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)
76 struct cred *cred = (struct cred*)current_cred();
77 struct key *keyring = info->data;
79 return install_session_keyring_to_cred(cred, keyring);
83 * Clean up a usermode helper with session keyring.
85 static void umh_keys_cleanup(struct subprocess_info *info)
87 struct key *keyring = info->data;
92 * Call a usermode helper with a specific session keyring.
94 static int call_usermodehelper_keys(char *path, char **argv, char **envp,
95 struct key *session_keyring, enum umh_wait wait)
97 gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
98 struct subprocess_info *info =
99 call_usermodehelper_setup(path, argv, envp, gfp_mask);
104 call_usermodehelper_setfns(info, umh_keys_init, umh_keys_cleanup,
105 key_get(session_keyring));
106 return call_usermodehelper_exec(info, wait);
110 * Request userspace finish the construction of a key
111 * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
113 static int call_sbin_request_key(struct key_construction *cons,
117 const struct cred *cred = current_cred();
118 key_serial_t prkey, sskey;
119 struct key *key = cons->key, *authkey = cons->authkey, *keyring,
121 char *argv[9], *envp[3], uid_str[12], gid_str[12];
122 char key_str[12], keyring_str[3][12];
126 kenter("{%d},{%d},%s", key->serial, authkey->serial, op);
128 ret = install_user_keyrings();
132 /* allocate a new session keyring */
133 sprintf(desc, "_req.%u", key->serial);
135 cred = get_current_cred();
136 keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred,
137 KEY_ALLOC_QUOTA_OVERRUN, NULL);
139 if (IS_ERR(keyring)) {
140 ret = PTR_ERR(keyring);
144 /* attach the auth key to the session keyring */
145 ret = key_link(keyring, authkey);
149 /* record the UID and GID */
150 sprintf(uid_str, "%d", cred->fsuid);
151 sprintf(gid_str, "%d", cred->fsgid);
153 /* we say which key is under construction */
154 sprintf(key_str, "%d", key->serial);
156 /* we specify the process's default keyrings */
157 sprintf(keyring_str[0], "%d",
158 cred->thread_keyring ? cred->thread_keyring->serial : 0);
161 if (cred->tgcred->process_keyring)
162 prkey = cred->tgcred->process_keyring->serial;
163 sprintf(keyring_str[1], "%d", prkey);
166 session = rcu_dereference(cred->tgcred->session_keyring);
168 session = cred->user->session_keyring;
169 sskey = session->serial;
172 sprintf(keyring_str[2], "%d", sskey);
174 /* set up a minimal environment */
176 envp[i++] = "HOME=/";
177 envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
180 /* set up the argument list */
182 argv[i++] = "/sbin/request-key";
183 argv[i++] = (char *) op;
187 argv[i++] = keyring_str[0];
188 argv[i++] = keyring_str[1];
189 argv[i++] = keyring_str[2];
193 ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
195 kdebug("usermode -> 0x%x", ret);
197 /* ret is the exit/wait code */
198 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
199 key_validate(key) < 0)
202 /* ignore any errors from userspace if the key was
211 complete_request_key(cons, ret);
212 kleave(" = %d", ret);
217 * Call out to userspace for key construction.
219 * Program failure is ignored in favour of key status.
221 static int construct_key(struct key *key, const void *callout_info,
222 size_t callout_len, void *aux,
223 struct key *dest_keyring)
225 struct key_construction *cons;
226 request_key_actor_t actor;
230 kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
232 cons = kmalloc(sizeof(*cons), GFP_KERNEL);
236 /* allocate an authorisation key */
237 authkey = request_key_auth_new(key, callout_info, callout_len,
239 if (IS_ERR(authkey)) {
241 ret = PTR_ERR(authkey);
244 cons->authkey = key_get(authkey);
245 cons->key = key_get(key);
248 actor = call_sbin_request_key;
249 if (key->type->request_key)
250 actor = key->type->request_key;
252 ret = actor(cons, "create", aux);
254 /* check that the actor called complete_request_key() prior to
255 * returning an error */
257 !test_bit(KEY_FLAG_REVOKED, &authkey->flags));
261 kleave(" = %d", ret);
266 * Get the appropriate destination keyring for the request.
268 * The keyring selected is returned with an extra reference upon it which the
269 * caller must release.
