Removable media enc/dec driver design.

NTFSD
1

I have a driver which encrypts/decrypts removable medias. There is a Vista specific problem. When encrypted RM is inserted, Vista gives a dialogbox:

You need to format the disk in drive E: before you can use it.
Do you want to format it?

Have you any ideas how can I prevent this?

Thank you…

2

It is Filesystem OR Filter driver.

On Fri, May 22, 2009 at 11:39 AM, wrote:

> I have a driver which encrypts/decrypts removable medias. There is a Vista
> specific problem. When encrypted RM is inserted, Vista gives a dialogbox:
>
> You need to format the disk in drive E: before you can use it.
> Do you want to format it?
>
> Have you any ideas how can I prevent this?
>
> Thank you…
>
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With Best Regards
Vijay Kumar

3

It is filter driver.

4

> You need to format the disk in drive E: before you can use it.

This means that the disk does not contain a recognized file system, and no FSD in Windows could mount.

Some bug in your filtering.

–
Maxim S. Shatskih
Windows DDK MVP
xxxxx@storagecraft.com
http://www.storagecraft.com

5

Yes I know.
I have read documentation in http://www.microsoft.com/whdc/device/storage/remstorperms.mspx, and here is a good part:

Volume Manager and File System Stacks for Hot-Pluggable Devices.
Windows constructs a volume manager stack for the storage medium on the disk, which is managed by the volume manager driver. If the media is formatted, a file system stack is mounted for whatever file system was used to format the disk?FAT, FAT32, and so on.

Which control code is responsible for this work?

P.S. My driver changes first sector, that’s why I get Format dialog.

6

xxxxx@gmail.com wrote:

Yes I know.
I have read documentation in http://www.microsoft.com/whdc/device/storage/remstorperms.mspx, and here is a good part:

Volume Manager and File System Stacks for Hot-Pluggable Devices.
Windows constructs a volume manager stack for the storage medium on the disk, which is managed by the volume manager driver. If the media is formatted, a file system stack is mounted for whatever file system was used to format the disk?FAT, FAT32, and so on.

Which control code is responsible for this work?

P.S. My driver changes first sector, that’s why I get Format dialog.

Without debugging this I’m relying on psychic powers only, but I’d guess
that the file system recogniser (fsrec) is trying to determine which
filesystem to load and can’t find it because the bootsector it’s using
is modified. Since your filter isn’t attached yet (the stack isn’t
created), you can’t (yet) correct the condition.

I’d also guess that you’re testing on FAT, and this is working pre-Vista
because fastfat is loaded before the media arrives (which it is not on
Vista.) If you loaded fastfat then inserted the media, the result may
change.

  • M

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