src/ferm

   1 #!/usr/bin/perl
   2
   3 #
   4 # ferm, a firewall setup program that makes firewall rules easy!
   5 #
   6 # Copyright (C) 2001-2012 Max Kellermann, Auke Kok
   7 #
   8 # Comments, questions, greetings and additions to this program
   9 # may be sent to <ferm@foo-projects.org>
  10 #
  11
  12 #
  13 # This program is free software; you can redistribute it and/or modify
  14 # it under the terms of the GNU General Public License as published by
  15 # the Free Software Foundation; either version 2 of the License, or
  16 # (at your option) any later version.
  17 #
  18 # This program is distributed in the hope that it will be useful,
  19 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 # GNU General Public License for more details.
  22 #
  23 # You should have received a copy of the GNU General Public License
  24 # along with this program; if not, write to the Free Software
  25 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  26 #
  27
  28 # $Id$
  29
  30 use File::Spec;
  31
  32 BEGIN {
  33     eval { require strict; import strict; };
  34     $has_strict = not $@;
  35     if ($@) {
  36         # we need no vars.pm if there is not even strict.pm
  37         $INC{'vars.pm'} = 1;
  38         *vars::import = sub {};
  39     } else {
  40         require IO::Handle;
  41     }
  42
  43     eval { require Getopt::Long; import Getopt::Long; };
  44     $has_getopt = not $@;
  45 }
  46
  47 use vars qw($has_strict $has_getopt);
  48
  49 use vars qw($VERSION);
  50
  51 $VERSION = '2.2.1';
  52 $VERSION .= '~git';
  53
  54 ## interface variables
  55 # %option = command line and other options
  56 use vars qw(%option);
  57
  58 ## hooks
  59 use vars qw(@pre_hooks @post_hooks @flush_hooks);
  60
  61 ## parser variables
  62 # $script: current script file
  63 # @stack = ferm's parser stack containing local variables
  64 # $auto_chain = index for the next auto-generated chain
  65 use vars qw($script @stack $auto_chain);
  66
  67 ## netfilter variables
  68 # %domains = state information about all domains ("ip" and "ip6")
  69 # - initialized: domain initialization is done
  70 # - tools: hash providing the paths of the domain's tools
  71 # - previous: save file of the previous ruleset, for rollback
  72 # - tables{$name}: ferm state information about tables
  73 #   - has_builtin: whether built-in chains have been determined in this table
  74 #   - chains{$chain}: ferm state information about the chains
  75 #     - builtin: whether this is a built-in chain
  76 use vars qw(%domains);
  77
  78 ## constants
  79 use vars qw(%deprecated_keywords);
  80
  81 # keywords from ferm 1.1 which are deprecated, and the new one; these
  82 # are automatically replaced, and a warning is printed
  83 %deprecated_keywords = ( goto => 'jump',
  84                        );
  85
  86 # these hashes provide the Netfilter module definitions
  87 use vars qw(%proto_defs %match_defs %target_defs);
  88
  89 #
  90 # This subsubsystem allows you to support (most) new netfilter modules
  91 # in ferm.  Add a call to one of the "add_XY_def()" functions below.
  92 #
  93 # Ok, now about the cryptic syntax: the function "add_XY_def()"
  94 # registers a new module.  There are three kinds of modules: protocol
  95 # module (e.g. TCP, ICMP), match modules (e.g. state, physdev) and
  96 # target modules (e.g. DNAT, MARK).
  97 #
  98 # The first parameter is always the module name which is passed to
  99 # iptables with "-p", "-m" or "-j" (depending on which kind of module
 100 # this is).
 101 #
 102 # After that, you add an encoded string for each option the module
 103 # supports.  This is where it becomes tricky.
 104 #
 105 # foo           defaults to an option with one argument (which may be a ferm
 106 #               array)
 107 #
 108 # foo*0         option without any arguments
 109 #
 110 # foo=s         one argument which must not be a ferm array ('s' stands for
 111 #               'scalar')
 112 #
 113 # u32=m         an array which renders into multiple iptables options in one
 114 #               rule
 115 #
 116 # ctstate=c     one argument, if it's an array, pass it to iptables as a
 117 #               single comma separated value; example:
 118 #                 ctstate (ESTABLISHED RELATED)  translates to:
 119 #                 --ctstate ESTABLISHED,RELATED
 120 #
 121 # foo=sac       three arguments: scalar, array, comma separated; you may
 122 #               concatenate more than one letter code after the '='
 123 #
 124 # foo&bar       one argument; call the perl function '&bar()' which parses
 125 #               the argument
 126 #
 127 # !foo          negation is allowed and the '!' is written before the keyword
 128 #
 129 # foo!          same as above, but '!' is after the keyword and before the
 130 #               parameters
 131 #
 132 # to:=to-destination    makes "to" an alias for "to-destination"; you have
 133 #                       to add a declaration for option "to-destination"
 134 #
 135
 136 # prototype declarations
 137 sub open_script($);
 138 sub resolve($\@$);
 139 sub enter($$);
 140 sub rollback();
 141 sub execute_fast($);
 142 sub execute_slow($);
 143 sub join_value($$);
 144 sub ipfilter($@);
 145
 146 # add a module definition
 147 sub add_def_x {
 148     my $defs = shift;
 149     my $domain_family = shift;
 150     my $params_default = shift;
 151     my $name = shift;
 152     die if exists $defs->{$domain_family}{$name};
 153     my $def = $defs->{$domain_family}{$name} = {};
 154     foreach (@_) {
 155         my $keyword = $_;
 156         my $k;
 157
 158         if ($keyword =~ s,:=(\S+)$,,) {
 159             $k = $def->{keywords}{$1} || die;
 160             $k->{ferm_name} ||= $keyword;
 161         } else {
 162             my $params = $params_default;
 163             $params = $1 if $keyword =~ s,\*(\d+)$,,;
 164             $params = $1 if $keyword =~ s,=([acs]+|m)$,,;
 165             if ($keyword =~ s,&(\S+)$,,) {
 166                 $params = eval "\\&$1";
 167                 die $@ if $@;
 168             }
 169
 170             $k = {};
 171             $k->{params} = $params if $params;
 172
 173             $k->{negation} = $k->{pre_negation} = 1 if $keyword =~ s,^!,,;
 174             $k->{negation} = 1 if $keyword =~ s,!$,,;
 175             $k->{name} = $keyword;
 176         }
 177
 178         $def->{keywords}{$keyword} = $k;
 179     }
 180
 181     return $def;
 182 }
 183
 184 # add a protocol module definition
 185 sub add_proto_def_x(@) {
 186     my $domain_family = shift;
 187     add_def_x(\%proto_defs, $domain_family, 1, @_);
 188 }
 189
 190 # add a match module definition
 191 sub add_match_def_x(@) {
 192     my $domain_family = shift;
 193     add_def_x(\%match_defs, $domain_family, 1, @_);
 194 }
 195
 196 # add a target module definition
 197 sub add_target_def_x(@) {
 198     my $domain_family = shift;
 199     add_def_x(\%target_defs, $domain_family, 's', @_);
 200 }
 201
 202 sub add_def {
 203     my $defs = shift;
 204     add_def_x($defs, 'ip', @_);
 205 }
 206
 207 # add a protocol module definition
 208 sub add_proto_def(@) {
 209     add_def(\%proto_defs, 1, @_);
 210 }
 211
 212 # add a match module definition
 213 sub add_match_def(@) {
 214     add_def(\%match_defs, 1, @_);
 215 }
 216
 217 # add a target module definition
 218 sub add_target_def(@) {
 219     add_def(\%target_defs, 's', @_);
 220 }
 221
 222 add_proto_def 'dccp', qw(dccp-types!=c dccp-option!);
 223 add_proto_def 'mh', qw(mh-type!);
 224 add_proto_def 'icmp', qw(icmp-type! icmpv6-type:=icmp-type);
 225 add_proto_def 'sctp', qw(chunk-types!=sc);
 226 add_proto_def 'tcp', qw(tcp-flags!=cc !syn*0 tcp-option! mss);
 227 add_proto_def 'udp', qw();
 228
 229 add_match_def '',
 230   # --source, --destination
 231   qw(source!&address_magic saddr:=source),
 232   qw(destination!&address_magic daddr:=destination),
 233   # --in-interface
 234   qw(in-interface! interface:=in-interface if:=in-interface),
 235   # --out-interface
 236   qw(out-interface! outerface:=out-interface of:=out-interface),
 237   # --fragment
 238   qw(!fragment*0);
 239 add_match_def 'account', qw(aaddr=s aname=s ashort*0);
 240 add_match_def 'addrtype', qw(!src-type !dst-type),
 241   qw(limit-iface-in*0 limit-iface-out*0);
 242 add_match_def 'ah', qw(ahspi! ahlen! ahres*0);
 243 add_match_def 'comment', qw(comment=s);
 244 add_match_def 'condition', qw(condition!);
 245 add_match_def 'connbytes', qw(!connbytes connbytes-dir connbytes-mode);
 246 add_match_def 'connlimit', qw(!connlimit-above connlimit-mask);
 247 add_match_def 'connmark', qw(!mark);
 248 add_match_def 'conntrack', qw(!ctstate=c !ctproto ctorigsrc! ctorigdst! ctorigsrcport! ctorigdstport!),
 249   qw(ctreplsrc! ctrepldst! !ctstatus !ctexpire=s ctdir=s);
 250 add_match_def 'dscp', qw(dscp dscp-class);
 251 add_match_def 'ecn', qw(ecn-tcp-cwr*0 ecn-tcp-ece*0 ecn-ip-ect);
 252 add_match_def 'esp', qw(espspi!);
 253 add_match_def 'eui64';
 254 add_match_def 'fuzzy', qw(lower-limit=s upper-limit=s);
 255 add_match_def 'hbh', qw(hbh-len! hbh-opts=c);
 256 add_match_def 'helper', qw(helper);
 257 add_match_def 'hl', qw(hl-eq! hl-lt=s hl-gt=s);
 258 add_match_def 'hashlimit', qw(hashlimit=s hashlimit-burst=s hashlimit-mode=c hashlimit-name=s),
 259   qw(hashlimit-htable-size=s hashlimit-htable-max=s),
 260   qw(hashlimit-htable-expire=s hashlimit-htable-gcinterval=s);
 261 add_match_def 'iprange', qw(!src-range !dst-range);
 262 add_match_def 'ipv4options', qw(ssrr*0 lsrr*0 no-srr*0 !rr*0 !ts*0 !ra*0 !any-opt*0);
 263 add_match_def 'ipv6header', qw(header!=c soft*0);
 264 add_match_def 'length', qw(length!);
 265 add_match_def 'limit', qw(limit=s limit-burst=s);
 266 add_match_def 'mac', qw(mac-source!);
 267 add_match_def 'mark', qw(!mark);
 268 add_match_def 'multiport', qw(source-ports!&multiport_params),
 269   qw(destination-ports!&multiport_params ports!&multiport_params);
 270 add_match_def 'nth', qw(every counter start packet);
 271 add_match_def 'osf', qw(!genre ttl=s log=s);
 272 add_match_def 'owner', qw(!uid-owner !gid-owner pid-owner sid-owner),
 273   qw(cmd-owner !socket-exists=0);
 274 add_match_def 'physdev', qw(physdev-in! physdev-out!),
 275   qw(!physdev-is-in*0 !physdev-is-out*0 !physdev-is-bridged*0);
 276 add_match_def 'pkttype', qw(pkt-type!),
 277 add_match_def 'policy',
 278   qw(dir pol strict*0 !reqid !spi !proto !mode !tunnel-src !tunnel-dst next*0);
 279 add_match_def 'psd', qw(psd-weight-threshold psd-delay-threshold),
 280   qw(psd-lo-ports-weight psd-hi-ports-weight);
 281 add_match_def 'quota', qw(quota=s);
 282 add_match_def 'random', qw(average);
 283 add_match_def 'realm', qw(realm!);
 284 add_match_def 'recent', qw(name=s !set*0 !remove*0 !rcheck*0 !update*0 !seconds !hitcount rttl*0 rsource*0 rdest*0);
 285 add_match_def 'rt', qw(rt-type! rt-segsleft! rt-len! rt-0-res*0 rt-0-addrs=c rt-0-not-strict*0);
 286 add_match_def 'set', qw(!match-set=sc set:=match-set);
 287 add_match_def 'state', qw(!state=c);
 288 add_match_def 'statistic', qw(mode=s probability=s every=s packet=s);
 289 add_match_def 'string', qw(algo=s from=s to=s string hex-string);
 290 add_match_def 'tcpmss', qw(!mss);
 291 add_match_def 'time', qw(timestart=s timestop=s days=c datestart=s datestop=s),
 292   qw(!monthday=c !weekdays=c utc*0 localtz*0);
 293 add_match_def 'tos', qw(!tos);
 294 add_match_def 'ttl', qw(ttl-eq ttl-lt=s ttl-gt=s);
 295 add_match_def 'u32', qw(!u32=m);
 296
 297 add_target_def 'BALANCE', qw(to-destination to:=to-destination);
 298 add_target_def 'CHECKSUM', qw(checksum-fill*0);
 299 add_target_def 'CLASSIFY', qw(set-class);
