shorewall_code/Shorewall/lib.core

#
# Shorewall 4.5 -- /usr/share/shorewall/lib.core.
#
#     This program is under GPL [http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt]
#
#     (c) 2010-2012 - Tom Eastep (teastep@shorewall.net)
#
#	Complete documentation is available at http://shorewall.net
#
#	This program is free software; you can redistribute it and/or modify
#	it under the terms of Version 2 of the GNU General Public License
#	as published by the Free Software Foundation.
#
#	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, write to the Free Software
#	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
# The purpose of this library is to hold those functions used by the generated
# scripts (both IPv4 and IPv6 -- the functions that are specific to one or the other
# are found in prog.header and prog.header6).
#
#########################################################################################
#
# Conditionally produce message
#
progress_message() # $* = Message
{
    local timestamp
    timestamp=

    if [ $VERBOSITY -gt 1 ]; then
	[ -n "$g_timestamp" ] && timestamp="$(date +%H:%M:%S) "
	echo "${timestamp}$@"
    fi

    if [ $LOG_VERBOSITY -gt 1 ]; then
        timestamp="$(date +'%b %_d %T') "
        echo "${timestamp}$@" >> $STARTUP_LOG
    fi
}

progress_message2() # $* = Message
{
    local timestamp
    timestamp=

    if [ $VERBOSITY -gt 0 ]; then
	[ -n "$g_timestamp" ] && timestamp="$(date +%H:%M:%S) "
	echo "${timestamp}$@"
    fi

    if [ $LOG_VERBOSITY -gt 0 ]; then
        timestamp="$(date +'%b %_d %T') "
        echo "${timestamp}$@" >> $STARTUP_LOG
    fi
}

progress_message3() # $* = Message
{
    local timestamp
    timestamp=

    if [ $VERBOSITY -ge 0 ]; then
	[ -n "$g_timestamp" ] && timestamp="$(date +%H:%M:%S) "
	echo "${timestamp}$@"
    fi

    if [ $LOG_VERBOSITY -ge 0 ]; then
        timestamp="$(date +'%b %_d %T') "
        echo "${timestamp}$@" >> $STARTUP_LOG
    fi
}

#
# Set a standard chain's policy
#
setpolicy() # $1 = name of chain, $2 = policy
{
    run_iptables -P $1 $2
}

#
# Generate a list of all network interfaces on the system
#
find_all_interfaces() {
    ${IP:-ip} link list | egrep '^[[:digit:]]+:' | cut -d ' ' -f2 | sed -r 's/(@.*)?:$//'
}

#
# Generate a list of all network interfaces on the system that have an ipvX address
#
find_all_interfaces1() {
    ${IP:-ip} -$g_family addr list | egrep '^[[:digit:]]+:' | cut -d ' ' -f2 | sed -r 's/(@.*)?:$//'
}

#
# Find the value 'dev' in the passed arguments then echo the next value
#

find_device() {
    while [ $# -gt 1 ]; do
	[ "x$1" = xdev ] && echo $2 && return
	shift
    done
}

#
# Find the value 'via' in the passed arguments then echo the next value
#

find_gateway() {
    while [ $# -gt 1 ]; do
	[ "x$1" = xvia ] && echo $2 && return
	shift
    done
}

#
# Find the value 'mtu' in the passed arguments then echo the next value
#

find_mtu() {
    while [ $# -gt 1 ]; do
	[ "x$1" = xmtu ] && echo $2 && return
	shift
    done
}

#
# Find the value 'peer' in the passed arguments then echo the next value up to
# "/"
#

find_peer() {
    while [ $# -gt 1 ]; do
	[ "x$1" = xpeer ] && echo ${2%/*} && return
	shift
    done
}

#
# Try to find the gateway through an interface looking for 'nexthop'

find_nexthop() # $1 = interface
{
    echo $(find_gateway `$IP -$g_family route list | grep "[[:space:]]nexthop.* $1"`)
}

#
# Find the default route's interface
#
find_default_interface() {
    $IP -$g_family route list | while read first rest; do
	[ "$first" = default ] && echo $(find_device $rest) && return
    done
}

#
# Determine if Interface is up
#
interface_is_up() {
    [ -n "$($IP -$g_family link list dev $1 2> /dev/null | grep -e '[<,]UP[,>]')" ]
}

#
# Determine if interface is usable from a Netfilter perspective
#
interface_is_usable() # $1 = interface
{
    [ "$1" = lo ] && return 0
    interface_is_up $1 && [ "$(find_first_interface_address_if_any $1)" != :: ] && run_isusable_exit $1
}

