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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 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 = 1000000; /* root's key count quota */
31 unsigned int key_quota_root_maxbytes = 25000000; /* 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 /* We serialise key instantiation and link */
39 DEFINE_MUTEX(key_construction_mutex);
40
41 #ifdef KEY_DEBUGGING
42 void __key_check(const struct key *key)
43 {
44 printk("__key_check: key %p {%08x} should be {%08x}\n",
45 key, key->magic, KEY_DEBUG_MAGIC);
46 BUG();
47 }
48 #endif
49
50 /*
51 * Get the key quota record for a user, allocating a new record if one doesn't
52 * already exist.
53 */
54 struct key_user *key_user_lookup(kuid_t uid)
55 {
56 struct key_user *candidate = NULL, *user;
57 struct rb_node *parent = NULL;
58 struct rb_node **p;
59
60 try_again:
61 p = &key_user_tree.rb_node;
62 spin_lock(&key_user_lock);
63
64 /* search the tree for a user record with a matching UID */
65 while (*p) {
66 parent = *p;
67 user = rb_entry(parent, struct key_user, node);
68
69 if (uid_lt(uid, user->uid))
70 p = &(*p)->rb_left;
71 else if (uid_gt(uid, user->uid))
72 p = &(*p)->rb_right;
73 else
74 goto found;
75 }
76
77 /* if we get here, we failed to find a match in the tree */
78 if (!candidate) {
79 /* allocate a candidate user record if we don't already have
80 * one */
81 spin_unlock(&key_user_lock);
82
83 user = NULL;
84 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
85 if (unlikely(!candidate))
86 goto out;
87
88 /* the allocation may have scheduled, so we need to repeat the
89 * search lest someone else added the record whilst we were
90 * asleep */
91 goto try_again;
92 }
93
94 /* if we get here, then the user record still hadn't appeared on the
95 * second pass - so we use the candidate record */
96 atomic_set(&candidate->usage, 1);
97 atomic_set(&candidate->nkeys, 0);
98 atomic_set(&candidate->nikeys, 0);
99 candidate->uid = uid;
100 candidate->qnkeys = 0;
101 candidate->qnbytes = 0;
102 spin_lock_init(&candidate->lock);
103 mutex_init(&candidate->cons_lock);
104
105 rb_link_node(&candidate->node, parent, p);
106 rb_insert_color(&candidate->node, &key_user_tree);
107 spin_unlock(&key_user_lock);
108 user = candidate;
109 goto out;
110
111 /* okay - we found a user record for this UID */
112 found:
113 atomic_inc(&user->usage);
114 spin_unlock(&key_user_lock);
115 kfree(candidate);
116 out:
117 return user;
118 }
119
120 /*
121 * Dispose of a user structure
122 */
123 void key_user_put(struct key_user *user)
124 {
125 if (atomic_dec_and_lock(&user->usage, &key_user_lock)) {
126 rb_erase(&user->node, &key_user_tree);
127 spin_unlock(&key_user_lock);
128
129 kfree(user);
130 }
131 }
132
133 /*
134 * Allocate a serial number for a key. These are assigned randomly to avoid
135 * security issues through covert channel problems.
136 */
137 static inline void key_alloc_serial(struct key *key)
138 {
139 struct rb_node *parent, **p;
140 struct key *xkey;
141
142 /* propose a random serial number and look for a hole for it in the
143 * serial number tree */
144 do {
145 get_random_bytes(&key->serial, sizeof(key->serial));
146
147 key->serial >>= 1; /* negative numbers are not permitted */
148 } while (key->serial < 3);
149
150 spin_lock(&key_serial_lock);
151
152 attempt_insertion:
153 parent = NULL;
154 p = &key_serial_tree.rb_node;
155
156 while (*p) {
157 parent = *p;
158 xkey = rb_entry(parent, struct key, serial_node);
159
160 if (key->serial < xkey->serial)
161 p = &(*p)->rb_left;
162 else if (key->serial > xkey->serial)
163 p = &(*p)->rb_right;
164 else
165 goto serial_exists;
166 }
167
168 /* we've found a suitable hole - arrange for this key to occupy it */
169 rb_link_node(&key->serial_node, parent, p);
170 rb_insert_color(&key->serial_node, &key_serial_tree);
171
172 spin_unlock(&key_serial_lock);
173 return;
174
175 /* we found a key with the proposed serial number - walk the tree from
176 * that point looking for the next unused serial number */
177 serial_exists:
178 for (;;) {
179 key->serial++;
180 if (key->serial < 3) {
181 key->serial = 3;
182 goto attempt_insertion;
183 }
184
185 parent = rb_next(parent);
186 if (!parent)
187 goto attempt_insertion;
188
189 xkey = rb_entry(parent, struct key, serial_node);
190 if (key->serial < xkey->serial)
191 goto attempt_insertion;
192 }
193 }
194
195 /**
196 * key_alloc - Allocate a key of the specified type.
