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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Basic authentication token and access key management
3 *
4 * Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/export.h>
9#include <linux/init.h>
10#include <linux/poison.h>
11#include <linux/sched.h>
12#include <linux/slab.h>
13#include <linux/security.h>
14#include <linux/workqueue.h>
15#include <linux/random.h>
16#include <linux/ima.h>
17#include <linux/err.h>
18#include "internal.h"
19
20struct kmem_cache *key_jar;
21struct rb_root key_serial_tree; /* tree of keys indexed by serial */
22DEFINE_SPINLOCK(key_serial_lock);
23
24struct rb_root key_user_tree; /* tree of quota records indexed by UID */
25DEFINE_SPINLOCK(key_user_lock);
26
27unsigned int key_quota_root_maxkeys = 1000000; /* root's key count quota */
28unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
29unsigned int key_quota_maxkeys = 200; /* general key count quota */
30unsigned int key_quota_maxbytes = 20000; /* general key space quota */
31
32static LIST_HEAD(key_types_list);
33static DECLARE_RWSEM(key_types_sem);
34
35/* We serialise key instantiation and link */
36DEFINE_MUTEX(key_construction_mutex);
37
38#ifdef KEY_DEBUGGING
39void __key_check(const struct key *key)
40{
41 printk("__key_check: key %p {%08x} should be {%08x}\n",
42 key, key->magic, KEY_DEBUG_MAGIC);
43 BUG();
44}
45#endif
46
47/*
48 * Get the key quota record for a user, allocating a new record if one doesn't
49 * already exist.
50 */
51struct key_user *key_user_lookup(kuid_t uid)
52{
53 struct key_user *candidate = NULL, *user;
54 struct rb_node *parent, **p;
55
56try_again:
57 parent = NULL;
58 p = &key_user_tree.rb_node;
59 spin_lock(&key_user_lock);
60
61 /* search the tree for a user record with a matching UID */
62 while (*p) {
63 parent = *p;
64 user = rb_entry(parent, struct key_user, node);
65
66 if (uid_lt(uid, user->uid))
67 p = &(*p)->rb_left;
68 else if (uid_gt(uid, user->uid))
69 p = &(*p)->rb_right;
70 else
71 goto found;
72 }
73
74 /* if we get here, we failed to find a match in the tree */
75 if (!candidate) {
76 /* allocate a candidate user record if we don't already have
77 * one */
78 spin_unlock(&key_user_lock);
79
80 user = NULL;
81 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
82 if (unlikely(!candidate))
83 goto out;
84
85 /* the allocation may have scheduled, so we need to repeat the
86 * search lest someone else added the record whilst we were
87 * asleep */
88 goto try_again;
89 }
90
91 /* if we get here, then the user record still hadn't appeared on the
92 * second pass - so we use the candidate record */
93 refcount_set(&candidate->usage, 1);
94 atomic_set(&candidate->nkeys, 0);
95 atomic_set(&candidate->nikeys, 0);
96 candidate->uid = uid;
97 candidate->qnkeys = 0;
98 candidate->qnbytes = 0;
99 spin_lock_init(&candidate->lock);
100 mutex_init(&candidate->cons_lock);
101
102 rb_link_node(&candidate->node, parent, p);
103 rb_insert_color(&candidate->node, &key_user_tree);
104 spin_unlock(&key_user_lock);
105 user = candidate;
106 goto out;
107
108 /* okay - we found a user record for this UID */
109found:
110 refcount_inc(&user->usage);
111 spin_unlock(&key_user_lock);
112 kfree(candidate);
113out:
114 return user;
115}
116
117/*
118 * Dispose of a user structure
119 */
120void key_user_put(struct key_user *user)
121{
122 if (refcount_dec_and_lock(&user->usage, &key_user_lock)) {
123 rb_erase(&user->node, &key_user_tree);
124 spin_unlock(&key_user_lock);
125
126 kfree(user);
127 }
128}
129
130/*
131 * Allocate a serial number for a key. These are assigned randomly to avoid
132 * security issues through covert channel problems.
133 */
134static inline void key_alloc_serial(struct key *key)
135{
136 struct rb_node *parent, **p;
137 struct key *xkey;
138
139 /* propose a random serial number and look for a hole for it in the
140 * serial number tree */
141 do {
142 get_random_bytes(&key->serial, sizeof(key->serial));
143
144 key->serial >>= 1; /* negative numbers are not permitted */
145 } while (key->serial < 3);
146
147 spin_lock(&key_serial_lock);
148
149attempt_insertion:
150 parent = NULL;
151 p = &key_serial_tree.rb_node;
152
153 while (*p) {
154 parent = *p;
155 xkey = rb_entry(parent, struct key, serial_node);
156
157 if (key->serial < xkey->serial)
158 p = &(*p)->rb_left;
159 else if (key->serial > xkey->serial)
160 p = &(*p)->rb_right;
161 else
162 goto serial_exists;
163 }
164
165 /* we've found a suitable hole - arrange for this key to occupy it */
166 rb_link_node(&key->serial_node, parent, p);
167 rb_insert_color(&key->serial_node, &key_serial_tree);
168
169 spin_unlock(&key_serial_lock);
170 return;
171
172 /* we found a key with the proposed serial number - walk the tree from
173 * that point looking for the next unused serial number */
174serial_exists:
175 for (;;) {
176 key->serial++;
177 if (key->serial < 3) {
178 key->serial = 3;
179 goto attempt_insertion;
180 }
181
182 parent = rb_next(parent);
183 if (!parent)
184 goto attempt_insertion;
185
186 xkey = rb_entry(parent, struct key, serial_node);
187 if (key->serial < xkey->serial)
188 goto attempt_insertion;
189 }
190}
191
192/**
193 * key_alloc - Allocate a key of the specified type.
194 * @type: The type of key to allocate.
195 * @desc: The key description to allow the key to be searched out.
196 * @uid: The owner of the new key.
197 * @gid: The group ID for the new key's group permissions.
198 * @cred: The credentials specifying UID namespace.
199 * @perm: The permissions mask of the new key.
200 * @flags: Flags specifying quota properties.
201 * @restrict_link: Optional link restriction for new keyrings.
202 *
203 * Allocate a key of the specified type with the attributes given. The key is
204 * returned in an uninstantiated state and the caller needs to instantiate the
205 * key before returning.
206 *
207 * The restrict_link structure (if not NULL) will be freed when the
208 * keyring is destroyed, so it must be dynamically allocated.
209 *
210 * The user's key count quota is updated to reflect the creation of the key and
211 * the user's key data quota has the default for the key type reserved. The
212 * instantiation function should amend this as necessary. If insufficient
213 * quota is available, -EDQUOT will be returned.
214 *
215 * The LSM security modules can prevent a key being created, in which case
216 * -EACCES will be returned.
217 *
218 * Returns a pointer to the new key if successful and an error code otherwise.
219 *
220 * Note that the caller needs to ensure the key type isn't uninstantiated.
221 * Internally this can be done by locking key_types_sem. Externally, this can
222 * be done by either never unregistering the key type, or making sure
223 * key_alloc() calls don't race with module unloading.
