1 // SPDX-License-Identifier: GPL-2.0-or-later
4 * Copyright (C) 2004-2005, 2008, 2013 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
8 #include <linux/export.h>
9 #include <linux/init.h>
10 #include <linux/sched.h>
11 #include <linux/slab.h>
12 #include <linux/security.h>
13 #include <linux/seq_file.h>
14 #include <linux/err.h>
15 #include <linux/user_namespace.h>
16 #include <linux/nsproxy.h>
17 #include <keys/keyring-type.h>
18 #include <keys/user-type.h>
19 #include <linux/assoc_array_priv.h>
20 #include <linux/uaccess.h>
21 #include <net/net_namespace.h>
25 * When plumbing the depths of the key tree, this sets a hard limit
26 * set on how deep we're willing to go.
28 #define KEYRING_SEARCH_MAX_DEPTH 6
31 * We mark pointers we pass to the associative array with bit 1 set if
32 * they're keyrings and clear otherwise.
34 #define KEYRING_PTR_SUBTYPE 0x2UL
36 static inline bool keyring_ptr_is_keyring(const struct assoc_array_ptr *x)
38 return (unsigned long)x & KEYRING_PTR_SUBTYPE;
40 static inline struct key *keyring_ptr_to_key(const struct assoc_array_ptr *x)
42 void *object = assoc_array_ptr_to_leaf(x);
43 return (struct key *)((unsigned long)object & ~KEYRING_PTR_SUBTYPE);
45 static inline void *keyring_key_to_ptr(struct key *key)
47 if (key->type == &key_type_keyring)
48 return (void *)((unsigned long)key | KEYRING_PTR_SUBTYPE);
52 static DEFINE_RWLOCK(keyring_name_lock);
55 * Clean up the bits of user_namespace that belong to us.
57 void key_free_user_ns(struct user_namespace *ns)
59 write_lock(&keyring_name_lock);
60 list_del_init(&ns->keyring_name_list);
61 write_unlock(&keyring_name_lock);
63 key_put(ns->user_keyring_register);
64 #ifdef CONFIG_PERSISTENT_KEYRINGS
65 key_put(ns->persistent_keyring_register);
70 * The keyring key type definition. Keyrings are simply keys of this type and
71 * can be treated as ordinary keys in addition to having their own special
74 static int keyring_preparse(struct key_preparsed_payload *prep);
75 static void keyring_free_preparse(struct key_preparsed_payload *prep);
76 static int keyring_instantiate(struct key *keyring,
77 struct key_preparsed_payload *prep);
78 static void keyring_revoke(struct key *keyring);
79 static void keyring_destroy(struct key *keyring);
80 static void keyring_describe(const struct key *keyring, struct seq_file *m);
81 static long keyring_read(const struct key *keyring,
82 char __user *buffer, size_t buflen);
84 struct key_type key_type_keyring = {
87 .preparse = keyring_preparse,
88 .free_preparse = keyring_free_preparse,
89 .instantiate = keyring_instantiate,
90 .revoke = keyring_revoke,
91 .destroy = keyring_destroy,
92 .describe = keyring_describe,
95 EXPORT_SYMBOL(key_type_keyring);
98 * Semaphore to serialise link/link calls to prevent two link calls in parallel
99 * introducing a cycle.
101 static DEFINE_MUTEX(keyring_serialise_link_lock);
104 * Publish the name of a keyring so that it can be found by name (if it has
105 * one and it doesn't begin with a dot).
107 static void keyring_publish_name(struct key *keyring)
109 struct user_namespace *ns = current_user_ns();
111 if (keyring->description &&
112 keyring->description[0] &&
113 keyring->description[0] != '.') {
114 write_lock(&keyring_name_lock);
115 list_add_tail(&keyring->name_link, &ns->keyring_name_list);
116 write_unlock(&keyring_name_lock);
121 * Preparse a keyring payload
123 static int keyring_preparse(struct key_preparsed_payload *prep)
125 return prep->datalen != 0 ? -EINVAL : 0;
129 * Free a preparse of a user defined key payload
131 static void keyring_free_preparse(struct key_preparsed_payload *prep)
136 * Initialise a keyring.
138 * Returns 0 on success, -EINVAL if given any data.
140 static int keyring_instantiate(struct key *keyring,
141 struct key_preparsed_payload *prep)
143 assoc_array_init(&keyring->keys);
144 /* make the keyring available by name if it has one */
145 keyring_publish_name(keyring);
150 * Multiply 64-bits by 32-bits to 96-bits and fold back to 64-bit. Ideally we'd
151 * fold the carry back too, but that requires inline asm.
153 static u64 mult_64x32_and_fold(u64 x, u32 y)
155 u64 hi = (u64)(u32)(x >> 32) * y;
156 u64 lo = (u64)(u32)(x) * y;
157 return lo + ((u64)(u32)hi << 32) + (u32)(hi >> 32);
161 * Hash a key type and description.
163 static void hash_key_type_and_desc(struct keyring_index_key *index_key)
165 const unsigned level_shift = ASSOC_ARRAY_LEVEL_STEP;
166 const unsigned long fan_mask = ASSOC_ARRAY_FAN_MASK;
167 const char *description = index_key->description;
168 unsigned long hash, type;
171 int n, desc_len = index_key->desc_len;
173 type = (unsigned long)index_key->type;
174 acc = mult_64x32_and_fold(type, desc_len + 13);
175 acc = mult_64x32_and_fold(acc, 9207);
176 piece = (unsigned long)index_key->domain_tag;
177 acc = mult_64x32_and_fold(acc, piece);
178 acc = mult_64x32_and_fold(acc, 9207);
187 memcpy(&piece, description, n);
190 acc = mult_64x32_and_fold(acc, piece);
191 acc = mult_64x32_and_fold(acc, 9207);
194 /* Fold the hash down to 32 bits if need be. */
196 if (ASSOC_ARRAY_KEY_CHUNK_SIZE == 32)
199 /* Squidge all the keyrings into a separate part of the tree to
200 * ordinary keys by making sure the lowest level segment in the hash is
201 * zero for keyrings and non-zero otherwise.
