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luks: extract qcrypto_block_calculate_payload_offset()

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The qcow2 .bdrv_measure() code calculates the crypto payload offset.
This logic really belongs in crypto/block.c where it can be reused by
other image formats.

The "luks" block driver will need this same logic in order to implement
.bdrv_measure(), so extract the qcrypto_block_calculate_payload_offset()
function now.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200221112522.1497712-2-stefanha@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2020-02-21 11:25:19 +00:00 committed by Max Reitz
parent ba29883206
commit 6d49d3a859
3 changed files with 77 additions and 55 deletions
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74
block/qcow2.c
View File

@ -4608,60 +4608,6 @@ static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs)
return ret;
}
static ssize_t qcow2_measure_crypto_hdr_init_func(QCryptoBlock *block,
size_t headerlen, void *opaque, Error **errp)
{
size_t *headerlenp = opaque;
/* Stash away the payload size */
*headerlenp = headerlen;
return 0;
}
static ssize_t qcow2_measure_crypto_hdr_write_func(QCryptoBlock *block,
size_t offset, const uint8_t *buf, size_t buflen,
void *opaque, Error **errp)
{
/* Discard the bytes, we're not actually writing to an image */
return buflen;
}
/* Determine the number of bytes for the LUKS payload */
static bool qcow2_measure_luks_headerlen(QemuOpts *opts, size_t *len,
Error **errp)
{
QDict *opts_qdict;
QDict *cryptoopts_qdict;
QCryptoBlockCreateOptions *cryptoopts;
QCryptoBlock *crypto;
/* Extract "encrypt." options into a qdict */
opts_qdict = qemu_opts_to_qdict(opts, NULL);
qdict_extract_subqdict(opts_qdict, &cryptoopts_qdict, "encrypt.");
qobject_unref(opts_qdict);
/* Build QCryptoBlockCreateOptions object from qdict */
qdict_put_str(cryptoopts_qdict, "format", "luks");
cryptoopts = block_crypto_create_opts_init(cryptoopts_qdict, errp);
qobject_unref(cryptoopts_qdict);
if (!cryptoopts) {
return false;
}
/* Fake LUKS creation in order to determine the payload size */
crypto = qcrypto_block_create(cryptoopts, "encrypt.",
qcow2_measure_crypto_hdr_init_func,
qcow2_measure_crypto_hdr_write_func,
len, errp);
qapi_free_QCryptoBlockCreateOptions(cryptoopts);
if (!crypto) {
return false;
}
qcrypto_block_free(crypto);
return true;
}
static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs,
Error **errp)
{
@ -4712,9 +4658,27 @@ static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs,
g_free(optstr);
if (has_luks) {
g_autoptr(QCryptoBlockCreateOptions) create_opts = NULL;
QDict *opts_qdict;
QDict *cryptoopts;
size_t headerlen;
if (!qcow2_measure_luks_headerlen(opts, &headerlen, &local_err)) {
opts_qdict = qemu_opts_to_qdict(opts, NULL);
qdict_extract_subqdict(opts_qdict, &cryptoopts, "encrypt.");
qobject_unref(opts_qdict);
qdict_put_str(cryptoopts, "format", "luks");
create_opts = block_crypto_create_opts_init(cryptoopts, errp);
qobject_unref(cryptoopts);
if (!create_opts) {
goto err;
}
if (!qcrypto_block_calculate_payload_offset(create_opts,
"encrypt.",
&headerlen,
&local_err)) {
goto err;
}

36
crypto/block.c
View File

@ -115,6 +115,42 @@ QCryptoBlock *qcrypto_block_create(QCryptoBlockCreateOptions *options,
}
static ssize_t qcrypto_block_headerlen_hdr_init_func(QCryptoBlock *block,
size_t headerlen, void *opaque, Error **errp)
{
size_t *headerlenp = opaque;
/* Stash away the payload size */
*headerlenp = headerlen;
return 0;
}
static ssize_t qcrypto_block_headerlen_hdr_write_func(QCryptoBlock *block,
size_t offset, const uint8_t *buf, size_t buflen,
void *opaque, Error **errp)
{
/* Discard the bytes, we're not actually writing to an image */
return buflen;
}
bool
qcrypto_block_calculate_payload_offset(QCryptoBlockCreateOptions *create_opts,
const char *optprefix,
size_t *len,
Error **errp)
{
/* Fake LUKS creation in order to determine the payload size */
g_autoptr(QCryptoBlock) crypto =
qcrypto_block_create(create_opts, optprefix,
qcrypto_block_headerlen_hdr_init_func,
qcrypto_block_headerlen_hdr_write_func,
len, errp);
return crypto != NULL;
}
QCryptoBlockInfo *qcrypto_block_get_info(QCryptoBlock *block,
Error **errp)
{

22
include/crypto/block.h
View File

@ -145,6 +145,26 @@ QCryptoBlock *qcrypto_block_create(QCryptoBlockCreateOptions *options,
Error **errp);
/**
* qcrypto_block_calculate_payload_offset:
* @create_opts: the encryption options
* @optprefix: name prefix for options
* @len: output for number of header bytes before payload
* @errp: pointer to a NULL-initialized error object
*
* Calculate the number of header bytes before the payload in an encrypted
* storage volume. The header is an area before the payload that is reserved
* for encryption metadata.
*
* Returns: true on success, false on error
*/
bool
qcrypto_block_calculate_payload_offset(QCryptoBlockCreateOptions *create_opts,
const char *optprefix,
size_t *len,
Error **errp);
/**
* qcrypto_block_get_info:
* @block: the block encryption object
@ -269,5 +289,7 @@ uint64_t qcrypto_block_get_sector_size(QCryptoBlock *block);
void qcrypto_block_free(QCryptoBlock *block);
G_DEFINE_AUTOPTR_CLEANUP_FUNC(QCryptoBlock, qcrypto_block_free)
G_DEFINE_AUTOPTR_CLEANUP_FUNC(QCryptoBlockCreateOptions,
qapi_free_QCryptoBlockCreateOptions)
#endif /* QCRYPTO_BLOCK_H */