WindowsIdentity.Impersonate WindowsIdentity.Impersonate WindowsIdentity.Impersonate WindowsIdentity.Impersonate Method

Définition

Permet à du code d'emprunter l'identité d'un utilisateur Windows différent.Allows code to impersonate a different Windows user.

Surcharges

Impersonate() Impersonate() Impersonate() Impersonate()

Emprunte l'identité de l'utilisateur représenté par l'objet WindowsIdentity.Impersonates the user represented by the WindowsIdentity object.

Impersonate(IntPtr) Impersonate(IntPtr) Impersonate(IntPtr) Impersonate(IntPtr)

Emprunte l'identité de l'utilisateur représenté par le jeton utilisateur spécifié.Impersonates the user represented by the specified user token.

Impersonate() Impersonate() Impersonate() Impersonate()

Emprunte l'identité de l'utilisateur représenté par l'objet WindowsIdentity.Impersonates the user represented by the WindowsIdentity object.

public:
 virtual System::Security::Principal::WindowsImpersonationContext ^ Impersonate();
public virtual System.Security.Principal.WindowsImpersonationContext Impersonate ();
abstract member Impersonate : unit -> System.Security.Principal.WindowsImpersonationContext
override this.Impersonate : unit -> System.Security.Principal.WindowsImpersonationContext
Public Overridable Function Impersonate () As WindowsImpersonationContext

Retours

Objet qui représente l'utilisateur Windows avant l'emprunt d'identité ; vous pouvez l'utiliser pour rétablir le contexte de l'utilisateur d'origine.An object that represents the Windows user prior to impersonation; this can be used to revert to the original user's context.

Exceptions

Une identité anonyme a tenté d'exécuter un emprunt d'identité.An anonymous identity attempted to perform an impersonation.

Une erreur Win32 s’est produite.A Win32 error occurred.

Exemples

L’exemple suivant montre comment obtenir un jeton de compte Windows en appelant Win32 non managée LogonUser (fonction) et comment utiliser ce jeton pour emprunter l’identité d’un autre utilisateur puis rétablir l’identité d’origine.The following example demonstrates how to obtain a Windows account token by calling the unmanaged Win32 LogonUser function, and how to use that token to impersonate another user and then revert to the original identity.

// This sample demonstrates the use of the WindowsIdentity class to impersonate a user.
// IMPORTANT NOTES: 
// This sample requests the user to enter a password on the console screen.
// Because the console window does not support methods allowing the password to be masked,
// it will be visible to anyone viewing the screen.
// On Windows Vista and later this sample must be run as an administrator. 

#using <System.dll>

using namespace System;
using namespace System::Runtime::InteropServices;
using namespace System::Security::Principal;
using namespace System::Security::Permissions;


[DllImport("advapi32.dll",SetLastError=true)]
bool LogonUser( String^ lpszUsername, String^ lpszDomain, String^ lpszPassword, int dwLogonType, int dwLogonProvider, IntPtr * phToken );

[DllImport("kernel32.dll",CharSet=CharSet::Auto)]
bool CloseHandle( IntPtr handle );

// Test harness.
// If you incorporate this code into a DLL, be sure to demand FullTrust.

[PermissionSetAttribute(SecurityAction::Demand,Name="FullTrust")]
int main()
{
   IntPtr tokenHandle = IntPtr(0);

   try
   {
      String^ userName;
      String^ domainName;
      
      // Get the user token for the specified user, domain, and password using the 
      // unmanaged LogonUser method.  
      // The local machine name can be used for the domain name to impersonate a user on this machine.
      Console::Write( "Enter the name of the domain on which to log on: " );
      domainName = Console::ReadLine();
      Console::Write( "Enter the login of a user on {0} that you wish to impersonate: ", domainName );
      userName = Console::ReadLine();
      Console::Write( "Enter the password for {0}: ", userName );
      const int LOGON32_PROVIDER_DEFAULT = 0;
      
