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_positive(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->buflen);
433 if (ctx->count >= ctx->buflen)
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 if (!buffer || !buflen)
469 return nr_keys * sizeof(key_serial_t);
471 /* Copy the IDs of the subscribed keys into the buffer */
472 ctx.buffer = (key_serial_t __user *)buffer;
475 ret = assoc_array_iterate(&keyring->keys, keyring_read_iterator, &ctx);
477 kleave(" = %d [iterate]", ret);
481 kleave(" = %zu [ok]", ctx.count);
486 * Allocate a keyring and link into the destination keyring.
488 struct key *keyring_alloc(const char *description, kuid_t uid, kgid_t gid,
489 const struct cred *cred, key_perm_t perm,
490 unsigned long flags, struct key *dest)
495 keyring = key_alloc(&key_type_keyring, description,
496 uid, gid, cred, perm, flags);
497 if (!IS_ERR(keyring)) {
498 ret = key_instantiate_and_link(keyring, NULL, 0, dest, NULL);
501 keyring = ERR_PTR(ret);
507 EXPORT_SYMBOL(keyring_alloc);
510 * By default, we keys found by getting an exact match on their descriptions.
512 bool key_default_cmp(const struct key *key,
513 const struct key_match_data *match_data)
515 return strcmp(key->description, match_data->raw_data) == 0;
519 * Iteration function to consider each key found.
521 static int keyring_search_iterator(const void *object, void *iterator_data)
523 struct keyring_search_context *ctx = iterator_data;
524 const struct key *key = keyring_ptr_to_key(object);
525 unsigned long kflags = READ_ONCE(key->flags);
526 short state = READ_ONCE(key->state);
528 kenter("{%d}", key->serial);
530 /* ignore keys not of this type */
531 if (key->type != ctx->index_key.type) {
532 kleave(" = 0 [!type]");
536 /* skip invalidated, revoked and expired keys */
537 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
538 if (kflags & ((1 << KEY_FLAG_INVALIDATED) |
539 (1 << KEY_FLAG_REVOKED))) {
540 ctx->result = ERR_PTR(-EKEYREVOKED);
541 kleave(" = %d [invrev]", ctx->skipped_ret);
545 if (key->expiry && ctx->now.tv_sec >= key->expiry) {
546 if (!(ctx->flags & KEYRING_SEARCH_SKIP_EXPIRED))
547 ctx->result = ERR_PTR(-EKEYEXPIRED);
548 kleave(" = %d [expire]", ctx->skipped_ret);
553 /* keys that don't match */
554 if (!ctx->match_data.cmp(key, &ctx->match_data)) {
555 kleave(" = 0 [!match]");
559 /* key must have search permissions */
560 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
561 key_task_permission(make_key_ref(key, ctx->possessed),
562 ctx->cred, KEY_NEED_SEARCH) < 0) {
563 ctx->result = ERR_PTR(-EACCES);
564 kleave(" = %d [!perm]", ctx->skipped_ret);
568 if (ctx->flags & KEYRING_SEARCH_DO_STATE_CHECK) {
569 /* we set a different error code if we pass a negative key */
571 ctx->result = ERR_PTR(state);
572 kleave(" = %d [neg]", ctx->skipped_ret);
578 ctx->result = make_key_ref(key, ctx->possessed);
579 kleave(" = 1 [found]");
583 return ctx->skipped_ret;
587 * Search inside a keyring for a key. We can search by walking to it
588 * directly based on its index-key or we can iterate over the entire
589 * tree looking for it, based on the match function.
591 static int search_keyring(struct key *keyring, struct keyring_search_context *ctx)
593 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_DIRECT) {
596 object = assoc_array_find(&keyring->keys,
597 &keyring_assoc_array_ops,
599 return object ? ctx->iterator(object, ctx) : 0;
601 return assoc_array_iterate(&keyring->keys, ctx->iterator, ctx);
605 * Search a tree of keyrings that point to other keyrings up to the maximum
608 static bool search_nested_keyrings(struct key *keyring,
609 struct keyring_search_context *ctx)
613 struct assoc_array_node *node;
615 } stack[KEYRING_SEARCH_MAX_DEPTH];
617 struct assoc_array_shortcut *shortcut;
618 struct assoc_array_node *node;
619 struct assoc_array_ptr *ptr;
623 kenter("{%d},{%s,%s}",
625 ctx->index_key.type->name,
626 ctx->index_key.description);
628 #define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK)
629 BUG_ON((ctx->flags & STATE_CHECKS) == 0 ||
630 (ctx->flags & STATE_CHECKS) == STATE_CHECKS);
632 if (ctx->index_key.description)
633 ctx->index_key.desc_len = strlen(ctx->index_key.description);
635 /* Check to see if this top-level keyring is what we are looking for
636 * and whether it is valid or not.
