1 /* key.c: basic authentication token and access key management
2 *
3 * Copyright (C) 2004 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/sched.h>
15 #include <linux/slab.h>
16 #include <linux/workqueue.h>
17 #include <linux/err.h>
18 #include "internal.h"
19
20 static kmem_cache_t *key_jar;
21 static key_serial_t key_serial_next = 3;
22 struct rb_root key_serial_tree; /* tree of keys indexed by serial */
23 DEFINE_SPINLOCK(key_serial_lock);
24
25 struct rb_root key_user_tree; /* tree of quota records indexed by UID */
26 DEFINE_SPINLOCK(key_user_lock);
27
28 static LIST_HEAD(key_types_list);
29 static DECLARE_RWSEM(key_types_sem);
30
31 static void key_cleanup(void *data);
32 static DECLARE_WORK(key_cleanup_task, key_cleanup, NULL);
33
34 /* we serialise key instantiation and link */
35 DECLARE_RWSEM(key_construction_sem);
36
37 /* any key who's type gets unegistered will be re-typed to this */
38 struct key_type key_type_dead = {
39 .name = "dead",
40 };
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 /*
53 * get the key quota record for a user, allocating a new record if one doesn't
54 * already exist
55 */
56 struct key_user *key_user_lookup(uid_t uid)
57 {
58 struct key_user *candidate = NULL, *user;
59 struct rb_node *parent = NULL;
60 struct rb_node **p;
61
62 try_again:
63 p = &key_user_tree.rb_node;
64 spin_lock(&key_user_lock);
65
66 /* search the tree for a user record with a matching UID */
67 while (*p) {
68 parent = *p;
69 user = rb_entry(parent, struct key_user, node);
70
71 if (uid < user->uid)
72 p = &(*p)->rb_left;
73 else if (uid > user->uid)
74 p = &(*p)->rb_right;
75 else
76 goto found;
77 }
78
79 /* if we get here, we failed to find a match in the tree */
80 if (!candidate) {
81 /* allocate a candidate user record if we don't already have
82 * one */
83 spin_unlock(&key_user_lock);
84
85 user = NULL;
86 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
87 if (unlikely(!candidate))
88 goto out;
89
90 /* the allocation may have scheduled, so we need to repeat the
91 * search lest someone else added the record whilst we were
92 * asleep */
93 goto try_again;
94 }
95
96 /* if we get here, then the user record still hadn't appeared on the
97 * second pass - so we use the candidate record */
98 atomic_set(&candidate->usage, 1);
99 atomic_set(&candidate->nkeys, 0);
100 atomic_set(&candidate->nikeys, 0);
101 candidate->uid = uid;
102 candidate->qnkeys = 0;
103 candidate->qnbytes = 0;
104 spin_lock_init(&candidate->lock);
105 INIT_LIST_HEAD(&candidate->consq);
106
107 rb_link_node(&candidate->node, parent, p);
108 rb_insert_color(&candidate->node, &key_user_tree);
109 spin_unlock(&key_user_lock);
110 user = candidate;
111 goto out;
112
113 /* okay - we found a user record for this UID */
114 found:
115 atomic_inc(&user->usage);
116 spin_unlock(&key_user_lock);
117 if (candidate)
118 kfree(candidate);
119 out:
120 return user;
121
122 } /* end key_user_lookup() */
123
124 /*****************************************************************************/
125 /*
126 * dispose of a user structure
127 */
128 void key_user_put(struct key_user *user)
129 {
130 if (atomic_dec_and_lock(&user->usage, &key_user_lock)) {
131 rb_erase(&user->node, &key_user_tree);
132 spin_unlock(&key_user_lock);
133
134 kfree(user);
135 }
136
137 } /* end key_user_put() */
138
139 /*****************************************************************************/
140 /*
141 * insert a key with a fixed serial number
142 */
143 static void __init __key_insert_serial(struct key *key)
144 {
145 struct rb_node *parent, **p;
146 struct key *xkey;
147
148 parent = NULL;
149 p = &key_serial_tree.rb_node;
