| 1 | /* Keyring handling |
| 2 | * |
| 3 | * Copyright (C) 2004-2005, 2008 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/module.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 <linux/uaccess.h> |
| 21 | #include "internal.h" |
| 22 | |
| 23 | #define rcu_dereference_locked_keyring(keyring) \ |
| 24 | (rcu_dereference_protected( \ |
| 25 | (keyring)->payload.subscriptions, \ |
| 26 | rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem))) |
| 27 | |
| 28 | #define rcu_deref_link_locked(klist, index, keyring) \ |
| 29 | (rcu_dereference_protected( \ |
| 30 | (klist)->keys[index], \ |
| 31 | rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem))) |
| 32 | |
| 33 | #define MAX_KEYRING_LINKS \ |
| 34 | min_t(size_t, USHRT_MAX - 1, \ |
| 35 | ((PAGE_SIZE - sizeof(struct keyring_list)) / sizeof(struct key *))) |
| 36 | |
| 37 | #define KEY_LINK_FIXQUOTA 1UL |
| 38 | |
| 39 | /* |
| 40 | * When plumbing the depths of the key tree, this sets a hard limit |
| 41 | * set on how deep we're willing to go. |
| 42 | */ |
| 43 | #define KEYRING_SEARCH_MAX_DEPTH 6 |
| 44 | |
| 45 | /* |
| 46 | * We keep all named keyrings in a hash to speed looking them up. |
| 47 | */ |
| 48 | #define KEYRING_NAME_HASH_SIZE (1 << 5) |
| 49 | |
| 50 | static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE]; |
| 51 | static DEFINE_RWLOCK(keyring_name_lock); |
| 52 | |
| 53 | static inline unsigned keyring_hash(const char *desc) |
| 54 | { |
| 55 | unsigned bucket = 0; |
| 56 | |
| 57 | for (; *desc; desc++) |
| 58 | bucket += (unsigned char)*desc; |
| 59 | |
| 60 | return bucket & (KEYRING_NAME_HASH_SIZE - 1); |
| 61 | } |
| 62 | |
| 63 | /* |
| 64 | * The keyring key type definition. Keyrings are simply keys of this type and |
| 65 | * can be treated as ordinary keys in addition to having their own special |
| 66 | * operations. |
| 67 | */ |
| 68 | static int keyring_instantiate(struct key *keyring, |
| 69 | struct key_preparsed_payload *prep); |
| 70 | static int keyring_match(const struct key *keyring, const void *criterion); |
| 71 | static void keyring_revoke(struct key *keyring); |
| 72 | static void keyring_destroy(struct key *keyring); |
| 73 | static void keyring_describe(const struct key *keyring, struct seq_file *m); |
| 74 | static long keyring_read(const struct key *keyring, |
| 75 | char __user *buffer, size_t buflen); |
| 76 | |
| 77 | struct key_type key_type_keyring = { |
| 78 | .name = "keyring", |
| 79 | .def_datalen = sizeof(struct keyring_list), |
| 80 | .instantiate = keyring_instantiate, |
| 81 | .match = keyring_match, |
| 82 | .revoke = keyring_revoke, |
| 83 | .destroy = keyring_destroy, |
| 84 | .describe = keyring_describe, |
| 85 | .read = keyring_read, |
| 86 | }; |
| 87 | EXPORT_SYMBOL(key_type_keyring); |
| 88 | |
| 89 | /* |
| 90 | * Semaphore to serialise link/link calls to prevent two link calls in parallel |
| 91 | * introducing a cycle. |
| 92 | */ |
| 93 | static DECLARE_RWSEM(keyring_serialise_link_sem); |
| 94 | |
| 95 | /* |
| 96 | * Publish the name of a keyring so that it can be found by name (if it has |
| 97 | * one). |
| 98 | */ |
| 99 | static void keyring_publish_name(struct key *keyring) |
| 100 | { |
| 101 | int bucket; |
| 102 | |
| 103 | if (keyring->description) { |
| 104 | bucket = keyring_hash(keyring->description); |
| 105 | |
| 106 | write_lock(&keyring_name_lock); |
| 107 | |
| 108 | if (!keyring_name_hash[bucket].next) |
| 109 | INIT_LIST_HEAD(&keyring_name_hash[bucket]); |
| 110 | |
| 111 | list_add_tail(&keyring->type_data.link, |
| 112 | &keyring_name_hash[bucket]); |
| 113 | |
| 114 | write_unlock(&keyring_name_lock); |
| 115 | } |
| 116 | } |
| 117 | |
| 118 | /* |
| 119 | * Initialise a keyring. |
| 120 | * |
| 121 | * Returns 0 on success, -EINVAL if given any data. |
| 122 | */ |
| 123 | static int keyring_instantiate(struct key *keyring, |
| 124 | struct key_preparsed_payload *prep) |
| 125 | { |
| 126 | int ret; |
| 127 | |
| 128 | ret = -EINVAL; |
| 129 | if (prep->datalen == 0) { |
| 130 | /* make the keyring available by name if it has one */ |
| 131 | keyring_publish_name(keyring); |
| 132 | ret = 0; |
| 133 | } |
| 134 | |
| 135 | return ret; |
| 136 | } |
| 137 | |
| 138 | /* |
| 139 | * Match keyrings on their name |
| 140 | */ |
| 141 | static int keyring_match(const struct key *keyring, const void *description) |
| 142 | { |
| 143 | return keyring->description && |
| 144 | strcmp(keyring->description, description) == 0; |
| 145 | } |
| 146 | |
| 147 | /* |
| 148 | * Clean up a keyring when it is destroyed. Unpublish its name if it had one |
| 149 | * and dispose of its data. |
| 150 | * |
| 151 | * The garbage collector detects the final key_put(), removes the keyring from |
| 152 | * the serial number tree and then does RCU synchronisation before coming here, |
| 153 | * so we shouldn't need to worry about code poking around here with the RCU |
| 154 | * readlock held by this time. |
| 155 | */ |
| 156 | static void keyring_destroy(struct key *keyring) |
| 157 | { |
| 158 | struct keyring_list *klist; |
| 159 | int loop; |
| 160 | |
| 161 | if (keyring->description) { |
| 162 | write_lock(&keyring_name_lock); |
| 163 | |
| 164 | if (keyring->type_data.link.next != NULL && |
| 165 | !list_empty(&keyring->type_data.link)) |
| 166 | list_del(&keyring->type_data.link); |
| 167 | |
| 168 | write_unlock(&keyring_name_lock); |
| 169 | } |
| 170 | |