      //This parameter causes LogonUser to create a primary token.
      const int LOGON32_LOGON_INTERACTIVE = 2;
      const int SecurityImpersonation = 2;
      tokenHandle = IntPtr::Zero;
      
      // Call LogonUser to obtain a handle to an access token.
      bool returnValue = LogonUser( userName, domainName, Console::ReadLine(), LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT,  &tokenHandle );
      Console::WriteLine( "LogonUser called." );
      if ( false == returnValue )
      {
         int ret = Marshal::GetLastWin32Error();
         Console::WriteLine( "LogonUser failed with error code : {0}", ret );
         throw gcnew System::ComponentModel::Win32Exception( ret );
      }
      Console::WriteLine( "Did LogonUser Succeed? {0}", (returnValue ? (String^)"Yes" : "No") );
      Console::WriteLine( "Value of Windows NT token: {0}", tokenHandle );
      
      // Check the identity.
      Console::WriteLine( "Before impersonation: {0}", WindowsIdentity::GetCurrent()->Name );
      
      // The token that is passed to the following constructor must 
      // be a primary token in order to use it for impersonation.
      WindowsIdentity^ newId = gcnew WindowsIdentity( tokenHandle );
      WindowsImpersonationContext^ impersonatedUser = newId->Impersonate();
      
      // Check the identity.
      Console::WriteLine( "After impersonation: {0}", WindowsIdentity::GetCurrent()->Name );
      
      // Stop impersonating the user.
      impersonatedUser->Undo();
      
      // Check the identity.
      Console::WriteLine( "After Undo: {0}", WindowsIdentity::GetCurrent()->Name );
      
      // Free the tokens.
      if ( tokenHandle != IntPtr::Zero )
            CloseHandle( tokenHandle );
   }
   catch ( Exception^ ex ) 
   {
      Console::WriteLine( "Exception occurred. {0}", ex->Message );
   }

}

// This sample demonstrates the use of the WindowsIdentity class to impersonate a user.
// IMPORTANT NOTES:
// This sample requests the user to enter a password on the console screen.
// Because the console window does not support methods allowing the password to be masked,
// it will be visible to anyone viewing the screen.
// On Windows Vista and later this sample must be run as an administrator. 


using System;
using System.Runtime.InteropServices;
using System.Security.Principal;
using System.Security.Permissions;
using Microsoft.Win32.SafeHandles;
using System.Runtime.ConstrainedExecution;
using System.Security;


public class ImpersonationDemo
{
    [DllImport("advapi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
    public static extern bool LogonUser(String lpszUsername, String lpszDomain, String lpszPassword,
        int dwLogonType, int dwLogonProvider, out SafeTokenHandle phToken);

    [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
    public extern static bool CloseHandle(IntPtr handle);

    // Test harness.
    // If you incorporate this code into a DLL, be sure to demand FullTrust.
    [PermissionSetAttribute(SecurityAction.Demand, Name = "FullTrust")]
    public static void Main(string[] args)
    {
        SafeTokenHandle safeTokenHandle;
        try
        {
            string userName, domainName;
            // Get the user token for the specified user, domain, and password using the
            // unmanaged LogonUser method.
            // The local machine name can be used for the domain name to impersonate a user on this machine.
            Console.Write("Enter the name of the domain on which to log on: ");
            domainName = Console.ReadLine();

            Console.Write("Enter the login of a user on {0} that you wish to impersonate: ", domainName);
            userName = Console.ReadLine();

            Console.Write("Enter the password for {0}: ", userName);

            const int LOGON32_PROVIDER_DEFAULT = 0;
            //This parameter causes LogonUser to create a primary token.
            const int LOGON32_LOGON_INTERACTIVE = 2;

            // Call LogonUser to obtain a handle to an access token.
            bool returnValue = LogonUser(userName, domainName, Console.ReadLine(),
                LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT,
                out safeTokenHandle);

