1/*	$OpenBSD: entry.c,v 1.59 2023/07/19 21:26:02 millert Exp $	*/
2
3/*
4 * Copyright 1988,1990,1993,1994 by Paul Vixie
5 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
6 * Copyright (c) 1997,2000 by Internet Software Consortium, Inc.
7 *
8 * Permission to use, copy, modify, and distribute this software for any
9 * purpose with or without fee is hereby granted, provided that the above
10 * copyright notice and this permission notice appear in all copies.
11 *
12 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
13 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
14 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
15 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
16 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
17 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
18 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
19 */
20
21#include <sys/types.h>
22
23#include <bitstring.h>		/* for structs.h */
24#include <ctype.h>
25#include <pwd.h>
26#include <stdio.h>
27#include <stdlib.h>
28#include <string.h>
29#include <syslog.h>
30#include <time.h>		/* for structs.h */
31#include <unistd.h>
32
33#include "pathnames.h"
34#include "macros.h"
35#include "structs.h"
36#include "funcs.h"
37
38typedef	enum ecode {
39	e_none, e_minute, e_hour, e_dom, e_month, e_dow,
40	e_cmd, e_timespec, e_username, e_option, e_memory, e_flags
41} ecode_e;
42
43static const char *ecodes[] = {
44	"no error",
45	"bad minute",
46	"bad hour",
47	"bad day-of-month",
48	"bad month",
49	"bad day-of-week",
50	"bad command",
51	"bad time specifier",
52	"bad username",
53	"bad option",
54	"out of memory",
55	"bad flags"
56};
57
58static const char *MonthNames[] = {
59	"Jan", "Feb", "Mar", "Apr", "May", "Jun",
60	"Jul", "Aug", "Sep", "Oct", "Nov", "Dec",
61	NULL
62};
63
64static const char *DowNames[] = {
65	"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun",
66	NULL
67};
68
69static int	get_list(bitstr_t *, int, int, const char *[], int, FILE *),
70		get_range(bitstr_t *, int, int, const char *[], int, FILE *),
71		get_number(int *, int, const char *[], int, FILE *, const char *),
72		set_element(bitstr_t *, int, int, int),
73		set_range(bitstr_t *, int, int, int, int, int);
74
75void
76free_entry(entry *e)
77{
78	free(e->cmd);
79	free(e->pwd);
80	if (e->envp)
81		env_free(e->envp);
82	free(e);
83}
84
85/* return NULL if eof or syntax error occurs;
86 * otherwise return a pointer to a new entry.
87 */
88entry *
89load_entry(FILE *file, void (*error_func)(const char *), struct passwd *pw,
90    char **envp)
91{
92	/* this function reads one crontab entry -- the next -- from a file.
93	 * it skips any leading blank lines, ignores comments, and returns
94	 * NULL if for any reason the entry can't be read and parsed.
95	 *
96	 * the entry is also parsed here.
97	 *
98	 * syntax:
99	 *   user crontab:
100	 *	minutes hours doms months dows cmd\n
101	 *   system crontab (/etc/crontab):
102	 *	minutes hours doms months dows USERNAME cmd\n
103	 */
104
105	ecode_e	ecode = e_none;
106	entry *e;
107	int ch;
108	char cmd[MAX_COMMAND];
109	char envstr[MAX_ENVSTR];
110	char **tenvp;
111
112	skip_comments(file);
113
114	ch = get_char(file);
115	if (ch == EOF)
116		return (NULL);
117
118	/* ch is now the first useful character of a useful line.
119	 * it may be an @special or it may be the first character
120	 * of a list of minutes.
