[RFC 10/12] 6lowpan: introduce 6lowpan-nd

[Alexander Aring <aar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>]

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.

Cc: David S. Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
Cc: Alexey Kuznetsov <kuznet-v/Mj1YrvjDBInbfyfbPRSQ@public.gmane.org>
Cc: James Morris <jmorris-gx6/JNMH7DfYtjvyW6yDsg@public.gmane.org>
Cc: Hideaki YOSHIFUJI <yoshfuji-VfPWfsRibaP+Ru+s062T9g@public.gmane.org>
Cc: Patrick McHardy <kaber-dcUjhNyLwpNeoWH0uzbU5w@public.gmane.org>
Signed-off-by: Alexander Aring <aar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
---
 include/net/ndisc.h     |  18 ++--
 net/6lowpan/6lowpan_i.h |   4 +
 net/6lowpan/Makefile    |   2 +-
 net/6lowpan/core.c      |   4 +-
 net/6lowpan/ndisc.c     | 223 ++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 243 insertions(+), 8 deletions(-)
 create mode 100644 net/6lowpan/ndisc.c

diff --git a/include/net/ndisc.h b/include/net/ndisc.h
index c92ebdb..5299b52 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
 };
 
@@ -109,14 +110,19 @@ struct ndisc_options {
 #endif
 	struct nd_opt_hdr *nd_useropts;
 	struct nd_opt_hdr *nd_useropts_end;
+#if IS_ENABLED(CONFIG_IEEE802154_6LOWPAN)
+	struct nd_opt_hdr *nd_802154_opt_array[ND_OPT_TARGET_LL_ADDR + 1];
+#endif
 };
 
-#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 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 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_OPT_SPACE(len) (((len)+2+7)&~7)
 
diff --git a/net/6lowpan/6lowpan_i.h b/net/6lowpan/6lowpan_i.h
index 97ecc27..a67caee 100644
--- a/net/6lowpan/6lowpan_i.h
+++ b/net/6lowpan/6lowpan_i.h
@@ -12,6 +12,10 @@ static inline bool lowpan_is_ll(const struct net_device *dev,
 	return lowpan_dev(dev)->lltype == lltype;
 }
 
+extern const struct ndisc_ops lowpan_ndisc_ops;
+
+int addrconf_ifid_802154_6lowpan(u8 *eui, 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..3de7fd9 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;
 
+	dev->ndisc_ops = &lowpan_ndisc_ops;
+
 	ret = register_netdevice(dev);
 	if (ret < 0)
 		return ret;
@@ -73,7 +75,7 @@ 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)
+int addrconf_ifid_802154_6lowpan(u8 *eui, struct net_device *dev)
 {
 	struct wpan_dev *wpan_dev = lowpan_802154_dev(dev)->wdev->ieee802154_ptr;
 
