3 * Copyright (C) 2004-2005, 2008, 2013 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/export.h>
13 #include <linux/init.h>
14 #include <linux/sched.h>
15 #include <linux/slab.h>
16 #include <linux/security.h>
17 #include <linux/seq_file.h>
18 #include <linux/err.h>
19 #include <keys/keyring-type.h>
20 #include <keys/user-type.h>
21 #include <linux/assoc_array_priv.h>
22 #include <linux/uaccess.h>
26 * When plumbing the depths of the key tree, this sets a hard limit
27 * set on how deep we're willing to go.
29 #define KEYRING_SEARCH_MAX_DEPTH 6
32 * We keep all named keyrings in a hash to speed looking them up.
34 #define KEYRING_NAME_HASH_SIZE (1 << 5)
37 * We mark pointers we pass to the associative array with bit 1 set if
38 * they're keyrings and clear otherwise.
40 #define KEYRING_PTR_SUBTYPE 0x2UL
42 static inline bool keyring_ptr_is_keyring(const struct assoc_array_ptr *x)
44 return (unsigned long)x & KEYRING_PTR_SUBTYPE;
46 static inline struct key *keyring_ptr_to_key(const struct assoc_array_ptr *x)
48 void *object = assoc_array_ptr_to_leaf(x);
49 return (struct key *)((unsigned long)object & ~KEYRING_PTR_SUBTYPE);
51 static inline void *keyring_key_to_ptr(struct key *key)
53 if (key->type == &key_type_keyring)
54 return (void *)((unsigned long)key | KEYRING_PTR_SUBTYPE);
58 static struct list_head keyring_name_hash[KEYRING_NAME_HASH_SIZE];
59 static DEFINE_RWLOCK(keyring_name_lock);
61 static inline unsigned keyring_hash(const char *desc)
66 bucket += (unsigned char)*desc;
68 return bucket & (KEYRING_NAME_HASH_SIZE - 1);
72 * The keyring key type definition. Keyrings are simply keys of this type and
73 * can be treated as ordinary keys in addition to having their own special
76 static int keyring_preparse(struct key_preparsed_payload *prep);
77 static void keyring_free_preparse(struct key_preparsed_payload *prep);
78 static int keyring_instantiate(struct key *keyring,
79 struct key_preparsed_payload *prep);
80 static void keyring_revoke(struct key *keyring);
81 static void keyring_destroy(struct key *keyring);
82 static void keyring_describe(const struct key *keyring, struct seq_file *m);
83 static long keyring_read(const struct key *keyring,
84 char __user *buffer, size_t buflen);
86 struct key_type key_type_keyring = {
89 .preparse = keyring_preparse,
90 .free_preparse = keyring_free_preparse,
91 .instantiate = keyring_instantiate,
92 .revoke = keyring_revoke,
93 .destroy = keyring_destroy,
94 .describe = keyring_describe,
97 EXPORT_SYMBOL(key_type_keyring);
100 * Semaphore to serialise link/link calls to prevent two link calls in parallel
101 * introducing a cycle.
103 static DECLARE_RWSEM(keyring_serialise_link_sem);
106 * Publish the name of a keyring so that it can be found by name (if it has
109 static void keyring_publish_name(struct key *keyring)
113 if (keyring->description) {
114 bucket = keyring_hash(keyring->description);
116 write_lock(&keyring_name_lock);
118 if (!keyring_name_hash[bucket].next)
119 INIT_LIST_HEAD(&keyring_name_hash[bucket]);
121 list_add_tail(&keyring->name_link,
122 &keyring_name_hash[bucket]);
124 write_unlock(&keyring_name_lock);
129 * Preparse a keyring payload
131 static int keyring_preparse(struct key_preparsed_payload *prep)
133 return prep->datalen != 0 ? -EINVAL : 0;
137 * Free a preparse of a user defined key payload
139 static void keyring_free_preparse(struct key_preparsed_payload *prep)
144 * Initialise a keyring.
146 * Returns 0 on success, -EINVAL if given any data.
148 static int keyring_instantiate(struct key *keyring,
149 struct key_preparsed_payload *prep)
151 assoc_array_init(&keyring->keys);
152 /* make the keyring available by name if it has one */
153 keyring_publish_name(keyring);
158 * Multiply 64-bits by 32-bits to 96-bits and fold back to 64-bit. Ideally we'd
159 * fold the carry back too, but that requires inline asm.
161 static u64 mult_64x32_and_fold(u64 x, u32 y)
163 u64 hi = (u64)(u32)(x >> 32) * y;
164 u64 lo = (u64)(u32)(x) * y;
165 return lo + ((u64)(u32)hi << 32) + (u32)(hi >> 32);
169 * Hash a key type and description.
