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gecko-dev/mozglue/build/WindowsDllBlocklist.cpp

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/* -*- 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/. */
#ifdef MOZ_MEMORY
# define MOZ_MEMORY_IMPL
# include "mozmemory_wrap.h"
# define MALLOC_FUNCS MALLOC_FUNCS_MALLOC
// See mozmemory_wrap.h for more details. This file is part of libmozglue, so
// it needs to use _impl suffixes.
# define MALLOC_DECL(name, return_type, ...) \
MOZ_MEMORY_API return_type name##_impl(__VA_ARGS__);
# include "malloc_decls.h"
# include "mozilla/mozalloc.h"
#endif
#include <windows.h>
#include <winternl.h>
#pragma warning(push)
#pragma warning(disable : 4275 4530) // See msvc-stl-wrapper.template.h
#include <map>
#pragma warning(pop)
#include "Authenticode.h"
#include "CrashAnnotations.h"
#include "MozglueUtils.h"
#include "UntrustedDllsHandler.h"
#include "nsAutoPtr.h"
#include "nsWindowsDllInterceptor.h"
#include "mozilla/CmdLineAndEnvUtils.h"
#include "mozilla/DebugOnly.h"
#include "mozilla/ScopeExit.h"
#include "mozilla/StackWalk_windows.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/Vector.h"
#include "mozilla/WindowsVersion.h"
#include "nsWindowsHelpers.h"
#include "WindowsDllBlocklist.h"
#include "mozilla/AutoProfilerLabel.h"
#include "mozilla/glue/Debug.h"
#include "mozilla/glue/WindowsDllServices.h"
using namespace mozilla;
using CrashReporter::Annotation;
using CrashReporter::AnnotationToString;
static glue::Win32SRWLock gDllServicesLock;
static glue::detail::DllServicesBase* gDllServices;
#define DLL_BLOCKLIST_ENTRY(name, ...) {name, __VA_ARGS__},
#define DLL_BLOCKLIST_STRING_TYPE const char*
#include "mozilla/WindowsDllBlocklistDefs.h"
// define this for very verbose dll load debug spew
#undef DEBUG_very_verbose
static uint32_t sInitFlags;
static bool sBlocklistInitAttempted;
static bool sBlocklistInitFailed;
static bool sUser32BeforeBlocklist;
// This feature is enabled only on NIGHTLY, only for the main process.
inline static bool IsUntrustedDllsHandlerEnabled() {
#ifdef NIGHTLY_BUILD
return !(sInitFlags & eDllBlocklistInitFlagIsChildProcess);
#else
return false;
#endif
}
typedef MOZ_NORETURN_PTR void(__fastcall* BaseThreadInitThunk_func)(
BOOL aIsInitialThread, void* aStartAddress, void* aThreadParam);
static WindowsDllInterceptor::FuncHookType<BaseThreadInitThunk_func>
stub_BaseThreadInitThunk;
typedef NTSTATUS(NTAPI* LdrLoadDll_func)(PWCHAR filePath, PULONG flags,
PUNICODE_STRING moduleFileName,
PHANDLE handle);
static WindowsDllInterceptor::FuncHookType<LdrLoadDll_func> stub_LdrLoadDll;
#ifdef _M_AMD64
typedef decltype(
RtlInstallFunctionTableCallback)* RtlInstallFunctionTableCallback_func;
static WindowsDllInterceptor::FuncHookType<RtlInstallFunctionTableCallback_func>
stub_RtlInstallFunctionTableCallback;
extern uint8_t* sMsMpegJitCodeRegionStart;
extern size_t sMsMpegJitCodeRegionSize;
BOOLEAN WINAPI patched_RtlInstallFunctionTableCallback(
DWORD64 TableIdentifier, DWORD64 BaseAddress, DWORD Length,
PGET_RUNTIME_FUNCTION_CALLBACK Callback, PVOID Context,
PCWSTR OutOfProcessCallbackDll) {
// msmpeg2vdec.dll sets up a function table callback for their JIT code that
// just terminates the process, because their JIT doesn't have unwind info.
