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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/ima.h>
17#include <linux/err.h>
18#include "internal.h"
19
20struct kmem_cache *key_jar;
21struct rb_root key_serial_tree; /* tree of keys indexed by serial */
22DEFINE_SPINLOCK(key_serial_lock);
23
24struct rb_root key_user_tree; /* tree of quota records indexed by UID */
25DEFINE_SPINLOCK(key_user_lock);
26
27unsigned int key_quota_root_maxkeys = 1000000; /* root's key count quota */
28unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
29unsigned int key_quota_maxkeys = 200; /* general key count quota */
30unsigned int key_quota_maxbytes = 20000; /* general key space quota */
31
32static LIST_HEAD(key_types_list);
33static DECLARE_RWSEM(key_types_sem);
34
35/* We serialise key instantiation and link */
36DEFINE_MUTEX(key_construction_mutex);
37
38#ifdef KEY_DEBUGGING
39void __key_check(const struct key *key)
40{
41 printk("__key_check: key %p {%08x} should be {%08x}\n",
42 key, key->magic, KEY_DEBUG_MAGIC);
43 BUG();
44}
45#endif
46
47/*
48 * Get the key quota record for a user, allocating a new record if one doesn't
49 * already exist.
50 */
51struct key_user *key_user_lookup(kuid_t uid)
52{
53 struct key_user *candidate = NULL, *user;
54 struct rb_node *parent, **p;
55
56try_again:
57 parent = NULL;
58 p = &key_user_tree.rb_node;
59 spin_lock(&key_user_lock);
60
61 /* search the tree for a user record with a matching UID */
62 while (*p) {
63 parent = *p;
64 user = rb_entry(parent, struct key_user, node);
65
66 if (uid_lt(uid, user->uid))
67 p = &(*p)->rb_left;
68 else if (uid_gt(uid, user->uid))
69 p = &(*p)->rb_right;
70 else
71 goto found;
72 }
73
74 /* if we get here, we failed to find a match in the tree */
75 if (!candidate) {
76 /* allocate a candidate user record if we don't already have
77 * one */
78 spin_unlock(&key_user_lock);
79
80 user = NULL;
81 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
82 if (unlikely(!candidate))
83 goto out;
84
85 /* the allocation may have scheduled, so we need to repeat the
86 * search lest someone else added the record whilst we were
87 * asleep */
88 goto try_again;
89 }
90
91 /* if we get here, then the user record still hadn't appeared on the
92 * second pass - so we use the candidate record */
93 refcount_set(&candidate->usage, 1);
94 atomic_set(&candidate->nkeys, 0);
95 atomic_set(&candidate->nikeys, 0);
96 candidate->uid = uid;
97 candidate->qnkeys = 0;
98 candidate->qnbytes = 0;
99 spin_lock_init(&candidate->lock);
100 mutex_init(&candidate->cons_lock);
101
102 rb_link_node(&candidate->node, parent, p);
103 rb_insert_color(&candidate->node, &key_user_tree);
104 spin_unlock(&key_user_lock);
105 user = candidate;
106 goto out;
107
108 /* okay - we found a user record for this UID */
109found:
110 refcount_inc(&user->usage);
111 spin_unlock(&key_user_lock);
112 kfree(candidate);
113out:
114 return user;
115}
116
117/*
118 * Dispose of a user structure
119 */
120void key_user_put(struct key_user *user)
121{
122 if (refcount_dec_and_lock(&user->usage, &key_user_lock)) {
123 rb_erase(&user->node, &key_user_tree);
124 spin_unlock(&key_user_lock);
125
126 kfree(user);
127 }
128}
129
130/*
131 * Allocate a serial number for a key. These are assigned randomly to avoid
132 * security issues through covert channel problems.
133 */
134static inline void key_alloc_serial(struct key *key)
135{
136 struct rb_node *parent, **p;
137 struct key *xkey;
138
139 /* propose a random serial number and look for a hole for it in the
140 * serial number tree */
141 do {
142 get_random_bytes(&key->serial, sizeof(key->serial));
143
144 key->serial >>= 1; /* negative numbers are not permitted */
145 } while (key->serial < 3);
146
147 spin_lock(&key_serial_lock);
148
149attempt_insertion:
150 parent = NULL;
151 p = &key_serial_tree.rb_node;
152
153 while (*p) {
154 parent = *p;
155 xkey = rb_entry(parent, struct key, serial_node);
156
157 if (key->serial < xkey->serial)
158 p = &(*p)->rb_left;
159 else if (key->serial > xkey->serial)
160 p = &(*p)->rb_right;
161 else
162 goto serial_exists;
163 }
164
165 /* we've found a suitable hole - arrange for this key to occupy it */
166 rb_link_node(&key->serial_node, parent, p);
167 rb_insert_color(&key->serial_node, &key_serial_tree);
168
169 spin_unlock(&key_serial_lock);
170 return;
171
172 /* we found a key with the proposed serial number - walk the tree from
173 * that point looking for the next unused serial number */
174serial_exists:
175 for (;;) {
176 key->serial++;
177 if (key->serial < 3) {
178 key->serial = 3;
179 goto attempt_insertion;
180 }
181
182 parent = rb_next(parent);
183 if (!parent)
184 goto attempt_insertion;
185
186 xkey = rb_entry(parent, struct key, serial_node);
187 if (key->serial < xkey->serial)
188 goto attempt_insertion;
189 }
190}
191
192/**
193 * key_alloc - Allocate a key of the specified type.
194 * @type: The type of key to allocate.
195 * @desc: The key description to allow the key to be searched out.
196 * @uid: The owner of the new key.
197 * @gid: The group ID for the new key's group permissions.
198 * @cred: The credentials specifying UID namespace.
199 * @perm: The permissions mask of the new key.
200 * @flags: Flags specifying quota properties.
201 * @restrict_link: Optional link restriction for new keyrings.
202 *
203 * Allocate a key of the specified type with the attributes given. The key is
204 * returned in an uninstantiated state and the caller needs to instantiate the
205 * key before returning.
206 *
207 * The restrict_link structure (if not NULL) will be freed when the
208 * keyring is destroyed, so it must be dynamically allocated.
209 *
210 * The user's key count quota is updated to reflect the creation of the key and
211 * the user's key data quota has the default for the key type reserved. The
212 * instantiation function should amend this as necessary. If insufficient
213 * quota is available, -EDQUOT will be returned.
214 *
215 * The LSM security modules can prevent a key being created, in which case
216 * -EACCES will be returned.
217 *
218 * Returns a pointer to the new key if successful and an error code otherwise.
219 *
220 * Note that the caller needs to ensure the key type isn't uninstantiated.
221 * Internally this can be done by locking key_types_sem. Externally, this can
222 * be done by either never unregistering the key type, or making sure
223 * key_alloc() calls don't race with module unloading.
