); 184 185 prefixlen = 64 - fls64(diff); 186 if (prefixlen >= limit) 187 return limit; 188 if (diff) 189 return prefixlen; 190 i = 8; 191 } 192 #endif 193 194 while (trie->data_size >= i + 4) { 195 u32 diff = be32_to_cpu(*(__be32 *)&node->data[i] ^ 196 *(__be32 *)&key->data[i]); 197 198 prefixlen += 32 - fls(diff); 199 if (prefixlen >= limit) 200 return limit; 201 if (diff) 202 return prefixlen; 203 i += 4; 204 } 205 206 if (trie->data_size >= i + 2) { 207 u16 diff = be16_to_cpu(*(__be16 *)&node->data[i] ^ 208 *(__be16 *)&key->data[i]); 209 210 prefixlen += 16 - fls(diff); 211 if (prefixlen >= limit) 212 return limit; 213 if (diff) 214 return prefixlen; 215 i += 2; 216 } 217 218 if (trie->data_size >= i + 1) { 219 prefixlen += 8 - fls(node->data[i] ^ key->data[i]); 220 221 if (prefixlen >= limit) 222 return limit; 223 } 224 225 return prefixlen; 226 } 227 228 static size_t longest_prefix_match(const struct lpm_trie *trie, 229 const struct lpm_trie_node *node, 230 const struct bpf_lpm_trie_key_u8 *key) 231 { 232 return __longest_prefix_match(trie, node, key); 233 } 234 235 /* Called from syscall or from eBPF program */ 236 static void *trie_lookup_elem(struct bpf_map *map, void *_key) 237 { 238 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 239 struct lpm_trie_node *node, *found = NULL; 240 struct bpf_lpm_trie_key_u8 *key = _key; 241 242 if (key->prefixlen > trie->max_prefixlen) 243 return NULL; 244 245 /* Start walking the trie from the root node ... */ 246 247 for (node = rcu_dereference_check(trie->root, rcu_read_lock_bh_held()); 248 node;) { 249 unsigned int next_bit; 250 size_t matchlen; 251 252 /* Determine the longest prefix of @node that matches @key. 253 * If it's the maximum possible prefix for this trie, we have 254 * an exact match and can return it directly. 255 */ 256 matchlen = __longest_prefix_match(trie, node, key); 257 if (matchlen == trie->max_prefixlen) { 258 found = node; 259 break; 260 } 261 262 /* If the number of bits that match is smaller than the prefix 263 * length of @node, bail out and return the node we have seen 264 * last in the traversal (ie, the parent). 265 */ 266 if (matchlen < node->prefixlen) 267 break; 268 269 /* Consider this node as return candidate unless it is an 270 * artificially added intermediate one. 271 */ 272 if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) 273 found = node; 274 275 /* If the node match is fully satisfied, let's see if we can 276 * become more specific. Determine the next bit in the key and 277 * traverse down. 278 */ 279 next_bit = extract_bit(key->data, node->prefixlen); 280 node = rcu_dereference_check(node->child[next_bit], 281 rcu_read_lock_bh_held()); 282 } 283 284 if (!found) 285 return NULL; 286 287 return found->data + trie->data_size; 288 } 289 290 static struct lpm_trie_node *lpm_trie_node_alloc(const struct lpm_trie *trie, 291 const void *value) 292 { 293 struct lpm_trie_node *node; 294 size_t size = sizeof(struct lpm_trie_node) + trie->data_size; 295 296 if (value) 297 size += trie->map.value_size; 298 299 node = bpf_map_kmalloc_node(&trie->map, size, GFP_NOWAIT | __GFP_NOWARN, 300 trie->map.numa_node); 301 if (!node) 302 return NULL; 303 304 node->flags = 0; 305 306 if (value) 307 memcpy(node->data + trie->data_size, value, 308 trie->map.value_size); 309 310 return node; 311 } 