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 <[email protected]> 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
usage(char * msg)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
main(int argc,char * argv[])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
parse_args(argc,argv)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 <[email protected]> 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
copy_file(FILE * in,FILE * out)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
list_cmd()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
delete_cmd()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
check_error(msg)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
edit_cmd()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