150
151 while (*p) {
152 parent = *p;
153 xkey = rb_entry(parent, struct key, serial_node);
154
155 if (key->serial < xkey->serial)
156 p = &(*p)->rb_left;
157 else if (key->serial > xkey->serial)
158 p = &(*p)->rb_right;
159 else
160 BUG();
161 }
162
163 /* we've found a suitable hole - arrange for this key to occupy it */
164 rb_link_node(&key->serial_node, parent, p);
165 rb_insert_color(&key->serial_node, &key_serial_tree);
166
167 } /* end __key_insert_serial() */
168
169 /*****************************************************************************/
170 /*
171 * assign a key the next unique serial number
172 * - we work through all the serial numbers between 2 and 2^31-1 in turn and
173 * then wrap
174 */
175 static inline void key_alloc_serial(struct key *key)
176 {
177 struct rb_node *parent, **p;
178 struct key *xkey;
179
180 spin_lock(&key_serial_lock);
181
182 /* propose a likely serial number and look for a hole for it in the
183 * serial number tree */
184 key->serial = key_serial_next;
185 if (key->serial < 3)
186 key->serial = 3;
187 key_serial_next = key->serial + 1;
188
189 parent = NULL;
190 p = &key_serial_tree.rb_node;
191
192 while (*p) {
193 parent = *p;
194 xkey = rb_entry(parent, struct key, serial_node);
195
196 if (key->serial < xkey->serial)
197 p = &(*p)->rb_left;
198 else if (key->serial > xkey->serial)
199 p = &(*p)->rb_right;
200 else
201 goto serial_exists;
202 }
203 goto insert_here;
204
205 /* we found a key with the proposed serial number - walk the tree from
206 * that point looking for the next unused serial number */
207 serial_exists:
208 for (;;) {
209 key->serial = key_serial_next;
210 if (key->serial < 2)
211 key->serial = 2;
212 key_serial_next = key->serial + 1;
213
214 if (!parent->rb_parent)
215 p = &key_serial_tree.rb_node;
216 else if (parent->rb_parent->rb_left == parent)
217 p = &parent->rb_parent->rb_left;
218 else
219 p = &parent->rb_parent->rb_right;
220
221 parent = rb_next(parent);
222 if (!parent)
223 break;
224
225 xkey = rb_entry(parent, struct key, serial_node);
226 if (key->serial < xkey->serial)
227 goto insert_here;
228 }
229
230 /* we've found a suitable hole - arrange for this key to occupy it */
231 insert_here:
232 rb_link_node(&key->serial_node, parent, p);
233 rb_insert_color(&key->serial_node, &key_serial_tree);
234
235 spin_unlock(&key_serial_lock);
236
237 } /* end key_alloc_serial() */
238
239 /*****************************************************************************/
240 /*
241 * allocate a key of the specified type
242 * - update the user's quota to reflect the existence of the key
243 * - called from a key-type operation with key_types_sem read-locked by either
244 * key_create_or_update() or by key_duplicate(); this prevents unregistration
245 * of the key type
246 * - upon return the key is as yet uninstantiated; the caller needs to either
247 * instantiate the key or discard it before returning
248 */
249 struct key *key_alloc(struct key_type *type, const char *desc,
250 uid_t uid, gid_t gid, key_perm_t perm,
251 int not_in_quota)
252 {
253 struct key_user *user = NULL;
254 struct key *key;
255 size_t desclen, quotalen;
256
257 key = ERR_PTR(-EINVAL);
258 if (!desc || !*desc)
259 goto error;
260
261 desclen = strlen(desc) + 1;
262 quotalen = desclen + type->def_datalen;
263
264 /* get hold of the key tracking for this user */
265 user = key_user_lookup(uid);
266 if (!user)
267 goto no_memory_1;
268
269 /* check that the user's quota permits allocation of another key and
270 * its description */
271 if (!not_in_quota) {
272 spin_lock(&user->lock);
273 if (user->qnkeys + 1 >= KEYQUOTA_MAX_KEYS &&