312 313 /* Called from syscall or from eBPF program */ 314 static long trie_update_elem(struct bpf_map *map, 315 void *_key, void *value, u64 flags) 316 { 317 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 318 struct lpm_trie_node *node, *im_node = NULL, *new_node = NULL; 319 struct lpm_trie_node __rcu **slot; 320 struct bpf_lpm_trie_key_u8 *key = _key; 321 unsigned long irq_flags; 322 unsigned int next_bit; 323 size_t matchlen = 0; 324 int ret = 0; 325 326 if (unlikely(flags > BPF_EXIST)) 327 return -EINVAL; 328 329 if (key->prefixlen > trie->max_prefixlen) 330 return -EINVAL; 331 332 spin_lock_irqsave(&trie->lock, irq_flags); 333 334 /* Allocate and fill a new node */ 335 336 if (trie->n_entries == trie->map.max_entries) { 337 ret = -ENOSPC; 338 goto out; 339 } 340 341 new_node = lpm_trie_node_alloc(trie, value); 342 if (!new_node) { 343 ret = -ENOMEM; 344 goto out; 345 } 346 347 trie->n_entries++; 348 349 new_node->prefixlen = key->prefixlen; 350 RCU_INIT_POINTER(new_node->child[0], NULL); 351 RCU_INIT_POINTER(new_node->child[1], NULL); 352 memcpy(new_node->data, key->data, trie->data_size); 353 354 /* Now find a slot to attach the new node. To do that, walk the tree 355 * from the root and match as many bits as possible for each node until 356 * we either find an empty slot or a slot that needs to be replaced by 357 * an intermediate node. 358 */ 359 slot = &trie->root; 360 361 while ((node = rcu_dereference_protected(*slot, 362 lockdep_is_held(&trie->lock)))) { 363 matchlen = longest_prefix_match(trie, node, key); 364 365 if (node->prefixlen != matchlen || 366 node->prefixlen == key->prefixlen || 367 node->prefixlen == trie->max_prefixlen) 368 break; 369 370 next_bit = extract_bit(key->data, node->prefixlen); 371 slot = &node->child[next_bit]; 372 } 373 374 /* If the slot is empty (a free child pointer or an empty root), 375 * simply assign the @new_node to that slot and be done. 376 */ 377 if (!node) { 378 rcu_assign_pointer(*slot, new_node); 379 goto out; 380 } 381 382 /* If the slot we picked already exists, replace it with @new_node 383 * which already has the correct data array set. 384 */ 385 if (node->prefixlen == matchlen) { 386 new_node->child[0] = node->child[0]; 387 new_node->child[1] = node->child[1]; 388 389 if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) 390 trie->n_entries--; 391 392 rcu_assign_pointer(*slot, new_node); 393 kfree_rcu(node, rcu); 394 395 goto out; 396 } 397 398 /* If the new node matches the prefix completely, it must be inserted 399 * as an ancestor. Simply insert it between @node and *@slot. 400 */ 401 if (matchlen == key->prefixlen) { 402 next_bit = extract_bit(node->data, matchlen); 403 rcu_assign_pointer(new_node->child[next_bit], node); 404 rcu_assign_pointer(*slot, new_node); 405 goto out; 406 } 407 408 im_node = lpm_trie_node_alloc(trie, NULL); 409 if (!im_node) { 410 ret = -ENOMEM; 411 goto out; 412 } 413 414 im_node->prefixlen = matchlen; 415 im_node->flags |= LPM_TREE_NODE_FLAG_IM; 416 memcpy(im_node->data, node->data, trie->data_size); 417 418 /* Now determine which child to install in which slot */ 419 if (extract_bit(key->data, matchlen)) { 420 rcu_assign_pointer(im_node->child[0], node); 421 rcu_assign_pointer(im_node->child[1], new_node); 422 } else { 423 rcu_assign_pointer(im_node->child[0], new_node); 424 