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 <linux/user_namespace.h> 22 #include "internal.h" 23 24 struct kmem_cache *key_jar; 25 struct rb_root key_serial_tree; /* tree of keys indexed by serial */ 26 DEFINE_SPINLOCK(key_serial_lock); 27 28 struct rb_root key_user_tree; /* tree of quota records indexed by UID */ 29 DEFINE_SPINLOCK(key_user_lock); 30 31 unsigned int key_quota_root_maxkeys = 200; /* root's key count quota */ 32 unsigned int key_quota_root_maxbytes = 20000; /* root's key space quota */ 33 unsigned int key_quota_maxkeys = 200; /* general key count quota */ 34 unsigned int key_quota_maxbytes = 20000; /* general key space quota */ 35 36 static LIST_HEAD(key_types_list); 37 static DECLARE_RWSEM(key_types_sem); 38 39 /* We serialise key instantiation and link */ 40 DEFINE_MUTEX(key_construction_mutex); 41 42 #ifdef KEY_DEBUGGING 43 void __key_check(const struct key *key) 44 { 45 printk("__key_check: key %p {%08x} should be {%08x}\n", 46 key, key->magic, KEY_DEBUG_MAGIC); 47 BUG(); 48 } 49 #endif 50 51 /* 52 * Get the key quota record for a user, allocating a new record if one doesn't 53 * already exist. 54 */ 55 struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns) 56 { 57 struct key_user *candidate = NULL, *user; 58 struct rb_node *parent = NULL; 59 struct rb_node **p; 60 61 try_again: 62 p = &key_user_tree.rb_node; 63 spin_lock(&key_user_lock); 64 65 /* search the tree for a user record with a matching UID */ 66 while (*p) { 67 parent = *p; 68 user = rb_entry(parent, struct key_user, node); 69 70 if (uid < user->uid) 71 p = &(*p)->rb_left; 72 else if (uid > user->uid) 73 p = &(*p)->rb_right; 74 else if (user_ns < user->user_ns) 75 p = &(*p)->rb_left; 76 else if (user_ns > user->user_ns) 77 p = &(*p)->rb_right; 78 else 79 goto found; 80 } 81 82 /* if we get here, we failed to find a match in the tree */ 83 if (!candidate) { 84 /* allocate a candidate user record if we don't already have 85 * one */ 86 spin_unlock(&key_user_lock); 87 88 user = NULL; 89 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL); 90 if (unlikely(!candidate)) 91 goto out; 92 93 /* the allocation may have scheduled, so we need to repeat the 94 * search lest someone else added the record whilst we were 95 * asleep */ 96 goto try_again; 97 } 98 99 /* if we get here, then the user record still hadn't appeared on the 100 * second pass - so we use the candidate record */ 101 atomic_set(&candidate->usage, 1); 102 atomic_set(&candidate->nkeys, 0); 103 atomic_set(&candidate->nikeys, 0); 104 candidate->uid = uid; 105 candidate->user_ns = get_user_ns(user_ns); 106 candidate->qnkeys = 0; 107 candidate->qnbytes = 0; 108 spin_lock_init(&candidate->lock); 109 mutex_init(&candidate->cons_lock); 110 111 rb_link_node(&candidate->node, parent, p); 112 rb_insert_color(&candidate->node, &key_user_tree); 113 spin_unlock(&key_user_lock); 114 user = candidate; 115 goto out; 116 117 /* okay - we found a user record for this UID */ 118 found: 119 atomic_inc(&user->usage); 120 spin_unlock(&key_user_lock); 121 kfree(candidate); 122 out: 123 return user; 124 } 125 126 /* 127 * Dispose of a user structure 128 */ 129 void key_user_put(struct key_user *user) 130 { 131 if (atomic_dec_and_lock(&user->usage, &key_user_lock)) { 132 rb_erase(&user->node, &key_user_tree); 133 spin_unlock(&key_user_lock); 134 put_user_ns(user->user_ns); 135 136 kfree(user); 137 } 138 } 139 140 /* 141 * Allocate a serial number for a key. These are assigned randomly to avoid 142 * security issues through covert channel problems. 