xref: /dragonfly/usr.sbin/cron/crontab/crontab.c (revision 65c9c37a)
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  */
20 
21 /* crontab - install and manage per-user crontab files
22  * vix 02may87 [RCS has the rest of the log]
23  * vix 26jan87 [original]
24  */
25 
26 #define	MAIN_PROGRAM
27 
28 #include "cron.h"
29 #include <errno.h>
30 #include <fcntl.h>
31 #include <paths.h>
32 #include <sys/file.h>
33 #include <sys/stat.h>
34 #ifdef USE_UTIMES
35 # include <sys/time.h>
36 #else
37 # include <time.h>
38 # include <utime.h>
39 #endif
40 #if defined(POSIX)
41 # include <locale.h>
42 #endif
43 
44 
45 #define NHEADER_LINES 2
46 
47 
48 enum opt_t	{ opt_unknown, opt_list, opt_delete, opt_edit, opt_replace };
49 
50 #if DEBUGGING
51 static char	*Options[] = { "???", "list", "delete", "edit", "replace" };
52 #endif
53 
54 
55 static	PID_T		Pid;
56 static	char		User[MAX_UNAME], RealUser[MAX_UNAME];
57 static	char		Filename[MAX_FNAME];
58 static	FILE		*NewCrontab;
59 static	int		CheckErrorCount;
60 static	enum opt_t	Option;
61 static	struct passwd	*pw;
62 static	void		list_cmd(void),
63 			delete_cmd(void),
64 			edit_cmd(void),
65 			poke_daemon(void),
66 			check_error(const char *),
67 			parse_args(int c, char *v[]);
68 static	int		replace_cmd(void);
69 
70 
71 static void
usage(char * msg)72 usage(char *msg)
73 {
74 	fprintf(stderr, "crontab: usage error: %s\n", msg);
75 	fprintf(stderr, "%s\n%s\n",
76 		"usage: crontab [-u user] file",
77 		"       crontab [-u user] { -e | -l | -r }");
78 	exit(ERROR_EXIT);
79 }
80 
81 
82 int
main(int argc,char ** argv)83 main(int argc, char **argv)
84 {
85 	int	exitstatus;
86 
87 	Pid = getpid();
88 	ProgramName = argv[0];
89 
90 #if defined(POSIX)
91 	setlocale(LC_ALL, "");
92 #endif
93 
94 #if defined(BSD)
95 	setlinebuf(stderr);
96 #endif
97 	parse_args(argc, argv);		/* sets many globals, opens a file */
98 	set_cron_uid();
99 	set_cron_cwd();
100 	if (!allowed(User)) {
101 		warnx("you (%s) are not allowed to use this program", User);
102 		log_it(RealUser, Pid, "AUTH", "crontab command not allowed");
103 		exit(ERROR_EXIT);
104 	}
105 	exitstatus = OK_EXIT;
106 	switch (Option) {
107 	case opt_list:		list_cmd();
108 				break;
109 	case opt_delete:	delete_cmd();
110 				break;
111 	case opt_edit:		edit_cmd();
112 				break;
113 	case opt_replace:	if (replace_cmd() < 0)
114 					exitstatus = ERROR_EXIT;
115 				break;
116 	case opt_unknown:
117 				break;
118 	}
119 	exit(0);
120 	/*NOTREACHED*/
121 }
122 
123 
124 static void
parse_args(int argc,char ** argv)125 parse_args(int argc, char **argv)
126 {
127 	int		argch;
128 
129 	if (!(pw = getpwuid(getuid())))
130 		errx(ERROR_EXIT, "your UID isn't in the passwd file, bailing out");
131 	strncpy(User, pw->pw_name, (sizeof User)-1);
132 	User[(sizeof User)-1] = '\0';
133 	strcpy(RealUser, User);
134 	Filename[0] = '\0';
135 	Option = opt_unknown;
