net/ipv6/icmp.c - kernel/msm-4.19 - Gitiles

 /*
  *	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>

 #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>

 DEFINE_SNMP_STAT(struct icmpv6_mib, icmpv6_statistics) __read_mostly;
 EXPORT_SYMBOL(icmpv6_statistics);
 DEFINE_SNMP_STAT(struct icmpv6msg_mib, icmpv6msg_statistics) __read_mostly;
 EXPORT_SYMBOL(icmpv6msg_statistics);

 /*
  *	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 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, int code, int pos)
 {
 	icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos, skb->dev);
 	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;

 	if (len < 0)
 		return 1;

 	ptr = ipv6_skip_exthdr(skb, ptr, &nexthdr);
 	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 int icmpv6_xrlim_allow(struct sock *sk, int type,
 				     struct flowi *fl)
 {
 	struct dst_entry *dst;
 	struct net *net = sock_net(sk);
 	int res = 0;

 	/* Informational messages are not limited. */
 	if (type & ICMPV6_INFOMSG_MASK)
 		return 1;

 	/* Do not limit pmtu discovery, it would break it. */
 	if (type == ICMPV6_PKT_TOOBIG)
 		return 1;

 	/*
 	 * 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, fl);
 	if (dst->error) {
 		IP6_INC_STATS(net, ip6_dst_idev(dst),
 			      IPSTATS_MIB_OUTNOROUTES);
 	} else if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) {
 		res = 1;
 	} 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);

 		res = xrlim_allow(dst, 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 flowi *fl, 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((char *)icmp6h,
 					sizeof(struct icmp6hdr), skb->csum);
 		icmp6h->icmp6_cksum = csum_ipv6_magic(&fl->fl6_src,
 						      &fl->fl6_dst,
 						      len, fl->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((char *)icmp6h,
 					sizeof(struct icmp6hdr), tmp_csum);
 		icmp6h->icmp6_cksum = csum_ipv6_magic(&fl->fl6_src,
 						      &fl->fl6_dst,
 						      len, fl->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);
 			ipv6_addr_copy(&tmp, &iph->saddr);
 			ipv6_addr_copy(&iph->saddr, &hao->addr);
 			ipv6_addr_copy(&hao->addr, &tmp);
 		}
 	}
 }
 #else
 static inline void mip6_addr_swap(struct sk_buff *skb) {}
 #endif

 /*
  *	Send an ICMP message in response to a packet in error
  */
 void icmpv6_send(struct sk_buff *skb, int type, int code, __u32 info,
 		 struct net_device *dev)
 {
 	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;
 	struct in6_addr *saddr = NULL;
 	struct dst_entry *dst;
 	struct dst_entry *dst2;
 	struct icmp6hdr tmp_hdr;
 	struct flowi fl;
 	struct flowi fl2;
 	struct icmpv6_msg msg;
 	int iif = 0;
 	int addr_type = 0;
 	int len;
 	int hlimit, tclass;
 	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\n");
 		return;
 	}

 	/*
 	 *	Never answer to a ICMP packet.
 	 */
 	if (is_ineligible(skb)) {
 		LIMIT_NETDEBUG(KERN_DEBUG "icmpv6_send: no reply to icmp error\n");
 		return;
 	}

 	mip6_addr_swap(skb);

 	memset(&fl, 0, sizeof(fl));
 	fl.proto = IPPROTO_ICMPV6;
 	ipv6_addr_copy(&fl.fl6_dst, &hdr->saddr);
 	if (saddr)
 		ipv6_addr_copy(&fl.fl6_src, saddr);
 	fl.oif = iif;
 	fl.fl_icmp_type = type;
 	fl.fl_icmp_code = code;
 	security_skb_classify_flow(skb, &fl);

 	sk = icmpv6_xmit_lock(net);
 	if (sk == NULL)
 		return;
 	np = inet6_sk(sk);

 	if (!icmpv6_xrlim_allow(sk, type, &fl))
 		goto out;

