1 /* $OpenBSD: crontab.c,v 1.21 2001/08/11 20:47:14 millert Exp $ */ 2 /* Copyright 1988,1990,1993,1994 by Paul Vixie 3 * All rights reserved 4 */ 5 6 /* 7 * Copyright (c) 1997,2000 by Internet Software Consortium, Inc. 8 * 9 * Permission to use, copy, modify, and distribute this software for any 10 * purpose with or without fee is hereby granted, provided that the above 11 * copyright notice and this permission notice appear in all copies. 12 * 13 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS 14 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES 15 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE 16 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 17 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 18 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 19 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 20 * SOFTWARE. 21 */ 22 23 #if !defined(lint) && !defined(LINT) 24 static char rcsid[] = "$OpenBSD: crontab.c,v 1.21 2001/08/11 20:47:14 millert Exp $"; 25 #endif 26 27 /* crontab - install and manage per-user crontab files 28 * vix 02may87 [RCS has the rest of the log] 29 * vix 26jan87 [original] 30 */ 31 32 #define MAIN_PROGRAM 33 34 #include "cron.h" 35 36 #define NHEADER_LINES 3 37 38 enum opt_t { opt_unknown, opt_list, opt_delete, opt_edit, opt_replace }; 39 40 #if DEBUGGING 41 static char *Options[] = { "???", "list", "delete", "edit", "replace" }; 42 static char *getoptargs = "u:lerx:"; 43 #else 44 static char *getoptargs = "u:ler"; 45 #endif 46 47 static PID_T Pid; 48 static char User[MAX_UNAME], RealUser[MAX_UNAME]; 49 static char Filename[MAX_FNAME], TempFilename[MAX_FNAME]; 50 static FILE *NewCrontab; 51 static int CheckErrorCount; 52 static enum opt_t Option; 53 static struct passwd *pw; 54 static void list_cmd(void), 55 delete_cmd(void), 56 edit_cmd(void), 57 poke_daemon(void), 58 check_error(const char *), 59 parse_args(int c, char *v[]); 60 static int replace_cmd(void); 61 static void clean_turds __P((int)); 62 63 static void 64 usage(const char *msg) { 65 fprintf(stderr, "%s: usage error: %s\n", ProgramName, msg); 66 fprintf(stderr, "usage:\t%s [-u user] file\n", ProgramName); 67 fprintf(stderr, "\t%s [-u user] [ -e | -l | -r ]\n", ProgramName); 68 fprintf(stderr, "\t\t(default operation is replace, per 1003.2)\n"); 69 fprintf(stderr, "\t-e\t(edit user's crontab)\n"); 70 fprintf(stderr, "\t-l\t(list user's crontab)\n"); 71 fprintf(stderr, "\t-r\t(delete user's crontab)\n"); 72 exit(ERROR_EXIT); 73 } 74 75 int 76 main(int argc, char *argv[]) { 77 int exitstatus; 78 79 Pid = getpid(); 80 ProgramName = argv[0]; 81 82 setlocale(LC_ALL, ""); 83 84 #if defined(BSD) 85 setlinebuf(stderr); 86 #endif 87 parse_args(argc, argv); /* sets many globals, opens a file */ 88 set_cron_uid(); 89 set_cron_cwd(); 90 if (!allowed(User)) { 91 fprintf(stderr, 92 "You (%s) are not allowed to use this program (%s)\n", 93 User, ProgramName); 94 fprintf(stderr, "See crontab(1) for more information\n"); 95 log_it(RealUser, Pid, "AUTH", "crontab command not allowed"); 96 exit(ERROR_EXIT); 97 } 98 exitstatus = OK_EXIT; 99 switch (Option) { 100 case opt_list: 101 list_cmd(); 102 break; 103 case opt_delete: 104 delete_cmd(); 105 break; 106 case opt_edit: 107 edit_cmd(); 108 break; 109 case opt_replace: 110 if (replace_cmd() < 0) 111 exitstatus = ERROR_EXIT; 112 break; 113 default: 114 abort(); 115 } 116 exit(0); 117 /*NOTREACHED*/ 118 } 119 120 static void 121 parse_args(int argc, char *argv[]) { 122 int argch; 123 124 if (!