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 <asm/uaccess.h>
22 /* session keyring create vs join semaphore */
23 static DECLARE_MUTEX(key_session_sem
);
25 /* the root user's tracking struct */
26 struct key_user root_key_user
= {
27 .usage
= ATOMIC_INIT(3),
28 .consq
= LIST_HEAD_INIT(root_key_user
.consq
),
29 .lock
= SPIN_LOCK_UNLOCKED
,
30 .nkeys
= ATOMIC_INIT(2),
31 .nikeys
= ATOMIC_INIT(2),
35 /* the root user's UID keyring */
36 struct key root_user_keyring
= {
37 .usage
= ATOMIC_INIT(1),
39 .type
= &key_type_keyring
,
40 .user
= &root_key_user
,
41 .sem
= __RWSEM_INITIALIZER(root_user_keyring
.sem
),
42 .perm
= (KEY_POS_ALL
& ~KEY_POS_SETATTR
) | KEY_USR_ALL
,
43 .flags
= 1 << KEY_FLAG_INSTANTIATED
,
44 .description
= "_uid.0",
46 .magic
= KEY_DEBUG_MAGIC
,
50 /* the root user's default session keyring */
51 struct key root_session_keyring
= {
52 .usage
= ATOMIC_INIT(1),
54 .type
= &key_type_keyring
,
55 .user
= &root_key_user
,
56 .sem
= __RWSEM_INITIALIZER(root_session_keyring
.sem
),
57 .perm
= (KEY_POS_ALL
& ~KEY_POS_SETATTR
) | KEY_USR_ALL
,
58 .flags
= 1 << KEY_FLAG_INSTANTIATED
,
59 .description
= "_uid_ses.0",
61 .magic
= KEY_DEBUG_MAGIC
,
65 /*****************************************************************************/
67 * allocate the keyrings to be associated with a UID
69 int alloc_uid_keyring(struct user_struct
*user
)
71 struct key
*uid_keyring
, *session_keyring
;
75 /* concoct a default session keyring */
76 sprintf(buf
, "_uid_ses.%u", user
->uid
);
78 session_keyring
= keyring_alloc(buf
, user
->uid
, (gid_t
) -1, 0, NULL
);
79 if (IS_ERR(session_keyring
)) {
80 ret
= PTR_ERR(session_keyring
);
84 /* and a UID specific keyring, pointed to by the default session
86 sprintf(buf
, "_uid.%u", user
->uid
);
88 uid_keyring
= keyring_alloc(buf
, user
->uid
, (gid_t
) -1, 0,
90 if (IS_ERR(uid_keyring
)) {
91 key_put(session_keyring
);
92 ret
= PTR_ERR(uid_keyring
);
96 /* install the keyrings */
97 user
->uid_keyring
= uid_keyring
;
98 user
->session_keyring
= session_keyring
;
104 } /* end alloc_uid_keyring() */
106 /*****************************************************************************/
108 * deal with the UID changing
110 void switch_uid_keyring(struct user_struct
*new_user
)
112 #if 0 /* do nothing for now */
115 /* switch to the new user's session keyring if we were running under
116 * root's default session keyring */
117 if (new_user
->uid
!= 0 &&
118 current
->session_keyring
== &root_session_keyring
120 atomic_inc(&new_user
->session_keyring
->usage
);
123 old
= current
->session_keyring
;
124 current
->session_keyring
= new_user
->session_keyring
;
125 task_unlock(current
);
131 } /* end switch_uid_keyring() */
133 /*****************************************************************************/
135 * install a fresh thread keyring, discarding the old one
137 int install_thread_keyring(struct task_struct
*tsk
)
139 struct key
*keyring
, *old
;
143 sprintf(buf
, "_tid.%u", tsk
->pid
);
145 keyring
= keyring_alloc(buf
, tsk
->uid
, tsk
->gid
, 1, NULL
);
146 if (IS_ERR(keyring
)) {
147 ret
= PTR_ERR(keyring
);
152 old
= tsk
->thread_keyring
;
153 tsk
->thread_keyring
= keyring
;
162 } /* end install_thread_keyring() */
164 /*****************************************************************************/
166 * make sure a process keyring is installed
168 int install_process_keyring(struct task_struct
*tsk
)
175 if (!tsk
->signal
->process_keyring
) {
