text: /*
   *	Neighbour Discovery for IPv6
   *	Linux INET6 implementation
   *
   *	Authors:
   *	Pedro Roque		<roque@di.fc.ul.pt>
   *	Mike Shaver		<shaver@ingenia.com>
   *
   *	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:
   *
   *	Alexey I. Froloff		:	RFC6106 (DNSSL) support
   *	Pierre Ynard			:	export userland ND options
   *						through netlink (RDNSS support)
   *	Lars Fenneberg			:	fixed MTU setting on receipt
   *						of an RA.
   *	Janos Farkas			:	kmalloc failure checks
   *	Alexey Kuznetsov		:	state machine reworked
   *						and moved to net/core.
   *	Pekka Savola			:	RFC2461 validation
   *	YOSHIFUJI Hideaki @USAGI	:	Verify ND options properly
   */
  
  #define pr_fmt(fmt) "ICMPv6: " fmt
  
  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/socket.h>
  #include <linux/sockios.h>
  #include <linux/sched.h>
  #include <linux/net.h>
  #include <linux/in6.h>
  #include <linux/route.h>
  #include <linux/init.h>
  #include <linux/rcupdate.h>
  #include <linux/slab.h>
  #ifdef CONFIG_SYSCTL
  #include <linux/sysctl.h>
  #endif
  
  #include <linux/if_addr.h>
  #include <linux/if_arp.h>
  #include <linux/ipv6.h>
  #include <linux/icmpv6.h>
  #include <linux/jhash.h>
  
  #include <net/sock.h>
  #include <net/snmp.h>
  
  #include <net/ipv6.h>
  #include <net/protocol.h>
  #include <net/ndisc.h>
  #include <net/ip6_route.h>
  #include <net/addrconf.h>
  #include <net/icmp.h>
  
  #include <net/netlink.h>
  #include <linux/rtnetlink.h>
  
  #include <net/flow.h>
  #include <net/ip6_checksum.h>
  #include <net/inet_common.h>
  #include <linux/proc_fs.h>
  
  #include <linux/netfilter.h>
  #include <linux/netfilter_ipv6.h>
  
  /* Set to 3 to get tracing... */
  #define ND_DEBUG 1
  
  #define ND_PRINTK(val, level, fmt, ...)				\
  do {								\
  	if (val <= ND_DEBUG)					\
  		net_##level##_ratelimited(fmt, ##__VA_ARGS__);	\
  } while (0)
  
  static u32 ndisc_hash(const void *pkey,
  		      const struct net_device *dev,
  		      __u32 *hash_rnd);
  static int ndisc_constructor(struct neighbour *neigh);
  static void ndisc_solicit(struct neighbour *neigh, struct sk_buff *skb);
  static void ndisc_error_report(struct neighbour *neigh, struct sk_buff *skb);
  static int pndisc_constructor(struct pneigh_entry *n);
  static void pndisc_destructor(struct pneigh_entry *n);
  static void pndisc_redo(struct sk_buff *skb);
  
  static const struct neigh_ops ndisc_generic_ops = {
  	.family =		AF_INET6,
  	.solicit =		ndisc_solicit,
  	.error_report =		ndisc_error_report,
  	.output =		neigh_resolve_output,
  	.connected_output =	neigh_connected_output,
  };
  
  static const struct neigh_ops ndisc_hh_ops = {
  	.family =		AF_INET6,
  	.solicit =		ndisc_solicit,
  	.error_report =		ndisc_error_report,
  	.output =		neigh_resolve_output,
  	.connected_output =	neigh_resolve_output,
  };
  
  
  static const struct neigh_ops ndisc_direct_ops = {
  	.family =		AF_INET6,
  	.output =		neigh_direct_output,
  	.connected_output =	neigh_direct_output,
  };
  
  struct neigh_table nd_tbl = {
  	.family =	AF_INET6,
  	.key_len =	sizeof(struct in6_addr),
  	.hash =		ndisc_hash,
  	.constructor =	ndisc_constructor,
  	.pconstructor =	pndisc_constructor,
  	.pdestructor =	pndisc_destructor,
  	.proxy_redo =	pndisc_redo,
  	.id =		"ndisc_cache",
  	.parms = {
  		.tbl			= &nd_tbl,
  		.base_reachable_time	= ND_REACHABLE_TIME,
  		.retrans_time		= ND_RETRANS_TIMER,
  		.gc_staletime		= 60 * HZ,
  		.reachable_time		= ND_REACHABLE_TIME,
  		.delay_probe_time	= 5 * HZ,
  		.queue_len_bytes	= 64*1024,
  		.ucast_probes		= 3,
  		.mcast_probes		= 3,
  		.anycast_delay		= 1 * HZ,
  		.proxy_delay		= (8 * HZ) / 10,
  		.proxy_qlen		= 64,
  	},
  	.gc_interval =	  30 * HZ,
  	.gc_thresh1 =	 128,
  	.gc_thresh2 =	 512,
  	.gc_thresh3 =	1024,
  };
  
  static void ndisc_fill_addr_option(struct sk_buff *skb, int type, void *data)
  {
  	int pad   = ndisc_addr_option_pad(skb->dev->type);
  	int data_len = skb->dev->addr_len;
  	int space = ndisc_opt_addr_space(skb->dev);
  	u8 *opt = skb_put(skb, space);
  
  	opt[0] = type;
  	opt[1] = space>>3;
  
  	memset(opt + 2, 0, pad);
  	opt   += pad;
  	space -= pad;
  
  	memcpy(opt+2, data, data_len);
  	data_len += 2;
  	opt += data_len;
  	if ((space -= data_len) > 0)
  		memset(opt, 0, space);
  }
  
  static struct nd_opt_hdr *ndisc_next_option(struct nd_opt_hdr *cur,
  					    struct nd_opt_hdr *end)
  {
  	int type;
  	if (!cur || !end || cur >= end)
  		return NULL;
  	type = cur->nd_opt_type;
  	do {
  		cur = ((void *)cur) + (cur->nd_opt_len << 3);
  	} while(cur < end && cur->nd_opt_type != type);
  	return cur <= end && cur->nd_opt_type == type ? cur : NULL;
  }
  
  static inline int ndisc_is_useropt(struct nd_opt_hdr *opt)
  {
  	return opt->nd_opt_type == ND_OPT_RDNSS ||
  		opt->nd_opt_type == ND_OPT_DNSSL;
  }
  
  static struct nd_opt_hdr *ndisc_next_useropt(struct nd_opt_hdr *cur,
  					     struct nd_opt_hdr *end)
  {
  	if (!cur || !end || cur >= end)
  		return NULL;
  	do {
  		cur = ((void *)cur) + (cur->nd_opt_len << 3);
  	} while(cur < end && !ndisc_is_useropt(cur));
  	return cur <= end && ndisc_is_useropt(cur) ? cur : NULL;
  }
  
  struct ndisc_options *ndisc_parse_options(u8 *opt, int opt_len,
  					  struct ndisc_options *ndopts)
  {
  	struct nd_opt_hdr *nd_opt = (struct nd_opt_hdr *)opt;
  