            Console.WriteLine("LogonUser called.");

            if (false == returnValue)
            {
                int ret = Marshal.GetLastWin32Error();
                Console.WriteLine("LogonUser failed with error code : {0}", ret);
                throw new System.ComponentModel.Win32Exception(ret);
            }
            using (safeTokenHandle)
            {
                Console.WriteLine("Did LogonUser Succeed? " + (returnValue ? "Yes" : "No"));
                Console.WriteLine("Value of Windows NT token: " + safeTokenHandle);

                // Check the identity.
                Console.WriteLine("Before impersonation: "
                    + WindowsIdentity.GetCurrent().Name);
                // Use the token handle returned by LogonUser.
                using (WindowsIdentity newId = new WindowsIdentity(safeTokenHandle.DangerousGetHandle()))
                {
                    using (WindowsImpersonationContext impersonatedUser = newId.Impersonate())
                    {

                        // Check the identity.
                        Console.WriteLine("After impersonation: "
                            + WindowsIdentity.GetCurrent().Name);
                    }
                }
                // Releasing the context object stops the impersonation
                // Check the identity.
                Console.WriteLine("After closing the context: " + WindowsIdentity.GetCurrent().Name);
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine("Exception occurred. " + ex.Message);
        }

    }
}
public sealed class SafeTokenHandle : SafeHandleZeroOrMinusOneIsInvalid
{
    private SafeTokenHandle()
        : base(true)
    {
    }

    [DllImport("kernel32.dll")]
    [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
    [SuppressUnmanagedCodeSecurity]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool CloseHandle(IntPtr handle);

    protected override bool ReleaseHandle()
    {
        return CloseHandle(handle);
    }
}



' This sample demonstrates the use of the WindowsIdentity class to impersonate a user.
' IMPORTANT NOTES: 
' This sample requests the user to enter a password on the console screen.
' Because the console window does not support methods allowing the password to be masked,
' it will be visible to anyone viewing the screen.
' On Windows Vista and later this sample must be run as an administrator. 

Imports System
Imports System.Runtime.InteropServices
Imports System.Security.Principal
Imports System.Security.Permissions
Imports Microsoft.VisualBasic
Imports Microsoft.Win32.SafeHandles
Imports System.Runtime.ConstrainedExecution
Imports System.Security

Module Module1

    Public Class ImpersonationDemo

        'Private Declare Auto Function LogonUser Lib "advapi32.dll" (ByVal lpszUsername As [String], _
        '    ByVal lpszDomain As [String], ByVal lpszPassword As [String], _
        '    ByVal dwLogonType As Integer, ByVal dwLogonProvider As Integer, _
        '    ByRef phToken As IntPtr) As Boolean

        Private Declare Auto Function LogonUser Lib "advapi32.dll" (ByVal lpszUsername As [String], _
            ByVal lpszDomain As [String], ByVal lpszPassword As [String], _
            ByVal dwLogonType As Integer, ByVal dwLogonProvider As Integer, _
            <Out()> ByRef phToken As SafeTokenHandle) As Boolean

        Public Declare Auto Function CloseHandle Lib "kernel32.dll" (ByVal handle As IntPtr) As Boolean

        ' Test harness.
        ' If you incorporate this code into a DLL, be sure to demand FullTrust.
        <PermissionSetAttribute(SecurityAction.Demand, Name:="FullTrust")> _
        Public Overloads Shared Sub Main(ByVal args() As String)
            Dim safeTokenHandle As SafeTokenHandle = Nothing
            Dim tokenHandle As New IntPtr(0)
            Try


                Dim userName, domainName As String

                ' Get the user token for the specified user, domain, and password using the 
                ' unmanaged LogonUser method.  
                ' The local machine name can be used for the domain name to impersonate a user on this machine.
                Console.Write("Enter the name of a domain on which to log on: ")
                domainName = Console.ReadLine()

                Console.Write("Enter the login of a user on {0} that you wish to impersonate: ", domainName)
                userName = Console.ReadLine()

                Console.Write("Enter the password for {0}: ", userName)

                Const LOGON32_PROVIDER_DEFAULT As Integer = 0
                'This parameter causes LogonUser to create a primary token.
                Const LOGON32_LOGON_INTERACTIVE As Integer = 2

                ' Call LogonUser to obtain a handle to an access token.
                Dim returnValue As Boolean = LogonUser(userName, domainName, Console.ReadLine(), LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT, safeTokenHandle)

                Console.WriteLine("LogonUser called.")