(pw = getpwuid(getuid()))) { 125 fprintf(stderr, "%s: your UID isn't in the passwd file.\n", 126 ProgramName); 127 fprintf(stderr, "bailing out.\n"); 128 exit(ERROR_EXIT); 129 } 130 if (strlen(pw->pw_name) >= sizeof User) { 131 fprintf(stderr, "username too long\n"); 132 exit(ERROR_EXIT); 133 } 134 strcpy(User, pw->pw_name); 135 strcpy(RealUser, User); 136 Filename[0] = '\0'; 137 Option = opt_unknown; 138 while (-1 != (argch = getopt(argc, argv, getoptargs))) { 139 switch (argch) { 140 case 'x': 141 if (!set_debug_flags(optarg)) 142 usage("bad debug option"); 143 break; 144 case 'u': 145 if (MY_UID(pw) != ROOT_UID) { 146 fprintf(stderr, 147 "must be privileged to use -u\n"); 148 exit(ERROR_EXIT); 149 } 150 if (!(pw = getpwnam(optarg))) { 151 fprintf(stderr, "%s: user `%s' unknown\n", 152 ProgramName, optarg); 153 exit(ERROR_EXIT); 154 } 155 if (strlen(optarg) >= sizeof User) 156 usage("username too long"); 157 (void) strcpy(User, optarg); 158 break; 159 case 'l': 160 if (Option != opt_unknown) 161 usage("only one operation permitted"); 162 Option = opt_list; 163 break; 164 case 'r': 165 if (Option != opt_unknown) 166 usage("only one operation permitted"); 167 Option = opt_delete; 168 break; 169 case 'e': 170 if (Option != opt_unknown) 171 usage("only one operation permitted"); 172 Option = opt_edit; 173 break; 174 default: 175 usage("unrecognized option"); 176 } 177 } 178 179 endpwent(); 180 181 if (Option != opt_unknown) { 182 if (argv[optind] != NULL) 183 usage("no arguments permitted after this option"); 184 } else { 185 if (argv[optind] != NULL) { 186 Option = opt_replace; 187 if (strlen(argv[optind]) >= sizeof Filename) 188 usage("filename too long"); 189 (void) strcpy (Filename, argv[optind]); 190 } else 191 usage("file name must be specified for replace"); 192 } 193 194 if (Option == opt_replace) { 195 /* we have to open the file here because we're going to 196 * chdir(2) into /var/cron before we get around to 197 * reading the file. 198 */ 199 if (!strcmp(Filename, "-")) 200 NewCrontab = stdin; 201 else { 202 /* relinquish the setuid status of the binary during 203 * the open, lest nonroot users read files they should 204 * not be able to read. we can't use access() here 205 * since there's a race condition. thanks go out to 206 * Arnt Gulbrandsen <agulbra@pvv.unit.no> for spotting 207 * the race. 208 */ 209 210 if (swap_uids() < OK) { 211 perror("swapping uids"); 212 exit(ERROR_EXIT); 213 } 214 if (!(NewCrontab = fopen(Filename, "r"))) { 215 perror(Filename); 216 exit(ERROR_EXIT); 217 } 218 if (swap_uids_back() < OK) { 219 perror("swapping uids back"); 220 exit(ERROR_EXIT); 221 } 222 } 223 } 224 225 Debug(DMISC, ("user=%s, file=%s, option=%s\n", 226 User, Filename, Options[(int)Option])) 227 } 228 229 230 static void 231 list_cmd(void) { 232 char n[MAX_FNAME]; 233 FILE *f; 234 int ch; 235 236 log_it(RealUser, Pid, "LIST", User); 237 if (!glue_strings(n, sizeof n, SPOOL_DIR, User, '/')) { 238 fprintf(stderr, "path too long\n"); 239 exit(ERROR_EXIT); 240 } 241 if (!(f = fopen(n, "r"))) { 242 if (errno == ENOENT) 243 fprintf(stderr, "no crontab for %s\n", User); 244 else 245 perror(n); 246 exit(ERROR_EXIT); 247 } 248 249 /* file is open. copy to stdout, close. 