CA2123：覆寫連結要求應該與基底相同

型別名稱	OverrideLinkDemandsShouldBeIdenticalToBase
CheckId	CA2123
分類	Microsoft.Security
中斷變更	中斷

原因

公用型別中之公用或保護的方法會覆寫方法或實作介面，而且沒有與介面或虛擬方法相同的連結要求。

規則描述

這項規則會使方法符合它的基底方法，即另一個型別中的介面或虛擬方法，然後比較每個方法上的連結要求。 如果方法或基底方法具有連結要求，但另一個方法卻沒有，將會報告違規。

如果違反這項規則，則惡意呼叫端只需呼叫不安全的方法，就可以略過連結要求。

如何修正違規

若要修正此規則的違規，請將同一個連結要求套用至覆寫方法或實作。 如果這樣不可能，請以完整要求標記方法，或是完全移除屬性。

隱藏警告的時機

請勿隱藏此規則的警告。

範例

下列範例會顯示這項規則的各種違規。

using System.Security;
using System.Security.Permissions;
using System;

namespace SecurityRulesLibrary
{
   public interface ITestOverrides
   {  
      [EnvironmentPermissionAttribute(SecurityAction.LinkDemand, Unrestricted=true)]
      Object GetFormat(Type formatType);
   }

   public class OverridesAndSecurity : ITestOverrides
   {
      // Rule violation: The interface has security, and this implementation does not.
      object ITestOverrides.GetFormat(Type formatType)
      {
         return (formatType == typeof(OverridesAndSecurity) ? this : null);
      }

      // These two methods are overridden by DerivedClass and DoublyDerivedClass.
      [EnvironmentPermissionAttribute(SecurityAction.LinkDemand, Unrestricted=true)]
      public virtual void DoSomething()
      {
         Console.WriteLine("Doing something.");
      }

      public virtual void DoSomethingElse()
      {
         Console.WriteLine("Doing some other thing.");
      }
   }

   public class DerivedClass : OverridesAndSecurity, ITestOverrides
   {
      //  Rule violation: The interface has security, and this implementation does not.
      public object GetFormat(Type formatType)
      {
         return (formatType == typeof(OverridesAndSecurity) ? this : null);
      }

      // Rule violation: This does not have security, but the base class version does.
      public override void DoSomething()
      {
         Console.WriteLine("Doing some derived thing.");
      }

      // Rule violation: This has security, but the base class version does not.
      [EnvironmentPermissionAttribute(SecurityAction.LinkDemand, Unrestricted=true)]
      public override void DoSomethingElse()
      {
         Console.WriteLine("Doing some other derived thing.");
      }
   }

   public class DoublyDerivedClass : DerivedClass
   {
      // The OverridesAndSecurity version of this method does not have security. 
      // Base class DerivedClass's version does. 
      // The DoublyDerivedClass version does not violate the rule, but the 
      // DerivedClass version does violate the rule.
      public override void DoSomethingElse()
      {
         Console.WriteLine("Doing some other derived thing.");
      }
   }
}

請參閱

概念

安全程式碼撰寫方針

連結要求