crontab.c revision 8857 
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 1.2 1994/12/21 11:06:08 ache 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
29#define	MAIN_PROGRAM
30
31
32#include "cron.h"
33#include <errno.h>
34#include <fcntl.h>
35#include <sys/file.h>
36#include <sys/stat.h>
37#ifdef USE_UTIMES
38# include <sys/time.h>
39#else
40# include <time.h>
41# include <utime.h>
42#endif
43#if defined(POSIX)
44# include <locale.h>
45#endif
46
47
48#define NHEADER_LINES 3
49
50
51enum opt_t	{ opt_unknown, opt_list, opt_delete, opt_edit, opt_replace };
52
53#if DEBUGGING
54static char	*Options[] = { "???", "list", "delete", "edit", "replace" };
55#endif
56
57
58static	PID_T		Pid;
59static	char		User[MAX_UNAME], RealUser[MAX_UNAME];
60static	char		Filename[MAX_FNAME];
61static	FILE		*NewCrontab;
62static	int		CheckErrorCount;
63static	enum opt_t	Option;
64static	struct passwd	*pw;
65static	void		list_cmd __P((void)),
66			delete_cmd __P((void)),
67			edit_cmd __P((void)),
68			poke_daemon __P((void)),
69			check_error __P((char *)),
70			parse_args __P((int c, char *v[]));
71static	int		replace_cmd __P((void));
72
73
74static void
75usage(msg)
76	char *msg;
77{
78	fprintf(stderr, "%s: usage error: %s\n", ProgramName, msg);
79	fprintf(stderr, "usage:\t%s [-u user] file\n", ProgramName);
80	fprintf(stderr, "\t%s [-u user] { -e | -l | -r }\n", ProgramName);
81	fprintf(stderr, "\t\t(default operation is replace, per 1003.2)\n");
82	fprintf(stderr, "\t-e\t(edit user's crontab)\n");
83	fprintf(stderr, "\t-l\t(list user's crontab)\n");
84	fprintf(stderr, "\t-r\t(delete user's crontab)\n");
85	exit(ERROR_EXIT);
86}
87
88
89int
90main(argc, argv)
91	int	argc;
92	char	*argv[];
93{
94	int	exitstatus;
95
96	Pid = getpid();
97	ProgramName = argv[0];
98
99#if defined(POSIX)
100	setlocale(LC_ALL, "");
101#endif
102
103#if defined(BSD)
104	setlinebuf(stderr);
105#endif
106	parse_args(argc, argv);		/* sets many globals, opens a file */
107	set_cron_uid();
108	set_cron_cwd();
109	if (!allowed(User)) {
110		fprintf(stderr,
111			"You (%s) are not allowed to use this program (%s)\n",
112			User, ProgramName);
113		fprintf(stderr, "See crontab(1) for more information\n");
114		log_it(RealUser, Pid, "AUTH", "crontab command not allowed");
115		exit(ERROR_EXIT);
116	}
117	exitstatus = OK_EXIT;
118	switch (Option) {
119	case opt_list:		list_cmd();
120				break;
121	case opt_delete:	delete_cmd();
122				break;
123	case opt_edit:		edit_cmd();
124				break;
125	case opt_replace:	if (replace_cmd() < 0)
126					exitstatus = ERROR_EXIT;
127				break;
128	}
129	exit(0);
130	/*NOTREACHED*/
131}
132
133
134static void
135parse_args(argc, argv)
136	int	argc;
137	char	*argv[];
138{
139	int		argch;
140
141	if (!(pw = getpwuid(getuid()))) {
142		fprintf(stderr, "%s: your UID isn't in the passwd file.\n",
143			ProgramName);
144		fprintf(stderr, "bailing out.\n");
145		exit(ERROR_EXIT);
146	}
147	strcpy(User, pw->pw_name);
148	strcpy(RealUser, User);
149	Filename[0] = '\0';
150	Option = opt_unknown;
151	while (EOF != (argch = getopt(argc, argv, "u:lerx:"))) {
152		switch (argch) {
153		case 'x':
154			if (!set_debug_flags(optarg))
155				usage("bad debug option");
156			break;
157		case 'u':
158			if (getuid() != ROOT_UID)
159			{
160				fprintf(stderr,
161					"must be privileged to use -u\n");
162				exit(ERROR_EXIT);
163			}
164			if (!(pw = getpwnam(optarg)))
165			{
166				fprintf(stderr, "%s:  user `%s' unknown\n",
167					ProgramName, optarg);
168				exit(ERROR_EXIT);
169			}
170			(void) strcpy(User, optarg);
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) strcpy (Filename, argv[optind]);
202		} else {
203			usage("file name must be specified for replace");
204		}
205	}
206
207	if (Option == opt_replace) {
208		/* we have to open the file here because we're going to
209		 * chdir(2) into /var/cron before we get around to
210		 * reading the file.
