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);
62 * request userspace finish the construction of a key
63 * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
65 static int call_sbin_request_key(struct key_construction *cons,
69 struct task_struct *tsk = current;
70 const struct cred *cred = current_cred();
71 key_serial_t prkey, sskey;
72 struct key *key = cons->key, *authkey = cons->authkey, *keyring;
73 char *argv[9], *envp[3], uid_str[12], gid_str[12];
74 char key_str[12], keyring_str[3][12];
78 kenter("{%d},{%d},%s", key->serial, authkey->serial, op);
80 ret = install_user_keyrings();
84 /* allocate a new session keyring */
85 sprintf(desc, "_req.%u", key->serial);
87 keyring = keyring_alloc(desc, current_fsuid(), current_fsgid(), current,
88 KEY_ALLOC_QUOTA_OVERRUN, NULL);
89 if (IS_ERR(keyring)) {
90 ret = PTR_ERR(keyring);
94 /* attach the auth key to the session keyring */
95 ret = __key_link(keyring, authkey);
99 /* record the UID and GID */
100 sprintf(uid_str, "%d", cred->fsuid);
101 sprintf(gid_str, "%d", cred->fsgid);
103 /* we say which key is under construction */
104 sprintf(key_str, "%d", key->serial);
106 /* we specify the process's default keyrings */
107 sprintf(keyring_str[0], "%d",
108 cred->thread_keyring ?
109 cred->thread_keyring->serial : 0);
112 if (tsk->signal->process_keyring)
113 prkey = tsk->signal->process_keyring->serial;
115 sprintf(keyring_str[1], "%d", prkey);
117 if (tsk->signal->session_keyring) {
119 sskey = rcu_dereference(tsk->signal->session_keyring)->serial;
122 sskey = cred->user->session_keyring->serial;
125 sprintf(keyring_str[2], "%d", sskey);
127 /* set up a minimal environment */
129 envp[i++] = "HOME=/";
130 envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
133 /* set up the argument list */
135 argv[i++] = "/sbin/request-key";
136 argv[i++] = (char *) op;
140 argv[i++] = keyring_str[0];
141 argv[i++] = keyring_str[1];
142 argv[i++] = keyring_str[2];
146 ret = call_usermodehelper_keys(argv[0], argv, envp, keyring,
148 kdebug("usermode -> 0x%x", ret);
150 /* ret is the exit/wait code */
151 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
152 key_validate(key) < 0)
155 /* ignore any errors from userspace if the key was
164 kleave(" = %d", ret);
165 complete_request_key(cons, ret);
170 * call out to userspace for key construction
171 * - we ignore program failure and go on key status instead
173 static int construct_key(struct key *key, const void *callout_info,
174 size_t callout_len, void *aux,
175 struct key *dest_keyring)
177 struct key_construction *cons;
178 request_key_actor_t actor;
182 kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
184 cons = kmalloc(sizeof(*cons), GFP_KERNEL);
188 /* allocate an authorisation key */
189 authkey = request_key_auth_new(key, callout_info, callout_len,
191 if (IS_ERR(authkey)) {
193 ret = PTR_ERR(authkey);
196 cons->authkey = key_get(authkey);
197 cons->key = key_get(key);
200 actor = call_sbin_request_key;
201 if (key->type->request_key)
202 actor = key->type->request_key;
204 ret = actor(cons, "create", aux);
206 /* check that the actor called complete_request_key() prior to
207 * returning an error */
209 !test_bit(KEY_FLAG_REVOKED, &authkey->flags));
213 kleave(" = %d", ret);
218 * get the appropriate destination keyring for the request
219 * - we return whatever keyring we select with an extra reference upon it which
220 * the caller must release
222 static void construct_get_dest_keyring(struct key **_dest_keyring)
224 struct request_key_auth *rka;
225 struct task_struct *tsk = current;
226 struct key *dest_keyring = *_dest_keyring, *authkey;
228 kenter("%p", dest_keyring);
230 /* find the appropriate keyring */
232 /* the caller supplied one */
233 key_get(dest_keyring);
235 /* use a default keyring; falling through the cases until we
236 * find one that we actually have */
237 switch (tsk->cred->jit_keyring) {
238 case KEY_REQKEY_DEFL_DEFAULT:
239 case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
240 if (tsk->cred->request_key_auth) {
241 authkey = tsk->cred->request_key_auth;
242 down_read(&authkey->sem);
243 rka = authkey->payload.data;
244 if (!test_bit(KEY_FLAG_REVOKED,
247 key_get(rka->dest_keyring);
248 up_read(&authkey->sem);
253 case KEY_REQKEY_DEFL_THREAD_KEYRING:
254 dest_keyring = key_get(tsk->cred->thread_keyring);
258 case KEY_REQKEY_DEFL_PROCESS_KEYRING:
259 dest_keyring = key_get(tsk->signal->process_keyring);
263 case KEY_REQKEY_DEFL_SESSION_KEYRING:
265 dest_keyring = key_get(
266 rcu_dereference(tsk->signal->session_keyring));
272 case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
274 key_get(tsk->cred->user->session_keyring);
277 case KEY_REQKEY_DEFL_USER_KEYRING:
278 dest_keyring = key_get(tsk->cred->user->uid_keyring);
281 case KEY_REQKEY_DEFL_GROUP_KEYRING:
287 *_dest_keyring = dest_keyring;
288 kleave(" [dk %d]", key_serial(dest_keyring));
293 * allocate a new key in under-construction state and attempt to link it in to
294 * the requested place
295 * - may return a key that's already under construction instead
297 static int construct_alloc_key(struct key_type *type,
298 const char *description,
299 struct key *dest_keyring,
301 struct key_user *user,
307 kenter("%s,%s,,,", type->name, description);
