xref: /illumos-gate/usr/src/cmd/cron/crontab.c (revision d48be21240dfd051b689384ce2b23479d757f2d8)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
26 /*	  All Rights Reserved	*/
27 
28 /*
29  * Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
30  * Copyright 2022 Sebastian Wiedenroth
31  */
32 
33 #include <sys/types.h>
34 #include <sys/stat.h>
35 #include <sys/types.h>
36 #include <sys/wait.h>
37 #include <errno.h>
38 #include <signal.h>
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <fcntl.h>
43 #include <ctype.h>
44 #include <pwd.h>
45 #include <unistd.h>
46 #include <locale.h>
47 #include <nl_types.h>
48 #include <langinfo.h>
49 #include <libintl.h>
50 #include <security/pam_appl.h>
51 #include <limits.h>
52 #include <libzoneinfo.h>
53 #include "cron.h"
54 #include "getresponse.h"
55 
56 #if defined(XPG4)
57 #define	VIPATH	"/usr/xpg4/bin/vi"
58 #elif defined(XPG6)
59 #define	VIPATH	"/usr/xpg6/bin/vi"
60 #else
61 #define	_XPG_NOTDEFINED
62 #define	VIPATH	"vi"
63 #endif
64 
65 #define	TMPFILE		"_cron"		/* prefix for tmp file */
66 #define	CRMODE		0600	/* mode for creating crontabs */
67 
68 #define	BADCREATE	\
69 	"can't create your crontab file in the crontab directory."
70 #define	BADOPEN		"can't open your crontab file."
71 #define	BADSHELL	\
72 	"because your login shell isn't /usr/bin/sh, you can't use cron."
73 #define	WARNSHELL	"warning: commands will be executed using /usr/bin/sh\n"
74 #define	BADUSAGE	\
75 	"usage:\n"			\
76 	"\tcrontab [-u username] [file]\n"		\
77 	"\tcrontab [-u username] { -e | -l | -r }\n"	\
78 	"\tcrontab { -e | -l | -r } [username]"
79 #define	INVALIDUSER	"you are not a valid user (no entry in /etc/passwd)."
80 #define	NOTALLOWED	"you are not authorized to use cron.  Sorry."
81 #define	NOTROOT		\
82 	"you must be super-user to access another user's crontab file"
83 #define	AUDITREJECT	"The audit context for your shell has not been set."
84 #define	EOLN		"unexpected end of line."
85 #define	UNEXPECT	"unexpected character found in line."
86 #define	OUTOFBOUND	"number out of bounds."
87 #define	OVERFLOW	"too many elements."
88 #define	ERRSFND		"errors detected in input, no crontab file generated."
89 #define	ED_ERROR	\
90 	"     The editor indicates that an error occurred while you were\n"\
91 	"     editing the crontab data - usually a minor typing error.\n\n"
92 #define	BADREAD		"error reading your crontab file"
93 #define	ED_PROMPT	\
94 	"     Edit again, to ensure crontab information is intact (%s/%s)?\n"\
95 	"     ('%s' will discard edits.)"
96 #define	NAMETOOLONG	"login name too long"
97 #define	BAD_TZ	"Timezone unrecognized in: %s"
98 #define	BAD_SHELL	"Invalid shell specified: %s"
99 #define	BAD_HOME	"Unable to access directory: %s\t%s\n"
100 #define	BAD_RAND_DELAY	"Invalid delay: %s"
101 
102 extern int	per_errno;
103 
104 extern int	audit_crontab_modify(char *, char *, int);
105 extern int	audit_crontab_delete(char *, int);
106 extern int	audit_crontab_not_allowed(uid_t, char *);
107 
108 static int	err;
109 int		cursor;
110 char		*cf;
111 char		*tnam;
112 char		edtemp[5+13+1];
113 char		line[CTLINESIZE];
114 static		char	login[UNAMESIZE];
115 
116 static void	catch(int);
117 static void	crabort(char *);
118 static void	cerror(char *);
119 static void	copycron(FILE *);
120 
121 int
122 main(int argc, char **argv)
123 {
124 	int	c, r;
125 	int	rflag	= 0;
126 	int	lflag	= 0;
127 	int	eflag	= 0;
128 	int	errflg	= 0;
129 	char *pp;
130 	FILE *fp, *tmpfp;
131 	struct stat stbuf;
132 	struct passwd *pwp;
133 	time_t omodtime;
134 	char *editor;
135 	uid_t ruid;
136 	pid_t pid;
137 	int stat_loc;
138 	int ret;
139 	char real_login[UNAMESIZE];
140 	char *user = NULL;
141 	int tmpfd = -1;
142 	pam_handle_t *pamh;
143 	int pam_error;
