openvswitch: Don't validate IPv6 label masks.

When userspace doesn't provide a mask, OVS datapath generates a fully
unwildcarded mask for the flow by copying the flow and setting all bits
in all fields. For IPv6 label, this creates a mask that matches on the
upper 12 bits, causing the following error:

openvswitch: netlink: Invalid IPv6 flow label value (value=ffffffff, max=fffff)

This patch ignores the label validation check for masks, avoiding this
error.
Signed-off-by: Joe Stringer <joestringer@nicira.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/openvswitch/flow_netlink.c

@@ -690,7 +690,7 @@ static int ovs_key_from_nlattrs(struct sw_flow_match *match, u64 attrs,
 			return -EINVAL;
 		}
 
-		if (ipv6_key->ipv6_label & htonl(0xFFF00000)) {
+		if (!is_mask && ipv6_key->ipv6_label & htonl(0xFFF00000)) {
 			OVS_NLERR("IPv6 flow label %x is out of range (max=%x).\n",
 				  ntohl(ipv6_key->ipv6_label), (1 << 20) - 1);
 			return -EINVAL;