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Teach TLSProxy how to encrypt <= TLSv1.2 ETM records

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Previously TLSProxy only knew how to "repack" messages for TLSv1.3.
Most of the handshake in <= TLSv1.2 is unencrypted so this hasn't been
too much of restriction. However we now want to modify reneg handshakes
which are encrypted so we need to add that capability.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
This commit is contained in:
Matt Caswell 2021-03-18 15:25:42 +00:00
parent eb78f95523
commit ae937a096c
1 changed files with 30 additions and 7 deletions
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37
util/perl/TLSProxy/Message.pm
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@ -448,7 +448,7 @@ sub ciphersuite
}
#Update all the underlying records with the modified data from this message
#Note: Only supports re-encrypting for TLSv1.3
#Note: Only supports TLSv1.3 and ETM encryption
sub repack
{
my $self = shift;
@ -490,15 +490,38 @@ sub repack
# (If a length override is ever needed to construct invalid packets,
# use an explicit override field instead.)
$rec->decrypt_len(length($rec->decrypt_data));
$rec->len($rec->len + length($msgdata) - $old_length);
# Only support re-encryption for TLSv1.3.
if (TLSProxy::Proxy->is_tls13() && $rec->encrypted()) {
#Add content type (1 byte) and 16 tag bytes
$rec->data($rec->decrypt_data
.pack("C", TLSProxy::Record::RT_HANDSHAKE).("\0"x16));
# Only support re-encryption for TLSv1.3 and ETM.
if ($rec->encrypted()) {
if (TLSProxy::Proxy->is_tls13()) {
#Add content type (1 byte) and 16 tag bytes
$rec->data($rec->decrypt_data
.pack("C", TLSProxy::Record::RT_HANDSHAKE).("\0"x16));
} elsif ($rec->etm()) {
my $data = $rec->decrypt_data;
#Add padding
my $padval = length($data) % 16;
$padval = 15 - $padval;
for (0..$padval) {
$data .= pack("C", $padval);
}
#Add MAC. Assumed to be 20 bytes
foreach my $macval (0..19) {
$data .= pack("C", $macval);
}
if ($rec->version() >= TLSProxy::Record::VERS_TLS_1_1) {
#Explicit IV
$data = ("\0"x16).$data;
}
$rec->data($data);
} else {
die "Unsupported encryption: No ETM";
}
} else {
$rec->data($rec->decrypt_data);
}
$rec->len(length($rec->data));
#Update the fragment len in case we changed it above
${$self->message_frag_lens}[0] = length($msgdata)