firewall changes:

 - implement a REJECT policy and enable it by default, reject packets with approriate response (closes: #3970)
 - cleanup syn_flood and remove logging

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@12688 3c298f89-4303-0410-b956-a3cf2f4a3e73

diff --git a/package/firewall/files/firewall.config b/package/firewall/files/firewall.config
index fe5d38d2b9c271ed939a028cd7d3e99b036a85a1..8ac9049553daf6c914b23df629ad5dae3ab81413 100755 (executable)
--- a/package/firewall/files/firewall.config
+++ b/package/firewall/files/firewall.config
@@ -1,20 +1,20 @@
 config defaults
        option syn_flood        1
-       option input            DROP 
+       option input            REJECT
        option output           ACCEPT 
-       option forward          DROP 
+       option forward          REJECT
 
 config zone
        option name             lan
        option input    ACCEPT 
        option output   ACCEPT 
-       option forward  DROP 
+       option forward  REJECT
 
 config zone
        option name             wan
-       option input    DROP 
+       option input    REJECT
        option output   ACCEPT 
-       option forward  DROP 
+       option forward  REJECT
        option masq             1 
 
 config forwarding 

diff --git a/package/firewall/files/uci_firewall.sh b/package/firewall/files/uci_firewall.sh
index 22731af98e6f6e9b82e8b593772ed87529020322..884b596391a9fa57d3c7821ba34a088b366b140b 100755 (executable)
--- a/package/firewall/files/uci_firewall.sh
+++ b/package/firewall/files/uci_firewall.sh
@@ -46,7 +46,7 @@ create_zone() {
        $IPTABLES -N zone_$1_forward
        $IPTABLES -A zone_$1_forward -j zone_$1_$5
        $IPTABLES -A zone_$1 -j zone_$1_$3
-       $IPTABLES -A OUTPUT -j zone_$1_$4
+       $IPTABLES -A output -j zone_$1_$4
        $IPTABLES -N zone_$1_nat -t nat
        $IPTABLES -N zone_$1_prerouting -t nat
        [ "$6" == "1" ] && $IPTABLES -t nat -A POSTROUTING -j zone_$1_nat
@@ -58,43 +58,52 @@ addif() {
        [ -n "$dev" -a "$dev" != "$1" ] && delif "$dev" "$2"
        [ -n "$dev" -a "$dev" == "$1" ] && return
        logger "adding $1 to firewall zone $2"
-       $IPTABLES -A INPUT -i $1 -j zone_$2
+       $IPTABLES -A input -i $1 -j zone_$2
        $IPTABLES -I zone_$2_ACCEPT 1 -o $1 -j ACCEPT
        $IPTABLES -I zone_$2_DROP 1 -o $1 -j DROP
-       $IPTABLES -I zone_$2_REJECT 1 -o $1 -j REJECT
+       $IPTABLES -I zone_$2_REJECT 1 -o $1 -j reject
        $IPTABLES -I zone_$2_ACCEPT 1 -i $1 -j ACCEPT
        $IPTABLES -I zone_$2_DROP 1 -i $1 -j DROP
-       $IPTABLES -I zone_$2_REJECT 1 -i $1 -j REJECT
+       $IPTABLES -I zone_$2_REJECT 1 -i $1 -j reject
        $IPTABLES -I zone_$2_nat 1 -t nat -o $1 -j MASQUERADE 
        $IPTABLES -I PREROUTING 1 -t nat -i $1 -j zone_$2_prerouting 
-       $IPTABLES -A FORWARD -i $1 -j zone_$2_forward
+       $IPTABLES -A forward -i $1 -j zone_$2_forward
        uci_set_state firewall core "$2" "$1"
 }
 
 delif() {
        logger "removing $1 from firewall zone $2"
-       $IPTABLES -D INPUT -i $1 -j zone_$2
+       $IPTABLES -D input -i $1 -j zone_$2
        $IPTABLES -D zone_$2_ACCEPT -o $1 -j ACCEPT
        $IPTABLES -D zone_$2_DROP -o $1 -j DROP
-       $IPTABLES -D zone_$2_REJECT -o $1 -j REJECT
+       $IPTABLES -D zone_$2_REJECT -o $1 -j reject
        $IPTABLES -D zone_$2_ACCEPT -i $1 -j ACCEPT
        $IPTABLES -D zone_$2_DROP -i $1 -j DROP
-       $IPTABLES -D zone_$2_REJECT -i $1 -j REJECT
+       $IPTABLES -D zone_$2_REJECT -i $1 -j reject
        $IPTABLES -D zone_$2_nat -t nat -o $1 -j MASQUERADE 
        $IPTABLES -D PREROUTING -t nat -i $1 -j zone_$2_prerouting 
-       $IPTABLES -D FORWARD -i $1 -j zone_$2_forward
+       $IPTABLES -D forward -i $1 -j zone_$2_forward
        uci_revert_state firewall core "$2"
 }
 
