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/* Kernel module to match connection tracking byte counter.
* GPL (C) 2002 Martin Devera (devik@cdi.cz).
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/skbuff.h>
#include <linux/math64.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_connbytes.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_acct.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_DESCRIPTION("Xtables: Number of packets/bytes per connection matching");
MODULE_ALIAS("ipt_connbytes");
MODULE_ALIAS("ip6t_connbytes");
static bool
connbytes_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct xt_connbytes_info *sinfo = par->matchinfo;
const struct nf_conn *ct;
enum ip_conntrack_info ctinfo;
u_int64_t what = 0; /* initialize to make gcc happy */
u_int64_t bytes = 0;
u_int64_t pkts = 0;
const struct nf_conn_acct *acct;
const struct nf_conn_counter *counters;
ct = nf_ct_get(skb, &ctinfo);
if (!ct)
return false;
acct = nf_conn_acct_find(ct);
if (!acct)
return false;
counters = acct->counter;
switch (sinfo->what) {
case XT_CONNBYTES_PKTS:
switch (sinfo->direction) {
case XT_CONNBYTES_DIR_ORIGINAL:
what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets);
break;
case XT_CONNBYTES_DIR_REPLY:
what = atomic64_read(&counters[IP_CT_DIR_REPLY].packets);
break;
case XT_CONNBYTES_DIR_BOTH:
what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets);
what += atomic64_read(&counters[IP_CT_DIR_REPLY].packets);
break;
}
break;
case XT_CONNBYTES_BYTES:
switch (sinfo->direction) {
case XT_CONNBYTES_DIR_ORIGINAL:
what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes);
break;
case XT_CONNBYTES_DIR_REPLY:
what = atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);
break;
case XT_CONNBYTES_DIR_BOTH:
what = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes);
what += atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);
break;
}
break;
case XT_CONNBYTES_AVGPKT:
switch (sinfo->direction) {
case XT_CONNBYTES_DIR_ORIGINAL:
bytes = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes);
pkts = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets);
break;
case XT_CONNBYTES_DIR_REPLY:
bytes = atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);
pkts = atomic64_read(&counters[IP_CT_DIR_REPLY].packets);
break;
case XT_CONNBYTES_DIR_BOTH:
bytes = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].bytes) +
atomic64_read(&counters[IP_CT_DIR_REPLY].bytes);
pkts = atomic64_read(&counters[IP_CT_DIR_ORIGINAL].packets) +
atomic64_read(&counters[IP_CT_DIR_REPLY].packets);
break;
}
if (pkts != 0)
what = div64_u64(bytes, pkts);
break;
}
if (sinfo->count.to >= sinfo->count.from)
return what <= sinfo->count.to && what >= sinfo->count.from;
else /* inverted */
return what < sinfo->count.to || what > sinfo->count.from;
}
static int connbytes_mt_check(const struct xt_mtchk_param *par)
{
const struct xt_connbytes_info *sinfo = par->matchinfo;
int ret;
if (sinfo->what != XT_CONNBYTES_PKTS &&
sinfo->what != XT_CONNBYTES_BYTES &&
sinfo->what != XT_CONNBYTES_AVGPKT)
return -EINVAL;
if (sinfo->direction != XT_CONNBYTES_DIR_ORIGINAL &&
sinfo->direction != XT_CONNBYTES_DIR_REPLY &&
sinfo->direction != XT_CONNBYTES_DIR_BOTH)
return -EINVAL;
ret = nf_ct_netns_get(par->net, par->family);
if (ret < 0) {
pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
par->family);
return ret;
}
/*
* This filter cannot function correctly unless connection tracking
* accounting is enabled, so complain in the hope that someone notices.
*/
if (!nf_ct_acct_enabled(par->net)) {
pr_warn("Forcing CT accounting to be enabled\n");
nf_ct_set_acct(par->net, true);
}
return ret;
}
static void connbytes_mt_destroy(const struct xt_mtdtor_param *par)
{
nf_ct_netns_put(par->net, par->family);
}
static struct xt_match connbytes_mt_reg __read_mostly = {
.name = "connbytes",
.revision = 0,
.family = NFPROTO_UNSPEC,
.checkentry = connbytes_mt_check,
.match = connbytes_mt,
.destroy = connbytes_mt_destroy,
.matchsize = sizeof(struct xt_connbytes_info),
.me = THIS_MODULE,
};
static int __init connbytes_mt_init(void)
{
return xt_register_match(&connbytes_mt_reg);
}
static void __exit connbytes_mt_exit(void)
{
xt_unregister_match(&connbytes_mt_reg);
}
module_init(connbytes_mt_init);
module_exit(connbytes_mt_exit);
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