1 files changed, 379 insertions, 0 deletions

diff --git a/lib/auth/dh_common.c b/lib/auth/dh_common.c
new file mode 100644
index 0000000..fcd696d
--- /dev/null
+++ b/lib/auth/dh_common.c
@@ -0,0 +1,379 @@
+/*
+ * Copyright (C) 2002-2012 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 <https://www.gnu.org/licenses/>
+ *
+ */
+
+/* This file contains common stuff in Ephemeral Diffie-Hellman (DHE)
+ * and Anonymous DH key exchange(DHA). These are used in the handshake
+ * procedure of the certificate and anonymous authentication.
+ */
+
+#include "gnutls_int.h"
+#include "auth.h"
+#include "errors.h"
+#include "dh.h"
+#include "num.h"
+#include "tls-sig.h"
+#include <datum.h>
+#include <x509.h>
+#include <state.h>
+#include <pk.h>
+#include <auth/dh_common.h>
+#include <algorithms.h>
+#include <auth/psk.h>
+
+#if defined(ENABLE_DHE) || defined(ENABLE_ANON)
+
+/* Frees the dh_info_st structure.
+ */
+void _gnutls_free_dh_info(dh_info_st * dh)
+{
+	dh->secret_bits = 0;
+	_gnutls_free_datum(&dh->prime);
+	_gnutls_free_datum(&dh->generator);
+	_gnutls_free_datum(&dh->public_key);
+}
+
+int
+_gnutls_proc_dh_common_client_kx(gnutls_session_t session,
+				 uint8_t * data, size_t _data_size,
+				 gnutls_datum_t * psk_key)
+{
+	uint16_t n_Y;
+	size_t _n_Y;
+	int ret;
+	ssize_t data_size = _data_size;
+	gnutls_datum_t tmp_dh_key = {NULL, 0};
+	gnutls_pk_params_st peer_pub;
+	
+	gnutls_pk_params_init(&peer_pub);
+
+	DECR_LEN(data_size, 2);
+	n_Y = _gnutls_read_uint16(&data[0]);
+	_n_Y = n_Y;
+
+	DECR_LEN(data_size, n_Y);
+
+	if (data_size != 0)
+		return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);
+
+	if (_gnutls_mpi_init_scan_nz(&session->key.proto.tls12.dh.client_Y, &data[2], _n_Y)) {
+		gnutls_assert();
+		return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER; /* most likely zero or illegal size */
+	}
+
+	_gnutls_dh_set_peer_public(session, session->key.proto.tls12.dh.client_Y);
+
+	peer_pub.params[DH_Y] = session->key.proto.tls12.dh.client_Y;
+
+	/* calculate the key after calculating the message */
+	ret = _gnutls_pk_derive(GNUTLS_PK_DH, &tmp_dh_key, &session->key.proto.tls12.dh.params, &peer_pub);
+	if (ret < 0) {
+		gnutls_assert();
+		goto error;
+	}
+
+	if (psk_key == NULL) {
+		session->key.key.data = tmp_dh_key.data;
+		session->key.key.size = tmp_dh_key.size;
+	} else {		/* In DHE_PSK the key is set differently */
+		ret =
+		    _gnutls_set_psk_session_key(session, psk_key,
+						&tmp_dh_key);
+		_gnutls_free_temp_key_datum(&tmp_dh_key);
+	}
+	
+	if (ret < 0) {
+		gnutls_assert();
+		goto error;
+	}
+
+	ret = 0;
+ error:
+	_gnutls_mpi_release(&session->key.proto.tls12.dh.client_Y);
+	gnutls_pk_params_clear(&session->key.proto.tls12.dh.params);
+
+	return ret;
+}
+
+int _gnutls_gen_dh_common_client_kx(gnutls_session_t session,
+				    gnutls_buffer_st * data)
+{
+	return _gnutls_gen_dh_common_client_kx_int(session, data, NULL);
+}
+
+int
+_gnutls_gen_dh_common_client_kx_int(gnutls_session_t session,
+				    gnutls_buffer_st * data,
+				    gnutls_datum_t * pskkey)
+{
+	int ret;
+	gnutls_pk_params_st peer_pub;
+	gnutls_datum_t tmp_dh_key = {NULL, 0};
+	unsigned init_pos = data->length;
+	
+	gnutls_pk_params_init(&peer_pub);
+
+	ret =
+	    _gnutls_pk_generate_keys(GNUTLS_PK_DH, 0,
+				     &session->key.proto.tls12.dh.params, 1);
+	if (ret < 0)
+		return gnutls_assert_val(ret);
+
+	_gnutls_dh_set_secret_bits(session, _gnutls_mpi_get_nbits(session->key.proto.tls12.dh.params.params[DH_X]));
+
+	ret = _gnutls_buffer_append_mpi(data, 16, session->key.proto.tls12.dh.params.params[DH_Y], 0);
