1 // SPDX-License-Identifier: GPL-2.0-or-later
4 * Copyright (C) 2004-2005, 2008, 2013 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
8 #include <linux/export.h>
9 #include <linux/init.h>
10 #include <linux/sched.h>
11 #include <linux/slab.h>
12 #include <linux/security.h>
13 #include <linux/seq_file.h>
14 #include <linux/err.h>
15 #include <keys/keyring-type.h>
16 #include <keys/user-type.h>
17 #include <linux/assoc_array_priv.h>
18 #include <linux/uaccess.h>
22 * When plumbing the depths of the key tree, this sets a hard limit
23 * set on how deep we're willing to go.
25 #define KEYRING_SEARCH_MAX_DEPTH 6
28 * We keep all named keyrings in a hash to speed looking them up.
30 #define KEYRING_NAME_HASH_SIZE (1 << 5)
33 * We mark pointers we pass to the associative array with bit 1 set if
34 * they're keyrings and clear otherwise.
36 #define KEYRING_PTR_SUBTYPE 0x2UL
38 static inline bool keyring_ptr_is_keyring(const struct assoc_array_ptr
*x
)
40 return (unsigned long)x
& KEYRING_PTR_SUBTYPE
;
42 static inline struct key
*keyring_ptr_to_key(const struct assoc_array_ptr
*x
)
44 void *object
= assoc_array_ptr_to_leaf(x
);
45 return (struct key
*)((unsigned long)object
& ~KEYRING_PTR_SUBTYPE
);
47 static inline void *keyring_key_to_ptr(struct key
*key
)
49 if (key
->type
== &key_type_keyring
)
50 return (void *)((unsigned long)key
| KEYRING_PTR_SUBTYPE
);
54 static struct list_head keyring_name_hash
[KEYRING_NAME_HASH_SIZE
];
55 static DEFINE_RWLOCK(keyring_name_lock
);
57 static inline unsigned keyring_hash(const char *desc
)
62 bucket
+= (unsigned char)*desc
;
64 return bucket
& (KEYRING_NAME_HASH_SIZE
- 1);
68 * The keyring key type definition. Keyrings are simply keys of this type and
69 * can be treated as ordinary keys in addition to having their own special
72 static int keyring_preparse(struct key_preparsed_payload
*prep
);
73 static void keyring_free_preparse(struct key_preparsed_payload
*prep
);
74 static int keyring_instantiate(struct key
*keyring
,
75 struct key_preparsed_payload
*prep
);
76 static void keyring_revoke(struct key
*keyring
);
77 static void keyring_destroy(struct key
*keyring
);
78 static void keyring_describe(const struct key
*keyring
, struct seq_file
*m
);
79 static long keyring_read(const struct key
*keyring
,
80 char __user
*buffer
, size_t buflen
);
82 struct key_type key_type_keyring
= {
85 .preparse
= keyring_preparse
,
86 .free_preparse
= keyring_free_preparse
,
87 .instantiate
= keyring_instantiate
,
88 .revoke
= keyring_revoke
,
89 .destroy
= keyring_destroy
,
90 .describe
= keyring_describe
,
93 EXPORT_SYMBOL(key_type_keyring
);
96 * Semaphore to serialise link/link calls to prevent two link calls in parallel
97 * introducing a cycle.
99 static DECLARE_RWSEM(keyring_serialise_link_sem
);
102 * Publish the name of a keyring so that it can be found by name (if it has
105 static void keyring_publish_name(struct key
*keyring
)
109 if (keyring
->description
) {
110 bucket
= keyring_hash(keyring
->description
);
112 write_lock(&keyring_name_lock
);
114 if (!keyring_name_hash
[bucket
].next
)
115 INIT_LIST_HEAD(&keyring_name_hash
[bucket
]);
117 list_add_tail(&keyring
->name_link
,
118 &keyring_name_hash
[bucket
]);
120 write_unlock(&keyring_name_lock
);
125 * Preparse a keyring payload
127 static int keyring_preparse(struct key_preparsed_payload
*prep
)
129 return prep
->datalen
!= 0 ? -EINVAL
: 0;
133 * Free a preparse of a user defined key payload
135 static void keyring_free_preparse(struct key_preparsed_payload
*prep
)
140 * Initialise a keyring.
142 * Returns 0 on success, -EINVAL if given any data.
144 static int keyring_instantiate(struct key
*keyring
,
145 struct key_preparsed_payload
*prep
)
147 assoc_array_init(&keyring
->keys
);
148 /* make the keyring available by name if it has one */
149 keyring_publish_name(keyring
);
154 * Multiply 64-bits by 32-bits to 96-bits and fold back to 64-bit. Ideally we'd
155 * fold the carry back too, but that requires inline asm.
157 static u64
mult_64x32_and_fold(u64 x
, u32 y
)
159 u64 hi
= (u64
)(u32
)(x
>> 32) * y
;
160 u64 lo
= (u64
)(u32
)(x
) * y
;
161 return lo
+ ((u64
)(u32
)hi
<< 32) + (u32
)(hi
>> 32);
165 * Hash a key type and description.
167 static unsigned long hash_key_type_and_desc(const struct keyring_index_key
*index_key
)
169 const unsigned level_shift
= ASSOC_ARRAY_LEVEL_STEP
;
170 const unsigned long fan_mask
= ASSOC_ARRAY_FAN_MASK
;
171 const char *description
= index_key
->description
;
172 unsigned long hash
, type
;
175 int n
, desc_len
= index_key
->desc_len
;
177 type
= (unsigned long)index_key
->type
;
179 acc
= mult_64x32_and_fold(type
, desc_len
+ 13);
180 acc
= mult_64x32_and_fold(acc
, 9207);
188 memcpy(&piece
, description
, n
);
191 acc
= mult_64x32_and_fold(acc
, piece
);
192 acc
= mult_64x32_and_fold(acc
, 9207);
195 /* Fold the hash down to 32 bits if need be. */
197 if (ASSOC_ARRAY_KEY_CHUNK_SIZE
== 32)
200 /* Squidge all the keyrings into a separate part of the tree to
201 * ordinary keys by making sure the lowest level segment in the hash is
202 * zero for keyrings and non-zero otherwise.