// If we see this callback being registered, record the region address, so
// that StackWalk.cpp can avoid unwinding addresses in this region.
//
// To keep things simple I'm not tracking unloads of msmpeg2vdec.dll.
// Worst case the stack walker will needlessly avoid a few pages of memory.
// Tricky: GetModuleHandleExW adds a ref by default; GetModuleHandleW doesn't.
HMODULE callbackModule = nullptr;
DWORD moduleFlags = GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT;
// These GetModuleHandle calls enter a critical section on Win7.
AutoSuppressStackWalking suppress;
if (GetModuleHandleExW(moduleFlags, (LPWSTR)Callback, &callbackModule) &&
GetModuleHandleW(L"msmpeg2vdec.dll") == callbackModule) {
sMsMpegJitCodeRegionStart = (uint8_t*)BaseAddress;
sMsMpegJitCodeRegionSize = Length;
}
return stub_RtlInstallFunctionTableCallback(TableIdentifier, BaseAddress,
Length, Callback, Context,
OutOfProcessCallbackDll);
}
#endif
template <class T>
struct RVAMap {
RVAMap(HANDLE map, DWORD offset) {
SYSTEM_INFO info;
GetSystemInfo(&info);
DWORD alignedOffset =
(offset / info.dwAllocationGranularity) * info.dwAllocationGranularity;
MOZ_ASSERT(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))
: nullptr;
}
~RVAMap() {
if (mRealView) {
::UnmapViewOfFile(mRealView);
}
}
operator const T*() const { return mMappedView; }
const T* operator->() const { return mMappedView; }
private:
const T* mMappedView;
void* mRealView;
};
static DWORD GetTimestamp(const wchar_t* path) {
DWORD timestamp = 0;
HANDLE file = ::CreateFileW(path, GENERIC_READ, FILE_SHARE_READ, nullptr,
OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
if (file != INVALID_HANDLE_VALUE) {
HANDLE map =
::CreateFileMappingW(file, nullptr, PAGE_READONLY, 0, 0, nullptr);
if (map) {
RVAMap<IMAGE_DOS_HEADER> peHeader(map, 0);
if (peHeader) {
RVAMap<IMAGE_NT_HEADERS> ntHeader(map, peHeader->e_lfanew);
if (ntHeader) {
timestamp = ntHeader->FileHeader.TimeDateStamp;
}
}
::CloseHandle(map);
}
::CloseHandle(file);
}
return timestamp;
}
// This lock protects both the reentrancy sentinel and the crash reporter
// data structures.
static CRITICAL_SECTION sLock;
/**
* 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();
AutoCriticalSection lock(&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;
}
~ReentrancySentinel() {
DWORD currentThreadId = GetCurrentThreadId();
AutoCriticalSection lock(&sLock);
(*sThreadMap)[currentThreadId] = mPreviousDllName;
}
bool BailOut() const { return mReentered; };
static void InitializeStatics() {
InitializeCriticalSection(&sLock);
sThreadMap = new std::map<DWORD, const char*>;
}
private:
static std::map<DWORD, const char*>* sThreadMap;
const char* mPreviousDllName;
bool mReentered;
};
std::map<DWORD, const char*>* ReentrancySentinel::sThreadMap;
/**
* This is a linked list of DLLs that have been blocked. It doesn't use
* mozilla::LinkedList because this is an append-only list and doesn't need
* to be doubly linked.
*/
class DllBlockSet {
public:
static void Add(const char* name, unsigned long long version);
// Write the list of blocked DLLs to a file HANDLE. This method is run after
// a crash occurs and must therefore not use the heap, etc.
static void Write(HANDLE file);
private:
DllBlockSet(const char* name, unsigned long long version)
: mName(name), mVersion(version), mNext(nullptr) {}
const char* mName; // points into the gWindowsDllBlocklist string
unsigned long long mVersion;
DllBlockSet* mNext;
static DllBlockSet* gFirst;
};
DllBlockSet* DllBlockSet::gFirst;
void DllBlockSet::Add(const char* name, unsigned long long version) {
AutoCriticalSection lock(&sLock);
for (DllBlockSet* b = gFirst; b; b = b->mNext) {
if (0 == strcmp(b->mName, name) && b->mVersion == version) {
return;
}
}
// Not already present
DllBlockSet* n = new DllBlockSet(name, version);
n->mNext = gFirst;
gFirst = n;
}
void DllBlockSet::Write(HANDLE file) {
// It would be nicer to use AutoCriticalSection here. However, its destructor
// might not run if an exception occurs, in which case we would never leave
// the critical section. (MSVC warns about this possibility.) So we
// enter and leave manually.