250 */ 251 Set_LineNum(1) 252 while (EOF != (ch = get_char(f))) 253 putchar(ch); 254 fclose(f); 255 } 256 257 static void 258 delete_cmd(void) { 259 char n[MAX_FNAME]; 260 261 log_it(RealUser, Pid, "DELETE", User); 262 if (!glue_strings(n, sizeof n, SPOOL_DIR, User, '/')) { 263 fprintf(stderr, "path too long\n"); 264 exit(ERROR_EXIT); 265 } 266 if (unlink(n) != 0) { 267 if (errno == ENOENT) 268 fprintf(stderr, "no crontab for %s\n", User); 269 else 270 perror(n); 271 exit(ERROR_EXIT); 272 } 273 poke_daemon(); 274 } 275 276 static void 277 check_error(const char *msg) { 278 CheckErrorCount++; 279 fprintf(stderr, "\"%s\":%d: %s\n", Filename, LineNumber-1, msg); 280 } 281 282 static void 283 edit_cmd(void) { 284 char n[MAX_FNAME], q[MAX_TEMPSTR], *editor; 285 FILE *f; 286 int ch, t, x; 287 struct stat statbuf; 288 time_t mtime; 289 off_t size; 290 WAIT_T waiter; 291 PID_T pid, xpid; 292 293 log_it(RealUser, Pid, "BEGIN EDIT", User); 294 if (!glue_strings(n, sizeof n, SPOOL_DIR, User, '/')) { 295 fprintf(stderr, "path too long\n"); 296 exit(ERROR_EXIT); 297 } 298 if (!(f = fopen(n, "r"))) { 299 if (errno != ENOENT) { 300 perror(n); 301 exit(ERROR_EXIT); 302 } 303 fprintf(stderr, "no crontab for %s - using an empty one\n", 304 User); 305 if (!(f = fopen("/dev/null", "r"))) { 306 perror("/dev/null"); 307 exit(ERROR_EXIT); 308 } 309 } 310 311 /* Turn off signals. */ 312 (void)signal(SIGHUP, SIG_IGN); 313 (void)signal(SIGINT, SIG_IGN); 314 (void)signal(SIGQUIT, SIG_IGN); 315 316 if (!glue_strings(Filename, sizeof Filename, _PATH_TMP, 317 "crontab.XXXXXXXXXX", '/')) { 318 fprintf(stderr, "path too long\n"); 319 goto fatal; 320 } 321 if (-1 == (t = mkstemp(Filename))) { 322 perror(Filename); 323 goto fatal; 324 } 325 #ifdef HAS_FCHOWN 326 if (fchown(t, MY_UID(pw), MY_GID(pw)) < 0) { 327 perror("fchown"); 328 goto fatal; 329 } 330 #else 331 if (chown(Filename, MY_UID(pw), MY_GID(pw)) < 0) { 332 perror("chown"); 333 goto fatal; 334 } 335 #endif 336 if (!(NewCrontab = fdopen(t, "r+"))) { 337 perror("fdopen"); 338 goto fatal; 339 } 340 341 Set_LineNum(1) 342 343 /* ignore the top few comments since we probably put them there. 344 */ 345 for (x = 0; x < NHEADER_LINES; x++) { 346 ch = get_char(f); 347 if (EOF == ch) 348 break; 349 if ('#' != ch) { 350 putc(ch, NewCrontab); 351 break; 352 } 353 while (EOF != (ch = get_char(f))) 354 if (ch == '\n') 355 break; 356 if (EOF == ch) 357 break; 358 } 359 360 /* copy the rest of the crontab (if any) to the temp file. 361 */ 362 if (EOF != ch) 363 while (EOF != (ch = get_char(f))) 364 putc(ch, NewCrontab); 365 fclose(f); 366 if (fflush(NewCrontab) < OK) { 367 perror(Filename); 368 exit(ERROR_EXIT); 369 } 370 again: 371 rewind(NewCrontab); 372 if (ferror(NewCrontab)) { 373 fprintf(stderr, "%s: error while writing new crontab to %s\n", 374 ProgramName, Filename); 375 fatal: 376 unlink(Filename); 377 exit(ERROR_EXIT); 378 } 379 if (fstat(t, &statbuf) < 0) { 380 perror("fstat"); 381 goto fatal; 382 } 383 mtime = statbuf.st_mtime; 384 size = statbuf.st_size; 385 386 if (((editor = getenv("VISUAL")) == NULL || *editor == '\0') && 387 ((editor = getenv("EDITOR")) == NULL || *editor == '\0')) { 388 editor = EDITOR; 389 } 390 391 /* we still have the file open. editors will generally rewrite the 392 * original file rather than renaming/unlinking it and starting a 393 * new one; even backup files are supposed to be made by copying 394 * rather than by renaming. if some editor does not support this, 395 * then don't use it. the security problems are more severe if we 396 * close and reopen the file around the edit. 397 */ 398 399 switch (pid = fork()) { 400 case -1: 401 perror("fork"); 402 goto fatal; 403 case 0: 