204 if (index_key
->type
!= &key_type_keyring
&& (hash
& fan_mask
) == 0)
205 return hash
| (hash
>> (ASSOC_ARRAY_KEY_CHUNK_SIZE
- level_shift
)) | 1;
206 if (index_key
->type
== &key_type_keyring
&& (hash
& fan_mask
) != 0)
207 return (hash
+ (hash
<< level_shift
)) & ~fan_mask
;
212 * Build the next index key chunk.
214 * On 32-bit systems the index key is laid out as:
217 * hash desclen typeptr desc[]
222 * hash desclen typeptr desc[]
224 * We return it one word-sized chunk at a time.
226 static unsigned long keyring_get_key_chunk(const void *data
, int level
)
228 const struct keyring_index_key
*index_key
= data
;
229 unsigned long chunk
= 0;
231 int desc_len
= index_key
->desc_len
, n
= sizeof(chunk
);
233 level
/= ASSOC_ARRAY_KEY_CHUNK_SIZE
;
236 return hash_key_type_and_desc(index_key
);
238 return ((unsigned long)index_key
->type
<< 8) | desc_len
;
241 return (u8
)((unsigned long)index_key
->type
>>
242 (ASSOC_ARRAY_KEY_CHUNK_SIZE
- 8));
247 offset
+= sizeof(chunk
) - 1;
248 offset
+= (level
- 3) * sizeof(chunk
);
249 if (offset
>= desc_len
)
257 chunk
|= ((u8
*)index_key
->description
)[--offset
];
258 } while (--desc_len
> 0);
262 chunk
|= (u8
)((unsigned long)index_key
->type
>>
263 (ASSOC_ARRAY_KEY_CHUNK_SIZE
- 8));
269 static unsigned long keyring_get_object_key_chunk(const void *object
, int level
)
271 const struct key
*key
= keyring_ptr_to_key(object
);
272 return keyring_get_key_chunk(&key
->index_key
, level
);
275 static bool keyring_compare_object(const void *object
, const void *data
)
277 const struct keyring_index_key
*index_key
= data
;
278 const struct key
*key
= keyring_ptr_to_key(object
);
280 return key
->index_key
.type
== index_key
->type
&&
281 key
->index_key
.desc_len
== index_key
->desc_len
&&
282 memcmp(key
->index_key
.description
, index_key
->description
,
283 index_key
->desc_len
) == 0;
287 * Compare the index keys of a pair of objects and determine the bit position
288 * at which they differ - if they differ.
290 static int keyring_diff_objects(const void *object
, const void *data
)
292 const struct key
*key_a
= keyring_ptr_to_key(object
);
293 const struct keyring_index_key
*a
= &key_a
->index_key
;
294 const struct keyring_index_key
*b
= data
;
295 unsigned long seg_a
, seg_b
;
299 seg_a
= hash_key_type_and_desc(a
);
300 seg_b
= hash_key_type_and_desc(b
);
301 if ((seg_a
^ seg_b
) != 0)
304 /* The number of bits contributed by the hash is controlled by a
305 * constant in the assoc_array headers. Everything else thereafter we
306 * can deal with as being machine word-size dependent.
308 level
+= ASSOC_ARRAY_KEY_CHUNK_SIZE
/ 8;
311 if ((seg_a
^ seg_b
) != 0)
314 /* The next bit may not work on big endian */
316 seg_a
= (unsigned long)a
->type
;
317 seg_b
= (unsigned long)b
->type
;
318 if ((seg_a
^ seg_b
) != 0)
321 level
+= sizeof(unsigned long);
322 if (a
->desc_len
== 0)
326 if (((unsigned long)a
->description
| (unsigned long)b
->description
) &
327 (sizeof(unsigned long) - 1)) {
329 seg_a
= *(unsigned long *)(a
->description
+ i
);
330 seg_b
= *(unsigned long *)(b
->description
+ i
);
331 if ((seg_a
^ seg_b
) != 0)
333 i
+= sizeof(unsigned long);
334 } while (i
< (a
->desc_len
& (sizeof(unsigned long) - 1)));
337 for (; i
< a
->desc_len
; i
++) {
338 seg_a
= *(unsigned char *)(a
->description
+ i
);
339 seg_b
= *(unsigned char *)(b
->description
+ i
);
340 if ((seg_a
^ seg_b
) != 0)
350 i
= level
* 8 + __ffs(seg_a
^ seg_b
);
355 * Free an object after stripping the keyring flag off of the pointer.
357 static void keyring_free_object(void *object
)
359 key_put(keyring_ptr_to_key(object
));
363 * Operations for keyring management by the index-tree routines.
365 static const struct assoc_array_ops keyring_assoc_array_ops
= {
366 .get_key_chunk
= keyring_get_key_chunk
,
367 .get_object_key_chunk
= keyring_get_object_key_chunk
,
368 .compare_object
= keyring_compare_object
,
369 .diff_objects
= keyring_diff_objects
,
370 .free_object
= keyring_free_object
,
374 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
375 * and dispose of its data.
377 * The garbage collector detects the final key_put(), removes the keyring from
378 * the serial number tree and then does RCU synchronisation before coming here,
379 * so we shouldn't need to worry about code poking around here with the RCU
380 * readlock held by this time.
