[NETNS]: Allow to create sockets in non-initial namespace.

Allow to create sockets in the namespace if the protocol ok with this.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/af_inet.c

@@ -243,6 +243,23 @@ void build_ehash_secret(void)
 }
 EXPORT_SYMBOL(build_ehash_secret);
 
+static inline int inet_netns_ok(struct net *net, int protocol)
+{
+	int hash;
+	struct net_protocol *ipprot;
+
+	if (net == &init_net)
+		return 1;
+
+	hash = protocol & (MAX_INET_PROTOS - 1);
+	ipprot = rcu_dereference(inet_protos[hash]);
+
+	if (ipprot == NULL)
+		/* raw IP is OK */
+		return 1;
+	return ipprot->netns_ok;
+}
+
 /*
  *	Create an inet socket.
  */
@@ -259,9 +276,6 @@ static int inet_create(struct net *net, struct socket *sock, int protocol)
 	int try_loading_module = 0;
 	int err;
 
-	if (net != &init_net)
-		return -EAFNOSUPPORT;
-
 	if (sock->type != SOCK_RAW &&
 	    sock->type != SOCK_DGRAM &&
 	    !inet_ehash_secret)
@@ -320,6 +334,10 @@ static int inet_create(struct net *net, struct socket *sock, int protocol)
 	if (answer->capability > 0 && !capable(answer->capability))
 		goto out_rcu_unlock;
 
+	err = -EAFNOSUPPORT;
+	if (!inet_netns_ok(net, protocol))
+		goto out_rcu_unlock;
+
 	sock->ops = answer->ops;
 	answer_prot = answer->prot;
 	answer_no_check = answer->no_check;