143 */ 144 static inline void key_alloc_serial(struct key *key) 145 { 146 struct rb_node *parent, **p; 147 struct key *xkey; 148 149 /* propose a random serial number and look for a hole for it in the 150 * serial number tree */ 151 do { 152 get_random_bytes(&key->serial, sizeof(key->serial)); 153 154 key->serial >>= 1; /* negative numbers are not permitted */ 155 } while (key->serial < 3); 156 157 spin_lock(&key_serial_lock); 158 159 attempt_insertion: 160 parent = NULL; 161 p = &key_serial_tree.rb_node; 162 163 while (*p) { 164 parent = *p; 165 xkey = rb_entry(parent, struct key, serial_node); 166 167 if (key->serial < xkey->serial) 168 p = &(*p)->rb_left; 169 else if (key->serial > xkey->serial) 170 p = &(*p)->rb_right; 171 else 172 goto serial_exists; 173 } 174 175 /* we've found a suitable hole - arrange for this key to occupy it */ 176 rb_link_node(&key->serial_node, parent, p); 177 rb_insert_color(&key->serial_node, &key_serial_tree); 178 179 spin_unlock(&key_serial_lock); 180 return; 181 182 /* we found a key with the proposed serial number - walk the tree from 183 * that point looking for the next unused serial number */ 184 serial_exists: 185 for (;;) { 186 key->serial++; 187 if (key->serial < 3) { 188 key->serial = 3; 189 goto attempt_insertion; 190 } 191 192 parent = rb_next(parent); 193 if (!parent) 194 goto attempt_insertion; 195 196 xkey = rb_entry(parent, struct key, serial_node); 197 if (key->serial < xkey->serial) 198 goto attempt_insertion; 199 } 200 } 201 202 /** 203 * key_alloc - Allocate a key of the specified type. 204 * @type: The type of key to allocate. 205 * @desc: The key description to allow the key to be searched out. 206 * @uid: The owner of the new key. 207 * @gid: The group ID for the new key's group permissions. 208 * @cred: The credentials specifying UID namespace. 209 * @perm: The permissions mask of the new key. 210 * @flags: Flags specifying quota properties. 211 * 212 * Allocate a key of the specified type with the attributes given. The key is 213 * returned in an uninstantiated state and the caller needs to instantiate the 214 * key before returning. 215 * 216 * The user's key count quota is updated to reflect the creation of the key and 217 * the user's key data quota has the default for the key type reserved. The 218 * instantiation function should amend this as necessary. If insufficient 219 * quota is available, -EDQUOT will be returned. 220 * 221 * The LSM security modules can prevent a key being created, in which case 222 * -EACCES will be returned. 223 * 224 * Returns a pointer to the new key if successful and an error code otherwise. 225 * 226 * Note that the caller needs to ensure the key type isn't uninstantiated. 227 * Internally this can be done by locking key_types_sem. Externally, this can 228 * be done by either never unregistering the key type, or making sure 229 * key_alloc() calls don't race with module unloading. 230 */ 231 struct key *key_alloc(struct key_type *type, const char *desc, 232 uid_t uid, gid_t gid, const struct cred *cred, 233 key_perm_t perm, unsigned long flags) 234 { 235 struct key_user *user = NULL; 236 struct key *key; 237 size_t desclen, quotalen; 238 int ret; 239 240 key = ERR_PTR(-EINVAL); 241 if (!desc || !*desc) 242 goto error; 243 244 if (type->vet_description) { 245 ret = type->vet_description(desc); 246 if (ret < 0) { 247 key = ERR_PTR(ret); 248 goto error; 249 } 250 } 251 252 desclen = strlen(desc) + 1; 253 quotalen = desclen + type->def_datalen; 254 255 /* get hold of the key tracking for this user */ 256 user = key_user_lookup(uid, cred->user->user_ns); 257 if (!user) 258 goto no_memory_1; 259 260 /* check that the user's quota permits allocation of another key and 261 * its description */ 262 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { 263 unsigned maxkeys = (uid == 0) ? 