121	 */
122
123	e = calloc(sizeof(entry), 1);
124	if (e == NULL) {
125		ecode = e_memory;
126		goto eof;
127	}
128
129	if (ch == '@') {
130		/* all of these should be flagged and load-limited; i.e.,
131		 * instead of @hourly meaning "0 * * * *" it should mean
132		 * "close to the front of every hour but not 'til the
133		 * system load is low".  Problems are: how do you know
134		 * what "low" means? (save me from /etc/cron.conf!) and:
135		 * how to guarantee low variance (how low is low?), which
136		 * means how to we run roughly every hour -- seems like
137		 * we need to keep a history or let the first hour set
138		 * the schedule, which means we aren't load-limited
139		 * anymore.  too much for my overloaded brain. (vix, jan90)
140		 * HINT
141		 */
142		ch = get_string(cmd, MAX_COMMAND, file, " \t\n");
143		if (!strcmp("reboot", cmd)) {
144			e->flags |= WHEN_REBOOT;
145		} else if (!strcmp("yearly", cmd) || !strcmp("annually", cmd)){
146			set_element(e->minute, FIRST_MINUTE, LAST_MINUTE,
147			    FIRST_MINUTE);
148			set_element(e->hour, FIRST_HOUR, LAST_HOUR, FIRST_HOUR);
149			set_element(e->dom, FIRST_DOM, LAST_DOM, FIRST_DOM);
150			set_element(e->month, FIRST_MONTH, LAST_MONTH,
151			    FIRST_MONTH);
152			set_range(e->dow, FIRST_DOW, LAST_DOW, FIRST_DOW,
153			    LAST_DOW, 1);
154			e->flags |= DOW_STAR;
155		} else if (!strcmp("monthly", cmd)) {
156			set_element(e->minute, FIRST_MINUTE, LAST_MINUTE,
157			    FIRST_MINUTE);
158			set_element(e->hour, FIRST_HOUR, LAST_HOUR, FIRST_HOUR);
159			set_element(e->dom, FIRST_DOM, LAST_DOM, FIRST_DOM);
160			set_range(e->month, FIRST_MONTH, LAST_MONTH,
161			    FIRST_MONTH, LAST_MONTH, 1);
162			set_range(e->dow, FIRST_DOW, LAST_DOW, FIRST_DOW,
163			    LAST_DOW, 1);
164			e->flags |= DOW_STAR;
165		} else if (!strcmp("weekly", cmd)) {
166			set_element(e->minute, FIRST_MINUTE, LAST_MINUTE,
167			    FIRST_MINUTE);
168			set_element(e->hour, FIRST_HOUR, LAST_HOUR, FIRST_HOUR);
169			set_range(e->dom, FIRST_DOM, LAST_DOM, FIRST_DOM,
170			    LAST_DOM, 1);
171			set_range(e->month, FIRST_MONTH, LAST_MONTH,
172			    FIRST_MONTH, LAST_MONTH, 1);
173			set_element(e->dow, FIRST_DOW, LAST_DOW, FIRST_DOW);
174			e->flags |= DOW_STAR;
175		} else if (!strcmp("daily", cmd) || !strcmp("midnight", cmd)) {
176			set_element(e->minute, FIRST_MINUTE, LAST_MINUTE,
177			    FIRST_MINUTE);
178			set_element(e->hour, FIRST_HOUR, LAST_HOUR, FIRST_HOUR);
179			set_range(e->dom, FIRST_DOM, LAST_DOM, FIRST_DOM,
180			    LAST_DOM, 1);
181			set_range(e->month, FIRST_MONTH, LAST_MONTH,
182			    FIRST_MONTH, LAST_MONTH, 1);
183			set_range(e->dow, FIRST_DOW, LAST_DOW, FIRST_DOW,
184			    LAST_DOW, 1);
185		} else if (!strcmp("hourly", cmd)) {
186			set_element(e->minute, FIRST_MINUTE, LAST_MINUTE,
187			    FIRST_MINUTE);
188			set_range(e->hour, FIRST_HOUR, LAST_HOUR, FIRST_HOUR,
189			    LAST_HOUR, 1);
190			set_range(e->dom, FIRST_DOM, LAST_DOM, FIRST_DOM,
191			    LAST_DOM, 1);
192			set_range(e->month, FIRST_MONTH, LAST_MONTH,
193			    FIRST_MONTH, LAST_MONTH, 1);
194			set_range(e->dow, FIRST_DOW, LAST_DOW,
195			    FIRST_DOW, LAST_DOW, 1);
196			e->flags |= HR_STAR;
197		} else {
198			ecode = e_timespec;
199			goto eof;
200		}
201		/* Advance past whitespace between shortcut and
202		 * username/command.
