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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * IP tables module for matching the value of the TTL
4 * (C) 2000,2001 by Harald Welte <laforge@netfilter.org>
5 *
6 * Hop Limit matching module
7 * (C) 2001-2002 Maciej Soltysiak <solt@dns.toxicfilms.tv>
8 */
9
10#include <linux/ip.h>
11#include <linux/ipv6.h>
12#include <linux/module.h>
13#include <linux/skbuff.h>
14
15#include <linux/netfilter/x_tables.h>
16#include <linux/netfilter_ipv4/ipt_ttl.h>
17#include <linux/netfilter_ipv6/ip6t_hl.h>
18
19MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
20MODULE_DESCRIPTION("Xtables: Hoplimit/TTL field match");
21MODULE_LICENSE("GPL");
22MODULE_ALIAS("ipt_ttl");
23MODULE_ALIAS("ip6t_hl");
24
25static bool ttl_mt(const struct sk_buff *skb, struct xt_action_param *par)
26{
27 const struct ipt_ttl_info *info = par->matchinfo;
28 const u8 ttl = ip_hdr(skb)->ttl;
29
30 switch (info->mode) {
31 case IPT_TTL_EQ:
32 return ttl == info->ttl;
33 case IPT_TTL_NE:
34 return ttl != info->ttl;
35 case IPT_TTL_LT:
36 return ttl < info->ttl;
37 case IPT_TTL_GT:
38 return ttl > info->ttl;
39 }
40
41 return false;
42}
43
44static bool hl_mt6(const struct sk_buff *skb, struct xt_action_param *par)
45{
46 const struct ip6t_hl_info *info = par->matchinfo;
47 const struct ipv6hdr *ip6h = ipv6_hdr(skb);
48
49 switch (info->mode) {
50 case IP6T_HL_EQ:
51 return ip6h->hop_limit == info->hop_limit;
52 case IP6T_HL_NE:
53 return ip6h->hop_limit != info->hop_limit;
54 case IP6T_HL_LT:
55 return ip6h->hop_limit < info->hop_limit;
56 case IP6T_HL_GT:
57 return ip6h->hop_limit > info->hop_limit;
58 }
59
60 return false;
61}
62
63static struct xt_match hl_mt_reg[] __read_mostly = {
64 {
65 .name = "ttl",
66 .revision = 0,
67 .family = NFPROTO_IPV4,
68 .match = ttl_mt,
69 .matchsize = sizeof(struct ipt_ttl_info),
70 .me = THIS_MODULE,
71 },
72 {
73 .name = "hl",
74 .revision = 0,
75 .family = NFPROTO_IPV6,
76 .match = hl_mt6,
77 .matchsize = sizeof(struct ip6t_hl_info),
78 .me = THIS_MODULE,
79 },
80};
81
82static int __init hl_mt_init(void)
83{
84 return xt_register_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
85}
86
87static void __exit hl_mt_exit(void)
88{
89 xt_unregister_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
90}
91
92module_init(hl_mt_init);
93module_exit(hl_mt_exit);
1/*
2 * IP tables module for matching the value of the TTL
3 * (C) 2000,2001 by Harald Welte <laforge@netfilter.org>
4 *
5 * Hop Limit matching module
6 * (C) 2001-2002 Maciej Soltysiak <solt@dns.toxicfilms.tv>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/ip.h>
14#include <linux/ipv6.h>
15#include <linux/module.h>
16#include <linux/skbuff.h>
17
18#include <linux/netfilter/x_tables.h>
19#include <linux/netfilter_ipv4/ipt_ttl.h>
20#include <linux/netfilter_ipv6/ip6t_hl.h>
21
22MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
23MODULE_DESCRIPTION("Xtables: Hoplimit/TTL field match");
24MODULE_LICENSE("GPL");
25MODULE_ALIAS("ipt_ttl");
26MODULE_ALIAS("ip6t_hl");
27
28static bool ttl_mt(const struct sk_buff *skb, struct xt_action_param *par)
29{
30 const struct ipt_ttl_info *info = par->matchinfo;
31 const u8 ttl = ip_hdr(skb)->ttl;
32
33 switch (info->mode) {
34 case IPT_TTL_EQ:
35 return ttl == info->ttl;
36 case IPT_TTL_NE:
37 return ttl != info->ttl;
38 case IPT_TTL_LT:
39 return ttl < info->ttl;
40 case IPT_TTL_GT:
41 return ttl > info->ttl;
42 }
43
44 return false;
45}
46
47static bool hl_mt6(const struct sk_buff *skb, struct xt_action_param *par)
48{
49 const struct ip6t_hl_info *info = par->matchinfo;
50 const struct ipv6hdr *ip6h = ipv6_hdr(skb);
51
52 switch (info->mode) {
53 case IP6T_HL_EQ:
54 return ip6h->hop_limit == info->hop_limit;
55 case IP6T_HL_NE:
56 return ip6h->hop_limit != info->hop_limit;
57 case IP6T_HL_LT:
58 return ip6h->hop_limit < info->hop_limit;
59 case IP6T_HL_GT:
60 return ip6h->hop_limit > info->hop_limit;
61 }
62
63 return false;
64}
65
66static struct xt_match hl_mt_reg[] __read_mostly = {
67 {
68 .name = "ttl",
69 .revision = 0,
70 .family = NFPROTO_IPV4,
71 .match = ttl_mt,
72 .matchsize = sizeof(struct ipt_ttl_info),
73 .me = THIS_MODULE,
74 },
75 {
76 .name = "hl",
77 .revision = 0,
78 .family = NFPROTO_IPV6,
79 .match = hl_mt6,
80 .matchsize = sizeof(struct ip6t_hl_info),
81 .me = THIS_MODULE,
82 },
83};
84
85static int __init hl_mt_init(void)
86{
87 return xt_register_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
88}
89
90static void __exit hl_mt_exit(void)
91{
92 xt_unregister_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
93}
94
95module_init(hl_mt_init);
96module_exit(hl_mt_exit);