xref: /linux/security/keys/key.c (revision aec499c75cf8e0b599be4d559e6922b613085f8f)
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
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  */
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  */
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  */
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  */
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->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(&key->domain_tag->usage);
320 	atomic_inc(&user->nkeys);
321 	key_alloc_serial(key);
322 
323 error:
324 	return key;
325 
326 security_error:
327 	kfree(key->description);
328 	kmem_cache_free(key_jar, key);
329 	if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
330 		spin_lock(&user->lock);
331 		user->qnkeys--;
332 		user->qnbytes -= quotalen;
333 		spin_unlock(&user->lock);
334 	}
335 	key_user_put(user);
336 	key = ERR_PTR(ret);
337 	goto error;
338 
339 no_memory_3:
340 	kmem_cache_free(key_jar, key);
341 no_memory_2:
342 	if (!(flags & KEY_ALLOC_NOT_IN_QUOTA)) {
343 		spin_lock(&user->lock);
344 		user->qnkeys--;
345 		user->qnbytes -= quotalen;
346 		spin_unlock(&user->lock);
347 	}
348 	key_user_put(user);
349 no_memory_1:
350 	key = ERR_PTR(-ENOMEM);
351 	goto error;
352 
353 no_quota:
354 	spin_unlock(&user->lock);
355 	key_user_put(user);
356 	key = ERR_PTR(-EDQUOT);
357 	goto error;
358 }
359 EXPORT_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  */
372 int 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(key->user->uid, GLOBAL_ROOT_UID) ?
382 			key_quota_root_maxbytes : key_quota_maxbytes;
383 
384 		spin_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(&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 }
404 EXPORT_SYMBOL(key_payload_reserve);
405 
406 /*
407  * Change the key state to being instantiated.
408  */
409 static 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  */
424 static 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(&key->user->nikeys);
448 			mark_key_instantiated(key, 0);
449 			notify_key(key, NOTIFY_KEY_INSTANTIATED, 0);
450 
451 			if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &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, &key->flags);
458 
459 				__key_link(keyring, key, _edit);
460 			}
461 
462 			/* disable the authorisation key */
463 			if (authkey)
464 				key_invalidate(authkey);
465 
466 			if (prep->expiry != TIME64_MAX) {
467 				key->expiry = prep->expiry;
468 				key_schedule_gc(prep->expiry + key_gc_delay);
469 			}
470 		}
471 	}
472 
473 	mutex_unlock(&key_construction_mutex);
474 
475 	/* wake up anyone waiting for a key to be constructed */
476 	if (awaken)
477 		wake_up_bit(&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  */
498 int 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, &key->index_key);
522 		if (ret < 0)
523 			goto error;
524 
525 		ret = __key_link_begin(keyring, &key->index_key, &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, keyring, authkey, &edit);
540 
541 error_link_end:
542 	if (keyring)
543 		__key_link_end(keyring, &key->index_key, edit);
544 
545 error:
546 	if (key->type->preparse)
547 		key->type->free_preparse(&prep);
548 	return ret;
549 }
550 
551 EXPORT_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  */
574 int 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, &key->index_key);
594 		if (link_ret == 0) {
595 			link_ret = __key_link_begin(keyring, &key->index_key, &edit);
596 			if (link_ret < 0)
597 				__key_link_end(keyring, &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(&key->user->nikeys);
607 		mark_key_instantiated(key, -error);
608 		notify_key(key, NOTIFY_KEY_INSTANTIATED, -error);
609 		key->expiry = ktime_get_real_seconds() + timeout;
610 		key_schedule_gc(key->expiry + key_gc_delay);
611 
612 		if (test_and_clear_bit(KEY_FLAG_USER_CONSTRUCT, &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);
620 
621 		/* disable the authorisation key */
622 		if (authkey)
623 			key_invalidate(authkey);
624 	}
625 
626 	mutex_unlock(&key_construction_mutex);
627 
628 	if (keyring && link_ret == 0)
629 		__key_link_end(keyring, &key->index_key, edit);
630 
631 	/* wake up anyone waiting for a key to be constructed */
632 	if (awaken)
633 		wake_up_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT);
634 
635 	return ret == 0 ? link_ret : ret;
636 }
637 EXPORT_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  */
647 void key_put(struct key *key)
648 {
649 	if (key) {
650 		key_check(key);
651 
652 		if (refcount_dec_and_test(&key->usage))
653 			schedule_work(&key_gc_work);
654 	}
655 }
656 EXPORT_SYMBOL(key_put);
657 
658 /*
659  * Find a key by its serial number.
