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/ima.h>
17 #include <linux/err.h>
18 #include "internal.h"
19
20 struct kmem_cache *key_jar;
21 struct rb_root key_serial_tree; /* tree of keys indexed by serial */
22 DEFINE_SPINLOCK(key_serial_lock);
23
24 struct rb_root key_user_tree; /* tree of quota records indexed by UID */
25 DEFINE_SPINLOCK(key_user_lock);
26
27 unsigned int key_quota_root_maxkeys = 1000000; /* root's key count quota */
28 unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
29 unsigned int key_quota_maxkeys = 200; /* general key count quota */
30 unsigned int key_quota_maxbytes = 20000; /* general key space quota */
31
32 static LIST_HEAD(key_types_list);
33 static DECLARE_RWSEM(key_types_sem);
34
35 /* We serialise key instantiation and link */
36 DEFINE_MUTEX(key_construction_mutex);
37
38 #ifdef KEY_DEBUGGING
__key_check(const struct key * key)39 void __key_check(const struct key *key)
40 {
41 printk("__key_check: key %p {%08x} should be {%08x}\n",
42 key, key->magic, KEY_DEBUG_MAGIC);
43 BUG();
44 }
45 #endif
46
47 /*
48 * Get the key quota record for a user, allocating a new record if one doesn't
49 * already exist.
50 */
key_user_lookup(kuid_t uid)51 struct key_user *key_user_lookup(kuid_t uid)
52 {
53 struct key_user *candidate = NULL, *user;
54 struct rb_node *parent, **p;
55
56 try_again:
57 parent = NULL;
58 p = &key_user_tree.rb_node;
59 spin_lock(&key_user_lock);
60
61 /* search the tree for a user record with a matching UID */
62 while (*p) {
63 parent = *p;
64 user = rb_entry(parent, struct key_user, node);
65
66 if (uid_lt(uid, user->uid))
67 p = &(*p)->rb_left;
68 else if (uid_gt(uid, user->uid))
69 p = &(*p)->rb_right;
70 else
71 goto found;
72 }
73
74 /* if we get here, we failed to find a match in the tree */
75 if (!candidate) {
76 /* allocate a candidate user record if we don't already have
77 * one */
78 spin_unlock(&key_user_lock);
79
80 user = NULL;
81 candidate = kmalloc(sizeof(struct key_user), GFP_KERNEL);
82 if (unlikely(!candidate))
83 goto out;
84
85 /* the allocation may have scheduled, so we need to repeat the
86 * search lest someone else added the record whilst we were
87 * asleep */
88 goto try_again;
89 }
90
91 /* if we get here, then the user record still hadn't appeared on the
92 * second pass - so we use the candidate record */
93 refcount_set(&candidate->usage, 1);
94 atomic_set(&candidate->nkeys, 0);
95 atomic_set(&candidate->nikeys, 0);
96 candidate->uid = uid;
97 candidate->qnkeys = 0;
98 candidate->qnbytes = 0;
99 spin_lock_init(&candidate->lock);
100 mutex_init(&candidate->cons_lock);
101
102 rb_link_node(&candidate->node, parent, p);
103 rb_insert_color(&candidate->node, &key_user_tree);
104 spin_unlock(&key_user_lock);
105 user = candidate;
106 goto out;
107
108 /* okay - we found a user record for this UID */
109 found:
110 refcount_inc(&user->usage);
111 spin_unlock(&key_user_lock);
112 kfree(candidate);
113 out:
114 return user;
115 }
116
117 /*
118 * Dispose of a user structure
119 */
key_user_put(struct key_user * user)120 void key_user_put(struct key_user *user)
121 {
122 if (refcount_dec_and_lock(&user->usage, &key_user_lock)) {
123 rb_erase(&user->node, &key_user_tree);
124 spin_unlock(&key_user_lock);
125
126 kfree(user);
127 }
128 }
129
130 /*
131 * Allocate a serial number for a key. These are assigned randomly to avoid
132 * security issues through covert channel problems.
133 */
key_alloc_serial(struct key * key)134 static inline void key_alloc_serial(struct key *key)
135 {
136 struct rb_node *parent, **p;
137 struct key *xkey;
138
139 /* propose a random serial number and look for a hole for it in the
140 * serial number tree */
141 do {
142 get_random_bytes(&key->serial, sizeof(key->serial));
143
144 key->serial >>= 1; /* negative numbers are not permitted */
145 } while (key->serial < 3);
146
147 spin_lock(&key_serial_lock);
148
149 attempt_insertion:
150 parent = NULL;
151 p = &key_serial_tree.rb_node;
152
153 while (*p) {
154 parent = *p;
155 xkey = rb_entry(parent, struct key, serial_node);
156
157 if (key->serial < xkey->serial)
158 p = &(*p)->rb_left;
159 else if (key->serial > xkey->serial)
160 p = &(*p)->rb_right;
161 else
162 goto serial_exists;
163 }
164
165 /* we've found a suitable hole - arrange for this key to occupy it */
166 rb_link_node(&key->serial_node, parent, p);
167 rb_insert_color(&key->serial_node, &key_serial_tree);
168
169 spin_unlock(&key_serial_lock);
170 return;
171
172 /* we found a key with the proposed serial number - walk the tree from
173 * that point looking for the next unused serial number */
174 serial_exists:
175 for (;;) {
176 key->serial++;
177 if (key->serial < 3) {
178 key->serial = 3;
179 goto attempt_insertion;
180 }
181
182 parent = rb_next(parent);
183 if (!parent)
184 goto attempt_insertion;
185
186 xkey = rb_entry(parent, struct key, serial_node);
187 if (key->serial < xkey->serial)
188 goto attempt_insertion;
189 }
190 }
191
192 /**
193 * key_alloc - Allocate a key of the specified type.
