In a minifilter, how do I get the path the file was opened with?

In a Windows minifilter driver, you can retrieve the path of the file that was opened by intercepting the IRP_MJ_CREATE callback. Here's a high-level overview of how to achieve this:

1. Register the minifilter driver: Ensure that your minifilter driver is properly registered and loaded in the system.

2. Implement the Callback Function: You need to implement a callback function for the IRP_MJ_CREATE operation. This callback will be called when a file is opened.

3. Access the File Object: Inside the callback function, you can access the FILE_OBJECT structure associated with the file operation. The FILE_OBJECT contains information about the file, including its path.

Here's a simplified example of what the callback function might look like:

cCopy code
FLT_PREOP_CALLBACK_STATUS

PreCreateCallback(

    _Inout_ PFLT_CALLBACK_DATA Data,

    _In_ PCFLT_RELATED_OBJECTS FltObjects,

    _Outptr_result_maybenull_ PVOID *CompletionContext

)

{

    PFILE_OBJECT fileObject = FltObjects->FileObject;



    if (fileObject) {

        UNICODE_STRING filePath = fileObject->FileName;

        // Now you can use filePath to access the path of the opened file

    }



    return FLT_PREOP_SUCCESS_NO_CALLBACK;

}

Please note that working with minifilters requires a deep understanding of the Windows I/O stack and kernel-mode programming. Proper error handling, synchronization, and dealing with Unicode strings are critical in minifilter development. Also, minifilter drivers operate at a low level in the kernel, so errors or bugs can have severe consequences for system stability.

Ensure you follow Microsoft's guidelines and best practices for minifilter development and thoroughly test your code in a controlled environment before deploying it to a production system.