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, **p; 58 59 try_again: 60 parent = NULL; 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 refcount_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 refcount_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 (refcount_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 * @restrict_link: Optional link restriction for new keyrings. 205 * 206 * Allocate a key of the specified type with the attributes given. The key is 207 * returned in an uninstantiated state and the caller needs to instantiate the 208 * key before returning. 209 * 210 * The restrict_link structure (if not NULL) will be freed when the 211 * keyring is destroyed, so it must be dynamically allocated. 212 * 213 * The user's key count quota is updated to reflect the creation of the key and 214 * the user's key data quota has the default for the key type reserved. The 215 * instantiation function should amend this as necessary. If insufficient 216 * quota is available, -EDQUOT will be returned. 217 * 218 * The LSM security modules can prevent a key being created, in which case 219 * -EACCES will be returned. 220 * 221 * Returns a pointer to the new key if successful and an error code otherwise. 222 * 223 * Note that the caller needs to ensure the key type isn't uninstantiated. 224 * Internally this can be done by locking key_types_sem. Externally, this can 225 * be done by either never unregistering the key type, or making sure 226 * key_alloc() calls don't race with module unloading. 227 */ 228 struct key *key_alloc(struct key_type *type, const char *desc, 229 kuid_t uid, kgid_t gid, const struct cred *cred, 230 key_perm_t perm, unsigned long flags, 231 struct key_restriction *restrict_link) 232 { 233 struct key_user *user = NULL; 234 struct key *key; 235 size_t desclen, quotalen; 236 int ret; 237 238 key = ERR_PTR(-EINVAL); 239 if (!desc || !*desc) 240 goto error; 241 242 if (type->vet_description) { 243 ret = type->vet_description(desc); 244 if (ret < 0) { 245 key = ERR_PTR(ret); 246 goto error; 247 } 248 } 249 250 desclen = strlen(desc); 251 quotalen = desclen + 1 + type->def_datalen; 252 253 /* get hold of the key tracking for this user */ 254 user = key_user_lookup(uid); 255 if (!user) 256 goto no_memory_1; 257 258 /* check that the user's quota permits allocation of another key and 259 * its description */ 260 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { 261 unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ? 262 key_quota_root_maxkeys : key_quota_maxkeys; 263 unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ? 264 key_quota_root_maxbytes : key_quota_maxbytes; 265 266 spin_lock(&user->lock); 267 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) { 268 if (user->qnkeys + 1 >= maxkeys || 269 user->qnbytes + quotalen >= maxbytes || 270 user->qnbytes + quotalen < user->qnbytes) 271 goto no_quota; 272 } 273 274 user->qnkeys++; 275 user->qnbytes += quotalen; 276 spin_unlock(&user->lock); 277 } 278 279 /* allocate and initialise the key and its description */ 280 key = kmem_cache_zalloc(key_jar, GFP_KERNEL); 281 if (!key) 282 goto no_memory_2; 283 284 key->index_key.desc_len = desclen; 285 key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL); 286 if (!key->index_key.description) 287 goto no_memory_3; 288 289 refcount_set(&key->usage, 1); 290 init_rwsem(&key->sem); 291 lockdep_set_class(&key->sem, &type->lock_class); 292 key->index_key.type = type; 293 key->user = user; 294 key->quotalen = quotalen; 295 key->datalen = type->def_datalen; 296 key->uid = uid; 297 key->gid = gid; 298 key->perm = perm; 299 