Contributors: 9
Author Tokens Token Proportion Commits Commit Proportion
Harald Welte 212 44.44% 1 5.26%
Jan Engelhardt 91 19.08% 8 42.11%
Marino Dzalto 86 18.03% 1 5.26%
Linus Torvalds 42 8.81% 1 5.26%
Art Haas 22 4.61% 2 10.53%
Arnaldo Carvalho de Melo 12 2.52% 2 10.53%
Patrick McHardy 7 1.47% 2 10.53%
Linus Torvalds (pre-git) 3 0.63% 1 5.26%
Thomas Gleixner 2 0.42% 1 5.26%
Total 477 19


// 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>
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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 int ttl_mt_check(const struct xt_mtchk_param *par)
{
	const struct ipt_ttl_info *info = par->matchinfo;

	if (info->mode > IPT_TTL_GT) {
		pr_err("Unknown TTL match mode: %d\n", info->mode);
		return -EINVAL;
	}

	return 0;
}

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 int hl_mt6_check(const struct xt_mtchk_param *par)
{
	const struct ip6t_hl_info *info = par->matchinfo;

	if (info->mode > IP6T_HL_GT) {
		pr_err("Unknown Hop Limit match mode: %d\n", info->mode);
		return -EINVAL;
	}

	return 0;
}

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,
		.checkentry = ttl_mt_check,
		.match      = ttl_mt,
		.matchsize  = sizeof(struct ipt_ttl_info),
		.me         = THIS_MODULE,
	},
	{
		.name       = "hl",
		.revision   = 0,
		.family     = NFPROTO_IPV6,
		.checkentry = hl_mt6_check,
		.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);