203 if (index_key->type != &key_type_keyring && (hash & fan_mask) == 0)
204 hash |= (hash >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - level_shift)) | 1;
205 else if (index_key->type == &key_type_keyring && (hash & fan_mask) != 0)
206 hash = (hash + (hash << level_shift)) & ~fan_mask;
207 index_key->hash = hash;
211 * Finalise an index key to include a part of the description actually in the
212 * index key, to set the domain tag and to calculate the hash.
214 void key_set_index_key(struct keyring_index_key *index_key)
216 static struct key_tag default_domain_tag = { .usage = REFCOUNT_INIT(1), };
217 size_t n = min_t(size_t, index_key->desc_len, sizeof(index_key->desc));
219 memcpy(index_key->desc, index_key->description, n);
221 if (!index_key->domain_tag) {
222 if (index_key->type->flags & KEY_TYPE_NET_DOMAIN)
223 index_key->domain_tag = current->nsproxy->net_ns->key_domain;
225 index_key->domain_tag = &default_domain_tag;
228 hash_key_type_and_desc(index_key);
232 * key_put_tag - Release a ref on a tag.
233 * @tag: The tag to release.
235 * This releases a reference the given tag and returns true if that ref was the
238 bool key_put_tag(struct key_tag *tag)
240 if (refcount_dec_and_test(&tag->usage)) {
249 * key_remove_domain - Kill off a key domain and gc its keys
250 * @domain_tag: The domain tag to release.
252 * This marks a domain tag as being dead and releases a ref on it. If that
253 * wasn't the last reference, the garbage collector is poked to try and delete
254 * all keys that were in the domain.
256 void key_remove_domain(struct key_tag *domain_tag)
258 domain_tag->removed = true;
259 if (!key_put_tag(domain_tag))
260 key_schedule_gc_links();
264 * Build the next index key chunk.
266 * We return it one word-sized chunk at a time.
268 static unsigned long keyring_get_key_chunk(const void *data, int level)
270 const struct keyring_index_key *index_key = data;
271 unsigned long chunk = 0;
273 int desc_len = index_key->desc_len, n = sizeof(chunk);
275 level /= ASSOC_ARRAY_KEY_CHUNK_SIZE;
278 return index_key->hash;
282 return (unsigned long)index_key->type;
284 return (unsigned long)index_key->domain_tag;
287 if (desc_len <= sizeof(index_key->desc))
290 d = index_key->description + sizeof(index_key->desc);
291 d += level * sizeof(long);
292 desc_len -= sizeof(index_key->desc);
298 } while (--desc_len > 0);
303 static unsigned long keyring_get_object_key_chunk(const void *object, int level)
305 const struct key *key = keyring_ptr_to_key(object);
306 return keyring_get_key_chunk(&key->index_key, level);
309 static bool keyring_compare_object(const void *object, const void *data)
311 const struct keyring_index_key *index_key = data;
312 const struct key *key = keyring_ptr_to_key(object);
314 return key->index_key.type == index_key->type &&
315 key->index_key.domain_tag == index_key->domain_tag &&
316 key->index_key.desc_len == index_key->desc_len &&
317 memcmp(key->index_key.description, index_key->description,
318 index_key->desc_len) == 0;
322 * Compare the index keys of a pair of objects and determine the bit position
323 * at which they differ - if they differ.
325 static int keyring_diff_objects(const void *object, const void *data)
327 const struct key *key_a = keyring_ptr_to_key(object);
328 const struct keyring_index_key *a = &key_a->index_key;
329 const struct keyring_index_key *b = data;
330 unsigned long seg_a, seg_b;
336 if ((seg_a ^ seg_b) != 0)
338 level += ASSOC_ARRAY_KEY_CHUNK_SIZE / 8;
340 /* The number of bits contributed by the hash is controlled by a
341 * constant in the assoc_array headers. Everything else thereafter we
342 * can deal with as being machine word-size dependent.
346 if ((seg_a ^ seg_b) != 0)
348 level += sizeof(unsigned long);
350 /* The next bit may not work on big endian */
351 seg_a = (unsigned long)a->type;
352 seg_b = (unsigned long)b->type;
353 if ((seg_a ^ seg_b) != 0)
355 level += sizeof(unsigned long);
357 seg_a = (unsigned long)a->domain_tag;
358 seg_b = (unsigned long)b->domain_tag;
359 if ((seg_a ^ seg_b) != 0)
361 level += sizeof(unsigned long);
364 if (a->desc_len <= i)
367 for (; i < a->desc_len; i++) {
368 seg_a = *(unsigned char *)(a->description + i);
369 seg_b = *(unsigned char *)(b->description + i);
370 if ((seg_a ^ seg_b) != 0)
380 i = level * 8 + __ffs(seg_a ^ seg_b);
385 * Free an object after stripping the keyring flag off of the pointer.
387 static void keyring_free_object(void *object)
389 key_put(keyring_ptr_to_key(object));
393 * Operations for keyring management by the index-tree routines.
395 static const struct assoc_array_ops keyring_assoc_array_ops = {
396 .get_key_chunk = keyring_get_key_chunk,
397 .get_object_key_chunk = keyring_get_object_key_chunk,
398 .compare_object = keyring_compare_object,
399 .diff_objects = keyring_diff_objects,
400 .free_object = keyring_free_object,
404 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
405 * and dispose of its data.
407 * The garbage collector detects the final key_put(), removes the keyring from
408 * the serial number tree and then does RCU synchronisation before coming here,
409 * so we shouldn't need to worry about code poking around here with the RCU
410 * readlock held by this time.
412 static void keyring_destroy(struct key *keyring)
414 if (keyring->description) {
415 write_lock(&keyring_name_lock);
417 if (keyring->name_link.next != NULL &&
418 !list_empty(&keyring->name_link))
419 list_del(&keyring->name_link);
421 write_unlock(&keyring_name_lock);
424 if (keyring->restrict_link) {
425 struct key_restriction *keyres = keyring->restrict_link;
427 key_put(keyres->key);
431 assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops);
435 * Describe a keyring for /proc.
