1 /* Manage a process's keyrings
3 * Copyright (C) 2004-2005, 2008 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/sched/user.h>
16 #include <linux/keyctl.h>
18 #include <linux/err.h>
19 #include <linux/mutex.h>
20 #include <linux/security.h>
21 #include <linux/user_namespace.h>
22 #include <linux/uaccess.h>
25 /* Session keyring create vs join semaphore */
26 static DEFINE_MUTEX(key_session_mutex
);
28 /* User keyring creation semaphore */
29 static DEFINE_MUTEX(key_user_keyring_mutex
);
31 /* The root user's tracking struct */
32 struct key_user root_key_user
= {
33 .usage
= ATOMIC_INIT(3),
34 .cons_lock
= __MUTEX_INITIALIZER(root_key_user
.cons_lock
),
35 .lock
= __SPIN_LOCK_UNLOCKED(root_key_user
.lock
),
36 .nkeys
= ATOMIC_INIT(2),
37 .nikeys
= ATOMIC_INIT(2),
38 .uid
= GLOBAL_ROOT_UID
,
42 * Install the user and user session keyrings for the current process's UID.
44 int install_user_keyrings(void)
46 struct user_struct
*user
;
47 const struct cred
*cred
;
48 struct key
*uid_keyring
, *session_keyring
;
49 key_perm_t user_keyring_perm
;
54 user_keyring_perm
= (KEY_POS_ALL
& ~KEY_POS_SETATTR
) | KEY_USR_ALL
;
55 cred
= current_cred();
57 uid
= from_kuid(cred
->user_ns
, user
->uid
);
59 kenter("%p{%u}", user
, uid
);
61 if (user
->uid_keyring
&& user
->session_keyring
) {
62 kleave(" = 0 [exist]");
66 mutex_lock(&key_user_keyring_mutex
);
69 if (!user
->uid_keyring
) {
70 /* get the UID-specific keyring
71 * - there may be one in existence already as it may have been
72 * pinned by a session, but the user_struct pointing to it
73 * may have been destroyed by setuid */
74 sprintf(buf
, "_uid.%u", uid
);
76 uid_keyring
= find_keyring_by_name(buf
, true);
77 if (IS_ERR(uid_keyring
)) {
78 uid_keyring
= keyring_alloc(buf
, user
->uid
, INVALID_GID
,
79 cred
, user_keyring_perm
,
82 if (IS_ERR(uid_keyring
)) {
83 ret
= PTR_ERR(uid_keyring
);
88 /* get a default session keyring (which might also exist
90 sprintf(buf
, "_uid_ses.%u", uid
);
92 session_keyring
= find_keyring_by_name(buf
, true);
93 if (IS_ERR(session_keyring
)) {
95 keyring_alloc(buf
, user
->uid
, INVALID_GID
,
96 cred
, user_keyring_perm
,
99 if (IS_ERR(session_keyring
)) {
100 ret
= PTR_ERR(session_keyring
);
104 /* we install a link from the user session keyring to
105 * the user keyring */
106 ret
= key_link(session_keyring
, uid_keyring
);
108 goto error_release_both
;
111 /* install the keyrings */
112 user
->uid_keyring
= uid_keyring
;
113 user
->session_keyring
= session_keyring
;
116 mutex_unlock(&key_user_keyring_mutex
);
121 key_put(session_keyring
);
123 key_put(uid_keyring
);
125 mutex_unlock(&key_user_keyring_mutex
);
126 kleave(" = %d", ret
);
131 * Install a fresh thread keyring directly to new credentials. This keyring is
132 * allowed to overrun the quota.
134 int install_thread_keyring_to_cred(struct cred
*new)
138 keyring
= keyring_alloc("_tid", new->uid
, new->gid
, new,
139 KEY_POS_ALL
| KEY_USR_VIEW
,
140 KEY_ALLOC_QUOTA_OVERRUN
,
143 return PTR_ERR(keyring
);
145 new->thread_keyring
= keyring
;
150 * Install a fresh thread keyring, discarding the old one.
152 static int install_thread_keyring(void)
157 new = prepare_creds();
161 BUG_ON(new->thread_keyring
);
163 ret
= install_thread_keyring_to_cred(new);
169 return commit_creds(new);
173 * Install a process keyring directly to a credentials struct.
