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
->type_data
.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
->type_data
.link
.next
!= NULL
&&
391 !list_empty(&keyring
->type_data
.link
))
392 list_del(&keyring
->type_data
.link
);
394 write_unlock(&keyring_name_lock
);
397 assoc_array_destroy(&keyring
->keys
, &keyring_assoc_array_ops
);
401 * Describe a keyring for /proc.
403 static void keyring_describe(const struct key
*keyring
, struct seq_file
*m
)
405 if (keyring
->description
)
406 seq_puts(m
, keyring
->description
);
408 seq_puts(m
, "[anon]");
410 if (key_is_instantiated(keyring
)) {
411 if (keyring
->keys
.nr_leaves_on_tree
!= 0)
412 seq_printf(m
, ": %lu", keyring
->keys
.nr_leaves_on_tree
);
414 seq_puts(m
, ": empty");
418 struct keyring_read_iterator_context
{
421 key_serial_t __user
*buffer
;
424 static int keyring_read_iterator(const void *object
, void *data
)
426 struct keyring_read_iterator_context
*ctx
= data
;
427 const struct key
*key
= keyring_ptr_to_key(object
);
430 kenter("{%s,%d},,{%zu/%zu}",
431 key
->type
->name
, key
->serial
, ctx
->count
, ctx
->qty
);
433 if (ctx
->count
>= ctx
->qty
)
436 ret
= put_user(key
->serial
, ctx
->buffer
);
440 ctx
->count
+= sizeof(key
->serial
);
445 * Read a list of key IDs from the keyring's contents in binary form
447 * The keyring's semaphore is read-locked by the caller. This prevents someone
448 * from modifying it under us - which could cause us to read key IDs multiple
451 static long keyring_read(const struct key
*keyring
,
452 char __user
*buffer
, size_t buflen
)
454 struct keyring_read_iterator_context ctx
;
455 unsigned long nr_keys
;
458 kenter("{%d},,%zu", key_serial(keyring
), buflen
);
460 if (buflen
& (sizeof(key_serial_t
) - 1))
463 nr_keys
= keyring
->keys
.nr_leaves_on_tree
;
467 /* Calculate how much data we could return */
468 ctx
.qty
= nr_keys
* sizeof(key_serial_t
);
470 if (!buffer
|| !buflen
)
473 if (buflen
> ctx
.qty
)
476 /* Copy the IDs of the subscribed keys into the buffer */
477 ctx
.buffer
= (key_serial_t __user
*)buffer
;
479 ret
= assoc_array_iterate(&keyring
->keys
, keyring_read_iterator
, &ctx
);
481 kleave(" = %d [iterate]", ret
);
485 kleave(" = %zu [ok]", ctx
.count
);
490 * Allocate a keyring and link into the destination keyring.
492 struct key
*keyring_alloc(const char *description
, kuid_t uid
, kgid_t gid
,
493 const struct cred
*cred
, key_perm_t perm
,
494 unsigned long flags
, struct key
*dest
)
499 keyring
= key_alloc(&key_type_keyring
, description
,
500 uid
, gid
, cred
, perm
, flags
);
501 if (!IS_ERR(keyring
)) {
502 ret
= key_instantiate_and_link(keyring
, NULL
, 0, dest
, NULL
);
505 keyring
= ERR_PTR(ret
);
511 EXPORT_SYMBOL(keyring_alloc
);
514 * By default, we keys found by getting an exact match on their descriptions.
516 bool key_default_cmp(const struct key
*key
,
517 const struct key_match_data
*match_data
)
519 return strcmp(key
->description
, match_data
->raw_data
) == 0;
523 * Iteration function to consider each key found.
