3 * Copyright (C) 2004-2005, 2008 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
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>
23 #define rcu_dereference_locked_keyring(keyring) \
24 (rcu_dereference_protected( \
25 (keyring)->payload.subscriptions, \
26 rwsem_is_locked((struct rw_semaphore *)&(keyring)->sem)))
28 #define KEY_LINK_FIXQUOTA 1UL
31 * When plumbing the depths of the key tree, this sets a hard limit
32 * set on how deep we're willing to go.
34 #define KEYRING_SEARCH_MAX_DEPTH 6
37 * We keep all named keyrings in a hash to speed looking them up.
39 #define KEYRING_NAME_HASH_SIZE (1 << 5)
41 static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE];
42 static DEFINE_RWLOCK(keyring_name_lock);
44 static inline unsigned keyring_hash(const char *desc)
49 bucket += (unsigned char)*desc;
51 return bucket & (KEYRING_NAME_HASH_SIZE - 1);
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
59 static int keyring_instantiate(struct key *keyring,
60 const void *data, size_t datalen);
61 static int keyring_match(const struct key *keyring, const void *criterion);
62 static void keyring_revoke(struct key *keyring);
63 static void keyring_destroy(struct key *keyring);
64 static void keyring_describe(const struct key *keyring, struct seq_file *m);
65 static long keyring_read(const struct key *keyring,
66 char __user *buffer, size_t buflen);
68 struct key_type key_type_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,
78 EXPORT_SYMBOL(key_type_keyring);
81 * Semaphore to serialise link/link calls to prevent two link calls in parallel
82 * introducing a cycle.
84 static DECLARE_RWSEM(keyring_serialise_link_sem);
87 * Publish the name of a keyring so that it can be found by name (if it has
90 static void keyring_publish_name(struct key *keyring)
94 if (keyring->description) {
95 bucket = keyring_hash(keyring->description);
97 write_lock(&keyring_name_lock);
99 if (!keyring_name_hash[bucket].next)
100 INIT_LIST_HEAD(&keyring_name_hash[bucket]);
102 list_add_tail(&keyring->type_data.link,
103 &keyring_name_hash[bucket]);
105 write_unlock(&keyring_name_lock);
110 * Initialise a keyring.
112 * Returns 0 on success, -EINVAL if given any data.
114 static int keyring_instantiate(struct key *keyring,
115 const void *data, size_t datalen)
121 /* make the keyring available by name if it has one */
122 keyring_publish_name(keyring);
130 * Match keyrings on their name
132 static int keyring_match(const struct key *keyring, const void *description)
134 return keyring->description &&
135 strcmp(keyring->description, description) == 0;
139 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
140 * and dispose of its data.
142 static void keyring_destroy(struct key *keyring)
144 struct keyring_list *klist;
147 if (keyring->description) {
148 write_lock(&keyring_name_lock);
150 if (keyring->type_data.link.next != NULL &&
151 !list_empty(&keyring->type_data.link))
152 list_del(&keyring->type_data.link);
154 write_unlock(&keyring_name_lock);
157 klist = rcu_dereference_check(keyring->payload.subscriptions,
158 rcu_read_lock_held() ||
159 atomic_read(&keyring->usage) == 0);
161 for (loop = klist->nkeys - 1; loop >= 0; loop--)
162 key_put(klist->keys[loop]);
168 * Describe a keyring for /proc.
170 static void keyring_describe(const struct key *keyring, struct seq_file *m)
172 struct keyring_list *klist;
174 if (keyring->description)
175 seq_puts(m, keyring->description);
177 seq_puts(m, "[anon]");
180 klist = rcu_dereference(keyring->payload.subscriptions);
182 seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys);
184 seq_puts(m, ": empty");
189 * Read a list of key IDs from the keyring's contents in binary form
191 * The keyring's semaphore is read-locked by the caller.
193 static long keyring_read(const struct key *keyring,
194 char __user *buffer, size_t buflen)
196 struct keyring_list *klist;
202 klist = rcu_dereference_locked_keyring(keyring);
204 /* calculate how much data we could return */
205 qty = klist->nkeys * sizeof(key_serial_t);
207 if (buffer && buflen > 0) {
211 /* copy the IDs of the subscribed keys into the
215 for (loop = 0; loop < klist->nkeys; loop++) {
216 key = klist->keys[loop];
218 tmp = sizeof(key_serial_t);
222 if (copy_to_user(buffer,
242 * Allocate a keyring and link into the destination keyring.