224 */
225struct key *key_alloc(struct key_type *type, const char *desc,
226 kuid_t uid, kgid_t gid, const struct cred *cred,
227 key_perm_t perm, unsigned long flags,
228 struct key_restriction *restrict_link)
229{
230 struct key_user *user = NULL;
231 struct key *key;
232 size_t desclen, quotalen;
233 int ret;
234
235 key = ERR_PTR(-EINVAL);
236 if (!desc || !*desc)
237 goto error;
238
239 if (type->vet_description) {
240 ret = type->vet_description(desc);
241 if (ret < 0) {
242 key = ERR_PTR(ret);
243 goto error;
244 }
245 }
246
247 desclen = strlen(desc);
248 quotalen = desclen + 1 + type->def_datalen;
249
250 /* get hold of the key tracking for this user */
251 user = key_user_lookup(uid);
252 if (!user)
253 goto no_memory_1;
254
255 /* check that the user's quota permits allocation of another key and
256 * its description */
257 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
258 unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
259 key_quota_root_maxkeys : key_quota_maxkeys;
260 unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
261 key_quota_root_maxbytes : key_quota_maxbytes;
262
263 spin_lock(&user->lock);
264 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
265 if (user->qnkeys + 1 > maxkeys ||
266 user->qnbytes + quotalen > maxbytes ||
267 user->qnbytes + quotalen < user->qnbytes)
268 goto no_quota;
269 }
270
271 user->qnkeys++;
272 user->qnbytes += quotalen;
273 spin_unlock(&user->lock);
274 }
275
276 /* allocate and initialise the key and its description */
277 key = kmem_cache_zalloc(key_jar, GFP_KERNEL);
278 if (!key)
279 goto no_memory_2;
280
281 key->index_key.desc_len = desclen;
282 key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
283 if (!key->index_key.description)
284 goto no_memory_3;
285 key->index_key.type = type;
286 key_set_index_key(&key->index_key);
287
288 refcount_set(&key->usage, 1);
289 init_rwsem(&key->sem);
290 lockdep_set_class(&key->sem, &type->lock_class);
291 key->user = user;
292 key->quotalen = quotalen;
293 key->datalen = type->def_datalen;
294 key->uid = uid;
295 key->gid = gid;
296 key->perm = perm;
297 key->restrict_link = restrict_link;
298 key->last_used_at = ktime_get_real_seconds();
299
300 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
301 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
302 if (flags & KEY_ALLOC_BUILT_IN)
303 key->flags |= 1 << KEY_FLAG_BUILTIN;
304 if (flags & KEY_ALLOC_UID_KEYRING)
305 key->flags |= 1 << KEY_FLAG_UID_KEYRING;
306
307#ifdef KEY_DEBUGGING
308 key->magic = KEY_DEBUG_MAGIC;
309#endif
310
311 /* let the security module know about the key */
312 ret = security_key_alloc(key, cred, flags);
313 if (ret < 0)
314 goto security_error;
315
316 /* publish the key by giving it a serial number */
317 refcount_inc(&key->domain_tag->usage);
318 atomic_inc(&user->nkeys);
319 key_alloc_serial(key);
320
321error:
322 return key;
323
324security_error:
325 kfree(key->description);
326 kmem_cache_free(key_jar, key);
327 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
328 spin_lock(&user->lock);
329 user->qnkeys--;
330 user->qnbytes -= quotalen;
331 spin_unlock(&user->lock);
332 }
333 key_user_put(user);
334 key = ERR_PTR(ret);
335 goto error;
336
337no_memory_3:
338 kmem_cache_free(key_jar, key);
339no_memory_2:
340 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
341 spin_lock(&user->lock);
342 user->qnkeys--;
343 user->qnbytes -= quotalen;
344 spin_unlock(&user->lock);
345 }
346 key_user_put(user);
347no_memory_1:
348 key = ERR_PTR(-ENOMEM);
349 goto error;
350
351no_quota:
352 spin_unlock(&user->lock);
353 key_user_put(user);
354 key = ERR_PTR(-EDQUOT);
355 goto error;
356}
357EXPORT_SYMBOL(key_alloc);
358
359/**
360 * key_payload_reserve - Adjust data quota reservation for the key's payload
361 * @key: The key to make the reservation for.
362 * @datalen: The amount of data payload the caller now wants.
363 *
364 * Adjust the amount of the owning user's key data quota that a key reserves.
365 * If the amount is increased, then -EDQUOT may be returned if there isn't
366 * enough free quota available.
367 *
368 * If successful, 0 is returned.
369 */
370int key_payload_reserve(struct key *key, size_t datalen)
371{
372 int delta = (int)datalen - key->datalen;
373 int ret = 0;
374
375 key_check(key);
376
377 /* contemplate the quota adjustment */
378 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
379 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
380 key_quota_root_maxbytes : key_quota_maxbytes;
381
382 spin_lock(&key->user->lock);
383
384 if (delta > 0 &&
385 (key->user->qnbytes + delta > maxbytes ||
386 key->user->qnbytes + delta < key->user->qnbytes)) {
387 ret = -EDQUOT;
388 }
389 else {
390 key->user->qnbytes += delta;
391 key->quotalen += delta;
392 }
393 spin_unlock(&key->user->lock);
394 }
395
396 /* change the recorded data length if that didn't generate an error */
397 if (ret == 0)
398 key->datalen = datalen;
399
400 return ret;
401}
402EXPORT_SYMBOL(key_payload_reserve);
403
404/*
405 * Change the key state to being instantiated.
406 */
407static void mark_key_instantiated(struct key *key, int reject_error)
408{
409 /* Commit the payload before setting the state; barrier versus
410 * key_read_state().
411 */
412 smp_store_release(&key->state,
413 (reject_error < 0) ? reject_error : KEY_IS_POSITIVE);
414}
415
416/*
417 * Instantiate a key and link it into the target keyring atomically. Must be
418 * called with the target keyring's semaphore writelocked. The target key's
419 * semaphore need not be locked as instantiation is serialised by
420 * key_construction_mutex.
421 */
422static int __key_instantiate_and_link(struct key *key,
423 struct key_preparsed_payload *prep,
424 struct key *keyring,
425 struct key *authkey,
426 struct assoc_array_edit **_edit)
427{
428 int ret, awaken;
429
430 key_check(key);
431 key_check(keyring);
432
433 awaken = 0;
434 ret = -EBUSY;
435
436 mutex_lock(&key_construction_mutex);
437
438 /* can't instantiate twice */
439 if (key->state == KEY_IS_UNINSTANTIATED) {
440 /* instantiate the key */
441 ret = key->type->instantiate(key, prep);
442
443 if (ret == 0) {
444 /* mark the key as being instantiated */
445 atomic_inc(&key->user->nikeys);
446 mark_key_instantiated(key, 0);
447 notify_key(key, NOTIFY_KEY_INSTANTIATED, 0);
448
449 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
450 awaken = 1;
451
452 /* and link it into the destination keyring */
453 if (keyring) {
454 if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
455 set_bit(KEY_FLAG_KEEP, &key->flags);
456
457 __key_link(keyring, key, _edit);
458 }
459
460 /* disable the authorisation key */
461 if (authkey)
462 key_invalidate(authkey);
463
464 if (prep->expiry != TIME64_MAX) {
465 key->expiry = prep->expiry;
466 key_schedule_gc(prep->expiry + key_gc_delay);
467 }
468 }
469 }
470
471 mutex_unlock(&key_construction_mutex);
472
473 /* wake up anyone waiting for a key to be constructed */
474 if (awaken)
475 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
476
477 return ret;
478}
479
480/**
481 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
482 * @key: The key to instantiate.
483 * @data: The data to use to instantiate the keyring.
484 * @datalen: The length of @data.
485 * @keyring: Keyring to create a link in on success (or NULL).
486 * @authkey: The authorisation token permitting instantiation.
487 *
488 * Instantiate a key that's in the uninstantiated state using the provided data
489 * and, if successful, link it in to the destination keyring if one is
490 * supplied.
491 *
492 * If successful, 0 is returned, the authorisation token is revoked and anyone
493 * waiting for the key is woken up. If the key was already instantiated,
494 * -EBUSY will be returned.
495 */
496int key_instantiate_and_link(struct key *key,
497 const void *data,
498 size_t datalen,
499 struct key *keyring,
500 struct key *authkey)
501{
502 struct key_preparsed_payload prep;
503 struct assoc_array_edit *edit = NULL;
504 int ret;
505
506 memset(&prep, 0, sizeof(prep));
507 prep.data = data;
508 prep.datalen = datalen;
509 prep.quotalen = key->type->def_datalen;
510 prep.expiry = TIME64_MAX;
511 if (key->type->preparse) {
512 ret = key->type->preparse(&prep);
513 if (ret < 0)
514 goto error;
515 }
516
517 if (keyring) {
518 ret = __key_link_lock(keyring, &key->index_key);
519 if (ret < 0)
520 goto error;
521
522 ret = __key_link_begin(keyring, &key->index_key, &edit);
523 if (ret < 0)
524 goto error_link_end;
525
526 if (keyring->restrict_link && keyring->restrict_link->check) {
527 struct key_restriction *keyres = keyring->restrict_link;
528
529 ret = keyres->check(keyring, key->type, &prep.payload,
530 keyres->key);
531 if (ret < 0)
532 goto error_link_end;
533 }
534 }
535
536 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
537
538error_link_end:
539 if (keyring)
540 __key_link_end(keyring, &key->index_key, edit);
541
542error:
543 if (key->type->preparse)
544 key->type->free_preparse(&prep);
545 return ret;
546}
547
548EXPORT_SYMBOL(key_instantiate_and_link);
549
550/**
551 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
552 * @key: The key to instantiate.
553 * @timeout: The timeout on the negative key.
554 * @error: The error to return when the key is hit.
555 * @keyring: Keyring to create a link in on success (or NULL).
556 * @authkey: The authorisation token permitting instantiation.
557 *
558 * Negatively instantiate a key that's in the uninstantiated state and, if
559 * successful, set its timeout and stored error and link it in to the
560 * destination keyring if one is supplied. The key and any links to the key
561 * will be automatically garbage collected after the timeout expires.
562 *
563 * Negative keys are used to rate limit repeated request_key() calls by causing
564 * them to return the stored error code (typically ENOKEY) until the negative
565 * key expires.
566 *
567 * If successful, 0 is returned, the authorisation token is revoked and anyone
568 * waiting for the key is woken up. If the key was already instantiated,
569 * -EBUSY will be returned.
