linux/net/netfilter/xt_connbytes.c
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   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
  14MODULE_LICENSE("GPL");
  15MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
  16MODULE_DESCRIPTION("Xtables: Number of packets/bytes per connection matching");
  17MODULE_ALIAS("ipt_connbytes");
  18MODULE_ALIAS("ip6t_connbytes");
  19
  20static bool
  21connbytes_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_acct *acct;
  30        const struct nf_conn_counter *counters;
  31
  32        ct = nf_ct_get(skb, &ctinfo);
  33        if (!ct)
  34                return false;
  35
  36        acct = nf_conn_acct_find(ct);
  37        if (!acct)
  38                return false;
  39
  40        counters = acct->counter;
  41        switch (sinfo->what) {
  42        case XT_CONNBYTES_PKTS:
  43                switch (sinfo->direction) {
  44                case XT_CONNBYTES_DIR_ORIGINAL:
  45                        what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets);
  46                        break;
  47                case XT_CONNBYTES_DIR_REPLY:
  48                        what = atomic64_read(&counters[IP_CT_DIR_REPLY].packets);
  49                        break;
  50                case XT_CONNBYTES_DIR_BOTH:
  51                        what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets);
  52                        what += atomic64_read(&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 = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes);
  60                        break;
  61                case XT_CONNBYTES_DIR_REPLY:
  62                        what = atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);
  63                        break;
  64                case XT_CONNBYTES_DIR_BOTH:
  65                        what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes);
  66                        what += atomic64_read(&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 = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes);
  74                        pkts  = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets);
  75                        break;
  76                case XT_CONNBYTES_DIR_REPLY:
  77                        bytes = atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);
  78                        pkts  = atomic64_read(&counters[IP_CT_DIR_REPLY].packets);
  79                        break;
  80                case XT_CONNBYTES_DIR_BOTH:
  81                        bytes = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes) +
  82                                atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);
  83                        pkts  = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets) +
  84                                atomic64_read(&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 >= sinfo->count.from)
  93                return what <= sinfo->count.to && what >= sinfo->count.from;
  94        else /* inverted */
  95                return what < sinfo->count.to || what > sinfo->count.from;
  96}
  97
  98static int connbytes_mt_check(const struct xt_mtchk_param *par)
  99{
 100        const struct xt_connbytes_info *sinfo = par->matchinfo;
 101        int ret;
 102
 103        if (sinfo->what != XT_CONNBYTES_PKTS &&
 104            sinfo->what != XT_CONNBYTES_BYTES &&
 105            sinfo->what != XT_CONNBYTES_AVGPKT)
 106                return -EINVAL;
 107
 108        if (sinfo->direction != XT_CONNBYTES_DIR_ORIGINAL &&
 109            sinfo->direction != XT_CONNBYTES_DIR_REPLY &&
 110            sinfo->direction != XT_CONNBYTES_DIR_BOTH)
 111                return -EINVAL;
 112
 113        ret = nf_ct_l3proto_try_module_get(par->family);
 114        if (ret < 0)
 115                pr_info("cannot load conntrack support for proto=%u\n",
 116                        par->family);
 117
 118        /*
 119         * This filter cannot function correctly unless connection tracking
 120         * accounting is enabled, so complain in the hope that someone notices.
 121         */
 122        if (!nf_ct_acct_enabled(par->net)) {
 123                pr_warn("Forcing CT accounting to be enabled\n");
 124                nf_ct_set_acct(par->net, true);
 125        }
 126
 127        return ret;
 128}
 129
 130static void connbytes_mt_destroy(const struct xt_mtdtor_param *par)
 131{
 132        nf_ct_l3proto_module_put(par->family);
 133}
 134
 135static struct xt_match connbytes_mt_reg __read_mostly = {
 136        .name       = "connbytes",
 137        .revision   = 0,
 138        .family     = NFPROTO_UNSPEC,
 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
 146static int __init connbytes_mt_init(void)
 147{
 148        return xt_register_match(&connbytes_mt_reg);
 149}
 150
 151static void __exit connbytes_mt_exit(void)
 152{
 153        xt_unregister_match(&connbytes_mt_reg);
 154}
 155
 156module_init(connbytes_mt_init);
 157module_exit(connbytes_mt_exit);
 158