| 1 | /* |
| 2 | * userv service (or standalone program) for per-user IP subranges. |
| 3 | * |
| 4 | * When invoked appropriately, it creates a point-to-point network |
| 5 | * interface with specified parameters. It arranges for packets sent out |
| 6 | * via that interface by the kernel to appear on its own stdout in SLIP or |
| 7 | * CSLIP encoding, and packets injected into its own stdin to be given to |
| 8 | * the kernel as if received on that interface. Optionally, additional |
| 9 | * routes can be set up to arrange for traffic for other address ranges to |
| 10 | * be routed through the new interface. |
| 11 | * |
| 12 | * This is the service program, which is invoked as root from userv (or may |
| 13 | * be invoked firectly). |
| 14 | * |
| 15 | * Its arguments are supposed to be, in order, as follows: |
| 16 | * |
| 17 | * The first two arguments are usually supplied by the userv |
| 18 | * configuration. See the file `ipif/ipif' in the source tree, which |
| 19 | * is installed in /etc/userv/services.d/ipif by `make install': |
| 20 | * |
| 21 | * <config> |
| 22 | * |
| 23 | * Specifies address ranges and gids which own them. The default |
| 24 | * configuration supplies /etc/userv/ipif-networks, which is then read |
| 25 | * for a list of entries, one per line. |
| 26 | * |
| 27 | * -- |
| 28 | * Serves to separate the user-supplied and therefore untrusted |
| 29 | * arguments from the trusted first argument. |
| 30 | * |
| 31 | * The remaining arguments are supplied by the (untrusted) caller: |
| 32 | * |
| 33 | * <local-addr>,<peer-addr>,<mtu>,<proto> |
| 34 | * |
| 35 | * As for slattach. The only supported protocol is slip. |
| 36 | * Alternatively, set to `debug' to print debugging info and |
| 37 | * exit. <local-addr> is address of the interface to be created |
| 38 | * on the local system; <peer-addr> is the address of the |
| 39 | * point-to-point peer. They must be actual addresses (not |
| 40 | * hostnames). |
| 41 | * |
| 42 | * <prefix>/<mask>,<prefix>/<mask>,... |
| 43 | * |
| 44 | * List of additional routes to add for this interface. routes will |
| 45 | * be set up on the local system arranging for packets for those |
| 46 | * networks to be sent via the created interface. <prefix> must be an |
| 47 | * IPv4 address, and mask must be an integer (dotted-quad masks are |
| 48 | * not supported). If no additional routes are to be set up, use `-' |
| 49 | * or supply an empty argument. |
| 50 | * |
| 51 | * Each <config> item - whether a line in a file such as |
| 52 | * /etc/userv/ipif-networks, or the single trusted argument supplied |
| 53 | * on the service program command line - is one of: |
| 54 | * |
| 55 | * /<config-file-name> |
| 56 | * ./<config-file-name> |
| 57 | * ../<config-file-name> |
| 58 | * |
| 59 | * Reads a file which contains lines which are each <config> |
| 60 | * items. |
| 61 | * |
| 62 | * <gid>,[=][-|+]<prefix>/<len>(-|+<prefix>/<len>...)[,<junk>] |
| 63 | * |
| 64 | * Indicates that <gid> may allocate addresses in the relevant address |
| 65 | * range (<junk> is ignored). <gid> must be numeric. To specify a |
| 66 | * single host address, you must specify a mask of /32. If `=' is |
| 67 | * specified then the specific subrange is only allowed for the local |
| 68 | * endpoint address, but not for remote addresses. |
| 69 | * |
| 70 | * More than one range may be given, with each range prefixed |
| 71 | * by + or -. In this case each address range in the rule will |
| 72 | * scanned in order, and the first range in the rule that matches |
| 73 | * any desired rule will count: if that first matching range is |
| 74 | * prefixed by `+' (or nothing) then the rule applies, if it |
| 75 | * is prefixed by `-' (or nothing matches), the rule does not. |
| 76 | * |
| 77 | * * |
| 78 | * Means that anything is to be permitted. This should not appear in |
| 79 | * /etc/userv/ipif-networks, as that would permit any user on the |
| 80 | * system to create any interfaces with any addresses and routes |
