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->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; 299 300 #ifdef KEY_DEBUGGING 301 key->magic = KEY_DEBUG_MAGIC; 302 #endif 303 304 /* let the security module know about the key */ 305 ret = security_key_alloc(key, cred, flags); 306 if (ret < 0) 307 goto security_error; 308 309 /* publish the key by giving it a serial number */ 310 atomic_inc(&user->nkeys); 311 key_alloc_serial(key); 312 313 error: 314 return key; 315 316 security_error: 317 kfree(key->description); 318 kmem_cache_free(key_jar, key); 319 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { 320 spin_lock(&user->lock); 321 user->qnkeys--; 322 user->qnbytes -= quotalen; 323 spin_unlock(&user->lock); 324 } 325 key_user_put(user); 326 key = ERR_PTR(ret); 327 goto error; 328 329 no_memory_3: 330 kmem_cache_free(key_jar, key); 331 no_memory_2: 332 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { 333 spin_lock(&user->lock); 334 user->qnkeys--; 335 user->qnbytes -= quotalen; 336 spin_unlock(&user->lock); 337 } 338 key_user_put(user); 339 no_memory_1: 340 key = ERR_PTR(-ENOMEM); 341 goto error; 342 343 no_quota: 344 spin_unlock(&user->lock); 345 key_user_put(user); 346 key = ERR_PTR(-EDQUOT); 347 goto error; 348 } 349 EXPORT_SYMBOL(key_alloc); 350 351 /** 352 * key_payload_reserve - Adjust data quota reservation for the key's payload 353 * @key: The key to make the reservation for. 354 * @datalen: The amount of data payload the caller now wants. 355 * 356 * Adjust the amount of the owning user's key data quota that a key reserves. 357 * If the amount is increased, then -EDQUOT may be returned if there isn't 358 * enough free quota available. 359 * 360 * If successful, 0 is returned. 361 */ 362 int key_payload_reserve(struct key *key, size_t datalen) 363 { 364 int delta = (int)datalen - key->datalen; 365 int ret = 0; 366 367 key_check(key); 368 369 /* contemplate the quota adjustment */ 370 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) { 371 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ? 372 key_quota_root_maxbytes : key_quota_maxbytes; 373 374 spin_lock(&key->user->lock); 375 376 if (delta > 0 && 377 (key->user->qnbytes + delta >= maxbytes || 378 key->user->qnbytes + delta < key->user->qnbytes)) { 379 ret = -EDQUOT; 380 } 381 else { 382 key->user->qnbytes += delta; 383 key->quotalen += delta; 384 } 385 spin_unlock(&key->user->lock); 386 } 387 388 /* change the recorded data length if that didn't generate an error */ 389 if (ret == 0) 390 key->datalen = datalen; 391 392 return ret; 393 } 394 EXPORT_SYMBOL(key_payload_reserve); 395 396 /* 397 * Instantiate a key and link it into the target keyring atomically. Must be 398 * called with the target keyring's semaphore writelocked. The target key's 399 * semaphore need not be locked as instantiation is serialised by 400 * key_construction_mutex. 401 */ 402 static int __key_instantiate_and_link(struct key *key, 403 struct key_preparsed_payload *prep, 404 struct key *keyring, 405 struct key *authkey, 406 struct assoc_array_edit **_edit) 407 { 408 int ret, awaken; 409 410 key_check(key); 411 key_check(keyring); 412 413 awaken = 0; 414 ret = -EBUSY; 415 416 mutex_lock(&key_construction_mutex); 417 418 /* can't instantiate twice */ 419 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { 420 /* instantiate the key */ 421 ret = key->type->instantiate(key, prep); 422 423 if (ret == 0) { 424 /* mark the key as being instantiated */ 425 atomic_inc(&key->user->nikeys); 426 set_bit(KEY_FLAG_INSTANTIATED, &key->flags); 427 428 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) 429 awaken = 1; 430 431 /* and link it into the destination keyring */ 432 if (keyring) 433 __key_link(key, _edit); 434 435 /* disable the authorisation key */ 436 if (authkey) 437 key_revoke(authkey); 438 439 if (prep->expiry != TIME_T_MAX) { 440 key->expiry = prep->expiry; 441 key_schedule_gc(prep->expiry + key_gc_delay); 442 } 443 } 444 } 445 446 mutex_unlock(&key_construction_mutex); 447 448 /* wake up anyone waiting for a key to be constructed */ 449 if (awaken) 450 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); 451 452 return ret; 453 } 454 455 /** 456 * key_instantiate_and_link - Instantiate a key and link it into the keyring. 