3 * Copyright (C) 2004-2005, 2008, 2013 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
12 #include <linux/export.h>
13 #include <linux/init.h>
14 #include <linux/sched.h>
15 #include <linux/slab.h>
16 #include <linux/security.h>
17 #include <linux/seq_file.h>
18 #include <linux/err.h>
19 #include <keys/keyring-type.h>
20 #include <keys/user-type.h>
21 #include <linux/assoc_array_priv.h>
22 #include <linux/uaccess.h>
26 * When plumbing the depths of the key tree, this sets a hard limit
27 * set on how deep we're willing to go.
29 #define KEYRING_SEARCH_MAX_DEPTH 6
32 * We keep all named keyrings in a hash to speed looking them up.
34 #define KEYRING_NAME_HASH_SIZE (1 << 5)
37 * We mark pointers we pass to the associative array with bit 1 set if
38 * they're keyrings and clear otherwise.
40 #define KEYRING_PTR_SUBTYPE 0x2UL
42 static inline bool keyring_ptr_is_keyring(const struct assoc_array_ptr
*x
)
44 return (unsigned long)x
& KEYRING_PTR_SUBTYPE
;
46 static inline struct key
*keyring_ptr_to_key(const struct assoc_array_ptr
*x
)
48 void *object
= assoc_array_ptr_to_leaf(x
);
49 return (struct key
*)((unsigned long)object
& ~KEYRING_PTR_SUBTYPE
);
51 static inline void *keyring_key_to_ptr(struct key
*key
)
53 if (key
->type
== &key_type_keyring
)
54 return (void *)((unsigned long)key
| KEYRING_PTR_SUBTYPE
);
58 static struct list_head keyring_name_hash
[KEYRING_NAME_HASH_SIZE
];
59 static DEFINE_RWLOCK(keyring_name_lock
);
61 static inline unsigned keyring_hash(const char *desc
)
66 bucket
+= (unsigned char)*desc
;
68 return bucket
& (KEYRING_NAME_HASH_SIZE
- 1);
72 * The keyring key type definition. Keyrings are simply keys of this type and
73 * can be treated as ordinary keys in addition to having their own special
76 static int keyring_preparse(struct key_preparsed_payload
*prep
);
77 static void keyring_free_preparse(struct key_preparsed_payload
*prep
);
78 static int keyring_instantiate(struct key
*keyring
,
79 struct key_preparsed_payload
*prep
);
80 static void keyring_revoke(struct key
*keyring
);
81 static void keyring_destroy(struct key
*keyring
);
82 static void keyring_describe(const struct key
*keyring
, struct seq_file
*m
);
83 static long keyring_read(const struct key
*keyring
,
84 char __user
*buffer
, size_t buflen
);
86 struct key_type key_type_keyring
= {
89 .preparse
= keyring_preparse
,
90 .free_preparse
= keyring_free_preparse
,
91 .instantiate
= keyring_instantiate
,
92 .revoke
= keyring_revoke
,
93 .destroy
= keyring_destroy
,
94 .describe
= keyring_describe
,
97 EXPORT_SYMBOL(key_type_keyring
);
100 * Semaphore to serialise link/link calls to prevent two link calls in parallel
101 * introducing a cycle.
103 static DECLARE_RWSEM(keyring_serialise_link_sem
);
106 * Publish the name of a keyring so that it can be found by name (if it has
109 static void keyring_publish_name(struct key
*keyring
)
113 if (keyring
->description
) {
114 bucket
= keyring_hash(keyring
->description
);
116 write_lock(&keyring_name_lock
);
118 if (!keyring_name_hash
[bucket
].next
)
119 INIT_LIST_HEAD(&keyring_name_hash
[bucket
]);
121 list_add_tail(&keyring
->name_link
,
122 &keyring_name_hash
[bucket
]);
124 write_unlock(&keyring_name_lock
);
129 * Preparse a keyring payload
131 static int keyring_preparse(struct key_preparsed_payload
*prep
)
133 return prep
->datalen
!= 0 ? -EINVAL
: 0;
137 * Free a preparse of a user defined key payload
139 static void keyring_free_preparse(struct key_preparsed_payload
*prep
)
144 * Initialise a keyring.
146 * Returns 0 on success, -EINVAL if given any data.
148 static int keyring_instantiate(struct key
*keyring
,
149 struct key_preparsed_payload
*prep
)
151 assoc_array_init(&keyring
->keys
);
152 /* make the keyring available by name if it has one */
153 keyring_publish_name(keyring
);
158 * Multiply 64-bits by 32-bits to 96-bits and fold back to 64-bit. Ideally we'd
159 * fold the carry back too, but that requires inline asm.
161 static u64
mult_64x32_and_fold(u64 x
, u32 y
)
163 u64 hi
= (u64
)(u32
)(x
>> 32) * y
;
164 u64 lo
= (u64
)(u32
)(x
) * y
;
165 return lo
+ ((u64
)(u32
)hi
<< 32) + (u32
)(hi
>> 32);
169 * Hash a key type and description.
171 static unsigned long hash_key_type_and_desc(const struct keyring_index_key
*index_key
)
173 const unsigned level_shift
= ASSOC_ARRAY_LEVEL_STEP
;
174 const unsigned long fan_mask
= ASSOC_ARRAY_FAN_MASK
;
175 const char *description
= index_key
->description
;
176 unsigned long hash
, type
;
179 int n
, desc_len
= index_key
->desc_len
;
181 type
= (unsigned long)index_key
->type
;
183 acc
= mult_64x32_and_fold(type
, desc_len
+ 13);
184 acc
= mult_64x32_and_fold(acc
, 9207);
192 memcpy(&piece
, description
, n
);
195 acc
= mult_64x32_and_fold(acc
, piece
);
196 acc
= mult_64x32_and_fold(acc
, 9207);
199 /* Fold the hash down to 32 bits if need be. */
201 if (ASSOC_ARRAY_KEY_CHUNK_SIZE
== 32)
204 /* Squidge all the keyrings into a separate part of the tree to
205 * ordinary keys by making sure the lowest level segment in the hash is
206 * zero for keyrings and non-zero otherwise.
