[NETFILTER]: x_tables: add xt_time match (ee4411a1) · Commits · 戴 / test

include/linux/netfilter/xt_time.h

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		#ifndef _XT_TIME_H
		#define _XT_TIME_H 1

		struct xt_time_info {
		u_int32_t date_start;
		u_int32_t date_stop;
		u_int32_t daytime_start;
		u_int32_t daytime_stop;
		u_int32_t monthdays_match;
		u_int8_t weekdays_match;
		u_int8_t flags;
		};

		enum {
		/* Match against local time (instead of UTC) */
		XT_TIME_LOCAL_TZ = 1 << 0,

		/* Shortcuts */
		XT_TIME_ALL_MONTHDAYS = 0xFFFFFFFE,
		XT_TIME_ALL_WEEKDAYS = 0xFE,
		XT_TIME_MIN_DAYTIME = 0,
		XT_TIME_MAX_DAYTIME = 24 * 60 * 60 - 1,
		};

		#endif /* _XT_TIME_H */

net/netfilter/Kconfig

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		@@ -665,6 +665,20 @@ config NETFILTER_XT_MATCH_TCPMSS

		To compile it as a module, choose M here. If unsure, say N.

		config NETFILTER_XT_MATCH_TIME
		tristate '"time" match support'
		depends on NETFILTER_XTABLES
		---help---
		This option adds a "time" match, which allows you to match based on
		the packet arrival time (at the machine which netfilter is running)
		on) or departure time/date (for locally generated packets).

		If you say Y here, try `iptables -m time --help` for
		more information.

		If you want to compile it as a module, say M here.
		If unsure, say N.

		config NETFILTER_XT_MATCH_U32
		tristate '"u32" match support'
		depends on NETFILTER_XTABLES

net/netfilter/Makefile

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		@@ -73,6 +73,7 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_SCTP) += xt_sctp.o
		obj-$(CONFIG_NETFILTER_XT_MATCH_STATE) += xt_state.o
		obj-$(CONFIG_NETFILTER_XT_MATCH_STATISTIC) += xt_statistic.o
		obj-$(CONFIG_NETFILTER_XT_MATCH_STRING) += xt_string.o
		obj-$(CONFIG_NETFILTER_XT_MATCH_TIME) += xt_time.o
		obj-$(CONFIG_NETFILTER_XT_MATCH_TCPMSS) += xt_tcpmss.o
		obj-$(CONFIG_NETFILTER_XT_MATCH_PHYSDEV) += xt_physdev.o
		obj-$(CONFIG_NETFILTER_XT_MATCH_U32) += xt_u32.o

net/netfilter/xt_time.c

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		/*
		* xt_time
		* Copyright © Jan Engelhardt <jengelh@computergmbh.de>, 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). */
		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 = skb->tstamp.tv64;
		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");

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