1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Basic authentication token and access key management
3 *
4 * Copyright (C) 2004-2008 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/export.h>
9#include <linux/init.h>
10#include <linux/poison.h>
11#include <linux/sched.h>
12#include <linux/slab.h>
13#include <linux/security.h>
14#include <linux/workqueue.h>
15#include <linux/random.h>
16#include <linux/err.h>
17#include "internal.h"
18
19struct kmem_cache *key_jar;
20struct rb_root key_serial_tree; /* tree of keys indexed by serial */
21DEFINE_SPINLOCK(key_serial_lock);
22
23struct rb_root key_user_tree; /* tree of quota records indexed by UID */
24DEFINE_SPINLOCK(key_user_lock);
25
26unsigned int key_quota_root_maxkeys = 1000000; /* root's key count quota */
27unsigned int key_quota_root_maxbytes = 25000000; /* root's key space quota */
28unsigned int key_quota_maxkeys = 200; /* general key count quota */
29unsigned int key_quota_maxbytes = 20000; /* general key space quota */
30
31static LIST_HEAD(key_types_list);
32static DECLARE_RWSEM(key_types_sem);
33
34/* We serialise key instantiation and link */
35DEFINE_MUTEX(key_construction_mutex);
36
37#ifdef KEY_DEBUGGING
38void __key_check(const struct key *key)
39{
40 printk("__key_check: key %p {%08x} should be {%08x}\n",
41 key, key->magic, KEY_DEBUG_MAGIC);
42 BUG();
43}
44#endif
45
46/*
47 * Get the key quota record for a user, allocating a new record if one doesn't
48 * already exist.
49 */
50struct key_user *key_user_lookup(kuid_t uid)
51{
52 struct key_user *candidate = NULL, *user;
53 struct rb_node *parent, **p;
54
55try_again:
56 parent = NULL;
57 p = &key_user_tree.rb_node;
58 spin_lock(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(left: uid, right: user->uid))
66 p = &(*p)->rb_left;
67 else if (uid_gt(left: uid, right: 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(lock: &key_user_lock);
78
79 user = NULL;
80 candidate = kmalloc(size: 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(r: &candidate->usage, n: 1);
93 atomic_set(v: &candidate->nkeys, i: 0);
94 atomic_set(v: &candidate->nikeys, i: 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(node: &candidate->node, parent, rb_link: p);
102 rb_insert_color(&candidate->node, &key_user_tree);
103 spin_unlock(lock: &key_user_lock);
104 user = candidate;
105 goto out;
106
107 /* okay - we found a user record for this UID */
108found:
109 refcount_inc(r: &user->usage);
110 spin_unlock(lock: &key_user_lock);
111 kfree(objp: candidate);
112out:
113 return user;
114}
115
116/*
117 * Dispose of a user structure
118 */
119void key_user_put(struct key_user *user)
120{
121 if (refcount_dec_and_lock(r: &user->usage, lock: &key_user_lock)) {
122 rb_erase(&user->node, &key_user_tree);
123 spin_unlock(lock: &key_user_lock);
124
125 kfree(objp: user);
126 }
127}
128
129/*
130 * Allocate a serial number for a key. These are assigned randomly to avoid
131 * security issues through covert channel problems.
132 */
133static inline void key_alloc_serial(struct key *key)
134{
135 struct rb_node *parent, **p;
136 struct key *xkey;
137
138 /* propose a random serial number and look for a hole for it in the
139 * serial number tree */
140 do {
141 get_random_bytes(buf: &key->serial, len: sizeof(key->serial));
142
143 key->serial >>= 1; /* negative numbers are not permitted */
144 } while (key->serial < 3);
145
146 spin_lock(lock: &key_serial_lock);
147
148attempt_insertion:
149 parent = NULL;
150 p = &key_serial_tree.rb_node;
151
152 while (*p) {
153 parent = *p;
154 xkey = rb_entry(parent, struct key, serial_node);
155
156 if (key->serial < xkey->serial)
157 p = &(*p)->rb_left;
158 else if (key->serial > xkey->serial)
159 p = &(*p)->rb_right;
160 else
161 goto serial_exists;
162 }
163
164 /* we've found a suitable hole - arrange for this key to occupy it */
165 rb_link_node(node: &key->serial_node, parent, rb_link: p);
166 rb_insert_color(&key->serial_node, &key_serial_tree);
167
168 spin_unlock(lock: &key_serial_lock);
169 return;
170
171 /* we found a key with the proposed serial number - walk the tree from
172 * that point looking for the next unused serial number */
173serial_exists:
174 for (;;) {
175 key->serial++;
176 if (key->serial < 3) {
177 key->serial = 3;
178 goto attempt_insertion;
179 }
180
181 parent = rb_next(parent);
182 if (!parent)
183 goto attempt_insertion;
184
185 xkey = rb_entry(parent, struct key, serial_node);
186 if (key->serial < xkey->serial)
187 goto attempt_insertion;
188 }
189}
190
191/**
192 * key_alloc - Allocate a key of the specified type.
