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/keyctl.h>
17 #include <linux/err.h>
18 #include <linux/mutex.h>
19 #include <linux/security.h>
20 #include <linux/user_namespace.h>
21 #include <linux/uaccess.h>
24 /* Session keyring create vs join semaphore */
25 static DEFINE_MUTEX(key_session_mutex
);
27 /* User keyring creation semaphore */
28 static DEFINE_MUTEX(key_user_keyring_mutex
);
30 /* The root user's tracking struct */
31 struct key_user root_key_user
= {
32 .usage
= ATOMIC_INIT(3),
33 .cons_lock
= __MUTEX_INITIALIZER(root_key_user
.cons_lock
),
34 .lock
= __SPIN_LOCK_UNLOCKED(root_key_user
.lock
),
35 .nkeys
= ATOMIC_INIT(2),
36 .nikeys
= ATOMIC_INIT(2),
37 .uid
= GLOBAL_ROOT_UID
,
41 * Install the user and user session keyrings for the current process's UID.
43 int install_user_keyrings(void)
45 struct user_struct
*user
;
46 const struct cred
*cred
;
47 struct key
*uid_keyring
, *session_keyring
;
48 key_perm_t user_keyring_perm
;
53 user_keyring_perm
= (KEY_POS_ALL
& ~KEY_POS_SETATTR
) | KEY_USR_ALL
;
54 cred
= current_cred();
56 uid
= from_kuid(cred
->user_ns
, user
->uid
);
58 kenter("%p{%u}", user
, uid
);
60 if (user
->uid_keyring
&& user
->session_keyring
) {
61 kleave(" = 0 [exist]");
65 mutex_lock(&key_user_keyring_mutex
);
68 if (!user
->uid_keyring
) {
69 /* get the UID-specific keyring
70 * - there may be one in existence already as it may have been
71 * pinned by a session, but the user_struct pointing to it
72 * may have been destroyed by setuid */
73 sprintf(buf
, "_uid.%u", uid
);
75 uid_keyring
= find_keyring_by_name(buf
, true);
76 if (IS_ERR(uid_keyring
)) {
77 uid_keyring
= keyring_alloc(buf
, user
->uid
, INVALID_GID
,
78 cred
, user_keyring_perm
,
81 if (IS_ERR(uid_keyring
)) {
82 ret
= PTR_ERR(uid_keyring
);
87 /* get a default session keyring (which might also exist
89 sprintf(buf
, "_uid_ses.%u", uid
);
91 session_keyring
= find_keyring_by_name(buf
, true);
92 if (IS_ERR(session_keyring
)) {
94 keyring_alloc(buf
, user
->uid
, INVALID_GID
,
95 cred
, user_keyring_perm
,
98 if (IS_ERR(session_keyring
)) {
99 ret
= PTR_ERR(session_keyring
);
103 /* we install a link from the user session keyring to
104 * the user keyring */
105 ret
= key_link(session_keyring
, uid_keyring
);
107 goto error_release_both
;
110 /* install the keyrings */
111 user
->uid_keyring
= uid_keyring
;
112 user
->session_keyring
= session_keyring
;
115 mutex_unlock(&key_user_keyring_mutex
);
120 key_put(session_keyring
);
122 key_put(uid_keyring
);
124 mutex_unlock(&key_user_keyring_mutex
);
125 kleave(" = %d", ret
);
130 * Install a fresh thread keyring directly to new credentials. This keyring is
131 * allowed to overrun the quota.
133 int install_thread_keyring_to_cred(struct cred
*new)
137 keyring
= keyring_alloc("_tid", new->uid
, new->gid
, new,
138 KEY_POS_ALL
| KEY_USR_VIEW
,
139 KEY_ALLOC_QUOTA_OVERRUN
,
142 return PTR_ERR(keyring
);
144 new->thread_keyring
= keyring
;
149 * Install a fresh thread keyring, discarding the old one.
151 static int install_thread_keyring(void)
156 new = prepare_creds();
160 BUG_ON(new->thread_keyring
);
162 ret
= install_thread_keyring_to_cred(new);
168 return commit_creds(new);
172 * Install a process keyring directly to a credentials struct.