382 static void keyring_destroy(struct key
*keyring
)
384 if (keyring
->description
) {
385 write_lock(&keyring_name_lock
);
387 if (keyring
->name_link
.next
!= NULL
&&
388 !list_empty(&keyring
->name_link
))
389 list_del(&keyring
->name_link
);
391 write_unlock(&keyring_name_lock
);
394 if (keyring
->restrict_link
) {
395 struct key_restriction
*keyres
= keyring
->restrict_link
;
397 key_put(keyres
->key
);
401 assoc_array_destroy(&keyring
->keys
, &keyring_assoc_array_ops
);
405 * Describe a keyring for /proc.
407 static void keyring_describe(const struct key
*keyring
, struct seq_file
*m
)
409 if (keyring
->description
)
410 seq_puts(m
, keyring
->description
);
412 seq_puts(m
, "[anon]");
414 if (key_is_positive(keyring
)) {
415 if (keyring
->keys
.nr_leaves_on_tree
!= 0)
416 seq_printf(m
, ": %lu", keyring
->keys
.nr_leaves_on_tree
);
418 seq_puts(m
, ": empty");
422 struct keyring_read_iterator_context
{
425 key_serial_t __user
*buffer
;
428 static int keyring_read_iterator(const void *object
, void *data
)
430 struct keyring_read_iterator_context
*ctx
= data
;
431 const struct key
*key
= keyring_ptr_to_key(object
);
434 kenter("{%s,%d},,{%zu/%zu}",
435 key
->type
->name
, key
->serial
, ctx
->count
, ctx
->buflen
);
437 if (ctx
->count
>= ctx
->buflen
)
440 ret
= put_user(key
->serial
, ctx
->buffer
);
444 ctx
->count
+= sizeof(key
->serial
);
449 * Read a list of key IDs from the keyring's contents in binary form
451 * The keyring's semaphore is read-locked by the caller. This prevents someone
452 * from modifying it under us - which could cause us to read key IDs multiple
455 static long keyring_read(const struct key
*keyring
,
456 char __user
*buffer
, size_t buflen
)
458 struct keyring_read_iterator_context ctx
;
461 kenter("{%d},,%zu", key_serial(keyring
), buflen
);
463 if (buflen
& (sizeof(key_serial_t
) - 1))
466 /* Copy as many key IDs as fit into the buffer */
467 if (buffer
&& buflen
) {
468 ctx
.buffer
= (key_serial_t __user
*)buffer
;
471 ret
= assoc_array_iterate(&keyring
->keys
,
472 keyring_read_iterator
, &ctx
);
474 kleave(" = %ld [iterate]", ret
);
479 /* Return the size of the buffer needed */
480 ret
= keyring
->keys
.nr_leaves_on_tree
* sizeof(key_serial_t
);
482 kleave("= %ld [ok]", ret
);
484 kleave("= %ld [buffer too small]", ret
);
489 * Allocate a keyring and link into the destination keyring.
491 struct key
*keyring_alloc(const char *description
, kuid_t uid
, kgid_t gid
,
492 const struct cred
*cred
, key_perm_t perm
,
494 struct key_restriction
*restrict_link
,
500 keyring
= key_alloc(&key_type_keyring
, description
,
501 uid
, gid
, cred
, perm
, flags
, restrict_link
);
502 if (!IS_ERR(keyring
)) {
503 ret
= key_instantiate_and_link(keyring
, NULL
, 0, dest
, NULL
);
506 keyring
= ERR_PTR(ret
);
512 EXPORT_SYMBOL(keyring_alloc
);
515 * restrict_link_reject - Give -EPERM to restrict link
516 * @keyring: The keyring being added to.
517 * @type: The type of key being added.
518 * @payload: The payload of the key intended to be added.
519 * @data: Additional data for evaluating restriction.
521 * Reject the addition of any links to a keyring. It can be overridden by
522 * passing KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when
523 * adding a key to a keyring.
525 * This is meant to be stored in a key_restriction structure which is passed
526 * in the restrict_link parameter to keyring_alloc().
528 int restrict_link_reject(struct key
*keyring
,
529 const struct key_type
*type
,
530 const union key_payload
*payload
,
531 struct key
*restriction_key
)
537 * By default, we keys found by getting an exact match on their descriptions.
539 bool key_default_cmp(const struct key
*key
,
540 const struct key_match_data
*match_data
)
542 return strcmp(key
->description
, match_data
->raw_data
) == 0;
546 * Iteration function to consider each key found.
548 static int keyring_search_iterator(const void *object
, void *iterator_data
)
550 struct keyring_search_context
*ctx
= iterator_data
;
551 const struct key
*key
= keyring_ptr_to_key(object
);
552 unsigned long kflags
= READ_ONCE(key
->flags
);
553 short state
= READ_ONCE(key
->state
);
555 kenter("{%d}", key
->serial
);
557 /* ignore keys not of this type */
558 if (key
->type
!= ctx
->index_key
.type
) {
559 kleave(" = 0 [!type]");
563 /* skip invalidated, revoked and expired keys */
564 if (ctx
->flags
& KEYRING_SEARCH_DO_STATE_CHECK
) {
565 time64_t expiry
= READ_ONCE(key
->expiry
);
567 if (kflags
& ((1 << KEY_FLAG_INVALIDATED
) |
568 (1 << KEY_FLAG_REVOKED
))) {
569 ctx
->result
= ERR_PTR(-EKEYREVOKED
);
570 kleave(" = %d [invrev]", ctx
->skipped_ret
);
574 if (expiry
&& ctx
->now
>= expiry
) {
575 if (!(ctx
->flags
& KEYRING_SEARCH_SKIP_EXPIRED
))
576 ctx
->result
= ERR_PTR(-EKEYEXPIRED
);
577 kleave(" = %d [expire]", ctx
->skipped_ret
);
582 /* keys that don't match */
583 if (!ctx
->match_data
.cmp(key
, &ctx
->match_data
)) {
584 kleave(" = 0 [!match]");
588 /* key must have search permissions */
589 if (!(ctx
->flags
& KEYRING_SEARCH_NO_CHECK_PERM
) &&
590 key_task_permission(make_key_ref(key
, ctx
->possessed
),
591 ctx
->cred
, KEY_NEED_SEARCH
) < 0) {
592 ctx
->result
= ERR_PTR(-EACCES
);
593 kleave(" = %d [!perm]", ctx
->skipped_ret
);
597 if (ctx
->flags
& KEYRING_SEARCH_DO_STATE_CHECK
) {
598 /* we set a different error code if we pass a negative key */
600 ctx
->result
= ERR_PTR(state
);
601 kleave(" = %d [neg]", ctx
->skipped_ret
);
607 ctx
->result
= make_key_ref(key
, ctx
->possessed
);
608 kleave(" = 1 [found]");
612 return ctx
->skipped_ret
;
616 * Search inside a keyring for a key. We can search by walking to it
617 * directly based on its index-key or we can iterate over the entire
618 * tree looking for it, based on the match function.
