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
20struct kmem_cache *key_jar;
21struct rb_root key_serial_tree; /* tree of keys indexed by serial */
22DEFINE_SPINLOCK(key_serial_lock);
23
24struct rb_root key_user_tree; /* tree of quota records indexed by UID */
25DEFINE_SPINLOCK(key_user_lock);
26
27unsigned int key_quota_root_maxkeys = 1000000; /* root's key count quota */
28unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
29unsigned int key_quota_maxkeys = 200; /* general key count quota */
30unsigned int key_quota_maxbytes = 20000; /* general key space quota */
31
32static LIST_HEAD(key_types_list);
33static DECLARE_RWSEM(key_types_sem);
34
35/* We serialise key instantiation and link */
36DEFINE_MUTEX(key_construction_mutex);
37
38#ifdef KEY_DEBUGGING
39void __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 */
51struct key_user *key_user_lookup(kuid_t uid)
52{
53 struct key_user *candidate = NULL, *user;
54 struct rb_node *parent, **p;
55
56try_again:
57 parent = NULL;
58 p = &key_user_tree.rb_node;
59 spin_lock(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(left: uid, right: user->uid))
67 p = &(*p)->rb_left;
68 else if (uid_gt(left: uid, right: 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(lock: &key_user_lock);
79
80 user = NULL;
81 candidate = kmalloc(size: 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(r: &candidate->usage, n: 1);
94 atomic_set(v: &candidate->nkeys, i: 0);
95 atomic_set(v: &candidate->nikeys, i: 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(node: &candidate->node, parent, rb_link: p);
103 rb_insert_color(&candidate->node, &key_user_tree);
104 spin_unlock(lock: &key_user_lock);
105 user = candidate;
106 goto out;
107
108 /* okay - we found a user record for this UID */
109found:
110 refcount_inc(r: &user->usage);
111 spin_unlock(lock: &key_user_lock);
112 kfree(objp: candidate);
113out:
114 return user;
115}
116
117/*
118 * Dispose of a user structure
119 */
120void key_user_put(struct key_user *user)
121{
122 if (refcount_dec_and_lock(r: &user->usage, lock: &key_user_lock)) {
123 rb_erase(&user->node, &key_user_tree);
124 spin_unlock(lock: &key_user_lock);
125
126 kfree(objp: 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 */
134static 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(buf: &key->serial, len: sizeof(key->serial));
143
144 key->serial >>= 1; /* negative numbers are not permitted */
145 } while (key->serial < 3);
146
147 spin_lock(lock: &key_serial_lock);
148
149attempt_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(node: &key->serial_node, parent, rb_link: p);
167 rb_insert_color(&key->serial_node, &key_serial_tree);
168
169 spin_unlock(lock: &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 */
174serial_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 */
225struct 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(error: -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(error: 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(left: uid, GLOBAL_ROOT_UID) ?
259 key_quota_root_maxkeys : key_quota_maxkeys;
260 unsigned maxbytes = uid_eq(left: uid, GLOBAL_ROOT_UID) ?
261 key_quota_root_maxbytes : key_quota_maxbytes;
262
263 spin_lock(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(lock: &user->lock);
274 }
275
276 /* allocate and initialise the key and its description */
277 key = kmem_cache_zalloc(k: 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(p: desc, size: 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(index_key: &key->index_key);
287
288 refcount_set(r: &key->usage, n: 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->restrict_link = restrict_link;
298 key->last_used_at = ktime_get_real_seconds();
299
300 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA))
301 key->flags |= 1 << KEY_FLAG_IN_QUOTA;
302 if (flags & KEY_ALLOC_BUILT_IN)
303 key->flags |= 1 << KEY_FLAG_BUILTIN;
304 if (flags & KEY_ALLOC_UID_KEYRING)
305 key->flags |= 1 << KEY_FLAG_UID_KEYRING;
306 if (flags & KEY_ALLOC_SET_KEEP)
307 key->flags |= 1 << KEY_FLAG_KEEP;
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 refcount_inc(r: &key->domain_tag->usage);
320 atomic_inc(v: &user->nkeys);
321 key_alloc_serial(key);
322
323error:
324 return key;
325
326security_error:
327 kfree(objp: key->description);
328 kmem_cache_free(s: key_jar, objp: key);
329 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
330 spin_lock(lock: &user->lock);
331 user->qnkeys--;
332 user->qnbytes -= quotalen;
333 spin_unlock(lock: &user->lock);
334 }
335 key_user_put(user);
336 key = ERR_PTR(error: ret);
337 goto error;
338
339no_memory_3:
340 kmem_cache_free(s: key_jar, objp: key);
341no_memory_2:
342 if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
343 spin_lock(lock: &user->lock);
344 user->qnkeys--;
345 user->qnbytes -= quotalen;
346 spin_unlock(lock: &user->lock);
347 }
348 key_user_put(user);
349no_memory_1:
350 key = ERR_PTR(error: -ENOMEM);
351 goto error;
352
353no_quota:
354 spin_unlock(lock: &user->lock);
355 key_user_put(user);
356 key = ERR_PTR(error: -EDQUOT);
357 goto error;
358}
359EXPORT_SYMBOL(key_alloc);
360
361/**
362 * key_payload_reserve - Adjust data quota reservation for the key's payload
363 * @key: The key to make the reservation for.
