sctp: pass a kernel pointer to sctp_setsockopt_auth_supported

Use the kernel pointer that sctp_setsockopt has available instead of
directly handling the user pointer.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sctp/socket.c

@@ -4326,29 +4326,23 @@ static int sctp_setsockopt_asconf_supported(struct sock *sk,
 }
 
 static int sctp_setsockopt_auth_supported(struct sock *sk,
-					  char __user *optval,
+					  struct sctp_assoc_value *params,
 					  unsigned int optlen)
 {
-	struct sctp_assoc_value params;
 	struct sctp_association *asoc;
 	struct sctp_endpoint *ep;
 	int retval = -EINVAL;
 
-	if (optlen != sizeof(params))
-		goto out;
-
-	if (copy_from_user(&params, optval, optlen)) {
-		retval = -EFAULT;
+	if (optlen != sizeof(*params))
 		goto out;
-	}
 
-	asoc = sctp_id2assoc(sk, params.assoc_id);
-	if (!asoc && params.assoc_id != SCTP_FUTURE_ASSOC &&
+	asoc = sctp_id2assoc(sk, params->assoc_id);
+	if (!asoc && params->assoc_id != SCTP_FUTURE_ASSOC &&
 	    sctp_style(sk, UDP))
 		goto out;
 
 	ep = sctp_sk(sk)->ep;
-	if (params.assoc_value) {
+	if (params->assoc_value) {
 		retval = sctp_auth_init(ep, GFP_KERNEL);
 		if (retval)
 			goto out;
@@ -4358,7 +4352,7 @@ static int sctp_setsockopt_auth_supported(struct sock *sk,
 		}
 	}
 
-	ep->auth_enable = !!params.assoc_value;
+	ep->auth_enable = !!params->assoc_value;
 	retval = 0;
 
 out:
@@ -4638,7 +4632,7 @@ static int sctp_setsockopt(struct sock *sk, int level, int optname,
 		retval = sctp_setsockopt_asconf_supported(sk, kopt, optlen);
 		break;
 	case SCTP_AUTH_SUPPORTED:
-		retval = sctp_setsockopt_auth_supported(sk, optval, optlen);
+		retval = sctp_setsockopt_auth_supported(sk, kopt, optlen);
 		break;
 	case SCTP_ECN_SUPPORTED:
 		retval = sctp_setsockopt_ecn_supported(sk, optval, optlen);