620 static int search_keyring(struct key
*keyring
, struct keyring_search_context
*ctx
)
622 if (ctx
->match_data
.lookup_type
== KEYRING_SEARCH_LOOKUP_DIRECT
) {
625 object
= assoc_array_find(&keyring
->keys
,
626 &keyring_assoc_array_ops
,
628 return object
? ctx
->iterator(object
, ctx
) : 0;
630 return assoc_array_iterate(&keyring
->keys
, ctx
->iterator
, ctx
);
634 * Search a tree of keyrings that point to other keyrings up to the maximum
637 static bool search_nested_keyrings(struct key
*keyring
,
638 struct keyring_search_context
*ctx
)
642 struct assoc_array_node
*node
;
644 } stack
[KEYRING_SEARCH_MAX_DEPTH
];
646 struct assoc_array_shortcut
*shortcut
;
647 struct assoc_array_node
*node
;
648 struct assoc_array_ptr
*ptr
;
652 kenter("{%d},{%s,%s}",
654 ctx
->index_key
.type
->name
,
655 ctx
->index_key
.description
);
657 #define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK)
658 BUG_ON((ctx
->flags
& STATE_CHECKS
) == 0 ||
659 (ctx
->flags
& STATE_CHECKS
) == STATE_CHECKS
);
661 /* Check to see if this top-level keyring is what we are looking for
662 * and whether it is valid or not.
664 if (ctx
->match_data
.lookup_type
== KEYRING_SEARCH_LOOKUP_ITERATE
||
665 keyring_compare_object(keyring
, &ctx
->index_key
)) {
666 ctx
->skipped_ret
= 2;
667 switch (ctx
->iterator(keyring_key_to_ptr(keyring
), ctx
)) {
677 ctx
->skipped_ret
= 0;
679 /* Start processing a new keyring */
681 kdebug("descend to %d", keyring
->serial
);
682 if (keyring
->flags
& ((1 << KEY_FLAG_INVALIDATED
) |
683 (1 << KEY_FLAG_REVOKED
)))
684 goto not_this_keyring
;
686 /* Search through the keys in this keyring before its searching its
689 if (search_keyring(keyring
, ctx
))
692 /* Then manually iterate through the keyrings nested in this one.
694 * Start from the root node of the index tree. Because of the way the
695 * hash function has been set up, keyrings cluster on the leftmost
696 * branch of the root node (root slot 0) or in the root node itself.
697 * Non-keyrings avoid the leftmost branch of the root entirely (root
700 ptr
= READ_ONCE(keyring
->keys
.root
);
702 goto not_this_keyring
;
704 if (assoc_array_ptr_is_shortcut(ptr
)) {
705 /* If the root is a shortcut, either the keyring only contains
706 * keyring pointers (everything clusters behind root slot 0) or
707 * doesn't contain any keyring pointers.
709 shortcut
= assoc_array_ptr_to_shortcut(ptr
);
710 if ((shortcut
->index_key
[0] & ASSOC_ARRAY_FAN_MASK
) != 0)
711 goto not_this_keyring
;
713 ptr
= READ_ONCE(shortcut
->next_node
);
714 node
= assoc_array_ptr_to_node(ptr
);
718 node
= assoc_array_ptr_to_node(ptr
);
719 ptr
= node
->slots
[0];
720 if (!assoc_array_ptr_is_meta(ptr
))
724 /* Descend to a more distal node in this keyring's content tree and go
728 if (assoc_array_ptr_is_shortcut(ptr
)) {
729 shortcut
= assoc_array_ptr_to_shortcut(ptr
);
730 ptr
= READ_ONCE(shortcut
->next_node
);
731 BUG_ON(!assoc_array_ptr_is_node(ptr
));
733 node
= assoc_array_ptr_to_node(ptr
);
736 kdebug("begin_node");
739 /* Go through the slots in a node */
740 for (; slot
< ASSOC_ARRAY_FAN_OUT
; slot
++) {
741 ptr
= READ_ONCE(node
->slots
[slot
]);
743 if (assoc_array_ptr_is_meta(ptr
) && node
->back_pointer
)
744 goto descend_to_node
;
746 if (!keyring_ptr_is_keyring(ptr
))
749 key
= keyring_ptr_to_key(ptr
);
751 if (sp
>= KEYRING_SEARCH_MAX_DEPTH
) {
752 if (ctx
->flags
& KEYRING_SEARCH_DETECT_TOO_DEEP
) {
753 ctx
->result
= ERR_PTR(-ELOOP
);
756 goto not_this_keyring
;
759 /* Search a nested keyring */
760 if (!(ctx
->flags
& KEYRING_SEARCH_NO_CHECK_PERM
) &&
761 key_task_permission(make_key_ref(key
, ctx
->possessed
),
762 ctx
->cred
, KEY_NEED_SEARCH
) < 0)
765 /* stack the current position */
766 stack
[sp
].keyring
= keyring
;
767 stack
[sp
].node
= node
;
768 stack
[sp
].slot
= slot
;
771 /* begin again with the new keyring */
773 goto descend_to_keyring
;
776 /* We've dealt with all the slots in the current node, so now we need
777 * to ascend to the parent and continue processing there.
