| 1 | #!/usr/bin/perl |
| 2 | # Encrypting VPN tunnel for use with userv-ipif. |
| 3 | # |
| 4 | # This comment is reference documentation. See ipif/INSTALL for the |
| 5 | # installation instructions and setup tutorial. |
| 6 | # |
| 7 | # usage: |
| 8 | # To make a tunnel between two machines `alice' and `bob', |
| 9 | # on `alice', the active endpoint, run: |
| 10 | # |
| 11 | # udptunnel |
| 12 | # [ -l[<alice-command/arg>] ... . |
| 13 | # | -e <encryption-mech>[/<encryption-parameter>...] |
| 14 | # | -m (`masquerade support': bob gets `Wait' instead of our addr/port) |
| 15 | # | -d (`dump keys': when no peer, spew keys rather than reading them; |
| 16 | # we always send keys to our peer if there is one) |
| 17 | # | -Dcrypto (debug crypto - use with care, prints keys, packets &c on screen!) |
| 18 | # | -f<path-to-udptunnel-forwarder> |
| 19 | # ... |
| 20 | # ] |
| 21 | # <alice-phys-addr>,<alice-phys-port> |
| 22 | # <bob-phys-addr>,<bob-phys-port> |
| 23 | # <alice-virt-addr>,<bob-virt-addr>,<mtu>,<proto> |
| 24 | # <keepalive>,<timeout>[,<reannounce>] |
| 25 | # <alice-priv-nets> <bob-priv-nets> |
| 26 | # [ <bob-command> [<bob-args> ...] ] |
| 27 | # |
| 28 | # This will run udptunnel-forwarder on alice, and use <bob-command> |
| 29 | # (usually an ssh invocation) to run udptunnel appropriately on bob. |
| 30 | # Key material will be generated by alice and fed to udptunnel on bob |
| 31 | # via <bob-command>'s stdin, and the physical address and port on bob |
| 32 | # will be (if so configured) returned via <bob-command>'s stdout. |
| 33 | # |
| 34 | # The tunnel will stay up until one of the subprocesses involved dies, |
| 35 | # or the keepalive timeout expires. If you want the tunnel to remain |
| 36 | # up permanently, you must arrange to invoke it repeatedly (eg, from |
| 37 | # inittab). See INSTALL. |
| 38 | # |
| 39 | # <proto> may be slip or cslip |
| 40 | # |
| 41 | # <mtu> will be the MTU of the tunnel interfaces; it is best if this |
| 42 | # is enough smaller than the path MTU between the physical interfaces |
| 43 | # that the encapsulated packets will fit without fragmentation. |
| 44 | # |
| 45 | # Any <..-addr> supplied to udptunnel may also be hostname; these will |
| 46 | # all be looked up on alice and IP addresses passed to bob. |
| 47 | # |
| 48 | # The `local' physical address and ports (ie, alice's own details), |
| 49 | # may have these special values: |
| 50 | # `Any' choose one ourselves and do not print it (the port chosen |
| 51 | # will be supplied to bob) |
| 52 | # `Print' choose one ourselves and print both port and addr |
| 53 | # (this is not usually useful specified directly; it's |
| 54 | # used by udptunnel when it invokes itself on bob via |
| 55 | # <bob-command>, to have its other self print the |
| 56 | # relevant value. |
| 57 | # |
| 58 | # The `remote' physical address and port (ie, on alice, bob's details), |
| 59 | # may also have the special values: |
| 60 | # `Command' wait for <bob-command> to tell us the values (this is |