176 sprintf(buf
, "_pid.%u", tsk
->tgid
);
178 keyring
= keyring_alloc(buf
, tsk
->uid
, tsk
->gid
, 1, NULL
);
179 if (IS_ERR(keyring
)) {
180 ret
= PTR_ERR(keyring
);
185 spin_lock_irqsave(&tsk
->sighand
->siglock
, flags
);
186 if (!tsk
->signal
->process_keyring
) {
187 tsk
->signal
->process_keyring
= keyring
;
190 spin_unlock_irqrestore(&tsk
->sighand
->siglock
, flags
);
199 } /* end install_process_keyring() */
201 /*****************************************************************************/
203 * install a session keyring, discarding the old one
204 * - if a keyring is not supplied, an empty one is invented
206 static int install_session_keyring(struct task_struct
*tsk
,
214 /* create an empty session keyring */
216 sprintf(buf
, "_ses.%u", tsk
->tgid
);
218 keyring
= keyring_alloc(buf
, tsk
->uid
, tsk
->gid
, 1, NULL
);
219 if (IS_ERR(keyring
)) {
220 ret
= PTR_ERR(keyring
);
225 atomic_inc(&keyring
->usage
);
228 /* install the keyring */
229 spin_lock_irqsave(&tsk
->sighand
->siglock
, flags
);
230 old
= rcu_dereference(tsk
->signal
->session_keyring
);
231 rcu_assign_pointer(tsk
->signal
->session_keyring
, keyring
);
232 spin_unlock_irqrestore(&tsk
->sighand
->siglock
, flags
);
236 /* we're using RCU on the pointer */
242 } /* end install_session_keyring() */
244 /*****************************************************************************/
246 * copy the keys in a thread group for fork without CLONE_THREAD
248 int copy_thread_group_keys(struct task_struct
*tsk
)
250 key_check(current
->thread_group
->session_keyring
);
251 key_check(current
->thread_group
->process_keyring
);
253 /* no process keyring yet */
254 tsk
->signal
->process_keyring
= NULL
;
256 /* same session keyring */
258 tsk
->signal
->session_keyring
=
259 key_get(rcu_dereference(current
->signal
->session_keyring
));
264 } /* end copy_thread_group_keys() */
266 /*****************************************************************************/
268 * copy the keys for fork
270 int copy_keys(unsigned long clone_flags
, struct task_struct
*tsk
)
272 key_check(tsk
->thread_keyring
);
273 key_check(tsk
->request_key_auth
);
275 /* no thread keyring yet */
276 tsk
->thread_keyring
= NULL
;
278 /* copy the request_key() authorisation for this thread */
279 key_get(tsk
->request_key_auth
);
283 } /* end copy_keys() */
285 /*****************************************************************************/
287 * dispose of thread group keys upon thread group destruction
289 void exit_thread_group_keys(struct signal_struct
*tg
)
291 key_put(tg
->session_keyring
);
292 key_put(tg
->process_keyring
);
294 } /* end exit_thread_group_keys() */
296 /*****************************************************************************/
298 * dispose of per-thread keys upon thread exit
300 void exit_keys(struct task_struct
*tsk
)
302 key_put(tsk
->thread_keyring
);
303 key_put(tsk
->request_key_auth
);
305 } /* end exit_keys() */
307 /*****************************************************************************/
311 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_irqsave(&tsk
->sighand
->siglock
, flags
);
326 old
= tsk
->signal
->process_keyring
;
327 tsk
->signal
->process_keyring
= NULL
;
328 spin_unlock_irqrestore(&tsk
->sighand
->siglock
, flags
);
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 down(&key_session_sem
);
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 up(&key_session_sem
);
744 } /* end join_session_keyring() */