::EnterCriticalSection(&sLock);
// Because this method is called after a crash occurs, and uses heap memory,
// protect this entire block with a structured exception handler.
MOZ_SEH_TRY {
DWORD nBytes;
for (DllBlockSet* b = gFirst; b; b = b->mNext) {
// write name[,v.v.v.v];
WriteFile(file, b->mName, strlen(b->mName), &nBytes, nullptr);
if (b->mVersion != ALL_VERSIONS) {
WriteFile(file, ",", 1, &nBytes, nullptr);
uint16_t parts[4];
parts[0] = b->mVersion >> 48;
parts[1] = (b->mVersion >> 32) & 0xFFFF;
parts[2] = (b->mVersion >> 16) & 0xFFFF;
parts[3] = b->mVersion & 0xFFFF;
for (int p = 0; p < 4; ++p) {
char buf[32];
ltoa(parts[p], buf, 10);
WriteFile(file, buf, strlen(buf), &nBytes, nullptr);
if (p != 3) {
WriteFile(file, ".", 1, &nBytes, nullptr);
}
}
}
WriteFile(file, ";", 1, &nBytes, nullptr);
}
}
MOZ_SEH_EXCEPT(EXCEPTION_EXECUTE_HANDLER) {}
::LeaveCriticalSection(&sLock);
}
static UniquePtr<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 nullptr to SearchPathW.
PWCHAR sanitizedFilePath = nullptr;
if ((uintptr_t(filePath) >= 65536) && ((uintptr_t(filePath) & 1) == 0)) {
sanitizedFilePath = filePath;
}
// figure out the length of the string that we need
DWORD pathlen =
SearchPathW(sanitizedFilePath, fname, L".dll", 0, nullptr, nullptr);
if (pathlen == 0) {
return nullptr;
}
auto full_fname = MakeUnique<wchar_t[]>(pathlen + 1);
if (!full_fname) {
// couldn't allocate memory?
return nullptr;
}
// now actually grab it
SearchPathW(sanitizedFilePath, fname, L".dll", pathlen + 1, full_fname.get(),
nullptr);
return full_fname;
}
// No builtin function to find the last character matching a set
static wchar_t* lastslash(wchar_t* s, int len) {
for (wchar_t* c = s + len - 1; c >= s; --c) {
if (*c == L'\\' || *c == L'/') {
return c;
}
}
return nullptr;
}
#ifdef ENABLE_TESTS
DllLoadHookType gDllLoadHook = nullptr;
void DllBlocklist_SetDllLoadHook(DllLoadHookType aHook) {
gDllLoadHook = aHook;
}
void CallDllLoadHook(bool aDllLoaded, NTSTATUS aStatus, HANDLE aDllBase,
PUNICODE_STRING aDllName) {
if (gDllLoadHook) {
gDllLoadHook(aDllLoaded, aStatus, aDllBase, aDllName);
}
}
CreateThreadHookType gCreateThreadHook = nullptr;
void DllBlocklist_SetCreateThreadHook(CreateThreadHookType aHook) {
gCreateThreadHook = aHook;
}
void CallCreateThreadHook(bool aWasAllowed, void* aStartAddress) {
if (gCreateThreadHook) {
gCreateThreadHook(aWasAllowed, aStartAddress);
}
}
// This function does the work for gtest TestDllBlocklist.BlocklistIntegrity.
