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 atomic_read(&keyring->usage) == 0);
160 for (loop = klist->nkeys - 1; loop >= 0; loop--)
161 key_put(klist->keys[loop]);
167 * Describe a keyring for /proc.
169 static void keyring_describe(const struct key *keyring, struct seq_file *m)
171 struct keyring_list *klist;
173 if (keyring->description)
174 seq_puts(m, keyring->description);
176 seq_puts(m, "[anon]");
178 if (key_is_instantiated(keyring)) {
180 klist = rcu_dereference(keyring->payload.subscriptions);
182 seq_printf(m, ": %u/%u", klist->nkeys, klist->maxkeys);
184 seq_puts(m, ": empty");
190 * Read a list of key IDs from the keyring's contents in binary form
192 * The keyring's semaphore is read-locked by the caller.
194 static long keyring_read(const struct key *keyring,
195 char __user *buffer, size_t buflen)
197 struct keyring_list *klist;
203 klist = rcu_dereference_locked_keyring(keyring);
205 /* calculate how much data we could return */
206 qty = klist->nkeys * sizeof(key_serial_t);
208 if (buffer && buflen > 0) {
212 /* copy the IDs of the subscribed keys into the
216 for (loop = 0; loop < klist->nkeys; loop++) {
217 key = klist->keys[loop];
219 tmp = sizeof(key_serial_t);
223 if (copy_to_user(buffer,
243 * Allocate a keyring and link into the destination keyring.
245 struct key *keyring_alloc(const char *description, uid_t uid, gid_t gid,
246 const struct cred *cred, unsigned long flags,
252 keyring = key_alloc(&key_type_keyring, description,
254 (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
257 if (!IS_ERR(keyring)) {
258 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
261 keyring = ERR_PTR(ret);
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
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.
284 * The search is performed as a breadth-then-depth search up to the prescribed
285 * limit (KEYRING_SEARCH_MAX_DEPTH).
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
293 * RCU is used to prevent the keyring key lists from disappearing without the
294 * need to take lots of locks.
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.
301 * In the case of a successful return, the possession attribute from
302 * @keyring_ref is propagated to the returned key reference.
304 key_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,
312 struct keyring_list *keylist;
314 } stack[KEYRING_SEARCH_MAX_DEPTH];
316 struct keyring_list *keylist;
318 unsigned long possessed, kflags;
319 struct key *keyring, *key;
324 keyring = key_ref_to_ptr(keyring_ref);
325 possessed = is_key_possessed(keyring_ref);
328 /* top keyring must have search permission to begin the search */
329 err = key_task_permission(keyring_ref, cred, KEY_SEARCH);
331 key_ref = ERR_PTR(err);
335 key_ref = ERR_PTR(-ENOTDIR);
336 if (keyring->type != &key_type_keyring)
341 now = current_kernel_time();
345 /* firstly we should check to see if this top-level keyring is what we
347 key_ref = ERR_PTR(-EAGAIN);
348 kflags = keyring->flags;
349 if (keyring->type == type && match(keyring, description)) {
354 /* check it isn't negative and hasn't expired or been
356 if (kflags & (1 << KEY_FLAG_REVOKED))
358 if (key->expiry && now.tv_sec >= key->expiry)
360 key_ref = ERR_PTR(key->type_data.reject_error);
361 if (kflags & (1 << KEY_FLAG_NEGATIVE))
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))
373 /* start processing a new keyring */
375 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
376 goto not_this_keyring;
378 keylist = rcu_dereference(keyring->payload.subscriptions);
380 goto not_this_keyring;
382 /* iterate through the keys in this keyring first */
383 nkeys = keylist->nkeys;
385 for (kix = 0; kix < nkeys; kix++) {
386 key = keylist->keys[kix];
389 /* ignore keys not of this type */
390 if (key->type != type)
393 /* skip revoked keys and expired keys */
394 if (!no_state_check) {
395 if (kflags & (1 << KEY_FLAG_REVOKED))
398 if (key->expiry && now.tv_sec >= key->expiry)
402 /* keys that don't match */
403 if (!match(key, description))
406 /* key must have search permissions */
407 if (key_task_permission(make_key_ref(key, possessed),
408 cred, KEY_SEARCH) < 0)
414 /* we set a different error code if we pass a negative key */
415 if (kflags & (1 << KEY_FLAG_NEGATIVE)) {
416 err = key->type_data.reject_error;
423 /* search through the keyrings nested in this one */
426 nkeys = keylist->nkeys;
428 for (; kix < nkeys; kix++) {
429 key = keylist->keys[kix];
430 if (key->type != &key_type_keyring)
433 /* recursively search nested keyrings
434 * - only search keyrings for which we have search permission
436 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
439 if (key_task_permission(make_key_ref(key, possessed),
440 cred, KEY_SEARCH) < 0)
443 /* stack the current position */
444 stack[sp].keylist = keylist;
448 /* begin again with the new keyring */
453 /* the keyring we're looking at was disqualified or didn't contain a
457 /* resume the processing of a keyring higher up in the tree */
459 keylist = stack[sp].keylist;
460 kix = stack[sp].kix + 1;
464 key_ref = ERR_PTR(err);
467 /* we found a viable match */
469 atomic_inc(&key->usage);
471 key_ref = make_key_ref(key, possessed);
479 * keyring_search - Search the supplied keyring tree for a matching key
480 * @keyring: The root of the keyring tree to be searched.
