[net-next-2.6.git] / net / netfilter / xt_time.c

/*
 *	xt_time
 *	Copyright © CC Computer Consultants GmbH, 2007
 *
 *	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).
	 * -1 and +1 map Sunday properly onto 7.
	 */
	r->weekday = (4 + r->dse - 1) % 7 + 1;
}

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)) {
		/* use days_since_leapyear[] in a leap year */
		for (i = ARRAY_SIZE(days_since_leapyear) - 1;
		    i > 0 && days_since_leapyear[i] > w; --i)
			/* just loop */;
		r->monthday = w - days_since_leapyear[i] + 1;
	} else {
		for (i = ARRAY_SIZE(days_since_year) - 1;
		    i > 0 && days_since_year[i] > w; --i)
			/* just loop */;
		r->monthday = w - days_since_year[i] + 1;
	}

	r->month    = i + 1;
	return;
}

static bool
time_mt(const struct sk_buff *skb, const struct xt_action_param *par)
{
	const struct xt_time_info *info = par->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);
	stamp = div_s64(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 int time_mt_check(const struct xt_mtchk_param *par)
{
	const struct xt_time_info *info = par->matchinfo;

	if (info->daytime_start > XT_TIME_MAX_DAYTIME ||
	    info->daytime_stop > XT_TIME_MAX_DAYTIME) {
		pr_info("invalid argument - start or "
			"stop time greater than 23:59:59\n");
		return -EDOM;
	}

	return 0;
}

static struct xt_match xt_time_mt_reg __read_mostly = {
	.name       = "time",
	.family     = NFPROTO_UNSPEC,
	.match      = time_mt,
	.checkentry = time_mt_check,
	.matchsize  = sizeof(struct xt_time_info),
	.me         = THIS_MODULE,
};

static int __init time_mt_init(void)
{
	int minutes = sys_tz.tz_minuteswest;

	if (minutes < 0) /* east of Greenwich */
		printk(KERN_INFO KBUILD_MODNAME
		       ": kernel timezone is +%02d%02d\n",
		       -minutes / 60, -minutes % 60);
	else /* west of Greenwich */
		printk(KERN_INFO KBUILD_MODNAME
		       ": kernel timezone is -%02d%02d\n",
		       minutes / 60, minutes % 60);

