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() */