1 //===-- sanitizer_win_dll_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 // This file defines a family of thunks that should be statically linked into
9 // the DLLs that have instrumentation in order to delegate the calls to the
10 // shared runtime that lives in the main binary.
11 // See https://github.com/google/sanitizers/issues/209 for the details.
12 //===----------------------------------------------------------------------===//
13 
14 #ifdef SANITIZER_DLL_THUNK
15 #include "sanitizer_win_defs.h"
16 #include "sanitizer_win_dll_thunk.h"
17 #include "interception/interception.h"
18 
19 extern "C" {
20 void *WINAPI GetModuleHandleA(const char *module_name);
21 void abort();
22 }
23 
24 namespace __sanitizer {
25 uptr dllThunkGetRealAddrOrDie(const char *name) {
26   uptr ret =
27       __interception::InternalGetProcAddress((void *)GetModuleHandleA(0), name);
28   if (!ret)
29     abort();
30   return ret;
31 }
32 
33 int dllThunkIntercept(const char* main_function, uptr dll_function) {
34   uptr wrapper = dllThunkGetRealAddrOrDie(main_function);
35   if (!__interception::OverrideFunction(dll_function, wrapper, 0))
36     abort();
37   return 0;
38 }
39 
40 int dllThunkInterceptWhenPossible(const char* main_function,
41     const char* default_function, uptr dll_function) {
42   uptr wrapper = __interception::InternalGetProcAddress(
43     (void *)GetModuleHandleA(0), main_function);
44   if (!wrapper)
45     wrapper = dllThunkGetRealAddrOrDie(default_function);
46   if (!__interception::OverrideFunction(dll_function, wrapper, 0))
47     abort();
48   return 0;
49 }
50 } // namespace __sanitizer
51 
52 // Include Sanitizer Common interface.
53 #define INTERFACE_FUNCTION(Name) INTERCEPT_SANITIZER_FUNCTION(Name)
54 #define INTERFACE_WEAK_FUNCTION(Name) INTERCEPT_SANITIZER_WEAK_FUNCTION(Name)
55 #include "sanitizer_common_interface.inc"
56 
57 #pragma section(".DLLTH$A", read)
58 #pragma section(".DLLTH$Z", read)
59 
60 typedef void (*DllThunkCB)();
61 extern "C" {
62 __declspec(allocate(".DLLTH$A")) DllThunkCB __start_dll_thunk;
63 __declspec(allocate(".DLLTH$Z")) DllThunkCB __stop_dll_thunk;
64 }
65 
66 // Disable compiler warnings that show up if we declare our own version
67 // of a compiler intrinsic (e.g. strlen).
68 #pragma warning(disable: 4391)
69 #pragma warning(disable: 4392)
70 
71 extern "C" int __dll_thunk_init() {
72   static bool flag = false;
73   // __dll_thunk_init is expected to be called by only one thread.
74   if (flag) return 0;
75   flag = true;
76 
77   for (DllThunkCB *it = &__start_dll_thunk; it < &__stop_dll_thunk; ++it)
78     if (*it)
79       (*it)();
80 
81   // In DLLs, the callbacks are expected to return 0,
82   // otherwise CRT initialization fails.
83   return 0;
84 }
85 
86 // We want to call dll_thunk_init before C/C++ initializers / constructors are
87 // executed, otherwise functions like memset might be invoked.
88 #pragma section(".CRT$XIB", long, read)
89 __declspec(allocate(".CRT$XIB")) int (*__dll_thunk_preinit)() =
90     __dll_thunk_init;
91 
92 static void WINAPI dll_thunk_thread_init(void *mod, unsigned long reason,
93                                          void *reserved) {
94   if (reason == /*DLL_PROCESS_ATTACH=*/1) __dll_thunk_init();
95 }
96 
97 #pragma section(".CRT$XLAB", long, read)
98 __declspec(allocate(".CRT$XLAB")) void (WINAPI *__dll_thunk_tls_init)(void *,
99     unsigned long, void *) = dll_thunk_thread_init;
100 
101 #endif // SANITIZER_DLL_THUNK
102