171 static unsigned long hash_key_type_and_desc(const struct keyring_index_key *index_key)
173 const unsigned level_shift = ASSOC_ARRAY_LEVEL_STEP;
174 const unsigned long fan_mask = ASSOC_ARRAY_FAN_MASK;
175 const char *description = index_key->description;
176 unsigned long hash, type;
179 int n, desc_len = index_key->desc_len;
181 type = (unsigned long)index_key->type;
183 acc = mult_64x32_and_fold(type, desc_len + 13);
184 acc = mult_64x32_and_fold(acc, 9207);
192 memcpy(&piece, description, n);
195 acc = mult_64x32_and_fold(acc, piece);
196 acc = mult_64x32_and_fold(acc, 9207);
199 /* Fold the hash down to 32 bits if need be. */
201 if (ASSOC_ARRAY_KEY_CHUNK_SIZE == 32)
204 /* Squidge all the keyrings into a separate part of the tree to
205 * ordinary keys by making sure the lowest level segment in the hash is
206 * zero for keyrings and non-zero otherwise.
208 if (index_key->type != &key_type_keyring && (hash & fan_mask) == 0)
209 return hash | (hash >> (ASSOC_ARRAY_KEY_CHUNK_SIZE - level_shift)) | 1;
210 if (index_key->type == &key_type_keyring && (hash & fan_mask) != 0)
211 return (hash + (hash << level_shift)) & ~fan_mask;
216 * Build the next index key chunk.
218 * On 32-bit systems the index key is laid out as:
221 * hash desclen typeptr desc[]
226 * hash desclen typeptr desc[]
228 * We return it one word-sized chunk at a time.
230 static unsigned long keyring_get_key_chunk(const void *data, int level)
232 const struct keyring_index_key *index_key = data;
233 unsigned long chunk = 0;
235 int desc_len = index_key->desc_len, n = sizeof(chunk);
237 level /= ASSOC_ARRAY_KEY_CHUNK_SIZE;
240 return hash_key_type_and_desc(index_key);
242 return ((unsigned long)index_key->type << 8) | desc_len;
245 return (u8)((unsigned long)index_key->type >>
246 (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
251 offset += sizeof(chunk) - 1;
252 offset += (level - 3) * sizeof(chunk);
253 if (offset >= desc_len)
261 chunk |= ((u8*)index_key->description)[--offset];
262 } while (--desc_len > 0);
266 chunk |= (u8)((unsigned long)index_key->type >>
267 (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
273 static unsigned long keyring_get_object_key_chunk(const void *object, int level)
275 const struct key *key = keyring_ptr_to_key(object);
276 return keyring_get_key_chunk(&key->index_key, level);
279 static bool keyring_compare_object(const void *object, const void *data)
281 const struct keyring_index_key *index_key = data;
282 const struct key *key = keyring_ptr_to_key(object);
284 return key->index_key.type == index_key->type &&
285 key->index_key.desc_len == index_key->desc_len &&
286 memcmp(key->index_key.description, index_key->description,
287 index_key->desc_len) == 0;
291 * Compare the index keys of a pair of objects and determine the bit position
292 * at which they differ - if they differ.
294 static int keyring_diff_objects(const void *object, const void *data)
296 const struct key *key_a = keyring_ptr_to_key(object);
297 const struct keyring_index_key *a = &key_a->index_key;
298 const struct keyring_index_key *b = data;
299 unsigned long seg_a, seg_b;
303 seg_a = hash_key_type_and_desc(a);
304 seg_b = hash_key_type_and_desc(b);
305 if ((seg_a ^ seg_b) != 0)
308 /* The number of bits contributed by the hash is controlled by a
309 * constant in the assoc_array headers. Everything else thereafter we
310 * can deal with as being machine word-size dependent.
312 level += ASSOC_ARRAY_KEY_CHUNK_SIZE / 8;
315 if ((seg_a ^ seg_b) != 0)
318 /* The next bit may not work on big endian */
320 seg_a = (unsigned long)a->type;
321 seg_b = (unsigned long)b->type;
322 if ((seg_a ^ seg_b) != 0)
325 level += sizeof(unsigned long);
326 if (a->desc_len == 0)
330 if (((unsigned long)a->description | (unsigned long)b->description) &
331 (sizeof(unsigned long) - 1)) {
333 seg_a = *(unsigned long *)(a->description + i);
334 seg_b = *(unsigned long *)(b->description + i);
335 if ((seg_a ^ seg_b) != 0)
337 i += sizeof(unsigned long);
338 } while (i < (a->desc_len & (sizeof(unsigned long) - 1)));
341 for (; i < a->desc_len; i++) {
342 seg_a = *(unsigned char *)(a->description + i);
343 seg_b = *(unsigned char *)(b->description + i);
344 if ((seg_a ^ seg_b) != 0)
354 i = level * 8 + __ffs(seg_a ^ seg_b);
359 * Free an object after stripping the keyring flag off of the pointer.
361 static void keyring_free_object(void *object)
363 key_put(keyring_ptr_to_key(object));
367 * Operations for keyring management by the index-tree routines.
369 static const struct assoc_array_ops keyring_assoc_array_ops = {
370 .get_key_chunk = keyring_get_key_chunk,
371 .get_object_key_chunk = keyring_get_object_key_chunk,
372 .compare_object = keyring_compare_object,
373 .diff_objects = keyring_diff_objects,
374 .free_object = keyring_free_object,
378 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
379 * and dispose of its data.