224 */
225struct key *key_alloc(struct key_type *type, const char *desc,
226 kuid_t uid, kgid_t gid, const struct cred *cred,
227 key_perm_t perm, unsigned long flags,
228 struct key_restriction *restrict_link)
229{
230 struct key_user *user = NULL;
231 struct key *key;
232 size_t desclen, quotalen;
233 int ret;
234
235 key = ERR_PTR(-EINVAL);
236 if (!desc || !*desc)
237 goto error;
238
239 if (type->vet_description) {
240 ret = type->vet_description(desc);
241 if (ret < 0) {
242 key = ERR_PTR(ret);
243 goto error;
244 }
245 }
246
247 desclen = strlen(desc);
248 quotalen = desclen + 1 + type->def_datalen;
249
250 /* get hold of the key tracking for this user */
251 user = key_user_lookup(uid);
252 if (!user)
253 goto no_memory_1;
254
255 /* check that the user's quota permits allocation of another key and
256 * its description */
257 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
258 unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
259 key_quota_root_maxkeys : key_quota_maxkeys;
260 unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
261 key_quota_root_maxbytes : key_quota_maxbytes;
262
263 spin_lock(&user->lock);
264 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
265 if (user->qnkeys + 1 > maxkeys ||
266 user->qnbytes + quotalen > maxbytes ||
267 user->qnbytes + quotalen < user->qnbytes)
268 goto no_quota;
269 }
270
271 user->qnkeys++;
272 user->qnbytes += quotalen;
273 spin_unlock(&user->lock);
274 }
275
276 /* allocate and initialise the key and its description */
277 key = kmem_cache_zalloc(key_jar, GFP_KERNEL);
278 if (!key)
279 goto no_memory_2;
280
281 key->index_key.desc_len = desclen;
282 key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
283 if (!key->index_key.description)
284 goto no_memory_3;
285 key->index_key.type = type;
286 key_set_index_key(&key->index_key);
287
288 refcount_set(&key->usage, 1);
289 init_rwsem(&key->sem);
290 lockdep_set_class(&key->sem, &type->lock_class);
291 key->user = user;
292 key->quotalen = quotalen;
293 key->datalen = type->def_datalen;
294 key->uid = uid;
295 key->gid = gid;
296 key->perm = perm;
297 key->restrict_link = restrict_link;
298 key->last_used_at = ktime_get_real_seconds();
299
300 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
301 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
302 if (flags & KEY_ALLOC_BUILT_IN)
303 key->flags |= 1 << KEY_FLAG_BUILTIN;
304 if (flags & KEY_ALLOC_UID_KEYRING)
305 key->flags |= 1 << KEY_FLAG_UID_KEYRING;
306
307#ifdef KEY_DEBUGGING
308 key->magic = KEY_DEBUG_MAGIC;
309#endif
310
311 /* let the security module know about the key */
312 ret = security_key_alloc(key, cred, flags);
313 if (ret < 0)
314 goto security_error;
315
316 /* publish the key by giving it a serial number */
317 refcount_inc(&key->domain_tag->usage);
318 atomic_inc(&user->nkeys);
319 key_alloc_serial(key);
320
321error:
322 return key;
323
324security_error:
325 kfree(key->description);
326 kmem_cache_free(key_jar, key);
327 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
328 spin_lock(&user->lock);
329 user->qnkeys--;
330 user->qnbytes -= quotalen;
331 spin_unlock(&user->lock);
332 }
333 key_user_put(user);
334 key = ERR_PTR(ret);
335 goto error;
336
337no_memory_3:
338 kmem_cache_free(key_jar, key);
339no_memory_2:
340 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
341 spin_lock(&user->lock);
342 user->qnkeys--;
343 user->qnbytes -= quotalen;
344 spin_unlock(&user->lock);
345 }
346 key_user_put(user);
347no_memory_1:
348 key = ERR_PTR(-ENOMEM);
349 goto error;
350
351no_quota:
352 spin_unlock(&user->lock);
353 key_user_put(user);
354 key = ERR_PTR(-EDQUOT);
355 goto error;
356}
357EXPORT_SYMBOL(key_alloc);
358
359/**
360 * key_payload_reserve - Adjust data quota reservation for the key's payload
361 * @key: The key to make the reservation for.
362 * @datalen: The amount of data payload the caller now wants.
363 *
364 * Adjust the amount of the owning user's key data quota that a key reserves.
365 * If the amount is increased, then -EDQUOT may be returned if there isn't
366 * enough free quota available.
367 *
368 * If successful, 0 is returned.
369 */
370int key_payload_reserve(struct key *key, size_t datalen)
371{
372 int delta = (int)datalen - key->datalen;
373 int ret = 0;
374
375 key_check(key);
376
377 /* contemplate the quota adjustment */
378 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
379 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
380 key_quota_root_maxbytes : key_quota_maxbytes;
381
382 spin_lock(&key->user->lock);
383
384 if (delta > 0 &&
385 (key->user->qnbytes + delta > maxbytes ||
386 key->user->qnbytes + delta < key->user->qnbytes)) {
387 ret = -EDQUOT;
388 }
389 else {
390 key->user->qnbytes += delta;
391 key->quotalen += delta;
392 }
393 spin_unlock(&key->user->lock);
394 }
395
396 /* change the recorded data length if that didn't generate an error */
397 if (ret == 0)
398 key->datalen = datalen;
399
400 return ret;
401}
402EXPORT_SYMBOL(key_payload_reserve);
403
404/*
405 * Change the key state to being instantiated.
406 */
407static void mark_key_instantiated(struct key *key, int reject_error)
408{
409 /* Commit the payload before setting the state; barrier versus
410 * key_read_state().
411 */
412 smp_store_release(&key->state,
413 (reject_error < 0) ? reject_error : KEY_IS_POSITIVE);
414}
415
416/*
417 * Instantiate a key and link it into the target keyring atomically. Must be
418 * called with the target keyring's semaphore writelocked. The target key's
419 * semaphore need not be locked as instantiation is serialised by
420 * key_construction_mutex.
421 */
422static int __key_instantiate_and_link(struct key *key,
423 struct key_preparsed_payload *prep,
424 struct key *keyring,
425 struct key *authkey,
426 struct assoc_array_edit **_edit)
427{
428 int ret, awaken;
429
430 key_check(key);
431 key_check(keyring);
432
433 awaken = 0;
434 ret = -EBUSY;
435
436 mutex_lock(&key_construction_mutex);
437
438 /* can't instantiate twice */
439 if (key->state == KEY_IS_UNINSTANTIATED) {
440 /* instantiate the key */
441 ret = key->type->instantiate(key, prep);
442
443 if (ret == 0) {
444 /* mark the key as being instantiated */
445 atomic_inc(&key->user->nikeys);
446 mark_key_instantiated(key, 0);
447 notify_key(key, NOTIFY_KEY_INSTANTIATED, 0);
448
449 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
450 awaken = 1;
451
452 /* and link it into the destination keyring */
453 if (keyring) {
454 if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
455 set_bit(KEY_FLAG_KEEP, &key->flags);
456
457 __key_link(keyring, key, _edit);
458 }
459
460 /* disable the authorisation key */
461 if (authkey)
462 key_invalidate(authkey);
463
464 if (prep->expiry != TIME64_MAX) {
465 key->expiry = prep->expiry;
466 key_schedule_gc(prep->expiry + key_gc_delay);
467 }
468 }
469 }
470
471 mutex_unlock(&key_construction_mutex);
472
473 /* wake up anyone waiting for a key to be constructed */
474 if (awaken)
475 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
476
477 return ret;
478}
479
480/**
481 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
482 * @key: The key to instantiate.
483 * @data: The data to use to instantiate the keyring.
484 * @datalen: The length of @data.
485 * @keyring: Keyring to create a link in on success (or NULL).
486 * @authkey: The authorisation token permitting instantiation.
487 *
488 * Instantiate a key that's in the uninstantiated state using the provided data
489 * and, if successful, link it in to the destination keyring if one is
490 * supplied.
491 *
492 * If successful, 0 is returned, the authorisation token is revoked and anyone
493 * waiting for the key is woken up. If the key was already instantiated,
494 * -EBUSY will be returned.
495 */
496int key_instantiate_and_link(struct key *key,
497 const void *data,
498 size_t datalen,
499 struct key *keyring,
500 struct key *authkey)
501{
502 struct key_preparsed_payload prep;
503 struct assoc_array_edit *edit = NULL;
504 int ret;
505
506 memset(&prep, 0, sizeof(prep));
507 prep.data = data;
508 prep.datalen = datalen;
509 prep.quotalen = key->type->def_datalen;
510 prep.expiry = TIME64_MAX;
511 if (key->type->preparse) {
512 ret = key->type->preparse(&prep);
513 if (ret < 0)
514 goto error;
515 }
516
517 if (keyring) {
518 ret = __key_link_lock(keyring, &key->index_key);
519 if (ret < 0)
520 goto error;
521
522 ret = __key_link_begin(keyring, &key->index_key, &edit);
523 if (ret < 0)
524 goto error_link_end;
525
526 if (keyring->restrict_link && keyring->restrict_link->check) {
527 struct key_restriction *keyres = keyring->restrict_link;
528
529 ret = keyres->check(keyring, key->type, &prep.payload,
530 keyres->key);
531 if (ret < 0)
532 goto error_link_end;
533 }
534 }
535
536 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
537
538error_link_end:
539 if (keyring)
540 __key_link_end(keyring, &key->index_key, edit);
541
542error:
543 if (key->type->preparse)
544 key->type->free_preparse(&prep);
545 return ret;
546}
547
548EXPORT_SYMBOL(key_instantiate_and_link);
549
550/**
551 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
552 * @key: The key to instantiate.
