private void ToggleState(bool enable)
{
int error = 0;
// All privilege operations must take place on the same thread
if (!this.currentThread.Equals(Thread.CurrentThread))
{
throw new InvalidOperationException("Operation must take place on the thread that created the object");
}
// This privilege was already altered and needs to be reverted before it can be altered again
if (this.NeedToRevert)
{
throw new InvalidOperationException("Must revert the privilege prior to attempting this operation");
}
// Need to make this block of code non-interruptible so that it would preserve
// consistency of thread oken state even in the face of catastrophic exceptions
try
{
// The payload is entirely in the finally block
// This is how we ensure that the code will not be
// interrupted by catastrophic exceptions
}
finally
{
try
{
// Retrieve TLS state
this.tlsContents = Thread.GetData(tlsSlot) as TlsContents;
if (this.tlsContents == null)
{
this.tlsContents = new TlsContents();
Thread.SetData(tlsSlot, this.tlsContents);
}
else
{
this.tlsContents.IncrementReferenceCount();
}
NativeMethods.TOKEN_PRIVILEGE newState = new NativeMethods.TOKEN_PRIVILEGE();
newState.PrivilegeCount = 1;
newState.Privilege.Luid = this.luid;
newState.Privilege.Attributes = enable ? NativeMethods.SE_PRIVILEGE_ENABLED : NativeMethods.SE_PRIVILEGE_DISABLED;
NativeMethods.TOKEN_PRIVILEGE previousState = new NativeMethods.TOKEN_PRIVILEGE();
uint previousSize = 0;
// Place the new privilege on the thread token and remember the previous state.
if (false == NativeMethods.AdjustTokenPrivileges(
this.tlsContents.ThreadHandle,
false,
ref newState,
(uint)Marshal.SizeOf(previousState),
ref previousState,
ref previousSize))
{
error = Marshal.GetLastWin32Error();
}
else if (NativeMethods.ERROR_NOT_ALL_ASSIGNED == Marshal.GetLastWin32Error())
{
error = NativeMethods.ERROR_NOT_ALL_ASSIGNED;
}
else
{
// This is the initial state that revert will have to go back to
this.initialState = ((previousState.Privilege.Attributes & NativeMethods.SE_PRIVILEGE_ENABLED) != 0);
// Remember whether state has changed at all
this.stateWasChanged = (this.initialState != enable);
// If we had to impersonate, or if the privilege state changed we'll need to revert
this.needToRevert = this.tlsContents.IsImpersonating || this.stateWasChanged;
}
}
finally
{
if (!this.needToRevert)
{
this.Reset();
}
}
}
if (error == NativeMethods.ERROR_NOT_ALL_ASSIGNED)
{
throw new PrivilegeNotHeldException(privileges[this.luid] as string);
}
if (error == NativeMethods.ERROR_NOT_ENOUGH_MEMORY)
{
throw new OutOfMemoryException();
}
else if (error == NativeMethods.ERROR_ACCESS_DENIED ||
error == NativeMethods.ERROR_CANT_OPEN_ANONYMOUS)
{
throw new UnauthorizedAccessException("The caller does not have the right to change the privilege");
}
else if (error != 0)
{
throw new Win32Exception(error);
}
}
public void Revert()
{
int error = 0;
// All privilege operations must take place on the same thread
if (!this.currentThread.Equals(Thread.CurrentThread))
{
throw new InvalidOperationException("Operation must take place on the thread that created the object");
}
if (!this.NeedToRevert)
{
return;
}
// This code must be eagerly prepared and non-interruptible.
try
{
// The payload is entirely in the finally block
// This is how we ensure that the code will not be
// interrupted by catastrophic exceptions
}
finally
{
bool success = true;
try
{
// Only call AdjustTokenPrivileges if we're not going to be reverting to self,
// on this Revert, since doing the latter obliterates the thread token anyway
if (this.stateWasChanged &&
(this.tlsContents.ReferenceCountValue > 1 ||
!this.tlsContents.IsImpersonating))
{
NativeMethods.TOKEN_PRIVILEGE newState = new NativeMethods.TOKEN_PRIVILEGE();
newState.PrivilegeCount = 1;
newState.Privilege.Luid = this.luid;
newState.Privilege.Attributes = (this.initialState ? NativeMethods.SE_PRIVILEGE_ENABLED : NativeMethods.SE_PRIVILEGE_DISABLED);
NativeMethods.TOKEN_PRIVILEGE previousState = new NativeMethods.TOKEN_PRIVILEGE();
uint previousSize = 0;
if (false == NativeMethods.AdjustTokenPrivileges(
this.tlsContents.ThreadHandle,
false,
ref newState,
(uint)Marshal.SizeOf(previousState),
ref previousState,
ref previousSize))
{
error = Marshal.GetLastWin32Error();
success = false;
}
}
}
finally
{
if (success)
{
this.Reset();
}
}
}
if (error == NativeMethods.ERROR_NOT_ENOUGH_MEMORY)
{
throw new OutOfMemoryException();
}
else if (error == NativeMethods.ERROR_ACCESS_DENIED)
{
throw new UnauthorizedAccessException("Caller does not have the permission to change the privilege");
}
else if (error != 0)
{
throw new Win32Exception(error);
}
}
