1 /* Management of a process's keyrings
3 * Copyright (C) 2004-2005, 2008 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.
12 #include <linux/module.h>
13 #include <linux/init.h>
14 #include <linux/sched.h>
15 #include <linux/slab.h>
16 #include <linux/keyctl.h>
18 #include <linux/err.h>
19 #include <linux/mutex.h>
20 #include <asm/uaccess.h>
23 /* session keyring create vs join semaphore */
24 static DEFINE_MUTEX(key_session_mutex);
26 /* user keyring creation semaphore */
27 static DEFINE_MUTEX(key_user_keyring_mutex);
29 /* the root user's tracking struct */
30 struct key_user root_key_user = {
31 .usage = ATOMIC_INIT(3),
32 .cons_lock = __MUTEX_INITIALIZER(root_key_user.cons_lock),
33 .lock = __SPIN_LOCK_UNLOCKED(root_key_user.lock),
34 .nkeys = ATOMIC_INIT(2),
35 .nikeys = ATOMIC_INIT(2),
39 /*****************************************************************************/
41 * install user and user session keyrings for a particular UID
43 int install_user_keyrings(void)
45 struct user_struct *user = current->user;
46 struct key *uid_keyring, *session_keyring;
50 kenter("%p{%u}", user, user->uid);
52 if (user->uid_keyring) {
53 kleave(" = 0 [exist]");
57 mutex_lock(&key_user_keyring_mutex);
60 if (!user->uid_keyring) {
61 /* get the UID-specific keyring
62 * - there may be one in existence already as it may have been
63 * pinned by a session, but the user_struct pointing to it
64 * may have been destroyed by setuid */
65 sprintf(buf, "_uid.%u", user->uid);
67 uid_keyring = find_keyring_by_name(buf, true);
68 if (IS_ERR(uid_keyring)) {
69 uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1,
70 current, KEY_ALLOC_IN_QUOTA,
72 if (IS_ERR(uid_keyring)) {
73 ret = PTR_ERR(uid_keyring);
78 /* get a default session keyring (which might also exist
80 sprintf(buf, "_uid_ses.%u", user->uid);
82 session_keyring = find_keyring_by_name(buf, true);
83 if (IS_ERR(session_keyring)) {
85 keyring_alloc(buf, user->uid, (gid_t) -1,
86 current, KEY_ALLOC_IN_QUOTA,
88 if (IS_ERR(session_keyring)) {
89 ret = PTR_ERR(session_keyring);
93 /* we install a link from the user session keyring to
95 ret = key_link(session_keyring, uid_keyring);
97 goto error_release_both;
100 /* install the keyrings */
101 user->uid_keyring = uid_keyring;
102 user->session_keyring = session_keyring;
105 mutex_unlock(&key_user_keyring_mutex);
110 key_put(session_keyring);
112 key_put(uid_keyring);
114 mutex_unlock(&key_user_keyring_mutex);
115 kleave(" = %d", ret);
119 /*****************************************************************************/
121 * deal with the UID changing
123 void switch_uid_keyring(struct user_struct *new_user)
125 #if 0 /* do nothing for now */
128 /* switch to the new user's session keyring if we were running under
129 * root's default session keyring */
130 if (new_user->uid != 0 &&
131 current->session_keyring == &root_session_keyring
133 atomic_inc(&new_user->session_keyring->usage);
136 old = current->session_keyring;
137 current->session_keyring = new_user->session_keyring;
138 task_unlock(current);
144 } /* end switch_uid_keyring() */
146 /*****************************************************************************/
148 * install a fresh thread keyring, discarding the old one
150 int install_thread_keyring(void)
152 struct task_struct *tsk = current;
153 struct key *keyring, *old;
157 sprintf(buf, "_tid.%u", tsk->pid);
159 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
160 KEY_ALLOC_QUOTA_OVERRUN, NULL);
161 if (IS_ERR(keyring)) {
162 ret = PTR_ERR(keyring);
167 old = tsk->thread_keyring;
168 tsk->thread_keyring = keyring;
177 } /* end install_thread_keyring() */
179 /*****************************************************************************/
181 * make sure a process keyring is installed
183 int install_process_keyring(void)
185 struct task_struct *tsk = current;
192 if (!tsk->signal->process_keyring) {
193 sprintf(buf, "_pid.%u", tsk->tgid);
195 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
196 KEY_ALLOC_QUOTA_OVERRUN, NULL);
197 if (IS_ERR(keyring)) {
198 ret = PTR_ERR(keyring);