193 * @type: The type of key to allocate.
194 * @desc: The key description to allow the key to be searched out.
195 * @uid: The owner of the new key.
196 * @gid: The group ID for the new key's group permissions.
197 * @cred: The credentials specifying UID namespace.
198 * @perm: The permissions mask of the new key.
199 * @flags: Flags specifying quota properties.
200 * @restrict_link: Optional link restriction for new keyrings.
201 *
202 * Allocate a key of the specified type with the attributes given. The key is
203 * returned in an uninstantiated state and the caller needs to instantiate the
204 * key before returning.
205 *
206 * The restrict_link structure (if not NULL) will be freed when the
207 * keyring is destroyed, so it must be dynamically allocated.
208 *
209 * The user's key count quota is updated to reflect the creation of the key and
210 * the user's key data quota has the default for the key type reserved. The
211 * instantiation function should amend this as necessary. If insufficient
212 * quota is available, -EDQUOT will be returned.
213 *
214 * The LSM security modules can prevent a key being created, in which case
215 * -EACCES will be returned.
216 *
217 * Returns a pointer to the new key if successful and an error code otherwise.
218 *
219 * Note that the caller needs to ensure the key type isn't uninstantiated.
220 * Internally this can be done by locking key_types_sem. Externally, this can
221 * be done by either never unregistering the key type, or making sure
222 * key_alloc() calls don't race with module unloading.
223 */
224struct key *key_alloc(struct key_type *type, const char *desc,
225 kuid_t uid, kgid_t gid, const struct cred *cred,
226 key_perm_t perm, unsigned long flags,
227 struct key_restriction *restrict_link)
228{
229 struct key_user *user = NULL;
230 struct key *key;
231 size_t desclen, quotalen;
232 int ret;
233
234 key = ERR_PTR(error: -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(error: 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(left: uid, GLOBAL_ROOT_UID) ?
258 key_quota_root_maxkeys : key_quota_maxkeys;
259 unsigned maxbytes = uid_eq(left: uid, GLOBAL_ROOT_UID) ?
260 key_quota_root_maxbytes : key_quota_maxbytes;
261
262 spin_lock(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(lock: &user->lock);
273 }
274
275 /* allocate and initialise the key and its description */
276 key = kmem_cache_zalloc(k: 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(p: desc, size: 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(index_key: &key->index_key);
286
287 refcount_set(r: &key->usage, n: 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->expiry = TIME64_MAX;
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 key_set_expiry(key, expiry: prep->expiry);
467 }
468 }
469
470 mutex_unlock(lock: &key_construction_mutex);
471
472 /* wake up anyone waiting for a key to be constructed */
473 if (awaken)
474 wake_up_bit(word: &key->flags, KEY_FLAG_USER_CONSTRUCT);
475
476 return ret;
477}
478
479/**
480 * key_instantiate_and_link - Instantiate a key and link it into the keyring.
481 * @key: The key to instantiate.
482 * @data: The data to use to instantiate the keyring.
483 * @datalen: The length of @data.
484 * @keyring: Keyring to create a link in on success (or NULL).
485 * @authkey: The authorisation token permitting instantiation.
486 *
487 * Instantiate a key that's in the uninstantiated state using the provided data
488 * and, if successful, link it in to the destination keyring if one is
489 * supplied.
490 *
491 * If successful, 0 is returned, the authorisation token is revoked and anyone
492 * waiting for the key is woken up. If the key was already instantiated,
493 * -EBUSY will be returned.
