This patch introduce different 6lowpan handling for receive and transmit
NS/NA messages for the ipv6 neighbour discovery. The first use-case is
for supporting 802.15.4 short addresses inside the option fields and
handling for RFC6775 6CO option field as userspace option.

Future handling:
Also add RS/RA(processing) for 802.15.4 short addresses and handle
RFC6775, which requires more 6lowpan specific handling for ipv6 neighbour
discovery implementation.

Cc: David S. Miller <da...@davemloft.net>
Cc: Alexey Kuznetsov <kuz...@ms2.inr.ac.ru>
Cc: James Morris <jmor...@namei.org>
Cc: Hideaki YOSHIFUJI <yoshf...@linux-ipv6.org>
Cc: Patrick McHardy <ka...@trash.net>
Signed-off-by: Alexander Aring <a...@pengutronix.de>
---
 include/net/ndisc.h     |   1 +
 net/6lowpan/6lowpan_i.h |   2 +
 net/6lowpan/Makefile    |   2 +-
 net/6lowpan/core.c      |   2 +
 net/6lowpan/ndisc.c     | 633 ++++++++++++++++++++++++++++++++++++++++++++++++
 net/ipv6/ndisc.c        |   3 +
 6 files changed, 642 insertions(+), 1 deletion(-)
 create mode 100644 net/6lowpan/ndisc.c

diff --git a/include/net/ndisc.h b/include/net/ndisc.h
index 35a4396..e2ee83d 100644
--- a/include/net/ndisc.h
+++ b/include/net/ndisc.h
@@ -35,6 +35,7 @@ enum {
        ND_OPT_ROUTE_INFO = 24,         /* RFC4191 */
        ND_OPT_RDNSS = 25,              /* RFC5006 */
        ND_OPT_DNSSL = 31,              /* RFC6106 */
+       ND_OPT_6CO = 34,                /* RFC6775 */
        __ND_OPT_MAX
 };
 
diff --git a/net/6lowpan/6lowpan_i.h b/net/6lowpan/6lowpan_i.h
index 97ecc27..8b01774 100644
--- a/net/6lowpan/6lowpan_i.h
+++ b/net/6lowpan/6lowpan_i.h
@@ -12,6 +12,8 @@ static inline bool lowpan_is_ll(const struct net_device *dev,
        return lowpan_dev(dev)->lltype == lltype;
 }
 
+void lowpan_register_ndisc_ops(struct net_device *dev);
+
 #ifdef CONFIG_6LOWPAN_DEBUGFS
 int lowpan_dev_debugfs_init(struct net_device *dev);
 void lowpan_dev_debugfs_exit(struct net_device *dev);
diff --git a/net/6lowpan/Makefile b/net/6lowpan/Makefile
index e44f3bf..12d131a 100644
--- a/net/6lowpan/Makefile
+++ b/net/6lowpan/Makefile
@@ -1,6 +1,6 @@
 obj-$(CONFIG_6LOWPAN) += 6lowpan.o
 
-6lowpan-y := core.o iphc.o nhc.o
+6lowpan-y := core.o iphc.o nhc.o ndisc.o
 6lowpan-$(CONFIG_6LOWPAN_DEBUGFS) += debugfs.o
 
 #rfc6282 nhcs
diff --git a/net/6lowpan/core.c b/net/6lowpan/core.c
index 824d1bc..e7a370e 100644
--- a/net/6lowpan/core.c
+++ b/net/6lowpan/core.c
@@ -34,6 +34,8 @@ int lowpan_register_netdevice(struct net_device *dev,
        for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++)
                lowpan_dev(dev)->ctx.table[i].id = i;
 
