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)
340 return ERR_PTR(-ENOKEY);
344 now = current_kernel_time();
348 /* firstly we should check to see if this top-level keyring is what we
350 key_ref = ERR_PTR(-EAGAIN);
351 kflags = keyring->flags;
352 if (keyring->type == type && match(keyring, description)) {
357 /* check it isn't negative and hasn't expired or been
359 if (kflags & (1 << KEY_FLAG_REVOKED))
361 if (key->expiry && now.tv_sec >= key->expiry)
363 key_ref = ERR_PTR(key->type_data.reject_error);
364 if (kflags & (1 << KEY_FLAG_NEGATIVE))
369 /* otherwise, the top keyring must not be revoked, expired, or
370 * negatively instantiated if we are to search it */
371 key_ref = ERR_PTR(-EAGAIN);
372 if (kflags & ((1 << KEY_FLAG_REVOKED) | (1 << KEY_FLAG_NEGATIVE)) ||
373 (keyring->expiry && now.tv_sec >= keyring->expiry))
376 /* start processing a new keyring */
378 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
379 goto not_this_keyring;
381 keylist = rcu_dereference(keyring->payload.subscriptions);
383 goto not_this_keyring;
385 /* iterate through the keys in this keyring first */
386 for (kix = 0; kix < keylist->nkeys; kix++) {
387 key = keylist->keys[kix];
390 /* ignore keys not of this type */
391 if (key->type != type)
394 /* skip revoked keys and expired keys */
395 if (!no_state_check) {
396 if (kflags & (1 << KEY_FLAG_REVOKED))
399 if (key->expiry && now.tv_sec >= key->expiry)
403 /* keys that don't match */
404 if (!match(key, description))
407 /* key must have search permissions */
408 if (key_task_permission(make_key_ref(key, possessed),
409 cred, KEY_SEARCH) < 0)
415 /* we set a different error code if we pass a negative key */
416 if (kflags & (1 << KEY_FLAG_NEGATIVE)) {
417 err = key->type_data.reject_error;
424 /* search through the keyrings nested in this one */
427 for (; kix < keylist->nkeys; kix++) {
428 key = keylist->keys[kix];
429 if (key->type != &key_type_keyring)
432 /* recursively search nested keyrings
433 * - only search keyrings for which we have search permission
435 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
438 if (key_task_permission(make_key_ref(key, possessed),
439 cred, KEY_SEARCH) < 0)
442 /* stack the current position */
443 stack[sp].keylist = keylist;
447 /* begin again with the new keyring */
452 /* the keyring we're looking at was disqualified or didn't contain a
456 /* resume the processing of a keyring higher up in the tree */
458 keylist = stack[sp].keylist;
459 kix = stack[sp].kix + 1;
463 key_ref = ERR_PTR(err);
466 /* we found a viable match */
468 atomic_inc(&key->usage);
470 key_ref = make_key_ref(key, possessed);
478 * keyring_search - Search the supplied keyring tree for a matching key
479 * @keyring: The root of the keyring tree to be searched.
480 * @type: The type of keyring we want to find.
481 * @description: The name of the keyring we want to find.
483 * As keyring_search_aux() above, but using the current task's credentials and
484 * type's default matching function.
486 key_ref_t keyring_search(key_ref_t keyring,
487 struct key_type *type,
488 const char *description)
490 return keyring_search_aux(keyring, current->cred,
491 type, description, type->match, false);
493 EXPORT_SYMBOL(keyring_search);
496 * Search the given keyring only (no recursion).
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.
501 * RCU is used to make it unnecessary to lock the keyring key list here.
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.
507 * If successful, the possession indicator is propagated from the keyring ref
508 * to the returned key reference.