364 * @datalen: The amount of data payload the caller now wants.
365 *
366 * Adjust the amount of the owning user's key data quota that a key reserves.
367 * If the amount is increased, then -EDQUOT may be returned if there isn't
368 * enough free quota available.
369 *
370 * If successful, 0 is returned.
371 */
372int key_payload_reserve(struct key *key, size_t datalen)
373{
374 int delta = (int)datalen - key->datalen;
375 int ret = 0;
376
377 key_check(key);
378
379 /* contemplate the quota adjustment */
380 if (delta != 0 && test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
381 unsigned maxbytes = uid_eq(left: key->user->uid, GLOBAL_ROOT_UID) ?
382 key_quota_root_maxbytes : key_quota_maxbytes;
383
384 spin_lock(lock: &key->user->lock);
385
386 if (delta > 0 &&
387 (key->user->qnbytes + delta > maxbytes ||
388 key->user->qnbytes + delta < key->user->qnbytes)) {
389 ret = -EDQUOT;
390 }
391 else {
392 key->user->qnbytes += delta;
393 key->quotalen += delta;
394 }
395 spin_unlock(lock: &key->user->lock);
396 }
397
398 /* change the recorded data length if that didn't generate an error */
399 if (ret == 0)
400 key->datalen = datalen;
401
402 return ret;
403}
404EXPORT_SYMBOL(key_payload_reserve);
405
406/*
407 * Change the key state to being instantiated.
408 */
409static void mark_key_instantiated(struct key *key, int reject_error)
410{
411 /* Commit the payload before setting the state; barrier versus
412 * key_read_state().
413 */
414 smp_store_release(&key->state,
415 (reject_error < 0) ? reject_error : KEY_IS_POSITIVE);
416}
417
418/*
419 * Instantiate a key and link it into the target keyring atomically. Must be
420 * called with the target keyring's semaphore writelocked. The target key's
421 * semaphore need not be locked as instantiation is serialised by
422 * key_construction_mutex.
423 */
424static int __key_instantiate_and_link(struct key *key,
425 struct key_preparsed_payload *prep,
426 struct key *keyring,
427 struct key *authkey,
428 struct assoc_array_edit **_edit)
429{
430 int ret, awaken;
431
432 key_check(key);
433 key_check(keyring);
434
435 awaken = 0;
436 ret = -EBUSY;
437
438 mutex_lock(&key_construction_mutex);
439
440 /* can't instantiate twice */
441 if (key->state == KEY_IS_UNINSTANTIATED) {
442 /* instantiate the key */
443 ret = key->type->instantiate(key, prep);
444
445 if (ret == 0) {
446 /* mark the key as being instantiated */
447 atomic_inc(v: &key->user->nikeys);
448 mark_key_instantiated(key, reject_error: 0);
449 notify_key(key, subtype: NOTIFY_KEY_INSTANTIATED, aux: 0);
450
451 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, addr: &key->flags))
452 awaken = 1;
453
454 /* and link it into the destination keyring */
455 if (keyring) {
456 if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
457 set_bit(KEY_FLAG_KEEP, addr: &key->flags);
458
459 __key_link(keyring, key, _edit);
460 }
461
462 /* disable the authorisation key */
463 if (authkey)
464 key_invalidate(key: authkey);
465
466 if (prep->expiry != TIME64_MAX) {
467 key->expiry = prep->expiry;
468 key_schedule_gc(gc_at: prep->expiry + key_gc_delay);
469 }
470 }
471 }
472
473 mutex_unlock(lock: &key_construction_mutex);
474
475 /* wake up anyone waiting for a key to be constructed */
476 if (awaken)
477 wake_up_bit(word: &key->flags, KEY_FLAG_USER_CONSTRUCT);
478
479 return ret;
480}
481
482/**
483 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
484 * @key: The key to instantiate.
