[edk2-devel] [PATCH 00/12] SEV-ES security mitigations

[Laszlo Ersek]

Hi Tom,

On 12/15/20 21:50, Tom Lendacky wrote:
> From: Tom Lendacky <thomas.lendacky at amd.com>
> 
> This patch series provides security mitigations for SEV-ES to protect
> against some attacks identified in the paper titled "Exploiting Interfaces
> of Secure Encrypted Virtual Machines" at:
>   https://arxiv.org/pdf/2010.07094.pdf
> 
> The mitigations include:
> 
> - Validating the encryption bit position provided by the hypervisor.
>   Additionally, once validated use the validated value throughout the
>   code.
> 
> - Validating that SEV-ES has been advertised to the guest if a #VC has
>   been taken to prevent the hypervisor from pretending that SEV-ES is
>   not enabled.
> 
> - Validate that MMIO is performed to/from unencrypted memory addresses
>   to prevent the hypervisor try to inject data or expose secrets within
>   the guest.
> 
> And a change separate from the above paper:
> 
> - When checking #VC related per-vCPU values, make checks for explicit
>   values vs non-zero values so that a hypervisor can't write random data
>   to the location to alter guest processing behavior.
> 
> Also, as part of creating these mitigations:
> - MemEncryptSevLib is updated to now be available during SEC
> - #VC now supports a single nested invocation
> 
> BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3108
> 
> ---
> 
> These patches are based on commit:
> 5c3cdebf95bf ("MdePkg/include: Add DMAR SATC Table Definition")

I plan to review this series next year (and then after the VCPU
hot-unplug stuff that's already been in my review queue for a bit...)