274 user->qnbytes + quotalen >= KEYQUOTA_MAX_BYTES
275 )
276 goto no_quota;
277
278 user->qnkeys++;
279 user->qnbytes += quotalen;
280 spin_unlock(&user->lock);
281 }
282
283 /* allocate and initialise the key and its description */
284 key = kmem_cache_alloc(key_jar, SLAB_KERNEL);
285 if (!key)
286 goto no_memory_2;
287
288 if (desc) {
289 key->description = kmalloc(desclen, GFP_KERNEL);
290 if (!key->description)
291 goto no_memory_3;
292
293 memcpy(key->description, desc, desclen);
294 }
295
296 atomic_set(&key->usage, 1);
297 rwlock_init(&key->lock);
298 init_rwsem(&key->sem);
299 key->type = type;
300 key->user = user;
301 key->quotalen = quotalen;
302 key->datalen = type->def_datalen;
303 key->uid = uid;
304 key->gid = gid;
305 key->perm = perm;
306 key->flags = 0;
307 key->expiry = 0;
308 key->payload.data = NULL;
309
310 if (!not_in_quota)
311 key->flags |= KEY_FLAG_IN_QUOTA;
312
313 memset(&key->type_data, 0, sizeof(key->type_data));
314
315 #ifdef KEY_DEBUGGING
316 key->magic = KEY_DEBUG_MAGIC;
317 #endif
318
319 /* publish the key by giving it a serial number */
320 atomic_inc(&user->nkeys);
321 key_alloc_serial(key);
322
323 error:
324 return key;
325
326 no_memory_3:
327 kmem_cache_free(key_jar, key);
328 no_memory_2:
329 if (!not_in_quota) {
330 spin_lock(&user->lock);
331 user->qnkeys--;
332 user->qnbytes -= quotalen;
333 spin_unlock(&user->lock);
334 }
335 key_user_put(user);
336 no_memory_1:
337 key = ERR_PTR(-ENOMEM);
338 goto error;
339
340 no_quota:
341 spin_unlock(&user->lock);
342 key_user_put(user);
343 key = ERR_PTR(-EDQUOT);
344 goto error;
345
346 } /* end key_alloc() */
347
348 EXPORT_SYMBOL(key_alloc);
349
350 /*****************************************************************************/
351 /*
352 * reserve an amount of quota for the key's payload
353 */
354 int key_payload_reserve(struct key *key, size_t datalen)
355 {
356 int delta = (int) datalen - key->datalen;
357 int ret = 0;
358
359 key_check(key);
360
361 /* contemplate the quota adjustment */
362 if (delta != 0 && key->flags & KEY_FLAG_IN_QUOTA) {
363 spin_lock(&key->user->lock);
364
365 if (delta > 0 &&
366 key->user->qnbytes + delta > KEYQUOTA_MAX_BYTES
367 ) {
368 ret = -EDQUOT;
369 }
370 else {
371 key->user->qnbytes += delta;
372 key->quotalen += delta;
373 }
374 spin_unlock(&key->user->lock);
375 }
376
377 /* change the recorded data length if that didn't generate an error */
378 if (ret == 0)
379 key->datalen = datalen;
380
381 return ret;
382
383 } /* end key_payload_reserve() */
384
385 EXPORT_SYMBOL(key_payload_reserve);
386
387 /*****************************************************************************/
388 /*
389 * instantiate a key and link it into the target keyring atomically
390 * - called with the target keyring's semaphore writelocked
391 */
392 static int __key_instantiate_and_link(struct key *key,
393 const void *data,
394 size_t datalen,
395 struct key *keyring)
396 {
397 int ret, awaken;
398
399 key_check(key);
400 key_check(keyring);
401
402 awaken = 0;
403 ret = -EBUSY;
404
405 down_write(&key_construction_sem);
406
407 /* can't instantiate twice */
408 if (!(key->flags & KEY_FLAG_INSTANTIATED)) {
409 /* instantiate the key */
410 ret = key->type->instantiate(key, data, datalen);
411
412 if (ret == 0) {
413 /* mark the key as being instantiated */
414 write_lock(&key->lock);
415
416 atomic_inc(&key->user->nikeys);
417 key->flags |= KEY_FLAG_INSTANTIATED;
418
419 if (key->flags & KEY_FLAG_USER_CONSTRUCT) {
420 key->flags &= ~KEY_FLAG_USER_CONSTRUCT;
421 awaken = 1;
422 }
423
424 write_unlock(&key->lock);
425
426 /* and link it into the destination keyring */
427 if (keyring)
428 ret = __key_link(keyring, key);
