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Member "cryptsetup-2.4.3/lib/utils_keyring.c" (13 Jan 2022, 5281 Bytes) of package /linux/misc/cryptsetup-2.4.3.tar.xz:
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1 /*
2 * kernel keyring utilities
3 *
4 * Copyright (C) 2016-2021 Red Hat, Inc. All rights reserved.
5 * Copyright (C) 2016-2021 Ondrej Kozina
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version 2
10 * of the License, or (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
20 */
21
22 #include <errno.h>
23 #include <stdio.h>
24 #include <stdlib.h>
25 #include <unistd.h>
26 #include <sys/syscall.h>
27
28 #include "libcryptsetup.h"
29 #include "libcryptsetup_macros.h"
30 #include "utils_keyring.h"
31
32 #ifndef HAVE_KEY_SERIAL_T
33 #define HAVE_KEY_SERIAL_T
34 typedef int32_t key_serial_t;
35 #endif
36
37 #ifdef KERNEL_KEYRING
38
39 static const struct {
40 key_type_t type;
41 const char *type_name;
42 } key_types[] = {
43 { LOGON_KEY, "logon" },
44 { USER_KEY, "user" },
45 };
46
47 #include <linux/keyctl.h>
48
49 /* request_key */
50 static key_serial_t request_key(const char *type,
51 const char *description,
52 const char *callout_info,
53 key_serial_t keyring)
54 {
55 return syscall(__NR_request_key, type, description, callout_info, keyring);
56 }
57
58 /* add_key */
59 static key_serial_t add_key(const char *type,
60 const char *description,
61 const void *payload,
62 size_t plen,
63 key_serial_t keyring)
64 {
65 return syscall(__NR_add_key, type, description, payload, plen, keyring);
66 }
67
68 /* keyctl_read */
69 static long keyctl_read(key_serial_t key, char *buffer, size_t buflen)
70 {
71 return syscall(__NR_keyctl, KEYCTL_READ, key, buffer, buflen);
72 }
73
74 /* keyctl_revoke */
75 static long keyctl_revoke(key_serial_t key)
76 {
77 return syscall(__NR_keyctl, KEYCTL_REVOKE, key);
78 }
79
80 /* keyctl_unlink */
81 static long keyctl_unlink(key_serial_t key, key_serial_t keyring)
82 {
83 return syscall(__NR_keyctl, KEYCTL_UNLINK, key, keyring);
84 }
85 #endif
86
87 int keyring_check(void)
88 {
89 #ifdef KERNEL_KEYRING
90 /* logon type key descriptions must be in format "prefix:description" */
91 return syscall(__NR_request_key, "logon", "dummy", NULL, 0) == -1l && errno != ENOSYS;
92 #else
93 return 0;
94 #endif
95 }
96
97 int keyring_add_key_in_thread_keyring(key_type_t ktype, const char *key_desc, const void *key, size_t key_size)
98 {
99 #ifdef KERNEL_KEYRING
100 key_serial_t kid;
101 const char *type_name = key_type_name(ktype);
102
103 if (!type_name || !key_desc)
104 return -EINVAL;
105
106 kid = add_key(type_name, key_desc, key, key_size, KEY_SPEC_THREAD_KEYRING);
107 if (kid < 0)
108 return -errno;
109
110 return 0;
111 #else
112 return -ENOTSUP;
113 #endif
114 }
115
116 /* currently used in client utilities only */
117 int keyring_add_key_in_user_keyring(key_type_t ktype, const char *key_desc, const void *key, size_t key_size)
118 {
119 #ifdef KERNEL_KEYRING
120 const char *type_name = key_type_name(ktype);
121 key_serial_t kid;
122
123 if (!type_name || !key_desc)
124 return -EINVAL;
125
126 kid = add_key(type_name, key_desc, key, key_size, KEY_SPEC_USER_KEYRING);
127 if (kid < 0)
128 return -errno;
129
130 return 0;
131 #else
132 return -ENOTSUP;
133 #endif
134 }
135
136 /* alias for the same code */
137 int keyring_get_key(const char *key_desc,
138 char **key,
139 size_t *key_size)
140 {
141 return keyring_get_passphrase(key_desc, key, key_size);
142 }
143
144 int keyring_get_passphrase(const char *key_desc,
145 char **passphrase,
146 size_t *passphrase_len)
147 {
148 #ifdef KERNEL_KEYRING
149 int err;
150 key_serial_t kid;
151 long ret;
152 char *buf = NULL;
153 size_t len = 0;
154
155 do
156 kid = request_key(key_type_name(USER_KEY), key_desc, NULL, 0);
157 while (kid < 0 && errno == EINTR);
158
159 if (kid < 0)
160 return -errno;
161
162 /* just get payload size */
163 ret = keyctl_read(kid, NULL, 0);
164 if (ret > 0) {
165 len = ret;
166 buf = malloc(len);
167 if (!buf)
168 return -ENOMEM;
169
170 /* retrieve actual payload data */
171 ret = keyctl_read(kid, buf, len);
172 }
173
174 if (ret < 0) {
175 err = errno;
176 if (buf)
177 crypt_safe_memzero(buf, len);
178 free(buf);
179 return -err;
180 }
181
182 *passphrase = buf;
183 *passphrase_len = len;
184
185 return 0;
186 #else
187 return -ENOTSUP;
188 #endif
189 }
190
191 static int keyring_revoke_and_unlink_key_type(const char *type_name, const char *key_desc)
192 {
193 #ifdef KERNEL_KEYRING
194 key_serial_t kid;
195
196 if (!type_name || !key_desc)
197 return -EINVAL;
198
199 do
200 kid = request_key(type_name, key_desc, NULL, 0);
201 while (kid < 0 && errno == EINTR);
202
203 if (kid < 0)
204 return 0;
205
206 if (keyctl_revoke(kid))
207 return -errno;
208
209 /*
210 * best effort only. the key could have been linked
211 * in some other keyring and its payload is now
212 * revoked anyway.
213 */
214 keyctl_unlink(kid, KEY_SPEC_THREAD_KEYRING);
215 keyctl_unlink(kid, KEY_SPEC_PROCESS_KEYRING);
216 keyctl_unlink(kid, KEY_SPEC_USER_KEYRING);
217
218 return 0;
219 #else
220 return -ENOTSUP;
221 #endif
222 }
223
224 const char *key_type_name(key_type_t type)
225 {
226 #ifdef KERNEL_KEYRING
227 unsigned int i;
228
229 for (i = 0; i < ARRAY_SIZE(key_types); i++)
230 if (type == key_types[i].type)
231 return key_types[i].type_name;
232 #endif
233 return NULL;
234 }
235
236 int keyring_revoke_and_unlink_key(key_type_t ktype, const char *key_desc)
237 {
238 return keyring_revoke_and_unlink_key_type(key_type_name(ktype), key_desc);
239 }