Commit | Line | Data |
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973c9f4f | 1 | /* Key permission checking |
468ed2b0 DH |
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 | ||
d84f4f99 DH |
16 | /** |
17 | * key_task_permission - Check a key can be used | |
973c9f4f DH |
18 | * @key_ref: The key to check. |
19 | * @cred: The credentials to use. | |
20 | * @perm: The permissions to check for. | |
d84f4f99 DH |
21 | * |
22 | * Check to see whether permission is granted to use a key in the desired way, | |
23 | * but permit the security modules to override. | |
24 | * | |
973c9f4f DH |
25 | * The caller must hold either a ref on cred or must hold the RCU readlock. |
26 | * | |
27 | * Returns 0 if successful, -EACCES if access is denied based on the | |
28 | * permissions bits or the LSM check. | |
468ed2b0 | 29 | */ |
d84f4f99 | 30 | int key_task_permission(const key_ref_t key_ref, const struct cred *cred, |
468ed2b0 DH |
31 | key_perm_t perm) |
32 | { | |
33 | struct key *key; | |
34 | key_perm_t kperm; | |
35 | int ret; | |
36 | ||
37 | key = key_ref_to_ptr(key_ref); | |
38 | ||
c4a4d603 | 39 | if (key->user->user_ns != cred->user_ns) |
8ff3bc31 SH |
40 | goto use_other_perms; |
41 | ||
468ed2b0 | 42 | /* use the second 8-bits of permissions for keys the caller owns */ |
b6dff3ec | 43 | if (key->uid == cred->fsuid) { |
468ed2b0 DH |
44 | kperm = key->perm >> 16; |
45 | goto use_these_perms; | |
46 | } | |
47 | ||
48 | /* use the third 8-bits of permissions for keys the caller has a group | |
49 | * membership in common with */ | |
50 | if (key->gid != -1 && key->perm & KEY_GRP_ALL) { | |
b6dff3ec | 51 | if (key->gid == cred->fsgid) { |
468ed2b0 DH |
52 | kperm = key->perm >> 8; |
53 | goto use_these_perms; | |
54 | } | |
55 | ||
ae2975bc EB |
56 | ret = groups_search(cred->group_info, |
57 | make_kgid(current_user_ns(), key->gid)); | |
468ed2b0 DH |
58 | if (ret) { |
59 | kperm = key->perm >> 8; | |
60 | goto use_these_perms; | |
61 | } | |
62 | } | |
63 | ||
8ff3bc31 SH |
64 | use_other_perms: |
65 | ||
468ed2b0 DH |
66 | /* otherwise use the least-significant 8-bits */ |
67 | kperm = key->perm; | |
68 | ||
69 | use_these_perms: | |
c69e8d9c | 70 | |
7ab501db DH |
71 | /* use the top 8-bits of permissions for keys the caller possesses |
72 | * - possessor permissions are additive with other permissions | |
73 | */ | |
74 | if (is_key_possessed(key_ref)) | |
75 | kperm |= key->perm >> 24; | |
76 | ||
468ed2b0 DH |
77 | kperm = kperm & perm & KEY_ALL; |
78 | ||
29db9190 DH |
79 | if (kperm != perm) |
80 | return -EACCES; | |
81 | ||
82 | /* let LSM be the final arbiter */ | |
d84f4f99 | 83 | return security_key_permission(key_ref, cred, perm); |
a8b17ed0 | 84 | } |
468ed2b0 | 85 | EXPORT_SYMBOL(key_task_permission); |
b5f545c8 | 86 | |
973c9f4f DH |
87 | /** |
88 | * key_validate - Validate a key. | |
89 | * @key: The key to be validated. | |
90 | * | |
fd75815f DH |
91 | * Check that a key is valid, returning 0 if the key is okay, -ENOKEY if the |
92 | * key is invalidated, -EKEYREVOKED if the key's type has been removed or if | |
93 | * the key has been revoked or -EKEYEXPIRED if the key has expired. | |
b5f545c8 | 94 | */ |
b404aef7 | 95 | int key_validate(const struct key *key) |
b5f545c8 | 96 | { |
fd75815f | 97 | unsigned long flags = key->flags; |
b404aef7 DH |
98 | |
99 | if (flags & (1 << KEY_FLAG_INVALIDATED)) | |
100 | return -ENOKEY; | |
101 | ||
102 | /* check it's still accessible */ | |
103 | if (flags & ((1 << KEY_FLAG_REVOKED) | | |
104 | (1 << KEY_FLAG_DEAD))) | |
105 | return -EKEYREVOKED; | |
106 | ||
107 | /* check it hasn't expired */ | |
108 | if (key->expiry) { | |
109 | struct timespec now = current_kernel_time(); | |
110 | if (now.tv_sec >= key->expiry) | |
111 | return -EKEYEXPIRED; | |
b5f545c8 DH |
112 | } |
113 | ||
b404aef7 | 114 | return 0; |
a8b17ed0 | 115 | } |
b5f545c8 | 116 | EXPORT_SYMBOL(key_validate); |