1 /* Basic authentication token and access key management 2 * 3 * Copyright (C) 2004-2008 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/poison.h> 15 #include <linux/sched.h> 16 #include <linux/slab.h> 17 #include <linux/security.h> 18 #include <linux/workqueue.h> 19 #include <linux/random.h> 20 #include <linux/err.h> 21 #include "internal.h" 22 23 struct kmem_cache *key_jar; 24 struct rb_root key_serial_tree; /* tree of keys indexed by serial */ 25 DEFINE_SPINLOCK(key_serial_lock); 26 27 struct rb_root key_user_tree; /* tree of quota records indexed by UID */ 28 DEFINE_SPINLOCK(key_user_lock); 29 30 unsigned int key_quota_root_maxkeys = 1000000; /* root's key count quota */ 31 unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */ 32 unsigned int key_quota_maxkeys = 200; /* general key count quota */ 33 unsigned int key_quota_maxbytes = 20000; /* general key space quota */ 34 35 static LIST_HEAD(key_types_list); 36 static DECLARE_RWSEM(key_types_sem); 37 38 /* We serialise key instantiation and link */ 39 DEFINE_MUTEX(key_construction_mutex); 40 41 #ifdef KEY_DEBUGGING 42 void __key_check(const struct key *key) 43 { 44 printk("__key_check: key %p {%08x} should be {%08x}\n", 45 key, key->magic, KEY_DEBUG_MAGIC); 46 BUG(); 47 } 48 #endif 49 50 /* 51 * Get the key quota record for a user, allocating a new record if one doesn't 52 * already exist. 53 */ 54 struct key_user *key_user_lookup(kuid_t uid) 55 { 56 struct key_user *candidate = NULL, *user; 57 struct rb_node *parent = NULL; 58 struct rb_node **p; 59 60 try_again: 61 p = &key_user_tree.rb_node; 62 spin_lock(&key_user_lock); 63 64 /* search the tree for a user record with a matching UID */ 65 while (*p) { 66 parent = *p; 67 user = rb_entry(parent, struct key_user, node); 68 69 if (uid_lt(uid, user->uid)) 70 p = &(*p)->rb_left; 71 else if (uid_gt(uid, user->uid)) 72 p = &(*p)->rb_right; 73 else 74 goto found; 75 } 76 77 /* if we get here, we failed to find a match in the tree */ 78 if (!candidate) { 79 /* allocate a candidate user record if we don't already have 80 * one */ 81 spin_unlock(&key_user_lock); 82 83 user = NULL; 84 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL); 85 if (unlikely(!candidate)) 86 goto out; 87 88 /* the allocation may have scheduled, so we need to repeat the 89 * search lest someone else added the record whilst we were 90 * asleep */ 91 goto try_again; 92 } 93 94 /* if we get here, then the user record still hadn't appeared on the 95 * second pass - so we use the candidate record */ 96 atomic_set(&candidate->usage, 1); 97 atomic_set(&candidate->nkeys, 0); 98 atomic_set(&candidate->nikeys, 0); 99 candidate->uid = uid; 100 candidate->qnkeys = 0; 101 candidate->qnbytes = 0; 102 spin_lock_init(&candidate->lock); 103 mutex_init(&candidate->cons_lock); 104 105 rb_link_node(&candidate->node, parent, p); 106 rb_insert_color(&candidate->node, &key_user_tree); 107 spin_unlock(&key_user_lock); 108 user = candidate; 109 goto out; 110 111 /* okay - we found a user record for this UID */ 112 found: 113 atomic_inc(&user->usage); 114 spin_unlock(&key_user_lock); 115 kfree(candidate); 116 out: 117 return user; 118 } 119 120 /* 121 * Dispose of a user structure 122 */ 123 void key_user_put(struct key_user *user) 124 { 125 if (atomic_dec_and_lock(&user->usage, &key_user_lock)) { 126 rb_erase(&user->node, &key_user_tree); 127 spin_unlock(&key_user_lock); 128 129 kfree(user); 130 } 131 } 132 133 /* 134 * Allocate a serial number for a key. These are assigned randomly to avoid 135 * security issues through covert channel problems. 