1 /* Request a key from userspace
3 * Copyright (C) 2004-2007 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.
11 * See Documentation/security/keys-request-key.txt
14 #include <linux/module.h>
15 #include <linux/sched.h>
16 #include <linux/kmod.h>
17 #include <linux/err.h>
18 #include <linux/keyctl.h>
19 #include <linux/slab.h>
22 #define key_negative_timeout 60 /* default timeout on a negative key's existence */
25 * wait_on_bit() sleep function for uninterruptible waiting
27 static int key_wait_bit(void *flags
)
34 * wait_on_bit() sleep function for interruptible waiting
36 static int key_wait_bit_intr(void *flags
)
39 return signal_pending(current
) ? -ERESTARTSYS
: 0;
43 * complete_request_key - Complete the construction of a key.
44 * @cons: The key construction record.
45 * @error: The success or failute of the construction.
47 * Complete the attempt to construct a key. The key will be negated
48 * if an error is indicated. The authorisation key will be revoked
51 void complete_request_key(struct key_construction
*cons
, int error
)
53 kenter("{%d,%d},%d", cons
->key
->serial
, cons
->authkey
->serial
, error
);
56 key_negate_and_link(cons
->key
, key_negative_timeout
, NULL
,
59 key_revoke(cons
->authkey
);
62 key_put(cons
->authkey
);
65 EXPORT_SYMBOL(complete_request_key
);
68 * Initialise a usermode helper that is going to have a specific session
71 * This is called in context of freshly forked kthread before kernel_execve(),
72 * so we can simply install the desired session_keyring at this point.
74 static int umh_keys_init(struct subprocess_info
*info
, struct cred
*cred
)
76 struct key
*keyring
= info
->data
;
78 return install_session_keyring_to_cred(cred
, keyring
);
82 * Clean up a usermode helper with session keyring.
84 static void umh_keys_cleanup(struct subprocess_info
*info
)
86 struct key
*keyring
= info
->data
;
91 * Call a usermode helper with a specific session keyring.
93 static int call_usermodehelper_keys(char *path
, char **argv
, char **envp
,
94 struct key
*session_keyring
, int wait
)
96 return call_usermodehelper_fns(path
, argv
, envp
, wait
,
97 umh_keys_init
, umh_keys_cleanup
,
98 key_get(session_keyring
));
102 * Request userspace finish the construction of a key
103 * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
105 static int call_sbin_request_key(struct key_construction
*cons
,
109 const struct cred
*cred
= current_cred();
110 key_serial_t prkey
, sskey
;
111 struct key
*key
= cons
->key
, *authkey
= cons
->authkey
, *keyring
,
113 char *argv
[9], *envp
[3], uid_str
[12], gid_str
[12];
114 char key_str
[12], keyring_str
[3][12];
118 kenter("{%d},{%d},%s", key
->serial
, authkey
->serial
, op
);
120 ret
= install_user_keyrings();
124 /* allocate a new session keyring */
125 sprintf(desc
, "_req.%u", key
->serial
);
127 cred
= get_current_cred();
128 keyring
= keyring_alloc(desc
, cred
->fsuid
, cred
->fsgid
, cred
,
129 KEY_POS_ALL
| KEY_USR_VIEW
| KEY_USR_READ
,
130 KEY_ALLOC_QUOTA_OVERRUN
, NULL
);
132 if (IS_ERR(keyring
)) {
133 ret
= PTR_ERR(keyring
);
137 /* attach the auth key to the session keyring */
138 ret
= key_link(keyring
, authkey
);
142 /* record the UID and GID */
143 sprintf(uid_str
, "%d", from_kuid(&init_user_ns
, cred
->fsuid
));
144 sprintf(gid_str
, "%d", from_kgid(&init_user_ns
, cred
->fsgid
));
146 /* we say which key is under construction */
147 sprintf(key_str
, "%d", key
->serial
);
149 /* we specify the process's default keyrings */
150 sprintf(keyring_str
[0], "%d",
151 cred
->thread_keyring
? cred
->thread_keyring
->serial
: 0);
154 if (cred
->process_keyring
)
155 prkey
= cred
->process_keyring
->serial
;
156 sprintf(keyring_str
[1], "%d", prkey
);
159 session
= rcu_dereference(cred
->session_keyring
);
161 session
= cred
->user
->session_keyring
;
162 sskey
= session
->serial
;
165 sprintf(keyring_str
[2], "%d", sskey
);
167 /* set up a minimal environment */
169 envp
[i
++] = "HOME=/";
170 envp
[i
++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
173 /* set up the argument list */
175 argv
[i
++] = "/sbin/request-key";
176 argv
[i
++] = (char *) op
;
180 argv
[i
++] = keyring_str
[0];
181 argv
[i
++] = keyring_str
[1];
182 argv
[i
++] = keyring_str
[2];
186 ret
= call_usermodehelper_keys(argv
[0], argv
, envp
, keyring
,
188 kdebug("usermode -> 0x%x", ret
);
190 /* ret is the exit/wait code */
191 if (test_bit(KEY_FLAG_USER_CONSTRUCT
, &key
->flags
) ||
192 key_validate(key
) < 0)
195 /* ignore any errors from userspace if the key was
204 complete_request_key(cons
, ret
);
205 kleave(" = %d", ret
);
210 * Call out to userspace for key construction.
