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 static 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 static void key_cleanup(struct work_struct *work);
40 static DECLARE_WORK(key_cleanup_task, key_cleanup);
41
42 /* we serialise key instantiation and link */
43 DEFINE_MUTEX(key_construction_mutex);
44
45 /* any key who's type gets unegistered will be re-typed to this */
46 static struct key_type key_type_dead = {
47 .name = "dead",
48 };
49
50 #ifdef KEY_DEBUGGING
51 void __key_check(const struct key *key)
52 {
53 printk("__key_check: key %p {%08x} should be {%08x}\n",
54 key, key->magic, KEY_DEBUG_MAGIC);
55 BUG();
56 }
57 #endif
58
59 /*****************************************************************************/
60 /*
61 * get the key quota record for a user, allocating a new record if one doesn't
62 * already exist
63 */
64 struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns)
65 {
66 struct key_user *candidate = NULL, *user;
67 struct rb_node *parent = NULL;
68 struct rb_node **p;
69
70 try_again:
71 p = &key_user_tree.rb_node;
72 spin_lock(&key_user_lock);
73
74 /* search the tree for a user record with a matching UID */
75 while (*p) {
76 parent = *p;
77 user = rb_entry(parent, struct key_user, node);
78
79 if (uid < user->uid)
80 p = &(*p)->rb_left;
81 else if (uid > user->uid)
82 p = &(*p)->rb_right;
83 else if (user_ns < user->user_ns)
84 p = &(*p)->rb_left;
85 else if (user_ns > user->user_ns)
86 p = &(*p)->rb_right;
87 else
88 goto found;
89 }
90
91 /* if we get here, we failed to find a match in the tree */
92 if (!candidate) {
93 /* allocate a candidate user record if we don't already have
94 * one */
95 spin_unlock(&key_user_lock);
96
97 user = NULL;
98 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
99 if (unlikely(!candidate))
100 goto out;
101
102 /* the allocation may have scheduled, so we need to repeat the
103 * search lest someone else added the record whilst we were
104 * asleep */
105 goto try_again;
106 }
107
108 /* if we get here, then the user record still hadn't appeared on the
109 * second pass - so we use the candidate record */
110 atomic_set(&candidate->usage, 1);
111 atomic_set(&candidate->nkeys, 0);
112 atomic_set(&candidate->nikeys, 0);
113 candidate->uid = uid;
114 candidate->user_ns = get_user_ns(user_ns);
115 candidate->qnkeys = 0;
116 candidate->qnbytes = 0;
117 spin_lock_init(&candidate->lock);
118 mutex_init(&candidate->cons_lock);
119
120 rb_link_node(&candidate->node, parent, p);
121 rb_insert_color(&candidate->node, &key_user_tree);
122 spin_unlock(&key_user_lock);
123 user = candidate;
124 goto out;
125
126 /* okay - we found a user record for this UID */
127 found:
128 atomic_inc(&user->usage);
129 spin_unlock(&key_user_lock);
130 kfree(candidate);
131 out:
132 return user;
133
134 } /* end key_user_lookup() */
135
136 /*****************************************************************************/
137 /*
138 * dispose of a user structure
139 */
140 void key_user_put(struct key_user *user)
141 {
142 if (atomic_dec_and_lock(&user->usage, &key_user_lock)) {
143 rb_erase(&user->node, &key_user_tree);
144 spin_unlock(&key_user_lock);
145 put_user_ns(user->user_ns);
