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 #include <linux/bpf_mem_alloc.h> 19 20 /* Intermediate node */ 21 #define LPM_TREE_NODE_FLAG_IM BIT(0) 22 23 struct lpm_trie_node; 24 25 struct lpm_trie_node { 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 struct bpf_mem_alloc ma; 36 size_t n_entries; 37 size_t max_prefixlen; 38 size_t data_size; 39 raw_spinlock_t lock; 40 }; 41 42 /* This trie implements a longest prefix match algorithm that can be used to 43 * match IP addresses to a stored set of ranges. 44 * 45 * Data stored in @data of struct bpf_lpm_key and struct lpm_trie_node is 46 * interpreted as big endian, so data[0] stores the most significant byte. 47 * 48 * Match ranges are internally stored in instances of struct lpm_trie_node 49 * which each contain their prefix length as well as two pointers that may 50 * lead to more nodes containing more specific matches. Each node also stores 51 * a value that is defined by and returned to userspace via the update_elem 52 * and lookup functions. 53 * 54 * For instance, let's start with a trie that was created with a prefix length 55 * of 32, so it can be used for IPv4 addresses, and one single element that 56 * matches 192.168.0.0/16. The data array would hence contain 57 * [0xc0, 0xa8, 0x00, 0x00] in big-endian notation. This documentation will 58 * stick to IP-address notation for readability though. 59 * 60 * As the trie is empty initially, the new node (1) will be places as root 61 * node, denoted as (R) in the example below. As there are no other node, both 62 * child pointers are %NULL. 63 * 64 * +----------------+ 65 * | (1) (R) | 66 * | 192.168.0.0/16 | 67 * | value: 1 | 68 * | [0] [1] | 69 * +----------------+ 70 * 71 * Next, let's add a new node (2) matching 192.168.0.0/24. As there is already 72 * a node with the same data and a smaller prefix (ie, a less specific one), 73 * node (2) will become a child of (1). In child index depends on the next bit 74 * that is outside of what (1) matches, and that bit is 0, so (2) will be 75 * child[0] of (1): 76 * 77 * +----------------+ 78 * | (1) (R) | 79 * | 192.168.0.0/16 | 80 * | value: 1 | 81 * | [0] [1] | 82 * +----------------+ 83 * | 84 * +----------------+ 85 * | (2) | 86 * | 192.168.0.0/24 | 87 * | value: 2 | 88 * | [0] [1] | 89 * +----------------+ 90 * 91 * The child[1] slot of (1) could be filled with another node which has bit #17 92 * (the next bit after the ones that (1) matches on) set to 1. For instance, 93 * 192.168.128.0/24: 94 * 95 * +----------------+ 96 * | (1) (R) | 97 * | 192.168.0.0/16 | 98 * | value: 1 | 99 * | [0] [1] | 100 * +----------------+ 101 * | | 102 * +----------------+ +------------------+ 103 * | (2) | | (3) | 104 * | 192.168.0.0/24 | | 192.168.128.0/24 | 105 * | value: 2 | | value: 3 | 106 * | [0] [1] | | [0] [1] | 107 * +----------------+ +------------------+ 108 * 109 * Let's add another node (4) to the game for 192.168.1.0/24. In order to place 110 * it, node (1) is looked at first, and because (4) of the semantics laid out 111 * above (bit #17 is 0), it would normally be attached to (1) as child[0]. 112 * However, that slot is already allocated, so a new node is needed in between. 