194 * @type: The type of key to allocate.
195 * @desc: The key description to allow the key to be searched out.
196 * @uid: The owner of the new key.
197 * @gid: The group ID for the new key's group permissions.
198 * @cred: The credentials specifying UID namespace.
199 * @perm: The permissions mask of the new key.
200 * @flags: Flags specifying quota properties.
201 * @restrict_link: Optional link restriction for new keyrings.
202 *
203 * Allocate a key of the specified type with the attributes given. The key is
204 * returned in an uninstantiated state and the caller needs to instantiate the
205 * key before returning.
206 *
207 * The restrict_link structure (if not NULL) will be freed when the
208 * keyring is destroyed, so it must be dynamically allocated.
209 *
210 * The user's key count quota is updated to reflect the creation of the key and
211 * the user's key data quota has the default for the key type reserved. The
212 * instantiation function should amend this as necessary. If insufficient
213 * quota is available, -EDQUOT will be returned.
214 *
215 * The LSM security modules can prevent a key being created, in which case
216 * -EACCES will be returned.
217 *
218 * Returns a pointer to the new key if successful and an error code otherwise.
219 *
220 * Note that the caller needs to ensure the key type isn't uninstantiated.
221 * Internally this can be done by locking key_types_sem. Externally, this can
222 * be done by either never unregistering the key type, or making sure
223 * key_alloc() calls don't race with module unloading.
224 */
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)225 struct key *key_alloc(struct key_type *type, const char *desc,
226 kuid_t uid, kgid_t gid, const struct cred *cred,
227 key_perm_t perm, unsigned long flags,
228 struct key_restriction *restrict_link)
229 {
230 struct key_user *user = NULL;
231 struct key *key;
232 size_t desclen, quotalen;
233 int ret;
234
235 key = ERR_PTR(-EINVAL);
236 if (!desc || !*desc)
237 goto error;
238
239 if (type->vet_description) {
240 ret = type->vet_description(desc);
241 if (ret < 0) {
242 key = ERR_PTR(ret);
243 goto error;
244 }
245 }
246
247 desclen = strlen(desc);
248 quotalen = desclen + 1 + type->def_datalen;
249
250 /* get hold of the key tracking for this user */
251 user = key_user_lookup(uid);
252 if (!user)
253 goto no_memory_1;
254
255 /* check that the user's quota permits allocation of another key and
256 * its description */
257 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
258 unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
259 key_quota_root_maxkeys : key_quota_maxkeys;
260 unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
261 key_quota_root_maxbytes : key_quota_maxbytes;
262
263 spin_lock(&user->lock);
264 if (!(flags & KEY_ALLOC_QUOTA_OVERRUN)) {
265 if (user->qnkeys + 1 > maxkeys ||
266 user->qnbytes + quotalen > maxbytes ||
267 user->qnbytes + quotalen < user->qnbytes)
268 goto no_quota;
269 }
270
271 user->qnkeys++;
272 user->qnbytes += quotalen;
273 spin_unlock(&user->lock);
274 }
275
276 /* allocate and initialise the key and its description */
277 key = kmem_cache_zalloc(key_jar, GFP_KERNEL);
278 if (!key)
279 goto no_memory_2;
280
281 key->index_key.desc_len = desclen;
282 key->index_key.description = kmemdup(desc, desclen + 1, GFP_KERNEL);
283 if (!key->index_key.description)
284 goto no_memory_3;
285 key->index_key.type = type;
286 key_set_index_key(&key->index_key);
287
288 refcount_set(&key->usage, 1);
289 init_rwsem(&key->sem);
290 lockdep_set_class(&key->sem, &type->lock_class);
291 key->user = user;
292 key->quotalen = quotalen;
293 key->datalen = type->def_datalen;
294 key->uid = uid;
295 key->gid = gid;
296 key->perm = perm;
297 key->expiry = TIME64_MAX;
298 key->restrict_link = restrict_link;
299 key->last_used_at = ktime_get_real_seconds();
300
301 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
302 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
303 if (flags & KEY_ALLOC_BUILT_IN)
304 key->flags |= 1 << KEY_FLAG_BUILTIN;
305 if (flags & KEY_ALLOC_UID_KEYRING)
306 key->flags |= 1 << KEY_FLAG_UID_KEYRING;
307 if (flags & KEY_ALLOC_SET_KEEP)
308 key->flags |= 1 << KEY_FLAG_KEEP;
309
310 #ifdef KEY_DEBUGGING
311 key->magic = KEY_DEBUG_MAGIC;
312 #endif
313
314 /* let the security module know about the key */
315 ret = security_key_alloc(key, cred, flags);
316 if (ret < 0)
317 goto security_error;
318
319 /* publish the key by giving it a serial number */
320 refcount_inc(&key->domain_tag->usage);
321 atomic_inc(&user->nkeys);
322 key_alloc_serial(key);
323
324 error:
325 return key;
326
327 security_error:
328 kfree(key->description);
329 kmem_cache_free(key_jar, key);
330 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
331 spin_lock(&user->lock);
332 user->qnkeys--;
333 user->qnbytes -= quotalen;
334 spin_unlock(&user->lock);
335 }
336 key_user_put(user);
337 key = ERR_PTR(ret);
338 goto error;
339
340 no_memory_3:
341 kmem_cache_free(key_jar, key);
