#include <Protocol/SmmVariable.h>
#include <Protocol/SmmFirmwareVolumeBlock.h>
#include <Protocol/SmmFaultTolerantWrite.h>
#include <Protocol/MmEndOfDxe.h>
#include <Protocol/SmmVarCheck.h>
#include <Library/MmServicesTableLib.h>
#include <Library/VariablePolicyLib.h>
#include <Guid/SmmVariableCommon.h>
#include "Variable.h"
#include "VariableParsing.h"
#include "VariableRuntimeCache.h"

Functions
VOID EFIAPI	SecureBootHook (IN CHAR16 VariableName, IN EFI_GUID VendorGuid)

EFI_STATUS EFIAPI	SmmVariableSetVariable (IN CHAR16 VariableName, IN EFI_GUID VendorGuid, IN UINT32 Attributes, IN UINTN DataSize, IN VOID *Data)

BOOLEAN	AtRuntime (VOID)

EFI_LOCK *	InitializeLock (IN OUT EFI_LOCK *Lock, IN EFI_TPL Priority)

VOID	AcquireLockOnlyAtBootTime (IN EFI_LOCK *Lock)

VOID	ReleaseLockOnlyAtBootTime (IN EFI_LOCK *Lock)

EFI_STATUS	GetFtwProtocol (OUT VOID **FtwProtocol)

EFI_STATUS	GetFvbByHandle (IN EFI_HANDLE FvBlockHandle, OUT EFI_FIRMWARE_VOLUME_BLOCK_PROTOCOL **FvBlock)

EFI_STATUS	GetFvbCountAndBuffer (OUT UINTN NumberHandles, OUT EFI_HANDLE *Buffer)

EFI_STATUS	SmmVariableGetStatistics (IN OUT VARIABLE_INFO_ENTRY InfoEntry, IN OUT UINTN InfoSize)

EFI_STATUS EFIAPI	SmmVariableHandler (IN EFI_HANDLE DispatchHandle, IN CONST VOID RegisterContext, IN OUT VOID CommBuffer, IN OUT UINTN *CommBufferSize)

EFI_STATUS EFIAPI	SmmEndOfDxeCallback (IN CONST EFI_GUID Protocol, IN VOID Interface, IN EFI_HANDLE Handle)

VOID	VariableWriteServiceInitializeSmm (VOID)

EFI_STATUS EFIAPI	SmmFtwNotificationEvent (IN CONST EFI_GUID Protocol, IN VOID Interface, IN EFI_HANDLE Handle)

EFI_STATUS EFIAPI	MmVariableServiceInitialize (VOID)

Variables
VARIABLE_STORE_HEADER *	mNvVariableCache

BOOLEAN	mAtRuntime = FALSE

UINT8 *	mVariableBufferPayload = NULL

UINTN	mVariableBufferPayloadSize

EFI_SMM_VARIABLE_PROTOCOL	gSmmVariable

EDKII_SMM_VAR_CHECK_PROTOCOL	mSmmVarCheck

Detailed Description

The sample implementation for SMM variable protocol. And this driver implements an SMI handler to communicate with the DXE runtime driver to provide variable services.

Caution: This module requires additional review when modified. This driver will have external input - variable data and communicate buffer in SMM mode. This external input must be validated carefully to avoid security issue like buffer overflow, integer overflow.

SmmVariableHandler() will receive untrusted input and do basic validation.

Each sub function VariableServiceGetVariable(), VariableServiceGetNextVariableName(), VariableServiceSetVariable(), VariableServiceQueryVariableInfo(), ReclaimForOS(), SmmVariableGetStatistics() should also do validation based on its own knowledge.

Copyright (c) 2010 - 2024, Intel Corporation. All rights reserved.
Copyright (c) 2018, Linaro, Ltd. All rights reserved.
SPDX-License-Identifier: BSD-2-Clause-Patent

Definition in file VariableSmm.c.

Function Documentation

◆ AcquireLockOnlyAtBootTime()

VOID AcquireLockOnlyAtBootTime ( IN EFI_LOCK * Lock )

Acquires lock only at boot time. Simply returns at runtime.