                If False = returnValue Then
                    Dim ret As Integer = Marshal.GetLastWin32Error()
                    Console.WriteLine("LogonUser failed with error code : {0}", ret)
                    Throw New System.ComponentModel.Win32Exception(ret)

                    Return
                End If
                Using safeTokenHandle
                    Dim success As String
                    If returnValue Then success = "Yes" Else success = "No"
                    Console.WriteLine(("Did LogonUser succeed? " + success))
                    Console.WriteLine(("Value of Windows NT token: " + safeTokenHandle.DangerousGetHandle().ToString()))

                    ' Check the identity.
                    Console.WriteLine(("Before impersonation: " + WindowsIdentity.GetCurrent().Name))

                    ' Use the token handle returned by LogonUser.
                    Using newId As New WindowsIdentity(safeTokenHandle.DangerousGetHandle())
                        Using impersonatedUser As WindowsImpersonationContext = newId.Impersonate()

                            ' Check the identity.
                            Console.WriteLine(("After impersonation: " + WindowsIdentity.GetCurrent().Name))

                            ' Free the tokens.
                        End Using
                    End Using
                End Using
            Catch ex As Exception
                Console.WriteLine(("Exception occurred. " + ex.Message))
            End Try
        End Sub 'Main 
    End Class 'Class1
End Module

Public NotInheritable Class SafeTokenHandle
    Inherits SafeHandleZeroOrMinusOneIsInvalid

    Private Sub New()
        MyBase.New(True)

    End Sub 'New

    Private Declare Auto Function LogonUser Lib "advapi32.dll" (ByVal lpszUsername As [String], _
            ByVal lpszDomain As [String], ByVal lpszPassword As [String], _
            ByVal dwLogonType As Integer, ByVal dwLogonProvider As Integer, _
            ByRef phToken As IntPtr) As Boolean
    <DllImport("kernel32.dll"), ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success), SuppressUnmanagedCodeSecurity()> _
    Private Shared Function CloseHandle(ByVal handle As IntPtr) As <MarshalAs(UnmanagedType.Bool)> Boolean

    End Function
    Protected Overrides Function ReleaseHandle() As Boolean
        Return CloseHandle(handle)

    End Function 'ReleaseHandle
End Class 'SafeTokenHandle

Remarques

Sur les plateformes Windows NT, l’utilisateur actuel doit disposer des droits suffisants pour permettre l’emprunt d’identité.On Windows NT platforms, the current user must have sufficient rights to allow impersonation.

Notes pour les héritiers

Microsoft Windows 98 et les plates-formes Windows Millennium Edition (Windows Me) n’ayant pas de jetons utilisateur, l’emprunt d’identité ne peut pas avoir lieu sur ces plateformes.Because Microsoft Windows 98 and Windows Millennium Edition (Windows Me) platforms do not have user tokens, impersonation cannot take place on those platforms.

Notes pour les appelants

Après avoir utilisé Impersonate(), il est important d’appeler le Undo() méthode à la fin de l’emprunt d’identité.After using Impersonate(), it is important to call the Undo() method to end the impersonation.

Impersonate(IntPtr) Impersonate(IntPtr) Impersonate(IntPtr) Impersonate(IntPtr)

Emprunte l'identité de l'utilisateur représenté par le jeton utilisateur spécifié.Impersonates the user represented by the specified user token.

public:
 static System::Security::Principal::WindowsImpersonationContext ^ Impersonate(IntPtr userToken);
public static System.Security.Principal.WindowsImpersonationContext Impersonate (IntPtr userToken);
static member Impersonate : nativeint -> System.Security.Principal.WindowsImpersonationContext
Public Shared Function Impersonate (userToken As IntPtr) As WindowsImpersonationContext

Paramètres

userToken
IntPtr IntPtr IntPtr IntPtr

Handle d'un jeton de compte Windows.The handle of a Windows account token. Ce jeton est généralement récupéré par l'intermédiaire d'un appel à du code non managé, tel qu'un appel à la fonction LogonUser de l’API Windows.This token is usually retrieved through a call to unmanaged code, such as a call to the Windows API LogonUser function.

