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/*
* QEMU Crypto block device encryption QCow/QCow2 AES-CBC format
*
* Copyright (c) 2015-2016 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*
*/
/*
* Note that the block encryption implemented in this file is broken
* by design. This exists only to allow data to be liberated from
* existing qcow[2] images and should not be used in any new areas.
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "block-qcow.h"
#include "crypto/secret.h"
#define QCRYPTO_BLOCK_QCOW_SECTOR_SIZE 512
static bool
qcrypto_block_qcow_has_format(const uint8_t *buf G_GNUC_UNUSED,
size_t buf_size G_GNUC_UNUSED)
{
return false;
}
static int
qcrypto_block_qcow_init(QCryptoBlock *block,
const char *keysecret,
Error **errp)
{
char *password;
int ret;
uint8_t keybuf[16];
int len;
memset(keybuf, 0, 16);
password = qcrypto_secret_lookup_as_utf8(keysecret, errp);
if (!password) {
return -1;
}
len = strlen(password);
memcpy(keybuf, password, MIN(len, sizeof(keybuf)));
g_free(password);
block->niv = qcrypto_cipher_get_iv_len(QCRYPTO_CIPHER_ALG_AES_128,
QCRYPTO_CIPHER_MODE_CBC);
block->ivgen = qcrypto_ivgen_new(QCRYPTO_IVGEN_ALG_PLAIN64,
0, 0, NULL, 0, errp);
if (!block->ivgen) {
ret = -ENOTSUP;
goto fail;
}
block->cipher = qcrypto_cipher_new(QCRYPTO_CIPHER_ALG_AES_128,
QCRYPTO_CIPHER_MODE_CBC,
keybuf, G_N_ELEMENTS(keybuf),
errp);
if (!block->cipher) {
ret = -ENOTSUP;
goto fail;
}
block->sector_size = QCRYPTO_BLOCK_QCOW_SECTOR_SIZE;
block->payload_offset = 0;
return 0;
fail:
qcrypto_cipher_free(block->cipher);
qcrypto_ivgen_free(block->ivgen);
return ret;
}
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)
{
if (flags & QCRYPTO_BLOCK_OPEN_NO_IO) {
return 0;
} else {
if (!options->u.qcow.key_secret) {
error_setg(errp,
"Parameter '%skey-secret' is required for cipher",
optprefix ? optprefix : "");
return -1;
}
return qcrypto_block_qcow_init(block,
options->u.qcow.key_secret, errp);
}
}
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)
{
if (!options->u.qcow.key_secret) {
error_setg(errp, "Parameter '%skey-secret' is required for cipher",
optprefix ? optprefix : "");
return -1;
}
/* QCow2 has no special header, since everything is hardwired */
return qcrypto_block_qcow_init(block, options->u.qcow.key_secret, errp);
}
static void
qcrypto_block_qcow_cleanup(QCryptoBlock *block)
{
}
static int
qcrypto_block_qcow_decrypt(QCryptoBlock *block,
uint64_t offset,
uint8_t *buf,
size_t len,
Error **errp)
{
assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE));
assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE));
return qcrypto_block_decrypt_helper(block->cipher,
block->niv, block->ivgen,
QCRYPTO_BLOCK_QCOW_SECTOR_SIZE,
offset, buf, len, errp);
}
static int
qcrypto_block_qcow_encrypt(QCryptoBlock *block,
uint64_t offset,
uint8_t *buf,
size_t len,
Error **errp)
{
assert(QEMU_IS_ALIGNED(offset, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE));
assert(QEMU_IS_ALIGNED(len, QCRYPTO_BLOCK_QCOW_SECTOR_SIZE));
return qcrypto_block_encrypt_helper(block->cipher,
block->niv, block->ivgen,
QCRYPTO_BLOCK_QCOW_SECTOR_SIZE,
offset, buf, len, errp);
}
const QCryptoBlockDriver qcrypto_block_driver_qcow = {
.open = qcrypto_block_qcow_open,
.create = qcrypto_block_qcow_create,
.cleanup = qcrypto_block_qcow_cleanup,
.decrypt = qcrypto_block_qcow_decrypt,
.encrypt = qcrypto_block_qcow_encrypt,
.has_format = qcrypto_block_qcow_has_format,
};
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