| 171 | klist = rcu_access_pointer(keyring->payload.subscriptions); |
| 172 | if (klist) { |
| 173 | for (loop = klist->nkeys - 1; loop >= 0; loop--) |
| 174 | key_put(rcu_access_pointer(klist->keys[loop])); |
| 175 | kfree(klist); |
| 176 | } |
| 177 | } |
| 178 | |
| 179 | /* |
| 180 | * Describe a keyring for /proc. |
| 181 | */ |
| 182 | static void keyring_describe(const struct key *keyring, struct seq_file *m) |
| 183 | { |
| 184 | struct keyring_list *klist; |
| 185 | |
| 186 | if (keyring->description) |
| 187 | seq_puts(m, keyring->description); |
| 188 | else |
| 189 | seq_puts(m, "[anon]"); |
| 190 | |
| 191 | if (key_is_instantiated(keyring)) { |
| 192 | rcu_read_lock(); |
| 193 | klist = rcu_dereference(keyring->payload.subscriptions); |
| 194 | if (klist) |
| 195 | seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys); |
| 196 | else |
| 197 | seq_puts(m, ": empty"); |
| 198 | rcu_read_unlock(); |
| 199 | } |
| 200 | } |
| 201 | |
| 202 | /* |
| 203 | * Read a list of key IDs from the keyring's contents in binary form |
| 204 | * |
| 205 | * The keyring's semaphore is read-locked by the caller. |
| 206 | */ |
| 207 | static long keyring_read(const struct key *keyring, |
| 208 | char __user *buffer, size_t buflen) |
| 209 | { |
| 210 | struct keyring_list *klist; |
| 211 | struct key *key; |
| 212 | size_t qty, tmp; |
| 213 | int loop, ret; |
| 214 | |
| 215 | ret = 0; |
| 216 | klist = rcu_dereference_locked_keyring(keyring); |
| 217 | if (klist) { |
| 218 | /* calculate how much data we could return */ |
| 219 | qty = klist->nkeys * sizeof(key_serial_t); |
| 220 | |
| 221 | if (buffer && buflen > 0) { |
| 222 | if (buflen > qty) |
| 223 | buflen = qty; |
| 224 | |
| 225 | /* copy the IDs of the subscribed keys into the |
| 226 | * buffer */ |
| 227 | ret = -EFAULT; |
| 228 | |
| 229 | for (loop = 0; loop < klist->nkeys; loop++) { |
| 230 | key = rcu_deref_link_locked(klist, loop, |
| 231 | keyring); |
| 232 | |
| 233 | tmp = sizeof(key_serial_t); |
| 234 | if (tmp > buflen) |
| 235 | tmp = buflen; |
| 236 | |
| 237 | if (copy_to_user(buffer, |
| 238 | &key->serial, |
| 239 | tmp) != 0) |
| 240 | goto error; |
| 241 | |
| 242 | buflen -= tmp; |
| 243 | if (buflen == 0) |
| 244 | break; |
| 245 | buffer += tmp; |
| 246 | } |
| 247 | } |
| 248 | |
| 249 | ret = qty; |
| 250 | } |
| 251 | |
| 252 | error: |
| 253 | return ret; |
| 254 | } |
| 255 | |
| 256 | /* |
| 257 | * Allocate a keyring and link into the destination keyring. |
| 258 | */ |
| 259 | struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid, |
| 260 | const struct cred *cred, key_perm_t perm, |
| 261 | unsigned long flags, struct key *dest) |
| 262 | { |
| 263 | struct key *keyring; |
| 264 | int ret; |
| 265 | |
| 266 | keyring = key_alloc(&key_type_keyring, description, |
| 267 | uid, gid, cred, perm, flags); |
| 268 | if (!IS_ERR(keyring)) { |
| 269 | ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL); |
| 270 | if (ret < 0) { |
| 271 | key_put(keyring); |
| 272 | keyring = ERR_PTR(ret); |
| 273 | } |
| 274 | } |
| 275 | |
| 276 | return keyring; |
| 277 | } |
| 278 | EXPORT_SYMBOL(keyring_alloc); |
| 279 | |
| 280 | /** |
| 281 | * keyring_search_aux - Search a keyring tree for a key matching some criteria |
| 282 | * @keyring_ref: A pointer to the keyring with possession indicator. |
| 283 | * @cred: The credentials to use for permissions checks. |
| 284 | * @type: The type of key to search for. |
| 285 | * @description: Parameter for @match. |
| 286 | * @match: Function to rule on whether or not a key is the one required. |
| 287 | * @no_state_check: Don't check if a matching key is bad |
| 288 | * |
| 289 | * Search the supplied keyring tree for a key that matches the criteria given. |
| 290 | * The root keyring and any linked keyrings must grant Search permission to the |
| 291 | * caller to be searchable and keys can only be found if they too grant Search |
| 292 | * to the caller. The possession flag on the root keyring pointer controls use |
| 293 | * of the possessor bits in permissions checking of the entire tree. In |
| 294 | * addition, the LSM gets to forbid keyring searches and key matches. |
| 295 | * |
| 296 | * The search is performed as a breadth-then-depth search up to the prescribed |
| 297 | * limit (KEYRING_SEARCH_MAX_DEPTH). |
| 298 | * |
| 299 | * Keys are matched to the type provided and are then filtered by the match |
| 300 | * function, which is given the description to use in any way it sees fit. The |
| 301 | * match function may use any attributes of a key that it wishes to to |
| 302 | * determine the match. Normally the match function from the key type would be |
| 303 | * used. |
| 304 | * |
| 305 | * RCU is used to prevent the keyring key lists from disappearing without the |
| 306 | * need to take lots of locks. |
| 307 | * |
| 308 | * Returns a pointer to the found key and increments the key usage count if |
| 309 | * successful; -EAGAIN if no matching keys were found, or if expired or revoked |
| 310 | * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the |
| 311 | * specified keyring wasn't a keyring. |
| 312 | * |
| 313 | * In the case of a successful return, the possession attribute from |
| 314 | * @keyring_ref is propagated to the returned key reference. |
| 315 | */ |
| 316 | key_ref_t keyring_search_aux(key_ref_t keyring_ref, |
| 317 | const struct cred *cred, |
| 318 | struct key_type *type, |