779 ptr
= READ_ONCE(node
->back_pointer
);
780 slot
= node
->parent_slot
;
782 if (ptr
&& assoc_array_ptr_is_shortcut(ptr
)) {
783 shortcut
= assoc_array_ptr_to_shortcut(ptr
);
784 ptr
= READ_ONCE(shortcut
->back_pointer
);
785 slot
= shortcut
->parent_slot
;
788 goto not_this_keyring
;
789 node
= assoc_array_ptr_to_node(ptr
);
792 /* If we've ascended to the root (zero backpointer), we must have just
793 * finished processing the leftmost branch rather than the root slots -
794 * so there can't be any more keyrings for us to find.
796 if (node
->back_pointer
) {
797 kdebug("ascend %d", slot
);
801 /* The keyring we're looking at was disqualified or didn't contain a
805 kdebug("not_this_keyring %d", sp
);
811 /* Resume the processing of a keyring higher up in the tree */
813 keyring
= stack
[sp
].keyring
;
814 node
= stack
[sp
].node
;
815 slot
= stack
[sp
].slot
+ 1;
816 kdebug("ascend to %d [%d]", keyring
->serial
, slot
);
819 /* We found a viable match */
821 key
= key_ref_to_ptr(ctx
->result
);
823 if (!(ctx
->flags
& KEYRING_SEARCH_NO_UPDATE_TIME
)) {
824 key
->last_used_at
= ctx
->now
;
825 keyring
->last_used_at
= ctx
->now
;
827 stack
[--sp
].keyring
->last_used_at
= ctx
->now
;
834 * keyring_search_aux - Search a keyring tree for a key matching some criteria
835 * @keyring_ref: A pointer to the keyring with possession indicator.
836 * @ctx: The keyring search context.
838 * Search the supplied keyring tree for a key that matches the criteria given.
839 * The root keyring and any linked keyrings must grant Search permission to the
840 * caller to be searchable and keys can only be found if they too grant Search
841 * to the caller. The possession flag on the root keyring pointer controls use
842 * of the possessor bits in permissions checking of the entire tree. In
843 * addition, the LSM gets to forbid keyring searches and key matches.
845 * The search is performed as a breadth-then-depth search up to the prescribed
846 * limit (KEYRING_SEARCH_MAX_DEPTH).
848 * Keys are matched to the type provided and are then filtered by the match
849 * function, which is given the description to use in any way it sees fit. The
850 * match function may use any attributes of a key that it wishes to to
851 * determine the match. Normally the match function from the key type would be
854 * RCU can be used to prevent the keyring key lists from disappearing without
855 * the need to take lots of locks.
857 * Returns a pointer to the found key and increments the key usage count if
858 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
859 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
860 * specified keyring wasn't a keyring.
862 * In the case of a successful return, the possession attribute from
863 * @keyring_ref is propagated to the returned key reference.
865 key_ref_t
keyring_search_aux(key_ref_t keyring_ref
,
866 struct keyring_search_context
*ctx
)
871 ctx
->iterator
= keyring_search_iterator
;
872 ctx
->possessed
= is_key_possessed(keyring_ref
);
873 ctx
->result
= ERR_PTR(-EAGAIN
);
875 keyring
= key_ref_to_ptr(keyring_ref
);
878 if (keyring
->type
!= &key_type_keyring
)
879 return ERR_PTR(-ENOTDIR
);
881 if (!(ctx
->flags
& KEYRING_SEARCH_NO_CHECK_PERM
)) {
882 err
= key_task_permission(keyring_ref
, ctx
->cred
, KEY_NEED_SEARCH
);
888 ctx
->now
= ktime_get_real_seconds();
889 if (search_nested_keyrings(keyring
, ctx
))
890 __key_get(key_ref_to_ptr(ctx
->result
));
896 * keyring_search - Search the supplied keyring tree for a matching key
897 * @keyring: The root of the keyring tree to be searched.
898 * @type: The type of keyring we want to find.
899 * @description: The name of the keyring we want to find.
901 * As keyring_search_aux() above, but using the current task's credentials and
902 * type's default matching function and preferred search method.
904 key_ref_t
keyring_search(key_ref_t keyring
,
905 struct key_type
*type
,
906 const char *description
)
908 struct keyring_search_context ctx
= {
909 .index_key
.type
= type
,
910 .index_key
.description
= description
,
911 .index_key
.desc_len
= strlen(description
),
912 .cred
= current_cred(),
913 .match_data
.cmp
= key_default_cmp
,
914 .match_data
.raw_data
= description
,
915 .match_data
.lookup_type
= KEYRING_SEARCH_LOOKUP_DIRECT
,
916 .flags
= KEYRING_SEARCH_DO_STATE_CHECK
,
921 if (type
->match_preparse
) {
922 ret
= type
->match_preparse(&ctx
.match_data
);
927 key
= keyring_search_aux(keyring
, &ctx
);
929 if (type
->match_free
)
930 type
->match_free(&ctx
.match_data
);
933 EXPORT_SYMBOL(keyring_search
);
935 static struct key_restriction
*keyring_restriction_alloc(
936 key_restrict_link_func_t check
)
938 struct key_restriction
*keyres
=
939 kzalloc(sizeof(struct key_restriction
), GFP_KERNEL
);
942 return ERR_PTR(-ENOMEM
);
944 keyres
->check
= check
;
950 * Semaphore to serialise restriction setup to prevent reference count
951 * cycles through restriction key pointers.
953 static DECLARE_RWSEM(keyring_serialise_restrict_sem
);
956 * Check for restriction cycles that would prevent keyring garbage collection.
957 * keyring_serialise_restrict_sem must be held.
