The Tor Browser: mozglue/build/WindowsDllBlocklist.cpp@97036ab72558 (annotated)

mozglue/build/WindowsDllBlocklist.cpp@97036ab72558 (annotated)

mozglue/build/WindowsDllBlocklist.cpp

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 /* -*- Mode: C++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include <windows.h>
 #include <winternl.h>
 #include <io.h>
 #pragma warning( push )
 #pragma warning( disable : 4275 4530 ) // See msvc-stl-wrapper.template.h
 #include <map>
 #pragma warning( pop )
 #define MOZ_NO_MOZALLOC
 #include "nsAutoPtr.h"
 #include "nsWindowsDllInterceptor.h"
 #include "mozilla/WindowsVersion.h"
 #include "nsWindowsHelpers.h"
 using namespace mozilla;
 #define ALL_VERSIONS   ((unsigned long long)-1LL)
 // DLLs sometimes ship without a version number, particularly early
 // releases. Blocking "version <= 0" has the effect of blocking unversioned
 // DLLs (since the call to get version info fails), but not blocking
 // any versioned instance.
 #define UNVERSIONED    ((unsigned long long)0LL)
 // Convert the 4 (decimal) components of a DLL version number into a
 // single unsigned long long, as needed by the blocklist
 #define MAKE_VERSION(a,b,c,d)\
   ((a##ULL << 48) + (b##ULL << 32) + (c##ULL << 16) + d##ULL)
 struct DllBlockInfo {
   // The name of the DLL -- in LOWERCASE!  It will be compared to
   // a lowercase version of the DLL name only.
   const char *name;
   // If maxVersion is ALL_VERSIONS, we'll block all versions of this
   // dll.  Otherwise, we'll block all versions less than or equal to
   // the given version, as queried by GetFileVersionInfo and
   // VS_FIXEDFILEINFO's dwFileVersionMS and dwFileVersionLS fields.
   //
   // Note that the version is usually 4 components, which is A.B.C.D
   // encoded as 0x AAAA BBBB CCCC DDDD ULL (spaces added for clarity),
   // but it's not required to be of that format.
   //
   // If the USE_TIMESTAMP flag is set, then we use the timestamp from
   // the IMAGE_FILE_HEADER in lieu of a version number.
   unsigned long long maxVersion;
   enum {
     FLAGS_DEFAULT = 0,
     BLOCK_WIN8PLUS_ONLY = 1,
     BLOCK_XP_ONLY = 2,
     USE_TIMESTAMP = 4,
   } flags;
 };
 static DllBlockInfo sWindowsDllBlocklist[] = {
   // EXAMPLE:
   // { "uxtheme.dll", ALL_VERSIONS },
   // { "uxtheme.dll", 0x0000123400000000ULL },
   // The DLL name must be in lowercase!
   // NPFFAddon - Known malware
   { "npffaddon.dll", ALL_VERSIONS},
   // AVG 8 - Antivirus vendor AVG, old version, plugin already blocklisted
   {"avgrsstx.dll", MAKE_VERSION(8,5,0,401)},
   // calc.dll - Suspected malware
   {"calc.dll", MAKE_VERSION(1,0,0,1)},
   // hook.dll - Suspected malware
   {"hook.dll", ALL_VERSIONS},
   // GoogleDesktopNetwork3.dll - Extremely old, unversioned instances
   // of this DLL cause crashes
   {"googledesktopnetwork3.dll", UNVERSIONED},
   // rdolib.dll - Suspected malware
   {"rdolib.dll", MAKE_VERSION(6,0,88,4)},
   // fgjk4wvb.dll - Suspected malware
   {"fgjk4wvb.dll", MAKE_VERSION(8,8,8,8)},
   // radhslib.dll - Naomi internet filter - unmaintained since 2006
   {"radhslib.dll", UNVERSIONED},
   // Music download filter for vkontakte.ru - old instances
   // of this DLL cause crashes
