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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
2e4e6a17 HW |
2 | /* Kernel module to match packet length. */ |
3 | /* (C) 1999-2001 James Morris <jmorros@intercode.com.au> | |
2e4e6a17 HW |
4 | */ |
5 | ||
6 | #include <linux/module.h> | |
7 | #include <linux/skbuff.h> | |
37d8dc82 | 8 | #include <linux/ipv6.h> |
2e4e6a17 HW |
9 | #include <net/ip.h> |
10 | ||
11 | #include <linux/netfilter/xt_length.h> | |
12 | #include <linux/netfilter/x_tables.h> | |
13 | ||
14 | MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); | |
2ae15b64 | 15 | MODULE_DESCRIPTION("Xtables: Packet length (Layer3,4,5) match"); |
2e4e6a17 HW |
16 | MODULE_LICENSE("GPL"); |
17 | MODULE_ALIAS("ipt_length"); | |
18 | MODULE_ALIAS("ip6t_length"); | |
19 | ||
1d93a9cb | 20 | static bool |
62fc8051 | 21 | length_mt(const struct sk_buff *skb, struct xt_action_param *par) |
2e4e6a17 | 22 | { |
f7108a20 | 23 | const struct xt_length_info *info = par->matchinfo; |
eddc9ec5 | 24 | u_int16_t pktlen = ntohs(ip_hdr(skb)->tot_len); |
601e68e1 | 25 | |
2e4e6a17 HW |
26 | return (pktlen >= info->min && pktlen <= info->max) ^ info->invert; |
27 | } | |
28 | ||
1d93a9cb | 29 | static bool |
62fc8051 | 30 | length_mt6(const struct sk_buff *skb, struct xt_action_param *par) |
2e4e6a17 | 31 | { |
f7108a20 | 32 | const struct xt_length_info *info = par->matchinfo; |
7c4e36bc JE |
33 | const u_int16_t pktlen = ntohs(ipv6_hdr(skb)->payload_len) + |
34 | sizeof(struct ipv6hdr); | |
601e68e1 | 35 | |
2e4e6a17 HW |
36 | return (pktlen >= info->min && pktlen <= info->max) ^ info->invert; |
37 | } | |
38 | ||
d3c5ee6d | 39 | static struct xt_match length_mt_reg[] __read_mostly = { |
4470bbc7 PM |
40 | { |
41 | .name = "length", | |
ee999d8b | 42 | .family = NFPROTO_IPV4, |
d3c5ee6d | 43 | .match = length_mt, |
4470bbc7 PM |
44 | .matchsize = sizeof(struct xt_length_info), |
45 | .me = THIS_MODULE, | |
46 | }, | |
47 | { | |
48 | .name = "length", | |
ee999d8b | 49 | .family = NFPROTO_IPV6, |
d3c5ee6d | 50 | .match = length_mt6, |
4470bbc7 PM |
51 | .matchsize = sizeof(struct xt_length_info), |
52 | .me = THIS_MODULE, | |
53 | }, | |
2e4e6a17 HW |
54 | }; |
55 | ||
d3c5ee6d | 56 | static int __init length_mt_init(void) |
2e4e6a17 | 57 | { |
d3c5ee6d | 58 | return xt_register_matches(length_mt_reg, ARRAY_SIZE(length_mt_reg)); |
2e4e6a17 HW |
59 | } |
60 | ||
d3c5ee6d | 61 | static void __exit length_mt_exit(void) |
2e4e6a17 | 62 | { |
d3c5ee6d | 63 | xt_unregister_matches(length_mt_reg, ARRAY_SIZE(length_mt_reg)); |
2e4e6a17 HW |
64 | } |
65 | ||
d3c5ee6d JE |
66 | module_init(length_mt_init); |
67 | module_exit(length_mt_exit); |