212 * Program failure is ignored in favour of key status.
214 static int construct_key(struct key
*key
, const void *callout_info
,
215 size_t callout_len
, void *aux
,
216 struct key
*dest_keyring
)
218 struct key_construction
*cons
;
219 request_key_actor_t actor
;
223 kenter("%d,%p,%zu,%p", key
->serial
, callout_info
, callout_len
, aux
);
225 cons
= kmalloc(sizeof(*cons
), GFP_KERNEL
);
229 /* allocate an authorisation key */
230 authkey
= request_key_auth_new(key
, callout_info
, callout_len
,
232 if (IS_ERR(authkey
)) {
234 ret
= PTR_ERR(authkey
);
237 cons
->authkey
= key_get(authkey
);
238 cons
->key
= key_get(key
);
241 actor
= call_sbin_request_key
;
242 if (key
->type
->request_key
)
243 actor
= key
->type
->request_key
;
245 ret
= actor(cons
, "create", aux
);
247 /* check that the actor called complete_request_key() prior to
248 * returning an error */
250 !test_bit(KEY_FLAG_REVOKED
, &authkey
->flags
));
254 kleave(" = %d", ret
);
259 * Get the appropriate destination keyring for the request.
261 * The keyring selected is returned with an extra reference upon it which the
262 * caller must release.
264 static void construct_get_dest_keyring(struct key
**_dest_keyring
)
266 struct request_key_auth
*rka
;
267 const struct cred
*cred
= current_cred();
268 struct key
*dest_keyring
= *_dest_keyring
, *authkey
;
270 kenter("%p", dest_keyring
);
272 /* find the appropriate keyring */
274 /* the caller supplied one */
275 key_get(dest_keyring
);
277 /* use a default keyring; falling through the cases until we
278 * find one that we actually have */
279 switch (cred
->jit_keyring
) {
280 case KEY_REQKEY_DEFL_DEFAULT
:
281 case KEY_REQKEY_DEFL_REQUESTOR_KEYRING
:
282 if (cred
->request_key_auth
) {
283 authkey
= cred
->request_key_auth
;
284 down_read(&authkey
->sem
);
285 rka
= authkey
->payload
.data
;
286 if (!test_bit(KEY_FLAG_REVOKED
,
289 key_get(rka
->dest_keyring
);
290 up_read(&authkey
->sem
);
295 case KEY_REQKEY_DEFL_THREAD_KEYRING
:
296 dest_keyring
= key_get(cred
->thread_keyring
);
300 case KEY_REQKEY_DEFL_PROCESS_KEYRING
:
301 dest_keyring
= key_get(cred
->process_keyring
);
305 case KEY_REQKEY_DEFL_SESSION_KEYRING
:
307 dest_keyring
= key_get(
308 rcu_dereference(cred
->session_keyring
));
314 case KEY_REQKEY_DEFL_USER_SESSION_KEYRING
:
316 key_get(cred
->user
->session_keyring
);
319 case KEY_REQKEY_DEFL_USER_KEYRING
:
320 dest_keyring
= key_get(cred
->user
->uid_keyring
);
323 case KEY_REQKEY_DEFL_GROUP_KEYRING
:
329 *_dest_keyring
= dest_keyring
;
330 kleave(" [dk %d]", key_serial(dest_keyring
));
335 * Allocate a new key in under-construction state and attempt to link it in to
336 * the requested keyring.
338 * May return a key that's already under construction instead if there was a
339 * race between two thread calling request_key().