Retours

Objet qui représente l'utilisateur Windows avant l'emprunt d'identité ; vous pouvez utiliser cet objet pour rétablir le contexte de l'utilisateur d'origine.An object that represents the Windows user prior to impersonation; this object can be used to revert to the original user's context.

Exceptions

Windows a retourné le code d’état Windows NT STATUS_ACCESS_DENIED.Windows returned the Windows NT status code STATUS_ACCESS_DENIED.

Il n’y a pas suffisamment de mémoire disponible.There is insufficient memory available.

L’appelant n’a pas les autorisations requises.The caller does not have the correct permissions.

Exemples

L’exemple suivant montre comment obtenir un jeton de compte Windows en appelant Win32 non managée LogonUser (fonction) et comment utiliser ce jeton pour emprunter l’identité d’un autre utilisateur puis rétablir l’identité d’origine.The following example demonstrates how to obtain a Windows account token by calling the unmanaged Win32 LogonUser function, and how to use that token to impersonate another user and then revert to the original identity.

// This sample demonstrates the use of the WindowsIdentity class to impersonate a user.
// IMPORTANT NOTES:
// This sample requests the user to enter a password on the console screen.
// Because the console window does not support methods allowing the password to be masked,
// it will be visible to anyone viewing the screen.
// On Windows Vista and later this sample must be run as an administrator. 


using System;
using System.Runtime.InteropServices;
using System.Security.Principal;
using System.Security.Permissions;
using Microsoft.Win32.SafeHandles;
using System.Runtime.ConstrainedExecution;
using System.Security;


public class ImpersonationDemo
{
    [DllImport("advapi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
    public static extern bool LogonUser(String lpszUsername, String lpszDomain, String lpszPassword,
        int dwLogonType, int dwLogonProvider, out SafeTokenHandle phToken);

    [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
    public extern static bool CloseHandle(IntPtr handle);

    // Test harness.
    // If you incorporate this code into a DLL, be sure to demand FullTrust.
    [PermissionSetAttribute(SecurityAction.Demand, Name = "FullTrust")]
    public static void Main(string[] args)
    {
        SafeTokenHandle safeTokenHandle;
        try
        {
            string userName, domainName;
            // Get the user token for the specified user, domain, and password using the
            // unmanaged LogonUser method.
            // The local machine name can be used for the domain name to impersonate a user on this machine.
            Console.Write("Enter the name of the domain on which to log on: ");
            domainName = Console.ReadLine();

            Console.Write("Enter the login of a user on {0} that you wish to impersonate: ", domainName);
            userName = Console.ReadLine();

            Console.Write("Enter the password for {0}: ", userName);

            const int LOGON32_PROVIDER_DEFAULT = 0;
            //This parameter causes LogonUser to create a primary token.
            const int LOGON32_LOGON_INTERACTIVE = 2;

            // Call LogonUser to obtain a handle to an access token.
            bool returnValue = LogonUser(userName, domainName, Console.ReadLine(),
                LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT,
                out safeTokenHandle);

            Console.WriteLine("LogonUser called.");

            if (false == returnValue)
            {
                int ret = Marshal.GetLastWin32Error();
                Console.WriteLine("LogonUser failed with error code : {0}", ret);
                throw new System.ComponentModel.Win32Exception(ret);
            }
            using (safeTokenHandle)
            {
                Console.WriteLine("Did LogonUser Succeed? " + (returnValue ? "Yes" : "No"));
                Console.WriteLine("Value of Windows NT token: " + safeTokenHandle);

