Commit | Line | Data |
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2e4e6a17 HW |
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> | |
37d8dc82 | 11 | #include <linux/ipv6.h> |
2e4e6a17 HW |
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("IP tables packet length matching module"); | |
19 | MODULE_LICENSE("GPL"); | |
20 | MODULE_ALIAS("ipt_length"); | |
21 | MODULE_ALIAS("ip6t_length"); | |
22 | ||
23 | static int | |
24 | match(const struct sk_buff *skb, | |
25 | const struct net_device *in, | |
26 | const struct net_device *out, | |
c4986734 | 27 | const struct xt_match *match, |
2e4e6a17 HW |
28 | const void *matchinfo, |
29 | int offset, | |
30 | unsigned int protoff, | |
31 | int *hotdrop) | |
32 | { | |
33 | const struct xt_length_info *info = matchinfo; | |
34 | u_int16_t pktlen = ntohs(skb->nh.iph->tot_len); | |
35 | ||
36 | return (pktlen >= info->min && pktlen <= info->max) ^ info->invert; | |
37 | } | |
38 | ||
39 | static int | |
40 | match6(const struct sk_buff *skb, | |
41 | const struct net_device *in, | |
42 | const struct net_device *out, | |
c4986734 | 43 | const struct xt_match *match, |
2e4e6a17 HW |
44 | const void *matchinfo, |
45 | int offset, | |
46 | unsigned int protoff, | |
47 | int *hotdrop) | |
48 | { | |
49 | const struct xt_length_info *info = matchinfo; | |
50 | u_int16_t pktlen = ntohs(skb->nh.ipv6h->payload_len) + sizeof(struct ipv6hdr); | |
51 | ||
52 | return (pktlen >= info->min && pktlen <= info->max) ^ info->invert; | |
53 | } | |
54 | ||
4470bbc7 PM |
55 | static struct xt_match xt_length_match[] = { |
56 | { | |
57 | .name = "length", | |
58 | .family = AF_INET, | |
59 | .match = match, | |
60 | .matchsize = sizeof(struct xt_length_info), | |
61 | .me = THIS_MODULE, | |
62 | }, | |
63 | { | |
64 | .name = "length", | |
65 | .family = AF_INET6, | |
66 | .match = match6, | |
67 | .matchsize = sizeof(struct xt_length_info), | |
68 | .me = THIS_MODULE, | |
69 | }, | |
2e4e6a17 HW |
70 | }; |
71 | ||
65b4b4e8 | 72 | static int __init xt_length_init(void) |
2e4e6a17 | 73 | { |
4470bbc7 PM |
74 | return xt_register_matches(xt_length_match, |
75 | ARRAY_SIZE(xt_length_match)); | |
2e4e6a17 HW |
76 | } |
77 | ||
65b4b4e8 | 78 | static void __exit xt_length_fini(void) |
2e4e6a17 | 79 | { |
4470bbc7 | 80 | xt_unregister_matches(xt_length_match, ARRAY_SIZE(xt_length_match)); |
2e4e6a17 HW |
81 | } |
82 | ||
65b4b4e8 AM |
83 | module_init(xt_length_init); |
84 | module_exit(xt_length_fini); |