 300 add_target_def 'CLUSTERIP', qw(new*0 hashmode clustermac total-nodes local-node hash-init);
 301 add_target_def 'CONNMARK', qw(set-mark save-mark*0 restore-mark*0 mask);
 302 add_target_def 'CONNSECMARK', qw(save*0 restore*0);
 303 add_target_def 'CT', qw(notrack*0 helper ctevents=c expevents=c zone timeout);
 304 add_target_def 'DNAT', qw(to-destination=m to:=to-destination persistent*0 random*0);
 305 add_target_def 'DSCP', qw(set-dscp set-dscp-class);
 306 add_target_def 'ECN', qw(ecn-tcp-remove*0);
 307 add_target_def 'HL', qw(hl-set hl-dec hl-inc);
 308 add_target_def 'IPV4OPTSSTRIP';
 309 add_target_def 'LOG', qw(log-level log-prefix),
 310   qw(log-tcp-sequence*0 log-tcp-options*0 log-ip-options*0 log-uid*0);
 311 add_target_def 'MARK', qw(set-mark set-xmark and-mark or-mark xor-mark);
 312 add_target_def 'MASQUERADE', qw(to-ports random*0);
 313 add_target_def 'MIRROR';
 314 add_target_def 'NETMAP', qw(to);
 315 add_target_def 'NFLOG', qw(nflog-group nflog-prefix nflog-range nflog-threshold);
 316 add_target_def 'NFQUEUE', qw(queue-num queue-balance queue-bypass*0 queue-cpu-fanout*0);
 317 add_target_def 'NOTRACK';
 318 add_target_def 'REDIRECT', qw(to-ports random*0);
 319 add_target_def 'REJECT', qw(reject-with);
 320 add_target_def 'ROUTE', qw(oif iif gw continue*0 tee*0);
 321 add_target_def 'SAME', qw(to nodst*0 random*0);
 322 add_target_def 'SECMARK', qw(selctx);
 323 add_target_def 'SET', qw(add-set=sc del-set=sc);
 324 add_target_def 'SNAT', qw(to-source=m to:=to-source persistent*0 random*0);
 325 add_target_def 'TARPIT';
 326 add_target_def 'TCPMSS', qw(set-mss clamp-mss-to-pmtu*0);
 327 add_target_def 'TEE', qw(gateway);
 328 add_target_def 'TOS', qw(set-tos and-tos or-tos xor-tos);
 329 add_target_def 'TPROXY', qw(tproxy-mark on-port);
 330 add_target_def 'TRACE';
 331 add_target_def 'TTL', qw(ttl-set ttl-dec ttl-inc);
 332 add_target_def 'ULOG', qw(ulog-nlgroup ulog-prefix ulog-cprange ulog-qthreshold);
 333
 334 add_match_def_x 'arp', '',
 335   # ip
 336   qw(source-ip! destination-ip! saddr:=source-ip daddr:=destination-ip),
 337   # mac
 338   qw(source-mac! destination-mac!),
 339   # --in-interface
 340   qw(in-interface! interface:=in-interface if:=in-interface),
 341   # --out-interface
 342   qw(out-interface! outerface:=out-interface of:=out-interface),
 343   # misc
 344   qw(h-length=s opcode=s h-type=s proto-type=s),
 345   qw(mangle-ip-s=s mangle-ip-d=s mangle-mac-s=s mangle-mac-d=s mangle-target=s);
 346
 347 add_proto_def_x 'eb', 'IPv4',
 348   qw(ip-source! ip-destination! ip-src:=ip-source ip-dst:=ip-destination),
 349   qw(ip-tos!),
 350   qw(ip-protocol! ip-proto:=ip-protocol),
 351   qw(ip-source-port! ip-sport:=ip-source-port),
 352   qw(ip-destination-port! ip-dport:=ip-destination-port);
 353
 354 add_proto_def_x 'eb', 'IPv6',
 355   qw(ip6-source! ip6-destination! ip6-src:=ip6-source ip6-dst:=ip6-destination),
 356   qw(ip6-tclass!),
 357   qw(ip6-protocol! ip6-proto:=ip6-protocol),
 358   qw(ip6-source-port! ip6-sport:=ip6-source-port),
 359   qw(ip6-destination-port! ip6-dport:=ip6-destination-port);
 360
 361 add_proto_def_x 'eb', 'ARP',
 362   qw(!arp-gratuitous*0),
 363   qw(arp-opcode! arp-htype!=ss arp-ptype!=ss),
 364   qw(arp-ip-src! arp-ip-dst! arp-mac-src! arp-mac-dst!);
 365
 366 add_proto_def_x 'eb', 'RARP',
 367   qw(!arp-gratuitous*0),
 368   qw(arp-opcode! arp-htype!=ss arp-ptype!=ss),
 369   qw(arp-ip-src! arp-ip-dst! arp-mac-src! arp-mac-dst!);
 370
 371 add_proto_def_x 'eb', '802_1Q',
 372   qw(vlan-id! vlan-prio! vlan-encap!),
 373
 374 add_match_def_x 'eb', '',
 375   # --in-interface
 376   qw(in-interface! interface:=in-interface if:=in-interface),
 377   # --out-interface
 378   qw(out-interface! outerface:=out-interface of:=out-interface),
 379   # logical interface
 380   qw(logical-in! logical-out!),
 381   # --source, --destination
 382   qw(source! saddr:=source destination! daddr:=destination),
 383   # 802.3
 384   qw(802_3-sap! 802_3-type!),
 385   # among
 386   qw(!among-dst=c !among-src=c !among-dst-file !among-src-file),
 387   # limit
 388   qw(limit=s limit-burst=s),
 389   # mark_m
 390   qw(mark!),
 391   # pkttype
 392   qw(pkttype-type!),
 393   # stp
 394   qw(stp-type! stp-flags! stp-root-prio! stp-root-addr! stp-root-cost!),
 395   qw(stp-sender-prio! stp-sender-addr! stp-port! stp-msg-age! stp-max-age!),
 396   qw(stp-hello-time! stp-forward-delay!),
 397   # log
 398   qw(log*0 log-level=s log-prefix=s log-ip*0 log-arp*0);
 399
 400 add_target_def_x 'eb', 'arpreply', qw(arpreply-mac arpreply-target);
 401 add_target_def_x 'eb', 'dnat', qw(to-destination dnat-target);
 402 add_target_def_x 'eb', 'MARK', qw(set-mark mark-target);
 403 add_target_def_x 'eb', 'redirect', qw(redirect-target);
 404 add_target_def_x 'eb', 'snat', qw(to-source snat-target snat-arp*0);
 405
 406 # import-ferm uses the above tables
 407 return 1 if $0 =~ /import-ferm$/;
 408
 409 # parameter parser for ipt_multiport
 410 sub multiport_params {
 411     my $rule = shift;
 412
 413     # multiport only allows 15 ports at a time. For this
 414     # reason, we do a little magic here: split the ports
 415     # into portions of 15, and handle these portions as
 416     # array elements
 417
 418     my $proto = $rule->{protocol};
 419     error('To use multiport, you have to specify "proto tcp" or "proto udp" first')
 420       unless defined $proto and grep { /^(?:tcp|udp|udplite)$/ } to_array($proto);
 421
 422     my $value = getvalues(undef, allow_negation => 1,
 423                           allow_array_negation => 1);
 424     if (ref $value and ref $value eq 'ARRAY') {
 425         my @value = @$value;
 426         my @params;
 427
 428         while (@value) {
 429             push @params, join(',', splice(@value, 0, 15));
 430         }
 431
 432         return @params == 1
 433           ? $params[0]
 434             : \@params;
 435     } else {
 436         return join_value(',', $value);
 437     }
 438 }
 439
 440 sub ipfilter($@) {
 441     my $domain = shift;
 442     my @ips;
 443     # very crude IPv4/IPv6 address detection
 444     if ($domain eq 'ip') {
 445         @ips = grep { !/:[0-9a-f]*:/ } @_;
 446     } elsif ($domain eq 'ip6') {
 447         @ips = grep { !m,^[0-9./]+$,s } @_;
 448     }
 449     return @ips;
 450 }
 451
 452 sub address_magic {
 453     my $rule = shift;
 454     my $domain = $rule->{domain};
 455     my $value = getvalues(undef, allow_negation => 1);
 456
 457     my @ips;
 458     my $negated = 0;
 459     if (ref $value and ref $value eq 'ARRAY') {
 460         @ips = @$value;
 461     } elsif (ref $value and ref $value eq 'negated') {
 462         @ips = @$value;
 463         $negated = 1;
 464     } elsif (ref $value) {
 465         die;
 466     } else {
 467         @ips = ($value);
 468     }
 469
 470     # only do magic on domain (ip ip6); do not process on a single-stack rule
 471     # as to let admins spot their errors instead of silently ignoring them
 472     @ips = ipfilter($domain, @ips) if defined $rule->{domain_both};
 473
 474     if ($negated && scalar @ips) {
 475         return bless \@ips, 'negated';
 476     } else {
 477         return \@ips;
 478     }
 479 }
 480
 481 # initialize stack: command line definitions
 482 unshift @stack, {};
 483
 484 # Get command line stuff
 485 if ($has_getopt) {
 486     my ($opt_noexec, $opt_flush, $opt_noflush, $opt_lines, $opt_interactive,
 487         $opt_timeout, $opt_help,
 488         $opt_version, $opt_test, $opt_fast, $opt_slow, $opt_shell,
 489         $opt_domain);
 490
 491     Getopt::Long::Configure('bundling', 'auto_help', 'no_ignore_case',
 492                             'no_auto_abbrev');
 493
 494     sub opt_def {
 495         my ($opt, $value) = @_;
 496         die 'Invalid --def specification'
 497           unless $value =~ /^\$?(\w+)=(.*)$/s;
 498         my ($name, $unparsed_value) = ($1, $2);
 499         my $tokens = tokenize_string($unparsed_value);
 500         $value = getvalues(sub { shift @$tokens; });
 501         die 'Extra tokens after --def'
 502           if @$tokens > 0;
 503         $stack[0]{vars}{$name} = $value;
 504     }
 505
 506     local $SIG{__WARN__} = sub { die $_[0]; };
 507     GetOptions('noexec|n' => \$opt_noexec,
 508                'flush|F' => \$opt_flush,
 509                'noflush' => \$opt_noflush,
 510                'lines|l' => \$opt_lines,
 511                'interactive|i' => \$opt_interactive,
 512                'timeout|t=s' => \$opt_timeout,
 513                'help|h' => \$opt_help,
 514                'version|V' => \$opt_version,
 515                test => \$opt_test,
 516                remote => \$opt_test,
 517                fast => \$opt_fast,
 518                slow => \$opt_slow,
 519                shell => \$opt_shell,
 520                'domain=s' => \$opt_domain,
 521                'def=s' => \&opt_def,
 522               );
 523
 524     if (defined $opt_help) {
 525         require Pod::Usage;
 526         Pod::Usage::pod2usage(-exitstatus => 0);
 527     }
 528
 529     if (defined $opt_version) {
 530         printversion();
 531         exit 0;
 532     };
 533
 534     $option{noexec} = $opt_noexec || $opt_test;
 535     $option{flush} = $opt_flush;
 536     $option{noflush} = $opt_noflush;
 537     $option{lines} = $opt_lines || $opt_test || $opt_shell;
 538     $option{interactive} = $opt_interactive && !$opt_noexec;
 539     $option{timeout} = defined $opt_timeout ? $opt_timeout : "30";
 540     $option{test} = $opt_test;
 541     $option{fast} = !$opt_slow;
 542     $option{shell} = $opt_shell;
 543
 544     die("ferm interactive mode not possible: /dev/stdin is not a tty\n")
 545       if $option{interactive} and not -t STDIN;
 546     die("ferm interactive mode not possible: /dev/stderr is not a tty\n")
 547       if $option{interactive} and not -t STDERR;
 548     die("ferm timeout has no sense without interactive mode")
 549         if not $opt_interactive and defined $opt_timeout;
 550     die("invalid timeout. must be an integer")
 551         if defined $opt_timeout and not $opt_timeout =~ /^[+-]?\d+$/;
 552
 553     $option{domain} = $opt_domain if defined $opt_domain;
 554 } else {
 555     # tiny getopt emulation for microperl
 556     my $filename;
 557     foreach (@ARGV) {
 558         if ($_ eq '--noexec' or $_ eq '-n') {
 559             $option{noexec} = 1;
 560         } elsif ($_ eq '--lines' or $_ eq '-l') {
 561             $option{lines} = 1;
 562         } elsif ($_ eq '--fast') {
 563             $option{fast} = 1;
 564         } elsif ($_ eq '--test') {
 565             $option{test} = 1;
 566             $option{noexec} = 1;
 567             $option{lines} = 1;
 568         } elsif ($_ eq '--shell') {
 569             $option{$_} = 1 foreach qw(shell fast lines);
 570         } elsif (/^-/) {
 571             printf STDERR "Usage: ferm [--noexec] [--lines] [--fast] [--shell] FILENAME\n";
 572             exit 1;
 573         } else {
 574             $filename = $_;
 575         }
 576     }
 577     undef @ARGV;
 578     push @ARGV, $filename;
 579 }
 580
 581 unless (@ARGV == 1) {
 582     require Pod::Usage;
 583     Pod::Usage::pod2usage(-exitstatus => 1);
 584 }
 585
 586 if ($has_strict) {
 587     open LINES, ">&STDOUT" if $option{lines};
 588     open STDOUT, ">&STDERR" if $option{shell};
 589 } else {
 590     # microperl can't redirect file handles
 591     *LINES = *STDOUT;
 592
 593     if ($option{fast} and not $option{noexec}) {
 594         print STDERR "Sorry, ferm on microperl does not allow --fast without --noexec\n";
 595         exit 1
 596     }
 597 }
 598
 599 unshift @stack, {};
 600 open_script($ARGV[0]);
 601