174 * Returns -EEXIST if there was already a process keyring, 0 if one installed,
175 * and other value on any other error
177 int install_process_keyring_to_cred(struct cred
*new)
181 if (new->process_keyring
)
184 keyring
= keyring_alloc("_pid", new->uid
, new->gid
, new,
185 KEY_POS_ALL
| KEY_USR_VIEW
,
186 KEY_ALLOC_QUOTA_OVERRUN
,
189 return PTR_ERR(keyring
);
191 new->process_keyring
= keyring
;
196 * Make sure a process keyring is installed for the current process. The
197 * existing process keyring is not replaced.
199 * Returns 0 if there is a process keyring by the end of this function, some
202 static int install_process_keyring(void)
207 new = prepare_creds();
211 ret
= install_process_keyring_to_cred(new);
214 return ret
!= -EEXIST
? ret
: 0;
217 return commit_creds(new);
221 * Install a session keyring directly to a credentials struct.
223 int install_session_keyring_to_cred(struct cred
*cred
, struct key
*keyring
)
230 /* create an empty session keyring */
232 flags
= KEY_ALLOC_QUOTA_OVERRUN
;
233 if (cred
->session_keyring
)
234 flags
= KEY_ALLOC_IN_QUOTA
;
236 keyring
= keyring_alloc("_ses", cred
->uid
, cred
->gid
, cred
,
237 KEY_POS_ALL
| KEY_USR_VIEW
| KEY_USR_READ
,
240 return PTR_ERR(keyring
);
245 /* install the keyring */
246 old
= cred
->session_keyring
;
247 rcu_assign_pointer(cred
->session_keyring
, keyring
);
256 * Install a session keyring, discarding the old one. If a keyring is not
257 * supplied, an empty one is invented.
259 static int install_session_keyring(struct key
*keyring
)
264 new = prepare_creds();
268 ret
= install_session_keyring_to_cred(new, keyring
);
274 return commit_creds(new);
278 * Handle the fsuid changing.
280 void key_fsuid_changed(struct task_struct
*tsk
)
282 /* update the ownership of the thread keyring */
284 if (tsk
->cred
->thread_keyring
) {
285 down_write(&tsk
->cred
->thread_keyring
->sem
);
286 tsk
->cred
->thread_keyring
->uid
= tsk
->cred
->fsuid
;
287 up_write(&tsk
->cred
->thread_keyring
->sem
);
292 * Handle the fsgid changing.
294 void key_fsgid_changed(struct task_struct
*tsk
)
296 /* update the ownership of the thread keyring */
298 if (tsk
->cred
->thread_keyring
) {
299 down_write(&tsk
->cred
->thread_keyring
->sem
);
300 tsk
->cred
->thread_keyring
->gid
= tsk
->cred
->fsgid
;
301 up_write(&tsk
->cred
->thread_keyring
->sem
);
306 * Search the process keyrings attached to the supplied cred for the first
309 * The search criteria are the type and the match function. The description is
310 * given to the match function as a parameter, but doesn't otherwise influence
311 * the search. Typically the match function will compare the description
312 * parameter to the key's description.
314 * This can only search keyrings that grant Search permission to the supplied
315 * credentials. Keyrings linked to searched keyrings will also be searched if
316 * they grant Search permission too. Keys can only be found if they grant
317 * Search permission to the credentials.
319 * Returns a pointer to the key with the key usage count incremented if
320 * successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only
321 * matched negative keys.
323 * In the case of a successful return, the possession attribute is set on the
324 * returned key reference.
