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));
250 offset += sizeof(chunk) - 1;
251 offset += (level - 3) * sizeof(chunk);
252 if (offset >= desc_len)
260 chunk |= ((u8*)index_key->description)[--offset];
261 } while (--desc_len > 0);
265 chunk |= (u8)((unsigned long)index_key->type >>
266 (ASSOC_ARRAY_KEY_CHUNK_SIZE - 8));
272 static unsigned long keyring_get_object_key_chunk(const void *object, int level)
274 const struct key *key = keyring_ptr_to_key(object);
275 return keyring_get_key_chunk(&key->index_key, level);
278 static bool keyring_compare_object(const void *object, const void *data)
280 const struct keyring_index_key *index_key = data;
281 const struct key *key = keyring_ptr_to_key(object);
283 return key->index_key.type == index_key->type &&
284 key->index_key.desc_len == index_key->desc_len &&
285 memcmp(key->index_key.description, index_key->description,
286 index_key->desc_len) == 0;
290 * Compare the index keys of a pair of objects and determine the bit position
291 * at which they differ - if they differ.
293 static int keyring_diff_objects(const void *object, const void *data)
295 const struct key *key_a = keyring_ptr_to_key(object);
296 const struct keyring_index_key *a = &key_a->index_key;
297 const struct keyring_index_key *b = data;
298 unsigned long seg_a, seg_b;
302 seg_a = hash_key_type_and_desc(a);
303 seg_b = hash_key_type_and_desc(b);
304 if ((seg_a ^ seg_b) != 0)
307 /* The number of bits contributed by the hash is controlled by a
308 * constant in the assoc_array headers. Everything else thereafter we
309 * can deal with as being machine word-size dependent.
311 level += ASSOC_ARRAY_KEY_CHUNK_SIZE / 8;
314 if ((seg_a ^ seg_b) != 0)
317 /* The next bit may not work on big endian */
319 seg_a = (unsigned long)a->type;
320 seg_b = (unsigned long)b->type;
321 if ((seg_a ^ seg_b) != 0)
324 level += sizeof(unsigned long);
325 if (a->desc_len == 0)
329 if (((unsigned long)a->description | (unsigned long)b->description) &
330 (sizeof(unsigned long) - 1)) {
332 seg_a = *(unsigned long *)(a->description + i);
333 seg_b = *(unsigned long *)(b->description + i);
334 if ((seg_a ^ seg_b) != 0)
336 i += sizeof(unsigned long);
337 } while (i < (a->desc_len & (sizeof(unsigned long) - 1)));
340 for (; i < a->desc_len; i++) {
341 seg_a = *(unsigned char *)(a->description + i);
342 seg_b = *(unsigned char *)(b->description + i);
343 if ((seg_a ^ seg_b) != 0)
353 i = level * 8 + __ffs(seg_a ^ seg_b);
358 * Free an object after stripping the keyring flag off of the pointer.
360 static void keyring_free_object(void *object)
362 key_put(keyring_ptr_to_key(object));
366 * Operations for keyring management by the index-tree routines.
368 static const struct assoc_array_ops keyring_assoc_array_ops = {
369 .get_key_chunk = keyring_get_key_chunk,
370 .get_object_key_chunk = keyring_get_object_key_chunk,
371 .compare_object = keyring_compare_object,
372 .diff_objects = keyring_diff_objects,
373 .free_object = keyring_free_object,
377 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
378 * and dispose of its data.
380 * The garbage collector detects the final key_put(), removes the keyring from
381 * the serial number tree and then does RCU synchronisation before coming here,
382 * so we shouldn't need to worry about code poking around here with the RCU
383 * readlock held by this time.
385 static void keyring_destroy(struct key *keyring)
387 if (keyring->description) {
388 write_lock(&keyring_name_lock);
390 if (keyring->name_link.next != NULL &&
391 !list_empty(&keyring->name_link))
392 list_del(&keyring->name_link);
394 write_unlock(&keyring_name_lock);
397 if (keyring->restrict_link) {
398 struct key_restriction *keyres = keyring->restrict_link;
400 key_put(keyres->key);
404 assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops);
408 * Describe a keyring for /proc.
