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1/* Basic authentication token and access key management
2 *
3 * Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/poison.h>
15#include <linux/sched.h>
16#include <linux/slab.h>
17#include <linux/security.h>
18#include <linux/workqueue.h>
19#include <linux/random.h>
20#include <linux/err.h>
21#include "internal.h"
22
23struct kmem_cache *key_jar;
24struct rb_root key_serial_tree; /* tree of keys indexed by serial */
25DEFINE_SPINLOCK(key_serial_lock);
26
27struct rb_root key_user_tree; /* tree of quota records indexed by UID */
28DEFINE_SPINLOCK(key_user_lock);
29
30unsigned int key_quota_root_maxkeys = 200; /* root's key count quota */
31unsigned int key_quota_root_maxbytes = 20000; /* root's key space quota */
32unsigned int key_quota_maxkeys = 200; /* general key count quota */
33unsigned int key_quota_maxbytes = 20000; /* general key space quota */
34
35static LIST_HEAD(key_types_list);
36static DECLARE_RWSEM(key_types_sem);
37
38/* We serialise key instantiation and link */
39DEFINE_MUTEX(key_construction_mutex);
40
41#ifdef KEY_DEBUGGING
42void __key_check(const struct key *key)
43{
44 printk("__key_check: key %p {%08x} should be {%08x}\n",
45 key, key->magic, KEY_DEBUG_MAGIC);
46 BUG();
47}
48#endif
49
50/*
51 * Get the key quota record for a user, allocating a new record if one doesn't
52 * already exist.
53 */
54struct key_user *key_user_lookup(kuid_t uid)
55{
56 struct key_user *candidate = NULL, *user;
57 struct rb_node *parent = NULL;
58 struct rb_node **p;
59
60try_again:
61 p = &key_user_tree.rb_node;
62 spin_lock(&key_user_lock);
63
64 /* search the tree for a user record with a matching UID */
65 while (*p) {
66 parent = *p;
67 user = rb_entry(parent, struct key_user, node);
68
69 if (uid_lt(uid, user->uid))
70 p = &(*p)->rb_left;
71 else if (uid_gt(uid, user->uid))
72 p = &(*p)->rb_right;
73 else
74 goto found;
75 }
76
77 /* if we get here, we failed to find a match in the tree */
78 if (!candidate) {
79 /* allocate a candidate user record if we don't already have
80 * one */
81 spin_unlock(&key_user_lock);
82
83 user = NULL;
84 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
85 if (unlikely(!candidate))
86 goto out;
87
88 /* the allocation may have scheduled, so we need to repeat the
89 * search lest someone else added the record whilst we were
90 * asleep */
91 goto try_again;
92 }
93
94 /* if we get here, then the user record still hadn't appeared on the
95 * second pass - so we use the candidate record */
96 atomic_set(&candidate->usage, 1);
97 atomic_set(&candidate->nkeys, 0);
98 atomic_set(&candidate->nikeys, 0);
99 candidate->uid = uid;
100 candidate->qnkeys = 0;
101 candidate->qnbytes = 0;
102 spin_lock_init(&candidate->lock);
103 mutex_init(&candidate->cons_lock);
104
105 rb_link_node(&candidate->node, parent, p);
106 rb_insert_color(&candidate->node, &key_user_tree);
107 spin_unlock(&key_user_lock);
108 user = candidate;
109 goto out;
110
111 /* okay - we found a user record for this UID */
112found:
113 atomic_inc(&user->usage);
114 spin_unlock(&key_user_lock);
115 kfree(candidate);
116out:
117 return user;
118}
119
120/*
121 * Dispose of a user structure
122 */
123void key_user_put(struct key_user *user)
124{
125 if (atomic_dec_and_lock(&user->usage, &key_user_lock)) {
126 rb_erase(&user->node, &key_user_tree);
127 spin_unlock(&key_user_lock);
128
129 kfree(user);
130 }
131}
132
133/*
134 * Allocate a serial number for a key. These are assigned randomly to avoid
135 * security issues through covert channel problems.
136 */
137static inline void key_alloc_serial(struct key *key)
138{
139 struct rb_node *parent, **p;
140 struct key *xkey;
141
142 /* propose a random serial number and look for a hole for it in the
143 * serial number tree */
144 do {
145 get_random_bytes(&key->serial, sizeof(key->serial));
146
147 key->serial >>= 1; /* negative numbers are not permitted */
148 } while (key->serial < 3);
149
150 spin_lock(&key_serial_lock);
151
152attempt_insertion:
153 parent = NULL;
154 p = &key_serial_tree.rb_node;
155
156 while (*p) {
157 parent = *p;
158 xkey = rb_entry(parent, struct key, serial_node);
159
160 if (key->serial < xkey->serial)
161 p = &(*p)->rb_left;
162 else if (key->serial > xkey->serial)
163 p = &(*p)->rb_right;
164 else
165 goto serial_exists;
166 }
167
168 /* we've found a suitable hole - arrange for this key to occupy it */
169 rb_link_node(&key->serial_node, parent, p);
170 rb_insert_color(&key->serial_node, &key_serial_tree);
171
172 spin_unlock(&key_serial_lock);
173 return;
174
175 /* we found a key with the proposed serial number - walk the tree from
176 * that point looking for the next unused serial number */
177serial_exists:
178 for (;;) {
179 key->serial++;
180 if (key->serial < 3) {
181 key->serial = 3;
182 goto attempt_insertion;
183 }
184
185 parent = rb_next(parent);
186 if (!parent)
187 goto attempt_insertion;
188
189 xkey = rb_entry(parent, struct key, serial_node);
190 if (key->serial < xkey->serial)
191 goto attempt_insertion;
192 }
193}
194
195/**
196 * key_alloc - Allocate a key of the specified type.
197 * @type: The type of key to allocate.
198 * @desc: The key description to allow the key to be searched out.
199 * @uid: The owner of the new key.
200 * @gid: The group ID for the new key's group permissions.
201 * @cred: The credentials specifying UID namespace.
202 * @perm: The permissions mask of the new key.
203 * @flags: Flags specifying quota properties.
204 *
205 * Allocate a key of the specified type with the attributes given. The key is
206 * returned in an uninstantiated state and the caller needs to instantiate the
207 * key before returning.
208 *
209 * The user's key count quota is updated to reflect the creation of the key and
210 * the user's key data quota has the default for the key type reserved. The
211 * instantiation function should amend this as necessary. If insufficient
212 * quota is available, -EDQUOT will be returned.
213 *
214 * The LSM security modules can prevent a key being created, in which case
215 * -EACCES will be returned.
216 *
217 * Returns a pointer to the new key if successful and an error code otherwise.
218 *
219 * Note that the caller needs to ensure the key type isn't uninstantiated.
220 * Internally this can be done by locking key_types_sem. Externally, this can
221 * be done by either never unregistering the key type, or making sure
222 * key_alloc() calls don't race with module unloading.
