crontab.c revision 2311 
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
18#if !defined(lint) && !defined(LINT)
19static char rcsid[] = "$Id: crontab.c,v 2.13 1994/01/17 03:20:37 vixie Exp $";
20#endif
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
28#define	MAIN_PROGRAM
29
30
31#include "cron.h"
32#include <errno.h>
33#include <fcntl.h>
34#include <sys/file.h>
35#include <sys/stat.h>
36#ifdef USE_UTIMES
37# include <sys/time.h>
38#else
39# include <time.h>
40# include <utime.h>
41#endif
42#if defined(POSIX)
43# include <locale.h>
44#endif
45
46
47#define NHEADER_LINES 3
48
49
50enum opt_t	{ opt_unknown, opt_list, opt_delete, opt_edit, opt_replace };
51
52#if DEBUGGING
53static char	*Options[] = { "???", "list", "delete", "edit", "replace" };
54#endif
55
56
57static	PID_T		Pid;
58static	char		User[MAX_UNAME], RealUser[MAX_UNAME];
59static	char		Filename[MAX_FNAME];
60static	FILE		*NewCrontab;
61static	int		CheckErrorCount;
62static	enum opt_t	Option;
63static	struct passwd	*pw;
64static	void		list_cmd __P((void)),
65			delete_cmd __P((void)),
66			edit_cmd __P((void)),
67			poke_daemon __P((void)),
68			check_error __P((char *)),
69			parse_args __P((int c, char *v[]));
70static	int		replace_cmd __P((void));
71
72
73static void
74usage(msg)
75	char *msg;
76{
77	fprintf(stderr, "%s: usage error: %s\n", ProgramName, msg);
78	fprintf(stderr, "usage:\t%s [-u user] file\n", ProgramName);
79	fprintf(stderr, "\t%s [-u user] { -e | -l | -r }\n", ProgramName);
80	fprintf(stderr, "\t\t(default operation is replace, per 1003.2)\n");
81	fprintf(stderr, "\t-e\t(edit user's crontab)\n");
82	fprintf(stderr, "\t-l\t(list user's crontab)\n");
83	fprintf(stderr, "\t-r\t(delete user's crontab)\n");
84	exit(ERROR_EXIT);
85}
86
87
88int
89main(argc, argv)
90	int	argc;
91	char	*argv[];
92{
93	int	exitstatus;
94
95	Pid = getpid();
96	ProgramName = argv[0];
97
98#if defined(POSIX)
99	setlocale(LC_ALL, "");
100#endif
101
102#if defined(BSD)
103	setlinebuf(stderr);
104#endif
105	parse_args(argc, argv);		/* sets many globals, opens a file */
106	set_cron_uid();
107	set_cron_cwd();
108	if (!allowed(User)) {
109		fprintf(stderr,
110			"You (%s) are not allowed to use this program (%s)\n",
111			User, ProgramName);
112		fprintf(stderr, "See crontab(1) for more information\n");
113		log_it(RealUser, Pid, "AUTH", "crontab command not allowed");
114		exit(ERROR_EXIT);
115	}
116	exitstatus = OK_EXIT;
117	switch (Option) {
118	case opt_list:		list_cmd();
119				break;
120	case opt_delete:	delete_cmd();
121				break;
122	case opt_edit:		edit_cmd();
123				break;
124	case opt_replace:	if (replace_cmd() < 0)
125					exitstatus = ERROR_EXIT;
126				break;
127	}
128	exit(0);
129	/*NOTREACHED*/
130}
131
132
133static void
134parse_args(argc, argv)
135	int	argc;
136	char	*argv[];
137{
138	int		argch;
139
140	if (!(pw = getpwuid(getuid()))) {
141		fprintf(stderr, "%s: your UID isn't in the passwd file.\n",
142			ProgramName);
143		fprintf(stderr, "bailing out.\n");
144		exit(ERROR_EXIT);
145	}
146	strcpy(User, pw->pw_name);
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) strcpy(User, optarg);
170			break;
171		case 'l':
172			if (Option != opt_unknown)
173				usage("only one operation permitted");
174			Option = opt_list;
175			break;
176		case 'r':
177			if (Option != opt_unknown)
178				usage("only one operation permitted");
179			Option = opt_delete;
180			break;
181		case 'e':
182			if (Option != opt_unknown)
183				usage("only one operation permitted");
184			Option = opt_edit;
185			break;
186		default:
187			usage("unrecognized option");
188		}
189	}
190
191	endpwent();
192
193	if (Option != opt_unknown) {
194		if (argv[optind] != NULL) {
195			usage("no arguments permitted after this option");
196		}
197	} else {
198		if (argv[optind] != NULL) {
199			Option = opt_replace;
200			(void) strcpy (Filename, argv[optind]);
201		} else {
202			usage("file name must be specified for replace");
203		}
204	}
205
206	if (Option == opt_replace) {
207		/* we have to open the file here because we're going to
208		 * chdir(2) into /var/cron before we get around to
209		 * reading the file.