136 	while ((argch = getopt(argc, argv, "u:lerx:")) != -1) {
137 		switch (argch) {
138 		case 'x':
139 			if (!set_debug_flags(optarg))
140 				usage("bad debug option");
141 			break;
142 		case 'u':
143 			if (getuid() != ROOT_UID)
144 				errx(ERROR_EXIT, "must be privileged to use -u");
145 			if (!(pw = getpwnam(optarg)))
146 				errx(ERROR_EXIT, "user `%s' unknown", optarg);
147 			strncpy(User, pw->pw_name, (sizeof User)-1);
148 			User[(sizeof User)-1] = '\0';
149 			break;
150 		case 'l':
151 			if (Option != opt_unknown)
152 				usage("only one operation permitted");
153 			Option = opt_list;
154 			break;
155 		case 'r':
156 			if (Option != opt_unknown)
157 				usage("only one operation permitted");
158 			Option = opt_delete;
159 			break;
160 		case 'e':
161 			if (Option != opt_unknown)
162 				usage("only one operation permitted");
163 			Option = opt_edit;
164 			break;
165 		default:
166 			usage("unrecognized option");
167 		}
168 	}
169 
170 	endpwent();
171 
172 	if (Option != opt_unknown) {
173 		if (argv[optind] != NULL) {
174 			usage("no arguments permitted after this option");
175 		}
176 	} else {
177 		if (argv[optind] != NULL) {
178 			Option = opt_replace;
179 			strncpy (Filename, argv[optind], (sizeof Filename)-1);
180 			Filename[(sizeof Filename)-1] = '\0';
181 
182 		} else {
183 			usage("file name must be specified for replace");
184 		}
185 	}
186 
187 	if (Option == opt_replace) {
188 		/* we have to open the file here because we're going to
189 		 * chdir(2) into /var/cron before we get around to
190 		 * reading the file.
191 		 */
192 		if (!strcmp(Filename, "-")) {
193 			NewCrontab = stdin;
194 		} else {
195 			/* relinquish the setuid status of the binary during
196 			 * the open, lest nonroot users read files they should
197 			 * not be able to read.  we can't use access() here
198 			 * since there's a race condition.  thanks go out to
199 			 * Arnt Gulbrandsen <agulbra@pvv.unit.no> for spotting
200 			 * the race.
201 			 */
202 
203 			if (swap_uids() < OK)
204 				err(ERROR_EXIT, "swapping uids");
205 			if (!(NewCrontab = fopen(Filename, "r")))
206 				err(ERROR_EXIT, "%s", Filename);
207 			if (swap_uids() < OK)
208 				err(ERROR_EXIT, "swapping uids back");
209 		}
210 	}
211 
212 	Debug(DMISC, ("user=%s, file=%s, option=%s\n",
213 		      User, Filename, Options[(int)Option]))
214 }
215 
216 
217 static void
list_cmd(void)218 list_cmd(void)
219 {
220 	char	n[MAX_FNAME];
221 	FILE	*f;
222 	int	ch, x;
223 
224 	log_it(RealUser, Pid, "LIST", User);
225 	sprintf(n, CRON_TAB(User));
226 	if (!(f = fopen(n, "r"))) {
227 		if (errno == ENOENT)
228 			errx(ERROR_EXIT, "no crontab for %s", User);
229 		else
230 			err(ERROR_EXIT, "%s", n);
231 	}
232 
233 	/* file is open. copy to stdout, close.
234 	 */
235 	Set_LineNum(1)
236 
237 	/* ignore the top few comments since we probably put them there.
