net/ipv6/mip6.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Copyright (C)2003-2006 Helsinki University of Technology
  * Copyright (C)2003-2006 USAGI/WIDE Project
  */
 /*
  * Authors:
  *	Noriaki TAKAMIYA @USAGI
  *	Masahide NAKAMURA @USAGI
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/module.h>
 #include <linux/skbuff.h>
 #include <linux/time.h>
 #include <linux/ipv6.h>
 #include <linux/icmpv6.h>
 #include <net/sock.h>
 #include <net/ipv6.h>
 #include <net/ip6_checksum.h>
 #include <net/rawv6.h>
 #include <net/xfrm.h>
 #include <net/mip6.h>

 static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
 {
 	return (n - len + 16) & 0x7;
 }

 static inline void *mip6_padn(__u8 *data, __u8 padlen)
 {
 	if (!data)
 		return NULL;
 	if (padlen == 1) {
 		data[0] = IPV6_TLV_PAD1;
 	} else if (padlen > 1) {
 		data[0] = IPV6_TLV_PADN;
 		data[1] = padlen - 2;
 		if (padlen > 2)
 			memset(data+2, 0, data[1]);
 	}
 	return data + padlen;
 }

 static inline void mip6_param_prob(struct sk_buff *skb, u8 code, int pos)
 {
 	icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos);
 }

 static int mip6_mh_len(int type)
 {
 	int len = 0;

 	switch (type) {
 	case IP6_MH_TYPE_BRR:
 		len = 0;
 		break;
 	case IP6_MH_TYPE_HOTI:
 	case IP6_MH_TYPE_COTI:
 	case IP6_MH_TYPE_BU:
 	case IP6_MH_TYPE_BACK:
 		len = 1;
 		break;
 	case IP6_MH_TYPE_HOT:
 	case IP6_MH_TYPE_COT:
 	case IP6_MH_TYPE_BERROR:
 		len = 2;
 		break;
 	}
 	return len;
 }

 static int mip6_mh_filter(struct sock *sk, struct sk_buff *skb)
 {
 	struct ip6_mh _hdr;
 	const struct ip6_mh *mh;

 	mh = skb_header_pointer(skb, skb_transport_offset(skb),
 				sizeof(_hdr), &_hdr);
 	if (!mh)
 		return -1;

 	if (((mh->ip6mh_hdrlen + 1) << 3) > skb->len)
 		return -1;

 	if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
 		net_dbg_ratelimited("mip6: MH message too short: %d vs >=%d\n",
 				    mh->ip6mh_hdrlen,
 				    mip6_mh_len(mh->ip6mh_type));
 		mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_hdrlen) +
 				skb_network_header_len(skb));
 		return -1;
 	}

 	if (mh->ip6mh_proto != IPPROTO_NONE) {
 		net_dbg_ratelimited("mip6: MH invalid payload proto = %d\n",
 				    mh->ip6mh_proto);
 		mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_proto) +
 				skb_network_header_len(skb));
 		return -1;
 	}

 	return 0;
 }

 struct mip6_report_rate_limiter {
 	spinlock_t lock;
 	ktime_t stamp;
 	int iif;
 	struct in6_addr src;
 	struct in6_addr dst;
 };

 static struct mip6_report_rate_limiter mip6_report_rl = {
 	.lock = __SPIN_LOCK_UNLOCKED(mip6_report_rl.lock)
 };

 static int mip6_destopt_input(struct xfrm_state *x, struct sk_buff *skb)
 {
 	const struct ipv6hdr *iph = ipv6_hdr(skb);
 	struct ipv6_destopt_hdr *destopt = (struct ipv6_destopt_hdr *)skb->data;
 	int err = destopt->nexthdr;

 	spin_lock(&x->lock);
 	if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
 	    !ipv6_addr_any((struct in6_addr *)x->coaddr))
 		err = -ENOENT;
 	spin_unlock(&x->lock);

