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1/* Keyring handling
2 *
3 * Copyright (C) 2004-2005, 2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/sched.h>
15#include <linux/slab.h>
16#include <linux/security.h>
17#include <linux/seq_file.h>
18#include <linux/err.h>
19#include <keys/keyring-type.h>
20#include <linux/uaccess.h>
21#include "internal.h"
22
23#define rcu_dereference_locked_keyring(keyring) \
24 (rcu_dereference_protected( \
25 (keyring)->payload.subscriptions, \
26 rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem)))
27
28#define KEY_LINK_FIXQUOTA 1UL
29
30/*
31 * When plumbing the depths of the key tree, this sets a hard limit
32 * set on how deep we're willing to go.
33 */
34#define KEYRING_SEARCH_MAX_DEPTH 6
35
36/*
37 * We keep all named keyrings in a hash to speed looking them up.
38 */
39#define KEYRING_NAME_HASH_SIZE (1 << 5)
40
41static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE];
42static DEFINE_RWLOCK(keyring_name_lock);
43
44static inline unsigned keyring_hash(const char *desc)
45{
46 unsigned bucket = 0;
47
48 for (; *desc; desc++)
49 bucket += (unsigned char)*desc;
50
51 return bucket & (KEYRING_NAME_HASH_SIZE - 1);
52}
53
54/*
55 * The keyring key type definition. Keyrings are simply keys of this type and
56 * can be treated as ordinary keys in addition to having their own special
57 * operations.
58 */
59static int keyring_instantiate(struct key *keyring,
60 const void *data, size_t datalen);
61static int keyring_match(const struct key *keyring, const void *criterion);
62static void keyring_revoke(struct key *keyring);
63static void keyring_destroy(struct key *keyring);
64static void keyring_describe(const struct key *keyring, struct seq_file *m);
65static long keyring_read(const struct key *keyring,
66 char __user *buffer, size_t buflen);
67
68struct key_type key_type_keyring = {
69 .name = "keyring",
70 .def_datalen = sizeof(struct keyring_list),
71 .instantiate = keyring_instantiate,
72 .match = keyring_match,
73 .revoke = keyring_revoke,
74 .destroy = keyring_destroy,
75 .describe = keyring_describe,
76 .read = keyring_read,
77};
78EXPORT_SYMBOL(key_type_keyring);
79
80/*
81 * Semaphore to serialise link/link calls to prevent two link calls in parallel
82 * introducing a cycle.
83 */
84static DECLARE_RWSEM(keyring_serialise_link_sem);
85
86/*
87 * Publish the name of a keyring so that it can be found by name (if it has
88 * one).
89 */
90static void keyring_publish_name(struct key *keyring)
91{
92 int bucket;
93
94 if (keyring->description) {
95 bucket = keyring_hash(keyring->description);
96
97 write_lock(&keyring_name_lock);
98
99 if (!keyring_name_hash[bucket].next)
100 INIT_LIST_HEAD(&keyring_name_hash[bucket]);
101
102 list_add_tail(&keyring->type_data.link,
103 &keyring_name_hash[bucket]);
104
105 write_unlock(&keyring_name_lock);
106 }
107}
108
109/*
110 * Initialise a keyring.
111 *
112 * Returns 0 on success, -EINVAL if given any data.
113 */
114static int keyring_instantiate(struct key *keyring,
115 const void *data, size_t datalen)
116{
117 int ret;
118
119 ret = -EINVAL;
120 if (datalen == 0) {
121 /* make the keyring available by name if it has one */
122 keyring_publish_name(keyring);
123 ret = 0;
124 }
125
126 return ret;
127}
128
129/*
130 * Match keyrings on their name
131 */
132static int keyring_match(const struct key *keyring, const void *description)
133{
134 return keyring->description &&
135 strcmp(keyring->description, description) == 0;
136}
137
138/*
139 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
140 * and dispose of its data.
141 */
142static void keyring_destroy(struct key *keyring)
143{
144 struct keyring_list *klist;
145 int loop;
146
147 if (keyring->description) {
148 write_lock(&keyring_name_lock);
149
150 if (keyring->type_data.link.next != NULL &&
151 !list_empty(&keyring->type_data.link))
152 list_del(&keyring->type_data.link);
153
154 write_unlock(&keyring_name_lock);
155 }
156
157 klist = rcu_dereference_check(keyring->payload.subscriptions,
158 atomic_read(&keyring->usage) == 0);
159 if (klist) {
160 for (loop = klist->nkeys - 1; loop >= 0; loop--)
161 key_put(klist->keys[loop]);
162 kfree(klist);
163 }
164}
165
166/*
167 * Describe a keyring for /proc.
168 */
169static void keyring_describe(const struct key *keyring, struct seq_file *m)
170{
171 struct keyring_list *klist;
172
173 if (keyring->description)
174 seq_puts(m, keyring->description);
175 else
176 seq_puts(m, "[anon]");
177
178 if (key_is_instantiated(keyring)) {
179 rcu_read_lock();
180 klist = rcu_dereference(keyring->payload.subscriptions);
181 if (klist)
182 seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys);
183 else
184 seq_puts(m, ": empty");
185 rcu_read_unlock();
186 }
187}
188
189/*
190 * Read a list of key IDs from the keyring's contents in binary form
191 *
192 * The keyring's semaphore is read-locked by the caller.
193 */
194static long keyring_read(const struct key *keyring,
195 char __user *buffer, size_t buflen)
196{
197 struct keyring_list *klist;
198 struct key *key;
199 size_t qty, tmp;
200 int loop, ret;
201
202 ret = 0;
203 klist = rcu_dereference_locked_keyring(keyring);
204 if (klist) {
205 /* calculate how much data we could return */
206 qty = klist->nkeys * sizeof(key_serial_t);
207
208 if (buffer && buflen > 0) {
209 if (buflen > qty)
210 buflen = qty;
211
212 /* copy the IDs of the subscribed keys into the
213 * buffer */
214 ret = -EFAULT;
215
216 for (loop = 0; loop < klist->nkeys; loop++) {
217 key = klist->keys[loop];
218
219 tmp = sizeof(key_serial_t);
220 if (tmp > buflen)
221 tmp = buflen;
222
223 if (copy_to_user(buffer,
224 &key->serial,
225 tmp) != 0)
226 goto error;
227
228 buflen -= tmp;
229 if (buflen == 0)
230 break;
231 buffer += tmp;
232 }
233 }
234
235 ret = qty;
236 }
237
238error:
239 return ret;
240}
241
242/*
243 * Allocate a keyring and link into the destination keyring.
244 */
245struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
246 const struct cred *cred, unsigned long flags,
247 struct key *dest)
248{
249 struct key *keyring;
250 int ret;
251
252 keyring = key_alloc(&key_type_keyring, description,
253 uid, gid, cred,
254 (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
255 flags);
256
257 if (!IS_ERR(keyring)) {
258 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
259 if (ret < 0) {
260 key_put(keyring);
261 keyring = ERR_PTR(ret);
262 }
263 }
264
265 return keyring;
266}
267
268/**
269 * keyring_search_aux - Search a keyring tree for a key matching some criteria
270 * @keyring_ref: A pointer to the keyring with possession indicator.
271 * @cred: The credentials to use for permissions checks.
272 * @type: The type of key to search for.
273 * @description: Parameter for @match.
274 * @match: Function to rule on whether or not a key is the one required.
275 * @no_state_check: Don't check if a matching key is bad
276 *
277 * Search the supplied keyring tree for a key that matches the criteria given.
278 * The root keyring and any linked keyrings must grant Search permission to the
279 * caller to be searchable and keys can only be found if they too grant Search
280 * to the caller. The possession flag on the root keyring pointer controls use
281 * of the possessor bits in permissions checking of the entire tree. In
282 * addition, the LSM gets to forbid keyring searches and key matches.
283 *
284 * The search is performed as a breadth-then-depth search up to the prescribed
285 * limit (KEYRING_SEARCH_MAX_DEPTH).
286 *
287 * Keys are matched to the type provided and are then filtered by the match
288 * function, which is given the description to use in any way it sees fit. The
289 * match function may use any attributes of a key that it wishes to to
290 * determine the match. Normally the match function from the key type would be
291 * used.
292 *
293 * RCU is used to prevent the keyring key lists from disappearing without the
294 * need to take lots of locks.
295 *
296 * Returns a pointer to the found key and increments the key usage count if
297 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
298 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
299 * specified keyring wasn't a keyring.
300 *
301 * In the case of a successful return, the possession attribute from
302 * @keyring_ref is propagated to the returned key reference.
