## Ensure that the named chains exist and are empty.
clearchain () {
set -e
- for chain; do
- case $chain in
- *:*) table=${chain%:*} chain=${chain#*:} ;;
+ for _chain; do
+ case $_chain in
+ *:*) table=${_chain%:*} _chain=${_chain#*:} ;;
*) table=filter ;;
esac
- run ip46tables -t $table -N $chain 2>/dev/null || :
+ run ip46tables -t $table -N $_chain 2>/dev/null || :
done
}
makeset () {
set -e
name=$1; shift
- if ipset -nL | grep -q "^Name: $name$"; then
- :
- else
- ipset -N "$name" "$@"
- fi
+ v=$(ipset --version)
+ createp=t
+ case "$v" in
+ "ipset v4"*)
+ if ipset -nL | grep -q "^Name: $name\$"; then createp=nil; fi
+ ;;
+ *)
+ if ipset -n -L | grep -q "^$name\$"; then createp=nil; fi
+ ;;
+ esac
+ case $createp in
+ t) ipset -N "$name" "$@" ;;
+ esac
}
## errorchain CHAIN ACTION ARGS ...
clearchain $table:$chain
run ip46tables -t $table -A $chain -j LOG \
-m limit --limit 3/minute --limit-burst 10 \
- --log-prefix "fw: $chain " --log-level notice
+ --log-prefix "fw: $chain " --log-level notice || :
run ip46tables -t $table -A $chain -j "$@" \
-m limit --limit 20/second --limit-burst 100
run ip46tables -t $table -A $chain -j DROP
for ver in ipv4 ipv6; do
if [ -f /proc/sys/net/$ver/conf/$i/$opt ]; then
any=t
- run sysctl -q net/ipv4/conf/$i/$opt="$val"
+ run sysctl -q net/$ver/conf/$i/$opt="$val"
fi
done
case $any in
run ip6tables -N accept-non-init-frag
run ip6tables -A accept-non-init-frag -j RETURN \
-m frag --fragfirst
-run ip6tables -A accept-non-init-frag -j ACCEPT
+run ip6tables -A accept-non-init-frag -j ACCEPT \
+ -m ipv6header --header frag
m4_divert(20)m4_dnl
## allowservices CHAIN PROTO SERVICE ...
ntpchain=$1; shift
clearchain ntp-servers
- for ntp; do run iptables -A ntp-servers -j ACCEPT -s $ntp; done
- run iptables -A $ntpchain -j ntp-servers \
+ for ntp; do
+ case $ntp in *:*) ipt=ip6tables ;; *) ipt=iptables ;; esac
+ run $ipt -A ntp-servers -j ACCEPT -s $ntp;
+ done
+ run ip46tables -A $ntpchain -j ntp-servers \
-p udp --source-port 123 --destination-port 123
}
done
}
+## dnsserver CHAIN
+##
+## Add rules to allow CHAIN to be a DNS server.
+dnsserver () {
+ set -e
+ chain=$1
+
+ ## Allow TCP access. Hitting us with SYNs will make us deploy SYN cookies,
+ ## but that's tolerable.
+ run ip46tables -A $chain -j ACCEPT -p tcp --destination-port 53
+
+ ## Avoid being a DDoS amplifier by rate-limiting incoming DNS queries.
+ clearchain $chain-udp-dns
+ run ip46tables -A $chain-udp-dns -j ACCEPT \
+ -m limit --limit 20/second --limit-burst 300
+ run ip46tables -A $chain-udp-dns -g dns-rate-limit
+ run ip46tables -A $chain -j $chain-udp-dns \
+ -p udp --destination-port 53
+}
+
## openports CHAIN [MIN MAX]
##
## Add rules to CHAIN to allow the open ports.
run ip46tables -A $chain -p udp -g interesting --destination-port $1:$2
}
+bcp38_setup=:
+bcp38 () {
+ ipv=$1 ifname=$2; shift 2
+ ## Add rules for BCP38 egress filtering for IP version IPV (either 4 or 6).
+ ## IFNAME is the outgoing interface; the remaining arguments are network
+ ## prefixes.
+
+ ## Sort out which command we're using
+ case $ipv in
+ 4) ipt=iptables ;;
+ 6) ipt=ip6tables ;;
+ *) echo >&2 "Unknown IP version $ipv"; exit 1 ;;
+ esac
+
+ ## If we've not set up the error chain then do that.
+ case $bcp38_setup in
+ :)
+ errorchain bcp38 DROP
+ clearchain bcp38-check
+ ip46tables -A bcp38-check -g bcp38
+ ;;
+ esac
+
+ ## Stitch our egress filter into the outbound chains if we haven't done
+ ## that yet. Do this for both IP versions: if we're only ever given
+ ## IPv6 addresses for a particular interface then we assume that IPv4
+ ## packets aren't allowed on it at all.