553 * @timeout: The timeout on the negative key.
554 * @error: The error to return when the key is hit.
555 * @keyring: Keyring to create a link in on success (or NULL).
556 * @authkey: The authorisation token permitting instantiation.
557 *
558 * Negatively instantiate a key that's in the uninstantiated state and, if
559 * successful, set its timeout and stored error and link it in to the
560 * destination keyring if one is supplied. The key and any links to the key
561 * will be automatically garbage collected after the timeout expires.
562 *
563 * Negative keys are used to rate limit repeated request_key() calls by causing
564 * them to return the stored error code (typically ENOKEY) until the negative
565 * key expires.
566 *
567 * If successful, 0 is returned, the authorisation token is revoked and anyone
568 * waiting for the key is woken up. If the key was already instantiated,
569 * -EBUSY will be returned.
570 */
571int key_reject_and_link(struct key *key,
572 unsigned timeout,
573 unsigned error,
574 struct key *keyring,
575 struct key *authkey)
576{
577 struct assoc_array_edit *edit = NULL;
578 int ret, awaken, link_ret = 0;
579
580 key_check(key);
581 key_check(keyring);
582
583 awaken = 0;
584 ret = -EBUSY;
585
586 if (keyring) {
587 if (keyring->restrict_link)
588 return -EPERM;
589
590 link_ret = __key_link_lock(keyring, &key->index_key);
591 if (link_ret == 0) {
592 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
593 if (link_ret < 0)
594 __key_link_end(keyring, &key->index_key, edit);
595 }
596 }
597
598 mutex_lock(&key_construction_mutex);
599
600 /* can't instantiate twice */
601 if (key->state == KEY_IS_UNINSTANTIATED) {
602 /* mark the key as being negatively instantiated */
603 atomic_inc(&key->user->nikeys);
604 mark_key_instantiated(key, -error);
605 notify_key(key, NOTIFY_KEY_INSTANTIATED, -error);
606 key->expiry = ktime_get_real_seconds() + timeout;
607 key_schedule_gc(key->expiry + key_gc_delay);
608
609 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
610 awaken = 1;
611
612 ret = 0;
613
614 /* and link it into the destination keyring */
615 if (keyring && link_ret == 0)
616 __key_link(keyring, key, &edit);
617
618 /* disable the authorisation key */
619 if (authkey)
620 key_invalidate(authkey);
621 }
622
623 mutex_unlock(&key_construction_mutex);
624
625 if (keyring && link_ret == 0)
626 __key_link_end(keyring, &key->index_key, edit);
627
628 /* wake up anyone waiting for a key to be constructed */
629 if (awaken)
630 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
631
632 return ret == 0 ? link_ret : ret;
633}
634EXPORT_SYMBOL(key_reject_and_link);
635
636/**
637 * key_put - Discard a reference to a key.
638 * @key: The key to discard a reference from.
639 *
640 * Discard a reference to a key, and when all the references are gone, we
641 * schedule the cleanup task to come and pull it out of the tree in process
642 * context at some later time.
643 */
644void key_put(struct key *key)
645{
646 if (key) {
647 key_check(key);
648
649 if (refcount_dec_and_test(&key->usage))
650 schedule_work(&key_gc_work);
651 }
652}
653EXPORT_SYMBOL(key_put);
654
655/*
656 * Find a key by its serial number.
657 */
658struct key *key_lookup(key_serial_t id)
659{
660 struct rb_node *n;
661 struct key *key;
662
663 spin_lock(&key_serial_lock);
664
665 /* search the tree for the specified key */
666 n = key_serial_tree.rb_node;
667 while (n) {
668 key = rb_entry(n, struct key, serial_node);
669
670 if (id < key->serial)
671 n = n->rb_left;
672 else if (id > key->serial)
673 n = n->rb_right;
674 else
675 goto found;
676 }
677
678not_found:
679 key = ERR_PTR(-ENOKEY);
680 goto error;
681
682found:
683 /* A key is allowed to be looked up only if someone still owns a
684 * reference to it - otherwise it's awaiting the gc.
685 */
686 if (!refcount_inc_not_zero(&key->usage))
687 goto not_found;
688
689error:
690 spin_unlock(&key_serial_lock);
691 return key;
692}
693
694/*
695 * Find and lock the specified key type against removal.
696 *
697 * We return with the sem read-locked if successful. If the type wasn't
698 * available -ENOKEY is returned instead.
699 */
700struct key_type *key_type_lookup(const char *type)
701{
702 struct key_type *ktype;
703
704 down_read(&key_types_sem);
705
706 /* look up the key type to see if it's one of the registered kernel
707 * types */
708 list_for_each_entry(ktype, &key_types_list, link) {
709 if (strcmp(ktype->name, type) == 0)
710 goto found_kernel_type;
711 }
712
713 up_read(&key_types_sem);
714 ktype = ERR_PTR(-ENOKEY);
715
716found_kernel_type:
717 return ktype;
718}
719
720void key_set_timeout(struct key *key, unsigned timeout)
721{
722 time64_t expiry = 0;
723
724 /* make the changes with the locks held to prevent races */
725 down_write(&key->sem);
726
727 if (timeout > 0)
728 expiry = ktime_get_real_seconds() + timeout;
729
730 key->expiry = expiry;
731 key_schedule_gc(key->expiry + key_gc_delay);
732
733 up_write(&key->sem);
734}
735EXPORT_SYMBOL_GPL(key_set_timeout);
736
737/*
738 * Unlock a key type locked by key_type_lookup().
739 */
740void key_type_put(struct key_type *ktype)
741{
742 up_read(&key_types_sem);
743}
744
745/*
746 * Attempt to update an existing key.
747 *
748 * The key is given to us with an incremented refcount that we need to discard
749 * if we get an error.
750 */
751static inline key_ref_t __key_update(key_ref_t key_ref,
752 struct key_preparsed_payload *prep)
753{
754 struct key *key = key_ref_to_ptr(key_ref);
755 int ret;
756
757 /* need write permission on the key to update it */
758 ret = key_permission(key_ref, KEY_NEED_WRITE);
759 if (ret < 0)
760 goto error;
761
762 ret = -EEXIST;
763 if (!key->type->update)
764 goto error;
765
766 down_write(&key->sem);
767
768 ret = key->type->update(key, prep);
769 if (ret == 0) {
770 /* Updating a negative key positively instantiates it */
771 mark_key_instantiated(key, 0);
772 notify_key(key, NOTIFY_KEY_UPDATED, 0);
773 }
774
775 up_write(&key->sem);
776
777 if (ret < 0)
778 goto error;
779out:
780 return key_ref;
781
782error:
783 key_put(key);
784 key_ref = ERR_PTR(ret);
785 goto out;
786}
787
788/**
789 * key_create_or_update - Update or create and instantiate a key.
790 * @keyring_ref: A pointer to the destination keyring with possession flag.
791 * @type: The type of key.
792 * @description: The searchable description for the key.
793 * @payload: The data to use to instantiate or update the key.
794 * @plen: The length of @payload.
795 * @perm: The permissions mask for a new key.
796 * @flags: The quota flags for a new key.
797 *
798 * Search the destination keyring for a key of the same description and if one
799 * is found, update it, otherwise create and instantiate a new one and create a
800 * link to it from that keyring.
801 *
802 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
803 * concocted.
804 *
805 * Returns a pointer to the new key if successful, -ENODEV if the key type
806 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
807 * caller isn't permitted to modify the keyring or the LSM did not permit
808 * creation of the key.
809 *
810 * On success, the possession flag from the keyring ref will be tacked on to
811 * the key ref before it is returned.
