Re: [RFC PATCH 0/4] RFC: increased memory protection

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 23 February 2017 at 11:45, Yao, Jiewen <jiewen.yao@intel.com> wrote:
> Sounds great.
>
> I look forward to your V2.
>

Hello Jiewen,

What I am currently struggling with is the fact that we don't use the
GCD RO/XP permissions at all. This means that
RefreshGcdMemoryAttributes () (or SyncCacheConfig() on ARM) will
remove non-exec attributes if we add them in the CPU arch protocol
installation notifier callback.

So there are two approaches imo:
- introduce a way to call into the DXE core to mark all non-code
regions non-exec after RefreshGcdMemoryAttributes () has been called,
or
- add the RO/XP attributes to the GCD memory space map, and enable
them in the attributes.

Option #2 will require a change to CoreAddRange to prevent those RO/XP
attributes to leak into the UEFI memory map, because that results in
all regions have to RO/XP attributes set by default, which is
obviously not what we want.

Any thoughts?

Thanks,
Ard.