  	if (!nd_opt || opt_len < 0 || !ndopts)
  		return NULL;
  	memset(ndopts, 0, sizeof(*ndopts));
  	while (opt_len) {
  		int l;
  		if (opt_len < sizeof(struct nd_opt_hdr))
  			return NULL;
  		l = nd_opt->nd_opt_len << 3;
  		if (opt_len < l || l == 0)
  			return NULL;
  		switch (nd_opt->nd_opt_type) {
  		case ND_OPT_SOURCE_LL_ADDR:
  		case ND_OPT_TARGET_LL_ADDR:
  		case ND_OPT_MTU:
  		case ND_OPT_REDIRECT_HDR:
  			if (ndopts->nd_opt_array[nd_opt->nd_opt_type]) {
  				ND_PRINTK(2, warn,
  					  "%s: duplicated ND6 option found: type=%d\n",
  					  __func__, nd_opt->nd_opt_type);
  			} else {
  				ndopts->nd_opt_array[nd_opt->nd_opt_type] = nd_opt;
  			}
  			break;
  		case ND_OPT_PREFIX_INFO:
  			ndopts->nd_opts_pi_end = nd_opt;
  			if (!ndopts->nd_opt_array[nd_opt->nd_opt_type])
  				ndopts->nd_opt_array[nd_opt->nd_opt_type] = nd_opt;
  			break;
  #ifdef CONFIG_IPV6_ROUTE_INFO
  		case ND_OPT_ROUTE_INFO:
  			ndopts->nd_opts_ri_end = nd_opt;
  			if (!ndopts->nd_opts_ri)
  				ndopts->nd_opts_ri = nd_opt;
  			break;
  #endif
  		default:
  			if (ndisc_is_useropt(nd_opt)) {
  				ndopts->nd_useropts_end = nd_opt;
  				if (!ndopts->nd_useropts)
  					ndopts->nd_useropts = nd_opt;
  			} else {
  				/*
  				 * Unknown options must be silently ignored,
  				 * to accommodate future extension to the
  				 * protocol.
  				 */
  				ND_PRINTK(2, notice,
  					  "%s: ignored unsupported option; type=%d, len=%d\n",
  					  __func__,
  					  nd_opt->nd_opt_type,
  					  nd_opt->nd_opt_len);
  			}
  		}
  		opt_len -= l;
  		nd_opt = ((void *)nd_opt) + l;
  	}
  	return ndopts;
  }
  
  int ndisc_mc_map(const struct in6_addr *addr, char *buf, struct net_device *dev, int dir)
  {
  	switch (dev->type) {
  	case ARPHRD_ETHER:
  	case ARPHRD_IEEE802:	/* Not sure. Check it later. --ANK */
  	case ARPHRD_FDDI:
  		ipv6_eth_mc_map(addr, buf);
  		return 0;
  	case ARPHRD_ARCNET:
  		ipv6_arcnet_mc_map(addr, buf);
  		return 0;
  	case ARPHRD_INFINIBAND:
  		ipv6_ib_mc_map(addr, dev->broadcast, buf);
  		return 0;
  	case ARPHRD_IPGRE:
  		return ipv6_ipgre_mc_map(addr, dev->broadcast, buf);
  	default:
  		if (dir) {
  			memcpy(buf, dev->broadcast, dev->addr_len);
  			return 0;
  		}
  	}
  	return -EINVAL;
  }
  
  EXPORT_SYMBOL(ndisc_mc_map);
  
  static u32 ndisc_hash(const void *pkey,
  		      const struct net_device *dev,
  		      __u32 *hash_rnd)
  {
  	return ndisc_hashfn(pkey, dev, hash_rnd);
  }
  
  static int ndisc_constructor(struct neighbour *neigh)
  {
  	struct in6_addr *addr = (struct in6_addr*)&neigh->primary_key;
  	struct net_device *dev = neigh->dev;
  	struct inet6_dev *in6_dev;
  	struct neigh_parms *parms;
  	bool is_multicast = ipv6_addr_is_multicast(addr);
  
  	in6_dev = in6_dev_get(dev);
  	if (in6_dev == NULL) {
  		return -EINVAL;
  	}
  
  	parms = in6_dev->nd_parms;
  	__neigh_parms_put(neigh->parms);
  	neigh->parms = neigh_parms_clone(parms);
  
  	neigh->type = is_multicast ? RTN_MULTICAST : RTN_UNICAST;
  	if (!dev->header_ops) {
  		neigh->nud_state = NUD_NOARP;
  		neigh->ops = &ndisc_direct_ops;
  		neigh->output = neigh_direct_output;
  	} else {
  		if (is_multicast) {
  			neigh->nud_state = NUD_NOARP;
  			ndisc_mc_map(addr, neigh->ha, dev, 1);
  		} else if (dev->flags&(IFF_NOARP|IFF_LOOPBACK)) {
  			neigh->nud_state = NUD_NOARP;
  			memcpy(neigh->ha, dev->dev_addr, dev->addr_len);
  			if (dev->flags&IFF_LOOPBACK)
  				neigh->type = RTN_LOCAL;
  		} else if (dev->flags&IFF_POINTOPOINT) {
  			neigh->nud_state = NUD_NOARP;
  			memcpy(neigh->ha, dev->broadcast, dev->addr_len);
  		}
  		if (dev->header_ops->cache)
  			neigh->ops = &ndisc_hh_ops;
  		else
  			neigh->ops = &ndisc_generic_ops;
  		if (neigh->nud_state&NUD_VALID)
  			neigh->output = neigh->ops->connected_output;
  		else
  			neigh->output = neigh->ops->output;
  	}
  	in6_dev_put(in6_dev);
  	return 0;
  }
  
  static int pndisc_constructor(struct pneigh_entry *n)
  {
  	struct in6_addr *addr = (struct in6_addr*)&n->key;
  	struct in6_addr maddr;
  	struct net_device *dev = n->dev;
  
  	if (dev == NULL || __in6_dev_get(dev) == NULL)
  		return -EINVAL;
  	addrconf_addr_solict_mult(addr, &maddr);
  	ipv6_dev_mc_inc(dev, &maddr);
  	return 0;
  }
  
  static void pndisc_destructor(struct pneigh_entry *n)
  {
  	struct in6_addr *addr = (struct in6_addr*)&n->key;
  	struct in6_addr maddr;
  	struct net_device *dev = n->dev;
  
  	if (dev == NULL || __in6_dev_get(dev) == NULL)
  		return;
  	addrconf_addr_solict_mult(addr, &maddr);
  	ipv6_dev_mc_dec(dev, &maddr);
  }
  
  static struct sk_buff *ndisc_alloc_skb(struct net_device *dev,
  				       int len)
  {
  	int hlen = LL_RESERVED_SPACE(dev);
  	int tlen = dev->needed_tailroom;
  	struct sock *sk = dev_net(dev)->ipv6.ndisc_sk;
  	struct sk_buff *skb;
  
  	skb = alloc_skb(hlen + sizeof(struct ipv6hdr) + len + tlen, GFP_ATOMIC);
  	if (!skb) {
  		ND_PRINTK(0, err, "ndisc: %s failed to allocate an skb\n",
  			  __func__);
  		return NULL;
  	}
  
  	skb->protocol = htons(ETH_P_IPV6);
  	skb->dev = dev;
  
  	skb_reserve(skb, hlen + sizeof(struct ipv6hdr));
  	skb_reset_transport_header(skb);
  
  	/* Manually assign socket ownership as we avoid calling
  	 * sock_alloc_send_pskb() to bypass wmem buffer limits
  	 */
  	skb_set_owner_w(skb, sk);
  
  	return skb;
  }
  
  static void ip6_nd_hdr(struct sk_buff *skb,
  		       const struct in6_addr *saddr,
  		       const struct in6_addr *daddr,
  		       int hop_limit, int len)
  {
  	struct ipv6hdr *hdr;
  
  	skb_push(skb, sizeof(*hdr));
  	skb_reset_network_header(skb);
  	hdr = ipv6_hdr(skb);
  
  	ip6_flow_hdr(hdr, 0, 0);
  
  	hdr->payload_len = htons(len);
  	hdr->nexthdr = IPPROTO_ICMPV6;
  	hdr->hop_limit = hop_limit;
  
  	hdr->saddr = *saddr;
  	hdr->daddr = *daddr;
  }
  
  static void ndisc_send_skb(struct sk_buff *skb,
  			   const struct in6_addr *daddr,
  			   const struct in6_addr *saddr)
  {
  	struct dst_entry *dst = skb_dst(skb);
  	struct net *net = dev_net(skb->dev);
  	struct sock *sk = net->ipv6.ndisc_sk;
  	struct inet6_dev *idev;
  	int err;
  	struct icmp6hdr *icmp6h = icmp6_hdr(skb);
  	u8 type;
  
  	type = icmp6h->icmp6_type;
  
  	if (!dst) {
  		struct sock *sk = net->ipv6.ndisc_sk;
  		struct flowi6 fl6;
  
