1 /* Keyring handling 2 * 3 * Copyright (C) 2004-2005, 2008, 2013 Red Hat, Inc. All Rights Reserved. 4 * Written by David Howells (dhowells@redhat.com) 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 #include <linux/export.h> 13 #include <linux/init.h> 14 #include <linux/sched.h> 15 #include <linux/slab.h> 16 #include <linux/security.h> 17 #include <linux/seq_file.h> 18 #include <linux/err.h> 19 #include <keys/keyring-type.h> 20 #include <keys/user-type.h> 21 #include <linux/assoc_array_priv.h> 22 #include <linux/uaccess.h> 23 #include "internal.h" 24 25 /* 26 * When plumbing the depths of the key tree, this sets a hard limit 27 * set on how deep we're willing to go. 28 */ 29 #define KEYRING_SEARCH_MAX_DEPTH 6 30 31 /* 32 * We keep all named keyrings in a hash to speed looking them up. 33 */ 34 #define KEYRING_NAME_HASH_SIZE (1 << 5) 35 36 /* 37 * We mark pointers we pass to the associative array with bit 1 set if 38 * they're keyrings and clear otherwise. 39 */ 40 #define KEYRING_PTR_SUBTYPE 0x2UL 41 42 static inline bool keyring_ptr_is_keyring(const struct assoc_array_ptr *x) 43 { 44 return (unsigned long)x & KEYRING_PTR_SUBTYPE; 45 } 46 static inline struct key *keyring_ptr_to_key(const struct assoc_array_ptr *x) 47 { 48 void *object = assoc_array_ptr_to_leaf(x); 49 return (struct key *)((unsigned long)object & ~KEYRING_PTR_SUBTYPE); 50 } 51 static inline void *keyring_key_to_ptr(struct key *key) 52 { 53 if (key->type == &key_type_keyring) 54 return (void *)((unsigned long)key | KEYRING_PTR_SUBTYPE); 55 return key; 56 } 57 58 static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE]; 59 static DEFINE_RWLOCK(keyring_name_lock); 60 61 static inline unsigned keyring_hash(const char *desc) 62 { 63 unsigned bucket = 0; 64 65 for (; *desc; desc++) 66 bucket += (unsigned char)*desc; 67 68 return bucket & (KEYRING_NAME_HASH_SIZE - 1); 69 } 70 71 /* 72 * The keyring key type definition. Keyrings are simply keys of this type and 73 * can be treated as ordinary keys in addition to having their own special 74 * operations. 75 */ 76 static int keyring_preparse(struct key_preparsed_payload *prep); 77 static void keyring_free_preparse(struct key_preparsed_payload *prep); 78 static int keyring_instantiate(struct key *keyring, 79 struct key_preparsed_payload *prep); 80 static void keyring_revoke(struct key *keyring); 81 static void keyring_destroy(struct key *keyring); 82 static void keyring_describe(const struct key *keyring, struct seq_file *m); 83 static long keyring_read(const struct key *keyring, 84 char __user *buffer, size_t buflen); 85 86 struct key_type key_type_keyring = { 87 .name = "keyring", 88 .def_datalen = 0, 89 .preparse = keyring_preparse, 90 .free_preparse = keyring_free_preparse, 91 .instantiate = keyring_instantiate, 92 .revoke = keyring_revoke, 93 .destroy = keyring_destroy, 94 .describe = keyring_describe, 95 .read = keyring_read, 96 }; 97 EXPORT_SYMBOL(key_type_keyring); 98 99 /* 100 * Semaphore to serialise link/link calls to prevent two link calls in parallel 101 * introducing a cycle. 102 */ 103 static DECLARE_RWSEM(keyring_serialise_link_sem); 104 105 /* 106 * Publish the name of a keyring so that it can be found by name (if it has 107 * one). 108 */ 109 static void keyring_publish_name(struct key *keyring) 110 { 111 int bucket; 112 113 if (keyring->description) { 114 bucket = keyring_hash(keyring->description); 115 116 write_lock(&keyring_name_lock); 117 118 if (!keyring_name_hash[bucket].next) 119 INIT_LIST_HEAD(&keyring_name_hash[bucket]); 120 121 list_add_tail(&keyring->name_link, 122 &keyring_name_hash[bucket]); 123 124 write_unlock(&keyring_name_lock); 125 } 126 } 127 128 /* 129 * Preparse a keyring payload 130 */ 131 static int keyring_preparse(struct key_preparsed_payload *prep) 132 { 133 return prep->datalen != 0 ? -EINVAL : 0; 134 } 135 136 /* 137 * Free a preparse of a user defined key payload 138 */ 139 static void keyring_free_preparse(struct key_preparsed_payload *prep) 140 { 141 } 142 143 /* 144 * Initialise a keyring. 145 * 146 * Returns 0 on success, -EINVAL if given any data. 147 */ 148 static int keyring_instantiate(struct key *keyring, 149 struct key_preparsed_payload *prep) 150 { 151 assoc_array_init(&keyring->keys); 152 /* make the keyring available by name if it has one */ 153 keyring_publish_name(keyring); 154 return 0; 155 } 156 157 /* 158 * Multiply 64-bits by 32-bits to 96-bits and fold back to 64-bit. Ideally we'd 159 * fold the carry back too, but that requires inline asm. 160 */ 161 static u64 mult_64x32_and_fold(u64 x, u32 y) 162 { 163 u64 hi = (u64)(u32)(x >> 32) * y; 164 u64 lo = (u64)(u32)(x) * y; 165 return lo + ((u64)(u32)hi << 32) + (u32)(hi >> 32); 166 } 167 168 /* 169 * Hash a key type and description. 170 */ 171 static unsigned long hash_key_type_and_desc(const struct keyring_index_key *index_key) 172 { 173 const unsigned level_shift = ASSOC_ARRAY_LEVEL_STEP; 174 const unsigned long fan_mask = ASSOC_ARRAY_FAN_MASK; 175 const char *description = index_key->description; 176 unsigned long hash, type; 177 u32 piece; 178 u64 acc; 179 int n, desc_len = index_key->desc_len; 180 181 type = (unsigned long)index_key->type; 182 183 acc = mult_64x32_and_fold(type, desc_len + 13); 184 acc = mult_64x32_and_fold(acc, 9207); 185 for (;;) { 186 n = desc_len; 187 if (n <= 0) 188 break; 189 if (n > 4) 190 n = 4; 191 piece = 0; 192 memcpy(&piece, description, n); 193 description += n; 194 desc_len -= n; 195 acc = mult_64x32_and_fold(acc, piece); 196 acc = mult_64x32_and_fold(acc, 9207); 197 } 198 199 /* Fold the hash down to 32 bits if need be. */ 200 hash = acc; 201 if (ASSOC_ARRAY_KEY_CHUNK_SIZE == 32) 202 hash ^= acc >> 32; 203 204 /* Squidge all the keyrings into a separate part of the tree to 205 * ordinary keys by making sure the lowest level segment in the hash is 206 * zero for keyrings and non-zero otherwise. 