Re: Forcing a USB device to "ugen"

[Taylor R Campbell <campbell+netbsd-tech-kern%mumble.net@localhost>]

> Date: Tue, 26 Mar 2024 17:41:52 -0400
> From: Thor Lancelot Simon <tls%panix.com@localhost>
> 
> On Tue, Mar 26, 2024 at 12:25:07AM +0000, Taylor R Campbell wrote:
> > 
> > We should really expose a /dev/ugen* instance for _every_ USB device;
> > those that have kernel drivers attached have only limited access via
> > /dev/ugen* (no reads, writes, transfer ioctls, &c.), until you do
> > ioctl(USB_KICK_OUT_KERNEL_DRIVER) or whatever, at which point the
> > kernel driver will detach and the user program can take over instead
> > and use the full ugen(4) API.
> 
> I don't think this can be safely allowed at security level > 0, unless,
> perhaps, it's restricted from working on devices that would match disk
> drivers.

ioctl(USB_KICK_OUT_KERNEL_DRIVER) would attempt to detach the driver
without DETACH_FORCE, so disk devices with file systems mounted would
simply decline and the ioctl would fail.