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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 | |
0f6364ac MW |
111 | opt=$1 val=$2 |
112 | any=nil | |
113 | for ver in ipv4 ipv6; do | |
114 | if [ -f /proc/sys/net/$ver/$opt ]; then | |
115 | run sysctl -q net/$ver/$opt="$val" | |
116 | any=t | |
117 | fi | |
118 | done | |
119 | case $any in | |
120 | nil) echo >&2 "$0: unknown IP option $opt"; exit 1 ;; | |
121 | esac | |
bfdc045d MW |
122 | } |
123 | ||
0f6364ac | 124 | ## setdevopt OPTION VALUE [INTERFACES ...] |
bfdc045d MW |
125 | ## |
126 | ## Set an IP interface-level sysctl. | |
127 | setdevopt () { | |
128 | set -e | |
0f6364ac MW |
129 | opt=$1 val=$2; shift 2 |
130 | case "$#,$1" in | |
131 | 0, | 1,all) | |
132 | set -- $( | |
133 | seen=: | |
134 | for ver in ipv4 ipv6; do | |
135 | cd /proc/sys/net/$ver/conf | |
136 | for i in *; do | |
137 | [ -f $i/$opt ] || continue | |
138 | case "$seen" in (*:$i:*) continue ;; esac | |
139 | echo $i | |
140 | done | |
141 | done) | |
142 | ;; | |
143 | esac | |
144 | for i in "$@"; do | |
145 | any=nil | |
146 | for ver in ipv4 ipv6; do | |
147 | if [ -f /proc/sys/net/$ver/conf/$i/$opt ]; then | |
148 | any=t | |
149 | run sysctl -q net/ipv4/conf/$i/$opt="$val" | |
150 | fi | |
151 | done | |
152 | case $any in | |
153 | nil) echo >&2 "$0: unknown device option $opt"; exit 1 ;; | |
154 | esac | |
bfdc045d MW |
155 | done |
156 | } | |
157 | ||
158 | m4_divert(26)m4_dnl | |
159 | ###-------------------------------------------------------------------------- | |
160 | ### Packet filter construction. | |
161 | ||
162 | ## conntrack CHAIN | |
163 | ## | |
164 | ## Add connection tracking to CHAIN, and allow obvious stuff. | |
165 | conntrack () { | |
166 | set -e | |
167 | chain=$1 | |
0291d6d5 | 168 | run ip46tables -A $chain -p tcp -m state \ |
bfdc045d | 169 | --state ESTABLISHED,RELATED -j ACCEPT |
0291d6d5 | 170 | run ip46tables -A $chain -p tcp ! --syn -g bad-tcp |
bfdc045d MW |
171 | } |
172 | ||
ecdca131 MW |
173 | ## commonrules CHAIN |
174 | ## | |
175 | ## Add standard IP filtering rules to the CHAIN. | |
176 | commonrules () { | |
177 | set -e | |
178 | chain=$1 | |
179 | ||
180 | ## Pass fragments through, assuming that the eventual destination will sort | |
181 | ## things out properly. Except for TCP, that is, which should never be | |
c70bfbbb MW |
182 | ## fragmented. This is an extra pain for ip6tables, which doesn't provide |
183 | ## a pleasant way to detect non-initial fragments. | |
ecdca131 MW |
184 | run iptables -A $chain -p tcp -f -g tcp-fragment |
185 | run iptables -A $chain -f -j ACCEPT | |
0291d6d5 MW |
186 | run ip6tables -A $chain -p tcp -g tcp-fragment \ |
187 | -m ipv6header --soft --header frag | |
c70bfbbb | 188 | run ip6tables -A $chain -j accept-non-init-frag |
ecdca131 MW |
189 | } |
190 | ||
c70bfbbb MW |
191 | m4_divert(38)m4_dnl |
192 | ## Accept a non-initial fragment. This is only needed by IPv6, to work | |
193 | ## around a deficiency in the option parser. | |
194 | run ip6tables -N accept-non-init-frag | |
195 | run ip6tables -A accept-non-init-frag -j RETURN \ | |
196 | -m frag --fragfirst | |
