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
23 struct kmem_cache *key_jar;
24 struct rb_root key_serial_tree; /* tree of keys indexed by serial */
25 DEFINE_SPINLOCK(key_serial_lock);
26
27 struct rb_root key_user_tree; /* tree of quota records indexed by UID */
28 DEFINE_SPINLOCK(key_user_lock);
29
30 unsigned int key_quota_root_maxkeys = 1000000; /* root's key count quota */
31 unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
32 unsigned int key_quota_maxkeys = 200; /* general key count quota */
33 unsigned int key_quota_maxbytes = 20000; /* general key space quota */
34
35 static LIST_HEAD(key_types_list);
36 static DECLARE_RWSEM(key_types_sem);
37
38 /* We serialise key instantiation and link */
39 DEFINE_MUTEX(key_construction_mutex);
40
41 #ifdef KEY_DEBUGGING
__key_check(const struct key * key)42 void __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 */
key_user_lookup(kuid_t uid)54 struct key_user *key_user_lookup(kuid_t uid)
55 {
56 struct key_user *candidate = NULL, *user;
57 struct rb_node *parent, **p;
58
59 try_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 */
112 found:
113 refcount_inc(&user->usage);
114 spin_unlock(&key_user_lock);
115 kfree(candidate);
116 out:
117 return user;
118 }
119
120 /*
121 * Dispose of a user structure
122 */
key_user_put(struct key_user * user)123 void 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 */
key_alloc_serial(struct key * key)137 static 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
152 attempt_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 */
177 serial_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 */
key_alloc(struct key_type * type,const char * desc,kuid_t uid,kgid_t gid,const struct cred * cred,key_perm_t perm,unsigned long flags,struct key_restriction * restrict_link)228 struct 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 key->last_used_at = ktime_get_real_seconds();
301
302 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
303 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
304 if (flags & KEY_ALLOC_BUILT_IN)
305 key->flags |= 1 << KEY_FLAG_BUILTIN;
306 if (flags & KEY_ALLOC_UID_KEYRING)
307 key->flags |= 1 << KEY_FLAG_UID_KEYRING;
308
309 #ifdef KEY_DEBUGGING
310 key->magic = KEY_DEBUG_MAGIC;
311 #endif
312
313 /* let the security module know about the key */
314 ret = security_key_alloc(key, cred, flags);
315 if (ret < 0)
316 goto security_error;
317
318 /* publish the key by giving it a serial number */
319 atomic_inc(&user->nkeys);
320 key_alloc_serial(key);
321
322 error:
323 return key;
324
325 security_error:
326 kfree(key->description);
327 kmem_cache_free(key_jar, key);
328 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
329 spin_lock(&user->lock);
330 user->qnkeys--;
331 user->qnbytes -= quotalen;
332 spin_unlock(&user->lock);
333 }
334 key_user_put(user);
335 key = ERR_PTR(ret);
336 goto error;
337
338 no_memory_3:
339 kmem_cache_free(key_jar, key);
340 no_memory_2:
341 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
342 spin_lock(&user->lock);
343 user->qnkeys--;
344 user->qnbytes -= quotalen;
345 spin_unlock(&user->lock);
346 }
347 key_user_put(user);
348 no_memory_1:
349 key = ERR_PTR(-ENOMEM);
350 goto error;
351
352 no_quota:
353 spin_unlock(&user->lock);
354 key_user_put(user);
355 key = ERR_PTR(-EDQUOT);
356 goto error;
357 }
358 EXPORT_SYMBOL(key_alloc);
359
360 /**
361 * key_payload_reserve - Adjust data quota reservation for the key's payload
362 * @key: The key to make the reservation for.
363 * @datalen: The amount of data payload the caller now wants.
364 *
365 * Adjust the amount of the owning user's key data quota that a key reserves.
366 * If the amount is increased, then -EDQUOT may be returned if there isn't
367 * enough free quota available.
368 *
369 * If successful, 0 is returned.
