Loading...
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
23struct kmem_cache *key_jar;
24struct rb_root key_serial_tree; /* tree of keys indexed by serial */
25DEFINE_SPINLOCK(key_serial_lock);
26
27struct rb_root key_user_tree; /* tree of quota records indexed by UID */
28DEFINE_SPINLOCK(key_user_lock);
29
30unsigned int key_quota_root_maxkeys = 1000000; /* root's key count quota */
31unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
32unsigned int key_quota_maxkeys = 200; /* general key count quota */
33unsigned int key_quota_maxbytes = 20000; /* general key space quota */
34
35static LIST_HEAD(key_types_list);
36static DECLARE_RWSEM(key_types_sem);
37
38/* We serialise key instantiation and link */
39DEFINE_MUTEX(key_construction_mutex);
40
41#ifdef KEY_DEBUGGING
42void __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 */
54struct 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
60try_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 */
112found:
113 atomic_inc(&user->usage);
114 spin_unlock(&key_user_lock);
115 kfree(candidate);
116out:
117 return user;
118}
119
120/*
121 * Dispose of a user structure
122 */
123void 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 */
137static 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
152attempt_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 */
177serial_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 */
224struct 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 if (flags & KEY_ALLOC_BUILT_IN)
300 key->flags |= 1 << KEY_FLAG_BUILTIN;
301
302#ifdef KEY_DEBUGGING
303 key->magic = KEY_DEBUG_MAGIC;
304#endif
305
306 /* let the security module know about the key */
307 ret = security_key_alloc(key, cred, flags);
308 if (ret < 0)
309 goto security_error;
310
311 /* publish the key by giving it a serial number */
312 atomic_inc(&user->nkeys);
313 key_alloc_serial(key);
314
315error:
316 return key;
317
318security_error:
319 kfree(key->description);
320 kmem_cache_free(key_jar, key);
321 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
322 spin_lock(&user->lock);
323 user->qnkeys--;
324 user->qnbytes -= quotalen;
325 spin_unlock(&user->lock);
326 }
327 key_user_put(user);
328 key = ERR_PTR(ret);
329 goto error;
330
331no_memory_3:
332 kmem_cache_free(key_jar, key);
333no_memory_2:
334 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
335 spin_lock(&user->lock);
336 user->qnkeys--;
337 user->qnbytes -= quotalen;
338 spin_unlock(&user->lock);
339 }
340 key_user_put(user);
341no_memory_1:
342 key = ERR_PTR(-ENOMEM);
343 goto error;
344
345no_quota:
346 spin_unlock(&user->lock);
347 key_user_put(user);
348 key = ERR_PTR(-EDQUOT);
349 goto error;
350}
351EXPORT_SYMBOL(key_alloc);
352
353/**
354 * key_payload_reserve - Adjust data quota reservation for the key's payload
355 * @key: The key to make the reservation for.
356 * @datalen: The amount of data payload the caller now wants.
357 *
358 * Adjust the amount of the owning user's key data quota that a key reserves.
359 * If the amount is increased, then -EDQUOT may be returned if there isn't
360 * enough free quota available.
361 *
362 * If successful, 0 is returned.
363 */
364int key_payload_reserve(struct key *key, size_t datalen)
365{
366 int delta = (int)datalen - key->datalen;
367 int ret = 0;
368
369 key_check(key);
370
371 /* contemplate the quota adjustment */
372 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
373 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
374 key_quota_root_maxbytes : key_quota_maxbytes;
375
376 spin_lock(&key->user->lock);
377
378 if (delta > 0 &&
379 (key->user->qnbytes + delta >= maxbytes ||
380 key->user->qnbytes + delta < key->user->qnbytes)) {
381 ret = -EDQUOT;
382 }
383 else {
384 key->user->qnbytes += delta;
385 key->quotalen += delta;
386 }
387 spin_unlock(&key->user->lock);
388 }
389
390 /* change the recorded data length if that didn't generate an error */
391 if (ret == 0)
392 key->datalen = datalen;
393
394 return ret;
395}
396EXPORT_SYMBOL(key_payload_reserve);
397
398/*
399 * Instantiate a key and link it into the target keyring atomically. Must be
400 * called with the target keyring's semaphore writelocked. The target key's
401 * semaphore need not be locked as instantiation is serialised by
402 * key_construction_mutex.
403 */
404static int __key_instantiate_and_link(struct key *key,
405 struct key_preparsed_payload *prep,
406 struct key *keyring,
407 struct key *authkey,
408 struct assoc_array_edit **_edit)
409{
410 int ret, awaken;
411
412 key_check(key);
413 key_check(keyring);
414
415 awaken = 0;
416 ret = -EBUSY;
417
418 mutex_lock(&key_construction_mutex);
419
420 /* can't instantiate twice */
421 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
422 /* instantiate the key */
423 ret = key->type->instantiate(key, prep);
424
425 if (ret == 0) {
426 /* mark the key as being instantiated */
427 atomic_inc(&key->user->nikeys);
428 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
429
430 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
431 awaken = 1;
432
433 /* and link it into the destination keyring */
434 if (keyring) {
435 if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
436 set_bit(KEY_FLAG_KEEP, &key->flags);
437
438 __key_link(key, _edit);
439 }
440
441 /* disable the authorisation key */
442 if (authkey)
443 key_revoke(authkey);
444
445 if (prep->expiry != TIME_T_MAX) {
446 key->expiry = prep->expiry;
447 key_schedule_gc(prep->expiry + key_gc_delay);
448 }
449 }
450 }
451
452 mutex_unlock(&key_construction_mutex);
453
454 /* wake up anyone waiting for a key to be constructed */
455 if (awaken)
456 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
457
458 return ret;
459}
460
461/**
462 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
463 * @key: The key to instantiate.
464 * @data: The data to use to instantiate the keyring.
465 * @datalen: The length of @data.
466 * @keyring: Keyring to create a link in on success (or NULL).
467 * @authkey: The authorisation token permitting instantiation.
468 *
469 * Instantiate a key that's in the uninstantiated state using the provided data
470 * and, if successful, link it in to the destination keyring if one is
471 * supplied.
472 *
473 * If successful, 0 is returned, the authorisation token is revoked and anyone
474 * waiting for the key is woken up. If the key was already instantiated,
475 * -EBUSY will be returned.
476 */
477int key_instantiate_and_link(struct key *key,
478 const void *data,
479 size_t datalen,
480 struct key *keyring,
481 struct key *authkey)
482{
483 struct key_preparsed_payload prep;
484 struct assoc_array_edit *edit;
485 int ret;
486
487 memset(&prep, 0, sizeof(prep));
488 prep.data = data;
489 prep.datalen = datalen;
490 prep.quotalen = key->type->def_datalen;
491 prep.expiry = TIME_T_MAX;
492 if (key->type->preparse) {
493 ret = key->type->preparse(&prep);
494 if (ret < 0)
495 goto error;
496 }
497
498 if (keyring) {
499 ret = __key_link_begin(keyring, &key->index_key, &edit);
500 if (ret < 0)
501 goto error;
502 }
503
504 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
505
506 if (keyring)
507 __key_link_end(keyring, &key->index_key, edit);
508
509error:
510 if (key->type->preparse)
511 key->type->free_preparse(&prep);
512 return ret;
513}
514
515EXPORT_SYMBOL(key_instantiate_and_link);
516
517/**
518 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
519 * @key: The key to instantiate.
520 * @timeout: The timeout on the negative key.
521 * @error: The error to return when the key is hit.
522 * @keyring: Keyring to create a link in on success (or NULL).
523 * @authkey: The authorisation token permitting instantiation.
524 *
525 * Negatively instantiate a key that's in the uninstantiated state and, if
526 * successful, set its timeout and stored error and link it in to the
527 * destination keyring if one is supplied. The key and any links to the key
528 * will be automatically garbage collected after the timeout expires.
