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| 6 | #include <linux/module.h>
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| 7 | #include <linux/skbuff.h>
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| 8 | #include <linux/ipv6.h>
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| 9 | #include <net/ip.h>
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| 10 |
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| 11 | #include <linux/netfilter/xt_length.h>
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| 12 | #include <linux/netfilter/x_tables.h>
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| 13 |
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| 14 | MODULE_AUTHOR("James Morris <[email protected]>");
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| 15 | MODULE_DESCRIPTION("Xtables: Packet length (Layer3,4,5) match");
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| 16 | MODULE_LICENSE("GPL");
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| 17 | MODULE_ALIAS("ipt_length");
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| 18 | MODULE_ALIAS("ip6t_length");
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| 19 |
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| 20 | static bool
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| 21 | length_mt(const struct sk_buff *skb, struct xt_action_param *par)
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| 22 | {
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| 23 | const struct xt_length_info *info = par->matchinfo;
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| 24 | u32 pktlen = skb_ip_totlen(skb);
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| 25 |
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| 26 | return (pktlen >= info->min && pktlen <= info->max) ^ info->invert;
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| 27 | }
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| 28 |
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| 29 | static bool
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| 30 | length_mt6(const struct sk_buff *skb, struct xt_action_param *par)
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| 31 | {
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| 32 | const struct xt_length_info *info = par->matchinfo;
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| 33 | u32 pktlen = skb->len;
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| 34 |
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| 35 | return (pktlen >= info->min && pktlen <= info->max) ^ info->invert;
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| 36 | }
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| 37 |
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| 38 | static struct xt_match length_mt_reg[] __read_mostly = {
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| 39 | {
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| 40 | .name = "length",
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| 41 | .family = NFPROTO_IPV4,
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| 42 | .match = length_mt,
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| 43 | .matchsize = sizeof(struct xt_length_info),
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| 44 | .me = THIS_MODULE,
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| 45 | },
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| 46 | {
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| 47 | .name = "length",
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| 48 | .family = NFPROTO_IPV6,
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| 49 | .match = length_mt6,
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| 50 | .matchsize = sizeof(struct xt_length_info),
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| 51 | .me = THIS_MODULE,
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| 52 | },
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| 53 | };
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| 54 |
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| 55 | static int __init length_mt_init(void)
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| 56 | {
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| 57 | return xt_register_matches(length_mt_reg, ARRAY_SIZE(length_mt_reg));
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| 58 | }
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| 59 |
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| 60 | static void __exit length_mt_exit(void)
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| 61 | {
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| 62 | xt_unregister_matches(length_mt_reg, ARRAY_SIZE(length_mt_reg));
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| 63 | }
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| 64 |
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| 65 | module_init(length_mt_init);
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| 66 | module_exit(length_mt_exit);
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