CodeAccessPermission 类

定义

定义所有代码访问权限的基础结构。Defines the underlying structure of all code access permissions.

public ref class CodeAccessPermission abstract : System::Security::IPermission, System::Security::IStackWalk
[System.Runtime.InteropServices.ComVisible(true)]
[System.Serializable]
public abstract class CodeAccessPermission : System.Security.IPermission, System.Security.IStackWalk
type CodeAccessPermission = class
    interface IPermission
    interface ISecurityEncodable
    interface IStackWalk
Public MustInherit Class CodeAccessPermission
Implements IPermission, IStackWalk
继承
CodeAccessPermission
派生
属性
实现

示例

下面的代码示例演示一个派生自 CodeAccessPermission 类的权限。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;
   }
};
//#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 System;
using System.Security;
using System.Security.Permissions;
using System.IO;
using System.Security.Policy;
using System.Collections;
using System.Text;

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

namespace MyPermission
{
    [Serializable()] sealed public class   NameIdPermission : CodeAccessPermission, IUnrestrictedPermission
    {
        private String m_Name;
        private bool m_Unrestricted;

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

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

        public String Name
        {
            set{m_Name = value;}
            get{ return m_Name;}
        }
        public override IPermission Copy()
        {
            string name = m_Name;
            return new  NameIdPermission( name );
        }
        public bool IsUnrestricted()
        {
            // Always false, unrestricted state is not allowed.
            return m_Unrestricted;
        }

        private bool VerifyType(IPermission target)
        {
            return (target is  NameIdPermission);
        }
        public override bool IsSubsetOf(IPermission target)
        {
#if(debug)
            Console.WriteLine ("************* Entering IsSubsetOf *********************");
#endif
            if (target == null)
            {
                Console.WriteLine ("IsSubsetOf: target == null");
                return false;
            }
#if(debug)

            Console.WriteLine ("This is = " + (( NameIdPermission)this).Name);
            Console.WriteLine ("Target is " + (( NameIdPermission)target).m_Name);
#endif
            try
            {
                 NameIdPermission operand = ( 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 != null)
                {
                    if (operand.m_Name == null) return false;

                    if (this.m_Name == "") 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 new ArgumentException (String.Format ("Argument_WrongType", this.GetType ().FullName));
            }
        }
        public override IPermission Intersect(IPermission target)
        {
            Console.WriteLine ("************* Entering Intersect *********************");
            if (target == null)
            {
                return null;
            }
#if(debug)
            Console.WriteLine ("This is = " + (( NameIdPermission)this).Name);
            Console.WriteLine ("Target is " + (( NameIdPermission)target).m_Name);
#endif
            if (!VerifyType(target))
            {
                throw new ArgumentException (String.Format ("Argument is wrong type.", this.GetType ().FullName));
            }

             NameIdPermission operand = ( NameIdPermission)target;

            if (operand.IsSubsetOf (this)) return operand.Copy ();
            else if (this.IsSubsetOf (operand)) return this.Copy ();
            else
                return null;
        }

        public override IPermission Union(IPermission target)
        {
#if(debug)
            Console.WriteLine ("************* Entering Union *********************");
#endif
            if (target == null)
            {
                return this;
            }
#if(debug)
            Console.WriteLine ("This is = " + (( NameIdPermission)this).Name);
            Console.WriteLine ("Target is " + (( NameIdPermission)target).m_Name);
#endif
            if (!VerifyType(target))
            {
                throw new ArgumentException (String.Format ("Argument_WrongType", this.GetType ().FullName));
            }

             NameIdPermission operand = ( NameIdPermission)target;

            if (operand.IsSubsetOf (this)) return this.Copy ();
            else if (this.IsSubsetOf (operand)) return operand.Copy ();
            else
                return null;
        }
        
        
        
        
       public override void FromXml(SecurityElement e)
        {
            // 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 (null != elUnrestricted)
            {
                m_Unrestricted = bool.Parse(elUnrestricted);
                return;
            }