570 */
571int key_reject_and_link(struct key *key,
572 unsigned timeout,
573 unsigned error,
574 struct key *keyring,
575 struct key *authkey)
576{
577 struct assoc_array_edit *edit = NULL;
578 int ret, awaken, link_ret = 0;
579
580 key_check(key);
581 key_check(keyring);
582
583 awaken = 0;
584 ret = -EBUSY;
585
586 if (keyring) {
587 if (keyring->restrict_link)
588 return -EPERM;
589
590 link_ret = __key_link_lock(keyring, &key->index_key);
591 if (link_ret == 0) {
592 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
593 if (link_ret < 0)
594 __key_link_end(keyring, &key->index_key, edit);
595 }
596 }
597
598 mutex_lock(&key_construction_mutex);
599
600 /* can't instantiate twice */
601 if (key->state == KEY_IS_UNINSTANTIATED) {
602 /* mark the key as being negatively instantiated */
603 atomic_inc(&key->user->nikeys);
604 mark_key_instantiated(key, -error);
605 notify_key(key, NOTIFY_KEY_INSTANTIATED, -error);
606 key->expiry = ktime_get_real_seconds() + timeout;
607 key_schedule_gc(key->expiry + key_gc_delay);
608
609 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
610 awaken = 1;
611
612 ret = 0;
613
614 /* and link it into the destination keyring */
615 if (keyring && link_ret == 0)
616 __key_link(keyring, key, &edit);
617
618 /* disable the authorisation key */
619 if (authkey)
620 key_invalidate(authkey);
621 }
622
623 mutex_unlock(&key_construction_mutex);
624
625 if (keyring && link_ret == 0)
626 __key_link_end(keyring, &key->index_key, edit);
627
628 /* wake up anyone waiting for a key to be constructed */
629 if (awaken)
630 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
631
632 return ret == 0 ? link_ret : ret;
633}
634EXPORT_SYMBOL(key_reject_and_link);
635
636/**
637 * key_put - Discard a reference to a key.
638 * @key: The key to discard a reference from.
639 *
640 * Discard a reference to a key, and when all the references are gone, we
641 * schedule the cleanup task to come and pull it out of the tree in process
642 * context at some later time.
643 */
644void key_put(struct key *key)
645{
646 if (key) {
647 key_check(key);
648
649 if (refcount_dec_and_test(&key->usage))
650 schedule_work(&key_gc_work);
651 }
652}
653EXPORT_SYMBOL(key_put);
654
655/*
656 * Find a key by its serial number.
657 */
658struct key *key_lookup(key_serial_t id)
659{
660 struct rb_node *n;
661 struct key *key;
662
663 spin_lock(&key_serial_lock);
664
665 /* search the tree for the specified key */
666 n = key_serial_tree.rb_node;
667 while (n) {
668 key = rb_entry(n, struct key, serial_node);
669
670 if (id < key->serial)
671 n = n->rb_left;
672 else if (id > key->serial)
673 n = n->rb_right;
674 else
675 goto found;
676 }
677
678not_found:
679 key = ERR_PTR(-ENOKEY);
680 goto error;
681
682found:
683 /* A key is allowed to be looked up only if someone still owns a
684 * reference to it - otherwise it's awaiting the gc.
685 */
686 if (!refcount_inc_not_zero(&key->usage))
687 goto not_found;
688
689error:
690 spin_unlock(&key_serial_lock);
691 return key;
692}
693
694/*
695 * Find and lock the specified key type against removal.
696 *
697 * We return with the sem read-locked if successful. If the type wasn't
698 * available -ENOKEY is returned instead.
699 */
700struct key_type *key_type_lookup(const char *type)
701{
702 struct key_type *ktype;
703
704 down_read(&key_types_sem);
705
706 /* look up the key type to see if it's one of the registered kernel
707 * types */
708 list_for_each_entry(ktype, &key_types_list, link) {
709 if (strcmp(ktype->name, type) == 0)
710 goto found_kernel_type;
711 }
712
713 up_read(&key_types_sem);
714 ktype = ERR_PTR(-ENOKEY);
715
716found_kernel_type:
717 return ktype;
718}
719
720void key_set_timeout(struct key *key, unsigned timeout)
721{
722 time64_t expiry = 0;
723
724 /* make the changes with the locks held to prevent races */
725 down_write(&key->sem);
726
727 if (timeout > 0)
728 expiry = ktime_get_real_seconds() + timeout;
729
730 key->expiry = expiry;
731 key_schedule_gc(key->expiry + key_gc_delay);
732
733 up_write(&key->sem);
734}
735EXPORT_SYMBOL_GPL(key_set_timeout);
736
737/*
738 * Unlock a key type locked by key_type_lookup().
739 */
740void key_type_put(struct key_type *ktype)
741{
742 up_read(&key_types_sem);
743}
744
745/*
746 * Attempt to update an existing key.
747 *
748 * The key is given to us with an incremented refcount that we need to discard
749 * if we get an error.
750 */
751static inline key_ref_t __key_update(key_ref_t key_ref,
752 struct key_preparsed_payload *prep)
753{
754 struct key *key = key_ref_to_ptr(key_ref);
755 int ret;
756
757 /* need write permission on the key to update it */
758 ret = key_permission(key_ref, KEY_NEED_WRITE);
759 if (ret < 0)
760 goto error;
761
762 ret = -EEXIST;
763 if (!key->type->update)
764 goto error;
765
766 down_write(&key->sem);
767
768 ret = key->type->update(key, prep);
769 if (ret == 0) {
770 /* Updating a negative key positively instantiates it */
771 mark_key_instantiated(key, 0);
772 notify_key(key, NOTIFY_KEY_UPDATED, 0);
773 }
774
775 up_write(&key->sem);
776
777 if (ret < 0)
778 goto error;
779out:
780 return key_ref;
781
782error:
783 key_put(key);
784 key_ref = ERR_PTR(ret);
785 goto out;
786}
787
788/**
789 * key_create_or_update - Update or create and instantiate a key.
790 * @keyring_ref: A pointer to the destination keyring with possession flag.
791 * @type: The type of key.
792 * @description: The searchable description for the key.
793 * @payload: The data to use to instantiate or update the key.
794 * @plen: The length of @payload.
795 * @perm: The permissions mask for a new key.
796 * @flags: The quota flags for a new key.
797 *
798 * Search the destination keyring for a key of the same description and if one
799 * is found, update it, otherwise create and instantiate a new one and create a
800 * link to it from that keyring.
801 *
802 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
803 * concocted.
804 *
805 * Returns a pointer to the new key if successful, -ENODEV if the key type
806 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
807 * caller isn't permitted to modify the keyring or the LSM did not permit
808 * creation of the key.
809 *
810 * On success, the possession flag from the keyring ref will be tacked on to
811 * the key ref before it is returned.
