From: "Tony Mason" <mason@osr.com>
Newsgroups: comp.os.ms-windows.programmer.nt.kernel-mode
References: <664inb$6sq$1@heliodor.xara.net>
Subject: Re: Accessing a Remote File - Help!
Date: Fri, 5 Dec 1997 20:58:38 -0500
Lines: 83
Organization: OSR Open Systems Resources, Inc.
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The return value you receive (STATUS_ACCESS_DENIED) indicates you are
performing the open correctly.  You just don't have access to the file.

In general, a kernel mode driver operates with the credentials presently
registered for the thread (or process) that is performing the operation.
Since every workstation has its own credentials, independent of anyone
logged onto the system, if you try to run in a system thread you will be
using the system credentials.  As a matter of general policy, NT
workstations don't trust one another (I suppose you could modify this
policy, although I know of no documented way to accomplish this.)

Most likely the simplest solution to your problem is to build a Win32
service.  Set it up so that it "logs on" to an account with credentials.
Then, perform your operations in threads passed to your driver from your
service.  You will then be using the service credentials and the operation
will succeed if you have permission to access the file (which it should if
you set up the account correctly.)

Best of luck on your project!

Regards,

Tony

Tony Mason
Consulting Partner
OSR Open Systems Resources, Inc.
mason@osr.com
http://www.osr.com



Mark Morley wrote in message <664inb$6sq$1@heliodor.xara.net>...
>I need some help - I'm trying to access a remote file from my driver.
>
>First Question - Is it possible to access the file remotely? (From my
driver
>before any users have logged on).
>
>Second Question - Am I on the right track?
>
>The file is on a remote machine called SERVER under a share called Config
in
>a file called Cardconfig.ini.
>
>The following code snippet returns STATUS_ACCESS_DENIED
>
> RtlInitUnicodeString( &ntUnicodeString,
>L"\\Device\\Mup\\SERVER\\Config\\Cardconfig.ini");
> InitializeObjectAttributes( &objectAttributes, &ntUnicodeString,
>OBJ_INHERIT|OBJ_CASE_INSENSITIVE|OBJ_OPENIF , NULL, NULL );
> ntStatus = ZwCreateFile(&ntFileHandle,
>       FILE_READ_ACCESS,
>       &objectAttributes,
>       &ioStatus,
>       NULL,
>       0,
>       FILE_SHARE_READ,
>       FILE_OPEN,
>       FILE_SYNCHRONOUS_IO_NONALERT,
>       NULL,
>       0 );
>
>I've also tried creating a security descriptor with
>RtlCreateSecurityDescriptor, and set some of its members with
>RtlSetDaclSecurityDescriptor
>and then passed a pointer to it into the InitializeObjectAttributes
>function, but again I keep getting STATUS_ACCESS_DENIED.
>
>PSECURITY_DESCRIPTOR  psd;
> ntStatus = RtlCreateSecurityDescriptor(psd, 1);
> ntStatus = RtlSetDaclSecurityDescriptor(psd, TRUE, NULL, TRUE); // a NULL
>DACL unconditionally grants access ????
>
>I've tried many different conbinations of parameters for all the functions!
>
>Any help most gratefully received.
>
>Mark Morley
>
>