chrome_elf/blacklist/blacklist.cc - chromium/src - Git at Google

 // Copyright 2013 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.

 #include "chrome_elf/blacklist/blacklist.h"

 #include <assert.h>
 #include <string.h>

 #include <vector>

 #include "chrome/install_static/install_util.h"
 #include "chrome_elf/blacklist/blacklist_interceptions.h"
 #include "chrome_elf/chrome_elf_constants.h"
 #include "chrome_elf/hook_util/hook_util.h"
 #include "chrome_elf/nt_registry/nt_registry.h"
 #include "sandbox/win/src/interception_internal.h"
 #include "sandbox/win/src/internal_types.h"
 #include "sandbox/win/src/service_resolver.h"

 // http://blogs.msdn.com/oldnewthing/archive/2004/10/25/247180.aspx
 extern "C" IMAGE_DOS_HEADER __ImageBase;

 namespace blacklist {

 // The DLLs listed here are known (or under strong suspicion) of causing crashes
 // when they are loaded in the browser. DLLs should only be added to this list
 // if there is nothing else Chrome can do to prevent those crashes.
 // For more information about how this list is generated, and how to get off
 // of it, see:
 // https://sites.google.com/a/chromium.org/dev/Home/third-party-developers
 // NOTE: Please remember to update the DllHash enum in histograms.xml when
 //       adding a new value to the blacklist.
 const wchar_t* g_troublesome_dlls[kTroublesomeDllsMaxCount] = {
     L"949ba8b6a9.dll",           // Coupon Time.
     L"activedetect32.dll",       // Lenovo One Key Theater.
                                  // See crbug.com/379218.
     L"activedetect64.dll",       // Lenovo One Key Theater.
     L"bitguard.dll",             // Unknown (suspected malware).
     L"bsvc.dll",                 // Unknown (suspected adware).
     L"chrmxtn.dll",              // Unknown (keystroke logger).
     L"cplushook.dll",            // Unknown (suspected malware).
     L"crdli.dll",                // Linkury Inc.
     L"crdli64.dll",              // Linkury Inc.
     L"datamngr.dll",             // Unknown (suspected adware).
     L"dpinterface32.dll",        // Unknown (suspected adware).
     L"explorerex.dll",           // Unknown (suspected adware).
     L"hk.dll",                   // Unknown (keystroke logger).
     L"libapi2hook.dll",          // V-Bates.
     L"libinject.dll",            // V-Bates.
     L"libinject2.dll",           // V-Bates.
     L"libredir2.dll",            // V-Bates.
     L"libsvn_tsvn32.dll",        // TortoiseSVN.
     L"libwinhook.dll",           // V-Bates.
     L"lmrn.dll",                 // Unknown.
     L"minisp.dll",               // Unknown (suspected malware).
     L"minisp32.dll",             // Unknown (suspected malware).
     L"offerswizarddll.dll",      // Unknown (suspected adware).
     L"safetynut.dll",            // Unknown (suspected adware).
     L"smdmf.dll",                // Unknown (suspected adware).
     L"spappsv32.dll",            // Unknown (suspected adware).
     L"systemk.dll",              // Unknown (suspected adware).
     L"vntsrv.dll",               // Virtual New Tab by APN LLC.
     L"wajam_goblin_64.dll",      // Wajam Internet Technologies.
     L"wajam_goblin.dll",         // Wajam Internet Technologies.
     L"windowsapihookdll32.dll",  // Lenovo One Key Theater.
                                  // See crbug.com/379218.
     L"windowsapihookdll64.dll",  // Lenovo One Key Theater.
     L"virtualcamera.ax",         // %PROGRAMFILES%\ASUS\VirtualCamera.
                                  // See crbug.com/422522.
     L"ycwebcamerasource.ax",     // CyberLink Youcam, crbug.com/424159
     // Keep this null pointer here to mark the end of the list.
     NULL,
 };

 bool g_blocked_dlls[kTroublesomeDllsMaxCount] = {};
 int g_num_blocked_dlls = 0;