481 * @type: The type of keyring we want to find.
482 * @description: The name of the keyring we want to find.
484 * As keyring_search_aux() above, but using the current task's credentials and
485 * type's default matching function.
487 key_ref_t keyring_search(key_ref_t keyring,
488 struct key_type *type,
489 const char *description)
492 return ERR_PTR(-ENOKEY);
494 return keyring_search_aux(keyring, current->cred,
495 type, description, type->match, false);
497 EXPORT_SYMBOL(keyring_search);
500 * Search the given keyring only (no recursion).
502 * The caller must guarantee that the keyring is a keyring and that the
503 * permission is granted to search the keyring as no check is made here.
505 * RCU is used to make it unnecessary to lock the keyring key list here.
507 * Returns a pointer to the found key with usage count incremented if
508 * successful and returns -ENOKEY if not found. Revoked keys and keys not
509 * providing the requested permission are skipped over.
511 * If successful, the possession indicator is propagated from the keyring ref
512 * to the returned key reference.
514 key_ref_t __keyring_search_one(key_ref_t keyring_ref,
515 const struct key_type *ktype,
516 const char *description,
519 struct keyring_list *klist;
520 unsigned long possessed;
521 struct key *keyring, *key;
524 keyring = key_ref_to_ptr(keyring_ref);
525 possessed = is_key_possessed(keyring_ref);
529 klist = rcu_dereference(keyring->payload.subscriptions);
531 nkeys = klist->nkeys;
533 for (loop = 0; loop < nkeys ; loop++) {
534 key = klist->keys[loop];
536 if (key->type == ktype &&
537 (!key->type->match ||
538 key->type->match(key, description)) &&
539 key_permission(make_key_ref(key, possessed),
541 !test_bit(KEY_FLAG_REVOKED, &key->flags)
548 return ERR_PTR(-ENOKEY);
551 atomic_inc(&key->usage);
553 return make_key_ref(key, possessed);
557 * Find a keyring with the specified name.
559 * All named keyrings in the current user namespace are searched, provided they
560 * grant Search permission directly to the caller (unless this check is
561 * skipped). Keyrings whose usage points have reached zero or who have been
562 * revoked are skipped.
564 * Returns a pointer to the keyring with the keyring's refcount having being
565 * incremented on success. -ENOKEY is returned if a key could not be found.
567 struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
573 return ERR_PTR(-EINVAL);
575 bucket = keyring_hash(name);
577 read_lock(&keyring_name_lock);
579 if (keyring_name_hash[bucket].next) {
580 /* search this hash bucket for a keyring with a matching name
581 * that's readable and that hasn't been revoked */
582 list_for_each_entry(keyring,
583 &keyring_name_hash[bucket],
586 if (keyring->user->user_ns != current_user_ns())
589 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
592 if (strcmp(keyring->description, name) != 0)
595 if (!skip_perm_check &&
596 key_permission(make_key_ref(keyring, 0),
600 /* we've got a match but we might end up racing with
601 * key_cleanup() if the keyring is currently 'dead'
602 * (ie. it has a zero usage count) */
603 if (!atomic_inc_not_zero(&keyring->usage))
609 keyring = ERR_PTR(-ENOKEY);
611 read_unlock(&keyring_name_lock);
616 * See if a cycle will will be created by inserting acyclic tree B in acyclic
617 * tree A at the topmost level (ie: as a direct child of A).
619 * Since we are adding B to A at the top level, checking for cycles should just
620 * be a matter of seeing if node A is somewhere in tree B.
