tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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, const struct xt_match_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 default:
43 printk(KERN_WARNING "ipt_ttl: unknown mode %d\n",
44 info->mode);
45 return false;
46 }
47
48 return false;
49}
50
51static bool hl_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
52{
53 const struct ip6t_hl_info *info = par->matchinfo;
54 const struct ipv6hdr *ip6h = ipv6_hdr(skb);
55
56 switch (info->mode) {
57 case IP6T_HL_EQ:
58 return ip6h->hop_limit == info->hop_limit;
59 break;
60 case IP6T_HL_NE:
61 return ip6h->hop_limit != info->hop_limit;
62 break;
63 case IP6T_HL_LT:
64 return ip6h->hop_limit < info->hop_limit;
65 break;
66 case IP6T_HL_GT:
67 return ip6h->hop_limit > info->hop_limit;
68 break;
69 default:
70 printk(KERN_WARNING "ip6t_hl: unknown mode %d\n",
71 info->mode);
72 return false;
73 }
74
75 return false;
76}
77
78static struct xt_match hl_mt_reg[] __read_mostly = {
79 {
80 .name = "ttl",
81 .revision = 0,
82 .family = NFPROTO_IPV4,
83 .match = ttl_mt,
84 .matchsize = sizeof(struct ipt_ttl_info),
85 .me = THIS_MODULE,
86 },
87 {
88 .name = "hl",
89 .revision = 0,
90 .family = NFPROTO_IPV6,
91 .match = hl_mt6,
92 .matchsize = sizeof(struct ip6t_hl_info),
93 .me = THIS_MODULE,
94 },
95};
96
97static int __init hl_mt_init(void)
98{
99 return xt_register_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
100}
101
102static void __exit hl_mt_exit(void)
103{
104 xt_unregister_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
105}
106
107module_init(hl_mt_init);
108module_exit(hl_mt_exit);