238 	 */
239 	for (x = 0;  x < NHEADER_LINES;  x++) {
240 		ch = get_char(f);
241 		if (EOF == ch)
242 			break;
243 		if ('#' != ch) {
244 			putchar(ch);
245 			break;
246 		}
247 		while (EOF != (ch = get_char(f)))
248 			if (ch == '\n')
249 				break;
250 		if (EOF == ch)
251 			break;
252 	}
253 
254 	while (EOF != (ch = get_char(f)))
255 		putchar(ch);
256 	fclose(f);
257 }
258 
259 
260 static void
delete_cmd(void)261 delete_cmd(void)
262 {
263 	char	n[MAX_FNAME];
264 	int ch, first;
265 
266 	if (isatty(STDIN_FILENO)) {
267 		fprintf(stderr, "remove crontab for %s? ", User);
268 		first = ch = getchar();
269 		while (ch != '\n' && ch != EOF)
270 			ch = getchar();
271 		if (first != 'y' && first != 'Y')
272 			return;
273 	}
274 
275 	log_it(RealUser, Pid, "DELETE", User);
276 	sprintf(n, CRON_TAB(User));
277 	if (unlink(n)) {
278 		if (errno == ENOENT)
279 			errx(ERROR_EXIT, "no crontab for %s", User);
280 		else
281 			err(ERROR_EXIT, "%s", n);
282 	}
283 	poke_daemon();
284 }
285 
286 
287 static void
check_error(const char * msg)288 check_error(const char *msg)
289 {
290 	CheckErrorCount++;
291 	fprintf(stderr, "\"%s\":%d: %s\n", Filename, LineNumber-1, msg);
292 }
293 
294 
295 static void
edit_cmd(void)296 edit_cmd(void)
297 {
298 	char		n[MAX_FNAME], q[MAX_TEMPSTR], *editor;
299 	FILE		*f;
300 	int		ch, t, x;
301 	struct stat	statbuf, fsbuf;
302 	time_t		mtime;
303 	WAIT_T		waiter;
304 	PID_T		pid, xpid;
305 	mode_t		um;
306 
307 	log_it(RealUser, Pid, "BEGIN EDIT", User);
308 	sprintf(n, CRON_TAB(User));
309 	if (!(f = fopen(n, "r"))) {
310 		if (errno != ENOENT)
311 			err(ERROR_EXIT, "%s", n);
312 		warnx("no crontab for %s - using an empty one", User);
313 		if (!(f = fopen(_PATH_DEVNULL, "r")))
314 			err(ERROR_EXIT, _PATH_DEVNULL);
315 	}
316 
317 	um = umask(077);
318 	sprintf(Filename, "/tmp/crontab.XXXXXXXXXX");
319 	if ((t = mkstemp(Filename)) == -1) {
320 		warn("%s", Filename);
321 		umask(um);
322 		goto fatal;
323 	}
324 	umask(um);
325 #ifdef HAS_FCHOWN
326 	if (fchown(t, getuid(), getgid()) < 0) {
327 #else
328 	if (chown(Filename, getuid(), getgid()) < 0) {
329 #endif
330 		warn("fchown");
331 		goto fatal;
332 	}
333 	if (!(NewCrontab = fdopen(t, "r+"))) {
334 		warn("fdopen");
335 		goto fatal;
336 	}
337 
338 	Set_LineNum(1)
339 
340 	/* ignore the top few comments since we probably put them there.
341 	 */
342 	for (x = 0;  x < NHEADER_LINES;  x++) {
343 		ch = get_char(f);
344 		if (EOF == ch)
345 			break;
346 		if ('#' != ch) {
347 			putc(ch, NewCrontab);
348 			break;
349 		}
350 		while (EOF != (ch = get_char(f)))
351 			if (ch == '\n')
352 				break;
353 		if (EOF == ch)
354 			break;
355 	}
356 
357 	/* copy the rest of the crontab (if any) to the temp file.
358 	 */
359 	if (EOF != ch)
360 		while (EOF != (ch = get_char(f)))
361 			putc(ch, NewCrontab);
362 	fclose(f);
363 	if (fflush(NewCrontab))
364 		err(ERROR_EXIT, "%s", Filename);
365 	if (fstat(t, &fsbuf) < 0) {
366 		warn("unable to fstat temp file");
367 		goto fatal;
368 	}
369  again:
370 	if (stat(Filename, &statbuf) < 0) {
371 		warn("stat");
372  fatal:		unlink(Filename);
373 		exit(ERROR_EXIT);
374 	}
375 	if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino)
376 		errx(ERROR_EXIT, "temp file must be edited in place");
377 	mtime = statbuf.st_mtime;
378 
379 	if ((!(editor = getenv("VISUAL")))
380 	 && (!(editor = getenv("EDITOR")))
381 	    ) {
382 		editor = EDITOR;
383 	}
384 
385 	/* we still have the file open.  editors will generally rewrite the
386 	 * original file rather than renaming/unlinking it and starting a
387 	 * new one; even backup files are supposed to be made by copying
388 	 * rather than by renaming.  if some editor does not support this,
389 	 * then don't use it.  the security problems are more severe if we
390 	 * close and reopen the file around the edit.
