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crypto: add gnutls cipher provider
Add an implementation of the QEMU cipher APIs to the gnutls crypto backend. XTS support is only available for gnutls version >= 3.6.8. Since ECB mode is not exposed by gnutls APIs, we can't use the private XTS code for compatibility. Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrangé
parent
cc4c7c7382
commit
3d2b61ffcd
2 changed files with 337 additions and 0 deletions
335
crypto/cipher-gnutls.c.inc
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335
crypto/cipher-gnutls.c.inc
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/*
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* QEMU Crypto cipher gnutls algorithms
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*
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* Copyright (c) 2021 Red Hat, Inc.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include "qemu/osdep.h"
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#include "cipherpriv.h"
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#include <gnutls/crypto.h>
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#if GNUTLS_VERSION_NUMBER >= 0x030608
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#define QEMU_GNUTLS_XTS
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#endif
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bool qcrypto_cipher_supports(QCryptoCipherAlgorithm alg,
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QCryptoCipherMode mode)
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{
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switch (mode) {
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case QCRYPTO_CIPHER_MODE_ECB:
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case QCRYPTO_CIPHER_MODE_CBC:
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switch (alg) {
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case QCRYPTO_CIPHER_ALG_AES_128:
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case QCRYPTO_CIPHER_ALG_AES_192:
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case QCRYPTO_CIPHER_ALG_AES_256:
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case QCRYPTO_CIPHER_ALG_DES:
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case QCRYPTO_CIPHER_ALG_3DES:
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return true;
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default:
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return false;
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}
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#ifdef QEMU_GNUTLS_XTS
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case QCRYPTO_CIPHER_MODE_XTS:
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switch (alg) {
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case QCRYPTO_CIPHER_ALG_AES_128:
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case QCRYPTO_CIPHER_ALG_AES_256:
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return true;
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default:
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return false;
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}
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#endif
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default:
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return false;
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}
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}
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typedef struct QCryptoCipherGnutls QCryptoCipherGnutls;
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struct QCryptoCipherGnutls {
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QCryptoCipher base;
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gnutls_cipher_hd_t handle; /* XTS & CBC mode */
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gnutls_cipher_algorithm_t galg; /* ECB mode */
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guint8 *key; /* ECB mode */
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size_t nkey; /* ECB mode */
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size_t blocksize;
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};
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static void
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qcrypto_gnutls_cipher_free(QCryptoCipher *cipher)
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{
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QCryptoCipherGnutls *ctx = container_of(cipher, QCryptoCipherGnutls, base);
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g_free(ctx->key);
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if (ctx->handle) {
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gnutls_cipher_deinit(ctx->handle);
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}
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g_free(ctx);
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}
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static int
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qcrypto_gnutls_cipher_encrypt(QCryptoCipher *cipher,
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const void *in,
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void *out,
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size_t len,
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Error **errp)
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{
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QCryptoCipherGnutls *ctx = container_of(cipher, QCryptoCipherGnutls, base);
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int err;
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if (len % ctx->blocksize) {
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error_setg(errp, "Length %zu must be a multiple of block size %zu",
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len, ctx->blocksize);
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return -1;
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}
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if (ctx->handle) { /* CBC / XTS mode */
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err = gnutls_cipher_encrypt2(ctx->handle,
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in, len,
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out, len);
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if (err != 0) {
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error_setg(errp, "Cannot encrypt data: %s",
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gnutls_strerror(err));
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return -1;
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}
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} else { /* ECB mode very inefficiently faked with CBC */
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g_autofree unsigned char *iv = g_new0(unsigned char, ctx->blocksize);
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while (len) {
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gnutls_cipher_hd_t handle;
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gnutls_datum_t gkey = { (unsigned char *)ctx->key, ctx->nkey };
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int err = gnutls_cipher_init(&handle, ctx->galg, &gkey, NULL);
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if (err != 0) {
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error_setg(errp, "Cannot initialize cipher: %s",
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gnutls_strerror(err));
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return -1;
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}
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gnutls_cipher_set_iv(handle, iv, ctx->blocksize);
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err = gnutls_cipher_encrypt2(handle,
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in, ctx->blocksize,
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out, ctx->blocksize);
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if (err != 0) {
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gnutls_cipher_deinit(handle);
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error_setg(errp, "Cannot encrypt data: %s",
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gnutls_strerror(err));
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return -1;
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}
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gnutls_cipher_deinit(handle);
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len -= ctx->blocksize;
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in += ctx->blocksize;
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out += ctx->blocksize;
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}
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}
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return 0;
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}
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static int
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qcrypto_gnutls_cipher_decrypt(QCryptoCipher *cipher,
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const void *in,
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void *out,
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size_t len,
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Error **errp)
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{
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QCryptoCipherGnutls *ctx = container_of(cipher, QCryptoCipherGnutls, base);
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int err;
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if (len % ctx->blocksize) {
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error_setg(errp, "Length %zu must be a multiple of block size %zu",
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len, ctx->blocksize);
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return -1;
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}
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if (ctx->handle) { /* CBC / XTS mode */
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err = gnutls_cipher_decrypt2(ctx->handle,
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in, len,
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out, len);
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if (err != 0) {
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error_setg(errp, "Cannot decrypt data: %s",
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gnutls_strerror(err));
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return -1;
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}
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} else { /* ECB mode very inefficiently faked with CBC */
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g_autofree unsigned char *iv = g_new0(unsigned char, ctx->blocksize);
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while (len) {
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gnutls_cipher_hd_t handle;
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gnutls_datum_t gkey = { (unsigned char *)ctx->key, ctx->nkey };
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int err = gnutls_cipher_init(&handle, ctx->galg, &gkey, NULL);