410 static void keyring_describe(const struct key *keyring, struct seq_file *m)
412 if (keyring->description)
413 seq_puts(m, keyring->description);
415 seq_puts(m, "[anon]");
417 if (key_is_positive(keyring)) {
418 if (keyring->keys.nr_leaves_on_tree != 0)
419 seq_printf(m, ": %lu", keyring->keys.nr_leaves_on_tree);
421 seq_puts(m, ": empty");
425 struct keyring_read_iterator_context {
428 key_serial_t __user *buffer;
431 static int keyring_read_iterator(const void *object, void *data)
433 struct keyring_read_iterator_context *ctx = data;
434 const struct key *key = keyring_ptr_to_key(object);
437 kenter("{%s,%d},,{%zu/%zu}",
438 key->type->name, key->serial, ctx->count, ctx->buflen);
440 if (ctx->count >= ctx->buflen)
443 ret = put_user(key->serial, ctx->buffer);
447 ctx->count += sizeof(key->serial);
452 * Read a list of key IDs from the keyring's contents in binary form
454 * The keyring's semaphore is read-locked by the caller. This prevents someone
455 * from modifying it under us - which could cause us to read key IDs multiple
458 static long keyring_read(const struct key *keyring,
459 char __user *buffer, size_t buflen)
461 struct keyring_read_iterator_context ctx;
464 kenter("{%d},,%zu", key_serial(keyring), buflen);
466 if (buflen & (sizeof(key_serial_t) - 1))
469 /* Copy as many key IDs as fit into the buffer */
470 if (buffer && buflen) {
471 ctx.buffer = (key_serial_t __user *)buffer;
474 ret = assoc_array_iterate(&keyring->keys,
475 keyring_read_iterator, &ctx);
477 kleave(" = %ld [iterate]", ret);
482 /* Return the size of the buffer needed */
483 ret = keyring->keys.nr_leaves_on_tree * sizeof(key_serial_t);
485 kleave("= %ld [ok]", ret);
487 kleave("= %ld [buffer too small]", ret);
492 * Allocate a keyring and link into the destination keyring.
494 struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
495 const struct cred *cred, key_perm_t perm,
497 struct key_restriction *restrict_link,
503 keyring = key_alloc(&key_type_keyring, description,
504 uid, gid, cred, perm, flags, restrict_link);
505 if (!IS_ERR(keyring)) {
506 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
509 keyring = ERR_PTR(ret);
515 EXPORT_SYMBOL(keyring_alloc);
518 * restrict_link_reject - Give -EPERM to restrict link
519 * @keyring: The keyring being added to.
520 * @type: The type of key being added.
521 * @payload: The payload of the key intended to be added.
522 * @data: Additional data for evaluating restriction.
524 * Reject the addition of any links to a keyring. It can be overridden by
525 * passing KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when
526 * adding a key to a keyring.
528 * This is meant to be stored in a key_restriction structure which is passed
529 * in the restrict_link parameter to keyring_alloc().
531 int restrict_link_reject(struct key *keyring,
532 const struct key_type *type,
533 const union key_payload *payload,
534 struct key *restriction_key)
540 * By default, we keys found by getting an exact match on their descriptions.
542 bool key_default_cmp(const struct key *key,
543 const struct key_match_data *match_data)
545 return strcmp(key->description, match_data->raw_data) == 0;
549 * Iteration function to consider each key found.
551 static int keyring_search_iterator(const void *object, void *iterator_data)
553 struct keyring_search_context *ctx = iterator_data;
554 const struct key *key = keyring_ptr_to_key(object);
555 unsigned long kflags = READ_ONCE(key->flags);
556 short state = READ_ONCE(key->state);
558 kenter("{%d}", key->serial);
560 /* ignore keys not of this type */
561 if (key->type != ctx->index_key.type) {
562 kleave(" = 0 [!type]");
566 /* skip invalidated, revoked and expired keys */
567 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
568 time64_t expiry = READ_ONCE(key->expiry);
570 if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
571 (1 << KEY_FLAG_REVOKED))) {
572 ctx->result = ERR_PTR(-EKEYREVOKED);
573 kleave(" = %d [invrev]", ctx->skipped_ret);
577 if (expiry && ctx->now >= expiry) {
578 if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
579 ctx->result = ERR_PTR(-EKEYEXPIRED);
580 kleave(" = %d [expire]", ctx->skipped_ret);
585 /* keys that don't match */
586 if (!ctx->match_data.cmp(key, &ctx->match_data)) {
587 kleave(" = 0 [!match]");
591 /* key must have search permissions */
592 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
593 key_task_permission(make_key_ref(key, ctx->possessed),
594 ctx->cred, KEY_NEED_SEARCH) < 0) {
595 ctx->result = ERR_PTR(-EACCES);
596 kleave(" = %d [!perm]", ctx->skipped_ret);
600 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
601 /* we set a different error code if we pass a negative key */
603 ctx->result = ERR_PTR(state);
604 kleave(" = %d [neg]", ctx->skipped_ret);
610 ctx->result = make_key_ref(key, ctx->possessed);
611 kleave(" = 1 [found]");
615 return ctx->skipped_ret;
619 * Search inside a keyring for a key. We can search by walking to it
620 * directly based on its index-key or we can iterate over the entire
621 * tree looking for it, based on the match function.
