| 1 | |
| 2 | |
| 3 | * IP tables module for matching the value of the TTL
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| 4 | * (C) 2000,2001 by Harald Welte <[email protected]>
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| 5 | *
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| 6 | * Hop Limit matching module
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| 7 | * (C) 2001-2002 Maciej Soltysiak <[email protected]>
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| 8 |
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| 9 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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| 10 |
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| 11 | #include <linux/ip.h>
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| 12 | #include <linux/ipv6.h>
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| 13 | #include <linux/module.h>
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| 14 | #include <linux/skbuff.h>
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| 15 |
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| 16 | #include <linux/netfilter/x_tables.h>
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| 17 | #include <linux/netfilter_ipv4/ipt_ttl.h>
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| 18 | #include <linux/netfilter_ipv6/ip6t_hl.h>
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| 19 |
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| 20 | MODULE_AUTHOR("Maciej Soltysiak <[email protected]>");
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| 21 | MODULE_DESCRIPTION("Xtables: Hoplimit/TTL field match");
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| 22 | MODULE_LICENSE("GPL");
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| 23 | MODULE_ALIAS("ipt_ttl");
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| 24 | MODULE_ALIAS("ip6t_hl");
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| 25 |
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| 26 | static int ttl_mt_check(const struct xt_mtchk_param *par)
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| 27 | {
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| 28 | const struct ipt_ttl_info *info = par->matchinfo;
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| 29 |
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| 30 | if (info->mode > IPT_TTL_GT) {
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| 31 | pr_info_ratelimited("Unknown TTL match mode: %d\n", info->mode);
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| 32 | return -EINVAL;
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| 33 | }
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| 34 |
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| 35 | return 0;
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| 36 | }
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| 37 |
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| 38 | static bool ttl_mt(const struct sk_buff *skb, struct xt_action_param *par)
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| 39 | {
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| 40 | const struct ipt_ttl_info *info = par->matchinfo;
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| 41 | const u8 ttl = ip_hdr(skb)->ttl;
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| 42 |
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| 43 | switch (info->mode) {
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| 44 | case IPT_TTL_EQ:
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| 45 | return ttl == info->ttl;
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| 46 | case IPT_TTL_NE:
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| 47 | return ttl != info->ttl;
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| 48 | case IPT_TTL_LT:
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| 49 | return ttl < info->ttl;
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| 50 | case IPT_TTL_GT:
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| 51 | return ttl > info->ttl;
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| 52 | }
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| 53 |
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| 54 | return false;
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| 55 | }
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| 56 |
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| 57 | static int hl_mt6_check(const struct xt_mtchk_param *par)
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| 58 | {
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| 59 | const struct ip6t_hl_info *info = par->matchinfo;
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| 60 |
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| 61 | if (info->mode > IP6T_HL_GT) {
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| 62 | pr_info_ratelimited("Unknown Hop Limit match mode: %d\n", info->mode);
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| 63 | return -EINVAL;
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| 64 | }
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| 65 |
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| 66 | return 0;
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| 67 | }
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| 68 |
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| 69 | static bool hl_mt6(const struct sk_buff *skb, struct xt_action_param *par)
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| 70 | {
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| 71 | const struct ip6t_hl_info *info = par->matchinfo;
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| 72 | const struct ipv6hdr *ip6h = ipv6_hdr(skb);
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| 73 |
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| 74 | switch (info->mode) {
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| 75 | case IP6T_HL_EQ:
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| 76 | return ip6h->hop_limit == info->hop_limit;
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| 77 | case IP6T_HL_NE:
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| 78 | return ip6h->hop_limit != info->hop_limit;
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| 79 | case IP6T_HL_LT:
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| 80 | return ip6h->hop_limit < info->hop_limit;
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| 81 | case IP6T_HL_GT:
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| 82 | return ip6h->hop_limit > info->hop_limit;
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| 83 | }
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| 84 |
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| 85 | return false;
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| 86 | }
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| 87 |
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| 88 | static struct xt_match hl_mt_reg[] __read_mostly = {
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| 89 | {
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| 90 | .name = "ttl",
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| 91 | .revision = 0,
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| 92 | .family = NFPROTO_IPV4,
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| 93 | .checkentry = ttl_mt_check,
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| 94 | .match = ttl_mt,
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| 95 | .matchsize = sizeof(struct ipt_ttl_info),
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| 96 | .me = THIS_MODULE,
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| 97 | },
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| 98 | {
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| 99 | .name = "hl",
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| 100 | .revision = 0,
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| 101 | .family = NFPROTO_IPV6,
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| 102 | .checkentry = hl_mt6_check,
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| 103 | .match = hl_mt6,
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| 104 | .matchsize = sizeof(struct ip6t_hl_info),
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| 105 | .me = THIS_MODULE,
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| 106 | },
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| 107 | };
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| 108 |
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| 109 | static int __init hl_mt_init(void)
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| 110 | {
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| 111 | return xt_register_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
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| 112 | }
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| 113 |
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| 114 | static void __exit hl_mt_exit(void)
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| 115 | {
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| 116 | xt_unregister_matches(hl_mt_reg, ARRAY_SIZE(hl_mt_reg));
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| 117 | }
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| 118 |
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| 119 | module_init(hl_mt_init);
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| 120 | module_exit(hl_mt_exit);
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