User Impersonation on Win XP SP2

[vipleo]

I am having some issues, when I try to launch another process using
Process.Start(P rocessStartInfo psi) on win xp sp2 box (Other versions
of xp have no issue).

Here is the detail.
Main app checks for updates on startup and if updates are available, it
launches separate exe to copy files.

Before launching new process(exe), I am impersonating admin user as
main app is being launched by non-admin user.

User identity is changed after impersonation, but during update,
"Access is denied" win32Exception is being thrown when main code tries
to launch copier exe.

Impersonation is implemented using following win32 api.
<code>
string domainName = string.Empty;
try
{
// Get current windows identity
string currentWindowsI dentity = WindowsIdentity .GetCurrent().N ame;

domainName = currentWindowsI dentity.Substri ng(0,
currentWindowsI dentity.IndexOf ('\\'));

const int LOGON32_PROVIDE R_DEFAULT = 0;
//This parameter causes LogonUser to create a primary token.
const int LOGON32_LOGON_I NTERACTIVE = 2;
const int SecurityImperso nation = 2;
tokenHandle = IntPtr.Zero;
dupeTokenHandle = IntPtr.Zero;
// Call LogonUser to obtain a handle to an access token.
bool returnValue = LogonUser(_impe rsonationUserna me,
domainName,_imp ersonationPassw ord, LOGON32_LOGON_I NTERACTIVE,
LOGON32_PROVIDE R_DEFAULT,ref tokenHandle);

if (false == returnValue)
{
int ret = Marshal.GetLast Win32Error();
int errorCode = 0x5; //ERROR_ACCESS_DE NIED
throw new System.Componen tModel.Win32Exc eption(errorCod e);
}

// Check the identity.
bool retVal = DuplicateToken( tokenHandle, SecurityImperso nation, ref
dupeTokenHandle );
if (false == retVal)
{
CloseHandle(tok enHandle);
return;
}

// The token that is passed to the following constructor must
// be a primary token in order to use it for impersonation.
WindowsIdentity newId = new WindowsIdentity (dupeTokenHandl e);
_impersonatedUs er = newId.Impersona te();
}
catch(Exception ex)
{

}
</code>
I have enabled following security policies for non-admin user:

1) Replace a process level token.

2) Debug programs

3) Adjust memory quotas for a process

NOTE: 'Launching another exe' works fine, if no user impersonation is
used.

Any ideas, what might be wrong ?

~ViPuL

[Michael.Suarez]

I can't answer your question for you, but have you considered using
ClickOnce Deployment instead of your current method of checking for
updates? Then you wouldnt even need to bother with this whole issue.

[vipleo]

Well, we are still using .net 1.1 sp1. So ClickOnce is not a option...:(

[vipleo]

Following is the Detail Exception ia m getting:

Exception: System.Componen tModel.Win32Exc eption
Message: Access is denied
Source: System
at System.Diagnost ics.ProcessMana ger.OpenProcess (Int32 processId,
Int32 access, Boolean throwIfExited)
at System.Diagnost ics.NtProcessMa nager.GetModule Infos(Int32
processId)
at System.Diagnost ics.Process.get _Modules()
at System.Diagnost ics.Process.get _MainModule()

Help!!!!!!!!!!! !!
~ViPuL

[Willy Denoyette [MVP]]

"vipleo" <vn*****@gmail. com> wrote in message
news:11******** **************@ g47g2000cwa.goo glegroups.com.. .
| Following is the Detail Exception ia m getting:
|
| Exception: System.Componen tModel.Win32Exc eption
| Message: Access is denied
| Source: System
| at System.Diagnost ics.ProcessMana ger.OpenProcess (Int32 processId,
| Int32 access, Boolean throwIfExited)
| at System.Diagnost ics.NtProcessMa nager.GetModule Infos(Int32
| processId)
| at System.Diagnost ics.Process.get _Modules()
| at System.Diagnost ics.Process.get _MainModule()
|
| Help!!!!!!!!!!! !!
| ~ViPuL
|

And the code that throws this exception?

Willy.

[vipleo]

Here is the code I am using for launching another exe.

