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Re: [PATCH v3 7/9] vfio: Use driver_override to avert binding to compromising drivers

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On Mon, 26 Jun 2017 10:08:55 +0100
Russell King - ARM Linux <linux@armlinux.org.uk> wrote:

> On Tue, Jun 20, 2017 at 09:48:31AM -0600, Alex Williamson wrote:
> > If a device is bound to a non-vfio, non-whitelisted driver while a
> > group is in use, then the integrity of the group is compromised and
> > will result in hitting a BUG_ON.  This code tries to avoid this case
> > by mangling driver_override to force a no-match for the driver.  The
> > driver-core will either follow-up with a DRIVER_NOT_BOUND (preferred)
> > or BOUND_DRIVER, at which point we can remove the driver_override
> > mangling.  
> 
> Rather than mangling the driver override string to prevent driver binding,
> I wonder if it would make more sense to allow the BUS_NOTIFY_BIND_DRIVER
> notifier to fail the device probe?
> 
> The driver override strings are, after all, exposed to userspace, and
> it strikes me that this kind of mangling is racy - userspace can read
> or change the override string at any time.

Indeed, that looks easier.  I sent and RFC, let's see what Greg has to
say.  Thanks,

Alex

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[PATCH v3 0/9] vfio: Fix release ordering races and use  driver_override Alex Williamson <alex.williamson@redhat.com> - 2017-06-20 17:50 +0200
  [PATCH v3 9/9] vfio: Add AMBA driver_override support Alex Williamson <alex.williamson@redhat.com> - 2017-06-20 17:50 +0200
    Re: [PATCH v3 9/9] vfio: Add AMBA driver_override support Auger Eric <eric.auger@redhat.com> - 2017-06-26 09:40 +0200
  [PATCH v3 4/9] iommu: Add driver-not-bound notification Alex Williamson <alex.williamson@redhat.com> - 2017-06-20 17:50 +0200
  [PATCH v3 6/9] vfio: Register pci, platform, amba,  and mdev bus drivers Alex Williamson <alex.williamson@redhat.com> - 2017-06-20 17:50 +0200
  [PATCH v3 3/9] vfio: New external user group/file match Alex Williamson <alex.williamson@redhat.com> - 2017-06-20 17:50 +0200
  [PATCH v3 1/9] vfio: Fix group release deadlock Alex Williamson <alex.williamson@redhat.com> - 2017-06-20 17:50 +0200
  [PATCH v3 7/9] vfio: Use driver_override to avert binding to  compromising drivers Alex Williamson <alex.williamson@redhat.com> - 2017-06-20 17:50 +0200
    Re: [PATCH v3 7/9] vfio: Use driver_override to avert binding to  compromising drivers Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-06-26 11:10 +0200
      Re: [PATCH v3 7/9] vfio: Use driver_override to avert binding to  compromising drivers Alex Williamson <alex.williamson@redhat.com> - 2017-06-26 21:40 +0200
  [PATCH v3 5/9] vfio: Create interface for vfio bus drivers to  register Alex Williamson <alex.williamson@redhat.com> - 2017-06-20 17:50 +0200
  [PATCH v3 8/9] amba: Export amba_bustype Alex Williamson <alex.williamson@redhat.com> - 2017-06-20 17:50 +0200
    Re: [PATCH v3 8/9] amba: Export amba_bustype Auger Eric <eric.auger@redhat.com> - 2017-06-26 09:40 +0200
  [PATCH v3 2/9] kvm-vfio: Decouple only when we match a group Alex Williamson <alex.williamson@redhat.com> - 2017-06-20 18:00 +0200
    Re: [PATCH v3 2/9] kvm-vfio: Decouple only when we match a group Auger Eric <eric.auger@redhat.com> - 2017-06-26 09:40 +0200
    Re: [PATCH v3 2/9] kvm-vfio: Decouple only when we match a group Paolo Bonzini <pbonzini@redhat.com> - 2017-06-28 20:00 +0200
  Re: [PATCH v3 0/9] vfio: Fix release ordering races and use  driver_override Auger Eric <eric.auger@redhat.com> - 2017-06-26 09:40 +0200

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