Re: [PATCH] uio_pci_generic does not export memory resources

Michael S. Tsirkin
2012-06-10T19:16:42Z

On Sun, Jun 10, 2012 at 09:11:30PM +0200, Hans J. Koch wrote:
> On Sun, Jun 10, 2012 at 10:00:36PM +0300, Michael S. Tsirkin wrote:
> >
> > One thing I stand corrected on: assigning a PF that does DMA with VFIO
> > *might* be secure, and sometimes, maybe often, is.
> > There's just no way to make sure.
> > This is unlike uio_pci_generic where it would always be insecure.
>
> You need to be root to access a UIO device, and if you're root, you can
> compromise a system in many ways. Before UIO, people used /dev/mem for
> similar purposes, and UIO is certainly a seccurity improvement over that.
>
> But of course, UIO presents security risks. Like many other things below
> /dev, you need to know what you're doing, and who gets access to /dev/uioX.
>
> Thanks,
> Hans

Sorry I might not have explained myself clearly. uio_pci_generic would
be insecure if used with a device doing DMA. I am not speaking
about UIO in general at all.

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MST