271 static void construct_get_dest_keyring(struct key **_dest_keyring)
273 struct request_key_auth *rka;
274 const struct cred *cred = current_cred();
275 struct key *dest_keyring = *_dest_keyring, *authkey;
277 kenter("%p", dest_keyring);
279 /* find the appropriate keyring */
281 /* the caller supplied one */
282 key_get(dest_keyring);
284 /* use a default keyring; falling through the cases until we
285 * find one that we actually have */
286 switch (cred->jit_keyring) {
287 case KEY_REQKEY_DEFL_DEFAULT:
288 case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
289 if (cred->request_key_auth) {
290 authkey = cred->request_key_auth;
291 down_read(&authkey->sem);
292 rka = authkey->payload.data;
293 if (!test_bit(KEY_FLAG_REVOKED,
296 key_get(rka->dest_keyring);
297 up_read(&authkey->sem);
302 case KEY_REQKEY_DEFL_THREAD_KEYRING:
303 dest_keyring = key_get(cred->thread_keyring);
307 case KEY_REQKEY_DEFL_PROCESS_KEYRING:
308 dest_keyring = key_get(cred->tgcred->process_keyring);
312 case KEY_REQKEY_DEFL_SESSION_KEYRING:
314 dest_keyring = key_get(
315 rcu_dereference(cred->tgcred->session_keyring));
321 case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
323 key_get(cred->user->session_keyring);
326 case KEY_REQKEY_DEFL_USER_KEYRING:
327 dest_keyring = key_get(cred->user->uid_keyring);
330 case KEY_REQKEY_DEFL_GROUP_KEYRING:
336 *_dest_keyring = dest_keyring;
337 kleave(" [dk %d]", key_serial(dest_keyring));
342 * Allocate a new key in under-construction state and attempt to link it in to
343 * the requested keyring.
345 * May return a key that's already under construction instead if there was a
346 * race between two thread calling request_key().
348 static int construct_alloc_key(struct key_type *type,
349 const char *description,
350 struct key *dest_keyring,
352 struct key_user *user,
355 const struct cred *cred = current_cred();
356 unsigned long prealloc;
361 kenter("%s,%s,,,", type->name, description);
364 mutex_lock(&user->cons_lock);
366 key = key_alloc(type, description, cred->fsuid, cred->fsgid, cred,
371 set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
374 ret = __key_link_begin(dest_keyring, type, description,
377 goto link_prealloc_failed;
380 /* attach the key to the destination keyring under lock, but we do need
381 * to do another check just in case someone beat us to it whilst we
382 * waited for locks */
383 mutex_lock(&key_construction_mutex);
385 key_ref = search_process_keyrings(type, description, type->match, cred);
386 if (!IS_ERR(key_ref))
387 goto key_already_present;
390 __key_link(dest_keyring, key, &prealloc);
392 mutex_unlock(&key_construction_mutex);
394 __key_link_end(dest_keyring, type, prealloc);
395 mutex_unlock(&user->cons_lock);
397 kleave(" = 0 [%d]", key_serial(key));
400 /* the key is now present - we tell the caller that we found it by
401 * returning -EINPROGRESS */
404 mutex_unlock(&key_construction_mutex);
405 key = key_ref_to_ptr(key_ref);
407 ret = __key_link_check_live_key(dest_keyring, key);
409 __key_link(dest_keyring, key, &prealloc);
410 __key_link_end(dest_keyring, type, prealloc);
412 goto link_check_failed;
414 mutex_unlock(&user->cons_lock);
416 kleave(" = -EINPROGRESS [%d]", key_serial(key));
420 mutex_unlock(&user->cons_lock);
422 kleave(" = %d [linkcheck]", ret);
425 link_prealloc_failed:
426 mutex_unlock(&user->cons_lock);
427 kleave(" = %d [prelink]", ret);
431 mutex_unlock(&user->cons_lock);
432 kleave(" = %ld", PTR_ERR(key));
437 * Commence key construction.
439 static struct key *construct_key_and_link(struct key_type *type,
440 const char *description,
441 const char *callout_info,
444 struct key *dest_keyring,
447 struct key_user *user;
453 user = key_user_lookup(current_fsuid(), current_user_ns());
455 return ERR_PTR(-ENOMEM);
457 construct_get_dest_keyring(&dest_keyring);
459 ret = construct_alloc_key(type, description, dest_keyring, flags, user,
464 ret = construct_key(key, callout_info, callout_len, aux,
467 kdebug("cons failed");
468 goto construction_failed;
470 } else if (ret == -EINPROGRESS) {
476 key_put(dest_keyring);
477 kleave(" = key %d", key_serial(key));
481 key_negate_and_link(key, key_negative_timeout, NULL, NULL);
483 key_put(dest_keyring);
484 kleave(" = %d", ret);
489 * request_key_and_link - Request a key and cache it in a keyring.
490 * @type: The type of key we want.
491 * @description: The searchable description of the key.
492 * @callout_info: The data to pass to the instantiation upcall (or NULL).
493 * @callout_len: The length of callout_info.
494 * @aux: Auxiliary data for the upcall.
495 * @dest_keyring: Where to cache the key.
496 * @flags: Flags to key_alloc().
498 * A key matching the specified criteria is searched for in the process's
499 * keyrings and returned with its usage count incremented if found. Otherwise,
500 * if callout_info is not NULL, a key will be allocated and some service
501 * (probably in userspace) will be asked to instantiate it.
503 * If successfully found or created, the key will be linked to the destination
504 * keyring if one is provided.
506 * Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED
507 * or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was
508 * found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT
509 * if insufficient key quota was available to create a new key; or -ENOMEM if
510 * insufficient memory was available.
512 * If the returned key was created, then it may still be under construction,
513 * and wait_for_key_construction() should be used to wait for that to complete.