   {"vksaver.dll", MAKE_VERSION(2,2,2,0)},
   // Topcrash in Firefox 4.0b1
   {"rlxf.dll", MAKE_VERSION(1,2,323,1)},
   // psicon.dll - Topcrashes in Thunderbird, and some crashes in Firefox
   // Adobe photoshop library, now redundant in later installations
   {"psicon.dll", ALL_VERSIONS},
   // Topcrash in Firefox 4 betas (bug 618899)
   {"accelerator.dll", MAKE_VERSION(3,2,1,6)},
   // Topcrash with Roboform in Firefox 8 (bug 699134)
   {"rf-firefox.dll", MAKE_VERSION(7,6,1,0)},
   {"roboform.dll", MAKE_VERSION(7,6,1,0)},
   // Topcrash with Babylon Toolbar on FF16+ (bug 721264)
   {"babyfox.dll", ALL_VERSIONS},
   // sprotector.dll crashes, bug 957258
   {"sprotector.dll", ALL_VERSIONS},
   // Topcrash with Websense Endpoint, bug 828184
   {"qipcap.dll", MAKE_VERSION(7, 6, 815, 1)},
   // leave these two in always for tests
   { "mozdllblockingtest.dll", ALL_VERSIONS },
   { "mozdllblockingtest_versioned.dll", 0x0000000400000000ULL },
   // Windows Media Foundation FLAC decoder and type sniffer (bug 839031).
   { "mfflac.dll", ALL_VERSIONS },
   // Older Relevant Knowledge DLLs cause us to crash (bug 904001).
   { "rlnx.dll", MAKE_VERSION(1, 3, 334, 9) },
   { "pmnx.dll", MAKE_VERSION(1, 3, 334, 9) },
   { "opnx.dll", MAKE_VERSION(1, 3, 334, 9) },
   { "prnx.dll", MAKE_VERSION(1, 3, 334, 9) },
   // Older belgian ID card software causes Firefox to crash or hang on
   // shutdown, bug 831285 and 918399.
   { "beid35cardlayer.dll", MAKE_VERSION(3, 5, 6, 6968) },
   // bug 925459, bitguard crashes
   { "bitguard.dll", ALL_VERSIONS },
   // bug 812683 - crashes in Windows library when Asus Gamer OSD is installed
   // Software is discontinued/unsupported
   { "atkdx11disp.dll", ALL_VERSIONS },
   // Topcrash with Conduit SearchProtect, bug 944542
   { "spvc32.dll", ALL_VERSIONS },
   // XP topcrash with F-Secure, bug 970362
   { "fs_ccf_ni_umh32.dll", MAKE_VERSION(1, 42, 101, 0), DllBlockInfo::BLOCK_XP_ONLY },
   // Topcrash with V-bates, bug 1002748 and bug 1023239
   { "libinject.dll", UNVERSIONED },
   { "libinject2.dll", 0x537DDC93, DllBlockInfo::USE_TIMESTAMP },
   { "libredir2.dll", 0x5385B7ED, DllBlockInfo::USE_TIMESTAMP },
   // Crashes with RoboForm2Go written against old SDK, bug 988311
   { "rf-firefox-22.dll", ALL_VERSIONS },
   { nullptr, 0 }
 };
 #ifndef STATUS_DLL_NOT_FOUND
 #define STATUS_DLL_NOT_FOUND ((DWORD)0xC0000135L)
 #endif
 // define this for very verbose dll load debug spew
 #undef DEBUG_very_verbose
 static const char kBlockedDllsParameter[] = "BlockedDllList=";
 static const int kBlockedDllsParameterLen =
   sizeof(kBlockedDllsParameter) - 1;
 static const char kBlocklistInitFailedParameter[] = "BlocklistInitFailed=1\n";
 static const int kBlocklistInitFailedParameterLen =
   sizeof(kBlocklistInitFailedParameter) - 1;
 static const char kUser32BeforeBlocklistParameter[] = "User32BeforeBlocklist=1\n";
 static const int kUser32BeforeBlocklistParameterLen =
   sizeof(kUser32BeforeBlocklistParameter) - 1;
 static DWORD sThreadLoadingXPCOMModule;
 static bool sBlocklistInitFailed;
 static bool sUser32BeforeBlocklist;
 // Duplicated from xpcom glue. Ideally this should be shared.
 void
 printf_stderr(const char *fmt, ...)