113 * That node does not have a value attached to it and it will never be 114 * returned to users as result of a lookup. It is only there to differentiate 115 * the traversal further. It will get a prefix as wide as necessary to 116 * distinguish its two children: 117 * 118 * +----------------+ 119 * | (1) (R) | 120 * | 192.168.0.0/16 | 121 * | value: 1 | 122 * | [0] [1] | 123 * +----------------+ 124 * | | 125 * +----------------+ +------------------+ 126 * | (4) (I) | | (3) | 127 * | 192.168.0.0/23 | | 192.168.128.0/24 | 128 * | value: --- | | value: 3 | 129 * | [0] [1] | | [0] [1] | 130 * +----------------+ +------------------+ 131 * | | 132 * +----------------+ +----------------+ 133 * | (2) | | (5) | 134 * | 192.168.0.0/24 | | 192.168.1.0/24 | 135 * | value: 2 | | value: 5 | 136 * | [0] [1] | | [0] [1] | 137 * +----------------+ +----------------+ 138 * 139 * 192.168.1.1/32 would be a child of (5) etc. 140 * 141 * An intermediate node will be turned into a 'real' node on demand. In the 142 * example above, (4) would be re-used if 192.168.0.0/23 is added to the trie. 143 * 144 * A fully populated trie would have a height of 32 nodes, as the trie was 145 * created with a prefix length of 32. 146 * 147 * The lookup starts at the root node. If the current node matches and if there 148 * is a child that can be used to become more specific, the trie is traversed 149 * downwards. The last node in the traversal that is a non-intermediate one is 150 * returned. 151 */ 152 153 static inline int extract_bit(const u8 *data, size_t index) 154 { 155 return !!(data[index / 8] & (1 << (7 - (index % 8)))); 156 } 157 158 /** 159 * __longest_prefix_match() - determine the longest prefix 160 * @trie: The trie to get internal sizes from 161 * @node: The node to operate on 162 * @key: The key to compare to @node 163 * 164 * Determine the longest prefix of @node that matches the bits in @key. 165 */ 166 static __always_inline 167 size_t __longest_prefix_match(const struct lpm_trie *trie, 168 const struct lpm_trie_node *node, 169 const struct bpf_lpm_trie_key_u8 *key) 170 { 171 u32 limit = min(node->prefixlen, key->prefixlen); 172 u32 prefixlen = 0, i = 0; 173 174 BUILD_BUG_ON(offsetof(struct lpm_trie_node, data) % sizeof(u32)); 175 BUILD_BUG_ON(offsetof(struct bpf_lpm_trie_key_u8, data) % sizeof(u32)); 176 177 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && defined(CONFIG_64BIT) 178 179 /* data_size >= 16 has very small probability. 180 * We do not use a loop for optimal code generation. 181 */ 182 if (trie->data_size >= 8) { 183 u64 diff = be64_to_cpu(*(__be64 *)node->data ^ 184 *(__be64 *)key->data); 185 186 prefixlen = 64 - fls64(diff); 187 if (prefixlen >= limit) 188 return limit; 189 if (diff) 190 return prefixlen; 191 i = 8; 192 } 193 #endif 194 195 while (trie->data_size >= i + 4) { 196 u32 diff = be32_to_cpu(*(__be32 *)&node->data[i] ^ 197 *(__be32 *)&key->data[i]); 198 199 prefixlen += 32 - fls(diff); 200 if (prefixlen >= limit) 201 return limit; 202 if (diff) 203 return prefixlen; 204 i += 4; 205 } 206 207 if (trie->data_size >= i + 2) { 208 u16 diff = be16_to_cpu(*(__be16 *)&node->data[i] ^ 209 *(__be16 *)&key->data[i]); 210 211 prefixlen += 16 - fls(diff); 212 if (prefixlen >= limit) 213 return limit; 214 if (diff) 215 return prefixlen; 216 i += 2; 217 } 218 219 if (trie->data_size >= i + 1) { 220 prefixlen += 8 - fls(node->data[i] ^ key->data[i]); 221 222 if (prefixlen >= limit) 223 return limit; 224 } 225 226 return prefixlen; 227 } 228 229 static size_t longest_prefix_match(const struct lpm_trie *trie, 230 const struct lpm_trie_node *node, 231 const struct bpf_lpm_trie_key_u8 *key) 232 { 233 return __longest_prefix_match(trie, node, key); 234 } 235 236 /* Called from syscall or from eBPF program */ 237 static void *trie_lookup_elem(struct bpf_map *map, void *_key) 238 { 239 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 240 struct lpm_trie_node *node, *found = NULL; 241 struct bpf_lpm_trie_key_u8 *key = _key; 242 243 if (key->prefixlen > trie->max_prefixlen) 244 return NULL; 245 246 /* Start walking the trie from the root node ... */ 247 248 for (node = rcu_dereference_check(trie->root, rcu_read_lock_bh_held()); 249 node;) { 250 unsigned int next_bit; 251 size_t matchlen; 252 253 /* Determine the longest prefix of @node that matches @key. 254 * If it's the maximum possible prefix for this trie, we have 255 * an exact match and can return it directly. 256 */ 257 matchlen = __longest_prefix_match(trie, node, key); 258 if (matchlen == trie->max_prefixlen) { 259 found = node; 260 break; 261 } 262 263 /* If the number of bits that match is smaller than the prefix 264 * length of @node, bail out and return the node we have seen 265 * last in the traversal (ie, the parent). 266 */ 267 if (matchlen < node->prefixlen) 268 break; 269 270 /* Consider this node as return candidate unless it is an 271 * artificially added intermediate one. 272 */ 273 if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) 274 found = node; 275 276 /* If the node match is fully satisfied, let's see if we can 277 * become more specific. Determine the next bit in the key and 278 * traverse down. 279 */ 280 next_bit = extract_bit(key->data, node->prefixlen); 281 node = rcu_dereference_check(node->child[next_bit], 282 rcu_read_lock_bh_held()); 283 } 284 285 if (!found) 286 return NULL; 287 288 return found->data + trie->data_size; 289 } 290 291 static struct lpm_trie_node *lpm_trie_node_alloc(struct lpm_trie *trie, 292 const void *value) 293 { 294 struct lpm_trie_node *node; 295 296 node = bpf_mem_cache_alloc(&trie->ma); 297 298 if (!node) 299 return NULL; 300 301 node->flags = 0; 302 303 if (value) 304 memcpy(node->data + trie->data_size, value, 305 trie->map.value_size); 306 307 return node; 308 } 309 310 static int trie_check_add_elem(struct lpm_trie *trie, u64 flags) 311 { 312 if (flags == BPF_EXIST) 313 return -ENOENT; 314 if (trie->n_entries == trie->map.max_entries) 315 return -ENOSPC; 316 trie->n_entries++; 317 return 0; 318 } 319 320 /* Called from syscall or from eBPF program */ 321 static long trie_update_elem(struct bpf_map *map, 322 void *_key, void *value, u64 flags) 323 { 324 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 325 struct lpm_trie_node *node, *im_node, *new_node; 326 struct lpm_trie_node *free_node = NULL; 327 struct lpm_trie_node __rcu **slot; 328 struct bpf_lpm_trie_key_u8 *key = _key; 329 unsigned long irq_flags; 330 unsigned int next_bit; 331 size_t matchlen = 0; 332 int ret = 0; 333 334 if (unlikely(flags > BPF_EXIST)) 335 return -EINVAL; 336 337 if (key->prefixlen > trie->max_prefixlen) 338 return -EINVAL; 339 340 /* Allocate and fill a new node */ 341 new_node = lpm_trie_node_alloc(trie, value); 342 if (!new_node) 343 return -ENOMEM; 344 345 raw_spin_lock_irqsave(&trie->lock, irq_flags); 346 347 