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ndisc.c

/*
 *    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:
 *
 *    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
 */

/* Set to 3 to get tracing... */
#define ND_DEBUG 1

#define ND_PRINTK(fmt, args...) do { if (net_ratelimit()) { printk(fmt, ## args); } } while(0)
#define ND_NOPRINTK(x...) do { ; } while(0)
#define ND_PRINTK0 ND_PRINTK
#define ND_PRINTK1 ND_NOPRINTK
#define ND_PRINTK2 ND_NOPRINTK
#define ND_PRINTK3 ND_NOPRINTK
#if ND_DEBUG >= 1
#undef ND_PRINTK1
#define ND_PRINTK1 ND_PRINTK
#endif
#if ND_DEBUG >= 2
#undef ND_PRINTK2
#define ND_PRINTK2 ND_PRINTK
#endif
#if ND_DEBUG >= 3
#undef ND_PRINTK3
#define ND_PRINTK3 ND_PRINTK
#endif

#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>
#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 <linux/proc_fs.h>

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

static struct socket *ndisc_socket;

static u32 ndisc_hash(const void *pkey, const struct net_device *dev);
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 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,
      .hh_output =            dev_queue_xmit,
      .queue_xmit =           dev_queue_xmit,
};

static 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,
      .hh_output =            dev_queue_xmit,
      .queue_xmit =           dev_queue_xmit,
};


static struct neigh_ops ndisc_direct_ops = {
      .family =         AF_INET6,
      .output =         dev_queue_xmit,
      .connected_output =     dev_queue_xmit,
      .hh_output =            dev_queue_xmit,
      .queue_xmit =           dev_queue_xmit,
};

struct neigh_table nd_tbl = {
      .family =   AF_INET6,
      .entry_size =     sizeof(struct neighbour) + sizeof(struct in6_addr),
      .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 =  30 * HZ,
            .retrans_time =    1 * HZ,
            .gc_staletime =   60 * HZ,
            .reachable_time =       30 * HZ,
            .delay_probe_time =      5 * HZ,
            .queue_len =             3,
            .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,
};

/* ND options */
struct ndisc_options {
      struct nd_opt_hdr *nd_opt_array[__ND_OPT_ARRAY_MAX];
#ifdef CONFIG_IPV6_ROUTE_INFO
      struct nd_opt_hdr *nd_opts_ri;
      struct nd_opt_hdr *nd_opts_ri_end;
#endif
      struct nd_opt_hdr *nd_useropts;
      struct nd_opt_hdr *nd_useropts_end;
};

#define nd_opts_src_lladdr    nd_opt_array[ND_OPT_SOURCE_LL_ADDR]
#define nd_opts_tgt_lladdr    nd_opt_array[ND_OPT_TARGET_LL_ADDR]
#define nd_opts_pi            nd_opt_array[ND_OPT_PREFIX_INFO]
#define nd_opts_pi_end        nd_opt_array[__ND_OPT_PREFIX_INFO_END]
#define nd_opts_rh            nd_opt_array[ND_OPT_REDIRECT_HDR]
#define nd_opts_mtu           nd_opt_array[ND_OPT_MTU]

#define NDISC_OPT_SPACE(len) (((len)+2+7)&~7)

/*
 * Return the padding between the option length and the start of the
 * link addr.  Currently only IP-over-InfiniBand needs this, although
 * if RFC 3831 IPv6-over-Fibre Channel is ever implemented it may
 * also need a pad of 2.
 */
static int ndisc_addr_option_pad(unsigned short type)
{
      switch (type) {
      case ARPHRD_INFINIBAND: return 2;
      default:                return 0;
      }
}

static inline int ndisc_opt_addr_space(struct net_device *dev)
{
      return NDISC_OPT_SPACE(dev->addr_len + ndisc_addr_option_pad(dev->type));
}

static u8 *ndisc_fill_addr_option(u8 *opt, int type, void *data, int data_len,
                          unsigned short addr_type)
{
      int space = NDISC_OPT_SPACE(data_len);
      int pad   = ndisc_addr_option_pad(addr_type);

      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);
      return opt + 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);
}