660  */
661 struct key *key_lookup(key_serial_t id)
662 {
663 	struct rb_node *n;
664 	struct key *key;
665 
666 	spin_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 
681 not_found:
682 	key = ERR_PTR(-ENOKEY);
683 	goto error;
684 
685 found:
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(&key->usage))
690 		goto not_found;
691 
692 error:
693 	spin_unlock(&key_serial_lock);
694 	return key;
695 }
696 
697 /*
698  * Find and lock the specified key type against removal.
699  *
700  * We return with the sem read-locked if successful.  If the type wasn't
701  * available -ENOKEY is returned instead.
702  */
703 struct key_type *key_type_lookup(const char *type)
704 {
705 	struct key_type *ktype;
706 
707 	down_read(&key_types_sem);
708 
709 	/* look up the key type to see if it's one of the registered kernel
710 	 * types */
711 	list_for_each_entry(ktype, &key_types_list, link) {
712 		if (strcmp(ktype->name, type) == 0)
713 			goto found_kernel_type;
714 	}
715 
716 	up_read(&key_types_sem);
717 	ktype = ERR_PTR(-ENOKEY);
718 
719 found_kernel_type:
720 	return ktype;
721 }
722 
723 void key_set_timeout(struct key *key, unsigned timeout)
724 {
725 	time64_t expiry = 0;
726 
727 	/* make the changes with the locks held to prevent races */
728 	down_write(&key->sem);
729 
730 	if (timeout > 0)
731 		expiry = ktime_get_real_seconds() + timeout;
732 
733 	key->expiry = expiry;
734 	key_schedule_gc(key->expiry + key_gc_delay);
735 
736 	up_write(&key->sem);
737 }
738 EXPORT_SYMBOL_GPL(key_set_timeout);
739 
740 /*
741  * Unlock a key type locked by key_type_lookup().
742  */
743 void key_type_put(struct key_type *ktype)
744 {
745 	up_read(&key_types_sem);
746 }
747 
748 /*
749  * Attempt to update an existing key.
750  *
751  * The key is given to us with an incremented refcount that we need to discard
752  * if we get an error.
753  */
754 static inline key_ref_t __key_update(key_ref_t key_ref,
755 				     struct key_preparsed_payload *prep)
756 {
757 	struct key *key = key_ref_to_ptr(key_ref);
758 	int ret;
759 
760 	/* need write permission on the key to update it */
761 	ret = key_permission(key_ref, KEY_NEED_WRITE);
762 	if (ret < 0)
763 		goto error;
764 
765 	ret = -EEXIST;
766 	if (!key->type->update)
767 		goto error;
768 
769 	down_write(&key->sem);
770 
771 	ret = key->type->update(key, prep);
772 	if (ret == 0) {
773 		/* Updating a negative key positively instantiates it */
774 		mark_key_instantiated(key, 0);
775 		notify_key(key, NOTIFY_KEY_UPDATED, 0);
776 	}
777 
778 	up_write(&key->sem);
779 
780 	if (ret < 0)
781 		goto error;
782 out:
783 	return key_ref;
784 
785 error:
786 	key_put(key);
787 	key_ref = ERR_PTR(ret);
788 	goto out;
789 }
790 
791 /**
792  * key_create_or_update - Update or create and instantiate a key.
793  * @keyring_ref: A pointer to the destination keyring with possession flag.