new_node->prefixlen = key->prefixlen; 348 RCU_INIT_POINTER(new_node->child[0], NULL); 349 RCU_INIT_POINTER(new_node->child[1], NULL); 350 memcpy(new_node->data, key->data, trie->data_size); 351 352 /* Now find a slot to attach the new node. To do that, walk the tree 353 * from the root and match as many bits as possible for each node until 354 * we either find an empty slot or a slot that needs to be replaced by 355 * an intermediate node. 356 */ 357 slot = &trie->root; 358 359 while ((node = rcu_dereference_protected(*slot, 360 lockdep_is_held(&trie->lock)))) { 361 matchlen = longest_prefix_match(trie, node, key); 362 363 if (node->prefixlen != matchlen || 364 node->prefixlen == key->prefixlen) 365 break; 366 367 next_bit = extract_bit(key->data, node->prefixlen); 368 slot = &node->child[next_bit]; 369 } 370 371 /* If the slot is empty (a free child pointer or an empty root), 372 * simply assign the @new_node to that slot and be done. 373 */ 374 if (!node) { 375 ret = trie_check_add_elem(trie, flags); 376 if (ret) 377 goto out; 378 379 rcu_assign_pointer(*slot, new_node); 380 goto out; 381 } 382 383 /* If the slot we picked already exists, replace it with @new_node 384 * which already has the correct data array set. 385 */ 386 if (node->prefixlen == matchlen) { 387 if (!(node->flags & LPM_TREE_NODE_FLAG_IM)) { 388 if (flags == BPF_NOEXIST) { 389 ret = -EEXIST; 390 goto out; 391 } 392 } else { 393 ret = trie_check_add_elem(trie, flags); 394 if (ret) 395 goto out; 396 } 397 398 new_node->child[0] = node->child[0]; 399 new_node->child[1] = node->child[1]; 400 401 rcu_assign_pointer(*slot, new_node); 402 free_node = node; 403 404 goto out; 405 } 406 407 ret = trie_check_add_elem(trie, flags); 408 if (ret) 409 goto out; 410 411 /* If the new node matches the prefix completely, it must be inserted 412 * as an ancestor. Simply insert it between @node and *@slot. 413 */ 414 if (matchlen == key->prefixlen) { 415 next_bit = extract_bit(node->data, matchlen); 416 rcu_assign_pointer(new_node->child[next_bit], node); 417 rcu_assign_pointer(*slot, new_node); 418 goto out; 419 } 420 421 im_node = lpm_trie_node_alloc(trie, NULL); 422 if (!im_node) { 423 trie->n_entries--; 424 ret = -ENOMEM; 425 goto out; 426 } 427 428 im_node->prefixlen = matchlen; 429 im_node->flags |= LPM_TREE_NODE_FLAG_IM; 430 memcpy(im_node->data, node->data, trie->data_size); 431 432 /* Now determine which child to install in which slot */ 433 if (extract_bit(key->data, matchlen)) { 434 rcu_assign_pointer(im_node->child[0], node); 435 rcu_assign_pointer(im_node->child[1], new_node); 436 } else { 437 rcu_assign_pointer(im_node->child[0], new_node); 438 rcu_assign_pointer(im_node->child[1], node); 439 } 440 441 /* Finally, assign the intermediate node to the determined slot */ 442 rcu_assign_pointer(*slot, im_node); 443 444 out: 445 raw_spin_unlock_irqrestore(&trie->lock, irq_flags); 446 447 if (ret) 448 bpf_mem_cache_free(&trie->ma, new_node); 449 bpf_mem_cache_free_rcu(&trie->ma, free_node); 450 451 return ret; 452 } 453 454 /* Called from syscall or from eBPF program */ 455 static long trie_delete_elem(struct bpf_map *map, void *_key) 456 { 457 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 458 struct lpm_trie_node *free_node = NULL, *free_parent = NULL; 459 struct bpf_lpm_trie_key_u8 *key = _key; 460 struct lpm_trie_node __rcu **trim, **trim2; 461 struct lpm_trie_node *node, *parent; 462 unsigned long irq_flags; 463 unsigned int next_bit; 464 size_t matchlen = 0; 465 int ret = 0; 466 467 if (key->prefixlen > trie->max_prefixlen) 468 return -EINVAL; 469 470 raw_spin_lock_irqsave(&trie->lock, irq_flags); 471 472 /* Walk the tree looking for an exact key/length match and keeping 473 * track of the path we traverse. We will need to know the node 474 * we wish to delete, and the slot that points to the node we want 475 * to delete. We may also need to know the nodes parent and the 476 * slot that contains it. 477 */ 478 trim = &trie->root; 479 trim2 = trim; 480 parent = NULL; 481 while ((node = rcu_dereference_protected( 482 *trim, lockdep_is_held(&trie->lock)))) { 483 matchlen = longest_prefix_match(trie, node, key); 484 485 if (node->prefixlen != matchlen || 486 node->prefixlen == key->prefixlen) 487 break; 488 489 parent = node; 490 trim2 = trim; 491 next_bit = extract_bit(key->data, node->prefixlen); 492 trim = &node->child[next_bit]; 493 } 494 495 if (!node || node->prefixlen != key->prefixlen || 496 node->prefixlen != matchlen || 497 (node->flags & LPM_TREE_NODE_FLAG_IM)) { 498 ret = -ENOENT; 499 goto out; 500 } 501 502 trie->n_entries--; 503 504 /* If the node we are removing has two children, simply mark it 505 * as intermediate and we are done. 506 */ 507 if (rcu_access_pointer(node->child[0]) && 508 rcu_access_pointer(node->child[1])) { 509 node->flags |= LPM_TREE_NODE_FLAG_IM; 510 goto out; 511 } 512 513 /* If the parent of the node we are about to delete is an intermediate 514 * node, and the deleted node doesn't have any children, we can delete 515 * the intermediate parent as well and promote its other child 516 * up the tree. Doing this maintains the invariant that all 517 * intermediate nodes have exactly 2 children and that there are no 518 * unnecessary intermediate nodes in the tree. 519 */ 520 if (parent && (parent->flags & LPM_TREE_NODE_FLAG_IM) && 521 !node->child[0] && !node->child[1]) { 522 if (node == rcu_access_pointer(parent->child[0])) 523 rcu_assign_pointer( 524 *trim2, rcu_access_pointer(parent->child[1])); 525 else 526 rcu_assign_pointer( 527 *trim2, rcu_access_pointer(parent->child[0])); 528 free_parent = parent; 529 free_node = node; 530 goto out; 531 } 532 533 /* The node we are removing has either zero or one child. If there 534 * is a child, move it into the removed node's slot then delete 535 * the node. Otherwise just clear the slot and delete the node. 536 */ 537 if (node->child[0]) 538 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[0])); 539 else if (node->child[1]) 540 rcu_assign_pointer(*trim, rcu_access_pointer(node->child[1])); 541 else 542 RCU_INIT_POINTER(*trim, NULL); 543 free_node = node; 544 545 out: 546 raw_spin_unlock_irqrestore(&trie->lock, irq_flags); 547 548 bpf_mem_cache_free_rcu(&trie->ma, free_parent); 549 bpf_mem_cache_free_rcu(&trie->ma, free_node); 550 551 return ret; 552 } 553 554 #define LPM_DATA_SIZE_MAX 256 555 #define LPM_DATA_SIZE_MIN 1 556 557 #define LPM_VAL_SIZE_MAX (KMALLOC_MAX_SIZE - LPM_DATA_SIZE_MAX - \ 558 sizeof(struct lpm_trie_node)) 559 #define LPM_VAL_SIZE_MIN 1 560 561 #define LPM_KEY_SIZE(X) (sizeof(struct bpf_lpm_trie_key_u8) + (X)) 562 #define LPM_KEY_SIZE_MAX LPM_KEY_SIZE(LPM_DATA_SIZE_MAX) 563 #define LPM_KEY_SIZE_MIN LPM_KEY_SIZE(LPM_DATA_SIZE_MIN) 564 565 #define LPM_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_NUMA_NODE | \ 566 BPF_F_ACCESS_MASK) 567 568 static struct bpf_map *trie_alloc(union bpf_attr *attr) 569 { 570 struct lpm_trie *trie; 571 size_t leaf_size; 572 int err; 573 574 /* check sanity of attributes */ 575 if (attr->max_entries == 0 || 576 !