rcu_assign_pointer(im_node->child[1], node); 425 } 426 427 /* Finally, assign the intermediate node to the determined slot */ 428 rcu_assign_pointer(*slot, im_node); 429 430 out: 431 if (ret) { 432 if (new_node) 433 trie->n_entries--; 434 435 kfree(new_node); 436 kfree(im_node); 437 } 438 439 spin_unlock_irqrestore(&trie->lock, irq_flags); 440 441 return ret; 442 } 443 444 /* Called from syscall or from eBPF program */ 445 static long trie_delete_elem(struct bpf_map *map, void *_key) 446 { 447 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 448 struct bpf_lpm_trie_key_u8 *key = _key; 449 struct lpm_trie_node __rcu **trim, **trim2; 450 struct lpm_trie_node *node, *parent; 451 unsigned long irq_flags; 452 unsigned int next_bit; 453 size_t matchlen = 0; 454 int ret = 0; 455 456 if (key->prefixlen > trie->max_prefixlen) 457 return -EINVAL; 458 459 spin_lock_irqsave(&trie->lock, irq_flags); 460 461 /* Walk the tree looking for an exact key/length match and keeping 462 * track of the path we traverse. We will need to know the node 463 * we wish to delete, and the slot that points to the node we want 464 * to delete. We may also need to know the nodes parent and the 465 * slot that contains it. 466 */ 467 trim = &trie->root; 468 trim2 = trim; 469 parent = NULL; 470 while ((node = rcu_dereference_protected( 471 *trim, lockdep_is_held(&trie->lock)))) { 472 matchlen = longest_prefix_match(trie, node, key); 473 474 if (node->prefixlen != matchlen || 475 node->prefixlen == key->prefixlen) 476 break; 477 478 parent = node; 479 trim2 = trim; 480 next_bit = extract_bit(key->data, node->prefixlen); 481 trim = &node->child[next_bit]; 482 } 483 484 if (!node || node->prefixlen != key->prefixlen || 485 node->prefixlen != matchlen || 486 (node->flags & LPM_TREE_NODE_FLAG_IM)) { 487 ret = -ENOENT; 488 goto out; 489 } 490 491 trie->n_entries--; 492 493 /* If the node we are removing has two children, simply mark it 494 * as intermediate and we are done. 495 */ 496 if (rcu_access_pointer(node->child[0]) && 497 rcu_access_pointer(node->child[1])) { 498 node->flags |= LPM_TREE_NODE_FLAG_IM; 499 goto out; 500 } 501 502 /* If the parent of the node we are about to delete is an intermediate 503 * node, and the deleted node doesn't have any children, we can delete 504 * the intermediate parent as well and promote its other child 505 * up the tree. Doing this maintains the invariant that all 506 * intermediate nodes have exactly 2 children and that there are no 507 * unnecessary intermediate nodes in the tree. 508 */ 509 if (parent && (parent->flags & LPM_TREE_NODE_FLAG_IM) && 510 !node->child[0] && !node->child[1]) { 511 if (node == rcu_access_pointer(parent->child[0])) 512 rcu_assign_pointer( 513 *trim2, rcu_access_pointer(parent->child[1])); 514 else 515 rcu_assign_pointer( 516 *trim2, rcu_access_pointer(parent->child[0])); 517 kfree_rcu(parent, rcu); 518 kfree_rcu(node, rcu); 519 goto out; 520 } 521 522 /* The node we are removing has either zero or one child. If there 523 * is a child, move it into the removed node's slot then delete 524 * the node. Otherwise just clear the slot and delete the node. 525 */ 526 if (node->child[0]) 527 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[0])); 528 else if (node->child[1]) 529 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[1])); 530 else 