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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices; // DllImport
using System.Security.Principal; // WindowsImpersonationContext
using System.ComponentModel;
namespace Util
{
public class Impersonation : IDisposable
{
#region Dll Imports
/// <summary>
/// Closes an open object handle.
/// </summary>
/// <param name="hObject">A handle to an open object.</param>
/// <returns><c>True</c> when succeeded; otherwise <c>false</c>.</returns>
[DllImport("kernel32.dll")]
private static extern Boolean CloseHandle(IntPtr hObject);
/// <summary>
/// Attempts to log a user on to the local computer.
/// </summary>
/// <param name="username">This is the name of the user account to log on to.
/// If you use the user principal name (UPN) format, user@DNSdomainname, the
/// domain parameter must be <c>null</c>.</param>
/// <param name="domain">Specifies the name of the domain or server whose
/// account database contains the lpszUsername account. If this parameter
/// is <c>null</c>, the user name must be specified in UPN format. If this
/// parameter is ".", the function validates the account by using only the
/// local account database.</param>
/// <param name="password">The password</param>
/// <param name="logonType">The logon type</param>
/// <param name="logonProvider">The logon provides</param>
/// <param name="userToken">The out parameter that will contain the user
/// token when method succeeds.</param>
/// <returns><c>True</c> when succeeded; otherwise <c>false</c>.</returns>
[DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern bool LogonUser(string username, string domain,
string password, LogonType logonType,
LogonProvider logonProvider,
out IntPtr userToken);
/// <summary>
/// Creates a new access token that duplicates one already in existence.
/// </summary>
/// <param name="token">Handle to an access token.</param>
/// <param name="impersonationLevel">The impersonation level.</param>
/// <param name="duplication">Reference to the token to duplicate.</param>
/// <returns></returns>
[DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern bool DuplicateToken(IntPtr token, int impersonationLevel,
ref IntPtr duplication);
/// <summary>
/// The ImpersonateLoggedOnUser function lets the calling thread impersonate the
/// security context of a logged-on user. The user is represented by a token handle.
/// </summary>
/// <param name="userToken">Handle to a primary or impersonation access token that represents a logged-on user.</param>
/// <returns>If the function succeeds, the return value is nonzero.</returns>
[DllImport("advapi32.dll", SetLastError = true)]
static extern bool ImpersonateLoggedOnUser(IntPtr userToken);
#endregion
#region Private members
/// <summary>
/// <c>true</c> if disposed; otherwise, <c>false</c>.
/// </summary>
private bool _disposed;
/// <summary>
/// Holds the created impersonation context and will be used
/// for reverting to previous user.
/// </summary>
private WindowsImpersonationContext _impersonationContext;
#endregion
#region Ctor & Dtor
/// <summary>
/// Initializes a new instance of the <see cref="Impersonation"/> class and
/// impersonates as a built in service account.
/// </summary>
/// <param name="builtinUser">The built in user to impersonate - either
/// Local Service or Network Service. These users can only be impersonated
/// by code running as System.</param>
public Impersonation(BuiltinUser builtinUser)
: this(String.Empty, "NT AUTHORITY", String.Empty, LogonType.Service, builtinUser)
{
}
/// <summary>
/// Initializes a new instance of the <see cref="Impersonation"/> class and
/// impersonates with the specified credentials.
/// </summary>
/// <param name="username">his is the name of the user account to log on
/// to. If you use the user principal name (UPN) format,
/// user@DNS_domain_name, the lpszDomain parameter must be <c>null</c>.</param>
/// <param name="domain">The name of the domain or server whose account
/// database contains the lpszUsername account. If this parameter is
/// <c>null</c>, the user name must be specified in UPN format. If this
/// parameter is ".", the function validates the account by using only the
/// local account database.</param>
/// <param name="password">The plaintext password for the user account.</param>
public Impersonation(String username, String domain, String password)
: this(username, domain, password, LogonType.Interactive, BuiltinUser.None)
{
}
private Impersonation(String username, String domain, String password, LogonType logonType, BuiltinUser builtinUser)
{
switch (builtinUser)
{
case BuiltinUser.None: if (String.IsNullOrEmpty(username)) return; break;
case BuiltinUser.LocalService: username = "LOCAL SERVICE"; break;
case BuiltinUser.NetworkService: username = "NETWORK SERVICE"; break;
}
IntPtr userToken = IntPtr.Zero;
IntPtr userTokenDuplication = IntPtr.Zero;
// Logon with user and get token.
bool loggedOn = LogonUser(username, domain, password,
logonType, LogonProvider.Default,
out userToken);
if (loggedOn)
{
try
{
// Create a duplication of the usertoken, this is a solution
// for the known bug that is published under KB article Q319615.
if (DuplicateToken(userToken, 2, ref userTokenDuplication))
{
// Create windows identity from the token and impersonate the user.