381 * The garbage collector detects the final key_put(), removes the keyring from
382 * the serial number tree and then does RCU synchronisation before coming here,
383 * so we shouldn't need to worry about code poking around here with the RCU
384 * readlock held by this time.
386 static void keyring_destroy(struct key *keyring)
388 if (keyring->description) {
389 write_lock(&keyring_name_lock);
391 if (keyring->name_link.next != NULL &&
392 !list_empty(&keyring->name_link))
393 list_del(&keyring->name_link);
395 write_unlock(&keyring_name_lock);
398 if (keyring->restrict_link) {
399 struct key_restriction *keyres = keyring->restrict_link;
401 key_put(keyres->key);
405 assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops);
409 * Describe a keyring for /proc.
411 static void keyring_describe(const struct key *keyring, struct seq_file *m)
413 if (keyring->description)
414 seq_puts(m, keyring->description);
416 seq_puts(m, "[anon]");
418 if (key_is_positive(keyring)) {
419 if (keyring->keys.nr_leaves_on_tree != 0)
420 seq_printf(m, ": %lu", keyring->keys.nr_leaves_on_tree);
422 seq_puts(m, ": empty");
426 struct keyring_read_iterator_context {
429 key_serial_t __user *buffer;
432 static int keyring_read_iterator(const void *object, void *data)
434 struct keyring_read_iterator_context *ctx = data;
435 const struct key *key = keyring_ptr_to_key(object);
438 kenter("{%s,%d},,{%zu/%zu}",
439 key->type->name, key->serial, ctx->count, ctx->buflen);
441 if (ctx->count >= ctx->buflen)
444 ret = put_user(key->serial, ctx->buffer);
448 ctx->count += sizeof(key->serial);
453 * Read a list of key IDs from the keyring's contents in binary form
455 * The keyring's semaphore is read-locked by the caller. This prevents someone
456 * from modifying it under us - which could cause us to read key IDs multiple
459 static long keyring_read(const struct key *keyring,
460 char __user *buffer, size_t buflen)
462 struct keyring_read_iterator_context ctx;
465 kenter("{%d},,%zu", key_serial(keyring), buflen);
467 if (buflen & (sizeof(key_serial_t) - 1))
470 /* Copy as many key IDs as fit into the buffer */
471 if (buffer && buflen) {
472 ctx.buffer = (key_serial_t __user *)buffer;
475 ret = assoc_array_iterate(&keyring->keys,
476 keyring_read_iterator, &ctx);
478 kleave(" = %ld [iterate]", ret);
483 /* Return the size of the buffer needed */
484 ret = keyring->keys.nr_leaves_on_tree * sizeof(key_serial_t);
486 kleave("= %ld [ok]", ret);
488 kleave("= %ld [buffer too small]", ret);
493 * Allocate a keyring and link into the destination keyring.
495 struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
496 const struct cred *cred, key_perm_t perm,
498 struct key_restriction *restrict_link,
504 keyring = key_alloc(&key_type_keyring, description,
505 uid, gid, cred, perm, flags, restrict_link);
506 if (!IS_ERR(keyring)) {
507 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
510 keyring = ERR_PTR(ret);
516 EXPORT_SYMBOL(keyring_alloc);
519 * restrict_link_reject - Give -EPERM to restrict link
520 * @keyring: The keyring being added to.
521 * @type: The type of key being added.
522 * @payload: The payload of the key intended to be added.
523 * @data: Additional data for evaluating restriction.
525 * Reject the addition of any links to a keyring. It can be overridden by
526 * passing KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when
527 * adding a key to a keyring.
529 * This is meant to be stored in a key_restriction structure which is passed
530 * in the restrict_link parameter to keyring_alloc().
532 int restrict_link_reject(struct key *keyring,
533 const struct key_type *type,
534 const union key_payload *payload,
535 struct key *restriction_key)
541 * By default, we keys found by getting an exact match on their descriptions.
543 bool key_default_cmp(const struct key *key,
544 const struct key_match_data *match_data)
546 return strcmp(key->description, match_data->raw_data) == 0;
550 * Iteration function to consider each key found.
552 static int keyring_search_iterator(const void *object, void *iterator_data)
554 struct keyring_search_context *ctx = iterator_data;
555 const struct key *key = keyring_ptr_to_key(object);
556 unsigned long kflags = READ_ONCE(key->flags);
557 short state = READ_ONCE(key->state);
559 kenter("{%d}", key->serial);
561 /* ignore keys not of this type */
562 if (key->type != ctx->index_key.type) {
563 kleave(" = 0 [!type]");
567 /* skip invalidated, revoked and expired keys */
568 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
569 time64_t expiry = READ_ONCE(key->expiry);
571 if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
572 (1 << KEY_FLAG_REVOKED))) {
573 ctx->result = ERR_PTR(-EKEYREVOKED);
574 kleave(" = %d [invrev]", ctx->skipped_ret);
578 if (expiry && ctx->now >= expiry) {
579 if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
580 ctx->result = ERR_PTR(-EKEYEXPIRED);
581 kleave(" = %d [expire]", ctx->skipped_ret);
586 /* keys that don't match */
587 if (!ctx->match_data.cmp(key, &ctx->match_data)) {
588 kleave(" = 0 [!match]");
592 /* key must have search permissions */
593 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
594 key_task_permission(make_key_ref(key, ctx->possessed),
595 ctx->cred, KEY_NEED_SEARCH) < 0) {
596 ctx->result = ERR_PTR(-EACCES);
597 kleave(" = %d [!perm]", ctx->skipped_ret);
601 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
602 /* we set a different error code if we pass a negative key */
604 ctx->result = ERR_PTR(state);
605 kleave(" = %d [neg]", ctx->skipped_ret);
611 ctx->result = make_key_ref(key, ctx->possessed);
612 kleave(" = 1 [found]");
616 return ctx->skipped_ret;
620 * Search inside a keyring for a key. We can search by walking to it
621 * directly based on its index-key or we can iterate over the entire
622 * tree looking for it, based on the match function.