203		 */
204		Skip_Blanks(ch, file);
205		if (ch == EOF || ch == '\n') {
206			ecode = e_cmd;
207			goto eof;
208		}
209	} else {
210		if (ch == '*')
211			e->flags |= MIN_STAR;
212		ch = get_list(e->minute, FIRST_MINUTE, LAST_MINUTE,
213		    NULL, ch, file);
214		if (ch == EOF) {
215			ecode = e_minute;
216			goto eof;
217		}
218
219		/* hours
220		 */
221
222		if (ch == '*')
223			e->flags |= HR_STAR;
224		ch = get_list(e->hour, FIRST_HOUR, LAST_HOUR,
225		    NULL, ch, file);
226		if (ch == EOF) {
227			ecode = e_hour;
228			goto eof;
229		}
230
231		/* DOM (days of month)
232		 */
233
234		if (ch == '*')
235			e->flags |= DOM_STAR;
236		ch = get_list(e->dom, FIRST_DOM, LAST_DOM,
237		    NULL, ch, file);
238		if (ch == EOF) {
239			ecode = e_dom;
240			goto eof;
241		}
242
243		/* month
244		 */
245
246		ch = get_list(e->month, FIRST_MONTH, LAST_MONTH,
247		    MonthNames, ch, file);
248		if (ch == EOF) {
249			ecode = e_month;
250			goto eof;
251		}
252
253		/* DOW (days of week)
254		 */
255
256		if (ch == '*')
257			e->flags |= DOW_STAR;
258		ch = get_list(e->dow, FIRST_DOW, LAST_DOW,
259		    DowNames, ch, file);
260		if (ch == EOF) {
261			ecode = e_dow;
262			goto eof;
263		}
264	}
265
266	/* make sundays equivalent */
267	if (bit_test(e->dow, 0) || bit_test(e->dow, 7)) {
268		bit_set(e->dow, 0);
269		bit_set(e->dow, 7);
270	}
271
272	/* check for permature EOL and catch a common typo */
273	if (ch == '\n' || ch == '*') {
274		ecode = e_cmd;
275		goto eof;
276	}
277
278	if (!pw) {
279		char		*username = cmd;	/* temp buffer */
280
281		unget_char(ch, file);
282		ch = get_string(username, MAX_COMMAND, file, " \t\n");
283
284		if (ch == EOF || ch == '\n' || ch == '*') {
285			ecode = e_cmd;
286			goto eof;
287		}
288		Skip_Blanks(ch, file)
289
290		pw = getpwnam(username);
291		if (pw == NULL) {
292			ecode = e_username;
293			goto eof;
294		}
295	}
296
297	if ((e->pwd = pw_dup(pw)) == NULL) {
298		ecode = e_memory;
299		goto eof;
300	}
301	explicit_bzero(e->pwd->pw_passwd, strlen(e->pwd->pw_passwd));
302
303	/* copy and fix up environment.  some variables are just defaults and
304	 * others are overrides.
305	 */
306	if ((e->envp = env_copy(envp)) == NULL) {
307		ecode = e_memory;
308		goto eof;
309	}
310	if (!env_get("SHELL", e->envp)) {
311		if (snprintf(envstr, sizeof envstr, "SHELL=%s", _PATH_BSHELL) >=
312		    sizeof(envstr))
313			syslog(LOG_ERR, "(CRON) ERROR (can't set SHELL)");
314		else {
315			if ((tenvp = env_set(e->envp, envstr)) == NULL) {
316				ecode = e_memory;
317				goto eof;
318			}
319			e->envp = tenvp;
320		}
321	}
322	if (!env_get("HOME", e->envp)) {
323		if (snprintf(envstr, sizeof envstr, "HOME=%s", pw->pw_dir) >=
324		    sizeof(envstr))
325			syslog(LOG_ERR, "(CRON) ERROR (can't set HOME)");
326		else {
327			if ((tenvp = env_set(e->envp, envstr)) == NULL) {
328				ecode = e_memory;
329				goto eof;
330			}
331			e->envp = tenvp;
332		}
333	}
334	if (snprintf(envstr, sizeof envstr, "LOGNAME=%s", pw->pw_name) >=
335		sizeof(envstr))
336		syslog(LOG_ERR, "(CRON) ERROR (can't set LOGNAME)");
337	else {
338		if ((tenvp = env_set(e->envp, envstr)) == NULL) {
339			ecode = e_memory;
340			goto eof;
341		}
342		e->envp = tenvp;
343	}
344	if (snprintf(envstr, sizeof envstr, "USER=%s", pw->pw_name) >=
345		sizeof(envstr))
346		syslog(LOG_ERR, "(CRON) ERROR (can't set USER)");
347	else {
348		if ((tenvp = env_set(e->envp, envstr)) == NULL) {
349			ecode = e_memory;
350			goto eof;
351		}
352		e->envp = tenvp;
353	}
354
355	/* An optional series of '-'-prefixed flags in getopt style can
356	 * occur before the command.