529 *
530 * Negative keys are used to rate limit repeated request_key() calls by causing
531 * them to return the stored error code (typically ENOKEY) until the negative
532 * key expires.
533 *
534 * If successful, 0 is returned, the authorisation token is revoked and anyone
535 * waiting for the key is woken up. If the key was already instantiated,
536 * -EBUSY will be returned.
537 */
538int key_reject_and_link(struct key *key,
539 unsigned timeout,
540 unsigned error,
541 struct key *keyring,
542 struct key *authkey)
543{
544 struct assoc_array_edit *edit;
545 struct timespec now;
546 int ret, awaken, link_ret = 0;
547
548 key_check(key);
549 key_check(keyring);
550
551 awaken = 0;
552 ret = -EBUSY;
553
554 if (keyring)
555 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
556
557 mutex_lock(&key_construction_mutex);
558
559 /* can't instantiate twice */
560 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
561 /* mark the key as being negatively instantiated */
562 atomic_inc(&key->user->nikeys);
563 key->reject_error = -error;
564 smp_wmb();
565 set_bit(KEY_FLAG_NEGATIVE, &key->flags);
566 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
567 now = current_kernel_time();
568 key->expiry = now.tv_sec + timeout;
569 key_schedule_gc(key->expiry + key_gc_delay);
570
571 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
572 awaken = 1;
573
574 ret = 0;
575
576 /* and link it into the destination keyring */
577 if (keyring && link_ret == 0)
578 __key_link(key, &edit);
579
580 /* disable the authorisation key */
581 if (authkey)
582 key_revoke(authkey);
583 }
584
585 mutex_unlock(&key_construction_mutex);
586
587 if (keyring)
588 __key_link_end(keyring, &key->index_key, edit);
589
590 /* wake up anyone waiting for a key to be constructed */
591 if (awaken)
592 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
593
594 return ret == 0 ? link_ret : ret;
595}
596EXPORT_SYMBOL(key_reject_and_link);
597
598/**
599 * key_put - Discard a reference to a key.
600 * @key: The key to discard a reference from.
601 *
602 * Discard a reference to a key, and when all the references are gone, we
603 * schedule the cleanup task to come and pull it out of the tree in process
604 * context at some later time.
605 */
606void key_put(struct key *key)
607{
608 if (key) {
609 key_check(key);
610
611 if (atomic_dec_and_test(&key->usage))
612 schedule_work(&key_gc_work);
613 }
614}
615EXPORT_SYMBOL(key_put);
616
617/*
618 * Find a key by its serial number.
619 */
620struct key *key_lookup(key_serial_t id)
621{
622 struct rb_node *n;
623 struct key *key;
624
625 spin_lock(&key_serial_lock);
626
627 /* search the tree for the specified key */
628 n = key_serial_tree.rb_node;
629 while (n) {
630 key = rb_entry(n, struct key, serial_node);
631
632 if (id < key->serial)
633 n = n->rb_left;
634 else if (id > key->serial)
635 n = n->rb_right;
636 else
637 goto found;
638 }
639
640not_found:
641 key = ERR_PTR(-ENOKEY);
642 goto error;
643
644found:
645 /* pretend it doesn't exist if it is awaiting deletion */
646 if (atomic_read(&key->usage) == 0)
647 goto not_found;
648
649 /* this races with key_put(), but that doesn't matter since key_put()
650 * doesn't actually change the key
651 */
652 __key_get(key);
653
654error:
655 spin_unlock(&key_serial_lock);
656 return key;
657}
658
659/*
660 * Find and lock the specified key type against removal.
661 *
662 * We return with the sem read-locked if successful. If the type wasn't
663 * available -ENOKEY is returned instead.
664 */
665struct key_type *key_type_lookup(const char *type)
666{
667 struct key_type *ktype;
668
669 down_read(&key_types_sem);
670
671 /* look up the key type to see if it's one of the registered kernel
672 * types */
673 list_for_each_entry(ktype, &key_types_list, link) {
674 if (strcmp(ktype->name, type) == 0)
675 goto found_kernel_type;
676 }
677
678 up_read(&key_types_sem);
679 ktype = ERR_PTR(-ENOKEY);
680
681found_kernel_type:
682 return ktype;
683}
684
685void key_set_timeout(struct key *key, unsigned timeout)
686{
687 struct timespec now;
688 time_t expiry = 0;
689
690 /* make the changes with the locks held to prevent races */
691 down_write(&key->sem);
692
693 if (timeout > 0) {
694 now = current_kernel_time();
695 expiry = now.tv_sec + timeout;
696 }
697
698 key->expiry = expiry;
699 key_schedule_gc(key->expiry + key_gc_delay);
700
701 up_write(&key->sem);
702}
703EXPORT_SYMBOL_GPL(key_set_timeout);
704
705/*
706 * Unlock a key type locked by key_type_lookup().
707 */
708void key_type_put(struct key_type *ktype)
709{
710 up_read(&key_types_sem);
711}
712
713/*
714 * Attempt to update an existing key.
715 *
716 * The key is given to us with an incremented refcount that we need to discard
717 * if we get an error.
718 */
719static inline key_ref_t __key_update(key_ref_t key_ref,
720 struct key_preparsed_payload *prep)
721{
722 struct key *key = key_ref_to_ptr(key_ref);
723 int ret;
724
725 /* need write permission on the key to update it */
726 ret = key_permission(key_ref, KEY_NEED_WRITE);
727 if (ret < 0)
728 goto error;
729
730 ret = -EEXIST;
731 if (!key->type->update)
732 goto error;
733
734 down_write(&key->sem);
735
736 ret = key->type->update(key, prep);
737 if (ret == 0)
738 /* updating a negative key instantiates it */
739 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
740
741 up_write(&key->sem);
742
743 if (ret < 0)
744 goto error;
745out:
746 return key_ref;
747
748error:
749 key_put(key);
750 key_ref = ERR_PTR(ret);
751 goto out;
752}
753
754/**
755 * key_create_or_update - Update or create and instantiate a key.
756 * @keyring_ref: A pointer to the destination keyring with possession flag.
757 * @type: The type of key.
758 * @description: The searchable description for the key.
759 * @payload: The data to use to instantiate or update the key.
760 * @plen: The length of @payload.
761 * @perm: The permissions mask for a new key.
762 * @flags: The quota flags for a new key.
763 *
764 * Search the destination keyring for a key of the same description and if one
765 * is found, update it, otherwise create and instantiate a new one and create a
766 * link to it from that keyring.
767 *
768 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
769 * concocted.
770 *
771 * Returns a pointer to the new key if successful, -ENODEV if the key type
772 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
773 * caller isn't permitted to modify the keyring or the LSM did not permit
774 * creation of the key.
775 *
776 * On success, the possession flag from the keyring ref will be tacked on to
777 * the key ref before it is returned.