| 319 | const void *description, |
| 320 | key_match_func_t match, |
| 321 | bool no_state_check) |
| 322 | { |
| 323 | struct { |
| 324 | /* Need a separate keylist pointer for RCU purposes */ |
| 325 | struct key *keyring; |
| 326 | struct keyring_list *keylist; |
| 327 | int kix; |
| 328 | } stack[KEYRING_SEARCH_MAX_DEPTH]; |
| 329 | |
| 330 | struct keyring_list *keylist; |
| 331 | struct timespec now; |
| 332 | unsigned long possessed, kflags; |
| 333 | struct key *keyring, *key; |
| 334 | key_ref_t key_ref; |
| 335 | long err; |
| 336 | int sp, nkeys, kix; |
| 337 | |
| 338 | keyring = key_ref_to_ptr(keyring_ref); |
| 339 | possessed = is_key_possessed(keyring_ref); |
| 340 | key_check(keyring); |
| 341 | |
| 342 | /* top keyring must have search permission to begin the search */ |
| 343 | err = key_task_permission(keyring_ref, cred, KEY_SEARCH); |
| 344 | if (err < 0) { |
| 345 | key_ref = ERR_PTR(err); |
| 346 | goto error; |
| 347 | } |
| 348 | |
| 349 | key_ref = ERR_PTR(-ENOTDIR); |
| 350 | if (keyring->type != &key_type_keyring) |
| 351 | goto error; |
| 352 | |
| 353 | rcu_read_lock(); |
| 354 | |
| 355 | now = current_kernel_time(); |
| 356 | err = -EAGAIN; |
| 357 | sp = 0; |
| 358 | |
| 359 | /* firstly we should check to see if this top-level keyring is what we |
| 360 | * are looking for */ |
| 361 | key_ref = ERR_PTR(-EAGAIN); |
| 362 | kflags = keyring->flags; |
| 363 | if (keyring->type == type && match(keyring, description)) { |
| 364 | key = keyring; |
| 365 | if (no_state_check) |
| 366 | goto found; |
| 367 | |
| 368 | /* check it isn't negative and hasn't expired or been |
| 369 | * revoked */ |
| 370 | if (kflags & (1 << KEY_FLAG_REVOKED)) |
| 371 | goto error_2; |
| 372 | if (key->expiry && now.tv_sec >= key->expiry) |
| 373 | goto error_2; |
| 374 | key_ref = ERR_PTR(key->type_data.reject_error); |
| 375 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) |
| 376 | goto error_2; |
| 377 | goto found; |
| 378 | } |
| 379 | |
| 380 | /* otherwise, the top keyring must not be revoked, expired, or |
| 381 | * negatively instantiated if we are to search it */ |
| 382 | key_ref = ERR_PTR(-EAGAIN); |
| 383 | if (kflags & ((1 << KEY_FLAG_INVALIDATED) | |
| 384 | (1 << KEY_FLAG_REVOKED) | |
| 385 | (1 << KEY_FLAG_NEGATIVE)) || |
| 386 | (keyring->expiry && now.tv_sec >= keyring->expiry)) |
| 387 | goto error_2; |
| 388 | |
| 389 | /* start processing a new keyring */ |
| 390 | descend: |
| 391 | kflags = keyring->flags; |
| 392 | if (kflags & ((1 << KEY_FLAG_INVALIDATED) | |
| 393 | (1 << KEY_FLAG_REVOKED))) |
| 394 | goto not_this_keyring; |
| 395 | |
| 396 | keylist = rcu_dereference(keyring->payload.subscriptions); |
| 397 | if (!keylist) |
| 398 | goto not_this_keyring; |
| 399 | |
| 400 | /* iterate through the keys in this keyring first */ |
| 401 | nkeys = keylist->nkeys; |
| 402 | smp_rmb(); |
| 403 | for (kix = 0; kix < nkeys; kix++) { |
| 404 | key = rcu_dereference(keylist->keys[kix]); |
| 405 | kflags = key->flags; |
| 406 | |
| 407 | /* ignore keys not of this type */ |
| 408 | if (key->type != type) |
| 409 | continue; |
| 410 | |
| 411 | /* skip invalidated, revoked and expired keys */ |
| 412 | if (!no_state_check) { |
| 413 | if (kflags & ((1 << KEY_FLAG_INVALIDATED) | |
| 414 | (1 << KEY_FLAG_REVOKED))) |
| 415 | continue; |
| 416 | |
| 417 | if (key->expiry && now.tv_sec >= key->expiry) |
| 418 | continue; |
| 419 | } |
| 420 | |
| 421 | /* keys that don't match */ |
| 422 | if (!match(key, description)) |
| 423 | continue; |
| 424 | |
| 425 | /* key must have search permissions */ |
| 426 | if (key_task_permission(make_key_ref(key, possessed), |
| 427 | cred, KEY_SEARCH) < 0) |
| 428 | continue; |
| 429 | |
| 430 | if (no_state_check) |
| 431 | goto found; |
| 432 | |
| 433 | /* we set a different error code if we pass a negative key */ |
| 434 | if (kflags & (1 << KEY_FLAG_NEGATIVE)) { |
| 435 | err = key->type_data.reject_error; |
| 436 | continue; |
| 437 | } |
| 438 | |
| 439 | goto found; |
| 440 | } |
| 441 | |
| 442 | /* search through the keyrings nested in this one */ |
| 443 | kix = 0; |
| 444 | ascend: |
| 445 | nkeys = keylist->nkeys; |
| 446 | smp_rmb(); |
| 447 | for (; kix < nkeys; kix++) { |
| 448 | key = rcu_dereference(keylist->keys[kix]); |
| 449 | if (key->type != &key_type_keyring) |
| 450 | continue; |
| 451 | |
| 452 | /* recursively search nested keyrings |
| 453 | * - only search keyrings for which we have search permission |
| 454 | */ |
| 455 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) |
| 456 | continue; |
| 457 | |
| 458 | if (key_task_permission(make_key_ref(key, possessed), |
| 459 | cred, KEY_SEARCH) < 0) |
| 460 | continue; |
| 461 | |
| 462 | /* stack the current position */ |
| 463 | stack[sp].keyring = keyring; |
| 464 | stack[sp].keylist = keylist; |
| 465 | stack[sp].kix = kix; |
| 466 | sp++; |
| 467 | |
| 468 | /* begin again with the new keyring */ |
| 469 | keyring = key; |
| 470 | goto descend; |
| 471 | } |
| 472 | |
| 473 | /* the keyring we're looking at was disqualified or didn't contain a |
| 474 | * matching key */ |
| 475 | not_this_keyring: |
| 476 | if (sp > 0) { |
| 477 | /* resume the processing of a keyring higher up in the tree */ |
| 478 | sp--; |
| 479 | keyring = stack[sp].keyring; |
| 480 | keylist = stack[sp].keylist; |
| 481 | kix = stack[sp].kix + 1; |
| 482 | goto ascend; |
| 483 | } |
| 484 | |
| 485 | key_ref = ERR_PTR(err); |
