qemu/block/crypto.c
Max Reitz e61a28a9b6 block: Let format drivers pass @exact
When truncating a format node, the @exact parameter is generally handled
simply by virtue of the format storing the new size in the image
metadata.  Such formats do not need to pass on the parameter to their
file nodes.

There are exceptions, though:
- raw and crypto cannot store the image size, and thus must pass on
  @exact.

- When using qcow2 with an external data file, it just makes sense to
  keep its size in sync with the qcow2 virtual disk (because the
  external data file is the virtual disk).  Therefore, we should pass
  @exact when truncating it.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20190918095144.955-7-mreitz@redhat.com
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2019-10-28 12:05:30 +01:00

685 lines
19 KiB
C

/*
* 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 "block/qdict.h"
#include "sysemu/block-backend.h"
#include "crypto/block.h"
#include "qapi/opts-visitor.h"
#include "qapi/qapi-visit-crypto.h"
#include "qapi/qobject-input-visitor.h"
#include "qapi/error.h"
#include "qemu/module.h"
#include "qemu/option.h"
#include "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 {
BlockBackend *blk;
uint64_t size;
PreallocMode prealloc;
};
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;
if (data->size > INT64_MAX || headerlen > INT64_MAX - data->size) {
error_setg(errp, "The requested file size is too large");
return -EFBIG;
}
/* 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
*/
return blk_truncate(data->blk, data->size + headerlen, false,
data->prealloc, errp);
}
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(QDict *opts, Error **errp)
{
Visitor *v;
QCryptoBlockOpenOptions *ret;
v = qobject_input_visitor_new_flat_confused(opts, errp);
if (!v) {
return NULL;
}
visit_type_QCryptoBlockOpenOptions(v, NULL, &ret, errp);
visit_free(v);
return ret;
}
QCryptoBlockCreateOptions *
block_crypto_create_opts_init(QDict *opts, Error **errp)
{
Visitor *v;
QCryptoBlockCreateOptions *ret;
v = qobject_input_visitor_new_flat_confused(opts, errp);
if (!v) {
return NULL;
}
visit_type_QCryptoBlockCreateOptions(v, NULL, &ret, errp);
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;
}
bs->supported_write_flags = BDRV_REQ_FUA &
bs->file->bs->supported_write_flags;
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);
qdict_put_str(cryptoopts, "format", QCryptoBlockFormat_str(format));
open_opts = block_crypto_open_opts_init(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, NULL,
block_crypto_read_func,
bs,
cflags,
1,
errp);
if (!crypto->block) {
ret = -EIO;
goto cleanup;
}
bs->encrypted = true;
ret = 0;
cleanup:
qobject_unref(cryptoopts);
qapi_free_QCryptoBlockOpenOptions(open_opts);
return ret;
}
static int block_crypto_co_create_generic(BlockDriverState *bs,
int64_t size,
QCryptoBlockCreateOptions *opts,
PreallocMode prealloc,
Error **errp)
{
int ret;
BlockBackend *blk;
QCryptoBlock *crypto = NULL;
struct BlockCryptoCreateData data;
blk = blk_new(bdrv_get_aio_context(bs),
BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL);
ret = blk_insert_bs(blk, bs, errp);
if (ret < 0) {
goto cleanup;
}
if (prealloc == PREALLOC_MODE_METADATA) {
prealloc = PREALLOC_MODE_OFF;
}
data = (struct BlockCryptoCreateData) {
.blk = blk,
.size = size,
.prealloc = prealloc,
};
crypto = qcrypto_block_create(opts, NULL,
block_crypto_init_func,
block_crypto_write_func,
&data,
errp);
if (!crypto) {
ret = -EIO;
goto cleanup;
}
ret = 0;
cleanup:
qcrypto_block_free(crypto);
blk_unref(blk);
return ret;
}
static int coroutine_fn
block_crypto_co_truncate(BlockDriverState *bs, int64_t offset, bool exact,
PreallocMode prealloc, Error **errp)
{
BlockCrypto *crypto = bs->opaque;
uint64_t payload_offset =
qcrypto_block_get_payload_offset(crypto->block);
if (payload_offset > INT64_MAX - offset) {
error_setg(errp, "The requested file size is too large");
return -EFBIG;
}
offset += payload_offset;
return bdrv_co_truncate(bs->file, offset, exact, prealloc, errp);
}
static void block_crypto_close(BlockDriverState *bs)
{
BlockCrypto *crypto = bs->opaque;
qcrypto_block_free(crypto->block);
}
static int block_crypto_reopen_prepare(BDRVReopenState *state,
BlockReopenQueue *queue, Error **errp)
{
/* nothing needs checking */
return 0;
}
/*
* 1 MB bounce buffer gives good performance / memory tradeoff
* when using cache=none|directsync.
