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>
13 #include <linux/security.h>
17 * key_task_permission - Check a key can be used
18 * @key_ref: The key to check
19 * @cred: The credentials to use
20 * @perm: The permissions to check for
22 * Check to see whether permission is granted to use a key in the desired way,
23 * but permit the security modules to override.
25 * The caller must hold either a ref on cred or must hold the RCU readlock or a
28 int key_task_permission(const key_ref_t key_ref, const struct cred *cred,
35 key = key_ref_to_ptr(key_ref);
37 if (key->user->user_ns != cred->user->user_ns)
40 /* use the second 8-bits of permissions for keys the caller owns */
41 if (key->uid == cred->fsuid) {
42 kperm = key->perm >> 16;
46 /* use the third 8-bits of permissions for keys the caller has a group
47 * membership in common with */
48 if (key->gid != -1 && key->perm & KEY_GRP_ALL) {
49 if (key->gid == cred->fsgid) {
50 kperm = key->perm >> 8;
54 ret = groups_search(cred->group_info, key->gid);
56 kperm = key->perm >> 8;
63 /* otherwise use the least-significant 8-bits */
68 /* use the top 8-bits of permissions for keys the caller possesses
69 * - possessor permissions are additive with other permissions
71 if (is_key_possessed(key_ref))
72 kperm |= key->perm >> 24;
74 kperm = kperm & perm & KEY_ALL;
79 /* let LSM be the final arbiter */
80 return security_key_permission(key_ref, cred, perm);
83 EXPORT_SYMBOL(key_task_permission);
88 int key_validate(struct key *key)
94 /* check it's still accessible */
96 if (test_bit(KEY_FLAG_REVOKED, &key->flags) ||
97 test_bit(KEY_FLAG_DEAD, &key->flags))
100 /* check it hasn't expired */
103 now = current_kernel_time();
104 if (now.tv_sec >= key->expiry)
113 EXPORT_SYMBOL(key_validate);