457 * @key: The key to instantiate. 458 * @data: The data to use to instantiate the keyring. 459 * @datalen: The length of @data. 460 * @keyring: Keyring to create a link in on success (or NULL). 461 * @authkey: The authorisation token permitting instantiation. 462 * 463 * Instantiate a key that's in the uninstantiated state using the provided data 464 * and, if successful, link it in to the destination keyring if one is 465 * supplied. 466 * 467 * If successful, 0 is returned, the authorisation token is revoked and anyone 468 * waiting for the key is woken up. If the key was already instantiated, 469 * -EBUSY will be returned. 470 */ 471 int key_instantiate_and_link(struct key *key, 472 const void *data, 473 size_t datalen, 474 struct key *keyring, 475 struct key *authkey) 476 { 477 struct key_preparsed_payload prep; 478 struct assoc_array_edit *edit; 479 int ret; 480 481 memset(&prep, 0, sizeof(prep)); 482 prep.data = data; 483 prep.datalen = datalen; 484 prep.quotalen = key->type->def_datalen; 485 prep.expiry = TIME_T_MAX; 486 if (key->type->preparse) { 487 ret = key->type->preparse(&prep); 488 if (ret < 0) 489 goto error; 490 } 491 492 if (keyring) { 493 ret = __key_link_begin(keyring, &key->index_key, &edit); 494 if (ret < 0) 495 goto error; 496 } 497 498 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit); 499 500 if (keyring) 501 __key_link_end(keyring, &key->index_key, edit); 502 503 error: 504 if (key->type->preparse) 505 key->type->free_preparse(&prep); 506 return ret; 507 } 508 509 EXPORT_SYMBOL(key_instantiate_and_link); 510 511 /** 512 * key_reject_and_link - Negatively instantiate a key and link it into the keyring. 513 * @key: The key to instantiate. 514 * @timeout: The timeout on the negative key. 515 * @error: The error to return when the key is hit. 516 * @keyring: Keyring to create a link in on success (or NULL). 517 * @authkey: The authorisation token permitting instantiation. 518 * 519 * Negatively instantiate a key that's in the uninstantiated state and, if 520 * successful, set its timeout and stored error and link it in to the 521 * destination keyring if one is supplied. The key and any links to the key 522 * will be automatically garbage collected after the timeout expires. 523 * 524 * Negative keys are used to rate limit repeated request_key() calls by causing 525 * them to return the stored error code (typically ENOKEY) until the negative 526 * key expires. 527 * 528 * If successful, 0 is returned, the authorisation token is revoked and anyone 529 * waiting for the key is woken up. If the key was already instantiated, 530 * -EBUSY will be returned. 531 */ 532 int key_reject_and_link(struct key *key, 533 unsigned timeout, 534 unsigned error, 535 struct key *keyring, 536 struct key *authkey) 537 { 538 struct assoc_array_edit *edit; 539 struct timespec now; 540 int ret, awaken, link_ret = 0; 541 542 key_check(key); 543 key_check(keyring); 544 545 awaken = 0; 546 ret = -EBUSY; 547 548 if (keyring) 549 link_ret = __key_link_begin(keyring, &key->index_key, &edit); 550 551 mutex_lock(&key_construction_mutex); 552 553 /* can't instantiate twice */ 554 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { 555 /* mark the key as being negatively instantiated */ 556 atomic_inc(&key->user->nikeys); 557 key->type_data.reject_error = -error; 558 smp_wmb(); 559 set_bit(KEY_FLAG_NEGATIVE, &key->flags); 560 set_bit(KEY_FLAG_INSTANTIATED, &key->flags); 561 now = current_kernel_time(); 562 key->expiry = now.tv_sec + timeout; 563 key_schedule_gc(key->expiry + key_gc_delay); 564 565 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) 566 awaken = 1; 567 568 ret = 0; 569 570 /* and link it into the destination keyring */ 571 if (keyring && link_ret == 0) 572 __key_link(key, &edit); 