531 RCU_INIT_POINTER(*trim, NULL); 532 kfree_rcu(node, rcu); 533 534 out: 535 spin_unlock_irqrestore(&trie->lock, irq_flags); 536 537 return ret; 538 } 539 540 #define LPM_DATA_SIZE_MAX 256 541 #define LPM_DATA_SIZE_MIN 1 542 543 #define LPM_VAL_SIZE_MAX (KMALLOC_MAX_SIZE - LPM_DATA_SIZE_MAX - \ 544 sizeof(struct lpm_trie_node)) 545 #define LPM_VAL_SIZE_MIN 1 546 547 #define LPM_KEY_SIZE(X) (sizeof(struct bpf_lpm_trie_key_u8) + (X)) 548 #define LPM_KEY_SIZE_MAX LPM_KEY_SIZE(LPM_DATA_SIZE_MAX) 549 #define LPM_KEY_SIZE_MIN LPM_KEY_SIZE(LPM_DATA_SIZE_MIN) 550 551 #define LPM_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_NUMA_NODE | \ 552 BPF_F_ACCESS_MASK) 553 554 static struct bpf_map *trie_alloc(union bpf_attr *attr) 555 { 556 struct lpm_trie *trie; 557 558 /* check sanity of attributes */ 559 if (attr->max_entries == 0 || 560 !(attr->map_flags & BPF_F_NO_PREALLOC) || 561 attr->map_flags & ~LPM_CREATE_FLAG_MASK || 562 !bpf_map_flags_access_ok(attr->map_flags) || 563 attr->key_size < LPM_KEY_SIZE_MIN || 564 attr->key_size > LPM_KEY_SIZE_MAX || 565 attr->value_size < LPM_VAL_SIZE_MIN || 566 attr->value_size > LPM_VAL_SIZE_MAX) 567 return ERR_PTR(-EINVAL); 568 569 trie = bpf_map_area_alloc(sizeof(*trie), NUMA_NO_NODE); 570 if (!trie) 571 return ERR_PTR(-ENOMEM); 572 573 /* copy mandatory map attributes */ 574 bpf_map_init_from_attr(&trie->map, attr); 575 trie->data_size = attr->key_size - 576 offsetof(struct bpf_lpm_trie_key_u8, data); 577 trie->max_prefixlen = trie->data_size * 8; 578 579 spin_lock_init(&trie->lock); 580 581 return &trie->map; 582 } 583 584 static void trie_free(struct bpf_map *map) 585 { 586 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 587 struct lpm_trie_node __rcu **slot; 588 struct lpm_trie_node *node; 589 590 /* Always start at the root and walk down to a node that has no 591 * children. Then free that node, nullify its reference in the parent 592 * and start over. 593 */ 594 595 for (;;) { 596 slot = &trie->root; 597 598 for (;;) { 599 node = rcu_dereference_protected(*slot, 1); 600 if (!node) 601 goto out; 602 603 if (rcu_access_pointer(node->child[0])) { 604 slot = &node->child[0]; 605 continue; 606 } 607 608 if (rcu_access_pointer(node->child[1])) { 609 slot = &node->child[1]; 610 continue; 611 } 612 613 kfree(node); 614 RCU_INIT_POINTER(*slot, NULL); 615 break; 616 } 617 } 618 619 out: 620 bpf_map_area_free(trie); 621 } 622 623 static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key) 624 { 625 struct lpm_trie_node *node, *next_node = NULL, *parent, *search_root; 626 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 627 struct bpf_lpm_trie_key_u8 *key = _key, *next_key = _next_key; 628 struct lpm_trie_node **node_stack = NULL; 629 int err = 0, stack_ptr = -1; 630 unsigned int next_bit; 631 size_t matchlen; 632 633 /* The get_next_key follows postorder. For the 4 node example in 634 * the top of this file, the trie_get_next_key() returns the following 635 * one after another: 636 * 192.168.0.0/24 637 * 192.168.1.0/24 638 * 192.168.128.0/24 639 * 192.168.0.0/16 640 * 641 * The idea is to return more specific keys before less specific ones. 642 */ 643 644 /* Empty trie */ 645 search_root = rcu_dereference(trie->root); 646 if (!search_root) 647 return -ENOENT; 648 649 /* For invalid key, find the leftmost node in the trie */ 