Windows System Software -- Consulting, Training, Development -- Unique Expertise, Guaranteed Results

Home NTFSD

Before Posting...

Please check out the Community Guidelines in the Announcements and Administration Category.

More Info on Driver Writing and Debugging


The free OSR Learning Library has more than 50 articles on a wide variety of topics about writing and debugging device drivers and Minifilters. From introductory level to advanced. All the articles have been recently reviewed and updated, and are written using the clear and definitive style you've come to expect from OSR over the years.


Check out The OSR Learning Library at: https://www.osr.com/osr-learning-library/


Monitor mapped file writes

alonwalonw Member Posts: 1

Hi, I am currently writing a minifilter. As part of the minifilter I monitor for file writes (to test file data before and after a write).
When looking on a mapped file, I first monitor IRP_MJ_ACQUIRE_FOR_SECTION_SYNCHRONIZATION and check the data in the file, then I monitor IRP_MJ_CLEANUP and check for a change in the file data.
This is not good enough since it is possible to close the handles before the file is written to.
I wrote two POCs, one using passthrough from Windows-driver-samples. In this POC I monitor all IRPs and log them. The second POC is for mapping a file, closing its handles and only then writing to the mapped view.
Minifilter POC:

CONST FLT_OPERATION_REGISTRATION Callbacks[] = {
    { IRP_MJ_CREATE,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_CREATE_NAMED_PIPE,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_CLOSE,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_READ,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_WRITE,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_QUERY_INFORMATION,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_SET_INFORMATION,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_QUERY_EA,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_SET_EA,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_FLUSH_BUFFERS,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_QUERY_VOLUME_INFORMATION,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_SET_VOLUME_INFORMATION,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_DIRECTORY_CONTROL,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_FILE_SYSTEM_CONTROL,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_DEVICE_CONTROL,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_INTERNAL_DEVICE_CONTROL,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_SHUTDOWN,
      0,
      PtPreOperationNoPostOperationPassThrough,
      NULL },                               //post operations not supported

    { IRP_MJ_LOCK_CONTROL,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_CLEANUP,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_CREATE_MAILSLOT,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_QUERY_SECURITY,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_SET_SECURITY,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_QUERY_QUOTA,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_SET_QUOTA,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_PNP,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_ACQUIRE_FOR_SECTION_SYNCHRONIZATION,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_RELEASE_FOR_SECTION_SYNCHRONIZATION,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_ACQUIRE_FOR_MOD_WRITE,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_RELEASE_FOR_MOD_WRITE,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_ACQUIRE_FOR_CC_FLUSH,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_RELEASE_FOR_CC_FLUSH,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_FAST_IO_CHECK_IF_POSSIBLE,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_NETWORK_QUERY_OPEN,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_MDL_READ,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_MDL_READ_COMPLETE,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_PREPARE_MDL_WRITE,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_MDL_WRITE_COMPLETE,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_VOLUME_MOUNT,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_VOLUME_DISMOUNT,
      0,
      PtPreOperationPassThrough,
      PtPostOperationPassThrough },

    { IRP_MJ_OPERATION_END }
};

File mapper POC (calling writeFile which calls mapFile):

char* mapFile(std::string filePath, BOOL isRead, HANDLE* hFile, HANDLE* hFileMapping)
{
    DWORD filesize = 0;
    if (isRead)
    {
        *hFile = CreateFileA(filePath.c_str(), GENERIC_WRITE | GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
        if (*hFile == INVALID_HANDLE_VALUE) return NULL;
        DWORD highSize;
        filesize = GetFileSize(*hFile, &highSize);
    }
    else
    {
        *hFile = CreateFileA(filePath.c_str(), GENERIC_WRITE | GENERIC_READ, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
        if (*hFile == INVALID_HANDLE_VALUE) return NULL;
        filesize = sizeof(dataToWrite);
    }



