Re: [PATCH v2 2/2] OvmfPkg/PlatformPei: DENY_EXECUTE_ON_SECURITY_VIOLATION when SEV is active

[Laszlo Ersek <lersek@redhat.com>]

On 10/05/17 22:16, Brijesh Singh wrote:
> The following commit:
> 
> 1fea9ddb4e3f OvmfPkg: execute option ROM images regardless of Secure Boot
> 
> sets the OptionRomImageVerificationPolicy to ALWAYS_EXECUTE the expansion
> ROMs attached to the emulated PCI devices. A expansion ROM constitute
> another channel through which a cloud provider (i.e hypervisor) can
> inject a code in guest boot flow to compromise it.
> 
> When SEV is enabled, the bios code has been verified by the guest owner
> via the SEV guest launch sequence before its executed. When secure boot,
> is enabled, lets make sure that we do not allow guest bios to execute a
> code which is not signed by the guest owner.
> 
> Fixes: https://bugzilla.tianocore.org/show_bug.cgi?id=728
> Cc: Chao Zhang <chao.b.zhang@intel.com>
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Cc: Laszlo Ersek <lersek@redhat.com>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
> Changes since v1:
>  * Add Contributed-under tag
>  * Fix OvmfPkgIa32.dsc build
> 
>  OvmfPkg/OvmfPkgIa32.dsc             | 9 +++++----
>  OvmfPkg/OvmfPkgIa32X64.dsc          | 9 +++++----
>  OvmfPkg/OvmfPkgX64.dsc              | 9 +++++----
>  OvmfPkg/PlatformPei/PlatformPei.inf | 2 ++
>  OvmfPkg/PlatformPei/AmdSev.c        | 7 +++++++
>  5 files changed, 24 insertions(+), 12 deletions(-)
> 
> diff --git a/OvmfPkg/OvmfPkgIa32.dsc b/OvmfPkg/OvmfPkgIa32.dsc
> index 92e943d4a0d0..7fb557b7c9cd 100644
> --- a/OvmfPkg/OvmfPkgIa32.dsc
> +++ b/OvmfPkg/OvmfPkgIa32.dsc
> @@ -483,10 +483,6 @@ [PcdsFixedAtBuild]
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStackSize|0x4000
>  !endif
>  
> -!if $(SECURE_BOOT_ENABLE) == TRUE
> -  gEfiSecurityPkgTokenSpaceGuid.PcdOptionRomImageVerificationPolicy|0x00
> -!endif
> -
>    # IRQs 5, 9, 10, 11 are level-triggered
>    gPcAtChipsetPkgTokenSpaceGuid.Pcd8259LegacyModeEdgeLevel|0x0E20
>  
> @@ -544,6 +540,11 @@ [PcdsDynamicDefault]
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmApSyncTimeout|100000
>  !endif
>  
> +!if $(SECURE_BOOT_ENABLE) == TRUE
> +  gEfiSecurityPkgTokenSpaceGuid.PcdOptionRomImageVerificationPolicy|0x00
> +!endif
> +
> +
>  ################################################################################
>  #
>  # Components Section - list of all EDK II Modules needed by this Platform.
> diff --git a/OvmfPkg/OvmfPkgIa32X64.dsc b/OvmfPkg/OvmfPkgIa32X64.dsc
> index 7f9220ccb90a..4bcbddb95768 100644
> --- a/OvmfPkg/OvmfPkgIa32X64.dsc
> +++ b/OvmfPkg/OvmfPkgIa32X64.dsc
> @@ -489,10 +489,6 @@ [PcdsFixedAtBuild.X64]
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStackSize|0x4000
>  !endif
>  
> -!if $(SECURE_BOOT_ENABLE) == TRUE
> -  gEfiSecurityPkgTokenSpaceGuid.PcdOptionRomImageVerificationPolicy|0x00
> -!endif
> -
>    # IRQs 5, 9, 10, 11 are level-triggered
>    gPcAtChipsetPkgTokenSpaceGuid.Pcd8259LegacyModeEdgeLevel|0x0E20
>  