650 if (!key || key->prefixlen > trie->max_prefixlen) 651 goto find_leftmost; 652 653 node_stack = kmalloc_array(trie->max_prefixlen, 654 sizeof(struct lpm_trie_node *), 655 GFP_ATOMIC | __GFP_NOWARN); 656 if (!node_stack) 657 return -ENOMEM; 658 659 /* Try to find the exact node for the given key */ 660 for (node = search_root; node;) { 661 node_stack[++stack_ptr] = node; 662 matchlen = longest_prefix_match(trie, node, key); 663 if (node->prefixlen != matchlen || 664 node->prefixlen == key->prefixlen) 665 break; 666 667 next_bit = extract_bit(key->data, node->prefixlen); 668 node = rcu_dereference(node->child[next_bit]); 669 } 670 if (!node || node->prefixlen != key->prefixlen || 671 (node->flags & LPM_TREE_NODE_FLAG_IM)) 672 goto find_leftmost; 673 674 /* The node with the exactly-matching key has been found, 675 * find the first node in postorder after the matched node. 676 */ 677 node = node_stack[stack_ptr]; 678 while (stack_ptr > 0) { 679 parent = node_stack[stack_ptr - 1]; 680 if (rcu_dereference(parent->child[0]) == node) { 681 search_root = rcu_dereference(parent->child[1]); 682 if (search_root) 683 goto find_leftmost; 684 } 685 if (!(parent->flags & LPM_TREE_NODE_FLAG_IM)) { 686 next_node = parent; 687 goto do_copy; 688 } 689 690 node = parent; 691 stack_ptr--; 692 } 693 694 /* did not find anything */ 695 err = -ENOENT; 696 goto free_stack; 697 698 find_leftmost: 699 /* Find the leftmost non-intermediate node, all intermediate nodes 700 * have exact two children, so this function will never return NULL. 701 */ 702 for (node = search_root; node;) { 703 if (node->flags & LPM_TREE_NODE_FLAG_IM) { 704 node = rcu_dereference(node->child[0]); 705 } else { 706 next_node = node; 707 node = rcu_dereference(node->child[0]); 708 if (!node) 709 node = rcu_dereference(next_node->child[1]); 710 } 711 } 712 do_copy: 713 next_key->prefixlen = next_node->prefixlen; 714 memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key_u8, data), 715 next_node->data, trie->data_size); 716 free_stack: 717 kfree(node_stack); 718 return err; 719 } 720 721 static int trie_check_btf(const struct bpf_map *map, 722 const struct btf *btf, 723 const struct btf_type *key_type, 724 const struct btf_type *value_type) 725 { 726 /* Keys must have struct bpf_lpm_trie_key_u8 embedded. */ 727 return BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ? 728 -EINVAL : 0; 729 } 730 731 static u64 trie_mem_usage(const struct bpf_map *map) 732 { 733 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 734 u64 elem_size; 735 736 elem_size = sizeof(struct lpm_trie_node) + trie->data_size + 737 trie->map.value_size; 738 return elem_size * READ_ONCE(trie->n_entries); 739 } 740 741 BTF_ID_LIST_SINGLE(trie_map_btf_ids, struct, lpm_trie) 742 const struct bpf_map_ops trie_map_ops = { 743 .map_meta_equal = bpf_map_meta_equal, 744 .map_alloc = trie_alloc, 745 .map_free = trie_free, 746 .map_get_next_key = trie_get_next_key, 747 .map_lookup_elem = trie_lookup_elem, 748 .map_update_elem = trie_update_elem, 749 .map_delete_elem = trie_delete_elem, 750 .map_lookup_batch = generic_map_lookup_batch, 751 .map_update_batch = generic_map_update_batch, 752 .map_delete_batch = generic_map_delete_batch, 753 .map_check_btf = trie_check_btf, 754 .map_mem_usage = trie_mem_usage, 755 .map_btf_id = &trie_map_btf_ids[0], 756 }; 757