| 486 | goto error_2; |
| 487 | |
| 488 | /* we found a viable match */ |
| 489 | found: |
| 490 | atomic_inc(&key->usage); |
| 491 | key->last_used_at = now.tv_sec; |
| 492 | keyring->last_used_at = now.tv_sec; |
| 493 | while (sp > 0) |
| 494 | stack[--sp].keyring->last_used_at = now.tv_sec; |
| 495 | key_check(key); |
| 496 | key_ref = make_key_ref(key, possessed); |
| 497 | error_2: |
| 498 | rcu_read_unlock(); |
| 499 | error: |
| 500 | return key_ref; |
| 501 | } |
| 502 | |
| 503 | /** |
| 504 | * keyring_search - Search the supplied keyring tree for a matching key |
| 505 | * @keyring: The root of the keyring tree to be searched. |
| 506 | * @type: The type of keyring we want to find. |
| 507 | * @description: The name of the keyring we want to find. |
| 508 | * |
| 509 | * As keyring_search_aux() above, but using the current task's credentials and |
| 510 | * type's default matching function. |
| 511 | */ |
| 512 | key_ref_t keyring_search(key_ref_t keyring, |
| 513 | struct key_type *type, |
| 514 | const char *description) |
| 515 | { |
| 516 | if (!type->match) |
| 517 | return ERR_PTR(-ENOKEY); |
| 518 | |
| 519 | return keyring_search_aux(keyring, current->cred, |
| 520 | type, description, type->match, false); |
| 521 | } |
| 522 | EXPORT_SYMBOL(keyring_search); |
| 523 | |
| 524 | /* |
| 525 | * Search the given keyring only (no recursion). |
| 526 | * |
| 527 | * The caller must guarantee that the keyring is a keyring and that the |
| 528 | * permission is granted to search the keyring as no check is made here. |
| 529 | * |
| 530 | * RCU is used to make it unnecessary to lock the keyring key list here. |
| 531 | * |
| 532 | * Returns a pointer to the found key with usage count incremented if |
| 533 | * successful and returns -ENOKEY if not found. Revoked keys and keys not |
| 534 | * providing the requested permission are skipped over. |
| 535 | * |
| 536 | * If successful, the possession indicator is propagated from the keyring ref |
| 537 | * to the returned key reference. |
| 538 | */ |
| 539 | key_ref_t __keyring_search_one(key_ref_t keyring_ref, |
| 540 | const struct key_type *ktype, |
| 541 | const char *description, |
| 542 | key_perm_t perm) |
| 543 | { |
| 544 | struct keyring_list *klist; |
| 545 | unsigned long possessed; |
| 546 | struct key *keyring, *key; |
| 547 | int nkeys, loop; |
| 548 | |
| 549 | keyring = key_ref_to_ptr(keyring_ref); |
| 550 | possessed = is_key_possessed(keyring_ref); |
| 551 | |
| 552 | rcu_read_lock(); |
| 553 | |
| 554 | klist = rcu_dereference(keyring->payload.subscriptions); |
| 555 | if (klist) { |
| 556 | nkeys = klist->nkeys; |
| 557 | smp_rmb(); |
| 558 | for (loop = 0; loop < nkeys ; loop++) { |
| 559 | key = rcu_dereference(klist->keys[loop]); |
| 560 | if (key->type == ktype && |
| 561 | (!key->type->match || |
| 562 | key->type->match(key, description)) && |
| 563 | key_permission(make_key_ref(key, possessed), |
| 564 | perm) == 0 && |
| 565 | !(key->flags & ((1 << KEY_FLAG_INVALIDATED) | |
| 566 | (1 << KEY_FLAG_REVOKED))) |
| 567 | ) |
| 568 | goto found; |
| 569 | } |
| 570 | } |
| 571 | |
| 572 | rcu_read_unlock(); |
| 573 | return ERR_PTR(-ENOKEY); |
| 574 | |
| 575 | found: |
| 576 | atomic_inc(&key->usage); |
| 577 | keyring->last_used_at = key->last_used_at = |
| 578 | current_kernel_time().tv_sec; |
| 579 | rcu_read_unlock(); |
| 580 | return make_key_ref(key, possessed); |
| 581 | } |
| 582 | |
| 583 | /* |
| 584 | * Find a keyring with the specified name. |
| 585 | * |
| 586 | * Only keyrings that have nonzero refcount, are not revoked, and are owned by a |
| 587 | * user in the current user namespace are considered. If @uid_keyring is %true, |
| 588 | * the keyring additionally must have been allocated as a user or user session |
| 589 | * keyring; otherwise, it must grant Search permission directly to the caller. |
| 590 | * |
| 591 | * Returns a pointer to the keyring with the keyring's refcount having being |
| 592 | * incremented on success. -ENOKEY is returned if a key could not be found. |
| 593 | */ |
| 594 | struct key *find_keyring_by_name(const char *name, bool uid_keyring) |
| 595 | { |
| 596 | struct key *keyring; |
| 597 | int bucket; |
| 598 | |
| 599 | if (!name) |
| 600 | return ERR_PTR(-EINVAL); |
| 601 | |
| 602 | bucket = keyring_hash(name); |
| 603 | |
| 604 | read_lock(&keyring_name_lock); |
| 605 | |
| 606 | if (keyring_name_hash[bucket].next) { |
| 607 | /* search this hash bucket for a keyring with a matching name |
| 608 | * that's readable and that hasn't been revoked */ |
| 609 | list_for_each_entry(keyring, |
| 610 | &keyring_name_hash[bucket], |
| 611 | type_data.link |
| 612 | ) { |
| 613 | if (!kuid_has_mapping(current_user_ns(), keyring->user->uid)) |
| 614 | continue; |
| 615 | |
| 616 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
| 617 | continue; |
| 618 | |
| 619 | if (strcmp(keyring->description, name) != 0) |
| 620 | continue; |
| 621 | |
| 622 | if (uid_keyring) { |
| 623 | if (!test_bit(KEY_FLAG_UID_KEYRING, |
| 624 | &keyring->flags)) |
| 625 | continue; |
| 626 | } else { |
| 627 | if (key_permission(make_key_ref(keyring, 0), |
| 628 | KEY_SEARCH) < 0) |
| 629 | continue; |
| 630 | } |
| 631 | |
| 632 | /* we've got a match but we might end up racing with |
| 633 | * key_cleanup() if the keyring is currently 'dead' |
| 634 | * (ie. it has a zero usage count) */ |
| 635 | if (!atomic_inc_not_zero(&keyring->usage)) |