573 574 /* disable the authorisation key */ 575 if (authkey) 576 key_revoke(authkey); 577 } 578 579 mutex_unlock(&key_construction_mutex); 580 581 if (keyring) 582 __key_link_end(keyring, &key->index_key, edit); 583 584 /* wake up anyone waiting for a key to be constructed */ 585 if (awaken) 586 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); 587 588 return ret == 0 ? link_ret : ret; 589 } 590 EXPORT_SYMBOL(key_reject_and_link); 591 592 /** 593 * key_put - Discard a reference to a key. 594 * @key: The key to discard a reference from. 595 * 596 * Discard a reference to a key, and when all the references are gone, we 597 * schedule the cleanup task to come and pull it out of the tree in process 598 * context at some later time. 599 */ 600 void key_put(struct key *key) 601 { 602 if (key) { 603 key_check(key); 604 605 if (atomic_dec_and_test(&key->usage)) 606 schedule_work(&key_gc_work); 607 } 608 } 609 EXPORT_SYMBOL(key_put); 610 611 /* 612 * Find a key by its serial number. 613 */ 614 struct key *key_lookup(key_serial_t id) 615 { 616 struct rb_node *n; 617 struct key *key; 618 619 spin_lock(&key_serial_lock); 620 621 /* search the tree for the specified key */ 622 n = key_serial_tree.rb_node; 623 while (n) { 624 key = rb_entry(n, struct key, serial_node); 625 626 if (id < key->serial) 627 n = n->rb_left; 628 else if (id > key->serial) 629 n = n->rb_right; 630 else 631 goto found; 632 } 633 634 not_found: 635 key = ERR_PTR(-ENOKEY); 636 goto error; 637 638 found: 639 /* pretend it doesn't exist if it is awaiting deletion */ 640 if (atomic_read(&key->usage) == 0) 641 goto not_found; 642 643 /* this races with key_put(), but that doesn't matter since key_put() 644 * doesn't actually change the key 645 */ 646 __key_get(key); 647 648 error: 649 spin_unlock(&key_serial_lock); 650 return key; 651 } 652 653 /* 654 * Find and lock the specified key type against removal. 655 * 656 * We return with the sem read-locked if successful. If the type wasn't 657 * available -ENOKEY is returned instead. 658 */ 659 struct key_type *key_type_lookup(const char *type) 660 { 661 struct key_type *ktype; 662 663 down_read(&key_types_sem); 664 665 /* look up the key type to see if it's one of the registered kernel 666 * types */ 667 list_for_each_entry(ktype, &key_types_list, link) { 668 if (strcmp(ktype->name, type) == 0) 669 goto found_kernel_type; 670 } 671 672 up_read(&key_types_sem); 673 ktype = ERR_PTR(-ENOKEY); 674 675 found_kernel_type: 676 return ktype; 677 } 678 679 void key_set_timeout(struct key *key, unsigned timeout) 680 { 681 struct timespec now; 682 time_t expiry = 0; 683 684 /* make the changes with the locks held to prevent races */ 685 down_write(&key->sem); 686 687 if (timeout > 0) { 688 now = current_kernel_time(); 689 expiry = now.tv_sec + timeout; 690 } 691 692 key->expiry = expiry; 693 key_schedule_gc(key->expiry + key_gc_delay); 694 695 up_write(&key->sem); 696 } 697 EXPORT_SYMBOL_GPL(key_set_timeout); 698 699 /* 700 * Unlock a key type locked by key_type_lookup(). 701 */ 702 void key_type_put(struct key_type *ktype) 703 { 704 up_read(&key_types_sem); 705 } 706 707 /* 708 * Attempt to update an existing key. 709 * 710 * The key is given to us with an incremented refcount that we need to discard 711 * if we get an error. 712 */ 713 static inline key_ref_t __key_update(key_ref_t key_ref, 714 struct key_preparsed_payload *prep) 715 { 716 struct key *key = key_ref_to_ptr(key_ref); 717 int ret; 718 719 /* need write permission on the key to update it */ 720 ret = key_permission(key_ref, KEY_NEED_WRITE); 721 if (ret < 0) 722 goto error; 723 724 ret = -EEXIST; 725 if (!key->type->update) 726 goto error; 727 728 down_write(&key->sem); 729 730 ret = key->type->update(key, prep); 731 if (ret == 0) 732 /* updating a negative key instantiates it */ 733 clear_bit(KEY_FLAG_NEGATIVE, &key->flags); 734 735 up_write(&key->sem); 736 737 if (ret < 0) 738 goto error; 739 out: 740 return key_ref; 741 742 error: 743 key_put(key); 744 key_ref = ERR_PTR(ret); 745 goto out; 746 } 747 748 /** 749 * key_create_or_update - Update or create and instantiate a key. 750 * @keyring_ref: A pointer to the destination keyring with possession flag. 751 * @type: The type of key. 752 * @description: The searchable description for the key. 753 * @payload: The data to use to instantiate or update the key. 754 * @plen: The length of @payload. 