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)
176 if (!tsk->signal->process_keyring) {
177 sprintf(buf, "_pid.%u", tsk->tgid);
179 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
180 if (IS_ERR(keyring)) {
181 ret = PTR_ERR(keyring);
186 spin_lock_irqsave(&tsk->sighand->siglock, flags);
187 if (!tsk->signal->process_keyring) {
188 tsk->signal->process_keyring = keyring;
191 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
200 } /* end install_process_keyring() */
202 /*****************************************************************************/
204 * install a session keyring, discarding the old one
205 * - if a keyring is not supplied, an empty one is invented
207 static int install_session_keyring(struct task_struct *tsk,
215 /* create an empty session keyring */
217 sprintf(buf, "_ses.%u", tsk->tgid);
219 keyring = keyring_alloc(buf, tsk->uid, tsk->gid, 1, NULL);
220 if (IS_ERR(keyring)) {
221 ret = PTR_ERR(keyring);
226 atomic_inc(&keyring->usage);
229 /* install the keyring */
230 spin_lock_irqsave(&tsk->sighand->siglock, flags);
231 old = rcu_dereference(tsk->signal->session_keyring);
232 rcu_assign_pointer(tsk->signal->session_keyring, keyring);
233 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
237 /* we're using RCU on the pointer */
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)
317 /* newly exec'd tasks don't get a thread keyring */
319 old = tsk->thread_keyring;
320 tsk->thread_keyring = NULL;
325 /* discard the process keyring from a newly exec'd task */
326 spin_lock_irqsave(&tsk->sighand->siglock, flags);
327 old = tsk->signal->process_keyring;
328 tsk->signal->process_keyring = NULL;
329 spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
335 } /* end exec_keys() */
337 /*****************************************************************************/
339 * deal with SUID programs
340 * - we might want to make this invent a new session keyring
342 int suid_keys(struct task_struct *tsk)
346 } /* end suid_keys() */
348 /*****************************************************************************/
350 * the filesystem user ID changed
352 void key_fsuid_changed(struct task_struct *tsk)
354 /* update the ownership of the thread keyring */
355 if (tsk->thread_keyring) {
356 down_write(&tsk->thread_keyring->sem);
357 tsk->thread_keyring->uid = tsk->fsuid;
358 up_write(&tsk->thread_keyring->sem);
361 } /* end key_fsuid_changed() */
363 /*****************************************************************************/
365 * the filesystem group ID changed
367 void key_fsgid_changed(struct task_struct *tsk)
369 /* update the ownership of the thread keyring */
370 if (tsk->thread_keyring) {
371 down_write(&tsk->thread_keyring->sem);
372 tsk->thread_keyring->gid = tsk->fsgid;
373 up_write(&tsk->thread_keyring->sem);
376 } /* end key_fsgid_changed() */
378 /*****************************************************************************/
380 * search the process keyrings for the first matching key
381 * - we use the supplied match function to see if the description (or other
382 * feature of interest) matches
383 * - we return -EAGAIN if we didn't find any matching key
384 * - we return -ENOKEY if we found only negative matching keys
386 key_ref_t search_process_keyrings(struct key_type *type,
387 const void *description,
388 key_match_func_t match,
389 struct task_struct *context)
391 struct request_key_auth *rka;
392 key_ref_t key_ref, ret, err;
394 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
395 * searchable, but we failed to find a key or we found a negative key;
396 * otherwise we want to return a sample error (probably -EACCES) if
397 * none of the keyrings were searchable
399 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
403 err = ERR_PTR(-EAGAIN);
405 /* search the thread keyring first */
406 if (context->thread_keyring) {
407 key_ref = keyring_search_aux(
408 make_key_ref(context->thread_keyring, 1),
409 context, type, description, match);
410 if (!IS_ERR(key_ref))
413 switch (PTR_ERR(key_ref)) {
414 case -EAGAIN: /* no key */
417 case -ENOKEY: /* negative key */
426 /* search the process keyring second */
427 if (context->signal->process_keyring) {
428 key_ref = keyring_search_aux(
429 make_key_ref(context->signal->process_keyring, 1),
430 context, type, description, match);
431 if (!IS_ERR(key_ref))
434 switch (PTR_ERR(key_ref)) {
435 case -EAGAIN: /* no key */
438 case -ENOKEY: /* negative key */
447 /* search the session keyring */
448 if (context->signal->session_keyring) {
450 key_ref = keyring_search_aux(
451 make_key_ref(rcu_dereference(
452 context->signal->session_keyring),
454 context, type, description, match);
457 if (!IS_ERR(key_ref))
460 switch (PTR_ERR(key_ref)) {
461 case -EAGAIN: /* no key */
464 case -ENOKEY: /* negative key */
472 /* or search the user-session keyring */
474 key_ref = keyring_search_aux(
475 make_key_ref(context->user->session_keyring, 1),