341 static int construct_alloc_key(struct key_type
*type
,
342 const char *description
,
343 struct key
*dest_keyring
,
345 struct key_user
*user
,
348 const struct cred
*cred
= current_cred();
349 unsigned long prealloc
;
355 kenter("%s,%s,,,", type
->name
, description
);
358 mutex_lock(&user
->cons_lock
);
360 perm
= KEY_POS_VIEW
| KEY_POS_SEARCH
| KEY_POS_LINK
| KEY_POS_SETATTR
;
361 perm
|= KEY_USR_VIEW
;
363 perm
|= KEY_POS_READ
;
364 if (type
== &key_type_keyring
|| type
->update
)
365 perm
|= KEY_POS_WRITE
;
367 key
= key_alloc(type
, description
, cred
->fsuid
, cred
->fsgid
, cred
,
372 set_bit(KEY_FLAG_USER_CONSTRUCT
, &key
->flags
);
375 ret
= __key_link_begin(dest_keyring
, type
, description
,
378 goto link_prealloc_failed
;
381 /* attach the key to the destination keyring under lock, but we do need
382 * to do another check just in case someone beat us to it whilst we
383 * waited for locks */
384 mutex_lock(&key_construction_mutex
);
386 key_ref
= search_process_keyrings(type
, description
, type
->match
, cred
);
387 if (!IS_ERR(key_ref
))
388 goto key_already_present
;
391 __key_link(dest_keyring
, key
, &prealloc
);
393 mutex_unlock(&key_construction_mutex
);
395 __key_link_end(dest_keyring
, type
, prealloc
);
396 mutex_unlock(&user
->cons_lock
);
398 kleave(" = 0 [%d]", key_serial(key
));
401 /* the key is now present - we tell the caller that we found it by
402 * returning -EINPROGRESS */
405 mutex_unlock(&key_construction_mutex
);
406 key
= key_ref_to_ptr(key_ref
);
408 ret
= __key_link_check_live_key(dest_keyring
, key
);
410 __key_link(dest_keyring
, key
, &prealloc
);
411 __key_link_end(dest_keyring
, type
, prealloc
);
413 goto link_check_failed
;
415 mutex_unlock(&user
->cons_lock
);
417 kleave(" = -EINPROGRESS [%d]", key_serial(key
));
421 mutex_unlock(&user
->cons_lock
);
423 kleave(" = %d [linkcheck]", ret
);
426 link_prealloc_failed
:
427 mutex_unlock(&user
->cons_lock
);
428 kleave(" = %d [prelink]", ret
);
432 mutex_unlock(&user
->cons_lock
);
433 kleave(" = %ld", PTR_ERR(key
));
438 * Commence key construction.
440 static struct key
*construct_key_and_link(struct key_type
*type
,
441 const char *description
,
442 const char *callout_info
,
445 struct key
*dest_keyring
,
448 struct key_user
*user
;
454 user
= key_user_lookup(current_fsuid());
456 return ERR_PTR(-ENOMEM
);
458 construct_get_dest_keyring(&dest_keyring
);
460 ret
= construct_alloc_key(type
, description
, dest_keyring
, flags
, user
,
465 ret
= construct_key(key
, callout_info
, callout_len
, aux
,
468 kdebug("cons failed");
469 goto construction_failed
;
471 } else if (ret
== -EINPROGRESS
) {
474 goto couldnt_alloc_key
;
477 key_put(dest_keyring
);
478 kleave(" = key %d", key_serial(key
));
482 key_negate_and_link(key
, key_negative_timeout
, NULL
, NULL
);
485 key_put(dest_keyring
);
486 kleave(" = %d", ret
);
491 * request_key_and_link - Request a key and cache it in a keyring.
492 * @type: The type of key we want.
493 * @description: The searchable description of the key.
494 * @callout_info: The data to pass to the instantiation upcall (or NULL).
495 * @callout_len: The length of callout_info.
496 * @aux: Auxiliary data for the upcall.
497 * @dest_keyring: Where to cache the key.
498 * @flags: Flags to key_alloc().
500 * A key matching the specified criteria is searched for in the process's
501 * keyrings and returned with its usage count incremented if found. Otherwise,
502 * if callout_info is not NULL, a key will be allocated and some service
503 * (probably in userspace) will be asked to instantiate it.
505 * If successfully found or created, the key will be linked to the destination
506 * keyring if one is provided.
508 * Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED
509 * or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was
510 * found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT
511 * if insufficient key quota was available to create a new key; or -ENOMEM if
512 * insufficient memory was available.
514 * If the returned key was created, then it may still be under construction,
515 * and wait_for_key_construction() should be used to wait for that to complete.
517 struct key
*request_key_and_link(struct key_type
*type
,
518 const char *description
,
519 const void *callout_info
,
522 struct key
*dest_keyring
,
525 const struct cred
*cred
= current_cred();
530 kenter("%s,%s,%p,%zu,%p,%p,%lx",
531 type
->name
, description
, callout_info
, callout_len
, aux
,
532 dest_keyring
, flags
);
534 /* search all the process keyrings for a key */
535 key_ref
= search_process_keyrings(type
, description
, type
->match
, cred
);
537 if (!IS_ERR(key_ref
)) {
538 key
= key_ref_to_ptr(key_ref
);
540 construct_get_dest_keyring(&dest_keyring
);
541 ret
= key_link(dest_keyring
, key
);
542 key_put(dest_keyring
);
549 } else if (PTR_ERR(key_ref
) != -EAGAIN
) {
550 key
= ERR_CAST(key_ref
);
552 /* the search failed, but the keyrings were searchable, so we
553 * should consult userspace if we can */
554 key
= ERR_PTR(-ENOKEY
);
558 key
= construct_key_and_link(type
, description
, callout_info
,
559 callout_len
, aux
, dest_keyring
,
564 kleave(" = %p", key
);
569 * wait_for_key_construction - Wait for construction of a key to complete
570 * @key: The key being waited for.
