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/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 * call to complete the construction of a key
45 void complete_request_key(struct key_construction *cons, int error)
47 kenter("{%d,%d},%d", cons->key->serial, cons->authkey->serial, error);
50 key_negate_and_link(cons->key, key_negative_timeout, NULL,
53 key_revoke(cons->authkey);
56 key_put(cons->authkey);
59 EXPORT_SYMBOL(complete_request_key);
61 static int umh_keys_init(struct subprocess_info *info)
63 struct cred *cred = (struct cred*)current_cred();
64 struct key *keyring = info->data;
66 * This is called in context of freshly forked kthread before
67 * kernel_execve(), we can just change our ->session_keyring.
69 return install_session_keyring_to_cred(cred, keyring);
72 static void umh_keys_cleanup(struct subprocess_info *info)
74 struct key *keyring = info->data;
78 static int call_usermodehelper_keys(char *path, char **argv, char **envp,
79 struct key *session_keyring, enum umh_wait wait)
81 gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
82 struct subprocess_info *info =
83 call_usermodehelper_setup(path, argv, envp, gfp_mask);
88 call_usermodehelper_setfns(info, umh_keys_init, umh_keys_cleanup,
89 key_get(session_keyring));
90 return call_usermodehelper_exec(info, wait);
94 * request userspace finish the construction of a key
95 * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
97 static int call_sbin_request_key(struct key_construction *cons,
101 const struct cred *cred = current_cred();
102 key_serial_t prkey, sskey;
103 struct key *key = cons->key, *authkey = cons->authkey, *keyring,
105 char *argv[9], *envp[3], uid_str[12], gid_str[12];
106 char key_str[12], keyring_str[3][12];
110 kenter("{%d},{%d},%s", key->serial, authkey->serial, op);
112 ret = install_user_keyrings();
116 /* allocate a new session keyring */
117 sprintf(desc, "_req.%u", key->serial);
119 cred = get_current_cred();
120 keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred,
121 KEY_ALLOC_QUOTA_OVERRUN, NULL);
123 if (IS_ERR(keyring)) {
124 ret = PTR_ERR(keyring);
128 /* attach the auth key to the session keyring */
129 ret = key_link(keyring, authkey);
133 /* record the UID and GID */
134 sprintf(uid_str, "%d", cred->fsuid);
135 sprintf(gid_str, "%d", cred->fsgid);
137 /* we say which key is under construction */
138 sprintf(key_str, "%d", key->serial);
140 /* we specify the process's default keyrings */
141 sprintf(keyring_str[0], "%d",
142 cred->thread_keyring ? cred->thread_keyring->serial : 0);
145 if (cred->tgcred->process_keyring)
146 prkey = cred->tgcred->process_keyring->serial;
147 sprintf(keyring_str[1], "%d", prkey);
150 session = rcu_dereference(cred->tgcred->session_keyring);
152 session = cred->user->session_keyring;
153 sskey = session->serial;
156 sprintf(keyring_str[2], "%d", sskey);
158 /* set up a minimal environment */
160 envp[i++] = "HOME=/";
161 envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
164 /* set up the argument list */
166 argv[i++] = "/sbin/request-key";
167 argv[i++] = (char *) op;
171 argv[i++] = keyring_str[0];
172 argv[i++] = keyring_str[1];
173 argv[i++] = keyring_str[2];
177 ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
179 kdebug("usermode -> 0x%x", ret);
181 /* ret is the exit/wait code */
182 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
183 key_validate(key) < 0)
186 /* ignore any errors from userspace if the key was
195 complete_request_key(cons, ret);
196 kleave(" = %d", ret);
201 * call out to userspace for key construction
202 * - we ignore program failure and go on key status instead
204 static int construct_key(struct key *key, const void *callout_info,
205 size_t callout_len, void *aux,
206 struct key *dest_keyring)
208 struct key_construction *cons;
209 request_key_actor_t actor;
213 kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
215 cons = kmalloc(sizeof(*cons), GFP_KERNEL);
219 /* allocate an authorisation key */
220 authkey = request_key_auth_new(key, callout_info, callout_len,
222 if (IS_ERR(authkey)) {
224 ret = PTR_ERR(authkey);
227 cons->authkey = key_get(authkey);
228 cons->key = key_get(key);
231 actor = call_sbin_request_key;