This is a temperary function that will be removed when EfiAcquireLock() in UefiLib can handle the call in UEFI Runtimer driver in RT phase. It calls EfiAcquireLock() at boot time, and simply returns at runtime.

Parameters

Lock	A pointer to the lock to acquire.

Definition at line 169 of file VariableSmm.c.

◆ AtRuntime()

BOOLEAN AtRuntime ( VOID )

Return TRUE if ExitBootServices () has been called.

Return values

TRUE	If ExitBootServices () has been called.

Definition at line 124 of file VariableSmm.c.

◆ GetFtwProtocol()

EFI_STATUS GetFtwProtocol ( OUT VOID ** FtwProtocol )

Retrieve the SMM Fault Tolerent Write protocol interface.

Parameters

[out] FtwProtocol The interface of SMM Ftw protocol

Return values

EFI_SUCCESS	The SMM FTW protocol instance was found and returned in FtwProtocol.
EFI_NOT_FOUND	The SMM FTW protocol instance was not found.
EFI_INVALID_PARAMETER	SarProtocol is NULL.

Definition at line 205 of file VariableSmm.c.

◆ GetFvbByHandle()

EFI_STATUS GetFvbByHandle	(	IN EFI_HANDLE	FvBlockHandle,
		OUT EFI_FIRMWARE_VOLUME_BLOCK_PROTOCOL **	FvBlock
	)

Retrieve the SMM FVB protocol interface by HANDLE.

Parameters

[in]	FvBlockHandle	The handle of SMM FVB protocol that provides services for reading, writing, and erasing the target block.
[out]	FvBlock	The interface of SMM FVB protocol

Return values

EFI_SUCCESS	The interface information for the specified protocol was returned.
EFI_UNSUPPORTED	The device does not support the SMM FVB protocol.
EFI_INVALID_PARAMETER	FvBlockHandle is not a valid EFI_HANDLE or FvBlock is NULL.

Definition at line 235 of file VariableSmm.c.

◆ GetFvbCountAndBuffer()

EFI_STATUS GetFvbCountAndBuffer	(	OUT UINTN *	NumberHandles,
		OUT EFI_HANDLE **	Buffer
	)

Function returns an array of handles that support the SMM FVB protocol in a buffer allocated from pool.

Parameters

[out]	NumberHandles	The number of handles returned in Buffer.
[out]	Buffer	A pointer to the buffer to return the requested array of handles that support SMM FVB protocol.

Return values

EFI_SUCCESS	The array of handles was returned in Buffer, and the number of handles in Buffer was returned in NumberHandles.
EFI_NOT_FOUND	No SMM FVB handle was found.
EFI_OUT_OF_RESOURCES	There is not enough pool memory to store the matching results.
EFI_INVALID_PARAMETER	NumberHandles is NULL or Buffer is NULL.

Definition at line 266 of file VariableSmm.c.

◆ InitializeLock()

EFI_LOCK * InitializeLock	(	IN OUT EFI_LOCK *	Lock,
		IN EFI_TPL	Priority
	)

Initializes a basic mutual exclusion lock.

This function initializes a basic mutual exclusion lock to the released state and returns the lock. Each lock provides mutual exclusion access at its task priority level. Since there is no preemption or multiprocessor support in EFI, acquiring the lock only consists of raising to the locks TPL. If Lock is NULL, then ASSERT(). If Priority is not a valid TPL value, then ASSERT().

Parameters

Lock	A pointer to the lock data structure to initialize.
Priority	EFI TPL is associated with the lock.

Returns: The lock.

Definition at line 148 of file VariableSmm.c.

◆ MmVariableServiceInitialize()

EFI_STATUS EFIAPI MmVariableServiceInitialize ( VOID )

Variable Driver main entry point. The Variable driver places the 4 EFI runtime services in the EFI System Table and installs arch protocols for variable read and write services being available. It also registers a notification function for an EVT_SIGNAL_VIRTUAL_ADDRESS_CHANGE event.

Return values

EFI_SUCCESS Variable service successfully initialized.

Register SMM variable SMI handler

Definition at line 1151 of file VariableSmm.c.

