1 /*
2 * QEMU Crypto block device encryption QCow/QCow2 AES-CBC format
3 *
4 * Copyright (c) 2015-2016 Red Hat, Inc.
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
18 *
19 */
20
21 /*
22 * Note that the block encryption implemented in this file is broken
23 * by design. This exists only to allow data to be liberated from
24 * existing qcow[2] images and should not be used in any new areas.
25 */
26
27 #include "qemu/osdep.h"
28 #include "qapi/error.h"
29
30 #include "block-qcow.h"
31 #include "crypto/secret.h"
32
33 #define QCRYPTO_BLOCK_QCOW_SECTOR_SIZE 512
34
35
36 static bool
qcrypto_block_qcow_has_format(const uint8_t * buf G_GNUC_UNUSED,size_t buf_size G_GNUC_UNUSED)37 qcrypto_block_qcow_has_format(const uint8_t *buf G_GNUC_UNUSED,
38 size_t buf_size G_GNUC_UNUSED)
39 {
40 return false;
41 }
42
43
44 static int
qcrypto_block_qcow_init(QCryptoBlock * block,const char * keysecret,Error ** errp)45 qcrypto_block_qcow_init(QCryptoBlock *block,
46 const char *keysecret,
47 Error **errp)
48 {
49 char *password;
50 int ret;
51 uint8_t keybuf[16];
52 int len;
53
54 memset(keybuf, 0, 16);
55
56 password = qcrypto_secret_lookup_as_utf8(keysecret, errp);
57 if (!password) {
58 return -1;
59 }
60
61 len = strlen(password);
62 memcpy(keybuf, password, MIN(len, sizeof(keybuf)));
63 g_free(password);
64
65 block->niv = qcrypto_cipher_get_iv_len(QCRYPTO_CIPHER_ALG_AES_128,
66 QCRYPTO_CIPHER_MODE_CBC);
67 block->ivgen = qcrypto_ivgen_new(QCRYPTO_IVGEN_ALG_PLAIN64,
68 0, 0, NULL, 0, errp);
69 if (!block->ivgen) {
70 ret = -ENOTSUP;
71 goto fail;
72 }
73
74 ret = qcrypto_block_init_cipher(block, QCRYPTO_CIPHER_ALG_AES_128,
75 QCRYPTO_CIPHER_MODE_CBC,
76 keybuf, G_N_ELEMENTS(keybuf),
77 errp);
78 if (ret < 0) {
79 ret = -ENOTSUP;
80 goto fail;
81 }
82
83 block->sector_size = QCRYPTO_BLOCK_QCOW_SECTOR_SIZE;
84 block->payload_offset = 0;
85
86 return 0;
87
88 fail:
89 qcrypto_block_free_cipher(block);
90 qcrypto_ivgen_free(block->ivgen);
91 return ret;
92 }
93
94
95 static int
qcrypto_block_qcow_open(QCryptoBlock * block,QCryptoBlockOpenOptions * options,const char * optprefix,QCryptoBlockReadFunc readfunc G_GNUC_UNUSED,void * opaque G_GNUC_UNUSED,unsigned int flags,Error ** errp)96 qcrypto_block_qcow_open(QCryptoBlock *block,
97 QCryptoBlockOpenOptions *options,
98 const char *optprefix,
99 QCryptoBlockReadFunc readfunc G_GNUC_UNUSED,
100 void *opaque G_GNUC_UNUSED,
101 unsigned int flags,
102 Error **errp)
103 {
104 if (flags & QCRYPTO_BLOCK_OPEN_NO_IO) {
105 block->sector_size = QCRYPTO_BLOCK_QCOW_SECTOR_SIZE;
106 block->payload_offset = 0;
107 return 0;
108 } else {
109 if (!options->u.qcow.key_secret) {
110 error_setg(errp,
111 "Parameter '%skey-secret' is required for cipher",
112 optprefix ? optprefix : "");
113 return -1;
114 }
115 return qcrypto_block_qcow_init(block, options->u.qcow.key_secret,
116 errp);
117 }
118 }
119
120
121 static int
qcrypto_block_qcow_create(QCryptoBlock * block,QCryptoBlockCreateOptions * options,const char * optprefix,QCryptoBlockInitFunc initfunc G_GNUC_UNUSED,QCryptoBlockWriteFunc writefunc G_GNUC_UNUSED,void * opaque G_GNUC_UNUSED,Error ** errp)122 qcrypto_block_qcow_create(QCryptoBlock *block,
123 QCryptoBlockCreateOptions *options,
124 const char *optprefix,
125 QCryptoBlockInitFunc initfunc G_GNUC_UNUSED,
126 QCryptoBlockWriteFunc writefunc G_GNUC_UNUSED,
127 void *opaque G_GNUC_UNUSED,
128 Error **errp)
129 {
130 if (!options->u.qcow.key_secret) {
131 error_setg(errp, "Parameter '%skey-secret' is required for cipher",
132 optprefix ? optprefix : "");
133 return -1;
134 }
135 /* QCow2 has no special header, since everything is hardwired */
136 return qcrypto_block_qcow_init(block, options->u.qcow.key_secret, errp);
137 }
138
139
140 static void
qcrypto_block_qcow_cleanup(QCryptoBlock * block)141 qcrypto_block_qcow_cleanup(QCryptoBlock *block)
142 {
143 }
144
145
146 static int
qcrypto_block_qcow_decrypt(QCryptoBlock * block,uint64_t offset,uint8_t * buf,size_t len,Error ** errp)147 qcrypto_block_qcow_decrypt(QCryptoBlock *block,
148 uint64_t offset,
149 uint8_t *buf,
150 size_t len,
151 Error **errp)
152 {
153 assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE));
154 assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE));
155 return qcrypto_block_decrypt_helper(block,
156 QCRYPTO_BLOCK_QCOW_SECTOR_SIZE,
157 offset, buf, len, errp);
158 }
159
160
161 static int
qcrypto_block_qcow_encrypt(QCryptoBlock * block,uint64_t offset,uint8_t * buf,size_t len,Error ** errp)162 qcrypto_block_qcow_encrypt(QCryptoBlock *block,
163 uint64_t offset,
164 uint8_t *buf,
165 size_t len,
166 Error **errp)
167 {
168 assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE));
169 assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE));
170 return qcrypto_block_encrypt_helper(block,
171 QCRYPTO_BLOCK_QCOW_SECTOR_SIZE,
172 offset, buf, len, errp);
173 }
174
175
176 const QCryptoBlockDriver qcrypto_block_driver_qcow = {
177 .open = qcrypto_block_qcow_open,
178 .create = qcrypto_block_qcow_create,
179 .cleanup = qcrypto_block_qcow_cleanup,
180 .decrypt = qcrypto_block_qcow_decrypt,
181 .encrypt = qcrypto_block_qcow_encrypt,
182 .has_format = qcrypto_block_qcow_has_format,
183 };
184