303 */
304key_ref_t keyring_search_aux(key_ref_t keyring_ref,
305 const struct cred *cred,
306 struct key_type *type,
307 const void *description,
308 key_match_func_t match,
309 bool no_state_check)
310{
311 struct {
312 struct keyring_list *keylist;
313 int kix;
314 } stack[KEYRING_SEARCH_MAX_DEPTH];
315
316 struct keyring_list *keylist;
317 struct timespec now;
318 unsigned long possessed, kflags;
319 struct key *keyring, *key;
320 key_ref_t key_ref;
321 long err;
322 int sp, kix;
323
324 keyring = key_ref_to_ptr(keyring_ref);
325 possessed = is_key_possessed(keyring_ref);
326 key_check(keyring);
327
328 /* top keyring must have search permission to begin the search */
329 err = key_task_permission(keyring_ref, cred, KEY_SEARCH);
330 if (err < 0) {
331 key_ref = ERR_PTR(err);
332 goto error;
333 }
334
335 key_ref = ERR_PTR(-ENOTDIR);
336 if (keyring->type != &key_type_keyring)
337 goto error;
338
339 rcu_read_lock();
340
341 now = current_kernel_time();
342 err = -EAGAIN;
343 sp = 0;
344
345 /* firstly we should check to see if this top-level keyring is what we
346 * are looking for */
347 key_ref = ERR_PTR(-EAGAIN);
348 kflags = keyring->flags;
349 if (keyring->type == type && match(keyring, description)) {
350 key = keyring;
351 if (no_state_check)
352 goto found;
353
354 /* check it isn't negative and hasn't expired or been
355 * revoked */
356 if (kflags & (1 << KEY_FLAG_REVOKED))
357 goto error_2;
358 if (key->expiry && now.tv_sec >= key->expiry)
359 goto error_2;
360 key_ref = ERR_PTR(key->type_data.reject_error);
361 if (kflags & (1 << KEY_FLAG_NEGATIVE))
362 goto error_2;
363 goto found;
364 }
365
366 /* otherwise, the top keyring must not be revoked, expired, or
367 * negatively instantiated if we are to search it */
368 key_ref = ERR_PTR(-EAGAIN);
369 if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) ||
370 (keyring->expiry && now.tv_sec >= keyring->expiry))
371 goto error_2;
372
373 /* start processing a new keyring */
374descend:
375 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
376 goto not_this_keyring;
377
378 keylist = rcu_dereference(keyring->payload.subscriptions);
379 if (!keylist)
380 goto not_this_keyring;
381
382 /* iterate through the keys in this keyring first */
383 for (kix = 0; kix < keylist->nkeys; kix++) {
384 key = keylist->keys[kix];
385 kflags = key->flags;
386
387 /* ignore keys not of this type */
388 if (key->type != type)
389 continue;
390
391 /* skip revoked keys and expired keys */
392 if (!no_state_check) {
393 if (kflags & (1 << KEY_FLAG_REVOKED))
394 continue;
395
396 if (key->expiry && now.tv_sec >= key->expiry)
397 continue;
398 }
399
400 /* keys that don't match */
401 if (!match(key, description))
402 continue;
403
404 /* key must have search permissions */
405 if (key_task_permission(make_key_ref(key, possessed),
406 cred, KEY_SEARCH) < 0)
407 continue;
408
409 if (no_state_check)
410 goto found;
411
412 /* we set a different error code if we pass a negative key */
413 if (kflags & (1 << KEY_FLAG_NEGATIVE)) {
414 err = key->type_data.reject_error;
415 continue;
416 }
417
418 goto found;
419 }
420
421 /* search through the keyrings nested in this one */
422 kix = 0;
423ascend:
424 for (; kix < keylist->nkeys; kix++) {
425 key = keylist->keys[kix];
426 if (key->type != &key_type_keyring)
427 continue;
428
429 /* recursively search nested keyrings
430 * - only search keyrings for which we have search permission
431 */
432 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
433 continue;
434
435 if (key_task_permission(make_key_ref(key, possessed),
436 cred, KEY_SEARCH) < 0)
437 continue;
438
439 /* stack the current position */
440 stack[sp].keylist = keylist;
441 stack[sp].kix = kix;
442 sp++;
443
444 /* begin again with the new keyring */
445 keyring = key;
446 goto descend;
447 }
448
449 /* the keyring we're looking at was disqualified or didn't contain a
450 * matching key */
451not_this_keyring:
452 if (sp > 0) {
453 /* resume the processing of a keyring higher up in the tree */
454 sp--;
455 keylist = stack[sp].keylist;
456 kix = stack[sp].kix + 1;
457 goto ascend;
458 }
459
460 key_ref = ERR_PTR(err);
461 goto error_2;
462
463 /* we found a viable match */
464found:
465 atomic_inc(&key->usage);
466 key_check(key);
467 key_ref = make_key_ref(key, possessed);
468error_2:
469 rcu_read_unlock();
470error:
471 return key_ref;
472}
473
474/**
475 * keyring_search - Search the supplied keyring tree for a matching key
476 * @keyring: The root of the keyring tree to be searched.
477 * @type: The type of keyring we want to find.
478 * @description: The name of the keyring we want to find.
479 *
480 * As keyring_search_aux() above, but using the current task's credentials and
481 * type's default matching function.
482 */
483key_ref_t keyring_search(key_ref_t keyring,
484 struct key_type *type,
485 const char *description)
486{
487 if (!type->match)
488 return ERR_PTR(-ENOKEY);
489
490 return keyring_search_aux(keyring, current->cred,
491 type, description, type->match, false);
492}
493EXPORT_SYMBOL(keyring_search);
494
495/*
496 * Search the given keyring only (no recursion).
497 *
498 * The caller must guarantee that the keyring is a keyring and that the
499 * permission is granted to search the keyring as no check is made here.
500 *
501 * RCU is used to make it unnecessary to lock the keyring key list here.
502 *
503 * Returns a pointer to the found key with usage count incremented if
504 * successful and returns -ENOKEY if not found. Revoked keys and keys not
505 * providing the requested permission are skipped over.
506 *
507 * If successful, the possession indicator is propagated from the keyring ref
508 * to the returned key reference.
509 */
510key_ref_t __keyring_search_one(key_ref_t keyring_ref,
511 const struct key_type *ktype,
512 const char *description,
513 key_perm_t perm)
514{
515 struct keyring_list *klist;
516 unsigned long possessed;
517 struct key *keyring, *key;
518 int loop;
519
520 keyring = key_ref_to_ptr(keyring_ref);
521 possessed = is_key_possessed(keyring_ref);
522
523 rcu_read_lock();
524
525 klist = rcu_dereference(keyring->payload.subscriptions);
526 if (klist) {
527 for (loop = 0; loop < klist->nkeys; loop++) {
528 key = klist->keys[loop];
529
530 if (key->type == ktype &&
531 (!key->type->match ||
532 key->type->match(key, description)) &&
533 key_permission(make_key_ref(key, possessed),
534 perm) == 0 &&
535 !test_bit(KEY_FLAG_REVOKED, &key->flags)
536 )
537 goto found;
538 }
539 }
540
541 rcu_read_unlock();
542 return ERR_PTR(-ENOKEY);
543
544found:
545 atomic_inc(&key->usage);
546 rcu_read_unlock();
547 return make_key_ref(key, possessed);
548}
549
550/*
551 * Find a keyring with the specified name.
552 *
553 * All named keyrings in the current user namespace are searched, provided they
554 * grant Search permission directly to the caller (unless this check is
555 * skipped). Keyrings whose usage points have reached zero or who have been
556 * revoked are skipped.
557 *
558 * Returns a pointer to the keyring with the keyring's refcount having being
559 * incremented on success. -ENOKEY is returned if a key could not be found.
560 */
561struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
562{
563 struct key *keyring;
564 int bucket;
565
566 if (!name)
567 return ERR_PTR(-EINVAL);
568
569 bucket = keyring_hash(name);
570
571 read_lock(&keyring_name_lock);
572
573 if (keyring_name_hash[bucket].next) {
574 /* search this hash bucket for a keyring with a matching name
575 * that's readable and that hasn't been revoked */
576 list_for_each_entry(keyring,
577 &keyring_name_hash[bucket],
578 type_data.link
579 ) {
580 if (keyring->user->user_ns != current_user_ns())
581 continue;
582
583 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
584 continue;
585
586 if (strcmp(keyring->description, name) != 0)
587 continue;
588
589 if (!skip_perm_check &&
590 key_permission(make_key_ref(keyring, 0),
591 KEY_SEARCH) < 0)
592 continue;
593
594 /* we've got a match but we might end up racing with
595 * key_cleanup() if the keyring is currently 'dead'
596 * (ie. it has a zero usage count) */
597 if (!atomic_inc_not_zero(&keyring->usage))
598 continue;
599 goto out;
600 }
601 }
602
603 keyring = ERR_PTR(-ENOKEY);
604out:
605 read_unlock(&keyring_name_lock);
606 return keyring;
607}
608
609/*
610 * See if a cycle will will be created by inserting acyclic tree B in acyclic
611 * tree A at the topmost level (ie: as a direct child of A).
612 *
613 * Since we are adding B to A at the top level, checking for cycles should just
614 * be a matter of seeing if node A is somewhere in tree B.
615 */
616static int keyring_detect_cycle(struct key *A, struct key *B)
617{
618 struct {
619 struct keyring_list *keylist;
620 int kix;
621 } stack[KEYRING_SEARCH_MAX_DEPTH];
622
623 struct keyring_list *keylist;
624 struct key *subtree, *key;
625 int sp, kix, ret;
626
627 rcu_read_lock();
628
629 ret = -EDEADLK;
630 if (A == B)
631 goto cycle_detected;
632
633 subtree = B;
634 sp = 0;
635
636 /* start processing a new keyring */
637descend:
638 if (test_bit(KEY_FLAG_REVOKED, &subtree->flags))
639 goto not_this_keyring;
640
641 keylist = rcu_dereference(subtree->payload.subscriptions);
642 if (!keylist)
643 goto not_this_keyring;
644 kix = 0;
645
646ascend:
647 /* iterate through the remaining keys in this keyring */
648 for (; kix < keylist->nkeys; kix++) {
649 key = keylist->keys[kix];
650
651 if (key == A)
652 goto cycle_detected;
653
654 /* recursively check nested keyrings */
655 if (key->type == &key_type_keyring) {
656 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
657 goto too_deep;
658
659 /* stack the current position */
660 stack[sp].keylist = keylist;
661 stack[sp].kix = kix;
662 sp++;
663
664 /* begin again with the new keyring */
665 subtree = key;
666 goto descend;
667 }
668 }
669
670 /* the keyring we're looking at was disqualified or didn't contain a
671 * matching key */
672not_this_keyring:
673 if (sp > 0) {
674 /* resume the checking of a keyring higher up in the tree */
675 sp--;
676 keylist = stack[sp].keylist;
677 kix = stack[sp].kix + 1;
678 goto ascend;
679 }
680
681 ret = 0; /* no cycles detected */
682
683error:
684 rcu_read_unlock();
685 return ret;
686
687too_deep:
688 ret = -ELOOP;
689 goto error;
690
691cycle_detected:
692 ret = -EDEADLK;
693 goto error;
694}
695
696/*
697 * Dispose of a keyring list after the RCU grace period, freeing the unlinked
698 * key
699 */
700static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
701{
702 struct keyring_list *klist =
703 container_of(rcu, struct keyring_list, rcu);
704
705 if (klist->delkey != USHRT_MAX)
706 key_put(klist->keys[klist->delkey]);
707 kfree(klist);
708}
709
710/*
711 * Preallocate memory so that a key can be linked into to a keyring.