208 if (index_key
->type
!= &key_type_keyring
&& (hash
& fan_mask
) == 0)
209 return hash
| (hash
>> (ASSOC_ARRAY_KEY_CHUNK_SIZE
- level_shift
)) | 1;
210 if (index_key
->type
== &key_type_keyring
&& (hash
& fan_mask
) != 0)
211 return (hash
+ (hash
<< level_shift
)) & ~fan_mask
;
216 * Build the next index key chunk.
218 * On 32-bit systems the index key is laid out as:
221 * hash desclen typeptr desc[]
226 * hash desclen typeptr desc[]
228 * We return it one word-sized chunk at a time.
230 static unsigned long keyring_get_key_chunk(const void *data
, int level
)
232 const struct keyring_index_key
*index_key
= data
;
233 unsigned long chunk
= 0;
235 int desc_len
= index_key
->desc_len
, n
= sizeof(chunk
);
237 level
/= ASSOC_ARRAY_KEY_CHUNK_SIZE
;
240 return hash_key_type_and_desc(index_key
);
242 return ((unsigned long)index_key
->type
<< 8) | desc_len
;
245 return (u8
)((unsigned long)index_key
->type
>>
246 (ASSOC_ARRAY_KEY_CHUNK_SIZE
- 8));
251 offset
+= sizeof(chunk
) - 1;
252 offset
+= (level
- 3) * sizeof(chunk
);
253 if (offset
>= desc_len
)
261 chunk
|= ((u8
*)index_key
->description
)[--offset
];
262 } while (--desc_len
> 0);
266 chunk
|= (u8
)((unsigned long)index_key
->type
>>
267 (ASSOC_ARRAY_KEY_CHUNK_SIZE
- 8));
273 static unsigned long keyring_get_object_key_chunk(const void *object
, int level
)
275 const struct key
*key
= keyring_ptr_to_key(object
);
276 return keyring_get_key_chunk(&key
->index_key
, level
);
279 static bool keyring_compare_object(const void *object
, const void *data
)
281 const struct keyring_index_key
*index_key
= data
;
282 const struct key
*key
= keyring_ptr_to_key(object
);
284 return key
->index_key
.type
== index_key
->type
&&
285 key
->index_key
.desc_len
== index_key
->desc_len
&&
286 memcmp(key
->index_key
.description
, index_key
->description
,
287 index_key
->desc_len
) == 0;
291 * Compare the index keys of a pair of objects and determine the bit position
292 * at which they differ - if they differ.
294 static int keyring_diff_objects(const void *object
, const void *data
)
296 const struct key
*key_a
= keyring_ptr_to_key(object
);
297 const struct keyring_index_key
*a
= &key_a
->index_key
;
298 const struct keyring_index_key
*b
= data
;
299 unsigned long seg_a
, seg_b
;
303 seg_a
= hash_key_type_and_desc(a
);
304 seg_b
= hash_key_type_and_desc(b
);
305 if ((seg_a
^ seg_b
) != 0)
308 /* The number of bits contributed by the hash is controlled by a
309 * constant in the assoc_array headers. Everything else thereafter we
310 * can deal with as being machine word-size dependent.
312 level
+= ASSOC_ARRAY_KEY_CHUNK_SIZE
/ 8;
315 if ((seg_a
^ seg_b
) != 0)
318 /* The next bit may not work on big endian */
320 seg_a
= (unsigned long)a
->type
;
321 seg_b
= (unsigned long)b
->type
;
322 if ((seg_a
^ seg_b
) != 0)
325 level
+= sizeof(unsigned long);
326 if (a
->desc_len
== 0)
330 if (((unsigned long)a
->description
| (unsigned long)b
->description
) &
331 (sizeof(unsigned long) - 1)) {
333 seg_a
= *(unsigned long *)(a
->description
+ i
);
334 seg_b
= *(unsigned long *)(b
->description
+ i
);
335 if ((seg_a
^ seg_b
) != 0)
337 i
+= sizeof(unsigned long);
338 } while (i
< (a
->desc_len
& (sizeof(unsigned long) - 1)));
341 for (; i
< a
->desc_len
; i
++) {
342 seg_a
= *(unsigned char *)(a
->description
+ i
);
343 seg_b
= *(unsigned char *)(b
->description
+ i
);
344 if ((seg_a
^ seg_b
) != 0)
354 i
= level
* 8 + __ffs(seg_a
^ seg_b
);
359 * Free an object after stripping the keyring flag off of the pointer.
361 static void keyring_free_object(void *object
)
363 key_put(keyring_ptr_to_key(object
));
367 * Operations for keyring management by the index-tree routines.
369 static const struct assoc_array_ops keyring_assoc_array_ops
= {
370 .get_key_chunk
= keyring_get_key_chunk
,
371 .get_object_key_chunk
= keyring_get_object_key_chunk
,
372 .compare_object
= keyring_compare_object
,
373 .diff_objects
= keyring_diff_objects
,
374 .free_object
= keyring_free_object
,
378 * Clean up a keyring when it is destroyed. Unpublish its name if it had one
379 * and dispose of its data.
381 * The garbage collector detects the final key_put(), removes the keyring from
382 * the serial number tree and then does RCU synchronisation before coming here,
383 * so we shouldn't need to worry about code poking around here with the RCU
384 * readlock held by this time.
386 static void keyring_destroy(struct key
*keyring
)
388 if (keyring
->description
) {
389 write_lock(&keyring_name_lock
);
391 if (keyring
->name_link
.next
!= NULL
&&
392 !list_empty(&keyring
->name_link
))
393 list_del(&keyring
->name_link
);
395 write_unlock(&keyring_name_lock
);
398 if (keyring
->restrict_link
) {
399 struct key_restriction
*keyres
= keyring
->restrict_link
;
401 key_put(keyres
->key
);
405 assoc_array_destroy(&keyring
->keys
, &keyring_assoc_array_ops
);
409 * Describe a keyring for /proc.