485 * @data: The data to use to instantiate the keyring.
486 * @datalen: The length of @data.
487 * @keyring: Keyring to create a link in on success (or NULL).
488 * @authkey: The authorisation token permitting instantiation.
489 *
490 * Instantiate a key that's in the uninstantiated state using the provided data
491 * and, if successful, link it in to the destination keyring if one is
492 * supplied.
493 *
494 * If successful, 0 is returned, the authorisation token is revoked and anyone
495 * waiting for the key is woken up. If the key was already instantiated,
496 * -EBUSY will be returned.
497 */
498int key_instantiate_and_link(struct key *key,
499 const void *data,
500 size_t datalen,
501 struct key *keyring,
502 struct key *authkey)
503{
504 struct key_preparsed_payload prep;
505 struct assoc_array_edit *edit = NULL;
506 int ret;
507
508 memset(&prep, 0, sizeof(prep));
509 prep.orig_description = key->description;
510 prep.data = data;
511 prep.datalen = datalen;
512 prep.quotalen = key->type->def_datalen;
513 prep.expiry = TIME64_MAX;
514 if (key->type->preparse) {
515 ret = key->type->preparse(&prep);
516 if (ret < 0)
517 goto error;
518 }
519
520 if (keyring) {
521 ret = __key_link_lock(keyring, index_key: &key->index_key);
522 if (ret < 0)
523 goto error;
524
525 ret = __key_link_begin(keyring, index_key: &key->index_key, edit: &edit);
526 if (ret < 0)
527 goto error_link_end;
528
529 if (keyring->restrict_link && keyring->restrict_link->check) {
530 struct key_restriction *keyres = keyring->restrict_link;
531
532 ret = keyres->check(keyring, key->type, &prep.payload,
533 keyres->key);
534 if (ret < 0)
535 goto error_link_end;
536 }
537 }
538
539 ret = __key_instantiate_and_link(key, prep: &prep, keyring, authkey, edit: &edit);
540
541error_link_end:
542 if (keyring)
543 __key_link_end(keyring, index_key: &key->index_key, edit);
544
545error:
546 if (key->type->preparse)
547 key->type->free_preparse(&prep);
548 return ret;
549}
550
551EXPORT_SYMBOL(key_instantiate_and_link);
552
553/**
554 * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
555 * @key: The key to instantiate.
556 * @timeout: The timeout on the negative key.
557 * @error: The error to return when the key is hit.
558 * @keyring: Keyring to create a link in on success (or NULL).
559 * @authkey: The authorisation token permitting instantiation.
560 *
561 * Negatively instantiate a key that's in the uninstantiated state and, if
562 * successful, set its timeout and stored error and link it in to the
563 * destination keyring if one is supplied. The key and any links to the key
564 * will be automatically garbage collected after the timeout expires.
565 *
566 * Negative keys are used to rate limit repeated request_key() calls by causing
567 * them to return the stored error code (typically ENOKEY) until the negative
568 * key expires.
569 *
570 * If successful, 0 is returned, the authorisation token is revoked and anyone
571 * waiting for the key is woken up. If the key was already instantiated,
572 * -EBUSY will be returned.