812 */
813key_ref_t key_create_or_update(key_ref_t keyring_ref,
814 const char *type,
815 const char *description,
816 const void *payload,
817 size_t plen,
818 key_perm_t perm,
819 unsigned long flags)
820{
821 struct keyring_index_key index_key = {
822 .description = description,
823 };
824 struct key_preparsed_payload prep;
825 struct assoc_array_edit *edit = NULL;
826 const struct cred *cred = current_cred();
827 struct key *keyring, *key = NULL;
828 key_ref_t key_ref;
829 int ret;
830 struct key_restriction *restrict_link = NULL;
831
832 /* look up the key type to see if it's one of the registered kernel
833 * types */
834 index_key.type = key_type_lookup(type);
835 if (IS_ERR(index_key.type)) {
836 key_ref = ERR_PTR(-ENODEV);
837 goto error;
838 }
839
840 key_ref = ERR_PTR(-EINVAL);
841 if (!index_key.type->instantiate ||
842 (!index_key.description && !index_key.type->preparse))
843 goto error_put_type;
844
845 keyring = key_ref_to_ptr(keyring_ref);
846
847 key_check(keyring);
848
849 if (!(flags & KEY_ALLOC_BYPASS_RESTRICTION))
850 restrict_link = keyring->restrict_link;
851
852 key_ref = ERR_PTR(-ENOTDIR);
853 if (keyring->type != &key_type_keyring)
854 goto error_put_type;
855
856 memset(&prep, 0, sizeof(prep));
857 prep.data = payload;
858 prep.datalen = plen;
859 prep.quotalen = index_key.type->def_datalen;
860 prep.expiry = TIME64_MAX;
861 if (index_key.type->preparse) {
862 ret = index_key.type->preparse(&prep);
863 if (ret < 0) {
864 key_ref = ERR_PTR(ret);
865 goto error_free_prep;
866 }
867 if (!index_key.description)
868 index_key.description = prep.description;
869 key_ref = ERR_PTR(-EINVAL);
870 if (!index_key.description)
871 goto error_free_prep;
872 }
873 index_key.desc_len = strlen(index_key.description);
874 key_set_index_key(&index_key);
875
876 ret = __key_link_lock(keyring, &index_key);
877 if (ret < 0) {
878 key_ref = ERR_PTR(ret);
879 goto error_free_prep;
880 }
881
882 ret = __key_link_begin(keyring, &index_key, &edit);
883 if (ret < 0) {
884 key_ref = ERR_PTR(ret);
885 goto error_link_end;
886 }
887
888 if (restrict_link && restrict_link->check) {
889 ret = restrict_link->check(keyring, index_key.type,
890 &prep.payload, restrict_link->key);
891 if (ret < 0) {
892 key_ref = ERR_PTR(ret);
893 goto error_link_end;
894 }
895 }
896
897 /* if we're going to allocate a new key, we're going to have
898 * to modify the keyring */
899 ret = key_permission(keyring_ref, KEY_NEED_WRITE);
900 if (ret < 0) {
901 key_ref = ERR_PTR(ret);
902 goto error_link_end;
903 }
904
905 /* if it's possible to update this type of key, search for an existing
906 * key of the same type and description in the destination keyring and
907 * update that instead if possible
908 */
909 if (index_key.type->update) {
910 key_ref = find_key_to_update(keyring_ref, &index_key);
911 if (key_ref)
912 goto found_matching_key;
913 }
914
915 /* if the client doesn't provide, decide on the permissions we want */
916 if (perm == KEY_PERM_UNDEF) {
917 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
918 perm |= KEY_USR_VIEW;
919
920 if (index_key.type->read)
921 perm |= KEY_POS_READ;
922
923 if (index_key.type == &key_type_keyring ||
924 index_key.type->update)
925 perm |= KEY_POS_WRITE;
926 }
927
928 /* allocate a new key */
929 key = key_alloc(index_key.type, index_key.description,
930 cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
931 if (IS_ERR(key)) {
932 key_ref = ERR_CAST(key);
933 goto error_link_end;
934 }
935
936 /* instantiate it and link it into the target keyring */
937 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
938 if (ret < 0) {
939 key_put(key);
940 key_ref = ERR_PTR(ret);
941 goto error_link_end;
942 }
943
944 ima_post_key_create_or_update(keyring, key, payload, plen,
945 flags, true);
946
947 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
948
949error_link_end:
950 __key_link_end(keyring, &index_key, edit);
951error_free_prep:
952 if (index_key.type->preparse)
953 index_key.type->free_preparse(&prep);
954error_put_type:
955 key_type_put(index_key.type);
956error:
957 return key_ref;
958
959 found_matching_key:
960 /* we found a matching key, so we're going to try to update it
961 * - we can drop the locks first as we have the key pinned
962 */
963 __key_link_end(keyring, &index_key, edit);
964
965 key = key_ref_to_ptr(key_ref);
966 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) {
967 ret = wait_for_key_construction(key, true);
968 if (ret < 0) {
969 key_ref_put(key_ref);
970 key_ref = ERR_PTR(ret);
971 goto error_free_prep;
972 }
973 }
974
975 key_ref = __key_update(key_ref, &prep);
976
977 if (!IS_ERR(key_ref))
978 ima_post_key_create_or_update(keyring, key,
979 payload, plen,
980 flags, false);
981
982 goto error_free_prep;
983}
984EXPORT_SYMBOL(key_create_or_update);
985
986/**
987 * key_update - Update a key's contents.
988 * @key_ref: The pointer (plus possession flag) to the key.
989 * @payload: The data to be used to update the key.
990 * @plen: The length of @payload.
991 *
992 * Attempt to update the contents of a key with the given payload data. The
993 * caller must be granted Write permission on the key. Negative keys can be
994 * instantiated by this method.
995 *
996 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
997 * type does not support updating. The key type may return other errors.
998 */
999int key_update(key_ref_t key_ref, const void *payload, size_t plen)
1000{
1001 struct key_preparsed_payload prep;
1002 struct key *key = key_ref_to_ptr(key_ref);
1003 int ret;
1004
1005 key_check(key);
1006
1007 /* the key must be writable */
1008 ret = key_permission(key_ref, KEY_NEED_WRITE);
1009 if (ret < 0)
1010 return ret;
1011
1012 /* attempt to update it if supported */
1013 if (!key->type->update)
1014 return -EOPNOTSUPP;
1015
1016 memset(&prep, 0, sizeof(prep));
1017 prep.data = payload;
1018 prep.datalen = plen;
1019 prep.quotalen = key->type->def_datalen;
1020 prep.expiry = TIME64_MAX;
1021 if (key->type->preparse) {
1022 ret = key->type->preparse(&prep);
1023 if (ret < 0)
1024 goto error;
1025 }
1026
1027 down_write(&key->sem);
1028
1029 ret = key->type->update(key, &prep);
1030 if (ret == 0) {
1031 /* Updating a negative key positively instantiates it */
1032 mark_key_instantiated(key, 0);
1033 notify_key(key, NOTIFY_KEY_UPDATED, 0);
1034 }
1035
1036 up_write(&key->sem);
1037
1038error:
1039 if (key->type->preparse)
1040 key->type->free_preparse(&prep);
1041 return ret;
1042}
1043EXPORT_SYMBOL(key_update);
1044
1045/**
1046 * key_revoke - Revoke a key.
1047 * @key: The key to be revoked.
1048 *
1049 * Mark a key as being revoked and ask the type to free up its resources. The
1050 * revocation timeout is set and the key and all its links will be
1051 * automatically garbage collected after key_gc_delay amount of time if they
1052 * are not manually dealt with first.
1053 */
1054void key_revoke(struct key *key)
1055{
1056 time64_t time;
1057
1058 key_check(key);
1059
1060 /* make sure no one's trying to change or use the key when we mark it
1061 * - we tell lockdep that we might nest because we might be revoking an
1062 * authorisation key whilst holding the sem on a key we've just
1063 * instantiated
1064 */
1065 down_write_nested(&key->sem, 1);
1066 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags)) {
1067 notify_key(key, NOTIFY_KEY_REVOKED, 0);
1068 if (key->type->revoke)
1069 key->type->revoke(key);
1070
1071 /* set the death time to no more than the expiry time */
1072 time = ktime_get_real_seconds();
1073 if (key->revoked_at == 0 || key->revoked_at > time) {
1074 key->revoked_at = time;
1075 key_schedule_gc(key->revoked_at + key_gc_delay);
1076 }
1077 }
1078
1079 up_write(&key->sem);
1080}
1081EXPORT_SYMBOL(key_revoke);
1082
1083/**
1084 * key_invalidate - Invalidate a key.
1085 * @key: The key to be invalidated.
1086 *
1087 * Mark a key as being invalidated and have it cleaned up immediately. The key
1088 * is ignored by all searches and other operations from this point.
1089 */
1090void key_invalidate(struct key *key)
1091{
1092 kenter("%d", key_serial(key));
1093
1094 key_check(key);
1095
1096 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1097 down_write_nested(&key->sem, 1);
1098 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1099 notify_key(key, NOTIFY_KEY_INVALIDATED, 0);
1100 key_schedule_gc_links();
1101 }
1102 up_write(&key->sem);
1103 }
1104}
1105EXPORT_SYMBOL(key_invalidate);
1106
1107/**
1108 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1109 * @key: The key to be instantiated
1110 * @prep: The preparsed data to load.
