/*
   *	Internet Control Message Protocol (ICMPv6)
   *	Linux INET6 implementation
   *
   *	Authors:
   *	Pedro Roque		<roque@di.fc.ul.pt>
   *

   *	Based on net/ipv4/icmp.c
   *
   *	RFC 1885
   *
   *	This program is free software; you can redistribute it and/or
   *      modify it under the terms of the GNU General Public License
   *      as published by the Free Software Foundation; either version
   *      2 of the License, or (at your option) any later version.
   */
  
  /*
   *	Changes:
   *
   *	Andi Kleen		:	exception handling
   *	Andi Kleen			add rate limits. never reply to a icmp.
   *					add more length checks and other fixes.
   *	yoshfuji		:	ensure to sent parameter problem for
   *					fragments.
   *	YOSHIFUJI Hideaki @USAGI:	added sysctl for icmp rate limit.
   *	Randy Dunlap and
   *	YOSHIFUJI Hideaki @USAGI:	Per-interface statistics support
   *	Kazunori MIYAZAWA @USAGI:       change output process to use ip6_append_data
   */
  
  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/socket.h>
  #include <linux/in.h>
  #include <linux/kernel.h>

  #include <linux/sockios.h>
  #include <linux/net.h>
  #include <linux/skbuff.h>
  #include <linux/init.h>

  #include <linux/netfilter.h>

  #include <linux/slab.h>

  
  #ifdef CONFIG_SYSCTL
  #include <linux/sysctl.h>
  #endif
  
  #include <linux/inet.h>
  #include <linux/netdevice.h>
  #include <linux/icmpv6.h>
  
  #include <net/ip.h>
  #include <net/sock.h>
  
  #include <net/ipv6.h>
  #include <net/ip6_checksum.h>
  #include <net/protocol.h>
  #include <net/raw.h>
  #include <net/rawv6.h>
  #include <net/transp_v6.h>
  #include <net/ip6_route.h>
  #include <net/addrconf.h>
  #include <net/icmp.h>

  #include <net/xfrm.h>

  #include <net/inet_common.h>

  
  #include <asm/uaccess.h>
  #include <asm/system.h>

  /*
   *	The ICMP socket(s). This is the most convenient way to flow control
   *	our ICMP output as well as maintain a clean interface throughout
   *	all layers. All Socketless IP sends will soon be gone.
   *
   *	On SMP we have one ICMP socket per-cpu.
   */

  static inline struct sock *icmpv6_sk(struct net *net)
  {
  	return net->ipv6.icmp_sk[smp_processor_id()];
  }

  static int icmpv6_rcv(struct sk_buff *skb);

  static const struct inet6_protocol icmpv6_protocol = {

  	.handler	=	icmpv6_rcv,

  	.flags		=	INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,

  };

  static __inline__ struct sock *icmpv6_xmit_lock(struct net *net)

  {

  	struct sock *sk;

  	local_bh_disable();

  	sk = icmpv6_sk(net);

  	if (unlikely(!spin_trylock(&sk->sk_lock.slock))) {

  		/* This can happen if the output path (f.e. SIT or
  		 * ip6ip6 tunnel) signals dst_link_failure() for an
  		 * outgoing ICMP6 packet.
  		 */
  		local_bh_enable();

  		return NULL;

  	}

  	return sk;

  }

  static __inline__ void icmpv6_xmit_unlock(struct sock *sk)

  {

  	spin_unlock_bh(&sk->sk_lock.slock);

  }

  /*

   * Slightly more convenient version of icmpv6_send.
   */

  void icmpv6_param_prob(struct sk_buff *skb, u8 code, int pos)

  {

  	icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos);

  	kfree_skb(skb);
  }
  
  /*
   * Figure out, may we reply to this packet with icmp error.
   *
   * We do not reply, if:
   *	- it was icmp error message.
   *	- it is truncated, so that it is known, that protocol is ICMPV6
   *	  (i.e. in the middle of some exthdr)
   *
   *	--ANK (980726)
   */
  
  static int is_ineligible(struct sk_buff *skb)
  {

  	int ptr = (u8 *)(ipv6_hdr(skb) + 1) - skb->data;

  	int len = skb->len - ptr;

