Stop attach device

NTDEV
1

How to stop attaching another device to my device in device stack. I want
always to be on the top of the device stack.

THANKS

2

Dimityr Andreev wrote:

How to stop attaching another device to my device in device stack. I want
always to be on the top of the device stack.

You can’t stop the PnP Manager from loading a filter driver above you
and calling its AddDevice function, which will then do an
IoAttachDeviceToDeviceStack. Nor can you stop someone in kernel mode
from locating your device object and sending you IRPs. What you could do
is any of the following:

  1. Notice that the AttachedDevice field in your DEVICE_OBJECT is not
    NULL, which would imply that someone has attached above you, whereupon
    you could complain in some fashion.

  2. Fail IRP_MJ_CREATE in an attempt to prevent someone from using
    IoGetDeviceObjectPointer. Of course, this *also* prevents anyone from
    opening a handle to your device, so it’s not likely to be a good
    solution.

  3. From user mode, use
    SetupDiGetDeviceRegistryProperty(SPDRP_UPPERFILTERS) to see if anyone is
    listed as a device upper filter. To check for class upper filters, use
    SetupDiOpenClassRegKey to open the class key and check explicitly for an
    UpperFilters entry.

All of this said, *why* do you need to be the top of the stack, given
that you really can’t force that to be true?

–
Walter Oney, Consulting and Training
Check out new US seminar schedule at http://www.oneysoft.com

3

In Solution 2. Correct me if i am wrong which i might be.
If i fail IRP_MJ_CREATE. i being filter driver i thought no one could open a
handle to the device i am filtering also.

Am i wrong?

-Srin.

-----Original Message-----
From: Walter Oney [mailto:xxxxx@oneysoft.com]
Sent: Wednesday, September 18, 2002 7:28 AM
To: NT Developers Interest List
Subject: [ntdev] Re: Stop attach device

Dimityr Andreev wrote:

How to stop attaching another device to my device in device stack. I want
always to be on the top of the device stack.

You can’t stop the PnP Manager from loading a filter driver above you
and calling its AddDevice function, which will then do an
IoAttachDeviceToDeviceStack. Nor can you stop someone in kernel mode
from locating your device object and sending you IRPs. What you could do
is any of the following:

  1. Notice that the AttachedDevice field in your DEVICE_OBJECT is not
    NULL, which would imply that someone has attached above you, whereupon
    you could complain in some fashion.

  2. Fail IRP_MJ_CREATE in an attempt to prevent someone from using
    IoGetDeviceObjectPointer. Of course, this *also* prevents anyone from
    opening a handle to your device, so it’s not likely to be a good
    solution.

  3. From user mode, use
    SetupDiGetDeviceRegistryProperty(SPDRP_UPPERFILTERS) to see if anyone is
    listed as a device upper filter. To check for class upper filters, use
    SetupDiOpenClassRegKey to open the class key and check explicitly for an
    UpperFilters entry.

All of this said, *why* do you need to be the top of the stack, given
that you really can’t force that to be true?

–
Walter Oney, Consulting and Training
Check out new US seminar schedule at http://www.oneysoft.com

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