From: Mark Wooding <mdw@distorted.org.uk>
Date: Mon, 2 Oct 2017 01:01:35 +0000 (+0100)
Subject: local.m4: Filter out source routing in the firewall.
X-Git-Url: https://git.distorted.org.uk/~mdw/firewall/commitdiff_plain/7377aca7bc3d4cfd29e6974c861048db8e1a4161

local.m4: Filter out source routing in the firewall.

Don't rely on `sysctl' options.  This means that everyone must now have
`xtables-addons' installed.
---

diff --git a/local.m4 b/local.m4
index c16f94e..821cea9 100644
--- a/local.m4
+++ b/local.m4
@@ -354,6 +354,23 @@ case $forward in
     ;;
 esac
 
+m4_divert(82)m4_dnl
+###--------------------------------------------------------------------------
+### Check for source routing.
+
+clearchain check-srcroute
+
+run iptables -A check-srcroute -g forbidden \
+    -m ipv4options --any --flags lsrr,ssrr
+run ip6tables -A check-srcroute -g forbidden \
+    -m rt
+
+for c in INPUT FORWARD; do
+  for m in $from_scary $from_untrusted; do
+    run ip46tables -A $c -m mark --mark $m/$MASK_FROM -j check-srcroute
+  done
+done
+
 m4_divert(84)m4_dnl
 ###--------------------------------------------------------------------------
 ### Locally-bound packet inspection.