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
,
71 struct task_struct
*ctx
)
73 struct key
*uid_keyring
, *session_keyring
;
77 /* concoct a default session keyring */
78 sprintf(buf
, "_uid_ses.%u", user
->uid
);
80 session_keyring
= keyring_alloc(buf
, user
->uid
, (gid_t
) -1, ctx
, 0, NULL
);
81 if (IS_ERR(session_keyring
)) {
82 ret
= PTR_ERR(session_keyring
);
86 /* and a UID specific keyring, pointed to by the default session
88 sprintf(buf
, "_uid.%u", user
->uid
);
90 uid_keyring
= keyring_alloc(buf
, user
->uid
, (gid_t
) -1, ctx
, 0,
92 if (IS_ERR(uid_keyring
)) {
93 key_put(session_keyring
);
94 ret
= PTR_ERR(uid_keyring
);
98 /* install the keyrings */
99 user
->uid_keyring
= uid_keyring
;
100 user
->session_keyring
= session_keyring
;
106 } /* end alloc_uid_keyring() */
108 /*****************************************************************************/
110 * deal with the UID changing
112 void switch_uid_keyring(struct user_struct
*new_user
)
114 #if 0 /* do nothing for now */
117 /* switch to the new user's session keyring if we were running under
118 * root's default session keyring */
119 if (new_user
->uid
!= 0 &&
120 current
->session_keyring
== &root_session_keyring
122 atomic_inc(&new_user
->session_keyring
->usage
);
125 old
= current
->session_keyring
;
126 current
->session_keyring
= new_user
->session_keyring
;
127 task_unlock(current
);
133 } /* end switch_uid_keyring() */
135 /*****************************************************************************/
137 * install a fresh thread keyring, discarding the old one
139 int install_thread_keyring(struct task_struct
*tsk
)
141 struct key
*keyring
, *old
;
145 sprintf(buf
, "_tid.%u", tsk
->pid
);
147 keyring
= keyring_alloc(buf
, tsk
->uid
, tsk
->gid
, tsk
, 1, NULL
);
148 if (IS_ERR(keyring
)) {
149 ret
= PTR_ERR(keyring
);
154 old
= tsk
->thread_keyring
;
155 tsk
->thread_keyring
= keyring
;
164 } /* end install_thread_keyring() */
166 /*****************************************************************************/
168 * make sure a process keyring is installed
170 int install_process_keyring(struct task_struct
*tsk
)
178 if (!tsk
->signal
->process_keyring
) {
179 sprintf(buf
, "_pid.%u", tsk
->tgid
);
181 keyring
= keyring_alloc(buf
, tsk
->uid
, tsk
->gid
, tsk
, 1, NULL
);
182 if (IS_ERR(keyring
)) {
183 ret
= PTR_ERR(keyring
);
188 spin_lock_irq(&tsk
->sighand
->siglock
);
189 if (!tsk
->signal
->process_keyring
) {
190 tsk
->signal
->process_keyring
= keyring
;
193 spin_unlock_irq(&tsk
->sighand
->siglock
);
202 } /* end install_process_keyring() */
204 /*****************************************************************************/
206 * install a session keyring, discarding the old one
207 * - if a keyring is not supplied, an empty one is invented
209 static int install_session_keyring(struct task_struct
*tsk
,
217 /* create an empty session keyring */
219 sprintf(buf
, "_ses.%u", tsk
->tgid
);
221 keyring
= keyring_alloc(buf
, tsk
->uid
, tsk
->gid
, tsk
, 1, NULL
);
223 return PTR_ERR(keyring
);
226 atomic_inc(&keyring
->usage
);
229 /* install the keyring */
230 spin_lock_irq(&tsk
->sighand
->siglock
);
231 old
= tsk
->signal
->session_keyring
;
232 rcu_assign_pointer(tsk
->signal
->session_keyring
, keyring
);
233 spin_unlock_irq(&tsk
->sighand
->siglock
);
235 /* we're using RCU on the pointer, but there's no point synchronising
236 * on it if it didn't previously point to anything */
244 } /* end install_session_keyring() */
246 /*****************************************************************************/
248 * copy the keys in a thread group for fork without CLONE_THREAD
250 int copy_thread_group_keys(struct task_struct
*tsk
)
252 key_check(current
->thread_group
->session_keyring
);
253 key_check(current
->thread_group
->process_keyring
);
255 /* no process keyring yet */
256 tsk
->signal
->process_keyring
= NULL
;
258 /* same session keyring */
260 tsk
->signal
->session_keyring
=
261 key_get(rcu_dereference(current
->signal
->session_keyring
));