494 */
495int key_instantiate_and_link(struct key *key,
496 const void *data,
497 size_t datalen,
498 struct key *keyring,
499 struct key *authkey)
500{
501 struct key_preparsed_payload prep;
502 struct assoc_array_edit *edit = NULL;
503 int ret;
504
505 memset(&prep, 0, sizeof(prep));
506 prep.orig_description = key->description;
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, index_key: &key->index_key);
519 if (ret < 0)
520 goto error;
521
522 ret = __key_link_begin(keyring, index_key: &key->index_key, edit: &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: &prep, keyring, authkey, edit: &edit);
537
538error_link_end:
539 if (keyring)
540 __key_link_end(keyring, index_key: &key->index_key, edit);
541
542error:
543 if (key->type->preparse)
544 key->type->free_preparse(&prep);
545 return ret;
546}
547
548EXPORT_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 */
571int 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, index_key: &key->index_key);
591 if (link_ret == 0) {
592 link_ret = __key_link_begin(keyring, index_key: &key->index_key, edit: &edit);
593 if (link_ret < 0)
594 __key_link_end(keyring, index_key: &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(v: &key->user->nikeys);
604 mark_key_instantiated(key, reject_error: -error);
605 notify_key(key, subtype: NOTIFY_KEY_INSTANTIATED, aux: -error);
606 key_set_expiry(key, expiry: ktime_get_real_seconds() + timeout);
607
608 if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, addr: &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(keyring, key, edit: &edit);
616
617 /* disable the authorisation key */
618 if (authkey)
619 key_invalidate(key: authkey);
620 }
621
622 mutex_unlock(lock: &key_construction_mutex);
623
624 if (keyring && link_ret == 0)
625 __key_link_end(keyring, index_key: &key->index_key, edit);
626
627 /* wake up anyone waiting for a key to be constructed */
628 if (awaken)
629 wake_up_bit(word: &key->flags, KEY_FLAG_USER_CONSTRUCT);
630
631 return ret == 0 ? link_ret : ret;
632}
633EXPORT_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 */
643void key_put(struct key *key)
644{
645 if (key) {
646 key_check(key);
647
648 if (refcount_dec_and_test(r: &key->usage))
649 schedule_work(work: &key_gc_work);
650 }
651}
652EXPORT_SYMBOL(key_put);
653
654/*
655 * Find a key by its serial number.
656 */
657struct key *key_lookup(key_serial_t id)
658{
659 struct rb_node *n;
660 struct key *key;
661
662 spin_lock(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
677not_found:
678 key = ERR_PTR(error: -ENOKEY);
679 goto error;
680
681found:
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(r: &key->usage))
686 goto not_found;
687
688error:
689 spin_unlock(lock: &key_serial_lock);
690 return key;
691}
692EXPORT_SYMBOL(key_lookup);
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 */
700struct key_type *key_type_lookup(const char *type)
701{
702 struct key_type *ktype;
703
704 down_read(sem: &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(sem: &key_types_sem);
714 ktype = ERR_PTR(error: -ENOKEY);
715
716found_kernel_type:
717 return ktype;
718}
719
720void 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(sem: &key->sem);
726
727 if (timeout > 0)
728 expiry = ktime_get_real_seconds() + timeout;
729 key_set_expiry(key, expiry);
730
731 up_write(sem: &key->sem);
732}
733EXPORT_SYMBOL_GPL(key_set_timeout);
734
735/*
736 * Unlock a key type locked by key_type_lookup().
