asan_win_dynamic_runtime_thunk.cpp revision 360784
1//===-- asan_win_dynamic_runtime_thunk.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// This file defines things that need to be present in the application modules 12// to interact with the ASan DLL runtime correctly and can't be implemented 13// using the default "import library" generated when linking the DLL RTL. 14// 15// This includes: 16// - creating weak aliases to default implementation imported from asan dll. 17// - forwarding the detect_stack_use_after_return runtime option 18// - working around deficiencies of the MD runtime 19// - installing a custom SEH handler 20// 21//===----------------------------------------------------------------------===// 22 23#ifdef SANITIZER_DYNAMIC_RUNTIME_THUNK 24#define SANITIZER_IMPORT_INTERFACE 1 25#include "sanitizer_common/sanitizer_win_defs.h" 26#define WIN32_LEAN_AND_MEAN 27#include <windows.h> 28 29// Define weak alias for all weak functions imported from asan dll. 30#define INTERFACE_FUNCTION(Name) 31#define INTERFACE_WEAK_FUNCTION(Name) WIN_WEAK_IMPORT_DEF(Name) 32#include "asan_interface.inc" 33 34// First, declare CRT sections we'll be using in this file 35#pragma section(".CRT$XIB", long, read) 36#pragma section(".CRT$XID", long, read) 37#pragma section(".CRT$XCAB", long, read) 38#pragma section(".CRT$XTW", long, read) 39#pragma section(".CRT$XTY", long, read) 40#pragma section(".CRT$XLAB", long, read) 41 42//////////////////////////////////////////////////////////////////////////////// 43// Define a copy of __asan_option_detect_stack_use_after_return that should be 44// used when linking an MD runtime with a set of object files on Windows. 45// 46// The ASan MD runtime dllexports '__asan_option_detect_stack_use_after_return', 47// so normally we would just dllimport it. Unfortunately, the dllimport 48// attribute adds __imp_ prefix to the symbol name of a variable. 49// Since in general we don't know if a given TU is going to be used 50// with a MT or MD runtime and we don't want to use ugly __imp_ names on Windows 51// just to work around this issue, let's clone the variable that is constant 52// after initialization anyways. 53extern "C" { 54__declspec(dllimport) int __asan_should_detect_stack_use_after_return(); 55int __asan_option_detect_stack_use_after_return; 56 57__declspec(dllimport) void* __asan_get_shadow_memory_dynamic_address(); 58void* __asan_shadow_memory_dynamic_address; 59} 60 61static int InitializeClonedVariables() { 62 __asan_option_detect_stack_use_after_return = 63 __asan_should_detect_stack_use_after_return(); 64 __asan_shadow_memory_dynamic_address = 65 __asan_get_shadow_memory_dynamic_address(); 66 return 0; 67} 68 69static void NTAPI asan_thread_init(void *mod, unsigned long reason, 70 void *reserved) { 71 if (reason == DLL_PROCESS_ATTACH) InitializeClonedVariables(); 72} 73 74// Our cloned variables must be initialized before C/C++ constructors. If TLS 75// is used, our .CRT$XLAB initializer will run first. If not, our .CRT$XIB 76// initializer is needed as a backup. 77__declspec(allocate(".CRT$XIB")) int (*__asan_initialize_cloned_variables)() = 78 InitializeClonedVariables; 79__declspec(allocate(".CRT$XLAB")) void (NTAPI *__asan_tls_init)(void *, 80 unsigned long, void *) = asan_thread_init; 81 82//////////////////////////////////////////////////////////////////////////////// 83// For some reason, the MD CRT doesn't call the C/C++ terminators during on DLL 84// unload or on exit. ASan relies on LLVM global_dtors to call 85// __asan_unregister_globals on these events, which unfortunately doesn't work 86// with the MD runtime, see PR22545 for the details. 87// To work around this, for each DLL we schedule a call to UnregisterGlobals 88// using atexit() that calls a small subset of C terminators 89// where LLVM global_dtors is placed. Fingers crossed, no other C terminators 90// are there. 91extern "C" int __cdecl atexit(void (__cdecl *f)(void)); 92extern "C" void __cdecl _initterm(void *a, void *b); 93 94namespace { 95__declspec(allocate(".CRT$XTW")) void* before_global_dtors = 0; 96__declspec(allocate(".CRT$XTY")) void* after_global_dtors = 0; 97 98void UnregisterGlobals() { 99 _initterm(&before_global_dtors, &after_global_dtors); 100} 101 102int ScheduleUnregisterGlobals() { 103 return atexit(UnregisterGlobals); 104} 105} // namespace 106 107// We need to call 'atexit(UnregisterGlobals);' as early as possible, but after 108// atexit() is initialized (.CRT$XIC). As this is executed before C++ 109// initializers (think ctors for globals), UnregisterGlobals gets executed after 110// dtors for C++ globals. 111__declspec(allocate(".CRT$XID")) 112int (*__asan_schedule_unregister_globals)() = ScheduleUnregisterGlobals; 113 114//////////////////////////////////////////////////////////////////////////////// 115// ASan SEH handling. 116// We need to set the ASan-specific SEH handler at the end of CRT initialization 117// of each module (see also asan_win.cpp). 118extern "C" { 119__declspec(dllimport) int __asan_set_seh_filter(); 120static int SetSEHFilter() { return __asan_set_seh_filter(); } 121 122// Unfortunately, putting a pointer to __asan_set_seh_filter into 123// __asan_intercept_seh gets optimized out, so we have to use an extra function. 124__declspec(allocate(".CRT$XCAB")) int (*__asan_seh_interceptor)() = 125 SetSEHFilter; 126} 127 128WIN_FORCE_LINK(__asan_dso_reg_hook) 129 130#endif // SANITIZER_DYNAMIC_RUNTIME_THUNK 131