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
19 struct kmem_cache *key_jar;
20 struct rb_root key_serial_tree; /* tree of keys indexed by serial */
21 DEFINE_SPINLOCK(key_serial_lock);
22
23 struct rb_root key_user_tree; /* tree of quota records indexed by UID */
24 DEFINE_SPINLOCK(key_user_lock);
25
26 unsigned int key_quota_root_maxkeys = 1000000; /* root's key count quota */
27 unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
28 unsigned int key_quota_maxkeys = 200; /* general key count quota */
29 unsigned int key_quota_maxbytes = 20000; /* general key space quota */
30
31 static LIST_HEAD(key_types_list);
32 static DECLARE_RWSEM(key_types_sem);
33
34 /* We serialise key instantiation and link */
35 DEFINE_MUTEX(key_construction_mutex);
36
37 #ifdef KEY_DEBUGGING
__key_check(const struct key * key)38 void __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 */
key_user_lookup(kuid_t uid)50 struct key_user *key_user_lookup(kuid_t uid)
51 {
52 struct key_user *candidate = NULL, *user;
53 struct rb_node *parent, **p;
54
55 try_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 */
108 found:
109 refcount_inc(&user->usage);
110 spin_unlock(&key_user_lock);
111 kfree(candidate);
112 out:
113 return user;
114 }
115
116 /*
117 * Dispose of a user structure
118 */
key_user_put(struct key_user * user)119 void 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 */
key_alloc_serial(struct key * key)133 static 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
148 attempt_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 */
173 serial_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 */
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)224 struct 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 if (flags & KEY_ALLOC_SET_KEEP)
306 key->flags |= 1 << KEY_FLAG_KEEP;
307
308 #ifdef KEY_DEBUGGING
309 key->magic = KEY_DEBUG_MAGIC;
310 #endif
311
312 /* let the security module know about the key */
313 ret = security_key_alloc(key, cred, flags);
314 if (ret < 0)
315 goto security_error;
316
317 /* publish the key by giving it a serial number */
318 refcount_inc(&key->domain_tag->usage);
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_invalidate(authkey);
463
464 if (prep->expiry != TIME64_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 = NULL;
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 = TIME64_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_lock(keyring, &key->index_key);
519 if (ret < 0)
520 goto error;
521
522 ret = __key_link_begin(keyring, &key->index_key, &edit);
523 if (ret < 0)
524 goto error_link_end;
525
526 if (keyring->restrict_link && keyring->restrict_link->check) {
527 struct key_restriction *keyres = keyring->restrict_link;
528
529 ret = keyres->check(keyring, key->type, &prep.payload,
530 keyres->key);
531 if (ret < 0)
532 goto error_link_end;
533 }
534 }
535
536 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
537
538 error_link_end:
539 if (keyring)
540 __key_link_end(keyring, &key->index_key, edit);
541
542 error:
543 if (key->type->preparse)
544 key->type->free_preparse(&prep);
545 return ret;
546 }
547
548 EXPORT_SYMBOL(key_instantiate_and_link);
549
550 /**
551 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
552 * @key: The key to instantiate.
553 * @timeout: The timeout on the negative key.
554 * @error: The error to return when the key is hit.
555 * @keyring: Keyring to create a link in on success (or NULL).
556 * @authkey: The authorisation token permitting instantiation.
557 *
558 * Negatively instantiate a key that's in the uninstantiated state and, if
559 * successful, set its timeout and stored error and link it in to the
560 * destination keyring if one is supplied. The key and any links to the key
561 * will be automatically garbage collected after the timeout expires.
562 *
563 * Negative keys are used to rate limit repeated request_key() calls by causing
564 * them to return the stored error code (typically ENOKEY) until the negative
565 * key expires.
566 *
567 * If successful, 0 is returned, the authorisation token is revoked and anyone
568 * waiting for the key is woken up. If the key was already instantiated,
569 * -EBUSY will be returned.