1111 *
1112 * Instantiate a key from preparsed data. We assume we can just copy the data
1113 * in directly and clear the old pointers.
1114 *
1115 * This can be pointed to directly by the key type instantiate op pointer.
1116 */
1117int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1118{
1119 int ret;
1120
1121 pr_devel("==>%s()\n", __func__);
1122
1123 ret = key_payload_reserve(key, prep->quotalen);
1124 if (ret == 0) {
1125 rcu_assign_keypointer(key, prep->payload.data[0]);
1126 key->payload.data[1] = prep->payload.data[1];
1127 key->payload.data[2] = prep->payload.data[2];
1128 key->payload.data[3] = prep->payload.data[3];
1129 prep->payload.data[0] = NULL;
1130 prep->payload.data[1] = NULL;
1131 prep->payload.data[2] = NULL;
1132 prep->payload.data[3] = NULL;
1133 }
1134 pr_devel("<==%s() = %d\n", __func__, ret);
1135 return ret;
1136}
1137EXPORT_SYMBOL(generic_key_instantiate);
1138
1139/**
1140 * register_key_type - Register a type of key.
1141 * @ktype: The new key type.
1142 *
1143 * Register a new key type.
1144 *
1145 * Returns 0 on success or -EEXIST if a type of this name already exists.
1146 */
1147int register_key_type(struct key_type *ktype)
1148{
1149 struct key_type *p;
1150 int ret;
1151
1152 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1153
1154 ret = -EEXIST;
1155 down_write(&key_types_sem);
1156
1157 /* disallow key types with the same name */
1158 list_for_each_entry(p, &key_types_list, link) {
1159 if (strcmp(p->name, ktype->name) == 0)
1160 goto out;
1161 }
1162
1163 /* store the type */
1164 list_add(&ktype->link, &key_types_list);
1165
1166 pr_notice("Key type %s registered\n", ktype->name);
1167 ret = 0;
1168
1169out:
1170 up_write(&key_types_sem);
1171 return ret;
1172}
1173EXPORT_SYMBOL(register_key_type);
1174
1175/**
1176 * unregister_key_type - Unregister a type of key.
1177 * @ktype: The key type.
1178 *
1179 * Unregister a key type and mark all the extant keys of this type as dead.
1180 * Those keys of this type are then destroyed to get rid of their payloads and
1181 * they and their links will be garbage collected as soon as possible.
1182 */
1183void unregister_key_type(struct key_type *ktype)
1184{
1185 down_write(&key_types_sem);
1186 list_del_init(&ktype->link);
1187 downgrade_write(&key_types_sem);
1188 key_gc_keytype(ktype);
1189 pr_notice("Key type %s unregistered\n", ktype->name);
1190 up_read(&key_types_sem);
1191}
1192EXPORT_SYMBOL(unregister_key_type);
1193
1194/*
1195 * Initialise the key management state.
1196 */
1197void __init key_init(void)
1198{
1199 /* allocate a slab in which we can store keys */
1200 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1201 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1202
1203 /* add the special key types */
1204 list_add_tail(&key_type_keyring.link, &key_types_list);
1205 list_add_tail(&key_type_dead.link, &key_types_list);
1206 list_add_tail(&key_type_user.link, &key_types_list);
1207 list_add_tail(&key_type_logon.link, &key_types_list);
1208
1209 /* record the root user tracking */
1210 rb_link_node(&root_key_user.node,
1211 NULL,
1212 &key_user_tree.rb_node);
1213
1214 rb_insert_color(&root_key_user.node,
1215 &key_user_tree);
1216}
1/* 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 <linux/user_namespace.h>
22#include "internal.h"
23
24struct kmem_cache *key_jar;
25struct rb_root key_serial_tree; /* tree of keys indexed by serial */
26DEFINE_SPINLOCK(key_serial_lock);
27
28struct rb_root key_user_tree; /* tree of quota records indexed by UID */
29DEFINE_SPINLOCK(key_user_lock);
30
31unsigned int key_quota_root_maxkeys = 200; /* root's key count quota */
32unsigned int key_quota_root_maxbytes = 20000; /* root's key space quota */
33unsigned int key_quota_maxkeys = 200; /* general key count quota */
34unsigned int key_quota_maxbytes = 20000; /* general key space quota */
35
36static LIST_HEAD(key_types_list);
37static DECLARE_RWSEM(key_types_sem);
38
39/* We serialise key instantiation and link */
40DEFINE_MUTEX(key_construction_mutex);
41
42#ifdef KEY_DEBUGGING
43void __key_check(const struct key *key)
44{
45 printk("__key_check: key %p {%08x} should be {%08x}\n",
46 key, key->magic, KEY_DEBUG_MAGIC);
47 BUG();
48}
49#endif
50
51/*
52 * Get the key quota record for a user, allocating a new record if one doesn't
53 * already exist.
54 */
55struct key_user *key_user_lookup(uid_t uid, struct user_namespace *user_ns)
56{
57 struct key_user *candidate = NULL, *user;
58 struct rb_node *parent = NULL;
59 struct rb_node **p;
60
61try_again:
62 p = &key_user_tree.rb_node;
63 spin_lock(&key_user_lock);
64
65 /* search the tree for a user record with a matching UID */
66 while (*p) {
67 parent = *p;
68 user = rb_entry(parent, struct key_user, node);
69
70 if (uid < user->uid)
71 p = &(*p)->rb_left;
72 else if (uid > user->uid)
73 p = &(*p)->rb_right;
74 else if (user_ns < user->user_ns)
75 p = &(*p)->rb_left;
76 else if (user_ns > user->user_ns)
77 p = &(*p)->rb_right;
78 else
79 goto found;
80 }
81
82 /* if we get here, we failed to find a match in the tree */
83 if (!candidate) {
84 /* allocate a candidate user record if we don't already have
85 * one */
86 spin_unlock(&key_user_lock);
87
88 user = NULL;
89 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
90 if (unlikely(!candidate))
91 goto out;
92
93 /* the allocation may have scheduled, so we need to repeat the
94 * search lest someone else added the record whilst we were
95 * asleep */
96 goto try_again;
97 }
98
99 /* if we get here, then the user record still hadn't appeared on the
100 * second pass - so we use the candidate record */
101 atomic_set(&candidate->usage, 1);
102 atomic_set(&candidate->nkeys, 0);
103 atomic_set(&candidate->nikeys, 0);
104 candidate->uid = uid;
105 candidate->user_ns = get_user_ns(user_ns);
106 candidate->qnkeys = 0;
107 candidate->qnbytes = 0;
108 spin_lock_init(&candidate->lock);
109 mutex_init(&candidate->cons_lock);
110
111 rb_link_node(&candidate->node, parent, p);
112 rb_insert_color(&candidate->node, &key_user_tree);
113 spin_unlock(&key_user_lock);
114 user = candidate;
115 goto out;
116
117 /* okay - we found a user record for this UID */
118found:
119 atomic_inc(&user->usage);
120 spin_unlock(&key_user_lock);
121 kfree(candidate);
122out:
123 return user;
124}
125
126/*
127 * Dispose of a user structure
128 */
129void key_user_put(struct key_user *user)
130{
131 if (atomic_dec_and_lock(&user->usage, &key_user_lock)) {
132 rb_erase(&user->node, &key_user_tree);
133 spin_unlock(&key_user_lock);
134 put_user_ns(user->user_ns);
135
136 kfree(user);
137 }
138}
139
140/*
141 * Allocate a serial number for a key. These are assigned randomly to avoid
142 * security issues through covert channel problems.
