зеркало из https://github.com/mozilla/gecko-dev.git
336 строки
11 KiB
C++
336 строки
11 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "Compatibility.h"
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#include "mozilla/Telemetry.h"
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#include "mozilla/UniquePtrExtensions.h"
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#include "mozilla/WindowsVersion.h"
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#include "nsDataHashtable.h"
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#include "nsPrintfCString.h"
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#include "nsReadableUtils.h"
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#include "nsString.h"
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#include "nsTHashtable.h"
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#include "nsUnicharUtils.h"
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#include "nsWinUtils.h"
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#include "NtUndoc.h"
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#if defined(UIA_LOGGING)
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# define LOG_ERROR(FuncName) \
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{ \
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DWORD err = ::GetLastError(); \
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nsPrintfCString msg(#FuncName " failed with code %u\n", err); \
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::OutputDebugStringA(msg.get()); \
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}
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#else
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# define LOG_ERROR(FuncName)
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#endif // defined(UIA_LOGGING)
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struct ByteArrayDeleter {
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void operator()(void* aBuf) { delete[] reinterpret_cast<char*>(aBuf); }
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};
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typedef UniquePtr<OBJECT_DIRECTORY_INFORMATION, ByteArrayDeleter> ObjDirInfoPtr;
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// ComparatorFnT returns true to continue searching, or else false to indicate
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// search completion.
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template <typename ComparatorFnT>
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static bool FindNamedObject(const ComparatorFnT& aComparator) {
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// We want to enumerate every named kernel object in our session. We do this
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// by opening a directory object using a path constructed using the session
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// id under which our process resides.
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DWORD sessionId;
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if (!::ProcessIdToSessionId(::GetCurrentProcessId(), &sessionId)) {
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return false;
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}
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nsAutoString path;
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path.AppendPrintf("\\Sessions\\%u\\BaseNamedObjects", sessionId);
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UNICODE_STRING baseNamedObjectsName;
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::RtlInitUnicodeString(&baseNamedObjectsName, path.get());
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OBJECT_ATTRIBUTES attributes;
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InitializeObjectAttributes(&attributes, &baseNamedObjectsName, 0, nullptr,
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nullptr);
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HANDLE rawBaseNamedObjects;
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NTSTATUS ntStatus = ::NtOpenDirectoryObject(
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&rawBaseNamedObjects, DIRECTORY_QUERY | DIRECTORY_TRAVERSE, &attributes);
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if (!NT_SUCCESS(ntStatus)) {
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return false;
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}
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nsAutoHandle baseNamedObjects(rawBaseNamedObjects);
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ULONG context = 0, returnedLen;
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ULONG objDirInfoBufLen = 1024 * sizeof(OBJECT_DIRECTORY_INFORMATION);
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ObjDirInfoPtr objDirInfo(reinterpret_cast<OBJECT_DIRECTORY_INFORMATION*>(
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new char[objDirInfoBufLen]));
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// Now query that directory object for every named object that it contains.
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BOOL firstCall = TRUE;
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do {
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ntStatus = ::NtQueryDirectoryObject(baseNamedObjects, objDirInfo.get(),
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objDirInfoBufLen, FALSE, firstCall,
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&context, &returnedLen);
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#if defined(HAVE_64BIT_BUILD)
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if (!NT_SUCCESS(ntStatus)) {
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return false;
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}
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#else
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if (ntStatus == STATUS_BUFFER_TOO_SMALL) {
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// This case only occurs on 32-bit builds running atop WOW64.
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// (See https://bugzilla.mozilla.org/show_bug.cgi?id=1423999#c3)
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objDirInfo.reset(reinterpret_cast<OBJECT_DIRECTORY_INFORMATION*>(
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new char[returnedLen]));
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objDirInfoBufLen = returnedLen;
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continue;
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} else if (!NT_SUCCESS(ntStatus)) {
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return false;
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}
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#endif
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// NtQueryDirectoryObject gave us an array of OBJECT_DIRECTORY_INFORMATION
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// structures whose final entry is zeroed out.
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OBJECT_DIRECTORY_INFORMATION* curDir = objDirInfo.get();
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while (curDir->mName.Length && curDir->mTypeName.Length) {
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// We use nsDependentSubstring here because UNICODE_STRINGs are not
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// guaranteed to be null-terminated.
