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>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index aab5f74e91e6..7704ea9502fd 100644
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -371,6 +371,9 @@ static int l2tp_ip6_connect(struct sock *sk, struct sockaddr *uaddr,
         if (addr_len < sizeof(*lsa))
                 return -EINVAL;
 
+        if (usin->sin6_family != AF_INET6)
+                return -EINVAL;
+
         addr_type = ipv6_addr_type(&usin->sin6_addr);
         if (addr_type & IPV6_ADDR_MULTICAST)
                 return -EINVAL;