path: root/Documentation/usb/authorization.txt
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Diffstat (limited to 'Documentation/usb/authorization.txt')
1 files changed, 31 insertions, 0 deletions
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
+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.
+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.