net: cdc_ncm: do not bind to NCM compatible MBIM devices
The MBIM specification allows a MBIM device to disguise
itself as NCM for backwards compatibility, using additional
altsettings with different subclass (control) or protocol
(data):
C:* #Ifs= 2 Cfg#= 1 Atr=80 MxPwr=100mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=0d Prot=00 Driver=cdc_mbim
E: Ad=81(I) Atr=03(Int.) MxPS= 64 Ivl=7ms
I:* If#= 0 Alt= 1 #EPs= 1 Cls=02(comm.) Sub=0e Prot=00 Driver=cdc_mbim
E: Ad=81(I) Atr=03(Int.) MxPS= 64 Ivl=7ms
I: If#= 1 Alt= 0 #EPs= 0 Cls=0a(data ) Sub=00 Prot=01 Driver=cdc_mbim
I: If#= 1 Alt= 1 #EPs= 2 Cls=0a(data ) Sub=00 Prot=01 Driver=cdc_mbim
E: Ad=81(I) Atr=02(Bulk) MxPS= 64 Ivl=0ms
E: Ad=02(O) Atr=02(Bulk) MxPS= 64 Ivl=0ms
I:* If#= 1 Alt= 2 #EPs= 2 Cls=0a(data ) Sub=00 Prot=02 Driver=cdc_mbim
E: Ad=81(I) Atr=02(Bulk) MxPS= 64 Ivl=0ms
E: Ad=02(O) Atr=02(Bulk) MxPS= 64 Ivl=0ms
If the MBIM driver is enabled then that should have priority
for devices providing such a NCM 1.0 backward compatibility
mode.
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Greg Suarez <gsuarez@smithmicro.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/usb/cdc_ncm.c b/drivers/net/usb/cdc_ncm.c
index 17b4ba0..0ed03b1 100644
--- a/drivers/net/usb/cdc_ncm.c
+++ b/drivers/net/usb/cdc_ncm.c
@@ -563,6 +563,33 @@
{
int ret;
+ /* The MBIM spec defines a NCM compatible default altsetting,
+ * which we may have matched:
+ *
+ * "Functions that implement both NCM 1.0 and MBIM (an
+ * “NCM/MBIM function”) according to this recommendation
+ * shall provide two alternate settings for the
+ * Communication Interface. Alternate setting 0, and the
+ * associated class and endpoint descriptors, shall be
+ * constructed according to the rules given for the
+ * Communication Interface in section 5 of [USBNCM10].
+ * Alternate setting 1, and the associated class and
+ * endpoint descriptors, shall be constructed according to
+ * the rules given in section 6 (USB Device Model) of this
+ * specification."
+ *
+ * Do not bind to such interfaces, allowing cdc_mbim to handle
+ * them
+ */
+#if IS_ENABLED(CONFIG_USB_NET_CDC_MBIM)
+ if ((intf->num_altsetting == 2) &&
+ !usb_set_interface(dev->udev,
+ intf->cur_altsetting->desc.bInterfaceNumber,
+ CDC_NCM_COMM_ALTSETTING_MBIM) &&
+ cdc_ncm_comm_intf_is_mbim(intf->cur_altsetting))
+ return -ENODEV;
+#endif
+
/* NCM data altsetting is always 1 */
ret = cdc_ncm_bind_common(dev, intf, 1);