525 static int keyring_search_iterator(const void *object
, void *iterator_data
)
527 struct keyring_search_context
*ctx
= iterator_data
;
528 const struct key
*key
= keyring_ptr_to_key(object
);
529 unsigned long kflags
= key
->flags
;
531 kenter("{%d}", key
->serial
);
533 /* ignore keys not of this type */
534 if (key
->type
!= ctx
->index_key
.type
) {
535 kleave(" = 0 [!type]");
539 /* skip invalidated, revoked and expired keys */
540 if (ctx
->flags
& KEYRING_SEARCH_DO_STATE_CHECK
) {
541 if (kflags
& ((1 << KEY_FLAG_INVALIDATED
) |
542 (1 << KEY_FLAG_REVOKED
))) {
543 ctx
->result
= ERR_PTR(-EKEYREVOKED
);
544 kleave(" = %d [invrev]", ctx
->skipped_ret
);
548 if (key
->expiry
&& ctx
->now
.tv_sec
>= key
->expiry
) {
549 ctx
->result
= ERR_PTR(-EKEYEXPIRED
);
550 kleave(" = %d [expire]", ctx
->skipped_ret
);
555 /* keys that don't match */
556 if (!ctx
->match_data
.cmp(key
, &ctx
->match_data
)) {
557 kleave(" = 0 [!match]");
561 /* key must have search permissions */
562 if (!(ctx
->flags
& KEYRING_SEARCH_NO_CHECK_PERM
) &&
563 key_task_permission(make_key_ref(key
, ctx
->possessed
),
564 ctx
->cred
, KEY_NEED_SEARCH
) < 0) {
565 ctx
->result
= ERR_PTR(-EACCES
);
566 kleave(" = %d [!perm]", ctx
->skipped_ret
);
570 if (ctx
->flags
& KEYRING_SEARCH_DO_STATE_CHECK
) {
571 /* we set a different error code if we pass a negative key */
572 if (kflags
& (1 << KEY_FLAG_NEGATIVE
)) {
574 ctx
->result
= ERR_PTR(key
->type_data
.reject_error
);
575 kleave(" = %d [neg]", ctx
->skipped_ret
);
581 ctx
->result
= make_key_ref(key
, ctx
->possessed
);
582 kleave(" = 1 [found]");
586 return ctx
->skipped_ret
;
590 * Search inside a keyring for a key. We can search by walking to it
591 * directly based on its index-key or we can iterate over the entire
592 * tree looking for it, based on the match function.
594 static int search_keyring(struct key
*keyring
, struct keyring_search_context
*ctx
)
596 if (ctx
->match_data
.lookup_type
== KEYRING_SEARCH_LOOKUP_DIRECT
) {
599 object
= assoc_array_find(&keyring
->keys
,
600 &keyring_assoc_array_ops
,
602 return object
? ctx
->iterator(object
, ctx
) : 0;
604 return assoc_array_iterate(&keyring
->keys
, ctx
->iterator
, ctx
);
608 * Search a tree of keyrings that point to other keyrings up to the maximum
611 static bool search_nested_keyrings(struct key
*keyring
,
612 struct keyring_search_context
*ctx
)
616 struct assoc_array_node
*node
;
618 } stack
[KEYRING_SEARCH_MAX_DEPTH
];
620 struct assoc_array_shortcut
*shortcut
;
621 struct assoc_array_node
*node
;
622 struct assoc_array_ptr
*ptr
;
626 kenter("{%d},{%s,%s}",
628 ctx
->index_key
.type
->name
,
629 ctx
->index_key
.description
);
631 if (ctx
->index_key
.description
)
632 ctx
->index_key
.desc_len
= strlen(ctx
->index_key
.description
);
634 /* Check to see if this top-level keyring is what we are looking for
635 * and whether it is valid or not.
