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775bd287 | 1 | ### -*-sh-*- |
bfdc045d MW |
2 | ### |
3 | ### Utility functions for firewall scripts | |
4 | ### | |
5 | ### (c) 2008 Mark Wooding | |
6 | ### | |
7 | ||
8 | ###----- Licensing notice --------------------------------------------------- | |
9 | ### | |
10 | ### This program is free software; you can redistribute it and/or modify | |
11 | ### it under the terms of the GNU General Public License as published by | |
12 | ### the Free Software Foundation; either version 2 of the License, or | |
13 | ### (at your option) any later version. | |
14 | ### | |
15 | ### This program is distributed in the hope that it will be useful, | |
16 | ### but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | ### GNU General Public License for more details. | |
19 | ### | |
20 | ### You should have received a copy of the GNU General Public License | |
21 | ### along with this program; if not, write to the Free Software Foundation, | |
22 | ### Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
23 | ||
24 | m4_divert(20)m4_dnl | |
25 | ###-------------------------------------------------------------------------- | |
26 | ### Utility functions. | |
27 | ||
28 | ## doit COMMAND ARGS... | |
29 | ## | |
30 | ## If debugging, print the COMMAND and ARGS. If serious, execute them. | |
31 | run () { | |
32 | set -e | |
33 | if [ "$FW_DEBUG" ]; then echo "* $*"; fi | |
34 | if ! [ "$FW_NOACT" ]; then "$@"; fi | |
35 | } | |
36 | ||
37 | ## trace MESSAGE... | |
38 | ## | |
39 | ## If debugging, print the MESSAGE. | |
40 | trace () { | |
41 | set -e | |
42 | if [ "$FW_DEBUG" ]; then echo "$*"; fi | |
43 | } | |
44 | ||
45 | ## defport NAME NUMBER | |
46 | ## | |
47 | ## Define $port_NAME to be NUMBER. | |
48 | defport () { | |
49 | name=$1 number=$2 | |
50 | eval port_$name=$number | |
51 | } | |
52 | ||
c70bfbbb MW |
53 | m4_divert(38)m4_dnl |
54 | ###-------------------------------------------------------------------------- | |
55 | ### Utility chains (used by function definitions). | |
56 | ||
bfdc045d MW |
57 | m4_divert(22)m4_dnl |
58 | ###-------------------------------------------------------------------------- | |
59 | ### Basic chain constructions. | |
60 | ||
0291d6d5 MW |
61 | ## ip46tables ARGS ... |
62 | ## | |
63 | ## Do the same thing for `iptables' and `ip6tables'. | |
64 | ip46tables () { | |
65 | set -e | |
66 | iptables "$@" | |
67 | ip6tables "$@" | |
68 | } | |
69 | ||
bfdc045d MW |
70 | ## clearchain CHAIN CHAIN ... |
71 | ## | |
72 | ## Ensure that the named chains exist and are empty. | |
73 | clearchain () { | |
74 | set -e | |
75 | for chain; do | |
76 | case $chain in | |
77 | *:*) table=${chain%:*} chain=${chain#*:} ;; | |
78 | *) table=filter ;; | |
79 | esac | |
0291d6d5 | 80 | run ip46tables -t $table -N $chain |
bfdc045d MW |
81 | done |
82 | } | |
83 | ||
84 | ## errorchain CHAIN ACTION ARGS ... | |
85 | ## | |
86 | ## Make a chain which logs a message and then invokes some other action, | |
87 | ## typically REJECT. Log messages are prefixed by `fw: CHAIN'. | |
