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crypto: delete built-in XTS cipher mode support

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The built-in AES+XTS implementation is used for the LUKS encryption
When building system emulators it is reasonable to expect that an
external crypto library is being used instead. The performance of the
builtin XTS implementation is terrible as it has no CPU acceleration
support. It is thus not worth keeping a home grown XTS implementation
for the built-in cipher backend.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrangé 2021-07-02 17:00:32 +01:00
parent 21407ddf96
commit 6801404429
3 changed files with 6 additions and 67 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
crypto/cipher-builtin.c.inc
View File

@ -19,7 +19,6 @@
*/
#include "crypto/aes.h"
#include "crypto/xts.h"
typedef struct QCryptoCipherBuiltinAESContext QCryptoCipherBuiltinAESContext;
struct QCryptoCipherBuiltinAESContext {
@ -31,7 +30,6 @@ typedef struct QCryptoCipherBuiltinAES QCryptoCipherBuiltinAES;
struct QCryptoCipherBuiltinAES {
QCryptoCipher base;
QCryptoCipherBuiltinAESContext key;
QCryptoCipherBuiltinAESContext key_tweak;
uint8_t iv[AES_BLOCK_SIZE];
};
@ -193,39 +191,6 @@ static int qcrypto_cipher_aes_decrypt_cbc(QCryptoCipher *cipher,
return 0;
}
static int qcrypto_cipher_aes_encrypt_xts(QCryptoCipher *cipher,
const void *in, void *out,
size_t len, Error **errp)
{
QCryptoCipherBuiltinAES *ctx
= container_of(cipher, QCryptoCipherBuiltinAES, base);
if (!qcrypto_length_check(len, AES_BLOCK_SIZE, errp)) {
return -1;
}
xts_encrypt(&ctx->key, &ctx->key_tweak,
do_aes_encrypt_ecb, do_aes_decrypt_ecb,
ctx->iv, len, out, in);
return 0;
}
static int qcrypto_cipher_aes_decrypt_xts(QCryptoCipher *cipher,
const void *in, void *out,
size_t len, Error **errp)
{
QCryptoCipherBuiltinAES *ctx
= container_of(cipher, QCryptoCipherBuiltinAES, base);
if (!qcrypto_length_check(len, AES_BLOCK_SIZE, errp)) {
return -1;
}
xts_decrypt(&ctx->key, &ctx->key_tweak,
do_aes_encrypt_ecb, do_aes_decrypt_ecb,
ctx->iv, len, out, in);
return 0;
}
static int qcrypto_cipher_aes_setiv(QCryptoCipher *cipher, const uint8_t *iv,
size_t niv, Error **errp)
{
@ -256,14 +221,6 @@ static const struct QCryptoCipherDriver qcrypto_cipher_aes_driver_cbc = {
.cipher_free = qcrypto_cipher_ctx_free,
};
static const struct QCryptoCipherDriver qcrypto_cipher_aes_driver_xts = {
.cipher_encrypt = qcrypto_cipher_aes_encrypt_xts,
.cipher_decrypt = qcrypto_cipher_aes_decrypt_xts,
.cipher_setiv = qcrypto_cipher_aes_setiv,
.cipher_free = qcrypto_cipher_ctx_free,
};
bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg,
QCryptoCipherMode mode)
{
@ -274,7 +231,6 @@ bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg,
switch (mode) {
case QCRYPTO_CIPHER_MODE_ECB:
case QCRYPTO_CIPHER_MODE_CBC:
case QCRYPTO_CIPHER_MODE_XTS:
return true;
default:
return false;
@ -310,9 +266,6 @@ static QCryptoCipher *qcrypto_cipher_ctx_new(QCryptoCipherAlgorithm alg,
case QCRYPTO_CIPHER_MODE_CBC:
drv = &qcrypto_cipher_aes_driver_cbc;
break;
case QCRYPTO_CIPHER_MODE_XTS:
drv = &qcrypto_cipher_aes_driver_xts;
break;
default:
goto bad_mode;
}
@ -320,19 +273,6 @@ static QCryptoCipher *qcrypto_cipher_ctx_new(QCryptoCipherAlgorithm alg,
ctx = g_new0(QCryptoCipherBuiltinAES, 1);
ctx->base.driver = drv;
if (mode == QCRYPTO_CIPHER_MODE_XTS) {
nkey /= 2;
if (AES_set_encrypt_key(key + nkey, nkey * 8,
&ctx->key_tweak.enc)) {
error_setg(errp, "Failed to set encryption key");
goto error;
}
if (AES_set_decrypt_key(key + nkey, nkey * 8,
&ctx->key_tweak.dec)) {
error_setg(errp, "Failed to set decryption key");
goto error;
}
}
if (AES_set_encrypt_key(key, nkey * 8, &ctx->key.enc)) {
error_setg(errp, "Failed to set encryption key");
goto error;

6
crypto/meson.build
View File

@ -23,14 +23,14 @@ crypto_ss.add(files(
if nettle.found()
crypto_ss.add(nettle, files('hash-nettle.c', 'hmac-nettle.c', 'pbkdf-nettle.c'))
if xts == 'private'
crypto_ss.add(files('xts.c'))
endif
elif gcrypt.found()
crypto_ss.add(gcrypt, files('hash-gcrypt.c', 'hmac-gcrypt.c', 'pbkdf-gcrypt.c'))
else
crypto_ss.add(files('hash-glib.c', 'hmac-glib.c', 'pbkdf-stub.c'))
endif
if xts == 'private'
crypto_ss.add(files('xts.c'))
endif
crypto_ss.add(when: 'CONFIG_SECRET_KEYRING', if_true: files('secret_keyring.c'))
crypto_ss.add(when: 'CONFIG_AF_ALG', if_true: files('afalg.c', 'cipher-afalg.c', 'hash-afalg.c'))

7
meson.build
View File

@ -826,7 +826,7 @@ endif
# Nettle has priority over gcrypt
gcrypt = not_found
nettle = not_found
xts = 'private'
xts = 'none'
if get_option('nettle').enabled() and get_option('gcrypt').enabled()
error('Only one of gcrypt & nettle can be enabled')
elif (not get_option('nettle').auto() or have_system) and not get_option('gcrypt').enabled()
@ -834,8 +834,8 @@ elif (not get_option('nettle').auto() or have_system) and not get_option('gcrypt
method: 'pkg-config',
required: get_option('nettle'),
kwargs: static_kwargs)
if nettle.found() and cc.has_header('nettle/xts.h', dependencies: nettle)
xts = 'nettle'
if nettle.found() and not cc.has_header('nettle/xts.h', dependencies: nettle)
xts = 'private'
endif
endif
if (not get_option('gcrypt').auto() or have_system) and not nettle.found()
@ -843,7 +843,6 @@ if (not get_option('gcrypt').auto() or have_system) and not nettle.found()
method: 'config-tool',
required: get_option('gcrypt'),
kwargs: static_kwargs)
xts = 'gcrypt'
# Debian has removed -lgpg-error from libgcrypt-config
# as it "spreads unnecessary dependencies" which in
# turn breaks static builds...