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 struct subprocess_info *info;
98 info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL,
99 umh_keys_init, umh_keys_cleanup,
104 key_get(session_keyring);
105 return call_usermodehelper_exec(info, wait);
109 * Request userspace finish the construction of a key
110 * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
112 static int call_sbin_request_key(struct key_construction *cons,
116 const struct cred *cred = current_cred();
117 key_serial_t prkey, sskey;
118 struct key *key = cons->key, *authkey = cons->authkey, *keyring,
120 char *argv[9], *envp[3], uid_str[12], gid_str[12];
121 char key_str[12], keyring_str[3][12];
125 kenter("{%d},{%d},%s", key->serial, authkey->serial, op);
127 ret = install_user_keyrings();
131 /* allocate a new session keyring */
132 sprintf(desc, "_req.%u", key->serial);
134 cred = get_current_cred();
135 keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred,
136 KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
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", from_kuid(&init_user_ns, cred->fsuid));
151 sprintf(gid_str, "%d", from_kgid(&init_user_ns, 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->process_keyring)
162 prkey = cred->process_keyring->serial;
163 sprintf(keyring_str[1], "%d", prkey);
166 session = rcu_dereference(cred->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->process_keyring);
312 case KEY_REQKEY_DEFL_SESSION_KEYRING:
314 dest_keyring = key_get(
315 rcu_dereference(cred->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 keyring_search_context *ctx,
349 struct key *dest_keyring,
351 struct key_user *user,
354 struct assoc_array_edit *edit;
361 ctx->index_key.type->name, ctx->index_key.description);
364 mutex_lock(&user->cons_lock);
366 perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
367 perm |= KEY_USR_VIEW;
368 if (ctx->index_key.type->read)
369 perm |= KEY_POS_READ;
370 if (ctx->index_key.type == &key_type_keyring ||
371 ctx->index_key.type->update)
372 perm |= KEY_POS_WRITE;
374 key = key_alloc(ctx->index_key.type, ctx->index_key.description,
375 ctx->cred->fsuid, ctx->cred->fsgid, ctx->cred,
380 set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
383 ret = __key_link_begin(dest_keyring, &ctx->index_key, &edit);
385 goto link_prealloc_failed;
388 /* attach the key to the destination keyring under lock, but we do need
389 * to do another check just in case someone beat us to it whilst we
390 * waited for locks */
391 mutex_lock(&key_construction_mutex);
393 key_ref = search_process_keyrings(ctx);
394 if (!IS_ERR(key_ref))
395 goto key_already_present;
398 __key_link(key, &edit);
400 mutex_unlock(&key_construction_mutex);
402 __key_link_end(dest_keyring, &ctx->index_key, edit);
403 mutex_unlock(&user->cons_lock);
405 kleave(" = 0 [%d]", key_serial(key));
408 /* the key is now present - we tell the caller that we found it by
409 * returning -EINPROGRESS */
412 mutex_unlock(&key_construction_mutex);
413 key = key_ref_to_ptr(key_ref);
415 ret = __key_link_check_live_key(dest_keyring, key);
417 __key_link(key, &edit);
418 __key_link_end(dest_keyring, &ctx->index_key, edit);
420 goto link_check_failed;
422 mutex_unlock(&user->cons_lock);
424 kleave(" = -EINPROGRESS [%d]", key_serial(key));
428 mutex_unlock(&user->cons_lock);
430 kleave(" = %d [linkcheck]", ret);
433 link_prealloc_failed:
434 mutex_unlock(&user->cons_lock);
435 kleave(" = %d [prelink]", ret);
439 mutex_unlock(&user->cons_lock);
440 kleave(" = %ld", PTR_ERR(key));
445 * Commence key construction.
447 static struct key *construct_key_and_link(struct keyring_search_context *ctx,
448 const char *callout_info,
451 struct key *dest_keyring,
454 struct key_user *user;
460 user = key_user_lookup(current_fsuid());
462 return ERR_PTR(-ENOMEM);
464 construct_get_dest_keyring(&dest_keyring);
466 ret = construct_alloc_key(ctx, dest_keyring, flags, user, &key);
470 ret = construct_key(key, callout_info, callout_len, aux,
473 kdebug("cons failed");
474 goto construction_failed;
476 } else if (ret == -EINPROGRESS) {
479 goto couldnt_alloc_key;
482 key_put(dest_keyring);
483 kleave(" = key %d", key_serial(key));
487 key_negate_and_link(key, key_negative_timeout, NULL, NULL);
490 key_put(dest_keyring);
491 kleave(" = %d", ret);
496 * request_key_and_link - Request a key and cache it in a keyring.
497 * @type: The type of key we want.
498 * @description: The searchable description of the key.
499 * @callout_info: The data to pass to the instantiation upcall (or NULL).
500 * @callout_len: The length of callout_info.
501 * @aux: Auxiliary data for the upcall.
502 * @dest_keyring: Where to cache the key.
503 * @flags: Flags to key_alloc().
505 * A key matching the specified criteria is searched for in the process's
506 * keyrings and returned with its usage count incremented if found. Otherwise,
507 * if callout_info is not NULL, a key will be allocated and some service
508 * (probably in userspace) will be asked to instantiate it.
510 * If successfully found or created, the key will be linked to the destination
511 * keyring if one is provided.
513 * Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED
514 * or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was
515 * found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT
516 * if insufficient key quota was available to create a new key; or -ENOMEM if
517 * insufficient memory was available.
519 * If the returned key was created, then it may still be under construction,
520 * and wait_for_key_construction() should be used to wait for that to complete.