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

 	if (!fl.oif && ipv6_addr_is_multicast(&fl.fl6_dst))
 		fl.oif = np->mcast_oif;

 	err = ip6_dst_lookup(sk, &dst, &fl);
 	if (err)
 		goto out;

 	/*
 	 * 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\n");
 		goto out_dst_release;
 	}

 	/* No need to clone since we're just using its address. */
 	dst2 = dst;

 	err = xfrm_lookup(&dst, &fl, sk, 0);
 	switch (err) {
 	case 0:
 		if (dst != dst2)
 			goto route_done;
 		break;
 	case -EPERM:
 		dst = NULL;
 		break;
 	default:
 		goto out;
 	}

 	if (xfrm_decode_session_reverse(skb, &fl2, AF_INET6))
 		goto relookup_failed;

 	if (ip6_dst_lookup(sk, &dst2, &fl))
 		goto relookup_failed;

 	err = xfrm_lookup(&dst2, &fl, sk, XFRM_LOOKUP_ICMP);
 	switch (err) {
 	case 0:
 		dst_release(dst);
 		dst = dst2;
 		break;
 	case -EPERM:
 		goto out_dst_release;
 	default:
 relookup_failed:
 		if (!dst)
 			goto out;
 		break;
 	}

 route_done:
 	if (ipv6_addr_is_multicast(&fl.fl6_dst))
 		hlimit = np->mcast_hops;
 	else
 		hlimit = np->hop_limit;
 	if (hlimit < 0)
 		hlimit = ip6_dst_hoplimit(dst);

 	tclass = np->tclass;
 	if (tclass < 0)
 		tclass = 0;

 	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\n");
 		goto out_dst_release;
 	}

 	idev = in6_dev_get(skb->dev);

 	err = ip6_append_data(sk, icmpv6_getfrag, &msg,
 			      len + sizeof(struct icmp6hdr),
 			      sizeof(struct icmp6hdr),
 			      hlimit, tclass, NULL, &fl, (struct rt6_info*)dst,
 			      MSG_DONTWAIT);
 	if (err) {
 		ip6_flush_pending_frames(sk);
 		goto out_put;
 	}
 	err = icmpv6_push_pending_frames(sk, &fl, &tmp_hdr, len + sizeof(struct icmp6hdr));

 out_put:
 	if (likely(idev != NULL))
 		in6_dev_put(idev);
 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;
 	struct in6_addr *saddr = NULL;
 	struct icmp6hdr *icmph = icmp6_hdr(skb);
 	struct icmp6hdr tmp_hdr;
 	struct flowi fl;
 	struct icmpv6_msg msg;
 	struct dst_entry *dst;
 	int err = 0;
 	int hlimit;
 	int tclass;

 	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(&fl, 0, sizeof(fl));
 	fl.proto = IPPROTO_ICMPV6;
 	ipv6_addr_copy(&fl.fl6_dst, &ipv6_hdr(skb)->saddr);
 	if (saddr)
 		ipv6_addr_copy(&fl.fl6_src, saddr);
 	fl.oif = skb->dev->ifindex;
 	fl.fl_icmp_type = ICMPV6_ECHO_REPLY;
 	security_skb_classify_flow(skb, &fl);

 	sk = icmpv6_xmit_lock(net);
 	if (sk == NULL)
 		return;
 	np = inet6_sk(sk);

 	if (!fl.oif && ipv6_addr_is_multicast(&fl.fl6_dst))
 		fl.oif = np->mcast_oif;

 	err = ip6_dst_lookup(sk, &dst, &fl);
 	if (err)
 		goto out;
 	if ((err = xfrm_lookup(&dst, &fl, sk, 0)) < 0)
 		goto out;

 	if (ipv6_addr_is_multicast(&fl.fl6_dst))
 		hlimit = np->mcast_hops;
 	else
 		hlimit = np->hop_limit;
 	if (hlimit < 0)
 		hlimit = ip6_dst_hoplimit(dst);

 	tclass = np->tclass;
 	if (tclass < 0)
 		tclass = 0;

