net/ipv6/ip6_input.c - arm/linux - Git at Google

 /*
  *	IPv6 input
  *	Linux INET6 implementation
  *
  *	Authors:
  *	Pedro Roque		<roque@di.fc.ul.pt>
  *	Ian P. Morris		<I.P.Morris@soton.ac.uk>
  *
  *	Based in linux/net/ipv4/ip_input.c
  *
  *	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
  *
  *	Mitsuru KANDA @USAGI and
  *	YOSHIFUJI Hideaki @USAGI: Remove ipv6_parse_exthdrs().
  */

 #include <linux/errno.h>
 #include <linux/types.h>
 #include <linux/socket.h>
 #include <linux/sockios.h>
 #include <linux/net.h>
 #include <linux/netdevice.h>
 #include <linux/in6.h>
 #include <linux/icmpv6.h>
 #include <linux/mroute6.h>
 #include <linux/slab.h>

 #include <linux/netfilter.h>
 #include <linux/netfilter_ipv6.h>

 #include <net/sock.h>
 #include <net/snmp.h>

 #include <net/ipv6.h>
 #include <net/protocol.h>
 #include <net/transp_v6.h>
 #include <net/rawv6.h>
 #include <net/ndisc.h>
 #include <net/ip6_route.h>
 #include <net/addrconf.h>
 #include <net/xfrm.h>
 #include <net/inet_ecn.h>
 #include <net/dst_metadata.h>

 int ip6_rcv_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	void (*edemux)(struct sk_buff *skb);

 	/* if ingress device is enslaved to an L3 master device pass the
 	 * skb to its handler for processing
 	 */
 	skb = l3mdev_ip6_rcv(skb);
 	if (!skb)
 		return NET_RX_SUCCESS;

 	if (net->ipv4.sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) {
 		const struct inet6_protocol *ipprot;

 		ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
 		if (ipprot && (edemux = READ_ONCE(ipprot->early_demux)))
 			edemux(skb);
 	}
 	if (!skb_valid_dst(skb))
 		ip6_route_input(skb);

 	return dst_input(skb);
 }

 int ipv6_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
 {
 	const struct ipv6hdr *hdr;
 	u32 pkt_len;
 	struct inet6_dev *idev;
 	struct net *net = dev_net(skb->dev);

 	if (skb->pkt_type == PACKET_OTHERHOST) {
 		kfree_skb(skb);
 		return NET_RX_DROP;
 	}

 	rcu_read_lock();

 	idev = __in6_dev_get(skb->dev);

 	__IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_IN, skb->len);

 	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL ||
 	    !idev || unlikely(idev->cnf.disable_ipv6)) {
 		__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
 		goto drop;
 	}

 	memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));

 	/*
 	 * Store incoming device index. When the packet will
 	 * be queued, we cannot refer to skb->dev anymore.
 	 *
 	 * BTW, when we send a packet for our own local address on a
 	 * non-loopback interface (e.g. ethX), it is being delivered
 	 * via the loopback interface (lo) here; skb->dev = loopback_dev.
 	 * It, however, should be considered as if it is being
 	 * arrived via the sending interface (ethX), because of the
 	 * nature of scoping architecture. --yoshfuji
 	 */
 	IP6CB(skb)->iif = skb_valid_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;

 	if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
 		goto err;

 	hdr = ipv6_hdr(skb);

 	if (hdr->version != 6)
 		goto err;

 	__IP6_ADD_STATS(net, idev,
 			IPSTATS_MIB_NOECTPKTS +
 				(ipv6_get_dsfield(hdr) & INET_ECN_MASK),
 			max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
 	/*
 	 * RFC4291 2.5.3
 	 * The loopback address must not be used as the source address in IPv6
 	 * packets that are sent outside of a single node. [..]
 	 * A packet received on an interface with a destination address
 	 * of loopback must be dropped.
 	 */
 	if ((ipv6_addr_loopback(&hdr->saddr) ||
 	     ipv6_addr_loopback(&hdr->daddr)) &&
 	     !(dev->flags & IFF_LOOPBACK))
 		goto err;