522 struct key *request_key_and_link(struct key_type *type,
523 const char *description,
524 const void *callout_info,
527 struct key *dest_keyring,
530 struct keyring_search_context ctx = {
531 .index_key.type = type,
532 .index_key.description = description,
533 .cred = current_cred(),
534 .match = type->match,
535 .match_data = description,
536 .flags = KEYRING_SEARCH_LOOKUP_DIRECT,
542 kenter("%s,%s,%p,%zu,%p,%p,%lx",
543 ctx.index_key.type->name, ctx.index_key.description,
544 callout_info, callout_len, aux, dest_keyring, flags);
546 /* search all the process keyrings for a key */
547 key_ref = search_process_keyrings(&ctx);
549 if (!IS_ERR(key_ref)) {
550 key = key_ref_to_ptr(key_ref);
552 construct_get_dest_keyring(&dest_keyring);
553 ret = key_link(dest_keyring, key);
554 key_put(dest_keyring);
561 } else if (PTR_ERR(key_ref) != -EAGAIN) {
562 key = ERR_CAST(key_ref);
564 /* the search failed, but the keyrings were searchable, so we
565 * should consult userspace if we can */
566 key = ERR_PTR(-ENOKEY);
570 key = construct_key_and_link(&ctx, callout_info, callout_len,
571 aux, dest_keyring, flags);
575 kleave(" = %p", key);
580 * wait_for_key_construction - Wait for construction of a key to complete
581 * @key: The key being waited for.
582 * @intr: Whether to wait interruptibly.
584 * Wait for a key to finish being constructed.
586 * Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY
587 * if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was
588 * revoked or expired.
590 int wait_for_key_construction(struct key *key, bool intr)
594 ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
595 intr ? key_wait_bit_intr : key_wait_bit,
596 intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
599 if (test_bit(KEY_FLAG_NEGATIVE, &key->flags)) {
601 return key->type_data.reject_error;
603 return key_validate(key);
605 EXPORT_SYMBOL(wait_for_key_construction);
608 * request_key - Request a key and wait for construction
609 * @type: Type of key.
610 * @description: The searchable description of the key.
611 * @callout_info: The data to pass to the instantiation upcall (or NULL).
613 * As for request_key_and_link() except that it does not add the returned key
614 * to a keyring if found, new keys are always allocated in the user's quota,
615 * the callout_info must be a NUL-terminated string and no auxiliary data can
618 * Furthermore, it then works as wait_for_key_construction() to wait for the
619 * completion of keys undergoing construction with a non-interruptible wait.
621 struct key *request_key(struct key_type *type,
622 const char *description,
623 const char *callout_info)
626 size_t callout_len = 0;
630 callout_len = strlen(callout_info);
631 key = request_key_and_link(type, description, callout_info, callout_len,
632 NULL, NULL, KEY_ALLOC_IN_QUOTA);
634 ret = wait_for_key_construction(key, false);
642 EXPORT_SYMBOL(request_key);
645 * request_key_with_auxdata - Request a key with auxiliary data for the upcaller
646 * @type: The type of key we want.
647 * @description: The searchable description of the key.
648 * @callout_info: The data to pass to the instantiation upcall (or NULL).
649 * @callout_len: The length of callout_info.
650 * @aux: Auxiliary data for the upcall.
652 * As for request_key_and_link() except that it does not add the returned key
653 * to a keyring if found and new keys are always allocated in the user's quota.
655 * Furthermore, it then works as wait_for_key_construction() to wait for the
656 * completion of keys undergoing construction with a non-interruptible wait.
658 struct key *request_key_with_auxdata(struct key_type *type,
659 const char *description,
660 const void *callout_info,
667 key = request_key_and_link(type, description, callout_info, callout_len,
668 aux, NULL, KEY_ALLOC_IN_QUOTA);
670 ret = wait_for_key_construction(key, false);
678 EXPORT_SYMBOL(request_key_with_auxdata);
681 * request_key_async - Request a key (allow async construction)
682 * @type: Type of key.
683 * @description: The searchable description of the key.
684 * @callout_info: The data to pass to the instantiation upcall (or NULL).
685 * @callout_len: The length of callout_info.
687 * As for request_key_and_link() except that it does not add the returned key
688 * to a keyring if found, new keys are always allocated in the user's quota and
689 * no auxiliary data can be passed.
691 * The caller should call wait_for_key_construction() to wait for the
692 * completion of the returned key if it is still undergoing construction.
694 struct key *request_key_async(struct key_type *type,
695 const char *description,
696 const void *callout_info,
699 return request_key_and_link(type, description, callout_info,
700 callout_len, NULL, NULL,
703 EXPORT_SYMBOL(request_key_async);
706 * request a key with auxiliary data for the upcaller (allow async construction)
707 * @type: Type of key.
708 * @description: The searchable description of the key.
709 * @callout_info: The data to pass to the instantiation upcall (or NULL).
710 * @callout_len: The length of callout_info.
711 * @aux: Auxiliary data for the upcall.
713 * As for request_key_and_link() except that it does not add the returned key
714 * to a keyring if found and new keys are always allocated in the user's quota.
716 * The caller should call wait_for_key_construction() to wait for the
717 * completion of the returned key if it is still undergoing construction.
719 struct key *request_key_async_with_auxdata(struct key_type *type,
720 const char *description,
721 const void *callout_info,
725 return request_key_and_link(type, description, callout_info,
726 callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA);
728 EXPORT_SYMBOL(request_key_async_with_auxdata);