437 static void keyring_describe(const struct key *keyring, struct seq_file *m)
439 if (keyring->description)
440 seq_puts(m, keyring->description);
442 seq_puts(m, "[anon]");
444 if (key_is_positive(keyring)) {
445 if (keyring->keys.nr_leaves_on_tree != 0)
446 seq_printf(m, ": %lu", keyring->keys.nr_leaves_on_tree);
448 seq_puts(m, ": empty");
452 struct keyring_read_iterator_context {
455 key_serial_t __user *buffer;
458 static int keyring_read_iterator(const void *object, void *data)
460 struct keyring_read_iterator_context *ctx = data;
461 const struct key *key = keyring_ptr_to_key(object);
464 kenter("{%s,%d},,{%zu/%zu}",
465 key->type->name, key->serial, ctx->count, ctx->buflen);
467 if (ctx->count >= ctx->buflen)
470 ret = put_user(key->serial, ctx->buffer);
474 ctx->count += sizeof(key->serial);
479 * Read a list of key IDs from the keyring's contents in binary form
481 * The keyring's semaphore is read-locked by the caller. This prevents someone
482 * from modifying it under us - which could cause us to read key IDs multiple
485 static long keyring_read(const struct key *keyring,
486 char __user *buffer, size_t buflen)
488 struct keyring_read_iterator_context ctx;
491 kenter("{%d},,%zu", key_serial(keyring), buflen);
493 if (buflen & (sizeof(key_serial_t) - 1))
496 /* Copy as many key IDs as fit into the buffer */
497 if (buffer && buflen) {
498 ctx.buffer = (key_serial_t __user *)buffer;
501 ret = assoc_array_iterate(&keyring->keys,
502 keyring_read_iterator, &ctx);
504 kleave(" = %ld [iterate]", ret);
509 /* Return the size of the buffer needed */
510 ret = keyring->keys.nr_leaves_on_tree * sizeof(key_serial_t);
512 kleave("= %ld [ok]", ret);
514 kleave("= %ld [buffer too small]", ret);
519 * keyring_alloc - Allocate a keyring and link into the destination
520 * @description: The key description to allow the key to be searched out.
521 * @uid: The owner of the new key.
522 * @gid: The group ID for the new key's group permissions.
523 * @cred: The credentials specifying UID namespace.
524 * @acl: The ACL to attach to the new key.
525 * @flags: Flags specifying quota properties.
526 * @restrict_link: Optional link restriction for new keyrings.
527 * @dest: Destination keyring.
529 struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
530 const struct cred *cred, struct key_acl *acl,
532 struct key_restriction *restrict_link,
538 keyring = key_alloc(&key_type_keyring, description,
539 uid, gid, cred, acl, flags, restrict_link);
540 if (!IS_ERR(keyring)) {
541 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
544 keyring = ERR_PTR(ret);
550 EXPORT_SYMBOL(keyring_alloc);
553 * restrict_link_reject - Give -EPERM to restrict link
554 * @keyring: The keyring being added to.
555 * @type: The type of key being added.
556 * @payload: The payload of the key intended to be added.
557 * @restriction_key: Keys providing additional data for evaluating restriction.
559 * Reject the addition of any links to a keyring. It can be overridden by
560 * passing KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when
561 * adding a key to a keyring.
563 * This is meant to be stored in a key_restriction structure which is passed
564 * in the restrict_link parameter to keyring_alloc().
566 int restrict_link_reject(struct key *keyring,
567 const struct key_type *type,
568 const union key_payload *payload,
569 struct key *restriction_key)
575 * By default, we keys found by getting an exact match on their descriptions.
577 bool key_default_cmp(const struct key *key,
578 const struct key_match_data *match_data)
580 return strcmp(key->description, match_data->raw_data) == 0;
584 * Iteration function to consider each key found.
586 static int keyring_search_iterator(const void *object, void *iterator_data)
588 struct keyring_search_context *ctx = iterator_data;
589 const struct key *key = keyring_ptr_to_key(object);
590 unsigned long kflags = READ_ONCE(key->flags);
591 short state = READ_ONCE(key->state);
593 kenter("{%d}", key->serial);
595 /* ignore keys not of this type */
596 if (key->type != ctx->index_key.type) {
597 kleave(" = 0 [!type]");
601 /* skip invalidated, revoked and expired keys */
602 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
603 time64_t expiry = READ_ONCE(key->expiry);
605 if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
606 (1 << KEY_FLAG_REVOKED))) {
607 ctx->result = ERR_PTR(-EKEYREVOKED);
608 kleave(" = %d [invrev]", ctx->skipped_ret);
612 if (expiry && ctx->now >= expiry) {
613 if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
614 ctx->result = ERR_PTR(-EKEYEXPIRED);
615 kleave(" = %d [expire]", ctx->skipped_ret);
620 /* keys that don't match */
621 if (!ctx->match_data.cmp(key, &ctx->match_data)) {
622 kleave(" = 0 [!match]");
626 /* key must have search permissions */
627 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
628 key_task_permission(make_key_ref(key, ctx->possessed),
629 ctx->cred, KEY_NEED_SEARCH) < 0) {
630 ctx->result = ERR_PTR(-EACCES);
631 kleave(" = %d [!perm]", ctx->skipped_ret);
635 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
636 /* we set a different error code if we pass a negative key */
638 ctx->result = ERR_PTR(state);
639 kleave(" = %d [neg]", ctx->skipped_ret);
645 ctx->result = make_key_ref(key, ctx->possessed);
646 kleave(" = 1 [found]");
650 return ctx->skipped_ret;
654 * Search inside a keyring for a key. We can search by walking to it
655 * directly based on its index-key or we can iterate over the entire
656 * tree looking for it, based on the match function.