370 */
key_payload_reserve(struct key * key,size_t datalen)371 int key_payload_reserve(struct key *key, size_t datalen)
372 {
373 int delta = (int)datalen - key->datalen;
374 int ret = 0;
375
376 key_check(key);
377
378 /* contemplate the quota adjustment */
379 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
380 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
381 key_quota_root_maxbytes : key_quota_maxbytes;
382
383 spin_lock(&key->user->lock);
384
385 if (delta > 0 &&
386 (key->user->qnbytes + delta >= maxbytes ||
387 key->user->qnbytes + delta < key->user->qnbytes)) {
388 ret = -EDQUOT;
389 }
390 else {
391 key->user->qnbytes += delta;
392 key->quotalen += delta;
393 }
394 spin_unlock(&key->user->lock);
395 }
396
397 /* change the recorded data length if that didn't generate an error */
398 if (ret == 0)
399 key->datalen = datalen;
400
401 return ret;
402 }
403 EXPORT_SYMBOL(key_payload_reserve);
404
405 /*
406 * Change the key state to being instantiated.
407 */
mark_key_instantiated(struct key * key,int reject_error)408 static void mark_key_instantiated(struct key *key, int reject_error)
409 {
410 /* Commit the payload before setting the state; barrier versus
411 * key_read_state().
412 */
413 smp_store_release(&key->state,
414 (reject_error < 0) ? reject_error : KEY_IS_POSITIVE);
415 }
416
417 /*
418 * Instantiate a key and link it into the target keyring atomically. Must be
419 * called with the target keyring's semaphore writelocked. The target key's
420 * semaphore need not be locked as instantiation is serialised by
421 * key_construction_mutex.
422 */
__key_instantiate_and_link(struct key * key,struct key_preparsed_payload * prep,struct key * keyring,struct key * authkey,struct assoc_array_edit ** _edit)423 static int __key_instantiate_and_link(struct key *key,
424 struct key_preparsed_payload *prep,
425 struct key *keyring,
426 struct key *authkey,
427 struct assoc_array_edit **_edit)
428 {
429 int ret, awaken;
430
431 key_check(key);
432 key_check(keyring);
433
434 awaken = 0;
435 ret = -EBUSY;
436
437 mutex_lock(&key_construction_mutex);
438
439 /* can't instantiate twice */
440 if (key->state == KEY_IS_UNINSTANTIATED) {
441 /* instantiate the key */
442 ret = key->type->instantiate(key, prep);
443
444 if (ret == 0) {
445 /* mark the key as being instantiated */
446 atomic_inc(&key->user->nikeys);
447 mark_key_instantiated(key, 0);
448
449 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
450 awaken = 1;
451
452 /* and link it into the destination keyring */
453 if (keyring) {
454 if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
455 set_bit(KEY_FLAG_KEEP, &key->flags);
456
457 __key_link(key, _edit);
458 }
459
460 /* disable the authorisation key */
461 if (authkey)
462 key_revoke(authkey);
463
464 if (prep->expiry != TIME_T_MAX) {
465 key->expiry = prep->expiry;
466 key_schedule_gc(prep->expiry + key_gc_delay);
467 }
468 }
469 }
470
471 mutex_unlock(&key_construction_mutex);
472
473 /* wake up anyone waiting for a key to be constructed */
474 if (awaken)
475 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
476
477 return ret;
478 }
479
480 /**
481 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
482 * @key: The key to instantiate.
483 * @data: The data to use to instantiate the keyring.
484 * @datalen: The length of @data.
485 * @keyring: Keyring to create a link in on success (or NULL).
486 * @authkey: The authorisation token permitting instantiation.
487 *
488 * Instantiate a key that's in the uninstantiated state using the provided data
489 * and, if successful, link it in to the destination keyring if one is
490 * supplied.
491 *
492 * If successful, 0 is returned, the authorisation token is revoked and anyone
493 * waiting for the key is woken up. If the key was already instantiated,
494 * -EBUSY will be returned.