210		 */
211		if (!strcmp(Filename, "-")) {
212			NewCrontab = stdin;
213		} else {
214			/* relinquish the setuid status of the binary during
215			 * the open, lest nonroot users read files they should
216			 * not be able to read.  we can't use access() here
217			 * since there's a race condition.  thanks go out to
218			 * Arnt Gulbrandsen <agulbra@pvv.unit.no> for spotting
219			 * the race.
220			 */
221
222			if (swap_uids() < OK) {
223				perror("swapping uids");
224				exit(ERROR_EXIT);
225			}
226			if (!(NewCrontab = fopen(Filename, "r"))) {
227				perror(Filename);
228				exit(ERROR_EXIT);
229			}
230			if (swap_uids() < OK) {
231				perror("swapping uids back");
232				exit(ERROR_EXIT);
233			}
234		}
235	}
236
237	Debug(DMISC, ("user=%s, file=%s, option=%s\n",
238		      User, Filename, Options[(int)Option]))
239}
240
241
242static void
243list_cmd() {
244	char	n[MAX_FNAME];
245	FILE	*f;
246	int	ch;
247
248	log_it(RealUser, Pid, "LIST", User);
249	(void) sprintf(n, CRON_TAB(User));
250	if (!(f = fopen(n, "r"))) {
251		if (errno == ENOENT)
252			fprintf(stderr, "no crontab for %s\n", User);
253		else
254			perror(n);
255		exit(ERROR_EXIT);
256	}
257
258	/* file is open. copy to stdout, close.
259	 */
260	Set_LineNum(1)
261	while (EOF != (ch = get_char(f)))
262		putchar(ch);
263	fclose(f);
264}
265
266
267static void
268delete_cmd() {
269	char	n[MAX_FNAME];
270
271	log_it(RealUser, Pid, "DELETE", User);
272	(void) sprintf(n, CRON_TAB(User));
273	if (unlink(n)) {
274		if (errno == ENOENT)
275			fprintf(stderr, "no crontab for %s\n", User);
276		else
277			perror(n);
278		exit(ERROR_EXIT);
279	}
280	poke_daemon();
281}
282
283
284static void
285check_error(msg)
286	char	*msg;
287{
288	CheckErrorCount++;
289	fprintf(stderr, "\"%s\":%d: %s\n", Filename, LineNumber-1, msg);
290}
291
292
293static void
294edit_cmd() {
295	char		n[MAX_FNAME], q[MAX_TEMPSTR], *editor;
296	FILE		*f;
297	int		ch, t, x;
298	struct stat	statbuf;
299	time_t		mtime;
300	WAIT_T		waiter;
301	PID_T		pid, xpid;
302
303	log_it(RealUser, Pid, "BEGIN EDIT", User);
304	(void) sprintf(n, CRON_TAB(User));
305	if (!(f = fopen(n, "r"))) {
306		if (errno != ENOENT) {
307			perror(n);
308			exit(ERROR_EXIT);
309		}
310		fprintf(stderr, "no crontab for %s - using an empty one\n",
311			User);
312		if (!(f = fopen("/dev/null", "r"))) {
313			perror("/dev/null");
314			exit(ERROR_EXIT);
315		}
316	}
317
318	(void) sprintf(Filename, "/tmp/crontab.%d", Pid);
319	if (-1 == (t = open(Filename, O_CREAT|O_EXCL|O_RDWR, 0600))) {
320		perror(Filename);
321		goto fatal;
322	}
323#ifdef HAS_FCHOWN
324	if (fchown(t, getuid(), getgid()) < 0) {
325#else
326	if (chown(Filename, getuid(), getgid()) < 0) {
327#endif
328		perror("fchown");
329		goto fatal;
330	}
331	if (!(NewCrontab = fdopen(t, "r+"))) {
332		perror("fdopen");
333		goto fatal;
334	}
335
336	Set_LineNum(1)
337
338	/* ignore the top few comments since we probably put them there.
