Following is some C++ source code for a Windows kernel-driver service loader. It could be used to load other service types too by changing the dwServiceType flag on the CreateService call. I threw this together for another project I am currently working on. It is also used in the following post (posting soon).
It works in the following way:
- It is a command line utility which takes 3 arguments:
- The service name. Hereby referred to as SERVICE_NAME
- The service display name. Hereby referred to as DISPLAY_NAME
- The driver path (to the .sys file). Hereby referred to as DRIVER_PATH
- This program (most likely) requires administrative access. There are also some caveats regarding driver code signing requirements that are thoroughly explored elsewhere.
- It first checks to see if a service already exists with the given SERVICE_NAME. If it does:
- If the DISPLAY_NAME matches, the service is kept as is.
- If the DISPLAY_NAME does not match, the user is prompted on if they want to delete the current service. If they do not, the program exits.
- If the service needs to be created (it did not already exist or was deleted), it creates the service with the given SERVICE_NAME, DISPLAY_NAME, and DRIVER_PATH. If the service is not created during this run, the DRIVER_PATH is ignored.
Note: The DRIVER_PATH must be to a direct local file system file. I have found that network links and symbolic links do not work. - The service is started up:
- If it is already running, the user is prompted on if they want to stop the currently running service. If they say no, the program exits.
- The program then waits for a final user input on if they want to close the service before exiting the program.
- If there was an error, the program reports the error, otherwise, it reports “Success”.
- The program pauses at the end until the user presses any key to exit.
- The program returns 0 on success, and 1 if an error occurred.
//Compiler flags
#define WIN32_LEAN_AND_MEAN //Include minimum amount of windows stuff
#ifndef _UNICODE //Everything in this script is unicode
#define _UNICODE
#endif
#include <windows.h>
#include <stdio.h>
#include <conio.h>
#include <memory>
//Smart pointers
typedef std::unique_ptr<WCHAR, void(*)(WCHAR*)> SmartWinAlloc;
typedef std::unique_ptr<SC_HANDLE, void(*)(SC_HANDLE*)> SmartCloseService;
void Delete_SmartWinAlloc(WCHAR *p) { if(p) LocalFree(p); }
void Delete_SmartCloseService(SC_HANDLE *h) { if(h && *h) CloseServiceHandle(*h); }
//Function declarations
WCHAR* InitDriver(int argc, WCHAR *argv[]);
WCHAR* FormatError(WCHAR* Format, ...);
SmartWinAlloc GetLastErrorStr();
BOOLEAN AskQuestion(WCHAR* Question); //Returns if user answered yes
int wmain(int argc, WCHAR *argv[])
{
//Run the init routine
WCHAR* Ret=InitDriver(argc, argv);
//If there is an error, report it, or otherwise, report success
wprintf(L"%s\n", Ret ? Ret : L"Success");
wprintf(L"%s\n", L"Press any key to exit");
_getch();
//Return if successful
return (Ret ? 1 : 0);
}
WCHAR* InitDriver(int argc, WCHAR *argv[])
{
//Confirm arguments
if(argc<4)
return FormatError(L"%s", L"3 arguments are required: Service Name, Display Name, Driver Path");
const WCHAR* Param_ServiceName=argv[1];
const WCHAR* Param_DisplayName=argv[2];
const WCHAR* Param_DriverPath =argv[3];
//Open the service manager
wprintf(L"%s\n", L"Opening the service manager");
SC_HANDLE HSCManager=OpenSCManager(nullptr, nullptr, SC_MANAGER_CREATE_SERVICE);
if(!HSCManager)
return FormatError(L"%s: %s", L"Error opening service manager", GetLastErrorStr());
SmartCloseService FreeHSCManager(&HSCManager, Delete_SmartCloseService);
//Check if the service already exists
wprintf(L"%s\n", L"Checking previously existing service state");
BOOL ServiceExists=false;
{
//Get the service name
const DWORD NameBufferSize=255;
WCHAR NameBuffer[NameBufferSize];
WCHAR *NamePointer=NameBuffer;
DWORD NamePointerSize=NameBufferSize;
std::unique_ptr<WCHAR> Buf(nullptr); //May be swapped with a real pointer later
for(INT_PTR i=0;i<2;i++)
{
//If we found the service, exit the lookup here
if(GetServiceDisplayName(HSCManager, Param_ServiceName, NamePointer, &NamePointerSize))
{
ServiceExists=true;
break;
}
//If the service does not exist, we can exit the lookup here
if(GetLastError()==ERROR_SERVICE_DOES_NOT_EXIST)
break;
//If error is not insufficient buffer size, return the error
if(GetLastError()!=ERROR_INSUFFICIENT_BUFFER)
return FormatError(L"%s: %s", L"Could not query service information", GetLastErrorStr());
//If second pass, error out
if(i==1)
return FormatError(L"%s: %s", L"Could not query service information", L"Second buffer pass failed");
//Create a buffer of appropriate size (and make sure it will later be released)