573 */
574int key_reject_and_link(struct key *key,
575 unsigned timeout,
576 unsigned error,
577 struct key *keyring,
578 struct key *authkey)
579{
580 struct assoc_array_edit *edit = NULL;
581 int ret, awaken, link_ret = 0;
582
583 key_check(key);
584 key_check(keyring);
585
586 awaken = 0;
587 ret = -EBUSY;
588
589 if (keyring) {
590 if (keyring->restrict_link)
591 return -EPERM;
592
593 link_ret = __key_link_lock(keyring, index_key: &key->index_key);
594 if (link_ret == 0) {
595 link_ret = __key_link_begin(keyring, index_key: &key->index_key, edit: &edit);
596 if (link_ret < 0)
597 __key_link_end(keyring, index_key: &key->index_key, edit);
598 }
599 }
600
601 mutex_lock(&key_construction_mutex);
602
603 /* can't instantiate twice */
604 if (key->state == KEY_IS_UNINSTANTIATED) {
605 /* mark the key as being negatively instantiated */
606 atomic_inc(v: &key->user->nikeys);
607 mark_key_instantiated(key, reject_error: -error);
608 notify_key(key, subtype: NOTIFY_KEY_INSTANTIATED, aux: -error);
609 key->expiry = ktime_get_real_seconds() + timeout;
610 key_schedule_gc(gc_at: key->expiry + key_gc_delay);
611
612 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, addr: &key->flags))
613 awaken = 1;
614
615 ret = 0;
616
617 /* and link it into the destination keyring */
618 if (keyring && link_ret == 0)
619 __key_link(keyring, key, edit: &edit);
620
621 /* disable the authorisation key */
622 if (authkey)
623 key_invalidate(key: authkey);
624 }
625
626 mutex_unlock(lock: &key_construction_mutex);
627
628 if (keyring && link_ret == 0)
629 __key_link_end(keyring, index_key: &key->index_key, edit);
630
631 /* wake up anyone waiting for a key to be constructed */
632 if (awaken)
633 wake_up_bit(word: &key->flags, KEY_FLAG_USER_CONSTRUCT);
634
635 return ret == 0 ? link_ret : ret;
636}
637EXPORT_SYMBOL(key_reject_and_link);
638
639/**
640 * key_put - Discard a reference to a key.
641 * @key: The key to discard a reference from.
642 *
643 * Discard a reference to a key, and when all the references are gone, we
644 * schedule the cleanup task to come and pull it out of the tree in process
645 * context at some later time.
646 */
647void key_put(struct key *key)
648{
649 if (key) {
650 key_check(key);
651
652 if (refcount_dec_and_test(r: &key->usage))
653 schedule_work(work: &key_gc_work);
654 }
655}
656EXPORT_SYMBOL(key_put);
657
658/*
659 * Find a key by its serial number.
660 */
661struct key *key_lookup(key_serial_t id)
662{
663 struct rb_node *n;
664 struct key *key;
665
666 spin_lock(lock: &key_serial_lock);
667
668 /* search the tree for the specified key */
669 n = key_serial_tree.rb_node;
670 while (n) {
671 key = rb_entry(n, struct key, serial_node);
672
673 if (id < key->serial)
674 n = n->rb_left;
675 else if (id > key->serial)
676 n = n->rb_right;
677 else
678 goto found;
679 }
680
681not_found:
682 key = ERR_PTR(error: -ENOKEY);
683 goto error;
684
685found:
686 /* A key is allowed to be looked up only if someone still owns a
687 * reference to it - otherwise it's awaiting the gc.
688 */
689 if (!refcount_inc_not_zero(r: &key->usage))
690 goto not_found;
691
692error:
693 spin_unlock(lock: &key_serial_lock);
694 return key;
695}
696EXPORT_SYMBOL(key_lookup);
697
698/*
699 * Find and lock the specified key type against removal.
700 *
701 * We return with the sem read-locked if successful. If the type wasn't
702 * available -ENOKEY is returned instead.
703 */
704struct key_type *key_type_lookup(const char *type)
705{
706 struct key_type *ktype;
707
708 down_read(sem: &key_types_sem);
709
710 /* look up the key type to see if it's one of the registered kernel
711 * types */
712 list_for_each_entry(ktype, &key_types_list, link) {
713 if (strcmp(ktype->name, type) == 0)
714 goto found_kernel_type;
715 }
716
717 up_read(sem: &key_types_sem);
718 ktype = ERR_PTR(error: -ENOKEY);
719
720found_kernel_type:
721 return ktype;
722}
723
724void key_set_timeout(struct key *key, unsigned timeout)
725{
726 time64_t expiry = 0;
727
728 /* make the changes with the locks held to prevent races */
729 down_write(sem: &key->sem);
730
731 if (timeout > 0)
732 expiry = ktime_get_real_seconds() + timeout;
733
734 key->expiry = expiry;
735 key_schedule_gc(gc_at: key->expiry + key_gc_delay);
736
737 up_write(sem: &key->sem);
738}
739EXPORT_SYMBOL_GPL(key_set_timeout);
740
741/*
742 * Unlock a key type locked by key_type_lookup().
743 */
744void key_type_put(struct key_type *ktype)
745{
746 up_read(sem: &key_types_sem);
747}
748
749/*
750 * Attempt to update an existing key.
751 *
752 * The key is given to us with an incremented refcount that we need to discard
753 * if we get an error.