136 */ 137 static inline void key_alloc_serial(struct key *key) 138 { 139 struct rb_node *parent, **p; 140 struct key *xkey; 141 142 /* propose a random serial number and look for a hole for it in the 143 * serial number tree */ 144 do { 145 get_random_bytes(&key->serial, sizeof(key->serial)); 146 147 key->serial >>= 1; /* negative numbers are not permitted */ 148 } while (key->serial < 3); 149 150 spin_lock(&key_serial_lock); 151 152 attempt_insertion: 153 parent = NULL; 154 p = &key_serial_tree.rb_node; 155 156 while (*p) { 157 parent = *p; 158 xkey = rb_entry(parent, struct key, serial_node); 159 160 if (key->serial < xkey->serial) 161 p = &(*p)->rb_left; 162 else if (key->serial > xkey->serial) 163 p = &(*p)->rb_right; 164 else 165 goto serial_exists; 166 } 167 168 /* we've found a suitable hole - arrange for this key to occupy it */ 169 rb_link_node(&key->serial_node, parent, p); 170 rb_insert_color(&key->serial_node, &key_serial_tree); 171 172 spin_unlock(&key_serial_lock); 173 return; 174 175 /* we found a key with the proposed serial number - walk the tree from 176 * that point looking for the next unused serial number */ 177 serial_exists: 178 for (;;) { 179 key->serial++; 180 if (key->serial < 3) { 181 key->serial = 3; 182 goto attempt_insertion; 183 } 184 185 parent = rb_next(parent); 186 if (!parent) 187 goto attempt_insertion; 188 189 xkey = rb_entry(parent, struct key, serial_node); 190 if (key->serial < xkey->serial) 191 goto attempt_insertion; 192 } 193 } 194 195 /** 196 * key_alloc - Allocate a key of the specified type. 197 * @type: The type of key to allocate. 198 * @desc: The key description to allow the key to be searched out. 199 * @uid: The owner of the new key. 200 * @gid: The group ID for the new key's group permissions. 201 * @cred: The credentials specifying UID namespace. 202 * @perm: The permissions mask of the new key. 203 * @flags: Flags specifying quota properties. 204 * 205 * Allocate a key of the specified type with the attributes given. The key is 206 * returned in an uninstantiated state and the caller needs to instantiate the 207 * key before returning. 208 * 209 * The user's key count quota is updated to reflect the creation of the key and 210 * the user's key data quota has the default for the key type reserved. The 211 * instantiation function should amend this as necessary. If insufficient 212 * quota is available, -EDQUOT will be returned. 213 * 214 * The LSM security modules can prevent a key being created, in which case 215 * -EACCES will be returned. 216 * 217 * Returns a pointer to the new key if successful and an error code otherwise. 218 * 219 * Note that the caller needs to ensure the key type isn't uninstantiated. 220 * Internally this can be done by locking key_types_sem. Externally, this can 221 * be done by either never unregistering the key type, or making sure 222 * key_alloc() calls don't race with module unloading. 223 */ 224 struct key *key_alloc(struct key_type *type, const char *desc, 225 kuid_t uid, kgid_t gid, const struct cred *cred, 226 key_perm_t perm, unsigned long flags) 227 { 228 struct key_user *user = NULL; 229 struct key *key; 230 size_t desclen, quotalen; 231 int ret; 232 233 key = ERR_PTR(-EINVAL); 234 if (!desc || !*desc) 235 goto error; 236 237 if (type->vet_description) { 238 ret = type->vet_description(desc); 239 if (ret < 0) { 240 key = ERR_PTR(ret); 241 goto error; 242 } 243 } 244 245 desclen = strlen(desc); 246 quotalen = desclen + 1 + type->def_datalen; 247 248 /* get hold of the key tracking for this user */ 249 user = key_user_lookup(uid); 250 if (!user) 251 goto no_memory_1; 252 253 /* check that the user's quota permits allocation of another key and 254 * its description */ 255 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { 256 unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ? 257 key_quota_root_maxkeys : key_quota_maxkeys; 258 unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ? 259 key_quota_root_maxbytes : key_quota_maxbytes; 260 261 spin_lock(&user->lock); 262 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) { 263 if (user->qnkeys + 1 >= maxkeys || 264 user->qnbytes + quotalen >= maxbytes || 265 user->qnbytes + quotalen < user->qnbytes) 266 goto no_quota; 267 } 268 269 user->qnkeys++; 270 user->qnbytes += quotalen; 271 spin_unlock(&user->lock); 272 } 273 274 /* allocate and initialise the key and its description */ 275 key = kmem_cache_zalloc(key_jar, GFP_KERNEL); 276 if (!key) 277 goto no_memory_2; 278 279 key->index_key.desc_len = desclen; 280 key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL); 281 if (!key->index_key.description) 282 goto no_memory_3; 