1 /* Basic authentication token and access key management
2 *
3 * Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/poison.h>
15 #include <linux/sched.h>
16 #include <linux/slab.h>
17 #include <linux/security.h>
18 #include <linux/workqueue.h>
19 #include <linux/random.h>
20 #include <linux/err.h>
21 #include "internal.h"
22
23 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 unsigned int key_quota_root_maxkeys = 200; /* root's key count quota */
31 unsigned int key_quota_root_maxbytes = 20000; /* root's key space quota */
32 unsigned int key_quota_maxkeys = 200; /* general key count quota */
33 unsigned int key_quota_maxbytes = 20000; /* general key space quota */
34
35 static LIST_HEAD(key_types_list);
36 static DECLARE_RWSEM(key_types_sem);
37
38 static void key_cleanup(struct work_struct *work);
39 static DECLARE_WORK(key_cleanup_task, key_cleanup);
40
41 /* we serialise key instantiation and link */
42 DEFINE_MUTEX(key_construction_mutex);
43
44 /* any key who's type gets unegistered will be re-typed to this */
45 static struct key_type key_type_dead = {
46 .name = "dead",
47 };
48
49 #ifdef KEY_DEBUGGING
__key_check(const struct key * key)50 void __key_check(const struct key *key)
51 {
52 printk("__key_check: key %p {%08x} should be {%08x}\n",
53 key, key->magic, KEY_DEBUG_MAGIC);
54 BUG();
55 }
56 #endif
57
58 /*****************************************************************************/
59 /*
60 * get the key quota record for a user, allocating a new record if one doesn't
61 * already exist
62 */
key_user_lookup(uid_t uid)63 struct key_user *key_user_lookup(uid_t uid)
64 {
65 struct key_user *candidate = NULL, *user;
66 struct rb_node *parent = NULL;
67 struct rb_node **p;
68
69 try_again:
70 p = &key_user_tree.rb_node;
71 spin_lock(&key_user_lock);
72
73 /* search the tree for a user record with a matching UID */
74 while (*p) {
75 parent = *p;
76 user = rb_entry(parent, struct key_user, node);
77
78 if (uid < user->uid)
79 p = &(*p)->rb_left;
80 else if (uid > user->uid)
81 p = &(*p)->rb_right;
82 else
83 goto found;
84 }
85
86 /* if we get here, we failed to find a match in the tree */
87 if (!candidate) {
88 /* allocate a candidate user record if we don't already have
89 * one */
90 spin_unlock(&key_user_lock);
91
92 user = NULL;
93 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
94 if (unlikely(!candidate))
95 goto out;
96
97 /* the allocation may have scheduled, so we need to repeat the
98 * search lest someone else added the record whilst we were
99 * asleep */
100 goto try_again;
101 }
102
103 /* if we get here, then the user record still hadn't appeared on the
104 * second pass - so we use the candidate record */
105 atomic_set(&candidate->usage, 1);
106 atomic_set(&candidate->nkeys, 0);
107 atomic_set(&candidate->nikeys, 0);
108 candidate->uid = uid;
109 candidate->qnkeys = 0;
110 candidate->qnbytes = 0;
111 spin_lock_init(&candidate->lock);
112 mutex_init(&candidate->cons_lock);
113
114 rb_link_node(&candidate->node, parent, p);
115 rb_insert_color(&candidate->node, &key_user_tree);
116 spin_unlock(&key_user_lock);
117 user = candidate;
118 goto out;
119
120 /* okay - we found a user record for this UID */
121 found:
122 atomic_inc(&user->usage);
123 spin_unlock(&key_user_lock);
124 kfree(candidate);
125 out:
126 return user;
127
128 } /* end key_user_lookup() */
129
130 /*****************************************************************************/
131 /*
132 * dispose of a user structure
133 */