637 if (ctx
->match_data
.lookup_type
== KEYRING_SEARCH_LOOKUP_ITERATE
||
638 keyring_compare_object(keyring
, &ctx
->index_key
)) {
639 ctx
->skipped_ret
= 2;
640 ctx
->flags
|= KEYRING_SEARCH_DO_STATE_CHECK
;
641 switch (ctx
->iterator(keyring_key_to_ptr(keyring
), ctx
)) {
651 ctx
->skipped_ret
= 0;
652 if (ctx
->flags
& KEYRING_SEARCH_NO_STATE_CHECK
)
653 ctx
->flags
&= ~KEYRING_SEARCH_DO_STATE_CHECK
;
655 /* Start processing a new keyring */
657 kdebug("descend to %d", keyring
->serial
);
658 if (keyring
->flags
& ((1 << KEY_FLAG_INVALIDATED
) |
659 (1 << KEY_FLAG_REVOKED
)))
660 goto not_this_keyring
;
662 /* Search through the keys in this keyring before its searching its
665 if (search_keyring(keyring
, ctx
))
668 /* Then manually iterate through the keyrings nested in this one.
670 * Start from the root node of the index tree. Because of the way the
671 * hash function has been set up, keyrings cluster on the leftmost
672 * branch of the root node (root slot 0) or in the root node itself.
673 * Non-keyrings avoid the leftmost branch of the root entirely (root
676 ptr
= ACCESS_ONCE(keyring
->keys
.root
);
678 goto not_this_keyring
;
680 if (assoc_array_ptr_is_shortcut(ptr
)) {
681 /* If the root is a shortcut, either the keyring only contains
682 * keyring pointers (everything clusters behind root slot 0) or
683 * doesn't contain any keyring pointers.
685 shortcut
= assoc_array_ptr_to_shortcut(ptr
);
686 smp_read_barrier_depends();
687 if ((shortcut
->index_key
[0] & ASSOC_ARRAY_FAN_MASK
) != 0)
688 goto not_this_keyring
;
690 ptr
= ACCESS_ONCE(shortcut
->next_node
);
691 node
= assoc_array_ptr_to_node(ptr
);
695 node
= assoc_array_ptr_to_node(ptr
);
696 smp_read_barrier_depends();
698 ptr
= node
->slots
[0];
699 if (!assoc_array_ptr_is_meta(ptr
))
703 /* Descend to a more distal node in this keyring's content tree and go
707 if (assoc_array_ptr_is_shortcut(ptr
)) {
708 shortcut
= assoc_array_ptr_to_shortcut(ptr
);
709 smp_read_barrier_depends();
710 ptr
= ACCESS_ONCE(shortcut
->next_node
);
711 BUG_ON(!assoc_array_ptr_is_node(ptr
));
713 node
= assoc_array_ptr_to_node(ptr
);
716 kdebug("begin_node");
717 smp_read_barrier_depends();
720 /* Go through the slots in a node */
721 for (; slot
< ASSOC_ARRAY_FAN_OUT
; slot
++) {
722 ptr
= ACCESS_ONCE(node
->slots
[slot
]);
724 if (assoc_array_ptr_is_meta(ptr
) && node
->back_pointer
)
725 goto descend_to_node
;
727 if (!keyring_ptr_is_keyring(ptr
))
730 key
= keyring_ptr_to_key(ptr
);
732 if (sp
>= KEYRING_SEARCH_MAX_DEPTH
) {
733 if (ctx
->flags
& KEYRING_SEARCH_DETECT_TOO_DEEP
) {
734 ctx
->result
= ERR_PTR(-ELOOP
);
737 goto not_this_keyring
;
740 /* Search a nested keyring */
741 if (!(ctx
->flags
& KEYRING_SEARCH_NO_CHECK_PERM
) &&
742 key_task_permission(make_key_ref(key
, ctx
->possessed
),
743 ctx
->cred
, KEY_NEED_SEARCH
) < 0)
746 /* stack the current position */
747 stack
[sp
].keyring
= keyring
;
748 stack
[sp
].node
= node
;
749 stack
[sp
].slot
= slot
;
752 /* begin again with the new keyring */
754 goto descend_to_keyring
;
757 /* We've dealt with all the slots in the current node, so now we need
758 * to ascend to the parent and continue processing there.