638 if (ctx->match_data.lookup_type == KEYRING_SEARCH_LOOKUP_ITERATE ||
639 keyring_compare_object(keyring, &ctx->index_key)) {
640 ctx->skipped_ret = 2;
641 switch (ctx->iterator(keyring_key_to_ptr(keyring), ctx)) {
651 ctx->skipped_ret = 0;
653 /* Start processing a new keyring */
655 kdebug("descend to %d", keyring->serial);
656 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
657 (1 << KEY_FLAG_REVOKED)))
658 goto not_this_keyring;
660 /* Search through the keys in this keyring before its searching its
663 if (search_keyring(keyring, ctx))
666 /* Then manually iterate through the keyrings nested in this one.
668 * Start from the root node of the index tree. Because of the way the
669 * hash function has been set up, keyrings cluster on the leftmost
670 * branch of the root node (root slot 0) or in the root node itself.
671 * Non-keyrings avoid the leftmost branch of the root entirely (root
674 ptr = ACCESS_ONCE(keyring->keys.root);
676 goto not_this_keyring;
678 if (assoc_array_ptr_is_shortcut(ptr)) {
679 /* If the root is a shortcut, either the keyring only contains
680 * keyring pointers (everything clusters behind root slot 0) or
681 * doesn't contain any keyring pointers.
683 shortcut = assoc_array_ptr_to_shortcut(ptr);
684 smp_read_barrier_depends();
685 if ((shortcut->index_key[0] & ASSOC_ARRAY_FAN_MASK) != 0)
686 goto not_this_keyring;
688 ptr = ACCESS_ONCE(shortcut->next_node);
689 node = assoc_array_ptr_to_node(ptr);
693 node = assoc_array_ptr_to_node(ptr);
694 smp_read_barrier_depends();
696 ptr = node->slots[0];
697 if (!assoc_array_ptr_is_meta(ptr))
701 /* Descend to a more distal node in this keyring's content tree and go
705 if (assoc_array_ptr_is_shortcut(ptr)) {
706 shortcut = assoc_array_ptr_to_shortcut(ptr);
707 smp_read_barrier_depends();
708 ptr = ACCESS_ONCE(shortcut->next_node);
709 BUG_ON(!assoc_array_ptr_is_node(ptr));
711 node = assoc_array_ptr_to_node(ptr);
714 kdebug("begin_node");
715 smp_read_barrier_depends();
718 /* Go through the slots in a node */
719 for (; slot < ASSOC_ARRAY_FAN_OUT; slot++) {
720 ptr = ACCESS_ONCE(node->slots[slot]);
722 if (assoc_array_ptr_is_meta(ptr) && node->back_pointer)
723 goto descend_to_node;
725 if (!keyring_ptr_is_keyring(ptr))
728 key = keyring_ptr_to_key(ptr);
730 if (sp >= KEYRING_SEARCH_MAX_DEPTH) {
731 if (ctx->flags & KEYRING_SEARCH_DETECT_TOO_DEEP) {
732 ctx->result = ERR_PTR(-ELOOP);
735 goto not_this_keyring;
738 /* Search a nested keyring */
739 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM) &&
740 key_task_permission(make_key_ref(key, ctx->possessed),
741 ctx->cred, KEY_NEED_SEARCH) < 0)
744 /* stack the current position */
745 stack[sp].keyring = keyring;
746 stack[sp].node = node;
747 stack[sp].slot = slot;
750 /* begin again with the new keyring */
752 goto descend_to_keyring;
755 /* We've dealt with all the slots in the current node, so now we need
756 * to ascend to the parent and continue processing there.