  	__u8 nexthdr = ipv6_hdr(skb)->nexthdr;

  	__be16 frag_off;

  
  	if (len < 0)
  		return 1;

  	ptr = ipv6_skip_exthdr(skb, ptr, &nexthdr, &frag_off);

  	if (ptr < 0)
  		return 0;
  	if (nexthdr == IPPROTO_ICMPV6) {
  		u8 _type, *tp;
  		tp = skb_header_pointer(skb,
  			ptr+offsetof(struct icmp6hdr, icmp6_type),
  			sizeof(_type), &_type);
  		if (tp == NULL ||
  		    !(*tp & ICMPV6_INFOMSG_MASK))
  			return 1;
  	}
  	return 0;
  }

  /*
   * Check the ICMP output rate limit

   */

  static inline bool icmpv6_xrlim_allow(struct sock *sk, u8 type,

  				      struct flowi6 *fl6)

  {
  	struct dst_entry *dst;

  	struct net *net = sock_net(sk);

  	bool res = false;

  
  	/* Informational messages are not limited. */
  	if (type & ICMPV6_INFOMSG_MASK)

  		return true;

  
  	/* Do not limit pmtu discovery, it would break it. */
  	if (type == ICMPV6_PKT_TOOBIG)

  		return true;

  	/*

  	 * Look up the output route.
  	 * XXX: perhaps the expire for routing entries cloned by
  	 * this lookup should be more aggressive (not longer than timeout).
  	 */

  	dst = ip6_route_output(net, sk, fl6);

  	if (dst->error) {

  		IP6_INC_STATS(net, ip6_dst_idev(dst),

  			      IPSTATS_MIB_OUTNOROUTES);

  	} else if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) {

  		res = true;

  	} else {
  		struct rt6_info *rt = (struct rt6_info *)dst;

  		int tmo = net->ipv6.sysctl.icmpv6_time;

  
  		/* Give more bandwidth to wider prefixes. */
  		if (rt->rt6i_dst.plen < 128)
  			tmo >>= ((128 - rt->rt6i_dst.plen)>>5);

  		if (!rt->rt6i_peer)
  			rt6_bind_peer(rt, 1);
  		res = inet_peer_xrlim_allow(rt->rt6i_peer, tmo);

  	}
  	dst_release(dst);
  	return res;
  }
  
  /*
   *	an inline helper for the "simple" if statement below
   *	checks if parameter problem report is caused by an

   *	unrecognized IPv6 option that has the Option Type

   *	highest-order two bits set to 10
   */
  
  static __inline__ int opt_unrec(struct sk_buff *skb, __u32 offset)
  {
  	u8 _optval, *op;

  	offset += skb_network_offset(skb);

  	op = skb_header_pointer(skb, offset, sizeof(_optval), &_optval);
  	if (op == NULL)
  		return 1;
  	return (*op & 0xC0) == 0x80;
  }

  static int icmpv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6, struct icmp6hdr *thdr, int len)

  {
  	struct sk_buff *skb;
  	struct icmp6hdr *icmp6h;
  	int err = 0;
  
  	if ((skb = skb_peek(&sk->sk_write_queue)) == NULL)
  		goto out;

  	icmp6h = icmp6_hdr(skb);

  	memcpy(icmp6h, thdr, sizeof(struct icmp6hdr));
  	icmp6h->icmp6_cksum = 0;
  
  	if (skb_queue_len(&sk->sk_write_queue) == 1) {

  		skb->csum = csum_partial(icmp6h,

  					sizeof(struct icmp6hdr), skb->csum);

  		icmp6h->icmp6_cksum = csum_ipv6_magic(&fl6->saddr,
  						      &fl6->daddr,
  						      len, fl6->flowi6_proto,

  						      skb->csum);
  	} else {

  		__wsum tmp_csum = 0;

  
  		skb_queue_walk(&sk->sk_write_queue, skb) {
  			tmp_csum = csum_add(tmp_csum, skb->csum);
  		}

  		tmp_csum = csum_partial(icmp6h,

  					sizeof(struct icmp6hdr), tmp_csum);

  		icmp6h->icmp6_cksum = csum_ipv6_magic(&fl6->saddr,
  						      &fl6->daddr,
  						      len, fl6->flowi6_proto,

  						      tmp_csum);