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nsDependentSubstring objName(curDir->mName.Buffer,
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curDir->mName.Length / sizeof(wchar_t));
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nsDependentSubstring typeName(curDir->mTypeName.Buffer,
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curDir->mTypeName.Length / sizeof(wchar_t));
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if (!aComparator(objName, typeName)) {
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return true;
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}
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++curDir;
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}
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firstCall = FALSE;
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} while (ntStatus == STATUS_MORE_ENTRIES);
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return false;
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}
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static const char* gBlockedUiaClients[] = {"osk.exe"};
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static bool ShouldBlockUIAClient(nsIFile* aClientExe) {
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if (PR_GetEnv("MOZ_DISABLE_ACCESSIBLE_BLOCKLIST")) {
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return false;
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}
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nsAutoString leafName;
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nsresult rv = aClientExe->GetLeafName(leafName);
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if (NS_FAILED(rv)) {
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return false;
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}
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for (size_t index = 0, len = ArrayLength(gBlockedUiaClients); index < len;
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++index) {
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if (leafName.EqualsIgnoreCase(gBlockedUiaClients[index])) {
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return true;
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}
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}
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return false;
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}
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namespace mozilla {
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namespace a11y {
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Maybe<DWORD> Compatibility::sUiaRemotePid;
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Maybe<bool> Compatibility::OnUIAMessage(WPARAM aWParam, LPARAM aLParam) {
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auto clearUiaRemotePid = MakeScopeExit([]() { sUiaRemotePid = Nothing(); });
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Telemetry::AutoTimer<Telemetry::A11Y_UIA_DETECTION_TIMING_MS> timer;
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// UIA creates a section containing the substring "HOOK_SHMEM_"
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constexpr auto kStrHookShmem = u"HOOK_SHMEM_"_ns;
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// The section name always ends with this suffix, which is derived from the
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// current thread id and the UIA message's WPARAM and LPARAM.
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nsAutoString partialSectionSuffix;
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partialSectionSuffix.AppendPrintf("_%08x_%08x_%08x", ::GetCurrentThreadId(),
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static_cast<DWORD>(aLParam), aWParam);
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// Find any named Section that matches the naming convention of the UIA shared
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// memory.
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nsAutoHandle section;
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auto comparator = [&](const nsDependentSubstring& aName,
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const nsDependentSubstring& aType) -> bool {
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if (aType.Equals(u"Section"_ns) && FindInReadable(kStrHookShmem, aName) &&
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StringEndsWith(aName, partialSectionSuffix)) {
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section.own(::OpenFileMapping(GENERIC_READ, FALSE,
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PromiseFlatString(aName).get()));
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return false;
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}
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return true;
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};
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if (!FindNamedObject(comparator) || !section) {
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return Nothing();
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}
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NTSTATUS ntStatus;
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// First we must query for a list of all the open handles in the system.
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UniquePtr<char[]> handleInfoBuf;
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ULONG handleInfoBufLen = sizeof(SYSTEM_HANDLE_INFORMATION_EX) +
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1024 * sizeof(SYSTEM_HANDLE_TABLE_ENTRY_INFO_EX);
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// We must query for handle information in a loop, since we are effectively
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// asking the kernel to take a snapshot of all the handles on the system;
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// the size of the required buffer may fluctuate between successive calls.
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while (true) {
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// These allocations can be hundreds of megabytes on some computers, so
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// we should use fallible new here.