794  * @type: The type of key.
795  * @description: The searchable description for the key.
796  * @payload: The data to use to instantiate or update the key.
797  * @plen: The length of @payload.
798  * @perm: The permissions mask for a new key.
799  * @flags: The quota flags for a new key.
800  *
801  * Search the destination keyring for a key of the same description and if one
802  * is found, update it, otherwise create and instantiate a new one and create a
803  * link to it from that keyring.
804  *
805  * If perm is KEY_PERM_UNDEF then an appropriate key permissions mask will be
806  * concocted.
807  *
808  * Returns a pointer to the new key if successful, -ENODEV if the key type
809  * wasn't available, -ENOTDIR if the keyring wasn't a keyring, -EACCES if the
810  * caller isn't permitted to modify the keyring or the LSM did not permit
811  * creation of the key.
812  *
813  * On success, the possession flag from the keyring ref will be tacked on to
814  * the key ref before it is returned.
815  */
816 key_ref_t key_create_or_update(key_ref_t keyring_ref,
817 			       const char *type,
818 			       const char *description,
819 			       const void *payload,
820 			       size_t plen,
821 			       key_perm_t perm,
822 			       unsigned long flags)
823 {
824 	struct keyring_index_key index_key = {
825 		.description	= description,
826 	};
827 	struct key_preparsed_payload prep;
828 	struct assoc_array_edit *edit = NULL;
829 	const struct cred *cred = current_cred();
830 	struct key *keyring, *key = NULL;
831 	key_ref_t key_ref;
832 	int ret;
833 	struct key_restriction *restrict_link = NULL;
834 
835 	/* look up the key type to see if it's one of the registered kernel
836 	 * types */
837 	index_key.type = key_type_lookup(type);
838 	if (IS_ERR(index_key.type)) {
839 		key_ref = ERR_PTR(-ENODEV);
840 		goto error;
841 	}
842 
843 	key_ref = ERR_PTR(-EINVAL);
844 	if (!index_key.type->instantiate ||
845 	    (!index_key.description && !index_key.type->preparse))
846 		goto error_put_type;
847 
848 	keyring = key_ref_to_ptr(keyring_ref);
849 
850 	key_check(keyring);
851 
852 	if (!(flags & KEY_ALLOC_BYPASS_RESTRICTION))
853 		restrict_link = keyring->restrict_link;
854 
855 	key_ref = ERR_PTR(-ENOTDIR);
856 	if (keyring->type != &key_type_keyring)
857 		goto error_put_type;
858 
859 	memset(&prep, 0, sizeof(prep));
860 	prep.orig_description = description;
861 	prep.data = payload;
862 	prep.datalen = plen;
863 	prep.quotalen = index_key.type->def_datalen;
864 	prep.expiry = TIME64_MAX;
865 	if (index_key.type->preparse) {
866 		ret = index_key.type->preparse(&prep);
867 		if (ret < 0) {
868 			key_ref = ERR_PTR(ret);
869 			goto error_free_prep;
870 		}
871 		if (!index_key.description)
872 			index_key.description = prep.description;
873 		key_ref = ERR_PTR(-EINVAL);
874 		if (!index_key.description)
875 			goto error_free_prep;
876 	}
877 	index_key.desc_len = strlen(index_key.description);
878 	key_set_index_key(&index_key);
879 
880 	ret = __key_link_lock(keyring, &index_key);
881 	if (ret < 0) {
882 		key_ref = ERR_PTR(ret);
883 		goto error_free_prep;
884 	}
885 
886 	ret = __key_link_begin(keyring, &index_key, &edit);
887 	if (ret < 0) {
888 		key_ref = ERR_PTR(ret);
889 		goto error_link_end;
890 	}
891 
892 	if (restrict_link && restrict_link->check) {
893 		ret = restrict_link->check(keyring, index_key.type,