232 if (key->type->request_key)
233 actor = key->type->request_key;
235 ret = actor(cons, "create", aux);
237 /* check that the actor called complete_request_key() prior to
238 * returning an error */
240 !test_bit(KEY_FLAG_REVOKED, &authkey->flags));
244 kleave(" = %d", ret);
249 * get the appropriate destination keyring for the request
250 * - we return whatever keyring we select with an extra reference upon it which
251 * the caller must release
253 static void construct_get_dest_keyring(struct key **_dest_keyring)
255 struct request_key_auth *rka;
256 const struct cred *cred = current_cred();
257 struct key *dest_keyring = *_dest_keyring, *authkey;
259 kenter("%p", dest_keyring);
261 /* find the appropriate keyring */
263 /* the caller supplied one */
264 key_get(dest_keyring);
266 /* use a default keyring; falling through the cases until we
267 * find one that we actually have */
268 switch (cred->jit_keyring) {
269 case KEY_REQKEY_DEFL_DEFAULT:
270 case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
271 if (cred->request_key_auth) {
272 authkey = cred->request_key_auth;
273 down_read(&authkey->sem);
274 rka = authkey->payload.data;
275 if (!test_bit(KEY_FLAG_REVOKED,
278 key_get(rka->dest_keyring);
279 up_read(&authkey->sem);
284 case KEY_REQKEY_DEFL_THREAD_KEYRING:
285 dest_keyring = key_get(cred->thread_keyring);
289 case KEY_REQKEY_DEFL_PROCESS_KEYRING:
290 dest_keyring = key_get(cred->tgcred->process_keyring);
294 case KEY_REQKEY_DEFL_SESSION_KEYRING:
296 dest_keyring = key_get(
297 rcu_dereference(cred->tgcred->session_keyring));
303 case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
305 key_get(cred->user->session_keyring);
308 case KEY_REQKEY_DEFL_USER_KEYRING:
309 dest_keyring = key_get(cred->user->uid_keyring);
312 case KEY_REQKEY_DEFL_GROUP_KEYRING:
318 *_dest_keyring = dest_keyring;
319 kleave(" [dk %d]", key_serial(dest_keyring));
324 * allocate a new key in under-construction state and attempt to link it in to
325 * the requested place
326 * - may return a key that's already under construction instead
328 static int construct_alloc_key(struct key_type *type,
329 const char *description,
330 struct key *dest_keyring,
332 struct key_user *user,
335 struct keyring_list *prealloc;
336 const struct cred *cred = current_cred();
341 kenter("%s,%s,,,", type->name, description);
344 mutex_lock(&user->cons_lock);
346 key = key_alloc(type, description, cred->fsuid, cred->fsgid, cred,
351 set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
354 ret = __key_link_begin(dest_keyring, type, description,
357 goto link_prealloc_failed;
360 /* attach the key to the destination keyring under lock, but we do need
361 * to do another check just in case someone beat us to it whilst we
362 * waited for locks */
363 mutex_lock(&key_construction_mutex);
365 key_ref = search_process_keyrings(type, description, type->match, cred);
366 if (!IS_ERR(key_ref))
367 goto key_already_present;
370 __key_link(dest_keyring, key, &prealloc);
372 mutex_unlock(&key_construction_mutex);
374 __key_link_end(dest_keyring, type, prealloc);
375 mutex_unlock(&user->cons_lock);
377 kleave(" = 0 [%d]", key_serial(key));
380 /* the key is now present - we tell the caller that we found it by
381 * returning -EINPROGRESS */
384 mutex_unlock(&key_construction_mutex);
385 key = key_ref_to_ptr(key_ref);
387 ret = __key_link_check_live_key(dest_keyring, key);
389 __key_link(dest_keyring, key, &prealloc);
390 __key_link_end(dest_keyring, type, prealloc);
392 goto link_check_failed;
394 mutex_unlock(&user->cons_lock);
396 kleave(" = -EINPROGRESS [%d]", key_serial(key));
400 mutex_unlock(&user->cons_lock);
402 kleave(" = %d [linkcheck]", ret);
405 link_prealloc_failed:
406 mutex_unlock(&user->cons_lock);
407 kleave(" = %d [prelink]", ret);
411 mutex_unlock(&user->cons_lock);
412 kleave(" = %ld", PTR_ERR(key));
417 * commence key construction
419 static struct key *construct_key_and_link(struct key_type *type,
420 const char *description,
421 const char *callout_info,
424 struct key *dest_keyring,
427 struct key_user *user;
433 user = key_user_lookup(current_fsuid(), current_user_ns());
435 return ERR_PTR(-ENOMEM);
437 construct_get_dest_keyring(&dest_keyring);
