xref: /openbmc/qemu/crypto/block-qcow.c (revision 05caa062)
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
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
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
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
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
141 qcrypto_block_qcow_cleanup(QCryptoBlock *block)
142 {
143 }
144 
145 
146 static int
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
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