Agfdhyk

I'm trying to execute a method from an object which is loaded from an assembly that is dynamically generated with CompilerResults.CompiledAssembly. However, I need this assembly to have restricted permissions because the methods it contains have an unexpected behavior.

I've searched a lot and the Microsoft docs suggest to use the security features provided by .NET Framework 4. This is one of the many sources I've read about sandboxing, which uses a different AppDomain with restricted permissions. Theoretically, I can create instances from the class within the assembly that is loaded in the restricted AppDomain and this instance will be considered a remote object.

To use the new object as a reference, a proxy is created internally when you try to access the object if the class extends the MarshalByRefObject class. In my case, the class which extends MarshalByRefObject is at the top of the hierarchy.

A simplified version of the code based on the link I've mentioned before is:

var permissionSet = ...;

var dllPath = ...;

// Create the AppDomainSetup

var info = new AppDomainSetup

{

    // Set the path to the assembly to load.

    ApplicationBase = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)

};

var strongName = assembly.Evidence.GetHostEvidence<StrongName>();

// Create the domain

var sandboxDomain = AppDomain.CreateDomain("RestrictedDomain", null, info, permissionSet, new StrongName { strongName });

var handle = Activator.CreateInstanceFrom(sandboxDomain, dllPath, "MyNamespace.MyClass");

var myLoadedTypeInstance = handle.Unwrap() as MyClass;

The code above works, the assembly is loaded in the AppDomain (only can do it referencing it's dll location, not it's name). But when I try to use a method from myLoadedTypeInstance with two serializable parameters I get an exception. The call is something like myLoadedTypeInstance.MyMethod(param1, param2) and the exception is:

"Method InitializeLifetimeService is not supported on this proxy, this can happen if the method is not marked with OperationContractAttribute or if the interface type is not marked with ServiceContractAttribute."

Some details:

• I don't know if it matters, but the first parameter is an objects which contains a property of type TChannel, created with ChannelFactory<T>.CreateChannel().


• It confuses me that the code fails when initializing lifetime service, but if I use RemotingServices.GetLifetimeService(myLoadedTypeInstance) as ILease I can access all the remote object's lifetime info.


• I've also tried to treat it as a remote object explicitly using Activator.GetObject() with the URL provided by RemotingServices.GetObjectUri(myLoadedTypeInstance), which is redundant because I end up creating two instances of the object. But it was a desperate move which had the same ending.


• I cannot debug this with VisualStudio as it's running in a separate process.