  		icmpv6_flow_init(sk, &fl6, type, saddr, daddr, skb->dev->ifindex);
  		dst = icmp6_dst_alloc(skb->dev, &fl6);
  		if (IS_ERR(dst)) {
  			kfree_skb(skb);
  			return;
  		}
  
  		skb_dst_set(skb, dst);
  	}
  
  	icmp6h->icmp6_cksum = csum_ipv6_magic(saddr, daddr, skb->len,
  					      IPPROTO_ICMPV6,
  					      csum_partial(icmp6h,
  							   skb->len, 0));
  
  	ip6_nd_hdr(skb, saddr, daddr, inet6_sk(sk)->hop_limit, skb->len);
  
  	rcu_read_lock();
  	idev = __in6_dev_get(dst->dev);
  	IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len);
  
  	err = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, skb, NULL, dst->dev,
  		      dst_output);
  	if (!err) {
  		ICMP6MSGOUT_INC_STATS(net, idev, type);
  		ICMP6_INC_STATS(net, idev, ICMP6_MIB_OUTMSGS);
  	}
  
  	rcu_read_unlock();
  }
  
  static void ndisc_send_na(struct net_device *dev, struct neighbour *neigh,
  			  const struct in6_addr *daddr,
  			  const struct in6_addr *solicited_addr,
  			  bool router, bool solicited, bool override, bool inc_opt)
  {
  	struct sk_buff *skb;
  	struct in6_addr tmpaddr;
  	struct inet6_ifaddr *ifp;
  	const struct in6_addr *src_addr;
  	struct nd_msg *msg;
  	int optlen = 0;
  
  	/* for anycast or proxy, solicited_addr != src_addr */
  	ifp = ipv6_get_ifaddr(dev_net(dev), solicited_addr, dev, 1);
  	if (ifp) {
  		src_addr = solicited_addr;
  		if (ifp->flags & IFA_F_OPTIMISTIC)
  			override = 0;
  		inc_opt |= ifp->idev->cnf.force_tllao;
  		in6_ifa_put(ifp);
  	} else {
  		if (ipv6_dev_get_saddr(dev_net(dev), dev, daddr,
  				       inet6_sk(dev_net(dev)->ipv6.ndisc_sk)->srcprefs,
  				       &tmpaddr))
  			return;
  		src_addr = &tmpaddr;
  	}
  
  	if (!dev->addr_len)
  		inc_opt = 0;
  	if (inc_opt)
  		optlen += ndisc_opt_addr_space(dev);
  
  	skb = ndisc_alloc_skb(dev, sizeof(*msg) + optlen);
  	if (!skb)
  		return;
  
  	msg = (struct nd_msg *)skb_put(skb, sizeof(*msg));
  	*msg = (struct nd_msg) {
  		.icmph = {
  			.icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT,
  			.icmp6_router = router,
  			.icmp6_solicited = solicited,
  			.icmp6_override = override,
  		},
  		.target = *solicited_addr,
  	};
  
  	if (inc_opt)
  		ndisc_fill_addr_option(skb, ND_OPT_TARGET_LL_ADDR,
  				       dev->dev_addr);
  
  
  	ndisc_send_skb(skb, daddr, src_addr);
  }
  
  static void ndisc_send_unsol_na(struct net_device *dev)
  {
  	struct inet6_dev *idev;
  	struct inet6_ifaddr *ifa;
  
  	idev = in6_dev_get(dev);
  	if (!idev)
  		return;
  
  	read_lock_bh(&idev->lock);
  	list_for_each_entry(ifa, &idev->addr_list, if_list) {
  		ndisc_send_na(dev, NULL, &in6addr_linklocal_allnodes, &ifa->addr,
  			      /*router=*/ !!idev->cnf.forwarding,
  			      /*solicited=*/ false, /*override=*/ true,
  			      /*inc_opt=*/ true);
  	}
  	read_unlock_bh(&idev->lock);
  
  	in6_dev_put(idev);
  }
  
  void ndisc_send_ns(struct net_device *dev, struct neighbour *neigh,
  		   const struct in6_addr *solicit,
  		   const struct in6_addr *daddr, const struct in6_addr *saddr)
  {
  	struct sk_buff *skb;
  	struct in6_addr addr_buf;
  	int inc_opt = dev->addr_len;
  	int optlen = 0;
  	struct nd_msg *msg;
  
  	if (saddr == NULL) {
  		if (ipv6_get_lladdr(dev, &addr_buf,
  				   (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)))
  			return;
  		saddr = &addr_buf;
  	}
  
  	if (ipv6_addr_any(saddr))
  		inc_opt = 0;
  	if (inc_opt)
  		optlen += ndisc_opt_addr_space(dev);
  
  	skb = ndisc_alloc_skb(dev, sizeof(*msg) + optlen);
  	if (!skb)
  		return;
  
  	msg = (struct nd_msg *)skb_put(skb, sizeof(*msg));
  	*msg = (struct nd_msg) {
  		.icmph = {
  			.icmp6_type = NDISC_NEIGHBOUR_SOLICITATION,
  		},
  		.target = *solicit,
  	};
  
  	if (inc_opt)
  		ndisc_fill_addr_option(skb, ND_OPT_SOURCE_LL_ADDR,
  				       dev->dev_addr);
  
  	ndisc_send_skb(skb, daddr, saddr);
  }
  
  void ndisc_send_rs(struct net_device *dev, const struct in6_addr *saddr,
  		   const struct in6_addr *daddr)
  {
  	struct sk_buff *skb;
  	struct rs_msg *msg;
  	int send_sllao = dev->addr_len;
  	int optlen = 0;
  
  #ifdef CONFIG_IPV6_OPTIMISTIC_DAD
  	/*
  	 * According to section 2.2 of RFC 4429, we must not
  	 * send router solicitations with a sllao from
  	 * optimistic addresses, but we may send the solicitation
  	 * if we don't include the sllao.  So here we check
  	 * if our address is optimistic, and if so, we
  	 * suppress the inclusion of the sllao.
  	 */
  	if (send_sllao) {
  		struct inet6_ifaddr *ifp = ipv6_get_ifaddr(dev_net(dev), saddr,
  							   dev, 1);
  		if (ifp) {
  			if (ifp->flags & IFA_F_OPTIMISTIC)  {
  				send_sllao = 0;
  			}
  			in6_ifa_put(ifp);
  		} else {
  			send_sllao = 0;
  		}
  	}
  #endif
  	if (send_sllao)
  		optlen += ndisc_opt_addr_space(dev);
  
  	skb = ndisc_alloc_skb(dev, sizeof(*msg) + optlen);
  	if (!skb)
  		return;
  
  	msg = (struct rs_msg *)skb_put(skb, sizeof(*msg));
  	*msg = (struct rs_msg) {
  		.icmph = {
  			.icmp6_type = NDISC_ROUTER_SOLICITATION,
  		},
  	};
  
  	if (send_sllao)
  		ndisc_fill_addr_option(skb, ND_OPT_SOURCE_LL_ADDR,
  				       dev->dev_addr);
  
  	ndisc_send_skb(skb, daddr, saddr);
  }
  
  
  static void ndisc_error_report(struct neighbour *neigh, struct sk_buff *skb)
  {
  	/*
  	 *	"The sender MUST return an ICMP
  	 *	 destination unreachable"
  	 */
  	dst_link_failure(skb);
  	kfree_skb(skb);
  }
  