283 284 atomic_set(&key->usage, 1); 285 init_rwsem(&key->sem); 286 lockdep_set_class(&key->sem, &type->lock_class); 287 key->index_key.type = type; 288 key->user = user; 289 key->quotalen = quotalen; 290 key->datalen = type->def_datalen; 291 key->uid = uid; 292 key->gid = gid; 293 key->perm = perm; 294 295 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) 296 key->flags |= 1 << KEY_FLAG_IN_QUOTA; 297 if (flags & KEY_ALLOC_TRUSTED) 298 key->flags |= 1 << KEY_FLAG_TRUSTED; 299 if (flags & KEY_ALLOC_BUILT_IN) 300 key->flags |= 1 << KEY_FLAG_BUILTIN; 301 302 #ifdef KEY_DEBUGGING 303 key->magic = KEY_DEBUG_MAGIC; 304 #endif 305 306 /* let the security module know about the key */ 307 ret = security_key_alloc(key, cred, flags); 308 if (ret < 0) 309 goto security_error; 310 311 /* publish the key by giving it a serial number */ 312 atomic_inc(&user->nkeys); 313 key_alloc_serial(key); 314 315 error: 316 return key; 317 318 security_error: 319 kfree(key->description); 320 kmem_cache_free(key_jar, key); 321 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { 322 spin_lock(&user->lock); 323 user->qnkeys--; 324 user->qnbytes -= quotalen; 325 spin_unlock(&user->lock); 326 } 327 key_user_put(user); 328 key = ERR_PTR(ret); 329 goto error; 330 331 no_memory_3: 332 kmem_cache_free(key_jar, key); 333 no_memory_2: 334 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { 335 spin_lock(&user->lock); 336 user->qnkeys--; 337 user->qnbytes -= quotalen; 338 spin_unlock(&user->lock); 339 } 340 key_user_put(user); 341 no_memory_1: 342 key = ERR_PTR(-ENOMEM); 343 goto error; 344 345 no_quota: 346 spin_unlock(&user->lock); 347 key_user_put(user); 348 key = ERR_PTR(-EDQUOT); 349 goto error; 350 } 351 EXPORT_SYMBOL(key_alloc); 352 353 /** 354 * key_payload_reserve - Adjust data quota reservation for the key's payload 355 * @key: The key to make the reservation for. 356 * @datalen: The amount of data payload the caller now wants. 357 * 358 * Adjust the amount of the owning user's key data quota that a key reserves. 359 * If the amount is increased, then -EDQUOT may be returned if there isn't 360 * enough free quota available. 361 * 362 * If successful, 0 is returned. 363 */ 364 int key_payload_reserve(struct key *key, size_t datalen) 365 { 366 int delta = (int)datalen - key->datalen; 367 int ret = 0; 368 369 key_check(key); 370 371 /* contemplate the quota adjustment */ 372 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) { 373 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ? 374 key_quota_root_maxbytes : key_quota_maxbytes; 375 376 spin_lock(&key->user->lock); 377 378 if (delta > 0 && 379 (key->user->qnbytes + delta >= maxbytes || 380 key->user->qnbytes + delta < key->user->qnbytes)) { 381 ret = -EDQUOT; 382 } 383 else { 384 key->user->qnbytes += delta; 385 key->quotalen += delta; 386 } 387 spin_unlock(&key->user->lock); 388 } 389 390 /* change the recorded data length if that didn't generate an error */ 391 if (ret == 0) 392 key->datalen = datalen; 393 394 return ret; 395 } 396 EXPORT_SYMBOL(key_payload_reserve); 397 398 /* 399 * Instantiate a key and link it into the target keyring atomically. Must be 400 * called with the target keyring's semaphore writelocked. The target key's 401 * semaphore need not be locked as instantiation is serialised by 402 * key_construction_mutex. 403 */ 404 static int __key_instantiate_and_link(struct key *key, 405 struct key_preparsed_payload *prep, 406 struct key *keyring, 407 struct key *authkey, 408 struct assoc_array_edit **_edit) 409 { 410 int ret, awaken; 411 412 key_check(key); 413 key_check(keyring); 414 415 awaken = 0; 416 ret = -EBUSY; 417 418 mutex_lock(&key_construction_mutex); 419 420 /* can't instantiate twice */ 421 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { 422 /* instantiate the key */ 423 ret = key->type->instantiate(key, prep); 424 425 if (ret == 0) { 426 /* mark the key as being instantiated */ 427 atomic_inc(&key->user->nikeys); 428 set_bit(KEY_FLAG_INSTANTIATED, &key->flags); 429 430 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) 431 awaken = 1; 432 433 /* and link it into