391 	 */
392 
393 	switch (pid = fork()) {
394 	case -1:
395 		warn("fork");
396 		goto fatal;
397 	case 0:
398 		/* child */
399 		if (setuid(getuid()) < 0)
400 			err(ERROR_EXIT, "setuid(getuid())");
401 		if (chdir("/tmp") < 0)
402 			err(ERROR_EXIT, "chdir(/tmp)");
403 		if (strlen(editor) + strlen(Filename) + 2 >= MAX_TEMPSTR)
404 			errx(ERROR_EXIT, "editor or filename too long");
405 		execlp(editor, editor, Filename, NULL);
406 		err(ERROR_EXIT, "%s", editor);
407 		/*NOTREACHED*/
408 	default:
409 		/* parent */
410 		break;
411 	}
412 
413 	/* parent */
414 	{
415 	void (*f[4])();
416 	f[0] = signal(SIGHUP, SIG_IGN);
417 	f[1] = signal(SIGINT, SIG_IGN);
418 	f[2] = signal(SIGTERM, SIG_IGN);
419 	xpid = wait(&waiter);
420 	signal(SIGHUP, f[0]);
421 	signal(SIGINT, f[1]);
422 	signal(SIGTERM, f[2]);
423 	}
424 	if (xpid != pid) {
425 		warnx("wrong PID (%d != %d) from \"%s\"", xpid, pid, editor);
426 		goto fatal;
427 	}
428 	if (WIFEXITED(waiter) && WEXITSTATUS(waiter)) {
429 		warnx("\"%s\" exited with status %d", editor, WEXITSTATUS(waiter));
430 		goto fatal;
431 	}
432 	if (WIFSIGNALED(waiter)) {
433 		warnx("\"%s\" killed; signal %d (%score dumped)",
434 			editor, WTERMSIG(waiter), WCOREDUMP(waiter) ?"" :"no ");
435 		goto fatal;
436 	}
437 	if (stat(Filename, &statbuf) < 0) {
438 		warn("stat");
439 		goto fatal;
440 	}
441 	if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino)
442 		errx(ERROR_EXIT, "temp file must be edited in place");
443 	if (mtime == statbuf.st_mtime) {
444 		warnx("no changes made to crontab");
445 		goto remove;
446 	}
447 	warnx("installing new crontab");
448 	switch (replace_cmd()) {
449 	case 0:
450 		break;
451 	case -1:
452 		for (;;) {
453 			printf("Do you want to retry the same edit? ");
454 			fflush(stdout);
455 			q[0] = '\0';
456 			fgets(q, sizeof q, stdin);
457 			switch (islower(q[0]) ? q[0] : tolower(q[0])) {
458 			case 'y':
459 				goto again;
460 			case 'n':
461 				goto abandon;
462 			default:
463 				fprintf(stderr, "Enter Y or N\n");
464 			}
465 		}
466 		/*NOTREACHED*/
467 	case -2:
468 	abandon:
469 		warnx("edits left in %s", Filename);
470 		goto done;
471 	default:
472 		warnx("panic: bad switch() in replace_cmd()");
473 		goto fatal;
474 	}
475  remove:
476 	unlink(Filename);
477  done:
478 	log_it(RealUser, Pid, "END EDIT", User);
479 }
480 
481 
482 /* returns	0	on success
483  *		-1	on syntax error
484  *		-2	on install error
485  */
486 static int
487 replace_cmd(void)
488 {
489 	char	n[MAX_FNAME - 5], envstr[MAX_ENVSTR], tn[MAX_FNAME];
490 	FILE	*tmp;
491 	int	ch, eof;
492 	entry	*e;
493 	time_t	now = time(NULL);
494 	char	**envp = env_init();
495 
496 	if (envp == NULL) {
497 		warnx("cannot allocate memory");
498 		return (-2);
499 	}
500 
501 	sprintf(n, "tmp.%d", Pid);
502 	sprintf(tn, CRON_TAB(n));
503 	if (!(tmp = fopen(tn, "w+"))) {
504 		warn("%s", tn);
505 		return (-2);
506 	}
507 
508 	/* write a signature at the top of the file.