175 * Returns -EEXIST if there was already a process keyring, 0 if one installed,
176 * and other value on any other error
178 int install_process_keyring_to_cred(struct cred
*new)
182 if (new->process_keyring
)
185 keyring
= keyring_alloc("_pid", new->uid
, new->gid
, new,
186 KEY_POS_ALL
| KEY_USR_VIEW
,
187 KEY_ALLOC_QUOTA_OVERRUN
,
190 return PTR_ERR(keyring
);
192 new->process_keyring
= keyring
;
197 * Make sure a process keyring is installed for the current process. The
198 * existing process keyring is not replaced.
200 * Returns 0 if there is a process keyring by the end of this function, some
203 static int install_process_keyring(void)
208 new = prepare_creds();
212 ret
= install_process_keyring_to_cred(new);
215 return ret
!= -EEXIST
? ret
: 0;
218 return commit_creds(new);
222 * Install a session keyring directly to a credentials struct.
224 int install_session_keyring_to_cred(struct cred
*cred
, struct key
*keyring
)
231 /* create an empty session keyring */
233 flags
= KEY_ALLOC_QUOTA_OVERRUN
;
234 if (cred
->session_keyring
)
235 flags
= KEY_ALLOC_IN_QUOTA
;
237 keyring
= keyring_alloc("_ses", cred
->uid
, cred
->gid
, cred
,
238 KEY_POS_ALL
| KEY_USR_VIEW
| KEY_USR_READ
,
241 return PTR_ERR(keyring
);
246 /* install the keyring */
247 old
= cred
->session_keyring
;
248 rcu_assign_pointer(cred
->session_keyring
, keyring
);
257 * Install a session keyring, discarding the old one. If a keyring is not
258 * supplied, an empty one is invented.
260 static int install_session_keyring(struct key
*keyring
)
265 new = prepare_creds();
269 ret
= install_session_keyring_to_cred(new, keyring
);
275 return commit_creds(new);
279 * Handle the fsuid changing.
281 void key_fsuid_changed(struct task_struct
*tsk
)
283 /* update the ownership of the thread keyring */
285 if (tsk
->cred
->thread_keyring
) {
286 down_write(&tsk
->cred
->thread_keyring
->sem
);
287 tsk
->cred
->thread_keyring
->uid
= tsk
->cred
->fsuid
;
288 up_write(&tsk
->cred
->thread_keyring
->sem
);
293 * Handle the fsgid changing.
295 void key_fsgid_changed(struct task_struct
*tsk
)
297 /* update the ownership of the thread keyring */
299 if (tsk
->cred
->thread_keyring
) {
300 down_write(&tsk
->cred
->thread_keyring
->sem
);
301 tsk
->cred
->thread_keyring
->gid
= tsk
->cred
->fsgid
;
302 up_write(&tsk
->cred
->thread_keyring
->sem
);
307 * Search the process keyrings attached to the supplied cred for the first
310 * The search criteria are the type and the match function. The description is
311 * given to the match function as a parameter, but doesn't otherwise influence
312 * the search. Typically the match function will compare the description
313 * parameter to the key's description.
315 * This can only search keyrings that grant Search permission to the supplied
316 * credentials. Keyrings linked to searched keyrings will also be searched if
317 * they grant Search permission too. Keys can only be found if they grant
318 * Search permission to the credentials.
320 * Returns a pointer to the key with the key usage count incremented if
321 * successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only
322 * matched negative keys.
324 * In the case of a successful return, the possession attribute is set on the
325 * returned key reference.