570 */
key_reject_and_link(struct key * key,unsigned timeout,unsigned error,struct key * keyring,struct key * authkey)571 int key_reject_and_link(struct key *key,
572 unsigned timeout,
573 unsigned error,
574 struct key *keyring,
575 struct key *authkey)
576 {
577 struct assoc_array_edit *edit = NULL;
578 int ret, awaken, link_ret = 0;
579
580 key_check(key);
581 key_check(keyring);
582
583 awaken = 0;
584 ret = -EBUSY;
585
586 if (keyring) {
587 if (keyring->restrict_link)
588 return -EPERM;
589
590 link_ret = __key_link_lock(keyring, &key->index_key);
591 if (link_ret == 0) {
592 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
593 if (link_ret < 0)
594 __key_link_end(keyring, &key->index_key, edit);
595 }
596 }
597
598 mutex_lock(&key_construction_mutex);
599
600 /* can't instantiate twice */
601 if (key->state == KEY_IS_UNINSTANTIATED) {
602 /* mark the key as being negatively instantiated */
603 atomic_inc(&key->user->nikeys);
604 mark_key_instantiated(key, -error);
605 key->expiry = ktime_get_real_seconds() + timeout;
606 key_schedule_gc(key->expiry + key_gc_delay);
607
608 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
609 awaken = 1;
610
611 ret = 0;
612
613 /* and link it into the destination keyring */
614 if (keyring && link_ret == 0)
615 __key_link(key, &edit);
616
617 /* disable the authorisation key */
618 if (authkey)
619 key_invalidate(authkey);
620 }
621
622 mutex_unlock(&key_construction_mutex);
623
624 if (keyring && link_ret == 0)
625 __key_link_end(keyring, &key->index_key, edit);
626
627 /* wake up anyone waiting for a key to be constructed */
628 if (awaken)
629 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
630
631 return ret == 0 ? link_ret : ret;
632 }
633 EXPORT_SYMBOL(key_reject_and_link);
634
635 /**
636 * key_put - Discard a reference to a key.
637 * @key: The key to discard a reference from.
638 *
639 * Discard a reference to a key, and when all the references are gone, we
640 * schedule the cleanup task to come and pull it out of the tree in process
641 * context at some later time.
642 */
key_put(struct key * key)643 void key_put(struct key *key)
644 {
645 if (key) {
646 key_check(key);
647
648 if (refcount_dec_and_test(&key->usage))
649 schedule_work(&key_gc_work);
650 }
651 }
652 EXPORT_SYMBOL(key_put);
653
654 /*
655 * Find a key by its serial number.
656 */
key_lookup(key_serial_t id)657 struct key *key_lookup(key_serial_t id)
658 {
659 struct rb_node *n;
660 struct key *key;
661
662 spin_lock(&key_serial_lock);
663
664 /* search the tree for the specified key */
665 n = key_serial_tree.rb_node;
666 while (n) {
667 key = rb_entry(n, struct key, serial_node);
668
669 if (id < key->serial)
670 n = n->rb_left;
671 else if (id > key->serial)
672 n = n->rb_right;
673 else
674 goto found;
675 }
676
677 not_found:
678 key = ERR_PTR(-ENOKEY);
679 goto error;
680
681 found:
682 /* A key is allowed to be looked up only if someone still owns a
683 * reference to it - otherwise it's awaiting the gc.
684 */
685 if (!refcount_inc_not_zero(&key->usage))
686 goto not_found;
687
688 error:
689 spin_unlock(&key_serial_lock);
690 return key;
691 }
692
693 /*
694 * Find and lock the specified key type against removal.
695 *
696 * We return with the sem read-locked if successful. If the type wasn't
697 * available -ENOKEY is returned instead.
