[NET]: Disable netfilter sockopts when not in the initial network namespace

Until we support multiple network namespaces with netfilter only allow
netfilter configuration in the initial network namespace.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/netfilter/nf_sockopt.c

@@ -69,6 +69,9 @@ static int nf_sockopt(struct sock *sk, int pf, int val,
 	struct nf_sockopt_ops *ops;
 	int ret;
 
+	if (sk->sk_net != &init_net)
+		return -ENOPROTOOPT;
+
 	if (mutex_lock_interruptible(&nf_sockopt_mutex) != 0)
 		return -EINTR;
 
@@ -125,6 +128,10 @@ static int compat_nf_sockopt(struct sock *sk, int pf, int val,
 	struct nf_sockopt_ops *ops;
 	int ret;
 
+	if (sk->sk_net != &init_net)
+		return -ENOPROTOOPT;
+
+
 	if (mutex_lock_interruptible(&nf_sockopt_mutex) != 0)
 		return -EINTR;