207 */ 208 if (index_key->type != &key_type_keyring && (hash & fan_mask) == 0) 209 return hash | (hash >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - level_shift)) | 1; 210 if (index_key->type == &key_type_keyring && (hash & fan_mask) != 0) 211 return (hash + (hash << level_shift)) & ~fan_mask; 212 return hash; 213 } 214 215 /* 216 * Build the next index key chunk. 217 * 218 * On 32-bit systems the index key is laid out as: 219 * 220 * 0 4 5 9... 221 * hash desclen typeptr desc[] 222 * 223 * On 64-bit systems: 224 * 225 * 0 8 9 17... 226 * hash desclen typeptr desc[] 227 * 228 * We return it one word-sized chunk at a time. 229 */ 230 static unsigned long keyring_get_key_chunk(const void *data, int level) 231 { 232 const struct keyring_index_key *index_key = data; 233 unsigned long chunk = 0; 234 long offset = 0; 235 int desc_len = index_key->desc_len, n = sizeof(chunk); 236 237 level /= ASSOC_ARRAY_KEY_CHUNK_SIZE; 238 switch (level) { 239 case 0: 240 return hash_key_type_and_desc(index_key); 241 case 1: 242 return ((unsigned long)index_key->type << 8) | desc_len; 243 case 2: 244 if (desc_len == 0) 245 return (u8)((unsigned long)index_key->type >> 246 (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8)); 247 n--; 248 offset = 1; 249 default: 250 offset += sizeof(chunk) - 1; 251 offset += (level - 3) * sizeof(chunk); 252 if (offset >= desc_len) 253 return 0; 254 desc_len -= offset; 255 if (desc_len > n) 256 desc_len = n; 257 offset += desc_len; 258 do { 259 chunk <<= 8; 260 chunk |= ((u8*)index_key->description)[--offset]; 261 } while (--desc_len > 0); 262 263 if (level == 2) { 264 chunk <<= 8; 265 chunk |= (u8)((unsigned long)index_key->type >> 266 (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8)); 267 } 268 return chunk; 269 } 270 } 271 272 static unsigned long keyring_get_object_key_chunk(const void *object, int level) 273 { 274 const struct key *key = keyring_ptr_to_key(object); 275 return keyring_get_key_chunk(&key->index_key, level); 276 } 277 278 static bool keyring_compare_object(const void *object, const void *data) 279 { 280 const struct keyring_index_key *index_key = data; 281 const struct key *key = keyring_ptr_to_key(object); 282 283 return key->index_key.type == index_key->type && 284 key->index_key.desc_len == index_key->desc_len && 285 memcmp(key->index_key.description, index_key->description, 286 index_key->desc_len) == 0; 287 } 288 289 /* 290 * Compare the index keys of a pair of objects and determine the bit position 291 * at which they differ - if they differ. 292 */ 293 static int keyring_diff_objects(const void *object, const void *data) 294 { 295 const struct key *key_a = keyring_ptr_to_key(object); 296 const struct keyring_index_key *a = &key_a->index_key; 297 const struct keyring_index_key *b = data; 298 unsigned long seg_a, seg_b; 299 int level, i; 300 301 level = 0; 302 seg_a = hash_key_type_and_desc(a); 303 seg_b = hash_key_type_and_desc(b); 304 if ((seg_a ^ seg_b) != 0) 305 goto differ; 306 307 /* The number of bits contributed by the hash is controlled by a 308 * constant in the assoc_array headers. Everything else thereafter we 309 * can deal with as being machine word-size dependent. 310 */ 311 level += ASSOC_ARRAY_KEY_CHUNK_SIZE / 8; 312 seg_a = a->desc_len; 313 seg_b = b->desc_len; 314 if ((seg_a ^ seg_b) != 0) 315 goto differ; 316 317 /* The next bit may not work on big endian */ 318 level++; 319 seg_a = (unsigned long)a->type; 320 seg_b = (unsigned long)b->type; 321 if ((seg_a ^ seg_b) != 0) 322 goto differ; 323 324 level += sizeof(unsigned long); 325 if (a->desc_len == 0) 326 goto same; 327 328 i = 0; 329 if (((unsigned long)a->description | (unsigned long)b->description) & 330 (sizeof(unsigned long) - 1)) { 331 do { 332 seg_a = *(unsigned long *)(a->description + i); 333 seg_b = *(unsigned long *)(b->description + i); 334 if ((seg_a ^ seg_b) != 0) 335 goto differ_plus_i; 336 i += sizeof(unsigned long); 337 } while (i < (a->desc_len & (sizeof(unsigned long) - 1))); 338 } 339 340 for (; i < a->desc_len; i++) { 341 seg_a = *(unsigned char *)(a->description + i); 342 seg_b = *(unsigned char *)(b->description + i); 343 if ((seg_a ^ seg_b) != 0) 344 goto differ_plus_i; 345 } 346 347 same: 348 return -1; 349 350 differ_plus_i: 351 level += i; 352 differ: 353 i = level * 8 + __ffs(seg_a ^ seg_b); 354 return i; 355 } 356 357 /* 358 * Free an object after stripping the keyring flag off of the pointer. 359 */ 360 static void keyring_free_object(void *object) 361 { 362 key_put(keyring_ptr_to_key(object)); 363 } 364 365 /* 366 * Operations for keyring management by the index-tree routines. 367 */ 368 static const struct assoc_array_ops keyring_assoc_array_ops = { 369 .get_key_chunk = keyring_get_key_chunk, 370 .get_object_key_chunk = keyring_get_object_key_chunk, 371 .compare_object = keyring_compare_object, 372 .diff_objects = keyring_diff_objects, 373 .free_object = keyring_free_object, 374 }; 375 376 /* 377 * Clean up a keyring when it is destroyed. Unpublish its name if it had one 378 * and dispose of its data. 379 * 380 * The garbage collector detects the final key_put(), removes the keyring from 381 * the serial number tree and then does RCU synchronisation before coming here, 382 * so we shouldn't need to worry about code poking around here with the RCU 383 * readlock held by this time. 384 */ 385 static void keyring_destroy(struct key *keyring) 386 { 387 if (keyring->description) { 388 write_lock(&keyring_name_lock); 389 390 if (keyring->name_link.next != NULL && 391 !list_empty(&keyring->name_link)) 392 list_del(&keyring->name_link); 393 394 write_unlock(&keyring_name_lock); 395 } 396 397 if (keyring->restrict_link) { 398 struct key_restriction *keyres = keyring->restrict_link; 399 400 key_put(keyres->key); 401 kfree(keyres); 402 } 403 404 assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops); 405 } 406 407 /* 408 * Describe a keyring for /proc. 409 */ 410 