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.
53 extern "C" {
54 __declspec(dllimport) int __asan_should_detect_stack_use_after_return();
55 int __asan_option_detect_stack_use_after_return;
56
57 __declspec(dllimport) void* __asan_get_shadow_memory_dynamic_address();
58 void* __asan_shadow_memory_dynamic_address;
59 }
60
InitializeClonedVariables()61 static 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
asan_thread_init(void * mod,unsigned long reason,void * reserved)69 static 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.
91 extern "C" int __cdecl atexit(void (__cdecl *f)(void));
92 extern "C" void __cdecl _initterm(void *a, void *b);
93
94 namespace {
95 __declspec(allocate(".CRT$XTW")) void* before_global_dtors = 0;
96 __declspec(allocate(".CRT$XTY")) void* after_global_dtors = 0;
97
UnregisterGlobals()98 void UnregisterGlobals() {
99 _initterm(&before_global_dtors, &after_global_dtors);
100 }
101
ScheduleUnregisterGlobals()102 int 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"))
112 int (*__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).
118 extern "C" {
119 __declspec(dllimport) int __asan_set_seh_filter();
SetSEHFilter()120 static 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
128 WIN_FORCE_LINK(__asan_dso_reg_hook)
129
130 #endif // SANITIZER_DYNAMIC_RUNTIME_THUNK
131