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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   5 #include <linux/module.h>
   6 #include <linux/bitops.h>
   7 #include <linux/skbuff.h>
   8 #include <linux/math64.h>
   9 #include <linux/netfilter/x_tables.h>
  10 #include <linux/netfilter/xt_connbytes.h>
  11 #include <net/netfilter/nf_conntrack.h>
  12 #include <net/netfilter/nf_conntrack_acct.h>
  13
  14 MODULE_LICENSE("GPL");
  15 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  16 MODULE_DESCRIPTION("Xtables: Number of packets/bytes per connection matching");
  17 MODULE_ALIAS("ipt_connbytes");
  18 MODULE_ALIAS("ip6t_connbytes");
  19
  20 static bool
  21 connbytes_mt(const struct sk_buff *skb, struct xt_action_param *par)
  22 {
  23         const struct xt_connbytes_info *sinfo = par->matchinfo;
  24         const struct nf_conn *ct;
  25         enum ip_conntrack_info ctinfo;
  26         u_int64_t what = 0;     /* initialize to make gcc happy */
  27         u_int64_t bytes = 0;
  28         u_int64_t pkts = 0;
  29         const struct nf_conn_counter *counters;
  30
  31         ct = nf_ct_get(skb, &ctinfo);
  32         if (!ct)
  33                 return false;
  34
  35         counters = nf_conn_acct_find(ct);
  36         if (!counters)
  37                 return false;
  38
  39         switch (sinfo->what) {
  40         case XT_CONNBYTES_PKTS:
  41                 switch (sinfo->direction) {
  42                 case XT_CONNBYTES_DIR_ORIGINAL:
  43                         what = counters[IP_CT_DIR_ORIGINAL].packets;
  44                         break;
  45                 case XT_CONNBYTES_DIR_REPLY:
  46                         what = counters[IP_CT_DIR_REPLY].packets;
  47                         break;
  48                 case XT_CONNBYTES_DIR_BOTH:
  49                         what = counters[IP_CT_DIR_ORIGINAL].packets;
  50                         what += counters[IP_CT_DIR_REPLY].packets;
  51                         break;
  52                 }
  53                 break;
  54         case XT_CONNBYTES_BYTES:
  55                 switch (sinfo->direction) {
  56                 case XT_CONNBYTES_DIR_ORIGINAL:
  57                         what = counters[IP_CT_DIR_ORIGINAL].bytes;
  58                         break;
  59                 case XT_CONNBYTES_DIR_REPLY:
  60                         what = counters[IP_CT_DIR_REPLY].bytes;
  61                         break;
  62                 case XT_CONNBYTES_DIR_BOTH:
  63                         what = counters[IP_CT_DIR_ORIGINAL].bytes;
  64                         what += counters[IP_CT_DIR_REPLY].bytes;
  65                         break;
  66                 }
  67                 break;
  68         case XT_CONNBYTES_AVGPKT:
  69                 switch (sinfo->direction) {
  70                 case XT_CONNBYTES_DIR_ORIGINAL:
  71                         bytes = counters[IP_CT_DIR_ORIGINAL].bytes;
  72                         pkts  = counters[IP_CT_DIR_ORIGINAL].packets;
  73                         break;
  74                 case XT_CONNBYTES_DIR_REPLY:
  75                         bytes = counters[IP_CT_DIR_REPLY].bytes;
  76                         pkts  = counters[IP_CT_DIR_REPLY].packets;
  77                         break;
  78                 case XT_CONNBYTES_DIR_BOTH:
  79                         bytes = counters[IP_CT_DIR_ORIGINAL].bytes +
  80                                 counters[IP_CT_DIR_REPLY].bytes;
  81                         pkts  = counters[IP_CT_DIR_ORIGINAL].packets +
  82                                 counters[IP_CT_DIR_REPLY].packets;
  83                         break;
  84                 }
  85                 if (pkts != 0)
  86                         what = div64_u64(bytes, pkts);
  87                 break;
  88         }
  89
  90         if (sinfo->count.to)
  91                 return what <= sinfo->count.to && what >= sinfo->count.from;
  92         else
  93                 return what >= sinfo->count.from;
  94 }
  95
  96 static int connbytes_mt_check(const struct xt_mtchk_param *par)
  97 {
  98         const struct xt_connbytes_info *sinfo = par->matchinfo;
  99         int ret;
 100
 101         if (sinfo->what != XT_CONNBYTES_PKTS &&
 102             sinfo->what != XT_CONNBYTES_BYTES &&
 103             sinfo->what != XT_CONNBYTES_AVGPKT)
 104                 return -EINVAL;
 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 -EINVAL;
 110
 111         ret = nf_ct_l3proto_try_module_get(par->family);
 112         if (ret < 0)
 113                 pr_info("cannot load conntrack support for proto=%u\n",
 114                         par->family);
 115
 116         /*
 117          * This filter cannot function correctly unless connection tracking
 118          * accounting is enabled, so complain in the hope that someone notices.
 119          */
 120         if (!nf_ct_acct_enabled(par->net)) {
 121                 pr_warning("Forcing CT accounting to be enabled\n");
 122                 nf_ct_set_acct(par->net, true);
 123         }
 124
 125         return ret;
 126 }
 127
 128 static void connbytes_mt_destroy(const struct xt_mtdtor_param *par)
 129 {
 130         nf_ct_l3proto_module_put(par->family);
 131 }
 132
 133 static struct xt_match connbytes_mt_reg __read_mostly = {
 134         .name       = "connbytes",
 135         .revision   = 0,
 136         .family     = NFPROTO_UNSPEC,
 137         .checkentry = connbytes_mt_check,
 138         .match      = connbytes_mt,
 139         .destroy    = connbytes_mt_destroy,
 140         .matchsize  = sizeof(struct xt_connbytes_info),
 141         .me         = THIS_MODULE,
 142 };
 143
 144 static int __init connbytes_mt_init(void)
 145 {
 146         return xt_register_match(&connbytes_mt_reg);
 147 }
 148
 149 static void __exit connbytes_mt_exit(void)
 150 {
 151         xt_unregister_match(&connbytes_mt_reg);
 152 }
 153
 154 module_init(connbytes_mt_init);
 155 module_exit(connbytes_mt_exit);