197 | run ip6tables -A accept-non-init-frag -j ACCEPT | |
198 | ||
199 | m4_divert(26)m4_dnl | |
bfdc045d MW |
200 | ## allowservices CHAIN PROTO SERVICE ... |
201 | ## | |
202 | ## Add rules to allow the SERVICES on the CHAIN. | |
203 | allowservices () { | |
204 | set -e | |
205 | chain=$1 proto=$2; shift 2 | |
206 | count=0 | |
207 | list= | |
208 | for svc; do | |
209 | case $svc in | |
210 | *:*) | |
12ac65a1 | 211 | n=2 |
bfdc045d MW |
212 | left=${svc%:*} right=${svc#*:} |
213 | case $left in *[!0-9]*) eval left=\$port_$left ;; esac | |
214 | case $right in *[!0-9]*) eval right=\$port_$right ;; esac | |
215 | svc=$left:$right | |
216 | ;; | |
217 | *) | |
12ac65a1 | 218 | n=1 |
bfdc045d MW |
219 | case $svc in *[!0-9]*) eval svc=\$port_$svc ;; esac |
220 | ;; | |
221 | esac | |
222 | case $svc in | |
223 | *: | :* | "" | *[!0-9:]*) | |
12ac65a1 | 224 | echo >&2 "Bad service name" |
bfdc045d MW |
225 | exit 1 |
226 | ;; | |
227 | esac | |
228 | count=$(( $count + $n )) | |
229 | if [ $count -gt 15 ]; then | |
0291d6d5 | 230 | run ip46tables -A $chain -p $proto -m multiport -j ACCEPT \ |
bfdc045d MW |
231 | --destination-ports ${list#,} |
232 | list= count=$n | |
233 | fi | |
234 | list=$list,$svc | |
235 | done | |
236 | case $list in | |
237 | "") | |
238 | ;; | |
239 | ,*,*) | |
0291d6d5 | 240 | run ip46tables -A $chain -p $proto -m multiport -j ACCEPT \ |
bfdc045d MW |
241 | --destination-ports ${list#,} |
242 | ;; | |
12ac65a1 | 243 | *) |
0291d6d5 | 244 | run ip46tables -A $chain -p $proto -j ACCEPT \ |
bfdc045d MW |
245 | --destination-port ${list#,} |
246 | ;; | |
247 | esac | |
248 | } | |
249 | ||
250 | ## ntpclient CHAIN NTPSERVER ... | |
251 | ## | |
252 | ## Add rules to CHAIN to allow NTP with NTPSERVERs. | |
253 | ntpclient () { | |
254 | set -e | |
255 | chain=$1; shift | |
256 | for ntp; do | |
257 | run iptables -A $chain -s $ntp -j ACCEPT \ | |
258 | -p udp --source-port 123 --destination-port 123 | |
259 | done | |
260 | } | |
261 | ||
262 | ## dnsresolver CHAIN | |
263 | ## | |
264 | ## Add rules to allow CHAIN to be a DNS resolver. | |
265 | dnsresolver () { | |
266 | set -e | |
267 | chain=$1 | |
268 | for p in tcp udp; do | |
0291d6d5 | 269 | run ip46tables -A $chain -j ACCEPT \ |
bfdc045d MW |
270 | -m state --state ESTABLISHED \ |
271 | -p $p --source-port 53 | |
272 | done | |
273 | } | |
274 | ||
275 | ## openports CHAIN [MIN MAX] | |
276 | ## | |
277 | ## Add rules to CHAIN to allow the open ports. | |
278 | openports () { | |
279 | set -e | |
280 | chain=$1; shift | |
281 | [ $# -eq 0 ] && set -- $open_port_min $open_port_max | |
0291d6d5 MW |
282 | run ip46tables -A $chain -p tcp -g interesting --destination-port $1:$2 |
283 | run ip46tables -A $chain -p udp -g interesting --destination-port $1:$2 | |
bfdc045d MW |
284 | } |
285 | ||
286 | m4_divert(28)m4_dnl | |
287 | ###-------------------------------------------------------------------------- | |
288 | ### Packet classification. | |
289 | ||
290 | ## defbitfield NAME WIDTH | |
291 | ## | |
292 | ## Defines MASK_NAME and BIT_NAME symbolic constants for dealing with | |