88 | errorchain () { | |
89 | set -e | |
90 | chain=$1; shift | |
91 | case $chain in | |
92 | *:*) table=${chain%:*} chain=${chain#*:} ;; | |
93 | *) table=filter ;; | |
94 | esac | |
95 | clearchain $table:$chain | |
0291d6d5 | 96 | run ip46tables -t $table -A $chain -j LOG \ |
bfdc045d | 97 | -m limit --limit 3/minute --limit-burst 10 \ |
fc10e52b | 98 | --log-prefix "fw: $chain " --log-level notice |
0291d6d5 | 99 | run ip46tables -t $table -A $chain -j "$@" |
bfdc045d MW |
100 | } |
101 | ||
102 | m4_divert(24)m4_dnl | |
103 | ###-------------------------------------------------------------------------- | |
104 | ### Basic option setting. | |
105 | ||
106 | ## setopt OPTION VALUE | |
107 | ## | |
108 | ## Set an IP sysctl. | |
109 | setopt () { | |
110 | set -e | |
111 | opt=$1; shift; val=$* | |
112 | run sysctl -q net/ipv4/$opt="$val" | |
113 | } | |
114 | ||
115 | ## setdevopt OPTION VALUE | |
116 | ## | |
117 | ## Set an IP interface-level sysctl. | |
118 | setdevopt () { | |
119 | set -e | |
120 | opt=$1; shift; val=$* | |
121 | for i in /proc/sys/net/ipv4/conf/*; do | |
122 | [ -f $i/$opt ] && | |
123 | run sysctl -q net/ipv4/conf/${i#/proc/sys/net/ipv4/conf/}/$opt="$val" | |
124 | done | |
125 | } | |
126 | ||
127 | m4_divert(26)m4_dnl | |
128 | ###-------------------------------------------------------------------------- | |
129 | ### Packet filter construction. | |
130 | ||
131 | ## conntrack CHAIN | |
132 | ## | |
133 | ## Add connection tracking to CHAIN, and allow obvious stuff. | |
134 | conntrack () { | |
135 | set -e | |
136 | chain=$1 | |
0291d6d5 | 137 | run ip46tables -A $chain -p tcp -m state \ |
bfdc045d | 138 | --state ESTABLISHED,RELATED -j ACCEPT |
0291d6d5 | 139 | run ip46tables -A $chain -p tcp ! --syn -g bad-tcp |
bfdc045d MW |
140 | } |
141 | ||
ecdca131 MW |
142 | ## commonrules CHAIN |
143 | ## | |
144 | ## Add standard IP filtering rules to the CHAIN. | |
145 | commonrules () { | |
146 | set -e | |
147 | chain=$1 | |
148 | ||
149 | ## Pass fragments through, assuming that the eventual destination will sort | |
150 | ## things out properly. Except for TCP, that is, which should never be | |
c70bfbbb MW |
151 | ## fragmented. This is an extra pain for ip6tables, which doesn't provide |
152 | ## a pleasant way to detect non-initial fragments. | |
ecdca131 MW |
153 | run iptables -A $chain -p tcp -f -g tcp-fragment |
154 | run iptables -A $chain -f -j ACCEPT | |
0291d6d5 MW |
155 | run ip6tables -A $chain -p tcp -g tcp-fragment \ |
156 | -m ipv6header --soft --header frag | |
c70bfbbb | 157 | run ip6tables -A $chain -j accept-non-init-frag |
ecdca131 MW |
158 | } |
159 | ||
c70bfbbb MW |
160 | m4_divert(38)m4_dnl |
161 | ## Accept a non-initial fragment. This is only needed by IPv6, to work | |
162 | ## around a deficiency in the option parser. | |
163 | run ip6tables -N accept-non-init-frag | |
164 | run ip6tables -A accept-non-init-frag -j RETURN \ | |
165 | -m frag --fragfirst | |
166 | run ip6tables -A accept-non-init-frag -j ACCEPT | |
167 | ||
168 | m4_divert(26)m4_dnl | |
bfdc045d MW |
169 | ## allowservices CHAIN PROTO SERVICE ... |
