firewall: call iptables-restore once per domain (#311)

qubes.py now places rules for each domain in a separate key under
/local/domain/fw_XID/qubes_iptables_domainrules/
plus the header in /local/domain/fw_XID/qubes_iptables_header.
/local/domain/fw_XID/qubes_iptables is now just a trigger.
So, if iptables-restore fails dues to e.g. error resolving a domain name
in a rules for a domain, then only this domain will not get connectivity,
others will work fine.

dom0/qvm-core/qubes.py

@@ -1459,6 +1459,7 @@ class QubesProxyVm(QubesNetVm):
                 "{0}".format(self.netvm_vm.get_xid()))
 
     def write_iptables_xenstore_entry(self):
+        xs.rm('', "/local/domain/{0}/qubes_iptables_domainrules".format(self.get_xid()))
         iptables =  "# Generated by Qubes Core on {0}\n".format(datetime.now().ctime())
         iptables += "*filter\n"
         iptables += ":INPUT DROP [0:0]\n"
@@ -1477,9 +1478,12 @@ class QubesProxyVm(QubesNetVm):
         iptables += "-A FORWARD -i vif0.0 -j ACCEPT\n"
         # Deny inter-VMs networking
         iptables += "-A FORWARD -i vif+ -o vif+ -j DROP\n"
+        iptables += "COMMIT\n"
+        xs.write('', "/local/domain/{0}/qubes_iptables_header".format(self.get_xid()), iptables)
 
         vms = [vm for vm in self.connected_vms.values()]
         for vm in vms:
+            iptables="*filter\n"
             if vm.has_firewall():
                 conf = vm.get_firewall_conf()
             else:
@@ -1522,16 +1526,14 @@ class QubesProxyVm(QubesNetVm):
                 iptables += "-A FORWARD -i vif{0}.+ -p icmp -j ACCEPT\n".format(xid)
 
             iptables += "-A FORWARD -i vif{0}.+ -j {1}\n".format(xid, default_action)
-
+            iptables += "COMMIT\n"
-        iptables += "#End of VM rules\n"
+            xs.write('', "/local/domain/"+str(self.get_xid())+"/qubes_iptables_domainrules/"+str(xid), iptables)
-        iptables += "-A FORWARD -j DROP\n"
+        # no need for ending -A FORWARD -j DROP, cause default action is DROP
-
-        iptables += "COMMIT"
 
         self.write_netvm_domid_entry()
 
         self.rules_applied = None
-        xs.write('', "/local/domain/{0}/qubes_iptables".format(self.get_xid()), iptables)
+        xs.write('', "/local/domain/{0}/qubes_iptables".format(self.get_xid()), 'reload')
 
     def get_xml_attrs(self):
         attrs = super(QubesProxyVm, self).get_xml_attrs()

proxyvm/bin/qubes_firewall

@@ -3,9 +3,9 @@ set -e
 
 PIDFILE=/var/run/qubes/qubes_firewall.pid
 XENSTORE_IPTABLES=qubes_iptables
+XENSTORE_IPTABLES_HEADER=qubes_iptables_header
 XENSTORE_ERROR=qubes_iptables_error
 OLD_RULES=""
-
 # PIDfile handling
 [[ -e $PIDFILE ]] && kill -s 0 $(<$PIDFILE) 2>/dev/null && exit 0
 echo $$ >$PIDFILE
@@ -13,24 +13,26 @@ echo $$ >$PIDFILE
 trap 'exit 0' SIGTERM
 
 while true; do
-	RULES=$(/usr/bin/xenstore-read $XENSTORE_IPTABLES)
-
-	if [[ "$RULES" != "$OLD_RULES" ]]; then
-		IPTABLES_SAVE=$(/sbin/iptables-save | sed '/^\*filter/,/^COMMIT/d')
-		OUT=`echo -e "$RULES\n$IPTABLES_SAVE" | /sbin/iptables-restore 2>&1 || :`
-		/usr/bin/xenstore-write $XENSTORE_ERROR "$OUT"
-		if [ "$OUT" ]; then
-			DISPLAY=:0 /usr/bin/notify-send -t 3000 "Firewall loading error ($HOSTNAME)" "$OUT" || :
-		fi
-
-		if [[ -z "$OUT" ]]; then
-			# If OK save it for later
-			/sbin/service iptables save >/dev/null
-		fi
-
-		OLD_RULES="$RULES"
-	fi
-
 	# Wait for changes in xenstore file
 	/usr/bin/xenstore-watch-qubes $XENSTORE_IPTABLES
+	TRIGGER=$(/usr/bin/xenstore-read $XENSTORE_IPTABLES)
+
+	if ! [ "$TRIGGER" = "reload" ]; then continue ; fi
+	RULES=$(/usr/bin/xenstore-read $XENSTORE_IPTABLES_HEADER)
+	IPTABLES_SAVE=$(/sbin/iptables-save | sed '/^\*filter/,/^COMMIT/d')
+	OUT=`echo -e "$RULES\n$IPTABLES_SAVE" | /sbin/iptables-restore 2>&1 || :`
+
+	for i in $(xenstore-list qubes_iptables_domainrules) ; do 
+		RULES=$(/usr/bin/xenstore-read qubes_iptables_domainrules/"$i")
+		ERRS=`echo -e "$RULES" | /sbin/iptables-restore -n 2>&1 || :`
+		OUT="$OUT""$ERRS"
+	done		
+	/usr/bin/xenstore-write $XENSTORE_ERROR "$OUT"
+	if [ "$OUT" ]; then
+		DISPLAY=:0 /usr/bin/notify-send -t 3000 "Firewall loading error ($HOSTNAME)" "$OUT" || :
+	fi
+	if [[ -z "$OUT" ]]; then
+		# If OK save it for later
+		/sbin/service iptables save >/dev/null
+	fi
 done