244 struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
245 const struct cred *cred, unsigned long flags,
251 keyring = key_alloc(&key_type_keyring, description,
253 (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
256 if (!IS_ERR(keyring)) {
257 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
260 keyring = ERR_PTR(ret);
268 * keyring_search_aux - Search a keyring tree for a key matching some criteria
269 * @keyring_ref: A pointer to the keyring with possession indicator.
270 * @cred: The credentials to use for permissions checks.
271 * @type: The type of key to search for.
272 * @description: Parameter for @match.
273 * @match: Function to rule on whether or not a key is the one required.
275 * Search the supplied keyring tree for a key that matches the criteria given.
276 * The root keyring and any linked keyrings must grant Search permission to the
277 * caller to be searchable and keys can only be found if they too grant Search
278 * to the caller. The possession flag on the root keyring pointer controls use
279 * of the possessor bits in permissions checking of the entire tree. In
280 * addition, the LSM gets to forbid keyring searches and key matches.
282 * The search is performed as a breadth-then-depth search up to the prescribed
283 * limit (KEYRING_SEARCH_MAX_DEPTH).
285 * Keys are matched to the type provided and are then filtered by the match
286 * function, which is given the description to use in any way it sees fit. The
287 * match function may use any attributes of a key that it wishes to to
288 * determine the match. Normally the match function from the key type would be
291 * RCU is used to prevent the keyring key lists from disappearing without the
292 * need to take lots of locks.
294 * Returns a pointer to the found key and increments the key usage count if
295 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
296 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
297 * specified keyring wasn't a keyring.
299 * In the case of a successful return, the possession attribute from
300 * @keyring_ref is propagated to the returned key reference.
302 key_ref_t keyring_search_aux(key_ref_t keyring_ref,
303 const struct cred *cred,
304 struct key_type *type,
305 const void *description,
306 key_match_func_t match)
309 struct keyring_list *keylist;
311 } stack[KEYRING_SEARCH_MAX_DEPTH];
313 struct keyring_list *keylist;
315 unsigned long possessed, kflags;
316 struct key *keyring, *key;
321 keyring = key_ref_to_ptr(keyring_ref);
322 possessed = is_key_possessed(keyring_ref);
325 /* top keyring must have search permission to begin the search */
326 err = key_task_permission(keyring_ref, cred, KEY_SEARCH);
328 key_ref = ERR_PTR(err);
332 key_ref = ERR_PTR(-ENOTDIR);
333 if (keyring->type != &key_type_keyring)
338 now = current_kernel_time();
342 /* firstly we should check to see if this top-level keyring is what we
344 key_ref = ERR_PTR(-EAGAIN);
345 kflags = keyring->flags;
346 if (keyring->type == type && match(keyring, description)) {
349 /* check it isn't negative and hasn't expired or been
351 if (kflags & (1 << KEY_FLAG_REVOKED))
353 if (key->expiry && now.tv_sec >= key->expiry)
355 key_ref = ERR_PTR(-ENOKEY);
356 if (kflags & (1 << KEY_FLAG_NEGATIVE))
361 /* otherwise, the top keyring must not be revoked, expired, or
362 * negatively instantiated if we are to search it */
363 key_ref = ERR_PTR(-EAGAIN);
364 if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) ||
365 (keyring->expiry && now.tv_sec >= keyring->expiry))
368 /* start processing a new keyring */
370 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
371 goto not_this_keyring;
373 keylist = rcu_dereference(keyring->payload.subscriptions);
375 goto not_this_keyring;
377 /* iterate through the keys in this keyring first */
378 for (kix = 0; kix < keylist->nkeys; kix++) {
379 key = keylist->keys[kix];
382 /* ignore keys not of this type */
383 if (key->type != type)
386 /* skip revoked keys and expired keys */
387 if (kflags & (1 << KEY_FLAG_REVOKED))
390 if (key->expiry && now.tv_sec >= key->expiry)
393 /* keys that don't match */
394 if (!match(key, description))
397 /* key must have search permissions */
398 if (key_task_permission(make_key_ref(key, possessed),
399 cred, KEY_SEARCH) < 0)
402 /* we set a different error code if we pass a negative key */
403 if (kflags & (1 << KEY_FLAG_NEGATIVE)) {
411 /* search through the keyrings nested in this one */
414 for (; kix < keylist->nkeys; kix++) {
415 key = keylist->keys[kix];
416 if (key->type != &key_type_keyring)
419 /* recursively search nested keyrings
420 * - only search keyrings for which we have search permission
422 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
425 if (key_task_permission(make_key_ref(key, possessed),
426 cred, KEY_SEARCH) < 0)
429 /* stack the current position */
430 stack[sp].keylist = keylist;
434 /* begin again with the new keyring */
439 /* the keyring we're looking at was disqualified or didn't contain a
443 /* resume the processing of a keyring higher up in the tree */
445 keylist = stack[sp].keylist;
446 kix = stack[sp].kix + 1;
450 key_ref = ERR_PTR(err);
453 /* we found a viable match */
455 atomic_inc(&key->usage);
457 key_ref = make_key_ref(key, possessed);
465 * keyring_search - Search the supplied keyring tree for a matching key
466 * @keyring: The root of the keyring tree to be searched.