197 * @type: The type of key to allocate.
198 * @desc: The key description to allow the key to be searched out.
199 * @uid: The owner of the new key.
200 * @gid: The group ID for the new key's group permissions.
201 * @cred: The credentials specifying UID namespace.
202 * @perm: The permissions mask of the new key.
203 * @flags: Flags specifying quota properties.
204 *
205 * Allocate a key of the specified type with the attributes given. The key is
206 * returned in an uninstantiated state and the caller needs to instantiate the
207 * key before returning.
208 *
209 * The user's key count quota is updated to reflect the creation of the key and
210 * the user's key data quota has the default for the key type reserved. The
211 * instantiation function should amend this as necessary. If insufficient
212 * quota is available, -EDQUOT will be returned.
213 *
214 * The LSM security modules can prevent a key being created, in which case
215 * -EACCES will be returned.
216 *
217 * Returns a pointer to the new key if successful and an error code otherwise.
218 *
219 * Note that the caller needs to ensure the key type isn't uninstantiated.
220 * Internally this can be done by locking key_types_sem. Externally, this can
221 * be done by either never unregistering the key type, or making sure
222 * key_alloc() calls don't race with module unloading.
223 */
224 struct key *key_alloc(struct key_type *type, const char *desc,
225 kuid_t uid, kgid_t gid, const struct cred *cred,
226 key_perm_t perm, unsigned long flags)
227 {
228 struct key_user *user = NULL;
229 struct key *key;
230 size_t desclen, quotalen;
231 int ret;
232
233 key = ERR_PTR(-EINVAL);
234 if (!desc || !*desc)
235 goto error;
236
237 if (type->vet_description) {
238 ret = type->vet_description(desc);
239 if (ret < 0) {
240 key = ERR_PTR(ret);
241 goto error;
242 }
243 }
244
245 desclen = strlen(desc);
246 quotalen = desclen + 1 + type->def_datalen;
247
248 /* get hold of the key tracking for this user */
249 user = key_user_lookup(uid);
250 if (!user)
251 goto no_memory_1;
252
253 /* check that the user's quota permits allocation of another key and
254 * its description */
255 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
256 unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
257 key_quota_root_maxkeys : key_quota_maxkeys;
258 unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
259 key_quota_root_maxbytes : key_quota_maxbytes;
260
261 spin_lock(&user->lock);
262 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
263 if (user->qnkeys + 1 >= maxkeys ||
264 user->qnbytes + quotalen >= maxbytes ||
265 user->qnbytes + quotalen < user->qnbytes)
266 goto no_quota;
267 }
268
269 user->qnkeys++;
270 user->qnbytes += quotalen;
271 spin_unlock(&user->lock);
272 }
273
274 /* allocate and initialise the key and its description */
275 key = kmem_cache_zalloc(key_jar, GFP_KERNEL);
276 if (!key)
277 goto no_memory_2;
278
279 key->index_key.desc_len = desclen;
280 key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
281 if (!key->index_key.description)
282 goto no_memory_3;
283
284 atomic_set(&key->usage, 1);
285 init_rwsem(&key->sem);
286 lockdep_set_class(&key->sem, &type->lock_class);
287 key->index_key.type = type;
288 key->user = user;
289 key->quotalen = quotalen;
290 key->datalen = type->def_datalen;
291 key->uid = uid;
292 key->gid = gid;
293 key->perm = perm;
294
295 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
296 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
297 if (flags & KEY_ALLOC_TRUSTED)
298 key->flags |= 1 << KEY_FLAG_TRUSTED;
299
300 #ifdef KEY_DEBUGGING
301 key->magic = KEY_DEBUG_MAGIC;
302 #endif
303
304 /* let the security module know about the key */
305 ret = security_key_alloc(key, cred, flags);
306 if (ret < 0)
307 goto security_error;
308
309 /* publish the key by giving it a serial number */
310 atomic_inc(&user->nkeys);
311 key_alloc_serial(key);
312
313 error:
314 return key;
315
316 security_error:
317 kfree(key->description);
318 kmem_cache_free(key_jar, key);
319 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
320 spin_lock(&user->lock);
321 user->qnkeys--;
322 user->qnbytes -= quotalen;
323 spin_unlock(&user->lock);
324 }
325 key_user_put(user);
326 key = ERR_PTR(ret);
327 goto error;
328
329 no_memory_3:
330 kmem_cache_free(key_jar, key);
331 no_memory_2:
332 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
333 spin_lock(&user->lock);
334 user->qnkeys--;
335 user->qnbytes -= quotalen;
336 spin_unlock(&user->lock);
337 }
338 key_user_put(user);
339 no_memory_1:
340 key = ERR_PTR(-ENOMEM);
341 goto error;
342
343 no_quota:
344 spin_unlock(&user->lock);
345 key_user_put(user);
346 key = ERR_PTR(-EDQUOT);
347 goto error;
348 }
349 EXPORT_SYMBOL(key_alloc);
350
351 /**
352 * key_payload_reserve - Adjust data quota reservation for the key's payload
353 * @key: The key to make the reservation for.
354 * @datalen: The amount of data payload the caller now wants.
355 *
356 * Adjust the amount of the owning user's key data quota that a key reserves.
357 * If the amount is increased, then -EDQUOT may be returned if there isn't
358 * enough free quota available.
359 *
360 * If successful, 0 is returned.
361 */
362 int key_payload_reserve(struct key *key, size_t datalen)
363 {
364 int delta = (int)datalen - key->datalen;
365 int ret = 0;
366
367 key_check(key);
368
369 /* contemplate the quota adjustment */
370 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
371 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
372 key_quota_root_maxbytes : key_quota_maxbytes;
373
374 spin_lock(&key->user->lock);
375
376 if (delta > 0 &&
377 (key->user->qnbytes + delta >= maxbytes ||
378 key->user->qnbytes + delta < key->user->qnbytes)) {
379 ret = -EDQUOT;
380 }
381 else {
382 key->user->qnbytes += delta;
383 key->quotalen += delta;
384 }
385 spin_unlock(&key->user->lock);
386 }
387
388 /* change the recorded data length if that didn't generate an error */
389 if (ret == 0)
390 key->datalen = datalen;
391
392 return ret;
393 }
394 EXPORT_SYMBOL(key_payload_reserve);
395
396 /*
397 * Instantiate a key and link it into the target keyring atomically. Must be
398 * called with the target keyring's semaphore writelocked. The target key's
399 * semaphore need not be locked as instantiation is serialised by
400 * key_construction_mutex.
401 */
402 static int __key_instantiate_and_link(struct key *key,
403 struct key_preparsed_payload *prep,
404 struct key *keyring,
405 struct key *authkey,
406 struct assoc_array_edit **_edit)
407 {
408 int ret, awaken;
409
410 key_check(key);
411 key_check(keyring);
412
413 awaken = 0;
414 ret = -EBUSY;
415
416 mutex_lock(&key_construction_mutex);
417
418 /* can't instantiate twice */
419 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
420 /* instantiate the key */
421 ret = key->type->instantiate(key, prep);
422
423 if (ret == 0) {
424 /* mark the key as being instantiated */
425 atomic_inc(&key->user->nikeys);
426 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
427
428 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
429 awaken = 1;
430
431 /* and link it into the destination keyring */
432 if (keyring) {
433 if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
434 set_bit(KEY_FLAG_KEEP, &key->flags);
435
436 __key_link(key, _edit);
437 }
438
439 /* disable the authorisation key */
440 if (authkey)
441 key_revoke(authkey);
442
443 if (prep->expiry != TIME_T_MAX) {
444 key->expiry = prep->expiry;
445 key_schedule_gc(prep->expiry + key_gc_delay);
446 }
447 }
448 }
449
450 mutex_unlock(&key_construction_mutex);
451
452 /* wake up anyone waiting for a key to be constructed */
453 if (awaken)
454 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
455
456 return ret;
457 }
458
459 /**
460 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
461 * @key: The key to instantiate.