429 }
430 }
431
432 up_write(&key_construction_sem);
433
434 /* wake up anyone waiting for a key to be constructed */
435 if (awaken)
436 wake_up_all(&request_key_conswq);
437
438 return ret;
439
440 } /* end __key_instantiate_and_link() */
441
442 /*****************************************************************************/
443 /*
444 * instantiate a key and link it into the target keyring atomically
445 */
446 int key_instantiate_and_link(struct key *key,
447 const void *data,
448 size_t datalen,
449 struct key *keyring)
450 {
451 int ret;
452
453 if (keyring)
454 down_write(&keyring->sem);
455
456 ret = __key_instantiate_and_link(key, data, datalen, keyring);
457
458 if (keyring)
459 up_write(&keyring->sem);
460
461 return ret;
462 } /* end key_instantiate_and_link() */
463
464 EXPORT_SYMBOL(key_instantiate_and_link);
465
466 /*****************************************************************************/
467 /*
468 * negatively instantiate a key and link it into the target keyring atomically
469 */
470 int key_negate_and_link(struct key *key,
471 unsigned timeout,
472 struct key *keyring)
473 {
474 struct timespec now;
475 int ret, awaken;
476
477 key_check(key);
478 key_check(keyring);
479
480 awaken = 0;
481 ret = -EBUSY;
482
483 if (keyring)
484 down_write(&keyring->sem);
485
486 down_write(&key_construction_sem);
487
488 /* can't instantiate twice */
489 if (!(key->flags & KEY_FLAG_INSTANTIATED)) {
490 /* mark the key as being negatively instantiated */
491 write_lock(&key->lock);
492
493 atomic_inc(&key->user->nikeys);
494 key->flags |= KEY_FLAG_INSTANTIATED | KEY_FLAG_NEGATIVE;
495 now = current_kernel_time();
496 key->expiry = now.tv_sec + timeout;
497
498 if (key->flags & KEY_FLAG_USER_CONSTRUCT) {
499 key->flags &= ~KEY_FLAG_USER_CONSTRUCT;
500 awaken = 1;
501 }
502
503 write_unlock(&key->lock);
504 ret = 0;
505
506 /* and link it into the destination keyring */
507 if (keyring)
508 ret = __key_link(keyring, key);
509 }
510
511 up_write(&key_construction_sem);
512
513 if (keyring)
514 up_write(&keyring->sem);
515
516 /* wake up anyone waiting for a key to be constructed */
517 if (awaken)
518 wake_up_all(&request_key_conswq);
519
520 return ret;
521
522 } /* end key_negate_and_link() */
523
524 EXPORT_SYMBOL(key_negate_and_link);
525
526 /*****************************************************************************/
527 /*
528 * do cleaning up in process context so that we don't have to disable
529 * interrupts all over the place
530 */
531 static void key_cleanup(void *data)
532 {
533 struct rb_node *_n;
534 struct key *key;
535
536 go_again:
537 /* look for a dead key in the tree */
538 spin_lock(&key_serial_lock);
539
540 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
541 key = rb_entry(_n, struct key, serial_node);
542
543 if (atomic_read(&key->usage) == 0)
544 goto found_dead_key;
545 }
546
547 spin_unlock(&key_serial_lock);
548 return;
549
550 found_dead_key:
551 /* we found a dead key - once we've removed it from the tree, we can
552 * drop the lock */
553 rb_erase(&key->serial_node, &key_serial_tree);
554 spin_unlock(&key_serial_lock);
555
556 /* deal with the user's key tracking and quota */
557 if (key->flags & KEY_FLAG_IN_QUOTA) {
558 spin_lock(&key->user->lock);
559 key->user->qnkeys--;
560 key->user->qnbytes -= key->quotalen;
561 spin_unlock(&key->user->lock);
562 }
563
564 atomic_dec(&key->user->nkeys);
565 if (key->flags & KEY_FLAG_INSTANTIATED)
566 atomic_dec(&key->user->nikeys);
567
568 key_user_put(key->user);
569
570 /* now throw away the key memory */
571 if (key->type->destroy)
572 key->type->destroy(key);
573
574 kfree(key->description);