223 */
224struct key *key_alloc(struct key_type *type, const char *desc,
225 kuid_t uid, kgid_t gid, const struct cred *cred,
226 key_perm_t perm, unsigned long flags)
227{
228 struct key_user *user = NULL;
229 struct key *key;
230 size_t desclen, quotalen;
231 int ret;
232
233 key = ERR_PTR(-EINVAL);
234 if (!desc || !*desc)
235 goto error;
236
237 if (type->vet_description) {
238 ret = type->vet_description(desc);
239 if (ret < 0) {
240 key = ERR_PTR(ret);
241 goto error;
242 }
243 }
244
245 desclen = strlen(desc);
246 quotalen = desclen + 1 + type->def_datalen;
247
248 /* get hold of the key tracking for this user */
249 user = key_user_lookup(uid);
250 if (!user)
251 goto no_memory_1;
252
253 /* check that the user's quota permits allocation of another key and
254 * its description */
255 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
256 unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
257 key_quota_root_maxkeys : key_quota_maxkeys;
258 unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
259 key_quota_root_maxbytes : key_quota_maxbytes;
260
261 spin_lock(&user->lock);
262 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
263 if (user->qnkeys + 1 >= maxkeys ||
264 user->qnbytes + quotalen >= maxbytes ||
265 user->qnbytes + quotalen < user->qnbytes)
266 goto no_quota;
267 }
268
269 user->qnkeys++;
270 user->qnbytes += quotalen;
271 spin_unlock(&user->lock);
272 }
273
274 /* allocate and initialise the key and its description */
275 key = kmem_cache_zalloc(key_jar, GFP_KERNEL);
276 if (!key)
277 goto no_memory_2;
278
279 if (desc) {
280 key->index_key.desc_len = desclen;
281 key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
282 if (!key->description)
283 goto no_memory_3;
284 }
285
286 atomic_set(&key->usage, 1);
287 init_rwsem(&key->sem);
288 lockdep_set_class(&key->sem, &type->lock_class);
289 key->index_key.type = type;
290 key->user = user;
291 key->quotalen = quotalen;
292 key->datalen = type->def_datalen;
293 key->uid = uid;
294 key->gid = gid;
295 key->perm = perm;
296
297 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
298 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
299 if (flags & KEY_ALLOC_TRUSTED)
300 key->flags |= 1 << KEY_FLAG_TRUSTED;
301
302#ifdef KEY_DEBUGGING
303 key->magic = KEY_DEBUG_MAGIC;
304#endif
305
306 /* let the security module know about the key */
307 ret = security_key_alloc(key, cred, flags);
308 if (ret < 0)
309 goto security_error;
310
311 /* publish the key by giving it a serial number */
312 atomic_inc(&user->nkeys);
313 key_alloc_serial(key);
314
315error:
316 return key;
317
318security_error:
319 kfree(key->description);
320 kmem_cache_free(key_jar, key);
321 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
322 spin_lock(&user->lock);
323 user->qnkeys--;
324 user->qnbytes -= quotalen;
325 spin_unlock(&user->lock);
326 }
327 key_user_put(user);
328 key = ERR_PTR(ret);
329 goto error;
330
331no_memory_3:
332 kmem_cache_free(key_jar, key);
333no_memory_2:
334 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
335 spin_lock(&user->lock);
336 user->qnkeys--;
337 user->qnbytes -= quotalen;
338 spin_unlock(&user->lock);
339 }
340 key_user_put(user);
341no_memory_1:
342 key = ERR_PTR(-ENOMEM);
343 goto error;
344
345no_quota:
346 spin_unlock(&user->lock);
347 key_user_put(user);
348 key = ERR_PTR(-EDQUOT);
349 goto error;
350}
351EXPORT_SYMBOL(key_alloc);
352
353/**
354 * key_payload_reserve - Adjust data quota reservation for the key's payload
355 * @key: The key to make the reservation for.
356 * @datalen: The amount of data payload the caller now wants.
357 *
358 * Adjust the amount of the owning user's key data quota that a key reserves.
359 * If the amount is increased, then -EDQUOT may be returned if there isn't
360 * enough free quota available.
361 *
362 * If successful, 0 is returned.
363 */
364int key_payload_reserve(struct key *key, size_t datalen)
365{
366 int delta = (int)datalen - key->datalen;
367 int ret = 0;
368
369 key_check(key);
370
371 /* contemplate the quota adjustment */
372 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
373 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
374 key_quota_root_maxbytes : key_quota_maxbytes;
375
376 spin_lock(&key->user->lock);
377
378 if (delta > 0 &&
379 (key->user->qnbytes + delta >= maxbytes ||
380 key->user->qnbytes + delta < key->user->qnbytes)) {
381 ret = -EDQUOT;
382 }
383 else {
384 key->user->qnbytes += delta;
385 key->quotalen += delta;
386 }
387 spin_unlock(&key->user->lock);
388 }
389
390 /* change the recorded data length if that didn't generate an error */
391 if (ret == 0)
392 key->datalen = datalen;
393
394 return ret;
395}
396EXPORT_SYMBOL(key_payload_reserve);
397
398/*
399 * Instantiate a key and link it into the target keyring atomically. Must be
400 * called with the target keyring's semaphore writelocked. The target key's
401 * semaphore need not be locked as instantiation is serialised by
402 * key_construction_mutex.
403 */
404static int __key_instantiate_and_link(struct key *key,
405 struct key_preparsed_payload *prep,
406 struct key *keyring,
407 struct key *authkey,
408 struct assoc_array_edit **_edit)
409{
410 int ret, awaken;
411
412 key_check(key);
413 key_check(keyring);
414
415 awaken = 0;
416 ret = -EBUSY;
417
418 mutex_lock(&key_construction_mutex);
419
420 /* can't instantiate twice */
421 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
422 /* instantiate the key */
423 ret = key->type->instantiate(key, prep);
424
425 if (ret == 0) {
426 /* mark the key as being instantiated */
427 atomic_inc(&key->user->nikeys);
428 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
429
430 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
431 awaken = 1;
432
433 /* and link it into the destination keyring */
434 if (keyring)
435 __key_link(key, _edit);
436
437 /* disable the authorisation key */
438 if (authkey)
439 key_revoke(authkey);
440 }
441 }
442
443 mutex_unlock(&key_construction_mutex);
444
445 /* wake up anyone waiting for a key to be constructed */
446 if (awaken)
447 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
448
449 return ret;
450}
451
452/**
453 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
454 * @key: The key to instantiate.
455 * @data: The data to use to instantiate the keyring.
456 * @datalen: The length of @data.
457 * @keyring: Keyring to create a link in on success (or NULL).
458 * @authkey: The authorisation token permitting instantiation.
459 *
460 * Instantiate a key that's in the uninstantiated state using the provided data
461 * and, if successful, link it in to the destination keyring if one is
462 * supplied.
463 *
464 * If successful, 0 is returned, the authorisation token is revoked and anyone
465 * waiting for the key is woken up. If the key was already instantiated,
466 * -EBUSY will be returned.
467 */
468int key_instantiate_and_link(struct key *key,
469 const void *data,
470 size_t datalen,
471 struct key *keyring,
472 struct key *authkey)
473{
474 struct key_preparsed_payload prep;
475 struct assoc_array_edit *edit;
476 int ret;
477
478 memset(&prep, 0, sizeof(prep));
479 prep.data = data;
480 prep.datalen = datalen;
481 prep.quotalen = key->type->def_datalen;
482 if (key->type->preparse) {
483 ret = key->type->preparse(&prep);
484 if (ret < 0)
485 goto error;
486 }
487
488 if (keyring) {
489 ret = __key_link_begin(keyring, &key->index_key, &edit);
490 if (ret < 0)
491 goto error_free_preparse;
492 }
493
494 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
495
496 if (keyring)
497 __key_link_end(keyring, &key->index_key, edit);
498
499error_free_preparse:
500 if (key->type->preparse)
501 key->type->free_preparse(&prep);
502error:
503 return ret;
504}
505
506EXPORT_SYMBOL(key_instantiate_and_link);
507
508/**
509 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
510 * @key: The key to instantiate.
511 * @timeout: The timeout on the negative key.
512 * @error: The error to return when the key is hit.
513 * @keyring: Keyring to create a link in on success (or NULL).
514 * @authkey: The authorisation token permitting instantiation.
515 *
516 * Negatively instantiate a key that's in the uninstantiated state and, if
517 * successful, set its timeout and stored error and link it in to the
518 * destination keyring if one is supplied. The key and any links to the key
519 * will be automatically garbage collected after the timeout expires.
520 *
521 * Negative keys are used to rate limit repeated request_key() calls by causing
522 * them to return the stored error code (typically ENOKEY) until the negative
523 * key expires.
524 *
525 * If successful, 0 is returned, the authorisation token is revoked and anyone
526 * waiting for the key is woken up. If the key was already instantiated,
527 * -EBUSY will be returned.
528 */
529int key_reject_and_link(struct key *key,
530 unsigned timeout,
531 unsigned error,
532 struct key *keyring,
533 struct key *authkey)
534{
535 struct assoc_array_edit *edit;
536 struct timespec now;
537 int ret, awaken, link_ret = 0;
538
539 key_check(key);
540 key_check(keyring);
541
542 awaken = 0;
543 ret = -EBUSY;
544
545 if (keyring)
546 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
547
548 mutex_lock(&key_construction_mutex);
549
550 /* can't instantiate twice */
551 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
552 /* mark the key as being negatively instantiated */
553 atomic_inc(&key->user->nikeys);
554 key->type_data.reject_error = -error;
555 smp_wmb();
556 set_bit(KEY_FLAG_NEGATIVE, &key->flags);
557 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
558 now = current_kernel_time();
559 key->expiry = now.tv_sec + timeout;
560 key_schedule_gc(key->expiry + key_gc_delay);
561
562 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
563 awaken = 1;
564
565 ret = 0;
566
567 /* and link it into the destination keyring */
568 if (keyring && link_ret == 0)
569 __key_link(key, &edit);
570
571 /* disable the authorisation key */
572 if (authkey)
573 key_revoke(authkey);
574 }
575
576 mutex_unlock(&key_construction_mutex);
577
578 if (keyring)
579 __key_link_end(keyring, &key->index_key, edit);
580
581 /* wake up anyone waiting for a key to be constructed */
582 if (awaken)
583 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
584
585 return ret == 0 ? link_ret : ret;
586}
587EXPORT_SYMBOL(key_reject_and_link);
588
589/**
590 * key_put - Discard a reference to a key.