894 					   &prep.payload, restrict_link->key);
895 		if (ret < 0) {
896 			key_ref = ERR_PTR(ret);
897 			goto error_link_end;
898 		}
899 	}
900 
901 	/* if we're going to allocate a new key, we're going to have
902 	 * to modify the keyring */
903 	ret = key_permission(keyring_ref, KEY_NEED_WRITE);
904 	if (ret < 0) {
905 		key_ref = ERR_PTR(ret);
906 		goto error_link_end;
907 	}
908 
909 	/* if it's possible to update this type of key, search for an existing
910 	 * key of the same type and description in the destination keyring and
911 	 * update that instead if possible
912 	 */
913 	if (index_key.type->update) {
914 		key_ref = find_key_to_update(keyring_ref, &index_key);
915 		if (key_ref)
916 			goto found_matching_key;
917 	}
918 
919 	/* if the client doesn't provide, decide on the permissions we want */
920 	if (perm == KEY_PERM_UNDEF) {
921 		perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
922 		perm |= KEY_USR_VIEW;
923 
924 		if (index_key.type->read)
925 			perm |= KEY_POS_READ;
926 
927 		if (index_key.type == &key_type_keyring ||
928 		    index_key.type->update)
929 			perm |= KEY_POS_WRITE;
930 	}
931 
932 	/* allocate a new key */
933 	key = key_alloc(index_key.type, index_key.description,
934 			cred->fsuid, cred->fsgid, cred, perm, flags, NULL);
935 	if (IS_ERR(key)) {
936 		key_ref = ERR_CAST(key);
937 		goto error_link_end;
938 	}
939 
940 	/* instantiate it and link it into the target keyring */
941 	ret = __key_instantiate_and_link(key, &prep, keyring, NULL, &edit);
942 	if (ret < 0) {
943 		key_put(key);
944 		key_ref = ERR_PTR(ret);
945 		goto error_link_end;
946 	}
947 
948 	ima_post_key_create_or_update(keyring, key, payload, plen,
949 				      flags, true);
950 
951 	key_ref = make_key_ref(key, is_key_possessed(keyring_ref));
952 
953 error_link_end:
954 	__key_link_end(keyring, &index_key, edit);
955 error_free_prep:
956 	if (index_key.type->preparse)
957 		index_key.type->free_preparse(&prep);
958 error_put_type:
959 	key_type_put(index_key.type);
960 error:
961 	return key_ref;
962 
963  found_matching_key:
964 	/* we found a matching key, so we're going to try to update it
965 	 * - we can drop the locks first as we have the key pinned
966 	 */
967 	__key_link_end(keyring, &index_key, edit);
968 
969 	key = key_ref_to_ptr(key_ref);
970 	if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags)) {
971 		ret = wait_for_key_construction(key, true);
972 		if (ret < 0) {
973 			key_ref_put(key_ref);
974 			key_ref = ERR_PTR(ret);
975 			goto error_free_prep;
976 		}
977 	}
978 
979 	key_ref = __key_update(key_ref, &prep);
980 
981 	if (!IS_ERR(key_ref))
982 		ima_post_key_create_or_update(keyring, key,
983 					      payload, plen,
984 					      flags, false);
985 
986 	goto error_free_prep;
987 }
988 EXPORT_SYMBOL(key_create_or_update);
989 
990 /**
991  * key_update - Update a key's contents.
992  * @key_ref: The pointer (plus possession flag) to the key.
993  * @payload: The data to be used to update the key.
994  * @plen: The length of @payload.
995  *
996  * Attempt to update the contents of a key with the given payload data.  The
997  * caller must be granted Write permission on the key.  Negative keys can be
998  * instantiated by this method.
999  *
1000  * Returns 0 on success, -EACCES if not permitted and -EOPNOTSUPP if the key
1001  * type does not support updating.  The key type may return other errors.