the destination keyring */ 434 if (keyring) { 435 if (test_bit(KEY_FLAG_KEEP, &keyring->flags)) 436 set_bit(KEY_FLAG_KEEP, &key->flags); 437 438 __key_link(key, _edit); 439 } 440 441 /* disable the authorisation key */ 442 if (authkey) 443 key_revoke(authkey); 444 445 if (prep->expiry != TIME_T_MAX) { 446 key->expiry = prep->expiry; 447 key_schedule_gc(prep->expiry + key_gc_delay); 448 } 449 } 450 } 451 452 mutex_unlock(&key_construction_mutex); 453 454 /* wake up anyone waiting for a key to be constructed */ 455 if (awaken) 456 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); 457 458 return ret; 459 } 460 461 /** 462 * key_instantiate_and_link - Instantiate a key and link it into the keyring. 463 * @key: The key to instantiate. 464 * @data: The data to use to instantiate the keyring. 465 * @datalen: The length of @data. 466 * @keyring: Keyring to create a link in on success (or NULL). 467 * @authkey: The authorisation token permitting instantiation. 468 * 469 * Instantiate a key that's in the uninstantiated state using the provided data 470 * and, if successful, link it in to the destination keyring if one is 471 * supplied. 472 * 473 * If successful, 0 is returned, the authorisation token is revoked and anyone 474 * waiting for the key is woken up. If the key was already instantiated, 475 * -EBUSY will be returned. 476 */ 477 int key_instantiate_and_link(struct key *key, 478 const void *data, 479 size_t datalen, 480 struct key *keyring, 481 struct key *authkey) 482 { 483 struct key_preparsed_payload prep; 484 struct assoc_array_edit *edit; 485 int ret; 486 487 memset(&prep, 0, sizeof(prep)); 488 prep.data = data; 489 prep.datalen = datalen; 490 prep.quotalen = key->type->def_datalen; 491 prep.expiry = TIME_T_MAX; 492 if (key->type->preparse) { 493 ret = key->type->preparse(&prep); 494 if (ret < 0) 495 goto error; 496 } 497 498 if (keyring) { 499 ret = __key_link_begin(keyring, &key->index_key, &edit); 500 if (ret < 0) 501 goto error; 502 } 503 504 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit); 505 506 if (keyring) 507 __key_link_end(keyring, &key->index_key, edit); 508 509 error: 510 if (key->type->preparse) 511 key->type->free_preparse(&prep); 512 return ret; 513 } 514 515 EXPORT_SYMBOL(key_instantiate_and_link); 516 517 /** 518 * key_reject_and_link - Negatively instantiate a key and link it into the keyring. 519 * @key: The key to instantiate. 520 * @timeout: The timeout on the negative key. 521 * @error: The error to return when the key is hit. 522 * @keyring: Keyring to create a link in on success (or NULL). 523 * @authkey: The authorisation token permitting instantiation. 524 * 525 * Negatively instantiate a key that's in the uninstantiated state and, if 526 * successful, set its timeout and stored error and link it in to the 527 * destination keyring if one is supplied. The key and any links to the key 528 * will be automatically garbage collected after the timeout expires. 529 * 530 * Negative keys are used to rate limit repeated request_key() calls by causing 531 * them to return the stored error code (typically ENOKEY) until the negative 532 * key expires. 533 * 534 * If successful, 0 is returned, the authorisation token is revoked and anyone 535 * waiting for the key is woken up. If the key was already instantiated, 536 * -EBUSY will be returned. 537 */ 538 int key_reject_and_link(struct key *key, 539 unsigned timeout, 540 unsigned error, 541 struct key *keyring, 542 struct key *authkey) 543 { 544 struct assoc_array_edit *edit; 545 struct timespec now; 546 int ret, awaken, link_ret = 0; 547 548 key_check(key); 549 key_check(keyring); 550 551 awaken = 0; 552 ret = -EBUSY; 553 554 if (keyring) 555 link_ret = __key_link_begin(keyring, &key->index_key, &edit); 556 557 mutex_lock(&key_construction_mutex); 558 559 /* can't instantiate twice */ 560 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { 561 /* mark the key as being negatively instantiated */ 562 atomic_inc(&key->user->nikeys); 563 key->reject_error = -error; 564 smp_wmb(); 565 set_bit(KEY_FLAG_NEGATIVE, &key->flags); 566 set_bit(KEY_FLAG_INSTANTIATED, &key->flags); 