 	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, tclass, NULL, &fl,
 				(struct rt6_info*)dst, MSG_DONTWAIT);

 	if (err) {
 		ip6_flush_pending_frames(sk);
 		goto out_put;
 	}
 	err = icmpv6_push_pending_frames(sk, &fl, &tmp_hdr, skb->len + sizeof(struct icmp6hdr));

 out_put:
 	if (likely(idev != NULL))
 		in6_dev_put(idev);
 	dst_release(dst);
 out:
 	icmpv6_xmit_unlock(sk);
 }

 static void icmpv6_notify(struct sk_buff *skb, int type, int code, __be32 info)
 {
 	struct inet6_protocol *ipprot;
 	int inner_offset;
 	int hash;
 	u8 nexthdr;

 	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);
 		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);
 	struct in6_addr *saddr, *daddr;
 	struct ipv6hdr *orig_hdr;
 	struct icmp6hdr *hdr;
 	int type;

 	if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 		int nh;

 		if (!(skb->sp && skb->sp->xvec[skb->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 [" NIP6_FMT " > " NIP6_FMT "]\n",
 				       NIP6(*saddr), NIP6(*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\n");

 		/* 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 flowi *fl,
 		      u8 type,
 		      const struct in6_addr *saddr,
 		      const struct in6_addr *daddr,
 		      int oif)
 {
 	memset(fl, 0, sizeof(*fl));
 	ipv6_addr_copy(&fl->fl6_src, saddr);
 	ipv6_addr_copy(&fl->fl6_dst, daddr);
 	fl->proto	 	= IPPROTO_ICMPV6;
 	fl->fl_icmp_type	= type;
 	fl->fl_icmp_code	= 0;
 	fl->oif			= oif;
 	security_sk_classify_flow(sk, fl);
 }

 /*
  * 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).\n",
 			       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 * ((64 * 1024) + sizeof(struct sk_buff)));
 	}
 	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\n");
 	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(int type, int 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[] = {
 	{
 		.ctl_name	= NET_IPV6_ICMP_RATELIMIT,
 		.procname	= "ratelimit",
 		.data		= &init_net.ipv6.sysctl.icmpv6_time,
 		.maxlen		= sizeof(int),
 		.mode		= 0644,
 		.proc_handler	= &proc_dointvec_ms_jiffies,
 		.strategy	= &sysctl_ms_jiffies
 	},
 	{ .ctl_name = 0 },
 };

 struct ctl_table *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
	/*
	* 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>

	#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>

	DEFINE_SNMP_STAT(struct icmpv6_mib, icmpv6_statistics) __read_mostly;
	EXPORT_SYMBOL(icmpv6_statistics);
	DEFINE_SNMP_STAT(struct icmpv6msg_mib, icmpv6msg_statistics) __read_mostly;
	EXPORT_SYMBOL(icmpv6msg_statistics);

	/*
	* 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 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, int code, int pos)
	{
	icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos, skb->dev);
	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;

	if (len < 0)
	return 1;

	ptr = ipv6_skip_exthdr(skb, ptr, &nexthdr);
	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 int icmpv6_xrlim_allow(struct sock *sk, int type,
	struct flowi *fl)
	{
	struct dst_entry *dst;
	struct net *net = sock_net(sk);
	int res = 0;

	/* Informational messages are not limited. */
	if (type & ICMPV6_INFOMSG_MASK)
	return 1;

	/* Do not limit pmtu discovery, it would break it. */
	if (type == ICMPV6_PKT_TOOBIG)
	return 1;

	/*
	* 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, fl);
	if (dst->error) {
	IP6_INC_STATS(net, ip6_dst_idev(dst),
	IPSTATS_MIB_OUTNOROUTES);
	} else if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) {
	res = 1;
	} 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);

	res = xrlim_allow(dst, 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 flowi fl, 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((char *)icmp6h,
	sizeof(struct icmp6hdr), skb->csum);
	icmp6h->icmp6_cksum = csum_ipv6_magic(&fl->fl6_src,
	&fl->fl6_dst,
	len, fl->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((char *)icmp6h,
	sizeof(struct icmp6hdr), tmp_csum);
	icmp6h->icmp6_cksum = csum_ipv6_magic(&fl->fl6_src,
	&fl->fl6_dst,
	len, fl->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);
	ipv6_addr_copy(&tmp, &iph->saddr);
	ipv6_addr_copy(&iph->saddr, &hao->addr);
	ipv6_addr_copy(&hao->addr, &tmp);
	}
	}
	}
	#else
	static inline void mip6_addr_swap(struct sk_buff *skb) {}
	#endif