| 61 | # usually the right choice on alice for at least the |
| 62 | # port). <bob-command> must be specified (ie, this |
| 63 | # only makes sense on alice). |
| 64 | # `Wait' alice will wait to receive a packet from bob and use |
| 65 | # whatever address and port it came from |
| 66 | # |
| 67 | # These special values are case-sensitive. When alice runs udptunnel |
| 68 | # on bob they are automatically translated to appropriate other values |
| 69 | # in the arguments to bob's udptunnel. |
| 70 | # |
| 71 | # If <bob-command> is specified it should run udptunnel at the |
| 72 | # bob end; it will be invoked as |
| 73 | # <bob-command> [ <bob-args> ... ] |
| 74 | # [ <-e arguments passed along> ] |
| 75 | # <bob-phys-addr'>,<bob-phys-port'> |
| 76 | # <alice-phys-addr'>,<alice-phys-port'> |
| 77 | # <bob-virt-addr>,<alice-virt-addr>,<mtu>,<proto> |
| 78 | # <keepalive>,<timeout>[,<reannounce>] |
| 79 | # <bob-priv-nets> <alice-priv-nets> |
| 80 | # |
| 81 | # If it was given Print for <bob-phys-foo'>, udptunnel's first stdout |
| 82 | # output will be the real <bob-phys-addr>,<bob-phys-port> pair. It |
| 83 | # may then produce more stdout which, if any, will be forwarded to the |
| 84 | # local end's stdout as debugging info. |
| 85 | # |
| 86 | # After this, if any encryption was specified, the encryption key |
| 87 | # material will be fed into its stdin. See the documentation in the |
| 88 | # mech-*.c files for details of the parameters. udptunnel on alice |
| 89 | # will arrange to feed the keys fd of udptunnel-forwarder into the |
| 90 | # stdin of the udptunnel on bob. |
| 91 | # |
| 92 | # <bob-phys-foo'> is as follows: |
| 93 | # <bob-phys-foo> <bob-phys-foo'> |
| 94 | # actual addr/port that addr/port |
| 95 | # `Command' `Print' |
| 96 | # `Wait' `Any' |
| 97 | # |
| 98 | # <alice-phys-foo'> is as follows: |
| 99 | # <alice-phys-foo> <alice-phys-foo'> <alice-phys-foo'> |
| 100 | # (-m not specified) (-m specified) |
| 101 | # actual addr/port that addr/port `Wait' |
| 102 | # `Print' the chosen address `Wait' |
| 103 | # `Any' `Wait' for addr, `Wait' |
| 104 | # chosen port for port |
| 105 | # |
| 106 | # In each case udptunnel will run userv ipif locally, as |
| 107 | # userv root ipif <local-virt-addr>,<remote-virt-addr>,<mtu>,<proto> |
| 108 | # <remote-priv-nets> |
| 109 | # or, if -l was given, userv root ipif is replaced with the argument(s) |
| 110 | # following -l option(s) until `.'. |
| 111 | # |
| 112 | # udptunnel will also run udptunnel-forwarder with appropriate options. |
| 113 | # |
| 114 | # recommended encryption parameters are: |
| 115 | # -e nonce (prepend 32 bit counter) |
| 116 | # -e timestamp/<max-skew>/<max-age> (prepend 32 bit time_t, and check on receipt) |
| 117 | # -e pkcs5/8 (pad as per PKCS#5 to 8-byte boundary) |
| 118 | # -e blowfish-cbcmac/128 (prepend CBC MAC with random IV and 128 bit key) |
| 119 | # -e blowfish-cbc/128 (encrypt with CBC, random IV and 128 bit key) |