 }  // namespace blacklist

 // Allocate storage for thunks in a page of this module to save on doing
 // an extra allocation at run time.
 #pragma section(".crthunk", read, execute)
 __declspec(allocate(".crthunk")) sandbox::ThunkData g_thunk_storage;

 namespace {

 // Record if the blacklist was successfully initialized so processes can easily
 // determine if the blacklist is enabled for them.
 bool g_blacklist_initialized = false;

 }  // namespace

 namespace blacklist {

 #if defined(_WIN64)
 // Allocate storage for the pointer to the old NtMapViewOfSectionFunction.
 #pragma section(".oldntmap", write, read)
 __declspec(allocate(".oldntmap"))
     NtMapViewOfSectionFunction g_nt_map_view_of_section_func = NULL;
 #endif

 bool LeaveSetupBeacon() {
   HANDLE key_handle = INVALID_HANDLE_VALUE;

   if (!nt::CreateRegKey(nt::HKCU, kRegistryBeaconPath,
                         KEY_QUERY_VALUE | KEY_SET_VALUE, &key_handle))
     return false;

   DWORD blacklist_state = BLACKLIST_STATE_MAX;
   if (!nt::QueryRegValueDWORD(key_handle, kBeaconState, &blacklist_state) ||
       blacklist_state == BLACKLIST_DISABLED) {
     nt::CloseRegKey(key_handle);
     return false;
   }

   // Handle attempt count.
   // Only return true if BL is enabled and succeeded on previous run.
   bool success = false;
   if (blacklist_state == BLACKLIST_ENABLED) {
     // If the blacklist succeeded on the previous run reset the failure
     // counter.  Then update the beacon state.
     if (nt::SetRegValueDWORD(key_handle, kBeaconAttemptCount,
                              static_cast<DWORD>(0))) {
       if (nt::SetRegValueDWORD(key_handle, kBeaconState,
                                BLACKLIST_SETUP_RUNNING))
         success = true;
     }
   } else {
     // Some part of the blacklist setup failed last time.  If this has occured
     // blacklist::kBeaconMaxAttempts times in a row we switch the state to
     // failed and skip setting up the blacklist.
     DWORD attempt_count = 0;

     nt::QueryRegValueDWORD(key_handle, blacklist::kBeaconAttemptCount,
                            &attempt_count);
     ++attempt_count;
     nt::SetRegValueDWORD(key_handle, blacklist::kBeaconAttemptCount,
                          attempt_count);

     if (attempt_count >= blacklist::kBeaconMaxAttempts) {
       blacklist_state = blacklist::BLACKLIST_SETUP_FAILED;
       nt::SetRegValueDWORD(key_handle, blacklist::kBeaconState,
                            blacklist_state);
     }
   }

   nt::CloseRegKey(key_handle);
   return success;
 }

 bool ResetBeacon() {
   HANDLE key_handle = INVALID_HANDLE_VALUE;

   if (!nt::CreateRegKey(nt::HKCU, kRegistryBeaconPath,
                         KEY_QUERY_VALUE | KEY_SET_VALUE, &key_handle))
     return false;

   DWORD blacklist_state = BLACKLIST_STATE_MAX;
   if (!nt::QueryRegValueDWORD(key_handle, kBeaconState, &blacklist_state)) {
     nt::CloseRegKey(key_handle);
     return false;
   }

   // Reaching this point with the setup running state means the setup did not
   // crash, so we reset to enabled.  Any other state indicates that setup was
   // skipped; in that case we leave the state alone for later recording.
   if (blacklist_state == BLACKLIST_SETUP_RUNNING) {
     if (!nt::SetRegValueDWORD(key_handle, kBeaconState, BLACKLIST_ENABLED)) {
       nt::CloseRegKey(key_handle);
       return false;
     }
   }

   nt::CloseRegKey(key_handle);
   return true;
 }

 int BlacklistSize() {
   int size = -1;
   while (blacklist::g_troublesome_dlls[++size] != NULL) {
   }