495 */
key_instantiate_and_link(struct key * key,const void * data,size_t datalen,struct key * keyring,struct key * authkey)496 int key_instantiate_and_link(struct key *key,
497 const void *data,
498 size_t datalen,
499 struct key *keyring,
500 struct key *authkey)
501 {
502 struct key_preparsed_payload prep;
503 struct assoc_array_edit *edit;
504 int ret;
505
506 memset(&prep, 0, sizeof(prep));
507 prep.data = data;
508 prep.datalen = datalen;
509 prep.quotalen = key->type->def_datalen;
510 prep.expiry = TIME_T_MAX;
511 if (key->type->preparse) {
512 ret = key->type->preparse(&prep);
513 if (ret < 0)
514 goto error;
515 }
516
517 if (keyring) {
518 ret = __key_link_begin(keyring, &key->index_key, &edit);
519 if (ret < 0)
520 goto error;
521
522 if (keyring->restrict_link && keyring->restrict_link->check) {
523 struct key_restriction *keyres = keyring->restrict_link;
524
525 ret = keyres->check(keyring, key->type, &prep.payload,
526 keyres->key);
527 if (ret < 0)
528 goto error_link_end;
529 }
530 }
531
532 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
533
534 error_link_end:
535 if (keyring)
536 __key_link_end(keyring, &key->index_key, edit);
537
538 error:
539 if (key->type->preparse)
540 key->type->free_preparse(&prep);
541 return ret;
542 }
543
544 EXPORT_SYMBOL(key_instantiate_and_link);
545
546 /**
547 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
548 * @key: The key to instantiate.
549 * @timeout: The timeout on the negative key.
550 * @error: The error to return when the key is hit.
551 * @keyring: Keyring to create a link in on success (or NULL).
552 * @authkey: The authorisation token permitting instantiation.
553 *
554 * Negatively instantiate a key that's in the uninstantiated state and, if
555 * successful, set its timeout and stored error and link it in to the
556 * destination keyring if one is supplied. The key and any links to the key
557 * will be automatically garbage collected after the timeout expires.
558 *
559 * Negative keys are used to rate limit repeated request_key() calls by causing
560 * them to return the stored error code (typically ENOKEY) until the negative
561 * key expires.
562 *
563 * If successful, 0 is returned, the authorisation token is revoked and anyone
564 * waiting for the key is woken up. If the key was already instantiated,
565 * -EBUSY will be returned.
566 */
key_reject_and_link(struct key * key,unsigned timeout,unsigned error,struct key * keyring,struct key * authkey)567 int key_reject_and_link(struct key *key,
568 unsigned timeout,
569 unsigned error,
570 struct key *keyring,
571 struct key *authkey)
572 {
573 struct assoc_array_edit *edit;
574 struct timespec now;
575 int ret, awaken, link_ret = 0;
576
577 key_check(key);
578 key_check(keyring);
579
580 awaken = 0;
581 ret = -EBUSY;
582
583 if (keyring) {
584 if (keyring->restrict_link)
585 return -EPERM;
586
587 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
588 }
589
590 mutex_lock(&key_construction_mutex);
591
592 /* can't instantiate twice */
593 if (key->state == KEY_IS_UNINSTANTIATED) {
594 /* mark the key as being negatively instantiated */
595 atomic_inc(&key->user->nikeys);
596 mark_key_instantiated(key, -error);
597 now = current_kernel_time();
598 key->expiry = now.tv_sec + timeout;
599 key_schedule_gc(key->expiry + key_gc_delay);
600
601 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
602 awaken = 1;
603
604 ret = 0;
605
606 /* and link it into the destination keyring */
607 if (keyring && link_ret == 0)
608 __key_link(key, &edit);
609
610 /* disable the authorisation key */
611 if (authkey)
612 key_revoke(authkey);
613 }
614
615 mutex_unlock(&key_construction_mutex);
616
617 if (keyring && link_ret == 0)
618 __key_link_end(keyring, &key->index_key, edit);
619
620 /* wake up anyone waiting for a key to be constructed */
621 if (awaken)
622 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
623
624 return ret == 0 ? link_ret : ret;
625 }
626 EXPORT_SYMBOL(key_reject_and_link);
627
628 /**
629 * key_put - Discard a reference to a key.
630 * @key: The key to discard a reference from.
631 *
632 * Discard a reference to a key, and when all the references are gone, we
633 * schedule the cleanup task to come and pull it out of the tree in process
634 * context at some later time.
635 */
key_put(struct key * key)636 void key_put(struct key *key)
637 {
638 if (key) {
639 key_check(key);
640
641 if (refcount_dec_and_test(&key->usage))
642 schedule_work(&key_gc_work);
643 }
644 }
645 EXPORT_SYMBOL(key_put);
646
647 /*
648 * Find a key by its serial number.