754 */
755static inline key_ref_t __key_update(key_ref_t key_ref,
756 struct key_preparsed_payload *prep)
757{
758 struct key *key = key_ref_to_ptr(key_ref);
759 int ret;
760
761 /* need write permission on the key to update it */
762 ret = key_permission(key_ref, need_perm: KEY_NEED_WRITE);
763 if (ret < 0)
764 goto error;
765
766 ret = -EEXIST;
767 if (!key->type->update)
768 goto error;
769
770 down_write(sem: &key->sem);
771
772 ret = key->type->update(key, prep);
773 if (ret == 0) {
774 /* Updating a negative key positively instantiates it */
775 mark_key_instantiated(key, reject_error: 0);
776 notify_key(key, subtype: NOTIFY_KEY_UPDATED, aux: 0);
777 }
778
779 up_write(sem: &key->sem);
780
781 if (ret < 0)
782 goto error;
783out:
784 return key_ref;
785
786error:
787 key_put(key);
788 key_ref = ERR_PTR(error: ret);
789 goto out;
790}
791
792/*
793 * Create or potentially update a key. The combined logic behind
794 * key_create_or_update() and key_create()
795 */
796static key_ref_t __key_create_or_update(key_ref_t keyring_ref,
797 const char *type,
798 const char *description,
799 const void *payload,
800 size_t plen,
801 key_perm_t perm,
802 unsigned long flags,
803 bool allow_update)
804{
805 struct keyring_index_key index_key = {
806 .description = description,
807 };
808 struct key_preparsed_payload prep;
809 struct assoc_array_edit *edit = NULL;
810 const struct cred *cred = current_cred();
811 struct key *keyring, *key = NULL;
812 key_ref_t key_ref;
813 int ret;
814 struct key_restriction *restrict_link = NULL;
815
816 /* look up the key type to see if it's one of the registered kernel
817 * types */
818 index_key.type = key_type_lookup(type);
819 if (IS_ERR(ptr: index_key.type)) {
820 key_ref = ERR_PTR(error: -ENODEV);
821 goto error;
822 }
823
824 key_ref = ERR_PTR(error: -EINVAL);
825 if (!index_key.type->instantiate ||
826 (!index_key.description && !index_key.type->preparse))
827 goto error_put_type;
828
829 keyring = key_ref_to_ptr(key_ref: keyring_ref);
830
831 key_check(keyring);
832
833 if (!(flags & KEY_ALLOC_BYPASS_RESTRICTION))
834 restrict_link = keyring->restrict_link;
835
836 key_ref = ERR_PTR(error: -ENOTDIR);
837 if (keyring->type != &key_type_keyring)
838 goto error_put_type;
839
840 memset(&prep, 0, sizeof(prep));
841 prep.orig_description = description;
842 prep.data = payload;
843 prep.datalen = plen;
844 prep.quotalen = index_key.type->def_datalen;
845 prep.expiry = TIME64_MAX;
846 if (index_key.type->preparse) {
847 ret = index_key.type->preparse(&prep);
848 if (ret < 0) {
849 key_ref = ERR_PTR(error: ret);
850 goto error_free_prep;
851 }
852 if (!index_key.description)
853 index_key.description = prep.description;
854 key_ref = ERR_PTR(error: -EINVAL);
855 if (!index_key.description)
856 goto error_free_prep;
857 }
858 index_key.desc_len = strlen(index_key.description);
859 key_set_index_key(index_key: &index_key);
860
861 ret = __key_link_lock(keyring, index_key: &index_key);
862 if (ret < 0) {
863 key_ref = ERR_PTR(error: ret);
864 goto error_free_prep;
865 }
866
867 ret = __key_link_begin(keyring, index_key: &index_key, edit: &edit);
868 if (ret < 0) {
869 key_ref = ERR_PTR(error: ret);
870 goto error_link_end;
871 }
872
873 if (restrict_link && restrict_link->check) {
874 ret = restrict_link->check(keyring, index_key.type,
875 &prep.payload, restrict_link->key);
876 if (ret < 0) {
877 key_ref = ERR_PTR(error: ret);
878 goto error_link_end;
879 }
880 }
881
882 /* if we're going to allocate a new key, we're going to have
883 * to modify the keyring */
884 ret = key_permission(key_ref: keyring_ref, need_perm: KEY_NEED_WRITE);
885 if (ret < 0) {
886 key_ref = ERR_PTR(error: ret);
887 goto error_link_end;
888 }
889
890 /* if it's requested and possible to update this type of key, search
891 * for an existing key of the same type and description in the
892 * destination keyring and update that instead if possible
893 */
894 if (allow_update) {
895 if (index_key.type->update) {
896 key_ref = find_key_to_update(keyring_ref, index_key: &index_key);
897 if (key_ref)
898 goto found_matching_key;
899 }
900 } else {
901 key_ref = find_key_to_update(keyring_ref, index_key: &index_key);
902 if (key_ref) {
903 key_ref_put(key_ref);
904 key_ref = ERR_PTR(error: -EEXIST);
