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audk/MdeModulePkg/Universal/Variable/RuntimeDxe/TcgMorLockSmm.c

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/** @file
TCG MOR (Memory Overwrite Request) Lock Control support (SMM version).
This module initilizes MemoryOverwriteRequestControlLock variable.
This module adds Variable Hook and check MemoryOverwriteRequestControlLock.
Copyright (c) 2016 - 2017, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
#include <PiDxe.h>
#include <Guid/MemoryOverwriteControl.h>
#include <IndustryStandard/MemoryOverwriteRequestControlLock.h>
#include <Library/DebugLib.h>
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include "Variable.h"
typedef struct {
CHAR16 *VariableName;
EFI_GUID *VendorGuid;
} VARIABLE_TYPE;
VARIABLE_TYPE mMorVariableType[] = {
{MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME, &gEfiMemoryOverwriteControlDataGuid},
{MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME, &gEfiMemoryOverwriteRequestControlLockGuid},
};
BOOLEAN mMorPassThru = FALSE;
#define MOR_LOCK_DATA_UNLOCKED 0x0
#define MOR_LOCK_DATA_LOCKED_WITHOUT_KEY 0x1
#define MOR_LOCK_DATA_LOCKED_WITH_KEY 0x2
#define MOR_LOCK_V1_SIZE 1
#define MOR_LOCK_V2_KEY_SIZE 8
typedef enum {
MorLockStateUnlocked = 0,
MorLockStateLocked = 1,
} MOR_LOCK_STATE;
BOOLEAN mMorLockInitializationRequired = FALSE;
UINT8 mMorLockKey[MOR_LOCK_V2_KEY_SIZE];
BOOLEAN mMorLockKeyEmpty = TRUE;
BOOLEAN mMorLockPassThru = FALSE;
MOR_LOCK_STATE mMorLockState = MorLockStateUnlocked;
/**
Returns if this is MOR related variable.
@param VariableName the name of the vendor's variable, it's a Null-Terminated Unicode String
@param VendorGuid Unify identifier for vendor.
@retval TRUE The variable is MOR related.
@retval FALSE The variable is NOT MOR related.
**/
BOOLEAN
IsAnyMorVariable (
IN CHAR16 *VariableName,
IN EFI_GUID *VendorGuid
)
{
UINTN Index;
for (Index = 0; Index < sizeof(mMorVariableType)/sizeof(mMorVariableType[0]); Index++) {
if ((StrCmp (VariableName, mMorVariableType[Index].VariableName) == 0) &&
(CompareGuid (VendorGuid, mMorVariableType[Index].VendorGuid))) {
return TRUE;
}
}
return FALSE;
}
/**
Returns if this is MOR lock variable.
@param VariableName the name of the vendor's variable, it's a Null-Terminated Unicode String
@param VendorGuid Unify identifier for vendor.
@retval TRUE The variable is MOR lock variable.
@retval FALSE The variable is NOT MOR lock variable.
**/
BOOLEAN
IsMorLockVariable (
IN CHAR16 *VariableName,
IN EFI_GUID *VendorGuid
)
{
if ((StrCmp (VariableName, MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME) == 0) &&
(CompareGuid (VendorGuid, &gEfiMemoryOverwriteRequestControlLockGuid))) {
return TRUE;
}
return FALSE;
}
/**
Set MOR lock variable.
@param Data MOR Lock variable data.
@retval EFI_SUCCESS The firmware has successfully stored the variable and its data as
defined by the Attributes.
@retval EFI_INVALID_PARAMETER An invalid combination of attribute bits was supplied, or the
DataSize exceeds the maximum allowed.
@retval EFI_INVALID_PARAMETER VariableName is an empty Unicode string.
@retval EFI_OUT_OF_RESOURCES Not enough storage is available to hold the variable and its data.
@retval EFI_DEVICE_ERROR The variable could not be saved due to a hardware failure.
@retval EFI_WRITE_PROTECTED The variable in question is read-only.
@retval EFI_WRITE_PROTECTED The variable in question cannot be deleted.
@retval EFI_SECURITY_VIOLATION The variable could not be written due to EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS
set but the AuthInfo does NOT pass the validation check carried
out by the firmware.
@retval EFI_NOT_FOUND The variable trying to be updated or deleted was not found.
**/
EFI_STATUS
SetMorLockVariable (
IN UINT8 Data
)
{
EFI_STATUS Status;
mMorLockPassThru = TRUE;
Status = VariableServiceSetVariable (
MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME,
&gEfiMemoryOverwriteRequestControlLockGuid,
EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS,
sizeof(Data),
&Data
);
mMorLockPassThru = FALSE;
return Status;
}
/**
This service is an MorLock checker handler for the SetVariable().
@param VariableName the name of the vendor's variable, as a
Null-Terminated Unicode String
@param VendorGuid Unify identifier for vendor.
@param Attributes Point to memory location to return the attributes of variable. If the point
is NULL, the parameter would be ignored.
@param DataSize The size in bytes of Data-Buffer.
@param Data Point to the content of the variable.
@retval EFI_SUCCESS The MorLock check pass, and Variable driver can store the variable data.