698 */
key_type_lookup(const char * type)699 struct key_type *key_type_lookup(const char *type)
700 {
701 struct key_type *ktype;
702
703 down_read(&key_types_sem);
704
705 /* look up the key type to see if it's one of the registered kernel
706 * types */
707 list_for_each_entry(ktype, &key_types_list, link) {
708 if (strcmp(ktype->name, type) == 0)
709 goto found_kernel_type;
710 }
711
712 up_read(&key_types_sem);
713 ktype = ERR_PTR(-ENOKEY);
714
715 found_kernel_type:
716 return ktype;
717 }
718
key_set_timeout(struct key * key,unsigned timeout)719 void key_set_timeout(struct key *key, unsigned timeout)
720 {
721 time64_t expiry = 0;
722
723 /* make the changes with the locks held to prevent races */
724 down_write(&key->sem);
725
726 if (timeout > 0)
727 expiry = ktime_get_real_seconds() + timeout;
728
729 key->expiry = expiry;
730 key_schedule_gc(key->expiry + key_gc_delay);
731
732 up_write(&key->sem);
733 }
734 EXPORT_SYMBOL_GPL(key_set_timeout);
735
736 /*
737 * Unlock a key type locked by key_type_lookup().
738 */
key_type_put(struct key_type * ktype)739 void key_type_put(struct key_type *ktype)
740 {
741 up_read(&key_types_sem);
742 }
743
744 /*
745 * Attempt to update an existing key.
746 *
747 * The key is given to us with an incremented refcount that we need to discard
748 * if we get an error.
749 */
__key_update(key_ref_t key_ref,struct key_preparsed_payload * prep)750 static inline key_ref_t __key_update(key_ref_t key_ref,
751 struct key_preparsed_payload *prep)
752 {
753 struct key *key = key_ref_to_ptr(key_ref);
754 int ret;
755
756 /* need write permission on the key to update it */
757 ret = key_permission(key_ref, KEY_NEED_WRITE);
758 if (ret < 0)
759 goto error;
760
761 ret = -EEXIST;
762 if (!key->type->update)
763 goto error;
764
765 down_write(&key->sem);
766
767 ret = key->type->update(key, prep);
768 if (ret == 0)
769 /* Updating a negative key positively instantiates it */
770 mark_key_instantiated(key, 0);
771
772 up_write(&key->sem);
773
774 if (ret < 0)
775 goto error;
776 out:
777 return key_ref;
778
779 error:
780 key_put(key);
781 key_ref = ERR_PTR(ret);
782 goto out;
783 }
784
785 /**
786 * key_create_or_update - Update or create and instantiate a key.
787 * @keyring_ref: A pointer to the destination keyring with possession flag.
788 * @type: The type of key.
789 * @description: The searchable description for the key.
790 * @payload: The data to use to instantiate or update the key.
791 * @plen: The length of @payload.
792 * @perm: The permissions mask for a new key.
793 * @flags: The quota flags for a new key.
794 *
795 * Search the destination keyring for a key of the same description and if one
796 * is found, update it, otherwise create and instantiate a new one and create a
797 * link to it from that keyring.
798 *
799 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
800 * concocted.
801 *
802 * Returns a pointer to the new key if successful, -ENODEV if the key type
803 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
804 * caller isn't permitted to modify the keyring or the LSM did not permit
805 * creation of the key.
806 *
807 * On success, the possession flag from the keyring ref will be tacked on to
808 * the key ref before it is returned.