758 ptr = ACCESS_ONCE(node->back_pointer);
759 slot = node->parent_slot;
761 if (ptr && assoc_array_ptr_is_shortcut(ptr)) {
762 shortcut = assoc_array_ptr_to_shortcut(ptr);
763 smp_read_barrier_depends();
764 ptr = ACCESS_ONCE(shortcut->back_pointer);
765 slot = shortcut->parent_slot;
768 goto not_this_keyring;
769 node = assoc_array_ptr_to_node(ptr);
770 smp_read_barrier_depends();
773 /* If we've ascended to the root (zero backpointer), we must have just
774 * finished processing the leftmost branch rather than the root slots -
775 * so there can't be any more keyrings for us to find.
777 if (node->back_pointer) {
778 kdebug("ascend %d", slot);
782 /* The keyring we're looking at was disqualified or didn't contain a
786 kdebug("not_this_keyring %d", sp);
792 /* Resume the processing of a keyring higher up in the tree */
794 keyring = stack[sp].keyring;
795 node = stack[sp].node;
796 slot = stack[sp].slot + 1;
797 kdebug("ascend to %d [%d]", keyring->serial, slot);
800 /* We found a viable match */
802 key = key_ref_to_ptr(ctx->result);
804 if (!(ctx->flags & KEYRING_SEARCH_NO_UPDATE_TIME)) {
805 key->last_used_at = ctx->now.tv_sec;
806 keyring->last_used_at = ctx->now.tv_sec;
808 stack[--sp].keyring->last_used_at = ctx->now.tv_sec;
815 * keyring_search_aux - Search a keyring tree for a key matching some criteria
816 * @keyring_ref: A pointer to the keyring with possession indicator.
817 * @ctx: The keyring search context.
819 * Search the supplied keyring tree for a key that matches the criteria given.
820 * The root keyring and any linked keyrings must grant Search permission to the
821 * caller to be searchable and keys can only be found if they too grant Search
822 * to the caller. The possession flag on the root keyring pointer controls use
823 * of the possessor bits in permissions checking of the entire tree. In
824 * addition, the LSM gets to forbid keyring searches and key matches.
826 * The search is performed as a breadth-then-depth search up to the prescribed
827 * limit (KEYRING_SEARCH_MAX_DEPTH).
829 * Keys are matched to the type provided and are then filtered by the match
830 * function, which is given the description to use in any way it sees fit. The
831 * match function may use any attributes of a key that it wishes to to
832 * determine the match. Normally the match function from the key type would be
835 * RCU can be used to prevent the keyring key lists from disappearing without
836 * the need to take lots of locks.
838 * Returns a pointer to the found key and increments the key usage count if
839 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
840 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
841 * specified keyring wasn't a keyring.
843 * In the case of a successful return, the possession attribute from
844 * @keyring_ref is propagated to the returned key reference.
846 key_ref_t keyring_search_aux(key_ref_t keyring_ref,
847 struct keyring_search_context *ctx)
852 ctx->iterator = keyring_search_iterator;
853 ctx->possessed = is_key_possessed(keyring_ref);
854 ctx->result = ERR_PTR(-EAGAIN);
856 keyring = key_ref_to_ptr(keyring_ref);
859 if (keyring->type != &key_type_keyring)
860 return ERR_PTR(-ENOTDIR);
862 if (!(ctx->flags & KEYRING_SEARCH_NO_CHECK_PERM)) {
863 err = key_task_permission(keyring_ref, ctx->cred, KEY_NEED_SEARCH);
869 ctx->now = current_kernel_time();
870 if (search_nested_keyrings(keyring, ctx))
871 __key_get(key_ref_to_ptr(ctx->result));
877 * keyring_search - Search the supplied keyring tree for a matching key
878 * @keyring: The root of the keyring tree to be searched.
879 * @type: The type of keyring we want to find.
880 * @description: The name of the keyring we want to find.
882 * As keyring_search_aux() above, but using the current task's credentials and
883 * type's default matching function and preferred search method.
885 key_ref_t keyring_search(key_ref_t keyring,
886 struct key_type *type,
887 const char *description)
889 struct keyring_search_context ctx = {
890 .index_key.type = type,
891 .index_key.description = description,
892 .cred = current_cred(),
893 .match_data.cmp = key_default_cmp,
894 .match_data.raw_data = description,
895 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
896 .flags = KEYRING_SEARCH_DO_STATE_CHECK,
901 if (type->match_preparse) {
902 ret = type->match_preparse(&ctx.match_data);
907 key = keyring_search_aux(keyring, &ctx);
909 if (type->match_free)
910 type->match_free(&ctx.match_data);
913 EXPORT_SYMBOL(keyring_search);
916 * Search the given keyring for a key that might be updated.
