1 /* 2 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 3 * Use is subject to license terms. 4 */ 5 6 /* 7 * General skeleton for adding options to the access control language. The 8 * features offered by this module are documented in the hosts_options(5) 9 * manual page (source file: hosts_options.5, "nroff -man" format). 10 * 11 * Notes and warnings for those who want to add features: 12 * 13 * In case of errors, abort options processing and deny access. There are too 14 * many irreversible side effects to make error recovery feasible. For 15 * example, it makes no sense to continue after we have already changed the 16 * userid. 17 * 18 * In case of errors, do not terminate the process: the routines might be 19 * called from a long-running daemon that should run forever. Instead, call 20 * tcpd_jump() which does a non-local goto back into the hosts_access() 21 * routine. 22 * 23 * In case of severe errors, use clean_exit() instead of directly calling 24 * exit(), or the inetd may loop on an UDP request. 25 * 26 * In verification mode (for example, with the "tcpdmatch" command) the 27 * "dry_run" flag is set. In this mode, an option function should just "say" 28 * what it is going to do instead of really doing it. 29 * 30 * Some option functions do not return (for example, the twist option passes 31 * control to another program). In verification mode (dry_run flag is set) 32 * such options should clear the "dry_run" flag to inform the caller of this 33 * course of action. 34 */ 35 36 #ifndef lint 37 static char sccsid[] = "@(#) options.c 1.17 96/02/11 17:01:31"; 38 #endif 39 40 /* System libraries. */ 41 42 #include <sys/types.h> 43 #include <sys/param.h> 44 #include <sys/socket.h> 45 #include <sys/stat.h> 46 #include <netinet/in.h> 47 #include <netdb.h> 48 #include <stdio.h> 49 #include <stdlib.h> 50 #include <unistd.h> 51 #include <syslog.h> 52 #include <pwd.h> 53 #include <grp.h> 54 #include <ctype.h> 55 #include <setjmp.h> 56 #include <string.h> 57 58 #ifndef MAXPATHNAMELEN 59 #define MAXPATHNAMELEN BUFSIZ 60 #endif 61 62 /* Local stuff. */ 63 64 #include "tcpd.h" 65 66 /* Options runtime support. */ 67 68 int dry_run = 0; /* flag set in verification mode */ 69 extern jmp_buf tcpd_buf; /* tcpd_jump() support */ 70 71 /* Options parser support. */ 72 73 static char whitespace_eq[] = "= \t\r\n"; 74 #define whitespace (whitespace_eq + 1) 75 76 static char *get_field(); /* chew :-delimited field off string */ 77 static char *chop_string(); /* strip leading and trailing blanks */ 78 79 /* List of functions that implement the options. Add yours here. */ 80 81 static void user_option(); /* execute "user name.group" option */ 82 static void group_option(); /* execute "group name" option */ 83 static void umask_option(); /* execute "umask mask" option */ 84 static void linger_option(); /* execute "linger time" option */ 85 static void keepalive_option(); /* execute "keepalive" option */ 86 static void spawn_option(); /* execute "spawn command" option */ 87 static void twist_option(); /* execute "twist command" option */ 88 static void rfc931_option(); /* execute "rfc931" option */ 89 static void setenv_option(); /* execute "setenv name value" */ 90 static void nice_option(); /* execute "nice" option */ 91 static void severity_option(); /* execute "severity value" */ 92 static void allow_option(); /* execute "allow" option */ 93 static void deny_option(); /* execute "deny" option */ 94 static void banners_option(); /* execute "banners path" option */ 95 96 /* Structure of the options table. */ 97 98 struct option { 99 char *name; /* keyword name, case is ignored */ 100 void (*func) (); /* function that does the real work */ 101 int flags; /* see below... */ 102 }; 103 104 #define NEED_ARG (1<<1) /* option requires argument */ 105 #define USE_LAST (1<<2) /* option must be last */ 106 #define OPT_ARG (1<<3) /* option has optional argument */ 107 #define EXPAND_ARG (1<<4) /* do %x expansion on argument */ 108 109 #define need_arg(o) ((o)->flags & NEED_ARG) 110 #define opt_arg(o) ((o)->flags & OPT_ARG) 111 #define permit_arg(o) ((o)->flags & (NEED_ARG | OPT_ARG)) 112 #define use_last(o) ((o)->flags & USE_LAST) 113 #define expand_arg(o) ((o)->flags & EXPAND_ARG) 114 115 /* List of known keywords. Add yours here. */ 116 117 static struct option option_table[] = { 118 "user", user_option, NEED_ARG, 119 "group", group_option, NEED_ARG, 120 "umask", umask_option, NEED_ARG, 121 "linger", linger_option, NEED_ARG, 122 "keepalive", keepalive_option, 0, 123 "spawn", spawn_option, NEED_ARG | EXPAND_ARG, 124 "twist", twist_option, NEED_ARG | EXPAND_ARG | USE_LAST, 125 "rfc931", rfc931_option, OPT_ARG, 126 "setenv", setenv_option, NEED_ARG | EXPAND_ARG, 127 "nice", nice_option, OPT_ARG, 128 "severity", severity_option, NEED_ARG, 129 "allow", allow_option, USE_LAST, 130 "deny", deny_option, USE_LAST, 131 "banners", banners_option, NEED_ARG, 132 0, 133 }; 134 135 /* process_options - process access control options */ 136 137 void process_options(options, request) 138 char *options; 139 struct request_info *request; 140 { 141 char *key; 142 char *value; 143 char *curr_opt; 144 char *next_opt; 145 struct option *op; 146 char bf[BUFSIZ]; 147 148 for (curr_opt = get_field(options); curr_opt; curr_opt = next_opt) { 149 next_opt = get_field((char *) 0); 150 151 /* 152 * Separate the option into name and value parts. For backwards 153 * compatibility we ignore exactly one '=' between name and value. 154 */ 155 curr_opt = chop_string(curr_opt); 156 if (*(value = curr_opt + strcspn(curr_opt, whitespace_eq))) { 157 if (*value != '=') { 158 *value++ = 0; 159 value += strspn(value, whitespace); 160 } 161 if (*value == '=') { 162 *value++ = 0; 163 value += strspn(value, whitespace); 164 } 165 } 166 if (*value == 0) 167 value = 0; 168 key = curr_opt; 169 170 /* 171 * Disallow missing option names (and empty option fields). 172 */ 173 if (*key == 0) 174 tcpd_jump("missing option name"); 175 176 /* 177 * Lookup the option-specific info and do some common error checks. 178 * Delegate option-specific processing to the specific functions. 179 */ 180 181 for (op = option_table; op->name && STR_NE(op->name, key); op++) 182 /* VOID */ ; 183 if (op->name == 0) 184 tcpd_jump("bad option name: \"%s\"", key); 185 if (!value && need_arg(op)) 186 tcpd_jump("option \"%s\" requires value", key); 187 if (value && !permit_arg(op)) 188 tcpd_jump("option \"%s\" requires no value", key); 189 if (next_opt && use_last(op)) 190 tcpd_jump("option \"%s\" must be at end", key); 191 if (value && expand_arg(op)) 192 value = chop_string(percent_x(bf, sizeof(bf), value, request)); 193 if (hosts_access_verbose) 194 syslog(LOG_DEBUG, "option: %s %s", key, value ? value : ""); 195 (*(op->func)) (value, request); 