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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 ([email protected])
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_obj(struct key_user);
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 key->flags |= 1 << KEY_FLAG_USER_ALIVE;
302 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
303 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
304 if (flags & KEY_ALLOC_BUILT_IN)
305 key->flags |= 1 << KEY_FLAG_BUILTIN;
306 if (flags & KEY_ALLOC_UID_KEYRING)
307 key->flags |= 1 << KEY_FLAG_UID_KEYRING;
308 if (flags & KEY_ALLOC_SET_KEEP)
309 key->flags |= 1 << KEY_FLAG_KEEP;
310
311#ifdef KEY_DEBUGGING
312 key->magic = KEY_DEBUG_MAGIC;
313#endif
314
315 /* let the security module know about the key */
316 ret = security_key_alloc(key, cred, flags);
317 if (ret < 0)
318 goto security_error;
319
320 /* publish the key by giving it a serial number */
321 refcount_inc(&key->domain_tag->usage);
322 atomic_inc(&user->nkeys);
323 key_alloc_serial(key);
324
325error:
326 return key;
327
328security_error:
329 kfree(key->description);
330 kmem_cache_free(key_jar, key);
331 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
332 spin_lock_irqsave(&user->lock, irqflags);
333 user->qnkeys--;
334 user->qnbytes -= quotalen;
335 spin_unlock_irqrestore(&user->lock, irqflags);
336 }
337 key_user_put(user);
338 key = ERR_PTR(ret);
339 goto error;
340
341no_memory_3:
342 kmem_cache_free(key_jar, key);
343no_memory_2:
344 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
345 spin_lock_irqsave(&user->lock, irqflags);
346 user->qnkeys--;
347 user->qnbytes -= quotalen;
348 spin_unlock_irqrestore(&user->lock, irqflags);
349 }
350 key_user_put(user);
351no_memory_1:
352 key = ERR_PTR(-ENOMEM);
353 goto error;
354
355no_quota:
356 spin_unlock_irqrestore(&user->lock, irqflags);
357 key_user_put(user);
358 key = ERR_PTR(-EDQUOT);
359 goto error;
360}
361EXPORT_SYMBOL(key_alloc);
362
363/**
364 * key_payload_reserve - Adjust data quota reservation for the key's payload
365 * @key: The key to make the reservation for.
366 * @datalen: The amount of data payload the caller now wants.
367 *
368 * Adjust the amount of the owning user's key data quota that a key reserves.
369 * If the amount is increased, then -EDQUOT may be returned if there isn't
370 * enough free quota available.
371 *
372 * If successful, 0 is returned.
373 */
374int key_payload_reserve(struct key *key, size_t datalen)
375{
376 int delta = (int)datalen - key->datalen;
377 int ret = 0;
378
379 key_check(key);
380
381 /* contemplate the quota adjustment */
382 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
383 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
384 key_quota_root_maxbytes : key_quota_maxbytes;
385 unsigned long flags;
386
387 spin_lock_irqsave(&key->user->lock, flags);
388
389 if (delta > 0 &&
390 (key->user->qnbytes + delta > maxbytes ||
391 key->user->qnbytes + delta < key->user->qnbytes)) {
392 ret = -EDQUOT;
393 }
394 else {
395 key->user->qnbytes += delta;
396 key->quotalen += delta;
397 }
398 spin_unlock_irqrestore(&key->user->lock, flags);
399 }
400
401 /* change the recorded data length if that didn't generate an error */
402 if (ret == 0)
403 key->datalen = datalen;
404
405 return ret;
406}
407EXPORT_SYMBOL(key_payload_reserve);
408
409/*
410 * Change the key state to being instantiated.
411 */
412static void mark_key_instantiated(struct key *key, int reject_error)
413{
414 /* Commit the payload before setting the state; barrier versus
415 * key_read_state().
416 */
417 smp_store_release(&key->state,
418 (reject_error < 0) ? reject_error : KEY_IS_POSITIVE);
419}
420
421/*
422 * Instantiate a key and link it into the target keyring atomically. Must be
423 * called with the target keyring's semaphore writelocked. The target key's
424 * semaphore need not be locked as instantiation is serialised by
425 * key_construction_mutex.