| 636 | continue; |
| 637 | keyring->last_used_at = current_kernel_time().tv_sec; |
| 638 | goto out; |
| 639 | } |
| 640 | } |
| 641 | |
| 642 | keyring = ERR_PTR(-ENOKEY); |
| 643 | out: |
| 644 | read_unlock(&keyring_name_lock); |
| 645 | return keyring; |
| 646 | } |
| 647 | |
| 648 | /* |
| 649 | * See if a cycle will will be created by inserting acyclic tree B in acyclic |
| 650 | * tree A at the topmost level (ie: as a direct child of A). |
| 651 | * |
| 652 | * Since we are adding B to A at the top level, checking for cycles should just |
| 653 | * be a matter of seeing if node A is somewhere in tree B. |
| 654 | */ |
| 655 | static int keyring_detect_cycle(struct key *A, struct key *B) |
| 656 | { |
| 657 | struct { |
| 658 | struct keyring_list *keylist; |
| 659 | int kix; |
| 660 | } stack[KEYRING_SEARCH_MAX_DEPTH]; |
| 661 | |
| 662 | struct keyring_list *keylist; |
| 663 | struct key *subtree, *key; |
| 664 | int sp, nkeys, kix, ret; |
| 665 | |
| 666 | rcu_read_lock(); |
| 667 | |
| 668 | ret = -EDEADLK; |
| 669 | if (A == B) |
| 670 | goto cycle_detected; |
| 671 | |
| 672 | subtree = B; |
| 673 | sp = 0; |
| 674 | |
| 675 | /* start processing a new keyring */ |
| 676 | descend: |
| 677 | if (test_bit(KEY_FLAG_REVOKED, &subtree->flags)) |
| 678 | goto not_this_keyring; |
| 679 | |
| 680 | keylist = rcu_dereference(subtree->payload.subscriptions); |
| 681 | if (!keylist) |
| 682 | goto not_this_keyring; |
| 683 | kix = 0; |
| 684 | |
| 685 | ascend: |
| 686 | /* iterate through the remaining keys in this keyring */ |
| 687 | nkeys = keylist->nkeys; |
| 688 | smp_rmb(); |
| 689 | for (; kix < nkeys; kix++) { |
| 690 | key = rcu_dereference(keylist->keys[kix]); |
| 691 | |
| 692 | if (key == A) |
| 693 | goto cycle_detected; |
| 694 | |
| 695 | /* recursively check nested keyrings */ |
| 696 | if (key->type == &key_type_keyring) { |
| 697 | if (sp >= KEYRING_SEARCH_MAX_DEPTH) |
| 698 | goto too_deep; |
| 699 | |
| 700 | /* stack the current position */ |
| 701 | stack[sp].keylist = keylist; |
| 702 | stack[sp].kix = kix; |
| 703 | sp++; |
| 704 | |
| 705 | /* begin again with the new keyring */ |
| 706 | subtree = key; |
| 707 | goto descend; |
| 708 | } |
| 709 | } |
| 710 | |
| 711 | /* the keyring we're looking at was disqualified or didn't contain a |
| 712 | * matching key */ |
| 713 | not_this_keyring: |
| 714 | if (sp > 0) { |
| 715 | /* resume the checking of a keyring higher up in the tree */ |
| 716 | sp--; |
| 717 | keylist = stack[sp].keylist; |
| 718 | kix = stack[sp].kix + 1; |
| 719 | goto ascend; |
| 720 | } |
| 721 | |
| 722 | ret = 0; /* no cycles detected */ |
| 723 | |
| 724 | error: |
| 725 | rcu_read_unlock(); |
| 726 | return ret; |
| 727 | |
| 728 | too_deep: |
| 729 | ret = -ELOOP; |
| 730 | goto error; |
| 731 | |
| 732 | cycle_detected: |
| 733 | ret = -EDEADLK; |
| 734 | goto error; |
| 735 | } |
| 736 | |
| 737 | /* |
| 738 | * Dispose of a keyring list after the RCU grace period, freeing the unlinked |
| 739 | * key |
| 740 | */ |
| 741 | static void keyring_unlink_rcu_disposal(struct rcu_head *rcu) |
| 742 | { |
| 743 | struct keyring_list *klist = |
| 744 | container_of(rcu, struct keyring_list, rcu); |
| 745 | |
| 746 | if (klist->delkey != USHRT_MAX) |
| 747 | key_put(rcu_access_pointer(klist->keys[klist->delkey])); |
| 748 | kfree(klist); |
| 749 | } |
| 750 | |
| 751 | /* |
| 752 | * Preallocate memory so that a key can be linked into to a keyring. |
| 753 | */ |
| 754 | int __key_link_begin(struct key *keyring, const struct key_type *type, |
| 755 | const char *description, unsigned long *_prealloc) |
| 756 | __acquires(&keyring->sem) |
| 757 | __acquires(&keyring_serialise_link_sem) |
| 758 | { |
| 759 | struct keyring_list *klist, *nklist; |
| 760 | unsigned long prealloc; |
| 761 | unsigned max; |
| 762 | time_t lowest_lru; |
| 763 | size_t size; |
| 764 | int loop, lru, ret; |
| 765 | |
| 766 | kenter("%d,%s,%s,", key_serial(keyring), type->name, description); |
| 767 | |
| 768 | if (keyring->type != &key_type_keyring) |
| 769 | return -ENOTDIR; |
| 770 | |
| 771 | down_write(&keyring->sem); |
| 772 | |
| 773 | ret = -EKEYREVOKED; |
| 774 | if (test_bit(KEY_FLAG_REVOKED, &keyring->flags)) |
| 775 | goto error_krsem; |
| 776 | |
| 777 | /* serialise link/link calls to prevent parallel calls causing a cycle |
| 778 | * when linking two keyring in opposite orders */ |
| 779 | if (type == &key_type_keyring) |
| 780 | down_write(&keyring_serialise_link_sem); |
| 781 | |
| 782 | klist = rcu_dereference_locked_keyring(keyring); |
| 783 | |
| 784 | /* see if there's a matching key we can displace */ |
| 785 | lru = -1; |
| 786 | if (klist && klist->nkeys > 0) { |
| 787 | lowest_lru = TIME_T_MAX; |
| 788 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { |
| 789 | struct key *key = rcu_deref_link_locked(klist, loop, |
| 790 | keyring); |
| 791 | if (key->type == type && |
| 792 | strcmp(key->description, description) == 0) { |
| 793 | /* Found a match - we'll replace the link with |
| 794 | * one to the new key. We record the slot |
| 795 | * position. |
| 796 | */ |
| 797 | klist->delkey = loop; |
| 798 | prealloc = 0; |
| 799 | goto done; |
| 800 | } |
| 801 | if (key->last_used_at < lowest_lru) { |
| 802 | lowest_lru = key->last_used_at; |
| 803 | lru = loop; |
| 804 | } |
| 805 | } |
| 806 | } |
| 807 | |
| 808 | /* If the keyring is full then do an LRU discard */ |