| 120 | # where <max-skew> is perhaps 10 and <max-age> perhaps 30. If your |
| 121 | # clocks are not sufficiently well synchronised, you could replace |
| 122 | # `-e nonce -e timestamp/...' with just `-e sequence'. Do not just |
| 123 | # remove `-e timestamp/...'. |
| 124 | |
| 125 | # Copyright (C) 1999-2000 Ian Jackson |
| 126 | # |
| 127 | # This is free software; you can redistribute it and/or modify it |
| 128 | # under the terms of the GNU General Public License as published by |
| 129 | # the Free Software Foundation; either version 2 of the License, or |
| 130 | # (at your option) any later version. |
| 131 | # |
| 132 | # This program is distributed in the hope that it will be useful, but |
| 133 | # WITHOUT ANY WARRANTY; without even the implied warranty of |
| 134 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 135 | # General Public License for more details. |
| 136 | # |
| 137 | # You should have received a copy of the GNU General Public License |
| 138 | # along with userv-utils; if not, write to the Free Software |
| 139 | # Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 140 | # |
| 141 | # $Id$ |
| 142 | |
| 143 | use Socket; |
| 144 | use POSIX; |
| 145 | use Fcntl; |
| 146 | |
| 147 | $progname= $0; $progname =~ s,.*/,,; |
| 148 | $|=1; |
| 149 | |
| 150 | chomp($hostname= `uname -n`); |
| 151 | $? and die "$progname: cannot get hostname (uname failed with code $?)\n"; |
| 152 | |
| 153 | sub quit ($) { die "$progname - $hostname: fatal error: $_[0]\n"; } |
| 154 | sub debug ($) { print "$progname - $hostname: debug: $_[0]\n"; } |
| 155 | sub fail ($) { quit("unexpected system call failure: $_[0]: $!"); } |
| 156 | sub warning ($) { warn "$progname - $hostname: $_[0]\n"; } |
| 157 | |
| 158 | sub eat_addr_port ($) { |
| 159 | my ($x) = @_; |
| 160 | @ARGV or quit("<addr>,<port> missing"); |
| 161 | $_= shift(@ARGV); |
| 162 | (m/^$x,/i && m/^[a-z]/ || m/,$x$/i && m/,[a-z]/) |
| 163 | and warning("$_: use Mixed Case for special values"); |
| 164 | m/^([0-9a-z][0-9a-z-+.]+|$x)\,(\d+|$x)$/ |
| 165 | or quit("$_: <host/addr>,<port> bad syntax". |
| 166 | (m/[A-Z]/ ? ' (use lowercase for hostnames)' : '')); |
| 167 | return ($1,$2); |
| 168 | } |
| 169 | sub conv_host_addr ($) { |
| 170 | my ($s,$r,@h) = @_; |
| 171 | return INADDR_ANY() if $s =~ m/^[A-Z][a-z]/; |
| 172 | return $r if defined($r= inet_aton($s)); |
| 173 | @h= gethostbyname($s) or quit("$s: cannot get address"); |
| 174 | $h[2] eq &AF_INET or quit("$s: address is not IPv4"); |
| 175 | @h < 5 or quit("$s: name maps to no addresses"); |
| 176 | $r= $h[4]; |
| 177 | @h == 5 or warning("$s: name has several addresses, using ".inet_ntoa($r)); |
| 178 | return $r; |
| 179 | } |
| 180 | sub conv_port_number ($) { |
| 181 | my ($s,$r) = @_; |
| 182 | return 0 if $s =~ m/^[A-Z][a-z]/; |
| 183 | $r= $s+0; |
| 184 | $r>0 && $r<65536 or quit("$s: port out of range"); |
| 185 | return $r; |
| 186 | } |
| 187 | sub show_addr ($) { |
| 188 | my ($s,@s) = @_; |
| 189 | @s= unpack_sockaddr_in($s); |