 	/* RFC4291 Errata ID: 3480
 	 * Interface-Local scope spans only a single interface on a
 	 * node and is useful only for loopback transmission of
 	 * multicast.  Packets with interface-local scope received
 	 * from another node must be discarded.
 	 */
 	if (!(skb->pkt_type == PACKET_LOOPBACK ||
 	      dev->flags & IFF_LOOPBACK) &&
 	    ipv6_addr_is_multicast(&hdr->daddr) &&
 	    IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
 		goto err;

 	/* If enabled, drop unicast packets that were encapsulated in link-layer
 	 * multicast or broadcast to protected against the so-called "hole-196"
 	 * attack in 802.11 wireless.
 	 */
 	if (!ipv6_addr_is_multicast(&hdr->daddr) &&
 	    (skb->pkt_type == PACKET_BROADCAST ||
 	     skb->pkt_type == PACKET_MULTICAST) &&
 	    idev->cnf.drop_unicast_in_l2_multicast)
 		goto err;

 	/* RFC4291 2.7
 	 * Nodes must not originate a packet to a multicast address whose scope
 	 * field contains the reserved value 0; if such a packet is received, it
 	 * must be silently dropped.
 	 */
 	if (ipv6_addr_is_multicast(&hdr->daddr) &&
 	    IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
 		goto err;

 	/*
 	 * RFC4291 2.7
 	 * Multicast addresses must not be used as source addresses in IPv6
 	 * packets or appear in any Routing header.
 	 */
 	if (ipv6_addr_is_multicast(&hdr->saddr))
 		goto err;

 	skb->transport_header = skb->network_header + sizeof(*hdr);
 	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);

 	pkt_len = ntohs(hdr->payload_len);

 	/* pkt_len may be zero if Jumbo payload option is present */
 	if (pkt_len || hdr->nexthdr != NEXTHDR_HOP) {
 		if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
 			__IP6_INC_STATS(net,
 					idev, IPSTATS_MIB_INTRUNCATEDPKTS);
 			goto drop;
 		}
 		if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
 			__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 			goto drop;
 		}
 		hdr = ipv6_hdr(skb);
 	}

 	if (hdr->nexthdr == NEXTHDR_HOP) {
 		if (ipv6_parse_hopopts(skb) < 0) {
 			__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 			rcu_read_unlock();
 			return NET_RX_DROP;
 		}
 	}

 	rcu_read_unlock();

 	/* Must drop socket now because of tproxy. */
 	skb_orphan(skb);

 	return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
 		       net, NULL, skb, dev, NULL,
 		       ip6_rcv_finish);
 err:
 	__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 drop:
 	rcu_read_unlock();
 	kfree_skb(skb);
 	return NET_RX_DROP;
 }

 /*
  *	Deliver the packet to the host
  */


 static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
 {
 	const struct inet6_protocol *ipprot;
 	struct inet6_dev *idev;
 	unsigned int nhoff;
 	int nexthdr;
 	bool raw;
 	bool have_final = false;

 	/*
 	 *	Parse extension headers
 	 */

 	rcu_read_lock();
 resubmit:
 	idev = ip6_dst_idev(skb_dst(skb));
 	if (!pskb_pull(skb, skb_transport_offset(skb)))
 		goto discard;
 	nhoff = IP6CB(skb)->nhoff;
 	nexthdr = skb_network_header(skb)[nhoff];

 resubmit_final:
 	raw = raw6_local_deliver(skb, nexthdr);
 	ipprot = rcu_dereference(inet6_protos[nexthdr]);
 	if (ipprot) {
 		int ret;

 		if (have_final) {
 			if (!(ipprot->flags & INET6_PROTO_FINAL)) {
 				/* Once we've seen a final protocol don't
 				 * allow encapsulation on any non-final
 				 * ones. This allows foo in UDP encapsulation
 				 * to work.
 				 */
 				goto discard;
 			}
 		} else if (ipprot->flags & INET6_PROTO_FINAL) {
 			const struct ipv6hdr *hdr;

 			/* Only do this once for first final protocol */
 			have_final = true;

