// SPDX-License-Identifier: GPL-2.0-or-later/*  Kernel module to match IPComp parameters for IPv4 and IPv6 * *  Copyright (C) 2013 WindRiver * *  Author: *  Fan Du <fan.du@windriver.com> * *  Based on: *  net/netfilter/xt_esp.c */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt#include <linux/in.h>#include <linux/module.h>#include <linux/skbuff.h>#include <linux/ip.h> #include <linux/netfilter/xt_ipcomp.h>#include <linux/netfilter/x_tables.h> MODULE_LICENSE("GPL");MODULE_AUTHOR("Fan Du <fan.du@windriver.com>");MODULE_DESCRIPTION("Xtables: IPv4/6 IPsec-IPComp SPI match");MODULE_ALIAS("ipt_ipcomp");MODULE_ALIAS("ip6t_ipcomp"); /* Returns 1 if the spi is matched by the range, 0 otherwise */static inline boolspi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert){	return (spi >= min && spi <= max) ^ invert;} static bool comp_mt(const struct sk_buff *skb, struct xt_action_param *par){	struct ip_comp_hdr _comphdr;	const struct ip_comp_hdr *chdr;	const struct xt_ipcomp *compinfo = par->matchinfo; 	/* Must not be a fragment. */	if (par->fragoff != 0)		return false; 	chdr = skb_header_pointer(skb, par->thoff, sizeof(_comphdr), &_comphdr);	if (chdr == NULL) {		/* We've been asked to examine this packet, and we		 * can't.  Hence, no choice but to drop.		 */		par->hotdrop = true;		return false;	} 	return spi_match(compinfo->spis[0], compinfo->spis[1],			 ntohs(chdr->cpi),			 !!(compinfo->invflags & XT_IPCOMP_INV_SPI));} static int comp_mt_check(const struct xt_mtchk_param *par){	const struct xt_ipcomp *compinfo = par->matchinfo; 	/* Must specify no unknown invflags */	if (compinfo->invflags & ~XT_IPCOMP_INV_MASK) {		pr_info_ratelimited("unknown flags %X\n", compinfo->invflags);		return -EINVAL;	}	return 0;} static struct xt_match comp_mt_reg[] __read_mostly = {	{		.name		= "ipcomp",		.family		= NFPROTO_IPV4,		.match		= comp_mt,		.matchsize	= sizeof(struct xt_ipcomp),		.proto		= IPPROTO_COMP,		.checkentry	= comp_mt_check,		.me		= THIS_MODULE,	},	{		.name		= "ipcomp",		.family		= NFPROTO_IPV6,		.match		= comp_mt,		.matchsize	= sizeof(struct xt_ipcomp),		.proto		= IPPROTO_COMP,		.checkentry	= comp_mt_check,		.me		= THIS_MODULE,	},}; static int __init comp_mt_init(void){	return xt_register_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));} static void __exit comp_mt_exit(void){	xt_unregister_matches(comp_mt_reg, ARRAY_SIZE(comp_mt_reg));} module_init(comp_mt_init);module_exit(comp_mt_exit);