905 goto error_link_end;
906 }
907 }
908
909 /* if the client doesn't provide, decide on the permissions we want */
910 if (perm == KEY_PERM_UNDEF) {
911 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
912 perm |= KEY_USR_VIEW;
913
914 if (index_key.type->read)
915 perm |= KEY_POS_READ;
916
917 if (index_key.type == &key_type_keyring ||
918 index_key.type->update)
919 perm |= KEY_POS_WRITE;
920 }
921
922 /* allocate a new key */
923 key = key_alloc(index_key.type, index_key.description,
924 cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
925 if (IS_ERR(ptr: key)) {
926 key_ref = ERR_CAST(ptr: key);
927 goto error_link_end;
928 }
929
930 /* instantiate it and link it into the target keyring */
931 ret = __key_instantiate_and_link(key, prep: &prep, keyring, NULL, edit: &edit);
932 if (ret < 0) {
933 key_put(key);
934 key_ref = ERR_PTR(error: ret);
935 goto error_link_end;
936 }
937
938 ima_post_key_create_or_update(keyring, key, payload, plen,
939 flags, create: true);
940
941 key_ref = make_key_ref(key, possession: is_key_possessed(key_ref: keyring_ref));
942
943error_link_end:
944 __key_link_end(keyring, index_key: &index_key, edit);
945error_free_prep:
946 if (index_key.type->preparse)
947 index_key.type->free_preparse(&prep);
948error_put_type:
949 key_type_put(ktype: index_key.type);
950error:
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: &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, intr: true);
962 if (ret < 0) {
963 key_ref_put(key_ref);
964 key_ref = ERR_PTR(error: ret);
965 goto error_free_prep;
966 }
967 }
968
969 key_ref = __key_update(key_ref, prep: &prep);
970
971 if (!IS_ERR(ptr: key_ref))
972 ima_post_key_create_or_update(keyring, key,
973 payload, plen,
974 flags, create: false);
975
976 goto error_free_prep;
977}
978
979/**
980 * key_create_or_update - Update or create and instantiate a key.
981 * @keyring_ref: A pointer to the destination keyring with possession flag.
982 * @type: The type of key.
983 * @description: The searchable description for the key.
984 * @payload: The data to use to instantiate or update the key.
985 * @plen: The length of @payload.
986 * @perm: The permissions mask for a new key.
987 * @flags: The quota flags for a new key.
988 *
989 * Search the destination keyring for a key of the same description and if one
990 * is found, update it, otherwise create and instantiate a new one and create a
991 * link to it from that keyring.
992 *
993 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
994 * concocted.
995 *
996 * Returns a pointer to the new key if successful, -ENODEV if the key type
997 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
998 * caller isn't permitted to modify the keyring or the LSM did not permit
999 * creation of the key.
1000 *
1001 * On success, the possession flag from the keyring ref will be tacked on to
1002 * the key ref before it is returned.
1003 */
1004key_ref_t key_create_or_update(key_ref_t keyring_ref,
1005 const char *type,
1006 const char *description,
1007 const void *payload,
1008 size_t plen,
1009 key_perm_t perm,
1010 unsigned long flags)
1011{
1012 return __key_create_or_update(keyring_ref, type, description, payload,
1013 plen, perm, flags, allow_update: true);
1014}
1015EXPORT_SYMBOL(key_create_or_update);
1016
1017/**
1018 * key_create - Create and instantiate a key.
1019 * @keyring_ref: A pointer to the destination keyring with possession flag.
1020 * @type: The type of key.
1021 * @description: The searchable description for the key.
1022 * @payload: The data to use to instantiate or update the key.
1023 * @plen: The length of @payload.
1024 * @perm: The permissions mask for a new key.
1025 * @flags: The quota flags for a new key.
1026 *
1027 * Create and instantiate a new key and link to it from the destination keyring.
1028 *
1029 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
1030 * concocted.
1031 *
1032 * Returns a pointer to the new key if successful, -EEXIST if a key with the
1033 * same description already exists, -ENODEV if the key type wasn't available,
1034 * -ENOTDIR if the keyring wasn't a keyring, -EACCES if the caller isn't
1035 * permitted to modify the keyring or the LSM did not permit creation of the
1036 * key.