809 */
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)810 key_ref_t key_create_or_update(key_ref_t keyring_ref,
811 const char *type,
812 const char *description,
813 const void *payload,
814 size_t plen,
815 key_perm_t perm,
816 unsigned long flags)
817 {
818 struct keyring_index_key index_key = {
819 .description = description,
820 };
821 struct key_preparsed_payload prep;
822 struct assoc_array_edit *edit = NULL;
823 const struct cred *cred = current_cred();
824 struct key *keyring, *key = NULL;
825 key_ref_t key_ref;
826 int ret;
827 struct key_restriction *restrict_link = NULL;
828
829 /* look up the key type to see if it's one of the registered kernel
830 * types */
831 index_key.type = key_type_lookup(type);
832 if (IS_ERR(index_key.type)) {
833 key_ref = ERR_PTR(-ENODEV);
834 goto error;
835 }
836
837 key_ref = ERR_PTR(-EINVAL);
838 if (!index_key.type->instantiate ||
839 (!index_key.description && !index_key.type->preparse))
840 goto error_put_type;
841
842 keyring = key_ref_to_ptr(keyring_ref);
843
844 key_check(keyring);
845
846 if (!(flags & KEY_ALLOC_BYPASS_RESTRICTION))
847 restrict_link = keyring->restrict_link;
848
849 key_ref = ERR_PTR(-ENOTDIR);
850 if (keyring->type != &key_type_keyring)
851 goto error_put_type;
852
853 memset(&prep, 0, sizeof(prep));
854 prep.data = payload;
855 prep.datalen = plen;
856 prep.quotalen = index_key.type->def_datalen;
857 prep.expiry = TIME64_MAX;
858 if (index_key.type->preparse) {
859 ret = index_key.type->preparse(&prep);
860 if (ret < 0) {
861 key_ref = ERR_PTR(ret);
862 goto error_free_prep;
863 }
864 if (!index_key.description)
865 index_key.description = prep.description;
866 key_ref = ERR_PTR(-EINVAL);
867 if (!index_key.description)
868 goto error_free_prep;
869 }
870 index_key.desc_len = strlen(index_key.description);
871 key_set_index_key(&index_key);
872
873 ret = __key_link_lock(keyring, &index_key);
874 if (ret < 0) {
875 key_ref = ERR_PTR(ret);
876 goto error_free_prep;
877 }
878
879 ret = __key_link_begin(keyring, &index_key, &edit);
880 if (ret < 0) {
881 key_ref = ERR_PTR(ret);
882 goto error_link_end;
883 }
884
885 if (restrict_link && restrict_link->check) {
886 ret = restrict_link->check(keyring, index_key.type,
887 &prep.payload, restrict_link->key);
888 if (ret < 0) {
889 key_ref = ERR_PTR(ret);
890 goto error_link_end;
891 }
892 }
893
894 /* if we're going to allocate a new key, we're going to have
895 * to modify the keyring */
896 ret = key_permission(keyring_ref, KEY_NEED_WRITE);
897 if (ret < 0) {
898 key_ref = ERR_PTR(ret);
899 goto error_link_end;
900 }
901
902 /* if it's possible to update this type of key, search for an existing
903 * key of the same type and description in the destination keyring and
904 * update that instead if possible
905 */
906 if (index_key.type->update) {
907 key_ref = find_key_to_update(keyring_ref, &index_key);
908 if (key_ref)
909 goto found_matching_key;
910 }
911
912 /* if the client doesn't provide, decide on the permissions we want */
913 if (perm == KEY_PERM_UNDEF) {
914 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
915 perm |= KEY_USR_VIEW;
916
917 if (index_key.type->read)
918 perm |= KEY_POS_READ;
919
920 if (index_key.type == &key_type_keyring ||
921 index_key.type->update)
922 perm |= KEY_POS_WRITE;
923 }
924
925 /* allocate a new key */
926 key = key_alloc(index_key.type, index_key.description,
927 cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
928 if (IS_ERR(key)) {
929 key_ref = ERR_CAST(key);
930 goto error_link_end;
931 }
932
933 /* instantiate it and link it into the target keyring */
934 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
935 if (ret < 0) {
936 key_put(key);
937 key_ref = ERR_PTR(ret);
938 goto error_link_end;
939 }
940
941 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
942
943 error_link_end:
944 __key_link_end(keyring, &index_key, edit);
945 error_free_prep:
946 if (index_key.type->preparse)
947 index_key.type->free_preparse(&prep);
948 error_put_type:
949 key_type_put(index_key.type);
950 error:
951 return key_ref;
952
953 found_matching_key:
954 /* we found a matching key, so we're going to try to update it
955 * - we can drop the locks first as we have the key pinned
956 */
957 __key_link_end(keyring, &index_key, edit);
958
959 key = key_ref_to_ptr(key_ref);
960 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) {
961 ret = wait_for_key_construction(key, true);
962 if (ret < 0) {
963 key_ref_put(key_ref);
964 key_ref = ERR_PTR(ret);
965 goto error_free_prep;
966 }
967 }
968
969 key_ref = __key_update(key_ref, &prep);
970 goto error_free_prep;
971 }
972 EXPORT_SYMBOL(key_create_or_update);
973
974 /**
975 * key_update - Update a key's contents.