   return size;
 }

 bool IsBlacklistInitialized() {
   return g_blacklist_initialized;
 }

 int GetBlacklistIndex(const wchar_t* dll_name) {
   for (int i = 0;
        i < static_cast<int>(kTroublesomeDllsMaxCount) && g_troublesome_dlls[i];
        ++i) {
     if (_wcsicmp(dll_name, g_troublesome_dlls[i]) == 0)
       return i;
   }
   return -1;
 }

 bool AddDllToBlacklist(const wchar_t* dll_name) {
   int blacklist_size = BlacklistSize();
   // We need to leave one space at the end for the null pointer.
   if (blacklist_size + 1 >= static_cast<int>(kTroublesomeDllsMaxCount))
     return false;
   for (int i = 0; i < blacklist_size; ++i) {
     if (!_wcsicmp(g_troublesome_dlls[i], dll_name))
       return true;
   }

   // Copy string to blacklist.
   wchar_t* str_buffer = new wchar_t[wcslen(dll_name) + 1];
   wcscpy(str_buffer, dll_name);

   g_troublesome_dlls[blacklist_size] = str_buffer;
   g_blocked_dlls[blacklist_size] = false;
   return true;
 }

 bool RemoveDllFromBlacklist(const wchar_t* dll_name) {
   int blacklist_size = BlacklistSize();
   for (int i = 0; i < blacklist_size; ++i) {
     if (!_wcsicmp(g_troublesome_dlls[i], dll_name)) {
       // Found the thing to remove. Delete it then replace it with the last
       // element.
       delete[] g_troublesome_dlls[i];
       g_troublesome_dlls[i] = g_troublesome_dlls[blacklist_size - 1];
       g_troublesome_dlls[blacklist_size - 1] = NULL;

       // Also update the stats recording if we have blocked this dll or not.
       if (g_blocked_dlls[i])
         --g_num_blocked_dlls;
       g_blocked_dlls[i] = g_blocked_dlls[blacklist_size - 1];
       return true;
     }
   }
   return false;
 }

 // TODO(csharp): Maybe store these values in the registry so we can
 // still report them if Chrome crashes early.
 void SuccessfullyBlocked(const wchar_t** blocked_dlls, int* size) {
   if (size == NULL)
     return;

   // If the array isn't valid or big enough, just report the size it needs to
   // be and return.
   if (blocked_dlls == NULL && *size < g_num_blocked_dlls) {
     *size = g_num_blocked_dlls;
     return;
   }

   *size = g_num_blocked_dlls;

   int strings_to_fill = 0;
   for (int i = 0; strings_to_fill < g_num_blocked_dlls && g_troublesome_dlls[i];
        ++i) {
     if (g_blocked_dlls[i]) {
       blocked_dlls[strings_to_fill] = g_troublesome_dlls[i];
       ++strings_to_fill;
     }
   }
 }

 void BlockedDll(size_t blocked_index) {
   assert(blocked_index < kTroublesomeDllsMaxCount);

   if (!g_blocked_dlls[blocked_index] &&
       blocked_index < kTroublesomeDllsMaxCount) {
     ++g_num_blocked_dlls;
     g_blocked_dlls[blocked_index] = true;
   }
 }

 bool Initialize(bool force) {
   // Check to see that we found the functions we need in ntdll.
   if (!InitializeInterceptImports())
     return false;

   // Check to see if this is a non-browser process, abort if so.
   if (install_static::IsNonBrowserProcess())
     return false;

   // Check to see if the blacklist beacon is still set to running (indicating a
   // failure) or disabled, and abort if so.
   if (!force && !LeaveSetupBeacon())
     return false;

   // It is possible for other dlls to have already patched code by now and
   // attempting to patch their code might result in crashes.
   const bool kRelaxed = false;

   // Create a thunk via the appropriate ServiceResolver instance.
   sandbox::ServiceResolverThunk* thunk = elf_hook::HookSystemService(kRelaxed);

   // Don't try blacklisting on unsupported OS versions.
   if (!thunk)
     return false;

   BYTE* thunk_storage = reinterpret_cast<BYTE*>(&g_thunk_storage);