649 */
key_lookup(key_serial_t id)650 struct key *key_lookup(key_serial_t id)
651 {
652 struct rb_node *n;
653 struct key *key;
654
655 spin_lock(&key_serial_lock);
656
657 /* search the tree for the specified key */
658 n = key_serial_tree.rb_node;
659 while (n) {
660 key = rb_entry(n, struct key, serial_node);
661
662 if (id < key->serial)
663 n = n->rb_left;
664 else if (id > key->serial)
665 n = n->rb_right;
666 else
667 goto found;
668 }
669
670 not_found:
671 key = ERR_PTR(-ENOKEY);
672 goto error;
673
674 found:
675 /* A key is allowed to be looked up only if someone still owns a
676 * reference to it - otherwise it's awaiting the gc.
677 */
678 if (!refcount_inc_not_zero(&key->usage))
679 goto not_found;
680
681 error:
682 spin_unlock(&key_serial_lock);
683 return key;
684 }
685
686 /*
687 * Find and lock the specified key type against removal.
688 *
689 * We return with the sem read-locked if successful. If the type wasn't
690 * available -ENOKEY is returned instead.
691 */
key_type_lookup(const char * type)692 struct key_type *key_type_lookup(const char *type)
693 {
694 struct key_type *ktype;
695
696 down_read(&key_types_sem);
697
698 /* look up the key type to see if it's one of the registered kernel
699 * types */
700 list_for_each_entry(ktype, &key_types_list, link) {
701 if (strcmp(ktype->name, type) == 0)
702 goto found_kernel_type;
703 }
704
705 up_read(&key_types_sem);
706 ktype = ERR_PTR(-ENOKEY);
707
708 found_kernel_type:
709 return ktype;
710 }
711
key_set_timeout(struct key * key,unsigned timeout)712 void key_set_timeout(struct key *key, unsigned timeout)
713 {
714 struct timespec now;
715 time_t expiry = 0;
716
717 /* make the changes with the locks held to prevent races */
718 down_write(&key->sem);
719
720 if (timeout > 0) {
721 now = current_kernel_time();
722 expiry = now.tv_sec + timeout;
723 }
724
725 key->expiry = expiry;
726 key_schedule_gc(key->expiry + key_gc_delay);
727
728 up_write(&key->sem);
729 }
730 EXPORT_SYMBOL_GPL(key_set_timeout);
731
732 /*
733 * Unlock a key type locked by key_type_lookup().
734 */
key_type_put(struct key_type * ktype)735 void key_type_put(struct key_type *ktype)
736 {
737 up_read(&key_types_sem);
738 }
739
740 /*
741 * Attempt to update an existing key.
742 *
743 * The key is given to us with an incremented refcount that we need to discard
744 * if we get an error.
745 */
__key_update(key_ref_t key_ref,struct key_preparsed_payload * prep)746 static inline key_ref_t __key_update(key_ref_t key_ref,
747 struct key_preparsed_payload *prep)
748 {
749 struct key *key = key_ref_to_ptr(key_ref);
750 int ret;
751
752 /* need write permission on the key to update it */
753 ret = key_permission(key_ref, KEY_NEED_WRITE);
754 if (ret < 0)
755 goto error;
756
757 ret = -EEXIST;
758 if (!key->type->update)
759 goto error;
760
761 down_write(&key->sem);
762
763 ret = key->type->update(key, prep);
764 if (ret == 0)
765 /* Updating a negative key positively instantiates it */
766 mark_key_instantiated(key, 0);
767
768 up_write(&key->sem);
769
770 if (ret < 0)
771 goto error;
772 out:
773 return key_ref;
774
775 error:
776 key_put(key);
777 key_ref = ERR_PTR(ret);
778 goto out;
779 }
780
781 /**
782 * key_create_or_update - Update or create and instantiate a key.
783 * @keyring_ref: A pointer to the destination keyring with possession flag.
784 * @type: The type of key.
785 * @description: The searchable description for the key.
786 * @payload: The data to use to instantiate or update the key.
787 * @plen: The length of @payload.
788 * @perm: The permissions mask for a new key.
789 * @flags: The quota flags for a new key.
790 *
791 * Search the destination keyring for a key of the same description and if one
792 * is found, update it, otherwise create and instantiate a new one and create a
793 * link to it from that keyring.
794 *
795 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
796 * concocted.
797 *
798 * Returns a pointer to the new key if successful, -ENODEV if the key type
799 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
800 * caller isn't permitted to modify the keyring or the LSM did not permit
801 * creation of the key.
802 *
803 * On success, the possession flag from the keyring ref will be tacked on to
804 * the key ref before it is returned.
