[SELINUX]: Fine-grained Netlink support - move security_netlink_send() hook.

This patch moves the security_netlink_send() LSM hook after the user copy,
so that LSM modules can safely examine skb payload content.  For SELinux,
we need to look at the Netlink message type.
Signed-off-by: James Morris <jmorris@redhat.com>
Signed-off-by: David S. Miller <davem@redhat.com>

net/netlink/af_netlink.c

@@ -728,14 +728,14 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock,
 	   to corresponding kernel module.   --ANK (980802)
 	 */
 
-	err = security_netlink_send(skb);
-	if (err) {
+	err = -EFAULT;
+	if (memcpy_fromiovec(skb_put(skb,len), msg->msg_iov, len)) {
 		kfree_skb(skb);
 		goto out;
 	}
 
-	err = -EFAULT;
-	if (memcpy_fromiovec(skb_put(skb,len), msg->msg_iov, len)) {
+	err = security_netlink_send(skb);
+	if (err) {
 		kfree_skb(skb);
 		goto out;
 	}