1 /* Copyright 1988,1990,1993,1994 by Paul Vixie 2 * All rights reserved 3 * 4 * Distribute freely, except: don't remove my name from the source or 5 * documentation (don't take credit for my work), mark your changes (don't 6 * get me blamed for your possible bugs), don't alter or remove this 7 * notice. May be sold if buildable source is provided to buyer. No 8 * warrantee of any kind, express or implied, is included with this 9 * software; use at your own risk, responsibility for damages (if any) to 10 * anyone resulting from the use of this software rests entirely with the 11 * user. 12 * 13 * Send bug reports, bug fixes, enhancements, requests, flames, etc., and 14 * I'll try to keep a version up to date. I can be reached as follows: 15 * Paul Vixie <paul@vix.com> uunet!decwrl!vixie!paul 16 * From Id: crontab.c,v 2.13 1994/01/17 03:20:37 vixie Exp 17 */ 18 19 #if !defined(lint) && !defined(LINT) 20 static const char rcsid[] = 21 "$FreeBSD$"; 22 #endif 23 24 /* crontab - install and manage per-user crontab files 25 * vix 02may87 [RCS has the rest of the log] 26 * vix 26jan87 [original] 27 */ 28 29 #define MAIN_PROGRAM 30 31 #include <sys/param.h> 32 #include "cron.h" 33 #include <errno.h> 34 #include <fcntl.h> 35 #include <md5.h> 36 #include <paths.h> 37 #include <sys/file.h> 38 #include <sys/stat.h> 39 #ifdef USE_UTIMES 40 # include <sys/time.h> 41 #else 42 # include <time.h> 43 # include <utime.h> 44 #endif 45 #if defined(POSIX) 46 # include <locale.h> 47 #endif 48 49 #define MD5_SIZE 33 50 #define NHEADER_LINES 3 51 52 53 enum opt_t { opt_unknown, opt_list, opt_delete, opt_edit, opt_replace }; 54 55 #if DEBUGGING 56 static char *Options[] = { "???", "list", "delete", "edit", "replace" }; 57 #endif 58 59 60 static PID_T Pid; 61 static char User[MAXLOGNAME], RealUser[MAXLOGNAME]; 62 static char Filename[MAX_FNAME]; 63 static FILE *NewCrontab; 64 static int CheckErrorCount; 65 static enum opt_t Option; 66 static int fflag; 67 static struct passwd *pw; 68 static void list_cmd(void), 69 delete_cmd(void), 70 edit_cmd(void), 71 poke_daemon(void), 72 check_error(char *), 73 parse_args(int c, char *v[]); 74 static int replace_cmd(void); 75 76 77 static void 78 usage(char *msg) 79 { 80 fprintf(stderr, "crontab: usage error: %s\n", msg); 81 fprintf(stderr, "%s\n%s\n", 82 "usage: crontab [-u user] file", 83 " crontab [-u user] { -l | -r [-f] | -e }"); 84 exit(ERROR_EXIT); 85 } 86 87 88 int 89 main(int argc, char *argv[]) 90 { 91 int exitstatus; 92 93 Pid = getpid(); 94 ProgramName = argv[0]; 95 96 #if defined(POSIX) 97 setlocale(LC_ALL, ""); 98 #endif 99 100 #if defined(BSD) 101 setlinebuf(stderr); 102 #endif 103 parse_args(argc, argv); /* sets many globals, opens a file */ 104 set_cron_uid(); 105 set_cron_cwd(); 106 if (!allowed(User)) { 107 warnx("you (%s) are not allowed to use this program", User); 108 log_it(RealUser, Pid, "AUTH", "crontab command not allowed"); 109 exit(ERROR_EXIT); 110 } 111 exitstatus = OK_EXIT; 112 switch (Option) { 113 case opt_list: list_cmd(); 114 break; 115 case opt_delete: delete_cmd(); 116 break; 117 case opt_edit: edit_cmd(); 118 break; 119 case opt_replace: if (replace_cmd() < 0) 120 exitstatus = ERROR_EXIT; 121 break; 122 case opt_unknown: 123 break; 124 } 125 exit(exitstatus); 126 /*NOTREACHED*/ 127 } 128 129 130 static void 131 parse_args(argc, argv) 132 int argc; 133 char *argv[]; 134 { 135 int argch; 136 char resolved_path[PATH_MAX]; 137 138 if (!