crypto/block-qcow.c

   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 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
  29 #include "crypto/block-qcow.h"
  30 #include "crypto/secret.h"
  31
  32 #define QCRYPTO_BLOCK_QCOW_SECTOR_SIZE 512
  33
  34
  35 static bool
  36 qcrypto_block_qcow_has_format(const uint8_t *buf G_GNUC_UNUSED,
  37                               size_t buf_size G_GNUC_UNUSED)
  38 {
  39     return false;
  40 }
  41
  42
  43 static int
  44 qcrypto_block_qcow_init(QCryptoBlock *block,
  45                         const char *keysecret,
  46                         Error **errp)
  47 {
  48     char *password;
  49     int ret;
  50     uint8_t keybuf[16];
  51     int len;
  52
  53     memset(keybuf, 0, 16);
  54
  55     password = qcrypto_secret_lookup_as_utf8(keysecret, errp);
  56     if (!password) {
  57         return -1;
  58     }
  59
  60     len = strlen(password);
  61     memcpy(keybuf, password, MIN(len, sizeof(keybuf)));
  62     g_free(password);
  63
  64     block->niv = qcrypto_cipher_get_iv_len(QCRYPTO_CIPHER_ALG_AES_128,
  65                                            QCRYPTO_CIPHER_MODE_CBC);
  66     block->ivgen = qcrypto_ivgen_new(QCRYPTO_IVGEN_ALG_PLAIN64,
  67                                      0, 0, NULL, 0, errp);
  68     if (!block->ivgen) {
  69         ret = -ENOTSUP;
  70         goto fail;
  71     }
  72
  73     block->cipher = qcrypto_cipher_new(QCRYPTO_CIPHER_ALG_AES_128,
  74                                        QCRYPTO_CIPHER_MODE_CBC,
  75                                        keybuf, G_N_ELEMENTS(keybuf),
  76                                        errp);
  77     if (!block->cipher) {
  78         ret = -ENOTSUP;
  79         goto fail;
  80     }
  81
  82     block->payload_offset = 0;
  83
  84     return 0;
  85
  86  fail:
  87     qcrypto_cipher_free(block->cipher);
  88     qcrypto_ivgen_free(block->ivgen);
  89     return ret;
  90 }
  91
  92
  93 static int
  94 qcrypto_block_qcow_open(QCryptoBlock *block,
  95                         QCryptoBlockOpenOptions *options,
  96                         QCryptoBlockReadFunc readfunc G_GNUC_UNUSED,
  97                         void *opaque G_GNUC_UNUSED,
  98                         unsigned int flags,
  99                         Error **errp)
 100 {
 101     if (flags & QCRYPTO_BLOCK_OPEN_NO_IO) {
 102         return 0;
 103     } else {
 104         if (!options->u.qcow.key_secret) {
 105             error_setg(errp,
 106                        "Parameter 'key-secret' is required for cipher");
 107             return -1;
 108         }
 109         return qcrypto_block_qcow_init(block,
 110                                        options->u.qcow.key_secret, errp);
 111     }
 112 }
 113
 114
 115 static int
 116 qcrypto_block_qcow_create(QCryptoBlock *block,
 117                           QCryptoBlockCreateOptions *options,
 118                           QCryptoBlockInitFunc initfunc G_GNUC_UNUSED,
 119                           QCryptoBlockWriteFunc writefunc G_GNUC_UNUSED,
 120                           void *opaque G_GNUC_UNUSED,
 121                           Error **errp)
 122 {
 123     if (!options->u.qcow.key_secret) {
 124         error_setg(errp, "Parameter 'key-secret' is required for cipher");
 125         return -1;
 126     }
 127     /* QCow2 has no special header, since everything is hardwired */
 128     return qcrypto_block_qcow_init(block, options->u.qcow.key_secret, errp);
 129 }
 130
 131
 132 static void
 133 qcrypto_block_qcow_cleanup(QCryptoBlock *block)
 134 {
 135 }
 136
 137
 138 static int
 139 qcrypto_block_qcow_decrypt(QCryptoBlock *block,
 140                            uint64_t startsector,
 141                            uint8_t *buf,
 142                            size_t len,
 143                            Error **errp)
 144 {
 145     return qcrypto_block_decrypt_helper(block->cipher,
 146                                         block->niv, block->ivgen,
 147                                         QCRYPTO_BLOCK_QCOW_SECTOR_SIZE,
 148                                         startsector, buf, len, errp);
 149 }
 150
 151
 152 static int
 153 qcrypto_block_qcow_encrypt(QCryptoBlock *block,
 154                            uint64_t startsector,
 155                            uint8_t *buf,
 156                            size_t len,
 157                            Error **errp)
 158 {
 159     return qcrypto_block_encrypt_helper(block->cipher,
 160                                         block->niv, block->ivgen,
 161                                         QCRYPTO_BLOCK_QCOW_SECTOR_SIZE,
 162                                         startsector, buf, len, errp);
 163 }
 164
 165
 166 const QCryptoBlockDriver qcrypto_block_driver_qcow = {
 167     .open = qcrypto_block_qcow_open,
 168     .create = qcrypto_block_qcow_create,
 169     .cleanup = qcrypto_block_qcow_cleanup,
 170     .decrypt = qcrypto_block_qcow_decrypt,
 171     .encrypt = qcrypto_block_qcow_encrypt,
 172     .has_format = qcrypto_block_qcow_has_format,
 173 };