426 */
427static int __key_instantiate_and_link(struct key *key,
428 struct key_preparsed_payload *prep,
429 struct key *keyring,
430 struct key *authkey,
431 struct assoc_array_edit **_edit)
432{
433 int ret, awaken;
434
435 key_check(key);
436 key_check(keyring);
437
438 awaken = 0;
439 ret = -EBUSY;
440
441 mutex_lock(&key_construction_mutex);
442
443 /* can't instantiate twice */
444 if (key->state == KEY_IS_UNINSTANTIATED) {
445 /* instantiate the key */
446 ret = key->type->instantiate(key, prep);
447
448 if (ret == 0) {
449 /* mark the key as being instantiated */
450 atomic_inc(&key->user->nikeys);
451 mark_key_instantiated(key, 0);
452 notify_key(key, NOTIFY_KEY_INSTANTIATED, 0);
453
454 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
455 awaken = 1;
456
457 /* and link it into the destination keyring */
458 if (keyring) {
459 if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
460 set_bit(KEY_FLAG_KEEP, &key->flags);
461
462 __key_link(keyring, key, _edit);
463 }
464
465 /* disable the authorisation key */
466 if (authkey)
467 key_invalidate(authkey);
468
469 if (prep->expiry != TIME64_MAX)
470 key_set_expiry(key, prep->expiry);
471 }
472 }
473
474 mutex_unlock(&key_construction_mutex);
475
476 /* wake up anyone waiting for a key to be constructed */
477 if (awaken)
478 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
479
480 return ret;
481}
482
483/**
484 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
485 * @key: The key to instantiate.
486 * @data: The data to use to instantiate the keyring.
487 * @datalen: The length of @data.
488 * @keyring: Keyring to create a link in on success (or NULL).
489 * @authkey: The authorisation token permitting instantiation.
490 *
491 * Instantiate a key that's in the uninstantiated state using the provided data
492 * and, if successful, link it in to the destination keyring if one is
493 * supplied.
494 *
495 * If successful, 0 is returned, the authorisation token is revoked and anyone
496 * waiting for the key is woken up. If the key was already instantiated,
497 * -EBUSY will be returned.
498 */
499int key_instantiate_and_link(struct key *key,
500 const void *data,
501 size_t datalen,
502 struct key *keyring,
503 struct key *authkey)
504{
505 struct key_preparsed_payload prep;
506 struct assoc_array_edit *edit = NULL;
507 int ret;
508
509 memset(&prep, 0, sizeof(prep));
510 prep.orig_description = key->description;
511 prep.data = data;
512 prep.datalen = datalen;
513 prep.quotalen = key->type->def_datalen;
514 prep.expiry = TIME64_MAX;
515 if (key->type->preparse) {
516 ret = key->type->preparse(&prep);
517 if (ret < 0)
518 goto error;
519 }
520
521 if (keyring) {
522 ret = __key_link_lock(keyring, &key->index_key);
523 if (ret < 0)
524 goto error;
525
526 ret = __key_link_begin(keyring, &key->index_key, &edit);
527 if (ret < 0)
528 goto error_link_end;
529
530 if (keyring->restrict_link && keyring->restrict_link->check) {
531 struct key_restriction *keyres = keyring->restrict_link;
532
533 ret = keyres->check(keyring, key->type, &prep.payload,
534 keyres->key);
535 if (ret < 0)
536 goto error_link_end;
537 }
538 }
539
540 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
541
542error_link_end:
543 if (keyring)
544 __key_link_end(keyring, &key->index_key, edit);
545
546error:
547 if (key->type->preparse)
548 key->type->free_preparse(&prep);
549 return ret;
550}
551
552EXPORT_SYMBOL(key_instantiate_and_link);
553
554/**
555 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
556 * @key: The key to instantiate.
557 * @timeout: The timeout on the negative key.
558 * @error: The error to return when the key is hit.
559 * @keyring: Keyring to create a link in on success (or NULL).
560 * @authkey: The authorisation token permitting instantiation.
561 *
562 * Negatively instantiate a key that's in the uninstantiated state and, if
563 * successful, set its timeout and stored error and link it in to the
564 * destination keyring if one is supplied. The key and any links to the key
565 * will be automatically garbage collected after the timeout expires.
