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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 = 1000000; /* root's key count quota */
31unsigned int key_quota_root_maxbytes = 25000000; /* 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 key->index_key.desc_len = desclen;
280 key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
281 if (!key->index_key.description)
282 goto no_memory_3;
283
284 atomic_set(&key->usage, 1);
285 init_rwsem(&key->sem);
286 lockdep_set_class(&key->sem, &type->lock_class);
287 key->index_key.type = type;
288 key->user = user;
289 key->quotalen = quotalen;
290 key->datalen = type->def_datalen;
291 key->uid = uid;
292 key->gid = gid;
293 key->perm = perm;
294
295 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
296 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
297 if (flags & KEY_ALLOC_TRUSTED)
298 key->flags |= 1 << KEY_FLAG_TRUSTED;
299 if (flags & KEY_ALLOC_BUILT_IN)
300 key->flags |= 1 << KEY_FLAG_BUILTIN;
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 if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
436 set_bit(KEY_FLAG_KEEP, &key->flags);
437
438 __key_link(key, _edit);
439 }
440
441 /* disable the authorisation key */
442 if (authkey)
443 key_revoke(authkey);
444
445 if (prep->expiry != TIME_T_MAX) {
446 key->expiry = prep->expiry;
447 key_schedule_gc(prep->expiry + key_gc_delay);
448 }
449 }
450 }
451
452 mutex_unlock(&key_construction_mutex);
453
454 /* wake up anyone waiting for a key to be constructed */
455 if (awaken)
456 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
457
458 return ret;
459}
460
461/**
462 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
463 * @key: The key to instantiate.
464 * @data: The data to use to instantiate the keyring.
465 * @datalen: The length of @data.
466 * @keyring: Keyring to create a link in on success (or NULL).
467 * @authkey: The authorisation token permitting instantiation.
468 *
469 * Instantiate a key that's in the uninstantiated state using the provided data
470 * and, if successful, link it in to the destination keyring if one is
471 * supplied.
472 *
473 * If successful, 0 is returned, the authorisation token is revoked and anyone
474 * waiting for the key is woken up. If the key was already instantiated,
475 * -EBUSY will be returned.
476 */
477int key_instantiate_and_link(struct key *key,
478 const void *data,
479 size_t datalen,
480 struct key *keyring,
481 struct key *authkey)
482{
483 struct key_preparsed_payload prep;
484 struct assoc_array_edit *edit;
485 int ret;
486
487 memset(&prep, 0, sizeof(prep));
488 prep.data = data;
489 prep.datalen = datalen;
490 prep.quotalen = key->type->def_datalen;
491 prep.expiry = TIME_T_MAX;
492 if (key->type->preparse) {
493 ret = key->type->preparse(&prep);
494 if (ret < 0)
495 goto error;
496 }
497
498 if (keyring) {
499 ret = __key_link_begin(keyring, &key->index_key, &edit);
500 if (ret < 0)
501 goto error;
502 }
503
504 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
505
506 if (keyring)
507 __key_link_end(keyring, &key->index_key, edit);
508
509error:
510 if (key->type->preparse)
511 key->type->free_preparse(&prep);
512 return ret;
513}
514
515EXPORT_SYMBOL(key_instantiate_and_link);
516
517/**
518 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
519 * @key: The key to instantiate.
520 * @timeout: The timeout on the negative key.
521 * @error: The error to return when the key is hit.
522 * @keyring: Keyring to create a link in on success (or NULL).
523 * @authkey: The authorisation token permitting instantiation.
524 *
525 * Negatively instantiate a key that's in the uninstantiated state and, if
526 * successful, set its timeout and stored error and link it in to the
527 * destination keyring if one is supplied. The key and any links to the key
528 * will be automatically garbage collected after the timeout expires.
529 *
530 * Negative keys are used to rate limit repeated request_key() calls by causing
531 * them to return the stored error code (typically ENOKEY) until the negative
532 * key expires.
533 *
534 * If successful, 0 is returned, the authorisation token is revoked and anyone
535 * waiting for the key is woken up. If the key was already instantiated,
536 * -EBUSY will be returned.