            String elName = e.Attribute( "Name" );
            m_Name = elName == null ? null : elName;
        }
        public override SecurityElement ToXml()
        {
            // Use the SecurityElement class to encode the permission to XML.
            SecurityElement esd = new SecurityElement("IPermission");
            String name = typeof( NameIdPermission).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 != null) esd.AddAttribute( "Name", m_Name );
            return esd;
        }
     }
}
' 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.
Imports System.Security
Imports System.Security.Permissions
Imports System.IO
Imports System.Security.Policy
Imports System.Collections

<assembly: System.Reflection.AssemblyKeyFile("Key.snk")>

<assembly: System.Security.AllowPartiallyTrustedCallersAttribute()>
Namespace MyPermission

    <Serializable()> _
                   Public NotInheritable Class NameIdPermission
        Inherits CodeAccessPermission
        Implements IUnrestrictedPermission
        Private m_Name As String
        Private m_Unrestricted As Boolean


        Public Sub New(ByVal name As String)
            m_name = name
        End Sub


        Public Sub New(ByVal state As PermissionState)
            If state = PermissionState.None Then
                m_name = ""
            ElseIf state = PermissionState.Unrestricted Then
                Throw New ArgumentException("Unrestricted state is not allowed for identity permissions.")
            Else
                Throw New ArgumentException("Invalid permission state.")
            End If
        End Sub

        Public Property Name() As String
            Get
                Return m_name
            End Get
            Set(ByVal Value As String)
                m_name = Value
            End Set
        End Property

        Public Overrides Function Copy() As IPermission
            Dim name As String
            name = m_name
            Return New NameIdPermission(name)
        End Function 'Copy

        Public Function IsUnrestricted() As Boolean Implements IUnrestrictedPermission.IsUnrestricted
            ' Always false, unrestricted state is not allowed.
            Return m_Unrestricted
        End Function
        Private Function VerifyType(ByVal target As IPermission) As Boolean
            Return TypeOf target Is NameIdPermission
        End Function 'VerifyType

        Public Overrides Function IsSubsetOf(ByVal target As IPermission) As Boolean

#If (Debug) Then

            Console.WriteLine("************* Entering IsSubsetOf *********************")
#End If
            If target Is Nothing Then
                Console.WriteLine("IsSubsetOf: target == null")
                Return False
            End If
#If (Debug) Then
            Console.WriteLine(("This is = " + CType(Me, NameIdPermission).Name))
            Console.WriteLine(("Target is " + CType(target, NameIdPermission).m_name))
#End If
            Try
                Dim operand As NameIdPermission = CType(target, NameIdPermission)

                ' 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 Then
                    Return True
                ElseIf True = Me.m_Unrestricted Then
                    Return False
                End If

                If Not (Me.m_name Is Nothing) Then
                    If operand.m_name Is Nothing Then
                        Return False
                    End If
                    If Me.m_name = "" Then
                        Return True
                    End If
                End If
                If Me.m_name.Equals(operand.m_name) Then
                    Return True
                Else
                    ' Check for wild card character '*'.
                    Dim i As Integer = operand.m_name.LastIndexOf("*")

                    If i > 0 Then
                        Dim prefix As String = operand.m_name.Substring(0, i)

                        If Me.m_name.StartsWith(prefix) Then
                            Return True
                        End If
                    End If
                End If

                Return False
            Catch
                Throw New ArgumentException(String.Format("Argument_WrongType", Me.GetType().FullName))
            End Try
        End Function

        Public Overrides Function Intersect(ByVal target As IPermission) As IPermission
            Console.WriteLine("************* Entering Intersect *********************")
            If target Is Nothing Then
                Return Nothing
            End If
#If (Debug) Then

            Console.WriteLine(("This is = " + CType(Me, NameIdPermission).Name))
            Console.WriteLine(("Target is " + CType(target, NameIdPermission).m_name))
#End If
            If Not VerifyType(target) Then
                Throw New ArgumentException(String.Format("Argument is wrong type.", Me.GetType().FullName))
            End If

            Dim operand As NameIdPermission = CType(target, NameIdPermission)