778 */
779key_ref_t key_create_or_update(key_ref_t keyring_ref,
780 const char *type,
781 const char *description,
782 const void *payload,
783 size_t plen,
784 key_perm_t perm,
785 unsigned long flags)
786{
787 struct keyring_index_key index_key = {
788 .description = description,
789 };
790 struct key_preparsed_payload prep;
791 struct assoc_array_edit *edit;
792 const struct cred *cred = current_cred();
793 struct key *keyring, *key = NULL;
794 key_ref_t key_ref;
795 int ret;
796
797 /* look up the key type to see if it's one of the registered kernel
798 * types */
799 index_key.type = key_type_lookup(type);
800 if (IS_ERR(index_key.type)) {
801 key_ref = ERR_PTR(-ENODEV);
802 goto error;
803 }
804
805 key_ref = ERR_PTR(-EINVAL);
806 if (!index_key.type->instantiate ||
807 (!index_key.description && !index_key.type->preparse))
808 goto error_put_type;
809
810 keyring = key_ref_to_ptr(keyring_ref);
811
812 key_check(keyring);
813
814 key_ref = ERR_PTR(-ENOTDIR);
815 if (keyring->type != &key_type_keyring)
816 goto error_put_type;
817
818 memset(&prep, 0, sizeof(prep));
819 prep.data = payload;
820 prep.datalen = plen;
821 prep.quotalen = index_key.type->def_datalen;
822 prep.trusted = flags & KEY_ALLOC_TRUSTED;
823 prep.expiry = TIME_T_MAX;
824 if (index_key.type->preparse) {
825 ret = index_key.type->preparse(&prep);
826 if (ret < 0) {
827 key_ref = ERR_PTR(ret);
828 goto error_free_prep;
829 }
830 if (!index_key.description)
831 index_key.description = prep.description;
832 key_ref = ERR_PTR(-EINVAL);
833 if (!index_key.description)
834 goto error_free_prep;
835 }
836 index_key.desc_len = strlen(index_key.description);
837
838 key_ref = ERR_PTR(-EPERM);
839 if (!prep.trusted && test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags))
840 goto error_free_prep;
841 flags |= prep.trusted ? KEY_ALLOC_TRUSTED : 0;
842
843 ret = __key_link_begin(keyring, &index_key, &edit);
844 if (ret < 0) {
845 key_ref = ERR_PTR(ret);
846 goto error_free_prep;
847 }
848
849 /* if we're going to allocate a new key, we're going to have
850 * to modify the keyring */
851 ret = key_permission(keyring_ref, KEY_NEED_WRITE);
852 if (ret < 0) {
853 key_ref = ERR_PTR(ret);
854 goto error_link_end;
855 }
856
857 /* if it's possible to update this type of key, search for an existing
858 * key of the same type and description in the destination keyring and
859 * update that instead if possible
860 */
861 if (index_key.type->update) {
862 key_ref = find_key_to_update(keyring_ref, &index_key);
863 if (key_ref)
864 goto found_matching_key;
865 }
866
867 /* if the client doesn't provide, decide on the permissions we want */
868 if (perm == KEY_PERM_UNDEF) {
869 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
870 perm |= KEY_USR_VIEW;
871
872 if (index_key.type->read)
873 perm |= KEY_POS_READ;
874
875 if (index_key.type == &key_type_keyring ||
876 index_key.type->update)
877 perm |= KEY_POS_WRITE;
878 }
879
880 /* allocate a new key */
881 key = key_alloc(index_key.type, index_key.description,
882 cred->fsuid, cred->fsgid, cred, perm, flags);
883 if (IS_ERR(key)) {
884 key_ref = ERR_CAST(key);
885 goto error_link_end;
886 }
887
888 /* instantiate it and link it into the target keyring */
889 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
890 if (ret < 0) {
891 key_put(key);
892 key_ref = ERR_PTR(ret);
893 goto error_link_end;
894 }
895
896 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
897
898error_link_end:
899 __key_link_end(keyring, &index_key, edit);
900error_free_prep:
901 if (index_key.type->preparse)
902 index_key.type->free_preparse(&prep);
903error_put_type:
904 key_type_put(index_key.type);
905error:
906 return key_ref;
907
908 found_matching_key:
909 /* we found a matching key, so we're going to try to update it
910 * - we can drop the locks first as we have the key pinned
911 */
912 __key_link_end(keyring, &index_key, edit);
913
914 key_ref = __key_update(key_ref, &prep);
915 goto error_free_prep;
916}
917EXPORT_SYMBOL(key_create_or_update);
918
919/**
920 * key_update - Update a key's contents.
921 * @key_ref: The pointer (plus possession flag) to the key.
922 * @payload: The data to be used to update the key.
923 * @plen: The length of @payload.
924 *
925 * Attempt to update the contents of a key with the given payload data. The
926 * caller must be granted Write permission on the key. Negative keys can be
927 * instantiated by this method.
928 *
929 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
930 * type does not support updating. The key type may return other errors.
931 */
932int key_update(key_ref_t key_ref, const void *payload, size_t plen)
933{
934 struct key_preparsed_payload prep;
935 struct key *key = key_ref_to_ptr(key_ref);
936 int ret;
937
938 key_check(key);
939
940 /* the key must be writable */
941 ret = key_permission(key_ref, KEY_NEED_WRITE);
942 if (ret < 0)
943 goto error;
944
945 /* attempt to update it if supported */
946 ret = -EOPNOTSUPP;
947 if (!key->type->update)
948 goto error;
949
950 memset(&prep, 0, sizeof(prep));
951 prep.data = payload;
952 prep.datalen = plen;
953 prep.quotalen = key->type->def_datalen;
954 prep.expiry = TIME_T_MAX;
955 if (key->type->preparse) {
956 ret = key->type->preparse(&prep);
957 if (ret < 0)
958 goto error;
959 }
960
961 down_write(&key->sem);
962
963 ret = key->type->update(key, &prep);
964 if (ret == 0)
965 /* updating a negative key instantiates it */
966 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
967
968 up_write(&key->sem);
969
970error:
971 if (key->type->preparse)
972 key->type->free_preparse(&prep);
973 return ret;
974}
975EXPORT_SYMBOL(key_update);
976
977/**
978 * key_revoke - Revoke a key.
979 * @key: The key to be revoked.
980 *
981 * Mark a key as being revoked and ask the type to free up its resources. The
982 * revocation timeout is set and the key and all its links will be
983 * automatically garbage collected after key_gc_delay amount of time if they
984 * are not manually dealt with first.
985 */
986void key_revoke(struct key *key)
987{
988 struct timespec now;
989 time_t time;
990
991 key_check(key);
992
993 /* make sure no one's trying to change or use the key when we mark it
994 * - we tell lockdep that we might nest because we might be revoking an
995 * authorisation key whilst holding the sem on a key we've just
996 * instantiated
997 */
998 down_write_nested(&key->sem, 1);
999 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
1000 key->type->revoke)
1001 key->type->revoke(key);
1002
1003 /* set the death time to no more than the expiry time */
1004 now = current_kernel_time();
1005 time = now.tv_sec;
1006 if (key->revoked_at == 0 || key->revoked_at > time) {
1007 key->revoked_at = time;
1008 key_schedule_gc(key->revoked_at + key_gc_delay);
1009 }
1010
1011 up_write(&key->sem);
1012}
1013EXPORT_SYMBOL(key_revoke);
1014
1015/**
1016 * key_invalidate - Invalidate a key.
1017 * @key: The key to be invalidated.
1018 *
1019 * Mark a key as being invalidated and have it cleaned up immediately. The key
1020 * is ignored by all searches and other operations from this point.
1021 */
1022void key_invalidate(struct key *key)
1023{
1024 kenter("%d", key_serial(key));
1025
1026 key_check(key);
1027
1028 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1029 down_write_nested(&key->sem, 1);
1030 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags))
1031 key_schedule_gc_links();
1032 up_write(&key->sem);
1033 }
1034}
1035EXPORT_SYMBOL(key_invalidate);
1036
1037/**
1038 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1039 * @key: The key to be instantiated
1040 * @prep: The preparsed data to load.
1041 *
1042 * Instantiate a key from preparsed data. We assume we can just copy the data
1043 * in directly and clear the old pointers.
1044 *
1045 * This can be pointed to directly by the key type instantiate op pointer.