211		 */
212		if (!strcmp(Filename, "-")) {
213			NewCrontab = stdin;
214		} else {
215			/* relinquish the setuid status of the binary during
216			 * the open, lest nonroot users read files they should
217			 * not be able to read.  we can't use access() here
218			 * since there's a race condition.  thanks go out to
219			 * Arnt Gulbrandsen <agulbra@pvv.unit.no> for spotting
220			 * the race.
221			 */
222
223			if (swap_uids() < OK) {
224				perror("swapping uids");
225				exit(ERROR_EXIT);
226			}
227			if (!(NewCrontab = fopen(Filename, "r"))) {
228				perror(Filename);
229				exit(ERROR_EXIT);
230			}
231			if (swap_uids() < OK) {
232				perror("swapping uids back");
233				exit(ERROR_EXIT);
234			}
235		}
236	}
237
238	Debug(DMISC, ("user=%s, file=%s, option=%s\n",
239		      User, Filename, Options[(int)Option]))
240}
241
242
243static void
244list_cmd() {
245	char	n[MAX_FNAME];
246	FILE	*f;
247	int	ch;
248
249	log_it(RealUser, Pid, "LIST", User);
250	(void) sprintf(n, CRON_TAB(User));
251	if (!(f = fopen(n, "r"))) {
252		if (errno == ENOENT)
253			fprintf(stderr, "no crontab for %s\n", User);
254		else
255			perror(n);
256		exit(ERROR_EXIT);
257	}
258
259	/* file is open. copy to stdout, close.
260	 */
261	Set_LineNum(1)
262	while (EOF != (ch = get_char(f)))
263		putchar(ch);
264	fclose(f);
265}
266
267
268static void
269delete_cmd() {
270	char	n[MAX_FNAME];
271
272	log_it(RealUser, Pid, "DELETE", User);
273	(void) sprintf(n, CRON_TAB(User));
274	if (unlink(n)) {
275		if (errno == ENOENT)
276			fprintf(stderr, "no crontab for %s\n", User);
277		else
278			perror(n);
279		exit(ERROR_EXIT);
280	}
281	poke_daemon();
282}
283
284
285static void
286check_error(msg)
287	char	*msg;
288{
289	CheckErrorCount++;
290	fprintf(stderr, "\"%s\":%d: %s\n", Filename, LineNumber-1, msg);
291}
292
293
294static void
295edit_cmd() {
296	char		n[MAX_FNAME], q[MAX_TEMPSTR], *editor;
297	FILE		*f;
298	int		ch, t, x;
299	struct stat	statbuf;
300	time_t		mtime;
301	WAIT_T		waiter;
302	PID_T		pid, xpid;
303
304	log_it(RealUser, Pid, "BEGIN EDIT", User);
305	(void) sprintf(n, CRON_TAB(User));
306	if (!(f = fopen(n, "r"))) {
307		if (errno != ENOENT) {
308			perror(n);
309			exit(ERROR_EXIT);
310		}
311		fprintf(stderr, "no crontab for %s - using an empty one\n",
312			User);
313		if (!(f = fopen("/dev/null", "r"))) {
314			perror("/dev/null");
315			exit(ERROR_EXIT);
316		}
317	}
318
319	(void) sprintf(Filename, "/tmp/crontab.%d", Pid);
320	if (-1 == (t = open(Filename, O_CREAT|O_EXCL|O_RDWR, 0600))) {
321		perror(Filename);
322		goto fatal;
323	}
324#ifdef HAS_FCHOWN
325	if (fchown(t, getuid(), getgid()) < 0) {
326#else
327	if (chown(Filename, getuid(), getgid()) < 0) {
328#endif
329		perror("fchown");
330		goto fatal;
331	}
332	if (!(NewCrontab = fdopen(t, "w"))) {
333		perror("fdopen");
334		goto fatal;
335	}
336
337	Set_LineNum(1)
338
339	/* ignore the top few comments since we probably put them there.
