net/netfilter/xt_connbytes.c

   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 #include <net/netfilter/nf_conntrack_acct.h>
  12
  13 MODULE_LICENSE("GPL");
  14 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  15 MODULE_DESCRIPTION("Xtables: Number of packets/bytes per connection matching");
  16 MODULE_ALIAS("ipt_connbytes");
  17 MODULE_ALIAS("ip6t_connbytes");
  18
  19 static bool
  20 connbytes_mt(const struct sk_buff *skb, const struct net_device *in,
  21              const struct net_device *out, const struct xt_match *match,
  22              const void *matchinfo, int offset, unsigned int protoff,
  23              bool *hotdrop)
  24 {
  25         const struct xt_connbytes_info *sinfo = matchinfo;
  26         const struct nf_conn *ct;
  27         enum ip_conntrack_info ctinfo;
  28         u_int64_t what = 0;     /* initialize to make gcc happy */
  29         u_int64_t bytes = 0;
  30         u_int64_t pkts = 0;
  31         const struct nf_conn_counter *counters;
  32
  33         ct = nf_ct_get(skb, &ctinfo);
  34         if (!ct)
  35                 return false;
  36
  37         counters = nf_conn_acct_find(ct);
  38         if (!counters)
  39                 return false;
  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_u64(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 bool
  99 connbytes_mt_check(const char *tablename, const void *ip,
 100                    const struct xt_match *match, void *matchinfo,
 101                    unsigned int hook_mask)
 102 {
 103         const struct xt_connbytes_info *sinfo = matchinfo;
 104
 105         if (sinfo->what != XT_CONNBYTES_PKTS &&
 106             sinfo->what != XT_CONNBYTES_BYTES &&
 107             sinfo->what != XT_CONNBYTES_AVGPKT)
 108                 return false;
 109
 110         if (sinfo->direction != XT_CONNBYTES_DIR_ORIGINAL &&
 111             sinfo->direction != XT_CONNBYTES_DIR_REPLY &&
 112             sinfo->direction != XT_CONNBYTES_DIR_BOTH)
 113                 return false;
 114
 115         if (nf_ct_l3proto_try_module_get(match->family) < 0) {
 116                 printk(KERN_WARNING "can't load conntrack support for "
 117                                     "proto=%u\n", match->family);
 118                 return false;
 119         }
 120
 121         return true;
 122 }
 123
 124 static void
 125 connbytes_mt_destroy(const struct xt_match *match, void *matchinfo)
 126 {
 127         nf_ct_l3proto_module_put(match->family);
 128 }
 129
 130 static struct xt_match connbytes_mt_reg[] __read_mostly = {
 131         {
 132                 .name           = "connbytes",
 133                 .family         = AF_INET,
 134                 .checkentry     = connbytes_mt_check,
 135                 .match          = connbytes_mt,
 136                 .destroy        = connbytes_mt_destroy,
 137                 .matchsize      = sizeof(struct xt_connbytes_info),
 138                 .me             = THIS_MODULE
 139         },
 140         {
 141                 .name           = "connbytes",
 142                 .family         = AF_INET6,
 143                 .checkentry     = connbytes_mt_check,
 144                 .match          = connbytes_mt,
 145                 .destroy        = connbytes_mt_destroy,
 146                 .matchsize      = sizeof(struct xt_connbytes_info),
 147                 .me             = THIS_MODULE
 148         },
 149 };
 150
 151 static int __init connbytes_mt_init(void)
 152 {
 153         return xt_register_matches(connbytes_mt_reg,
 154                ARRAY_SIZE(connbytes_mt_reg));
 155 }
 156
 157 static void __exit connbytes_mt_exit(void)
 158 {
 159         xt_unregister_matches(connbytes_mt_reg, ARRAY_SIZE(connbytes_mt_reg));
 160 }
 161
 162 module_init(connbytes_mt_init);
 163 module_exit(connbytes_mt_exit);