Marshal.ZeroFreeGlobalAllocUnicode(IntPtr) 方法
定義
重要
部分資訊涉及發行前產品,在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊,不做任何明確或隱含的瑕疵擔保。
釋放之前使用 SecureStringToGlobalAllocUnicode(SecureString) 方法配置的 Unmanaged 字串指標。
public:
static void ZeroFreeGlobalAllocUnicode(IntPtr s);
[System.Security.SecurityCritical]
public static void ZeroFreeGlobalAllocUnicode (IntPtr s);
public static void ZeroFreeGlobalAllocUnicode (IntPtr s);
[<System.Security.SecurityCritical>]
static member ZeroFreeGlobalAllocUnicode : nativeint -> unit
static member ZeroFreeGlobalAllocUnicode : nativeint -> unit
Public Shared Sub ZeroFreeGlobalAllocUnicode (s As IntPtr)
參數
- s
-
IntPtr
nativeint
要釋放的 Unmanaged 字串的位址。
- 屬性
範例
下列範例示範如何搭配 Unmanaged LogonUser
函式使用 SecureStringToGlobalAllocUnicode 方法,以使用 SecureString 類別執行模擬。 然後,此範例會 ZeroFreeGlobalAllocUnicode 使用 方法來零出並釋放 Unmanaged 字串參考。
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
備註
方法 ZeroFreeGlobalAllocUnicode 會先零出,然後釋放使用 SecureStringToGlobalAllocUnicode 方法配置的 Unmanaged 記憶體。
適用於
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