624 static int search_keyring(struct key *keyring, struct keyring_search_context *ctx)
626 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_DIRECT) {
629 object = assoc_array_find(&keyring->keys,
630 &keyring_assoc_array_ops,
632 return object ? ctx->iterator(object, ctx) : 0;
634 return assoc_array_iterate(&keyring->keys, ctx->iterator, ctx);
638 * Search a tree of keyrings that point to other keyrings up to the maximum
641 static bool search_nested_keyrings(struct key *keyring,
642 struct keyring_search_context *ctx)
646 struct assoc_array_node *node;
648 } stack[KEYRING_SEARCH_MAX_DEPTH];
650 struct assoc_array_shortcut *shortcut;
651 struct assoc_array_node *node;
652 struct assoc_array_ptr *ptr;
656 kenter("{%d},{%s,%s}",
658 ctx->index_key.type->name,
659 ctx->index_key.description);
661 #define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK)
662 BUG_ON((ctx->flags & STATE_CHECKS) == 0 ||
663 (ctx->flags & STATE_CHECKS) == STATE_CHECKS);
665 /* Check to see if this top-level keyring is what we are looking for
666 * and whether it is valid or not.
668 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE ||
669 keyring_compare_object(keyring, &ctx->index_key)) {
670 ctx->skipped_ret = 2;
671 switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) {
681 ctx->skipped_ret = 0;
683 /* Start processing a new keyring */
685 kdebug("descend to %d", keyring->serial);
686 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
687 (1 << KEY_FLAG_REVOKED)))
688 goto not_this_keyring;
690 /* Search through the keys in this keyring before its searching its
693 if (search_keyring(keyring, ctx))
696 /* Then manually iterate through the keyrings nested in this one.
698 * Start from the root node of the index tree. Because of the way the
699 * hash function has been set up, keyrings cluster on the leftmost
700 * branch of the root node (root slot 0) or in the root node itself.
701 * Non-keyrings avoid the leftmost branch of the root entirely (root
704 ptr = READ_ONCE(keyring->keys.root);
706 goto not_this_keyring;
708 if (assoc_array_ptr_is_shortcut(ptr)) {
709 /* If the root is a shortcut, either the keyring only contains
710 * keyring pointers (everything clusters behind root slot 0) or
711 * doesn't contain any keyring pointers.
713 shortcut = assoc_array_ptr_to_shortcut(ptr);
714 if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
715 goto not_this_keyring;
717 ptr = READ_ONCE(shortcut->next_node);
718 node = assoc_array_ptr_to_node(ptr);
722 node = assoc_array_ptr_to_node(ptr);
723 ptr = node->slots[0];
724 if (!assoc_array_ptr_is_meta(ptr))
728 /* Descend to a more distal node in this keyring's content tree and go
732 if (assoc_array_ptr_is_shortcut(ptr)) {
733 shortcut = assoc_array_ptr_to_shortcut(ptr);
734 ptr = READ_ONCE(shortcut->next_node);
735 BUG_ON(!assoc_array_ptr_is_node(ptr));
737 node = assoc_array_ptr_to_node(ptr);
740 kdebug("begin_node");
743 /* Go through the slots in a node */
744 for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
745 ptr = READ_ONCE(node->slots[slot]);
747 if (assoc_array_ptr_is_meta(ptr) && node->back_pointer)
748 goto descend_to_node;
750 if (!keyring_ptr_is_keyring(ptr))
753 key = keyring_ptr_to_key(ptr);
755 if (sp >= KEYRING_SEARCH_MAX_DEPTH) {
756 if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) {
757 ctx->result = ERR_PTR(-ELOOP);
760 goto not_this_keyring;
763 /* Search a nested keyring */
764 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
765 key_task_permission(make_key_ref(key, ctx->possessed),
766 ctx->cred, KEY_NEED_SEARCH) < 0)
769 /* stack the current position */
770 stack[sp].keyring = keyring;
771 stack[sp].node = node;
772 stack[sp].slot = slot;
775 /* begin again with the new keyring */
777 goto descend_to_keyring;
780 /* We've dealt with all the slots in the current node, so now we need
781 * to ascend to the parent and continue processing there.