#
# Find interface addresses--returns the set of addresses assigned to the passed
# device
#
find_interface_addresses() # $1 = interface
{
    if [ $g_family -eq 4 ]; then
	$IP -f inet addr show $1 2> /dev/null | grep inet\  | sed 's/\s*inet //;s/\/.*//;s/ peer.*//'
    else
	$IP -f inet6 addr show $1 2> /dev/null | grep 'inet6 2' | sed 's/\s*inet6 //;s/\/.*//;s/ peer.*//'
    fi
}

#
#  echo the list of networks routed out of a given interface
#
get_routed_networks() # $1 = interface name, $2-n = Fatal error message
{
    local address
    local rest

    $IP -$g_family route show dev $1 2> /dev/null |
	while read address rest; do
	    case "$address" in
		default)
		    if [ $# -gt 1 ]; then
			shift
			fatal_error "$@"
		    else
			echo "WARNING: default route ignored on interface $1" >&2
		    fi
		    ;;
		multicast|broadcast|prohibit|nat|throw|nexthop)
		    ;;
		[2-3]*)
		    [ "$address" = "${address%/*}" ] && address="${address}/128"
		    echo $address
		    ;;
		*)
		    if [ $g_family -eq 4 ]; then
			[ "$address" = "${address%/*}" ] && address="${address}/128"
			echo $address
		    fi
		    ;;
	    esac
        done
}

#
# Clear the current traffic shaping configuration
#

delete_tc1()
{
    clear_one_tc() {
        $TC qdisc del dev $1 root 2> /dev/null
        $TC qdisc del dev $1 ingress 2> /dev/null

    }

    run_tcclear_exit

    run_ip link list | \
    while read inx interface details; do
        case $inx in
            [0-9]*)
                clear_one_tc ${interface%:}
                ;;
            *)
                ;;
        esac
    done
}

#
# Detect a device's MTU -- echos the passed device's MTU
#
get_device_mtu() # $1 = device
{
    local output
    output="$($IP link list dev $1 2> /dev/null)" # quotes required for /bin/ash

    if [ -n "$output" ]; then
	echo $(find_mtu $output)
    else
	echo 1500
    fi
}

#
# Version of the above that doesn't generate any output for MTU 1500.
# Generates 'mtu <mtu+>' otherwise, where <mtu+> is the device's MTU + 100
#
get_device_mtu1() # $1 = device
{
    local output
    output="$($IP link list dev $1 2> /dev/null)" # quotes required for /bin/ash
    local mtu

    if [ -n "$output" ]; then
	mtu=$(find_mtu $output)
	if [ -n "$mtu" ]; then
	    [ $mtu = 1500 ] || echo mtu $(($mtu + 100))
	fi
    fi

}

#
# Undo changes to routing
#
undo_routing() {
    local undofiles
    local f

    if [ -z "$g_noroutes"  ]; then
	#
	# Restore rt_tables database
	#
	if [ -f ${VARDIR}/rt_tables ]; then
	    [ -w /etc/iproute2/rt_table -a -z "$KEEP_RT_TABLES" ] && cp -f ${VARDIR}/rt_tables /etc/iproute2/ && progress_message "/etc/iproute2/rt_tables database restored"
	    rm -f ${VARDIR}/rt_tables
	fi
	#
	# Restore the rest of the routing table
	#
	undofiles="$(ls ${VARDIR}/undo_*routing 2> /dev/null)"

	if [ -n "$undofiles" ]; then
	    for f in $undofiles; do
		. $f
	    done

	    rm -f $undofiles

            progress_message "Shorewall-generated routing tables and routing rules removed"
	fi
    fi

}

#
# Save the default route
#
save_default_route() {
    awk \
    'BEGIN        {defroute=0;};
     /^default /  {defroute=1; print; next};
     /nexthop/    {if (defroute == 1 ) {print ; next} };
                  { defroute=0; };'
}

#
# Restore the default route that was in place before the initial 'shorewall start'
#
replace_default_route() # $1 = USE_DEFAULT_RT
{
    #
    # default_route and result are inherited from the caller
    #
    if [ -n "$default_route" ]; then
	case "$default_route" in
	    *metric*)
	        #
	        # Don't restore a default route with a metric unless USE_DEFAULT_RT=Yes. Otherwise, we only replace the one with metric 0
	        #
		[ -n "$1" ] && qt $IP -$g_family route replace $default_route && progress_message "Default Route (${default_route# }) restored"
		default_route=
		;;
	    *)
		qt $IP -$g_family route replace $default_route && progress_message "Default Route (${default_route# }) restored"
		result=0
		default_route=
		;;
	esac
    fi
}

restore_default_route() # $1 = USE_DEFAULT_RT
{
    local result
    result=1

    if [ -z "$g_noroutes" -a -f ${VARDIR}/default_route ]; then
	local default_route
	default_route=
	local route