755 * @perm: The permissions mask for a new key. 756 * @flags: The quota flags for a new key. 757 * 758 * Search the destination keyring for a key of the same description and if one 759 * is found, update it, otherwise create and instantiate a new one and create a 760 * link to it from that keyring. 761 * 762 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be 763 * concocted. 764 * 765 * Returns a pointer to the new key if successful, -ENODEV if the key type 766 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the 767 * caller isn't permitted to modify the keyring or the LSM did not permit 768 * creation of the key. 769 * 770 * On success, the possession flag from the keyring ref will be tacked on to 771 * the key ref before it is returned. 772 */ 773 key_ref_t key_create_or_update(key_ref_t keyring_ref, 774 const char *type, 775 const char *description, 776 const void *payload, 777 size_t plen, 778 key_perm_t perm, 779 unsigned long flags) 780 { 781 struct keyring_index_key index_key = { 782 .description = description, 783 }; 784 struct key_preparsed_payload prep; 785 struct assoc_array_edit *edit; 786 const struct cred *cred = current_cred(); 787 struct key *keyring, *key = NULL; 788 key_ref_t key_ref; 789 int ret; 790 791 /* look up the key type to see if it's one of the registered kernel 792 * types */ 793 index_key.type = key_type_lookup(type); 794 if (IS_ERR(index_key.type)) { 795 key_ref = ERR_PTR(-ENODEV); 796 goto error; 797 } 798 799 key_ref = ERR_PTR(-EINVAL); 800 if (!index_key.type->instantiate || 801 (!index_key.description && !index_key.type->preparse)) 802 goto error_put_type; 803 804 keyring = key_ref_to_ptr(keyring_ref); 805 806 key_check(keyring); 807 808 key_ref = ERR_PTR(-ENOTDIR); 809 if (keyring->type != &key_type_keyring) 810 goto error_put_type; 811 812 memset(&prep, 0, sizeof(prep)); 813 prep.data = payload; 814 prep.datalen = plen; 815 prep.quotalen = index_key.type->def_datalen; 816 prep.trusted = flags & KEY_ALLOC_TRUSTED; 817 prep.expiry = TIME_T_MAX; 818 if (index_key.type->preparse) { 819 ret = index_key.type->preparse(&prep); 820 if (ret < 0) { 821 key_ref = ERR_PTR(ret); 822 goto error_free_prep; 823 } 824 if (!index_key.description) 825 index_key.description = prep.description; 826 key_ref = ERR_PTR(-EINVAL); 827 if (!index_key.description) 828 goto error_free_prep; 829 } 830 index_key.desc_len = strlen(index_key.description); 831 832 key_ref = ERR_PTR(-EPERM); 833 if (!prep.trusted && test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags)) 834 goto error_free_prep; 835 flags |= prep.trusted ? KEY_ALLOC_TRUSTED : 0; 836 837 ret = __key_link_begin(keyring, &index_key, &edit); 838 if (ret < 0) { 839 key_ref = ERR_PTR(ret); 840 goto error_free_prep; 841 } 842 843 /* if we're going to allocate a new key, we're going to have 844 * to modify the keyring */ 845 ret = key_permission(keyring_ref, KEY_NEED_WRITE); 846 if (ret < 0) { 847 key_ref = ERR_PTR(ret); 848 goto error_link_end; 849 } 850 851 /* if it's possible to update this type of key, search for an existing 852 * key of the same type and description in the destination keyring and 853 * update that instead if possible 854 */ 855 if (index_key.type->update) { 856 key_ref = find_key_to_update(keyring_ref, &index_key); 857 if (key_ref) 858 goto found_matching_key; 859 } 860 861 /* if the client doesn't provide, decide on the permissions we want */ 862 if (perm == KEY_PERM_UNDEF) { 863 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR; 864 perm |= KEY_USR_VIEW; 865 866 if (index_key.type->read) 867 perm |= KEY_POS_READ; 868 869 if (index_key.type == &key_type_keyring || 870 