[PATCH] i386: i386 add Intel BTS cpufeature bit and detection (take 2)
[linux-2.6/x86.git] / security / keys / key.c
blob80de8c3e9cc3ea49c79e6525b0ce17b22076ac3e
1 /* key.c: basic authentication token and access key management
3 * Copyright (C) 2004-6 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
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"
23 static kmem_cache_t *key_jar;
24 struct rb_root key_serial_tree; /* tree of keys indexed by serial */
25 DEFINE_SPINLOCK(key_serial_lock);
27 struct rb_root key_user_tree; /* tree of quota records indexed by UID */
28 DEFINE_SPINLOCK(key_user_lock);
30 static LIST_HEAD(key_types_list);
31 static DECLARE_RWSEM(key_types_sem);
33 static void key_cleanup(void *data);
34 static DECLARE_WORK(key_cleanup_task, key_cleanup, NULL);
36 /* we serialise key instantiation and link */
37 DECLARE_RWSEM(key_construction_sem);
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",
44 #ifdef KEY_DEBUGGING
45 void __key_check(const struct key *key)
47 printk("__key_check: key %p {%08x} should be {%08x}\n",
48 key, key->magic, KEY_DEBUG_MAGIC);
49 BUG();
51 #endif
53 /*****************************************************************************/
55 * get the key quota record for a user, allocating a new record if one doesn't
56 * already exist
58 struct key_user *key_user_lookup(uid_t uid)
60 struct key_user *candidate = NULL, *user;
61 struct rb_node *parent = NULL;
62 struct rb_node **p;
64 try_again:
65 p = &key_user_tree.rb_node;
66 spin_lock(&key_user_lock);
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);
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;
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);
87 user = NULL;
88 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
89 if (unlikely(!candidate))
90 goto out;
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;
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 INIT_LIST_HEAD(&candidate->consq);
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;
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;
123 } /* end key_user_lookup() */
125 /*****************************************************************************/
127 * dispose of a user structure
129 void key_user_put(struct key_user *user)
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);
135 kfree(user);
138 } /* end key_user_put() */
140 /*****************************************************************************/
142 * insert a key with a fixed serial number
144 static void __init __key_insert_serial(struct key *key)
146 struct rb_node *parent, **p;
147 struct key *xkey;
149 parent = NULL;
150 p = &key_serial_tree.rb_node;
152 while (*p) {
153 parent = *p;
154 xkey = rb_entry(parent, struct key, serial_node);
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();
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);
168 } /* end __key_insert_serial() */
170 /*****************************************************************************/
172 * assign a key the next unique serial number
173 * - these are assigned randomly to avoid security issues through covert
174 * channel problems
176 static inline void key_alloc_serial(struct key *key)
178 struct rb_node *parent, **p;
179 struct key *xkey;
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));
186 key->serial >>= 1; /* negative numbers are not permitted */
187 } while (key->serial < 3);
189 spin_lock(&key_serial_lock);
191 parent = NULL;
192 p = &key_serial_tree.rb_node;
194 while (*p) {
195 parent = *p;
196 xkey = rb_entry(parent, struct key, serial_node);
198 if (key->serial < xkey->serial)
199 p = &(*p)->rb_left;
200 else if (key->serial > xkey->serial)
201 p = &(*p)->rb_right;
202 else
203 goto serial_exists;
205 goto insert_here;
207 /* we found a key with the proposed serial number - walk the tree from
208 * that point looking for the next unused serial number */
209 serial_exists:
210 for (;;) {
211 key->serial++;
212 if (key->serial < 2)
213 key->serial = 2;
215 if (!rb_parent(parent))