658 static int search_keyring(struct key *keyring, struct keyring_search_context *ctx)
660 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_DIRECT) {
663 object = assoc_array_find(&keyring->keys,
664 &keyring_assoc_array_ops,
666 return object ? ctx->iterator(object, ctx) : 0;
668 return assoc_array_iterate(&keyring->keys, ctx->iterator, ctx);
672 * Search a tree of keyrings that point to other keyrings up to the maximum
675 static bool search_nested_keyrings(struct key *keyring,
676 struct keyring_search_context *ctx)
680 struct assoc_array_node *node;
682 } stack[KEYRING_SEARCH_MAX_DEPTH];
684 struct assoc_array_shortcut *shortcut;
685 struct assoc_array_node *node;
686 struct assoc_array_ptr *ptr;
690 kenter("{%d},{%s,%s}",
692 ctx->index_key.type->name,
693 ctx->index_key.description);
695 #define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK)
696 BUG_ON((ctx->flags & STATE_CHECKS) == 0 ||
697 (ctx->flags & STATE_CHECKS) == STATE_CHECKS);
699 if (ctx->index_key.description)
700 key_set_index_key(&ctx->index_key);
702 /* Check to see if this top-level keyring is what we are looking for
703 * and whether it is valid or not.
705 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE ||
706 keyring_compare_object(keyring, &ctx->index_key)) {
707 ctx->skipped_ret = 2;
708 switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) {
718 ctx->skipped_ret = 0;
720 /* Start processing a new keyring */
722 kdebug("descend to %d", keyring->serial);
723 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
724 (1 << KEY_FLAG_REVOKED)))
725 goto not_this_keyring;
727 /* Search through the keys in this keyring before its searching its
730 if (search_keyring(keyring, ctx))
733 /* Then manually iterate through the keyrings nested in this one.
735 * Start from the root node of the index tree. Because of the way the
736 * hash function has been set up, keyrings cluster on the leftmost
737 * branch of the root node (root slot 0) or in the root node itself.
738 * Non-keyrings avoid the leftmost branch of the root entirely (root
741 if (!(ctx->flags & KEYRING_SEARCH_RECURSE))
742 goto not_this_keyring;
744 ptr = READ_ONCE(keyring->keys.root);
746 goto not_this_keyring;
748 if (assoc_array_ptr_is_shortcut(ptr)) {
749 /* If the root is a shortcut, either the keyring only contains
750 * keyring pointers (everything clusters behind root slot 0) or
751 * doesn't contain any keyring pointers.
753 shortcut = assoc_array_ptr_to_shortcut(ptr);
754 if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
755 goto not_this_keyring;
757 ptr = READ_ONCE(shortcut->next_node);
758 node = assoc_array_ptr_to_node(ptr);
762 node = assoc_array_ptr_to_node(ptr);
763 ptr = node->slots[0];
764 if (!assoc_array_ptr_is_meta(ptr))
768 /* Descend to a more distal node in this keyring's content tree and go
772 if (assoc_array_ptr_is_shortcut(ptr)) {
773 shortcut = assoc_array_ptr_to_shortcut(ptr);
774 ptr = READ_ONCE(shortcut->next_node);
775 BUG_ON(!assoc_array_ptr_is_node(ptr));
777 node = assoc_array_ptr_to_node(ptr);
780 kdebug("begin_node");
783 /* Go through the slots in a node */
784 for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
785 ptr = READ_ONCE(node->slots[slot]);
787 if (assoc_array_ptr_is_meta(ptr) && node->back_pointer)
788 goto descend_to_node;
790 if (!keyring_ptr_is_keyring(ptr))
793 key = keyring_ptr_to_key(ptr);
795 if (sp >= KEYRING_SEARCH_MAX_DEPTH) {
796 if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) {
797 ctx->result = ERR_PTR(-ELOOP);
800 goto not_this_keyring;
803 /* Search a nested keyring */
804 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
805 key_task_permission(make_key_ref(key, ctx->possessed),
806 ctx->cred, KEY_NEED_SEARCH) < 0)
809 /* stack the current position */
810 stack[sp].keyring = keyring;
811 stack[sp].node = node;
812 stack[sp].slot = slot;
815 /* begin again with the new keyring */
817 goto descend_to_keyring;
820 /* We've dealt with all the slots in the current node, so now we need
821 * to ascend to the parent and continue processing there.
823 ptr = READ_ONCE(node->back_pointer);
824 slot = node->parent_slot;
826 if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
827 shortcut = assoc_array_ptr_to_shortcut(ptr);
828 ptr = READ_ONCE(shortcut->back_pointer);
829 slot = shortcut->parent_slot;
832 goto not_this_keyring;
833 node = assoc_array_ptr_to_node(ptr);
836 /* If we've ascended to the root (zero backpointer), we must have just
837 * finished processing the leftmost branch rather than the root slots -
838 * so there can't be any more keyrings for us to find.
840 if (node->back_pointer) {
841 kdebug("ascend %d", slot);
845 /* The keyring we're looking at was disqualified or didn't contain a
849 kdebug("not_this_keyring %d", sp);
855 /* Resume the processing of a keyring higher up in the tree */
857 keyring = stack[sp].keyring;
858 node = stack[sp].node;
859 slot = stack[sp].slot + 1;
860 kdebug("ascend to %d [%d]", keyring->serial, slot);
863 /* We found a viable match */
865 key = key_ref_to_ptr(ctx->result);
867 if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) {
868 key->last_used_at = ctx->now;
869 keyring->last_used_at = ctx->now;
871 stack[--sp].keyring->last_used_at = ctx->now;
878 * keyring_search_rcu - Search a keyring tree for a matching key under RCU
879 * @keyring_ref: A pointer to the keyring with possession indicator.
880 * @ctx: The keyring search context.
882 * Search the supplied keyring tree for a key that matches the criteria given.
