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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 | { | |
c69e8d9c | 25 | const struct cred *cred; |
468ed2b0 DH |
26 | struct key *key; |
27 | key_perm_t kperm; | |
28 | int ret; | |
29 | ||
30 | key = key_ref_to_ptr(key_ref); | |
31 | ||
c69e8d9c DH |
32 | rcu_read_lock(); |
33 | cred = __task_cred(context); | |
34 | ||
468ed2b0 | 35 | /* use the second 8-bits of permissions for keys the caller owns */ |
b6dff3ec | 36 | if (key->uid == cred->fsuid) { |
468ed2b0 DH |
37 | kperm = key->perm >> 16; |
38 | goto use_these_perms; | |
39 | } | |
40 | ||
41 | /* use the third 8-bits of permissions for keys the caller has a group | |
42 | * membership in common with */ | |
43 | if (key->gid != -1 && key->perm & KEY_GRP_ALL) { | |
b6dff3ec | 44 | if (key->gid == cred->fsgid) { |
468ed2b0 DH |
45 | kperm = key->perm >> 8; |
46 | goto use_these_perms; | |
47 | } | |
48 | ||
b6dff3ec | 49 | ret = groups_search(cred->group_info, key->gid); |
468ed2b0 DH |
50 | if (ret) { |
51 | kperm = key->perm >> 8; | |
52 | goto use_these_perms; | |
53 | } | |
54 | } | |
55 | ||
56 | /* otherwise use the least-significant 8-bits */ | |
57 | kperm = key->perm; | |
58 | ||
59 | use_these_perms: | |
c69e8d9c DH |
60 | rcu_read_lock(); |
61 | ||
7ab501db DH |
62 | /* use the top 8-bits of permissions for keys the caller possesses |
63 | * - possessor permissions are additive with other permissions | |
64 | */ | |
65 | if (is_key_possessed(key_ref)) | |
66 | kperm |= key->perm >> 24; | |
67 | ||
468ed2b0 DH |
68 | kperm = kperm & perm & KEY_ALL; |
69 | ||
29db9190 DH |
70 | if (kperm != perm) |
71 | return -EACCES; | |
72 | ||
73 | /* let LSM be the final arbiter */ | |
74 | return security_key_permission(key_ref, context, perm); | |
468ed2b0 DH |
75 | |
76 | } /* end key_task_permission() */ | |
77 | ||
78 | EXPORT_SYMBOL(key_task_permission); | |
b5f545c8 DH |
79 | |
80 | /*****************************************************************************/ | |
81 | /* | |
82 | * validate a key | |
83 | */ | |
84 | int key_validate(struct key *key) | |
85 | { | |
86 | struct timespec now; | |
87 | int ret = 0; | |
88 | ||
89 | if (key) { | |
90 | /* check it's still accessible */ | |
91 | ret = -EKEYREVOKED; | |
92 | if (test_bit(KEY_FLAG_REVOKED, &key->flags) || | |
93 | test_bit(KEY_FLAG_DEAD, &key->flags)) | |
94 | goto error; | |
95 | ||
96 | /* check it hasn't expired */ | |
97 | ret = 0; | |
98 | if (key->expiry) { | |
99 | now = current_kernel_time(); | |
100 | if (now.tv_sec >= key->expiry) | |
101 | ret = -EKEYEXPIRED; | |
102 | } | |
103 | } | |
104 | ||
105 | error: | |
106 | return ret; | |
107 | ||
108 | } /* end key_validate() */ | |
109 | ||
110 | EXPORT_SYMBOL(key_validate); |