key_user_put(struct key_user * user)134 void key_user_put(struct key_user *user)
135 {
136 if (atomic_dec_and_lock(&user->usage, &key_user_lock)) {
137 rb_erase(&user->node, &key_user_tree);
138 spin_unlock(&key_user_lock);
139
140 kfree(user);
141 }
142
143 } /* end key_user_put() */
144
145 /*****************************************************************************/
146 /*
147 * assign a key the next unique serial number
148 * - these are assigned randomly to avoid security issues through covert
149 * channel problems
150 */
key_alloc_serial(struct key * key)151 static inline void key_alloc_serial(struct key *key)
152 {
153 struct rb_node *parent, **p;
154 struct key *xkey;
155
156 /* propose a random serial number and look for a hole for it in the
157 * serial number tree */
158 do {
159 get_random_bytes(&key->serial, sizeof(key->serial));
160
161 key->serial >>= 1; /* negative numbers are not permitted */
162 } while (key->serial < 3);
163
164 spin_lock(&key_serial_lock);
165
166 attempt_insertion:
167 parent = NULL;
168 p = &key_serial_tree.rb_node;
169
170 while (*p) {
171 parent = *p;
172 xkey = rb_entry(parent, struct key, serial_node);
173
174 if (key->serial < xkey->serial)
175 p = &(*p)->rb_left;
176 else if (key->serial > xkey->serial)
177 p = &(*p)->rb_right;
178 else
179 goto serial_exists;
180 }
181
182 /* we've found a suitable hole - arrange for this key to occupy it */
183 rb_link_node(&key->serial_node, parent, p);
184 rb_insert_color(&key->serial_node, &key_serial_tree);
185
186 spin_unlock(&key_serial_lock);
187 return;
188
189 /* we found a key with the proposed serial number - walk the tree from
190 * that point looking for the next unused serial number */
191 serial_exists:
192 for (;;) {
193 key->serial++;
194 if (key->serial < 3) {
195 key->serial = 3;
196 goto attempt_insertion;
197 }
198
199 parent = rb_next(parent);
200 if (!parent)
201 goto attempt_insertion;
202
203 xkey = rb_entry(parent, struct key, serial_node);
204 if (key->serial < xkey->serial)
205 goto attempt_insertion;
206 }
207
208 } /* end key_alloc_serial() */
209
210 /*****************************************************************************/
211 /*
212 * allocate a key of the specified type
213 * - update the user's quota to reflect the existence of the key
214 * - called from a key-type operation with key_types_sem read-locked by
215 * key_create_or_update()
216 * - this prevents unregistration of the key type
217 * - upon return the key is as yet uninstantiated; the caller needs to either
218 * instantiate the key or discard it before returning
219 */
key_alloc(struct key_type * type,const char * desc,uid_t uid,gid_t gid,const struct cred * cred,key_perm_t perm,unsigned long flags)220 struct key *key_alloc(struct key_type *type, const char *desc,
221 uid_t uid, gid_t gid, const struct cred *cred,
222 key_perm_t perm, unsigned long flags)
223 {
224 struct key_user *user = NULL;
225 struct key *key;
226 size_t desclen, quotalen;
227 int ret;
228
229 key = ERR_PTR(-EINVAL);
230 if (!desc || !*desc)
231 goto error;
232
233 desclen = strlen(desc) + 1;
234 quotalen = desclen + type->def_datalen;
235
236 /* get hold of the key tracking for this user */
237 user = key_user_lookup(uid);
238 if (!user)
239 goto no_memory_1;
240
241 /* check that the user's quota permits allocation of another key and
242 * its description */
243 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
244 unsigned maxkeys = (uid == 0) ?
245 key_quota_root_maxkeys : key_quota_maxkeys;
246 unsigned maxbytes = (uid == 0) ?
