1 /* 2 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 3 * Use is subject to license terms. 4 */ 5 6 #pragma ident "%Z%%M% %I% %E% SMI" 7 8 /* 9 * General skeleton for adding options to the access control language. The 10 * features offered by this module are documented in the hosts_options(5) 11 * manual page (source file: hosts_options.5, "nroff -man" format). 12 * 13 * Notes and warnings for those who want to add features: 14 * 15 * In case of errors, abort options processing and deny access. There are too 16 * many irreversible side effects to make error recovery feasible. For 17 * example, it makes no sense to continue after we have already changed the 18 * userid. 19 * 20 * In case of errors, do not terminate the process: the routines might be 21 * called from a long-running daemon that should run forever. Instead, call 22 * tcpd_jump() which does a non-local goto back into the hosts_access() 23 * routine. 24 * 25 * In case of severe errors, use clean_exit() instead of directly calling 26 * exit(), or the inetd may loop on an UDP request. 27 * 28 * In verification mode (for example, with the "tcpdmatch" command) the 29 * "dry_run" flag is set. In this mode, an option function should just "say" 30 * what it is going to do instead of really doing it. 31 * 32 * Some option functions do not return (for example, the twist option passes 33 * control to another program). In verification mode (dry_run flag is set) 34 * such options should clear the "dry_run" flag to inform the caller of this 35 * course of action. 36 */ 37 38 #ifndef lint 39 static char sccsid[] = "@(#) options.c 1.17 96/02/11 17:01:31"; 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 <stdlib.h> 52 #include <unistd.h> 53 #include <syslog.h> 54 #include <pwd.h> 55 #include <grp.h> 56 #include <ctype.h> 57 #include <setjmp.h> 58 #include <string.h> 59 60 #ifndef MAXPATHNAMELEN 61 #define MAXPATHNAMELEN BUFSIZ 62 #endif 63 64 /* Local stuff. */ 65 66 #include "tcpd.h" 67 68 /* Options runtime support. */ 69 70 int dry_run = 0; /* flag set in verification mode */ 71 extern jmp_buf tcpd_buf; /* tcpd_jump() support */ 72 73 /* Options parser support. */ 74 75 static char whitespace_eq[] = "= \t\r\n"; 76 #define whitespace (whitespace_eq + 1) 77 78 static char *get_field(); /* chew :-delimited field off string */ 79 static char *chop_string(); /* strip leading and trailing blanks */ 80 81 /* List of functions that implement the options. Add yours here. */ 82 83 static void user_option(); /* execute "user name.group" option */ 84 static void group_option(); /* execute "group name" option */ 85 static void umask_option(); /* execute "umask mask" option */ 86 static void linger_option(); /* execute "linger time" option */ 87 static void keepalive_option(); /* execute "keepalive" option */ 88 static void spawn_option(); /* execute "spawn command" option */ 89 static void twist_option(); /* execute "twist command" option */ 90 static void rfc931_option(); /* execute "rfc931" option */ 91 static void setenv_option(); /* execute "setenv name value" */ 92 static void nice_option(); /* execute "nice" option */ 93 static void severity_option(); /* execute "severity value" */ 94 static void allow_option(); /* execute "allow" option */ 95 static void deny_option(); /* execute "deny" option */ 96 static void banners_option(); /* execute "banners path" option */ 97 98 /* Structure of the options table. */ 99 100 struct option { 101 char *name; /* keyword name, case is ignored */ 102 void (*func) (); /* function that does the real work */ 103 int flags; /* see below... */ 104 }; 105 106 #define NEED_ARG (1<<1) /* option requires argument */ 107 #define USE_LAST (1<<2) /* option must be last */ 108 #define OPT_ARG (1<<3) /* option has optional argument */ 109 #define EXPAND_ARG (1<<4) /* do %x expansion on argument */ 110 111 #define need_arg(o) ((o)->flags & NEED_ARG) 112 #define opt_arg(o) ((o)->flags & OPT_ARG) 113 #define permit_arg(o) ((o)->flags & (NEED_ARG | OPT_ARG)) 114 #define use_last(o) ((o)->flags & USE_LAST) 115 #define expand_arg(o) ((o)->flags & EXPAND_ARG) 116 117 /* List of known keywords. Add yours here. */ 118 119 static struct option option_table[] = { 120 "user", user_option, NEED_ARG, 121 "group", group_option, NEED_ARG, 122 "umask", umask_option, NEED_ARG, 123 "linger", linger_option, NEED_ARG, 124 "keepalive", keepalive_option, 0, 125 "spawn", spawn_option, NEED_ARG | EXPAND_ARG, 126 "twist", twist_option, NEED_ARG | EXPAND_ARG | USE_LAST, 127 "rfc931", rfc931_option, OPT_ARG, 128 "setenv", setenv_option, NEED_ARG | EXPAND_ARG, 129 "nice", nice_option, OPT_ARG, 130 "severity", severity_option, NEED_ARG, 131 "allow", allow_option, USE_LAST, 132 "deny", deny_option, USE_LAST, 133 "banners", banners_option, NEED_ARG, 134 0, 135 }; 136 137 /* process_options - process access control options */ 138 139 void process_options(options, request) 140 char *options; 141 struct request_info *request; 142 { 143 char *key; 144 char *value; 145 char *curr_opt; 146 char *next_opt; 147 struct option *op; 148 char bf[BUFSIZ]; 149 150 for (curr_opt = get_field(options); curr_opt; curr_opt = next_opt) { 151 next_opt = get_field((char *) 0); 152 153 /* 154 * Separate the option into name and value parts. For backwards 155 * compatibility we ignore exactly one '=' between name and value. 156 */ 157 curr_opt = chop_string(curr_opt); 158 if (*(value = curr_opt + strcspn(curr_opt, whitespace_eq))) { 159 if (*value != '=') { 160 *value++ = 0; 161 value += strspn(value, whitespace); 162 } 163 if (*value == '=') { 164 *value++ = 0; 165 value += strspn(value, whitespace); 166 } 167 } 168 if (*value == 0) 169 value = 0; 170 key = curr_opt; 171 172 /* 173 * Disallow missing option names (and empty option fields). 174 */ 175 if (*key == 0) 176 tcpd_jump("missing option name"); 177 178 /* 179 * Lookup the option-specific info and do some common error checks. 180 * Delegate option-specific processing to the specific functions. 181 */ 182 183 for (op = option_table; op->name && STR_NE(op->name, key); op++) 184 /* VOID */ ; 185 if (op->name == 0) 186 tcpd_jump("bad option name: \"%s\"", key); 187 if (!value && need_arg(op)) 188 tcpd_jump("option \"%s\" requires value", key); 189 if (value && !permit_arg(op)) 190 tcpd_jump("option \"%s\" requires no value", key); 191 if (next_opt && use_last(op)) 192 tcpd_jump("option \"%s\" must be at end", key); 193 if (value && expand_arg(op)) 194 value = chop_string(percent_x(bf, sizeof(bf), value, request)); 195 if (hosts_access_verbose) 196 syslog(LOG_DEBUG, "option: %s %s", key, value ? value : ""); 197 (*(op->func)) (value, request); 198 } 199 } 200 201 /* allow_option - grant access */ 202 203 /* ARGSUSED */ 204 205 static void allow_option(value, request) 206 char *value; 207 struct request_info *request; 208 { 209 longjmp(tcpd_buf, AC_PERMIT); 210 } 211 212 /* deny_option - deny access */ 213 214 /* ARGSUSED */ 215 216 static void deny_option(value, request) 217 char *value; 218 struct request_info *request; 219 { 220 longjmp(tcpd_buf, AC_DENY); 221 } 222 223 /* banners_option - expand %<char>, terminate each line with CRLF */ 224 225 static void banners_option(value, request) 226 char *value; 227 struct request_info *request; 228 { 229 char path[MAXPATHNAMELEN]; 230 char ibuf[BUFSIZ]; 231 char obuf[2 * BUFSIZ]; 232 struct stat st; 233 int ch; 234 FILE *fp; 235 236 sprintf(path, "%s/%s", value, eval_daemon(request)); 237 if ((fp = fopen(path, "r")) != 0) { 238 while ((ch = fgetc(fp)) == 0) 239 write(request->fd, "", 1); 240 ungetc(ch, fp); 241 while (fgets(ibuf, sizeof(ibuf) - 1, fp)) { 242 if (split_at(ibuf, '\n')) 243 strcat(ibuf, "\r\n"); 244 percent_x(obuf, sizeof(obuf), ibuf, request); 245 write(request->fd, obuf, strlen(obuf)); 246 } 247 fclose(fp); 248 } else if (stat(value, &st) < 0) { 249 tcpd_warn("%s: %m", value); 250 } 251 } 252 253 /* group_option - switch group id */ 254 255 /* ARGSUSED */ 256 257 static void group_option(value, request) 258 char *value; 259 struct request_info *request; 260 { 261 struct group *grp; 262 struct group *getgrnam(); 263 264 if ((grp = getgrnam(value)) == 0) 265 tcpd_jump("unknown group: \"%s\"", value); 266 endgrent(); 267 268 if (dry_run == 0 && setgid(grp->gr_gid)) 269 tcpd_jump("setgid(%s): %m", value); 270 } 271 272 /* user_option - switch user id */ 273 274 /* ARGSUSED */ 275 276 static void user_option(value, request) 277 char *value; 278 struct request_info *request; 279 { 280 struct passwd *pwd; 281 struct passwd *getpwnam(); 282 char *group; 283 284 if ((group = split_at(value, '.')) != 0) 285 group_option(group, request); 286 if ((pwd = getpwnam(value)) == 0) 287 tcpd_jump("unknown user: \"%s\"", value); 288 endpwent(); 289 290 if (dry_run == 0 && setuid(pwd->pw_uid)) 291 tcpd_jump("setuid(%s): %m", value); 292 } 293 294 /* umask_option - set file creation mask */ 295 296 /* ARGSUSED */ 297 298 static void umask_option(value, request) 299 char *value; 300 struct request_info *request; 301 { 302 unsigned mask; 303 char junk; 304 305 if (sscanf(value, "%o%c", &mask, &junk) != 1 || (mask & 0777) != mask) 306 tcpd_jump("bad umask value: \"%s\"", value); 307 (void) umask(mask); 308 } 309 310 /* spawn_option - spawn a shell command and wait */ 311 312 /* ARGSUSED */ 313 314 static void spawn_option(value, request) 315 char *value; 316 struct request_info *request; 317 { 318 if (dry_run == 0) 319 shell_cmd(value); 320 } 321 322 /* linger_option - set the socket linger time (Marc Boucher <marc@cam.org>) */ 323 324 /* ARGSUSED */ 325 326 static void linger_option(value, request) 327 char *value; 328 struct request_info *request; 329 { 330 struct linger linger; 331 char junk; 332 333 if (sscanf(value, "%d%c", &linger.l_linger, &junk) != 1 334 || linger.l_linger < 0) 335 tcpd_jump("bad linger value: \"%s\"", value); 336 if (dry_run == 0) { 337 linger.l_onoff = (linger.l_linger != 0); 338 if (setsockopt(request->fd, SOL_SOCKET, SO_LINGER, (char *) &linger, 339 sizeof(linger)) < 0) 340 tcpd_warn("setsockopt SO_LINGER %d: %m", linger.l_linger); 341 } 