812 */
813key_ref_t key_create_or_update(key_ref_t keyring_ref,
814 const char *type,
815 const char *description,
816 const void *payload,
817 size_t plen,
818 key_perm_t perm,
819 unsigned long flags)
820{
821 struct keyring_index_key index_key = {
822 .description = description,
823 };
824 struct key_preparsed_payload prep;
825 struct assoc_array_edit *edit = NULL;
826 const struct cred *cred = current_cred();
827 struct key *keyring, *key = NULL;
828 key_ref_t key_ref;
829 int ret;
830 struct key_restriction *restrict_link = NULL;
831
832 /* look up the key type to see if it's one of the registered kernel
833 * types */
834 index_key.type = key_type_lookup(type);
835 if (IS_ERR(index_key.type)) {
836 key_ref = ERR_PTR(-ENODEV);
837 goto error;
838 }
839
840 key_ref = ERR_PTR(-EINVAL);
841 if (!index_key.type->instantiate ||
842 (!index_key.description && !index_key.type->preparse))
843 goto error_put_type;
844
845 keyring = key_ref_to_ptr(keyring_ref);
846
847 key_check(keyring);
848
849 if (!(flags & KEY_ALLOC_BYPASS_RESTRICTION))
850 restrict_link = keyring->restrict_link;
851
852 key_ref = ERR_PTR(-ENOTDIR);
853 if (keyring->type != &key_type_keyring)
854 goto error_put_type;
855
856 memset(&prep, 0, sizeof(prep));
857 prep.data = payload;
858 prep.datalen = plen;
859 prep.quotalen = index_key.type->def_datalen;
860 prep.expiry = TIME64_MAX;
861 if (index_key.type->preparse) {
862 ret = index_key.type->preparse(&prep);
863 if (ret < 0) {
864 key_ref = ERR_PTR(ret);
865 goto error_free_prep;
866 }
867 if (!index_key.description)
868 index_key.description = prep.description;
869 key_ref = ERR_PTR(-EINVAL);
870 if (!index_key.description)
871 goto error_free_prep;
872 }
873 index_key.desc_len = strlen(index_key.description);
874 key_set_index_key(&index_key);
875
876 ret = __key_link_lock(keyring, &index_key);
877 if (ret < 0) {
878 key_ref = ERR_PTR(ret);
879 goto error_free_prep;
880 }
881
882 ret = __key_link_begin(keyring, &index_key, &edit);
883 if (ret < 0) {
884 key_ref = ERR_PTR(ret);
885 goto error_link_end;
886 }
887
888 if (restrict_link && restrict_link->check) {
889 ret = restrict_link->check(keyring, index_key.type,
890 &prep.payload, restrict_link->key);
891 if (ret < 0) {
892 key_ref = ERR_PTR(ret);
893 goto error_link_end;
894 }
895 }
896
897 /* if we're going to allocate a new key, we're going to have
898 * to modify the keyring */
899 ret = key_permission(keyring_ref, KEY_NEED_WRITE);
900 if (ret < 0) {
901 key_ref = ERR_PTR(ret);
902 goto error_link_end;
903 }
904
905 /* if it's possible to update this type of key, search for an existing
906 * key of the same type and description in the destination keyring and
907 * update that instead if possible
908 */
909 if (index_key.type->update) {
910 key_ref = find_key_to_update(keyring_ref, &index_key);
911 if (key_ref)
912 goto found_matching_key;
913 }
914
915 /* if the client doesn't provide, decide on the permissions we want */
916 if (perm == KEY_PERM_UNDEF) {
917 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
918 perm |= KEY_USR_VIEW;
919
920 if (index_key.type->read)
921 perm |= KEY_POS_READ;
922
923 if (index_key.type == &key_type_keyring ||
924 index_key.type->update)
925 perm |= KEY_POS_WRITE;
926 }
927
928 /* allocate a new key */
929 key = key_alloc(index_key.type, index_key.description,
930 cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
931 if (IS_ERR(key)) {
932 key_ref = ERR_CAST(key);
933 goto error_link_end;
934 }
935
936 /* instantiate it and link it into the target keyring */
937 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
938 if (ret < 0) {
939 key_put(key);
940 key_ref = ERR_PTR(ret);
941 goto error_link_end;
942 }
943
944 ima_post_key_create_or_update(keyring, key, payload, plen,
945 flags, true);
946
947 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
948
949error_link_end:
950 __key_link_end(keyring, &index_key, edit);
951error_free_prep:
952 if (index_key.type->preparse)
953 index_key.type->free_preparse(&prep);
954error_put_type:
955 key_type_put(index_key.type);
956error:
957 return key_ref;
958
959 found_matching_key:
960 /* we found a matching key, so we're going to try to update it
961 * - we can drop the locks first as we have the key pinned
962 */
963 __key_link_end(keyring, &index_key, edit);
964
965 key = key_ref_to_ptr(key_ref);
966 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) {
967 ret = wait_for_key_construction(key, true);
968 if (ret < 0) {
969 key_ref_put(key_ref);
970 key_ref = ERR_PTR(ret);
971 goto error_free_prep;
972 }
973 }
974
975 key_ref = __key_update(key_ref, &prep);
976
977 if (!IS_ERR(key_ref))
978 ima_post_key_create_or_update(keyring, key,
979 payload, plen,
980 flags, false);
981
982 goto error_free_prep;
983}
984EXPORT_SYMBOL(key_create_or_update);
985
986/**
987 * key_update - Update a key's contents.
988 * @key_ref: The pointer (plus possession flag) to the key.
989 * @payload: The data to be used to update the key.
990 * @plen: The length of @payload.
991 *
992 * Attempt to update the contents of a key with the given payload data. The
993 * caller must be granted Write permission on the key. Negative keys can be
994 * instantiated by this method.
995 *
996 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
997 * type does not support updating. The key type may return other errors.
998 */
999int key_update(key_ref_t key_ref, const void *payload, size_t plen)
1000{
1001 struct key_preparsed_payload prep;
1002 struct key *key = key_ref_to_ptr(key_ref);
1003 int ret;
1004
1005 key_check(key);
1006
1007 /* the key must be writable */
1008 ret = key_permission(key_ref, KEY_NEED_WRITE);
1009 if (ret < 0)
1010 return ret;
1011
1012 /* attempt to update it if supported */
1013 if (!key->type->update)
1014 return -EOPNOTSUPP;
1015
1016 memset(&prep, 0, sizeof(prep));
1017 prep.data = payload;
1018 prep.datalen = plen;
1019 prep.quotalen = key->type->def_datalen;
1020 prep.expiry = TIME64_MAX;
1021 if (key->type->preparse) {
1022 ret = key->type->preparse(&prep);
1023 if (ret < 0)
1024 goto error;
1025 }
1026
1027 down_write(&key->sem);
1028
1029 ret = key->type->update(key, &prep);
1030 if (ret == 0) {
1031 /* Updating a negative key positively instantiates it */
1032 mark_key_instantiated(key, 0);
1033 notify_key(key, NOTIFY_KEY_UPDATED, 0);
1034 }
1035
1036 up_write(&key->sem);
1037
1038error:
1039 if (key->type->preparse)
1040 key->type->free_preparse(&prep);
1041 return ret;
1042}
1043EXPORT_SYMBOL(key_update);
1044
1045/**
1046 * key_revoke - Revoke a key.
1047 * @key: The key to be revoked.
1048 *
1049 * Mark a key as being revoked and ask the type to free up its resources. The
1050 * revocation timeout is set and the key and all its links will be
1051 * automatically garbage collected after key_gc_delay amount of time if they
1052 * are not manually dealt with first.
1053 */
1054void key_revoke(struct key *key)
1055{
1056 time64_t time;
1057
1058 key_check(key);
1059
1060 /* make sure no one's trying to change or use the key when we mark it
1061 * - we tell lockdep that we might nest because we might be revoking an
1062 * authorisation key whilst holding the sem on a key we've just
1063 * instantiated
1064 */
1065 down_write_nested(&key->sem, 1);
1066 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags)) {
1067 notify_key(key, NOTIFY_KEY_REVOKED, 0);
1068 if (key->type->revoke)
1069 key->type->revoke(key);
1070
1071 /* set the death time to no more than the expiry time */
1072 time = ktime_get_real_seconds();
1073 if (key->revoked_at == 0 || key->revoked_at > time) {
1074 key->revoked_at = time;
1075 key_schedule_gc(key->revoked_at + key_gc_delay);
1076 }
1077 }
1078
1079 up_write(&key->sem);
1080}
1081EXPORT_SYMBOL(key_revoke);
1082
1083/**
1084 * key_invalidate - Invalidate a key.
1085 * @key: The key to be invalidated.
1086 *
1087 * Mark a key as being invalidated and have it cleaned up immediately. The key
1088 * is ignored by all searches and other operations from this point.
1089 */
1090void key_invalidate(struct key *key)
1091{
1092 kenter("%d", key_serial(key));
1093
1094 key_check(key);
1095
1096 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1097 down_write_nested(&key->sem, 1);
1098 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1099 notify_key(key, NOTIFY_KEY_INVALIDATED, 0);
1100 key_schedule_gc_links();
1101 }
1102 up_write(&key->sem);
1103 }
1104}
1105EXPORT_SYMBOL(key_invalidate);
1106
1107/**
1108 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1109 * @key: The key to be instantiated
1110 * @prep: The preparsed data to load.
1111 *
1112 * Instantiate a key from preparsed data. We assume we can just copy the data
1113 * in directly and clear the old pointers.
1114 *
1115 * This can be pointed to directly by the key type instantiate op pointer.
1116 */
1117int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1118{
1119 int ret;
1120
1121 pr_devel("==>%s()\n", __func__);
1122
1123 ret = key_payload_reserve(key, prep->quotalen);
1124 if (ret == 0) {
1125 rcu_assign_keypointer(key, prep->payload.data[0]);
1126 key->payload.data[1] = prep->payload.data[1];
1127 key->payload.data[2] = prep->payload.data[2];
1128 key->payload.data[3] = prep->payload.data[3];
1129 prep->payload.data[0] = NULL;
1130 prep->payload.data[1] = NULL;
1131 prep->payload.data[2] = NULL;
1132 prep->payload.data[3] = NULL;
1133 }
1134 pr_devel("<==%s() = %d\n", __func__, ret);
1135 return ret;
1136}
1137EXPORT_SYMBOL(generic_key_instantiate);
1138
1139/**
1140 * register_key_type - Register a type of key.
1141 * @ktype: The new key type.
1142 *
1143 * Register a new key type.
1144 *
1145 * Returns 0 on success or -EEXIST if a type of this name already exists.