591 * @key: The key to discard a reference from.
592 *
593 * Discard a reference to a key, and when all the references are gone, we
594 * schedule the cleanup task to come and pull it out of the tree in process
595 * context at some later time.
596 */
597void key_put(struct key *key)
598{
599 if (key) {
600 key_check(key);
601
602 if (atomic_dec_and_test(&key->usage))
603 schedule_work(&key_gc_work);
604 }
605}
606EXPORT_SYMBOL(key_put);
607
608/*
609 * Find a key by its serial number.
610 */
611struct key *key_lookup(key_serial_t id)
612{
613 struct rb_node *n;
614 struct key *key;
615
616 spin_lock(&key_serial_lock);
617
618 /* search the tree for the specified key */
619 n = key_serial_tree.rb_node;
620 while (n) {
621 key = rb_entry(n, struct key, serial_node);
622
623 if (id < key->serial)
624 n = n->rb_left;
625 else if (id > key->serial)
626 n = n->rb_right;
627 else
628 goto found;
629 }
630
631not_found:
632 key = ERR_PTR(-ENOKEY);
633 goto error;
634
635found:
636 /* pretend it doesn't exist if it is awaiting deletion */
637 if (atomic_read(&key->usage) == 0)
638 goto not_found;
639
640 /* this races with key_put(), but that doesn't matter since key_put()
641 * doesn't actually change the key
642 */
643 __key_get(key);
644
645error:
646 spin_unlock(&key_serial_lock);
647 return key;
648}
649
650/*
651 * Find and lock the specified key type against removal.
652 *
653 * We return with the sem read-locked if successful. If the type wasn't
654 * available -ENOKEY is returned instead.
655 */
656struct key_type *key_type_lookup(const char *type)
657{
658 struct key_type *ktype;
659
660 down_read(&key_types_sem);
661
662 /* look up the key type to see if it's one of the registered kernel
663 * types */
664 list_for_each_entry(ktype, &key_types_list, link) {
665 if (strcmp(ktype->name, type) == 0)
666 goto found_kernel_type;
667 }
668
669 up_read(&key_types_sem);
670 ktype = ERR_PTR(-ENOKEY);
671
672found_kernel_type:
673 return ktype;
674}
675
676void key_set_timeout(struct key *key, unsigned timeout)
677{
678 struct timespec now;
679 time_t expiry = 0;
680
681 /* make the changes with the locks held to prevent races */
682 down_write(&key->sem);
683
684 if (timeout > 0) {
685 now = current_kernel_time();
686 expiry = now.tv_sec + timeout;
687 }
688
689 key->expiry = expiry;
690 key_schedule_gc(key->expiry + key_gc_delay);
691
692 up_write(&key->sem);
693}
694EXPORT_SYMBOL_GPL(key_set_timeout);
695
696/*
697 * Unlock a key type locked by key_type_lookup().
698 */
699void key_type_put(struct key_type *ktype)
700{
701 up_read(&key_types_sem);
702}
703
704/*
705 * Attempt to update an existing key.
706 *
707 * The key is given to us with an incremented refcount that we need to discard
708 * if we get an error.
709 */
710static inline key_ref_t __key_update(key_ref_t key_ref,
711 struct key_preparsed_payload *prep)
712{
713 struct key *key = key_ref_to_ptr(key_ref);
714 int ret;
715
716 /* need write permission on the key to update it */
717 ret = key_permission(key_ref, KEY_WRITE);
718 if (ret < 0)
719 goto error;
720
721 ret = -EEXIST;
722 if (!key->type->update)
723 goto error;
724
725 down_write(&key->sem);
726
727 ret = key->type->update(key, prep);
728 if (ret == 0)
729 /* updating a negative key instantiates it */
730 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
731
732 up_write(&key->sem);
733
734 if (ret < 0)
735 goto error;
736out:
737 return key_ref;
738
739error:
740 key_put(key);
741 key_ref = ERR_PTR(ret);
742 goto out;
743}
744
745/**
746 * key_create_or_update - Update or create and instantiate a key.
747 * @keyring_ref: A pointer to the destination keyring with possession flag.
748 * @type: The type of key.
749 * @description: The searchable description for the key.
750 * @payload: The data to use to instantiate or update the key.
751 * @plen: The length of @payload.
752 * @perm: The permissions mask for a new key.
753 * @flags: The quota flags for a new key.
754 *
755 * Search the destination keyring for a key of the same description and if one
756 * is found, update it, otherwise create and instantiate a new one and create a
757 * link to it from that keyring.
758 *
759 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
760 * concocted.
761 *
762 * Returns a pointer to the new key if successful, -ENODEV if the key type
763 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
764 * caller isn't permitted to modify the keyring or the LSM did not permit
765 * creation of the key.
766 *
767 * On success, the possession flag from the keyring ref will be tacked on to
768 * the key ref before it is returned.
769 */
770key_ref_t key_create_or_update(key_ref_t keyring_ref,
771 const char *type,
772 const char *description,
773 const void *payload,
774 size_t plen,
775 key_perm_t perm,
776 unsigned long flags)
777{
778 struct keyring_index_key index_key = {
779 .description = description,
780 };
781 struct key_preparsed_payload prep;
782 struct assoc_array_edit *edit;
783 const struct cred *cred = current_cred();
784 struct key *keyring, *key = NULL;
785 key_ref_t key_ref;
786 int ret;
787
788 /* look up the key type to see if it's one of the registered kernel
789 * types */
790 index_key.type = key_type_lookup(type);
791 if (IS_ERR(index_key.type)) {
792 key_ref = ERR_PTR(-ENODEV);
793 goto error;
794 }
795
796 key_ref = ERR_PTR(-EINVAL);
797 if (!index_key.type->match || !index_key.type->instantiate ||
798 (!index_key.description && !index_key.type->preparse))
799 goto error_put_type;
800
801 keyring = key_ref_to_ptr(keyring_ref);
802
803 key_check(keyring);
804
805 key_ref = ERR_PTR(-ENOTDIR);
806 if (keyring->type != &key_type_keyring)
807 goto error_put_type;
808
809 memset(&prep, 0, sizeof(prep));
810 prep.data = payload;
811 prep.datalen = plen;
812 prep.quotalen = index_key.type->def_datalen;
813 prep.trusted = flags & KEY_ALLOC_TRUSTED;
814 if (index_key.type->preparse) {
815 ret = index_key.type->preparse(&prep);
816 if (ret < 0) {
817 key_ref = ERR_PTR(ret);
818 goto error_put_type;
819 }
820 if (!index_key.description)
821 index_key.description = prep.description;
822 key_ref = ERR_PTR(-EINVAL);
823 if (!index_key.description)
824 goto error_free_prep;
825 }
826 index_key.desc_len = strlen(index_key.description);
827
828 key_ref = ERR_PTR(-EPERM);
829 if (!prep.trusted && test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags))
830 goto error_free_prep;
831 flags |= prep.trusted ? KEY_ALLOC_TRUSTED : 0;
832
833 ret = __key_link_begin(keyring, &index_key, &edit);
834 if (ret < 0) {
835 key_ref = ERR_PTR(ret);
836 goto error_free_prep;
837 }
838
839 /* if we're going to allocate a new key, we're going to have
840 * to modify the keyring */
841 ret = key_permission(keyring_ref, KEY_WRITE);
842 if (ret < 0) {
843 key_ref = ERR_PTR(ret);
844 goto error_link_end;
845 }
846
847 /* if it's possible to update this type of key, search for an existing
848 * key of the same type and description in the destination keyring and
849 * update that instead if possible
850 */
851 if (index_key.type->update) {
852 key_ref = find_key_to_update(keyring_ref, &index_key);
853 if (key_ref)
854 goto found_matching_key;
855 }
856
857 /* if the client doesn't provide, decide on the permissions we want */
858 if (perm == KEY_PERM_UNDEF) {
859 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
860 perm |= KEY_USR_VIEW;
861
862 if (index_key.type->read)
863 perm |= KEY_POS_READ;
864
865 if (index_key.type == &key_type_keyring ||
866 index_key.type->update)
867 perm |= KEY_POS_WRITE;
868 }
869
870 /* allocate a new key */
871 key = key_alloc(index_key.type, index_key.description,
872 cred->fsuid, cred->fsgid, cred, perm, flags);
873 if (IS_ERR(key)) {
874 key_ref = ERR_CAST(key);
875 goto error_link_end;
876 }
877
878 /* instantiate it and link it into the target keyring */
879 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
880 if (ret < 0) {
881 key_put(key);
882 key_ref = ERR_PTR(ret);
883 goto error_link_end;
884 }
885
886 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
887
888error_link_end:
889 __key_link_end(keyring, &index_key, edit);
890error_free_prep:
891 if (index_key.type->preparse)
892 index_key.type->free_preparse(&prep);
893error_put_type:
894 key_type_put(index_key.type);
895error:
896 return key_ref;
897
898 found_matching_key:
899 /* we found a matching key, so we're going to try to update it
900 * - we can drop the locks first as we have the key pinned
901 */
902 __key_link_end(keyring, &index_key, edit);
903
904 key_ref = __key_update(key_ref, &prep);
905 goto error_free_prep;
906}
907EXPORT_SYMBOL(key_create_or_update);
908
909/**
910 * key_update - Update a key's contents.