  /* Called with locked neigh: either read or both */
  
  static void ndisc_solicit(struct neighbour *neigh, struct sk_buff *skb)
  {
  	struct in6_addr *saddr = NULL;
  	struct in6_addr mcaddr;
  	struct net_device *dev = neigh->dev;
  	struct in6_addr *target = (struct in6_addr *)&neigh->primary_key;
  	int probes = atomic_read(&neigh->probes);
  
  	if (skb && ipv6_chk_addr(dev_net(dev), &ipv6_hdr(skb)->saddr, dev, 1))
  		saddr = &ipv6_hdr(skb)->saddr;
  
  	if ((probes -= neigh->parms->ucast_probes) < 0) {
  		if (!(neigh->nud_state & NUD_VALID)) {
  			ND_PRINTK(1, dbg,
  				  "%s: trying to ucast probe in NUD_INVALID: %pI6\n",
  				  __func__, target);
  		}
  		ndisc_send_ns(dev, neigh, target, target, saddr);
  	} else if ((probes -= neigh->parms->app_probes) < 0) {
  #ifdef CONFIG_ARPD
  		neigh_app_ns(neigh);
  #endif
  	} else {
  		addrconf_addr_solict_mult(target, &mcaddr);
  		ndisc_send_ns(dev, NULL, target, &mcaddr, saddr);
  	}
  }
  
  static int pndisc_is_router(const void *pkey,
  			    struct net_device *dev)
  {
  	struct pneigh_entry *n;
  	int ret = -1;
  
  	read_lock_bh(&nd_tbl.lock);
  	n = __pneigh_lookup(&nd_tbl, dev_net(dev), pkey, dev);
  	if (n)
  		ret = !!(n->flags & NTF_ROUTER);
  	read_unlock_bh(&nd_tbl.lock);
  
  	return ret;
  }
  
  static void ndisc_recv_ns(struct sk_buff *skb)
  {
  	struct nd_msg *msg = (struct nd_msg *)skb_transport_header(skb);
  	const struct in6_addr *saddr = &ipv6_hdr(skb)->saddr;
  	const struct in6_addr *daddr = &ipv6_hdr(skb)->daddr;
  	u8 *lladdr = NULL;
  	u32 ndoptlen = skb->tail - (skb->transport_header +
  				    offsetof(struct nd_msg, opt));
  	struct ndisc_options ndopts;
  	struct net_device *dev = skb->dev;
  	struct inet6_ifaddr *ifp;
  	struct inet6_dev *idev = NULL;
  	struct neighbour *neigh;
  	int dad = ipv6_addr_any(saddr);
  	bool inc;
  	int is_router = -1;
  
  	if (skb->len < sizeof(struct nd_msg)) {
  		ND_PRINTK(2, warn, "NS: packet too short\n");
  		return;
  	}
  
  	if (ipv6_addr_is_multicast(&msg->target)) {
  		ND_PRINTK(2, warn, "NS: multicast target address\n");
  		return;
  	}
  
  	/*
  	 * RFC2461 7.1.1:
  	 * DAD has to be destined for solicited node multicast address.
  	 */
  	if (dad && !ipv6_addr_is_solict_mult(daddr)) {
  		ND_PRINTK(2, warn, "NS: bad DAD packet (wrong destination)\n");
  		return;
  	}
  
  	if (!ndisc_parse_options(msg->opt, ndoptlen, &ndopts)) {
  		ND_PRINTK(2, warn, "NS: invalid ND options\n");
  		return;
  	}
  
  	if (ndopts.nd_opts_src_lladdr) {
  		lladdr = ndisc_opt_addr_data(ndopts.nd_opts_src_lladdr, dev);
  		if (!lladdr) {
  			ND_PRINTK(2, warn,
  				  "NS: invalid link-layer address length\n");
  			return;
  		}
  
  		/* RFC2461 7.1.1:
  		 *	If the IP source address is the unspecified address,
  		 *	there MUST NOT be source link-layer address option
  		 *	in the message.
  		 */
  		if (dad) {
  			ND_PRINTK(2, warn,
  				  "NS: bad DAD packet (link-layer address option)\n");
  			return;
  		}
  	}
  
  	inc = ipv6_addr_is_multicast(daddr);
  
  	ifp = ipv6_get_ifaddr(dev_net(dev), &msg->target, dev, 1);
  	if (ifp) {
  
  		if (ifp->flags & (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)) {
  			if (dad) {
  				/*
  				 * We are colliding with another node
  				 * who is doing DAD
  				 * so fail our DAD process
  				 */
  				addrconf_dad_failure(ifp);
  				return;
  			} else {
  				/*
  				 * This is not a dad solicitation.
  				 * If we are an optimistic node,
  				 * we should respond.
  				 * Otherwise, we should ignore it.
  				 */
  				if (!(ifp->flags & IFA_F_OPTIMISTIC))
  					goto out;
  			}
  		}
  
  		idev = ifp->idev;
  	} else {
  		struct net *net = dev_net(dev);
  
  		idev = in6_dev_get(dev);
  		if (!idev) {
  			/* XXX: count this drop? */
  			return;
  		}
  
  		if (ipv6_chk_acast_addr(net, dev, &msg->target) ||
  		    (idev->cnf.forwarding &&
  		     (net->ipv6.devconf_all->proxy_ndp || idev->cnf.proxy_ndp) &&
  		     (is_router = pndisc_is_router(&msg->target, dev)) >= 0)) {
  			if (!(NEIGH_CB(skb)->flags & LOCALLY_ENQUEUED) &&
  			    skb->pkt_type != PACKET_HOST &&
  			    inc != 0 &&
  			    idev->nd_parms->proxy_delay != 0) {
  				/*
  				 * for anycast or proxy,
  				 * sender should delay its response
  				 * by a random time between 0 and
  				 * MAX_ANYCAST_DELAY_TIME seconds.
  				 * (RFC2461) -- yoshfuji
  				 */
  				struct sk_buff *n = skb_clone(skb, GFP_ATOMIC);
  				if (n)
  					pneigh_enqueue(&nd_tbl, idev->nd_parms, n);
  				goto out;
  			}
  		} else
  			goto out;
  	}
  
  	if (is_router < 0)
  		is_router = idev->cnf.forwarding;
  
  	if (dad) {
  		ndisc_send_na(dev, NULL, &in6addr_linklocal_allnodes, &msg->target,
  			      !!is_router, false, (ifp != NULL), true);
  		goto out;
  	}
  
  	if (inc)
  		NEIGH_CACHE_STAT_INC(&nd_tbl, rcv_probes_mcast);
  	else
  		NEIGH_CACHE_STAT_INC(&nd_tbl, rcv_probes_ucast);
  
  	/*
  	 *	update / create cache entry
  	 *	for the source address
  	 */
  	neigh = __neigh_lookup(&nd_tbl, saddr, dev,
  			       !inc || lladdr || !dev->addr_len);
  	if (neigh)
  		neigh_update(neigh, lladdr, NUD_STALE,
  			     NEIGH_UPDATE_F_WEAK_OVERRIDE|
  			     NEIGH_UPDATE_F_OVERRIDE);
  	if (neigh || !dev->header_ops) {
  		ndisc_send_na(dev, neigh, saddr, &msg->target,
  			      !!is_router,
  			      true, (ifp != NULL && inc), inc);
  		if (neigh)
  			neigh_release(neigh);
  	}
  
  out:
  	if (ifp)
  		in6_ifa_put(ifp);
  	else
  		in6_dev_put(idev);
  }
  
  static void ndisc_recv_na(struct sk_buff *skb)
  {
  	struct nd_msg *msg = (struct nd_msg *)skb_transport_header(skb);
  	const struct in6_addr *saddr = &ipv6_hdr(skb)->saddr;
  	const struct in6_addr *daddr = &ipv6_hdr(skb)->daddr;
  	u8 *lladdr = NULL;
  	u32 ndoptlen = skb->tail - (skb->transport_header +
  				    offsetof(struct nd_msg, opt));
  	struct ndisc_options ndopts;
  	struct net_device *dev = skb->dev;
  	struct inet6_ifaddr *ifp;
  	struct neighbour *neigh;
  
  	if (skb->len < sizeof(struct nd_msg)) {
  		ND_PRINTK(2, warn, "NA: packet too short\n");
  		return;
  	}
  
  	if (ipv6_addr_is_multicast(&msg->target)) {
  		ND_PRINTK(2, warn, "NA: target address is multicast\n");
  		return;
  	}
  
  	if (ipv6_addr_is_multicast(daddr) &&
  	    msg->icmph.icmp6_solicited) {
  		ND_PRINTK(2, warn, "NA: solicited NA is multicasted\n");
  		return;
  	}
  
  	if (!ndisc_parse_options(msg->opt, ndoptlen, &ndopts)) {
  		ND_PRINTK(2, warn, "NS: invalid ND option\n");
  		return;
  	}
  	if (ndopts.nd_opts_tgt_lladdr) {
  		lladdr = ndisc_opt_addr_data(ndopts.nd_opts_tgt_lladdr, dev);
  		if (!lladdr) {
  			ND_PRINTK(2, warn,
  				  "NA: invalid link-layer address length\n");
  			return;
  		}
  	}
  	ifp = ipv6_get_ifaddr(dev_net(dev), &msg->target, dev, 1);
  	if (ifp) {
  		if (skb->pkt_type != PACKET_LOOPBACK
  		    && (ifp->flags & IFA_F_TENTATIVE)) {
  				addrconf_dad_failure(ifp);
  				return;
  		}
  		/* What should we make now? The advertisement
  		   is invalid, but ndisc specs say nothing
  		   about it. It could be misconfiguration, or
  		   an smart proxy agent tries to help us :-)
  
