diff options
Diffstat (limited to 'net/netfilter/xt_time.c')
| -rw-r--r-- | net/netfilter/xt_time.c | 260 |
1 files changed, 260 insertions, 0 deletions
diff --git a/net/netfilter/xt_time.c b/net/netfilter/xt_time.c new file mode 100644 index 0000000..29375ba --- /dev/null +++ b/net/netfilter/xt_time.c @@ -0,0 +1,260 @@ +/* + * 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). + * -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_match_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 bool 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) { + 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_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) +{ + 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@computergmbh.de>"); +MODULE_DESCRIPTION("Xtables: time-based matching"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("ipt_time"); +MODULE_ALIAS("ip6t_time"); |