| 81 | * attached. It is provided so that root can usefully invoke the ipif |
| 82 | * service program directly (not via userv), without needing to set up |
| 83 | * permissions in /etc/userv/ipif-networks. |
| 84 | * |
| 85 | * #... |
| 86 | * |
| 87 | * Comment. Blank lines are also ignored. |
| 88 | * |
| 89 | * NB: Permission is granted if _any_ config entry matches the request. |
| 90 | * |
| 91 | * The service program should be run from userv with no-disconnect-hup. |
| 92 | */ |
| 93 | /* |
| 94 | * This file is part of ipif, part of userv-utils |
| 95 | * |
| 96 | * Copyright 1996-2013 Ian Jackson <ijackson@chiark.greenend.org.uk> |
| 97 | * Copyright 1998 David Damerell <damerell@chiark.greenend.org.uk> |
| 98 | * Copyright 1999,2003 |
| 99 | * Chancellor Masters and Scholars of the University of Cambridge |
| 100 | * Copyright 2010 Tony Finch <fanf@dotat.at> |
| 101 | * |
| 102 | * This is free software; you can redistribute it and/or modify it |
| 103 | * under the terms of the GNU General Public License as published by |
| 104 | * the Free Software Foundation; either version 3 of the License, or |
| 105 | * (at your option) any later version. |
| 106 | * |
| 107 | * This program is distributed in the hope that it will be useful, but |
| 108 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 109 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 110 | * General Public License for more details. |
| 111 | * |
| 112 | * You should have received a copy of the GNU General Public License |
| 113 | * along with userv-utils; if not, see http://www.gnu.org/licenses/. |
| 114 | */ |
| 115 | |
| 116 | #include <stdio.h> |
| 117 | #include <string.h> |
| 118 | #include <stdlib.h> |
| 119 | #include <assert.h> |
| 120 | #include <errno.h> |
| 121 | #include <stdarg.h> |
| 122 | #include <ctype.h> |
| 123 | #include <limits.h> |
| 124 | #include <signal.h> |
| 125 | #include <unistd.h> |
| 126 | #include <stdint.h> |
| 127 | #include <poll.h> |
| 128 | |
| 129 | #include <sys/types.h> |
| 130 | #include <sys/wait.h> |
| 131 | #include <sys/stat.h> |
| 132 | |
| 133 | #include <sys/types.h> |
| 134 | #include <sys/ioctl.h> |
| 135 | #include <sys/socket.h> |
| 136 | |
| 137 | #include <sys/stat.h> |
| 138 | #include <fcntl.h> |
| 139 | |
| 140 | #include <linux/if.h> |
| 141 | #include <linux/if_tun.h> |
| 142 | |
| 143 | #define NARGS 4 |
| 144 | #define MAXEXROUTES 50 |
| 145 | #define ATXTLEN 16 |
| 146 | |
| 147 | static const unsigned long gidmaxval= (unsigned long)((gid_t)-2); |
| 148 | static const char *const protos_ok[]= { "slip", 0 }; |
| 149 | static const int signals[]= { SIGHUP, SIGINT, SIGTERM, 0 }; |
| 150 | |
| 151 | static const char *configstr, *proto; |
| 152 | static unsigned long localaddr, peeraddr, mtu; |
| 153 | static int localpming, peerpming; |
| 154 | static int localallow, peerallow, allallow; |
| 155 | static int nexroutes; |
| 156 | static struct exroute { |
| 157 | unsigned long prefix, mask; |
| 158 | int allow, pming; |
| 159 | char prefixtxt[ATXTLEN], masktxt[ATXTLEN]; |
| 160 | } exroutes[MAXEXROUTES]; |
| 161 | |
| 162 | static char localtxt[ATXTLEN]; |
| 163 | static char peertxt[ATXTLEN]; |
| 164 | |
| 165 | static struct pplace { |
| 166 | struct pplace *parent; |
| 167 | const char *filename; |
| 168 | int lineno; |
| 169 | } *cpplace; |
| 170 | |
| 171 | |
| 172 | static int tunfd; |
| 173 | static char *ifname; |
| 174 | |
| 175 | |
| 176 | static void terminate(int estatus) { |
| 177 | exit(estatus); |
| 178 | } |
| 179 | |
| 180 | |
| 181 | static void fatal(const char *fmt, ...) |
| 182 | __attribute__((format(printf,1,2))); |
| 183 | static void fatal(const char *fmt, ...) { |
| 184 | va_list al; |
| 185 | va_start(al,fmt); |
| 186 | |
| 187 | fputs("userv-ipif service: fatal error: ",stderr); |
| 188 | vfprintf(stderr, fmt, al); |
| 189 | putc('\n',stderr); |
| 190 | terminate(8); |
| 191 | } |
| 192 | |
| 193 | static void sysfatal(const char *fmt, ...) |
| 194 | __attribute__((format(printf,1,2))); |
