Loading...
1/* Key permission checking
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>
13#include <linux/security.h>
14#include "internal.h"
15
16/**
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.
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 *
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.
29 */
30int key_task_permission(const key_ref_t key_ref, const struct cred *cred,
31 unsigned perm)
32{
33 struct key *key;
34 key_perm_t kperm;
35 int ret;
36
37 key = key_ref_to_ptr(key_ref);
38
39 /* use the second 8-bits of permissions for keys the caller owns */
40 if (uid_eq(key->uid, cred->fsuid)) {
41 kperm = key->perm >> 16;
42 goto use_these_perms;
43 }
44
45 /* use the third 8-bits of permissions for keys the caller has a group
46 * membership in common with */
47 if (gid_valid(key->gid) && key->perm & KEY_GRP_ALL) {
48 if (gid_eq(key->gid, cred->fsgid)) {
49 kperm = key->perm >> 8;
50 goto use_these_perms;
51 }
52
53 ret = groups_search(cred->group_info, key->gid);
54 if (ret) {
55 kperm = key->perm >> 8;
56 goto use_these_perms;
57 }
58 }
59
60 /* otherwise use the least-significant 8-bits */
61 kperm = key->perm;
62
63use_these_perms:
64
65 /* use the top 8-bits of permissions for keys the caller possesses
66 * - possessor permissions are additive with other permissions
67 */
68 if (is_key_possessed(key_ref))
69 kperm |= key->perm >> 24;
70
71 kperm = kperm & perm & KEY_NEED_ALL;
72
73 if (kperm != perm)
74 return -EACCES;
75
76 /* let LSM be the final arbiter */
77 return security_key_permission(key_ref, cred, perm);
78}
79EXPORT_SYMBOL(key_task_permission);
80
81/**
82 * key_validate - Validate a key.
83 * @key: The key to be validated.
84 *
85 * Check that a key is valid, returning 0 if the key is okay, -ENOKEY if the
86 * key is invalidated, -EKEYREVOKED if the key's type has been removed or if
87 * the key has been revoked or -EKEYEXPIRED if the key has expired.
88 */
89int key_validate(const struct key *key)
90{
91 unsigned long flags = key->flags;
92
93 if (flags & (1 << KEY_FLAG_INVALIDATED))
94 return -ENOKEY;
95
96 /* check it's still accessible */
97 if (flags & ((1 << KEY_FLAG_REVOKED) |
98 (1 << KEY_FLAG_DEAD)))
99 return -EKEYREVOKED;
100
101 /* check it hasn't expired */
102 if (key->expiry) {
103 struct timespec now = current_kernel_time();
104 if (now.tv_sec >= key->expiry)
105 return -EKEYEXPIRED;
106 }
107
108 return 0;
109}
110EXPORT_SYMBOL(key_validate);
1/* Key permission checking
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>
13#include <linux/security.h>
14#include "internal.h"
15
16/**
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.
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 *
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.
29 */
30int key_task_permission(const key_ref_t key_ref, const struct cred *cred,
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
39 if (key->user->user_ns != cred->user_ns)
40 goto use_other_perms;
41
42 /* use the second 8-bits of permissions for keys the caller owns */
43 if (key->uid == cred->fsuid) {
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) {
51 if (key->gid == cred->fsgid) {
52 kperm = key->perm >> 8;
53 goto use_these_perms;
54 }
55
56 ret = groups_search(cred->group_info,
57 make_kgid(current_user_ns(), key->gid));
58 if (ret) {
59 kperm = key->perm >> 8;
60 goto use_these_perms;
61 }
62 }
63
64use_other_perms:
65
66 /* otherwise use the least-significant 8-bits */
67 kperm = key->perm;
68
69use_these_perms:
70
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
77 kperm = kperm & perm & KEY_ALL;
78
79 if (kperm != perm)
80 return -EACCES;
81
82 /* let LSM be the final arbiter */
83 return security_key_permission(key_ref, cred, perm);
84}
85EXPORT_SYMBOL(key_task_permission);
86
87/**
88 * key_validate - Validate a key.
89 * @key: The key to be validated.
90 *
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.
94 */
95int key_validate(const struct key *key)
96{
97 unsigned long flags = key->flags;
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;
112 }
113
114 return 0;
115}
116EXPORT_SYMBOL(key_validate);