From 0dd6a96ce1bf2cef9140d01a5c49eb92e2f8ec6f Mon Sep 17 00:00:00 2001
From: Guilhem Moulin <guilhem@fripost.org>
Date: Mon, 4 Nov 2013 07:27:10 +0100
Subject: Be more specific regarding the protocol in use for IPSec policies.
We use ESP only, so other protocols shouldn't be ACCEPTed.
---
roles/common/files/etc/network/if-up.d/ipsec | 5 +++-
.../common/files/usr/local/sbin/update-firewall.sh | 30 ++++++++++++----------
2 files changed, 21 insertions(+), 14 deletions(-)
(limited to 'roles/common/files')
diff --git a/roles/common/files/etc/network/if-up.d/ipsec b/roles/common/files/etc/network/if-up.d/ipsec
index 98bf42c..a43af6c 100755
--- a/roles/common/files/etc/network/if-up.d/ipsec
+++ b/roles/common/files/etc/network/if-up.d/ipsec
@@ -40,7 +40,10 @@ case "$MODE" in
# If a packet retained its mark that far, it means it has
# been SNAT'ed from $ipsec, and didn't have a xfrm
- # association. Hence we nullroute it to avoid leaking data.
+ # association. Hence we nullroute it to avoid to leak data
+ # intented to be tunneled through IPSec. /!\ The priority
+ # must be >220 (strongSwan IPSec's policy) since xfrm lookup
+ # must take precedence.
/bin/ip rule add fwmark "$secmark" table 666 priority 666 || true
/bin/ip route add prohibit default table 666 || true
;;
diff --git a/roles/common/files/usr/local/sbin/update-firewall.sh b/roles/common/files/usr/local/sbin/update-firewall.sh
index 0907ffc..1c57646 100755
--- a/roles/common/files/usr/local/sbin/update-firewall.sh
+++ b/roles/common/files/usr/local/sbin/update-firewall.sh
@@ -30,8 +30,11 @@ check=0
verbose=0
addrfam=
+secmark=0xA99 # must match that in /etc/network/if-up.d/ipsec
+secproto=esp # must match /etc/ipsec.conf; ESP is the default (vs AH/IPComp)
+
fail2ban_re='^(\[[0-9]+:[0-9]+\]\s+)?-A fail2ban-\S'
-IPSec_re=' -m policy --dir (in|out) --pol ipsec .* --proto esp -j ACCEPT$'
+IPSec_re=" -m policy --dir (in|out) --pol ipsec .* --proto $secproto -j ACCEPT$"
declare -A rss=() tables=()
usage() {
@@ -147,13 +150,11 @@ run() {
| sed -nr "/^[0-9]+:\s+(sec[0-9]+)@$if:\s.*/ {s//\1/p;q}" )
# The (host-scoped) IP reserved for IPSec.
- local ipsec= secmark
+ local ipsec=
if [ -n "$ifsec" -a $f = 4 ]; then
tables[$f]='mangle nat filter'
ipsec=$( /bin/ip -$f address show dev "$ifsec" scope host \
| sed -nr '/^\s+inet\s(\S+).*/ {s//\1/p;q}' )
- # /!\ This mark much match that in /etc/network/if-up.d/ipsec.
- secmark=0xA99
fi
# Store the old (current) ruleset
@@ -196,9 +197,9 @@ run() {
# (Host-to-host) IPSec tunnels come first. TODO: test IPSec with IPv6.
grep -E -- "$IPSec_re" "$old" >> "$new" || true
- # Allow any IPsec ESP protocol packets to be sent and received.
- iptables -A INPUT -i $if -p esp -j ACCEPT
- iptables -A OUTPUT -o $if -p esp -j ACCEPT
+ # Allow any IPsec $secproto protocol packets to be sent and received.
+ iptables -A INPUT -i $if -p $secproto -j ACCEPT
+ iptables -A OUTPUT -o $if -p $secproto -j ACCEPT
fi
@@ -252,7 +253,8 @@ run() {
# ACCEPT any, *IPSec* traffic destinating to the non-routable
# $ipsec. Also ACCEPT all traffic originating from $ipsec, as
# it is MASQUERADE'd.
- iptables -A INPUT -d "$ipsec" -i $if -m policy --dir in --pol ipsec -j ACCEPT
+ iptables -A INPUT -d "$ipsec" -i $if -m policy --dir in \
+ --pol ipsec --proto $secproto -j ACCEPT
iptables -A OUTPUT -m mark --mark "$secmark" -o $if -j ACCEPT
fi
@@ -327,23 +329,25 @@ run() {
# Packets which destination is $ipsec *must* be associated with
# an IPSec policy.
- iptables -A INPUT -d "$ipsec" -i $if -m policy --dir in --pol none -j DROP
+ iptables -A INPUT -d "$ipsec" -i $if -m policy --dir in \
+ --pol ipsec --proto $secproto -j ACCEPT
+ iptables -A INPUT -d "$ipsec" -i $if -j DROP
# Packets originating from our (non-routable) $ipsec are marked;
# if there is no xfrm lookup (i.e., no matching IPSec
# association), the packet will retain its mark and be null
# routed later on. Otherwise, the packet is re-queued unmarked.
iptables -A OUTPUT -o $if -j MARK --set-mark 0x0
- iptables -A OUTPUT -s "$ipsec" -o $if -m policy --dir out --pol none \
- -j MARK --set-mark $secmark
+ iptables -A OUTPUT -s "$ipsec" -o $if -m policy --dir out \
+ --pol none -j MARK --set-mark $secmark
commit
ipt-chains nat PREROUTING:ACCEPT INPUT:ACCEPT \
OUTPUT:ACCEPT POSTROUTING:ACCEPT
# DNAT all marked packets after decapsulation.
- iptables -A PREROUTING \! -d "$ipsec" -i $if \
- -m policy --dir in --pol ipsec -j DNAT --to "${ipsec%/*}"
+ iptables -A PREROUTING \! -d "$ipsec" -i $if -m policy --dir in \
+ --pol ipsec --proto $secproto -j DNAT --to "${ipsec%/*}"
# Packets originating from our IPSec are SNAT'ed (MASQUERADE).
# (And null-routed later on unless there is an xfrm
--
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