783 ptr = READ_ONCE(node->back_pointer);
784 slot = node->parent_slot;
786 if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
787 shortcut = assoc_array_ptr_to_shortcut(ptr);
788 ptr = READ_ONCE(shortcut->back_pointer);
789 slot = shortcut->parent_slot;
792 goto not_this_keyring;
793 node = assoc_array_ptr_to_node(ptr);
796 /* If we've ascended to the root (zero backpointer), we must have just
797 * finished processing the leftmost branch rather than the root slots -
798 * so there can't be any more keyrings for us to find.
800 if (node->back_pointer) {
801 kdebug("ascend %d", slot);
805 /* The keyring we're looking at was disqualified or didn't contain a
809 kdebug("not_this_keyring %d", sp);
815 /* Resume the processing of a keyring higher up in the tree */
817 keyring = stack[sp].keyring;
818 node = stack[sp].node;
819 slot = stack[sp].slot + 1;
820 kdebug("ascend to %d [%d]", keyring->serial, slot);
823 /* We found a viable match */
825 key = key_ref_to_ptr(ctx->result);
827 if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) {
828 key->last_used_at = ctx->now;
829 keyring->last_used_at = ctx->now;
831 stack[--sp].keyring->last_used_at = ctx->now;
838 * keyring_search_aux - Search a keyring tree for a key matching some criteria
839 * @keyring_ref: A pointer to the keyring with possession indicator.
840 * @ctx: The keyring search context.
842 * Search the supplied keyring tree for a key that matches the criteria given.
843 * The root keyring and any linked keyrings must grant Search permission to the
844 * caller to be searchable and keys can only be found if they too grant Search
845 * to the caller. The possession flag on the root keyring pointer controls use
846 * of the possessor bits in permissions checking of the entire tree. In
847 * addition, the LSM gets to forbid keyring searches and key matches.
849 * The search is performed as a breadth-then-depth search up to the prescribed
850 * limit (KEYRING_SEARCH_MAX_DEPTH).
852 * Keys are matched to the type provided and are then filtered by the match
853 * function, which is given the description to use in any way it sees fit. The
854 * match function may use any attributes of a key that it wishes to to
855 * determine the match. Normally the match function from the key type would be
858 * RCU can be used to prevent the keyring key lists from disappearing without
859 * the need to take lots of locks.
861 * Returns a pointer to the found key and increments the key usage count if
862 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
863 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
864 * specified keyring wasn't a keyring.
866 * In the case of a successful return, the possession attribute from
867 * @keyring_ref is propagated to the returned key reference.
869 key_ref_t keyring_search_aux(key_ref_t keyring_ref,
870 struct keyring_search_context *ctx)
875 ctx->iterator = keyring_search_iterator;
876 ctx->possessed = is_key_possessed(keyring_ref);
877 ctx->result = ERR_PTR(-EAGAIN);
879 keyring = key_ref_to_ptr(keyring_ref);
882 if (keyring->type != &key_type_keyring)
883 return ERR_PTR(-ENOTDIR);
885 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) {
886 err = key_task_permission(keyring_ref, ctx->cred, KEY_NEED_SEARCH);
892 ctx->now = ktime_get_real_seconds();
893 if (search_nested_keyrings(keyring, ctx))
894 __key_get(key_ref_to_ptr(ctx->result));
900 * keyring_search - Search the supplied keyring tree for a matching key
901 * @keyring: The root of the keyring tree to be searched.
902 * @type: The type of keyring we want to find.
903 * @description: The name of the keyring we want to find.
905 * As keyring_search_aux() above, but using the current task's credentials and
906 * type's default matching function and preferred search method.
908 key_ref_t keyring_search(key_ref_t keyring,
909 struct key_type *type,
910 const char *description)
912 struct keyring_search_context ctx = {
913 .index_key.type = type,
914 .index_key.description = description,
915 .index_key.desc_len = strlen(description),
916 .cred = current_cred(),
917 .match_data.cmp = key_default_cmp,
918 .match_data.raw_data = description,
919 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
920 .flags = KEYRING_SEARCH_DO_STATE_CHECK,
925 if (type->match_preparse) {
926 ret = type->match_preparse(&ctx.match_data);
931 key = keyring_search_aux(keyring, &ctx);
933 if (type->match_free)
934 type->match_free(&ctx.match_data);
937 EXPORT_SYMBOL(keyring_search);
939 static struct key_restriction *keyring_restriction_alloc(
940 key_restrict_link_func_t check)
942 struct key_restriction *keyres =
943 kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
946 return ERR_PTR(-ENOMEM);
948 keyres->check = check;
954 * Semaphore to serialise restriction setup to prevent reference count
955 * cycles through restriction key pointers.
957 static DECLARE_RWSEM(keyring_serialise_restrict_sem);
960 * Check for restriction cycles that would prevent keyring garbage collection.
961 * keyring_serialise_restrict_sem must be held.