462 * @data: The data to use to instantiate the keyring.
463 * @datalen: The length of @data.
464 * @keyring: Keyring to create a link in on success (or NULL).
465 * @authkey: The authorisation token permitting instantiation.
466 *
467 * Instantiate a key that's in the uninstantiated state using the provided data
468 * and, if successful, link it in to the destination keyring if one is
469 * supplied.
470 *
471 * If successful, 0 is returned, the authorisation token is revoked and anyone
472 * waiting for the key is woken up. If the key was already instantiated,
473 * -EBUSY will be returned.
474 */
475 int key_instantiate_and_link(struct key *key,
476 const void *data,
477 size_t datalen,
478 struct key *keyring,
479 struct key *authkey)
480 {
481 struct key_preparsed_payload prep;
482 struct assoc_array_edit *edit;
483 int ret;
484
485 memset(&prep, 0, sizeof(prep));
486 prep.data = data;
487 prep.datalen = datalen;
488 prep.quotalen = key->type->def_datalen;
489 prep.expiry = TIME_T_MAX;
490 if (key->type->preparse) {
491 ret = key->type->preparse(&prep);
492 if (ret < 0)
493 goto error;
494 }
495
496 if (keyring) {
497 ret = __key_link_begin(keyring, &key->index_key, &edit);
498 if (ret < 0)
499 goto error;
500 }
501
502 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
503
504 if (keyring)
505 __key_link_end(keyring, &key->index_key, edit);
506
507 error:
508 if (key->type->preparse)
509 key->type->free_preparse(&prep);
510 return ret;
511 }
512
513 EXPORT_SYMBOL(key_instantiate_and_link);
514
515 /**
516 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
517 * @key: The key to instantiate.
518 * @timeout: The timeout on the negative key.
519 * @error: The error to return when the key is hit.
520 * @keyring: Keyring to create a link in on success (or NULL).
521 * @authkey: The authorisation token permitting instantiation.
522 *
523 * Negatively instantiate a key that's in the uninstantiated state and, if
524 * successful, set its timeout and stored error and link it in to the
525 * destination keyring if one is supplied. The key and any links to the key
526 * will be automatically garbage collected after the timeout expires.
527 *
528 * Negative keys are used to rate limit repeated request_key() calls by causing
529 * them to return the stored error code (typically ENOKEY) until the negative
530 * key expires.
531 *
532 * If successful, 0 is returned, the authorisation token is revoked and anyone
533 * waiting for the key is woken up. If the key was already instantiated,
534 * -EBUSY will be returned.
535 */
536 int key_reject_and_link(struct key *key,
537 unsigned timeout,
538 unsigned error,
539 struct key *keyring,
540 struct key *authkey)
541 {
542 struct assoc_array_edit *edit;
543 struct timespec now;
544 int ret, awaken, link_ret = 0;
545
546 key_check(key);
547 key_check(keyring);
548
549 awaken = 0;
550 ret = -EBUSY;
551
552 if (keyring)
553 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
554
555 mutex_lock(&key_construction_mutex);
556
557 /* can't instantiate twice */
558 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
559 /* mark the key as being negatively instantiated */
560 atomic_inc(&key->user->nikeys);
561 key->reject_error = -error;
562 smp_wmb();
563 set_bit(KEY_FLAG_NEGATIVE, &key->flags);
564 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
565 now = current_kernel_time();
566 key->expiry = now.tv_sec + timeout;
567 key_schedule_gc(key->expiry + key_gc_delay);
568
569 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
570 awaken = 1;
571
572 ret = 0;
573
574 /* and link it into the destination keyring */
575 if (keyring && link_ret == 0)
576 __key_link(key, &edit);
577
578 /* disable the authorisation key */
579 if (authkey)
580 key_revoke(authkey);
581 }
582
583 mutex_unlock(&key_construction_mutex);
584
585 if (keyring)
586 __key_link_end(keyring, &key->index_key, edit);
587
588 /* wake up anyone waiting for a key to be constructed */
589 if (awaken)
590 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
591
592 return ret == 0 ? link_ret : ret;
593 }
594 EXPORT_SYMBOL(key_reject_and_link);
595
596 /**
597 * key_put - Discard a reference to a key.