439 ret = construct_alloc_key(type, description, dest_keyring, flags, user,
444 ret = construct_key(key, callout_info, callout_len, aux,
447 kdebug("cons failed");
448 goto construction_failed;
450 } else if (ret == -EINPROGRESS) {
456 key_put(dest_keyring);
457 kleave(" = key %d", key_serial(key));
461 key_negate_and_link(key, key_negative_timeout, NULL, NULL);
463 key_put(dest_keyring);
464 kleave(" = %d", ret);
470 * - search the process's keyrings
471 * - check the list of keys being created or updated
472 * - call out to userspace for a key if supplementary info was provided
473 * - cache the key in an appropriate keyring
475 struct key *request_key_and_link(struct key_type *type,
476 const char *description,
477 const void *callout_info,
480 struct key *dest_keyring,
483 const struct cred *cred = current_cred();
488 kenter("%s,%s,%p,%zu,%p,%p,%lx",
489 type->name, description, callout_info, callout_len, aux,
490 dest_keyring, flags);
492 /* search all the process keyrings for a key */
493 key_ref = search_process_keyrings(type, description, type->match,
496 if (!IS_ERR(key_ref)) {
497 key = key_ref_to_ptr(key_ref);
499 construct_get_dest_keyring(&dest_keyring);
500 ret = key_link(dest_keyring, key);
501 key_put(dest_keyring);
508 } else if (PTR_ERR(key_ref) != -EAGAIN) {
509 key = ERR_CAST(key_ref);
511 /* the search failed, but the keyrings were searchable, so we
512 * should consult userspace if we can */
513 key = ERR_PTR(-ENOKEY);
517 key = construct_key_and_link(type, description, callout_info,
518 callout_len, aux, dest_keyring,
523 kleave(" = %p", key);
528 * wait for construction of a key to complete
530 int wait_for_key_construction(struct key *key, bool intr)
534 ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
535 intr ? key_wait_bit_intr : key_wait_bit,
536 intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
539 if (test_bit(KEY_FLAG_NEGATIVE, &key->flags))
541 return key_validate(key);
543 EXPORT_SYMBOL(wait_for_key_construction);
547 * - search the process's keyrings
548 * - check the list of keys being created or updated
549 * - call out to userspace for a key if supplementary info was provided
550 * - waits uninterruptible for creation to complete
552 struct key *request_key(struct key_type *type,
553 const char *description,
554 const char *callout_info)
557 size_t callout_len = 0;
561 callout_len = strlen(callout_info);
562 key = request_key_and_link(type, description, callout_info, callout_len,
563 NULL, NULL, KEY_ALLOC_IN_QUOTA);
565 ret = wait_for_key_construction(key, false);
573 EXPORT_SYMBOL(request_key);
576 * request a key with auxiliary data for the upcaller
577 * - search the process's keyrings
578 * - check the list of keys being created or updated
579 * - call out to userspace for a key if supplementary info was provided
580 * - waits uninterruptible for creation to complete
582 struct key *request_key_with_auxdata(struct key_type *type,
583 const char *description,
584 const void *callout_info,
591 key = request_key_and_link(type, description, callout_info, callout_len,
592 aux, NULL, KEY_ALLOC_IN_QUOTA);
594 ret = wait_for_key_construction(key, false);
602 EXPORT_SYMBOL(request_key_with_auxdata);
605 * request a key (allow async construction)
606 * - search the process's keyrings
607 * - check the list of keys being created or updated
608 * - call out to userspace for a key if supplementary info was provided
610 struct key *request_key_async(struct key_type *type,
611 const char *description,
612 const void *callout_info,
615 return request_key_and_link(type, description, callout_info,
616 callout_len, NULL, NULL,
619 EXPORT_SYMBOL(request_key_async);
622 * request a key with auxiliary data for the upcaller (allow async construction)
623 * - search the process's keyrings
624 * - check the list of keys being created or updated
625 * - call out to userspace for a key if supplementary info was provided
627 struct key *request_key_async_with_auxdata(struct key_type *type,
628 const char *description,
629 const void *callout_info,
633 return request_key_and_link(type, description, callout_info,
634 callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA);
636 EXPORT_SYMBOL(request_key_async_with_auxdata);