	return xt_register_match(&xt_time_mt_reg);
}

static void __exit time_mt_exit(void)
{
	xt_unregister_match(&xt_time_mt_reg);
}

module_init(time_mt_init);
module_exit(time_mt_exit);
MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
MODULE_DESCRIPTION("Xtables: time-based matching");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_time");
MODULE_ALIAS("ip6t_time");
Commit	Line	Data
ee4411a1 JE	1	/*
ee4411a1 JE	2	* xt_time
ba5dc275	3	* Copyright © CC Computer Consultants GmbH, 2007
ee4411a1 JE	4	*
	5	* based on ipt_time by Fabrice MARIE <fabrice@netfilter.org>
	6	* This is a module which is used for time matching
	7	* It is using some modified code from dietlibc (localtime() function)
	8	* that you can find at http://www.fefe.de/dietlibc/
	9	* This file is distributed under the terms of the GNU General Public
	10	* License (GPL). Copies of the GPL can be obtained from gnu.org/gpl.
	11	*/
	12	#include <linux/ktime.h>
	13	#include <linux/module.h>
	14	#include <linux/skbuff.h>
	15	#include <linux/types.h>
	16	#include <linux/netfilter/x_tables.h>
	17	#include <linux/netfilter/xt_time.h>
	18
	19	struct xtm {
	20	u_int8_t month; /* (1-12) */
	21	u_int8_t monthday; /* (1-31) */
	22	u_int8_t weekday; /* (1-7) */
	23	u_int8_t hour; /* (0-23) */
	24	u_int8_t minute; /* (0-59) */
	25	u_int8_t second; /* (0-59) */
	26	unsigned int dse;
	27	};
	28
	29	extern struct timezone sys_tz; /* ouch */
	30
	31	static const u_int16_t days_since_year[] = {
	32	0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334,
	33	};
	34
	35	static const u_int16_t days_since_leapyear[] = {
	36	0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335,
	37	};
	38
	39	/*
	40	* Since time progresses forward, it is best to organize this array in reverse,
	41	* to minimize lookup time.
	42	*/
	43	enum {
	44	DSE_FIRST = 2039,
	45	};
	46	static const u_int16_t days_since_epoch[] = {
	47	/* 2039 - 2030 */
	48	25202, 24837, 24472, 24106, 23741, 23376, 23011, 22645, 22280, 21915,
	49	/* 2029 - 2020 */
	50	21550, 21184, 20819, 20454, 20089, 19723, 19358, 18993, 18628, 18262,
	51	/* 2019 - 2010 */
	52	17897, 17532, 17167, 16801, 16436, 16071, 15706, 15340, 14975, 14610,
	53	/* 2009 - 2000 */
	54	14245, 13879, 13514, 13149, 12784, 12418, 12053, 11688, 11323, 10957,
	55	/* 1999 - 1990 */
	56	10592, 10227, 9862, 9496, 9131, 8766, 8401, 8035, 7670, 7305,
	57	/* 1989 - 1980 */
	58	6940, 6574, 6209, 5844, 5479, 5113, 4748, 4383, 4018, 3652,
	59	/* 1979 - 1970 */
	60	3287, 2922, 2557, 2191, 1826, 1461, 1096, 730, 365, 0,
	61	};
	62
	63	static inline bool is_leap(unsigned int y)
	64	{
	65	return y % 4 == 0 && (y % 100 != 0 \|\| y % 400 == 0);
	66	}
	67
68	/*
69	* Each network packet has a (nano)seconds-since-the-epoch (SSTE) timestamp.
70	* Since we match against days and daytime, the SSTE value needs to be
71	* computed back into human-readable dates.
72	*
73	* This is done in three separate functions so that the most expensive
74	* calculations are done last, in case a "simple match" can be found earlier.
75	*/
76	static inline unsigned int localtime_1(struct xtm *r, time_t time)
77	{
78	unsigned int v, w;
79
80	/* Each day has 86400s, so finding the hour/minute is actually easy. */
81	v = time % 86400;
82	r->second = v % 60;
83	w = v / 60;
84	r->minute = w % 60;
85	r->hour = w / 60;
86	return v;
87	}
88
89	static inline void localtime_2(struct xtm *r, time_t time)
90	{
91	/*
92	* Here comes the rest (weekday, monthday). First, divide the SSTE
93	* by seconds-per-day to get the number of _days_ since the epoch.
94	*/
95	r->dse = time / 86400;
96
4f4c9430 JE	97	/*
	98	* 1970-01-01 (w=0) was a Thursday (4).
	99	* -1 and +1 map Sunday properly onto 7.
	100	*/
	101	r->weekday = (4 + r->dse - 1) % 7 + 1;
ee4411a1 JE	102	}
	103
	104	static void localtime_3(struct xtm *r, time_t time)
	105	{
	106	unsigned int year, i, w = r->dse;
	107
	108	/*
	109	* In each year, a certain number of days-since-the-epoch have passed.
	110	* Find the year that is closest to said days.
	111	*
	112	* Consider, for example, w=21612 (2029-03-04). Loop will abort on
	113	* dse[i] <= w, which happens when dse[i] == 21550. This implies
	114	* year == 2009. w will then be 62.
	115	*/
	116	for (i = 0, year = DSE_FIRST; days_since_epoch[i] > w;
	117	++i, --year)
	118	/* just loop */;
	119
	120	w -= days_since_epoch[i];
	121
	122	/*
	123	* By now we have the current year, and the day of the year.
	124	* r->yearday = w;
	125	*
	126	* On to finding the month (like above). In each month, a certain
	127	* number of days-since-New Year have passed, and find the closest
	128	* one.
	129	*
	130	* Consider w=62 (in a non-leap year). Loop will abort on
	131	* dsy[i] < w, which happens when dsy[i] == 31+28 (i == 2).
