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Commit bd329e12 authored by Bjørn Mork's avatar Bjørn Mork Committed by David S. Miller
Browse files

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: default avatarBjørn Mork <bjorn@mork.no>
Signed-off-by: default avatarGreg Suarez <gsuarez@smithmicro.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9084ccf9

drivers/net/usb/cdc_ncm.c

+27 −0
Original line number Diff line number Diff line
@@ -563,6 +563,33 @@ static int cdc_ncm_bind(struct usbnet *dev, struct usb_interface *intf) 
{

	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);