1037 *
1038 * On success, the possession flag from the keyring ref will be tacked on to
1039 * the key ref before it is returned.
1040 */
1041key_ref_t key_create(key_ref_t keyring_ref,
1042 const char *type,
1043 const char *description,
1044 const void *payload,
1045 size_t plen,
1046 key_perm_t perm,
1047 unsigned long flags)
1048{
1049 return __key_create_or_update(keyring_ref, type, description, payload,
1050 plen, perm, flags, allow_update: false);
1051}
1052EXPORT_SYMBOL(key_create);
1053
1054/**
1055 * key_update - Update a key's contents.
1056 * @key_ref: The pointer (plus possession flag) to the key.
1057 * @payload: The data to be used to update the key.
1058 * @plen: The length of @payload.
1059 *
1060 * Attempt to update the contents of a key with the given payload data. The
1061 * caller must be granted Write permission on the key. Negative keys can be
1062 * instantiated by this method.
1063 *
1064 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
1065 * type does not support updating. The key type may return other errors.
1066 */
1067int key_update(key_ref_t key_ref, const void *payload, size_t plen)
1068{
1069 struct key_preparsed_payload prep;
1070 struct key *key = key_ref_to_ptr(key_ref);
1071 int ret;
1072
1073 key_check(key);
1074
1075 /* the key must be writable */
1076 ret = key_permission(key_ref, need_perm: KEY_NEED_WRITE);
1077 if (ret < 0)
1078 return ret;
1079
1080 /* attempt to update it if supported */
1081 if (!key->type->update)
1082 return -EOPNOTSUPP;
1083
1084 memset(&prep, 0, sizeof(prep));
1085 prep.data = payload;
1086 prep.datalen = plen;
1087 prep.quotalen = key->type->def_datalen;
1088 prep.expiry = TIME64_MAX;
1089 if (key->type->preparse) {
1090 ret = key->type->preparse(&prep);
1091 if (ret < 0)
1092 goto error;
1093 }
1094
1095 down_write(sem: &key->sem);
1096
1097 ret = key->type->update(key, &prep);
1098 if (ret == 0) {
1099 /* Updating a negative key positively instantiates it */
1100 mark_key_instantiated(key, reject_error: 0);
1101 notify_key(key, subtype: NOTIFY_KEY_UPDATED, aux: 0);
1102 }
1103
1104 up_write(sem: &key->sem);
1105
1106error:
1107 if (key->type->preparse)
1108 key->type->free_preparse(&prep);
1109 return ret;
1110}
1111EXPORT_SYMBOL(key_update);
1112
1113/**
1114 * key_revoke - Revoke a key.
1115 * @key: The key to be revoked.
1116 *
1117 * Mark a key as being revoked and ask the type to free up its resources. The
1118 * revocation timeout is set and the key and all its links will be
1119 * automatically garbage collected after key_gc_delay amount of time if they
1120 * are not manually dealt with first.
1121 */
1122void key_revoke(struct key *key)
1123{
1124 time64_t time;
1125
1126 key_check(key);
1127
1128 /* make sure no one's trying to change or use the key when we mark it
1129 * - we tell lockdep that we might nest because we might be revoking an
1130 * authorisation key whilst holding the sem on a key we've just
1131 * instantiated
1132 */
1133 down_write_nested(sem: &key->sem, subclass: 1);
1134 if (!test_and_set_bit(KEY_FLAG_REVOKED, addr: &key->flags)) {
1135 notify_key(key, subtype: NOTIFY_KEY_REVOKED, aux: 0);
1136 if (key->type->revoke)
1137 key->type->revoke(key);
1138
1139 /* set the death time to no more than the expiry time */
1140 time = ktime_get_real_seconds();
1141 if (key->revoked_at == 0 || key->revoked_at > time) {
1142 key->revoked_at = time;
1143 key_schedule_gc(gc_at: key->revoked_at + key_gc_delay);
1144 }
1145 }
1146
1147 up_write(sem: &key->sem);
1148}
1149EXPORT_SYMBOL(key_revoke);
1150
1151/**
1152 * key_invalidate - Invalidate a key.
1153 * @key: The key to be invalidated.
1154 *
1155 * Mark a key as being invalidated and have it cleaned up immediately. The key
1156 * is ignored by all searches and other operations from this point.