+	if (ret < 0) {
+		gnutls_assert();
+		goto error;
+	}
+	
+	peer_pub.params[DH_Y] = session->key.proto.tls12.dh.client_Y;
+
+	/* calculate the key after calculating the message */
+	ret = _gnutls_pk_derive(GNUTLS_PK_DH, &tmp_dh_key, &session->key.proto.tls12.dh.params, &peer_pub);
+	if (ret < 0) {
+		gnutls_assert();
+		goto error;
+	}
+
+	if (session->security_parameters.cs->kx_algorithm != GNUTLS_KX_DHE_PSK) {
+		session->key.key.data = tmp_dh_key.data;
+		session->key.key.size = tmp_dh_key.size;
+	} else {		/* In DHE_PSK the key is set differently */
+		ret =
+		    _gnutls_set_psk_session_key(session, pskkey,
+						&tmp_dh_key);
+		_gnutls_free_temp_key_datum(&tmp_dh_key);
+	}
+
+	if (ret < 0) {
+		gnutls_assert();
+		goto error;
+	}
+
+	ret = data->length - init_pos;
+
+ error:
+	gnutls_pk_params_clear(&session->key.proto.tls12.dh.params);
+	return ret;
+}
+
+/* Returns the bytes parsed */
+int
+_gnutls_proc_dh_common_server_kx(gnutls_session_t session,
+				 uint8_t * data, size_t _data_size)
+{
+	uint16_t n_Y, n_g, n_p;
+	size_t _n_Y, _n_g, _n_p, _n_q;
+	uint8_t *data_p;
+	uint8_t *data_g;
+	uint8_t *data_Y;
+	uint8_t *data_q = NULL;
+	int i, bits, ret, p_bits;
+	unsigned j;
+	ssize_t data_size = _data_size;
+
+	/* just in case we are resuming a session */
+	gnutls_pk_params_release(&session->key.proto.tls12.dh.params);
+
+	gnutls_pk_params_init(&session->key.proto.tls12.dh.params);
+
+	i = 0;
+
+	DECR_LEN(data_size, 2);
+	n_p = _gnutls_read_uint16(&data[i]);
+	i += 2;
+
+	DECR_LEN(data_size, n_p);
+	data_p = &data[i];
+	i += n_p;
+
+	DECR_LEN(data_size, 2);
+	n_g = _gnutls_read_uint16(&data[i]);
+	i += 2;
+
+	DECR_LEN(data_size, n_g);
+	data_g = &data[i];
+	i += n_g;
+
+	DECR_LEN(data_size, 2);
+	n_Y = _gnutls_read_uint16(&data[i]);
+	i += 2;
+
+	DECR_LEN(data_size, n_Y);
+	data_Y = &data[i];
+
+	_n_Y = n_Y;
+	_n_g = n_g;
+	_n_p = n_p;
+
+	if (_gnutls_mpi_init_scan_nz(&session->key.proto.tls12.dh.client_Y, data_Y, _n_Y) != 0) {
+		gnutls_assert();
+		return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
+	}
+
+	/* if we are doing RFC7919 */
+	if (session->internals.priorities->groups.have_ffdhe != 0) {
+		/* verify whether the received parameters match the advertised, otherwise
+		 * log that. */
+		for (j=0;j<session->internals.priorities->groups.size;j++) {
+			if (session->internals.priorities->groups.entry[j]->generator &&
+			    session->internals.priorities->groups.entry[j]->generator->size == n_g &&
+			    session->internals.priorities->groups.entry[j]->prime->size == n_p &&
+			    memcmp(session->internals.priorities->groups.entry[j]->generator->data,
+				   data_g, n_g) == 0 &&
+			    memcmp(session->internals.priorities->groups.entry[j]->prime->data,
+				   data_p, n_p) == 0) {
+
+				session->internals.hsk_flags |= HSK_USED_FFDHE;
+				_gnutls_session_group_set(session, session->internals.priorities->groups.entry[j]);
+				session->key.proto.tls12.dh.params.qbits = *session->internals.priorities->groups.entry[j]->q_bits;
+				data_q = session->internals.priorities->groups.entry[j]->q->data;
+				_n_q = session->internals.priorities->groups.entry[j]->q->size;
+				break;
+			}
+		}
+
+		if (!(session->internals.hsk_flags & HSK_USED_FFDHE)) {
+			_gnutls_audit_log(session, "FFDHE groups advertised, but server didn't support it; falling back to server's choice\n");
+		}
+	}
+
+#ifdef ENABLE_FIPS140
+	if (gnutls_fips140_mode_enabled() &&
+	    !_gnutls_dh_prime_match_fips_approved(data_p, n_p, data_g, n_g, NULL, NULL)) {
+		gnutls_assert();