1002  */
1003 int key_update(key_ref_t key_ref, const void *payload, size_t plen)
1004 {
1005 	struct key_preparsed_payload prep;
1006 	struct key *key = key_ref_to_ptr(key_ref);
1007 	int ret;
1008 
1009 	key_check(key);
1010 
1011 	/* the key must be writable */
1012 	ret = key_permission(key_ref, KEY_NEED_WRITE);
1013 	if (ret < 0)
1014 		return ret;
1015 
1016 	/* attempt to update it if supported */
1017 	if (!key->type->update)
1018 		return -EOPNOTSUPP;
1019 
1020 	memset(&prep, 0, sizeof(prep));
1021 	prep.data = payload;
1022 	prep.datalen = plen;
1023 	prep.quotalen = key->type->def_datalen;
1024 	prep.expiry = TIME64_MAX;
1025 	if (key->type->preparse) {
1026 		ret = key->type->preparse(&prep);
1027 		if (ret < 0)
1028 			goto error;
1029 	}
1030 
1031 	down_write(&key->sem);
1032 
1033 	ret = key->type->update(key, &prep);
1034 	if (ret == 0) {
1035 		/* Updating a negative key positively instantiates it */
1036 		mark_key_instantiated(key, 0);
1037 		notify_key(key, NOTIFY_KEY_UPDATED, 0);
1038 	}
1039 
1040 	up_write(&key->sem);
1041 
1042 error:
1043 	if (key->type->preparse)
1044 		key->type->free_preparse(&prep);
1045 	return ret;
1046 }
1047 EXPORT_SYMBOL(key_update);
1048 
1049 /**
1050  * key_revoke - Revoke a key.
1051  * @key: The key to be revoked.
1052  *
1053  * Mark a key as being revoked and ask the type to free up its resources.  The
1054  * revocation timeout is set and the key and all its links will be
1055  * automatically garbage collected after key_gc_delay amount of time if they
1056  * are not manually dealt with first.
1057  */
1058 void key_revoke(struct key *key)
1059 {
1060 	time64_t time;
1061 
1062 	key_check(key);
1063 
1064 	/* make sure no one's trying to change or use the key when we mark it
1065 	 * - we tell lockdep that we might nest because we might be revoking an
1066 	 *   authorisation key whilst holding the sem on a key we've just
1067 	 *   instantiated
1068 	 */
1069 	down_write_nested(&key->sem, 1);
1070 	if (!test_and_set_bit(KEY_FLAG_REVOKED, &key->flags)) {
1071 		notify_key(key, NOTIFY_KEY_REVOKED, 0);
1072 		if (key->type->revoke)
1073 			key->type->revoke(key);
1074 
1075 		/* set the death time to no more than the expiry time */
1076 		time = ktime_get_real_seconds();
1077 		if (key->revoked_at == 0 || key->revoked_at > time) {
1078 			key->revoked_at = time;
1079 			key_schedule_gc(key->revoked_at + key_gc_delay);
1080 		}
1081 	}
1082 
1083 	up_write(&key->sem);
1084 }
1085 EXPORT_SYMBOL(key_revoke);
1086 
1087 /**
1088  * key_invalidate - Invalidate a key.
1089  * @key: The key to be invalidated.
1090  *
1091  * Mark a key as being invalidated and have it cleaned up immediately.  The key
1092  * is ignored by all searches and other operations from this point.
1093  */
1094 void key_invalidate(struct key *key)
1095 {
1096 	kenter("%d", key_serial(key));
1097 
1098 	key_check(key);
1099 
1100 	if (!test_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1101 		down_write_nested(&key->sem, 1);
1102 		if (!test_and_set_bit(KEY_FLAG_INVALIDATED, &key->flags)) {
1103 			notify_key(key, NOTIFY_KEY_INVALIDATED, 0);
1104 			key_schedule_gc_links();
1105 		}
1106 		up_write(&key->sem);
1107 	}
1108 }
1109 EXPORT_SYMBOL(key_invalidate);
1110 
1111 /**
1112  * generic_key_instantiate - Simple instantiation of a key from preparsed data
1113  * @key: The key to be instantiated
1114  * @prep: The preparsed data to load.