566 *
567 * Negative keys are used to rate limit repeated request_key() calls by causing
568 * them to return the stored error code (typically ENOKEY) until the negative
569 * key expires.
570 *
571 * If successful, 0 is returned, the authorisation token is revoked and anyone
572 * waiting for the key is woken up. If the key was already instantiated,
573 * -EBUSY will be returned.
574 */
575int key_reject_and_link(struct key *key,
576 unsigned timeout,
577 unsigned error,
578 struct key *keyring,
579 struct key *authkey)
580{
581 struct assoc_array_edit *edit = NULL;
582 int ret, awaken, link_ret = 0;
583
584 key_check(key);
585 key_check(keyring);
586
587 awaken = 0;
588 ret = -EBUSY;
589
590 if (keyring) {
591 if (keyring->restrict_link)
592 return -EPERM;
593
594 link_ret = __key_link_lock(keyring, &key->index_key);
595 if (link_ret == 0) {
596 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
597 if (link_ret < 0)
598 __key_link_end(keyring, &key->index_key, edit);
599 }
600 }
601
602 mutex_lock(&key_construction_mutex);
603
604 /* can't instantiate twice */
605 if (key->state == KEY_IS_UNINSTANTIATED) {
606 /* mark the key as being negatively instantiated */
607 atomic_inc(&key->user->nikeys);
608 mark_key_instantiated(key, -error);
609 notify_key(key, NOTIFY_KEY_INSTANTIATED, -error);
610 key_set_expiry(key, ktime_get_real_seconds() + timeout);
611
612 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
613 awaken = 1;
614
615 ret = 0;
616
617 /* and link it into the destination keyring */
618 if (keyring && link_ret == 0)
619 __key_link(keyring, key, &edit);
620
621 /* disable the authorisation key */
622 if (authkey)
623 key_invalidate(authkey);
624 }
625
626 mutex_unlock(&key_construction_mutex);
627
628 if (keyring && link_ret == 0)
629 __key_link_end(keyring, &key->index_key, edit);
630
631 /* wake up anyone waiting for a key to be constructed */
632 if (awaken)
633 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
634
635 return ret == 0 ? link_ret : ret;
636}
637EXPORT_SYMBOL(key_reject_and_link);
638
639/**
640 * key_put - Discard a reference to a key.
641 * @key: The key to discard a reference from.
642 *
643 * Discard a reference to a key, and when all the references are gone, we
644 * schedule the cleanup task to come and pull it out of the tree in process
645 * context at some later time.
646 */
647void key_put(struct key *key)
648{
649 if (key) {
650 key_check(key);
651
652 if (refcount_dec_and_test(&key->usage)) {
653 unsigned long flags;
654
655 /* deal with the user's key tracking and quota */
656 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
657 spin_lock_irqsave(&key->user->lock, flags);
658 key->user->qnkeys--;
659 key->user->qnbytes -= key->quotalen;
660 spin_unlock_irqrestore(&key->user->lock, flags);
661 }
662 /* Mark key as safe for GC after key->user done. */
663 clear_bit_unlock(KEY_FLAG_USER_ALIVE, &key->flags);
664 schedule_work(&key_gc_work);
665 }
666 }
667}
668EXPORT_SYMBOL(key_put);
669
670/*
671 * Find a key by its serial number.
672 */
673struct key *key_lookup(key_serial_t id)
674{
675 struct rb_node *n;
676 struct key *key;
677
678 spin_lock(&key_serial_lock);
679
680 /* search the tree for the specified key */
681 n = key_serial_tree.rb_node;
682 while (n) {
683 key = rb_entry(n, struct key, serial_node);
684
685 if (id < key->serial)
686 n = n->rb_left;
687 else if (id > key->serial)
688 n = n->rb_right;
689 else
690 goto found;
691 }
692
693not_found:
694 key = ERR_PTR(-ENOKEY);
695 goto error;
696
697found:
698 /* A key is allowed to be looked up only if someone still owns a
699 * reference to it - otherwise it's awaiting the gc.
700 */
701 if (!refcount_inc_not_zero(&key->usage))
702 goto not_found;
703
704error:
705 spin_unlock(&key_serial_lock);
706 return key;
707}
708EXPORT_SYMBOL(key_lookup);
709
710/*
711 * Find and lock the specified key type against removal.