index_key.type->update) 871 perm |= KEY_POS_WRITE; 872 } 873 874 /* allocate a new key */ 875 key = key_alloc(index_key.type, index_key.description, 876 cred->fsuid, cred->fsgid, cred, perm, flags); 877 if (IS_ERR(key)) { 878 key_ref = ERR_CAST(key); 879 goto error_link_end; 880 } 881 882 /* instantiate it and link it into the target keyring */ 883 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit); 884 if (ret < 0) { 885 key_put(key); 886 key_ref = ERR_PTR(ret); 887 goto error_link_end; 888 } 889 890 key_ref = make_key_ref(key, is_key_possessed(keyring_ref)); 891 892 error_link_end: 893 __key_link_end(keyring, &index_key, edit); 894 error_free_prep: 895 if (index_key.type->preparse) 896 index_key.type->free_preparse(&prep); 897 error_put_type: 898 key_type_put(index_key.type); 899 error: 900 return key_ref; 901 902 found_matching_key: 903 /* we found a matching key, so we're going to try to update it 904 * - we can drop the locks first as we have the key pinned 905 */ 906 __key_link_end(keyring, &index_key, edit); 907 908 key_ref = __key_update(key_ref, &prep); 909 goto error_free_prep; 910 } 911 EXPORT_SYMBOL(key_create_or_update); 912 913 /** 914 * key_update - Update a key's contents. 915 * @key_ref: The pointer (plus possession flag) to the key. 916 * @payload: The data to be used to update the key. 917 * @plen: The length of @payload. 918 * 919 * Attempt to update the contents of a key with the given payload data. The 920 * caller must be granted Write permission on the key. Negative keys can be 921 * instantiated by this method. 922 * 923 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key 924 * type does not support updating. The key type may return other errors. 925 */ 926 int key_update(key_ref_t key_ref, const void *payload, size_t plen) 927 { 928 struct key_preparsed_payload prep; 929 struct key *key = key_ref_to_ptr(key_ref); 930 int ret; 931 932 key_check(key); 933 934 /* the key must be writable */ 935 ret = key_permission(key_ref, KEY_NEED_WRITE); 936 if (ret < 0) 937 goto error; 938 939 /* attempt to update it if supported */ 940 ret = -EOPNOTSUPP; 941 if (!key->type->update) 942 goto error; 943 944 memset(&prep, 0, sizeof(prep)); 945 prep.data = payload; 946 prep.datalen = plen; 947 prep.quotalen = key->type->def_datalen; 948 prep.expiry = TIME_T_MAX; 949 if (key->type->preparse) { 950 ret = key->type->preparse(&prep); 951 if (ret < 0) 952 goto error; 953 } 954 955 down_write(&key->sem); 956 957 ret = key->type->update(key, &prep); 958 if (ret == 0) 959 /* updating a negative key instantiates it */ 960 clear_bit(KEY_FLAG_NEGATIVE, &key->flags); 961 962 up_write(&key->sem); 963 964 error: 965 if (key->type->preparse) 966 key->type->free_preparse(&prep); 967 return ret; 968 } 969 EXPORT_SYMBOL(key_update); 970 971 /** 972 * key_revoke - Revoke a key. 973 * @key: The key to be revoked. 974 * 975 * Mark a key as being revoked and ask the type to free up its resources. The 976 * revocation timeout is set and the key and all its links will be 977 * automatically garbage collected after key_gc_delay amount of time if they 978 * are not manually dealt with first. 979 */ 980 void key_revoke(struct key *key) 981 { 982 struct timespec now; 983 time_t time; 984 985 key_check(key); 986 987 /* make sure no one's trying to change or use the key when we mark it 988 * - we tell lockdep that we might nest because we might be revoking an 989 * authorisation key whilst holding the sem on a key we've just 990 * instantiated 991 */ 992 down_write_nested(&key->sem, 1); 993 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) && 994 key->type->revoke) 995 key->type->revoke(key); 996 997 /* set the death time to no more than the expiry time */ 998 now = current_kernel_time(); 999 time = now.tv_sec; 1000 if (key->revoked_at == 0 || key->revoked_at > time) { 1001 key->revoked_at = time; 1002 key_schedule_gc(key->revoked_at + key_gc_delay); 1003 } 1004 1005 up_write(&key->sem); 1006 } 1007 EXPORT_SYMBOL(key_revoke); 1008 1009 /** 1010 * key_invalidate - Invalidate a key. 1011 * @key: The key to be invalidated. 