1046 */
1047int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1048{
1049 int ret;
1050
1051 pr_devel("==>%s()\n", __func__);
1052
1053 ret = key_payload_reserve(key, prep->quotalen);
1054 if (ret == 0) {
1055 rcu_assign_keypointer(key, prep->payload.data[0]);
1056 key->payload.data[1] = prep->payload.data[1];
1057 key->payload.data[2] = prep->payload.data[2];
1058 key->payload.data[3] = prep->payload.data[3];
1059 prep->payload.data[0] = NULL;
1060 prep->payload.data[1] = NULL;
1061 prep->payload.data[2] = NULL;
1062 prep->payload.data[3] = NULL;
1063 }
1064 pr_devel("<==%s() = %d\n", __func__, ret);
1065 return ret;
1066}
1067EXPORT_SYMBOL(generic_key_instantiate);
1068
1069/**
1070 * register_key_type - Register a type of key.
1071 * @ktype: The new key type.
1072 *
1073 * Register a new key type.
1074 *
1075 * Returns 0 on success or -EEXIST if a type of this name already exists.
1076 */
1077int register_key_type(struct key_type *ktype)
1078{
1079 struct key_type *p;
1080 int ret;
1081
1082 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1083
1084 ret = -EEXIST;
1085 down_write(&key_types_sem);
1086
1087 /* disallow key types with the same name */
1088 list_for_each_entry(p, &key_types_list, link) {
1089 if (strcmp(p->name, ktype->name) == 0)
1090 goto out;
1091 }
1092
1093 /* store the type */
1094 list_add(&ktype->link, &key_types_list);
1095
1096 pr_notice("Key type %s registered\n", ktype->name);
1097 ret = 0;
1098
1099out:
1100 up_write(&key_types_sem);
1101 return ret;
1102}
1103EXPORT_SYMBOL(register_key_type);
1104
1105/**
1106 * unregister_key_type - Unregister a type of key.
1107 * @ktype: The key type.
1108 *
1109 * Unregister a key type and mark all the extant keys of this type as dead.
1110 * Those keys of this type are then destroyed to get rid of their payloads and
1111 * they and their links will be garbage collected as soon as possible.
1112 */
1113void unregister_key_type(struct key_type *ktype)
1114{
1115 down_write(&key_types_sem);
1116 list_del_init(&ktype->link);
1117 downgrade_write(&key_types_sem);
1118 key_gc_keytype(ktype);
1119 pr_notice("Key type %s unregistered\n", ktype->name);
1120 up_read(&key_types_sem);
1121}
1122EXPORT_SYMBOL(unregister_key_type);
1123
1124/*
1125 * Initialise the key management state.
1126 */
1127void __init key_init(void)
1128{
1129 /* allocate a slab in which we can store keys */
1130 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1131 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1132
1133 /* add the special key types */
1134 list_add_tail(&key_type_keyring.link, &key_types_list);
1135 list_add_tail(&key_type_dead.link, &key_types_list);
1136 list_add_tail(&key_type_user.link, &key_types_list);
1137 list_add_tail(&key_type_logon.link, &key_types_list);
1138
1139 /* record the root user tracking */
1140 rb_link_node(&root_key_user.node,
1141 NULL,
1142 &key_user_tree.rb_node);
1143
1144 rb_insert_color(&root_key_user.node,
1145 &key_user_tree);
1146}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Basic authentication token and access key management
3 *
4 * Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/export.h>
9#include <linux/init.h>
10#include <linux/poison.h>
11#include <linux/sched.h>
12#include <linux/slab.h>
13#include <linux/security.h>
14#include <linux/workqueue.h>
15#include <linux/random.h>
16#include <linux/err.h>
17#include "internal.h"
18
19struct kmem_cache *key_jar;
20struct rb_root key_serial_tree; /* tree of keys indexed by serial */
21DEFINE_SPINLOCK(key_serial_lock);
22
23struct rb_root key_user_tree; /* tree of quota records indexed by UID */
24DEFINE_SPINLOCK(key_user_lock);
25
26unsigned int key_quota_root_maxkeys = 1000000; /* root's key count quota */
27unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
28unsigned int key_quota_maxkeys = 200; /* general key count quota */
29unsigned int key_quota_maxbytes = 20000; /* general key space quota */
30
31static LIST_HEAD(key_types_list);
32static DECLARE_RWSEM(key_types_sem);
33
34/* We serialise key instantiation and link */
35DEFINE_MUTEX(key_construction_mutex);
36
37#ifdef KEY_DEBUGGING
38void __key_check(const struct key *key)
39{
40 printk("__key_check: key %p {%08x} should be {%08x}\n",
41 key, key->magic, KEY_DEBUG_MAGIC);
42 BUG();
43}
44#endif
45
46/*
47 * Get the key quota record for a user, allocating a new record if one doesn't
48 * already exist.
49 */
50struct key_user *key_user_lookup(kuid_t uid)
51{
52 struct key_user *candidate = NULL, *user;
53 struct rb_node *parent, **p;
54
55try_again:
56 parent = NULL;
57 p = &key_user_tree.rb_node;
58 spin_lock(&key_user_lock);
59
60 /* search the tree for a user record with a matching UID */
61 while (*p) {
62 parent = *p;
63 user = rb_entry(parent, struct key_user, node);
64
65 if (uid_lt(uid, user->uid))
66 p = &(*p)->rb_left;
67 else if (uid_gt(uid, user->uid))
68 p = &(*p)->rb_right;
69 else
70 goto found;
71 }
72
73 /* if we get here, we failed to find a match in the tree */
74 if (!candidate) {
75 /* allocate a candidate user record if we don't already have
76 * one */
77 spin_unlock(&key_user_lock);
78
79 user = NULL;
80 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
81 if (unlikely(!candidate))
82 goto out;
83
84 /* the allocation may have scheduled, so we need to repeat the
85 * search lest someone else added the record whilst we were
86 * asleep */
87 goto try_again;
88 }
89
90 /* if we get here, then the user record still hadn't appeared on the
91 * second pass - so we use the candidate record */
92 refcount_set(&candidate->usage, 1);
93 atomic_set(&candidate->nkeys, 0);
94 atomic_set(&candidate->nikeys, 0);
95 candidate->uid = uid;
96 candidate->qnkeys = 0;
97 candidate->qnbytes = 0;
98 spin_lock_init(&candidate->lock);
99 mutex_init(&candidate->cons_lock);
100
101 rb_link_node(&candidate->node, parent, p);
102 rb_insert_color(&candidate->node, &key_user_tree);
103 spin_unlock(&key_user_lock);
104 user = candidate;
105 goto out;
106
107 /* okay - we found a user record for this UID */
108found:
109 refcount_inc(&user->usage);
110 spin_unlock(&key_user_lock);
111 kfree(candidate);
112out:
113 return user;
114}
115
116/*
117 * Dispose of a user structure
118 */
119void key_user_put(struct key_user *user)
120{
121 if (refcount_dec_and_lock(&user->usage, &key_user_lock)) {
122 rb_erase(&user->node, &key_user_tree);
123 spin_unlock(&key_user_lock);
124
125 kfree(user);
126 }
127}
128
129/*
130 * Allocate a serial number for a key. These are assigned randomly to avoid
131 * security issues through covert channel problems.