| 195 | static void sysfatal(const char *fmt, ...) { |
| 196 | va_list al; |
| 197 | int e; |
| 198 | |
| 199 | e= errno; |
| 200 | va_start(al,fmt); |
| 201 | |
| 202 | fputs("userv-ipif service: fatal system error: ",stderr); |
| 203 | vfprintf(stderr, fmt, al); |
| 204 | fprintf(stderr,": %s\n", strerror(e)); |
| 205 | terminate(12); |
| 206 | } |
| 207 | |
| 208 | |
| 209 | static void badusage(const char *fmt, ...) |
| 210 | __attribute__((format(printf,1,2))); |
| 211 | static void badusage(const char *fmt, ...) { |
| 212 | va_list al; |
| 213 | struct pplace *cpp; |
| 214 | |
| 215 | if (cpplace) { |
| 216 | fprintf(stderr, |
| 217 | "userv-ipif service: %s:%d: ", |
| 218 | cpplace->filename, cpplace->lineno); |
| 219 | } else { |
| 220 | fputs("userv-ipif service: invalid usage: ",stderr); |
| 221 | } |
| 222 | va_start(al,fmt); |
| 223 | vfprintf(stderr, fmt, al); |
| 224 | putc('\n',stderr); |
| 225 | |
| 226 | if (cpplace) { |
| 227 | for (cpp=cpplace->parent; cpp; cpp=cpp->parent) { |
| 228 | fprintf(stderr, |
| 229 | "userv-ipif service: %s:%d: ... in file included from here\n", |
| 230 | cpp->filename, cpp->lineno); |
| 231 | } |
| 232 | } |
| 233 | terminate(16); |
| 234 | } |
| 235 | |
| 236 | static char *ip2txt(unsigned long addr, char *buf) { |
| 237 | sprintf(buf, "%lu.%lu.%lu.%lu", |
| 238 | (addr>>24) & 0x0ff, |
| 239 | (addr>>16) & 0x0ff, |
| 240 | (addr>>8) & 0x0ff, |
| 241 | (addr) & 0x0ff); |
| 242 | return buf; |
| 243 | } |
| 244 | |
| 245 | static unsigned long eat_number(const char **argp, const char *what, |
| 246 | unsigned long min, unsigned long max, |
| 247 | const char *endchars, int *endchar_r) { |
| 248 | /* If !endchars then the endchar must be a nul, otherwise it may be |
| 249 | * a nul (resulting in *argp set to 0) or something else (*argp set |
| 250 | * to point to after delim, *endchar_r set to delim). |
| 251 | * *endchar_r may be 0. |
| 252 | */ |
| 253 | unsigned long rv; |
| 254 | char *ep; |
| 255 | int endchar; |
| 256 | |
| 257 | if (!*argp) { badusage("missing number %s",what); } |
| 258 | rv= strtoul(*argp,&ep,0); |
| 259 | if ((endchar= *ep)) { |
| 260 | if (!endchars) badusage("junk after number %s",what); |
| 261 | if (!strchr(endchars,endchar)) |
| 262 | badusage("invalid character or delimiter `%c' in or after number, %s:" |
| 263 | " expected %s (or none?)", endchar,what,endchars); |
| 264 | *argp= ep+1; |
| 265 | } else { |
| 266 | *argp= 0; |
| 267 | } |
| 268 | if (endchar_r) *endchar_r= endchar; |
| 269 | if (rv < min || rv > max) badusage("number %s value %lu out of range %lu..%lu", |
| 270 | what, rv, min, max); |
| 271 | return rv; |
| 272 | } |
| 273 | |
| 274 | static int addrnet_overlap(unsigned long p1, unsigned long m1, |
| 275 | unsigned long p2, unsigned long m2) { |
| 276 | unsigned long mask; |
| 277 | |
| 278 | mask= m1&m2; |
| 279 | return (p1 & mask) == (p2 & mask); |
| 280 | } |
| 281 | |
| 282 | static void addrnet_mustdiffer(const char *w1, unsigned long p1, unsigned long m1, |
| 283 | const char *w2, unsigned long p2, unsigned long m2) { |
| 284 | if (!addrnet_overlap(p1,m1,p2,m2)) return; |
| 285 | badusage("%s %08lx/%08lx overlaps/clashes with %s %08lx/%08lx", |
| 286 | w1,p1,m1, w2,p2,m2); |
| 287 | } |
| 288 | |
| 289 | static unsigned long eat_addr(const char **argp, const char *what, |
| 290 | const char *endchars, int *endchar_r) { |
| 291 | char whatbuf[100]; |
| 292 | unsigned long rv; |
| 293 | int i; |
| 294 | |
| 295 | for (rv=0, i=0; |
| 296 | i<4; |
| 297 | i++) { |
| 298 | rv <<= 8; |
| 299 | sprintf(whatbuf,"%s byte #%d",what,i); |
| 300 | rv |= eat_number(argp,whatbuf, 0,255, i<3 ? "." : endchars, endchar_r); |
| 301 | } |
| 302 | |
| 303 | return rv; |
| 304 | } |
| 305 | |
| 306 | static void eat_prefixmask(const char **argp, const char *what, |
| 307 | const char *endchars, int *endchar_r, |
| 308 | unsigned long *prefix_r, unsigned long *mask_r, int *len_r) { |
| 309 | /* mask_r and len_r may be 0 */ |
| 310 | char whatbuf[100]; |
| 311 | int len; |
