1//===-- asan_win.cpp ------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file is a part of AddressSanitizer, an address sanity checker.
10//
11// Windows-specific details.
12//===----------------------------------------------------------------------===//
13
14#include "sanitizer_common/sanitizer_platform.h"
15#if SANITIZER_WINDOWS
16#define WIN32_LEAN_AND_MEAN
17#include <windows.h>
18
19#include <stdlib.h>
20
21#include "asan_interceptors.h"
22#include "asan_internal.h"
23#include "asan_mapping.h"
24#include "asan_report.h"
25#include "asan_stack.h"
26#include "asan_thread.h"
27#include "sanitizer_common/sanitizer_libc.h"
28#include "sanitizer_common/sanitizer_mutex.h"
29#include "sanitizer_common/sanitizer_win.h"
30#include "sanitizer_common/sanitizer_win_defs.h"
31
32using namespace __asan;
33
34extern "C" {
35SANITIZER_INTERFACE_ATTRIBUTE
36int __asan_should_detect_stack_use_after_return() {
37  __asan_init();
38  return __asan_option_detect_stack_use_after_return;
39}
40
41SANITIZER_INTERFACE_ATTRIBUTE
42uptr __asan_get_shadow_memory_dynamic_address() {
43  __asan_init();
44  return __asan_shadow_memory_dynamic_address;
45}
46}  // extern "C"
47
48// ---------------------- Windows-specific interceptors ---------------- {{{
49static LPTOP_LEVEL_EXCEPTION_FILTER default_seh_handler;
50static LPTOP_LEVEL_EXCEPTION_FILTER user_seh_handler;
51
52extern "C" SANITIZER_INTERFACE_ATTRIBUTE
53long __asan_unhandled_exception_filter(EXCEPTION_POINTERS *info) {
54  EXCEPTION_RECORD *exception_record = info->ExceptionRecord;
55  CONTEXT *context = info->ContextRecord;
56
57  // FIXME: Handle EXCEPTION_STACK_OVERFLOW here.
58
59  SignalContext sig(exception_record, context);
60  ReportDeadlySignal(sig);
61  UNREACHABLE("returned from reporting deadly signal");
62}
63
64// Wrapper SEH Handler. If the exception should be handled by asan, we call
65// __asan_unhandled_exception_filter, otherwise, we execute the user provided
66// exception handler or the default.
67static long WINAPI SEHHandler(EXCEPTION_POINTERS *info) {
68  DWORD exception_code = info->ExceptionRecord->ExceptionCode;
69  if (__sanitizer::IsHandledDeadlyException(exception_code))
70    return __asan_unhandled_exception_filter(info);
71  if (user_seh_handler)
72    return user_seh_handler(info);
73  // Bubble out to the default exception filter.
74  if (default_seh_handler)
75    return default_seh_handler(info);
76  return EXCEPTION_CONTINUE_SEARCH;
77}
78
79INTERCEPTOR_WINAPI(LPTOP_LEVEL_EXCEPTION_FILTER, SetUnhandledExceptionFilter,
80                   LPTOP_LEVEL_EXCEPTION_FILTER ExceptionFilter) {
81  CHECK(REAL(SetUnhandledExceptionFilter));
82  if (ExceptionFilter == &SEHHandler)
83    return REAL(SetUnhandledExceptionFilter)(ExceptionFilter);
84  // We record the user provided exception handler to be called for all the
85  // exceptions unhandled by asan.
86  Swap(ExceptionFilter, user_seh_handler);
87  return ExceptionFilter;
88}
89
90INTERCEPTOR_WINAPI(void, RtlRaiseException, EXCEPTION_RECORD *ExceptionRecord) {
91  CHECK(REAL(RtlRaiseException));
92  // This is a noreturn function, unless it's one of the exceptions raised to
93  // communicate with the debugger, such as the one from OutputDebugString.
