Marshal.SecureStringToGlobalAllocUnicode(SecureString) Metoda

Definice

Obor názvů:

System.Runtime.InteropServices

Sestavení:

System.Runtime.InteropServices.dll

Zdroj:

Marshal.cs

Důležité

Toto rozhraní API neodpovídá specifikaci CLS.

Zkopíruje obsah spravovaného SecureString objektu do nespravované paměti.

public:
 static IntPtr SecureStringToGlobalAllocUnicode(System::Security::SecureString ^ s);

public static IntPtr SecureStringToGlobalAllocUnicode (System.Security.SecureString s);

static member SecureStringToGlobalAllocUnicode : System.Security.SecureString -> nativeint

Public Shared Function SecureStringToGlobalAllocUnicode (s As SecureString) As IntPtr

Parametry

s

SecureString

Spravovaný objekt, který chcete zkopírovat.

Návraty

IntPtr

nativeint

Adresa v nespravované paměti, kde s byla zkopírována, nebo 0, pokud s je objekt, SecureString jehož délka je 0.

Výjimky

ArgumentNullException

Parametr s je null.

OutOfMemoryException

Není k dispozici dostatek paměti.

Příklady

Následující příklad ukazuje, jak použít metodu SecureStringToGlobalAllocUnicode s nespravovanou LogonUser funkcí k provedení zosobnění s SecureString třídou . Příklad pak použije metodu ZeroFreeGlobalAllocUnicode k vynulování a uvolnění nespravovaného odkazu na řetězec.

using System;
using System.ComponentModel;
using System.Runtime.InteropServices;
using System.Security;
using System.Security.Principal;

class Example
{
     // Define the Windows LogonUser and CloseHandle functions.
     [DllImport("advapi32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
     internal static extern bool LogonUser(String username, String domain, IntPtr password,
             int logonType, int logonProvider, ref IntPtr token);

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

     // Define the required LogonUser enumerations.
     const int LOGON32_PROVIDER_DEFAULT = 0;
     const int LOGON32_LOGON_INTERACTIVE = 2;

     static void Main()
     {
          // Display the current user before impersonation.
          Console.WriteLine("Before impersonation: {0}",
                            WindowsIdentity.GetCurrent().Name);

          // Ask the user for a network domain.
          Console.Write("Please enter your domain: ");
          string domain = Console.ReadLine();

          // Ask the user for a user name.
          Console.Write("Please enter your user name: ");
          string username = Console.ReadLine();

          // Ask the user for a password.
          Console.Write("Please enter your password: ");
          SecureString passWord = GetPassword();

          // Impersonate the account provided by the user.
          try {
             WindowsImpersonationContext userContext =
                           ImpersonateUser(passWord, username, domain);
             // Display the current user after impersonation.
             Console.WriteLine("After impersonation: {0}",
                               WindowsIdentity.GetCurrent().Name);
          }
          catch (ArgumentException e) {
             Console.WriteLine("{0}: {1}", e.GetType().Name, e.Message);
          }
          catch (Win32Exception e) {
             Console.WriteLine("{0}: {1}", e.GetType().Name, e.Message);
          }
          finally {
             passWord.Dispose();
          }
     }

     public static SecureString GetPassword()
     {
         SecureString password = new SecureString();

         // get the first character of the password
         ConsoleKeyInfo nextKey = Console.ReadKey(true);

         while (nextKey.Key != ConsoleKey.Enter) {
             if (nextKey.Key == ConsoleKey.Backspace) {
                 if (password.Length > 0) {
                     password.RemoveAt(password.Length - 1);

                     // erase the last * as well
                     Console.Write(nextKey.KeyChar);
                     Console.Write(" ");
                     Console.Write(nextKey.KeyChar);
                 }
             }
             else {
                 password.AppendChar(nextKey.KeyChar);
                 Console.Write("*");
             }

             nextKey = Console.ReadKey(true);
         }

         Console.WriteLine();

         // lock the password down
         password.MakeReadOnly();
         return password;
     }

     public static WindowsImpersonationContext ImpersonateUser(SecureString password, string userName, string domainName)
     {
         IntPtr tokenHandle = IntPtr.Zero;
         IntPtr passwordPtr = IntPtr.Zero;
         bool returnValue = false;
         int error = 0;

         // Marshal the SecureString to unmanaged memory.
         passwordPtr = Marshal.SecureStringToGlobalAllocUnicode(password);

         // Pass LogonUser the unmanaged (and decrypted) copy of the password.
         returnValue = LogonUser(userName, domainName, passwordPtr,
                                 LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT,
                                 ref tokenHandle);
         if (!returnValue && tokenHandle == IntPtr.Zero)
            error = Marshal.GetLastWin32Error();

         // Perform cleanup whether or not the call succeeded.
         // Zero-out and free the unmanaged string reference.
         Marshal.ZeroFreeGlobalAllocUnicode(passwordPtr);
         // Close the token handle.
         CloseHandle(tokenHandle);