+       lowpan_register_ndisc_ops(dev);
+
        ret = register_netdevice(dev);
        if (ret < 0)
                return ret;
diff --git a/net/6lowpan/ndisc.c b/net/6lowpan/ndisc.c
new file mode 100644
index 0000000..d088295
--- /dev/null
+++ b/net/6lowpan/ndisc.c
@@ -0,0 +1,633 @@
+/* This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <net/6lowpan.h>
+#include <net/addrconf.h>
+#include <net/ip6_route.h>
+#include <net/ndisc.h>
+
+#include "6lowpan_i.h"
+
+struct lowpan_ndisc_options {
+       struct nd_opt_hdr *nd_opt_array[ND_OPT_TARGET_LL_ADDR + 1];
+#if IS_ENABLED(CONFIG_IEEE802154_6LOWPAN)
+       struct nd_opt_hdr *nd_802154_opt_array[ND_OPT_TARGET_LL_ADDR + 1];
+#endif
+};
+
+#define nd_802154_opts_src_lladdr      
nd_802154_opt_array[ND_OPT_SOURCE_LL_ADDR]
+#define nd_802154_opts_tgt_lladdr      
nd_802154_opt_array[ND_OPT_TARGET_LL_ADDR]
+
+#define NDISC_802154_EXTENDED_ADDR_LENGTH      2
+#define NDISC_802154_SHORT_ADDR_LENGTH         1
+
+#if IS_ENABLED(CONFIG_IEEE802154_6LOWPAN)
+static void lowpan_ndisc_802154_neigh_update(struct neighbour *n, void *priv,
+                                            bool override)
+{
+       struct lowpan_802154_neigh *neigh = 
lowpan_802154_neigh(neighbour_priv(n));
+
+       if (!override)
+               return;
+
+       write_lock_bh(&n->lock);
+       if (priv)
+               ieee802154_be16_to_le16(&neigh->short_addr, priv);
+       else
+               neigh->short_addr = cpu_to_le16(IEEE802154_ADDR_SHORT_UNSPEC);
+       write_unlock_bh(&n->lock);
+}
+
+static inline int lowpan_ndisc_802154_short_addr_space(struct net_device *dev)
+{
+       struct wpan_dev *wpan_dev;
+       int addr_space = 0;
+
+       if (lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154)) {
+               wpan_dev = lowpan_802154_dev(dev)->wdev->ieee802154_ptr;
+
+               if (ieee802154_is_valid_src_short_addr(wpan_dev->short_addr))
+                       addr_space = ndisc_opt_addr_space(dev, 
IEEE802154_SHORT_ADDR_LEN);
+       }
+
+       return addr_space;
+}
+
+static inline void
+lowpan_ndisc_802154_short_addr_option(struct net_device *dev,
+                                     struct sk_buff *skb, int type)
+{
+       struct wpan_dev *wpan_dev;
+       __be16 short_addr;
+
+       if (lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154)) {
+               wpan_dev = lowpan_802154_dev(dev)->wdev->ieee802154_ptr;
+
+               if (ieee802154_is_valid_src_short_addr(wpan_dev->short_addr)) {
+                       ieee802154_le16_to_be16(&short_addr,
+                                               &wpan_dev->short_addr);
+                       ndisc_fill_addr_option(skb, type, &short_addr,
+                                              IEEE802154_SHORT_ADDR_LEN);
+               }
+       }
+}
+#else
+static void
+lowpan_ndisc_802154_neigh_update(struct neighbour *n, void *priv,
+                                bool override) { }
+
+static inline void
+lowpan_ndisc_802154_short_addr_option(struct net_device *dev,
+                                     struct sk_buff *skb,
+                                     int type) { }
+
+static inline int lowpan_ndisc_802154_short_addr_space(struct net_device *dev)
+{
+       return 0;
+}
+#endif
+
+static void lowpan_ndisc_parse_addr_options(const struct net_device *dev,
+                                           struct lowpan_ndisc_options *ndopts,
+                                           struct nd_opt_hdr *nd_opt)
+{
+       switch (nd_opt->nd_opt_len) {
+       case NDISC_802154_EXTENDED_ADDR_LENGTH:
+               if (ndopts->nd_opt_array[nd_opt->nd_opt_type])
+                       ND_PRINTK(2, warn,
+                                 "%s: duplicated extended addr 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;
+#if IS_ENABLED(CONFIG_IEEE802154_6LOWPAN)
+       case NDISC_802154_SHORT_ADDR_LENGTH:
+               /* only valid on 802.15.4 */
+               if (!lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154)) {
+                       ND_PRINTK(2, warn,
+                                 "%s: invalid length detected: type=%d\n",
+                                 __func__, nd_opt->nd_opt_type);
+                       break;
+               }
+
