1 /* Basic authentication token and access key management
2 *
3 * Copyright (C) 2004-2007 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 static 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 static LIST_HEAD(key_types_list);
31 static DECLARE_RWSEM(key_types_sem);
32
33 static void key_cleanup(struct work_struct *work);
34 static DECLARE_WORK(key_cleanup_task, key_cleanup);
35
36 /* we serialise key instantiation and link */
37 DEFINE_MUTEX(key_construction_mutex);
38
39 /* any key who's type gets unegistered will be re-typed to this */
40 static struct key_type key_type_dead = {
41 .name = "dead",
42 };
43
44 #ifdef KEY_DEBUGGING
45 void __key_check(const struct key *key)
46 {
47 printk("__key_check: key %p {%08x} should be {%08x}\n",
48 key, key->magic, KEY_DEBUG_MAGIC);
49 BUG();
50 }
51 #endif
52
53 /*****************************************************************************/
54 /*
55 * get the key quota record for a user, allocating a new record if one doesn't
56 * already exist
57 */
58 struct key_user *key_user_lookup(uid_t uid)
59 {
60 struct key_user *candidate = NULL, *user;
61 struct rb_node *parent = NULL;
62 struct rb_node **p;
63
64 try_again:
65 p = &key_user_tree.rb_node;
66 spin_lock(&key_user_lock);
67
68 /* search the tree for a user record with a matching UID */
69 while (*p) {
70 parent = *p;
71 user = rb_entry(parent, struct key_user, node);
72
73 if (uid < user->uid)
74 p = &(*p)->rb_left;
75 else if (uid > user->uid)
76 p = &(*p)->rb_right;
77 else
78 goto found;
79 }
80
81 /* if we get here, we failed to find a match in the tree */
82 if (!candidate) {
83 /* allocate a candidate user record if we don't already have
84 * one */
85 spin_unlock(&key_user_lock);
86
87 user = NULL;
88 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
89 if (unlikely(!candidate))
90 goto out;
91
92 /* the allocation may have scheduled, so we need to repeat the
93 * search lest someone else added the record whilst we were
94 * asleep */
95 goto try_again;
96 }
97
98 /* if we get here, then the user record still hadn't appeared on the
99 * second pass - so we use the candidate record */
100 atomic_set(&candidate->usage, 1);
101 atomic_set(&candidate->nkeys, 0);
102 atomic_set(&candidate->nikeys, 0);
103 candidate->uid = uid;
104 candidate->qnkeys = 0;
105 candidate->qnbytes = 0;
106 spin_lock_init(&candidate->lock);
107 mutex_init(&candidate->cons_lock);
108
109 rb_link_node(&candidate->node, parent, p);
110 rb_insert_color(&candidate->node, &key_user_tree);
111 spin_unlock(&key_user_lock);
112 user = candidate;
113 goto out;
114
115 /* okay - we found a user record for this UID */
116 found:
117 atomic_inc(&user->usage);
118 spin_unlock(&key_user_lock);
119 kfree(candidate);
120 out:
121 return user;
122
123 } /* end key_user_lookup() */
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
135 kfree(user);
136 }
137
138 } /* end key_user_put() */
139
140 /*****************************************************************************/
141 /*
142 * insert a key with a fixed serial number
143 */
144 static void __init __key_insert_serial(struct key *key)
145 {
146 struct rb_node *parent, **p;
147 struct key *xkey;
148
149 parent = NULL;
150 p = &key_serial_tree.rb_node;
151
152 while (*p) {
153 parent = *p;
154 xkey = rb_entry(parent, struct key, serial_node);
155
156 if (key->serial < xkey->serial)
157 p = &(*p)->rb_left;
158 else if (key->serial > xkey->serial)
159 p = &(*p)->rb_right;
160 else
161 BUG();
162 }
163
164 /* we've found a suitable hole - arrange for this key to occupy it */
165 rb_link_node(&key->serial_node, parent, p);
166 rb_insert_color(&key->serial_node, &key_serial_tree);
167
168 } /* end __key_insert_serial() */
169
170 /*****************************************************************************/
171 /*
172 * assign a key the next unique serial number
173 * - these are assigned randomly to avoid security issues through covert
174 * channel problems
175 */
176 static inline void key_alloc_serial(struct key *key)
177 {
178 struct rb_node *parent, **p;
179 struct key *xkey;