264 key_quota_root_maxkeys : key_quota_maxkeys; 265 unsigned maxbytes = (uid == 0) ? 266 key_quota_root_maxbytes : key_quota_maxbytes; 267 268 spin_lock(&user->lock); 269 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) { 270 if (user->qnkeys + 1 >= maxkeys || 271 user->qnbytes + quotalen >= maxbytes || 272 user->qnbytes + quotalen < user->qnbytes) 273 goto no_quota; 274 } 275 276 user->qnkeys++; 277 user->qnbytes += quotalen; 278 spin_unlock(&user->lock); 279 } 280 281 /* allocate and initialise the key and its description */ 282 key = kmem_cache_alloc(key_jar, GFP_KERNEL); 283 if (!key) 284 goto no_memory_2; 285 286 if (desc) { 287 key->description = kmemdup(desc, desclen, GFP_KERNEL); 288 if (!key->description) 289 goto no_memory_3; 290 } 291 292 atomic_set(&key->usage, 1); 293 init_rwsem(&key->sem); 294 lockdep_set_class(&key->sem, &type->lock_class); 295 key->type = type; 296 key->user = user; 297 key->quotalen = quotalen; 298 key->datalen = type->def_datalen; 299 key->uid = uid; 300 key->gid = gid; 301 key->perm = perm; 302 key->flags = 0; 303 key->expiry = 0; 304 key->payload.data = NULL; 305 key->security = NULL; 306 307 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) 308 key->flags |= 1 << KEY_FLAG_IN_QUOTA; 309 310 memset(&key->type_data, 0, sizeof(key->type_data)); 311 312 #ifdef KEY_DEBUGGING 313 key->magic = KEY_DEBUG_MAGIC; 314 #endif 315 316 /* let the security module know about the key */ 317 ret = security_key_alloc(key, cred, flags); 318 if (ret < 0) 319 goto security_error; 320 321 /* publish the key by giving it a serial number */ 322 atomic_inc(&user->nkeys); 323 key_alloc_serial(key); 324 325 error: 326 return key; 327 328 security_error: 329 kfree(key->description); 330 kmem_cache_free(key_jar, key); 331 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { 332 spin_lock(&user->lock); 333 user->qnkeys--; 334 user->qnbytes -= quotalen; 335 spin_unlock(&user->lock); 336 } 337 key_user_put(user); 338 key = ERR_PTR(ret); 339 goto error; 340 341 no_memory_3: 342 kmem_cache_free(key_jar, key); 343 no_memory_2: 344 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { 345 spin_lock(&user->lock); 346 user->qnkeys--; 347 user->qnbytes -= quotalen; 348 spin_unlock(&user->lock); 349 } 350 key_user_put(user); 351 no_memory_1: 352 key = ERR_PTR(-ENOMEM); 353 goto error; 354 355 no_quota: 356 spin_unlock(&user->lock); 357 key_user_put(user); 358 key = ERR_PTR(-EDQUOT); 359 goto error; 360 } 361 EXPORT_SYMBOL(key_alloc); 362 363 /** 364 * key_payload_reserve - Adjust data quota reservation for the key's payload 365 * @key: The key to make the reservation for. 366 * @datalen: The amount of data payload the caller now wants. 367 * 368 * Adjust the amount of the owning user's key data quota that a key reserves. 369 * If the amount is increased, then -EDQUOT may be returned if there isn't 370 * enough free quota available. 371 * 372 * If successful, 0 is returned. 373 */ 374 int key_payload_reserve(struct key *key, size_t datalen) 375 { 376 int delta = (int)datalen - key->datalen; 377 int ret = 0; 378 379 key_check(key); 380 381 /* contemplate the quota adjustment */ 382 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) { 383 unsigned maxbytes = (key->user->uid == 0) ? 