203 spin_lock_irq(&tsk->sighand->siglock);
204 if (!tsk->signal->process_keyring) {
205 tsk->signal->process_keyring = keyring;
208 spin_unlock_irq(&tsk->sighand->siglock);
217 } /* end install_process_keyring() */
219 /*****************************************************************************/
221 * install a session keyring, discarding the old one
222 * - if a keyring is not supplied, an empty one is invented
224 static int install_session_keyring(struct key *keyring)
226 struct task_struct *tsk = current;
233 /* create an empty session keyring */
235 sprintf(buf, "_ses.%u", tsk->tgid);
237 flags = KEY_ALLOC_QUOTA_OVERRUN;
238 if (tsk->signal->session_keyring)
239 flags = KEY_ALLOC_IN_QUOTA;
241 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, tsk,
244 return PTR_ERR(keyring);
247 atomic_inc(&keyring->usage);
250 /* install the keyring */
251 spin_lock_irq(&tsk->sighand->siglock);
252 old = tsk->signal->session_keyring;
253 rcu_assign_pointer(tsk->signal->session_keyring, keyring);
254 spin_unlock_irq(&tsk->sighand->siglock);
256 /* we're using RCU on the pointer, but there's no point synchronising
257 * on it if it didn't previously point to anything */
265 } /* end install_session_keyring() */
267 /*****************************************************************************/
269 * copy the keys in a thread group for fork without CLONE_THREAD
271 int copy_thread_group_keys(struct task_struct *tsk)
273 key_check(current->thread_group->session_keyring);
274 key_check(current->thread_group->process_keyring);
276 /* no process keyring yet */
277 tsk->signal->process_keyring = NULL;
279 /* same session keyring */
281 tsk->signal->session_keyring =
282 key_get(rcu_dereference(current->signal->session_keyring));
287 } /* end copy_thread_group_keys() */
289 /*****************************************************************************/
291 * copy the keys for fork
293 int copy_keys(unsigned long clone_flags, struct task_struct *tsk)
295 key_check(tsk->thread_keyring);
296 key_check(tsk->request_key_auth);
298 /* no thread keyring yet */
299 tsk->thread_keyring = NULL;
301 /* copy the request_key() authorisation for this thread */
302 key_get(tsk->request_key_auth);
306 } /* end copy_keys() */
308 /*****************************************************************************/
310 * dispose of thread group keys upon thread group destruction
312 void exit_thread_group_keys(struct signal_struct *tg)
314 key_put(tg->session_keyring);
315 key_put(tg->process_keyring);
317 } /* end exit_thread_group_keys() */
319 /*****************************************************************************/
321 * dispose of per-thread keys upon thread exit
323 void exit_keys(struct task_struct *tsk)
325 key_put(tsk->thread_keyring);
326 key_put(tsk->request_key_auth);
328 } /* end exit_keys() */
330 /*****************************************************************************/
334 int exec_keys(struct task_struct *tsk)
338 /* newly exec'd tasks don't get a thread keyring */
340 old = tsk->thread_keyring;
341 tsk->thread_keyring = NULL;
346 /* discard the process keyring from a newly exec'd task */
347 spin_lock_irq(&tsk->sighand->siglock);
348 old = tsk->signal->process_keyring;
349 tsk->signal->process_keyring = NULL;
350 spin_unlock_irq(&tsk->sighand->siglock);
356 } /* end exec_keys() */
358 /*****************************************************************************/
360 * deal with SUID programs
361 * - we might want to make this invent a new session keyring
363 int suid_keys(struct task_struct *tsk)
367 } /* end suid_keys() */
369 /*****************************************************************************/
371 * the filesystem user ID changed
373 void key_fsuid_changed(struct task_struct *tsk)
375 /* update the ownership of the thread keyring */
376 if (tsk->thread_keyring) {
377 down_write(&tsk->thread_keyring->sem);
378 tsk->thread_keyring->uid = tsk->fsuid;
379 up_write(&tsk->thread_keyring->sem);
382 } /* end key_fsuid_changed() */
384 /*****************************************************************************/