537 */
538int key_reject_and_link(struct key *key,
539 unsigned timeout,
540 unsigned error,
541 struct key *keyring,
542 struct key *authkey)
543{
544 struct assoc_array_edit *edit;
545 struct timespec now;
546 int ret, awaken, link_ret = 0;
547
548 key_check(key);
549 key_check(keyring);
550
551 awaken = 0;
552 ret = -EBUSY;
553
554 if (keyring)
555 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
556
557 mutex_lock(&key_construction_mutex);
558
559 /* can't instantiate twice */
560 if (!test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
561 /* mark the key as being negatively instantiated */
562 atomic_inc(&key->user->nikeys);
563 key->reject_error = -error;
564 smp_wmb();
565 set_bit(KEY_FLAG_NEGATIVE, &key->flags);
566 set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
567 now = current_kernel_time();
568 key->expiry = now.tv_sec + timeout;
569 key_schedule_gc(key->expiry + key_gc_delay);
570
571 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
572 awaken = 1;
573
574 ret = 0;
575
576 /* and link it into the destination keyring */
577 if (keyring && link_ret == 0)
578 __key_link(key, &edit);
579
580 /* disable the authorisation key */
581 if (authkey)
582 key_revoke(authkey);
583 }
584
585 mutex_unlock(&key_construction_mutex);
586
587 if (keyring)
588 __key_link_end(keyring, &key->index_key, edit);
589
590 /* wake up anyone waiting for a key to be constructed */
591 if (awaken)
592 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
593
594 return ret == 0 ? link_ret : ret;
595}
596EXPORT_SYMBOL(key_reject_and_link);
597
598/**
599 * key_put - Discard a reference to a key.
600 * @key: The key to discard a reference from.
601 *
602 * Discard a reference to a key, and when all the references are gone, we
603 * schedule the cleanup task to come and pull it out of the tree in process
604 * context at some later time.
605 */
606void key_put(struct key *key)
607{
608 if (key) {
609 key_check(key);
610
611 if (atomic_dec_and_test(&key->usage))
612 schedule_work(&key_gc_work);
613 }
614}
615EXPORT_SYMBOL(key_put);
616
617/*
618 * Find a key by its serial number.
619 */
620struct key *key_lookup(key_serial_t id)
621{
622 struct rb_node *n;
623 struct key *key;
624
625 spin_lock(&key_serial_lock);
626
627 /* search the tree for the specified key */
628 n = key_serial_tree.rb_node;
629 while (n) {
630 key = rb_entry(n, struct key, serial_node);
631
632 if (id < key->serial)
633 n = n->rb_left;
634 else if (id > key->serial)
635 n = n->rb_right;
636 else
637 goto found;
638 }
639
640not_found:
641 key = ERR_PTR(-ENOKEY);
642 goto error;
643
644found:
645 /* pretend it doesn't exist if it is awaiting deletion */
646 if (atomic_read(&key->usage) == 0)
647 goto not_found;
648
649 /* this races with key_put(), but that doesn't matter since key_put()
650 * doesn't actually change the key
651 */
652 __key_get(key);
653
654error:
655 spin_unlock(&key_serial_lock);
656 return key;
657}
658
659/*
660 * Find and lock the specified key type against removal.
661 *
662 * We return with the sem read-locked if successful. If the type wasn't
663 * available -ENOKEY is returned instead.
664 */
665struct key_type *key_type_lookup(const char *type)
666{
667 struct key_type *ktype;
668
669 down_read(&key_types_sem);
670
671 /* look up the key type to see if it's one of the registered kernel
672 * types */
673 list_for_each_entry(ktype, &key_types_list, link) {
674 if (strcmp(ktype->name, type) == 0)
675 goto found_kernel_type;
676 }
677
678 up_read(&key_types_sem);
679 ktype = ERR_PTR(-ENOKEY);
680
681found_kernel_type:
682 return ktype;
683}
684
685void key_set_timeout(struct key *key, unsigned timeout)
686{
687 struct timespec now;
688 time_t expiry = 0;
689
690 /* make the changes with the locks held to prevent races */
691 down_write(&key->sem);
692
693 if (timeout > 0) {
694 now = current_kernel_time();
695 expiry = now.tv_sec + timeout;
696 }
697
698 key->expiry = expiry;
699 key_schedule_gc(key->expiry + key_gc_delay);
700
701 up_write(&key->sem);
702}
703EXPORT_SYMBOL_GPL(key_set_timeout);
704
705/*
706 * Unlock a key type locked by key_type_lookup().
707 */
708void key_type_put(struct key_type *ktype)
709{
710 up_read(&key_types_sem);
711}
712
713/*
714 * Attempt to update an existing key.
715 *
716 * The key is given to us with an incremented refcount that we need to discard
717 * if we get an error.