	/*
	* Send an ICMP message in response to a packet in error
	*/
	void icmpv6_send(struct sk_buff *skb, int type, int code, __u32 info,
	struct net_device *dev)
	{
	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;
	struct in6_addr *saddr = NULL;
	struct dst_entry *dst;
	struct dst_entry *dst2;
	struct icmp6hdr tmp_hdr;
	struct flowi fl;
	struct flowi fl2;
	struct icmpv6_msg msg;
	int iif = 0;
	int addr_type = 0;
	int len;
	int hlimit, tclass;
	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\n");
	return;
	}

	/*
	* Never answer to a ICMP packet.
	*/
	if (is_ineligible(skb)) {
	LIMIT_NETDEBUG(KERN_DEBUG "icmpv6_send: no reply to icmp error\n");
	return;
	}

	mip6_addr_swap(skb);

	memset(&fl, 0, sizeof(fl));
	fl.proto = IPPROTO_ICMPV6;
	ipv6_addr_copy(&fl.fl6_dst, &hdr->saddr);
	if (saddr)
	ipv6_addr_copy(&fl.fl6_src, saddr);
	fl.oif = iif;
	fl.fl_icmp_type = type;
	fl.fl_icmp_code = code;
	security_skb_classify_flow(skb, &fl);

	sk = icmpv6_xmit_lock(net);
	if (sk == NULL)
	return;
	np = inet6_sk(sk);

	if (!icmpv6_xrlim_allow(sk, type, &fl))
	goto out;

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

	if (!fl.oif && ipv6_addr_is_multicast(&fl.fl6_dst))
	fl.oif = np->mcast_oif;

	err = ip6_dst_lookup(sk, &dst, &fl);
	if (err)
	goto out;

	/*
	* 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\n");
	goto out_dst_release;
	}

	/* No need to clone since we're just using its address. */
	dst2 = dst;

	err = xfrm_lookup(&dst, &fl, sk, 0);
	switch (err) {
	case 0:
	if (dst != dst2)
	goto route_done;
	break;
	case -EPERM:
	dst = NULL;
	break;
	default:
	goto out;
	}

	if (xfrm_decode_session_reverse(skb, &fl2, AF_INET6))
	goto relookup_failed;

	if (ip6_dst_lookup(sk, &dst2, &fl))
	goto relookup_failed;

	err = xfrm_lookup(&dst2, &fl, sk, XFRM_LOOKUP_ICMP);
	switch (err) {
	case 0:
	dst_release(dst);
	dst = dst2;
	break;
	case -EPERM:
	goto out_dst_release;
	default:
	relookup_failed:
	if (!dst)
	goto out;
	break;
	}

	route_done:
	if (ipv6_addr_is_multicast(&fl.fl6_dst))
	hlimit = np->mcast_hops;
	else
	hlimit = np->hop_limit;
	if (hlimit < 0)
	hlimit = ip6_dst_hoplimit(dst);

	tclass = np->tclass;
	if (tclass < 0)
	tclass = 0;