959 static bool keyring_detect_restriction_cycle(const struct key
*dest_keyring
,
960 struct key_restriction
*keyres
)
962 while (keyres
&& keyres
->key
&&
963 keyres
->key
->type
== &key_type_keyring
) {
964 if (keyres
->key
== dest_keyring
)
967 keyres
= keyres
->key
->restrict_link
;
974 * keyring_restrict - Look up and apply a restriction to a keyring
976 * @keyring: The keyring to be restricted
977 * @restriction: The restriction options to apply to the keyring
979 int keyring_restrict(key_ref_t keyring_ref
, const char *type
,
980 const char *restriction
)
983 struct key_type
*restrict_type
= NULL
;
984 struct key_restriction
*restrict_link
;
987 keyring
= key_ref_to_ptr(keyring_ref
);
990 if (keyring
->type
!= &key_type_keyring
)
994 restrict_link
= keyring_restriction_alloc(restrict_link_reject
);
996 restrict_type
= key_type_lookup(type
);
998 if (IS_ERR(restrict_type
))
999 return PTR_ERR(restrict_type
);
1001 if (!restrict_type
->lookup_restriction
) {
1006 restrict_link
= restrict_type
->lookup_restriction(restriction
);
1009 if (IS_ERR(restrict_link
)) {
1010 ret
= PTR_ERR(restrict_link
);
1014 down_write(&keyring
->sem
);
1015 down_write(&keyring_serialise_restrict_sem
);
1017 if (keyring
->restrict_link
)
1019 else if (keyring_detect_restriction_cycle(keyring
, restrict_link
))
1022 keyring
->restrict_link
= restrict_link
;
1024 up_write(&keyring_serialise_restrict_sem
);
1025 up_write(&keyring
->sem
);
1028 key_put(restrict_link
->key
);
1029 kfree(restrict_link
);
1034 key_type_put(restrict_type
);
1038 EXPORT_SYMBOL(keyring_restrict
);
1041 * Search the given keyring for a key that might be updated.
1043 * The caller must guarantee that the keyring is a keyring and that the
1044 * permission is granted to modify the keyring as no check is made here. The
1045 * caller must also hold a lock on the keyring semaphore.
1047 * Returns a pointer to the found key with usage count incremented if
1048 * successful and returns NULL if not found. Revoked and invalidated keys are
1051 * If successful, the possession indicator is propagated from the keyring ref
1052 * to the returned key reference.
1054 key_ref_t
find_key_to_update(key_ref_t keyring_ref
,
1055 const struct keyring_index_key
*index_key
)
1057 struct key
*keyring
, *key
;
1060 keyring
= key_ref_to_ptr(keyring_ref
);
1062 kenter("{%d},{%s,%s}",
1063 keyring
->serial
, index_key
->type
->name
, index_key
->description
);
1065 object
= assoc_array_find(&keyring
->keys
, &keyring_assoc_array_ops
,
1075 key
= keyring_ptr_to_key(object
);
1076 if (key
->flags
& ((1 << KEY_FLAG_INVALIDATED
) |
1077 (1 << KEY_FLAG_REVOKED
))) {
1078 kleave(" = NULL [x]");
1082 kleave(" = {%d}", key
->serial
);
1083 return make_key_ref(key
, is_key_possessed(keyring_ref
));
1087 * Find a keyring with the specified name.
1089 * Only keyrings that have nonzero refcount, are not revoked, and are owned by a
1090 * user in the current user namespace are considered. If @uid_keyring is %true,
1091 * the keyring additionally must have been allocated as a user or user session
1092 * keyring; otherwise, it must grant Search permission directly to the caller.
1094 * Returns a pointer to the keyring with the keyring's refcount having being
1095 * incremented on success. -ENOKEY is returned if a key could not be found.
1097 struct key
*find_keyring_by_name(const char *name
, bool uid_keyring
)
1099 struct key
*keyring
;
1103 return ERR_PTR(-EINVAL
);
1105 bucket
= keyring_hash(name
);
1107 read_lock(&keyring_name_lock
);
1109 if (keyring_name_hash
[bucket
].next
) {
1110 /* search this hash bucket for a keyring with a matching name
1111 * that's readable and that hasn't been revoked */
1112 list_for_each_entry(keyring
,
1113 &keyring_name_hash
[bucket
],
1116 if (!kuid_has_mapping(current_user_ns(), keyring
->user
->uid
))
1119 if (test_bit(KEY_FLAG_REVOKED
, &keyring
->flags
))
1122 if (strcmp(keyring
->description
, name
) != 0)
1126 if (!test_bit(KEY_FLAG_UID_KEYRING
,
1130 if (key_permission(make_key_ref(keyring
, 0),
1131 KEY_NEED_SEARCH
) < 0)
1135 /* we've got a match but we might end up racing with
1136 * key_cleanup() if the keyring is currently 'dead'
1137 * (ie. it has a zero usage count) */
1138 if (!refcount_inc_not_zero(&keyring
->usage
))
1140 keyring
->last_used_at
= ktime_get_real_seconds();
1145 keyring
= ERR_PTR(-ENOKEY
);
1147 read_unlock(&keyring_name_lock
);
1151 static int keyring_detect_cycle_iterator(const void *object
,
1152 void *iterator_data
)
1154 struct keyring_search_context
*ctx
= iterator_data
;
1155 const struct key
*key
= keyring_ptr_to_key(object
);
1157 kenter("{%d}", key
->serial
);
1159 /* We might get a keyring with matching index-key that is nonetheless a
1160 * different keyring. */
1161 if (key
!= ctx
->match_data
.raw_data
)
1164 ctx
->result
= ERR_PTR(-EDEADLK
);
1169 * See if a cycle will will be created by inserting acyclic tree B in acyclic
1170 * tree A at the topmost level (ie: as a direct child of A).
1172 * Since we are adding B to A at the top level, checking for cycles should just
1173 * be a matter of seeing if node A is somewhere in tree B.