510 key_ref_t __keyring_search_one(key_ref_t keyring_ref,
511 const struct key_type *ktype,
512 const char *description,
515 struct keyring_list *klist;
516 unsigned long possessed;
517 struct key *keyring, *key;
520 keyring = key_ref_to_ptr(keyring_ref);
521 possessed = is_key_possessed(keyring_ref);
525 klist = rcu_dereference(keyring->payload.subscriptions);
527 for (loop = 0; loop < klist->nkeys; loop++) {
528 key = klist->keys[loop];
530 if (key->type == ktype &&
531 (!key->type->match ||
532 key->type->match(key, description)) &&
533 key_permission(make_key_ref(key, possessed),
535 !test_bit(KEY_FLAG_REVOKED, &key->flags)
542 return ERR_PTR(-ENOKEY);
545 atomic_inc(&key->usage);
547 return make_key_ref(key, possessed);
551 * Find a keyring with the specified name.
553 * Only keyrings that have nonzero refcount, are not revoked, and are owned by a
554 * user in the current user namespace are considered. If @uid_keyring is %true,
555 * the keyring additionally must have been allocated as a user or user session
556 * keyring; otherwise, it must grant Search permission directly to the caller.
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.
561 struct key *find_keyring_by_name(const char *name, bool uid_keyring)
567 return ERR_PTR(-EINVAL);
569 bucket = keyring_hash(name);
571 read_lock(&keyring_name_lock);
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],
580 if (keyring->user->user_ns != current_user_ns())
583 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
586 if (strcmp(keyring->description, name) != 0)
590 if (!test_bit(KEY_FLAG_UID_KEYRING,
594 if (key_permission(make_key_ref(keyring, 0),
599 /* we've got a match but we might end up racing with
600 * key_cleanup() if the keyring is currently 'dead'
601 * (ie. it has a zero usage count) */
602 if (!atomic_inc_not_zero(&keyring->usage))
608 keyring = ERR_PTR(-ENOKEY);
610 read_unlock(&keyring_name_lock);
615 * See if a cycle will will be created by inserting acyclic tree B in acyclic
616 * tree A at the topmost level (ie: as a direct child of A).
618 * Since we are adding B to A at the top level, checking for cycles should just
619 * be a matter of seeing if node A is somewhere in tree B.
621 static int keyring_detect_cycle(struct key *A, struct key *B)
624 struct keyring_list *keylist;
626 } stack[KEYRING_SEARCH_MAX_DEPTH];
628 struct keyring_list *keylist;
629 struct key *subtree, *key;
641 /* start processing a new keyring */
643 if (test_bit(KEY_FLAG_REVOKED, &subtree->flags))
644 goto not_this_keyring;
646 keylist = rcu_dereference(subtree->payload.subscriptions);
648 goto not_this_keyring;
652 /* iterate through the remaining keys in this keyring */
653 for (; kix < keylist->nkeys; kix++) {
654 key = keylist->keys[kix];
659 /* recursively check nested keyrings */
660 if (key->type == &key_type_keyring) {
661 if (sp >= KEYRING_SEARCH_MAX_DEPTH)
664 /* stack the current position */
665 stack[sp].keylist = keylist;
669 /* begin again with the new keyring */
675 /* the keyring we're looking at was disqualified or didn't contain a
679 /* resume the checking of a keyring higher up in the tree */
681 keylist = stack[sp].keylist;
682 kix = stack[sp].kix + 1;
686 ret = 0; /* no cycles detected */
702 * Dispose of a keyring list after the RCU grace period, freeing the unlinked
705 static void keyring_unlink_rcu_disposal(struct rcu_head *rcu)
707 struct keyring_list *klist =
708 container_of(rcu, struct keyring_list, rcu);
710 if (klist->delkey != USHRT_MAX)
711 key_put(klist->keys[klist->delkey]);
716 * Preallocate memory so that a key can be linked into to a keyring.