94  if (ExceptionRecord->ExceptionCode != DBG_PRINTEXCEPTION_C)
95    __asan_handle_no_return();
96  REAL(RtlRaiseException)(ExceptionRecord);
97}
98
99INTERCEPTOR_WINAPI(void, RaiseException, void *a, void *b, void *c, void *d) {
100  CHECK(REAL(RaiseException));
101  __asan_handle_no_return();
102  REAL(RaiseException)(a, b, c, d);
103}
104
105#ifdef _WIN64
106
107INTERCEPTOR_WINAPI(EXCEPTION_DISPOSITION, __C_specific_handler,
108                   _EXCEPTION_RECORD *a, void *b, _CONTEXT *c,
109                   _DISPATCHER_CONTEXT *d) {
110  CHECK(REAL(__C_specific_handler));
111  __asan_handle_no_return();
112  return REAL(__C_specific_handler)(a, b, c, d);
113}
114
115#else
116
117INTERCEPTOR(int, _except_handler3, void *a, void *b, void *c, void *d) {
118  CHECK(REAL(_except_handler3));
119  __asan_handle_no_return();
120  return REAL(_except_handler3)(a, b, c, d);
121}
122
123#if ASAN_DYNAMIC
124// This handler is named differently in -MT and -MD CRTs.
125#define _except_handler4 _except_handler4_common
126#endif
127INTERCEPTOR(int, _except_handler4, void *a, void *b, void *c, void *d) {
128  CHECK(REAL(_except_handler4));
129  __asan_handle_no_return();
130  return REAL(_except_handler4)(a, b, c, d);
131}
132#endif
133
134static thread_return_t THREAD_CALLING_CONV asan_thread_start(void *arg) {
135  AsanThread *t = (AsanThread *)arg;
136  SetCurrentThread(t);
137  return t->ThreadStart(GetTid());
138}
139
140INTERCEPTOR_WINAPI(HANDLE, CreateThread, LPSECURITY_ATTRIBUTES security,
141                   SIZE_T stack_size, LPTHREAD_START_ROUTINE start_routine,
142                   void *arg, DWORD thr_flags, DWORD *tid) {
143  // Strict init-order checking is thread-hostile.
144  if (flags()->strict_init_order)
145    StopInitOrderChecking();
146  GET_STACK_TRACE_THREAD;
147  // FIXME: The CreateThread interceptor is not the same as a pthread_create
148  // one.  This is a bandaid fix for PR22025.
149  bool detached = false;  // FIXME: how can we determine it on Windows?
150  u32 current_tid = GetCurrentTidOrInvalid();
151  AsanThread *t =
152      AsanThread::Create(start_routine, arg, current_tid, &stack, detached);
153  return REAL(CreateThread)(security, stack_size, asan_thread_start, t,
154                            thr_flags, tid);
155}
156
157// }}}
158
159namespace __asan {
160
161void InitializePlatformInterceptors() {
162  // The interceptors were not designed to be removable, so we have to keep this
163  // module alive for the life of the process.
164  HMODULE pinned;
165  CHECK(GetModuleHandleExW(
166      GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_PIN,
167      (LPCWSTR)&InitializePlatformInterceptors, &pinned));
168
169  ASAN_INTERCEPT_FUNC(CreateThread);
170  ASAN_INTERCEPT_FUNC(SetUnhandledExceptionFilter);
171
172#ifdef _WIN64
173  ASAN_INTERCEPT_FUNC(__C_specific_handler);
174#else
175  ASAN_INTERCEPT_FUNC(_except_handler3);
176  ASAN_INTERCEPT_FUNC(_except_handler4);
177#endif
178
179  // Try to intercept kernel32!RaiseException, and if that fails, intercept
180  // ntdll!RtlRaiseException instead.
181  if (!::__interception::OverrideFunction("RaiseException",
182                                          (uptr)WRAP(RaiseException),
183                                          (uptr *)&REAL(RaiseException))) {
184    CHECK(::__interception::OverrideFunction("RtlRaiseException",
185                                             (uptr)WRAP(RtlRaiseException),
186                                             (uptr *)&REAL(RtlRaiseException)));
187  }
188}
189
190void AsanApplyToGlobals(globals_op_fptr op, const void *needle) {
191  UNIMPLEMENTED();
192}
193
194void FlushUnneededASanShadowMemory(uptr p, uptr size) {
195  // Since asan's mapping is compacting, the shadow chunk may be
196  // not page-aligned, so we only flush the page-aligned portion.
197  ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size));
198}
199
200// ---------------------- TSD ---------------- {{{
201static bool tsd_key_inited = false;
202
203static __declspec(thread) void *fake_tsd = 0;
204
205// https://docs.microsoft.com/en-us/windows/desktop/api/winternl/ns-winternl-_teb
206// "[This structure may be altered in future versions of Windows. Applications
207// should use the alternate functions listed in this topic.]"