196 } 197 } 198 199 /* allow_option - grant access */ 200 201 /* ARGSUSED */ 202 203 static void allow_option(value, request) 204 char *value; 205 struct request_info *request; 206 { 207 longjmp(tcpd_buf, AC_PERMIT); 208 } 209 210 /* deny_option - deny access */ 211 212 /* ARGSUSED */ 213 214 static void deny_option(value, request) 215 char *value; 216 struct request_info *request; 217 { 218 longjmp(tcpd_buf, AC_DENY); 219 } 220 221 /* banners_option - expand %<char>, terminate each line with CRLF */ 222 223 static void banners_option(value, request) 224 char *value; 225 struct request_info *request; 226 { 227 char path[MAXPATHNAMELEN]; 228 char ibuf[BUFSIZ]; 229 char obuf[2 * BUFSIZ]; 230 struct stat st; 231 int ch; 232 FILE *fp; 233 234 sprintf(path, "%s/%s", value, eval_daemon(request)); 235 if ((fp = fopen(path, "r")) != 0) { 236 while ((ch = fgetc(fp)) == 0) 237 write(request->fd, "", 1); 238 ungetc(ch, fp); 239 while (fgets(ibuf, sizeof(ibuf) - 1, fp)) { 240 if (split_at(ibuf, '\n')) 241 strcat(ibuf, "\r\n"); 242 percent_x(obuf, sizeof(obuf), ibuf, request); 243 write(request->fd, obuf, strlen(obuf)); 244 } 245 fclose(fp); 246 } else if (stat(value, &st) < 0) { 247 tcpd_warn("%s: %m", value); 248 } 249 } 250 251 /* group_option - switch group id */ 252 253 /* ARGSUSED */ 254 255 static void group_option(value, request) 256 char *value; 257 struct request_info *request; 258 { 259 struct group *grp; 260 struct group *getgrnam(); 261 262 if ((grp = getgrnam(value)) == 0) 263 tcpd_jump("unknown group: \"%s\"", value); 264 endgrent(); 265 266 if (dry_run == 0 && setgid(grp->gr_gid)) 267 tcpd_jump("setgid(%s): %m", value); 268 } 269 270 /* user_option - switch user id */ 271 272 /* ARGSUSED */ 273 274 static void user_option(value, request) 275 char *value; 276 struct request_info *request; 277 { 278 struct passwd *pwd; 279 struct passwd *getpwnam(); 280 char *group; 281 282 if ((group = split_at(value, '.')) != 0) 283 group_option(group, request); 284 if ((pwd = getpwnam(value)) == 0) 285 tcpd_jump("unknown user: \"%s\"", value); 286 endpwent(); 287 288 if (dry_run == 0 && setuid(pwd->pw_uid)) 289 tcpd_jump("setuid(%s): %m", value); 290 } 291 292 /* umask_option - set file creation mask */ 293 294 /* ARGSUSED */ 295 296 static void umask_option(value, request) 297 char *value; 298 struct request_info *request; 299 { 300 unsigned mask; 301 char junk; 302 303 if (sscanf(value, "%o%c", &mask, &junk) != 1 || (mask & 0777) != mask) 304 tcpd_jump("bad umask value: \"%s\"", value); 305 (void) umask(mask); 306 } 307 308 /* spawn_option - spawn a shell command and wait */ 309 310 /* ARGSUSED */ 311 312 static void spawn_option(value, request) 313 char *value; 314 struct request_info *request; 315 { 316 if (dry_run == 0) 317 shell_cmd(value); 318 } 319 320 /* linger_option - set the socket linger time (Marc Boucher <marc@cam.org>) */ 321 322 /* ARGSUSED */ 323 324 static void linger_option(value, request) 325 char *value; 326 struct request_info *request; 327 { 328 struct linger linger; 329 char junk; 330 331 if (sscanf(value, "%d%c", &linger.l_linger, &junk) != 1 332 || linger.l_linger < 0) 333 tcpd_jump("bad linger value: \"%s\"", value); 334 if (dry_run == 0) { 335 linger.l_onoff = (linger.l_linger != 0); 336 if (setsockopt(request->fd, SOL_SOCKET, SO_LINGER, (char *) &linger, 337 sizeof(linger)) < 0) 338 tcpd_warn("setsockopt