[IPV6] NDISC: Don't rely on node-type hint from L2 unless required.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

include/linux/skbuff.h

@@ -313,7 +313,9 @@ struct sk_buff {
 	__u16			tc_verd;	/* traffic control verdict */
 #endif
 #endif
+#ifdef CONFIG_IPV6_NDISC_NODETYPE
 	__u8			ndisc_nodetype:2;
+#endif
 	/* 14 bit hole */
 
 #ifdef CONFIG_NET_DMA

net/ipv6/Kconfig

@@ -168,6 +168,7 @@ config IPV6_SIT
 	tristate "IPv6: IPv6-in-IPv4 tunnel (SIT driver)"
 	depends on IPV6
 	select INET_TUNNEL
+	select IPV6_NDISC_NODETYPE
 	default y
 	---help---
 	  Tunneling means encapsulating data of one protocol type within
@@ -178,6 +179,9 @@ config IPV6_SIT
 
 	  Saying M here will produce a module called sit.ko. If unsure, say Y.
 
+config IPV6_NDISC_NODETYPE
+	bool
+
 config IPV6_TUNNEL
 	tristate "IPv6: IP-in-IPv6 tunnel (RFC2473)"
 	select INET6_TUNNEL

net/ipv6/ndisc.c

@@ -1092,11 +1092,13 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 		return;
 	}
 
+#ifdef CONFIG_IPV6_NDISC_NODETYPE
 	if (skb->ndisc_nodetype == NDISC_NODETYPE_HOST) {
 		ND_PRINTK2(KERN_WARNING
 			   "ICMPv6 RA: from host or unauthorized router\n");
 		return;
 	}
+#endif
 
 	/*
 	 *	set the RA_RECV flag in the interface
@@ -1121,9 +1123,11 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 		return;
 	}
 
+#ifdef CONFIG_IPV6_NDISC_NODETYPE
 	/* skip link-specific parameters from interior routers */
 	if (skb->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT)
 		goto skip_linkparms;
+#endif
 
 	if (in6_dev->if_flags & IF_RS_SENT) {
 		/*
@@ -1239,7 +1243,9 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 		}
 	}
 
+#ifdef CONFIG_IPV6_NDISC_NODETYPE
 skip_linkparms:
+#endif
 
 	/*
 	 *	Process options.
@@ -1286,9 +1292,11 @@ static void ndisc_router_discovery(struct sk_buff *skb)
 	}
 #endif
 
+#ifdef CONFIG_IPV6_NDISC_NODETYPE
 	/* skip link-specific ndopts from interior routers */
 	if (skb->ndisc_nodetype == NDISC_NODETYPE_NODEFAULT)
 		goto out;
+#endif
 
 	if (in6_dev->cnf.accept_ra_pinfo && ndopts.nd_opts_pi) {
 		struct nd_opt_hdr *p;
@@ -1353,6 +1361,7 @@ static void ndisc_redirect_rcv(struct sk_buff *skb)
 	int optlen;
 	u8 *lladdr = NULL;
 
+#ifdef CONFIG_IPV6_NDISC_NODETYPE
 	switch (skb->ndisc_nodetype) {
 	case NDISC_NODETYPE_HOST:
 	case NDISC_NODETYPE_NODEFAULT:
@@ -1360,6 +1369,7 @@ static void ndisc_redirect_rcv(struct sk_buff *skb)
 			   "ICMPv6 Redirect: from host or unauthorized router\n");
 		return;
 	}
+#endif
 
 	if (!(ipv6_addr_type(&ipv6_hdr(skb)->saddr) & IPV6_ADDR_LINKLOCAL)) {
 		ND_PRINTK2(KERN_WARNING