ipv6: protect protocols not handling ipv4 from v4 connection/bind attempts

Some ipv6 protocols cannot handle ipv4 addresses, so we must not allow
connecting and binding to them. sendmsg logic does already check msg->name
for this but must trust already connected sockets which could be set up
for connection to ipv4 address family.

Per-socket flag ipv6only is of no use here, as it is under users control
by setsockopt.

Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
index 94a3d04..fb9beb7 100644
--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c
@@ -31,7 +31,7 @@
 	.owner =	THIS_MODULE,
 	.init =		ping_init_sock,
 	.close =	ping_close,
-	.connect =	ip6_datagram_connect,
+	.connect =	ip6_datagram_connect_v6_only,
 	.disconnect =	udp_disconnect,
 	.setsockopt =	ipv6_setsockopt,
 	.getsockopt =	ipv6_getsockopt,