diff --git a/net/6lowpan/ndisc.c b/net/6lowpan/ndisc.c
new file mode 100644
index 0000000..f67967b
--- /dev/null
+++ b/net/6lowpan/ndisc.c
@@ -0,0 +1,223 @@
+/* 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/ndisc.h>
+
+#include "6lowpan_i.h"
+
+static int lowpan_ndisc_is_useropt(u8 nd_opt_type)
+{
+	return nd_opt_type == ND_OPT_6CO;
+}
+
+#if IS_ENABLED(CONFIG_IEEE802154_6LOWPAN)
+#define NDISC_802154_SHORT_ADDR_LENGTH	1
+static int lowpan_ndisc_parse_addr_options(const struct net_device *dev,
+					   struct nd_opt_hdr *nd_opt,
+					   struct ndisc_options *ndopts)
+{
+	switch (nd_opt->nd_opt_len) {
+	case NDISC_802154_SHORT_ADDR_LENGTH:
+		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;
+		return 1;
+	default:
+		/* all others will be handled by ndisc IPv6 option parsing */
+		return 0;
+	}
+}
+
+static int lowpan_ndisc_parse_opts(const struct net_device *dev,
+				   struct nd_opt_hdr *nd_opt,
+				   struct ndisc_options *ndopts)
+{
+	switch (nd_opt->nd_opt_type) {
+	case ND_OPT_SOURCE_LL_ADDR:
+	case ND_OPT_TARGET_LL_ADDR:
+		return lowpan_ndisc_parse_addr_options(dev, nd_opt, ndopts);
+	default:
+		return 0;
+	}
+}
+
+static void lowpan_ndisc_802154_neigh_update(struct neighbour *n, u32 flags,
+					     u8 icmp6_type,
+					     const struct ndisc_options *ndopts)
+{
+	struct lowpan_802154_neigh *neigh = lowpan_802154_neigh(neighbour_priv(n));
+	u8 *lladdr_short = NULL;
+
+	switch (icmp6_type) {
+	case NDISC_ROUTER_SOLICITATION:
+	case NDISC_ROUTER_ADVERTISEMENT:
+	case NDISC_NEIGHBOUR_SOLICITATION:
+		if (ndopts->nd_802154_opts_src_lladdr) {
+			lladdr_short = ndisc_opt_addr_data(ndopts->nd_802154_opts_src_lladdr,
+							   IEEE802154_SHORT_ADDR_LEN, 0);
+			if (!lladdr_short) {
+				ND_PRINTK(2, warn,
+					  "NA: invalid short link-layer address length\n");
+				return;
+			}
+		}
+		break;
+	case NDISC_REDIRECT:
+	case NDISC_NEIGHBOUR_ADVERTISEMENT:
+		if (ndopts->nd_802154_opts_tgt_lladdr) {
+			lladdr_short = ndisc_opt_addr_data(ndopts->nd_802154_opts_tgt_lladdr,
+							   IEEE802154_SHORT_ADDR_LEN, 0);
+			if (!lladdr_short) {
+				ND_PRINTK(2, warn,
+					  "NA: invalid short link-layer address length\n");
+				return;
+			}
+		}
+		break;
+	default:
+		break;
+	}
+
+	write_lock_bh(&n->lock);
+	if (lladdr_short)
+		ieee802154_be16_to_le16(&neigh->short_addr, lladdr_short);
+	else
+		neigh->short_addr = cpu_to_le16(IEEE802154_ADDR_SHORT_UNSPEC);
+	write_unlock_bh(&n->lock);
+}
+
+static void lowpan_ndisc_neigh_update(const struct net_device *dev,
+				      struct neighbour *n, u32 flags,
+				      u8 icmp6_type,
+				      const struct ndisc_options *ndopts)
+{
+	/* react on overrides only. TODO check if this is really right. */
+	if (!lowpan_is_ll(dev, lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154)) ||
+	    ~flags & NEIGH_UPDATE_F_OVERRIDE)
+		return;
+
+	lowpan_ndisc_802154_neigh_update(n, flags, icmp6_type, ndopts);
+}
+
+static int lowpan_ndisc_opt_space(const struct net_device *dev, u8 icmp6_type,
+				  const struct neighbour *neigh, u8 *ha_buf,
+				  u8 **ha)
+{
+	struct lowpan_802154_neigh *n;
+	struct wpan_dev *wpan_dev;
+	int addr_space = 0;
+
+	if (!lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154))
+		return 0;
+
+	switch (icmp6_type) {
+	case NDISC_REDIRECT:
+		n = lowpan_802154_neigh(neighbour_priv(neigh));
+
+		if (ieee802154_is_valid_src_short_addr(n->short_addr)) {
+			memcpy(ha_buf, &n->short_addr,
+			       IEEE802154_SHORT_ADDR_LEN);
+			addr_space += ndisc_opt_addr_space(IEEE802154_SHORT_ADDR_LEN, 0);
+			*ha = ha_buf;
+		}
+		break;
+	case NDISC_NEIGHBOUR_ADVERTISEMENT:
+	case NDISC_NEIGHBOUR_SOLICITATION:
+	case NDISC_ROUTER_SOLICITATION:
+		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(IEEE802154_SHORT_ADDR_LEN, 0);
+		break;
+	default:
+		break;
+	}
+
+	return addr_space;
+}
+
+static void lowpan_ndisc_fill_opts(const struct net_device *dev,
+				   struct sk_buff *skb, u8 icmp6_type,
+				   const u8 *ha)
+{
+	struct wpan_dev *wpan_dev;
+	__be16 short_addr;
+	u8 opt_type;
+
+	if (!lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154))
+		return;
+
+	switch (icmp6_type) {
+	case NDISC_REDIRECT:
+		if (ha) {
+			ieee802154_le16_to_be16(&short_addr, ha);
+			ndisc_fill_addr_option(skb, ND_OPT_TARGET_LL_ADDR,
+					       &short_addr,
+					       IEEE802154_SHORT_ADDR_LEN, 0);
+		}
+		return;
+	case NDISC_NEIGHBOUR_ADVERTISEMENT:
+		opt_type = ND_OPT_TARGET_LL_ADDR;
+		break;
+	case NDISC_ROUTER_SOLICITATION:
+	case NDISC_NEIGHBOUR_SOLICITATION:
+		opt_type = ND_OPT_SOURCE_LL_ADDR;
+		break;
+	default:
+		return;
+	}
+
+	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, opt_type, &short_addr,
+				       IEEE802154_SHORT_ADDR_LEN, 0);
+	}
+}
+
+static void lowpan_ndisc_prefix_rcv_add_addr(struct net *net,
+					     struct net_device *dev,
+					     const struct prefix_info *pinfo,
+					     struct inet6_dev *in6_dev,
+					     struct in6_addr *addr,
+					     int addr_type, u32 addr_flags,
+					     bool sllao, bool tokenized,
+					     __u32 valid_lft,
+					     u32 prefered_lft,
+					     bool dev_addr_generated)
+{
+	/* generates short based address for RA PIO's */
+	if (lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154) && dev_addr_generated &&
+	    !addrconf_ifid_802154_6lowpan(addr->s6_addr + 8, dev)) {
+		addrconf_prefix_rcv_add_addr(net, dev, pinfo, in6_dev, addr,
+					     addr_type, addr_flags, sllao,
+					     tokenized, valid_lft,
+					     prefered_lft);
+	}
+}
+#endif
+
+const struct ndisc_ops lowpan_ndisc_ops = {
+	.is_useropt		= lowpan_ndisc_is_useropt,
+#if IS_ENABLED(CONFIG_IEEE802154_6LOWPAN)
+	.parse_opts		= lowpan_ndisc_parse_opts,
+	.neigh_update		= lowpan_ndisc_neigh_update,
+	.opt_space		= lowpan_ndisc_opt_space,
+	.fill_opts		= lowpan_ndisc_fill_opts,
+	.prefix_rcv_add_addr	= lowpan_ndisc_prefix_rcv_add_addr,
+#endif
+};
-- 
2.8.2