737 */
738void key_type_put(struct key_type *ktype)
739{
740 up_read(sem: &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 */
749static 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, need_perm: 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(sem: &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, reject_error: 0);
770 notify_key(key, subtype: NOTIFY_KEY_UPDATED, aux: 0);
771 }
772
773 up_write(sem: &key->sem);
774
775 if (ret < 0)
776 goto error;
777out:
778 return key_ref;
779
780error:
781 key_put(key);
782 key_ref = ERR_PTR(error: 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 */
790static 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(ptr: index_key.type)) {
814 key_ref = ERR_PTR(error: -ENODEV);
815 goto error;
816 }
817
818 key_ref = ERR_PTR(error: -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(key_ref: 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(error: -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(error: ret);
844 goto error_free_prep;
845 }
846 if (!index_key.description)
847 index_key.description = prep.description;
848 key_ref = ERR_PTR(error: -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: &index_key);
854
855 ret = __key_link_lock(keyring, index_key: &index_key);
856 if (ret < 0) {
857 key_ref = ERR_PTR(error: ret);
858 goto error_free_prep;
859 }
860
861 ret = __key_link_begin(keyring, index_key: &index_key, edit: &edit);
862 if (ret < 0) {
863 key_ref = ERR_PTR(error: 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(error: 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(key_ref: keyring_ref, need_perm: KEY_NEED_WRITE);
879 if (ret < 0) {
880 key_ref = ERR_PTR(error: 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: &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: &index_key);
896 if (key_ref) {
897 key_ref_put(key_ref);
898 key_ref = ERR_PTR(error: -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(ptr: key)) {
920 key_ref = ERR_CAST(ptr: 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: &prep, keyring, NULL, edit: &edit);
926 if (ret < 0) {
927 key_put(key);
928 key_ref = ERR_PTR(error: ret);
929 goto error_link_end;
930 }
931
932 security_key_post_create_or_update(keyring, key, payload, payload_len: plen, flags,
933 create: true);
934
935 key_ref = make_key_ref(key, possession: is_key_possessed(key_ref: keyring_ref));
936
937error_link_end:
938 __key_link_end(keyring, index_key: &index_key, edit);
939error_free_prep:
940 if (index_key.type->preparse)
941 index_key.type->free_preparse(&prep);
942error_put_type:
943 key_type_put(ktype: index_key.type);
944error:
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: &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, intr: true);
956 if (ret < 0) {
957 key_ref_put(key_ref);
958 key_ref = ERR_PTR(error: ret);
959 goto error_free_prep;
960 }
961 }
962
963 key_ref = __key_update(key_ref, prep: &prep);
964
965 if (!IS_ERR(ptr: key_ref))
966 security_key_post_create_or_update(keyring, key, payload, payload_len: plen,
967 flags, create: false);
968
969 goto error_free_prep;
970}
971
972/**
973 * key_create_or_update - Update or create and instantiate a key.
974 * @keyring_ref: A pointer to the destination keyring with possession flag.
975 * @type: The type of key.
976 * @description: The searchable description for the key.
977 * @payload: The data to use to instantiate or update the key.
978 * @plen: The length of @payload.
979 * @perm: The permissions mask for a new key.
980 * @flags: The quota flags for a new key.
981 *
982 * Search the destination keyring for a key of the same description and if one
983 * is found, update it, otherwise create and instantiate a new one and create a
984 * link to it from that keyring.
985 *
986 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
987 * concocted.
988 *
989 * Returns a pointer to the new key if successful, -ENODEV if the key type
990 * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
991 * caller isn't permitted to modify the keyring or the LSM did not permit
992 * creation of the key.
993 *
994 * On success, the possession flag from the keyring ref will be tacked on to
995 * the key ref before it is returned.
996 */
997key_ref_t key_create_or_update(key_ref_t keyring_ref,
998 const char *type,
999 const char *description,
1000 const void *payload,
1001 size_t plen,
1002 key_perm_t perm,
1003 unsigned long flags)
1004{
1005 return __key_create_or_update(keyring_ref, type, description, payload,
1006 plen, perm, flags, allow_update: true);
1007}
1008EXPORT_SYMBOL(key_create_or_update);
1009
1010/**
1011 * key_create - Create and instantiate a key.
1012 * @keyring_ref: A pointer to the destination keyring with possession flag.
1013 * @type: The type of key.
1014 * @description: The searchable description for the key.
1015 * @payload: The data to use to instantiate or update the key.
1016 * @plen: The length of @payload.
1017 * @perm: The permissions mask for a new key.
1018 * @flags: The quota flags for a new key.
1019 *
1020 * Create and instantiate a new key and link to it from the destination keyring.
1021 *
1022 * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
1023 * concocted.
1024 *
1025 * Returns a pointer to the new key if successful, -EEXIST if a key with the
1026 * same description already exists, -ENODEV if the key type wasn't available,
1027 * -ENOTDIR if the keyring wasn't a keyring, -EACCES if the caller isn't
1028 * permitted to modify the keyring or the LSM did not permit creation of the
1029 * key.
1030 *
1031 * On success, the possession flag from the keyring ref will be tacked on to
1032 * the key ref before it is returned.