  		   We should not print the error if NA has been
  		   received from loopback - it is just our own
  		   unsolicited advertisement.
  		 */
  		if (skb->pkt_type != PACKET_LOOPBACK)
  			ND_PRINTK(1, warn,
  				  "NA: someone advertises our address %pI6 on %s!\n",
  				  &ifp->addr, ifp->idev->dev->name);
  		in6_ifa_put(ifp);
  		return;
  	}
  	neigh = neigh_lookup(&nd_tbl, &msg->target, dev);
  
  	if (neigh) {
  		u8 old_flags = neigh->flags;
  		struct net *net = dev_net(dev);
  
  		if (neigh->nud_state & NUD_FAILED)
  			goto out;
  
  		/*
  		 * Don't update the neighbor cache entry on a proxy NA from
  		 * ourselves because either the proxied node is off link or it
  		 * has already sent a NA to us.
  		 */
  		if (lladdr && !memcmp(lladdr, dev->dev_addr, dev->addr_len) &&
  		    net->ipv6.devconf_all->forwarding && net->ipv6.devconf_all->proxy_ndp &&
  		    pneigh_lookup(&nd_tbl, net, &msg->target, dev, 0)) {
  			/* XXX: idev->cnf.proxy_ndp */
  			goto out;
  		}
  
  		neigh_update(neigh, lladdr,
  			     msg->icmph.icmp6_solicited ? NUD_REACHABLE : NUD_STALE,
  			     NEIGH_UPDATE_F_WEAK_OVERRIDE|
  			     (msg->icmph.icmp6_override ? NEIGH_UPDATE_F_OVERRIDE : 0)|
  			     NEIGH_UPDATE_F_OVERRIDE_ISROUTER|
  			     (msg->icmph.icmp6_router ? NEIGH_UPDATE_F_ISROUTER : 0));
  
  		if ((old_flags & ~neigh->flags) & NTF_ROUTER) {
  			/*
  			 * Change: router to host
  			 */
  			struct rt6_info *rt;
  			rt = rt6_get_dflt_router(saddr, dev);
  			if (rt)
  				ip6_del_rt(rt);
  		}
  
  out:
  		neigh_release(neigh);
  	}
  }
  
  static void ndisc_recv_rs(struct sk_buff *skb)
  {
  	struct rs_msg *rs_msg = (struct rs_msg *)skb_transport_header(skb);
  	unsigned long ndoptlen = skb->len - sizeof(*rs_msg);
  	struct neighbour *neigh;
  	struct inet6_dev *idev;
  	const struct in6_addr *saddr = &ipv6_hdr(skb)->saddr;
  	struct ndisc_options ndopts;
  	u8 *lladdr = NULL;
  
  	if (skb->len < sizeof(*rs_msg))
  		return;
  
  	idev = __in6_dev_get(skb->dev);
  	if (!idev) {
  		ND_PRINTK(1, err, "RS: can't find in6 device\n");
  		return;
  	}
  
  	/* Don't accept RS if we're not in router mode */
  	if (!idev->cnf.forwarding)
  		goto out;
  
  	/*
  	 * Don't update NCE if src = ::;
  	 * this implies that the source node has no ip address assigned yet.
  	 */
  	if (ipv6_addr_any(saddr))
  		goto out;
  
  	/* Parse ND options */
  	if (!ndisc_parse_options(rs_msg->opt, ndoptlen, &ndopts)) {
  		ND_PRINTK(2, notice, "NS: invalid ND option, ignored\n");
  		goto out;
  	}
  
  	if (ndopts.nd_opts_src_lladdr) {
  		lladdr = ndisc_opt_addr_data(ndopts.nd_opts_src_lladdr,
  					     skb->dev);
  		if (!lladdr)
  			goto out;
  	}
  
  	neigh = __neigh_lookup(&nd_tbl, saddr, skb->dev, 1);
  	if (neigh) {
  		neigh_update(neigh, lladdr, NUD_STALE,
  			     NEIGH_UPDATE_F_WEAK_OVERRIDE|
  			     NEIGH_UPDATE_F_OVERRIDE|
  			     NEIGH_UPDATE_F_OVERRIDE_ISROUTER);
  		neigh_release(neigh);
  	}
  out:
  	return;
  }
  
  static void ndisc_ra_useropt(struct sk_buff *ra, struct nd_opt_hdr *opt)
  {
  	struct icmp6hdr *icmp6h = (struct icmp6hdr *)skb_transport_header(ra);
  	struct sk_buff *skb;
  	struct nlmsghdr *nlh;
  	struct nduseroptmsg *ndmsg;
  	struct net *net = dev_net(ra->dev);
  	int err;
  	int base_size = NLMSG_ALIGN(sizeof(struct nduseroptmsg)
  				    + (opt->nd_opt_len << 3));
  	size_t msg_size = base_size + nla_total_size(sizeof(struct in6_addr));
  
  	skb = nlmsg_new(msg_size, GFP_ATOMIC);
  	if (skb == NULL) {
  		err = -ENOBUFS;
  		goto errout;
  	}
  
  	nlh = nlmsg_put(skb, 0, 0, RTM_NEWNDUSEROPT, base_size, 0);
  	if (nlh == NULL) {
  		goto nla_put_failure;
  	}
  
  	ndmsg = nlmsg_data(nlh);
  	ndmsg->nduseropt_family = AF_INET6;
  	ndmsg->nduseropt_ifindex = ra->dev->ifindex;
  	ndmsg->nduseropt_icmp_type = icmp6h->icmp6_type;
  	ndmsg->nduseropt_icmp_code = icmp6h->icmp6_code;
  	ndmsg->nduseropt_opts_len = opt->nd_opt_len << 3;
  
  	memcpy(ndmsg + 1, opt, opt->nd_opt_len << 3);
  
  	if (nla_put(skb, NDUSEROPT_SRCADDR, sizeof(struct in6_addr),
  		    &ipv6_hdr(ra)->saddr))
  		goto nla_put_failure;
  	nlmsg_end(skb, nlh);
  
  	rtnl_notify(skb, net, 0, RTNLGRP_ND_USEROPT, NULL, GFP_ATOMIC);
  	return;
  
  nla_put_failure:
  	nlmsg_free(skb);
  	err = -EMSGSIZE;
  errout:
  	rtnl_set_sk_err(net, RTNLGRP_ND_USEROPT, err);
  }
  
  static void ndisc_router_discovery(struct sk_buff *skb)
  {
  	struct ra_msg *ra_msg = (struct ra_msg *)skb_transport_header(skb);
  	struct neighbour *neigh = NULL;
  	struct inet6_dev *in6_dev;
  	struct rt6_info *rt = NULL;
  	int lifetime;
  	struct ndisc_options ndopts;
  	int optlen;
  	unsigned int pref = 0;
  
  	__u8 * opt = (__u8 *)(ra_msg + 1);
  
  	optlen = (skb->tail - skb->transport_header) - sizeof(struct ra_msg);
  
  	if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL)) {
  		ND_PRINTK(2, warn, "RA: source address is not link-local\n");
  		return;
  	}
  	if (optlen < 0) {
  		ND_PRINTK(2, warn, "RA: packet too short\n");
  		return;
  	}
  
