qemu/crypto/block.c
Alberto Faria 757dda54b4 crypto: Make block callbacks return 0 on success
They currently return the value of their headerlen/buflen parameter on
success. Returning 0 instead makes it clear that short reads/writes are
not possible.

Signed-off-by: Alberto Faria <afaria@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20220609152744.3891847-5-afaria@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
2022-07-12 12:14:55 +02:00

476 lines
14 KiB
C

/*
* QEMU Crypto block device 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 2.1 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 "qapi/error.h"
#include "blockpriv.h"
#include "block-qcow.h"
#include "block-luks.h"
static const QCryptoBlockDriver *qcrypto_block_drivers[] = {
[Q_CRYPTO_BLOCK_FORMAT_QCOW] = &qcrypto_block_driver_qcow,
[Q_CRYPTO_BLOCK_FORMAT_LUKS] = &qcrypto_block_driver_luks,
};
bool qcrypto_block_has_format(QCryptoBlockFormat format,
const uint8_t *buf,
size_t len)
{
const QCryptoBlockDriver *driver;
if (format >= G_N_ELEMENTS(qcrypto_block_drivers) ||
!qcrypto_block_drivers[format]) {
return false;
}
driver = qcrypto_block_drivers[format];
return driver->has_format(buf, len);
}
QCryptoBlock *qcrypto_block_open(QCryptoBlockOpenOptions *options,
const char *optprefix,
QCryptoBlockReadFunc readfunc,
void *opaque,
unsigned int flags,
size_t n_threads,
Error **errp)
{
QCryptoBlock *block = g_new0(QCryptoBlock, 1);
block->format = options->format;
if (options->format >= G_N_ELEMENTS(qcrypto_block_drivers) ||
!qcrypto_block_drivers[options->format]) {
error_setg(errp, "Unsupported block driver %s",
QCryptoBlockFormat_str(options->format));
g_free(block);
return NULL;
}
block->driver = qcrypto_block_drivers[options->format];
if (block->driver->open(block, options, optprefix,
readfunc, opaque, flags, n_threads, errp) < 0)
{
g_free(block);
return NULL;
}
qemu_mutex_init(&block->mutex);
return block;
}
QCryptoBlock *qcrypto_block_create(QCryptoBlockCreateOptions *options,
const char *optprefix,
QCryptoBlockInitFunc initfunc,
QCryptoBlockWriteFunc writefunc,
void *opaque,
Error **errp)
{
QCryptoBlock *block = g_new0(QCryptoBlock, 1);
block->format = options->format;
if (options->format >= G_N_ELEMENTS(qcrypto_block_drivers) ||
!qcrypto_block_drivers[options->format]) {
error_setg(errp, "Unsupported block driver %s",
QCryptoBlockFormat_str(options->format));
g_free(block);
return NULL;
}
block->driver = qcrypto_block_drivers[options->format];
if (block->driver->create(block, options, optprefix, initfunc,
writefunc, opaque, errp) < 0) {
g_free(block);
return NULL;
}
qemu_mutex_init(&block->mutex);
return block;
}
static int 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 int 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 0;
}
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;
}
int qcrypto_block_amend_options(QCryptoBlock *block,
QCryptoBlockReadFunc readfunc,
QCryptoBlockWriteFunc writefunc,
void *opaque,
QCryptoBlockAmendOptions *options,
bool force,
Error **errp)
{
if (options->format != block->format) {
error_setg(errp,
"Cannot amend encryption format");
return -1;
}
if (!block->driver->amend) {
error_setg(errp,
"Crypto format %s doesn't support format options amendment",
QCryptoBlockFormat_str(block->format));
return -1;
}
return block->driver->amend(block,
readfunc,
writefunc,
opaque,
options,
force,
errp);
}
QCryptoBlockInfo *qcrypto_block_get_info(QCryptoBlock *block,
Error **errp)
{
QCryptoBlockInfo *info = g_new0(QCryptoBlockInfo, 1);
info->format = block->format;
if (block->driver->get_info &&
block->driver->get_info(block, info, errp) < 0) {
g_free(info);
return NULL;
}
return info;
}
int qcrypto_block_decrypt(QCryptoBlock *block,
uint64_t offset,
uint8_t *buf,
size_t len,
Error **errp)
{
return block->driver->decrypt(block, offset, buf, len, errp);
}
int qcrypto_block_encrypt(QCryptoBlock *block,
uint64_t offset,
uint8_t *buf,
size_t len,
Error **errp)
{
return block->driver->encrypt(block, offset, buf, len, errp);
}
QCryptoCipher *qcrypto_block_get_cipher(QCryptoBlock *block)
{
/* Ciphers should be accessed through pop/push method to be thread-safe.
* Better, they should not be accessed externally at all (note, that
* pop/push are static functions)
* This function is used only in test with one thread (it's safe to skip
* pop/push interface), so it's enough to assert it here:
*/
assert(block->n_ciphers <= 1);
return block->ciphers ? block->ciphers[0] : NULL;
}
static QCryptoCipher *qcrypto_block_pop_cipher(QCryptoBlock *block)
{
