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/module.h>
13 #include <linux/init.h>
14 #include <linux/sched.h>
15 #include <linux/slab.h>
16 #include <linux/security.h>
17 #include <linux/seq_file.h>
18 #include <linux/err.h>
19 #include <keys/keyring-type.h>
20 #include <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 assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops);
401 * Describe a keyring for /proc.
403 static void keyring_describe(const struct key *keyring, struct seq_file *m)
405 if (keyring->description)
406 seq_puts(m, keyring->description);
408 seq_puts(m, "[anon]");
410 if (key_is_instantiated(keyring)) {
411 if (keyring->keys.nr_leaves_on_tree != 0)
412 seq_printf(m, ": %lu", keyring->keys.nr_leaves_on_tree);
414 seq_puts(m, ": empty");
418 struct keyring_read_iterator_context {
421 key_serial_t __user *buffer;
424 static int keyring_read_iterator(const void *object, void *data)
426 struct keyring_read_iterator_context *ctx = data;
427 const struct key *key = keyring_ptr_to_key(object);
430 kenter("{%s,%d},,{%zu/%zu}",
431 key->type->name, key->serial, ctx->count, ctx->qty);
433 if (ctx->count >= ctx->qty)
436 ret = put_user(key->serial, ctx->buffer);
440 ctx->count += sizeof(key->serial);
445 * Read a list of key IDs from the keyring's contents in binary form
447 * The keyring's semaphore is read-locked by the caller. This prevents someone
448 * from modifying it under us - which could cause us to read key IDs multiple
451 static long keyring_read(const struct key *keyring,
452 char __user *buffer, size_t buflen)
454 struct keyring_read_iterator_context ctx;
455 unsigned long nr_keys;
458 kenter("{%d},,%zu", key_serial(keyring), buflen);
460 if (buflen & (sizeof(key_serial_t) - 1))
463 nr_keys = keyring->keys.nr_leaves_on_tree;
467 /* Calculate how much data we could return */
468 ctx.qty = nr_keys * sizeof(key_serial_t);
470 if (!buffer || !buflen)
473 if (buflen > ctx.qty)
476 /* Copy the IDs of the subscribed keys into the buffer */
477 ctx.buffer = (key_serial_t __user *)buffer;
479 ret = assoc_array_iterate(&keyring->keys, keyring_read_iterator, &ctx);
481 kleave(" = %d [iterate]", ret);
485 kleave(" = %zu [ok]", ctx.count);
490 * Allocate a keyring and link into the destination keyring.
492 struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
493 const struct cred *cred, key_perm_t perm,
494 unsigned long flags, struct key *dest)
499 keyring = key_alloc(&key_type_keyring, description,
500 uid, gid, cred, perm, flags);
501 if (!IS_ERR(keyring)) {
502 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
505 keyring = ERR_PTR(ret);
511 EXPORT_SYMBOL(keyring_alloc);
514 * By default, we keys found by getting an exact match on their descriptions.
516 bool key_default_cmp(const struct key *key,
517 const struct key_match_data *match_data)
519 return strcmp(key->description, match_data->raw_data) == 0;
523 * Iteration function to consider each key found.
525 static int keyring_search_iterator(const void *object, void *iterator_data)
527 struct keyring_search_context *ctx = iterator_data;
528 const struct key *key = keyring_ptr_to_key(object);
529 unsigned long kflags = key->flags;
531 kenter("{%d}", key->serial);
533 /* ignore keys not of this type */
534 if (key->type != ctx->index_key.type) {
535 kleave(" = 0 [!type]");
539 /* skip invalidated, revoked and expired keys */
540 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
541 if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
542 (1 << KEY_FLAG_REVOKED))) {
543 ctx->result = ERR_PTR(-EKEYREVOKED);
544 kleave(" = %d [invrev]", ctx->skipped_ret);
548 if (key->expiry && ctx->now.tv_sec >= key->expiry) {
549 if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
550 ctx->result = ERR_PTR(-EKEYEXPIRED);
551 kleave(" = %d [expire]", ctx->skipped_ret);
556 /* keys that don't match */
557 if (!ctx->match_data.cmp(key, &ctx->match_data)) {
558 kleave(" = 0 [!match]");
562 /* key must have search permissions */
563 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
564 key_task_permission(make_key_ref(key, ctx->possessed),
565 ctx->cred, KEY_NEED_SEARCH) < 0) {
566 ctx->result = ERR_PTR(-EACCES);
567 kleave(" = %d [!perm]", ctx->skipped_ret);
571 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
572 /* we set a different error code if we pass a negative key */
573 if (kflags & (1 << KEY_FLAG_NEGATIVE)) {
575 ctx->result = ERR_PTR(key->reject_error);
576 kleave(" = %d [neg]", ctx->skipped_ret);
582 ctx->result = make_key_ref(key, ctx->possessed);
583 kleave(" = 1 [found]");
587 return ctx->skipped_ret;
591 * Search inside a keyring for a key. We can search by walking to it
592 * directly based on its index-key or we can iterate over the entire
593 * tree looking for it, based on the match function.