1115  *
1116  * Instantiate a key from preparsed data.  We assume we can just copy the data
1117  * in directly and clear the old pointers.
1118  *
1119  * This can be pointed to directly by the key type instantiate op pointer.
1120  */
1121 int generic_key_instantiate(struct key *key, struct key_preparsed_payload *prep)
1122 {
1123 	int ret;
1124 
1125 	pr_devel("==>%s()\n", __func__);
1126 
1127 	ret = key_payload_reserve(key, prep->quotalen);
1128 	if (ret == 0) {
1129 		rcu_assign_keypointer(key, prep->payload.data[0]);
1130 		key->payload.data[1] = prep->payload.data[1];
1131 		key->payload.data[2] = prep->payload.data[2];
1132 		key->payload.data[3] = prep->payload.data[3];
1133 		prep->payload.data[0] = NULL;
1134 		prep->payload.data[1] = NULL;
1135 		prep->payload.data[2] = NULL;
1136 		prep->payload.data[3] = NULL;
1137 	}
1138 	pr_devel("<==%s() = %d\n", __func__, ret);
1139 	return ret;
1140 }
1141 EXPORT_SYMBOL(generic_key_instantiate);
1142 
1143 /**
1144  * register_key_type - Register a type of key.
1145  * @ktype: The new key type.
1146  *
1147  * Register a new key type.
1148  *
1149  * Returns 0 on success or -EEXIST if a type of this name already exists.
1150  */
1151 int register_key_type(struct key_type *ktype)
1152 {
1153 	struct key_type *p;
1154 	int ret;
1155 
1156 	memset(&ktype->lock_class, 0, sizeof(ktype->lock_class));
1157 
1158 	ret = -EEXIST;
1159 	down_write(&key_types_sem);
1160 
1161 	/* disallow key types with the same name */
1162 	list_for_each_entry(p, &key_types_list, link) {
1163 		if (strcmp(p->name, ktype->name) == 0)
1164 			goto out;
1165 	}
1166 
1167 	/* store the type */
1168 	list_add(&ktype->link, &key_types_list);
1169 
1170 	pr_notice("Key type %s registered\n", ktype->name);
1171 	ret = 0;
1172 
1173 out:
1174 	up_write(&key_types_sem);
1175 	return ret;
1176 }
1177 EXPORT_SYMBOL(register_key_type);
1178 
1179 /**
1180  * unregister_key_type - Unregister a type of key.
1181  * @ktype: The key type.
1182  *
1183  * Unregister a key type and mark all the extant keys of this type as dead.
1184  * Those keys of this type are then destroyed to get rid of their payloads and
1185  * they and their links will be garbage collected as soon as possible.
1186  */
1187 void unregister_key_type(struct key_type *ktype)
1188 {
1189 	down_write(&key_types_sem);
1190 	list_del_init(&ktype->link);
1191 	downgrade_write(&key_types_sem);
1192 	key_gc_keytype(ktype);
1193 	pr_notice("Key type %s unregistered\n", ktype->name);
1194 	up_read(&key_types_sem);
1195 }
1196 EXPORT_SYMBOL(unregister_key_type);
1197 
1198 /*
1199  * Initialise the key management state.
1200  */
1201 void __init key_init(void)
1202 {
1203 	/* allocate a slab in which we can store keys */
1204 	key_jar = kmem_cache_create("key_jar", sizeof(struct key),
1205 			0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1206 
1207 	/* add the special key types */
1208 	list_add_tail(&key_type_keyring.link, &key_types_list);
1209 	list_add_tail(&key_type_dead.link, &key_types_list);
1210 	list_add_tail(&key_type_user.link, &key_types_list);
1211 	list_add_tail(&key_type_logon.link, &key_types_list);
1212 
1213 	/* record the root user tracking */
1214 	rb_link_node(&root_key_user.node,
1215 		     NULL,
1216 		     &key_user_tree.rb_node);
1217 
1218 	rb_insert_color(&root_key_user.node,
1219 			&key_user_tree);
1220 }
1221