567 now = current_kernel_time(); 568 key->expiry = now.tv_sec + timeout; 569 key_schedule_gc(key->expiry + key_gc_delay); 570 571 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) 572 awaken = 1; 573 574 ret = 0; 575 576 /* and link it into the destination keyring */ 577 if (keyring && link_ret == 0) 578 __key_link(key, &edit); 579 580 /* disable the authorisation key */ 581 if (authkey) 582 key_revoke(authkey); 583 } 584 585 mutex_unlock(&key_construction_mutex); 586 587 if (keyring) 588 __key_link_end(keyring, &key->index_key, edit); 589 590 /* wake up anyone waiting for a key to be constructed */ 591 if (awaken) 592 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); 593 594 return ret == 0 ? link_ret : ret; 595 } 596 EXPORT_SYMBOL(key_reject_and_link); 597 598 /** 599 * key_put - Discard a reference to a key. 600 * @key: The key to discard a reference from. 601 * 602 * Discard a reference to a key, and when all the references are gone, we 603 * schedule the cleanup task to come and pull it out of the tree in process 604 * context at some later time. 605 */ 606 void key_put(struct key *key) 607 { 608 if (key) { 609 key_check(key); 610 611 if (atomic_dec_and_test(&key->usage)) 612 schedule_work(&key_gc_work); 613 } 614 } 615 EXPORT_SYMBOL(key_put); 616 617 /* 618 * Find a key by its serial number. 619 */ 620 struct key *key_lookup(key_serial_t id) 621 { 622 struct rb_node *n; 623 struct key *key; 624 625 spin_lock(&key_serial_lock); 626 627 /* search the tree for the specified key */ 628 n = key_serial_tree.rb_node; 629 while (n) { 630 key = rb_entry(n, struct key, serial_node); 631 632 if (id < key->serial) 633 n = n->rb_left; 634 else if (id > key->serial) 635 n = n->rb_right; 636 else 637 goto found; 638 } 639 640 not_found: 641 key = ERR_PTR(-ENOKEY); 642 goto error; 643 644 found: 645 /* pretend it doesn't exist if it is awaiting deletion */ 646 if (atomic_read(&key->usage) == 0) 647 goto not_found; 648 649 /* this races with key_put(), but that doesn't matter since key_put() 650 * doesn't actually change the key 651 */ 652 __key_get(key); 653 654 error: 655 spin_unlock(&key_serial_lock); 656 return key; 657 } 658 659 /* 660 * Find and lock the specified key type against removal. 661 * 662 * We return with the sem read-locked if successful. If the type wasn't 663 * available -ENOKEY is returned instead. 664 */ 665 struct key_type *key_type_lookup(const char *type) 666 { 667 struct key_type *ktype; 668 669 down_read(&key_types_sem); 670 671 /* look up the key type to see if it's one of the registered kernel 672 * types */ 673 list_for_each_entry(ktype, &key_types_list, link) { 674 if (strcmp(ktype->name, type) == 0) 675 goto found_kernel_type; 676 } 677 678 up_read(&key_types_sem); 679 ktype = ERR_PTR(-ENOKEY); 680 681 found_kernel_type: 682 return ktype; 683 } 684 685 void key_set_timeout(struct key *key, unsigned timeout) 686 { 687 struct timespec now; 688 time_t expiry = 0; 689 690 /* make the changes with the locks held to prevent races */ 691 down_write(&key->sem); 692 693 if (timeout > 0) { 694 now = current_kernel_time(); 695 expiry = now.tv_sec + timeout; 696 } 697 698 key->expiry = expiry; 699 key_schedule_gc(key->expiry + key_gc_delay); 700 701 up_write(&key->sem); 702 } 703 EXPORT_SYMBOL_GPL(key_set_timeout); 704 705 /* 706 * Unlock a key type locked by key_type_lookup(). 707 */ 708 void key_type_put(struct key_type *ktype) 709 { 710 up_read(&key_types_sem); 711 } 712 713 /* 714 * Attempt to update an existing key. 715 * 716 * The key is given to us with an incremented refcount that we need to discard 717 * if we get an error. 