357	 */
358	while (ch == '-') {
359		int flags = 0, loop = 1;
360
361		while (loop) {
362			switch (ch = get_char(file)) {
363			case 'n':
364				flags |= MAIL_WHEN_ERR;
365				break;
366			case 'q':
367				flags |= DONT_LOG;
368				break;
369			case 's':
370				flags |= SINGLE_JOB;
371				break;
372			case ' ':
373			case '\t':
374				Skip_Blanks(ch, file)
375				loop = 0;
376				break;
377			case EOF:
378			case '\n':
379				ecode = e_cmd;
380				goto eof;
381			default:
382				ecode = e_flags;
383				goto eof;
384			}
385		}
386
387		if (flags == 0) {
388			ecode = e_flags;
389			goto eof;
390		}
391		e->flags |= flags;
392	}
393	unget_char(ch, file);
394
395	/* Everything up to the next \n or EOF is part of the command...
396	 * too bad we don't know in advance how long it will be, since we
397	 * need to malloc a string for it... so, we limit it to MAX_COMMAND.
398	 */
399	ch = get_string(cmd, MAX_COMMAND, file, "\n");
400
401	/* a file without a \n before the EOF is rude, so we'll complain...
402	 */
403	if (ch == EOF) {
404		ecode = e_cmd;
405		goto eof;
406	}
407
408	/* got the command in the 'cmd' string; save it in *e.
409	 */
410	if ((e->cmd = strdup(cmd)) == NULL) {
411		ecode = e_memory;
412		goto eof;
413	}
414
415	/* success, fini, return pointer to the entry we just created...
416	 */
417	return (e);
418
419 eof:
420	if (e)
421		free_entry(e);
422	while (ch != '\n' && !feof(file))
423		ch = get_char(file);
424	if (ecode != e_none && error_func)
425		(*error_func)(ecodes[(int)ecode]);
426	return (NULL);
427}
428
429static int
430get_list(bitstr_t *bits, int low, int high, const char *names[],
431	 int ch, FILE *file)
432{
433	int done;
434
435	/* we know that we point to a non-blank character here;
436	 * must do a Skip_Blanks before we exit, so that the
437	 * next call (or the code that picks up the cmd) can
438	 * assume the same thing.
439	 */
440
441	/* list = range {"," range}
442	 */
443
444	/* clear the bit string, since the default is 'off'.
445	 */
446	bit_nclear(bits, 0, high - low);
447
448	/* process all ranges
449	 */
450	done = FALSE;
451	while (!done) {
452		if ((ch = get_range(bits, low, high, names, ch, file)) == EOF)
453			return (EOF);
454		if (ch == ',')
455			ch = get_char(file);
456		else
457			done = TRUE;
458	}
459
460	/* exiting.  skip to some blanks, then skip over the blanks.
461	 */
462	Skip_Nonblanks(ch, file)
463	Skip_Blanks(ch, file)
464
465	return (ch);
466}
467
468
469static int
470get_range(bitstr_t *bits, int low, int high, const char *names[],
471	  int ch, FILE *file)
472{
473	/* range = number |
474	 * [number] "~" [number] ["/" number] |
475	 * number "-" number ["/" number]
476	 */
477
478	int num1, num2, num3, rndstep;
479
480	num1 = low;
481	num2 = high;
482	rndstep = 0;
483
484	if (ch == '*') {
485		/* '*' means [low, high] but can still be modified by /step
486		 */
487		ch = get_char(file);
488		if (ch == EOF)
489			return (EOF);
490	} else {
491		if (ch != '~') {
492			ch = get_number(&num1, low, names, ch, file, ",-~ \t\n");
493			if (ch == EOF)
494				return (EOF);
495		}
496
497		switch (ch) {
498		case '-':
499			/* eat the dash
500			 */
501			ch = get_char(file);
502			if (ch == EOF)
503				return (EOF);
504
505			/* get the number following the dash
506			 */
507			ch = get_number(&num2, low, names, ch, file, "/, \t\n");
508			if (ch == EOF || num1 > num2)
509				return (EOF);
510			break;
511		case '~':
512			/* eat the tilde
513			 */
514			ch = get_char(file);
515			if (ch == EOF)
516				return (EOF);
517
518			/* get the (optional) number following the tilde
519			 */
520			ch = get_number(&num2, low, names, ch, file, "/, \t\n");
521			if (ch == EOF) {
522				/* no second number, check for valid terminator
523				 */
524				ch = get_char(file);
525				if (!strchr("/, \t\n", ch)) {
526					unget_char(ch, file);
527					return (EOF);
528				}
529			}
530			if (ch == EOF || num1 > num2) {
531				unget_char(ch, file);
532				return (EOF);
533			}
534
535			/* we must perform the bounds checking ourselves
536			 */
537			if (num1 < low || num2 > high)
538				return (EOF);
539
540			if (ch == '/') {
541				/* randomize the step value instead of num1
542				 */
543				rndstep = 1;
544				break;
545			}
546
547			/* get a random number in the interval [num1, num2]
548			 */
549			num3 = num1;
550			num1 = arc4random_uniform(num2 - num3 + 1) + num3;
551			/* FALLTHROUGH */
552		default:
553			/* not a range, it's a single number.