+		return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
+	}
+#endif
+
+	if (_gnutls_mpi_init_scan_nz(&session->key.proto.tls12.dh.params.params[DH_G], data_g, _n_g) != 0) {
+		gnutls_assert();
+		return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
+	}
+
+	if (_gnutls_mpi_init_scan_nz(&session->key.proto.tls12.dh.params.params[DH_P], data_p, _n_p) != 0) {
+		gnutls_assert();
+		/* we release now because session->key.proto.tls12.dh.params.params_nr is not yet set */
+		_gnutls_mpi_release(&session->key.proto.tls12.dh.params.params[DH_G]);
+		return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
+	}
+	if (data_q && _gnutls_mpi_init_scan_nz(
+			    &session->key.proto.tls12.dh.params.params[DH_Q],
+			    data_q, _n_q) != 0) {
+		/* we release now because params_nr is not yet set */
+		_gnutls_mpi_release(
+			&session->key.proto.tls12.dh.params.params[DH_P]);
+		_gnutls_mpi_release(
+			&session->key.proto.tls12.dh.params.params[DH_G]);
+		return GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER;
+	}
+
+	/* include, possibly empty, q */
+	session->key.proto.tls12.dh.params.params_nr = 3;
+	session->key.proto.tls12.dh.params.algo = GNUTLS_PK_DH;
+
+	if (!(session->internals.hsk_flags & HSK_USED_FFDHE)) {
+		bits = _gnutls_dh_get_min_prime_bits(session);
+		if (bits < 0) {
+			gnutls_assert();
+			return bits;
+		}
+
+		p_bits = _gnutls_mpi_get_nbits(session->key.proto.tls12.dh.params.params[DH_P]);
+		if (p_bits < bits) {
+			/* the prime used by the peer is not acceptable
+			 */
+			gnutls_assert();
+			_gnutls_debug_log
+			    ("Received a prime of %u bits, limit is %u\n",
+			     (unsigned) _gnutls_mpi_get_nbits(session->key.proto.tls12.dh.params.params[DH_P]),
+			     (unsigned) bits);
+			return GNUTLS_E_DH_PRIME_UNACCEPTABLE;
+		}
+
+		if (p_bits >= DEFAULT_MAX_VERIFY_BITS) {
+			gnutls_assert();
+			_gnutls_debug_log
+			    ("Received a prime of %u bits, limit is %u\n",
+			     (unsigned) p_bits,
+			     (unsigned) DEFAULT_MAX_VERIFY_BITS);
+			return GNUTLS_E_DH_PRIME_UNACCEPTABLE;
+		}
+	}
+
+	_gnutls_dh_save_group(session, session->key.proto.tls12.dh.params.params[DH_G],
+			     session->key.proto.tls12.dh.params.params[DH_P]);
+	_gnutls_dh_set_peer_public(session, session->key.proto.tls12.dh.client_Y);
+
+	ret = n_Y + n_p + n_g + 6;
+
+	return ret;
+}
+
+int
+_gnutls_dh_common_print_server_kx(gnutls_session_t session,
+				  gnutls_buffer_st * data)
+{
+	int ret;
+	unsigned q_bits = session->key.proto.tls12.dh.params.qbits;
+	unsigned init_pos = data->length;
+
+	if (q_bits < 192 && q_bits != 0) {
+		gnutls_assert();
+		_gnutls_debug_log("too small q_bits value for DH: %u\n", q_bits);
+		q_bits = 0; /* auto-detect */
+	}
+
+	/* Y=g^x mod p */
+	ret =
+	    _gnutls_pk_generate_keys(GNUTLS_PK_DH, q_bits,
+				     &session->key.proto.tls12.dh.params, 1);
+	if (ret < 0)
+		return gnutls_assert_val(ret);
+
+	_gnutls_dh_set_secret_bits(session, _gnutls_mpi_get_nbits(session->key.proto.tls12.dh.params.params[DH_X]));
+
+	ret = _gnutls_buffer_append_mpi(data, 16, session->key.proto.tls12.dh.params.params[DH_P], 0);
+	if (ret < 0) {
+		gnutls_assert();
+		goto cleanup;
+	}
+
+	ret = _gnutls_buffer_append_mpi(data, 16, session->key.proto.tls12.dh.params.params[DH_G], 0);
+	if (ret < 0) {
+		gnutls_assert();
+		goto cleanup;
+	}
+
+	ret = _gnutls_buffer_append_mpi(data, 16, session->key.proto.tls12.dh.params.params[DH_Y], 0);
+	if (ret < 0) {
+		gnutls_assert();
+		goto cleanup;
+	}
+
+	ret = data->length - init_pos;
+
+cleanup:
+	return ret;
+}
+
+#endif