Merge branch 'for-3.2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj...
[zen-stable.git] / security / keys / request_key.c
blob82465328c39b94b5264fb65ba27399f6cdf4d68f
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>
20 #include "internal.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)
29 schedule();
30 return 0;
34 * wait_on_bit() sleep function for interruptible waiting
36 static int key_wait_bit_intr(void *flags)
38 schedule();
39 return signal_pending(current) ? -ERESTARTSYS : 0;
42 /**
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
49 * unconditionally.
51 void complete_request_key(struct key_construction *cons, int error)
53 kenter("{%d,%d},%d", cons->key->serial, cons->authkey->serial, error);
55 if (error < 0)
56 key_negate_and_link(cons->key, key_negative_timeout, NULL,
57 cons->authkey);
58 else
59 key_revoke(cons->authkey);
61 key_put(cons->key);
62 key_put(cons->authkey);
63 kfree(cons);
65 EXPORT_SYMBOL(complete_request_key);
68 * Initialise a usermode helper that is going to have a specific session
69 * keyring.
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;
87 key_put(keyring);
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, enum umh_wait wait)
96 gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
97 struct subprocess_info *info =
98 call_usermodehelper_setup(path, argv, envp, gfp_mask);
100 if (!info)
101 return -ENOMEM;
103 call_usermodehelper_setfns(info, 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,
113 const char *op,
114 void *aux)
116 const struct cred *cred = current_cred();
117 key_serial_t prkey, sskey;
118 struct key *key = cons->key, *authkey = cons->authkey, *keyring,
119 *session;
120 char *argv[9], *envp[3], uid_str[12], gid_str[12];
121 char key_str[12], keyring_str[3][12];
122 char desc[20];
123 int ret, i;
125 kenter("{%d},{%d},%s", key->serial, authkey->serial, op);
127 ret = install_user_keyrings();
128 if (ret < 0)
129 goto error_alloc;
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_ALLOC_QUOTA_OVERRUN, NULL);
137 put_cred(cred);
138 if (IS_ERR(keyring)) {
139 ret = PTR_ERR(keyring);
140 goto error_alloc;
143 /* attach the auth key to the session keyring */
144 ret = key_link(keyring, authkey);
145 if (ret < 0)
146 goto error_link;
148 /* record the UID and GID */
149 sprintf(uid_str, "%d", cred->fsuid);
150 sprintf(gid_str, "%d", cred->fsgid);
152 /* we say which key is under construction */
153 sprintf(key_str, "%d", key->serial);
155 /* we specify the process's default keyrings */
156 sprintf(keyring_str[0], "%d",
157 cred->thread_keyring ? cred->thread_keyring->serial : 0);
159 prkey = 0;
160 if (cred->tgcred->process_keyring)
161 prkey = cred->tgcred->process_keyring->serial;
162 sprintf(keyring_str[1], "%d", prkey);
164 rcu_read_lock();
165 session = rcu_dereference(cred->tgcred->session_keyring);
166 if (!session)
167 session = cred->user->session_keyring;
168 sskey = session->serial;
169 rcu_read_unlock();
171 sprintf(keyring_str[2], "%d", sskey);
173 /* set up a minimal environment */
174 i = 0;
175 envp[i++] = "HOME=/";
176 envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
177 envp[i] = NULL;
179 /* set up the argument list */
180 i = 0;
181 argv[i++] = "/sbin/request-key";
182 argv[i++] = (char *) op;
183 argv[i++] = key_str;
184 argv[i++] = uid_str;
185 argv[i++] = gid_str;
186 argv[i++] = keyring_str[0];
187 argv[i++] = keyring_str[1];
188 argv[i++] = keyring_str[2];
189 argv[i] = NULL;
191 /* do it */
192 ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
193 UMH_WAIT_PROC);
194 kdebug("usermode -> 0x%x", ret);
195 if (ret >= 0) {
196 /* ret is the exit/wait code */
197 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
198 key_validate(key) < 0)
199 ret = -ENOKEY;
200 else
201 /* ignore any errors from userspace if the key was
202 * instantiated */
203 ret = 0;
206 error_link:
207 key_put(keyring);
209 error_alloc:
210 complete_request_key(cons, ret);
211 kleave(" = %d", ret);
212 return ret;
216 * Call out to userspace for key construction.
218 * Program failure is ignored in favour of key status.