 			/* Free reference early: we don't need it any more,
 			   and it may hold ip_conntrack module loaded
 			   indefinitely. */
 			nf_reset(skb);

 			skb_postpull_rcsum(skb, skb_network_header(skb),
 					   skb_network_header_len(skb));
 			hdr = ipv6_hdr(skb);
 			if (ipv6_addr_is_multicast(&hdr->daddr) &&
 			    !ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
 			    &hdr->saddr) &&
 			    !ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb)))
 				goto discard;
 		}
 		if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
 		    !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
 			goto discard;

 		ret = ipprot->handler(skb);
 		if (ret > 0) {
 			if (ipprot->flags & INET6_PROTO_FINAL) {
 				/* Not an extension header, most likely UDP
 				 * encapsulation. Use return value as nexthdr
 				 * protocol not nhoff (which presumably is
 				 * not set by handler).
 				 */
 				nexthdr = ret;
 				goto resubmit_final;
 			} else {
 				goto resubmit;
 			}
 		} else if (ret == 0) {
 			__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
 		}
 	} else {
 		if (!raw) {
 			if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
 				__IP6_INC_STATS(net, idev,
 						IPSTATS_MIB_INUNKNOWNPROTOS);
 				icmpv6_send(skb, ICMPV6_PARAMPROB,
 					    ICMPV6_UNK_NEXTHDR, nhoff);
 			}
 			kfree_skb(skb);
 		} else {
 			__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
 			consume_skb(skb);
 		}
 	}
 	rcu_read_unlock();
 	return 0;

 discard:
 	__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
 	rcu_read_unlock();
 	kfree_skb(skb);
 	return 0;
 }


 int ip6_input(struct sk_buff *skb)
 {
 	return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN,
 		       dev_net(skb->dev), NULL, skb, skb->dev, NULL,
 		       ip6_input_finish);
 }
 EXPORT_SYMBOL_GPL(ip6_input);

 int ip6_mc_input(struct sk_buff *skb)
 {
 	const struct ipv6hdr *hdr;
 	bool deliver;

 	__IP6_UPD_PO_STATS(dev_net(skb_dst(skb)->dev),
 			 ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
 			 skb->len);

 	hdr = ipv6_hdr(skb);
 	deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);

 #ifdef CONFIG_IPV6_MROUTE
 	/*
 	 *      IPv6 multicast router mode is now supported ;)
 	 */
 	if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
 	    !(ipv6_addr_type(&hdr->daddr) &
 	      (IPV6_ADDR_LOOPBACK|IPV6_ADDR_LINKLOCAL)) &&
 	    likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
 		/*
 		 * Okay, we try to forward - split and duplicate
 		 * packets.
 		 */
 		struct sk_buff *skb2;
 		struct inet6_skb_parm *opt = IP6CB(skb);

 		/* Check for MLD */
 		if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
 			/* Check if this is a mld message */
 			u8 nexthdr = hdr->nexthdr;
 			__be16 frag_off;
 			int offset;

 			/* Check if the value of Router Alert
 			 * is for MLD (0x0000).
 			 */
 			if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
 				deliver = false;

 				if (!ipv6_ext_hdr(nexthdr)) {
 					/* BUG */
 					goto out;
 				}
 				offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
 							  &nexthdr, &frag_off);
 				if (offset < 0)
 					goto out;

 				if (ipv6_is_mld(skb, nexthdr, offset))
 					deliver = true;

 				goto out;
 			}
 			/* unknown RA - process it normally */
 		}

 		if (deliver)
 			skb2 = skb_clone(skb, GFP_ATOMIC);
 		else {
 			skb2 = skb;
 			skb = NULL;
 		}

 		if (skb2) {
 			ip6_mr_input(skb2);
 		}
 	}
 out:
 #endif
 	if (likely(deliver))
 		ip6_input(skb);
 	else {
 		/* discard */
 		kfree_skb(skb);
 	}

 	return 0;
 }
	/*
	* IPv6 input
	* Linux INET6 implementation
	*
	* Authors:
	* Pedro Roque <roque@di.fc.ul.pt>
	* Ian P. Morris <I.P.Morris@soton.ac.uk>
	*
	* Based in linux/net/ipv4/ip_input.c
	*
	* 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
	*
	* Mitsuru KANDA @USAGI and
	* YOSHIFUJI Hideaki @USAGI: Remove ipv6_parse_exthdrs().
	*/

