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