411 static void keyring_describe(const struct key
*keyring
, struct seq_file
*m
)
413 if (keyring
->description
)
414 seq_puts(m
, keyring
->description
);
416 seq_puts(m
, "[anon]");
418 if (key_is_positive(keyring
)) {
419 if (keyring
->keys
.nr_leaves_on_tree
!= 0)
420 seq_printf(m
, ": %lu", keyring
->keys
.nr_leaves_on_tree
);
422 seq_puts(m
, ": empty");
426 struct keyring_read_iterator_context
{
429 key_serial_t __user
*buffer
;
432 static int keyring_read_iterator(const void *object
, void *data
)
434 struct keyring_read_iterator_context
*ctx
= data
;
435 const struct key
*key
= keyring_ptr_to_key(object
);
438 kenter("{%s,%d},,{%zu/%zu}",
439 key
->type
->name
, key
->serial
, ctx
->count
, ctx
->buflen
);
441 if (ctx
->count
>= ctx
->buflen
)
444 ret
= put_user(key
->serial
, ctx
->buffer
);
448 ctx
->count
+= sizeof(key
->serial
);
453 * Read a list of key IDs from the keyring's contents in binary form
455 * The keyring's semaphore is read-locked by the caller. This prevents someone
456 * from modifying it under us - which could cause us to read key IDs multiple
459 static long keyring_read(const struct key
*keyring
,
460 char __user
*buffer
, size_t buflen
)
462 struct keyring_read_iterator_context ctx
;
465 kenter("{%d},,%zu", key_serial(keyring
), buflen
);
467 if (buflen
& (sizeof(key_serial_t
) - 1))
470 /* Copy as many key IDs as fit into the buffer */
471 if (buffer
&& buflen
) {
472 ctx
.buffer
= (key_serial_t __user
*)buffer
;
475 ret
= assoc_array_iterate(&keyring
->keys
,
476 keyring_read_iterator
, &ctx
);
478 kleave(" = %ld [iterate]", ret
);
483 /* Return the size of the buffer needed */
484 ret
= keyring
->keys
.nr_leaves_on_tree
* sizeof(key_serial_t
);
486 kleave("= %ld [ok]", ret
);
488 kleave("= %ld [buffer too small]", ret
);
493 * Allocate a keyring and link into the destination keyring.
495 struct key
*keyring_alloc(const char *description
, kuid_t uid
, kgid_t gid
,
496 const struct cred
*cred
, key_perm_t perm
,
498 struct key_restriction
*restrict_link
,
504 keyring
= key_alloc(&key_type_keyring
, description
,
505 uid
, gid
, cred
, perm
, flags
, restrict_link
);
506 if (!IS_ERR(keyring
)) {
507 ret
= key_instantiate_and_link(keyring
, NULL
, 0, dest
, NULL
);
510 keyring
= ERR_PTR(ret
);
516 EXPORT_SYMBOL(keyring_alloc
);
519 * restrict_link_reject - Give -EPERM to restrict link
520 * @keyring: The keyring being added to.
521 * @type: The type of key being added.
522 * @payload: The payload of the key intended to be added.
523 * @data: Additional data for evaluating restriction.
525 * Reject the addition of any links to a keyring. It can be overridden by
526 * passing KEY_ALLOC_BYPASS_RESTRICTION to key_instantiate_and_link() when
527 * adding a key to a keyring.
529 * This is meant to be stored in a key_restriction structure which is passed
530 * in the restrict_link parameter to keyring_alloc().
532 int restrict_link_reject(struct key
*keyring
,
533 const struct key_type
*type
,
534 const union key_payload
*payload
,
535 struct key
*restriction_key
)
541 * By default, we keys found by getting an exact match on their descriptions.
543 bool key_default_cmp(const struct key
*key
,
544 const struct key_match_data
*match_data
)
546 return strcmp(key
->description
, match_data
->raw_data
) == 0;
550 * Iteration function to consider each key found.
552 static int keyring_search_iterator(const void *object
, void *iterator_data
)
554 struct keyring_search_context
*ctx
= iterator_data
;
555 const struct key
*key
= keyring_ptr_to_key(object
);
556 unsigned long kflags
= READ_ONCE(key
->flags
);
557 short state
= READ_ONCE(key
->state
);
559 kenter("{%d}", key
->serial
);
561 /* ignore keys not of this type */
562 if (key
->type
!= ctx
->index_key
.type
) {
563 kleave(" = 0 [!type]");
567 /* skip invalidated, revoked and expired keys */
568 if (ctx
->flags
& KEYRING_SEARCH_DO_STATE_CHECK
) {
569 time64_t expiry
= READ_ONCE(key
->expiry
);
571 if (kflags
& ((1 << KEY_FLAG_INVALIDATED
) |
572 (1 << KEY_FLAG_REVOKED
))) {
573 ctx
->result
= ERR_PTR(-EKEYREVOKED
);
574 kleave(" = %d [invrev]", ctx
->skipped_ret
);
578 if (expiry
&& ctx
->now
>= expiry
) {
579 if (!(ctx
->flags
& KEYRING_SEARCH_SKIP_EXPIRED
))
580 ctx
->result
= ERR_PTR(-EKEYEXPIRED
);
581 kleave(" = %d [expire]", ctx
->skipped_ret
);
586 /* keys that don't match */
587 if (!ctx
->match_data
.cmp(key
, &ctx
->match_data
)) {
588 kleave(" = 0 [!match]");
592 /* key must have search permissions */
593 if (!(ctx
->flags
& KEYRING_SEARCH_NO_CHECK_PERM
) &&
594 key_task_permission(make_key_ref(key
, ctx
->possessed
),
595 ctx
->cred
, KEY_NEED_SEARCH
) < 0) {
596 ctx
->result
= ERR_PTR(-EACCES
);
597 kleave(" = %d [!perm]", ctx
->skipped_ret
);
601 if (ctx
->flags
& KEYRING_SEARCH_DO_STATE_CHECK
) {
602 /* we set a different error code if we pass a negative key */
604 ctx
->result
= ERR_PTR(state
);
605 kleave(" = %d [neg]", ctx
->skipped_ret
);
611 ctx
->result
= make_key_ref(key
, ctx
->possessed
);
612 kleave(" = 1 [found]");
616 return ctx
->skipped_ret
;
620 * Search inside a keyring for a key. We can search by walking to it
621 * directly based on its index-key or we can iterate over the entire
622 * tree looking for it, based on the match function.
