]> git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - security/keys/key.c
KEYS: Merge the type-specific data with the payload data
[mirror_ubuntu-bionic-kernel.git] / security / keys / key.c
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 __key_link(key, _edit);
434
435 /* disable the authorisation key */
436 if (authkey)
437 key_revoke(authkey);
438
439 if (prep->expiry != TIME_T_MAX) {
440 key->expiry = prep->expiry;
441 key_schedule_gc(prep->expiry + key_gc_delay);
442 }
443 }
444 }
445
446 mutex_unlock(&key_construction_mutex);
447
448 /* wake up anyone waiting for a key to be constructed */
449 if (awaken)
450 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
451
452 return ret;
453 }
454
455 /**
456 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
457 * @key: The key to instantiate.
458 * @data: The data to use to instantiate the keyring.
459 * @datalen: The length of @data.
460 * @keyring: Keyring to create a link in on success (or NULL).
461 * @authkey: The authorisation token permitting instantiation.
462 *
463 * Instantiate a key that's in the uninstantiated state using the provided data
464 * and, if successful, link it in to the destination keyring if one is
465 * supplied.
466 *
467 * If successful, 0 is returned, the authorisation token is revoked and anyone
468 * waiting for the key is woken up. If the key was already instantiated,
469 * -EBUSY will be returned.
470 */
471 int key_instantiate_and_link(struct key *key,
472 const void *data,
473 size_t datalen,
474 struct key *keyring,
475 struct key *authkey)
476 {
477 struct key_preparsed_payload prep;
478 struct assoc_array_edit *edit;
479 int ret;
480
481 memset(&prep, 0, sizeof(prep));
482 prep.data = data;
483 prep.datalen = datalen;
484 prep.quotalen = key->type->def_datalen;
485 prep.expiry = TIME_T_MAX;
486 if (key->type->preparse) {
487 ret = key->type->preparse(&prep);
488 if (ret < 0)
489 goto error;
490 }
491
492 if (keyring) {
493 ret = __key_link_begin(keyring, &key->index_key, &edit);
494 if (ret < 0)
495 goto error;
496 }
497
498 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
499
500 if (keyring)
501 __key_link_end(keyring, &key->index_key, edit);
502
503 error:
504 if (key->type->preparse)
505 key->type->free_preparse(&prep);
506 return ret;
507 }
508
509 EXPORT_SYMBOL(key_instantiate_and_link);
510
511 /**
512 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
513 * @key: The key to instantiate.
514 * @timeout: The timeout on the negative key.
515 * @error: The error to return when the key is hit.
516 * @keyring: Keyring to create a link in on success (or NULL).
517 * @authkey: The authorisation token permitting instantiation.
518 *
519 * Negatively instantiate a key that's in the uninstantiated state and, if
520 * successful, set its timeout and stored error and link it in to the
521 * destination keyring if one is supplied. The key and any links to the key
522 * will be automatically garbage collected after the timeout expires.
523 *
524 * Negative keys are used to rate limit repeated request_key() calls by causing
525 * them to return the stored error code (typically ENOKEY) until the negative
526 * key expires.
527 *
528 * If successful, 0 is returned, the authorisation token is revoked and anyone
529 * waiting for the key is woken up. If the key was already instantiated,
530 * -EBUSY will be returned.
531 */
532 int key_reject_and_link(struct key *key,
533 unsigned timeout,
534 unsigned error,
535 struct key *keyring,
536 struct key *authkey)
537 {
538 struct assoc_array_edit *edit;
539 struct timespec now;
540 int ret, awaken, link_ret = 0;
541
542 key_check(key);
543 key_check(keyring);
544
545 awaken = 0;
546 ret = -EBUSY;
547
548 if (keyring)
549 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
550
551 mutex_lock(&key_construction_mutex);
552
553 /* can't instantiate twice */
554 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
555 /* mark the key as being negatively instantiated */
556 atomic_inc(&key->user->nikeys);
557 key->reject_error = -error;
558 smp_wmb();
559 set_bit(KEY_FLAG_NEGATIVE, &key->flags);
560 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
561 now = current_kernel_time();
562 key->expiry = now.tv_sec + timeout;
563 key_schedule_gc(key->expiry + key_gc_delay);
564
565 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
566 awaken = 1;
567
568 ret = 0;
569
570 /* and link it into the destination keyring */
571 if (keyring && link_ret == 0)
572 __key_link(key, &edit);
573
574 /* disable the authorisation key */
575 if (authkey)
576 key_revoke(authkey);
577 }
578
579 mutex_unlock(&key_construction_mutex);
580
581 if (keyring)
582 __key_link_end(keyring, &key->index_key, edit);
583
584 /* wake up anyone waiting for a key to be constructed */
585 if (awaken)
586 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
587
588 return ret == 0 ? link_ret : ret;
589 }
590 EXPORT_SYMBOL(key_reject_and_link);
591
592 /**
593 * key_put - Discard a reference to a key.