143 */
144static inline void key_alloc_serial(struct key *key)
145{
146 struct rb_node *parent, **p;
147 struct key *xkey;
148
149 /* propose a random serial number and look for a hole for it in the
150 * serial number tree */
151 do {
152 get_random_bytes(&key->serial, sizeof(key->serial));
153
154 key->serial >>= 1; /* negative numbers are not permitted */
155 } while (key->serial < 3);
156
157 spin_lock(&key_serial_lock);
158
159attempt_insertion:
160 parent = NULL;
161 p = &key_serial_tree.rb_node;
162
163 while (*p) {
164 parent = *p;
165 xkey = rb_entry(parent, struct key, serial_node);
166
167 if (key->serial < xkey->serial)
168 p = &(*p)->rb_left;
169 else if (key->serial > xkey->serial)
170 p = &(*p)->rb_right;
171 else
172 goto serial_exists;
173 }
174
175 /* we've found a suitable hole - arrange for this key to occupy it */
176 rb_link_node(&key->serial_node, parent, p);
177 rb_insert_color(&key->serial_node, &key_serial_tree);
178
179 spin_unlock(&key_serial_lock);
180 return;
181
182 /* we found a key with the proposed serial number - walk the tree from
183 * that point looking for the next unused serial number */
184serial_exists:
185 for (;;) {
186 key->serial++;
187 if (key->serial < 3) {
188 key->serial = 3;
189 goto attempt_insertion;
190 }
191
192 parent = rb_next(parent);
193 if (!parent)
194 goto attempt_insertion;
195
196 xkey = rb_entry(parent, struct key, serial_node);
197 if (key->serial < xkey->serial)
198 goto attempt_insertion;
199 }
200}
201
202/**
203 * key_alloc - Allocate a key of the specified type.
204 * @type: The type of key to allocate.
205 * @desc: The key description to allow the key to be searched out.
206 * @uid: The owner of the new key.
207 * @gid: The group ID for the new key's group permissions.
208 * @cred: The credentials specifying UID namespace.
209 * @perm: The permissions mask of the new key.
210 * @flags: Flags specifying quota properties.
211 *
212 * Allocate a key of the specified type with the attributes given. The key is
213 * returned in an uninstantiated state and the caller needs to instantiate the
214 * key before returning.
215 *
216 * The user's key count quota is updated to reflect the creation of the key and
217 * the user's key data quota has the default for the key type reserved. The
218 * instantiation function should amend this as necessary. If insufficient
219 * quota is available, -EDQUOT will be returned.
220 *
221 * The LSM security modules can prevent a key being created, in which case
222 * -EACCES will be returned.
223 *
224 * Returns a pointer to the new key if successful and an error code otherwise.
225 *
226 * Note that the caller needs to ensure the key type isn't uninstantiated.
227 * Internally this can be done by locking key_types_sem. Externally, this can
228 * be done by either never unregistering the key type, or making sure
229 * key_alloc() calls don't race with module unloading.
230 */
231struct key *key_alloc(struct key_type *type, const char *desc,
232 uid_t uid, gid_t gid, const struct cred *cred,
233 key_perm_t perm, unsigned long flags)
234{
235 struct key_user *user = NULL;
236 struct key *key;
237 size_t desclen, quotalen;
238 int ret;
239
240 key = ERR_PTR(-EINVAL);
241 if (!desc || !*desc)
242 goto error;
243
244 if (type->vet_description) {
245 ret = type->vet_description(desc);
246 if (ret < 0) {
247 key = ERR_PTR(ret);
248 goto error;
249 }
250 }
251
252 desclen = strlen(desc) + 1;
253 quotalen = desclen + type->def_datalen;
254
255 /* get hold of the key tracking for this user */
256 user = key_user_lookup(uid, cred->user_ns);
257 if (!user)
258 goto no_memory_1;
259
260 /* check that the user's quota permits allocation of another key and
261 * its description */
262 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
263 unsigned maxkeys = (uid == 0) ?
264 key_quota_root_maxkeys : key_quota_maxkeys;
265 unsigned maxbytes = (uid == 0) ?
266 key_quota_root_maxbytes : key_quota_maxbytes;
267
268 spin_lock(&user->lock);
269 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
270 if (user->qnkeys + 1 >= maxkeys ||
271 user->qnbytes + quotalen >= maxbytes ||
272 user->qnbytes + quotalen < user->qnbytes)
273 goto no_quota;
274 }
275
276 user->qnkeys++;
277 user->qnbytes += quotalen;
278 spin_unlock(&user->lock);
279 }
280
281 /* allocate and initialise the key and its description */
282 key = kmem_cache_alloc(key_jar, GFP_KERNEL);
283 if (!key)
284 goto no_memory_2;
285
286 if (desc) {
287 key->description = kmemdup(desc, desclen, GFP_KERNEL);
288 if (!key->description)
289 goto no_memory_3;
290 }
291
292 atomic_set(&key->usage, 1);
293 init_rwsem(&key->sem);
294 lockdep_set_class(&key->sem, &type->lock_class);
295 key->type = type;
296 key->user = user;
297 key->quotalen = quotalen;
298 key->datalen = type->def_datalen;
299 key->uid = uid;
300 key->gid = gid;
301 key->perm = perm;
302 key->flags = 0;
303 key->expiry = 0;
304 key->payload.data = NULL;
305 key->security = NULL;
306
307 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
308 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
309
310 memset(&key->type_data, 0, sizeof(key->type_data));
311
312#ifdef KEY_DEBUGGING
313 key->magic = KEY_DEBUG_MAGIC;
314#endif
315
316 /* let the security module know about the key */
317 ret = security_key_alloc(key, cred, flags);
318 if (ret < 0)
319 goto security_error;
320
321 /* publish the key by giving it a serial number */
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(&user->lock);
333 user->qnkeys--;
334 user->qnbytes -= quotalen;
335 spin_unlock(&user->lock);
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(&user->lock);
346 user->qnkeys--;
347 user->qnbytes -= quotalen;
348 spin_unlock(&user->lock);
349 }
350 key_user_put(user);
351no_memory_1:
352 key = ERR_PTR(-ENOMEM);
353 goto error;
354
355no_quota:
356 spin_unlock(&user->lock);
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 = (key->user->uid == 0) ?
384 key_quota_root_maxbytes : key_quota_maxbytes;
385
386 spin_lock(&key->user->lock);
387
388 if (delta > 0 &&
389 (key->user->qnbytes + delta >= maxbytes ||
390 key->user->qnbytes + delta < key->user->qnbytes)) {
391 ret = -EDQUOT;
392 }
393 else {
394 key->user->qnbytes += delta;
395 key->quotalen += delta;
396 }
397 spin_unlock(&key->user->lock);
398 }
399
400 /* change the recorded data length if that didn't generate an error */
401 if (ret == 0)
402 key->datalen = datalen;
403
404 return ret;
405}
406EXPORT_SYMBOL(key_payload_reserve);
407
408/*
409 * Instantiate a key and link it into the target keyring atomically. Must be
410 * called with the target keyring's semaphore writelocked. The target key's
411 * semaphore need not be locked as instantiation is serialised by
412 * key_construction_mutex.
413 */
414static int __key_instantiate_and_link(struct key *key,
415 const void *data,
416 size_t datalen,
417 struct key *keyring,
418 struct key *authkey,
419 unsigned long *_prealloc)
420{
421 int ret, awaken;
422
423 key_check(key);
424 key_check(keyring);
425
426 awaken = 0;
427 ret = -EBUSY;
428
429 mutex_lock(&key_construction_mutex);
430
431 /* can't instantiate twice */
432 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
433 /* instantiate the key */
434 ret = key->type->instantiate(key, data, datalen);
435
436 if (ret == 0) {
437 /* mark the key as being instantiated */
438 atomic_inc(&key->user->nikeys);
439 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
440
441 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
442 awaken = 1;
443
444 /* and link it into the destination keyring */
445 if (keyring)
446 __key_link(keyring, key, _prealloc);
447
448 /* disable the authorisation key */
449 if (authkey)
450 key_revoke(authkey);
451 }
452 }
453
454 mutex_unlock(&key_construction_mutex);
455
456 /* wake up anyone waiting for a key to be constructed */
457 if (awaken)
458 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
459
460 return ret;
461}
462
463/**
464 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
465 * @key: The key to instantiate.
466 * @data: The data to use to instantiate the keyring.
467 * @datalen: The length of @data.
468 * @keyring: Keyring to create a link in on success (or NULL).
469 * @authkey: The authorisation token permitting instantiation.
470 *
471 * Instantiate a key that's in the uninstantiated state using the provided data
472 * and, if successful, link it in to the destination keyring if one is
473 * supplied.
474 *
475 * If successful, 0 is returned, the authorisation token is revoked and anyone
476 * waiting for the key is woken up. If the key was already instantiated,
477 * -EBUSY will be returned.