342 no_memory_2:
343 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
344 spin_lock(&user->lock);
345 user->qnkeys--;
346 user->qnbytes -= quotalen;
347 spin_unlock(&user->lock);
348 }
349 key_user_put(user);
350 no_memory_1:
351 key = ERR_PTR(-ENOMEM);
352 goto error;
353
354 no_quota:
355 spin_unlock(&user->lock);
356 key_user_put(user);
357 key = ERR_PTR(-EDQUOT);
358 goto error;
359 }
360 EXPORT_SYMBOL(key_alloc);
361
362 /**
363 * key_payload_reserve - Adjust data quota reservation for the key's payload
364 * @key: The key to make the reservation for.
365 * @datalen: The amount of data payload the caller now wants.
366 *
367 * Adjust the amount of the owning user's key data quota that a key reserves.
368 * If the amount is increased, then -EDQUOT may be returned if there isn't
369 * enough free quota available.
370 *
371 * If successful, 0 is returned.
372 */
key_payload_reserve(struct key * key,size_t datalen)373 int key_payload_reserve(struct key *key, size_t datalen)
374 {
375 int delta = (int)datalen - key->datalen;
376 int ret = 0;
377
378 key_check(key);
379
380 /* contemplate the quota adjustment */
381 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
382 unsigned maxbytes = uid_eq(key->user->uid, GLOBAL_ROOT_UID) ?
383 key_quota_root_maxbytes : key_quota_maxbytes;
384
385 spin_lock(&key->user->lock);
386
387 if (delta > 0 &&
388 (key->user->qnbytes + delta > maxbytes ||
389 key->user->qnbytes + delta < key->user->qnbytes)) {
390 ret = -EDQUOT;
391 }
392 else {
393 key->user->qnbytes += delta;
394 key->quotalen += delta;
395 }
396 spin_unlock(&key->user->lock);
397 }
398
399 /* change the recorded data length if that didn't generate an error */
400 if (ret == 0)
401 key->datalen = datalen;
402
403 return ret;
404 }
405 EXPORT_SYMBOL(key_payload_reserve);
406
407 /*
408 * Change the key state to being instantiated.
409 */
mark_key_instantiated(struct key * key,int reject_error)410 static void mark_key_instantiated(struct key *key, int reject_error)
411 {
412 /* Commit the payload before setting the state; barrier versus
413 * key_read_state().
414 */
415 smp_store_release(&key->state,
416 (reject_error < 0) ? reject_error : KEY_IS_POSITIVE);
417 }
418
419 /*
420 * Instantiate a key and link it into the target keyring atomically. Must be
421 * called with the target keyring's semaphore writelocked. The target key's
422 * semaphore need not be locked as instantiation is serialised by
423 * key_construction_mutex.
424 */
__key_instantiate_and_link(struct key * key,struct key_preparsed_payload * prep,struct key * keyring,struct key * authkey,struct assoc_array_edit ** _edit)425 static int __key_instantiate_and_link(struct key *key,
426 struct key_preparsed_payload *prep,
427 struct key *keyring,
428 struct key *authkey,
429 struct assoc_array_edit **_edit)
430 {
431 int ret, awaken;
432
433 key_check(key);
434 key_check(keyring);
435
436 awaken = 0;
437 ret = -EBUSY;
438
439 mutex_lock(&key_construction_mutex);
440
441 /* can't instantiate twice */
442 if (key->state == KEY_IS_UNINSTANTIATED) {
443 /* instantiate the key */
444 ret = key->type->instantiate(key, prep);
445
446 if (ret == 0) {
447 /* mark the key as being instantiated */
448 atomic_inc(&key->user->nikeys);
449 mark_key_instantiated(key, 0);
450 notify_key(key, NOTIFY_KEY_INSTANTIATED, 0);
451
452 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
453 awaken = 1;
454
455 /* and link it into the destination keyring */
456 if (keyring) {
457 if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
458 set_bit(KEY_FLAG_KEEP, &key->flags);
459
460 __key_link(keyring, key, _edit);
461 }
462
463 /* disable the authorisation key */
464 if (authkey)
465 key_invalidate(authkey);
466
467 key_set_expiry(key, prep->expiry);
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.orig_description = key->description;
508 prep.data = data;
509 prep.datalen = datalen;
510 prep.quotalen = key->type->def_datalen;
511 prep.expiry = TIME64_MAX;
512 if (key->type->preparse) {
513 ret = key->type->preparse(&prep);
514 if (ret < 0)
515 goto error;
516 }
517
518 if (keyring) {
519 ret = __key_link_lock(keyring, &key->index_key);
520 if (ret < 0)
521 goto error;
522
523 ret = __key_link_begin(keyring, &key->index_key, &edit);
524 if (ret < 0)
525 goto error_link_end;
526
527 if (keyring->restrict_link && keyring->restrict_link->check) {
528 struct key_restriction *keyres = keyring->restrict_link;
529
530 ret = keyres->check(keyring, key->type, &prep.payload,
531 keyres->key);
532 if (ret < 0)
533 goto error_link_end;
534 }
535 }
536
537 ret = __key_instantiate_and_link(key, &prep, keyring, authkey, &edit);
538
539 error_link_end:
540 if (keyring)
541 __key_link_end(keyring, &key->index_key, edit);
542
543 error:
544 if (key->type->preparse)
545 key->type->free_preparse(&prep);
546 return ret;
547 }
548
549 EXPORT_SYMBOL(key_instantiate_and_link);
550
551 /**
552 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
553 * @key: The key to instantiate.
