net: gre: provide multicast mappings for ipv4 and ipv6

My commit 6d55cb9 (gre: fix hard header destination address checking) broke multicast. The reason is that ip_gre used to get ipgre_header() calls with zero destination if we have NOARP or multicast destination. Instead the actual target was decided at ipgre_tunnel_xmit() time based on per-protocol dissection. Instead of allowing the "abuse" of ->header() calls with invalid destination, this creates multicast mappings for ip_gre. This also fixes "ip neigh show nud noarp" to display the proper multicast mappings used by the gre device. Reported-by: Doug Kehn <[email protected]> Signed-off-by: Timo Teräs <[email protected]> Acked-by: Doug Kehn <[email protected]> Signed-off-by: David S. Miller <[email protected]>
bobihu · Mar 30, 2011 · 93ca3bb · 93ca3bb
1 parent 1459a3c
commit 93ca3bb
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Showing 4 changed files with 29 additions and 0 deletions.
diff --git a/include/net/if_inet6.h b/include/net/if_inet6.h
@@ -286,5 +286,21 @@ static inline void ipv6_ib_mc_map(const struct in6_addr *addr,
 	buf[9]  = broadcast[9];
 	memcpy(buf + 10, addr->s6_addr + 6, 10);
 }
+
+static inline int ipv6_ipgre_mc_map(const struct in6_addr *addr,
+				    const unsigned char *broadcast, char *buf)
+{
+	if ((broadcast[0] | broadcast[1] | broadcast[2] | broadcast[3]) != 0) {
+		memcpy(buf, broadcast, 4);
+	} else {
+		/* v4mapped? */
+		if ((addr->s6_addr32[0] | addr->s6_addr32[1] |
+		     (addr->s6_addr32[2] ^ htonl(0x0000ffff))) != 0)
+			return -EINVAL;
+		memcpy(buf, &addr->s6_addr32[3], 4);
+	}
+	return 0;
+}
+
 #endif
 #endif
diff --git a/include/net/ip.h b/include/net/ip.h
@@ -339,6 +339,14 @@ static inline void ip_ib_mc_map(__be32 naddr, const unsigned char *broadcast, ch
 	buf[16] = addr & 0x0f;
 }
 
+static inline void ip_ipgre_mc_map(__be32 naddr, const unsigned char *broadcast, char *buf)
+{
+	if ((broadcast[0] | broadcast[1] | broadcast[2] | broadcast[3]) != 0)
+		memcpy(buf, broadcast, 4);
+	else
+		memcpy(buf, &naddr, sizeof(naddr));
+}
+
 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 #include <linux/ipv6.h>
 #endif

diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
@@ -215,6 +215,9 @@ int arp_mc_map(__be32 addr, u8 *haddr, struct net_device *dev, int dir)
 	case ARPHRD_INFINIBAND:
 		ip_ib_mc_map(addr, dev->broadcast, haddr);
 		return 0;
+	case ARPHRD_IPGRE:
+		ip_ipgre_mc_map(addr, dev->broadcast, haddr);
+		return 0;
 	default:
 		if (dir) {
 			memcpy(haddr, dev->broadcast, dev->addr_len);

diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
@@ -341,6 +341,8 @@ int ndisc_mc_map(struct in6_addr *addr, char *buf, struct net_device *dev, int d
 	case ARPHRD_INFINIBAND:
 		ipv6_ib_mc_map(addr, dev->broadcast, buf);
 		return 0;
+	case ARPHRD_IPGRE:
+		return ipv6_ipgre_mc_map(addr, dev->broadcast, buf);
 	default:
 		if (dir) {
 			memcpy(buf, dev->broadcast, dev->addr_len);