| 190 | return inet_ntoa($s[1]); |
| 191 | } |
| 192 | sub show_port ($) { |
| 193 | my ($s,@s) = @_; |
| 194 | @s= unpack_sockaddr_in($s); |
| 195 | return $s[0]; |
| 196 | } |
| 197 | sub show_addr_port ($) { |
| 198 | my ($s) = @_; |
| 199 | return show_addr($s).','.show_port($s); |
| 200 | } |
| 201 | sub arg_value ($$) { |
| 202 | my ($val,$opt) = @_; |
| 203 | $_= '-'; |
| 204 | return $val if length $val; |
| 205 | @ARGV or quit("$opt needs value"); |
| 206 | return shift @ARGV; |
| 207 | } |
| 208 | |
| 209 | @lcmd= (); |
| 210 | @encryption= (); |
| 211 | $masq= 0; |
| 212 | $dump= 0; |
| 213 | $fcmd= 'udptunnel-forwarder'; |
| 214 | $xfwdopts= ''; |
| 215 | |
| 216 | while ($ARGV[0] =~ m/^-/) { |
| 217 | $_= shift @ARGV; |
| 218 | last if m/^--?$/; |
| 219 | while (!m/^-$/) { |
| 220 | if (s/^-l//) { |
| 221 | push @lcmd,$_ if length; |
| 222 | while (@ARGV && ($_= shift @ARGV) ne '.') { push @lcmd, $_; } |
| 223 | $_= '-' |
| 224 | } elsif (s/^-f//) { |
| 225 | $fcmd= arg_value($_,'-f'); |
| 226 | } elsif (s/^-e//) { |
| 227 | $encrarg= arg_value($_,'-e'); |
| 228 | push @remoteopts, "-e$encrarg"; |
| 229 | @thisencryption= split m#/#, $encrarg; |
| 230 | $thisencryption[0] =~ s/^/\|/; |
| 231 | push @encryption, @thisencryption; |
| 232 | } elsif (s/^-m/-/) { |
| 233 | $masq= 1; |
| 234 | } elsif (s/^-d/-/) { |
| 235 | $dump= 1; |
| 236 | } elsif (s/^-Dcrypto$/-/) { |
| 237 | $xfwdopts.= 'K'; |
| 238 | push @remoteopts, '-Dcrypto'; |
| 239 | } else { |
| 240 | quit("unknown option \`$_'"); |
| 241 | } |
| 242 | } |
| 243 | } |
| 244 | |
| 245 | # Variables \$[lr]a?p?(|s|d|r) |
| 246 | # Local/Remote Address&/Port |
| 247 | # actualvalue/Specified/Displaypassdown/fromRemote/passtoForwarder |
| 248 | # |
| 249 | ($las,$lps)= eat_addr_port('Print|Any'); |
| 250 | $la= conv_host_addr($las); |
| 251 | $lp= conv_port_number($lps); |
| 252 | $ls= pack_sockaddr_in $lp,$la; |
| 253 | |
| 254 | ($ras,$rps)= eat_addr_port('Wait|Command'); |
| 255 | $ra= conv_host_addr($ras); |
| 256 | $rp= conv_port_number($rps); |
| 257 | $rs= pack_sockaddr_in $rp,$ra; |
| 258 | |
| 259 | $_= shift @ARGV; |
| 260 | m/^([.0-9]+),([.0-9]+),(\d+),(slip|cslip)$/ |
| 261 | or quit("lvaddr,rvaddr,mtu,proto missing or bad syntax or proto not [c]slip"); |
| 262 | ($lva,$rva,$mtu,$proto) = ($1,$2,$3,$4); |
| 263 | |
| 264 | $_= shift @ARGV; |
| 265 | if (m/^(\d+),(\d+)$/) { |
| 266 | ($keepalive,$timeout,$reannounce)= ($1+0,$2+0,0); |
| 267 | $ka_to_ra= "$keepalive,$timeout"; |
| 268 | } elsif (m/^(\d+),(\d+),(\d+)$/) { |
| 269 | ($keepalive,$timeout,$reannounce)= ($1+0,$2+0,$3); |
| 270 | "$keepalive,$timeout", |
| 271 | $ka_to_ra= "$keepalive,$timeout,$reannounce"; |
| 272 | } else { |
| 273 | quit("keepalive,timeout missing or bad syntax"); |
| 274 | } |
| 275 | $keepalive && ($timeout > $keepalive*2) or quit("timeout must be < 2*keepalive") |
| 276 | if $timeout; |
| 277 | |
| 278 | # Variables \$[lr]exn |
| 279 | # Local/Remote Extra Nets |
| 280 | $lexn= shift @ARGV; |
