gecko-dev/toolkit/xre/nsWindowsDllBlocklist.cpp

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C++

/* -*- 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 <stdio.h>
#include <string.h>
#include <map>
#include "nsXULAppAPI.h"
#include "nsAutoPtr.h"
#include "nsThreadUtils.h"
#include "prlog.h"
#include "nsWindowsDllInterceptor.h"
using namespace mozilla;
#if defined(MOZ_CRASHREPORTER) && !defined(NO_BLOCKLIST_CRASHREPORTER)
#include "nsExceptionHandler.h"
#endif
#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.
unsigned long long maxVersion;
};
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)},
// leave these two in always for tests
{ "mozdllblockingtest.dll", ALL_VERSIONS },
{ "mozdllblockingtest_versioned.dll", 0x0000000400000000ULL },
{ NULL, 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
extern bool gInXPCOMLoadOnMainThread;
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;
NS_ASSERTION(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)) :
nsnull;
}
~RVAMap() {
if (mRealView) {
::UnmapViewOfFile(mRealView);
}
}
operator const T*() const { return mMappedView; }
const T* operator->() const { return mMappedView; }
private:
const T* mMappedView;
void* mRealView;
};
bool
IsVistaOrLater()
{
OSVERSIONINFO info;
ZeroMemory(&info, sizeof(OSVERSIONINFO));
info.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
GetVersionEx(&info);
return info.dwMajorVersion >= 6;
}
bool
CheckASLR(const wchar_t* path)
{
bool retval = false;
HANDLE file = ::CreateFileW(path, GENERIC_READ, FILE_SHARE_READ,
NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL,
NULL);
if (file != INVALID_HANDLE_VALUE) {
HANDLE map = ::CreateFileMappingW(file, NULL, PAGE_READONLY, 0, 0, NULL);
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;
}
/**
* 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();
EnterCriticalSection(&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;
LeaveCriticalSection(&sLock);
}
~ReentrancySentinel()
{
DWORD currentThreadId = GetCurrentThreadId();
EnterCriticalSection(&sLock);
(*sThreadMap)[currentThreadId] = mPreviousDllName;
LeaveCriticalSection(&sLock);
}
bool BailOut() const
{
return mReentered;
};
static void InitializeStatics()
{
InitializeCriticalSection(&sLock);
sThreadMap = new std::map<DWORD, const char*>;
}
private:
static CRITICAL_SECTION sLock;
static std::map<DWORD, const char*>* sThreadMap;
const char* mPreviousDllName;
bool mReentered;
};
CRITICAL_SECTION ReentrancySentinel::sLock;
std::map<DWORD, const char*>* ReentrancySentinel::sThreadMap;
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 NULL to SearchPathW.
PWCHAR sanitizedFilePath = (intptr_t(filePath) < 1024) ? NULL : filePath;
// figure out the length of the string that we need
DWORD pathlen = SearchPathW(sanitizedFilePath, fname, L".dll", 0, NULL, NULL);
if (pathlen == 0) {
return nsnull;
}
wchar_t* full_fname = new wchar_t[pathlen+1];
if (!full_fname) {
// couldn't allocate memory?
return nsnull;
}
// now actually grab it
SearchPathW(sanitizedFilePath, fname, L".dll", pathlen+1, full_fname, NULL);
return full_fname;
}
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;
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 = wcsrchr(fname, L'\\');
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
// 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->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;
}
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))
{
unsigned long long 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);
return STATUS_DLL_NOT_FOUND;
}
}
continue_loading:
#ifdef DEBUG_very_verbose
printf_stderr("LdrLoadDll: continuing load... ('%S')\n", moduleFileName->Buffer);
#endif
NS_SetHasLoadedNewDLLs();
if (gInXPCOMLoadOnMainThread && NS_IsMainThread()) {
// 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
void
XRE_SetupDllBlocklist()
{
NtDllIntercept.Init("ntdll.dll");
ReentrancySentinel::InitializeStatics();
bool ok = NtDllIntercept.AddHook("LdrLoadDll", reinterpret_cast<intptr_t>(patched_LdrLoadDll), (void**) &stub_LdrLoadDll);
#ifdef DEBUG
if (!ok)
printf_stderr ("LdrLoadDll hook failed, no dll blocklisting active\n");
#endif
#if defined(MOZ_CRASHREPORTER) && !defined(NO_BLOCKLIST_CRASHREPORTER)
if (!ok) {
CrashReporter::AppendAppNotesToCrashReport(NS_LITERAL_CSTRING("DllBlockList Failed\n"));
}
#endif
}