(pw = getpwuid(getuid()))) 139 errx(ERROR_EXIT, "your UID isn't in the passwd file, bailing out"); 140 bzero(pw->pw_passwd, strlen(pw->pw_passwd)); 141 (void) strncpy(User, pw->pw_name, (sizeof User)-1); 142 User[(sizeof User)-1] = '\0'; 143 strcpy(RealUser, User); 144 Filename[0] = '\0'; 145 Option = opt_unknown; 146 while ((argch = getopt(argc, argv, "u:lerx:f")) != -1) { 147 switch (argch) { 148 case 'x': 149 if (!set_debug_flags(optarg)) 150 usage("bad debug option"); 151 break; 152 case 'u': 153 if (getuid() != ROOT_UID) 154 errx(ERROR_EXIT, "must be privileged to use -u"); 155 if (!(pw = getpwnam(optarg))) 156 errx(ERROR_EXIT, "user `%s' unknown", optarg); 157 bzero(pw->pw_passwd, strlen(pw->pw_passwd)); 158 (void) strncpy(User, pw->pw_name, (sizeof User)-1); 159 User[(sizeof User)-1] = '\0'; 160 break; 161 case 'l': 162 if (Option != opt_unknown) 163 usage("only one operation permitted"); 164 Option = opt_list; 165 break; 166 case 'r': 167 if (Option != opt_unknown) 168 usage("only one operation permitted"); 169 Option = opt_delete; 170 break; 171 case 'e': 172 if (Option != opt_unknown) 173 usage("only one operation permitted"); 174 Option = opt_edit; 175 break; 176 case 'f': 177 fflag = 1; 178 break; 179 default: 180 usage("unrecognized option"); 181 } 182 } 183 184 endpwent(); 185 186 if (Option != opt_unknown) { 187 if (argv[optind] != NULL) { 188 usage("no arguments permitted after this option"); 189 } 190 } else { 191 if (argv[optind] != NULL) { 192 Option = opt_replace; 193 (void) strncpy (Filename, argv[optind], (sizeof Filename)-1); 194 Filename[(sizeof Filename)-1] = '\0'; 195 196 } else { 197 usage("file name must be specified for replace"); 198 } 199 } 200 201 if (Option == opt_replace) { 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 err(ERROR_EXIT, "swapping uids"); 212 213 /* we have to open the file here because we're going to 214 * chdir(2) into /var/cron before we get around to 215 * reading the file. 216 */ 217 if (!strcmp(Filename, "-")) { 218 NewCrontab = stdin; 219 } else if (realpath(Filename, resolved_path) != NULL && 220 !strcmp(resolved_path, SYSCRONTAB)) { 221 err(ERROR_EXIT, SYSCRONTAB " must be edited manually"); 222 } else { 223 if (!(NewCrontab = fopen(Filename, "r"))) 224 err(ERROR_EXIT, "%s", Filename); 225 } 226 if (swap_uids_back() < OK) 227 err(ERROR_EXIT, "swapping uids back"); 228 } 229 230 Debug(DMISC, ("user=%s, file=%s, option=%s\n", 231 User, Filename, Options[(int)Option])) 232 } 233 234 static void 235 copy_file(FILE *in, FILE *out) { 236 int x, ch; 237 238 Set_LineNum(1) 239 /* ignore the top few comments since we probably put them there. 240 */ 241 for (x = 0; x < NHEADER_LINES; x++) { 242 ch = get_char(in); 243 if (EOF == ch) 244 break; 245 if ('#' != ch) { 246 putc(ch, out); 247 break; 248 } 249 while (EOF != (ch = get_char(in))) 250 if (ch == '\n') 251 break; 252 if (EOF == ch) 253 break; 254 } 255 256 /* copy the rest of the crontab (if any) to the output file. 257 */ 258 if (EOF != ch) 259 while (EOF != (ch = get_char(in))) 260 putc(ch, out); 261 } 262 263 static void 264 list_cmd() { 265 char n[MAX_FNAME]; 266 FILE *f; 267 268 log_it(RealUser, Pid, "LIST", User); 269 (void) snprintf(n, sizeof(n), CRON_TAB(User)); 270 if (!