293 | ## bitfields: x << BIT_NAME yields the value x in the correct position, and | |
294 | ## ff & MASK_NAME extracts the corresponding value. | |
295 | defbitfield () { | |
296 | set -e | |
297 | name=$1 width=$2 | |
298 | eval MASK_$name=$(( (1 << $width) - 1 << $bitindex )) | |
299 | eval BIT_$name=$bitindex | |
300 | bitindex=$(( $bitindex + $width )) | |
301 | } | |
302 | ||
303 | ## Define the layout of the bitfield. | |
304 | bitindex=0 | |
305 | defbitfield MASK 16 | |
306 | defbitfield FROM 4 | |
307 | defbitfield TO 4 | |
308 | ||
309 | ## defnetclass NAME FORWARD-TO... | |
310 | ## | |
311 | ## Defines a netclass called NAME, which is allowed to forward to the | |
312 | ## FORWARD-TO netclasses. | |
313 | ## | |
314 | ## For each netclass, constants from_NAME and to_NAME are defined as the | |
315 | ## appropriate values in the FROM and TO fields (i.e., not including any mask | |
316 | ## bits). | |
317 | ## | |
318 | ## This function also establishes mangle chains mark-from-NAME and | |
319 | ## mark-to-NAME for applying the appropriate mark bits to the packet. | |
320 | ## | |
321 | ## Because it needs to resolve forward references, netclasses must be defined | |
322 | ## in a two-pass manner, using a loop of the form | |
323 | ## | |
324 | ## for pass in 1 2; do netclassindex=0; ...; done | |
325 | netclassess= | |
326 | defnetclass () { | |
327 | set -e | |
328 | name=$1; shift | |
329 | case $pass in | |
330 | 1) | |
331 | ||
332 | ## Pass 1. Establish the from_NAME and to_NAME constants, and the | |
333 | ## netclass's mask bit. | |
334 | eval from_$name=$(( $netclassindex << $BIT_FROM )) | |
335 | eval to_$name=$(( $netclassindex << $BIT_TO )) | |
336 | eval _mask_$name=$(( 1 << ($netclassindex + $BIT_MASK) )) | |
337 | nets="$nets $name" | |
338 | ;; | |
339 | 2) | |
340 | ||
341 | ## Pass 2. Compute the actual from and to values. We're a little bit | |
342 | ## clever during source classification, and set the TO field to | |
343 | ## all-bits-one, so that destination classification needs only a single | |
344 | ## AND operation. | |
345 | from=$(( ($netclassindex << $BIT_FROM) + (0xf << $BIT_TO) )) | |
346 | for net; do | |
347 | eval bit=\$_mask_$net | |
348 | from=$(( $from + $bit )) | |
349 | done | |
350 | to=$(( ($netclassindex << $BIT_TO) + \ | |
12ac65a1 | 351 | (0xf << $BIT_FROM) + \ |
bfdc045d MW |
352 | (1 << ($netclassindex + $BIT_MASK)) )) |
353 | trace "from $name --> set $(printf %x $from)" | |
354 | trace " to $name --> and $(printf %x $from)" | |
355 | ||
356 | ## Now establish the mark-from-NAME and mark-to-NAME chains. | |
357 | clearchain mangle:mark-from-$name mangle:mark-to-$name | |
0291d6d5 MW |
358 | run ip46tables -t mangle -A mark-from-$name -j MARK --set-mark $from |
359 | run ip46tables -t mangle -A mark-to-$name -j MARK --and-mark $to | |
bfdc045d MW |
360 | ;; |
361 | esac | |
362 | netclassindex=$(( $netclassindex + 1 )) | |
363 | } | |
364 | ||
46be9bde | 365 | ## defiface NAME[,NAME,...] NETCLASS:NETWORK/MASK... |
bfdc045d | 366 | ## |
46be9bde MW |
367 | ## Declares network interfaces with the given NAMEs and associates with them |