  	}

  	ip6_push_pending_frames(sk);
  out:
  	return err;
  }
  
  struct icmpv6_msg {
  	struct sk_buff	*skb;
  	int		offset;

  	uint8_t		type;

  };
  
  static int icmpv6_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
  {
  	struct icmpv6_msg *msg = (struct icmpv6_msg *) from;
  	struct sk_buff *org_skb = msg->skb;

  	__wsum csum = 0;

  
  	csum = skb_copy_and_csum_bits(org_skb, msg->offset + offset,
  				      to, len, csum);
  	skb->csum = csum_block_add(skb->csum, csum, odd);

  	if (!(msg->type & ICMPV6_INFOMSG_MASK))
  		nf_ct_attach(skb, org_skb);

  	return 0;
  }

  #if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)

  static void mip6_addr_swap(struct sk_buff *skb)
  {

  	struct ipv6hdr *iph = ipv6_hdr(skb);

  	struct inet6_skb_parm *opt = IP6CB(skb);
  	struct ipv6_destopt_hao *hao;
  	struct in6_addr tmp;
  	int off;
  
  	if (opt->dsthao) {
  		off = ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO);
  		if (likely(off >= 0)) {

  			hao = (struct ipv6_destopt_hao *)
  					(skb_network_header(skb) + off);

  			tmp = iph->saddr;
  			iph->saddr = hao->addr;
  			hao->addr = tmp;

  		}
  	}
  }
  #else
  static inline void mip6_addr_swap(struct sk_buff *skb) {}
  #endif

  static struct dst_entry *icmpv6_route_lookup(struct net *net, struct sk_buff *skb,

  					     struct sock *sk, struct flowi6 *fl6)

  {
  	struct dst_entry *dst, *dst2;

  	struct flowi6 fl2;

  	int err;

  	err = ip6_dst_lookup(sk, &dst, fl6);

  	if (err)
  		return ERR_PTR(err);
  
  	/*
  	 * We won't send icmp if the destination is known
  	 * anycast.
  	 */
  	if (((struct rt6_info *)dst)->rt6i_flags & RTF_ANYCAST) {
  		LIMIT_NETDEBUG(KERN_DEBUG "icmpv6_send: acast source
  ");
  		dst_release(dst);
  		return ERR_PTR(-EINVAL);
  	}
  
  	/* No need to clone since we're just using its address. */
  	dst2 = dst;

  	dst = xfrm_lookup(net, dst, flowi6_to_flowi(fl6), sk, 0);

  	if (!IS_ERR(dst)) {

  		if (dst != dst2)
  			return dst;

  	} else {
  		if (PTR_ERR(dst) == -EPERM)
  			dst = NULL;
  		else
  			return dst;

  	}

  	err = xfrm_decode_session_reverse(skb, flowi6_to_flowi(&fl2), AF_INET6);

  	if (err)
  		goto relookup_failed;
  
  	err = ip6_dst_lookup(sk, &dst2, &fl2);
  	if (err)
  		goto relookup_failed;

  	dst2 = xfrm_lookup(net, dst2, flowi6_to_flowi(&fl2), sk, XFRM_LOOKUP_ICMP);

  	if (!IS_ERR(dst2)) {

  		dst_release(dst);
  		dst = dst2;

  	} else {
  		err = PTR_ERR(dst2);
  		if (err == -EPERM) {
  			dst_release(dst);
  			return dst2;
  		} else
  			goto relookup_failed;

  	}
  
  relookup_failed:
  	if (dst)
  		return dst;
  	return ERR_PTR(err);
  }

  /*
   *	Send an ICMP message in response to a packet in error
   */

  void icmpv6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info)

  {

  	struct net *net = dev_net(skb->dev);

  	struct inet6_dev *idev = NULL;

  	struct ipv6hdr *hdr = ipv6_hdr(skb);

  	struct sock *sk;
  	struct ipv6_pinfo *np;

  	const struct in6_addr *saddr = NULL;

  	struct dst_entry *dst;
  	struct icmp6hdr tmp_hdr;

  	struct flowi6 fl6;

  	struct icmpv6_msg msg;
  	int iif = 0;
  	int addr_type = 0;
  	int len;

  	int hlimit;

  	int err = 0;

  	if ((u8 *)hdr < skb->head ||
  	    (skb->network_header + sizeof(*hdr)) > skb->tail)

  		return;
  