ProcessStartInf o proc = new ProcessStartInf o(CopierExecuta ble,
commandLine);
proc.WorkingDir ectory = ClientAppDirect ory;
proc.UseShellEx ecute = true; //I have also tried 'False'
Process.Start(p roc);

Here, CopierExecutabl e represents name of exe.

~ViPuL

[vipleo]

Here is complete function:

private void LaunchCopierExe cutable()
{
string filePath = Path.Combine(Cl ientAppDirector y, CopierExecutabl e);
if (!File.Exists(f ilePath))
{
throw new ApplicationExce ption("Invalid CopierExecutabl e config
setting: " + CopierExecutabl e);
}

string commandLine = "appdir='" + ClientAppDirect ory + "';upddir=' " +
ClientUpdatesDi rectory + "';bakdir=' " + ClientBackupDir ectory
+ "';procid=" + Process.GetCurr entProcess().Id + ";exe='" +
Process.GetCurr entProcess().Ma inModule.FileNa me + "';timeoutsecs= " +
MainAppShutdown Seconds.ToStrin g() + ";";

if (_returnParms.L ength > 0)
{
string sc = _returnParms.Su bstring(_return Parms.Length - 1, 1);
if( sc != ";") //add semi-colon
commandLine += "returnparm s='" + _returnParms + "';";
else
commandLine += "returnparm s='" + _returnParms + "'";
}

ProcessStartInf o proc = new ProcessStartInf o(CopierExecuta ble,
commandLine);
proc.WorkingDir ectory = ClientAppDirect ory;
proc.UseShellEx ecute = true;
Process.Start(p roc);
}

[Willy Denoyette [MVP]]

That looks much better.
Your problem is that you are trying to get some information from the current
process (MainModule) while impersonating. This is not possible because your
thread runs in an impersonated context, so you don't have access to the
process context.
What you should do is get this info before impersonating.

Willy.

"vipleo" <vn*****@gmail. com> wrote in message
news:11******** **************@ g44g2000cwa.goo glegroups.com.. .
| Here is complete function:
|
| private void LaunchCopierExe cutable()
| {
| string filePath = Path.Combine(Cl ientAppDirector y, CopierExecutabl e);
| if (!File.Exists(f ilePath))
| {
| throw new ApplicationExce ption("Invalid CopierExecutabl e config
| setting: " + CopierExecutabl e);
| }
|
| string commandLine = "appdir='" + ClientAppDirect ory + "';upddir=' " +
| ClientUpdatesDi rectory + "';bakdir=' " + ClientBackupDir ectory
| + "';procid=" + Process.GetCurr entProcess().Id + ";exe='" +
| Process.GetCurr entProcess().Ma inModule.FileNa me + "';timeoutsecs= " +
| MainAppShutdown Seconds.ToStrin g() + ";";
|
| if (_returnParms.L ength > 0)
| {
| string sc = _returnParms.Su bstring(_return Parms.Length - 1, 1);
| if( sc != ";") //add semi-colon
| commandLine += "returnparm s='" + _returnParms + "';";
| else
| commandLine += "returnparm s='" + _returnParms + "'";
| }
|
| ProcessStartInf o proc = new ProcessStartInf o(CopierExecuta ble,
| commandLine);
| proc.WorkingDir ectory = ClientAppDirect ory;
| proc.UseShellEx ecute = true;
| Process.Start(p roc);
| }
|

[vipleo]

Thanks for reply, willy.

But why this would be problem on win xp sp2 only.

Thanks,
~ViPuL

[Willy Denoyette [MVP]]

"vipleo" <vn*****@gmail. com> wrote in message
news:11******** **************@ g44g2000cwa.goo glegroups.com.. .
| Thanks for reply, willy.
|
| But why this would be problem on win xp sp2 only.
|
| Thanks,
| ~ViPuL
|

Different user privileges? Changes in SP2?

A process con only be 'opened' by the owner or by a caller with debug
provileges.
What I saw in your stack dump was that the caller did not have the requied
provileges to open the process:
<
Message: Access is denied
Source: System
at System.Diagnost ics.ProcessMana ger.OpenProcess (Int32 processId,
Int32 access, Boolean throwIfExited)

now I know why, the impersonating user is not the "owner" and he does not
have the required access privileges.

Willy.