1 /* $NetBSD: options.c,v 1.16 2012/03/22 22:59:43 joerg Exp $ */ 2 3 /* 4 * General skeleton for adding options to the access control language. The 5 * features offered by this module are documented in the hosts_options(5) 6 * manual page (source file: hosts_options.5, "nroff -man" format). 7 * 8 * Notes and warnings for those who want to add features: 9 * 10 * In case of errors, abort options processing and deny access. There are too 11 * many irreversible side effects to make error recovery feasible. For 12 * example, it makes no sense to continue after we have already changed the 13 * userid. 14 * 15 * In case of errors, do not terminate the process: the routines might be 16 * called from a long-running daemon that should run forever. Instead, call 17 * tcpd_jump() which does a non-local goto back into the hosts_access() 18 * routine. 19 * 20 * In case of severe errors, use clean_exit() instead of directly calling 21 * exit(), or the inetd may loop on an UDP request. 22 * 23 * In verification mode (for example, with the "tcpdmatch" command) the 24 * "dry_run" flag is set. In this mode, an option function should just "say" 25 * what it is going to do instead of really doing it. 26 * 27 * Some option functions do not return (for example, the twist option passes 28 * control to another program). In verification mode (dry_run flag is set) 29 * such options should clear the "dry_run" flag to inform the caller of this 30 * course of action. 31 */ 32 33 #include <sys/cdefs.h> 34 #ifndef lint 35 #if 0 36 static char sccsid[] = "@(#) options.c 1.17 96/02/11 17:01:31"; 37 #else 38 __RCSID("$NetBSD: options.c,v 1.16 2012/03/22 22:59:43 joerg Exp $"); 39 #endif 40 #endif 41 42 /* System libraries. */ 43 44 #include <sys/types.h> 45 #include <sys/param.h> 46 #include <sys/socket.h> 47 #include <sys/stat.h> 48 #include <netinet/in.h> 49 #include <netdb.h> 50 #include <stdio.h> 51 #include <syslog.h> 52 #include <unistd.h> 53 #include <stdlib.h> 54 #include <pwd.h> 55 #include <grp.h> 56 #include <ctype.h> 57 #include <setjmp.h> 58 #include <string.h> 59 60 /* Local stuff. */ 61 62 #include "tcpd.h" 63 64 /* Options runtime support. */ 65 66 int dry_run = 0; /* flag set in verification mode */ 67 extern jmp_buf tcpd_buf; /* tcpd_jump() support */ 68 69 /* Options parser support. */ 70 71 static char whitespace_eq[] = "= \t\r\n"; 72 #define whitespace (whitespace_eq + 1) 73 74 static char *get_field /* chew :-delimited field off string */ 75 (char *); 76 static char *chop_string /* strip leading and trailing blanks */ 77 (char *); 78 struct syslog_names; 79 static int severity_map 80 (const struct syslog_names *, char *); 81 82 /* List of functions that implement the options. Add yours here. */ 83 84 static void user_option /* execute "user name.group" option */ 85 (char *, struct request_info *); 86 static void group_option /* execute "group name" option */ 87 (char *, struct request_info *); 88 static void umask_option /* execute "umask mask" option */ 89 (char *, struct request_info *); 90 static void linger_option /* execute "linger time" option */ 91 (char *, struct request_info *); 92 static void keepalive_option /* execute "keepalive" option */ 93 (char *, struct request_info *); 94 static void spawn_option /* execute "spawn command" option */ 95 (char *, struct request_info *); 96 static void twist_option /* execute "twist command" option */ 97 (char *, struct request_info *); 98 static void rfc931_option /* execute "rfc931" option */ 99 (char *, struct request_info *); 100 static