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