595 static int search_keyring(struct key *keyring, struct keyring_search_context *ctx)
597 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_DIRECT) {
600 object = assoc_array_find(&keyring->keys,
601 &keyring_assoc_array_ops,
603 return object ? ctx->iterator(object, ctx) : 0;
605 return assoc_array_iterate(&keyring->keys, ctx->iterator, ctx);
609 * Search a tree of keyrings that point to other keyrings up to the maximum
612 static bool search_nested_keyrings(struct key *keyring,
613 struct keyring_search_context *ctx)
617 struct assoc_array_node *node;
619 } stack[KEYRING_SEARCH_MAX_DEPTH];
621 struct assoc_array_shortcut *shortcut;
622 struct assoc_array_node *node;
623 struct assoc_array_ptr *ptr;
627 kenter("{%d},{%s,%s}",
629 ctx->index_key.type->name,
630 ctx->index_key.description);
632 #define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK)
633 BUG_ON((ctx->flags & STATE_CHECKS) == 0 ||
634 (ctx->flags & STATE_CHECKS) == STATE_CHECKS);
636 if (ctx->index_key.description)
637 ctx->index_key.desc_len = strlen(ctx->index_key.description);
639 /* Check to see if this top-level keyring is what we are looking for
640 * and whether it is valid or not.
642 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE ||
643 keyring_compare_object(keyring, &ctx->index_key)) {
644 ctx->skipped_ret = 2;
645 switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) {
655 ctx->skipped_ret = 0;
657 /* Start processing a new keyring */
659 kdebug("descend to %d", keyring->serial);
660 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
661 (1 << KEY_FLAG_REVOKED)))
662 goto not_this_keyring;
664 /* Search through the keys in this keyring before its searching its
667 if (search_keyring(keyring, ctx))
670 /* Then manually iterate through the keyrings nested in this one.
672 * Start from the root node of the index tree. Because of the way the
673 * hash function has been set up, keyrings cluster on the leftmost
674 * branch of the root node (root slot 0) or in the root node itself.
675 * Non-keyrings avoid the leftmost branch of the root entirely (root
678 ptr = ACCESS_ONCE(keyring->keys.root);
680 goto not_this_keyring;
682 if (assoc_array_ptr_is_shortcut(ptr)) {
683 /* If the root is a shortcut, either the keyring only contains
684 * keyring pointers (everything clusters behind root slot 0) or
685 * doesn't contain any keyring pointers.