| 312 | unsigned long prefix, mask; |
| 313 | |
| 314 | prefix= eat_addr(argp,what, "/",0); |
| 315 | sprintf(whatbuf,"%s length",what); |
| 316 | len= eat_number(argp,whatbuf, 0,32, endchars,endchar_r); |
| 317 | |
| 318 | mask= len ? (~0UL << (32-len)) : 0UL; |
| 319 | if (prefix & ~mask) badusage("%s prefix %08lx not fully contained in mask %08lx", |
| 320 | what,prefix,mask); |
| 321 | *prefix_r= prefix; |
| 322 | if (mask_r) *mask_r= mask; |
| 323 | if (len_r) *len_r= len; |
| 324 | } |
| 325 | |
| 326 | static int addrnet_isin(unsigned long prefix, unsigned long mask, |
| 327 | unsigned long mprefix, unsigned long mmask) { |
| 328 | return !(~mask & mmask) && (prefix & mmask) == mprefix; |
| 329 | } |
| 330 | |
| 331 | /* Totally hideous algorithm for parsing the config file lines. |
| 332 | * For each config file line, we first see if its gid applies. If not |
| 333 | * we skip it. Otherwise, we do |
| 334 | * permit_begin |
| 335 | * which sets <foo>pming to 1 |
| 336 | * for each range. <foo>pming may be 0 if we've determined that |
| 337 | * this line does not apply to <foo>. |
| 338 | * permit_range |
| 339 | * which calls permit_range_thing for each <foo> |
| 340 | * which checks to see if <foo> is inside the relevant |
| 341 | * range (for +) or overlaps it (for -) and updates |
| 342 | * <foo>allow and <foo>pming. |
| 343 | */ |
| 344 | |
| 345 | static void permit_begin(void) { |
| 346 | int i; |
| 347 | |
| 348 | localpming= peerpming= 1; |
| 349 | for (i=0; i<nexroutes; i++) exroutes[i].pming= 1; |
| 350 | } |
| 351 | |
| 352 | static void permit_range_thing(unsigned long tprefix, unsigned long tmask, |
| 353 | const char *what, int *tallow, int *tpming, |
| 354 | unsigned long pprefix, unsigned long pmask, |
| 355 | int plus, int *any) { |
| 356 | if (plus) { |
| 357 | if (!addrnet_isin(tprefix,tmask, pprefix,pmask)) return; |
| 358 | if (*tpming) *tallow= 1; |
| 359 | } else { |
| 360 | if (!addrnet_overlap(tprefix,tmask, pprefix,pmask)) return; |
| 361 | *tpming= 0; |
| 362 | } |
| 363 | if (!proto) printf(" %c%s", plus?'+':'-', what); |
| 364 | *any= 1; |
| 365 | } |
| 366 | |
| 367 | static void permit_range(unsigned long prefix, unsigned long mask, |
| 368 | int plus, int localonly) { |
| 369 | int i, any; |
| 370 | char idbuf[40]; |
| 371 | |
| 372 | assert(!(prefix & ~mask)); |
| 373 | any= 0; |
| 374 | |
| 375 | permit_range_thing(localaddr,~0UL,"local", &localallow,&localpming, |
| 376 | prefix,mask, plus,&any); |
| 377 | |
| 378 | if (!localonly) { |
| 379 | permit_range_thing(peeraddr,~0UL, "peer-addr", &peerallow,&peerpming, |
| 380 | prefix,mask, plus,&any); |
| 381 | for (i=0; i<nexroutes; i++) { |
| 382 | sprintf(idbuf,"route#%d",i); |
| 383 | permit_range_thing(exroutes[i].prefix,exroutes[i].mask, idbuf, |
| 384 | &exroutes[i].allow,&exroutes[i].pming, |
| 385 | prefix,mask, plus,&any); |
| 386 | } |
| 387 | } |
| 388 | if (!proto) |
| 389 | if (!any) fputs(" nothing",stdout); |
| 390 | } |
| 391 | |
| 392 | static void pconfig(const char *configstr, int truncated); |
| 393 | |
| 394 | static void pfile(const char *filename) { |
| 395 | FILE *file; |
| 396 | char buf[PATH_MAX]; |
| 397 | int l, truncated, c; |
| 398 | struct pplace npp, *cpp; |
| 399 | |
| 400 | for (cpp=cpplace; cpp; cpp=cpp->parent) { |
| 401 | if (!strcmp(cpp->filename,filename)) |
| 402 | badusage("recursive configuration file `%s'",filename); |
| 403 | } |
| 404 | |
| 405 | file= fopen(filename,"r"); |
| 406 | if (!file) |
| 407 | badusage("cannot open configuration file `%s': %s", filename, strerror(errno)); |
| 408 | |
| 409 | if (!proto) printf("config file `%s':\n",filename); |
| 410 | |
| 411 | npp.parent= cpplace; |
| 412 | npp.filename= filename; |
| 413 | npp.lineno= 0; |
| 414 | cpplace= &npp; |
| 415 | |
| 416 | while (fgets(buf, sizeof(buf), file)) { |
| 417 | npp.lineno++; |
| 418 | l= strlen(buf); |
| 419 | if (!l) continue; |
| 420 | |
| 421 | truncated= (buf[l-1] != '\n'); |
| 422 | while (l>0 && isspace((unsigned char) buf[l-1])) l--; |
| 423 | if (!l) continue; |
