[IPV4]: Enable use of 240/4 address space.

This short patch modifies the IPv4 networking to enable use of the
240.0.0.0/4 (aka "class-E") address space as propsed in the internet
draft draft-fuller-240space-00.txt.
Signed-off-by: NJan Engelhardt <jengelh@computergmbh.de>
Acked-by: NYOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/in.h

@@ -262,9 +262,10 @@ static inline bool ipv4_is_local_multicast(__be32 addr)
 	return (addr & htonl(0xffffff00)) == htonl(0xe0000000);
 }
 
-static inline bool ipv4_is_badclass(__be32 addr)
+static inline bool ipv4_is_lbcast(__be32 addr)
 {
-	return (addr & htonl(0xf0000000)) == htonl(0xf0000000);
+	/* limited broadcast */
+	return addr == INADDR_BROADCAST;
 }
 
 static inline bool ipv4_is_zeronet(__be32 addr)

include/net/addrconf.h

@@ -262,7 +262,7 @@ static inline int ipv6_isatap_eui64(u8 *eui, __be32 addr)
 		  ipv4_is_private_172(addr) || ipv4_is_test_192(addr) ||
 		  ipv4_is_anycast_6to4(addr) || ipv4_is_private_192(addr) ||
 		  ipv4_is_test_198(addr) || ipv4_is_multicast(addr) ||
-		  ipv4_is_badclass(addr)) ? 0x00 : 0x02;
+		  ipv4_is_lbcast(addr)) ? 0x00 : 0x02;
 	eui[1] = 0;
 	eui[2] = 0x5E;
 	eui[3] = 0xFE;

net/core/pktgen.c

@@ -2266,7 +2266,7 @@ static void mod_cur_headers(struct pktgen_dev *pkt_dev)
 
 					while (ipv4_is_loopback(s) ||
 					       ipv4_is_multicast(s) ||
-					       ipv4_is_badclass(s) ||
+					       ipv4_is_lbcast(s) ||
 					       ipv4_is_zeronet(s) ||
 					       ipv4_is_local_multicast(s)) {
 						t = random32() % (imx - imn) + imn;

net/ipv4/fib_frontend.c

@@ -176,7 +176,7 @@ static inline unsigned __inet_dev_addr_type(struct net *net,
 	unsigned ret = RTN_BROADCAST;
 	struct fib_table *local_table;
 
-	if (ipv4_is_zeronet(addr) || ipv4_is_badclass(addr))
+	if (ipv4_is_zeronet(addr) || ipv4_is_lbcast(addr))
 		return RTN_BROADCAST;
 	if (ipv4_is_multicast(addr))
 		return RTN_MULTICAST;

net/ipv4/route.c

@@ -1154,7 +1154,7 @@ void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw,
 		return;
 
 	if (new_gw == old_gw || !IN_DEV_RX_REDIRECTS(in_dev)
-	    || ipv4_is_multicast(new_gw) || ipv4_is_badclass(new_gw)
+	    || ipv4_is_multicast(new_gw) || ipv4_is_lbcast(new_gw)
 	    || ipv4_is_zeronet(new_gw))
 		goto reject_redirect;
 
@@ -1634,7 +1634,7 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 	if (in_dev == NULL)
 		return -EINVAL;
 
-	if (ipv4_is_multicast(saddr) || ipv4_is_badclass(saddr) ||
+	if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
 	    ipv4_is_loopback(saddr) || skb->protocol != htons(ETH_P_IP))
 		goto e_inval;
 
@@ -1891,7 +1891,7 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 	   by fib_lookup.
 	 */
 
-	if (ipv4_is_multicast(saddr) || ipv4_is_badclass(saddr) ||
+	if (ipv4_is_multicast(saddr) || ipv4_is_lbcast(saddr) ||
 	    ipv4_is_loopback(saddr))
 		goto martian_source;
 
@@ -1904,7 +1904,7 @@ static int ip_route_input_slow(struct sk_buff *skb, __be32 daddr, __be32 saddr,
 	if (ipv4_is_zeronet(saddr))
 		goto martian_source;
 
-	if (ipv4_is_badclass(daddr) || ipv4_is_zeronet(daddr) ||
+	if (ipv4_is_lbcast(daddr) || ipv4_is_zeronet(daddr) ||
 	    ipv4_is_loopback(daddr))
 		goto martian_destination;
 
@@ -2125,7 +2125,7 @@ static inline int __mkroute_output(struct rtable **result,
 		res->type = RTN_BROADCAST;
 	else if (ipv4_is_multicast(fl->fl4_dst))
 		res->type = RTN_MULTICAST;
-	else if (ipv4_is_badclass(fl->fl4_dst) || ipv4_is_zeronet(fl->fl4_dst))
+	else if (ipv4_is_lbcast(fl->fl4_dst) || ipv4_is_zeronet(fl->fl4_dst))
 		return -EINVAL;
 
 	if (dev_out->flags & IFF_LOOPBACK)
@@ -2276,7 +2276,7 @@ static int ip_route_output_slow(struct rtable **rp, const struct flowi *oldflp)
 	if (oldflp->fl4_src) {
 		err = -EINVAL;
 		if (ipv4_is_multicast(oldflp->fl4_src) ||
-		    ipv4_is_badclass(oldflp->fl4_src) ||
+		    ipv4_is_lbcast(oldflp->fl4_src) ||
 		    ipv4_is_zeronet(oldflp->fl4_src))
 			goto out;