712 */
713int __key_link_begin(struct key *keyring, const struct key_type *type,
714 const char *description, unsigned long *_prealloc)
715 __acquires(&keyring->sem)
716{
717 struct keyring_list *klist, *nklist;
718 unsigned long prealloc;
719 unsigned max;
720 size_t size;
721 int loop, ret;
722
723 kenter("%d,%s,%s,", key_serial(keyring), type->name, description);
724
725 if (keyring->type != &key_type_keyring)
726 return -ENOTDIR;
727
728 down_write(&keyring->sem);
729
730 ret = -EKEYREVOKED;
731 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
732 goto error_krsem;
733
734 /* serialise link/link calls to prevent parallel calls causing a cycle
735 * when linking two keyring in opposite orders */
736 if (type == &key_type_keyring)
737 down_write(&keyring_serialise_link_sem);
738
739 klist = rcu_dereference_locked_keyring(keyring);
740
741 /* see if there's a matching key we can displace */
742 if (klist && klist->nkeys > 0) {
743 for (loop = klist->nkeys - 1; loop >= 0; loop--) {
744 if (klist->keys[loop]->type == type &&
745 strcmp(klist->keys[loop]->description,
746 description) == 0
747 ) {
748 /* found a match - we'll replace this one with
749 * the new key */
750 size = sizeof(struct key *) * klist->maxkeys;
751 size += sizeof(*klist);
752 BUG_ON(size > PAGE_SIZE);
753
754 ret = -ENOMEM;
755 nklist = kmemdup(klist, size, GFP_KERNEL);
756 if (!nklist)
757 goto error_sem;
758
759 /* note replacement slot */
760 klist->delkey = nklist->delkey = loop;
761 prealloc = (unsigned long)nklist;
762 goto done;
763 }
764 }
765 }
766
767 /* check that we aren't going to overrun the user's quota */
768 ret = key_payload_reserve(keyring,
769 keyring->datalen + KEYQUOTA_LINK_BYTES);
770 if (ret < 0)
771 goto error_sem;
772
773 if (klist && klist->nkeys < klist->maxkeys) {
774 /* there's sufficient slack space to append directly */
775 nklist = NULL;
776 prealloc = KEY_LINK_FIXQUOTA;
777 } else {
778 /* grow the key list */
779 max = 4;
780 if (klist)
781 max += klist->maxkeys;
782
783 ret = -ENFILE;
784 if (max > USHRT_MAX - 1)
785 goto error_quota;
786 size = sizeof(*klist) + sizeof(struct key *) * max;
787 if (size > PAGE_SIZE)
788 goto error_quota;
789
790 ret = -ENOMEM;
791 nklist = kmalloc(size, GFP_KERNEL);
792 if (!nklist)
793 goto error_quota;
794
795 nklist->maxkeys = max;
796 if (klist) {
797 memcpy(nklist->keys, klist->keys,
798 sizeof(struct key *) * klist->nkeys);
799 nklist->delkey = klist->nkeys;
800 nklist->nkeys = klist->nkeys + 1;
801 klist->delkey = USHRT_MAX;
802 } else {
803 nklist->nkeys = 1;
804 nklist->delkey = 0;
805 }
806
807 /* add the key into the new space */
808 nklist->keys[nklist->delkey] = NULL;
809 }
810
811 prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA;
812done:
813 *_prealloc = prealloc;
814 kleave(" = 0");
815 return 0;
816
817error_quota:
818 /* undo the quota changes */
819 key_payload_reserve(keyring,
820 keyring->datalen - KEYQUOTA_LINK_BYTES);
821error_sem:
822 if (type == &key_type_keyring)
823 up_write(&keyring_serialise_link_sem);
824error_krsem:
825 up_write(&keyring->sem);
826 kleave(" = %d", ret);
827 return ret;
828}
829
830/*
831 * Check already instantiated keys aren't going to be a problem.
832 *
833 * The caller must have called __key_link_begin(). Don't need to call this for
834 * keys that were created since __key_link_begin() was called.
835 */
836int __key_link_check_live_key(struct key *keyring, struct key *key)
837{
838 if (key->type == &key_type_keyring)
839 /* check that we aren't going to create a cycle by linking one
840 * keyring to another */
841 return keyring_detect_cycle(keyring, key);
842 return 0;
843}
844
845/*
846 * Link a key into to a keyring.
847 *
848 * Must be called with __key_link_begin() having being called. Discards any
849 * already extant link to matching key if there is one, so that each keyring
850 * holds at most one link to any given key of a particular type+description
851 * combination.
852 */
853void __key_link(struct key *keyring, struct key *key,
854 unsigned long *_prealloc)
855{
856 struct keyring_list *klist, *nklist;
857
858 nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA);
859 *_prealloc = 0;
860
861 kenter("%d,%d,%p", keyring->serial, key->serial, nklist);
862
863 klist = rcu_dereference_protected(keyring->payload.subscriptions,
864 rwsem_is_locked(&keyring->sem));
865
866 atomic_inc(&key->usage);
867
868 /* there's a matching key we can displace or an empty slot in a newly
869 * allocated list we can fill */
870 if (nklist) {
871 kdebug("replace %hu/%hu/%hu",
872 nklist->delkey, nklist->nkeys, nklist->maxkeys);
873
874 nklist->keys[nklist->delkey] = key;
875
876 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
877
878 /* dispose of the old keyring list and, if there was one, the
879 * displaced key */
880 if (klist) {
881 kdebug("dispose %hu/%hu/%hu",
882 klist->delkey, klist->nkeys, klist->maxkeys);
883 call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
884 }
885 } else {
886 /* there's sufficient slack space to append directly */
887 klist->keys[klist->nkeys] = key;
888 smp_wmb();
889 klist->nkeys++;
890 }
891}
892
893/*
894 * Finish linking a key into to a keyring.
895 *
896 * Must be called with __key_link_begin() having being called.
897 */
898void __key_link_end(struct key *keyring, struct key_type *type,
899 unsigned long prealloc)
900 __releases(&keyring->sem)
901{
902 BUG_ON(type == NULL);
903 BUG_ON(type->name == NULL);
904 kenter("%d,%s,%lx", keyring->serial, type->name, prealloc);
905
906 if (type == &key_type_keyring)
907 up_write(&keyring_serialise_link_sem);
908
909 if (prealloc) {
910 if (prealloc & KEY_LINK_FIXQUOTA)
911 key_payload_reserve(keyring,
912 keyring->datalen -
913 KEYQUOTA_LINK_BYTES);
914 kfree((struct keyring_list *)(prealloc & ~KEY_LINK_FIXQUOTA));
915 }
916 up_write(&keyring->sem);
917}
918
919/**
920 * key_link - Link a key to a keyring
921 * @keyring: The keyring to make the link in.
922 * @key: The key to link to.
923 *
924 * Make a link in a keyring to a key, such that the keyring holds a reference
925 * on that key and the key can potentially be found by searching that keyring.
926 *
927 * This function will write-lock the keyring's semaphore and will consume some
928 * of the user's key data quota to hold the link.
929 *
930 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
931 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
932 * full, -EDQUOT if there is insufficient key data quota remaining to add
933 * another link or -ENOMEM if there's insufficient memory.
934 *
935 * It is assumed that the caller has checked that it is permitted for a link to
936 * be made (the keyring should have Write permission and the key Link
937 * permission).
938 */
939int key_link(struct key *keyring, struct key *key)
940{
941 unsigned long prealloc;
942 int ret;
943
944 key_check(keyring);
945 key_check(key);
946
947 ret = __key_link_begin(keyring, key->type, key->description, &prealloc);
948 if (ret == 0) {
949 ret = __key_link_check_live_key(keyring, key);
950 if (ret == 0)
951 __key_link(keyring, key, &prealloc);
952 __key_link_end(keyring, key->type, prealloc);
953 }
954
955 return ret;
956}
957EXPORT_SYMBOL(key_link);
958
959/**
960 * key_unlink - Unlink the first link to a key from a keyring.
961 * @keyring: The keyring to remove the link from.
962 * @key: The key the link is to.
963 *
964 * Remove a link from a keyring to a key.
965 *
966 * This function will write-lock the keyring's semaphore.
967 *
968 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
969 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
970 * memory.
971 *
972 * It is assumed that the caller has checked that it is permitted for a link to
973 * be removed (the keyring should have Write permission; no permissions are
974 * required on the key).
975 */
976int key_unlink(struct key *keyring, struct key *key)
977{
978 struct keyring_list *klist, *nklist;
979 int loop, ret;
980
981 key_check(keyring);
982 key_check(key);
983
984 ret = -ENOTDIR;
985 if (keyring->type != &key_type_keyring)
986 goto error;
987
988 down_write(&keyring->sem);
989
990 klist = rcu_dereference_locked_keyring(keyring);
991 if (klist) {
992 /* search the keyring for the key */
993 for (loop = 0; loop < klist->nkeys; loop++)
994 if (klist->keys[loop] == key)
995 goto key_is_present;
996 }
997
998 up_write(&keyring->sem);
999 ret = -ENOENT;
1000 goto error;
1001
1002key_is_present:
1003 /* we need to copy the key list for RCU purposes */
1004 nklist = kmalloc(sizeof(*klist) +
1005 sizeof(struct key *) * klist->maxkeys,
1006 GFP_KERNEL);
1007 if (!nklist)
1008 goto nomem;
1009 nklist->maxkeys = klist->maxkeys;
1010 nklist->nkeys = klist->nkeys - 1;
1011
1012 if (loop > 0)
1013 memcpy(&nklist->keys[0],
1014 &klist->keys[0],
1015 loop * sizeof(struct key *));
1016
1017 if (loop < nklist->nkeys)
1018 memcpy(&nklist->keys[loop],
1019 &klist->keys[loop + 1],
1020 (nklist->nkeys - loop) * sizeof(struct key *));
1021
1022 /* adjust the user's quota */
1023 key_payload_reserve(keyring,
1024 keyring->datalen - KEYQUOTA_LINK_BYTES);
1025
1026 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
1027
1028 up_write(&keyring->sem);
1029
1030 /* schedule for later cleanup */
1031 klist->delkey = loop;
1032 call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
1033
1034 ret = 0;
1035
1036error:
1037 return ret;
1038nomem:
1039 ret = -ENOMEM;
1040 up_write(&keyring->sem);
1041 goto error;
1042}
1043EXPORT_SYMBOL(key_unlink);
1044
1045/*
1046 * Dispose of a keyring list after the RCU grace period, releasing the keys it
1047 * links to.
1048 */
1049static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
1050{
1051 struct keyring_list *klist;
1052 int loop;
1053
1054 klist = container_of(rcu, struct keyring_list, rcu);
1055
1056 for (loop = klist->nkeys - 1; loop >= 0; loop--)
1057 key_put(klist->keys[loop]);
1058
1059 kfree(klist);
1060}
1061
1062/**
1063 * keyring_clear - Clear a keyring
1064 * @keyring: The keyring to clear.
1065 *
1066 * Clear the contents of the specified keyring.
1067 *
1068 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1069 */
1070int keyring_clear(struct key *keyring)
1071{
1072 struct keyring_list *klist;
1073 int ret;
1074
1075 ret = -ENOTDIR;
1076 if (keyring->type == &key_type_keyring) {
1077 /* detach the pointer block with the locks held */
1078 down_write(&keyring->sem);
1079
1080 klist = rcu_dereference_locked_keyring(keyring);
1081 if (klist) {
1082 /* adjust the quota */
1083 key_payload_reserve(keyring,
1084 sizeof(struct keyring_list));
1085
1086 rcu_assign_pointer(keyring->payload.subscriptions,
1087 NULL);
1088 }
1089
1090 up_write(&keyring->sem);
1091
1092 /* free the keys after the locks have been dropped */
1093 if (klist)
1094 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1095
1096 ret = 0;
1097 }
1098
1099 return ret;
1100}
1101EXPORT_SYMBOL(keyring_clear);
1102
1103/*
1104 * Dispose of the links from a revoked keyring.
1105 *
1106 * This is called with the key sem write-locked.