static void keyring_describe(const struct key *keyring, struct seq_file *m) 411 { 412 if (keyring->description) 413 seq_puts(m, keyring->description); 414 else 415 seq_puts(m, "[anon]"); 416 417 if (key_is_positive(keyring)) { 418 if (keyring->keys.nr_leaves_on_tree != 0) 419 seq_printf(m, ": %lu", keyring->keys.nr_leaves_on_tree); 420 else 421 seq_puts(m, ": empty"); 422 } 423 } 424 425 struct keyring_read_iterator_context { 426 size_t buflen; 427 size_t count; 428 key_serial_t __user *buffer; 429 }; 430 431 static int keyring_read_iterator(const void *object, void *data) 432 { 433 struct keyring_read_iterator_context *ctx = data; 434 const struct key *key = keyring_ptr_to_key(object); 435 int ret; 436 437 kenter("{%s,%d},,{%zu/%zu}", 438 key->type->name, key->serial, ctx->count, ctx->buflen); 439 440 if (ctx->count >= ctx->buflen) 441 return 1; 442 443 ret = put_user(key->serial, ctx->buffer); 444 if (ret < 0) 445 return ret; 446 ctx->buffer++; 447 ctx->count += sizeof(key->serial); 448 return 0; 449 } 450 451 /* 452 * Read a list of key IDs from the keyring's contents in binary form 453 * 454 * The keyring's semaphore is read-locked by the caller. This prevents someone 455 * from modifying it under us - which could cause us to read key IDs multiple 456 * times. 457 */ 458 static long keyring_read(const struct key *keyring, 459 char __user *buffer, size_t buflen) 460 { 461 struct keyring_read_iterator_context ctx; 462 long ret; 463 464 kenter("{%d},,%zu", key_serial(keyring), buflen); 465 466 if (buflen & (sizeof(key_serial_t) - 1)) 467 return -EINVAL; 468 469 /* Copy as many key IDs as fit into the buffer */ 470 if (buffer && buflen) { 471 ctx.buffer = (key_serial_t __user *)buffer; 472 ctx.buflen = buflen; 473 ctx.count = 0; 474 ret = assoc_array_iterate(&keyring->keys, 475 keyring_read_iterator, &ctx); 476 if (ret < 0) { 477 kleave(" = %ld [iterate]", ret); 478 return ret; 479 } 480 } 481 482 /* Return the size of the buffer needed */ 483 ret = keyring->keys.nr_leaves_on_tree * sizeof(key_serial_t); 484 if (ret <= buflen) 485 kleave("= %ld [ok]", ret); 486 else 487 kleave("= %ld [buffer too small]", ret); 488 return ret; 489 } 490 491 /* 492 * Allocate a keyring and link into the destination keyring. 493 */ 494 struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid, 495 const struct cred *cred, key_perm_t perm, 496 unsigned long flags, 497 struct key_restriction *restrict_link, 498 struct key *dest) 499 { 500 struct key *keyring; 501 int ret; 502 503 keyring = key_alloc(&key_type_keyring, description, 504 uid, gid, cred, perm, flags, restrict_link); 505 if (!IS_ERR(keyring)) { 506 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL); 507 if (ret < 0) { 508 key_put(keyring); 509 keyring = ERR_PTR(ret); 510 } 511 } 512 513 return keyring; 514 } 515 EXPORT_SYMBOL(keyring_alloc); 516 517 /** 518 * restrict_link_reject - Give -EPERM to restrict link 519 * @keyring: The keyring being added to. 520 * @type: The type of key being added. 521 * @payload: The payload of the key intended to be added. 522 * @data: Additional data for evaluating restriction. 523 * 524 * Reject the addition of any links to a keyring. It can be overridden by 525 * passing KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when 526 * adding a key to a keyring. 527 * 528 * This is meant to be stored in a key_restriction structure which is passed 529 * in the restrict_link parameter to keyring_alloc(). 530 */ 531 int restrict_link_reject(struct key *keyring, 532 const struct key_type *type, 533 const union key_payload *payload, 534 struct key *restriction_key) 535 { 536 return -EPERM; 537 } 538 539 /* 540 * By default, we keys found by getting an exact match on their descriptions. 541 */ 542 bool key_default_cmp(const struct key *key, 543 const struct key_match_data *match_data) 544 { 545 return strcmp(key->description, match_data->raw_data) == 0; 546 } 547 548 /* 549 * Iteration function to consider each key found. 550 */ 551 static int keyring_search_iterator(const void *object, void *iterator_data) 552 { 553 struct keyring_search_context *ctx = iterator_data; 554 const struct key *key = keyring_ptr_to_key(object); 555 unsigned long kflags = READ_ONCE(key->flags); 556 short state = READ_ONCE(key->state); 557 558 kenter("{%d}", key->serial); 559 560 /* ignore keys not of this type */ 561 if (key->type != ctx->index_key.type) { 562 kleave(" = 0 [!type]"); 563 return 0; 564 } 565 566 /* skip invalidated, revoked and expired keys */ 567 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) { 568 time64_t expiry = READ_ONCE(key->expiry); 569 570 if (kflags & ((1 << KEY_FLAG_INVALIDATED) | 571 (1 << KEY_FLAG_REVOKED))) { 572 ctx->result = ERR_PTR(-EKEYREVOKED); 573 kleave(" = %d [invrev]", ctx->skipped_ret); 574 goto skipped; 575 } 576 577 if (expiry && ctx->now >= expiry) { 578 if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED)) 579 ctx->result = ERR_PTR(-EKEYEXPIRED); 580 kleave(" = %d [expire]", ctx->skipped_ret); 581 goto skipped; 582 } 583 } 584 585 /* keys that don't match */ 586 if (!ctx->match_data.cmp(key, &ctx->match_data)) { 587 kleave(" = 0 [!match]"); 588 return 0; 589 } 590 591 /* key must have search permissions */ 592 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) && 593 key_task_permission(make_key_ref(key, ctx->possessed), 594 ctx->cred, KEY_NEED_SEARCH) < 0) { 595 ctx->result = ERR_PTR(-EACCES); 596 kleave(" = %d [!perm]", ctx->skipped_ret); 597 goto skipped; 598 } 599 600 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) { 601 /* we set a different error code if we pass a negative key */ 602 if (state < 0) { 603 ctx->result = ERR_PTR(state); 604 kleave(" = %d [neg]", ctx->skipped_ret); 605 goto skipped; 606 } 607 } 608 609 /* Found */ 610 ctx->result = make_key_ref(key, ctx->possessed); 611 kleave(" = 1 [found]"); 612 return 1; 613 614 skipped: 615 return ctx->skipped_ret; 616 } 617 618 /* 619 * Search inside a keyring for a key. We can search by walking to it 620 * directly based on its index-key or we can iterate over the entire 621 * tree looking for it, based on the match function. 