Staging: usbip: Filtering illegal flags from remote driver

The usb_submit_urb function in debug mode monitors the bogus flags. The
client driver errors should not be conveyed to the local USB device.

Signed-off-by: Endre Kollar <taxy443@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/usbip/stub_rx.c

@@ -424,6 +424,60 @@ static int get_pipe(struct stub_device *sdev, int epnum, int dir)
 	return 0;
 }
 
+static void masking_bogus_flags(struct urb *urb)
+{
+	int				xfertype;
+	struct usb_device		*dev;
+	struct usb_host_endpoint	*ep;
+	int				is_out;
+	unsigned int	allowed;
+
+	if (!urb || urb->hcpriv || !urb->complete)
+		return;
+	dev = urb->dev;
+	if ((!dev) || (dev->state < USB_STATE_UNAUTHENTICATED))
+		return;
+
+	ep = (usb_pipein(urb->pipe) ? dev->ep_in : dev->ep_out)
+			[usb_pipeendpoint(urb->pipe)];
+	if (!ep)
+		return;
+
+	xfertype = usb_endpoint_type(&ep->desc);
+	if (xfertype == USB_ENDPOINT_XFER_CONTROL) {
+		struct usb_ctrlrequest *setup =
+				(struct usb_ctrlrequest *) urb->setup_packet;
+
+		if (!setup)
+			return;
+		is_out = !(setup->bRequestType & USB_DIR_IN) ||
+				!setup->wLength;
+	} else {
+		is_out = usb_endpoint_dir_out(&ep->desc);
+	}
+
+	/* enforce simple/standard policy */
+	allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_SETUP_DMA_MAP |
+			URB_NO_INTERRUPT | URB_DIR_MASK | URB_FREE_BUFFER);
+	switch (xfertype) {
+	case USB_ENDPOINT_XFER_BULK:
+		if (is_out)
+			allowed |= URB_ZERO_PACKET;
+		/* FALLTHROUGH */
+	case USB_ENDPOINT_XFER_CONTROL:
+		allowed |= URB_NO_FSBR;	/* only affects UHCI */
+		/* FALLTHROUGH */
+	default:			/* all non-iso endpoints */
+		if (!is_out)
+			allowed |= URB_SHORT_NOT_OK;
+		break;
+	case USB_ENDPOINT_XFER_ISOC:
+		allowed |= URB_ISO_ASAP;
+		break;
+	}
+	urb->transfer_flags &= allowed;
+}
+
 static void stub_recv_cmd_submit(struct stub_device *sdev,
 				 struct usbip_header *pdu)
 {
@@ -490,6 +544,7 @@ static void stub_recv_cmd_submit(struct stub_device *sdev,
 	/* no need to submit an intercepted request, but harmless? */
 	tweak_special_requests(priv->urb);
 
+	masking_bogus_flags(priv->urb);
 	/* urb is now ready to submit */
 	ret = usb_submit_urb(priv->urb, GFP_KERNEL);