                // Check the identity.
                Console.WriteLine("Before impersonation: "
                    + WindowsIdentity.GetCurrent().Name);
                // Use the token handle returned by LogonUser.
                using (WindowsImpersonationContext impersonatedUser = WindowsIdentity.Impersonate(safeTokenHandle.DangerousGetHandle()))
                {

                    // Check the identity.
                    Console.WriteLine("After impersonation: "
                        + WindowsIdentity.GetCurrent().Name);
                }
                // Releasing the context object stops the impersonation
                // Check the identity.
                Console.WriteLine("After closing the context: " + WindowsIdentity.GetCurrent().Name);
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine("Exception occurred. " + ex.Message);
        }

    }
}
public sealed class SafeTokenHandle : SafeHandleZeroOrMinusOneIsInvalid
{
    private SafeTokenHandle()
        : base(true)
    {
    }

    [DllImport("kernel32.dll")]
    [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
    [SuppressUnmanagedCodeSecurity]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool CloseHandle(IntPtr handle);

    protected override bool ReleaseHandle()
    {
        return CloseHandle(handle);
    }
}



' This sample demonstrates the use of the WindowsIdentity class to impersonate a user.
' IMPORTANT NOTES: 
' This sample requests the user to enter a password on the console screen.
' Because the console window does not support methods allowing the password to be masked,
' it will be visible to anyone viewing the screen.
' On Windows Vista and later this sample must be run as an administrator. 

Imports System
Imports System.Runtime.InteropServices
Imports System.Security.Principal
Imports System.Security.Permissions
Imports Microsoft.VisualBasic
Imports Microsoft.Win32.SafeHandles
Imports System.Runtime.ConstrainedExecution
Imports System.Security

Module Module1

    Public Class ImpersonationDemo

        'Private Declare Auto Function LogonUser Lib "advapi32.dll" (ByVal lpszUsername As [String], _
        '    ByVal lpszDomain As [String], ByVal lpszPassword As [String], _
        '    ByVal dwLogonType As Integer, ByVal dwLogonProvider As Integer, _
        '    ByRef phToken As IntPtr) As Boolean

        Private Declare Auto Function LogonUser Lib "advapi32.dll" (ByVal lpszUsername As [String], _
            ByVal lpszDomain As [String], ByVal lpszPassword As [String], _
            ByVal dwLogonType As Integer, ByVal dwLogonProvider As Integer, _
            <Out()> ByRef phToken As SafeTokenHandle) As Boolean

        Public Declare Auto Function CloseHandle Lib "kernel32.dll" (ByVal handle As IntPtr) As Boolean

        ' Test harness.
        ' If you incorporate this code into a DLL, be sure to demand FullTrust.
        <PermissionSetAttribute(SecurityAction.Demand, Name:="FullTrust")> _
        Public Overloads Shared Sub Main(ByVal args() As String)
            Dim safeTokenHandle As SafeTokenHandle
            Dim tokenHandle As New IntPtr(0)
            Try


                Dim userName, domainName As String

                ' Get the user token for the specified user, domain, and password using the 
                ' unmanaged LogonUser method.  
                ' The local machine name can be used for the domain name to impersonate a user on this machine.
                Console.Write("Enter the name of a domain on which to log on: ")
                domainName = Console.ReadLine()

                Console.Write("Enter the login of a user on {0} that you wish to impersonate: ", domainName)
                userName = Console.ReadLine()

                Console.Write("Enter the password for {0}: ", userName)

                Const LOGON32_PROVIDER_DEFAULT As Integer = 0
                'This parameter causes LogonUser to create a primary token.
                Const LOGON32_LOGON_INTERACTIVE As Integer = 2

                ' Call LogonUser to obtain a handle to an access token.
                Dim returnValue As Boolean = LogonUser(userName, domainName, Console.ReadLine(), LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT, safeTokenHandle)

                Console.WriteLine("LogonUser called.")