132 */
133static inline void key_alloc_serial(struct key *key)
134{
135 struct rb_node *parent, **p;
136 struct key *xkey;
137
138 /* propose a random serial number and look for a hole for it in the
139 * serial number tree */
140 do {
141 get_random_bytes(&key->serial, sizeof(key->serial));
142
143 key->serial >>= 1; /* negative numbers are not permitted */
144 } while (key->serial < 3);
145
146 spin_lock(&key_serial_lock);
147
148attempt_insertion:
149 parent = NULL;
150 p = &key_serial_tree.rb_node;
151
152 while (*p) {
153 parent = *p;
154 xkey = rb_entry(parent, struct key, serial_node);
155
156 if (key->serial < xkey->serial)
157 p = &(*p)->rb_left;
158 else if (key->serial > xkey->serial)
159 p = &(*p)->rb_right;
160 else
161 goto serial_exists;
162 }
163
164 /* we've found a suitable hole - arrange for this key to occupy it */
165 rb_link_node(&key->serial_node, parent, p);
166 rb_insert_color(&key->serial_node, &key_serial_tree);
167
168 spin_unlock(&key_serial_lock);
169 return;
170
171 /* we found a key with the proposed serial number - walk the tree from
172 * that point looking for the next unused serial number */
173serial_exists:
174 for (;;) {
175 key->serial++;
176 if (key->serial < 3) {
177 key->serial = 3;
178 goto attempt_insertion;
179 }
180
181 parent = rb_next(parent);
182 if (!parent)
183 goto attempt_insertion;
184
185 xkey = rb_entry(parent, struct key, serial_node);
186 if (key->serial < xkey->serial)
187 goto attempt_insertion;
188 }
189}
190
191/**
192 * key_alloc - Allocate a key of the specified type.
193 * @type: The type of key to allocate.
194 * @desc: The key description to allow the key to be searched out.
195 * @uid: The owner of the new key.
196 * @gid: The group ID for the new key's group permissions.
197 * @cred: The credentials specifying UID namespace.
198 * @perm: The permissions mask of the new key.
199 * @flags: Flags specifying quota properties.
200 * @restrict_link: Optional link restriction for new keyrings.
201 *
202 * Allocate a key of the specified type with the attributes given. The key is
203 * returned in an uninstantiated state and the caller needs to instantiate the
204 * key before returning.
205 *
206 * The restrict_link structure (if not NULL) will be freed when the
207 * keyring is destroyed, so it must be dynamically allocated.
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 */
224struct 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 struct key_restriction *restrict_link)
228{
229 struct key_user *user = NULL;
230 struct key *key;
231 size_t desclen, quotalen;
232 int ret;
233
234 key = ERR_PTR(-EINVAL);
235 if (!desc || !*desc)
236 goto error;
237
238 if (type->vet_description) {
239 ret = type->vet_description(desc);
240 if (ret < 0) {
241 key = ERR_PTR(ret);
242 goto error;
243 }
244 }
245
246 desclen = strlen(desc);
247 quotalen = desclen + 1 + type->def_datalen;
248
249 /* get hold of the key tracking for this user */
250 user = key_user_lookup(uid);
251 if (!user)
252 goto no_memory_1;
253
254 /* check that the user's quota permits allocation of another key and
255 * its description */
256 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
257 unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
258 key_quota_root_maxkeys : key_quota_maxkeys;
259 unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
260 key_quota_root_maxbytes : key_quota_maxbytes;
261
262 spin_lock(&user->lock);
263 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
264 if (user->qnkeys + 1 > maxkeys ||
265 user->qnbytes + quotalen > maxbytes ||
266 user->qnbytes + quotalen < user->qnbytes)
267 goto no_quota;
268 }
269
270 user->qnkeys++;
271 user->qnbytes += quotalen;
272 spin_unlock(&user->lock);
273 }
274
275 /* allocate and initialise the key and its description */
276 key = kmem_cache_zalloc(key_jar, GFP_KERNEL);
277 if (!key)
278 goto no_memory_2;
279
280 key->index_key.desc_len = desclen;
281 key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
282 if (!key->index_key.description)
283 goto no_memory_3;
284 key->index_key.type = type;
285 key_set_index_key(&key->index_key);
286
287 refcount_set(&key->usage, 1);
288 init_rwsem(&key->sem);
289 lockdep_set_class(&key->sem, &type->lock_class);
290 key->user = user;
291 key->quotalen = quotalen;
292 key->datalen = type->def_datalen;
293 key->uid = uid;
294 key->gid = gid;
295 key->perm = perm;
296 key->restrict_link = restrict_link;
297 key->last_used_at = ktime_get_real_seconds();
298
299 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
300 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
301 if (flags & KEY_ALLOC_BUILT_IN)
302 key->flags |= 1 << KEY_FLAG_BUILTIN;
303 if (flags & KEY_ALLOC_UID_KEYRING)
304 key->flags |= 1 << KEY_FLAG_UID_KEYRING;
305
306#ifdef KEY_DEBUGGING
307 key->magic = KEY_DEBUG_MAGIC;
308#endif
309
310 /* let the security module know about the key */
311 ret = security_key_alloc(key, cred, flags);
312 if (ret < 0)
313 goto security_error;
314
315 /* publish the key by giving it a serial number */
316 refcount_inc(&key->domain_tag->usage);
317 atomic_inc(&user->nkeys);
318 key_alloc_serial(key);
319
320error:
321 return key;
322
323security_error:
324 kfree(key->description);
325 kmem_cache_free(key_jar, key);
326 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
327 spin_lock(&user->lock);
328 user->qnkeys--;
329 user->qnbytes -= quotalen;
330 spin_unlock(&user->lock);
331 }
332 key_user_put(user);
333 key = ERR_PTR(ret);
334 goto error;
335
336no_memory_3:
337 kmem_cache_free(key_jar, key);
338no_memory_2:
339 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
340 spin_lock(&user->lock);
341 user->qnkeys--;
342 user->qnbytes -= quotalen;
343 spin_unlock(&user->lock);
344 }
345 key_user_put(user);
346no_memory_1:
347 key = ERR_PTR(-ENOMEM);
348 goto error;
349
350no_quota:
351 spin_unlock(&user->lock);
352 key_user_put(user);
353 key = ERR_PTR(-EDQUOT);
354 goto error;
355}
356EXPORT_SYMBOL(key_alloc);
357
358/**
359 * key_payload_reserve - Adjust data quota reservation for the key's payload
360 * @key: The key to make the reservation for.
361 * @datalen: The amount of data payload the caller now wants.
362 *
363 * Adjust the amount of the owning user's key data quota that a key reserves.
364 * If the amount is increased, then -EDQUOT may be returned if there isn't
365 * enough free quota available.
366 *
367 * If successful, 0 is returned.
368 */
369int key_payload_reserve(struct key *key, size_t datalen)
370{
371 int delta = (int)datalen - key->datalen;
372 int ret = 0;
373
374 key_check(key);
375
376 /* contemplate the quota adjustment */
377 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
378 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
379 key_quota_root_maxbytes : key_quota_maxbytes;
380
381 spin_lock(&key->user->lock);
382
383 if (delta > 0 &&
384 (key->user->qnbytes + delta >= maxbytes ||
385 key->user->qnbytes + delta < key->user->qnbytes)) {
386 ret = -EDQUOT;
387 }
388 else {
389 key->user->qnbytes += delta;
390 key->quotalen += delta;
391 }
392 spin_unlock(&key->user->lock);
393 }
394
395 /* change the recorded data length if that didn't generate an error */
396 if (ret == 0)
397 key->datalen = datalen;
398
399 return ret;
400}
401EXPORT_SYMBOL(key_payload_reserve);
402
403/*
404 * Change the key state to being instantiated.
405 */
406static void mark_key_instantiated(struct key *key, int reject_error)
407{
408 /* Commit the payload before setting the state; barrier versus
409 * key_read_state().
410 */
411 smp_store_release(&key->state,
412 (reject_error < 0) ? reject_error : KEY_IS_POSITIVE);
413}
414
415/*
416 * Instantiate a key and link it into the target keyring atomically. Must be
417 * called with the target keyring's semaphore writelocked. The target key's
418 * semaphore need not be locked as instantiation is serialised by
419 * key_construction_mutex.