384 key_quota_root_maxbytes : key_quota_maxbytes; 385 386 spin_lock(&key->user->lock); 387 388 if (delta > 0 && 389 (key->user->qnbytes + delta >= maxbytes || 390 key->user->qnbytes + delta < key->user->qnbytes)) { 391 ret = -EDQUOT; 392 } 393 else { 394 key->user->qnbytes += delta; 395 key->quotalen += delta; 396 } 397 spin_unlock(&key->user->lock); 398 } 399 400 /* change the recorded data length if that didn't generate an error */ 401 if (ret == 0) 402 key->datalen = datalen; 403 404 return ret; 405 } 406 EXPORT_SYMBOL(key_payload_reserve); 407 408 /* 409 * Instantiate a key and link it into the target keyring atomically. Must be 410 * called with the target keyring's semaphore writelocked. The target key's 411 * semaphore need not be locked as instantiation is serialised by 412 * key_construction_mutex. 413 */ 414 static int __key_instantiate_and_link(struct key *key, 415 const void *data, 416 size_t datalen, 417 struct key *keyring, 418 struct key *authkey, 419 unsigned long *_prealloc) 420 { 421 int ret, awaken; 422 423 key_check(key); 424 key_check(keyring); 425 426 awaken = 0; 427 ret = -EBUSY; 428 429 mutex_lock(&key_construction_mutex); 430 431 /* can't instantiate twice */ 432 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { 433 /* instantiate the key */ 434 ret = key->type->instantiate(key, data, datalen); 435 436 if (ret == 0) { 437 /* mark the key as being instantiated */ 438 atomic_inc(&key->user->nikeys); 439 set_bit(KEY_FLAG_INSTANTIATED, &key->flags); 440 441 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) 442 awaken = 1; 443 444 /* and link it into the destination keyring */ 445 if (keyring) 446 __key_link(keyring, key, _prealloc); 447 448 /* disable the authorisation key */ 449 if (authkey) 450 key_revoke(authkey); 451 } 452 } 453 454 mutex_unlock(&key_construction_mutex); 455 456 /* wake up anyone waiting for a key to be constructed */ 457 if (awaken) 458 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); 459 460 return ret; 461 } 462 463 /** 464 * key_instantiate_and_link - Instantiate a key and link it into the keyring. 465 * @key: The key to instantiate. 466 * @data: The data to use to instantiate the keyring. 467 * @datalen: The length of @data. 468 * @keyring: Keyring to create a link in on success (or NULL). 469 * @authkey: The authorisation token permitting instantiation. 470 * 471 * Instantiate a key that's in the uninstantiated state using the provided data 472 * and, if successful, link it in to the destination keyring if one is 473 * supplied. 474 * 475 * If successful, 0 is returned, the authorisation token is revoked and anyone 476 * waiting for the key is woken up. If the key was already instantiated, 477 * -EBUSY will be returned. 478 */ 479 int key_instantiate_and_link(struct key *key, 480 const void *data, 481 size_t datalen, 482 struct key *keyring, 483 struct key *authkey) 484 { 485 unsigned long prealloc; 486 int ret; 487 488 if (keyring) { 489 ret = __key_link_begin(keyring, key->type, key->description, 490 &prealloc); 491 if (ret < 0) 492 return ret; 493 } 494 495 ret = __key_instantiate_and_link(key, data, datalen, keyring, authkey, 496 &prealloc); 497 498 if (keyring) 499 __key_link_end(keyring, key->type, prealloc); 500 501 return ret; 502 } 503 504 EXPORT_SYMBOL(key_instantiate_and_link); 505 506 /** 507 * key_reject_and_link - Negatively instantiate a key and link it into the keyring. 508 * @key: The key to instantiate. 509 * @timeout: The timeout on the negative key. 510 * @error: The error to return when the key is hit. 511 * @keyring: Keyring to create a link in on success (or NULL). 