712 *
713 * We return with the sem read-locked if successful. If the type wasn't
714 * available -ENOKEY is returned instead.
715 */
716struct key_type *key_type_lookup(const char *type)
717{
718 struct key_type *ktype;
719
720 down_read(&key_types_sem);
721
722 /* look up the key type to see if it's one of the registered kernel
723 * types */
724 list_for_each_entry(ktype, &key_types_list, link) {
725 if (strcmp(ktype->name, type) == 0)
726 goto found_kernel_type;
727 }
728
729 up_read(&key_types_sem);
730 ktype = ERR_PTR(-ENOKEY);
731
732found_kernel_type:
733 return ktype;
734}
735
736void key_set_timeout(struct key *key, unsigned timeout)
737{
738 time64_t expiry = TIME64_MAX;
739
740 /* make the changes with the locks held to prevent races */
741 down_write(&key->sem);
742
743 if (timeout > 0)
744 expiry = ktime_get_real_seconds() + timeout;
745 key_set_expiry(key, expiry);
746
747 up_write(&key->sem);
748}
749EXPORT_SYMBOL_GPL(key_set_timeout);
750
751/*
752 * Unlock a key type locked by key_type_lookup().
753 */
754void key_type_put(struct key_type *ktype)
755{
756 up_read(&key_types_sem);
757}
758
759/*
760 * Attempt to update an existing key.
761 *
762 * The key is given to us with an incremented refcount that we need to discard
763 * if we get an error.
764 */
765static inline key_ref_t __key_update(key_ref_t key_ref,
766 struct key_preparsed_payload *prep)
767{
768 struct key *key = key_ref_to_ptr(key_ref);
769 int ret;
770
771 /* need write permission on the key to update it */
772 ret = key_permission(key_ref, KEY_NEED_WRITE);
773 if (ret < 0)
774 goto error;
775
776 ret = -EEXIST;
777 if (!key->type->update)
778 goto error;
779
780 down_write(&key->sem);
781
782 ret = key->type->update(key, prep);
783 if (ret == 0) {
784 /* Updating a negative key positively instantiates it */
785 mark_key_instantiated(key, 0);
786 notify_key(key, NOTIFY_KEY_UPDATED, 0);
787 }
788
789 up_write(&key->sem);
790
791 if (ret < 0)
792 goto error;
793out:
794 return key_ref;
795
796error:
797 key_put(key);
798 key_ref = ERR_PTR(ret);
799 goto out;
800}
801
802/*
803 * Create or potentially update a key. The combined logic behind
804 * key_create_or_update() and key_create()
805 */
806static key_ref_t __key_create_or_update(key_ref_t keyring_ref,
807 const char *type,
808 const char *description,
809 const void *payload,
810 size_t plen,
811 key_perm_t perm,
812 unsigned long flags,
813 bool allow_update)
814{
815 struct keyring_index_key index_key = {
816 .description = description,
817 };
818 struct key_preparsed_payload prep;
819 struct assoc_array_edit *edit = NULL;
820 const struct cred *cred = current_cred();
821 struct key *keyring, *key = NULL;
822 key_ref_t key_ref;
823 int ret;
824 struct key_restriction *restrict_link = NULL;
825
826 /* look up the key type to see if it's one of the registered kernel
827 * types */
828 index_key.type = key_type_lookup(type);
829 if (IS_ERR(index_key.type)) {
830 key_ref = ERR_PTR(-ENODEV);
831 goto error;
832 }
833
834 key_ref = ERR_PTR(-EINVAL);
835 if (!index_key.type->instantiate ||
836 (!index_key.description && !index_key.type->preparse))
837 goto error_put_type;
838
839 keyring = key_ref_to_ptr(keyring_ref);
840
841 key_check(keyring);
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 (!(flags & KEY_ALLOC_BYPASS_RESTRICTION))
881 restrict_link = keyring->restrict_link;
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 requested and possible to update this type of key, search
901 * for an existing key of the same type and description in the
902 * destination keyring and update that instead if possible
903 */
904 if (allow_update) {
905 if (index_key.type->update) {
906 key_ref = find_key_to_update(keyring_ref, &index_key);
907 if (key_ref)
908 goto found_matching_key;
909 }
910 } else {
911 key_ref = find_key_to_update(keyring_ref, &index_key);
912 if (key_ref) {
913 key_ref_put(key_ref);
914 key_ref = ERR_PTR(-EEXIST);
915 goto error_link_end;
916 }
917 }
918