963 static bool keyring_detect_restriction_cycle(const struct key *dest_keyring,
964 struct key_restriction *keyres)
966 while (keyres && keyres->key &&
967 keyres->key->type == &key_type_keyring) {
968 if (keyres->key == dest_keyring)
971 keyres = keyres->key->restrict_link;
978 * keyring_restrict - Look up and apply a restriction to a keyring
980 * @keyring: The keyring to be restricted
981 * @restriction: The restriction options to apply to the keyring
983 int keyring_restrict(key_ref_t keyring_ref, const char *type,
984 const char *restriction)
987 struct key_type *restrict_type = NULL;
988 struct key_restriction *restrict_link;
991 keyring = key_ref_to_ptr(keyring_ref);
994 if (keyring->type != &key_type_keyring)
998 restrict_link = keyring_restriction_alloc(restrict_link_reject);
1000 restrict_type = key_type_lookup(type);
1002 if (IS_ERR(restrict_type))
1003 return PTR_ERR(restrict_type);
1005 if (!restrict_type->lookup_restriction) {
1010 restrict_link = restrict_type->lookup_restriction(restriction);
1013 if (IS_ERR(restrict_link)) {
1014 ret = PTR_ERR(restrict_link);
1018 down_write(&keyring->sem);
1019 down_write(&keyring_serialise_restrict_sem);
1021 if (keyring->restrict_link)
1023 else if (keyring_detect_restriction_cycle(keyring, restrict_link))
1026 keyring->restrict_link = restrict_link;
1028 up_write(&keyring_serialise_restrict_sem);
1029 up_write(&keyring->sem);
1032 key_put(restrict_link->key);
1033 kfree(restrict_link);
1038 key_type_put(restrict_type);
1042 EXPORT_SYMBOL(keyring_restrict);
1045 * Search the given keyring for a key that might be updated.
1047 * The caller must guarantee that the keyring is a keyring and that the
1048 * permission is granted to modify the keyring as no check is made here. The
1049 * caller must also hold a lock on the keyring semaphore.
1051 * Returns a pointer to the found key with usage count incremented if
1052 * successful and returns NULL if not found. Revoked and invalidated keys are
1055 * If successful, the possession indicator is propagated from the keyring ref
1056 * to the returned key reference.
1058 key_ref_t find_key_to_update(key_ref_t keyring_ref,
1059 const struct keyring_index_key *index_key)
1061 struct key *keyring, *key;
1064 keyring = key_ref_to_ptr(keyring_ref);
1066 kenter("{%d},{%s,%s}",
1067 keyring->serial, index_key->type->name, index_key->description);
1069 object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops,
1079 key = keyring_ptr_to_key(object);
1080 if (key->flags & ((1 << KEY_FLAG_INVALIDATED) |
1081 (1 << KEY_FLAG_REVOKED))) {
1082 kleave(" = NULL [x]");
1086 kleave(" = {%d}", key->serial);
1087 return make_key_ref(key, is_key_possessed(keyring_ref));
1091 * Find a keyring with the specified name.
1093 * Only keyrings that have nonzero refcount, are not revoked, and are owned by a
1094 * user in the current user namespace are considered. If @uid_keyring is %true,
1095 * the keyring additionally must have been allocated as a user or user session
1096 * keyring; otherwise, it must grant Search permission directly to the caller.
1098 * Returns a pointer to the keyring with the keyring's refcount having being
1099 * incremented on success. -ENOKEY is returned if a key could not be found.
1101 struct key *find_keyring_by_name(const char *name, bool uid_keyring)
1103 struct key *keyring;
1107 return ERR_PTR(-EINVAL);
1109 bucket = keyring_hash(name);
1111 read_lock(&keyring_name_lock);
1113 if (keyring_name_hash[bucket].next) {
1114 /* search this hash bucket for a keyring with a matching name
1115 * that's readable and that hasn't been revoked */
1116 list_for_each_entry(keyring,
1117 &keyring_name_hash[bucket],
1120 if (!kuid_has_mapping(current_user_ns(), keyring->user->uid))
1123 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1126 if (strcmp(keyring->description, name) != 0)
1130 if (!test_bit(KEY_FLAG_UID_KEYRING,
1134 if (key_permission(make_key_ref(keyring, 0),
1135 KEY_NEED_SEARCH) < 0)
1139 /* we've got a match but we might end up racing with
1140 * key_cleanup() if the keyring is currently 'dead'
1141 * (ie. it has a zero usage count) */
1142 if (!refcount_inc_not_zero(&keyring->usage))
1144 keyring->last_used_at = ktime_get_real_seconds();
1149 keyring = ERR_PTR(-ENOKEY);
1151 read_unlock(&keyring_name_lock);
1155 static int keyring_detect_cycle_iterator(const void *object,
1156 void *iterator_data)
1158 struct keyring_search_context *ctx = iterator_data;
1159 const struct key *key = keyring_ptr_to_key(object);
1161 kenter("{%d}", key->serial);
1163 /* We might get a keyring with matching index-key that is nonetheless a
1164 * different keyring. */
1165 if (key != ctx->match_data.raw_data)
1168 ctx->result = ERR_PTR(-EDEADLK);
1173 * See if a cycle will will be created by inserting acyclic tree B in acyclic
1174 * tree A at the topmost level (ie: as a direct child of A).