	132	* Concludes i == 2, i.e. 3rd month => March.
	133	*
	134	* (A different approach to use would be to subtract a monthlength
	135	* from w repeatedly while counting.)
	136	*/
	137	if (is_leap(year)) {
2cdc5575	138	/* use days_since_leapyear[] in a leap year */
ee4411a1	139	for (i = ARRAY_SIZE(days_since_leapyear) - 1;
2cdc5575	140	i > 0 && days_since_leapyear[i] > w; --i)
ee4411a1	141	/* just loop */;
2cdc5575	142	r->monthday = w - days_since_leapyear[i] + 1;
ee4411a1 JE	143	} else {
	144	for (i = ARRAY_SIZE(days_since_year) - 1;
	145	i > 0 && days_since_year[i] > w; --i)
	146	/* just loop */;
2cdc5575	147	r->monthday = w - days_since_year[i] + 1;
ee4411a1 JE	148	}
	149
	150	r->month = i + 1;
ee4411a1 JE	151	return;
	152	}
	153
d3c5ee6d	154	static bool
4b560b44	155	time_mt(const struct sk_buff skb, const struct xt_action_param par)
ee4411a1	156	{
f7108a20	157	const struct xt_time_info *info = par->matchinfo;
ee4411a1 JE	158	unsigned int packet_time;
	159	struct xtm current_time;
	160	s64 stamp;
	161
	162	/*
	163	* We cannot use get_seconds() instead of __net_timestamp() here.
	164	* Suppose you have two rules:
	165	* 1. match before 13:00
	166	* 2. match after 13:00
	167	* If you match against processing time (get_seconds) it
	168	* may happen that the same packet matches both rules if
	169	* it arrived at the right moment before 13:00.
	170	*/
	171	if (skb->tstamp.tv64 == 0)
	172	__net_timestamp((struct sk_buff *)skb);
	173
53756524	174	stamp = ktime_to_ns(skb->tstamp);
280763c0	175	stamp = div_s64(stamp, NSEC_PER_SEC);
ee4411a1 JE	176
	177	if (info->flags & XT_TIME_LOCAL_TZ)
	178	/* Adjust for local timezone */
	179	stamp -= 60 * sys_tz.tz_minuteswest;
	180
	181	/*
	182	* xt_time will match when _all_ of the following hold:
	183	* - 'now' is in the global time range date_start..date_end
	184	* - 'now' is in the monthday mask
	185	* - 'now' is in the weekday mask
	186	* - 'now' is in the daytime range time_start..time_end
	187	* (and by default, libxt_time will set these so as to match)
	188	*/
	189
	190	if (stamp < info->date_start \|\| stamp > info->date_stop)
	191	return false;
	192
	193	packet_time = localtime_1(&current_time, stamp);
	194
	195	if (info->daytime_start < info->daytime_stop) {
	196	if (packet_time < info->daytime_start \|\|
	197	packet_time > info->daytime_stop)
	198	return false;
	199	} else {
	200	if (packet_time < info->daytime_start &&
	201	packet_time > info->daytime_stop)
	202	return false;
	203	}
	204
	205	localtime_2(&current_time, stamp);
	206
	207	if (!(info->weekdays_match & (1 << current_time.weekday)))
	208	return false;
	209
	210	/* Do not spend time computing monthday if all days match anyway */
	211	if (info->monthdays_match != XT_TIME_ALL_MONTHDAYS) {
	212	localtime_3(&current_time, stamp);
	213	if (!(info->monthdays_match & (1 << current_time.monthday)))
	214	return false;
	215	}
	216
	217	return true;
	218	}
	219
b0f38452	220	static int time_mt_check(const struct xt_mtchk_param *par)
ee4411a1	221	{
9b4fce7a	222	const struct xt_time_info *info = par->matchinfo;
ee4411a1 JE	223
	224	if (info->daytime_start > XT_TIME_MAX_DAYTIME \|\|
	225	info->daytime_stop > XT_TIME_MAX_DAYTIME) {
ff67e4e4 JE	226	pr_info("invalid argument - start or "
ff67e4e4 JE	227	"stop time greater than 23:59:59\n");
4a5a5c73	228	return -EDOM;
ee4411a1 JE	229	}
ee4411a1 JE	230
bd414ee6	231	return 0;
ee4411a1 JE	232	}
ee4411a1 JE	233
55b69e91 JE	234	static struct xt_match xt_time_mt_reg __read_mostly = {
	235	.name = "time",
	236	.family = NFPROTO_UNSPEC,
	237	.match = time_mt,
	238	.checkentry = time_mt_check,
	239	.matchsize = sizeof(struct xt_time_info),
	240	.me = THIS_MODULE,
ee4411a1 JE	241	};
ee4411a1 JE	242
d3c5ee6d	243	static int __init time_mt_init(void)
ee4411a1	244	{
e6210f3b JE	245	int minutes = sys_tz.tz_minuteswest;
	246
	247	if (minutes < 0) /* east of Greenwich */
	248	printk(KERN_INFO KBUILD_MODNAME
	249	": kernel timezone is +%02d%02d\n",
	250	-minutes / 60, -minutes % 60);
	251	else /* west of Greenwich */
	252	printk(KERN_INFO KBUILD_MODNAME
	253	": kernel timezone is -%02d%02d\n",
	254	minutes / 60, minutes % 60);
	255
55b69e91	256	return xt_register_match(&xt_time_mt_reg);
ee4411a1 JE	257	}
ee4411a1 JE	258
d3c5ee6d	259	static void __exit time_mt_exit(void)
ee4411a1	260	{
55b69e91	261	xt_unregister_match(&xt_time_mt_reg);
ee4411a1 JE	262	}
ee4411a1 JE	263
d3c5ee6d JE	264	module_init(time_mt_init);
d3c5ee6d JE	265	module_exit(time_mt_exit);
408ffaa4	266	MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
2ae15b64	267	MODULE_DESCRIPTION("Xtables: time-based matching");
ee4411a1 JE	268	MODULE_LICENSE("GPL");
	269	MODULE_ALIAS("ipt_time");
	270	MODULE_ALIAS("ip6t_time");