622 */ 623 static int search_keyring(struct key *keyring, struct keyring_search_context *ctx) 624 { 625 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_DIRECT) { 626 const void *object; 627 628 object = assoc_array_find(&keyring->keys, 629 &keyring_assoc_array_ops, 630 &ctx->index_key); 631 return object ? ctx->iterator(object, ctx) : 0; 632 } 633 return assoc_array_iterate(&keyring->keys, ctx->iterator, ctx); 634 } 635 636 /* 637 * Search a tree of keyrings that point to other keyrings up to the maximum 638 * depth. 639 */ 640 static bool search_nested_keyrings(struct key *keyring, 641 struct keyring_search_context *ctx) 642 { 643 struct { 644 struct key *keyring; 645 struct assoc_array_node *node; 646 int slot; 647 } stack[KEYRING_SEARCH_MAX_DEPTH]; 648 649 struct assoc_array_shortcut *shortcut; 650 struct assoc_array_node *node; 651 struct assoc_array_ptr *ptr; 652 struct key *key; 653 int sp = 0, slot; 654 655 kenter("{%d},{%s,%s}", 656 keyring->serial, 657 ctx->index_key.type->name, 658 ctx->index_key.description); 659 660 #define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK) 661 BUG_ON((ctx->flags & STATE_CHECKS) == 0 || 662 (ctx->flags & STATE_CHECKS) == STATE_CHECKS); 663 664 if (ctx->index_key.description) 665 ctx->index_key.desc_len = strlen(ctx->index_key.description); 666 667 /* Check to see if this top-level keyring is what we are looking for 668 * and whether it is valid or not. 669 */ 670 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE || 671 keyring_compare_object(keyring, &ctx->index_key)) { 672 ctx->skipped_ret = 2; 673 switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) { 674 case 1: 675 goto found; 676 case 2: 677 return false; 678 default: 679 break; 680 } 681 } 682 683 ctx->skipped_ret = 0; 684 685 /* Start processing a new keyring */ 686 descend_to_keyring: 687 kdebug("descend to %d", keyring->serial); 688 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) | 689 (1 << KEY_FLAG_REVOKED))) 690 goto not_this_keyring; 691 692 /* Search through the keys in this keyring before its searching its 693 * subtrees. 694 */ 695 if (search_keyring(keyring, ctx)) 696 goto found; 697 698 /* Then manually iterate through the keyrings nested in this one. 699 * 700 * Start from the root node of the index tree. Because of the way the 701 * hash function has been set up, keyrings cluster on the leftmost 702 * branch of the root node (root slot 0) or in the root node itself. 703 * Non-keyrings avoid the leftmost branch of the root entirely (root 704 * slots 1-15). 705 */ 706 ptr = READ_ONCE(keyring->keys.root); 707 if (!ptr) 708 goto not_this_keyring; 709 710 if (assoc_array_ptr_is_shortcut(ptr)) { 711 /* If the root is a shortcut, either the keyring only contains 712 * keyring pointers (everything clusters behind root slot 0) or 713 * doesn't contain any keyring pointers. 714 */ 715 shortcut = assoc_array_ptr_to_shortcut(ptr); 716 if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0) 717 goto not_this_keyring; 718 719 ptr = READ_ONCE(shortcut->next_node); 720 node = assoc_array_ptr_to_node(ptr); 721 goto begin_node; 722 } 723 724 node = assoc_array_ptr_to_node(ptr); 725 ptr = node->slots[0]; 726 if (!assoc_array_ptr_is_meta(ptr)) 727 goto begin_node; 728 729 descend_to_node: 730 /* Descend to a more distal node in this keyring's content tree and go 731 * through that. 732 */ 733 kdebug("descend"); 734 if (assoc_array_ptr_is_shortcut(ptr)) { 735 shortcut = assoc_array_ptr_to_shortcut(ptr); 736 ptr = READ_ONCE(shortcut->next_node); 737 BUG_ON(!assoc_array_ptr_is_node(ptr)); 738 } 739 node = assoc_array_ptr_to_node(ptr); 740 741 begin_node: 742 kdebug("begin_node"); 743 slot = 0; 744 ascend_to_node: 745 /* Go through the slots in a node */ 746 for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) { 747 ptr = READ_ONCE(node->slots[slot]); 748 749 if (assoc_array_ptr_is_meta(ptr) && node->back_pointer) 750 goto descend_to_node; 751 752 if (!keyring_ptr_is_keyring(ptr)) 753 continue; 754 755 key = keyring_ptr_to_key(ptr); 756 757 if (sp >= KEYRING_SEARCH_MAX_DEPTH) { 758 if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) { 759 ctx->result = ERR_PTR(-ELOOP); 760 return false; 761 } 762 goto not_this_keyring; 763 } 764 765 /* Search a nested keyring */ 766 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) && 767 key_task_permission(make_key_ref(key, ctx->possessed), 768 ctx->cred, KEY_NEED_SEARCH) < 0) 769 continue; 770 771 /* stack the current position */ 772 stack[sp].keyring = keyring; 773 stack[sp].node = node; 774 stack[sp].slot = slot; 775 sp++; 776 777 /* begin again with the new keyring */ 778 keyring = key; 779 goto descend_to_keyring; 780 } 781 782 /* We've dealt with all the slots in the current node, so now we need 783 * to ascend to the parent and continue processing there. 784 */ 785 ptr = READ_ONCE(node->back_pointer); 786 slot = node->parent_slot; 787 788 if (ptr && assoc_array_ptr_is_shortcut(ptr)) { 789 shortcut = assoc_array_ptr_to_shortcut(ptr); 790 ptr = READ_ONCE(shortcut->back_pointer); 791 slot = shortcut->parent_slot; 792 } 793 if (!ptr) 794 goto not_this_keyring; 795 node = assoc_array_ptr_to_node(ptr); 796 slot++; 797 798 /* If we've ascended to the root (zero backpointer), we must have just 799 * finished processing the leftmost branch rather than the root slots - 800 * so there can't be any more keyrings for us to find. 801 */ 802 if (node->back_pointer) { 803 kdebug("ascend %d", slot); 804 goto ascend_to_node; 805 } 806 807 /* The keyring we're looking at was disqualified or didn't contain a 808 * matching key. 809 */ 810 not_this_keyring: 811 kdebug("not_this_keyring %d", sp); 812 if (sp <= 0) { 813 kleave(" = false"); 814 return false; 815 } 816 817 /* Resume the processing of a keyring higher up in the tree */ 818 sp--; 819 keyring = stack[sp].keyring; 820 node = stack[sp].node; 821 slot = stack[sp].slot + 1; 822 kdebug("ascend to %d [%d]", keyring->serial, slot); 823 goto ascend_to_node; 824 825 /* We found a viable match */ 826 found: 827 key = key_ref_to_ptr(ctx->result); 828 key_check(key); 829 if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) { 830 key->last_used_at = ctx->now; 831 keyring->last_used_at = ctx->now; 832 while (sp > 0) 833 stack[--sp].keyring->last_used_at = ctx->now; 834 } 835 kleave(" = true"); 836 return true; 837 } 838 839 /** 840 * keyring_search_aux - Search a keyring tree for a key matching some criteria 841 * @keyring_ref: A pointer to the keyring with possession indicator. 