515 struct key *request_key_and_link(struct key_type *type,
516 const char *description,
517 const void *callout_info,
520 struct key *dest_keyring,
523 const struct cred *cred = current_cred();
528 kenter("%s,%s,%p,%zu,%p,%p,%lx",
529 type->name, description, callout_info, callout_len, aux,
530 dest_keyring, flags);
532 /* search all the process keyrings for a key */
533 key_ref = search_process_keyrings(type, description, type->match, cred);
535 if (!IS_ERR(key_ref)) {
536 key = key_ref_to_ptr(key_ref);
538 construct_get_dest_keyring(&dest_keyring);
539 ret = key_link(dest_keyring, key);
540 key_put(dest_keyring);
547 } else if (PTR_ERR(key_ref) != -EAGAIN) {
548 key = ERR_CAST(key_ref);
550 /* the search failed, but the keyrings were searchable, so we
551 * should consult userspace if we can */
552 key = ERR_PTR(-ENOKEY);
556 key = construct_key_and_link(type, description, callout_info,
557 callout_len, aux, dest_keyring,
562 kleave(" = %p", key);
567 * wait_for_key_construction - Wait for construction of a key to complete
568 * @key: The key being waited for.
569 * @intr: Whether to wait interruptibly.
571 * Wait for a key to finish being constructed.
573 * Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY
574 * if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was
575 * revoked or expired.
577 int wait_for_key_construction(struct key *key, bool intr)
581 ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
582 intr ? key_wait_bit_intr : key_wait_bit,
583 intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
586 if (test_bit(KEY_FLAG_NEGATIVE, &key->flags))
587 return key->type_data.reject_error;
588 return key_validate(key);
590 EXPORT_SYMBOL(wait_for_key_construction);
593 * request_key - Request a key and wait for construction
594 * @type: Type of key.
595 * @description: The searchable description of the key.
596 * @callout_info: The data to pass to the instantiation upcall (or NULL).
598 * As for request_key_and_link() except that it does not add the returned key
599 * to a keyring if found, new keys are always allocated in the user's quota,
600 * the callout_info must be a NUL-terminated string and no auxiliary data can
603 * Furthermore, it then works as wait_for_key_construction() to wait for the
604 * completion of keys undergoing construction with a non-interruptible wait.
606 struct key *request_key(struct key_type *type,
607 const char *description,
608 const char *callout_info)
611 size_t callout_len = 0;
615 callout_len = strlen(callout_info);
616 key = request_key_and_link(type, description, callout_info, callout_len,
617 NULL, NULL, KEY_ALLOC_IN_QUOTA);
619 ret = wait_for_key_construction(key, false);
627 EXPORT_SYMBOL(request_key);
630 * request_key_with_auxdata - Request a key with auxiliary data for the upcaller
631 * @type: The type of key we want.
632 * @description: The searchable description of the key.
633 * @callout_info: The data to pass to the instantiation upcall (or NULL).
634 * @callout_len: The length of callout_info.
635 * @aux: Auxiliary data for the upcall.
637 * As for request_key_and_link() except that it does not add the returned key
638 * to a keyring if found and new keys are always allocated in the user's quota.
640 * Furthermore, it then works as wait_for_key_construction() to wait for the
641 * completion of keys undergoing construction with a non-interruptible wait.
643 struct key *request_key_with_auxdata(struct key_type *type,
644 const char *description,
645 const void *callout_info,
652 key = request_key_and_link(type, description, callout_info, callout_len,
653 aux, NULL, KEY_ALLOC_IN_QUOTA);
655 ret = wait_for_key_construction(key, false);
663 EXPORT_SYMBOL(request_key_with_auxdata);
666 * request_key_async - Request a key (allow async construction)
667 * @type: Type of key.
668 * @description: The searchable description of the key.
669 * @callout_info: The data to pass to the instantiation upcall (or NULL).
670 * @callout_len: The length of callout_info.
672 * As for request_key_and_link() except that it does not add the returned key
673 * to a keyring if found, new keys are always allocated in the user's quota and
674 * no auxiliary data can be passed.
676 * The caller should call wait_for_key_construction() to wait for the
677 * completion of the returned key if it is still undergoing construction.
679 struct key *request_key_async(struct key_type *type,
680 const char *description,
681 const void *callout_info,
684 return request_key_and_link(type, description, callout_info,
685 callout_len, NULL, NULL,
688 EXPORT_SYMBOL(request_key_async);
691 * request a key with auxiliary data for the upcaller (allow async construction)
692 * @type: Type of key.
693 * @description: The searchable description of the key.
694 * @callout_info: The data to pass to the instantiation upcall (or NULL).
695 * @callout_len: The length of callout_info.
696 * @aux: Auxiliary data for the upcall.
698 * As for request_key_and_link() except that it does not add the returned key
699 * to a keyring if found and new keys are always allocated in the user's quota.
701 * The caller should call wait_for_key_construction() to wait for the
702 * completion of the returned key if it is still undergoing construction.
704 struct key *request_key_async_with_auxdata(struct key_type *type,
705 const char *description,
706 const void *callout_info,
710 return request_key_and_link(type, description, callout_info,
711 callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA);
713 EXPORT_SYMBOL(request_key_async_with_auxdata);