1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Request a key from userspace
4 * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
7 * See Documentation/security/keys/request-key.rst
10 #include <linux/export.h>
11 #include <linux/sched.h>
12 #include <linux/kmod.h>
13 #include <linux/err.h>
14 #include <linux/keyctl.h>
15 #include <linux/slab.h>
16 #include <net/net_namespace.h>
18 #include <keys/request_key_auth-type.h>
20 #define key_negative_timeout 60 /* default timeout on a negative key's existence */
22 static struct key
*check_cached_key(struct keyring_search_context
*ctx
)
24 #ifdef CONFIG_KEYS_REQUEST_CACHE
25 struct key
*key
= current
->cached_requested_key
;
28 ctx
->match_data
.cmp(key
, &ctx
->match_data
) &&
29 !(key
->flags
& ((1 << KEY_FLAG_INVALIDATED
) |
30 (1 << KEY_FLAG_REVOKED
))))
36 static void cache_requested_key(struct key
*key
)
38 #ifdef CONFIG_KEYS_REQUEST_CACHE
39 struct task_struct
*t
= current
;
41 /* Do not cache key if it is a kernel thread */
42 if (!(t
->flags
& PF_KTHREAD
)) {
43 key_put(t
->cached_requested_key
);
44 t
->cached_requested_key
= key_get(key
);
45 set_tsk_thread_flag(t
, TIF_NOTIFY_RESUME
);
51 * complete_request_key - Complete the construction of a key.
52 * @authkey: The authorisation key.
53 * @error: The success or failute of the construction.
55 * Complete the attempt to construct a key. The key will be negated
56 * if an error is indicated. The authorisation key will be revoked
59 void complete_request_key(struct key
*authkey
, int error
)
61 struct request_key_auth
*rka
= get_request_key_auth(authkey
);
62 struct key
*key
= rka
->target_key
;
64 kenter("%d{%d},%d", authkey
->serial
, key
->serial
, error
);
67 key_negate_and_link(key
, key_negative_timeout
, NULL
, authkey
);
71 EXPORT_SYMBOL(complete_request_key
);
74 * Initialise a usermode helper that is going to have a specific session
77 * This is called in context of freshly forked kthread before kernel_execve(),
78 * so we can simply install the desired session_keyring at this point.
80 static int umh_keys_init(struct subprocess_info
*info
, struct cred
*cred
)
82 struct key
*keyring
= info
->data
;
84 return install_session_keyring_to_cred(cred
, keyring
);
88 * Clean up a usermode helper with session keyring.
90 static void umh_keys_cleanup(struct subprocess_info
*info
)
92 struct key
*keyring
= info
->data
;
97 * Call a usermode helper with a specific session keyring.
99 static int call_usermodehelper_keys(const char *path
, char **argv
, char **envp
,
100 struct key
*session_keyring
, int wait
)
102 struct subprocess_info
*info
;
104 info
= call_usermodehelper_setup(path
, argv
, envp
, GFP_KERNEL
,
105 umh_keys_init
, umh_keys_cleanup
,
110 key_get(session_keyring
);
111 return call_usermodehelper_exec(info
, wait
);
115 * Request userspace finish the construction of a key
116 * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
118 static int call_sbin_request_key(struct key
*authkey
, void *aux
)
120 static char const request_key
[] = "/sbin/request-key";
121 struct request_key_auth
*rka
= get_request_key_auth(authkey
);
122 const struct cred
*cred
= current_cred();
123 key_serial_t prkey
, sskey
;
124 struct key
*key
= rka
->target_key
, *keyring
, *session
, *user_session
;
125 char *argv
[9], *envp
[3], uid_str
[12], gid_str
[12];
126 char key_str
[12], keyring_str
[3][12];
130 kenter("{%d},{%d},%s", key
->serial
, authkey
->serial
, rka
->op
);
132 ret
= look_up_user_keyrings(NULL
, &user_session
);
136 /* allocate a new session keyring */
137 sprintf(desc
, "_req.%u", key
->serial
);
139 cred
= get_current_cred();
140 keyring
= keyring_alloc(desc
, cred
->fsuid
, cred
->fsgid
, cred
,
141 KEY_POS_ALL
| KEY_USR_VIEW
| KEY_USR_READ
,
142 KEY_ALLOC_QUOTA_OVERRUN
, NULL
, NULL
);
144 if (IS_ERR(keyring
)) {
145 ret
= PTR_ERR(keyring
);
149 /* attach the auth key to the session keyring */
150 ret
= key_link(keyring
, authkey
);
154 /* record the UID and GID */