624 static int search_keyring(struct key
*keyring
, struct keyring_search_context
*ctx
)
626 if (ctx
->match_data
.lookup_type
== KEYRING_SEARCH_LOOKUP_DIRECT
) {
629 object
= assoc_array_find(&keyring
->keys
,
630 &keyring_assoc_array_ops
,
632 return object
? ctx
->iterator(object
, ctx
) : 0;
634 return assoc_array_iterate(&keyring
->keys
, ctx
->iterator
, ctx
);
638 * Search a tree of keyrings that point to other keyrings up to the maximum
641 static bool search_nested_keyrings(struct key
*keyring
,
642 struct keyring_search_context
*ctx
)
646 struct assoc_array_node
*node
;
648 } stack
[KEYRING_SEARCH_MAX_DEPTH
];
650 struct assoc_array_shortcut
*shortcut
;
651 struct assoc_array_node
*node
;
652 struct assoc_array_ptr
*ptr
;
656 kenter("{%d},{%s,%s}",
658 ctx
->index_key
.type
->name
,
659 ctx
->index_key
.description
);
661 #define STATE_CHECKS (KEYRING_SEARCH_NO_STATE_CHECK | KEYRING_SEARCH_DO_STATE_CHECK)
662 BUG_ON((ctx
->flags
& STATE_CHECKS
) == 0 ||
663 (ctx
->flags
& STATE_CHECKS
) == STATE_CHECKS
);
665 /* Check to see if this top-level keyring is what we are looking for
666 * and whether it is valid or not.
668 if (ctx
->match_data
.lookup_type
== KEYRING_SEARCH_LOOKUP_ITERATE
||
669 keyring_compare_object(keyring
, &ctx
->index_key
)) {
670 ctx
->skipped_ret
= 2;
671 switch (ctx
->iterator(keyring_key_to_ptr(keyring
), ctx
)) {
681 ctx
->skipped_ret
= 0;
683 /* Start processing a new keyring */
685 kdebug("descend to %d", keyring
->serial
);
686 if (keyring
->flags
& ((1 << KEY_FLAG_INVALIDATED
) |
687 (1 << KEY_FLAG_REVOKED
)))
688 goto not_this_keyring
;
690 /* Search through the keys in this keyring before its searching its
693 if (search_keyring(keyring
, ctx
))
696 /* Then manually iterate through the keyrings nested in this one.
698 * Start from the root node of the index tree. Because of the way the
699 * hash function has been set up, keyrings cluster on the leftmost
700 * branch of the root node (root slot 0) or in the root node itself.
701 * Non-keyrings avoid the leftmost branch of the root entirely (root
704 ptr
= READ_ONCE(keyring
->keys
.root
);
706 goto not_this_keyring
;
708 if (assoc_array_ptr_is_shortcut(ptr
)) {
709 /* If the root is a shortcut, either the keyring only contains
710 * keyring pointers (everything clusters behind root slot 0) or
711 * doesn't contain any keyring pointers.
713 shortcut
= assoc_array_ptr_to_shortcut(ptr
);
714 if ((shortcut
->index_key
[0] & ASSOC_ARRAY_FAN_MASK
) != 0)
715 goto not_this_keyring
;
717 ptr
= READ_ONCE(shortcut
->next_node
);
718 node
= assoc_array_ptr_to_node(ptr
);
722 node
= assoc_array_ptr_to_node(ptr
);
723 ptr
= node
->slots
[0];
724 if (!assoc_array_ptr_is_meta(ptr
))
728 /* Descend to a more distal node in this keyring's content tree and go
732 if (assoc_array_ptr_is_shortcut(ptr
)) {
733 shortcut
= assoc_array_ptr_to_shortcut(ptr
);
734 ptr
= READ_ONCE(shortcut
->next_node
);
735 BUG_ON(!assoc_array_ptr_is_node(ptr
));
737 node
= assoc_array_ptr_to_node(ptr
);
740 kdebug("begin_node");
743 /* Go through the slots in a node */
744 for (; slot
< ASSOC_ARRAY_FAN_OUT
; slot
++) {
745 ptr
= READ_ONCE(node
->slots
[slot
]);
747 if (assoc_array_ptr_is_meta(ptr
) && node
->back_pointer
)
748 goto descend_to_node
;
750 if (!keyring_ptr_is_keyring(ptr
))
753 key
= keyring_ptr_to_key(ptr
);
755 if (sp
>= KEYRING_SEARCH_MAX_DEPTH
) {
756 if (ctx
->flags
& KEYRING_SEARCH_DETECT_TOO_DEEP
) {
757 ctx
->result
= ERR_PTR(-ELOOP
);
760 goto not_this_keyring
;
763 /* Search a nested keyring */
764 if (!(ctx
->flags
& KEYRING_SEARCH_NO_CHECK_PERM
) &&
765 key_task_permission(make_key_ref(key
, ctx
->possessed
),
766 ctx
->cred
, KEY_NEED_SEARCH
) < 0)
769 /* stack the current position */
770 stack
[sp
].keyring
= keyring
;
771 stack
[sp
].node
= node
;
772 stack
[sp
].slot
= slot
;
775 /* begin again with the new keyring */
777 goto descend_to_keyring
;
780 /* We've dealt with all the slots in the current node, so now we need
781 * to ascend to the parent and continue processing there.
