Need help using NtCreateFile() to open by fileIndex

Question

I have written a program that queries the change journal records and lists them. The change journal returns:

1) filereferencenumber( combination of fileindex.high and fileindex.low) 2) parentfilereferencenumber(same as above except it is for directory) 3) szReason(Reason it appears in the change record) 4) Filename and Filelength.

I want to find the path of this file listed in the change journal. Most of the implementations I have seen keep track of all the filereferencenumber and query it to compare, or they use FindNextFile() functions ot traverse through the entire volume.

I came across a discussion where they say, they can open a file handle using just the filereferencenumber. http://www.tech-archive.net/Archive/Windows/microsoft.public.windows.file_system/2004-11/0244.html

The msdn article says, we have to load a library before calling Internal API's http://msdn.microsoft.com/en-us/library/bb432380%28v=vs.85%29.aspx

Can someone point me in the right direction and tell me exactly what to do? How do I use NtCreateFile()?

Or, is there a way to access file path using just the filereferencenumber?

Shaylyn

That isn't exactly how StackOverflow is supposed to work. Questions remain so that future people can find the answer. – Infection

Sorry @Zan Lynx, was a bit of a desperation, and I posted the question. And, since I owe everyone an answer, I posted it below as well. – Shaylyn

Answer 1

Here is the code I used: http://www.ragestorm.net/blogs/?cat=7

 #include windows.h
 typedef ULONG (__stdcall *pNtCreateFile)(
   PHANDLE FileHandle,
   ULONG DesiredAccess,
   PVOID ObjectAttributes,
   PVOID IoStatusBlock,
   PLARGE_INTEGER AllocationSize,
   ULONG FileAttributes,
   ULONG ShareAccess,
   ULONG CreateDisposition,
   ULONG CreateOptions,
   PVOID EaBuffer,
   ULONG EaLength
 );

 typedef ULONG (__stdcall *pNtReadFile)(
    IN HANDLE  FileHandle,
    IN HANDLE  Event  OPTIONAL,
    IN PVOID  ApcRoutine  OPTIONAL,
    IN PVOID  ApcContext  OPTIONAL,
    OUT PVOID  IoStatusBlock,
    OUT PVOID  Buffer,
    IN ULONG  Length,
    IN PLARGE_INTEGER  ByteOffset  OPTIONAL,
    IN PULONG  Key  OPTIONAL    );

 typedef struct _UNICODE_STRING {
    USHORT Length, MaximumLength;
    PWCH Buffer;
 } UNICODE_STRING, *PUNICODE_STRING;

 typedef struct _OBJECT_ATTRIBUTES {
 ULONG Length;
 HANDLE RootDirectory;
 PUNICODE_STRING ObjectName;
 ULONG Attributes;
 PVOID SecurityDescriptor;        // Points to type SECURITY_DESCRIPTOR
PVOID SecurityQualityOfService;  // Points to type SECURITY_QUALITY_OF_SERVICE
 } OBJECT_ATTRIBUTES;

 #define InitializeObjectAttributes( p, n, a, r, s ) { \
(p)->Length = sizeof( OBJECT_ATTRIBUTES );          \
(p)->RootDirectory = r;                             \
(p)->Attributes = a;                                \
(p)->ObjectName = n;                                \
(p)->SecurityDescriptor = s;                        \
(p)->SecurityQualityOfService = NULL;               \
}

 #define OBJ_CASE_INSENSITIVE  0x00000040L
 #define FILE_NON_DIRECTORY_FILE  0×00000040
 #define FILE_OPEN_BY_FILE_ID  0×00002000
 #define FILE_OPEN   0×00000001

 int main(int argc, char* argv[])
 {
    HANDLE d = CreateFile(L"\\\\.\\c:", GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE, 0, OPEN_EXISTING, 0, 0  );
    BY_HANDLE_FILE_INFORMATION i;
    HANDLE f = CreateFile(L"c:\\bla.bla", GENERIC_WRITE, 0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
    ULONG bla;
    WriteFile(f, "helloworld", 11, &bla, NULL);
    printf("%x, %d\n", f, GetLastError());
    GetFileInformationByHandle(f, &i);
    printf("id:%08x-%08x\n", i.nFileIndexHigh, i.nFileIndexLow);
    CloseHandle(f);

    pNtCreateFile NtCreatefile = (pNtCreateFile)GetProcAddress(GetModuleHandle(L"ntdll.dll"), "NtCreateFile");
    pNtReadFile NtReadFile = (pNtReadFile)GetProcAddress(GetModuleHandle(L"ntdll.dll"), "NtReadFile");

    ULONG fid[2] = {i.nFileIndexLow, i.nFileIndexHigh};
    UNICODE_STRING fidstr = {8, 8, (PWSTR) fid};

    OBJECT_ATTRIBUTES oa = {0};
     InitializeObjectAttributes (&oa, &fidstr, OBJ_CASE_INSENSITIVE, d, NULL);

     ULONG iosb[2];
     ULONG status = NtCreatefile(&f, GENERIC_ALL, &oa, iosb, NULL, FILE_ATTRIBUTE_NORMAL, FILE_SHARE_READ | FILE_SHARE_WRITE, FILE_OPEN, FILE_OPEN_BY_FILE_ID | FILE_NON_DIRECTORY_FILE, NULL, 0);
    printf("status: %X, handle: %x\n", status, f);
    UCHAR buf[11] = {0};
    LONG Off[2] = {0};
    status = NtReadFile(f, NULL, NULL, NULL, (PVOID)&iosb, (PVOID)buf, sizeof(buf), (PLARGE_INTEGER)&Off, NULL);
    printf("status: %X, bytes: %d\n", status, iosb[1]);
    printf("buf: %s\n", buf);
    CloseHandle(f);
    CloseHandle(d);
 }

As you can see, once you give the fileindex.high and fileindex.low part of the filereferencenumber, it gives you a handle to that file. And I used getFileMapping function from psapi, to get the full path. Information for those curious: http://msdn.microsoft.com/en-us/library/aa366789.aspx

Shaylyn

Pro tip: ULONG iosb[2] only works for 32bit. If you aren't going to use an actual IO_STATUS_BLOCK, then perhaps ULONG_PTR iosb[2]; would be better. – Shovel