919 /* if the client doesn't provide, decide on the permissions we want */
920 if (perm == KEY_PERM_UNDEF) {
921 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
922 perm |= KEY_USR_VIEW;
923
924 if (index_key.type->read)
925 perm |= KEY_POS_READ;
926
927 if (index_key.type == &key_type_keyring ||
928 index_key.type->update)
929 perm |= KEY_POS_WRITE;
930 }
931
932 /* allocate a new key */
933 key = key_alloc(index_key.type, index_key.description,
934 cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
935 if (IS_ERR(key)) {
936 key_ref = ERR_CAST(key);
937 goto error_link_end;
938 }
939
940 /* instantiate it and link it into the target keyring */
941 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
942 if (ret < 0) {
943 key_put(key);
944 key_ref = ERR_PTR(ret);
945 goto error_link_end;
946 }
947
948 security_key_post_create_or_update(keyring, key, payload, plen, flags,
949 true);
950
951 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
952
953error_link_end:
954 __key_link_end(keyring, &index_key, edit);
955error_free_prep:
956 if (index_key.type->preparse)
957 index_key.type->free_preparse(&prep);
958error_put_type:
959 key_type_put(index_key.type);
960error:
961 return key_ref;
962
963 found_matching_key:
964 /* we found a matching key, so we're going to try to update it
965 * - we can drop the locks first as we have the key pinned
966 */
967 __key_link_end(keyring, &index_key, edit);
968
969 key = key_ref_to_ptr(key_ref);
970 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) {
971 ret = wait_for_key_construction(key, true);
972 if (ret < 0) {
973 key_ref_put(key_ref);
974 key_ref = ERR_PTR(ret);
975 goto error_free_prep;
976 }
977 }
978
979 key_ref = __key_update(key_ref, &prep);
980
981 if (!IS_ERR(key_ref))
982 security_key_post_create_or_update(keyring, key, payload, plen,
983 flags, false);
984
985 goto error_free_prep;
986}
987
988/**
989 * key_create_or_update - Update or create and instantiate a key.
990 * @keyring_ref: A pointer to the destination keyring with possession flag.
991 * @type: The type of key.
992 * @description: The searchable description for the key.
993 * @payload: The data to use to instantiate or update the key.
994 * @plen: The length of @payload.
995 * @perm: The permissions mask for a new key.
996 * @flags: The quota flags for a new key.
997 *
998 * Search the destination keyring for a key of the same description and if one
999 * is found, update it, otherwise create and instantiate a new one and create a
1000 * link to it from that keyring.
1001 *
1002 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
1003 * concocted.
1004 *
1005 * Returns a pointer to the new key if successful, -ENODEV if the key type
1006 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
1007 * caller isn't permitted to modify the keyring or the LSM did not permit
1008 * creation of the key.
1009 *
1010 * On success, the possession flag from the keyring ref will be tacked on to
1011 * the key ref before it is returned.
1012 */
1013key_ref_t key_create_or_update(key_ref_t keyring_ref,
1014 const char *type,
1015 const char *description,
1016 const void *payload,
1017 size_t plen,
1018 key_perm_t perm,
1019 unsigned long flags)
1020{
1021 return __key_create_or_update(keyring_ref, type, description, payload,
1022 plen, perm, flags, true);
1023}
1024EXPORT_SYMBOL(key_create_or_update);
1025
1026/**
1027 * key_create - Create and instantiate a key.
1028 * @keyring_ref: A pointer to the destination keyring with possession flag.
1029 * @type: The type of key.
1030 * @description: The searchable description for the key.
1031 * @payload: The data to use to instantiate or update the key.
1032 * @plen: The length of @payload.
1033 * @perm: The permissions mask for a new key.
1034 * @flags: The quota flags for a new key.
1035 *
1036 * Create and instantiate a new key and link to it from the destination keyring.
1037 *
1038 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
1039 * concocted.