 {
   if (IsDebuggerPresent()) {
     char buf[2048];
     va_list args;
     va_start(args, fmt);
     vsnprintf(buf, sizeof(buf), fmt, args);
     buf[sizeof(buf) - 1] = '\0';
     va_end(args);
     OutputDebugStringA(buf);
   }
   FILE *fp = _fdopen(_dup(2), "a");
   if (!fp)
       return;
   va_list args;
   va_start(args, fmt);
   vfprintf(fp, fmt, args);
   va_end(args);
   fclose(fp);
 }
 namespace {
 typedef NTSTATUS (NTAPI *LdrLoadDll_func) (PWCHAR filePath, PULONG flags, PUNICODE_STRING moduleFileName, PHANDLE handle);
 static LdrLoadDll_func stub_LdrLoadDll = 0;
 template <class T>
 struct RVAMap {
   RVAMap(HANDLE map, DWORD offset) {
     SYSTEM_INFO info;
     GetSystemInfo(&info);
     DWORD alignedOffset = (offset / info.dwAllocationGranularity) *
                           info.dwAllocationGranularity;
     MOZ_ASSERT(offset - alignedOffset < info.dwAllocationGranularity, "Wtf");
     mRealView = ::MapViewOfFile(map, FILE_MAP_READ, 0, alignedOffset,
                                 sizeof(T) + (offset - alignedOffset));
     mMappedView = mRealView ? reinterpret_cast<T*>((char*)mRealView + (offset - alignedOffset)) :
                               nullptr;
   }
   ~RVAMap() {
     if (mRealView) {
       ::UnmapViewOfFile(mRealView);
     }
   }
   operator const T*() const { return mMappedView; }
   const T* operator->() const { return mMappedView; }
 private:
   const T* mMappedView;
   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)
 {
   DWORD timestamp = 0;
   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) {
           timestamp = ntHeader->FileHeader.TimeDateStamp;
         }
       }
       ::CloseHandle(map);
     }
     ::CloseHandle(file);
   }
   return timestamp;
 }
 // This lock protects both the reentrancy sentinel and the crash reporter
 // data structures.
 static CRITICAL_SECTION sLock;
 /**
  * Some versions of Windows call LoadLibraryEx to get the version information
  * for a DLL, which causes our patched LdrLoadDll implementation to re-enter
  * itself and cause infinite recursion and a stack-exhaustion crash. We protect
  * against reentrancy by allowing recursive loads of the same DLL.
  *
  * Note that we don't use __declspec(thread) because that doesn't work in DLLs
  * loaded via LoadLibrary and there can be a limited number of TLS slots, so
  * we roll our own.
  */
 class ReentrancySentinel
 {
 public:
   explicit ReentrancySentinel(const char* dllName)
   {
     DWORD currentThreadId = GetCurrentThreadId();
     AutoCriticalSection lock(&sLock);
     mPreviousDllName = (*sThreadMap)[currentThreadId];
     // If there is a DLL currently being loaded and it has the same name
     // as the current attempt, we're re-entering.
     mReentered = mPreviousDllName && !stricmp(mPreviousDllName, dllName);
     (*sThreadMap)[currentThreadId] = dllName;
   }
   ~ReentrancySentinel()
   {
     DWORD currentThreadId = GetCurrentThreadId();
     AutoCriticalSection lock(&sLock);
     (*sThreadMap)[currentThreadId] = mPreviousDllName;
   }
   bool BailOut() const
   {
     return mReentered;
   };
   static void InitializeStatics()
   {
     InitializeCriticalSection(&sLock);
     sThreadMap = new std::map<DWORD, const char*>;
   }
 private:
   static std::map<DWORD, const char*>* sThreadMap;
   const char* mPreviousDllName;
   bool mReentered;
 };
 std::map<DWORD, const char*>* ReentrancySentinel::sThreadMap;
 /**
  * This is a linked list of DLLs that have been blocked. It doesn't use
  * mozilla::LinkedList because this is an append-only list and doesn't need
  * to be doubly linked.