170 | ## | |
171 | ## Add rules to allow the SERVICES on the CHAIN. | |
172 | allowservices () { | |
173 | set -e | |
174 | chain=$1 proto=$2; shift 2 | |
175 | count=0 | |
176 | list= | |
177 | for svc; do | |
178 | case $svc in | |
179 | *:*) | |
12ac65a1 | 180 | n=2 |
bfdc045d MW |
181 | left=${svc%:*} right=${svc#*:} |
182 | case $left in *[!0-9]*) eval left=\$port_$left ;; esac | |
183 | case $right in *[!0-9]*) eval right=\$port_$right ;; esac | |
184 | svc=$left:$right | |
185 | ;; | |
186 | *) | |
12ac65a1 | 187 | n=1 |
bfdc045d MW |
188 | case $svc in *[!0-9]*) eval svc=\$port_$svc ;; esac |
189 | ;; | |
190 | esac | |
191 | case $svc in | |
192 | *: | :* | "" | *[!0-9:]*) | |
12ac65a1 | 193 | echo >&2 "Bad service name" |
bfdc045d MW |
194 | exit 1 |
195 | ;; | |
196 | esac | |
197 | count=$(( $count + $n )) | |
198 | if [ $count -gt 15 ]; then | |
0291d6d5 | 199 | run ip46tables -A $chain -p $proto -m multiport -j ACCEPT \ |
bfdc045d MW |
200 | --destination-ports ${list#,} |
201 | list= count=$n | |
202 | fi | |
203 | list=$list,$svc | |
204 | done | |
205 | case $list in | |
206 | "") | |
207 | ;; | |
208 | ,*,*) | |
0291d6d5 | 209 | run ip46tables -A $chain -p $proto -m multiport -j ACCEPT \ |
bfdc045d MW |
210 | --destination-ports ${list#,} |
211 | ;; | |
12ac65a1 | 212 | *) |
0291d6d5 | 213 | run ip46tables -A $chain -p $proto -j ACCEPT \ |
bfdc045d MW |
214 | --destination-port ${list#,} |
215 | ;; | |
216 | esac | |
217 | } | |
218 | ||
219 | ## ntpclient CHAIN NTPSERVER ... | |
220 | ## | |
221 | ## Add rules to CHAIN to allow NTP with NTPSERVERs. | |
222 | ntpclient () { | |
223 | set -e | |
224 | chain=$1; shift | |
225 | for ntp; do | |
226 | run iptables -A $chain -s $ntp -j ACCEPT \ | |
227 | -p udp --source-port 123 --destination-port 123 | |
228 | done | |
229 | } | |
230 | ||
231 | ## dnsresolver CHAIN | |
232 | ## | |
233 | ## Add rules to allow CHAIN to be a DNS resolver. | |
234 | dnsresolver () { | |
235 | set -e | |
236 | chain=$1 | |
237 | for p in tcp udp; do | |
0291d6d5 | 238 | run ip46tables -A $chain -j ACCEPT \ |
bfdc045d MW |
239 | -m state --state ESTABLISHED \ |
240 | -p $p --source-port 53 | |
241 | done | |
242 | } | |
243 | ||
244 | ## openports CHAIN [MIN MAX] | |
245 | ## | |
246 | ## Add rules to CHAIN to allow the open ports. | |
247 | openports () { | |
248 | set -e | |
249 | chain=$1; shift | |
250 | [ $# -eq 0 ] && set -- $open_port_min $open_port_max | |
0291d6d5 MW |
251 | run ip46tables -A $chain -p tcp -g interesting --destination-port $1:$2 |
252 | run ip46tables -A $chain -p udp -g interesting --destination-port $1:$2 | |
bfdc045d MW |
253 | } |
254 | ||
255 | m4_divert(28)m4_dnl | |
256 | ###-------------------------------------------------------------------------- | |
257 | ### Packet classification. | |
258 | ||
259 | ## defbitfield NAME WIDTH | |
260 | ## | |
261 | ## Defines MASK_NAME and BIT_NAME symbolic constants for dealing with | |
262 | ## bitfields: x << BIT_NAME yields the value x in the correct position, and | |
263 | ## ff & MASK_NAME extracts the corresponding value. | |