266 } /* end copy_thread_group_keys() */
268 /*****************************************************************************/
270 * copy the keys for fork
272 int copy_keys(unsigned long clone_flags
, struct task_struct
*tsk
)
274 key_check(tsk
->thread_keyring
);
275 key_check(tsk
->request_key_auth
);
277 /* no thread keyring yet */
278 tsk
->thread_keyring
= NULL
;
280 /* copy the request_key() authorisation for this thread */
281 key_get(tsk
->request_key_auth
);
285 } /* end copy_keys() */
287 /*****************************************************************************/
289 * dispose of thread group keys upon thread group destruction
291 void exit_thread_group_keys(struct signal_struct
*tg
)
293 key_put(tg
->session_keyring
);
294 key_put(tg
->process_keyring
);
296 } /* end exit_thread_group_keys() */
298 /*****************************************************************************/
300 * dispose of per-thread keys upon thread exit
302 void exit_keys(struct task_struct
*tsk
)
304 key_put(tsk
->thread_keyring
);
305 key_put(tsk
->request_key_auth
);
307 } /* end exit_keys() */
309 /*****************************************************************************/
313 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_irq(&tsk
->sighand
->siglock
);
327 old
= tsk
->signal
->process_keyring
;
328 tsk
->signal
->process_keyring
= NULL
;
329 spin_unlock_irq(&tsk
->sighand
->siglock
);
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
;
396 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
397 * searchable, but we failed to find a key or we found a negative key;
398 * otherwise we want to return a sample error (probably -EACCES) if
399 * none of the keyrings were searchable
401 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
405 err
= ERR_PTR(-EAGAIN
);
407 /* search the thread keyring first */
408 if (context
->thread_keyring
) {
409 key_ref
= keyring_search_aux(
410 make_key_ref(context
->thread_keyring
, 1),
411 context
, type
, description
, match
);
412 if (!IS_ERR(key_ref
))
415 switch (PTR_ERR(key_ref
)) {
416 case -EAGAIN
: /* no key */
419 case -ENOKEY
: /* negative key */
428 /* search the process keyring second */
429 if (context
->signal
->process_keyring
) {
430 key_ref
= keyring_search_aux(
431 make_key_ref(context
->signal
->process_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 session keyring */
450 if (context
->signal
->session_keyring
) {
452 key_ref
= keyring_search_aux(
453 make_key_ref(rcu_dereference(
454 context
->signal
->session_keyring
),
456 context
, type
, description
, match
);
459 if (!IS_ERR(key_ref
))
462 switch (PTR_ERR(key_ref
)) {
463 case -EAGAIN
: /* no key */
466 case -ENOKEY
: /* negative key */
474 /* or search the user-session keyring */
476 key_ref
= keyring_search_aux(
477 make_key_ref(context
->user
->session_keyring
, 1),
478 context
, type
, description
, match
);
479 if (!IS_ERR(key_ref
))
482 switch (PTR_ERR(key_ref
)) {
483 case -EAGAIN
: /* no key */
486 case -ENOKEY
: /* negative key */
495 /* if this process has an instantiation authorisation key, then we also
496 * search the keyrings of the process mentioned there
497 * - we don't permit access to request_key auth keys via this method
499 if (context
->request_key_auth
&&
500 context
== current
&&
501 type
!= &key_type_request_key_auth
503 /* defend against the auth key being revoked */
504 down_read(&context
->request_key_auth
->sem
);
506 if (key_validate(context
->request_key_auth
) == 0) {
507 rka
= context
->request_key_auth
->payload
.data
;
509 key_ref
= search_process_keyrings(type
, description
,
510 match
, rka
->context
);
512 up_read(&context
->request_key_auth
->sem
);
514 if (!IS_ERR(key_ref
))
517 switch (PTR_ERR(key_ref
)) {
518 case -EAGAIN
: /* no key */
521 case -ENOKEY
: /* negative key */
529 up_read(&context
->request_key_auth
->sem
);
533 /* no key - decide on the error we're going to go for */
534 key_ref
= ret
? ret
: err
;
539 } /* end search_process_keyrings() */
541 /*****************************************************************************/