(f = fopen(n, "r"))) { 271 if (errno == ENOENT) 272 errx(ERROR_EXIT, "no crontab for %s", User); 273 else 274 err(ERROR_EXIT, "%s", n); 275 } 276 277 /* file is open. copy to stdout, close. 278 */ 279 copy_file(f, stdout); 280 fclose(f); 281 } 282 283 284 static void 285 delete_cmd() { 286 char n[MAX_FNAME]; 287 int ch, first; 288 289 if (!fflag && isatty(STDIN_FILENO)) { 290 (void)fprintf(stderr, "remove crontab for %s? ", User); 291 first = ch = getchar(); 292 while (ch != '\n' && ch != EOF) 293 ch = getchar(); 294 if (first != 'y' && first != 'Y') 295 return; 296 } 297 298 log_it(RealUser, Pid, "DELETE", User); 299 (void) snprintf(n, sizeof(n), CRON_TAB(User)); 300 if (unlink(n)) { 301 if (errno == ENOENT) 302 errx(ERROR_EXIT, "no crontab for %s", User); 303 else 304 err(ERROR_EXIT, "%s", n); 305 } 306 poke_daemon(); 307 } 308 309 310 static void 311 check_error(msg) 312 char *msg; 313 { 314 CheckErrorCount++; 315 fprintf(stderr, "\"%s\":%d: %s\n", Filename, LineNumber-1, msg); 316 } 317 318 319 static void 320 edit_cmd() { 321 char n[MAX_FNAME], q[MAX_TEMPSTR], *editor; 322 FILE *f; 323 int t; 324 struct stat statbuf, fsbuf; 325 WAIT_T waiter; 326 PID_T pid, xpid; 327 mode_t um; 328 int syntax_error = 0; 329 char orig_md5[MD5_SIZE]; 330 char new_md5[MD5_SIZE]; 331 332 log_it(RealUser, Pid, "BEGIN EDIT", User); 333 (void) snprintf(n, sizeof(n), CRON_TAB(User)); 334 if (!(f = fopen(n, "r"))) { 335 if (errno != ENOENT) 336 err(ERROR_EXIT, "%s", n); 337 warnx("no crontab for %s - using an empty one", User); 338 if (!(f = fopen(_PATH_DEVNULL, "r"))) 339 err(ERROR_EXIT, _PATH_DEVNULL); 340 } 341 342 um = umask(077); 343 (void) snprintf(Filename, sizeof(Filename), "/tmp/crontab.XXXXXXXXXX"); 344 if ((t = mkstemp(Filename)) == -1) { 345 warn("%s", Filename); 346 (void) umask(um); 347 goto fatal; 348 } 349 (void) umask(um); 350 #ifdef HAS_FCHOWN 351 if (fchown(t, getuid(), getgid()) < 0) { 352 #else 353 if (chown(Filename, getuid(), getgid()) < 0) { 354 #endif 355 warn("fchown"); 356 goto fatal; 357 } 358 if (!(NewCrontab = fdopen(t, "r+"))) { 359 warn("fdopen"); 360 goto fatal; 361 } 362 363 copy_file(f, NewCrontab); 364 fclose(f); 365 if (fflush(NewCrontab)) 366 err(ERROR_EXIT, "%s", Filename); 367 if (fstat(t, &fsbuf) < 0) { 368 warn("unable to fstat temp file"); 369 goto fatal; 370 } 371 again: 372 if (swap_uids() < OK) 373 err(ERROR_EXIT, "swapping uids"); 374 if (stat(Filename, &statbuf) < 0) { 375 warn("stat"); 376 fatal: unlink(Filename); 377 exit(ERROR_EXIT); 378 } 379 if (swap_uids_back() < OK) 380 err(ERROR_EXIT, "swapping uids back"); 381 if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino) 382 errx(ERROR_EXIT, "temp file must be edited in place"); 383 if (MD5File(Filename, orig_md5) == NULL) { 384 warn("MD5"); 385 goto fatal; 386 } 387 388 if ((!(editor = getenv("VISUAL"))) 389 && (!