 602 my( $volume,$dirs,$file ) = File::Spec->splitpath( $ARGV[0] );
 603 $stack[0]{auto}{FILENAME} = $ARGV[0];
 604 $stack[0]{auto}{FILEBNAME} = $file;
 605 $stack[0]{auto}{DIRNAME} = $dirs;
 606
 607
 608
 609 # parse all input recursively
 610 enter(0, undef);
 611 die unless @stack == 2;
 612
 613 # enable/disable hooks depending on --flush
 614
 615 if ($option{flush}) {
 616     undef @pre_hooks;
 617     undef @post_hooks;
 618 } else {
 619     undef @flush_hooks;
 620 }
 621
 622 # execute all generated rules
 623 my $status;
 624
 625 foreach my $cmd (@pre_hooks) {
 626     print LINES "$cmd\n" if $option{lines};
 627     system($cmd) unless $option{noexec};
 628 }
 629
 630 while (my ($domain, $domain_info) = each %domains) {
 631     next unless $domain_info->{enabled};
 632     my $s = $option{fast} &&
 633       defined $domain_info->{tools}{'tables-restore'}
 634       ? execute_fast($domain_info) : execute_slow($domain_info);
 635     $status = $s if defined $s;
 636 }
 637
 638 foreach my $cmd (@post_hooks, @flush_hooks) {
 639     print LINES "$cmd\n" if $option{lines};
 640     system($cmd) unless $option{noexec};
 641 }
 642
 643 if (defined $status) {
 644     rollback();
 645     exit $status;
 646 }
 647
 648 # ask user, and rollback if there is no confirmation
 649
 650 if ($option{interactive}) {
 651     if ($option{shell}) {
 652         print LINES "echo 'ferm has applied the new firewall rules.'\n";
 653         print LINES "echo 'Please press Ctrl-C to confirm.'\n";
 654         print LINES "sleep $option{timeout}\n";
 655         while (my ($domain, $domain_info) = each %domains) {
 656             my $restore = $domain_info->{tools}{'tables-restore'};
 657             next unless defined $restore;
 658             print LINES "$restore <\$${domain}_tmp\n";
 659         }
 660     }
 661
 662     confirm_rules() or rollback() unless $option{noexec};
 663 }
 664
 665 exit 0;
 666
 667 # end of program execution!
 668
 669
 670 # funcs
 671
 672 sub printversion {
 673     print "ferm $VERSION\n";
 674     print "Copyright (C) 2001-2012 Max Kellermann, Auke Kok\n";
 675     print "This program is free software released under GPLv2.\n";
 676     print "See the included COPYING file for license details.\n";
 677 }
 678
 679
 680 sub error {
 681     # returns a nice formatted error message, showing the
 682     # location of the error.
 683     my $tabs = 0;
 684     my @lines;
 685     my $l = 0;
 686     my @words = map { @$_ } @{$script->{past_tokens}};
 687
 688     for my $w ( 0 .. $#words ) {
 689         if ($words[$w] eq "\x29")
 690             { $l++ ; $lines[$l] = "    " x ($tabs-- -1) ;};
 691         if ($words[$w] eq "\x28")
 692             { $l++ ; $lines[$l] = "    " x $tabs++ ;};
 693         if ($words[$w] eq "\x7d")
 694             { $l++ ; $lines[$l] = "    " x ($tabs-- -1) ;};
 695         if ($words[$w] eq "\x7b")
 696             { $l++ ; $lines[$l] = "    " x $tabs++ ;};
 697         if ( $l > $#lines ) { $lines[$l] = "" };
 698         $lines[$l] .= $words[$w] . " ";
 699         if ($words[$w] eq "\x28")
 700             { $l++ ; $lines[$l] = "    " x $tabs ;};
 701         if (($words[$w] eq "\x29") && ($words[$w+1] ne "\x7b"))
 702             { $l++ ; $lines[$l] = "    " x $tabs ;};
 703         if ($words[$w] eq "\x7b")
 704             { $l++ ; $lines[$l] = "    " x $tabs ;};
 705         if (($words[$w] eq "\x7d") && ($words[$w+1] ne "\x7d"))
 706             { $l++ ; $lines[$l] = "    " x $tabs ;};
 707         if (($words[$w] eq "\x3b") && ($words[$w+1] ne "\x7d"))
 708             { $l++ ; $lines[$l] = "    " x $tabs ;}
 709         if ($words[$w-1] eq "option")
 710             { $l++ ; $lines[$l] = "    " x $tabs ;}
 711     }
 712     my $start = $#lines - 4;
 713     if ($start < 0) { $start = 0 } ;
 714     print STDERR "Error in $script->{filename} line $script->{line}:\n";
 715     for $l ( $start .. $#lines)
 716         { print STDERR $lines[$l]; if ($l != $#lines ) {print STDERR "\n"} ; };
 717     print STDERR "<--\n";
 718     die("@_\n");
 719 }
 720
 721 # print a warning message about code from an input file
 722 sub warning {
 723     print STDERR "Warning in $script->{filename} line $script->{line}: "
 724       . (shift) . "\n";
 725 }
 726
 727 sub find_tool($) {
 728     my $name = shift;
 729     return $name if $option{test};
 730     for my $path ('/sbin', split ':', $ENV{PATH}) {
 731         my $ret = "$path/$name";
 732         return $ret if -x $ret;
 733     }
 734     die "$name not found in PATH\n";
 735 }
 736
 737 sub initialize_domain {
 738     my $domain = shift;
 739     my $domain_info = $domains{$domain} ||= {};
 740
 741     return if exists $domain_info->{initialized};
 742
 743     die "Invalid domain '$domain'\n" unless $domain =~ /^(?:ip6?|arp|eb)$/;
 744
 745     my @tools = qw(tables);
 746     push @tools, qw(tables-save tables-restore)
 747       if $domain =~ /^ip6?$/;
 748
 749     # determine the location of this domain's tools
 750     my %tools = map { $_ => find_tool($domain . $_) } @tools;
 751     $domain_info->{tools} = \%tools;
 752
 753     # make tables-save tell us about the state of this domain
 754     # (which tables and chains do exist?), also remember the old
 755     # save data which may be used later by the rollback function
 756     local *SAVE;
 757     if (!$option{test} &&
 758         exists $tools{'tables-save'} &&
 759         open(SAVE, "$tools{'tables-save'}|")) {
 760         my $save = '';
 761
 762         my $table_info;
 763         while (<SAVE>) {
 764             $save .= $_;
 765
 766             if (/^\*(\w+)/) {
 767                 my $table = $1;
 768                 $table_info = $domain_info->{tables}{$table} ||= {};
 769             } elsif (defined $table_info and /^:(\w+)\s+(\S+)/
 770                      and $2 ne '-') {
 771                 $table_info->{chains}{$1}{builtin} = 1;
 772                 $table_info->{has_builtin} = 1;
 773             }
 774         }
 775
 776         # for rollback
 777         $domain_info->{previous} = $save;
 778     }
 779
 780     if ($option{shell} && $option{interactive} &&
 781           exists $tools{'tables-save'}) {
 782         print LINES "${domain}_tmp=\$(mktemp ferm.XXXXXXXXXX)\n";
 783         print LINES "$tools{'tables-save'} >\$${domain}_tmp\n";
 784     }
 785
 786     $domain_info->{initialized} = 1;
 787 }
 788
 789 sub check_domain($) {
 790     my $domain = shift;
 791     my @result;
 792
 793     return if exists $option{domain}
 794       and $domain ne $option{domain};
 795
 796     eval {
 797         initialize_domain($domain);
 798     };
 799     error($@) if $@;
 800
 801     return 1;
 802 }
 803
 804 # split the input string into words and delete comments
 805 sub tokenize_string($) {
 806     my $string = shift;
 807
 808     my @ret;
 809
 810     foreach my $word ($string =~ m/(".*?"|'.*?'|`.*?`|[!,=&\$\%\(\){};]|[-+\w\/\.:]+|@\w+|#)/g) {
 811         last if $word eq '#';
 812         push @ret, $word;
 813     }
 814
 815     return \@ret;
 816 }
 817
 818 # generate a "line" special token, that marks the line number; these
 819 # special tokens are inserted after each line break, so ferm keeps
 820 # track of line numbers
 821 sub make_line_token($) {
 822     my $line = shift;
 823     return bless(\$line, 'line');
 824 }
 825
 826 # read some more tokens from the input file into a buffer
 827 sub prepare_tokens() {
 828     my $tokens = $script->{tokens};
 829     while (@$tokens == 0) {
 830         my $handle = $script->{handle};
 831         return unless defined $handle;
 832         my $line = <$handle>;
 833         return unless defined $line;
 834
 835         push @$tokens, make_line_token($script->{line} + 1);
 836
 837         # the next parser stage eats this
 838         push @$tokens, @{tokenize_string($line)};
 839     }
 840
 841     return 1;
 842 }
 843
 844 sub handle_special_token($) {
 845     my $token = shift;
 846     die unless ref $token;
 847     if (ref $token eq 'line') {
 848         $script->{line} = $$token;
 849     } else {
 850         die;
 851     }
 852 }
 853
 854 sub handle_special_tokens() {
 855     my $tokens = $script->{tokens};
 856     while (@$tokens > 0 and ref $tokens->[0]) {
 857         handle_special_token(shift @$tokens);
 858     }
 859 }
 860
 861 # wrapper for prepare_tokens() which handles "special" tokens
 862 sub prepare_normal_tokens() {
 863     my $tokens = $script->{tokens};
 864     while (1) {
 865         handle_special_tokens();
 866         return 1 if @$tokens > 0;
 867         return unless prepare_tokens();
 868     }
 869 }
 870
 871 # open a ferm sub script
 872 sub open_script($) {
 873     my $filename = shift;
 874
 875     for (my $s = $script; defined $s; $s = $s->{parent}) {
 876         die("Circular reference in $script->{filename} line $script->{line}: $filename\n")
 877           if $s->{filename} eq $filename;
 878     }
 879
 880     my $handle;
 881     if ($filename eq '-') {
 882         # Note that this only allowed in the command-line argument and not
 883         # @includes, since those are filtered by collect_filenames()
 884         $handle = *STDIN;
 885         # also set a filename label so that error messages are more helpful
 886         $filename = "<stdin>";
 887     } else {
 888         local *FILE;
 889         open FILE, "$filename" or die("Failed to open $filename: $!\n");
 890         $handle = *FILE;
 891     }
 892
 893     $script = { filename => $filename,
 894                 handle => $handle,
 895                 line => 0,
 896                 past_tokens => [],
 897                 tokens => [],
 898                 parent => $script,
 899               };
 900
 901     return $script;
 902 }
 903
 904 # collect script filenames which are being included
 905 sub collect_filenames(@) {
 906     my @ret;
 907
 908     # determine the current script's parent directory for relative
 909     # file names
 910     die unless defined $script;
 911     my $parent_dir = $script->{filename} =~ m,^(.*/),
 912       ? $1 : './';
 913
 914     foreach my $pathname (@_) {
 915         # non-absolute file names are relative to the parent script's
 916         # file name
 917         $pathname = $parent_dir . $pathname
 918           unless $pathname =~ m,^/|\|$,;
 919
 920         if ($pathname =~ m,/$,) {
 921             # include all regular files in a directory
 922
 923             error("'$pathname' is not a directory")
 924               unless -d $pathname;
 925
 926             local *DIR;
 927             opendir DIR, $pathname
 928               or error("Failed to open directory '$pathname': $!");
 929             my @names = readdir DIR;
 930             closedir DIR;
 931
 932             # sort those names for a well-defined order
 933             foreach my $name (sort { $a cmp $b } @names) {
 934                 # ignore dpkg's backup files
 935                 next if $name =~ /\.dpkg-(old|dist|new|tmp)$/;
 936                 # don't include hidden and backup files
 937                 next if $name =~ /^\.|~$/;
 938
 939                 my $filename = $pathname . $name;
 940                 push @ret, $filename
 941                   if -f $filename;
 942             }
 943         } elsif ($pathname =~ m,\|$,) {
 944             # run a program and use its output
 945             push @ret, $pathname;
 946         } elsif ($pathname =~ m,^\|,) {
 947             error('This kind of pipe is not allowed');
 948         } else {
 949             # include a regular file
 950
 951             error("'$pathname' is a directory; maybe use trailing '/' to include a directory?")