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);
}

static 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_PRINTK2(KERN_WARNING
                                 "%s(): duplicated ND6 option found: type=%d\n",
                                 __FUNCTION__,
                                 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_PRINTK2(KERN_NOTICE
                                 "%s(): ignored unsupported option; type=%d, len=%d\n",
                                 __FUNCTION__,
                                 nd_opt->nd_opt_type, nd_opt->nd_opt_len);
                  }
            }
            opt_len -= l;
            nd_opt = ((void *)nd_opt) + l;
      }
      return ndopts;
}

static inline u8 *ndisc_opt_addr_data(struct nd_opt_hdr *p,
                              struct net_device *dev)
{
      u8 *lladdr = (u8 *)(p + 1);
      int lladdrlen = p->nd_opt_len << 3;
      int prepad = ndisc_addr_option_pad(dev->type);
      if (lladdrlen != NDISC_OPT_SPACE(dev->addr_len + prepad))
            return NULL;
      return (lladdr + prepad);
}

int ndisc_mc_map(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_IEEE802_TR:
            ipv6_tr_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, buf);
            return 0;
      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)
{
      const u32 *p32 = pkey;
      u32 addr_hash, i;

      addr_hash = 0;
      for (i = 0; i < (sizeof(struct in6_addr) / sizeof(u32)); i++)
            addr_hash ^= *p32++;

      return jhash_2words(addr_hash, dev->ifindex, nd_tbl.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;
      int is_multicast = ipv6_addr_is_multicast(addr);

      rcu_read_lock();
      in6_dev = in6_dev_get(dev);
      if (in6_dev == NULL) {
            rcu_read_unlock();
            return -EINVAL;
      }

      parms = in6_dev->nd_parms;
      __neigh_parms_put(neigh->parms);
      neigh->parms = neigh_parms_clone(parms);
      rcu_read_unlock();

      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->ops->queue_xmit;
      } 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);
}

/*
 *    Send a Neighbour Advertisement
 */

static inline void ndisc_flow_init(struct flowi *fl, u8 type,
                      struct in6_addr *saddr, 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(ndisc_socket->sk, fl);
}

static void __ndisc_send(struct net_device *dev,
                   struct neighbour *neigh,
                   struct in6_addr *daddr, struct in6_addr *saddr,
                   struct icmp6hdr *icmp6h, struct in6_addr *target,
                   int llinfo)
{
      struct flowi fl;
      struct dst_entry *dst;
      struct sock *sk = ndisc_socket->sk;
      struct sk_buff *skb;
      struct icmp6hdr *hdr;
      struct inet6_dev *idev;
      int len;
      int err;
      u8 *opt, type;

      type = icmp6h->icmp6_type;

      ndisc_flow_init(&fl, type, saddr, daddr,
                  dev->ifindex);

      dst = ndisc_dst_alloc(dev, neigh, daddr, ip6_output);
      if (!dst)
            return;

      err = xfrm_lookup(&dst, &fl, NULL, 0);
      if (err < 0)
            return;

      if (!dev->addr_len)
            llinfo = 0;

      len = sizeof(struct icmp6hdr) + (target ? sizeof(*target) : 0);
      if (llinfo)
            len += ndisc_opt_addr_space(dev);

      skb = sock_alloc_send_skb(sk,
                          (MAX_HEADER + sizeof(struct ipv6hdr) +
                           len + LL_RESERVED_SPACE(dev)),
                          1, &err);
      if (!skb) {
            ND_PRINTK0(KERN_ERR
                     "ICMPv6 ND: %s() failed to allocate an skb.\n",
                     __FUNCTION__);
            dst_release(dst);
            return;
      }

      skb_reserve(skb, LL_RESERVED_SPACE(dev));
      ip6_nd_hdr(sk, skb, dev, saddr, daddr, IPPROTO_ICMPV6, len);

      skb->transport_header = skb->tail;
      skb_put(skb, len);

      hdr = (struct icmp6hdr *)skb_transport_header(skb);
      memcpy(hdr, icmp6h, sizeof(*hdr));

