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 => "$test_name needs TLSv1.2 enabled"
29    if disabled("tls1_2");
30
31$ENV{OPENSSL_ia32cap} = '~0x200000200000000';
32my $proxy = TLSProxy::Proxy->new(
33    \&add_maximal_padding_filter,
34    cmdstr(app(["openssl"]), display => 1),
35    srctop_file("apps", "server.pem"),
36    (!$ENV{HARNESS_ACTIVE} || $ENV{HARNESS_VERBOSE})
37);
38
39# TODO: We could test all 256 values, but then the log file gets too large for
40# CI. See https://github.com/openssl/openssl/issues/1440.
41my @test_offsets = (0, 128, 254, 255);
42
43# Test that maximally-padded records are accepted.
44my $bad_padding_offset = -1;
45$proxy->serverflags("-tls1_2");
46$proxy->clientflags("-no_tls1_3");
47$proxy->serverconnects(1 + scalar(@test_offsets));
48$proxy->start() or plan skip_all => "Unable to start up Proxy for tests";
49plan tests => 1 + scalar(@test_offsets);
50ok(TLSProxy::Message->success(), "Maximally-padded record test");
51
52# Test that invalid padding is rejected.
53my $fatal_alert;    # set by add_maximal_padding_filter on client's fatal alert
54
55foreach my $offset (@test_offsets) {
56    $bad_padding_offset = $offset;
57    $fatal_alert = 0;
58    $proxy->clearClient();
59    $proxy->clientflags("-no_tls1_3");
60    $proxy->clientstart();
61    ok($fatal_alert, "Invalid padding byte $bad_padding_offset");
62}
63
64sub add_maximal_padding_filter
65{
66    my $proxy = shift;
67    my $messages = $proxy->message_list;
68    state $sent_corrupted_payload;
69
70    if ($proxy->flight == 0) {
71        # Disable Encrypt-then-MAC.
72        foreach my $message (@{$messages}) {
73            if ($message->mt != TLSProxy::Message::MT_CLIENT_HELLO) {
74                next;
75            }
76
77            $message->delete_extension(TLSProxy::Message::EXT_ENCRYPT_THEN_MAC);
78            $message->process_extensions();
79            $message->repack();
80        }
81        $sent_corrupted_payload = 0;
82        return;
83    }
84
85    my $last_message = @{$messages}[-1];
86    if (defined($last_message)
87        && $last_message->server
88        && $last_message->mt == TLSProxy::Message::MT_FINISHED
89        && !@{$last_message->records}[0]->{sent}) {
90
91        # Insert a maximally-padded record. Assume a block size of 16 (AES) and
92        # a MAC length of 20 (SHA-1).
93        my $block_size = 16;
94        my $mac_len = 20;
95
96        # Size the plaintext so that 256 is a valid padding.
97        my $plaintext_len = $block_size - ($mac_len % $block_size);
98        my $plaintext = "A" x $plaintext_len;
99
100        my $data = "B" x $block_size; # Explicit IV.
101        $data .= $plaintext;
102        $data .= TLSProxy::Proxy::fill_known_data($mac_len); # MAC.
103
104        # Add padding.
105        for (my $i = 0; $i < 256; $i++) {
106            if ($i == $bad_padding_offset) {
107                $sent_corrupted_payload = 1;
108                $data .= "\xfe";
109            } else {
110                $data .= "\xff";
111            }
112        }
113
114        my $record = TLSProxy::Record->new(
115            $proxy->flight,
116            TLSProxy::Record::RT_APPLICATION_DATA,
117            TLSProxy::Record::VERS_TLS_1_2,
118            length($data),
119            0,
120            length($data),
121            $plaintext_len,
122            $data,
123            $plaintext,
124        );
125
126        # Send the record immediately after the server Finished.
127        push @{$proxy->record_list}, $record;
128    } elsif ($sent_corrupted_payload) {
129        # Check for bad_record_mac from client
130        my $last_record = @{$proxy->record_list}[-1];
131        $fatal_alert = 1 if $last_record->is_fatal_alert(0) == 20;
132    }
133}
134