  */
 class DllBlockSet
 {
 public:
   static void Add(const char* name, unsigned long long version);
   // Write the list of blocked DLLs to a file HANDLE. This method is run after
   // a crash occurs and must therefore not use the heap, etc.
   static void Write(HANDLE file);
 private:
   DllBlockSet(const char* name, unsigned long long version)
     : mName(name)
     , mVersion(version)
     , mNext(nullptr)
   {
   }
   const char* mName; // points into the sWindowsDllBlocklist string
   unsigned long long mVersion;
   DllBlockSet* mNext;
   static DllBlockSet* gFirst;
 };
 DllBlockSet* DllBlockSet::gFirst;
 void
 DllBlockSet::Add(const char* name, unsigned long long version)
 {
   AutoCriticalSection lock(&sLock);
   for (DllBlockSet* b = gFirst; b; b = b->mNext) {
     if (0 == strcmp(b->mName, name) && b->mVersion == version) {
       return;
     }
   }
   // Not already present
   DllBlockSet* n = new DllBlockSet(name, version);
   n->mNext = gFirst;
   gFirst = n;
 }
 void
 DllBlockSet::Write(HANDLE file)
 {
   AutoCriticalSection lock(&sLock);
   DWORD nBytes;
   // Because this method is called after a crash occurs, and uses heap memory,
   // protect this entire block with a structured exception handler.
   MOZ_SEH_TRY {
     for (DllBlockSet* b = gFirst; b; b = b->mNext) {
       // write name[,v.v.v.v];
       WriteFile(file, b->mName, strlen(b->mName), &nBytes, nullptr);
       if (b->mVersion != -1) {
         WriteFile(file, ",", 1, &nBytes, nullptr);
         uint16_t parts[4];
         parts[0] = b->mVersion >> 48;
         parts[1] = (b->mVersion >> 32) & 0xFFFF;
         parts[2] = (b->mVersion >> 16) & 0xFFFF;
         parts[3] = b->mVersion & 0xFFFF;
         for (int p = 0; p < 4; ++p) {
           char buf[32];
           ltoa(parts[p], buf, 10);
           WriteFile(file, buf, strlen(buf), &nBytes, nullptr);
           if (p != 3) {
             WriteFile(file, ".", 1, &nBytes, nullptr);
           }
         }
       }
       WriteFile(file, ";", 1, &nBytes, nullptr);
     }
   }
   MOZ_SEH_EXCEPT (EXCEPTION_EXECUTE_HANDLER) { }
 }
 static
 wchar_t* getFullPath (PWCHAR filePath, wchar_t* fname)
 {
   // In Windows 8, the first parameter seems to be used for more than just the
   // path name.  For example, its numerical value can be 1.  Passing a non-valid
   // pointer to SearchPathW will cause a crash, so we need to check to see if we
   // are handed a valid pointer, and otherwise just pass nullptr to SearchPathW.
   PWCHAR sanitizedFilePath = (intptr_t(filePath) < 1024) ? nullptr : filePath;
   // figure out the length of the string that we need
   DWORD pathlen = SearchPathW(sanitizedFilePath, fname, L".dll", 0, nullptr,
                               nullptr);
   if (pathlen == 0) {
     return nullptr;
   }
   wchar_t* full_fname = new wchar_t[pathlen+1];
   if (!full_fname) {
     // couldn't allocate memory?
