From 7f59c150ad9ae017abcff16775ccdd0bdefb963d Mon Sep 17 00:00:00 2001 From: Stefan Koch Date: Tue, 25 Aug 2015 21:10:10 +0200 Subject: usb: interface authorization: Documentation part This part adds the documentation for the interface authorization. Signed-off-by: Stefan Koch Signed-off-by: Greg Kroah-Hartman --- Documentation/usb/authorization.txt | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'Documentation/usb') diff --git a/Documentation/usb/authorization.txt b/Documentation/usb/authorization.txt index c069b6884c77..c7e985f05d8f 100644 --- a/Documentation/usb/authorization.txt +++ b/Documentation/usb/authorization.txt @@ -90,3 +90,34 @@ etc, but you get the idea. Anybody with access to a device gadget kit can fake descriptors and device info. Don't trust that. You are welcome. + +Interface authorization +----------------------- +There is a similar approach to allow or deny specific USB interfaces. +That allows to block only a subset of an USB device. + +Authorize an interface: +$ echo 1 > /sys/bus/usb/devices/INTERFACE/authorized + +Deauthorize an interface: +$ echo 0 > /sys/bus/usb/devices/INTERFACE/authorized + +The default value for new interfaces +on a particular USB bus can be changed, too. + +Allow interfaces per default: +$ echo 1 > /sys/bus/usb/devices/usbX/interface_authorized_default + +Deny interfaces per default: +$ echo 0 > /sys/bus/usb/devices/usbX/interface_authorized_default + +Per default the interface_authorized_default bit is 1. +So all interfaces would authorized per default. + +Note: +If a deauthorized interface will be authorized so the driver probing must +be triggered manually by writing INTERFACE to /sys/bus/usb/drivers_probe + +For drivers that need multiple interfaces all needed interfaces should be +authroized first. After that the drivers should be probed. +This avoids side effects. -- cgit v1.2.3