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