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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// Mutex to guarantee serialization of RLZ key accesses.
#include "rlz/win/lib/lib_mutex.h"
#include <windows.h>
#include <Sddl.h> // For SDDL_REVISION_1, ConvertStringSecurityDescript..
#include <Aclapi.h> // For SetSecurityInfo
#include "base/logging.h"
#include "base/win/windows_version.h"
namespace {
const wchar_t kMutexName[] = L"{A946A6A9-917E-4949-B9BC-6BADA8C7FD63}";
} // namespace anonymous
namespace rlz_lib {
// Needed to allow synchronization across integrity levels.
static bool SetObjectToLowIntegrity(HANDLE object,
SE_OBJECT_TYPE type = SE_KERNEL_OBJECT) {
if (base::win::GetVersion() < base::win::VERSION_VISTA)
return true; // Not needed on XP.
// The LABEL_SECURITY_INFORMATION SDDL SACL to be set for low integrity.
static const wchar_t kLowIntegritySddlSacl[] = L"S:(ML;;NW;;;LW)";
bool result = false;
DWORD error = ERROR_SUCCESS;
PSECURITY_DESCRIPTOR security_descriptor = NULL;
PACL sacl = NULL;
BOOL sacl_present = FALSE;
BOOL sacl_defaulted = FALSE;
if (ConvertStringSecurityDescriptorToSecurityDescriptorW(
kLowIntegritySddlSacl, SDDL_REVISION_1, &security_descriptor, NULL)) {
if (GetSecurityDescriptorSacl(security_descriptor, &sacl_present,
&sacl, &sacl_defaulted)) {
error = SetSecurityInfo(object, type, LABEL_SECURITY_INFORMATION,
NULL, NULL, NULL, sacl);
result = (ERROR_SUCCESS == error);
}
LocalFree(security_descriptor);
}
return result;
}
LibMutex::LibMutex() : acquired_(false), mutex_(NULL) {
mutex_ = CreateMutex(NULL, false, kMutexName);
bool result = SetObjectToLowIntegrity(mutex_);
if (result) {
acquired_ = (WAIT_OBJECT_0 == WaitForSingleObject(mutex_, 5000L));
}
}
LibMutex::~LibMutex() {
if (acquired_) ReleaseMutex(mutex_);
CloseHandle(mutex_);
}
} // namespace rlz_lib
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