718 */ 719 static inline key_ref_t __key_update(key_ref_t key_ref, 720 struct key_preparsed_payload *prep) 721 { 722 struct key *key = key_ref_to_ptr(key_ref); 723 int ret; 724 725 /* need write permission on the key to update it */ 726 ret = key_permission(key_ref, KEY_NEED_WRITE); 727 if (ret < 0) 728 goto error; 729 730 ret = -EEXIST; 731 if (!key->type->update) 732 goto error; 733 734 down_write(&key->sem); 735 736 ret = key->type->update(key, prep); 737 if (ret == 0) 738 /* updating a negative key instantiates it */ 739 clear_bit(KEY_FLAG_NEGATIVE, &key->flags); 740 741 up_write(&key->sem); 742 743 if (ret < 0) 744 goto error; 745 out: 746 return key_ref; 747 748 error: 749 key_put(key); 750 key_ref = ERR_PTR(ret); 751 goto out; 752 } 753 754 /** 755 * key_create_or_update - Update or create and instantiate a key. 756 * @keyring_ref: A pointer to the destination keyring with possession flag. 757 * @type: The type of key. 758 * @description: The searchable description for the key. 759 * @payload: The data to use to instantiate or update the key. 760 * @plen: The length of @payload. 761 * @perm: The permissions mask for a new key. 762 * @flags: The quota flags for a new key. 763 * 764 * Search the destination keyring for a key of the same description and if one 765 * is found, update it, otherwise create and instantiate a new one and create a 766 * link to it from that keyring. 767 * 768 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be 769 * concocted. 770 * 771 * Returns a pointer to the new key if successful, -ENODEV if the key type 772 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the 773 * caller isn't permitted to modify the keyring or the LSM did not permit 774 * creation of the key. 775 * 776 * On success, the possession flag from the keyring ref will be tacked on to 777 * the key ref before it is returned. 778 */ 779 key_ref_t key_create_or_update(key_ref_t keyring_ref, 780 const char *type, 781 const char *description, 782 const void *payload, 783 size_t plen, 784 key_perm_t perm, 785 unsigned long flags) 786 { 787 struct keyring_index_key index_key = { 788 .description = description, 789 }; 790 struct key_preparsed_payload prep; 791 struct assoc_array_edit *edit; 792 const struct cred *cred = current_cred(); 793 struct key *keyring, *key = NULL; 794 key_ref_t key_ref; 795 int ret; 796 797 /* look up the key type to see if it's one of the registered kernel 798 * types */ 799 index_key.type = key_type_lookup(type); 800 if (IS_ERR(index_key.type)) { 801 key_ref = ERR_PTR(-ENODEV); 802 goto error; 803 } 804 805 key_ref = ERR_PTR(-EINVAL); 806 if (!index_key.type->instantiate || 807 (!index_key.description && !index_key.type->preparse)) 808 goto error_put_type; 809 810 keyring = key_ref_to_ptr(keyring_ref); 811 812 key_check(keyring); 813 814 key_ref = ERR_PTR(-ENOTDIR); 815 if (keyring->type != &key_type_keyring) 816 goto error_put_type; 817 818 memset(&prep, 0, sizeof(prep)); 819 prep.data = payload; 820 prep.datalen = plen; 821 prep.quotalen = index_key.type->def_datalen; 822 prep.trusted = flags & KEY_ALLOC_TRUSTED; 823 prep.expiry = TIME_T_MAX; 824 if (index_key.type->preparse) { 825 ret = index_key.type->preparse(&prep); 826 if (ret < 0) { 827 key_ref = ERR_PTR(ret); 828 goto error_free_prep; 829 } 830 if (!index_key.description) 831 index_key.description = prep.description; 832 key_ref = ERR_PTR(-EINVAL); 833 if (!index_key.description) 834 goto error_free_prep; 835 } 836 index_key.desc_len = strlen(index_key.description); 837 838 key_ref = ERR_PTR(-EPERM); 839 if (!prep.trusted && test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags)) 840 goto error_free_prep; 841 flags |= prep.trusted ? KEY_ALLOC_TRUSTED : 0; 842 843 ret = __key_link_begin(keyring, &index_key, &edit); 844 if (ret < 0) { 845 key_ref = ERR_PTR(ret); 846 goto error_free_prep; 847 } 848 849 /* if we're going to allocate a new key, we're going to have 850 * to modify the keyring */ 851 ret = key_permission(keyring_ref, KEY_NEED_WRITE); 852 if (ret < 0) { 853 key_ref = ERR_PTR(ret); 854 goto error_link_end; 855 } 856 857 /* if it's possible to update this type of key, search for an existing 858 * key of the same type and description in the destination keyring and 859 * update that instead if possible 860 */ 861 if (index_key.type->update) { 862 key_ref = find_key_to_update(keyring_ref, &index_key); 863 if (key_ref) 864 goto found_matching_key; 865 } 866 867 /* if the client doesn't provide, decide on the permissions we want */ 868 if (perm == KEY_PERM_UNDEF) { 869 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR; 