reactos/win32ss/printing/base/spoolss/context.c

   1 /*
   2  * PROJECT:     ReactOS Spooler Router
   3  * LICENSE:     GNU LGPL v2.1 or any later version as published by the Free Software Foundation
   4  * PURPOSE:     Functions related to switching between security contexts
   5  * COPYRIGHT:   Copyright 2015 Colin Finck <colin@reactos.org>
   6  */
   7
   8 #include "precomp.h"
   9
  10 /**
  11  * @see RevertToPrinterSelf
  12  */
  13 BOOL WINAPI
  14 ImpersonatePrinterClient(HANDLE hToken)
  15 {
  16     if (!hToken)
  17     {
  18         SetLastError(ERROR_INVALID_HANDLE);
  19         return FALSE;
  20     }
  21
  22     if (!SetThreadToken(NULL, hToken))
  23     {
  24         ERR("SetThreadToken failed with error %lu!\n", GetLastError());
  25         CloseHandle(hToken);
  26         return FALSE;
  27     }
  28
  29     CloseHandle(hToken);
  30     return TRUE;
  31 }
  32
  33 /**
  34  * RevertToPrinterSelf reverts the security context from the current user's context back to the process context.
  35  * As spoolss.dll is used by spoolsv.exe, this is usually the SYSTEM security context.
  36  *
  37  * Unlike the traditional ImpersonateClient and then RevertToSelf approach, we do it the other way round here,
  38  * because spoolss.dll is delay-loaded by spoolsv.exe in the current user's context. Use RevertToPrinterSelf then to
  39  * return to the SYSTEM context for specific tasks.
  40  */
  41 HANDLE WINAPI
  42 RevertToPrinterSelf()
  43 {
  44     HANDLE hToken;
  45
  46     // Retrieve our current impersonation token
  47     if (!OpenThreadToken(GetCurrentThread(), TOKEN_IMPERSONATE, TRUE, &hToken))
  48     {
  49         ERR("OpenThreadToken failed with error %lu!\n", GetLastError());
  50         return NULL;
  51     }
  52
  53     // Tell the thread to stop impersonating
  54     if (!SetThreadToken(NULL, NULL))
  55     {
  56         ERR("SetThreadToken failed with error %lu!\n", GetLastError());
  57         return NULL;
  58     }
  59
  60     // Return the token required for reverting back to impersonation in ImpersonatePrinterClient
  61     return hToken;
  62 }