309 mutex_lock(&user->cons_lock);
311 key = key_alloc(type, description,
312 current_fsuid(), current_fsgid(), current, KEY_POS_ALL,
317 set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
319 down_write(&dest_keyring->sem);
321 /* attach the key to the destination keyring under lock, but we do need
322 * to do another check just in case someone beat us to it whilst we
323 * waited for locks */
324 mutex_lock(&key_construction_mutex);
326 key_ref = search_process_keyrings(type, description, type->match,
328 if (!IS_ERR(key_ref))
329 goto key_already_present;
331 __key_link(dest_keyring, key);
333 mutex_unlock(&key_construction_mutex);
334 up_write(&dest_keyring->sem);
335 mutex_unlock(&user->cons_lock);
337 kleave(" = 0 [%d]", key_serial(key));
341 mutex_unlock(&key_construction_mutex);
343 up_write(&dest_keyring->sem);
344 mutex_unlock(&user->cons_lock);
346 *_key = key = key_ref_to_ptr(key_ref);
347 kleave(" = -EINPROGRESS [%d]", key_serial(key));
351 mutex_unlock(&user->cons_lock);
353 kleave(" = %ld", PTR_ERR(key));
358 * commence key construction
360 static struct key *construct_key_and_link(struct key_type *type,
361 const char *description,
362 const char *callout_info,
365 struct key *dest_keyring,
368 struct key_user *user;
372 user = key_user_lookup(current_fsuid());
374 return ERR_PTR(-ENOMEM);
376 construct_get_dest_keyring(&dest_keyring);
378 ret = construct_alloc_key(type, description, dest_keyring, flags, user,
383 ret = construct_key(key, callout_info, callout_len, aux,
386 goto construction_failed;
389 key_put(dest_keyring);
393 key_negate_and_link(key, key_negative_timeout, NULL, NULL);
395 key_put(dest_keyring);
401 * - search the process's keyrings
402 * - check the list of keys being created or updated
403 * - call out to userspace for a key if supplementary info was provided
404 * - cache the key in an appropriate keyring
406 struct key *request_key_and_link(struct key_type *type,
407 const char *description,
408 const void *callout_info,
411 struct key *dest_keyring,
417 kenter("%s,%s,%p,%zu,%p,%p,%lx",
418 type->name, description, callout_info, callout_len, aux,
419 dest_keyring, flags);
421 /* search all the process keyrings for a key */
422 key_ref = search_process_keyrings(type, description, type->match,
425 if (!IS_ERR(key_ref)) {
426 key = key_ref_to_ptr(key_ref);
427 } else if (PTR_ERR(key_ref) != -EAGAIN) {
428 key = ERR_CAST(key_ref);
430 /* the search failed, but the keyrings were searchable, so we
431 * should consult userspace if we can */
432 key = ERR_PTR(-ENOKEY);
436 key = construct_key_and_link(type, description, callout_info,
437 callout_len, aux, dest_keyring,
442 kleave(" = %p", key);
447 * wait for construction of a key to complete
449 int wait_for_key_construction(struct key *key, bool intr)
453 ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
454 intr ? key_wait_bit_intr : key_wait_bit,
455 intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
458 return key_validate(key);
460 EXPORT_SYMBOL(wait_for_key_construction);
464 * - search the process's keyrings
465 * - check the list of keys being created or updated
466 * - call out to userspace for a key if supplementary info was provided
467 * - waits uninterruptible for creation to complete
469 struct key *request_key(struct key_type *type,
470 const char *description,
471 const char *callout_info)
474 size_t callout_len = 0;
478 callout_len = strlen(callout_info);
479 key = request_key_and_link(type, description, callout_info, callout_len,
480 NULL, NULL, KEY_ALLOC_IN_QUOTA);
482 ret = wait_for_key_construction(key, false);
490 EXPORT_SYMBOL(request_key);
493 * request a key with auxiliary data for the upcaller
494 * - search the process's keyrings
495 * - check the list of keys being created or updated
496 * - call out to userspace for a key if supplementary info was provided
497 * - waits uninterruptible for creation to complete
499 struct key *request_key_with_auxdata(struct key_type *type,
500 const char *description,
501 const void *callout_info,
508 key = request_key_and_link(type, description, callout_info, callout_len,
509 aux, NULL, KEY_ALLOC_IN_QUOTA);
511 ret = wait_for_key_construction(key, false);
519 EXPORT_SYMBOL(request_key_with_auxdata);
522 * request a key (allow async construction)
523 * - search the process's keyrings
524 * - check the list of keys being created or updated
525 * - call out to userspace for a key if supplementary info was provided
527 struct key *request_key_async(struct key_type *type,
528 const char *description,
529 const void *callout_info,
532 return request_key_and_link(type, description, callout_info,
533 callout_len, NULL, NULL,
536 EXPORT_SYMBOL(request_key_async);
539 * request a key with auxiliary data for the upcaller (allow async construction)
540 * - search the process's keyrings
541 * - check the list of keys being created or updated
542 * - call out to userspace for a key if supplementary info was provided
544 struct key *request_key_async_with_auxdata(struct key_type *type,
545 const char *description,
546 const void *callout_info,
550 return request_key_and_link(type, description, callout_info,
551 callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA);
553 EXPORT_SYMBOL(request_key_async_with_auxdata);