575
576 #ifdef KEY_DEBUGGING
577 key->magic = KEY_DEBUG_MAGIC_X;
578 #endif
579 kmem_cache_free(key_jar, key);
580
581 /* there may, of course, be more than one key to destroy */
582 goto go_again;
583
584 } /* end key_cleanup() */
585
586 /*****************************************************************************/
587 /*
588 * dispose of a reference to a key
589 * - when all the references are gone, we schedule the cleanup task to come and
590 * pull it out of the tree in definite process context
591 */
592 void key_put(struct key *key)
593 {
594 if (key) {
595 key_check(key);
596
597 if (atomic_dec_and_test(&key->usage))
598 schedule_work(&key_cleanup_task);
599 }
600
601 } /* end key_put() */
602
603 EXPORT_SYMBOL(key_put);
604
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 /* pretent doesn't exist if it's dead */
635 if (atomic_read(&key->usage) == 0 ||
636 (key->flags & KEY_FLAG_DEAD) ||
637 key->type == &key_type_dead)
638 goto not_found;
639
640 /* this races with key_put(), but that doesn't matter since key_put()
641 * doesn't actually change the key
642 */
643 atomic_inc(&key->usage);
644
645 error:
646 spin_unlock(&key_serial_lock);
647 return key;
648
649 } /* end key_lookup() */
650
651 /*****************************************************************************/
652 /*
653 * find and lock the specified key type against removal
654 * - we return with the sem readlocked
655 */
656 struct key_type *key_type_lookup(const char *type)
657 {
658 struct key_type *ktype;
659
660 down_read(&key_types_sem);
661
662 /* look up the key type to see if it's one of the registered kernel
663 * types */
664 list_for_each_entry(ktype, &key_types_list, link) {
665 if (strcmp(ktype->name, type) == 0)
666 goto found_kernel_type;
667 }
668
669 up_read(&key_types_sem);
670 ktype = ERR_PTR(-ENOKEY);
671
672 found_kernel_type:
673 return ktype;
674
675 } /* end key_type_lookup() */
676
677 /*****************************************************************************/
678 /*
679 * unlock a key type
680 */
681 void key_type_put(struct key_type *ktype)
682 {
683 up_read(&key_types_sem);
684
685 } /* end key_type_put() */
686
687 /*****************************************************************************/
688 /*
689 * attempt to update an existing key
690 * - the key has an incremented refcount
691 * - we need to put the key if we get an error
692 */
693 static inline struct key *__key_update(struct key *key, const void *payload,
694 size_t plen)
695 {
696 int ret;
697
698 /* need write permission on the key to update it */
699 ret = -EACCES;
700 if (!key_permission(key, KEY_WRITE))
701 goto error;
702
703 ret = -EEXIST;
704 if (!key->type->update)
705 goto error;
706
707 down_write(&key->sem);
708
709 ret = key->type->update(key, payload, plen);
710
711 if (ret == 0) {
712 /* updating a negative key instantiates it */
713 write_lock(&key->lock);
714 key->flags &= ~KEY_FLAG_NEGATIVE;
715 write_unlock(&key->lock);
716 }
717
718 up_write(&key->sem);
719
720 if (ret < 0)
721 goto error;
722 out:
723 return key;
724
725 error:
726 key_put(key);
727 key = ERR_PTR(ret);
728 goto out;
729
730 } /* end __key_update() */
731
732 /*****************************************************************************/
733 /*
734 * search the specified keyring for a key of the same description; if one is
735 * found, update it, otherwise add a new one
736 */
737 struct key *key_create_or_update(struct key *keyring,
738 const char *type,
739 const char *description,
740 const void *payload,
741 size_t plen,
742 int not_in_quota)
743 {
744 struct key_type *ktype;
745 struct key *key = NULL;
746 key_perm_t perm;