478 */
479int key_instantiate_and_link(struct key *key,
480 const void *data,
481 size_t datalen,
482 struct key *keyring,
483 struct key *authkey)
484{
485 unsigned long prealloc;
486 int ret;
487
488 if (keyring) {
489 ret = __key_link_begin(keyring, key->type, key->description,
490 &prealloc);
491 if (ret < 0)
492 return ret;
493 }
494
495 ret = __key_instantiate_and_link(key, data, datalen, keyring, authkey,
496 &prealloc);
497
498 if (keyring)
499 __key_link_end(keyring, key->type, prealloc);
500
501 return ret;
502}
503
504EXPORT_SYMBOL(key_instantiate_and_link);
505
506/**
507 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
508 * @key: The key to instantiate.
509 * @timeout: The timeout on the negative key.
510 * @error: The error to return when the key is hit.
511 * @keyring: Keyring to create a link in on success (or NULL).
512 * @authkey: The authorisation token permitting instantiation.
513 *
514 * Negatively instantiate a key that's in the uninstantiated state and, if
515 * successful, set its timeout and stored error and link it in to the
516 * destination keyring if one is supplied. The key and any links to the key
517 * will be automatically garbage collected after the timeout expires.
518 *
519 * Negative keys are used to rate limit repeated request_key() calls by causing
520 * them to return the stored error code (typically ENOKEY) until the negative
521 * key expires.
522 *
523 * If successful, 0 is returned, the authorisation token is revoked and anyone
524 * waiting for the key is woken up. If the key was already instantiated,
525 * -EBUSY will be returned.
526 */
527int key_reject_and_link(struct key *key,
528 unsigned timeout,
529 unsigned error,
530 struct key *keyring,
531 struct key *authkey)
532{
533 unsigned long prealloc;
534 struct timespec now;
535 int ret, awaken, link_ret = 0;
536
537 key_check(key);
538 key_check(keyring);
539
540 awaken = 0;
541 ret = -EBUSY;
542
543 if (keyring)
544 link_ret = __key_link_begin(keyring, key->type,
545 key->description, &prealloc);
546
547 mutex_lock(&key_construction_mutex);
548
549 /* can't instantiate twice */
550 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
551 /* mark the key as being negatively instantiated */
552 atomic_inc(&key->user->nikeys);
553 set_bit(KEY_FLAG_NEGATIVE, &key->flags);
554 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
555 key->type_data.reject_error = -error;
556 now = current_kernel_time();
557 key->expiry = now.tv_sec + timeout;
558 key_schedule_gc(key->expiry + key_gc_delay);
559
560 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
561 awaken = 1;
562
563 ret = 0;
564
565 /* and link it into the destination keyring */
566 if (keyring && link_ret == 0)
567 __key_link(keyring, key, &prealloc);
568
569 /* disable the authorisation key */
570 if (authkey)
571 key_revoke(authkey);
572 }
573
574 mutex_unlock(&key_construction_mutex);
575
576 if (keyring)
577 __key_link_end(keyring, key->type, prealloc);
578
579 /* wake up anyone waiting for a key to be constructed */
580 if (awaken)
581 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
582
583 return ret == 0 ? link_ret : ret;
584}
585EXPORT_SYMBOL(key_reject_and_link);
586
587/**
588 * key_put - Discard a reference to a key.
589 * @key: The key to discard a reference from.
590 *
591 * Discard a reference to a key, and when all the references are gone, we
592 * schedule the cleanup task to come and pull it out of the tree in process
593 * context at some later time.
594 */
595void key_put(struct key *key)
596{
597 if (key) {
598 key_check(key);
599
600 if (atomic_dec_and_test(&key->usage))
601 queue_work(system_nrt_wq, &key_gc_work);
602 }
603}
604EXPORT_SYMBOL(key_put);
605
606/*
607 * Find a key by its serial number.
608 */
609struct key *key_lookup(key_serial_t id)
610{
611 struct rb_node *n;
612 struct key *key;
613
614 spin_lock(&key_serial_lock);
615
616 /* search the tree for the specified key */
617 n = key_serial_tree.rb_node;
618 while (n) {
619 key = rb_entry(n, struct key, serial_node);
620
621 if (id < key->serial)
622 n = n->rb_left;
623 else if (id > key->serial)
624 n = n->rb_right;
625 else
626 goto found;
627 }
628
629not_found:
630 key = ERR_PTR(-ENOKEY);
631 goto error;
632
633found:
634 /* pretend it doesn't exist if it is awaiting deletion */
635 if (atomic_read(&key->usage) == 0)
636 goto not_found;
637
638 /* this races with key_put(), but that doesn't matter since key_put()
639 * doesn't actually change the key
640 */
641 atomic_inc(&key->usage);
642
643error:
644 spin_unlock(&key_serial_lock);
645 return key;
646}
647
648/*
649 * Find and lock the specified key type against removal.
650 *
651 * We return with the sem read-locked if successful. If the type wasn't
652 * available -ENOKEY is returned instead.
653 */
654struct key_type *key_type_lookup(const char *type)
655{
656 struct key_type *ktype;
657
658 down_read(&key_types_sem);
659
660 /* look up the key type to see if it's one of the registered kernel
661 * types */
662 list_for_each_entry(ktype, &key_types_list, link) {
663 if (strcmp(ktype->name, type) == 0)
664 goto found_kernel_type;
665 }
666
667 up_read(&key_types_sem);
668 ktype = ERR_PTR(-ENOKEY);
669
670found_kernel_type:
671 return ktype;
672}
673
674void key_set_timeout(struct key *key, unsigned timeout)
675{
676 struct timespec now;
677 time_t expiry = 0;
678
679 /* make the changes with the locks held to prevent races */
680 down_write(&key->sem);
681
682 if (timeout > 0) {
683 now = current_kernel_time();
684 expiry = now.tv_sec + timeout;
685 }
686
687 key->expiry = expiry;
688 key_schedule_gc(key->expiry + key_gc_delay);
689
690 up_write(&key->sem);
691}
692EXPORT_SYMBOL_GPL(key_set_timeout);
693
694/*
695 * Unlock a key type locked by key_type_lookup().
696 */
697void key_type_put(struct key_type *ktype)
698{
699 up_read(&key_types_sem);
700}
701
702/*
703 * Attempt to update an existing key.
704 *
705 * The key is given to us with an incremented refcount that we need to discard
706 * if we get an error.
707 */
708static inline key_ref_t __key_update(key_ref_t key_ref,
709 const void *payload, size_t plen)
710{
711 struct key *key = key_ref_to_ptr(key_ref);
712 int ret;
713
714 /* need write permission on the key to update it */
715 ret = key_permission(key_ref, KEY_WRITE);
716 if (ret < 0)
717 goto error;
718
719 ret = -EEXIST;
720 if (!key->type->update)
721 goto error;
722
723 down_write(&key->sem);
724
725 ret = key->type->update(key, payload, plen);
726 if (ret == 0)
727 /* updating a negative key instantiates it */
728 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
729
730 up_write(&key->sem);
731
732 if (ret < 0)
733 goto error;
734out:
735 return key_ref;
736
737error:
738 key_put(key);
739 key_ref = ERR_PTR(ret);
740 goto out;
741}
742
743/**
744 * key_create_or_update - Update or create and instantiate a key.
745 * @keyring_ref: A pointer to the destination keyring with possession flag.
746 * @type: The type of key.
747 * @description: The searchable description for the key.
748 * @payload: The data to use to instantiate or update the key.
749 * @plen: The length of @payload.
750 * @perm: The permissions mask for a new key.
751 * @flags: The quota flags for a new key.
752 *
753 * Search the destination keyring for a key of the same description and if one
754 * is found, update it, otherwise create and instantiate a new one and create a
755 * link to it from that keyring.
756 *
757 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
758 * concocted.
759 *
760 * Returns a pointer to the new key if successful, -ENODEV if the key type
761 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
762 * caller isn't permitted to modify the keyring or the LSM did not permit
763 * creation of the key.
764 *
765 * On success, the possession flag from the keyring ref will be tacked on to
766 * the key ref before it is returned.
