crontab.c revision 184809 
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 184809 2008-11-10 06:35:30Z matteo $";
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(void),
67			delete_cmd(void),
68			edit_cmd(void),
69			poke_daemon(void),
70			check_error(char *),
71			parse_args(int c, char *v[]);
72static	int		replace_cmd(void);
73
74
75static void
76usage(char *msg)
77{
78	fprintf(stderr, "crontab: usage error: %s\n", msg);
79	fprintf(stderr, "%s\n%s\n",
80		"usage: crontab [-u user] file",
81		"       crontab [-u user] { -e | -l | -r }");
82	exit(ERROR_EXIT);
83}
84
85
86int
87main(int argc, char *argv[])
88{
89	int	exitstatus;
90
91	Pid = getpid();
92	ProgramName = argv[0];
93
94#if defined(POSIX)
95	setlocale(LC_ALL, "");
96#endif
97
98#if defined(BSD)
99	setlinebuf(stderr);
100#endif
101	parse_args(argc, argv);		/* sets many globals, opens a file */
102	set_cron_uid();
103	set_cron_cwd();
104	if (!allowed(User)) {
105		warnx("you (%s) are not allowed to use this program", User);
106		log_it(RealUser, Pid, "AUTH", "crontab command not allowed");
107		exit(ERROR_EXIT);
108	}
109	exitstatus = OK_EXIT;
110	switch (Option) {
111	case opt_list:		list_cmd();
112				break;
113	case opt_delete:	delete_cmd();
114				break;
115	case opt_edit:		edit_cmd();
116				break;
117	case opt_replace:	if (replace_cmd() < 0)
118					exitstatus = ERROR_EXIT;
119				break;
120	case opt_unknown:
121				break;
122	}
123	exit(exitstatus);
124	/*NOTREACHED*/
125}
126
127
128static void
129parse_args(argc, argv)
130	int	argc;
131	char	*argv[];
132{
133	int		argch;
134	char		resolved_path[PATH_MAX];
135
136	if (!(pw = getpwuid(getuid())))
137		errx(ERROR_EXIT, "your UID isn't in the passwd file, bailing out");
138	bzero(pw->pw_passwd, strlen(pw->pw_passwd));
139	(void) strncpy(User, pw->pw_name, (sizeof User)-1);
140	User[(sizeof User)-1] = '\0';
141	strcpy(RealUser, User);
142	Filename[0] = '\0';
143	Option = opt_unknown;
144	while ((argch = getopt(argc, argv, "u:lerx:")) != -1) {
145		switch (argch) {
146		case 'x':
147			if (!set_debug_flags(optarg))
148				usage("bad debug option");
149			break;
150		case 'u':
151			if (getuid() != ROOT_UID)
152				errx(ERROR_EXIT, "must be privileged to use -u");
153			if (!(pw = getpwnam(optarg)))
154				errx(ERROR_EXIT, "user `%s' unknown", optarg);
155			bzero(pw->pw_passwd, strlen(pw->pw_passwd));
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 if (realpath(Filename, resolved_path) != NULL &&
204		    !strcmp(resolved_path, SYSCRONTAB)) {
205			err(ERROR_EXIT, SYSCRONTAB " must be edited manually");
206		} else {
207			/* relinquish the setuid status of the binary during
208			 * the open, lest nonroot users read files they should
209			 * not be able to read.  we can't use access() here
210			 * since there's a race condition.  thanks go out to
211			 * Arnt Gulbrandsen <agulbra@pvv.unit.no> for spotting
212			 * the race.
213			 */
214
215			if (swap_uids() < OK)
216				err(ERROR_EXIT, "swapping uids");
217			if (!(NewCrontab = fopen(Filename, "r")))
218				err(ERROR_EXIT, "%s", Filename);
219			if (swap_uids_back() < OK)
220				err(ERROR_EXIT, "swapping uids back");
221		}
222	}
223
224	Debug(DMISC, ("user=%s, file=%s, option=%s\n",
225		      User, Filename, Options[(int)Option]))
226}
227
228static void
229copy_file(FILE *in, FILE *out) {
230	int	x, ch;
231
232	Set_LineNum(1)
233	/* ignore the top few comments since we probably put them there.
