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