      opt = skb_transport_header(skb) + sizeof(struct icmp6hdr);
      if (target) {
            ipv6_addr_copy((struct in6_addr *)opt, target);
            opt += sizeof(*target);
      }

      if (llinfo)
            ndisc_fill_addr_option(opt, llinfo, dev->dev_addr,
                               dev->addr_len, dev->type);

      hdr->icmp6_cksum = csum_ipv6_magic(saddr, daddr, len,
                                 IPPROTO_ICMPV6,
                                 csum_partial((__u8 *) hdr,
                                          len, 0));

      skb->dst = dst;

      idev = in6_dev_get(dst->dev);
      IP6_INC_STATS(idev, IPSTATS_MIB_OUTREQUESTS);

      err = NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, skb, NULL, dst->dev, dst_output);
      if (!err) {
            ICMP6MSGOUT_INC_STATS(idev, type);
            ICMP6_INC_STATS(idev, ICMP6_MIB_OUTMSGS);
      }

      if (likely(idev != NULL))
            in6_dev_put(idev);
}

static void ndisc_send_na(struct net_device *dev, struct neighbour *neigh,
               struct in6_addr *daddr, struct in6_addr *solicited_addr,
               int router, int solicited, int override, int inc_opt)
{
      struct in6_addr tmpaddr;
      struct inet6_ifaddr *ifp;
      struct in6_addr *src_addr;
      struct icmp6hdr icmp6h = {
            .icmp6_type = NDISC_NEIGHBOUR_ADVERTISEMENT,
      };

      /* for anycast or proxy, solicited_addr != src_addr */
      ifp = ipv6_get_ifaddr(solicited_addr, dev, 1);
      if (ifp) {
            src_addr = solicited_addr;
            if (ifp->flags & IFA_F_OPTIMISTIC)
                  override = 0;
            in6_ifa_put(ifp);
      } else {
            if (ipv6_dev_get_saddr(dev, daddr, &tmpaddr))
                  return;
            src_addr = &tmpaddr;
      }

      icmp6h.icmp6_router = router;
      icmp6h.icmp6_solicited = solicited;
      icmp6h.icmp6_override = override;

      __ndisc_send(dev, neigh, daddr, src_addr,
                 &icmp6h, solicited_addr,
                 inc_opt ? ND_OPT_TARGET_LL_ADDR : 0);
}

void ndisc_send_ns(struct net_device *dev, struct neighbour *neigh,
               struct in6_addr *solicit,
               struct in6_addr *daddr, struct in6_addr *saddr)
{
      struct in6_addr addr_buf;
      struct icmp6hdr icmp6h = {
            .icmp6_type = NDISC_NEIGHBOUR_SOLICITATION,
      };

      if (saddr == NULL) {
            if (ipv6_get_lladdr(dev, &addr_buf,
                           (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)))
                  return;
            saddr = &addr_buf;
      }

      __ndisc_send(dev, neigh, daddr, saddr,
                 &icmp6h, solicit,
                 !ipv6_addr_any(saddr) ? ND_OPT_SOURCE_LL_ADDR : 0);
}

void ndisc_send_rs(struct net_device *dev, struct in6_addr *saddr,
               struct in6_addr *daddr)
{
      struct icmp6hdr icmp6h = {
            .icmp6_type = NDISC_ROUTER_SOLICITATION,
      };
      int send_sllao = dev->addr_len;

#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(saddr, dev, 1);
            if (ifp) {
                  if (ifp->flags & IFA_F_OPTIMISTIC)  {
                        send_sllao = 0;
                  }
                  in6_ifa_put(ifp);
            } else {
                  send_sllao = 0;
            }
      }
#endif
      __ndisc_send(dev, NULL, daddr, saddr,
                 &icmp6h, NULL,
                 send_sllao ? ND_OPT_SOURCE_LL_ADDR : 0);
}