554 * @timeout: The timeout on the negative key.
555 * @error: The error to return when the key is hit.
556 * @keyring: Keyring to create a link in on success (or NULL).
557 * @authkey: The authorisation token permitting instantiation.
558 *
559 * Negatively instantiate a key that's in the uninstantiated state and, if
560 * successful, set its timeout and stored error and link it in to the
561 * destination keyring if one is supplied. The key and any links to the key
562 * will be automatically garbage collected after the timeout expires.
563 *
564 * Negative keys are used to rate limit repeated request_key() calls by causing
565 * them to return the stored error code (typically ENOKEY) until the negative
566 * key expires.
567 *
568 * If successful, 0 is returned, the authorisation token is revoked and anyone
569 * waiting for the key is woken up. If the key was already instantiated,
570 * -EBUSY will be returned.
571 */
key_reject_and_link(struct key * key,unsigned timeout,unsigned error,struct key * keyring,struct key * authkey)572 int key_reject_and_link(struct key *key,
573 unsigned timeout,
574 unsigned error,
575 struct key *keyring,
576 struct key *authkey)
577 {
578 struct assoc_array_edit *edit = NULL;
579 int ret, awaken, link_ret = 0;
580
581 key_check(key);
582 key_check(keyring);
583
584 awaken = 0;
585 ret = -EBUSY;
586
587 if (keyring) {
588 if (keyring->restrict_link)
589 return -EPERM;
590
591 link_ret = __key_link_lock(keyring, &key->index_key);
592 if (link_ret == 0) {
593 link_ret = __key_link_begin(keyring, &key->index_key, &edit);
594 if (link_ret < 0)
595 __key_link_end(keyring, &key->index_key, edit);
596 }
597 }
598
599 mutex_lock(&key_construction_mutex);
600
601 /* can't instantiate twice */
602 if (key->state == KEY_IS_UNINSTANTIATED) {
603 /* mark the key as being negatively instantiated */
604 atomic_inc(&key->user->nikeys);
605 mark_key_instantiated(key, -error);
606 notify_key(key, NOTIFY_KEY_INSTANTIATED, -error);
607 key_set_expiry(key, ktime_get_real_seconds() + timeout);
608
609 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags))
610 awaken = 1;
611
612 ret = 0;
613
614 /* and link it into the destination keyring */
615 if (keyring && link_ret == 0)
616 __key_link(keyring, key, &edit);
617
618 /* disable the authorisation key */
619 if (authkey)
620 key_invalidate(authkey);
621 }
622
623 mutex_unlock(&key_construction_mutex);
624
625 if (keyring && link_ret == 0)
626 __key_link_end(keyring, &key->index_key, edit);
627
628 /* wake up anyone waiting for a key to be constructed */
629 if (awaken)
630 wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
631
632 return ret == 0 ? link_ret : ret;
633 }
634 EXPORT_SYMBOL(key_reject_and_link);
635
636 /**
637 * key_put - Discard a reference to a key.
638 * @key: The key to discard a reference from.
639 *
640 * Discard a reference to a key, and when all the references are gone, we
641 * schedule the cleanup task to come and pull it out of the tree in process
642 * context at some later time.
643 */
key_put(struct key * key)644 void key_put(struct key *key)
645 {
646 if (key) {
647 key_check(key);
648
649 if (refcount_dec_and_test(&key->usage))
650 schedule_work(&key_gc_work);
651 }
652 }
653 EXPORT_SYMBOL(key_put);
654
655 /*
656 * Find a key by its serial number.