918 * The caller must guarantee that the keyring is a keyring and that the
919 * permission is granted to modify the keyring as no check is made here. The
920 * caller must also hold a lock on the keyring semaphore.
922 * Returns a pointer to the found key with usage count incremented if
923 * successful and returns NULL if not found. Revoked and invalidated keys are
926 * If successful, the possession indicator is propagated from the keyring ref
927 * to the returned key reference.
929 key_ref_t find_key_to_update(key_ref_t keyring_ref,
930 const struct keyring_index_key *index_key)
932 struct key *keyring, *key;
935 keyring = key_ref_to_ptr(keyring_ref);
937 kenter("{%d},{%s,%s}",
938 keyring->serial, index_key->type->name, index_key->description);
940 object = assoc_array_find(&keyring->keys, &keyring_assoc_array_ops,
950 key = keyring_ptr_to_key(object);
951 if (key->flags & ((1 << KEY_FLAG_INVALIDATED) |
952 (1 << KEY_FLAG_REVOKED))) {
953 kleave(" = NULL [x]");
957 kleave(" = {%d}", key->serial);
958 return make_key_ref(key, is_key_possessed(keyring_ref));
962 * Find a keyring with the specified name.
964 * Only keyrings that have nonzero refcount, are not revoked, and are owned by a
965 * user in the current user namespace are considered. If @uid_keyring is %true,
966 * the keyring additionally must have been allocated as a user or user session
967 * keyring; otherwise, it must grant Search permission directly to the caller.
969 * Returns a pointer to the keyring with the keyring's refcount having being
970 * incremented on success. -ENOKEY is returned if a key could not be found.
972 struct key *find_keyring_by_name(const char *name, bool uid_keyring)
978 return ERR_PTR(-EINVAL);
980 bucket = keyring_hash(name);
982 read_lock(&keyring_name_lock);
984 if (keyring_name_hash[bucket].next) {
985 /* search this hash bucket for a keyring with a matching name
986 * that's readable and that hasn't been revoked */
987 list_for_each_entry(keyring,
988 &keyring_name_hash[bucket],
991 if (!kuid_has_mapping(current_user_ns(), keyring->user->uid))
994 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
997 if (strcmp(keyring->description, name) != 0)
1001 if (!test_bit(KEY_FLAG_UID_KEYRING,
1005 if (key_permission(make_key_ref(keyring, 0),
1006 KEY_NEED_SEARCH) < 0)
1010 /* we've got a match but we might end up racing with
1011 * key_cleanup() if the keyring is currently 'dead'
1012 * (ie. it has a zero usage count) */
1013 if (!atomic_inc_not_zero(&keyring->usage))
1015 keyring->last_used_at = current_kernel_time().tv_sec;
1020 keyring = ERR_PTR(-ENOKEY);
1022 read_unlock(&keyring_name_lock);
1026 static int keyring_detect_cycle_iterator(const void *object,
1027 void *iterator_data)
1029 struct keyring_search_context *ctx = iterator_data;
1030 const struct key *key = keyring_ptr_to_key(object);
1032 kenter("{%d}", key->serial);
1034 /* We might get a keyring with matching index-key that is nonetheless a
1035 * different keyring. */
1036 if (key != ctx->match_data.raw_data)
1039 ctx->result = ERR_PTR(-EDEADLK);
1044 * See if a cycle will will be created by inserting acyclic tree B in acyclic
1045 * tree A at the topmost level (ie: as a direct child of A).
1047 * Since we are adding B to A at the top level, checking for cycles should just
1048 * be a matter of seeing if node A is somewhere in tree B.