247 key_quota_root_maxbytes : key_quota_maxbytes;
248
249 spin_lock(&user->lock);
250 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
251 if (user->qnkeys + 1 >= maxkeys ||
252 user->qnbytes + quotalen >= maxbytes ||
253 user->qnbytes + quotalen < user->qnbytes)
254 goto no_quota;
255 }
256
257 user->qnkeys++;
258 user->qnbytes += quotalen;
259 spin_unlock(&user->lock);
260 }
261
262 /* allocate and initialise the key and its description */
263 key = kmem_cache_alloc(key_jar, GFP_KERNEL);
264 if (!key)
265 goto no_memory_2;
266
267 if (desc) {
268 key->description = kmemdup(desc, desclen, GFP_KERNEL);
269 if (!key->description)
270 goto no_memory_3;
271 }
272
273 atomic_set(&key->usage, 1);
274 init_rwsem(&key->sem);
275 key->type = type;
276 key->user = user;
277 key->quotalen = quotalen;
278 key->datalen = type->def_datalen;
279 key->uid = uid;
280 key->gid = gid;
281 key->perm = perm;
282 key->flags = 0;
283 key->expiry = 0;
284 key->payload.data = NULL;
285 key->security = NULL;
286
287 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
288 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
289
290 memset(&key->type_data, 0, sizeof(key->type_data));
291
292 #ifdef KEY_DEBUGGING
293 key->magic = KEY_DEBUG_MAGIC;
294 #endif
295
296 /* let the security module know about the key */
297 ret = security_key_alloc(key, cred, flags);
298 if (ret < 0)
299 goto security_error;
300
301 /* publish the key by giving it a serial number */
302 atomic_inc(&user->nkeys);
303 key_alloc_serial(key);
304
305 error:
306 return key;
307
308 security_error:
309 kfree(key->description);
310 kmem_cache_free(key_jar, key);
311 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
312 spin_lock(&user->lock);
313 user->qnkeys--;
314 user->qnbytes -= quotalen;
315 spin_unlock(&user->lock);
316 }
317 key_user_put(user);
318 key = ERR_PTR(ret);
319 goto error;
320
321 no_memory_3:
322 kmem_cache_free(key_jar, key);
323 no_memory_2:
324 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
325 spin_lock(&user->lock);
326 user->qnkeys--;
327 user->qnbytes -= quotalen;
328 spin_unlock(&user->lock);
329 }
330 key_user_put(user);
331 no_memory_1:
332 key = ERR_PTR(-ENOMEM);
333 goto error;
334
335 no_quota:
336 spin_unlock(&user->lock);
337 key_user_put(user);
338 key = ERR_PTR(-EDQUOT);
339 goto error;
340
341 } /* end key_alloc() */
342
343 EXPORT_SYMBOL(key_alloc);
344
345 /*****************************************************************************/
346 /*
347 * reserve an amount of quota for the key's payload
348 */
key_payload_reserve(struct key * key,size_t datalen)349 int key_payload_reserve(struct key *key, size_t datalen)
350 {
351 int delta = (int) datalen - key->datalen;
352 int ret = 0;
353
354 key_check(key);
355
356 /* contemplate the quota adjustment */
357 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
358 unsigned maxbytes = (key->user->uid == 0) ?