1176 * Since we are adding B to A at the top level, checking for cycles should just
1177 * be a matter of seeing if node A is somewhere in tree B.
1179 static int keyring_detect_cycle(struct key *A, struct key *B)
1181 struct keyring_search_context ctx = {
1182 .index_key = A->index_key,
1183 .match_data.raw_data = A,
1184 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
1185 .iterator = keyring_detect_cycle_iterator,
1186 .flags = (KEYRING_SEARCH_NO_STATE_CHECK |
1187 KEYRING_SEARCH_NO_UPDATE_TIME |
1188 KEYRING_SEARCH_NO_CHECK_PERM |
1189 KEYRING_SEARCH_DETECT_TOO_DEEP),
1193 search_nested_keyrings(B, &ctx);
1195 return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);
1199 * Preallocate memory so that a key can be linked into to a keyring.
1201 int __key_link_begin(struct key *keyring,
1202 const struct keyring_index_key *index_key,
1203 struct assoc_array_edit **_edit)
1204 __acquires(&keyring->sem)
1205 __acquires(&keyring_serialise_link_sem)
1207 struct assoc_array_edit *edit;
1211 keyring->serial, index_key->type->name, index_key->description);
1213 BUG_ON(index_key->desc_len == 0);
1215 if (keyring->type != &key_type_keyring)
1218 down_write(&keyring->sem);
1221 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1224 /* serialise link/link calls to prevent parallel calls causing a cycle
1225 * when linking two keyring in opposite orders */
1226 if (index_key->type == &key_type_keyring)
1227 down_write(&keyring_serialise_link_sem);
1229 /* Create an edit script that will insert/replace the key in the
1232 edit = assoc_array_insert(&keyring->keys,
1233 &keyring_assoc_array_ops,
1237 ret = PTR_ERR(edit);
1241 /* If we're not replacing a link in-place then we're going to need some
1244 if (!edit->dead_leaf) {
1245 ret = key_payload_reserve(keyring,
1246 keyring->datalen + KEYQUOTA_LINK_BYTES);
1256 assoc_array_cancel_edit(edit);
1258 if (index_key->type == &key_type_keyring)
1259 up_write(&keyring_serialise_link_sem);
1261 up_write(&keyring->sem);
1262 kleave(" = %d", ret);
1267 * Check already instantiated keys aren't going to be a problem.
1269 * The caller must have called __key_link_begin(). Don't need to call this for
1270 * keys that were created since __key_link_begin() was called.
1272 int __key_link_check_live_key(struct key *keyring, struct key *key)
1274 if (key->type == &key_type_keyring)
1275 /* check that we aren't going to create a cycle by linking one
1276 * keyring to another */
1277 return keyring_detect_cycle(keyring, key);
1282 * Link a key into to a keyring.
1284 * Must be called with __key_link_begin() having being called. Discards any
1285 * already extant link to matching key if there is one, so that each keyring
1286 * holds at most one link to any given key of a particular type+description
1289 void __key_link(struct key *key, struct assoc_array_edit **_edit)
1292 assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key));
1293 assoc_array_apply_edit(*_edit);
1298 * Finish linking a key into to a keyring.
1300 * Must be called with __key_link_begin() having being called.
1302 void __key_link_end(struct key *keyring,
1303 const struct keyring_index_key *index_key,
1304 struct assoc_array_edit *edit)
1305 __releases(&keyring->sem)
1306 __releases(&keyring_serialise_link_sem)
1308 BUG_ON(index_key->type == NULL);
1309 kenter("%d,%s,", keyring->serial, index_key->type->name);
1311 if (index_key->type == &key_type_keyring)
1312 up_write(&keyring_serialise_link_sem);
1315 if (!edit->dead_leaf) {
1316 key_payload_reserve(keyring,
1317 keyring->datalen - KEYQUOTA_LINK_BYTES);
1319 assoc_array_cancel_edit(edit);
1321 up_write(&keyring->sem);
1325 * Check addition of keys to restricted keyrings.
1327 static int __key_link_check_restriction(struct key *keyring, struct key *key)
1329 if (!keyring->restrict_link || !keyring->restrict_link->check)
1331 return keyring->restrict_link->check(keyring, key->type, &key->payload,
1332 keyring->restrict_link->key);
1336 * key_link - Link a key to a keyring
1337 * @keyring: The keyring to make the link in.
1338 * @key: The key to link to.
1340 * Make a link in a keyring to a key, such that the keyring holds a reference
1341 * on that key and the key can potentially be found by searching that keyring.
1343 * This function will write-lock the keyring's semaphore and will consume some
1344 * of the user's key data quota to hold the link.
1346 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1347 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1348 * full, -EDQUOT if there is insufficient key data quota remaining to add
1349 * another link or -ENOMEM if there's insufficient memory.