*/
#define BLOCK_CRYPTO_MAX_IO_SIZE (1024 * 1024)
static coroutine_fn int
block_crypto_co_preadv(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
BlockCrypto *crypto = bs->opaque;
uint64_t cur_bytes; /* number of bytes in current iteration */
uint64_t bytes_done = 0;
uint8_t *cipher_data = NULL;
QEMUIOVector hd_qiov;
int ret = 0;
uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
uint64_t payload_offset = qcrypto_block_get_payload_offset(crypto->block);
assert(!flags);
assert(payload_offset < INT64_MAX);
assert(QEMU_IS_ALIGNED(offset, sector_size));
assert(QEMU_IS_ALIGNED(bytes, sector_size));
qemu_iovec_init(&hd_qiov, qiov->niov);
/* Bounce buffer because we don't wish to expose cipher text
* in qiov which points to guest memory.
*/
cipher_data =
qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_IO_SIZE,
qiov->size));
if (cipher_data == NULL) {
ret = -ENOMEM;
goto cleanup;
}
while (bytes) {
cur_bytes = MIN(bytes, BLOCK_CRYPTO_MAX_IO_SIZE);
qemu_iovec_reset(&hd_qiov);
qemu_iovec_add(&hd_qiov, cipher_data, cur_bytes);
ret = bdrv_co_preadv(bs->file, payload_offset + offset + bytes_done,
cur_bytes, &hd_qiov, 0);
if (ret < 0) {
goto cleanup;
}
if (qcrypto_block_decrypt(crypto->block, offset + bytes_done,
cipher_data, cur_bytes, NULL) < 0) {
ret = -EIO;
goto cleanup;
}
qemu_iovec_from_buf(qiov, bytes_done, cipher_data, cur_bytes);
bytes -= cur_bytes;
bytes_done += cur_bytes;
}
cleanup:
qemu_iovec_destroy(&hd_qiov);
qemu_vfree(cipher_data);
return ret;
}
static coroutine_fn int
block_crypto_co_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes,
QEMUIOVector *qiov, int flags)
{
BlockCrypto *crypto = bs->opaque;
uint64_t cur_bytes; /* number of bytes in current iteration */
uint64_t bytes_done = 0;
uint8_t *cipher_data = NULL;
QEMUIOVector hd_qiov;
int ret = 0;
uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
uint64_t payload_offset = qcrypto_block_get_payload_offset(crypto->block);
assert(!(flags & ~BDRV_REQ_FUA));
assert(payload_offset < INT64_MAX);
assert(QEMU_IS_ALIGNED(offset, sector_size));
assert(QEMU_IS_ALIGNED(bytes, sector_size));
qemu_iovec_init(&hd_qiov, qiov->niov);
/* Bounce buffer because we're not permitted to touch
* contents of qiov - it points to guest memory.
*/
cipher_data =
qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_IO_SIZE,
qiov->size));
if (cipher_data == NULL) {
ret = -ENOMEM;
goto cleanup;
}
while (bytes) {
cur_bytes = MIN(bytes, BLOCK_CRYPTO_MAX_IO_SIZE);
qemu_iovec_to_buf(qiov, bytes_done, cipher_data, cur_bytes);
if (qcrypto_block_encrypt(crypto->block, offset + bytes_done,
cipher_data, cur_bytes, NULL) < 0) {
ret = -EIO;
goto cleanup;
}
qemu_iovec_reset(&hd_qiov);
qemu_iovec_add(&hd_qiov, cipher_data, cur_bytes);
ret = bdrv_co_pwritev(bs->file, payload_offset + offset + bytes_done,
cur_bytes, &hd_qiov, flags);
if (ret < 0) {
goto cleanup;
}
bytes -= cur_bytes;
bytes_done += cur_bytes;
}
cleanup:
qemu_iovec_destroy(&hd_qiov);
qemu_vfree(cipher_data);
return ret;
}
static void block_crypto_refresh_limits(BlockDriverState *bs, Error **errp)
{
BlockCrypto *crypto = bs->opaque;
uint64_t sector_size = qcrypto_block_get_sector_size(crypto->block);
bs->bl.request_alignment = sector_size; /* No sub-sector I/O */
}
static int64_t block_crypto_getlength(BlockDriverState *bs)
{
BlockCrypto *crypto = bs->opaque;
int64_t len = bdrv_getlength(bs->file->bs);
uint64_t offset = qcrypto_block_get_payload_offset(crypto->block);
assert(offset < INT64_MAX);
if (offset > len) {
return -EIO;
}
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 coroutine_fn
block_crypto_co_create_luks(BlockdevCreateOptions *create_options, Error **errp)
