dae9441ee6
- edk2-OvmfPkg-EmuVariableFvbRuntimeDxe-fix-ValidateFvHeade.patch [RHEL-220548] - Resolves: RHEL-220548 ([RHEL 10.3] TDX Secure Boot Setup Mode with OVMF.inteltdx.secboot.fd)
105 lines
4.0 KiB
Diff
105 lines
4.0 KiB
Diff
From 731f7856dd9b8fe807a3b9c60f1888f8f114ba0c Mon Sep 17 00:00:00 2001
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From: Gerd Hoffmann <kraxel@redhat.com>
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Date: Thu, 30 Jul 2026 10:44:31 +0200
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Subject: [PATCH] OvmfPkg/EmuVariableFvbRuntimeDxe: fix ValidateFvHeader in tdx
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mode.
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RH-Author: Gerd Hoffmann <kraxel@redhat.com>
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RH-MergeRequest: 115: OvmfPkg/EmuVariableFvbRuntimeDxe: fix ValidateFvHeader in tdx mode.
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RH-Jira: RHEL-220548
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RH-Acked-by: Luigi Leonardi <None>
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RH-Commit: [1/1] df1ee44a2c9af76f327a9f6bbd7f8a0ce67f1fac (kraxel.rh/centos-src-edk2)
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In TDX mode MmioRead* functions can not access memory, so avoid that.
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See added source code comments for details.
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Fixes: 0917ddad2529 ("OvmfPkg/EmuVariableFvbRuntimeDxe: avoid accessing varstore header with cmp")
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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Resolves: https://redhat.atlassian.net/browse/RHEL-220548
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---
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OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.c | 41 +++++++++++++++++++++---
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OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.inf | 1 +
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2 files changed, 38 insertions(+), 4 deletions(-)
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diff --git a/OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.c b/OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.c
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index 66e3929ec81..12b7fae2a1e 100644
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--- a/OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.c
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+++ b/OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.c
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@@ -8,6 +8,9 @@
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**/
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#include "PiDxe.h"
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+
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+#include <ConfidentialComputingGuestAttr.h>
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+
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#include <Guid/EventGroup.h>
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#include <Guid/SystemNvDataGuid.h>
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#include <Guid/VariableFormat.h>
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@@ -567,16 +570,46 @@ ValidateFvHeader (
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)
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{
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UINT16 Checksum;
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+ UINT8 Revision;
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+ UINT32 Signature;
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+ UINT64 FvLength;
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+ UINT16 HeaderLength;
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+
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+ if (CC_GUEST_IS_TDX (PcdGet64 (PcdConfidentialComputingGuestAttr))) {
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+ /*
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+ * When in tdx mode the varstore must be in ram not pflash, so there are no
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+ * mmio reads/writes needed. Also in tdx mode BaseIoLibIntrinsic will
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+ * translate the mmio access into TDVMCALL_MMIO calls instead of mov
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+ * instructions, so memory access with MmioRead* functions does not work.
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+ */
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+ Revision = FwVolHeader->Revision;
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+ Signature = FwVolHeader->Signature;
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+ FvLength = FwVolHeader->FvLength;
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+ HeaderLength = FwVolHeader->HeaderLength;
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+ } else {
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+ /*
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+ * In sev mode with varstore in pflash we must use MmioRead* functions so to
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+ * make sure the mov instruction used to access pflash/memory is supported
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+ * by the #VC handler instruction emulator.
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+ *
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+ * Note: Only sev + sev-es need proper pflash handling, sev-snp is like tdx
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+ * incompatible with pflash emulation.
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+ */
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+ Revision = MmioRead8 ((UINTN)(&FwVolHeader->Revision));
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+ Signature = MmioRead32 ((UINTN)(&FwVolHeader->Signature));
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+ FvLength = MmioRead64 ((UINTN)(&FwVolHeader->FvLength));
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+ HeaderLength = MmioRead16 ((UINTN)(&FwVolHeader->HeaderLength));
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+ }
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//
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// Verify the header revision, header signature, length
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// Length of FvBlock cannot be 2**64-1
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// HeaderLength cannot be an odd number
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//
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- if ((MmioRead8 ((UINTN)(&FwVolHeader->Revision)) != EFI_FVH_REVISION) ||
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- (MmioRead32 ((UINTN)(&FwVolHeader->Signature)) != EFI_FVH_SIGNATURE) ||
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- (MmioRead64 ((UINTN)(&FwVolHeader->FvLength)) != EMU_FVB_SIZE) ||
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- (MmioRead16 ((UINTN)(&FwVolHeader->HeaderLength)) != EMU_FV_HEADER_LENGTH)
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+ if ((Revision != EFI_FVH_REVISION) ||
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+ (Signature != EFI_FVH_SIGNATURE) ||
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+ (FvLength != EMU_FVB_SIZE) ||
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+ (HeaderLength != EMU_FV_HEADER_LENGTH)
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)
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{
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DEBUG ((DEBUG_INFO, "EMU Variable FVB: Basic FV headers were invalid\n"));
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diff --git a/OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.inf b/OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.inf
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index 396e6028b40..da1da9e0bd5 100644
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--- a/OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.inf
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+++ b/OvmfPkg/EmuVariableFvbRuntimeDxe/Fvb.inf
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@@ -63,6 +63,7 @@
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gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwWorkingBase64
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gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwSpareBase64
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gEfiMdeModulePkgTokenSpaceGuid.PcdEmuVariableNvStoreReserved
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+ gEfiMdePkgTokenSpaceGuid.PcdConfidentialComputingGuestAttr
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[Depex]
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TRUE
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--
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2.52.0
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