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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 | /*****************************************************************************/ | |
17 | /* | |
18 | * check to see whether permission is granted to use a key in the desired way, | |
19 | * but permit the security modules to override | |
20 | */ | |
21 | int key_task_permission(const key_ref_t key_ref, | |
22 | struct task_struct *context, | |
23 | key_perm_t perm) | |
24 | { | |
25 | struct key *key; | |
26 | key_perm_t kperm; | |
27 | int ret; | |
28 | ||
29 | key = key_ref_to_ptr(key_ref); | |
30 | ||
468ed2b0 DH |
31 | /* use the second 8-bits of permissions for keys the caller owns */ |
32 | if (key->uid == context->fsuid) { | |
33 | kperm = key->perm >> 16; | |
34 | goto use_these_perms; | |
35 | } | |
36 | ||
37 | /* use the third 8-bits of permissions for keys the caller has a group | |
38 | * membership in common with */ | |
39 | if (key->gid != -1 && key->perm & KEY_GRP_ALL) { | |
40 | if (key->gid == context->fsgid) { | |
41 | kperm = key->perm >> 8; | |
42 | goto use_these_perms; | |
43 | } | |
44 | ||
45 | task_lock(context); | |
46 | ret = groups_search(context->group_info, key->gid); | |
47 | task_unlock(context); | |
48 | ||
49 | if (ret) { | |
50 | kperm = key->perm >> 8; | |
51 | goto use_these_perms; | |
52 | } | |
53 | } | |
54 | ||
55 | /* otherwise use the least-significant 8-bits */ | |
56 | kperm = key->perm; | |
57 | ||
58 | use_these_perms: | |
7ab501db DH |
59 | /* use the top 8-bits of permissions for keys the caller possesses |
60 | * - possessor permissions are additive with other permissions | |
61 | */ | |
62 | if (is_key_possessed(key_ref)) | |
63 | kperm |= key->perm >> 24; | |
64 | ||
468ed2b0 DH |
65 | kperm = kperm & perm & KEY_ALL; |
66 | ||
29db9190 DH |
67 | if (kperm != perm) |
68 | return -EACCES; | |
69 | ||
70 | /* let LSM be the final arbiter */ | |
71 | return security_key_permission(key_ref, context, perm); | |
468ed2b0 DH |
72 | |
73 | } /* end key_task_permission() */ | |
74 | ||
75 | EXPORT_SYMBOL(key_task_permission); | |
b5f545c8 DH |
76 | |
77 | /*****************************************************************************/ | |
78 | /* | |
79 | * validate a key | |
80 | */ | |
81 | int key_validate(struct key *key) | |
82 | { | |
83 | struct timespec now; | |
84 | int ret = 0; | |
85 | ||
86 | if (key) { | |
87 | /* check it's still accessible */ | |
88 | ret = -EKEYREVOKED; | |
89 | if (test_bit(KEY_FLAG_REVOKED, &key->flags) || | |
90 | test_bit(KEY_FLAG_DEAD, &key->flags)) | |
91 | goto error; | |
92 | ||
93 | /* check it hasn't expired */ | |
94 | ret = 0; | |
95 | if (key->expiry) { | |
96 | now = current_kernel_time(); | |
97 | if (now.tv_sec >= key->expiry) | |
98 | ret = -EKEYEXPIRED; | |
99 | } | |
100 | } | |
101 | ||
102 | error: | |
103 | return ret; | |
104 | ||
105 | } /* end key_validate() */ | |
106 | ||
107 | EXPORT_SYMBOL(key_validate); |