	#include <linux/errno.h>
	#include <linux/types.h>
	#include <linux/socket.h>
	#include <linux/sockios.h>
	#include <linux/net.h>
	#include <linux/netdevice.h>
	#include <linux/in6.h>
	#include <linux/icmpv6.h>
	#include <linux/mroute6.h>
	#include <linux/slab.h>

	#include <linux/netfilter.h>
	#include <linux/netfilter_ipv6.h>

	#include <net/sock.h>
	#include <net/snmp.h>

	#include <net/ipv6.h>
	#include <net/protocol.h>
	#include <net/transp_v6.h>
	#include <net/rawv6.h>
	#include <net/ndisc.h>
	#include <net/ip6_route.h>
	#include <net/addrconf.h>
	#include <net/xfrm.h>
	#include <net/inet_ecn.h>
	#include <net/dst_metadata.h>

	int ip6_rcv_finish(struct net net, struct sock sk, struct sk_buff *skb)
	{
	void (edemux)(struct sk_buff skb);

	/* if ingress device is enslaved to an L3 master device pass the
	* skb to its handler for processing
	*/
	skb = l3mdev_ip6_rcv(skb);
	if (!skb)
	return NET_RX_SUCCESS;

	if (net->ipv4.sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) {
	const struct inet6_protocol *ipprot;

	ipprot = rcu_dereference(inet6_protos[ipv6_hdr(skb)->nexthdr]);
	if (ipprot && (edemux = READ_ONCE(ipprot->early_demux)))
	edemux(skb);
	}
	if (!skb_valid_dst(skb))
	ip6_route_input(skb);

	return dst_input(skb);
	}

	int ipv6_rcv(struct sk_buff skb, struct net_device dev, struct packet_type pt, struct net_device orig_dev)
	{
	const struct ipv6hdr *hdr;
	u32 pkt_len;
	struct inet6_dev *idev;
	struct net *net = dev_net(skb->dev);

	if (skb->pkt_type == PACKET_OTHERHOST) {
	kfree_skb(skb);
	return NET_RX_DROP;
	}

	rcu_read_lock();

	idev = __in6_dev_get(skb->dev);

	__IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_IN, skb->len);

	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL \|\|
	!idev \|\| unlikely(idev->cnf.disable_ipv6)) {
	__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
	goto drop;
	}

	memset(IP6CB(skb), 0, sizeof(struct inet6_skb_parm));

	/*
	* Store incoming device index. When the packet will
	* be queued, we cannot refer to skb->dev anymore.
	*
	* BTW, when we send a packet for our own local address on a
	* non-loopback interface (e.g. ethX), it is being delivered
	* via the loopback interface (lo) here; skb->dev = loopback_dev.
	* It, however, should be considered as if it is being
	* arrived via the sending interface (ethX), because of the
	* nature of scoping architecture. --yoshfuji
	*/
	IP6CB(skb)->iif = skb_valid_dst(skb) ? ip6_dst_idev(skb_dst(skb))->dev->ifindex : dev->ifindex;

	if (unlikely(!pskb_may_pull(skb, sizeof(*hdr))))
	goto err;

	hdr = ipv6_hdr(skb);

	if (hdr->version != 6)
	goto err;

	__IP6_ADD_STATS(net, idev,
	IPSTATS_MIB_NOECTPKTS +
	(ipv6_get_dsfield(hdr) & INET_ECN_MASK),
	max_t(unsigned short, 1, skb_shinfo(skb)->gso_segs));
	/*
	* RFC4291 2.5.3
	* The loopback address must not be used as the source address in IPv6
	* packets that are sent outside of a single node. [..]
	* A packet received on an interface with a destination address
	* of loopback must be dropped.
	*/
	if ((ipv6_addr_loopback(&hdr->saddr) \|\|
	ipv6_addr_loopback(&hdr->daddr)) &&
	!(dev->flags & IFF_LOOPBACK))
	goto err;

