xref: /dragonfly/usr.sbin/cron/crontab/crontab.c (revision 36a3d1d6) 
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  *
17  * From Id: crontab.c,v 2.13 1994/01/17 03:20:37 vixie Exp
18  * $FreeBSD: src/usr.sbin/cron/crontab/crontab.c,v 1.12.2.4 2001/06/16 03:18:37 peter Exp $
19  * $DragonFly: src/usr.sbin/cron/crontab/crontab.c,v 1.5 2004/12/18 22:48:03 swildner Exp $
20  */
21 
22 /* crontab - install and manage per-user crontab files
23  * vix 02may87 [RCS has the rest of the log]
24  * vix 26jan87 [original]
25  */
26 
27 #define	MAIN_PROGRAM
28 
29 #include "cron.h"
30 #include <errno.h>
31 #include <fcntl.h>
32 #include <paths.h>
33 #include <sys/file.h>
34 #include <sys/stat.h>
35 #ifdef USE_UTIMES
36 # include <sys/time.h>
37 #else
38 # include <time.h>
39 # include <utime.h>
40 #endif
41 #if defined(POSIX)
42 # include <locale.h>
43 #endif
44 
45 
46 #define NHEADER_LINES 3
47 
48 
49 enum opt_t	{ opt_unknown, opt_list, opt_delete, opt_edit, opt_replace };
50 
51 #if DEBUGGING
52 static char	*Options[] = { "???", "list", "delete", "edit", "replace" };
53 #endif
54 
55 
56 static	PID_T		Pid;
57 static	char		User[MAX_UNAME], RealUser[MAX_UNAME];
58 static	char		Filename[MAX_FNAME];
59 static	FILE		*NewCrontab;
60 static	int		CheckErrorCount;
61 static	enum opt_t	Option;
62 static	struct passwd	*pw;
63 static	void		list_cmd(void),
64 			delete_cmd(void),
65 			edit_cmd(void),
66 			poke_daemon(void),
67 			check_error(char *),
68 			parse_args(int c, char *v[]);
69 static	int		replace_cmd(void);
70 
71 
72 static void
73 usage(char *msg)
74 {
75 	fprintf(stderr, "crontab: usage error: %s\n", msg);
76 	fprintf(stderr, "%s\n%s\n",
77 		"usage: crontab [-u user] file",
78 		"       crontab [-u user] { -e | -l | -r }");
79 	exit(ERROR_EXIT);
80 }
81 
82 
83 int
84 main(int argc, char **argv)
85 {
86 	int	exitstatus;
87 
88 	Pid = getpid();
89 	ProgramName = argv[0];
90 
91 #if defined(POSIX)
92 	setlocale(LC_ALL, "");
93 #endif
94 
95 #if defined(BSD)
96 	setlinebuf(stderr);
97 #endif
98 	parse_args(argc, argv);		/* sets many globals, opens a file */
99 	set_cron_uid();
100 	set_cron_cwd();
101 	if (!allowed(User)) {
102 		warnx("you (%s) are not allowed to use this program", User);
103 		log_it(RealUser, Pid, "AUTH", "crontab command not allowed");
104 		exit(ERROR_EXIT);
105 	}
106 	exitstatus = OK_EXIT;
107 	switch (Option) {
108 	case opt_list:		list_cmd();
109 				break;
110 	case opt_delete:	delete_cmd();
111 				break;
112 	case opt_edit:		edit_cmd();
113 				break;
114 	case opt_replace:	if (replace_cmd() < 0)
115 					exitstatus = ERROR_EXIT;
116 				break;
117 	case opt_unknown:
118 				break;
119 	}
120 	exit(0);
121 	/*NOTREACHED*/
122 }
123 
124 
125 static void
126 parse_args(int argc, char **argv)
127 {
128 	int		argch;
129 
130 	if (!(pw = getpwuid(getuid())))
131 		errx(ERROR_EXIT, "your UID isn't in the passwd file, bailing out");
132 	strncpy(User, pw->pw_name, (sizeof User)-1);
133 	User[(sizeof User)-1] = '\0';