1107 */
1108static void keyring_revoke(struct key *keyring)
1109{
1110 struct keyring_list *klist;
1111
1112 klist = rcu_dereference_locked_keyring(keyring);
1113
1114 /* adjust the quota */
1115 key_payload_reserve(keyring, 0);
1116
1117 if (klist) {
1118 rcu_assign_pointer(keyring->payload.subscriptions, NULL);
1119 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1120 }
1121}
1122
1123/*
1124 * Determine whether a key is dead.
1125 */
1126static bool key_is_dead(struct key *key, time_t limit)
1127{
1128 return test_bit(KEY_FLAG_DEAD, &key->flags) ||
1129 (key->expiry > 0 && key->expiry <= limit);
1130}
1131
1132/*
1133 * Collect garbage from the contents of a keyring, replacing the old list with
1134 * a new one with the pointers all shuffled down.
1135 *
1136 * Dead keys are classed as oned that are flagged as being dead or are revoked,
1137 * expired or negative keys that were revoked or expired before the specified
1138 * limit.
1139 */
1140void keyring_gc(struct key *keyring, time_t limit)
1141{
1142 struct keyring_list *klist, *new;
1143 struct key *key;
1144 int loop, keep, max;
1145
1146 kenter("{%x,%s}", key_serial(keyring), keyring->description);
1147
1148 down_write(&keyring->sem);
1149
1150 klist = rcu_dereference_locked_keyring(keyring);
1151 if (!klist)
1152 goto no_klist;
1153
1154 /* work out how many subscriptions we're keeping */
1155 keep = 0;
1156 for (loop = klist->nkeys - 1; loop >= 0; loop--)
1157 if (!key_is_dead(klist->keys[loop], limit))
1158 keep++;
1159
1160 if (keep == klist->nkeys)
1161 goto just_return;
1162
1163 /* allocate a new keyring payload */
1164 max = roundup(keep, 4);
1165 new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *),
1166 GFP_KERNEL);
1167 if (!new)
1168 goto nomem;
1169 new->maxkeys = max;
1170 new->nkeys = 0;
1171 new->delkey = 0;
1172
1173 /* install the live keys
1174 * - must take care as expired keys may be updated back to life
1175 */
1176 keep = 0;
1177 for (loop = klist->nkeys - 1; loop >= 0; loop--) {
1178 key = klist->keys[loop];
1179 if (!key_is_dead(key, limit)) {
1180 if (keep >= max)
1181 goto discard_new;
1182 new->keys[keep++] = key_get(key);
1183 }
1184 }
1185 new->nkeys = keep;
1186
1187 /* adjust the quota */
1188 key_payload_reserve(keyring,
1189 sizeof(struct keyring_list) +
1190 KEYQUOTA_LINK_BYTES * keep);
1191
1192 if (keep == 0) {
1193 rcu_assign_pointer(keyring->payload.subscriptions, NULL);
1194 kfree(new);
1195 } else {
1196 rcu_assign_pointer(keyring->payload.subscriptions, new);
1197 }
1198
1199 up_write(&keyring->sem);
1200
1201 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1202 kleave(" [yes]");
1203 return;
1204
1205discard_new:
1206 new->nkeys = keep;
1207 keyring_clear_rcu_disposal(&new->rcu);
1208 up_write(&keyring->sem);
1209 kleave(" [discard]");
1210 return;
1211
1212just_return:
1213 up_write(&keyring->sem);
1214 kleave(" [no dead]");
1215 return;
1216
1217no_klist:
1218 up_write(&keyring->sem);
1219 kleave(" [no_klist]");
1220 return;
1221
1222nomem:
1223 up_write(&keyring->sem);
1224 kleave(" [oom]");
1225}
1/* Keyring handling
2 *
3 * Copyright (C) 2004-2005, 2008, 2013 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/module.h>
13#include <linux/init.h>
14#include <linux/sched.h>
15#include <linux/slab.h>
16#include <linux/security.h>
17#include <linux/seq_file.h>
18#include <linux/err.h>
19#include <keys/keyring-type.h>
20#include <keys/user-type.h>
21#include <linux/assoc_array_priv.h>
22#include <linux/uaccess.h>
23#include "internal.h"
24
25/*
26 * When plumbing the depths of the key tree, this sets a hard limit
27 * set on how deep we're willing to go.
28 */
29#define KEYRING_SEARCH_MAX_DEPTH 6
30
31/*
32 * We keep all named keyrings in a hash to speed looking them up.
33 */
34#define KEYRING_NAME_HASH_SIZE (1 << 5)
35
36/*
37 * We mark pointers we pass to the associative array with bit 1 set if
38 * they're keyrings and clear otherwise.
39 */
40#define KEYRING_PTR_SUBTYPE 0x2UL
41
42static inline bool keyring_ptr_is_keyring(const struct assoc_array_ptr *x)
43{
44 return (unsigned long)x & KEYRING_PTR_SUBTYPE;
45}
46static inline struct key *keyring_ptr_to_key(const struct assoc_array_ptr *x)
47{
48 void *object = assoc_array_ptr_to_leaf(x);
49 return (struct key *)((unsigned long)object & ~KEYRING_PTR_SUBTYPE);
50}
51static inline void *keyring_key_to_ptr(struct key *key)
52{
53 if (key->type == &key_type_keyring)
54 return (void *)((unsigned long)key | KEYRING_PTR_SUBTYPE);
55 return key;
56}
57
58static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE];
59static DEFINE_RWLOCK(keyring_name_lock);
60
61static inline unsigned keyring_hash(const char *desc)
62{
63 unsigned bucket = 0;
64
65 for (; *desc; desc++)
66 bucket += (unsigned char)*desc;
67
68 return bucket & (KEYRING_NAME_HASH_SIZE - 1);
69}
70
71/*
72 * The keyring key type definition. Keyrings are simply keys of this type and
73 * can be treated as ordinary keys in addition to having their own special
74 * operations.
75 */
76static int keyring_preparse(struct key_preparsed_payload *prep);
77static void keyring_free_preparse(struct key_preparsed_payload *prep);
78static int keyring_instantiate(struct key *keyring,
79 struct key_preparsed_payload *prep);
80static void keyring_revoke(struct key *keyring);
81static void keyring_destroy(struct key *keyring);
82static void keyring_describe(const struct key *keyring, struct seq_file *m);
83static long keyring_read(const struct key *keyring,
84 char __user *buffer, size_t buflen);
85
86struct key_type key_type_keyring = {
87 .name = "keyring",
88 .def_datalen = 0,
89 .preparse = keyring_preparse,
90 .free_preparse = keyring_free_preparse,
91 .instantiate = keyring_instantiate,
92 .revoke = keyring_revoke,
93 .destroy = keyring_destroy,
94 .describe = keyring_describe,
95 .read = keyring_read,
96};
97EXPORT_SYMBOL(key_type_keyring);
98
99/*
100 * Semaphore to serialise link/link calls to prevent two link calls in parallel
101 * introducing a cycle.
102 */
103static DECLARE_RWSEM(keyring_serialise_link_sem);
104
105/*
106 * Publish the name of a keyring so that it can be found by name (if it has
107 * one).
108 */
109static void keyring_publish_name(struct key *keyring)
110{
111 int bucket;
112
113 if (keyring->description) {
114 bucket = keyring_hash(keyring->description);
115
116 write_lock(&keyring_name_lock);
117
118 if (!keyring_name_hash[bucket].next)
119 INIT_LIST_HEAD(&keyring_name_hash[bucket]);
120
121 list_add_tail(&keyring->name_link,
122 &keyring_name_hash[bucket]);
123
124 write_unlock(&keyring_name_lock);
125 }
126}
127
128/*
129 * Preparse a keyring payload
130 */
131static int keyring_preparse(struct key_preparsed_payload *prep)
132{
133 return prep->datalen != 0 ? -EINVAL : 0;
134}
135
136/*
137 * Free a preparse of a user defined key payload
138 */
139static void keyring_free_preparse(struct key_preparsed_payload *prep)
140{
141}
142
143/*
144 * Initialise a keyring.
145 *
146 * Returns 0 on success, -EINVAL if given any data.
147 */
148static int keyring_instantiate(struct key *keyring,
149 struct key_preparsed_payload *prep)
150{
151 assoc_array_init(&keyring->keys);
152 /* make the keyring available by name if it has one */
153 keyring_publish_name(keyring);
154 return 0;
155}
156
157/*
158 * Multiply 64-bits by 32-bits to 96-bits and fold back to 64-bit. Ideally we'd
159 * fold the carry back too, but that requires inline asm.
160 */
161static u64 mult_64x32_and_fold(u64 x, u32 y)
162{
163 u64 hi = (u64)(u32)(x >> 32) * y;
164 u64 lo = (u64)(u32)(x) * y;
165 return lo + ((u64)(u32)hi << 32) + (u32)(hi >> 32);
166}
167
168/*
169 * Hash a key type and description.
170 */
171static unsigned long hash_key_type_and_desc(const struct keyring_index_key *index_key)
172{
173 const unsigned level_shift = ASSOC_ARRAY_LEVEL_STEP;
174 const unsigned long fan_mask = ASSOC_ARRAY_FAN_MASK;
175 const char *description = index_key->description;
176 unsigned long hash, type;
177 u32 piece;
178 u64 acc;
179 int n, desc_len = index_key->desc_len;
180
181 type = (unsigned long)index_key->type;
182
183 acc = mult_64x32_and_fold(type, desc_len + 13);
184 acc = mult_64x32_and_fold(acc, 9207);
185 for (;;) {
186 n = desc_len;
187 if (n <= 0)
188 break;
189 if (n > 4)
190 n = 4;
191 piece = 0;
192 memcpy(&piece, description, n);
193 description += n;
194 desc_len -= n;
195 acc = mult_64x32_and_fold(acc, piece);
196 acc = mult_64x32_and_fold(acc, 9207);
197 }
198
199 /* Fold the hash down to 32 bits if need be. */
200 hash = acc;
201 if (ASSOC_ARRAY_KEY_CHUNK_SIZE == 32)
202 hash ^= acc >> 32;
203
204 /* Squidge all the keyrings into a separate part of the tree to
205 * ordinary keys by making sure the lowest level segment in the hash is
206 * zero for keyrings and non-zero otherwise.
207 */
208 if (index_key->type != &key_type_keyring && (hash & fan_mask) == 0)
209 return hash | (hash >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - level_shift)) | 1;
210 if (index_key->type == &key_type_keyring && (hash & fan_mask) != 0)
211 return (hash + (hash << level_shift)) & ~fan_mask;
212 return hash;
213}
214
215/*
216 * Build the next index key chunk.
217 *
218 * On 32-bit systems the index key is laid out as:
219 *
220 * 0 4 5 9...
221 * hash desclen typeptr desc[]
222 *
223 * On 64-bit systems:
224 *
225 * 0 8 9 17...
226 * hash desclen typeptr desc[]
227 *
228 * We return it one word-sized chunk at a time.