144 	char *buf;
145 	size_t buflen;
146 
147 	(void) setlocale(LC_ALL, "");
148 #if !defined(TEXT_DOMAIN)	/* Should be defined by cc -D */
149 #define	TEXT_DOMAIN "SYS_TEST"	/* Use this only if it wasn't */
150 #endif
151 	(void) textdomain(TEXT_DOMAIN);
152 
153 	if (init_yes() < 0) {
154 		(void) fprintf(stderr, gettext(ERR_MSG_INIT_YES),
155 		    strerror(errno));
156 		exit(1);
157 	}
158 
159 	while ((c = getopt(argc, argv, "elru:")) != EOF) {
160 		switch (c) {
161 			case 'e':
162 				eflag++;
163 				break;
164 			case 'l':
165 				lflag++;
166 				break;
167 			case 'r':
168 				rflag++;
169 				break;
170 			case 'u':
171 				user = optarg;
172 				break;
173 			case '?':
174 				errflg++;
175 				break;
176 		}
177 	}
178 
179 	argc -= optind;
180 	argv += optind;
181 
182 	if (eflag + lflag + rflag > 1)
183 		errflg++;
184 
185 	if ((eflag || lflag || rflag) && argc > 0) {
186 		if (user != NULL)
187 			errflg++;
188 		else
189 			user = *argv;
190 	}
191 
192 	if (errflg || argc > 1)
193 		crabort(BADUSAGE);
194 
195 	ruid = getuid();
196 	if ((pwp = getpwuid(ruid)) == NULL)
197 		crabort(INVALIDUSER);
198 
199 	if (strlcpy(real_login, pwp->pw_name, sizeof (real_login))
200 	    >= sizeof (real_login)) {
201 		crabort(NAMETOOLONG);
202 	}
203 
204 	if (user != NULL) {
205 		if ((pwp = getpwnam(user)) == NULL)
206 			crabort(INVALIDUSER);
207 
208 		if (!cron_admin(real_login)) {
209 			if (pwp->pw_uid != ruid)
210 				crabort(NOTROOT);
211 			else
212 				pp = getuser(ruid);
213 		} else {
214 			pp = user;
215 		}
216 	} else {
217 		pp = getuser(ruid);
218 	}
219 
220 	if (pp == NULL) {
221 		if (per_errno == 2)
222 			crabort(BADSHELL);
223 		else
224 			crabort(INVALIDUSER);
225 	}
226 	if (strlcpy(login, pp, sizeof (login)) >= sizeof (login))
227 		crabort(NAMETOOLONG);
228 	if (!allowed(login, CRONALLOW, CRONDENY))
229 		crabort(NOTALLOWED);
230 
231 	/* Do account validation check */
232 	pam_error = pam_start("cron", pp, NULL, &pamh);
233 	if (pam_error != PAM_SUCCESS) {
234 		crabort((char *)pam_strerror(pamh, pam_error));
235 	}
236 	pam_error = pam_acct_mgmt(pamh, PAM_SILENT);
237 	if (pam_error != PAM_SUCCESS) {
238 		(void) fprintf(stderr, gettext("Warning - Invalid account: "
239 		    "'%s' not allowed to execute cronjobs\n"), pp);
240 	}
241 	(void) pam_end(pamh, PAM_SUCCESS);
242 
243 
244 	/* check for unaudited shell */
245 	if (audit_crontab_not_allowed(ruid, pp))
246 		crabort(AUDITREJECT);
247 
248 	cf = xmalloc(strlen(CRONDIR)+strlen(login)+2);
249 	strcat(strcat(strcpy(cf, CRONDIR), "/"), login);
250 
251 	if (rflag) {
252 		r = unlink(cf);
253 		cron_sendmsg(DELETE, login, login, CRON);
254 		audit_crontab_delete(cf, r);
255 		exit(0);
256 	}
257 	if (lflag) {
258 		if ((fp = fopen(cf, "r")) == NULL)
259 			crabort(BADOPEN);
260 		while (fgets(line, CTLINESIZE, fp) != NULL)
261 			fputs(line, stdout);
262 		fclose(fp);
263 		exit(0);
264 	}
265 	if (eflag) {
266 		if ((fp = fopen(cf, "r")) == NULL) {
267 			if (errno != ENOENT)
268 				crabort(BADOPEN);
269 		}
270 		(void) strcpy(edtemp, "/tmp/crontabXXXXXX");
271 		tmpfd = mkstemp(edtemp);
272 		if (fchown(tmpfd, ruid, -1) == -1) {
273 			(void) close(tmpfd);
274 			crabort("fchown of temporary file failed");
275 		}
276 		(void) close(tmpfd);
277 		/*
278 		 * Fork off a child with user's permissions,
279 		 * to edit the crontab file
280 		 */
281 		if ((pid = fork()) == (pid_t)-1)
282 			crabort("fork failed");
283 		if (pid == 0) {		/* child process */
284 			/* give up super-user privileges. */
285 			setuid(ruid);
286 			if ((tmpfp = fopen(edtemp, "w")) == NULL)
287 				crabort("can't create temporary file");
288 			if (fp != NULL) {
289 				/*
290 				 * Copy user's crontab file to temporary file.