467 * @type: The type of keyring we want to find.
468 * @description: The name of the keyring we want to find.
470 * As keyring_search_aux() above, but using the current task's credentials and
471 * type's default matching function.
473 key_ref_t keyring_search(key_ref_t keyring,
474 struct key_type *type,
475 const char *description)
478 return ERR_PTR(-ENOKEY);
480 return keyring_search_aux(keyring, current->cred,
481 type, description, type->match);
483 EXPORT_SYMBOL(keyring_search);
486 * Search the given keyring only (no recursion).
488 * The caller must guarantee that the keyring is a keyring and that the
489 * permission is granted to search the keyring as no check is made here.
491 * RCU is used to make it unnecessary to lock the keyring key list here.
493 * Returns a pointer to the found key with usage count incremented if
494 * successful and returns -ENOKEY if not found. Revoked keys and keys not
495 * providing the requested permission are skipped over.
497 * If successful, the possession indicator is propagated from the keyring ref
498 * to the returned key reference.
500 key_ref_t __keyring_search_one(key_ref_t keyring_ref,
501 const struct key_type *ktype,
502 const char *description,
505 struct keyring_list *klist;
506 unsigned long possessed;
507 struct key *keyring, *key;
510 keyring = key_ref_to_ptr(keyring_ref);
511 possessed = is_key_possessed(keyring_ref);
515 klist = rcu_dereference(keyring->payload.subscriptions);
517 for (loop = 0; loop < klist->nkeys; loop++) {
518 key = klist->keys[loop];
520 if (key->type == ktype &&
521 (!key->type->match ||
522 key->type->match(key, description)) &&
523 key_permission(make_key_ref(key, possessed),
525 !test_bit(KEY_FLAG_REVOKED, &key->flags)
532 return ERR_PTR(-ENOKEY);
535 atomic_inc(&key->usage);
537 return make_key_ref(key, possessed);
541 * Find a keyring with the specified name.
543 * All named keyrings in the current user namespace are searched, provided they
544 * grant Search permission directly to the caller (unless this check is
545 * skipped). Keyrings whose usage points have reached zero or who have been
546 * revoked are skipped.
548 * Returns a pointer to the keyring with the keyring's refcount having being
549 * incremented on success. -ENOKEY is returned if a key could not be found.
551 struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
557 return ERR_PTR(-EINVAL);
559 bucket = keyring_hash(name);
561 read_lock(&keyring_name_lock);
563 if (keyring_name_hash[bucket].next) {
564 /* search this hash bucket for a keyring with a matching name
565 * that's readable and that hasn't been revoked */
566 list_for_each_entry(keyring,
567 &keyring_name_hash[bucket],
570 if (keyring->user->user_ns != current_user_ns())
573 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
576 if (strcmp(keyring->description, name) != 0)
579 if (!skip_perm_check &&
580 key_permission(make_key_ref(keyring, 0),
584 /* we've got a match but we might end up racing with
585 * key_cleanup() if the keyring is currently 'dead'
586 * (ie. it has a zero usage count) */
587 if (!atomic_inc_not_zero(&keyring->usage))
593 keyring = ERR_PTR(-ENOKEY);
595 read_unlock(&keyring_name_lock);
600 * See if a cycle will will be created by inserting acyclic tree B in acyclic
601 * tree A at the topmost level (ie: as a direct child of A).
603 * Since we are adding B to A at the top level, checking for cycles should just
604 * be a matter of seeing if node A is somewhere in tree B.