   // Mark the thunk storage as readable and writeable, since we
   // ready to write to it.
   DWORD old_protect = 0;
   if (!VirtualProtect(&g_thunk_storage, sizeof(g_thunk_storage),
                       PAGE_EXECUTE_READWRITE, &old_protect)) {
     return false;
   }

   thunk->AllowLocalPatches();

   // We declare this early so it can be used in the 64-bit block below and
   // still work on 32-bit build when referenced at the end of the function.
   BOOL page_executable = false;

 // Replace the default NtMapViewOfSection with our patched version.
 #if defined(_WIN64)
   NTSTATUS ret =
       thunk->Setup(::GetModuleHandle(sandbox::kNtdllName),
                    reinterpret_cast<void*>(&__ImageBase), "NtMapViewOfSection",
                    NULL, &blacklist::BlNtMapViewOfSection64, thunk_storage,
                    sizeof(sandbox::ThunkData), NULL);

   // Keep a pointer to the original code, we don't have enough space to
   // add it directly to the call.
   g_nt_map_view_of_section_func =
       reinterpret_cast<NtMapViewOfSectionFunction>(thunk_storage);

   // Ensure that the pointer to the old function can't be changed.
   page_executable = VirtualProtect(&g_nt_map_view_of_section_func,
                                    sizeof(g_nt_map_view_of_section_func),
                                    PAGE_EXECUTE_READ, &old_protect);
 #else
   NTSTATUS ret =
       thunk->Setup(::GetModuleHandle(sandbox::kNtdllName),
                    reinterpret_cast<void*>(&__ImageBase), "NtMapViewOfSection",
                    NULL, &blacklist::BlNtMapViewOfSection, thunk_storage,
                    sizeof(sandbox::ThunkData), NULL);
 #endif
   delete thunk;

   // Record if we have initialized the blacklist.
   g_blacklist_initialized = NT_SUCCESS(ret);

   // Mark the thunk storage as executable and prevent any future writes to it.
   page_executable = page_executable &&
                     VirtualProtect(&g_thunk_storage, sizeof(g_thunk_storage),
                                    PAGE_EXECUTE_READ, &old_protect);

   return NT_SUCCESS(ret) && page_executable;
 }

 }  // namespace blacklist
	// Copyright 2013 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.

	#include "chrome_elf/blacklist/blacklist.h"

	#include <assert.h>
	#include <string.h>

	#include <vector>

	#include "chrome/install_static/install_util.h"
	#include "chrome_elf/blacklist/blacklist_interceptions.h"
	#include "chrome_elf/chrome_elf_constants.h"
	#include "chrome_elf/hook_util/hook_util.h"
	#include "chrome_elf/nt_registry/nt_registry.h"
	#include "sandbox/win/src/interception_internal.h"
	#include "sandbox/win/src/internal_types.h"
	#include "sandbox/win/src/service_resolver.h"

	// http://blogs.msdn.com/oldnewthing/archive/2004/10/25/247180.aspx
	extern "C" IMAGE_DOS_HEADER __ImageBase;