1146 */
1147int register_key_type(struct key_type *ktype)
1148{
1149 struct key_type *p;
1150 int ret;
1151
1152 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1153
1154 ret = -EEXIST;
1155 down_write(&key_types_sem);
1156
1157 /* disallow key types with the same name */
1158 list_for_each_entry(p, &key_types_list, link) {
1159 if (strcmp(p->name, ktype->name) == 0)
1160 goto out;
1161 }
1162
1163 /* store the type */
1164 list_add(&ktype->link, &key_types_list);
1165
1166 pr_notice("Key type %s registered\n", ktype->name);
1167 ret = 0;
1168
1169out:
1170 up_write(&key_types_sem);
1171 return ret;
1172}
1173EXPORT_SYMBOL(register_key_type);
1174
1175/**
1176 * unregister_key_type - Unregister a type of key.
1177 * @ktype: The key type.
1178 *
1179 * Unregister a key type and mark all the extant keys of this type as dead.
1180 * Those keys of this type are then destroyed to get rid of their payloads and
1181 * they and their links will be garbage collected as soon as possible.
1182 */
1183void unregister_key_type(struct key_type *ktype)
1184{
1185 down_write(&key_types_sem);
1186 list_del_init(&ktype->link);
1187 downgrade_write(&key_types_sem);
1188 key_gc_keytype(ktype);
1189 pr_notice("Key type %s unregistered\n", ktype->name);
1190 up_read(&key_types_sem);
1191}
1192EXPORT_SYMBOL(unregister_key_type);
1193
1194/*
1195 * Initialise the key management state.
1196 */
1197void __init key_init(void)
1198{
1199 /* allocate a slab in which we can store keys */
1200 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1201 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1202
1203 /* add the special key types */
1204 list_add_tail(&key_type_keyring.link, &key_types_list);
1205 list_add_tail(&key_type_dead.link, &key_types_list);
1206 list_add_tail(&key_type_user.link, &key_types_list);
1207 list_add_tail(&key_type_logon.link, &key_types_list);
1208
1209 /* record the root user tracking */
1210 rb_link_node(&root_key_user.node,
1211 NULL,
1212 &key_user_tree.rb_node);
1213
1214 rb_insert_color(&root_key_user.node,
1215 &key_user_tree);
1216}
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 unsigned long irqflags;
234
235 key = ERR_PTR(-EINVAL);
236 if (!desc || !*desc)
237 goto error;
238
239 if (type->vet_description) {
240 ret = type->vet_description(desc);
241 if (ret < 0) {
242 key = ERR_PTR(ret);
243 goto error;
244 }
245 }
246
247 desclen = strlen(desc);
248 quotalen = desclen + 1 + type->def_datalen;
249
250 /* get hold of the key tracking for this user */
251 user = key_user_lookup(uid);
252 if (!user)
253 goto no_memory_1;
254
255 /* check that the user's quota permits allocation of another key and
256 * its description */
257 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
258 unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
259 key_quota_root_maxkeys : key_quota_maxkeys;
260 unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
261 key_quota_root_maxbytes : key_quota_maxbytes;
262
263 spin_lock_irqsave(&user->lock, irqflags);
264 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
265 if (user->qnkeys + 1 > maxkeys ||
266 user->qnbytes + quotalen > maxbytes ||
267 user->qnbytes + quotalen < user->qnbytes)
268 goto no_quota;
269 }
270
271 user->qnkeys++;
272 user->qnbytes += quotalen;
273 spin_unlock_irqrestore(&user->lock, irqflags);
274 }
275
276 /* allocate and initialise the key and its description */
277 key = kmem_cache_zalloc(key_jar, GFP_KERNEL);
278 if (!key)
279 goto no_memory_2;
280
281 key->index_key.desc_len = desclen;
282 key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
283 if (!key->index_key.description)
284 goto no_memory_3;
285 key->index_key.type = type;
286 key_set_index_key(&key->index_key);
287
288 refcount_set(&key->usage, 1);
289 init_rwsem(&key->sem);
290 lockdep_set_class(&key->sem, &type->lock_class);
291 key->user = user;
292 key->quotalen = quotalen;
293 key->datalen = type->def_datalen;
294 key->uid = uid;
295 key->gid = gid;
296 key->perm = perm;
297 key->expiry = TIME64_MAX;
298 key->restrict_link = restrict_link;
299 key->last_used_at = ktime_get_real_seconds();
300
301 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
302 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
303 if (flags & KEY_ALLOC_BUILT_IN)
304 key->flags |= 1 << KEY_FLAG_BUILTIN;
305 if (flags & KEY_ALLOC_UID_KEYRING)
306 key->flags |= 1 << KEY_FLAG_UID_KEYRING;
307 if (flags & KEY_ALLOC_SET_KEEP)
308 key->flags |= 1 << KEY_FLAG_KEEP;
309
310#ifdef KEY_DEBUGGING
311 key->magic = KEY_DEBUG_MAGIC;
312#endif
313
314 /* let the security module know about the key */
315 ret = security_key_alloc(key, cred, flags);
316 if (ret < 0)
317 goto security_error;
318
319 /* publish the key by giving it a serial number */
320 refcount_inc(&key->domain_tag->usage);
321 atomic_inc(&user->nkeys);
322 key_alloc_serial(key);
323
324error:
325 return key;
326
327security_error:
328 kfree(key->description);
329 kmem_cache_free(key_jar, key);
330 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
331 spin_lock_irqsave(&user->lock, irqflags);
332 user->qnkeys--;
333 user->qnbytes -= quotalen;
334 spin_unlock_irqrestore(&user->lock, irqflags);
335 }
336 key_user_put(user);
337 key = ERR_PTR(ret);
338 goto error;
339
340no_memory_3:
341 kmem_cache_free(key_jar, key);
342no_memory_2:
343 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
344 spin_lock_irqsave(&user->lock, irqflags);
345 user->qnkeys--;
346 user->qnbytes -= quotalen;
347 spin_unlock_irqrestore(&user->lock, irqflags);
348 }
349 key_user_put(user);
350no_memory_1:
351 key = ERR_PTR(-ENOMEM);
352 goto error;
353
354no_quota:
355 spin_unlock_irqrestore(&user->lock, irqflags);
356 key_user_put(user);
357 key = ERR_PTR(-EDQUOT);
358 goto error;
359}
360EXPORT_SYMBOL(key_alloc);
361
362/**
363 * key_payload_reserve - Adjust data quota reservation for the key's payload
364 * @key: The key to make the reservation for.
365 * @datalen: The amount of data payload the caller now wants.
366 *
367 * Adjust the amount of the owning user's key data quota that a key reserves.
368 * If the amount is increased, then -EDQUOT may be returned if there isn't
369 * enough free quota available.
370 *
371 * If successful, 0 is returned.
372 */
373int key_payload_reserve(struct key *key, size_t datalen)
374{
375 int delta = (int)datalen - key->datalen;
376 int ret = 0;
377
378 key_check(key);
379
380 /* contemplate the quota adjustment */
381 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
382 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
383 key_quota_root_maxbytes : key_quota_maxbytes;
384 unsigned long flags;
385
386 spin_lock_irqsave(&key->user->lock, flags);
387
388 if (delta > 0 &&
389 (key->user->qnbytes + delta > maxbytes ||
390 key->user->qnbytes + delta < key->user->qnbytes)) {
391 ret = -EDQUOT;
392 }
393 else {
394 key->user->qnbytes += delta;
395 key->quotalen += delta;
396 }
397 spin_unlock_irqrestore(&key->user->lock, flags);
398 }
399
400 /* change the recorded data length if that didn't generate an error */
401 if (ret == 0)
402 key->datalen = datalen;
403
404 return ret;
405}
406EXPORT_SYMBOL(key_payload_reserve);
407
408/*
409 * Change the key state to being instantiated.
410 */
411static void mark_key_instantiated(struct key *key, int reject_error)
412{
413 /* Commit the payload before setting the state; barrier versus
414 * key_read_state().
415 */
416 smp_store_release(&key->state,
417 (reject_error < 0) ? reject_error : KEY_IS_POSITIVE);
418}
419
420/*
421 * Instantiate a key and link it into the target keyring atomically. Must be
422 * called with the target keyring's semaphore writelocked. The target key's
423 * semaphore need not be locked as instantiation is serialised by
424 * key_construction_mutex.
