crontab.c revision 20573 
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)
20static char rcsid[] = "$Id: crontab.c,v 1.6 1996/08/05 00:50:02 pst Exp $";
21#endif
22
23/* crontab - install and manage per-user crontab files
24 * vix 02may87 [RCS has the rest of the log]
25 * vix 26jan87 [original]
26 */
27
28#define	MAIN_PROGRAM
29
30#include "cron.h"
31#include <errno.h>
32#include <fcntl.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
49enum opt_t	{ opt_unknown, opt_list, opt_delete, opt_edit, opt_replace };
50
51#if DEBUGGING
52static char	*Options[] = { "???", "list", "delete", "edit", "replace" };
53#endif
54
55
56static	PID_T		Pid;
57static	char		User[MAX_UNAME], RealUser[MAX_UNAME];
58static	char		Filename[MAX_FNAME];
59static	FILE		*NewCrontab;
60static	int		CheckErrorCount;
61static	enum opt_t	Option;
62static	struct passwd	*pw;
63static	void		list_cmd __P((void)),
64			delete_cmd __P((void)),
65			edit_cmd __P((void)),
66			poke_daemon __P((void)),
67			check_error __P((char *)),
68			parse_args __P((int c, char *v[]));
69static	int		replace_cmd __P((void));
70
71
72static void
73usage(msg)
74	char *msg;
75{
76	fprintf(stderr, "%s: usage error: %s\n", ProgramName, msg);
77	fprintf(stderr, "usage:\t%s [-u user] file\n", ProgramName);
78	fprintf(stderr, "\t%s [-u user] { -e | -l | -r }\n", ProgramName);
79	fprintf(stderr, "\t\t(default operation is replace, per 1003.2)\n");
80	fprintf(stderr, "\t-e\t(edit user's crontab)\n");
81	fprintf(stderr, "\t-l\t(list user's crontab)\n");
82	fprintf(stderr, "\t-r\t(delete user's crontab)\n");
83	exit(ERROR_EXIT);
84}
85
86
87int
88main(argc, argv)
89	int	argc;
90	char	*argv[];
91{
92	int	exitstatus;
93
94	Pid = getpid();
95	ProgramName = argv[0];
96
97#if defined(POSIX)
98	setlocale(LC_ALL, "");
99#endif
100
101#if defined(BSD)
102	setlinebuf(stderr);
103#endif
104	parse_args(argc, argv);		/* sets many globals, opens a file */
105	set_cron_uid();
106	set_cron_cwd();
107	if (!allowed(User)) {
108		fprintf(stderr,
109			"You (%s) are not allowed to use this program (%s)\n",
110			User, ProgramName);
111		fprintf(stderr, "See crontab(1) for more information\n");
112		log_it(RealUser, Pid, "AUTH", "crontab command not allowed");
113		exit(ERROR_EXIT);
114	}
115	exitstatus = OK_EXIT;
116	switch (Option) {
117	case opt_list:		list_cmd();
118				break;
119	case opt_delete:	delete_cmd();
120				break;
121	case opt_edit:		edit_cmd();
122				break;
123	case opt_replace:	if (replace_cmd() < 0)
124					exitstatus = ERROR_EXIT;
125				break;
126	}
127	exit(0);
128	/*NOTREACHED*/
129}
130
131
132static void
133parse_args(argc, argv)
134	int	argc;
135	char	*argv[];
136{
137	int		argch;
138
139	if (!(pw = getpwuid(getuid()))) {
140		fprintf(stderr, "%s: your UID isn't in the passwd file.\n",
141			ProgramName);
142		fprintf(stderr, "bailing out.\n");
143		exit(ERROR_EXIT);
144	}
145	(void) strncpy(User, pw->pw_name, (sizeof User)-1);
146	User[(sizeof User)-1] = '\0';