(editor = getenv("EDITOR"))) 390 ) { 391 editor = EDITOR; 392 } 393 394 /* we still have the file open. editors will generally rewrite the 395 * original file rather than renaming/unlinking it and starting a 396 * new one; even backup files are supposed to be made by copying 397 * rather than by renaming. if some editor does not support this, 398 * then don't use it. the security problems are more severe if we 399 * close and reopen the file around the edit. 400 */ 401 402 switch (pid = fork()) { 403 case -1: 404 warn("fork"); 405 goto fatal; 406 case 0: 407 /* child */ 408 if (setuid(getuid()) < 0) 409 err(ERROR_EXIT, "setuid(getuid())"); 410 if (chdir("/tmp") < 0) 411 err(ERROR_EXIT, "chdir(/tmp)"); 412 if (strlen(editor) + strlen(Filename) + 2 >= MAX_TEMPSTR) 413 errx(ERROR_EXIT, "editor or filename too long"); 414 execlp(editor, editor, Filename, (char *)NULL); 415 err(ERROR_EXIT, "%s", editor); 416 /*NOTREACHED*/ 417 default: 418 /* parent */ 419 break; 420 } 421 422 /* parent */ 423 { 424 void (*sig[3])(int signal); 425 sig[0] = signal(SIGHUP, SIG_IGN); 426 sig[1] = signal(SIGINT, SIG_IGN); 427 sig[2] = signal(SIGTERM, SIG_IGN); 428 xpid = wait(&waiter); 429 signal(SIGHUP, sig[0]); 430 signal(SIGINT, sig[1]); 431 signal(SIGTERM, sig[2]); 432 } 433 if (xpid != pid) { 434 warnx("wrong PID (%d != %d) from \"%s\"", xpid, pid, editor); 435 goto fatal; 436 } 437 if (WIFEXITED(waiter) && WEXITSTATUS(waiter)) { 438 warnx("\"%s\" exited with status %d", editor, WEXITSTATUS(waiter)); 439 goto fatal; 440 } 441 if (WIFSIGNALED(waiter)) { 442 warnx("\"%s\" killed; signal %d (%score dumped)", 443 editor, WTERMSIG(waiter), WCOREDUMP(waiter) ?"" :"no "); 444 goto fatal; 445 } 446 if (swap_uids() < OK) 447 err(ERROR_EXIT, "swapping uids"); 448 if (stat(Filename, &statbuf) < 0) { 449 warn("stat"); 450 goto fatal; 451 } 452 if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino) 453 errx(ERROR_EXIT, "temp file must be edited in place"); 454 if (MD5File(Filename, new_md5) == NULL) { 455 warn("MD5"); 456 goto fatal; 457 } 458 if (swap_uids_back() < OK) 459 err(ERROR_EXIT, "swapping uids back"); 460 if (strcmp(orig_md5, new_md5) == 0 && !syntax_error) { 461 warnx("no changes made to crontab"); 462 goto remove; 463 } 464 warnx("installing new crontab"); 465 switch (replace_cmd()) { 466 case 0: /* Success */ 467 break; 468 case -1: /* Syntax error */ 469 for (;;) { 470 printf("Do you want to retry the same edit? "); 471 fflush(stdout); 472 q[0] = '\0'; 473 (void) fgets(q, sizeof q, stdin); 474 switch (islower(q[0]) ? q[0] : tolower(q[0])) { 475 case 'y': 476 syntax_error = 1; 477 goto again; 478 case 'n': 479 goto abandon; 480 default: 481 fprintf(stderr, "Enter Y or N\n"); 482 } 483 } 484 /*NOTREACHED*/ 485 case -2: /* Install error */ 486 abandon: 487 warnx("edits left in %s", Filename); 488 goto done; 489 default: 490 warnx("panic: bad switch() in replace_cmd()"); 491 goto fatal; 492 } 493 remove: 494 unlink(Filename); 495 done: 496 log_it(RealUser, Pid, "END EDIT", User); 497 } 498 499 500 /* returns 0 on success 501 * -1 on syntax error 502 * -2 on install error 503 */ 504 static int 505 replace_cmd() { 506 char n[MAX_FNAME], envstr[MAX_ENVSTR], tn[MAX_FNAME]; 507 FILE *tmp; 508 int ch, eof; 509 entry *e; 510 time_t now = time(NULL); 511 char **envp = env_init(); 512 513 if (envp == NULL) { 514 warnx("cannot allocate memory"); 515 return (-2); 516 } 517 518 (void) snprintf(n, sizeof(n), "tmp.