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c01c214b69
qemu/block/crypto.c
Daniel P. Berrange c01c214b69 block: remove all encryption handling APIs 
Now that all encryption keys must be provided upfront via
the QCryptoSecret API and associated block driver properties
there is no need for any explicit encryption handling APIs
in the block layer. Encryption can be handled transparently
within the block driver. We only retain an API for querying
whether an image is encrypted or not, since that is a
potentially useful piece of metadata to report to the user.

Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170623162419.26068-18-berrange@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-07-11 17:44:56 +02:00

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/*
* QEMU block full disk encryption
*
* 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/>.
*
*/
#include "qemu/osdep.h"
#include "block/block_int.h"
#include "sysemu/block-backend.h"
#include "crypto/block.h"
#include "qapi/opts-visitor.h"
#include "qapi/qobject-input-visitor.h"
#include "qapi-visit.h"
#include "qapi/error.h"
#include "block/crypto.h"
typedef struct BlockCrypto BlockCrypto;
struct BlockCrypto {
QCryptoBlock *block;
};
static int block_crypto_probe_generic(QCryptoBlockFormat format,
const uint8_t *buf,
int buf_size,
const char *filename)
{
if (qcrypto_block_has_format(format, buf, buf_size)) {
return 100;
} else {
return 0;
}
}
static ssize_t block_crypto_read_func(QCryptoBlock *block,
size_t offset,
uint8_t *buf,
size_t buflen,
void *opaque,
Error **errp)
{
BlockDriverState *bs = opaque;
ssize_t ret;
ret = bdrv_pread(bs->file, offset, buf, buflen);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not read encryption header");
return ret;
}
return ret;
}
struct BlockCryptoCreateData {
const char *filename;
QemuOpts *opts;
BlockBackend *blk;
uint64_t size;
};
static ssize_t block_crypto_write_func(QCryptoBlock *block,
size_t offset,
const uint8_t *buf,
size_t buflen,
void *opaque,
Error **errp)
{
struct BlockCryptoCreateData *data = opaque;
ssize_t ret;
ret = blk_pwrite(data->blk, offset, buf, buflen, 0);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not write encryption header");
return ret;
}
return ret;
}
static ssize_t block_crypto_init_func(QCryptoBlock *block,
size_t headerlen,
void *opaque,
Error **errp)
{
struct BlockCryptoCreateData *data = opaque;
int ret;
/* User provided size should reflect amount of space made
* available to the guest, so we must take account of that
* which will be used by the crypto header
*/
data->size += headerlen;
qemu_opt_set_number(data->opts, BLOCK_OPT_SIZE, data->size, &error_abort);
ret = bdrv_create_file(data->filename, data->opts, errp);
if (ret < 0) {
return -1;
}
data->blk = blk_new_open(data->filename, NULL, NULL,
BDRV_O_RDWR | BDRV_O_PROTOCOL, errp);
if (!data->blk) {
return -1;
}
return 0;
}
static QemuOptsList block_crypto_runtime_opts_luks = {
.name = "crypto",
.head = QTAILQ_HEAD_INITIALIZER(block_crypto_runtime_opts_luks.head),
.desc = {
BLOCK_CRYPTO_OPT_DEF_LUKS_KEY_SECRET(""),
{ /* end of list */ }
},
};
static QemuOptsList block_crypto_create_opts_luks = {
.name = "crypto",
.head = QTAILQ_HEAD_INITIALIZER(block_crypto_create_opts_luks.head),
.desc = {
{
.name = BLOCK_OPT_SIZE,
.type = QEMU_OPT_SIZE,
.help = "Virtual disk size"
},
BLOCK_CRYPTO_OPT_DEF_LUKS_KEY_SECRET(""),
