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