622 static int keyring_detect_cycle(struct key *A, struct key *B)
625 struct keyring_list *keylist;
627 } stack[KEYRING_SEARCH_MAX_DEPTH];
629 struct keyring_list *keylist;
630 struct key *subtree, *key;
631 int sp, nkeys, kix, ret;
642 /* start processing a new keyring */
644 if (test_bit(KEY_FLAG_REVOKED, &subtree->flags))
645 goto not_this_keyring;
647 keylist = rcu_dereference(subtree->payload.subscriptions);
649 goto not_this_keyring;
653 /* iterate through the remaining keys in this keyring */
654 nkeys = keylist->nkeys;
656 for (; kix < nkeys; kix++) {
657 key = keylist->keys[kix];
662 /* recursively check nested keyrings */
663 if (key->type == &key_type_keyring) {
664 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
667 /* stack the current position */
668 stack[sp].keylist = keylist;
672 /* begin again with the new keyring */
678 /* the keyring we're looking at was disqualified or didn't contain a
682 /* resume the checking of a keyring higher up in the tree */
684 keylist = stack[sp].keylist;
685 kix = stack[sp].kix + 1;
689 ret = 0; /* no cycles detected */
705 * Dispose of a keyring list after the RCU grace period, freeing the unlinked
708 static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
710 struct keyring_list *klist =
711 container_of(rcu, struct keyring_list, rcu);
713 if (klist->delkey != USHRT_MAX)
714 key_put(klist->keys[klist->delkey]);
719 * Preallocate memory so that a key can be linked into to a keyring.
721 int __key_link_begin(struct key *keyring, const struct key_type *type,
722 const char *description, unsigned long *_prealloc)
723 __acquires(&keyring->sem)
725 struct keyring_list *klist, *nklist;
726 unsigned long prealloc;
731 kenter("%d,%s,%s,", key_serial(keyring), type->name, description);
733 if (keyring->type != &key_type_keyring)
736 down_write(&keyring->sem);
739 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
742 /* serialise link/link calls to prevent parallel calls causing a cycle
743 * when linking two keyring in opposite orders */
744 if (type == &key_type_keyring)
745 down_write(&keyring_serialise_link_sem);
747 klist = rcu_dereference_locked_keyring(keyring);
749 /* see if there's a matching key we can displace */
750 if (klist && klist->nkeys > 0) {
751 for (loop = klist->nkeys - 1; loop >= 0; loop--) {
752 if (klist->keys[loop]->type == type &&
753 strcmp(klist->keys[loop]->description,
756 /* found a match - we'll replace this one with
758 size = sizeof(struct key *) * klist->maxkeys;
759 size += sizeof(*klist);
760 BUG_ON(size > PAGE_SIZE);
763 nklist = kmemdup(klist, size, GFP_KERNEL);
767 /* note replacement slot */
768 klist->delkey = nklist->delkey = loop;
769 prealloc = (unsigned long)nklist;
775 /* check that we aren't going to overrun the user's quota */
776 ret = key_payload_reserve(keyring,
777 keyring->datalen + KEYQUOTA_LINK_BYTES);
781 if (klist && klist->nkeys < klist->maxkeys) {
782 /* there's sufficient slack space to append directly */
784 prealloc = KEY_LINK_FIXQUOTA;
786 /* grow the key list */
789 max += klist->maxkeys;
792 if (max > USHRT_MAX - 1)
794 size = sizeof(*klist) + sizeof(struct key *) * max;
795 if (size > PAGE_SIZE)
799 nklist = kmalloc(size, GFP_KERNEL);
803 nklist->maxkeys = max;
805 memcpy(nklist->keys, klist->keys,
806 sizeof(struct key *) * klist->nkeys);
807 nklist->delkey = klist->nkeys;
808 nklist->nkeys = klist->nkeys + 1;
809 klist->delkey = USHRT_MAX;
815 /* add the key into the new space */
816 nklist->keys[nklist->delkey] = NULL;
819 prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA;
821 *_prealloc = prealloc;
826 /* undo the quota changes */
827 key_payload_reserve(keyring,
828 keyring->datalen - KEYQUOTA_LINK_BYTES);
830 if (type == &key_type_keyring)
831 up_write(&keyring_serialise_link_sem);
833 up_write(&keyring->sem);
834 kleave(" = %d", ret);
839 * Check already instantiated keys aren't going to be a problem.
841 * The caller must have called __key_link_begin(). Don't need to call this for
842 * keys that were created since __key_link_begin() was called.
