Bluetooth: Switch ATT channels to use L2CAP_CHAN_FIXED

ATT channels are not connection oriented so having them use
L2CAP_CHAN_CONN_ORIENTED is quite confusing. Instead, use the new
L2CAP_CHAN_FIXED type and ensure that the MTU and CID values get
properly set.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/l2cap_core.c

@@ -498,18 +498,10 @@ void __l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan)
 
 	switch (chan->chan_type) {
 	case L2CAP_CHAN_CONN_ORIENTED:
-		if (conn->hcon->type == LE_LINK) {
-			if (chan->dcid == L2CAP_CID_ATT) {
-				chan->omtu = L2CAP_DEFAULT_MTU;
-				chan->scid = L2CAP_CID_ATT;
-			} else {
-				chan->scid = l2cap_alloc_cid(conn);
-			}
-		} else {
 		/* Alloc CID for connection-oriented socket */
 		chan->scid = l2cap_alloc_cid(conn);
+		if (conn->hcon->type == ACL_LINK)
 			chan->omtu = L2CAP_DEFAULT_MTU;
-		}
 		break;
 
 	case L2CAP_CHAN_CONN_LESS:
@@ -7025,7 +7017,12 @@ int l2cap_chan_connect(struct l2cap_chan *chan, __le16 psm, u16 cid,
 		goto done;
 	}
 
-	if (chan->chan_type == L2CAP_CHAN_CONN_ORIENTED && !(psm || cid)) {
+	if (chan->chan_type == L2CAP_CHAN_CONN_ORIENTED && !psm) {
+		err = -EINVAL;
+		goto done;
+	}
+
+	if (chan->chan_type == L2CAP_CHAN_FIXED && !cid) {
 		err = -EINVAL;
 		goto done;
 	}

net/bluetooth/l2cap_sock.c

@@ -101,6 +101,15 @@ static int l2cap_sock_bind(struct socket *sock, struct sockaddr *addr, int alen)
 	if (!bdaddr_type_is_valid(la.l2_bdaddr_type))
 		return -EINVAL;
 
+	if (la.l2_cid) {
+		/* When the socket gets created it defaults to
+		 * CHAN_CONN_ORIENTED, so we need to overwrite the
+		 * default here.
+		 */
+		chan->chan_type = L2CAP_CHAN_FIXED;
+		chan->omtu = L2CAP_DEFAULT_MTU;
+	}
+
 	if (bdaddr_type_is_le(la.l2_bdaddr_type)) {
 		if (!enable_lecoc && la.l2_psm)
 			return -EINVAL;