%d", Pid); 519 (void) snprintf(tn, sizeof(tn), CRON_TAB(n)); 520 521 if (!(tmp = fopen(tn, "w+"))) { 522 warn("%s", tn); 523 return (-2); 524 } 525 526 /* write a signature at the top of the file. 527 * 528 * VERY IMPORTANT: make sure NHEADER_LINES agrees with this code. 529 */ 530 fprintf(tmp, "# DO NOT EDIT THIS FILE - edit the master and reinstall.\n"); 531 fprintf(tmp, "# (%s installed on %-24.24s)\n", Filename, ctime(&now)); 532 fprintf(tmp, "# (Cron version -- %s)\n", rcsid); 533 534 /* copy the crontab to the tmp 535 */ 536 rewind(NewCrontab); 537 Set_LineNum(1) 538 while (EOF != (ch = get_char(NewCrontab))) 539 putc(ch, tmp); 540 ftruncate(fileno(tmp), ftello(tmp)); 541 fflush(tmp); rewind(tmp); 542 543 if (ferror(tmp)) { 544 warnx("error while writing new crontab to %s", tn); 545 fclose(tmp); unlink(tn); 546 return (-2); 547 } 548 549 /* check the syntax of the file being installed. 550 */ 551 552 /* BUG: was reporting errors after the EOF if there were any errors 553 * in the file proper -- kludged it by stopping after first error. 554 * vix 31mar87 555 */ 556 Set_LineNum(1 - NHEADER_LINES) 557 CheckErrorCount = 0; eof = FALSE; 558 while (!CheckErrorCount && !eof) { 559 switch (load_env(envstr, tmp)) { 560 case ERR: 561 eof = TRUE; 562 break; 563 case FALSE: 564 e = load_entry(tmp, check_error, pw, envp); 565 if (e) 566 free_entry(e); 567 break; 568 case TRUE: 569 break; 570 } 571 } 572 573 if (CheckErrorCount != 0) { 574 warnx("errors in crontab file, can't install"); 575 fclose(tmp); unlink(tn); 576 return (-1); 577 } 578 579 #ifdef HAS_FCHOWN 580 if (fchown(fileno(tmp), ROOT_UID, -1) < OK) 581 #else 582 if (chown(tn, ROOT_UID, -1) < OK) 583 #endif 584 { 585 warn("chown"); 586 fclose(tmp); unlink(tn); 587 return (-2); 588 } 589 590 #ifdef HAS_FCHMOD 591 if (fchmod(fileno(tmp), 0600) < OK) 592 #else 593 if (chmod(tn, 0600) < OK) 594 #endif 595 { 596 warn("chown"); 597 fclose(tmp); unlink(tn); 598 return (-2); 599 } 600 601 if (fclose(tmp) == EOF) { 602 warn("fclose"); 603 unlink(tn); 604 return (-2); 605 } 606 607 (void) snprintf(n, sizeof(n), CRON_TAB(User)); 608 if (rename(tn, n)) { 609 warn("error renaming %s to %s", tn, n); 610 unlink(tn); 611 return (-2); 612 } 613 614 log_it(RealUser, Pid, "REPLACE", User); 615 616 /* 617 * Creating the 'tn' temp file has already updated the 618 * modification time of the spool directory. Sleep for a 619 * second to ensure that poke_daemon() sets a later 620 * modification time. Otherwise, this can race with the cron 621 * daemon scanning for updated crontabs. 622 */ 623 sleep(1); 624 625 poke_daemon(); 626 627 return (0); 628 } 629 630 631 static void 632 poke_daemon() { 633 #ifdef USE_UTIMES 634 struct timeval tvs[2]; 635 636 (void)gettimeofday(&tvs[0], NULL); 637 tvs[1] = tvs[0]; 638 if (utimes(SPOOL_DIR, tvs) < OK) { 639 warn("can't update mtime on spooldir %s", SPOOL_DIR); 640 return; 641 } 642 #else 643 if (utime(SPOOL_DIR, NULL) < OK) { 644 warn("can't update mtime on spooldir %s", SPOOL_DIR); 645 return; 646 } 647 #endif /*USE_UTIMES*/ 648 } 649