1 files changed, 253 insertions, 0 deletions
diff --git a/toolkit/xre/dllservices/ModuleEvaluator.cpp b/toolkit/xre/dllservices/ModuleEvaluator.cpp
new file mode 100644
index 0000000000..58814e34a5
--- /dev/null
+++ b/toolkit/xre/dllservices/ModuleEvaluator.cpp
@@ -0,0 +1,253 @@
+/* -*- 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/. */
+
+#include "ModuleEvaluator.h"
+
+#include <algorithm>  // For std::find()
+#include <type_traits>
+
+#include <windows.h>
+#include <shlobj.h>
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/ModuleVersionInfo.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Unused.h"
+#include "mozilla/WinDllServices.h"
+#include "mozilla/WinHeaderOnlyUtils.h"
+#include "nsReadableUtils.h"
+#include "nsWindowsHelpers.h"
+#include "nsXULAppAPI.h"
+
+namespace mozilla {
+
+// Fills a Vector with keyboard layout DLLs found in the registry.
+// These are leaf names only, not full paths. Here we will convert them to
+// lowercase before returning, to facilitate case-insensitive searches.
+// On error, this may return partial results.
+static Vector<nsString> GetKeyboardLayoutDlls() {
+  Vector<nsString> result;
+
+  HKEY rawKey;
+  if (::RegOpenKeyExW(HKEY_LOCAL_MACHINE,
+                      L"SYSTEM\\CurrentControlSet\\Control\\Keyboard Layouts",
+                      0, KEY_ENUMERATE_SUB_KEYS, &rawKey) != ERROR_SUCCESS) {
+    return result;
+  }
+  nsAutoRegKey key(rawKey);
+
+  DWORD iKey = 0;
+  wchar_t strTemp[MAX_PATH] = {};
+  while (true) {
+    DWORD strTempSize = ArrayLength(strTemp);
+    if (RegEnumKeyExW(rawKey, iKey, strTemp, &strTempSize, nullptr, nullptr,
+                      nullptr, nullptr) != ERROR_SUCCESS) {
+      // ERROR_NO_MORE_ITEMS or a real error: bail with what we have.
+      return result;
+    }
+    iKey++;
+
+    strTempSize = sizeof(strTemp);
+    if (::RegGetValueW(rawKey, strTemp, L"Layout File", RRF_RT_REG_SZ, nullptr,
+                       strTemp, &strTempSize) == ERROR_SUCCESS &&
+        strTempSize) {
+      nsString ws(strTemp, ((strTempSize + 1) / sizeof(wchar_t)) - 1);
+      ToLowerCase(ws);  // To facilitate case-insensitive searches
+      Unused << result.emplaceBack(std::move(ws));
+    }
+  }
+
+  return result;
+}
+
+/* static */
+bool ModuleEvaluator::ResolveKnownFolder(REFKNOWNFOLDERID aFolderId,
+                                         nsIFile** aOutFile) {
+  if (!aOutFile) {
+    return false;
+  }
+
+  *aOutFile = nullptr;
+
+  // Since we're running off main thread, we can't use NS_GetSpecialDirectory
+  PWSTR rawPath = nullptr;
+  HRESULT hr =
+      ::SHGetKnownFolderPath(aFolderId, KF_FLAG_DEFAULT, nullptr, &rawPath);
+  if (FAILED(hr)) {
+    return false;
+  }
+
+  using ShellStringUniquePtr =
+      UniquePtr<std::remove_pointer_t<PWSTR>, CoTaskMemFreeDeleter>;
+
+  ShellStringUniquePtr path(rawPath);
+
+  nsresult rv = NS_NewLocalFile(nsDependentString(path.get()), false, aOutFile);
+  return NS_SUCCEEDED(rv);
+}
+
+ModuleEvaluator::ModuleEvaluator()
+    : mKeyboardLayoutDlls(GetKeyboardLayoutDlls()) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+#if defined(_M_IX86)
+  // We want to resolve to SYSWOW64 when applicable
+  REFKNOWNFOLDERID systemFolderId = FOLDERID_SystemX86;
+#else
+  REFKNOWNFOLDERID systemFolderId = FOLDERID_System;
+#endif  // defined(_M_IX86)
+
+  bool resolveOk =
+      ResolveKnownFolder(systemFolderId, getter_AddRefs(mSysDirectory));
+  MOZ_ASSERT(resolveOk);
+  if (!resolveOk) {
+    return;
+  }
+
+  nsCOMPtr<nsIFile> winSxSDir;
+  resolveOk = ResolveKnownFolder(FOLDERID_Windows, getter_AddRefs(winSxSDir));
+  MOZ_ASSERT(resolveOk);
+  if (!resolveOk) {
+    return;
+  }
+
+  nsresult rv = winSxSDir->Append(u"WinSxS"_ns);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  mWinSxSDirectory = std::move(winSxSDir);
+
+  nsCOMPtr<nsIFile> exeFile;
+  rv = XRE_GetBinaryPath(getter_AddRefs(exeFile));
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  rv = exeFile->GetParent(getter_AddRefs(mExeDirectory));
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  nsAutoString exePath;
+  rv = exeFile->GetPath(exePath);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+  if (NS_FAILED(rv)) {
+    return;
+  }
+
+  ModuleVersionInfo exeVi;
+  if (!exeVi.GetFromImage(exePath)) {
+    return;
+  }
+
+  mExeVersion = Some(ModuleVersion(exeVi.mFileVersion.Version64()));
+}
+
+ModuleEvaluator::operator bool() const {
+  return mExeVersion.isSome() && mExeDirectory && mSysDirectory &&
+         mWinSxSDirectory;
+}
+
+Maybe<ModuleTrustFlags> ModuleEvaluator::GetTrust(
+    const ModuleRecord& aModuleRecord) const {
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+  // We start by checking authenticode signatures, as the presence of any
+  // signature will produce an immediate pass/fail.
