Export (0) Print
Expand All

CodeAccessPermission Class

Defines the underlying structure of all code access permissions.

Namespace:  System.Security
Assembly:  mscorlib (in mscorlib.dll)

[SerializableAttribute]
[ComVisibleAttribute(true)]
[SecurityPermissionAttribute(SecurityAction::InheritanceDemand, ControlEvidence = true, 
	ControlPolicy = true)]
public ref class CodeAccessPermission abstract : IPermission, 
	ISecurityEncodable, IStackWalk

Code access permissions use a stack walk to ensure that all callers of the code have been granted a permission. If a permission object is nullptr, it is handled the same as a permission object with the state PermissionState::None.

The call stack is typically represented as growing down, so that methods higher in the call stack call methods lower in the call stack.

Inheritors of the CodeAccessPermission class must be granted full trust to function correctly as permissions extending the security infrastructure. To determine that the inheritors are fully trusted, CodeAccessPermission issues an InheritanceDemand for ControlEvidence = true and ControlPolicy = true.

For more information on inheritance demands, see Inheritance Demands.

Notes to Inheritors:

When you inherit from CodeAccessPermission, you must also implement the IUnrestrictedPermission interface.

The following CodeAccessPermission members must be overridden: Copy, Intersect, IsSubsetOf, ToXml, FromXml, and Union.

You must also define a constructor that takes a PermissionState as its only parameter.

You must apply the SerializableAttribute attribute to a class that inherits from CodeAccessPermission.

The following code example shows a permission derived from the CodeAccessPermission class.

//#define debug 
// This custom permission is intended only for the purposes of illustration. 
// The following code shows how to create a custom permission that inherits 
// from CodeAccessPermission. The code implements all required overrides. 
// A wildcard character ('*') is implemented for the Name property. 

using namespace System;
using namespace System::Security;
using namespace System::Security::Permissions;
using namespace System::IO;
using namespace System::Security::Policy;
using namespace System::Collections;
using namespace System::Text;

[assembly:System::Reflection::AssemblyKeyFile("Key.snk")];
[assembly:System::Security::AllowPartiallyTrustedCallersAttribute];

[Serializable]
public ref class NameIdPermission: public CodeAccessPermission, public IUnrestrictedPermission
{
private:
   String^ m_Name;
   bool m_Unrestricted;

public:
   NameIdPermission( String^ name )
   {
      m_Name = name;
   }

   NameIdPermission( PermissionState state )
   {
      if ( state == PermissionState::None )
      {
         m_Name = "";
      }
      else if ( state == PermissionState::Unrestricted )
      {
         throw gcnew ArgumentException( "Unrestricted state is not allowed for identity permissions." );
      }
      else
      {
         throw gcnew ArgumentException( "Invalid permission state." );
      }
   }

   property String^ Name 
   {
      String^ get()
      {
         return m_Name;
      }
      void set( String^ value )
      {
         m_Name = value;
      }
   }

public:
   virtual IPermission^ Copy() override
   {
      String^ name = m_Name;
      return gcnew NameIdPermission( name );
   }

public:
   virtual bool IsUnrestricted()
   {
      // Always false, unrestricted state is not allowed. 
      return m_Unrestricted;
   }

private:
   bool VerifyType( IPermission^ target )
   {
      return dynamic_cast<NameIdPermission^>(target) != nullptr;
   }

public:
   virtual bool IsSubsetOf( IPermission^ target ) override
   {
#if ( debug ) 
      Console::WriteLine( "************* Entering IsSubsetOf *********************" );
#endif

      if ( target == nullptr )
      {
         Console::WriteLine( "IsSubsetOf: target == null" );
         return false;
      }

#if ( debug ) 
      Console::WriteLine( "This is = {0}", ((NameIdPermission)this).Name );
      Console::WriteLine( "Target is {0}", ((NameIdPermission)target).m_Name );
#endif

      try
      {
         NameIdPermission^ operand = dynamic_cast<NameIdPermission^>(target);

         // The following check for unrestricted permission is only included as an example for 
         // permissions that allow the unrestricted state. It is of no value for this permission. 
         if ( true == operand->m_Unrestricted )
         {
            return true;
         }
         else if ( true == this->m_Unrestricted )
         {
            return false;
         }

         if ( this->m_Name != nullptr )
         {
            if ( operand->m_Name == nullptr )
            {
               return false;
            }
            if ( this->m_Name->Equals( "" ) )
            {
               return true;
            }
         }

         if ( this->m_Name->Equals( operand->m_Name ) )
         {
            return true;
         }
         else
         {
            // Check for wild card character '*'. 
            int i = operand->m_Name->LastIndexOf( "*" );

            if ( i > 0 )
            {
               String^ prefix = operand->m_Name->Substring( 0, i );
               if ( this->m_Name->StartsWith( prefix ) )
               {
                  return true;
               }
            }
         }
         return false;
      }
      catch ( InvalidCastException^ ) 
      {
         throw gcnew ArgumentException( String::Format( "Argument_WrongType", this->GetType()->FullName ) );
      }
   }

public:
   virtual IPermission^ Intersect( IPermission^ target ) override
   {
      Console::WriteLine( "************* Entering Intersect *********************" );
      if ( target == nullptr )
      {
         return nullptr;
      }