+               if (ndopts->nd_802154_opt_array[nd_opt->nd_opt_type])
+                       ND_PRINTK(2, warn,
+                                 "%s: duplicated short addr ND6 option found: 
type=%d\n",
+                                 __func__, nd_opt->nd_opt_type);
+               else
+                       ndopts->nd_802154_opt_array[nd_opt->nd_opt_type] = 
nd_opt;
+               break;
+#endif
+       default:
+               ND_PRINTK(2, warn,
+                         "%s: invalid length detected: type=%d\n",
+                         __func__, nd_opt->nd_opt_type);
+               break;
+       }
+}
+
+static struct lowpan_ndisc_options *
+lowpan_ndisc_parse_options(const struct net_device *dev, u8 *opt, int opt_len,
+                          struct lowpan_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:
+                       lowpan_ndisc_parse_addr_options(dev, ndopts, nd_opt);
+                       break;
+               default:
+                       /* 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;
+}
+
+static void lowpan_ndisc_send_na(struct net_device *dev,
+                                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 = false;
+               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, dev->addr_len);
+               optlen += lowpan_ndisc_802154_short_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, dev->addr_len);
+               lowpan_ndisc_802154_short_addr_option(dev, skb,
+                                                     ND_OPT_TARGET_LL_ADDR);
+       }
+
+       ndisc_send_skb(skb, daddr, src_addr);
+}
+
+static void lowpan_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;
+       const struct in6_addr *daddr = &ipv6_hdr(skb)->daddr;
+       u8 *lladdr = NULL;
+       u32 ndoptlen = skb_tail_pointer(skb) - (skb_transport_header(skb) +
+                                   offsetof(struct nd_msg, opt));
+       struct lowpan_ndisc_options ndopts;
+       struct net_device *dev = skb->dev;
+       struct inet6_dev *idev = __in6_dev_get(dev);
+       struct inet6_ifaddr *ifp;
+       struct neighbour *neigh;
+       u8 *lladdr_short = NULL;
+
+       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;
+       }
+
+       /* For some 802.11 wireless deployments (and possibly other networks),
+        * there will be a NA proxy and unsolicitd packets are attacks
+        * and thus should not be accepted.
+        */
+       if (!msg->icmph.icmp6_solicited && idev &&
+           idev->cnf.drop_unsolicited_na)
+               return;
+
+       if (!lowpan_ndisc_parse_options(dev, 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,
+                                            dev->addr_len);
+               if (!lladdr) {
+                       ND_PRINTK(2, warn,
+                                 "NA: invalid link-layer address length\n");
+                       return;
+               }
+       }
+#if IS_ENABLED(CONFIG_IEEE802154_6LOWPAN)
+       if (lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154) &&
+           ndopts.nd_802154_opts_tgt_lladdr) {
+               lladdr_short = 
ndisc_opt_addr_data(ndopts.nd_802154_opts_tgt_lladdr,
+                                                  dev, 
IEEE802154_SHORT_ADDR_LEN);
+               if (!lladdr_short) {
+                       ND_PRINTK(2, warn,
+                                 "NA: invalid short link-layer address 
length\n");
+                       return;
+               }
+       }
+#endif
+       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 (lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154))
+                       lowpan_ndisc_802154_neigh_update(neigh, lladdr_short,
+                                                        
msg->icmph.icmp6_override);
+
+               if ((old_flags & ~neigh->flags) & NTF_ROUTER) {
+                       /* Change: router to host */
+                       rt6_clean_tohost(dev_net(dev),  saddr);
+               }
+
+out:
+               neigh_release(neigh);
+       }
+}
+
+static void lowpan_ndisc_send_ns(struct net_device *dev,
+                                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) {
+               if (ipv6_get_lladdr(dev, &addr_buf,
+                                   (IFA_F_TENTATIVE | IFA_F_OPTIMISTIC)))