805 */
key_create_or_update(key_ref_t keyring_ref,const char * type,const char * description,const void * payload,size_t plen,key_perm_t perm,unsigned long flags)806 key_ref_t key_create_or_update(key_ref_t keyring_ref,
807 const char *type,
808 const char *description,
809 const void *payload,
810 size_t plen,
811 key_perm_t perm,
812 unsigned long flags)
813 {
814 struct keyring_index_key index_key = {
815 .description = description,
816 };
817 struct key_preparsed_payload prep;
818 struct assoc_array_edit *edit;
819 const struct cred *cred = current_cred();
820 struct key *keyring, *key = NULL;
821 key_ref_t key_ref;
822 int ret;
823 struct key_restriction *restrict_link = NULL;
824
825 /* look up the key type to see if it's one of the registered kernel
826 * types */
827 index_key.type = key_type_lookup(type);
828 if (IS_ERR(index_key.type)) {
829 key_ref = ERR_PTR(-ENODEV);
830 goto error;
831 }
832
833 key_ref = ERR_PTR(-EINVAL);
834 if (!index_key.type->instantiate ||
835 (!index_key.description && !index_key.type->preparse))
836 goto error_put_type;
837
838 keyring = key_ref_to_ptr(keyring_ref);
839
840 key_check(keyring);
841
842 key_ref = ERR_PTR(-EPERM);
843 if (!(flags & KEY_ALLOC_BYPASS_RESTRICTION))
844 restrict_link = keyring->restrict_link;
845
846 key_ref = ERR_PTR(-ENOTDIR);
847 if (keyring->type != &key_type_keyring)
848 goto error_put_type;
849
850 memset(&prep, 0, sizeof(prep));
851 prep.data = payload;
852 prep.datalen = plen;
853 prep.quotalen = index_key.type->def_datalen;
854 prep.expiry = TIME_T_MAX;
855 if (index_key.type->preparse) {
856 ret = index_key.type->preparse(&prep);
857 if (ret < 0) {
858 key_ref = ERR_PTR(ret);
859 goto error_free_prep;
860 }
861 if (!index_key.description)
862 index_key.description = prep.description;
863 key_ref = ERR_PTR(-EINVAL);
864 if (!index_key.description)
865 goto error_free_prep;
866 }
867 index_key.desc_len = strlen(index_key.description);
868
869 ret = __key_link_begin(keyring, &index_key, &edit);
870 if (ret < 0) {
871 key_ref = ERR_PTR(ret);
872 goto error_free_prep;
873 }
874
875 if (restrict_link && restrict_link->check) {
876 ret = restrict_link->check(keyring, index_key.type,
877 &prep.payload, restrict_link->key);
878 if (ret < 0) {
879 key_ref = ERR_PTR(ret);
880 goto error_link_end;
881 }
882 }
883
884 /* if we're going to allocate a new key, we're going to have
885 * to modify the keyring */
886 ret = key_permission(keyring_ref, KEY_NEED_WRITE);
887 if (ret < 0) {
888 key_ref = ERR_PTR(ret);
889 goto error_link_end;
890 }
891
892 /* if it's possible to update this type of key, search for an existing
893 * key of the same type and description in the destination keyring and
894 * update that instead if possible
895 */
896 if (index_key.type->update) {
897 key_ref = find_key_to_update(keyring_ref, &index_key);
898 if (key_ref)
899 goto found_matching_key;
900 }
901
902 /* if the client doesn't provide, decide on the permissions we want */
903 if (perm == KEY_PERM_UNDEF) {
904 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
905 perm |= KEY_USR_VIEW;
906
907 if (index_key.type->read)
908 perm |= KEY_POS_READ;
909
910 if (index_key.type == &key_type_keyring ||
911 index_key.type->update)
912 perm |= KEY_POS_WRITE;
913 }
914
915 /* allocate a new key */
916 key = key_alloc(index_key.type, index_key.description,
917 cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
918 if (IS_ERR(key)) {
919 key_ref = ERR_CAST(key);
920 goto error_link_end;
921 }
922
923 /* instantiate it and link it into the target keyring */
924 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
925 if (ret < 0) {
926 key_put(key);
927 key_ref = ERR_PTR(ret);
928 goto error_link_end;
929 }
930
931 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
932
933 error_link_end:
934 __key_link_end(keyring, &index_key, edit);
935 error_free_prep:
936 if (index_key.type->preparse)
937 index_key.type->free_preparse(&prep);
938 error_put_type:
939 key_type_put(index_key.type);
940 error:
941 return key_ref;
942
943 found_matching_key:
944 /* we found a matching key, so we're going to try to update it
945 * - we can drop the locks first as we have the key pinned
946 */
947 __key_link_end(keyring, &index_key, edit);
948
949 key = key_ref_to_ptr(key_ref);
950 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) {
951 ret = wait_for_key_construction(key, true);
952 if (ret < 0) {
953 key_ref_put(key_ref);
954 key_ref = ERR_PTR(ret);
955 goto error_free_prep;
956 }
957 }
958
959 key_ref = __key_update(key_ref, &prep);
960 goto error_free_prep;
961 }
962 EXPORT_SYMBOL(key_create_or_update);
963
964 /**
965 * key_update - Update a key's contents.
