[Windows Sandbox] MITIGATION_EXTENSION_POINT_DISABLE support for children.

sandbox/win/tests/integration_tests/hooking_dll.cc

Index: sandbox/win/tests/integration_tests/hooking_dll.cc
diff --git a/sandbox/win/tests/integration_tests/hooking_dll.cc b/sandbox/win/tests/integration_tests/hooking_dll.cc
new file mode 100644
index 0000000000000000000000000000000000000000..d100d254b8131fea5d97384d134d7636e8b5d1fb
--- /dev/null
+++ b/sandbox/win/tests/integration_tests/hooking_dll.cc
@@ -0,0 +1,28 @@
+// Copyright (c) 2016 The Chromium Authors. All rights reserved.

[Will Harris, 2016/04/04 00:15:09]

no (c)

[penny, 2016/04/11 22:11:59]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <windows.h>
+#include <stdio.h>
+
+#pragma data_seg(".shared")
+BOOL hook_called = false;

[Will Harris, 2016/04/04 00:15:09]

why is this linker-fu needed?

[penny, 2016/04/11 22:11:59]

Fair question.  I've added some detailed comments.

This makes a segment that is shared/accessible by every instance of the DLL
(mapped into many processes for hooks).  When I check whether "WasHookCalled()"
in the test process, I'm actually calling into the version of the DLL in the
test process - but I need the information from the version of the DLL that's in
the separate WinProc address!  This allows me to do so.  Hook DLLs generally
require some variables to be in a section like this for management.

I wanted to add a cool little image to help visualize this, but no way to insert
images in these reviews.

+#pragma data_seg()
+#pragma comment(linker, "/SECTION:.shared,RWS")
+
+extern "C" __declspec(dllexport) BOOL WasHookCalled() {
+  return hook_called;
+}
+
+extern "C" __declspec(dllexport) LRESULT
+    HookProc(int code, WPARAM wParam, LPARAM lParam) {
+  // Supported versions of Windows do not require the HHOOK to be passed along.
+  hook_called = true;
+  return CallNextHookEx(NULL, code, wParam, lParam);
+}
+
+BOOL WINAPI DllMain(__in HINSTANCE hinstDLL,
+                    __in DWORD reason,
+                    __in LPVOID lpvReserved) {
+  return TRUE;
+}