146
147 kfree(user);
148 }
149
150 } /* end key_user_put() */
151
152 /*****************************************************************************/
153 /*
154 * assign a key the next unique serial number
155 * - these are assigned randomly to avoid security issues through covert
156 * channel problems
157 */
158 static inline void key_alloc_serial(struct key *key)
159 {
160 struct rb_node *parent, **p;
161 struct key *xkey;
162
163 /* propose a random serial number and look for a hole for it in the
164 * serial number tree */
165 do {
166 get_random_bytes(&key->serial, sizeof(key->serial));
167
168 key->serial >>= 1; /* negative numbers are not permitted */
169 } while (key->serial < 3);
170
171 spin_lock(&key_serial_lock);
172
173 attempt_insertion:
174 parent = NULL;
175 p = &key_serial_tree.rb_node;
176
177 while (*p) {
178 parent = *p;
179 xkey = rb_entry(parent, struct key, serial_node);
180
181 if (key->serial < xkey->serial)
182 p = &(*p)->rb_left;
183 else if (key->serial > xkey->serial)
184 p = &(*p)->rb_right;
185 else
186 goto serial_exists;
187 }
188
189 /* we've found a suitable hole - arrange for this key to occupy it */
190 rb_link_node(&key->serial_node, parent, p);
191 rb_insert_color(&key->serial_node, &key_serial_tree);
192
193 spin_unlock(&key_serial_lock);
194 return;
195
196 /* we found a key with the proposed serial number - walk the tree from
197 * that point looking for the next unused serial number */
198 serial_exists:
199 for (;;) {
200 key->serial++;
201 if (key->serial < 3) {
202 key->serial = 3;
203 goto attempt_insertion;
204 }
205
206 parent = rb_next(parent);
207 if (!parent)
208 goto attempt_insertion;
209
210 xkey = rb_entry(parent, struct key, serial_node);
211 if (key->serial < xkey->serial)
212 goto attempt_insertion;
213 }
214
215 } /* end key_alloc_serial() */
216
217 /*****************************************************************************/
218 /*
219 * allocate a key of the specified type
220 * - update the user's quota to reflect the existence of the key
221 * - called from a key-type operation with key_types_sem read-locked by
222 * key_create_or_update()
223 * - this prevents unregistration of the key type
224 * - upon return the key is as yet uninstantiated; the caller needs to either
225 * instantiate the key or discard it before returning
226 */
227 struct key *key_alloc(struct key_type *type, const char *desc,
228 uid_t uid, gid_t gid, const struct cred *cred,
229 key_perm_t perm, unsigned long flags)
230 {
231 struct key_user *user = NULL;
232 struct key *key;
233 size_t desclen, quotalen;
234 int ret;
235
236 key = ERR_PTR(-EINVAL);
237 if (!desc || !*desc)
238 goto error;
239
240 desclen = strlen(desc) + 1;
241 quotalen = desclen + type->def_datalen;
242
243 /* get hold of the key tracking for this user */
244 user = key_user_lookup(uid, cred->user->user_ns);
245 if (!user)
246 goto no_memory_1;
247
248 /* check that the user's quota permits allocation of another key and
249 * its description */
250 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
251 unsigned maxkeys = (uid == 0) ?
252 key_quota_root_maxkeys : key_quota_maxkeys;
253 unsigned maxbytes = (uid == 0) ?