155 sprintf(uid_str
, "%d", from_kuid(&init_user_ns
, cred
->fsuid
));
156 sprintf(gid_str
, "%d", from_kgid(&init_user_ns
, cred
->fsgid
));
158 /* we say which key is under construction */
159 sprintf(key_str
, "%d", key
->serial
);
161 /* we specify the process's default keyrings */
162 sprintf(keyring_str
[0], "%d",
163 cred
->thread_keyring
? cred
->thread_keyring
->serial
: 0);
166 if (cred
->process_keyring
)
167 prkey
= cred
->process_keyring
->serial
;
168 sprintf(keyring_str
[1], "%d", prkey
);
170 session
= cred
->session_keyring
;
172 session
= user_session
;
173 sskey
= session
->serial
;
175 sprintf(keyring_str
[2], "%d", sskey
);
177 /* set up a minimal environment */
179 envp
[i
++] = "HOME=/";
180 envp
[i
++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
183 /* set up the argument list */
185 argv
[i
++] = (char *)request_key
;
186 argv
[i
++] = (char *)rka
->op
;
190 argv
[i
++] = keyring_str
[0];
191 argv
[i
++] = keyring_str
[1];
192 argv
[i
++] = keyring_str
[2];
196 ret
= call_usermodehelper_keys(request_key
, argv
, envp
, keyring
,
198 kdebug("usermode -> 0x%x", ret
);
200 /* ret is the exit/wait code */
201 if (test_bit(KEY_FLAG_USER_CONSTRUCT
, &key
->flags
) ||
202 key_validate(key
) < 0)
205 /* ignore any errors from userspace if the key was
214 key_put(user_session
);
216 complete_request_key(authkey
, ret
);
217 kleave(" = %d", ret
);
222 * Call out to userspace for key construction.
224 * Program failure is ignored in favour of key status.
226 static int construct_key(struct key
*key
, const void *callout_info
,
227 size_t callout_len
, void *aux
,
228 struct key
*dest_keyring
)
230 request_key_actor_t actor
;
234 kenter("%d,%p,%zu,%p", key
->serial
, callout_info
, callout_len
, aux
);
236 /* allocate an authorisation key */
237 authkey
= request_key_auth_new(key
, "create", callout_info
, callout_len
,
240 return PTR_ERR(authkey
);
243 actor
= call_sbin_request_key
;
244 if (key
->type
->request_key
)
245 actor
= key
->type
->request_key
;
247 ret
= actor(authkey
, aux
);
249 /* check that the actor called complete_request_key() prior to
250 * returning an error */
252 !test_bit(KEY_FLAG_INVALIDATED
, &authkey
->flags
));
255 kleave(" = %d", ret
);
260 * Get the appropriate destination keyring for the request.
262 * The keyring selected is returned with an extra reference upon it which the
263 * caller must release.
265 static int construct_get_dest_keyring(struct key
**_dest_keyring
)
267 struct request_key_auth
*rka
;
268 const struct cred
*cred
= current_cred();
269 struct key
*dest_keyring
= *_dest_keyring
, *authkey
;
272 kenter("%p", dest_keyring
);
274 /* find the appropriate keyring */
276 /* the caller supplied one */
277 key_get(dest_keyring
);
279 bool do_perm_check
= true;
281 /* use a default keyring; falling through the cases until we
282 * find one that we actually have */
283 switch (cred
->jit_keyring
) {
284 case KEY_REQKEY_DEFL_DEFAULT
:
285 case KEY_REQKEY_DEFL_REQUESTOR_KEYRING
:
286 if (cred
->request_key_auth
) {
287 authkey
= cred
->request_key_auth
;
288 down_read(&authkey
->sem
);
289 rka
= get_request_key_auth(authkey
);
290 if (!test_bit(KEY_FLAG_REVOKED
,
293 key_get(rka
->dest_keyring
);
294 up_read(&authkey
->sem
);
296 do_perm_check
= false;
302 case KEY_REQKEY_DEFL_THREAD_KEYRING
:
303 dest_keyring
= key_get(cred
->thread_keyring
);
308 case KEY_REQKEY_DEFL_PROCESS_KEYRING
:
309 dest_keyring
= key_get(cred
->process_keyring
);
314 case KEY_REQKEY_DEFL_SESSION_KEYRING
:
315 dest_keyring
= key_get(cred
->session_keyring
);
321 case KEY_REQKEY_DEFL_USER_SESSION_KEYRING
:
322 ret
= look_up_user_keyrings(NULL
, &dest_keyring
);
327 case KEY_REQKEY_DEFL_USER_KEYRING
:
328 ret
= look_up_user_keyrings(&dest_keyring
, NULL
);
333 case KEY_REQKEY_DEFL_GROUP_KEYRING
:
339 * Require Write permission on the keyring. This is essential
340 * because the default keyring may be the session keyring, and
341 * joining a keyring only requires Search permission.