{
BlockdevCreateOptionsLUKS *luks_opts;
BlockDriverState *bs = NULL;
QCryptoBlockCreateOptions create_opts;
PreallocMode preallocation = PREALLOC_MODE_OFF;
int ret;
assert(create_options->driver == BLOCKDEV_DRIVER_LUKS);
luks_opts = &create_options->u.luks;
bs = bdrv_open_blockdev_ref(luks_opts->file, errp);
if (bs == NULL) {
return -EIO;
}
create_opts = (QCryptoBlockCreateOptions) {
.format = Q_CRYPTO_BLOCK_FORMAT_LUKS,
.u.luks = *qapi_BlockdevCreateOptionsLUKS_base(luks_opts),
};
if (luks_opts->has_preallocation) {
preallocation = luks_opts->preallocation;
}
ret = block_crypto_co_create_generic(bs, luks_opts->size, &create_opts,
preallocation, errp);
if (ret < 0) {
goto fail;
}
ret = 0;
fail:
bdrv_unref(bs);
return ret;
}
static int coroutine_fn block_crypto_co_create_opts_luks(const char *filename,
QemuOpts *opts,
Error **errp)
{
QCryptoBlockCreateOptions *create_opts = NULL;
BlockDriverState *bs = NULL;
QDict *cryptoopts;
PreallocMode prealloc;
char *buf = NULL;
int64_t size;
int ret;
Error *local_err = NULL;
/* Parse options */
size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
buf = qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC);
prealloc = qapi_enum_parse(&PreallocMode_lookup, buf,
PREALLOC_MODE_OFF, &local_err);
g_free(buf);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
cryptoopts = qemu_opts_to_qdict_filtered(opts, NULL,
&block_crypto_create_opts_luks,
true);
qdict_put_str(cryptoopts, "format", "luks");
create_opts = block_crypto_create_opts_init(cryptoopts, errp);
if (!create_opts) {
ret = -EINVAL;
goto fail;
}
/* Create protocol layer */
ret = bdrv_create_file(filename, opts, errp);
if (ret < 0) {
goto fail;
}
bs = bdrv_open(filename, NULL, NULL,
BDRV_O_RDWR | BDRV_O_RESIZE | BDRV_O_PROTOCOL, errp);
if (!bs) {
ret = -EINVAL;
goto fail;
}
/* Create format layer */
ret = block_crypto_co_create_generic(bs, size, create_opts, prealloc, errp);
if (ret < 0) {
goto fail;
}
ret = 0;
fail:
bdrv_unref(bs);
qapi_free_QCryptoBlockCreateOptions(create_opts);
qobject_unref(cryptoopts);
return ret;
}
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->cluster_size = subbdi.cluster_size;
return 0;
}
static ImageInfoSpecific *
block_crypto_get_specific_info_luks(BlockDriverState *bs, Error **errp)
{
BlockCrypto *crypto = bs->opaque;
ImageInfoSpecific *spec_info;
QCryptoBlockInfo *info;
info = qcrypto_block_get_info(crypto->block, errp);
if (!info) {
return NULL;
}
assert(info->format == Q_CRYPTO_BLOCK_FORMAT_LUKS);
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;
}
static const char *const block_crypto_strong_runtime_opts[] = {
BLOCK_CRYPTO_OPT_LUKS_KEY_SECRET,
NULL
};
static 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,
/* This driver doesn't modify LUKS metadata except when creating image.
* Allow share-rw=on as a special case. */
.bdrv_child_perm = bdrv_filter_default_perms,
.bdrv_co_create = block_crypto_co_create_luks,
.bdrv_co_create_opts = block_crypto_co_create_opts_luks,
.bdrv_co_truncate = block_crypto_co_truncate,
.create_opts = &block_crypto_create_opts_luks,
.bdrv_reopen_prepare = block_crypto_reopen_prepare,
.bdrv_refresh_limits = block_crypto_refresh_limits,
.bdrv_co_preadv = block_crypto_co_preadv,
.bdrv_co_pwritev = block_crypto_co_pwritev,
.bdrv_getlength = block_crypto_getlength,
.bdrv_get_info = block_crypto_get_info_luks,
.bdrv_get_specific_info = block_crypto_get_specific_info_luks,
.strong_runtime_opts = block_crypto_strong_runtime_opts,
};
static void block_crypto_init(void)
{
bdrv_register(&bdrv_crypto_luks);
}
block_init(block_crypto_init);