623 static int search_keyring(struct key *keyring, struct keyring_search_context *ctx)
625 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_DIRECT) {
628 object = assoc_array_find(&keyring->keys,
629 &keyring_assoc_array_ops,
631 return object ? ctx->iterator(object, ctx) : 0;
633 return assoc_array_iterate(&keyring->keys, ctx->iterator, ctx);
637 * Search a tree of keyrings that point to other keyrings up to the maximum
640 static bool search_nested_keyrings(struct key *keyring,
641 struct keyring_search_context *ctx)
645 struct assoc_array_node *node;
647 } stack[KEYRING_SEARCH_MAX_DEPTH];
649 struct assoc_array_shortcut *shortcut;
650 struct assoc_array_node *node;
651 struct assoc_array_ptr *ptr;
655 kenter("{%d},{%s,%s}",
657 ctx->index_key.type->name,
658 ctx->index_key.description);
660 #define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK)
661 BUG_ON((ctx->flags & STATE_CHECKS) == 0 ||
662 (ctx->flags & STATE_CHECKS) == STATE_CHECKS);
664 /* Check to see if this top-level keyring is what we are looking for
665 * and whether it is valid or not.
667 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE ||
668 keyring_compare_object(keyring, &ctx->index_key)) {
669 ctx->skipped_ret = 2;
670 switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) {
680 ctx->skipped_ret = 0;
682 /* Start processing a new keyring */
684 kdebug("descend to %d", keyring->serial);
685 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
686 (1 << KEY_FLAG_REVOKED)))
687 goto not_this_keyring;
689 /* Search through the keys in this keyring before its searching its
692 if (search_keyring(keyring, ctx))
695 /* Then manually iterate through the keyrings nested in this one.
697 * Start from the root node of the index tree. Because of the way the
698 * hash function has been set up, keyrings cluster on the leftmost
699 * branch of the root node (root slot 0) or in the root node itself.
700 * Non-keyrings avoid the leftmost branch of the root entirely (root
703 ptr = READ_ONCE(keyring->keys.root);
705 goto not_this_keyring;
707 if (assoc_array_ptr_is_shortcut(ptr)) {
708 /* If the root is a shortcut, either the keyring only contains
709 * keyring pointers (everything clusters behind root slot 0) or
710 * doesn't contain any keyring pointers.
712 shortcut = assoc_array_ptr_to_shortcut(ptr);
713 if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
714 goto not_this_keyring;
716 ptr = READ_ONCE(shortcut->next_node);
717 node = assoc_array_ptr_to_node(ptr);
721 node = assoc_array_ptr_to_node(ptr);
722 ptr = node->slots[0];
723 if (!assoc_array_ptr_is_meta(ptr))
727 /* Descend to a more distal node in this keyring's content tree and go
731 if (assoc_array_ptr_is_shortcut(ptr)) {
732 shortcut = assoc_array_ptr_to_shortcut(ptr);
733 ptr = READ_ONCE(shortcut->next_node);
734 BUG_ON(!assoc_array_ptr_is_node(ptr));
736 node = assoc_array_ptr_to_node(ptr);
739 kdebug("begin_node");
742 /* Go through the slots in a node */
743 for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
744 ptr = READ_ONCE(node->slots[slot]);
746 if (assoc_array_ptr_is_meta(ptr) && node->back_pointer)
747 goto descend_to_node;
749 if (!keyring_ptr_is_keyring(ptr))
752 key = keyring_ptr_to_key(ptr);
754 if (sp >= KEYRING_SEARCH_MAX_DEPTH) {
755 if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) {
756 ctx->result = ERR_PTR(-ELOOP);
759 goto not_this_keyring;
762 /* Search a nested keyring */
763 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
764 key_task_permission(make_key_ref(key, ctx->possessed),
765 ctx->cred, KEY_NEED_SEARCH) < 0)
768 /* stack the current position */
769 stack[sp].keyring = keyring;
770 stack[sp].node = node;
771 stack[sp].slot = slot;
774 /* begin again with the new keyring */
776 goto descend_to_keyring;
779 /* We've dealt with all the slots in the current node, so now we need
780 * to ascend to the parent and continue processing there.
