Add server side support for supported_versions extension (cd998837) · Commits · CYBER - Cyber Security / TS 103 523 MSP / TLMSP / TLMSP OpenSSL

ssl/ssl_locl.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -2077,6 +2077,9 @@ __owur int dtls1_process_heartbeat(SSL s, unsigned char p,
		size_t length);
		# endif

		__owur RAW_EXTENSION tls_get_extension_by_type(RAW_EXTENSION exts,
		size_t numexts,
		unsigned int type);
		__owur int tls_get_ticket_from_client(SSL s, CLIENTHELLO_MSG hello,
		SSL_SESSION **ret);
		__owur int tls_check_client_ems_support(SSL s, const CLIENTHELLO_MSG hello);

ssl/statem/statem_clnt.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -779,8 +779,13 @@ int tls_construct_client_hello(SSL s, WPACKET pkt)
		* TLS 1.0 and renegotiating with TLS 1.2. We do this by using
		* client_version in client hello and not resetting it to
		* the negotiated version.
		*
		* For TLS 1.3 we always set the ClientHello version to 1.2 and rely on the
		* supported_versions extension for the reall supported versions.
		*/
		if (!WPACKET_put_bytes_u16(pkt, s->client_version)
		if (!WPACKET_put_bytes_u16(pkt,
		(!SSL_IS_DTLS(s) && s->client_version >= TLS1_3_VERSION)
		? TLS1_2_VERSION : s->client_version)
		\|\| !WPACKET_memcpy(pkt, s->s3->client_random, SSL3_RANDOM_SIZE)) {
		SSLerr(SSL_F_TLS_CONSTRUCT_CLIENT_HELLO, ERR_R_INTERNAL_ERROR);
		return 0;

ssl/statem/statem_lib.c

+68 −0

Original line number	Diff line number	Diff line
		@@ -996,6 +996,7 @@ int ssl_choose_server_version(SSL s, CLIENTHELLO_MSG hello)
		const version_info *vent;
		const version_info *table;
		int disabled = 0;
		RAW_EXTENSION *suppversions;

		s->client_version = client_version;

		@@ -1019,6 +1020,73 @@ int ssl_choose_server_version(SSL s, CLIENTHELLO_MSG hello)
		break;
		}

		suppversions = tls_get_extension_by_type(hello->pre_proc_exts,
		hello->num_extensions,
		TLSEXT_TYPE_supported_versions);

		/*
		* TODO(TLS1.3): We only look at this if our max protocol version is TLS1.3
		* or above. Should we allow it for lower versions too?
		*/
		if (suppversions != NULL && !SSL_IS_DTLS(s)
		&& (s->max_proto_version == 0
		\|\| TLS1_3_VERSION <= s->max_proto_version)) {
		unsigned int candidate_vers = 0;
		unsigned int best_vers = 0;
		const SSL_METHOD *best_method = NULL;
		PACKET versionslist;

		if (!PACKET_get_length_prefixed_1(&suppversions->data, &versionslist)
		\|\| PACKET_remaining(&suppversions->data) != 0) {
		/* Trailing or invalid data? */
		return SSL_R_LENGTH_MISMATCH;
		}

		while (PACKET_get_net_2(&versionslist, &candidate_vers)) {
		/* TODO(TLS1.3): Remove this before release */
		if (candidate_vers == TLS1_3_VERSION_DRAFT)
		candidate_vers = TLS1_3_VERSION;
		if ((int)candidate_vers > s->client_version)
		s->client_version = candidate_vers;
		if (version_cmp(s, candidate_vers, best_vers) <= 0)
		continue;
		for (vent = table;
		vent->version != 0 && vent->version != (int)candidate_vers;
		++vent);
		if (vent->version != 0) {
		const SSL_METHOD *method;

		method = vent->smeth();
		if (ssl_method_error(s, method) == 0) {
		best_vers = candidate_vers;
		best_method = method;
		}
		}
		}
		if (PACKET_remaining(&versionslist) != 0) {
		/* Trailing data? */
		return SSL_R_LENGTH_MISMATCH;
		}

		if (best_vers > 0) {
		s->version = best_vers;
		s->method = best_method;
		return 0;
		}
		return SSL_R_UNSUPPORTED_PROTOCOL;
		}

		/*
		* If the supported versions extension isn't present, then the highest
		* version we can negotiate is TLSv1.2
		*/
		if (version_cmp(s, client_version, TLS1_3_VERSION) >= 0)
		client_version = TLS1_2_VERSION;

		/*
		* No supported versions extension, so we just use the version supplied in
		* the ClientHello.
		*/
		for (vent = table; vent->version != 0; ++vent) {
		const SSL_METHOD *method;

ssl/t1_lib.c

+8 −7

Original line number	Diff line number	Diff line
		@@ -2826,7 +2826,7 @@ int ssl_parse_serverhello_tlsext(SSL s, PACKET pkt)
		*
		* Returns a pointer to the found RAW_EXTENSION data, or NULL if not found.
		*/
		static RAW_EXTENSION get_extension_by_type(RAW_EXTENSION exts, size_t numexts,
		RAW_EXTENSION tls_get_extension_by_type(RAW_EXTENSION exts, size_t numexts,
		unsigned int type)
		{
		size_t loop;
		@@ -2885,7 +2885,7 @@ int tls_get_ticket_from_client(SSL s, CLIENTHELLO_MSG hello,
		if (s->version <= SSL3_VERSION \|\| !tls_use_ticket(s))
		return 0;

		ticketext = get_extension_by_type(hello->pre_proc_exts,
		ticketext = tls_get_extension_by_type(hello->pre_proc_exts,
		hello->num_extensions,
		TLSEXT_TYPE_session_ticket);
		if (ticketext == NULL)
		@@ -2948,7 +2948,8 @@ int tls_check_client_ems_support(SSL s, const CLIENTHELLO_MSG hello)
		if (s->version <= SSL3_VERSION)
		return 1;

		emsext = get_extension_by_type(hello->pre_proc_exts, hello->num_extensions,
		emsext = tls_get_extension_by_type(hello->pre_proc_exts,
		hello->num_extensions,
		TLSEXT_TYPE_extended_master_secret);

		/*

test/recipes/70-test_sslvertol.t

+6 −3

Original line number	Diff line number	Diff line
		@@ -34,15 +34,18 @@ my $proxy = TLSProxy::Proxy->new(
		(!$ENV{HARNESS_ACTIVE} \|\| $ENV{HARNESS_VERBOSE})
		);

		#Test 1: Asking for TLS1.3 should pass
		my $client_version = TLSProxy::Record::VERS_TLS_1_3;
		#Test 1: Asking for TLS1.4 should pass
		my $client_version = TLSProxy::Record::VERS_TLS_1_4;
		#We don't want the supported versions extension for this test
		$proxy->clientflags("-no_tls1_3");
		$proxy->start() or plan skip_all => "Unable to start up Proxy for tests";
		plan tests => 2;
		ok(TLSProxy::Message->success(), "Version tolerance test, TLS 1.3");
		ok(TLSProxy::Message->success(), "Version tolerance test, TLS 1.4");

		#Test 2: Testing something below SSLv3 should fail
		$client_version = TLSProxy::Record::VERS_SSL_3_0 - 1;
		$proxy->clear();
		$proxy->clientflags("-no_tls1_3");
		$proxy->start();
		ok(TLSProxy::Message->fail(), "Version tolerance test, SSL < 3.0");