Re: [edk2-devel] Non-obvious network boot stack issues in OVMF after 4c4ceb2 (NetworkPkg: SECURITY PATCH CVE-2023-45237)

["Mike Beaton" <mjsbeaton@gmail.com>]

On Wed, 21 Aug 2024 at 11:38, Gerd Hoffmann <kraxel@redhat.com> wrote:
>
> On Sat, Aug 10, 2024 at 10:08:20AM GMT, Mike Beaton wrote:
> > The network boot stack fails to load in OVMF after
> > 4c4ceb2ceb80c42fd5545b2a4bd80321f07f4345 (NetworkPkg: SECURITY PATCH
> > CVE-2023-45237): https://bugzilla.tianocore.org/show_bug.cgi?id=4827
> >
> > I have now understood that this is because the network stack drivers
> > have been updated to require an instance of gEfiRngProtocolGuid, so
> > OVMF now requires the `-device virtio-rng-pci` qemu option in order
> > for the network stack to load (this flag is required in order for
> > VirtioRngDxe to be able to provide the required protocol).
>
> FYI: With the upcoming 2024-08 stable tag this will be relaxed,
> a CPU with rdrand instruction support will work too as source
> for random numbers.
>
> See https://github.com/tianocore/edk2/pull/5714 for details.
>
> > 1. This is rather non-obvious - previously, the user set the
> > compilation options for the network stack, and the network stack
> > started. Ideally, perhaps, this would be fixed by adding some
> > documentation somewhere easily found, but I am not sure where. (By the
> > way, we don't get any helpful asserts which would lead us in the right
> > direction; the depex is never satisfied, so the network stack drivers
> > just never load.)
>
> Yep.  When it comes to diagnostics there is clearly room for
> improvement.
>
> > 2. I also spotted that OvmfXen has neither RngDxe nor VirtioRngDxe - I
> > have never used OvmfXen, so I am not sure about this but (since these
> > seem to be the only two drivers which produce gEfiRngProtocolGuid) at
> > least at first glance it looks as if OvmfXen won't have any RNG for
> > the network stack now, so that it's network stack would not start?
>
> There is a patch for that too in master branch, so upcoming 2024-08
> should be fine here.
>
> It has been somewhat bumpy road due to the last minute merge of the
> fixes so some fallout has been fixed only after the 2024-05 stable tag.
>
> HTH & take care,
>   Gerd

Thank you for these clarifications, that is helpful. Appreciated!

Mike


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