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handleInfoBuf = MakeUniqueFallible<char[]>(handleInfoBufLen);
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if (!handleInfoBuf) {
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return Nothing();
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}
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ntStatus = ::NtQuerySystemInformation(
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(SYSTEM_INFORMATION_CLASS)SystemExtendedHandleInformation,
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handleInfoBuf.get(), handleInfoBufLen, &handleInfoBufLen);
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if (ntStatus == STATUS_INFO_LENGTH_MISMATCH) {
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continue;
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}
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if (!NT_SUCCESS(ntStatus)) {
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return Nothing();
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}
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break;
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}
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const DWORD ourPid = ::GetCurrentProcessId();
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Maybe<PVOID> kernelObject;
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static Maybe<USHORT> sectionObjTypeIndex;
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nsTHashtable<nsUint32HashKey> nonSectionObjTypes;
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nsDataHashtable<nsVoidPtrHashKey, DWORD> objMap;
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auto handleInfo =
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reinterpret_cast<SYSTEM_HANDLE_INFORMATION_EX*>(handleInfoBuf.get());
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for (ULONG index = 0; index < handleInfo->mHandleCount; ++index) {
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SYSTEM_HANDLE_TABLE_ENTRY_INFO_EX& curHandle = handleInfo->mHandles[index];
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HANDLE handle = reinterpret_cast<HANDLE>(curHandle.mHandle);
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// The mapping of the curHandle.mObjectTypeIndex field depends on the
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// underlying OS kernel. As we scan through the handle list, we record the
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// type indices such that we may use those values to skip over handles that
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// refer to non-section objects.
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if (sectionObjTypeIndex) {
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// If we know the type index for Sections, that's the fastest check...
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if (sectionObjTypeIndex.value() != curHandle.mObjectTypeIndex) {
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// Not a section
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continue;
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}
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} else if (nonSectionObjTypes.Contains(
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static_cast<uint32_t>(curHandle.mObjectTypeIndex))) {
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// Otherwise we check whether or not the object type is definitely _not_
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// a Section...
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continue;
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} else if (ourPid == curHandle.mPid) {
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// Otherwise we need to issue some system calls to find out the object
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// type corresponding to the current handle's type index.
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ULONG objTypeBufLen;
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ntStatus = ::NtQueryObject(handle, ObjectTypeInformation, nullptr, 0,
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&objTypeBufLen);
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if (ntStatus != STATUS_INFO_LENGTH_MISMATCH) {
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continue;
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}
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auto objTypeBuf = MakeUnique<char[]>(objTypeBufLen);
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ntStatus =
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::NtQueryObject(handle, ObjectTypeInformation, objTypeBuf.get(),
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objTypeBufLen, &objTypeBufLen);
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if (!NT_SUCCESS(ntStatus)) {
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continue;
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}
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auto objType =
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reinterpret_cast<PUBLIC_OBJECT_TYPE_INFORMATION*>(objTypeBuf.get());
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// Now we check whether the object's type name matches "Section"
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nsDependentSubstring objTypeName(
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objType->TypeName.Buffer, objType->TypeName.Length / sizeof(wchar_t));
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if (!objTypeName.Equals(u"Section"_ns)) {
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nonSectionObjTypes.PutEntry(
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static_cast<uint32_t>(curHandle.mObjectTypeIndex));
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continue;
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}
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sectionObjTypeIndex = Some(curHandle.mObjectTypeIndex);
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}
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// At this point we know that curHandle references a Section object.
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// Now we can do some actual tests on it.
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if (ourPid != curHandle.mPid) {
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if (kernelObject && kernelObject.value() == curHandle.mObject) {
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// The kernel objects match -- we have found the remote pid!
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sUiaRemotePid = Some(curHandle.mPid);
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break;
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}
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// An object that is not ours. Since we do not yet know which kernel
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// object we're interested in, we'll save the current object for later.
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objMap.Put(curHandle.mObject, curHandle.mPid);
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} else if (handle == section.get()) {
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// This is the file mapping that we opened above. We save this mObject
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// in order to compare to Section objects opened by other processes.
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kernelObject = Some(curHandle.mObject);
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}
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}
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if (!kernelObject) {
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return Nothing();
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}
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if (!sUiaRemotePid) {
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// We found kernelObject *after* we saw the remote process's copy. Now we
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// must look it up in objMap.
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DWORD pid;
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if (objMap.Get(kernelObject.value(), &pid)) {
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sUiaRemotePid = Some(pid);
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}
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}
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if (!sUiaRemotePid) {
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return Nothing();
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}
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a11y::SetInstantiator(sUiaRemotePid.value());
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// Block if necessary
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nsCOMPtr<nsIFile> instantiator;
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if (a11y::GetInstantiator(getter_AddRefs(instantiator)) &&
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ShouldBlockUIAClient(instantiator)) {
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return Some(false);
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}
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return Some(true);
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}
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} // namespace a11y
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} // namespace mozilla
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