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468ed2b0 DH |
1 | /* permission.c: key permission determination |
2 | * | |
3 | * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved. | |
4 | * Written by David Howells (dhowells@redhat.com) | |
5 | * | |
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. | |
10 | */ | |
11 | ||
12 | #include <linux/module.h> | |
29db9190 | 13 | #include <linux/security.h> |
468ed2b0 DH |
14 | #include "internal.h" |
15 | ||
16 | /*****************************************************************************/ | |
d84f4f99 DH |
17 | /** |
18 | * key_task_permission - Check a key can be used | |
19 | * @key_ref: The key to check | |
20 | * @cred: The credentials to use | |
21 | * @perm: The permissions to check for | |
22 | * | |
23 | * Check to see whether permission is granted to use a key in the desired way, | |
24 | * but permit the security modules to override. | |
25 | * | |
26 | * The caller must hold either a ref on cred or must hold the RCU readlock or a | |
27 | * spinlock. | |
468ed2b0 | 28 | */ |
d84f4f99 | 29 | int key_task_permission(const key_ref_t key_ref, const struct cred *cred, |
468ed2b0 DH |
30 | key_perm_t perm) |
31 | { | |
32 | struct key *key; | |
33 | key_perm_t kperm; | |
34 | int ret; | |
35 | ||
36 | key = key_ref_to_ptr(key_ref); | |
37 | ||
468ed2b0 | 38 | /* use the second 8-bits of permissions for keys the caller owns */ |
b6dff3ec | 39 | if (key->uid == cred->fsuid) { |
468ed2b0 DH |
40 | kperm = key->perm >> 16; |
41 | goto use_these_perms; | |
42 | } | |
43 | ||
44 | /* use the third 8-bits of permissions for keys the caller has a group | |
45 | * membership in common with */ | |
46 | if (key->gid != -1 && key->perm & KEY_GRP_ALL) { | |
b6dff3ec | 47 | if (key->gid == cred->fsgid) { |
468ed2b0 DH |
48 | kperm = key->perm >> 8; |
49 | goto use_these_perms; | |
50 | } | |
51 | ||
b6dff3ec | 52 | ret = groups_search(cred->group_info, key->gid); |
468ed2b0 DH |
53 | if (ret) { |
54 | kperm = key->perm >> 8; | |
55 | goto use_these_perms; | |
56 | } | |
57 | } | |
58 | ||
59 | /* otherwise use the least-significant 8-bits */ | |
60 | kperm = key->perm; | |
61 | ||
62 | use_these_perms: | |
c69e8d9c | 63 | |
7ab501db DH |
64 | /* use the top 8-bits of permissions for keys the caller possesses |
65 | * - possessor permissions are additive with other permissions | |
66 | */ | |
67 | if (is_key_possessed(key_ref)) | |
68 | kperm |= key->perm >> 24; | |
69 | ||
468ed2b0 DH |
70 | kperm = kperm & perm & KEY_ALL; |
71 | ||
29db9190 DH |
72 | if (kperm != perm) |
73 | return -EACCES; | |
74 | ||
75 | /* let LSM be the final arbiter */ | |
d84f4f99 | 76 | return security_key_permission(key_ref, cred, perm); |
468ed2b0 DH |
77 | |
78 | } /* end key_task_permission() */ | |
79 | ||
80 | EXPORT_SYMBOL(key_task_permission); | |
b5f545c8 DH |
81 | |
82 | /*****************************************************************************/ | |
83 | /* | |
84 | * validate a key | |
85 | */ | |
86 | int key_validate(struct key *key) | |
87 | { | |
88 | struct timespec now; | |
89 | int ret = 0; | |
90 | ||
91 | if (key) { | |
92 | /* check it's still accessible */ | |
93 | ret = -EKEYREVOKED; | |
94 | if (test_bit(KEY_FLAG_REVOKED, &key->flags) || | |
95 | test_bit(KEY_FLAG_DEAD, &key->flags)) | |
96 | goto error; | |
97 | ||
98 | /* check it hasn't expired */ | |
99 | ret = 0; | |
100 | if (key->expiry) { | |
101 | now = current_kernel_time(); | |
102 | if (now.tv_sec >= key->expiry) | |
103 | ret = -EKEYEXPIRED; | |
104 | } | |
105 | } | |
106 | ||
107 | error: | |
108 | return ret; | |
109 | ||
110 | } /* end key_validate() */ | |
111 | ||
112 | EXPORT_SYMBOL(key_validate); |