BLOCK_CRYPTO_OPT_DEF_LUKS_CIPHER_ALG(""),
BLOCK_CRYPTO_OPT_DEF_LUKS_CIPHER_MODE(""),
BLOCK_CRYPTO_OPT_DEF_LUKS_IVGEN_ALG(""),
BLOCK_CRYPTO_OPT_DEF_LUKS_IVGEN_HASH_ALG(""),
BLOCK_CRYPTO_OPT_DEF_LUKS_HASH_ALG(""),
BLOCK_CRYPTO_OPT_DEF_LUKS_ITER_TIME(""),
{ /* end of list */ }
},
};
QCryptoBlockOpenOptions *
block_crypto_open_opts_init(QCryptoBlockFormat format,
QDict *opts,
Error **errp)
{
Visitor *v;
QCryptoBlockOpenOptions *ret = NULL;
Error *local_err = NULL;
ret = g_new0(QCryptoBlockOpenOptions, 1);
ret->format = format;
v = qobject_input_visitor_new_keyval(QOBJECT(opts));
visit_start_struct(v, NULL, NULL, 0, &local_err);
if (local_err) {
goto out;
}
switch (format) {
case Q_CRYPTO_BLOCK_FORMAT_LUKS:
visit_type_QCryptoBlockOptionsLUKS_members(
v, &ret->u.luks, &local_err);
break;
case Q_CRYPTO_BLOCK_FORMAT_QCOW:
visit_type_QCryptoBlockOptionsQCow_members(
v, &ret->u.qcow, &local_err);
break;
default:
error_setg(&local_err, "Unsupported block format %d", format);
break;
}
if (!local_err) {
visit_check_struct(v, &local_err);
}
visit_end_struct(v, NULL);
out:
if (local_err) {
error_propagate(errp, local_err);
qapi_free_QCryptoBlockOpenOptions(ret);
ret = NULL;
}
visit_free(v);
return ret;
}
QCryptoBlockCreateOptions *
block_crypto_create_opts_init(QCryptoBlockFormat format,
QDict *opts,
Error **errp)
{
Visitor *v;
QCryptoBlockCreateOptions *ret = NULL;
Error *local_err = NULL;
ret = g_new0(QCryptoBlockCreateOptions, 1);
ret->format = format;
v = qobject_input_visitor_new_keyval(QOBJECT(opts));
visit_start_struct(v, NULL, NULL, 0, &local_err);
if (local_err) {
goto out;
}
switch (format) {
case Q_CRYPTO_BLOCK_FORMAT_LUKS:
visit_type_QCryptoBlockCreateOptionsLUKS_members(
v, &ret->u.luks, &local_err);
break;
case Q_CRYPTO_BLOCK_FORMAT_QCOW:
visit_type_QCryptoBlockOptionsQCow_members(
v, &ret->u.qcow, &local_err);
break;
default:
error_setg(&local_err, "Unsupported block format %d", format);
break;
}
if (!local_err) {
visit_check_struct(v, &local_err);
}
visit_end_struct(v, NULL);
out:
if (local_err) {
error_propagate(errp, local_err);
qapi_free_QCryptoBlockCreateOptions(ret);
ret = NULL;
}
visit_free(v);
return ret;
}
static int block_crypto_open_generic(QCryptoBlockFormat format,
QemuOptsList *opts_spec,
BlockDriverState *bs,
QDict *options,
int flags,
Error **errp)
{
BlockCrypto *crypto = bs->opaque;
QemuOpts *opts = NULL;
Error *local_err = NULL;
int ret = -EINVAL;
QCryptoBlockOpenOptions *open_opts = NULL;
unsigned int cflags = 0;
QDict *cryptoopts = NULL;
bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
false, errp);
if (!bs->file) {
return -EINVAL;
}
opts = qemu_opts_create(opts_spec, NULL, 0, &error_abort);
qemu_opts_absorb_qdict(opts, options, &local_err);
if (local_err) {
error_propagate(errp, local_err);
goto cleanup;
}
cryptoopts = qemu_opts_to_qdict(opts, NULL);
open_opts = block_crypto_open_opts_init(format, cryptoopts, errp);
if (!open_opts) {
goto cleanup;
}
if (flags & BDRV_O_NO_IO) {
cflags |= QCRYPTO_BLOCK_OPEN_NO_IO;
}
crypto->block = qcrypto_block_open(open_opts,
block_crypto_read_func,
bs,
cflags,
errp);
if (!crypto->block) {
ret = -EIO;
goto cleanup;
}
bs->encrypted = true;
ret = 0;
cleanup:
QDECREF(cryptoopts);
qapi_free_QCryptoBlockOpenOptions(open_opts);
return ret;
}
static int block_crypto_create_generic(QCryptoBlockFormat format,
const char *filename,
QemuOpts *opts,
Error **errp)
{
int ret = -EINVAL;