134 	strcpy(RealUser, User);
135 	Filename[0] = '\0';
136 	Option = opt_unknown;
137 	while ((argch = getopt(argc, argv, "u:lerx:")) != -1) {
138 		switch (argch) {
139 		case 'x':
140 			if (!set_debug_flags(optarg))
141 				usage("bad debug option");
142 			break;
143 		case 'u':
144 			if (getuid() != ROOT_UID)
145 				errx(ERROR_EXIT, "must be privileged to use -u");
146 			if (!(pw = getpwnam(optarg)))
147 				errx(ERROR_EXIT, "user `%s' unknown", optarg);
148 			strncpy(User, pw->pw_name, (sizeof User)-1);
149 			User[(sizeof User)-1] = '\0';
150 			break;
151 		case 'l':
152 			if (Option != opt_unknown)
153 				usage("only one operation permitted");
154 			Option = opt_list;
155 			break;
156 		case 'r':
157 			if (Option != opt_unknown)
158 				usage("only one operation permitted");
159 			Option = opt_delete;
160 			break;
161 		case 'e':
162 			if (Option != opt_unknown)
163 				usage("only one operation permitted");
164 			Option = opt_edit;
165 			break;
166 		default:
167 			usage("unrecognized option");
168 		}
169 	}
170 
171 	endpwent();
172 
173 	if (Option != opt_unknown) {
174 		if (argv[optind] != NULL) {
175 			usage("no arguments permitted after this option");
176 		}
177 	} else {
178 		if (argv[optind] != NULL) {
179 			Option = opt_replace;
180 			strncpy (Filename, argv[optind], (sizeof Filename)-1);
181 			Filename[(sizeof Filename)-1] = '\0';
182 
183 		} else {
184 			usage("file name must be specified for replace");
185 		}
186 	}
187 
188 	if (Option == opt_replace) {
189 		/* we have to open the file here because we're going to
190 		 * chdir(2) into /var/cron before we get around to
191 		 * reading the file.
192 		 */
193 		if (!strcmp(Filename, "-")) {
194 			NewCrontab = stdin;
195 		} else {
196 			/* relinquish the setuid status of the binary during
197 			 * the open, lest nonroot users read files they should
198 			 * not be able to read.  we can't use access() here
199 			 * since there's a race condition.  thanks go out to
200 			 * Arnt Gulbrandsen <agulbra@pvv.unit.no> for spotting
201 			 * the race.
202 			 */
203 
204 			if (swap_uids() < OK)
205 				err(ERROR_EXIT, "swapping uids");
206 			if (!(NewCrontab = fopen(Filename, "r")))
207 				err(ERROR_EXIT, "%s", Filename);
208 			if (swap_uids() < OK)
209 				err(ERROR_EXIT, "swapping uids back");
210 		}
211 	}
212 
213 	Debug(DMISC, ("user=%s, file=%s, option=%s\n",
214 		      User, Filename, Options[(int)Option]))
215 }
216 
217 
218 static void
219 list_cmd(void)
220 {
221 	char	n[MAX_FNAME];
222 	FILE	*f;
223 	int	ch, x;
224 
225 	log_it(RealUser, Pid, "LIST", User);
226 	sprintf(n, CRON_TAB(User));
227 	if (!(f = fopen(n, "r"))) {
228 		if (errno == ENOENT)
229 			errx(ERROR_EXIT, "no crontab for %s", User);
230 		else
231 			err(ERROR_EXIT, "%s", n);
232 	}
233 
234 	/* file is open. copy to stdout, close.
235 	 */
236 	Set_LineNum(1)
237 
238 	/* ignore the top few comments since we probably put them there.