1175 static int keyring_detect_cycle(struct key
*A
, struct key
*B
)
1177 struct keyring_search_context ctx
= {
1178 .index_key
= A
->index_key
,
1179 .match_data
.raw_data
= A
,
1180 .match_data
.lookup_type
= KEYRING_SEARCH_LOOKUP_DIRECT
,
1181 .iterator
= keyring_detect_cycle_iterator
,
1182 .flags
= (KEYRING_SEARCH_NO_STATE_CHECK
|
1183 KEYRING_SEARCH_NO_UPDATE_TIME
|
1184 KEYRING_SEARCH_NO_CHECK_PERM
|
1185 KEYRING_SEARCH_DETECT_TOO_DEEP
),
1189 search_nested_keyrings(B
, &ctx
);
1191 return PTR_ERR(ctx
.result
) == -EAGAIN
? 0 : PTR_ERR(ctx
.result
);
1195 * Preallocate memory so that a key can be linked into to a keyring.
1197 int __key_link_begin(struct key
*keyring
,
1198 const struct keyring_index_key
*index_key
,
1199 struct assoc_array_edit
**_edit
)
1200 __acquires(&keyring
->sem
)
1201 __acquires(&keyring_serialise_link_sem
)
1203 struct assoc_array_edit
*edit
;
1207 keyring
->serial
, index_key
->type
->name
, index_key
->description
);
1209 BUG_ON(index_key
->desc_len
== 0);
1211 if (keyring
->type
!= &key_type_keyring
)
1214 down_write(&keyring
->sem
);
1217 if (test_bit(KEY_FLAG_REVOKED
, &keyring
->flags
))
1220 /* serialise link/link calls to prevent parallel calls causing a cycle
1221 * when linking two keyring in opposite orders */
1222 if (index_key
->type
== &key_type_keyring
)
1223 down_write(&keyring_serialise_link_sem
);
1225 /* Create an edit script that will insert/replace the key in the
1228 edit
= assoc_array_insert(&keyring
->keys
,
1229 &keyring_assoc_array_ops
,
1233 ret
= PTR_ERR(edit
);
1237 /* If we're not replacing a link in-place then we're going to need some
1240 if (!edit
->dead_leaf
) {
1241 ret
= key_payload_reserve(keyring
,
1242 keyring
->datalen
+ KEYQUOTA_LINK_BYTES
);
1252 assoc_array_cancel_edit(edit
);
1254 if (index_key
->type
== &key_type_keyring
)
1255 up_write(&keyring_serialise_link_sem
);
1257 up_write(&keyring
->sem
);
1258 kleave(" = %d", ret
);
1263 * Check already instantiated keys aren't going to be a problem.
1265 * The caller must have called __key_link_begin(). Don't need to call this for
1266 * keys that were created since __key_link_begin() was called.
1268 int __key_link_check_live_key(struct key
*keyring
, struct key
*key
)
1270 if (key
->type
== &key_type_keyring
)
1271 /* check that we aren't going to create a cycle by linking one
1272 * keyring to another */
1273 return keyring_detect_cycle(keyring
, key
);
1278 * Link a key into to a keyring.
1280 * Must be called with __key_link_begin() having being called. Discards any
1281 * already extant link to matching key if there is one, so that each keyring
1282 * holds at most one link to any given key of a particular type+description
1285 void __key_link(struct key
*key
, struct assoc_array_edit
**_edit
)
1288 assoc_array_insert_set_object(*_edit
, keyring_key_to_ptr(key
));
1289 assoc_array_apply_edit(*_edit
);
1294 * Finish linking a key into to a keyring.
1296 * Must be called with __key_link_begin() having being called.
1298 void __key_link_end(struct key
*keyring
,
1299 const struct keyring_index_key
*index_key
,
1300 struct assoc_array_edit
*edit
)
1301 __releases(&keyring
->sem
)
1302 __releases(&keyring_serialise_link_sem
)
1304 BUG_ON(index_key
->type
== NULL
);
1305 kenter("%d,%s,", keyring
->serial
, index_key
->type
->name
);
1307 if (index_key
->type
== &key_type_keyring
)
1308 up_write(&keyring_serialise_link_sem
);
1311 if (!edit
->dead_leaf
) {
1312 key_payload_reserve(keyring
,
1313 keyring
->datalen
- KEYQUOTA_LINK_BYTES
);
1315 assoc_array_cancel_edit(edit
);
1317 up_write(&keyring
->sem
);
1321 * Check addition of keys to restricted keyrings.
1323 static int __key_link_check_restriction(struct key
*keyring
, struct key
*key
)
1325 if (!keyring
->restrict_link
|| !keyring
->restrict_link
->check
)
1327 return keyring
->restrict_link
->check(keyring
, key
->type
, &key
->payload
,
1328 keyring
->restrict_link
->key
);
1332 * key_link - Link a key to a keyring
1333 * @keyring: The keyring to make the link in.
1334 * @key: The key to link to.
1336 * Make a link in a keyring to a key, such that the keyring holds a reference
1337 * on that key and the key can potentially be found by searching that keyring.
1339 * This function will write-lock the keyring's semaphore and will consume some
1340 * of the user's key data quota to hold the link.
1342 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1343 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1344 * full, -EDQUOT if there is insufficient key data quota remaining to add
1345 * another link or -ENOMEM if there's insufficient memory.