870 perm |= KEY_USR_VIEW; 871 872 if (index_key.type->read) 873 perm |= KEY_POS_READ; 874 875 if (index_key.type == &key_type_keyring || 876 index_key.type->update) 877 perm |= KEY_POS_WRITE; 878 } 879 880 /* allocate a new key */ 881 key = key_alloc(index_key.type, index_key.description, 882 cred->fsuid, cred->fsgid, cred, perm, flags); 883 if (IS_ERR(key)) { 884 key_ref = ERR_CAST(key); 885 goto error_link_end; 886 } 887 888 /* instantiate it and link it into the target keyring */ 889 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit); 890 if (ret < 0) { 891 key_put(key); 892 key_ref = ERR_PTR(ret); 893 goto error_link_end; 894 } 895 896 key_ref = make_key_ref(key, is_key_possessed(keyring_ref)); 897 898 error_link_end: 899 __key_link_end(keyring, &index_key, edit); 900 error_free_prep: 901 if (index_key.type->preparse) 902 index_key.type->free_preparse(&prep); 903 error_put_type: 904 key_type_put(index_key.type); 905 error: 906 return key_ref; 907 908 found_matching_key: 909 /* we found a matching key, so we're going to try to update it 910 * - we can drop the locks first as we have the key pinned 911 */ 912 __key_link_end(keyring, &index_key, edit); 913 914 key_ref = __key_update(key_ref, &prep); 915 goto error_free_prep; 916 } 917 EXPORT_SYMBOL(key_create_or_update); 918 919 /** 920 * key_update - Update a key's contents. 921 * @key_ref: The pointer (plus possession flag) to the key. 922 * @payload: The data to be used to update the key. 923 * @plen: The length of @payload. 924 * 925 * Attempt to update the contents of a key with the given payload data. The 926 * caller must be granted Write permission on the key. Negative keys can be 927 * instantiated by this method. 928 * 929 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key 930 * type does not support updating. The key type may return other errors. 931 */ 932 int key_update(key_ref_t key_ref, const void *payload, size_t plen) 933 { 934 struct key_preparsed_payload prep; 935 struct key *key = key_ref_to_ptr(key_ref); 936 int ret; 937 938 key_check(key); 939 940 /* the key must be writable */ 941 ret = key_permission(key_ref, KEY_NEED_WRITE); 942 if (ret < 0) 943 goto error; 944 945 /* attempt to update it if supported */ 946 ret = -EOPNOTSUPP; 947 if (!key->type->update) 948 goto error; 949 950 memset(&prep, 0, sizeof(prep)); 951 prep.data = payload; 952 prep.datalen = plen; 953 prep.quotalen = key->type->def_datalen; 954 prep.expiry = TIME_T_MAX; 955 if (key->type->preparse) { 956 ret = key->type->preparse(&prep); 957 if (ret < 0) 958 goto error; 959 } 960 961 down_write(&key->sem); 962 963 ret = key->type->update(key, &prep); 964 if (ret == 0) 965 /* updating a negative key instantiates it */ 966 clear_bit(KEY_FLAG_NEGATIVE, &key->flags); 967 968 up_write(&key->sem); 969 970 error: 971 if (key->type->preparse) 972 key->type->free_preparse(&prep); 973 return ret; 974 } 975 EXPORT_SYMBOL(key_update); 976 977 /** 978 * key_revoke - Revoke a key. 979 * @key: The key to be revoked. 980 * 981 * Mark a key as being revoked and ask the type to free up its resources. The 982 * revocation timeout is set and the key and all its links will be 983 * automatically garbage collected after key_gc_delay amount of time if they 984 * are not manually dealt with first. 985 */ 986 void key_revoke(struct key *key) 987 { 988 struct timespec now; 989 time_t time; 990 991 key_check(key); 992 993 /* make sure no one's trying to change or use the key when we mark it 994 * - we tell lockdep that we might nest because we might be revoking an 995 * authorisation key whilst holding the sem on a key we've just 996 * instantiated 997 */ 998 down_write_nested(&key->sem, 1); 999 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) && 1000 key->type->revoke) 1001 key->type->revoke(key); 1002 1003 /* set the death time to no more than the expiry time */ 1004 now = current_kernel_time(); 1005 time = now.tv_sec; 1006 if (key->revoked_at == 0 || key->revoked_at > time) { 1007 key->revoked_at = time; 1008 key_schedule_gc(key->revoked_at + key_gc_delay); 1009 } 1010 1011 up_write(&key->sem); 1012 } 1013 EXPORT_SYMBOL(key_revoke); 1014 1015 /** 1016 * key_invalidate - Invalidate a key. 1017 * @key: The key to be invalidated. 