229 */
230static unsigned long keyring_get_key_chunk(const void *data, int level)
231{
232 const struct keyring_index_key *index_key = data;
233 unsigned long chunk = 0;
234 long offset = 0;
235 int desc_len = index_key->desc_len, n = sizeof(chunk);
236
237 level /= ASSOC_ARRAY_KEY_CHUNK_SIZE;
238 switch (level) {
239 case 0:
240 return hash_key_type_and_desc(index_key);
241 case 1:
242 return ((unsigned long)index_key->type << 8) | desc_len;
243 case 2:
244 if (desc_len == 0)
245 return (u8)((unsigned long)index_key->type >>
246 (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
247 n--;
248 offset = 1;
249 default:
250 offset += sizeof(chunk) - 1;
251 offset += (level - 3) * sizeof(chunk);
252 if (offset >= desc_len)
253 return 0;
254 desc_len -= offset;
255 if (desc_len > n)
256 desc_len = n;
257 offset += desc_len;
258 do {
259 chunk <<= 8;
260 chunk |= ((u8*)index_key->description)[--offset];
261 } while (--desc_len > 0);
262
263 if (level == 2) {
264 chunk <<= 8;
265 chunk |= (u8)((unsigned long)index_key->type >>
266 (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
267 }
268 return chunk;
269 }
270}
271
272static unsigned long keyring_get_object_key_chunk(const void *object, int level)
273{
274 const struct key *key = keyring_ptr_to_key(object);
275 return keyring_get_key_chunk(&key->index_key, level);
276}
277
278static bool keyring_compare_object(const void *object, const void *data)
279{
280 const struct keyring_index_key *index_key = data;
281 const struct key *key = keyring_ptr_to_key(object);
282
283 return key->index_key.type == index_key->type &&
284 key->index_key.desc_len == index_key->desc_len &&
285 memcmp(key->index_key.description, index_key->description,
286 index_key->desc_len) == 0;
287}
288
289/*
290 * Compare the index keys of a pair of objects and determine the bit position
291 * at which they differ - if they differ.
292 */
293static int keyring_diff_objects(const void *object, const void *data)
294{
295 const struct key *key_a = keyring_ptr_to_key(object);
296 const struct keyring_index_key *a = &key_a->index_key;
297 const struct keyring_index_key *b = data;
298 unsigned long seg_a, seg_b;
299 int level, i;
300
301 level = 0;
302 seg_a = hash_key_type_and_desc(a);
303 seg_b = hash_key_type_and_desc(b);
304 if ((seg_a ^ seg_b) != 0)
305 goto differ;
306
307 /* The number of bits contributed by the hash is controlled by a
308 * constant in the assoc_array headers. Everything else thereafter we
309 * can deal with as being machine word-size dependent.
310 */
311 level += ASSOC_ARRAY_KEY_CHUNK_SIZE / 8;
312 seg_a = a->desc_len;
313 seg_b = b->desc_len;
314 if ((seg_a ^ seg_b) != 0)
315 goto differ;
316
317 /* The next bit may not work on big endian */
318 level++;
319 seg_a = (unsigned long)a->type;
320 seg_b = (unsigned long)b->type;
321 if ((seg_a ^ seg_b) != 0)
322 goto differ;
323
324 level += sizeof(unsigned long);
325 if (a->desc_len == 0)
326 goto same;
327
328 i = 0;
329 if (((unsigned long)a->description | (unsigned long)b->description) &
330 (sizeof(unsigned long) - 1)) {
331 do {
332 seg_a = *(unsigned long *)(a->description + i);
333 seg_b = *(unsigned long *)(b->description + i);
334 if ((seg_a ^ seg_b) != 0)
335 goto differ_plus_i;
336 i += sizeof(unsigned long);
337 } while (i < (a->desc_len & (sizeof(unsigned long) - 1)));
338 }
339
340 for (; i < a->desc_len; i++) {
341 seg_a = *(unsigned char *)(a->description + i);
342 seg_b = *(unsigned char *)(b->description + i);
343 if ((seg_a ^ seg_b) != 0)
344 goto differ_plus_i;
345 }
346
347same:
348 return -1;
349
350differ_plus_i:
351 level += i;
352differ:
353 i = level * 8 + __ffs(seg_a ^ seg_b);
354 return i;
355}
356
357/*
358 * Free an object after stripping the keyring flag off of the pointer.
359 */
360static void keyring_free_object(void *object)
361{
362 key_put(keyring_ptr_to_key(object));
363}
364
365/*
366 * Operations for keyring management by the index-tree routines.
367 */
368static const struct assoc_array_ops keyring_assoc_array_ops = {
369 .get_key_chunk = keyring_get_key_chunk,
370 .get_object_key_chunk = keyring_get_object_key_chunk,
371 .compare_object = keyring_compare_object,
372 .diff_objects = keyring_diff_objects,
373 .free_object = keyring_free_object,
374};
375
376/*
377 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
378 * and dispose of its data.
379 *
380 * The garbage collector detects the final key_put(), removes the keyring from
381 * the serial number tree and then does RCU synchronisation before coming here,
382 * so we shouldn't need to worry about code poking around here with the RCU
383 * readlock held by this time.
384 */
385static void keyring_destroy(struct key *keyring)
386{
387 if (keyring->description) {
388 write_lock(&keyring_name_lock);
389
390 if (keyring->name_link.next != NULL &&
391 !list_empty(&keyring->name_link))
392 list_del(&keyring->name_link);
393
394 write_unlock(&keyring_name_lock);
395 }
396
397 if (keyring->restrict_link) {
398 struct key_restriction *keyres = keyring->restrict_link;
399
400 key_put(keyres->key);
401 kfree(keyres);
402 }
403
404 assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops);
405}
406
407/*
408 * Describe a keyring for /proc.
409 */
410static void keyring_describe(const struct key *keyring, struct seq_file *m)
411{
412 if (keyring->description)
413 seq_puts(m, keyring->description);
414 else
415 seq_puts(m, "[anon]");
416
417 if (key_is_positive(keyring)) {
418 if (keyring->keys.nr_leaves_on_tree != 0)
419 seq_printf(m, ": %lu", keyring->keys.nr_leaves_on_tree);
420 else
421 seq_puts(m, ": empty");
422 }
423}
424
425struct keyring_read_iterator_context {
426 size_t buflen;
427 size_t count;
428 key_serial_t __user *buffer;
429};
430
431static int keyring_read_iterator(const void *object, void *data)
432{
433 struct keyring_read_iterator_context *ctx = data;
434 const struct key *key = keyring_ptr_to_key(object);
435 int ret;
436
437 kenter("{%s,%d},,{%zu/%zu}",
438 key->type->name, key->serial, ctx->count, ctx->buflen);
439
440 if (ctx->count >= ctx->buflen)
441 return 1;
442
443 ret = put_user(key->serial, ctx->buffer);
444 if (ret < 0)
445 return ret;
446 ctx->buffer++;
447 ctx->count += sizeof(key->serial);
448 return 0;
449}
450
451/*
452 * Read a list of key IDs from the keyring's contents in binary form
453 *
454 * The keyring's semaphore is read-locked by the caller. This prevents someone
455 * from modifying it under us - which could cause us to read key IDs multiple
456 * times.
457 */
458static long keyring_read(const struct key *keyring,
459 char __user *buffer, size_t buflen)
460{
461 struct keyring_read_iterator_context ctx;
462 long ret;
463
464 kenter("{%d},,%zu", key_serial(keyring), buflen);
465
466 if (buflen & (sizeof(key_serial_t) - 1))
467 return -EINVAL;
468
469 /* Copy as many key IDs as fit into the buffer */
470 if (buffer && buflen) {
471 ctx.buffer = (key_serial_t __user *)buffer;
472 ctx.buflen = buflen;
473 ctx.count = 0;
474 ret = assoc_array_iterate(&keyring->keys,
475 keyring_read_iterator, &ctx);
476 if (ret < 0) {
477 kleave(" = %ld [iterate]", ret);
478 return ret;
479 }
480 }
481
482 /* Return the size of the buffer needed */
483 ret = keyring->keys.nr_leaves_on_tree * sizeof(key_serial_t);
484 if (ret <= buflen)
485 kleave("= %ld [ok]", ret);
486 else
487 kleave("= %ld [buffer too small]", ret);
488 return ret;
489}
490
491/*
492 * Allocate a keyring and link into the destination keyring.
493 */
494struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
495 const struct cred *cred, key_perm_t perm,
496 unsigned long flags,
497 struct key_restriction *restrict_link,
498 struct key *dest)
499{
500 struct key *keyring;
501 int ret;
502
503 keyring = key_alloc(&key_type_keyring, description,
504 uid, gid, cred, perm, flags, restrict_link);
505 if (!IS_ERR(keyring)) {
506 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
507 if (ret < 0) {
508 key_put(keyring);
509 keyring = ERR_PTR(ret);
510 }
511 }
512
513 return keyring;
514}
515EXPORT_SYMBOL(keyring_alloc);
516
517/**
518 * restrict_link_reject - Give -EPERM to restrict link
519 * @keyring: The keyring being added to.
520 * @type: The type of key being added.
521 * @payload: The payload of the key intended to be added.
522 * @data: Additional data for evaluating restriction.
523 *
524 * Reject the addition of any links to a keyring. It can be overridden by
525 * passing KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when
526 * adding a key to a keyring.
527 *
528 * This is meant to be stored in a key_restriction structure which is passed
529 * in the restrict_link parameter to keyring_alloc().
530 */
531int restrict_link_reject(struct key *keyring,
532 const struct key_type *type,
533 const union key_payload *payload,
534 struct key *restriction_key)
535{
536 return -EPERM;
537}
538
539/*
540 * By default, we keys found by getting an exact match on their descriptions.
541 */
542bool key_default_cmp(const struct key *key,
543 const struct key_match_data *match_data)
544{
545 return strcmp(key->description, match_data->raw_data) == 0;
546}
547
548/*
549 * Iteration function to consider each key found.
