6lowpan: add 802.15.4 short addr slaac

This patch adds the autoconfiguration if a valid 802.15.4 short address
is available for 802.15.4 6LoWPAN interfaces.

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>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Reviewed-by: Stefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: Alexander Aring <aar@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/6lowpan.h

@@ -254,6 +254,12 @@ static inline bool lowpan_fetch_skb(struct sk_buff *skb, void *data,
 	return false;
 }
 
+static inline bool lowpan_802154_is_valid_src_short_addr(__le16 addr)
+{
+	/* First bit of addr is multicast, reserved or 802.15.4 specific */
+	return !(addr & cpu_to_le16(0x8000));
+}
+
 static inline void lowpan_push_hc_data(u8 **hc_ptr, const void *data,
 				       const size_t len)
 {

include/net/addrconf.h

@@ -94,6 +94,9 @@ int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
 void addrconf_join_solict(struct net_device *dev, const struct in6_addr *addr);
 void addrconf_leave_solict(struct inet6_dev *idev, const struct in6_addr *addr);
 
+void addrconf_add_linklocal(struct inet6_dev *idev,
+			    const struct in6_addr *addr, u32 flags);
+
 static inline int addrconf_ifid_eui48(u8 *eui, struct net_device *dev)
 {
 	if (dev->addr_len != ETH_ALEN)

net/6lowpan/core.c

@@ -14,6 +14,7 @@
 #include <linux/module.h>
 
 #include <net/6lowpan.h>
+#include <net/addrconf.h>
 
 #include "6lowpan_i.h"
 
@@ -72,16 +73,61 @@ void lowpan_unregister_netdev(struct net_device *dev)
 }
 EXPORT_SYMBOL(lowpan_unregister_netdev);
 
+static int addrconf_ifid_802154_6lowpan(u8 *eui, struct net_device *dev)
+{
+	struct wpan_dev *wpan_dev = lowpan_802154_dev(dev)->wdev->ieee802154_ptr;
+
+	/* Set short_addr autoconfiguration if short_addr is present only */
+	if (!lowpan_802154_is_valid_src_short_addr(wpan_dev->short_addr))
+		return -1;
+
+	/* For either address format, all zero addresses MUST NOT be used */
+	if (wpan_dev->pan_id == cpu_to_le16(0x0000) &&
+	    wpan_dev->short_addr == cpu_to_le16(0x0000))
+		return -1;
+
+	/* Alternatively, if no PAN ID is known, 16 zero bits may be used */
+	if (wpan_dev->pan_id == cpu_to_le16(IEEE802154_PAN_ID_BROADCAST))
+		memset(eui, 0, 2);
+	else
+		ieee802154_le16_to_be16(eui, &wpan_dev->pan_id);
+
+	/* The "Universal/Local" (U/L) bit shall be set to zero */
+	eui[0] &= ~2;
+	eui[2] = 0;
+	eui[3] = 0xFF;
+	eui[4] = 0xFE;
+	eui[5] = 0;
+	ieee802154_le16_to_be16(&eui[6], &wpan_dev->short_addr);
+	return 0;
+}
+
 static int lowpan_event(struct notifier_block *unused,
 			unsigned long event, void *ptr)
 {
 	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+	struct inet6_dev *idev;
+	struct in6_addr addr;
 	int i;
 
 	if (dev->type != ARPHRD_6LOWPAN)
 		return NOTIFY_DONE;
 
+	idev = __in6_dev_get(dev);
+	if (!idev)
+		return NOTIFY_DONE;
+
 	switch (event) {
+	case NETDEV_UP:
+	case NETDEV_CHANGE:
+		/* (802.15.4 6LoWPAN short address slaac handling */
+		if (lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154) &&
+		    addrconf_ifid_802154_6lowpan(addr.s6_addr + 8, dev) == 0) {
+			__ipv6_addr_set_half(&addr.s6_addr32[0],
+					     htonl(0xFE800000), 0);
+			addrconf_add_linklocal(idev, &addr, 0);
+		}
+		break;
 	case NETDEV_DOWN:
 		for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++)
 			clear_bit(LOWPAN_IPHC_CTX_FLAG_ACTIVE,

net/ipv6/addrconf.c

@@ -2947,8 +2947,8 @@ static void init_loopback(struct net_device *dev)
 	}
 }
 
-static void addrconf_add_linklocal(struct inet6_dev *idev,
-				   const struct in6_addr *addr, u32 flags)
+void addrconf_add_linklocal(struct inet6_dev *idev,
+			    const struct in6_addr *addr, u32 flags)
 {
 	struct inet6_ifaddr *ifp;
 	u32 addr_flags = flags | IFA_F_PERMANENT;
@@ -2967,6 +2967,7 @@ static void addrconf_add_linklocal(struct inet6_dev *idev,
 		in6_ifa_put(ifp);
 	}
 }
+EXPORT_SYMBOL_GPL(addrconf_add_linklocal);
 
 static bool ipv6_reserved_interfaceid(struct in6_addr address)
 {