x25: use limited socket backlog
[linux-2.6.git] / net / netfilter / xt_length.c
1 /* Kernel module to match packet length. */
2 /* (C) 1999-2001 James Morris <jmorros@intercode.com.au>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  */
8
9 #include <linux/module.h>
10 #include <linux/skbuff.h>
11 #include <linux/ipv6.h>
12 #include <net/ip.h>
13
14 #include <linux/netfilter/xt_length.h>
15 #include <linux/netfilter/x_tables.h>
16
17 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
18 MODULE_DESCRIPTION("Xtables: Packet length (Layer3,4,5) match");
19 MODULE_LICENSE("GPL");
20 MODULE_ALIAS("ipt_length");
21 MODULE_ALIAS("ip6t_length");
22
23 static bool
24 length_mt(const struct sk_buff *skb, const struct xt_match_param *par)
25 {
26         const struct xt_length_info *info = par->matchinfo;
27         u_int16_t pktlen = ntohs(ip_hdr(skb)->tot_len);
28
29         return (pktlen >= info->min && pktlen <= info->max) ^ info->invert;
30 }
31
32 static bool
33 length_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
34 {
35         const struct xt_length_info *info = par->matchinfo;
36         const u_int16_t pktlen = ntohs(ipv6_hdr(skb)->payload_len) +
37                                  sizeof(struct ipv6hdr);
38
39         return (pktlen >= info->min && pktlen <= info->max) ^ info->invert;
40 }
41
42 static struct xt_match length_mt_reg[] __read_mostly = {
43         {
44                 .name           = "length",
45                 .family         = NFPROTO_IPV4,
46                 .match          = length_mt,
47                 .matchsize      = sizeof(struct xt_length_info),
48                 .me             = THIS_MODULE,
49         },
50         {
51                 .name           = "length",
52                 .family         = NFPROTO_IPV6,
53                 .match          = length_mt6,
54                 .matchsize      = sizeof(struct xt_length_info),
55                 .me             = THIS_MODULE,
56         },
57 };
58
59 static int __init length_mt_init(void)
60 {
61         return xt_register_matches(length_mt_reg, ARRAY_SIZE(length_mt_reg));
62 }
63
64 static void __exit length_mt_exit(void)
65 {
66         xt_unregister_matches(length_mt_reg, ARRAY_SIZE(length_mt_reg));
67 }
68
69 module_init(length_mt_init);
70 module_exit(length_mt_exit);