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// SPDX-License-Identifier: GPL-2.0-only
/*
* IP tables module for matching the value of the TTL
* (C) 2000,2001 by Harald Welte <laforge@netfilter.org>
*
* Hop Limit matching module
* (C) 2001-2002 Maciej Soltysiak <solt@dns.toxicfilms.tv>
*/
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv4/ipt_ttl.h>
#include <linux/netfilter_ipv6/ip6t_hl.h>
MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
MODULE_DESCRIPTION("Xtables: Hoplimit/TTL field match");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ipt_ttl");
MODULE_ALIAS("ip6t_hl");
static bool ttl_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct ipt_ttl_info *info = par->matchinfo;
const u8 ttl = ip_hdr(skb)->ttl;
switch (info->mode) {
case IPT_TTL_EQ:
return ttl == info->ttl;
case IPT_TTL_NE:
return ttl != info->ttl;
case IPT_TTL_LT:
return ttl < info->ttl;
case IPT_TTL_GT:
return ttl > info->ttl;
}
return false;
}
static bool hl_mt6(const struct sk_buff *skb, struct xt_action_param *par)
{
const struct ip6t_hl_info *info = par->matchinfo;
const struct ipv6hdr *ip6h = ipv6_hdr(skb);
switch (info->mode) {
case IP6T_HL_EQ:
return ip6h->hop_limit == info->hop_limit;
case IP6T_HL_NE:
return ip6h->hop_limit != info->hop_limit;
case IP6T_HL_LT:
return ip6h->hop_limit < info->hop_limit;
case IP6T_HL_GT:
return ip6h->hop_limit > info->hop_limit;
}
return false;
}
static struct xt_match hl_mt_reg[] __read_mostly = {
{
.name = "ttl",
.revision = 0,
.family = NFPROTO_IPV4,
.match = ttl_mt,
.matchsize = sizeof(struct ipt_ttl_info),
.me = THIS_MODULE,
},
{
.name = "hl",
.revision = 0,
.family = NFPROTO_IPV6,
.match = hl_mt6,
.matchsize = sizeof(struct ip6t_hl_info),
.me = THIS_MODULE,
},
};
static int __init hl_mt_init(void)
{
return xt_register_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
}
static void __exit hl_mt_exit(void)
{
xt_unregister_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
}
module_init(hl_mt_init);
module_exit(hl_mt_exit);
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