  	/*

  	 *	Make sure we respect the rules

  	 *	i.e. RFC 1885 2.4(e)
  	 *	Rule (e.1) is enforced by not using icmpv6_send
  	 *	in any code that processes icmp errors.
  	 */
  	addr_type = ipv6_addr_type(&hdr->daddr);

  	if (ipv6_chk_addr(net, &hdr->daddr, skb->dev, 0))

  		saddr = &hdr->daddr;
  
  	/*
  	 *	Dest addr check
  	 */
  
  	if ((addr_type & IPV6_ADDR_MULTICAST || skb->pkt_type != PACKET_HOST)) {
  		if (type != ICMPV6_PKT_TOOBIG &&

  		    !(type == ICMPV6_PARAMPROB &&
  		      code == ICMPV6_UNK_OPTION &&

  		      (opt_unrec(skb, info))))
  			return;
  
  		saddr = NULL;
  	}
  
  	addr_type = ipv6_addr_type(&hdr->saddr);
  
  	/*
  	 *	Source addr check
  	 */
  
  	if (addr_type & IPV6_ADDR_LINKLOCAL)
  		iif = skb->dev->ifindex;
  
  	/*

  	 *	Must not send error if the source does not uniquely
  	 *	identify a single node (RFC2463 Section 2.4).
  	 *	We check unspecified / multicast addresses here,
  	 *	and anycast addresses will be checked later.

  	 */
  	if ((addr_type == IPV6_ADDR_ANY) || (addr_type & IPV6_ADDR_MULTICAST)) {

  		LIMIT_NETDEBUG(KERN_DEBUG "icmpv6_send: addr_any/mcast source
  ");

  		return;
  	}

  	/*

  	 *	Never answer to a ICMP packet.
  	 */
  	if (is_ineligible(skb)) {

  		LIMIT_NETDEBUG(KERN_DEBUG "icmpv6_send: no reply to icmp error
  ");

  		return;
  	}

  	mip6_addr_swap(skb);

  	memset(&fl6, 0, sizeof(fl6));
  	fl6.flowi6_proto = IPPROTO_ICMPV6;

  	fl6.daddr = hdr->saddr;

  	if (saddr)

  		fl6.saddr = *saddr;

  	fl6.flowi6_oif = iif;

  	fl6.fl6_icmp_type = type;
  	fl6.fl6_icmp_code = code;

  	security_skb_classify_flow(skb, flowi6_to_flowi(&fl6));

  	sk = icmpv6_xmit_lock(net);
  	if (sk == NULL)

  		return;

  	np = inet6_sk(sk);

  	if (!icmpv6_xrlim_allow(sk, type, &fl6))

  		goto out;
  
  	tmp_hdr.icmp6_type = type;
  	tmp_hdr.icmp6_code = code;
  	tmp_hdr.icmp6_cksum = 0;
  	tmp_hdr.icmp6_pointer = htonl(info);

  	if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
  		fl6.flowi6_oif = np->mcast_oif;

  	dst = icmpv6_route_lookup(net, skb, sk, &fl6);

  	if (IS_ERR(dst))

  		goto out;

  	if (ipv6_addr_is_multicast(&fl6.daddr))

  		hlimit = np->mcast_hops;
  	else
  		hlimit = np->hop_limit;
  	if (hlimit < 0)

  		hlimit = ip6_dst_hoplimit(dst);

  
  	msg.skb = skb;

  	msg.offset = skb_network_offset(skb);

  	msg.type = type;

  
  	len = skb->len - msg.offset;
  	len = min_t(unsigned int, len, IPV6_MIN_MTU - sizeof(struct ipv6hdr) -sizeof(struct icmp6hdr));
  	if (len < 0) {