239 	 */
240 	for (x = 0;  x < NHEADER_LINES;  x++) {
241 		ch = get_char(f);
242 		if (EOF == ch)
243 			break;
244 		if ('#' != ch) {
245 			putchar(ch);
246 			break;
247 		}
248 		while (EOF != (ch = get_char(f)))
249 			if (ch == '\n')
250 				break;
251 		if (EOF == ch)
252 			break;
253 	}
254 
255 	while (EOF != (ch = get_char(f)))
256 		putchar(ch);
257 	fclose(f);
258 }
259 
260 
261 static void
262 delete_cmd(void)
263 {
264 	char	n[MAX_FNAME];
265 	int ch, first;
266 
267 	if (isatty(STDIN_FILENO)) {
268 		fprintf(stderr, "remove crontab for %s? ", User);
269 		first = ch = getchar();
270 		while (ch != '\n' && ch != EOF)
271 			ch = getchar();
272 		if (first != 'y' && first != 'Y')
273 			return;
274 	}
275 
276 	log_it(RealUser, Pid, "DELETE", User);
277 	sprintf(n, CRON_TAB(User));
278 	if (unlink(n)) {
279 		if (errno == ENOENT)
280 			errx(ERROR_EXIT, "no crontab for %s", User);
281 		else
282 			err(ERROR_EXIT, "%s", n);
283 	}
284 	poke_daemon();
285 }
286 
287 
288 static void
289 check_error(char *msg)
290 {
291 	CheckErrorCount++;
292 	fprintf(stderr, "\"%s\":%d: %s\n", Filename, LineNumber-1, msg);
293 }
294 
295 
296 static void
297 edit_cmd(void)
298 {
299 	char		n[MAX_FNAME], q[MAX_TEMPSTR], *editor;
300 	FILE		*f;
301 	int		ch, t, x;
302 	struct stat	statbuf, fsbuf;
303 	time_t		mtime;
304 	WAIT_T		waiter;
305 	PID_T		pid, xpid;
306 	mode_t		um;
307 
308 	log_it(RealUser, Pid, "BEGIN EDIT", User);
309 	sprintf(n, CRON_TAB(User));
310 	if (!(f = fopen(n, "r"))) {
311 		if (errno != ENOENT)
312 			err(ERROR_EXIT, "%s", n);
313 		warnx("no crontab for %s - using an empty one", User);
314 		if (!(f = fopen(_PATH_DEVNULL, "r")))
315 			err(ERROR_EXIT, _PATH_DEVNULL);
316 	}
317 
318 	um = umask(077);
319 	sprintf(Filename, "/tmp/crontab.XXXXXXXXXX");
320 	if ((t = mkstemp(Filename)) == -1) {
321 		warn("%s", Filename);
322 		umask(um);
323 		goto fatal;
324 	}
325 	umask(um);
326 #ifdef HAS_FCHOWN
327 	if (fchown(t, getuid(), getgid()) < 0) {
328 #else
329 	if (chown(Filename, getuid(), getgid()) < 0) {
330 #endif
331 		warn("fchown");
332 		goto fatal;
333 	}
334 	if (!(NewCrontab = fdopen(t, "r+"))) {
335 		warn("fdopen");
336 		goto fatal;
337 	}
338 
339 	Set_LineNum(1)
340 
341 	/* ignore the top few comments since we probably put them there.
342 	 */
343 	for (x = 0;  x < NHEADER_LINES;  x++) {
344 		ch = get_char(f);
345 		if (EOF == ch)
346 			break;
347 		if ('#' != ch) {
348 			putc(ch, NewCrontab);
349 			break;
350 		}
351 		while (EOF != (ch = get_char(f)))
352 			if (ch == '\n')
353 				break;
354 		if (EOF == ch)
355 			break;
356 	}
357 
358 	/* copy the rest of the crontab (if any) to the temp file.
359 	 */
360 	if (EOF != ch)
361 		while (EOF != (ch = get_char(f)))
362 			putc(ch, NewCrontab);
363 	fclose(f);
364 	if (fflush(NewCrontab))
365 		err(ERROR_EXIT, "%s", Filename);
366 	if (fstat(t, &fsbuf) < 0) {
367 		warn("unable to fstat temp file");
368 		goto fatal;
369 	}
370  again:
371 	if (stat(Filename, &statbuf) < 0) {
372 		warn("stat");
373  fatal:		unlink(Filename);
374 		exit(ERROR_EXIT);
375 	}
376 	if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino)
377 		errx(ERROR_EXIT, "temp file must be edited in place");
378 	mtime = statbuf.st_mtime;
379 
380 	if ((!(editor = getenv("VISUAL")))
381 	 && (!(editor = getenv("EDITOR")))
382 	    ) {
383 		editor = EDITOR;
384 	}
385 
386 	/* we still have the file open.  editors will generally rewrite the
387 	 * original file rather than renaming/unlinking it and starting a
388 	 * new one; even backup files are supposed to be made by copying
389 	 * rather than by renaming.  if some editor does not support this,
390 	 * then don't use it.  the security problems are more severe if we
391 	 * close and reopen the file around the edit.