264 | defbitfield () { | |
265 | set -e | |
266 | name=$1 width=$2 | |
267 | eval MASK_$name=$(( (1 << $width) - 1 << $bitindex )) | |
268 | eval BIT_$name=$bitindex | |
269 | bitindex=$(( $bitindex + $width )) | |
270 | } | |
271 | ||
272 | ## Define the layout of the bitfield. | |
273 | bitindex=0 | |
274 | defbitfield MASK 16 | |
275 | defbitfield FROM 4 | |
276 | defbitfield TO 4 | |
277 | ||
278 | ## defnetclass NAME FORWARD-TO... | |
279 | ## | |
280 | ## Defines a netclass called NAME, which is allowed to forward to the | |
281 | ## FORWARD-TO netclasses. | |
282 | ## | |
283 | ## For each netclass, constants from_NAME and to_NAME are defined as the | |
284 | ## appropriate values in the FROM and TO fields (i.e., not including any mask | |
285 | ## bits). | |
286 | ## | |
287 | ## This function also establishes mangle chains mark-from-NAME and | |
288 | ## mark-to-NAME for applying the appropriate mark bits to the packet. | |
289 | ## | |
290 | ## Because it needs to resolve forward references, netclasses must be defined | |
291 | ## in a two-pass manner, using a loop of the form | |
292 | ## | |
293 | ## for pass in 1 2; do netclassindex=0; ...; done | |
294 | netclassess= | |
295 | defnetclass () { | |
296 | set -e | |
297 | name=$1; shift | |
298 | case $pass in | |
299 | 1) | |
300 | ||
301 | ## Pass 1. Establish the from_NAME and to_NAME constants, and the | |
302 | ## netclass's mask bit. | |
303 | eval from_$name=$(( $netclassindex << $BIT_FROM )) | |
304 | eval to_$name=$(( $netclassindex << $BIT_TO )) | |
305 | eval _mask_$name=$(( 1 << ($netclassindex + $BIT_MASK) )) | |
306 | nets="$nets $name" | |
307 | ;; | |
308 | 2) | |
309 | ||
310 | ## Pass 2. Compute the actual from and to values. We're a little bit | |
311 | ## clever during source classification, and set the TO field to | |
312 | ## all-bits-one, so that destination classification needs only a single | |
313 | ## AND operation. | |
314 | from=$(( ($netclassindex << $BIT_FROM) + (0xf << $BIT_TO) )) | |
315 | for net; do | |
316 | eval bit=\$_mask_$net | |
317 | from=$(( $from + $bit )) | |
318 | done | |
319 | to=$(( ($netclassindex << $BIT_TO) + \ | |
12ac65a1 | 320 | (0xf << $BIT_FROM) + \ |
bfdc045d MW |
321 | (1 << ($netclassindex + $BIT_MASK)) )) |
322 | trace "from $name --> set $(printf %x $from)" | |
323 | trace " to $name --> and $(printf %x $from)" | |
324 | ||
325 | ## Now establish the mark-from-NAME and mark-to-NAME chains. | |
326 | clearchain mangle:mark-from-$name mangle:mark-to-$name | |
0291d6d5 MW |
327 | run ip46tables -t mangle -A mark-from-$name -j MARK --set-mark $from |
328 | run ip46tables -t mangle -A mark-to-$name -j MARK --and-mark $to | |
bfdc045d MW |
329 | ;; |
330 | esac | |
331 | netclassindex=$(( $netclassindex + 1 )) | |
332 | } | |
333 | ||
46be9bde | 334 | ## defiface NAME[,NAME,...] NETCLASS:NETWORK/MASK... |
bfdc045d | 335 | ## |
46be9bde MW |
336 | ## Declares network interfaces with the given NAMEs and associates with them |
337 | ## a number of reachable networks. During source classification, a packet | |
