sctp: support non-blocking version of the new sctp_connectx() API

Prior implementation of the new sctp_connectx() call that returns
an association ID did not work correctly on non-blocking socket.
This is because we could not return both a EINPROGRESS error and
an association id.  This is a new implementation that supports this.

Originally from Ivan Skytte Jørgensen <isj-sctp@i1.dk

Signed-off-by: Ivan Skytte Jørgensen <isj-sctp@i1.dk
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>

include/net/sctp/user.h

@@ -147,6 +147,8 @@ enum sctp_optname {
 #define SCTP_GET_LOCAL_ADDRS	SCTP_GET_LOCAL_ADDRS
 	SCTP_SOCKOPT_CONNECTX, /* CONNECTX requests. */
 #define SCTP_SOCKOPT_CONNECTX	SCTP_SOCKOPT_CONNECTX
+	SCTP_SOCKOPT_CONNECTX3, /* CONNECTX requests. (new implementation) */
+#define SCTP_SOCKOPT_CONNECTX3	SCTP_SOCKOPT_CONNECTX3
 };
 
 /*

net/sctp/associola.c

@@ -1470,6 +1470,10 @@ int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
 {
 	int assoc_id;
 	int error = 0;
+
+	/* If the id is already assigned, keep it. */
+	if (asoc->assoc_id)
+		return error;
 retry:
 	if (unlikely(!idr_pre_get(&sctp_assocs_id, gfp)))
 		return -ENOMEM;

net/sctp/socket.c

@@ -1100,6 +1100,15 @@ static int __sctp_connect(struct sock* sk,
 		goto out_free;
 	}
 
+	/* In case the user of sctp_connectx() wants an association
+	 * id back, assign one now.
+	 */
+	if (assoc_id) {
+		err = sctp_assoc_set_id(asoc, GFP_KERNEL);
+		if (err < 0)
+			goto out_free;
+	}
+
 	err = sctp_primitive_ASSOCIATE(asoc, NULL);
 	if (err < 0) {
 		goto out_free;
@@ -1120,7 +1129,7 @@ static int __sctp_connect(struct sock* sk,
 	timeo = sock_sndtimeo(sk, f_flags & O_NONBLOCK);
 
 	err = sctp_wait_for_connect(asoc, &timeo);
-	if (!err && assoc_id)
+	if ((err == 0 || err == -EINPROGRESS) && assoc_id)
 		*assoc_id = asoc->assoc_id;
 
 	/* Don't free association on exit. */
@@ -1264,6 +1273,34 @@ SCTP_STATIC int sctp_setsockopt_connectx(struct sock* sk,
 		return assoc_id;
 }
 
+/*
+ * New (hopefully final) interface for the API.  The option buffer is used
+ * both for the returned association id and the addresses.
+ */
+SCTP_STATIC int sctp_getsockopt_connectx3(struct sock* sk, int len,
+					char __user *optval,
+					int __user *optlen)
+{
+	sctp_assoc_t assoc_id = 0;
+	int err = 0;
+
+	if (len < sizeof(assoc_id))
+		return -EINVAL;
+
+	err = __sctp_setsockopt_connectx(sk,
+			(struct sockaddr __user *)(optval + sizeof(assoc_id)),
+			len - sizeof(assoc_id), &assoc_id);
+
+	if (err == 0 || err == -EINPROGRESS) {
+		if (copy_to_user(optval, &assoc_id, sizeof(assoc_id)))
+			return -EFAULT;
+		if (put_user(sizeof(assoc_id), optlen))
+			return -EFAULT;
+	}
+
+	return err;
+}
+
 /* API 3.1.4 close() - UDP Style Syntax
  * Applications use close() to perform graceful shutdown (as described in
  * Section 10.1 of [SCTP]) on ALL the associations currently represented
@@ -5578,6 +5615,9 @@ SCTP_STATIC int sctp_getsockopt(struct sock *sk, int level, int optname,
 		retval = sctp_getsockopt_local_addrs(sk, len, optval,
 						     optlen);
 		break;
+	case SCTP_SOCKOPT_CONNECTX3:
+		retval = sctp_getsockopt_connectx3(sk, len, optval, optlen);
+		break;
 	case SCTP_DEFAULT_SEND_PARAM:
 		retval = sctp_getsockopt_default_send_param(sk, len,
 							    optval, optlen);