216 p = &key_serial_tree.rb_node;
217 else if (rb_parent(parent)->rb_left == parent)
218 p = &(rb_parent(parent)->rb_left);
219 else
220 p = &(rb_parent(parent)->rb_right);
222 parent = rb_next(parent);
223 if (!parent)
224 break;
226 xkey = rb_entry(parent, struct key, serial_node);
227 if (key->serial < xkey->serial)
228 goto insert_here;
231 /* we've found a suitable hole - arrange for this key to occupy it */
232 insert_here:
233 rb_link_node(&key->serial_node, parent, p);
234 rb_insert_color(&key->serial_node, &key_serial_tree);
236 spin_unlock(&key_serial_lock);
238 } /* end key_alloc_serial() */
240 /*****************************************************************************/
242 * allocate a key of the specified type
243 * - update the user's quota to reflect the existence of the key
244 * - called from a key-type operation with key_types_sem read-locked by
245 * key_create_or_update()
246 * - this prevents unregistration of the key type
247 * - upon return the key is as yet uninstantiated; the caller needs to either
248 * instantiate the key or discard it before returning
250 struct key *key_alloc(struct key_type *type, const char *desc,
251 uid_t uid, gid_t gid, struct task_struct *ctx,
252 key_perm_t perm, unsigned long flags)
254 struct key_user *user = NULL;
255 struct key *key;
256 size_t desclen, quotalen;
257 int ret;
259 key = ERR_PTR(-EINVAL);
260 if (!desc || !*desc)
261 goto error;
263 desclen = strlen(desc) + 1;
264 quotalen = desclen + type->def_datalen;
266 /* get hold of the key tracking for this user */
267 user = key_user_lookup(uid);
268 if (!user)
269 goto no_memory_1;
271 /* check that the user's quota permits allocation of another key and
272 * its description */
273 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
274 spin_lock(&user->lock);
275 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
276 if (user->qnkeys + 1 >= KEYQUOTA_MAX_KEYS ||
277 user->qnbytes + quotalen >= KEYQUOTA_MAX_BYTES
279 goto no_quota;
282 user->qnkeys++;
283 user->qnbytes += quotalen;
284 spin_unlock(&user->lock);
287 /* allocate and initialise the key and its description */
288 key = kmem_cache_alloc(key_jar, SLAB_KERNEL);
289 if (!key)
290 goto no_memory_2;
292 if (desc) {
293 key->description = kmalloc(desclen, GFP_KERNEL);
294 if (!key->description)
295 goto no_memory_3;
297 memcpy(key->description, desc, desclen);
300 atomic_set(&key->usage, 1);
301 init_rwsem(&key->sem);
302 key->type = type;
303 key->user = user;
304 key->quotalen = quotalen;
305 key->datalen = type->def_datalen;
306 key->uid = uid;
307 key->gid = gid;
308 key->perm = perm;
309 key->flags = 0;
310 key->expiry = 0;
311 key->payload.data = NULL;
312 key->security = NULL;
314 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
315 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
317 memset(&key->type_data, 0, sizeof(key->type_data));
319 #ifdef KEY_DEBUGGING
320 key->magic = KEY_DEBUG_MAGIC;
321 #endif
323 /* let the security module know about the key */
324 ret = security_key_alloc(key, ctx, flags);
325 if (ret < 0)
326 goto security_error;
328 /* publish the key by giving it a serial number */
329 atomic_inc(&user->nkeys);
330 key_alloc_serial(key);
332 error:
333 return key;
335 security_error:
336 kfree(key->description);
337 kmem_cache_free(key_jar, key);
338 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
339 spin_lock(&user->lock);
340 user->qnkeys--;
341 user->qnbytes -= quotalen;
342 spin_unlock(&user->lock);
344 key_user_put(user);
345 key = ERR_PTR(ret);
346 goto error;
348 no_memory_3:
349 kmem_cache_free(key_jar, key);
350 no_memory_2:
351 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
352 spin_lock(&user->lock);
353 user->qnkeys--;
354 user->qnbytes -= quotalen;
355 spin_unlock(&user->lock);
357 key_user_put(user);
358 no_memory_1:
359 key = ERR_PTR(-ENOMEM);
360 goto error;
362 no_quota:
363 spin_unlock(&user->lock);
364 key_user_put(user);
365 key = ERR_PTR(-EDQUOT);
366 goto error;
368 } /* end key_alloc() */