◆ ReleaseLockOnlyAtBootTime()

VOID ReleaseLockOnlyAtBootTime ( IN EFI_LOCK * Lock )

Releases lock only at boot time. Simply returns at runtime.

This is a temperary function which will be removed when EfiReleaseLock() in UefiLib can handle the call in UEFI Runtimer driver in RT phase. It calls EfiReleaseLock() at boot time and simply returns at runtime.

Parameters

Lock	A pointer to the lock to release.

Definition at line 188 of file VariableSmm.c.

◆ SecureBootHook()

VOID EFIAPI SecureBootHook	(	IN CHAR16 *	VariableName,
		IN EFI_GUID *	VendorGuid
	)

SecureBoot Hook for SetVariable.

Parameters

[in]	VariableName	Name of Variable to be found.
[in]	VendorGuid	Variable vendor GUID.

Definition at line 52 of file VariableSmm.c.

◆ SmmEndOfDxeCallback()

EFI_STATUS EFIAPI SmmEndOfDxeCallback	(	IN CONST EFI_GUID *	Protocol,
		IN VOID *	Interface,
		IN EFI_HANDLE	Handle
	)

SMM END_OF_DXE protocol notification event handler.

Parameters

Protocol	Points to the protocol's unique identifier
Interface	Points to the interface instance
Handle	The handle on which the interface was installed

Return values

EFI_SUCCESS SmmEndOfDxeCallback runs successfully

Definition at line 1012 of file VariableSmm.c.

◆ SmmFtwNotificationEvent()

EFI_STATUS EFIAPI SmmFtwNotificationEvent	(	IN CONST EFI_GUID *	Protocol,
		IN VOID *	Interface,
		IN EFI_HANDLE	Handle
	)

SMM Fault Tolerant Write protocol notification event handler.

Non-Volatile variable write may needs FTW protocol to reclaim when writting variable.

Parameters

Protocol	Points to the protocol's unique identifier
Interface	Points to the interface instance
Handle	The handle on which the interface was installed

Return values

EFI_SUCCESS	SmmEventCallback runs successfully
EFI_NOT_FOUND	The Fvb protocol for variable is not found.

Definition at line 1075 of file VariableSmm.c.

◆ SmmVariableGetStatistics()

EFI_STATUS SmmVariableGetStatistics	(	IN OUT VARIABLE_INFO_ENTRY *	InfoEntry,
		IN OUT UINTN *	InfoSize
	)

Get the variable statistics information from the information buffer pointed by gVariableInfo.

Caution: This function may be invoked at SMM runtime. InfoEntry and InfoSize are external input. Care must be taken to make sure not security issue at runtime.

Parameters

[in,out]	InfoEntry	A pointer to the buffer of variable information entry. On input, point to the variable information returned last time. if InfoEntry->VendorGuid is zero, return the first information. On output, point to the next variable information.
[in,out]	InfoSize	On input, the size of the variable information buffer. On output, the returned variable information size.

Return values

EFI_SUCCESS	The variable information is found and returned successfully.
EFI_UNSUPPORTED	No variable inoformation exists in variable driver. The PcdVariableCollectStatistics should be set TRUE to support it.
EFI_BUFFER_TOO_SMALL	The buffer is too small to hold the next variable information.
EFI_INVALID_PARAMETER	Input parameter is invalid.

Definition at line 336 of file VariableSmm.c.

◆ SmmVariableHandler()

EFI_STATUS EFIAPI SmmVariableHandler	(	IN EFI_HANDLE	DispatchHandle,
		IN CONST VOID *	RegisterContext,
		IN OUT VOID *	CommBuffer,
		IN OUT UINTN *	CommBufferSize
	)

Communication service SMI Handler entry.

This SMI handler provides services for the variable wrapper driver.

Caution: This function may receive untrusted input. This variable data and communicate buffer are external input, so this function will do basic validation. Each sub function VariableServiceGetVariable(), VariableServiceGetNextVariableName(), VariableServiceSetVariable(), VariableServiceQueryVariableInfo(), ReclaimForOS(), SmmVariableGetStatistics() should also do validation based on its own knowledge.