SO_LINGER %d: %m", linger.l_linger); 339 } 340 } 341 342 /* keepalive_option - set the socket keepalive option */ 343 344 /* ARGSUSED */ 345 346 static void keepalive_option(value, request) 347 char *value; 348 struct request_info *request; 349 { 350 static int on = 1; 351 352 if (dry_run == 0 && setsockopt(request->fd, SOL_SOCKET, SO_KEEPALIVE, 353 (char *) &on, sizeof(on)) < 0) 354 tcpd_warn("setsockopt SO_KEEPALIVE: %m"); 355 } 356 357 /* nice_option - set nice value */ 358 359 /* ARGSUSED */ 360 361 static void nice_option(value, request) 362 char *value; 363 struct request_info *request; 364 { 365 int niceval = 10; 366 char junk; 367 368 if (value != 0 && sscanf(value, "%d%c", &niceval, &junk) != 1) 369 tcpd_jump("bad nice value: \"%s\"", value); 370 if (dry_run == 0 && nice(niceval) < 0) 371 tcpd_warn("nice(%d): %m", niceval); 372 } 373 374 /* twist_option - replace process by shell command */ 375 376 static void twist_option(value, request) 377 char *value; 378 struct request_info *request; 379 { 380 char *error; 381 382 if (dry_run != 0) { 383 dry_run = 0; 384 } else { 385 if (resident > 0) 386 tcpd_jump("twist option in resident process"); 387 388 syslog(deny_severity, "twist %s to %s", eval_client(request), value); 389 390 /* Before switching to the shell, set up stdin, stdout and stderr. */ 391 392 #define maybe_dup2(from, to) ((from == to) ? to : (close(to), dup(from))) 393 394 if (maybe_dup2(request->fd, 0) != 0 || 395 maybe_dup2(request->fd, 1) != 1 || 396 maybe_dup2(request->fd, 2) != 2) { 397 error = "twist_option: dup: %m"; 398 } else { 399 if (request->fd > 2) 400 close(request->fd); 401 (void) execl("/bin/sh", "sh", "-c", value, (char *) 0); 402 error = "twist_option: /bin/sh: %m"; 403 } 404 405 /* Something went wrong: we MUST terminate the process. */ 406 407 tcpd_warn(error); 408 clean_exit(request); 409 } 410 } 411 412 /* rfc931_option - look up remote user name */ 413 414 static void rfc931_option(value, request) 415 char *value; 416 struct request_info *request; 417 { 418 int timeout; 419 char junk; 420 421 if (value != 0) { 422 if (sscanf(value, "%d%c", &timeout, &junk) != 1 || timeout <= 0) 423 tcpd_jump("bad rfc931 timeout: \"%s\"", value); 424 rfc931_timeout = timeout; 425 } 426 (void) eval_user(request); 427 } 428 429 /* setenv_option - set environment variable */ 430 431 /* ARGSUSED */ 432 433 static void setenv_option(value, request) 434 char *value; 435 struct request_info *request; 436 { 437 extern int setenv(const char *, const char *, int); 438 char *var_value; 439 440 if (*(var_value = value + strcspn(value, whitespace))) 441 *var_value++ = 0; 442 if (setenv(chop_string(value), chop_string(var_value), 1)) 443 tcpd_jump("memory allocation failure"); 444 } 445 446 /* 447 * The severity option goes last because it comes with a huge amount of ugly 448 * #ifdefs and tables. 449 */ 450 451 struct syslog_names { 452 char *name; 453 int value; 454 }; 455 456 static struct syslog_names log_fac[] = { 457 #ifdef LOG_KERN 458 "kern", LOG_KERN, 459 #endif 460 #ifdef LOG_USER 461 "user", LOG_USER, 462 #endif 463 #ifdef LOG_MAIL 464 "mail", LOG_MAIL, 465 #endif 466 #ifdef LOG_DAEMON 467 "daemon", LOG_DAEMON, 468 #endif 469 #ifdef LOG_AUTH 470 "auth", LOG_AUTH, 471 #endif 472 #ifdef LOG_LPR 473 "lpr", LOG_LPR, 474 #endif 475 #ifdef LOG_NEWS 476 "news", LOG_NEWS, 477 #endif 478 #ifdef LOG_UUCP 