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UefiCpuPkg/PiSmmCpuDxeSmm: Use SMM Interrupt Shadow Stack

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When CET shadow stack feature is enabled, it needs to use IST for the
 exceptions, and uses interrupt shadow stack for the stack switch.
Shadow stack should be 32 bytes aligned.
Check IST field, when clear shadow stack token busy bit when using retf.

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3728

Signed-off-by: Sheng Wei <w.sheng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Rahul Kumar <rahul1.kumar@intel.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>
This commit is contained in:
Sheng, W
2021-11-12 09:40:28 +08:00
committed by mergify[bot]
parent 466ebdd2e0
commit 455b0347a7
5 changed files with 157 additions and 77 deletions
Download Patch File Download Diff File Expand all files Collapse all files

81
UefiCpuPkg/PiSmmCpuDxeSmm/X64/SmmFuncsArch.c
View File

@@ -24,24 +24,24 @@ UINT32 mCetInterruptSspTable;
UINTN mSmmInterruptSspTables;
/**
Initialize IDT for SMM Stack Guard.
Initialize IDT IST Field.
@param[in] ExceptionType Exception type.
@param[in] Ist IST value.
**/
VOID
EFIAPI
InitializeIDTSmmStackGuard (
VOID
InitializeIdtIst (
IN EFI_EXCEPTION_TYPE ExceptionType,
IN UINT8 Ist
)
{
IA32_IDT_GATE_DESCRIPTOR *IdtGate;
//
// If SMM Stack Guard feature is enabled, set the IST field of
// the interrupt gate for Page Fault Exception to be 1
//
IdtGate = (IA32_IDT_GATE_DESCRIPTOR *)gcSmiIdtr.Base;
IdtGate += EXCEPT_IA32_PAGE_FAULT;
IdtGate->Bits.Reserved_0 = 1;
IdtGate += ExceptionType;
IdtGate->Bits.Reserved_0 = Ist;
}
/**
@@ -89,7 +89,7 @@ InitGdt (
GdtDescriptor->Bits.BaseMid = (UINT8)((UINTN)TssBase >> 16);
GdtDescriptor->Bits.BaseHigh = (UINT8)((UINTN)TssBase >> 24);
if (FeaturePcdGet (PcdCpuSmmStackGuard)) {
if ((FeaturePcdGet (PcdCpuSmmStackGuard)) || ((PcdGet32 (PcdControlFlowEnforcementPropertyMask) != 0) && mCetSupported)) {
//
// Setup top of known good stack as IST1 for each processor.
//
@@ -177,8 +177,16 @@ InitShadowStack (
if ((PcdGet32 (PcdControlFlowEnforcementPropertyMask) != 0) && mCetSupported) {
SmmShadowStackSize = EFI_PAGES_TO_SIZE (EFI_SIZE_TO_PAGES (PcdGet32 (PcdCpuSmmShadowStackSize)));
//
// Add 1 page as known good shadow stack
//
SmmShadowStackSize += EFI_PAGES_TO_SIZE (1);
if (FeaturePcdGet (PcdCpuSmmStackGuard)) {
SmmShadowStackSize += EFI_PAGES_TO_SIZE (2);
//
// Add one guard page between Known Good Shadow Stack and SMM Shadow Stack.
//
SmmShadowStackSize += EFI_PAGES_TO_SIZE (1);
}
mCetPl0Ssp = (UINT32)((UINTN)ShadowStack + SmmShadowStackSize - sizeof(UINT64));
PatchInstructionX86 (mPatchCetPl0Ssp, mCetPl0Ssp, 4);
@@ -186,33 +194,32 @@ InitShadowStack (
DEBUG ((DEBUG_INFO, "ShadowStack - 0x%x\n", ShadowStack));
DEBUG ((DEBUG_INFO, " SmmShadowStackSize - 0x%x\n", SmmShadowStackSize));
if (FeaturePcdGet (PcdCpuSmmStackGuard)) {
if (mSmmInterruptSspTables == 0) {
mSmmInterruptSspTables = (UINTN)AllocateZeroPool(sizeof(UINT64) * 8 * gSmmCpuPrivate->SmmCoreEntryContext.NumberOfCpus);
ASSERT (mSmmInterruptSspTables != 0);