     return nullptr;
   }
   // now actually grab it
   SearchPathW(sanitizedFilePath, fname, L".dll", pathlen + 1, full_fname,
               nullptr);
   return full_fname;
 }
 // No builtin function to find the last character matching a set
 static wchar_t* lastslash(wchar_t* s, int len)
 {
   for (wchar_t* c = s + len - 1; c >= s; --c) {
     if (*c == L'\\' || *c == L'/') {
       return c;
     }
   }
   return nullptr;
 }
 static NTSTATUS NTAPI
 patched_LdrLoadDll (PWCHAR filePath, PULONG flags, PUNICODE_STRING moduleFileName, PHANDLE handle)
 {
   // We have UCS2 (UTF16?), we want ASCII, but we also just want the filename portion
 #define DLLNAME_MAX 128
   char dllName[DLLNAME_MAX+1];
   wchar_t *dll_part;
   char *dot;
   DllBlockInfo *info;
   int len = moduleFileName->Length / 2;
   wchar_t *fname = moduleFileName->Buffer;
   nsAutoArrayPtr<wchar_t> full_fname;
   // The filename isn't guaranteed to be null terminated, but in practice
   // it always will be; ensure that this is so, and bail if not.
   // This is done instead of the more robust approach because of bug 527122,
   // where lots of weird things were happening when we tried to make a copy.
   if (moduleFileName->MaximumLength < moduleFileName->Length+2 ||
       fname[len] != 0)
   {
 #ifdef DEBUG
     printf_stderr("LdrLoadDll: non-null terminated string found!\n");
 #endif
     goto continue_loading;
   }
   dll_part = lastslash(fname, len);
   if (dll_part) {
     dll_part = dll_part + 1;
     len -= dll_part - fname;
   } else {
     dll_part = fname;
   }
 #ifdef DEBUG_very_verbose
   printf_stderr("LdrLoadDll: dll_part '%S' %d\n", dll_part, len);
 #endif
   // if it's too long, then, we assume we won't want to block it,
   // since DLLNAME_MAX should be at least long enough to hold the longest
   // entry in our blocklist.
   if (len > DLLNAME_MAX) {
 #ifdef DEBUG
     printf_stderr("LdrLoadDll: len too long! %d\n", len);
 #endif
     goto continue_loading;
   }
   // copy over to our char byte buffer, lowercasing ASCII as we go
   for (int i = 0; i < len; i++) {
     wchar_t c = dll_part[i];
     if (c > 0x7f) {
       // welp, it's not ascii; if we need to add non-ascii things to
       // our blocklist, we'll have to remove this limitation.
       goto continue_loading;
     }
     // ensure that dll name is all lowercase
     if (c >= 'A' && c <= 'Z')
       c += 'a' - 'A';
     dllName[i] = (char) c;
   }
   dllName[len] = 0;
 #ifdef DEBUG_very_verbose
   printf_stderr("LdrLoadDll: dll name '%s'\n", dllName);
 #endif
   // Block a suspicious binary that uses various 12-digit hex strings
   // e.g. MovieMode.48CA2AEFA22D.dll (bug 973138)
   dot = strchr(dllName, '.');
   if (dot && (strchr(dot+1, '.') == dot+13)) {
     char * end = nullptr;
     _strtoui64(dot+1, &end, 16);
     if (end == dot+13) {
       return STATUS_DLL_NOT_FOUND;
     }
   }
   // then compare to everything on the blocklist
   info = &sWindowsDllBlocklist[0];
   while (info->name) {
     if (strcmp(info->name, dllName) == 0)
       break;
     info++;
   }
   if (info->name) {
     bool load_ok = false;
 #ifdef DEBUG_very_verbose
     printf_stderr("LdrLoadDll: info->name: '%s'\n", info->name);
 #endif
     if ((info->flags == DllBlockInfo::BLOCK_WIN8PLUS_ONLY) &&
         !IsWin8OrLater()) {
       goto continue_loading;
     }
     if ((info->flags == DllBlockInfo::BLOCK_XP_ONLY) &&
         IsWin2003OrLater()) {
       goto continue_loading;
     }
     unsigned long long fVersion = ALL_VERSIONS;
     if (info->maxVersion != ALL_VERSIONS) {
       ReentrancySentinel sentinel(dllName);
       if (sentinel.BailOut()) {
         goto continue_loading;
       }
       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 (info->flags & DllBlockInfo::USE_TIMESTAMP) {
         fVersion = GetTimestamp(full_fname);
         if (fVersion > info->maxVersion) {
           load_ok = true;
         }
       } else {
         DWORD zero;
         DWORD infoSize = GetFileVersionInfoSizeW(full_fname, &zero);
         // If we failed to get the version information, we block.