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(&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_PRINTK1(KERN_DEBUG
                           "%s(): trying to ucast probe in NUD_INVALID: "
                           NIP6_FMT "\n",
                           __FUNCTION__,
                           NIP6(*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 void ndisc_recv_ns(struct sk_buff *skb)
{
      struct nd_msg *msg = (struct nd_msg *)skb_transport_header(skb);
      struct in6_addr *saddr = &ipv6_hdr(skb)->saddr;
      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;
      struct pneigh_entry *pneigh = NULL;
      int dad = ipv6_addr_any(saddr);
      int inc;
      int is_router;

      if (ipv6_addr_is_multicast(&msg->target)) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 NS: multicast target address");
            return;
      }

      /*
       * RFC2461 7.1.1:
       * DAD has to be destined for solicited node multicast address.
       */
      if (dad &&
          !(daddr->s6_addr32[0] == htonl(0xff020000) &&
            daddr->s6_addr32[1] == htonl(0x00000000) &&
            daddr->s6_addr32[2] == htonl(0x00000001) &&
            daddr->s6_addr [12] == 0xff )) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 NS: bad DAD packet (wrong destination)\n");
            return;
      }

      if (!ndisc_parse_options(msg->opt, ndoptlen, &ndopts)) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 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_PRINTK2(KERN_WARNING
                           "ICMPv6 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_PRINTK2(KERN_WARNING
                           "ICMPv6 NS: bad DAD packet (link-layer address option)\n");
                  return;
            }
      }

      inc = ipv6_addr_is_multicast(daddr);

      if ((ifp = ipv6_get_ifaddr(&msg->target, dev, 1)) != NULL) {

            if (ifp->flags & (IFA_F_TENTATIVE|IFA_F_OPTIMISTIC)) {
                  if (dad) {
                        if (dev->type == ARPHRD_IEEE802_TR) {
                              const unsigned char *sadr;
                              sadr = skb_mac_header(skb);
                              if (((sadr[8] ^ dev->dev_addr[0]) & 0x7f) == 0 &&
                                  sadr[9] == dev->dev_addr[1] &&
                                  sadr[10] == dev->dev_addr[2] &&
                                  sadr[11] == dev->dev_addr[3] &&
                                  sadr[12] == dev->dev_addr[4] &&
                                  sadr[13] == dev->dev_addr[5]) {
                                    /* looped-back to us */
                                    goto out;
                              }
                        }

                        /*
                         * 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 {
            idev = in6_dev_get(dev);
            if (!idev) {
                  /* XXX: count this drop? */
                  return;
            }

            if (ipv6_chk_acast_addr(dev, &msg->target) ||
                (idev->cnf.forwarding &&
                 (ipv6_devconf.proxy_ndp || idev->cnf.proxy_ndp) &&
                 (pneigh = pneigh_lookup(&nd_tbl,
                                   &msg->target, dev, 0)) != NULL)) {
                  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;
      }

      is_router = !!(pneigh ? pneigh->flags & NTF_ROUTER : idev->cnf.forwarding);

      if (dad) {
            struct in6_addr maddr;

            ipv6_addr_all_nodes(&maddr);
            ndisc_send_na(dev, NULL, &maddr, &msg->target,
                        is_router, 0, (ifp != NULL), 1);
            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,
                        1, (ifp != NULL && inc), inc);
            if (neigh)
                  neigh_release(neigh);
      }

out:
      if (ifp)
            in6_ifa_put(ifp);
      else
            in6_dev_put(idev);

      return;
}

static void ndisc_recv_na(struct sk_buff *skb)
{
      struct nd_msg *msg = (struct nd_msg *)skb_transport_header(skb);
      struct in6_addr *saddr = &ipv6_hdr(skb)->saddr;
      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_PRINTK2(KERN_WARNING
                     "ICMPv6 NA: packet too short\n");
            return;
      }

      if (ipv6_addr_is_multicast(&msg->target)) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 NA: target address is multicast.\n");
            return;
      }

      if (ipv6_addr_is_multicast(daddr) &&
          msg->icmph.icmp6_solicited) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 NA: solicited NA is multicasted.\n");
            return;
      }

      if (!ndisc_parse_options(msg->opt, ndoptlen, &ndopts)) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 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_PRINTK2(KERN_WARNING
                           "ICMPv6 NA: invalid link-layer address length\n");
                  return;
            }
      }
      if ((ifp = ipv6_get_ifaddr(&msg->target, dev, 1))) {
            if (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 :-)
             */
            ND_PRINTK1(KERN_WARNING
                     "ICMPv6 NA: someone advertises our address on %s!\n",
                     ifp->idev->dev->name);
            in6_ifa_put(ifp);
            return;
      }
      neigh = neigh_lookup(&nd_tbl, &msg->target, dev);

      if (neigh) {
            u8 old_flags = neigh->flags;