254 key_quota_root_maxbytes : key_quota_maxbytes;
255
256 spin_lock(&user->lock);
257 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
258 if (user->qnkeys + 1 >= maxkeys ||
259 user->qnbytes + quotalen >= maxbytes ||
260 user->qnbytes + quotalen < user->qnbytes)
261 goto no_quota;
262 }
263
264 user->qnkeys++;
265 user->qnbytes += quotalen;
266 spin_unlock(&user->lock);
267 }
268
269 /* allocate and initialise the key and its description */
270 key = kmem_cache_alloc(key_jar, GFP_KERNEL);
271 if (!key)
272 goto no_memory_2;
273
274 if (desc) {
275 key->description = kmemdup(desc, desclen, GFP_KERNEL);
276 if (!key->description)
277 goto no_memory_3;
278 }
279
280 atomic_set(&key->usage, 1);
281 init_rwsem(&key->sem);
282 key->type = type;
283 key->user = user;
284 key->quotalen = quotalen;
285 key->datalen = type->def_datalen;
286 key->uid = uid;
287 key->gid = gid;
288 key->perm = perm;
289 key->flags = 0;
290 key->expiry = 0;
291 key->payload.data = NULL;
292 key->security = NULL;
293
294 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
295 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
296
297 memset(&key->type_data, 0, sizeof(key->type_data));
298
299 #ifdef KEY_DEBUGGING
300 key->magic = KEY_DEBUG_MAGIC;
301 #endif
302
303 /* let the security module know about the key */
304 ret = security_key_alloc(key, cred, flags);
305 if (ret < 0)
306 goto security_error;
307
308 /* publish the key by giving it a serial number */
309 atomic_inc(&user->nkeys);
310 key_alloc_serial(key);
311
312 error:
313 return key;
314
315 security_error:
316 kfree(key->description);
317 kmem_cache_free(key_jar, key);
318 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
319 spin_lock(&user->lock);
320 user->qnkeys--;
321 user->qnbytes -= quotalen;
322 spin_unlock(&user->lock);
323 }
324 key_user_put(user);
325 key = ERR_PTR(ret);
326 goto error;
327
328 no_memory_3:
329 kmem_cache_free(key_jar, key);
330 no_memory_2:
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 no_memory_1:
339 key = ERR_PTR(-ENOMEM);
340 goto error;
341
342 no_quota:
343 spin_unlock(&user->lock);
344 key_user_put(user);
345 key = ERR_PTR(-EDQUOT);
346 goto error;
347
348 } /* end key_alloc() */
349
350 EXPORT_SYMBOL(key_alloc);
351
352 /*****************************************************************************/
353 /*
354 * reserve an amount of quota for the key's payload
355 */
356 int key_payload_reserve(struct key *key, size_t datalen)
357 {
358 int delta = (int) datalen - key->datalen;
359 int ret = 0;
360
361 key_check(key);
362
363 /* contemplate the quota adjustment */
364 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
365 unsigned maxbytes = (key->user->uid == 0) ?
366 key_quota_root_maxbytes : key_quota_maxbytes;
367
368 spin_lock(&key->user->lock);
369
370 if (delta > 0 &&
371 (key->user->qnbytes + delta >= maxbytes ||
372 key->user->qnbytes + delta < key->user->qnbytes)) {
373 ret = -EDQUOT;
374 }
375 else {
376 key->user->qnbytes += delta;
377 key->quotalen += delta;
378 }
379 spin_unlock(&key->user->lock);
380 }
381
382 /* change the recorded data length if that didn't generate an error */
383 if (ret == 0)
384 key->datalen = datalen;
385
386 return ret;
387
388 } /* end key_payload_reserve() */
389
390 EXPORT_SYMBOL(key_payload_reserve);
391
392 /*****************************************************************************/
393 /*
394 * instantiate a key and link it into the target keyring atomically
395 * - called with the target keyring's semaphore writelocked
396 */
397 static int __key_instantiate_and_link(struct key *key,
398 const void *data,
399 size_t datalen,
400 struct key *keyring,
401 struct key *authkey)
402 {
403 int ret, awaken;
404
405 key_check(key);
406 key_check(keyring);
407
408 awaken = 0;
409 ret = -EBUSY;
410
411 mutex_lock(&key_construction_mutex);
412
413 /* can't instantiate twice */