550 */
551static int keyring_search_iterator(const void *object, void *iterator_data)
552{
553 struct keyring_search_context *ctx = iterator_data;
554 const struct key *key = keyring_ptr_to_key(object);
555 unsigned long kflags = READ_ONCE(key->flags);
556 short state = READ_ONCE(key->state);
557
558 kenter("{%d}", key->serial);
559
560 /* ignore keys not of this type */
561 if (key->type != ctx->index_key.type) {
562 kleave(" = 0 [!type]");
563 return 0;
564 }
565
566 /* skip invalidated, revoked and expired keys */
567 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
568 time64_t expiry = READ_ONCE(key->expiry);
569
570 if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
571 (1 << KEY_FLAG_REVOKED))) {
572 ctx->result = ERR_PTR(-EKEYREVOKED);
573 kleave(" = %d [invrev]", ctx->skipped_ret);
574 goto skipped;
575 }
576
577 if (expiry && ctx->now >= expiry) {
578 if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
579 ctx->result = ERR_PTR(-EKEYEXPIRED);
580 kleave(" = %d [expire]", ctx->skipped_ret);
581 goto skipped;
582 }
583 }
584
585 /* keys that don't match */
586 if (!ctx->match_data.cmp(key, &ctx->match_data)) {
587 kleave(" = 0 [!match]");
588 return 0;
589 }
590
591 /* key must have search permissions */
592 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
593 key_task_permission(make_key_ref(key, ctx->possessed),
594 ctx->cred, KEY_NEED_SEARCH) < 0) {
595 ctx->result = ERR_PTR(-EACCES);
596 kleave(" = %d [!perm]", ctx->skipped_ret);
597 goto skipped;
598 }
599
600 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
601 /* we set a different error code if we pass a negative key */
602 if (state < 0) {
603 ctx->result = ERR_PTR(state);
604 kleave(" = %d [neg]", ctx->skipped_ret);
605 goto skipped;
606 }
607 }
608
609 /* Found */
610 ctx->result = make_key_ref(key, ctx->possessed);
611 kleave(" = 1 [found]");
612 return 1;
613
614skipped:
615 return ctx->skipped_ret;
616}
617
618/*
619 * Search inside a keyring for a key. We can search by walking to it
620 * directly based on its index-key or we can iterate over the entire
621 * tree looking for it, based on the match function.
622 */
623static int search_keyring(struct key *keyring, struct keyring_search_context *ctx)
624{
625 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_DIRECT) {
626 const void *object;
627
628 object = assoc_array_find(&keyring->keys,
629 &keyring_assoc_array_ops,
630 &ctx->index_key);
631 return object ? ctx->iterator(object, ctx) : 0;
632 }
633 return assoc_array_iterate(&keyring->keys, ctx->iterator, ctx);
634}
635
636/*
637 * Search a tree of keyrings that point to other keyrings up to the maximum
638 * depth.
639 */
640static bool search_nested_keyrings(struct key *keyring,
641 struct keyring_search_context *ctx)
642{
643 struct {
644 struct key *keyring;
645 struct assoc_array_node *node;
646 int slot;
647 } stack[KEYRING_SEARCH_MAX_DEPTH];
648
649 struct assoc_array_shortcut *shortcut;
650 struct assoc_array_node *node;
651 struct assoc_array_ptr *ptr;
652 struct key *key;
653 int sp = 0, slot;
654
655 kenter("{%d},{%s,%s}",
656 keyring->serial,
657 ctx->index_key.type->name,
658 ctx->index_key.description);
659
660#define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK)
661 BUG_ON((ctx->flags & STATE_CHECKS) == 0 ||
662 (ctx->flags & STATE_CHECKS) == STATE_CHECKS);
663
664 if (ctx->index_key.description)
665 ctx->index_key.desc_len = strlen(ctx->index_key.description);
666
667 /* Check to see if this top-level keyring is what we are looking for
668 * and whether it is valid or not.
669 */
670 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE ||
671 keyring_compare_object(keyring, &ctx->index_key)) {
672 ctx->skipped_ret = 2;
673 switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) {
674 case 1:
675 goto found;
676 case 2:
677 return false;
678 default:
679 break;
680 }
681 }
682
683 ctx->skipped_ret = 0;
684
685 /* Start processing a new keyring */
686descend_to_keyring:
687 kdebug("descend to %d", keyring->serial);
688 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
689 (1 << KEY_FLAG_REVOKED)))
690 goto not_this_keyring;
691
692 /* Search through the keys in this keyring before its searching its
693 * subtrees.
694 */
695 if (search_keyring(keyring, ctx))
696 goto found;
697
698 /* Then manually iterate through the keyrings nested in this one.
699 *
700 * Start from the root node of the index tree. Because of the way the
701 * hash function has been set up, keyrings cluster on the leftmost
702 * branch of the root node (root slot 0) or in the root node itself.
703 * Non-keyrings avoid the leftmost branch of the root entirely (root
704 * slots 1-15).
705 */
706 ptr = READ_ONCE(keyring->keys.root);
707 if (!ptr)
708 goto not_this_keyring;
709
710 if (assoc_array_ptr_is_shortcut(ptr)) {
711 /* If the root is a shortcut, either the keyring only contains
712 * keyring pointers (everything clusters behind root slot 0) or
713 * doesn't contain any keyring pointers.
714 */
715 shortcut = assoc_array_ptr_to_shortcut(ptr);
716 if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
717 goto not_this_keyring;
718
719 ptr = READ_ONCE(shortcut->next_node);
720 node = assoc_array_ptr_to_node(ptr);
721 goto begin_node;
722 }
723
724 node = assoc_array_ptr_to_node(ptr);
725 ptr = node->slots[0];
726 if (!assoc_array_ptr_is_meta(ptr))
727 goto begin_node;
728
729descend_to_node:
730 /* Descend to a more distal node in this keyring's content tree and go
731 * through that.
732 */
733 kdebug("descend");
734 if (assoc_array_ptr_is_shortcut(ptr)) {
735 shortcut = assoc_array_ptr_to_shortcut(ptr);
736 ptr = READ_ONCE(shortcut->next_node);
737 BUG_ON(!assoc_array_ptr_is_node(ptr));
738 }
739 node = assoc_array_ptr_to_node(ptr);
740
741begin_node:
742 kdebug("begin_node");
743 slot = 0;
744ascend_to_node:
745 /* Go through the slots in a node */
746 for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
747 ptr = READ_ONCE(node->slots[slot]);
748
749 if (assoc_array_ptr_is_meta(ptr) && node->back_pointer)
750 goto descend_to_node;
751
752 if (!keyring_ptr_is_keyring(ptr))
753 continue;
754
755 key = keyring_ptr_to_key(ptr);
756
757 if (sp >= KEYRING_SEARCH_MAX_DEPTH) {
758 if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) {
759 ctx->result = ERR_PTR(-ELOOP);
760 return false;
761 }
762 goto not_this_keyring;
763 }
764
765 /* Search a nested keyring */
766 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
767 key_task_permission(make_key_ref(key, ctx->possessed),
768 ctx->cred, KEY_NEED_SEARCH) < 0)
769 continue;
770
771 /* stack the current position */
772 stack[sp].keyring = keyring;
773 stack[sp].node = node;
774 stack[sp].slot = slot;
775 sp++;
776
777 /* begin again with the new keyring */
778 keyring = key;
779 goto descend_to_keyring;
780 }
781
782 /* We've dealt with all the slots in the current node, so now we need
783 * to ascend to the parent and continue processing there.
784 */
785 ptr = READ_ONCE(node->back_pointer);
786 slot = node->parent_slot;
787
788 if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
789 shortcut = assoc_array_ptr_to_shortcut(ptr);
790 ptr = READ_ONCE(shortcut->back_pointer);
791 slot = shortcut->parent_slot;
792 }
793 if (!ptr)
794 goto not_this_keyring;
795 node = assoc_array_ptr_to_node(ptr);
796 slot++;
797
798 /* If we've ascended to the root (zero backpointer), we must have just
799 * finished processing the leftmost branch rather than the root slots -
800 * so there can't be any more keyrings for us to find.
801 */
802 if (node->back_pointer) {
803 kdebug("ascend %d", slot);
804 goto ascend_to_node;
805 }
806
807 /* The keyring we're looking at was disqualified or didn't contain a
808 * matching key.
809 */
810not_this_keyring:
811 kdebug("not_this_keyring %d", sp);
812 if (sp <= 0) {
813 kleave(" = false");
814 return false;
815 }
816
817 /* Resume the processing of a keyring higher up in the tree */
818 sp--;
819 keyring = stack[sp].keyring;
820 node = stack[sp].node;
821 slot = stack[sp].slot + 1;
822 kdebug("ascend to %d [%d]", keyring->serial, slot);
823 goto ascend_to_node;
824
825 /* We found a viable match */
826found:
827 key = key_ref_to_ptr(ctx->result);
828 key_check(key);
829 if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) {
830 key->last_used_at = ctx->now;
831 keyring->last_used_at = ctx->now;
832 while (sp > 0)
833 stack[--sp].keyring->last_used_at = ctx->now;
834 }
835 kleave(" = true");
836 return true;
837}
838
839/**
840 * keyring_search_aux - Search a keyring tree for a key matching some criteria
841 * @keyring_ref: A pointer to the keyring with possession indicator.
842 * @ctx: The keyring search context.
843 *
844 * Search the supplied keyring tree for a key that matches the criteria given.
845 * The root keyring and any linked keyrings must grant Search permission to the
846 * caller to be searchable and keys can only be found if they too grant Search
847 * to the caller. The possession flag on the root keyring pointer controls use
848 * of the possessor bits in permissions checking of the entire tree. In
849 * addition, the LSM gets to forbid keyring searches and key matches.
850 *
851 * The search is performed as a breadth-then-depth search up to the prescribed
852 * limit (KEYRING_SEARCH_MAX_DEPTH).
853 *
854 * Keys are matched to the type provided and are then filtered by the match
855 * function, which is given the description to use in any way it sees fit. The
856 * match function may use any attributes of a key that it wishes to to
857 * determine the match. Normally the match function from the key type would be
858 * used.
859 *
860 * RCU can be used to prevent the keyring key lists from disappearing without
861 * the need to take lots of locks.
862 *
863 * Returns a pointer to the found key and increments the key usage count if
864 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
865 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
866 * specified keyring wasn't a keyring.
867 *
868 * In the case of a successful return, the possession attribute from
869 * @keyring_ref is propagated to the returned key reference.
870 */
871key_ref_t keyring_search_aux(key_ref_t keyring_ref,
872 struct keyring_search_context *ctx)
873{
874 struct key *keyring;
875 long err;
876
877 ctx->iterator = keyring_search_iterator;
878 ctx->possessed = is_key_possessed(keyring_ref);
879 ctx->result = ERR_PTR(-EAGAIN);
880
881 keyring = key_ref_to_ptr(keyring_ref);
882 key_check(keyring);
883
884 if (keyring->type != &key_type_keyring)
885 return ERR_PTR(-ENOTDIR);
886
887 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) {
888 err = key_task_permission(keyring_ref, ctx->cred, KEY_NEED_SEARCH);
889 if (err < 0)
890 return ERR_PTR(err);
891 }
892
893 rcu_read_lock();
894 ctx->now = ktime_get_real_seconds();
895 if (search_nested_keyrings(keyring, ctx))
896 __key_get(key_ref_to_ptr(ctx->result));
897 rcu_read_unlock();
898 return ctx->result;
899}
900
901/**
902 * keyring_search - Search the supplied keyring tree for a matching key
903 * @keyring: The root of the keyring tree to be searched.
904 * @type: The type of keyring we want to find.
905 * @description: The name of the keyring we want to find.
906 *
907 * As keyring_search_aux() above, but using the current task's credentials and
908 * type's default matching function and preferred search method.