842 * @ctx: The keyring search context. 843 * 844 * Search the supplied keyring tree for a key that matches the criteria given. 845 * The root keyring and any linked keyrings must grant Search permission to the 846 * caller to be searchable and keys can only be found if they too grant Search 847 * to the caller. The possession flag on the root keyring pointer controls use 848 * of the possessor bits in permissions checking of the entire tree. In 849 * addition, the LSM gets to forbid keyring searches and key matches. 850 * 851 * The search is performed as a breadth-then-depth search up to the prescribed 852 * limit (KEYRING_SEARCH_MAX_DEPTH). 853 * 854 * Keys are matched to the type provided and are then filtered by the match 855 * function, which is given the description to use in any way it sees fit. The 856 * match function may use any attributes of a key that it wishes to to 857 * determine the match. Normally the match function from the key type would be 858 * used. 859 * 860 * RCU can be used to prevent the keyring key lists from disappearing without 861 * the need to take lots of locks. 862 * 863 * Returns a pointer to the found key and increments the key usage count if 864 * successful; -EAGAIN if no matching keys were found, or if expired or revoked 865 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the 866 * specified keyring wasn't a keyring. 867 * 868 * In the case of a successful return, the possession attribute from 869 * @keyring_ref is propagated to the returned key reference. 870 */ 871 key_ref_t keyring_search_aux(key_ref_t keyring_ref, 872 struct keyring_search_context *ctx) 873 { 874 struct key *keyring; 875 long err; 876 877 ctx->iterator = keyring_search_iterator; 878 ctx->possessed = is_key_possessed(keyring_ref); 879 ctx->result = ERR_PTR(-EAGAIN); 880 881 keyring = key_ref_to_ptr(keyring_ref); 882 key_check(keyring); 883 884 if (keyring->type != &key_type_keyring) 885 return ERR_PTR(-ENOTDIR); 886 887 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) { 888 err = key_task_permission(keyring_ref, ctx->cred, KEY_NEED_SEARCH); 889 if (err < 0) 890 return ERR_PTR(err); 891 } 892 893 rcu_read_lock(); 894 ctx->now = ktime_get_real_seconds(); 895 if (search_nested_keyrings(keyring, ctx)) 896 __key_get(key_ref_to_ptr(ctx->result)); 897 rcu_read_unlock(); 898 return ctx->result; 899 } 900 901 /** 902 * keyring_search - Search the supplied keyring tree for a matching key 903 * @keyring: The root of the keyring tree to be searched. 904 * @type: The type of keyring we want to find. 905 * @description: The name of the keyring we want to find. 906 * 907 * As keyring_search_aux() above, but using the current task's credentials and 908 * type's default matching function and preferred search method. 909 */ 910 key_ref_t keyring_search(key_ref_t keyring, 911 struct key_type *type, 912 const char *description) 913 { 914 struct keyring_search_context ctx = { 915 .index_key.type = type, 916 .index_key.description = description, 917 .cred = current_cred(), 918 .match_data.cmp = key_default_cmp, 919 .match_data.raw_data = description, 920 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT, 921 .flags = KEYRING_SEARCH_DO_STATE_CHECK, 922 }; 923 key_ref_t key; 924 int ret; 925 926 if (type->match_preparse) { 927 ret = type->match_preparse(&ctx.match_data); 928 if (ret < 0) 929 return ERR_PTR(ret); 930 } 931 932 key = keyring_search_aux(keyring, &ctx); 933 934 if (type->match_free) 935 type->match_free(&ctx.match_data); 936 return key; 937 } 938 EXPORT_SYMBOL(keyring_search); 939 940 static struct key_restriction *keyring_restriction_alloc( 941 key_restrict_link_func_t check) 942 { 943 struct key_restriction *keyres = 944 kzalloc(sizeof(struct key_restriction), GFP_KERNEL); 945 946 if (!keyres) 947 return ERR_PTR(-ENOMEM); 948 949 keyres->check = check; 950 951 return keyres; 952 } 953 954 /* 955 * Semaphore to serialise restriction setup to prevent reference count 956 * cycles through restriction key pointers. 957 */ 958 static DECLARE_RWSEM(keyring_serialise_restrict_sem); 959 960 /* 961 * Check for restriction cycles that would prevent keyring garbage collection. 962 * keyring_serialise_restrict_sem must be held. 963 */ 964 static bool keyring_detect_restriction_cycle(const struct key *dest_keyring, 965 struct key_restriction *keyres) 966 { 967 while (keyres && keyres->key && 968 keyres->key->type == &key_type_keyring) { 969 if (keyres->key == dest_keyring) 970 return true; 971 972 keyres = keyres->key->restrict_link; 973 } 974 975 return false; 976 } 977 978 /** 979 * keyring_restrict - Look up and apply a restriction to a keyring 980 * 981 * @keyring: The keyring to be restricted 982 * @restriction: The restriction options to apply to the keyring 983 */ 984 int keyring_restrict(key_ref_t keyring_ref, const char *type, 985 const char *restriction) 986 { 987 struct key *keyring; 988 struct key_type *restrict_type = NULL; 989 struct key_restriction *restrict_link; 990 int ret = 0; 991 992 keyring = key_ref_to_ptr(keyring_ref); 993 key_check(keyring); 994 995 if (keyring->type != &key_type_keyring) 996 return -ENOTDIR; 997 998 if (!type) { 999 restrict_link = keyring_restriction_alloc(restrict_link_reject); 1000 } else { 1001 restrict_type = key_type_lookup(type); 1002 1003 if (IS_ERR(restrict_type)) 1004 return PTR_ERR(restrict_type); 1005 1006 if (!restrict_type->lookup_restriction) { 1007 ret = -ENOENT; 1008 goto error; 1009 } 1010 1011 restrict_link = restrict_type->lookup_restriction(restriction); 1012 } 1013 1014 if (IS_ERR(restrict_link)) { 1015 ret = PTR_ERR(restrict_link); 1016 goto error; 1017 } 1018 1019 down_write(&keyring->sem); 1020 down_write(&keyring_serialise_restrict_sem); 1021 1022 if (keyring->restrict_link) 1023 ret = -EEXIST; 1024 else if (keyring_detect_restriction_cycle(keyring, restrict_link)) 1025 ret = -EDEADLK; 1026 else 1027 keyring->restrict_link = restrict_link; 1028 1029 up_write(&keyring_serialise_restrict_sem); 1030 up_write(&keyring->sem); 1031 1032 if (ret < 0) { 1033 key_put(restrict_link->key); 1034 kfree(restrict_link); 1035 } 1036 1037 error: 1038 if (restrict_type) 1039 key_type_put(restrict_type); 1040 1041 return ret; 1042 } 1043 EXPORT_SYMBOL(keyring_restrict); 1044 1045 /* 1046 * Search the given keyring for a key that might be updated. 1047 * 1048 * The caller must guarantee that the keyring is a keyring and that the 1049 * permission is granted to modify the keyring as no check is made here. The 1050 * caller must also hold a lock on the keyring semaphore. 1051 * 1052 * Returns a pointer to the found key with usage count incremented if 1053 * successful and returns NULL if not found. Revoked and invalidated keys are 1054 * skipped over. 1055 * 1056 * If successful, the possession indicator is propagated from the keyring ref 1057 * to the returned key reference. 1058 */ 1059 key_ref_t find_key_to_update(key_ref_t keyring_ref, 1060 const struct keyring_index_key *index_key) 1061 { 1062 struct key *keyring, *key; 1063 const void *object; 1064 1065 keyring = key_ref_to_ptr(keyring_ref); 1066 1067 kenter("{%d},{%s,%s}", 1068 keyring->serial, index_key->type->name, index_key->description); 1069 1070 object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops, 1071 index_key); 1072 1073 if (object) 1074 goto found; 1075 1076 kleave(" = NULL"); 1077 return NULL; 1078 1079 found: 1080 key = keyring_ptr_to_key(object); 1081 if (key->flags & ((1 << KEY_FLAG_INVALIDATED) | 1082 (1 << KEY_FLAG_REVOKED))) { 1083 kleave(" = NULL [x]"); 1084 return NULL; 1085 } 1086 __key_get(key); 1087 kleave(" = {%d}", key->serial); 1088 return make_key_ref(key, is_key_possessed(keyring_ref)); 1089 } 1090 1091 /* 1092 * Find a keyring with the specified name. 1093 * 1094 * Only keyrings that have nonzero refcount, are not revoked, and are owned by a 1095 * user in the current user namespace are considered. If @uid_keyring is %true, 1096 * the keyring additionally must have been allocated as a user or user session 1097 * keyring; otherwise, it must grant Search permission directly to the caller. 1098 * 1099 * Returns a pointer to the keyring with the keyring's refcount having being 1100 * incremented on success. -ENOKEY is returned if a key could not be found. 1101 */ 1102 struct key *find_keyring_by_name(const char *name, bool uid_keyring) 1103 { 1104 struct key *keyring; 1105 int bucket; 1106 1107 if (!name) 1108 return ERR_PTR(-EINVAL); 1109 1110 bucket = keyring_hash(name); 1111 1112 read_lock(&keyring_name_lock); 1113 1114 if (keyring_name_hash[bucket].next) { 1115 /* search this hash bucket for a keyring with a matching name 1116 * that's readable and that hasn't been revoked */ 1117 list_for_each_entry(keyring, 1118 &keyring_name_hash[bucket], 1119 name_link 1120 ) { 1121 if (!kuid_has_mapping(current_user_ns(), keyring->user->uid)) 1122 continue; 1123 1124 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) 1125 continue; 1126 1127 if (strcmp(keyring->description, name) != 0) 1128 continue; 1129 1130 if (uid_keyring) { 1131 if (!test_bit(KEY_FLAG_UID_KEYRING, 1132 &keyring->flags)) 1133 continue; 1134 } else { 1135 if (key_permission(make_key_ref(keyring, 0), 1136 KEY_NEED_SEARCH) < 0) 1137 continue; 1138 } 1139 1140 /* we've got a match but we might end up racing with 1141 * key_cleanup() if the keyring is currently 'dead' 1142 * (ie. it has a zero usage count) */ 1143 if (!refcount_inc_not_zero(&keyring->usage)) 1144 continue; 1145 keyring->last_used_at = ktime_get_real_seconds(); 1146 goto out; 1147 } 1148 } 1149 1150 keyring = ERR_PTR(-ENOKEY); 1151 out: 1152 read_unlock(&keyring_name_lock); 1153 return keyring; 1154 } 1155 1156 static int keyring_detect_cycle_iterator(const void *object, 1157 void *iterator_data) 1158 { 1159 struct keyring_search_context *ctx = iterator_data; 1160 const struct key *key = keyring_ptr_to_key(object); 1161 1162 kenter("{%d}", key->serial); 1163 1164 /* We might get a keyring with matching index-key that is nonetheless a 1165 * different keyring. */ 1166 if (key != ctx->match_data.raw_data) 1167 return 0; 1168 1169 ctx->result = ERR_PTR(-EDEADLK); 1170 return 1; 1171 } 1172 1173 /* 1174 * See if a cycle will will be created by inserting acyclic tree B in acyclic 1175 * tree A at the topmost level (ie: as a direct child of A). 1176 * 1177 * Since we are adding B to A at the top level, checking for cycles should just 1178 * be a matter of seeing if node A is somewhere in tree B. 1179 */ 1180 static int keyring_detect_cycle(struct key *A, struct key *B) 1181 { 1182 struct keyring_search_context ctx = { 1183 .index_key = A->index_key, 1184 .match_data.raw_data = A, 1185 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT, 1186 .iterator = keyring_detect_cycle_iterator, 1187 .flags = (KEYRING_SEARCH_NO_STATE_CHECK | 1188 KEYRING_SEARCH_NO_UPDATE_TIME | 1189 KEYRING_SEARCH_NO_CHECK_PERM | 1190 KEYRING_SEARCH_DETECT_TOO_DEEP), 1191 }; 1192 1193 rcu_read_lock(); 1194 search_nested_keyrings(B, &ctx); 1195 rcu_read_unlock(); 1196 return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result); 1197 } 1198 1199 /* 1200 * Preallocate memory so that a key can be linked into to a keyring. 