339	 */
340	for (x = 0;  x < NHEADER_LINES;  x++) {
341		ch = get_char(f);
342		if (EOF == ch)
343			break;
344		if ('#' != ch) {
345			putc(ch, NewCrontab);
346			break;
347		}
348		while (EOF != (ch = get_char(f)))
349			if (ch == '\n')
350				break;
351		if (EOF == ch)
352			break;
353	}
354
355	/* copy the rest of the crontab (if any) to the temp file.
356	 */
357	if (EOF != ch)
358		while (EOF != (ch = get_char(f)))
359			putc(ch, NewCrontab);
360	fclose(f);
361	if (fflush(NewCrontab) < OK) {
362		perror(Filename);
363		exit(ERROR_EXIT);
364	}
365 again:
366	rewind(NewCrontab);
367	if (ferror(NewCrontab)) {
368		fprintf(stderr, "%s: error while writing new crontab to %s\n",
369			ProgramName, Filename);
370 fatal:		unlink(Filename);
371		exit(ERROR_EXIT);
372	}
373	if (fstat(t, &statbuf) < 0) {
374		perror("fstat");
375		goto fatal;
376	}
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		perror("fork");
396		goto fatal;
397	case 0:
398		/* child */
399		if (setuid(getuid()) < 0) {
400			perror("setuid(getuid())");
401			exit(ERROR_EXIT);
402		}
403		if (chdir("/tmp") < 0) {
404			perror("chdir(/tmp)");
405			exit(ERROR_EXIT);
406		}
407		if (strlen(editor) + strlen(Filename) + 2 >= MAX_TEMPSTR) {
408			fprintf(stderr, "%s: editor or filename too long\n",
409				ProgramName);
410			exit(ERROR_EXIT);
411		}
412		sprintf(q, "%s %s", editor, Filename);
413		execlp(_PATH_BSHELL, _PATH_BSHELL, "-c", q, NULL);
414		perror(editor);
415		exit(ERROR_EXIT);
416		/*NOTREACHED*/
417	default:
418		/* parent */
419		break;
420	}
421
422	/* parent */
423	xpid = wait(&waiter);
424	if (xpid != pid) {
425		fprintf(stderr, "%s: wrong PID (%d != %d) from \"%s\"\n",
426			ProgramName, xpid, pid, editor);
427		goto fatal;
428	}
429	if (WIFEXITED(waiter) && WEXITSTATUS(waiter)) {
430		fprintf(stderr, "%s: \"%s\" exited with status %d\n",
431			ProgramName, editor, WEXITSTATUS(waiter));
432		goto fatal;
433	}
434	if (WIFSIGNALED(waiter)) {
435		fprintf(stderr,
436			"%s: \"%s\" killed; signal %d (%score dumped)\n",
437			ProgramName, editor, WTERMSIG(waiter),
438			WCOREDUMP(waiter) ?"" :"no ");
439		goto fatal;
440	}
441	if (fstat(t, &statbuf) < 0) {
442		perror("fstat");
443		goto fatal;
444	}
445	if (mtime == statbuf.st_mtime) {
446		fprintf(stderr, "%s: no changes made to crontab\n",
447			ProgramName);
448		goto remove;
449	}
450	fprintf(stderr, "%s: installing new crontab\n", ProgramName);
451	switch (replace_cmd()) {
452	case 0:
453		break;
454	case -1:
455		for (;;) {
456			printf("Do you want to retry the same edit? ");
457			fflush(stdout);
458			q[0] = '\0';
459			(void) fgets(q, sizeof q, stdin);
460			switch (islower(q[0]) ? q[0] : tolower(q[0])) {
461			case 'y':
462				goto again;
463			case 'n':
464				goto abandon;