 	return err;
 }

 /* Destination Option Header is inserted.
  * IP Header's src address is replaced with Home Address Option in
  * Destination Option Header.
  */
 static int mip6_destopt_output(struct xfrm_state *x, struct sk_buff *skb)
 {
 	struct ipv6hdr *iph;
 	struct ipv6_destopt_hdr *dstopt;
 	struct ipv6_destopt_hao *hao;
 	u8 nexthdr;
 	int len;

 	skb_push(skb, -skb_network_offset(skb));
 	iph = ipv6_hdr(skb);

 	nexthdr = *skb_mac_header(skb);
 	*skb_mac_header(skb) = IPPROTO_DSTOPTS;

 	dstopt = (struct ipv6_destopt_hdr *)skb_transport_header(skb);
 	dstopt->nexthdr = nexthdr;

 	hao = mip6_padn((char *)(dstopt + 1),
 			calc_padlen(sizeof(*dstopt), 6));

 	hao->type = IPV6_TLV_HAO;
 	BUILD_BUG_ON(sizeof(*hao) != 18);
 	hao->length = sizeof(*hao) - 2;

 	len = ((char *)hao - (char *)dstopt) + sizeof(*hao);

 	memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
 	spin_lock_bh(&x->lock);
 	memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
 	spin_unlock_bh(&x->lock);

 	WARN_ON(len != x->props.header_len);
 	dstopt->hdrlen = (x->props.header_len >> 3) - 1;

 	return 0;
 }

 static inline int mip6_report_rl_allow(ktime_t stamp,
 				       const struct in6_addr *dst,
 				       const struct in6_addr *src, int iif)
 {
 	int allow = 0;

 	spin_lock_bh(&mip6_report_rl.lock);
 	if (mip6_report_rl.stamp != stamp ||
 	    mip6_report_rl.iif != iif ||
 	    !ipv6_addr_equal(&mip6_report_rl.src, src) ||
 	    !ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
 		mip6_report_rl.stamp = stamp;
 		mip6_report_rl.iif = iif;
 		mip6_report_rl.src = *src;
 		mip6_report_rl.dst = *dst;
 		allow = 1;
 	}
 	spin_unlock_bh(&mip6_report_rl.lock);
 	return allow;
 }

 static int mip6_destopt_reject(struct xfrm_state *x, struct sk_buff *skb,
 			       const struct flowi *fl)
 {
 	struct net *net = xs_net(x);
 	struct inet6_skb_parm *opt = (struct inet6_skb_parm *)skb->cb;
 	const struct flowi6 *fl6 = &fl->u.ip6;
 	struct ipv6_destopt_hao *hao = NULL;
 	struct xfrm_selector sel;
 	int offset;
 	ktime_t stamp;
 	int err = 0;

 	if (unlikely(fl6->flowi6_proto == IPPROTO_MH &&
 		     fl6->fl6_mh_type <= IP6_MH_TYPE_MAX))
 		goto out;

 	if (likely(opt->dsthao)) {
 		offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
 		if (likely(offset >= 0))
 			hao = (struct ipv6_destopt_hao *)
 					(skb_network_header(skb) + offset);
 	}

 	stamp = skb_get_ktime(skb);

 	if (!mip6_report_rl_allow(stamp, &ipv6_hdr(skb)->daddr,
 				  hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
 				  opt->iif))
 		goto out;

 	memset(&sel, 0, sizeof(sel));
 	memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
 	       sizeof(sel.daddr));
 	sel.prefixlen_d = 128;
 	memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
 	       sizeof(sel.saddr));
 	sel.prefixlen_s = 128;
 	sel.family = AF_INET6;
 	sel.proto = fl6->flowi6_proto;
 	sel.dport = xfrm_flowi_dport(fl, &fl6->uli);
 	if (sel.dport)
 		sel.dport_mask = htons(~0);
 	sel.sport = xfrm_flowi_sport(fl, &fl6->uli);
 	if (sel.sport)
 		sel.sport_mask = htons(~0);
 	sel.ifindex = fl6->flowi6_oif;