Thanks,
Laszlo

> 
> Cc: Ard Biesheuvel <ard.biesheuvel at arm.com>
> Cc: Rebecca Cran <rebecca at bsdio.com>
> Cc: Laszlo Ersek <lersek at redhat.com>
> Cc: Julien Grall <julien at xen.org>
> Cc: Peter Grehan <grehan at freebsd.org>
> Cc: Jordan Justen <jordan.l.justen at intel.com>
> Cc: Anthony Perard <anthony.perard at citrix.com>
> Cc: Brijesh Singh <brijesh.singh at amd.com>
> 
> Tom Lendacky (12):
>   Ovmf/ResetVector: Simplify and consolidate the SEV features checks
>   OvmfPkg/Sec: Move SEV-ES SEC workarea definition to common header file
>   OvmfPkg/ResetVector: Validate the encryption bit position for
>     SEV/SEV-ES
>   OvmfPkg/ResetVector: Perform a simple SEV-ES sanity check
>   OvmfPkg/MemEncryptSevLib: Add an interface to retrieve the encryption
>     mask
>   OvmfPkg/AmdSevDxe: Clear encryption bit on PCIe MMCONFIG range
>   OvmfPkg/VmgExitLib: Check for an explicit DR7 cached value
>   OvmfPkg/MemEncryptSevLib: Make the MemEncryptSevLib available for SEC
>   OvmfPkg/MemEncryptSevLib: Address range encryption state interface
>   OvmfPkg/VmgExitLib: Support nested #VCs
>   OvmfPkg/PlatformPei: Reserve GHCB backup pages if S3 is supported
>   OvfmPkg/VmgExitLib: Validate #VC MMIO is to un-encrypted memory
> 
>  OvmfPkg/OvmfPkg.dec                           |   2 +
>  OvmfPkg/AmdSev/AmdSevX64.dsc                  |   6 +-
>  OvmfPkg/Bhyve/BhyveX64.dsc                    |   4 +-
>  OvmfPkg/OvmfPkgIa32.dsc                       |   4 +-
>  OvmfPkg/OvmfPkgIa32X64.dsc                    |   4 +-
>  OvmfPkg/OvmfPkgX64.dsc                        |   6 +-
>  OvmfPkg/OvmfXen.dsc                           |   3 +-
>  OvmfPkg/AmdSev/AmdSevX64.fdf                  |   3 +
>  OvmfPkg/OvmfPkgX64.fdf                        |   3 +
>  OvmfPkg/AmdSevDxe/AmdSevDxe.inf               |   8 +-
>  ...SevLib.inf => DxeBaseMemEncryptSevLib.inf} |  14 +-
>  .../PeiBaseMemEncryptSevLib.inf               |  57 ++
>  .../SecBaseMemEncryptSevLib.inf               |  55 +
>  OvmfPkg/Library/VmgExitLib/SecVmgExitLib.inf  |  44 +
>  OvmfPkg/Library/VmgExitLib/VmgExitLib.inf     |   6 +-
>  OvmfPkg/PlatformPei/PlatformPei.inf           |   2 +
>  OvmfPkg/Include/Library/MemEncryptSevLib.h    |  90 +-
>  .../BaseMemEncryptSevLib/X64/VirtualMemory.h  |  35 +-
>  OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.h |  53 +
>  OvmfPkg/AmdSevDxe/AmdSevDxe.c                 |  20 +-
>  OvmfPkg/Bhyve/PlatformPei/AmdSev.c            |  12 +-
>  .../DxeMemEncryptSevLibInternal.c             | 145 +++
>  .../Ia32/MemEncryptSevLib.c                   |  31 +-
>  .../MemEncryptSevLibInternal.c                |  91 +-
>  .../PeiMemEncryptSevLibInternal.c             | 159 +++
>  .../SecMemEncryptSevLibInternal.c             | 130 +++
>  .../X64/MemEncryptSevLib.c                    |  32 +-
>  .../X64/PeiDxeVirtualMemory.c                 | 893 ++++++++++++++++
>  .../X64/SecVirtualMemory.c                    | 100 ++
>  .../BaseMemEncryptSevLib/X64/VirtualMemory.c  | 954 +++---------------
>  .../VmgExitLib/PeiDxeVmgExitVcHandler.c       | 103 ++
>  .../Library/VmgExitLib/SecVmgExitVcHandler.c  | 109 ++
>  OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.c | 130 ++-
>  OvmfPkg/PlatformPei/AmdSev.c                  |  50 +-
>  OvmfPkg/PlatformPei/MemDetect.c               |   5 +
>  OvmfPkg/Sec/SecMain.c                         |   6 +-
>  OvmfPkg/XenPlatformPei/AmdSev.c               |  12 +-
>  OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm   | 116 +++
>  OvmfPkg/ResetVector/Ia32/PageTables64.asm     | 108 +-
>  OvmfPkg/ResetVector/ResetVector.nasmb         |   5 +-
>  40 files changed, 2590 insertions(+), 1020 deletions(-)
>  rename OvmfPkg/Library/BaseMemEncryptSevLib/{BaseMemEncryptSevLib.inf => DxeBaseMemEncryptSevLib.inf} (66%)
>  create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/PeiBaseMemEncryptSevLib.inf
>  create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/SecBaseMemEncryptSevLib.inf
>  create mode 100644 OvmfPkg/Library/VmgExitLib/SecVmgExitLib.inf
>  create mode 100644 OvmfPkg/Library/VmgExitLib/VmgExitVcHandler.h
>  create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/DxeMemEncryptSevLibInternal.c
>  create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/PeiMemEncryptSevLibInternal.c
>  create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/SecMemEncryptSevLibInternal.c
>  create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/X64/PeiDxeVirtualMemory.c
>  create mode 100644 OvmfPkg/Library/BaseMemEncryptSevLib/X64/SecVirtualMemory.c
>  create mode 100644 OvmfPkg/Library/VmgExitLib/PeiDxeVmgExitVcHandler.c
>  create mode 100644 OvmfPkg/Library/VmgExitLib/SecVmgExitVcHandler.c
>  create mode 100644 OvmfPkg/ResetVector/Ia32/Flat32ToFlat64.asm
> 



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