598 * @key: The key to discard a reference from.
599 *
600 * Discard a reference to a key, and when all the references are gone, we
601 * schedule the cleanup task to come and pull it out of the tree in process
602 * context at some later time.
603 */
604 void key_put(struct key *key)
605 {
606 if (key) {
607 key_check(key);
608
609 if (atomic_dec_and_test(&key->usage))
610 schedule_work(&key_gc_work);
611 }
612 }
613 EXPORT_SYMBOL(key_put);
614
615 /*
616 * Find a key by its serial number.
617 */
618 struct key *key_lookup(key_serial_t id)
619 {
620 struct rb_node *n;
621 struct key *key;
622
623 spin_lock(&key_serial_lock);
624
625 /* search the tree for the specified key */
626 n = key_serial_tree.rb_node;
627 while (n) {
628 key = rb_entry(n, struct key, serial_node);
629
630 if (id < key->serial)
631 n = n->rb_left;
632 else if (id > key->serial)
633 n = n->rb_right;
634 else
635 goto found;
636 }
637
638 not_found:
639 key = ERR_PTR(-ENOKEY);
640 goto error;
641
642 found:
643 /* pretend it doesn't exist if it is awaiting deletion */
644 if (atomic_read(&key->usage) == 0)
645 goto not_found;
646
647 /* this races with key_put(), but that doesn't matter since key_put()
648 * doesn't actually change the key
649 */
650 __key_get(key);
651
652 error:
653 spin_unlock(&key_serial_lock);
654 return key;
655 }
656
657 /*
658 * Find and lock the specified key type against removal.
659 *
660 * We return with the sem read-locked if successful. If the type wasn't
661 * available -ENOKEY is returned instead.
662 */
663 struct key_type *key_type_lookup(const char *type)
664 {
665 struct key_type *ktype;
666
667 down_read(&key_types_sem);
668
669 /* look up the key type to see if it's one of the registered kernel
670 * types */
671 list_for_each_entry(ktype, &key_types_list, link) {
672 if (strcmp(ktype->name, type) == 0)
673 goto found_kernel_type;
674 }
675
676 up_read(&key_types_sem);
677 ktype = ERR_PTR(-ENOKEY);
678
679 found_kernel_type:
680 return ktype;
681 }
682
683 void key_set_timeout(struct key *key, unsigned timeout)
684 {
685 struct timespec now;
686 time_t expiry = 0;
687
688 /* make the changes with the locks held to prevent races */
689 down_write(&key->sem);
690
691 if (timeout > 0) {
692 now = current_kernel_time();
693 expiry = now.tv_sec + timeout;
694 }
695
696 key->expiry = expiry;
697 key_schedule_gc(key->expiry + key_gc_delay);
698
699 up_write(&key->sem);
700 }
701 EXPORT_SYMBOL_GPL(key_set_timeout);
702
703 /*
704 * Unlock a key type locked by key_type_lookup().
705 */
706 void key_type_put(struct key_type *ktype)
707 {
708 up_read(&key_types_sem);
709 }
710
711 /*
712 * Attempt to update an existing key.
713 *
714 * The key is given to us with an incremented refcount that we need to discard
715 * if we get an error.
716 */
717 static inline key_ref_t __key_update(key_ref_t key_ref,
718 struct key_preparsed_payload *prep)
719 {
720 struct key *key = key_ref_to_ptr(key_ref);
721 int ret;
722
723 /* need write permission on the key to update it */
724 ret = key_permission(key_ref, KEY_NEED_WRITE);
725 if (ret < 0)
726 goto error;
727
728 ret = -EEXIST;
729 if (!key->type->update)
730 goto error;
731
732 down_write(&key->sem);
733
734 ret = key->type->update(key, prep);
735 if (ret == 0)
736 /* updating a negative key instantiates it */
737 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
738
739 up_write(&key->sem);
740
741 if (ret < 0)
742 goto error;
743 out:
744 return key_ref;
745
746 error:
747 key_put(key);
748 key_ref = ERR_PTR(ret);
749 goto out;
750 }
751
752 /**
753 * key_create_or_update - Update or create and instantiate a key.