343 * However, this check is skipped for the "requestor keyring" so
344 * that /sbin/request-key can itself use request_key() to add
345 * keys to the original requestor's destination keyring.
347 if (dest_keyring
&& do_perm_check
) {
348 ret
= key_permission(make_key_ref(dest_keyring
, 1),
351 key_put(dest_keyring
);
357 *_dest_keyring
= dest_keyring
;
358 kleave(" [dk %d]", key_serial(dest_keyring
));
363 * Allocate a new key in under-construction state and attempt to link it in to
364 * the requested keyring.
366 * May return a key that's already under construction instead if there was a
367 * race between two thread calling request_key().
369 static int construct_alloc_key(struct keyring_search_context
*ctx
,
370 struct key
*dest_keyring
,
372 struct key_user
*user
,
375 struct assoc_array_edit
*edit
= NULL
;
382 ctx
->index_key
.type
->name
, ctx
->index_key
.description
);
385 mutex_lock(&user
->cons_lock
);
387 perm
= KEY_POS_VIEW
| KEY_POS_SEARCH
| KEY_POS_LINK
| KEY_POS_SETATTR
;
388 perm
|= KEY_USR_VIEW
;
389 if (ctx
->index_key
.type
->read
)
390 perm
|= KEY_POS_READ
;
391 if (ctx
->index_key
.type
== &key_type_keyring
||
392 ctx
->index_key
.type
->update
)
393 perm
|= KEY_POS_WRITE
;
395 key
= key_alloc(ctx
->index_key
.type
, ctx
->index_key
.description
,
396 ctx
->cred
->fsuid
, ctx
->cred
->fsgid
, ctx
->cred
,
401 set_bit(KEY_FLAG_USER_CONSTRUCT
, &key
->flags
);
404 ret
= __key_link_lock(dest_keyring
, &key
->index_key
);
406 goto link_lock_failed
;
410 * Attach the key to the destination keyring under lock, but we do need
411 * to do another check just in case someone beat us to it whilst we
414 * The caller might specify a comparison function which looks for keys
415 * that do not exactly match but are still equivalent from the caller's
416 * perspective. The __key_link_begin() operation must be done only after
417 * an actual key is determined.
419 mutex_lock(&key_construction_mutex
);
422 key_ref
= search_process_keyrings_rcu(ctx
);
424 if (!IS_ERR(key_ref
))
425 goto key_already_present
;
428 ret
= __key_link_begin(dest_keyring
, &key
->index_key
, &edit
);
430 goto link_alloc_failed
;
431 __key_link(dest_keyring
, key
, &edit
);
434 mutex_unlock(&key_construction_mutex
);
436 __key_link_end(dest_keyring
, &key
->index_key
, edit
);
437 mutex_unlock(&user
->cons_lock
);
439 kleave(" = 0 [%d]", key_serial(key
));
442 /* the key is now present - we tell the caller that we found it by
443 * returning -EINPROGRESS */
446 mutex_unlock(&key_construction_mutex
);
447 key
= key_ref_to_ptr(key_ref
);
449 ret
= __key_link_begin(dest_keyring
, &key
->index_key
, &edit
);
451 goto link_alloc_failed_unlocked
;
452 ret
= __key_link_check_live_key(dest_keyring
, key
);
454 __key_link(dest_keyring
, key
, &edit
);
455 __key_link_end(dest_keyring
, &key
->index_key
, edit
);
457 goto link_check_failed
;
459 mutex_unlock(&user
->cons_lock
);
461 kleave(" = -EINPROGRESS [%d]", key_serial(key
));
465 mutex_unlock(&user
->cons_lock
);
467 kleave(" = %d [linkcheck]", ret
);
471 mutex_unlock(&key_construction_mutex
);
472 link_alloc_failed_unlocked
:
473 __key_link_end(dest_keyring
, &key
->index_key
, edit
);
475 mutex_unlock(&user
->cons_lock
);
477 kleave(" = %d [prelink]", ret
);
481 mutex_unlock(&user
->cons_lock
);
482 kleave(" = %ld", PTR_ERR(key
));
487 * Commence key construction.