DEBUG ((DEBUG_INFO, "mSmmInterruptSspTables - 0x%x\n", mSmmInterruptSspTables));
}
//
// The highest address on the stack (0xFF8) is a save-previous-ssp token pointing to a location that is 40 bytes away - 0xFD0.
// The supervisor shadow stack token is just above it at address 0xFF0. This is where the interrupt SSP table points.
// So when an interrupt of exception occurs, we can use SAVESSP/RESTORESSP/CLEARSSBUSY for the supervisor shadow stack,
// due to the reason the RETF in SMM exception handler cannot clear the BUSY flag with same CPL.
// (only IRET or RETF with different CPL can clear BUSY flag)
// Please refer to UefiCpuPkg/Library/CpuExceptionHandlerLib/X64 for the full stack frame at runtime.
//
InterruptSsp = (UINT32)((UINTN)ShadowStack + EFI_PAGES_TO_SIZE(1) - sizeof(UINT64));
*(UINT64 *)(UINTN)InterruptSsp = (InterruptSsp - sizeof(UINT64) * 4) | 0x2;
mCetInterruptSsp = InterruptSsp - sizeof(UINT64);
mCetInterruptSspTable = (UINT32)(UINTN)(mSmmInterruptSspTables + sizeof(UINT64) * 8 * CpuIndex);
InterruptSspTable = (UINT64 *)(UINTN)mCetInterruptSspTable;
InterruptSspTable[1] = mCetInterruptSsp;
PatchInstructionX86 (mPatchCetInterruptSsp, mCetInterruptSsp, 4);
PatchInstructionX86 (mPatchCetInterruptSspTable, mCetInterruptSspTable, 4);
DEBUG ((DEBUG_INFO, "mCetInterruptSsp - 0x%x\n", mCetInterruptSsp));
DEBUG ((DEBUG_INFO, "mCetInterruptSspTable - 0x%x\n", mCetInterruptSspTable));
if (mSmmInterruptSspTables == 0) {
mSmmInterruptSspTables = (UINTN)AllocateZeroPool(sizeof(UINT64) * 8 * gSmmCpuPrivate->SmmCoreEntryContext.NumberOfCpus);
ASSERT (mSmmInterruptSspTables != 0);
DEBUG ((DEBUG_INFO, "mSmmInterruptSspTables - 0x%x\n", mSmmInterruptSspTables));
}
//
// The highest address on the stack (0xFE0) is a save-previous-ssp token pointing to a location that is 40 bytes away - 0xFB8.
// The supervisor shadow stack token is just above it at address 0xFD8. This is where the interrupt SSP table points.
// So when an interrupt of exception occurs, we can use SAVESSP/RESTORESSP/CLEARSSBUSY for the supervisor shadow stack,
// due to the reason the RETF in SMM exception handler cannot clear the BUSY flag with same CPL.
// (only IRET or RETF with different CPL can clear BUSY flag)
// Please refer to UefiCpuPkg/Library/CpuExceptionHandlerLib/X64 for the full stack frame at runtime.
// According to SDM (ver. 075 June 2021), shadow stack should be 32 bytes aligned.
//
InterruptSsp = (UINT32)(((UINTN)ShadowStack + EFI_PAGES_TO_SIZE(1) - (sizeof(UINT64) * 4)) & ~0x1f);
*(UINT64 *)(UINTN)InterruptSsp = (InterruptSsp - sizeof(UINT64) * 4) | 0x2;
mCetInterruptSsp = InterruptSsp - sizeof(UINT64);
mCetInterruptSspTable = (UINT32)(UINTN)(mSmmInterruptSspTables + sizeof(UINT64) * 8 * CpuIndex);
InterruptSspTable = (UINT64 *)(UINTN)mCetInterruptSspTable;
InterruptSspTable[1] = mCetInterruptSsp;
PatchInstructionX86 (mPatchCetInterruptSsp, mCetInterruptSsp, 4);
PatchInstructionX86 (mPatchCetInterruptSspTable, mCetInterruptSspTable, 4);
DEBUG ((DEBUG_INFO, "mCetInterruptSsp - 0x%x\n", mCetInterruptSsp));
DEBUG ((DEBUG_INFO, "mCetInterruptSspTable - 0x%x\n", mCetInterruptSspTable));
}
}