883 * The root keyring and any linked keyrings must grant Search permission to the
884 * caller to be searchable and keys can only be found if they too grant Search
885 * to the caller. The possession flag on the root keyring pointer controls use
886 * of the possessor bits in permissions checking of the entire tree. In
887 * addition, the LSM gets to forbid keyring searches and key matches.
889 * The search is performed as a breadth-then-depth search up to the prescribed
890 * limit (KEYRING_SEARCH_MAX_DEPTH). The caller must hold the RCU read lock to
891 * prevent keyrings from being destroyed or rearranged whilst they are being
894 * Keys are matched to the type provided and are then filtered by the match
895 * function, which is given the description to use in any way it sees fit. The
896 * match function may use any attributes of a key that it wishes to to
897 * determine the match. Normally the match function from the key type would be
900 * RCU can be used to prevent the keyring key lists from disappearing without
901 * the need to take lots of locks.
903 * Returns a pointer to the found key and increments the key usage count if
904 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
905 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
906 * specified keyring wasn't a keyring.
908 * In the case of a successful return, the possession attribute from
909 * @keyring_ref is propagated to the returned key reference.
911 key_ref_t keyring_search_rcu(key_ref_t keyring_ref,
912 struct keyring_search_context *ctx)
917 ctx->iterator = keyring_search_iterator;
918 ctx->possessed = is_key_possessed(keyring_ref);
919 ctx->result = ERR_PTR(-EAGAIN);
921 keyring = key_ref_to_ptr(keyring_ref);
924 if (keyring->type != &key_type_keyring)
925 return ERR_PTR(-ENOTDIR);
927 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) {
928 err = key_task_permission(keyring_ref, ctx->cred, KEY_NEED_SEARCH);
933 ctx->now = ktime_get_real_seconds();
934 if (search_nested_keyrings(keyring, ctx))
935 __key_get(key_ref_to_ptr(ctx->result));
940 * keyring_search - Search the supplied keyring tree for a matching key
941 * @keyring: The root of the keyring tree to be searched.
942 * @type: The type of keyring we want to find.
943 * @description: The name of the keyring we want to find.
944 * @recurse: True to search the children of @keyring also
946 * As keyring_search_rcu() above, but using the current task's credentials and
947 * type's default matching function and preferred search method.
949 key_ref_t keyring_search(key_ref_t keyring,
950 struct key_type *type,
951 const char *description,
954 struct keyring_search_context ctx = {
955 .index_key.type = type,
956 .index_key.description = description,
957 .index_key.desc_len = strlen(description),
958 .cred = current_cred(),
959 .match_data.cmp = key_default_cmp,
960 .match_data.raw_data = description,
961 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
962 .flags = KEYRING_SEARCH_DO_STATE_CHECK,
968 ctx.flags |= KEYRING_SEARCH_RECURSE;
969 if (type->match_preparse) {
970 ret = type->match_preparse(&ctx.match_data);
976 key = keyring_search_rcu(keyring, &ctx);
979 if (type->match_free)
980 type->match_free(&ctx.match_data);
983 EXPORT_SYMBOL(keyring_search);
985 static struct key_restriction *keyring_restriction_alloc(
986 key_restrict_link_func_t check)
988 struct key_restriction *keyres =
989 kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
992 return ERR_PTR(-ENOMEM);
994 keyres->check = check;
1000 * Semaphore to serialise restriction setup to prevent reference count
1001 * cycles through restriction key pointers.
1003 static DECLARE_RWSEM(keyring_serialise_restrict_sem);
1006 * Check for restriction cycles that would prevent keyring garbage collection.
1007 * keyring_serialise_restrict_sem must be held.
1009 static bool keyring_detect_restriction_cycle(const struct key *dest_keyring,
1010 struct key_restriction *keyres)
1012 while (keyres && keyres->key &&
1013 keyres->key->type == &key_type_keyring) {
1014 if (keyres->key == dest_keyring)
1017 keyres = keyres->key->restrict_link;
1024 * keyring_restrict - Look up and apply a restriction to a keyring
1025 * @keyring_ref: The keyring to be restricted
1026 * @type: The key type that will provide the restriction checker.
1027 * @restriction: The restriction options to apply to the keyring
1029 * Look up a keyring and apply a restriction to it. The restriction is managed
1030 * by the specific key type, but can be configured by the options specified in
1031 * the restriction string.
1033 int keyring_restrict(key_ref_t keyring_ref, const char *type,
1034 const char *restriction)
1036 struct key *keyring;
1037 struct key_type *restrict_type = NULL;
1038 struct key_restriction *restrict_link;
1041 keyring = key_ref_to_ptr(keyring_ref);
1044 if (keyring->type != &key_type_keyring)
1048 restrict_link = keyring_restriction_alloc(restrict_link_reject);
1050 restrict_type = key_type_lookup(type);
1052 if (IS_ERR(restrict_type))
1053 return PTR_ERR(restrict_type);
1055 if (!restrict_type->lookup_restriction) {
1060 restrict_link = restrict_type->lookup_restriction(restriction);
1063 if (IS_ERR(restrict_link)) {
1064 ret = PTR_ERR(restrict_link);
1068 down_write(&keyring->sem);
1069 down_write(&keyring_serialise_restrict_sem);
1071 if (keyring->restrict_link)
1073 else if (keyring_detect_restriction_cycle(keyring, restrict_link))
1076 keyring->restrict_link = restrict_link;
1078 up_write(&keyring_serialise_restrict_sem);
1079 up_write(&keyring->sem);
1082 key_put(restrict_link->key);
1083 kfree(restrict_link);
1088 key_type_put(restrict_type);
1092 EXPORT_SYMBOL(keyring_restrict);
1095 * Search the given keyring for a key that might be updated.
1097 * The caller must guarantee that the keyring is a keyring and that the
1098 * permission is granted to modify the keyring as no check is made here. The
1099 * caller must also hold a lock on the keyring semaphore.
1101 * Returns a pointer to the found key with usage count incremented if
1102 * successful and returns NULL if not found. Revoked and invalidated keys are
1105 * If successful, the possession indicator is propagated from the keyring ref
1106 * to the returned key reference.
