From 850b25389efc84722289cac5c385c833a723b847 Mon Sep 17 00:00:00 2001
From: David Major <dmajor@mozilla.com>
Date: Wed, 1 Feb 2017 10:52:13 +1300
Subject: [PATCH] Bug 1335163 - Remove the now-unused XPCOM ASLR checks in the
 DLL blocklist. r=bsmedberg

MozReview-Commit-ID: 2iY5g72d4xg

--HG--
extra : rebase_source : 309eb59fe0a98f0a4dfd384b3028a0ec107220c5
---
 mozglue/build/WindowsDllBlocklist.cpp | 62 ---------------------------
 mozglue/build/WindowsDllBlocklist.h   | 19 +-------
 2 files changed, 1 insertion(+), 80 deletions(-)

diff --git a/mozglue/build/WindowsDllBlocklist.cpp b/mozglue/build/WindowsDllBlocklist.cpp
index 01ad2654e070..41ee87f7fe01 100644
--- a/mozglue/build/WindowsDllBlocklist.cpp
+++ b/mozglue/build/WindowsDllBlocklist.cpp
@@ -244,7 +244,6 @@ static const char kUser32BeforeBlocklistParameter[] = "User32BeforeBlocklist=1\n
 static const int kUser32BeforeBlocklistParameterLen =
   sizeof(kUser32BeforeBlocklistParameter) - 1;
 
-static DWORD sThreadLoadingXPCOMModule;
 static bool sBlocklistInitAttempted;
 static bool sBlocklistInitFailed;
 static bool sUser32BeforeBlocklist;
@@ -309,41 +308,6 @@ private:
   void* mRealView;
 };
 
-bool
-CheckASLR(const wchar_t* path)
-{
-  bool retval = false;
-
-  HANDLE file = ::CreateFileW(path, GENERIC_READ, FILE_SHARE_READ,
-                              nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL,
-                              nullptr);
-  if (file != INVALID_HANDLE_VALUE) {
-    HANDLE map = ::CreateFileMappingW(file, nullptr, PAGE_READONLY, 0, 0,
-                                      nullptr);
-    if (map) {
-      RVAMap<IMAGE_DOS_HEADER> peHeader(map, 0);
-      if (peHeader) {
-        RVAMap<IMAGE_NT_HEADERS> ntHeader(map, peHeader->e_lfanew);
-        if (ntHeader) {
-          // If the DLL has no code, permit it regardless of ASLR status.
-          if (ntHeader->OptionalHeader.SizeOfCode == 0) {
-            retval = true;
-          }
-          // Check to see if the DLL supports ASLR
-          else if ((ntHeader->OptionalHeader.DllCharacteristics &
-                    IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE) != 0) {
-            retval = true;
-          }
-        }
-      }
-      ::CloseHandle(map);
-    }
-    ::CloseHandle(file);
-  }
-
-  return retval;
-}
-
 DWORD
 GetTimestamp(const wchar_t* path)
 {
@@ -727,21 +691,6 @@ continue_loading:
   printf_stderr("LdrLoadDll: continuing load... ('%S')\n", moduleFileName->Buffer);
 #endif
 
-  if (GetCurrentThreadId() == sThreadLoadingXPCOMModule) {
-    // Check to ensure that the DLL has ASLR.
-    full_fname = getFullPath(filePath, fname);
-    if (!full_fname) {
-      // uh, we couldn't find the DLL at all, so...
-      printf_stderr("LdrLoadDll: Blocking load of '%s' (SearchPathW didn't find it?)\n", dllName);
-      return STATUS_DLL_NOT_FOUND;
-    }
-
-    if (!CheckASLR(full_fname.get())) {
-      printf_stderr("LdrLoadDll: Blocking load of '%s'.  XPCOM components must support ASLR.\n", dllName);
-      return STATUS_DLL_NOT_FOUND;
-    }
-  }
-
   return stub_LdrLoadDll(filePath, flags, moduleFileName, handle);
 }
 
@@ -783,17 +732,6 @@ DllBlocklist_Initialize()
   }
 }
 
-MFBT_API void
-DllBlocklist_SetInXPCOMLoadOnMainThread(bool inXPCOMLoadOnMainThread)
-{
-  if (inXPCOMLoadOnMainThread) {
-    MOZ_ASSERT(sThreadLoadingXPCOMModule == 0, "Only one thread should be doing this");
-    sThreadLoadingXPCOMModule = GetCurrentThreadId();
-  } else {
-    sThreadLoadingXPCOMModule = 0;
-  }
-}
-
 MFBT_API void
 DllBlocklist_WriteNotes(HANDLE file)
 {
diff --git a/mozglue/build/WindowsDllBlocklist.h b/mozglue/build/WindowsDllBlocklist.h
index 2e6686cbd747..ad8944dcc278 100644
--- a/mozglue/build/WindowsDllBlocklist.h
+++ b/mozglue/build/WindowsDllBlocklist.h
@@ -9,31 +9,14 @@
 #if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
 
 #include <windows.h>
-#include "mozilla/GuardObjects.h"
 #include "mozilla/Attributes.h"
+#include "mozilla/Types.h"
 
 #define HAS_DLL_BLOCKLIST
 
 MFBT_API void DllBlocklist_Initialize();
-MFBT_API void DllBlocklist_SetInXPCOMLoadOnMainThread(bool inXPCOMLoadOnMainThread);
 MFBT_API void DllBlocklist_WriteNotes(HANDLE file);
 MFBT_API bool DllBlocklist_CheckStatus();
 
-class MOZ_RAII AutoSetXPCOMLoadOnMainThread
-{
-  public:
-    explicit AutoSetXPCOMLoadOnMainThread(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM) {
-      MOZ_GUARD_OBJECT_NOTIFIER_INIT;
-      DllBlocklist_SetInXPCOMLoadOnMainThread(true);
-    }
-
-    ~AutoSetXPCOMLoadOnMainThread() {
-      DllBlocklist_SetInXPCOMLoadOnMainThread(false);
-    }
-
-  private:
-    MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
-};
-
 #endif // defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64))
 #endif // mozilla_windowsdllblocklist_h