147	strcpy(RealUser, User);
148	Filename[0] = '\0';
149	Option = opt_unknown;
150	while (EOF != (argch = getopt(argc, argv, "u:lerx:"))) {
151		switch (argch) {
152		case 'x':
153			if (!set_debug_flags(optarg))
154				usage("bad debug option");
155			break;
156		case 'u':
157			if (getuid() != ROOT_UID)
158			{
159				fprintf(stderr,
160					"must be privileged to use -u\n");
161				exit(ERROR_EXIT);
162			}
163			if (!(pw = getpwnam(optarg)))
164			{
165				fprintf(stderr, "%s:  user `%s' unknown\n",
166					ProgramName, optarg);
167				exit(ERROR_EXIT);
168			}
169			(void) strncpy(User, pw->pw_name, (sizeof User)-1);
170			User[(sizeof User)-1] = '\0';
171			break;
172		case 'l':
173			if (Option != opt_unknown)
174				usage("only one operation permitted");
175			Option = opt_list;
176			break;
177		case 'r':
178			if (Option != opt_unknown)
179				usage("only one operation permitted");
180			Option = opt_delete;
181			break;
182		case 'e':
183			if (Option != opt_unknown)
184				usage("only one operation permitted");
185			Option = opt_edit;
186			break;
187		default:
188			usage("unrecognized option");
189		}
190	}
191
192	endpwent();
193
194	if (Option != opt_unknown) {
195		if (argv[optind] != NULL) {
196			usage("no arguments permitted after this option");
197		}
198	} else {
199		if (argv[optind] != NULL) {
200			Option = opt_replace;
201			(void) strncpy (Filename, argv[optind], (sizeof Filename)-1);
202			Filename[(sizeof Filename)-1] = '\0';
203
204		} else {
205			usage("file name must be specified for replace");
206		}
207	}
208
209	if (Option == opt_replace) {
210		/* we have to open the file here because we're going to
211		 * chdir(2) into /var/cron before we get around to
212		 * reading the file.
213		 */
214		if (!strcmp(Filename, "-")) {
215			NewCrontab = stdin;
216		} else {
217			/* relinquish the setuid status of the binary during
218			 * the open, lest nonroot users read files they should
219			 * not be able to read.  we can't use access() here
220			 * since there's a race condition.  thanks go out to
221			 * Arnt Gulbrandsen <agulbra@pvv.unit.no> for spotting
222			 * the race.
223			 */
224
225			if (swap_uids() < OK) {
226				perror("swapping uids");
227				exit(ERROR_EXIT);
228			}
229			if (!(NewCrontab = fopen(Filename, "r"))) {
230				perror(Filename);
231				exit(ERROR_EXIT);
232			}
233			if (swap_uids() < OK) {
234				perror("swapping uids back");
235				exit(ERROR_EXIT);
236			}
237		}
238	}
239
240	Debug(DMISC, ("user=%s, file=%s, option=%s\n",
241		      User, Filename, Options[(int)Option]))
242}
243
244
245static void
246list_cmd() {
247	char	n[MAX_FNAME];
248	FILE	*f;
249	int	ch;
250
251	log_it(RealUser, Pid, "LIST", User);
252	(void) sprintf(n, CRON_TAB(User));
253	if (!(f = fopen(n, "r"))) {
254		if (errno == ENOENT)
255			fprintf(stderr, "no crontab for %s\n", User);
256		else
257			perror(n);
258		exit(ERROR_EXIT);
259	}
260
261	/* file is open. copy to stdout, close.