1050 static int keyring_detect_cycle(struct key *A, struct key *B)
1052 struct keyring_search_context ctx = {
1053 .index_key = A->index_key,
1054 .match_data.raw_data = A,
1055 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
1056 .iterator = keyring_detect_cycle_iterator,
1057 .flags = (KEYRING_SEARCH_NO_STATE_CHECK |
1058 KEYRING_SEARCH_NO_UPDATE_TIME |
1059 KEYRING_SEARCH_NO_CHECK_PERM |
1060 KEYRING_SEARCH_DETECT_TOO_DEEP),
1064 search_nested_keyrings(B, &ctx);
1066 return PTR_ERR(ctx.result) == -EAGAIN ? 0 : PTR_ERR(ctx.result);
1070 * Preallocate memory so that a key can be linked into to a keyring.
1072 int __key_link_begin(struct key *keyring,
1073 const struct keyring_index_key *index_key,
1074 struct assoc_array_edit **_edit)
1075 __acquires(&keyring->sem)
1076 __acquires(&keyring_serialise_link_sem)
1078 struct assoc_array_edit *edit;
1082 keyring->serial, index_key->type->name, index_key->description);
1084 BUG_ON(index_key->desc_len == 0);
1086 if (keyring->type != &key_type_keyring)
1089 down_write(&keyring->sem);
1092 if (test_bit(KEY_FLAG_REVOKED, &keyring->flags))
1095 /* serialise link/link calls to prevent parallel calls causing a cycle
1096 * when linking two keyring in opposite orders */
1097 if (index_key->type == &key_type_keyring)
1098 down_write(&keyring_serialise_link_sem);
1100 /* Create an edit script that will insert/replace the key in the
1103 edit = assoc_array_insert(&keyring->keys,
1104 &keyring_assoc_array_ops,
1108 ret = PTR_ERR(edit);
1112 /* If we're not replacing a link in-place then we're going to need some
1115 if (!edit->dead_leaf) {
1116 ret = key_payload_reserve(keyring,
1117 keyring->datalen + KEYQUOTA_LINK_BYTES);
1127 assoc_array_cancel_edit(edit);
1129 if (index_key->type == &key_type_keyring)
1130 up_write(&keyring_serialise_link_sem);
1132 up_write(&keyring->sem);
1133 kleave(" = %d", ret);
1138 * Check already instantiated keys aren't going to be a problem.
1140 * The caller must have called __key_link_begin(). Don't need to call this for
1141 * keys that were created since __key_link_begin() was called.
1143 int __key_link_check_live_key(struct key *keyring, struct key *key)
1145 if (key->type == &key_type_keyring)
1146 /* check that we aren't going to create a cycle by linking one
1147 * keyring to another */
1148 return keyring_detect_cycle(keyring, key);
1153 * Link a key into to a keyring.
1155 * Must be called with __key_link_begin() having being called. Discards any
1156 * already extant link to matching key if there is one, so that each keyring
1157 * holds at most one link to any given key of a particular type+description
1160 void __key_link(struct key *key, struct assoc_array_edit **_edit)
1163 assoc_array_insert_set_object(*_edit, keyring_key_to_ptr(key));
1164 assoc_array_apply_edit(*_edit);
1169 * Finish linking a key into to a keyring.
1171 * Must be called with __key_link_begin() having being called.
1173 void __key_link_end(struct key *keyring,
1174 const struct keyring_index_key *index_key,
1175 struct assoc_array_edit *edit)
1176 __releases(&keyring->sem)
1177 __releases(&keyring_serialise_link_sem)
1179 BUG_ON(index_key->type == NULL);
1180 kenter("%d,%s,", keyring->serial, index_key->type->name);
1182 if (index_key->type == &key_type_keyring)
1183 up_write(&keyring_serialise_link_sem);
1186 if (!edit->dead_leaf) {
1187 key_payload_reserve(keyring,
1188 keyring->datalen - KEYQUOTA_LINK_BYTES);
1190 assoc_array_cancel_edit(edit);
1192 up_write(&keyring->sem);
1196 * key_link - Link a key to a keyring
1197 * @keyring: The keyring to make the link in.
1198 * @key: The key to link to.
1200 * Make a link in a keyring to a key, such that the keyring holds a reference
1201 * on that key and the key can potentially be found by searching that keyring.
1203 * This function will write-lock the keyring's semaphore and will consume some
1204 * of the user's key data quota to hold the link.
1206 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1207 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1208 * full, -EDQUOT if there is insufficient key data quota remaining to add
1209 * another link or -ENOMEM if there's insufficient memory.