 load_synflood() {
+       local rate=${1:-25}
+       local burst=${2:-50}
        echo "Loading synflood protection"
-       $IPTABLES -N SYN_FLOOD
-       $IPTABLES -A SYN_FLOOD -p tcp --syn -m limit --limit ${1}/second --limit-burst $2 -j RETURN
-       $IPTABLES -A SYN_FLOOD -p ! tcp -j RETURN
-       $IPTABLES -A SYN_FLOOD -p tcp ! --syn -j RETURN
-       $IPTABLES -A SYN_FLOOD -j LOG --log-prefix "syn_flood: " 
-       $IPTABLES -A SYN_FLOOD -j DROP
-       $IPTABLES -A INPUT -p tcp --syn -j SYN_FLOOD
+       $IPTABLES -N syn_flood
+       $IPTABLES -A syn_flood -p tcp --syn -m limit --limit $rate/second --limit-burst $burst -j RETURN
+       $IPTABLES -A syn_flood -j DROP
+       $IPTABLES -A INPUT -p tcp --syn -j syn_flood
+}
+
+fw_set_chain_policy() {
+       local chain=$1
+       local target=$2
+       [ "$target" == "REJECT" ] && {
+               $IPTABLES -A $chain -j reject
+               target=DROP
+       }
+       $IPTABLES -P $chain $target
 }
 
 fw_defaults() {
@@ -116,21 +125,23 @@ fw_defaults() {
        uci_revert_state firewall core
        uci_set_state firewall core "" firewall_state 
 
+       $IPTABLES -P INPUT DROP
+       $IPTABLES -P OUTPUT DROP
+       $IPTABLES -P FORWARD DROP
+
        $IPTABLES -F
-       $IPTABLES -t nat -F
        $IPTABLES -t mangle -F
-       $IPTABLES -X -t nat
+       $IPTABLES -t nat -F
+       $IPTABLES -t mangle -X
+       $IPTABLES -t nat -X
        $IPTABLES -X
        
-       $IPTABLES -P INPUT $input
        $IPTABLES -A INPUT -m state --state INVALID -j DROP
        $IPTABLES -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
                
-       $IPTABLES -P OUTPUT $output
        $IPTABLES -A OUTPUT -m state --state INVALID -j DROP
        $IPTABLES -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
        
-       $IPTABLES -P FORWARD $forward
        $IPTABLES -A FORWARD -m state --state INVALID -j DROP
        $IPTABLES -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
        $IPTABLES -A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT
@@ -141,10 +152,19 @@ fw_defaults() {
        config_get syn_flood $1 syn_flood
        config_get syn_rate $1 syn_rate
        config_get syn_burst $1 syn_burst
-
-       [ -z "$syn_rate" ] && syn_rate=25
-       [ -z "$syn_burst" ] && syn_burst=50
        [ "$syn_flood" == "1" ] && load_synflood $syn_rate $syn_burst
+
+       $IPTABLES -N input
+       $IPTABLES -N output
+       $IPTABLES -N forward
+
+       $IPTABLES -A INPUT -j input
+       $IPTABLES -A OUTPUT -j output
+       $IPTABLES -A FORWARD -j forward
+
+       $IPTABLES -N reject
+       $IPTABLES -A reject -p tcp -j REJECT --reject-with tcp-reset
+       $IPTABLES -A reject -j REJECT --reject-with icmp-port-unreachable
 }
 
 fw_zone() {
@@ -186,7 +206,7 @@ fw_rule() {
        config_get ruleset $1 ruleset
 
        [ -z "$target" ] && target=DROP
-       [ -n "$src" ] && ZONE=zone_$src || ZONE=INPUT
+       [ -n "$src" ] && ZONE=zone_$src || ZONE=input
        [ -n "$dest" ] && TARGET=zone_${dest}_$target || TARGET=$target
        add_rule() {
                $IPTABLES -I $ZONE 1 \
@@ -215,7 +235,7 @@ fw_forwarding() {
 
        config_get src $1 src
        config_get dest $1 dest
-       [ -n "$src" ] && z_src=zone_${src}_forward || z_src=FORWARD
+       [ -n "$src" ] && z_src=zone_${src}_forward || z_src=forward
        [ -n "$dest" ] && z_dest=zone_${dest}_ACCEPT || z_dest=ACCEPT
        $IPTABLES -I $z_src 1 -j $z_dest
 }
@@ -339,13 +359,17 @@ fw_init() {
        unset CONFIG_APPEND
        config_load network
        config_foreach fw_addif interface
+       fw_set_chain_policy INPUT $input
+       fw_set_chain_policy OUTPUT $output
+       fw_set_chain_policy FORWARD $forward
 }
 
 fw_stop() {
        $IPTABLES -F
-       $IPTABLES -t nat -F
        $IPTABLES -t mangle -F
-       $IPTABLES -X -t nat
+       $IPTABLES -t nat -F
+       $IPTABLES -t mangle -X
+       $IPTABLES -t nat -X
        $IPTABLES -X
        $IPTABLES -P INPUT ACCEPT
        $IPTABLES -P OUTPUT ACCEPT