> @@ -552,6 +548,11 @@ [PcdsDynamicDefault]
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmApSyncTimeout|100000
>  !endif
>  
> +!if $(SECURE_BOOT_ENABLE) == TRUE
> +  gEfiSecurityPkgTokenSpaceGuid.PcdOptionRomImageVerificationPolicy|0x00
> +!endif
> +
> +
>  ################################################################################
>  #
>  # Components Section - list of all EDK II Modules needed by this Platform.
> diff --git a/OvmfPkg/OvmfPkgX64.dsc b/OvmfPkg/OvmfPkgX64.dsc
> index 36c60fc19c40..e52a3bd4db9b 100644
> --- a/OvmfPkg/OvmfPkgX64.dsc
> +++ b/OvmfPkg/OvmfPkgX64.dsc
> @@ -488,10 +488,6 @@ [PcdsFixedAtBuild]
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmStackSize|0x4000
>  !endif
>  
> -!if $(SECURE_BOOT_ENABLE) == TRUE
> -  gEfiSecurityPkgTokenSpaceGuid.PcdOptionRomImageVerificationPolicy|0x00
> -!endif
> -
>    # IRQs 5, 9, 10, 11 are level-triggered
>    gPcAtChipsetPkgTokenSpaceGuid.Pcd8259LegacyModeEdgeLevel|0x0E20
>  
> @@ -551,6 +547,11 @@ [PcdsDynamicDefault]
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuSmmApSyncTimeout|100000
>  !endif
>  
> +!if $(SECURE_BOOT_ENABLE) == TRUE
> +  gEfiSecurityPkgTokenSpaceGuid.PcdOptionRomImageVerificationPolicy|0x00
> +!endif
> +
> +
>  ################################################################################
>  #
>  # Components Section - list of all EDK II Modules needed by this Platform.
> diff --git a/OvmfPkg/PlatformPei/PlatformPei.inf b/OvmfPkg/PlatformPei/PlatformPei.inf
> index 16a8db7b0bd2..de7434d93dc0 100644
> --- a/OvmfPkg/PlatformPei/PlatformPei.inf
> +++ b/OvmfPkg/PlatformPei/PlatformPei.inf
> @@ -41,6 +41,7 @@ [Packages]
>    IntelFrameworkModulePkg/IntelFrameworkModulePkg.dec
>    MdePkg/MdePkg.dec
>    MdeModulePkg/MdeModulePkg.dec
> +  SecurityPkg/SecurityPkg.dec
>    UefiCpuPkg/UefiCpuPkg.dec
>    OvmfPkg/OvmfPkg.dec
>  
> @@ -96,6 +97,7 @@ [Pcd]
>    gEfiMdeModulePkgTokenSpaceGuid.PcdPropertiesTableEnable
>    gEfiMdeModulePkgTokenSpaceGuid.PcdAcpiS3Enable
>    gEfiMdeModulePkgTokenSpaceGuid.PcdPteMemoryEncryptionAddressOrMask
> +  gEfiSecurityPkgTokenSpaceGuid.PcdOptionRomImageVerificationPolicy
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuLocalApicBaseAddress
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuMaxLogicalProcessorNumber
>    gUefiCpuPkgTokenSpaceGuid.PcdCpuApInitTimeOutInMicroSeconds
> diff --git a/OvmfPkg/PlatformPei/AmdSev.c b/OvmfPkg/PlatformPei/AmdSev.c
> index 26f7c3fdbb13..1539e5b5cdce 100644
> --- a/OvmfPkg/PlatformPei/AmdSev.c
> +++ b/OvmfPkg/PlatformPei/AmdSev.c
> @@ -59,4 +59,11 @@ AmdSevInitialize (
>    ASSERT_RETURN_ERROR (PcdStatus);
>  
>    DEBUG ((DEBUG_INFO, "SEV is enabled (mask 0x%lx)\n", EncryptionMask));
> +
> +  //
> +  // Set Pcd to Deny the execution of option ROM when security
> +  // violation.
> +  //
> +  PcdStatus = PcdSet32S (PcdOptionRomImageVerificationPolicy, 0x4);
> +  ASSERT_RETURN_ERROR (PcdStatus);
>  }
> 

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Thanks!
Laszlo