| 424 | buf[l]= 0; |
| 425 | |
| 426 | if (truncated) { |
| 427 | while ((c= getc(file)) != EOF && c != '\n'); |
| 428 | if (c == EOF) break; |
| 429 | } |
| 430 | |
| 431 | pconfig(buf,truncated); |
| 432 | } |
| 433 | if (ferror(file)) |
| 434 | badusage("failed while reading configuration file: %s", strerror(errno)); |
| 435 | |
| 436 | cpplace= npp.parent; |
| 437 | } |
| 438 | |
| 439 | static void pconfig(const char *configstr, int truncated) { |
| 440 | unsigned long fgid, tgid, pprefix, pmask; |
| 441 | int plen, localonly, plus, rangeix, delim; |
| 442 | char ptxt[ATXTLEN]; |
| 443 | char whattxt[100]; |
| 444 | const char *gidlist; |
| 445 | |
| 446 | switch (configstr[0]) { |
| 447 | case '*': |
| 448 | permit_begin(); |
| 449 | permit_range(0UL,0UL,1,0); |
| 450 | return; |
| 451 | |
| 452 | case '#': |
| 453 | return; |
| 454 | |
| 455 | case '/': case '.': |
| 456 | if (truncated) badusage("filename too long (`%.100s...')",configstr); |
| 457 | pfile(configstr); |
| 458 | return; |
| 459 | |
| 460 | default: |
| 461 | if (!isdigit((unsigned char)configstr[0])) |
| 462 | badusage("unknown configuration directive"); |
| 463 | |
| 464 | fgid= eat_number(&configstr,"gid", 0,gidmaxval, ",",0); |
| 465 | |
| 466 | if (!proto) printf(" %5lu", fgid); |
| 467 | |
| 468 | gidlist= getenv("USERV_GID"); |
| 469 | if (!gidlist) fatal("USERV_GID not set"); |
| 470 | for (;;) { |
| 471 | if (!gidlist) { |
| 472 | if (!proto) printf(" no matching gid\n"); |
| 473 | return; |
| 474 | } |
| 475 | tgid= eat_number(&gidlist,"userv-gid", 0,gidmaxval, " ",0); |
| 476 | if (tgid == fgid) break; |
| 477 | } |
| 478 | |
| 479 | if (configstr[0] == '=') { |
| 480 | localonly= 1; |
| 481 | configstr++; |
| 482 | } else { |
| 483 | localonly= 0; |
| 484 | } |
| 485 | |
| 486 | permit_begin(); |
| 487 | |
| 488 | rangeix= 0; |
| 489 | plus= 1; |
| 490 | switch (configstr[0]) { |
| 491 | case '-': plus= 0; /* fall through */ |
| 492 | case '+': configstr++; |
| 493 | default:; |
| 494 | } |
| 495 | |
| 496 | for (;;) { |
| 497 | sprintf(whattxt, "%s-prefix#%d", |
| 498 | plus ? "permitted" : "notpermitted", |
| 499 | rangeix); |
| 500 | eat_prefixmask(&configstr,whattxt, ",+-",&delim, |
| 501 | &pprefix,&pmask,&plen); |
| 502 | if (!configstr && truncated) |
| 503 | badusage("gid,prefix/len,... spec too long"); |
| 504 | |
| 505 | if (!proto) |
| 506 | printf(" %c%s/%d:", plus?'+':'-',ip2txt(pprefix,ptxt), plen); |
| 507 | |
| 508 | permit_range(pprefix,pmask,plus,localonly); |
| 509 | if (delim==',') break; |
| 510 | |
| 511 | plus= delim=='-' ? 0 : 1; |
| 512 | rangeix++; |
| 513 | } |
| 514 | |
| 515 | putchar('\n'); |
| 516 | return; |
| 517 | } |
| 518 | } |
| 519 | |
| 520 | static void checkallow(int allow, const char *what, |
| 521 | const char *prefixtxt, const char *masktxt) { |
| 522 | if (allow) return; |
| 523 | fprintf(stderr,"userv-ipif service: access denied for %s, %s/%s\n", |
| 524 | what, prefixtxt, masktxt); |
| 525 | allallow= 0; |
| 526 | } |
| 527 | |
| 528 | static void parseargs(int argc, const char *const *argv) { |
| 529 | unsigned long routeaddr, routemask; |
| 530 | const char *carg; |
| 531 | const char *const *cprotop; |
| 532 | int i; |
| 533 | char erwhatbuf[100], erwhatbuf2[100]; |
| 534 | |
| 535 | if (argc < NARGS+1) { badusage("too few arguments"); } |
| 536 | if (argc > NARGS+1) { badusage("too many arguments"); } |
| 537 | |
| 538 | configstr= *++argv; |
| 539 | |
| 540 | carg= *++argv; |
| 541 | if (strcmp(carg,"--")) badusage("separator argument `--' not found, got `%s'",carg); |
| 542 | |
| 543 | carg= *++argv; |
| 544 | localaddr= eat_addr(&carg,"local-addr", ",",0); |
| 545 | peeraddr= eat_addr(&carg,"peer-addr", ",",0); |
| 546 | mtu= eat_number(&carg,"mtu", 576,65536, ",",0); |
| 547 | localallow= peerallow= 0; |
| 548 | |
| 549 | if (!strcmp(carg,"debug")) { |
| 550 | proto= 0; |
| 551 | } else { |
| 552 | for (cprotop= protos_ok; |
| 553 | (proto= *cprotop) && strcmp(proto,carg); |
| 554 | cprotop++); |