1347 * It is assumed that the caller has checked that it is permitted for a link to
1348 * be made (the keyring should have Write permission and the key Link
1351 int key_link(struct key
*keyring
, struct key
*key
)
1353 struct assoc_array_edit
*edit
;
1356 kenter("{%d,%d}", keyring
->serial
, refcount_read(&keyring
->usage
));
1361 ret
= __key_link_begin(keyring
, &key
->index_key
, &edit
);
1363 kdebug("begun {%d,%d}", keyring
->serial
, refcount_read(&keyring
->usage
));
1364 ret
= __key_link_check_restriction(keyring
, key
);
1366 ret
= __key_link_check_live_key(keyring
, key
);
1368 __key_link(key
, &edit
);
1369 __key_link_end(keyring
, &key
->index_key
, edit
);
1372 kleave(" = %d {%d,%d}", ret
, keyring
->serial
, refcount_read(&keyring
->usage
));
1375 EXPORT_SYMBOL(key_link
);
1378 * key_unlink - Unlink the first link to a key from a keyring.
1379 * @keyring: The keyring to remove the link from.
1380 * @key: The key the link is to.
1382 * Remove a link from a keyring to a key.
1384 * This function will write-lock the keyring's semaphore.
1386 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1387 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1390 * It is assumed that the caller has checked that it is permitted for a link to
1391 * be removed (the keyring should have Write permission; no permissions are
1392 * required on the key).
1394 int key_unlink(struct key
*keyring
, struct key
*key
)
1396 struct assoc_array_edit
*edit
;
1402 if (keyring
->type
!= &key_type_keyring
)
1405 down_write(&keyring
->sem
);
1407 edit
= assoc_array_delete(&keyring
->keys
, &keyring_assoc_array_ops
,
1410 ret
= PTR_ERR(edit
);
1417 assoc_array_apply_edit(edit
);
1418 key_payload_reserve(keyring
, keyring
->datalen
- KEYQUOTA_LINK_BYTES
);
1422 up_write(&keyring
->sem
);
1425 EXPORT_SYMBOL(key_unlink
);
1428 * keyring_clear - Clear a keyring
1429 * @keyring: The keyring to clear.
1431 * Clear the contents of the specified keyring.
1433 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1435 int keyring_clear(struct key
*keyring
)
1437 struct assoc_array_edit
*edit
;
1440 if (keyring
->type
!= &key_type_keyring
)
1443 down_write(&keyring
->sem
);
1445 edit
= assoc_array_clear(&keyring
->keys
, &keyring_assoc_array_ops
);
1447 ret
= PTR_ERR(edit
);
1450 assoc_array_apply_edit(edit
);
1451 key_payload_reserve(keyring
, 0);
1455 up_write(&keyring
->sem
);
1458 EXPORT_SYMBOL(keyring_clear
);
1461 * Dispose of the links from a revoked keyring.
1463 * This is called with the key sem write-locked.
1465 static void keyring_revoke(struct key
*keyring
)
1467 struct assoc_array_edit
*edit
;
1469 edit
= assoc_array_clear(&keyring
->keys
, &keyring_assoc_array_ops
);
1470 if (!IS_ERR(edit
)) {
1472 assoc_array_apply_edit(edit
);
1473 key_payload_reserve(keyring
, 0);
1477 static bool keyring_gc_select_iterator(void *object
, void *iterator_data
)
1479 struct key
*key
= keyring_ptr_to_key(object
);
1480 time64_t
*limit
= iterator_data
;
1482 if (key_is_dead(key
, *limit
))
1488 static int keyring_gc_check_iterator(const void *object
, void *iterator_data
)
1490 const struct key
*key
= keyring_ptr_to_key(object
);
1491 time64_t
*limit
= iterator_data
;
1494 return key_is_dead(key
, *limit
);
1498 * Garbage collect pointers from a keyring.
1500 * Not called with any locks held. The keyring's key struct will not be
1501 * deallocated under us as only our caller may deallocate it.
1503 void keyring_gc(struct key
*keyring
, time64_t limit
)
1507 kenter("%x{%s}", keyring
->serial
, keyring
->description
?: "");
1509 if (keyring
->flags
& ((1 << KEY_FLAG_INVALIDATED
) |
1510 (1 << KEY_FLAG_REVOKED
)))
1513 /* scan the keyring looking for dead keys */
1515 result
= assoc_array_iterate(&keyring
->keys
,
1516 keyring_gc_check_iterator
, &limit
);
1526 down_write(&keyring
->sem
);
1527 assoc_array_gc(&keyring
->keys
, &keyring_assoc_array_ops
,
1528 keyring_gc_select_iterator
, &limit
);
1529 up_write(&keyring
->sem
);
1534 * Garbage collect restriction pointers from a keyring.
1536 * Keyring restrictions are associated with a key type, and must be cleaned
1537 * up if the key type is unregistered. The restriction is altered to always
1538 * reject additional keys so a keyring cannot be opened up by unregistering
1541 * Not called with any keyring locks held. The keyring's key struct will not
1542 * be deallocated under us as only our caller may deallocate it.
1544 * The caller is required to hold key_types_sem and dead_type->sem. This is
1545 * fulfilled by key_gc_keytype() holding the locks on behalf of
1546 * key_garbage_collector(), which it invokes on a workqueue.
1548 void keyring_restriction_gc(struct key
*keyring
, struct key_type
*dead_type
)
1550 struct key_restriction
*keyres
;
1552 kenter("%x{%s}", keyring
->serial
, keyring
->description
?: "");
1555 * keyring->restrict_link is only assigned at key allocation time
1556 * or with the key type locked, so the only values that could be
1557 * concurrently assigned to keyring->restrict_link are for key
1558 * types other than dead_type. Given this, it's ok to check
1559 * the key type before acquiring keyring->sem.
1561 if (!dead_type
|| !keyring
->restrict_link
||
1562 keyring
->restrict_link
->keytype
!= dead_type
) {
1563 kleave(" [no restriction gc]");
1567 /* Lock the keyring to ensure that a link is not in progress */
1568 down_write(&keyring
->sem
);
1570 keyres
= keyring
->restrict_link
;
1572 keyres
->check
= restrict_link_reject
;
1574 key_put(keyres
->key
);
1576 keyres
->keytype
= NULL
;
1578 up_write(&keyring
->sem
);
1580 kleave(" [restriction gc]");