606 static int keyring_detect_cycle(struct key *A, struct key *B)
609 struct keyring_list *keylist;
611 } stack[KEYRING_SEARCH_MAX_DEPTH];
613 struct keyring_list *keylist;
614 struct key *subtree, *key;
626 /* start processing a new keyring */
628 if (test_bit(KEY_FLAG_REVOKED, &subtree->flags))
629 goto not_this_keyring;
631 keylist = rcu_dereference(subtree->payload.subscriptions);
633 goto not_this_keyring;
637 /* iterate through the remaining keys in this keyring */
638 for (; kix < keylist->nkeys; kix++) {
639 key = keylist->keys[kix];
644 /* recursively check nested keyrings */
645 if (key->type == &key_type_keyring) {
646 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
649 /* stack the current position */
650 stack[sp].keylist = keylist;
654 /* begin again with the new keyring */
660 /* the keyring we're looking at was disqualified or didn't contain a
664 /* resume the checking of a keyring higher up in the tree */
666 keylist = stack[sp].keylist;
667 kix = stack[sp].kix + 1;
671 ret = 0; /* no cycles detected */
687 * Dispose of a keyring list after the RCU grace period, freeing the unlinked
690 static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
692 struct keyring_list *klist =
693 container_of(rcu, struct keyring_list, rcu);
695 if (klist->delkey != USHRT_MAX)
696 key_put(klist->keys[klist->delkey]);
701 * Preallocate memory so that a key can be linked into to a keyring.
703 int __key_link_begin(struct key *keyring, const struct key_type *type,
704 const char *description, unsigned long *_prealloc)
705 __acquires(&keyring->sem)
707 struct keyring_list *klist, *nklist;
708 unsigned long prealloc;
713 kenter("%d,%s,%s,", key_serial(keyring), type->name, description);
715 if (keyring->type != &key_type_keyring)
718 down_write(&keyring->sem);
721 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
724 /* serialise link/link calls to prevent parallel calls causing a cycle
725 * when linking two keyring in opposite orders */
726 if (type == &key_type_keyring)
727 down_write(&keyring_serialise_link_sem);
729 klist = rcu_dereference_locked_keyring(keyring);
731 /* see if there's a matching key we can displace */
732 if (klist && klist->nkeys > 0) {
733 for (loop = klist->nkeys - 1; loop >= 0; loop--) {
734 if (klist->keys[loop]->type == type &&
735 strcmp(klist->keys[loop]->description,
738 /* found a match - we'll replace this one with
740 size = sizeof(struct key *) * klist->maxkeys;
741 size += sizeof(*klist);
742 BUG_ON(size > PAGE_SIZE);
745 nklist = kmemdup(klist, size, GFP_KERNEL);
749 /* note replacement slot */
750 klist->delkey = nklist->delkey = loop;
751 prealloc = (unsigned long)nklist;
757 /* check that we aren't going to overrun the user's quota */
758 ret = key_payload_reserve(keyring,
759 keyring->datalen + KEYQUOTA_LINK_BYTES);
763 if (klist && klist->nkeys < klist->maxkeys) {
764 /* there's sufficient slack space to append directly */
766 prealloc = KEY_LINK_FIXQUOTA;
768 /* grow the key list */
771 max += klist->maxkeys;
774 if (max > USHRT_MAX - 1)
776 size = sizeof(*klist) + sizeof(struct key *) * max;
777 if (size > PAGE_SIZE)
781 nklist = kmalloc(size, GFP_KERNEL);
785 nklist->maxkeys = max;
787 memcpy(nklist->keys, klist->keys,
788 sizeof(struct key *) * klist->nkeys);
789 nklist->delkey = klist->nkeys;
790 nklist->nkeys = klist->nkeys + 1;
791 klist->delkey = USHRT_MAX;
797 /* add the key into the new space */
798 nklist->keys[nklist->delkey] = NULL;
801 prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA;
803 *_prealloc = prealloc;
808 /* undo the quota changes */
809 key_payload_reserve(keyring,
810 keyring->datalen - KEYQUOTA_LINK_BYTES);
812 if (type == &key_type_keyring)
813 up_write(&keyring_serialise_link_sem);
815 up_write(&keyring->sem);
816 kleave(" = %d", ret);
821 * Check already instantiated keys aren't going to be a problem.
823 * The caller must have called __key_link_begin(). Don't need to call this for
824 * keys that were created since __key_link_begin() was called.