@retval EFI_INVALID_PARAMETER The MorLock data or data size or attributes is not allowed.
@retval EFI_ACCESS_DENIED The MorLock is locked.
@retval EFI_WRITE_PROTECTED The MorLock deletion is not allowed.
@retval EFI_ALREADY_STARTED The MorLock variable is handled inside this function.
Variable driver can just return EFI_SUCCESS.
**/
EFI_STATUS
SetVariableCheckHandlerMorLock (
IN CHAR16 *VariableName,
IN EFI_GUID *VendorGuid,
IN UINT32 Attributes,
IN UINTN DataSize,
IN VOID *Data
)
{
EFI_STATUS Status;
//
// Basic Check
//
if (Attributes == 0 || DataSize == 0 || Data == NULL) {
//
// Permit deletion for passthru request, deny it otherwise.
//
return mMorLockPassThru ? EFI_SUCCESS : EFI_WRITE_PROTECTED;
}
if ((Attributes != (EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS)) ||
((DataSize != MOR_LOCK_V1_SIZE) && (DataSize != MOR_LOCK_V2_KEY_SIZE))) {
return EFI_INVALID_PARAMETER;
}
//
// Do not check if the request is passthru.
//
if (mMorLockPassThru) {
return EFI_SUCCESS;
}
if (mMorLockState == MorLockStateUnlocked) {
//
// In Unlocked State
//
if (DataSize == MOR_LOCK_V1_SIZE) {
//
// V1 - lock permanently
//
if (*(UINT8 *)Data == MOR_LOCK_DATA_UNLOCKED) {
//
// Unlock
//
Status = SetMorLockVariable (MOR_LOCK_DATA_UNLOCKED);
if (!EFI_ERROR (Status)) {
//
// return EFI_ALREADY_STARTED to skip variable set.
//
return EFI_ALREADY_STARTED;
} else {
//
// SetVar fail
//
return Status;
}
} else if (*(UINT8 *)Data == MOR_LOCK_DATA_LOCKED_WITHOUT_KEY) {
//
// Lock without key
//
Status = SetMorLockVariable (MOR_LOCK_DATA_LOCKED_WITHOUT_KEY);
if (!EFI_ERROR (Status)) {
//
// Lock success
//
mMorLockState = MorLockStateLocked;
//
// return EFI_ALREADY_STARTED to skip variable set.
//
return EFI_ALREADY_STARTED;
} else {
//
// SetVar fail
//
return Status;
}
} else {
return EFI_INVALID_PARAMETER;
}
} else if (DataSize == MOR_LOCK_V2_KEY_SIZE) {
//
// V2 lock and provision the key
//
//
// Need set here because the data value on flash is different
//
Status = SetMorLockVariable (MOR_LOCK_DATA_LOCKED_WITH_KEY);
if (EFI_ERROR(Status)) {
//
// SetVar fail, do not provision the key
//
return Status;
} else {
//
// Lock success, provision the key
//
mMorLockKeyEmpty = FALSE;
CopyMem (mMorLockKey, Data, MOR_LOCK_V2_KEY_SIZE);
mMorLockState = MorLockStateLocked;
//
// return EFI_ALREADY_STARTED to skip variable set.
//
return EFI_ALREADY_STARTED;
}
} else {
ASSERT (FALSE);
return EFI_OUT_OF_RESOURCES;
}
} else {
//
// In Locked State
//
if (mMorLockKeyEmpty || (DataSize != MOR_LOCK_V2_KEY_SIZE)) {
return EFI_ACCESS_DENIED;
}
if ((CompareMem (Data, mMorLockKey, MOR_LOCK_V2_KEY_SIZE) == 0)) {
//
// Key match - unlock
//
//
// Need set here because the data value on flash is different
//
Status = SetMorLockVariable (MOR_LOCK_DATA_UNLOCKED);
if (EFI_ERROR (Status)) {
//
// SetVar fail
//
return Status;
} else {
//
// Unlock Success
//
mMorLockState = MorLockStateUnlocked;
mMorLockKeyEmpty = TRUE;
ZeroMem (mMorLockKey, sizeof(mMorLockKey));
//
// return EFI_ALREADY_STARTED to skip variable set.
//
return EFI_ALREADY_STARTED;
}
} else {
//
// Key mismatch - Prevent Dictionary Attack
//
mMorLockState = MorLockStateLocked;
mMorLockKeyEmpty = TRUE;
ZeroMem (mMorLockKey, sizeof(mMorLockKey));
return EFI_ACCESS_DENIED;
}
}
}
/**
This service is an MOR/MorLock checker handler for the SetVariable().
@param[in] VariableName the name of the vendor's variable, as a
Null-Terminated Unicode String
@param[in] VendorGuid Unify identifier for vendor.
@param[in] Attributes Attributes bitmask to set for the variable.
@param[in] DataSize The size in bytes of Data-Buffer.
@param[in] Data Point to the content of the variable.
@retval EFI_SUCCESS The MOR/MorLock check pass, and Variable
driver can store the variable data.
@retval EFI_INVALID_PARAMETER The MOR/MorLock data or data size or
attributes is not allowed for MOR variable.