1033 */
1034key_ref_t key_create(key_ref_t keyring_ref,
1035 const char *type,
1036 const char *description,
1037 const void *payload,
1038 size_t plen,
1039 key_perm_t perm,
1040 unsigned long flags)
1041{
1042 return __key_create_or_update(keyring_ref, type, description, payload,
1043 plen, perm, flags, allow_update: false);
1044}
1045EXPORT_SYMBOL(key_create);
1046
1047/**
1048 * key_update - Update a key's contents.
1049 * @key_ref: The pointer (plus possession flag) to the key.
1050 * @payload: The data to be used to update the key.
1051 * @plen: The length of @payload.
1052 *
1053 * Attempt to update the contents of a key with the given payload data. The
1054 * caller must be granted Write permission on the key. Negative keys can be
1055 * instantiated by this method.
1056 *
1057 * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
1058 * type does not support updating. The key type may return other errors.
1059 */
1060int key_update(key_ref_t key_ref, const void *payload, size_t plen)
1061{
1062 struct key_preparsed_payload prep;
1063 struct key *key = key_ref_to_ptr(key_ref);
1064 int ret;
1065
1066 key_check(key);
1067
1068 /* the key must be writable */
1069 ret = key_permission(key_ref, need_perm: KEY_NEED_WRITE);
1070 if (ret < 0)
1071 return ret;
1072
1073 /* attempt to update it if supported */
1074 if (!key->type->update)
1075 return -EOPNOTSUPP;
1076
1077 memset(&prep, 0, sizeof(prep));
1078 prep.data = payload;
1079 prep.datalen = plen;
1080 prep.quotalen = key->type->def_datalen;
1081 prep.expiry = TIME64_MAX;
1082 if (key->type->preparse) {
1083 ret = key->type->preparse(&prep);
1084 if (ret < 0)
1085 goto error;
1086 }
1087
1088 down_write(sem: &key->sem);
1089
1090 ret = key->type->update(key, &prep);
1091 if (ret == 0) {
1092 /* Updating a negative key positively instantiates it */
1093 mark_key_instantiated(key, reject_error: 0);
1094 notify_key(key, subtype: NOTIFY_KEY_UPDATED, aux: 0);
1095 }
1096
1097 up_write(sem: &key->sem);
1098
1099error:
1100 if (key->type->preparse)
1101 key->type->free_preparse(&prep);
1102 return ret;
1103}
1104EXPORT_SYMBOL(key_update);
1105
1106/**
1107 * key_revoke - Revoke a key.
1108 * @key: The key to be revoked.
1109 *
1110 * Mark a key as being revoked and ask the type to free up its resources. The
1111 * revocation timeout is set and the key and all its links will be
1112 * automatically garbage collected after key_gc_delay amount of time if they
1113 * are not manually dealt with first.
1114 */
1115void key_revoke(struct key *key)
1116{
1117 time64_t time;
1118
1119 key_check(key);
1120
1121 /* make sure no one's trying to change or use the key when we mark it
1122 * - we tell lockdep that we might nest because we might be revoking an
1123 * authorisation key whilst holding the sem on a key we've just
1124 * instantiated
1125 */
1126 down_write_nested(sem: &key->sem, subclass: 1);
1127 if (!test_and_set_bit(KEY_FLAG_REVOKED, addr: &key->flags)) {
1128 notify_key(key, subtype: NOTIFY_KEY_REVOKED, aux: 0);
1129 if (key->type->revoke)
1130 key->type->revoke(key);
1131
1132 /* set the death time to no more than the expiry time */
1133 time = ktime_get_real_seconds();
1134 if (key->revoked_at == 0 || key->revoked_at > time) {
1135 key->revoked_at = time;
1136 key_schedule_gc(gc_at: key->revoked_at + key_gc_delay);
1137 }
1138 }
1139
1140 up_write(sem: &key->sem);
1141}
1142EXPORT_SYMBOL(key_revoke);
1143
1144/**
1145 * key_invalidate - Invalidate a key.
1146 * @key: The key to be invalidated.
1147 *
1148 * Mark a key as being invalidated and have it cleaned up immediately. The key
1149 * is ignored by all searches and other operations from this point.