782 ptr = READ_ONCE(node->back_pointer);
783 slot = node->parent_slot;
785 if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
786 shortcut = assoc_array_ptr_to_shortcut(ptr);
787 ptr = READ_ONCE(shortcut->back_pointer);
788 slot = shortcut->parent_slot;
791 goto not_this_keyring;
792 node = assoc_array_ptr_to_node(ptr);
795 /* If we've ascended to the root (zero backpointer), we must have just
796 * finished processing the leftmost branch rather than the root slots -
797 * so there can't be any more keyrings for us to find.
799 if (node->back_pointer) {
800 kdebug("ascend %d", slot);
804 /* The keyring we're looking at was disqualified or didn't contain a
808 kdebug("not_this_keyring %d", sp);
814 /* Resume the processing of a keyring higher up in the tree */
816 keyring = stack[sp].keyring;
817 node = stack[sp].node;
818 slot = stack[sp].slot + 1;
819 kdebug("ascend to %d [%d]", keyring->serial, slot);
822 /* We found a viable match */
824 key = key_ref_to_ptr(ctx->result);
826 if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) {
827 key->last_used_at = ctx->now;
828 keyring->last_used_at = ctx->now;
830 stack[--sp].keyring->last_used_at = ctx->now;
837 * keyring_search_aux - Search a keyring tree for a key matching some criteria
838 * @keyring_ref: A pointer to the keyring with possession indicator.
839 * @ctx: The keyring search context.
841 * Search the supplied keyring tree for a key that matches the criteria given.
842 * The root keyring and any linked keyrings must grant Search permission to the
843 * caller to be searchable and keys can only be found if they too grant Search
844 * to the caller. The possession flag on the root keyring pointer controls use
845 * of the possessor bits in permissions checking of the entire tree. In
846 * addition, the LSM gets to forbid keyring searches and key matches.
848 * The search is performed as a breadth-then-depth search up to the prescribed
849 * limit (KEYRING_SEARCH_MAX_DEPTH).
851 * Keys are matched to the type provided and are then filtered by the match
852 * function, which is given the description to use in any way it sees fit. The
853 * match function may use any attributes of a key that it wishes to to
854 * determine the match. Normally the match function from the key type would be
857 * RCU can be used to prevent the keyring key lists from disappearing without
858 * the need to take lots of locks.
860 * Returns a pointer to the found key and increments the key usage count if
861 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
862 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
863 * specified keyring wasn't a keyring.
865 * In the case of a successful return, the possession attribute from
866 * @keyring_ref is propagated to the returned key reference.
868 key_ref_t keyring_search_aux(key_ref_t keyring_ref,
869 struct keyring_search_context *ctx)
874 ctx->iterator = keyring_search_iterator;
875 ctx->possessed = is_key_possessed(keyring_ref);
876 ctx->result = ERR_PTR(-EAGAIN);
878 keyring = key_ref_to_ptr(keyring_ref);
881 if (keyring->type != &key_type_keyring)
882 return ERR_PTR(-ENOTDIR);
884 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) {
885 err = key_task_permission(keyring_ref, ctx->cred, KEY_NEED_SEARCH);
891 ctx->now = ktime_get_real_seconds();
892 if (search_nested_keyrings(keyring, ctx))
893 __key_get(key_ref_to_ptr(ctx->result));
899 * keyring_search - Search the supplied keyring tree for a matching key
900 * @keyring: The root of the keyring tree to be searched.