@retval EFI_ACCESS_DENIED The MOR/MorLock is locked.
@retval EFI_ALREADY_STARTED The MorLock variable is handled inside this
function. Variable driver can just return
EFI_SUCCESS.
**/
EFI_STATUS
SetVariableCheckHandlerMor (
IN CHAR16 *VariableName,
IN EFI_GUID *VendorGuid,
IN UINT32 Attributes,
IN UINTN DataSize,
IN VOID *Data
)
{
//
// do not handle non-MOR variable
//
if (!IsAnyMorVariable (VariableName, VendorGuid)) {
return EFI_SUCCESS;
}
//
// MorLock variable
//
if (IsMorLockVariable (VariableName, VendorGuid)) {
return SetVariableCheckHandlerMorLock (
VariableName,
VendorGuid,
Attributes,
DataSize,
Data
);
}
//
// Mor Variable
//
//
// Permit deletion for passthru request.
//
if (((Attributes == 0) || (DataSize == 0)) && mMorPassThru) {
return EFI_SUCCESS;
}
//
// Basic Check
//
if ((Attributes != (EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS)) ||
(DataSize != sizeof(UINT8)) ||
(Data == NULL)) {
return EFI_INVALID_PARAMETER;
}
if (mMorLockState == MorLockStateLocked) {
//
// If lock, deny access
//
return EFI_ACCESS_DENIED;
}
//
// grant access
//
return EFI_SUCCESS;
}
/**
Initialization for MOR Control Lock.
@retval EFI_SUCCESS MorLock initialization success.
@return Others Some error occurs.
**/
EFI_STATUS
MorLockInit (
VOID
)
{
mMorLockInitializationRequired = TRUE;
return EFI_SUCCESS;
}
/**
Delayed initialization for MOR Control Lock at EndOfDxe.
This function performs any operations queued by MorLockInit().
**/
VOID
MorLockInitAtEndOfDxe (
VOID
)
{
UINTN MorSize;
EFI_STATUS MorStatus;
EFI_STATUS TcgStatus;
VOID *TcgInterface;
if (!mMorLockInitializationRequired) {
//
// The EFI_SMM_FAULT_TOLERANT_WRITE_PROTOCOL has never been installed, thus
// the variable write service is unavailable. This should never happen.
//
ASSERT (FALSE);
return;
}
//
// Check if the MOR variable exists.
//
MorSize = 0;
MorStatus = VariableServiceGetVariable (
MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME,
&gEfiMemoryOverwriteControlDataGuid,
NULL, // Attributes
&MorSize,
NULL // Data
);
//
// We provided a zero-sized buffer, so the above call can never succeed.
//
ASSERT (EFI_ERROR (MorStatus));
if (MorStatus == EFI_BUFFER_TOO_SMALL) {
//
// The MOR variable exists.
//
// Some OSes don't follow the TCG's Platform Reset Attack Mitigation spec
// in that the OS should never create the MOR variable, only read and write
// it -- these OSes (unintentionally) create MOR if the platform firmware
// does not produce it. Whether this is the case (from the last OS boot)
// can be deduced from the absence of the TCG / TCG2 protocols, as edk2's
// MOR implementation depends on (one of) those protocols.
//
TcgStatus = gBS->LocateProtocol (
&gEfiTcgProtocolGuid,
NULL, // Registration
&TcgInterface
);
if (EFI_ERROR (TcgStatus)) {
TcgStatus = gBS->LocateProtocol (
&gEfiTcg2ProtocolGuid,
NULL, // Registration
&TcgInterface
);
}
if (!EFI_ERROR (TcgStatus)) {
//
// The MOR variable originates from the platform firmware; set the MOR
// Control Lock variable to report the locking capability to the OS.
//
SetMorLockVariable (0);
return;
}
//
// The MOR variable's origin is inexplicable; delete it.
//
DEBUG ((
DEBUG_WARN,
"%a: deleting unexpected / unsupported variable %g:%s\n",
__FUNCTION__,
&gEfiMemoryOverwriteControlDataGuid,
MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME
));
mMorPassThru = TRUE;
VariableServiceSetVariable (
MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME,
&gEfiMemoryOverwriteControlDataGuid,
0, // Attributes
0, // DataSize
NULL // Data
);
mMorPassThru = FALSE;
}
//
// The MOR variable is absent; the platform firmware does not support it.
// Lock the variable so that no other module may create it.
//
VariableLockRequestToLock (
NULL, // This
MEMORY_OVERWRITE_REQUEST_VARIABLE_NAME,
&gEfiMemoryOverwriteControlDataGuid
);
//
// Delete the MOR Control Lock variable too (should it exists for some
// reason) and prevent other modules from creating it.
//
mMorLockPassThru = TRUE;
VariableServiceSetVariable (
MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME,
&gEfiMemoryOverwriteRequestControlLockGuid,
0, // Attributes
0, // DataSize
NULL // Data
);
mMorLockPassThru = FALSE;
VariableLockRequestToLock (
NULL, // This
MEMORY_OVERWRITE_REQUEST_CONTROL_LOCK_NAME,
&gEfiMemoryOverwriteRequestControlLockGuid
);
}
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