xref: /src/external/bsd/blocklist/libexec/blocklistd-helper

#!/bin/sh
#echo "run $@" 1>&2
#set -x
# $1 command
# $2 rulename
# $3 protocol
# $4 address
# $5 mask
# $6 port
# $7 id

pf=
if [ -f "/etc/ipfw-blocklist.rc" ]; then
	pf="ipfw"
	. /etc/ipfw-blocklist.rc
	ipfw_offset=${ipfw_offset:-2000}
fi

if [ -z "$pf" ]; then
	for f in npf pf ipfilter ipfw; do
		if [ -x /etc/rc.d/$f ]; then
			if /etc/rc.d/$f status >/dev/null 2>&1; then
				pf="$f"
				break
			fi
		elif [ -f "/etc/$f.conf" ]; then
			# xxx assume a config file means it can be enabled --
			# and the first one wins!
			pf="$f"
			break
		fi
	done
fi

if [ -z "$pf" -a -x "/sbin/iptables" ]; then
	pf="iptables"
fi

if [ -z "$pf" ]; then
	echo "$0: Unsupported packet filter" 1>&2
	exit 1
fi

flags=
if [ -n "$3" ]; then
	raw_proto="$3"
	proto="proto $3"
	if [ $3 = "tcp" ]; then
		flags="flags S/SAFR"
	fi
fi

if [ -n "$6" ]; then
	raw_port="$6"
	port="port $6"
fi

addr="$4"
mask="$5"
case "$4" in
::ffff:*.*.*.*)
	if [ "$5" = 128 ]; then
		mask=32
		addr=${4#::ffff:}
	fi;;
esac

case "$1" in
add)
	case "$pf" in
	ipfilter)
		# N.B.:  If you reload /etc/ipf.conf then you need to stop and
		# restart blocklistd (and make sure blocklistd_flags="-r").
		# This should normally already be implemented in
		# /etc/rc.d/ipfilter, but if then not add the following lines to
		# the end of the ipfilter_reload() function:
		#
		#	if checkyesnox blocklistd; then
		#		/etc/rc.d/blocklistd restart
		#	fi
		#
		# XXX we assume the following rule is present in /etc/ipf.conf:
		# (should we check? -- it probably cannot be added dynamically)
		#
		#	block in proto tcp/udp from any to any head blocklistd
		#
		# where "blocklistd" is the default rulename (i.e. "$2")
		#
		# This rule can come before any rule that logs connections,
		# etc., and should be followed by final rules such as:
		#
		#	# log all as-yet unblocked incoming TCP connection
		#	# attempts
		#	log in proto tcp from any to any flags S/SAFR
		#	# last "pass" match wins for all non-blocked packets
		#	pass in all
		#	pass out all
		#
		# I.e. a "pass" rule which will be the final match and override
		# the "block".  This way the rules added by blocklistd will
		# actually block packets, and prevent logging of them as
		# connections, because they include the "quick" flag.
		#
		# N.b.:  $port is not included/used in rules -- abusers are cut
		# off completely from all services!
		#
		# Note RST packets are not returned for blocked SYN packets of
		# active attacks, so the port will not appear to be closed.
		# This will probably give away the fact that a firewall has been
		# triggered to block connections, but it prevents generating
		# extra outbound traffic, and it may also slow down the attacker
		# somewhat.
		#
		# Note also that we don't block all packets, just new attempts
		# to open connections (see $flags above).  This allows us to do
		# counterespionage against the attacker (or continue to make use
		# of any other services that might be on the same subnet as the
		# supposed attacker).  However it does not kill any active
		# connections -- we rely on the reporting daemon to do its own
		# protection and cleanup.
		#
		# N.B.:  The rule generated here must exactly match the
		# corresponding rule generated for the "rem" command below!
		#
		echo block in log quick $proto \
		    from $addr/$mask to any $flags group $2 | \
		    /sbin/ipf -A -f - >/dev/null 2>&1 && echo OK
		;;

	ipfw)
		# use $ipfw_offset+$port for rule number
		rule=$(($ipfw_offset + $6))
		tname="port$6"
		/sbin/ipfw table $tname create type addr 2>/dev/null
		/sbin/ipfw -q table $tname add "$addr/$mask"
		# if rule number $rule does not already exist, create it
		/sbin/ipfw show $rule >/dev/null 2>&1 || \
			/sbin/ipfw add $rule drop $3 from \
			table"("$tname")" to any dst-port $6 >/dev/null && \
			echo OK
		;;