(attr->map_flags & BPF_F_NO_PREALLOC) || 577 attr->map_flags & ~LPM_CREATE_FLAG_MASK || 578 !bpf_map_flags_access_ok(attr->map_flags) || 579 attr->key_size < LPM_KEY_SIZE_MIN || 580 attr->key_size > LPM_KEY_SIZE_MAX || 581 attr->value_size < LPM_VAL_SIZE_MIN || 582 attr->value_size > LPM_VAL_SIZE_MAX) 583 return ERR_PTR(-EINVAL); 584 585 trie = bpf_map_area_alloc(sizeof(*trie), NUMA_NO_NODE); 586 if (!trie) 587 return ERR_PTR(-ENOMEM); 588 589 /* copy mandatory map attributes */ 590 bpf_map_init_from_attr(&trie->map, attr); 591 trie->data_size = attr->key_size - 592 offsetof(struct bpf_lpm_trie_key_u8, data); 593 trie->max_prefixlen = trie->data_size * 8; 594 595 raw_spin_lock_init(&trie->lock); 596 597 /* Allocate intermediate and leaf nodes from the same allocator */ 598 leaf_size = sizeof(struct lpm_trie_node) + trie->data_size + 599 trie->map.value_size; 600 err = bpf_mem_alloc_init(&trie->ma, leaf_size, false); 601 if (err) 602 goto free_out; 603 return &trie->map; 604 605 free_out: 606 bpf_map_area_free(trie); 607 return ERR_PTR(err); 608 } 609 610 static void trie_free(struct bpf_map *map) 611 { 612 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 613 struct lpm_trie_node __rcu **slot; 614 struct lpm_trie_node *node; 615 616 /* Always start at the root and walk down to a node that has no 617 * children. Then free that node, nullify its reference in the parent 618 * and start over. 619 */ 620 621 for (;;) { 622 slot = &trie->root; 623 624 for (;;) { 625 node = rcu_dereference_protected(*slot, 1); 626 if (!node) 627 goto out; 628 629 if (rcu_access_pointer(node->child[0])) { 630 slot = &node->child[0]; 631 continue; 632 } 633 634 if (rcu_access_pointer(node->child[1])) { 635 slot = &node->child[1]; 636 continue; 637 } 638 639 /* No bpf program may access the map, so freeing the 640 * node without waiting for the extra RCU GP. 641 */ 642 bpf_mem_cache_raw_free(node); 643 RCU_INIT_POINTER(*slot, NULL); 644 break; 645 } 646 } 647 648 out: 649 bpf_mem_alloc_destroy(&trie->ma); 650 bpf_map_area_free(trie); 651 } 652 653 static int trie_get_next_key(struct bpf_map *map, void *_key, void *_next_key) 654 { 655 struct lpm_trie_node *node, *next_node = NULL, *parent, *search_root; 656 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 657 struct bpf_lpm_trie_key_u8 *key = _key, *next_key = _next_key; 658 struct lpm_trie_node **node_stack = NULL; 659 int err = 0, stack_ptr = -1; 660 unsigned int next_bit; 661 size_t matchlen = 0; 662 663 /* The get_next_key follows postorder. For the 4 node example in 664 * the top of this file, the trie_get_next_key() returns the following 665 * one after another: 666 * 192.168.0.0/24 667 * 192.168.1.0/24 668 * 192.168.128.0/24 669 * 192.168.0.0/16 670 * 671 * The idea is to return more specific keys before less specific ones. 672 */ 673 674 /* Empty trie */ 675 search_root = rcu_dereference(trie->root); 676 if (!search_root) 677 return -ENOENT; 678 679 /* For invalid key, find the leftmost node in