         // Throw an exception if an error occurred.
         if (error != 0) {
             throw new System.ComponentModel.Win32Exception(error);
         }
         // The token that is passed to the following constructor must
         // be a primary token in order to use it for impersonation.
         WindowsIdentity newId = new WindowsIdentity(tokenHandle);

         return newId.Impersonate();
     }
}

Imports System.ComponentModel
Imports System.Runtime.InteropServices
Imports System.Security
Imports System.Security.Principal

Module Example
    ' PInvoke into the Win32 API to provide access to the
    ' LogonUser and CloseHandle functions.
    <DllImport("advapi32.dll", SetLastError:=True, CharSet:=CharSet.Unicode)> _
    Function LogonUser(ByVal username As String, ByVal domain As String, _
                       ByVal password As IntPtr, ByVal logonType As Integer, _
                       ByVal logonProvider As Integer, ByRef token As IntPtr) _
                       As Boolean
    End Function

    <DllImport("kernel32.dll", CharSet:=CharSet.Auto)> _
    Function CloseHandle(ByVal handle As IntPtr) As Boolean
    End Function

    ' Define the required LogonUser enumerations.
    Const LOGON32_PROVIDER_DEFAULT As Integer = 0
    Const LOGON32_LOGON_INTERACTIVE As Integer = 2

    Sub Main(ByVal args() As String)
        ' Display the current user before impersonation.
        Console.WriteLine("Before impersonation: {0}",
                          WindowsIdentity.GetCurrent().Name)

        ' Ask the user for a network domain.
        Console.Write("Please enter your domain:")
        Dim domain As String = Console.ReadLine()

        ' Ask the user for a user name.
        Console.Write("Please enter your user name:")
        Dim username As String = Console.ReadLine()

        ' Ask the user for a password.
        Console.Write("Please enter your password:")
        Dim passWord As SecureString = GetPassword()

        ' Impersonate the account provided by the user.
        Try
            Dim userContext As WindowsImpersonationContext =
                            ImpersonateUser(passWord, username, domain)
            ' Display the current user after impersonation.
            Console.WriteLine("After impersonation: {0}",
                              WindowsIdentity.GetCurrent().Name)
         Catch e As ArgumentException
            Console.WriteLine(e.Message)
             Console.WriteLine("{0}: {1}", e.GetType().Name, e.Message)
         Catch e As Win32Exception
             Console.WriteLine("{0}: {1}", e.GetType().Name, e.Message)
         Finally
              passWord.Dispose()
         End Try
    End Sub

    Function GetPassword() As SecureString
        Dim password As New SecureString()

        ' get the first character of the password
        Dim nextKey As ConsoleKeyInfo = Console.ReadKey(True)

        While nextKey.Key <> ConsoleKey.Enter
            If nextKey.Key = ConsoleKey.BackSpace Then
                If password.Length > 0 Then
                    password.RemoveAt(password.Length - 1)

                    ' erase the last * as well
                    Console.Write(nextKey.KeyChar)
                    Console.Write(" ")
                    Console.Write(nextKey.KeyChar)
                End If
            Else
                password.AppendChar(nextKey.KeyChar)
                Console.Write("*")
            End If

            nextKey = Console.ReadKey(True)
        End While

        Console.WriteLine()

        ' lock the password down
        password.MakeReadOnly()
        Return password
    End Function

    Function ImpersonateUser(ByVal password As SecureString,
                             ByVal userName As String,
                             ByVal domainName As String) As WindowsImpersonationContext
        Dim tokenHandle As IntPtr = IntPtr.Zero
        Dim passwordPtr As IntPtr = IntPtr.Zero
        Dim returnValue As Boolean = False
        Dim err As Integer = 0
        
        ' Marshal the SecureString to unmanaged memory.
        passwordPtr = Marshal.SecureStringToGlobalAllocUnicode(password)

        ' Pass LogonUser the unmanaged (and decrypted) copy of the password.
        returnValue = LogonUser(userName, domainName, passwordPtr,
                                LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT,
                                tokenHandle)
        If Not returnValue AndAlso tokenHandle = IntPtr.Zero Then
            err = Marshal.GetLastWin32Error()
        End If
        
        ' Perform cleanup whether or not the call succeeded.
        ' Zero-out and free the unmanaged string reference.
        Marshal.ZeroFreeGlobalAllocUnicode(passwordPtr)
        ' Close the token handle.
        CloseHandle(tokenHandle)

        ' Throw an exception if an error occurred.
        If err <> 0 Then
            Throw New System.ComponentModel.Win32Exception(err)
        End If
        ' The token that is passed to the following constructor must 
        ' be a primary token in order to use it for impersonation.
        Dim newId As New WindowsIdentity(tokenHandle)

        Return newId.Impersonate()
    End Function
End Module

Poznámky

Metoda SecureStringToGlobalAllocUnicode je užitečná pro vlastní zařazování nebo pro použití při kombinování spravovaného a nespravovaného kódu. Vzhledem k tomu, že tato metoda přiděluje nespravovanou paměť potřebnou pro řetězec, vždy uvolněte paměť voláním ZeroFreeGlobalAllocUnicode metody .