386 * the filesystem group ID changed
388 void key_fsgid_changed(struct task_struct *tsk)
390 /* update the ownership of the thread keyring */
391 if (tsk->thread_keyring) {
392 down_write(&tsk->thread_keyring->sem);
393 tsk->thread_keyring->gid = tsk->fsgid;
394 up_write(&tsk->thread_keyring->sem);
397 } /* end key_fsgid_changed() */
399 /*****************************************************************************/
401 * search the process keyrings for the first matching key
402 * - we use the supplied match function to see if the description (or other
403 * feature of interest) matches
404 * - we return -EAGAIN if we didn't find any matching key
405 * - we return -ENOKEY if we found only negative matching keys
407 key_ref_t search_process_keyrings(struct key_type *type,
408 const void *description,
409 key_match_func_t match,
410 struct task_struct *context)
412 struct request_key_auth *rka;
413 key_ref_t key_ref, ret, err;
417 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
418 * searchable, but we failed to find a key or we found a negative key;
419 * otherwise we want to return a sample error (probably -EACCES) if
420 * none of the keyrings were searchable
422 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
426 err = ERR_PTR(-EAGAIN);
428 /* search the thread keyring first */
429 if (context->thread_keyring) {
430 key_ref = keyring_search_aux(
431 make_key_ref(context->thread_keyring, 1),
432 context, type, description, match);
433 if (!IS_ERR(key_ref))
436 switch (PTR_ERR(key_ref)) {
437 case -EAGAIN: /* no key */
440 case -ENOKEY: /* negative key */
449 /* search the process keyring second */
450 if (context->signal->process_keyring) {
451 key_ref = keyring_search_aux(
452 make_key_ref(context->signal->process_keyring, 1),
453 context, type, description, match);
454 if (!IS_ERR(key_ref))
457 switch (PTR_ERR(key_ref)) {
458 case -EAGAIN: /* no key */
461 case -ENOKEY: /* negative key */
470 /* search the session keyring */
471 if (context->signal->session_keyring) {
473 key_ref = keyring_search_aux(
474 make_key_ref(rcu_dereference(
475 context->signal->session_keyring),
477 context, type, description, match);
480 if (!IS_ERR(key_ref))
483 switch (PTR_ERR(key_ref)) {
484 case -EAGAIN: /* no key */
487 case -ENOKEY: /* negative key */
495 /* or search the user-session keyring */
496 else if (context->user->session_keyring) {
497 key_ref = keyring_search_aux(
498 make_key_ref(context->user->session_keyring, 1),
499 context, type, description, match);
500 if (!IS_ERR(key_ref))
503 switch (PTR_ERR(key_ref)) {
504 case -EAGAIN: /* no key */
507 case -ENOKEY: /* negative key */
516 /* if this process has an instantiation authorisation key, then we also
517 * search the keyrings of the process mentioned there
518 * - we don't permit access to request_key auth keys via this method
520 if (context->request_key_auth &&
521 context == current &&
522 type != &key_type_request_key_auth
524 /* defend against the auth key being revoked */
525 down_read(&context->request_key_auth->sem);
527 if (key_validate(context->request_key_auth) == 0) {
528 rka = context->request_key_auth->payload.data;
530 key_ref = search_process_keyrings(type, description,
531 match, rka->context);
533 up_read(&context->request_key_auth->sem);
535 if (!IS_ERR(key_ref))
538 switch (PTR_ERR(key_ref)) {
539 case -EAGAIN: /* no key */
542 case -ENOKEY: /* negative key */
550 up_read(&context->request_key_auth->sem);
554 /* no key - decide on the error we're going to go for */
555 key_ref = ret ? ret : err;
560 } /* end search_process_keyrings() */
562 /*****************************************************************************/
564 * see if the key we're looking at is the target key
566 static int lookup_user_key_possessed(const struct key *key, const void *target)
568 return key == target;
570 } /* end lookup_user_key_possessed() */
572 /*****************************************************************************/
574 * lookup a key given a key ID from userspace with a given permissions mask
