3 * Copyright © CC Computer Consultants GmbH, 2007
4 * Contact: <jengelh@computergmbh.de>
6 * based on ipt_time by Fabrice MARIE <fabrice@netfilter.org>
7 * This is a module which is used for time matching
8 * It is using some modified code from dietlibc (localtime() function)
9 * that you can find at http://www.fefe.de/dietlibc/
10 * This file is distributed under the terms of the GNU General Public
11 * License (GPL). Copies of the GPL can be obtained from gnu.org/gpl.
13 #include <linux/ktime.h>
14 #include <linux/module.h>
15 #include <linux/skbuff.h>
16 #include <linux/types.h>
17 #include <linux/netfilter/x_tables.h>
18 #include <linux/netfilter/xt_time.h>
21 u_int8_t month; /* (1-12) */
22 u_int8_t monthday; /* (1-31) */
23 u_int8_t weekday; /* (1-7) */
24 u_int8_t hour; /* (0-23) */
25 u_int8_t minute; /* (0-59) */
26 u_int8_t second; /* (0-59) */
30 extern struct timezone sys_tz; /* ouch */
32 static const u_int16_t days_since_year[] = {
33 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334,
36 static const u_int16_t days_since_leapyear[] = {
37 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335,
41 * Since time progresses forward, it is best to organize this array in reverse,
42 * to minimize lookup time.
47 static const u_int16_t days_since_epoch[] = {
49 25202, 24837, 24472, 24106, 23741, 23376, 23011, 22645, 22280, 21915,
51 21550, 21184, 20819, 20454, 20089, 19723, 19358, 18993, 18628, 18262,
53 17897, 17532, 17167, 16801, 16436, 16071, 15706, 15340, 14975, 14610,
55 14245, 13879, 13514, 13149, 12784, 12418, 12053, 11688, 11323, 10957,
57 10592, 10227, 9862, 9496, 9131, 8766, 8401, 8035, 7670, 7305,
59 6940, 6574, 6209, 5844, 5479, 5113, 4748, 4383, 4018, 3652,
61 3287, 2922, 2557, 2191, 1826, 1461, 1096, 730, 365, 0,
64 static inline bool is_leap(unsigned int y)
66 return y % 4 == 0 && (y % 100 != 0 || y % 400 == 0);
70 * Each network packet has a (nano)seconds-since-the-epoch (SSTE) timestamp.
71 * Since we match against days and daytime, the SSTE value needs to be
72 * computed back into human-readable dates.
74 * This is done in three separate functions so that the most expensive
75 * calculations are done last, in case a "simple match" can be found earlier.
77 static inline unsigned int localtime_1(struct xtm *r, time_t time)
81 /* Each day has 86400s, so finding the hour/minute is actually easy. */
90 static inline void localtime_2(struct xtm *r, time_t time)
93 * Here comes the rest (weekday, monthday). First, divide the SSTE
94 * by seconds-per-day to get the number of _days_ since the epoch.
96 r->dse = time / 86400;
99 * 1970-01-01 (w=0) was a Thursday (4).
100 * -1 and +1 map Sunday properly onto 7.
102 r->weekday = (4 + r->dse - 1) % 7 + 1;
105 static void localtime_3(struct xtm *r, time_t time)
107 unsigned int year, i, w = r->dse;
110 * In each year, a certain number of days-since-the-epoch have passed.
111 * Find the year that is closest to said days.
113 * Consider, for example, w=21612 (2029-03-04). Loop will abort on
114 * dse[i] <= w, which happens when dse[i] == 21550. This implies
115 * year == 2009. w will then be 62.
117 for (i = 0, year = DSE_FIRST; days_since_epoch[i] > w;
121 w -= days_since_epoch[i];
124 * By now we have the current year, and the day of the year.
127 * On to finding the month (like above). In each month, a certain
128 * number of days-since-New Year have passed, and find the closest
131 * Consider w=62 (in a non-leap year). Loop will abort on
132 * dsy[i] < w, which happens when dsy[i] == 31+28 (i == 2).