	iptables)
		if ! /sbin/iptables --list "$2" >/dev/null 2>&1; then
			/sbin/iptables --new-chain "$2"
		fi
		/sbin/iptables --append INPUT --proto "$raw_proto" \
		    --dport "$raw_port" --jump "$2"
		/sbin/iptables --append "$2" --proto "$raw_proto" \
		    --source "$addr/$mask" --dport "$raw_port" --jump DROP
		echo OK
		;;

	npf)
		/sbin/npfctl rule "$2" add block in final $proto from \
		    "$addr/$mask" to any $port
		;;

	pf)
		# if the filtering rule does not exist, create it
		/sbin/pfctl -a "$2/$6" -sr 2>/dev/null | \
		    grep -q "<port$6>" || \
		    echo "block in quick $proto from <port$6> to any $port" | \
		    /sbin/pfctl -a "$2/$6" -f -
		# insert $ip/$mask into per-protocol/port anchored table
		/sbin/pfctl -qa "$2/$6" -t "port$6" -T add "$addr/$mask" && \
		    /sbin/pfctl -qk "$addr" && echo OK
		;;

	esac
	;;
rem)
	case "$pf" in
	ipfilter)
		# N.B.:  The rule generated here must exactly match the
		# corresponding rule generated for the "add" command above!
		#
		echo block in log quick $proto \
		    from $addr/$mask to any $flags group $2 | \
		    /sbin/ipf -A -r -f - >/dev/null 2>&1 && echo OK
		;;

	ipfw)
		/sbin/ipfw table "port$6" delete "$addr/$mask" 2>/dev/null && \
		    echo OK
		;;

	iptables)
		if /sbin/iptables --list "$2" >/dev/null 2>&1; then
			/sbin/iptables --delete "$2" --proto "$raw_proto" \
			    --source "$addr/$mask" --dport "$raw_port" \
			    --jump DROP
		fi
		echo OK
		;;

	npf)
		/sbin/npfctl rule "$2" rem-id "$7"
		;;

	pf)
		/sbin/pfctl -qa "$2/$6" -t "port$6" -T delete "$addr/$mask" && \
		    echo OK
		;;

	esac
	;;
flush)
	case "$pf" in
	ipfilter)
		#
		# N.B. WARNING:  This is obviously not reentrant!
		#
		# First we flush all the rules from the inactive set, then we
		# reload the ones that do not belong to the group "$2", and
		# finally we swap the active and inactive rule sets.
		#
		/sbin/ipf -I -F a
		#
		# "ipf -I -F a" also flushes active accounting rules!
		#
		# Note that accounting rule groups are unique to accounting
		# rules and have nothing to do with filter rules, though of
		# course theoretically one could use the same group name for
		# them too.
		#
		# In theory anyone using any such accounting rules should have a
		# wrapper /etc/rc.conf.d/blocklistd script (and corresponding
		# /etc/rc.conf.d/ipfilter script) that will record and
		# consolidate the values accumulated by such accounting rules
		# before they are flushed, since otherwise their counts will be
		# lost forever.
		#
		/usr/sbin/ipfstat -io | fgrep -v "group $2" | \
		    /sbin/ipf -I -f - >/dev/null 2>&1
		#
		# This MUST be done last and separately as "-s" is executed
		# _while_ the command arguments are being processed!
		#
		/sbin/ipf -s && echo OK
		;;

	ipfw)
		/sbin/ipfw table "port$6" flush 2>/dev/null && echo OK
		;;

	iptables)
		if /sbin/iptables --list "$2" >/dev/null 2>&1; then
			/sbin/iptables --flush "$2"
		fi
		echo OK
		;;

	npf)
		/sbin/npfctl rule "$2" flush
		;;

	pf)
		# dynamically determine which anchors exist
		for anchor in $(/sbin/pfctl -a "$2" -s Anchors 2> /dev/null); do
			/sbin/pfctl -a "$anchor" -t "port${anchor##*/}" -T flush
			/sbin/pfctl -a "$anchor" -F rules
		done
		echo OK
		;;
	esac
	;;
*)
	echo "$0: Unknown command '$1'" 1>&2
	exit 1
	;;
esac