180
181 /* propose a random serial number and look for a hole for it in the
182 * serial number tree */
183 do {
184 get_random_bytes(&key->serial, sizeof(key->serial));
185
186 key->serial >>= 1; /* negative numbers are not permitted */
187 } while (key->serial < 3);
188
189 spin_lock(&key_serial_lock);
190
191 attempt_insertion:
192 parent = NULL;
193 p = &key_serial_tree.rb_node;
194
195 while (*p) {
196 parent = *p;
197 xkey = rb_entry(parent, struct key, serial_node);
198
199 if (key->serial < xkey->serial)
200 p = &(*p)->rb_left;
201 else if (key->serial > xkey->serial)
202 p = &(*p)->rb_right;
203 else
204 goto serial_exists;
205 }
206
207 /* we've found a suitable hole - arrange for this key to occupy it */
208 rb_link_node(&key->serial_node, parent, p);
209 rb_insert_color(&key->serial_node, &key_serial_tree);
210
211 spin_unlock(&key_serial_lock);
212 return;
213
214 /* we found a key with the proposed serial number - walk the tree from
215 * that point looking for the next unused serial number */
216 serial_exists:
217 for (;;) {
218 key->serial++;
219 if (key->serial < 3) {
220 key->serial = 3;
221 goto attempt_insertion;
222 }
223
224 parent = rb_next(parent);
225 if (!parent)
226 goto attempt_insertion;
227
228 xkey = rb_entry(parent, struct key, serial_node);
229 if (key->serial < xkey->serial)
230 goto attempt_insertion;
231 }
232
233 } /* end key_alloc_serial() */
234
235 /*****************************************************************************/
236 /*
237 * allocate a key of the specified type
238 * - update the user's quota to reflect the existence of the key
239 * - called from a key-type operation with key_types_sem read-locked by
240 * key_create_or_update()
241 * - this prevents unregistration of the key type
242 * - upon return the key is as yet uninstantiated; the caller needs to either
243 * instantiate the key or discard it before returning
244 */
245 struct key *key_alloc(struct key_type *type, const char *desc,
246 uid_t uid, gid_t gid, struct task_struct *ctx,
247 key_perm_t perm, unsigned long flags)
248 {
249 struct key_user *user = NULL;
250 struct key *key;
251 size_t desclen, quotalen;
252 int ret;
253
254 key = ERR_PTR(-EINVAL);
255 if (!desc || !*desc)
256 goto error;
257
258 desclen = strlen(desc) + 1;
259 quotalen = desclen + type->def_datalen;
260
261 /* get hold of the key tracking for this user */
262 user = key_user_lookup(uid);
263 if (!user)
264 goto no_memory_1;
265
266 /* check that the user's quota permits allocation of another key and
267 * its description */
268 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
269 spin_lock(&user->lock);
270 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
271 if (user->qnkeys + 1 >= KEYQUOTA_MAX_KEYS ||
272 user->qnbytes + quotalen >= KEYQUOTA_MAX_BYTES
273 )
274 goto no_quota;
275 }
276
277 user->qnkeys++;
278 user->qnbytes += quotalen;
279 spin_unlock(&user->lock);
280 }
281
282 /* allocate and initialise the key and its description */
283 key = kmem_cache_alloc(key_jar, GFP_KERNEL);
284 if (!key)
285 goto no_memory_2;
286
287 if (desc) {
288 key->description = kmemdup(desc, desclen, GFP_KERNEL);
289 if (!key->description)
290 goto no_memory_3;
291 }
292
293 atomic_set(&key->usage, 1);
294 init_rwsem(&key->sem);
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, ctx, 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 } /* end key_alloc() */
362
363 EXPORT_SYMBOL(key_alloc);
364
365 /*****************************************************************************/
366 /*
367 * reserve an amount of quota for the key's payload
368 */
369 int key_payload_reserve(struct key *key, size_t datalen)
370 {
371 int delta = (int) datalen - key->datalen;
372 int ret = 0;
373
374 key_check(key);
375
376 /* contemplate the quota adjustment */
377 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
378 spin_lock(&key->user->lock);
379
380 if (delta > 0 &&
381 key->user->qnbytes + delta > KEYQUOTA_MAX_BYTES
382 ) {
383 ret = -EDQUOT;
384 }
385 else {
386 key->user->qnbytes += delta;
387 key->quotalen += delta;
388 }