754 * @keyring_ref: A pointer to the destination keyring with possession flag.
755 * @type: The type of key.
756 * @description: The searchable description for the key.
757 * @payload: The data to use to instantiate or update the key.
758 * @plen: The length of @payload.
759 * @perm: The permissions mask for a new key.
760 * @flags: The quota flags for a new key.
761 *
762 * Search the destination keyring for a key of the same description and if one
763 * is found, update it, otherwise create and instantiate a new one and create a
764 * link to it from that keyring.
765 *
766 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
767 * concocted.
768 *
769 * Returns a pointer to the new key if successful, -ENODEV if the key type
770 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
771 * caller isn't permitted to modify the keyring or the LSM did not permit
772 * creation of the key.
773 *
774 * On success, the possession flag from the keyring ref will be tacked on to
775 * the key ref before it is returned.
776 */
777 key_ref_t key_create_or_update(key_ref_t keyring_ref,
778 const char *type,
779 const char *description,
780 const void *payload,
781 size_t plen,
782 key_perm_t perm,
783 unsigned long flags)
784 {
785 struct keyring_index_key index_key = {
786 .description = description,
787 };
788 struct key_preparsed_payload prep;
789 struct assoc_array_edit *edit;
790 const struct cred *cred = current_cred();
791 struct key *keyring, *key = NULL;
792 key_ref_t key_ref;
793 int ret;
794
795 /* look up the key type to see if it's one of the registered kernel
796 * types */
797 index_key.type = key_type_lookup(type);
798 if (IS_ERR(index_key.type)) {
799 key_ref = ERR_PTR(-ENODEV);
800 goto error;
801 }
802
803 key_ref = ERR_PTR(-EINVAL);
804 if (!index_key.type->instantiate ||
805 (!index_key.description && !index_key.type->preparse))
806 goto error_put_type;
807
808 keyring = key_ref_to_ptr(keyring_ref);
809
810 key_check(keyring);
811
812 key_ref = ERR_PTR(-ENOTDIR);
813 if (keyring->type != &key_type_keyring)
814 goto error_put_type;
815
816 memset(&prep, 0, sizeof(prep));
817 prep.data = payload;
818 prep.datalen = plen;
819 prep.quotalen = index_key.type->def_datalen;
820 prep.trusted = flags & KEY_ALLOC_TRUSTED;
821 prep.expiry = TIME_T_MAX;
822 if (index_key.type->preparse) {
823 ret = index_key.type->preparse(&prep);
824 if (ret < 0) {
825 key_ref = ERR_PTR(ret);
826 goto error_free_prep;
827 }
828 if (!index_key.description)
829 index_key.description = prep.description;
830 key_ref = ERR_PTR(-EINVAL);
831 if (!index_key.description)
832 goto error_free_prep;
833 }
834 index_key.desc_len = strlen(index_key.description);
835
836 key_ref = ERR_PTR(-EPERM);
837 if (!prep.trusted && test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags))
838 goto error_free_prep;
839 flags |= prep.trusted ? KEY_ALLOC_TRUSTED : 0;
840
841 ret = __key_link_begin(keyring, &index_key, &edit);
842 if (ret < 0) {
843 key_ref = ERR_PTR(ret);
844 goto error_free_prep;
845 }
846
847 /* if we're going to allocate a new key, we're going to have
848 * to modify the keyring */
849 ret = key_permission(keyring_ref, KEY_NEED_WRITE);
850 if (ret < 0) {
851 key_ref = ERR_PTR(ret);
852 goto error_link_end;
853 }
854
855 /* if it's possible to update this type of key, search for an existing
856 * key of the same type and description in the destination keyring and
857 * update that instead if possible
858 */
859 if (index_key.type->update) {
860 key_ref = find_key_to_update(keyring_ref, &index_key);
861 if (key_ref)
862 goto found_matching_key;
863 }
864
865 /* if the client doesn't provide, decide on the permissions we want */
866 if (perm == KEY_PERM_UNDEF) {
867 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
868 perm |= KEY_USR_VIEW;
869
870 if (index_key.type->read)
871 perm |= KEY_POS_READ;
872
873 if (index_key.type == &key_type_keyring ||
874 index_key.type->update)
875 perm |= KEY_POS_WRITE;
876 }
877
878 /* allocate a new key */
879 key = key_alloc(index_key.type, index_key.description,
880 cred->fsuid, cred->fsgid, cred, perm, flags);
881 if (IS_ERR(key)) {
882 key_ref = ERR_CAST(key);
883 goto error_link_end;
884 }
885
886 /* instantiate it and link it into the target keyring */
887 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
888 if (ret < 0) {
889 key_put(key);
890 key_ref = ERR_PTR(ret);
891 goto error_link_end;
892 }
893
894 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
895
896 error_link_end:
897 __key_link_end(keyring, &index_key, edit);
898 error_free_prep:
899 if (index_key.type->preparse)
900 index_key.type->free_preparse(&prep);
901 error_put_type:
902 key_type_put(index_key.type);
903 error:
904 return key_ref;
905
906 found_matching_key:
907 /* we found a matching key, so we're going to try to update it
908 * - we can drop the locks first as we have the key pinned
909 */
910 __key_link_end(keyring, &index_key, edit);
911
912 key_ref = __key_update(key_ref, &prep);
913 goto error_free_prep;
914 }
915 EXPORT_SYMBOL(key_create_or_update);
916
917 /**
918 * key_update - Update a key's contents.