844 int __key_link_check_live_key(struct key *keyring, struct key *key)
846 if (key->type == &key_type_keyring)
847 /* check that we aren't going to create a cycle by linking one
848 * keyring to another */
849 return keyring_detect_cycle(keyring, key);
854 * Link a key into to a keyring.
856 * Must be called with __key_link_begin() having being called. Discards any
857 * already extant link to matching key if there is one, so that each keyring
858 * holds at most one link to any given key of a particular type+description
861 void __key_link(struct key *keyring, struct key *key,
862 unsigned long *_prealloc)
864 struct keyring_list *klist, *nklist;
866 nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA);
869 kenter("%d,%d,%p", keyring->serial, key->serial, nklist);
871 klist = rcu_dereference_locked_keyring(keyring);
873 atomic_inc(&key->usage);
875 /* there's a matching key we can displace or an empty slot in a newly
876 * allocated list we can fill */
878 kdebug("replace %hu/%hu/%hu",
879 nklist->delkey, nklist->nkeys, nklist->maxkeys);
881 nklist->keys[nklist->delkey] = key;
883 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
885 /* dispose of the old keyring list and, if there was one, the
888 kdebug("dispose %hu/%hu/%hu",
889 klist->delkey, klist->nkeys, klist->maxkeys);
890 call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
893 /* there's sufficient slack space to append directly */
894 klist->keys[klist->nkeys] = key;
901 * Finish linking a key into to a keyring.
903 * Must be called with __key_link_begin() having being called.
905 void __key_link_end(struct key *keyring, struct key_type *type,
906 unsigned long prealloc)
907 __releases(&keyring->sem)
909 BUG_ON(type == NULL);
910 BUG_ON(type->name == NULL);
911 kenter("%d,%s,%lx", keyring->serial, type->name, prealloc);
913 if (type == &key_type_keyring)
914 up_write(&keyring_serialise_link_sem);
917 if (prealloc & KEY_LINK_FIXQUOTA)
918 key_payload_reserve(keyring,
920 KEYQUOTA_LINK_BYTES);
921 kfree((struct keyring_list *)(prealloc & ~KEY_LINK_FIXQUOTA));
923 up_write(&keyring->sem);
927 * key_link - Link a key to a keyring
928 * @keyring: The keyring to make the link in.
929 * @key: The key to link to.
931 * Make a link in a keyring to a key, such that the keyring holds a reference
932 * on that key and the key can potentially be found by searching that keyring.
934 * This function will write-lock the keyring's semaphore and will consume some
935 * of the user's key data quota to hold the link.
937 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
938 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
939 * full, -EDQUOT if there is insufficient key data quota remaining to add
940 * another link or -ENOMEM if there's insufficient memory.
942 * It is assumed that the caller has checked that it is permitted for a link to
943 * be made (the keyring should have Write permission and the key Link
946 int key_link(struct key *keyring, struct key *key)
948 unsigned long prealloc;
954 ret = __key_link_begin(keyring, key->type, key->description, &prealloc);
956 ret = __key_link_check_live_key(keyring, key);
958 __key_link(keyring, key, &prealloc);
959 __key_link_end(keyring, key->type, prealloc);
964 EXPORT_SYMBOL(key_link);
967 * key_unlink - Unlink the first link to a key from a keyring.
968 * @keyring: The keyring to remove the link from.
969 * @key: The key the link is to.
971 * Remove a link from a keyring to a key.
973 * This function will write-lock the keyring's semaphore.
975 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
976 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
979 * It is assumed that the caller has checked that it is permitted for a link to
980 * be removed (the keyring should have Write permission; no permissions are
981 * required on the key).
