Re: [PATCH 2/2] usb: Implement usb_revoke() BPF function - Greg Kroah-Hartman

From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Bastien Nocera <hadess@hadess.net>
Cc: linux-usb@vger.kernel.org, bpf@vger.kernel.org,
	Alan Stern <stern@rowland.harvard.edu>,
	Benjamin Tissoires <benjamin.tissoires@redhat.com>,
	Peter Hutterer <peter.hutterer@who-t.net>,
	"Eric W . Biederman" <ebiederm@xmission.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>
Subject: Re: [PATCH 2/2] usb: Implement usb_revoke() BPF function
Date: Thu, 18 Aug 2022 17:08:04 +0200	[thread overview]
Message-ID: <Yv5V1KWOQa5mnktE@kroah.com> (raw)
In-Reply-To: <fae7e35a920239fe2a35b6b967bd17e04af1e1b7.camel@hadess.net>

On Tue, Aug 09, 2022 at 07:27:11PM +0200, Bastien Nocera wrote:
> On Tue, 2022-08-09 at 18:33 +0200, Greg Kroah-Hartman wrote:
> > On Tue, Aug 09, 2022 at 04:31:04PM +0200, Bastien Nocera wrote:
> > > On Tue, 2022-08-09 at 12:38 +0200, Greg Kroah-Hartman wrote:
> > > > Now if you really really want to disable a device from under a
> > > > user,
> > > > without the file handle present, you can do that today, as root,
> > > > by
> > > > doing the 'unbind' hack through userspace and sysfs.  It's so
> > > > common
> > > > that this seems to be how virtual device managers handle virtual
> > > > machines, so it should be well tested by now.
> > > 
> > > The only thing I know that works that way is usbip, and it requires
> > > unbinding each of the interfaces:
> > > 
> > > https://sourceforge.net/p/usbip/git-windows/ci/master/tree/trunk/userspace/src/bind-driver.c#l157
> > 
> > virtio devices also use the api from what I recall.
> 
> I can't find any code that would reference
> /sys/bus/usb/drivers/usbfs/unbind or /sys/bus/usb/drivers/usbfs wrt
> virtio. Where's the host side code for that?

I mean the virtio code uses bind/unbind for it's devices, nothing to do
with USB other than the userspace interface involved.

thanks,

greg k-h