1040 *
1041 * Returns a pointer to the new key if successful, -EEXIST if a key with the
1042 * same description already exists, -ENODEV if the key type wasn't available,
1043 * -ENOTDIR if the keyring wasn't a keyring, -EACCES if the caller isn't
1044 * permitted to modify the keyring or the LSM did not permit creation of the
1045 * key.
1046 *
1047 * On success, the possession flag from the keyring ref will be tacked on to
1048 * the key ref before it is returned.
1049 */
1050key_ref_t key_create(key_ref_t keyring_ref,
1051 const char *type,
1052 const char *description,
1053 const void *payload,
1054 size_t plen,
1055 key_perm_t perm,
1056 unsigned long flags)
1057{
1058 return __key_create_or_update(keyring_ref, type, description, payload,
1059 plen, perm, flags, false);
1060}
1061EXPORT_SYMBOL(key_create);
1062
1063/**
1064 * key_update - Update a key's contents.
1065 * @key_ref: The pointer (plus possession flag) to the key.
1066 * @payload: The data to be used to update the key.
1067 * @plen: The length of @payload.
1068 *
1069 * Attempt to update the contents of a key with the given payload data. The
1070 * caller must be granted Write permission on the key. Negative keys can be
1071 * instantiated by this method.
1072 *
1073 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
1074 * type does not support updating. The key type may return other errors.
1075 */
1076int key_update(key_ref_t key_ref, const void *payload, size_t plen)
1077{
1078 struct key_preparsed_payload prep;
1079 struct key *key = key_ref_to_ptr(key_ref);
1080 int ret;
1081
1082 key_check(key);
1083
1084 /* the key must be writable */
1085 ret = key_permission(key_ref, KEY_NEED_WRITE);
1086 if (ret < 0)
1087 return ret;
1088
1089 /* attempt to update it if supported */
1090 if (!key->type->update)
1091 return -EOPNOTSUPP;
1092
1093 memset(&prep, 0, sizeof(prep));
1094 prep.data = payload;
1095 prep.datalen = plen;
1096 prep.quotalen = key->type->def_datalen;
1097 prep.expiry = TIME64_MAX;
1098 if (key->type->preparse) {
1099 ret = key->type->preparse(&prep);
1100 if (ret < 0)
1101 goto error;
1102 }
1103
1104 down_write(&key->sem);
1105
1106 ret = key->type->update(key, &prep);
1107 if (ret == 0) {
1108 /* Updating a negative key positively instantiates it */
1109 mark_key_instantiated(key, 0);
1110 notify_key(key, NOTIFY_KEY_UPDATED, 0);
1111 }
1112
1113 up_write(&key->sem);
1114
1115error:
1116 if (key->type->preparse)
1117 key->type->free_preparse(&prep);
1118 return ret;
1119}
1120EXPORT_SYMBOL(key_update);
1121
1122/**
1123 * key_revoke - Revoke a key.
1124 * @key: The key to be revoked.
1125 *
1126 * Mark a key as being revoked and ask the type to free up its resources. The
1127 * revocation timeout is set and the key and all its links will be
1128 * automatically garbage collected after key_gc_delay amount of time if they
1129 * are not manually dealt with first.
1130 */
1131void key_revoke(struct key *key)
1132{
1133 time64_t time;
1134
1135 key_check(key);
1136
1137 /* make sure no one's trying to change or use the key when we mark it
1138 * - we tell lockdep that we might nest because we might be revoking an
1139 * authorisation key whilst holding the sem on a key we've just
1140 * instantiated
1141 */
1142 down_write_nested(&key->sem, 1);
1143 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags)) {
1144 notify_key(key, NOTIFY_KEY_REVOKED, 0);
1145 if (key->type->revoke)
1146 key->type->revoke(key);
1147
1148 /* set the death time to no more than the expiry time */
1149 time = ktime_get_real_seconds();
1150 if (key->revoked_at == 0 || key->revoked_at > time) {
1151 key->revoked_at = time;
1152 key_schedule_gc(key->revoked_at + key_gc_delay);
1153 }
1154 }
1155
1156 up_write(&key->sem);
1157}
1158EXPORT_SYMBOL(key_revoke);
1159
1160/**
1161 * key_invalidate - Invalidate a key.
1162 * @key: The key to be invalidated.
1163 *
1164 * Mark a key as being invalidated and have it cleaned up immediately. The key
1165 * is ignored by all searches and other operations from this point.
