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authorGuilhem Moulin <guilhem@fripost.org>2013-11-04 00:31:43 +0100
committerGuilhem Moulin <guilhem@fripost.org>2015-06-07 02:50:38 +0200
commit67c5135625d3553dcb6f2bfc193df24c0e1ab826 (patch)
tree21d5c3c18a1531e445cd1c0dad9ac76a358f7321 /roles/common/files/etc/network
parentad9c840c40d923e0fd1b04a57274cc2ec2e381ec (diff)
Prohibit binding against the IP reserved for IPSec.
Packets originating from our (non-routable) $ipsec are marked; there is no xfrm lookup (i.e., no matching IPSec association), the packet will retain its mark and be null routed later on, thanks to ip rule add fwmark "$secmark" table 666 priority 666 ip route add blackhole default table 666
Diffstat (limited to 'roles/common/files/etc/network')
-rwxr-xr-xroles/common/files/etc/network/if-up.d/ipsec44
1 files changed, 28 insertions, 16 deletions
diff --git a/roles/common/files/etc/network/if-up.d/ipsec b/roles/common/files/etc/network/if-up.d/ipsec
index e21d6ea..98bf42c 100755
--- a/roles/common/files/etc/network/if-up.d/ipsec
+++ b/roles/common/files/etc/network/if-up.d/ipsec
@@ -11,8 +11,11 @@
set -ue
PATH=/usr/sbin:/usr/bin:/sbin:/bin
-if=sec0
-ip=172.16.0.1/32
+ifsec=sec0
+ipsec=172.16.0.1/32
+
+# /!\ This mark much match that in /usr/local/sbin/update-firewall.sh.
+secmark=0xA99
# Ignore the loopback interface and non inet4 families.
[ "$IFACE" != lo -a "$ADDRFAM" = inet ] || exit 0
@@ -25,20 +28,29 @@ ip=172.16.0.1/32
"$IFACE" ] || exit 0
case "$MODE" in
- start) # Don't create $if if it's already there
- /bin/ip -o link show | grep -qE "^[0-9]+:\s+$if" && exit 0
-
- # Create a new VLAN $IFACE on physical device $if. This is
- # required otherwise charon thinks the left peer is that
- # host-scoped, non-routable IP.
- /bin/ip link add link "$IFACE" name "$if" type vlan id 2713
- /bin/ip address add "$ip" dev "$if" scope host
- /bin/ip link set dev "$if" up
+ start) # Don't create $ifsec if it's already there
+ if ! /bin/ip -o link show | grep -qE "^[0-9]+:\s+$ifsec"; then
+ # Create a new VLAN $IFACE on physical device $ifsec. This is
+ # required otherwise charon thinks the left peer is that
+ # host-scoped, non-routable IP.
+ /bin/ip link add link "$IFACE" name "$ifsec" type vlan id 2713
+ /bin/ip address add "$ipsec" dev "$ifsec" scope host
+ /bin/ip link set dev "$ifsec" up
+ fi
+
+ # If a packet retained its mark that far, it means it has
+ # been SNAT'ed from $ipsec, and didn't have a xfrm
+ # association. Hence we nullroute it to avoid leaking data.
+ /bin/ip rule add fwmark "$secmark" table 666 priority 666 || true
+ /bin/ip route add prohibit default table 666 || true
;;
- stop) # Don't create $if if it's no there
- /bin/ip -o link show | grep -qE "^[0-9]+:\s+$if" || exit 0
-
- # Deactivate the VLAN
- /bin/ip link set dev "$if" down
+ stop) if /bin/ip -o link show | grep -qE "^[0-9]+:\s+$ifsec"; then
+ # Deactivate the VLAN
+ /bin/ip link set dev "$ifsec" down
+ fi
+
+ # Delete the 'prohibit' rule
+ /bin/ip rule del fwmark "$secmark" table 666 priority 666 || true
+ /bin/ip route flush table 666
;;
esac