 952               if -d $pathname;
 953             error("'$pathname' is not a file")
 954               unless -f $pathname;
 955
 956             push @ret, $pathname;
 957         }
 958     }
 959
 960     return @ret;
 961 }
 962
 963 # peek a token from the queue, but don't remove it
 964 sub peek_token() {
 965     return unless prepare_normal_tokens();
 966     return $script->{tokens}[0];
 967 }
 968
 969 # get a token from the queue, including "special" tokens
 970 sub next_raw_token() {
 971     return unless prepare_tokens();
 972     return shift @{$script->{tokens}};
 973 }
 974
 975 # get a token from the queue
 976 sub next_token() {
 977     return unless prepare_normal_tokens();
 978     my $token = shift @{$script->{tokens}};
 979
 980     # update $script->{past_tokens}
 981     my $past_tokens = $script->{past_tokens};
 982
 983     if (@$past_tokens > 0) {
 984         my $prev_token = $past_tokens->[-1][-1];
 985         $past_tokens->[-1] = @$past_tokens > 1 ? ['{'] : []
 986           if $prev_token eq ';';
 987         if ($prev_token eq '}') {
 988             pop @$past_tokens;
 989             $past_tokens->[-1] = $past_tokens->[-1][0] eq '{'
 990               ? [ '{' ] : []
 991                 if @$past_tokens > 0;
 992         }
 993     }
 994
 995     push @$past_tokens, [] if $token eq '{' or @$past_tokens == 0;
 996     push @{$past_tokens->[-1]}, $token;
 997
 998     # return
 999     return $token;
1000 }
1001
1002 sub expect_token($;$) {
1003     my $expect = shift;
1004     my $msg = shift;
1005     my $token = next_token();
1006     error($msg || "'$expect' expected")
1007       unless defined $token and $token eq $expect;
1008 }
1009
1010 # require that another token exists, and that it's not a "special"
1011 # token, e.g. ";" and "{"
1012 sub require_next_token {
1013     my $code = shift || \&next_token;
1014
1015     my $token = &$code(@_);
1016
1017     error('unexpected end of file')
1018       unless defined $token;
1019
1020     error("'$token' not allowed here")
1021       if $token =~ /^[;{}]$/;
1022
1023     return $token;
1024 }
1025
1026 # return the value of a variable
1027 sub variable_value($) {
1028     my $name = shift;
1029
1030     if ($name eq "LINE") {
1031         return $script->{line};
1032     }
1033
1034     foreach (@stack) {
1035         return $_->{vars}{$name}
1036           if exists $_->{vars}{$name};
1037     }
1038
1039     return $stack[0]{auto}{$name}
1040       if exists $stack[0]{auto}{$name};
1041
1042     return;
1043 }
1044
1045 # determine the value of a variable, die if the value is an array
1046 sub string_variable_value($) {
1047     my $name = shift;
1048     my $value = variable_value($name);
1049
1050     error("variable '$name' must be a string, but it is an array")
1051       if ref $value;
1052
1053     return $value;
1054 }
1055
1056 # similar to the built-in "join" function, but also handle negated
1057 # values in a special way
1058 sub join_value($$) {
1059     my ($expr, $value) = @_;
1060
1061     unless (ref $value) {
1062         return $value;
1063     } elsif (ref $value eq 'ARRAY') {
1064         return join($expr, @$value);
1065     } elsif (ref $value eq 'negated') {
1066         # bless'negated' is a special marker for negated values
1067         $value = join_value($expr, $value->[0]);
1068         return bless [ $value ], 'negated';
1069     } else {
1070         die;
1071     }
1072 }
1073
1074 sub negate_value($$;$) {
1075     my ($value, $class, $allow_array) = @_;
1076
1077     if (ref $value) {
1078         error('double negation is not allowed')
1079           if ref $value eq 'negated' or ref $value eq 'pre_negated';
1080
1081         error('it is not possible to negate an array')
1082           if ref $value eq 'ARRAY' and not $allow_array;
1083     }
1084
1085     return bless [ $value ], $class || 'negated';
1086 }
1087
1088 sub format_bool($) {
1089     return $_[0] ? 1 : 0;
1090 }
1091
1092 sub resolve($\@$) {
1093     my ($resolver, $names, $type) = @_;
1094
1095     my @result;
1096     foreach my $hostname (@$names) {
1097         my $query = $resolver->search($hostname, $type);
1098         error("DNS query for '$hostname' failed: " . $resolver->errorstring)
1099           unless $query;
1100
1101         foreach my $rr ($query->answer) {
1102             next unless $rr->type eq $type;
1103
1104             if ($type eq 'NS') {
1105                 push @result, $rr->nsdname;
1106             } elsif ($type eq 'MX') {
1107                 push @result, $rr->exchange;
1108             } else {
1109                 push @result, $rr->address;
1110             }
1111         }
1112     }
1113
1114     # NS/MX records return host names; resolve these again in the
1115     # second pass (IPv4 only currently)
1116     @result = resolve($resolver, @result, 'A')
1117       if $type eq 'NS' or $type eq 'MX';
1118
1119     return @result;
1120 }
1121
1122 sub lookup_function($) {
1123     my $name = shift;
1124
1125     foreach (@stack) {
1126         return $_->{functions}{$name}
1127           if exists $_->{functions}{$name};
1128     }
1129
1130     return;
1131 }
1132
1133 # returns the next parameter, which may either be a scalar or an array
1134 sub getvalues {
1135     my $code = shift;
1136     my %options = @_;
1137
1138     my $token = require_next_token($code);
1139
1140     if ($token eq '(') {
1141         # read an array until ")"
1142         my @wordlist;
1143
1144         for (;;) {
1145             $token = getvalues($code,
1146                                parenthesis_allowed => 1,
1147                                comma_allowed => 1);
1148
1149             unless (ref $token) {
1150                 last if $token eq ')';
1151
1152                 if ($token eq ',') {
1153                     error('Comma is not allowed within arrays, please use only a space');
1154                     next;
1155                 }
1156
1157                 push @wordlist, $token;
1158             } elsif (ref $token eq 'ARRAY') {
1159                 push @wordlist, @$token;
1160             } else {
1161                 error('unknown toke type');
1162             }
1163         }
1164
1165         error('empty array not allowed here')
1166           unless @wordlist or not $options{non_empty};
1167
1168         return @wordlist == 1
1169           ? $wordlist[0]
1170             : \@wordlist;
1171     } elsif ($token =~ /^\`(.*)\`$/s) {
1172         # execute a shell command, insert output
1173         my $command = $1;
1174         my $output = `$command`;
1175         unless ($? == 0) {
1176             if ($? == -1) {
1177                 error("failed to execute: $!");
1178             } elsif ($? & 0x7f) {
1179                 error("child died with signal " . ($? & 0x7f));
1180             } elsif ($? >> 8) {
1181                 error("child exited with status " . ($? >> 8));
1182             }
1183         }
1184
1185         # remove comments
1186         $output =~ s/#.*//mg;
1187
1188         # tokenize
1189         my @tokens = grep { length } split /\s+/s, $output;
1190
1191         my @values;
1192         while (@tokens) {
1193             my $value = getvalues(sub { shift @tokens });
1194             push @values, to_array($value);
1195         }
1196
1197         # and recurse
1198         return @values == 1
1199           ? $values[0]
1200             : \@values;
1201     } elsif ($token =~ /^\'(.*)\'$/s) {
1202         # single quotes: a string
1203         return $1;
1204     } elsif ($token =~ /^\"(.*)\"$/s) {
1205         # double quotes: a string with escapes
1206         $token = $1;
1207         $token =~ s,\$(\w+),string_variable_value($1),eg;
1208         return $token;
1209     } elsif ($token eq '!') {
1210         error('negation is not allowed here')
1211           unless $options{allow_negation};
1212
1213         $token = getvalues($code);
1214
1215         return negate_value($token, undef, $options{allow_array_negation});
1216     } elsif ($token eq ',') {
1217         return $token
1218           if $options{comma_allowed};
1219
1220         error('comma is not allowed here');
1221     } elsif ($token eq '=') {
1222         error('equals operator ("=") is not allowed here');
1223     } elsif ($token eq '$') {
1224         my $name = require_next_token($code);
1225         error('variable name expected - if you want to concatenate strings, try using double quotes')
1226           unless $name =~ /^\w+$/;
1227
1228         my $value = variable_value($name);
1229
1230         error("no such variable: \$$name")
1231           unless defined $value;
1232
1233         return $value;
1234     } elsif ($token eq '&') {
1235         error("function calls are not allowed as keyword parameter");
1236     } elsif ($token eq ')' and not $options{parenthesis_allowed}) {
1237         error('Syntax error');
1238     } elsif ($token =~ /^@/) {
1239         if ($token eq '@resolve') {
1240             my @params = get_function_params();
1241             error('Usage: @resolve((hostname ...), [type])')
1242               unless @params == 1 or @params == 2;
1243             eval { require Net::DNS; };
1244             error('For the @resolve() function, you need the Perl library Net::DNS')