911 * @key_ref: The pointer (plus possession flag) to the key.
912 * @payload: The data to be used to update the key.
913 * @plen: The length of @payload.
914 *
915 * Attempt to update the contents of a key with the given payload data. The
916 * caller must be granted Write permission on the key. Negative keys can be
917 * instantiated by this method.
918 *
919 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
920 * type does not support updating. The key type may return other errors.
921 */
922int key_update(key_ref_t key_ref, const void *payload, size_t plen)
923{
924 struct key_preparsed_payload prep;
925 struct key *key = key_ref_to_ptr(key_ref);
926 int ret;
927
928 key_check(key);
929
930 /* the key must be writable */
931 ret = key_permission(key_ref, KEY_WRITE);
932 if (ret < 0)
933 goto error;
934
935 /* attempt to update it if supported */
936 ret = -EOPNOTSUPP;
937 if (!key->type->update)
938 goto error;
939
940 memset(&prep, 0, sizeof(prep));
941 prep.data = payload;
942 prep.datalen = plen;
943 prep.quotalen = key->type->def_datalen;
944 if (key->type->preparse) {
945 ret = key->type->preparse(&prep);
946 if (ret < 0)
947 goto error;
948 }
949
950 down_write(&key->sem);
951
952 ret = key->type->update(key, &prep);
953 if (ret == 0)
954 /* updating a negative key instantiates it */
955 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
956
957 up_write(&key->sem);
958
959 if (key->type->preparse)
960 key->type->free_preparse(&prep);
961error:
962 return ret;
963}
964EXPORT_SYMBOL(key_update);
965
966/**
967 * key_revoke - Revoke a key.
968 * @key: The key to be revoked.
969 *
970 * Mark a key as being revoked and ask the type to free up its resources. The
971 * revocation timeout is set and the key and all its links will be
972 * automatically garbage collected after key_gc_delay amount of time if they
973 * are not manually dealt with first.
974 */
975void key_revoke(struct key *key)
976{
977 struct timespec now;
978 time_t time;
979
980 key_check(key);
981
982 /* make sure no one's trying to change or use the key when we mark it
983 * - we tell lockdep that we might nest because we might be revoking an
984 * authorisation key whilst holding the sem on a key we've just
985 * instantiated
986 */
987 down_write_nested(&key->sem, 1);
988 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
989 key->type->revoke)
990 key->type->revoke(key);
991
992 /* set the death time to no more than the expiry time */
993 now = current_kernel_time();
994 time = now.tv_sec;
995 if (key->revoked_at == 0 || key->revoked_at > time) {
996 key->revoked_at = time;
997 key_schedule_gc(key->revoked_at + key_gc_delay);
998 }
999
1000 up_write(&key->sem);
1001}
1002EXPORT_SYMBOL(key_revoke);
1003
1004/**
1005 * key_invalidate - Invalidate a key.
1006 * @key: The key to be invalidated.
1007 *
1008 * Mark a key as being invalidated and have it cleaned up immediately. The key
1009 * is ignored by all searches and other operations from this point.
1010 */
1011void key_invalidate(struct key *key)
1012{
1013 kenter("%d", key_serial(key));
1014
1015 key_check(key);
1016
1017 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1018 down_write_nested(&key->sem, 1);
1019 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags))
1020 key_schedule_gc_links();
1021 up_write(&key->sem);
1022 }
1023}
1024EXPORT_SYMBOL(key_invalidate);
1025
1026/**
1027 * register_key_type - Register a type of key.
1028 * @ktype: The new key type.
1029 *
1030 * Register a new key type.
1031 *
1032 * Returns 0 on success or -EEXIST if a type of this name already exists.
1033 */
1034int register_key_type(struct key_type *ktype)
1035{
1036 struct key_type *p;
1037 int ret;
1038
1039 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1040
1041 ret = -EEXIST;
1042 down_write(&key_types_sem);
1043
1044 /* disallow key types with the same name */
1045 list_for_each_entry(p, &key_types_list, link) {
1046 if (strcmp(p->name, ktype->name) == 0)
1047 goto out;
1048 }
1049
1050 /* store the type */
1051 list_add(&ktype->link, &key_types_list);
1052
1053 pr_notice("Key type %s registered\n", ktype->name);
1054 ret = 0;
1055
1056out:
1057 up_write(&key_types_sem);
1058 return ret;
1059}
1060EXPORT_SYMBOL(register_key_type);
1061
1062/**
1063 * unregister_key_type - Unregister a type of key.
1064 * @ktype: The key type.
1065 *
1066 * Unregister a key type and mark all the extant keys of this type as dead.
1067 * Those keys of this type are then destroyed to get rid of their payloads and
1068 * they and their links will be garbage collected as soon as possible.
1069 */
1070void unregister_key_type(struct key_type *ktype)
1071{
1072 down_write(&key_types_sem);
1073 list_del_init(&ktype->link);
1074 downgrade_write(&key_types_sem);
1075 key_gc_keytype(ktype);
1076 pr_notice("Key type %s unregistered\n", ktype->name);
1077 up_read(&key_types_sem);
1078}
1079EXPORT_SYMBOL(unregister_key_type);
1080
1081/*
1082 * Initialise the key management state.
1083 */
1084void __init key_init(void)
1085{
1086 /* allocate a slab in which we can store keys */
1087 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1088 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1089
1090 /* add the special key types */
1091 list_add_tail(&key_type_keyring.link, &key_types_list);
1092 list_add_tail(&key_type_dead.link, &key_types_list);
1093 list_add_tail(&key_type_user.link, &key_types_list);
1094 list_add_tail(&key_type_logon.link, &key_types_list);
1095
1096 /* record the root user tracking */
1097 rb_link_node(&root_key_user.node,
1098 NULL,
1099 &key_user_tree.rb_node);
1100
1101 rb_insert_color(&root_key_user.node,
1102 &key_user_tree);
1103}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Basic authentication token and access key management
3 *
4 * Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/export.h>
9#include <linux/init.h>
10#include <linux/poison.h>
11#include <linux/sched.h>
12#include <linux/slab.h>
13#include <linux/security.h>
14#include <linux/workqueue.h>
15#include <linux/random.h>
16#include <linux/err.h>
17#include "internal.h"
18
19struct kmem_cache *key_jar;
20struct rb_root key_serial_tree; /* tree of keys indexed by serial */
21DEFINE_SPINLOCK(key_serial_lock);
22
23struct rb_root key_user_tree; /* tree of quota records indexed by UID */
24DEFINE_SPINLOCK(key_user_lock);
25
26unsigned int key_quota_root_maxkeys = 1000000; /* root's key count quota */
27unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
28unsigned int key_quota_maxkeys = 200; /* general key count quota */
29unsigned int key_quota_maxbytes = 20000; /* general key space quota */
30
31static LIST_HEAD(key_types_list);
32static DECLARE_RWSEM(key_types_sem);
33
34/* We serialise key instantiation and link */
35DEFINE_MUTEX(key_construction_mutex);
36
37#ifdef KEY_DEBUGGING
38void __key_check(const struct key *key)
39{
40 printk("__key_check: key %p {%08x} should be {%08x}\n",
41 key, key->magic, KEY_DEBUG_MAGIC);
42 BUG();
43}
44#endif
45
46/*
47 * Get the key quota record for a user, allocating a new record if one doesn't
48 * already exist.
