diff options
Diffstat (limited to 'toolkit/xre/dllservices/mozglue/interceptor/PatcherNopSpace.h')
| -rw-r--r-- | toolkit/xre/dllservices/mozglue/interceptor/PatcherNopSpace.h | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/toolkit/xre/dllservices/mozglue/interceptor/PatcherNopSpace.h b/toolkit/xre/dllservices/mozglue/interceptor/PatcherNopSpace.h new file mode 100644 index 0000000000..deee87e0f8 --- /dev/null +++ b/toolkit/xre/dllservices/mozglue/interceptor/PatcherNopSpace.h @@ -0,0 +1,205 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* 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 https://mozilla.org/MPL/2.0/. */ + +#ifndef mozilla_interceptor_PatcherNopSpace_h +#define mozilla_interceptor_PatcherNopSpace_h + +#if defined(_M_IX86) + +# include "mozilla/interceptor/PatcherBase.h" + +namespace mozilla { +namespace interceptor { + +template <typename VMPolicy> +class WindowsDllNopSpacePatcher final : public WindowsDllPatcherBase<VMPolicy> { + typedef typename VMPolicy::MMPolicyT MMPolicyT; + + // For remembering the addresses of functions we've patched. + mozilla::Vector<void*> mPatchedFns; + + public: + template <typename... Args> + explicit WindowsDllNopSpacePatcher(Args&&... aArgs) + : WindowsDllPatcherBase<VMPolicy>(std::forward<Args>(aArgs)...) {} + + ~WindowsDllNopSpacePatcher() { Clear(); } + + WindowsDllNopSpacePatcher(const WindowsDllNopSpacePatcher&) = delete; + WindowsDllNopSpacePatcher(WindowsDllNopSpacePatcher&&) = delete; + WindowsDllNopSpacePatcher& operator=(const WindowsDllNopSpacePatcher&) = + delete; + WindowsDllNopSpacePatcher& operator=(WindowsDllNopSpacePatcher&&) = delete; + + void Clear() { + // Restore the mov edi, edi to the beginning of each function we patched. + + for (auto&& ptr : mPatchedFns) { + WritableTargetFunction<MMPolicyT> fn( + this->mVMPolicy, reinterpret_cast<uintptr_t>(ptr), sizeof(uint16_t)); + if (!fn) { + continue; + } + + // mov edi, edi + fn.CommitAndWriteShort(0xff8b); + } + + mPatchedFns.clear(); + } + + /** + * NVIDIA Optimus drivers utilize Microsoft Detours 2.x to patch functions + * in our address space. There is a bug in Detours 2.x that causes it to + * patch at the wrong address when attempting to detour code that is already + * NOP space patched. This function is an effort to detect the presence of + * this NVIDIA code in our address space and disable NOP space patching if it + * is. We also check AppInit_DLLs since this is the mechanism that the Optimus + * drivers use to inject into our process. + */ + static bool IsCompatible() { + // These DLLs are known to have bad interactions with this style of patching + const wchar_t* kIncompatibleDLLs[] = {L"detoured.dll", L"_etoured.dll", + L"nvd3d9wrap.dll", L"nvdxgiwrap.dll"}; + // See if the infringing DLLs are already loaded + for (unsigned int i = 0; i < mozilla::ArrayLength(kIncompatibleDLLs); ++i) { + if (GetModuleHandleW(kIncompatibleDLLs[i])) { + return false; + } + } + if (GetModuleHandleW(L"user32.dll")) { + // user32 is loaded but the infringing DLLs are not, assume we're safe to + // proceed. + return true; + } + // If user32 has not loaded yet, check AppInit_DLLs to ensure that Optimus + // won't be loaded once user32 is initialized. + HKEY hkey = NULL; + if (!RegOpenKeyExW( + HKEY_LOCAL_MACHINE, + L"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Windows", 0, + KEY_QUERY_VALUE, &hkey)) { + nsAutoRegKey key(hkey); + DWORD numBytes = 0; + const wchar_t kAppInitDLLs[] = L"AppInit_DLLs"; + // Query for required buffer size + LONG status = RegQueryValueExW(hkey, kAppInitDLLs, nullptr, nullptr, + nullptr, &numBytes); + mozilla::UniquePtr<wchar_t[]> data; + if (!status) { + // Allocate the buffer and query for the actual data + data = mozilla::MakeUnique<wchar_t[]>((numBytes + 1) / sizeof(wchar_t)); + status = RegQueryValueExW(hkey, kAppInitDLLs, nullptr, nullptr, + (LPBYTE)data.get(), &numBytes); + } + if (!status) { + // For each token, split up the filename components and then check the + // name of the file. + const wchar_t kDelimiters[] = L", "; + wchar_t* tokenContext = nullptr; + wchar_t* token = wcstok_s(data.get(), kDelimiters, &tokenContext); + while (token) { + wchar_t fname[_MAX_FNAME] = {0}; + if (!_wsplitpath_s(token, nullptr, 0, nullptr, 0, fname, + mozilla::ArrayLength(fname), nullptr, 0)) { + // nvinit.dll is responsible for bootstrapping the DLL injection, so + // that is the library that we check for here + const wchar_t kNvInitName[] = L"nvinit"; + if (!_wcsnicmp(fname, kNvInitName, + mozilla::ArrayLength(kNvInitName))) { + return false; + } + } + token = wcstok_s(nullptr, kDelimiters, &tokenContext); + } + } + } + return true; + } + + bool AddHook(FARPROC aTargetFn, intptr_t aHookDest, void** aOrigFunc) { + if (!IsCompatible()) { +# if defined(MOZILLA_INTERNAL_API) + NS_WARNING("NOP space patching is unavailable for compatibility reasons"); +# endif + return false; + } + + MOZ_ASSERT(aTargetFn); + if (!aTargetFn) { + return false; + } + + ReadOnlyTargetFunction<MMPolicyT> readOnlyTargetFn( + this->ResolveRedirectedAddress(aTargetFn)); + + if (!WriteHook(readOnlyTargetFn, aHookDest, aOrigFunc)) { + return false; + } + + return mPatchedFns.append( + reinterpret_cast<void*>(readOnlyTargetFn.GetBaseAddress())); + } + + bool WriteHook(const ReadOnlyTargetFunction<MMPolicyT>& aFn, + intptr_t aHookDest, void** aOrigFunc) { + // Ensure we can read and write starting at fn - 5 (for the long jmp we're + // going to write) and ending at fn + 2 (for the short jmp up to the long + // jmp). These bytes may span two pages with different protection. + WritableTargetFunction<MMPolicyT> writableFn(aFn.Promote(7, -5)); + if (!writableFn) { + return false; + } + + // Check that the 5 bytes before the function are NOP's or INT 3's, + const uint8_t nopOrBp[] = {0x90, 0xCC}; + if (!writableFn.template VerifyValuesAreOneOf<uint8_t, 5>(nopOrBp)) { + return false; + } + + // ... and that the first 2 bytes of the function are mov(edi, edi). + // There are two ways to encode the same thing: + // + // 0x89 0xff == mov r/m, r + // 0x8b 0xff == mov r, r/m + // + // where "r" is register and "r/m" is register or memory. + // Windows seems to use 0x8B 0xFF. We include 0x89 0xFF out of paranoia. + + // (These look backwards because little-endian) + const uint16_t possibleEncodings[] = {0xFF8B, 0xFF89}; + if (!writableFn.template VerifyValuesAreOneOf<uint16_t, 1>( + possibleEncodings, 5)) { + return false; + } + + // Write a long jump into the space above the function. + writableFn.WriteByte(0xe9); // jmp + if (!writableFn) { + return false; + } + + writableFn.WriteDisp32(aHookDest); // target + if (!writableFn) { + return false; + } + + // Set aOrigFunc here, because after this point, aHookDest might be called, + // and aHookDest might use the aOrigFunc pointer. + *aOrigFunc = reinterpret_cast<void*>(writableFn.GetCurrentAddress() + + sizeof(uint16_t)); + + // Short jump up into our long jump. + return writableFn.CommitAndWriteShort(0xF9EB); // jmp $-5 + } +}; + +} // namespace interceptor +} // namespace mozilla + +#endif // defined(_M_IX86) + +#endif // mozilla_interceptor_PatcherNopSpace_h |