  #ifdef CONFIG_IPV6_NDISC_NODETYPE
  	if (skb->ndisc_nodetype == NDISC_NODETYPE_HOST) {
  		ND_PRINTK(2, warn, "RA: from host or unauthorized router\n");
  		return;
  	}
  #endif
  
  	/*
  	 *	set the RA_RECV flag in the interface
  	 */
  
  	in6_dev = __in6_dev_get(skb->dev);
  	if (in6_dev == NULL) {
  		ND_PRINTK(0, err, "RA: can't find inet6 device for %s\n",
  			  skb->dev->name);
  		return;
  	}
  
  	if (!ndisc_parse_options(opt, optlen, &ndopts)) {
  		ND_PRINTK(2, warn, "RA: invalid ND options\n");
  		return;
  	}
  
  	if (!ipv6_accept_ra(in6_dev))
  		goto skip_linkparms;
  
  #ifdef CONFIG_IPV6_NDISC_NODETYPE
  	/* skip link-specific parameters from interior routers */
  	if (skb->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT)
  		goto skip_linkparms;
  #endif
  
  	if (in6_dev->if_flags & IF_RS_SENT) {
  		/*
  		 *	flag that an RA was received after an RS was sent
  		 *	out on this interface.
  		 */
  		in6_dev->if_flags |= IF_RA_RCVD;
  	}
  
  	/*
  	 * Remember the managed/otherconf flags from most recently
  	 * received RA message (RFC 2462) -- yoshfuji
  	 */
  	in6_dev->if_flags = (in6_dev->if_flags & ~(IF_RA_MANAGED |
  				IF_RA_OTHERCONF)) |
  				(ra_msg->icmph.icmp6_addrconf_managed ?
  					IF_RA_MANAGED : 0) |
  				(ra_msg->icmph.icmp6_addrconf_other ?
  					IF_RA_OTHERCONF : 0);
  
  	if (!in6_dev->cnf.accept_ra_defrtr)
  		goto skip_defrtr;
  
  	if (ipv6_chk_addr(dev_net(in6_dev->dev), &ipv6_hdr(skb)->saddr, NULL, 0))
  		goto skip_defrtr;
  
  	lifetime = ntohs(ra_msg->icmph.icmp6_rt_lifetime);
  
  #ifdef CONFIG_IPV6_ROUTER_PREF
  	pref = ra_msg->icmph.icmp6_router_pref;
  	/* 10b is handled as if it were 00b (medium) */
  	if (pref == ICMPV6_ROUTER_PREF_INVALID ||
  	    !in6_dev->cnf.accept_ra_rtr_pref)
  		pref = ICMPV6_ROUTER_PREF_MEDIUM;
  #endif
  
  	rt = rt6_get_dflt_router(&ipv6_hdr(skb)->saddr, skb->dev);
  
  	if (rt) {
  		neigh = dst_neigh_lookup(&rt->dst, &ipv6_hdr(skb)->saddr);
  		if (!neigh) {
  			ND_PRINTK(0, err,
  				  "RA: %s got default router without neighbour\n",
  				  __func__);
  			ip6_rt_put(rt);
  			return;
  		}
  	}
  	if (rt && lifetime == 0) {
  		ip6_del_rt(rt);
  		rt = NULL;
  	}
  
  	if (rt == NULL && lifetime) {
  		ND_PRINTK(3, dbg, "RA: adding default router\n");
  
  		rt = rt6_add_dflt_router(&ipv6_hdr(skb)->saddr, skb->dev, pref);
  		if (rt == NULL) {
  			ND_PRINTK(0, err,
  				  "RA: %s failed to add default route\n",
  				  __func__);
  			return;
  		}
  
  		neigh = dst_neigh_lookup(&rt->dst, &ipv6_hdr(skb)->saddr);
  		if (neigh == NULL) {
  			ND_PRINTK(0, err,
  				  "RA: %s got default router without neighbour\n",
  				  __func__);
  			ip6_rt_put(rt);
  			return;
  		}
  		neigh->flags |= NTF_ROUTER;
  	} else if (rt) {
  		rt->rt6i_flags = (rt->rt6i_flags & ~RTF_PREF_MASK) | RTF_PREF(pref);
  	}
  
  	if (rt)
  		rt6_set_expires(rt, jiffies + (HZ * lifetime));
  	if (ra_msg->icmph.icmp6_hop_limit) {
  		in6_dev->cnf.hop_limit = ra_msg->icmph.icmp6_hop_limit;
  		if (rt)
  			dst_metric_set(&rt->dst, RTAX_HOPLIMIT,
  				       ra_msg->icmph.icmp6_hop_limit);
  	}
  
  skip_defrtr:
  
  	/*
  	 *	Update Reachable Time and Retrans Timer
  	 */
  
  	if (in6_dev->nd_parms) {
  		unsigned long rtime = ntohl(ra_msg->retrans_timer);
  
  		if (rtime && rtime/1000 < MAX_SCHEDULE_TIMEOUT/HZ) {
  			rtime = (rtime*HZ)/1000;
  			if (rtime < HZ/10)
  				rtime = HZ/10;
  			in6_dev->nd_parms->retrans_time = rtime;
  			in6_dev->tstamp = jiffies;
  			inet6_ifinfo_notify(RTM_NEWLINK, in6_dev);
  		}
  
  		rtime = ntohl(ra_msg->reachable_time);
  		if (rtime && rtime/1000 < MAX_SCHEDULE_TIMEOUT/(3*HZ)) {
  			rtime = (rtime*HZ)/1000;
  
  			if (rtime < HZ/10)
  				rtime = HZ/10;
  
  			if (rtime != in6_dev->nd_parms->base_reachable_time) {
  				in6_dev->nd_parms->base_reachable_time = rtime;
  				in6_dev->nd_parms->gc_staletime = 3 * rtime;
  				in6_dev->nd_parms->reachable_time = neigh_rand_reach_time(rtime);
  				in6_dev->tstamp = jiffies;
  				inet6_ifinfo_notify(RTM_NEWLINK, in6_dev);
  			}
  		}
  	}
  
  skip_linkparms:
  
  	/*
  	 *	Process options.
  	 */
  
  	if (!neigh)
  		neigh = __neigh_lookup(&nd_tbl, &ipv6_hdr(skb)->saddr,
  				       skb->dev, 1);
  	if (neigh) {
  		u8 *lladdr = NULL;
  		if (ndopts.nd_opts_src_lladdr) {
  			lladdr = ndisc_opt_addr_data(ndopts.nd_opts_src_lladdr,
  						     skb->dev);
  			if (!lladdr) {
  				ND_PRINTK(2, warn,
  					  "RA: invalid link-layer address length\n");
  				goto out;
  			}
  		}
  		neigh_update(neigh, lladdr, NUD_STALE,
  			     NEIGH_UPDATE_F_WEAK_OVERRIDE|
  			     NEIGH_UPDATE_F_OVERRIDE|
  			     NEIGH_UPDATE_F_OVERRIDE_ISROUTER|
  			     NEIGH_UPDATE_F_ISROUTER);
  	}
  
  	if (!ipv6_accept_ra(in6_dev))
  		goto out;
  
