crontab.c revision 135242 
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 const char rcsid[] =
21  "$FreeBSD: head/usr.sbin/cron/crontab/crontab.c 135242 2004-09-14 19:01:19Z dds $";
22#endif
23
24/* crontab - install and manage per-user crontab files
25 * vix 02may87 [RCS has the rest of the log]
26 * vix 26jan87 [original]
27 */
28
29#define	MAIN_PROGRAM
30
31#include "cron.h"
32#include <errno.h>
33#include <fcntl.h>
34#include <md5.h>
35#include <paths.h>
36#include <sys/file.h>
37#include <sys/stat.h>
38#ifdef USE_UTIMES
39# include <sys/time.h>
40#else
41# include <time.h>
42# include <utime.h>
43#endif
44#if defined(POSIX)
45# include <locale.h>
46#endif
47
48#define MD5_SIZE 33
49#define NHEADER_LINES 3
50
51
52enum opt_t	{ opt_unknown, opt_list, opt_delete, opt_edit, opt_replace };
53
54#if DEBUGGING
55static char	*Options[] = { "???", "list", "delete", "edit", "replace" };
56#endif
57
58
59static	PID_T		Pid;
60static	char		User[MAX_UNAME], RealUser[MAX_UNAME];
61static	char		Filename[MAX_FNAME];
62static	FILE		*NewCrontab;
63static	int		CheckErrorCount;
64static	enum opt_t	Option;
65static	struct passwd	*pw;
66static	void		list_cmd __P((void)),
67			delete_cmd __P((void)),
68			edit_cmd __P((void)),
69			poke_daemon __P((void)),
70			check_error __P((char *)),
71			parse_args __P((int c, char *v[]));
72static	int		replace_cmd __P((void));
73
74
75static void
76usage(msg)
77	char *msg;
78{
79	fprintf(stderr, "crontab: usage error: %s\n", msg);
80	fprintf(stderr, "%s\n%s\n",
81		"usage: crontab [-u user] file",
82		"       crontab [-u user] { -e | -l | -r }");
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		warnx("you (%s) are not allowed to use this program", User);
109		log_it(RealUser, Pid, "AUTH", "crontab command not allowed");
110		exit(ERROR_EXIT);
111	}
112	exitstatus = OK_EXIT;
113	switch (Option) {
114	case opt_list:		list_cmd();
115				break;
116	case opt_delete:	delete_cmd();
117				break;
118	case opt_edit:		edit_cmd();
119				break;
120	case opt_replace:	if (replace_cmd() < 0)
121					exitstatus = ERROR_EXIT;
122				break;
123	case opt_unknown:
124				break;
125	}
126	exit(exitstatus);
127	/*NOTREACHED*/
128}
129
130
131static void
132parse_args(argc, argv)
133	int	argc;
134	char	*argv[];
135{
136	int		argch;
137
138	if (!(pw = getpwuid(getuid())))
139		errx(ERROR_EXIT, "your UID isn't in the passwd file, bailing out");
140	(void) strncpy(User, pw->pw_name, (sizeof User)-1);
141	User[(sizeof User)-1] = '\0';
142	strcpy(RealUser, User);
143	Filename[0] = '\0';
144	Option = opt_unknown;
145	while ((argch = getopt(argc, argv, "u:lerx:")) != -1) {
146		switch (argch) {
147		case 'x':
148			if (!set_debug_flags(optarg))
149				usage("bad debug option");
150			break;
151		case 'u':
152			if (getuid() != ROOT_UID)
153				errx(ERROR_EXIT, "must be privileged to use -u");
154			if (!(pw = getpwnam(optarg)))
155				errx(ERROR_EXIT, "user `%s' unknown", optarg);
156			(void) strncpy(User, pw->pw_name, (sizeof User)-1);
157			User[(sizeof User)-1] = '\0';
158			break;
159		case 'l':
160			if (Option != opt_unknown)
161				usage("only one operation permitted");
162			Option = opt_list;
163			break;
164		case 'r':
165			if (Option != opt_unknown)
166				usage("only one operation permitted");
167			Option = opt_delete;
168			break;
169		case 'e':
170			if (Option != opt_unknown)
171				usage("only one operation permitted");
172			Option = opt_edit;
173			break;
174		default:
175			usage("unrecognized option");
176		}
177	}
178
179	endpwent();
180
181	if (Option != opt_unknown) {
182		if (argv[optind] != NULL) {
183			usage("no arguments permitted after this option");
184		}
185	} else {
186		if (argv[optind] != NULL) {
187			Option = opt_replace;
188			(void) strncpy (Filename, argv[optind], (sizeof Filename)-1);
189			Filename[(sizeof Filename)-1] = '\0';
190
191		} else {
192			usage("file name must be specified for replace");
193		}
194	}
195
196	if (Option == opt_replace) {
197		/* we have to open the file here because we're going to
198		 * chdir(2) into /var/cron before we get around to
199		 * reading the file.