WindowsIdentity identity = new WindowsIdentity(userTokenDuplication);
_impersonationContext = identity.Impersonate();
}
else
{
// Token duplication failed!
// Use the default ctor overload
// that will use Mashal.GetLastWin32Error();
// to create the exceptions details.
throw new Win32Exception();
}
}
finally
{
// Close usertoken handle duplication when created.
if (!userTokenDuplication.Equals(IntPtr.Zero))
{
// Closes the handle of the user.
CloseHandle(userTokenDuplication);
userTokenDuplication = IntPtr.Zero;
}
// Close usertoken handle when created.
if (!userToken.Equals(IntPtr.Zero))
{
// Closes the handle of the user.
CloseHandle(userToken);
userToken = IntPtr.Zero;
}
}
}
else
{
// Logon failed!
// Use the default ctor overload that
// will use Mashal.GetLastWin32Error();
// to create the exceptions details.
throw new Win32Exception();
}
}
/// <summary>
/// Releases unmanaged resources and performs other cleanup operations before the
/// <see cref="Born2Code.Net.Impersonation"/> is reclaimed by garbage collection.
/// </summary>
~Impersonation()
{
Dispose(false);
}
#endregion
#region Public methods
/// <summary>
/// Reverts to the previous user.
/// </summary>
public void Revert()
{
if (_impersonationContext != null)
{
// Revert to previour user.
_impersonationContext.Undo();
_impersonationContext = null;
}
}
#endregion
#region IDisposable implementation.
/// <summary>
/// Performs application-defined tasks associated with freeing, releasing, or
/// resetting unmanaged resources and will revent to the previous user when
/// the impersonation still exists.
/// </summary>
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
/// <summary>
/// Performs application-defined tasks associated with freeing, releasing, or
/// resetting unmanaged resources and will revent to the previous user when
/// the impersonation still exists.
/// </summary>
/// <param name="disposing">Specify <c>true</c> when calling the method directly
/// or indirectly by a user’s code; Otherwise <c>false</c>.
protected virtual void Dispose(bool disposing)
{
if (!_disposed)
{
Revert();
_disposed = true;
}
}
#endregion
}
#region Enums
public enum LogonType : int
{
/// <summary>
/// This logon type is intended for users who will be interactively using the computer, such as a user being logged on
/// by a terminal server, remote shell, or similar process.
/// This logon type has the additional expense of caching logon information for disconnected operations;
/// therefore, it is inappropriate for some client/server applications,
/// such as a mail server.
/// </summary>
Interactive = 2,
/// <summary>
/// This logon type is intended for high performance servers to authenticate plaintext passwords.
/// The LogonUser function does not cache credentials for this logon type.
/// </summary>
Network = 3,
/// <summary>
/// This logon type is intended for batch servers, where processes may be executing on behalf of a user without
/// their direct intervention. This type is also for higher performance servers that process many plaintext
/// authentication attempts at a time, such as mail or Web servers.
/// The LogonUser function does not cache credentials for this logon type.
/// </summary>
Batch = 4,
/// <summary>
/// Indicates a service-type logon. The account provided must have the service privilege enabled.
/// </summary>
Service = 5,
/// <summary>
/// This logon type is for GINA DLLs that log on users who will be interactively using the computer.
/// This logon type can generate a unique audit record that shows when the workstation was unlocked.
/// </summary>
Unlock = 7,
/// <summary>
/// This logon type preserves the name and password in the authentication package, which allows the server to make
/// connections to other network servers while impersonating the client. A server can accept plaintext credentials
/// from a client, call LogonUser, verify that the user can access the system across the network, and still
/// communicate with other servers.
/// NOTE: Windows NT: This value is not supported.
/// </summary>
NetworkCleartText = 8,
/// <summary>
/// This logon type allows the caller to clone its current token and specify new credentials for outbound connections.
/// The new logon session has the same local identifier but uses different credentials for other network connections.
/// NOTE: This logon type is supported only by the LOGON32_PROVIDER_WINNT50 logon provider.
/// NOTE: Windows NT: This value is not supported.
/// </summary>
NewCredentials = 9,
}
public enum LogonProvider : int
{
/// <summary>
/// Use the standard logon provider for the system.
/// The default security provider is negotiate, unless you pass NULL for the domain name and the user name
/// is not in UPN format. In this case, the default provider is NTLM.
/// NOTE: Windows 2000/NT: The default security provider is NTLM.
/// </summary>
Default = 0,
}
public enum BuiltinUser
{
None,
LocalService,
NetworkService
}
#endregion
} |