326 key_ref_t
search_my_process_keyrings(struct keyring_search_context
*ctx
)
328 key_ref_t key_ref
, ret
, err
;
330 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
331 * searchable, but we failed to find a key or we found a negative key;
332 * otherwise we want to return a sample error (probably -EACCES) if
333 * none of the keyrings were searchable
335 * in terms of priority: success > -ENOKEY > -EAGAIN > other error
339 err
= ERR_PTR(-EAGAIN
);
341 /* search the thread keyring first */
342 if (ctx
->cred
->thread_keyring
) {
343 key_ref
= keyring_search_aux(
344 make_key_ref(ctx
->cred
->thread_keyring
, 1), ctx
);
345 if (!IS_ERR(key_ref
))
348 switch (PTR_ERR(key_ref
)) {
349 case -EAGAIN
: /* no key */
350 case -ENOKEY
: /* negative key */
359 /* search the process keyring second */
360 if (ctx
->cred
->process_keyring
) {
361 key_ref
= keyring_search_aux(
362 make_key_ref(ctx
->cred
->process_keyring
, 1), ctx
);
363 if (!IS_ERR(key_ref
))
366 switch (PTR_ERR(key_ref
)) {
367 case -EAGAIN
: /* no key */
370 case -ENOKEY
: /* negative key */
379 /* search the session keyring */
380 if (ctx
->cred
->session_keyring
) {
382 key_ref
= keyring_search_aux(
383 make_key_ref(rcu_dereference(ctx
->cred
->session_keyring
), 1),
387 if (!IS_ERR(key_ref
))
390 switch (PTR_ERR(key_ref
)) {
391 case -EAGAIN
: /* no key */
394 case -ENOKEY
: /* negative key */
402 /* or search the user-session keyring */
403 else if (ctx
->cred
->user
->session_keyring
) {
404 key_ref
= keyring_search_aux(
405 make_key_ref(ctx
->cred
->user
->session_keyring
, 1),
407 if (!IS_ERR(key_ref
))
410 switch (PTR_ERR(key_ref
)) {
411 case -EAGAIN
: /* no key */
414 case -ENOKEY
: /* negative key */
423 /* no key - decide on the error we're going to go for */
424 key_ref
= ret
? ret
: err
;
431 * Search the process keyrings attached to the supplied cred for the first
432 * matching key in the manner of search_my_process_keyrings(), but also search
433 * the keys attached to the assumed authorisation key using its credentials if
436 * Return same as search_my_process_keyrings().
438 key_ref_t
search_process_keyrings(struct keyring_search_context
*ctx
)
440 struct request_key_auth
*rka
;
441 key_ref_t key_ref
, ret
= ERR_PTR(-EACCES
), err
;
445 key_ref
= search_my_process_keyrings(ctx
);
446 if (!IS_ERR(key_ref
))
450 /* if this process has an instantiation authorisation key, then we also
451 * search the keyrings of the process mentioned there
452 * - we don't permit access to request_key auth keys via this method
454 if (ctx
->cred
->request_key_auth
&&
455 ctx
->cred
== current_cred() &&
456 ctx
->index_key
.type
!= &key_type_request_key_auth
458 const struct cred
*cred
= ctx
->cred
;
460 /* defend against the auth key being revoked */
461 down_read(&cred
->request_key_auth
->sem
);
463 if (key_validate(ctx
->cred
->request_key_auth
) == 0) {
464 rka
= ctx
->cred
->request_key_auth
->payload
.data
[0];
466 ctx
->cred
= rka
->cred
;
467 key_ref
= search_process_keyrings(ctx
);
470 up_read(&cred
->request_key_auth
->sem
);
472 if (!IS_ERR(key_ref
))
477 up_read(&cred
->request_key_auth
->sem
);
481 /* no key - decide on the error we're going to go for */
482 if (err
== ERR_PTR(-ENOKEY
) || ret
== ERR_PTR(-ENOKEY
))
483 key_ref
= ERR_PTR(-ENOKEY
);
484 else if (err
== ERR_PTR(-EACCES
))
494 * See if the key we're looking at is the target key.
496 bool lookup_user_key_possessed(const struct key
*key
,
497 const struct key_match_data
*match_data
)
499 return key
== match_data
->raw_data
;
503 * Look up a key ID given us by userspace with a given permissions mask to get
504 * the key it refers to.
506 * Flags can be passed to request that special keyrings be created if referred
507 * to directly, to permit partially constructed keys to be found and to skip
508 * validity and permission checks on the found key.
510 * Returns a pointer to the key with an incremented usage count if successful;
511 * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond
512 * to a key or the best found key was a negative key; -EKEYREVOKED or
513 * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the
514 * found key doesn't grant the requested permit or the LSM denied access to it;
515 * or -ENOMEM if a special keyring couldn't be created.
517 * In the case of a successful return, the possession attribute is set on the
518 * returned key reference.