747 int ret;
748
749 key_check(keyring);
750
751 /* look up the key type to see if it's one of the registered kernel
752 * types */
753 ktype = key_type_lookup(type);
754 if (IS_ERR(ktype)) {
755 key = ERR_PTR(-ENODEV);
756 goto error;
757 }
758
759 ret = -EINVAL;
760 if (!ktype->match || !ktype->instantiate)
761 goto error_2;
762
763 /* search for an existing key of the same type and description in the
764 * destination keyring
765 */
766 down_write(&keyring->sem);
767
768 key = __keyring_search_one(keyring, ktype, description, 0);
769 if (!IS_ERR(key))
770 goto found_matching_key;
771
772 /* if we're going to allocate a new key, we're going to have to modify
773 * the keyring */
774 ret = -EACCES;
775 if (!key_permission(keyring, KEY_WRITE))
776 goto error_3;
777
778 /* decide on the permissions we want */
779 perm = KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK;
780
781 if (ktype->read)
782 perm |= KEY_USR_READ;
783
784 if (ktype == &key_type_keyring || ktype->update)
785 perm |= KEY_USR_WRITE;
786
787 /* allocate a new key */
788 key = key_alloc(ktype, description, current->fsuid, current->fsgid,
789 perm, not_in_quota);
790 if (IS_ERR(key)) {
791 ret = PTR_ERR(key);
792 goto error_3;
793 }
794
795 /* instantiate it and link it into the target keyring */
796 ret = __key_instantiate_and_link(key, payload, plen, keyring);
797 if (ret < 0) {
798 key_put(key);
799 key = ERR_PTR(ret);
800 }
801
802 error_3:
803 up_write(&keyring->sem);
804 error_2:
805 key_type_put(ktype);
806 error:
807 return key;
808
809 found_matching_key:
810 /* we found a matching key, so we're going to try to update it
811 * - we can drop the locks first as we have the key pinned
812 */
813 up_write(&keyring->sem);
814 key_type_put(ktype);
815
816 key = __key_update(key, payload, plen);
817 goto error;
818
819 } /* end key_create_or_update() */
820
821 EXPORT_SYMBOL(key_create_or_update);
822
823 /*****************************************************************************/
824 /*
825 * update a key
826 */
827 int key_update(struct key *key, const void *payload, size_t plen)
828 {
829 int ret;
830
831 key_check(key);
832
833 /* the key must be writable */
834 ret = -EACCES;
835 if (!key_permission(key, KEY_WRITE))
836 goto error;
837
838 /* attempt to update it if supported */
839 ret = -EOPNOTSUPP;
840 if (key->type->update) {
841 down_write(&key->sem);
842 ret = key->type->update(key, payload, plen);
843
844 if (ret == 0) {
845 /* updating a negative key instantiates it */
846 write_lock(&key->lock);
847 key->flags &= ~KEY_FLAG_NEGATIVE;
848 write_unlock(&key->lock);
849 }
850
851 up_write(&key->sem);
852 }
853
854 error:
855 return ret;
856
857 } /* end key_update() */
858
859 EXPORT_SYMBOL(key_update);
860
861 /*****************************************************************************/
862 /*
863 * duplicate a key, potentially with a revised description
864 * - must be supported by the keytype (keyrings for instance can be duplicated)
865 */
866 struct key *key_duplicate(struct key *source, const char *desc)
867 {
868 struct key *key;
869 int ret;
870
871 key_check(source);
872
873 if (!desc)
874 desc = source->description;
875
876 down_read(&key_types_sem);
877
878 ret = -EINVAL;
879 if (!source->type->duplicate)
880 goto error;
881
882 /* allocate and instantiate a key */
883 key = key_alloc(source->type, desc, current->fsuid, current->fsgid,
884 source->perm, 0);
885 if (IS_ERR(key))
886 goto error_k;
887
888 down_read(&source->sem);
889 ret = key->type->duplicate(key, source);
890 up_read(&source->sem);
891 if (ret < 0)
892 goto error2;
893
894 atomic_inc(&key->user->nikeys);
895
896 write_lock(&key->lock);