687 shortcut = assoc_array_ptr_to_shortcut(ptr);
688 smp_read_barrier_depends();
689 if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
690 goto not_this_keyring;
692 ptr = ACCESS_ONCE(shortcut->next_node);
693 node = assoc_array_ptr_to_node(ptr);
697 node = assoc_array_ptr_to_node(ptr);
698 smp_read_barrier_depends();
700 ptr = node->slots[0];
701 if (!assoc_array_ptr_is_meta(ptr))
705 /* Descend to a more distal node in this keyring's content tree and go
709 if (assoc_array_ptr_is_shortcut(ptr)) {
710 shortcut = assoc_array_ptr_to_shortcut(ptr);
711 smp_read_barrier_depends();
712 ptr = ACCESS_ONCE(shortcut->next_node);
713 BUG_ON(!assoc_array_ptr_is_node(ptr));
715 node = assoc_array_ptr_to_node(ptr);
718 kdebug("begin_node");
719 smp_read_barrier_depends();
722 /* Go through the slots in a node */
723 for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
724 ptr = ACCESS_ONCE(node->slots[slot]);
726 if (assoc_array_ptr_is_meta(ptr) && node->back_pointer)
727 goto descend_to_node;
729 if (!keyring_ptr_is_keyring(ptr))
732 key = keyring_ptr_to_key(ptr);
734 if (sp >= KEYRING_SEARCH_MAX_DEPTH) {
735 if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) {
736 ctx->result = ERR_PTR(-ELOOP);
739 goto not_this_keyring;
742 /* Search a nested keyring */
743 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
744 key_task_permission(make_key_ref(key, ctx->possessed),
745 ctx->cred, KEY_NEED_SEARCH) < 0)
748 /* stack the current position */
749 stack[sp].keyring = keyring;
750 stack[sp].node = node;
751 stack[sp].slot = slot;
754 /* begin again with the new keyring */
756 goto descend_to_keyring;
759 /* We've dealt with all the slots in the current node, so now we need
760 * to ascend to the parent and continue processing there.
762 ptr = ACCESS_ONCE(node->back_pointer);
763 slot = node->parent_slot;
765 if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
766 shortcut = assoc_array_ptr_to_shortcut(ptr);
767 smp_read_barrier_depends();
768 ptr = ACCESS_ONCE(shortcut->back_pointer);
769 slot = shortcut->parent_slot;
772 goto not_this_keyring;
773 node = assoc_array_ptr_to_node(ptr);
774 smp_read_barrier_depends();
777 /* If we've ascended to the root (zero backpointer), we must have just
778 * finished processing the leftmost branch rather than the root slots -
779 * so there can't be any more keyrings for us to find.
781 if (node->back_pointer) {
782 kdebug("ascend %d", slot);
786 /* The keyring we're looking at was disqualified or didn't contain a
790 kdebug("not_this_keyring %d", sp);
796 /* Resume the processing of a keyring higher up in the tree */
798 keyring = stack[sp].keyring;
799 node = stack[sp].node;
800 slot = stack[sp].slot + 1;
801 kdebug("ascend to %d [%d]", keyring->serial, slot);
804 /* We found a viable match */
806 key = key_ref_to_ptr(ctx->result);
808 if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) {
809 key->last_used_at = ctx->now.tv_sec;
810 keyring->last_used_at = ctx->now.tv_sec;
812 stack[--sp].keyring->last_used_at = ctx->now.tv_sec;
819 * keyring_search_aux - Search a keyring tree for a key matching some criteria
820 * @keyring_ref: A pointer to the keyring with possession indicator.
821 * @ctx: The keyring search context.
823 * Search the supplied keyring tree for a key that matches the criteria given.
824 * The root keyring and any linked keyrings must grant Search permission to the
825 * caller to be searchable and keys can only be found if they too grant Search
826 * to the caller. The possession flag on the root keyring pointer controls use
827 * of the possessor bits in permissions checking of the entire tree. In
828 * addition, the LSM gets to forbid keyring searches and key matches.
830 * The search is performed as a breadth-then-depth search up to the prescribed
831 * limit (KEYRING_SEARCH_MAX_DEPTH).
833 * Keys are matched to the type provided and are then filtered by the match
834 * function, which is given the description to use in any way it sees fit. The
835 * match function may use any attributes of a key that it wishes to to
836 * determine the match. Normally the match function from the key type would be
839 * RCU can be used to prevent the keyring key lists from disappearing without
840 * the need to take lots of locks.
842 * Returns a pointer to the found key and increments the key usage count if
843 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
844 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
845 * specified keyring wasn't a keyring.
847 * In the case of a successful return, the possession attribute from
848 * @keyring_ref is propagated to the returned key reference.
850 key_ref_t keyring_search_aux(key_ref_t keyring_ref,
851 struct keyring_search_context *ctx)
856 ctx->iterator = keyring_search_iterator;
857 ctx->possessed = is_key_possessed(keyring_ref);
858 ctx->result = ERR_PTR(-EAGAIN);
860 keyring = key_ref_to_ptr(keyring_ref);
863 if (keyring->type != &key_type_keyring)
864 return ERR_PTR(-ENOTDIR);
866 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) {
867 err = key_task_permission(keyring_ref, ctx->cred, KEY_NEED_SEARCH);
873 ctx->now = current_kernel_time();
874 if (search_nested_keyrings(keyring, ctx))
875 __key_get(key_ref_to_ptr(ctx->result));
881 * keyring_search - Search the supplied keyring tree for a matching key
882 * @keyring: The root of the keyring tree to be searched.