760 ptr
= ACCESS_ONCE(node
->back_pointer
);
761 slot
= node
->parent_slot
;
763 if (ptr
&& assoc_array_ptr_is_shortcut(ptr
)) {
764 shortcut
= assoc_array_ptr_to_shortcut(ptr
);
765 smp_read_barrier_depends();
766 ptr
= ACCESS_ONCE(shortcut
->back_pointer
);
767 slot
= shortcut
->parent_slot
;
770 goto not_this_keyring
;
771 node
= assoc_array_ptr_to_node(ptr
);
772 smp_read_barrier_depends();
775 /* If we've ascended to the root (zero backpointer), we must have just
776 * finished processing the leftmost branch rather than the root slots -
777 * so there can't be any more keyrings for us to find.
779 if (node
->back_pointer
) {
780 kdebug("ascend %d", slot
);
784 /* The keyring we're looking at was disqualified or didn't contain a
788 kdebug("not_this_keyring %d", sp
);
794 /* Resume the processing of a keyring higher up in the tree */
796 keyring
= stack
[sp
].keyring
;
797 node
= stack
[sp
].node
;
798 slot
= stack
[sp
].slot
+ 1;
799 kdebug("ascend to %d [%d]", keyring
->serial
, slot
);
802 /* We found a viable match */
804 key
= key_ref_to_ptr(ctx
->result
);
806 if (!(ctx
->flags
& KEYRING_SEARCH_NO_UPDATE_TIME
)) {
807 key
->last_used_at
= ctx
->now
.tv_sec
;
808 keyring
->last_used_at
= ctx
->now
.tv_sec
;
810 stack
[--sp
].keyring
->last_used_at
= ctx
->now
.tv_sec
;
817 * keyring_search_aux - Search a keyring tree for a key matching some criteria
818 * @keyring_ref: A pointer to the keyring with possession indicator.
819 * @ctx: The keyring search context.
821 * Search the supplied keyring tree for a key that matches the criteria given.
822 * The root keyring and any linked keyrings must grant Search permission to the
823 * caller to be searchable and keys can only be found if they too grant Search
824 * to the caller. The possession flag on the root keyring pointer controls use
825 * of the possessor bits in permissions checking of the entire tree. In
826 * addition, the LSM gets to forbid keyring searches and key matches.
828 * The search is performed as a breadth-then-depth search up to the prescribed
829 * limit (KEYRING_SEARCH_MAX_DEPTH).
831 * Keys are matched to the type provided and are then filtered by the match
832 * function, which is given the description to use in any way it sees fit. The
833 * match function may use any attributes of a key that it wishes to to
834 * determine the match. Normally the match function from the key type would be
837 * RCU can be used to prevent the keyring key lists from disappearing without
838 * the need to take lots of locks.
840 * Returns a pointer to the found key and increments the key usage count if
841 * successful; -EAGAIN if no matching keys were found, or if expired or revoked
842 * keys were found; -ENOKEY if only negative keys were found; -ENOTDIR if the
843 * specified keyring wasn't a keyring.
845 * In the case of a successful return, the possession attribute from
846 * @keyring_ref is propagated to the returned key reference.
848 key_ref_t
keyring_search_aux(key_ref_t keyring_ref
,
849 struct keyring_search_context
*ctx
)
854 ctx
->iterator
= keyring_search_iterator
;
855 ctx
->possessed
= is_key_possessed(keyring_ref
);
856 ctx
->result
= ERR_PTR(-EAGAIN
);
858 keyring
= key_ref_to_ptr(keyring_ref
);
861 if (keyring
->type
!= &key_type_keyring
)
862 return ERR_PTR(-ENOTDIR
);
864 if (!(ctx
->flags
& KEYRING_SEARCH_NO_CHECK_PERM
)) {
865 err
= key_task_permission(keyring_ref
, ctx
->cred
, KEY_NEED_SEARCH
);
871 ctx
->now
= current_kernel_time();
872 if (search_nested_keyrings(keyring
, ctx
))
873 __key_get(key_ref_to_ptr(ctx
->result
));
879 * keyring_search - Search the supplied keyring tree for a matching key
880 * @keyring: The root of the keyring tree to be searched.