key->restrict_link = restrict_link; 300 301 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) 302 key->flags |= 1 << KEY_FLAG_IN_QUOTA; 303 if (flags & KEY_ALLOC_BUILT_IN) 304 key->flags |= 1 << KEY_FLAG_BUILTIN; 305 if (flags & KEY_ALLOC_UID_KEYRING) 306 key->flags |= 1 << KEY_FLAG_UID_KEYRING; 307 308 #ifdef KEY_DEBUGGING 309 key->magic = KEY_DEBUG_MAGIC; 310 #endif 311 312 /* let the security module know about the key */ 313 ret = security_key_alloc(key, cred, flags); 314 if (ret < 0) 315 goto security_error; 316 317 /* publish the key by giving it a serial number */ 318 atomic_inc(&user->nkeys); 319 key_alloc_serial(key); 320 321 error: 322 return key; 323 324 security_error: 325 kfree(key->description); 326 kmem_cache_free(key_jar, key); 327 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { 328 spin_lock(&user->lock); 329 user->qnkeys--; 330 user->qnbytes -= quotalen; 331 spin_unlock(&user->lock); 332 } 333 key_user_put(user); 334 key = ERR_PTR(ret); 335 goto error; 336 337 no_memory_3: 338 kmem_cache_free(key_jar, key); 339 no_memory_2: 340 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) { 341 spin_lock(&user->lock); 342 user->qnkeys--; 343 user->qnbytes -= quotalen; 344 spin_unlock(&user->lock); 345 } 346 key_user_put(user); 347 no_memory_1: 348 key = ERR_PTR(-ENOMEM); 349 goto error; 350 351 no_quota: 352 spin_unlock(&user->lock); 353 key_user_put(user); 354 key = ERR_PTR(-EDQUOT); 355 goto error; 356 } 357 EXPORT_SYMBOL(key_alloc); 358 359 /** 360 * key_payload_reserve - Adjust data quota reservation for the key's payload 361 * @key: The key to make the reservation for. 362 * @datalen: The amount of data payload the caller now wants. 363 * 364 * Adjust the amount of the owning user's key data quota that a key reserves. 365 * If the amount is increased, then -EDQUOT may be returned if there isn't 366 * enough free quota available. 367 * 368 * If successful, 0 is returned. 369 */ 370 int key_payload_reserve(struct key *key, size_t datalen) 371 { 372 int delta = (int)datalen - key->datalen; 373 int ret = 0; 374 375 key_check(key); 376 377 /* contemplate the quota adjustment */ 378 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) { 379 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ? 380 key_quota_root_maxbytes : key_quota_maxbytes; 381 382 spin_lock(&key->user->lock); 383 384 if (delta > 0 && 385 (key->user->qnbytes + delta >= maxbytes || 386 key->user->qnbytes + delta < key->user->qnbytes)) { 387 ret = -EDQUOT; 388 } 389 else { 390 key->user->qnbytes += delta; 391 key->quotalen += delta; 392 } 393 spin_unlock(&key->user->lock); 394 } 395 396 /* change the recorded data length if that didn't generate an error */ 397 if (ret == 0) 398 key->datalen = datalen; 399 400 return ret; 401 } 402 EXPORT_SYMBOL(key_payload_reserve); 403 404 /* 405 * Change the key state to being instantiated. 406 */ 407 static void mark_key_instantiated(struct key *key, int reject_error) 408 { 409 /* Commit the payload before setting the state; barrier versus 410 * key_read_state(). 411 */ 412 smp_store_release(&key->state, 413 (reject_error < 0) ? reject_error : KEY_IS_POSITIVE); 414 } 415 416 /* 417 * Instantiate a key and link it into the target keyring atomically. Must be 418 * called with the target keyring's semaphore writelocked. The target key's 419 * semaphore need not be locked as instantiation is serialised by 420 * key_construction_mutex. 