// SPDX-License-Identifier: GPL-2.0-only
|
/* Kernel module to match packet length. */
|
/* (C) 1999-2001 James Morris <jmorros@intercode.com.au>
|
*/
|
|
#include <linux/module.h>
|
#include <linux/skbuff.h>
|
#include <linux/ipv6.h>
|
#include <net/ip.h>
|
|
#include <linux/netfilter/xt_length.h>
|
#include <linux/netfilter/x_tables.h>
|
|
MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
|
MODULE_DESCRIPTION("Xtables: Packet length (Layer3,4,5) match");
|
MODULE_LICENSE("GPL");
|
MODULE_ALIAS("ipt_length");
|
MODULE_ALIAS("ip6t_length");
|
|
static bool
|
length_mt(const struct sk_buff *skb, struct xt_action_param *par)
|
{
|
const struct xt_length_info *info = par->matchinfo;
|
u_int16_t pktlen = ntohs(ip_hdr(skb)->tot_len);
|
|
return (pktlen >= info->min && pktlen <= info->max) ^ info->invert;
|
}
|
|
static bool
|
length_mt6(const struct sk_buff *skb, struct xt_action_param *par)
|
{
|
const struct xt_length_info *info = par->matchinfo;
|
const u_int16_t pktlen = ntohs(ipv6_hdr(skb)->payload_len) +
|
sizeof(struct ipv6hdr);
|
|
return (pktlen >= info->min && pktlen <= info->max) ^ info->invert;
|
}
|
|
static struct xt_match length_mt_reg[] __read_mostly = {
|
{
|
.name = "length",
|
.family = NFPROTO_IPV4,
|
.match = length_mt,
|
.matchsize = sizeof(struct xt_length_info),
|
.me = THIS_MODULE,
|
},
|
{
|
.name = "length",
|
.family = NFPROTO_IPV6,
|
.match = length_mt6,
|
.matchsize = sizeof(struct xt_length_info),
|
.me = THIS_MODULE,
|
},
|
};
|
|
static int __init length_mt_init(void)
|
{
|
return xt_register_matches(length_mt_reg, ARRAY_SIZE(length_mt_reg));
|
}
|
|
static void __exit length_mt_exit(void)
|
{
|
xt_unregister_matches(length_mt_reg, ARRAY_SIZE(length_mt_reg));
|
}
|
|
module_init(length_mt_init);
|
module_exit(length_mt_exit);
|