291 				 */
292 				while (fgets(line, CTLINESIZE, fp) != NULL) {
293 					fputs(line, tmpfp);
294 					if (ferror(tmpfp)) {
295 						fclose(fp);
296 						fclose(tmpfp);
297 						crabort("write error on"
298 						    "temporary file");
299 					}
300 				}
301 				if (ferror(fp)) {
302 					fclose(fp);
303 					fclose(tmpfp);
304 					crabort(BADREAD);
305 				}
306 				fclose(fp);
307 			}
308 			if (fclose(tmpfp) == EOF)
309 				crabort("write error on temporary file");
310 			if (stat(edtemp, &stbuf) < 0)
311 				crabort("can't stat temporary file");
312 			omodtime = stbuf.st_mtime;
313 #ifdef _XPG_NOTDEFINED
314 			editor = getenv("VISUAL");
315 			if (editor == NULL) {
316 #endif
317 				editor = getenv("EDITOR");
318 				if (editor == NULL)
319 					editor = VIPATH;
320 #ifdef _XPG_NOTDEFINED
321 			}
322 #endif
323 			buflen = strlen(editor) + strlen(edtemp) + 2;
324 			buf = xmalloc(buflen);
325 			(void) snprintf(buf, buflen, "%s %s", editor, edtemp);
326 
327 			sleep(1);
328 
329 			while (1) {
330 				ret = system(buf);
331 
332 				/* sanity checks */
333 				if ((tmpfp = fopen(edtemp, "r")) == NULL)
334 					crabort("can't open temporary file");
335 				if (fstat(fileno(tmpfp), &stbuf) < 0)
336 					crabort("can't stat temporary file");
337 				if (stbuf.st_size == 0)
338 					crabort("temporary file empty");
339 				if (omodtime == stbuf.st_mtime) {
340 					(void) unlink(edtemp);
341 					fprintf(stderr, gettext(
342 					    "The crontab file was not"
343 					    " changed.\n"));
344 					exit(1);
345 				}
346 				if ((ret) && (errno != EINTR)) {
347 					/*
348 					 * Some editors (like 'vi') can return
349 					 * a non-zero exit status even though
350 					 * everything is okay. Need to check.
351 					 */
352 					fprintf(stderr, gettext(ED_ERROR));
353 					fflush(stderr);
354 					if (isatty(fileno(stdin))) {
355 						/* Interactive */
356 						fprintf(stdout,
357 						    gettext(ED_PROMPT),
358 						    yesstr, nostr, nostr);
359 						fflush(stdout);
360 
361 						if (yes()) {
362 							/* Edit again */
363 							continue;
364 						} else {
365 							/* Dump changes */
366 							(void) unlink(edtemp);
367 							exit(1);
368 						}
369 					} else {
370 						/*
371 						 * Non-interactive, dump changes
372 						 */
373 						(void) unlink(edtemp);
374 						exit(1);
375 					}
376 				}
377 				exit(0);
378 			} /* while (1) */
379 		}
380 
381 		/* fix for 1125555 - ignore common signals while waiting */
382 		(void) signal(SIGINT, SIG_IGN);
383 		(void) signal(SIGHUP, SIG_IGN);
384 		(void) signal(SIGQUIT, SIG_IGN);
385 		(void) signal(SIGTERM, SIG_IGN);
386 		wait(&stat_loc);
387 		if ((stat_loc & 0xFF00) != 0)
388 			exit(1);
389 
390 		/*
391 		 * unlink edtemp as 'ruid'. The file contents will be held
392 		 * since we open the file descriptor 'tmpfp' before calling
393 		 * unlink.