657 */
key_lookup(key_serial_t id)658 struct key *key_lookup(key_serial_t id)
659 {
660 struct rb_node *n;
661 struct key *key;
662
663 spin_lock(&key_serial_lock);
664
665 /* search the tree for the specified key */
666 n = key_serial_tree.rb_node;
667 while (n) {
668 key = rb_entry(n, struct key, serial_node);
669
670 if (id < key->serial)
671 n = n->rb_left;
672 else if (id > key->serial)
673 n = n->rb_right;
674 else
675 goto found;
676 }
677
678 not_found:
679 key = ERR_PTR(-ENOKEY);
680 goto error;
681
682 found:
683 /* A key is allowed to be looked up only if someone still owns a
684 * reference to it - otherwise it's awaiting the gc.
685 */
686 if (!refcount_inc_not_zero(&key->usage))
687 goto not_found;
688
689 error:
690 spin_unlock(&key_serial_lock);
691 return key;
692 }
693
694 /*
695 * Find and lock the specified key type against removal.
696 *
697 * We return with the sem read-locked if successful. If the type wasn't
698 * available -ENOKEY is returned instead.
699 */
key_type_lookup(const char * type)700 struct key_type *key_type_lookup(const char *type)
701 {
702 struct key_type *ktype;
703
704 down_read(&key_types_sem);
705
706 /* look up the key type to see if it's one of the registered kernel
707 * types */
708 list_for_each_entry(ktype, &key_types_list, link) {
709 if (strcmp(ktype->name, type) == 0)
710 goto found_kernel_type;
711 }
712
713 up_read(&key_types_sem);
714 ktype = ERR_PTR(-ENOKEY);
715
716 found_kernel_type:
717 return ktype;
718 }
719
key_set_timeout(struct key * key,unsigned timeout)720 void key_set_timeout(struct key *key, unsigned timeout)
721 {
722 time64_t expiry = TIME64_MAX;
723
724 /* make the changes with the locks held to prevent races */
725 down_write(&key->sem);
726
727 if (timeout > 0)
728 expiry = ktime_get_real_seconds() + timeout;
729 key_set_expiry(key, expiry);
730
731 up_write(&key->sem);
732 }
733 EXPORT_SYMBOL_GPL(key_set_timeout);
734
735 /*
736 * Unlock a key type locked by key_type_lookup().
737 */
key_type_put(struct key_type * ktype)738 void key_type_put(struct key_type *ktype)
739 {
740 up_read(&key_types_sem);
741 }
742
743 /*
744 * Attempt to update an existing key.
745 *
746 * The key is given to us with an incremented refcount that we need to discard
747 * if we get an error.
748 */
__key_update(key_ref_t key_ref,struct key_preparsed_payload * prep)749 static inline key_ref_t __key_update(key_ref_t key_ref,
750 struct key_preparsed_payload *prep)
751 {
752 struct key *key = key_ref_to_ptr(key_ref);
753 int ret;
754
755 /* need write permission on the key to update it */
756 ret = key_permission(key_ref, KEY_NEED_WRITE);
757 if (ret < 0)
758 goto error;
759
760 ret = -EEXIST;
761 if (!key->type->update)
762 goto error;
763
764 down_write(&key->sem);
765
766 ret = key->type->update(key, prep);
767 if (ret == 0) {
768 /* Updating a negative key positively instantiates it */
769 mark_key_instantiated(key, 0);
770 notify_key(key, NOTIFY_KEY_UPDATED, 0);
771 }
772
773 up_write(&key->sem);
774
775 if (ret < 0)
776 goto error;
777 out:
778 return key_ref;
779
780 error:
781 key_put(key);
782 key_ref = ERR_PTR(ret);
783 goto out;
784 }
785
786 /*
787 * Create or potentially update a key. The combined logic behind
788 * key_create_or_update() and key_create()
789 */
__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,bool allow_update)790 static key_ref_t __key_create_or_update(key_ref_t keyring_ref,
791 const char *type,
792 const char *description,
793 const void *payload,
794 size_t plen,
795 key_perm_t perm,
796 unsigned long flags,
797 bool allow_update)
798 {
799 struct keyring_index_key index_key = {
800 .description = description,
801 };
802 struct key_preparsed_payload prep;
803 struct assoc_array_edit *edit = NULL;
804 const struct cred *cred = current_cred();
805 struct key *keyring, *key = NULL;
806 key_ref_t key_ref;
807 int ret;
808 struct key_restriction *restrict_link = NULL;
809
810 /* look up the key type to see if it's one of the registered kernel
811 * types */
812 index_key.type = key_type_lookup(type);
813 if (IS_ERR(index_key.type)) {
814 key_ref = ERR_PTR(-ENODEV);
815 goto error;
816 }
817
818 key_ref = ERR_PTR(-EINVAL);
819 if (!index_key.type->instantiate ||
820 (!index_key.description && !index_key.type->preparse))
821 goto error_put_type;
822
823 keyring = key_ref_to_ptr(keyring_ref);
824
825 key_check(keyring);
826
827 if (!(flags & KEY_ALLOC_BYPASS_RESTRICTION))
828 restrict_link = keyring->restrict_link;
829
830 key_ref = ERR_PTR(-ENOTDIR);
831 if (keyring->type != &key_type_keyring)
832 goto error_put_type;
833
834 memset(&prep, 0, sizeof(prep));
835 prep.orig_description = description;
836 prep.data = payload;