| 555 | if (!proto) fatal("invalid protocol"); |
| 556 | } |
| 557 | |
| 558 | addrnet_mustdiffer("local-addr",localaddr,~0UL, "peer-addr",peeraddr,~0UL); |
| 559 | |
| 560 | carg= *++argv; |
| 561 | if (strcmp(carg,"-")) { |
| 562 | for (nexroutes=0; |
| 563 | carg && *carg; |
| 564 | nexroutes++) { |
| 565 | if (nexroutes == MAXEXROUTES) |
| 566 | fatal("too many extra routes (only %d allowed)",MAXEXROUTES); |
| 567 | sprintf(erwhatbuf,"route#%d",nexroutes); |
| 568 | |
| 569 | eat_prefixmask(&carg,erwhatbuf, ",",0, &routeaddr,&routemask,0); |
| 570 | if (routemask == ~0UL) { |
| 571 | addrnet_mustdiffer(erwhatbuf,routeaddr,routemask, "local-addr",localaddr,~0UL); |
| 572 | addrnet_mustdiffer(erwhatbuf,routeaddr,routemask, "peer-addr",peeraddr,~0UL); |
| 573 | } |
| 574 | for (i=0; i<nexroutes; i++) { |
| 575 | sprintf(erwhatbuf2,"route#%d",i); |
| 576 | addrnet_mustdiffer(erwhatbuf,routeaddr,routemask, |
| 577 | erwhatbuf2,exroutes[i].prefix,exroutes[i].mask); |
| 578 | } |
| 579 | exroutes[nexroutes].prefix= routeaddr; |
| 580 | exroutes[nexroutes].mask= routemask; |
| 581 | exroutes[nexroutes].allow= 0; |
| 582 | ip2txt(routeaddr,exroutes[nexroutes].prefixtxt); |
| 583 | ip2txt(routemask,exroutes[nexroutes].masktxt); |
| 584 | } |
| 585 | } |
| 586 | |
| 587 | ip2txt(localaddr,localtxt); |
| 588 | ip2txt(peeraddr,peertxt); |
| 589 | } |
| 590 | |
| 591 | static void checkpermit(void) { |
| 592 | int i; |
| 593 | char erwhatbuf[100]; |
| 594 | |
| 595 | allallow= 1; |
| 596 | checkallow(localallow,"local-addr", localtxt,"32"); |
| 597 | checkallow(peerallow,"peer-addr", peertxt,"32"); |
| 598 | for (i=0; i<nexroutes; i++) { |
| 599 | sprintf(erwhatbuf, "route#%d", i); |
| 600 | checkallow(exroutes[i].allow, erwhatbuf, exroutes[i].prefixtxt, exroutes[i].masktxt); |
| 601 | } |
| 602 | if (!allallow) fatal("access denied"); |
| 603 | } |
| 604 | |
| 605 | static void dumpdebug(void) __attribute__((noreturn)); |
| 606 | static void dumpdebug(void) { |
| 607 | int i; |
| 608 | char erwhatbuf[100]; |
| 609 | |
| 610 | printf("protocol: debug\n" |
| 611 | "local: %08lx == %s\n" |
| 612 | "peer: %08lx == %s\n" |
| 613 | "mtu: %ld\n" |
| 614 | "routes: %d\n", |
| 615 | localaddr, localtxt, |
| 616 | peeraddr, peertxt, |
| 617 | mtu, |
| 618 | nexroutes); |
| 619 | for (i=0; i<nexroutes; i++) { |
| 620 | sprintf(erwhatbuf, "route#%d:", i); |
| 621 | printf("%-9s %08lx/%08lx == %s/%s\n", |
| 622 | erwhatbuf, |
| 623 | exroutes[i].prefix, exroutes[i].mask, |
| 624 | exroutes[i].prefixtxt, exroutes[i].masktxt); |
| 625 | } |
| 626 | if (ferror(stdout) || fclose(stdout)) sysfatal("flush stdout"); |
| 627 | exit(0); |
| 628 | } |
| 629 | |
| 630 | |
| 631 | static int task(const char *desc) { |
| 632 | pid_t pid, pidr; |
| 633 | int status; |
| 634 | |
| 635 | pid= fork(); |
| 636 | if (pid == (pid_t)-1) sysfatal("fork for task"); |
| 637 | if (!pid) return 1; |
| 638 | |
| 639 | for (;;) { |
| 640 | pidr= waitpid(pid,&status,0); |
| 641 | if (pidr!=(pid_t)-1) break; |
| 642 | if (errno==EINTR) continue; |
| 643 | sysfatal("waitpid for task"); |
| 644 | } |
| 645 | assert(pidr==pid); |
| 646 | |
| 647 | if (WIFEXITED(status)) { |
| 648 | if (WEXITSTATUS(status)) |
| 649 | fatal("userv-ipif service: %s exited with error exit status %d\n", |
| 650 | desc, WEXITSTATUS(status)); |
| 651 | } else if (WIFSIGNALED(status)) { |
| 652 | fatal("userv-ipif service: %s died due to signal %s%s\n", |
| 653 | desc, strsignal(WTERMSIG(status)), |
| 654 | WCOREDUMP(status) ? " (core dumped)" : ""); |
| 655 | } else { |
| 656 | fatal("userv-ipif service: %s unexpectedly terminated" |
| 657 | " with unknown status code %d\n", desc, status); |
| 658 | } |
| 659 | |
| 660 | return 0; |
| 661 | } |
| 662 | |
| 663 | static void createif(void) { |
| 664 | static const char ifnamepat[]= "userv%d"; |
| 665 | struct ifreq ifr; |
| 666 | int r; |
| 667 | |
| 668 | memset(&ifr,0,sizeof(ifr)); |
| 669 | ifr.ifr_flags= IFF_TUN | IFF_NO_PI; |
| 670 | |
| 671 | assert(sizeof(ifr.ifr_name) >= sizeof(ifnamepat)); |