543 * see if the key we're looking at is the target key
545 static int lookup_user_key_possessed(const struct key
*key
, const void *target
)
547 return key
== target
;
549 } /* end lookup_user_key_possessed() */
551 /*****************************************************************************/
553 * lookup a key given a key ID from userspace with a given permissions mask
554 * - don't create special keyrings unless so requested
555 * - partially constructed keys aren't found unless requested
557 key_ref_t
lookup_user_key(struct task_struct
*context
, key_serial_t id
,
558 int create
, int partial
, key_perm_t perm
)
560 key_ref_t key_ref
, skey_ref
;
567 key_ref
= ERR_PTR(-ENOKEY
);
570 case KEY_SPEC_THREAD_KEYRING
:
571 if (!context
->thread_keyring
) {
575 ret
= install_thread_keyring(context
);
582 key
= context
->thread_keyring
;
583 atomic_inc(&key
->usage
);
584 key_ref
= make_key_ref(key
, 1);
587 case KEY_SPEC_PROCESS_KEYRING
:
588 if (!context
->signal
->process_keyring
) {
592 ret
= install_process_keyring(context
);
599 key
= context
->signal
->process_keyring
;
600 atomic_inc(&key
->usage
);
601 key_ref
= make_key_ref(key
, 1);
604 case KEY_SPEC_SESSION_KEYRING
:
605 if (!context
->signal
->session_keyring
) {
606 /* always install a session keyring upon access if one
607 * doesn't exist yet */
608 ret
= install_session_keyring(
609 context
, context
->user
->session_keyring
);
615 key
= rcu_dereference(context
->signal
->session_keyring
);
616 atomic_inc(&key
->usage
);
618 key_ref
= make_key_ref(key
, 1);
621 case KEY_SPEC_USER_KEYRING
:
622 key
= context
->user
->uid_keyring
;
623 atomic_inc(&key
->usage
);
624 key_ref
= make_key_ref(key
, 1);
627 case KEY_SPEC_USER_SESSION_KEYRING
:
628 key
= context
->user
->session_keyring
;
629 atomic_inc(&key
->usage
);
630 key_ref
= make_key_ref(key
, 1);
633 case KEY_SPEC_GROUP_KEYRING
:
634 /* group keyrings are not yet supported */
635 key
= ERR_PTR(-EINVAL
);
638 case KEY_SPEC_REQKEY_AUTH_KEY
:
639 key
= context
->request_key_auth
;
643 atomic_inc(&key
->usage
);
644 key_ref
= make_key_ref(key
, 1);
648 key_ref
= ERR_PTR(-EINVAL
);
652 key
= key_lookup(id
);
654 key_ref
= ERR_PTR(PTR_ERR(key
));
658 key_ref
= make_key_ref(key
, 0);
660 /* check to see if we possess the key */
661 skey_ref
= search_process_keyrings(key
->type
, key
,
662 lookup_user_key_possessed
,
665 if (!IS_ERR(skey_ref
)) {
673 /* check the status */
675 ret
= key_validate(key
);
681 if (!partial
&& !test_bit(KEY_FLAG_INSTANTIATED
, &key
->flags
))
684 /* check the permissions */
685 ret
= key_task_permission(key_ref
, context
, perm
);
693 key_ref_put(key_ref
);
694 key_ref
= ERR_PTR(ret
);
697 } /* end lookup_user_key() */
699 /*****************************************************************************/
701 * join the named keyring as the session keyring if possible, or attempt to
702 * create a new one of that name if not
703 * - if the name is NULL, an empty anonymous keyring is installed instead
704 * - named session keyring joining is done with a semaphore held
706 long join_session_keyring(const char *name
)
708 struct task_struct
*tsk
= current
;
712 /* if no name is provided, install an anonymous keyring */
714 ret
= install_session_keyring(tsk
, NULL
);
719 ret
= rcu_dereference(tsk
->signal
->session_keyring
)->serial
;
724 /* allow the user to join or create a named keyring */
725 mutex_lock(&key_session_mutex
);
727 /* look for an existing keyring of this name */
728 keyring
= find_keyring_by_name(name
, 0);
729 if (PTR_ERR(keyring
) == -ENOKEY
) {
730 /* not found - try and create a new one */
731 keyring
= keyring_alloc(name
, tsk
->uid
, tsk
->gid
, tsk
, 0, NULL
);
732 if (IS_ERR(keyring
)) {
733 ret
= PTR_ERR(keyring
);
737 else if (IS_ERR(keyring
)) {
738 ret
= PTR_ERR(keyring
);
742 /* we've got a keyring - now to install it */
743 ret
= install_session_keyring(tsk
, keyring
);
747 ret
= keyring
->serial
;
751 mutex_unlock(&key_session_mutex
);
755 } /* end join_session_keyring() */