1 /* process_keys.c: management of a process's keyrings
3 * Copyright (C) 2004-5 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 /* the root user's tracking struct */
27 struct key_user root_key_user = {
28 .usage = ATOMIC_INIT(3),
29 .consq = LIST_HEAD_INIT(root_key_user.consq),
30 .lock = SPIN_LOCK_UNLOCKED,
31 .nkeys = ATOMIC_INIT(2),
32 .nikeys = ATOMIC_INIT(2),
36 /* the root user's UID keyring */
37 struct key root_user_keyring = {
38 .usage = ATOMIC_INIT(1),
40 .type = &key_type_keyring,
41 .user = &root_key_user,
42 .sem = __RWSEM_INITIALIZER(root_user_keyring.sem),
43 .perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
44 .flags = 1 << KEY_FLAG_INSTANTIATED,
45 .description = "_uid.0",
47 .magic = KEY_DEBUG_MAGIC,
51 /* the root user's default session keyring */
52 struct key root_session_keyring = {
53 .usage = ATOMIC_INIT(1),
55 .type = &key_type_keyring,
56 .user = &root_key_user,
57 .sem = __RWSEM_INITIALIZER(root_session_keyring.sem),
58 .perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL,
59 .flags = 1 << KEY_FLAG_INSTANTIATED,
60 .description = "_uid_ses.0",
62 .magic = KEY_DEBUG_MAGIC,
66 /*****************************************************************************/
68 * allocate the keyrings to be associated with a UID
70 int alloc_uid_keyring(struct user_struct *user)
72 struct key *uid_keyring, *session_keyring;
76 /* concoct a default session keyring */
77 sprintf(buf, "_uid_ses.%u", user->uid);
79 session_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, 0, NULL);
80 if (IS_ERR(session_keyring)) {
81 ret = PTR_ERR(session_keyring);
85 /* and a UID specific keyring, pointed to by the default session
87 sprintf(buf, "_uid.%u", user->uid);
89 uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1, 0,
91 if (IS_ERR(uid_keyring)) {
92 key_put(session_keyring);
93 ret = PTR_ERR(uid_keyring);
97 /* install the keyrings */
98 user->uid_keyring = uid_keyring;
99 user->session_keyring = session_keyring;
105 } /* end alloc_uid_keyring() */
107 /*****************************************************************************/
109 * deal with the UID changing
111 void switch_uid_keyring(struct user_struct *new_user)
113 #if 0 /* do nothing for now */
116 /* switch to the new user's session keyring if we were running under
117 * root's default session keyring */
118 if (new_user->uid != 0 &&
119 current->session_keyring == &root_session_keyring
121 atomic_inc(&new_user->session_keyring->usage);
124 old = current->session_keyring;
125 current->session_keyring = new_user->session_keyring;
126 task_unlock(current);
132 } /* end switch_uid_keyring() */
134 /*****************************************************************************/
136 * install a fresh thread keyring, discarding the old one
138 int install_thread_keyring(struct task_struct *tsk)
140 struct key *keyring, *old;
144 sprintf(buf, "_tid.%u", tsk->pid);
146 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
147 if (IS_ERR(keyring)) {
148 ret = PTR_ERR(keyring);
153 old = tsk->thread_keyring;
154 tsk->thread_keyring = keyring;
163 } /* end install_thread_keyring() */
165 /*****************************************************************************/
167 * make sure a process keyring is installed
169 int install_process_keyring(struct task_struct *tsk)
177 if (!tsk->signal->process_keyring) {
178 sprintf(buf, "_pid.%u", tsk->tgid);
180 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
181 if (IS_ERR(keyring)) {
182 ret = PTR_ERR(keyring);
187 spin_lock_irq(&tsk->sighand->siglock);
188 if (!tsk->signal->process_keyring) {
189 tsk->signal->process_keyring = keyring;
192 spin_unlock_irq(&tsk->sighand->siglock);
201 } /* end install_process_keyring() */
203 /*****************************************************************************/
205 * install a session keyring, discarding the old one
206 * - if a keyring is not supplied, an empty one is invented
208 static int install_session_keyring(struct task_struct *tsk,
216 /* create an empty session keyring */
218 sprintf(buf, "_ses.%u", tsk->tgid);
220 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
222 return PTR_ERR(keyring);
225 atomic_inc(&keyring->usage);
228 /* install the keyring */
229 spin_lock_irq(&tsk->sighand->siglock);
230 old = tsk->signal->session_keyring;
231 rcu_assign_pointer(tsk->signal->session_keyring, keyring);
232 spin_unlock_irq(&tsk->sighand->siglock);
234 /* we're using RCU on the pointer, but there's no point synchronising
235 * on it if it didn't previously point to anything */
243 } /* end install_session_keyring() */
245 /*****************************************************************************/
247 * copy the keys in a thread group for fork without CLONE_THREAD
249 int copy_thread_group_keys(struct task_struct *tsk)
251 key_check(current->thread_group->session_keyring);
252 key_check(current->thread_group->process_keyring);
254 /* no process keyring yet */