1245               if $@;
1246             my $type = $params[1] || 'A';
1247             error('String expected') if ref $type;
1248             my $resolver = new Net::DNS::Resolver;
1249             @params = to_array($params[0]);
1250             my @result = resolve($resolver, @params, $type);
1251             return @result == 1 ? $result[0] : \@result;
1252         } elsif ($token eq '@defined') {
1253             expect_token('(', 'function name must be followed by "()"');
1254             my $type = require_next_token();
1255             if ($type eq '$') {
1256                 my $name = require_next_token();
1257                 error('variable name expected')
1258                   unless $name =~ /^\w+$/;
1259                 expect_token(')');
1260                 return defined variable_value($name);
1261             } elsif ($type eq '&') {
1262                 my $name = require_next_token();
1263                 error('function name expected')
1264                   unless $name =~ /^\w+$/;
1265                 expect_token(')');
1266                 return defined lookup_function($name);
1267             } else {
1268                 error("'\$' or '&' expected")
1269             }
1270         } elsif ($token eq '@eq') {
1271             my @params = get_function_params();
1272             error('Usage: @eq(a, b)') unless @params == 2;
1273             return format_bool($params[0] eq $params[1]);
1274         } elsif ($token eq '@ne') {
1275             my @params = get_function_params();
1276             error('Usage: @ne(a, b)') unless @params == 2;
1277             return format_bool($params[0] ne $params[1]);
1278         } elsif ($token eq '@not') {
1279             my @params = get_function_params();
1280             error('Usage: @not(a)') unless @params == 1;
1281             return format_bool(not $params[0]);
1282         } elsif ($token eq '@cat') {
1283             my $value = '';
1284             map {
1285                 error('String expected') if ref $_;
1286                 $value .= $_;
1287             } get_function_params();
1288             return $value;
1289         } elsif ($token eq '@substr') {
1290             my @params = get_function_params();
1291             error('Usage: @substr(string, num, num)') unless @params == 3;
1292             error('String expected') if ref $params[0] or ref $params[1] or ref $params[2];
1293             return substr($params[0],$params[1],$params[2]);
1294         } elsif ($token eq '@length') {
1295             my @params = get_function_params();
1296             error('Usage: @length(string)') unless @params == 1;
1297             error('String expected') if ref $params[0];
1298             return length($params[0]);
1299         } elsif ($token eq '@basename') {
1300             my @params = get_function_params();
1301             error('Usage: @basename(path)') unless @params == 1;
1302             error('String expected') if ref $params[0];
1303             my($volume,$path,$file) = File::Spec->splitpath( $params[0] );
1304             return $file;
1305         } elsif ($token eq '@dirname') {
1306             my @params = get_function_params();
1307             error('Usage: @dirname(path)') unless @params == 1;
1308             error('String expected') if ref $params[0];
1309             my($volume,$path,$file) = File::Spec->splitpath( $params[0] );
1310             return $path;
1311         } elsif ($token eq '@ipfilter') {
1312             my @params = get_function_params();
1313             error('Usage: @ipfilter((ip1 ip2 ...))') unless @params == 1;
1314             my $domain = $stack[0]{auto}{DOMAIN};
1315             error('No domain specified') unless defined $domain;
1316             my @ips = ipfilter($domain, to_array($params[0]));
1317             return \@ips;
1318         } else {
1319             error("unknown ferm built-in function");
1320         }
1321     } else {
1322         return $token;
1323     }
1324 }
1325
1326 # returns the next parameter, but only allow a scalar
1327 sub getvar() {
1328     my $token = getvalues();
1329
1330     error('array not allowed here')
1331       if ref $token and ref $token eq 'ARRAY';
1332
1333     return $token;
1334 }
1335
1336 sub get_function_params(%) {
1337     expect_token('(', 'function name must be followed by "()"');
1338
1339     my $token = peek_token();
1340     if ($token eq ')') {
1341         require_next_token();
1342         return;
1343     }
1344
1345     my @params;
1346
1347     while (1) {
1348         if (@params > 0) {
1349             $token = require_next_token();
1350             last
1351               if $token eq ')';
1352
1353             error('"," expected')
1354               unless $token eq ',';
1355         }
1356
1357         push @params, getvalues(undef, @_);
1358     }
1359
1360     return @params;
1361 }
1362
1363 # collect all tokens in a flat array reference until the end of the
1364 # command is reached
1365 sub collect_tokens {
1366     my %options = @_;
1367
1368     my @level;
1369     my @tokens;
1370
1371     # re-insert a "line" token, because the starting token of the
1372     # current line has been consumed already
1373     push @tokens, make_line_token($script->{line});
1374
1375     while (1) {
1376         my $keyword = next_raw_token();
1377         error('unexpected end of file within function/variable declaration')
1378           unless defined $keyword;
1379
1380         if (ref $keyword) {
1381             handle_special_token($keyword);
1382         } elsif ($keyword =~ /^[\{\(]$/) {
1383             push @level, $keyword;
1384         } elsif ($keyword =~ /^[\}\)]$/) {
1385             my $expected = $keyword;
1386             $expected =~ tr/\}\)/\{\(/;
1387             my $opener = pop @level;
1388             error("unmatched '$keyword'")
1389               unless defined $opener and $opener eq $expected;
1390         } elsif ($keyword eq ';' and @level == 0) {
1391             push @tokens, $keyword
1392               if $options{include_semicolon};
1393
1394             if ($options{include_else}) {
1395                 my $token = peek_token;
1396                 next if $token eq '@else';
1397             }
1398
1399             last;
1400         }
1401
1402         push @tokens, $keyword;
1403
1404         last
1405           if $keyword eq '}' and @level == 0;
1406     }
1407
1408     return \@tokens;
1409 }
1410
1411
1412 # returns the specified value as an array. dereference arrayrefs
1413 sub to_array($) {
1414     my $value = shift;
1415     die unless wantarray;
1416     die if @_;
1417     unless (ref $value) {
1418         return $value;
1419     } elsif (ref $value eq 'ARRAY') {
1420         return @$value;
1421     } else {
1422         die;
1423     }
1424 }
1425
1426 # evaluate the specified value as bool
1427 sub eval_bool($) {
1428     my $value = shift;
1429     die if wantarray;
1430     die if @_;
1431     unless (ref $value) {
1432         return $value;
1433     } elsif (ref $value eq 'ARRAY') {
1434         return @$value > 0;
1435     } else {
1436         die;
1437     }
1438 }
1439
1440 sub is_netfilter_core_target($) {
1441     my $target = shift;
1442     die unless defined $target and length $target;
1443     return grep { $_ eq $target } qw(ACCEPT DROP RETURN QUEUE);
1444 }
1445
1446 sub is_netfilter_module_target($$) {
1447     my ($domain_family, $target) = @_;
1448     die unless defined $target and length $target;
1449
1450     return defined $domain_family &&
1451       exists $target_defs{$domain_family} &&
1452         $target_defs{$domain_family}{$target};
1453 }
1454
1455 sub is_netfilter_builtin_chain($$) {
1456     my ($table, $chain) = @_;
1457
1458     return grep { $_ eq $chain }
1459       qw(PREROUTING INPUT FORWARD OUTPUT POSTROUTING);
1460 }
1461
1462 sub netfilter_canonical_protocol($) {
1463     my $proto = shift;
1464     return 'icmp'
1465       if $proto eq 'ipv6-icmp' or $proto eq 'icmpv6';
1466     return 'mh'
1467       if $proto eq 'ipv6-mh';
1468     return $proto;
1469 }
1470
1471 sub netfilter_protocol_module($) {
1472     my $proto = shift;
1473     return unless defined $proto;
1474     return 'icmp6'
1475       if $proto eq 'icmpv6';
1476     return $proto;
1477 }
1478
1479 # escape the string in a way safe for the shell
1480 sub shell_escape($) {
1481     my $token = shift;
1482
1483     return $token if $token =~ /^[-_a-zA-Z0-9]+$/s;
1484
1485     if ($option{fast}) {
1486         # iptables-save/iptables-restore are quite buggy concerning
1487         # escaping and special characters... we're trying our best
1488         # here
1489
1490         $token =~ s,",\\",g;
1491         $token = '"' . $token . '"'
1492           if $token =~ /[\s\'\\;&]/s or length($token) == 0;
1493     } else {
1494         return $token
1495           if $token =~ /^\`.*\`$/;
1496         $token =~ s/'/'\\''/g;
1497         $token = '\'' . $token . '\''
1498           if $token =~ /[\s\"\\;<>&|]/s or length($token) == 0;
1499     }
1500
1501     return $token;
1502 }
1503
1504 # append an option to the shell command line, using information from
1505 # the module definition (see %match_defs etc.)