520 key_ref_t
lookup_user_key(key_serial_t id
, unsigned long lflags
,
523 struct keyring_search_context ctx
= {
524 .match_data
.cmp
= lookup_user_key_possessed
,
525 .match_data
.lookup_type
= KEYRING_SEARCH_LOOKUP_DIRECT
,
526 .flags
= KEYRING_SEARCH_NO_STATE_CHECK
,
528 struct request_key_auth
*rka
;
530 key_ref_t key_ref
, skey_ref
;
534 ctx
.cred
= get_current_cred();
535 key_ref
= ERR_PTR(-ENOKEY
);
538 case KEY_SPEC_THREAD_KEYRING
:
539 if (!ctx
.cred
->thread_keyring
) {
540 if (!(lflags
& KEY_LOOKUP_CREATE
))
543 ret
= install_thread_keyring();
545 key_ref
= ERR_PTR(ret
);
551 key
= ctx
.cred
->thread_keyring
;
553 key_ref
= make_key_ref(key
, 1);
556 case KEY_SPEC_PROCESS_KEYRING
:
557 if (!ctx
.cred
->process_keyring
) {
558 if (!(lflags
& KEY_LOOKUP_CREATE
))
561 ret
= install_process_keyring();
563 key_ref
= ERR_PTR(ret
);
569 key
= ctx
.cred
->process_keyring
;
571 key_ref
= make_key_ref(key
, 1);
574 case KEY_SPEC_SESSION_KEYRING
:
575 if (!ctx
.cred
->session_keyring
) {
576 /* always install a session keyring upon access if one
577 * doesn't exist yet */
578 ret
= install_user_keyrings();
581 if (lflags
& KEY_LOOKUP_CREATE
)
582 ret
= join_session_keyring(NULL
);
584 ret
= install_session_keyring(
585 ctx
.cred
->user
->session_keyring
);
590 } else if (ctx
.cred
->session_keyring
==
591 ctx
.cred
->user
->session_keyring
&&
592 lflags
& KEY_LOOKUP_CREATE
) {
593 ret
= join_session_keyring(NULL
);
600 key
= rcu_dereference(ctx
.cred
->session_keyring
);
603 key_ref
= make_key_ref(key
, 1);
606 case KEY_SPEC_USER_KEYRING
:
607 if (!ctx
.cred
->user
->uid_keyring
) {
608 ret
= install_user_keyrings();
613 key
= ctx
.cred
->user
->uid_keyring
;
615 key_ref
= make_key_ref(key
, 1);
618 case KEY_SPEC_USER_SESSION_KEYRING
:
619 if (!ctx
.cred
->user
->session_keyring
) {
620 ret
= install_user_keyrings();
625 key
= ctx
.cred
->user
->session_keyring
;
627 key_ref
= make_key_ref(key
, 1);
630 case KEY_SPEC_GROUP_KEYRING
:
631 /* group keyrings are not yet supported */
632 key_ref
= ERR_PTR(-EINVAL
);
635 case KEY_SPEC_REQKEY_AUTH_KEY
:
636 key
= ctx
.cred
->request_key_auth
;
641 key_ref
= make_key_ref(key
, 1);
644 case KEY_SPEC_REQUESTOR_KEYRING
:
645 if (!ctx
.cred
->request_key_auth
)
648 down_read(&ctx
.cred
->request_key_auth
->sem
);
649 if (test_bit(KEY_FLAG_REVOKED
,
650 &ctx
.cred
->request_key_auth
->flags
)) {
651 key_ref
= ERR_PTR(-EKEYREVOKED
);
654 rka
= ctx
.cred
->request_key_auth
->payload
.data
[0];
655 key
= rka
->dest_keyring
;
658 up_read(&ctx
.cred
->request_key_auth
->sem
);
661 key_ref
= make_key_ref(key
, 1);
665 key_ref
= ERR_PTR(-EINVAL
);
669 key
= key_lookup(id
);
671 key_ref
= ERR_CAST(key
);
675 key_ref
= make_key_ref(key
, 0);
677 /* check to see if we possess the key */
678 ctx
.index_key
.type
= key
->type
;
679 ctx
.index_key
.description
= key
->description
;
680 ctx
.index_key
.desc_len
= strlen(key
->description
);
681 ctx
.match_data
.raw_data
= key
;
682 kdebug("check possessed");
683 skey_ref
= search_process_keyrings(&ctx
);
684 kdebug("possessed=%p", skey_ref
);
686 if (!IS_ERR(skey_ref
)) {
694 /* unlink does not use the nominated key in any way, so can skip all
695 * the permission checks as it is only concerned with the keyring */
696 if (lflags
& KEY_LOOKUP_FOR_UNLINK
) {
701 if (!(lflags
& KEY_LOOKUP_PARTIAL
)) {
702 ret
= wait_for_key_construction(key
, true);
713 ret
= key_validate(key
);
719 if (!(lflags
& KEY_LOOKUP_PARTIAL
) &&
720 !test_bit(KEY_FLAG_INSTANTIATED
, &key
->flags
))
723 /* check the permissions */
724 ret
= key_task_permission(key_ref
, ctx
.cred
, perm
);
728 key
->last_used_at
= current_kernel_time().tv_sec
;
735 key_ref_put(key_ref
);
736 key_ref
= ERR_PTR(ret
);
739 /* if we attempted to install a keyring, then it may have caused new
740 * creds to be installed */
747 * Join the named keyring as the session keyring if possible else attempt to
748 * create a new one of that name and join that.