342 } 343 344 /* keepalive_option - set the socket keepalive option */ 345 346 /* ARGSUSED */ 347 348 static void keepalive_option(value, request) 349 char *value; 350 struct request_info *request; 351 { 352 static int on = 1; 353 354 if (dry_run == 0 && setsockopt(request->fd, SOL_SOCKET, SO_KEEPALIVE, 355 (char *) &on, sizeof(on)) < 0) 356 tcpd_warn("setsockopt SO_KEEPALIVE: %m"); 357 } 358 359 /* nice_option - set nice value */ 360 361 /* ARGSUSED */ 362 363 static void nice_option(value, request) 364 char *value; 365 struct request_info *request; 366 { 367 int niceval = 10; 368 char junk; 369 370 if (value != 0 && sscanf(value, "%d%c", &niceval, &junk) != 1) 371 tcpd_jump("bad nice value: \"%s\"", value); 372 if (dry_run == 0 && nice(niceval) < 0) 373 tcpd_warn("nice(%d): %m", niceval); 374 } 375 376 /* twist_option - replace process by shell command */ 377 378 static void twist_option(value, request) 379 char *value; 380 struct request_info *request; 381 { 382 char *error; 383 384 if (dry_run != 0) { 385 dry_run = 0; 386 } else { 387 if (resident > 0) 388 tcpd_jump("twist option in resident process"); 389 390 syslog(deny_severity, "twist %s to %s", eval_client(request), value); 391 392 /* Before switching to the shell, set up stdin, stdout and stderr. */ 393 394 #define maybe_dup2(from, to) ((from == to) ? to : (close(to), dup(from))) 395 396 if (maybe_dup2(request->fd, 0) != 0 || 397 maybe_dup2(request->fd, 1) != 1 || 398 maybe_dup2(request->fd, 2) != 2) { 399 error = "twist_option: dup: %m"; 400 } else { 401 if (request->fd > 2) 402 close(request->fd); 403 (void) execl("/bin/sh", "sh", "-c", value, (char *) 0); 404 error = "twist_option: /bin/sh: %m"; 405 } 406 407 /* Something went wrong: we MUST terminate the process. */ 408 409 tcpd_warn(error); 410 clean_exit(request); 411 } 412 } 413 414 /* rfc931_option - look up remote user name */ 415 416 static void rfc931_option(value, request) 417 char *value; 418 struct request_info *request; 419 { 420 int timeout; 421 char junk; 422 423 if (value != 0) { 424 if (sscanf(value, "%d%c", &timeout, &junk) != 1 || timeout <= 0) 425 tcpd_jump("bad rfc931 timeout: \"%s\"", value); 426 rfc931_timeout = timeout; 427 } 428 (void) eval_user(request); 429 } 430 431 /* setenv_option - set environment variable */ 432 433 /* ARGSUSED */ 434 435 static void setenv_option(value, request) 436 char *value; 437 struct request_info *request; 438 { 439 extern int setenv(const char *, const char *, int); 440 char *var_value; 441 442 if (*(var_value = value + strcspn(value, whitespace))) 443 *var_value++ = 0; 444 if (setenv(chop_string(value), chop_string(var_value), 1)) 445 tcpd_jump("memory allocation failure"); 446 } 447 448 /* 449 * The severity option goes last because it comes with a huge amount of ugly 450 * #ifdefs and tables. 451 */ 452 453 struct syslog_names { 454 char *name; 455 int value; 456 }; 457 458 static struct syslog_names log_fac[] = { 459 #ifdef LOG_KERN 460 "kern", LOG_KERN, 461 #endif 462 #ifdef LOG_USER 463 "user", LOG_USER, 464 #endif 465 #ifdef LOG_MAIL 466 "mail", LOG_MAIL, 467 #endif 468 #ifdef LOG_DAEMON 469 "daemon", LOG_DAEMON, 470 #endif 471 #ifdef LOG_AUTH 472 "auth", LOG_AUTH, 473 #endif 474 #ifdef LOG_LPR 475 "lpr", LOG_LPR, 476 #endif 477 #ifdef LOG_NEWS 478 "news", LOG_NEWS, 479 #endif 480 #ifdef LOG_UUCP 481 "uucp", LOG_UUCP, 482 #endif 483 #ifdef LOG_CRON 484 "cron", LOG_CRON, 485 #endif 486 #ifdef LOG_LOCAL0 487 "local0", LOG_LOCAL0, 488 #endif 489 #ifdef LOG_LOCAL1 490 "local1", LOG_LOCAL1, 491 #endif 492 #ifdef LOG_LOCAL2 493 "local2", LOG_LOCAL2, 494 #endif 495 #ifdef LOG_LOCAL3 496 "local3", LOG_LOCAL3, 497 #endif 498 #ifdef LOG_LOCAL4 499 "local4", LOG_LOCAL4, 500 #endif 501 #ifdef LOG_LOCAL5 502 "local5", LOG_LOCAL5, 503 #endif 504 #ifdef LOG_LOCAL6 505 "local6", LOG_LOCAL6, 506 #endif 507 #ifdef LOG_LOCAL7 508 "local7", LOG_LOCAL7, 509 #endif 510 0, 511 }; 512 513 static struct syslog_names log_sev[] = { 514 #ifdef LOG_EMERG 515 "emerg", LOG_EMERG, 516 #endif 517 #ifdef LOG_ALERT 518 "alert", LOG_ALERT, 519 #endif 520 #ifdef LOG_CRIT 521 "crit", LOG_CRIT, 522 #endif 523 #ifdef LOG_ERR 524 "err", LOG_ERR, 525 #endif 526 #ifdef LOG_WARNING 527 "warning", LOG_WARNING, 528 #endif 529 #ifdef LOG_NOTICE 530 "notice", LOG_NOTICE, 531 #endif 532 #ifdef LOG_INFO 533 "info", LOG_INFO, 534 #endif 535 #ifdef LOG_DEBUG 536 "debug", LOG_DEBUG, 537 #endif 538 0, 539 }; 540 541 /* severity_map - lookup facility or severity value */ 542 543 static int severity_map(table, name) 544 struct syslog_names *table; 545 char *name; 546 { 547 struct syslog_names *t; 548 549 for (t = table; t->name; t++) 550 if (STR_EQ(t->name, name)) 551 return (t->value); 552 tcpd_jump("bad syslog facility or severity: \"%s\"", name); 553 /* NOTREACHED */ 554 } 555 556 /* severity_option - change logging severity for this event (Dave Mitchell) */ 557 558 /* ARGSUSED */ 559 560 static void severity_option(value, request) 561 char *value; 562 struct request_info *request; 563 { 564 char *level = split_at(value, '.'); 565 566 allow_severity = deny_severity = level ? 567 severity_map(log_fac, value) | severity_map(log_sev, level) : 568 severity_map(log_sev, value); 569 } 570 571 /* get_field - return pointer to next field in string */ 572 573 static char *get_field(string) 574 char *string; 575 { 576 static char *last = ""; 577 char *src; 578 char *dst; 579 char *ret; 580 int ch; 581 582 /* 583 * This function returns pointers to successive fields within a given 584 * string. ":" is the field separator; warn if the rule ends in one. It 585 * replaces a "\:" sequence by ":", without treating the result of 586 * substitution as field terminator. A null argument means resume search 587 * where the previous call terminated. This function destroys its 588 * argument. 589 * 590 * Work from explicit source or from memory. While processing \: we 591 * overwrite the input. This way we do not have to maintain buffers for 592 * copies of input fields. 593 */ 594 595 src = dst = ret = (string ? string : last); 596 if (src[0] == 0) 597 return (0); 598 599 while (ch = *src) { 600 if (ch == ':') { 601 if (*++src == 0) 602 tcpd_warn("rule ends in \":\""); 603 break; 604 } 605 if (ch == '\\' && src[1] == ':') 606 src++; 607 *dst++ = *src++; 608 } 609 last = src; 610 *dst = 0; 611 return (ret); 612 } 613 614 /* chop_string - strip leading and trailing blanks from string */ 615 616 static char *chop_string(string) 617 register char *string; 618 { 619 char *start = 0; 620 char *end; 621 char *cp; 622 623 for (cp = string; *cp; cp++) { 624 if (!isspace(*cp)) { 625 if (start == 0) 626 start = cp; 627 end = cp; 628 } 629 } 630 return (start ? (end[1] = 0, start) : cp); 631 } 632