1506 sub shell_format_option($$) {
1507     my ($keyword, $value) = @_;
1508
1509     my $cmd = '';
1510     if (ref $value) {
1511         if ((ref $value eq 'negated') || (ref $value eq 'pre_negated')) {
1512             $value = $value->[0];
1513             $cmd = ' !';
1514         }
1515     }
1516
1517     unless (defined $value) {
1518         $cmd .= " --$keyword";
1519     } elsif (ref $value) {
1520         if (ref $value eq 'params') {
1521             $cmd .= " --$keyword ";
1522             $cmd .= join(' ', map { shell_escape($_) } @$value);
1523         } elsif (ref $value eq 'multi') {
1524             foreach (@$value) {
1525                 $cmd .= " --$keyword " . shell_escape($_);
1526             }
1527         } else {
1528             die;
1529         }
1530     } else {
1531         $cmd .= " --$keyword " . shell_escape($value);
1532     }
1533
1534     return $cmd;
1535 }
1536
1537 sub format_option($$$) {
1538     my ($domain, $name, $value) = @_;
1539
1540     $value = 'icmpv6' if $domain eq 'ip6' and $name eq 'protocol'
1541       and $value eq 'icmp';
1542     $name = 'icmpv6-type' if $domain eq 'ip6' and $name eq 'icmp-type';
1543
1544     if ($domain eq 'ip6' and $name eq 'reject-with') {
1545         my %icmp_map = (
1546             'icmp-net-unreachable'  => 'icmp6-no-route',
1547             'icmp-host-unreachable' => 'icmp6-addr-unreachable',
1548             'icmp-port-unreachable' => 'icmp6-port-unreachable',
1549             'icmp-net-prohibited'   => 'icmp6-adm-prohibited',
1550             'icmp-host-prohibited'  => 'icmp6-adm-prohibited',
1551             'icmp-admin-prohibited' => 'icmp6-adm-prohibited',
1552         );
1553         $value = $icmp_map{$value} if exists $icmp_map{$value};
1554     }
1555
1556     return shell_format_option($name, $value);
1557 }
1558
1559 sub append_rule($$) {
1560     my ($chain_rules, $rule) = @_;
1561
1562     my $cmd = join('', map { $_->[2] } @{$rule->{options}});
1563     push @$chain_rules, { rule => $cmd,
1564                           script => $rule->{script},
1565                         };
1566 }
1567
1568 sub unfold_rule {
1569     my ($domain, $chain_rules, $rule) = (shift, shift, shift);
1570     return append_rule($chain_rules, $rule) unless @_;
1571
1572     my $option = shift;
1573     my @values = @{$option->[1]};
1574
1575     foreach my $value (@values) {
1576         $option->[2] = format_option($domain, $option->[0], $value);
1577         unfold_rule($domain, $chain_rules, $rule, @_);
1578     }
1579 }
1580
1581 sub mkrules2($$$) {
1582     my ($domain, $chain_rules, $rule) = @_;
1583
1584     my @unfold;
1585     foreach my $option (@{$rule->{options}}) {
1586         if (ref $option->[1] and ref $option->[1] eq 'ARRAY') {
1587             push @unfold, $option
1588         } else {
1589             $option->[2] = format_option($domain, $option->[0], $option->[1]);
1590         }
1591     }
1592
1593     unfold_rule($domain, $chain_rules, $rule, @unfold);
1594 }
1595
1596 # convert a bunch of internal rule structures in iptables calls,
1597 # unfold arrays during that
1598 sub mkrules($) {
1599     my $rule = shift;
1600
1601     my $domain = $rule->{domain};
1602     my $domain_info = $domains{$domain};
1603     $domain_info->{enabled} = 1;
1604
1605     foreach my $table (to_array $rule->{table}) {
1606         my $table_info = $domain_info->{tables}{$table} ||= {};
1607
1608         foreach my $chain (to_array $rule->{chain}) {
1609             my $chain_rules = $table_info->{chains}{$chain}{rules} ||= [];
1610             mkrules2($domain, $chain_rules, $rule)
1611               if $rule->{has_rule} and not $option{flush};
1612         }
1613     }
1614 }
1615
1616 # parse a keyword from a module definition
1617 sub parse_keyword(\%$$) {
1618     my ($rule, $def, $negated_ref) = @_;
1619
1620     my $params = $def->{params};
1621
1622     my $value;
1623
1624     my $negated;
1625     if ($$negated_ref && exists $def->{pre_negation}) {
1626         $negated = 1;
1627         undef $$negated_ref;
1628     }
1629
1630     unless (defined $params) {
1631         undef $value;
1632     } elsif (ref $params && ref $params eq 'CODE') {
1633         $value = &$params($rule);
1634     } elsif ($params eq 'm') {
1635         $value = bless [ to_array getvalues() ], 'multi';
1636     } elsif ($params =~ /^[a-z]/) {
1637         if (exists $def->{negation} and not $negated) {
1638             my $token = peek_token();
1639             if ($token eq '!') {
1640                 require_next_token();
1641                 $negated = 1;
1642             }
1643         }
1644
1645         my @params;
1646         foreach my $p (split(//, $params)) {
1647             if ($p eq 's') {
1648                 push @params, getvar();
1649             } elsif ($p eq 'c') {
1650                 my @v = to_array getvalues(undef, non_empty => 1);
1651                 push @params, join(',', @v);
1652             } else {
1653                 die;
1654             }
1655         }
1656
1657         $value = @params == 1
1658           ? $params[0]
1659             : bless \@params, 'params';
1660     } elsif ($params == 1) {
1661         if (exists $def->{negation} and not $negated) {
1662             my $token = peek_token();
1663             if ($token eq '!') {
1664                 require_next_token();
1665                 $negated = 1;
1666             }
1667         }
1668
1669         $value = getvalues();
1670
1671         warning("log-prefix is too long; truncating to 29 characters: '$1'")
1672           if $def->{name} eq 'log-prefix' && $value =~ s,^(.{29}).+$,$1,;
1673     } else {
1674         if (exists $def->{negation} and not $negated) {
1675             my $token = peek_token();
1676             if ($token eq '!') {
1677                 require_next_token();
1678                 $negated = 1;
1679             }
1680         }
1681
1682         $value = bless [ map {
1683             getvar()
1684         } (1..$params) ], 'params';
1685     }
1686
1687     $value = negate_value($value, exists $def->{pre_negation} && 'pre_negated')
1688       if $negated;
1689
1690     return $value;
1691 }
1692
1693 sub append_option(\%$$) {
1694     my ($rule, $name, $value) = @_;
1695     push @{$rule->{options}}, [ $name, $value ];
1696 }
1697
1698 # parse options of a module
1699 sub parse_option($\%$) {
1700     my ($def, $rule, $negated_ref) = @_;
1701
1702     append_option(%$rule, $def->{name},
1703                   parse_keyword(%$rule, $def, $negated_ref));
1704 }
1705
1706 sub copy_on_write($$) {
1707     my ($rule, $key) = @_;
1708     return unless exists $rule->{cow}{$key};
1709     $rule->{$key} = {%{$rule->{$key}}};
1710     delete $rule->{cow}{$key};
1711 }
1712
1713 sub new_level(\%$) {
1714     my ($rule, $prev) = @_;
1715
1716     %$rule = ();
1717     if (defined $prev) {
1718         # copy data from previous level
1719         $rule->{cow} = { keywords => 1, };
1720         $rule->{keywords} = $prev->{keywords};
1721         $rule->{match} = { %{$prev->{match}} };
1722         $rule->{options} = [@{$prev->{options}}];
1723         foreach my $key (qw(domain domain_family domain_both table chain protocol has_rule has_action)) {
1724             $rule->{$key} = $prev->{$key}
1725               if exists $prev->{$key};
1726         }
1727     } else {
1728         $rule->{cow} = {};
1729         $rule->{keywords} = {};
1730         $rule->{match} = {};
1731         $rule->{options} = [];
1732     }
1733 }
1734
1735 sub merge_keywords(\%$) {
1736     my ($rule, $keywords) = @_;
1737     copy_on_write($rule, 'keywords');
1738     while (my ($name, $def) = each %$keywords) {
1739         $rule->{keywords}{$name} = $def;
1740     }
1741 }
1742
1743 sub set_domain(\%$) {
1744     my ($rule, $domain) = @_;
1745
1746     return unless check_domain($domain);
1747
1748     my $domain_family;
1749     unless (ref $domain) {
1750         $domain_family = $domain eq 'ip6' ? 'ip' : $domain;
1751     } elsif (@$domain == 0) {
1752         $domain_family = 'none';
1753     } elsif (grep { not /^ip6?$/s } @$domain) {
1754         error('Cannot combine non-IP domains');
1755     } else {
1756         $domain_family = 'ip';
1757     }
1758
1759     $rule->{domain_family} = $domain_family;
1760     $rule->{keywords} = $match_defs{$domain_family}{''}{keywords};
1761     $rule->{cow}{keywords} = 1;
1762
1763     $rule->{domain} = $stack[0]{auto}{DOMAIN} = $domain;
1764 }
1765
1766 sub set_target(\%$$) {
1767     my ($rule, $name, $value) = @_;
1768     error('There can only one action per rule')
1769       if exists $rule->{has_action};
1770     $rule->{has_action} = 1;
1771     append_option(%$rule, $name, $value);
1772 }
1773
1774 sub set_module_target(\%$$) {
1775     my ($rule, $name, $defs) = @_;
1776
1777     if ($name eq 'TCPMSS') {
1778         my $protos = $rule->{protocol};
1779         error('No protocol specified before TCPMSS')
1780           unless defined $protos;
1781         foreach my $proto (to_array $protos) {
1782             error('TCPMSS not available for protocol "$proto"')
1783               unless $proto eq 'tcp';
1784         }
1785     }
1786
1787     # in ebtables, there is both "--mark" and "-j mark"... workaround:
1788     $name = 'mark' if $name eq 'MARK' and $rule->{domain_family} eq 'eb';
1789
1790     set_target(%$rule, 'jump', $name);
1791     merge_keywords(%$rule, $defs->{keywords});
1792 }
1793
1794 # the main parser loop: read tokens, convert them into internal rule
1795 # structures
1796 sub enter($$) {
1797     my $lev = shift;  # current recursion depth
1798     my $prev = shift; # previous rule hash
1799
1800     # enter is the core of the firewall setup, it is a
1801     # simple parser program that recognizes keywords and
1802     # retreives parameters to set up the kernel routing
1803     # chains
1804
1805     my $base_level = $script->{base_level} || 0;
1806     die if $base_level > $lev;
1807
1808     my %rule;
1809     new_level(%rule, $prev);
1810
1811     # read keywords 1 by 1 and dump into parser
1812     while (defined (my $keyword = next_token())) {
1813         # check if the current rule should be negated
1814         my $negated = $keyword eq '!';
1815         if ($negated) {
1816             # negation. get the next word which contains the 'real'
1817             # rule
1818             $keyword = getvar();
1819
1820             error('unexpected end of file after negation')
1821               unless defined $keyword;
1822         }
1823
1824         # the core: parse all data
1825         for ($keyword)
1826         {
1827             # deprecated keyword?
1828             if (exists $deprecated_keywords{$keyword}) {
1829                 my $new_keyword = $deprecated_keywords{$keyword};
1830                 warning("'$keyword' is deprecated, please use '$new_keyword' instead");
1831                 $keyword = $new_keyword;
1832             }
1833
1834             # effectuation operator
1835             if ($keyword eq ';') {
1836                 error('Empty rule before ";" not allowed')
1837                   unless $rule{non_empty};
1838
1839                 if ($rule{has_rule} and not exists $rule{has_action}) {
1840                     # something is wrong when a rule was specified,
1841                     # but no action
1842                     error('No action defined; did you mean "NOP"?');
1843                 }
1844
1845                 error('No chain defined') unless exists $rule{chain};
1846
1847                 $rule{script} = { filename => $script->{filename},
1848                                      line => $script->{line},
1849                                    };
1850
1851                 mkrules(\%rule);
1852
1853                 # and clean up variables set in this level
1854                 new_level(%rule, $prev);
1855
1856                 next;
1857             }
1858
1859             # conditional expression
1860             if ($keyword eq '@if') {
1861                 unless (eval_bool(getvalues)) {
1862                     collect_tokens;
1863                     my $token = peek_token();
1864                     if ($token and $token eq '@else') {
1865                         require_next_token();
1866                     } else {
1867                         new_level(%rule, $prev);
1868                     }
1869                 }
1870
1871                 next;
1872             }
1873
1874             if ($keyword eq '@else') {
1875                 # hack: if this "else" has not been eaten by the "if"
1876                 # handler above, we believe it came from an if clause
1877                 # which evaluated "true" - remove the "else" part now.