512 * @authkey: The authorisation token permitting instantiation. 513 * 514 * Negatively instantiate a key that's in the uninstantiated state and, if 515 * successful, set its timeout and stored error and link it in to the 516 * destination keyring if one is supplied. The key and any links to the key 517 * will be automatically garbage collected after the timeout expires. 518 * 519 * Negative keys are used to rate limit repeated request_key() calls by causing 520 * them to return the stored error code (typically ENOKEY) until the negative 521 * key expires. 522 * 523 * If successful, 0 is returned, the authorisation token is revoked and anyone 524 * waiting for the key is woken up. If the key was already instantiated, 525 * -EBUSY will be returned. 526 */ 527 int key_reject_and_link(struct key *key, 528 unsigned timeout, 529 unsigned error, 530 struct key *keyring, 531 struct key *authkey) 532 { 533 unsigned long prealloc; 534 struct timespec now; 535 int ret, awaken, link_ret = 0; 536 537 key_check(key); 538 key_check(keyring); 539 540 awaken = 0; 541 ret = -EBUSY; 542 543 if (keyring) 544 link_ret = __key_link_begin(keyring, key->type, 545 key->description, &prealloc); 546 547 mutex_lock(&key_construction_mutex); 548 549 /* can't instantiate twice */ 550 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) { 551 /* mark the key as being negatively instantiated */ 552 atomic_inc(&key->user->nikeys); 553 set_bit(KEY_FLAG_NEGATIVE, &key->flags); 554 set_bit(KEY_FLAG_INSTANTIATED, &key->flags); 555 key->type_data.reject_error = -error; 556 now = current_kernel_time(); 557 key->expiry = now.tv_sec + timeout; 558 key_schedule_gc(key->expiry + key_gc_delay); 559 560 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) 561 awaken = 1; 562 563 ret = 0; 564 565 /* and link it into the destination keyring */ 566 if (keyring && link_ret == 0) 567 __key_link(keyring, key, &prealloc); 568 569 /* disable the authorisation key */ 570 if (authkey) 571 key_revoke(authkey); 572 } 573 574 mutex_unlock(&key_construction_mutex); 575 576 if (keyring) 577 __key_link_end(keyring, key->type, prealloc); 578 579 /* wake up anyone waiting for a key to be constructed */ 580 if (awaken) 581 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); 582 583 return ret == 0 ? link_ret : ret; 584 } 585 EXPORT_SYMBOL(key_reject_and_link); 586 587 /** 588 * key_put - Discard a reference to a key. 589 * @key: The key to discard a reference from. 590 * 591 * Discard a reference to a key, and when all the references are gone, we 592 * schedule the cleanup task to come and pull it out of the tree in process 593 * context at some later time. 594 */ 595 void key_put(struct key *key) 596 { 597 if (key) { 598 key_check(key); 599 600 if (atomic_dec_and_test(&key->usage)) 601 queue_work(system_nrt_wq, &key_gc_work); 602 } 603 } 604 EXPORT_SYMBOL(key_put); 605 606 /* 607 * Find a key by its serial number. 608 */ 609 struct key *key_lookup(key_serial_t id) 610 { 611 struct rb_node *n; 612 struct key *key; 613 614 spin_lock(&key_serial_lock); 615 616 /* search the tree for the specified key */ 617 n = key_serial_tree.rb_node; 618 while (n) { 619 key = rb_entry(n, struct key, serial_node); 620 621 if (id < key->serial) 622 n = n->rb_left; 623 else if (id > key->serial) 624 n = n->rb_right; 625 else 626 goto found; 627 } 628 629 not_found: 630 key = ERR_PTR(-ENOKEY); 631 goto error; 632 633 found: 634 /* pretend it doesn't exist if it is awaiting deletion */ 635 if (atomic_read(&key->usage) == 0) 636 goto not_found; 637 638 /* this races with key_put(), but that doesn't matter since key_put() 639 * doesn't actually change the key 640 */ 641 atomic_inc(&key->usage); 642 643 error: 644 spin_unlock(&key_serial_lock); 645 return key; 646 } 647 648 /* 649 * Find and lock the specified key type against removal. 