| 672 | strcpy(ifr.ifr_name, ifnamepat); |
| 673 | |
| 674 | tunfd= open("/dev/net/tun", O_RDWR); |
| 675 | if (!tunfd) sysfatal("open /dev/net/tun"); |
| 676 | |
| 677 | r= fcntl(tunfd, F_GETFD); |
| 678 | if (r==-1) sysfatal("fcntl(tunfd,F_GETFD)"); |
| 679 | r= fcntl(tunfd, F_SETFD, r|FD_CLOEXEC); |
| 680 | if (r==-1) sysfatal("fcntl(tunfd,F_SETFD,|FD_CLOEXEC)"); |
| 681 | |
| 682 | r= ioctl(tunfd, TUNSETIFF, (void*)&ifr); |
| 683 | if (r) sysfatal("ioctl TUNSETIFF"); |
| 684 | |
| 685 | /* ifr.ifr_name might not be null-terminated. crazy abi. */ |
| 686 | ifname= malloc(sizeof(ifr.ifr_name)+1); |
| 687 | if (!ifname) sysfatal("malloc for interface name"); |
| 688 | memcpy(ifname, ifr.ifr_name, sizeof(ifr.ifr_name)); |
| 689 | ifname[sizeof(ifr.ifr_name)]= 0; |
| 690 | } |
| 691 | |
| 692 | static void netconfigure(void) { |
| 693 | char mtutxt[100]; |
| 694 | int i; |
| 695 | |
| 696 | if (task("ifconfig")) { |
| 697 | sprintf(mtutxt,"%lu",mtu); |
| 698 | |
| 699 | execlp("ifconfig", "ifconfig", ifname, localtxt, |
| 700 | "netmask","255.255.255.255", "pointopoint",peertxt, "-broadcast", |
| 701 | "mtu",mtutxt, "up", (char*)0); |
| 702 | sysfatal("cannot exec ifconfig"); |
| 703 | } |
| 704 | |
| 705 | for (i=0; i<nexroutes; i++) { |
| 706 | if (task("route")) { |
| 707 | execlp("route","route", "add", "-net",exroutes[i].prefixtxt, |
| 708 | "netmask",exroutes[i].masktxt, |
| 709 | "gw",peertxt, "dev",ifname, (char*)0); |
| 710 | sysfatal("cannot exec route (for route)"); |
| 711 | } |
| 712 | } |
| 713 | } |
| 714 | |
| 715 | static void setnonblock(int fd) { |
| 716 | int r; |
| 717 | r= fcntl(fd,F_GETFL); |
| 718 | if (r==-1) sysfatal("fcntl F_GETFL"); |
| 719 | r= fcntl(fd,F_SETFL, r|O_NONBLOCK); |
| 720 | if (r==-1) sysfatal("fcntl F_SETFL O_NONBLOCK"); |
| 721 | } |
| 722 | |
| 723 | static void rx_packet(const uint8_t *packet, int len) { |
| 724 | if (!len) |
| 725 | return; |
| 726 | for (;;) { |
| 727 | int r= write(tunfd, packet, len); |
| 728 | if (r<0) { |
| 729 | if (errno==EINTR) continue; |
| 730 | if (errno==EAGAIN || errno==ENOMEM) return; /* oh well */ |
| 731 | sysfatal("error writing packet to tun (transmitting)"); |
| 732 | } |
| 733 | assert(r==len); |
| 734 | return; |
| 735 | } |
| 736 | } |
| 737 | |
| 738 | static int output_waiting, input_waiting; |
| 739 | |
| 740 | #define SLIP_END 0300 |
| 741 | #define SLIP_ESC 0333 |
| 742 | #define SLIP_ESC_END 0334 |
| 743 | #define SLIP_ESC_ESC 0335 |
| 744 | |
| 745 | static void more_rx_data(uint8_t *input_buf, uint8_t *output_buf) { |
| 746 | /* we make slip_data never contain continuation of a packet */ |
| 747 | /* input_buf is passed as a parameter since it's in copydata's stack frame */ |
| 748 | static int scanned; |
| 749 | static int output_len; |
| 750 | |
| 751 | uint8_t *op= output_buf + output_len; |
| 752 | const uint8_t *ip= input_buf + scanned; |
| 753 | const uint8_t *ip_end= input_buf + input_waiting; |
| 754 | int eaten= 0; |
| 755 | |
| 756 | for (;;) { |
| 757 | if (ip>=ip_end) break; |
| 758 | uint8_t c= *ip++; |
| 759 | if (c==SLIP_END) { |
| 760 | rx_packet(output_buf, op-output_buf); |
| 761 | op= output_buf; |
| 762 | eaten= ip - input_buf; |
| 763 | continue; |
| 764 | } |
| 765 | if (c==SLIP_ESC) { |
| 766 | if (ip>=ip_end) { /* rescan this when there's more */ ip--; break; } |
| 767 | c= *ip++; |
| 768 | if (c==SLIP_ESC_END) c=SLIP_END; |
| 769 | else if (c==SLIP_ESC_ESC) c=SLIP_ESC; |
| 770 | else fatal("unexpected byte 0%o after SLIP_ESC",c); |
| 771 | } |
| 772 | if (op == output_buf+mtu) |
| 773 | fatal("SLIP packet exceeds mtu"); |
| 774 | *op++= c; |
| 775 | } |
| 776 | |
| 777 | output_len= op - output_buf; |
| 778 | scanned= ip - input_buf; |
| 779 | |
| 780 | input_waiting -= eaten; |
| 781 | memmove(input_buf, input_buf+eaten, input_waiting); |
| 782 | scanned -= eaten; |
| 783 | } |
| 784 | |
| 785 | static void tx_packet(uint8_t *output_buf, const uint8_t *ip, int inlen) { |
| 786 | /* output_buf is passed as a parameter since it's in copydata's stack frame */ |