837 prep.datalen = plen;
838 prep.quotalen = index_key.type->def_datalen;
839 prep.expiry = TIME64_MAX;
840 if (index_key.type->preparse) {
841 ret = index_key.type->preparse(&prep);
842 if (ret < 0) {
843 key_ref = ERR_PTR(ret);
844 goto error_free_prep;
845 }
846 if (!index_key.description)
847 index_key.description = prep.description;
848 key_ref = ERR_PTR(-EINVAL);
849 if (!index_key.description)
850 goto error_free_prep;
851 }
852 index_key.desc_len = strlen(index_key.description);
853 key_set_index_key(&index_key);
854
855 ret = __key_link_lock(keyring, &index_key);
856 if (ret < 0) {
857 key_ref = ERR_PTR(ret);
858 goto error_free_prep;
859 }
860
861 ret = __key_link_begin(keyring, &index_key, &edit);
862 if (ret < 0) {
863 key_ref = ERR_PTR(ret);
864 goto error_link_end;
865 }
866
867 if (restrict_link && restrict_link->check) {
868 ret = restrict_link->check(keyring, index_key.type,
869 &prep.payload, restrict_link->key);
870 if (ret < 0) {
871 key_ref = ERR_PTR(ret);
872 goto error_link_end;
873 }
874 }
875
876 /* if we're going to allocate a new key, we're going to have
877 * to modify the keyring */
878 ret = key_permission(keyring_ref, KEY_NEED_WRITE);
879 if (ret < 0) {
880 key_ref = ERR_PTR(ret);
881 goto error_link_end;
882 }
883
884 /* if it's requested and possible to update this type of key, search
885 * for an existing key of the same type and description in the
886 * destination keyring and update that instead if possible
887 */
888 if (allow_update) {
889 if (index_key.type->update) {
890 key_ref = find_key_to_update(keyring_ref, &index_key);
891 if (key_ref)
892 goto found_matching_key;
893 }
894 } else {
895 key_ref = find_key_to_update(keyring_ref, &index_key);
896 if (key_ref) {
897 key_ref_put(key_ref);
898 key_ref = ERR_PTR(-EEXIST);
899 goto error_link_end;
900 }
901 }
902
903 /* if the client doesn't provide, decide on the permissions we want */
904 if (perm == KEY_PERM_UNDEF) {
905 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
906 perm |= KEY_USR_VIEW;
907
908 if (index_key.type->read)
909 perm |= KEY_POS_READ;
910
911 if (index_key.type == &key_type_keyring ||
912 index_key.type->update)
913 perm |= KEY_POS_WRITE;
914 }
915
916 /* allocate a new key */
917 key = key_alloc(index_key.type, index_key.description,
918 cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
919 if (IS_ERR(key)) {
920 key_ref = ERR_CAST(key);
921 goto error_link_end;
922 }
923
924 /* instantiate it and link it into the target keyring */
925 ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
926 if (ret < 0) {
927 key_put(key);
928 key_ref = ERR_PTR(ret);
929 goto error_link_end;
930 }
931
932 ima_post_key_create_or_update(keyring, key, payload, plen,
933 flags, true);
934
935 key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
936
937 error_link_end:
938 __key_link_end(keyring, &index_key, edit);
939 error_free_prep:
940 if (index_key.type->preparse)
941 index_key.type->free_preparse(&prep);
942 error_put_type:
943 key_type_put(index_key.type);
944 error:
945 return key_ref;
946
947 found_matching_key:
948 /* we found a matching key, so we're going to try to update it
949 * - we can drop the locks first as we have the key pinned
950 */
951 __key_link_end(keyring, &index_key, edit);
952
953 key = key_ref_to_ptr(key_ref);
954 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) {
955 ret = wait_for_key_construction(key, true);
956 if (ret < 0) {
957 key_ref_put(key_ref);
958 key_ref = ERR_PTR(ret);
959 goto error_free_prep;
960 }
961 }
962
963 key_ref = __key_update(key_ref, &prep);
964
965 if (!IS_ERR(key_ref))
966 ima_post_key_create_or_update(keyring, key,
967 payload, plen,
968 flags, false);
969
970 goto error_free_prep;
971 }
972
973 /**
974 * key_create_or_update - Update or create and instantiate a key.
975 * @keyring_ref: A pointer to the destination keyring with possession flag.
976 * @type: The type of key.
977 * @description: The searchable description for the key.
978 * @payload: The data to use to instantiate or update the key.
979 * @plen: The length of @payload.
980 * @perm: The permissions mask for a new key.
981 * @flags: The quota flags for a new key.
982 *
983 * Search the destination keyring for a key of the same description and if one
984 * is found, update it, otherwise create and instantiate a new one and create a
985 * link to it from that keyring.
986 *
987 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
988 * concocted.
989 *
990 * Returns a pointer to the new key if successful, -ENODEV if the key type
991 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
992 * caller isn't permitted to modify the keyring or the LSM did not permit
993 * creation of the key.