897 key->flags |= KEY_FLAG_INSTANTIATED;
898 write_unlock(&key->lock);
899
900 error_k:
901 up_read(&key_types_sem);
902 out:
903 return key;
904
905 error2:
906 key_put(key);
907 error:
908 up_read(&key_types_sem);
909 key = ERR_PTR(ret);
910 goto out;
911
912 } /* end key_duplicate() */
913
914 /*****************************************************************************/
915 /*
916 * revoke a key
917 */
918 void key_revoke(struct key *key)
919 {
920 key_check(key);
921
922 /* make sure no one's trying to change or use the key when we mark
923 * it */
924 down_write(&key->sem);
925 write_lock(&key->lock);
926 key->flags |= KEY_FLAG_REVOKED;
927 write_unlock(&key->lock);
928 up_write(&key->sem);
929
930 } /* end key_revoke() */
931
932 EXPORT_SYMBOL(key_revoke);
933
934 /*****************************************************************************/
935 /*
936 * register a type of key
937 */
938 int register_key_type(struct key_type *ktype)
939 {
940 struct key_type *p;
941 int ret;
942
943 ret = -EEXIST;
944 down_write(&key_types_sem);
945
946 /* disallow key types with the same name */
947 list_for_each_entry(p, &key_types_list, link) {
948 if (strcmp(p->name, ktype->name) == 0)
949 goto out;
950 }
951
952 /* store the type */
953 list_add(&ktype->link, &key_types_list);
954 ret = 0;
955
956 out:
957 up_write(&key_types_sem);
958 return ret;
959
960 } /* end register_key_type() */
961
962 EXPORT_SYMBOL(register_key_type);
963
964 /*****************************************************************************/
965 /*
966 * unregister a type of key
967 */
968 void unregister_key_type(struct key_type *ktype)
969 {
970 struct rb_node *_n;
971 struct key *key;
972
973 down_write(&key_types_sem);
974
975 /* withdraw the key type */
976 list_del_init(&ktype->link);
977
978 /* need to withdraw all keys of this type */
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 continue;
986
987 write_lock(&key->lock);
988 key->type = &key_type_dead;
989 write_unlock(&key->lock);
990
991 /* there shouldn't be anyone looking at the description or
992 * payload now */
993 if (ktype->destroy)
994 ktype->destroy(key);
995 memset(&key->payload, 0xbd, sizeof(key->payload));
996 }
997
998 spin_unlock(&key_serial_lock);
999 up_write(&key_types_sem);
1000
1001 } /* end unregister_key_type() */
1002
1003 EXPORT_SYMBOL(unregister_key_type);
1004
1005 /*****************************************************************************/
1006 /*
1007 * initialise the key management stuff
1008 */
1009 void __init key_init(void)
1010 {
1011 /* allocate a slab in which we can store keys */
1012 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1013 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1014
1015 /* add the special key types */
1016 list_add_tail(&key_type_keyring.link, &key_types_list);
1017 list_add_tail(&key_type_dead.link, &key_types_list);
1018 list_add_tail(&key_type_user.link, &key_types_list);
1019
1020 /* record the root user tracking */
1021 rb_link_node(&root_key_user.node,
1022 NULL,
1023 &key_user_tree.rb_node);
1024
1025 rb_insert_color(&root_key_user.node,
1026 &key_user_tree);
1027
1028 /* record root's user standard keyrings */
1029 key_check(&root_user_keyring);
1030 key_check(&root_session_keyring);
1031
1032 __key_insert_serial(&root_user_keyring);
1033 __key_insert_serial(&root_session_keyring);
1034
1035 keyring_publish_name(&root_user_keyring);
1036 keyring_publish_name(&root_session_keyring);
1037
1038 /* link the two root keyrings together */
1039 key_link(&root_session_keyring, &root_user_keyring);
1040 } /* end key_init() */
1041
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