1157 */
1158void key_invalidate(struct key *key)
1159{
1160 kenter("%d", key_serial(key));
1161
1162 key_check(key);
1163
1164 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1165 down_write_nested(sem: &key->sem, subclass: 1);
1166 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, addr: &key->flags)) {
1167 notify_key(key, subtype: NOTIFY_KEY_INVALIDATED, aux: 0);
1168 key_schedule_gc_links();
1169 }
1170 up_write(sem: &key->sem);
1171 }
1172}
1173EXPORT_SYMBOL(key_invalidate);
1174
1175/**
1176 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1177 * @key: The key to be instantiated
1178 * @prep: The preparsed data to load.
1179 *
1180 * Instantiate a key from preparsed data. We assume we can just copy the data
1181 * in directly and clear the old pointers.
1182 *
1183 * This can be pointed to directly by the key type instantiate op pointer.
1184 */
1185int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1186{
1187 int ret;
1188
1189 pr_devel("==>%s()\n", __func__);
1190
1191 ret = key_payload_reserve(key, prep->quotalen);
1192 if (ret == 0) {
1193 rcu_assign_keypointer(key, prep->payload.data[0]);
1194 key->payload.data[1] = prep->payload.data[1];
1195 key->payload.data[2] = prep->payload.data[2];
1196 key->payload.data[3] = prep->payload.data[3];
1197 prep->payload.data[0] = NULL;
1198 prep->payload.data[1] = NULL;
1199 prep->payload.data[2] = NULL;
1200 prep->payload.data[3] = NULL;
1201 }
1202 pr_devel("<==%s() = %d\n", __func__, ret);
1203 return ret;
1204}
1205EXPORT_SYMBOL(generic_key_instantiate);
1206
1207/**
1208 * register_key_type - Register a type of key.
1209 * @ktype: The new key type.
1210 *
1211 * Register a new key type.
1212 *
1213 * Returns 0 on success or -EEXIST if a type of this name already exists.
1214 */
1215int register_key_type(struct key_type *ktype)
1216{
1217 struct key_type *p;
1218 int ret;
1219
1220 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1221
1222 ret = -EEXIST;
1223 down_write(sem: &key_types_sem);
1224
1225 /* disallow key types with the same name */
1226 list_for_each_entry(p, &key_types_list, link) {
1227 if (strcmp(p->name, ktype->name) == 0)
1228 goto out;
1229 }
1230
1231 /* store the type */
1232 list_add(new: &ktype->link, head: &key_types_list);
1233
1234 pr_notice("Key type %s registered\n", ktype->name);
1235 ret = 0;
1236
1237out:
1238 up_write(sem: &key_types_sem);
1239 return ret;
1240}
1241EXPORT_SYMBOL(register_key_type);
1242
1243/**
1244 * unregister_key_type - Unregister a type of key.
1245 * @ktype: The key type.
1246 *
1247 * Unregister a key type and mark all the extant keys of this type as dead.
1248 * Those keys of this type are then destroyed to get rid of their payloads and
1249 * they and their links will be garbage collected as soon as possible.
1250 */
1251void unregister_key_type(struct key_type *ktype)
1252{
1253 down_write(sem: &key_types_sem);
1254 list_del_init(entry: &ktype->link);
1255 downgrade_write(sem: &key_types_sem);
1256 key_gc_keytype(ktype);
1257 pr_notice("Key type %s unregistered\n", ktype->name);
1258 up_read(sem: &key_types_sem);
1259}
1260EXPORT_SYMBOL(unregister_key_type);
1261
1262/*
1263 * Initialise the key management state.
1264 */
1265void __init key_init(void)
1266{
1267 /* allocate a slab in which we can store keys */
1268 key_jar = kmem_cache_create(name: "key_jar", size: sizeof(struct key),
1269 align: 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1270
1271 /* add the special key types */
1272 list_add_tail(new: &key_type_keyring.link, head: &key_types_list);
1273 list_add_tail(new: &key_type_dead.link, head: &key_types_list);
1274 list_add_tail(new: &key_type_user.link, head: &key_types_list);
1275 list_add_tail(new: &key_type_logon.link, head: &key_types_list);
1276
1277 /* record the root user tracking */
1278 rb_link_node(node: &root_key_user.node,
1279 NULL,
1280 rb_link: &key_user_tree.rb_node);
1281
1282 rb_insert_color(&root_key_user.node,
1283 &key_user_tree);
1284}
1285

source code of linux/security/keys/key.c