1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 // 5 // Mutex to guarantee serialization of RLZ key accesses. 6 7 #include "rlz/win/lib/lib_mutex.h" 8 9 #include <windows.h> 10 #include <Sddl.h> // For SDDL_REVISION_1, ConvertStringSecurityDescript.. 11 #include <Aclapi.h> // For SetSecurityInfo 12 13 #include "base/logging.h" 14 #include "base/win/windows_version.h" 15 16 namespace { 17 18 const wchar_t kMutexName[] = L"{A946A6A9-917E-4949-B9BC-6BADA8C7FD63}"; 19 20 } // namespace anonymous 21 22 namespace rlz_lib { 23 24 // Needed to allow synchronization across integrity levels. 25 static bool SetObjectToLowIntegrity(HANDLE object, 26 SE_OBJECT_TYPE type = SE_KERNEL_OBJECT) { 27 if (base::win::GetVersion() < base::win::VERSION_VISTA) 28 return true; // Not needed on XP. 29 30 // The LABEL_SECURITY_INFORMATION SDDL SACL to be set for low integrity. 31 static const wchar_t kLowIntegritySddlSacl[] = L"S:(ML;;NW;;;LW)"; 32 33 bool result = false; 34 DWORD error = ERROR_SUCCESS; 35 PSECURITY_DESCRIPTOR security_descriptor = NULL; 36 PACL sacl = NULL; 37 BOOL sacl_present = FALSE; 38 BOOL sacl_defaulted = FALSE; 39 40 if (ConvertStringSecurityDescriptorToSecurityDescriptorW( 41 kLowIntegritySddlSacl, SDDL_REVISION_1, &security_descriptor, NULL)) { 42 if (GetSecurityDescriptorSacl(security_descriptor, &sacl_present, 43 &sacl, &sacl_defaulted)) { 44 error = SetSecurityInfo(object, type, LABEL_SECURITY_INFORMATION, 45 NULL, NULL, NULL, sacl); 46 result = (ERROR_SUCCESS == error); 47 } 48 LocalFree(security_descriptor); 49 } 50 51 return result; 52 } 53 54 LibMutex::LibMutex() : acquired_(false), mutex_(NULL) { 55 mutex_ = CreateMutex(NULL, false, kMutexName); 56 bool result = SetObjectToLowIntegrity(mutex_); 57 if (result) { 58 acquired_ = (WAIT_OBJECT_0 == WaitForSingleObject(mutex_, 5000L)); 59 } 60 } 61 62 LibMutex::~LibMutex() { 63 if (acquired_) ReleaseMutex(mutex_); 64 CloseHandle(mutex_); 65 } 66 67 } // namespace rlz_lib 68