425 */
426static int __key_instantiate_and_link(struct key *key,
427 struct key_preparsed_payload *prep,
428 struct key *keyring,
429 struct key *authkey,
430 struct assoc_array_edit **_edit)
431{
432 int ret, awaken;
433
434 key_check(key);
435 key_check(keyring);
436
437 awaken = 0;
438 ret = -EBUSY;
439
440 mutex_lock(&key_construction_mutex);
441
442 /* can't instantiate twice */
443 if (key->state == KEY_IS_UNINSTANTIATED) {
444 /* instantiate the key */
445 ret = key->type->instantiate(key, prep);
446
447 if (ret == 0) {
448 /* mark the key as being instantiated */
449 atomic_inc(&key->user->nikeys);
450 mark_key_instantiated(key, 0);
451 notify_key(key, NOTIFY_KEY_INSTANTIATED, 0);
452
453 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
454 awaken = 1;
455
456 /* and link it into the destination keyring */
457 if (keyring) {
458 if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
459 set_bit(KEY_FLAG_KEEP, &key->flags);
460
461 __key_link(keyring, key, _edit);
462 }
463
464 /* disable the authorisation key */
465 if (authkey)
466 key_invalidate(authkey);
467
468 if (prep->expiry != TIME64_MAX)
469 key_set_expiry(key, prep->expiry);
470 }
471 }
472
473 mutex_unlock(&key_construction_mutex);
474
475 /* wake up anyone waiting for a key to be constructed */
476 if (awaken)
477 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
478
479 return ret;
480}
481
482/**
483 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
484 * @key: The key to instantiate.
485 * @data: The data to use to instantiate the keyring.
486 * @datalen: The length of @data.
487 * @keyring: Keyring to create a link in on success (or NULL).
488 * @authkey: The authorisation token permitting instantiation.
489 *
490 * Instantiate a key that's in the uninstantiated state using the provided data
491 * and, if successful, link it in to the destination keyring if one is
492 * supplied.
493 *
494 * If successful, 0 is returned, the authorisation token is revoked and anyone
495 * waiting for the key is woken up. If the key was already instantiated,
496 * -EBUSY will be returned.
497 */
498int key_instantiate_and_link(struct key *key,
499 const void *data,
500 size_t datalen,
501 struct key *keyring,
502 struct key *authkey)
503{
504 struct key_preparsed_payload prep;
505 struct assoc_array_edit *edit = NULL;
506 int ret;
507
508 memset(&prep, 0, sizeof(prep));
509 prep.orig_description = key->description;
510 prep.data = data;
511 prep.datalen = datalen;
512 prep.quotalen = key->type->def_datalen;
513 prep.expiry = TIME64_MAX;
514 if (key->type->preparse) {
515 ret = key->type->preparse(&prep);
516 if (ret < 0)
517 goto error;
518 }
519
520 if (keyring) {
521 ret = __key_link_lock(keyring, &key->index_key);
522 if (ret < 0)
523 goto error;
524
525 ret = __key_link_begin(keyring, &key->index_key, &edit);
526 if (ret < 0)
527 goto error_link_end;
528
529 if (keyring->restrict_link && keyring->restrict_link->check) {
530 struct key_restriction *keyres = keyring->restrict_link;
531
532 ret = keyres->check(keyring, key->type, &prep.payload,
533 keyres->key);
534 if (ret < 0)
535 goto error_link_end;
536 }
537 }
538
539 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
540
541error_link_end:
542 if (keyring)
543 __key_link_end(keyring, &key->index_key, edit);
544
545error:
546 if (key->type->preparse)
547 key->type->free_preparse(&prep);
548 return ret;
549}
550
551EXPORT_SYMBOL(key_instantiate_and_link);
552
553/**
554 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
555 * @key: The key to instantiate.
556 * @timeout: The timeout on the negative key.
557 * @error: The error to return when the key is hit.
558 * @keyring: Keyring to create a link in on success (or NULL).
559 * @authkey: The authorisation token permitting instantiation.
560 *
561 * Negatively instantiate a key that's in the uninstantiated state and, if
562 * successful, set its timeout and stored error and link it in to the
563 * destination keyring if one is supplied. The key and any links to the key
564 * will be automatically garbage collected after the timeout expires.
565 *
566 * Negative keys are used to rate limit repeated request_key() calls by causing
567 * them to return the stored error code (typically ENOKEY) until the negative
568 * key expires.
569 *
570 * If successful, 0 is returned, the authorisation token is revoked and anyone
571 * waiting for the key is woken up. If the key was already instantiated,
572 * -EBUSY will be returned.
573 */
574int key_reject_and_link(struct key *key,
575 unsigned timeout,
576 unsigned error,
577 struct key *keyring,
578 struct key *authkey)
579{
580 struct assoc_array_edit *edit = NULL;
581 int ret, awaken, link_ret = 0;
582
583 key_check(key);
584 key_check(keyring);
585
586 awaken = 0;
587 ret = -EBUSY;
588
589 if (keyring) {
590 if (keyring->restrict_link)
591 return -EPERM;
592
593 link_ret = __key_link_lock(keyring, &key->index_key);
594 if (link_ret == 0) {
595 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
596 if (link_ret < 0)
597 __key_link_end(keyring, &key->index_key, edit);
598 }
599 }
600
601 mutex_lock(&key_construction_mutex);
602
603 /* can't instantiate twice */
604 if (key->state == KEY_IS_UNINSTANTIATED) {
605 /* mark the key as being negatively instantiated */
606 atomic_inc(&key->user->nikeys);
607 mark_key_instantiated(key, -error);
608 notify_key(key, NOTIFY_KEY_INSTANTIATED, -error);
609 key_set_expiry(key, ktime_get_real_seconds() + timeout);
610
611 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
612 awaken = 1;
613
614 ret = 0;
615
616 /* and link it into the destination keyring */
617 if (keyring && link_ret == 0)
618 __key_link(keyring, key, &edit);
619
620 /* disable the authorisation key */
621 if (authkey)
622 key_invalidate(authkey);
623 }
624
625 mutex_unlock(&key_construction_mutex);
626
627 if (keyring && link_ret == 0)
628 __key_link_end(keyring, &key->index_key, edit);
629
630 /* wake up anyone waiting for a key to be constructed */
631 if (awaken)
632 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
633
634 return ret == 0 ? link_ret : ret;
635}
636EXPORT_SYMBOL(key_reject_and_link);
637
638/**
639 * key_put - Discard a reference to a key.
640 * @key: The key to discard a reference from.
641 *
642 * Discard a reference to a key, and when all the references are gone, we
643 * schedule the cleanup task to come and pull it out of the tree in process
644 * context at some later time.
645 */
646void key_put(struct key *key)
647{
648 if (key) {
649 key_check(key);
650
651 if (refcount_dec_and_test(&key->usage)) {
652 unsigned long flags;
653
654 /* deal with the user's key tracking and quota */
655 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
656 spin_lock_irqsave(&key->user->lock, flags);
657 key->user->qnkeys--;
658 key->user->qnbytes -= key->quotalen;
659 spin_unlock_irqrestore(&key->user->lock, flags);
660 }
661 schedule_work(&key_gc_work);
662 }
663 }
664}
665EXPORT_SYMBOL(key_put);
666
667/*
668 * Find a key by its serial number.
669 */
670struct key *key_lookup(key_serial_t id)
671{
672 struct rb_node *n;
673 struct key *key;
674
675 spin_lock(&key_serial_lock);
676
677 /* search the tree for the specified key */
678 n = key_serial_tree.rb_node;
679 while (n) {
680 key = rb_entry(n, struct key, serial_node);
681
682 if (id < key->serial)
683 n = n->rb_left;
684 else if (id > key->serial)
685 n = n->rb_right;
686 else
687 goto found;
688 }
689
690not_found:
691 key = ERR_PTR(-ENOKEY);
692 goto error;
693
694found:
695 /* A key is allowed to be looked up only if someone still owns a
696 * reference to it - otherwise it's awaiting the gc.
697 */
698 if (!refcount_inc_not_zero(&key->usage))
699 goto not_found;
700
701error:
702 spin_unlock(&key_serial_lock);
703 return key;
704}
705EXPORT_SYMBOL(key_lookup);
706
707/*
708 * Find and lock the specified key type against removal.
709 *
710 * We return with the sem read-locked if successful. If the type wasn't
711 * available -ENOKEY is returned instead.
712 */
713struct key_type *key_type_lookup(const char *type)
714{
715 struct key_type *ktype;
716
717 down_read(&key_types_sem);
718
719 /* look up the key type to see if it's one of the registered kernel
720 * types */
721 list_for_each_entry(ktype, &key_types_list, link) {
722 if (strcmp(ktype->name, type) == 0)
723 goto found_kernel_type;
724 }
725
726 up_read(&key_types_sem);
727 ktype = ERR_PTR(-ENOKEY);
728
729found_kernel_type:
730 return ktype;
731}
732
733void key_set_timeout(struct key *key, unsigned timeout)
734{
735 time64_t expiry = TIME64_MAX;
736
737 /* make the changes with the locks held to prevent races */
738 down_write(&key->sem);
739
740 if (timeout > 0)
741 expiry = ktime_get_real_seconds() + timeout;
742 key_set_expiry(key, expiry);
743
744 up_write(&key->sem);
745}
746EXPORT_SYMBOL_GPL(key_set_timeout);
747
748/*
749 * Unlock a key type locked by key_type_lookup().