976 * @key_ref: The pointer (plus possession flag) to the key.
977 * @payload: The data to be used to update the key.
978 * @plen: The length of @payload.
979 *
980 * Attempt to update the contents of a key with the given payload data. The
981 * caller must be granted Write permission on the key. Negative keys can be
982 * instantiated by this method.
983 *
984 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
985 * type does not support updating. The key type may return other errors.
986 */
key_update(key_ref_t key_ref,const void * payload,size_t plen)987 int key_update(key_ref_t key_ref, const void *payload, size_t plen)
988 {
989 struct key_preparsed_payload prep;
990 struct key *key = key_ref_to_ptr(key_ref);
991 int ret;
992
993 key_check(key);
994
995 /* the key must be writable */
996 ret = key_permission(key_ref, KEY_NEED_WRITE);
997 if (ret < 0)
998 return ret;
999
1000 /* attempt to update it if supported */
1001 if (!key->type->update)
1002 return -EOPNOTSUPP;
1003
1004 memset(&prep, 0, sizeof(prep));
1005 prep.data = payload;
1006 prep.datalen = plen;
1007 prep.quotalen = key->type->def_datalen;
1008 prep.expiry = TIME64_MAX;
1009 if (key->type->preparse) {
1010 ret = key->type->preparse(&prep);
1011 if (ret < 0)
1012 goto error;
1013 }
1014
1015 down_write(&key->sem);
1016
1017 ret = key->type->update(key, &prep);
1018 if (ret == 0)
1019 /* Updating a negative key positively instantiates it */
1020 mark_key_instantiated(key, 0);
1021
1022 up_write(&key->sem);
1023
1024 error:
1025 if (key->type->preparse)
1026 key->type->free_preparse(&prep);
1027 return ret;
1028 }
1029 EXPORT_SYMBOL(key_update);
1030
1031 /**
1032 * key_revoke - Revoke a key.
1033 * @key: The key to be revoked.
1034 *
1035 * Mark a key as being revoked and ask the type to free up its resources. The
1036 * revocation timeout is set and the key and all its links will be
1037 * automatically garbage collected after key_gc_delay amount of time if they
1038 * are not manually dealt with first.
1039 */
key_revoke(struct key * key)1040 void key_revoke(struct key *key)
1041 {
1042 time64_t time;
1043
1044 key_check(key);
1045
1046 /* make sure no one's trying to change or use the key when we mark it
1047 * - we tell lockdep that we might nest because we might be revoking an
1048 * authorisation key whilst holding the sem on a key we've just
1049 * instantiated
1050 */
1051 down_write_nested(&key->sem, 1);
1052 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags) &&
1053 key->type->revoke)
1054 key->type->revoke(key);
1055
1056 /* set the death time to no more than the expiry time */
1057 time = ktime_get_real_seconds();
1058 if (key->revoked_at == 0 || key->revoked_at > time) {
1059 key->revoked_at = time;
1060 key_schedule_gc(key->revoked_at + key_gc_delay);
1061 }
1062
1063 up_write(&key->sem);
1064 }
1065 EXPORT_SYMBOL(key_revoke);
1066
1067 /**
1068 * key_invalidate - Invalidate a key.
1069 * @key: The key to be invalidated.
1070 *
1071 * Mark a key as being invalidated and have it cleaned up immediately. The key
1072 * is ignored by all searches and other operations from this point.
1073 */
key_invalidate(struct key * key)1074 void key_invalidate(struct key *key)
1075 {
1076 kenter("%d", key_serial(key));
1077
1078 key_check(key);
1079
1080 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1081 down_write_nested(&key->sem, 1);
1082 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags))
1083 key_schedule_gc_links();
1084 up_write(&key->sem);
1085 }
1086 }
1087 EXPORT_SYMBOL(key_invalidate);
1088
1089 /**
1090 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1091 * @key: The key to be instantiated
1092 * @prep: The preparsed data to load.