368 | ## a number of reachable networks. During source classification, a packet | |
369 | ## arriving on interface NAME from an address in NETWORK/MASK is classified | |
370 | ## as coming from to NETCLASS. During destination classification, all | |
371 | ## packets going to NETWORK/MASK are classified as going to NETCLASS, | |
372 | ## regardless of interface (which is good, because the outgoing interface | |
373 | ## hasn't been determined yet). | |
bfdc045d MW |
374 | ## |
375 | ## As a special case, the NETWORK/MASK can be the string `default', which | |
376 | ## indicates that all addresses not matched elsewhere should be considered. | |
377 | ifaces=: | |
3a68f688 | 378 | defaultifaces="" |
0291d6d5 | 379 | allnets= allnets6= |
bfdc045d MW |
380 | defiface () { |
381 | set -e | |
46be9bde MW |
382 | names=$1; shift |
383 | seen=: | |
384 | for name in $(echo $names | sed 'y/,/ /'); do | |
385 | case $seen in *:"$name":*) continue ;; esac | |
386 | seen=$seen$name: | |
387 | case $ifaces in | |
388 | *:"$name":*) ;; | |
bfdc045d | 389 | *) |
46be9bde MW |
390 | clearchain mangle:in-$name |
391 | run ip46tables -t mangle -A in-classify -i $name -g in-$name | |
bfdc045d MW |
392 | ;; |
393 | esac | |
46be9bde MW |
394 | ifaces=$ifaces$name: |
395 | for item; do | |
396 | netclass=${item%:*} addr=${item#*:} | |
397 | case $addr in | |
398 | default) | |
3a68f688 MW |
399 | case "$defaultifaces,$defaultclass" in |
400 | ,* | *,$netclass) | |
401 | defaultifaces="$defaultifaces $name" | |
402 | defaultclass=$netclass | |
403 | ;; | |
404 | *) | |
405 | echo >&2 "$0: inconsistent default netclasses" | |
406 | exit 1 | |
407 | ;; | |
408 | esac | |
46be9bde MW |
409 | ;; |
410 | *:*) | |
411 | run ip6tables -t mangle -A in-$name -g mark-from-$netclass \ | |
412 | -s $addr | |
413 | run ip6tables -t mangle -A out-classify -g mark-to-$netclass \ | |
414 | -d $addr | |
415 | allnets6="$allnets6 $name:$addr" | |
416 | ;; | |
417 | *) | |
418 | run iptables -t mangle -A in-$name -g mark-from-$netclass \ | |
419 | -s $addr | |
420 | run iptables -t mangle -A out-classify -g mark-to-$netclass \ | |
421 | -d $addr | |
422 | allnets="$allnets $name:$addr" | |
423 | ;; | |
424 | esac | |
425 | done | |
bfdc045d MW |
426 | done |
427 | } | |
428 | ||
429 | ## defvpn IFACE CLASS NET HOST:ADDR ... | |
430 | ## | |
431 | ## Defines a VPN interface. If the interface has the form `ROOT+' (i.e., a | |
432 | ## netfilter wildcard) then define a separate interface ROOTHOST routing to | |
433 | ## ADDR; otherwise just write a blanket rule allowing the whole NET. All | |
434 | ## addresses concerned are put in the named CLASS. | |
435 | defvpn () { | |
436 | set -e | |
437 | iface=$1 class=$2 net=$3; shift 3 | |
438 | case $iface in | |
439 | *-+) | |
440 | root=${iface%+} | |
441 | for host; do | |
0291d6d5 | 442 | name=${host%%:*} addr=${host#*:} |
bfdc045d MW |
443 | defiface $root$name $class:$addr |
444 | done | |
445 | ;; | |
446 | *) | |
447 | defiface $iface $class:$net | |
448 | ;; | |
449 | esac | |
450 | } | |
451 | ||
452 | m4_divert(-1) | |
453 | ###----- That's all, folks -------------------------------------------------- |