881 * @type: The type of keyring we want to find.
882 * @description: The name of the keyring we want to find.
884 * As keyring_search_aux() above, but using the current task's credentials and
885 * type's default matching function and preferred search method.
887 key_ref_t
keyring_search(key_ref_t keyring
,
888 struct key_type
*type
,
889 const char *description
)
891 struct keyring_search_context ctx
= {
892 .index_key
.type
= type
,
893 .index_key
.description
= description
,
894 .cred
= current_cred(),
895 .match_data
.cmp
= key_default_cmp
,
896 .match_data
.raw_data
= description
,
897 .match_data
.lookup_type
= KEYRING_SEARCH_LOOKUP_DIRECT
,
898 .flags
= KEYRING_SEARCH_DO_STATE_CHECK
,
903 if (type
->match_preparse
) {
904 ret
= type
->match_preparse(&ctx
.match_data
);
909 key
= keyring_search_aux(keyring
, &ctx
);
911 if (type
->match_free
)
912 type
->match_free(&ctx
.match_data
);
915 EXPORT_SYMBOL(keyring_search
);
918 * Search the given keyring for a key that might be updated.
920 * The caller must guarantee that the keyring is a keyring and that the
921 * permission is granted to modify the keyring as no check is made here. The
922 * caller must also hold a lock on the keyring semaphore.
924 * Returns a pointer to the found key with usage count incremented if
925 * successful and returns NULL if not found. Revoked and invalidated keys are
928 * If successful, the possession indicator is propagated from the keyring ref
929 * to the returned key reference.
931 key_ref_t
find_key_to_update(key_ref_t keyring_ref
,
932 const struct keyring_index_key
*index_key
)
934 struct key
*keyring
, *key
;
937 keyring
= key_ref_to_ptr(keyring_ref
);
939 kenter("{%d},{%s,%s}",
940 keyring
->serial
, index_key
->type
->name
, index_key
->description
);
942 object
= assoc_array_find(&keyring
->keys
, &keyring_assoc_array_ops
,
952 key
= keyring_ptr_to_key(object
);
953 if (key
->flags
& ((1 << KEY_FLAG_INVALIDATED
) |
954 (1 << KEY_FLAG_REVOKED
))) {
955 kleave(" = NULL [x]");
959 kleave(" = {%d}", key
->serial
);
960 return make_key_ref(key
, is_key_possessed(keyring_ref
));
964 * Find a keyring with the specified name.
966 * All named keyrings in the current user namespace are searched, provided they
967 * grant Search permission directly to the caller (unless this check is
968 * skipped). Keyrings whose usage points have reached zero or who have been
969 * revoked are skipped.
971 * Returns a pointer to the keyring with the keyring's refcount having being
972 * incremented on success. -ENOKEY is returned if a key could not be found.
