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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/skbuff.h>
   6 #include <linux/netfilter/x_tables.h>
   7 #include <linux/netfilter/xt_connbytes.h>
   8 #include <net/netfilter/nf_conntrack.h>
   9
  10 #include <asm/div64.h>
  11 #include <asm/bitops.h>
  12
  13 MODULE_LICENSE("GPL");
  14 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  15 MODULE_DESCRIPTION("iptables match for matching number of pkts/bytes per connection");
  16 MODULE_ALIAS("ipt_connbytes");
  17
  18 static int
  19 match(const struct sk_buff *skb,
  20       const struct net_device *in,
  21       const struct net_device *out,
  22       const struct xt_match *match,
  23       const void *matchinfo,
  24       int offset,
  25       unsigned int protoff,
  26       bool *hotdrop)
  27 {
  28         const struct xt_connbytes_info *sinfo = matchinfo;
  29         struct nf_conn *ct;
  30         enum ip_conntrack_info ctinfo;
  31         u_int64_t what = 0;     /* initialize to make gcc happy */
  32         u_int64_t bytes = 0;
  33         u_int64_t pkts = 0;
  34         const struct ip_conntrack_counter *counters;
  35
  36         ct = nf_ct_get(skb, &ctinfo);
  37         if (!ct)
  38                 return 0;
  39         counters = ct->counters;
  40
  41         switch (sinfo->what) {
  42         case XT_CONNBYTES_PKTS:
  43                 switch (sinfo->direction) {
  44                 case XT_CONNBYTES_DIR_ORIGINAL:
  45                         what = counters[IP_CT_DIR_ORIGINAL].packets;
  46                         break;
  47                 case XT_CONNBYTES_DIR_REPLY:
  48                         what = counters[IP_CT_DIR_REPLY].packets;
  49                         break;
  50                 case XT_CONNBYTES_DIR_BOTH:
  51                         what = counters[IP_CT_DIR_ORIGINAL].packets;
  52                         what += counters[IP_CT_DIR_REPLY].packets;
  53                         break;
  54                 }
  55                 break;
  56         case XT_CONNBYTES_BYTES:
  57                 switch (sinfo->direction) {
  58                 case XT_CONNBYTES_DIR_ORIGINAL:
  59                         what = counters[IP_CT_DIR_ORIGINAL].bytes;
  60                         break;
  61                 case XT_CONNBYTES_DIR_REPLY:
  62                         what = counters[IP_CT_DIR_REPLY].bytes;
  63                         break;
  64                 case XT_CONNBYTES_DIR_BOTH:
  65                         what = counters[IP_CT_DIR_ORIGINAL].bytes;
  66                         what += counters[IP_CT_DIR_REPLY].bytes;
  67                         break;
  68                 }
  69                 break;
  70         case XT_CONNBYTES_AVGPKT:
  71                 switch (sinfo->direction) {
  72                 case XT_CONNBYTES_DIR_ORIGINAL:
  73                         bytes = counters[IP_CT_DIR_ORIGINAL].bytes;
  74                         pkts  = counters[IP_CT_DIR_ORIGINAL].packets;
  75                         break;
  76                 case XT_CONNBYTES_DIR_REPLY:
  77                         bytes = counters[IP_CT_DIR_REPLY].bytes;
  78                         pkts  = counters[IP_CT_DIR_REPLY].packets;
  79                         break;
  80                 case XT_CONNBYTES_DIR_BOTH:
  81                         bytes = counters[IP_CT_DIR_ORIGINAL].bytes +
  82                                 counters[IP_CT_DIR_REPLY].bytes;
  83                         pkts  = counters[IP_CT_DIR_ORIGINAL].packets +
  84                                 counters[IP_CT_DIR_REPLY].packets;
  85                         break;
  86                 }
  87                 if (pkts != 0)
  88                         what = div64_64(bytes, pkts);
  89                 break;
  90         }
  91
  92         if (sinfo->count.to)
  93                 return (what <= sinfo->count.to && what >= sinfo->count.from);
  94         else
  95                 return (what >= sinfo->count.from);
  96 }
  97
  98 static int check(const char *tablename,
  99                  const void *ip,
 100                  const struct xt_match *match,
 101                  void *matchinfo,
 102                  unsigned int hook_mask)
 103 {
 104         const struct xt_connbytes_info *sinfo = matchinfo;
 105
 106         if (sinfo->what != XT_CONNBYTES_PKTS &&
 107             sinfo->what != XT_CONNBYTES_BYTES &&
 108             sinfo->what != XT_CONNBYTES_AVGPKT)
 109                 return 0;
 110
 111         if (sinfo->direction != XT_CONNBYTES_DIR_ORIGINAL &&
 112             sinfo->direction != XT_CONNBYTES_DIR_REPLY &&
 113             sinfo->direction != XT_CONNBYTES_DIR_BOTH)
 114                 return 0;
 115
 116         if (nf_ct_l3proto_try_module_get(match->family) < 0) {
 117                 printk(KERN_WARNING "can't load conntrack support for "
 118                                     "proto=%d\n", match->family);
 119                 return 0;
 120         }
 121
 122         return 1;
 123 }
 124
 125 static void
 126 destroy(const struct xt_match *match, void *matchinfo)
 127 {
 128         nf_ct_l3proto_module_put(match->family);
 129 }
 130
 131 static struct xt_match xt_connbytes_match[] = {
 132         {
 133                 .name           = "connbytes",
 134                 .family         = AF_INET,
 135                 .checkentry     = check,
 136                 .match          = match,
 137                 .destroy        = destroy,
 138                 .matchsize      = sizeof(struct xt_connbytes_info),
 139                 .me             = THIS_MODULE
 140         },
 141         {
 142                 .name           = "connbytes",
 143                 .family         = AF_INET6,
 144                 .checkentry     = check,
 145                 .match          = match,
 146                 .destroy        = destroy,
 147                 .matchsize      = sizeof(struct xt_connbytes_info),
 148                 .me             = THIS_MODULE
 149         },
 150 };
 151
 152 static int __init xt_connbytes_init(void)
 153 {
 154         return xt_register_matches(xt_connbytes_match,
 155                                    ARRAY_SIZE(xt_connbytes_match));
 156 }
 157
 158 static void __exit xt_connbytes_fini(void)
 159 {
 160         xt_unregister_matches(xt_connbytes_match,
 161                               ARRAY_SIZE(xt_connbytes_match));
 162 }
 163
 164 module_init(xt_connbytes_init);
 165 module_exit(xt_connbytes_fini);