            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) &&
                ipv6_devconf.forwarding && ipv6_devconf.proxy_ndp &&
                pneigh_lookup(&nd_tbl, &msg->target, dev, 0)) {
                  /* XXX: idev->cnf.prixy_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;
      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) {
            if (net_ratelimit())
                  ND_PRINTK1("ICMP6 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)) {
            if (net_ratelimit())
                  ND_PRINTK2("ICMP6 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:
      in6_dev_put(idev);
}

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;
      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);

      NLA_PUT(skb, NDUSEROPT_SRCADDR, sizeof(struct in6_addr),
            &ipv6_hdr(ra)->saddr);
      nlmsg_end(skb, nlh);

      err = rtnl_notify(skb, 0, RTNLGRP_ND_USEROPT, NULL, GFP_ATOMIC);
      if (err < 0)
            goto errout;

      return;

nla_put_failure:
      nlmsg_free(skb);
      err = -EMSGSIZE;
errout:
      rtnl_set_sk_err(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_PRINTK2(KERN_WARNING
                     "ICMPv6 RA: source address is not link-local.\n");
            return;
      }
      if (optlen < 0) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 RA: packet too short\n");
            return;
      }

      /*
       *    set the RA_RECV flag in the interface
       */

      in6_dev = in6_dev_get(skb->dev);
      if (in6_dev == NULL) {
            ND_PRINTK0(KERN_ERR
                     "ICMPv6 RA: can't find inet6 device for %s.\n",
                     skb->dev->name);
            return;
      }
      if (in6_dev->cnf.forwarding || !in6_dev->cnf.accept_ra) {
            in6_dev_put(in6_dev);
            return;
      }

      if (!ndisc_parse_options(opt, optlen, &ndopts)) {
            in6_dev_put(in6_dev);
            ND_PRINTK2(KERN_WARNING
                     "ICMP6 RA: invalid ND options\n");
            return;
      }

      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;

      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 = rt->rt6i_nexthop;

      if (rt && lifetime == 0) {
            neigh_clone(neigh);
            ip6_del_rt(rt);
            rt = NULL;
      }

      if (rt == NULL && lifetime) {
            ND_PRINTK3(KERN_DEBUG
                     "ICMPv6 RA: adding default router.\n");

            rt = rt6_add_dflt_router(&ipv6_hdr(skb)->saddr, skb->dev, pref);
            if (rt == NULL) {
                  ND_PRINTK0(KERN_ERR
                           "ICMPv6 RA: %s() failed to add default route.\n",
                           __FUNCTION__);
                  in6_dev_put(in6_dev);
                  return;
            }

            neigh = rt->rt6i_nexthop;
            if (neigh == NULL) {
                  ND_PRINTK0(KERN_ERR
                           "ICMPv6 RA: %s() got default router without neighbour.\n",
                           __FUNCTION__);
                  dst_release(&rt->u.dst);
                  in6_dev_put(in6_dev);
                  return;
            }
            neigh->flags |= NTF_ROUTER;
      } else if (rt) {
            rt->rt6i_flags |= (rt->rt6i_flags & ~RTF_PREF_MASK) | RTF_PREF(pref);
      }

      if (rt)
            rt->rt6i_expires = jiffies + (HZ * lifetime);

      if (ra_msg->icmph.icmp6_hop_limit) {
            in6_dev->cnf.hop_limit = ra_msg->icmph.icmp6_hop_limit;
            if (rt)
                  rt->u.dst.metrics[RTAX_HOPLIMIT-1] = 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);
                  }
            }
      }

      /*
       *    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_PRINTK2(KERN_WARNING
                                 "ICMPv6 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);
      }

