1#! /usr/bin/env perl
2# Copyright 2017-2021 The OpenSSL Project Authors. All Rights Reserved.
3#
4# Licensed under the Apache License 2.0 (the "License").  You may not use
5# this file except in compliance with the License.  You can obtain a copy
6# in the file LICENSE in the source distribution or at
7# https://www.openssl.org/source/license.html
8
9use strict;
10use OpenSSL::Test qw/:DEFAULT cmdstr srctop_file bldtop_dir/;
11use OpenSSL::Test::Utils;
12use TLSProxy::Proxy;
13
14my $test_name = "test_tls13downgrade";
15setup($test_name);
16
17plan skip_all => "TLSProxy isn't usable on $^O"
18    if $^O =~ /^(VMS)$/;
19
20plan skip_all => "$test_name needs the dynamic engine feature enabled"
21    if disabled("engine") || disabled("dynamic-engine");
22
23plan skip_all => "$test_name needs the sock feature enabled"
24    if disabled("sock");
25
26plan skip_all => "$test_name needs TLS1.3 and TLS1.2 enabled"
27    if disabled("tls1_3")
28       || (disabled("ec") && disabled("dh"))
29       || disabled("tls1_2");
30
31my $proxy = TLSProxy::Proxy->new(
32    undef,
33    cmdstr(app(["openssl"]), display => 1),
34    srctop_file("apps", "server.pem"),
35    (!$ENV{HARNESS_ACTIVE} || $ENV{HARNESS_VERBOSE})
36);
37
38use constant {
39    DOWNGRADE_TO_TLS_1_2 => 0,
40    DOWNGRADE_TO_TLS_1_1 => 1,
41    FALLBACK_FROM_TLS_1_3 => 2,
42};
43
44#Test 1: Downgrade from TLSv1.3 to TLSv1.2
45$proxy->filter(\&downgrade_filter);
46my $testtype = DOWNGRADE_TO_TLS_1_2;
47$proxy->start() or plan skip_all => "Unable to start up Proxy for tests";
48plan tests => 6;
49ok(TLSProxy::Message->fail(), "Downgrade TLSv1.3 to TLSv1.2");
50
51#Test 2: Downgrade from TLSv1.3 to TLSv1.1
52$proxy->clear();
53$testtype = DOWNGRADE_TO_TLS_1_1;
54$proxy->start();
55ok(TLSProxy::Message->fail(), "Downgrade TLSv1.3 to TLSv1.1");
56
57#Test 3: Downgrade from TLSv1.2 to TLSv1.1
58$proxy->clear();
59$proxy->clientflags("-no_tls1_3");
60$proxy->serverflags("-no_tls1_3");
61$proxy->start();
62ok(TLSProxy::Message->fail(), "Downgrade TLSv1.2 to TLSv1.1");
63
64#Test 4: Client falls back from TLSv1.3 (server does not support the fallback
65#        SCSV)
66$proxy->clear();
67$testtype = FALLBACK_FROM_TLS_1_3;
68$proxy->clientflags("-fallback_scsv -no_tls1_3");
69$proxy->start();
70my $alert = TLSProxy::Message->alert();
71ok(TLSProxy::Message->fail()
72   && !$alert->server()
73   && $alert->description() == TLSProxy::Message::AL_DESC_ILLEGAL_PARAMETER,
74   "Fallback from TLSv1.3");
75
76SKIP: {
77    skip "TLSv1.1 disabled", 2 if disabled("tls1_1");
78    #Test 5: A client side protocol "hole" should not be detected as a downgrade
79    $proxy->clear();
80    $proxy->filter(undef);
81    $proxy->clientflags("-no_tls1_2");
82    $proxy->ciphers("AES128-SHA:\@SECLEVEL=0");
83    $proxy->start();
84    ok(TLSProxy::Message->success(), "TLSv1.2 client-side protocol hole");
85
86    #Test 6: A server side protocol "hole" should not be detected as a downgrade
87    $proxy->clear();
88    $proxy->filter(undef);
89    $proxy->serverflags("-no_tls1_2");
90    $proxy->start();
91    ok(TLSProxy::Message->success(), "TLSv1.2 server-side protocol hole");
92}
93
94sub downgrade_filter
95{
96    my $proxy = shift;
97
98    # We're only interested in the initial ClientHello
99    if ($proxy->flight != 0) {
100        return;
101    }
102
103    my $message = ${$proxy->message_list}[0];
104
105    my $ext;
106    if ($testtype == FALLBACK_FROM_TLS_1_3) {
107        #The default ciphersuite we use for TLSv1.2 without any SCSV
108        my @ciphersuites = (TLSProxy::Message::CIPHER_RSA_WITH_AES_128_CBC_SHA);
109        $message->ciphersuite_len(2 * scalar @ciphersuites);
110        $message->ciphersuites(\@ciphersuites);
111    } else {
112        if ($testtype == DOWNGRADE_TO_TLS_1_2) {
113            $ext = pack "C3",
114                0x02, # Length
115                0x03, 0x03; #TLSv1.2
116        } else {
117            $ext = pack "C3",
118                0x02, # Length
119                0x03, 0x02; #TLSv1.1
120        }
121
122        $message->set_extension(TLSProxy::Message::EXT_SUPPORTED_VERSIONS, $ext);
123    }
124
125    $message->repack();
126}
127
128