420 */
421static int __key_instantiate_and_link(struct key *key,
422 struct key_preparsed_payload *prep,
423 struct key *keyring,
424 struct key *authkey,
425 struct assoc_array_edit **_edit)
426{
427 int ret, awaken;
428
429 key_check(key);
430 key_check(keyring);
431
432 awaken = 0;
433 ret = -EBUSY;
434
435 mutex_lock(&key_construction_mutex);
436
437 /* can't instantiate twice */
438 if (key->state == KEY_IS_UNINSTANTIATED) {
439 /* instantiate the key */
440 ret = key->type->instantiate(key, prep);
441
442 if (ret == 0) {
443 /* mark the key as being instantiated */
444 atomic_inc(&key->user->nikeys);
445 mark_key_instantiated(key, 0);
446
447 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
448 awaken = 1;
449
450 /* and link it into the destination keyring */
451 if (keyring) {
452 if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
453 set_bit(KEY_FLAG_KEEP, &key->flags);
454
455 __key_link(key, _edit);
456 }
457
458 /* disable the authorisation key */
459 if (authkey)
460 key_invalidate(authkey);
461
462 if (prep->expiry != TIME64_MAX) {
463 key->expiry = prep->expiry;
464 key_schedule_gc(prep->expiry + key_gc_delay);
465 }
466 }
467 }
468
469 mutex_unlock(&key_construction_mutex);
470
471 /* wake up anyone waiting for a key to be constructed */
472 if (awaken)
473 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
474
475 return ret;
476}
477
478/**
479 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
480 * @key: The key to instantiate.
481 * @data: The data to use to instantiate the keyring.
482 * @datalen: The length of @data.
483 * @keyring: Keyring to create a link in on success (or NULL).
484 * @authkey: The authorisation token permitting instantiation.
485 *
486 * Instantiate a key that's in the uninstantiated state using the provided data
487 * and, if successful, link it in to the destination keyring if one is
488 * supplied.
489 *
490 * If successful, 0 is returned, the authorisation token is revoked and anyone
491 * waiting for the key is woken up. If the key was already instantiated,
492 * -EBUSY will be returned.
493 */
494int key_instantiate_and_link(struct key *key,
495 const void *data,
496 size_t datalen,
497 struct key *keyring,
498 struct key *authkey)
499{
500 struct key_preparsed_payload prep;
501 struct assoc_array_edit *edit = NULL;
502 int ret;
503
504 memset(&prep, 0, sizeof(prep));
505 prep.data = data;
506 prep.datalen = datalen;
507 prep.quotalen = key->type->def_datalen;
508 prep.expiry = TIME64_MAX;
509 if (key->type->preparse) {
510 ret = key->type->preparse(&prep);
511 if (ret < 0)
512 goto error;
513 }
514
515 if (keyring) {
516 ret = __key_link_lock(keyring, &key->index_key);
517 if (ret < 0)
518 goto error;
519
520 ret = __key_link_begin(keyring, &key->index_key, &edit);
521 if (ret < 0)
522 goto error_link_end;
523
524 if (keyring->restrict_link && keyring->restrict_link->check) {
525 struct key_restriction *keyres = keyring->restrict_link;
526
527 ret = keyres->check(keyring, key->type, &prep.payload,
528 keyres->key);
529 if (ret < 0)
530 goto error_link_end;
531 }
532 }
533
534 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
535
536error_link_end:
537 if (keyring)
538 __key_link_end(keyring, &key->index_key, edit);
539
540error:
541 if (key->type->preparse)
542 key->type->free_preparse(&prep);
543 return ret;
544}
545
546EXPORT_SYMBOL(key_instantiate_and_link);
547
548/**
549 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
550 * @key: The key to instantiate.
551 * @timeout: The timeout on the negative key.
552 * @error: The error to return when the key is hit.
553 * @keyring: Keyring to create a link in on success (or NULL).
554 * @authkey: The authorisation token permitting instantiation.
555 *
556 * Negatively instantiate a key that's in the uninstantiated state and, if
557 * successful, set its timeout and stored error and link it in to the
558 * destination keyring if one is supplied. The key and any links to the key
559 * will be automatically garbage collected after the timeout expires.
560 *
561 * Negative keys are used to rate limit repeated request_key() calls by causing
562 * them to return the stored error code (typically ENOKEY) until the negative
563 * key expires.
564 *
565 * If successful, 0 is returned, the authorisation token is revoked and anyone
566 * waiting for the key is woken up. If the key was already instantiated,
567 * -EBUSY will be returned.
568 */
569int key_reject_and_link(struct key *key,
570 unsigned timeout,
571 unsigned error,
572 struct key *keyring,
573 struct key *authkey)
574{
575 struct assoc_array_edit *edit = NULL;
576 int ret, awaken, link_ret = 0;
577
578 key_check(key);
579 key_check(keyring);
580
581 awaken = 0;
582 ret = -EBUSY;
583
584 if (keyring) {
585 if (keyring->restrict_link)
586 return -EPERM;
587
588 link_ret = __key_link_lock(keyring, &key->index_key);
589 if (link_ret == 0) {
590 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
591 if (link_ret < 0)
592 __key_link_end(keyring, &key->index_key, edit);
593 }
594 }
595
596 mutex_lock(&key_construction_mutex);
597
598 /* can't instantiate twice */
599 if (key->state == KEY_IS_UNINSTANTIATED) {
600 /* mark the key as being negatively instantiated */
601 atomic_inc(&key->user->nikeys);
602 mark_key_instantiated(key, -error);
603 key->expiry = ktime_get_real_seconds() + timeout;
604 key_schedule_gc(key->expiry + key_gc_delay);
605
606 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
607 awaken = 1;
608
609 ret = 0;
610
611 /* and link it into the destination keyring */
612 if (keyring && link_ret == 0)
613 __key_link(key, &edit);
614
615 /* disable the authorisation key */
616 if (authkey)
617 key_invalidate(authkey);
618 }
619
620 mutex_unlock(&key_construction_mutex);
621
622 if (keyring && link_ret == 0)
623 __key_link_end(keyring, &key->index_key, edit);
624
625 /* wake up anyone waiting for a key to be constructed */
626 if (awaken)
627 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
628
629 return ret == 0 ? link_ret : ret;
630}
631EXPORT_SYMBOL(key_reject_and_link);
632
633/**
634 * key_put - Discard a reference to a key.
635 * @key: The key to discard a reference from.
636 *
637 * Discard a reference to a key, and when all the references are gone, we
638 * schedule the cleanup task to come and pull it out of the tree in process
639 * context at some later time.
640 */
641void key_put(struct key *key)
642{
643 if (key) {
644 key_check(key);
645
646 if (refcount_dec_and_test(&key->usage))
647 schedule_work(&key_gc_work);
648 }
649}
650EXPORT_SYMBOL(key_put);
651
652/*
653 * Find a key by its serial number.
654 */
655struct key *key_lookup(key_serial_t id)
656{
657 struct rb_node *n;
658 struct key *key;
659
660 spin_lock(&key_serial_lock);
661
662 /* search the tree for the specified key */
663 n = key_serial_tree.rb_node;
664 while (n) {
665 key = rb_entry(n, struct key, serial_node);
666
667 if (id < key->serial)
668 n = n->rb_left;
669 else if (id > key->serial)
670 n = n->rb_right;
671 else
672 goto found;
673 }
674
675not_found:
676 key = ERR_PTR(-ENOKEY);
677 goto error;
678
679found:
680 /* A key is allowed to be looked up only if someone still owns a
681 * reference to it - otherwise it's awaiting the gc.
682 */
683 if (!refcount_inc_not_zero(&key->usage))
684 goto not_found;
685
686error:
687 spin_unlock(&key_serial_lock);
688 return key;
689}
690
691/*
692 * Find and lock the specified key type against removal.
693 *
694 * We return with the sem read-locked if successful. If the type wasn't
695 * available -ENOKEY is returned instead.