421 */ 422 static int __key_instantiate_and_link(struct key *key, 423 struct key_preparsed_payload *prep, 424 struct key *keyring, 425 struct key *authkey, 426 struct assoc_array_edit **_edit) 427 { 428 int ret, awaken; 429 430 key_check(key); 431 key_check(keyring); 432 433 awaken = 0; 434 ret = -EBUSY; 435 436 mutex_lock(&key_construction_mutex); 437 438 /* can't instantiate twice */ 439 if (key->state == KEY_IS_UNINSTANTIATED) { 440 /* instantiate the key */ 441 ret = key->type->instantiate(key, prep); 442 443 if (ret == 0) { 444 /* mark the key as being instantiated */ 445 atomic_inc(&key->user->nikeys); 446 mark_key_instantiated(key, 0); 447 448 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) 449 awaken = 1; 450 451 /* and link it into the destination keyring */ 452 if (keyring) { 453 if (test_bit(KEY_FLAG_KEEP, &keyring->flags)) 454 set_bit(KEY_FLAG_KEEP, &key->flags); 455 456 __key_link(key, _edit); 457 } 458 459 /* disable the authorisation key */ 460 if (authkey) 461 key_revoke(authkey); 462 463 if (prep->expiry != TIME_T_MAX) { 464 key->expiry = prep->expiry; 465 key_schedule_gc(prep->expiry + key_gc_delay); 466 } 467 } 468 } 469 470 mutex_unlock(&key_construction_mutex); 471 472 /* wake up anyone waiting for a key to be constructed */ 473 if (awaken) 474 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); 475 476 return ret; 477 } 478 479 /** 480 * key_instantiate_and_link - Instantiate a key and link it into the keyring. 481 * @key: The key to instantiate. 482 * @data: The data to use to instantiate the keyring. 483 * @datalen: The length of @data. 484 * @keyring: Keyring to create a link in on success (or NULL). 485 * @authkey: The authorisation token permitting instantiation. 486 * 487 * Instantiate a key that's in the uninstantiated state using the provided data 488 * and, if successful, link it in to the destination keyring if one is 489 * supplied. 490 * 491 * If successful, 0 is returned, the authorisation token is revoked and anyone 492 * waiting for the key is woken up. If the key was already instantiated, 493 * -EBUSY will be returned. 494 */ 495 int key_instantiate_and_link(struct key *key, 496 const void *data, 497 size_t datalen, 498 struct key *keyring, 499 struct key *authkey) 500 { 501 struct key_preparsed_payload prep; 502 struct assoc_array_edit *edit; 503 int ret; 504 505 memset(&prep, 0, sizeof(prep)); 506 prep.data = data; 507 prep.datalen = datalen; 508 prep.quotalen = key->type->def_datalen; 509 prep.expiry = TIME_T_MAX; 510 if (key->type->preparse) { 511 ret = key->type->preparse(&prep); 512 if (ret < 0) 513 goto error; 514 } 515 516 if (keyring) { 517 ret = __key_link_begin(keyring, &key->index_key, &edit); 518 if (ret < 0) 519 goto error; 520 521 if (keyring->restrict_link && keyring->restrict_link->check) { 522 struct key_restriction *keyres = keyring->restrict_link; 523 524 ret = keyres->check(keyring, key->type, &prep.payload, 525 keyres->key); 526 if (ret < 0) 527 goto error_link_end; 528 } 529 } 530 531 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit); 532 533 error_link_end: 534 if (keyring) 535 __key_link_end(keyring, &key->index_key, edit); 536 537 error: 538 if (key->type->preparse) 539 key->type->free_preparse(&prep); 540 return ret; 541 } 542 543 EXPORT_SYMBOL(key_instantiate_and_link); 544 545 /** 546 * key_reject_and_link - Negatively instantiate a key and link it into the keyring. 547 * @key: The key to instantiate. 548 * @timeout: The timeout on the negative key. 549 * @error: The error to return when the key is hit. 550 * @keyring: Keyring to create a link in on success (or NULL). 551 * @authkey: The authorisation token permitting instantiation. 552 * 553 * Negatively instantiate a key that's in the uninstantiated state and, if 554 * successful, set its timeout and stored error and link it in to the 555 * destination keyring if one is supplied. The key and any links to the key 556 * will be automatically garbage collected after the timeout expires. 