NamePointer=new WCHAR[++NamePointerSize];
std::unique_ptr<WCHAR> Buf2(NamePointer);
Buf.swap(Buf2);
}
//If the service already exists, confirm the service name matches, and if not, ask if user wants to delete the current service
if(ServiceExists)
{
wprintf(L"%s\n", L"The service already exists");
if(wcsncmp(NamePointer, Param_DisplayName, NamePointerSize+1))
{
//If the server names do not match, ask the user what to do
wprintf(L"%s:\nCurrent: %s\nRequested: %s\n", L"The service names do not match", NamePointer, Param_DisplayName);
//Make the request
if(!AskQuestion(L"Would you like to replace the service? (y/n)")) //If user does not wish to replace the service
return FormatError(L"%s", L"Cannot continue if service names do not match");
//Delete the service
wprintf(L"%s\n", L"Deleting the old service");
ServiceExists=false;
SC_HANDLE TheService=OpenService(HSCManager, Param_ServiceName, DELETE);
if(!TheService)
return FormatError(L"%s: %s", L"Could not open the service to delete it", GetLastErrorStr());
SmartCloseService CloseTheService(&TheService, Delete_SmartCloseService); //Close the service handle
if(!DeleteService(TheService))
return FormatError(L"%s: %s", L"Could not delete the service", GetLastErrorStr());
wprintf(L"%s\n", L"The service has been deleted");
}
}
}
//Create the service
SC_HANDLE TheService;
if(!ServiceExists)
{
//Confirm the driver path exists
wprintf(L"%s\n", L"Checking the driver file");
DWORD FileAttrs=GetFileAttributes(Param_DriverPath);
if(FileAttrs==INVALID_FILE_ATTRIBUTES)
return FormatError(L"%s: %s", L"Given path is invalid", GetLastErrorStr());
if(FileAttrs&FILE_ATTRIBUTE_DIRECTORY)
return FormatError(L"%s: %s", L"Given path is invalid", L"Path is a folder");
//Create the service
wprintf(L"%s\n", L"Creating the service");
TheService=CreateService(
HSCManager, Param_ServiceName, Param_DisplayName,
SERVICE_START|SERVICE_STOP,
SERVICE_KERNEL_DRIVER, SERVICE_DEMAND_START, SERVICE_ERROR_IGNORE,
Param_DriverPath, nullptr, nullptr, nullptr, nullptr, nullptr);
if(!TheService)
return FormatError(L"%s: %s", L"Could not create the service", GetLastErrorStr());
//Open the service if not creating
} else {
TheService=OpenService(HSCManager, Param_ServiceName, SERVICE_START|SERVICE_STOP);
if(!TheService)
return FormatError(L"%s: %s", L"Could not open the service", GetLastErrorStr());
}
SmartCloseService CloseTheService(&TheService, Delete_SmartCloseService); //Close the service on exit
//Start the service
wprintf(L"%s\n", L"Starting the service");
for(INT_PTR i=0;i<2;i++)
{
if(StartService(TheService, 0, nullptr))
break;
//If not "service already running" error, or user does not want to stop the current service
if(i==1 || GetLastError()!=ERROR_SERVICE_ALREADY_RUNNING || !AskQuestion(L"The service is already running. Would you like to stop it? (y/n)"))
return FormatError(L"%s: %s", L"Could not start the service", GetLastErrorStr());
//Stop the service
SERVICE_STATUS ss;
wprintf(L"%s\n", L"Stopping the current service");
if(!ControlService(TheService, SERVICE_CONTROL_STOP, &ss))
return FormatError(L"%s: %s", L"Could not stop the current service", GetLastErrorStr());
}
wprintf(L"%s\n", L"Started the service");
//Ask if the user wants to close the service
if(!AskQuestion(L"Would you like to stop the service before exit? (y/n)"))
return nullptr;
//Stop the service
SERVICE_STATUS ss;
if(!ControlService(TheService, SERVICE_CONTROL_STOP, &ss))
return FormatError(L"%s: %s", L"Could not stop the service", GetLastErrorStr());
if(ss.dwCurrentState!=SERVICE_STOP_PENDING && ss.dwCurrentState!=SERVICE_STOPPED)
return FormatError(L"%s", L"The service does not appear to be closing");
wprintf(L"%s\n", L"The service has been stopped");
//Return success
return nullptr;
}
WCHAR* FormatError(WCHAR* Format, ...)
{
static WCHAR Err[255];
va_list VAList;
va_start(VAList, Format);
vswprintf(Err, sizeof(Err)/sizeof(Err[0]), Format, VAList);
return Err;
}
SmartWinAlloc GetLastErrorStr()
{
LPWSTR MessageBuffer=nullptr;
FormatMessage(
FORMAT_MESSAGE_ALLOCATE_BUFFER|FORMAT_MESSAGE_FROM_SYSTEM|FORMAT_MESSAGE_IGNORE_INSERTS|FORMAT_MESSAGE_MAX_WIDTH_MASK,
nullptr, GetLastError(), MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPWSTR)&MessageBuffer, 0, nullptr);
return SmartWinAlloc(MessageBuffer, Delete_SmartWinAlloc);
}
BOOLEAN AskQuestion(WCHAR* Question)
{
//Make the request and wait for an input character
while(1)
{
//Ask the question and get the answer
wprintf(L"%s:", Question);
fflush(stdout);
char InputChar=_getch();
printf("\n");
//Check for a valid answer
if(InputChar=='n' || InputChar=='N')
return FALSE;
if(InputChar=='y' || InputChar=='Y')
return TRUE;
}
}