389 spin_unlock(&key->user->lock);
390 }
391
392 /* change the recorded data length if that didn't generate an error */
393 if (ret == 0)
394 key->datalen = datalen;
395
396 return ret;
397
398 } /* end key_payload_reserve() */
399
400 EXPORT_SYMBOL(key_payload_reserve);
401
402 /*****************************************************************************/
403 /*
404 * instantiate a key and link it into the target keyring atomically
405 * - called with the target keyring's semaphore writelocked
406 */
407 static int __key_instantiate_and_link(struct key *key,
408 const void *data,
409 size_t datalen,
410 struct key *keyring,
411 struct key *instkey)
412 {
413 int ret, awaken;
414
415 key_check(key);
416 key_check(keyring);
417
418 awaken = 0;
419 ret = -EBUSY;
420
421 mutex_lock(&key_construction_mutex);
422
423 /* can't instantiate twice */
424 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
425 /* instantiate the key */
426 ret = key->type->instantiate(key, data, datalen);
427
428 if (ret == 0) {
429 /* mark the key as being instantiated */
430 atomic_inc(&key->user->nikeys);
431 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
432
433 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
434 awaken = 1;
435
436 /* and link it into the destination keyring */
437 if (keyring)
438 ret = __key_link(keyring, key);
439
440 /* disable the authorisation key */
441 if (instkey)
442 key_revoke(instkey);
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 } /* end __key_instantiate_and_link() */
455
456 /*****************************************************************************/
457 /*
458 * instantiate a key and link it into the target keyring atomically
459 */
460 int key_instantiate_and_link(struct key *key,
461 const void *data,
462 size_t datalen,
463 struct key *keyring,
464 struct key *instkey)
465 {
466 int ret;
467
468 if (keyring)
469 down_write(&keyring->sem);
470
471 ret = __key_instantiate_and_link(key, data, datalen, keyring, instkey);
472
473 if (keyring)
474 up_write(&keyring->sem);
475
476 return ret;
477
478 } /* end key_instantiate_and_link() */
479
480 EXPORT_SYMBOL(key_instantiate_and_link);
481
482 /*****************************************************************************/
483 /*
484 * negatively instantiate a key and link it into the target keyring atomically
485 */
486 int key_negate_and_link(struct key *key,
487 unsigned timeout,
488 struct key *keyring,
489 struct key *instkey)
490 {
491 struct timespec now;
492 int ret, awaken;
493
494 key_check(key);
495 key_check(keyring);
496
497 awaken = 0;
498 ret = -EBUSY;
499
500 if (keyring)
501 down_write(&keyring->sem);
502
503 mutex_lock(&key_construction_mutex);
504
505 /* can't instantiate twice */
506 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
507 /* mark the key as being negatively instantiated */
508 atomic_inc(&key->user->nikeys);
509 set_bit(KEY_FLAG_NEGATIVE, &key->flags);
510 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
511 now = current_kernel_time();
512 key->expiry = now.tv_sec + timeout;
513
514 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
515 awaken = 1;
516
517 ret = 0;
518
519 /* and link it into the destination keyring */
520 if (keyring)
521 ret = __key_link(keyring, key);
522
523 /* disable the authorisation key */
524 if (instkey)
525 key_revoke(instkey);
526 }
527
528 mutex_unlock(&key_construction_mutex);
529
530 if (keyring)
531 up_write(&keyring->sem);
532
533 /* wake up anyone waiting for a key to be constructed */
534 if (awaken)
535 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
536
537 return ret;
538
539 } /* end key_negate_and_link() */
540
541 EXPORT_SYMBOL(key_negate_and_link);
542
543 /*****************************************************************************/
544 /*
545 * do cleaning up in process context so that we don't have to disable
546 * interrupts all over the place
547 */
548 static void key_cleanup(struct work_struct *work)
549 {
550 struct rb_node *_n;
551 struct key *key;
552
553 go_again:
554 /* look for a dead key in the tree */