901 * @type: The type of keyring we want to find.
902 * @description: The name of the keyring we want to find.
904 * As keyring_search_aux() above, but using the current task's credentials and
905 * type's default matching function and preferred search method.
907 key_ref_t keyring_search(key_ref_t keyring,
908 struct key_type *type,
909 const char *description)
911 struct keyring_search_context ctx = {
912 .index_key.type = type,
913 .index_key.description = description,
914 .index_key.desc_len = strlen(description),
915 .cred = current_cred(),
916 .match_data.cmp = key_default_cmp,
917 .match_data.raw_data = description,
918 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
919 .flags = KEYRING_SEARCH_DO_STATE_CHECK,
924 if (type->match_preparse) {
925 ret = type->match_preparse(&ctx.match_data);
930 key = keyring_search_aux(keyring, &ctx);
932 if (type->match_free)
933 type->match_free(&ctx.match_data);
936 EXPORT_SYMBOL(keyring_search);
938 static struct key_restriction *keyring_restriction_alloc(
939 key_restrict_link_func_t check)
941 struct key_restriction *keyres =
942 kzalloc(sizeof(struct key_restriction), GFP_KERNEL);
945 return ERR_PTR(-ENOMEM);
947 keyres->check = check;
953 * Semaphore to serialise restriction setup to prevent reference count
954 * cycles through restriction key pointers.
956 static DECLARE_RWSEM(keyring_serialise_restrict_sem);
959 * Check for restriction cycles that would prevent keyring garbage collection.
960 * keyring_serialise_restrict_sem must be held.
962 static bool keyring_detect_restriction_cycle(const struct key *dest_keyring,
963 struct key_restriction *keyres)
965 while (keyres && keyres->key &&
966 keyres->key->type == &key_type_keyring) {
967 if (keyres->key == dest_keyring)
970 keyres = keyres->key->restrict_link;
977 * keyring_restrict - Look up and apply a restriction to a keyring
979 * @keyring: The keyring to be restricted
980 * @restriction: The restriction options to apply to the keyring
982 int keyring_restrict(key_ref_t keyring_ref, const char *type,
983 const char *restriction)
986 struct key_type *restrict_type = NULL;
987 struct key_restriction *restrict_link;
990 keyring = key_ref_to_ptr(keyring_ref);
993 if (keyring->type != &key_type_keyring)
997 restrict_link = keyring_restriction_alloc(restrict_link_reject);
999 restrict_type = key_type_lookup(type);
1001 if (IS_ERR(restrict_type))
1002 return PTR_ERR(restrict_type);
1004 if (!restrict_type->lookup_restriction) {
1009 restrict_link = restrict_type->lookup_restriction(restriction);
1012 if (IS_ERR(restrict_link)) {
1013 ret = PTR_ERR(restrict_link);
1017 down_write(&keyring->sem);
1018 down_write(&keyring_serialise_restrict_sem);
1020 if (keyring->restrict_link)
1022 else if (keyring_detect_restriction_cycle(keyring, restrict_link))
1025 keyring->restrict_link = restrict_link;
1027 up_write(&keyring_serialise_restrict_sem);
1028 up_write(&keyring->sem);
1031 key_put(restrict_link->key);
1032 kfree(restrict_link);
1037 key_type_put(restrict_type);
1041 EXPORT_SYMBOL(keyring_restrict);
1044 * Search the given keyring for a key that might be updated.
1046 * The caller must guarantee that the keyring is a keyring and that the
1047 * permission is granted to modify the keyring as no check is made here. The
1048 * caller must also hold a lock on the keyring semaphore.
1050 * Returns a pointer to the found key with usage count incremented if
1051 * successful and returns NULL if not found. Revoked and invalidated keys are
1054 * If successful, the possession indicator is propagated from the keyring ref
1055 * to the returned key reference.
1057 key_ref_t find_key_to_update(key_ref_t keyring_ref,
1058 const struct keyring_index_key *index_key)
1060 struct key *keyring, *key;
1063 keyring = key_ref_to_ptr(keyring_ref);
1065 kenter("{%d},{%s,%s}",
1066 keyring->serial, index_key->type->name, index_key->description);
1068 object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops,
1078 key = keyring_ptr_to_key(object);
1079 if (key->flags & ((1 << KEY_FLAG_INVALIDATED) |
1080 (1 << KEY_FLAG_REVOKED))) {
1081 kleave(" = NULL [x]");
1085 kleave(" = {%d}", key->serial);
1086 return make_key_ref(key, is_key_possessed(keyring_ref));
1090 * Find a keyring with the specified name.