1351 * It is assumed that the caller has checked that it is permitted for a link to
1352 * be made (the keyring should have Write permission and the key Link
1355 int key_link(struct key *keyring, struct key *key)
1357 struct assoc_array_edit *edit;
1360 kenter("{%d,%d}", keyring->serial, refcount_read(&keyring->usage));
1365 ret = __key_link_begin(keyring, &key->index_key, &edit);
1367 kdebug("begun {%d,%d}", keyring->serial, refcount_read(&keyring->usage));
1368 ret = __key_link_check_restriction(keyring, key);
1370 ret = __key_link_check_live_key(keyring, key);
1372 __key_link(key, &edit);
1373 __key_link_end(keyring, &key->index_key, edit);
1376 kleave(" = %d {%d,%d}", ret, keyring->serial, refcount_read(&keyring->usage));
1379 EXPORT_SYMBOL(key_link);
1382 * key_unlink - Unlink the first link to a key from a keyring.
1383 * @keyring: The keyring to remove the link from.
1384 * @key: The key the link is to.
1386 * Remove a link from a keyring to a key.
1388 * This function will write-lock the keyring's semaphore.
1390 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1391 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1394 * It is assumed that the caller has checked that it is permitted for a link to
1395 * be removed (the keyring should have Write permission; no permissions are
1396 * required on the key).
1398 int key_unlink(struct key *keyring, struct key *key)
1400 struct assoc_array_edit *edit;
1406 if (keyring->type != &key_type_keyring)
1409 down_write(&keyring->sem);
1411 edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
1414 ret = PTR_ERR(edit);
1421 assoc_array_apply_edit(edit);
1422 key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
1426 up_write(&keyring->sem);
1429 EXPORT_SYMBOL(key_unlink);
1432 * keyring_clear - Clear a keyring
1433 * @keyring: The keyring to clear.
1435 * Clear the contents of the specified keyring.
1437 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1439 int keyring_clear(struct key *keyring)
1441 struct assoc_array_edit *edit;
1444 if (keyring->type != &key_type_keyring)
1447 down_write(&keyring->sem);
1449 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1451 ret = PTR_ERR(edit);
1454 assoc_array_apply_edit(edit);
1455 key_payload_reserve(keyring, 0);
1459 up_write(&keyring->sem);
1462 EXPORT_SYMBOL(keyring_clear);
1465 * Dispose of the links from a revoked keyring.
1467 * This is called with the key sem write-locked.
1469 static void keyring_revoke(struct key *keyring)
1471 struct assoc_array_edit *edit;
1473 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1474 if (!IS_ERR(edit)) {
1476 assoc_array_apply_edit(edit);
1477 key_payload_reserve(keyring, 0);
1481 static bool keyring_gc_select_iterator(void *object, void *iterator_data)
1483 struct key *key = keyring_ptr_to_key(object);
1484 time64_t *limit = iterator_data;
1486 if (key_is_dead(key, *limit))
1492 static int keyring_gc_check_iterator(const void *object, void *iterator_data)
1494 const struct key *key = keyring_ptr_to_key(object);
1495 time64_t *limit = iterator_data;
1498 return key_is_dead(key, *limit);
1502 * Garbage collect pointers from a keyring.
1504 * Not called with any locks held. The keyring's key struct will not be
1505 * deallocated under us as only our caller may deallocate it.
1507 void keyring_gc(struct key *keyring, time64_t limit)
1511 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1513 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
1514 (1 << KEY_FLAG_REVOKED)))
1517 /* scan the keyring looking for dead keys */
1519 result = assoc_array_iterate(&keyring->keys,
1520 keyring_gc_check_iterator, &limit);
1530 down_write(&keyring->sem);
1531 assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops,
1532 keyring_gc_select_iterator, &limit);
1533 up_write(&keyring->sem);
1538 * Garbage collect restriction pointers from a keyring.
1540 * Keyring restrictions are associated with a key type, and must be cleaned
1541 * up if the key type is unregistered. The restriction is altered to always
1542 * reject additional keys so a keyring cannot be opened up by unregistering
1545 * Not called with any keyring locks held. The keyring's key struct will not
1546 * be deallocated under us as only our caller may deallocate it.
1548 * The caller is required to hold key_types_sem and dead_type->sem. This is
1549 * fulfilled by key_gc_keytype() holding the locks on behalf of
1550 * key_garbage_collector(), which it invokes on a workqueue.
1552 void keyring_restriction_gc(struct key *keyring, struct key_type *dead_type)
1554 struct key_restriction *keyres;
1556 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1559 * keyring->restrict_link is only assigned at key allocation time
1560 * or with the key type locked, so the only values that could be
1561 * concurrently assigned to keyring->restrict_link are for key
1562 * types other than dead_type. Given this, it's ok to check
1563 * the key type before acquiring keyring->sem.
1565 if (!dead_type || !keyring->restrict_link ||
1566 keyring->restrict_link->keytype != dead_type) {
1567 kleave(" [no restriction gc]");
1571 /* Lock the keyring to ensure that a link is not in progress */
1572 down_write(&keyring->sem);
1574 keyres = keyring->restrict_link;
1576 keyres->check = restrict_link_reject;
1578 key_put(keyres->key);
1580 keyres->keytype = NULL;
1582 up_write(&keyring->sem);
1584 kleave(" [restriction gc]");