1108 key_ref_t find_key_to_update(key_ref_t keyring_ref,
1109 const struct keyring_index_key *index_key)
1111 struct key *keyring, *key;
1114 keyring = key_ref_to_ptr(keyring_ref);
1116 kenter("{%d},{%s,%s}",
1117 keyring->serial, index_key->type->name, index_key->description);
1119 object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops,
1129 key = keyring_ptr_to_key(object);
1130 if (key->flags & ((1 << KEY_FLAG_INVALIDATED) |
1131 (1 << KEY_FLAG_REVOKED))) {
1132 kleave(" = NULL [x]");
1136 kleave(" = {%d}", key->serial);
1137 return make_key_ref(key, is_key_possessed(keyring_ref));
1141 * Find a keyring with the specified name.
1143 * Only keyrings that have nonzero refcount, are not revoked, and are owned by
1144 * a user in the current user namespace are considered. If @uid_keyring is
1145 * %true, the keyring additionally must have been allocated as a user or user
1146 * session keyring; otherwise, it must grant JOIN permission directly to the
1147 * caller (ie. not through possession).
1149 * Returns a pointer to the keyring with the keyring's refcount having being
1150 * incremented on success. -ENOKEY is returned if a key could not be found.
1152 struct key *find_keyring_by_name(const char *name, bool uid_keyring)
1154 struct user_namespace *ns = current_user_ns();
1155 struct key *keyring;
1158 return ERR_PTR(-EINVAL);
1160 read_lock(&keyring_name_lock);
1162 /* Search this hash bucket for a keyring with a matching name that
1163 * grants Search permission and that hasn't been revoked
1165 list_for_each_entry(keyring, &ns->keyring_name_list, name_link) {
1166 if (!kuid_has_mapping(ns, keyring->user->uid))
1169 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1172 if (strcmp(keyring->description, name) != 0)
1176 if (!test_bit(KEY_FLAG_UID_KEYRING,
1180 if (key_permission(make_key_ref(keyring, 0),
1185 /* we've got a match but we might end up racing with
1186 * key_cleanup() if the keyring is currently 'dead'
1187 * (ie. it has a zero usage count) */
1188 if (!refcount_inc_not_zero(&keyring->usage))
1190 keyring->last_used_at = ktime_get_real_seconds();
1194 keyring = ERR_PTR(-ENOKEY);
1196 read_unlock(&keyring_name_lock);
1200 static int keyring_detect_cycle_iterator(const void *object,
1201 void *iterator_data)
1203 struct keyring_search_context *ctx = iterator_data;
1204 const struct key *key = keyring_ptr_to_key(object);
1206 kenter("{%d}", key->serial);
1208 /* We might get a keyring with matching index-key that is nonetheless a
1209 * different keyring. */
1210 if (key != ctx->match_data.raw_data)
1213 ctx->result = ERR_PTR(-EDEADLK);
1218 * See if a cycle will will be created by inserting acyclic tree B in acyclic
1219 * tree A at the topmost level (ie: as a direct child of A).
1221 * Since we are adding B to A at the top level, checking for cycles should just
1222 * be a matter of seeing if node A is somewhere in tree B.
1224 static int keyring_detect_cycle(struct key *A, struct key *B)
1226 struct keyring_search_context ctx = {
1227 .index_key = A->index_key,
1228 .match_data.raw_data = A,
1229 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
1230 .iterator = keyring_detect_cycle_iterator,
1231 .flags = (KEYRING_SEARCH_NO_STATE_CHECK |
1232 KEYRING_SEARCH_NO_UPDATE_TIME |
1233 KEYRING_SEARCH_NO_CHECK_PERM |
1234 KEYRING_SEARCH_DETECT_TOO_DEEP |
1235 KEYRING_SEARCH_RECURSE),
1239 search_nested_keyrings(B, &ctx);
1241 return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);
1245 * Lock keyring for link.
1247 int __key_link_lock(struct key *keyring,
1248 const struct keyring_index_key *index_key)
1249 __acquires(&keyring->sem)
1250 __acquires(&keyring_serialise_link_lock)
1252 if (keyring->type != &key_type_keyring)
1255 down_write(&keyring->sem);
1257 /* Serialise link/link calls to prevent parallel calls causing a cycle
1258 * when linking two keyring in opposite orders.
1260 if (index_key->type == &key_type_keyring)
1261 mutex_lock(&keyring_serialise_link_lock);
1267 * Lock keyrings for move (link/unlink combination).
1269 int __key_move_lock(struct key *l_keyring, struct key *u_keyring,
1270 const struct keyring_index_key *index_key)
1271 __acquires(&l_keyring->sem)
1272 __acquires(&u_keyring->sem)
1273 __acquires(&keyring_serialise_link_lock)
1275 if (l_keyring->type != &key_type_keyring ||
1276 u_keyring->type != &key_type_keyring)
1279 /* We have to be very careful here to take the keyring locks in the
1280 * right order, lest we open ourselves to deadlocking against another
1283 if (l_keyring < u_keyring) {
1284 down_write(&l_keyring->sem);
1285 down_write_nested(&u_keyring->sem, 1);
1287 down_write(&u_keyring->sem);
1288 down_write_nested(&l_keyring->sem, 1);
1291 /* Serialise link/link calls to prevent parallel calls causing a cycle
1292 * when linking two keyring in opposite orders.
1294 if (index_key->type == &key_type_keyring)
1295 mutex_lock(&keyring_serialise_link_lock);
1301 * Preallocate memory so that a key can be linked into to a keyring.