826 int __key_link_check_live_key(struct key *keyring, struct key *key)
828 if (key->type == &key_type_keyring)
829 /* check that we aren't going to create a cycle by linking one
830 * keyring to another */
831 return keyring_detect_cycle(keyring, key);
836 * Link a key into to a keyring.
838 * Must be called with __key_link_begin() having being called. Discards any
839 * already extant link to matching key if there is one, so that each keyring
840 * holds at most one link to any given key of a particular type+description
843 void __key_link(struct key *keyring, struct key *key,
844 unsigned long *_prealloc)
846 struct keyring_list *klist, *nklist;
848 nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA);
851 kenter("%d,%d,%p", keyring->serial, key->serial, nklist);
853 klist = rcu_dereference_protected(keyring->payload.subscriptions,
854 rwsem_is_locked(&keyring->sem));
856 atomic_inc(&key->usage);
858 /* there's a matching key we can displace or an empty slot in a newly
859 * allocated list we can fill */
861 kdebug("replace %hu/%hu/%hu",
862 nklist->delkey, nklist->nkeys, nklist->maxkeys);
864 nklist->keys[nklist->delkey] = key;
866 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
868 /* dispose of the old keyring list and, if there was one, the
871 kdebug("dispose %hu/%hu/%hu",
872 klist->delkey, klist->nkeys, klist->maxkeys);
873 call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
876 /* there's sufficient slack space to append directly */
877 klist->keys[klist->nkeys] = key;
884 * Finish linking a key into to a keyring.
886 * Must be called with __key_link_begin() having being called.
888 void __key_link_end(struct key *keyring, struct key_type *type,
889 unsigned long prealloc)
890 __releases(&keyring->sem)
892 BUG_ON(type == NULL);
893 BUG_ON(type->name == NULL);
894 kenter("%d,%s,%lx", keyring->serial, type->name, prealloc);
896 if (type == &key_type_keyring)
897 up_write(&keyring_serialise_link_sem);
900 if (prealloc & KEY_LINK_FIXQUOTA)
901 key_payload_reserve(keyring,
903 KEYQUOTA_LINK_BYTES);
904 kfree((struct keyring_list *)(prealloc & ~KEY_LINK_FIXQUOTA));
906 up_write(&keyring->sem);
910 * key_link - Link a key to a keyring
911 * @keyring: The keyring to make the link in.
912 * @key: The key to link to.
914 * Make a link in a keyring to a key, such that the keyring holds a reference
915 * on that key and the key can potentially be found by searching that keyring.
917 * This function will write-lock the keyring's semaphore and will consume some
918 * of the user's key data quota to hold the link.
920 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
921 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
922 * full, -EDQUOT if there is insufficient key data quota remaining to add
923 * another link or -ENOMEM if there's insufficient memory.
925 * It is assumed that the caller has checked that it is permitted for a link to
926 * be made (the keyring should have Write permission and the key Link
929 int key_link(struct key *keyring, struct key *key)
931 unsigned long prealloc;
937 ret = __key_link_begin(keyring, key->type, key->description, &prealloc);
939 ret = __key_link_check_live_key(keyring, key);
941 __key_link(keyring, key, &prealloc);
942 __key_link_end(keyring, key->type, prealloc);
947 EXPORT_SYMBOL(key_link);
950 * key_unlink - Unlink the first link to a key from a keyring.
951 * @keyring: The keyring to remove the link from.
952 * @key: The key the link is to.
954 * Remove a link from a keyring to a key.
956 * This function will write-lock the keyring's semaphore.
958 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
959 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
962 * It is assumed that the caller has checked that it is permitted for a link to
963 * be removed (the keyring should have Write permission; no permissions are
964 * required on the key).