966 * @key_ref: The pointer (plus possession flag) to the key.
967 * @payload: The data to be used to update the key.
968 * @plen: The length of @payload.
969 *
970 * Attempt to update the contents of a key with the given payload data. The
971 * caller must be granted Write permission on the key. Negative keys can be
972 * instantiated by this method.
973 *
974 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
975 * type does not support updating. The key type may return other errors.
976 */
key_update(key_ref_t key_ref,const void * payload,size_t plen)977 int key_update(key_ref_t key_ref, const void *payload, size_t plen)
978 {
979 struct key_preparsed_payload prep;
980 struct key *key = key_ref_to_ptr(key_ref);
981 int ret;
982
983 key_check(key);
984
985 /* the key must be writable */
986 ret = key_permission(key_ref, KEY_NEED_WRITE);
987 if (ret < 0)
988 return ret;
989
990 /* attempt to update it if supported */
991 if (!key->type->update)
992 return -EOPNOTSUPP;
993
994 memset(&prep, 0, sizeof(prep));
995 prep.data = payload;
996 prep.datalen = plen;
997 prep.quotalen = key->type->def_datalen;
998 prep.expiry = TIME_T_MAX;
999 if (key->type->preparse) {
1000 ret = key->type->preparse(&prep);
1001 if (ret < 0)
1002 goto error;
1003 }
1004
1005 down_write(&key->sem);
1006
1007 ret = key->type->update(key, &prep);
1008 if (ret == 0)
1009 /* Updating a negative key positively instantiates it */
1010 mark_key_instantiated(key, 0);
1011
1012 up_write(&key->sem);
1013
1014 error:
1015 if (key->type->preparse)
1016 key->type->free_preparse(&prep);
1017 return ret;
1018 }
1019 EXPORT_SYMBOL(key_update);
1020
1021 /**
1022 * key_revoke - Revoke a key.
1023 * @key: The key to be revoked.
1024 *
1025 * Mark a key as being revoked and ask the type to free up its resources. The
1026 * revocation timeout is set and the key and all its links will be
1027 * automatically garbage collected after key_gc_delay amount of time if they
1028 * are not manually dealt with first.
1029 */
key_revoke(struct key * key)1030 void key_revoke(struct key *key)
1031 {
1032 struct timespec now;
1033 time_t time;
1034
1035 key_check(key);
1036
1037 /* make sure no one's trying to change or use the key when we mark it
1038 * - we tell lockdep that we might nest because we might be revoking an
1039 * authorisation key whilst holding the sem on a key we've just
1040 * instantiated
1041 */
1042 down_write_nested(&key->sem, 1);
1043 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
1044 key->type->revoke)
1045 key->type->revoke(key);
1046
1047 /* set the death time to no more than the expiry time */
1048 now = current_kernel_time();
1049 time = now.tv_sec;
1050 if (key->revoked_at == 0 || key->revoked_at > time) {
1051 key->revoked_at = time;
1052 key_schedule_gc(key->revoked_at + key_gc_delay);
1053 }
1054
1055 up_write(&key->sem);
1056 }
1057 EXPORT_SYMBOL(key_revoke);
1058
1059 /**
1060 * key_invalidate - Invalidate a key.
1061 * @key: The key to be invalidated.
1062 *
1063 * Mark a key as being invalidated and have it cleaned up immediately. The key
1064 * is ignored by all searches and other operations from this point.