718 */
719static inline key_ref_t __key_update(key_ref_t key_ref,
720 struct key_preparsed_payload *prep)
721{
722 struct key *key = key_ref_to_ptr(key_ref);
723 int ret;
724
725 /* need write permission on the key to update it */
726 ret = key_permission(key_ref, KEY_NEED_WRITE);
727 if (ret < 0)
728 goto error;
729
730 ret = -EEXIST;
731 if (!key->type->update)
732 goto error;
733
734 down_write(&key->sem);
735
736 ret = key->type->update(key, prep);
737 if (ret == 0)
738 /* updating a negative key instantiates it */
739 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
740
741 up_write(&key->sem);
742
743 if (ret < 0)
744 goto error;
745out:
746 return key_ref;
747
748error:
749 key_put(key);
750 key_ref = ERR_PTR(ret);
751 goto out;
752}
753
754/**
755 * key_create_or_update - Update or create and instantiate a key.
756 * @keyring_ref: A pointer to the destination keyring with possession flag.
757 * @type: The type of key.
758 * @description: The searchable description for the key.
759 * @payload: The data to use to instantiate or update the key.
760 * @plen: The length of @payload.
761 * @perm: The permissions mask for a new key.
762 * @flags: The quota flags for a new key.
763 *
764 * Search the destination keyring for a key of the same description and if one
765 * is found, update it, otherwise create and instantiate a new one and create a
766 * link to it from that keyring.
767 *
768 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
769 * concocted.
770 *
771 * Returns a pointer to the new key if successful, -ENODEV if the key type
772 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
773 * caller isn't permitted to modify the keyring or the LSM did not permit
774 * creation of the key.
775 *
776 * On success, the possession flag from the keyring ref will be tacked on to
777 * the key ref before it is returned.
778 */
779key_ref_t key_create_or_update(key_ref_t keyring_ref,
780 const char *type,
781 const char *description,
782 const void *payload,
783 size_t plen,
784 key_perm_t perm,
785 unsigned long flags)
786{
787 struct keyring_index_key index_key = {
788 .description = description,
789 };
790 struct key_preparsed_payload prep;
791 struct assoc_array_edit *edit;
792 const struct cred *cred = current_cred();
793 struct key *keyring, *key = NULL;
794 key_ref_t key_ref;
795 int ret;
796
797 /* look up the key type to see if it's one of the registered kernel
798 * types */
799 index_key.type = key_type_lookup(type);
800 if (IS_ERR(index_key.type)) {
801 key_ref = ERR_PTR(-ENODEV);
802 goto error;
803 }
804
805 key_ref = ERR_PTR(-EINVAL);
806 if (!index_key.type->instantiate ||
807 (!index_key.description && !index_key.type->preparse))
808 goto error_put_type;
809
810 keyring = key_ref_to_ptr(keyring_ref);
811
812 key_check(keyring);
813
814 key_ref = ERR_PTR(-ENOTDIR);
815 if (keyring->type != &key_type_keyring)
816 goto error_put_type;
817
818 memset(&prep, 0, sizeof(prep));
819 prep.data = payload;
820 prep.datalen = plen;
821 prep.quotalen = index_key.type->def_datalen;
822 prep.trusted = flags & KEY_ALLOC_TRUSTED;
823 prep.expiry = TIME_T_MAX;
824 if (index_key.type->preparse) {
825 ret = index_key.type->preparse(&prep);
826 if (ret < 0) {
827 key_ref = ERR_PTR(ret);
828 goto error_free_prep;
829 }
830 if (!index_key.description)
831 index_key.description = prep.description;
832 key_ref = ERR_PTR(-EINVAL);
833 if (!index_key.description)
834 goto error_free_prep;
835 }
836 index_key.desc_len = strlen(index_key.description);
837
838 key_ref = ERR_PTR(-EPERM);
839 if (!prep.trusted && test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags))
840 goto error_free_prep;
841 flags |= prep.trusted ? KEY_ALLOC_TRUSTED : 0;
842
843 ret = __key_link_begin(keyring, &index_key, &edit);
844 if (ret < 0) {
845 key_ref = ERR_PTR(ret);
846 goto error_free_prep;
847 }
848
849 /* if we're going to allocate a new key, we're going to have
850 * to modify the keyring */
851 ret = key_permission(keyring_ref, KEY_NEED_WRITE);
852 if (ret < 0) {
853 key_ref = ERR_PTR(ret);
854 goto error_link_end;
855 }
856
857 /* if it's possible to update this type of key, search for an existing
858 * key of the same type and description in the destination keyring and
859 * update that instead if possible
860 */
861 if (index_key.type->update) {
862 key_ref = find_key_to_update(keyring_ref, &index_key);
