[PATCHv2 bluetooth-next 07/10] ipv6: introduce neighbour discovery ops

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

This patch introduces neighbour discovery ops callback structure. The
structure contains at first receive and transmit handling for NS/NA and
userspace option field functionality.

These callback offers 6lowpan different handling, such as 802.15.4 short
address handling or RFC6775 (Neighbor Discovery Optimization for IPv6 over
6LoWPANs).

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/linux/netdevice.h |  3 ++
 include/net/ndisc.h       | 96 +++++++++++++++++++++++++++++++++++++++++++----
 net/ipv6/addrconf.c       |  1 +
 net/ipv6/ndisc.c          | 71 ++++++++++++++++++++++++-----------
 net/ipv6/route.c          |  2 +-
 5 files changed, 144 insertions(+), 29 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 0052c42..bc60033 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1677,6 +1677,9 @@ struct net_device {
 #ifdef CONFIG_NET_L3_MASTER_DEV
 	const struct l3mdev_ops	*l3mdev_ops;
 #endif
+#if IS_ENABLED(CONFIG_IPV6)
+	const struct ndisc_ops *ndisc_ops;
+#endif
 
 	const struct header_ops *header_ops;
 
diff --git a/include/net/ndisc.h b/include/net/ndisc.h
index aac868e..14ed016 100644
--- a/include/net/ndisc.h
+++ b/include/net/ndisc.h
@@ -110,7 +110,8 @@ struct ndisc_options {
 
 #define NDISC_OPT_SPACE(len) (((len)+2+7)&~7)
 
-struct ndisc_options *ndisc_parse_options(u8 *opt, int opt_len,
+struct ndisc_options *ndisc_parse_options(const struct net_device *dev,
+					  u8 *opt, int opt_len,
 					  struct ndisc_options *ndopts);
 
 /*
@@ -173,6 +174,93 @@ static inline struct neighbour *__ipv6_neigh_lookup(struct net_device *dev, cons
 	return n;
 }
 
+static inline int __ip6_ndisc_is_useropt(struct nd_opt_hdr *opt)
+{
+	return opt->nd_opt_type == ND_OPT_RDNSS ||
+		opt->nd_opt_type == ND_OPT_DNSSL;
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+struct ndisc_ops {
+	int	(*is_useropt)(struct nd_opt_hdr *opt);
+	void	(*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);
+	void	(*recv_na)(struct sk_buff *skb);
+	void	(*send_ns)(struct net_device *dev,
+			   const struct in6_addr *solicit,
+			   const struct in6_addr *daddr,
+			   const struct in6_addr *saddr);
+	void	(*recv_ns)(struct sk_buff *skb);
+};
+
+static inline int ndisc_is_useropt(const struct net_device *dev,
+				   struct nd_opt_hdr *opt)
+{
+	if (likely(dev->ndisc_ops->is_useropt))
+		return dev->ndisc_ops->is_useropt(opt);
+	else
+		return 0;
+}
+
+static inline void 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)
+{
+	if (likely(dev->ndisc_ops->send_na))
+		dev->ndisc_ops->send_na(dev, daddr, solicited_addr, router,
+					solicited, override, inc_opt);
+}
+
+static inline void ndisc_recv_na(struct sk_buff *skb)
+{
+	if (likely(skb->dev->ndisc_ops->recv_na))
+		skb->dev->ndisc_ops->recv_na(skb);
+}
+
+static inline void ndisc_send_ns(struct net_device *dev,
+				 const struct in6_addr *solicit,
+				 const struct in6_addr *daddr,
+				 const struct in6_addr *saddr)
+{
+	if (likely(dev->ndisc_ops->send_ns))
+		dev->ndisc_ops->send_ns(dev, solicit, daddr, saddr);
+}
+
+static inline void ndisc_recv_ns(struct sk_buff *skb)
+{
+	if (likely(skb->dev->ndisc_ops->recv_ns))
+		skb->dev->ndisc_ops->recv_ns(skb);
+}
+#else
+static inline int ndisc_is_useropt(const struct net_device *dev,
+				   struct nd_opt_hdr *opt)
+{
+	return 0;
+}
+
+static inline void 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) { }
+
+static inline void ndisc_recv_na(struct sk_buff *skb) { }
+
+static inline void ndisc_send_ns(struct net_device *dev,
+				 const struct in6_addr *solicit,
+				 const struct in6_addr *daddr,
+				 const struct in6_addr *saddr) { }
+
+static inline void ndisc_recv_ns(struct sk_buff *skb) { }
+#endif
+
+void ip6_register_ndisc_ops(struct net_device *dev);
+
 int ndisc_init(void);
 int ndisc_late_init(void);
 