489 static struct key
*construct_key_and_link(struct keyring_search_context
*ctx
,
490 const char *callout_info
,
493 struct key
*dest_keyring
,
496 struct key_user
*user
;
502 if (ctx
->index_key
.type
== &key_type_keyring
)
503 return ERR_PTR(-EPERM
);
505 ret
= construct_get_dest_keyring(&dest_keyring
);
509 user
= key_user_lookup(current_fsuid());
512 goto error_put_dest_keyring
;
515 ret
= construct_alloc_key(ctx
, dest_keyring
, flags
, user
, &key
);
519 ret
= construct_key(key
, callout_info
, callout_len
, aux
,
522 kdebug("cons failed");
523 goto construction_failed
;
525 } else if (ret
== -EINPROGRESS
) {
528 goto error_put_dest_keyring
;
531 key_put(dest_keyring
);
532 kleave(" = key %d", key_serial(key
));
536 key_negate_and_link(key
, key_negative_timeout
, NULL
, NULL
);
538 error_put_dest_keyring
:
539 key_put(dest_keyring
);
541 kleave(" = %d", ret
);
546 * request_key_and_link - Request a key and cache it in a keyring.
547 * @type: The type of key we want.
548 * @description: The searchable description of the key.
549 * @domain_tag: The domain in which the key operates.
550 * @callout_info: The data to pass to the instantiation upcall (or NULL).
551 * @callout_len: The length of callout_info.
552 * @aux: Auxiliary data for the upcall.
553 * @dest_keyring: Where to cache the key.
554 * @flags: Flags to key_alloc().
556 * A key matching the specified criteria (type, description, domain_tag) is
557 * searched for in the process's keyrings and returned with its usage count
558 * incremented if found. Otherwise, if callout_info is not NULL, a key will be
559 * allocated and some service (probably in userspace) will be asked to
562 * If successfully found or created, the key will be linked to the destination
563 * keyring if one is provided.
565 * Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED
566 * or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was
567 * found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT
568 * if insufficient key quota was available to create a new key; or -ENOMEM if
569 * insufficient memory was available.
571 * If the returned key was created, then it may still be under construction,
572 * and wait_for_key_construction() should be used to wait for that to complete.
574 struct key
*request_key_and_link(struct key_type
*type
,
575 const char *description
,
576 struct key_tag
*domain_tag
,
577 const void *callout_info
,
580 struct key
*dest_keyring
,
583 struct keyring_search_context ctx
= {
584 .index_key
.type
= type
,
585 .index_key
.domain_tag
= domain_tag
,
586 .index_key
.description
= description
,
587 .index_key
.desc_len
= strlen(description
),
588 .cred
= current_cred(),
589 .match_data
.cmp
= key_default_cmp
,
590 .match_data
.raw_data
= description
,
591 .match_data
.lookup_type
= KEYRING_SEARCH_LOOKUP_DIRECT
,
592 .flags
= (KEYRING_SEARCH_DO_STATE_CHECK
|
593 KEYRING_SEARCH_SKIP_EXPIRED
|
594 KEYRING_SEARCH_RECURSE
),
600 kenter("%s,%s,%p,%zu,%p,%p,%lx",
601 ctx
.index_key
.type
->name
, ctx
.index_key
.description
,
602 callout_info
, callout_len
, aux
, dest_keyring
, flags
);
604 if (type
->match_preparse
) {
605 ret
= type
->match_preparse(&ctx
.match_data
);
612 key
= check_cached_key(&ctx
);
616 /* search all the process keyrings for a key */
618 key_ref
= search_process_keyrings_rcu(&ctx
);
621 if (!IS_ERR(key_ref
)) {
623 ret
= key_task_permission(key_ref
, current_cred(),
626 key_ref_put(key_ref
);
632 key
= key_ref_to_ptr(key_ref
);
634 ret
= key_link(dest_keyring
, key
);
642 /* Only cache the key on immediate success */
643 cache_requested_key(key
);
644 } else if (PTR_ERR(key_ref
) != -EAGAIN
) {
645 key
= ERR_CAST(key_ref
);
647 /* the search failed, but the keyrings were searchable, so we
648 * should consult userspace if we can */
649 key
= ERR_PTR(-ENOKEY
);
653 key
= construct_key_and_link(&ctx
, callout_info
, callout_len
,
654 aux
, dest_keyring
, flags
);
658 if (type
->match_free
)
659 type
->match_free(&ctx
.match_data
);
661 kleave(" = %p", key
);
666 * wait_for_key_construction - Wait for construction of a key to complete
667 * @key: The key being waited for.
668 * @intr: Whether to wait interruptibly.
670 * Wait for a key to finish being constructed.
672 * Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY
673 * if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was
674 * revoked or expired.