// If the test fails, the return value is the pointer to a string description
// of the failure. If the test passes, the return value is nullptr.
const char* DllBlocklist_TestBlocklistIntegrity() {
mozilla::Vector<DLL_BLOCKLIST_STRING_TYPE> dupes;
DECLARE_POINTER_TO_FIRST_DLL_BLOCKLIST_ENTRY(pFirst);
DECLARE_POINTER_TO_LAST_DLL_BLOCKLIST_ENTRY(pLast);
if (pLast->name || pLast->maxVersion || pLast->flags) {
return "The last dll blocklist entry must be all-null.";
}
for (size_t i = 0; i < mozilla::ArrayLength(gWindowsDllBlocklist) - 1; ++i) {
auto pEntry = pFirst + i;
// Validate name
if (!pEntry->name) {
return "A dll blocklist entry contains a null name.";
}
if (strlen(pEntry->name) <= 2) {
return "Dll blocklist entry names must be longer than 2 characters.";
}
// Check the filename for valid characters.
for (auto pch = pEntry->name; *pch != 0; ++pch) {
if (*pch >= 'A' && *pch <= 'Z') {
return "Dll blocklist entry names cannot contain uppercase characters.";
}
}
// Check for duplicate entries
for (auto dupe : dupes) {
if (!stricmp(dupe, pEntry->name)) {
return "At least one duplicate dll blocklist entry was found.";
}
}
if (!dupes.append(pEntry->name)) {
return "Failed to append to duplicates list; test unable to continue.";
}
}
return nullptr;
}
#else // ENABLE_TESTS
# define CallDllLoadHook(...)
# define CallCreateThreadHook(...)
#endif // ENABLE_TESTS
static NTSTATUS NTAPI patched_LdrLoadDll(PWCHAR filePath, PULONG flags,
PUNICODE_STRING moduleFileName,
PHANDLE handle) {
if (IsUntrustedDllsHandlerEnabled()) {
glue::UntrustedDllsHandler::EnterLoaderCall();
}
// Warning: this must be at the top function scope.
auto exitLoaderCallScopeExit = MakeScopeExit([]() {
if (IsUntrustedDllsHandlerEnabled()) {
glue::UntrustedDllsHandler::ExitLoaderCall();
}
});
// 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;
char* dot;
int len = moduleFileName->Length / 2;
wchar_t* fname = moduleFileName->Buffer;
UniquePtr<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 = lastslash(fname, len);
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
if (!(sInitFlags & eDllBlocklistInitFlagWasBootstrapped)) {
// Block a suspicious binary that uses various 12-digit hex strings
// e.g. MovieMode.48CA2AEFA22D.dll (bug 973138)
dot = strchr(dllName, '.');
if (dot && (strchr(dot + 1, '.') == dot + 13)) {
char* end = nullptr;
_strtoui64(dot + 1, &end, 16);
if (end == dot + 13) {
CallDllLoadHook(false, STATUS_DLL_NOT_FOUND, 0, moduleFileName);
return STATUS_DLL_NOT_FOUND;
}
}
// Block binaries where the filename is at least 16 hex digits
if (dot && ((dot - dllName) >= 16)) {
char* current = dllName;
while (current < dot && isxdigit(*current)) {
current++;
}
if (current == dot) {
CallDllLoadHook(false, STATUS_DLL_NOT_FOUND, 0, moduleFileName);
return STATUS_DLL_NOT_FOUND;
}
}
// then compare to everything on the blocklist
DECLARE_POINTER_TO_FIRST_DLL_BLOCKLIST_ENTRY(info);
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->flags & DllBlockInfo::BLOCK_WIN8PLUS_ONLY) &&
!IsWin8OrLater()) {
goto continue_loading;
}
if ((info->flags & DllBlockInfo::BLOCK_WIN8_ONLY) &&
(!IsWin8OrLater() || IsWin8Point1OrLater())) {
goto continue_loading;
}
if ((info->flags & DllBlockInfo::CHILD_PROCESSES_ONLY) &&
!(sInitFlags & eDllBlocklistInitFlagIsChildProcess)) {
goto continue_loading;
}
unsigned long long fVersion = ALL_VERSIONS;
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);
CallDllLoadHook(false, STATUS_DLL_NOT_FOUND, 0, moduleFileName);
return STATUS_DLL_NOT_FOUND;
}
if (info->flags & DllBlockInfo::USE_TIMESTAMP) {
fVersion = GetTimestamp(full_fname.get());
if (fVersion > info->maxVersion) {
load_ok = true;
}
} else {
DWORD zero;
DWORD infoSize = GetFileVersionInfoSizeW(full_fname.get(), &zero);
// If we failed to get the version information, we block.