370 EXPORT_SYMBOL(key_alloc);
372 /*****************************************************************************/
374 * reserve an amount of quota for the key's payload
376 int key_payload_reserve(struct key *key, size_t datalen)
378 int delta = (int) datalen - key->datalen;
379 int ret = 0;
381 key_check(key);
383 /* contemplate the quota adjustment */
384 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
385 spin_lock(&key->user->lock);
387 if (delta > 0 &&
388 key->user->qnbytes + delta > KEYQUOTA_MAX_BYTES
390 ret = -EDQUOT;
392 else {
393 key->user->qnbytes += delta;
394 key->quotalen += delta;
396 spin_unlock(&key->user->lock);
399 /* change the recorded data length if that didn't generate an error */
400 if (ret == 0)
401 key->datalen = datalen;
403 return ret;
405 } /* end key_payload_reserve() */
407 EXPORT_SYMBOL(key_payload_reserve);
409 /*****************************************************************************/
411 * instantiate a key and link it into the target keyring atomically
412 * - called with the target keyring's semaphore writelocked
414 static int __key_instantiate_and_link(struct key *key,
415 const void *data,
416 size_t datalen,
417 struct key *keyring,
418 struct key *instkey)
420 int ret, awaken;
422 key_check(key);
423 key_check(keyring);
425 awaken = 0;
426 ret = -EBUSY;
428 down_write(&key_construction_sem);
430 /* can't instantiate twice */
431 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
432 /* instantiate the key */
433 ret = key->type->instantiate(key, data, datalen);
435 if (ret == 0) {
436 /* mark the key as being instantiated */
437 atomic_inc(&key->user->nikeys);
438 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
440 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
441 awaken = 1;
443 /* and link it into the destination keyring */
444 if (keyring)
445 ret = __key_link(keyring, key);
447 /* disable the authorisation key */
448 if (instkey)
449 key_revoke(instkey);
453 up_write(&key_construction_sem);
455 /* wake up anyone waiting for a key to be constructed */
456 if (awaken)
457 wake_up_all(&request_key_conswq);
459 return ret;
461 } /* end __key_instantiate_and_link() */
463 /*****************************************************************************/
465 * instantiate a key and link it into the target keyring atomically
467 int key_instantiate_and_link(struct key *key,
468 const void *data,
469 size_t datalen,
470 struct key *keyring,
471 struct key *instkey)
473 int ret;
475 if (keyring)
476 down_write(&keyring->sem);
478 ret = __key_instantiate_and_link(key, data, datalen, keyring, instkey);
480 if (keyring)
481 up_write(&keyring->sem);
483 return ret;
485 } /* end key_instantiate_and_link() */
487 EXPORT_SYMBOL(key_instantiate_and_link);
489 /*****************************************************************************/
491 * negatively instantiate a key and link it into the target keyring atomically
493 int key_negate_and_link(struct key *key,
494 unsigned timeout,
495 struct key *keyring,
496 struct key *instkey)
498 struct timespec now;
499 int ret, awaken;
501 key_check(key);
502 key_check(keyring);
504 awaken = 0;
505 ret = -EBUSY;
507 if (keyring)
508 down_write(&keyring->sem);
510 down_write(&key_construction_sem);
512 /* can't instantiate twice */
513 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
514 /* mark the key as being negatively instantiated */
515 atomic_inc(&key->user->nikeys);
516 set_bit(KEY_FLAG_NEGATIVE, &key->flags);
517 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
518 now = current_kernel_time();
519 key->expiry = now.tv_sec + timeout;
521 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
522 awaken = 1;
524 ret = 0;
526 /* and link it into the destination keyring */
527 if (keyring)
528 ret = __key_link(keyring, key);
530 /* disable the authorisation key */
531 if (instkey)
532 key_revoke(instkey);
535 up_write(&key_construction_sem);
537 if (keyring)
538 up_write(&keyring->sem);
540 /* wake up anyone waiting for a key to be constructed */