994 *
995 * On success, the possession flag from the keyring ref will be tacked on to
996 * the key ref before it is returned.
997 */
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)998 key_ref_t key_create_or_update(key_ref_t keyring_ref,
999 const char *type,
1000 const char *description,
1001 const void *payload,
1002 size_t plen,
1003 key_perm_t perm,
1004 unsigned long flags)
1005 {
1006 return __key_create_or_update(keyring_ref, type, description, payload,
1007 plen, perm, flags, true);
1008 }
1009 EXPORT_SYMBOL(key_create_or_update);
1010
1011 /**
1012 * key_create - Create and instantiate a key.
1013 * @keyring_ref: A pointer to the destination keyring with possession flag.
1014 * @type: The type of key.
1015 * @description: The searchable description for the key.
1016 * @payload: The data to use to instantiate or update the key.
1017 * @plen: The length of @payload.
1018 * @perm: The permissions mask for a new key.
1019 * @flags: The quota flags for a new key.
1020 *
1021 * Create and instantiate a new key and link to it from the destination keyring.
1022 *
1023 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
1024 * concocted.
1025 *
1026 * Returns a pointer to the new key if successful, -EEXIST if a key with the
1027 * same description already exists, -ENODEV if the key type wasn't available,
1028 * -ENOTDIR if the keyring wasn't a keyring, -EACCES if the caller isn't
1029 * permitted to modify the keyring or the LSM did not permit creation of the
1030 * key.
1031 *
1032 * On success, the possession flag from the keyring ref will be tacked on to
1033 * the key ref before it is returned.
1034 */
key_create(key_ref_t keyring_ref,const char * type,const char * description,const void * payload,size_t plen,key_perm_t perm,unsigned long flags)1035 key_ref_t key_create(key_ref_t keyring_ref,
1036 const char *type,
1037 const char *description,
1038 const void *payload,
1039 size_t plen,
1040 key_perm_t perm,
1041 unsigned long flags)
1042 {
1043 return __key_create_or_update(keyring_ref, type, description, payload,
1044 plen, perm, flags, false);
1045 }
1046 EXPORT_SYMBOL(key_create);
1047
1048 /**
1049 * key_update - Update a key's contents.
1050 * @key_ref: The pointer (plus possession flag) to the key.
1051 * @payload: The data to be used to update the key.
1052 * @plen: The length of @payload.
1053 *
1054 * Attempt to update the contents of a key with the given payload data. The
1055 * caller must be granted Write permission on the key. Negative keys can be
1056 * instantiated by this method.
1057 *
1058 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
1059 * type does not support updating. The key type may return other errors.
1060 */
key_update(key_ref_t key_ref,const void * payload,size_t plen)1061 int key_update(key_ref_t key_ref, const void *payload, size_t plen)
1062 {
1063 struct key_preparsed_payload prep;
1064 struct key *key = key_ref_to_ptr(key_ref);
1065 int ret;
1066
1067 key_check(key);
1068
1069 /* the key must be writable */
1070 ret = key_permission(key_ref, KEY_NEED_WRITE);
1071 if (ret < 0)
1072 return ret;
1073
1074 /* attempt to update it if supported */
1075 if (!key->type->update)
1076 return -EOPNOTSUPP;
1077
1078 memset(&prep, 0, sizeof(prep));
1079 prep.data = payload;
1080 prep.datalen = plen;
1081 prep.quotalen = key->type->def_datalen;
1082 prep.expiry = TIME64_MAX;
1083 if (key->type->preparse) {
1084 ret = key->type->preparse(&prep);
1085 if (ret < 0)
1086 goto error;
1087 }
1088
1089 down_write(&key->sem);
1090
1091 ret = key->type->update(key, &prep);
1092 if (ret == 0) {
1093 /* Updating a negative key positively instantiates it */
1094 mark_key_instantiated(key, 0);
1095 notify_key(key, NOTIFY_KEY_UPDATED, 0);
1096 }
1097
1098 up_write(&key->sem);
1099
1100 error:
1101 if (key->type->preparse)
1102 key->type->free_preparse(&prep);
1103 return ret;
1104 }
1105 EXPORT_SYMBOL(key_update);
1106
1107 /**
1108 * key_revoke - Revoke a key.
1109 * @key: The key to be revoked.
1110 *
1111 * Mark a key as being revoked and ask the type to free up its resources. The
1112 * revocation timeout is set and the key and all its links will be
1113 * automatically garbage collected after key_gc_delay amount of time if they
1114 * are not manually dealt with first.
1115 */
key_revoke(struct key * key)1116 void key_revoke(struct key *key)
1117 {
1118 time64_t time;
1119
1120 key_check(key);
1121
1122 /* make sure no one's trying to change or use the key when we mark it
1123 * - we tell lockdep that we might nest because we might be revoking an
1124 * authorisation key whilst holding the sem on a key we've just
1125 * instantiated
1126 */
1127 down_write_nested(&key->sem, 1);
1128 if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags)) {
1129 notify_key(key, NOTIFY_KEY_REVOKED, 0);
1130 if (key->type->revoke)
1131 key->type->revoke(key);
1132
1133 /* set the death time to no more than the expiry time */
1134 time = ktime_get_real_seconds();
1135 if (key->revoked_at == 0 || key->revoked_at > time) {
1136 key->revoked_at = time;
1137 key_schedule_gc(key->revoked_at + key_gc_delay);
1138 }
1139 }
1140
1141 up_write(&key->sem);
1142 }
1143 EXPORT_SYMBOL(key_revoke);
1144
1145 /**
1146 * key_invalidate - Invalidate a key.