	/* RFC4291 Errata ID: 3480
	* Interface-Local scope spans only a single interface on a
	* node and is useful only for loopback transmission of
	* multicast. Packets with interface-local scope received
	* from another node must be discarded.
	*/
	if (!(skb->pkt_type == PACKET_LOOPBACK \|\|
	dev->flags & IFF_LOOPBACK) &&
	ipv6_addr_is_multicast(&hdr->daddr) &&
	IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 1)
	goto err;

	/* If enabled, drop unicast packets that were encapsulated in link-layer
	* multicast or broadcast to protected against the so-called "hole-196"
	* attack in 802.11 wireless.
	*/
	if (!ipv6_addr_is_multicast(&hdr->daddr) &&
	(skb->pkt_type == PACKET_BROADCAST \|\|
	skb->pkt_type == PACKET_MULTICAST) &&
	idev->cnf.drop_unicast_in_l2_multicast)
	goto err;

	/* RFC4291 2.7
	* Nodes must not originate a packet to a multicast address whose scope
	* field contains the reserved value 0; if such a packet is received, it
	* must be silently dropped.
	*/
	if (ipv6_addr_is_multicast(&hdr->daddr) &&
	IPV6_ADDR_MC_SCOPE(&hdr->daddr) == 0)
	goto err;

	/*
	* RFC4291 2.7
	* Multicast addresses must not be used as source addresses in IPv6
	* packets or appear in any Routing header.
	*/
	if (ipv6_addr_is_multicast(&hdr->saddr))
	goto err;

	skb->transport_header = skb->network_header + sizeof(*hdr);
	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);

	pkt_len = ntohs(hdr->payload_len);

	/* pkt_len may be zero if Jumbo payload option is present */
	if (pkt_len \|\| hdr->nexthdr != NEXTHDR_HOP) {
	if (pkt_len + sizeof(struct ipv6hdr) > skb->len) {
	__IP6_INC_STATS(net,
	idev, IPSTATS_MIB_INTRUNCATEDPKTS);
	goto drop;
	}
	if (pskb_trim_rcsum(skb, pkt_len + sizeof(struct ipv6hdr))) {
	__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
	goto drop;
	}
	hdr = ipv6_hdr(skb);
	}

	if (hdr->nexthdr == NEXTHDR_HOP) {
	if (ipv6_parse_hopopts(skb) < 0) {
	__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
	rcu_read_unlock();
	return NET_RX_DROP;
	}
	}

	rcu_read_unlock();

	/* Must drop socket now because of tproxy. */
	skb_orphan(skb);

	return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING,
	net, NULL, skb, dev, NULL,
	ip6_rcv_finish);
	err:
	__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
	drop:
	rcu_read_unlock();
	kfree_skb(skb);
	return NET_RX_DROP;
	}

	/*
	* Deliver the packet to the host
	*/


	static int ip6_input_finish(struct net net, struct sock sk, struct sk_buff *skb)
	{
	const struct inet6_protocol *ipprot;
	struct inet6_dev *idev;
	unsigned int nhoff;
	int nexthdr;
	bool raw;
	bool have_final = false;

	/*
	* Parse extension headers
	*/

	rcu_read_lock();
	resubmit:
	idev = ip6_dst_idev(skb_dst(skb));
	if (!pskb_pull(skb, skb_transport_offset(skb)))
	goto discard;
	nhoff = IP6CB(skb)->nhoff;
	nexthdr = skb_network_header(skb)[nhoff];

	resubmit_final:
	raw = raw6_local_deliver(skb, nexthdr);
	ipprot = rcu_dereference(inet6_protos[nexthdr]);
	if (ipprot) {
	int ret;

	if (have_final) {
	if (!(ipprot->flags & INET6_PROTO_FINAL)) {
	/* Once we've seen a final protocol don't
	* allow encapsulation on any non-final
	* ones. This allows foo in UDP encapsulation
	* to work.
	*/
	goto discard;
	}
	} else if (ipprot->flags & INET6_PROTO_FINAL) {
	const struct ipv6hdr *hdr;

	/* Only do this once for first final protocol */
	have_final = true;