557 * 558 * Negative keys are used to rate limit repeated request_key() calls by causing 559 * them to return the stored error code (typically ENOKEY) until the negative 560 * key expires. 561 * 562 * If successful, 0 is returned, the authorisation token is revoked and anyone 563 * waiting for the key is woken up. If the key was already instantiated, 564 * -EBUSY will be returned. 565 */ 566 int key_reject_and_link(struct key *key, 567 unsigned timeout, 568 unsigned error, 569 struct key *keyring, 570 struct key *authkey) 571 { 572 struct assoc_array_edit *edit; 573 struct timespec now; 574 int ret, awaken, link_ret = 0; 575 576 key_check(key); 577 key_check(keyring); 578 579 awaken = 0; 580 ret = -EBUSY; 581 582 if (keyring) { 583 if (keyring->restrict_link) 584 return -EPERM; 585 586 link_ret = __key_link_begin(keyring, &key->index_key, &edit); 587 } 588 589 mutex_lock(&key_construction_mutex); 590 591 /* can't instantiate twice */ 592 if (key->state == KEY_IS_UNINSTANTIATED) { 593 /* mark the key as being negatively instantiated */ 594 atomic_inc(&key->user->nikeys); 595 mark_key_instantiated(key, -error); 596 now = current_kernel_time(); 597 key->expiry = now.tv_sec + timeout; 598 key_schedule_gc(key->expiry + key_gc_delay); 599 600 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) 601 awaken = 1; 602 603 ret = 0; 604 605 /* and link it into the destination keyring */ 606 if (keyring && link_ret == 0) 607 __key_link(key, &edit); 608 609 /* disable the authorisation key */ 610 if (authkey) 611 key_revoke(authkey); 612 } 613 614 mutex_unlock(&key_construction_mutex); 615 616 if (keyring && link_ret == 0) 617 __key_link_end(keyring, &key->index_key, edit); 618 619 /* wake up anyone waiting for a key to be constructed */ 620 if (awaken) 621 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT); 622 623 return ret == 0 ? link_ret : ret; 624 } 625 EXPORT_SYMBOL(key_reject_and_link); 626 627 /** 628 * key_put - Discard a reference to a key. 629 * @key: The key to discard a reference from. 630 * 631 * Discard a reference to a key, and when all the references are gone, we 632 * schedule the cleanup task to come and pull it out of the tree in process 633 * context at some later time. 634 */ 635 void key_put(struct key *key) 636 { 637 if (key) { 638 key_check(key); 639 640 if (refcount_dec_and_test(&key->usage)) 641 schedule_work(&key_gc_work); 642 } 643 } 644 EXPORT_SYMBOL(key_put); 645 646 /* 647 * Find a key by its serial number. 648 */ 649 struct key *key_lookup(key_serial_t id) 650 { 651 struct rb_node *n; 652 struct key *key; 653 654 spin_lock(&key_serial_lock); 655 656 /* search the tree for the specified key */ 657 n = key_serial_tree.rb_node; 658 while (n) { 659 key = rb_entry(n, struct key, serial_node); 660 661 if (id < key->serial) 662 n = n->rb_left; 663 else if (id > key->serial) 664 n = n->rb_right; 665 else 666 goto found; 667 } 668 669 not_found: 670 key = ERR_PTR(-ENOKEY); 671 goto error; 672 673 found: 674 /* A key is allowed to be looked up only if someone still owns a 675 * reference to it - otherwise it's awaiting the gc. 676 */ 677 if (!refcount_inc_not_zero(&key->usage)) 678 goto not_found; 679 680 error: 681 spin_unlock(&key_serial_lock); 682 return key; 683 } 684 685 /* 686 * Find and lock the specified key type against removal. 687 * 688 * We return with the sem read-locked if successful. If the type wasn't 689 * available -ENOKEY is returned instead. 