Parameters

[in]	DispatchHandle	The unique handle assigned to this handler by SmiHandlerRegister().
[in]	RegisterContext	Points to an optional handler context which was specified when the handler was registered.
[in,out]	CommBuffer	A pointer to a collection of data in memory that will be conveyed from a non-SMM environment into an SMM environment.
[in,out]	CommBufferSize	The size of the CommBuffer.

Return values

EFI_SUCCESS	The interrupt was handled and quiesced. No other handlers should still be called.
EFI_WARN_INTERRUPT_SOURCE_QUIESCED	The interrupt has been quiesced but other handlers should still be called.
EFI_WARN_INTERRUPT_SOURCE_PENDING	The interrupt is still pending and other handlers should still be called.
EFI_INTERRUPT_PENDING	The interrupt could not be quiesced.

Definition at line 455 of file VariableSmm.c.

◆ SmmVariableSetVariable()

EFI_STATUS EFIAPI SmmVariableSetVariable	(	IN CHAR16 *	VariableName,
		IN EFI_GUID *	VendorGuid,
		IN UINT32	Attributes,
		IN UINTN	DataSize,
		IN VOID *	Data
	)

This code sets variable in storage blocks (Volatile or Non-Volatile).

Parameters

VariableName	Name of Variable to be found.
VendorGuid	Variable vendor GUID.
Attributes	Attribute value of the variable found
DataSize	Size of Data found. If size is less than the data, this value contains the required size.
Data	Data pointer.

Returns: EFI_INVALID_PARAMETER Invalid parameter.; EFI_SUCCESS Set successfully.; EFI_OUT_OF_RESOURCES Resource not enough to set variable.; EFI_NOT_FOUND Not found.; EFI_WRITE_PROTECTED Variable is read-only.

Definition at line 80 of file VariableSmm.c.

◆ VariableWriteServiceInitializeSmm()

VOID VariableWriteServiceInitializeSmm ( VOID )

Initializes variable write service for SMM.

Definition at line 1042 of file VariableSmm.c.

Variable Documentation

◆ gSmmVariable

EFI_SMM_VARIABLE_PROTOCOL gSmmVariable

Initial value:

= {
  VariableServiceGetVariable,
  VariableServiceGetNextVariableName,
  SmmVariableSetVariable,
  VariableServiceQueryVariableInfo
}

Definition at line 105 of file VariableSmm.c.

◆ mAtRuntime

BOOLEAN mAtRuntime = FALSE

Definition at line 39 of file VariableSmm.c.

◆ mNvVariableCache

VARIABLE_STORE_HEADER* mNvVariableCache

extern

Define a memory cache that improves the search performance for a variable. For EmuNvMode == TRUE, it will be equal to NonVolatileVariableBase.

Definition at line 39 of file Variable.c.

◆ mSmmVarCheck

EDKII_SMM_VAR_CHECK_PROTOCOL mSmmVarCheck

Initial value:

= {
  VarCheckRegisterSetVariableCheckHandler,
  VarCheckVariablePropertySet,
  VarCheckVariablePropertyGet
}

Definition at line 112 of file VariableSmm.c.

◆ mVariableBufferPayload

UINT8* mVariableBufferPayload = NULL

Definition at line 40 of file VariableSmm.c.

◆ mVariableBufferPayloadSize

UINTN mVariableBufferPayloadSize

Definition at line 41 of file VariableSmm.c.

Functions

Variables

Detailed Description

Function Documentation

◆ AcquireLockOnlyAtBootTime()

◆ AtRuntime()

◆ GetFtwProtocol()

◆ GetFvbByHandle()

◆ GetFvbCountAndBuffer()

◆ InitializeLock()

◆ MmVariableServiceInitialize()

◆ ReleaseLockOnlyAtBootTime()

◆ SecureBootHook()

◆ SmmEndOfDxeCallback()

◆ SmmFtwNotificationEvent()

◆ SmmVariableGetStatistics()

◆ SmmVariableHandler()

◆ SmmVariableSetVariable()

◆ VariableWriteServiceInitializeSmm()

Variable Documentation

◆ gSmmVariable

◆ mAtRuntime

◆ mNvVariableCache

◆ mSmmVarCheck

◆ mVariableBufferPayload

◆ mVariableBufferPayloadSize