/* Kernel module to match ESP parameters. */ /* (C) 1999-2000 Yon Uriarte <yon@astaro.de> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #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("x_tables ESP SPI match module");MODULE_ALIAS("ipt_esp");MODULE_ALIAS("ip6t_esp"); #if 0#define duprintf(format, args...) printk(format , ## args)#else#define duprintf(format, args...)#endif /* Returns 1 if the spi is matched by the range, 0 otherwise */static inline intspi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert){	int r = 0;	duprintf("esp spi_match:%c 0x%x <= 0x%x <= 0x%x", invert ? '!' : ' ',		 min, spi, max);	r = (spi >= min && spi <= max) ^ invert;	duprintf(" result %s\n", r ? "PASS" : "FAILED");	return r;} static intmatch(const struct sk_buff *skb,      const struct net_device *in,      const struct net_device *out,      const struct xt_match *match,      const void *matchinfo,      int offset,      unsigned int protoff,      int *hotdrop){	struct ip_esp_hdr _esp, *eh;	const struct xt_esp *espinfo = matchinfo; 	/* Must not be a fragment. */	if (offset)		return 0; 	eh = skb_header_pointer(skb, protoff, sizeof(_esp), &_esp);	if (eh == NULL) {		/* We've been asked to examine this packet, and we		 * can't.  Hence, no choice but to drop.		 */		duprintf("Dropping evil ESP tinygram.\n");		*hotdrop = 1;		return 0;	} 	return spi_match(espinfo->spis[0], espinfo->spis[1], ntohl(eh->spi),			 !!(espinfo->invflags & XT_ESP_INV_SPI));} /* Called when user tries to insert an entry of this type. */static intcheckentry(const char *tablename,	   const void *ip_void,	   const struct xt_match *match,	   void *matchinfo,	   unsigned int matchinfosize,	   unsigned int hook_mask){	const struct xt_esp *espinfo = matchinfo; 	if (espinfo->invflags & ~XT_ESP_INV_MASK) {		duprintf("xt_esp: unknown flags %X\n", espinfo->invflags);		return 0;	} 	return 1;} static struct xt_match esp_match = {	.name		= "esp",	.family		= AF_INET,	.proto		= IPPROTO_ESP,	.match		= &match,	.matchsize	= sizeof(struct xt_esp),	.checkentry	= &checkentry,	.me		= THIS_MODULE,}; static struct xt_match esp6_match = {	.name		= "esp",	.family		= AF_INET6,	.proto		= IPPROTO_ESP,	.match		= &match,	.matchsize	= sizeof(struct xt_esp),	.checkentry	= &checkentry,	.me		= THIS_MODULE,}; static int __init xt_esp_init(void){	int ret;	ret = xt_register_match(&esp_match);	if (ret)		return ret; 	ret = xt_register_match(&esp6_match);	if (ret)		xt_unregister_match(&esp_match); 	return ret;} static void __exit xt_esp_cleanup(void){	xt_unregister_match(&esp_match);	xt_unregister_match(&esp6_match);} module_init(xt_esp_init);module_exit(xt_esp_cleanup);