690 */ 691 struct key_type *key_type_lookup(const char *type) 692 { 693 struct key_type *ktype; 694 695 down_read(&key_types_sem); 696 697 /* look up the key type to see if it's one of the registered kernel 698 * types */ 699 list_for_each_entry(ktype, &key_types_list, link) { 700 if (strcmp(ktype->name, type) == 0) 701 goto found_kernel_type; 702 } 703 704 up_read(&key_types_sem); 705 ktype = ERR_PTR(-ENOKEY); 706 707 found_kernel_type: 708 return ktype; 709 } 710 711 void key_set_timeout(struct key *key, unsigned timeout) 712 { 713 struct timespec now; 714 time_t expiry = 0; 715 716 /* make the changes with the locks held to prevent races */ 717 down_write(&key->sem); 718 719 if (timeout > 0) { 720 now = current_kernel_time(); 721 expiry = now.tv_sec + timeout; 722 } 723 724 key->expiry = expiry; 725 key_schedule_gc(key->expiry + key_gc_delay); 726 727 up_write(&key->sem); 728 } 729 EXPORT_SYMBOL_GPL(key_set_timeout); 730 731 /* 732 * Unlock a key type locked by key_type_lookup(). 733 */ 734 void key_type_put(struct key_type *ktype) 735 { 736 up_read(&key_types_sem); 737 } 738 739 /* 740 * Attempt to update an existing key. 741 * 742 * The key is given to us with an incremented refcount that we need to discard 743 * if we get an error. 744 */ 745 static inline key_ref_t __key_update(key_ref_t key_ref, 746 struct key_preparsed_payload *prep) 747 { 748 struct key *key = key_ref_to_ptr(key_ref); 749 int ret; 750 751 /* need write permission on the key to update it */ 752 ret = key_permission(key_ref, KEY_NEED_WRITE); 753 if (ret < 0) 754 goto error; 755 756 ret = -EEXIST; 757 if (!key->type->update) 758 goto error; 759 760 down_write(&key->sem); 761 762 ret = key->type->update(key, prep); 763 if (ret == 0) 764 /* Updating a negative key positively instantiates it */ 765 mark_key_instantiated(key, 0); 766 767 up_write(&key->sem); 768 769 if (ret < 0) 770 goto error; 771 out: 772 return key_ref; 773 774 error: 775 key_put(key); 776 key_ref = ERR_PTR(ret); 777 goto out; 778 } 779 780 /** 781 * key_create_or_update - Update or create and instantiate a key. 782 * @keyring_ref: A pointer to the destination keyring with possession flag. 783 * @type: The type of key. 784 * @description: The searchable description for the key. 785 * @payload: The data to use to instantiate or update the key. 786 * @plen: The length of @payload. 787 * @perm: The permissions mask for a new key. 788 * @flags: The quota flags for a new key. 789 * 790 * Search the destination keyring for a key of the same description and if one 791 * is found, update it, otherwise create and instantiate a new one and create a 792 * link to it from that keyring. 793 * 794 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be 795 * concocted. 796 * 797 * Returns a pointer to the new key if successful, -ENODEV if the key type 798 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the 799 * caller isn't permitted to modify the keyring or the LSM did not permit 800 * creation of the key. 801 * 802 * On success, the possession flag from the keyring ref will be tacked on to 803 * the key ref before it is returned. 804 */ 805 key_ref_t key_create_or_update(key_ref_t keyring_ref, 806 const char *type, 807 const char *description, 808 const void *payload, 809 size_t plen, 810 key_perm_t perm, 811 unsigned long flags) 812 { 813 struct keyring_index_key index_key = { 814 .description = description, 815 }; 816 struct key_preparsed_payload prep; 817 struct assoc_array_edit *edit; 818 const struct cred *cred = current_cred(); 819 struct key *keyring, *key = NULL; 820 key_ref_t key_ref; 821 int ret; 822 struct key_restriction *restrict_link = NULL; 823 824 /* look up the key type to see if it's one of the registered kernel 825 * types */ 826 index_key.type = key_type_lookup(type); 827 if (IS_ERR(index_key.type)) { 828 key_ref = ERR_PTR(-ENODEV); 829 goto error; 830 } 831 832 key_ref = ERR_PTR(-EINVAL); 833 if (!index_key.type->instantiate || 834 (!index_key.description && !index_key.type->preparse)) 835 goto error_put_type; 836 837 keyring = key_ref_to_ptr(keyring_ref); 838 839 key_check(keyring); 840 841 key_ref = ERR_PTR(-EPERM); 842 if (!