234	 */
235	for (x = 0;  x < NHEADER_LINES;  x++) {
236		ch = get_char(in);
237		if (EOF == ch)
238			break;
239		if ('#' != ch) {
240			putc(ch, out);
241			break;
242		}
243		while (EOF != (ch = get_char(in)))
244			if (ch == '\n')
245				break;
246		if (EOF == ch)
247			break;
248	}
249
250	/* copy the rest of the crontab (if any) to the output file.
251	 */
252	if (EOF != ch)
253		while (EOF != (ch = get_char(in)))
254			putc(ch, out);
255}
256
257static void
258list_cmd() {
259	char	n[MAX_FNAME];
260	FILE	*f;
261
262	log_it(RealUser, Pid, "LIST", User);
263	(void) snprintf(n, sizeof(n), CRON_TAB(User));
264	if (!(f = fopen(n, "r"))) {
265		if (errno == ENOENT)
266			errx(ERROR_EXIT, "no crontab for %s", User);
267		else
268			err(ERROR_EXIT, "%s", n);
269	}
270
271	/* file is open. copy to stdout, close.
272	 */
273	copy_file(f, stdout);
274	fclose(f);
275}
276
277
278static void
279delete_cmd() {
280	char	n[MAX_FNAME];
281	int ch, first;
282
283	if (isatty(STDIN_FILENO)) {
284		(void)fprintf(stderr, "remove crontab for %s? ", User);
285		first = ch = getchar();
286		while (ch != '\n' && ch != EOF)
287			ch = getchar();
288		if (first != 'y' && first != 'Y')
289			return;
290	}
291
292	log_it(RealUser, Pid, "DELETE", User);
293	(void) snprintf(n, sizeof(n), CRON_TAB(User));
294	if (unlink(n)) {
295		if (errno == ENOENT)
296			errx(ERROR_EXIT, "no crontab for %s", User);
297		else
298			err(ERROR_EXIT, "%s", n);
299	}
300	poke_daemon();
301}
302
303
304static void
305check_error(msg)
306	char	*msg;
307{
308	CheckErrorCount++;
309	fprintf(stderr, "\"%s\":%d: %s\n", Filename, LineNumber-1, msg);
310}
311
312
313static void
314edit_cmd() {
315	char		n[MAX_FNAME], q[MAX_TEMPSTR], *editor;
316	FILE		*f;
317	int		t;
318	struct stat	statbuf, fsbuf;
319	WAIT_T		waiter;
320	PID_T		pid, xpid;
321	mode_t		um;
322	int		syntax_error = 0;
323	char		orig_md5[MD5_SIZE];
324	char		new_md5[MD5_SIZE];
325
326	log_it(RealUser, Pid, "BEGIN EDIT", User);
327	(void) snprintf(n, sizeof(n), CRON_TAB(User));
328	if (!(f = fopen(n, "r"))) {
329		if (errno != ENOENT)
330			err(ERROR_EXIT, "%s", n);
331		warnx("no crontab for %s - using an empty one", User);
332		if (!(f = fopen(_PATH_DEVNULL, "r")))
333			err(ERROR_EXIT, _PATH_DEVNULL);
334	}
335
336	um = umask(077);
337	(void) snprintf(Filename, sizeof(Filename), "/tmp/crontab.XXXXXXXXXX");
338	if ((t = mkstemp(Filename)) == -1) {
339		warn("%s", Filename);
340		(void) umask(um);
341		goto fatal;
342	}
343	(void) umask(um);
344#ifdef HAS_FCHOWN
345	if (fchown(t, getuid(), getgid()) < 0) {
346#else
347	if (chown(Filename, getuid(), getgid()) < 0) {
348#endif
349		warn("fchown");
350		goto fatal;
351	}
352	if (!(NewCrontab = fdopen(t, "r+"))) {
353		warn("fdopen");
354		goto fatal;
355	}
356
357	copy_file(f, NewCrontab);
358	fclose(f);
359	if (fflush(NewCrontab))
360		err(ERROR_EXIT, "%s", Filename);
361	if (fstat(t, &fsbuf) < 0) {
362		warn("unable to fstat temp file");
363		goto fatal;
364	}
365 again:
366	if (stat(Filename, &statbuf) < 0) {
367		warn("stat");
368 fatal:		unlink(Filename);
369		exit(ERROR_EXIT);
370	}
371	if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino)
372		errx(ERROR_EXIT, "temp file must be edited in place");
373	if (MD5File(Filename, orig_md5) == NULL) {
374		warn("MD5");
375		goto fatal;
376	}
377
378	if ((!(editor = getenv("VISUAL")))
379	 && (!(editor = getenv("EDITOR")))
380	    ) {
381		editor = EDITOR;
382	}
383
384	/* we still have the file open.  editors will generally rewrite the
385	 * original file rather than renaming/unlinking it and starting a
386	 * new one; even backup files are supposed to be made by copying
387	 * rather than by renaming.  if some editor does not support this,
388	 * then don't use it.  the security problems are more severe if we
389	 * close and reopen the file around the edit.