1093 *
1094 * Instantiate a key from preparsed data. We assume we can just copy the data
1095 * in directly and clear the old pointers.
1096 *
1097 * This can be pointed to directly by the key type instantiate op pointer.
1098 */
generic_key_instantiate(struct key * key,struct key_preparsed_payload * prep)1099 int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1100 {
1101 int ret;
1102
1103 pr_devel("==>%s()\n", __func__);
1104
1105 ret = key_payload_reserve(key, prep->quotalen);
1106 if (ret == 0) {
1107 rcu_assign_keypointer(key, prep->payload.data[0]);
1108 key->payload.data[1] = prep->payload.data[1];
1109 key->payload.data[2] = prep->payload.data[2];
1110 key->payload.data[3] = prep->payload.data[3];
1111 prep->payload.data[0] = NULL;
1112 prep->payload.data[1] = NULL;
1113 prep->payload.data[2] = NULL;
1114 prep->payload.data[3] = NULL;
1115 }
1116 pr_devel("<==%s() = %d\n", __func__, ret);
1117 return ret;
1118 }
1119 EXPORT_SYMBOL(generic_key_instantiate);
1120
1121 /**
1122 * register_key_type - Register a type of key.
1123 * @ktype: The new key type.
1124 *
1125 * Register a new key type.
1126 *
1127 * Returns 0 on success or -EEXIST if a type of this name already exists.
1128 */
register_key_type(struct key_type * ktype)1129 int register_key_type(struct key_type *ktype)
1130 {
1131 struct key_type *p;
1132 int ret;
1133
1134 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1135
1136 ret = -EEXIST;
1137 down_write(&key_types_sem);
1138
1139 /* disallow key types with the same name */
1140 list_for_each_entry(p, &key_types_list, link) {
1141 if (strcmp(p->name, ktype->name) == 0)
1142 goto out;
1143 }
1144
1145 /* store the type */
1146 list_add(&ktype->link, &key_types_list);
1147
1148 pr_notice("Key type %s registered\n", ktype->name);
1149 ret = 0;
1150
1151 out:
1152 up_write(&key_types_sem);
1153 return ret;
1154 }
1155 EXPORT_SYMBOL(register_key_type);
1156
1157 /**
1158 * unregister_key_type - Unregister a type of key.
1159 * @ktype: The key type.
1160 *
1161 * Unregister a key type and mark all the extant keys of this type as dead.
1162 * Those keys of this type are then destroyed to get rid of their payloads and
1163 * they and their links will be garbage collected as soon as possible.
1164 */
unregister_key_type(struct key_type * ktype)1165 void unregister_key_type(struct key_type *ktype)
1166 {
1167 down_write(&key_types_sem);
1168 list_del_init(&ktype->link);
1169 downgrade_write(&key_types_sem);
1170 key_gc_keytype(ktype);
1171 pr_notice("Key type %s unregistered\n", ktype->name);
1172 up_read(&key_types_sem);
1173 }
1174 EXPORT_SYMBOL(unregister_key_type);
1175
1176 /*
1177 * Initialise the key management state.
1178 */
key_init(void)1179 void __init key_init(void)
1180 {
1181 /* allocate a slab in which we can store keys */
1182 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1183 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1184
1185 /* add the special key types */
1186 list_add_tail(&key_type_keyring.link, &key_types_list);
1187 list_add_tail(&key_type_dead.link, &key_types_list);
1188 list_add_tail(&key_type_user.link, &key_types_list);
1189 list_add_tail(&key_type_logon.link, &key_types_list);
1190
1191 /* record the root user tracking */
1192 rb_link_node(&root_key_user.node,
1193 NULL,
1194 &key_user_tree.rb_node);
1195
1196 rb_insert_color(&root_key_user.node,
1197 &key_user_tree);
1198 }
1199