676 int wait_for_key_construction(struct key
*key
, bool intr
)
680 ret
= wait_on_bit(&key
->flags
, KEY_FLAG_USER_CONSTRUCT
,
681 intr
? TASK_INTERRUPTIBLE
: TASK_UNINTERRUPTIBLE
);
684 ret
= key_read_state(key
);
687 return key_validate(key
);
689 EXPORT_SYMBOL(wait_for_key_construction
);
692 * request_key_tag - Request a key and wait for construction
693 * @type: Type of key.
694 * @description: The searchable description of the key.
695 * @domain_tag: The domain in which the key operates.
696 * @callout_info: The data to pass to the instantiation upcall (or NULL).
698 * As for request_key_and_link() except that it does not add the returned key
699 * to a keyring if found, new keys are always allocated in the user's quota,
700 * the callout_info must be a NUL-terminated string and no auxiliary data can
703 * Furthermore, it then works as wait_for_key_construction() to wait for the
704 * completion of keys undergoing construction with a non-interruptible wait.
706 struct key
*request_key_tag(struct key_type
*type
,
707 const char *description
,
708 struct key_tag
*domain_tag
,
709 const char *callout_info
)
712 size_t callout_len
= 0;
716 callout_len
= strlen(callout_info
);
717 key
= request_key_and_link(type
, description
, domain_tag
,
718 callout_info
, callout_len
,
719 NULL
, NULL
, KEY_ALLOC_IN_QUOTA
);
721 ret
= wait_for_key_construction(key
, false);
729 EXPORT_SYMBOL(request_key_tag
);
732 * request_key_with_auxdata - Request a key with auxiliary data for the upcaller
733 * @type: The type of key we want.
734 * @description: The searchable description of the key.
735 * @domain_tag: The domain in which the key operates.
736 * @callout_info: The data to pass to the instantiation upcall (or NULL).
737 * @callout_len: The length of callout_info.
738 * @aux: Auxiliary data for the upcall.
740 * As for request_key_and_link() except that it does not add the returned key
741 * to a keyring if found and new keys are always allocated in the user's quota.
743 * Furthermore, it then works as wait_for_key_construction() to wait for the
744 * completion of keys undergoing construction with a non-interruptible wait.
746 struct key
*request_key_with_auxdata(struct key_type
*type
,
747 const char *description
,
748 struct key_tag
*domain_tag
,
749 const void *callout_info
,
756 key
= request_key_and_link(type
, description
, domain_tag
,
757 callout_info
, callout_len
,
758 aux
, NULL
, KEY_ALLOC_IN_QUOTA
);
760 ret
= wait_for_key_construction(key
, false);
768 EXPORT_SYMBOL(request_key_with_auxdata
);
771 * request_key_rcu - Request key from RCU-read-locked context
772 * @type: The type of key we want.
773 * @description: The name of the key we want.
774 * @domain_tag: The domain in which the key operates.
776 * Request a key from a context that we may not sleep in (such as RCU-mode
777 * pathwalk). Keys under construction are ignored.
779 * Return a pointer to the found key if successful, -ENOKEY if we couldn't find
780 * a key or some other error if the key found was unsuitable or inaccessible.
782 struct key
*request_key_rcu(struct key_type
*type
,
783 const char *description
,
784 struct key_tag
*domain_tag
)
786 struct keyring_search_context ctx
= {
787 .index_key
.type
= type
,
788 .index_key
.domain_tag
= domain_tag
,
789 .index_key
.description
= description
,
790 .index_key
.desc_len
= strlen(description
),
791 .cred
= current_cred(),
792 .match_data
.cmp
= key_default_cmp
,
793 .match_data
.raw_data
= description
,
794 .match_data
.lookup_type
= KEYRING_SEARCH_LOOKUP_DIRECT
,
795 .flags
= (KEYRING_SEARCH_DO_STATE_CHECK
|
796 KEYRING_SEARCH_SKIP_EXPIRED
),
801 kenter("%s,%s", type
->name
, description
);
803 key
= check_cached_key(&ctx
);
807 /* search all the process keyrings for a key */
808 key_ref
= search_process_keyrings_rcu(&ctx
);
809 if (IS_ERR(key_ref
)) {
810 key
= ERR_CAST(key_ref
);
811 if (PTR_ERR(key_ref
) == -EAGAIN
)
812 key
= ERR_PTR(-ENOKEY
);
814 key
= key_ref_to_ptr(key_ref
);
815 cache_requested_key(key
);
818 kleave(" = %p", key
);
821 EXPORT_SYMBOL(request_key_rcu
);