net/ipv4/netfilter/ipt_time.c

   1 /*
   2   This is a module which is used for time matching
   3   It is using some modified code from dietlibc (localtime() function)
   4   that you can find at http://www.fefe.de/dietlibc/
   5   This file is distributed under the terms of the GNU General Public
   6   License (GPL). Copies of the GPL can be obtained from: ftp://prep.ai.mit.edu/pub/gnu/GPL
   7   2001-05-04 Fabrice MARIE <fabrice@netfilter.org> : initial development.
   8   2001-21-05 Fabrice MARIE <fabrice@netfilter.org> : bug fix in the match code,
   9      thanks to "Zeng Yu" <zengy@capitel.com.cn> for bug report.
  10   2001-26-09 Fabrice MARIE <fabrice@netfilter.org> : force the match to be in LOCAL_IN or PRE_ROUTING only.
  11   2001-30-11 Fabrice : added the possibility to use the match in FORWARD/OUTPUT with a little hack,
  12      added Nguyen Dang Phuoc Dong <dongnd@tlnet.com.vn> patch to support timezones.
  13   2004-05-02 Fabrice : added support for date matching, from an idea of Fabien COELHO.
  14 */
  15
  16 #include <linux/module.h>
  17 #include <linux/skbuff.h>
  18 #include <linux/netfilter_ipv4/ip_tables.h>
  19 #include <linux/netfilter_ipv4/ipt_time.h>
  20 #include <linux/time.h>
  21
  22 MODULE_AUTHOR("Fabrice MARIE <fabrice@netfilter.org>");
  23 MODULE_DESCRIPTION("Match arrival timestamp/date");
  24 MODULE_LICENSE("GPL");
  25
  26 struct tm
  27 {
  28         int tm_sec;                   /* Seconds.     [0-60] (1 leap second) */
  29         int tm_min;                   /* Minutes.     [0-59] */
  30         int tm_hour;                  /* Hours.       [0-23] */
  31         int tm_mday;                  /* Day.         [1-31] */
  32         int tm_mon;                   /* Month.       [0-11] */
  33         int tm_year;                  /* Year - 1900.  */
  34         int tm_wday;                  /* Day of week. [0-6] */
  35         int tm_yday;                  /* Days in year.[0-365] */
  36         int tm_isdst;                 /* DST.         [-1/0/1]*/
  37
  38         long int tm_gmtoff;           /* we don't care, we count from GMT */
  39         const char *tm_zone;          /* we don't care, we count from GMT */
  40 };
  41
  42 static void
  43 localtime(const u32 time, struct tm *r);
  44
  45 static int
  46 match(const struct sk_buff *skb,
  47       const struct net_device *in,
  48       const struct net_device *out,
  49       const struct xt_match *match,
  50       const void *matchinfo,
  51       int offset,
  52       unsigned int protoff,
  53       int *hotdrop)
  54 {
  55         const struct ipt_time_info *info = matchinfo;   /* match info for rule */
  56         struct tm currenttime;                          /* time human readable */
  57         u_int8_t days_of_week[7] = {64, 32, 16, 8, 4, 2, 1};
  58         u_int16_t packet_time;
  59
  60         /* We might not have a timestamp, get one */
  61         if (skb->tstamp.off_sec == 0)
  62                 __net_timestamp((struct sk_buff *)skb);
  63
  64         /* First we make sure we are in the date start-stop boundaries */
  65         if ((skb->tstamp.off_sec < info->date_start) || (skb->tstamp.off_sec > info->date_stop))
  66                 return 0; /* We are outside the date boundaries */
  67
  68         /* Transform the timestamp of the packet, in a human readable form */
  69         localtime(skb->tstamp.off_sec, &currenttime);
  70
  71         /* check if we match this timestamp, we start by the days... */
  72         if ((days_of_week[currenttime.tm_wday] & info->days_match) != days_of_week[currenttime.tm_wday])
  73                 return 0; /* the day doesn't match */
  74
  75         /* ... check the time now */
  76         packet_time = (currenttime.tm_hour * 60) + currenttime.tm_min;
  77         if ((packet_time < info->time_start) || (packet_time > info->time_stop))
  78                 return 0;
  79
  80         /* here we match ! */
  81         return 1;
  82 }
  83
  84 static int
  85 checkentry(const char *tablename,
  86            const void *ip,
  87            const struct xt_match *match,
  88            void *matchinfo,
  89            unsigned int hook_mask)
  90 {
  91         struct ipt_time_info *info = matchinfo;   /* match info for rule */
  92
  93         /* First, check that we are in the correct hooks */
  94         if (hook_mask
  95             & ~((1 << NF_IP_PRE_ROUTING) | (1 << NF_IP_LOCAL_IN) | (1 << NF_IP_FORWARD) | (1 << NF_IP_LOCAL_OUT)))
  96         {
  97                 printk("ipt_time: error, only valid for PRE_ROUTING, LOCAL_IN, FORWARD and OUTPUT)\n");
  98                 return 0;
  99         }
 100
 101         /* Now check the coherence of the data ... */
 102         if ((info->time_start > 1439) ||        /* 23*60+59 = 1439*/
 103             (info->time_stop  > 1439))
 104         {
 105                 printk(KERN_WARNING "ipt_time: invalid argument\n");
 106                 return 0;
 107         }
 108
 109         return 1;
 110 }
 111
 112 static struct ipt_match time_match = {
 113         .name = "time",
 114         .match = &match,
 115         .matchsize = sizeof(struct ipt_time_info),
 116         .checkentry = &checkentry,
 117         .me = THIS_MODULE
 118 };
 119
 120 static int __init init(void)
 121 {
 122         printk("ipt_time loading\n");
 123         return ipt_register_match(&time_match);
 124 }
 125
 126 static void __exit fini(void)
 127 {
 128         ipt_unregister_match(&time_match);
 129         printk("ipt_time unloaded\n");
 130 }
 131
 132 module_init(init);
 133 module_exit(fini);
 134
 135
 136 /* The part below is borowed and modified from dietlibc */
 137
 138 /* seconds per day */
 139 #define SPD 24*60*60
 140
 141 static void
 142 localtime(const u32 time, struct tm *r) {
 143         u32 i, timep;
 144         extern struct timezone sys_tz;
 145         const unsigned int __spm[12] =
 146                 { 0,
 147                   (31),
 148                   (31+28),
 149                   (31+28+31),
 150                   (31+28+31+30),
 151                   (31+28+31+30+31),
 152                   (31+28+31+30+31+30),
 153                   (31+28+31+30+31+30+31),
 154                   (31+28+31+30+31+30+31+31),
 155                   (31+28+31+30+31+30+31+31+30),
 156                   (31+28+31+30+31+30+31+31+30+31),
 157                   (31+28+31+30+31+30+31+31+30+31+30),
 158                 };
 159         register u32 work;
 160
 161         timep = time - (sys_tz.tz_minuteswest * 60);
 162         work=timep%(SPD);
 163         r->tm_sec=work%60; work/=60;
 164         r->tm_min=work%60; r->tm_hour=work/60;
 165         work=timep/(SPD);
 166         r->tm_wday=(4+work)%7;
 167         for (i=1970; ; ++i) {
 168                 register time_t k= (!(i%4) && ((i%100) || !(i%400)))?366:365;
 169                 if (work>k)
 170                         work-=k;
 171                 else
 172                         break;
 173         }
 174         r->tm_year=i-1900;
 175         for (i=11; i && __spm[i]>work; --i) ;
 176         r->tm_mon=i;
 177         r->tm_mday=work-__spm[i]+1;
 178 }