974 struct key
*find_keyring_by_name(const char *name
, bool skip_perm_check
)
980 return ERR_PTR(-EINVAL
);
982 bucket
= keyring_hash(name
);
984 read_lock(&keyring_name_lock
);
986 if (keyring_name_hash
[bucket
].next
) {
987 /* search this hash bucket for a keyring with a matching name
988 * that's readable and that hasn't been revoked */
989 list_for_each_entry(keyring
,
990 &keyring_name_hash
[bucket
],
993 if (!kuid_has_mapping(current_user_ns(), keyring
->user
->uid
))
996 if (test_bit(KEY_FLAG_REVOKED
, &keyring
->flags
))
999 if (strcmp(keyring
->description
, name
) != 0)
1002 if (!skip_perm_check
&&
1003 key_permission(make_key_ref(keyring
, 0),
1004 KEY_NEED_SEARCH
) < 0)
1007 /* we've got a match but we might end up racing with
1008 * key_cleanup() if the keyring is currently 'dead'
1009 * (ie. it has a zero usage count) */
1010 if (!atomic_inc_not_zero(&keyring
->usage
))
1012 keyring
->last_used_at
= current_kernel_time().tv_sec
;
1017 keyring
= ERR_PTR(-ENOKEY
);
1019 read_unlock(&keyring_name_lock
);
1023 static int keyring_detect_cycle_iterator(const void *object
,
1024 void *iterator_data
)
1026 struct keyring_search_context
*ctx
= iterator_data
;
1027 const struct key
*key
= keyring_ptr_to_key(object
);
1029 kenter("{%d}", key
->serial
);
1031 /* We might get a keyring with matching index-key that is nonetheless a
1032 * different keyring. */
1033 if (key
!= ctx
->match_data
.raw_data
)
1036 ctx
->result
= ERR_PTR(-EDEADLK
);
1041 * See if a cycle will will be created by inserting acyclic tree B in acyclic
1042 * tree A at the topmost level (ie: as a direct child of A).
1044 * Since we are adding B to A at the top level, checking for cycles should just
1045 * be a matter of seeing if node A is somewhere in tree B.
1047 static int keyring_detect_cycle(struct key
*A
, struct key
*B
)
1049 struct keyring_search_context ctx
= {
1050 .index_key
= A
->index_key
,
1051 .match_data
.raw_data
= A
,
1052 .match_data
.lookup_type
= KEYRING_SEARCH_LOOKUP_DIRECT
,
1053 .iterator
= keyring_detect_cycle_iterator
,
1054 .flags
= (KEYRING_SEARCH_NO_STATE_CHECK
|
1055 KEYRING_SEARCH_NO_UPDATE_TIME
|
1056 KEYRING_SEARCH_NO_CHECK_PERM
|
1057 KEYRING_SEARCH_DETECT_TOO_DEEP
),
1061 search_nested_keyrings(B
, &ctx
);
1063 return PTR_ERR(ctx
.result
) == -EAGAIN
? 0 : PTR_ERR(ctx
.result
);
1067 * Preallocate memory so that a key can be linked into to a keyring.
1069 int __key_link_begin(struct key
*keyring
,
1070 const struct keyring_index_key
*index_key
,
1071 struct assoc_array_edit
**_edit
)
1072 __acquires(&keyring
->sem
)
1073 __acquires(&keyring_serialise_link_sem
)
1075 struct assoc_array_edit
*edit
;
1079 keyring
->serial
, index_key
->type
->name
, index_key
->description
);
1081 BUG_ON(index_key
->desc_len
== 0);
1083 if (keyring
->type
!= &key_type_keyring
)
1086 down_write(&keyring
->sem
);
1089 if (test_bit(KEY_FLAG_REVOKED
, &keyring
->flags
))
1092 /* serialise link/link calls to prevent parallel calls causing a cycle
1093 * when linking two keyring in opposite orders */
1094 if (index_key
->type
== &key_type_keyring
)
1095 down_write(&keyring_serialise_link_sem
);
1097 /* Create an edit script that will insert/replace the key in the
1100 edit
= assoc_array_insert(&keyring
->keys
,
1101 &keyring_assoc_array_ops
,
1105 ret
= PTR_ERR(edit
);
1109 /* If we're not replacing a link in-place then we're going to need some
1112 if (!edit
->dead_leaf
) {
1113 ret
= key_payload_reserve(keyring
,
1114 keyring
->datalen
+ KEYQUOTA_LINK_BYTES
);
1124 assoc_array_cancel_edit(edit
);
1126 if (index_key
->type
== &key_type_keyring
)
1127 up_write(&keyring_serialise_link_sem
);
1129 up_write(&keyring
->sem
);
1130 kleave(" = %d", ret
);
1135 * Check already instantiated keys aren't going to be a problem.