| 809 | if (klist && |
| 810 | klist->nkeys == klist->maxkeys && |
| 811 | klist->maxkeys >= MAX_KEYRING_LINKS) { |
| 812 | kdebug("LRU discard %d\n", lru); |
| 813 | klist->delkey = lru; |
| 814 | prealloc = 0; |
| 815 | goto done; |
| 816 | } |
| 817 | |
| 818 | /* check that we aren't going to overrun the user's quota */ |
| 819 | ret = key_payload_reserve(keyring, |
| 820 | keyring->datalen + KEYQUOTA_LINK_BYTES); |
| 821 | if (ret < 0) |
| 822 | goto error_sem; |
| 823 | |
| 824 | if (klist && klist->nkeys < klist->maxkeys) { |
| 825 | /* there's sufficient slack space to append directly */ |
| 826 | klist->delkey = klist->nkeys; |
| 827 | prealloc = KEY_LINK_FIXQUOTA; |
| 828 | } else { |
| 829 | /* grow the key list */ |
| 830 | max = 4; |
| 831 | if (klist) { |
| 832 | max += klist->maxkeys; |
| 833 | if (max > MAX_KEYRING_LINKS) |
| 834 | max = MAX_KEYRING_LINKS; |
| 835 | BUG_ON(max <= klist->maxkeys); |
| 836 | } |
| 837 | |
| 838 | size = sizeof(*klist) + sizeof(struct key *) * max; |
| 839 | |
| 840 | ret = -ENOMEM; |
| 841 | nklist = kmalloc(size, GFP_KERNEL); |
| 842 | if (!nklist) |
| 843 | goto error_quota; |
| 844 | |
| 845 | nklist->maxkeys = max; |
| 846 | if (klist) { |
| 847 | memcpy(nklist->keys, klist->keys, |
| 848 | sizeof(struct key *) * klist->nkeys); |
| 849 | nklist->delkey = klist->nkeys; |
| 850 | nklist->nkeys = klist->nkeys + 1; |
| 851 | klist->delkey = USHRT_MAX; |
| 852 | } else { |
| 853 | nklist->nkeys = 1; |
| 854 | nklist->delkey = 0; |
| 855 | } |
| 856 | |
| 857 | /* add the key into the new space */ |
| 858 | RCU_INIT_POINTER(nklist->keys[nklist->delkey], NULL); |
| 859 | prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA; |
| 860 | } |
| 861 | |
| 862 | done: |
| 863 | *_prealloc = prealloc; |
| 864 | kleave(" = 0"); |
| 865 | return 0; |
| 866 | |
| 867 | error_quota: |
| 868 | /* undo the quota changes */ |
| 869 | key_payload_reserve(keyring, |
| 870 | keyring->datalen - KEYQUOTA_LINK_BYTES); |
| 871 | error_sem: |
| 872 | if (type == &key_type_keyring) |
| 873 | up_write(&keyring_serialise_link_sem); |
| 874 | error_krsem: |
| 875 | up_write(&keyring->sem); |
| 876 | kleave(" = %d", ret); |
| 877 | return ret; |
| 878 | } |
| 879 | |
| 880 | /* |
| 881 | * Check already instantiated keys aren't going to be a problem. |
| 882 | * |
| 883 | * The caller must have called __key_link_begin(). Don't need to call this for |
| 884 | * keys that were created since __key_link_begin() was called. |
| 885 | */ |
| 886 | int __key_link_check_live_key(struct key *keyring, struct key *key) |
| 887 | { |
| 888 | if (key->type == &key_type_keyring) |
| 889 | /* check that we aren't going to create a cycle by linking one |
| 890 | * keyring to another */ |
| 891 | return keyring_detect_cycle(keyring, key); |
| 892 | return 0; |
| 893 | } |
| 894 | |
| 895 | /* |
| 896 | * Link a key into to a keyring. |
| 897 | * |
| 898 | * Must be called with __key_link_begin() having being called. Discards any |
| 899 | * already extant link to matching key if there is one, so that each keyring |
| 900 | * holds at most one link to any given key of a particular type+description |
| 901 | * combination. |
| 902 | */ |
| 903 | void __key_link(struct key *keyring, struct key *key, |
| 904 | unsigned long *_prealloc) |
| 905 | { |
| 906 | struct keyring_list *klist, *nklist; |
| 907 | struct key *discard; |
| 908 | |
| 909 | nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA); |
| 910 | *_prealloc = 0; |
| 911 | |
| 912 | kenter("%d,%d,%p", keyring->serial, key->serial, nklist); |
| 913 | |
| 914 | klist = rcu_dereference_locked_keyring(keyring); |
| 915 | |
| 916 | atomic_inc(&key->usage); |
| 917 | keyring->last_used_at = key->last_used_at = |
| 918 | current_kernel_time().tv_sec; |
| 919 | |
| 920 | /* there's a matching key we can displace or an empty slot in a newly |
| 921 | * allocated list we can fill */ |
| 922 | if (nklist) { |
| 923 | kdebug("reissue %hu/%hu/%hu", |
| 924 | nklist->delkey, nklist->nkeys, nklist->maxkeys); |
| 925 | |
| 926 | RCU_INIT_POINTER(nklist->keys[nklist->delkey], key); |
| 927 | |
| 928 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); |
| 929 | |
| 930 | /* dispose of the old keyring list and, if there was one, the |
| 931 | * displaced key */ |
| 932 | if (klist) { |
| 933 | kdebug("dispose %hu/%hu/%hu", |
| 934 | klist->delkey, klist->nkeys, klist->maxkeys); |
| 935 | call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); |
| 936 | } |
| 937 | } else if (klist->delkey < klist->nkeys) { |
| 938 | kdebug("replace %hu/%hu/%hu", |
| 939 | klist->delkey, klist->nkeys, klist->maxkeys); |
| 940 | |
| 941 | discard = rcu_dereference_protected( |
| 942 | klist->keys[klist->delkey], |
| 943 | rwsem_is_locked(&keyring->sem)); |
| 944 | rcu_assign_pointer(klist->keys[klist->delkey], key); |
| 945 | /* The garbage collector will take care of RCU |
| 946 | * synchronisation */ |
| 947 | key_put(discard); |
| 948 | } else { |
| 949 | /* there's sufficient slack space to append directly */ |
| 950 | kdebug("append %hu/%hu/%hu", |
| 951 | klist->delkey, klist->nkeys, klist->maxkeys); |
| 952 | |
| 953 | RCU_INIT_POINTER(klist->keys[klist->delkey], key); |
| 954 | smp_wmb(); |
| 955 | klist->nkeys++; |
| 956 | } |
| 957 | } |
| 958 | |
| 959 | /* |
| 960 | * Finish linking a key into to a keyring. |
| 961 | * |
| 962 | * Must be called with __key_link_begin() having being called. |