783 ptr
= READ_ONCE(node
->back_pointer
);
784 slot
= node
->parent_slot
;
786 if (ptr
&& assoc_array_ptr_is_shortcut(ptr
)) {
787 shortcut
= assoc_array_ptr_to_shortcut(ptr
);
788 ptr
= READ_ONCE(shortcut
->back_pointer
);
789 slot
= shortcut
->parent_slot
;
792 goto not_this_keyring
;
793 node
= assoc_array_ptr_to_node(ptr
);
796 /* If we've ascended to the root (zero backpointer), we must have just
797 * finished processing the leftmost branch rather than the root slots -
798 * so there can't be any more keyrings for us to find.
800 if (node
->back_pointer
) {
801 kdebug("ascend %d", slot
);
805 /* The keyring we're looking at was disqualified or didn't contain a
809 kdebug("not_this_keyring %d", sp
);
815 /* Resume the processing of a keyring higher up in the tree */
817 keyring
= stack
[sp
].keyring
;
818 node
= stack
[sp
].node
;
819 slot
= stack
[sp
].slot
+ 1;
820 kdebug("ascend to %d [%d]", keyring
->serial
, slot
);
823 /* We found a viable match */
825 key
= key_ref_to_ptr(ctx
->result
);
827 if (!(ctx
->flags
& KEYRING_SEARCH_NO_UPDATE_TIME
)) {
828 key
->last_used_at
= ctx
->now
;
829 keyring
->last_used_at
= ctx
->now
;
831 stack
[--sp
].keyring
->last_used_at
= ctx
->now
;
838 * keyring_search_aux - Search a keyring tree for a key matching some criteria
839 * @keyring_ref: A pointer to the keyring with possession indicator.
840 * @ctx: The keyring search context.
842 * Search the supplied keyring tree for a key that matches the criteria given.
843 * The root keyring and any linked keyrings must grant Search permission to the
844 * caller to be searchable and keys can only be found if they too grant Search
845 * to the caller. The possession flag on the root keyring pointer controls use
846 * of the possessor bits in permissions checking of the entire tree. In
847 * addition, the LSM gets to forbid keyring searches and key matches.
849 * The search is performed as a breadth-then-depth search up to the prescribed
850 * limit (KEYRING_SEARCH_MAX_DEPTH).
852 * Keys are matched to the type provided and are then filtered by the match
853 * function, which is given the description to use in any way it sees fit. The
854 * match function may use any attributes of a key that it wishes to to
855 * determine the match. Normally the match function from the key type would be
858 * RCU can be used to prevent the keyring key lists from disappearing without
859 * the need to take lots of locks.
861 * Returns a pointer to the found key and increments the key usage count if
862 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
863 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
864 * specified keyring wasn't a keyring.
866 * In the case of a successful return, the possession attribute from
867 * @keyring_ref is propagated to the returned key reference.
869 key_ref_t
keyring_search_aux(key_ref_t keyring_ref
,
870 struct keyring_search_context
*ctx
)
875 ctx
->iterator
= keyring_search_iterator
;
876 ctx
->possessed
= is_key_possessed(keyring_ref
);
877 ctx
->result
= ERR_PTR(-EAGAIN
);
879 keyring
= key_ref_to_ptr(keyring_ref
);
882 if (keyring
->type
!= &key_type_keyring
)
883 return ERR_PTR(-ENOTDIR
);
885 if (!(ctx
->flags
& KEYRING_SEARCH_NO_CHECK_PERM
)) {
886 err
= key_task_permission(keyring_ref
, ctx
->cred
, KEY_NEED_SEARCH
);
892 ctx
->now
= ktime_get_real_seconds();
893 if (search_nested_keyrings(keyring
, ctx
))
894 __key_get(key_ref_to_ptr(ctx
->result
));
900 * keyring_search - Search the supplied keyring tree for a matching key
901 * @keyring: The root of the keyring tree to be searched.
902 * @type: The type of keyring we want to find.
903 * @description: The name of the keyring we want to find.
905 * As keyring_search_aux() above, but using the current task's credentials and
906 * type's default matching function and preferred search method.
908 key_ref_t
keyring_search(key_ref_t keyring
,
909 struct key_type
*type
,
910 const char *description
)
912 struct keyring_search_context ctx
= {
913 .index_key
.type
= type
,
914 .index_key
.description
= description
,
915 .index_key
.desc_len
= strlen(description
),
916 .cred
= current_cred(),
917 .match_data
.cmp
= key_default_cmp
,
918 .match_data
.raw_data
= description
,
919 .match_data
.lookup_type
= KEYRING_SEARCH_LOOKUP_DIRECT
,
920 .flags
= KEYRING_SEARCH_DO_STATE_CHECK
,
925 if (type
->match_preparse
) {
926 ret
= type
->match_preparse(&ctx
.match_data
);
931 key
= keyring_search_aux(keyring
, &ctx
);
933 if (type
->match_free
)
934 type
->match_free(&ctx
.match_data
);
937 EXPORT_SYMBOL(keyring_search
);
939 static struct key_restriction
*keyring_restriction_alloc(
940 key_restrict_link_func_t check
)
942 struct key_restriction
*keyres
=
943 kzalloc(sizeof(struct key_restriction
), GFP_KERNEL
);
946 return ERR_PTR(-ENOMEM
);
948 keyres
->check
= check
;
954 * Semaphore to serialise restriction setup to prevent reference count
955 * cycles through restriction key pointers.
957 static DECLARE_RWSEM(keyring_serialise_restrict_sem
);
960 * Check for restriction cycles that would prevent keyring garbage collection.
961 * keyring_serialise_restrict_sem must be held.