QCryptoCipher *cipher;
qemu_mutex_lock(&block->mutex);
assert(block->n_free_ciphers > 0);
block->n_free_ciphers--;
cipher = block->ciphers[block->n_free_ciphers];
qemu_mutex_unlock(&block->mutex);
return cipher;
}
static void qcrypto_block_push_cipher(QCryptoBlock *block,
QCryptoCipher *cipher)
{
qemu_mutex_lock(&block->mutex);
assert(block->n_free_ciphers < block->n_ciphers);
block->ciphers[block->n_free_ciphers] = cipher;
block->n_free_ciphers++;
qemu_mutex_unlock(&block->mutex);
}
int qcrypto_block_init_cipher(QCryptoBlock *block,
QCryptoCipherAlgorithm alg,
QCryptoCipherMode mode,
const uint8_t *key, size_t nkey,
size_t n_threads, Error **errp)
{
size_t i;
assert(!block->ciphers && !block->n_ciphers && !block->n_free_ciphers);
block->ciphers = g_new0(QCryptoCipher *, n_threads);
for (i = 0; i < n_threads; i++) {
block->ciphers[i] = qcrypto_cipher_new(alg, mode, key, nkey, errp);
if (!block->ciphers[i]) {
qcrypto_block_free_cipher(block);
return -1;
}
block->n_ciphers++;
block->n_free_ciphers++;
}
return 0;
}
void qcrypto_block_free_cipher(QCryptoBlock *block)
{
size_t i;
if (!block->ciphers) {
return;
}
assert(block->n_ciphers == block->n_free_ciphers);
for (i = 0; i < block->n_ciphers; i++) {
qcrypto_cipher_free(block->ciphers[i]);
}
g_free(block->ciphers);
block->ciphers = NULL;
block->n_ciphers = block->n_free_ciphers = 0;
}
QCryptoIVGen *qcrypto_block_get_ivgen(QCryptoBlock *block)
{
/* ivgen should be accessed under mutex. However, this function is used only
* in test with one thread, so it's enough to assert it here:
*/
assert(block->n_ciphers <= 1);
return block->ivgen;
}
QCryptoHashAlgorithm qcrypto_block_get_kdf_hash(QCryptoBlock *block)
{
return block->kdfhash;
}
uint64_t qcrypto_block_get_payload_offset(QCryptoBlock *block)
{
return block->payload_offset;
}
uint64_t qcrypto_block_get_sector_size(QCryptoBlock *block)
{
return block->sector_size;
}
void qcrypto_block_free(QCryptoBlock *block)
{
if (!block) {
return;
}
block->driver->cleanup(block);
qcrypto_block_free_cipher(block);
qcrypto_ivgen_free(block->ivgen);
qemu_mutex_destroy(&block->mutex);
g_free(block);
}
typedef int (*QCryptoCipherEncDecFunc)(QCryptoCipher *cipher,
const void *in,
void *out,
size_t len,
Error **errp);
static int do_qcrypto_block_cipher_encdec(QCryptoCipher *cipher,
size_t niv,
QCryptoIVGen *ivgen,
QemuMutex *ivgen_mutex,
int sectorsize,
uint64_t offset,
uint8_t *buf,
size_t len,
QCryptoCipherEncDecFunc func,
Error **errp)
{
g_autofree uint8_t *iv = niv ? g_new0(uint8_t, niv) : NULL;
int ret = -1;
uint64_t startsector = offset / sectorsize;
assert(QEMU_IS_ALIGNED(offset, sectorsize));
assert(QEMU_IS_ALIGNED(len, sectorsize));
while (len > 0) {
size_t nbytes;
if (niv) {
if (ivgen_mutex) {
qemu_mutex_lock(ivgen_mutex);
}
ret = qcrypto_ivgen_calculate(ivgen, startsector, iv, niv, errp);
if (ivgen_mutex) {
qemu_mutex_unlock(ivgen_mutex);
}
if (ret < 0) {
return -1;
}
if (qcrypto_cipher_setiv(cipher,
iv, niv,
errp) < 0) {
return -1;
}
}
nbytes = len > sectorsize ? sectorsize : len;
if (func(cipher, buf, buf, nbytes, errp) < 0) {
return -1;
}
startsector++;
buf += nbytes;
len -= nbytes;
}
return 0;
}
int qcrypto_block_cipher_decrypt_helper(QCryptoCipher *cipher,
size_t niv,
QCryptoIVGen *ivgen,
int sectorsize,
uint64_t offset,
uint8_t *buf,
size_t len,
Error **errp)
{
return do_qcrypto_block_cipher_encdec(cipher, niv, ivgen, NULL, sectorsize,
offset, buf, len,
qcrypto_cipher_decrypt, errp);
}
int qcrypto_block_cipher_encrypt_helper(QCryptoCipher *cipher,
size_t niv,
QCryptoIVGen *ivgen,
int sectorsize,
uint64_t offset,
uint8_t *buf,
size_t len,
Error **errp)
{
return do_qcrypto_block_cipher_encdec(cipher, niv, ivgen, NULL, sectorsize,
offset, buf, len,
qcrypto_cipher_encrypt, errp);
}
int qcrypto_block_decrypt_helper(QCryptoBlock *block,
int sectorsize,
uint64_t offset,
uint8_t *buf,
size_t len,
Error **errp)
{
int ret;
QCryptoCipher *cipher = qcrypto_block_pop_cipher(block);
ret = do_qcrypto_block_cipher_encdec(cipher, block->niv, block->ivgen,
&block->mutex, sectorsize, offset, buf,
len, qcrypto_cipher_decrypt, errp);
qcrypto_block_push_cipher(block, cipher);
return ret;
}
int qcrypto_block_encrypt_helper(QCryptoBlock *block,
int sectorsize,
uint64_t offset,
uint8_t *buf,
size_t len,
Error **errp)
{
int ret;
QCryptoCipher *cipher = qcrypto_block_pop_cipher(block);
ret = do_qcrypto_block_cipher_encdec(cipher, block->niv, block->ivgen,
&block->mutex, sectorsize, offset, buf,
len, qcrypto_cipher_encrypt, errp);
qcrypto_block_push_cipher(block, cipher);
return ret;
}