Limiting code in method to only call members in same class

Question

Is there a way that I can limit the the calls made in one method in my class so only methods and properties on the enclosing class (also inherited) can be called. I'm using c# (.NET 4.5). This would be used as a code security feature in our application framework.

Answer 1

You should look in to AppDomain sandboxing. It allows you to load plugins in to a separate AppDomain and assign execution permissions at a very granular level.

Running a runtime compiled C# script in a sandbox AppDomain and http://msdn.microsoft.com/en-us/library/bb763046(v=vs.110).aspx should give you an idea of how to proceed.

Answer 2

From How to: Run Partially Trusted Code in a Sandbox

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Security;
using System.Security.Policy;
using System.Security.Permissions;
using System.Reflection;
using System.Runtime.Remoting;

// The Sandboxer class needs to derive from MarshalByRefObject
// so that we can create it in another AppDomain and refer to
// it from the default AppDomain.
class Sandboxer : MarshalByRefObject
{
    const string pathToUntrusted = @"..\..\..\UntrustedCode\bin\Debug";
    const string untrustedAssembly = "UntrustedCode";
    const string untrustedClass = "UntrustedCode.UntrustedClass";
    const string entryPoint = "IsFibonacci";
    private static Object[] parameters = { 45 };

    static void Main()
    {
        // Setting the AppDomainSetup. It is very important to set the
        // ApplicationBase to a folder other than the one in which
        // the sandboxer resides.
        AppDomainSetup adSetup = new AppDomainSetup();
        adSetup.ApplicationBase = Path.GetFullPath(pathToUntrusted);

        // Setting the permissions for the AppDomain. We give the permission
        // to execute and to read/discover the location where the untrusted
        // code is loaded.
        PermissionSet permSet = new PermissionSet(PermissionState.None);
        permSet.AddPermission(
            new SecurityPermission(SecurityPermissionFlag.Execution));

        // We want the sandboxer assembly's strong name, so that we can add
        // it to the full trust list.
        StrongName fullTrustAssembly =
            typeof(Sandboxer).Assembly.Evidence.GetHostEvidence<StrongName>();

        // Now we have everything we need to create the AppDomain so,
        // let's create it.
        AppDomain newDomain = AppDomain.CreateDomain(
                "Sandbox",
                null,
                adSetup,
                permSet,
                fullTrustAssembly);

        // Use CreateInstanceFrom to load an instance of the Sandboxer class
        // into the new AppDomain. 
        ObjectHandle handle = Activator.CreateInstanceFrom(
            newDomain,
            typeof(Sandboxer).Assembly.ManifestModule.FullyQualifiedName,
            typeof(Sandboxer).FullName);

        // Unwrap the new domain instance into a reference in this domain and
        // use it to execute the untrusted code.
        Sandboxer newDomainInstance = (Sandboxer)handle.Unwrap();
        newDomainInstance.ExecuteUntrustedCode(
            untrustedAssembly,
            untrustedClass,
            entryPoint,
            parameters);
    }

    public void ExecuteUntrustedCode(
            string assemblyName,
            string typeName,
            string entryPoint,
            object[] parameters)
    {
        // Load the MethodInfo for a method in the new Assembly. This might be
        // a method you know, or you can use Assembly.EntryPoint to get to the
        // main function in an executable.
        MethodInfo target =
            Assembly.Load(assemblyName)
               .GetType(typeName)
               .GetMethod(entryPoint);

        try
        {
            //Now invoke the method.
            bool retVal = (bool)target.Invoke(null, parameters);
        }
        catch (Exception ex)
        {
            // When we print informations from a SecurityException extra
            // information can be printed if we are  calling it with a
            // full-trust stack.
            (new PermissionSet(PermissionState.Unrestricted)).Assert();
            Console.WriteLine(
                "SecurityException caught:\n{0}",
                ex);
            CodeAccessPermission.RevertAssert();
            Console.ReadLine();
        }
    }
}