1018 * 1019 * Mark a key as being invalidated and have it cleaned up immediately. The key 1020 * is ignored by all searches and other operations from this point. 1021 */ 1022 void key_invalidate(struct key *key) 1023 { 1024 kenter("%d", key_serial(key)); 1025 1026 key_check(key); 1027 1028 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) { 1029 down_write_nested(&key->sem, 1); 1030 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags)) 1031 key_schedule_gc_links(); 1032 up_write(&key->sem); 1033 } 1034 } 1035 EXPORT_SYMBOL(key_invalidate); 1036 1037 /** 1038 * generic_key_instantiate - Simple instantiation of a key from preparsed data 1039 * @key: The key to be instantiated 1040 * @prep: The preparsed data to load. 1041 * 1042 * Instantiate a key from preparsed data. We assume we can just copy the data 1043 * in directly and clear the old pointers. 1044 * 1045 * This can be pointed to directly by the key type instantiate op pointer. 1046 */ 1047 int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep) 1048 { 1049 int ret; 1050 1051 pr_devel("==>%s()\n", __func__); 1052 1053 ret = key_payload_reserve(key, prep->quotalen); 1054 if (ret == 0) { 1055 rcu_assign_keypointer(key, prep->payload.data[0]); 1056 key->payload.data[1] = prep->payload.data[1]; 1057 key->payload.data[2] = prep->payload.data[2]; 1058 key->payload.data[3] = prep->payload.data[3]; 1059 prep->payload.data[0] = NULL; 1060 prep->payload.data[1] = NULL; 1061 prep->payload.data[2] = NULL; 1062 prep->payload.data[3] = NULL; 1063 } 1064 pr_devel("<==%s() = %d\n", __func__, ret); 1065 return ret; 1066 } 1067 EXPORT_SYMBOL(generic_key_instantiate); 1068 1069 /** 1070 * register_key_type - Register a type of key. 1071 * @ktype: The new key type. 1072 * 1073 * Register a new key type. 1074 * 1075 * Returns 0 on success or -EEXIST if a type of this name already exists. 1076 */ 1077 int register_key_type(struct key_type *ktype) 1078 { 1079 struct key_type *p; 1080 int ret; 1081 1082 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class)); 1083 1084 ret = -EEXIST; 1085 down_write(&key_types_sem); 1086 1087 /* disallow key types with the same name */ 1088 list_for_each_entry(p, &key_types_list, link) { 1089 if (strcmp(p->name, ktype->name) == 0) 1090 goto out; 1091 } 1092 1093 /* store the type */ 1094 list_add(&ktype->link, &key_types_list); 1095 1096 pr_notice("Key type %s registered\n", ktype->name); 1097 ret = 0; 1098 1099 out: 1100 up_write(&key_types_sem); 1101 return ret; 1102 } 1103 EXPORT_SYMBOL(register_key_type); 1104 1105 /** 1106 * unregister_key_type - Unregister a type of key. 1107 * @ktype: The key type. 1108 * 1109 * Unregister a key type and mark all the extant keys of this type as dead. 1110 * Those keys of this type are then destroyed to get rid of their payloads and 1111 * they and their links will be garbage collected as soon as possible. 1112 */ 1113 void unregister_key_type(struct key_type *ktype) 1114 { 1115 down_write(&key_types_sem); 1116 list_del_init(&ktype->link); 1117 downgrade_write(&key_types_sem); 1118 key_gc_keytype(ktype); 1119 pr_notice("Key type %s unregistered\n", ktype->name); 1120 up_read(&key_types_sem); 1121 } 1122 EXPORT_SYMBOL(unregister_key_type); 1123 1124 /* 1125 * Initialise the key management state. 1126 */ 1127 void __init key_init(void) 1128 { 1129 /* allocate a slab in which we can store keys */ 1130 key_jar = kmem_cache_create("key_jar", sizeof(struct key), 1131 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 1132 1133 /* add the special key types */ 1134 list_add_tail(&key_type_keyring.link, &key_types_list); 1135 list_add_tail(&key_type_dead.link, &key_types_list); 1136 list_add_tail(&key_type_user.link, &key_types_list); 1137 list_add_tail(&key_type_logon.link, &key_types_list); 1138 1139 /* record the root user tracking */ 1140 rb_link_node(&root_key_user.node, 1141 NULL, 1142 &key_user_tree.rb_node); 1143 1144 rb_insert_color(&root_key_user.node, 1145 &key_user_tree); 1146 } 1147