@@ -181,14 +269,8 @@ void ndisc_cleanup(void);
 
 int ndisc_rcv(struct sk_buff *skb);
 
-void ndisc_send_ns(struct net_device *dev, const struct in6_addr *solicit,
-		   const struct in6_addr *daddr, const struct in6_addr *saddr);
-
 void ndisc_send_rs(struct net_device *dev,
 		   const struct in6_addr *saddr, const struct in6_addr *daddr);
-void 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);
 
 void ndisc_send_redirect(struct sk_buff *skb, const struct in6_addr *target);
 
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 54e18c2..a2ef04b 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3266,6 +3266,7 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event,
 			idev = ipv6_add_dev(dev);
 			if (IS_ERR(idev))
 				return notifier_from_errno(PTR_ERR(idev));
+			ip6_register_ndisc_ops(dev);
 		}
 		break;
 
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 176c7c4..297080a 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -185,24 +185,25 @@ static struct nd_opt_hdr *ndisc_next_option(struct nd_opt_hdr *cur,
 	return cur <= end && cur->nd_opt_type == type ? cur : NULL;
 }
 
-static inline int ndisc_is_useropt(struct nd_opt_hdr *opt)
+static inline int ip6_ndisc_is_useropt(struct nd_opt_hdr *opt)
 {
-	return opt->nd_opt_type == ND_OPT_RDNSS ||
-		opt->nd_opt_type == ND_OPT_DNSSL;
+	return __ip6_ndisc_is_useropt(opt);
 }
 
-static struct nd_opt_hdr *ndisc_next_useropt(struct nd_opt_hdr *cur,
+static struct nd_opt_hdr *ndisc_next_useropt(const struct net_device *dev,
+					     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;
+	} while (cur < end && !ndisc_is_useropt(dev, cur));
+	return cur <= end && ndisc_is_useropt(dev, cur) ? cur : NULL;
 }
 
-struct ndisc_options *ndisc_parse_options(u8 *opt, int opt_len,
+struct ndisc_options *ndisc_parse_options(const struct net_device *dev,
+					  u8 *opt, int opt_len,
 					  struct ndisc_options *ndopts)
 {
 	struct nd_opt_hdr *nd_opt = (struct nd_opt_hdr *)opt;
@@ -243,7 +244,7 @@ struct ndisc_options *ndisc_parse_options(u8 *opt, int opt_len,
 			break;
 #endif
 		default:
-			if (ndisc_is_useropt(nd_opt)) {
+			if (ndisc_is_useropt(dev, nd_opt)) {
 				ndopts->nd_useropts_end = nd_opt;
 				if (!ndopts->nd_useropts)
 					ndopts->nd_useropts = nd_opt;
@@ -479,9 +480,11 @@ static void ndisc_send_skb(struct sk_buff *skb,
 	rcu_read_unlock();
 }
 
-void 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)
+static void ip6_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;
@@ -555,8 +558,10 @@ static void ndisc_send_unsol_na(struct net_device *dev)
 	in6_dev_put(idev);
 }
 
-void ndisc_send_ns(struct net_device *dev, const struct in6_addr *solicit,
-		   const struct in6_addr *daddr, const struct in6_addr *saddr)
+static void ip6_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;
@@ -702,7 +707,7 @@ static int pndisc_is_router(const void *pkey,
 	return ret;
 }
 
-static void ndisc_recv_ns(struct sk_buff *skb)
+static void ip6_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;
@@ -738,7 +743,7 @@ static void ndisc_recv_ns(struct sk_buff *skb)
 		return;
 	}
 