650 * 651 * We return with the sem read-locked if successful. If the type wasn't 652 * available -ENOKEY is returned instead. 653 */ 654 struct key_type *key_type_lookup(const char *type) 655 { 656 struct key_type *ktype; 657 658 down_read(&key_types_sem); 659 660 /* look up the key type to see if it's one of the registered kernel 661 * types */ 662 list_for_each_entry(ktype, &key_types_list, link) { 663 if (strcmp(ktype->name, type) == 0) 664 goto found_kernel_type; 665 } 666 667 up_read(&key_types_sem); 668 ktype = ERR_PTR(-ENOKEY); 669 670 found_kernel_type: 671 return ktype; 672 } 673 674 /* 675 * Unlock a key type locked by key_type_lookup(). 676 */ 677 void key_type_put(struct key_type *ktype) 678 { 679 up_read(&key_types_sem); 680 } 681 682 /* 683 * Attempt to update an existing key. 684 * 685 * The key is given to us with an incremented refcount that we need to discard 686 * if we get an error. 687 */ 688 static inline key_ref_t __key_update(key_ref_t key_ref, 689 const void *payload, size_t plen) 690 { 691 struct key *key = key_ref_to_ptr(key_ref); 692 int ret; 693 694 /* need write permission on the key to update it */ 695 ret = key_permission(key_ref, KEY_WRITE); 696 if (ret < 0) 697 goto error; 698 699 ret = -EEXIST; 700 if (!key->type->update) 701 goto error; 702 703 down_write(&key->sem); 704 705 ret = key->type->update(key, payload, plen); 706 if (ret == 0) 707 /* updating a negative key instantiates it */ 708 clear_bit(KEY_FLAG_NEGATIVE, &key->flags); 709 710 up_write(&key->sem); 711 712 if (ret < 0) 713 goto error; 714 out: 715 return key_ref; 716 717 error: 718 key_put(key); 719 key_ref = ERR_PTR(ret); 720 goto out; 721 } 722 723 /** 724 * key_create_or_update - Update or create and instantiate a key. 725 * @keyring_ref: A pointer to the destination keyring with possession flag. 726 * @type: The type of key. 727 * @description: The searchable description for the key. 728 * @payload: The data to use to instantiate or update the key. 729 * @plen: The length of @payload. 730 * @perm: The permissions mask for a new key. 731 * @flags: The quota flags for a new key. 732 * 733 * Search the destination keyring for a key of the same description and if one 734 * is found, update it, otherwise create and instantiate a new one and create a 735 * link to it from that keyring. 736 * 737 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be 738 * concocted. 739 * 740 * Returns a pointer to the new key if successful, -ENODEV if the key type 741 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the 742 * caller isn't permitted to modify the keyring or the LSM did not permit 743 * creation of the key. 744 * 745 * On success, the possession flag from the keyring ref will be tacked on to 746 * the key ref before it is returned. 