 	err = km_report(net, IPPROTO_DSTOPTS, &sel,
 			(hao ? (xfrm_address_t *)&hao->addr : NULL));

  out:
 	return err;
 }

 static int mip6_destopt_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
 {
 	if (x->id.spi) {
 		NL_SET_ERR_MSG(extack, "SPI must be 0");
 		return -EINVAL;
 	}
 	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 		NL_SET_ERR_MSG(extack, "XFRM mode must be XFRM_MODE_ROUTEOPTIMIZATION");
 		return -EINVAL;
 	}

 	x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
 		calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
 		sizeof(struct ipv6_destopt_hao);
 	WARN_ON(x->props.header_len != 24);

 	return 0;
 }

 /*
  * Do nothing about destroying since it has no specific operation for
  * destination options header unlike IPsec protocols.
  */
 static void mip6_destopt_destroy(struct xfrm_state *x)
 {
 }

 static const struct xfrm_type mip6_destopt_type = {
 	.owner		= THIS_MODULE,
 	.proto		= IPPROTO_DSTOPTS,
 	.flags		= XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_LOCAL_COADDR,
 	.init_state	= mip6_destopt_init_state,
 	.destructor	= mip6_destopt_destroy,
 	.input		= mip6_destopt_input,
 	.output		= mip6_destopt_output,
 	.reject		= mip6_destopt_reject,
 };

 static int mip6_rthdr_input(struct xfrm_state *x, struct sk_buff *skb)
 {
 	const struct ipv6hdr *iph = ipv6_hdr(skb);
 	struct rt2_hdr *rt2 = (struct rt2_hdr *)skb->data;
 	int err = rt2->rt_hdr.nexthdr;

 	spin_lock(&x->lock);
 	if (!ipv6_addr_equal(&iph->daddr, (struct in6_addr *)x->coaddr) &&
 	    !ipv6_addr_any((struct in6_addr *)x->coaddr))
 		err = -ENOENT;
 	spin_unlock(&x->lock);

 	return err;
 }

 /* Routing Header type 2 is inserted.
  * IP Header's dst address is replaced with Routing Header's Home Address.
  */
 static int mip6_rthdr_output(struct xfrm_state *x, struct sk_buff *skb)
 {
 	struct ipv6hdr *iph;
 	struct rt2_hdr *rt2;
 	u8 nexthdr;

 	skb_push(skb, -skb_network_offset(skb));
 	iph = ipv6_hdr(skb);

 	nexthdr = *skb_mac_header(skb);
 	*skb_mac_header(skb) = IPPROTO_ROUTING;

 	rt2 = (struct rt2_hdr *)skb_transport_header(skb);
 	rt2->rt_hdr.nexthdr = nexthdr;
 	rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
 	rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
 	rt2->rt_hdr.segments_left = 1;
 	memset(&rt2->reserved, 0, sizeof(rt2->reserved));

 	WARN_ON(rt2->rt_hdr.hdrlen != 2);

 	memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
 	spin_lock_bh(&x->lock);
 	memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
 	spin_unlock_bh(&x->lock);

 	return 0;
 }

 static int mip6_rthdr_init_state(struct xfrm_state *x, struct netlink_ext_ack *extack)
 {
 	if (x->id.spi) {
 		NL_SET_ERR_MSG(extack, "SPI must be 0");
 		return -EINVAL;
 	}
 	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
 		NL_SET_ERR_MSG(extack, "XFRM mode must be XFRM_MODE_ROUTEOPTIMIZATION");
 		return -EINVAL;
 	}

 	x->props.header_len = sizeof(struct rt2_hdr);

 	return 0;
 }

 /*
  * Do nothing about destroying since it has no specific operation for routing
  * header type 2 unlike IPsec protocols.
  */
 static void mip6_rthdr_destroy(struct xfrm_state *x)
 {
 }