208typedef struct _TEB {
209  PVOID Reserved1[12];
210  // PVOID ThreadLocalStoragePointer; is here, at the last field in Reserved1.
211  PVOID ProcessEnvironmentBlock;
212  PVOID Reserved2[399];
213  BYTE Reserved3[1952];
214  PVOID TlsSlots[64];
215  BYTE Reserved4[8];
216  PVOID Reserved5[26];
217  PVOID ReservedForOle;
218  PVOID Reserved6[4];
219  PVOID TlsExpansionSlots;
220} TEB, *PTEB;
221
222constexpr size_t TEB_RESERVED_FIELDS_THREAD_LOCAL_STORAGE_OFFSET = 11;
223BOOL IsTlsInitialized() {
224  PTEB teb = (PTEB)NtCurrentTeb();
225  return teb->Reserved1[TEB_RESERVED_FIELDS_THREAD_LOCAL_STORAGE_OFFSET] !=
226         nullptr;
227}
228
229void AsanTSDInit(void (*destructor)(void *tsd)) {
230  // FIXME: we're ignoring the destructor for now.
231  tsd_key_inited = true;
232}
233
234void *AsanTSDGet() {
235  CHECK(tsd_key_inited);
236  return IsTlsInitialized() ? fake_tsd : nullptr;
237}
238
239void AsanTSDSet(void *tsd) {
240  CHECK(tsd_key_inited);
241  fake_tsd = tsd;
242}
243
244void PlatformTSDDtor(void *tsd) { AsanThread::TSDDtor(tsd); }
245// }}}
246
247// ---------------------- Various stuff ---------------- {{{
248void *AsanDoesNotSupportStaticLinkage() {
249#if defined(_DEBUG)
250#error Please build the runtime with a non-debug CRT: /MD or /MT
251#endif
252  return 0;
253}
254
255uptr FindDynamicShadowStart() {
256  return MapDynamicShadow(MemToShadowSize(kHighMemEnd), SHADOW_SCALE,
257                          /*min_shadow_base_alignment*/ 0, kHighMemEnd);
258}
259
260void AsanCheckDynamicRTPrereqs() {}
261
262void AsanCheckIncompatibleRT() {}
263
264void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
265  UNIMPLEMENTED();
266}
267
268void AsanOnDeadlySignal(int, void *siginfo, void *context) { UNIMPLEMENTED(); }
269
270bool PlatformUnpoisonStacks() { return false; }
271
272#if SANITIZER_WINDOWS64
273// Exception handler for dealing with shadow memory.
274static LONG CALLBACK
275ShadowExceptionHandler(PEXCEPTION_POINTERS exception_pointers) {
276  uptr page_size = GetPageSizeCached();
277  // Only handle access violations.
278  if (exception_pointers->ExceptionRecord->ExceptionCode !=
279          EXCEPTION_ACCESS_VIOLATION ||
280      exception_pointers->ExceptionRecord->NumberParameters < 2) {
281    __asan_handle_no_return();
282    return EXCEPTION_CONTINUE_SEARCH;
283  }
284
285  // Only handle access violations that land within the shadow memory.
286  uptr addr =
287      (uptr)(exception_pointers->ExceptionRecord->ExceptionInformation[1]);
288
289  // Check valid shadow range.
290  if (!AddrIsInShadow(addr)) {
291    __asan_handle_no_return();
292    return EXCEPTION_CONTINUE_SEARCH;
293  }
294
295  // This is an access violation while trying to read from the shadow. Commit
296  // the relevant page and let execution continue.
297
298  // Determine the address of the page that is being accessed.
299  uptr page = RoundDownTo(addr, page_size);
300
301  // Commit the page.
302  uptr result =
303      (uptr)::VirtualAlloc((LPVOID)page, page_size, MEM_COMMIT, PAGE_READWRITE);
304  if (result != page)
305    return EXCEPTION_CONTINUE_SEARCH;
306
307  // The page mapping succeeded, so continue execution as usual.
308  return EXCEPTION_CONTINUE_EXECUTION;
309}
310
311#endif
312
313void InitializePlatformExceptionHandlers() {
314#if SANITIZER_WINDOWS64
315  // On Win64, we map memory on demand with access violation handler.