#ifdef CONFIG_IPV6_ROUTE_INFO
      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)) {
                  if (((struct route_info *)p)->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);
            }
      }
#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);
            }
      }

      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_PRINTK2(KERN_WARNING
                           "ICMPv6 RA: invalid mtu: %d\n",
                           mtu);
            } else if (in6_dev->cnf.mtu6 != mtu) {
                  in6_dev->cnf.mtu6 = mtu;

                  if (rt)
                        rt->u.dst.metrics[RTAX_MTU-1] = mtu;

                  rt6_mtu_change(skb->dev, mtu);
            }
      }

      if (ndopts.nd_useropts) {
            struct nd_opt_hdr *opt;
            for (opt = ndopts.nd_useropts;
                 opt;
                 opt = ndisc_next_useropt(opt, ndopts.nd_useropts_end)) {
                        ndisc_ra_useropt(skb, opt);
            }
      }

      if (ndopts.nd_opts_tgt_lladdr || ndopts.nd_opts_rh) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 RA: invalid RA options");
      }
out:
      if (rt)
            dst_release(&rt->u.dst);
      else if (neigh)
            neigh_release(neigh);
      in6_dev_put(in6_dev);
}

static void ndisc_redirect_rcv(struct sk_buff *skb)
{
      struct inet6_dev *in6_dev;
      struct icmp6hdr *icmph;
      struct in6_addr *dest;
      struct in6_addr *target;      /* new first hop to destination */
      struct neighbour *neigh;
      int on_link = 0;
      struct ndisc_options ndopts;
      int optlen;
      u8 *lladdr = NULL;

      if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL)) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 Redirect: source address is not link-local.\n");
            return;
      }

      optlen = skb->tail - skb->transport_header;
      optlen -= sizeof(struct icmp6hdr) + 2 * sizeof(struct in6_addr);

      if (optlen < 0) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 Redirect: packet too short\n");
            return;
      }

      icmph = icmp6_hdr(skb);
      target = (struct in6_addr *) (icmph + 1);
      dest = target + 1;

      if (ipv6_addr_is_multicast(dest)) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 Redirect: destination address is multicast.\n");
            return;
      }

      if (ipv6_addr_equal(dest, target)) {
            on_link = 1;
      } else if (ipv6_addr_type(target) !=
               (IPV6_ADDR_UNICAST|IPV6_ADDR_LINKLOCAL)) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 Redirect: target address is not link-local unicast.\n");
            return;
      }

      in6_dev = in6_dev_get(skb->dev);
      if (!in6_dev)
            return;
      if (in6_dev->cnf.forwarding || !in6_dev->cnf.accept_redirects) {
            in6_dev_put(in6_dev);
            return;
      }

      /* RFC2461 8.1:
       *    The IP source address of the Redirect MUST be the same as the current
       *    first-hop router for the specified ICMP Destination Address.
       */

      if (!ndisc_parse_options((u8*)(dest + 1), optlen, &ndopts)) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 Redirect: invalid ND options\n");
            in6_dev_put(in6_dev);
            return;
      }
      if (ndopts.nd_opts_tgt_lladdr) {
            lladdr = ndisc_opt_addr_data(ndopts.nd_opts_tgt_lladdr,
                                   skb->dev);
            if (!lladdr) {
                  ND_PRINTK2(KERN_WARNING
                           "ICMPv6 Redirect: invalid link-layer address length\n");
                  in6_dev_put(in6_dev);
                  return;
            }
      }

      neigh = __neigh_lookup(&nd_tbl, target, skb->dev, 1);
      if (neigh) {
            rt6_redirect(dest, &ipv6_hdr(skb)->daddr,
                       &ipv6_hdr(skb)->saddr, neigh, lladdr,
                       on_link);
            neigh_release(neigh);
      }
      in6_dev_put(in6_dev);
}

void ndisc_send_redirect(struct sk_buff *skb, struct neighbour *neigh,
                   struct in6_addr *target)
{
      struct sock *sk = ndisc_socket->sk;
      int len = sizeof(struct icmp6hdr) + 2 * sizeof(struct in6_addr);
      struct sk_buff *buff;
      struct icmp6hdr *icmph;
      struct in6_addr saddr_buf;
      struct in6_addr *addrp;
      struct net_device *dev;
      struct rt6_info *rt;
      struct dst_entry *dst;
      struct inet6_dev *idev;
      struct flowi fl;
      u8 *opt;
      int rd_len;
      int err;
      int hlen;
      u8 ha_buf[MAX_ADDR_LEN], *ha = NULL;

