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From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
To: "Yao, Jiewen" <jiewen.yao@intel.com>
Cc: "edk2-devel@lists.01.org" <edk2-devel@lists.01.org>,
	"afish@apple.com" <afish@apple.com>,
	 "leif.lindholm@linaro.org" <leif.lindholm@linaro.org>,
	"Kinney, Michael D" <michael.d.kinney@intel.com>,
	 "Gao, Liming" <liming.gao@intel.com>,
	"lersek@redhat.com" <lersek@redhat.com>,
	 "Tian, Feng" <feng.tian@intel.com>,
	"Zeng, Star" <star.zeng@intel.com>
Subject: Re: [RFC PATCH 0/4] RFC: increased memory protection
Date: Thu, 23 Feb 2017 11:39:16 +0000	[thread overview]
Message-ID: <CAKv+Gu_KxDi108d-r_8+dmLPYwJ3dXij7CwRK-fcBgvOwiBw1Q@mail.gmail.com> (raw)
In-Reply-To: <74D8A39837DF1E4DA445A8C0B3885C503A8F4220@shsmsx102.ccr.corp.intel.com>

On 23 February 2017 at 08:52, Yao, Jiewen <jiewen.yao@intel.com> wrote:
> HI Ard
>
> Thanks to protect more. :-)
>

Of course! This is a very important topic for me.

> We did consider the idea to remove EXEC attribute for Data page before. But
> we got compatibility issue.
>
>
>
> We documented some gaps in white paper -
>
> https://github.com/tianocore-docs/Docs/raw/master/White_Papers/A_Tour_Beyond_BIOS_Memory_Map_And_Practices_in_UEFI_BIOS_V2.pdf
>

Thanks for the link.

> I am glad that some limitation is already resolved or we have solution to
> mitigate it. But there is still some other need consideration.
>
>
>
> 1)      We observe some 3rd part code allocating data page for code. – That
> is hardest part. (OS limitation #12)
>
> We might also need consider ReservedMemory/AcpiNvs. There might be code
> there, too. (Firmware limitation #6 and #7).
>

OK

> If we want to apply the protection, we might need define a new PCD to
> disable the data protection for compatibility consideration.
>
>
>
> 2)      About DxeCore in data page. (Firmware limitation #4)
>
> I am thinking if we can fix LoadFile implementation in PeiCore.
>
>
>
> MdeModulePkg\Core\Pei\Image\Image.c:
>
> LoadAndRelocatePeCoffImage()
>
> {
>
> ImageContext.ImageAddress = (EFI_PHYSICAL_ADDRESS)(UINTN) AllocatePages
> (EFI_SIZE_TO_PAGES ((UINT32) AlignImageSize));
>
> }
>
>
>
> AllocatePages means to allocate data page.
>
> I think we should use PeiAllocatePages(EfiBootServicesCode,
> EFI_SIZE_TO_PAGES ((UINT32) AlignImageSize), &ImageContext.ImageAddress);
>
>
>
> Does that fix the problem?
>

Using PeiServicesAllocatePage() in the way that you describe does
indeed remove the problem, so I will use that instead.

> 3)      I am not worried about EBC. That can be handled separately.
>

OK


> 4)      I did not find patch 4/4 in my mail box. Maybe it is lost due to
> some unknown reason. Would you please send it again?
>

https://lists.01.org/pipermail/edk2-devel/2017-February/007685.html

I will send out a v2 shortly which, as you suggest, moves the handling
to DXE core. The only problem is that ARM's SyncCacheConfig() removes
the noexec attributes again, so I need to fix that first. Then, the
arch CPU protocol installation event can iterate over the memory map
to set the permissions according to a policy PCD

Thanks,
Ard.


  reply	other threads:[~2017-02-23 11:39 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-22 18:24 [RFC PATCH 0/4] RFC: increased memory protection Ard Biesheuvel
2017-02-22 18:24 ` [RFC PATCH 1/4] MdeModulePkg/DxeCore: allow BootServicesData->BootServicesCode conversion Ard Biesheuvel
2017-02-22 18:24 ` [RFC PATCH 2/4] MdeModulePkg/DxeCore: convert the DxeCore memory region to BootServicesCode Ard Biesheuvel
2017-02-22 18:24 ` [RFC PATCH 3/4] MdeModulePkg/DxeCore: lift non-exec permissions on loaded images Ard Biesheuvel
2017-02-22 18:24 ` [RFC PATCH 4/4] ArmPkg/CpuDxe: remap all data regions non-executable Ard Biesheuvel
2017-02-23  8:52 ` [RFC PATCH 0/4] RFC: increased memory protection Yao, Jiewen
2017-02-23 11:39   ` Ard Biesheuvel [this message]
2017-02-23 11:45     ` Yao, Jiewen
2017-02-23 19:32       ` Ard Biesheuvel
2017-02-24  2:25         ` Yao, Jiewen
2017-02-23 10:34 ` Laszlo Ersek

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