338 | ## arriving on interface NAME from an address in NETWORK/MASK is classified | |
339 | ## as coming from to NETCLASS. During destination classification, all | |
340 | ## packets going to NETWORK/MASK are classified as going to NETCLASS, | |
341 | ## regardless of interface (which is good, because the outgoing interface | |
342 | ## hasn't been determined yet). | |
bfdc045d MW |
343 | ## |
344 | ## As a special case, the NETWORK/MASK can be the string `default', which | |
345 | ## indicates that all addresses not matched elsewhere should be considered. | |
346 | ifaces=: | |
3a68f688 | 347 | defaultifaces="" |
0291d6d5 | 348 | allnets= allnets6= |
bfdc045d MW |
349 | defiface () { |
350 | set -e | |
46be9bde MW |
351 | names=$1; shift |
352 | seen=: | |
353 | for name in $(echo $names | sed 'y/,/ /'); do | |
354 | case $seen in *:"$name":*) continue ;; esac | |
355 | seen=$seen$name: | |
356 | case $ifaces in | |
357 | *:"$name":*) ;; | |
bfdc045d | 358 | *) |
46be9bde MW |
359 | clearchain mangle:in-$name |
360 | run ip46tables -t mangle -A in-classify -i $name -g in-$name | |
bfdc045d MW |
361 | ;; |
362 | esac | |
46be9bde MW |
363 | ifaces=$ifaces$name: |
364 | for item; do | |
365 | netclass=${item%:*} addr=${item#*:} | |
366 | case $addr in | |
367 | default) | |
3a68f688 MW |
368 | case "$defaultifaces,$defaultclass" in |
369 | ,* | *,$netclass) | |
370 | defaultifaces="$defaultifaces $name" | |
371 | defaultclass=$netclass | |
372 | ;; | |
373 | *) | |
374 | echo >&2 "$0: inconsistent default netclasses" | |
375 | exit 1 | |
376 | ;; | |
377 | esac | |
46be9bde MW |
378 | ;; |
379 | *:*) | |
380 | run ip6tables -t mangle -A in-$name -g mark-from-$netclass \ | |
381 | -s $addr | |
382 | run ip6tables -t mangle -A out-classify -g mark-to-$netclass \ | |
383 | -d $addr | |
384 | allnets6="$allnets6 $name:$addr" | |
385 | ;; | |
386 | *) | |
387 | run iptables -t mangle -A in-$name -g mark-from-$netclass \ | |
388 | -s $addr | |
389 | run iptables -t mangle -A out-classify -g mark-to-$netclass \ | |
390 | -d $addr | |
391 | allnets="$allnets $name:$addr" | |
392 | ;; | |
393 | esac | |
394 | done | |
bfdc045d MW |
395 | done |
396 | } | |
397 | ||
398 | ## defvpn IFACE CLASS NET HOST:ADDR ... | |
399 | ## | |
400 | ## Defines a VPN interface. If the interface has the form `ROOT+' (i.e., a | |
401 | ## netfilter wildcard) then define a separate interface ROOTHOST routing to | |
402 | ## ADDR; otherwise just write a blanket rule allowing the whole NET. All | |
403 | ## addresses concerned are put in the named CLASS. | |
404 | defvpn () { | |
405 | set -e | |
406 | iface=$1 class=$2 net=$3; shift 3 | |
407 | case $iface in | |
408 | *-+) | |
409 | root=${iface%+} | |
410 | for host; do | |
0291d6d5 | 411 | name=${host%%:*} addr=${host#*:} |
bfdc045d MW |
412 | defiface $root$name $class:$addr |
413 | done | |
414 | ;; | |
415 | *) | |
416 | defiface $iface $class:$net | |
417 | ;; | |
418 | esac | |
419 | } | |
420 | ||
421 | m4_divert(-1) | |
422 | ###----- That's all, folks -------------------------------------------------- |