1092 * Only keyrings that have nonzero refcount, are not revoked, and are owned by a
1093 * user in the current user namespace are considered. If @uid_keyring is %true,
1094 * the keyring additionally must have been allocated as a user or user session
1095 * keyring; otherwise, it must grant Search permission directly to the caller.
1097 * Returns a pointer to the keyring with the keyring's refcount having being
1098 * incremented on success. -ENOKEY is returned if a key could not be found.
1100 struct key *find_keyring_by_name(const char *name, bool uid_keyring)
1102 struct key *keyring;
1106 return ERR_PTR(-EINVAL);
1108 bucket = keyring_hash(name);
1110 read_lock(&keyring_name_lock);
1112 if (keyring_name_hash[bucket].next) {
1113 /* search this hash bucket for a keyring with a matching name
1114 * that's readable and that hasn't been revoked */
1115 list_for_each_entry(keyring,
1116 &keyring_name_hash[bucket],
1119 if (!kuid_has_mapping(current_user_ns(), keyring->user->uid))
1122 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1125 if (strcmp(keyring->description, name) != 0)
1129 if (!test_bit(KEY_FLAG_UID_KEYRING,
1133 if (key_permission(make_key_ref(keyring, 0),
1134 KEY_NEED_SEARCH) < 0)
1138 /* we've got a match but we might end up racing with
1139 * key_cleanup() if the keyring is currently 'dead'
1140 * (ie. it has a zero usage count) */
1141 if (!refcount_inc_not_zero(&keyring->usage))
1143 keyring->last_used_at = ktime_get_real_seconds();
1148 keyring = ERR_PTR(-ENOKEY);
1150 read_unlock(&keyring_name_lock);
1154 static int keyring_detect_cycle_iterator(const void *object,
1155 void *iterator_data)
1157 struct keyring_search_context *ctx = iterator_data;
1158 const struct key *key = keyring_ptr_to_key(object);
1160 kenter("{%d}", key->serial);
1162 /* We might get a keyring with matching index-key that is nonetheless a
1163 * different keyring. */
1164 if (key != ctx->match_data.raw_data)
1167 ctx->result = ERR_PTR(-EDEADLK);
1172 * See if a cycle will will be created by inserting acyclic tree B in acyclic
1173 * tree A at the topmost level (ie: as a direct child of A).
1175 * Since we are adding B to A at the top level, checking for cycles should just
1176 * be a matter of seeing if node A is somewhere in tree B.
1178 static int keyring_detect_cycle(struct key *A, struct key *B)
1180 struct keyring_search_context ctx = {
1181 .index_key = A->index_key,
1182 .match_data.raw_data = A,
1183 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
1184 .iterator = keyring_detect_cycle_iterator,
1185 .flags = (KEYRING_SEARCH_NO_STATE_CHECK |
1186 KEYRING_SEARCH_NO_UPDATE_TIME |
1187 KEYRING_SEARCH_NO_CHECK_PERM |
1188 KEYRING_SEARCH_DETECT_TOO_DEEP),
1192 search_nested_keyrings(B, &ctx);
1194 return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);
1198 * Preallocate memory so that a key can be linked into to a keyring.
1200 int __key_link_begin(struct key *keyring,
1201 const struct keyring_index_key *index_key,
1202 struct assoc_array_edit **_edit)
1203 __acquires(&keyring->sem)
1204 __acquires(&keyring_serialise_link_sem)
1206 struct assoc_array_edit *edit;
1210 keyring->serial, index_key->type->name, index_key->description);
1212 BUG_ON(index_key->desc_len == 0);
1214 if (keyring->type != &key_type_keyring)
1217 down_write(&keyring->sem);
1220 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1223 /* serialise link/link calls to prevent parallel calls causing a cycle
1224 * when linking two keyring in opposite orders */
1225 if (index_key->type == &key_type_keyring)
1226 down_write(&keyring_serialise_link_sem);
1228 /* Create an edit script that will insert/replace the key in the
1231 edit = assoc_array_insert(&keyring->keys,
1232 &keyring_assoc_array_ops,
1236 ret = PTR_ERR(edit);
1240 /* If we're not replacing a link in-place then we're going to need some
1243 if (!edit->dead_leaf) {
1244 ret = key_payload_reserve(keyring,
1245 keyring->datalen + KEYQUOTA_LINK_BYTES);
1255 assoc_array_cancel_edit(edit);
1257 if (index_key->type == &key_type_keyring)
1258 up_write(&keyring_serialise_link_sem);
1260 up_write(&keyring->sem);
1261 kleave(" = %d", ret);
1266 * Check already instantiated keys aren't going to be a problem.
