/*
* Copyright (C) 2000-2012 Free Software Foundation, Inc.
*
* Author: Nikos Mavrogiannopoulos
*
* This file is part of GnuTLS.
*
* The GnuTLS 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 program. If not, see
*
*/
/* This file contains the RSA key exchange part of the certificate
* authentication.
*/
#include "gnutls_int.h"
#include "gnutls_auth.h"
#include "gnutls_errors.h"
#include "gnutls_dh.h"
#include "gnutls_num.h"
#include "gnutls_datum.h"
#include
#include
#include
#include
#include "debug.h"
#include
#include
#include
#include
#include
#include
int _gnutls_gen_rsa_client_kx(gnutls_session_t, gnutls_buffer_st *);
static int proc_rsa_client_kx(gnutls_session_t, uint8_t *, size_t);
const mod_auth_st rsa_auth_struct = {
"RSA",
_gnutls_gen_cert_server_crt,
_gnutls_gen_cert_client_crt,
NULL, /* gen server kx */
_gnutls_gen_rsa_client_kx,
_gnutls_gen_cert_client_crt_vrfy, /* gen client cert vrfy */
_gnutls_gen_cert_server_cert_req, /* server cert request */
_gnutls_proc_crt,
_gnutls_proc_crt,
NULL, /* proc server kx */
proc_rsa_client_kx, /* proc client kx */
_gnutls_proc_cert_client_crt_vrfy, /* proc client cert vrfy */
_gnutls_proc_cert_cert_req /* proc server cert request */
};
/* This function reads the RSA parameters from peer's certificate;
*/
int
_gnutls_get_public_rsa_params(gnutls_session_t session,
gnutls_pk_params_st * params)
{
int ret;
cert_auth_info_t info;
gnutls_pcert_st peer_cert;
/* normal non export case */
info = _gnutls_get_auth_info(session, GNUTLS_CRD_CERTIFICATE);
if (info == NULL || info->ncerts == 0) {
gnutls_assert();
return GNUTLS_E_INTERNAL_ERROR;
}
ret =
_gnutls_get_auth_info_pcert(&peer_cert,
session->security_parameters.
cert_type, info);
if (ret < 0) {
gnutls_assert();
return ret;
}
gnutls_pk_params_init(params);
ret = _gnutls_pubkey_get_mpis(peer_cert.pubkey, params);
if (ret < 0) {
ret = gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
goto cleanup2;
}
gnutls_pcert_deinit(&peer_cert);
return 0;
cleanup2:
gnutls_pcert_deinit(&peer_cert);
return ret;
}
static int
proc_rsa_client_kx(gnutls_session_t session, uint8_t * data,
size_t _data_size)
{
gnutls_datum_t plaintext;
gnutls_datum_t ciphertext;
int ret, dsize;
int randomize_key = 0;
ssize_t data_size = _data_size;
if (get_num_version(session) == GNUTLS_SSL3) {
/* SSL 3.0
*/
ciphertext.data = data;
ciphertext.size = data_size;
} else {
/* TLS 1.0
*/
DECR_LEN(data_size, 2);
ciphertext.data = &data[2];
dsize = _gnutls_read_uint16(data);
if (dsize != data_size) {
gnutls_assert();
return GNUTLS_E_UNEXPECTED_PACKET_LENGTH;
}
ciphertext.size = dsize;
}
ret =
gnutls_privkey_decrypt_data(session->internals.selected_key, 0,
&ciphertext, &plaintext);
if (ret < 0 || plaintext.size != GNUTLS_MASTER_SIZE) {
/* In case decryption fails then don't inform
* the peer. Just use a random key. (in order to avoid
* attack against pkcs-1 formating).
*/
gnutls_assert();
_gnutls_audit_log(session,
"auth_rsa: Possible PKCS #1 format attack\n");
randomize_key = 1;
} else {
/* If the secret was properly formatted, then
* check the version number.
*/
if (_gnutls_get_adv_version_major(session) !=
plaintext.data[0]
|| (session->internals.priorities.allow_wrong_pms == 0
&& _gnutls_get_adv_version_minor(session) !=
plaintext.data[1])) {
/* No error is returned here, if the version number check
* fails. We proceed normally.
* That is to defend against the attack described in the paper
* "Attacking RSA-based sessions in SSL/TLS" by Vlastimil Klima,
* Ondej Pokorny and Tomas Rosa.
*/
gnutls_assert();
_gnutls_audit_log
(session,
"auth_rsa: Possible PKCS #1 version check format attack\n");
}
}
if (randomize_key != 0) {
session->key.key.size = GNUTLS_MASTER_SIZE;
session->key.key.data =
gnutls_malloc(session->key.key.size);
if (session->key.key.data == NULL) {
gnutls_assert();
return GNUTLS_E_MEMORY_ERROR;
}
/* we do not need strong random numbers here.
*/
ret = _gnutls_rnd(GNUTLS_RND_NONCE, session->key.key.data,
session->key.key.size);
if (ret < 0) {
gnutls_assert();
return ret;
}
} else {
session->key.key.data = plaintext.data;
session->key.key.size = plaintext.size;
}
/* This is here to avoid the version check attack
* discussed above.
*/
session->key.key.data[0] = _gnutls_get_adv_version_major(session);
session->key.key.data[1] = _gnutls_get_adv_version_minor(session);
return 0;
}
/* return RSA(random) using the peers public key
*/
int
_gnutls_gen_rsa_client_kx(gnutls_session_t session,
gnutls_buffer_st * data)
{
cert_auth_info_t auth = session->key.auth_info;
gnutls_datum_t sdata; /* data to send */
gnutls_pk_params_st params;
int ret;
if (auth == NULL) {
/* this shouldn't have happened. The proc_certificate
* function should have detected that.
*/
gnutls_assert();
return GNUTLS_E_INSUFFICIENT_CREDENTIALS;
}
session->key.key.size = GNUTLS_MASTER_SIZE;
session->key.key.data = gnutls_malloc(session->key.key.size);
if (session->key.key.data == NULL) {
gnutls_assert();
return GNUTLS_E_MEMORY_ERROR;
}
ret = _gnutls_rnd(GNUTLS_RND_RANDOM, session->key.key.data,
session->key.key.size);
if (ret < 0) {
gnutls_assert();
return ret;
}
if (session->internals.rsa_pms_version[0] == 0) {
session->key.key.data[0] =
_gnutls_get_adv_version_major(session);
session->key.key.data[1] =
_gnutls_get_adv_version_minor(session);
} else { /* use the version provided */
session->key.key.data[0] =
session->internals.rsa_pms_version[0];
session->key.key.data[1] =
session->internals.rsa_pms_version[1];
}
/* move RSA parameters to key (session).
*/
if ((ret = _gnutls_get_public_rsa_params(session, ¶ms)) < 0) {
gnutls_assert();
return ret;
}
ret =
_gnutls_pk_encrypt(GNUTLS_PK_RSA, &sdata, &session->key.key,
¶ms);
gnutls_pk_params_release(¶ms);
if (ret < 0)
return gnutls_assert_val(ret);
if (get_num_version(session) == GNUTLS_SSL3) {
/* SSL 3.0 */
_gnutls_buffer_replace_data(data, &sdata);
return data->length;
} else { /* TLS 1 */
ret =
_gnutls_buffer_append_data_prefix(data, 16, sdata.data,
sdata.size);
_gnutls_free_datum(&sdata);
return ret;
}
}