262	 */
263	Set_LineNum(1)
264	while (EOF != (ch = get_char(f)))
265		putchar(ch);
266	fclose(f);
267}
268
269
270static void
271delete_cmd() {
272	char	n[MAX_FNAME];
273
274	log_it(RealUser, Pid, "DELETE", User);
275	(void) sprintf(n, CRON_TAB(User));
276	if (unlink(n)) {
277		if (errno == ENOENT)
278			fprintf(stderr, "no crontab for %s\n", User);
279		else
280			perror(n);
281		exit(ERROR_EXIT);
282	}
283	poke_daemon();
284}
285
286
287static void
288check_error(msg)
289	char	*msg;
290{
291	CheckErrorCount++;
292	fprintf(stderr, "\"%s\":%d: %s\n", Filename, LineNumber-1, msg);
293}
294
295
296static void
297edit_cmd() {
298	char		n[MAX_FNAME], q[MAX_TEMPSTR], *editor;
299	FILE		*f;
300	int		ch, t, x;
301	struct stat	statbuf;
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	(void) sprintf(n, CRON_TAB(User));
309	if (!(f = fopen(n, "r"))) {
310		if (errno != ENOENT) {
311			perror(n);
312			exit(ERROR_EXIT);
313		}
314		fprintf(stderr, "no crontab for %s - using an empty one\n",
315			User);
316		if (!(f = fopen("/dev/null", "r"))) {
317			perror("/dev/null");
318			exit(ERROR_EXIT);
319		}
320	}
321
322	um = umask(077);
323	(void) sprintf(Filename, "/tmp/crontab.XXXXXXXXXX");
324	if ((t = mkstemp(Filename)) == -1) {
325		perror(Filename);
326		(void) umask(um);
327		goto fatal;
328	}
329	(void) umask(um);
330#ifdef HAS_FCHOWN
331	if (fchown(t, getuid(), getgid()) < 0) {
332#else
333	if (chown(Filename, getuid(), getgid()) < 0) {
334#endif
335		perror("fchown");
336		goto fatal;
337	}
338	if (!(NewCrontab = fdopen(t, "w"))) {
339		perror("fdopen");
340		goto fatal;
341	}
342
343	Set_LineNum(1)
344
345	/* ignore the top few comments since we probably put them there.
346	 */
347	for (x = 0;  x < NHEADER_LINES;  x++) {
348		ch = get_char(f);
349		if (EOF == ch)
350			break;
351		if ('#' != ch) {
352			putc(ch, NewCrontab);
353			break;
354		}
355		while (EOF != (ch = get_char(f)))
356			if (ch == '\n')
357				break;
358		if (EOF == ch)
359			break;
360	}
361
362	/* copy the rest of the crontab (if any) to the temp file.
363	 */
364	if (EOF != ch)
365		while (EOF != (ch = get_char(f)))
366			putc(ch, NewCrontab);
367	fclose(f);
368	if (fclose(NewCrontab)) {
369		perror(Filename);
370		exit(ERROR_EXIT);
371	}
372 again:
373	if (stat(Filename, &statbuf) < 0) {
374		perror("stat");
375 fatal:		unlink(Filename);
376		exit(ERROR_EXIT);
377	}
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		perror("fork");
397		goto fatal;
398	case 0:
399		/* child */
400		if (setuid(getuid()) < 0) {
401			perror("setuid(getuid())");
402			exit(ERROR_EXIT);
403		}
404		if (chdir("/tmp") < 0) {
405			perror("chdir(/tmp)");
406			exit(ERROR_EXIT);
407		}
408		if (strlen(editor) + strlen(Filename) + 2 >= MAX_TEMPSTR) {
409			fprintf(stderr, "%s: editor or filename too long\n",
410				ProgramName);
411			exit(ERROR_EXIT);
412		}
413		execlp(editor, editor, Filename, NULL);
414		perror(editor);
415		exit(ERROR_EXIT);
416		/*NOTREACHED*/
417	default:
418		/* parent */
419		break;
420	}
421
422	/* parent */
423	{
424	void (*f[4])();
425	f[0] = signal(SIGHUP, SIG_IGN);
426	f[1] = signal(SIGINT, SIG_IGN);
427	f[2] = signal(SIGTERM, SIG_IGN);
428	xpid = wait(&waiter);
429	signal(SIGHUP, f[0]);
430	signal(SIGINT, f[1]);
431	signal(SIGTERM, f[2]);
432	}
433	if (xpid != pid) {
434		fprintf(stderr, "%s: wrong PID (%d != %d) from \"%s\"\n",
435			ProgramName, xpid, pid, editor);
436		goto fatal;
437	}
438	if (WIFEXITED(waiter) && WEXITSTATUS(waiter)) {
439		fprintf(stderr, "%s: \"%s\" exited with status %d\n",
440			ProgramName, editor, WEXITSTATUS(waiter));
441		goto fatal;
442	}