919 * @key_ref: The pointer (plus possession flag) to the key.
920 * @payload: The data to be used to update the key.
921 * @plen: The length of @payload.
922 *
923 * Attempt to update the contents of a key with the given payload data. The
924 * caller must be granted Write permission on the key. Negative keys can be
925 * instantiated by this method.
926 *
927 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
928 * type does not support updating. The key type may return other errors.
929 */
930 int key_update(key_ref_t key_ref, const void *payload, size_t plen)
931 {
932 struct key_preparsed_payload prep;
933 struct key *key = key_ref_to_ptr(key_ref);
934 int ret;
935
936 key_check(key);
937
938 /* the key must be writable */
939 ret = key_permission(key_ref, KEY_NEED_WRITE);
940 if (ret < 0)
941 goto error;
942
943 /* attempt to update it if supported */
944 ret = -EOPNOTSUPP;
945 if (!key->type->update)
946 goto error;
947
948 memset(&prep, 0, sizeof(prep));
949 prep.data = payload;
950 prep.datalen = plen;
951 prep.quotalen = key->type->def_datalen;
952 prep.expiry = TIME_T_MAX;
953 if (key->type->preparse) {
954 ret = key->type->preparse(&prep);
955 if (ret < 0)
956 goto error;
957 }
958
959 down_write(&key->sem);
960
961 ret = key->type->update(key, &prep);
962 if (ret == 0)
963 /* updating a negative key instantiates it */
964 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
965
966 up_write(&key->sem);
967
968 error:
969 if (key->type->preparse)
970 key->type->free_preparse(&prep);
971 return ret;
972 }
973 EXPORT_SYMBOL(key_update);
974
975 /**
976 * key_revoke - Revoke a key.
977 * @key: The key to be revoked.
978 *
979 * Mark a key as being revoked and ask the type to free up its resources. The
980 * revocation timeout is set and the key and all its links will be
981 * automatically garbage collected after key_gc_delay amount of time if they
982 * are not manually dealt with first.
983 */
984 void key_revoke(struct key *key)
985 {
986 struct timespec now;
987 time_t time;
988
989 key_check(key);
990
991 /* make sure no one's trying to change or use the key when we mark it
992 * - we tell lockdep that we might nest because we might be revoking an
993 * authorisation key whilst holding the sem on a key we've just
994 * instantiated
995 */
996 down_write_nested(&key->sem, 1);
997 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
998 key->type->revoke)
999 key->type->revoke(key);
1000
1001 /* set the death time to no more than the expiry time */
1002 now = current_kernel_time();
1003 time = now.tv_sec;
1004 if (key->revoked_at == 0 || key->revoked_at > time) {
1005 key->revoked_at = time;
1006 key_schedule_gc(key->revoked_at + key_gc_delay);
1007 }
1008
1009 up_write(&key->sem);
1010 }
1011 EXPORT_SYMBOL(key_revoke);
1012
1013 /**
1014 * key_invalidate - Invalidate a key.
1015 * @key: The key to be invalidated.