200		 */
201		if (!strcmp(Filename, "-")) {
202			NewCrontab = stdin;
203		} else {
204			/* relinquish the setuid status of the binary during
205			 * the open, lest nonroot users read files they should
206			 * not be able to read.  we can't use access() here
207			 * since there's a race condition.  thanks go out to
208			 * Arnt Gulbrandsen <agulbra@pvv.unit.no> for spotting
209			 * the race.
210			 */
211
212			if (swap_uids() < OK)
213				err(ERROR_EXIT, "swapping uids");
214			if (!(NewCrontab = fopen(Filename, "r")))
215				err(ERROR_EXIT, "%s", Filename);
216			if (swap_uids() < OK)
217				err(ERROR_EXIT, "swapping uids back");
218		}
219	}
220
221	Debug(DMISC, ("user=%s, file=%s, option=%s\n",
222		      User, Filename, Options[(int)Option]))
223}
224
225static void
226copy_file(FILE *in, FILE *out) {
227	int	x, ch;
228
229	Set_LineNum(1)
230	/* ignore the top few comments since we probably put them there.
231	 */
232	for (x = 0;  x < NHEADER_LINES;  x++) {
233		ch = get_char(in);
234		if (EOF == ch)
235			break;
236		if ('#' != ch) {
237			putc(ch, out);
238			break;
239		}
240		while (EOF != (ch = get_char(in)))
241			if (ch == '\n')
242				break;
243		if (EOF == ch)
244			break;
245	}
246
247	/* copy the rest of the crontab (if any) to the output file.
248	 */
249	if (EOF != ch)
250		while (EOF != (ch = get_char(in)))
251			putc(ch, out);
252}
253
254static void
255list_cmd() {
256	char	n[MAX_FNAME];
257	FILE	*f;
258
259	log_it(RealUser, Pid, "LIST", User);
260	(void) sprintf(n, CRON_TAB(User));
261	if (!(f = fopen(n, "r"))) {
262		if (errno == ENOENT)
263			errx(ERROR_EXIT, "no crontab for %s", User);
264		else
265			err(ERROR_EXIT, "%s", n);
266	}
267
268	/* file is open. copy to stdout, close.
269	 */
270	copy_file(f, stdout);
271	fclose(f);
272}
273
274
275static void
276delete_cmd() {
277	char	n[MAX_FNAME];
278	int ch, first;
279
280	if (isatty(STDIN_FILENO)) {
281		(void)fprintf(stderr, "remove crontab for %s? ", User);
282		first = ch = getchar();
283		while (ch != '\n' && ch != EOF)
284			ch = getchar();
285		if (first != 'y' && first != 'Y')
286			return;
287	}
288
289	log_it(RealUser, Pid, "DELETE", User);
290	(void) sprintf(n, CRON_TAB(User));
291	if (unlink(n)) {
292		if (errno == ENOENT)
293			errx(ERROR_EXIT, "no crontab for %s", User);
294		else
295			err(ERROR_EXIT, "%s", n);
296	}
297	poke_daemon();
298}
299
300
301static void
302check_error(msg)
303	char	*msg;
304{
305	CheckErrorCount++;
306	fprintf(stderr, "\"%s\":%d: %s\n", Filename, LineNumber-1, msg);
307}
308
309
310static void
311edit_cmd() {
312	char		n[MAX_FNAME], q[MAX_TEMPSTR], *editor;
313	FILE		*f;
314	int		t;
315	struct stat	statbuf, fsbuf;
316	WAIT_T		waiter;
317	PID_T		pid, xpid;
318	mode_t		um;
319	int		syntax_error = 0;
320	char		orig_md5[MD5_SIZE];
321	char		new_md5[MD5_SIZE];
322
323	log_it(RealUser, Pid, "BEGIN EDIT", User);
324	(void) sprintf(n, CRON_TAB(User));
325	if (!(f = fopen(n, "r"))) {
326		if (errno != ENOENT)
327			err(ERROR_EXIT, "%s", n);
328		warnx("no crontab for %s - using an empty one", User);
329		if (!(f = fopen(_PATH_DEVNULL, "r")))
330			err(ERROR_EXIT, _PATH_DEVNULL);
331	}
332
333	um = umask(077);
334	(void) sprintf(Filename, "/tmp/crontab.XXXXXXXXXX");
335	if ((t = mkstemp(Filename)) == -1) {
336		warn("%s", Filename);
337		(void) umask(um);
338		goto fatal;
339	}
340	(void) umask(um);
341#ifdef HAS_FCHOWN
342	if (fchown(t, getuid(), getgid()) < 0) {
343#else
344	if (chown(Filename, getuid(), getgid()) < 0) {
345#endif
346		warn("fchown");
347		goto fatal;
348	}
349	if (!(NewCrontab = fdopen(t, "r+"))) {
350		warn("fdopen");
351		goto fatal;
352	}
353
354	copy_file(f, NewCrontab);
355	fclose(f);