696 */
697struct key_type *key_type_lookup(const char *type)
698{
699 struct key_type *ktype;
700
701 down_read(&key_types_sem);
702
703 /* look up the key type to see if it's one of the registered kernel
704 * types */
705 list_for_each_entry(ktype, &key_types_list, link) {
706 if (strcmp(ktype->name, type) == 0)
707 goto found_kernel_type;
708 }
709
710 up_read(&key_types_sem);
711 ktype = ERR_PTR(-ENOKEY);
712
713found_kernel_type:
714 return ktype;
715}
716
717void key_set_timeout(struct key *key, unsigned timeout)
718{
719 time64_t expiry = 0;
720
721 /* make the changes with the locks held to prevent races */
722 down_write(&key->sem);
723
724 if (timeout > 0)
725 expiry = ktime_get_real_seconds() + timeout;
726
727 key->expiry = expiry;
728 key_schedule_gc(key->expiry + key_gc_delay);
729
730 up_write(&key->sem);
731}
732EXPORT_SYMBOL_GPL(key_set_timeout);
733
734/*
735 * Unlock a key type locked by key_type_lookup().
736 */
737void key_type_put(struct key_type *ktype)
738{
739 up_read(&key_types_sem);
740}
741
742/*
743 * Attempt to update an existing key.
744 *
745 * The key is given to us with an incremented refcount that we need to discard
746 * if we get an error.
747 */
748static inline key_ref_t __key_update(key_ref_t key_ref,
749 struct key_preparsed_payload *prep)
750{
751 struct key *key = key_ref_to_ptr(key_ref);
752 int ret;
753
754 /* need write permission on the key to update it */
755 ret = key_permission(key_ref, KEY_NEED_WRITE);
756 if (ret < 0)
757 goto error;
758
759 ret = -EEXIST;
760 if (!key->type->update)
761 goto error;
762
763 down_write(&key->sem);
764
765 ret = key->type->update(key, prep);
766 if (ret == 0)
767 /* Updating a negative key positively instantiates it */
768 mark_key_instantiated(key, 0);
769
770 up_write(&key->sem);
771
772 if (ret < 0)
773 goto error;
774out:
775 return key_ref;
776
777error:
778 key_put(key);
779 key_ref = ERR_PTR(ret);
780 goto out;
781}
782
783/**
784 * key_create_or_update - Update or create and instantiate a key.
785 * @keyring_ref: A pointer to the destination keyring with possession flag.
786 * @type: The type of key.
787 * @description: The searchable description for the key.
788 * @payload: The data to use to instantiate or update the key.
789 * @plen: The length of @payload.
790 * @perm: The permissions mask for a new key.
791 * @flags: The quota flags for a new key.
792 *
793 * Search the destination keyring for a key of the same description and if one
794 * is found, update it, otherwise create and instantiate a new one and create a
795 * link to it from that keyring.
796 *
797 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
798 * concocted.
799 *
800 * Returns a pointer to the new key if successful, -ENODEV if the key type
801 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
802 * caller isn't permitted to modify the keyring or the LSM did not permit
803 * creation of the key.
804 *
805 * On success, the possession flag from the keyring ref will be tacked on to
806 * the key ref before it is returned.
807 */
808key_ref_t key_create_or_update(key_ref_t keyring_ref,
809 const char *type,
810 const char *description,
811 const void *payload,
812 size_t plen,
813 key_perm_t perm,
814 unsigned long flags)
815{
816 struct keyring_index_key index_key = {
817 .description = description,
818 };
819 struct key_preparsed_payload prep;
820 struct assoc_array_edit *edit = NULL;
821 const struct cred *cred = current_cred();
822 struct key *keyring, *key = NULL;
823 key_ref_t key_ref;
824 int ret;
825 struct key_restriction *restrict_link = NULL;
826
827 /* look up the key type to see if it's one of the registered kernel
828 * types */
829 index_key.type = key_type_lookup(type);
830 if (IS_ERR(index_key.type)) {
831 key_ref = ERR_PTR(-ENODEV);
832 goto error;
833 }
834
835 key_ref = ERR_PTR(-EINVAL);
836 if (!index_key.type->instantiate ||
837 (!index_key.description && !index_key.type->preparse))
838 goto error_put_type;
839
840 keyring = key_ref_to_ptr(keyring_ref);
841
842 key_check(keyring);
843
844 if (!(flags & KEY_ALLOC_BYPASS_RESTRICTION))
845 restrict_link = keyring->restrict_link;
846
847 key_ref = ERR_PTR(-ENOTDIR);
848 if (keyring->type != &key_type_keyring)
849 goto error_put_type;
850
851 memset(&prep, 0, sizeof(prep));
852 prep.data = payload;
853 prep.datalen = plen;
854 prep.quotalen = index_key.type->def_datalen;
855 prep.expiry = TIME64_MAX;
856 if (index_key.type->preparse) {
857 ret = index_key.type->preparse(&prep);
858 if (ret < 0) {
859 key_ref = ERR_PTR(ret);
860 goto error_free_prep;
861 }
862 if (!index_key.description)
863 index_key.description = prep.description;
864 key_ref = ERR_PTR(-EINVAL);
865 if (!index_key.description)
866 goto error_free_prep;
867 }
868 index_key.desc_len = strlen(index_key.description);
869 key_set_index_key(&index_key);
870
871 ret = __key_link_lock(keyring, &index_key);
872 if (ret < 0) {
873 key_ref = ERR_PTR(ret);
874 goto error_free_prep;
875 }
876
877 ret = __key_link_begin(keyring, &index_key, &edit);
878 if (ret < 0) {
879 key_ref = ERR_PTR(ret);
880 goto error_link_end;
881 }
882
883 if (restrict_link && restrict_link->check) {
884 ret = restrict_link->check(keyring, index_key.type,
885 &prep.payload, restrict_link->key);
886 if (ret < 0) {
887 key_ref = ERR_PTR(ret);
888 goto error_link_end;
889 }
890 }
891
892 /* if we're going to allocate a new key, we're going to have
893 * to modify the keyring */
894 ret = key_permission(keyring_ref, KEY_NEED_WRITE);
895 if (ret < 0) {
896 key_ref = ERR_PTR(ret);
897 goto error_link_end;
898 }
899
900 /* if it's possible to update this type of key, search for an existing
901 * key of the same type and description in the destination keyring and
902 * update that instead if possible
903 */
904 if (index_key.type->update) {
905 key_ref = find_key_to_update(keyring_ref, &index_key);
906 if (key_ref)
907 goto found_matching_key;
908 }
909
910 /* if the client doesn't provide, decide on the permissions we want */
911 if (perm == KEY_PERM_UNDEF) {
912 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
913 perm |= KEY_USR_VIEW;
914
915 if (index_key.type->read)
916 perm |= KEY_POS_READ;
917
918 if (index_key.type == &key_type_keyring ||
919 index_key.type->update)
920 perm |= KEY_POS_WRITE;
921 }
922
923 /* allocate a new key */
924 key = key_alloc(index_key.type, index_key.description,
925 cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
926 if (IS_ERR(key)) {
927 key_ref = ERR_CAST(key);
928 goto error_link_end;
929 }
930
931 /* instantiate it and link it into the target keyring */
932 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
933 if (ret < 0) {
934 key_put(key);
935 key_ref = ERR_PTR(ret);
936 goto error_link_end;
937 }
938
939 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
940
941error_link_end:
942 __key_link_end(keyring, &index_key, edit);
943error_free_prep:
944 if (index_key.type->preparse)
945 index_key.type->free_preparse(&prep);
946error_put_type:
947 key_type_put(index_key.type);
948error:
949 return key_ref;
950
951 found_matching_key:
952 /* we found a matching key, so we're going to try to update it
953 * - we can drop the locks first as we have the key pinned
954 */
955 __key_link_end(keyring, &index_key, edit);
956
957 key = key_ref_to_ptr(key_ref);
958 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) {
959 ret = wait_for_key_construction(key, true);
960 if (ret < 0) {
961 key_ref_put(key_ref);
962 key_ref = ERR_PTR(ret);
963 goto error_free_prep;
964 }
965 }
966
967 key_ref = __key_update(key_ref, &prep);
968 goto error_free_prep;
969}
970EXPORT_SYMBOL(key_create_or_update);
971
972/**
973 * key_update - Update a key's contents.