	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\n");
	goto out_dst_release;
	}

	idev = in6_dev_get(skb->dev);

	err = ip6_append_data(sk, icmpv6_getfrag, &msg,
	len + sizeof(struct icmp6hdr),
	sizeof(struct icmp6hdr),
	hlimit, tclass, NULL, &fl, (struct rt6_info*)dst,
	MSG_DONTWAIT);
	if (err) {
	ip6_flush_pending_frames(sk);
	goto out_put;
	}
	err = icmpv6_push_pending_frames(sk, &fl, &tmp_hdr, len + sizeof(struct icmp6hdr));

	out_put:
	if (likely(idev != NULL))
	in6_dev_put(idev);
	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;
	struct in6_addr *saddr = NULL;
	struct icmp6hdr *icmph = icmp6_hdr(skb);
	struct icmp6hdr tmp_hdr;
	struct flowi fl;
	struct icmpv6_msg msg;
	struct dst_entry *dst;
	int err = 0;
	int hlimit;
	int tclass;

	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(&fl, 0, sizeof(fl));
	fl.proto = IPPROTO_ICMPV6;
	ipv6_addr_copy(&fl.fl6_dst, &ipv6_hdr(skb)->saddr);
	if (saddr)
	ipv6_addr_copy(&fl.fl6_src, saddr);
	fl.oif = skb->dev->ifindex;
	fl.fl_icmp_type = ICMPV6_ECHO_REPLY;
	security_skb_classify_flow(skb, &fl);

	sk = icmpv6_xmit_lock(net);
	if (sk == NULL)
	return;
	np = inet6_sk(sk);

	if (!fl.oif && ipv6_addr_is_multicast(&fl.fl6_dst))
	fl.oif = np->mcast_oif;

	err = ip6_dst_lookup(sk, &dst, &fl);
	if (err)
	goto out;
	if ((err = xfrm_lookup(&dst, &fl, sk, 0)) < 0)
	goto out;

	if (ipv6_addr_is_multicast(&fl.fl6_dst))
	hlimit = np->mcast_hops;
	else
	hlimit = np->hop_limit;
	if (hlimit < 0)
	hlimit = ip6_dst_hoplimit(dst);

	tclass = np->tclass;
	if (tclass < 0)
	tclass = 0;

	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, tclass, NULL, &fl,
	(struct rt6_info*)dst, MSG_DONTWAIT);

	if (err) {
	ip6_flush_pending_frames(sk);
	goto out_put;
	}
	err = icmpv6_push_pending_frames(sk, &fl, &tmp_hdr, skb->len + sizeof(struct icmp6hdr));

	out_put:
	if (likely(idev != NULL))
	in6_dev_put(idev);
	dst_release(dst);
	out:
	icmpv6_xmit_unlock(sk);
	}

	static void icmpv6_notify(struct sk_buff *skb, int type, int code, __be32 info)
	{
	struct inet6_protocol *ipprot;
	int inner_offset;
	int hash;
	u8 nexthdr;

	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);
	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);
	struct in6_addr saddr, daddr;
	struct ipv6hdr *orig_hdr;
	struct icmp6hdr *hdr;
	int type;

	if (!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	int nh;

	if (!(skb->sp && skb->sp->xvec[skb->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 [" NIP6_FMT " > " NIP6_FMT "]\n",
	NIP6(saddr), NIP6(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\n");

	/* 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 flowi fl,
	u8 type,
	const struct in6_addr *saddr,
	const struct in6_addr *daddr,
	int oif)
	{
	memset(fl, 0, sizeof(*fl));
	ipv6_addr_copy(&fl->fl6_src, saddr);
	ipv6_addr_copy(&fl->fl6_dst, daddr);
	fl->proto = IPPROTO_ICMPV6;
	fl->fl_icmp_type = type;
	fl->fl_icmp_code = 0;
	fl->oif = oif;
	security_sk_classify_flow(sk, fl);
	}

	/*
	* 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).\n",
	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 * ((64 * 1024) + sizeof(struct sk_buff)));
	}
	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\n");
	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(int type, int 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[] = {
	{
	.ctl_name = NET_IPV6_ICMP_RATELIMIT,
	.procname = "ratelimit",
	.data = &init_net.ipv6.sysctl.icmpv6_time,
	.maxlen = sizeof(int),
	.mode = 0644,
	.proc_handler = &proc_dointvec_ms_jiffies,
	.strategy = &sysctl_ms_jiffies
	},
	{ .ctl_name = 0 },
	};

	struct ctl_table 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