750 */
751void key_type_put(struct key_type *ktype)
752{
753 up_read(&key_types_sem);
754}
755
756/*
757 * Attempt to update an existing key.
758 *
759 * The key is given to us with an incremented refcount that we need to discard
760 * if we get an error.
761 */
762static inline key_ref_t __key_update(key_ref_t key_ref,
763 struct key_preparsed_payload *prep)
764{
765 struct key *key = key_ref_to_ptr(key_ref);
766 int ret;
767
768 /* need write permission on the key to update it */
769 ret = key_permission(key_ref, KEY_NEED_WRITE);
770 if (ret < 0)
771 goto error;
772
773 ret = -EEXIST;
774 if (!key->type->update)
775 goto error;
776
777 down_write(&key->sem);
778
779 ret = key->type->update(key, prep);
780 if (ret == 0) {
781 /* Updating a negative key positively instantiates it */
782 mark_key_instantiated(key, 0);
783 notify_key(key, NOTIFY_KEY_UPDATED, 0);
784 }
785
786 up_write(&key->sem);
787
788 if (ret < 0)
789 goto error;
790out:
791 return key_ref;
792
793error:
794 key_put(key);
795 key_ref = ERR_PTR(ret);
796 goto out;
797}
798
799/*
800 * Create or potentially update a key. The combined logic behind
801 * key_create_or_update() and key_create()
802 */
803static key_ref_t __key_create_or_update(key_ref_t keyring_ref,
804 const char *type,
805 const char *description,
806 const void *payload,
807 size_t plen,
808 key_perm_t perm,
809 unsigned long flags,
810 bool allow_update)
811{
812 struct keyring_index_key index_key = {
813 .description = description,
814 };
815 struct key_preparsed_payload prep;
816 struct assoc_array_edit *edit = NULL;
817 const struct cred *cred = current_cred();
818 struct key *keyring, *key = NULL;
819 key_ref_t key_ref;
820 int ret;
821 struct key_restriction *restrict_link = NULL;
822
823 /* look up the key type to see if it's one of the registered kernel
824 * types */
825 index_key.type = key_type_lookup(type);
826 if (IS_ERR(index_key.type)) {
827 key_ref = ERR_PTR(-ENODEV);
828 goto error;
829 }
830
831 key_ref = ERR_PTR(-EINVAL);
832 if (!index_key.type->instantiate ||
833 (!index_key.description && !index_key.type->preparse))
834 goto error_put_type;
835
836 keyring = key_ref_to_ptr(keyring_ref);
837
838 key_check(keyring);
839
840 if (!(flags & KEY_ALLOC_BYPASS_RESTRICTION))
841 restrict_link = keyring->restrict_link;
842
843 key_ref = ERR_PTR(-ENOTDIR);
844 if (keyring->type != &key_type_keyring)
845 goto error_put_type;
846
847 memset(&prep, 0, sizeof(prep));
848 prep.orig_description = description;
849 prep.data = payload;
850 prep.datalen = plen;
851 prep.quotalen = index_key.type->def_datalen;
852 prep.expiry = TIME64_MAX;
853 if (index_key.type->preparse) {
854 ret = index_key.type->preparse(&prep);
855 if (ret < 0) {
856 key_ref = ERR_PTR(ret);
857 goto error_free_prep;
858 }
859 if (!index_key.description)
860 index_key.description = prep.description;
861 key_ref = ERR_PTR(-EINVAL);
862 if (!index_key.description)
863 goto error_free_prep;
864 }
865 index_key.desc_len = strlen(index_key.description);
866 key_set_index_key(&index_key);
867
868 ret = __key_link_lock(keyring, &index_key);
869 if (ret < 0) {
870 key_ref = ERR_PTR(ret);
871 goto error_free_prep;
872 }
873
874 ret = __key_link_begin(keyring, &index_key, &edit);
875 if (ret < 0) {
876 key_ref = ERR_PTR(ret);
877 goto error_link_end;
878 }
879
880 if (restrict_link && restrict_link->check) {
881 ret = restrict_link->check(keyring, index_key.type,
882 &prep.payload, restrict_link->key);
883 if (ret < 0) {
884 key_ref = ERR_PTR(ret);
885 goto error_link_end;
886 }
887 }
888
889 /* if we're going to allocate a new key, we're going to have
890 * to modify the keyring */
891 ret = key_permission(keyring_ref, KEY_NEED_WRITE);
892 if (ret < 0) {
893 key_ref = ERR_PTR(ret);
894 goto error_link_end;
895 }
896
897 /* if it's requested and possible to update this type of key, search
898 * for an existing key of the same type and description in the
899 * destination keyring and update that instead if possible
900 */
901 if (allow_update) {
902 if (index_key.type->update) {
903 key_ref = find_key_to_update(keyring_ref, &index_key);
904 if (key_ref)
905 goto found_matching_key;
906 }
907 } else {
908 key_ref = find_key_to_update(keyring_ref, &index_key);
909 if (key_ref) {
910 key_ref_put(key_ref);
911 key_ref = ERR_PTR(-EEXIST);
912 goto error_link_end;
913 }
914 }
915
916 /* if the client doesn't provide, decide on the permissions we want */
917 if (perm == KEY_PERM_UNDEF) {
918 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
919 perm |= KEY_USR_VIEW;
920
921 if (index_key.type->read)
922 perm |= KEY_POS_READ;
923
924 if (index_key.type == &key_type_keyring ||
925 index_key.type->update)
926 perm |= KEY_POS_WRITE;
927 }
928
929 /* allocate a new key */
930 key = key_alloc(index_key.type, index_key.description,
931 cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
932 if (IS_ERR(key)) {
933 key_ref = ERR_CAST(key);
934 goto error_link_end;
935 }
936
937 /* instantiate it and link it into the target keyring */
938 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
939 if (ret < 0) {
940 key_put(key);
941 key_ref = ERR_PTR(ret);
942 goto error_link_end;
943 }
944
945 security_key_post_create_or_update(keyring, key, payload, plen, flags,
946 true);
947
948 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
949
950error_link_end:
951 __key_link_end(keyring, &index_key, edit);
952error_free_prep:
953 if (index_key.type->preparse)
954 index_key.type->free_preparse(&prep);
955error_put_type:
956 key_type_put(index_key.type);
957error:
958 return key_ref;
959
960 found_matching_key:
961 /* we found a matching key, so we're going to try to update it
962 * - we can drop the locks first as we have the key pinned
963 */
964 __key_link_end(keyring, &index_key, edit);
965
966 key = key_ref_to_ptr(key_ref);
967 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) {
968 ret = wait_for_key_construction(key, true);
969 if (ret < 0) {
970 key_ref_put(key_ref);
971 key_ref = ERR_PTR(ret);
972 goto error_free_prep;
973 }
974 }
975
976 key_ref = __key_update(key_ref, &prep);
977
978 if (!IS_ERR(key_ref))
979 security_key_post_create_or_update(keyring, key, payload, plen,
980 flags, false);
981
982 goto error_free_prep;
983}
984
985/**
986 * key_create_or_update - Update or create and instantiate a key.
987 * @keyring_ref: A pointer to the destination keyring with possession flag.
988 * @type: The type of key.
989 * @description: The searchable description for the key.
990 * @payload: The data to use to instantiate or update the key.
991 * @plen: The length of @payload.
992 * @perm: The permissions mask for a new key.
993 * @flags: The quota flags for a new key.
994 *
995 * Search the destination keyring for a key of the same description and if one
996 * is found, update it, otherwise create and instantiate a new one and create a
997 * link to it from that keyring.
998 *
999 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
1000 * concocted.
1001 *
1002 * Returns a pointer to the new key if successful, -ENODEV if the key type
1003 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
1004 * caller isn't permitted to modify the keyring or the LSM did not permit
1005 * creation of the key.
1006 *
1007 * On success, the possession flag from the keyring ref will be tacked on to
1008 * the key ref before it is returned.
1009 */
1010key_ref_t key_create_or_update(key_ref_t keyring_ref,
1011 const char *type,
1012 const char *description,
1013 const void *payload,
1014 size_t plen,
1015 key_perm_t perm,
1016 unsigned long flags)
1017{
1018 return __key_create_or_update(keyring_ref, type, description, payload,
1019 plen, perm, flags, true);
1020}
1021EXPORT_SYMBOL(key_create_or_update);
1022
1023/**
1024 * key_create - Create and instantiate a key.
1025 * @keyring_ref: A pointer to the destination keyring with possession flag.
1026 * @type: The type of key.
1027 * @description: The searchable description for the key.
1028 * @payload: The data to use to instantiate or update the key.