541 if (awaken)
542 wake_up_all(&request_key_conswq);
544 return ret;
546 } /* end key_negate_and_link() */
548 EXPORT_SYMBOL(key_negate_and_link);
550 /*****************************************************************************/
552 * do cleaning up in process context so that we don't have to disable
553 * interrupts all over the place
555 static void key_cleanup(void *data)
557 struct rb_node *_n;
558 struct key *key;
560 go_again:
561 /* look for a dead key in the tree */
562 spin_lock(&key_serial_lock);
564 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
565 key = rb_entry(_n, struct key, serial_node);
567 if (atomic_read(&key->usage) == 0)
568 goto found_dead_key;
571 spin_unlock(&key_serial_lock);
572 return;
574 found_dead_key:
575 /* we found a dead key - once we've removed it from the tree, we can
576 * drop the lock */
577 rb_erase(&key->serial_node, &key_serial_tree);
578 spin_unlock(&key_serial_lock);
580 key_check(key);
582 security_key_free(key);
584 /* deal with the user's key tracking and quota */
585 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
586 spin_lock(&key->user->lock);
587 key->user->qnkeys--;
588 key->user->qnbytes -= key->quotalen;
589 spin_unlock(&key->user->lock);
592 atomic_dec(&key->user->nkeys);
593 if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
594 atomic_dec(&key->user->nikeys);
596 key_user_put(key->user);
598 /* now throw away the key memory */
599 if (key->type->destroy)
600 key->type->destroy(key);
602 kfree(key->description);
604 #ifdef KEY_DEBUGGING
605 key->magic = KEY_DEBUG_MAGIC_X;
606 #endif
607 kmem_cache_free(key_jar, key);
609 /* there may, of course, be more than one key to destroy */
610 goto go_again;
612 } /* end key_cleanup() */
614 /*****************************************************************************/
616 * dispose of a reference to a key
617 * - when all the references are gone, we schedule the cleanup task to come and
618 * pull it out of the tree in definite process context
620 void key_put(struct key *key)
622 if (key) {
623 key_check(key);
625 if (atomic_dec_and_test(&key->usage))
626 schedule_work(&key_cleanup_task);
629 } /* end key_put() */
631 EXPORT_SYMBOL(key_put);
633 /*****************************************************************************/
635 * find a key by its serial number
637 struct key *key_lookup(key_serial_t id)
639 struct rb_node *n;
640 struct key *key;
642 spin_lock(&key_serial_lock);
644 /* search the tree for the specified key */
645 n = key_serial_tree.rb_node;
646 while (n) {
647 key = rb_entry(n, struct key, serial_node);
649 if (id < key->serial)
650 n = n->rb_left;
651 else if (id > key->serial)
652 n = n->rb_right;
653 else
654 goto found;
657 not_found:
658 key = ERR_PTR(-ENOKEY);
659 goto error;
661 found:
662 /* pretend it doesn't exist if it's dead */
663 if (atomic_read(&key->usage) == 0 ||
664 test_bit(KEY_FLAG_DEAD, &key->flags) ||
665 key->type == &key_type_dead)
666 goto not_found;
668 /* this races with key_put(), but that doesn't matter since key_put()
669 * doesn't actually change the key
671 atomic_inc(&key->usage);
673 error:
674 spin_unlock(&key_serial_lock);
675 return key;
677 } /* end key_lookup() */
679 /*****************************************************************************/
681 * find and lock the specified key type against removal
682 * - we return with the sem readlocked
684 struct key_type *key_type_lookup(const char *type)
686 struct key_type *ktype;
688 down_read(&key_types_sem);
690 /* look up the key type to see if it's one of the registered kernel
691 * types */
692 list_for_each_entry(ktype, &key_types_list, link) {
693 if (strcmp(ktype->name, type) == 0)
694 goto found_kernel_type;
697 up_read(&key_types_sem);
698 ktype = ERR_PTR(-ENOKEY);
700 found_kernel_type:
701 return ktype;
703 } /* end key_type_lookup() */
705 /*****************************************************************************/
707 * unlock a key type
709 void key_type_put(struct key_type *ktype)