the trie */ 680 if (!key || key->prefixlen > trie->max_prefixlen) 681 goto find_leftmost; 682 683 node_stack = kmalloc_array(trie->max_prefixlen + 1, 684 sizeof(struct lpm_trie_node *), 685 GFP_ATOMIC | __GFP_NOWARN); 686 if (!node_stack) 687 return -ENOMEM; 688 689 /* Try to find the exact node for the given key */ 690 for (node = search_root; node;) { 691 node_stack[++stack_ptr] = node; 692 matchlen = longest_prefix_match(trie, node, key); 693 if (node->prefixlen != matchlen || 694 node->prefixlen == key->prefixlen) 695 break; 696 697 next_bit = extract_bit(key->data, node->prefixlen); 698 node = rcu_dereference(node->child[next_bit]); 699 } 700 if (!node || node->prefixlen != matchlen || 701 (node->flags & LPM_TREE_NODE_FLAG_IM)) 702 goto find_leftmost; 703 704 /* The node with the exactly-matching key has been found, 705 * find the first node in postorder after the matched node. 706 */ 707 node = node_stack[stack_ptr]; 708 while (stack_ptr > 0) { 709 parent = node_stack[stack_ptr - 1]; 710 if (rcu_dereference(parent->child[0]) == node) { 711 search_root = rcu_dereference(parent->child[1]); 712 if (search_root) 713 goto find_leftmost; 714 } 715 if (!(parent->flags & LPM_TREE_NODE_FLAG_IM)) { 716 next_node = parent; 717 goto do_copy; 718 } 719 720 node = parent; 721 stack_ptr--; 722 } 723 724 /* did not find anything */ 725 err = -ENOENT; 726 goto free_stack; 727 728 find_leftmost: 729 /* Find the leftmost non-intermediate node, all intermediate nodes 730 * have exact two children, so this function will never return NULL. 731 */ 732 for (node = search_root; node;) { 733 if (node->flags & LPM_TREE_NODE_FLAG_IM) { 734 node = rcu_dereference(node->child[0]); 735 } else { 736 next_node = node; 737 node = rcu_dereference(node->child[0]); 738 if (!node) 739 node = rcu_dereference(next_node->child[1]); 740 } 741 } 742 do_copy: 743 next_key->prefixlen = next_node->prefixlen; 744 memcpy((void *)next_key + offsetof(struct bpf_lpm_trie_key_u8, data), 745 next_node->data, trie->data_size); 746 free_stack: 747 kfree(node_stack); 748 return err; 749 } 750 751 static int trie_check_btf(const struct bpf_map *map, 752 const struct btf *btf, 753 const struct btf_type *key_type, 754 const struct btf_type *value_type) 755 { 756 /* Keys must have struct bpf_lpm_trie_key_u8 embedded. */ 757 return BTF_INFO_KIND(key_type->info) != BTF_KIND_STRUCT ? 758 -EINVAL : 0; 759 } 760 761 static u64 trie_mem_usage(const struct bpf_map *map) 762 { 763 struct lpm_trie *trie = container_of(map, struct lpm_trie, map); 764 u64 elem_size; 765 766 elem_size = sizeof(struct lpm_trie_node) + trie->data_size + 767 trie->map.value_size; 768 return elem_size * READ_ONCE(trie->n_entries); 769 } 770 771 BTF_ID_LIST_SINGLE(trie_map_btf_ids, struct, lpm_trie) 772 const struct bpf_map_ops trie_map_ops = { 773 .map_meta_equal = bpf_map_meta_equal, 774 .map_alloc = trie_alloc, 775 .map_free = trie_free, 776 .map_get_next_key = trie_get_next_key, 777 .map_lookup_elem = trie_lookup_elem, 778 .map_update_elem = trie_update_elem, 779 .map_delete_elem = trie_delete_elem, 780 .map_lookup_batch = generic_map_lookup_batch, 781 .map_update_batch = generic_map_update_batch, 782 .map_delete_batch = generic_map_delete_batch, 783 .map_check_btf = trie_check_btf, 784 .map_mem_usage = trie_mem_usage, 785 .map_btf_id = &trie_map_btf_ids[0], 786 }; 787