963 static bool keyring_detect_restriction_cycle(const struct key
*dest_keyring
,
964 struct key_restriction
*keyres
)
966 while (keyres
&& keyres
->key
&&
967 keyres
->key
->type
== &key_type_keyring
) {
968 if (keyres
->key
== dest_keyring
)
971 keyres
= keyres
->key
->restrict_link
;
978 * keyring_restrict - Look up and apply a restriction to a keyring
980 * @keyring: The keyring to be restricted
981 * @restriction: The restriction options to apply to the keyring
983 int keyring_restrict(key_ref_t keyring_ref
, const char *type
,
984 const char *restriction
)
987 struct key_type
*restrict_type
= NULL
;
988 struct key_restriction
*restrict_link
;
991 keyring
= key_ref_to_ptr(keyring_ref
);
994 if (keyring
->type
!= &key_type_keyring
)
998 restrict_link
= keyring_restriction_alloc(restrict_link_reject
);
1000 restrict_type
= key_type_lookup(type
);
1002 if (IS_ERR(restrict_type
))
1003 return PTR_ERR(restrict_type
);
1005 if (!restrict_type
->lookup_restriction
) {
1010 restrict_link
= restrict_type
->lookup_restriction(restriction
);
1013 if (IS_ERR(restrict_link
)) {
1014 ret
= PTR_ERR(restrict_link
);
1018 down_write(&keyring
->sem
);
1019 down_write(&keyring_serialise_restrict_sem
);
1021 if (keyring
->restrict_link
)
1023 else if (keyring_detect_restriction_cycle(keyring
, restrict_link
))
1026 keyring
->restrict_link
= restrict_link
;
1028 up_write(&keyring_serialise_restrict_sem
);
1029 up_write(&keyring
->sem
);
1032 key_put(restrict_link
->key
);
1033 kfree(restrict_link
);
1038 key_type_put(restrict_type
);
1042 EXPORT_SYMBOL(keyring_restrict
);
1045 * Search the given keyring for a key that might be updated.
1047 * The caller must guarantee that the keyring is a keyring and that the
1048 * permission is granted to modify the keyring as no check is made here. The
1049 * caller must also hold a lock on the keyring semaphore.
1051 * Returns a pointer to the found key with usage count incremented if
1052 * successful and returns NULL if not found. Revoked and invalidated keys are
1055 * If successful, the possession indicator is propagated from the keyring ref
1056 * to the returned key reference.
1058 key_ref_t
find_key_to_update(key_ref_t keyring_ref
,
1059 const struct keyring_index_key
*index_key
)
1061 struct key
*keyring
, *key
;
1064 keyring
= key_ref_to_ptr(keyring_ref
);
1066 kenter("{%d},{%s,%s}",
1067 keyring
->serial
, index_key
->type
->name
, index_key
->description
);
1069 object
= assoc_array_find(&keyring
->keys
, &keyring_assoc_array_ops
,
1079 key
= keyring_ptr_to_key(object
);
1080 if (key
->flags
& ((1 << KEY_FLAG_INVALIDATED
) |
1081 (1 << KEY_FLAG_REVOKED
))) {
1082 kleave(" = NULL [x]");
1086 kleave(" = {%d}", key
->serial
);
1087 return make_key_ref(key
, is_key_possessed(keyring_ref
));
1091 * Find a keyring with the specified name.
1093 * Only keyrings that have nonzero refcount, are not revoked, and are owned by a
1094 * user in the current user namespace are considered. If @uid_keyring is %true,
1095 * the keyring additionally must have been allocated as a user or user session
1096 * keyring; otherwise, it must grant Search permission directly to the caller.
1098 * Returns a pointer to the keyring with the keyring's refcount having being
1099 * incremented on success. -ENOKEY is returned if a key could not be found.
1101 struct key
*find_keyring_by_name(const char *name
, bool uid_keyring
)
1103 struct key
*keyring
;
1107 return ERR_PTR(-EINVAL
);
1109 bucket
= keyring_hash(name
);
1111 read_lock(&keyring_name_lock
);
1113 if (keyring_name_hash
[bucket
].next
) {
1114 /* search this hash bucket for a keyring with a matching name
1115 * that's readable and that hasn't been revoked */
1116 list_for_each_entry(keyring
,
1117 &keyring_name_hash
[bucket
],
1120 if (!kuid_has_mapping(current_user_ns(), keyring
->user
->uid
))
1123 if (test_bit(KEY_FLAG_REVOKED
, &keyring
->flags
))
1126 if (strcmp(keyring
->description
, name
) != 0)
1130 if (!test_bit(KEY_FLAG_UID_KEYRING
,
1134 if (key_permission(make_key_ref(keyring
, 0),
1135 KEY_NEED_SEARCH
) < 0)
1139 /* we've got a match but we might end up racing with
1140 * key_cleanup() if the keyring is currently 'dead'
1141 * (ie. it has a zero usage count) */
1142 if (!refcount_inc_not_zero(&keyring
->usage
))
1144 keyring
->last_used_at
= ktime_get_real_seconds();
1149 keyring
= ERR_PTR(-ENOKEY
);
1151 read_unlock(&keyring_name_lock
);
1155 static int keyring_detect_cycle_iterator(const void *object
,
1156 void *iterator_data
)
1158 struct keyring_search_context
*ctx
= iterator_data
;
1159 const struct key
*key
= keyring_ptr_to_key(object
);
1161 kenter("{%d}", key
->serial
);
1163 /* We might get a keyring with matching index-key that is nonetheless a
1164 * different keyring. */
1165 if (key
!= ctx
->match_data
.raw_data
)
1168 ctx
->result
= ERR_PTR(-EDEADLK
);
1173 * See if a cycle will will be created by inserting acyclic tree B in acyclic
1174 * tree A at the topmost level (ie: as a direct child of A).