711 up_read(&key_types_sem);
713 } /* end key_type_put() */
715 /*****************************************************************************/
717 * attempt to update an existing key
718 * - the key has an incremented refcount
719 * - we need to put the key if we get an error
721 static inline key_ref_t __key_update(key_ref_t key_ref,
722 const void *payload, size_t plen)
724 struct key *key = key_ref_to_ptr(key_ref);
725 int ret;
727 /* need write permission on the key to update it */
728 ret = key_permission(key_ref, KEY_WRITE);
729 if (ret < 0)
730 goto error;
732 ret = -EEXIST;
733 if (!key->type->update)
734 goto error;
736 down_write(&key->sem);
738 ret = key->type->update(key, payload, plen);
739 if (ret == 0)
740 /* updating a negative key instantiates it */
741 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
743 up_write(&key->sem);
745 if (ret < 0)
746 goto error;
747 out:
748 return key_ref;
750 error:
751 key_put(key);
752 key_ref = ERR_PTR(ret);
753 goto out;
755 } /* end __key_update() */
757 /*****************************************************************************/
759 * search the specified keyring for a key of the same description; if one is
760 * found, update it, otherwise add a new one
762 key_ref_t key_create_or_update(key_ref_t keyring_ref,
763 const char *type,
764 const char *description,
765 const void *payload,
766 size_t plen,
767 unsigned long flags)
769 struct key_type *ktype;
770 struct key *keyring, *key = NULL;
771 key_perm_t perm;
772 key_ref_t key_ref;
773 int ret;
775 /* look up the key type to see if it's one of the registered kernel
776 * types */
777 ktype = key_type_lookup(type);
778 if (IS_ERR(ktype)) {
779 key_ref = ERR_PTR(-ENODEV);
780 goto error;
783 key_ref = ERR_PTR(-EINVAL);
784 if (!ktype->match || !ktype->instantiate)
785 goto error_2;
787 keyring = key_ref_to_ptr(keyring_ref);
789 key_check(keyring);
791 key_ref = ERR_PTR(-ENOTDIR);
792 if (keyring->type != &key_type_keyring)
793 goto error_2;
795 down_write(&keyring->sem);
797 /* if we're going to allocate a new key, we're going to have
798 * to modify the keyring */
799 ret = key_permission(keyring_ref, KEY_WRITE);
800 if (ret < 0) {
801 key_ref = ERR_PTR(ret);
802 goto error_3;
805 /* if it's possible to update this type of key, search for an existing
806 * key of the same type and description in the destination keyring and
807 * update that instead if possible
809 if (ktype->update) {
810 key_ref = __keyring_search_one(keyring_ref, ktype, description,
812 if (!IS_ERR(key_ref))
813 goto found_matching_key;
816 /* decide on the permissions we want */
817 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
818 perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR;
820 if (ktype->read)
821 perm |= KEY_POS_READ | KEY_USR_READ;
823 if (ktype == &key_type_keyring || ktype->update)
824 perm |= KEY_USR_WRITE;
826 /* allocate a new key */
827 key = key_alloc(ktype, description, current->fsuid, current->fsgid,
828 current, perm, flags);
829 if (IS_ERR(key)) {
830 key_ref = ERR_PTR(PTR_ERR(key));
831 goto error_3;
834 /* instantiate it and link it into the target keyring */
835 ret = __key_instantiate_and_link(key, payload, plen, keyring, NULL);
836 if (ret < 0) {
837 key_put(key);
838 key_ref = ERR_PTR(ret);
839 goto error_3;
842 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
844 error_3:
845 up_write(&keyring->sem);
846 error_2:
847 key_type_put(ktype);
848 error:
849 return key_ref;
851 found_matching_key:
852 /* we found a matching key, so we're going to try to update it
853 * - we can drop the locks first as we have the key pinned
855 up_write(&keyring->sem);
856 key_type_put(ktype);
858 key_ref = __key_update(key_ref, payload, plen);
859 goto error;
861 } /* end key_create_or_update() */
863 EXPORT_SYMBOL(key_create_or_update);
865 /*****************************************************************************/
867 * update a key
869 int key_update(key_ref_t key_ref, const void *payload, size_t plen)
871 struct key *key = key_ref_to_ptr(key_ref);