1166 */
1167void key_invalidate(struct key *key)
1168{
1169 kenter("%d", key_serial(key));
1170
1171 key_check(key);
1172
1173 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1174 down_write_nested(&key->sem, 1);
1175 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1176 notify_key(key, NOTIFY_KEY_INVALIDATED, 0);
1177 key_schedule_gc_links();
1178 }
1179 up_write(&key->sem);
1180 }
1181}
1182EXPORT_SYMBOL(key_invalidate);
1183
1184/**
1185 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1186 * @key: The key to be instantiated
1187 * @prep: The preparsed data to load.
1188 *
1189 * Instantiate a key from preparsed data. We assume we can just copy the data
1190 * in directly and clear the old pointers.
1191 *
1192 * This can be pointed to directly by the key type instantiate op pointer.
1193 */
1194int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1195{
1196 int ret;
1197
1198 pr_devel("==>%s()\n", __func__);
1199
1200 ret = key_payload_reserve(key, prep->quotalen);
1201 if (ret == 0) {
1202 rcu_assign_keypointer(key, prep->payload.data[0]);
1203 key->payload.data[1] = prep->payload.data[1];
1204 key->payload.data[2] = prep->payload.data[2];
1205 key->payload.data[3] = prep->payload.data[3];
1206 prep->payload.data[0] = NULL;
1207 prep->payload.data[1] = NULL;
1208 prep->payload.data[2] = NULL;
1209 prep->payload.data[3] = NULL;
1210 }
1211 pr_devel("<==%s() = %d\n", __func__, ret);
1212 return ret;
1213}
1214EXPORT_SYMBOL(generic_key_instantiate);
1215
1216/**
1217 * register_key_type - Register a type of key.
1218 * @ktype: The new key type.
1219 *
1220 * Register a new key type.
1221 *
1222 * Returns 0 on success or -EEXIST if a type of this name already exists.
1223 */
1224int register_key_type(struct key_type *ktype)
1225{
1226 struct key_type *p;
1227 int ret;
1228
1229 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1230
1231 ret = -EEXIST;
1232 down_write(&key_types_sem);
1233
1234 /* disallow key types with the same name */
1235 list_for_each_entry(p, &key_types_list, link) {
1236 if (strcmp(p->name, ktype->name) == 0)
1237 goto out;
1238 }
1239
1240 /* store the type */
1241 list_add(&ktype->link, &key_types_list);
1242
1243 pr_notice("Key type %s registered\n", ktype->name);
1244 ret = 0;
1245
1246out:
1247 up_write(&key_types_sem);
1248 return ret;
1249}
1250EXPORT_SYMBOL(register_key_type);
1251
1252/**
1253 * unregister_key_type - Unregister a type of key.
1254 * @ktype: The key type.
1255 *
1256 * Unregister a key type and mark all the extant keys of this type as dead.
1257 * Those keys of this type are then destroyed to get rid of their payloads and
1258 * they and their links will be garbage collected as soon as possible.
1259 */
1260void unregister_key_type(struct key_type *ktype)
1261{
1262 down_write(&key_types_sem);
1263 list_del_init(&ktype->link);
1264 downgrade_write(&key_types_sem);
1265 key_gc_keytype(ktype);
1266 pr_notice("Key type %s unregistered\n", ktype->name);
1267 up_read(&key_types_sem);
1268}
1269EXPORT_SYMBOL(unregister_key_type);
1270
1271/*
1272 * Initialise the key management state.
1273 */
1274void __init key_init(void)
1275{
1276 /* allocate a slab in which we can store keys */
1277 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1278 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_NO_MERGE, NULL);
1279
1280 /* add the special key types */
1281 list_add_tail(&key_type_keyring.link, &key_types_list);
1282 list_add_tail(&key_type_dead.link, &key_types_list);
1283 list_add_tail(&key_type_user.link, &key_types_list);
1284 list_add_tail(&key_type_logon.link, &key_types_list);
1285
1286 /* record the root user tracking */
1287 rb_link_node(&root_key_user.node,
1288 NULL,
1289 &key_user_tree.rb_node);
1290
1291 rb_insert_color(&root_key_user.node,
1292 &key_user_tree);
1293}