1029 * @plen: The length of @payload.
1030 * @perm: The permissions mask for a new key.
1031 * @flags: The quota flags for a new key.
1032 *
1033 * Create and instantiate a new key and link to it from the destination keyring.
1034 *
1035 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
1036 * concocted.
1037 *
1038 * Returns a pointer to the new key if successful, -EEXIST if a key with the
1039 * same description already exists, -ENODEV if the key type wasn't available,
1040 * -ENOTDIR if the keyring wasn't a keyring, -EACCES if the caller isn't
1041 * permitted to modify the keyring or the LSM did not permit creation of the
1042 * key.
1043 *
1044 * On success, the possession flag from the keyring ref will be tacked on to
1045 * the key ref before it is returned.
1046 */
1047key_ref_t key_create(key_ref_t keyring_ref,
1048 const char *type,
1049 const char *description,
1050 const void *payload,
1051 size_t plen,
1052 key_perm_t perm,
1053 unsigned long flags)
1054{
1055 return __key_create_or_update(keyring_ref, type, description, payload,
1056 plen, perm, flags, false);
1057}
1058EXPORT_SYMBOL(key_create);
1059
1060/**
1061 * key_update - Update a key's contents.
1062 * @key_ref: The pointer (plus possession flag) to the key.
1063 * @payload: The data to be used to update the key.
1064 * @plen: The length of @payload.
1065 *
1066 * Attempt to update the contents of a key with the given payload data. The
1067 * caller must be granted Write permission on the key. Negative keys can be
1068 * instantiated by this method.
1069 *
1070 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
1071 * type does not support updating. The key type may return other errors.
1072 */
1073int key_update(key_ref_t key_ref, const void *payload, size_t plen)
1074{
1075 struct key_preparsed_payload prep;
1076 struct key *key = key_ref_to_ptr(key_ref);
1077 int ret;
1078
1079 key_check(key);
1080
1081 /* the key must be writable */
1082 ret = key_permission(key_ref, KEY_NEED_WRITE);
1083 if (ret < 0)
1084 return ret;
1085
1086 /* attempt to update it if supported */
1087 if (!key->type->update)
1088 return -EOPNOTSUPP;
1089
1090 memset(&prep, 0, sizeof(prep));
1091 prep.data = payload;
1092 prep.datalen = plen;
1093 prep.quotalen = key->type->def_datalen;
1094 prep.expiry = TIME64_MAX;
1095 if (key->type->preparse) {
1096 ret = key->type->preparse(&prep);
1097 if (ret < 0)
1098 goto error;
1099 }
1100
1101 down_write(&key->sem);
1102
1103 ret = key->type->update(key, &prep);
1104 if (ret == 0) {
1105 /* Updating a negative key positively instantiates it */
1106 mark_key_instantiated(key, 0);
1107 notify_key(key, NOTIFY_KEY_UPDATED, 0);
1108 }
1109
1110 up_write(&key->sem);
1111
1112error:
1113 if (key->type->preparse)
1114 key->type->free_preparse(&prep);
1115 return ret;
1116}
1117EXPORT_SYMBOL(key_update);
1118
1119/**
1120 * key_revoke - Revoke a key.
1121 * @key: The key to be revoked.
1122 *
1123 * Mark a key as being revoked and ask the type to free up its resources. The
1124 * revocation timeout is set and the key and all its links will be
1125 * automatically garbage collected after key_gc_delay amount of time if they
1126 * are not manually dealt with first.
1127 */
1128void key_revoke(struct key *key)
1129{
1130 time64_t time;
1131
1132 key_check(key);
1133
1134 /* make sure no one's trying to change or use the key when we mark it
1135 * - we tell lockdep that we might nest because we might be revoking an
1136 * authorisation key whilst holding the sem on a key we've just
1137 * instantiated
1138 */
1139 down_write_nested(&key->sem, 1);
1140 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags)) {
1141 notify_key(key, NOTIFY_KEY_REVOKED, 0);
1142 if (key->type->revoke)
1143 key->type->revoke(key);
1144
1145 /* set the death time to no more than the expiry time */
1146 time = ktime_get_real_seconds();
1147 if (key->revoked_at == 0 || key->revoked_at > time) {
1148 key->revoked_at = time;
1149 key_schedule_gc(key->revoked_at + key_gc_delay);
1150 }
1151 }
1152
1153 up_write(&key->sem);
1154}
1155EXPORT_SYMBOL(key_revoke);
1156
1157/**
1158 * key_invalidate - Invalidate a key.
1159 * @key: The key to be invalidated.
1160 *
1161 * Mark a key as being invalidated and have it cleaned up immediately. The key
1162 * is ignored by all searches and other operations from this point.
1163 */
1164void key_invalidate(struct key *key)
1165{
1166 kenter("%d", key_serial(key));
1167
1168 key_check(key);
1169
1170 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1171 down_write_nested(&key->sem, 1);
1172 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1173 notify_key(key, NOTIFY_KEY_INVALIDATED, 0);
1174 key_schedule_gc_links();
1175 }
1176 up_write(&key->sem);
1177 }
1178}
1179EXPORT_SYMBOL(key_invalidate);
1180
1181/**
1182 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1183 * @key: The key to be instantiated
1184 * @prep: The preparsed data to load.
1185 *
1186 * Instantiate a key from preparsed data. We assume we can just copy the data
1187 * in directly and clear the old pointers.
1188 *
1189 * This can be pointed to directly by the key type instantiate op pointer.
1190 */
1191int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1192{
1193 int ret;
1194
1195 pr_devel("==>%s()\n", __func__);
1196
1197 ret = key_payload_reserve(key, prep->quotalen);
1198 if (ret == 0) {
1199 rcu_assign_keypointer(key, prep->payload.data[0]);
1200 key->payload.data[1] = prep->payload.data[1];
1201 key->payload.data[2] = prep->payload.data[2];
1202 key->payload.data[3] = prep->payload.data[3];
1203 prep->payload.data[0] = NULL;
1204 prep->payload.data[1] = NULL;
1205 prep->payload.data[2] = NULL;
1206 prep->payload.data[3] = NULL;
1207 }
1208 pr_devel("<==%s() = %d\n", __func__, ret);
1209 return ret;
1210}
1211EXPORT_SYMBOL(generic_key_instantiate);
1212
1213/**
1214 * register_key_type - Register a type of key.
1215 * @ktype: The new key type.
1216 *
1217 * Register a new key type.
1218 *
1219 * Returns 0 on success or -EEXIST if a type of this name already exists.
1220 */
1221int register_key_type(struct key_type *ktype)
1222{
1223 struct key_type *p;
1224 int ret;
1225
1226 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1227
1228 ret = -EEXIST;
1229 down_write(&key_types_sem);
1230
1231 /* disallow key types with the same name */
1232 list_for_each_entry(p, &key_types_list, link) {
1233 if (strcmp(p->name, ktype->name) == 0)
1234 goto out;
1235 }
1236
1237 /* store the type */
1238 list_add(&ktype->link, &key_types_list);
1239
1240 pr_notice("Key type %s registered\n", ktype->name);
1241 ret = 0;
1242
1243out:
1244 up_write(&key_types_sem);
1245 return ret;
1246}
1247EXPORT_SYMBOL(register_key_type);
1248
1249/**
1250 * unregister_key_type - Unregister a type of key.
1251 * @ktype: The key type.
1252 *
1253 * Unregister a key type and mark all the extant keys of this type as dead.
1254 * Those keys of this type are then destroyed to get rid of their payloads and
1255 * they and their links will be garbage collected as soon as possible.
1256 */
1257void unregister_key_type(struct key_type *ktype)
1258{
1259 down_write(&key_types_sem);
1260 list_del_init(&ktype->link);
1261 downgrade_write(&key_types_sem);
1262 key_gc_keytype(ktype);
1263 pr_notice("Key type %s unregistered\n", ktype->name);
1264 up_read(&key_types_sem);
1265}
1266EXPORT_SYMBOL(unregister_key_type);
1267
1268/*
1269 * Initialise the key management state.
1270 */
1271void __init key_init(void)
1272{
1273 /* allocate a slab in which we can store keys */
1274 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1275 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1276
1277 /* add the special key types */
1278 list_add_tail(&key_type_keyring.link, &key_types_list);
1279 list_add_tail(&key_type_dead.link, &key_types_list);
1280 list_add_tail(&key_type_user.link, &key_types_list);
1281 list_add_tail(&key_type_logon.link, &key_types_list);
1282
1283 /* record the root user tracking */
1284 rb_link_node(&root_key_user.node,
1285 NULL,
1286 &key_user_tree.rb_node);
1287
1288 rb_insert_color(&root_key_user.node,
1289 &key_user_tree);
1290}