327 key_ref_t
search_my_process_keyrings(struct keyring_search_context
*ctx
)
329 key_ref_t key_ref
, ret
, err
;
331 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
332 * searchable, but we failed to find a key or we found a negative key;
333 * otherwise we want to return a sample error (probably -EACCES) if
334 * none of the keyrings were searchable
336 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
340 err
= ERR_PTR(-EAGAIN
);
342 /* search the thread keyring first */
343 if (ctx
->cred
->thread_keyring
) {
344 key_ref
= keyring_search_aux(
345 make_key_ref(ctx
->cred
->thread_keyring
, 1), ctx
);
346 if (!IS_ERR(key_ref
))
349 switch (PTR_ERR(key_ref
)) {
350 case -EAGAIN
: /* no key */
351 case -ENOKEY
: /* negative key */
360 /* search the process keyring second */
361 if (ctx
->cred
->process_keyring
) {
362 key_ref
= keyring_search_aux(
363 make_key_ref(ctx
->cred
->process_keyring
, 1), ctx
);
364 if (!IS_ERR(key_ref
))
367 switch (PTR_ERR(key_ref
)) {
368 case -EAGAIN
: /* no key */
371 case -ENOKEY
: /* negative key */
380 /* search the session keyring */
381 if (ctx
->cred
->session_keyring
) {
383 key_ref
= keyring_search_aux(
384 make_key_ref(rcu_dereference(ctx
->cred
->session_keyring
), 1),
388 if (!IS_ERR(key_ref
))
391 switch (PTR_ERR(key_ref
)) {
392 case -EAGAIN
: /* no key */
395 case -ENOKEY
: /* negative key */
403 /* or search the user-session keyring */
404 else if (ctx
->cred
->user
->session_keyring
) {
405 key_ref
= keyring_search_aux(
406 make_key_ref(ctx
->cred
->user
->session_keyring
, 1),
408 if (!IS_ERR(key_ref
))
411 switch (PTR_ERR(key_ref
)) {
412 case -EAGAIN
: /* no key */
415 case -ENOKEY
: /* negative key */
424 /* no key - decide on the error we're going to go for */
425 key_ref
= ret
? ret
: err
;
432 * Search the process keyrings attached to the supplied cred for the first
433 * matching key in the manner of search_my_process_keyrings(), but also search
434 * the keys attached to the assumed authorisation key using its credentials if
437 * Return same as search_my_process_keyrings().
439 key_ref_t
search_process_keyrings(struct keyring_search_context
*ctx
)
441 struct request_key_auth
*rka
;
442 key_ref_t key_ref
, ret
= ERR_PTR(-EACCES
), err
;
446 key_ref
= search_my_process_keyrings(ctx
);
447 if (!IS_ERR(key_ref
))
451 /* if this process has an instantiation authorisation key, then we also
452 * search the keyrings of the process mentioned there
453 * - we don't permit access to request_key auth keys via this method
455 if (ctx
->cred
->request_key_auth
&&
456 ctx
->cred
== current_cred() &&
457 ctx
->index_key
.type
!= &key_type_request_key_auth
459 const struct cred
*cred
= ctx
->cred
;
461 /* defend against the auth key being revoked */
462 down_read(&cred
->request_key_auth
->sem
);
464 if (key_validate(ctx
->cred
->request_key_auth
) == 0) {
465 rka
= ctx
->cred
->request_key_auth
->payload
.data
[0];
467 ctx
->cred
= rka
->cred
;
468 key_ref
= search_process_keyrings(ctx
);
471 up_read(&cred
->request_key_auth
->sem
);
473 if (!IS_ERR(key_ref
))
478 up_read(&cred
->request_key_auth
->sem
);
482 /* no key - decide on the error we're going to go for */
483 if (err
== ERR_PTR(-ENOKEY
) || ret
== ERR_PTR(-ENOKEY
))
484 key_ref
= ERR_PTR(-ENOKEY
);
485 else if (err
== ERR_PTR(-EACCES
))
495 * See if the key we're looking at is the target key.
497 bool lookup_user_key_possessed(const struct key
*key
,
498 const struct key_match_data
*match_data
)
500 return key
== match_data
->raw_data
;
504 * Look up a key ID given us by userspace with a given permissions mask to get
505 * the key it refers to.
507 * Flags can be passed to request that special keyrings be created if referred
508 * to directly, to permit partially constructed keys to be found and to skip
509 * validity and permission checks on the found key.
511 * Returns a pointer to the key with an incremented usage count if successful;
512 * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond
513 * to a key or the best found key was a negative key; -EKEYREVOKED or
514 * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the
515 * found key doesn't grant the requested permit or the LSM denied access to it;
516 * or -ENOMEM if a special keyring couldn't be created.
518 * In the case of a successful return, the possession attribute is set on the
519 * returned key reference.
