Programming .NET Security

Name

IStackWalk

Synopsis

public interface IStackWalk {
// Public Instance Methods
   public void Assert(  );
   public void Demand(  );
   public void Deny(  );
   public void PermitOnly(  );
}

Permission classes that use stack walks to resolve security demands implement the IStackWalk interface. These include the PermissionSet class, as well as the CodeAccessPermission class, from which all standard code-access and identity permissions inherit.

IStackWalk defines the Demand( ) method, which duplicates the method of the same name defined in the IPermission interface. However, the IStackWalk.Demand( ) method initiates a stack-walk-based security demand, whereas IPermission.Demand( ) is not intended to use the call stack to resolve security demands. The Assert( ), Deny( ), and PermitOnly( ) methods annotate the call stack frame of the code from which they are executed, and affect the stack walk process initiated by a Demand( ) call.

Assert( ) allows code to vouch for the permissions of the callers above it on the call stack. During a stack walk, if a demanded permission matches, or is a subset of, the asserted permission, the stack walk terminates successfully without evaluating further stack frames. If the asserted permissions provide only a partial match of those demanded, the stack walk continues but only for the remaining unasserted permissions. Code must have been granted a permission in order to assert it, and the code must have the permission to assert defined by the System.Security.Permissions.SecurityPermission ...