1201 */ 1202 int __key_link_begin(struct key *keyring, 1203 const struct keyring_index_key *index_key, 1204 struct assoc_array_edit **_edit) 1205 __acquires(&keyring->sem) 1206 __acquires(&keyring_serialise_link_sem) 1207 { 1208 struct assoc_array_edit *edit; 1209 int ret; 1210 1211 kenter("%d,%s,%s,", 1212 keyring->serial, index_key->type->name, index_key->description); 1213 1214 BUG_ON(index_key->desc_len == 0); 1215 1216 if (keyring->type != &key_type_keyring) 1217 return -ENOTDIR; 1218 1219 down_write(&keyring->sem); 1220 1221 ret = -EKEYREVOKED; 1222 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) 1223 goto error_krsem; 1224 1225 /* serialise link/link calls to prevent parallel calls causing a cycle 1226 * when linking two keyring in opposite orders */ 1227 if (index_key->type == &key_type_keyring) 1228 down_write(&keyring_serialise_link_sem); 1229 1230 /* Create an edit script that will insert/replace the key in the 1231 * keyring tree. 1232 */ 1233 edit = assoc_array_insert(&keyring->keys, 1234 &keyring_assoc_array_ops, 1235 index_key, 1236 NULL); 1237 if (IS_ERR(edit)) { 1238 ret = PTR_ERR(edit); 1239 goto error_sem; 1240 } 1241 1242 /* If we're not replacing a link in-place then we're going to need some 1243 * extra quota. 1244 */ 1245 if (!edit->dead_leaf) { 1246 ret = key_payload_reserve(keyring, 1247 keyring->datalen + KEYQUOTA_LINK_BYTES); 1248 if (ret < 0) 1249 goto error_cancel; 1250 } 1251 1252 *_edit = edit; 1253 kleave(" = 0"); 1254 return 0; 1255 1256 error_cancel: 1257 assoc_array_cancel_edit(edit); 1258 error_sem: 1259 if (index_key->type == &key_type_keyring) 1260 up_write(&keyring_serialise_link_sem); 1261 error_krsem: 1262 up_write(&keyring->sem); 1263 kleave(" = %d", ret); 1264 return ret; 1265 } 1266 1267 /* 1268 * Check already instantiated keys aren't going to be a problem. 1269 * 1270 * The caller must have called __key_link_begin(). Don't need to call this for 1271 * keys that were created since __key_link_begin() was called. 1272 */ 1273 int __key_link_check_live_key(struct key *keyring, struct key *key) 1274 { 1275 if (key->type == &key_type_keyring) 1276 /* check that we aren't going to create a cycle by linking one 1277 * keyring to another */ 1278 return keyring_detect_cycle(keyring, key); 1279 return 0; 1280 } 1281 1282 /* 1283 * Link a key into to a keyring. 1284 * 1285 * Must be called with __key_link_begin() having being called. Discards any 1286 * already extant link to matching key if there is one, so that each keyring 1287 * holds at most one link to any given key of a particular type+description 1288 * combination. 1289 */ 1290 void __key_link(struct key *key, struct assoc_array_edit **_edit) 1291 { 1292 __key_get(key); 1293 assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key)); 1294 assoc_array_apply_edit(*_edit); 1295 *_edit = NULL; 1296 } 1297 1298 /* 1299 * Finish linking a key into to a keyring. 1300 * 1301 * Must be called with __key_link_begin() having being called. 1302 */ 1303 void __key_link_end(struct key *keyring, 1304 const struct keyring_index_key *index_key, 1305 struct assoc_array_edit *edit) 1306 __releases(&keyring->sem) 1307 __releases(&keyring_serialise_link_sem) 1308 { 1309 BUG_ON(index_key->type == NULL); 1310 kenter("%d,%s,", keyring->serial, index_key->type->name); 1311 1312 if (index_key->type == &key_type_keyring) 1313 up_write(&keyring_serialise_link_sem); 1314 1315 if (edit) { 1316 if (!edit->dead_leaf) { 1317 key_payload_reserve(keyring, 1318 keyring->datalen - KEYQUOTA_LINK_BYTES); 1319 } 1320 assoc_array_cancel_edit(edit); 1321 } 1322 up_write(&keyring->sem); 1323 } 1324 1325 /* 1326 * Check addition of keys to restricted keyrings. 1327 */ 1328 static int __key_link_check_restriction(struct key *keyring, struct key *key) 1329 { 1330 if (!keyring->restrict_link || !keyring->restrict_link->check) 1331 return 0; 1332 return keyring->restrict_link->check(keyring, key->type, &key->payload, 1333 keyring->restrict_link->key); 1334 } 1335 1336 /** 1337 * key_link - Link a key to a keyring 1338 * @keyring: The keyring to make the link in. 1339 * @key: The key to link to. 1340 * 1341 * Make a link in a keyring to a key, such that the keyring holds a reference 1342 * on that key and the key can potentially be found by searching that keyring. 1343 * 1344 * This function will write-lock the keyring's semaphore and will consume some 1345 * of the user's key data quota to hold the link. 1346 * 1347 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, 1348 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is 1349 * full, -EDQUOT if there is insufficient key data quota remaining to add 1350 * another link or -ENOMEM if there's insufficient memory. 1351 * 1352 * It is assumed that the caller has checked that it is permitted for a link to 1353 * be made (the keyring should have Write permission and the key Link 1354 * permission). 1355 */ 1356 int key_link(struct key *keyring, struct key *key) 1357 { 1358 struct assoc_array_edit *edit; 1359 int ret; 1360 1361 kenter("{%d,%d}", keyring->serial, refcount_read(&keyring->usage)); 1362 1363 key_check(keyring); 1364 key_check(key); 1365 1366 ret = __key_link_begin(keyring, &key->index_key, &edit); 1367 if (ret == 0) { 1368 kdebug("begun {%d,%d}", keyring->serial, refcount_read(&keyring->usage)); 1369 ret = __key_link_check_restriction(keyring, key); 1370 if (ret == 0) 1371 ret = __key_link_check_live_key(keyring, key); 1372 if (ret == 0) 1373 __key_link(key, &edit); 1374 __key_link_end(keyring, &key->index_key, edit); 1375 } 1376 1377 kleave(" = %d {%d,%d}", ret, keyring->serial, refcount_read(&keyring->usage)); 1378 return ret; 1379 } 1380 EXPORT_SYMBOL(key_link); 1381 1382 /** 1383 * key_unlink - Unlink the first link to a key from a keyring. 