 static const struct xfrm_type mip6_rthdr_type = {
 	.owner		= THIS_MODULE,
 	.proto		= IPPROTO_ROUTING,
 	.flags		= XFRM_TYPE_NON_FRAGMENT | XFRM_TYPE_REMOTE_COADDR,
 	.init_state	= mip6_rthdr_init_state,
 	.destructor	= mip6_rthdr_destroy,
 	.input		= mip6_rthdr_input,
 	.output		= mip6_rthdr_output,
 };

 static int __init mip6_init(void)
 {
 	pr_info("Mobile IPv6\n");

 	if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
 		pr_info("%s: can't add xfrm type(destopt)\n", __func__);
 		goto mip6_destopt_xfrm_fail;
 	}
 	if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
 		pr_info("%s: can't add xfrm type(rthdr)\n", __func__);
 		goto mip6_rthdr_xfrm_fail;
 	}
 	if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
 		pr_info("%s: can't add rawv6 mh filter\n", __func__);
 		goto mip6_rawv6_mh_fail;
 	}


 	return 0;

  mip6_rawv6_mh_fail:
 	xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
  mip6_rthdr_xfrm_fail:
 	xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
  mip6_destopt_xfrm_fail:
 	return -EAGAIN;
 }

 static void __exit mip6_fini(void)
 {
 	if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
 		pr_info("%s: can't remove rawv6 mh filter\n", __func__);
 	xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
 	xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
 }

 module_init(mip6_init);
 module_exit(mip6_fini);

 MODULE_LICENSE("GPL");
 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Copyright (C)2003-2006 Helsinki University of Technology
	* Copyright (C)2003-2006 USAGI/WIDE Project
	*/
	/*
	* Authors:
	* Noriaki TAKAMIYA @USAGI
	* Masahide NAKAMURA @USAGI
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/module.h>
	#include <linux/skbuff.h>
	#include <linux/time.h>
	#include <linux/ipv6.h>
	#include <linux/icmpv6.h>
	#include <net/sock.h>
	#include <net/ipv6.h>
	#include <net/ip6_checksum.h>
	#include <net/rawv6.h>
	#include <net/xfrm.h>
	#include <net/mip6.h>

	static inline unsigned int calc_padlen(unsigned int len, unsigned int n)
	{
	return (n - len + 16) & 0x7;
	}

	static inline void mip6_padn(__u8 data, __u8 padlen)
	{
	if (!data)
	return NULL;
	if (padlen == 1) {
	data[0] = IPV6_TLV_PAD1;
	} else if (padlen > 1) {
	data[0] = IPV6_TLV_PADN;
	data[1] = padlen - 2;
	if (padlen > 2)
	memset(data+2, 0, data[1]);
	}
	return data + padlen;
	}

	static inline void mip6_param_prob(struct sk_buff *skb, u8 code, int pos)
	{
	icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos);
	}

	static int mip6_mh_len(int type)
	{
	int len = 0;

	switch (type) {
	case IP6_MH_TYPE_BRR:
	len = 0;
	break;
	case IP6_MH_TYPE_HOTI:
	case IP6_MH_TYPE_COTI:
	case IP6_MH_TYPE_BU:
	case IP6_MH_TYPE_BACK:
	len = 1;
	break;
	case IP6_MH_TYPE_HOT:
	case IP6_MH_TYPE_COT:
	case IP6_MH_TYPE_BERROR:
	len = 2;
	break;
	}
	return len;
	}

	static int mip6_mh_filter(struct sock sk, struct sk_buff skb)
	{
	struct ip6_mh _hdr;
	const struct ip6_mh *mh;

	mh = skb_header_pointer(skb, skb_transport_offset(skb),
	sizeof(_hdr), &_hdr);
	if (!mh)
	return -1;

	if (((mh->ip6mh_hdrlen + 1) << 3) > skb->len)
	return -1;

	if (mh->ip6mh_hdrlen < mip6_mh_len(mh->ip6mh_type)) {
	net_dbg_ratelimited("mip6: MH message too short: %d vs >=%d\n",
	mh->ip6mh_hdrlen,
	mip6_mh_len(mh->ip6mh_type));
	mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_hdrlen) +
	skb_network_header_len(skb));
	return -1;
	}

