[PATCH bluetooth-next 09/10] 6lowpan: introduce 6lowpan-nd

[Alexander Aring <aar@pengutronix.de>]

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 <davem@davemloft.net>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: James Morris <jmorris@namei.org>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Patrick McHardy <kaber@trash.net>
Signed-off-by: Alexander Aring <aar@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 25ce092..a884c81 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..b6dc244
--- /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];
+#ifdef 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
+
+#ifdef 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;
+#ifdef 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;
+		}
+	}
+#ifdef 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;
+		}
+	}
+
+#ifdef 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