	namespace blacklist {

	// The DLLs listed here are known (or under strong suspicion) of causing crashes
	// when they are loaded in the browser. DLLs should only be added to this list
	// if there is nothing else Chrome can do to prevent those crashes.
	// For more information about how this list is generated, and how to get off
	// of it, see:
	// https://sites.google.com/a/chromium.org/dev/Home/third-party-developers
	// NOTE: Please remember to update the DllHash enum in histograms.xml when
	// adding a new value to the blacklist.
	const wchar_t* g_troublesome_dlls[kTroublesomeDllsMaxCount] = {
	L"949ba8b6a9.dll", // Coupon Time.
	L"activedetect32.dll", // Lenovo One Key Theater.
	// See crbug.com/379218.
	L"activedetect64.dll", // Lenovo One Key Theater.
	L"bitguard.dll", // Unknown (suspected malware).
	L"bsvc.dll", // Unknown (suspected adware).
	L"chrmxtn.dll", // Unknown (keystroke logger).
	L"cplushook.dll", // Unknown (suspected malware).
	L"crdli.dll", // Linkury Inc.
	L"crdli64.dll", // Linkury Inc.
	L"datamngr.dll", // Unknown (suspected adware).
	L"dpinterface32.dll", // Unknown (suspected adware).
	L"explorerex.dll", // Unknown (suspected adware).
	L"hk.dll", // Unknown (keystroke logger).
	L"libapi2hook.dll", // V-Bates.
	L"libinject.dll", // V-Bates.
	L"libinject2.dll", // V-Bates.
	L"libredir2.dll", // V-Bates.
	L"libsvn_tsvn32.dll", // TortoiseSVN.
	L"libwinhook.dll", // V-Bates.
	L"lmrn.dll", // Unknown.
	L"minisp.dll", // Unknown (suspected malware).
	L"minisp32.dll", // Unknown (suspected malware).
	L"offerswizarddll.dll", // Unknown (suspected adware).
	L"safetynut.dll", // Unknown (suspected adware).
	L"smdmf.dll", // Unknown (suspected adware).
	L"spappsv32.dll", // Unknown (suspected adware).
	L"systemk.dll", // Unknown (suspected adware).
	L"vntsrv.dll", // Virtual New Tab by APN LLC.
	L"wajam_goblin_64.dll", // Wajam Internet Technologies.
	L"wajam_goblin.dll", // Wajam Internet Technologies.
	L"windowsapihookdll32.dll", // Lenovo One Key Theater.
	// See crbug.com/379218.
	L"windowsapihookdll64.dll", // Lenovo One Key Theater.
	L"virtualcamera.ax", // %PROGRAMFILES%\ASUS\VirtualCamera.
	// See crbug.com/422522.
	L"ycwebcamerasource.ax", // CyberLink Youcam, crbug.com/424159
	// Keep this null pointer here to mark the end of the list.
	NULL,
	};

	bool g_blocked_dlls[kTroublesomeDllsMaxCount] = {};
	int g_num_blocked_dlls = 0;

	} // namespace blacklist

	// Allocate storage for thunks in a page of this module to save on doing
	// an extra allocation at run time.
	#pragma section(".crthunk", read, execute)
	__declspec(allocate(".crthunk")) sandbox::ThunkData g_thunk_storage;

	namespace {

	// Record if the blacklist was successfully initialized so processes can easily
	// determine if the blacklist is enabled for them.
	bool g_blacklist_initialized = false;

	} // namespace

	namespace blacklist {

	#if defined(_WIN64)
	// Allocate storage for the pointer to the old NtMapViewOfSectionFunction.
	#pragma section(".oldntmap", write, read)
	__declspec(allocate(".oldntmap"))
	NtMapViewOfSectionFunction g_nt_map_view_of_section_func = NULL;
	#endif

	bool LeaveSetupBeacon() {
	HANDLE key_handle = INVALID_HANDLE_VALUE;

	if (!nt::CreateRegKey(nt::HKCU, kRegistryBeaconPath,
	KEY_QUERY_VALUE \| KEY_SET_VALUE, &key_handle))
	return false;

	DWORD blacklist_state = BLACKLIST_STATE_MAX;
	if (!nt::QueryRegValueDWORD(key_handle, kBeaconState, &blacklist_state) \|\|
	blacklist_state == BLACKLIST_DISABLED) {
	nt::CloseRegKey(key_handle);
	return false;
	}

	// Handle attempt count.
	// Only return true if BL is enabled and succeeded on previous run.
	bool success = false;
	if (blacklist_state == BLACKLIST_ENABLED) {
	// If the blacklist succeeded on the previous run reset the failure
	// counter. Then update the beacon state.
	if (nt::SetRegValueDWORD(key_handle, kBeaconAttemptCount,
	static_cast<DWORD>(0))) {
	if (nt::SetRegValueDWORD(key_handle, kBeaconState,
	BLACKLIST_SETUP_RUNNING))
	success = true;
	}
	} else {
	// Some part of the blacklist setup failed last time. If this has occured
	// blacklist::kBeaconMaxAttempts times in a row we switch the state to
	// failed and skip setting up the blacklist.
	DWORD attempt_count = 0;