QCryptoBlockCreateOptions *create_opts = NULL;
QCryptoBlock *crypto = NULL;
struct BlockCryptoCreateData data = {
.size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
BDRV_SECTOR_SIZE),
.opts = opts,
.filename = filename,
};
QDict *cryptoopts;
cryptoopts = qemu_opts_to_qdict(opts, NULL);
create_opts = block_crypto_create_opts_init(format, cryptoopts, errp);
if (!create_opts) {
return -1;
}
crypto = qcrypto_block_create(create_opts,
block_crypto_init_func,
block_crypto_write_func,
&data,
errp);
if (!crypto) {
ret = -EIO;
goto cleanup;
}
ret = 0;
cleanup:
QDECREF(cryptoopts);
qcrypto_block_free(crypto);
blk_unref(data.blk);
qapi_free_QCryptoBlockCreateOptions(create_opts);
return ret;
}
static int block_crypto_truncate(BlockDriverState *bs, int64_t offset,
Error **errp)
{
BlockCrypto *crypto = bs->opaque;
size_t payload_offset =
qcrypto_block_get_payload_offset(crypto->block);
offset += payload_offset;
return bdrv_truncate(bs->file, offset, errp);
}
static void block_crypto_close(BlockDriverState *bs)
{
BlockCrypto *crypto = bs->opaque;
qcrypto_block_free(crypto->block);
}
#define BLOCK_CRYPTO_MAX_SECTORS 32
static coroutine_fn int
block_crypto_co_readv(BlockDriverState *bs, int64_t sector_num,
int remaining_sectors, QEMUIOVector *qiov)
{
BlockCrypto *crypto = bs->opaque;
int cur_nr_sectors; /* number of sectors in current iteration */
uint64_t bytes_done = 0;
uint8_t *cipher_data = NULL;
QEMUIOVector hd_qiov;
int ret = 0;
size_t payload_offset =
qcrypto_block_get_payload_offset(crypto->block) / 512;
qemu_iovec_init(&hd_qiov, qiov->niov);
/* Bounce buffer so we have a linear mem region for
* entire sector. XXX optimize so we avoid bounce
* buffer in case that qiov->niov == 1
*/
cipher_data =
qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_SECTORS * 512,
qiov->size));
if (cipher_data == NULL) {
ret = -ENOMEM;
goto cleanup;
}
while (remaining_sectors) {
cur_nr_sectors = remaining_sectors;
if (cur_nr_sectors > BLOCK_CRYPTO_MAX_SECTORS) {
cur_nr_sectors = BLOCK_CRYPTO_MAX_SECTORS;
}
qemu_iovec_reset(&hd_qiov);
qemu_iovec_add(&hd_qiov, cipher_data, cur_nr_sectors * 512);
ret = bdrv_co_readv(bs->file,
payload_offset + sector_num,
cur_nr_sectors, &hd_qiov);
if (ret < 0) {
goto cleanup;
}
if (qcrypto_block_decrypt(crypto->block,
sector_num,
cipher_data, cur_nr_sectors * 512,
NULL) < 0) {
ret = -EIO;
goto cleanup;
}
qemu_iovec_from_buf(qiov, bytes_done,
cipher_data, cur_nr_sectors * 512);
remaining_sectors -= cur_nr_sectors;
sector_num += cur_nr_sectors;
bytes_done += cur_nr_sectors * 512;
}
cleanup:
qemu_iovec_destroy(&hd_qiov);
qemu_vfree(cipher_data);
return ret;
}
static coroutine_fn int
block_crypto_co_writev(BlockDriverState *bs, int64_t sector_num,
int remaining_sectors, QEMUIOVector *qiov)
{
BlockCrypto *crypto = bs->opaque;
int cur_nr_sectors; /* number of sectors in current iteration */
uint64_t bytes_done = 0;
uint8_t *cipher_data = NULL;
QEMUIOVector hd_qiov;
int ret = 0;
size_t payload_offset =
qcrypto_block_get_payload_offset(crypto->block) / 512;
qemu_iovec_init(&hd_qiov, qiov->niov);
/* Bounce buffer so we have a linear mem region for
* entire sector. XXX optimize so we avoid bounce
* buffer in case that qiov->niov == 1
*/
cipher_data =
qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_SECTORS * 512,
qiov->size));
if (cipher_data == NULL) {
ret = -ENOMEM;
goto cleanup;
}
while (remaining_sectors) {
