1#! /usr/bin/env perl
2# Copyright 2016-2021 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 feature 'state';
11
12use OpenSSL::Test qw/:DEFAULT cmdstr srctop_file bldtop_dir/;
13use OpenSSL::Test::Utils;
14use TLSProxy::Proxy;
15
16my $test_name = "test_sslcbcpadding";
17setup($test_name);
18
19plan skip_all => "TLSProxy isn't usable on $^O"
20    if $^O =~ /^(VMS)$/;
21
22plan skip_all => "$test_name needs the dynamic engine feature enabled"
23    if disabled("engine") || disabled("dynamic-engine");
24
25plan skip_all => "$test_name needs the sock feature enabled"
26    if disabled("sock");
27
28plan skip_all => "$test_name needs TLSv1.2 enabled"
29    if disabled("tls1_2");
30
31my $proxy = TLSProxy::Proxy->new(
32    \&add_maximal_padding_filter,
33    cmdstr(app(["openssl"]), display => 1),
34    srctop_file("apps", "server.pem"),
35    (!$ENV{HARNESS_ACTIVE} || $ENV{HARNESS_VERBOSE})
36);
37
38# TODO: We could test all 256 values, but then the log file gets too large for
39# CI. See https://github.com/openssl/openssl/issues/1440.
40my @test_offsets = (0, 128, 254, 255);
41
42# Test that maximally-padded records are accepted.
43my $bad_padding_offset = -1;
44$proxy->serverflags("-tls1_2");
45$proxy->clientflags("-no_tls1_3");
46$proxy->serverconnects(1 + scalar(@test_offsets));
47$proxy->start() or plan skip_all => "Unable to start up Proxy for tests";
48plan tests => 1 + scalar(@test_offsets);
49ok(TLSProxy::Message->success(), "Maximally-padded record test");
50
51# Test that invalid padding is rejected.
52my $fatal_alert;    # set by add_maximal_padding_filter on client's fatal alert
53
54foreach my $offset (@test_offsets) {
55    $bad_padding_offset = $offset;
56    $fatal_alert = 0;
57    $proxy->clearClient();
58    $proxy->clientflags("-no_tls1_3");
59    $proxy->clientstart();
60    ok($fatal_alert, "Invalid padding byte $bad_padding_offset");
61}
62
63sub add_maximal_padding_filter
64{
65    my $proxy = shift;
66    my $messages = $proxy->message_list;
67    state $sent_corrupted_payload;
68
69    if ($proxy->flight == 0) {
70        # Disable Encrypt-then-MAC.
71        foreach my $message (@{$messages}) {
72            if ($message->mt != TLSProxy::Message::MT_CLIENT_HELLO) {
73                next;
74            }
75
76            $message->delete_extension(TLSProxy::Message::EXT_ENCRYPT_THEN_MAC);
77            $message->process_extensions();
78            $message->repack();
79        }
80        $sent_corrupted_payload = 0;
81        return;
82    }
83
84    my $last_message = @{$messages}[-1];
85    if (defined($last_message)
86        && $last_message->server
87        && $last_message->mt == TLSProxy::Message::MT_FINISHED
88        && !@{$last_message->records}[0]->{sent}) {
89
90        # Insert a maximally-padded record. Assume a block size of 16 (AES) and
91        # a MAC length of 20 (SHA-1).
92        my $block_size = 16;
93        my $mac_len = 20;
94
95        # Size the plaintext so that 256 is a valid padding.
96        my $plaintext_len = $block_size - ($mac_len % $block_size);
97        my $plaintext = "A" x $plaintext_len;
98
99        my $data = "B" x $block_size; # Explicit IV.
100        $data .= $plaintext;
101        $data .= TLSProxy::Proxy::fill_known_data($mac_len); # MAC.
102
103        # Add padding.
104        for (my $i = 0; $i < 256; $i++) {
105            if ($i == $bad_padding_offset) {
106                $sent_corrupted_payload = 1;
107                $data .= "\xfe";
108            } else {
109                $data .= "\xff";
110            }
111        }
112
113        my $record = TLSProxy::Record->new(
114            $proxy->flight,
115            TLSProxy::Record::RT_APPLICATION_DATA,
116            TLSProxy::Record::VERS_TLS_1_2,
117            length($data),
118            0,
119            length($data),
120            $plaintext_len,
121            $data,
122            $plaintext,
123        );
124
125        # Send the record immediately after the server Finished.
126        push @{$proxy->record_list}, $record;
127    } elsif ($sent_corrupted_payload) {
128        # Check for bad_record_mac from client
129        my $last_record = @{$proxy->record_list}[-1];
130        $fatal_alert = 1 if $last_record->is_fatal_alert(0) == 20;
131    }
132}
133