1176 * Since we are adding B to A at the top level, checking for cycles should just
1177 * be a matter of seeing if node A is somewhere in tree B.
1179 static int keyring_detect_cycle(struct key
*A
, struct key
*B
)
1181 struct keyring_search_context ctx
= {
1182 .index_key
= A
->index_key
,
1183 .match_data
.raw_data
= A
,
1184 .match_data
.lookup_type
= KEYRING_SEARCH_LOOKUP_DIRECT
,
1185 .iterator
= keyring_detect_cycle_iterator
,
1186 .flags
= (KEYRING_SEARCH_NO_STATE_CHECK
|
1187 KEYRING_SEARCH_NO_UPDATE_TIME
|
1188 KEYRING_SEARCH_NO_CHECK_PERM
|
1189 KEYRING_SEARCH_DETECT_TOO_DEEP
),
1193 search_nested_keyrings(B
, &ctx
);
1195 return PTR_ERR(ctx
.result
) == -EAGAIN
? 0 : PTR_ERR(ctx
.result
);
1199 * Preallocate memory so that a key can be linked into to a keyring.
1201 int __key_link_begin(struct key
*keyring
,
1202 const struct keyring_index_key
*index_key
,
1203 struct assoc_array_edit
**_edit
)
1204 __acquires(&keyring
->sem
)
1205 __acquires(&keyring_serialise_link_sem
)
1207 struct assoc_array_edit
*edit
;
1211 keyring
->serial
, index_key
->type
->name
, index_key
->description
);
1213 BUG_ON(index_key
->desc_len
== 0);
1215 if (keyring
->type
!= &key_type_keyring
)
1218 down_write(&keyring
->sem
);
1221 if (test_bit(KEY_FLAG_REVOKED
, &keyring
->flags
))
1224 /* serialise link/link calls to prevent parallel calls causing a cycle
1225 * when linking two keyring in opposite orders */
1226 if (index_key
->type
== &key_type_keyring
)
1227 down_write(&keyring_serialise_link_sem
);
1229 /* Create an edit script that will insert/replace the key in the
1232 edit
= assoc_array_insert(&keyring
->keys
,
1233 &keyring_assoc_array_ops
,
1237 ret
= PTR_ERR(edit
);
1241 /* If we're not replacing a link in-place then we're going to need some
1244 if (!edit
->dead_leaf
) {
1245 ret
= key_payload_reserve(keyring
,
1246 keyring
->datalen
+ KEYQUOTA_LINK_BYTES
);
1256 assoc_array_cancel_edit(edit
);
1258 if (index_key
->type
== &key_type_keyring
)
1259 up_write(&keyring_serialise_link_sem
);
1261 up_write(&keyring
->sem
);
1262 kleave(" = %d", ret
);
1267 * Check already instantiated keys aren't going to be a problem.
1269 * The caller must have called __key_link_begin(). Don't need to call this for
1270 * keys that were created since __key_link_begin() was called.
1272 int __key_link_check_live_key(struct key
*keyring
, struct key
*key
)
1274 if (key
->type
== &key_type_keyring
)
1275 /* check that we aren't going to create a cycle by linking one
1276 * keyring to another */
1277 return keyring_detect_cycle(keyring
, key
);
1282 * Link a key into to a keyring.
1284 * Must be called with __key_link_begin() having being called. Discards any
1285 * already extant link to matching key if there is one, so that each keyring
1286 * holds at most one link to any given key of a particular type+description
1289 void __key_link(struct key
*key
, struct assoc_array_edit
**_edit
)
1292 assoc_array_insert_set_object(*_edit
, keyring_key_to_ptr(key
));
1293 assoc_array_apply_edit(*_edit
);
1298 * Finish linking a key into to a keyring.
1300 * Must be called with __key_link_begin() having being called.
1302 void __key_link_end(struct key
*keyring
,
1303 const struct keyring_index_key
*index_key
,
1304 struct assoc_array_edit
*edit
)
1305 __releases(&keyring
->sem
)
1306 __releases(&keyring_serialise_link_sem
)
1308 BUG_ON(index_key
->type
== NULL
);
1309 kenter("%d,%s,", keyring
->serial
, index_key
->type
->name
);
1311 if (index_key
->type
== &key_type_keyring
)
1312 up_write(&keyring_serialise_link_sem
);
1315 if (!edit
->dead_leaf
) {
1316 key_payload_reserve(keyring
,
1317 keyring
->datalen
- KEYQUOTA_LINK_BYTES
);
1319 assoc_array_cancel_edit(edit
);
1321 up_write(&keyring
->sem
);
1325 * Check addition of keys to restricted keyrings.
1327 static int __key_link_check_restriction(struct key
*keyring
, struct key
*key
)
1329 if (!keyring
->restrict_link
|| !keyring
->restrict_link
->check
)
1331 return keyring
->restrict_link
->check(keyring
, key
->type
, &key
->payload
,
1332 keyring
->restrict_link
->key
);
1336 * key_link - Link a key to a keyring
1337 * @keyring: The keyring to make the link in.
1338 * @key: The key to link to.
1340 * Make a link in a keyring to a key, such that the keyring holds a reference
1341 * on that key and the key can potentially be found by searching that keyring.
1343 * This function will write-lock the keyring's semaphore and will consume some
1344 * of the user's key data quota to hold the link.
1346 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1347 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1348 * full, -EDQUOT if there is insufficient key data quota remaining to add
1349 * another link or -ENOMEM if there's insufficient memory.