255 tsk->signal->process_keyring = NULL;
257 /* same session keyring */
259 tsk->signal->session_keyring =
260 key_get(rcu_dereference(current->signal->session_keyring));
265 } /* end copy_thread_group_keys() */
267 /*****************************************************************************/
269 * copy the keys for fork
271 int copy_keys(unsigned long clone_flags, struct task_struct *tsk)
273 key_check(tsk->thread_keyring);
274 key_check(tsk->request_key_auth);
276 /* no thread keyring yet */
277 tsk->thread_keyring = NULL;
279 /* copy the request_key() authorisation for this thread */
280 key_get(tsk->request_key_auth);
284 } /* end copy_keys() */
286 /*****************************************************************************/
288 * dispose of thread group keys upon thread group destruction
290 void exit_thread_group_keys(struct signal_struct *tg)
292 key_put(tg->session_keyring);
293 key_put(tg->process_keyring);
295 } /* end exit_thread_group_keys() */
297 /*****************************************************************************/
299 * dispose of per-thread keys upon thread exit
301 void exit_keys(struct task_struct *tsk)
303 key_put(tsk->thread_keyring);
304 key_put(tsk->request_key_auth);
306 } /* end exit_keys() */
308 /*****************************************************************************/
312 int exec_keys(struct task_struct *tsk)
316 /* newly exec'd tasks don't get a thread keyring */
318 old = tsk->thread_keyring;
319 tsk->thread_keyring = NULL;
324 /* discard the process keyring from a newly exec'd task */
325 spin_lock_irq(&tsk->sighand->siglock);
326 old = tsk->signal->process_keyring;
327 tsk->signal->process_keyring = NULL;
328 spin_unlock_irq(&tsk->sighand->siglock);
334 } /* end exec_keys() */
336 /*****************************************************************************/
338 * deal with SUID programs
339 * - we might want to make this invent a new session keyring
341 int suid_keys(struct task_struct *tsk)
345 } /* end suid_keys() */
347 /*****************************************************************************/
349 * the filesystem user ID changed
351 void key_fsuid_changed(struct task_struct *tsk)
353 /* update the ownership of the thread keyring */
354 if (tsk->thread_keyring) {
355 down_write(&tsk->thread_keyring->sem);
356 tsk->thread_keyring->uid = tsk->fsuid;
357 up_write(&tsk->thread_keyring->sem);
360 } /* end key_fsuid_changed() */
362 /*****************************************************************************/
364 * the filesystem group ID changed
366 void key_fsgid_changed(struct task_struct *tsk)
368 /* update the ownership of the thread keyring */
369 if (tsk->thread_keyring) {
370 down_write(&tsk->thread_keyring->sem);
371 tsk->thread_keyring->gid = tsk->fsgid;
372 up_write(&tsk->thread_keyring->sem);
375 } /* end key_fsgid_changed() */
377 /*****************************************************************************/
379 * search the process keyrings for the first matching key
380 * - we use the supplied match function to see if the description (or other
381 * feature of interest) matches
382 * - we return -EAGAIN if we didn't find any matching key
383 * - we return -ENOKEY if we found only negative matching keys
385 key_ref_t search_process_keyrings(struct key_type *type,
386 const void *description,
387 key_match_func_t match,
388 struct task_struct *context)
390 struct request_key_auth *rka;
391 key_ref_t key_ref, ret, err;
393 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
394 * searchable, but we failed to find a key or we found a negative key;
395 * otherwise we want to return a sample error (probably -EACCES) if
396 * none of the keyrings were searchable
398 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
402 err = ERR_PTR(-EAGAIN);
404 /* search the thread keyring first */
405 if (context->thread_keyring) {
406 key_ref = keyring_search_aux(
407 make_key_ref(context->thread_keyring, 1),
408 context, type, description, match);
409 if (!IS_ERR(key_ref))
412 switch (PTR_ERR(key_ref)) {
413 case -EAGAIN: /* no key */
416 case -ENOKEY: /* negative key */
425 /* search the process keyring second */
426 if (context->signal->process_keyring) {
427 key_ref = keyring_search_aux(
428 make_key_ref(context->signal->process_keyring, 1),
429 context, type, description, match);
430 if (!IS_ERR(key_ref))
433 switch (PTR_ERR(key_ref)) {
434 case -EAGAIN: /* no key */
437 case -ENOKEY: /* negative key */
446 /* search the session keyring */
447 if (context->signal->session_keyring) {
449 key_ref = keyring_search_aux(
450 make_key_ref(rcu_dereference(
451 context->signal->session_keyring),
453 context, type, description, match);
456 if (!IS_ERR(key_ref))
459 switch (PTR_ERR(key_ref)) {
460 case -EAGAIN: /* no key */
463 case -ENOKEY: /* negative key */
471 /* or search the user-session keyring */
473 key_ref = keyring_search_aux(