| 281 | $rexn= shift @ARGV; |
| 282 | |
| 283 | defined($udp= getprotobyname('udp')) or fail("getprotobyname udp"); |
| 284 | |
| 285 | socket(L,PF_INET,SOCK_DGRAM,$udp) or fail("socket"); |
| 286 | bind(L,$ls) or quit("bind failed: $!"); |
| 287 | defined($ls= getsockname(L)) or fail("getsockname"); |
| 288 | $lad= show_addr($ls); |
| 289 | $lpd= show_port($ls); |
| 290 | $lapd= "$lad,$lpd"; |
| 291 | |
| 292 | print "$lapd\n" or fail("print addr/port") if ($las eq 'Print' || $lps eq 'Print'); |
| 293 | |
| 294 | $rapcmd= ($ras eq 'Command' || $rps eq 'Command'); |
| 295 | quit("need remote-command if Command for remote addr/port") if $rapcmd && !@ARGV; |
| 296 | |
| 297 | sub xform_remote ($$) { |
| 298 | my ($showed,$spec) = @_; |
| 299 | return 'Print' if $spec eq 'Command'; |
| 300 | return 'Any' if $spec eq 'Wait'; |
| 301 | return $showed; |
| 302 | } |
| 303 | |
| 304 | if (@ARGV) { |
| 305 | warning("-d specified with remote command, ignoring") if $dump; |
| 306 | $dump= 1; |
| 307 | |
| 308 | $rad= xform_remote(show_addr($rs),$ras); |
| 309 | $rpd= xform_remote(show_port($rs),$rps); |
| 310 | @rcmd= (@ARGV, |
| 311 | @remoteopts, |
| 312 | "$rad,$rpd", |
| 313 | $masq ? 'Wait,Wait' : $las eq 'Any' ? "Wait,$lpd" : $lapd, |
| 314 | "$rva,$lva,$mtu,$proto", |
| 315 | $ka_to_ra, |
| 316 | $rexn, $lexn); |
| 317 | debug("remote command @rcmd"); |
| 318 | |
| 319 | if ($rapcmd) { |
| 320 | pipe(RAPREAD,RCMDREADSUB) or fail("pipe"); |
| 321 | } |
| 322 | pipe(RCMDWRITESUB,DUMPKEYS) or fail("pipe"); |
| 323 | defined($c_rcmd= fork) or fail("fork for remote"); |
| 324 | if (!$c_rcmd) { |
| 325 | open STDIN, "<&RCMDWRITESUB" or fail("reopen stdin for remote command"); |
| 326 | open STDOUT, ">&RCMDREADSUB" or fail("reopen stdout for remote command") |
| 327 | if $rapcmd; |
| 328 | close RAPREAD if $rapcmd; |
| 329 | close DUMPKEYS; |
| 330 | close RCMDWRITESUB; |
| 331 | close RCMDREADSUB; |
| 332 | close L; |
| 333 | exec @rcmd; fail("failed to execute remote command $rcmd[0]"); |
| 334 | } |
| 335 | close RCMDWRITESUB; |
| 336 | |
| 337 | if ($rapcmd) { |
| 338 | close RCMDREADSUB if $rapcmd; |
| 339 | $_= ''; |
| 340 | while (!m/\n/) { |
| 341 | $!=0; |
| 342 | defined($nread= sysread(RAPREAD,$_,1,length)) |
| 343 | or fail("read from remote command"); |
| 344 | if (!$nread) { |
| 345 | close DUMPKEYS; |
| 346 | close RAPREAD; |
| 347 | waitpid $c_rcmd,0 or fail("wait for remote command"); |
| 348 | quit($? ? "remote command failed (code $?)" : |
| 349 | "no details received from remote"); |
| 350 | } |
| 351 | } |
| 352 | chomp; |
| 353 | m/^([.0-9]+)\,(\d+)$/ or quit("invalid details from remote end: \`$_'"); |
| 354 | ($rar,$rpr) = ($1,$2); |
| 355 | $ra= conv_host_addr($rar); |
| 356 | $rp= conv_port_number($rpr); |
| 357 | |
| 358 | defined($c_catremdebug= fork) or fail("fork for cat remote debug"); |
| 359 | if (!$c_catremdebug) { |
| 360 | open(STDIN,"<&RAPREAD") or fail("redirect remote debug"); |
| 361 | close DUMPKEYS; |
| 362 | close L; |