750 * If the name is NULL, an empty anonymous keyring will be installed as the
753 * Named session keyrings are joined with a semaphore held to prevent the
754 * keyrings from going away whilst the attempt is made to going them and also
755 * to prevent a race in creating compatible session keyrings.
757 long join_session_keyring(const char *name
)
759 const struct cred
*old
;
764 new = prepare_creds();
767 old
= current_cred();
769 /* if no name is provided, install an anonymous keyring */
771 ret
= install_session_keyring_to_cred(new, NULL
);
775 serial
= new->session_keyring
->serial
;
776 ret
= commit_creds(new);
782 /* allow the user to join or create a named keyring */
783 mutex_lock(&key_session_mutex
);
785 /* look for an existing keyring of this name */
786 keyring
= find_keyring_by_name(name
, false);
787 if (PTR_ERR(keyring
) == -ENOKEY
) {
788 /* not found - try and create a new one */
789 keyring
= keyring_alloc(
790 name
, old
->uid
, old
->gid
, old
,
791 KEY_POS_ALL
| KEY_USR_VIEW
| KEY_USR_READ
| KEY_USR_LINK
,
792 KEY_ALLOC_IN_QUOTA
, NULL
, NULL
);
793 if (IS_ERR(keyring
)) {
794 ret
= PTR_ERR(keyring
);
797 } else if (IS_ERR(keyring
)) {
798 ret
= PTR_ERR(keyring
);
800 } else if (keyring
== new->session_keyring
) {
806 /* we've got a keyring - now to install it */
807 ret
= install_session_keyring_to_cred(new, keyring
);
812 mutex_unlock(&key_session_mutex
);
814 ret
= keyring
->serial
;
820 mutex_unlock(&key_session_mutex
);
827 * Replace a process's session keyring on behalf of one of its children when
828 * the target process is about to resume userspace execution.
830 void key_change_session_keyring(struct callback_head
*twork
)
832 const struct cred
*old
= current_cred();
833 struct cred
*new = container_of(twork
, struct cred
, rcu
);
835 if (unlikely(current
->flags
& PF_EXITING
)) {
840 new-> uid
= old
-> uid
;
841 new-> euid
= old
-> euid
;
842 new-> suid
= old
-> suid
;
843 new->fsuid
= old
->fsuid
;
844 new-> gid
= old
-> gid
;
845 new-> egid
= old
-> egid
;
846 new-> sgid
= old
-> sgid
;
847 new->fsgid
= old
->fsgid
;
848 new->user
= get_uid(old
->user
);
849 new->user_ns
= get_user_ns(old
->user_ns
);
850 new->group_info
= get_group_info(old
->group_info
);
852 new->securebits
= old
->securebits
;
853 new->cap_inheritable
= old
->cap_inheritable
;
854 new->cap_permitted
= old
->cap_permitted
;
855 new->cap_effective
= old
->cap_effective
;
856 new->cap_ambient
= old
->cap_ambient
;
857 new->cap_bset
= old
->cap_bset
;
859 new->jit_keyring
= old
->jit_keyring
;
860 new->thread_keyring
= key_get(old
->thread_keyring
);
861 new->process_keyring
= key_get(old
->process_keyring
);
863 security_transfer_creds(new, old
);
869 * Make sure that root's user and user-session keyrings exist.
871 static int __init
init_root_keyring(void)
873 return install_user_keyrings();
876 late_initcall(init_root_keyring
);