49 */
50struct key_user *key_user_lookup(kuid_t uid)
51{
52 struct key_user *candidate = NULL, *user;
53 struct rb_node *parent, **p;
54
55try_again:
56 parent = NULL;
57 p = &key_user_tree.rb_node;
58 spin_lock(&key_user_lock);
59
60 /* search the tree for a user record with a matching UID */
61 while (*p) {
62 parent = *p;
63 user = rb_entry(parent, struct key_user, node);
64
65 if (uid_lt(uid, user->uid))
66 p = &(*p)->rb_left;
67 else if (uid_gt(uid, user->uid))
68 p = &(*p)->rb_right;
69 else
70 goto found;
71 }
72
73 /* if we get here, we failed to find a match in the tree */
74 if (!candidate) {
75 /* allocate a candidate user record if we don't already have
76 * one */
77 spin_unlock(&key_user_lock);
78
79 user = NULL;
80 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
81 if (unlikely(!candidate))
82 goto out;
83
84 /* the allocation may have scheduled, so we need to repeat the
85 * search lest someone else added the record whilst we were
86 * asleep */
87 goto try_again;
88 }
89
90 /* if we get here, then the user record still hadn't appeared on the
91 * second pass - so we use the candidate record */
92 refcount_set(&candidate->usage, 1);
93 atomic_set(&candidate->nkeys, 0);
94 atomic_set(&candidate->nikeys, 0);
95 candidate->uid = uid;
96 candidate->qnkeys = 0;
97 candidate->qnbytes = 0;
98 spin_lock_init(&candidate->lock);
99 mutex_init(&candidate->cons_lock);
100
101 rb_link_node(&candidate->node, parent, p);
102 rb_insert_color(&candidate->node, &key_user_tree);
103 spin_unlock(&key_user_lock);
104 user = candidate;
105 goto out;
106
107 /* okay - we found a user record for this UID */
108found:
109 refcount_inc(&user->usage);
110 spin_unlock(&key_user_lock);
111 kfree(candidate);
112out:
113 return user;
114}
115
116/*
117 * Dispose of a user structure
118 */
119void key_user_put(struct key_user *user)
120{
121 if (refcount_dec_and_lock(&user->usage, &key_user_lock)) {
122 rb_erase(&user->node, &key_user_tree);
123 spin_unlock(&key_user_lock);
124
125 kfree(user);
126 }
127}
128
129/*
130 * Allocate a serial number for a key. These are assigned randomly to avoid
131 * security issues through covert channel problems.
132 */
133static inline void key_alloc_serial(struct key *key)
134{
135 struct rb_node *parent, **p;
136 struct key *xkey;
137
138 /* propose a random serial number and look for a hole for it in the
139 * serial number tree */
140 do {
141 get_random_bytes(&key->serial, sizeof(key->serial));
142
143 key->serial >>= 1; /* negative numbers are not permitted */
144 } while (key->serial < 3);
145
146 spin_lock(&key_serial_lock);
147
148attempt_insertion:
149 parent = NULL;
150 p = &key_serial_tree.rb_node;
151
152 while (*p) {
153 parent = *p;
154 xkey = rb_entry(parent, struct key, serial_node);
155
156 if (key->serial < xkey->serial)
157 p = &(*p)->rb_left;
158 else if (key->serial > xkey->serial)
159 p = &(*p)->rb_right;
160 else
161 goto serial_exists;
162 }
163
164 /* we've found a suitable hole - arrange for this key to occupy it */
165 rb_link_node(&key->serial_node, parent, p);
166 rb_insert_color(&key->serial_node, &key_serial_tree);
167
168 spin_unlock(&key_serial_lock);
169 return;
170
171 /* we found a key with the proposed serial number - walk the tree from
172 * that point looking for the next unused serial number */
173serial_exists:
174 for (;;) {
175 key->serial++;
176 if (key->serial < 3) {
177 key->serial = 3;
178 goto attempt_insertion;
179 }
180
181 parent = rb_next(parent);
182 if (!parent)
183 goto attempt_insertion;
184
185 xkey = rb_entry(parent, struct key, serial_node);
186 if (key->serial < xkey->serial)
187 goto attempt_insertion;
188 }
189}
190
191/**
192 * key_alloc - Allocate a key of the specified type.
193 * @type: The type of key to allocate.
194 * @desc: The key description to allow the key to be searched out.
195 * @uid: The owner of the new key.
196 * @gid: The group ID for the new key's group permissions.
197 * @cred: The credentials specifying UID namespace.
198 * @perm: The permissions mask of the new key.
199 * @flags: Flags specifying quota properties.
200 * @restrict_link: Optional link restriction for new keyrings.
201 *
202 * Allocate a key of the specified type with the attributes given. The key is
203 * returned in an uninstantiated state and the caller needs to instantiate the
204 * key before returning.
205 *
206 * The restrict_link structure (if not NULL) will be freed when the
207 * keyring is destroyed, so it must be dynamically allocated.
208 *
209 * The user's key count quota is updated to reflect the creation of the key and
210 * the user's key data quota has the default for the key type reserved. The
211 * instantiation function should amend this as necessary. If insufficient
212 * quota is available, -EDQUOT will be returned.
213 *
214 * The LSM security modules can prevent a key being created, in which case
215 * -EACCES will be returned.
216 *
217 * Returns a pointer to the new key if successful and an error code otherwise.
218 *
219 * Note that the caller needs to ensure the key type isn't uninstantiated.
220 * Internally this can be done by locking key_types_sem. Externally, this can
221 * be done by either never unregistering the key type, or making sure
222 * key_alloc() calls don't race with module unloading.
223 */
224struct key *key_alloc(struct key_type *type, const char *desc,
225 kuid_t uid, kgid_t gid, const struct cred *cred,
226 key_perm_t perm, unsigned long flags,
227 struct key_restriction *restrict_link)
228{
229 struct key_user *user = NULL;
230 struct key *key;
231 size_t desclen, quotalen;
232 int ret;
233
234 key = ERR_PTR(-EINVAL);
235 if (!desc || !*desc)
236 goto error;
237
238 if (type->vet_description) {
239 ret = type->vet_description(desc);
240 if (ret < 0) {
241 key = ERR_PTR(ret);
242 goto error;
243 }
244 }
245
246 desclen = strlen(desc);
247 quotalen = desclen + 1 + type->def_datalen;
248
249 /* get hold of the key tracking for this user */
250 user = key_user_lookup(uid);
251 if (!user)
252 goto no_memory_1;
253
254 /* check that the user's quota permits allocation of another key and
255 * its description */
256 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
257 unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
258 key_quota_root_maxkeys : key_quota_maxkeys;
259 unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
260 key_quota_root_maxbytes : key_quota_maxbytes;
261
262 spin_lock(&user->lock);
263 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
264 if (user->qnkeys + 1 > maxkeys ||
265 user->qnbytes + quotalen > maxbytes ||
266 user->qnbytes + quotalen < user->qnbytes)
267 goto no_quota;
268 }
269
270 user->qnkeys++;
271 user->qnbytes += quotalen;
272 spin_unlock(&user->lock);
273 }
274
275 /* allocate and initialise the key and its description */
276 key = kmem_cache_zalloc(key_jar, GFP_KERNEL);
277 if (!key)
278 goto no_memory_2;
279
280 key->index_key.desc_len = desclen;
281 key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
282 if (!key->index_key.description)
283 goto no_memory_3;
284 key->index_key.type = type;
285 key_set_index_key(&key->index_key);
286
287 refcount_set(&key->usage, 1);
288 init_rwsem(&key->sem);
289 lockdep_set_class(&key->sem, &type->lock_class);
290 key->user = user;
291 key->quotalen = quotalen;
292 key->datalen = type->def_datalen;
293 key->uid = uid;
294 key->gid = gid;
295 key->perm = perm;
296 key->restrict_link = restrict_link;
297 key->last_used_at = ktime_get_real_seconds();
298
299 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
300 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
301 if (flags & KEY_ALLOC_BUILT_IN)
302 key->flags |= 1 << KEY_FLAG_BUILTIN;
303 if (flags & KEY_ALLOC_UID_KEYRING)
304 key->flags |= 1 << KEY_FLAG_UID_KEYRING;
305
306#ifdef KEY_DEBUGGING
307 key->magic = KEY_DEBUG_MAGIC;
308#endif
309
310 /* let the security module know about the key */
311 ret = security_key_alloc(key, cred, flags);
312 if (ret < 0)
313 goto security_error;
314
315 /* publish the key by giving it a serial number */
316 refcount_inc(&key->domain_tag->usage);
317 atomic_inc(&user->nkeys);
318 key_alloc_serial(key);
319
320error:
321 return key;
322
323security_error:
324 kfree(key->description);
325 kmem_cache_free(key_jar, key);
326 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
327 spin_lock(&user->lock);
328 user->qnkeys--;
329 user->qnbytes -= quotalen;
330 spin_unlock(&user->lock);
331 }
332 key_user_put(user);
333 key = ERR_PTR(ret);
334 goto error;
335
336no_memory_3:
337 kmem_cache_free(key_jar, key);
338no_memory_2:
339 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
340 spin_lock(&user->lock);
341 user->qnkeys--;
342 user->qnbytes -= quotalen;
343 spin_unlock(&user->lock);
344 }
345 key_user_put(user);
346no_memory_1:
347 key = ERR_PTR(-ENOMEM);
348 goto error;
349
350no_quota:
351 spin_unlock(&user->lock);
352 key_user_put(user);
353 key = ERR_PTR(-EDQUOT);
354 goto error;
355}
356EXPORT_SYMBOL(key_alloc);
357
358/**
359 * key_payload_reserve - Adjust data quota reservation for the key's payload
360 * @key: The key to make the reservation for.
