两种方法获取shadow ssdt

ULONG 
GetShadowSsdtCurrentAddresses(
    PSSDT_ADDRESS   AddressInfo, 
    PULONG          Length
    )
{
    PSYSTEM_SERVICE_TABLE KeServiceDescriptorTableShadow = NULL;
    ULONG NumberOfService = 0;
    ULONG ServiceId = 0;
    PKAPC_STATE ApcState;
    ULONG i;
    
    if (AddressInfo == NULL || Length == NULL)
    {
        KdPrint(("[GetShadowSsdtCurrentAddresses] 输入参数无效"));
        return 0;
    }

    //KdPrint(("pid = %d", PsGetCurrentProcessId()));
    ServiceId = (ULONG)PsGetCurrentProcessId();

    if (!g_CsrssProcess) {
        PsLookupProcessByProcessId((PVOID)ScPsGetCsrssProcessId(), &g_CsrssProcess);
    }

    KeServiceDescriptorTableShadow = GetKeServiceDescriptorTableShadow();

    if (KeServiceDescriptorTableShadow == NULL)  
    {
        KdPrint(("[GetShadowSsdtCurrentAddresses] GetKeServiceDescriptorTableShadow failed"));
        return 0;
    }

    NumberOfService = KeServiceDescriptorTableShadow->NumberOfService;
    if (Length[0] < NumberOfService * sizeof(SSDT_ADDRESS))
    {
        Length[0] = NumberOfService * sizeof(SSDT_ADDRESS);
        return 0;
    }

    ApcState = ExAllocatePoolWithTag(NonPagedPool, sizeof(KAPC_STATE), MEM_TAG);
    KeStackAttachProcess((PRKPROCESS)g_CsrssProcess, ApcState);

    for (ServiceId = 0; ServiceId < NumberOfService; ServiceId ++)
    {
        AddressInfo[ServiceId].FunAddress = (ULONG)
            KeServiceDescriptorTableShadow->ServiceTableBase[ServiceId];
        AddressInfo[ServiceId].nIndex = ServiceId;
    }

    KeUnstackDetachProcess(ApcState);
    ExFreePool(ApcState);

    Length[0] = NumberOfService * sizeof(SSDT_ADDRESS);
    return NumberOfService;
}

///////////////////////////////////////////////////////////////////////////////////
//
//    功能实现：枚举当前Shadow SSDT 表函数地址
//    输入参数：void
//    输出参数：返回Shadow ssdt table
//
///////////////////////////////////////////////////////////////////////////////////
PSYSTEM_SERVICE_TABLE 
GetKeServiceDescriptorTableShadow(VOID)
{
    PSYSTEM_SERVICE_TABLE ShadowTable = NULL;
    ULONG   ServiceTableAddress = 0;
    PUCHAR  cPtr = NULL; 

    for (cPtr = (PUCHAR)KeAddSystemServiceTable;
         cPtr < (PUCHAR)KeAddSystemServiceTable + PAGE_SIZE;
         cPtr += 1 )
    {
        if (!MmIsAddressValid(cPtr))  continue;

        ServiceTableAddress = *(PULONG)cPtr;
        if (!MmIsAddressValid((PVOID)ServiceTableAddress)) continue;

        if (memcmp((PVOID)ServiceTableAddress, &KeServiceDescriptorTable, 16) == 0)
        {
            if ((PVOID)ServiceTableAddress == &KeServiceDescriptorTable) continue;
            ShadowTable = (PSYSTEM_SERVICE_TABLE)ServiceTableAddress;
            ShadowTable ++;
            return ShadowTable;
        }
    }
    return NULL;
}
//
// 方法2，通过硬编码实现，不通用
// 
PSYSTEM_SERVICE_TABLE 
GetKeServiceDescriptorTableShadow_2(VOID)
/*++
    805ba5a3 8d8840a65580    lea    ecx,nt!KeServiceDescriptorTableShadow (8055a640)[eax]
    805ba5a9 833900          cmp    dword ptr [ecx],0
--*/
{
    PSYSTEM_SERVICE_TABLE ShadowTable;
    ULONG   ServiceTableAddress;
    PUCHAR  cPtr, pOpcode;
    ULONG   Length = 0;

    for (cPtr = (PUCHAR)KeAddSystemServiceTable;
         cPtr < (PUCHAR)KeAddSystemServiceTable + PAGE_SIZE;
         cPtr += Length )
    {
        if (!MmIsAddressValid(cPtr))  return NULL;

        Length = SizeOfCode(cPtr, &pOpcode);

        if (!Length || (Length == 1 && *pOpcode == 0xC3)) return NULL;

        if (*(PUSHORT)pOpcode == 0x888D)
        {
            ServiceTableAddress = *(PULONG)(pOpcode + 2);
            ShadowTable = (PSYSTEM_SERVICE_TABLE)ServiceTableAddress;
            ShadowTable ++;
            return ShadowTable;
        }
    }
    return NULL;
}