            If operand.IsSubsetOf(Me) Then
                Return operand.Copy()
            ElseIf Me.IsSubsetOf(operand) Then
                Return Me.Copy()
            Else
                Return Nothing
            End If
        End Function 'Intersect

        Public Overrides Function Union(ByVal target As IPermission) As IPermission
#If (Debug) Then

            Console.WriteLine("************* Entering Union *********************")
#End If
            If target Is Nothing Then
                Return Me
            End If
#If (Debug) Then
            Console.WriteLine(("This is = " + CType(Me, NameIdPermission).Name))
            Console.WriteLine(("Target is " + CType(target, NameIdPermission).m_name))
#End If
            If Not VerifyType(target) Then
                Throw New ArgumentException(String.Format("Argument_WrongType", Me.GetType().FullName))
            End If

            Dim operand As NameIdPermission = CType(target, NameIdPermission)

            If operand.IsSubsetOf(Me) Then
                Return Me.Copy()
            ElseIf Me.IsSubsetOf(operand) Then
                Return operand.Copy()
            Else
                Return Nothing
            End If
        End Function 'Union

        Public Overrides Sub FromXml(ByVal e As SecurityElement)
            ' 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.
            Dim elUnrestricted As String = e.Attribute("Unrestricted")
            If Nothing <> elUnrestricted Then
                m_Unrestricted = Boolean.Parse(elUnrestricted)
                Return
            End If

            Dim elName As String = e.Attribute("Name")
            m_name = IIf(elName Is Nothing, Nothing, elName)
        End Sub

        Public Overrides Function ToXml() As SecurityElement
            ' Use the SecurityElement class to encode the permission to XML.
            Dim esd As New SecurityElement("IPermission")

            Dim name As String = GetType(NameIdPermission).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 Then
                esd.AddAttribute("Unrestricted", True.ToString())
            End If
            If Not (m_Name Is Nothing) Then
                esd.AddAttribute("Name", m_Name)
            End If
            Return esd
        End Function 'ToXml
    End Class
End Namespace

注解

代码访问权限使用堆栈审核来确保已为代码的所有调用方授予了权限。Code access permissions use a stack walk to ensure that all callers of the code have been granted a permission. 如果 null权限对象,则会将其处理方式与状态为 PermissionState.None的权限对象相同。If a permission object is null, it is handled the same as a permission object with the state PermissionState.None.

调用堆栈通常表示为向下增长,因此调用堆栈中较高位置的方法调用堆栈中较低的调用方法。The call stack is typically represented as growing down, so that methods higher in the call stack call methods lower in the call stack.

必须将 CodeAccessPermission 类的继承者授予完全信任,才能作为权限扩展安全基础结构。Inheritors of the CodeAccessPermission class must be granted full trust to function correctly as permissions extending the security infrastructure. 若要确定继承者是完全受信任的,CodeAccessPermission ControlEvidence = trueControlPolicy = true发出 InheritanceDemandTo determine that the inheritors are fully trusted, CodeAccessPermission issues an InheritanceDemand for ControlEvidence = true and ControlPolicy = true.

实施者说明

CodeAccessPermission继承时,还必须实现 IUnrestrictedPermission 接口。When you inherit from CodeAccessPermission, you must also implement the IUnrestrictedPermission interface.

必须重写以下 CodeAccessPermission 成员: Copy()Intersect(IPermission)IsSubsetOf(IPermission)ToXml()FromXml(SecurityElement)Union(IPermission)The following CodeAccessPermission members must be overridden: Copy(), Intersect(IPermission), IsSubsetOf(IPermission), ToXml(), FromXml(SecurityElement), and Union(IPermission).

还必须定义一个采用 PermissionState 作为其唯一参数的构造函数。You must also define a constructor that takes a PermissionState as its only parameter.

必须将 SerializableAttribute 特性应用到继承自 CodeAccessPermission的类。You must apply the SerializableAttribute attribute to a class that inherits from CodeAccessPermission.

构造函数

CodeAccessPermission()

初始化 CodeAccessPermission 类的新实例。Initializes a new instance of the CodeAccessPermission class.