414 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
415 /* instantiate the key */
416 ret = key->type->instantiate(key, data, datalen);
417
418 if (ret == 0) {
419 /* mark the key as being instantiated */
420 atomic_inc(&key->user->nikeys);
421 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
422
423 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
424 awaken = 1;
425
426 /* and link it into the destination keyring */
427 if (keyring)
428 ret = __key_link(keyring, key);
429
430 /* disable the authorisation key */
431 if (authkey)
432 key_revoke(authkey);
433 }
434 }
435
436 mutex_unlock(&key_construction_mutex);
437
438 /* wake up anyone waiting for a key to be constructed */
439 if (awaken)
440 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
441
442 return ret;
443
444 } /* end __key_instantiate_and_link() */
445
446 /*****************************************************************************/
447 /*
448 * instantiate a key and link it into the target keyring atomically
449 */
450 int key_instantiate_and_link(struct key *key,
451 const void *data,
452 size_t datalen,
453 struct key *keyring,
454 struct key *authkey)
455 {
456 int ret;
457
458 if (keyring)
459 down_write(&keyring->sem);
460
461 ret = __key_instantiate_and_link(key, data, datalen, keyring, authkey);
462
463 if (keyring)
464 up_write(&keyring->sem);
465
466 return ret;
467
468 } /* end key_instantiate_and_link() */
469
470 EXPORT_SYMBOL(key_instantiate_and_link);
471
472 /*****************************************************************************/
473 /*
474 * negatively instantiate a key and link it into the target keyring atomically
475 */
476 int key_negate_and_link(struct key *key,
477 unsigned timeout,
478 struct key *keyring,
479 struct key *authkey)
480 {
481 struct timespec now;
482 int ret, awaken;
483
484 key_check(key);
485 key_check(keyring);
486
487 awaken = 0;
488 ret = -EBUSY;
489
490 if (keyring)
491 down_write(&keyring->sem);
492
493 mutex_lock(&key_construction_mutex);
494
495 /* can't instantiate twice */
496 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
497 /* mark the key as being negatively instantiated */
498 atomic_inc(&key->user->nikeys);
499 set_bit(KEY_FLAG_NEGATIVE, &key->flags);
500 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
501 now = current_kernel_time();
502 key->expiry = now.tv_sec + timeout;
503
504 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
505 awaken = 1;
506
507 ret = 0;
508
509 /* and link it into the destination keyring */
510 if (keyring)
511 ret = __key_link(keyring, key);
512
513 /* disable the authorisation key */
514 if (authkey)
515 key_revoke(authkey);
516 }
517
518 mutex_unlock(&key_construction_mutex);
519
520 if (keyring)
521 up_write(&keyring->sem);
522
523 /* wake up anyone waiting for a key to be constructed */
524 if (awaken)
525 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
526
527 return ret;
528
529 } /* end key_negate_and_link() */
530
531 EXPORT_SYMBOL(key_negate_and_link);
532
533 /*****************************************************************************/
534 /*
535 * do cleaning up in process context so that we don't have to disable
536 * interrupts all over the place
537 */
538 static void key_cleanup(struct work_struct *work)
539 {
540 struct rb_node *_n;
541 struct key *key;
542
543 go_again:
544 /* look for a dead key in the tree */
545 spin_lock(&key_serial_lock);
546
547 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
548 key = rb_entry(_n, struct key, serial_node);
549
550 if (atomic_read(&key->usage) == 0)
551 goto found_dead_key;
552 }
553
554 spin_unlock(&key_serial_lock);
555 return;
556
557 found_dead_key:
558 /* we found a dead key - once we've removed it from the tree, we can
559 * drop the lock */
560 rb_erase(&key->serial_node, &key_serial_tree);
561 spin_unlock(&key_serial_lock);
562
563 key_check(key);
564
565 security_key_free(key);