+ case $bcp38_setup in
+ *:$ifname:*) ;;
+ *)
+ run ip46tables -A OUTPUT -j bcp38-check -o $ifname
+ case $forward in
+ 1) run ip46tables -A FORWARD -j bcp38-check -o $ifname ;;
+ esac
+ bcp38_setup=$bcp38_setup$ifname:
+ ;;
+ esac
+
+ ## Finally, add in our allowed networks.
+ for i in "$@"; do
+ run $ipt -I bcp38-check -j RETURN -s $i
+ done
+}
+
m4_divert(20)m4_dnl
###--------------------------------------------------------------------------
### Packet classification.
### `defnetclass'.
### net_inet_NET List of IPv4 address ranges in the network.
### net_inet6_NET List of IPv6 address ranges in the network.
-### net_fwd_NET List of other networks that this one forwards to.
+### net_via_NET List of other networks that this one forwards via.
### net_hosts_NET List of hosts known to be in the network.
### host_inet_HOST IPv4 address of the named HOST.
### host_inet6_HOST IPv6 address of the named HOST.
trace "netclass $name = $netclassindex"
eval from_$name=$(( $netclassindex << $BIT_FROM ))
eval to_$name=$(( $netclassindex << $BIT_TO ))
- eval _mask_$name=$(( 1 << ($netclassindex + $BIT_MASK) ))
+ eval fwd_$name=$(( 1 << ($netclassindex + $BIT_MASK) ))
nets="$nets $name"
;;
2)
- ## Pass 2. Compute the actual from and to values. We're a little bit
- ## clever during source classification, and set the TO field to
- ## all-bits-one, so that destination classification needs only a single
- ## AND operation.
- from=$(( ($netclassindex << $BIT_FROM) + (0xf << $BIT_TO) ))
+ ## Pass 2. Compute the actual from and to values. This is fiddly:
+ ## we want to preserve the other flags.
+ from=$(( ($netclassindex << $BIT_FROM) ))
+ frommask=$(( $MASK_FROM | $MASK_MASK ))
for net; do
- eval bit=\$_mask_$net
+ eval bit=\$fwd_$net
from=$(( $from + $bit ))
done
- to=$(( ($netclassindex << $BIT_TO) + \
- (0xf << $BIT_FROM) + \
- (1 << ($netclassindex + $BIT_MASK)) ))
- trace "from $name --> set $(printf %x $from)"
- trace " to $name --> and $(printf %x $from)"
+ to=$(( ($netclassindex << $BIT_TO) ))
+ tomask=$(( $MASK_TO | $MASK_MASK ^ (1 << ($netclassindex + $BIT_MASK)) ))
+ trace "from $name --> set $(printf %08x/%08x $from $frommask)"
+ trace " to $name --> set $(printf %08x/%08x $to $tomask)"
## Now establish the mark-from-NAME and mark-to-NAME chains.
clearchain mangle:mark-from-$name mangle:mark-to-$name
- run ip46tables -t mangle -A mark-from-$name -j MARK --set-mark $from
- run ip46tables -t mangle -A mark-to-$name -j MARK --and-mark $to
+ run ip46tables -t mangle -A mark-from-$name -j MARK \
+ --set-xmark $from/$frommask
+ run ip46tables -t mangle -A mark-to-$name -j MARK \
+ --set-xmark $to/$tomask
;;
esac
netclassindex=$(( $netclassindex + 1 ))
## defnet NET CLASS
##
-## Define a network. Follow by calls to `addr', `forwards', etc. to define
+## Define a network. Follow by calls to `addr', `via', etc. to define
## properties of the network. Networks are processed in order, so if their
## addresses overlap then the more specific addresses should be defined
## earlier.
done
}
-## forwards NET ...
+## via NET ...
##
## Declare that packets from this network are forwarded to the other NETs.
-forwards () {
- eval "net_fwd_$net=\"$*\""
+via () {
+ eval "net_via_$net=\"$*\""
}
## noxit NET ...
for n in $nn; do
addr=${n%/*}
base=${addr%::*}
- case $a in ::*) aa=$addr$a ;; *) aa=$a ;; esac
+ case $a6 in ::*) aa=$base$a6 ;; *) aa=$a6 ;; esac
eval host_inet6_$name=$aa
done
defhost () {
host=$1
addword allhosts $host
- eval host_type_$host=endsys
+ eval host_type_$host=server
}
-## router
+## hosttype TYPE
##
-## Declare the host to be a router, so it should forward packets and so on.
-router () {
- eval host_type_$host=router
+## Declare the host to have the given type.
+hosttype () {
+ type=$1
+ case $type in
+ router | server | client) ;;
+ *) echo >&2 "$0: bad host type \`$type'"; exit 1 ;;
+ esac
+ eval host_type_$host=$type
}
## iface IFACE NET ...
done
}
+## matchnets OPT WIN FLAGS PREPARE BASE SUFFIX NEXT NET [NET ...]
+##
+## Build rules which match a particular collection of networks.