594 * @key: The key to discard a reference from.
595 *
596 * Discard a reference to a key, and when all the references are gone, we
597 * schedule the cleanup task to come and pull it out of the tree in process
598 * context at some later time.
599 */
600 void key_put(struct key *key)
601 {
602 if (key) {
603 key_check(key);
604
605 if (atomic_dec_and_test(&key->usage))
606 schedule_work(&key_gc_work);
607 }
608 }
609 EXPORT_SYMBOL(key_put);
610
611 /*
612 * Find a key by its serial number.
613 */
614 struct key *key_lookup(key_serial_t id)
615 {
616 struct rb_node *n;
617 struct key *key;
618
619 spin_lock(&key_serial_lock);
620
621 /* search the tree for the specified key */
622 n = key_serial_tree.rb_node;
623 while (n) {
624 key = rb_entry(n, struct key, serial_node);
625
626 if (id < key->serial)
627 n = n->rb_left;
628 else if (id > key->serial)
629 n = n->rb_right;
630 else
631 goto found;
632 }
633
634 not_found:
635 key = ERR_PTR(-ENOKEY);
636 goto error;
637
638 found:
639 /* pretend it doesn't exist if it is awaiting deletion */
640 if (atomic_read(&key->usage) == 0)
641 goto not_found;
642
643 /* this races with key_put(), but that doesn't matter since key_put()
644 * doesn't actually change the key
645 */
646 __key_get(key);
647
648 error:
649 spin_unlock(&key_serial_lock);
650 return key;
651 }
652
653 /*
654 * Find and lock the specified key type against removal.
655 *
656 * We return with the sem read-locked if successful. If the type wasn't
657 * available -ENOKEY is returned instead.
658 */
659 struct key_type *key_type_lookup(const char *type)
660 {
661 struct key_type *ktype;
662
663 down_read(&key_types_sem);
664
665 /* look up the key type to see if it's one of the registered kernel
666 * types */
667 list_for_each_entry(ktype, &key_types_list, link) {
668 if (strcmp(ktype->name, type) == 0)
669 goto found_kernel_type;
670 }
671
672 up_read(&key_types_sem);
673 ktype = ERR_PTR(-ENOKEY);
674
675 found_kernel_type:
676 return ktype;
677 }
678
679 void key_set_timeout(struct key *key, unsigned timeout)
680 {
681 struct timespec now;
682 time_t expiry = 0;
683
684 /* make the changes with the locks held to prevent races */
685 down_write(&key->sem);
686
687 if (timeout > 0) {
688 now = current_kernel_time();
689 expiry = now.tv_sec + timeout;
690 }
691
692 key->expiry = expiry;
693 key_schedule_gc(key->expiry + key_gc_delay);
694
695 up_write(&key->sem);
696 }
697 EXPORT_SYMBOL_GPL(key_set_timeout);
698
699 /*
700 * Unlock a key type locked by key_type_lookup().
701 */
702 void key_type_put(struct key_type *ktype)
703 {
704 up_read(&key_types_sem);
705 }
706
707 /*
708 * Attempt to update an existing key.
709 *
710 * The key is given to us with an incremented refcount that we need to discard
711 * if we get an error.
712 */
713 static inline key_ref_t __key_update(key_ref_t key_ref,
714 struct key_preparsed_payload *prep)
715 {
716 struct key *key = key_ref_to_ptr(key_ref);
717 int ret;
718
719 /* need write permission on the key to update it */
720 ret = key_permission(key_ref, KEY_NEED_WRITE);
721 if (ret < 0)
722 goto error;
723
724 ret = -EEXIST;
725 if (!key->type->update)
726 goto error;
727
728 down_write(&key->sem);
729
730 ret = key->type->update(key, prep);
731 if (ret == 0)
732 /* updating a negative key instantiates it */
733 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
734
735 up_write(&key->sem);
736
737 if (ret < 0)
738 goto error;
739 out:
740 return key_ref;
741
742 error:
743 key_put(key);
744 key_ref = ERR_PTR(ret);
745 goto out;
746 }
747
748 /**
749 * key_create_or_update - Update or create and instantiate a key.
