selinux: cleanup error reporting in selinux_nlmsg_perm()

Convert audit_log() call to WARN_ONCE().

Rename "type=" to nlmsg_type=" to avoid confusion with the audit record
type.

Added "protocol=" to help track down which protocol (NETLINK_AUDIT?) was used
within the netlink protocol family.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[Rewrote the patch subject line]
Signed-off-by: Paul Moore <pmoore@redhat.com>

security/selinux/hooks.c

@@ -4727,10 +4727,9 @@ static int selinux_nlmsg_perm(struct sock *sk, struct sk_buff *skb)
 	err = selinux_nlmsg_lookup(sksec->sclass, nlh->nlmsg_type, &perm);
 	if (err) {
 		if (err == -EINVAL) {
-			audit_log(current->audit_context, GFP_KERNEL, AUDIT_SELINUX_ERR,
-				  "SELinux:  unrecognized netlink message"
-				  " type=%hu for sclass=%hu\n",
-				  nlh->nlmsg_type, sksec->sclass);
+			WARN_ONCE(1, "selinux_nlmsg_perm: unrecognized netlink message:"
+				  " protocol=%hu nlmsg_type=%hu sclass=%hu\n",
+				  sk->sk_protocol, nlh->nlmsg_type, sksec->sclass);
 			if (!selinux_enforcing || security_get_allow_unknown())
 				err = 0;
 		}