476 context, type, description, match);
477 if (!IS_ERR(key_ref))
480 switch (PTR_ERR(key_ref)) {
481 case -EAGAIN: /* no key */
484 case -ENOKEY: /* negative key */
493 /* if this process has an instantiation authorisation key, then we also
494 * search the keyrings of the process mentioned there
495 * - we don't permit access to request_key auth keys via this method
497 if (context->request_key_auth &&
498 context == current &&
499 type != &key_type_request_key_auth &&
500 key_validate(context->request_key_auth) == 0
502 rka = context->request_key_auth->payload.data;
504 key_ref = search_process_keyrings(type, description, match,
507 if (!IS_ERR(key_ref))
510 switch (PTR_ERR(key_ref)) {
511 case -EAGAIN: /* no key */
514 case -ENOKEY: /* negative key */
523 /* no key - decide on the error we're going to go for */
524 key_ref = ret ? ret : err;
529 } /* end search_process_keyrings() */
531 /*****************************************************************************/
533 * see if the key we're looking at is the target key
535 static int lookup_user_key_possessed(const struct key *key, const void *target)
537 return key == target;
539 } /* end lookup_user_key_possessed() */
541 /*****************************************************************************/
543 * lookup a key given a key ID from userspace with a given permissions mask
544 * - don't create special keyrings unless so requested
545 * - partially constructed keys aren't found unless requested
547 key_ref_t lookup_user_key(struct task_struct *context, key_serial_t id,
548 int create, int partial, key_perm_t perm)
550 key_ref_t key_ref, skey_ref;
557 key_ref = ERR_PTR(-ENOKEY);
560 case KEY_SPEC_THREAD_KEYRING:
561 if (!context->thread_keyring) {
565 ret = install_thread_keyring(context);
572 key = context->thread_keyring;
573 atomic_inc(&key->usage);
574 key_ref = make_key_ref(key, 1);
577 case KEY_SPEC_PROCESS_KEYRING:
578 if (!context->signal->process_keyring) {
582 ret = install_process_keyring(context);
589 key = context->signal->process_keyring;
590 atomic_inc(&key->usage);
591 key_ref = make_key_ref(key, 1);
594 case KEY_SPEC_SESSION_KEYRING:
595 if (!context->signal->session_keyring) {
596 /* always install a session keyring upon access if one
597 * doesn't exist yet */
598 ret = install_session_keyring(
599 context, context->user->session_keyring);
605 key = rcu_dereference(context->signal->session_keyring);
606 atomic_inc(&key->usage);
608 key_ref = make_key_ref(key, 1);
611 case KEY_SPEC_USER_KEYRING:
612 key = context->user->uid_keyring;
613 atomic_inc(&key->usage);
614 key_ref = make_key_ref(key, 1);
617 case KEY_SPEC_USER_SESSION_KEYRING:
618 key = context->user->session_keyring;
619 atomic_inc(&key->usage);
620 key_ref = make_key_ref(key, 1);
623 case KEY_SPEC_GROUP_KEYRING:
624 /* group keyrings are not yet supported */
625 key = ERR_PTR(-EINVAL);
628 case KEY_SPEC_REQKEY_AUTH_KEY:
629 key = context->request_key_auth;
633 atomic_inc(&key->usage);
634 key_ref = make_key_ref(key, 1);
638 key_ref = ERR_PTR(-EINVAL);
642 key = key_lookup(id);
644 key_ref = ERR_PTR(PTR_ERR(key));
648 key_ref = make_key_ref(key, 0);
650 /* check to see if we possess the key */
651 skey_ref = search_process_keyrings(key->type, key,
652 lookup_user_key_possessed,
655 if (!IS_ERR(skey_ref)) {
663 /* check the status */
665 ret = key_validate(key);
671 if (!partial && !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
674 /* check the permissions */
675 ret = key_task_permission(key_ref, context, perm);
683 key_ref_put(key_ref);
684 key_ref = ERR_PTR(ret);
687 } /* end lookup_user_key() */
689 /*****************************************************************************/
691 * join the named keyring as the session keyring if possible, or attempt to
692 * create a new one of that name if not
693 * - if the name is NULL, an empty anonymous keyring is installed instead
694 * - named session keyring joining is done with a semaphore held
696 long join_session_keyring(const char *name)
698 struct task_struct *tsk = current;
702 /* if no name is provided, install an anonymous keyring */
704 ret = install_session_keyring(tsk, NULL);
709 ret = rcu_dereference(tsk->signal->session_keyring)->serial;
714 /* allow the user to join or create a named keyring */
715 mutex_lock(&key_session_mutex);
717 /* look for an existing keyring of this name */
718 keyring = find_keyring_by_name(name, 0);
719 if (PTR_ERR(keyring) == -ENOKEY) {
720 /* not found - try and create a new one */
721 keyring = keyring_alloc(name, tsk->uid, tsk->gid, 0, NULL);
722 if (IS_ERR(keyring)) {
723 ret = PTR_ERR(keyring);
727 else if (IS_ERR(keyring)) {
728 ret = PTR_ERR(keyring);
732 /* we've got a keyring - now to install it */
733 ret = install_session_keyring(tsk, keyring);
737 ret = keyring->serial;
741 mutex_unlock(&key_session_mutex);
745 } /* end join_session_keyring() */