	while read route ; do
	    case $route in
		default*)
		    replace_default_route $1
		    default_route="$default_route $route"
		    ;;
		*)
		    default_route="$default_route $route"
		    ;;
	    esac
	done < ${VARDIR}/default_route

	replace_default_route $1
	
	if [ $result = 1 ]; then
	    #
	    # We didn't restore a default route with metric 0
	    #
	    if $IP -$g_family -o route list 2> /dev/null | fgrep default | fgrep -qv metric; then
	       #
	       # But we added a default route with metric 0
	       #
	       qt $IP -$g_family route del default metric 0 && progress_message "Default route with metric 0 deleted"
	    fi
	fi

	rm -f ${VARDIR}/default_route
    fi

    return $result
}

#
# Flush the conntrack table if $g_purge is non-empty
#
conditionally_flush_conntrack() {

    if [ -n "$g_purge" ]; then
	if [ -n $(mywhich conntrack) ]; then
            conntrack -f ipv$g_family -F
	else
            error_message "WARNING: The '-p' option requires the conntrack utility which does not appear to be installed on this system"
	fi
    fi
}

#
# Issue a message and stop/restore the firewall.
#
fatal_error()
{
    echo "   ERROR: $@" >&2

    if [ $LOG_VERBOSITY -ge 0 ]; then
        timestamp="$(date +'%_b %d %T') "
        echo "${timestamp}  ERROR: $@" >> $STARTUP_LOG
    fi

    stop_firewall
    [ -n "$TEMPFILE" ] && rm -f $TEMPFILE
    exit 2
}

#
# Run iptables/ip6tables and if an error occurs, stop/restore the firewall
#
run_iptables()
{
    local status

    while [ 1 ]; do
	$g_tool $@
	status=$?
	[ $status -ne 4 ] && break
    done

    if [ $status -ne 0 ]; then
        error_message "ERROR: Command \"$g_tool $@\" Failed"
	stop_firewall
        exit 2
    fi
}

#
# Run iptables/ip6tables retrying exit status 4
#
do_iptables()
{
    local status

    while [ 1 ]; do
	$g_tool $@
	status=$?
	[ $status -ne 4 ] && return $status;
    done
}

#
# Run ip and if an error occurs, stop/restore the firewall
#
run_ip()
{
    if ! $IP -$g_family $@; then
	error_message "ERROR: Command \"$IP -$g_family $@\" Failed"
	stop_firewall
	exit 2
    fi
}

#
# Run tc and if an error occurs, stop/restore the firewall
#
run_tc() {
    if ! $TC $@ ; then
	error_message "ERROR: Command \"$TC $@\" Failed"
	stop_firewall
	exit 2
    fi
}

#
# Run the .iptables_restore_input as a set of discrete iptables commands
#
debug_restore_input() {
    local first second rest table chain
    #
    # Clear the ruleset
    #
    qt1 $g_tool -t mangle -F
    qt1 $g_tool -t mangle -X

    for chain in PREROUTING INPUT FORWARD POSTROUTING; do
	qt1 $g_tool -t mangle -P $chain ACCEPT
    done

    qt1 $g_tool -t raw    -F
    qt1 $g_tool -t raw    -X

    for chain in PREROUTING OUTPUT; do
	qt1 $g_tool -t raw -P $chain ACCEPT
    done

    qt1 $g_tool -t filter -F
    qt1 $g_tool -t filter -X

    for chain in INPUT FORWARD OUTPUT; do
	qt1 $g_tool -t filter -P $chain -P ACCEPT
    done

    while read first second rest; do
	case $first in
	    -*)
		#
		# We can't call run_iptables() here because the rules may contain quoted strings
		#
		eval $g_tool -t $table $first $second $rest

		if [ $? -ne 0 ]; then
		    error_message "ERROR: Command \"$g_tool $first $second $rest\" Failed"
		    stop_firewall
		    exit 2
		fi
		;;
	    :*)
		chain=${first#:}

		if [ "x$second" = x- ]; then
		    do_iptables -t $table -N $chain
		else
		    do_iptables -t $table -P $chain $second
		fi

		if [ $? -ne 0 ]; then
		    error_message "ERROR: Command \"$g_tool $first $second $rest\" Failed"
		    stop_firewall
		    exit 2
		fi
		;;
	    #
	    # This grotesque hack with the table names works around a bug/feature with ash
	    #
	    '*'raw)
		table=raw
		;;
	    '*'rawpost)
		table=rawpost
		;;
	    '*'mangle)
		table=mangle
		;;
	    '*'nat)
		table=nat
		;;
	    '*'filter)
		table=filter
		;;
	esac
    done
}