767 */
768key_ref_t key_create_or_update(key_ref_t keyring_ref,
769 const char *type,
770 const char *description,
771 const void *payload,
772 size_t plen,
773 key_perm_t perm,
774 unsigned long flags)
775{
776 unsigned long prealloc;
777 const struct cred *cred = current_cred();
778 struct key_type *ktype;
779 struct key *keyring, *key = NULL;
780 key_ref_t key_ref;
781 int ret;
782
783 /* look up the key type to see if it's one of the registered kernel
784 * types */
785 ktype = key_type_lookup(type);
786 if (IS_ERR(ktype)) {
787 key_ref = ERR_PTR(-ENODEV);
788 goto error;
789 }
790
791 key_ref = ERR_PTR(-EINVAL);
792 if (!ktype->match || !ktype->instantiate)
793 goto error_2;
794
795 keyring = key_ref_to_ptr(keyring_ref);
796
797 key_check(keyring);
798
799 key_ref = ERR_PTR(-ENOTDIR);
800 if (keyring->type != &key_type_keyring)
801 goto error_2;
802
803 ret = __key_link_begin(keyring, ktype, description, &prealloc);
804 if (ret < 0)
805 goto error_2;
806
807 /* if we're going to allocate a new key, we're going to have
808 * to modify the keyring */
809 ret = key_permission(keyring_ref, KEY_WRITE);
810 if (ret < 0) {
811 key_ref = ERR_PTR(ret);
812 goto error_3;
813 }
814
815 /* if it's possible to update this type of key, search for an existing
816 * key of the same type and description in the destination keyring and
817 * update that instead if possible
818 */
819 if (ktype->update) {
820 key_ref = __keyring_search_one(keyring_ref, ktype, description,
821 0);
822 if (!IS_ERR(key_ref))
823 goto found_matching_key;
824 }
825
826 /* if the client doesn't provide, decide on the permissions we want */
827 if (perm == KEY_PERM_UNDEF) {
828 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
829 perm |= KEY_USR_VIEW | KEY_USR_SEARCH | KEY_USR_LINK | KEY_USR_SETATTR;
830
831 if (ktype->read)
832 perm |= KEY_POS_READ | KEY_USR_READ;
833
834 if (ktype == &key_type_keyring || ktype->update)
835 perm |= KEY_USR_WRITE;
836 }
837
838 /* allocate a new key */
839 key = key_alloc(ktype, description, cred->fsuid, cred->fsgid, cred,
840 perm, flags);
841 if (IS_ERR(key)) {
842 key_ref = ERR_CAST(key);
843 goto error_3;
844 }
845
846 /* instantiate it and link it into the target keyring */
847 ret = __key_instantiate_and_link(key, payload, plen, keyring, NULL,
848 &prealloc);
849 if (ret < 0) {
850 key_put(key);
851 key_ref = ERR_PTR(ret);
852 goto error_3;
853 }
854
855 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
856
857 error_3:
858 __key_link_end(keyring, ktype, prealloc);
859 error_2:
860 key_type_put(ktype);
861 error:
862 return key_ref;
863
864 found_matching_key:
865 /* we found a matching key, so we're going to try to update it
866 * - we can drop the locks first as we have the key pinned
867 */
868 __key_link_end(keyring, ktype, prealloc);
869 key_type_put(ktype);
870
871 key_ref = __key_update(key_ref, payload, plen);
872 goto error;
873}
874EXPORT_SYMBOL(key_create_or_update);
875
876/**
877 * key_update - Update a key's contents.
878 * @key_ref: The pointer (plus possession flag) to the key.
879 * @payload: The data to be used to update the key.
880 * @plen: The length of @payload.
881 *
882 * Attempt to update the contents of a key with the given payload data. The
883 * caller must be granted Write permission on the key. Negative keys can be
884 * instantiated by this method.
885 *
886 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
887 * type does not support updating. The key type may return other errors.
888 */
889int key_update(key_ref_t key_ref, const void *payload, size_t plen)
890{
891 struct key *key = key_ref_to_ptr(key_ref);
892 int ret;
893
894 key_check(key);
895
896 /* the key must be writable */
897 ret = key_permission(key_ref, KEY_WRITE);
898 if (ret < 0)
899 goto error;
900
901 /* attempt to update it if supported */
902 ret = -EOPNOTSUPP;
903 if (key->type->update) {
904 down_write(&key->sem);
905
906 ret = key->type->update(key, payload, plen);
907 if (ret == 0)
908 /* updating a negative key instantiates it */
909 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
910
911 up_write(&key->sem);
912 }
913
914 error:
915 return ret;
916}
917EXPORT_SYMBOL(key_update);
918
919/**
920 * key_revoke - Revoke a key.
921 * @key: The key to be revoked.
922 *
923 * Mark a key as being revoked and ask the type to free up its resources. The
924 * revocation timeout is set and the key and all its links will be
925 * automatically garbage collected after key_gc_delay amount of time if they
926 * are not manually dealt with first.
927 */
928void key_revoke(struct key *key)
929{
930 struct timespec now;
931 time_t time;
932
933 key_check(key);
934
935 /* make sure no one's trying to change or use the key when we mark it
936 * - we tell lockdep that we might nest because we might be revoking an
937 * authorisation key whilst holding the sem on a key we've just
938 * instantiated
939 */
940 down_write_nested(&key->sem, 1);
941 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
942 key->type->revoke)
943 key->type->revoke(key);
944
945 /* set the death time to no more than the expiry time */
946 now = current_kernel_time();
947 time = now.tv_sec;
948 if (key->revoked_at == 0 || key->revoked_at > time) {
949 key->revoked_at = time;
950 key_schedule_gc(key->revoked_at + key_gc_delay);
951 }
952
953 up_write(&key->sem);
954}
955EXPORT_SYMBOL(key_revoke);
956
957/**
958 * key_invalidate - Invalidate a key.
959 * @key: The key to be invalidated.
960 *
961 * Mark a key as being invalidated and have it cleaned up immediately. The key
962 * is ignored by all searches and other operations from this point.
963 */
964void key_invalidate(struct key *key)
965{
966 kenter("%d", key_serial(key));
967
968 key_check(key);
969
970 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
971 down_write_nested(&key->sem, 1);
972 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags))
973 key_schedule_gc_links();
974 up_write(&key->sem);
975 }
976}
977EXPORT_SYMBOL(key_invalidate);
978
979/**
980 * register_key_type - Register a type of key.
981 * @ktype: The new key type.
982 *
983 * Register a new key type.
984 *
985 * Returns 0 on success or -EEXIST if a type of this name already exists.
986 */
987int register_key_type(struct key_type *ktype)
988{
989 struct key_type *p;
990 int ret;
991
992 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
993
994 ret = -EEXIST;
995 down_write(&key_types_sem);
996
997 /* disallow key types with the same name */
998 list_for_each_entry(p, &key_types_list, link) {
999 if (strcmp(p->name, ktype->name) == 0)
1000 goto out;
1001 }
1002
1003 /* store the type */
1004 list_add(&ktype->link, &key_types_list);
1005
1006 pr_notice("Key type %s registered\n", ktype->name);
1007 ret = 0;
1008
1009out:
1010 up_write(&key_types_sem);
1011 return ret;
1012}
1013EXPORT_SYMBOL(register_key_type);
1014
1015/**
1016 * unregister_key_type - Unregister a type of key.
1017 * @ktype: The key type.
1018 *
1019 * Unregister a key type and mark all the extant keys of this type as dead.
1020 * Those keys of this type are then destroyed to get rid of their payloads and
1021 * they and their links will be garbage collected as soon as possible.
1022 */
1023void unregister_key_type(struct key_type *ktype)
1024{
1025 down_write(&key_types_sem);
1026 list_del_init(&ktype->link);
1027 downgrade_write(&key_types_sem);
1028 key_gc_keytype(ktype);
1029 pr_notice("Key type %s unregistered\n", ktype->name);
1030 up_read(&key_types_sem);
1031}
1032EXPORT_SYMBOL(unregister_key_type);
1033
1034/*
1035 * Initialise the key management state.
1036 */
1037void __init key_init(void)
1038{
1039 /* allocate a slab in which we can store keys */
1040 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1041 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1042
1043 /* add the special key types */
1044 list_add_tail(&key_type_keyring.link, &key_types_list);
1045 list_add_tail(&key_type_dead.link, &key_types_list);
1046 list_add_tail(&key_type_user.link, &key_types_list);
1047 list_add_tail(&key_type_logon.link, &key_types_list);
1048
1049 /* record the root user tracking */
1050 rb_link_node(&root_key_user.node,
1051 NULL,
1052 &key_user_tree.rb_node);
1053
1054 rb_insert_color(&root_key_user.node,
1055 &key_user_tree);
1056}