	/* Free reference early: we don't need it any more,
	and it may hold ip_conntrack module loaded
	indefinitely. */
	nf_reset(skb);

	skb_postpull_rcsum(skb, skb_network_header(skb),
	skb_network_header_len(skb));
	hdr = ipv6_hdr(skb);
	if (ipv6_addr_is_multicast(&hdr->daddr) &&
	!ipv6_chk_mcast_addr(skb->dev, &hdr->daddr,
	&hdr->saddr) &&
	!ipv6_is_mld(skb, nexthdr, skb_network_header_len(skb)))
	goto discard;
	}
	if (!(ipprot->flags & INET6_PROTO_NOPOLICY) &&
	!xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb))
	goto discard;

	ret = ipprot->handler(skb);
	if (ret > 0) {
	if (ipprot->flags & INET6_PROTO_FINAL) {
	/* Not an extension header, most likely UDP
	* encapsulation. Use return value as nexthdr
	* protocol not nhoff (which presumably is
	* not set by handler).
	*/
	nexthdr = ret;
	goto resubmit_final;
	} else {
	goto resubmit;
	}
	} else if (ret == 0) {
	__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
	}
	} else {
	if (!raw) {
	if (xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) {
	__IP6_INC_STATS(net, idev,
	IPSTATS_MIB_INUNKNOWNPROTOS);
	icmpv6_send(skb, ICMPV6_PARAMPROB,
	ICMPV6_UNK_NEXTHDR, nhoff);
	}
	kfree_skb(skb);
	} else {
	__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDELIVERS);
	consume_skb(skb);
	}
	}
	rcu_read_unlock();
	return 0;

	discard:
	__IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
	rcu_read_unlock();
	kfree_skb(skb);
	return 0;
	}


	int ip6_input(struct sk_buff *skb)
	{
	return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN,
	dev_net(skb->dev), NULL, skb, skb->dev, NULL,
	ip6_input_finish);
	}
	EXPORT_SYMBOL_GPL(ip6_input);

	int ip6_mc_input(struct sk_buff *skb)
	{
	const struct ipv6hdr *hdr;
	bool deliver;

	__IP6_UPD_PO_STATS(dev_net(skb_dst(skb)->dev),
	ip6_dst_idev(skb_dst(skb)), IPSTATS_MIB_INMCAST,
	skb->len);

	hdr = ipv6_hdr(skb);
	deliver = ipv6_chk_mcast_addr(skb->dev, &hdr->daddr, NULL);

	#ifdef CONFIG_IPV6_MROUTE
	/*
	* IPv6 multicast router mode is now supported ;)
	*/
	if (dev_net(skb->dev)->ipv6.devconf_all->mc_forwarding &&
	!(ipv6_addr_type(&hdr->daddr) &
	(IPV6_ADDR_LOOPBACK\|IPV6_ADDR_LINKLOCAL)) &&
	likely(!(IP6CB(skb)->flags & IP6SKB_FORWARDED))) {
	/*
	* Okay, we try to forward - split and duplicate
	* packets.
	*/
	struct sk_buff *skb2;
	struct inet6_skb_parm *opt = IP6CB(skb);

	/* Check for MLD */
	if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
	/* Check if this is a mld message */
	u8 nexthdr = hdr->nexthdr;
	__be16 frag_off;
	int offset;

	/* Check if the value of Router Alert
	* is for MLD (0x0000).
	*/
	if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
	deliver = false;

	if (!ipv6_ext_hdr(nexthdr)) {
	/* BUG */
	goto out;
	}
	offset = ipv6_skip_exthdr(skb, sizeof(*hdr),
	&nexthdr, &frag_off);
	if (offset < 0)
	goto out;

	if (ipv6_is_mld(skb, nexthdr, offset))
	deliver = true;

	goto out;
	}
	/* unknown RA - process it normally */
	}

	if (deliver)
	skb2 = skb_clone(skb, GFP_ATOMIC);
	else {
	skb2 = skb;
	skb = NULL;
	}

	if (skb2) {
	ip6_mr_input(skb2);
	}
	}
	out:
	#endif
	if (likely(deliver))
	ip6_input(skb);
	else {
	/* discard */
	kfree_skb(skb);
	}

	return 0;
	}