cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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xt_length.c (1717B)

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