554			 */
555			if (set_element(bits, low, high, num1) == EOF) {
556				unget_char(ch, file);
557				return (EOF);
558			}
559			return (ch);
560		}
561	}
562
563	/* check for step size
564	 */
565	if (ch == '/') {
566		/* eat the slash
567		 */
568		ch = get_char(file);
569		if (ch == EOF)
570			return (EOF);
571
572		/* get the step size -- note: we don't pass the
573		 * names here, because the number is not an
574		 * element id, it's a step size.  'low' is
575		 * sent as a 0 since there is no offset either.
576		 */
577		ch = get_number(&num3, 0, NULL, ch, file, ", \t\n");
578		if (ch == EOF || num3 == 0)
579			return (EOF);
580		if (rndstep) {
581			/*
582			 * use a random offset smaller than the step size
583			 * and the difference between high and low values.
584			 */
585			num1 += arc4random_uniform(MINIMUM(num3, num2 - num1));
586		}
587	} else {
588		/* no step.  default==1.
589		 */
590		num3 = 1;
591	}
592
593	/* range. set all elements from num1 to num2, stepping
594	 * by num3.  (the step is a downward-compatible extension
595	 * proposed conceptually by bob@acornrc, syntactically
596	 * designed then implemented by paul vixie).
597	 */
598	if (set_range(bits, low, high, num1, num2, num3) == EOF) {
599		unget_char(ch, file);
600		return (EOF);
601	}
602
603	return (ch);
604}
605
606static int
607get_number(int *numptr, int low, const char *names[], int ch, FILE *file,
608    const char *terms)
609{
610	char temp[MAX_TEMPSTR], *pc;
611	int len, i;
612
613	pc = temp;
614	len = 0;
615
616	/* first look for a number */
617	while (isdigit((unsigned char)ch)) {
618		if (++len >= MAX_TEMPSTR)
619			goto bad;
620		*pc++ = ch;
621		ch = get_char(file);
622	}
623	*pc = '\0';
624	if (len != 0) {
625		/* got a number, check for valid terminator */
626		if (!strchr(terms, ch))
627			goto bad;
628		*numptr = atoi(temp);
629		return (ch);
630	}
631
632	/* no numbers, look for a string if we have any */
633	if (names) {
634		while (isalpha((unsigned char)ch)) {
635			if (++len >= MAX_TEMPSTR)
636				goto bad;
637			*pc++ = ch;
638			ch = get_char(file);
639		}
640		*pc = '\0';
641		if (len != 0 && strchr(terms, ch)) {
642			for (i = 0;  names[i] != NULL;  i++) {
643				if (!strcasecmp(names[i], temp)) {
644					*numptr = i+low;
645					return (ch);
646				}
647			}
648		}
649	}
650
651bad:
652	unget_char(ch, file);
653	return (EOF);
654}
655
656static int
657set_element(bitstr_t *bits, int low, int high, int number)
658{
659
660	if (number < low || number > high)
661		return (EOF);
662	number -= low;
663
664	bit_set(bits, number);
665	return (0);
666}
667
668static int
669set_range(bitstr_t *bits, int low, int high, int start, int stop, int step)
670{
671	int i;
672
673	if (start < low || stop > high)
674		return (EOF);
675	start -= low;
676	stop -= low;
677
678	if (step == 1) {
679		bit_nset(bits, start, stop);
680	} else {
681		for (i = start; i <= stop; i += step)
682			bit_set(bits, i);
683	}
684	return (0);
685}
686