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xt_connbytes.c
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xt_connbytes.c
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/* Kernel module to match connection tracking byte counter.
* GPL (C) 2002 Martin Devera ([email protected]).
*/
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/skbuff.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_connbytes.h>
#include <net/netfilter/nf_conntrack.h>
#include <asm/div64.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <[email protected]>");
MODULE_DESCRIPTION("iptables match for matching number of pkts/bytes per connection");
MODULE_ALIAS("ipt_connbytes");
MODULE_ALIAS("ip6t_connbytes");
static bool
connbytes_mt(const struct sk_buff *skb, const struct net_device *in,
const struct net_device *out, const struct xt_match *match,
const void *matchinfo, int offset, unsigned int protoff,
bool *hotdrop)
{
const struct xt_connbytes_info *sinfo = 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 ip_conntrack_counter *counters;
ct = nf_ct_get(skb, &ctinfo);
if (!ct)
return false;
counters = ct->counters;
switch (sinfo->what) {
case XT_CONNBYTES_PKTS:
switch (sinfo->direction) {
case XT_CONNBYTES_DIR_ORIGINAL:
what = counters[IP_CT_DIR_ORIGINAL].packets;
break;
case XT_CONNBYTES_DIR_REPLY:
what = counters[IP_CT_DIR_REPLY].packets;
break;
case XT_CONNBYTES_DIR_BOTH:
what = counters[IP_CT_DIR_ORIGINAL].packets;
what += counters[IP_CT_DIR_REPLY].packets;
break;
}
break;
case XT_CONNBYTES_BYTES:
switch (sinfo->direction) {
case XT_CONNBYTES_DIR_ORIGINAL:
what = counters[IP_CT_DIR_ORIGINAL].bytes;
break;
case XT_CONNBYTES_DIR_REPLY:
what = counters[IP_CT_DIR_REPLY].bytes;
break;
case XT_CONNBYTES_DIR_BOTH:
what = counters[IP_CT_DIR_ORIGINAL].bytes;
what += counters[IP_CT_DIR_REPLY].bytes;
break;
}
break;
case XT_CONNBYTES_AVGPKT:
switch (sinfo->direction) {
case XT_CONNBYTES_DIR_ORIGINAL:
bytes = counters[IP_CT_DIR_ORIGINAL].bytes;
pkts = counters[IP_CT_DIR_ORIGINAL].packets;
break;
case XT_CONNBYTES_DIR_REPLY:
bytes = counters[IP_CT_DIR_REPLY].bytes;
pkts = counters[IP_CT_DIR_REPLY].packets;
break;
case XT_CONNBYTES_DIR_BOTH:
bytes = counters[IP_CT_DIR_ORIGINAL].bytes +
counters[IP_CT_DIR_REPLY].bytes;
pkts = counters[IP_CT_DIR_ORIGINAL].packets +
counters[IP_CT_DIR_REPLY].packets;
break;
}
if (pkts != 0)
what = div64_64(bytes, pkts);
break;
}
if (sinfo->count.to)
return what <= sinfo->count.to && what >= sinfo->count.from;
else
return what >= sinfo->count.from;
}
static bool
connbytes_mt_check(const char *tablename, const void *ip,
const struct xt_match *match, void *matchinfo,
unsigned int hook_mask)
{
const struct xt_connbytes_info *sinfo = matchinfo;
if (sinfo->what != XT_CONNBYTES_PKTS &&
sinfo->what != XT_CONNBYTES_BYTES &&
sinfo->what != XT_CONNBYTES_AVGPKT)
return false;
if (sinfo->direction != XT_CONNBYTES_DIR_ORIGINAL &&
sinfo->direction != XT_CONNBYTES_DIR_REPLY &&
sinfo->direction != XT_CONNBYTES_DIR_BOTH)
return false;
if (nf_ct_l3proto_try_module_get(match->family) < 0) {
printk(KERN_WARNING "can't load conntrack support for "
"proto=%u\n", match->family);
return false;
}
return true;
}
static void
connbytes_mt_destroy(const struct xt_match *match, void *matchinfo)
{
nf_ct_l3proto_module_put(match->family);
}
static struct xt_match connbytes_mt_reg[] __read_mostly = {
{
.name = "connbytes",
.family = AF_INET,
.checkentry = connbytes_mt_check,
.match = connbytes_mt,
.destroy = connbytes_mt_destroy,
.matchsize = sizeof(struct xt_connbytes_info),
.me = THIS_MODULE
},
{
.name = "connbytes",
.family = AF_INET6,
.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_matches(connbytes_mt_reg,
ARRAY_SIZE(connbytes_mt_reg));
}
static void __exit connbytes_mt_exit(void)
{
xt_unregister_matches(connbytes_mt_reg, ARRAY_SIZE(connbytes_mt_reg));
}
module_init(connbytes_mt_init);
module_exit(connbytes_mt_exit);