983 int key_unlink(struct key *keyring, struct key *key)
985 struct keyring_list *klist, *nklist;
992 if (keyring->type != &key_type_keyring)
995 down_write(&keyring->sem);
997 klist = rcu_dereference_locked_keyring(keyring);
999 /* search the keyring for the key */
1000 for (loop = 0; loop < klist->nkeys; loop++)
1001 if (klist->keys[loop] == key)
1002 goto key_is_present;
1005 up_write(&keyring->sem);
1010 /* we need to copy the key list for RCU purposes */
1011 nklist = kmalloc(sizeof(*klist) +
1012 sizeof(struct key *) * klist->maxkeys,
1016 nklist->maxkeys = klist->maxkeys;
1017 nklist->nkeys = klist->nkeys - 1;
1020 memcpy(&nklist->keys[0],
1022 loop * sizeof(struct key *));
1024 if (loop < nklist->nkeys)
1025 memcpy(&nklist->keys[loop],
1026 &klist->keys[loop + 1],
1027 (nklist->nkeys - loop) * sizeof(struct key *));
1029 /* adjust the user's quota */
1030 key_payload_reserve(keyring,
1031 keyring->datalen - KEYQUOTA_LINK_BYTES);
1033 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
1035 up_write(&keyring->sem);
1037 /* schedule for later cleanup */
1038 klist->delkey = loop;
1039 call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
1047 up_write(&keyring->sem);
1050 EXPORT_SYMBOL(key_unlink);
1053 * Dispose of a keyring list after the RCU grace period, releasing the keys it
1056 static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
1058 struct keyring_list *klist;
1061 klist = container_of(rcu, struct keyring_list, rcu);
1063 for (loop = klist->nkeys - 1; loop >= 0; loop--)
1064 key_put(klist->keys[loop]);
1070 * keyring_clear - Clear a keyring
1071 * @keyring: The keyring to clear.
1073 * Clear the contents of the specified keyring.
1075 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1077 int keyring_clear(struct key *keyring)
1079 struct keyring_list *klist;
1083 if (keyring->type == &key_type_keyring) {
1084 /* detach the pointer block with the locks held */
1085 down_write(&keyring->sem);
1087 klist = rcu_dereference_locked_keyring(keyring);
1089 /* adjust the quota */
1090 key_payload_reserve(keyring,
1091 sizeof(struct keyring_list));
1093 rcu_assign_pointer(keyring->payload.subscriptions,
1097 up_write(&keyring->sem);
1099 /* free the keys after the locks have been dropped */
1101 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1108 EXPORT_SYMBOL(keyring_clear);
1111 * Dispose of the links from a revoked keyring.
1113 * This is called with the key sem write-locked.
1115 static void keyring_revoke(struct key *keyring)
1117 struct keyring_list *klist;
1119 klist = rcu_dereference_locked_keyring(keyring);
1121 /* adjust the quota */
1122 key_payload_reserve(keyring, 0);
1125 rcu_assign_pointer(keyring->payload.subscriptions, NULL);
1126 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1131 * Determine whether a key is dead.
1133 static bool key_is_dead(struct key *key, time_t limit)
1135 return test_bit(KEY_FLAG_DEAD, &key->flags) ||
1136 (key->expiry > 0 && key->expiry <= limit);
1140 * Collect garbage from the contents of a keyring, replacing the old list with
1141 * a new one with the pointers all shuffled down.
1143 * Dead keys are classed as oned that are flagged as being dead or are revoked,
1144 * expired or negative keys that were revoked or expired before the specified
1147 void keyring_gc(struct key *keyring, time_t limit)
1149 struct keyring_list *klist, *new;
1151 int loop, keep, max;
1153 kenter("{%x,%s}", key_serial(keyring), keyring->description);
1155 down_write(&keyring->sem);
1157 klist = rcu_dereference_locked_keyring(keyring);
1161 /* work out how many subscriptions we're keeping */
1163 for (loop = klist->nkeys - 1; loop >= 0; loop--)
1164 if (!key_is_dead(klist->keys[loop], limit))
1167 if (keep == klist->nkeys)
1170 /* allocate a new keyring payload */
1171 max = roundup(keep, 4);
1172 new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *),
1180 /* install the live keys
1181 * - must take care as expired keys may be updated back to life
1184 for (loop = klist->nkeys - 1; loop >= 0; loop--) {
1185 key = klist->keys[loop];
1186 if (!key_is_dead(key, limit)) {
1189 new->keys[keep++] = key_get(key);
1194 /* adjust the quota */
1195 key_payload_reserve(keyring,
1196 sizeof(struct keyring_list) +
1197 KEYQUOTA_LINK_BYTES * keep);
1200 rcu_assign_pointer(keyring->payload.subscriptions, NULL);
1203 rcu_assign_pointer(keyring->payload.subscriptions, new);
1206 up_write(&keyring->sem);
1208 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1214 keyring_clear_rcu_disposal(&new->rcu);
1215 up_write(&keyring->sem);
1216 kleave(" [discard]");
1220 up_write(&keyring->sem);
1221 kleave(" [no dead]");
1225 up_write(&keyring->sem);
1226 kleave(" [no_klist]");
1230 up_write(&keyring->sem);