  		LIMIT_NETDEBUG(KERN_DEBUG "icmp: len problem
  ");

  		goto out_dst_release;
  	}

  	rcu_read_lock();
  	idev = __in6_dev_get(skb->dev);

  
  	err = ip6_append_data(sk, icmpv6_getfrag, &msg,
  			      len + sizeof(struct icmp6hdr),

  			      sizeof(struct icmp6hdr), hlimit,

  			      np->tclass, NULL, &fl6, (struct rt6_info*)dst,

  			      MSG_DONTWAIT, np->dontfrag);

  	if (err) {

  		ICMP6_INC_STATS_BH(net, idev, ICMP6_MIB_OUTERRORS);

  		ip6_flush_pending_frames(sk);

  	} else {
  		err = icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr,
  						 len + sizeof(struct icmp6hdr));

  	}

  	rcu_read_unlock();

  out_dst_release:
  	dst_release(dst);
  out:

  	icmpv6_xmit_unlock(sk);

  }

  EXPORT_SYMBOL(icmpv6_send);

  static void icmpv6_echo_reply(struct sk_buff *skb)
  {

  	struct net *net = dev_net(skb->dev);

  	struct sock *sk;

  	struct inet6_dev *idev;

  	struct ipv6_pinfo *np;

  	const struct in6_addr *saddr = NULL;

  	struct icmp6hdr *icmph = icmp6_hdr(skb);

  	struct icmp6hdr tmp_hdr;

  	struct flowi6 fl6;

  	struct icmpv6_msg msg;
  	struct dst_entry *dst;
  	int err = 0;
  	int hlimit;

  	saddr = &ipv6_hdr(skb)->daddr;

  
  	if (!ipv6_unicast_destination(skb))
  		saddr = NULL;
  
  	memcpy(&tmp_hdr, icmph, sizeof(tmp_hdr));
  	tmp_hdr.icmp6_type = ICMPV6_ECHO_REPLY;

  	memset(&fl6, 0, sizeof(fl6));
  	fl6.flowi6_proto = IPPROTO_ICMPV6;

  	fl6.daddr = ipv6_hdr(skb)->saddr;

  	if (saddr)

  		fl6.saddr = *saddr;

  	fl6.flowi6_oif = skb->dev->ifindex;

  	fl6.fl6_icmp_type = ICMPV6_ECHO_REPLY;

  	security_skb_classify_flow(skb, flowi6_to_flowi(&fl6));

  	sk = icmpv6_xmit_lock(net);
  	if (sk == NULL)

  		return;

  	np = inet6_sk(sk);

  	if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
  		fl6.flowi6_oif = np->mcast_oif;

  	err = ip6_dst_lookup(sk, &dst, &fl6);

  	if (err)
  		goto out;

  	dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0);

  	if (IS_ERR(dst))

  		goto out;

  	if (ipv6_addr_is_multicast(&fl6.daddr))

  		hlimit = np->mcast_hops;
  	else
  		hlimit = np->hop_limit;
  	if (hlimit < 0)

  		hlimit = ip6_dst_hoplimit(dst);

  	idev = __in6_dev_get(skb->dev);

  
  	msg.skb = skb;
  	msg.offset = 0;

  	msg.type = ICMPV6_ECHO_REPLY;

  
  	err = ip6_append_data(sk, icmpv6_getfrag, &msg, skb->len + sizeof(struct icmp6hdr),

  				sizeof(struct icmp6hdr), hlimit, np->tclass, NULL, &fl6,

  				(struct rt6_info*)dst, MSG_DONTWAIT,
  				np->dontfrag);

  
  	if (err) {

  		ICMP6_INC_STATS_BH(net, idev, ICMP6_MIB_OUTERRORS);

  		ip6_flush_pending_frames(sk);

  	} else {
  		err = icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr,
  						 skb->len + sizeof(struct icmp6hdr));

  	}

  	dst_release(dst);

  out:

  	icmpv6_xmit_unlock(sk);

  }

  static void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)

  {

  	const struct inet6_protocol *ipprot;

  	int inner_offset;
  	int hash;
  	u8 nexthdr;