443	if (WIFSIGNALED(waiter)) {
444		fprintf(stderr,
445			"%s: \"%s\" killed; signal %d (%score dumped)\n",
446			ProgramName, editor, WTERMSIG(waiter),
447			WCOREDUMP(waiter) ?"" :"no ");
448		goto fatal;
449	}
450	if (stat(Filename, &statbuf) < 0) {
451		perror("stat");
452		goto fatal;
453	}
454	if (mtime == statbuf.st_mtime) {
455		fprintf(stderr, "%s: no changes made to crontab\n",
456			ProgramName);
457		goto remove;
458	}
459	fprintf(stderr, "%s: installing new crontab\n", ProgramName);
460	if (!(NewCrontab = fopen(Filename, "r"))) {
461		perror(Filename);
462		goto fatal;
463	}
464	switch (replace_cmd()) {
465	case 0:
466		break;
467	case -1:
468		for (;;) {
469			printf("Do you want to retry the same edit? ");
470			fflush(stdout);
471			q[0] = '\0';
472			(void) fgets(q, sizeof q, stdin);
473			switch (islower(q[0]) ? q[0] : tolower(q[0])) {
474			case 'y':
475				goto again;
476			case 'n':
477				goto abandon;
478			default:
479				fprintf(stderr, "Enter Y or N\n");
480			}
481		}
482		/*NOTREACHED*/
483	case -2:
484	abandon:
485		fprintf(stderr, "%s: edits left in %s\n",
486			ProgramName, Filename);
487		goto done;
488	default:
489		fprintf(stderr, "%s: panic: bad switch() in replace_cmd()\n",
490		    ProgramName);
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 */
504static int
505replace_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		fprintf(stderr, "%s: Cannot allocate memory.\n", ProgramName);
515		return (-2);
516	}
517
518	(void) sprintf(n, "tmp.%d", Pid);
519	(void) sprintf(tn, CRON_TAB(n));
520	if (!(tmp = fopen(tn, "w+"))) {
521		perror(tn);
522		return (-2);
523	}
524
525	/* write a signature at the top of the file.
526	 *
527	 * VERY IMPORTANT: make sure NHEADER_LINES agrees with this code.
528	 */
529	fprintf(tmp, "# DO NOT EDIT THIS FILE - edit the master and reinstall.\n");
530	fprintf(tmp, "# (%s installed on %-24.24s)\n", Filename, ctime(&now));
531	fprintf(tmp, "# (Cron version -- %s)\n", rcsid);
532
533	/* copy the crontab to the tmp
534	 */
535	Set_LineNum(1)
536	while (EOF != (ch = get_char(NewCrontab)))
537		putc(ch, tmp);
538	fclose(NewCrontab);
539	ftruncate(fileno(tmp), ftell(tmp));
540	fflush(tmp);  rewind(tmp);
541
542	if (ferror(tmp)) {
543		fprintf(stderr, "%s: error while writing new crontab to %s\n",
544			ProgramName, 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(e);
567			break;
568		case TRUE:
569			break;
570		}
571	}
572
573	if (CheckErrorCount != 0) {
574		fprintf(stderr, "errors in crontab file, can't install.\n");
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		perror("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		perror("chown");
597		fclose(tmp);  unlink(tn);
598		return (-2);
599	}
600
601	if (fclose(tmp) == EOF) {
602		perror("fclose");
603		unlink(tn);
604		return (-2);
605	}
606
607	(void) sprintf(n, CRON_TAB(User));
608	if (rename(tn, n)) {
609		fprintf(stderr, "%s: error renaming %s to %s\n",
610			ProgramName, tn, n);
611		perror("rename");
612		unlink(tn);
613		return (-2);
614	}
615	log_it(RealUser, Pid, "REPLACE", User);
616
617	poke_daemon();
618
619	return (0);
620}
621
622
623static void
624poke_daemon() {
625#ifdef USE_UTIMES
626	struct timeval tvs[2];
627	struct timezone tz;
628
629	(void) gettimeofday(&tvs[0], &tz);
630	tvs[1] = tvs[0];
631	if (utimes(SPOOL_DIR, tvs) < OK) {
632		fprintf(stderr, "crontab: can't update mtime on spooldir\n");
633		perror(SPOOL_DIR);
634		return;
635	}
636#else
637	if (utime(SPOOL_DIR, NULL) < OK) {
638		fprintf(stderr, "crontab: can't update mtime on spooldir\n");
639		perror(SPOOL_DIR);
640		return;
641	}
642#endif /*USE_UTIMES*/
643}
644