509 	 *
510 	 * VERY IMPORTANT: make sure NHEADER_LINES agrees with this code.
511 	 */
512 	fprintf(tmp, "# DO NOT EDIT THIS FILE - edit the master and reinstall.\n");
513 	fprintf(tmp, "# (%s installed on %-24.24s)\n", Filename, ctime(&now));
514 
515 	/* copy the crontab to the tmp
516 	 */
517 	rewind(NewCrontab);
518 	Set_LineNum(1)
519 	while (EOF != (ch = get_char(NewCrontab)))
520 		putc(ch, tmp);
521 	ftruncate(fileno(tmp), ftell(tmp));
522 	fflush(tmp);  rewind(tmp);
523 
524 	if (ferror(tmp)) {
525 		warnx("error while writing new crontab to %s", tn);
526 		fclose(tmp);  unlink(tn);
527 		return (-2);
528 	}
529 
530 	/* check the syntax of the file being installed.
531 	 */
532 
533 	/* BUG: was reporting errors after the EOF if there were any errors
534 	 * in the file proper -- kludged it by stopping after first error.
535 	 *		vix 31mar87
536 	 */
537 	Set_LineNum(1 - NHEADER_LINES)
538 	CheckErrorCount = 0;  eof = FALSE;
539 	while (!CheckErrorCount && !eof) {
540 		switch (load_env(envstr, tmp)) {
541 		case ERR:
542 			eof = TRUE;
543 			break;
544 		case FALSE:
545 			e = load_entry(tmp, check_error, pw, envp);
546 			if (e)
547 				free(e);
548 			break;
549 		case TRUE:
550 			break;
551 		}
552 	}
553 
554 	if (CheckErrorCount != 0) {
555 		warnx("errors in crontab file, can't install");
556 		fclose(tmp);  unlink(tn);
557 		return (-1);
558 	}
559 
560 #ifdef HAS_FCHOWN
561 	if (fchown(fileno(tmp), ROOT_UID, -1) < OK)
562 #else
563 	if (chown(tn, ROOT_UID, -1) < OK)
564 #endif
565 	{
566 		warn("chown");
567 		fclose(tmp);  unlink(tn);
568 		return (-2);
569 	}
570 
571 #ifdef HAS_FCHMOD
572 	if (fchmod(fileno(tmp), 0600) < OK)
573 #else
574 	if (chmod(tn, 0600) < OK)
575 #endif
576 	{
577 		warn("chown");
578 		fclose(tmp);  unlink(tn);
579 		return (-2);
580 	}
581 
582 	if (fclose(tmp) == EOF) {
583 		warn("fclose");
584 		unlink(tn);
585 		return (-2);
586 	}
587 
588 	sprintf(n, CRON_TAB(User));
589 	if (rename(tn, n)) {
590 		warn("error renaming %s to %s", tn, n);
591 		unlink(tn);
592 		return (-2);
593 	}
594 	log_it(RealUser, Pid, "REPLACE", User);
595 
596 	poke_daemon();
597 
598 	return (0);
599 }
600 
601 
602 static void
603 poke_daemon(void)
604 {
605 #ifdef USE_UTIMES
606 	struct timeval tvs[2];
607 	struct timezone tz;
608 
609 	gettimeofday(&tvs[0], &tz);
610 	tvs[1] = tvs[0];
611 	if (utimes(SPOOL_DIR, tvs) < OK) {
612 		warn("can't update mtime on spooldir %s", SPOOL_DIR);
613 		return;
614 	}
615 #else
616 	if (utime(SPOOL_DIR, NULL) < OK) {
617 		warn("can't update mtime on spooldir %s", SPOOL_DIR);
618 		return;
619 	}
620 #endif /*USE_UTIMES*/
621 }
622