+  if (aModuleRecord.mVendorInfo.isSome() &&
+      aModuleRecord.mVendorInfo.ref().mSource ==
+          VendorInfo::Source::Signature) {
+    const nsString& signedBy = aModuleRecord.mVendorInfo.ref().mVendor;
+
+    if (signedBy.EqualsLiteral("Microsoft Windows")) {
+      return Some(ModuleTrustFlags::MicrosoftWindowsSignature);
+    } else if (signedBy.EqualsLiteral("Microsoft Corporation")) {
+      return Some(ModuleTrustFlags::MicrosoftWindowsSignature);
+    } else if (signedBy.EqualsLiteral("Mozilla Corporation")) {
+      return Some(ModuleTrustFlags::MozillaSignature);
+    } else {
+      // Being signed by somebody who is neither Microsoft nor us is an
+      // automatic and immediate disqualification.
+      return Some(ModuleTrustFlags::None);
+    }
+  }
+
+  const nsCOMPtr<nsIFile>& dllFile = aModuleRecord.mResolvedDosName;
+  MOZ_ASSERT(!!dllFile);
+  if (!dllFile) {
+    return Nothing();
+  }
+
+  nsAutoString dllLeafLower;
+  if (NS_FAILED(dllFile->GetLeafName(dllLeafLower))) {
+    return Nothing();
+  }
+
+  ToLowerCase(dllLeafLower);  // To facilitate case-insensitive searching
+
+  // The JIT profiling module doesn't really have any other practical way to
+  // match; hard-code it as being trusted.
+  if (dllLeafLower.EqualsLiteral("jitpi.dll")) {
+    return Some(ModuleTrustFlags::JitPI);
+  }
+
+  ModuleTrustFlags result = ModuleTrustFlags::None;
+
+  nsresult rv;
+  bool contained;
+
+  // Is the DLL in the system directory?
+  rv = mSysDirectory->Contains(dllFile, &contained);
+  if (NS_SUCCEEDED(rv) && contained) {
+    result |= ModuleTrustFlags::SystemDirectory;
+  }
+
+  // Is the DLL in the WinSxS directory? Some Microsoft DLLs (e.g. comctl32) are
+  // loaded from here and don't have digital signatures. So while this is not a
+  // guarantee of trustworthiness, but is at least as valid as system32.
+  rv = mWinSxSDirectory->Contains(dllFile, &contained);
+  if (NS_SUCCEEDED(rv) && contained) {
+    result |= ModuleTrustFlags::WinSxSDirectory;
+  }
+
+  // Is it a keyboard layout DLL?
+  if (std::find(mKeyboardLayoutDlls.begin(), mKeyboardLayoutDlls.end(),
+                dllLeafLower) != mKeyboardLayoutDlls.end()) {
+    result |= ModuleTrustFlags::KeyboardLayout;
+    // This doesn't guarantee trustworthiness by itself. Keyboard layouts also
+    // must be in the system directory.
+  }
+
+  if (aModuleRecord.mVendorInfo.isSome() &&
+      aModuleRecord.mVendorInfo.ref().mSource ==
+          VendorInfo::Source::VersionInfo) {
+    const nsString& companyName = aModuleRecord.mVendorInfo.ref().mVendor;
+
+    if (companyName.EqualsLiteral("Microsoft Corporation")) {
+      result |= ModuleTrustFlags::MicrosoftVersion;
+    }
+  }
+
+  rv = mExeDirectory->Contains(dllFile, &contained);
+  if (NS_SUCCEEDED(rv) && contained) {
+    result |= ModuleTrustFlags::FirefoxDirectory;
+
+    // If the DLL is in the Firefox directory, does it also share the Firefox
+    // version info?
+    if (mExeVersion.isSome() && aModuleRecord.mVersion.isSome() &&
+        mExeVersion.value() == aModuleRecord.mVersion.value()) {
+      result |= ModuleTrustFlags::FirefoxDirectoryAndVersion;
+    }
+  }
+
+  return Some(result);
+}
+
+}  // namespace mozilla