394 		 */
395 		if (((ret = seteuid(ruid)) < 0) ||
396 		    ((tmpfp = fopen(edtemp, "r")) == NULL) ||
397 		    (unlink(edtemp) == -1)) {
398 			fprintf(stderr, "crontab: %s: %s\n",
399 			    edtemp, errmsg(errno));
400 			if ((ret < 0) || (tmpfp == NULL))
401 				(void) unlink(edtemp);
402 			exit(1);
403 		} else
404 			seteuid(0);
405 
406 		copycron(tmpfp);
407 	} else {
408 		if (argc == 0)
409 			copycron(stdin);
410 		else if (seteuid(getuid()) != 0 || (fp = fopen(argv[0], "r"))
411 		    == NULL)
412 			crabort(BADOPEN);
413 		else {
414 			seteuid(0);
415 			copycron(fp);
416 		}
417 	}
418 	cron_sendmsg(ADD, login, login, CRON);
419 /*
420  *	if (per_errno == 2)
421  *		fprintf(stderr, gettext(WARNSHELL));
422  */
423 	return (0);
424 }
425 
426 static void
427 copycron(FILE *fp)
428 {
429 	FILE *tfp;
430 	char pid[6], *tnam_end;
431 	int t;
432 	char buf[LINE_MAX];
433 	const char *errstr;
434 	cferror_t cferr;
435 
436 	sprintf(pid, "%-5d", getpid());
437 	tnam = xmalloc(strlen(CRONDIR)+strlen(TMPFILE)+7);
438 	strcat(strcat(strcat(strcpy(tnam, CRONDIR), "/"), TMPFILE), pid);
439 	/* cut trailing blanks */
440 	tnam_end = strchr(tnam, ' ');
441 	if (tnam_end != NULL)
442 		*tnam_end = 0;
443 	/* catch SIGINT, SIGHUP, SIGQUIT signals */
444 	if (signal(SIGINT, catch) == SIG_IGN)
445 		signal(SIGINT, SIG_IGN);
446 	if (signal(SIGHUP, catch) == SIG_IGN) signal(SIGHUP, SIG_IGN);
447 	if (signal(SIGQUIT, catch) == SIG_IGN) signal(SIGQUIT, SIG_IGN);
448 	if (signal(SIGTERM, catch) == SIG_IGN) signal(SIGTERM, SIG_IGN);
449 	if ((t = creat(tnam, CRMODE)) == -1) crabort(BADCREATE);
450 	if ((tfp = fdopen(t, "w")) == NULL) {
451 		unlink(tnam);
452 		crabort(BADCREATE);
453 	}
454 	err = 0;	/* if errors found, err set to 1 */
455 	while (fgets(line, CTLINESIZE, fp) != NULL) {
456 		cursor = 0;
457 		while (line[cursor] == ' ' || line[cursor] == '\t')
458 			cursor++;
459 		/* fix for 1039689 - treat blank line like a comment */
460 		if (line[cursor] == '#' || line[cursor] == '\n')
461 			goto cont;
462 
463 		if (strncmp(&line[cursor], ENV_TZ, strlen(ENV_TZ)) == 0) {
464 			char *x;
465 
466 			(void) strncpy(buf, &line[cursor + strlen(ENV_TZ)],
467 			    sizeof (buf));
468 			if ((x = strchr(buf, '\n')) != NULL)
469 				*x = '\0';
470 
471 			if (isvalid_tz(buf, NULL, _VTZ_ALL)) {
472 				goto cont;
473 			} else {
474 				err = 1;
475 				fprintf(stderr, BAD_TZ, &line[cursor]);
476 				continue;
477 			}
478 		} else if (strncmp(&line[cursor], ENV_SHELL,
479 		    strlen(ENV_SHELL)) == 0) {
480 			char *x;
481 
482 			(void) strncpy(buf, &line[cursor + strlen(ENV_SHELL)],
483 			    sizeof (buf));
484 			if ((x = strchr(buf, '\n')) != NULL)
485 				*x = '\0';
486 
487 			if (isvalid_shell(buf)) {
488 				goto cont;
489 			} else {
490 				err = 1;
491 				fprintf(stderr, BAD_SHELL, &line[cursor]);
492 				continue;
493 			}
494 		} else if (strncmp(&line[cursor], ENV_HOME,
