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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* Key permission checking
3 *
4 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/export.h>
9#include <linux/security.h>
10#include "internal.h"
11
12/**
13 * key_task_permission - Check a key can be used
14 * @key_ref: The key to check.
15 * @cred: The credentials to use.
16 * @need_perm: The permission required.
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 * The caller must hold either a ref on cred or must hold the RCU readlock.
22 *
23 * Returns 0 if successful, -EACCES if access is denied based on the
24 * permissions bits or the LSM check.
25 */
26int key_task_permission(const key_ref_t key_ref, const struct cred *cred,
27 enum key_need_perm need_perm)
28{
29 struct key *key;
30 key_perm_t kperm, mask;
31 int ret;
32
33 switch (need_perm) {
34 default:
35 WARN_ON(1);
36 return -EACCES;
37 case KEY_NEED_UNLINK:
38 case KEY_SYSADMIN_OVERRIDE:
39 case KEY_AUTHTOKEN_OVERRIDE:
40 case KEY_DEFER_PERM_CHECK:
41 goto lsm;
42
43 case KEY_NEED_VIEW: mask = KEY_OTH_VIEW; break;
44 case KEY_NEED_READ: mask = KEY_OTH_READ; break;
45 case KEY_NEED_WRITE: mask = KEY_OTH_WRITE; break;
46 case KEY_NEED_SEARCH: mask = KEY_OTH_SEARCH; break;
47 case KEY_NEED_LINK: mask = KEY_OTH_LINK; break;
48 case KEY_NEED_SETATTR: mask = KEY_OTH_SETATTR; break;
49 }
50
51 key = key_ref_to_ptr(key_ref);
52
53 /* use the second 8-bits of permissions for keys the caller owns */
54 if (uid_eq(key->uid, cred->fsuid)) {
55 kperm = key->perm >> 16;
56 goto use_these_perms;
57 }
58
59 /* use the third 8-bits of permissions for keys the caller has a group
60 * membership in common with */
61 if (gid_valid(key->gid) && key->perm & KEY_GRP_ALL) {
62 if (gid_eq(key->gid, cred->fsgid)) {
63 kperm = key->perm >> 8;
64 goto use_these_perms;
65 }
66
67 ret = groups_search(cred->group_info, key->gid);
68 if (ret) {
69 kperm = key->perm >> 8;
70 goto use_these_perms;
71 }
72 }
73
74 /* otherwise use the least-significant 8-bits */
75 kperm = key->perm;
76
77use_these_perms:
78
79 /* use the top 8-bits of permissions for keys the caller possesses
80 * - possessor permissions are additive with other permissions
81 */
82 if (is_key_possessed(key_ref))
83 kperm |= key->perm >> 24;
84
85 if ((kperm & mask) != mask)
86 return -EACCES;
87
88 /* let LSM be the final arbiter */
89lsm:
90 return security_key_permission(key_ref, cred, need_perm);
91}
92EXPORT_SYMBOL(key_task_permission);
93
94/**
95 * key_validate - Validate a key.
96 * @key: The key to be validated.
97 *
98 * Check that a key is valid, returning 0 if the key is okay, -ENOKEY if the
99 * key is invalidated, -EKEYREVOKED if the key's type has been removed or if
100 * the key has been revoked or -EKEYEXPIRED if the key has expired.
101 */
102int key_validate(const struct key *key)
103{
104 unsigned long flags = READ_ONCE(key->flags);
105 time64_t expiry = READ_ONCE(key->expiry);
106
107 if (flags & (1 << KEY_FLAG_INVALIDATED))
108 return -ENOKEY;
109
110 /* check it's still accessible */
111 if (flags & ((1 << KEY_FLAG_REVOKED) |
112 (1 << KEY_FLAG_DEAD)))
113 return -EKEYREVOKED;
114
115 /* check it hasn't expired */
116 if (expiry) {
117 if (ktime_get_real_seconds() >= expiry)
118 return -EKEYEXPIRED;
119 }
120
121 return 0;
122}
123EXPORT_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->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, key->gid);
57 if (ret) {
58 kperm = key->perm >> 8;
59 goto use_these_perms;
60 }
61 }
62
63use_other_perms:
64
65 /* otherwise use the least-significant 8-bits */
66 kperm = key->perm;
67
68use_these_perms:
69
70 /* use the top 8-bits of permissions for keys the caller possesses
71 * - possessor permissions are additive with other permissions
72 */
73 if (is_key_possessed(key_ref))
74 kperm |= key->perm >> 24;
75
76 kperm = kperm & perm & KEY_ALL;
77
78 if (kperm != perm)
79 return -EACCES;
80
81 /* let LSM be the final arbiter */
82 return security_key_permission(key_ref, cred, perm);
83}
84EXPORT_SYMBOL(key_task_permission);
85
86/**
87 * key_validate - Validate a key.
88 * @key: The key to be validated.
89 *
90 * Check that a key is valid, returning 0 if the key is okay, -EKEYREVOKED if
91 * the key's type has been removed or if the key has been revoked or
92 * -EKEYEXPIRED if the key has expired.
93 */
94int key_validate(struct key *key)
95{
96 struct timespec now;
97 int ret = 0;
98
99 if (key) {
100 /* check it's still accessible */
101 ret = -EKEYREVOKED;
102 if (test_bit(KEY_FLAG_REVOKED, &key->flags) ||
103 test_bit(KEY_FLAG_DEAD, &key->flags))
104 goto error;
105
106 /* check it hasn't expired */
107 ret = 0;
108 if (key->expiry) {
109 now = current_kernel_time();
110 if (now.tv_sec >= key->expiry)
111 ret = -EKEYEXPIRED;
112 }
113 }
114
115error:
116 return ret;
117}
118EXPORT_SYMBOL(key_validate);