	if (mh->ip6mh_proto != IPPROTO_NONE) {
	net_dbg_ratelimited("mip6: MH invalid payload proto = %d\n",
	mh->ip6mh_proto);
	mip6_param_prob(skb, 0, offsetof(struct ip6_mh, ip6mh_proto) +
	skb_network_header_len(skb));
	return -1;
	}

	return 0;
	}

	struct mip6_report_rate_limiter {
	spinlock_t lock;
	ktime_t stamp;
	int iif;
	struct in6_addr src;
	struct in6_addr dst;
	};

	static struct mip6_report_rate_limiter mip6_report_rl = {
	.lock = __SPIN_LOCK_UNLOCKED(mip6_report_rl.lock)
	};

	static int mip6_destopt_input(struct xfrm_state x, struct sk_buff skb)
	{
	const struct ipv6hdr *iph = ipv6_hdr(skb);
	struct ipv6_destopt_hdr destopt = (struct ipv6_destopt_hdr )skb->data;
	int err = destopt->nexthdr;

	spin_lock(&x->lock);
	if (!ipv6_addr_equal(&iph->saddr, (struct in6_addr *)x->coaddr) &&
	!ipv6_addr_any((struct in6_addr *)x->coaddr))
	err = -ENOENT;
	spin_unlock(&x->lock);

	return err;
	}

	/* Destination Option Header is inserted.
	* IP Header's src address is replaced with Home Address Option in
	* Destination Option Header.
	*/
	static int mip6_destopt_output(struct xfrm_state x, struct sk_buff skb)
	{
	struct ipv6hdr *iph;
	struct ipv6_destopt_hdr *dstopt;
	struct ipv6_destopt_hao *hao;
	u8 nexthdr;
	int len;

	skb_push(skb, -skb_network_offset(skb));
	iph = ipv6_hdr(skb);

	nexthdr = *skb_mac_header(skb);
	*skb_mac_header(skb) = IPPROTO_DSTOPTS;

	dstopt = (struct ipv6_destopt_hdr *)skb_transport_header(skb);
	dstopt->nexthdr = nexthdr;

	hao = mip6_padn((char *)(dstopt + 1),
	calc_padlen(sizeof(*dstopt), 6));

	hao->type = IPV6_TLV_HAO;
	BUILD_BUG_ON(sizeof(*hao) != 18);
	hao->length = sizeof(*hao) - 2;

	len = ((char )hao - (char )dstopt) + sizeof(*hao);

	memcpy(&hao->addr, &iph->saddr, sizeof(hao->addr));
	spin_lock_bh(&x->lock);
	memcpy(&iph->saddr, x->coaddr, sizeof(iph->saddr));
	spin_unlock_bh(&x->lock);

	WARN_ON(len != x->props.header_len);
	dstopt->hdrlen = (x->props.header_len >> 3) - 1;

	return 0;
	}

	static inline int mip6_report_rl_allow(ktime_t stamp,
	const struct in6_addr *dst,
	const struct in6_addr *src, int iif)
	{
	int allow = 0;

	spin_lock_bh(&mip6_report_rl.lock);
	if (mip6_report_rl.stamp != stamp \|\|
	mip6_report_rl.iif != iif \|\|
	!ipv6_addr_equal(&mip6_report_rl.src, src) \|\|
	!ipv6_addr_equal(&mip6_report_rl.dst, dst)) {
	mip6_report_rl.stamp = stamp;
	mip6_report_rl.iif = iif;
	mip6_report_rl.src = *src;
	mip6_report_rl.dst = *dst;
	allow = 1;
	}
	spin_unlock_bh(&mip6_report_rl.lock);
	return allow;
	}