if (infoSize != 0) {
auto infoData = MakeUnique<unsigned char[]>(infoSize);
VS_FIXEDFILEINFO* vInfo;
UINT vInfoLen;
if (GetFileVersionInfoW(full_fname.get(), 0, infoSize,
infoData.get()) &&
VerQueryValueW(infoData.get(), L"\\", (LPVOID*)&vInfo,
&vInfoLen)) {
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);
DllBlockSet::Add(info->name, fVersion);
CallDllLoadHook(false, STATUS_DLL_NOT_FOUND, 0, moduleFileName);
return STATUS_DLL_NOT_FOUND;
}
}
}
continue_loading:
#ifdef DEBUG_very_verbose
printf_stderr("LdrLoadDll: continuing load... ('%S')\n",
moduleFileName->Buffer);
#endif
// A few DLLs such as xul.dll and nss3.dll get loaded before mozglue's
// AutoProfilerLabel is initialized, and this is a no-op in those cases. But
// the vast majority of DLLs do get labelled here.
AutoProfilerLabel label("WindowsDllBlocklist::patched_LdrLoadDll", dllName);
#ifdef _M_AMD64
// Prevent the stack walker from suspending this thread when LdrLoadDll
// holds the RtlLookupFunctionEntry lock.
AutoSuppressStackWalking suppress;
#endif
NTSTATUS ret;
HANDLE myHandle;
if (IsUntrustedDllsHandlerEnabled()) {
TimeStamp loadStart = TimeStamp::Now();
ret = stub_LdrLoadDll(filePath, flags, moduleFileName, &myHandle);
TimeStamp loadEnd = TimeStamp::Now();
if (NT_SUCCESS(ret)) {
double loadDurationMS = (loadEnd - loadStart).ToMilliseconds();
// Win32 HMODULEs use the bottom two bits as flags. Ensure those bits are
// cleared so we're left with the base address value.
glue::UntrustedDllsHandler::OnAfterModuleLoad(
(uintptr_t)myHandle & ~(uintptr_t)3, moduleFileName, loadDurationMS);
glue::AutoSharedLock lock(gDllServicesLock);
if (gDllServices) {
Vector<glue::ModuleLoadEvent, 0, InfallibleAllocPolicy> events;
if (glue::UntrustedDllsHandler::TakePendingEvents(events)) {
gDllServices->NotifyUntrustedModuleLoads(events);
}
}
}
} else {
ret = stub_LdrLoadDll(filePath, flags, moduleFileName, &myHandle);
}
if (handle) {
*handle = myHandle;
}
CallDllLoadHook(NT_SUCCESS(ret), ret, handle ? *handle : 0, moduleFileName);
return ret;
}
#if defined(NIGHTLY_BUILD)
// Map of specific thread proc addresses we should block. In particular,
// LoadLibrary* APIs which indicate DLL injection
static mozilla::Vector<void*, 4>* gStartAddressesToBlock;
#endif
static bool ShouldBlockThread(void* aStartAddress) {
// Allows crashfirefox.exe to continue to work. Also if your threadproc is
// null, this crash is intentional.
if (aStartAddress == 0) return false;
#if defined(NIGHTLY_BUILD)
for (auto p : *gStartAddressesToBlock) {
if (p == aStartAddress) {
return true;
}
}
#endif
bool shouldBlock = false;
MEMORY_BASIC_INFORMATION startAddressInfo = {0};
if (VirtualQuery(aStartAddress, &startAddressInfo,
sizeof(startAddressInfo))) {
shouldBlock |= startAddressInfo.State != MEM_COMMIT;
shouldBlock |= startAddressInfo.Protect != PAGE_EXECUTE_READ;
}
return shouldBlock;
}
// Allows blocked threads to still run normally through BaseThreadInitThunk, in
// case there's any magic there that we shouldn't skip.