555 spin_lock(&key_serial_lock);
556
557 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
558 key = rb_entry(_n, struct key, serial_node);
559
560 if (atomic_read(&key->usage) == 0)
561 goto found_dead_key;
562 }
563
564 spin_unlock(&key_serial_lock);
565 return;
566
567 found_dead_key:
568 /* we found a dead key - once we've removed it from the tree, we can
569 * drop the lock */
570 rb_erase(&key->serial_node, &key_serial_tree);
571 spin_unlock(&key_serial_lock);
572
573 key_check(key);
574
575 security_key_free(key);
576
577 /* deal with the user's key tracking and quota */
578 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
579 spin_lock(&key->user->lock);
580 key->user->qnkeys--;
581 key->user->qnbytes -= key->quotalen;
582 spin_unlock(&key->user->lock);
583 }
584
585 atomic_dec(&key->user->nkeys);
586 if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
587 atomic_dec(&key->user->nikeys);
588
589 key_user_put(key->user);
590
591 /* now throw away the key memory */
592 if (key->type->destroy)
593 key->type->destroy(key);
594
595 kfree(key->description);
596
597 #ifdef KEY_DEBUGGING
598 key->magic = KEY_DEBUG_MAGIC_X;
599 #endif
600 kmem_cache_free(key_jar, key);
601
602 /* there may, of course, be more than one key to destroy */
603 goto go_again;
604
605 } /* end key_cleanup() */
606
607 /*****************************************************************************/
608 /*
609 * dispose of a reference to a key
610 * - when all the references are gone, we schedule the cleanup task to come and
611 * pull it out of the tree in definite process context
612 */
613 void key_put(struct key *key)
614 {
615 if (key) {
616 key_check(key);
617
618 if (atomic_dec_and_test(&key->usage))
619 schedule_work(&key_cleanup_task);
620 }
621
622 } /* end key_put() */
623
624 EXPORT_SYMBOL(key_put);
625
626 /*****************************************************************************/
627 /*
628 * find a key by its serial number
629 */
630 struct key *key_lookup(key_serial_t id)
631 {
632 struct rb_node *n;
633 struct key *key;
634
635 spin_lock(&key_serial_lock);
636
637 /* search the tree for the specified key */
638 n = key_serial_tree.rb_node;
639 while (n) {
640 key = rb_entry(n, struct key, serial_node);
641
642 if (id < key->serial)
643 n = n->rb_left;
644 else if (id > key->serial)
645 n = n->rb_right;
646 else
647 goto found;
648 }
649
650 not_found:
651 key = ERR_PTR(-ENOKEY);
652 goto error;
653
654 found:
655 /* pretend it doesn't exist if it's dead */
656 if (atomic_read(&key->usage) == 0 ||
657 test_bit(KEY_FLAG_DEAD, &key->flags) ||
658 key->type == &key_type_dead)
659 goto not_found;
660
661 /* this races with key_put(), but that doesn't matter since key_put()
662 * doesn't actually change the key
663 */
664 atomic_inc(&key->usage);
665
666 error:
667 spin_unlock(&key_serial_lock);
668 return key;
669
670 } /* end key_lookup() */
671
672 /*****************************************************************************/
673 /*
674 * find and lock the specified key type against removal
675 * - we return with the sem readlocked
676 */
677 struct key_type *key_type_lookup(const char *type)
678 {
679 struct key_type *ktype;
680
681 down_read(&key_types_sem);
682
683 /* look up the key type to see if it's one of the registered kernel
684 * types */
685 list_for_each_entry(ktype, &key_types_list, link) {
686 if (strcmp(ktype->name, type) == 0)
687 goto found_kernel_type;
688 }
689
690 up_read(&key_types_sem);
691 ktype = ERR_PTR(-ENOKEY);
692
693 found_kernel_type:
694 return ktype;
695
696 } /* end key_type_lookup() */
697
698 /*****************************************************************************/
699 /*
700 * unlock a key type
701 */
702 void key_type_put(struct key_type *ktype)
703 {
704 up_read(&key_types_sem);
705
706 } /* end key_type_put() */
707
708 /*****************************************************************************/
709 /*
710 * attempt to update an existing key
711 * - the key has an incremented refcount
712 * - we need to put the key if we get an error
713 */
