// SPDX-License-Identifier: GPL-2.0-only/* Kernel module to match ESP parameters. */ /* (C) 1999-2000 Yon Uriarte <yon@astaro.de> */#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt#include <linux/module.h>#include <linux/skbuff.h>#include <linux/in.h>#include <linux/ip.h> #include <linux/netfilter/xt_esp.h>#include <linux/netfilter/x_tables.h> #include <linux/netfilter_ipv4/ip_tables.h>#include <linux/netfilter_ipv6/ip6_tables.h> MODULE_LICENSE("GPL");MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>");MODULE_DESCRIPTION("Xtables: IPsec-ESP packet match");MODULE_ALIAS("ipt_esp");MODULE_ALIAS("ip6t_esp"); /* 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 esp_mt(const struct sk_buff *skb, struct xt_action_param *par){	const struct ip_esp_hdr *eh;	struct ip_esp_hdr _esp;	const struct xt_esp *espinfo = par->matchinfo; 	/* Must not be a fragment. */	if (par->fragoff != 0)		return false; 	eh = skb_header_pointer(skb, par->thoff, sizeof(_esp), &_esp);	if (eh == 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(espinfo->spis[0], espinfo->spis[1], ntohl(eh->spi),			 !!(espinfo->invflags & XT_ESP_INV_SPI));} static int esp_mt_check(const struct xt_mtchk_param *par){	const struct xt_esp *espinfo = par->matchinfo; 	if (espinfo->invflags & ~XT_ESP_INV_MASK) {		pr_info_ratelimited("unknown flags %X\n", espinfo->invflags);		return -EINVAL;	} 	return 0;} static struct xt_match esp_mt_reg[] __read_mostly = {	{		.name		= "esp",		.family		= NFPROTO_IPV4,		.checkentry	= esp_mt_check,		.match		= esp_mt,		.matchsize	= sizeof(struct xt_esp),		.proto		= IPPROTO_ESP,		.me		= THIS_MODULE,	},	{		.name		= "esp",		.family		= NFPROTO_IPV6,		.checkentry	= esp_mt_check,		.match		= esp_mt,		.matchsize	= sizeof(struct xt_esp),		.proto		= IPPROTO_ESP,		.me		= THIS_MODULE,	},}; static int __init esp_mt_init(void){	return xt_register_matches(esp_mt_reg, ARRAY_SIZE(esp_mt_reg));} static void __exit esp_mt_exit(void){	xt_unregister_matches(esp_mt_reg, ARRAY_SIZE(esp_mt_reg));} module_init(esp_mt_init);module_exit(esp_mt_exit);