392 	 */
393 
394 	switch (pid = fork()) {
395 	case -1:
396 		warn("fork");
397 		goto fatal;
398 	case 0:
399 		/* child */
400 		if (setuid(getuid()) < 0)
401 			err(ERROR_EXIT, "setuid(getuid())");
402 		if (chdir("/tmp") < 0)
403 			err(ERROR_EXIT, "chdir(/tmp)");
404 		if (strlen(editor) + strlen(Filename) + 2 >= MAX_TEMPSTR)
405 			errx(ERROR_EXIT, "editor or filename too long");
406 		execlp(editor, editor, Filename, NULL);
407 		err(ERROR_EXIT, "%s", editor);
408 		/*NOTREACHED*/
409 	default:
410 		/* parent */
411 		break;
412 	}
413 
414 	/* parent */
415 	{
416 	void (*f[4])();
417 	f[0] = signal(SIGHUP, SIG_IGN);
418 	f[1] = signal(SIGINT, SIG_IGN);
419 	f[2] = signal(SIGTERM, SIG_IGN);
420 	xpid = wait(&waiter);
421 	signal(SIGHUP, f[0]);
422 	signal(SIGINT, f[1]);
423 	signal(SIGTERM, f[2]);
424 	}
425 	if (xpid != pid) {
426 		warnx("wrong PID (%d != %d) from \"%s\"", xpid, pid, editor);
427 		goto fatal;
428 	}
429 	if (WIFEXITED(waiter) && WEXITSTATUS(waiter)) {
430 		warnx("\"%s\" exited with status %d", editor, WEXITSTATUS(waiter));
431 		goto fatal;
432 	}
433 	if (WIFSIGNALED(waiter)) {
434 		warnx("\"%s\" killed; signal %d (%score dumped)",
435 			editor, WTERMSIG(waiter), WCOREDUMP(waiter) ?"" :"no ");
436 		goto fatal;
437 	}
438 	if (stat(Filename, &statbuf) < 0) {
439 		warn("stat");
440 		goto fatal;
441 	}
442 	if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino)
443 		errx(ERROR_EXIT, "temp file must be edited in place");
444 	if (mtime == statbuf.st_mtime) {
445 		warnx("no changes made to crontab");
446 		goto remove;
447 	}
448 	warnx("installing new crontab");
449 	switch (replace_cmd()) {
450 	case 0:
451 		break;
452 	case -1:
453 		for (;;) {
454 			printf("Do you want to retry the same edit? ");
455 			fflush(stdout);
456 			q[0] = '\0';
457 			fgets(q, sizeof q, stdin);
458 			switch (islower(q[0]) ? q[0] : tolower(q[0])) {
459 			case 'y':
460 				goto again;
461 			case 'n':
462 				goto abandon;
463 			default:
464 				fprintf(stderr, "Enter Y or N\n");
465 			}
466 		}
467 		/*NOTREACHED*/
468 	case -2:
469 	abandon:
470 		warnx("edits left in %s", Filename);
471 		goto done;
472 	default:
473 		warnx("panic: bad switch() in replace_cmd()");
474 		goto fatal;
475 	}
476  remove:
477 	unlink(Filename);
478  done:
479 	log_it(RealUser, Pid, "END EDIT", User);
480 }
481 
482 
483 /* returns	0	on success
484  *		-1	on syntax error
485  *		-2	on install error
486  */
487 static int
488 replace_cmd(void)
489 {
490 	char	n[MAX_FNAME], envstr[MAX_ENVSTR], tn[MAX_FNAME];
491 	FILE	*tmp;
492 	int	ch, eof;
493 	entry	*e;
494 	time_t	now = time(NULL);
495 	char	**envp = env_init();
496 
497 	if (envp == NULL) {
498 		warnx("cannot allocate memory");
499 		return (-2);
500 	}
501 
502 	sprintf(n, "tmp.%d", Pid);
503 	sprintf(tn, CRON_TAB(n));
504 	if (!(tmp = fopen(tn, "w+"))) {
505 		warn("%s", tn);
506 		return (-2);
507 	}
508 
509 	/* write a signature at the top of the file.