909 */
910key_ref_t keyring_search(key_ref_t keyring,
911 struct key_type *type,
912 const char *description)
913{
914 struct keyring_search_context ctx = {
915 .index_key.type = type,
916 .index_key.description = description,
917 .cred = current_cred(),
918 .match_data.cmp = key_default_cmp,
919 .match_data.raw_data = description,
920 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
921 .flags = KEYRING_SEARCH_DO_STATE_CHECK,
922 };
923 key_ref_t key;
924 int ret;
925
926 if (type->match_preparse) {
927 ret = type->match_preparse(&ctx.match_data);
928 if (ret < 0)
929 return ERR_PTR(ret);
930 }
931
932 key = keyring_search_aux(keyring, &ctx);
933
934 if (type->match_free)
935 type->match_free(&ctx.match_data);
936 return key;
937}
938EXPORT_SYMBOL(keyring_search);
939
940static struct key_restriction *keyring_restriction_alloc(
941 key_restrict_link_func_t check)
942{
943 struct key_restriction *keyres =
944 kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
945
946 if (!keyres)
947 return ERR_PTR(-ENOMEM);
948
949 keyres->check = check;
950
951 return keyres;
952}
953
954/*
955 * Semaphore to serialise restriction setup to prevent reference count
956 * cycles through restriction key pointers.
957 */
958static DECLARE_RWSEM(keyring_serialise_restrict_sem);
959
960/*
961 * Check for restriction cycles that would prevent keyring garbage collection.
962 * keyring_serialise_restrict_sem must be held.
963 */
964static bool keyring_detect_restriction_cycle(const struct key *dest_keyring,
965 struct key_restriction *keyres)
966{
967 while (keyres && keyres->key &&
968 keyres->key->type == &key_type_keyring) {
969 if (keyres->key == dest_keyring)
970 return true;
971
972 keyres = keyres->key->restrict_link;
973 }
974
975 return false;
976}
977
978/**
979 * keyring_restrict - Look up and apply a restriction to a keyring
980 *
981 * @keyring: The keyring to be restricted
982 * @restriction: The restriction options to apply to the keyring
983 */
984int keyring_restrict(key_ref_t keyring_ref, const char *type,
985 const char *restriction)
986{
987 struct key *keyring;
988 struct key_type *restrict_type = NULL;
989 struct key_restriction *restrict_link;
990 int ret = 0;
991
992 keyring = key_ref_to_ptr(keyring_ref);
993 key_check(keyring);
994
995 if (keyring->type != &key_type_keyring)
996 return -ENOTDIR;
997
998 if (!type) {
999 restrict_link = keyring_restriction_alloc(restrict_link_reject);
1000 } else {
1001 restrict_type = key_type_lookup(type);
1002
1003 if (IS_ERR(restrict_type))
1004 return PTR_ERR(restrict_type);
1005
1006 if (!restrict_type->lookup_restriction) {
1007 ret = -ENOENT;
1008 goto error;
1009 }
1010
1011 restrict_link = restrict_type->lookup_restriction(restriction);
1012 }
1013
1014 if (IS_ERR(restrict_link)) {
1015 ret = PTR_ERR(restrict_link);
1016 goto error;
1017 }
1018
1019 down_write(&keyring->sem);
1020 down_write(&keyring_serialise_restrict_sem);
1021
1022 if (keyring->restrict_link)
1023 ret = -EEXIST;
1024 else if (keyring_detect_restriction_cycle(keyring, restrict_link))
1025 ret = -EDEADLK;
1026 else
1027 keyring->restrict_link = restrict_link;
1028
1029 up_write(&keyring_serialise_restrict_sem);
1030 up_write(&keyring->sem);
1031
1032 if (ret < 0) {
1033 key_put(restrict_link->key);
1034 kfree(restrict_link);
1035 }
1036
1037error:
1038 if (restrict_type)
1039 key_type_put(restrict_type);
1040
1041 return ret;
1042}
1043EXPORT_SYMBOL(keyring_restrict);
1044
1045/*
1046 * Search the given keyring for a key that might be updated.
1047 *
1048 * The caller must guarantee that the keyring is a keyring and that the
1049 * permission is granted to modify the keyring as no check is made here. The
1050 * caller must also hold a lock on the keyring semaphore.
1051 *
1052 * Returns a pointer to the found key with usage count incremented if
1053 * successful and returns NULL if not found. Revoked and invalidated keys are
1054 * skipped over.
1055 *
1056 * If successful, the possession indicator is propagated from the keyring ref
1057 * to the returned key reference.
1058 */
1059key_ref_t find_key_to_update(key_ref_t keyring_ref,
1060 const struct keyring_index_key *index_key)
1061{
1062 struct key *keyring, *key;
1063 const void *object;
1064
1065 keyring = key_ref_to_ptr(keyring_ref);
1066
1067 kenter("{%d},{%s,%s}",
1068 keyring->serial, index_key->type->name, index_key->description);
1069
1070 object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops,
1071 index_key);
1072
1073 if (object)
1074 goto found;
1075
1076 kleave(" = NULL");
1077 return NULL;
1078
1079found:
1080 key = keyring_ptr_to_key(object);
1081 if (key->flags & ((1 << KEY_FLAG_INVALIDATED) |
1082 (1 << KEY_FLAG_REVOKED))) {
1083 kleave(" = NULL [x]");
1084 return NULL;
1085 }
1086 __key_get(key);
1087 kleave(" = {%d}", key->serial);
1088 return make_key_ref(key, is_key_possessed(keyring_ref));
1089}
1090
1091/*
1092 * Find a keyring with the specified name.
1093 *
1094 * Only keyrings that have nonzero refcount, are not revoked, and are owned by a
1095 * user in the current user namespace are considered. If @uid_keyring is %true,
1096 * the keyring additionally must have been allocated as a user or user session
1097 * keyring; otherwise, it must grant Search permission directly to the caller.
1098 *
1099 * Returns a pointer to the keyring with the keyring's refcount having being
1100 * incremented on success. -ENOKEY is returned if a key could not be found.
1101 */
1102struct key *find_keyring_by_name(const char *name, bool uid_keyring)
1103{
1104 struct key *keyring;
1105 int bucket;
1106
1107 if (!name)
1108 return ERR_PTR(-EINVAL);
1109
1110 bucket = keyring_hash(name);
1111
1112 read_lock(&keyring_name_lock);
1113
1114 if (keyring_name_hash[bucket].next) {
1115 /* search this hash bucket for a keyring with a matching name
1116 * that's readable and that hasn't been revoked */
1117 list_for_each_entry(keyring,
1118 &keyring_name_hash[bucket],
1119 name_link
1120 ) {
1121 if (!kuid_has_mapping(current_user_ns(), keyring->user->uid))
1122 continue;
1123
1124 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1125 continue;
1126
1127 if (strcmp(keyring->description, name) != 0)
1128 continue;
1129
1130 if (uid_keyring) {
1131 if (!test_bit(KEY_FLAG_UID_KEYRING,
1132 &keyring->flags))
1133 continue;
1134 } else {
1135 if (key_permission(make_key_ref(keyring, 0),
1136 KEY_NEED_SEARCH) < 0)
1137 continue;
1138 }
1139
1140 /* we've got a match but we might end up racing with
1141 * key_cleanup() if the keyring is currently 'dead'
1142 * (ie. it has a zero usage count) */
1143 if (!refcount_inc_not_zero(&keyring->usage))
1144 continue;
1145 keyring->last_used_at = ktime_get_real_seconds();
1146 goto out;
1147 }
1148 }
1149
1150 keyring = ERR_PTR(-ENOKEY);
1151out:
1152 read_unlock(&keyring_name_lock);
1153 return keyring;
1154}
1155
1156static int keyring_detect_cycle_iterator(const void *object,
1157 void *iterator_data)
1158{
1159 struct keyring_search_context *ctx = iterator_data;
1160 const struct key *key = keyring_ptr_to_key(object);
1161
1162 kenter("{%d}", key->serial);
1163
1164 /* We might get a keyring with matching index-key that is nonetheless a
1165 * different keyring. */
1166 if (key != ctx->match_data.raw_data)
1167 return 0;
1168
1169 ctx->result = ERR_PTR(-EDEADLK);
1170 return 1;
1171}
1172
1173/*
1174 * See if a cycle will will be created by inserting acyclic tree B in acyclic
1175 * tree A at the topmost level (ie: as a direct child of A).
1176 *
1177 * Since we are adding B to A at the top level, checking for cycles should just
1178 * be a matter of seeing if node A is somewhere in tree B.
1179 */
1180static int keyring_detect_cycle(struct key *A, struct key *B)
1181{
1182 struct keyring_search_context ctx = {
1183 .index_key = A->index_key,
1184 .match_data.raw_data = A,
1185 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
1186 .iterator = keyring_detect_cycle_iterator,
1187 .flags = (KEYRING_SEARCH_NO_STATE_CHECK |
1188 KEYRING_SEARCH_NO_UPDATE_TIME |
1189 KEYRING_SEARCH_NO_CHECK_PERM |
1190 KEYRING_SEARCH_DETECT_TOO_DEEP),
1191 };
1192
1193 rcu_read_lock();
1194 search_nested_keyrings(B, &ctx);
1195 rcu_read_unlock();
1196 return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);
1197}
1198
1199/*
1200 * Preallocate memory so that a key can be linked into to a keyring.
1201 */
1202int __key_link_begin(struct key *keyring,
1203 const struct keyring_index_key *index_key,
1204 struct assoc_array_edit **_edit)
1205 __acquires(&keyring->sem)
1206 __acquires(&keyring_serialise_link_sem)
1207{
1208 struct assoc_array_edit *edit;
1209 int ret;
1210
1211 kenter("%d,%s,%s,",
1212 keyring->serial, index_key->type->name, index_key->description);
1213
1214 BUG_ON(index_key->desc_len == 0);
1215
1216 if (keyring->type != &key_type_keyring)
1217 return -ENOTDIR;
1218
1219 down_write(&keyring->sem);
1220
1221 ret = -EKEYREVOKED;
1222 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1223 goto error_krsem;
1224
1225 /* serialise link/link calls to prevent parallel calls causing a cycle
1226 * when linking two keyring in opposite orders */
1227 if (index_key->type == &key_type_keyring)
1228 down_write(&keyring_serialise_link_sem);
1229
1230 /* Create an edit script that will insert/replace the key in the
1231 * keyring tree.
1232 */
1233 edit = assoc_array_insert(&keyring->keys,
1234 &keyring_assoc_array_ops,
1235 index_key,
1236 NULL);
1237 if (IS_ERR(edit)) {
1238 ret = PTR_ERR(edit);
1239 goto error_sem;
1240 }
1241
1242 /* If we're not replacing a link in-place then we're going to need some
1243 * extra quota.