863 if (key_ref)
864 goto found_matching_key;
865 }
866
867 /* if the client doesn't provide, decide on the permissions we want */
868 if (perm == KEY_PERM_UNDEF) {
869 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
870 perm |= KEY_USR_VIEW;
871
872 if (index_key.type->read)
873 perm |= KEY_POS_READ;
874
875 if (index_key.type == &key_type_keyring ||
876 index_key.type->update)
877 perm |= KEY_POS_WRITE;
878 }
879
880 /* allocate a new key */
881 key = key_alloc(index_key.type, index_key.description,
882 cred->fsuid, cred->fsgid, cred, perm, flags);
883 if (IS_ERR(key)) {
884 key_ref = ERR_CAST(key);
885 goto error_link_end;
886 }
887
888 /* instantiate it and link it into the target keyring */
889 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
890 if (ret < 0) {
891 key_put(key);
892 key_ref = ERR_PTR(ret);
893 goto error_link_end;
894 }
895
896 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
897
898error_link_end:
899 __key_link_end(keyring, &index_key, edit);
900error_free_prep:
901 if (index_key.type->preparse)
902 index_key.type->free_preparse(&prep);
903error_put_type:
904 key_type_put(index_key.type);
905error:
906 return key_ref;
907
908 found_matching_key:
909 /* we found a matching key, so we're going to try to update it
910 * - we can drop the locks first as we have the key pinned
911 */
912 __key_link_end(keyring, &index_key, edit);
913
914 key_ref = __key_update(key_ref, &prep);
915 goto error_free_prep;
916}
917EXPORT_SYMBOL(key_create_or_update);
918
919/**
920 * key_update - Update a key's contents.
921 * @key_ref: The pointer (plus possession flag) to the key.
922 * @payload: The data to be used to update the key.
923 * @plen: The length of @payload.
924 *
925 * Attempt to update the contents of a key with the given payload data. The
926 * caller must be granted Write permission on the key. Negative keys can be
927 * instantiated by this method.
928 *
929 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
930 * type does not support updating. The key type may return other errors.
931 */
932int key_update(key_ref_t key_ref, const void *payload, size_t plen)
933{
934 struct key_preparsed_payload prep;
935 struct key *key = key_ref_to_ptr(key_ref);
936 int ret;
937
938 key_check(key);
939
940 /* the key must be writable */
941 ret = key_permission(key_ref, KEY_NEED_WRITE);
942 if (ret < 0)
943 goto error;
944
945 /* attempt to update it if supported */
946 ret = -EOPNOTSUPP;
947 if (!key->type->update)
948 goto error;
949
950 memset(&prep, 0, sizeof(prep));
951 prep.data = payload;
952 prep.datalen = plen;
953 prep.quotalen = key->type->def_datalen;
954 prep.expiry = TIME_T_MAX;
955 if (key->type->preparse) {
956 ret = key->type->preparse(&prep);
957 if (ret < 0)
958 goto error;
959 }
960
961 down_write(&key->sem);
962
963 ret = key->type->update(key, &prep);
964 if (ret == 0)
965 /* updating a negative key instantiates it */
966 clear_bit(KEY_FLAG_NEGATIVE, &key->flags);
967
968 up_write(&key->sem);
969
970error:
971 if (key->type->preparse)
972 key->type->free_preparse(&prep);
973 return ret;
974}
975EXPORT_SYMBOL(key_update);
976
977/**
978 * key_revoke - Revoke a key.
979 * @key: The key to be revoked.
980 *
981 * Mark a key as being revoked and ask the type to free up its resources. The
982 * revocation timeout is set and the key and all its links will be
983 * automatically garbage collected after key_gc_delay amount of time if they
984 * are not manually dealt with first.
985 */
986void key_revoke(struct key *key)
987{
988 struct timespec now;
989 time_t time;
990
991 key_check(key);
992
993 /* make sure no one's trying to change or use the key when we mark it
994 * - we tell lockdep that we might nest because we might be revoking an
995 * authorisation key whilst holding the sem on a key we've just
996 * instantiated
997 */
998 down_write_nested(&key->sem, 1);
999 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
1000 key->type->revoke)
1001 key->type->revoke(key);
1002
1003 /* set the death time to no more than the expiry time */
1004 now = current_kernel_time();
1005 time = now.tv_sec;
1006 if (key->revoked_at == 0 || key->revoked_at > time) {
1007 key->revoked_at = time;
1008 key_schedule_gc(key->revoked_at + key_gc_delay);
1009 }
1010
1011 up_write(&key->sem);
1012}
1013EXPORT_SYMBOL(key_revoke);
1014
1015/**
1016 * key_invalidate - Invalidate a key.