340	 */
341	for (x = 0;  x < NHEADER_LINES;  x++) {
342		ch = get_char(f);
343		if (EOF == ch)
344			break;
345		if ('#' != ch) {
346			putc(ch, NewCrontab);
347			break;
348		}
349		while (EOF != (ch = get_char(f)))
350			if (ch == '\n')
351				break;
352		if (EOF == ch)
353			break;
354	}
355
356	/* copy the rest of the crontab (if any) to the temp file.
357	 */
358	if (EOF != ch)
359		while (EOF != (ch = get_char(f)))
360			putc(ch, NewCrontab);
361	fclose(f);
362	if (fclose(NewCrontab)) {
363		perror(Filename);
364		exit(ERROR_EXIT);
365	}
366 again:
367	if (stat(Filename, &statbuf) < 0) {
368		perror("stat");
369 fatal:		unlink(Filename);
370		exit(ERROR_EXIT);
371	}
372	mtime = statbuf.st_mtime;
373
374	if ((!(editor = getenv("VISUAL")))
375	 && (!(editor = getenv("EDITOR")))
376	    ) {
377		editor = EDITOR;
378	}
379
380	/* we still have the file open.  editors will generally rewrite the
381	 * original file rather than renaming/unlinking it and starting a
382	 * new one; even backup files are supposed to be made by copying
383	 * rather than by renaming.  if some editor does not support this,
384	 * then don't use it.  the security problems are more severe if we
385	 * close and reopen the file around the edit.
386	 */
387
388	switch (pid = fork()) {
389	case -1:
390		perror("fork");
391		goto fatal;
392	case 0:
393		/* child */
394		if (setuid(getuid()) < 0) {
395			perror("setuid(getuid())");
396			exit(ERROR_EXIT);
397		}
398		if (chdir("/tmp") < 0) {
399			perror("chdir(/tmp)");
400			exit(ERROR_EXIT);
401		}
402		if (strlen(editor) + strlen(Filename) + 2 >= MAX_TEMPSTR) {
403			fprintf(stderr, "%s: editor or filename too long\n",
404				ProgramName);
405			exit(ERROR_EXIT);
406		}
407		sprintf(q, "%s %s", editor, Filename);
408		execlp(_PATH_BSHELL, _PATH_BSHELL, "-c", q, NULL);
409		perror(editor);
410		exit(ERROR_EXIT);
411		/*NOTREACHED*/
412	default:
413		/* parent */
414		break;
415	}
416
417	/* parent */
418	xpid = wait(&waiter);
419	if (xpid != pid) {
420		fprintf(stderr, "%s: wrong PID (%d != %d) from \"%s\"\n",
421			ProgramName, xpid, pid, editor);
422		goto fatal;
423	}
424	if (WIFEXITED(waiter) && WEXITSTATUS(waiter)) {
425		fprintf(stderr, "%s: \"%s\" exited with status %d\n",
426			ProgramName, editor, WEXITSTATUS(waiter));
427		goto fatal;
428	}
429	if (WIFSIGNALED(waiter)) {
430		fprintf(stderr,
431			"%s: \"%s\" killed; signal %d (%score dumped)\n",
432			ProgramName, editor, WTERMSIG(waiter),
433			WCOREDUMP(waiter) ?"" :"no ");
434		goto fatal;
435	}
436	if (stat(Filename, &statbuf) < 0) {
437		perror("stat");
438		goto fatal;
439	}
440	if (mtime == statbuf.st_mtime) {
441		fprintf(stderr, "%s: no changes made to crontab\n",
442			ProgramName);
443		goto remove;
444	}
445	fprintf(stderr, "%s: installing new crontab\n", ProgramName);
446	if (!(NewCrontab = fopen(Filename, "r"))) {
447		perror(Filename);
448		goto fatal;
449	}
450	switch (replace_cmd()) {
451	case 0:
452		break;
453	case -1:
454		for (;;) {
455			printf("Do you want to retry the same edit? ");
456			fflush(stdout);
457			q[0] = '\0';
458			(void) fgets(q, sizeof q, stdin);
459			switch (islower(q[0]) ? q[0] : tolower(q[0])) {
460			case 'y':
461				goto again;
462			case 'n':
463				goto abandon;
464			default:
465				fprintf(stderr, "Enter Y or N\n");
466			}
467		}
468		/*NOTREACHED*/
469	case -2:
470	abandon:
471		fprintf(stderr, "%s: edits left in %s\n",
472			ProgramName, Filename);
473		goto done;
474	default:
475		fprintf(stderr, "%s: panic: bad switch() in replace_cmd()\n");
476		goto fatal;
477	}
478 remove:
479	unlink(Filename);
480 done:
481	log_it(RealUser, Pid, "END EDIT", User);
482}
483
484
485/* returns	0	on success
486 *		-1	on syntax error
487 *		-2	on install error
488 */
489static int
490replace_cmd() {
491	char	n[MAX_FNAME], envstr[MAX_ENVSTR], tn[MAX_FNAME];
492	FILE	*tmp;
493	int	ch, eof;
494	entry	*e;
495	time_t	now = time(NULL);
496	char	**envp = env_init();
497
498	(void) sprintf(n, "tmp.%d", Pid);
499	(void) sprintf(tn, CRON_TAB(n));
500	if (!(tmp = fopen(tn, "w+"))) {
501		perror(tn);
502		return (-2);
503	}
504
505	/* write a signature at the top of the file.