465			default:
466				fprintf(stderr, "Enter Y or N\n");
467			}
468		}
469		/*NOTREACHED*/
470	case -2:
471	abandon:
472		fprintf(stderr, "%s: edits left in %s\n",
473			ProgramName, Filename);
474		goto done;
475	default:
476		fprintf(stderr, "%s: panic: bad switch() in replace_cmd()\n");
477		goto fatal;
478	}
479 remove:
480	unlink(Filename);
481 done:
482	log_it(RealUser, Pid, "END EDIT", User);
483}
484
485
486/* returns	0	on success
487 *		-1	on syntax error
488 *		-2	on install error
489 */
490static int
491replace_cmd() {
492	char	n[MAX_FNAME], envstr[MAX_ENVSTR], tn[MAX_FNAME];
493	FILE	*tmp;
494	int	ch, eof;
495	entry	*e;
496	time_t	now = time(NULL);
497	char	**envp = env_init();
498
499	(void) sprintf(n, "tmp.%d", Pid);
500	(void) sprintf(tn, CRON_TAB(n));
501	if (!(tmp = fopen(tn, "w+"))) {
502		perror(tn);
503		return (-2);
504	}
505
506	/* write a signature at the top of the file.
507	 *
508	 * VERY IMPORTANT: make sure NHEADER_LINES agrees with this code.
509	 */
510	fprintf(tmp, "# DO NOT EDIT THIS FILE - edit the master and reinstall.\n");
511	fprintf(tmp, "# (%s installed on %-24.24s)\n", Filename, ctime(&now));
512	fprintf(tmp, "# (Cron version -- %s)\n", rcsid);
513
514	/* copy the crontab to the tmp
515	 */
516	rewind(NewCrontab);
517	Set_LineNum(1)
518	while (EOF != (ch = get_char(NewCrontab)))
519		putc(ch, tmp);
520	ftruncate(fileno(tmp), ftell(tmp));
521	fflush(tmp);  rewind(tmp);
522
523	if (ferror(tmp)) {
524		fprintf(stderr, "%s: error while writing new crontab to %s\n",
525			ProgramName, 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		fprintf(stderr, "errors in crontab file, can't install.\n");
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		perror("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		perror("chown");
578		fclose(tmp);  unlink(tn);
579		return (-2);
580	}
581
582	if (fclose(tmp) == EOF) {
583		perror("fclose");
584		unlink(tn);
585		return (-2);
586	}
587
588	(void) sprintf(n, CRON_TAB(User));
589	if (rename(tn, n)) {
590		fprintf(stderr, "%s: error renaming %s to %s\n",
591			ProgramName, tn, n);
592		perror("rename");
593		unlink(tn);
594		return (-2);
595	}
596	log_it(RealUser, Pid, "REPLACE", User);
597
598	poke_daemon();
599
600	return (0);
601}
602
603
604static void
605poke_daemon() {
606#ifdef USE_UTIMES
607	struct timeval tvs[2];
608	struct timezone tz;
609
610	(void) gettimeofday(&tvs[0], &tz);
611	tvs[1] = tvs[0];
612	if (utimes(SPOOL_DIR, tvs) < OK) {
613		fprintf(stderr, "crontab: can't update mtime on spooldir\n");
614		perror(SPOOL_DIR);
615		return;
616	}
617#else
618	if (utime(SPOOL_DIR, NULL) < OK) {
619		fprintf(stderr, "crontab: can't update mtime on spooldir\n");
620		perror(SPOOL_DIR);
621		return;
622	}
623#endif /*USE_UTIMES*/
624}
625