1244 */
1245 if (!edit->dead_leaf) {
1246 ret = key_payload_reserve(keyring,
1247 keyring->datalen + KEYQUOTA_LINK_BYTES);
1248 if (ret < 0)
1249 goto error_cancel;
1250 }
1251
1252 *_edit = edit;
1253 kleave(" = 0");
1254 return 0;
1255
1256error_cancel:
1257 assoc_array_cancel_edit(edit);
1258error_sem:
1259 if (index_key->type == &key_type_keyring)
1260 up_write(&keyring_serialise_link_sem);
1261error_krsem:
1262 up_write(&keyring->sem);
1263 kleave(" = %d", ret);
1264 return ret;
1265}
1266
1267/*
1268 * Check already instantiated keys aren't going to be a problem.
1269 *
1270 * The caller must have called __key_link_begin(). Don't need to call this for
1271 * keys that were created since __key_link_begin() was called.
1272 */
1273int __key_link_check_live_key(struct key *keyring, struct key *key)
1274{
1275 if (key->type == &key_type_keyring)
1276 /* check that we aren't going to create a cycle by linking one
1277 * keyring to another */
1278 return keyring_detect_cycle(keyring, key);
1279 return 0;
1280}
1281
1282/*
1283 * Link a key into to a keyring.
1284 *
1285 * Must be called with __key_link_begin() having being called. Discards any
1286 * already extant link to matching key if there is one, so that each keyring
1287 * holds at most one link to any given key of a particular type+description
1288 * combination.
1289 */
1290void __key_link(struct key *key, struct assoc_array_edit **_edit)
1291{
1292 __key_get(key);
1293 assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key));
1294 assoc_array_apply_edit(*_edit);
1295 *_edit = NULL;
1296}
1297
1298/*
1299 * Finish linking a key into to a keyring.
1300 *
1301 * Must be called with __key_link_begin() having being called.
1302 */
1303void __key_link_end(struct key *keyring,
1304 const struct keyring_index_key *index_key,
1305 struct assoc_array_edit *edit)
1306 __releases(&keyring->sem)
1307 __releases(&keyring_serialise_link_sem)
1308{
1309 BUG_ON(index_key->type == NULL);
1310 kenter("%d,%s,", keyring->serial, index_key->type->name);
1311
1312 if (index_key->type == &key_type_keyring)
1313 up_write(&keyring_serialise_link_sem);
1314
1315 if (edit) {
1316 if (!edit->dead_leaf) {
1317 key_payload_reserve(keyring,
1318 keyring->datalen - KEYQUOTA_LINK_BYTES);
1319 }
1320 assoc_array_cancel_edit(edit);
1321 }
1322 up_write(&keyring->sem);
1323}
1324
1325/*
1326 * Check addition of keys to restricted keyrings.
1327 */
1328static int __key_link_check_restriction(struct key *keyring, struct key *key)
1329{
1330 if (!keyring->restrict_link || !keyring->restrict_link->check)
1331 return 0;
1332 return keyring->restrict_link->check(keyring, key->type, &key->payload,
1333 keyring->restrict_link->key);
1334}
1335
1336/**
1337 * key_link - Link a key to a keyring
1338 * @keyring: The keyring to make the link in.
1339 * @key: The key to link to.
1340 *
1341 * Make a link in a keyring to a key, such that the keyring holds a reference
1342 * on that key and the key can potentially be found by searching that keyring.
1343 *
1344 * This function will write-lock the keyring's semaphore and will consume some
1345 * of the user's key data quota to hold the link.
1346 *
1347 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1348 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1349 * full, -EDQUOT if there is insufficient key data quota remaining to add
1350 * another link or -ENOMEM if there's insufficient memory.
1351 *
1352 * It is assumed that the caller has checked that it is permitted for a link to
1353 * be made (the keyring should have Write permission and the key Link
1354 * permission).
1355 */
1356int key_link(struct key *keyring, struct key *key)
1357{
1358 struct assoc_array_edit *edit;
1359 int ret;
1360
1361 kenter("{%d,%d}", keyring->serial, refcount_read(&keyring->usage));
1362
1363 key_check(keyring);
1364 key_check(key);
1365
1366 ret = __key_link_begin(keyring, &key->index_key, &edit);
1367 if (ret == 0) {
1368 kdebug("begun {%d,%d}", keyring->serial, refcount_read(&keyring->usage));
1369 ret = __key_link_check_restriction(keyring, key);
1370 if (ret == 0)
1371 ret = __key_link_check_live_key(keyring, key);
1372 if (ret == 0)
1373 __key_link(key, &edit);
1374 __key_link_end(keyring, &key->index_key, edit);
1375 }
1376
1377 kleave(" = %d {%d,%d}", ret, keyring->serial, refcount_read(&keyring->usage));
1378 return ret;
1379}
1380EXPORT_SYMBOL(key_link);
1381
1382/**
1383 * key_unlink - Unlink the first link to a key from a keyring.
1384 * @keyring: The keyring to remove the link from.
1385 * @key: The key the link is to.
1386 *
1387 * Remove a link from a keyring to a key.
1388 *
1389 * This function will write-lock the keyring's semaphore.
1390 *
1391 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1392 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1393 * memory.
1394 *
1395 * It is assumed that the caller has checked that it is permitted for a link to
1396 * be removed (the keyring should have Write permission; no permissions are
1397 * required on the key).
1398 */
1399int key_unlink(struct key *keyring, struct key *key)
1400{
1401 struct assoc_array_edit *edit;
1402 int ret;
1403
1404 key_check(keyring);
1405 key_check(key);
1406
1407 if (keyring->type != &key_type_keyring)
1408 return -ENOTDIR;
1409
1410 down_write(&keyring->sem);
1411
1412 edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
1413 &key->index_key);
1414 if (IS_ERR(edit)) {
1415 ret = PTR_ERR(edit);
1416 goto error;
1417 }
1418 ret = -ENOENT;
1419 if (edit == NULL)
1420 goto error;
1421
1422 assoc_array_apply_edit(edit);
1423 key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
1424 ret = 0;
1425
1426error:
1427 up_write(&keyring->sem);
1428 return ret;
1429}
1430EXPORT_SYMBOL(key_unlink);
1431
1432/**
1433 * keyring_clear - Clear a keyring
1434 * @keyring: The keyring to clear.
1435 *
1436 * Clear the contents of the specified keyring.
1437 *
1438 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1439 */
1440int keyring_clear(struct key *keyring)
1441{
1442 struct assoc_array_edit *edit;
1443 int ret;
1444
1445 if (keyring->type != &key_type_keyring)
1446 return -ENOTDIR;
1447
1448 down_write(&keyring->sem);
1449
1450 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1451 if (IS_ERR(edit)) {
1452 ret = PTR_ERR(edit);
1453 } else {
1454 if (edit)
1455 assoc_array_apply_edit(edit);
1456 key_payload_reserve(keyring, 0);
1457 ret = 0;
1458 }
1459
1460 up_write(&keyring->sem);
1461 return ret;
1462}
1463EXPORT_SYMBOL(keyring_clear);
1464
1465/*
1466 * Dispose of the links from a revoked keyring.
1467 *
1468 * This is called with the key sem write-locked.
1469 */
1470static void keyring_revoke(struct key *keyring)
1471{
1472 struct assoc_array_edit *edit;
1473
1474 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1475 if (!IS_ERR(edit)) {
1476 if (edit)
1477 assoc_array_apply_edit(edit);
1478 key_payload_reserve(keyring, 0);
1479 }
1480}
1481
1482static bool keyring_gc_select_iterator(void *object, void *iterator_data)
1483{
1484 struct key *key = keyring_ptr_to_key(object);
1485 time64_t *limit = iterator_data;
1486
1487 if (key_is_dead(key, *limit))
1488 return false;
1489 key_get(key);
1490 return true;
1491}
1492
1493static int keyring_gc_check_iterator(const void *object, void *iterator_data)
1494{
1495 const struct key *key = keyring_ptr_to_key(object);
1496 time64_t *limit = iterator_data;
1497
1498 key_check(key);
1499 return key_is_dead(key, *limit);
1500}
1501
1502/*
1503 * Garbage collect pointers from a keyring.
1504 *
1505 * Not called with any locks held. The keyring's key struct will not be
1506 * deallocated under us as only our caller may deallocate it.
1507 */
1508void keyring_gc(struct key *keyring, time64_t limit)
1509{
1510 int result;
1511
1512 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1513
1514 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
1515 (1 << KEY_FLAG_REVOKED)))
1516 goto dont_gc;
1517
1518 /* scan the keyring looking for dead keys */
1519 rcu_read_lock();
1520 result = assoc_array_iterate(&keyring->keys,
1521 keyring_gc_check_iterator, &limit);
1522 rcu_read_unlock();
1523 if (result == true)
1524 goto do_gc;
1525
1526dont_gc:
1527 kleave(" [no gc]");
1528 return;
1529
1530do_gc:
1531 down_write(&keyring->sem);
1532 assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops,
1533 keyring_gc_select_iterator, &limit);
1534 up_write(&keyring->sem);
1535 kleave(" [gc]");
1536}
1537
1538/*
1539 * Garbage collect restriction pointers from a keyring.
1540 *
1541 * Keyring restrictions are associated with a key type, and must be cleaned
1542 * up if the key type is unregistered. The restriction is altered to always
1543 * reject additional keys so a keyring cannot be opened up by unregistering
1544 * a key type.
1545 *
1546 * Not called with any keyring locks held. The keyring's key struct will not
1547 * be deallocated under us as only our caller may deallocate it.
1548 *
1549 * The caller is required to hold key_types_sem and dead_type->sem. This is
1550 * fulfilled by key_gc_keytype() holding the locks on behalf of
1551 * key_garbage_collector(), which it invokes on a workqueue.
1552 */
1553void keyring_restriction_gc(struct key *keyring, struct key_type *dead_type)
1554{
1555 struct key_restriction *keyres;
1556
1557 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1558
1559 /*
1560 * keyring->restrict_link is only assigned at key allocation time
1561 * or with the key type locked, so the only values that could be
1562 * concurrently assigned to keyring->restrict_link are for key
1563 * types other than dead_type. Given this, it's ok to check
1564 * the key type before acquiring keyring->sem.
1565 */
1566 if (!dead_type || !keyring->restrict_link ||
1567 keyring->restrict_link->keytype != dead_type) {
1568 kleave(" [no restriction gc]");
1569 return;
1570 }
1571
1572 /* Lock the keyring to ensure that a link is not in progress */
1573 down_write(&keyring->sem);
1574
1575 keyres = keyring->restrict_link;
1576
1577 keyres->check = restrict_link_reject;
1578
1579 key_put(keyres->key);
1580 keyres->key = NULL;
1581 keyres->keytype = NULL;
1582
1583 up_write(&keyring->sem);
1584
1585 kleave(" [restriction gc]");
1586}