356	if (fflush(NewCrontab))
357		err(ERROR_EXIT, "%s", Filename);
358	if (fstat(t, &fsbuf) < 0) {
359		warn("unable to fstat temp file");
360		goto fatal;
361	}
362 again:
363	if (stat(Filename, &statbuf) < 0) {
364		warn("stat");
365 fatal:		unlink(Filename);
366		exit(ERROR_EXIT);
367	}
368	if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino)
369		errx(ERROR_EXIT, "temp file must be edited in place");
370	if (MD5File(Filename, orig_md5) == NULL) {
371		warn("MD5");
372		goto fatal;
373	}
374
375	if ((!(editor = getenv("VISUAL")))
376	 && (!(editor = getenv("EDITOR")))
377	    ) {
378		editor = EDITOR;
379	}
380
381	/* we still have the file open.  editors will generally rewrite the
382	 * original file rather than renaming/unlinking it and starting a
383	 * new one; even backup files are supposed to be made by copying
384	 * rather than by renaming.  if some editor does not support this,
385	 * then don't use it.  the security problems are more severe if we
386	 * close and reopen the file around the edit.
387	 */
388
389	switch (pid = fork()) {
390	case -1:
391		warn("fork");
392		goto fatal;
393	case 0:
394		/* child */
395		if (setuid(getuid()) < 0)
396			err(ERROR_EXIT, "setuid(getuid())");
397		if (chdir("/tmp") < 0)
398			err(ERROR_EXIT, "chdir(/tmp)");
399		if (strlen(editor) + strlen(Filename) + 2 >= MAX_TEMPSTR)
400			errx(ERROR_EXIT, "editor or filename too long");
401		execlp(editor, editor, Filename, (char *)NULL);
402		err(ERROR_EXIT, "%s", editor);
403		/*NOTREACHED*/
404	default:
405		/* parent */
406		break;
407	}
408
409	/* parent */
410	{
411	void (*f[4])();
412	f[0] = signal(SIGHUP, SIG_IGN);
413	f[1] = signal(SIGINT, SIG_IGN);
414	f[2] = signal(SIGTERM, SIG_IGN);
415	xpid = wait(&waiter);
416	signal(SIGHUP, f[0]);
417	signal(SIGINT, f[1]);
418	signal(SIGTERM, f[2]);
419	}
420	if (xpid != pid) {
421		warnx("wrong PID (%d != %d) from \"%s\"", xpid, pid, editor);
422		goto fatal;
423	}
424	if (WIFEXITED(waiter) && WEXITSTATUS(waiter)) {
425		warnx("\"%s\" exited with status %d", editor, WEXITSTATUS(waiter));
426		goto fatal;
427	}
428	if (WIFSIGNALED(waiter)) {
429		warnx("\"%s\" killed; signal %d (%score dumped)",
430			editor, WTERMSIG(waiter), WCOREDUMP(waiter) ?"" :"no ");
431		goto fatal;
432	}
433	if (stat(Filename, &statbuf) < 0) {
434		warn("stat");
435		goto fatal;
436	}
437	if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino)
438		errx(ERROR_EXIT, "temp file must be edited in place");
439	if (MD5File(Filename, new_md5) == NULL) {
440		warn("MD5");
441		goto fatal;
442	}
443	if (strcmp(orig_md5, new_md5) == 0 && !syntax_error) {
444		warnx("no changes made to crontab");
445		goto remove;
446	}
447	warnx("installing new crontab");
448	switch (replace_cmd()) {
449	case 0:			/* Success */
450		break;
451	case -1:		/* Syntax error */
452		for (;;) {
453			printf("Do you want to retry the same edit? ");
454			fflush(stdout);
455			q[0] = '\0';
456			(void) fgets(q, sizeof q, stdin);
457			switch (islower(q[0]) ? q[0] : tolower(q[0])) {
458			case 'y':
459				syntax_error = 1;
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:		/* Install error */
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 */
487static int
488replace_cmd() {
489	char	n[MAX_FNAME], 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	(void) sprintf(n, "tmp.%d", Pid);
502	(void) 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	fprintf(tmp, "# (Cron version -- %s)\n", rcsid);
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	(void) 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
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		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