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crypto: Assume blocksize is a power of 2 

The check in the encode/decode path using full division has a
noticeable amount of overhead.  By asserting the blocksize is
a power of 2, we can reduce this check to a mask.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Richard Henderson 2020-08-28 10:05:08 -07:00 committed by Daniel P. Berrangé
parent ca04c3cf15
commit eba29771c0
4 changed files with 9 additions and 6 deletions
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4
crypto/cipher-builtin.c
View File

@ -484,7 +484,7 @@ qcrypto_builtin_cipher_encrypt(QCryptoCipher *cipher,
{
QCryptoCipherBuiltin *ctxt = cipher->opaque;
if (len % ctxt->blocksize) {
if (len & (ctxt->blocksize - 1)) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctxt->blocksize);
return -1;
@ -503,7 +503,7 @@ qcrypto_builtin_cipher_decrypt(QCryptoCipher *cipher,
{
QCryptoCipherBuiltin *ctxt = cipher->opaque;
if (len % ctxt->blocksize) {
if (len & (ctxt->blocksize - 1)) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctxt->blocksize);
return -1;

5
crypto/cipher-gcrypt.c
View File

@ -245,6 +245,7 @@ static QCryptoCipherGcrypt *qcrypto_cipher_ctx_new(QCryptoCipherAlgorithm alg,
g_assert_not_reached();
}
}
g_assert(is_power_of_2(ctx->blocksize));
#ifdef CONFIG_QEMU_PRIVATE_XTS
if (mode == QCRYPTO_CIPHER_MODE_XTS) {
@ -305,7 +306,7 @@ qcrypto_gcrypt_cipher_encrypt(QCryptoCipher *cipher,
QCryptoCipherGcrypt *ctx = cipher->opaque;
gcry_error_t err;
if (len % ctx->blocksize) {
if (len & (ctx->blocksize - 1)) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctx->blocksize);
return -1;
@ -344,7 +345,7 @@ qcrypto_gcrypt_cipher_decrypt(QCryptoCipher *cipher,
QCryptoCipherGcrypt *ctx = cipher->opaque;
gcry_error_t err;
if (len % ctx->blocksize) {
if (len & (ctx->blocksize - 1)) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctx->blocksize);
return -1;

5
crypto/cipher-nettle.c
View File

@ -576,6 +576,7 @@ static QCryptoCipherNettle *qcrypto_cipher_ctx_new(QCryptoCipherAlgorithm alg,
QCryptoCipherAlgorithm_str(alg));
goto error;
}
g_assert(is_power_of_2(ctx->blocksize));
if (mode == QCRYPTO_CIPHER_MODE_XTS &&
ctx->blocksize != XTS_BLOCK_SIZE) {
@ -613,7 +614,7 @@ qcrypto_nettle_cipher_encrypt(QCryptoCipher *cipher,
{
QCryptoCipherNettle *ctx = cipher->opaque;
if (len % ctx->blocksize) {
if (len & (ctx->blocksize - 1)) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctx->blocksize);
return -1;
@ -666,7 +667,7 @@ qcrypto_nettle_cipher_decrypt(QCryptoCipher *cipher,
{
QCryptoCipherNettle *ctx = cipher->opaque;
if (len % ctx->blocksize) {
if (len & (ctx->blocksize - 1)) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctx->blocksize);
return -1;

1
crypto/cipher.c
View File

@ -19,6 +19,7 @@
*/
#include "qemu/osdep.h"
#include "qemu/host-utils.h"
#include "qapi/error.h"
#include "crypto/cipher.h"
#include "cipherpriv.h"