714 static inline key_ref_t __key_update(key_ref_t key_ref,
715 const void *payload, size_t plen)
716 {
717 struct key *key = key_ref_to_ptr(key_ref);
718 int ret;
719
720 /* need write permission on the key to update it */
721 ret = key_permission(key_ref, KEY_WRITE);
722 if (ret < 0)
723 goto error;
724
725 ret = -EEXIST;
726 if (!key->type->update)
727 goto error;
728
729 down_write(&key->sem);
730
731 ret = key->type->update(key, payload, plen);
732 if (ret == 0)
733 /* updating a negative key instantiates it */
734 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
735
736 up_write(&key->sem);
737
738 if (ret < 0)
739 goto error;
740 out:
741 return key_ref;
742
743 error:
744 key_put(key);
745 key_ref = ERR_PTR(ret);
746 goto out;
747
748 } /* end __key_update() */
749
750 /*****************************************************************************/
751 /*
752 * search the specified keyring for a key of the same description; if one is
753 * found, update it, otherwise add a new one
754 */
755 key_ref_t key_create_or_update(key_ref_t keyring_ref,
756 const char *type,
757 const char *description,
758 const void *payload,
759 size_t plen,
760 unsigned long flags)
761 {
762 struct key_type *ktype;
763 struct key *keyring, *key = NULL;
764 key_perm_t perm;
765 key_ref_t key_ref;
766 int ret;
767
768 /* look up the key type to see if it's one of the registered kernel
769 * types */
770 ktype = key_type_lookup(type);
771 if (IS_ERR(ktype)) {
772 key_ref = ERR_PTR(-ENODEV);
773 goto error;
774 }
775
776 key_ref = ERR_PTR(-EINVAL);
777 if (!ktype->match || !ktype->instantiate)
778 goto error_2;
779
780 keyring = key_ref_to_ptr(keyring_ref);
781
782 key_check(keyring);
783
784 key_ref = ERR_PTR(-ENOTDIR);
785 if (keyring->type != &key_type_keyring)
786 goto error_2;
787
788 down_write(&keyring->sem);
789
790 /* if we're going to allocate a new key, we're going to have
791 * to modify the keyring */
792 ret = key_permission(keyring_ref, KEY_WRITE);
793 if (ret < 0) {
794 key_ref = ERR_PTR(ret);
795 goto error_3;
796 }
797
798 /* if it's possible to update this type of key, search for an existing
799 * key of the same type and description in the destination keyring and
800 * update that instead if possible
801 */
802 if (ktype->update) {
803 key_ref = __keyring_search_one(keyring_ref, ktype, description,
804 0);
805 if (!IS_ERR(key_ref))
806 goto found_matching_key;
807 }
808
809 /* decide on the permissions we want */
810 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
811 perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR;
812
813 if (ktype->read)
814 perm |= KEY_POS_READ | KEY_USR_READ;
815
816 if (ktype == &key_type_keyring || ktype->update)
817 perm |= KEY_USR_WRITE;
818
819 /* allocate a new key */
820 key = key_alloc(ktype, description, current->fsuid, current->fsgid,
821 current, perm, flags);
822 if (IS_ERR(key)) {
823 key_ref = ERR_CAST(key);
824 goto error_3;
825 }
826
827 /* instantiate it and link it into the target keyring */
828 ret = __key_instantiate_and_link(key, payload, plen, keyring, NULL);
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 up_write(&keyring->sem);
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 up_write(&keyring->sem);
849 key_type_put(ktype);
850
851 key_ref = __key_update(key_ref, payload, plen);
852 goto error;
853
854 } /* end key_create_or_update() */
855
856 EXPORT_SYMBOL(key_create_or_update);
857
858 /*****************************************************************************/
859 /*
860 * update a key
861 */
862 int key_update(key_ref_t key_ref, const void *payload, size_t plen)
863 {
864 struct key *key = key_ref_to_ptr(key_ref);
865 int ret;
866
867 key_check(key);
868
869 /* the key must be writable */
870 ret = key_permission(key_ref, KEY_WRITE);
871 if (ret < 0)
872 goto error;
873
874 /* attempt to update it if supported */
875 ret = -EOPNOTSUPP;
876 if (key->type->update) {
877 down_write(&key->sem);
878
879 ret = key->type->update(key, payload, plen);
880 if (ret == 0)
881 /* updating a negative key instantiates it */
882 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