  	__be16 frag_off;

  
  	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
  		return;
  
  	nexthdr = ((struct ipv6hdr *)skb->data)->nexthdr;
  	if (ipv6_ext_hdr(nexthdr)) {
  		/* now skip over extension headers */

  		inner_offset = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
  						&nexthdr, &frag_off);

  		if (inner_offset<0)
  			return;
  	} else {
  		inner_offset = sizeof(struct ipv6hdr);
  	}
  
  	/* Checkin header including 8 bytes of inner protocol header. */
  	if (!pskb_may_pull(skb, inner_offset+8))
  		return;

  	/* BUGGG_FUTURE: we should try to parse exthdrs in this packet.
  	   Without this we will not able f.e. to make source routed
  	   pmtu discovery.
  	   Corresponding argument (opt) to notifiers is already added.
  	   --ANK (980726)
  	 */
  
  	hash = nexthdr & (MAX_INET_PROTOS - 1);
  
  	rcu_read_lock();
  	ipprot = rcu_dereference(inet6_protos[hash]);
  	if (ipprot && ipprot->err_handler)
  		ipprot->err_handler(skb, NULL, type, code, inner_offset, info);
  	rcu_read_unlock();

  	raw6_icmp_error(skb, nexthdr, type, code, inner_offset, info);

  }

  /*
   *	Handle icmp messages
   */

  static int icmpv6_rcv(struct sk_buff *skb)

  {

  	struct net_device *dev = skb->dev;
  	struct inet6_dev *idev = __in6_dev_get(dev);

  	const struct in6_addr *saddr, *daddr;
  	const struct ipv6hdr *orig_hdr;

  	struct icmp6hdr *hdr;

  	u8 type;

  	if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {

  		struct sec_path *sp = skb_sec_path(skb);

  		int nh;

  		if (!(sp && sp->xvec[sp->len - 1]->props.flags &

  				 XFRM_STATE_ICMP))
  			goto drop_no_count;

  		if (!pskb_may_pull(skb, sizeof(*hdr) + sizeof(*orig_hdr)))
  			goto drop_no_count;
  
  		nh = skb_network_offset(skb);
  		skb_set_network_header(skb, sizeof(*hdr));
  
  		if (!xfrm6_policy_check_reverse(NULL, XFRM_POLICY_IN, skb))
  			goto drop_no_count;
  
  		skb_set_network_header(skb, nh);
  	}

  	ICMP6_INC_STATS_BH(dev_net(dev), idev, ICMP6_MIB_INMSGS);

  	saddr = &ipv6_hdr(skb)->saddr;
  	daddr = &ipv6_hdr(skb)->daddr;

  
  	/* Perform checksum. */

  	switch (skb->ip_summed) {

  	case CHECKSUM_COMPLETE:

  		if (!csum_ipv6_magic(saddr, daddr, skb->len, IPPROTO_ICMPV6,
  				     skb->csum))
  			break;
  		/* fall through */
  	case CHECKSUM_NONE:

  		skb->csum = ~csum_unfold(csum_ipv6_magic(saddr, daddr, skb->len,
  					     IPPROTO_ICMPV6, 0));

  		if (__skb_checksum_complete(skb)) {

  			LIMIT_NETDEBUG(KERN_DEBUG "ICMPv6 checksum failed [%pI6 > %pI6]
  ",

  				       saddr, daddr);

  			goto discard_it;
  		}
  	}

  	if (!pskb_pull(skb, sizeof(*hdr)))
  		goto discard_it;

  	hdr = icmp6_hdr(skb);

  
  	type = hdr->icmp6_type;

  	ICMP6MSGIN_INC_STATS_BH(dev_net(dev), idev, type);

  
  	switch (type) {
  	case ICMPV6_ECHO_REQUEST:
  		icmpv6_echo_reply(skb);
  		break;
  
  	case ICMPV6_ECHO_REPLY:
  		/* we couldn't care less */
  		break;
  
  	case ICMPV6_PKT_TOOBIG:
  		/* BUGGG_FUTURE: if packet contains rthdr, we cannot update
  		   standard destination cache. Seems, only "advanced"
  		   destination cache will allow to solve this problem
  		   --ANK (980726)
  		 */
  		if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
  			goto discard_it;

  		hdr = icmp6_hdr(skb);

  		orig_hdr = (struct ipv6hdr *) (hdr + 1);
  		rt6_pmtu_discovery(&orig_hdr->daddr, &orig_hdr->saddr, dev,
  				   ntohl(hdr->icmp6_mtu));
  