521 key_ref_t
lookup_user_key(key_serial_t id
, unsigned long lflags
,
524 struct keyring_search_context ctx
= {
525 .match_data
.cmp
= lookup_user_key_possessed
,
526 .match_data
.lookup_type
= KEYRING_SEARCH_LOOKUP_DIRECT
,
527 .flags
= KEYRING_SEARCH_NO_STATE_CHECK
,
529 struct request_key_auth
*rka
;
531 key_ref_t key_ref
, skey_ref
;
535 ctx
.cred
= get_current_cred();
536 key_ref
= ERR_PTR(-ENOKEY
);
539 case KEY_SPEC_THREAD_KEYRING
:
540 if (!ctx
.cred
->thread_keyring
) {
541 if (!(lflags
& KEY_LOOKUP_CREATE
))
544 ret
= install_thread_keyring();
546 key_ref
= ERR_PTR(ret
);
552 key
= ctx
.cred
->thread_keyring
;
554 key_ref
= make_key_ref(key
, 1);
557 case KEY_SPEC_PROCESS_KEYRING
:
558 if (!ctx
.cred
->process_keyring
) {
559 if (!(lflags
& KEY_LOOKUP_CREATE
))
562 ret
= install_process_keyring();
564 key_ref
= ERR_PTR(ret
);
570 key
= ctx
.cred
->process_keyring
;
572 key_ref
= make_key_ref(key
, 1);
575 case KEY_SPEC_SESSION_KEYRING
:
576 if (!ctx
.cred
->session_keyring
) {
577 /* always install a session keyring upon access if one
578 * doesn't exist yet */
579 ret
= install_user_keyrings();
582 if (lflags
& KEY_LOOKUP_CREATE
)
583 ret
= join_session_keyring(NULL
);
585 ret
= install_session_keyring(
586 ctx
.cred
->user
->session_keyring
);
591 } else if (ctx
.cred
->session_keyring
==
592 ctx
.cred
->user
->session_keyring
&&
593 lflags
& KEY_LOOKUP_CREATE
) {
594 ret
= join_session_keyring(NULL
);
601 key
= rcu_dereference(ctx
.cred
->session_keyring
);
604 key_ref
= make_key_ref(key
, 1);
607 case KEY_SPEC_USER_KEYRING
:
608 if (!ctx
.cred
->user
->uid_keyring
) {
609 ret
= install_user_keyrings();
614 key
= ctx
.cred
->user
->uid_keyring
;
616 key_ref
= make_key_ref(key
, 1);
619 case KEY_SPEC_USER_SESSION_KEYRING
:
620 if (!ctx
.cred
->user
->session_keyring
) {
621 ret
= install_user_keyrings();
626 key
= ctx
.cred
->user
->session_keyring
;
628 key_ref
= make_key_ref(key
, 1);
631 case KEY_SPEC_GROUP_KEYRING
:
632 /* group keyrings are not yet supported */
633 key_ref
= ERR_PTR(-EINVAL
);
636 case KEY_SPEC_REQKEY_AUTH_KEY
:
637 key
= ctx
.cred
->request_key_auth
;
642 key_ref
= make_key_ref(key
, 1);
645 case KEY_SPEC_REQUESTOR_KEYRING
:
646 if (!ctx
.cred
->request_key_auth
)
649 down_read(&ctx
.cred
->request_key_auth
->sem
);
650 if (test_bit(KEY_FLAG_REVOKED
,
651 &ctx
.cred
->request_key_auth
->flags
)) {
652 key_ref
= ERR_PTR(-EKEYREVOKED
);
655 rka
= ctx
.cred
->request_key_auth
->payload
.data
[0];
656 key
= rka
->dest_keyring
;
659 up_read(&ctx
.cred
->request_key_auth
->sem
);
662 key_ref
= make_key_ref(key
, 1);
666 key_ref
= ERR_PTR(-EINVAL
);
670 key
= key_lookup(id
);
672 key_ref
= ERR_CAST(key
);
676 key_ref
= make_key_ref(key
, 0);
678 /* check to see if we possess the key */
679 ctx
.index_key
.type
= key
->type
;
680 ctx
.index_key
.description
= key
->description
;
681 ctx
.index_key
.desc_len
= strlen(key
->description
);
682 ctx
.match_data
.raw_data
= key
;
683 kdebug("check possessed");
684 skey_ref
= search_process_keyrings(&ctx
);
685 kdebug("possessed=%p", skey_ref
);
687 if (!IS_ERR(skey_ref
)) {
695 /* unlink does not use the nominated key in any way, so can skip all
696 * the permission checks as it is only concerned with the keyring */
697 if (lflags
& KEY_LOOKUP_FOR_UNLINK
) {
702 if (!(lflags
& KEY_LOOKUP_PARTIAL
)) {
703 ret
= wait_for_key_construction(key
, true);
714 ret
= key_validate(key
);
720 if (!(lflags
& KEY_LOOKUP_PARTIAL
) &&
721 !test_bit(KEY_FLAG_INSTANTIATED
, &key
->flags
))
724 /* check the permissions */
725 ret
= key_task_permission(key_ref
, ctx
.cred
, perm
);
729 key
->last_used_at
= current_kernel_time().tv_sec
;
736 key_ref_put(key_ref
);
737 key_ref
= ERR_PTR(ret
);
740 /* if we attempted to install a keyring, then it may have caused new
741 * creds to be installed */
748 * Join the named keyring as the session keyring if possible else attempt to
749 * create a new one of that name and join that.