575 * - don't create special keyrings unless so requested
576 * - partially constructed keys aren't found unless requested
578 key_ref_t lookup_user_key(key_serial_t id, int create, int partial,
581 struct request_key_auth *rka;
582 struct task_struct *t = current;
583 key_ref_t key_ref, skey_ref;
587 key_ref = ERR_PTR(-ENOKEY);
590 case KEY_SPEC_THREAD_KEYRING:
591 if (!t->thread_keyring) {
595 ret = install_thread_keyring();
602 key = t->thread_keyring;
603 atomic_inc(&key->usage);
604 key_ref = make_key_ref(key, 1);
607 case KEY_SPEC_PROCESS_KEYRING:
608 if (!t->signal->process_keyring) {
612 ret = install_process_keyring();
619 key = t->signal->process_keyring;
620 atomic_inc(&key->usage);
621 key_ref = make_key_ref(key, 1);
624 case KEY_SPEC_SESSION_KEYRING:
625 if (!t->signal->session_keyring) {
626 /* always install a session keyring upon access if one
627 * doesn't exist yet */
628 ret = install_user_keyrings();
631 ret = install_session_keyring(t->user->session_keyring);
637 key = rcu_dereference(t->signal->session_keyring);
638 atomic_inc(&key->usage);
640 key_ref = make_key_ref(key, 1);
643 case KEY_SPEC_USER_KEYRING:
644 if (!t->user->uid_keyring) {
645 ret = install_user_keyrings();
650 key = t->user->uid_keyring;
651 atomic_inc(&key->usage);
652 key_ref = make_key_ref(key, 1);
655 case KEY_SPEC_USER_SESSION_KEYRING:
656 if (!t->user->session_keyring) {
657 ret = install_user_keyrings();
662 key = t->user->session_keyring;
663 atomic_inc(&key->usage);
664 key_ref = make_key_ref(key, 1);
667 case KEY_SPEC_GROUP_KEYRING:
668 /* group keyrings are not yet supported */
669 key = ERR_PTR(-EINVAL);
672 case KEY_SPEC_REQKEY_AUTH_KEY:
673 key = t->request_key_auth;
677 atomic_inc(&key->usage);
678 key_ref = make_key_ref(key, 1);
681 case KEY_SPEC_REQUESTOR_KEYRING:
682 if (!t->request_key_auth)
685 down_read(&t->request_key_auth->sem);
686 if (t->request_key_auth->flags & KEY_FLAG_REVOKED) {
687 key_ref = ERR_PTR(-EKEYREVOKED);
690 rka = t->request_key_auth->payload.data;
691 key = rka->dest_keyring;
692 atomic_inc(&key->usage);
694 up_read(&t->request_key_auth->sem);
697 key_ref = make_key_ref(key, 1);
701 key_ref = ERR_PTR(-EINVAL);
705 key = key_lookup(id);
707 key_ref = ERR_CAST(key);
711 key_ref = make_key_ref(key, 0);
713 /* check to see if we possess the key */
714 skey_ref = search_process_keyrings(key->type, key,
715 lookup_user_key_possessed,
718 if (!IS_ERR(skey_ref)) {
727 ret = wait_for_key_construction(key, true);
738 ret = key_validate(key);
744 if (!partial && !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
747 /* check the permissions */
748 ret = key_task_permission(key_ref, t, perm);
756 key_ref_put(key_ref);
757 key_ref = ERR_PTR(ret);
760 } /* end lookup_user_key() */
762 /*****************************************************************************/
764 * join the named keyring as the session keyring if possible, or attempt to
765 * create a new one of that name if not
766 * - if the name is NULL, an empty anonymous keyring is installed instead
767 * - named session keyring joining is done with a semaphore held
769 long join_session_keyring(const char *name)
771 struct task_struct *tsk = current;
775 /* if no name is provided, install an anonymous keyring */
777 ret = install_session_keyring(NULL);
782 ret = rcu_dereference(tsk->signal->session_keyring)->serial;
787 /* allow the user to join or create a named keyring */
788 mutex_lock(&key_session_mutex);
790 /* look for an existing keyring of this name */
791 keyring = find_keyring_by_name(name, false);
792 if (PTR_ERR(keyring) == -ENOKEY) {
793 /* not found - try and create a new one */
794 keyring = keyring_alloc(name, tsk->uid, tsk->gid, tsk,
795 KEY_ALLOC_IN_QUOTA, NULL);
796 if (IS_ERR(keyring)) {
797 ret = PTR_ERR(keyring);
801 else if (IS_ERR(keyring)) {
802 ret = PTR_ERR(keyring);
806 /* we've got a keyring - now to install it */
807 ret = install_session_keyring(keyring);
811 ret = keyring->serial;
815 mutex_unlock(&key_session_mutex);
819 } /* end join_session_keyring() */