    *hFileMapping = CreateFileMapping(*hFile, NULL, PAGE_READWRITE, 0, filesize, NULL);
    if (*hFileMapping == NULL)
    {
        CloseHandle(*hFile);
        return NULL;
    }
    char* viewData = (char*)MapViewOfFile(*hFileMapping, FILE_MAP_ALL_ACCESS, 0, 0, filesize);
    if (viewData == NULL)
    {

    }
    CloseHandle(*hFileMapping);
    CloseHandle(*hFile);
    return viewData;

}

**BOOL writeFile(std::string filePath)**
{
    HANDLE hFile;
    HANDLE hFileMapping;
    char* viewData = mapFile(filePath, FALSE, &hFile, &hFileMapping);
    if (viewData == NULL)
    {
        return FALSE;
    }

    CopyMemory(viewData, dataToWrite, sizeof(dataToWrite));
    unmapFile(viewData, hFile, hFileMapping);
    return TRUE;
}

When running the POC I looked at the logs and couldn't find any writes to the file after an IRP_MJ_CLEANUP is issued, only IRP_MJ_READ.

Logs:

Process name: \Device\HarddiskVolume4\Users\user\Desktop\FileMappingRW64.exe PID: 6332 IRP: IRP_MJ_CREATE 
Process name: \Device\HarddiskVolume4\Users\user\Desktop\FileMappingRW64.exe PID: 6332 IRP: IRP_MJ_ACQUIRE_FOR_SECTION_SYNCHRONIZATION 
Process name: \Device\HarddiskVolume4\Users\user\Desktop\FileMappingRW64.exe PID: 6332 IRP: IRP_MJ_QUERY_INFORMATION 
Process name: \Device\HarddiskVolume4\Users\user\Desktop\FileMappingRW64.exe PID: 6332 IRP: IRP_MJ_RELEASE_FOR_SECTION_SYNCHRONIZATION 
Process name: \Device\HarddiskVolume4\Users\user\Desktop\FileMappingRW64.exe PID: 6332 IRP: IRP_MJ_QUERY_INFORMATION 
Process name: \Device\HarddiskVolume4\Users\user\Desktop\FileMappingRW64.exe PID: 6332 IRP: IRP_MJ_SET_INFORMATION 
Process name: \Device\HarddiskVolume4\Users\user\Desktop\FileMappingRW64.exe PID: 6332 IRP: IRP_MJ_ACQUIRE_FOR_SECTION_SYNCHRONIZATION 
Process name: \Device\HarddiskVolume4\Users\user\Desktop\FileMappingRW64.exe PID: 6332 IRP: IRP_MJ_RELEASE_FOR_SECTION_SYNCHRONIZATION 
Process name: \Device\HarddiskVolume4\Users\user\Desktop\FileMappingRW64.exe PID: 6332 IRP: IRP_MJ_CLEANUP 
Process name: \Device\HarddiskVolume4\Users\user\Desktop\FileMappingRW64.exe PID: 6332 IRP: IRP_MJ_CLOSE 
Process name: \Device\HarddiskVolume4\Users\user\Desktop\FileMappingRW64.exe PID: 6332 IRP: IRP_MJ_READ 

Am I doing something wrong? is there a way to monitor a write to the mapped view?
After a while I do see the write from the system process but it is too late.
Let me know if additional data is required.

Thanks!

Comments

  • Scott_Noone_(OSR)Scott_Noone_(OSR) Administrator Posts: 3,496

    This is the way memory mapped writes work. There's no way to know the moment that the page is marked dirty, you'll just eventually see a paging write drizzle out from the System process (unless the application explicitly flushes).

    -scott
    OSR

Sign In or Register to comment.

Howdy, Stranger!

It looks like you're new here. Sign in or register to get started.

Upcoming OSR Seminars
OSR has suspended in-person seminars due to the Covid-19 outbreak. But, don't miss your training! Attend via the internet instead!
Writing WDF Drivers 12 September 2022 Live, Online
Internals & Software Drivers 23 October 2022 Live, Online
Kernel Debugging 14 November 2022 Live, Online
Developing Minifilters 5 December 2022 Live, Online