1268 * The caller must have called __key_link_begin(). Don't need to call this for
1269 * keys that were created since __key_link_begin() was called.
1271 int __key_link_check_live_key(struct key *keyring, struct key *key)
1273 if (key->type == &key_type_keyring)
1274 /* check that we aren't going to create a cycle by linking one
1275 * keyring to another */
1276 return keyring_detect_cycle(keyring, key);
1281 * Link a key into to a keyring.
1283 * Must be called with __key_link_begin() having being called. Discards any
1284 * already extant link to matching key if there is one, so that each keyring
1285 * holds at most one link to any given key of a particular type+description
1288 void __key_link(struct key *key, struct assoc_array_edit **_edit)
1291 assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key));
1292 assoc_array_apply_edit(*_edit);
1297 * Finish linking a key into to a keyring.
1299 * Must be called with __key_link_begin() having being called.
1301 void __key_link_end(struct key *keyring,
1302 const struct keyring_index_key *index_key,
1303 struct assoc_array_edit *edit)
1304 __releases(&keyring->sem)
1305 __releases(&keyring_serialise_link_sem)
1307 BUG_ON(index_key->type == NULL);
1308 kenter("%d,%s,", keyring->serial, index_key->type->name);
1310 if (index_key->type == &key_type_keyring)
1311 up_write(&keyring_serialise_link_sem);
1314 if (!edit->dead_leaf) {
1315 key_payload_reserve(keyring,
1316 keyring->datalen - KEYQUOTA_LINK_BYTES);
1318 assoc_array_cancel_edit(edit);
1320 up_write(&keyring->sem);
1324 * Check addition of keys to restricted keyrings.
1326 static int __key_link_check_restriction(struct key *keyring, struct key *key)
1328 if (!keyring->restrict_link || !keyring->restrict_link->check)
1330 return keyring->restrict_link->check(keyring, key->type, &key->payload,
1331 keyring->restrict_link->key);
1335 * key_link - Link a key to a keyring
1336 * @keyring: The keyring to make the link in.
1337 * @key: The key to link to.
1339 * Make a link in a keyring to a key, such that the keyring holds a reference
1340 * on that key and the key can potentially be found by searching that keyring.
1342 * This function will write-lock the keyring's semaphore and will consume some
1343 * of the user's key data quota to hold the link.
1345 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1346 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1347 * full, -EDQUOT if there is insufficient key data quota remaining to add
1348 * another link or -ENOMEM if there's insufficient memory.
1350 * It is assumed that the caller has checked that it is permitted for a link to
1351 * be made (the keyring should have Write permission and the key Link
1354 int key_link(struct key *keyring, struct key *key)
1356 struct assoc_array_edit *edit;
1359 kenter("{%d,%d}", keyring->serial, refcount_read(&keyring->usage));
1364 ret = __key_link_begin(keyring, &key->index_key, &edit);
1366 kdebug("begun {%d,%d}", keyring->serial, refcount_read(&keyring->usage));
1367 ret = __key_link_check_restriction(keyring, key);
1369 ret = __key_link_check_live_key(keyring, key);
1371 __key_link(key, &edit);
1372 __key_link_end(keyring, &key->index_key, edit);
1375 kleave(" = %d {%d,%d}", ret, keyring->serial, refcount_read(&keyring->usage));
1378 EXPORT_SYMBOL(key_link);
1381 * key_unlink - Unlink the first link to a key from a keyring.
1382 * @keyring: The keyring to remove the link from.
1383 * @key: The key the link is to.
1385 * Remove a link from a keyring to a key.