	static int mip6_destopt_reject(struct xfrm_state x, struct sk_buff skb,
	const struct flowi *fl)
	{
	struct net *net = xs_net(x);
	struct inet6_skb_parm opt = (struct inet6_skb_parm )skb->cb;
	const struct flowi6 *fl6 = &fl->u.ip6;
	struct ipv6_destopt_hao *hao = NULL;
	struct xfrm_selector sel;
	int offset;
	ktime_t stamp;
	int err = 0;

	if (unlikely(fl6->flowi6_proto == IPPROTO_MH &&
	fl6->fl6_mh_type <= IP6_MH_TYPE_MAX))
	goto out;

	if (likely(opt->dsthao)) {
	offset = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
	if (likely(offset >= 0))
	hao = (struct ipv6_destopt_hao *)
	(skb_network_header(skb) + offset);
	}

	stamp = skb_get_ktime(skb);

	if (!mip6_report_rl_allow(stamp, &ipv6_hdr(skb)->daddr,
	hao ? &hao->addr : &ipv6_hdr(skb)->saddr,
	opt->iif))
	goto out;

	memset(&sel, 0, sizeof(sel));
	memcpy(&sel.daddr, (xfrm_address_t *)&ipv6_hdr(skb)->daddr,
	sizeof(sel.daddr));
	sel.prefixlen_d = 128;
	memcpy(&sel.saddr, (xfrm_address_t *)&ipv6_hdr(skb)->saddr,
	sizeof(sel.saddr));
	sel.prefixlen_s = 128;
	sel.family = AF_INET6;
	sel.proto = fl6->flowi6_proto;
	sel.dport = xfrm_flowi_dport(fl, &fl6->uli);
	if (sel.dport)
	sel.dport_mask = htons(~0);
	sel.sport = xfrm_flowi_sport(fl, &fl6->uli);
	if (sel.sport)
	sel.sport_mask = htons(~0);
	sel.ifindex = fl6->flowi6_oif;

	err = km_report(net, IPPROTO_DSTOPTS, &sel,
	(hao ? (xfrm_address_t *)&hao->addr : NULL));

	out:
	return err;
	}

	static int mip6_destopt_init_state(struct xfrm_state x, struct netlink_ext_ack extack)
	{
	if (x->id.spi) {
	NL_SET_ERR_MSG(extack, "SPI must be 0");
	return -EINVAL;
	}
	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
	NL_SET_ERR_MSG(extack, "XFRM mode must be XFRM_MODE_ROUTEOPTIMIZATION");
	return -EINVAL;
	}

	x->props.header_len = sizeof(struct ipv6_destopt_hdr) +
	calc_padlen(sizeof(struct ipv6_destopt_hdr), 6) +
	sizeof(struct ipv6_destopt_hao);
	WARN_ON(x->props.header_len != 24);

	return 0;
	}

	/*
	* Do nothing about destroying since it has no specific operation for
	* destination options header unlike IPsec protocols.
	*/
	static void mip6_destopt_destroy(struct xfrm_state *x)
	{
	}

	static const struct xfrm_type mip6_destopt_type = {
	.owner = THIS_MODULE,
	.proto = IPPROTO_DSTOPTS,
	.flags = XFRM_TYPE_NON_FRAGMENT \| XFRM_TYPE_LOCAL_COADDR,
	.init_state = mip6_destopt_init_state,
	.destructor = mip6_destopt_destroy,
	.input = mip6_destopt_input,
	.output = mip6_destopt_output,
	.reject = mip6_destopt_reject,
	};

	static int mip6_rthdr_input(struct xfrm_state x, struct sk_buff skb)
	{
	const struct ipv6hdr *iph = ipv6_hdr(skb);
	struct rt2_hdr rt2 = (struct rt2_hdr )skb->data;
	int err = rt2->rt_hdr.nexthdr;

	spin_lock(&x->lock);
	if (!ipv6_addr_equal(&iph->daddr, (struct in6_addr *)x->coaddr) &&
	!ipv6_addr_any((struct in6_addr *)x->coaddr))
	err = -ENOENT;
	spin_unlock(&x->lock);