	nt::QueryRegValueDWORD(key_handle, blacklist::kBeaconAttemptCount,
	&attempt_count);
	++attempt_count;
	nt::SetRegValueDWORD(key_handle, blacklist::kBeaconAttemptCount,
	attempt_count);

	if (attempt_count >= blacklist::kBeaconMaxAttempts) {
	blacklist_state = blacklist::BLACKLIST_SETUP_FAILED;
	nt::SetRegValueDWORD(key_handle, blacklist::kBeaconState,
	blacklist_state);
	}
	}

	nt::CloseRegKey(key_handle);
	return success;
	}

	bool ResetBeacon() {
	HANDLE key_handle = INVALID_HANDLE_VALUE;

	if (!nt::CreateRegKey(nt::HKCU, kRegistryBeaconPath,
	KEY_QUERY_VALUE \| KEY_SET_VALUE, &key_handle))
	return false;

	DWORD blacklist_state = BLACKLIST_STATE_MAX;
	if (!nt::QueryRegValueDWORD(key_handle, kBeaconState, &blacklist_state)) {
	nt::CloseRegKey(key_handle);
	return false;
	}

	// Reaching this point with the setup running state means the setup did not
	// crash, so we reset to enabled. Any other state indicates that setup was
	// skipped; in that case we leave the state alone for later recording.
	if (blacklist_state == BLACKLIST_SETUP_RUNNING) {
	if (!nt::SetRegValueDWORD(key_handle, kBeaconState, BLACKLIST_ENABLED)) {
	nt::CloseRegKey(key_handle);
	return false;
	}
	}

	nt::CloseRegKey(key_handle);
	return true;
	}

	int BlacklistSize() {
	int size = -1;
	while (blacklist::g_troublesome_dlls[++size] != NULL) {
	}

	return size;
	}

	bool IsBlacklistInitialized() {
	return g_blacklist_initialized;
	}

	int GetBlacklistIndex(const wchar_t* dll_name) {
	for (int i = 0;
	i < static_cast<int>(kTroublesomeDllsMaxCount) && g_troublesome_dlls[i];
	++i) {
	if (_wcsicmp(dll_name, g_troublesome_dlls[i]) == 0)
	return i;
	}
	return -1;
	}

	bool AddDllToBlacklist(const wchar_t* dll_name) {
	int blacklist_size = BlacklistSize();
	// We need to leave one space at the end for the null pointer.
	if (blacklist_size + 1 >= static_cast<int>(kTroublesomeDllsMaxCount))
	return false;
	for (int i = 0; i < blacklist_size; ++i) {
	if (!_wcsicmp(g_troublesome_dlls[i], dll_name))
	return true;
	}

	// Copy string to blacklist.
	wchar_t* str_buffer = new wchar_t[wcslen(dll_name) + 1];
	wcscpy(str_buffer, dll_name);

	g_troublesome_dlls[blacklist_size] = str_buffer;
	g_blocked_dlls[blacklist_size] = false;
	return true;
	}

	bool RemoveDllFromBlacklist(const wchar_t* dll_name) {
	int blacklist_size = BlacklistSize();
	for (int i = 0; i < blacklist_size; ++i) {
	if (!_wcsicmp(g_troublesome_dlls[i], dll_name)) {
	// Found the thing to remove. Delete it then replace it with the last
	// element.
	delete[] g_troublesome_dlls[i];
	g_troublesome_dlls[i] = g_troublesome_dlls[blacklist_size - 1];
	g_troublesome_dlls[blacklist_size - 1] = NULL;

	// Also update the stats recording if we have blocked this dll or not.
	if (g_blocked_dlls[i])
	--g_num_blocked_dlls;
	g_blocked_dlls[i] = g_blocked_dlls[blacklist_size - 1];
	return true;
	}
	}
	return false;
	}

	// TODO(csharp): Maybe store these values in the registry so we can
	// still report them if Chrome crashes early.
	void SuccessfullyBlocked(const wchar_t** blocked_dlls, int* size) {
	if (size == NULL)
	return;

