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   1 /* Kernel module to match connection tracking byte counter.
   2  * GPL (C) 2002 Martin Devera (devik@cdi.cz).
   3  */
   4 #include <linux/module.h>
   5 #include <linux/bitops.h>
   6 #include <linux/skbuff.h>
   7 #include <linux/math64.h>
   8 #include <linux/netfilter/x_tables.h>
   9 #include <linux/netfilter/xt_connbytes.h>
  10 #include <net/netfilter/nf_conntrack.h>
  11
  12 MODULE_LICENSE("GPL");
  13 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  14 MODULE_DESCRIPTION("Xtables: Number of packets/bytes per connection matching");
  15 MODULE_ALIAS("ipt_connbytes");
  16 MODULE_ALIAS("ip6t_connbytes");
  17
  18 static bool
  19 connbytes_mt(const struct sk_buff *skb, const struct net_device *in,
  20              const struct net_device *out, const struct xt_match *match,
  21              const void *matchinfo, int offset, unsigned int protoff,
  22              bool *hotdrop)
  23 {
  24         const struct xt_connbytes_info *sinfo = matchinfo;
  25         const struct nf_conn *ct;
  26         enum ip_conntrack_info ctinfo;
  27         u_int64_t what = 0;     /* initialize to make gcc happy */
  28         u_int64_t bytes = 0;
  29         u_int64_t pkts = 0;
  30         const struct ip_conntrack_counter *counters;
  31
  32         ct = nf_ct_get(skb, &ctinfo);
  33         if (!ct)
  34                 return false;
  35         counters = ct->counters;
  36
  37         switch (sinfo->what) {
  38         case XT_CONNBYTES_PKTS:
  39                 switch (sinfo->direction) {
  40                 case XT_CONNBYTES_DIR_ORIGINAL:
  41                         what = counters[IP_CT_DIR_ORIGINAL].packets;
  42                         break;
  43                 case XT_CONNBYTES_DIR_REPLY:
  44                         what = counters[IP_CT_DIR_REPLY].packets;
  45                         break;
  46                 case XT_CONNBYTES_DIR_BOTH:
  47                         what = counters[IP_CT_DIR_ORIGINAL].packets;
  48                         what += counters[IP_CT_DIR_REPLY].packets;
  49                         break;
  50                 }
  51                 break;
  52         case XT_CONNBYTES_BYTES:
  53                 switch (sinfo->direction) {
  54                 case XT_CONNBYTES_DIR_ORIGINAL:
  55                         what = counters[IP_CT_DIR_ORIGINAL].bytes;
  56                         break;
  57                 case XT_CONNBYTES_DIR_REPLY:
  58                         what = counters[IP_CT_DIR_REPLY].bytes;
  59                         break;
  60                 case XT_CONNBYTES_DIR_BOTH:
  61                         what = counters[IP_CT_DIR_ORIGINAL].bytes;
  62                         what += counters[IP_CT_DIR_REPLY].bytes;
  63                         break;
  64                 }
  65                 break;
  66         case XT_CONNBYTES_AVGPKT:
  67                 switch (sinfo->direction) {
  68                 case XT_CONNBYTES_DIR_ORIGINAL:
  69                         bytes = counters[IP_CT_DIR_ORIGINAL].bytes;
  70                         pkts  = counters[IP_CT_DIR_ORIGINAL].packets;
  71                         break;
  72                 case XT_CONNBYTES_DIR_REPLY:
  73                         bytes = counters[IP_CT_DIR_REPLY].bytes;
  74                         pkts  = counters[IP_CT_DIR_REPLY].packets;
  75                         break;
  76                 case XT_CONNBYTES_DIR_BOTH:
  77                         bytes = counters[IP_CT_DIR_ORIGINAL].bytes +
  78                                 counters[IP_CT_DIR_REPLY].bytes;
  79                         pkts  = counters[IP_CT_DIR_ORIGINAL].packets +
  80                                 counters[IP_CT_DIR_REPLY].packets;
  81                         break;
  82                 }
  83                 if (pkts != 0)
  84                         what = div64_u64(bytes, pkts);
  85                 break;
  86         }
  87
  88         if (sinfo->count.to)
  89                 return what <= sinfo->count.to && what >= sinfo->count.from;
  90         else
  91                 return what >= sinfo->count.from;
  92 }
  93
  94 static bool
  95 connbytes_mt_check(const char *tablename, const void *ip,
  96                    const struct xt_match *match, void *matchinfo,
  97                    unsigned int hook_mask)
  98 {
  99         const struct xt_connbytes_info *sinfo = matchinfo;
 100
 101         if (sinfo->what != XT_CONNBYTES_PKTS &&
 102             sinfo->what != XT_CONNBYTES_BYTES &&
 103             sinfo->what != XT_CONNBYTES_AVGPKT)
 104                 return false;
 105
 106         if (sinfo->direction != XT_CONNBYTES_DIR_ORIGINAL &&
 107             sinfo->direction != XT_CONNBYTES_DIR_REPLY &&
 108             sinfo->direction != XT_CONNBYTES_DIR_BOTH)
 109                 return false;
 110
 111         if (nf_ct_l3proto_try_module_get(match->family) < 0) {
 112                 printk(KERN_WARNING "can't load conntrack support for "
 113                                     "proto=%u\n", match->family);
 114                 return false;
 115         }
 116
 117         return true;
 118 }
 119
 120 static void
 121 connbytes_mt_destroy(const struct xt_match *match, void *matchinfo)
 122 {
 123         nf_ct_l3proto_module_put(match->family);
 124 }
 125
 126 static struct xt_match connbytes_mt_reg[] __read_mostly = {
 127         {
 128                 .name           = "connbytes",
 129                 .family         = AF_INET,
 130                 .checkentry     = connbytes_mt_check,
 131                 .match          = connbytes_mt,
 132                 .destroy        = connbytes_mt_destroy,
 133                 .matchsize      = sizeof(struct xt_connbytes_info),
 134                 .me             = THIS_MODULE
 135         },
 136         {
 137                 .name           = "connbytes",
 138                 .family         = AF_INET6,
 139                 .checkentry     = connbytes_mt_check,
 140                 .match          = connbytes_mt,
 141                 .destroy        = connbytes_mt_destroy,
 142                 .matchsize      = sizeof(struct xt_connbytes_info),
 143                 .me             = THIS_MODULE
 144         },
 145 };
 146
 147 static int __init connbytes_mt_init(void)
 148 {
 149         return xt_register_matches(connbytes_mt_reg,
 150                ARRAY_SIZE(connbytes_mt_reg));
 151 }
 152
 153 static void __exit connbytes_mt_exit(void)
 154 {
 155         xt_unregister_matches(connbytes_mt_reg, ARRAY_SIZE(connbytes_mt_reg));
 156 }
 157
 158 module_init(connbytes_mt_init);
 159 module_exit(connbytes_mt_exit);