  		/*
  		 *	Drop through to notify
  		 */
  
  	case ICMPV6_DEST_UNREACH:
  	case ICMPV6_TIME_EXCEED:
  	case ICMPV6_PARAMPROB:
  		icmpv6_notify(skb, type, hdr->icmp6_code, hdr->icmp6_mtu);
  		break;
  
  	case NDISC_ROUTER_SOLICITATION:
  	case NDISC_ROUTER_ADVERTISEMENT:
  	case NDISC_NEIGHBOUR_SOLICITATION:
  	case NDISC_NEIGHBOUR_ADVERTISEMENT:
  	case NDISC_REDIRECT:
  		ndisc_rcv(skb);
  		break;
  
  	case ICMPV6_MGM_QUERY:
  		igmp6_event_query(skb);
  		break;
  
  	case ICMPV6_MGM_REPORT:
  		igmp6_event_report(skb);
  		break;
  
  	case ICMPV6_MGM_REDUCTION:
  	case ICMPV6_NI_QUERY:
  	case ICMPV6_NI_REPLY:
  	case ICMPV6_MLD2_REPORT:
  	case ICMPV6_DHAAD_REQUEST:
  	case ICMPV6_DHAAD_REPLY:
  	case ICMPV6_MOBILE_PREFIX_SOL:
  	case ICMPV6_MOBILE_PREFIX_ADV:
  		break;
  
  	default:

  		LIMIT_NETDEBUG(KERN_DEBUG "icmpv6: msg of unknown type
  ");

  
  		/* informational */
  		if (type & ICMPV6_INFOMSG_MASK)
  			break;

  		/*
  		 * error of unknown type.
  		 * must pass to upper level

  		 */
  
  		icmpv6_notify(skb, type, hdr->icmp6_code, hdr->icmp6_mtu);

  	}

  	kfree_skb(skb);
  	return 0;
  
  discard_it:

  	ICMP6_INC_STATS_BH(dev_net(dev), idev, ICMP6_MIB_INERRORS);

  drop_no_count:

  	kfree_skb(skb);
  	return 0;
  }

  void icmpv6_flow_init(struct sock *sk, struct flowi6 *fl6,

  		      u8 type,
  		      const struct in6_addr *saddr,
  		      const struct in6_addr *daddr,
  		      int oif)
  {

  	memset(fl6, 0, sizeof(*fl6));

  	fl6->saddr = *saddr;
  	fl6->daddr = *daddr;

  	fl6->flowi6_proto 	= IPPROTO_ICMPV6;

  	fl6->fl6_icmp_type	= type;
  	fl6->fl6_icmp_code	= 0;

  	fl6->flowi6_oif		= oif;
  	security_sk_classify_flow(sk, flowi6_to_flowi(fl6));

  }

  /*

   * Special lock-class for __icmpv6_sk:

   */
  static struct lock_class_key icmpv6_socket_sk_dst_lock_key;

  static int __net_init icmpv6_sk_init(struct net *net)

  {
  	struct sock *sk;
  	int err, i, j;

  	net->ipv6.icmp_sk =
  		kzalloc(nr_cpu_ids * sizeof(struct sock *), GFP_KERNEL);
  	if (net->ipv6.icmp_sk == NULL)

  		return -ENOMEM;

  	for_each_possible_cpu(i) {

  		err = inet_ctl_sock_create(&sk, PF_INET6,
  					   SOCK_RAW, IPPROTO_ICMPV6, net);

  		if (err < 0) {
  			printk(KERN_ERR
  			       "Failed to initialize the ICMP6 control socket "
  			       "(err %d).
  ",
  			       err);
  			goto fail;
  		}

  		net->ipv6.icmp_sk[i] = sk;

  		/*
  		 * Split off their lock-class, because sk->sk_dst_lock
  		 * gets used from softirqs, which is safe for

  		 * __icmpv6_sk (because those never get directly used

  		 * via userspace syscalls), but unsafe for normal sockets.
  		 */
  		lockdep_set_class(&sk->sk_dst_lock,
  				  &icmpv6_socket_sk_dst_lock_key);