	// If the array isn't valid or big enough, just report the size it needs to
	// be and return.
	if (blocked_dlls == NULL && *size < g_num_blocked_dlls) {
	*size = g_num_blocked_dlls;
	return;
	}

	*size = g_num_blocked_dlls;

	int strings_to_fill = 0;
	for (int i = 0; strings_to_fill < g_num_blocked_dlls && g_troublesome_dlls[i];
	++i) {
	if (g_blocked_dlls[i]) {
	blocked_dlls[strings_to_fill] = g_troublesome_dlls[i];
	++strings_to_fill;
	}
	}
	}

	void BlockedDll(size_t blocked_index) {
	assert(blocked_index < kTroublesomeDllsMaxCount);

	if (!g_blocked_dlls[blocked_index] &&
	blocked_index < kTroublesomeDllsMaxCount) {
	++g_num_blocked_dlls;
	g_blocked_dlls[blocked_index] = true;
	}
	}

	bool Initialize(bool force) {
	// Check to see that we found the functions we need in ntdll.
	if (!InitializeInterceptImports())
	return false;

	// Check to see if this is a non-browser process, abort if so.
	if (install_static::IsNonBrowserProcess())
	return false;

	// Check to see if the blacklist beacon is still set to running (indicating a
	// failure) or disabled, and abort if so.
	if (!force && !LeaveSetupBeacon())
	return false;

	// It is possible for other dlls to have already patched code by now and
	// attempting to patch their code might result in crashes.
	const bool kRelaxed = false;

	// Create a thunk via the appropriate ServiceResolver instance.
	sandbox::ServiceResolverThunk* thunk = elf_hook::HookSystemService(kRelaxed);

	// Don't try blacklisting on unsupported OS versions.
	if (!thunk)
	return false;

	BYTE* thunk_storage = reinterpret_cast<BYTE*>(&g_thunk_storage);

	// Mark the thunk storage as readable and writeable, since we
	// ready to write to it.
	DWORD old_protect = 0;
	if (!VirtualProtect(&g_thunk_storage, sizeof(g_thunk_storage),
	PAGE_EXECUTE_READWRITE, &old_protect)) {
	return false;
	}

	thunk->AllowLocalPatches();

	// We declare this early so it can be used in the 64-bit block below and
	// still work on 32-bit build when referenced at the end of the function.
	BOOL page_executable = false;

	// Replace the default NtMapViewOfSection with our patched version.
	#if defined(_WIN64)
	NTSTATUS ret =
	thunk->Setup(::GetModuleHandle(sandbox::kNtdllName),
	reinterpret_cast<void*>(&__ImageBase), "NtMapViewOfSection",
	NULL, &blacklist::BlNtMapViewOfSection64, thunk_storage,
	sizeof(sandbox::ThunkData), NULL);

	// Keep a pointer to the original code, we don't have enough space to
	// add it directly to the call.
	g_nt_map_view_of_section_func =
	reinterpret_cast<NtMapViewOfSectionFunction>(thunk_storage);

	// Ensure that the pointer to the old function can't be changed.
	page_executable = VirtualProtect(&g_nt_map_view_of_section_func,
	sizeof(g_nt_map_view_of_section_func),
	PAGE_EXECUTE_READ, &old_protect);
	#else
	NTSTATUS ret =
	thunk->Setup(::GetModuleHandle(sandbox::kNtdllName),
	reinterpret_cast<void*>(&__ImageBase), "NtMapViewOfSection",
	NULL, &blacklist::BlNtMapViewOfSection, thunk_storage,
	sizeof(sandbox::ThunkData), NULL);
	#endif
	delete thunk;

	// Record if we have initialized the blacklist.
	g_blacklist_initialized = NT_SUCCESS(ret);

	// Mark the thunk storage as executable and prevent any future writes to it.
	page_executable = page_executable &&
	VirtualProtect(&g_thunk_storage, sizeof(g_thunk_storage),
	PAGE_EXECUTE_READ, &old_protect);

	return NT_SUCCESS(ret) && page_executable;
	}

	} // namespace blacklist