747 */ 748 key_ref_t key_create_or_update(key_ref_t keyring_ref, 749 const char *type, 750 const char *description, 751 const void *payload, 752 size_t plen, 753 key_perm_t perm, 754 unsigned long flags) 755 { 756 unsigned long prealloc; 757 const struct cred *cred = current_cred(); 758 struct key_type *ktype; 759 struct key *keyring, *key = NULL; 760 key_ref_t key_ref; 761 int ret; 762 763 /* look up the key type to see if it's one of the registered kernel 764 * types */ 765 ktype = key_type_lookup(type); 766 if (IS_ERR(ktype)) { 767 key_ref = ERR_PTR(-ENODEV); 768 goto error; 769 } 770 771 key_ref = ERR_PTR(-EINVAL); 772 if (!ktype->match || !ktype->instantiate) 773 goto error_2; 774 775 keyring = key_ref_to_ptr(keyring_ref); 776 777 key_check(keyring); 778 779 key_ref = ERR_PTR(-ENOTDIR); 780 if (keyring->type != &key_type_keyring) 781 goto error_2; 782 783 ret = __key_link_begin(keyring, ktype, description, &prealloc); 784 if (ret < 0) 785 goto error_2; 786 787 /* if we're going to allocate a new key, we're going to have 788 * to modify the keyring */ 789 ret = key_permission(keyring_ref, KEY_WRITE); 790 if (ret < 0) { 791 key_ref = ERR_PTR(ret); 792 goto error_3; 793 } 794 795 /* if it's possible to update this type of key, search for an existing 796 * key of the same type and description in the destination keyring and 797 * update that instead if possible 798 */ 799 if (ktype->update) { 800 key_ref = __keyring_search_one(keyring_ref, ktype, description, 801 0); 802 if (!IS_ERR(key_ref)) 803 goto found_matching_key; 804 } 805 806 /* if the client doesn't provide, decide on the permissions we want */ 807 if (perm == KEY_PERM_UNDEF) { 808 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR; 809 perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR; 810 811 if (ktype->read) 812 perm |= KEY_POS_READ | KEY_USR_READ; 813 814 if (ktype == &key_type_keyring || ktype->update) 815 perm |= KEY_USR_WRITE; 816 } 817 818 /* allocate a new key */ 819 key = key_alloc(ktype, description, cred->fsuid, cred->fsgid, cred, 820 perm, flags); 821 if (IS_ERR(key)) { 822 key_ref = ERR_CAST(key); 823 goto error_3; 824 } 825 826 /* instantiate it and link it into the target keyring */ 827 ret = __key_instantiate_and_link(key, payload, plen, keyring, NULL, 828 &prealloc); 829 if (ret < 0) { 830 key_put(key); 831 key_ref = ERR_PTR(ret); 832 goto error_3; 833 } 834 835 key_ref = make_key_ref(key, is_key_possessed(keyring_ref)); 836 837 error_3: 838 __key_link_end(keyring, ktype, prealloc); 839 error_2: 840 key_type_put(ktype); 841 error: 842 return key_ref; 843 844 found_matching_key: 845 /* we found a matching key, so we're going to try to update it 846 * - we can drop the locks first as we have the key pinned 847 */ 848 __key_link_end(keyring, ktype, prealloc); 849 key_type_put(ktype); 850 851 key_ref = __key_update(key_ref, payload, plen); 852 goto error; 853 } 854 EXPORT_SYMBOL(key_create_or_update); 855 856 /** 857 * key_update - Update a key's contents. 858 * @key_ref: The pointer (plus possession flag) to the key. 859 * @payload: The data to be used to update the key. 860 * @plen: The length of @payload. 861 * 862 * Attempt to update the contents of a key with the given payload data. The 863 * caller must be granted Write permission on the key. Negative keys can be 864 * instantiated by this method. 865 * 866 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key 867 * type does not support updating. The key type may return other errors. 868 */ 869 int key_update(key_ref_t key_ref, const void *payload, size_t plen) 870 { 871 struct key *key = key_ref_to_ptr(key_ref); 872 int ret; 873 874 key_check(key); 875 876 /* the key must be writable */ 877 ret = key_permission(key_ref, KEY_WRITE); 878 if (ret < 0) 879 goto error; 880 881 /* attempt to update it if supported */ 882 ret = -EOPNOTSUPP; 883 if (key->type->update) { 884 down_write(&key->sem); 885 886 ret = key->type->update(key, payload, plen); 887 if (ret == 0) 888 /* updating a negative key instantiates it */ 889 clear_bit(KEY_FLAG_NEGATIVE, &key->flags); 890 891 up_write(&key->sem); 892 } 893 894 error: 895 return ret; 896 } 897 EXPORT_SYMBOL(key_update); 898 899 /** 900 * key_revoke - Revoke a key. 901 * @key: The key to be revoked. 