What is the correct way to set up the EventWaitHandleSecurity in the following sample that uses EventWaitHandle to ensure a single instance application?
/// <summary>
/// The method either:
/// 1) acquires mutex and starts listing if anyone tries to get the same mutex,
/// or
/// 2) notifies the instance that actually owns the mutex
/// </summary>
/// <param name="isSystemWide">
/// true if mutex is system wide (can belong to any user of the system),
/// false if there could be one mutex per active user
/// </param>
/// <param name="instanceName">The name of the mutex</param>
/// <param name="callback">Callback to be raised after the mutex is acquired
/// on every time another instance tries (and fails) to acquire the mutex</param>
/// <returns>
/// true if mutex is acquired (and event is subsribed),
/// false otherwise (and the mutex owner is notified)
/// </returns>
public static bool TryListenOrNotify(bool isSystemWide, string instanceName, Action callback)
{
var name = (isSystemWide ? "Global" : "Local") + "\\" + instanceName;
var securityIdentifier = new SecurityIdentifier(WellKnownSidType.WorldSid, (SecurityIdentifier)null);
var rule = new EventWaitHandleAccessRule(securityIdentifier, EventWaitHandleRights.FullControl, AccessControlType.Allow);
var waitHandleSecurity = new EventWaitHandleSecurity();
waitHandleSecurity.AddAccessRule(rule);
bool createdNew;
var eventWaitHandle = new EventWaitHandle(false, EventResetMode.AutoReset, name, out createdNew, waitHandleSecurity);
if(createdNew)
{
// mutex not acquired
var thread = new Thread(() =>
{
using(eventWaitHandle)
{
// listening for notifications
while(eventWaitHandle.WaitOne())
{
callback();
}
}
});
thread.IsBackground = true;
thread.Start();
return true;
}
else
{
// mutex is not acquired
using(eventWaitHandle)
{
// notifying the mutex owner
eventWaitHandle.Set();
}
return false;
}
}
In particular, I don't like to blindly grant all access to everyone. But I can't figure it out what is the default security settings and what is the least privilege set in that case?
Thank you.