方法

Assert()

声明调用代码能够通过调用此方法的代码,访问受权限请求保护的资源,即使未对堆栈中处于较高位置的调用方授予访问该资源的权限。Declares that the calling code can access the resource protected by a permission demand through the code that calls this method, even if callers higher in the stack have not been granted permission to access the resource. 使用 Assert() 会引起安全问题。Using Assert() can create security issues.

Copy()

由派生类实现时,创建并返回当前权限对象的相同副本。When implemented by a derived class, creates and returns an identical copy of the current permission object.

Demand()

如果未对调用堆栈中处于较高位置的所有调用方授予当前实例所指定的权限,则在运行时强制 SecurityExceptionForces a SecurityException at run time if all callers higher in the call stack have not been granted the permission specified by the current instance.

Deny()

防止处于调用堆栈较高位置的调用函数使用可以调用此方法来访问当前实例指定资源的代码。Prevents callers higher in the call stack from using the code that calls this method to access the resource specified by the current instance.

Equals(Object)

确定指定的 CodeAccessPermission 对象是否等于当前的 CodeAccessPermissionDetermines whether the specified CodeAccessPermission object is equal to the current CodeAccessPermission.

FromXml(SecurityElement)

当在派生类中替代时,用 XML 编码重新构造具有指定状态的安全对象。When overridden in a derived class, reconstructs a security object with a specified state from an XML encoding.

GetHashCode()

获取 CodeAccessPermission 对象的哈希代码,此代码适合在哈希算法和数据结构(例如哈希表)中使用。Gets a hash code for the CodeAccessPermission object that is suitable for use in hashing algorithms and data structures such as a hash table.

GetType()

获取当前实例的 TypeGets the Type of the current instance.

(继承自 Object)
Intersect(IPermission)

通过派生类实现时,创建和返回是当前权限和指定权限的交集的权限。When implemented by a derived class, creates and returns a permission that is the intersection of the current permission and the specified permission.

IsSubsetOf(IPermission)

通过派生类实现时,确定当前权限是否为指定权限的子集。When implemented by a derived class, determines whether the current permission is a subset of the specified permission.

MemberwiseClone()

创建当前 Object 的浅表副本。Creates a shallow copy of the current Object.

(继承自 Object)
PermitOnly()

防止处于调用堆栈较高位置的调用函数使用此代码,此代码将调用此方法来访问除当前实例指定的资源以外的所有资源。Prevents callers higher in the call stack from using the code that calls this method to access all resources except for the resource specified by the current instance.

RevertAll()

导致当前帧以前所有的重写被删除且不再有效。Causes all previous overrides for the current frame to be removed and no longer in effect.

RevertAssert()

导致当前帧以前所有的 Assert() 被删除且不再有效。Causes any previous Assert() for the current frame to be removed and no longer in effect.

RevertDeny()

导致当前帧以前所有的 Deny() 被删除且不再有效。Causes any previous Deny() for the current frame to be removed and no longer in effect.

RevertPermitOnly()

导致当前帧以前所有的 PermitOnly() 被删除且不再有效。Causes any previous PermitOnly() for the current frame to be removed and no longer in effect.

ToString()

创建并返回当前权限对象的字符串表示形式。Creates and returns a string representation of the current permission object.

ToXml()

当在派生类中重写时,创建安全对象及其当前状态的 XML 编码。When overridden in a derived class, creates an XML encoding of the security object and its current state.

Union(IPermission)

当在派生类中重写时,则创建属于当前权限与指定权限的并集的权限。When overridden in a derived class, creates a permission that is the union of the current permission and the specified permission.

显式界面实现

IPermission.Demand()
IStackWalk.Assert()
IStackWalk.Demand()
IStackWalk.Deny()
IStackWalk.PermitOnly()

安全性

InheritanceDemand
使继承者能够提供证据并查看和修改策略。for the ability of inheritors to provide evidence and view and modify policy. 关联的枚举: ControlEvidenceControlPolicyAssociated enumerations: ControlEvidence, ControlPolicy.

适用于