static DWORD WINAPI NopThreadProc(void* /* aThreadParam */) { return 0; }
static MOZ_NORETURN void __fastcall patched_BaseThreadInitThunk(
BOOL aIsInitialThread, void* aStartAddress, void* aThreadParam) {
if (ShouldBlockThread(aStartAddress)) {
CallCreateThreadHook(false, aStartAddress);
aStartAddress = (void*)NopThreadProc;
} else {
CallCreateThreadHook(true, aStartAddress);
}
stub_BaseThreadInitThunk(aIsInitialThread, aStartAddress, aThreadParam);
}
static WindowsDllInterceptor NtDllIntercept;
static WindowsDllInterceptor Kernel32Intercept;
static void GetNativeNtBlockSetWriter();
MFBT_API void DllBlocklist_Initialize(uint32_t aInitFlags) {
if (sBlocklistInitAttempted) {
return;
}
sInitFlags = aInitFlags;
if (sInitFlags & eDllBlocklistInitFlagWasBootstrapped) {
GetNativeNtBlockSetWriter();
}
sBlocklistInitAttempted = true;
#if defined(NIGHTLY_BUILD)
gStartAddressesToBlock = new mozilla::Vector<void*, 4>;
#endif
if (IsUntrustedDllsHandlerEnabled()) {
#ifdef ENABLE_TESTS
// Check whether we are running as an xpcshell test.
if (mozilla::EnvHasValue("XPCSHELL_TEST_PROFILE_DIR")) {
// For xpcshell tests, load this untrusted DLL early enough that the
// untrusted module evaluator counts it as a startup module.
// It is located in the current directory; the full path must be specified
// or LoadLibrary() fails during xpcshell tests with ERROR_MOD_NOT_FOUND.
// This buffer will hold current directory + dll name
wchar_t dllFullPath[MAX_PATH] = {};
static const wchar_t kTestDllName[] = L"\\untrusted-startup-test-dll.dll";
// The amount of the buffer available to store the current directory,
// leaving room for the dll name.
static const DWORD kBufferDirLen =
ArrayLength(dllFullPath) - ArrayLength(kTestDllName);
DWORD ret = ::GetCurrentDirectoryW(kBufferDirLen, dllFullPath);
if ((ret > kBufferDirLen) || !ret) {
// Buffer too small or the call failed
printf_stderr("Unable to load %S; GetCurrentDirectoryW failed: %lu",
kTestDllName, GetLastError());
} else {
wcscat_s(dllFullPath, kTestDllName);
HMODULE hTestDll = ::LoadLibraryW(dllFullPath);
if (!hTestDll) {
printf_stderr("Unable to load %S; LoadLibraryW failed: %lu",
kTestDllName, GetLastError());
}
}
}
#endif
glue::UntrustedDllsHandler::Init();
}
// In order to be effective against AppInit DLLs, the blocklist must be
// initialized before user32.dll is loaded into the process (bug 932100).
if (GetModuleHandleA("user32.dll")) {
sUser32BeforeBlocklist = true;
#ifdef DEBUG
printf_stderr("DLL blocklist was unable to intercept AppInit DLLs.\n");
#endif
}
NtDllIntercept.Init("ntdll.dll");
ReentrancySentinel::InitializeStatics();
// We specifically use a detour, because there are cases where external
// code also tries to hook LdrLoadDll, and doesn't know how to relocate our
// nop space patches. (Bug 951827)
bool ok = stub_LdrLoadDll.SetDetour(NtDllIntercept, "LdrLoadDll",
&patched_LdrLoadDll);
if (!ok) {
sBlocklistInitFailed = true;
#ifdef DEBUG
printf_stderr("LdrLoadDll hook failed, no dll blocklisting active\n");
#endif
}
// If someone injects a thread early that causes user32.dll to load off the
// main thread this causes issues, so load it as soon as we've initialized
// the block-list. (See bug 1400637)
if (!sUser32BeforeBlocklist) {
::LoadLibraryW(L"user32.dll");
}
Kernel32Intercept.Init("kernel32.dll");
#ifdef _M_AMD64
if (!IsWin8OrLater()) {
// The crash that this hook works around is only seen on Win7.
stub_RtlInstallFunctionTableCallback.Set(
Kernel32Intercept, "RtlInstallFunctionTableCallback",
&patched_RtlInstallFunctionTableCallback);
}
#endif
// Bug 1361410: WRusr.dll will overwrite our hook and cause a crash.