1878                 collect_tokens;
1879                 next;
1880             }
1881
1882             # hooks for custom shell commands
1883             if ($keyword eq 'hook') {
1884                 warning("'hook' is deprecated, use '\@hook'");
1885                 $keyword = '@hook';
1886             }
1887
1888             if ($keyword eq '@hook') {
1889                 error('"hook" must be the first token in a command')
1890                   if exists $rule{domain};
1891
1892                 my $position = getvar();
1893                 my $hooks;
1894                 if ($position eq 'pre') {
1895                     $hooks = \@pre_hooks;
1896                 } elsif ($position eq 'post') {
1897                     $hooks = \@post_hooks;
1898                 } elsif ($position eq 'flush') {
1899                     $hooks = \@flush_hooks;
1900                 } else {
1901                     error("Invalid hook position: '$position'");
1902                 }
1903
1904                 push @$hooks, getvar();
1905
1906                 expect_token(';');
1907                 next;
1908             }
1909
1910             # recursing operators
1911             if ($keyword eq '{') {
1912                 # push stack
1913                 my $old_stack_depth = @stack;
1914
1915                 unshift @stack, { auto => { %{$stack[0]{auto} || {}} } };
1916
1917                 # recurse
1918                 enter($lev + 1, \%rule);
1919
1920                 # pop stack
1921                 shift @stack;
1922                 die unless @stack == $old_stack_depth;
1923
1924                 # after a block, the command is finished, clear this
1925                 # level
1926                 new_level(%rule, $prev);
1927
1928                 next;
1929             }
1930
1931             if ($keyword eq '}') {
1932                 error('Unmatched "}"')
1933                   if $lev <= $base_level;
1934
1935                 # consistency check: check if they havn't forgotten
1936                 # the ';' after the last statement
1937                 error('Missing semicolon before "}"')
1938                   if $rule{non_empty};
1939
1940                 # and exit
1941                 return;
1942             }
1943
1944             # include another file
1945             if ($keyword eq '@include' or $keyword eq 'include') {
1946                 my @files = collect_filenames to_array getvalues;
1947                 $keyword = next_token;
1948                 error('Missing ";" - "include FILENAME" must be the last command in a rule')
1949                   unless defined $keyword and $keyword eq ';';
1950
1951                 foreach my $filename (@files) {
1952                     # save old script, open new script
1953                     my $old_script = $script;
1954                     open_script($filename);
1955                     $script->{base_level} = $lev + 1;
1956
1957                     # push stack
1958                     my $old_stack_depth = @stack;
1959
1960                     my $stack = {};
1961
1962                     if (@stack > 0) {
1963                         # include files may set variables for their parent
1964                         $stack->{vars} = ($stack[0]{vars} ||= {});
1965                         $stack->{functions} = ($stack[0]{functions} ||= {});
1966                         $stack->{auto} = { %{ $stack[0]{auto} || {} } };
1967                     }
1968
1969                     my( $volume,$dirs,$file ) = File::Spec->splitpath( $filename );
1970                     $stack->{auto}{FILENAME} = $filename;
1971                     $stack->{auto}{FILEBNAME} = $file;
1972                     $stack->{auto}{DIRNAME} = $dirs;
1973
1974                     unshift @stack, $stack;
1975
1976                     # parse the script
1977                     enter($lev + 1, \%rule);
1978
1979                     #check for exit status
1980                     error("'$script->{filename}': exit status is not 0") if not close $script->{handle};
1981
1982                     # pop stack
1983                     shift @stack;
1984                     die unless @stack == $old_stack_depth;
1985
1986                     # restore old script
1987                     $script = $old_script;
1988                 }
1989
1990                 next;
1991             }
1992
1993             # definition of a variable or function
1994             if ($keyword eq '@def' or $keyword eq 'def') {
1995                 error('"def" must be the first token in a command')
1996                   if $rule{non_empty};
1997
1998                 my $type = require_next_token();
1999                 if ($type eq '$') {
2000                     my $name = require_next_token();
2001                     error('invalid variable name')
2002                       unless $name =~ /^\w+$/;
2003
2004                     expect_token('=');
2005
2006                     my $value = getvalues(undef, allow_negation => 1);
2007
2008                     expect_token(';');
2009
2010                     $stack[0]{vars}{$name} = $value
2011                       unless exists $stack[-1]{vars}{$name};
2012                 } elsif ($type eq '&') {
2013                     my $name = require_next_token();
2014                     error('invalid function name')
2015                       unless $name =~ /^\w+$/;
2016
2017                     expect_token('(', 'function parameter list or "()" expected');
2018
2019                     my @params;
2020                     while (1) {
2021                         my $token = require_next_token();
2022                         last if $token eq ')';
2023
2024                         if (@params > 0) {
2025                             error('"," expected')
2026                               unless $token eq ',';
2027
2028                             $token = require_next_token();
2029                         }
2030
2031                         error('"$" and parameter name expected')
2032                           unless $token eq '$';
2033
2034                         $token = require_next_token();
2035                         error('invalid function parameter name')
2036                           unless $token =~ /^\w+$/;
2037
2038                         push @params, $token;
2039                     }
2040
2041                     my %function;
2042
2043                     $function{params} = \@params;
2044
2045                     expect_token('=');
2046
2047                     my $tokens = collect_tokens();
2048                     $function{block} = 1 if grep { $_ eq '{' } @$tokens;
2049                     $function{tokens} = $tokens;
2050
2051                     $stack[0]{functions}{$name} = \%function
2052                       unless exists $stack[-1]{functions}{$name};
2053                 } else {
2054                     error('"$" (variable) or "&" (function) expected');
2055                 }
2056
2057                 next;
2058             }
2059
2060             # this rule has something which isn't inherited by its
2061             # parent closure.  This variable is used in a lot of
2062             # syntax checks.
2063
2064             $rule{non_empty} = 1;
2065
2066             # def references
2067             if ($keyword eq '$') {
2068                 error('variable references are only allowed as keyword parameter');
2069             }
2070
2071             if ($keyword eq '&') {
2072                 my $name = require_next_token();
2073                 error('function name expected')
2074                   unless $name =~ /^\w+$/;
2075
2076                 my $function = lookup_function($name);
2077                 error("no such function: \&$name")
2078                   unless defined $function;
2079
2080                 my $paramdef = $function->{params};
2081                 die unless defined $paramdef;
2082
2083                 my @params = get_function_params(allow_negation => 1);
2084
2085                 error("Wrong number of parameters for function '\&$name': "
2086                       . @$paramdef . " expected, " . @params . " given")
2087                   unless @params == @$paramdef;
2088
2089                 my %vars;
2090                 for (my $i = 0; $i < @params; $i++) {
2091                     $vars{$paramdef->[$i]} = $params[$i];
2092                 }
2093
2094                 if ($function->{block}) {
2095                     # block {} always ends the current rule, so if the
2096                     # function contains a block, we have to require
2097                     # the calling rule also ends here
2098                     expect_token(';');
2099                 }
2100
2101                 my @tokens = @{$function->{tokens}};
2102                 for (my $i = 0; $i < @tokens; $i++) {
2103                     if ($tokens[$i] eq '$' and $i + 1 < @tokens and
2104                         exists $vars{$tokens[$i + 1]}) {
2105                         my @value = to_array($vars{$tokens[$i + 1]});
2106                         @value = ('(', @value, ')')
2107                           unless @tokens == 1;
2108                         splice(@tokens, $i, 2, @value);
2109                         $i += @value - 2;
2110                     } elsif ($tokens[$i] =~ m,^"(.*)"$,) {
2111                         $tokens[$i] =~ s,\$(\w+),exists $vars{$1} ? $vars{$1} : "\$$1",eg;
2112                     }
2113                 }
2114
2115                 unshift @{$script->{tokens}}, @tokens;
2116
2117                 next;
2118             }
2119
2120             # where to put the rule?
2121             if ($keyword eq 'domain') {
2122                 error('Domain is already specified')
2123                   if exists $rule{domain};
2124
2125                 my $domains = getvalues();
2126                 if (ref $domains) {
2127                     my $tokens = collect_tokens(include_semicolon => 1,
2128                                                 include_else => 1);
2129
2130                     my $old_line = $script->{line};
2131                     my $old_handle = $script->{handle};
2132                     my $old_tokens = $script->{tokens};
2133                     my $old_base_level = $script->{base_level};
2134                     unshift @$old_tokens, make_line_token($script->{line});
2135                     delete $script->{handle};
2136
2137                     for my $domain (@$domains) {
2138                         my %inner;
2139                         new_level(%inner, \%rule);
2140                         set_domain(%inner, $domain) or next;
2141                         $inner{domain_both} = 1;
2142                         $script->{base_level} = 0;
2143                         $script->{tokens} = [ @$tokens ];
2144                         enter(0, \%inner);
2145                     }
2146
2147                     $script->{base_level} = $old_base_level;
2148                     $script->{tokens} = $old_tokens;
2149                     $script->{handle} = $old_handle;
2150                     $script->{line} = $old_line;
2151
2152                     new_level(%rule, $prev);
2153                 } else {
2154                     unless (set_domain(%rule, $domains)) {
2155                         collect_tokens();
2156                         new_level(%rule, $prev);
2157                     }
2158                 }
2159
2160                 next;
2161             }
2162
2163             if ($keyword eq 'table') {
2164                 warning('Table is already specified')
2165                   if exists $rule{table};
2166                 $rule{table} = $stack[0]{auto}{TABLE} = getvalues();
2167
2168                 set_domain(%rule, $option{domain} || 'ip')
2169                   unless exists $rule{domain};
2170
2171                 next;
2172             }
2173
2174             if ($keyword eq 'chain') {
2175                 warning('Chain is already specified')
2176                   if exists $rule{chain};
2177
2178                 my $chain = $rule{chain} = $stack[0]{auto}{CHAIN} = getvalues();
2179
2180                 # ferm 1.1 allowed lower case built-in chain names
2181                 foreach (ref $rule{chain} ? @{$rule{chain}} : $rule{chain}) {
2182                     error('Please write built-in chain names in upper case')
2183                       if /^(?:input|forward|output|prerouting|postrouting)$/;
2184                 }
2185
2186                 set_domain(%rule, $option{domain} || 'ip')
2187                   unless exists $rule{domain};
2188
2189                 $rule{table} = 'filter'
2190                   unless exists $rule{table};
2191
2192                 my $domain = $rule{domain};
2193                 foreach my $table (to_array $rule{table}) {
2194                     foreach my $c (to_array $chain) {
2195                         $domains{$domain}{tables}{$table}{chains}{$c} ||= {};
2196                     }
2197                 }
2198
2199                 next;
2200             }
2201
2202             error('Chain must be specified')
2203               unless exists $rule{chain};
2204
2205             # policy for built-in chain
2206             if ($keyword eq 'policy') {
2207                 error('Cannot specify matches for policy')
2208                   if $rule{has_rule};
2209
2210                 my $policy = getvar();
2211                 error("Invalid policy target: $policy")
2212                   unless is_netfilter_core_target($policy);
2213
2214                 expect_token(';');
2215
2216                 my $domain = $rule{domain};
2217                 my $domain_info = $domains{$domain};
2218                 $domain_info->{enabled} = 1;
2219
2220                 foreach my $table (to_array $rule{table}) {
2221                     foreach my $chain (to_array $rule{chain}) {
2222                         $domain_info->{tables}{$table}{chains}{$chain}{policy} = $policy;
2223                     }
2224                 }
2225
2226                 new_level(%rule, $prev);
2227                 next;
2228             }
2229
2230             # create a subchain
2231             if ($keyword eq '@subchain' or $keyword eq 'subchain') {
2232                 error('Chain must be specified')
2233                   unless exists $rule{chain};
2234
2235                 error('No rule specified before "@subchain"')
2236                   unless $rule{has_rule};
2237
2238                 my $subchain;
2239                 my $token = peek_token();
2240
2241                 if ($token =~ /^(["'])(.*)\1$/s) {
2242                     $subchain = $2;
2243                     next_token();
2244                     $keyword = next_token();
2245                 } elsif ($token eq '{') {
2246                     $keyword = next_token();
2247                     $subchain = 'ferm_auto_' . ++$auto_chain;
2248                 } else {
2249                     $subchain = getvar();
2250                     $keyword = next_token();