220 static int construct_key(struct key *key, const void *callout_info,
221 size_t callout_len, void *aux,
222 struct key *dest_keyring)
224 struct key_construction *cons;
225 request_key_actor_t actor;
226 struct key *authkey;
227 int ret;
229 kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
231 cons = kmalloc(sizeof(*cons), GFP_KERNEL);
232 if (!cons)
233 return -ENOMEM;
235 /* allocate an authorisation key */
236 authkey = request_key_auth_new(key, callout_info, callout_len,
237 dest_keyring);
238 if (IS_ERR(authkey)) {
239 kfree(cons);
240 ret = PTR_ERR(authkey);
241 authkey = NULL;
242 } else {
243 cons->authkey = key_get(authkey);
244 cons->key = key_get(key);
246 /* make the call */
247 actor = call_sbin_request_key;
248 if (key->type->request_key)
249 actor = key->type->request_key;
251 ret = actor(cons, "create", aux);
253 /* check that the actor called complete_request_key() prior to
254 * returning an error */
255 WARN_ON(ret < 0 &&
256 !test_bit(KEY_FLAG_REVOKED, &authkey->flags));
257 key_put(authkey);
260 kleave(" = %d", ret);
261 return ret;
265 * Get the appropriate destination keyring for the request.
267 * The keyring selected is returned with an extra reference upon it which the
268 * caller must release.
270 static void construct_get_dest_keyring(struct key **_dest_keyring)
272 struct request_key_auth *rka;
273 const struct cred *cred = current_cred();
274 struct key *dest_keyring = *_dest_keyring, *authkey;
276 kenter("%p", dest_keyring);
278 /* find the appropriate keyring */
279 if (dest_keyring) {
280 /* the caller supplied one */
281 key_get(dest_keyring);
282 } else {
283 /* use a default keyring; falling through the cases until we
284 * find one that we actually have */
285 switch (cred->jit_keyring) {
286 case KEY_REQKEY_DEFL_DEFAULT:
287 case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
288 if (cred->request_key_auth) {
289 authkey = cred->request_key_auth;
290 down_read(&authkey->sem);
291 rka = authkey->payload.data;
292 if (!test_bit(KEY_FLAG_REVOKED,
293 &authkey->flags))
294 dest_keyring =
295 key_get(rka->dest_keyring);
296 up_read(&authkey->sem);
297 if (dest_keyring)
298 break;
301 case KEY_REQKEY_DEFL_THREAD_KEYRING:
302 dest_keyring = key_get(cred->thread_keyring);
303 if (dest_keyring)
304 break;
306 case KEY_REQKEY_DEFL_PROCESS_KEYRING:
307 dest_keyring = key_get(cred->tgcred->process_keyring);
308 if (dest_keyring)
309 break;
311 case KEY_REQKEY_DEFL_SESSION_KEYRING:
312 rcu_read_lock();
313 dest_keyring = key_get(
314 rcu_dereference(cred->tgcred->session_keyring));
315 rcu_read_unlock();
317 if (dest_keyring)
318 break;
320 case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
321 dest_keyring =
322 key_get(cred->user->session_keyring);
323 break;
325 case KEY_REQKEY_DEFL_USER_KEYRING:
326 dest_keyring = key_get(cred->user->uid_keyring);
327 break;
329 case KEY_REQKEY_DEFL_GROUP_KEYRING:
330 default:
331 BUG();
335 *_dest_keyring = dest_keyring;
336 kleave(" [dk %d]", key_serial(dest_keyring));
337 return;
341 * Allocate a new key in under-construction state and attempt to link it in to
342 * the requested keyring.
344 * May return a key that's already under construction instead if there was a
345 * race between two thread calling request_key().
347 static int construct_alloc_key(struct key_type *type,
348 const char *description,
349 struct key *dest_keyring,
350 unsigned long flags,
351 struct key_user *user,
352 struct key **_key)
354 const struct cred *cred = current_cred();
355 unsigned long prealloc;
356 struct key *key;
357 key_ref_t key_ref;
358 int ret;
360 kenter("%s,%s,,,", type->name, description);
362 *_key = NULL;
363 mutex_lock(&user->cons_lock);
365 key = key_alloc(type, description, cred->fsuid, cred->fsgid, cred,
366 KEY_POS_ALL, flags);
367 if (IS_ERR(key))
368 goto alloc_failed;
370 set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
372 if (dest_keyring) {
373 ret = __key_link_begin(dest_keyring, type, description,
374 &prealloc);
375 if (ret < 0)
376 goto link_prealloc_failed;
379 /* attach the key to the destination keyring under lock, but we do need
380 * to do another check just in case someone beat us to it whilst we
381 * waited for locks */
382 mutex_lock(&key_construction_mutex);
384 key_ref = search_process_keyrings(type, description, type->match, cred);
385 if (!IS_ERR(key_ref))
386 goto key_already_present;
388 if (dest_keyring)
389 __key_link(dest_keyring, key, &prealloc);
391 mutex_unlock(&key_construction_mutex);
392 if (dest_keyring)
393 __key_link_end(dest_keyring, type, prealloc);
394 mutex_unlock(&user->cons_lock);
395 *_key = key;
396 kleave(" = 0 [%d]", key_serial(key));
397 return 0;
399 /* the key is now present - we tell the caller that we found it by
400 * returning -EINPROGRESS */
401 key_already_present:
402 key_put(key);
403 mutex_unlock(&key_construction_mutex);
404 key = key_ref_to_ptr(key_ref);
405 if (dest_keyring) {
406 ret = __key_link_check_live_key(dest_keyring, key);
407 if (ret == 0)
408 __key_link(dest_keyring, key, &prealloc);
409 __key_link_end(dest_keyring, type, prealloc);
410 if (ret < 0)
411 goto link_check_failed;
413 mutex_unlock(&user->cons_lock);
414 *_key = key;
415 kleave(" = -EINPROGRESS [%d]", key_serial(key));
416 return -EINPROGRESS;
418 link_check_failed:
419 mutex_unlock(&user->cons_lock);
420 key_put(key);
421 kleave(" = %d [linkcheck]", ret);
422 return ret;
424 link_prealloc_failed:
425 mutex_unlock(&user->cons_lock);
426 kleave(" = %d [prelink]", ret);
427 return ret;
429 alloc_failed:
430 mutex_unlock(&user->cons_lock);
431 kleave(" = %ld", PTR_ERR(key));
432 return PTR_ERR(key);
436 * Commence key construction.