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if (err != 0) {
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error_setg(errp, "Cannot initialize cipher: %s",
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gnutls_strerror(err));
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return -1;
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}
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gnutls_cipher_set_iv(handle, iv, ctx->blocksize);
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err = gnutls_cipher_decrypt2(handle,
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in, ctx->blocksize,
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out, ctx->blocksize);
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if (err != 0) {
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gnutls_cipher_deinit(handle);
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error_setg(errp, "Cannot encrypt data: %s",
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gnutls_strerror(err));
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return -1;
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}
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gnutls_cipher_deinit(handle);
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len -= ctx->blocksize;
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in += ctx->blocksize;
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out += ctx->blocksize;
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}
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}
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return 0;
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}
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static int
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qcrypto_gnutls_cipher_setiv(QCryptoCipher *cipher,
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const uint8_t *iv, size_t niv,
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Error **errp)
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{
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QCryptoCipherGnutls *ctx = container_of(cipher, QCryptoCipherGnutls, base);
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if (niv != ctx->blocksize) {
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error_setg(errp, "Expected IV size %zu not %zu",
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ctx->blocksize, niv);
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return -1;
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}
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gnutls_cipher_set_iv(ctx->handle, (unsigned char *)iv, niv);
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return 0;
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}
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static struct QCryptoCipherDriver gnutls_driver = {
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.cipher_encrypt = qcrypto_gnutls_cipher_encrypt,
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.cipher_decrypt = qcrypto_gnutls_cipher_decrypt,
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.cipher_setiv = qcrypto_gnutls_cipher_setiv,
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.cipher_free = qcrypto_gnutls_cipher_free,
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};
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static QCryptoCipher *qcrypto_cipher_ctx_new(QCryptoCipherAlgorithm alg,
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QCryptoCipherMode mode,
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const uint8_t *key,
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size_t nkey,
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Error **errp)
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{
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QCryptoCipherGnutls *ctx;
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gnutls_datum_t gkey = { (unsigned char *)key, nkey };
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gnutls_cipher_algorithm_t galg = GNUTLS_CIPHER_UNKNOWN;
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int err;
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switch (mode) {
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#ifdef QEMU_GNUTLS_XTS
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case QCRYPTO_CIPHER_MODE_XTS:
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switch (alg) {
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case QCRYPTO_CIPHER_ALG_AES_128:
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galg = GNUTLS_CIPHER_AES_128_XTS;
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break;
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case QCRYPTO_CIPHER_ALG_AES_256:
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galg = GNUTLS_CIPHER_AES_256_XTS;
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break;
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default:
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break;
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}
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break;
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#endif
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case QCRYPTO_CIPHER_MODE_ECB:
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case QCRYPTO_CIPHER_MODE_CBC:
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switch (alg) {
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case QCRYPTO_CIPHER_ALG_AES_128:
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galg = GNUTLS_CIPHER_AES_128_CBC;
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break;
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case QCRYPTO_CIPHER_ALG_AES_192:
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galg = GNUTLS_CIPHER_AES_192_CBC;
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break;
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case QCRYPTO_CIPHER_ALG_AES_256:
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galg = GNUTLS_CIPHER_AES_256_CBC;
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break;
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case QCRYPTO_CIPHER_ALG_DES:
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galg = GNUTLS_CIPHER_DES_CBC;
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break;
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case QCRYPTO_CIPHER_ALG_3DES:
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galg = GNUTLS_CIPHER_3DES_CBC;
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break;
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default:
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break;
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}
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break;
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default:
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break;
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}
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if (galg == GNUTLS_CIPHER_UNKNOWN) {
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error_setg(errp, "Unsupported cipher algorithm %s with %s mode",
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QCryptoCipherAlgorithm_str(alg),
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QCryptoCipherMode_str(mode));
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return NULL;
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}
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if (!qcrypto_cipher_validate_key_length(alg, mode, nkey, errp)) {
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return NULL;
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}
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ctx = g_new0(QCryptoCipherGnutls, 1);
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ctx->base.driver = &gnutls_driver;
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if (mode == QCRYPTO_CIPHER_MODE_ECB) {
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ctx->key = g_new0(guint8, nkey);
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memcpy(ctx->key, key, nkey);
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ctx->nkey = nkey;
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ctx->galg = galg;
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} else {
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err = gnutls_cipher_init(&ctx->handle, galg, &gkey, NULL);
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if (err != 0) {
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error_setg(errp, "Cannot initialize cipher: %s",
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gnutls_strerror(err));
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goto error;
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}
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}
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if (alg == QCRYPTO_CIPHER_ALG_DES ||
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alg == QCRYPTO_CIPHER_ALG_3DES)
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ctx->blocksize = 8;
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else
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ctx->blocksize = 16;
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/*
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* Our API contract for requires iv to be optional
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* but nettle gets unhappy when called by gnutls
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* in this case, so we just force set a default
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* all-zeros IV, to match behaviour of other backends.
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*/
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if (mode != QCRYPTO_CIPHER_MODE_ECB) {
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g_autofree unsigned char *iv = g_new0(unsigned char, ctx->blocksize);
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gnutls_cipher_set_iv(ctx->handle, iv, ctx->blocksize);
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}
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return &ctx->base;
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error:
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qcrypto_gnutls_cipher_free(&ctx->base);
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return NULL;
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}
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@ -136,6 +136,8 @@ qcrypto_cipher_validate_key_length(QCryptoCipherAlgorithm alg,
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#include "cipher-gcrypt.c.inc"
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#elif defined CONFIG_NETTLE
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#include "cipher-nettle.c.inc"
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#elif defined CONFIG_GNUTLS_CRYPTO
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#include "cipher-gnutls.c.inc"
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#else
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#include "cipher-builtin.c.inc"
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#endif
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