qemu/crypto/cipher-nettle.c
Daniel P. Berrange 3a661f1eab crypto: add sanity checking of plaintext/ciphertext length
When encrypting/decrypting data, the plaintext/ciphertext
buffers are required to be a multiple of the cipher block
size. If this is not done, nettle will abort and gcrypt
will report an error. To get consistent behaviour add
explicit checks upfront for the buffer sizes.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2015-10-22 19:03:08 +01:00

258 lines
6.9 KiB
C

/*
* QEMU Crypto cipher nettle algorithms
*
* Copyright (c) 2015 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 <nettle/nettle-types.h>
#include <nettle/aes.h>
#include <nettle/des.h>
#include <nettle/cbc.h>
#if CONFIG_NETTLE_VERSION_MAJOR < 3
typedef nettle_crypt_func nettle_cipher_func;
typedef void * cipher_ctx_t;
typedef unsigned cipher_length_t;
#else
typedef const void * cipher_ctx_t;
typedef size_t cipher_length_t;
#endif
static nettle_cipher_func aes_encrypt_wrapper;
static nettle_cipher_func aes_decrypt_wrapper;
static nettle_cipher_func des_encrypt_wrapper;
static nettle_cipher_func des_decrypt_wrapper;
static void aes_encrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length,
uint8_t *dst, const uint8_t *src)
{
aes_encrypt(ctx, length, dst, src);
}
static void aes_decrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length,
uint8_t *dst, const uint8_t *src)
{
aes_decrypt(ctx, length, dst, src);
}
static void des_encrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length,
uint8_t *dst, const uint8_t *src)
{
des_encrypt(ctx, length, dst, src);
}
static void des_decrypt_wrapper(cipher_ctx_t ctx, cipher_length_t length,
uint8_t *dst, const uint8_t *src)
{
des_decrypt(ctx, length, dst, src);
}
typedef struct QCryptoCipherNettle QCryptoCipherNettle;
struct QCryptoCipherNettle {
void *ctx_encrypt;
void *ctx_decrypt;
nettle_cipher_func *alg_encrypt;
nettle_cipher_func *alg_decrypt;
uint8_t *iv;
size_t blocksize;
};
bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg)
{
switch (alg) {
case QCRYPTO_CIPHER_ALG_DES_RFB:
case QCRYPTO_CIPHER_ALG_AES_128:
case QCRYPTO_CIPHER_ALG_AES_192:
case QCRYPTO_CIPHER_ALG_AES_256:
return true;
default:
return false;
}
}
QCryptoCipher *qcrypto_cipher_new(QCryptoCipherAlgorithm alg,
QCryptoCipherMode mode,
const uint8_t *key, size_t nkey,
Error **errp)
{
QCryptoCipher *cipher;
QCryptoCipherNettle *ctx;
uint8_t *rfbkey;
switch (mode) {
case QCRYPTO_CIPHER_MODE_ECB:
case QCRYPTO_CIPHER_MODE_CBC:
break;
default:
error_setg(errp, "Unsupported cipher mode %d", mode);
return NULL;
}
if (!qcrypto_cipher_validate_key_length(alg, nkey, errp)) {
return NULL;
}
cipher = g_new0(QCryptoCipher, 1);
cipher->alg = alg;
cipher->mode = mode;
ctx = g_new0(QCryptoCipherNettle, 1);
switch (alg) {
case QCRYPTO_CIPHER_ALG_DES_RFB:
ctx->ctx_encrypt = g_new0(struct des_ctx, 1);
ctx->ctx_decrypt = NULL; /* 1 ctx can do both */
rfbkey = qcrypto_cipher_munge_des_rfb_key(key, nkey);
des_set_key(ctx->ctx_encrypt, rfbkey);
g_free(rfbkey);
ctx->alg_encrypt = des_encrypt_wrapper;
ctx->alg_decrypt = des_decrypt_wrapper;
ctx->blocksize = DES_BLOCK_SIZE;
break;
case QCRYPTO_CIPHER_ALG_AES_128:
case QCRYPTO_CIPHER_ALG_AES_192:
case QCRYPTO_CIPHER_ALG_AES_256:
ctx->ctx_encrypt = g_new0(struct aes_ctx, 1);
ctx->ctx_decrypt = g_new0(struct aes_ctx, 1);
aes_set_encrypt_key(ctx->ctx_encrypt, nkey, key);
aes_set_decrypt_key(ctx->ctx_decrypt, nkey, key);
ctx->alg_encrypt = aes_encrypt_wrapper;
ctx->alg_decrypt = aes_decrypt_wrapper;
ctx->blocksize = AES_BLOCK_SIZE;
break;
default:
error_setg(errp, "Unsupported cipher algorithm %d", alg);
goto error;
}
ctx->iv = g_new0(uint8_t, ctx->blocksize);
cipher->opaque = ctx;
return cipher;
error:
g_free(cipher);
g_free(ctx);
return NULL;
}
void qcrypto_cipher_free(QCryptoCipher *cipher)
{
QCryptoCipherNettle *ctx;
if (!cipher) {
return;
}
ctx = cipher->opaque;
g_free(ctx->iv);
g_free(ctx->ctx_encrypt);
g_free(ctx->ctx_decrypt);
g_free(ctx);
g_free(cipher);
}
int qcrypto_cipher_encrypt(QCryptoCipher *cipher,
const void *in,
void *out,
size_t len,
Error **errp)
{
QCryptoCipherNettle *ctx = cipher->opaque;
if (len % ctx->blocksize) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctx->blocksize);
return -1;
}
switch (cipher->mode) {
case QCRYPTO_CIPHER_MODE_ECB:
ctx->alg_encrypt(ctx->ctx_encrypt, len, out, in);
break;
case QCRYPTO_CIPHER_MODE_CBC:
cbc_encrypt(ctx->ctx_encrypt, ctx->alg_encrypt,
ctx->blocksize, ctx->iv,
len, out, in);
break;
default:
error_setg(errp, "Unsupported cipher algorithm %d",
cipher->alg);
return -1;
}
return 0;
}
int qcrypto_cipher_decrypt(QCryptoCipher *cipher,
const void *in,
void *out,
size_t len,
Error **errp)
{
QCryptoCipherNettle *ctx = cipher->opaque;
if (len % ctx->blocksize) {
error_setg(errp, "Length %zu must be a multiple of block size %zu",
len, ctx->blocksize);
return -1;
}
switch (cipher->mode) {
case QCRYPTO_CIPHER_MODE_ECB:
ctx->alg_decrypt(ctx->ctx_decrypt ? ctx->ctx_decrypt : ctx->ctx_encrypt,
len, out, in);
break;
case QCRYPTO_CIPHER_MODE_CBC:
cbc_decrypt(ctx->ctx_decrypt ? ctx->ctx_decrypt : ctx->ctx_encrypt,
ctx->alg_decrypt, ctx->blocksize, ctx->iv,
len, out, in);
break;
default:
error_setg(errp, "Unsupported cipher algorithm %d",
cipher->alg);
return -1;
}
return 0;
}
int qcrypto_cipher_setiv(QCryptoCipher *cipher,
const uint8_t *iv, size_t niv,
Error **errp)
{
QCryptoCipherNettle *ctx = cipher->opaque;
if (niv != ctx->blocksize) {
error_setg(errp, "Expected IV size %zu not %zu",
ctx->blocksize, niv);
return -1;
}
memcpy(ctx->iv, iv, niv);
return 0;
}