(flags & KEY_ALLOC_BYPASS_RESTRICTION)) 843 restrict_link = keyring->restrict_link; 844 845 key_ref = ERR_PTR(-ENOTDIR); 846 if (keyring->type != &key_type_keyring) 847 goto error_put_type; 848 849 memset(&prep, 0, sizeof(prep)); 850 prep.data = payload; 851 prep.datalen = plen; 852 prep.quotalen = index_key.type->def_datalen; 853 prep.expiry = TIME_T_MAX; 854 if (index_key.type->preparse) { 855 ret = index_key.type->preparse(&prep); 856 if (ret < 0) { 857 key_ref = ERR_PTR(ret); 858 goto error_free_prep; 859 } 860 if (!index_key.description) 861 index_key.description = prep.description; 862 key_ref = ERR_PTR(-EINVAL); 863 if (!index_key.description) 864 goto error_free_prep; 865 } 866 index_key.desc_len = strlen(index_key.description); 867 868 ret = __key_link_begin(keyring, &index_key, &edit); 869 if (ret < 0) { 870 key_ref = ERR_PTR(ret); 871 goto error_free_prep; 872 } 873 874 if (restrict_link && restrict_link->check) { 875 ret = restrict_link->check(keyring, index_key.type, 876 &prep.payload, restrict_link->key); 877 if (ret < 0) { 878 key_ref = ERR_PTR(ret); 879 goto error_link_end; 880 } 881 } 882 883 /* if we're going to allocate a new key, we're going to have 884 * to modify the keyring */ 885 ret = key_permission(keyring_ref, KEY_NEED_WRITE); 886 if (ret < 0) { 887 key_ref = ERR_PTR(ret); 888 goto error_link_end; 889 } 890 891 /* if it's possible to update this type of key, search for an existing 892 * key of the same type and description in the destination keyring and 893 * update that instead if possible 894 */ 895 if (index_key.type->update) { 896 key_ref = find_key_to_update(keyring_ref, &index_key); 897 if (key_ref) 898 goto found_matching_key; 899 } 900 901 /* if the client doesn't provide, decide on the permissions we want */ 902 if (perm == KEY_PERM_UNDEF) { 903 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR; 904 perm |= KEY_USR_VIEW; 905 906 if (index_key.type->read) 907 perm |= KEY_POS_READ; 908 909 if (index_key.type == &key_type_keyring || 910 index_key.type->update) 911 perm |= KEY_POS_WRITE; 912 } 913 914 /* allocate a new key */ 915 key = key_alloc(index_key.type, index_key.description, 916 cred->fsuid, cred->fsgid, cred, perm, flags, NULL); 917 if (IS_ERR(key)) { 918 key_ref = ERR_CAST(key); 919 goto error_link_end; 920 } 921 922 /* instantiate it and link it into the target keyring */ 923 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit); 924 if (ret < 0) { 925 key_put(key); 926 key_ref = ERR_PTR(ret); 927 goto error_link_end; 928 } 929 930 key_ref = make_key_ref(key, is_key_possessed(keyring_ref)); 931 932 error_link_end: 933 __key_link_end(keyring, &index_key, edit); 934 error_free_prep: 935 if (index_key.type->preparse) 936 index_key.type->free_preparse(&prep); 937 error_put_type: 938 key_type_put(index_key.type); 939 error: 940 return key_ref; 941 942 found_matching_key: 943 /* we found a matching key, so we're going to try to update it 944 * - we can drop the locks first as we have the key pinned 945 */ 946 __key_link_end(keyring, &index_key, edit); 947 948 key = key_ref_to_ptr(key_ref); 949 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) { 950 ret = wait_for_key_construction(key, true); 951 if (ret < 0) { 952 key_ref_put(key_ref); 953 key_ref = ERR_PTR(ret); 954 goto error_free_prep; 955 } 956 } 957 958 key_ref = __key_update(key_ref, &prep); 959 goto error_free_prep; 960 } 961 EXPORT_SYMBOL(key_create_or_update); 962 963 /** 964 * key_update - Update a key's contents. 