718 int __key_link_begin(struct key *keyring, const struct key_type *type,
719 const char *description, unsigned long *_prealloc)
720 __acquires(&keyring->sem)
722 struct keyring_list *klist, *nklist;
723 unsigned long prealloc;
728 kenter("%d,%s,%s,", key_serial(keyring), type->name, description);
730 if (keyring->type != &key_type_keyring)
733 down_write(&keyring->sem);
736 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
739 /* serialise link/link calls to prevent parallel calls causing a cycle
740 * when linking two keyring in opposite orders */
741 if (type == &key_type_keyring)
742 down_write(&keyring_serialise_link_sem);
744 klist = rcu_dereference_locked_keyring(keyring);
746 /* see if there's a matching key we can displace */
747 if (klist && klist->nkeys > 0) {
748 for (loop = klist->nkeys - 1; loop >= 0; loop--) {
749 if (klist->keys[loop]->type == type &&
750 strcmp(klist->keys[loop]->description,
753 /* found a match - we'll replace this one with
755 size = sizeof(struct key *) * klist->maxkeys;
756 size += sizeof(*klist);
757 BUG_ON(size > PAGE_SIZE);
760 nklist = kmemdup(klist, size, GFP_KERNEL);
764 /* note replacement slot */
765 klist->delkey = nklist->delkey = loop;
766 prealloc = (unsigned long)nklist;
772 /* check that we aren't going to overrun the user's quota */
773 ret = key_payload_reserve(keyring,
774 keyring->datalen + KEYQUOTA_LINK_BYTES);
778 if (klist && klist->nkeys < klist->maxkeys) {
779 /* there's sufficient slack space to append directly */
781 prealloc = KEY_LINK_FIXQUOTA;
783 /* grow the key list */
786 max += klist->maxkeys;
789 if (max > USHRT_MAX - 1)
791 size = sizeof(*klist) + sizeof(struct key *) * max;
792 if (size > PAGE_SIZE)
796 nklist = kmalloc(size, GFP_KERNEL);
800 nklist->maxkeys = max;
802 memcpy(nklist->keys, klist->keys,
803 sizeof(struct key *) * klist->nkeys);
804 nklist->delkey = klist->nkeys;
805 nklist->nkeys = klist->nkeys + 1;
806 klist->delkey = USHRT_MAX;
812 /* add the key into the new space */
813 nklist->keys[nklist->delkey] = NULL;
816 prealloc = (unsigned long)nklist | KEY_LINK_FIXQUOTA;
818 *_prealloc = prealloc;
823 /* undo the quota changes */
824 key_payload_reserve(keyring,
825 keyring->datalen - KEYQUOTA_LINK_BYTES);
827 if (type == &key_type_keyring)
828 up_write(&keyring_serialise_link_sem);
830 up_write(&keyring->sem);
831 kleave(" = %d", ret);
836 * Check already instantiated keys aren't going to be a problem.
838 * The caller must have called __key_link_begin(). Don't need to call this for
839 * keys that were created since __key_link_begin() was called.
841 int __key_link_check_live_key(struct key *keyring, struct key *key)
843 if (key->type == &key_type_keyring)
844 /* check that we aren't going to create a cycle by linking one
845 * keyring to another */
846 return keyring_detect_cycle(keyring, key);
851 * Link a key into to a keyring.
853 * Must be called with __key_link_begin() having being called. Discards any
854 * already extant link to matching key if there is one, so that each keyring
855 * holds at most one link to any given key of a particular type+description
858 void __key_link(struct key *keyring, struct key *key,
859 unsigned long *_prealloc)
861 struct keyring_list *klist, *nklist;
863 nklist = (struct keyring_list *)(*_prealloc & ~KEY_LINK_FIXQUOTA);
866 kenter("%d,%d,%p", keyring->serial, key->serial, nklist);
868 klist = rcu_dereference_locked_keyring(keyring);
870 atomic_inc(&key->usage);
872 /* there's a matching key we can displace or an empty slot in a newly
873 * allocated list we can fill */
875 kdebug("replace %hu/%hu/%hu",
876 nklist->delkey, nklist->nkeys, nklist->maxkeys);
878 nklist->keys[nklist->delkey] = key;
880 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
882 /* dispose of the old keyring list and, if there was one, the
885 kdebug("dispose %hu/%hu/%hu",
886 klist->delkey, klist->nkeys, klist->maxkeys);
887 call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
890 /* there's sufficient slack space to append directly */
891 klist->keys[klist->nkeys] = key;
898 * Finish linking a key into to a keyring.