883 * @type: The type of keyring we want to find.
884 * @description: The name of the keyring we want to find.
886 * As keyring_search_aux() above, but using the current task's credentials and
887 * type's default matching function and preferred search method.
889 key_ref_t keyring_search(key_ref_t keyring,
890 struct key_type *type,
891 const char *description)
893 struct keyring_search_context ctx = {
894 .index_key.type = type,
895 .index_key.description = description,
896 .cred = current_cred(),
897 .match_data.cmp = key_default_cmp,
898 .match_data.raw_data = description,
899 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
900 .flags = KEYRING_SEARCH_DO_STATE_CHECK,
905 if (type->match_preparse) {
906 ret = type->match_preparse(&ctx.match_data);
911 key = keyring_search_aux(keyring, &ctx);
913 if (type->match_free)
914 type->match_free(&ctx.match_data);
917 EXPORT_SYMBOL(keyring_search);
920 * Search the given keyring for a key that might be updated.
922 * The caller must guarantee that the keyring is a keyring and that the
923 * permission is granted to modify the keyring as no check is made here. The
924 * caller must also hold a lock on the keyring semaphore.
926 * Returns a pointer to the found key with usage count incremented if
927 * successful and returns NULL if not found. Revoked and invalidated keys are
930 * If successful, the possession indicator is propagated from the keyring ref
931 * to the returned key reference.
933 key_ref_t find_key_to_update(key_ref_t keyring_ref,
934 const struct keyring_index_key *index_key)
936 struct key *keyring, *key;
939 keyring = key_ref_to_ptr(keyring_ref);
941 kenter("{%d},{%s,%s}",
942 keyring->serial, index_key->type->name, index_key->description);
944 object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops,
954 key = keyring_ptr_to_key(object);
955 if (key->flags & ((1 << KEY_FLAG_INVALIDATED) |
956 (1 << KEY_FLAG_REVOKED))) {
957 kleave(" = NULL [x]");
961 kleave(" = {%d}", key->serial);
962 return make_key_ref(key, is_key_possessed(keyring_ref));
966 * Find a keyring with the specified name.
968 * All named keyrings in the current user namespace are searched, provided they
969 * grant Search permission directly to the caller (unless this check is
970 * skipped). Keyrings whose usage points have reached zero or who have been
971 * revoked are skipped.
973 * Returns a pointer to the keyring with the keyring's refcount having being
974 * incremented on success. -ENOKEY is returned if a key could not be found.
976 struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
982 return ERR_PTR(-EINVAL);
984 bucket = keyring_hash(name);
986 read_lock(&keyring_name_lock);
988 if (keyring_name_hash[bucket].next) {
989 /* search this hash bucket for a keyring with a matching name
990 * that's readable and that hasn't been revoked */
991 list_for_each_entry(keyring,
992 &keyring_name_hash[bucket],
995 if (!kuid_has_mapping(current_user_ns(), keyring->user->uid))
998 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1001 if (strcmp(keyring->description, name) != 0)
1004 if (!skip_perm_check &&
1005 key_permission(make_key_ref(keyring, 0),
1006 KEY_NEED_SEARCH) < 0)
1009 /* we've got a match but we might end up racing with
1010 * key_cleanup() if the keyring is currently 'dead'
1011 * (ie. it has a zero usage count) */
1012 if (!atomic_inc_not_zero(&keyring->usage))
1014 keyring->last_used_at = current_kernel_time().tv_sec;
1019 keyring = ERR_PTR(-ENOKEY);
1021 read_unlock(&keyring_name_lock);
1025 static int keyring_detect_cycle_iterator(const void *object,
1026 void *iterator_data)
1028 struct keyring_search_context *ctx = iterator_data;
1029 const struct key *key = keyring_ptr_to_key(object);
1031 kenter("{%d}", key->serial);
1033 /* We might get a keyring with matching index-key that is nonetheless a
1034 * different keyring. */
1035 if (key != ctx->match_data.raw_data)
1038 ctx->result = ERR_PTR(-EDEADLK);
1043 * See if a cycle will will be created by inserting acyclic tree B in acyclic
1044 * tree A at the topmost level (ie: as a direct child of A).
