From: Jonathan McDowell <noodles@earth.li>
Date: Wed, 15 Jun 2005 10:41:54 +0000 (+0000)
Subject: cscvs to tla changeset 14
X-Git-Url: https://the.earth.li/gitweb/?a=commitdiff_plain;h=b3a4e4c944a9535aaf39fe414d76171b4169bd6b;p=autodns.git

cscvs to tla changeset 14

Author: noodles
Date: 2005/06/15 10:14:28
Add checking of signature time, to try to limit replay attacks.

git-archimport-id: noodles@earth.li--pie/autodns--mainline--1.0--patch-13
---

diff --git a/autodns.conf b/autodns.conf
index b320c27..56e09f8 100644
--- a/autodns.conf
+++ b/autodns.conf
@@ -29,3 +29,9 @@ $lockfile="/etc/bind/autodns.lck";
 
 # The command to reload the nameserver domains list.
 $reload_command="sudo ndc reconfig 2>&1";
+
+# When we consider a signature to have expired and so to be rejected.
+# Intended to help prevent reply attacks. Value is in seconds and the 
+# signature can be +/- this many seconds from current time before being
+# rejected.
+$expiry = 7200;
diff --git a/autodns.pl b/autodns.pl
index d017e60..5aba950 100755
--- a/autodns.pl
+++ b/autodns.pl
@@ -5,10 +5,11 @@
 # http://www.earth.li/projectpurple/progs/autodns.html
 # Released under the GPL.
 #
-# $Id: autodns.pl,v 1.13 2005/05/31 17:17:46 noodles Exp $
+# $Id: autodns.pl,v 1.14 2005/06/15 10:14:28 noodles Exp $
 #
 
 use strict;
+use Date::Parse;
 use Fcntl qw(:flock);
 use File::Temp qw(tempfile);
 use IPC::Open3;
@@ -21,7 +22,7 @@ my ($user, $server, $inprocess, $delcount, $addcount);
 my ($domain, @MAIL, @GPGERROR, @COMMANDS, %zones, $VERSION);
 
 use vars qw($me $ccreply $conffile $domainlistroot @cfgfiles $usersfile
-	$lockfile $reload_command);
+	$lockfile $reload_command $expiry);
 
 $VERSION="0.0.8";
 
@@ -267,10 +268,12 @@ if ($entity->parts) {
 
 # Check who it's from and if the signature was a good one.
 $gpggood=1;
+my $sigtime = 0;
 foreach (@GPGERROR) {
 	chomp;
-	if (/Signature made.* (.*)$/) {
-		$gpguser=$1; 
+	if (/Signature made (.*) using.*ID (.*)$/) {
+		$sigtime = str2time($1);
+		$gpguser=$2; 
 	} elsif (/error/) {
 		$gpggood = 0;
 		print REPLY "Some errors ocurred\n";
@@ -299,6 +302,21 @@ if ($gpggood) {
 	exit;
 }
 
+# Check if the signature is outside our acceptable range.
+if (!defined($sigtime)) {
+	print REPLY "Couldn't parse signature time.\n";
+	close REPLY;
+	exit;
+} elsif ($sigtime > (time + $expiry)) {
+	print REPLY "Signature too far into the future.\n";
+	close REPLY;
+	exit;
+} elsif ($sigtime < (time - $expiry)) {
+	print REPLY "Signature too far into the past.\n";
+	close REPLY;
+	exit;
+}
+
 # Now let's check if we know this person.
 ($user, $priv, $server) = getuserinfo($gpguser);