CodeAccessPermission.Deny Method

Definition

Namespace:

System.Security

Assembly:

System.Security.Permissions.dll

Source:

CodeAccessPermission.cs

Caution

This API is now deprecated.

Prevents callers higher in the call stack from using the code that calls this method to access the resource specified by the current instance.

public:
 virtual void Deny();

[System.Obsolete]
public void Deny ();

[<System.Obsolete>]
abstract member Deny : unit -> unit
override this.Deny : unit -> unit

Public Sub Deny ()

Implements

Deny()

Attributes

ObsoleteAttribute

Exceptions

SecurityException

There is already an active Deny() for the current frame.

Remarks

Important

The Deny method should be used only to protect resources from accidental access by fully trusted code. It should not be used to protect resources from intentional misuse by untrusted code. For example, if method A issues a Deny for a permission and then calls method B, method B can overtly override the Deny by issuing an Assert. The called method is always higher in the stack. Therefore, if method B tries to access a protected resource, the security system begins checking for permissions with it because method B is the immediate caller, and then walks down the stack to confirm that there is no Deny or PermitOnly lower in the stack. Method B, which is trying to access the resource, can stop the stack walk immediately by using the Assert method. In that case, the Deny placed on the stack by method A (the calling method) is never discovered.

This method prevents callers higher in the call stack from accessing the protected resource through the code that calls this method, even if those callers have been granted permission to access it. The call stack is typically represented as growing down, so that methods higher in the call stack call methods lower in the call stack.

Deny can limit the liability of the programmer or help prevent accidental security issues because it helps prevent the method that calls Deny from being used to access the resource protected by the denied permission. If a method calls Deny on a permission, and if a Demand for that permission is invoked by a caller lower in the call stack, that security check will fail when it reaches the Deny.

The call to Deny is effective until the calling code returns to its caller. Only one Deny can be active on a frame. An attempt to call Deny when an active Deny exists on the frame results in a SecurityException. Call RevertDeny or RevertAll to remove an active Deny. Deny is ignored for a permission not granted because a demand for that permission will not succeed.

Notes to Inheritors

You cannot override this method.