void setenv_option /* execute "setenv name value" */ 101 (char *, struct request_info *); 102 static void nice_option /* execute "nice" option */ 103 (char *, struct request_info *); 104 static void severity_option /* execute "severity value" */ 105 (char *, struct request_info *); 106 __dead static void allow_option /* execute "allow" option */ 107 (char *, struct request_info *); 108 __dead static void deny_option /* execute "deny" option */ 109 (char *, struct request_info *); 110 static void banners_option /* execute "banners path" option */ 111 (char *, struct request_info *); 112 113 /* Structure of the options table. */ 114 115 struct option { 116 const char *name; /* keyword name, case is ignored */ 117 void (*func) /* function that does the real work */ 118 (char *, struct request_info *); 119 int flags; /* see below... */ 120 }; 121 122 #define NEED_ARG (1<<1) /* option requires argument */ 123 #define USE_LAST (1<<2) /* option must be last */ 124 #define OPT_ARG (1<<3) /* option has optional argument */ 125 #define EXPAND_ARG (1<<4) /* do %x expansion on argument */ 126 127 #define need_arg(o) ((o)->flags & NEED_ARG) 128 #define opt_arg(o) ((o)->flags & OPT_ARG) 129 #define permit_arg(o) ((o)->flags & (NEED_ARG | OPT_ARG)) 130 #define use_last(o) ((o)->flags & USE_LAST) 131 #define expand_arg(o) ((o)->flags & EXPAND_ARG) 132 133 /* List of known keywords. Add yours here. */ 134 135 static struct option option_table[] = { 136 { "user", user_option, NEED_ARG }, 137 { "group", group_option, NEED_ARG }, 138 { "umask", umask_option, NEED_ARG }, 139 { "linger", linger_option, NEED_ARG }, 140 { "keepalive", keepalive_option, 0 }, 141 { "spawn", spawn_option, NEED_ARG | EXPAND_ARG }, 142 { "twist", twist_option, NEED_ARG | EXPAND_ARG | USE_LAST }, 143 { "rfc931", rfc931_option, OPT_ARG }, 144 { "setenv", setenv_option, NEED_ARG | EXPAND_ARG }, 145 { "nice", nice_option, OPT_ARG }, 146 { "severity", severity_option, NEED_ARG }, 147 { "allow", allow_option, USE_LAST }, 148 { "deny", deny_option, USE_LAST }, 149 { "banners", banners_option, NEED_ARG }, 150 { NULL, NULL, 0 } 151 }; 152 153 /* process_options - process access control options */ 154 155 void 156 process_options(char *options, struct request_info *request) 157 { 158 char *key; 159 char *value; 160 char *curr_opt; 161 char *next_opt; 162 struct option *op; 163 char bf[BUFSIZ]; 164 165 for (curr_opt = get_field(options); curr_opt; curr_opt = next_opt) { 166 next_opt = get_field((char *) 0); 167 168 /* 169 * Separate the option into name and value parts. For backwards 170 * compatibility we ignore exactly one '=' between name and value. 171 */ 172 curr_opt = chop_string(curr_opt); 173 if (*(value = curr_opt + strcspn(curr_opt, whitespace_eq))) { 174 if (*value != '=') { 175 *value++ = 0; 176 value += strspn(value, whitespace); 177 } 178 if (*value == '=') { 179 *value++ = 0; 180 value += strspn(value, whitespace); 181 } 182 } 183 if (*value == 0) 184 value = 0; 185 key = curr_opt; 186 187 /* 188 * Disallow missing option names (and empty option fields). 189 */ 190 if (*key == 0) 191 tcpd_jump("missing option name"); 192 193 /* 194 * Lookup the option-specific info and do some common error checks. 195 * Delegate option-specific processing to the specific functions. 