| 963 | */ |
| 964 | void __key_link_end(struct key *keyring, struct key_type *type, |
| 965 | unsigned long prealloc) |
| 966 | __releases(&keyring->sem) |
| 967 | __releases(&keyring_serialise_link_sem) |
| 968 | { |
| 969 | BUG_ON(type == NULL); |
| 970 | BUG_ON(type->name == NULL); |
| 971 | kenter("%d,%s,%lx", keyring->serial, type->name, prealloc); |
| 972 | |
| 973 | if (type == &key_type_keyring) |
| 974 | up_write(&keyring_serialise_link_sem); |
| 975 | |
| 976 | if (prealloc) { |
| 977 | if (prealloc & KEY_LINK_FIXQUOTA) |
| 978 | key_payload_reserve(keyring, |
| 979 | keyring->datalen - |
| 980 | KEYQUOTA_LINK_BYTES); |
| 981 | kfree((struct keyring_list *)(prealloc & ~KEY_LINK_FIXQUOTA)); |
| 982 | } |
| 983 | up_write(&keyring->sem); |
| 984 | } |
| 985 | |
| 986 | /** |
| 987 | * key_link - Link a key to a keyring |
| 988 | * @keyring: The keyring to make the link in. |
| 989 | * @key: The key to link to. |
| 990 | * |
| 991 | * Make a link in a keyring to a key, such that the keyring holds a reference |
| 992 | * on that key and the key can potentially be found by searching that keyring. |
| 993 | * |
| 994 | * This function will write-lock the keyring's semaphore and will consume some |
| 995 | * of the user's key data quota to hold the link. |
| 996 | * |
| 997 | * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, |
| 998 | * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is |
| 999 | * full, -EDQUOT if there is insufficient key data quota remaining to add |
| 1000 | * another link or -ENOMEM if there's insufficient memory. |
| 1001 | * |
| 1002 | * It is assumed that the caller has checked that it is permitted for a link to |
| 1003 | * be made (the keyring should have Write permission and the key Link |
| 1004 | * permission). |
| 1005 | */ |
| 1006 | int key_link(struct key *keyring, struct key *key) |
| 1007 | { |
| 1008 | unsigned long prealloc; |
| 1009 | int ret; |
| 1010 | |
| 1011 | key_check(keyring); |
| 1012 | key_check(key); |
| 1013 | |
| 1014 | ret = __key_link_begin(keyring, key->type, key->description, &prealloc); |
| 1015 | if (ret == 0) { |
| 1016 | ret = __key_link_check_live_key(keyring, key); |
| 1017 | if (ret == 0) |
| 1018 | __key_link(keyring, key, &prealloc); |
| 1019 | __key_link_end(keyring, key->type, prealloc); |
| 1020 | } |
| 1021 | |
| 1022 | return ret; |
| 1023 | } |
| 1024 | EXPORT_SYMBOL(key_link); |
| 1025 | |
| 1026 | /** |
| 1027 | * key_unlink - Unlink the first link to a key from a keyring. |
| 1028 | * @keyring: The keyring to remove the link from. |
| 1029 | * @key: The key the link is to. |
| 1030 | * |
| 1031 | * Remove a link from a keyring to a key. |
| 1032 | * |
| 1033 | * This function will write-lock the keyring's semaphore. |
| 1034 | * |
| 1035 | * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if |
| 1036 | * the key isn't linked to by the keyring or -ENOMEM if there's insufficient |
| 1037 | * memory. |
| 1038 | * |
| 1039 | * It is assumed that the caller has checked that it is permitted for a link to |
| 1040 | * be removed (the keyring should have Write permission; no permissions are |
| 1041 | * required on the key). |
| 1042 | */ |
| 1043 | int key_unlink(struct key *keyring, struct key *key) |
| 1044 | { |
| 1045 | struct keyring_list *klist, *nklist; |
| 1046 | int loop, ret; |
| 1047 | |
| 1048 | key_check(keyring); |
| 1049 | key_check(key); |
| 1050 | |
| 1051 | ret = -ENOTDIR; |
| 1052 | if (keyring->type != &key_type_keyring) |
| 1053 | goto error; |
| 1054 | |
| 1055 | down_write(&keyring->sem); |
| 1056 | |
| 1057 | klist = rcu_dereference_locked_keyring(keyring); |
| 1058 | if (klist) { |
| 1059 | /* search the keyring for the key */ |
| 1060 | for (loop = 0; loop < klist->nkeys; loop++) |
| 1061 | if (rcu_access_pointer(klist->keys[loop]) == key) |
| 1062 | goto key_is_present; |
| 1063 | } |
| 1064 | |
| 1065 | up_write(&keyring->sem); |
| 1066 | ret = -ENOENT; |
| 1067 | goto error; |
| 1068 | |
| 1069 | key_is_present: |
| 1070 | /* we need to copy the key list for RCU purposes */ |
| 1071 | nklist = kmalloc(sizeof(*klist) + |
| 1072 | sizeof(struct key *) * klist->maxkeys, |
| 1073 | GFP_KERNEL); |
| 1074 | if (!nklist) |
| 1075 | goto nomem; |
| 1076 | nklist->maxkeys = klist->maxkeys; |
| 1077 | nklist->nkeys = klist->nkeys - 1; |
| 1078 | |
| 1079 | if (loop > 0) |
| 1080 | memcpy(&nklist->keys[0], |
| 1081 | &klist->keys[0], |
| 1082 | loop * sizeof(struct key *)); |
| 1083 | |
| 1084 | if (loop < nklist->nkeys) |
| 1085 | memcpy(&nklist->keys[loop], |
| 1086 | &klist->keys[loop + 1], |
| 1087 | (nklist->nkeys - loop) * sizeof(struct key *)); |
| 1088 | |
| 1089 | /* adjust the user's quota */ |
| 1090 | key_payload_reserve(keyring, |
| 1091 | keyring->datalen - KEYQUOTA_LINK_BYTES); |
| 1092 | |
| 1093 | rcu_assign_pointer(keyring->payload.subscriptions, nklist); |
| 1094 | |
| 1095 | up_write(&keyring->sem); |
| 1096 | |
| 1097 | /* schedule for later cleanup */ |
| 1098 | klist->delkey = loop; |
| 1099 | call_rcu(&klist->rcu, keyring_unlink_rcu_disposal); |
| 1100 | |
| 1101 | ret = 0; |
| 1102 | |
| 1103 | error: |
| 1104 | return ret; |
| 1105 | nomem: |
| 1106 | ret = -ENOMEM; |
| 1107 | up_write(&keyring->sem); |
| 1108 | goto error; |
| 1109 | } |
| 1110 | EXPORT_SYMBOL(key_unlink); |
| 1111 | |
| 1112 | /* |
| 1113 | * Dispose of a keyring list after the RCU grace period, releasing the keys it |