| 787 | assert(!output_waiting); |
| 788 | uint8_t *op= output_buf; |
| 789 | |
| 790 | *op++= SLIP_END; |
| 791 | while (inlen-- >0) { |
| 792 | uint8_t c= *ip++; |
| 793 | if (c==SLIP_END) { *op++= SLIP_ESC; *op++= SLIP_ESC_END; } |
| 794 | else if (c==SLIP_ESC) { *op++= SLIP_ESC; *op++= SLIP_ESC_ESC; } |
| 795 | else *op++= c; |
| 796 | } |
| 797 | *op++= SLIP_END; |
| 798 | assert(op <= output_buf + mtu*2+2); |
| 799 | |
| 800 | output_waiting= op - output_buf; |
| 801 | } |
| 802 | |
| 803 | static void copydata(void) __attribute__((noreturn)); |
| 804 | static void copydata(void) { |
| 805 | uint8_t output_buf[mtu*2+2]; |
| 806 | uint8_t input_buf[mtu*2+2]; |
| 807 | uint8_t rx_packet_buf[mtu]; |
| 808 | |
| 809 | int r, i; |
| 810 | |
| 811 | struct pollfd polls[3]; |
| 812 | memset(polls, 0, sizeof(polls)); |
| 813 | |
| 814 | polls[0].fd= 0; polls[0].events= POLLIN; |
| 815 | polls[1].fd= 1; |
| 816 | polls[2].fd= tunfd; |
| 817 | |
| 818 | /* We don't do flow control on input packets; instead, we just throw |
| 819 | * away ones which the kernel doesn't accept. So we always poll for |
| 820 | * those. |
| 821 | * |
| 822 | * Output packets we buffer, so we poll only as appropriate for those. |
| 823 | */ |
| 824 | |
| 825 | /* Start by transmitting one END byte to say we're ready. */ |
| 826 | output_buf[0]= SLIP_END; |
| 827 | output_waiting= 1; |
| 828 | |
| 829 | for (;;) { |
| 830 | if (output_waiting) { |
| 831 | r= write(1, output_buf, output_waiting); |
| 832 | if (r<0) { |
| 833 | if (errno==EINTR) continue; |
| 834 | if (errno!=EAGAIN) |
| 835 | sysfatal("error writing SLIP output (packets being received)"); |
| 836 | } else { |
| 837 | assert(r>0); |
| 838 | output_waiting -= r; |
| 839 | memmove(output_buf, output_buf+r, output_waiting); |
| 840 | } |
| 841 | } |
| 842 | if (output_waiting) { |
| 843 | polls[1].events |= POLLOUT; |
| 844 | polls[2].events &= ~POLLIN; |
| 845 | } else { |
| 846 | polls[1].events &= ~POLLOUT; |
| 847 | polls[2].events |= POLLIN; |
| 848 | } |
| 849 | r= poll(polls,3,-1); |
| 850 | |
| 851 | if (r<0) { |
| 852 | if (errno==EINTR) continue; |
| 853 | sysfatal("poll() failed"); |
| 854 | } |
| 855 | assert(r>0); /* we used an infinite timeout */ |
| 856 | |
| 857 | for (i=0; i<sizeof(polls)/sizeof(polls[0]); i++) |
| 858 | if (polls[i].revents & ~polls[i].events) |
| 859 | fatal("unexpected revents 0x%x for fd=%d", |
| 860 | polls[i].revents, polls[i].fd); |
| 861 | |
| 862 | if (polls[0].events & POLLIN) { |
| 863 | int want= sizeof(input_buf) - input_waiting; |
| 864 | if (want<0) fatal("incoming packet necessarily exceeds MTU"); |
| 865 | r= read(0, input_buf + input_waiting, want); |
| 866 | if (r>0) { |
| 867 | input_waiting += r; |
| 868 | assert(input_waiting <= sizeof(input_buf)); |
| 869 | more_rx_data(input_buf, rx_packet_buf); |
| 870 | } else if (r==0) { |
| 871 | terminate(0); |
| 872 | } else { |
| 873 | if (!(errno==EINTR || errno==EAGAIN)) |
| 874 | sysfatal("error reading input SLIP data (packets to transmit)"); |
| 875 | } |
| 876 | } |
| 877 | |
| 878 | /* We handle what would be (polls[1].events & POLLOUT) above, |
| 879 | * unconditionally. That eliminates the need to poll in the usual case */ |
| 880 | |
| 881 | if (polls[2].events & POLLIN) { |
| 882 | uint8_t packet_buf[mtu]; |
| 883 | r= read(tunfd, packet_buf, mtu); |
| 884 | if (r>0) { |
| 885 | tx_packet(output_buf, packet_buf, r); |
| 886 | } else { |
| 887 | assert(r<0); |
| 888 | if (!(errno==EAGAIN || errno==EWOULDBLOCK)) |
| 889 | sysfatal("error reading packet (being transmitted) from tun"); |
| 890 | } |
| 891 | } |
| 892 | } |
| 893 | } |
| 894 | |
| 895 | int main(int argc, const char *const *argv) { |
| 896 | parseargs(argc,argv); |
| 897 | pconfig(configstr,0); |
| 898 | checkpermit(); |
| 899 | if (!proto) dumpdebug(); |
| 900 | |
| 901 | createif(); |
| 902 | netconfigure(); |
| 903 | setnonblock(tunfd); |
| 904 | setnonblock(0); |
| 905 | setnonblock(1); |
| 906 | copydata(); |
| 907 | } |