965 * @key_ref: The pointer (plus possession flag) to the key. 966 * @payload: The data to be used to update the key. 967 * @plen: The length of @payload. 968 * 969 * Attempt to update the contents of a key with the given payload data. The 970 * caller must be granted Write permission on the key. Negative keys can be 971 * instantiated by this method. 972 * 973 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key 974 * type does not support updating. The key type may return other errors. 975 */ 976 int key_update(key_ref_t key_ref, const void *payload, size_t plen) 977 { 978 struct key_preparsed_payload prep; 979 struct key *key = key_ref_to_ptr(key_ref); 980 int ret; 981 982 key_check(key); 983 984 /* the key must be writable */ 985 ret = key_permission(key_ref, KEY_NEED_WRITE); 986 if (ret < 0) 987 return ret; 988 989 /* attempt to update it if supported */ 990 if (!key->type->update) 991 return -EOPNOTSUPP; 992 993 memset(&prep, 0, sizeof(prep)); 994 prep.data = payload; 995 prep.datalen = plen; 996 prep.quotalen = key->type->def_datalen; 997 prep.expiry = TIME_T_MAX; 998 if (key->type->preparse) { 999 ret = key->type->preparse(&prep); 1000 if (ret < 0) 1001 goto error; 1002 } 1003 1004 down_write(&key->sem); 1005 1006 ret = key->type->update(key, &prep); 1007 if (ret == 0) 1008 /* Updating a negative key positively instantiates it */ 1009 mark_key_instantiated(key, 0); 1010 1011 up_write(&key->sem); 1012 1013 error: 1014 if (key->type->preparse) 1015 key->type->free_preparse(&prep); 1016 return ret; 1017 } 1018 EXPORT_SYMBOL(key_update); 1019 1020 /** 1021 * key_revoke - Revoke a key. 1022 * @key: The key to be revoked. 1023 * 1024 * Mark a key as being revoked and ask the type to free up its resources. The 1025 * revocation timeout is set and the key and all its links will be 1026 * automatically garbage collected after key_gc_delay amount of time if they 1027 * are not manually dealt with first. 1028 */ 1029 void key_revoke(struct key *key) 1030 { 1031 struct timespec now; 1032 time_t time; 1033 1034 key_check(key); 1035 1036 /* make sure no one's trying to change or use the key when we mark it 1037 * - we tell lockdep that we might nest because we might be revoking an 1038 * authorisation key whilst holding the sem on a key we've just 1039 * instantiated 1040 */ 1041 down_write_nested(&key->sem, 1); 1042 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) && 1043 key->type->revoke) 1044 key->type->revoke(key); 1045 1046 /* set the death time to no more than the expiry time */ 1047 now = current_kernel_time(); 1048 time = now.tv_sec; 1049 if (key->revoked_at == 0 || key->revoked_at > time) { 1050 key->revoked_at = time; 1051 key_schedule_gc(key->revoked_at + key_gc_delay); 1052 } 1053 1054 up_write(&key->sem); 1055 } 1056 EXPORT_SYMBOL(key_revoke); 1057 1058 /** 1059 * key_invalidate - Invalidate a key. 1060 * @key: The key to be invalidated. 1061 * 1062 * Mark a key as being invalidated and have it cleaned up immediately. The key 1063 * is ignored by all searches and other operations from this point. 