1351 * It is assumed that the caller has checked that it is permitted for a link to
1352 * be made (the keyring should have Write permission and the key Link
1355 int key_link(struct key
*keyring
, struct key
*key
)
1357 struct assoc_array_edit
*edit
;
1360 kenter("{%d,%d}", keyring
->serial
, refcount_read(&keyring
->usage
));
1365 ret
= __key_link_begin(keyring
, &key
->index_key
, &edit
);
1367 kdebug("begun {%d,%d}", keyring
->serial
, refcount_read(&keyring
->usage
));
1368 ret
= __key_link_check_restriction(keyring
, key
);
1370 ret
= __key_link_check_live_key(keyring
, key
);
1372 __key_link(key
, &edit
);
1373 __key_link_end(keyring
, &key
->index_key
, edit
);
1376 kleave(" = %d {%d,%d}", ret
, keyring
->serial
, refcount_read(&keyring
->usage
));
1379 EXPORT_SYMBOL(key_link
);
1382 * key_unlink - Unlink the first link to a key from a keyring.
1383 * @keyring: The keyring to remove the link from.
1384 * @key: The key the link is to.
1386 * Remove a link from a keyring to a key.
1388 * This function will write-lock the keyring's semaphore.
1390 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1391 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1394 * It is assumed that the caller has checked that it is permitted for a link to
1395 * be removed (the keyring should have Write permission; no permissions are
1396 * required on the key).
1398 int key_unlink(struct key
*keyring
, struct key
*key
)
1400 struct assoc_array_edit
*edit
;
1406 if (keyring
->type
!= &key_type_keyring
)
1409 down_write(&keyring
->sem
);
1411 edit
= assoc_array_delete(&keyring
->keys
, &keyring_assoc_array_ops
,
1414 ret
= PTR_ERR(edit
);
1421 assoc_array_apply_edit(edit
);
1422 key_payload_reserve(keyring
, keyring
->datalen
- KEYQUOTA_LINK_BYTES
);
1426 up_write(&keyring
->sem
);
1429 EXPORT_SYMBOL(key_unlink
);
1432 * keyring_clear - Clear a keyring
1433 * @keyring: The keyring to clear.
1435 * Clear the contents of the specified keyring.
1437 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1439 int keyring_clear(struct key
*keyring
)
1441 struct assoc_array_edit
*edit
;
1444 if (keyring
->type
!= &key_type_keyring
)
1447 down_write(&keyring
->sem
);
1449 edit
= assoc_array_clear(&keyring
->keys
, &keyring_assoc_array_ops
);
1451 ret
= PTR_ERR(edit
);
1454 assoc_array_apply_edit(edit
);
1455 key_payload_reserve(keyring
, 0);
1459 up_write(&keyring
->sem
);
1462 EXPORT_SYMBOL(keyring_clear
);
1465 * Dispose of the links from a revoked keyring.
1467 * This is called with the key sem write-locked.
1469 static void keyring_revoke(struct key
*keyring
)
1471 struct assoc_array_edit
*edit
;
1473 edit
= assoc_array_clear(&keyring
->keys
, &keyring_assoc_array_ops
);
1474 if (!IS_ERR(edit
)) {
1476 assoc_array_apply_edit(edit
);
1477 key_payload_reserve(keyring
, 0);
1481 static bool keyring_gc_select_iterator(void *object
, void *iterator_data
)
1483 struct key
*key
= keyring_ptr_to_key(object
);
1484 time64_t
*limit
= iterator_data
;
1486 if (key_is_dead(key
, *limit
))
1492 static int keyring_gc_check_iterator(const void *object
, void *iterator_data
)
1494 const struct key
*key
= keyring_ptr_to_key(object
);
1495 time64_t
*limit
= iterator_data
;
1498 return key_is_dead(key
, *limit
);
1502 * Garbage collect pointers from a keyring.
1504 * Not called with any locks held. The keyring's key struct will not be
1505 * deallocated under us as only our caller may deallocate it.
1507 void keyring_gc(struct key
*keyring
, time64_t limit
)
1511 kenter("%x{%s}", keyring
->serial
, keyring
->description
?: "");
1513 if (keyring
->flags
& ((1 << KEY_FLAG_INVALIDATED
) |
1514 (1 << KEY_FLAG_REVOKED
)))
1517 /* scan the keyring looking for dead keys */
1519 result
= assoc_array_iterate(&keyring
->keys
,
1520 keyring_gc_check_iterator
, &limit
);
1530 down_write(&keyring
->sem
);
1531 assoc_array_gc(&keyring
->keys
, &keyring_assoc_array_ops
,
1532 keyring_gc_select_iterator
, &limit
);
1533 up_write(&keyring
->sem
);
1538 * Garbage collect restriction pointers from a keyring.
1540 * Keyring restrictions are associated with a key type, and must be cleaned
1541 * up if the key type is unregistered. The restriction is altered to always
1542 * reject additional keys so a keyring cannot be opened up by unregistering
1545 * Not called with any keyring locks held. The keyring's key struct will not
1546 * be deallocated under us as only our caller may deallocate it.
1548 * The caller is required to hold key_types_sem and dead_type->sem. This is
1549 * fulfilled by key_gc_keytype() holding the locks on behalf of
1550 * key_garbage_collector(), which it invokes on a workqueue.
1552 void keyring_restriction_gc(struct key
*keyring
, struct key_type
*dead_type
)
1554 struct key_restriction
*keyres
;
1556 kenter("%x{%s}", keyring
->serial
, keyring
->description
?: "");
1559 * keyring->restrict_link is only assigned at key allocation time
1560 * or with the key type locked, so the only values that could be
1561 * concurrently assigned to keyring->restrict_link are for key
1562 * types other than dead_type. Given this, it's ok to check
1563 * the key type before acquiring keyring->sem.
1565 if (!dead_type
|| !keyring
->restrict_link
||
1566 keyring
->restrict_link
->keytype
!= dead_type
) {
1567 kleave(" [no restriction gc]");
1571 /* Lock the keyring to ensure that a link is not in progress */
1572 down_write(&keyring
->sem
);
1574 keyres
= keyring
->restrict_link
;
1576 keyres
->check
= restrict_link_reject
;
1578 key_put(keyres
->key
);
1580 keyres
->keytype
= NULL
;
1582 up_write(&keyring
->sem
);
1584 kleave(" [restriction gc]");