404 /* child */ 405 if (setgid(MY_GID(pw)) < 0) { 406 perror("setgid(getgid())"); 407 exit(ERROR_EXIT); 408 } 409 if (setuid(MY_UID(pw)) < 0) { 410 perror("setuid(getuid())"); 411 exit(ERROR_EXIT); 412 } 413 if (chdir(_PATH_TMP) < 0) { 414 perror(_PATH_TMP); 415 exit(ERROR_EXIT); 416 } 417 if (!glue_strings(q, sizeof q, editor, Filename, ' ')) { 418 fprintf(stderr, "%s: editor command line too long\n", 419 ProgramName); 420 exit(ERROR_EXIT); 421 } 422 execlp(_PATH_BSHELL, _PATH_BSHELL, "-c", q, (char *)NULL); 423 perror(editor); 424 exit(ERROR_EXIT); 425 /*NOTREACHED*/ 426 default: 427 /* parent */ 428 break; 429 } 430 431 /* parent */ 432 for (;;) { 433 xpid = waitpid(pid, &waiter, WUNTRACED); 434 if (xpid == -1) { 435 if (errno != EINTR) 436 fprintf(stderr, "%s: waitpid() failed waiting for PID %ld from \"%s\": %s\n", 437 ProgramName, (long)pid, editor, strerror(errno)); 438 } else if (xpid != pid) { 439 fprintf(stderr, "%s: wrong PID (%ld != %ld) from \"%s\"\n", 440 ProgramName, (long)xpid, (long)pid, editor); 441 goto fatal; 442 } else if (WIFSTOPPED(waiter)) { 443 raise(WSTOPSIG(waiter)); 444 } else if (WIFEXITED(waiter) && WEXITSTATUS(waiter)) { 445 fprintf(stderr, "%s: \"%s\" exited with status %d\n", 446 ProgramName, editor, WEXITSTATUS(waiter)); 447 goto fatal; 448 } else if (WIFSIGNALED(waiter)) { 449 fprintf(stderr, 450 "%s: \"%s\" killed; signal %d (%score dumped)\n", 451 ProgramName, editor, WTERMSIG(waiter), 452 WCOREDUMP(waiter) ?"" :"no "); 453 goto fatal; 454 } else 455 break; 456 } 457 (void)signal(SIGHUP, SIG_DFL); 458 (void)signal(SIGINT, SIG_DFL); 459 (void)signal(SIGQUIT, SIG_DFL); 460 if (fstat(t, &statbuf) < 0) { 461 perror("fstat"); 462 goto fatal; 463 } 464 if (mtime == statbuf.st_mtime && size == statbuf.st_size) { 465 fprintf(stderr, "%s: no changes made to crontab\n", 466 ProgramName); 467 goto remove; 468 } 469 fprintf(stderr, "%s: installing new crontab\n", ProgramName); 470 switch (replace_cmd()) { 471 case 0: 472 break; 473 case -1: 474 for (;;) { 475 printf("Do you want to retry the same edit? "); 476 fflush(stdout); 477 q[0] = '\0'; 478 (void) fgets(q, sizeof q, stdin); 479 switch (islower(q[0]) ? q[0] : tolower(q[0])) { 480 case 'y': 481 goto again; 482 case 'n': 483 goto abandon; 484 default: 485 fprintf(stderr, "Enter Y or N\n"); 486 } 487 } 488 /*NOTREACHED*/ 489 case -2: 490 abandon: 491 fprintf(stderr, "%s: edits left in %s\n", 492 ProgramName, Filename); 493 goto done; 494 default: 495 fprintf(stderr, "%s: panic: bad switch() in replace_cmd()\n", 496 ProgramName); 497 goto fatal; 498 } 499 remove: 500 unlink(Filename); 501 done: 502 log_it(RealUser, Pid, "END EDIT", User); 503 } 504 505 506 /* returns 0 on success 507 * -1 on syntax error 508 * -2 on install error 509 */ 510 static int 511 replace_cmd(void) { 512 char n[MAX_FNAME], envstr[MAX_ENVSTR]; 513 FILE *tmp; 514 int ch, eof, fd; 515 int error = 0; 516 entry *e; 517 time_t now = time(NULL); 518 char **envp = env_init(); 519 struct stat sb; 520 521 if (envp == NULL) { 522 fprintf(stderr, "%s: Cannot allocate memory.\n", ProgramName); 523 return (-2); 524 } 525 if (!glue_strings(TempFilename, sizeof TempFilename, SPOOL_DIR, 526 "tmp.XXXXXXXXXX", '/')) { 527 TempFilename[0] = '\0'; 528 fprintf(stderr, "path too long\n"); 529 return (-2); 530 } 531 if ((fd = mkstemp(TempFilename)) == -1 || !