1 files changed, 47 insertions, 0 deletions
diff --git a/roles/common/templates/etc/network/if-up.d/ipsec.j2 b/roles/common/templates/etc/network/if-up.d/ipsec.j2
new file mode 100755
index 0000000..7dd41d4
--- /dev/null
+++ b/roles/common/templates/etc/network/if-up.d/ipsec.j2
@@ -0,0 +1,47 @@
+#!/bin/sh
+
+# A post-up/down hook to automatically create/delete a virtual subnet
+# for IPSec (inet4 only).
+# Copyright © 2016 Guilhem Moulin <guilhem@fripost.org>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+set -ue
+PATH=/usr/sbin:/usr/bin:/sbin:/bin
+
+# Ignore the loopback interface and non inet4 families.
+[ "$IFACE" != lo -a "$ADDRFAM" = inet ] || exit 0
+
+# Only the device with the default, globally-scoped route, is of
+# interest here.
+ip="$( ip -4 -o route show to default scope global \
+     | sed -nr '/^default via (\S+) dev (\S+).*/ {s//\2 \1/p;q}' )"
+[ "${ip% *}" = "$IFACE" ] || exit 0
+ip="${ip##* }"
+
+vip="{{ ipsec[inventory_hostname_short] }}"
+vsubnet="{{ ipsec_subnet }}"
+
+case "$MODE" in
+    start) ip address add "$vip/32" dev "$IFACE" scope global || true
+           # Nullroute the subnet used for IPSec to avoid data leaks
+           # in the absence of xfrm lookup (i.e., when there is no
+           # matching IPSec Security Association).
+           ip route replace prohibit "$vsubnet" proto static || true
+           ip route replace table 220 to "$vsubnet" via "$ip" dev "$IFACE" proto static src "$vip" || true
+    ;;
+    stop)  ip route del table 220 to "$vsubnet" via "$ip" dev "$IFACE" proto static src "$vip" || true
+           ip route del prohibit "$vsubnet" proto static || true
+           ip address del "$vip/32" dev "$IFACE" scope global || true
+esac