+##
+## Specifically, use the address-comparison operator OPT (typically `-s' or
+## `-d') to match the addresses of each NET, writing the rules to the chain
+## BASESUFFIX. If we find a match, dispatch to WIN-CLASS, where CLASS is the
+## class of the matching network. In order to deal with networks containing
+## negative address ranges, more chains may need to be constructed; they will
+## be named BASE#Q for sequence numbers Q starting with NEXT. All of this
+## happens on the `mangle' table, and there isn't (currently) a way to tweak
+## this.
+##
+## The FLAGS gather additional interesting information about the job,
+## separated by colons. The only flag currently is :default: which means
+## that the default network was listed.
+##
+## Finally, there is a hook PREPARE which is called just in advance of
+## processing the final network, passing it the argument FLAGS. (The PREPARE
+## string will be subjected to shell word-splitting, so it can provide some
+## arguments of its own if it wants.) It should set `mode' to indicate how
+## the chain should be finished.
+##
+## goto If no networks matched, then issue a final `goto' to the
+## chain named by the variable `fail'.
+##
+## call Run `$finish CHAIN' to write final rules to the named CHAIN
+## (which may be suffixed from the original BASE argument if
+## this was necessary). This function will arrange to call
+## these rules if no networks match.
+##
+## ret If no network matches then return (maybe by falling off the
+## end of the chain).
+matchnets () {
+ local opt win flags prepare base suffix next net lose splitp
+ opt=$1 win=$2 flags=$3 prepare=$4 base=$5 suffix=$6 next=$7 net=$8
+ shift 8
+
+ ## If this is the default network, then set the flag.
+ case "$net" in default) flags=${flags}default: ;; esac
+
+ ## Do an initial pass over the addresses to see whether there are any
+ ## negative ranges. If so, we'll need to split. See also the standard
+ ## joke about soup.
+ splitp=nil
+ eval "addrs=\"\$net_inet_$net \$net_inet6_$net\""
+ for a in $addrs; do case $a in !*) splitp=t; break ;; esac; done
+
+ trace "MATCHNETS [splitp $splitp] $opt $win $flags [$prepare] $base $suffix $next : $net $*"
+
+ ## Work out how to handle matches against negative address ranges. If this
+ ## is the last network, invoke the PREPARE hook to find out. Otherwise, if
+ ## we have to split the chain, recursively build the target here.
+ case $splitp,$# in
+ t,0 | nil,0)
+ $prepare $flags
+ case $splitp,$mode in
+ *,goto)
+ lose="-g $fail"
+ ;;
+ *,ret)
+ lose="-j RETURN"
+ ;;
+ t,call)
+ clearchain mangle:$base#$next
+ lose="-g $base#$next"
+ ;;
+ nil,call)
+ ;;
+ esac
+ ;;
+ t,*)
+ clearchain mangle:$base#$next
+ matchnets $opt $win $flags "$prepare" \
+ $base \#$next $(( $next + 1 )) "$@"
+ lose="-g $base#$next" mode=goto
+ ;;
+ *)
+ mode=continue
+ ;;
+ esac
+
+ ## Populate the chain with rules to match the necessary networks.
+ eval addr=\$net_inet_$net addr6=\$net_inet6_$net class=\$net_class_$net
+ for a in $addr; do
+ case $a in
+ !*) run iptables -t mangle -A $base$suffix $lose $opt ${a#!} ;;
+ *) run iptables -t mangle -A $base$suffix -g $win-$class $opt $a ;;
+ esac
+ done
+ for a in $addr6; do
+ case $a in
+ !*) run ip6tables -t mangle -A $base$suffix $lose $opt ${a#!} ;;
+ *) run ip6tables -t mangle -A $base$suffix -g $win-$class $opt $a ;;
+ esac
+ done
+
+ ## Wrap up the chain appropriately. If we didn't split and there are more
+ ## networks to handle then append the necessary rules now. (If we did
+ ## split, then we already wrote the rules for them above.) If there are no
+ ## more networks then consult the `mode' setting to find out what to do.
+ case $splitp,$#,$mode in
+ *,0,ret) ;;
+ *,*,goto) run ip46tables -t mangle -A $base$suffix $lose ;;
+ t,0,call) $finish $base#$next ;;
+ nil,0,call) $finish $base$suffix ;;
+ nil,*,*)
+ matchnets $opt $win $flags "$prepare" $base "$suffix" $next "$@"
+ ;;
+ esac
+}
+
## net_interfaces HOST NET
##
## Determine the interfaces on which packets may plausibly arrive from the
nextnets=""
any=nil
for net in $nets; do
- eval fwd=\$net_fwd_$net
- for n in $fwd; do
+ eval via=\$net_via_$net
+ for n in $via; do
case $seen in *":$n:"*) continue ;; esac
seen=$seen$n:
eval noxit=\$net_noxit_$n
~mdw / firewall / blobdiff