966 int key_unlink(struct key *keyring, struct key *key)
968 struct keyring_list *klist, *nklist;
975 if (keyring->type != &key_type_keyring)
978 down_write(&keyring->sem);
980 klist = rcu_dereference_locked_keyring(keyring);
982 /* search the keyring for the key */
983 for (loop = 0; loop < klist->nkeys; loop++)
984 if (klist->keys[loop] == key)
988 up_write(&keyring->sem);
993 /* we need to copy the key list for RCU purposes */
994 nklist = kmalloc(sizeof(*klist) +
995 sizeof(struct key *) * klist->maxkeys,
999 nklist->maxkeys = klist->maxkeys;
1000 nklist->nkeys = klist->nkeys - 1;
1003 memcpy(&nklist->keys[0],
1005 loop * sizeof(struct key *));
1007 if (loop < nklist->nkeys)
1008 memcpy(&nklist->keys[loop],
1009 &klist->keys[loop + 1],
1010 (nklist->nkeys - loop) * sizeof(struct key *));
1012 /* adjust the user's quota */
1013 key_payload_reserve(keyring,
1014 keyring->datalen - KEYQUOTA_LINK_BYTES);
1016 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
1018 up_write(&keyring->sem);
1020 /* schedule for later cleanup */
1021 klist->delkey = loop;
1022 call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
1030 up_write(&keyring->sem);
1033 EXPORT_SYMBOL(key_unlink);
1036 * Dispose of a keyring list after the RCU grace period, releasing the keys it
1039 static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
1041 struct keyring_list *klist;
1044 klist = container_of(rcu, struct keyring_list, rcu);
1046 for (loop = klist->nkeys - 1; loop >= 0; loop--)
1047 key_put(klist->keys[loop]);
1053 * keyring_clear - Clear a keyring
1054 * @keyring: The keyring to clear.
1056 * Clear the contents of the specified keyring.
1058 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1060 int keyring_clear(struct key *keyring)
1062 struct keyring_list *klist;
1066 if (keyring->type == &key_type_keyring) {
1067 /* detach the pointer block with the locks held */
1068 down_write(&keyring->sem);
1070 klist = rcu_dereference_locked_keyring(keyring);
1072 /* adjust the quota */
1073 key_payload_reserve(keyring,
1074 sizeof(struct keyring_list));
1076 rcu_assign_pointer(keyring->payload.subscriptions,
1080 up_write(&keyring->sem);
1082 /* free the keys after the locks have been dropped */
1084 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1091 EXPORT_SYMBOL(keyring_clear);
1094 * Dispose of the links from a revoked keyring.
1096 * This is called with the key sem write-locked.
1098 static void keyring_revoke(struct key *keyring)
1100 struct keyring_list *klist;
1102 klist = rcu_dereference_locked_keyring(keyring);
1104 /* adjust the quota */
1105 key_payload_reserve(keyring, 0);
1108 rcu_assign_pointer(keyring->payload.subscriptions, NULL);
1109 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1114 * Determine whether a key is dead.
1116 static bool key_is_dead(struct key *key, time_t limit)
1118 return test_bit(KEY_FLAG_DEAD, &key->flags) ||
1119 (key->expiry > 0 && key->expiry <= limit);
1123 * Collect garbage from the contents of a keyring, replacing the old list with
1124 * a new one with the pointers all shuffled down.
1126 * Dead keys are classed as oned that are flagged as being dead or are revoked,
1127 * expired or negative keys that were revoked or expired before the specified
1130 void keyring_gc(struct key *keyring, time_t limit)
1132 struct keyring_list *klist, *new;
1134 int loop, keep, max;
1136 kenter("{%x,%s}", key_serial(keyring), keyring->description);
1138 down_write(&keyring->sem);
1140 klist = rcu_dereference_locked_keyring(keyring);
1144 /* work out how many subscriptions we're keeping */
1146 for (loop = klist->nkeys - 1; loop >= 0; loop--)
1147 if (!key_is_dead(klist->keys[loop], limit))
1150 if (keep == klist->nkeys)
1153 /* allocate a new keyring payload */
1154 max = roundup(keep, 4);
1155 new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *),
1163 /* install the live keys
1164 * - must take care as expired keys may be updated back to life
1167 for (loop = klist->nkeys - 1; loop >= 0; loop--) {
1168 key = klist->keys[loop];
1169 if (!key_is_dead(key, limit)) {
1172 new->keys[keep++] = key_get(key);
1177 /* adjust the quota */
1178 key_payload_reserve(keyring,
1179 sizeof(struct keyring_list) +
1180 KEYQUOTA_LINK_BYTES * keep);
1183 rcu_assign_pointer(keyring->payload.subscriptions, NULL);
1186 rcu_assign_pointer(keyring->payload.subscriptions, new);
1189 up_write(&keyring->sem);
1191 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1197 keyring_clear_rcu_disposal(&new->rcu);
1198 up_write(&keyring->sem);
1199 kleave(" [discard]");
1203 up_write(&keyring->sem);
1204 kleave(" [no dead]");
1208 up_write(&keyring->sem);
1209 kleave(" [no_klist]");
1213 up_write(&keyring->sem);