1137 * The caller must have called __key_link_begin(). Don't need to call this for
1138 * keys that were created since __key_link_begin() was called.
1140 int __key_link_check_live_key(struct key
*keyring
, struct key
*key
)
1142 if (key
->type
== &key_type_keyring
)
1143 /* check that we aren't going to create a cycle by linking one
1144 * keyring to another */
1145 return keyring_detect_cycle(keyring
, key
);
1150 * Link a key into to a keyring.
1152 * Must be called with __key_link_begin() having being called. Discards any
1153 * already extant link to matching key if there is one, so that each keyring
1154 * holds at most one link to any given key of a particular type+description
1157 void __key_link(struct key
*key
, struct assoc_array_edit
**_edit
)
1160 assoc_array_insert_set_object(*_edit
, keyring_key_to_ptr(key
));
1161 assoc_array_apply_edit(*_edit
);
1166 * Finish linking a key into to a keyring.
1168 * Must be called with __key_link_begin() having being called.
1170 void __key_link_end(struct key
*keyring
,
1171 const struct keyring_index_key
*index_key
,
1172 struct assoc_array_edit
*edit
)
1173 __releases(&keyring
->sem
)
1174 __releases(&keyring_serialise_link_sem
)
1176 BUG_ON(index_key
->type
== NULL
);
1177 kenter("%d,%s,", keyring
->serial
, index_key
->type
->name
);
1179 if (index_key
->type
== &key_type_keyring
)
1180 up_write(&keyring_serialise_link_sem
);
1182 if (edit
&& !edit
->dead_leaf
) {
1183 key_payload_reserve(keyring
,
1184 keyring
->datalen
- KEYQUOTA_LINK_BYTES
);
1185 assoc_array_cancel_edit(edit
);
1187 up_write(&keyring
->sem
);
1191 * key_link - Link a key to a keyring
1192 * @keyring: The keyring to make the link in.
1193 * @key: The key to link to.
1195 * Make a link in a keyring to a key, such that the keyring holds a reference
1196 * on that key and the key can potentially be found by searching that keyring.
1198 * This function will write-lock the keyring's semaphore and will consume some
1199 * of the user's key data quota to hold the link.
1201 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring,
1202 * -EKEYREVOKED if the keyring has been revoked, -ENFILE if the keyring is
1203 * full, -EDQUOT if there is insufficient key data quota remaining to add
1204 * another link or -ENOMEM if there's insufficient memory.
1206 * It is assumed that the caller has checked that it is permitted for a link to
1207 * be made (the keyring should have Write permission and the key Link
1210 int key_link(struct key
*keyring
, struct key
*key
)
1212 struct assoc_array_edit
*edit
;
1215 kenter("{%d,%d}", keyring
->serial
, atomic_read(&keyring
->usage
));
1220 if (test_bit(KEY_FLAG_TRUSTED_ONLY
, &keyring
->flags
) &&
1221 !test_bit(KEY_FLAG_TRUSTED
, &key
->flags
))
1224 ret
= __key_link_begin(keyring
, &key
->index_key
, &edit
);
1226 kdebug("begun {%d,%d}", keyring
->serial
, atomic_read(&keyring
->usage
));
1227 ret
= __key_link_check_live_key(keyring
, key
);
1229 __key_link(key
, &edit
);
1230 __key_link_end(keyring
, &key
->index_key
, edit
);
1233 kleave(" = %d {%d,%d}", ret
, keyring
->serial
, atomic_read(&keyring
->usage
));
1236 EXPORT_SYMBOL(key_link
);
1239 * key_unlink - Unlink the first link to a key from a keyring.
1240 * @keyring: The keyring to remove the link from.