361 * @datalen: The amount of data payload the caller now wants.
362 *
363 * Adjust the amount of the owning user's key data quota that a key reserves.
364 * If the amount is increased, then -EDQUOT may be returned if there isn't
365 * enough free quota available.
366 *
367 * If successful, 0 is returned.
368 */
369int key_payload_reserve(struct key *key, size_t datalen)
370{
371 int delta = (int)datalen - key->datalen;
372 int ret = 0;
373
374 key_check(key);
375
376 /* contemplate the quota adjustment */
377 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
378 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
379 key_quota_root_maxbytes : key_quota_maxbytes;
380
381 spin_lock(&key->user->lock);
382
383 if (delta > 0 &&
384 (key->user->qnbytes + delta >= maxbytes ||
385 key->user->qnbytes + delta < key->user->qnbytes)) {
386 ret = -EDQUOT;
387 }
388 else {
389 key->user->qnbytes += delta;
390 key->quotalen += delta;
391 }
392 spin_unlock(&key->user->lock);
393 }
394
395 /* change the recorded data length if that didn't generate an error */
396 if (ret == 0)
397 key->datalen = datalen;
398
399 return ret;
400}
401EXPORT_SYMBOL(key_payload_reserve);
402
403/*
404 * Change the key state to being instantiated.
405 */
406static void mark_key_instantiated(struct key *key, int reject_error)
407{
408 /* Commit the payload before setting the state; barrier versus
409 * key_read_state().
410 */
411 smp_store_release(&key->state,
412 (reject_error < 0) ? reject_error : KEY_IS_POSITIVE);
413}
414
415/*
416 * Instantiate a key and link it into the target keyring atomically. Must be
417 * called with the target keyring's semaphore writelocked. The target key's
418 * semaphore need not be locked as instantiation is serialised by
419 * key_construction_mutex.
420 */
421static int __key_instantiate_and_link(struct key *key,
422 struct key_preparsed_payload *prep,
423 struct key *keyring,
424 struct key *authkey,
425 struct assoc_array_edit **_edit)
426{
427 int ret, awaken;
428
429 key_check(key);
430 key_check(keyring);
431
432 awaken = 0;
433 ret = -EBUSY;
434
435 mutex_lock(&key_construction_mutex);
436
437 /* can't instantiate twice */
438 if (key->state == KEY_IS_UNINSTANTIATED) {
439 /* instantiate the key */
440 ret = key->type->instantiate(key, prep);
441
442 if (ret == 0) {
443 /* mark the key as being instantiated */
444 atomic_inc(&key->user->nikeys);
445 mark_key_instantiated(key, 0);
446
447 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
448 awaken = 1;
449
450 /* and link it into the destination keyring */
451 if (keyring) {
452 if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
453 set_bit(KEY_FLAG_KEEP, &key->flags);
454
455 __key_link(key, _edit);
456 }
457
458 /* disable the authorisation key */
459 if (authkey)
460 key_invalidate(authkey);
461
462 if (prep->expiry != TIME64_MAX) {
463 key->expiry = prep->expiry;
464 key_schedule_gc(prep->expiry + key_gc_delay);
465 }
466 }
467 }
468
469 mutex_unlock(&key_construction_mutex);
470
471 /* wake up anyone waiting for a key to be constructed */
472 if (awaken)
473 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
474
475 return ret;
476}
477
478/**
479 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
480 * @key: The key to instantiate.
481 * @data: The data to use to instantiate the keyring.
482 * @datalen: The length of @data.
483 * @keyring: Keyring to create a link in on success (or NULL).
484 * @authkey: The authorisation token permitting instantiation.
485 *
486 * Instantiate a key that's in the uninstantiated state using the provided data
487 * and, if successful, link it in to the destination keyring if one is
488 * supplied.
489 *
490 * If successful, 0 is returned, the authorisation token is revoked and anyone
491 * waiting for the key is woken up. If the key was already instantiated,
492 * -EBUSY will be returned.
493 */
494int key_instantiate_and_link(struct key *key,
495 const void *data,
496 size_t datalen,
497 struct key *keyring,
498 struct key *authkey)
499{
500 struct key_preparsed_payload prep;
501 struct assoc_array_edit *edit = NULL;
502 int ret;
503
504 memset(&prep, 0, sizeof(prep));
505 prep.data = data;
506 prep.datalen = datalen;
507 prep.quotalen = key->type->def_datalen;
508 prep.expiry = TIME64_MAX;
509 if (key->type->preparse) {
510 ret = key->type->preparse(&prep);
511 if (ret < 0)
512 goto error;
513 }
514
515 if (keyring) {
516 ret = __key_link_lock(keyring, &key->index_key);
517 if (ret < 0)
518 goto error;
519
520 ret = __key_link_begin(keyring, &key->index_key, &edit);
521 if (ret < 0)
522 goto error_link_end;
523
524 if (keyring->restrict_link && keyring->restrict_link->check) {
525 struct key_restriction *keyres = keyring->restrict_link;
526
527 ret = keyres->check(keyring, key->type, &prep.payload,
528 keyres->key);
529 if (ret < 0)
530 goto error_link_end;
531 }
532 }
533
534 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
535
536error_link_end:
537 if (keyring)
538 __key_link_end(keyring, &key->index_key, edit);
539
540error:
541 if (key->type->preparse)
542 key->type->free_preparse(&prep);
543 return ret;
544}
545
546EXPORT_SYMBOL(key_instantiate_and_link);
547
548/**
549 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
550 * @key: The key to instantiate.
551 * @timeout: The timeout on the negative key.
552 * @error: The error to return when the key is hit.
553 * @keyring: Keyring to create a link in on success (or NULL).
554 * @authkey: The authorisation token permitting instantiation.
555 *
556 * Negatively instantiate a key that's in the uninstantiated state and, if
557 * successful, set its timeout and stored error and link it in to the
558 * destination keyring if one is supplied. The key and any links to the key
559 * will be automatically garbage collected after the timeout expires.
560 *
561 * Negative keys are used to rate limit repeated request_key() calls by causing
562 * them to return the stored error code (typically ENOKEY) until the negative
563 * key expires.
564 *
565 * If successful, 0 is returned, the authorisation token is revoked and anyone
566 * waiting for the key is woken up. If the key was already instantiated,
567 * -EBUSY will be returned.
568 */
569int key_reject_and_link(struct key *key,
570 unsigned timeout,
571 unsigned error,
572 struct key *keyring,
573 struct key *authkey)
574{
575 struct assoc_array_edit *edit = NULL;
576 int ret, awaken, link_ret = 0;
577
578 key_check(key);
579 key_check(keyring);
580
581 awaken = 0;
582 ret = -EBUSY;
583
584 if (keyring) {
585 if (keyring->restrict_link)
586 return -EPERM;
587
588 link_ret = __key_link_lock(keyring, &key->index_key);
589 if (link_ret == 0) {
590 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
591 if (link_ret < 0)
592 __key_link_end(keyring, &key->index_key, edit);
593 }
594 }
595
596 mutex_lock(&key_construction_mutex);
597
598 /* can't instantiate twice */
599 if (key->state == KEY_IS_UNINSTANTIATED) {
600 /* mark the key as being negatively instantiated */
601 atomic_inc(&key->user->nikeys);
602 mark_key_instantiated(key, -error);
603 key->expiry = ktime_get_real_seconds() + timeout;
604 key_schedule_gc(key->expiry + key_gc_delay);
605
606 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
607 awaken = 1;
608
609 ret = 0;
610
611 /* and link it into the destination keyring */
612 if (keyring && link_ret == 0)
613 __key_link(key, &edit);
614
615 /* disable the authorisation key */
616 if (authkey)
617 key_invalidate(authkey);
618 }
619
620 mutex_unlock(&key_construction_mutex);
621
622 if (keyring && link_ret == 0)
623 __key_link_end(keyring, &key->index_key, edit);
624
625 /* wake up anyone waiting for a key to be constructed */
626 if (awaken)
627 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
628
629 return ret == 0 ? link_ret : ret;
630}
631EXPORT_SYMBOL(key_reject_and_link);
632
633/**
634 * key_put - Discard a reference to a key.