  #ifdef CONFIG_IPV6_ROUTE_INFO
  	if (ipv6_chk_addr(dev_net(in6_dev->dev), &ipv6_hdr(skb)->saddr, NULL, 0))
  		goto skip_routeinfo;
  
  	if (in6_dev->cnf.accept_ra_rtr_pref && ndopts.nd_opts_ri) {
  		struct nd_opt_hdr *p;
  		for (p = ndopts.nd_opts_ri;
  		     p;
  		     p = ndisc_next_option(p, ndopts.nd_opts_ri_end)) {
  			struct route_info *ri = (struct route_info *)p;
  #ifdef CONFIG_IPV6_NDISC_NODETYPE
  			if (skb->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT &&
  			    ri->prefix_len == 0)
  				continue;
  #endif
  			if (ri->prefix_len > in6_dev->cnf.accept_ra_rt_info_max_plen)
  				continue;
  			rt6_route_rcv(skb->dev, (u8*)p, (p->nd_opt_len) << 3,
  				      &ipv6_hdr(skb)->saddr);
  		}
  	}
  
  skip_routeinfo:
  #endif
  
  #ifdef CONFIG_IPV6_NDISC_NODETYPE
  	/* skip link-specific ndopts from interior routers */
  	if (skb->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT)
  		goto out;
  #endif
  
  	if (in6_dev->cnf.accept_ra_pinfo && ndopts.nd_opts_pi) {
  		struct nd_opt_hdr *p;
  		for (p = ndopts.nd_opts_pi;
  		     p;
  		     p = ndisc_next_option(p, ndopts.nd_opts_pi_end)) {
  			addrconf_prefix_rcv(skb->dev, (u8 *)p,
  					    (p->nd_opt_len) << 3,
  					    ndopts.nd_opts_src_lladdr != NULL);
  		}
  	}
  
  	if (ndopts.nd_opts_mtu) {
  		__be32 n;
  		u32 mtu;
  
  		memcpy(&n, ((u8*)(ndopts.nd_opts_mtu+1))+2, sizeof(mtu));
  		mtu = ntohl(n);
  
  		if (mtu < IPV6_MIN_MTU || mtu > skb->dev->mtu) {
  			ND_PRINTK(2, warn, "RA: invalid mtu: %d\n", mtu);
  		} else if (in6_dev->cnf.mtu6 != mtu) {
  			in6_dev->cnf.mtu6 = mtu;
  
  			if (rt)
  				dst_metric_set(&rt->dst, RTAX_MTU, mtu);
  
  			rt6_mtu_change(skb->dev, mtu);
  		}
  	}
  
  	if (ndopts.nd_useropts) {
  		struct nd_opt_hdr *p;
  		for (p = ndopts.nd_useropts;
  		     p;
  		     p = ndisc_next_useropt(p, ndopts.nd_useropts_end)) {
  			ndisc_ra_useropt(skb, p);
  		}
  	}
  
  	if (ndopts.nd_opts_tgt_lladdr || ndopts.nd_opts_rh) {
  		ND_PRINTK(2, warn, "RA: invalid RA options\n");
  	}
  out:
  	ip6_rt_put(rt);
  	if (neigh)
  		neigh_release(neigh);
  }
  
  static void ndisc_redirect_rcv(struct sk_buff *skb)
  {
  	u8 *hdr;
  	struct ndisc_options ndopts;
  	struct rd_msg *msg = (struct rd_msg *)skb_transport_header(skb);
  	u32 ndoptlen = skb->tail - (skb->transport_header +
  				    offsetof(struct rd_msg, opt));
  
  #ifdef CONFIG_IPV6_NDISC_NODETYPE
  	switch (skb->ndisc_nodetype) {
  	case NDISC_NODETYPE_HOST:
  	case NDISC_NODETYPE_NODEFAULT:
  		ND_PRINTK(2, warn,
  			  "Redirect: from host or unauthorized router\n");
  		return;
  	}
  #endif
  
  	if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL)) {
  		ND_PRINTK(2, warn,
  			  "Redirect: source address is not link-local\n");
  		return;
  	}
  
  	if (!ndisc_parse_options(msg->opt, ndoptlen, &ndopts))
  		return;
  
  	if (!ndopts.nd_opts_rh)
  		return;
  
  	hdr = (u8 *)ndopts.nd_opts_rh;
  	hdr += 8;
  	if (!pskb_pull(skb, hdr - skb_transport_header(skb)))
  		return;
  
  	icmpv6_notify(skb, NDISC_REDIRECT, 0, 0);
  }
  
  static void ndisc_fill_redirect_hdr_option(struct sk_buff *skb,
  					   struct sk_buff *orig_skb,
  					   int rd_len)
  {
  	u8 *opt = skb_put(skb, rd_len);
  
  	memset(opt, 0, 8);
  	*(opt++) = ND_OPT_REDIRECT_HDR;
  	*(opt++) = (rd_len >> 3);
  	opt += 6;
  
  	memcpy(opt, ipv6_hdr(orig_skb), rd_len - 8);
  }
  
  void ndisc_send_redirect(struct sk_buff *skb, const struct in6_addr *target)
  {
  	struct net_device *dev = skb->dev;
  	struct net *net = dev_net(dev);
  	struct sock *sk = net->ipv6.ndisc_sk;
  	int optlen = 0;
  	struct inet_peer *peer;
  	struct sk_buff *buff;
  	struct rd_msg *msg;
  	struct in6_addr saddr_buf;
  	struct rt6_info *rt;
  	struct dst_entry *dst;
  	struct flowi6 fl6;
  	int rd_len;
  	u8 ha_buf[MAX_ADDR_LEN], *ha = NULL;
  	bool ret;
  
  	if (ipv6_get_lladdr(dev, &saddr_buf, IFA_F_TENTATIVE)) {
  		ND_PRINTK(2, warn, "Redirect: no link-local address on %s\n",
  			  dev->name);
  		return;
  	}
  
  	if (!ipv6_addr_equal(&ipv6_hdr(skb)->daddr, target) &&
  	    ipv6_addr_type(target) != (IPV6_ADDR_UNICAST|IPV6_ADDR_LINKLOCAL)) {
  		ND_PRINTK(2, warn,
  			  "Redirect: target address is not link-local unicast\n");
  		return;
  	}
  
  	icmpv6_flow_init(sk, &fl6, NDISC_REDIRECT,
  			 &saddr_buf, &ipv6_hdr(skb)->saddr, dev->ifindex);
  
  	dst = ip6_route_output(net, NULL, &fl6);
  	if (dst->error) {
  		dst_release(dst);
  		return;
  	}
  	dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
  	if (IS_ERR(dst))
  		return;
  
  	rt = (struct rt6_info *) dst;
  
  	if (rt->rt6i_flags & RTF_GATEWAY) {
  		ND_PRINTK(2, warn,
  			  "Redirect: destination is not a neighbour\n");
  		goto release;
  	}
  	peer = inet_getpeer_v6(net->ipv6.peers, &rt->rt6i_dst.addr, 1);
  	ret = inet_peer_xrlim_allow(peer, 1*HZ);
  	if (peer)
  		inet_putpeer(peer);
  	if (!ret)
  		goto release;
  
  	if (dev->addr_len) {
  		struct neighbour *neigh = dst_neigh_lookup(skb_dst(skb), target);
  		if (!neigh) {
  			ND_PRINTK(2, warn,
  				  "Redirect: no neigh for target address\n");
  			goto release;
  		}
  
  		read_lock_bh(&neigh->lock);
  		if (neigh->nud_state & NUD_VALID) {
  			memcpy(ha_buf, neigh->ha, dev->addr_len);
  			read_unlock_bh(&neigh->lock);
  			ha = ha_buf;
  			optlen += ndisc_opt_addr_space(dev);
  		} else
  			read_unlock_bh(&neigh->lock);
  
  		neigh_release(neigh);
  	}
  
  	rd_len = min_t(unsigned int,
  		       IPV6_MIN_MTU - sizeof(struct ipv6hdr) - sizeof(*msg) - optlen,
  		       skb->len + 8);
  	rd_len &= ~0x7;
  	optlen += rd_len;
  
  	buff = ndisc_alloc_skb(dev, sizeof(*msg) + optlen);
  	if (!buff)
  		goto release;
  
  	msg = (struct rd_msg *)skb_put(buff, sizeof(*msg));
  	*msg = (struct rd_msg) {
  		.icmph = {
  			.icmp6_type = NDISC_REDIRECT,
  		},
  		.target = *target,
  		.dest = ipv6_hdr(skb)->daddr,
  	};
  
  	/*
  	 *	include target_address option
  	 */
  
  	if (ha)
  		ndisc_fill_addr_option(buff, ND_OPT_TARGET_LL_ADDR, ha);
  