506	 *
507	 * VERY IMPORTANT: make sure NHEADER_LINES agrees with this code.
508	 */
509	fprintf(tmp, "# DO NOT EDIT THIS FILE - edit the master and reinstall.\n");
510	fprintf(tmp, "# (%s installed on %-24.24s)\n", Filename, ctime(&now));
511	fprintf(tmp, "# (Cron version -- %s)\n", rcsid);
512
513	/* copy the crontab to the tmp
514	 */
515	Set_LineNum(1)
516	while (EOF != (ch = get_char(NewCrontab)))
517		putc(ch, tmp);
518	fclose(NewCrontab);
519	ftruncate(fileno(tmp), ftell(tmp));
520	fflush(tmp);  rewind(tmp);
521
522	if (ferror(tmp)) {
523		fprintf(stderr, "%s: error while writing new crontab to %s\n",
524			ProgramName, tn);
525		fclose(tmp);  unlink(tn);
526		return (-2);
527	}
528
529	/* check the syntax of the file being installed.
530	 */
531
532	/* BUG: was reporting errors after the EOF if there were any errors
533	 * in the file proper -- kludged it by stopping after first error.
534	 *		vix 31mar87
535	 */
536	Set_LineNum(1 - NHEADER_LINES)
537	CheckErrorCount = 0;  eof = FALSE;
538	while (!CheckErrorCount && !eof) {
539		switch (load_env(envstr, tmp)) {
540		case ERR:
541			eof = TRUE;
542			break;
543		case FALSE:
544			e = load_entry(tmp, check_error, pw, envp);
545			if (e)
546				free(e);
547			break;
548		case TRUE:
549			break;
550		}
551	}
552
553	if (CheckErrorCount != 0) {
554		fprintf(stderr, "errors in crontab file, can't install.\n");
555		fclose(tmp);  unlink(tn);
556		return (-1);
557	}
558
559#ifdef HAS_FCHOWN
560	if (fchown(fileno(tmp), ROOT_UID, -1) < OK)
561#else
562	if (chown(tn, ROOT_UID, -1) < OK)
563#endif
564	{
565		perror("chown");
566		fclose(tmp);  unlink(tn);
567		return (-2);
568	}
569
570#ifdef HAS_FCHMOD
571	if (fchmod(fileno(tmp), 0600) < OK)
572#else
573	if (chmod(tn, 0600) < OK)
574#endif
575	{
576		perror("chown");
577		fclose(tmp);  unlink(tn);
578		return (-2);
579	}
580
581	if (fclose(tmp) == EOF) {
582		perror("fclose");
583		unlink(tn);
584		return (-2);
585	}
586
587	(void) sprintf(n, CRON_TAB(User));
588	if (rename(tn, n)) {
589		fprintf(stderr, "%s: error renaming %s to %s\n",
590			ProgramName, tn, n);
591		perror("rename");
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
603static void
604poke_daemon() {
605#ifdef USE_UTIMES
606	struct timeval tvs[2];
607	struct timezone tz;
608
609	(void) gettimeofday(&tvs[0], &tz);
610	tvs[1] = tvs[0];
611	if (utimes(SPOOL_DIR, tvs) < OK) {
612		fprintf(stderr, "crontab: can't update mtime on spooldir\n");
613		perror(SPOOL_DIR);
614		return;
615	}
616#else
617	if (utime(SPOOL_DIR, NULL) < OK) {
618		fprintf(stderr, "crontab: can't update mtime on spooldir\n");
619		perror(SPOOL_DIR);
620		return;
621	}
622#endif /*USE_UTIMES*/
623}
624