751 * If the name is NULL, an empty anonymous keyring will be installed as the
754 * Named session keyrings are joined with a semaphore held to prevent the
755 * keyrings from going away whilst the attempt is made to going them and also
756 * to prevent a race in creating compatible session keyrings.
758 long join_session_keyring(const char *name
)
760 const struct cred
*old
;
765 new = prepare_creds();
768 old
= current_cred();
770 /* if no name is provided, install an anonymous keyring */
772 ret
= install_session_keyring_to_cred(new, NULL
);
776 serial
= new->session_keyring
->serial
;
777 ret
= commit_creds(new);
783 /* allow the user to join or create a named keyring */
784 mutex_lock(&key_session_mutex
);
786 /* look for an existing keyring of this name */
787 keyring
= find_keyring_by_name(name
, false);
788 if (PTR_ERR(keyring
) == -ENOKEY
) {
789 /* not found - try and create a new one */
790 keyring
= keyring_alloc(
791 name
, old
->uid
, old
->gid
, old
,
792 KEY_POS_ALL
| KEY_USR_VIEW
| KEY_USR_READ
| KEY_USR_LINK
,
793 KEY_ALLOC_IN_QUOTA
, NULL
, NULL
);
794 if (IS_ERR(keyring
)) {
795 ret
= PTR_ERR(keyring
);
798 } else if (IS_ERR(keyring
)) {
799 ret
= PTR_ERR(keyring
);
801 } else if (keyring
== new->session_keyring
) {
807 /* we've got a keyring - now to install it */
808 ret
= install_session_keyring_to_cred(new, keyring
);
813 mutex_unlock(&key_session_mutex
);
815 ret
= keyring
->serial
;
821 mutex_unlock(&key_session_mutex
);
828 * Replace a process's session keyring on behalf of one of its children when
829 * the target process is about to resume userspace execution.
831 void key_change_session_keyring(struct callback_head
*twork
)
833 const struct cred
*old
= current_cred();
834 struct cred
*new = container_of(twork
, struct cred
, rcu
);
836 if (unlikely(current
->flags
& PF_EXITING
)) {
841 new-> uid
= old
-> uid
;
842 new-> euid
= old
-> euid
;
843 new-> suid
= old
-> suid
;
844 new->fsuid
= old
->fsuid
;
845 new-> gid
= old
-> gid
;
846 new-> egid
= old
-> egid
;
847 new-> sgid
= old
-> sgid
;
848 new->fsgid
= old
->fsgid
;
849 new->user
= get_uid(old
->user
);
850 new->user_ns
= get_user_ns(old
->user_ns
);
851 new->group_info
= get_group_info(old
->group_info
);
853 new->securebits
= old
->securebits
;
854 new->cap_inheritable
= old
->cap_inheritable
;
855 new->cap_permitted
= old
->cap_permitted
;
856 new->cap_effective
= old
->cap_effective
;
857 new->cap_ambient
= old
->cap_ambient
;
858 new->cap_bset
= old
->cap_bset
;
860 new->jit_keyring
= old
->jit_keyring
;
861 new->thread_keyring
= key_get(old
->thread_keyring
);
862 new->process_keyring
= key_get(old
->process_keyring
);
864 security_transfer_creds(new, old
);
870 * Make sure that root's user and user-session keyrings exist.
872 static int __init
init_root_keyring(void)
874 return install_user_keyrings();
877 late_initcall(init_root_keyring
);