566
567 /* deal with the user's key tracking and quota */
568 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
569 spin_lock(&key->user->lock);
570 key->user->qnkeys--;
571 key->user->qnbytes -= key->quotalen;
572 spin_unlock(&key->user->lock);
573 }
574
575 atomic_dec(&key->user->nkeys);
576 if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
577 atomic_dec(&key->user->nikeys);
578
579 key_user_put(key->user);
580
581 /* now throw away the key memory */
582 if (key->type->destroy)
583 key->type->destroy(key);
584
585 kfree(key->description);
586
587 #ifdef KEY_DEBUGGING
588 key->magic = KEY_DEBUG_MAGIC_X;
589 #endif
590 kmem_cache_free(key_jar, key);
591
592 /* there may, of course, be more than one key to destroy */
593 goto go_again;
594
595 } /* end key_cleanup() */
596
597 /*****************************************************************************/
598 /*
599 * dispose of a reference to a key
600 * - when all the references are gone, we schedule the cleanup task to come and
601 * pull it out of the tree in definite process context
602 */
603 void key_put(struct key *key)
604 {
605 if (key) {
606 key_check(key);
607
608 if (atomic_dec_and_test(&key->usage))
609 schedule_work(&key_cleanup_task);
610 }
611
612 } /* end key_put() */
613
614 EXPORT_SYMBOL(key_put);
615
616 /*****************************************************************************/
617 /*
618 * find a key by its serial number
619 */
620 struct key *key_lookup(key_serial_t id)
621 {
622 struct rb_node *n;
623 struct key *key;
624
625 spin_lock(&key_serial_lock);
626
627 /* search the tree for the specified key */
628 n = key_serial_tree.rb_node;
629 while (n) {
630 key = rb_entry(n, struct key, serial_node);
631
632 if (id < key->serial)
633 n = n->rb_left;
634 else if (id > key->serial)
635 n = n->rb_right;
636 else
637 goto found;
638 }
639
640 not_found:
641 key = ERR_PTR(-ENOKEY);
642 goto error;
643
644 found:
645 /* pretend it doesn't exist if it's dead */
646 if (atomic_read(&key->usage) == 0 ||
647 test_bit(KEY_FLAG_DEAD, &key->flags) ||
648 key->type == &key_type_dead)
649 goto not_found;
650
651 /* this races with key_put(), but that doesn't matter since key_put()
652 * doesn't actually change the key
653 */
654 atomic_inc(&key->usage);
655
656 error:
657 spin_unlock(&key_serial_lock);
658 return key;
659
660 } /* end key_lookup() */
661
662 /*****************************************************************************/
663 /*
664 * find and lock the specified key type against removal
665 * - we return with the sem readlocked
666 */
667 struct key_type *key_type_lookup(const char *type)
668 {
669 struct key_type *ktype;
670
671 down_read(&key_types_sem);
672
673 /* look up the key type to see if it's one of the registered kernel
674 * types */
675 list_for_each_entry(ktype, &key_types_list, link) {
676 if (strcmp(ktype->name, type) == 0)
677 goto found_kernel_type;
678 }
679
680 up_read(&key_types_sem);
681 ktype = ERR_PTR(-ENOKEY);
682
683 found_kernel_type:
684 return ktype;
685
686 } /* end key_type_lookup() */
687
688 /*****************************************************************************/
689 /*
690 * unlock a key type
691 */
692 void key_type_put(struct key_type *ktype)
693 {
694 up_read(&key_types_sem);
695
696 } /* end key_type_put() */
697
698 /*****************************************************************************/
699 /*
700 * attempt to update an existing key
701 * - the key has an incremented refcount
702 * - we need to put the key if we get an error
703 */
704 static inline key_ref_t __key_update(key_ref_t key_ref,
705 const void *payload, size_t plen)
706 {
707 struct key *key = key_ref_to_ptr(key_ref);
708 int ret;
709
710 /* need write permission on the key to update it */
711 ret = key_permission(key_ref, KEY_WRITE);
712 if (ret < 0)
713 goto error;
714
715 ret = -EEXIST;
716 if (!key->type->update)
717 goto error;