872 int ret;
874 key_check(key);
876 /* the key must be writable */
877 ret = key_permission(key_ref, KEY_WRITE);
878 if (ret < 0)
879 goto error;
881 /* attempt to update it if supported */
882 ret = -EOPNOTSUPP;
883 if (key->type->update) {
884 down_write(&key->sem);
886 ret = key->type->update(key, payload, plen);
887 if (ret == 0)
888 /* updating a negative key instantiates it */
889 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
891 up_write(&key->sem);
894 error:
895 return ret;
897 } /* end key_update() */
899 EXPORT_SYMBOL(key_update);
901 /*****************************************************************************/
903 * revoke a key
905 void key_revoke(struct key *key)
907 key_check(key);
909 /* make sure no one's trying to change or use the key when we mark
910 * it */
911 down_write(&key->sem);
912 set_bit(KEY_FLAG_REVOKED, &key->flags);
914 if (key->type->revoke)
915 key->type->revoke(key);
917 up_write(&key->sem);
919 } /* end key_revoke() */
921 EXPORT_SYMBOL(key_revoke);
923 /*****************************************************************************/
925 * register a type of key
927 int register_key_type(struct key_type *ktype)
929 struct key_type *p;
930 int ret;
932 ret = -EEXIST;
933 down_write(&key_types_sem);
935 /* disallow key types with the same name */
936 list_for_each_entry(p, &key_types_list, link) {
937 if (strcmp(p->name, ktype->name) == 0)
938 goto out;
941 /* store the type */
942 list_add(&ktype->link, &key_types_list);
943 ret = 0;
945 out:
946 up_write(&key_types_sem);
947 return ret;
949 } /* end register_key_type() */
951 EXPORT_SYMBOL(register_key_type);
953 /*****************************************************************************/
955 * unregister a type of key
957 void unregister_key_type(struct key_type *ktype)
959 struct rb_node *_n;
960 struct key *key;
962 down_write(&key_types_sem);
964 /* withdraw the key type */
965 list_del_init(&ktype->link);
967 /* mark all the keys of this type dead */
968 spin_lock(&key_serial_lock);
970 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
971 key = rb_entry(_n, struct key, serial_node);
973 if (key->type == ktype)
974 key->type = &key_type_dead;
977 spin_unlock(&key_serial_lock);
979 /* make sure everyone revalidates their keys */
980 synchronize_rcu();
982 /* we should now be able to destroy the payloads of all the keys of
983 * this type with impunity */
984 spin_lock(&key_serial_lock);
986 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
987 key = rb_entry(_n, struct key, serial_node);
989 if (key->type == ktype) {
990 if (ktype->destroy)
991 ktype->destroy(key);
992 memset(&key->payload, KEY_DESTROY, sizeof(key->payload));
996 spin_unlock(&key_serial_lock);
997 up_write(&key_types_sem);
999 } /* end unregister_key_type() */
1001 EXPORT_SYMBOL(unregister_key_type);
1003 /*****************************************************************************/
1005 * initialise the key management stuff
1007 void __init key_init(void)
1009 /* allocate a slab in which we can store keys */
1010 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1011 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1013 /* add the special key types */
1014 list_add_tail(&key_type_keyring.link, &key_types_list);
1015 list_add_tail(&key_type_dead.link, &key_types_list);
1016 list_add_tail(&key_type_user.link, &key_types_list);
1018 /* record the root user tracking */
1019 rb_link_node(&root_key_user.node,
1020 NULL,
1021 &key_user_tree.rb_node);
1023 rb_insert_color(&root_key_user.node,
1024 &key_user_tree);
1026 /* record root's user standard keyrings */
1027 key_check(&root_user_keyring);
1028 key_check(&root_session_keyring);
1030 __key_insert_serial(&root_user_keyring);
1031 __key_insert_serial(&root_session_keyring);
1033 keyring_publish_name(&root_user_keyring);
1034 keyring_publish_name(&root_session_keyring);
1036 /* link the two root keyrings together */
1037 key_link(&root_session_keyring, &root_user_keyring);
1039 } /* end key_init() */