#if ( debug ) 
      Console::WriteLine( "This is = {0}", ((NameIdPermission)this).Name );
      Console::WriteLine( "Target is {0}", ((NameIdPermission)target).m_Name );
#endif 

      if (  !VerifyType( target ) )
      {
         throw gcnew ArgumentException( String::Format( "Argument is wrong type.", this->GetType()->FullName ) );
      }

      NameIdPermission^ operand = dynamic_cast<NameIdPermission^>(target);

      if ( operand->IsSubsetOf( this ) )
      {
         return operand->Copy();
      }
      else if ( this->IsSubsetOf( operand ) )
      {
         return this->Copy();
      }
      else
      {
         return nullptr;
      }
   }

public:
   virtual IPermission^ Union( IPermission^ target ) override
   {
#if ( debug ) 
      Console::WriteLine( "************* Entering Union *********************" );
#endif 

      if ( target == nullptr )
      {
         return this;
      }

#if ( debug ) 
      Console::WriteLine( "This is = {0}", ((NameIdPermission)this).Name );
      Console::WriteLine( "Target is {0}", ((NameIdPermission)target).m_Name );
#endif 

      if (  !VerifyType( target ) )
      {
         throw gcnew ArgumentException( String::Format( "Argument_WrongType", this->GetType()->FullName ) );
      }

      NameIdPermission^ operand = dynamic_cast<NameIdPermission^>(target);

      if ( operand->IsSubsetOf( this ) )
      {
         return this->Copy();
      }
      else if ( this->IsSubsetOf( operand ) )
      {
         return operand->Copy();
      }
      else
      {
         return nullptr;
      }
   }

public:
   virtual void FromXml( SecurityElement^ e ) override
   {
      // The following code for unrestricted permission is only included as an example for 
      // permissions that allow the unrestricted state. It is of no value for this permission.
      String^ elUnrestricted = e->Attribute("Unrestricted");
      if ( nullptr != elUnrestricted )
      {
         m_Unrestricted = Boolean::Parse( elUnrestricted );
         return;
      }

      String^ elName = e->Attribute("Name");
      m_Name = elName == nullptr ? nullptr : elName;
   }

public:
   virtual SecurityElement^ ToXml() override
   {
      // Use the SecurityElement class to encode the permission to XML.
      SecurityElement^ esd = gcnew SecurityElement( "IPermission" );
      String^ name = NameIdPermission::typeid->AssemblyQualifiedName;
      esd->AddAttribute( "class", name );
      esd->AddAttribute( "version", "1.0" );

      // The following code for unrestricted permission is only included as an example for 
      // permissions that allow the unrestricted state. It is of no value for this permission. 
      if ( m_Unrestricted )
      {
         esd->AddAttribute( "Unrestricted", true.ToString() );
      }

      if ( m_Name != nullptr )
      {
         esd->AddAttribute( "Name", m_Name );
      }

      return esd;
   }
};

System::Object
  System.Security::CodeAccessPermission
    System.Configuration::ConfigurationPermission
    System.Data.Common::DBDataPermission
    System.Data.OracleClient::OraclePermission
    System.Drawing.Printing::PrintingPermission
    System.Messaging::MessageQueuePermission
    System.Net::DnsPermission
    System.Net.Mail::SmtpPermission
    System.Net.NetworkInformation::NetworkInformationPermission
    System.Net.PeerToPeer.Collaboration::PeerCollaborationPermission
    System.Net.PeerToPeer::PnrpPermission
    System.Net::SocketPermission
    System.Net::WebPermission
    System.Security.Permissions::DataProtectionPermission
    System.Security.Permissions::EnvironmentPermission
    System.Security.Permissions::FileDialogPermission
    System.Security.Permissions::FileIOPermission
    System.Security.Permissions::GacIdentityPermission
    System.Security.Permissions::IsolatedStoragePermission
    System.Security.Permissions::KeyContainerPermission
    System.Security.Permissions::MediaPermission
    System.Security.Permissions::PublisherIdentityPermission
    System.Security.Permissions::ReflectionPermission
    System.Security.Permissions::RegistryPermission
    System.Security.Permissions::ResourcePermissionBase
    System.Security.Permissions::SecurityPermission
    System.Security.Permissions::SiteIdentityPermission
    System.Security.Permissions::StorePermission
    System.Security.Permissions::StrongNameIdentityPermission
    System.Security.Permissions::UIPermission
    System.Security.Permissions::UrlIdentityPermission
    System.Security.Permissions::WebBrowserPermission
    System.Security.Permissions::ZoneIdentityPermission
    System.Transactions::DistributedTransactionPermission
    System.Web::AspNetHostingPermission

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

Community Additions

ADD
Show:
© 2014 Microsoft