1 /* permission.c: key permission determination
3 * Copyright (C) 2005 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>
15 /*****************************************************************************/
17 * check to see whether permission is granted to use a key in the desired way,
18 * but permit the security modules to override
20 int key_task_permission(const key_ref_t key_ref
,
21 struct task_struct
*context
,
28 key
= key_ref_to_ptr(key_ref
);
30 /* use the second 8-bits of permissions for keys the caller owns */
31 if (key
->uid
== context
->fsuid
) {
32 kperm
= key
->perm
>> 16;
36 /* use the third 8-bits of permissions for keys the caller has a group
37 * membership in common with */
38 if (key
->gid
!= -1 && key
->perm
& KEY_GRP_ALL
) {
39 if (key
->gid
== context
->fsgid
) {
40 kperm
= key
->perm
>> 8;
45 ret
= groups_search(context
->group_info
, key
->gid
);
49 kperm
= key
->perm
>> 8;
54 /* otherwise use the least-significant 8-bits */
58 /* use the top 8-bits of permissions for keys the caller possesses
59 * - possessor permissions are additive with other permissions
61 if (is_key_possessed(key_ref
))
62 kperm
|= key
->perm
>> 24;
64 kperm
= kperm
& perm
& KEY_ALL
;
68 } /* end key_task_permission() */
70 EXPORT_SYMBOL(key_task_permission
);