1241 * @key: The key the link is to.
1243 * Remove a link from a keyring to a key.
1245 * This function will write-lock the keyring's semaphore.
1247 * Returns 0 if successful, -ENOTDIR if the keyring isn't a keyring, -ENOENT if
1248 * the key isn't linked to by the keyring or -ENOMEM if there's insufficient
1251 * It is assumed that the caller has checked that it is permitted for a link to
1252 * be removed (the keyring should have Write permission; no permissions are
1253 * required on the key).
1255 int key_unlink(struct key
*keyring
, struct key
*key
)
1257 struct assoc_array_edit
*edit
;
1263 if (keyring
->type
!= &key_type_keyring
)
1266 down_write(&keyring
->sem
);
1268 edit
= assoc_array_delete(&keyring
->keys
, &keyring_assoc_array_ops
,
1271 ret
= PTR_ERR(edit
);
1278 assoc_array_apply_edit(edit
);
1279 key_payload_reserve(keyring
, keyring
->datalen
- KEYQUOTA_LINK_BYTES
);
1283 up_write(&keyring
->sem
);
1286 EXPORT_SYMBOL(key_unlink
);
1289 * keyring_clear - Clear a keyring
1290 * @keyring: The keyring to clear.
1292 * Clear the contents of the specified keyring.
1294 * Returns 0 if successful or -ENOTDIR if the keyring isn't a keyring.
1296 int keyring_clear(struct key
*keyring
)
1298 struct assoc_array_edit
*edit
;
1301 if (keyring
->type
!= &key_type_keyring
)
1304 down_write(&keyring
->sem
);
1306 edit
= assoc_array_clear(&keyring
->keys
, &keyring_assoc_array_ops
);
1308 ret
= PTR_ERR(edit
);
1311 assoc_array_apply_edit(edit
);
1312 key_payload_reserve(keyring
, 0);
1316 up_write(&keyring
->sem
);
1319 EXPORT_SYMBOL(keyring_clear
);
1322 * Dispose of the links from a revoked keyring.
1324 * This is called with the key sem write-locked.
1326 static void keyring_revoke(struct key
*keyring
)
1328 struct assoc_array_edit
*edit
;
1330 edit
= assoc_array_clear(&keyring
->keys
, &keyring_assoc_array_ops
);
1331 if (!IS_ERR(edit
)) {
1333 assoc_array_apply_edit(edit
);
1334 key_payload_reserve(keyring
, 0);
1338 static bool keyring_gc_select_iterator(void *object
, void *iterator_data
)
1340 struct key
*key
= keyring_ptr_to_key(object
);
1341 time_t *limit
= iterator_data
;
1343 if (key_is_dead(key
, *limit
))
1349 static int keyring_gc_check_iterator(const void *object
, void *iterator_data
)
1351 const struct key
*key
= keyring_ptr_to_key(object
);
1352 time_t *limit
= iterator_data
;
1355 return key_is_dead(key
, *limit
);
1359 * Garbage collect pointers from a keyring.
1361 * Not called with any locks held. The keyring's key struct will not be
1362 * deallocated under us as only our caller may deallocate it.
1364 void keyring_gc(struct key
*keyring
, time_t limit
)
1368 kenter("%x{%s}", keyring
->serial
, keyring
->description
?: "");
1370 if (keyring
->flags
& ((1 << KEY_FLAG_INVALIDATED
) |
1371 (1 << KEY_FLAG_REVOKED
)))
1374 /* scan the keyring looking for dead keys */
1376 result
= assoc_array_iterate(&keyring
->keys
,
1377 keyring_gc_check_iterator
, &limit
);
1387 down_write(&keyring
->sem
);
1388 assoc_array_gc(&keyring
->keys
, &keyring_assoc_array_ops
,
1389 keyring_gc_select_iterator
, &limit
);
1390 up_write(&keyring
->sem
);