2251                 }
2252
2253                 my $domain = $rule{domain};
2254                 foreach my $table (to_array $rule{table}) {
2255                     $domains{$domain}{tables}{$table}{chains}{$subchain} ||= {};
2256                 }
2257
2258                 set_target(%rule, 'jump', $subchain);
2259
2260                 error('"{" or chain name expected after "@subchain"')
2261                   unless $keyword eq '{';
2262
2263                 # create a deep copy of %rule, only containing values
2264                 # which must be in the subchain
2265                 my %inner = ( cow => { keywords => 1, },
2266                               match => {},
2267                               options => [],
2268                             );
2269                 $inner{$_} = $rule{$_} foreach qw(domain domain_family domain_both table keywords);
2270                 $inner{chain} = $inner{auto}{CHAIN} = $subchain;
2271
2272                 if (exists $rule{protocol}) {
2273                     $inner{protocol} = $rule{protocol};
2274                     append_option(%inner, 'protocol', $inner{protocol});
2275                 }
2276
2277                 # create a new stack frame
2278                 my $old_stack_depth = @stack;
2279                 my $stack = { auto => { %{$stack[0]{auto} || {}} } };
2280                 $stack->{auto}{CHAIN} = $subchain;
2281                 unshift @stack, $stack;
2282
2283                 # enter the block
2284                 enter($lev + 1, \%inner);
2285
2286                 # pop stack frame
2287                 shift @stack;
2288                 die unless @stack == $old_stack_depth;
2289
2290                 # now handle the parent - it's a jump to the sub chain
2291                 $rule{script} = {
2292                     filename => $script->{filename},
2293                     line => $script->{line},
2294                 };
2295
2296                 mkrules(\%rule);
2297
2298                 # and clean up variables set in this level
2299                 new_level(%rule, $prev);
2300                 delete $rule{has_rule};
2301
2302                 next;
2303             }
2304
2305             # everything else must be part of a "real" rule, not just
2306             # "policy only"
2307             $rule{has_rule} = 1;
2308
2309             # extended parameters:
2310             if ($keyword =~ /^mod(?:ule)?$/) {
2311                 foreach my $module (to_array getvalues) {
2312                     next if exists $rule{match}{$module};
2313
2314                     my $domain_family = $rule{domain_family};
2315                     my $defs = $match_defs{$domain_family}{$module};
2316
2317                     append_option(%rule, 'match', $module);
2318                     $rule{match}{$module} = 1;
2319
2320                     merge_keywords(%rule, $defs->{keywords})
2321                       if defined $defs;
2322                 }
2323
2324                 next;
2325             }
2326
2327             # keywords from $rule{keywords}
2328
2329             if (exists $rule{keywords}{$keyword}) {
2330                 my $def = $rule{keywords}{$keyword};
2331                 parse_option($def, %rule, \$negated);
2332                 next;
2333             }
2334
2335             ###
2336             # actions
2337             #
2338
2339             # jump action
2340             if ($keyword eq 'jump') {
2341                 set_target(%rule, 'jump', getvar());
2342                 next;
2343             };
2344
2345             # goto action
2346             if ($keyword eq 'realgoto') {
2347                 set_target(%rule, 'goto', getvar());
2348                 next;
2349             };
2350
2351             # action keywords
2352             if (is_netfilter_core_target($keyword)) {
2353                 set_target(%rule, 'jump', $keyword);
2354                 next;
2355             }
2356
2357             if ($keyword eq 'NOP') {
2358                 error('There can only one action per rule')
2359                   if exists $rule{has_action};
2360                 $rule{has_action} = 1;
2361                 next;
2362             }
2363
2364             if (my $defs = is_netfilter_module_target($rule{domain_family}, $keyword)) {
2365                 set_module_target(%rule, $keyword, $defs);
2366                 next;
2367             }
2368
2369             ###
2370             # protocol specific options
2371             #
2372
2373             if ($keyword eq 'proto' or $keyword eq 'protocol') {
2374                 my $protocol = parse_keyword(%rule,
2375                                              { params => 1, negation => 1 },
2376                                              \$negated);
2377                 $rule{protocol} = $protocol;
2378                 append_option(%rule, 'protocol', $rule{protocol});
2379
2380                 unless (ref $protocol) {
2381                     $protocol = netfilter_canonical_protocol($protocol);
2382                     my $domain_family = $rule{domain_family};
2383                     if (my $defs = $proto_defs{$domain_family}{$protocol}) {
2384                         merge_keywords(%rule, $defs->{keywords});
2385                         my $module = netfilter_protocol_module($protocol);
2386                         $rule{match}{$module} = 1;
2387                     }
2388                 }
2389                 next;
2390             }
2391
2392             # port switches
2393             if ($keyword =~ /^[sd]port$/) {
2394                 my $proto = $rule{protocol};
2395                 error('To use sport or dport, you have to specify "proto tcp" or "proto udp" first')
2396                   unless defined $proto and grep { /^(?:tcp|udp|udplite|dccp|sctp)$/ } to_array $proto;
2397
2398                 append_option(%rule, $keyword,
2399                               getvalues(undef, allow_negation => 1));
2400                 next;
2401             }
2402
2403             # default
2404             error("Unrecognized keyword: $keyword");
2405         }
2406
2407         # if the rule didn't reset the negated flag, it's not
2408         # supported
2409         error("Doesn't support negation: $keyword")
2410           if $negated;
2411     }
2412
2413     error('Missing "}" at end of file')
2414       if $lev > $base_level;
2415
2416     # consistency check: check if they havn't forgotten
2417     # the ';' before the last statement
2418     error("Missing semicolon before end of file")
2419       if $rule{non_empty};
2420 }
2421
2422 sub execute_command {
2423     my ($command, $script) = @_;
2424
2425     print LINES "$command\n"
2426       if $option{lines};
2427     return if $option{noexec};
2428
2429     my $ret = system($command);
2430     unless ($ret == 0) {
2431         if ($? == -1) {
2432             print STDERR "failed to execute: $!\n";
2433             exit 1;
2434         } elsif ($? & 0x7f) {
2435             printf STDERR "child died with signal %d\n", $? & 0x7f;
2436             return 1;
2437         } else {
2438             print STDERR "(rule declared in $script->{filename}:$script->{line})\n"
2439               if defined $script;
2440             return $? >> 8;
2441         }
2442     }
2443
2444     return;
2445 }
2446
2447 sub execute_slow($) {
2448     my $domain_info = shift;
2449
2450     my $domain_cmd = $domain_info->{tools}{tables};
2451
2452     my $status;
2453     while (my ($table, $table_info) = each %{$domain_info->{tables}}) {
2454         my $table_cmd = "$domain_cmd -t $table";
2455
2456         # reset chain policies
2457         while (my ($chain, $chain_info) = each %{$table_info->{chains}}) {
2458             next unless $chain_info->{builtin} or
2459               (not $table_info->{has_builtin} and
2460                is_netfilter_builtin_chain($table, $chain));
2461             $status ||= execute_command("$table_cmd -P $chain ACCEPT")
2462               unless $option{noflush};
2463         }
2464
2465         # clear
2466         unless ($option{noflush}) {
2467             $status ||= execute_command("$table_cmd -F");
2468             $status ||= execute_command("$table_cmd -X");
2469         }
2470
2471         next if $option{flush};
2472
2473         # create chains / set policy
2474         while (my ($chain, $chain_info) = each %{$table_info->{chains}}) {
2475             if (is_netfilter_builtin_chain($table, $chain)) {
2476                 if (exists $chain_info->{policy}) {
2477                     $status ||= execute_command("$table_cmd -P $chain $chain_info->{policy}")
2478                       unless $chain_info->{policy} eq 'ACCEPT';
2479                 }
2480             } else {
2481                 if (exists $chain_info->{policy}) {
2482                     $status ||= execute_command("$table_cmd -N $chain -P $chain_info->{policy}");
2483                 }
2484                 else {
2485                     $status ||= execute_command("$table_cmd -N $chain");
2486                 }
2487             }
2488         }
2489
2490         # dump rules
2491         while (my ($chain, $chain_info) = each %{$table_info->{chains}}) {
2492             my $chain_cmd = "$table_cmd -A $chain";
2493             foreach my $rule (@{$chain_info->{rules}}) {
2494                 $status ||= execute_command($chain_cmd . $rule->{rule});
2495             }
2496         }
2497     }
2498
2499     return $status;
2500 }
2501
2502 sub table_to_save($$) {
2503     my ($result_r, $table_info) = @_;
2504
2505     foreach my $chain (sort keys %{$table_info->{chains}}) {
2506         my $chain_info = $table_info->{chains}{$chain};
2507         foreach my $rule (@{$chain_info->{rules}}) {
2508             $$result_r .= "-A $chain$rule->{rule}\n";
2509         }
2510     }
2511 }
2512
2513 sub rules_to_save($) {
2514     my ($domain_info) = @_;
2515
2516     # convert this into an iptables-save text
2517     my $result = "# Generated by ferm $VERSION on " . localtime() . "\n";
2518
2519     while (my ($table, $table_info) = each %{$domain_info->{tables}}) {
2520         # select table
2521         $result .= '*' . $table . "\n";
2522
2523         # create chains / set policy
2524         foreach my $chain (sort keys %{$table_info->{chains}}) {
2525             my $chain_info = $table_info->{chains}{$chain};
2526             my $policy = $option{flush} ? undef : $chain_info->{policy};
2527             unless (defined $policy) {
2528                 if (is_netfilter_builtin_chain($table, $chain)) {
2529                     $policy = 'ACCEPT';
2530                 } else {
2531                     next if $option{flush};
2532                     $policy = '-';
2533                 }
2534             }
2535             $result .= ":$chain $policy\ [0:0]\n";
2536         }
2537
2538         table_to_save(\$result, $table_info)
2539           unless $option{flush};
2540
2541         # do it
2542         $result .= "COMMIT\n";
2543     }
2544
2545     return $result;
2546 }
2547
2548 sub restore_domain($$) {
2549     my ($domain_info, $save) = @_;
2550
2551     my $path = $domain_info->{tools}{'tables-restore'};
2552     $path .= " --noflush" if $option{noflush};
2553
2554     local *RESTORE;
2555     open RESTORE, "|$path"
2556       or die "Failed to run $path: $!\n";
2557
2558     print RESTORE $save;
2559
2560     close RESTORE
2561       or die "Failed to run $path\n";
2562 }
2563
2564 sub execute_fast($) {
2565     my $domain_info = shift;
2566
2567     my $save = rules_to_save($domain_info);
2568
2569     if ($option{lines}) {
2570         my $path = $domain_info->{tools}{'tables-restore'};
2571         $path .= " --noflush" if $option{noflush};
2572         print LINES "$path <<EOT\n"
2573           if $option{shell};
2574         print LINES $save;
2575         print LINES "EOT\n"
2576           if $option{shell};
2577     }
2578
2579     return if $option{noexec};
2580
2581     eval {
2582         restore_domain($domain_info, $save);
2583     };
2584     if ($@) {
2585         print STDERR $@;
2586         return 1;
2587     }
2588
2589     return;
2590 }
2591
2592 sub rollback() {
2593     my $error;
2594     while (my ($domain, $domain_info) = each %domains) {
2595         next unless $domain_info->{enabled};
2596         unless (defined $domain_info->{tools}{'tables-restore'}) {
2597             print STDERR "Cannot rollback domain '$domain' because there is no ${domain}tables-restore\n";
2598             next;
2599         }
2600
2601         my $reset = '';
2602         while (my ($table, $table_info) = each %{$domain_info->{tables}}) {
2603             my $reset_chain = '';
2604             foreach my $chain (keys %{$table_info->{chains}}) {
2605                 next unless is_netfilter_builtin_chain($table, $chain);
2606                 $reset_chain .= ":${chain} ACCEPT [0:0]\n";
2607             }
2608             $reset .= "*${table}\n${reset_chain}COMMIT\n"
2609               if length $reset_chain;
2610         }
2611
2612         $reset .= $domain_info->{previous}
2613           if defined $domain_info->{previous};
2614
2615         restore_domain($domain_info, $reset);
2616     }
2617
2618     print STDERR "\nFirewall rules rolled back.\n" unless $error;
2619     exit 1;
2620 }
2621
2622 sub alrm_handler {
2623     # do nothing, just interrupt a system call
2624 }
2625
2626 sub confirm_rules {
2627     $SIG{ALRM} = \&alrm_handler;
2628
2629     alarm(5);
2630
2631     print STDERR "\n"
2632       . "ferm has applied the new firewall rules.\n"
2633         . "Please type 'yes' to confirm:\n";
2634     STDERR->flush();
2635
2636     alarm($option{timeout});
2637
2638     my $line = '';
2639     STDIN->sysread($line, 3);
2640
2641     eval {
2642         require POSIX;
2643         POSIX::tcflush(*STDIN, 2);
2644     };
2645     print STDERR "$@" if $@;
2646
2647     $SIG{ALRM} = 'DEFAULT';
2648
2649     return $line eq 'yes';
2650 }
2651
2652 # end of ferm
2653
2654 __END__
2655
2656 =head1 NAME
2657
2658 ferm - a firewall rule parser for linux
2659
2660 =head1 SYNOPSIS
2661
2662 B<ferm> I<options> I<inputfiles>
2663
2664 =head1 OPTIONS
2665
2666  -n, --noexec      Do not execute the rules, just simulate
2667  -F, --flush       Flush all netfilter tables managed by ferm
2668  -l, --lines       Show all rules that were created
2669  -i, --interactive Interactive mode: revert if user does not confirm
2670  -t, --timeout s   Define interactive mode timeout in seconds
2671  --remote          Remote mode; ignore host specific configuration.
2672                    This implies --noexec and --lines.
2673  -V, --version     Show current version number
2674  -h, --help        Look at this text
2675  --slow            Slow mode, don't use iptables-restore
2676  --shell           Generate a shell script which calls iptables-restore
2677  --domain {ip|ip6} Handle only the specified domain
2678  --def '$name=v'   Override a variable
2679
2680 =cut