1387 * This function will write-lock the keyring's semaphore.
1389 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1390 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1393 * It is assumed that the caller has checked that it is permitted for a link to
1394 * be removed (the keyring should have Write permission; no permissions are
1395 * required on the key).
1397 int key_unlink(struct key *keyring, struct key *key)
1399 struct assoc_array_edit *edit;
1405 if (keyring->type != &key_type_keyring)
1408 down_write(&keyring->sem);
1410 edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
1413 ret = PTR_ERR(edit);
1420 assoc_array_apply_edit(edit);
1421 key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
1425 up_write(&keyring->sem);
1428 EXPORT_SYMBOL(key_unlink);
1431 * keyring_clear - Clear a keyring
1432 * @keyring: The keyring to clear.
1434 * Clear the contents of the specified keyring.
1436 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1438 int keyring_clear(struct key *keyring)
1440 struct assoc_array_edit *edit;
1443 if (keyring->type != &key_type_keyring)
1446 down_write(&keyring->sem);
1448 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1450 ret = PTR_ERR(edit);
1453 assoc_array_apply_edit(edit);
1454 key_payload_reserve(keyring, 0);
1458 up_write(&keyring->sem);
1461 EXPORT_SYMBOL(keyring_clear);
1464 * Dispose of the links from a revoked keyring.
1466 * This is called with the key sem write-locked.
1468 static void keyring_revoke(struct key *keyring)
1470 struct assoc_array_edit *edit;
1472 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1473 if (!IS_ERR(edit)) {
1475 assoc_array_apply_edit(edit);
1476 key_payload_reserve(keyring, 0);
1480 static bool keyring_gc_select_iterator(void *object, void *iterator_data)
1482 struct key *key = keyring_ptr_to_key(object);
1483 time64_t *limit = iterator_data;
1485 if (key_is_dead(key, *limit))
1491 static int keyring_gc_check_iterator(const void *object, void *iterator_data)
1493 const struct key *key = keyring_ptr_to_key(object);
1494 time64_t *limit = iterator_data;
1497 return key_is_dead(key, *limit);
1501 * Garbage collect pointers from a keyring.
1503 * Not called with any locks held. The keyring's key struct will not be
1504 * deallocated under us as only our caller may deallocate it.
1506 void keyring_gc(struct key *keyring, time64_t limit)
1510 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1512 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
1513 (1 << KEY_FLAG_REVOKED)))
1516 /* scan the keyring looking for dead keys */
1518 result = assoc_array_iterate(&keyring->keys,
1519 keyring_gc_check_iterator, &limit);
1529 down_write(&keyring->sem);
1530 assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops,
1531 keyring_gc_select_iterator, &limit);
1532 up_write(&keyring->sem);
1537 * Garbage collect restriction pointers from a keyring.
1539 * Keyring restrictions are associated with a key type, and must be cleaned
1540 * up if the key type is unregistered. The restriction is altered to always
1541 * reject additional keys so a keyring cannot be opened up by unregistering
1544 * Not called with any keyring locks held. The keyring's key struct will not
1545 * be deallocated under us as only our caller may deallocate it.
1547 * The caller is required to hold key_types_sem and dead_type->sem. This is
1548 * fulfilled by key_gc_keytype() holding the locks on behalf of
1549 * key_garbage_collector(), which it invokes on a workqueue.
1551 void keyring_restriction_gc(struct key *keyring, struct key_type *dead_type)
1553 struct key_restriction *keyres;
1555 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1558 * keyring->restrict_link is only assigned at key allocation time
1559 * or with the key type locked, so the only values that could be
1560 * concurrently assigned to keyring->restrict_link are for key
1561 * types other than dead_type. Given this, it's ok to check
1562 * the key type before acquiring keyring->sem.
1564 if (!dead_type || !keyring->restrict_link ||
1565 keyring->restrict_link->keytype != dead_type) {
1566 kleave(" [no restriction gc]");
1570 /* Lock the keyring to ensure that a link is not in progress */
1571 down_write(&keyring->sem);
1573 keyres = keyring->restrict_link;
1575 keyres->check = restrict_link_reject;
1577 key_put(keyres->key);
1579 keyres->keytype = NULL;
1581 up_write(&keyring->sem);
1583 kleave(" [restriction gc]");