On Mon, 30 May 2011, Greg KH wrote: > On Mon, May 30, 2011 at 09:09:15AM +0200, Carl-Daniel Hailfinger wrote: > > USB treats all devices attached to a wireless USB host controller as > > unauthorized by default and all devices attached to a wired USB host > > controller as authorized by default. This default setting can be changed > > manually per host controller by setting authorized_default in sysfs, but > > only after the host controller is already active. > > AFAICS there is a race between userspace setting authorized_default on > > startup and the USB subsystem enumerating devices on the USB bus. If a > > USB device is already plugged into a wired USB host controller on > > startup, it may be marked as authorized (and thus accessed by the > > kernel/userspace) before userspace has a chance to set > > authorized_default on that host controller. This is undesirable in kiosk > > situations where the user may have access to the USB ports of a machine > > during startup. > > > > Add an "authorized_default" parameter to the usbcore module which has > > three settings: > > 0 is not authorized for all devices > > 1 is authorized for all devices > > 2 is authorized for all devices except wireless (default, old behaviour) > > Ick, who is going to remember that "2" is the "default" here? > > I understand this could be a problem, but could you think up a cleaner > interface for this? The parameter could become a boolean if case 1 is removed. After all, 0 and 2 seem to be the most important cases. > Also, any new kernel/user API, like this one, needs to be documentented > in Documentation/ABI/. Actually they should be mentioned in Documentation/kernel-parameters.txt. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