      dev = skb->dev;

      if (ipv6_get_lladdr(dev, &saddr_buf, IFA_F_TENTATIVE)) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 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_PRINTK2(KERN_WARNING
                  "ICMPv6 Redirect: target address is not link-local unicast.\n");
            return;
      }

      ndisc_flow_init(&fl, NDISC_REDIRECT, &saddr_buf, &ipv6_hdr(skb)->saddr,
                  dev->ifindex);

      dst = ip6_route_output(NULL, &fl);
      if (dst == NULL)
            return;

      err = xfrm_lookup(&dst, &fl, NULL, 0);
      if (err)
            return;

      rt = (struct rt6_info *) dst;

      if (rt->rt6i_flags & RTF_GATEWAY) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 Redirect: destination is not a neighbour.\n");
            dst_release(dst);
            return;
      }
      if (!xrlim_allow(dst, 1*HZ)) {
            dst_release(dst);
            return;
      }

      if (dev->addr_len) {
            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;
                  len += ndisc_opt_addr_space(dev);
            } else
                  read_unlock_bh(&neigh->lock);
      }

      rd_len = min_t(unsigned int,
                 IPV6_MIN_MTU-sizeof(struct ipv6hdr)-len, skb->len + 8);
      rd_len &= ~0x7;
      len += rd_len;

      buff = sock_alloc_send_skb(sk,
                           (MAX_HEADER + sizeof(struct ipv6hdr) +
                            len + LL_RESERVED_SPACE(dev)),
                           1, &err);
      if (buff == NULL) {
            ND_PRINTK0(KERN_ERR
                     "ICMPv6 Redirect: %s() failed to allocate an skb.\n",
                     __FUNCTION__);
            dst_release(dst);
            return;
      }

      hlen = 0;

      skb_reserve(buff, LL_RESERVED_SPACE(dev));
      ip6_nd_hdr(sk, buff, dev, &saddr_buf, &ipv6_hdr(skb)->saddr,
               IPPROTO_ICMPV6, len);

      skb_set_transport_header(buff, skb_tail_pointer(buff) - buff->data);
      skb_put(buff, len);
      icmph = icmp6_hdr(buff);

      memset(icmph, 0, sizeof(struct icmp6hdr));
      icmph->icmp6_type = NDISC_REDIRECT;

      /*
       *    copy target and destination addresses
       */

      addrp = (struct in6_addr *)(icmph + 1);
      ipv6_addr_copy(addrp, target);
      addrp++;
      ipv6_addr_copy(addrp, &ipv6_hdr(skb)->daddr);

      opt = (u8*) (addrp + 1);

      /*
       *    include target_address option
       */

      if (ha)
            opt = ndisc_fill_addr_option(opt, ND_OPT_TARGET_LL_ADDR, ha,
                                   dev->addr_len, dev->type);

      /*
       *    build redirect option and copy skb over to the new packet.
       */

      memset(opt, 0, 8);
      *(opt++) = ND_OPT_REDIRECT_HDR;
      *(opt++) = (rd_len >> 3);
      opt += 6;

      memcpy(opt, ipv6_hdr(skb), rd_len - 8);

      icmph->icmp6_cksum = csum_ipv6_magic(&saddr_buf, &ipv6_hdr(skb)->saddr,
                                   len, IPPROTO_ICMPV6,
                                   csum_partial((u8 *) icmph, len, 0));

      buff->dst = dst;
      idev = in6_dev_get(dst->dev);
      IP6_INC_STATS(idev, IPSTATS_MIB_OUTREQUESTS);
      err = NF_HOOK(PF_INET6, NF_IP6_LOCAL_OUT, buff, NULL, dst->dev, dst_output);
      if (!err) {
            ICMP6MSGOUT_INC_STATS(idev, NDISC_REDIRECT);
            ICMP6_INC_STATS(idev, ICMP6_MIB_OUTMSGS);
      }