900 * Must be called with __key_link_begin() having being called.
902 void __key_link_end(struct key *keyring, struct key_type *type,
903 unsigned long prealloc)
904 __releases(&keyring->sem)
906 BUG_ON(type == NULL);
907 BUG_ON(type->name == NULL);
908 kenter("%d,%s,%lx", keyring->serial, type->name, prealloc);
910 if (type == &key_type_keyring)
911 up_write(&keyring_serialise_link_sem);
914 if (prealloc & KEY_LINK_FIXQUOTA)
915 key_payload_reserve(keyring,
917 KEYQUOTA_LINK_BYTES);
918 kfree((struct keyring_list *)(prealloc & ~KEY_LINK_FIXQUOTA));
920 up_write(&keyring->sem);
924 * key_link - Link a key to a keyring
925 * @keyring: The keyring to make the link in.
926 * @key: The key to link to.
928 * Make a link in a keyring to a key, such that the keyring holds a reference
929 * on that key and the key can potentially be found by searching that keyring.
931 * This function will write-lock the keyring's semaphore and will consume some
932 * of the user's key data quota to hold the link.
934 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
935 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
936 * full, -EDQUOT if there is insufficient key data quota remaining to add
937 * another link or -ENOMEM if there's insufficient memory.
939 * It is assumed that the caller has checked that it is permitted for a link to
940 * be made (the keyring should have Write permission and the key Link
943 int key_link(struct key *keyring, struct key *key)
945 unsigned long prealloc;
951 ret = __key_link_begin(keyring, key->type, key->description, &prealloc);
953 ret = __key_link_check_live_key(keyring, key);
955 __key_link(keyring, key, &prealloc);
956 __key_link_end(keyring, key->type, prealloc);
961 EXPORT_SYMBOL(key_link);
964 * key_unlink - Unlink the first link to a key from a keyring.
965 * @keyring: The keyring to remove the link from.
966 * @key: The key the link is to.
968 * Remove a link from a keyring to a key.
970 * This function will write-lock the keyring's semaphore.
972 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
973 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
976 * It is assumed that the caller has checked that it is permitted for a link to
977 * be removed (the keyring should have Write permission; no permissions are
978 * required on the key).
980 int key_unlink(struct key *keyring, struct key *key)
982 struct keyring_list *klist, *nklist;
989 if (keyring->type != &key_type_keyring)
992 down_write(&keyring->sem);
994 klist = rcu_dereference_locked_keyring(keyring);
996 /* search the keyring for the key */
997 for (loop = 0; loop < klist->nkeys; loop++)
998 if (klist->keys[loop] == key)
1002 up_write(&keyring->sem);
1007 /* we need to copy the key list for RCU purposes */
1008 nklist = kmalloc(sizeof(*klist) +
1009 sizeof(struct key *) * klist->maxkeys,
1013 nklist->maxkeys = klist->maxkeys;
1014 nklist->nkeys = klist->nkeys - 1;
1017 memcpy(&nklist->keys[0],
1019 loop * sizeof(struct key *));
1021 if (loop < nklist->nkeys)
1022 memcpy(&nklist->keys[loop],
1023 &klist->keys[loop + 1],
1024 (nklist->nkeys - loop) * sizeof(struct key *));
1026 /* adjust the user's quota */
1027 key_payload_reserve(keyring,
1028 keyring->datalen - KEYQUOTA_LINK_BYTES);
1030 rcu_assign_pointer(keyring->payload.subscriptions, nklist);
1032 up_write(&keyring->sem);
1034 /* schedule for later cleanup */
1035 klist->delkey = loop;
1036 call_rcu(&klist->rcu, keyring_unlink_rcu_disposal);
1044 up_write(&keyring->sem);
1047 EXPORT_SYMBOL(key_unlink);
1050 * Dispose of a keyring list after the RCU grace period, releasing the keys it
1053 static void keyring_clear_rcu_disposal(struct rcu_head *rcu)
1055 struct keyring_list *klist;
1058 klist = container_of(rcu, struct keyring_list, rcu);
1060 for (loop = klist->nkeys - 1; loop >= 0; loop--)
1061 key_put(klist->keys[loop]);
1067 * keyring_clear - Clear a keyring
1068 * @keyring: The keyring to clear.