cur_nr_sectors = remaining_sectors;
if (cur_nr_sectors > BLOCK_CRYPTO_MAX_SECTORS) {
cur_nr_sectors = BLOCK_CRYPTO_MAX_SECTORS;
}
qemu_iovec_to_buf(qiov, bytes_done,
cipher_data, cur_nr_sectors * 512);
if (qcrypto_block_encrypt(crypto->block,
sector_num,
cipher_data, cur_nr_sectors * 512,
NULL) < 0) {
ret = -EIO;
goto cleanup;
}
qemu_iovec_reset(&hd_qiov);
qemu_iovec_add(&hd_qiov, cipher_data, cur_nr_sectors * 512);
ret = bdrv_co_writev(bs->file,
payload_offset + sector_num,
cur_nr_sectors, &hd_qiov);
if (ret < 0) {
goto cleanup;
}
remaining_sectors -= cur_nr_sectors;
sector_num += cur_nr_sectors;
bytes_done += cur_nr_sectors * 512;
}
cleanup:
qemu_iovec_destroy(&hd_qiov);
qemu_vfree(cipher_data);
return ret;
}
static int64_t block_crypto_getlength(BlockDriverState *bs)
{
BlockCrypto *crypto = bs->opaque;
int64_t len = bdrv_getlength(bs->file->bs);
ssize_t offset = qcrypto_block_get_payload_offset(crypto->block);
len -= offset;
return len;
}
static int block_crypto_probe_luks(const uint8_t *buf,
int buf_size,
const char *filename) {
return block_crypto_probe_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
buf, buf_size, filename);
}
static int block_crypto_open_luks(BlockDriverState *bs,
QDict *options,
int flags,
Error **errp)
{
return block_crypto_open_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
&block_crypto_runtime_opts_luks,
bs, options, flags, errp);
}
static int block_crypto_create_luks(const char *filename,
QemuOpts *opts,
Error **errp)
{
return block_crypto_create_generic(Q_CRYPTO_BLOCK_FORMAT_LUKS,
filename, opts, errp);
}
static int block_crypto_get_info_luks(BlockDriverState *bs,
BlockDriverInfo *bdi)
{
BlockDriverInfo subbdi;
int ret;
ret = bdrv_get_info(bs->file->bs, &subbdi);
if (ret != 0) {
return ret;
}
bdi->unallocated_blocks_are_zero = false;
bdi->can_write_zeroes_with_unmap = false;
bdi->cluster_size = subbdi.cluster_size;
return 0;
}
static ImageInfoSpecific *
block_crypto_get_specific_info_luks(BlockDriverState *bs)
{
BlockCrypto *crypto = bs->opaque;
ImageInfoSpecific *spec_info;
QCryptoBlockInfo *info;
info = qcrypto_block_get_info(crypto->block, NULL);
if (!info) {
return NULL;
}
if (info->format != Q_CRYPTO_BLOCK_FORMAT_LUKS) {
qapi_free_QCryptoBlockInfo(info);
return NULL;
}
spec_info = g_new(ImageInfoSpecific, 1);
spec_info->type = IMAGE_INFO_SPECIFIC_KIND_LUKS;
spec_info->u.luks.data = g_new(QCryptoBlockInfoLUKS, 1);
*spec_info->u.luks.data = info->u.luks;
/* Blank out pointers we've just stolen to avoid double free */
memset(&info->u.luks, 0, sizeof(info->u.luks));
qapi_free_QCryptoBlockInfo(info);
return spec_info;
}
BlockDriver bdrv_crypto_luks = {
.format_name = "luks",
.instance_size = sizeof(BlockCrypto),
.bdrv_probe = block_crypto_probe_luks,
.bdrv_open = block_crypto_open_luks,
.bdrv_close = block_crypto_close,
.bdrv_child_perm = bdrv_format_default_perms,
.bdrv_create = block_crypto_create_luks,
.bdrv_truncate = block_crypto_truncate,
.create_opts = &block_crypto_create_opts_luks,
.bdrv_co_readv = block_crypto_co_readv,
.bdrv_co_writev = block_crypto_co_writev,
.bdrv_getlength = block_crypto_getlength,
.bdrv_get_info = block_crypto_get_info_luks,
.bdrv_get_specific_info = block_crypto_get_specific_info_luks,
};
static void block_crypto_init(void)
{
bdrv_register(&bdrv_crypto_luks);
}
block_init(block_crypto_init);
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