1016 *
1017 * Mark a key as being invalidated and have it cleaned up immediately. The key
1018 * is ignored by all searches and other operations from this point.
1019 */
1020 void key_invalidate(struct key *key)
1021 {
1022 kenter("%d", key_serial(key));
1023
1024 key_check(key);
1025
1026 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1027 down_write_nested(&key->sem, 1);
1028 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags))
1029 key_schedule_gc_links();
1030 up_write(&key->sem);
1031 }
1032 }
1033 EXPORT_SYMBOL(key_invalidate);
1034
1035 /**
1036 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1037 * @key: The key to be instantiated
1038 * @prep: The preparsed data to load.
1039 *
1040 * Instantiate a key from preparsed data. We assume we can just copy the data
1041 * in directly and clear the old pointers.
1042 *
1043 * This can be pointed to directly by the key type instantiate op pointer.
1044 */
1045 int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1046 {
1047 int ret;
1048
1049 pr_devel("==>%s()\n", __func__);
1050
1051 ret = key_payload_reserve(key, prep->quotalen);
1052 if (ret == 0) {
1053 rcu_assign_keypointer(key, prep->payload.data[0]);
1054 key->payload.data[1] = prep->payload.data[1];
1055 key->payload.data[2] = prep->payload.data[2];
1056 key->payload.data[3] = prep->payload.data[3];
1057 prep->payload.data[0] = NULL;
1058 prep->payload.data[1] = NULL;
1059 prep->payload.data[2] = NULL;
1060 prep->payload.data[3] = NULL;
1061 }
1062 pr_devel("<==%s() = %d\n", __func__, ret);
1063 return ret;
1064 }
1065 EXPORT_SYMBOL(generic_key_instantiate);
1066
1067 /**
1068 * register_key_type - Register a type of key.
1069 * @ktype: The new key type.
1070 *
1071 * Register a new key type.
1072 *
1073 * Returns 0 on success or -EEXIST if a type of this name already exists.
1074 */
1075 int register_key_type(struct key_type *ktype)
1076 {
1077 struct key_type *p;
1078 int ret;
1079
1080 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1081
1082 ret = -EEXIST;
1083 down_write(&key_types_sem);
1084
1085 /* disallow key types with the same name */
1086 list_for_each_entry(p, &key_types_list, link) {
1087 if (strcmp(p->name, ktype->name) == 0)
1088 goto out;
1089 }
1090
1091 /* store the type */
1092 list_add(&ktype->link, &key_types_list);
1093
1094 pr_notice("Key type %s registered\n", ktype->name);
1095 ret = 0;
1096
1097 out:
1098 up_write(&key_types_sem);
1099 return ret;
1100 }
1101 EXPORT_SYMBOL(register_key_type);
1102
1103 /**
1104 * unregister_key_type - Unregister a type of key.
1105 * @ktype: The key type.
1106 *
1107 * Unregister a key type and mark all the extant keys of this type as dead.
1108 * Those keys of this type are then destroyed to get rid of their payloads and
1109 * they and their links will be garbage collected as soon as possible.
1110 */
1111 void unregister_key_type(struct key_type *ktype)
1112 {
1113 down_write(&key_types_sem);
1114 list_del_init(&ktype->link);
1115 downgrade_write(&key_types_sem);
1116 key_gc_keytype(ktype);
1117 pr_notice("Key type %s unregistered\n", ktype->name);
1118 up_read(&key_types_sem);
1119 }
1120 EXPORT_SYMBOL(unregister_key_type);
1121
1122 /*
1123 * Initialise the key management state.
1124 */
1125 void __init key_init(void)
1126 {
1127 /* allocate a slab in which we can store keys */
1128 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1129 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1130
1131 /* add the special key types */
1132 list_add_tail(&key_type_keyring.link, &key_types_list);
1133 list_add_tail(&key_type_dead.link, &key_types_list);
1134 list_add_tail(&key_type_user.link, &key_types_list);
1135 list_add_tail(&key_type_logon.link, &key_types_list);
1136
1137 /* record the root user tracking */
1138 rb_link_node(&root_key_user.node,
1139 NULL,
1140 &key_user_tree.rb_node);
1141
1142 rb_insert_color(&root_key_user.node,
1143 &key_user_tree);
1144 }