linux-hardening - Re: [PATCH v2 00/23] x86_64: Improvements at compressed kernel stage

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Message-ID: <20221121094206.GA3967@linux-l9pv.suse>
Date:   Mon, 21 Nov 2022 17:42:06 +0800
From:   joeyli <jlee@...e.com>
To:     Evgeniy Baskov <baskov@...ras.ru>
Cc:     Ard Biesheuvel <ardb@...nel.org>, Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Alexey Khoroshilov <khoroshilov@...ras.ru>,
        Peter Jones <pjones@...hat.com>, lvc-project@...uxtesting.org,
        x86@...nel.org, linux-efi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2 00/23] x86_64: Improvements at compressed kernel stage

On Sun, Nov 20, 2022 at 06:37:40PM +0300, Evgeniy Baskov wrote:
> On 2022-11-20 04:49, joeyli wrote:
> > Hi Evgeniy,
> > 
> > Thanks for your effort!
> > 
> > On Tue, Oct 25, 2022 at 05:12:38PM +0300, Evgeniy Baskov wrote:
> ...
> > 
> > Because Peter Jones point out this patchset to me, so I tried it
> > on OVMF, and I set the EfiLoaderData in DXE memory protection policy:
> > 
> > Index: edk2/MdeModulePkg/MdeModulePkg.dec
> > ===================================================================
> > --- edk2.orig/MdeModulePkg/MdeModulePkg.dec
> > +++ edk2/MdeModulePkg/MdeModulePkg.dec
> > @@ -1392,7 +1392,7 @@
> >    # e.g. 0x7BD4 can be used for all memory except Code and
> > ACPINVS/Reserved. <BR>
> >    #
> >    # @Prompt Set DXE memory protection policy.
> > -
> > gEfiMdeModulePkgTokenSpaceGuid.PcdDxeNxMemoryProtectionPolicy|0x0000000|UINT64|0x00001048^M
> > +
> > gEfiMdeModulePkgTokenSpaceGuid.PcdDxeNxMemoryProtectionPolicy|0x0000004|UINT64|0x00001048^M
> > 
> >    ## PCI Serial Device Info. It is an array of Device, Function, and
> > Power Management
> >    #  information that describes the path that contains zero or more
> > PCI to PCI bridges
> > 
> > 
> > I applied this v2 patch set on top of v6.1-rc5 kernel, and boot with a
> > shim which
> > set the PE NX-compatibility DLL Characteristic flag. I got a page
> > fault exception:
> > 
> > Loading Linux 6.1.0-rc5-default+ ...
> > Loading initial ramdisk ...
> > !!!! X64 Exception Type - 0E(#PF - Page-Fault)  CPU Apic ID - 00000000
> > !!!!
> > ExceptionData - 0000000000000011  I:1 R:0 U:0 W:0 P:1 PK:0 SS:0 SGX:0
> > RIP  - 0000000076A3C390, CS  - 0000000000000038, RFLAGS -
> > 0000000000210202
> > RAX  - 000000007D8CCDF8, RCX - 0000000076A3C390, RDX - 000000007DE86000
> > RBX  - 0000000076A3C000, RSP - 000000007FF0D2C8, RBP - 000000007DE86000
> > RSI  - 000000007F9EE018, RDI - 000000007DFD1C18
> > R8   - 0000000076A3C000, R9  - 0000000000000190, R10 - 000000007FF1D658
> > R11  - 0000000000000004, R12 - 0000000000000190, R13 - 000000007D8CCE00
> > R14  - 000000007D8C76B4, R15 - 000000007BF0CBD5
> > DS   - 0000000000000030, ES  - 0000000000000030, FS  - 0000000000000030
> > GS   - 0000000000000030, SS  - 0000000000000030
> > CR0  - 0000000080010033, CR2 - 0000000076A3C390, CR3 - 000000007FC01000
> > CR4  - 0000000000000668, CR8 - 0000000000000000
> > DR0  - 0000000000000000, DR1 - 0000000000000000, DR2 - 0000000000000000
> > DR3  - 0000000000000000, DR6 - 00000000FFFF0FF0, DR7 - 0000000000000400
> > GDTR - 000000007F9DE000 0000000000000047, LDTR - 0000000000000000
> > IDTR - 000000007F2E9018 0000000000000FFF,   TR - 0000000000000000
> > FXSAVE_STATE - 000000007FF0CF20
> > !!!! Find image based on IP(0x7BF0BAB5)
> > /mnt/working/source_code-git/edk2/Build/OvmfX64/DEBUG_GCC5/X64/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableRuntimeDxe/DEBUG/VariableRuntimeDxe.dll
> > (ImageBase=0000000000F40E7C, EntryPoint=0000000000F767B8) !!!!
> > 
> > 
> > My question is: Can I just set EfiLoaderData in DXE memory protection
> > policy
> > in EDK2/OVMF to test this patchset? Or which platform (virtual or
> > physical)
> > can we use for testing?
> > 
> > Thanks a lot!
> > Joey Lee
> 
> Hi,
> 
> Thank you for testing!
> 
> The EDK2 OVMF with adjusted PcdDxeNxMemoryProtectionPolicy
> should work with the kernel itself.
>

Thanks for your information. And yes, I have tested v6.1
kernel with this patch set success by direct booting EFI but
by firmware's EFI boot manager
 
> As far as I can see from my testing with EDK2 OVMF, this
> #PF occurred inside GRUB code before the first instruction
> of the kernel. You can try using GRUB master branch, where
> allocations are changed to use EfiLoaderCode type and with
> PcdDxeNxMemoryProtectionPolicy=0x0000004 it will still be
> executable.
>

Thanks! We will check new grub2!

Joey Lee