1303 int __key_link_begin(struct key *keyring,
1304 const struct keyring_index_key *index_key,
1305 struct assoc_array_edit **_edit)
1307 struct assoc_array_edit *edit;
1311 keyring->serial, index_key->type->name, index_key->description);
1313 BUG_ON(index_key->desc_len == 0);
1314 BUG_ON(*_edit != NULL);
1319 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1322 /* Create an edit script that will insert/replace the key in the
1325 edit = assoc_array_insert(&keyring->keys,
1326 &keyring_assoc_array_ops,
1330 ret = PTR_ERR(edit);
1334 /* If we're not replacing a link in-place then we're going to need some
1337 if (!edit->dead_leaf) {
1338 ret = key_payload_reserve(keyring,
1339 keyring->datalen + KEYQUOTA_LINK_BYTES);
1349 assoc_array_cancel_edit(edit);
1351 kleave(" = %d", ret);
1356 * Check already instantiated keys aren't going to be a problem.
1358 * The caller must have called __key_link_begin(). Don't need to call this for
1359 * keys that were created since __key_link_begin() was called.
1361 int __key_link_check_live_key(struct key *keyring, struct key *key)
1363 if (key->type == &key_type_keyring)
1364 /* check that we aren't going to create a cycle by linking one
1365 * keyring to another */
1366 return keyring_detect_cycle(keyring, key);
1371 * Link a key into to a keyring.
1373 * Must be called with __key_link_begin() having being called. Discards any
1374 * already extant link to matching key if there is one, so that each keyring
1375 * holds at most one link to any given key of a particular type+description
1378 void __key_link(struct key *key, struct assoc_array_edit **_edit)
1381 assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key));
1382 assoc_array_apply_edit(*_edit);
1387 * Finish linking a key into to a keyring.
1389 * Must be called with __key_link_begin() having being called.
1391 void __key_link_end(struct key *keyring,
1392 const struct keyring_index_key *index_key,
1393 struct assoc_array_edit *edit)
1394 __releases(&keyring->sem)
1395 __releases(&keyring_serialise_link_lock)
1397 BUG_ON(index_key->type == NULL);
1398 kenter("%d,%s,", keyring->serial, index_key->type->name);
1401 if (!edit->dead_leaf) {
1402 key_payload_reserve(keyring,
1403 keyring->datalen - KEYQUOTA_LINK_BYTES);
1405 assoc_array_cancel_edit(edit);
1407 up_write(&keyring->sem);
1409 if (index_key->type == &key_type_keyring)
1410 mutex_unlock(&keyring_serialise_link_lock);
1414 * Check addition of keys to restricted keyrings.
1416 static int __key_link_check_restriction(struct key *keyring, struct key *key)
1418 if (!keyring->restrict_link || !keyring->restrict_link->check)
1420 return keyring->restrict_link->check(keyring, key->type, &key->payload,
1421 keyring->restrict_link->key);
1425 * key_link - Link a key to a keyring
1426 * @keyring: The keyring to make the link in.
1427 * @key: The key to link to.
1429 * Make a link in a keyring to a key, such that the keyring holds a reference
1430 * on that key and the key can potentially be found by searching that keyring.
1432 * This function will write-lock the keyring's semaphore and will consume some
1433 * of the user's key data quota to hold the link.
1435 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1436 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1437 * full, -EDQUOT if there is insufficient key data quota remaining to add
1438 * another link or -ENOMEM if there's insufficient memory.
1440 * It is assumed that the caller has checked that it is permitted for a link to
1441 * be made (the keyring should have Write permission and the key Link
1444 int key_link(struct key *keyring, struct key *key)
1446 struct assoc_array_edit *edit = NULL;
1449 kenter("{%d,%d}", keyring->serial, refcount_read(&keyring->usage));
1454 ret = __key_link_lock(keyring, &key->index_key);
1458 ret = __key_link_begin(keyring, &key->index_key, &edit);
1462 kdebug("begun {%d,%d}", keyring->serial, refcount_read(&keyring->usage));
1463 ret = __key_link_check_restriction(keyring, key);
1465 ret = __key_link_check_live_key(keyring, key);
1467 __key_link(key, &edit);
1470 __key_link_end(keyring, &key->index_key, edit);
1472 kleave(" = %d {%d,%d}", ret, keyring->serial, refcount_read(&keyring->usage));
1475 EXPORT_SYMBOL(key_link);
1478 * Lock a keyring for unlink.
1480 static int __key_unlink_lock(struct key *keyring)
1481 __acquires(&keyring->sem)
1483 if (keyring->type != &key_type_keyring)
1486 down_write(&keyring->sem);
1491 * Begin the process of unlinking a key from a keyring.
1493 static int __key_unlink_begin(struct key *keyring, struct key *key,
1494 struct assoc_array_edit **_edit)
1496 struct assoc_array_edit *edit;
1498 BUG_ON(*_edit != NULL);
1500 edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
1503 return PTR_ERR(edit);
1513 * Apply an unlink change.
1515 static void __key_unlink(struct key *keyring, struct key *key,
1516 struct assoc_array_edit **_edit)
1518 assoc_array_apply_edit(*_edit);
1520 key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
1524 * Finish unlinking a key from to a keyring.
1526 static void __key_unlink_end(struct key *keyring,
1528 struct assoc_array_edit *edit)
1529 __releases(&keyring->sem)
1532 assoc_array_cancel_edit(edit);
1533 up_write(&keyring->sem);
1537 * key_unlink - Unlink the first link to a key from a keyring.
1538 * @keyring: The keyring to remove the link from.
1539 * @key: The key the link is to.
1541 * Remove a link from a keyring to a key.
1543 * This function will write-lock the keyring's semaphore.
1545 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1546 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1549 * It is assumed that the caller has checked that it is permitted for a link to
1550 * be removed (the keyring should have Write permission; no permissions are
1551 * required on the key).
1553 int key_unlink(struct key *keyring, struct key *key)
1555 struct assoc_array_edit *edit = NULL;
1561 ret = __key_unlink_lock(keyring);
1565 ret = __key_unlink_begin(keyring, key, &edit);
1567 __key_unlink(keyring, key, &edit);
1568 __key_unlink_end(keyring, key, edit);
1571 EXPORT_SYMBOL(key_unlink);
1574 * key_move - Move a key from one keyring to another
1575 * @key: The key to move
1576 * @from_keyring: The keyring to remove the link from.