      if (likely(idev != NULL))
            in6_dev_put(idev);
}

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 (!pskb_may_pull(skb, skb->len))
            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_PRINTK2(KERN_WARNING
                     "ICMPv6 NDISC: invalid hop-limit: %d\n",
                     ipv6_hdr(skb)->hop_limit);
            return 0;
      }

      if (msg->icmph.icmp6_code != 0) {
            ND_PRINTK2(KERN_WARNING
                     "ICMPv6 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;

      if (dev->nd_net != &init_net)
            return NOTIFY_DONE;

      switch (event) {
      case NETDEV_CHANGEADDR:
            neigh_changeaddr(&nd_tbl, dev);
            fib6_run_gc(~0UL);
            break;
      case NETDEV_DOWN:
            neigh_ifdown(&nd_tbl, dev);
            fib6_run_gc(~0UL);
            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);
            printk(KERN_WARNING
                  "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, struct file * filp, 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, filp, buffer, lenp, ppos);

      else if (strcmp(ctl->procname, "base_reachable_time") == 0)
            ret = proc_dointvec_jiffies(ctl, write,
                                  filp, 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,
                                     filp, 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;
}

static int ndisc_ifinfo_sysctl_strategy(ctl_table *ctl, int __user *name,
                              int nlen, void __user *oldval,
                              size_t __user *oldlenp,
                              void __user *newval, size_t newlen)
{
      struct net_device *dev = ctl->extra1;
      struct inet6_dev *idev;
      int ret;

      if (ctl->ctl_name == NET_NEIGH_RETRANS_TIME ||
          ctl->ctl_name == NET_NEIGH_REACHABLE_TIME)
            ndisc_warn_deprecated_sysctl(ctl, "procfs", dev ? dev->name : "default");

      switch (ctl->ctl_name) {
      case NET_NEIGH_REACHABLE_TIME:
            ret = sysctl_jiffies(ctl, name, nlen,
                             oldval, oldlenp, newval, newlen);
            break;
      case NET_NEIGH_RETRANS_TIME_MS:
      case NET_NEIGH_REACHABLE_TIME_MS:
             ret = sysctl_ms_jiffies(ctl, name, nlen,
                               oldval, oldlenp, newval, newlen);
             break;
      default:
            ret = 0;
      }

      if (newval && newlen && ret > 0 &&
          dev && (idev = in6_dev_get(dev)) != NULL) {
            if (ctl->ctl_name == NET_NEIGH_REACHABLE_TIME ||
                ctl->ctl_name == NET_NEIGH_REACHABLE_TIME_MS)
                  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

int __init ndisc_init(struct net_proto_family *ops)
{
      struct ipv6_pinfo *np;
      struct sock *sk;
      int err;

      err = sock_create_kern(PF_INET6, SOCK_RAW, IPPROTO_ICMPV6, &ndisc_socket);
      if (err < 0) {
            ND_PRINTK0(KERN_ERR
                     "ICMPv6 NDISC: Failed to initialize the control socket (err %d).\n",
                     err);
            ndisc_socket = NULL; /* For safety. */
            return err;
      }

      sk = ndisc_socket->sk;
      np = inet6_sk(sk);
      sk->sk_allocation = GFP_ATOMIC;
      np->hop_limit = 255;
      /* Do not loopback ndisc messages */
      np->mc_loop = 0;
      sk->sk_prot->unhash(sk);

      /*
       * Initialize the neighbour table
       */

      neigh_table_init(&nd_tbl);

#ifdef CONFIG_SYSCTL
      neigh_sysctl_register(NULL, &nd_tbl.parms, NET_IPV6, NET_IPV6_NEIGH,
                        "ipv6",
                        &ndisc_ifinfo_sysctl_change,
                        &ndisc_ifinfo_sysctl_strategy);
#endif

      register_netdevice_notifier(&ndisc_netdev_notifier);
      return 0;
}

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);
      sock_release(ndisc_socket);
      ndisc_socket = NULL; /* For safety. */
}

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