  	/*
  	 *	build redirect option and copy skb over to the new packet.
  	 */
  
  	if (rd_len)
  		ndisc_fill_redirect_hdr_option(buff, skb, rd_len);
  
  	skb_dst_set(buff, dst);
  	ndisc_send_skb(buff, &ipv6_hdr(skb)->saddr, &saddr_buf);
  	return;
  
  release:
  	dst_release(dst);
  }
  
  static void pndisc_redo(struct sk_buff *skb)
  {
  	ndisc_recv_ns(skb);
  	kfree_skb(skb);
  }
  
  int ndisc_rcv(struct sk_buff *skb)
  {
  	struct nd_msg *msg;
  
  	if (skb_linearize(skb))
  		return 0;
  
  	msg = (struct nd_msg *)skb_transport_header(skb);
  
  	__skb_push(skb, skb->data - skb_transport_header(skb));
  
  	if (ipv6_hdr(skb)->hop_limit != 255) {
  		ND_PRINTK(2, warn, "NDISC: invalid hop-limit: %d\n",
  			  ipv6_hdr(skb)->hop_limit);
  		return 0;
  	}
  
  	if (msg->icmph.icmp6_code != 0) {
  		ND_PRINTK(2, warn, "NDISC: invalid ICMPv6 code: %d\n",
  			  msg->icmph.icmp6_code);
  		return 0;
  	}
  
  	memset(NEIGH_CB(skb), 0, sizeof(struct neighbour_cb));
  
  	switch (msg->icmph.icmp6_type) {
  	case NDISC_NEIGHBOUR_SOLICITATION:
  		ndisc_recv_ns(skb);
  		break;
  
  	case NDISC_NEIGHBOUR_ADVERTISEMENT:
  		ndisc_recv_na(skb);
  		break;
  
  	case NDISC_ROUTER_SOLICITATION:
  		ndisc_recv_rs(skb);
  		break;
  
  	case NDISC_ROUTER_ADVERTISEMENT:
  		ndisc_router_discovery(skb);
  		break;
  
  	case NDISC_REDIRECT:
  		ndisc_redirect_rcv(skb);
  		break;
  	}
  
  	return 0;
  }
  
  static int ndisc_netdev_event(struct notifier_block *this, unsigned long event, void *ptr)
  {
  	struct net_device *dev = ptr;
  	struct net *net = dev_net(dev);
  	struct inet6_dev *idev;
  
  	switch (event) {
  	case NETDEV_CHANGEADDR:
  		neigh_changeaddr(&nd_tbl, dev);
  		fib6_run_gc(~0UL, net);
  		idev = in6_dev_get(dev);
  		if (!idev)
  			break;
  		if (idev->cnf.ndisc_notify)
  			ndisc_send_unsol_na(dev);
  		in6_dev_put(idev);
  		break;
  	case NETDEV_DOWN:
  		neigh_ifdown(&nd_tbl, dev);
  		fib6_run_gc(~0UL, net);
  		break;
  	case NETDEV_NOTIFY_PEERS:
  		ndisc_send_unsol_na(dev);
  		break;
  	default:
  		break;
  	}
  
  	return NOTIFY_DONE;
  }
  
  static struct notifier_block ndisc_netdev_notifier = {
  	.notifier_call = ndisc_netdev_event,
  };
  
  #ifdef CONFIG_SYSCTL
  static void ndisc_warn_deprecated_sysctl(struct ctl_table *ctl,
  					 const char *func, const char *dev_name)
  {
  	static char warncomm[TASK_COMM_LEN];
  	static int warned;
  	if (strcmp(warncomm, current->comm) && warned < 5) {
  		strcpy(warncomm, current->comm);
  		pr_warn("process `%s' is using deprecated sysctl (%s) net.ipv6.neigh.%s.%s - use net.ipv6.neigh.%s.%s_ms instead\n",
  			warncomm, func,
  			dev_name, ctl->procname,
  			dev_name, ctl->procname);
  		warned++;
  	}
  }
  
  int ndisc_ifinfo_sysctl_change(struct ctl_table *ctl, int write, void __user *buffer, size_t *lenp, loff_t *ppos)
  {
  	struct net_device *dev = ctl->extra1;
  	struct inet6_dev *idev;
  	int ret;
  
  	if ((strcmp(ctl->procname, "retrans_time") == 0) ||
  	    (strcmp(ctl->procname, "base_reachable_time") == 0))
  		ndisc_warn_deprecated_sysctl(ctl, "syscall", dev ? dev->name : "default");
  
  	if (strcmp(ctl->procname, "retrans_time") == 0)
  		ret = proc_dointvec(ctl, write, buffer, lenp, ppos);
  
  	else if (strcmp(ctl->procname, "base_reachable_time") == 0)
  		ret = proc_dointvec_jiffies(ctl, write,
  					    buffer, lenp, ppos);
  
  	else if ((strcmp(ctl->procname, "retrans_time_ms") == 0) ||
  		 (strcmp(ctl->procname, "base_reachable_time_ms") == 0))
  		ret = proc_dointvec_ms_jiffies(ctl, write,
  					       buffer, lenp, ppos);
  	else
  		ret = -1;
  
  	if (write && ret == 0 && dev && (idev = in6_dev_get(dev)) != NULL) {
  		if (ctl->data == &idev->nd_parms->base_reachable_time)
  			idev->nd_parms->reachable_time = neigh_rand_reach_time(idev->nd_parms->base_reachable_time);
  		idev->tstamp = jiffies;
  		inet6_ifinfo_notify(RTM_NEWLINK, idev);
  		in6_dev_put(idev);
  	}
  	return ret;
  }
  
  
  #endif
  
  static int __net_init ndisc_net_init(struct net *net)
  {
  	struct ipv6_pinfo *np;
  	struct sock *sk;
  	int err;
  
  	err = inet_ctl_sock_create(&sk, PF_INET6,
  				   SOCK_RAW, IPPROTO_ICMPV6, net);
  	if (err < 0) {
  		ND_PRINTK(0, err,
  			  "NDISC: Failed to initialize the control socket (err %d)\n",
  			  err);
  		return err;
  	}
  
  	net->ipv6.ndisc_sk = sk;
  
  	np = inet6_sk(sk);
  	np->hop_limit = 255;
  	/* Do not loopback ndisc messages */
  	np->mc_loop = 0;
  
  	return 0;
  }
  
  static void __net_exit ndisc_net_exit(struct net *net)
  {
  	inet_ctl_sock_destroy(net->ipv6.ndisc_sk);
  }
  
  static struct pernet_operations ndisc_net_ops = {
  	.init = ndisc_net_init,
  	.exit = ndisc_net_exit,
  };
  
  int __init ndisc_init(void)
  {
  	int err;
  
  	err = register_pernet_subsys(&ndisc_net_ops);
  	if (err)
  		return err;
  	/*
  	 * Initialize the neighbour table
  	 */
  	neigh_table_init(&nd_tbl);
  
  #ifdef CONFIG_SYSCTL
  	err = neigh_sysctl_register(NULL, &nd_tbl.parms, "ipv6",
  				    &ndisc_ifinfo_sysctl_change);
  	if (err)
  		goto out_unregister_pernet;
  #endif
  	err = register_netdevice_notifier(&ndisc_netdev_notifier);
  	if (err)
  		goto out_unregister_sysctl;
  out:
  	return err;
  
  out_unregister_sysctl:
  #ifdef CONFIG_SYSCTL
  	neigh_sysctl_unregister(&nd_tbl.parms);
  out_unregister_pernet:
  #endif
  	unregister_pernet_subsys(&ndisc_net_ops);
  	goto out;
  }
  
  void ndisc_cleanup(void)
  {
  	unregister_netdevice_notifier(&ndisc_netdev_notifier);
  #ifdef CONFIG_SYSCTL
  	neigh_sysctl_unregister(&nd_tbl.parms);
  #endif
  	neigh_table_clear(&nd_tbl);
  	unregister_pernet_subsys(&ndisc_net_ops);
  }
  