359 key_quota_root_maxbytes : key_quota_maxbytes;
360
361 spin_lock(&key->user->lock);
362
363 if (delta > 0 &&
364 (key->user->qnbytes + delta >= maxbytes ||
365 key->user->qnbytes + delta < key->user->qnbytes)) {
366 ret = -EDQUOT;
367 }
368 else {
369 key->user->qnbytes += delta;
370 key->quotalen += delta;
371 }
372 spin_unlock(&key->user->lock);
373 }
374
375 /* change the recorded data length if that didn't generate an error */
376 if (ret == 0)
377 key->datalen = datalen;
378
379 return ret;
380
381 } /* end key_payload_reserve() */
382
383 EXPORT_SYMBOL(key_payload_reserve);
384
385 /*****************************************************************************/
386 /*
387 * instantiate a key and link it into the target keyring atomically
388 * - called with the target keyring's semaphore writelocked
389 */
__key_instantiate_and_link(struct key * key,const void * data,size_t datalen,struct key * keyring,struct key * authkey)390 static int __key_instantiate_and_link(struct key *key,
391 const void *data,
392 size_t datalen,
393 struct key *keyring,
394 struct key *authkey)
395 {
396 int ret, awaken;
397
398 key_check(key);
399 key_check(keyring);
400
401 awaken = 0;
402 ret = -EBUSY;
403
404 mutex_lock(&key_construction_mutex);
405
406 /* can't instantiate twice */
407 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
408 /* instantiate the key */
409 ret = key->type->instantiate(key, data, datalen);
410
411 if (ret == 0) {
412 /* mark the key as being instantiated */
413 atomic_inc(&key->user->nikeys);
414 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
415
416 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
417 awaken = 1;
418
419 /* and link it into the destination keyring */
420 if (keyring)
421 ret = __key_link(keyring, key);
422
423 /* disable the authorisation key */
424 if (authkey)
425 key_revoke(authkey);
426 }
427 }
428
429 mutex_unlock(&key_construction_mutex);
430
431 /* wake up anyone waiting for a key to be constructed */
432 if (awaken)
433 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
434
435 return ret;
436
437 } /* end __key_instantiate_and_link() */
438
439 /*****************************************************************************/
440 /*
441 * instantiate a key and link it into the target keyring atomically
442 */
key_instantiate_and_link(struct key * key,const void * data,size_t datalen,struct key * keyring,struct key * authkey)443 int key_instantiate_and_link(struct key *key,
444 const void *data,
445 size_t datalen,
446 struct key *keyring,
447 struct key *authkey)
448 {
449 int ret;
450
451 if (keyring)
452 down_write(&keyring->sem);
453
454 ret = __key_instantiate_and_link(key, data, datalen, keyring, authkey);
455
456 if (keyring)
457 up_write(&keyring->sem);
458
459 return ret;
460
461 } /* end key_instantiate_and_link() */
462
463 EXPORT_SYMBOL(key_instantiate_and_link);
464
465 /*****************************************************************************/
466 /*
467 * negatively instantiate a key and link it into the target keyring atomically
468 */
key_negate_and_link(struct key * key,unsigned timeout,struct key * keyring,struct key * authkey)469 int key_negate_and_link(struct key *key,
470 unsigned timeout,
471 struct key *keyring,
472 struct key *authkey)
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 mutex_lock(&key_construction_mutex);
487
488 /* can't instantiate twice */
489 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
490 /* mark the key as being negatively instantiated */
491 atomic_inc(&key->user->nikeys);
492 set_bit(KEY_FLAG_NEGATIVE, &key->flags);
493 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
494 now = current_kernel_time();
495 key->expiry = now.tv_sec + timeout;
496
497 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
498 awaken = 1;
499
500 ret = 0;
501
502 /* and link it into the destination keyring */
503 if (keyring)
504 ret = __key_link(keyring, key);
505
506 /* disable the authorisation key */
507 if (authkey)
508 key_revoke(authkey);
509 }
510
511 mutex_unlock(&key_construction_mutex);
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_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