390	 */
391
392	switch (pid = fork()) {
393	case -1:
394		warn("fork");
395		goto fatal;
396	case 0:
397		/* child */
398		if (setuid(getuid()) < 0)
399			err(ERROR_EXIT, "setuid(getuid())");
400		if (chdir("/tmp") < 0)
401			err(ERROR_EXIT, "chdir(/tmp)");
402		if (strlen(editor) + strlen(Filename) + 2 >= MAX_TEMPSTR)
403			errx(ERROR_EXIT, "editor or filename too long");
404		execlp(editor, editor, Filename, (char *)NULL);
405		err(ERROR_EXIT, "%s", editor);
406		/*NOTREACHED*/
407	default:
408		/* parent */
409		break;
410	}
411
412	/* parent */
413	{
414	void (*sig[3])(int signal);
415	sig[0] = signal(SIGHUP, SIG_IGN);
416	sig[1] = signal(SIGINT, SIG_IGN);
417	sig[2] = signal(SIGTERM, SIG_IGN);
418	xpid = wait(&waiter);
419	signal(SIGHUP, sig[0]);
420	signal(SIGINT, sig[1]);
421	signal(SIGTERM, sig[2]);
422	}
423	if (xpid != pid) {
424		warnx("wrong PID (%d != %d) from \"%s\"", xpid, pid, editor);
425		goto fatal;
426	}
427	if (WIFEXITED(waiter) && WEXITSTATUS(waiter)) {
428		warnx("\"%s\" exited with status %d", editor, WEXITSTATUS(waiter));
429		goto fatal;
430	}
431	if (WIFSIGNALED(waiter)) {
432		warnx("\"%s\" killed; signal %d (%score dumped)",
433			editor, WTERMSIG(waiter), WCOREDUMP(waiter) ?"" :"no ");
434		goto fatal;
435	}
436	if (stat(Filename, &statbuf) < 0) {
437		warn("stat");
438		goto fatal;
439	}
440	if (statbuf.st_dev != fsbuf.st_dev || statbuf.st_ino != fsbuf.st_ino)
441		errx(ERROR_EXIT, "temp file must be edited in place");
442	if (MD5File(Filename, new_md5) == NULL) {
443		warn("MD5");
444		goto fatal;
445	}
446	if (strcmp(orig_md5, new_md5) == 0 && !syntax_error) {
447		warnx("no changes made to crontab");
448		goto remove;
449	}
450	warnx("installing new crontab");
451	switch (replace_cmd()) {
452	case 0:			/* Success */
453		break;
454	case -1:		/* Syntax error */
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				syntax_error = 1;
463				goto again;
464			case 'n':
465				goto abandon;
466			default:
467				fprintf(stderr, "Enter Y or N\n");
468			}
469		}
470		/*NOTREACHED*/
471	case -2:		/* Install error */
472	abandon:
473		warnx("edits left in %s", Filename);
474		goto done;
475	default:
476		warnx("panic: bad switch() in replace_cmd()");
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	if (envp == NULL) {
500		warnx("cannot allocate memory");
501		return (-2);
502	}
503
504	(void) snprintf(n, sizeof(n), "tmp.%d", Pid);
505	(void) snprintf(tn, sizeof(n), CRON_TAB(n));
506
507	if (!(tmp = fopen(tn, "w+"))) {
508		warn("%s", tn);
509		return (-2);
510	}
511
512	/* write a signature at the top of the file.