635 * @key: The key to discard a reference from.
636 *
637 * Discard a reference to a key, and when all the references are gone, we
638 * schedule the cleanup task to come and pull it out of the tree in process
639 * context at some later time.
640 */
641void key_put(struct key *key)
642{
643 if (key) {
644 key_check(key);
645
646 if (refcount_dec_and_test(&key->usage))
647 schedule_work(&key_gc_work);
648 }
649}
650EXPORT_SYMBOL(key_put);
651
652/*
653 * Find a key by its serial number.
654 */
655struct key *key_lookup(key_serial_t id)
656{
657 struct rb_node *n;
658 struct key *key;
659
660 spin_lock(&key_serial_lock);
661
662 /* search the tree for the specified key */
663 n = key_serial_tree.rb_node;
664 while (n) {
665 key = rb_entry(n, struct key, serial_node);
666
667 if (id < key->serial)
668 n = n->rb_left;
669 else if (id > key->serial)
670 n = n->rb_right;
671 else
672 goto found;
673 }
674
675not_found:
676 key = ERR_PTR(-ENOKEY);
677 goto error;
678
679found:
680 /* A key is allowed to be looked up only if someone still owns a
681 * reference to it - otherwise it's awaiting the gc.
682 */
683 if (!refcount_inc_not_zero(&key->usage))
684 goto not_found;
685
686error:
687 spin_unlock(&key_serial_lock);
688 return key;
689}
690
691/*
692 * Find and lock the specified key type against removal.
693 *
694 * We return with the sem read-locked if successful. If the type wasn't
695 * available -ENOKEY is returned instead.
696 */
697struct key_type *key_type_lookup(const char *type)
698{
699 struct key_type *ktype;
700
701 down_read(&key_types_sem);
702
703 /* look up the key type to see if it's one of the registered kernel
704 * types */
705 list_for_each_entry(ktype, &key_types_list, link) {
706 if (strcmp(ktype->name, type) == 0)
707 goto found_kernel_type;
708 }
709
710 up_read(&key_types_sem);
711 ktype = ERR_PTR(-ENOKEY);
712
713found_kernel_type:
714 return ktype;
715}
716
717void key_set_timeout(struct key *key, unsigned timeout)
718{
719 time64_t expiry = 0;
720
721 /* make the changes with the locks held to prevent races */
722 down_write(&key->sem);
723
724 if (timeout > 0)
725 expiry = ktime_get_real_seconds() + timeout;
726
727 key->expiry = expiry;
728 key_schedule_gc(key->expiry + key_gc_delay);
729
730 up_write(&key->sem);
731}
732EXPORT_SYMBOL_GPL(key_set_timeout);
733
734/*
735 * Unlock a key type locked by key_type_lookup().
736 */
737void key_type_put(struct key_type *ktype)
738{
739 up_read(&key_types_sem);
740}
741
742/*
743 * Attempt to update an existing key.
744 *
745 * The key is given to us with an incremented refcount that we need to discard
746 * if we get an error.
747 */
748static inline key_ref_t __key_update(key_ref_t key_ref,
749 struct key_preparsed_payload *prep)
750{
751 struct key *key = key_ref_to_ptr(key_ref);
752 int ret;
753
754 /* need write permission on the key to update it */
755 ret = key_permission(key_ref, KEY_NEED_WRITE);
756 if (ret < 0)
757 goto error;
758
759 ret = -EEXIST;
760 if (!key->type->update)
761 goto error;
762
763 down_write(&key->sem);
764
765 ret = key->type->update(key, prep);
766 if (ret == 0)
767 /* Updating a negative key positively instantiates it */
768 mark_key_instantiated(key, 0);
769
770 up_write(&key->sem);
771
772 if (ret < 0)
773 goto error;
774out:
775 return key_ref;
776
777error:
778 key_put(key);
779 key_ref = ERR_PTR(ret);
780 goto out;
781}
782
783/**
784 * key_create_or_update - Update or create and instantiate a key.
785 * @keyring_ref: A pointer to the destination keyring with possession flag.
786 * @type: The type of key.
787 * @description: The searchable description for the key.
788 * @payload: The data to use to instantiate or update the key.
789 * @plen: The length of @payload.
790 * @perm: The permissions mask for a new key.
791 * @flags: The quota flags for a new key.
792 *
793 * Search the destination keyring for a key of the same description and if one
794 * is found, update it, otherwise create and instantiate a new one and create a
795 * link to it from that keyring.
796 *
797 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
798 * concocted.
799 *
800 * Returns a pointer to the new key if successful, -ENODEV if the key type
801 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
802 * caller isn't permitted to modify the keyring or the LSM did not permit
803 * creation of the key.
804 *
805 * On success, the possession flag from the keyring ref will be tacked on to
806 * the key ref before it is returned.
807 */
808key_ref_t key_create_or_update(key_ref_t keyring_ref,
809 const char *type,
810 const char *description,
811 const void *payload,
812 size_t plen,
813 key_perm_t perm,
814 unsigned long flags)
815{
816 struct keyring_index_key index_key = {
817 .description = description,
818 };
819 struct key_preparsed_payload prep;
820 struct assoc_array_edit *edit = NULL;
821 const struct cred *cred = current_cred();
822 struct key *keyring, *key = NULL;
823 key_ref_t key_ref;
824 int ret;
825 struct key_restriction *restrict_link = NULL;
826
827 /* look up the key type to see if it's one of the registered kernel
828 * types */
829 index_key.type = key_type_lookup(type);
830 if (IS_ERR(index_key.type)) {
831 key_ref = ERR_PTR(-ENODEV);
832 goto error;
833 }
834
835 key_ref = ERR_PTR(-EINVAL);
836 if (!index_key.type->instantiate ||
837 (!index_key.description && !index_key.type->preparse))
838 goto error_put_type;
839
840 keyring = key_ref_to_ptr(keyring_ref);
841
842 key_check(keyring);
843
844 if (!(flags & KEY_ALLOC_BYPASS_RESTRICTION))
845 restrict_link = keyring->restrict_link;
846
847 key_ref = ERR_PTR(-ENOTDIR);
848 if (keyring->type != &key_type_keyring)
849 goto error_put_type;
850
851 memset(&prep, 0, sizeof(prep));
852 prep.data = payload;
853 prep.datalen = plen;
854 prep.quotalen = index_key.type->def_datalen;
855 prep.expiry = TIME64_MAX;
856 if (index_key.type->preparse) {
857 ret = index_key.type->preparse(&prep);
858 if (ret < 0) {
859 key_ref = ERR_PTR(ret);
860 goto error_free_prep;
861 }
862 if (!index_key.description)
863 index_key.description = prep.description;
864 key_ref = ERR_PTR(-EINVAL);
865 if (!index_key.description)
866 goto error_free_prep;
867 }
868 index_key.desc_len = strlen(index_key.description);
869 key_set_index_key(&index_key);
870
871 ret = __key_link_lock(keyring, &index_key);
872 if (ret < 0) {
873 key_ref = ERR_PTR(ret);
874 goto error_free_prep;
875 }
876
877 ret = __key_link_begin(keyring, &index_key, &edit);
878 if (ret < 0) {
879 key_ref = ERR_PTR(ret);
880 goto error_link_end;
881 }
882
883 if (restrict_link && restrict_link->check) {
884 ret = restrict_link->check(keyring, index_key.type,
885 &prep.payload, restrict_link->key);
886 if (ret < 0) {
887 key_ref = ERR_PTR(ret);
888 goto error_link_end;
889 }
890 }
891
892 /* if we're going to allocate a new key, we're going to have
893 * to modify the keyring */
894 ret = key_permission(keyring_ref, KEY_NEED_WRITE);
895 if (ret < 0) {
896 key_ref = ERR_PTR(ret);
897 goto error_link_end;
898 }
899
900 /* if it's possible to update this type of key, search for an existing
901 * key of the same type and description in the destination keyring and
902 * update that instead if possible
903 */
904 if (index_key.type->update) {
905 key_ref = find_key_to_update(keyring_ref, &index_key);
906 if (key_ref)
907 goto found_matching_key;
908 }
909
910 /* if the client doesn't provide, decide on the permissions we want */
911 if (perm == KEY_PERM_UNDEF) {
912 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
913 perm |= KEY_USR_VIEW;
914
915 if (index_key.type->read)
916 perm |= KEY_POS_READ;
917
918 if (index_key.type == &key_type_keyring ||
919 index_key.type->update)
920 perm |= KEY_POS_WRITE;
921 }
922
923 /* allocate a new key */
924 key = key_alloc(index_key.type, index_key.description,
925 cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
926 if (IS_ERR(key)) {
927 key_ref = ERR_CAST(key);
928 goto error_link_end;
929 }
930
931 /* instantiate it and link it into the target keyring */
932 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
933 if (ret < 0) {
934 key_put(key);
935 key_ref = ERR_PTR(ret);
936 goto error_link_end;
937 }
938
939 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
940
941error_link_end:
942 __key_link_end(keyring, &index_key, edit);
943error_free_prep:
944 if (index_key.type->preparse)
945 index_key.type->free_preparse(&prep);
946error_put_type:
947 key_type_put(index_key.type);
948error:
949 return key_ref;
950
951 found_matching_key:
952 /* we found a matching key, so we're going to try to update it
953 * - we can drop the locks first as we have the key pinned
954 */
955 __key_link_end(keyring, &index_key, edit);
956
957 key = key_ref_to_ptr(key_ref);
958 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) {
959 ret = wait_for_key_construction(key, true);
960 if (ret < 0) {
961 key_ref_put(key_ref);
962 key_ref = ERR_PTR(ret);
963 goto error_free_prep;
964 }
965 }
966
967 key_ref = __key_update(key_ref, &prep);
968 goto error_free_prep;
969}
970EXPORT_SYMBOL(key_create_or_update);
971
972/**
973 * key_update - Update a key's contents.