  
  		/* Enough space for 2 64K ICMP packets, including
  		 * sk_buff struct overhead.
  		 */

  		sk->sk_sndbuf = 2 * SKB_TRUESIZE(64 * 1024);

  	}

  	return 0;
  
   fail:

  	for (j = 0; j < i; j++)

  		inet_ctl_sock_destroy(net->ipv6.icmp_sk[j]);

  	kfree(net->ipv6.icmp_sk);

  	return err;
  }

  static void __net_exit icmpv6_sk_exit(struct net *net)

  {
  	int i;

  	for_each_possible_cpu(i) {

  		inet_ctl_sock_destroy(net->ipv6.icmp_sk[i]);

  	}

  	kfree(net->ipv6.icmp_sk);
  }

  static struct pernet_operations icmpv6_sk_ops = {

         .init = icmpv6_sk_init,
         .exit = icmpv6_sk_exit,
  };
  
  int __init icmpv6_init(void)
  {
  	int err;
  
  	err = register_pernet_subsys(&icmpv6_sk_ops);
  	if (err < 0)
  		return err;
  
  	err = -EAGAIN;
  	if (inet6_add_protocol(&icmpv6_protocol, IPPROTO_ICMPV6) < 0)
  		goto fail;
  	return 0;
  
  fail:
  	printk(KERN_ERR "Failed to register ICMP6 protocol
  ");
  	unregister_pernet_subsys(&icmpv6_sk_ops);
  	return err;
  }

  void icmpv6_cleanup(void)

  {
  	unregister_pernet_subsys(&icmpv6_sk_ops);

  	inet6_del_protocol(&icmpv6_protocol, IPPROTO_ICMPV6);
  }

  static const struct icmp6_err {

  	int err;
  	int fatal;
  } tab_unreach[] = {
  	{	/* NOROUTE */
  		.err	= ENETUNREACH,
  		.fatal	= 0,
  	},
  	{	/* ADM_PROHIBITED */
  		.err	= EACCES,
  		.fatal	= 1,
  	},
  	{	/* Was NOT_NEIGHBOUR, now reserved */
  		.err	= EHOSTUNREACH,
  		.fatal	= 0,
  	},
  	{	/* ADDR_UNREACH	*/
  		.err	= EHOSTUNREACH,
  		.fatal	= 0,
  	},
  	{	/* PORT_UNREACH	*/
  		.err	= ECONNREFUSED,
  		.fatal	= 1,
  	},
  };

  int icmpv6_err_convert(u8 type, u8 code, int *err)

  {
  	int fatal = 0;
  
  	*err = EPROTO;
  
  	switch (type) {
  	case ICMPV6_DEST_UNREACH:
  		fatal = 1;
  		if (code <= ICMPV6_PORT_UNREACH) {
  			*err  = tab_unreach[code].err;
  			fatal = tab_unreach[code].fatal;
  		}
  		break;
  
  	case ICMPV6_PKT_TOOBIG:
  		*err = EMSGSIZE;
  		break;

  	case ICMPV6_PARAMPROB:
  		*err = EPROTO;
  		fatal = 1;
  		break;
  
  	case ICMPV6_TIME_EXCEED:
  		*err = EHOSTUNREACH;
  		break;

  	}

  
  	return fatal;
  }

  EXPORT_SYMBOL(icmpv6_err_convert);

  #ifdef CONFIG_SYSCTL

  ctl_table ipv6_icmp_table_template[] = {

  	{

  		.procname	= "ratelimit",

  		.data		= &init_net.ipv6.sysctl.icmpv6_time,

  		.maxlen		= sizeof(int),
  		.mode		= 0644,

  		.proc_handler	= proc_dointvec_ms_jiffies,

  	},

  	{ },

  };

  struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net)

  {
  	struct ctl_table *table;
  
  	table = kmemdup(ipv6_icmp_table_template,
  			sizeof(ipv6_icmp_table_template),
  			GFP_KERNEL);

  
  	if (table)
  		table[0].data = &net->ipv6.sysctl.icmpv6_time;

  	return table;
  }

  #endif