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 */
key_cleanup(struct work_struct * work)531 static void key_cleanup(struct work_struct *work)
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 key_check(key);
557
558 security_key_free(key);
559
560 /* deal with the user's key tracking and quota */
561 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
562 spin_lock(&key->user->lock);
563 key->user->qnkeys--;
564 key->user->qnbytes -= key->quotalen;
565 spin_unlock(&key->user->lock);
566 }
567
568 atomic_dec(&key->user->nkeys);
569 if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
570 atomic_dec(&key->user->nikeys);
571
572 key_user_put(key->user);
573
574 /* now throw away the key memory */
575 if (key->type->destroy)
576 key->type->destroy(key);
577
578 kfree(key->description);
579
580 #ifdef KEY_DEBUGGING
581 key->magic = KEY_DEBUG_MAGIC_X;
582 #endif
583 kmem_cache_free(key_jar, key);
584
585 /* there may, of course, be more than one key to destroy */
586 goto go_again;
587
588 } /* end key_cleanup() */
589
590 /*****************************************************************************/
591 /*
592 * dispose of a reference to a key
593 * - when all the references are gone, we schedule the cleanup task to come and
594 * pull it out of the tree in definite process context
595 */
key_put(struct key * key)596 void key_put(struct key *key)
597 {
598 if (key) {
599 key_check(key);
600
601 if (atomic_dec_and_test(&key->usage))
602 schedule_work(&key_cleanup_task);
603 }
604
605 } /* end key_put() */
606
607 EXPORT_SYMBOL(key_put);
608
609 /*****************************************************************************/
610 /*
611 * find a key by its serial number
612 */
key_lookup(key_serial_t id)613 struct key *key_lookup(key_serial_t id)
614 {
615 struct rb_node *n;
616 struct key *key;
617
618 spin_lock(&key_serial_lock);
619
620 /* search the tree for the specified key */
621 n = key_serial_tree.rb_node;
622 while (n) {
623 key = rb_entry(n, struct key, serial_node);
624
625 if (id < key->serial)
626 n = n->rb_left;
627 else if (id > key->serial)
628 n = n->rb_right;
629 else
630 goto found;
631 }
632
633 not_found:
634 key = ERR_PTR(-ENOKEY);
635 goto error;
636
637 found:
638 /* pretend it doesn't exist if it's dead */
639 if (atomic_read(&key->usage) == 0 ||
640 test_bit(KEY_FLAG_DEAD, &key->flags) ||
641 key->type == &key_type_dead)
642 goto not_found;
643
644 /* this races with key_put(), but that doesn't matter since key_put()
645 * doesn't actually change the key
646 */
647 atomic_inc(&key->usage);
648
649 error:
650 spin_unlock(&key_serial_lock);
651 return key;
652
653 } /* end key_lookup() */
654
655 /*****************************************************************************/
656 /*
657 * find and lock the specified key type against removal
658 * - we return with the sem readlocked
659 */
key_type_lookup(const char * type)660 struct key_type *key_type_lookup(const char *type)
661 {
662 struct key_type *ktype;
663
664 down_read(&key_types_sem);
665
666 /* look up the key type to see if it's one of the registered kernel
667 * types */
668 list_for_each_entry(ktype, &key_types_list, link) {
669 if (strcmp(ktype->name, type) == 0)
670 goto found_kernel_type;
671 }
672
673 up_read(&key_types_sem);
674 ktype = ERR_PTR(-ENOKEY);
675
676 found_kernel_type:
677 return ktype;
678
679 } /* end key_type_lookup() */
680
681 /*****************************************************************************/
682 /*
683 * unlock a key type
684 */
key_type_put(struct key_type * ktype)685 void key_type_put(struct key_type *ktype)
686 {
687 up_read(&key_types_sem);
688
689 } /* end key_type_put() */
690
691 /*****************************************************************************/
692 /*
693 * attempt to update an existing key
694 * - the key has an incremented refcount
695 * - we need to put the key if we get an error
696 */
__key_update(key_ref_t key_ref,const void * payload,size_t plen)697 static inline key_ref_t __key_update(key_ref_t key_ref,
698 const void *payload, size_t plen)
699 {
700 struct key *key = key_ref_to_ptr(key_ref);