974 * @key_ref: The pointer (plus possession flag) to the key.
975 * @payload: The data to be used to update the key.
976 * @plen: The length of @payload.
977 *
978 * Attempt to update the contents of a key with the given payload data. The
979 * caller must be granted Write permission on the key. Negative keys can be
980 * instantiated by this method.
981 *
982 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
983 * type does not support updating. The key type may return other errors.
984 */
985int key_update(key_ref_t key_ref, const void *payload, size_t plen)
986{
987 struct key_preparsed_payload prep;
988 struct key *key = key_ref_to_ptr(key_ref);
989 int ret;
990
991 key_check(key);
992
993 /* the key must be writable */
994 ret = key_permission(key_ref, KEY_NEED_WRITE);
995 if (ret < 0)
996 return ret;
997
998 /* attempt to update it if supported */
999 if (!key->type->update)
1000 return -EOPNOTSUPP;
1001
1002 memset(&prep, 0, sizeof(prep));
1003 prep.data = payload;
1004 prep.datalen = plen;
1005 prep.quotalen = key->type->def_datalen;
1006 prep.expiry = TIME64_MAX;
1007 if (key->type->preparse) {
1008 ret = key->type->preparse(&prep);
1009 if (ret < 0)
1010 goto error;
1011 }
1012
1013 down_write(&key->sem);
1014
1015 ret = key->type->update(key, &prep);
1016 if (ret == 0)
1017 /* Updating a negative key positively instantiates it */
1018 mark_key_instantiated(key, 0);
1019
1020 up_write(&key->sem);
1021
1022error:
1023 if (key->type->preparse)
1024 key->type->free_preparse(&prep);
1025 return ret;
1026}
1027EXPORT_SYMBOL(key_update);
1028
1029/**
1030 * key_revoke - Revoke a key.
1031 * @key: The key to be revoked.
1032 *
1033 * Mark a key as being revoked and ask the type to free up its resources. The
1034 * revocation timeout is set and the key and all its links will be
1035 * automatically garbage collected after key_gc_delay amount of time if they
1036 * are not manually dealt with first.
1037 */
1038void key_revoke(struct key *key)
1039{
1040 time64_t time;
1041
1042 key_check(key);
1043
1044 /* make sure no one's trying to change or use the key when we mark it
1045 * - we tell lockdep that we might nest because we might be revoking an
1046 * authorisation key whilst holding the sem on a key we've just
1047 * instantiated
1048 */
1049 down_write_nested(&key->sem, 1);
1050 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
1051 key->type->revoke)
1052 key->type->revoke(key);
1053
1054 /* set the death time to no more than the expiry time */
1055 time = ktime_get_real_seconds();
1056 if (key->revoked_at == 0 || key->revoked_at > time) {
1057 key->revoked_at = time;
1058 key_schedule_gc(key->revoked_at + key_gc_delay);
1059 }
1060
1061 up_write(&key->sem);
1062}
1063EXPORT_SYMBOL(key_revoke);
1064
1065/**
1066 * key_invalidate - Invalidate a key.
1067 * @key: The key to be invalidated.
1068 *
1069 * Mark a key as being invalidated and have it cleaned up immediately. The key
1070 * is ignored by all searches and other operations from this point.
1071 */
1072void key_invalidate(struct key *key)
1073{
1074 kenter("%d", key_serial(key));
1075
1076 key_check(key);
1077
1078 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1079 down_write_nested(&key->sem, 1);
1080 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags))
1081 key_schedule_gc_links();
1082 up_write(&key->sem);
1083 }
1084}
1085EXPORT_SYMBOL(key_invalidate);
1086
1087/**
1088 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1089 * @key: The key to be instantiated
1090 * @prep: The preparsed data to load.
1091 *
1092 * Instantiate a key from preparsed data. We assume we can just copy the data
1093 * in directly and clear the old pointers.
1094 *
1095 * This can be pointed to directly by the key type instantiate op pointer.
1096 */
1097int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1098{
1099 int ret;
1100
1101 pr_devel("==>%s()\n", __func__);
1102
1103 ret = key_payload_reserve(key, prep->quotalen);
1104 if (ret == 0) {
1105 rcu_assign_keypointer(key, prep->payload.data[0]);
1106 key->payload.data[1] = prep->payload.data[1];
1107 key->payload.data[2] = prep->payload.data[2];
1108 key->payload.data[3] = prep->payload.data[3];
1109 prep->payload.data[0] = NULL;
1110 prep->payload.data[1] = NULL;
1111 prep->payload.data[2] = NULL;
1112 prep->payload.data[3] = NULL;
1113 }
1114 pr_devel("<==%s() = %d\n", __func__, ret);
1115 return ret;
1116}
1117EXPORT_SYMBOL(generic_key_instantiate);
1118
1119/**
1120 * register_key_type - Register a type of key.
1121 * @ktype: The new key type.
1122 *
1123 * Register a new key type.
1124 *
1125 * Returns 0 on success or -EEXIST if a type of this name already exists.
1126 */
1127int register_key_type(struct key_type *ktype)
1128{
1129 struct key_type *p;
1130 int ret;
1131
1132 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1133
1134 ret = -EEXIST;
1135 down_write(&key_types_sem);
1136
1137 /* disallow key types with the same name */
1138 list_for_each_entry(p, &key_types_list, link) {
1139 if (strcmp(p->name, ktype->name) == 0)
1140 goto out;
1141 }
1142
1143 /* store the type */
1144 list_add(&ktype->link, &key_types_list);
1145
1146 pr_notice("Key type %s registered\n", ktype->name);
1147 ret = 0;
1148
1149out:
1150 up_write(&key_types_sem);
1151 return ret;
1152}
1153EXPORT_SYMBOL(register_key_type);
1154
1155/**
1156 * unregister_key_type - Unregister a type of key.
1157 * @ktype: The key type.
1158 *
1159 * Unregister a key type and mark all the extant keys of this type as dead.
1160 * Those keys of this type are then destroyed to get rid of their payloads and
1161 * they and their links will be garbage collected as soon as possible.
1162 */
1163void unregister_key_type(struct key_type *ktype)
1164{
1165 down_write(&key_types_sem);
1166 list_del_init(&ktype->link);
1167 downgrade_write(&key_types_sem);
1168 key_gc_keytype(ktype);
1169 pr_notice("Key type %s unregistered\n", ktype->name);
1170 up_read(&key_types_sem);
1171}
1172EXPORT_SYMBOL(unregister_key_type);
1173
1174/*
1175 * Initialise the key management state.
1176 */
1177void __init key_init(void)
1178{
1179 /* allocate a slab in which we can store keys */
1180 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1181 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1182
1183 /* add the special key types */
1184 list_add_tail(&key_type_keyring.link, &key_types_list);
1185 list_add_tail(&key_type_dead.link, &key_types_list);
1186 list_add_tail(&key_type_user.link, &key_types_list);
1187 list_add_tail(&key_type_logon.link, &key_types_list);
1188
1189 /* record the root user tracking */
1190 rb_link_node(&root_key_user.node,
1191 NULL,
1192 &key_user_tree.rb_node);
1193
1194 rb_insert_color(&root_key_user.node,
1195 &key_user_tree);
1196}