1046 * Since we are adding B to A at the top level, checking for cycles should just
1047 * be a matter of seeing if node A is somewhere in tree B.
1049 static int keyring_detect_cycle(struct key *A, struct key *B)
1051 struct keyring_search_context ctx = {
1052 .index_key = A->index_key,
1053 .match_data.raw_data = A,
1054 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
1055 .iterator = keyring_detect_cycle_iterator,
1056 .flags = (KEYRING_SEARCH_NO_STATE_CHECK |
1057 KEYRING_SEARCH_NO_UPDATE_TIME |
1058 KEYRING_SEARCH_NO_CHECK_PERM |
1059 KEYRING_SEARCH_DETECT_TOO_DEEP),
1063 search_nested_keyrings(B, &ctx);
1065 return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);
1069 * Preallocate memory so that a key can be linked into to a keyring.
1071 int __key_link_begin(struct key *keyring,
1072 const struct keyring_index_key *index_key,
1073 struct assoc_array_edit **_edit)
1074 __acquires(&keyring->sem)
1075 __acquires(&keyring_serialise_link_sem)
1077 struct assoc_array_edit *edit;
1081 keyring->serial, index_key->type->name, index_key->description);
1083 BUG_ON(index_key->desc_len == 0);
1085 if (keyring->type != &key_type_keyring)
1088 down_write(&keyring->sem);
1091 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1094 /* serialise link/link calls to prevent parallel calls causing a cycle
1095 * when linking two keyring in opposite orders */
1096 if (index_key->type == &key_type_keyring)
1097 down_write(&keyring_serialise_link_sem);
1099 /* Create an edit script that will insert/replace the key in the
1102 edit = assoc_array_insert(&keyring->keys,
1103 &keyring_assoc_array_ops,
1107 ret = PTR_ERR(edit);
1111 /* If we're not replacing a link in-place then we're going to need some
1114 if (!edit->dead_leaf) {
1115 ret = key_payload_reserve(keyring,
1116 keyring->datalen + KEYQUOTA_LINK_BYTES);
1126 assoc_array_cancel_edit(edit);
1128 if (index_key->type == &key_type_keyring)
1129 up_write(&keyring_serialise_link_sem);
1131 up_write(&keyring->sem);
1132 kleave(" = %d", ret);
1137 * Check already instantiated keys aren't going to be a problem.
1139 * The caller must have called __key_link_begin(). Don't need to call this for
1140 * keys that were created since __key_link_begin() was called.
1142 int __key_link_check_live_key(struct key *keyring, struct key *key)
1144 if (key->type == &key_type_keyring)
1145 /* check that we aren't going to create a cycle by linking one
1146 * keyring to another */
1147 return keyring_detect_cycle(keyring, key);
1152 * Link a key into to a keyring.
1154 * Must be called with __key_link_begin() having being called. Discards any
1155 * already extant link to matching key if there is one, so that each keyring
1156 * holds at most one link to any given key of a particular type+description
1159 void __key_link(struct key *key, struct assoc_array_edit **_edit)
1162 assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key));
1163 assoc_array_apply_edit(*_edit);
1168 * Finish linking a key into to a keyring.
1170 * Must be called with __key_link_begin() having being called.
1172 void __key_link_end(struct key *keyring,
1173 const struct keyring_index_key *index_key,
1174 struct assoc_array_edit *edit)
1175 __releases(&keyring->sem)
1176 __releases(&keyring_serialise_link_sem)
1178 BUG_ON(index_key->type == NULL);
1179 kenter("%d,%s,", keyring->serial, index_key->type->name);
1181 if (index_key->type == &key_type_keyring)
1182 up_write(&keyring_serialise_link_sem);
1185 if (!edit->dead_leaf) {
1186 key_payload_reserve(keyring,
1187 keyring->datalen - KEYQUOTA_LINK_BYTES);
1189 assoc_array_cancel_edit(edit);
1191 up_write(&keyring->sem);
1195 * key_link - Link a key to a keyring
1196 * @keyring: The keyring to make the link in.
1197 * @key: The key to link to.