// Workaround: If we detect WRusr.dll, don't hook.
if (!GetModuleHandleW(L"WRusr.dll")) {
if (!stub_BaseThreadInitThunk.SetDetour(Kernel32Intercept,
"BaseThreadInitThunk",
&patched_BaseThreadInitThunk)) {
#ifdef DEBUG
printf_stderr("BaseThreadInitThunk hook failed\n");
#endif
}
}
#if defined(NIGHTLY_BUILD)
// Populate a list of thread start addresses to block.
HMODULE hKernel = GetModuleHandleW(L"kernel32.dll");
if (hKernel) {
void* pProc;
pProc = (void*)GetProcAddress(hKernel, "LoadLibraryA");
if (pProc) {
Unused << gStartAddressesToBlock->append(pProc);
}
pProc = (void*)GetProcAddress(hKernel, "LoadLibraryW");
if (pProc) {
Unused << gStartAddressesToBlock->append(pProc);
}
pProc = (void*)GetProcAddress(hKernel, "LoadLibraryExA");
if (pProc) {
Unused << gStartAddressesToBlock->append(pProc);
}
pProc = (void*)GetProcAddress(hKernel, "LoadLibraryExW");
if (pProc) {
Unused << gStartAddressesToBlock->append(pProc);
}
}
#endif
}
#ifdef DEBUG
MFBT_API void DllBlocklist_Shutdown() {
if (IsUntrustedDllsHandlerEnabled()) {
glue::UntrustedDllsHandler::Shutdown();
}
}
#endif // DEBUG
static void WriteAnnotation(HANDLE aFile, Annotation aAnnotation,
const char* aValue, DWORD* aNumBytes) {
const char* str = AnnotationToString(aAnnotation);
WriteFile(aFile, str, strlen(str), aNumBytes, nullptr);
WriteFile(aFile, "=", 1, aNumBytes, nullptr);
WriteFile(aFile, aValue, strlen(aValue), aNumBytes, nullptr);
}
static void InternalWriteNotes(HANDLE file) {
DWORD nBytes;
WriteAnnotation(file, Annotation::BlockedDllList, "", &nBytes);
DllBlockSet::Write(file);
WriteFile(file, "\n", 1, &nBytes, nullptr);
if (sBlocklistInitFailed) {
WriteAnnotation(file, Annotation::BlocklistInitFailed, "1\n", &nBytes);
}
if (sUser32BeforeBlocklist) {
WriteAnnotation(file, Annotation::User32BeforeBlocklist, "1\n", &nBytes);
}
}
using WriterFn = void (*)(HANDLE);
static WriterFn gWriterFn = &InternalWriteNotes;
static void GetNativeNtBlockSetWriter() {
auto nativeWriter = reinterpret_cast<WriterFn>(
::GetProcAddress(::GetModuleHandleW(nullptr), "NativeNtBlockSet_Write"));
if (nativeWriter) {
gWriterFn = nativeWriter;
}
}
MFBT_API void DllBlocklist_WriteNotes(HANDLE file) {
MOZ_ASSERT(gWriterFn);
gWriterFn(file);
}
MFBT_API bool DllBlocklist_CheckStatus() {
if (sBlocklistInitFailed || sUser32BeforeBlocklist) return false;
return true;
}
// ============================================================================
// This section is for DLL Services
// ============================================================================
// These types are documented on MSDN but not provided in any SDK headers
enum DllNotificationReason {
LDR_DLL_NOTIFICATION_REASON_LOADED = 1,
LDR_DLL_NOTIFICATION_REASON_UNLOADED = 2
};
typedef struct _LDR_DLL_LOADED_NOTIFICATION_DATA {
ULONG Flags; // Reserved.