-	if (!ndisc_parse_options(msg->opt, ndoptlen, &ndopts)) {
+	if (!ndisc_parse_options(dev, msg->opt, ndoptlen, &ndopts)) {
 		ND_PRINTK(2, warn, "NS: invalid ND options\n");
 		return;
 	}
@@ -874,7 +879,7 @@ out:
 		in6_dev_put(idev);
 }
 
-static void ndisc_recv_na(struct sk_buff *skb)
+static void ip6_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;
@@ -912,7 +917,7 @@ static void ndisc_recv_na(struct sk_buff *skb)
 	    idev->cnf.drop_unsolicited_na)
 		return;
 
-	if (!ndisc_parse_options(msg->opt, ndoptlen, &ndopts)) {
+	if (!ndisc_parse_options(dev, msg->opt, ndoptlen, &ndopts)) {
 		ND_PRINTK(2, warn, "NS: invalid ND option\n");
 		return;
 	}
@@ -1019,7 +1024,7 @@ static void ndisc_recv_rs(struct sk_buff *skb)
 		goto out;
 
 	/* Parse ND options */
-	if (!ndisc_parse_options(rs_msg->opt, ndoptlen, &ndopts)) {
+	if (!ndisc_parse_options(skb->dev, rs_msg->opt, ndoptlen, &ndopts)) {
 		ND_PRINTK(2, notice, "NS: invalid ND option, ignored\n");
 		goto out;
 	}
@@ -1137,7 +1142,7 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 		return;
 	}
 
-	if (!ndisc_parse_options(opt, optlen, &ndopts)) {
+	if (!ndisc_parse_options(skb->dev, opt, optlen, &ndopts)) {
 		ND_PRINTK(2, warn, "RA: invalid ND options\n");
 		return;
 	}
@@ -1424,7 +1429,8 @@ skip_routeinfo:
 		struct nd_opt_hdr *p;
 		for (p = ndopts.nd_useropts;
 		     p;
-		     p = ndisc_next_useropt(p, ndopts.nd_useropts_end)) {
+		     p = ndisc_next_useropt(skb->dev, p,
+					    ndopts.nd_useropts_end)) {
 			ndisc_ra_useropt(skb, p);
 		}
 	}
@@ -1462,7 +1468,7 @@ static void ndisc_redirect_rcv(struct sk_buff *skb)
 		return;
 	}
 
-	if (!ndisc_parse_options(msg->opt, ndoptlen, &ndopts))
+	if (!ndisc_parse_options(skb->dev, msg->opt, ndoptlen, &ndopts))
 		return;
 
 	if (!ndopts.nd_opts_rh) {
@@ -1783,6 +1789,29 @@ int ndisc_ifinfo_sysctl_change(struct ctl_table *ctl, int write, void __user *bu
 
 #endif
 
+static const struct ndisc_ops ip6_ndisc_ops = {
+	.is_useropt = ip6_ndisc_is_useropt,
+	.send_na = ip6_ndisc_send_na,
+	.recv_na = ip6_ndisc_recv_na,
+	.send_ns = ip6_ndisc_send_ns,
+	.recv_ns = ip6_ndisc_recv_ns,
+};
+
+void ip6_register_ndisc_ops(struct net_device *dev)
+{
+	switch (dev->type) {
+	default:
+		if (dev->ndisc_ops) {
+			ND_PRINTK(2, warn,
+				  "%s: ndisc_ops already defined for interface type=%d\n",
+				  __func__, dev->type);
+		} else {
+			dev->ndisc_ops = &ip6_ndisc_ops;
+		}
+		break;
+	}
+}
+
 static int __net_init ndisc_net_init(struct net *net)
 {
 	struct ipv6_pinfo *np;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index cc180b3..5fa276d 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2149,7 +2149,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
 	 *	first-hop router for the specified ICMP Destination Address.
 	 */
 
-	if (!ndisc_parse_options(msg->opt, optlen, &ndopts)) {
+	if (!ndisc_parse_options(skb->dev, msg->opt, optlen, &ndopts)) {
 		net_dbg_ratelimited("rt6_redirect: invalid ND options\n");
 		return;
 	}
-- 
2.8.0