1065 */
key_invalidate(struct key * key)1066 void key_invalidate(struct key *key)
1067 {
1068 kenter("%d", key_serial(key));
1069
1070 key_check(key);
1071
1072 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1073 down_write_nested(&key->sem, 1);
1074 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags))
1075 key_schedule_gc_links();
1076 up_write(&key->sem);
1077 }
1078 }
1079 EXPORT_SYMBOL(key_invalidate);
1080
1081 /**
1082 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1083 * @key: The key to be instantiated
1084 * @prep: The preparsed data to load.
1085 *
1086 * Instantiate a key from preparsed data. We assume we can just copy the data
1087 * in directly and clear the old pointers.
1088 *
1089 * This can be pointed to directly by the key type instantiate op pointer.
1090 */
generic_key_instantiate(struct key * key,struct key_preparsed_payload * prep)1091 int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1092 {
1093 int ret;
1094
1095 pr_devel("==>%s()\n", __func__);
1096
1097 ret = key_payload_reserve(key, prep->quotalen);
1098 if (ret == 0) {
1099 rcu_assign_keypointer(key, prep->payload.data[0]);
1100 key->payload.data[1] = prep->payload.data[1];
1101 key->payload.data[2] = prep->payload.data[2];
1102 key->payload.data[3] = prep->payload.data[3];
1103 prep->payload.data[0] = NULL;
1104 prep->payload.data[1] = NULL;
1105 prep->payload.data[2] = NULL;
1106 prep->payload.data[3] = NULL;
1107 }
1108 pr_devel("<==%s() = %d\n", __func__, ret);
1109 return ret;
1110 }
1111 EXPORT_SYMBOL(generic_key_instantiate);
1112
1113 /**
1114 * register_key_type - Register a type of key.
1115 * @ktype: The new key type.
1116 *
1117 * Register a new key type.
1118 *
1119 * Returns 0 on success or -EEXIST if a type of this name already exists.
1120 */
register_key_type(struct key_type * ktype)1121 int register_key_type(struct key_type *ktype)
1122 {
1123 struct key_type *p;
1124 int ret;
1125
1126 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1127
1128 ret = -EEXIST;
1129 down_write(&key_types_sem);
1130
1131 /* disallow key types with the same name */
1132 list_for_each_entry(p, &key_types_list, link) {
1133 if (strcmp(p->name, ktype->name) == 0)
1134 goto out;
1135 }
1136
1137 /* store the type */
1138 list_add(&ktype->link, &key_types_list);
1139
1140 pr_notice("Key type %s registered\n", ktype->name);
1141 ret = 0;
1142
1143 out:
1144 up_write(&key_types_sem);
1145 return ret;
1146 }
1147 EXPORT_SYMBOL(register_key_type);
1148
1149 /**
1150 * unregister_key_type - Unregister a type of key.
1151 * @ktype: The key type.
1152 *
1153 * Unregister a key type and mark all the extant keys of this type as dead.
1154 * Those keys of this type are then destroyed to get rid of their payloads and
1155 * they and their links will be garbage collected as soon as possible.
1156 */
unregister_key_type(struct key_type * ktype)1157 void unregister_key_type(struct key_type *ktype)
1158 {
1159 down_write(&key_types_sem);
1160 list_del_init(&ktype->link);
1161 downgrade_write(&key_types_sem);
1162 key_gc_keytype(ktype);
1163 pr_notice("Key type %s unregistered\n", ktype->name);
1164 up_read(&key_types_sem);
1165 }
1166 EXPORT_SYMBOL(unregister_key_type);
1167
1168 /*
1169 * Initialise the key management state.
1170 */
key_init(void)1171 void __init key_init(void)
1172 {
1173 /* allocate a slab in which we can store keys */
1174 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1175 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1176
1177 /* add the special key types */
1178 list_add_tail(&key_type_keyring.link, &key_types_list);
1179 list_add_tail(&key_type_dead.link, &key_types_list);
1180 list_add_tail(&key_type_user.link, &key_types_list);
1181 list_add_tail(&key_type_logon.link, &key_types_list);
1182
1183 /* record the root user tracking */
1184 rb_link_node(&root_key_user.node,
1185 NULL,
1186 &key_user_tree.rb_node);
1187
1188 rb_insert_color(&root_key_user.node,
1189 &key_user_tree);
1190 }
1191