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/* -*- 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));
}
}
}
/* 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().mHasNestedMicrosoftSignature) {
return Some(ModuleTrustFlags::MicrosoftWindowsSignature);
}
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
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