| Jan Engelhardt | cfac5ef | 2009-02-18 18:39:31 +0100 | [diff] [blame] | 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 | |
| 22 | MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>"); |
| 23 | MODULE_DESCRIPTION("Xtables: Hoplimit/TTL field match"); |
| 24 | MODULE_LICENSE("GPL"); |
| 25 | MODULE_ALIAS("ipt_ttl"); |
| 26 | MODULE_ALIAS("ip6t_hl"); |
| 27 | |
| 28 | static 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 | |
| 51 | static 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 | |
| 78 | static 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 | |
| 97 | static int __init hl_mt_init(void) |
| 98 | { |
| 99 | return xt_register_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg)); |
| 100 | } |
| 101 | |
| 102 | static void __exit hl_mt_exit(void) |
| 103 | { |
| 104 | xt_unregister_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg)); |
| 105 | } |
| 106 | |
| 107 | module_init(hl_mt_init); |
| 108 | module_exit(hl_mt_exit); |