1012 * 1013 * Mark a key as being invalidated and have it cleaned up immediately. The key 1014 * is ignored by all searches and other operations from this point. 1015 */ 1016 void key_invalidate(struct key *key) 1017 { 1018 kenter("%d", key_serial(key)); 1019 1020 key_check(key); 1021 1022 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) { 1023 down_write_nested(&key->sem, 1); 1024 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags)) 1025 key_schedule_gc_links(); 1026 up_write(&key->sem); 1027 } 1028 } 1029 EXPORT_SYMBOL(key_invalidate); 1030 1031 /** 1032 * generic_key_instantiate - Simple instantiation of a key from preparsed data 1033 * @key: The key to be instantiated 1034 * @prep: The preparsed data to load. 1035 * 1036 * Instantiate a key from preparsed data. We assume we can just copy the data 1037 * in directly and clear the old pointers. 1038 * 1039 * This can be pointed to directly by the key type instantiate op pointer. 1040 */ 1041 int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep) 1042 { 1043 int ret; 1044 1045 pr_devel("==>%s()\n", __func__); 1046 1047 ret = key_payload_reserve(key, prep->quotalen); 1048 if (ret == 0) { 1049 key->type_data.p[0] = prep->type_data[0]; 1050 key->type_data.p[1] = prep->type_data[1]; 1051 rcu_assign_keypointer(key, prep->payload[0]); 1052 key->payload.data2[1] = prep->payload[1]; 1053 prep->type_data[0] = NULL; 1054 prep->type_data[1] = NULL; 1055 prep->payload[0] = NULL; 1056 prep->payload[1] = NULL; 1057 } 1058 pr_devel("<==%s() = %d\n", __func__, ret); 1059 return ret; 1060 } 1061 EXPORT_SYMBOL(generic_key_instantiate); 1062 1063 /** 1064 * register_key_type - Register a type of key. 1065 * @ktype: The new key type. 1066 * 1067 * Register a new key type. 1068 * 1069 * Returns 0 on success or -EEXIST if a type of this name already exists. 1070 */ 1071 int register_key_type(struct key_type *ktype) 1072 { 1073 struct key_type *p; 1074 int ret; 1075 1076 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class)); 1077 1078 ret = -EEXIST; 1079 down_write(&key_types_sem); 1080 1081 /* disallow key types with the same name */ 1082 list_for_each_entry(p, &key_types_list, link) { 1083 if (strcmp(p->name, ktype->name) == 0) 1084 goto out; 1085 } 1086 1087 /* store the type */ 1088 list_add(&ktype->link, &key_types_list); 1089 1090 pr_notice("Key type %s registered\n", ktype->name); 1091 ret = 0; 1092 1093 out: 1094 up_write(&key_types_sem); 1095 return ret; 1096 } 1097 EXPORT_SYMBOL(register_key_type); 1098 1099 /** 1100 * unregister_key_type - Unregister a type of key. 1101 * @ktype: The key type. 1102 * 1103 * Unregister a key type and mark all the extant keys of this type as dead. 1104 * Those keys of this type are then destroyed to get rid of their payloads and 1105 * they and their links will be garbage collected as soon as possible. 1106 */ 1107 void unregister_key_type(struct key_type *ktype) 1108 { 1109 down_write(&key_types_sem); 1110 list_del_init(&ktype->link); 1111 downgrade_write(&key_types_sem); 1112 key_gc_keytype(ktype); 1113 pr_notice("Key type %s unregistered\n", ktype->name); 1114 up_read(&key_types_sem); 1115 } 1116 EXPORT_SYMBOL(unregister_key_type); 1117 1118 /* 1119 * Initialise the key management state. 1120 */ 1121 void __init key_init(void) 1122 { 1123 /* allocate a slab in which we can store keys */ 1124 key_jar = kmem_cache_create("key_jar", sizeof(struct key), 1125 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 1126 1127 /* add the special key types */ 1128 list_add_tail(&key_type_keyring.link, &key_types_list); 1129 list_add_tail(&key_type_dead.link, &key_types_list); 1130 list_add_tail(&key_type_user.link, &key_types_list); 1131 list_add_tail(&key_type_logon.link, &key_types_list); 1132 1133 /* record the root user tracking */ 1134 rb_link_node(&root_key_user.node, 1135 NULL, 1136 &key_user_tree.rb_node); 1137 1138 rb_insert_color(&root_key_user.node, 1139 &key_user_tree); 1140 } 1141