(tmp = fdopen(fd, "w+"))) { 532 perror(TempFilename); 533 if (fd != -1) { 534 close(fd); 535 unlink(TempFilename); 536 } 537 TempFilename[0] = '\0'; 538 return (-2); 539 } 540 541 (void) signal(SIGHUP, clean_turds); 542 (void) signal(SIGINT, clean_turds); 543 (void) signal(SIGQUIT, clean_turds); 544 545 /* write a signature at the top of the file. 546 * 547 * VERY IMPORTANT: make sure NHEADER_LINES agrees with this code. 548 */ 549 fprintf(tmp, "# DO NOT EDIT THIS FILE - edit the master and reinstall.\n"); 550 fprintf(tmp, "# (%s installed on %-24.24s)\n", Filename, ctime(&now)); 551 fprintf(tmp, "# (Cron version -- %s)\n", rcsid); 552 553 /* copy the crontab to the tmp 554 */ 555 rewind(NewCrontab); 556 Set_LineNum(1) 557 while (EOF != (ch = get_char(NewCrontab))) 558 putc(ch, tmp); 559 ftruncate(fileno(tmp), ftell(tmp)); /* XXX redundant with "w+"? */ 560 fflush(tmp); rewind(tmp); 561 562 if (ferror(tmp)) { 563 fprintf(stderr, "%s: error while writing new crontab to %s\n", 564 ProgramName, TempFilename); 565 fclose(tmp); 566 error = -2; 567 goto done; 568 } 569 570 /* check the syntax of the file being installed. 571 */ 572 573 /* BUG: was reporting errors after the EOF if there were any errors 574 * in the file proper -- kludged it by stopping after first error. 575 * vix 31mar87 576 */ 577 Set_LineNum(1 - NHEADER_LINES) 578 CheckErrorCount = 0; eof = FALSE; 579 while (!CheckErrorCount && !eof) { 580 switch (load_env(envstr, tmp)) { 581 case ERR: 582 eof = TRUE; 583 break; 584 case FALSE: 585 e = load_entry(tmp, check_error, pw, envp); 586 if (e) 587 free(e); 588 break; 589 case TRUE: 590 break; 591 } 592 } 593 594 if (CheckErrorCount != 0) { 595 fprintf(stderr, "errors in crontab file, can't install.\n"); 596 fclose(tmp); 597 error = -1; 598 goto done; 599 } 600 601 if (fstat(fileno(tmp), &sb)) 602 sb.st_gid = -1; 603 604 #ifdef HAS_FCHOWN 605 if (fchown(fileno(tmp), ROOT_UID, sb.st_gid) < OK) { 606 perror("fchown"); 607 fclose(tmp); 608 error = -2; 609 goto done; 610 } 611 #else 612 if (chown(TempFilename, ROOT_UID, sb.st_gid) < OK) { 613 perror("chown"); 614 fclose(tmp); 615 error = -2; 616 goto done; 617 } 618 #endif 619 620 #ifdef HAS_FCHMOD 621 if (fchmod(fileno(tmp), 0600) < OK) { 622 perror("fchmod"); 623 fclose(tmp); 624 error = -2; 625 goto done; 626 } 627 #else 628 if (chmod(TempFilename, 0600) < OK) { 629 perror("chmod"); 630 fclose(tmp); 631 error = -2; 632 goto done; 633 } 634 #endif 635 636 if (fclose(tmp) == EOF) { 637 perror("fclose"); 638 error = -2; 639 goto done; 640 } 641 642 if (!glue_strings(n, sizeof n, SPOOL_DIR, User, '/')) { 643 fprintf(stderr, "path too long\n"); 644 error = -2; 645 goto done; 646 } 647 if (rename(TempFilename, n)) { 648 fprintf(stderr, "%s: error renaming %s to %s\n", 649 ProgramName, TempFilename, n); 650 perror("rename"); 651 error = -2; 652 goto done; 653 } 654 TempFilename[0] = '\0'; 655 log_it(RealUser, Pid, "REPLACE", User); 656 657 poke_daemon(); 658 659 done: 660 (void) signal(SIGHUP, SIG_DFL); 661 (void) signal(SIGINT, SIG_DFL); 662 (void) signal(SIGQUIT, SIG_DFL); 663 if (TempFilename[0]) { 664 (void) unlink(TempFilename); 665 TempFilename[0] = '\0'; 666 } 667 return (error); 668 } 669 670 static void 671 poke_daemon() { 672 if (utime(SPOOL_DIR, NULL) < OK) { 673 fprintf(stderr, "crontab: can't update mtime on spooldir\n"); 674 perror(SPOOL_DIR); 675 return; 676 } 677 } 678 679 static void 680 clean_turds(signo) 681 int signo; 682 { 683 if (TempFilename[0]) 684 (void) unlink(TempFilename); 685 if (signo) { 686 (void) signal(signo, SIG_DFL); 687 (void) raise(signo); 688 } 689 } 690