1150 */
1151void key_invalidate(struct key *key)
1152{
1153 kenter("%d", key_serial(key));
1154
1155 key_check(key);
1156
1157 if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1158 down_write_nested(sem: &key->sem, subclass: 1);
1159 if (!test_and_set_bit(KEY_FLAG_INVALIDATED, addr: &key->flags)) {
1160 notify_key(key, subtype: NOTIFY_KEY_INVALIDATED, aux: 0);
1161 key_schedule_gc_links();
1162 }
1163 up_write(sem: &key->sem);
1164 }
1165}
1166EXPORT_SYMBOL(key_invalidate);
1167
1168/**
1169 * generic_key_instantiate - Simple instantiation of a key from preparsed data
1170 * @key: The key to be instantiated
1171 * @prep: The preparsed data to load.
1172 *
1173 * Instantiate a key from preparsed data. We assume we can just copy the data
1174 * in directly and clear the old pointers.
1175 *
1176 * This can be pointed to directly by the key type instantiate op pointer.
1177 */
1178int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1179{
1180 int ret;
1181
1182 pr_devel("==>%s()\n", __func__);
1183
1184 ret = key_payload_reserve(key, prep->quotalen);
1185 if (ret == 0) {
1186 rcu_assign_keypointer(key, prep->payload.data[0]);
1187 key->payload.data[1] = prep->payload.data[1];
1188 key->payload.data[2] = prep->payload.data[2];
1189 key->payload.data[3] = prep->payload.data[3];
1190 prep->payload.data[0] = NULL;
1191 prep->payload.data[1] = NULL;
1192 prep->payload.data[2] = NULL;
1193 prep->payload.data[3] = NULL;
1194 }
1195 pr_devel("<==%s() = %d\n", __func__, ret);
1196 return ret;
1197}
1198EXPORT_SYMBOL(generic_key_instantiate);
1199
1200/**
1201 * register_key_type - Register a type of key.
1202 * @ktype: The new key type.
1203 *
1204 * Register a new key type.
1205 *
1206 * Returns 0 on success or -EEXIST if a type of this name already exists.
1207 */
1208int register_key_type(struct key_type *ktype)
1209{
1210 struct key_type *p;
1211 int ret;
1212
1213 memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1214
1215 ret = -EEXIST;
1216 down_write(sem: &key_types_sem);
1217
1218 /* disallow key types with the same name */
1219 list_for_each_entry(p, &key_types_list, link) {
1220 if (strcmp(p->name, ktype->name) == 0)
1221 goto out;
1222 }
1223
1224 /* store the type */
1225 list_add(new: &ktype->link, head: &key_types_list);
1226
1227 pr_notice("Key type %s registered\n", ktype->name);
1228 ret = 0;
1229
1230out:
1231 up_write(sem: &key_types_sem);
1232 return ret;
1233}
1234EXPORT_SYMBOL(register_key_type);
1235
1236/**
1237 * unregister_key_type - Unregister a type of key.
1238 * @ktype: The key type.
1239 *
1240 * Unregister a key type and mark all the extant keys of this type as dead.
1241 * Those keys of this type are then destroyed to get rid of their payloads and
1242 * they and their links will be garbage collected as soon as possible.
1243 */
1244void unregister_key_type(struct key_type *ktype)
1245{
1246 down_write(sem: &key_types_sem);
1247 list_del_init(entry: &ktype->link);
1248 downgrade_write(sem: &key_types_sem);
1249 key_gc_keytype(ktype);
1250 pr_notice("Key type %s unregistered\n", ktype->name);
1251 up_read(sem: &key_types_sem);
1252}
1253EXPORT_SYMBOL(unregister_key_type);
1254
1255/*
1256 * Initialise the key management state.
1257 */
1258void __init key_init(void)
1259{
1260 /* allocate a slab in which we can store keys */
1261 key_jar = kmem_cache_create(name: "key_jar", size: sizeof(struct key),
1262 align: 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1263
1264 /* add the special key types */
1265 list_add_tail(new: &key_type_keyring.link, head: &key_types_list);
1266 list_add_tail(new: &key_type_dead.link, head: &key_types_list);
1267 list_add_tail(new: &key_type_user.link, head: &key_types_list);
1268 list_add_tail(new: &key_type_logon.link, head: &key_types_list);
1269
1270 /* record the root user tracking */
1271 rb_link_node(node: &root_key_user.node,
1272 NULL,
1273 rb_link: &key_user_tree.rb_node);
1274
1275 rb_insert_color(&root_key_user.node,
1276 &key_user_tree);
1277}
1278

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