316  // Install our exception handler.
317  CHECK(AddVectoredExceptionHandler(TRUE, &ShadowExceptionHandler));
318#endif
319}
320
321bool IsSystemHeapAddress(uptr addr) {
322  return ::HeapValidate(GetProcessHeap(), 0, (void *)addr) != FALSE;
323}
324
325// We want to install our own exception handler (EH) to print helpful reports
326// on access violations and whatnot.  Unfortunately, the CRT initializers assume
327// they are run before any user code and drop any previously-installed EHs on
328// the floor, so we can't install our handler inside __asan_init.
329// (See crt0dat.c in the CRT sources for the details)
330//
331// Things get even more complicated with the dynamic runtime, as it finishes its
332// initialization before the .exe module CRT begins to initialize.
333//
334// For the static runtime (-MT), it's enough to put a callback to
335// __asan_set_seh_filter in the last section for C initializers.
336//
337// For the dynamic runtime (-MD), we want link the same
338// asan_dynamic_runtime_thunk.lib to all the modules, thus __asan_set_seh_filter
339// will be called for each instrumented module.  This ensures that at least one
340// __asan_set_seh_filter call happens after the .exe module CRT is initialized.
341extern "C" SANITIZER_INTERFACE_ATTRIBUTE int __asan_set_seh_filter() {
342  // We should only store the previous handler if it's not our own handler in
343  // order to avoid loops in the EH chain.
344  auto prev_seh_handler = SetUnhandledExceptionFilter(SEHHandler);
345  if (prev_seh_handler != &SEHHandler)
346    default_seh_handler = prev_seh_handler;
347  return 0;
348}
349
350bool HandleDlopenInit() {
351  // Not supported on this platform.
352  static_assert(!SANITIZER_SUPPORTS_INIT_FOR_DLOPEN,
353                "Expected SANITIZER_SUPPORTS_INIT_FOR_DLOPEN to be false");
354  return false;
355}
356
357#if !ASAN_DYNAMIC
358// The CRT runs initializers in this order:
359// - C initializers, from XIA to XIZ
360// - C++ initializers, from XCA to XCZ
361// Prior to 2015, the CRT set the unhandled exception filter at priority XIY,
362// near the end of C initialization. Starting in 2015, it was moved to the
363// beginning of C++ initialization. We set our priority to XCAB to run
364// immediately after the CRT runs. This way, our exception filter is called
365// first and we can delegate to their filter if appropriate.
366#pragma section(".CRT$XCAB", long, read)
367__declspec(allocate(".CRT$XCAB")) int (*__intercept_seh)() =
368    __asan_set_seh_filter;
369
370// Piggyback on the TLS initialization callback directory to initialize asan as
371// early as possible. Initializers in .CRT$XL* are called directly by ntdll,
372// which run before the CRT. Users also add code to .CRT$XLC, so it's important
373// to run our initializers first.
374static void NTAPI asan_thread_init(void *module, DWORD reason, void *reserved) {
375  if (reason == DLL_PROCESS_ATTACH)
376    __asan_init();
377}
378
379#pragma section(".CRT$XLAB", long, read)
380__declspec(allocate(".CRT$XLAB")) void(NTAPI *__asan_tls_init)(
381    void *, unsigned long, void *) = asan_thread_init;
382#endif
383
384static void NTAPI asan_thread_exit(void *module, DWORD reason, void *reserved) {
385  if (reason == DLL_THREAD_DETACH) {
386    // Unpoison the thread's stack because the memory may be re-used.
387    NT_TIB *tib = (NT_TIB *)NtCurrentTeb();
388    uptr stackSize = (uptr)tib->StackBase - (uptr)tib->StackLimit;
389    __asan_unpoison_memory_region(tib->StackLimit, stackSize);
390  }
391}
392
393#pragma section(".CRT$XLY", long, read)
394__declspec(allocate(".CRT$XLY")) void(NTAPI *__asan_tls_exit)(
395    void *, unsigned long, void *) = asan_thread_exit;
396
397WIN_FORCE_LINK(__asan_dso_reg_hook)
398
399// }}}
400}  // namespace __asan
401
402#endif  // SANITIZER_WINDOWS
403