Commit bd329e12 authored Oct 22, 2012 by Bjørn Mork Committed by David S. Miller Oct 23, 2012

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>

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);

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