474 make_key_ref(context->user->session_keyring, 1),
475 context, type, description, match);
476 if (!IS_ERR(key_ref))
479 switch (PTR_ERR(key_ref)) {
480 case -EAGAIN: /* no key */
483 case -ENOKEY: /* negative key */
492 /* if this process has an instantiation authorisation key, then we also
493 * search the keyrings of the process mentioned there
494 * - we don't permit access to request_key auth keys via this method
496 if (context->request_key_auth &&
497 context == current &&
498 type != &key_type_request_key_auth &&
499 key_validate(context->request_key_auth) == 0
501 rka = context->request_key_auth->payload.data;
503 key_ref = search_process_keyrings(type, description, match,
506 if (!IS_ERR(key_ref))
509 switch (PTR_ERR(key_ref)) {
510 case -EAGAIN: /* no key */
513 case -ENOKEY: /* negative key */
522 /* no key - decide on the error we're going to go for */
523 key_ref = ret ? ret : err;
528 } /* end search_process_keyrings() */
530 /*****************************************************************************/
532 * see if the key we're looking at is the target key
534 static int lookup_user_key_possessed(const struct key *key, const void *target)
536 return key == target;
538 } /* end lookup_user_key_possessed() */
540 /*****************************************************************************/
542 * lookup a key given a key ID from userspace with a given permissions mask
543 * - don't create special keyrings unless so requested
544 * - partially constructed keys aren't found unless requested
546 key_ref_t lookup_user_key(struct task_struct *context, key_serial_t id,
547 int create, int partial, key_perm_t perm)
549 key_ref_t key_ref, skey_ref;
556 key_ref = ERR_PTR(-ENOKEY);
559 case KEY_SPEC_THREAD_KEYRING:
560 if (!context->thread_keyring) {
564 ret = install_thread_keyring(context);
571 key = context->thread_keyring;
572 atomic_inc(&key->usage);
573 key_ref = make_key_ref(key, 1);
576 case KEY_SPEC_PROCESS_KEYRING:
577 if (!context->signal->process_keyring) {
581 ret = install_process_keyring(context);
588 key = context->signal->process_keyring;
589 atomic_inc(&key->usage);
590 key_ref = make_key_ref(key, 1);
593 case KEY_SPEC_SESSION_KEYRING:
594 if (!context->signal->session_keyring) {
595 /* always install a session keyring upon access if one
596 * doesn't exist yet */
597 ret = install_session_keyring(
598 context, context->user->session_keyring);
604 key = rcu_dereference(context->signal->session_keyring);
605 atomic_inc(&key->usage);
607 key_ref = make_key_ref(key, 1);
610 case KEY_SPEC_USER_KEYRING:
611 key = context->user->uid_keyring;
612 atomic_inc(&key->usage);
613 key_ref = make_key_ref(key, 1);
616 case KEY_SPEC_USER_SESSION_KEYRING:
617 key = context->user->session_keyring;
618 atomic_inc(&key->usage);
619 key_ref = make_key_ref(key, 1);
622 case KEY_SPEC_GROUP_KEYRING:
623 /* group keyrings are not yet supported */
624 key = ERR_PTR(-EINVAL);
627 case KEY_SPEC_REQKEY_AUTH_KEY:
628 key = context->request_key_auth;
632 atomic_inc(&key->usage);
633 key_ref = make_key_ref(key, 1);
637 key_ref = ERR_PTR(-EINVAL);
641 key = key_lookup(id);
643 key_ref = ERR_PTR(PTR_ERR(key));
647 key_ref = make_key_ref(key, 0);
649 /* check to see if we possess the key */
650 skey_ref = search_process_keyrings(key->type, key,
651 lookup_user_key_possessed,
654 if (!IS_ERR(skey_ref)) {
662 /* check the status */
664 ret = key_validate(key);
670 if (!partial && !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
673 /* check the permissions */
674 ret = key_task_permission(key_ref, context, perm);
682 key_ref_put(key_ref);
683 key_ref = ERR_PTR(ret);
686 } /* end lookup_user_key() */
688 /*****************************************************************************/
690 * join the named keyring as the session keyring if possible, or attempt to
691 * create a new one of that name if not
692 * - if the name is NULL, an empty anonymous keyring is installed instead
693 * - named session keyring joining is done with a semaphore held
695 long join_session_keyring(const char *name)
697 struct task_struct *tsk = current;
701 /* if no name is provided, install an anonymous keyring */
703 ret = install_session_keyring(tsk, NULL);
708 ret = rcu_dereference(tsk->signal->session_keyring)->serial;
713 /* allow the user to join or create a named keyring */
714 mutex_lock(&key_session_mutex);
716 /* look for an existing keyring of this name */
717 keyring = find_keyring_by_name(name, 0);
718 if (PTR_ERR(keyring) == -ENOKEY) {
719 /* not found - try and create a new one */
720 keyring = keyring_alloc(name, tsk->uid, tsk->gid, 0, NULL);
721 if (IS_ERR(keyring)) {
722 ret = PTR_ERR(keyring);
726 else if (IS_ERR(keyring)) {
727 ret = PTR_ERR(keyring);
731 /* we've got a keyring - now to install it */
732 ret = install_session_keyring(tsk, keyring);
736 ret = keyring->serial;
740 mutex_unlock(&key_session_mutex);
744 } /* end join_session_keyring() */