| 1114 | * links to. |
| 1115 | */ |
| 1116 | static void keyring_clear_rcu_disposal(struct rcu_head *rcu) |
| 1117 | { |
| 1118 | struct keyring_list *klist; |
| 1119 | int loop; |
| 1120 | |
| 1121 | klist = container_of(rcu, struct keyring_list, rcu); |
| 1122 | |
| 1123 | for (loop = klist->nkeys - 1; loop >= 0; loop--) |
| 1124 | key_put(rcu_access_pointer(klist->keys[loop])); |
| 1125 | |
| 1126 | kfree(klist); |
| 1127 | } |
| 1128 | |
| 1129 | /** |
| 1130 | * keyring_clear - Clear a keyring |
| 1131 | * @keyring: The keyring to clear. |
| 1132 | * |
| 1133 | * Clear the contents of the specified keyring. |
| 1134 | * |
| 1135 | * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring. |
| 1136 | */ |
| 1137 | int keyring_clear(struct key *keyring) |
| 1138 | { |
| 1139 | struct keyring_list *klist; |
| 1140 | int ret; |
| 1141 | |
| 1142 | ret = -ENOTDIR; |
| 1143 | if (keyring->type == &key_type_keyring) { |
| 1144 | /* detach the pointer block with the locks held */ |
| 1145 | down_write(&keyring->sem); |
| 1146 | |
| 1147 | klist = rcu_dereference_locked_keyring(keyring); |
| 1148 | if (klist) { |
| 1149 | /* adjust the quota */ |
| 1150 | key_payload_reserve(keyring, |
| 1151 | sizeof(struct keyring_list)); |
| 1152 | |
| 1153 | rcu_assign_pointer(keyring->payload.subscriptions, |
| 1154 | NULL); |
| 1155 | } |
| 1156 | |
| 1157 | up_write(&keyring->sem); |
| 1158 | |
| 1159 | /* free the keys after the locks have been dropped */ |
| 1160 | if (klist) |
| 1161 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); |
| 1162 | |
| 1163 | ret = 0; |
| 1164 | } |
| 1165 | |
| 1166 | return ret; |
| 1167 | } |
| 1168 | EXPORT_SYMBOL(keyring_clear); |
| 1169 | |
| 1170 | /* |
| 1171 | * Dispose of the links from a revoked keyring. |
| 1172 | * |
| 1173 | * This is called with the key sem write-locked. |
| 1174 | */ |
| 1175 | static void keyring_revoke(struct key *keyring) |
| 1176 | { |
| 1177 | struct keyring_list *klist; |
| 1178 | |
| 1179 | klist = rcu_dereference_locked_keyring(keyring); |
| 1180 | |
| 1181 | /* adjust the quota */ |
| 1182 | key_payload_reserve(keyring, 0); |
| 1183 | |
| 1184 | if (klist) { |
| 1185 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); |
| 1186 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); |
| 1187 | } |
| 1188 | } |
| 1189 | |
| 1190 | /* |
| 1191 | * Collect garbage from the contents of a keyring, replacing the old list with |
| 1192 | * a new one with the pointers all shuffled down. |
| 1193 | * |
| 1194 | * Dead keys are classed as oned that are flagged as being dead or are revoked, |
| 1195 | * expired or negative keys that were revoked or expired before the specified |
| 1196 | * limit. |
| 1197 | */ |
| 1198 | void keyring_gc(struct key *keyring, time_t limit) |
| 1199 | { |
| 1200 | struct keyring_list *klist, *new; |
| 1201 | struct key *key; |
| 1202 | int loop, keep, max; |
| 1203 | |
| 1204 | kenter("{%x,%s}", key_serial(keyring), keyring->description); |
| 1205 | |
| 1206 | down_write(&keyring->sem); |
| 1207 | |
| 1208 | klist = rcu_dereference_locked_keyring(keyring); |
| 1209 | if (!klist) |
| 1210 | goto no_klist; |
| 1211 | |
| 1212 | /* work out how many subscriptions we're keeping */ |
| 1213 | keep = 0; |
| 1214 | for (loop = klist->nkeys - 1; loop >= 0; loop--) |
| 1215 | if (!key_is_dead(rcu_deref_link_locked(klist, loop, keyring), |
| 1216 | limit)) |
| 1217 | keep++; |
| 1218 | |
| 1219 | if (keep == klist->nkeys) |
| 1220 | goto just_return; |
| 1221 | |
| 1222 | /* allocate a new keyring payload */ |
| 1223 | max = roundup(keep, 4); |
| 1224 | new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *), |
| 1225 | GFP_KERNEL); |
| 1226 | if (!new) |
| 1227 | goto nomem; |
| 1228 | new->maxkeys = max; |
| 1229 | new->nkeys = 0; |
| 1230 | new->delkey = 0; |
| 1231 | |
| 1232 | /* install the live keys |
| 1233 | * - must take care as expired keys may be updated back to life |
| 1234 | */ |
| 1235 | keep = 0; |
| 1236 | for (loop = klist->nkeys - 1; loop >= 0; loop--) { |
| 1237 | key = rcu_deref_link_locked(klist, loop, keyring); |
| 1238 | if (!key_is_dead(key, limit)) { |
| 1239 | if (keep >= max) |
| 1240 | goto discard_new; |
| 1241 | RCU_INIT_POINTER(new->keys[keep++], key_get(key)); |
| 1242 | } |
| 1243 | } |
| 1244 | new->nkeys = keep; |
| 1245 | |
| 1246 | /* adjust the quota */ |
| 1247 | key_payload_reserve(keyring, |
| 1248 | sizeof(struct keyring_list) + |
| 1249 | KEYQUOTA_LINK_BYTES * keep); |
| 1250 | |
| 1251 | if (keep == 0) { |
| 1252 | rcu_assign_pointer(keyring->payload.subscriptions, NULL); |
| 1253 | kfree(new); |
| 1254 | } else { |
| 1255 | rcu_assign_pointer(keyring->payload.subscriptions, new); |
| 1256 | } |
| 1257 | |
| 1258 | up_write(&keyring->sem); |
| 1259 | |
| 1260 | call_rcu(&klist->rcu, keyring_clear_rcu_disposal); |
| 1261 | kleave(" [yes]"); |
| 1262 | return; |
| 1263 | |
| 1264 | discard_new: |
| 1265 | new->nkeys = keep; |
| 1266 | keyring_clear_rcu_disposal(&new->rcu); |
| 1267 | up_write(&keyring->sem); |
| 1268 | kleave(" [discard]"); |
| 1269 | return; |
| 1270 | |
| 1271 | just_return: |
| 1272 | up_write(&keyring->sem); |
| 1273 | kleave(" [no dead]"); |
| 1274 | return; |
| 1275 | |
| 1276 | no_klist: |
| 1277 | up_write(&keyring->sem); |
| 1278 | kleave(" [no_klist]"); |
| 1279 | return; |
| 1280 | |
| 1281 | nomem: |
| 1282 | up_write(&keyring->sem); |
| 1283 | kleave(" [oom]"); |
| 1284 | } |