495 		    strlen(ENV_HOME)) == 0) {
496 			char *x;
497 
498 			(void) strncpy(buf, &line[cursor + strlen(ENV_HOME)],
499 			    sizeof (buf));
500 			if ((x = strchr(buf, '\n')) != NULL)
501 				*x = '\0';
502 			if (chdir(buf) == 0) {
503 				goto cont;
504 			} else {
505 				err = 1;
506 				fprintf(stderr, BAD_HOME, &line[cursor],
507 				    strerror(errno));
508 				continue;
509 			}
510 		} else if (strncmp(&line[cursor], ENV_RANDOM_DELAY,
511 		    strlen(ENV_RANDOM_DELAY)) == 0) {
512 			char *x;
513 
514 			(void) strncpy(buf,
515 			    &line[cursor + strlen(ENV_RANDOM_DELAY)],
516 			    sizeof (buf));
517 			if ((x = strchr(buf, '\n')) != NULL)
518 				*x = '\0';
519 
520 			(void) strtonum(buf, 0, UINT32_MAX / 60, &errstr);
521 			if (errstr == NULL) {
522 				goto cont;
523 			} else {
524 				err = 1;
525 				fprintf(stderr, BAD_RAND_DELAY,
526 				    &line[cursor], strerror(errno));
527 				continue;
528 			}
529 		}
530 
531 		if ((cferr = next_field(0, 59, line, &cursor, NULL)) != CFOK ||
532 		    (cferr = next_field(0, 23, line, &cursor, NULL)) != CFOK ||
533 		    (cferr = next_field(1, 31, line, &cursor, NULL)) != CFOK ||
534 		    (cferr = next_field(1, 12, line, &cursor, NULL)) != CFOK ||
535 		    (cferr = next_field(0, 6, line, &cursor, NULL)) != CFOK) {
536 			switch (cferr) {
537 			case CFEOLN:
538 				cerror(EOLN);
539 				break;
540 			case CFUNEXPECT:
541 				cerror(UNEXPECT);
542 				break;
543 			case CFOUTOFBOUND:
544 				cerror(OUTOFBOUND);
545 				break;
546 			case CFEOVERFLOW:
547 				cerror(OVERFLOW);
548 				break;
549 			case CFENOMEM:
550 				(void) fprintf(stderr, "Out of memory\n");
551 				exit(55);
552 				break;
553 			default:
554 				break;
555 			}
556 			continue;
557 		}
558 
559 		if (line[++cursor] == '\0') {
560 			cerror(EOLN);
561 			continue;
562 		}
563 cont:
564 		if (fputs(line, tfp) == EOF) {
565 			unlink(tnam);
566 			crabort(BADCREATE);
567 		}
568 	}
569 	fclose(fp);
570 	fclose(tfp);
571 
572 	/* audit differences between old and new crontabs */
573 	audit_crontab_modify(cf, tnam, err);
574 
575 	if (!err) {
576 		/* make file tfp the new crontab */
577 		unlink(cf);
578 		if (link(tnam, cf) == -1) {
579 			unlink(tnam);
580 			crabort(BADCREATE);
581 		}
582 	} else {
583 		crabort(ERRSFND);
584 	}
585 	unlink(tnam);
586 }
587 
588 static void
589 cerror(char *msg)
590 {
591 	fprintf(stderr, gettext("%scrontab: error on previous line; %s\n"),
592 	    line, msg);
593 	err = 1;
594 }
595 
596 
597 static void
598 catch(int x)
599 {
600 	unlink(tnam);
601 	exit(1);
602 }
603 
604 static void
605 crabort(char *msg)
606 {
607 	int sverrno;
608 
609 	if (strcmp(edtemp, "") != 0) {
610 		sverrno = errno;
611 		(void) unlink(edtemp);
612 		errno = sverrno;
613 	}
614 	if (tnam != NULL) {
615 		sverrno = errno;
616 		(void) unlink(tnam);
617 		errno = sverrno;
618 	}
619 	fprintf(stderr, "crontab: %s\n", gettext(msg));
620 	exit(1);
621 }
622