718
719 down_write(&key->sem);
720
721 ret = key->type->update(key, payload, plen);
722 if (ret == 0)
723 /* updating a negative key instantiates it */
724 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
725
726 up_write(&key->sem);
727
728 if (ret < 0)
729 goto error;
730 out:
731 return key_ref;
732
733 error:
734 key_put(key);
735 key_ref = ERR_PTR(ret);
736 goto out;
737
738 } /* end __key_update() */
739
740 /*****************************************************************************/
741 /*
742 * search the specified keyring for a key of the same description; if one is
743 * found, update it, otherwise add a new one
744 */
745 key_ref_t key_create_or_update(key_ref_t keyring_ref,
746 const char *type,
747 const char *description,
748 const void *payload,
749 size_t plen,
750 key_perm_t perm,
751 unsigned long flags)
752 {
753 const struct cred *cred = current_cred();
754 struct key_type *ktype;
755 struct key *keyring, *key = NULL;
756 key_ref_t key_ref;
757 int ret;
758
759 /* look up the key type to see if it's one of the registered kernel
760 * types */
761 ktype = key_type_lookup(type);
762 if (IS_ERR(ktype)) {
763 key_ref = ERR_PTR(-ENODEV);
764 goto error;
765 }
766
767 key_ref = ERR_PTR(-EINVAL);
768 if (!ktype->match || !ktype->instantiate)
769 goto error_2;
770
771 keyring = key_ref_to_ptr(keyring_ref);
772
773 key_check(keyring);
774
775 key_ref = ERR_PTR(-ENOTDIR);
776 if (keyring->type != &key_type_keyring)
777 goto error_2;
778
779 down_write(&keyring->sem);
780
781 /* if we're going to allocate a new key, we're going to have
782 * to modify the keyring */
783 ret = key_permission(keyring_ref, KEY_WRITE);
784 if (ret < 0) {
785 key_ref = ERR_PTR(ret);
786 goto error_3;
787 }
788
789 /* if it's possible to update this type of key, search for an existing
790 * key of the same type and description in the destination keyring and
791 * update that instead if possible
792 */
793 if (ktype->update) {
794 key_ref = __keyring_search_one(keyring_ref, ktype, description,
795 0);
796 if (!IS_ERR(key_ref))
797 goto found_matching_key;
798 }
799
800 /* if the client doesn't provide, decide on the permissions we want */
801 if (perm == KEY_PERM_UNDEF) {
802 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
803 perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR;
804
805 if (ktype->read)
806 perm |= KEY_POS_READ | KEY_USR_READ;
807
808 if (ktype == &key_type_keyring || ktype->update)
809 perm |= KEY_USR_WRITE;
810 }
811
812 /* allocate a new key */
813 key = key_alloc(ktype, description, cred->fsuid, cred->fsgid, cred,
814 perm, flags);
815 if (IS_ERR(key)) {
816 key_ref = ERR_CAST(key);
817 goto error_3;
818 }
819
820 /* instantiate it and link it into the target keyring */
821 ret = __key_instantiate_and_link(key, payload, plen, keyring, NULL);
822 if (ret < 0) {
823 key_put(key);
824 key_ref = ERR_PTR(ret);
825 goto error_3;
826 }
827
828 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
829
830 error_3:
831 up_write(&keyring->sem);
832 error_2:
833 key_type_put(ktype);
834 error:
835 return key_ref;
836
837 found_matching_key:
838 /* we found a matching key, so we're going to try to update it
839 * - we can drop the locks first as we have the key pinned
840 */
841 up_write(&keyring->sem);
842 key_type_put(ktype);
843
844 key_ref = __key_update(key_ref, payload, plen);
845 goto error;
846
847 } /* end key_create_or_update() */
848
849 EXPORT_SYMBOL(key_create_or_update);
850
851 /*****************************************************************************/
852 /*
853 * update a key
854 */
855 int key_update(key_ref_t key_ref, const void *payload, size_t plen)
856 {
857 struct key *key = key_ref_to_ptr(key_ref);
858 int ret;
859
860 key_check(key);
861
862 /* the key must be writable */
863 ret = key_permission(key_ref, KEY_WRITE);
864 if (ret < 0)
865 goto error;
866
867 /* attempt to update it if supported */