701 int ret;
702
703 /* need write permission on the key to update it */
704 ret = key_permission(key_ref, KEY_WRITE);
705 if (ret < 0)
706 goto error;
707
708 ret = -EEXIST;
709 if (!key->type->update)
710 goto error;
711
712 down_write(&key->sem);
713
714 ret = key->type->update(key, payload, plen);
715 if (ret == 0)
716 /* updating a negative key instantiates it */
717 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
718
719 up_write(&key->sem);
720
721 if (ret < 0)
722 goto error;
723 out:
724 return key_ref;
725
726 error:
727 key_put(key);
728 key_ref = ERR_PTR(ret);
729 goto out;
730
731 } /* end __key_update() */
732
733 /*****************************************************************************/
734 /*
735 * search the specified keyring for a key of the same description; if one is
736 * found, update it, otherwise add a new one
737 */
key_create_or_update(key_ref_t keyring_ref,const char * type,const char * description,const void * payload,size_t plen,key_perm_t perm,unsigned long flags)738 key_ref_t key_create_or_update(key_ref_t keyring_ref,
739 const char *type,
740 const char *description,
741 const void *payload,
742 size_t plen,
743 key_perm_t perm,
744 unsigned long flags)
745 {
746 const struct cred *cred = current_cred();
747 struct key_type *ktype;
748 struct key *keyring, *key = NULL;
749 key_ref_t key_ref;
750 int ret;
751
752 /* look up the key type to see if it's one of the registered kernel
753 * types */
754 ktype = key_type_lookup(type);
755 if (IS_ERR(ktype)) {
756 key_ref = ERR_PTR(-ENODEV);
757 goto error;
758 }
759
760 key_ref = ERR_PTR(-EINVAL);
761 if (!ktype->match || !ktype->instantiate)
762 goto error_2;
763
764 keyring = key_ref_to_ptr(keyring_ref);
765
766 key_check(keyring);
767
768 key_ref = ERR_PTR(-ENOTDIR);
769 if (keyring->type != &key_type_keyring)
770 goto error_2;
771
772 down_write(&keyring->sem);
773
774 /* if we're going to allocate a new key, we're going to have
775 * to modify the keyring */
776 ret = key_permission(keyring_ref, KEY_WRITE);
777 if (ret < 0) {
778 key_ref = ERR_PTR(ret);
779 goto error_3;
780 }
781
782 /* if it's possible to update this type of key, search for an existing
783 * key of the same type and description in the destination keyring and
784 * update that instead if possible
785 */
786 if (ktype->update) {
787 key_ref = __keyring_search_one(keyring_ref, ktype, description,
788 0);
789 if (!IS_ERR(key_ref))
790 goto found_matching_key;
791 }
792
793 /* if the client doesn't provide, decide on the permissions we want */
794 if (perm == KEY_PERM_UNDEF) {
795 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
796 perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR;
797
798 if (ktype->read)
799 perm |= KEY_POS_READ | KEY_USR_READ;
800
801 if (ktype == &key_type_keyring || ktype->update)
802 perm |= KEY_USR_WRITE;
803 }
804
805 /* allocate a new key */
806 key = key_alloc(ktype, description, cred->fsuid, cred->fsgid, cred,
807 perm, flags);
808 if (IS_ERR(key)) {
809 key_ref = ERR_CAST(key);
810 goto error_3;
811 }
812
813 /* instantiate it and link it into the target keyring */
814 ret = __key_instantiate_and_link(key, payload, plen, keyring, NULL);
815 if (ret < 0) {
816 key_put(key);
817 key_ref = ERR_PTR(ret);
818 goto error_3;
819 }
820
821 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
822
823 error_3:
824 up_write(&keyring->sem);
825 error_2:
826 key_type_put(ktype);
827 error:
828 return key_ref;
829
830 found_matching_key:
831 /* we found a matching key, so we're going to try to update it
832 * - we can drop the locks first as we have the key pinned
833 */
834 up_write(&keyring->sem);
835 key_type_put(ktype);
836
837 key_ref = __key_update(key_ref, payload, plen);
838 goto error;
839
840 } /* end key_create_or_update() */
841
842 EXPORT_SYMBOL(key_create_or_update);
843
844 /*****************************************************************************/
845 /*
846 * update a key
847 */
key_update(key_ref_t key_ref,const void * payload,size_t plen)848 int key_update(key_ref_t key_ref, const void *payload, size_t plen)
849 {
850 struct key *key = key_ref_to_ptr(key_ref);
