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);