	return err;
	}

	/* Routing Header type 2 is inserted.
	* IP Header's dst address is replaced with Routing Header's Home Address.
	*/
	static int mip6_rthdr_output(struct xfrm_state x, struct sk_buff skb)
	{
	struct ipv6hdr *iph;
	struct rt2_hdr *rt2;
	u8 nexthdr;

	skb_push(skb, -skb_network_offset(skb));
	iph = ipv6_hdr(skb);

	nexthdr = *skb_mac_header(skb);
	*skb_mac_header(skb) = IPPROTO_ROUTING;

	rt2 = (struct rt2_hdr *)skb_transport_header(skb);
	rt2->rt_hdr.nexthdr = nexthdr;
	rt2->rt_hdr.hdrlen = (x->props.header_len >> 3) - 1;
	rt2->rt_hdr.type = IPV6_SRCRT_TYPE_2;
	rt2->rt_hdr.segments_left = 1;
	memset(&rt2->reserved, 0, sizeof(rt2->reserved));

	WARN_ON(rt2->rt_hdr.hdrlen != 2);

	memcpy(&rt2->addr, &iph->daddr, sizeof(rt2->addr));
	spin_lock_bh(&x->lock);
	memcpy(&iph->daddr, x->coaddr, sizeof(iph->daddr));
	spin_unlock_bh(&x->lock);

	return 0;
	}

	static int mip6_rthdr_init_state(struct xfrm_state x, struct netlink_ext_ack extack)
	{
	if (x->id.spi) {
	NL_SET_ERR_MSG(extack, "SPI must be 0");
	return -EINVAL;
	}
	if (x->props.mode != XFRM_MODE_ROUTEOPTIMIZATION) {
	NL_SET_ERR_MSG(extack, "XFRM mode must be XFRM_MODE_ROUTEOPTIMIZATION");
	return -EINVAL;
	}

	x->props.header_len = sizeof(struct rt2_hdr);

	return 0;
	}

	/*
	* Do nothing about destroying since it has no specific operation for routing
	* header type 2 unlike IPsec protocols.
	*/
	static void mip6_rthdr_destroy(struct xfrm_state *x)
	{
	}

	static const struct xfrm_type mip6_rthdr_type = {
	.owner = THIS_MODULE,
	.proto = IPPROTO_ROUTING,
	.flags = XFRM_TYPE_NON_FRAGMENT \| XFRM_TYPE_REMOTE_COADDR,
	.init_state = mip6_rthdr_init_state,
	.destructor = mip6_rthdr_destroy,
	.input = mip6_rthdr_input,
	.output = mip6_rthdr_output,
	};

	static int __init mip6_init(void)
	{
	pr_info("Mobile IPv6\n");

	if (xfrm_register_type(&mip6_destopt_type, AF_INET6) < 0) {
	pr_info("%s: can't add xfrm type(destopt)\n", __func__);
	goto mip6_destopt_xfrm_fail;
	}
	if (xfrm_register_type(&mip6_rthdr_type, AF_INET6) < 0) {
	pr_info("%s: can't add xfrm type(rthdr)\n", __func__);
	goto mip6_rthdr_xfrm_fail;
	}
	if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
	pr_info("%s: can't add rawv6 mh filter\n", __func__);
	goto mip6_rawv6_mh_fail;
	}


	return 0;

	mip6_rawv6_mh_fail:
	xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
	mip6_rthdr_xfrm_fail:
	xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
	mip6_destopt_xfrm_fail:
	return -EAGAIN;
	}

	static void __exit mip6_fini(void)
	{
	if (rawv6_mh_filter_unregister(mip6_mh_filter) < 0)
	pr_info("%s: can't remove rawv6 mh filter\n", __func__);
	xfrm_unregister_type(&mip6_rthdr_type, AF_INET6);
	xfrm_unregister_type(&mip6_destopt_type, AF_INET6);
	}

	module_init(mip6_init);
	module_exit(mip6_fini);

	MODULE_LICENSE("GPL");
	MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_DSTOPTS);
	MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_ROUTING);