750 * @keyring_ref: A pointer to the destination keyring with possession flag.
751 * @type: The type of key.
752 * @description: The searchable description for the key.
753 * @payload: The data to use to instantiate or update the key.
754 * @plen: The length of @payload.
755 * @perm: The permissions mask for a new key.
756 * @flags: The quota flags for a new key.
757 *
758 * Search the destination keyring for a key of the same description and if one
759 * is found, update it, otherwise create and instantiate a new one and create a
760 * link to it from that keyring.
761 *
762 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
763 * concocted.
764 *
765 * Returns a pointer to the new key if successful, -ENODEV if the key type
766 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
767 * caller isn't permitted to modify the keyring or the LSM did not permit
768 * creation of the key.
769 *
770 * On success, the possession flag from the keyring ref will be tacked on to
771 * the key ref before it is returned.
772 */
773 key_ref_t key_create_or_update(key_ref_t keyring_ref,
774 const char *type,
775 const char *description,
776 const void *payload,
777 size_t plen,
778 key_perm_t perm,
779 unsigned long flags)
780 {
781 struct keyring_index_key index_key = {
782 .description = description,
783 };
784 struct key_preparsed_payload prep;
785 struct assoc_array_edit *edit;
786 const struct cred *cred = current_cred();
787 struct key *keyring, *key = NULL;
788 key_ref_t key_ref;
789 int ret;
790
791 /* look up the key type to see if it's one of the registered kernel
792 * types */
793 index_key.type = key_type_lookup(type);
794 if (IS_ERR(index_key.type)) {
795 key_ref = ERR_PTR(-ENODEV);
796 goto error;
797 }
798
799 key_ref = ERR_PTR(-EINVAL);
800 if (!index_key.type->instantiate ||
801 (!index_key.description && !index_key.type->preparse))
802 goto error_put_type;
803
804 keyring = key_ref_to_ptr(keyring_ref);
805
806 key_check(keyring);
807
808 key_ref = ERR_PTR(-ENOTDIR);
809 if (keyring->type != &key_type_keyring)
810 goto error_put_type;
811
812 memset(&prep, 0, sizeof(prep));
813 prep.data = payload;
814 prep.datalen = plen;
815 prep.quotalen = index_key.type->def_datalen;
816 prep.trusted = flags & KEY_ALLOC_TRUSTED;
817 prep.expiry = TIME_T_MAX;
818 if (index_key.type->preparse) {
819 ret = index_key.type->preparse(&prep);
820 if (ret < 0) {
821 key_ref = ERR_PTR(ret);
822 goto error_free_prep;
823 }
824 if (!index_key.description)
825 index_key.description = prep.description;
826 key_ref = ERR_PTR(-EINVAL);
827 if (!index_key.description)
828 goto error_free_prep;
829 }
830 index_key.desc_len = strlen(index_key.description);
831
832 key_ref = ERR_PTR(-EPERM);
833 if (!prep.trusted && test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags))
834 goto error_free_prep;
835 flags |= prep.trusted ? KEY_ALLOC_TRUSTED : 0;
836
837 ret = __key_link_begin(keyring, &index_key, &edit);
838 if (ret < 0) {
839 key_ref = ERR_PTR(ret);
840 goto error_free_prep;
841 }
842
843 /* if we're going to allocate a new key, we're going to have
844 * to modify the keyring */
845 ret = key_permission(keyring_ref, KEY_NEED_WRITE);
846 if (ret < 0) {
847 key_ref = ERR_PTR(ret);
848 goto error_link_end;
849 }
850
851 /* if it's possible to update this type of key, search for an existing
852 * key of the same type and description in the destination keyring and
853 * update that instead if possible
854 */
855 if (index_key.type->update) {
856 key_ref = find_key_to_update(keyring_ref, &index_key);
857 if (key_ref)
858 goto found_matching_key;
859 }
860
861 /* if the client doesn't provide, decide on the permissions we want */
862 if (perm == KEY_PERM_UNDEF) {
863 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
864 perm |= KEY_USR_VIEW;
865
866 if (index_key.type->read)
867 perm |= KEY_POS_READ;
868
869 if (index_key.type == &key_type_keyring ||
870 index_key.type->update)
871 perm |= KEY_POS_WRITE;
872 }
873
