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qemu/block/crypto.c
Eric Blake 5d72c68b49 qcow2: Expose bitmaps' size during measure 
It's useful to know how much space can be occupied by qcow2 persistent
bitmaps, even though such metadata is unrelated to the guest-visible
data.  Report this value as an additional QMP field, present when
measuring an existing image and output format that both support
bitmaps.  Update iotest 178 and 190 to updated output, as well as new
coverage in 190 demonstrating non-zero values made possible with the
recently-added qemu-img bitmap command (see 3b51ab4b).

The new 'bitmaps size:' field is displayed automatically as part of
'qemu-img measure' any time it is present in QMP (that is, any time
both the source image being measured and destination format support
bitmaps, even if the measurement is 0 because there are no bitmaps
present).  If the field is absent, it means that no bitmaps can be
copied (source, destination, or both lack bitmaps, including when
measuring based on size rather than on a source image).  This behavior
is compatible with an upcoming patch adding 'qemu-img convert
--bitmaps': that command will fail in the same situations where this
patch omits the field.

The addition of a new field demonstrates why we should always
zero-initialize qapi C structs; while the qcow2 driver still fully
populates all fields, the raw and crypto drivers had to be tweaked to
avoid uninitialized data.

Consideration was also given towards having a 'qemu-img measure
--bitmaps' which errors out when bitmaps are not possible, and
otherwise sums the bitmaps into the existing allocation totals rather
than displaying as a separate field, as a potential convenience
factor.  But this was ultimately decided to be more complexity than
necessary when the QMP interface was sufficient enough with bitmaps
remaining a separate field.

See also: https://bugzilla.redhat.com/1779904

Reported-by: Nir Soffer <nsoffer@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200521192137.1120211-3-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2020-05-28 13:16:16 -05:00

785 lines
22 KiB
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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 "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 "qemu/cutils.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;
Error *local_error = NULL;
int ret;
if (data->size > INT64_MAX || headerlen > INT64_MAX - data->size) {
ret = -EFBIG;
goto error;
}
/* 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
*/
ret = blk_truncate(data->blk, data->size + headerlen, false,
data->prealloc, 0, &local_error);
if (ret >= 0) {
return ret;
}
error:
if (ret == -EFBIG) {
/* Replace the error message with a better one */
error_free(local_error);
error_setg(errp, "The requested file size is too large");
} else {
error_propagate(errp, local_error);
}
return ret;
}
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_of_bds,
BDRV_CHILD_IMAGE, 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_with_bs(bs, BLK_PERM_WRITE | BLK_PERM_RESIZE, BLK_PERM_ALL,
errp);
if (!blk) {
ret = -EPERM;
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, BdrvRequestFlags flags,
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, 0, 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 BlockMeasureInfo *block_crypto_measure(QemuOpts *opts,
BlockDriverState *in_bs,
Error **errp)
{
g_autoptr(QCryptoBlockCreateOptions) create_opts = NULL;
Error *local_err = NULL;
BlockMeasureInfo *info;
uint64_t size;
size_t luks_payload_size;
QDict *cryptoopts;
/*
* Preallocation mode doesn't affect size requirements but we must consume
* the option.
*/
g_free(qemu_opt_get_del(opts, BLOCK_OPT_PREALLOC));
size = qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0);
if (in_bs) {
int64_t ssize = bdrv_getlength(in_bs);
if (ssize < 0) {
error_setg_errno(&local_err, -ssize,
"Unable to get image virtual_size");
goto err;
}
size = ssize;
}
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, &local_err);
qobject_unref(cryptoopts);
if (!create_opts) {
goto err;
}
if (!qcrypto_block_calculate_payload_offset(create_opts, NULL,
&luks_payload_size,
&local_err)) {
goto err;
}
/*
* Unallocated blocks are still encrypted so allocation status makes no
* difference to the file size.
*/
info = g_new0(BlockMeasureInfo, 1);
info->fully_allocated = luks_payload_size + size;
info->required = luks_payload_size + size;
return info;
err:
error_propagate(errp, local_err);
return NULL;
}
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(BlockDriver *drv,
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:
/*
* If an error occurred, delete 'filename'. Even if the file existed
* beforehand, it has been truncated and corrupted in the process.
*/
if (ret && bs) {
Error *local_delete_err = NULL;
int r_del = bdrv_co_delete_file(bs, &local_delete_err);
/*
* ENOTSUP will happen if the block driver doesn't support
* the 'bdrv_co_delete_file' interface. This is a predictable
* scenario and shouldn't be reported back to the user.
*/
if ((r_del < 0) && (r_del != -ENOTSUP)) {
error_report_err(local_delete_err);
}
}
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_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_measure = block_crypto_measure,
.bdrv_get_info = block_crypto_get_info_luks,
.bdrv_get_specific_info = block_crypto_get_specific_info_luks,
.is_format = true,
.strong_runtime_opts = block_crypto_strong_runtime_opts,
};
static void block_crypto_init(void)
{
bdrv_register(&bdrv_crypto_luks);
}
block_init(block_crypto_init);
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