510 	 *
511 	 * VERY IMPORTANT: make sure NHEADER_LINES agrees with this code.
512 	 */
513 	fprintf(tmp, "# DO NOT EDIT THIS FILE - edit the master and reinstall.\n");
514 	fprintf(tmp, "# (%s installed on %-24.24s)\n", Filename, ctime(&now));
515 
516 	/* copy the crontab to the tmp
517 	 */
518 	rewind(NewCrontab);
519 	Set_LineNum(1)
520 	while (EOF != (ch = get_char(NewCrontab)))
521 		putc(ch, tmp);
522 	ftruncate(fileno(tmp), ftell(tmp));
523 	fflush(tmp);  rewind(tmp);
524 
525 	if (ferror(tmp)) {
526 		warnx("error while writing new crontab to %s", tn);
527 		fclose(tmp);  unlink(tn);
528 		return (-2);
529 	}
530 
531 	/* check the syntax of the file being installed.
532 	 */
533 
534 	/* BUG: was reporting errors after the EOF if there were any errors
535 	 * in the file proper -- kludged it by stopping after first error.
536 	 *		vix 31mar87
537 	 */
538 	Set_LineNum(1 - NHEADER_LINES)
539 	CheckErrorCount = 0;  eof = FALSE;
540 	while (!CheckErrorCount && !eof) {
541 		switch (load_env(envstr, tmp)) {
542 		case ERR:
543 			eof = TRUE;
544 			break;
545 		case FALSE:
546 			e = load_entry(tmp, check_error, pw, envp);
547 			if (e)
548 				free(e);
549 			break;
550 		case TRUE:
551 			break;
552 		}
553 	}
554 
555 	if (CheckErrorCount != 0) {
556 		warnx("errors in crontab file, can't install");
557 		fclose(tmp);  unlink(tn);
558 		return (-1);
559 	}
560 
561 #ifdef HAS_FCHOWN
562 	if (fchown(fileno(tmp), ROOT_UID, -1) < OK)
563 #else
564 	if (chown(tn, ROOT_UID, -1) < OK)
565 #endif
566 	{
567 		warn("chown");
568 		fclose(tmp);  unlink(tn);
569 		return (-2);
570 	}
571 
572 #ifdef HAS_FCHMOD
573 	if (fchmod(fileno(tmp), 0600) < OK)
574 #else
575 	if (chmod(tn, 0600) < OK)
576 #endif
577 	{
578 		warn("chown");
579 		fclose(tmp);  unlink(tn);
580 		return (-2);
581 	}
582 
583 	if (fclose(tmp) == EOF) {
584 		warn("fclose");
585 		unlink(tn);
586 		return (-2);
587 	}
588 
589 	sprintf(n, CRON_TAB(User));
590 	if (rename(tn, n)) {
591 		warn("error renaming %s to %s", tn, n);
592 		unlink(tn);
593 		return (-2);
594 	}
595 	log_it(RealUser, Pid, "REPLACE", User);
596 
597 	poke_daemon();
598 
599 	return (0);
600 }
601 
602 
603 static void
604 poke_daemon(void)
605 {
606 #ifdef USE_UTIMES
607 	struct timeval tvs[2];
608 	struct timezone tz;
609 
610 	gettimeofday(&tvs[0], &tz);
611 	tvs[1] = tvs[0];
612 	if (utimes(SPOOL_DIR, tvs) < OK) {
613 		warn("can't update mtime on spooldir %s", SPOOL_DIR);
614 		return;
615 	}
616 #else
617 	if (utime(SPOOL_DIR, NULL) < OK) {
618 		warn("can't update mtime on spooldir %s", SPOOL_DIR);
619 		return;
620 	}
621 #endif /*USE_UTIMES*/
622 }
623