874 /* allocate a new key */
875 key = key_alloc(index_key.type, index_key.description,
876 cred->fsuid, cred->fsgid, cred, perm, flags);
877 if (IS_ERR(key)) {
878 key_ref = ERR_CAST(key);
879 goto error_link_end;
880 }
881
882 /* instantiate it and link it into the target keyring */
883 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
884 if (ret < 0) {
885 key_put(key);
886 key_ref = ERR_PTR(ret);
887 goto error_link_end;
888 }
889
890 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
891
892 error_link_end:
893 __key_link_end(keyring, &index_key, edit);
894 error_free_prep:
895 if (index_key.type->preparse)
896 index_key.type->free_preparse(&prep);
897 error_put_type:
898 key_type_put(index_key.type);
899 error:
900 return key_ref;
901
902 found_matching_key:
903 /* we found a matching key, so we're going to try to update it
904 * - we can drop the locks first as we have the key pinned
905 */
906 __key_link_end(keyring, &index_key, edit);
907
908 key_ref = __key_update(key_ref, &prep);
909 goto error_free_prep;
910 }
911 EXPORT_SYMBOL(key_create_or_update);
912
913 /**
914 * key_update - Update a key's contents.
915 * @key_ref: The pointer (plus possession flag) to the key.
916 * @payload: The data to be used to update the key.
917 * @plen: The length of @payload.
918 *
919 * Attempt to update the contents of a key with the given payload data. The
920 * caller must be granted Write permission on the key. Negative keys can be
921 * instantiated by this method.
922 *
923 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
924 * type does not support updating. The key type may return other errors.
925 */
926 int key_update(key_ref_t key_ref, const void *payload, size_t plen)
927 {
928 struct key_preparsed_payload prep;
929 struct key *key = key_ref_to_ptr(key_ref);
930 int ret;
931
932 key_check(key);
933
934 /* the key must be writable */
935 ret = key_permission(key_ref, KEY_NEED_WRITE);
936 if (ret < 0)
937 goto error;
938
939 /* attempt to update it if supported */
940 ret = -EOPNOTSUPP;
941 if (!key->type->update)
942 goto error;
943
944 memset(&prep, 0, sizeof(prep));
945 prep.data = payload;
946 prep.datalen = plen;
947 prep.quotalen = key->type->def_datalen;
948 prep.expiry = TIME_T_MAX;
949 if (key->type->preparse) {
950 ret = key->type->preparse(&prep);
951 if (ret < 0)
952 goto error;
953 }
954
955 down_write(&key->sem);
956
957 ret = key->type->update(key, &prep);
958 if (ret == 0)
959 /* updating a negative key instantiates it */
960 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
961
962 up_write(&key->sem);
963
964 error:
965 if (key->type->preparse)
966 key->type->free_preparse(&prep);
967 return ret;
968 }
969 EXPORT_SYMBOL(key_update);
970
971 /**
972 * key_revoke - Revoke a key.
973 * @key: The key to be revoked.
974 *
975 * Mark a key as being revoked and ask the type to free up its resources. The
976 * revocation timeout is set and the key and all its links will be
977 * automatically garbage collected after key_gc_delay amount of time if they
978 * are not manually dealt with first.
979 */
980 void key_revoke(struct key *key)
981 {
982 struct timespec now;
983 time_t time;
984
985 key_check(key);
986
987 /* make sure no one's trying to change or use the key when we mark it
988 * - we tell lockdep that we might nest because we might be revoking an
989 * authorisation key whilst holding the sem on a key we've just
990 * instantiated
991 */
992 down_write_nested(&key->sem, 1);
993 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
994 key->type->revoke)
995 key->type->revoke(key);
996
997 /* set the death time to no more than the expiry time */
998 now = current_kernel_time();
999 time = now.tv_sec;
1000 if (key->revoked_at == 0 || key->revoked_at > time) {
1001 key->revoked_at = time;
1002 key_schedule_gc(key->revoked_at + key_gc_delay);
1003 }
1004
1005 up_write(&key->sem);
1006 }
1007 EXPORT_SYMBOL(key_revoke);
1008
1009 /**
1010 * key_invalidate - Invalidate a key.