974 * @key_ref: The pointer (plus possession flag) to the key.
975 * @payload: The data to be used to update the key.
976 * @plen: The length of @payload.
977 *
978 * Attempt to update the contents of a key with the given payload data. The
979 * caller must be granted Write permission on the key. Negative keys can be
980 * instantiated by this method.
981 *
982 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
983 * type does not support updating. The key type may return other errors.
984 */
985int key_update(key_ref_t key_ref, const void *payload, size_t plen)
986{
987 struct key_preparsed_payload prep;
988 struct key *key = key_ref_to_ptr(key_ref);
989 int ret;
990
991 key_check(key);
992
993 /* the key must be writable */
994 ret = key_permission(key_ref, KEY_NEED_WRITE);
995 if (ret < 0)
996 return ret;
997
998 /* attempt to update it if supported */
999 if (!key->type->update)
1000 return -EOPNOTSUPP;
1001
1002 memset(&prep, 0, sizeof(prep));
1003 prep.data = payload;
1004 prep.datalen = plen;
1005 prep.quotalen = key->type->def_datalen;
1006 prep.expiry = TIME64_MAX;
1007 if (key->type->preparse) {
1008 ret = key->type->preparse(&prep);
1009 if (ret < 0)
1010 goto error;
1011 }
1012
1013 down_write(&key->sem);
1014
1015 ret = key->type->update(key, &prep);
1016 if (ret == 0)
1017 /* Updating a negative key positively instantiates it */
1018 mark_key_instantiated(key, 0);
1019
1020 up_write(&key->sem);
1021
1022error:
1023 if (key->type->preparse)
1024 key->type->free_preparse(&prep);
1025 return ret;
1026}
1027EXPORT_SYMBOL(key_update);
1028
1029/**
1030 * key_revoke - Revoke a key.
1031 * @key: The key to be revoked.
1032 *
1033 * Mark a key as being revoked and ask the type to free up its resources. The
1034 * revocation timeout is set and the key and all its links will be
1035 * automatically garbage collected after key_gc_delay amount of time if they
1036 * are not manually dealt with first.
1037 */
1038void key_revoke(struct key *key)
1039{
1040 time64_t time;
1041
1042 key_check(key);
1043
1044 /* make sure no one's trying to change or use the key when we mark it
1045 * - we tell lockdep that we might nest because we might be revoking an
1046 * authorisation key whilst holding the sem on a key we've just
1047 * instantiated
1048 */
1049 down_write_nested(&key->sem, 1);
1050 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
1051 key->type->revoke)
1052 key->type->revoke(key);
1053
1054 /* set the death time to no more than the expiry time */
1055 time = ktime_get_real_seconds();
1056 if (key->revoked_at == 0 || key->revoked_at > time) {
1057 key->revoked_at = time;
1058 key_schedule_gc(key->revoked_at + key_gc_delay);
1059 }
1060
1061 up_write(&key->sem);
1062}
1063EXPORT_SYMBOL(key_revoke);
1064
1065/**
1066 * key_invalidate - Invalidate a key.
1067 * @key: The key to be invalidated.
1068 *
1069 * Mark a key as being invalidated and have it cleaned up immediately. The key
1070 * is ignored by all searches and other operations from this point.
1071 */
1072void key_invalidate(struct key *key)
1073{
1074 kenter("%d", key_serial(key));
1075
1076 key_check(key);
1077
1078 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1079 down_write_nested(&key->sem, 1);
1080 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags))
1081 key_schedule_gc_links();
1082 up_write(&key->sem);
1083 }
1084}
1085EXPORT_SYMBOL(key_invalidate);
1086
1087/**
1088 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1089 * @key: The key to be instantiated
1090 * @prep: The preparsed data to load.
1091 *
1092 * Instantiate a key from preparsed data. We assume we can just copy the data
1093 * in directly and clear the old pointers.
1094 *
1095 * This can be pointed to directly by the key type instantiate op pointer.
1096 */
1097int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1098{
1099 int ret;
1100
1101 pr_devel("==>%s()\n", __func__);
1102
1103 ret = key_payload_reserve(key, prep->quotalen);
1104 if (ret == 0) {
1105 rcu_assign_keypointer(key, prep->payload.data[0]);
1106 key->payload.data[1] = prep->payload.data[1];
1107 key->payload.data[2] = prep->payload.data[2];
1108 key->payload.data[3] = prep->payload.data[3];
1109 prep->payload.data[0] = NULL;
1110 prep->payload.data[1] = NULL;
1111 prep->payload.data[2] = NULL;
1112 prep->payload.data[3] = NULL;
1113 }
1114 pr_devel("<==%s() = %d\n", __func__, ret);
1115 return ret;
1116}
1117EXPORT_SYMBOL(generic_key_instantiate);
1118
1119/**
1120 * register_key_type - Register a type of key.
1121 * @ktype: The new key type.
1122 *
1123 * Register a new key type.
1124 *
1125 * Returns 0 on success or -EEXIST if a type of this name already exists.
1126 */
1127int register_key_type(struct key_type *ktype)
1128{
1129 struct key_type *p;
1130 int ret;
1131
1132 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1133
1134 ret = -EEXIST;
1135 down_write(&key_types_sem);
1136
1137 /* disallow key types with the same name */
1138 list_for_each_entry(p, &key_types_list, link) {
1139 if (strcmp(p->name, ktype->name) == 0)
1140 goto out;
1141 }
1142
1143 /* store the type */
1144 list_add(&ktype->link, &key_types_list);
1145
1146 pr_notice("Key type %s registered\n", ktype->name);
1147 ret = 0;
1148
1149out:
1150 up_write(&key_types_sem);
1151 return ret;
1152}
1153EXPORT_SYMBOL(register_key_type);
1154
1155/**
1156 * unregister_key_type - Unregister a type of key.
1157 * @ktype: The key type.
1158 *
1159 * Unregister a key type and mark all the extant keys of this type as dead.
1160 * Those keys of this type are then destroyed to get rid of their payloads and
1161 * they and their links will be garbage collected as soon as possible.
1162 */
1163void unregister_key_type(struct key_type *ktype)
1164{
1165 down_write(&key_types_sem);
1166 list_del_init(&ktype->link);
1167 downgrade_write(&key_types_sem);
1168 key_gc_keytype(ktype);
1169 pr_notice("Key type %s unregistered\n", ktype->name);
1170 up_read(&key_types_sem);
1171}
1172EXPORT_SYMBOL(unregister_key_type);
1173
1174/*
1175 * Initialise the key management state.
1176 */
1177void __init key_init(void)
1178{
1179 /* allocate a slab in which we can store keys */
1180 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1181 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1182
1183 /* add the special key types */
1184 list_add_tail(&key_type_keyring.link, &key_types_list);
1185 list_add_tail(&key_type_dead.link, &key_types_list);
1186 list_add_tail(&key_type_user.link, &key_types_list);
1187 list_add_tail(&key_type_logon.link, &key_types_list);
1188
1189 /* record the root user tracking */
1190 rb_link_node(&root_key_user.node,
1191 NULL,
1192 &key_user_tree.rb_node);
1193
1194 rb_insert_color(&root_key_user.node,
1195 &key_user_tree);
1196}