1211 * It is assumed that the caller has checked that it is permitted for a link to
1212 * be made (the keyring should have Write permission and the key Link
1215 int key_link(struct key *keyring, struct key *key)
1217 struct assoc_array_edit *edit;
1220 kenter("{%d,%d}", keyring->serial, atomic_read(&keyring->usage));
1225 if (test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags) &&
1226 !test_bit(KEY_FLAG_TRUSTED, &key->flags))
1229 ret = __key_link_begin(keyring, &key->index_key, &edit);
1231 kdebug("begun {%d,%d}", keyring->serial, atomic_read(&keyring->usage));
1232 ret = __key_link_check_live_key(keyring, key);
1234 __key_link(key, &edit);
1235 __key_link_end(keyring, &key->index_key, edit);
1238 kleave(" = %d {%d,%d}", ret, keyring->serial, atomic_read(&keyring->usage));
1241 EXPORT_SYMBOL(key_link);
1244 * key_unlink - Unlink the first link to a key from a keyring.
1245 * @keyring: The keyring to remove the link from.
1246 * @key: The key the link is to.
1248 * Remove a link from a keyring to a key.
1250 * This function will write-lock the keyring's semaphore.
1252 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1253 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1256 * It is assumed that the caller has checked that it is permitted for a link to
1257 * be removed (the keyring should have Write permission; no permissions are
1258 * required on the key).
1260 int key_unlink(struct key *keyring, struct key *key)
1262 struct assoc_array_edit *edit;
1268 if (keyring->type != &key_type_keyring)
1271 down_write(&keyring->sem);
1273 edit = assoc_array_delete(&keyring->keys, &keyring_assoc_array_ops,
1276 ret = PTR_ERR(edit);
1283 assoc_array_apply_edit(edit);
1284 key_payload_reserve(keyring, keyring->datalen - KEYQUOTA_LINK_BYTES);
1288 up_write(&keyring->sem);
1291 EXPORT_SYMBOL(key_unlink);
1294 * keyring_clear - Clear a keyring
1295 * @keyring: The keyring to clear.
1297 * Clear the contents of the specified keyring.
1299 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1301 int keyring_clear(struct key *keyring)
1303 struct assoc_array_edit *edit;
1306 if (keyring->type != &key_type_keyring)
1309 down_write(&keyring->sem);
1311 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1313 ret = PTR_ERR(edit);
1316 assoc_array_apply_edit(edit);
1317 key_payload_reserve(keyring, 0);
1321 up_write(&keyring->sem);
1324 EXPORT_SYMBOL(keyring_clear);
1327 * Dispose of the links from a revoked keyring.
1329 * This is called with the key sem write-locked.
1331 static void keyring_revoke(struct key *keyring)
1333 struct assoc_array_edit *edit;
1335 edit = assoc_array_clear(&keyring->keys, &keyring_assoc_array_ops);
1336 if (!IS_ERR(edit)) {
1338 assoc_array_apply_edit(edit);
1339 key_payload_reserve(keyring, 0);
1343 static bool keyring_gc_select_iterator(void *object, void *iterator_data)
1345 struct key *key = keyring_ptr_to_key(object);
1346 time_t *limit = iterator_data;
1348 if (key_is_dead(key, *limit))
1354 static int keyring_gc_check_iterator(const void *object, void *iterator_data)
1356 const struct key *key = keyring_ptr_to_key(object);
1357 time_t *limit = iterator_data;
1360 return key_is_dead(key, *limit);
1364 * Garbage collect pointers from a keyring.
1366 * Not called with any locks held. The keyring's key struct will not be
1367 * deallocated under us as only our caller may deallocate it.
1369 void keyring_gc(struct key *keyring, time_t limit)
1373 kenter("%x{%s}", keyring->serial, keyring->description ?: "");
1375 if (keyring->flags & ((1 << KEY_FLAG_INVALIDATED) |
1376 (1 << KEY_FLAG_REVOKED)))
1379 /* scan the keyring looking for dead keys */
1381 result = assoc_array_iterate(&keyring->keys,
1382 keyring_gc_check_iterator, &limit);
1392 down_write(&keyring->sem);
1393 assoc_array_gc(&keyring->keys, &keyring_assoc_array_ops,
1394 keyring_gc_select_iterator, &limit);
1395 up_write(&keyring->sem);