/* *	xt_time *	Copyright ? CC Computer Consultants GmbH, 2007 *	Contact: <jengelh@computergmbh.de> * *	based on ipt_time by Fabrice MARIE <fabrice@netfilter.org> *	This is a module which is used for time matching *	It is using some modified code from dietlibc (localtime() function) *	that you can find at http://www.fefe.de/dietlibc/ *	This file is distributed under the terms of the GNU General Public *	License (GPL). Copies of the GPL can be obtained from gnu.org/gpl. */#include <linux/ktime.h>#include <linux/module.h>#include <linux/skbuff.h>#include <linux/types.h>#include <linux/netfilter/x_tables.h>#include <linux/netfilter/xt_time.h>struct xtm {	u_int8_t month;    /* (1-12) */	u_int8_t monthday; /* (1-31) */	u_int8_t weekday;  /* (1-7) */	u_int8_t hour;     /* (0-23) */	u_int8_t minute;   /* (0-59) */	u_int8_t second;   /* (0-59) */	unsigned int dse;};extern struct timezone sys_tz; /* ouch */static const u_int16_t days_since_year[] = {	0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334,};static const u_int16_t days_since_leapyear[] = {	0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335,};/* * Since time progresses forward, it is best to organize this array in reverse, * to minimize lookup time. */enum {	DSE_FIRST = 2039,};static const u_int16_t days_since_epoch[] = {	/* 2039 - 2030 */	25202, 24837, 24472, 24106, 23741, 23376, 23011, 22645, 22280, 21915,	/* 2029 - 2020 */	21550, 21184, 20819, 20454, 20089, 19723, 19358, 18993, 18628, 18262,	/* 2019 - 2010 */	17897, 17532, 17167, 16801, 16436, 16071, 15706, 15340, 14975, 14610,	/* 2009 - 2000 */	14245, 13879, 13514, 13149, 12784, 12418, 12053, 11688, 11323, 10957,	/* 1999 - 1990 */	10592, 10227, 9862, 9496, 9131, 8766, 8401, 8035, 7670, 7305,	/* 1989 - 1980 */	6940, 6574, 6209, 5844, 5479, 5113, 4748, 4383, 4018, 3652,	/* 1979 - 1970 */	3287, 2922, 2557, 2191, 1826, 1461, 1096, 730, 365, 0,};static inline bool is_leap(unsigned int y){	return y % 4 == 0 && (y % 100 != 0 || y % 400 == 0);}/* * Each network packet has a (nano)seconds-since-the-epoch (SSTE) timestamp. * Since we match against days and daytime, the SSTE value needs to be * computed back into human-readable dates. * * This is done in three separate functions so that the most expensive * calculations are done last, in case a "simple match" can be found earlier. */static inline unsigned int localtime_1(struct xtm *r, time_t time){	unsigned int v, w;	/* Each day has 86400s, so finding the hour/minute is actually easy. */	v         = time % 86400;	r->second = v % 60;	w         = v / 60;	r->minute = w % 60;	r->hour   = w / 60;	return v;}static inline void localtime_2(struct xtm *r, time_t time){	/*	 * Here comes the rest (weekday, monthday). First, divide the SSTE	 * by seconds-per-day to get the number of _days_ since the epoch.	 */	r->dse = time / 86400;	/* 1970-01-01 (w=0) was a Thursday (4). */	r->weekday = (4 + r->dse) % 7;}static void localtime_3(struct xtm *r, time_t time){	unsigned int year, i, w = r->dse;	/*	 * In each year, a certain number of days-since-the-epoch have passed.	 * Find the year that is closest to said days.	 *	 * Consider, for example, w=21612 (2029-03-04). Loop will abort on	 * dse[i] <= w, which happens when dse[i] == 21550. This implies	 * year == 2009. w will then be 62.	 */	for (i = 0, year = DSE_FIRST; days_since_epoch[i] > w;	    ++i, --year)		/* just loop */;	w -= days_since_epoch[i];	/*	 * By now we have the current year, and the day of the year.	 * r->yearday = w;	 *	 * On to finding the month (like above). In each month, a certain	 * number of days-since-New Year have passed, and find the closest	 * one.	 *	 * Consider w=62 (in a non-leap year). Loop will abort on	 * dsy[i] < w, which happens when dsy[i] == 31+28 (i == 2).	 * Concludes i == 2, i.e. 3rd month => March.	 *	 * (A different approach to use would be to subtract a monthlength	 * from w repeatedly while counting.)	 */	if (is_leap(year)) {		for (i = ARRAY_SIZE(days_since_leapyear) - 1;		    i > 0 && days_since_year[i] > w; --i)			/* just loop */;	} else {		for (i = ARRAY_SIZE(days_since_year) - 1;		    i > 0 && days_since_year[i] > w; --i)			/* just loop */;	}	r->month    = i + 1;	r->monthday = w - days_since_year[i] + 1;	return;}static bool xt_time_match(const struct sk_buff *skb,                          const struct net_device *in,                          const struct net_device *out,                          const struct xt_match *match, const void *matchinfo,                          int offset, unsigned int protoff, bool *hotdrop){	const struct xt_time_info *info = matchinfo;	unsigned int packet_time;	struct xtm current_time;	s64 stamp;	/*	 * We cannot use get_seconds() instead of __net_timestamp() here.	 * Suppose you have two rules:	 * 	1. match before 13:00	 * 	2. match after 13:00	 * If you match against processing time (get_seconds) it	 * may happen that the same packet matches both rules if	 * it arrived at the right moment before 13:00.	 */	if (skb->tstamp.tv64 == 0)		__net_timestamp((struct sk_buff *)skb);	stamp = ktime_to_ns(skb->tstamp);	do_div(stamp, NSEC_PER_SEC);	if (info->flags & XT_TIME_LOCAL_TZ)		/* Adjust for local timezone */		stamp -= 60 * sys_tz.tz_minuteswest;	/*	 * xt_time will match when _all_ of the following hold:	 *   - 'now' is in the global time range date_start..date_end	 *   - 'now' is in the monthday mask	 *   - 'now' is in the weekday mask	 *   - 'now' is in the daytime range time_start..time_end	 * (and by default, libxt_time will set these so as to match)	 */	if (stamp < info->date_start || stamp > info->date_stop)		return false;	packet_time = localtime_1(&current_time, stamp);	if (info->daytime_start < info->daytime_stop) {		if (packet_time < info->daytime_start ||		    packet_time > info->daytime_stop)			return false;	} else {		if (packet_time < info->daytime_start &&		    packet_time > info->daytime_stop)			return false;	}	localtime_2(&current_time, stamp);	if (!(info->weekdays_match & (1 << current_time.weekday)))		return false;	/* Do not spend time computing monthday if all days match anyway */	if (info->monthdays_match != XT_TIME_ALL_MONTHDAYS) {		localtime_3(&current_time, stamp);		if (!(info->monthdays_match & (1 << current_time.monthday)))			return false;	}	return true;}static bool xt_time_check(const char *tablename, const void *ip,                          const struct xt_match *match, void *matchinfo,                          unsigned int hook_mask){	struct xt_time_info *info = matchinfo;	if (info->daytime_start > XT_TIME_MAX_DAYTIME ||	    info->daytime_stop > XT_TIME_MAX_DAYTIME) {		printk(KERN_WARNING "xt_time: invalid argument - start or "		       "stop time greater than 23:59:59\n");		return false;	}	return true;}static struct xt_match xt_time_reg[] __read_mostly = {	{		.name       = "time",		.family     = AF_INET,		.match      = xt_time_match,		.matchsize  = sizeof(struct xt_time_info),		.checkentry = xt_time_check,		.me         = THIS_MODULE,	},	{		.name       = "time",		.family     = AF_INET6,		.match      = xt_time_match,		.matchsize  = sizeof(struct xt_time_info),		.checkentry = xt_time_check,		.me         = THIS_MODULE,	},};static int __init xt_time_init(void){	return xt_register_matches(xt_time_reg, ARRAY_SIZE(xt_time_reg));}static void __exit xt_time_exit(void){	xt_unregister_matches(xt_time_reg, ARRAY_SIZE(xt_time_reg));}module_init(xt_time_init);module_exit(xt_time_exit);MODULE_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");MODULE_DESCRIPTION("netfilter time match");MODULE_LICENSE("GPL");MODULE_ALIAS("ipt_time");MODULE_ALIAS("ip6t_time");