902 * 903 * Mark a key as being revoked and ask the type to free up its resources. The 904 * revocation timeout is set and the key and all its links will be 905 * automatically garbage collected after key_gc_delay amount of time if they 906 * are not manually dealt with first. 907 */ 908 void key_revoke(struct key *key) 909 { 910 struct timespec now; 911 time_t time; 912 913 key_check(key); 914 915 /* make sure no one's trying to change or use the key when we mark it 916 * - we tell lockdep that we might nest because we might be revoking an 917 * authorisation key whilst holding the sem on a key we've just 918 * instantiated 919 */ 920 down_write_nested(&key->sem, 1); 921 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) && 922 key->type->revoke) 923 key->type->revoke(key); 924 925 /* set the death time to no more than the expiry time */ 926 now = current_kernel_time(); 927 time = now.tv_sec; 928 if (key->revoked_at == 0 || key->revoked_at > time) { 929 key->revoked_at = time; 930 key_schedule_gc(key->revoked_at + key_gc_delay); 931 } 932 933 up_write(&key->sem); 934 } 935 EXPORT_SYMBOL(key_revoke); 936 937 /** 938 * register_key_type - Register a type of key. 939 * @ktype: The new key type. 940 * 941 * Register a new key type. 942 * 943 * Returns 0 on success or -EEXIST if a type of this name already exists. 944 */ 945 int register_key_type(struct key_type *ktype) 946 { 947 struct key_type *p; 948 int ret; 949 950 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class)); 951 952 ret = -EEXIST; 953 down_write(&key_types_sem); 954 955 /* disallow key types with the same name */ 956 list_for_each_entry(p, &key_types_list, link) { 957 if (strcmp(p->name, ktype->name) == 0) 958 goto out; 959 } 960 961 /* store the type */ 962 list_add(&ktype->link, &key_types_list); 963 ret = 0; 964 965 out: 966 up_write(&key_types_sem); 967 return ret; 968 } 969 EXPORT_SYMBOL(register_key_type); 970 971 /** 972 * unregister_key_type - Unregister a type of key. 973 * @ktype: The key type. 974 * 975 * Unregister a key type and mark all the extant keys of this type as dead. 976 * Those keys of this type are then destroyed to get rid of their payloads and 977 * they and their links will be garbage collected as soon as possible. 978 */ 979 void unregister_key_type(struct key_type *ktype) 980 { 981 down_write(&key_types_sem); 982 list_del_init(&ktype->link); 983 downgrade_write(&key_types_sem); 984 key_gc_keytype(ktype); 985 up_read(&key_types_sem); 986 } 987 EXPORT_SYMBOL(unregister_key_type); 988 989 /* 990 * Initialise the key management state. 991 */ 992 void __init key_init(void) 993 { 994 /* allocate a slab in which we can store keys */ 995 key_jar = kmem_cache_create("key_jar", sizeof(struct key), 996 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 997 998 /* add the special key types */ 999 list_add_tail(&key_type_keyring.link, &key_types_list); 1000 list_add_tail(&key_type_dead.link, &key_types_list); 1001 list_add_tail(&key_type_user.link, &key_types_list); 1002 list_add_tail(&key_type_logon.link, &key_types_list); 1003 1004 /* record the root user tracking */ 1005 rb_link_node(&root_key_user.node, 1006 NULL, 1007 &key_user_tree.rb_node); 1008 1009 rb_insert_color(&root_key_user.node, 1010 &key_user_tree); 1011 } 1012