133 * Concludes i == 2, i.e. 3rd month => March.
135 * (A different approach to use would be to subtract a monthlength
136 * from w repeatedly while counting.)
139 /* use days_since_leapyear[] in a leap year */
140 for (i = ARRAY_SIZE(days_since_leapyear) - 1;
141 i > 0 && days_since_leapyear[i] > w; --i)
143 r->monthday = w - days_since_leapyear[i] + 1;
145 for (i = ARRAY_SIZE(days_since_year) - 1;
146 i > 0 && days_since_year[i] > w; --i)
148 r->monthday = w - days_since_year[i] + 1;
156 time_mt(const struct sk_buff *skb, const struct net_device *in,
157 const struct net_device *out, const struct xt_match *match,
158 const void *matchinfo, int offset, unsigned int protoff, bool *hotdrop)
160 const struct xt_time_info *info = matchinfo;
161 unsigned int packet_time;
162 struct xtm current_time;
166 * We cannot use get_seconds() instead of __net_timestamp() here.
167 * Suppose you have two rules:
168 * 1. match before 13:00
169 * 2. match after 13:00
170 * If you match against processing time (get_seconds) it
171 * may happen that the same packet matches both rules if
172 * it arrived at the right moment before 13:00.
174 if (skb->tstamp.tv64 == 0)
175 __net_timestamp((struct sk_buff *)skb);
177 stamp = ktime_to_ns(skb->tstamp);
178 stamp = div_s64(stamp, NSEC_PER_SEC);
180 if (info->flags & XT_TIME_LOCAL_TZ)
181 /* Adjust for local timezone */
182 stamp -= 60 * sys_tz.tz_minuteswest;
185 * xt_time will match when _all_ of the following hold:
186 * - 'now' is in the global time range date_start..date_end
187 * - 'now' is in the monthday mask
188 * - 'now' is in the weekday mask
189 * - 'now' is in the daytime range time_start..time_end
190 * (and by default, libxt_time will set these so as to match)
193 if (stamp < info->date_start || stamp > info->date_stop)
196 packet_time = localtime_1(¤t_time, stamp);
198 if (info->daytime_start < info->daytime_stop) {
199 if (packet_time < info->daytime_start ||
200 packet_time > info->daytime_stop)
203 if (packet_time < info->daytime_start &&
204 packet_time > info->daytime_stop)
208 localtime_2(¤t_time, stamp);
210 if (!(info->weekdays_match & (1 << current_time.weekday)))
213 /* Do not spend time computing monthday if all days match anyway */
214 if (info->monthdays_match != XT_TIME_ALL_MONTHDAYS) {
215 localtime_3(¤t_time, stamp);
216 if (!(info->monthdays_match & (1 << current_time.monthday)))
224 time_mt_check(const char *tablename, const void *ip,
225 const struct xt_match *match, void *matchinfo,
226 unsigned int hook_mask)
228 const struct xt_time_info *info = matchinfo;
230 if (info->daytime_start > XT_TIME_MAX_DAYTIME ||
231 info->daytime_stop > XT_TIME_MAX_DAYTIME) {
232 printk(KERN_WARNING "xt_time: invalid argument - start or "
233 "stop time greater than 23:59:59\n");
240 static struct xt_match xt_time_mt_reg __read_mostly = {
242 .family = NFPROTO_UNSPEC,
244 .checkentry = time_mt_check,
245 .matchsize = sizeof(struct xt_time_info),
249 static int __init time_mt_init(void)
251 return xt_register_match(&xt_time_mt_reg);
254 static void __exit time_mt_exit(void)
256 xt_unregister_match(&xt_time_mt_reg);
259 module_init(time_mt_init);
260 module_exit(time_mt_exit);
261 MODULE_AUTHOR("Jan Engelhardt <jengelh@computergmbh.de>");
262 MODULE_DESCRIPTION("Xtables: time-based matching");
263 MODULE_LICENSE("GPL");
264 MODULE_ALIAS("ipt_time");
265 MODULE_ALIAS("ip6t_time");