| /* |
| * 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(¤t_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(¤t_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(¤t_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"); |