         if (infoSize != 0) {
           nsAutoArrayPtr<unsigned char> infoData(new unsigned char[infoSize]);
           VS_FIXEDFILEINFO *vInfo;
           UINT vInfoLen;
           if (GetFileVersionInfoW(full_fname, 0, infoSize, infoData) &&
               VerQueryValueW(infoData, L"\\", (LPVOID*) &vInfo, &vInfoLen))
           {
             fVersion =
               ((unsigned long long)vInfo->dwFileVersionMS) << 32 |
               ((unsigned long long)vInfo->dwFileVersionLS);
             // finally do the version check, and if it's greater than our block
             // version, keep loading
             if (fVersion > info->maxVersion)
               load_ok = true;
           }
         }
       }
     }
     if (!load_ok) {
       printf_stderr("LdrLoadDll: Blocking load of '%s' -- see http://www.mozilla.com/en-US/blocklist/\n", dllName);
       DllBlockSet::Add(info->name, fVersion);
       return STATUS_DLL_NOT_FOUND;
     }
   }
 continue_loading:
 #ifdef DEBUG_very_verbose
   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 (IsVistaOrLater() && !CheckASLR(full_fname)) {
       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);
 }
 WindowsDllInterceptor NtDllIntercept;
 } // anonymous namespace
 NS_EXPORT void
 DllBlocklist_Initialize()
 {
   if (GetModuleHandleA("user32.dll")) {
     sUser32BeforeBlocklist = true;
   }
   NtDllIntercept.Init("ntdll.dll");
   ReentrancySentinel::InitializeStatics();
   // We specifically use a detour, because there are cases where external
   // code also tries to hook LdrLoadDll, and doesn't know how to relocate our
   // nop space patches. (Bug 951827)
   bool ok = NtDllIntercept.AddDetour("LdrLoadDll", reinterpret_cast<intptr_t>(patched_LdrLoadDll), (void**) &stub_LdrLoadDll);
   if (!ok) {
     sBlocklistInitFailed = true;
 #ifdef DEBUG
     printf_stderr ("LdrLoadDll hook failed, no dll blocklisting active\n");
 #endif
   }
 }
 NS_EXPORT void
 DllBlocklist_SetInXPCOMLoadOnMainThread(bool inXPCOMLoadOnMainThread)
 {
   if (inXPCOMLoadOnMainThread) {
     MOZ_ASSERT(sThreadLoadingXPCOMModule == 0, "Only one thread should be doing this");
     sThreadLoadingXPCOMModule = GetCurrentThreadId();
   } else {
     sThreadLoadingXPCOMModule = 0;
   }
 }
 NS_EXPORT void
 DllBlocklist_WriteNotes(HANDLE file)
 {
   DWORD nBytes;
   WriteFile(file, kBlockedDllsParameter, kBlockedDllsParameterLen, &nBytes, nullptr);
   DllBlockSet::Write(file);
   WriteFile(file, "\n", 1, &nBytes, nullptr);
   if (sBlocklistInitFailed) {
     WriteFile(file, kBlocklistInitFailedParameter,
               kBlocklistInitFailedParameterLen, &nBytes, nullptr);
   }
   if (sUser32BeforeBlocklist) {
     WriteFile(file, kUser32BeforeBlocklistParameter,
               kUser32BeforeBlocklistParameterLen, &nBytes, nullptr);
   }
 }

The Tor Browser / annotate

mozglue/build/WindowsDllBlocklist.cpp@97036ab72558 (annotated)

mozglue/build/WindowsDllBlocklist.cpp