                If False = returnValue Then
                    Dim ret As Integer = Marshal.GetLastWin32Error()
                    Console.WriteLine("LogonUser failed with error code : {0}", ret)
                    Throw New System.ComponentModel.Win32Exception(ret)

                    Return
                End If
                Using safeTokenHandle
                    Dim success As String
                    If returnValue Then success = "Yes" Else success = "No"
                    Console.WriteLine(("Did LogonUser succeed? " + success))
                    Console.WriteLine(("Value of Windows NT token: " + safeTokenHandle.DangerousGetHandle().ToString()))

                    ' Check the identity.
                    Console.WriteLine(("Before impersonation: " + WindowsIdentity.GetCurrent().Name))

                    ' Use the token handle returned by LogonUser.
                    Using impersonatedUser As WindowsImpersonationContext = WindowsIdentity.Impersonate(safeTokenHandle.DangerousGetHandle())

                        ' Check the identity.
                        Console.WriteLine(("After impersonation: " + WindowsIdentity.GetCurrent().Name))

                        ' Free the tokens.
                    End Using
                End Using
            Catch ex As Exception
                Console.WriteLine(("Exception occurred. " + ex.Message))
            End Try
        End Sub 'Main 
    End Class 'Class1
End Module

Public NotInheritable Class SafeTokenHandle
    Inherits SafeHandleZeroOrMinusOneIsInvalid

    Private Sub New()
        MyBase.New(True)

    End Sub 'New

    Private Declare Auto Function LogonUser Lib "advapi32.dll" (ByVal lpszUsername As [String], _
            ByVal lpszDomain As [String], ByVal lpszPassword As [String], _
            ByVal dwLogonType As Integer, ByVal dwLogonProvider As Integer, _
            ByRef phToken As IntPtr) As Boolean
    <DllImport("kernel32.dll"), ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success), SuppressUnmanagedCodeSecurity()> _
    Private Shared Function CloseHandle(ByVal handle As IntPtr) As <MarshalAs(UnmanagedType.Bool)> Boolean

    End Function
    Protected Overrides Function ReleaseHandle() As Boolean
        Return CloseHandle(handle)

    End Function 'ReleaseHandle
End Class 'SafeTokenHandle

Remarques

Sur les plateformes Windows NT, l’utilisateur actuel doit disposer des droits suffisants pour permettre l’emprunt d’identité.On Windows NT platforms, the current user must have sufficient rights to allow impersonation.

Notes

Appelant le Impersonate(IntPtr) méthode avec un userToken valeur Zero est équivalent à l’appel Win32 RevertToSelf (fonction).Calling the Impersonate(IntPtr) method with a userToken value of Zero is equivalent to calling the Win32 RevertToSelf function. Si un autre utilisateur est actuellement empruntée, le contrôle revient à l’utilisateur d’origine.If another user is currently being impersonated, control reverts to the original user.

Pour plus d’informations sur les appels au code non managé, consultez consommation de fonctions DLL non managées.For more information about calls to unmanaged code, see Consuming Unmanaged DLL Functions.

Notes pour les héritiers

Microsoft Windows 98 et les plates-formes Windows Millennium Edition (Windows Me) n’ayant pas de jetons utilisateur, l’emprunt d’identité ne peut pas avoir lieu sur ces plateformes.Because Microsoft Windows 98 and Windows Millennium Edition (Windows Me) platforms do not have user tokens, impersonation cannot take place on those platforms.

Notes pour les appelants

Après avoir utilisé Impersonate(IntPtr), il est important d’appeler le Undo() méthode à la fin de l’emprunt d’identité.After using Impersonate(IntPtr), it is important to call the Undo() method to end the impersonation.

Sécurité

SecurityPermission
pour la possibilité de manipuler l’objet principal et d’accéder au code non managé.for the ability to manipulate the principal object and access unmanaged code. Énumérations associées : ControlPrincipal et UnmanagedCodeAssociated enumerations: ControlPrincipal and UnmanagedCode

S’applique à