+                       return;
+               saddr = &addr_buf;
+       }
+
+       if (ipv6_addr_any(saddr))
+               inc_opt = false;
+       if (inc_opt) {
+               optlen += ndisc_opt_addr_space(dev, dev->addr_len);
+               optlen += lowpan_ndisc_802154_short_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, dev->addr_len);
+               lowpan_ndisc_802154_short_addr_option(dev, skb,
+                                                     ND_OPT_SOURCE_LL_ADDR);
+       }
+
+       ndisc_send_skb(skb, daddr, saddr);
+}
+
+static void lowpan_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_pointer(skb) - (skb_transport_header(skb) +
+                                   offsetof(struct nd_msg, opt));
+       struct lowpan_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;
+       u8 *lladdr_short = NULL;
+
+       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 (!lowpan_ndisc_parse_options(dev, 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,
+                                            dev->addr_len);
+               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;
+               }
+       }
+
+#if IS_ENABLED(CONFIG_IEEE802154_6LOWPAN)
+       if (lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154) &&
+           ndopts.nd_802154_opts_src_lladdr) {
+               lladdr_short = 
ndisc_opt_addr_data(ndopts.nd_802154_opts_src_lladdr,
+                                                  dev, 
IEEE802154_SHORT_ADDR_LEN);
+               if (!lladdr_short) {
+                       ND_PRINTK(2, warn,
+                                 "NS: invalid short 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 (short link-layer address 
option)\n");
+                       return;
+               }
+       }
+#endif
+
+       inc = ipv6_addr_is_multicast(daddr);
+
+       ifp = ipv6_get_ifaddr(dev_net(dev), &msg->target, dev, 1);
+       if (ifp) {
+have_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;
+                       }
+
+                       /* 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);
+
+               /* perhaps an address on the master device */
+               if (netif_is_l3_slave(dev)) {
+                       struct net_device *mdev;
+
+                       mdev = netdev_master_upper_dev_get_rcu(dev);
+                       if (mdev) {
+                               ifp = ipv6_get_ifaddr(net, &msg->target, mdev, 
1);
+                               if (ifp)
+                                       goto have_ifp;
+                       }
+               }
+
+               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 &&
+                           NEIGH_VAR(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, &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 (lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154))
+                       lowpan_ndisc_802154_neigh_update(neigh, lladdr_short,
+                                                        true);
+       }
+       if (neigh || !dev->header_ops) {
+               ndisc_send_na(dev, 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 inline int lowpan_ndisc_is_useropt(struct nd_opt_hdr *opt)
+{
+       return __ip6_ndisc_is_useropt(opt) || opt->nd_opt_type == ND_OPT_6CO;
+}
+
+static const struct ndisc_ops lowpan_ndisc_ops = {
+       .is_useropt = lowpan_ndisc_is_useropt,
+       .send_na = lowpan_ndisc_send_na,
+       .recv_na = lowpan_ndisc_recv_na,
+       .send_ns = lowpan_ndisc_send_ns,
+       .recv_ns = lowpan_ndisc_recv_ns,
+};
+
+void lowpan_register_ndisc_ops(struct net_device *dev)
+{
+       dev->ndisc_ops = &lowpan_ndisc_ops;
+}
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index dc8bfec..9d7f228 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1792,6 +1792,9 @@ static const struct ndisc_ops ip6_ndisc_ops = {
 void ip6_register_ndisc_ops(struct net_device *dev)
 {
        switch (dev->type) {
+       case ARPHRD_6LOWPAN:
+               /* will be assigned while lowpan interface register */
+               break;
        default:
                if (dev->ndisc_ops) {
                        ND_PRINTK(2, warn,
-- 
2.8.0

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