1577 * @to_keyring: The keyring to make the link in.
1578 * @flags: Qualifying flags, such as KEYCTL_MOVE_EXCL.
1580 * Make a link in @to_keyring to a key, such that the keyring holds a reference
1581 * on that key and the key can potentially be found by searching that keyring
1582 * whilst simultaneously removing a link to the key from @from_keyring.
1584 * This function will write-lock both keyring's semaphores and will consume
1585 * some of the user's key data quota to hold the link on @to_keyring.
1587 * Returns 0 if successful, -ENOTDIR if either keyring isn't a keyring,
1588 * -EKEYREVOKED if either keyring has been revoked, -ENFILE if the second
1589 * keyring is full, -EDQUOT if there is insufficient key data quota remaining
1590 * to add another link or -ENOMEM if there's insufficient memory. If
1591 * KEYCTL_MOVE_EXCL is set, then -EEXIST will be returned if there's already a
1592 * matching key in @to_keyring.
1594 * It is assumed that the caller has checked that it is permitted for a link to
1595 * be made (the keyring should have Write permission and the key Link
1598 int key_move(struct key *key,
1599 struct key *from_keyring,
1600 struct key *to_keyring,
1603 struct assoc_array_edit *from_edit = NULL, *to_edit = NULL;
1606 kenter("%d,%d,%d", key->serial, from_keyring->serial, to_keyring->serial);
1608 if (from_keyring == to_keyring)
1612 key_check(from_keyring);
1613 key_check(to_keyring);
1615 ret = __key_move_lock(from_keyring, to_keyring, &key->index_key);
1618 ret = __key_unlink_begin(from_keyring, key, &from_edit);
1621 ret = __key_link_begin(to_keyring, &key->index_key, &to_edit);
1626 if (to_edit->dead_leaf && (flags & KEYCTL_MOVE_EXCL))
1629 ret = __key_link_check_restriction(to_keyring, key);
1632 ret = __key_link_check_live_key(to_keyring, key);
1636 __key_unlink(from_keyring, key, &from_edit);
1637 __key_link(key, &to_edit);
1639 __key_link_end(to_keyring, &key->index_key, to_edit);
1640 __key_unlink_end(from_keyring, key, from_edit);
1642 kleave(" = %d", ret);
1645 EXPORT_SYMBOL(key_move);
1648 * keyring_clear - Clear a keyring
1649 * @keyring: The keyring to clear.
1651 * Clear the contents of the specified keyring.
1653 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1655 int keyring_clear(struct key *keyring)
1657 struct assoc_array_edit *edit;
1660 if (keyring->type != &key_type_keyring)
1663 down_write(&keyring->sem);
1665 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1667 ret = PTR_ERR(edit);
1670 assoc_array_apply_edit(edit);
1671 key_payload_reserve(keyring, 0);
1675 up_write(&keyring->sem);
1678 EXPORT_SYMBOL(keyring_clear);
1681 * Dispose of the links from a revoked keyring.
1683 * This is called with the key sem write-locked.
1685 static void keyring_revoke(struct key *keyring)
1687 struct assoc_array_edit *edit;
1689 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1690 if (!IS_ERR(edit)) {
1692 assoc_array_apply_edit(edit);
1693 key_payload_reserve(keyring, 0);
1697 static bool keyring_gc_select_iterator(void *object, void *iterator_data)
1699 struct key *key = keyring_ptr_to_key(object);
1700 time64_t *limit = iterator_data;
1702 if (key_is_dead(key, *limit))
1708 static int keyring_gc_check_iterator(const void *object, void *iterator_data)
1710 const struct key *key = keyring_ptr_to_key(object);
1711 time64_t *limit = iterator_data;
1714 return key_is_dead(key, *limit);
1718 * Garbage collect pointers from a keyring.
1720 * Not called with any locks held. The keyring's key struct will not be
1721 * deallocated under us as only our caller may deallocate it.
1723 void keyring_gc(struct key *keyring, time64_t limit)
1727 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1729 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
1730 (1 << KEY_FLAG_REVOKED)))
1733 /* scan the keyring looking for dead keys */
1735 result = assoc_array_iterate(&keyring->keys,
1736 keyring_gc_check_iterator, &limit);
1746 down_write(&keyring->sem);
1747 assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops,
1748 keyring_gc_select_iterator, &limit);
1749 up_write(&keyring->sem);
1754 * Garbage collect restriction pointers from a keyring.
1756 * Keyring restrictions are associated with a key type, and must be cleaned
1757 * up if the key type is unregistered. The restriction is altered to always
1758 * reject additional keys so a keyring cannot be opened up by unregistering
1761 * Not called with any keyring locks held. The keyring's key struct will not
1762 * be deallocated under us as only our caller may deallocate it.
1764 * The caller is required to hold key_types_sem and dead_type->sem. This is
1765 * fulfilled by key_gc_keytype() holding the locks on behalf of
1766 * key_garbage_collector(), which it invokes on a workqueue.
1768 void keyring_restriction_gc(struct key *keyring, struct key_type *dead_type)
1770 struct key_restriction *keyres;
1772 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1775 * keyring->restrict_link is only assigned at key allocation time
1776 * or with the key type locked, so the only values that could be
1777 * concurrently assigned to keyring->restrict_link are for key
1778 * types other than dead_type. Given this, it's ok to check
1779 * the key type before acquiring keyring->sem.
1781 if (!dead_type || !keyring->restrict_link ||
1782 keyring->restrict_link->keytype != dead_type) {
1783 kleave(" [no restriction gc]");
1787 /* Lock the keyring to ensure that a link is not in progress */
1788 down_write(&keyring->sem);
1790 keyres = keyring->restrict_link;
1792 keyres->check = restrict_link_reject;
1794 key_put(keyres->key);
1796 keyres->keytype = NULL;
1798 up_write(&keyring->sem);
1800 kleave(" [restriction gc]");