1070 * Clear the contents of the specified keyring.
1072 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1074 int keyring_clear(struct key *keyring)
1076 struct keyring_list *klist;
1080 if (keyring->type == &key_type_keyring) {
1081 /* detach the pointer block with the locks held */
1082 down_write(&keyring->sem);
1084 klist = rcu_dereference_locked_keyring(keyring);
1086 /* adjust the quota */
1087 key_payload_reserve(keyring,
1088 sizeof(struct keyring_list));
1090 rcu_assign_pointer(keyring->payload.subscriptions,
1094 up_write(&keyring->sem);
1096 /* free the keys after the locks have been dropped */
1098 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1105 EXPORT_SYMBOL(keyring_clear);
1108 * Dispose of the links from a revoked keyring.
1110 * This is called with the key sem write-locked.
1112 static void keyring_revoke(struct key *keyring)
1114 struct keyring_list *klist;
1116 klist = rcu_dereference_locked_keyring(keyring);
1118 /* adjust the quota */
1119 key_payload_reserve(keyring, 0);
1122 rcu_assign_pointer(keyring->payload.subscriptions, NULL);
1123 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1128 * Determine whether a key is dead.
1130 static bool key_is_dead(struct key *key, time_t limit)
1132 return test_bit(KEY_FLAG_DEAD, &key->flags) ||
1133 (key->expiry > 0 && key->expiry <= limit);
1137 * Collect garbage from the contents of a keyring, replacing the old list with
1138 * a new one with the pointers all shuffled down.
1140 * Dead keys are classed as oned that are flagged as being dead or are revoked,
1141 * expired or negative keys that were revoked or expired before the specified
1144 void keyring_gc(struct key *keyring, time_t limit)
1146 struct keyring_list *klist, *new;
1148 int loop, keep, max;
1150 kenter("{%x,%s}", key_serial(keyring), keyring->description);
1152 down_write(&keyring->sem);
1154 klist = rcu_dereference_locked_keyring(keyring);
1158 /* work out how many subscriptions we're keeping */
1160 for (loop = klist->nkeys - 1; loop >= 0; loop--)
1161 if (!key_is_dead(klist->keys[loop], limit))
1164 if (keep == klist->nkeys)
1167 /* allocate a new keyring payload */
1168 max = roundup(keep, 4);
1169 new = kmalloc(sizeof(struct keyring_list) + max * sizeof(struct key *),
1177 /* install the live keys
1178 * - must take care as expired keys may be updated back to life
1181 for (loop = klist->nkeys - 1; loop >= 0; loop--) {
1182 key = klist->keys[loop];
1183 if (!key_is_dead(key, limit)) {
1186 new->keys[keep++] = key_get(key);
1191 /* adjust the quota */
1192 key_payload_reserve(keyring,
1193 sizeof(struct keyring_list) +
1194 KEYQUOTA_LINK_BYTES * keep);
1197 rcu_assign_pointer(keyring->payload.subscriptions, NULL);
1200 rcu_assign_pointer(keyring->payload.subscriptions, new);
1203 up_write(&keyring->sem);
1205 call_rcu(&klist->rcu, keyring_clear_rcu_disposal);
1211 keyring_clear_rcu_disposal(&new->rcu);
1212 up_write(&keyring->sem);
1213 kleave(" [discard]");
1217 up_write(&keyring->sem);
1218 kleave(" [no dead]");
1222 up_write(&keyring->sem);
1223 kleave(" [no_klist]");
1227 up_write(&keyring->sem);