438 static struct key *construct_key_and_link(struct key_type *type,
439 const char *description,
440 const char *callout_info,
441 size_t callout_len,
442 void *aux,
443 struct key *dest_keyring,
444 unsigned long flags)
446 struct key_user *user;
447 struct key *key;
448 int ret;
450 kenter("");
452 user = key_user_lookup(current_fsuid(), current_user_ns());
453 if (!user)
454 return ERR_PTR(-ENOMEM);
456 construct_get_dest_keyring(&dest_keyring);
458 ret = construct_alloc_key(type, description, dest_keyring, flags, user,
459 &key);
460 key_user_put(user);
462 if (ret == 0) {
463 ret = construct_key(key, callout_info, callout_len, aux,
464 dest_keyring);
465 if (ret < 0) {
466 kdebug("cons failed");
467 goto construction_failed;
469 } else if (ret == -EINPROGRESS) {
470 ret = 0;
471 } else {
472 goto couldnt_alloc_key;
475 key_put(dest_keyring);
476 kleave(" = key %d", key_serial(key));
477 return key;
479 construction_failed:
480 key_negate_and_link(key, key_negative_timeout, NULL, NULL);
481 key_put(key);
482 couldnt_alloc_key:
483 key_put(dest_keyring);
484 kleave(" = %d", ret);
485 return ERR_PTR(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,
518 size_t callout_len,
519 void *aux,
520 struct key *dest_keyring,
521 unsigned long flags)
523 const struct cred *cred = current_cred();
524 struct key *key;
525 key_ref_t key_ref;
526 int ret;
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);
537 if (dest_keyring) {
538 construct_get_dest_keyring(&dest_keyring);
539 ret = key_link(dest_keyring, key);
540 key_put(dest_keyring);
541 if (ret < 0) {
542 key_put(key);
543 key = ERR_PTR(ret);
544 goto error;
547 } else if (PTR_ERR(key_ref) != -EAGAIN) {
548 key = ERR_CAST(key_ref);
549 } else {
550 /* the search failed, but the keyrings were searchable, so we
551 * should consult userspace if we can */
552 key = ERR_PTR(-ENOKEY);
553 if (!callout_info)
554 goto error;
556 key = construct_key_and_link(type, description, callout_info,
557 callout_len, aux, dest_keyring,
558 flags);
561 error:
562 kleave(" = %p", key);
563 return 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)
579 int ret;
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);
584 if (ret < 0)
585 return ret;
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
601 * be passed.
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)
610 struct key *key;
611 size_t callout_len = 0;
612 int ret;
614 if (callout_info)
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);
618 if (!IS_ERR(key)) {
619 ret = wait_for_key_construction(key, false);
620 if (ret < 0) {
621 key_put(key);
622 return ERR_PTR(ret);
625 return key;
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,
646 size_t callout_len,
647 void *aux)
649 struct key *key;
650 int ret;
652 key = request_key_and_link(type, description, callout_info, callout_len,
653 aux, NULL, KEY_ALLOC_IN_QUOTA);
654 if (!IS_ERR(key)) {
655 ret = wait_for_key_construction(key, false);
656 if (ret < 0) {
657 key_put(key);
658 return ERR_PTR(ret);
661 return key;
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,
682 size_t callout_len)
684 return request_key_and_link(type, description, callout_info,
685 callout_len, NULL, NULL,
686 KEY_ALLOC_IN_QUOTA);
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,
707 size_t callout_len,
708 void *aux)
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);