1011 * @key: The key to be invalidated.
1012 *
1013 * Mark a key as being invalidated and have it cleaned up immediately. The key
1014 * is ignored by all searches and other operations from this point.
1015 */
1016 void key_invalidate(struct key *key)
1017 {
1018 kenter("%d", key_serial(key));
1019
1020 key_check(key);
1021
1022 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1023 down_write_nested(&key->sem, 1);
1024 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags))
1025 key_schedule_gc_links();
1026 up_write(&key->sem);
1027 }
1028 }
1029 EXPORT_SYMBOL(key_invalidate);
1030
1031 /**
1032 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1033 * @key: The key to be instantiated
1034 * @prep: The preparsed data to load.
1035 *
1036 * Instantiate a key from preparsed data. We assume we can just copy the data
1037 * in directly and clear the old pointers.
1038 *
1039 * This can be pointed to directly by the key type instantiate op pointer.
1040 */
1041 int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1042 {
1043 int ret;
1044
1045 pr_devel("==>%s()\n", __func__);
1046
1047 ret = key_payload_reserve(key, prep->quotalen);
1048 if (ret == 0) {
1049 rcu_assign_keypointer(key, prep->payload.data[0]);
1050 key->payload.data[1] = prep->payload.data[1];
1051 key->payload.data[2] = prep->payload.data[2];
1052 key->payload.data[3] = prep->payload.data[3];
1053 prep->payload.data[0] = NULL;
1054 prep->payload.data[1] = NULL;
1055 prep->payload.data[2] = NULL;
1056 prep->payload.data[3] = NULL;
1057 }
1058 pr_devel("<==%s() = %d\n", __func__, ret);
1059 return ret;
1060 }
1061 EXPORT_SYMBOL(generic_key_instantiate);
1062
1063 /**
1064 * register_key_type - Register a type of key.
1065 * @ktype: The new key type.
1066 *
1067 * Register a new key type.
1068 *
1069 * Returns 0 on success or -EEXIST if a type of this name already exists.
1070 */
1071 int register_key_type(struct key_type *ktype)
1072 {
1073 struct key_type *p;
1074 int ret;
1075
1076 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1077
1078 ret = -EEXIST;
1079 down_write(&key_types_sem);
1080
1081 /* disallow key types with the same name */
1082 list_for_each_entry(p, &key_types_list, link) {
1083 if (strcmp(p->name, ktype->name) == 0)
1084 goto out;
1085 }
1086
1087 /* store the type */
1088 list_add(&ktype->link, &key_types_list);
1089
1090 pr_notice("Key type %s registered\n", ktype->name);
1091 ret = 0;
1092
1093 out:
1094 up_write(&key_types_sem);
1095 return ret;
1096 }
1097 EXPORT_SYMBOL(register_key_type);
1098
1099 /**
1100 * unregister_key_type - Unregister a type of key.
1101 * @ktype: The key type.
1102 *
1103 * Unregister a key type and mark all the extant keys of this type as dead.
1104 * Those keys of this type are then destroyed to get rid of their payloads and
1105 * they and their links will be garbage collected as soon as possible.
1106 */
1107 void unregister_key_type(struct key_type *ktype)
1108 {
1109 down_write(&key_types_sem);
1110 list_del_init(&ktype->link);
1111 downgrade_write(&key_types_sem);
1112 key_gc_keytype(ktype);
1113 pr_notice("Key type %s unregistered\n", ktype->name);
1114 up_read(&key_types_sem);
1115 }
1116 EXPORT_SYMBOL(unregister_key_type);
1117
1118 /*
1119 * Initialise the key management state.
1120 */
1121 void __init key_init(void)
1122 {
1123 /* allocate a slab in which we can store keys */
1124 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1125 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1126
1127 /* add the special key types */
1128 list_add_tail(&key_type_keyring.link, &key_types_list);
1129 list_add_tail(&key_type_dead.link, &key_types_list);
1130 list_add_tail(&key_type_user.link, &key_types_list);
1131 list_add_tail(&key_type_logon.link, &key_types_list);
1132
1133 /* record the root user tracking */
1134 rb_link_node(&root_key_user.node,
1135 NULL,
1136 &key_user_tree.rb_node);
1137
1138 rb_insert_color(&root_key_user.node,
1139 &key_user_tree);
1140 }