Add test to ensure DH exchange behaves correctly

This test ensures that public keys are properly tested for validity
before a DH exchange is computed.

Signed-off-by: Simo Sorce <simo@redhat.com>

2 files changed, 156 insertions, 1 deletions

diff --git a/tests/Makefile.am b/tests/Makefile.am
index 05c0a61b79..5e3cd3d934 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -209,7 +209,7 @@ ctests += mini-record-2 simple gnutls_hmac_fast set_pkcs12_cred cert certuniquei
 	 tls13-server-kx-neg gnutls_ext_raw_parse_dtls key-export-pkcs8 \
 	 null_retrieve_function tls-record-size-limit tls-crt_type-neg \
 	 resume-with-stek-expiration resume-with-previous-stek rawpk-api \
-	 tls-record-size-limit-asym
+	 tls-record-size-limit-asym dh-compute
 
 if HAVE_SECCOMP_TESTS
 ctests += dtls-with-seccomp tls-with-seccomp dtls-client-with-seccomp tls-client-with-seccomp
diff --git a/tests/dh-compute.c b/tests/dh-compute.c
new file mode 100644
index 0000000000..173729312e
--- /dev/null
+++ b/tests/dh-compute.c
@@ -0,0 +1,155 @@
+/*
+ * Copyright (C) 2019 Red Hat, Inc.
+ *
+ * Author: Simo Sorce
+ *
+ * This file is part of GnuTLS.
+ *
+ * GnuTLS is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuTLS 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GnuTLS; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+/* This program tests functionality of DH exchanges */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <gnutls/gnutls.h>
+#include <stdbool.h>
+#include <string.h>
+#include <stdlib.h>
+#include "utils.h"
+
+#ifdef ENABLE_FIPS140
+int _gnutls_dh_generate_key(gnutls_dh_params_t dh_params,
+			    gnutls_datum_t *priv_key, gnutls_datum_t *pub_key);
+
+int _gnutls_dh_compute_key(gnutls_dh_params_t dh_params,
+			   const gnutls_datum_t *priv_key,
+			   const gnutls_datum_t *pub_key,
+			   const gnutls_datum_t *peer_key, gnutls_datum_t *Z);
+
+static void params(gnutls_dh_params_t *dh_params, unsigned int key_bits,
+		   const gnutls_datum_t *p, const gnutls_datum_t *g)
+{
+	int ret;
+
+	ret = gnutls_dh_params_init(dh_params);
+	if (ret != 0)
+		fail("error\n");
+
+	ret = gnutls_dh_params_import_raw2(*dh_params, p, g, key_bits);
+	if (ret != 0)
+		fail("error\n");
+}
+
+static void genkey(gnutls_dh_params_t *dh_params,
+		   gnutls_datum_t *priv_key, gnutls_datum_t *pub_key)
+{
+	int ret;
+
+	ret = _gnutls_dh_generate_key(*dh_params, priv_key, pub_key);
+	if (ret != 0)
+		fail("error\n");
+}
+
+static void compute_key(gnutls_dh_params_t *dh_params,
+			gnutls_datum_t *priv_key, gnutls_datum_t *pub_key,
+			const gnutls_datum_t *peer_key, int expect_error,
+			gnutls_datum_t *result, bool expect_success)
+{
+	gnutls_datum_t Z;
+	bool success;
+	int ret;
+
+	ret = _gnutls_dh_compute_key(*dh_params, priv_key, pub_key,
+				     peer_key, &Z);
+	if (expect_error != ret)
+		fail("error (%d)\n", ret);
+
+	if (result) {
+		success = (Z.size != result->size &&
+			   memcmp(Z.data, result->data, Z.size));
+		if (success != expect_success)
+			fail("error\n");
+	}
+	gnutls_free(Z.data);
+}
+
+struct dh_test_data {
+	const unsigned int key_size;
+	const gnutls_datum_t prime;
+	const gnutls_datum_t generator;
+	const gnutls_datum_t peer_key;
+	int expected_error;
+};
+
+void doit(void)
+{
+	struct dh_test_data test_data[] = {
+		{
+                        /* y == 0 */
+			gnutls_ffdhe_2048_key_bits,
+			gnutls_ffdhe_2048_group_prime,
+			gnutls_ffdhe_2048_group_generator,
+			{ (void *)"\x00", 1 },
+			GNUTLS_E_MPI_SCAN_FAILED
+		},
+		{
+                        /* y < 2 */
+			gnutls_ffdhe_2048_key_bits,
+			gnutls_ffdhe_2048_group_prime,
+			gnutls_ffdhe_2048_group_generator,
+			{ (void *)"\x01", 1 },
+			GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER
+		},
+		{
+                        /* y > p - 2 */
+			gnutls_ffdhe_2048_key_bits,
+			gnutls_ffdhe_2048_group_prime,
+			gnutls_ffdhe_2048_group_generator,
+			gnutls_ffdhe_2048_group_prime,
+			GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER
+		},
+		{ 0 }
+	};
+
+	for (int i = 0; test_data[i].key_size != 0; i++) {
+		gnutls_datum_t priv_key, pub_key;
+		gnutls_dh_params_t dh_params;
+
+		params(&dh_params, test_data[i].key_size,
+		       &test_data[i].prime, &test_data[i].generator);
+
+		genkey(&dh_params, &priv_key, &pub_key);
+
+		compute_key(&dh_params, &priv_key, &pub_key,
+			    &test_data[i].peer_key,
+			    test_data[i].expected_error,
+			    NULL, 0);
+
+		gnutls_dh_params_deinit(dh_params);
+		gnutls_free(priv_key.data);
+		gnutls_free(pub_key.data);
+	}
+
+	success("all ok\n");
+}
+#else
+void doit(void)
+{
+	return;
+}
+#endif