1017 * @key: The key to be invalidated.
1018 *
1019 * Mark a key as being invalidated and have it cleaned up immediately. The key
1020 * is ignored by all searches and other operations from this point.
1021 */
1022void key_invalidate(struct key *key)
1023{
1024 kenter("%d", key_serial(key));
1025
1026 key_check(key);
1027
1028 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1029 down_write_nested(&key->sem, 1);
1030 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags))
1031 key_schedule_gc_links();
1032 up_write(&key->sem);
1033 }
1034}
1035EXPORT_SYMBOL(key_invalidate);
1036
1037/**
1038 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1039 * @key: The key to be instantiated
1040 * @prep: The preparsed data to load.
1041 *
1042 * Instantiate a key from preparsed data. We assume we can just copy the data
1043 * in directly and clear the old pointers.
1044 *
1045 * This can be pointed to directly by the key type instantiate op pointer.
1046 */
1047int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1048{
1049 int ret;
1050
1051 pr_devel("==>%s()\n", __func__);
1052
1053 ret = key_payload_reserve(key, prep->quotalen);
1054 if (ret == 0) {
1055 rcu_assign_keypointer(key, prep->payload.data[0]);
1056 key->payload.data[1] = prep->payload.data[1];
1057 key->payload.data[2] = prep->payload.data[2];
1058 key->payload.data[3] = prep->payload.data[3];
1059 prep->payload.data[0] = NULL;
1060 prep->payload.data[1] = NULL;
1061 prep->payload.data[2] = NULL;
1062 prep->payload.data[3] = NULL;
1063 }
1064 pr_devel("<==%s() = %d\n", __func__, ret);
1065 return ret;
1066}
1067EXPORT_SYMBOL(generic_key_instantiate);
1068
1069/**
1070 * register_key_type - Register a type of key.
1071 * @ktype: The new key type.
1072 *
1073 * Register a new key type.
1074 *
1075 * Returns 0 on success or -EEXIST if a type of this name already exists.
1076 */
1077int register_key_type(struct key_type *ktype)
1078{
1079 struct key_type *p;
1080 int ret;
1081
1082 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1083
1084 ret = -EEXIST;
1085 down_write(&key_types_sem);
1086
1087 /* disallow key types with the same name */
1088 list_for_each_entry(p, &key_types_list, link) {
1089 if (strcmp(p->name, ktype->name) == 0)
1090 goto out;
1091 }
1092
1093 /* store the type */
1094 list_add(&ktype->link, &key_types_list);
1095
1096 pr_notice("Key type %s registered\n", ktype->name);
1097 ret = 0;
1098
1099out:
1100 up_write(&key_types_sem);
1101 return ret;
1102}
1103EXPORT_SYMBOL(register_key_type);
1104
1105/**
1106 * unregister_key_type - Unregister a type of key.
1107 * @ktype: The key type.
1108 *
1109 * Unregister a key type and mark all the extant keys of this type as dead.
1110 * Those keys of this type are then destroyed to get rid of their payloads and
1111 * they and their links will be garbage collected as soon as possible.
1112 */
1113void unregister_key_type(struct key_type *ktype)
1114{
1115 down_write(&key_types_sem);
1116 list_del_init(&ktype->link);
1117 downgrade_write(&key_types_sem);
1118 key_gc_keytype(ktype);
1119 pr_notice("Key type %s unregistered\n", ktype->name);
1120 up_read(&key_types_sem);
1121}
1122EXPORT_SYMBOL(unregister_key_type);
1123
1124/*
1125 * Initialise the key management state.
1126 */
1127void __init key_init(void)
1128{
1129 /* allocate a slab in which we can store keys */
1130 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1131 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1132
1133 /* add the special key types */
1134 list_add_tail(&key_type_keyring.link, &key_types_list);
1135 list_add_tail(&key_type_dead.link, &key_types_list);
1136 list_add_tail(&key_type_user.link, &key_types_list);
1137 list_add_tail(&key_type_logon.link, &key_types_list);
1138
1139 /* record the root user tracking */
1140 rb_link_node(&root_key_user.node,
1141 NULL,
1142 &key_user_tree.rb_node);
1143
1144 rb_insert_color(&root_key_user.node,
1145 &key_user_tree);
1146}
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}