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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 <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}
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}