196 */ 197 198 for (op = option_table; op->name && STR_NE(op->name, key); op++) 199 /* VOID */ ; 200 if (op->name == 0) 201 tcpd_jump("bad option name: \"%s\"", key); 202 if (!value && need_arg(op)) 203 tcpd_jump("option \"%s\" requires value", key); 204 if (value && !permit_arg(op)) 205 tcpd_jump("option \"%s\" requires no value", key); 206 if (next_opt && use_last(op)) 207 tcpd_jump("option \"%s\" must be at end", key); 208 if (value && expand_arg(op)) 209 value = chop_string(percent_x(bf, sizeof(bf), value, request)); 210 if (hosts_access_verbose) 211 syslog(LOG_DEBUG, "option: %s %s", key, value ? value : ""); 212 (*(op->func)) (value, request); 213 } 214 } 215 216 /* allow_option - grant access */ 217 218 /* ARGSUSED */ 219 220 static void 221 allow_option(char *value, struct request_info *request) 222 { 223 longjmp(tcpd_buf, AC_PERMIT); 224 } 225 226 /* deny_option - deny access */ 227 228 /* ARGSUSED */ 229 230 static void 231 deny_option(char *value, struct request_info *request) 232 { 233 longjmp(tcpd_buf, AC_DENY); 234 } 235 236 /* banners_option - expand %<char>, terminate each line with CRLF */ 237 238 static void 239 banners_option(char *value, struct request_info *request) 240 { 241 char path[MAXPATHLEN]; 242 char ibuf[BUFSIZ]; 243 char obuf[2 * BUFSIZ]; 244 struct stat st; 245 int ch; 246 FILE *fp; 247 248 (void)snprintf(path, sizeof path, "%s/%s", value, eval_daemon(request)); 249 if ((fp = fopen(path, "r")) != 0) { 250 while ((ch = fgetc(fp)) == 0) 251 write(request->fd, "", 1); 252 ungetc(ch, fp); 253 while (fgets(ibuf, sizeof(ibuf) - 2, fp)) { 254 if (split_at(ibuf, '\n')) 255 strcat(ibuf, "\r\n"); /* XXX strcat is safe */ 256 percent_x(obuf, sizeof(obuf), ibuf, request); 257 write(request->fd, obuf, strlen(obuf)); 258 } 259 fclose(fp); 260 } else if (stat(value, &st) < 0) { 261 tcpd_warn("%s: %m", value); 262 } 263 } 264 265 /* group_option - switch group id */ 266 267 /* ARGSUSED */ 268 269 static void 270 group_option(char *value, struct request_info *request) 271 { 272 struct group grs, *grp; 273 char grbuf[1024]; 274 275 (void)getgrnam_r(value, &grs, grbuf, sizeof(grbuf), &grp); 276 if (grp == NULL) 277 tcpd_jump("unknown group: \"%s\"", value); 278 279 if (dry_run == 0 && setgid(grp->gr_gid)) 280 tcpd_jump("setgid(%s): %m", value); 281 } 282 283 /* user_option - switch user id */ 284 285 /* ARGSUSED */ 286 287 static void 288 user_option(char *value, struct request_info *request) 289 { 290 struct passwd *pwd, pws; 291 char *group; 292 char pwbuf[1024]; 293 294 if ((group = split_at(value, '.')) != 0) 295 group_option(group, request); 296 (void)getpwnam_r(value, &pws, pwbuf, sizeof(pwbuf), &pwd); 297 if (pwd == NULL) 298 tcpd_jump("unknown user: \"%s\"", value); 299 300 if (dry_run == 0 && setuid(pwd->pw_uid)) 301 tcpd_jump("setuid(%s): %m", value); 302 } 303 304 /* umask_option - set file creation mask */ 305 306 /* ARGSUSED */ 307 308 static void 309 umask_option(char *value, struct request_info *request) 310 { 311 unsigned mask; 312 char junk; 313 314 if (sscanf(value, "%o%c", &mask, &junk) != 1 || (mask & 0777) != mask) 315 tcpd_jump("bad umask value: \"%s\"", value); 316 (void) umask(mask); 317 } 318 319 /* spawn_option - spawn a shell command and wait */ 320 321 /* ARGSUSED */ 322 323 static void 324 spawn_option(char *value, struct request_info *request) 325 { 326 if (dry_run == 0) 327 shell_cmd(value); 328 } 329 330 /* linger_option - set the socket linger time (Marc Boucher <marc (at) cam.org>) */ 331 332 /* ARGSUSED */ 333 334 static void 335 linger_option(char *value, struct request_info *request) 336 { 337 struct linger linger; 338 char junk; 339 340 if (sscanf(value, "%d%c", &linger.l_linger, &junk) != 1 341 || linger.l_linger < 0) 342 tcpd_jump("bad linger value: \"%s\"", value); 343 if (dry_run == 0) { 344 linger.l_onoff = (linger.l_linger != 0); 345 if (setsockopt(request->fd, SOL_SOCKET, SO_LINGER, (char *) &linger, 346 sizeof(linger)) < 0) 347 tcpd_warn("setsockopt SO_LINGER %d: %m", linger.l_linger); 348 } 349 } 350 351 /* keepalive_option - set the socket keepalive option */ 352 353 /* ARGSUSED */ 354 355 static void 356 keepalive_option(char *value, struct request_info *request) 357 { 358 static int on = 1; 359 360 if (dry_run == 0 && setsockopt(request->fd, SOL_SOCKET, SO_KEEPALIVE, 361 (char *) &on, sizeof(on)) < 0) 362 tcpd_warn("setsockopt SO_KEEPALIVE: %m"); 363 } 364 365 /* nice_option - set nice value */ 366 367 /* ARGSUSED */ 368 369 static void 370 nice_option(char *value, struct request_info *request) 371 { 372 int niceval = 10; 373 char junk; 374 375 if (value != 0 && sscanf(value, "%d%c", &niceval, &junk) != 1) 376 tcpd_jump("bad nice value: \"%s\"", value); 377 if (dry_run == 0 && nice(niceval) < 0) 378 tcpd_warn("nice(%d): %m", niceval); 379 } 380 381 /* twist_option - replace process by shell command */ 382 383 static void 384 twist_option(char *value, struct request_info *request) 385 { 386 if (dry_run != 0) { 387 dry_run = 0; 388 } else { 389 if (resident > 0) 390 tcpd_jump("twist option in resident process"); 391 392 syslog(deny_severity, "twist %s to %s", eval_client(request), value); 393 394 /* Before switching to the shell, set up stdin, stdout and stderr. */ 395 396 #define maybe_dup2(from, to) ((from == to) ? to : (close(to), dup(from))) 397 398 if (maybe_dup2(request->fd, 0) != 0 || 399 maybe_dup2(request->fd, 1) != 1 || 400 maybe_dup2(request->fd, 2) != 2) { 401 tcpd_warn("twist_option: dup: %m"); 402 } else { 403 if (request->fd > 2) 404 close(request->fd); 405 (void) execl("/bin/sh", "sh", "-c", value, (char *) 0); 406 tcpd_warn("twist_option: /bin/sh: %m"); 407 } 408 409 /* Something went wrong: we MUST terminate the process. */ 410 clean_exit(request); 411 } 412 } 413 414 /* rfc931_option - look up remote user name */ 415 416 static void 417 rfc931_option(char *value, struct request_info *request) 418 { 419 int timeout; 420 char junk; 421 422 if (value != 0) { 423 if (sscanf(value, "%d%c", &timeout, &junk) != 1 || timeout <= 0) 424 tcpd_jump("bad rfc931 timeout: \"%s\"", value); 425 rfc931_timeout = timeout; 426 } 427 (void) eval_user(request); 428 } 429 430 /* setenv_option - set environment variable */ 431 432 /* ARGSUSED */ 433 434 static void 435 setenv_option(char *value, struct request_info *request) 436 { 437 char *var_value; 438 439 if (*(var_value = value + strcspn(value, whitespace))) 440 *var_value++ = 0; 441 if (setenv(chop_string(value), chop_string(var_value), 1)) 442 tcpd_jump("memory allocation failure"); 443 } 444 445 /* 446 * The severity option goes last because it comes with a huge amount of ugly 447 * #ifdefs and tables. 448 */ 449 450 struct syslog_names { 451 const char *name; 452 int value; 453 }; 454 455 static const struct syslog_names log_fac[] = { 456 #ifdef LOG_KERN 457 { "kern", LOG_KERN }, 458 #endif 459 #ifdef LOG_USER 460 { "user", LOG_USER }, 461 #endif 462 #ifdef LOG_MAIL 463 { "mail", LOG_MAIL }, 464 #endif 465 #ifdef LOG_DAEMON 466 { "daemon", LOG_DAEMON }, 467 #endif 468 #ifdef LOG_AUTH 469 { "auth", LOG_AUTH }, 470 #endif 471 #ifdef LOG_LPR 472 { "lpr", LOG_LPR }, 473 #endif 474 #ifdef LOG_NEWS 475 { "news", LOG_NEWS }, 476 #endif 477 #ifdef LOG_UUCP 478 { "uucp", LOG_UUCP }, 479 #endif 480 #ifdef LOG_CRON 481 { "cron", LOG_CRON }, 482 #endif 483 #ifdef LOG_AUTHPRIV 484 { "authpriv", LOG_AUTHPRIV }, 485 #endif 486 #ifdef LOG_FTP 487 { "ftp", LOG_FTP }, 488 #endif 489 #ifdef LOG_LOCAL0 490 { "local0", LOG_LOCAL0 }, 491 #endif 492 #ifdef LOG_LOCAL1 493 { "local1", LOG_LOCAL1 }, 494 #endif 495 #ifdef LOG_LOCAL2 496 { "local2", LOG_LOCAL2 }, 497 #endif 498 #ifdef LOG_LOCAL3 499 { "local3", LOG_LOCAL3 }, 500 #endif 501 #ifdef LOG_LOCAL4 502 { "local4", LOG_LOCAL4 }, 503 #endif 504 #ifdef LOG_LOCAL5 505 { "local5", LOG_LOCAL5 }, 506 #endif 507 #ifdef LOG_LOCAL6 508 { "local6", LOG_LOCAL6 }, 509 #endif 510 #ifdef LOG_LOCAL7 511 { "local7", LOG_LOCAL7 }, 512 #endif 513 { NULL, 0 } 514 }; 515 516 static const struct syslog_names log_sev[] = { 517 #ifdef LOG_EMERG 518 { "emerg", LOG_EMERG }, 519 #endif 520 #ifdef LOG_ALERT 521 { "alert", LOG_ALERT }, 522 #endif 523 #ifdef LOG_CRIT 524 { "crit", LOG_CRIT }, 525 #endif 526 #ifdef LOG_ERR 527 { "err", LOG_ERR }, 528 #endif 529 #ifdef LOG_WARNING 530 { "warning", LOG_WARNING }, 531 #endif 532 #ifdef LOG_NOTICE 533 { "notice", LOG_NOTICE }, 534 #endif 535 #ifdef LOG_INFO 536 { "info", LOG_INFO }, 537 #endif 538 #ifdef LOG_DEBUG 539 { "debug", LOG_DEBUG }, 540 #endif 541 { NULL, 0 } 542 }; 543 544 /* severity_map - lookup facility or severity value */ 545 546 static int 547 severity_map(const struct syslog_names *table, char *name) 548 { 549 const struct syslog_names *t; 550 551 for (t = table; t->name; t++) 552 if (STR_EQ(t->name, name)) 553 return (t->value); 554 tcpd_jump("bad syslog facility or severity: \"%s\"", name); 555 /* NOTREACHED */ 556 return -1; 557 } 558 559 /* severity_option - change logging severity for this event (Dave Mitchell) */ 560 561 /* ARGSUSED */ 562 563 static void 564 severity_option(char *value, struct request_info *request) 565 { 566 char *level = split_at(value, '.'); 567 568 allow_severity = deny_severity = level ? 569 severity_map(log_fac, value) | severity_map(log_sev, level) : 570 severity_map(log_sev, value); 571 } 572 573 /* get_field - return pointer to next field in string */ 574 575 static char * 576 get_field(char *string) 577 { 578 static char nul = '\0'; 579 static char *last = &nul; 580 char *src; 581 char *dst; 582 char *ret; 583 int ch; 584 585 /* 586 * This function returns pointers to successive fields within a given 587 * string. ":" is the field separator; warn if the rule ends in one. It 588 * replaces a "\:" sequence by ":", without treating the result of 589 * substitution as field terminator. A null argument means resume search 590 * where the previous call terminated. This function destroys its 591 * argument. 592 * 593 * Work from explicit source or from memory. While processing \: we 594 * overwrite the input. This way we do not have to maintain buffers for 595 * copies of input fields. 596 */ 597 598 src = dst = ret = (string ? string : last); 599 if (src[0] == 0) 600 return (0); 601 602 while ((ch = *src) != '\0') { 603 if (ch == ':') { 604 if (*++src == 0) 605 tcpd_warn("rule ends in \":\""); 606 break; 607 } 608 if (ch == '\\' && src[1] == ':') 609 src++; 610 *dst++ = *src++; 611 } 612 last = src; 613 *dst = 0; 614 return (ret); 615 } 616 617 /* chop_string - strip leading and trailing blanks from string */ 618 619 static char * 620 chop_string(register char *string) 621 { 622 char *start = NULL; 623 char *end = NULL; 624 char *cp; 625 626 for (cp = string; *cp; cp++) { 627 if (!isspace((unsigned char) *cp)) { 628 if (start == 0) 629 start = cp; 630 end = cp; 631 } 632 } 633 return (start ? (end[1] = 0, start) : cp); 634 } 635
Indexes created Sun Sep 21 20:09:37 GMT 2025