1064 */ 1065 void key_invalidate(struct key *key) 1066 { 1067 kenter("%d", key_serial(key)); 1068 1069 key_check(key); 1070 1071 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) { 1072 down_write_nested(&key->sem, 1); 1073 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags)) 1074 key_schedule_gc_links(); 1075 up_write(&key->sem); 1076 } 1077 } 1078 EXPORT_SYMBOL(key_invalidate); 1079 1080 /** 1081 * generic_key_instantiate - Simple instantiation of a key from preparsed data 1082 * @key: The key to be instantiated 1083 * @prep: The preparsed data to load. 1084 * 1085 * Instantiate a key from preparsed data. We assume we can just copy the data 1086 * in directly and clear the old pointers. 1087 * 1088 * This can be pointed to directly by the key type instantiate op pointer. 1089 */ 1090 int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep) 1091 { 1092 int ret; 1093 1094 pr_devel("==>%s()\n", __func__); 1095 1096 ret = key_payload_reserve(key, prep->quotalen); 1097 if (ret == 0) { 1098 rcu_assign_keypointer(key, prep->payload.data[0]); 1099 key->payload.data[1] = prep->payload.data[1]; 1100 key->payload.data[2] = prep->payload.data[2]; 1101 key->payload.data[3] = prep->payload.data[3]; 1102 prep->payload.data[0] = NULL; 1103 prep->payload.data[1] = NULL; 1104 prep->payload.data[2] = NULL; 1105 prep->payload.data[3] = NULL; 1106 } 1107 pr_devel("<==%s() = %d\n", __func__, ret); 1108 return ret; 1109 } 1110 EXPORT_SYMBOL(generic_key_instantiate); 1111 1112 /** 1113 * register_key_type - Register a type of key. 1114 * @ktype: The new key type. 1115 * 1116 * Register a new key type. 1117 * 1118 * Returns 0 on success or -EEXIST if a type of this name already exists. 1119 */ 1120 int register_key_type(struct key_type *ktype) 1121 { 1122 struct key_type *p; 1123 int ret; 1124 1125 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class)); 1126 1127 ret = -EEXIST; 1128 down_write(&key_types_sem); 1129 1130 /* disallow key types with the same name */ 1131 list_for_each_entry(p, &key_types_list, link) { 1132 if (strcmp(p->name, ktype->name) == 0) 1133 goto out; 1134 } 1135 1136 /* store the type */ 1137 list_add(&ktype->link, &key_types_list); 1138 1139 pr_notice("Key type %s registered\n", ktype->name); 1140 ret = 0; 1141 1142 out: 1143 up_write(&key_types_sem); 1144 return ret; 1145 } 1146 EXPORT_SYMBOL(register_key_type); 1147 1148 /** 1149 * unregister_key_type - Unregister a type of key. 1150 * @ktype: The key type. 1151 * 1152 * Unregister a key type and mark all the extant keys of this type as dead. 1153 * Those keys of this type are then destroyed to get rid of their payloads and 1154 * they and their links will be garbage collected as soon as possible. 1155 */ 1156 void unregister_key_type(struct key_type *ktype) 1157 { 1158 down_write(&key_types_sem); 1159 list_del_init(&ktype->link); 1160 downgrade_write(&key_types_sem); 1161 key_gc_keytype(ktype); 1162 pr_notice("Key type %s unregistered\n", ktype->name); 1163 up_read(&key_types_sem); 1164 } 1165 EXPORT_SYMBOL(unregister_key_type); 1166 1167 /* 1168 * Initialise the key management state. 1169 */ 1170 void __init key_init(void) 1171 { 1172 /* allocate a slab in which we can store keys */ 1173 key_jar = kmem_cache_create("key_jar", sizeof(struct key), 1174 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL); 1175 1176 /* add the special key types */ 1177 list_add_tail(&key_type_keyring.link, &key_types_list); 1178 list_add_tail(&key_type_dead.link, &key_types_list); 1179 list_add_tail(&key_type_user.link, &key_types_list); 1180 list_add_tail(&key_type_logon.link, &key_types_list); 1181 1182 /* record the root user tracking */ 1183 rb_link_node(&root_key_user.node, 1184 NULL, 1185 &key_user_tree.rb_node); 1186 1187 rb_insert_color(&root_key_user.node, 1188 &key_user_tree); 1189 } 1190