571 * @intr: Whether to wait interruptibly.
573 * Wait for a key to finish being constructed.
575 * Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY
576 * if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was
577 * revoked or expired.
579 int wait_for_key_construction(struct key
*key
, bool intr
)
583 ret
= wait_on_bit(&key
->flags
, KEY_FLAG_USER_CONSTRUCT
,
584 intr
? key_wait_bit_intr
: key_wait_bit
,
585 intr
? TASK_INTERRUPTIBLE
: TASK_UNINTERRUPTIBLE
);
588 if (test_bit(KEY_FLAG_NEGATIVE
, &key
->flags
))
589 return key
->type_data
.reject_error
;
590 return key_validate(key
);
592 EXPORT_SYMBOL(wait_for_key_construction
);
595 * request_key - Request a key and wait for construction
596 * @type: Type of key.
597 * @description: The searchable description of the key.
598 * @callout_info: The data to pass to the instantiation upcall (or NULL).
600 * As for request_key_and_link() except that it does not add the returned key
601 * to a keyring if found, new keys are always allocated in the user's quota,
602 * the callout_info must be a NUL-terminated string and no auxiliary data can
605 * Furthermore, it then works as wait_for_key_construction() to wait for the
606 * completion of keys undergoing construction with a non-interruptible wait.
608 struct key
*request_key(struct key_type
*type
,
609 const char *description
,
610 const char *callout_info
)
613 size_t callout_len
= 0;
617 callout_len
= strlen(callout_info
);
618 key
= request_key_and_link(type
, description
, callout_info
, callout_len
,
619 NULL
, NULL
, KEY_ALLOC_IN_QUOTA
);
621 ret
= wait_for_key_construction(key
, false);
629 EXPORT_SYMBOL(request_key
);
632 * request_key_with_auxdata - Request a key with auxiliary data for the upcaller
633 * @type: The type of key we want.
634 * @description: The searchable description of the key.
635 * @callout_info: The data to pass to the instantiation upcall (or NULL).
636 * @callout_len: The length of callout_info.
637 * @aux: Auxiliary data for the upcall.
639 * As for request_key_and_link() except that it does not add the returned key
640 * to a keyring if found and new keys are always allocated in the user's quota.
642 * Furthermore, it then works as wait_for_key_construction() to wait for the
643 * completion of keys undergoing construction with a non-interruptible wait.
645 struct key
*request_key_with_auxdata(struct key_type
*type
,
646 const char *description
,
647 const void *callout_info
,
654 key
= request_key_and_link(type
, description
, callout_info
, callout_len
,
655 aux
, NULL
, KEY_ALLOC_IN_QUOTA
);
657 ret
= wait_for_key_construction(key
, false);
665 EXPORT_SYMBOL(request_key_with_auxdata
);
668 * request_key_async - Request a key (allow async construction)
669 * @type: Type of key.
670 * @description: The searchable description of the key.
671 * @callout_info: The data to pass to the instantiation upcall (or NULL).
672 * @callout_len: The length of callout_info.
674 * As for request_key_and_link() except that it does not add the returned key
675 * to a keyring if found, new keys are always allocated in the user's quota and
676 * no auxiliary data can be passed.
678 * The caller should call wait_for_key_construction() to wait for the
679 * completion of the returned key if it is still undergoing construction.
681 struct key
*request_key_async(struct key_type
*type
,
682 const char *description
,
683 const void *callout_info
,
686 return request_key_and_link(type
, description
, callout_info
,
687 callout_len
, NULL
, NULL
,
690 EXPORT_SYMBOL(request_key_async
);
693 * request a key with auxiliary data for the upcaller (allow async construction)
694 * @type: Type of key.
695 * @description: The searchable description of the key.
696 * @callout_info: The data to pass to the instantiation upcall (or NULL).
697 * @callout_len: The length of callout_info.
698 * @aux: Auxiliary data for the upcall.
700 * As for request_key_and_link() except that it does not add the returned key
701 * to a keyring if found and new keys are always allocated in the user's quota.
703 * The caller should call wait_for_key_construction() to wait for the
704 * completion of the returned key if it is still undergoing construction.
706 struct key
*request_key_async_with_auxdata(struct key_type
*type
,
707 const char *description
,
708 const void *callout_info
,
712 return request_key_and_link(type
, description
, callout_info
,
713 callout_len
, aux
, NULL
, KEY_ALLOC_IN_QUOTA
);
715 EXPORT_SYMBOL(request_key_async_with_auxdata
);