1147 * @key: The key to be invalidated.
1148 *
1149 * Mark a key as being invalidated and have it cleaned up immediately. The key
1150 * is ignored by all searches and other operations from this point.
1151 */
key_invalidate(struct key * key)1152 void key_invalidate(struct key *key)
1153 {
1154 kenter("%d", key_serial(key));
1155
1156 key_check(key);
1157
1158 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1159 down_write_nested(&key->sem, 1);
1160 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1161 notify_key(key, NOTIFY_KEY_INVALIDATED, 0);
1162 key_schedule_gc_links();
1163 }
1164 up_write(&key->sem);
1165 }
1166 }
1167 EXPORT_SYMBOL(key_invalidate);
1168
1169 /**
1170 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1171 * @key: The key to be instantiated
1172 * @prep: The preparsed data to load.
1173 *
1174 * Instantiate a key from preparsed data. We assume we can just copy the data
1175 * in directly and clear the old pointers.
1176 *
1177 * This can be pointed to directly by the key type instantiate op pointer.
1178 */
generic_key_instantiate(struct key * key,struct key_preparsed_payload * prep)1179 int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1180 {
1181 int ret;
1182
1183 pr_devel("==>%s()\n", __func__);
1184
1185 ret = key_payload_reserve(key, prep->quotalen);
1186 if (ret == 0) {
1187 rcu_assign_keypointer(key, prep->payload.data[0]);
1188 key->payload.data[1] = prep->payload.data[1];
1189 key->payload.data[2] = prep->payload.data[2];
1190 key->payload.data[3] = prep->payload.data[3];
1191 prep->payload.data[0] = NULL;
1192 prep->payload.data[1] = NULL;
1193 prep->payload.data[2] = NULL;
1194 prep->payload.data[3] = NULL;
1195 }
1196 pr_devel("<==%s() = %d\n", __func__, ret);
1197 return ret;
1198 }
1199 EXPORT_SYMBOL(generic_key_instantiate);
1200
1201 /**
1202 * register_key_type - Register a type of key.
1203 * @ktype: The new key type.
1204 *
1205 * Register a new key type.
1206 *
1207 * Returns 0 on success or -EEXIST if a type of this name already exists.
1208 */
register_key_type(struct key_type * ktype)1209 int register_key_type(struct key_type *ktype)
1210 {
1211 struct key_type *p;
1212 int ret;
1213
1214 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1215
1216 ret = -EEXIST;
1217 down_write(&key_types_sem);
1218
1219 /* disallow key types with the same name */
1220 list_for_each_entry(p, &key_types_list, link) {
1221 if (strcmp(p->name, ktype->name) == 0)
1222 goto out;
1223 }
1224
1225 /* store the type */
1226 list_add(&ktype->link, &key_types_list);
1227
1228 pr_notice("Key type %s registered\n", ktype->name);
1229 ret = 0;
1230
1231 out:
1232 up_write(&key_types_sem);
1233 return ret;
1234 }
1235 EXPORT_SYMBOL(register_key_type);
1236
1237 /**
1238 * unregister_key_type - Unregister a type of key.
1239 * @ktype: The key type.
1240 *
1241 * Unregister a key type and mark all the extant keys of this type as dead.
1242 * Those keys of this type are then destroyed to get rid of their payloads and
1243 * they and their links will be garbage collected as soon as possible.
1244 */
unregister_key_type(struct key_type * ktype)1245 void unregister_key_type(struct key_type *ktype)
1246 {
1247 down_write(&key_types_sem);
1248 list_del_init(&ktype->link);
1249 downgrade_write(&key_types_sem);
1250 key_gc_keytype(ktype);
1251 pr_notice("Key type %s unregistered\n", ktype->name);
1252 up_read(&key_types_sem);
1253 }
1254 EXPORT_SYMBOL(unregister_key_type);
1255
1256 /*
1257 * Initialise the key management state.
1258 */
key_init(void)1259 void __init key_init(void)
1260 {
1261 /* allocate a slab in which we can store keys */
1262 key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1263 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1264
1265 /* add the special key types */
1266 list_add_tail(&key_type_keyring.link, &key_types_list);
1267 list_add_tail(&key_type_dead.link, &key_types_list);
1268 list_add_tail(&key_type_user.link, &key_types_list);
1269 list_add_tail(&key_type_logon.link, &key_types_list);
1270
1271 /* record the root user tracking */
1272 rb_link_node(&root_key_user.node,
1273 NULL,
1274 &key_user_tree.rb_node);
1275
1276 rb_insert_color(&root_key_user.node,
1277 &key_user_tree);
1278 }
1279