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/*
* Copyright (C) 2017-2019 Red Hat, 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 <https://www.gnu.org/licenses/>
*
*/
#include "gnutls_int.h"
#include "errors.h"
#include <auth/cert.h>
#include <algorithms.h>
#include <ext/signature.h>
#include <abstract_int.h>
#include "tls13-sig.h"
#include "tls-sig.h"
#include "hash_int.h"
#undef PREFIX_SIZE
#define PREFIX_SIZE 64
#if PREFIX_SIZE < MAX_HASH_SIZE
/* we assume later that prefix is sufficient to store hash output */
# error Need to modify code
#endif
int
_gnutls13_handshake_verify_data(gnutls_session_t session,
unsigned verify_flags,
gnutls_pcert_st *cert,
const gnutls_datum_t *context,
const gnutls_datum_t *signature,
const gnutls_sign_entry_st *se)
{
int ret;
const version_entry_st *ver = get_version(session);
gnutls_buffer_st buf;
uint8_t prefix[PREFIX_SIZE];
unsigned key_usage = 0;
gnutls_datum_t p;
_gnutls_handshake_log
("HSK[%p]: verifying TLS 1.3 handshake data using %s\n", session,
se->name);
ret =
_gnutls_pubkey_compatible_with_sig(session,
cert->pubkey, ver,
se->id);
if (ret < 0)
return gnutls_assert_val(ret);
if (unlikely(sign_supports_cert_pk_algorithm(se, cert->pubkey->params.algo) == 0)) {
_gnutls_handshake_log("HSK[%p]: certificate of %s cannot be combined with %s sig\n",
session, gnutls_pk_get_name(cert->pubkey->params.algo), se->name);
return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);
}
ret =
_gnutls_session_sign_algo_enabled(session, se->id);
if (ret < 0)
return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);
if ((se->flags & GNUTLS_SIGN_FLAG_TLS13_OK) == 0) /* explicitly prohibited */
return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);
gnutls_pubkey_get_key_usage(cert->pubkey, &key_usage);
ret = _gnutls_check_key_usage_for_sig(session, key_usage, 0);
if (ret < 0)
return gnutls_assert_val(ret);
_gnutls_buffer_init(&buf);
memset(prefix, 0x20, sizeof(prefix));
ret = _gnutls_buffer_append_data(&buf, prefix, sizeof(prefix));
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
ret = _gnutls_buffer_append_data(&buf, context->data, context->size);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
ret = _gnutls_buffer_append_data(&buf, "\x00", 1);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
ret = gnutls_hash_fast(MAC_TO_DIG(session->security_parameters.prf->id),
session->internals.handshake_hash_buffer.data,
session->internals.handshake_hash_buffer_prev_len,
prefix);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
ret = _gnutls_buffer_append_data(&buf, prefix, session->security_parameters.prf->output_size);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
p.data = buf.data;
p.size = buf.length;
/* Here we intentionally enable flag GNUTLS_VERIFY_ALLOW_BROKEN
* because we have checked whether the currently used signature
* algorithm is allowed in the session. */
ret = gnutls_pubkey_verify_data2(cert->pubkey, se->id,
verify_flags|GNUTLS_VERIFY_ALLOW_BROKEN,
&p, signature);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
ret = 0;
cleanup:
_gnutls_buffer_clear(&buf);
return ret;
}
int
_gnutls13_handshake_sign_data(gnutls_session_t session,
gnutls_pcert_st * cert, gnutls_privkey_t pkey,
const gnutls_datum_t *context,
gnutls_datum_t * signature,
const gnutls_sign_entry_st *se)
{
gnutls_datum_t p;
int ret;
gnutls_buffer_st buf;
uint8_t tmp[MAX_HASH_SIZE];
if (unlikely(se == NULL || (se->flags & GNUTLS_SIGN_FLAG_TLS13_OK) == 0))
return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);
if (unlikely(sign_supports_priv_pk_algorithm(se, pkey->pk_algorithm) == 0))
return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);
/* when we reach here we know we have a signing certificate */
_gnutls_handshake_log
("HSK[%p]: signing TLS 1.3 handshake data: using %s and PRF: %s\n", session, se->name,
session->security_parameters.prf->name);
_gnutls_buffer_init(&buf);
ret = _gnutls_buffer_resize(&buf, PREFIX_SIZE);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
memset(buf.data, 0x20, PREFIX_SIZE);
buf.length += PREFIX_SIZE;
ret = _gnutls_buffer_append_data(&buf, context->data, context->size);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
ret = _gnutls_buffer_append_data(&buf, "\x00", 1);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
ret = gnutls_hash_fast(MAC_TO_DIG(session->security_parameters.prf->id),
session->internals.handshake_hash_buffer.data,
session->internals.handshake_hash_buffer.length,
tmp);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
ret = _gnutls_buffer_append_data(&buf, tmp, session->security_parameters.prf->output_size);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
p.data = buf.data;
p.size = buf.length;
ret = gnutls_privkey_sign_data2(pkey, se->id, 0, &p, signature);
if (ret < 0) {
gnutls_assert();
goto cleanup;
}
ret = 0;
cleanup:
_gnutls_buffer_clear(&buf);
return ret;
}
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