PCUNICODE_STRING FullDllName; // The full path name of the DLL module.
PCUNICODE_STRING BaseDllName; // The base file name of the DLL module.
PVOID DllBase; // A pointer to the base address for the DLL in memory.
ULONG SizeOfImage; // The size of the DLL image, in bytes.
} LDR_DLL_LOADED_NOTIFICATION_DATA, *PLDR_DLL_LOADED_NOTIFICATION_DATA;
typedef struct _LDR_DLL_UNLOADED_NOTIFICATION_DATA {
ULONG Flags; // Reserved.
PCUNICODE_STRING FullDllName; // The full path name of the DLL module.
PCUNICODE_STRING BaseDllName; // The base file name of the DLL module.
PVOID DllBase; // A pointer to the base address for the DLL in memory.
ULONG SizeOfImage; // The size of the DLL image, in bytes.
} LDR_DLL_UNLOADED_NOTIFICATION_DATA, *PLDR_DLL_UNLOADED_NOTIFICATION_DATA;
typedef union _LDR_DLL_NOTIFICATION_DATA {
LDR_DLL_LOADED_NOTIFICATION_DATA Loaded;
LDR_DLL_UNLOADED_NOTIFICATION_DATA Unloaded;
} LDR_DLL_NOTIFICATION_DATA, *PLDR_DLL_NOTIFICATION_DATA;
typedef const LDR_DLL_NOTIFICATION_DATA* PCLDR_DLL_NOTIFICATION_DATA;
typedef VOID(CALLBACK* PLDR_DLL_NOTIFICATION_FUNCTION)(
ULONG aReason, PCLDR_DLL_NOTIFICATION_DATA aNotificationData,
PVOID aContext);
NTSTATUS NTAPI LdrRegisterDllNotification(
ULONG aFlags, PLDR_DLL_NOTIFICATION_FUNCTION aCallback, PVOID aContext,
PVOID* aCookie);
static PVOID gNotificationCookie;
static VOID CALLBACK DllLoadNotification(
ULONG aReason, PCLDR_DLL_NOTIFICATION_DATA aNotificationData,
PVOID aContext) {
if (aReason != LDR_DLL_NOTIFICATION_REASON_LOADED) {
// We don't care about unloads
return;
}
glue::AutoSharedLock lock(gDllServicesLock);
if (!gDllServices) {
return;
}
PCUNICODE_STRING fullDllName = aNotificationData->Loaded.FullDllName;
gDllServices->DispatchDllLoadNotification(fullDllName);
}
namespace mozilla {
Authenticode* GetAuthenticode();
} // namespace mozilla
MFBT_API void DllBlocklist_SetFullDllServices(
mozilla::glue::detail::DllServicesBase* aSvc) {
glue::AutoExclusiveLock lock(gDllServicesLock);
if (aSvc) {
aSvc->SetAuthenticodeImpl(GetAuthenticode());
if (!gNotificationCookie) {
auto pLdrRegisterDllNotification =
reinterpret_cast<decltype(&::LdrRegisterDllNotification)>(
::GetProcAddress(::GetModuleHandleW(L"ntdll.dll"),
"LdrRegisterDllNotification"));
MOZ_DIAGNOSTIC_ASSERT(pLdrRegisterDllNotification);
mozilla::DebugOnly<NTSTATUS> ntStatus = pLdrRegisterDllNotification(
0, &DllLoadNotification, nullptr, &gNotificationCookie);
MOZ_ASSERT(NT_SUCCESS(ntStatus));
}
}
gDllServices = aSvc;
if (IsUntrustedDllsHandlerEnabled() && gDllServices) {
Vector<glue::ModuleLoadEvent, 0, InfallibleAllocPolicy> events;
if (glue::UntrustedDllsHandler::TakePendingEvents(events)) {
gDllServices->NotifyUntrustedModuleLoads(events);
}
}
}
MFBT_API void DllBlocklist_SetBasicDllServices(
mozilla::glue::detail::DllServicesBase* aSvc) {
if (!aSvc) {
return;
}
aSvc->SetAuthenticodeImpl(GetAuthenticode());
}
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