851 int ret;
852
853 key_check(key);
854
855 /* the key must be writable */
856 ret = key_permission(key_ref, KEY_WRITE);
857 if (ret < 0)
858 goto error;
859
860 /* attempt to update it if supported */
861 ret = -EOPNOTSUPP;
862 if (key->type->update) {
863 down_write(&key->sem);
864
865 ret = key->type->update(key, payload, plen);
866 if (ret == 0)
867 /* updating a negative key instantiates it */
868 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
869
870 up_write(&key->sem);
871 }
872
873 error:
874 return ret;
875
876 } /* end key_update() */
877
878 EXPORT_SYMBOL(key_update);
879
880 /*****************************************************************************/
881 /*
882 * revoke a key
883 */
key_revoke(struct key * key)884 void key_revoke(struct key *key)
885 {
886 key_check(key);
887
888 /* make sure no one's trying to change or use the key when we mark it
889 * - we tell lockdep that we might nest because we might be revoking an
890 * authorisation key whilst holding the sem on a key we've just
891 * instantiated
892 */
893 down_write_nested(&key->sem, 1);
894 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
895 key->type->revoke)
896 key->type->revoke(key);
897
898 up_write(&key->sem);
899
900 } /* end key_revoke() */
901
902 EXPORT_SYMBOL(key_revoke);
903
904 /*****************************************************************************/
905 /*
906 * register a type of key
907 */
register_key_type(struct key_type * ktype)908 int register_key_type(struct key_type *ktype)
909 {
910 struct key_type *p;
911 int ret;
912
913 ret = -EEXIST;
914 down_write(&key_types_sem);
915
916 /* disallow key types with the same name */
917 list_for_each_entry(p, &key_types_list, link) {
918 if (strcmp(p->name, ktype->name) == 0)
919 goto out;
920 }
921
922 /* store the type */
923 list_add(&ktype->link, &key_types_list);
924 ret = 0;
925
926 out:
927 up_write(&key_types_sem);
928 return ret;
929
930 } /* end register_key_type() */
931
932 EXPORT_SYMBOL(register_key_type);
933
934 /*****************************************************************************/
935 /*
936 * unregister a type of key
937 */
unregister_key_type(struct key_type * ktype)938 void unregister_key_type(struct key_type *ktype)
939 {
940 struct rb_node *_n;
941 struct key *key;
942
943 down_write(&key_types_sem);
944
945 /* withdraw the key type */
946 list_del_init(&ktype->link);
947
948 /* mark all the keys of this type dead */
949 spin_lock(&key_serial_lock);
950
951 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
952 key = rb_entry(_n, struct key, serial_node);
953
954 if (key->type == ktype)
955 key->type = &key_type_dead;
956 }
957
958 spin_unlock(&key_serial_lock);
959
960 /* make sure everyone revalidates their keys */
961 synchronize_rcu();
962
963 /* we should now be able to destroy the payloads of all the keys of
964 * this type with impunity */
965 spin_lock(&key_serial_lock);
966
967 for (_n = rb_first(&key_serial_tree); _n; _n = rb_next(_n)) {
968 key = rb_entry(_n, struct key, serial_node);
969
970 if (key->type == ktype) {
971 if (ktype->destroy)
972 ktype->destroy(key);
973 memset(&key->payload, KEY_DESTROY, sizeof(key->payload));
974 }
975 }
976
977 spin_unlock(&key_serial_lock);
978 up_write(&key_types_sem);
979
980 } /* end unregister_key_type() */
981
982 EXPORT_SYMBOL(unregister_key_type);
983
984 /*****************************************************************************/
985 /*
986 * initialise the key management stuff
987 */
key_init(void)988 void __init key_init(void)
989 {
990 /* allocate a slab in which we can store keys */
991 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
992 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
993
994 /* add the special key types */
995 list_add_tail(&key_type_keyring.link, &key_types_list);
996 list_add_tail(&key_type_dead.link, &key_types_list);
997 list_add_tail(&key_type_user.link, &key_types_list);
998
999 /* record the root user tracking */
1000 rb_link_node(&root_key_user.node,
1001 NULL,
1002 &key_user_tree.rb_node);
1003
1004 rb_insert_color(&root_key_user.node,
1005 &key_user_tree);
1006
1007 } /* end key_init() */
1008