479 "uucp", LOG_UUCP, 480 #endif 481 #ifdef LOG_CRON 482 "cron", LOG_CRON, 483 #endif 484 #ifdef LOG_LOCAL0 485 "local0", LOG_LOCAL0, 486 #endif 487 #ifdef LOG_LOCAL1 488 "local1", LOG_LOCAL1, 489 #endif 490 #ifdef LOG_LOCAL2 491 "local2", LOG_LOCAL2, 492 #endif 493 #ifdef LOG_LOCAL3 494 "local3", LOG_LOCAL3, 495 #endif 496 #ifdef LOG_LOCAL4 497 "local4", LOG_LOCAL4, 498 #endif 499 #ifdef LOG_LOCAL5 500 "local5", LOG_LOCAL5, 501 #endif 502 #ifdef LOG_LOCAL6 503 "local6", LOG_LOCAL6, 504 #endif 505 #ifdef LOG_LOCAL7 506 "local7", LOG_LOCAL7, 507 #endif 508 0, 509 }; 510 511 static struct syslog_names log_sev[] = { 512 #ifdef LOG_EMERG 513 "emerg", LOG_EMERG, 514 #endif 515 #ifdef LOG_ALERT 516 "alert", LOG_ALERT, 517 #endif 518 #ifdef LOG_CRIT 519 "crit", LOG_CRIT, 520 #endif 521 #ifdef LOG_ERR 522 "err", LOG_ERR, 523 #endif 524 #ifdef LOG_WARNING 525 "warning", LOG_WARNING, 526 #endif 527 #ifdef LOG_NOTICE 528 "notice", LOG_NOTICE, 529 #endif 530 #ifdef LOG_INFO 531 "info", LOG_INFO, 532 #endif 533 #ifdef LOG_DEBUG 534 "debug", LOG_DEBUG, 535 #endif 536 0, 537 }; 538 539 /* severity_map - lookup facility or severity value */ 540 541 static int severity_map(table, name) 542 struct syslog_names *table; 543 char *name; 544 { 545 struct syslog_names *t; 546 547 for (t = table; t->name; t++) 548 if (STR_EQ(t->name, name)) 549 return (t->value); 550 tcpd_jump("bad syslog facility or severity: \"%s\"", name); 551 /* NOTREACHED */ 552 } 553 554 /* severity_option - change logging severity for this event (Dave Mitchell) */ 555 556 /* ARGSUSED */ 557 558 static void severity_option(value, request) 559 char *value; 560 struct request_info *request; 561 { 562 char *level = split_at(value, '.'); 563 564 allow_severity = deny_severity = level ? 565 severity_map(log_fac, value) | severity_map(log_sev, level) : 566 severity_map(log_sev, value); 567 } 568 569 /* get_field - return pointer to next field in string */ 570 571 static char *get_field(string) 572 char *string; 573 { 574 static char *last = ""; 575 char *src; 576 char *dst; 577 char *ret; 578 int ch; 579 580 /* 581 * This function returns pointers to successive fields within a given 582 * string. ":" is the field separator; warn if the rule ends in one. It 583 * replaces a "\:" sequence by ":", without treating the result of 584 * substitution as field terminator. A null argument means resume search 585 * where the previous call terminated. This function destroys its 586 * argument. 587 * 588 * Work from explicit source or from memory. While processing \: we 589 * overwrite the input. This way we do not have to maintain buffers for 590 * copies of input fields. 591 */ 592 593 src = dst = ret = (string ? string : last); 594 if (src[0] == 0) 595 return (0); 596 597 while (ch = *src) { 598 if (ch == ':') { 599 if (*++src == 0) 600 tcpd_warn("rule ends in \":\""); 601 break; 602 } 603 if (ch == '\\' && src[1] == ':') 604 src++; 605 *dst++ = *src++; 606 } 607 last = src; 608 *dst = 0; 609 return (ret); 610 } 611 612 /* chop_string - strip leading and trailing blanks from string */ 613 614 static char *chop_string(string) 615 register char *string; 616 { 617 char *start = 0; 618 char *end; 619 char *cp; 620 621 for (cp = string; *cp; cp++) { 622 if (!isspace(*cp)) { 623 if (start == 0) 624 start = cp; 625 end = cp; 626 } 627 } 628 return (start ? (end[1] = 0, start) : cp); 629 } 630