513	 *
514	 * VERY IMPORTANT: make sure NHEADER_LINES agrees with this code.
515	 */
516	fprintf(tmp, "# DO NOT EDIT THIS FILE - edit the master and reinstall.\n");
517	fprintf(tmp, "# (%s installed on %-24.24s)\n", Filename, ctime(&now));
518	fprintf(tmp, "# (Cron version -- %s)\n", rcsid);
519
520	/* copy the crontab to the tmp
521	 */
522	rewind(NewCrontab);
523	Set_LineNum(1)
524	while (EOF != (ch = get_char(NewCrontab)))
525		putc(ch, tmp);
526	ftruncate(fileno(tmp), ftell(tmp));
527	fflush(tmp);  rewind(tmp);
528
529	if (ferror(tmp)) {
530		warnx("error while writing new crontab to %s", tn);
531		fclose(tmp);  unlink(tn);
532		return (-2);
533	}
534
535	/* check the syntax of the file being installed.
536	 */
537
538	/* BUG: was reporting errors after the EOF if there were any errors
539	 * in the file proper -- kludged it by stopping after first error.
540	 *		vix 31mar87
541	 */
542	Set_LineNum(1 - NHEADER_LINES)
543	CheckErrorCount = 0;  eof = FALSE;
544	while (!CheckErrorCount && !eof) {
545		switch (load_env(envstr, tmp)) {
546		case ERR:
547			eof = TRUE;
548			break;
549		case FALSE:
550			e = load_entry(tmp, check_error, pw, envp);
551			if (e)
552				free(e);
553			break;
554		case TRUE:
555			break;
556		}
557	}
558
559	if (CheckErrorCount != 0) {
560		warnx("errors in crontab file, can't install");
561		fclose(tmp);  unlink(tn);
562		return (-1);
563	}
564
565#ifdef HAS_FCHOWN
566	if (fchown(fileno(tmp), ROOT_UID, -1) < OK)
567#else
568	if (chown(tn, ROOT_UID, -1) < OK)
569#endif
570	{
571		warn("chown");
572		fclose(tmp);  unlink(tn);
573		return (-2);
574	}
575
576#ifdef HAS_FCHMOD
577	if (fchmod(fileno(tmp), 0600) < OK)
578#else
579	if (chmod(tn, 0600) < OK)
580#endif
581	{
582		warn("chown");
583		fclose(tmp);  unlink(tn);
584		return (-2);
585	}
586
587	if (fclose(tmp) == EOF) {
588		warn("fclose");
589		unlink(tn);
590		return (-2);
591	}
592
593	(void) snprintf(n, sizeof(n), CRON_TAB(User));
594	if (rename(tn, n)) {
595		warn("error renaming %s to %s", tn, n);
596		unlink(tn);
597		return (-2);
598	}
599
600	log_it(RealUser, Pid, "REPLACE", User);
601
602	poke_daemon();
603
604	return (0);
605}
606
607
608static void
609poke_daemon() {
610#ifdef USE_UTIMES
611	struct timeval tvs[2];
612	struct timezone tz;
613
614	(void) gettimeofday(&tvs[0], &tz);
615	tvs[1] = tvs[0];
616	if (utimes(SPOOL_DIR, tvs) < OK) {
617		warn("can't update mtime on spooldir %s", SPOOL_DIR);
618		return;
619	}
620#else
621	if (utime(SPOOL_DIR, NULL) < OK) {
622		warn("can't update mtime on spooldir %s", SPOOL_DIR);
623		return;
624	}
625#endif /*USE_UTIMES*/
626}
627