883
884 up_write(&key->sem);
885 }
886
887 error:
888 return ret;
889
890 } /* end key_update() */
891
892 EXPORT_SYMBOL(key_update);
893
894 /*****************************************************************************/
895 /*
896 * revoke a key
897 */
898 void key_revoke(struct key *key)
899 {
900 key_check(key);
901
902 /* make sure no one's trying to change or use the key when we mark it
903 * - we tell lockdep that we might nest because we might be revoking an
904 * authorisation key whilst holding the sem on a key we've just
905 * instantiated
906 */
907 down_write_nested(&key->sem, 1);
908 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
909 key->type->revoke)
910 key->type->revoke(key);
911
912 up_write(&key->sem);
913
914 } /* end key_revoke() */
915
916 EXPORT_SYMBOL(key_revoke);
917
918 /*****************************************************************************/
919 /*
920 * register a type of key
921 */
922 int register_key_type(struct key_type *ktype)
923 {
924 struct key_type *p;
925 int ret;
926
927 ret = -EEXIST;
928 down_write(&key_types_sem);
929
930 /* disallow key types with the same name */
931 list_for_each_entry(p, &key_types_list, link) {
932 if (strcmp(p->name, ktype->name) == 0)
933 goto out;
934 }
935
936 /* store the type */
937 list_add(&ktype->link, &key_types_list);
938 ret = 0;
939
940 out:
941 up_write(&key_types_sem);
942 return ret;
943
944 } /* end register_key_type() */
945
946 EXPORT_SYMBOL(register_key_type);
947
948 /*****************************************************************************/
949 /*
950 * unregister a type of key
951 */
952 void unregister_key_type(struct key_type *ktype)
953 {
954 struct rb_node *_n;
955 struct key *key;
956
957 down_write(&key_types_sem);
958
959 /* withdraw the key type */
960 list_del_init(&ktype->link);
961
962 /* mark all the keys of this type dead */
963 spin_lock(&key_serial_lock);
964
965 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
966 key = rb_entry(_n, struct key, serial_node);
967
968 if (key->type == ktype)
969 key->type = &key_type_dead;
970 }
971
972 spin_unlock(&key_serial_lock);
973
974 /* make sure everyone revalidates their keys */
975 synchronize_rcu();
976
977 /* we should now be able to destroy the payloads of all the keys of
978 * this type with impunity */
979 spin_lock(&key_serial_lock);
980
981 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
982 key = rb_entry(_n, struct key, serial_node);
983
984 if (key->type == ktype) {
985 if (ktype->destroy)
986 ktype->destroy(key);
987 memset(&key->payload, KEY_DESTROY, sizeof(key->payload));
988 }
989 }
990
991 spin_unlock(&key_serial_lock);
992 up_write(&key_types_sem);
993
994 } /* end unregister_key_type() */
995
996 EXPORT_SYMBOL(unregister_key_type);
997
998 /*****************************************************************************/
999 /*
1000 * initialise the key management stuff
1001 */
1002 void __init key_init(void)
1003 {
1004 /* allocate a slab in which we can store keys */
1005 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1006 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1007
1008 /* add the special key types */
1009 list_add_tail(&key_type_keyring.link, &key_types_list);
1010 list_add_tail(&key_type_dead.link, &key_types_list);
1011 list_add_tail(&key_type_user.link, &key_types_list);
1012
1013 /* record the root user tracking */
1014 rb_link_node(&root_key_user.node,
1015 NULL,
1016 &key_user_tree.rb_node);
1017
1018 rb_insert_color(&root_key_user.node,
1019 &key_user_tree);
1020
1021 /* record root's user standard keyrings */
1022 key_check(&root_user_keyring);
1023 key_check(&root_session_keyring);
1024
1025 __key_insert_serial(&root_user_keyring);
1026 __key_insert_serial(&root_session_keyring);
1027
1028 keyring_publish_name(&root_user_keyring);
1029 keyring_publish_name(&root_session_keyring);
1030
1031 /* link the two root keyrings together */
1032 key_link(&root_session_keyring, &root_user_keyring);
1033
1034 } /* end key_init() */
1035
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