1199 * Make a link in a keyring to a key, such that the keyring holds a reference
1200 * on that key and the key can potentially be found by searching that keyring.
1202 * This function will write-lock the keyring's semaphore and will consume some
1203 * of the user's key data quota to hold the link.
1205 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1206 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1207 * full, -EDQUOT if there is insufficient key data quota remaining to add
1208 * another link or -ENOMEM if there's insufficient memory.
1210 * It is assumed that the caller has checked that it is permitted for a link to
1211 * be made (the keyring should have Write permission and the key Link
1214 int key_link(struct key *keyring, struct key *key)
1216 struct assoc_array_edit *edit;
1219 kenter("{%d,%d}", keyring->serial, atomic_read(&keyring->usage));
1224 if (test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags) &&
1225 !test_bit(KEY_FLAG_TRUSTED, &key->flags))
1228 ret = __key_link_begin(keyring, &key->index_key, &edit);
1230 kdebug("begun {%d,%d}", keyring->serial, atomic_read(&keyring->usage));
1231 ret = __key_link_check_live_key(keyring, key);
1233 __key_link(key, &edit);
1234 __key_link_end(keyring, &key->index_key, edit);
1237 kleave(" = %d {%d,%d}", ret, keyring->serial, atomic_read(&keyring->usage));
1240 EXPORT_SYMBOL(key_link);
1243 * key_unlink - Unlink the first link to a key from a keyring.
1244 * @keyring: The keyring to remove the link from.
1245 * @key: The key the link is to.
1247 * Remove a link from a keyring to a key.
1249 * This function will write-lock the keyring's semaphore.
1251 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1252 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1255 * It is assumed that the caller has checked that it is permitted for a link to
1256 * be removed (the keyring should have Write permission; no permissions are
1257 * required on the key).
1259 int key_unlink(struct key *keyring, struct key *key)
1261 struct assoc_array_edit *edit;
1267 if (keyring->type != &key_type_keyring)
1270 down_write(&keyring->sem);
1272 edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
1275 ret = PTR_ERR(edit);
1282 assoc_array_apply_edit(edit);
1283 key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
1287 up_write(&keyring->sem);
1290 EXPORT_SYMBOL(key_unlink);
1293 * keyring_clear - Clear a keyring
1294 * @keyring: The keyring to clear.
1296 * Clear the contents of the specified keyring.
1298 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1300 int keyring_clear(struct key *keyring)
1302 struct assoc_array_edit *edit;
1305 if (keyring->type != &key_type_keyring)
1308 down_write(&keyring->sem);
1310 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1312 ret = PTR_ERR(edit);
1315 assoc_array_apply_edit(edit);
1316 key_payload_reserve(keyring, 0);
1320 up_write(&keyring->sem);
1323 EXPORT_SYMBOL(keyring_clear);
1326 * Dispose of the links from a revoked keyring.
1328 * This is called with the key sem write-locked.
1330 static void keyring_revoke(struct key *keyring)
1332 struct assoc_array_edit *edit;
1334 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1335 if (!IS_ERR(edit)) {
1337 assoc_array_apply_edit(edit);
1338 key_payload_reserve(keyring, 0);
1342 static bool keyring_gc_select_iterator(void *object, void *iterator_data)
1344 struct key *key = keyring_ptr_to_key(object);
1345 time_t *limit = iterator_data;
1347 if (key_is_dead(key, *limit))
1353 static int keyring_gc_check_iterator(const void *object, void *iterator_data)
1355 const struct key *key = keyring_ptr_to_key(object);
1356 time_t *limit = iterator_data;
1359 return key_is_dead(key, *limit);
1363 * Garbage collect pointers from a keyring.
1365 * Not called with any locks held. The keyring's key struct will not be
1366 * deallocated under us as only our caller may deallocate it.
1368 void keyring_gc(struct key *keyring, time_t limit)
1372 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1374 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
1375 (1 << KEY_FLAG_REVOKED)))
1378 /* scan the keyring looking for dead keys */
1380 result = assoc_array_iterate(&keyring->keys,
1381 keyring_gc_check_iterator, &limit);
1391 down_write(&keyring->sem);
1392 assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops,
1393 keyring_gc_select_iterator, &limit);
1394 up_write(&keyring->sem);