868 ret = -EOPNOTSUPP;
869 if (key->type->update) {
870 down_write(&key->sem);
871
872 ret = key->type->update(key, payload, plen);
873 if (ret == 0)
874 /* updating a negative key instantiates it */
875 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
876
877 up_write(&key->sem);
878 }
879
880 error:
881 return ret;
882
883 } /* end key_update() */
884
885 EXPORT_SYMBOL(key_update);
886
887 /*****************************************************************************/
888 /*
889 * revoke a key
890 */
891 void key_revoke(struct key *key)
892 {
893 key_check(key);
894
895 /* make sure no one's trying to change or use the key when we mark it
896 * - we tell lockdep that we might nest because we might be revoking an
897 * authorisation key whilst holding the sem on a key we've just
898 * instantiated
899 */
900 down_write_nested(&key->sem, 1);
901 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
902 key->type->revoke)
903 key->type->revoke(key);
904
905 up_write(&key->sem);
906
907 } /* end key_revoke() */
908
909 EXPORT_SYMBOL(key_revoke);
910
911 /*****************************************************************************/
912 /*
913 * register a type of key
914 */
915 int register_key_type(struct key_type *ktype)
916 {
917 struct key_type *p;
918 int ret;
919
920 ret = -EEXIST;
921 down_write(&key_types_sem);
922
923 /* disallow key types with the same name */
924 list_for_each_entry(p, &key_types_list, link) {
925 if (strcmp(p->name, ktype->name) == 0)
926 goto out;
927 }
928
929 /* store the type */
930 list_add(&ktype->link, &key_types_list);
931 ret = 0;
932
933 out:
934 up_write(&key_types_sem);
935 return ret;
936
937 } /* end register_key_type() */
938
939 EXPORT_SYMBOL(register_key_type);
940
941 /*****************************************************************************/
942 /*
943 * unregister a type of key
944 */
945 void unregister_key_type(struct key_type *ktype)
946 {
947 struct rb_node *_n;
948 struct key *key;
949
950 down_write(&key_types_sem);
951
952 /* withdraw the key type */
953 list_del_init(&ktype->link);
954
955 /* mark all the keys of this type dead */
956 spin_lock(&key_serial_lock);
957
958 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
959 key = rb_entry(_n, struct key, serial_node);
960
961 if (key->type == ktype)
962 key->type = &key_type_dead;
963 }
964
965 spin_unlock(&key_serial_lock);
966
967 /* make sure everyone revalidates their keys */
968 synchronize_rcu();
969
970 /* we should now be able to destroy the payloads of all the keys of
971 * this type with impunity */
972 spin_lock(&key_serial_lock);
973
974 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
975 key = rb_entry(_n, struct key, serial_node);
976
977 if (key->type == ktype) {
978 if (ktype->destroy)
979 ktype->destroy(key);
980 memset(&key->payload, KEY_DESTROY, sizeof(key->payload));
981 }
982 }
983
984 spin_unlock(&key_serial_lock);
985 up_write(&key_types_sem);
986
987 } /* end unregister_key_type() */
988
989 EXPORT_SYMBOL(unregister_key_type);
990
991 /*****************************************************************************/
992 /*
993 * initialise the key management stuff
994 */
995 void __init key_init(void)
996 {
997 /* allocate a slab in which we can store keys */
998 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
999 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1000
1001 /* add the special key types */
1002 list_add_tail(&key_type_keyring.link, &key_types_list);
1003 list_add_tail(&key_type_dead.link, &key_types_list);
1004 list_add_tail(&key_type_user.link, &key_types_list);
1005
1006 /* record the root user tracking */
1007 rb_link_node(&root_key_user.node,
1008 NULL,
1009 &key_user_tree.rb_node);
1010
1011 rb_insert_color(&root_key_user.node,
1012 &key_user_tree);
1013
1014 } /* end key_init() */
1015
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