| 363 | exec "cat"; fail("execute cat"); |
| 364 | } |
| 365 | close RAPREAD; |
| 366 | } |
| 367 | } elsif ($dump) { |
| 368 | open DUMPKEYS, ">&STDOUT" or fail("reopen stdout for key material"); |
| 369 | $dump= 1; |
| 370 | } else { |
| 371 | open DUMPKEYS, "<&STDIN" or fail("reopen stdout for key material"); |
| 372 | } |
| 373 | |
| 374 | $rs= pack_sockaddr_in $rp,$ra; |
| 375 | |
| 376 | if ($ras eq 'Wait' || $rps eq 'Wait') { |
| 377 | @rapf= (''); |
| 378 | $rapd= ('Wait,Wait'); |
| 379 | } else { |
| 380 | @rapf= (show_addr($rs), show_port($rs)); |
| 381 | $rapd= show_addr_port($rs); |
| 382 | } |
| 383 | @lcmd= qw(userv root ipif) unless @lcmd; |
| 384 | |
| 385 | debug("using remote $rapd local $lapd"); |
| 386 | push @lcmd, ("$lva,$rva,$mtu,$proto",$lexn); |
| 387 | debug("local command @lcmd."); |
| 388 | |
| 389 | pipe(UR,UW) or fail("up pipe"); |
| 390 | pipe(DR,DW) or fail("down pipe"); |
| 391 | |
| 392 | defined($c_lcmd= fork) or fail("fork for local command"); |
| 393 | if (!$c_lcmd) { |
| 394 | close UR; close DW; |
| 395 | open(STDIN,"<&DR") or fail("reopen stdin for packets"); |
| 396 | open(STDOUT,">&UW") or fail("reopen stdout for packets"); |
| 397 | exec @lcmd; |
| 398 | quit("cannot execute $lcmd[0]: $!"); |
| 399 | } |
| 400 | close UW; |
| 401 | close DR; |
| 402 | |
| 403 | $xfwdopts.= 'w' if $dump; |
| 404 | |
| 405 | @fcmd= ($fcmd, $xfwdopts, |
| 406 | fileno(L), fileno(DW), fileno(UR), fileno(DUMPKEYS), |
| 407 | $mtu, $keepalive, $timeout, $reannounce, |
| 408 | @rapf, |
| 409 | @encryption); |
| 410 | debug("forwarding command @fcmd."); |
| 411 | |
| 412 | defined($c_fwd= fork) or fail("fork for udptunnel-forwarder"); |
| 413 | if (!$c_fwd) { |
| 414 | foreach $fd (qw(L DW UR DUMPKEYS)) { |
| 415 | fcntl($fd, F_SETFD, 0) or fail("set no-close-on-exec $fd"); |
| 416 | } |
| 417 | exec @fcmd; fail("cannot execute $fcmd[0]"); |
| 418 | } |
| 419 | |
| 420 | close L; |
| 421 | close DUMPKEYS; |
| 422 | close UR; |
| 423 | close DW; |
| 424 | |
| 425 | %procs= ($c_fwd, 'forwarder', |
| 426 | $c_lcmd, 'local command'); |
| 427 | $procs{$c_rcmd}= 'remote command' if $c_rcmd; |
| 428 | $procs{$c_catremdebug}= 'debug cat' if $c_catremdebug; |
| 429 | |
| 430 | $estatus= 0; |
| 431 | |
| 432 | while (keys %procs) { |
| 433 | ($c= wait) >0 or |
| 434 | fail("wait failed (expecting ". join('; ',keys %procs). ")"); |
| 435 | $status= $?; |
| 436 | warning("unexpected child reaped: pid $c, code $status"), next |
| 437 | unless exists $procs{$c}; |
| 438 | $str= $procs{$c}; |
| 439 | delete $procs{$c}; |
| 440 | $status ? warning("subprocess $str failed with code $status") |
| 441 | : debug("subprocess $str finished"); |
| 442 | if ($c==$c_lcmd || $c==$c_fwd || $c==$c_rcmd) { |
| 443 | kill 15, grep (exists $procs{$_}, $c_fwd, $c_rcmd); |
| 444 | } |
| 445 | $estatus=1 unless $c == $c_catremdebug; |
| 446 | } |
| 447 | |
| 448 | debug("all processes terminated, exiting with status $estatus"); |
| 449 | |
| 450 | exit $estatus; |