1384 * @keyring: The keyring to remove the link from. 1385 * @key: The key the link is to. 1386 * 1387 * Remove a link from a keyring to a key. 1388 * 1389 * This function will write-lock the keyring's semaphore. 1390 * 1391 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if 1392 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient 1393 * memory. 1394 * 1395 * It is assumed that the caller has checked that it is permitted for a link to 1396 * be removed (the keyring should have Write permission; no permissions are 1397 * required on the key). 1398 */ 1399 int key_unlink(struct key *keyring, struct key *key) 1400 { 1401 struct assoc_array_edit *edit; 1402 int ret; 1403 1404 key_check(keyring); 1405 key_check(key); 1406 1407 if (keyring->type != &key_type_keyring) 1408 return -ENOTDIR; 1409 1410 down_write(&keyring->sem); 1411 1412 edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops, 1413 &key->index_key); 1414 if (IS_ERR(edit)) { 1415 ret = PTR_ERR(edit); 1416 goto error; 1417 } 1418 ret = -ENOENT; 1419 if (edit == NULL) 1420 goto error; 1421 1422 assoc_array_apply_edit(edit); 1423 key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES); 1424 ret = 0; 1425 1426 error: 1427 up_write(&keyring->sem); 1428 return ret; 1429 } 1430 EXPORT_SYMBOL(key_unlink); 1431 1432 /** 1433 * keyring_clear - Clear a keyring 1434 * @keyring: The keyring to clear. 1435 * 1436 * Clear the contents of the specified keyring. 1437 * 1438 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring. 1439 */ 1440 int keyring_clear(struct key *keyring) 1441 { 1442 struct assoc_array_edit *edit; 1443 int ret; 1444 1445 if (keyring->type != &key_type_keyring) 1446 return -ENOTDIR; 1447 1448 down_write(&keyring->sem); 1449 1450 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops); 1451 if (IS_ERR(edit)) { 1452 ret = PTR_ERR(edit); 1453 } else { 1454 if (edit) 1455 assoc_array_apply_edit(edit); 1456 key_payload_reserve(keyring, 0); 1457 ret = 0; 1458 } 1459 1460 up_write(&keyring->sem); 1461 return ret; 1462 } 1463 EXPORT_SYMBOL(keyring_clear); 1464 1465 /* 1466 * Dispose of the links from a revoked keyring. 1467 * 1468 * This is called with the key sem write-locked. 1469 */ 1470 static void keyring_revoke(struct key *keyring) 1471 { 1472 struct assoc_array_edit *edit; 1473 1474 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops); 1475 if (!IS_ERR(edit)) { 1476 if (edit) 1477 assoc_array_apply_edit(edit); 1478 key_payload_reserve(keyring, 0); 1479 } 1480 } 1481 1482 static bool keyring_gc_select_iterator(void *object, void *iterator_data) 1483 { 1484 struct key *key = keyring_ptr_to_key(object); 1485 time64_t *limit = iterator_data; 1486 1487 if (key_is_dead(key, *limit)) 1488 return false; 1489 key_get(key); 1490 return true; 1491 } 1492 1493 static int keyring_gc_check_iterator(const void *object, void *iterator_data) 1494 { 1495 const struct key *key = keyring_ptr_to_key(object); 1496 time64_t *limit = iterator_data; 1497 1498 key_check(key); 1499 return key_is_dead(key, *limit); 1500 } 1501 1502 /* 1503 * Garbage collect pointers from a keyring. 1504 * 1505 * Not called with any locks held. The keyring's key struct will not be 1506 * deallocated under us as only our caller may deallocate it. 1507 */ 1508 void keyring_gc(struct key *keyring, time64_t limit) 1509 { 1510 int result; 1511 1512 kenter("%x{%s}", keyring->serial, keyring->description ?: ""); 1513 1514 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) | 1515 (1 << KEY_FLAG_REVOKED))) 1516 goto dont_gc; 1517 1518 /* scan the keyring looking for dead keys */ 1519 rcu_read_lock(); 1520 result = assoc_array_iterate(&keyring->keys, 1521 keyring_gc_check_iterator, &limit); 1522 rcu_read_unlock(); 1523 if (result == true) 1524 goto do_gc; 1525 1526 dont_gc: 1527 kleave(" [no gc]"); 1528 return; 1529 1530 do_gc: 1531 down_write(&keyring->sem); 1532 assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops, 1533 keyring_gc_select_iterator, &limit); 1534 up_write(&keyring->sem); 1535 kleave(" [gc]"); 1536 } 1537 1538 /* 1539 * Garbage collect restriction pointers from a keyring. 1540 * 1541 * Keyring restrictions are associated with a key type, and must be cleaned 1542 * up if the key type is unregistered. The restriction is altered to always 1543 * reject additional keys so a keyring cannot be opened up by unregistering 1544 * a key type. 1545 * 1546 * Not called with any keyring locks held. The keyring's key struct will not 1547 * be deallocated under us as only our caller may deallocate it. 1548 * 1549 * The caller is required to hold key_types_sem and dead_type->sem. This is 1550 * fulfilled by key_gc_keytype() holding the locks on behalf of 1551 * key_garbage_collector(), which it invokes on a workqueue. 1552 */ 1553 void keyring_restriction_gc(struct key *keyring, struct key_type *dead_type) 1554 { 1555 struct key_restriction *keyres; 1556 1557 kenter("%x{%s}", keyring->serial, keyring->description ?: ""); 1558 1559 /* 1560 * keyring->restrict_link is only assigned at key allocation time 1561 * or with the key type locked, so the only values that could be 1562 * concurrently assigned to keyring->restrict_link are for key 1563 * types other than dead_type. Given this, it's ok to check 1564 * the key type before acquiring keyring->sem. 1565 */ 1566 if (!dead_type || !keyring->restrict_link || 1567 keyring->restrict_link->keytype != dead_type) { 1568 kleave(" [no restriction gc]"); 1569 return; 1570 } 1571 1572 /* Lock the keyring to ensure that a link is not in progress */ 1573 down_write(&keyring->sem); 1574 1575 keyres = keyring->restrict_link; 1576 1577 keyres->check = restrict_link_reject; 1578 1579 key_put(keyres->key); 1580 keyres->key = NULL; 1581 keyres->keytype = NULL; 1582 1583 up_write(&keyring->sem); 1584 1585 kleave(" [restriction gc]"); 1586 } 1587