/
UefiVarMonitorDxe.c
255 lines (228 loc) · 6.37 KB
/
UefiVarMonitorDxe.c
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#include <Uefi.h>
#include <Guid/EventGroup.h>
#include <Library/DebugLib.h>
#include <Library/UefiBootServicesTableLib.h>
#include <Library/UefiRuntimeServicesTableLib.h>
#include <library/UefiRuntimeLib.h>
static EFI_EVENT g_SetVaMapEvent;
static EFI_GET_VARIABLE g_GetVariable;
static EFI_SET_VARIABLE g_SetVariable;
/**
* @brief Handles GetVariable runtime service calls.
*/
static
EFI_STATUS
EFIAPI
HandleGetVariable (
IN CHAR16* VariableName,
IN EFI_GUID* VendorGuid,
OUT UINT32* Attributes OPTIONAL,
IN OUT UINTN* DataSize,
OUT VOID* Data OPTIONAL
)
{
EFI_STATUS status;
UINTN effectiveDataSize;
//
// Invoke the original GetVariable service, and log this service invocation.
//
status = g_GetVariable(VariableName, VendorGuid, Attributes, DataSize, Data);
effectiveDataSize = EFI_ERROR(status) ? 0 : *DataSize;
DebugPrint(DEBUG_VERBOSE,
"G: %g Size=%08x %s: %r\n",
VendorGuid,
effectiveDataSize,
VariableName,
status);
return status;
}
/**
* @brief Handles SetVariable runtime service calls.
*/
static
EFI_STATUS
EFIAPI
HandleSetVariable (
IN CHAR16* VariableName,
IN EFI_GUID* VendorGuid,
IN UINT32 Attributes,
IN UINTN DataSize,
IN VOID* Data
)
{
EFI_STATUS status;
//
// Invoke the original SetVariable service, and log this service invocation.
//
status = g_SetVariable(VariableName, VendorGuid, Attributes, DataSize, Data);
DebugPrint(DEBUG_VERBOSE,
"S: %g Size=%08x %s: %r\n",
VendorGuid,
DataSize,
VariableName,
status);
return status;
}
/**
* @brief Converts global pointers from physical-mode ones to virtual-mode ones.
*/
static
VOID
EFIAPI
HandleSetVirtualAddressMap (
IN EFI_EVENT Event,
IN VOID* Context
)
{
EFI_STATUS status;
VOID* currentAddress;
currentAddress = (VOID*)g_GetVariable;
status = gRT->ConvertPointer(0, (VOID**)&g_GetVariable);
ASSERT_EFI_ERROR(status);
DEBUG((DEBUG_ERROR,
"GetVariable relocated from %p to %p\n",
currentAddress,
g_GetVariable));
currentAddress = (VOID*)g_SetVariable;
status = gRT->ConvertPointer(0, (VOID**)&g_SetVariable);
ASSERT_EFI_ERROR(status);
DEBUG((DEBUG_ERROR,
"SetVariable relocated from %p to %p\n",
currentAddress,
g_SetVariable));
}
/**
* @brief Exchanges a pointer in the EFI System Table.
*/
static
EFI_STATUS
ExchangePointerInServiceTable (
IN OUT VOID** AddressToUpdate,
IN VOID* NewPointer,
OUT VOID** OriginalPointer OPTIONAL
)
{
EFI_STATUS status;
EFI_TPL tpl;
ASSERT(*AddressToUpdate != NewPointer);
//
// Disable interrupt.
//
tpl = gBS->RaiseTPL(TPL_HIGH_LEVEL);
//
// Save the current value if needed and update the pointer.
//
if (OriginalPointer != NULL)
{
*OriginalPointer = *AddressToUpdate;
}
*AddressToUpdate = NewPointer;
//
// Update the CRC32 in the EFI System Table header.
//
gST->Hdr.CRC32 = 0;
status = gBS->CalculateCrc32(&gST->Hdr, gST->Hdr.HeaderSize, &gST->Hdr.CRC32);
ASSERT_EFI_ERROR(status);
gBS->RestoreTPL(tpl);
return status;
}
/**
* @brief Cleans up changes made by this module and release resources.
*
* @details This function handles pertical clean up and is safe for multiple calls.
*/
static
VOID
Cleanup (
VOID
)
{
EFI_STATUS status;
ASSERT(EfiAtRuntime() == FALSE);
if (gST->RuntimeServices->SetVariable == HandleSetVariable)
{
status = ExchangePointerInServiceTable(
(VOID**)&gST->RuntimeServices->SetVariable,
(VOID*)g_SetVariable,
NULL);
ASSERT_EFI_ERROR(status);
}
if (gST->RuntimeServices->GetVariable == HandleGetVariable)
{
status = ExchangePointerInServiceTable(
(VOID**)&gST->RuntimeServices->GetVariable,
(VOID*)g_GetVariable,
NULL);
ASSERT_EFI_ERROR(status);
}
if (g_SetVaMapEvent != NULL)
{
status = gBS->CloseEvent(&g_SetVaMapEvent);
ASSERT_EFI_ERROR(status);
g_SetVaMapEvent = NULL;
}
}
/**
* @brief The module entry point.
*/
EFI_STATUS
EFIAPI
UefiVarMonitorDxeInitialize (
IN EFI_HANDLE ImageHandle,
IN EFI_SYSTEM_TABLE* SystemTable
)
{
EFI_STATUS status;
DEBUG((DEBUG_ERROR, "Driver being loaded\n"));
//
// Register a notification for SetVirtualAddressMap call.
//
status = gBS->CreateEventEx(EVT_NOTIFY_SIGNAL,
TPL_CALLBACK,
HandleSetVirtualAddressMap,
NULL,
&gEfiEventVirtualAddressChangeGuid,
&g_SetVaMapEvent);
if (EFI_ERROR(status))
{
DEBUG((DEBUG_ERROR, "CreateEventEx failed : %r\n", status));
goto Exit;
}
//
// Install hooks.
//
status = ExchangePointerInServiceTable((VOID**)&gST->RuntimeServices->GetVariable,
(VOID*)HandleGetVariable,
(VOID**)&g_GetVariable);
if (EFI_ERROR(status))
{
DEBUG((DEBUG_ERROR, "ExchangeTablePointer(GetVariable) failed : %r\n", status));
goto Exit;
}
status = ExchangePointerInServiceTable((VOID**)&gST->RuntimeServices->SetVariable,
(VOID*)HandleSetVariable,
(VOID**)&g_SetVariable);
if (EFI_ERROR(status))
{
DEBUG((DEBUG_ERROR, "ExchangeTablePointer(SetVariable) failed : %r\n", status));
goto Exit;
}
Exit:
if (EFI_ERROR(status))
{
Cleanup();
}
return status;
}
/**
* @brief Handles unload request of this module.
*/
EFI_STATUS
EFIAPI
UefiVarMonitorDxeUnload (
IN EFI_HANDLE ImageHandle
)
{
Cleanup();
return EFI_SUCCESS;
}