libsanitizer/interception/interception_win.cc

   1 //===-- interception_linux.cc -----------------------------------*- C++ -*-===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is a part of AddressSanitizer, an address sanity checker.
   9 //
  10 // Windows-specific interception methods.
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifdef _WIN32
  14
  15 #include "interception.h"
  16 #include <windows.h>
  17
  18 namespace __interception {
  19
  20 bool GetRealFunctionAddress(const char *func_name, uptr *func_addr) {
  21   const char *DLLS[] = {
  22     "msvcr80.dll",
  23     "msvcr90.dll",
  24     "kernel32.dll",
  25     NULL
  26   };
  27   *func_addr = 0;
  28   for (size_t i = 0; *func_addr == 0 && DLLS[i]; ++i) {
  29     *func_addr = (uptr)GetProcAddress(GetModuleHandleA(DLLS[i]), func_name);
  30   }
  31   return (*func_addr != 0);
  32 }
  33
  34 // FIXME: internal_str* and internal_mem* functions should be moved from the
  35 // ASan sources into interception/.
  36
  37 static void _memset(void *p, int value, size_t sz) {
  38   for (size_t i = 0; i < sz; ++i)
  39     ((char*)p)[i] = (char)value;
  40 }
  41
  42 static void _memcpy(void *dst, void *src, size_t sz) {
  43   char *dst_c = (char*)dst,
  44        *src_c = (char*)src;
  45   for (size_t i = 0; i < sz; ++i)
  46     dst_c[i] = src_c[i];
  47 }
  48
  49 static void WriteJumpInstruction(char *jmp_from, char *to) {
  50   // jmp XXYYZZWW = E9 WW ZZ YY XX, where XXYYZZWW is an offset fromt jmp_from
  51   // to the next instruction to the destination.
  52   ptrdiff_t offset = to - jmp_from - 5;
  53   *jmp_from = '\xE9';
  54   *(ptrdiff_t*)(jmp_from + 1) = offset;
  55 }
  56
  57 static char *GetMemoryForTrampoline(size_t size) {
  58   // Trampolines are allocated from a common pool.
  59   const int POOL_SIZE = 1024;
  60   static char *pool = NULL;
  61   static size_t pool_used = 0;
  62   if (!pool) {
  63     pool = (char *)VirtualAlloc(NULL, POOL_SIZE, MEM_RESERVE | MEM_COMMIT,
  64                                 PAGE_EXECUTE_READWRITE);
  65     // FIXME: Might want to apply PAGE_EXECUTE_READ access after all the
  66     // interceptors are in place.
  67     if (!pool)
  68       return NULL;
  69     _memset(pool, 0xCC /* int 3 */, POOL_SIZE);
  70   }
  71
  72   if (pool_used + size > POOL_SIZE)
  73     return NULL;
  74
  75   char *ret = pool + pool_used;
  76   pool_used += size;
  77   return ret;
  78 }
  79
  80 // Returns 0 on error.
  81 static size_t RoundUpToInstrBoundary(size_t size, char *code) {
  82   size_t cursor = 0;
  83   while (cursor < size) {
  84     switch (code[cursor]) {
  85       case '\x51':  // push ecx
  86       case '\x52':  // push edx
  87       case '\x53':  // push ebx
  88       case '\x54':  // push esp
  89       case '\x55':  // push ebp
  90       case '\x56':  // push esi
  91       case '\x57':  // push edi
  92       case '\x5D':  // pop ebp
  93         cursor++;
  94         continue;
  95       case '\x6A':  // 6A XX = push XX
  96         cursor += 2;
  97         continue;
  98       case '\xE9':  // E9 XX YY ZZ WW = jmp WWZZYYXX
  99         cursor += 5;
 100         continue;
 101     }
 102     switch (*(unsigned short*)(code + cursor)) {  // NOLINT
 103       case 0xFF8B:  // 8B FF = mov edi, edi
 104       case 0xEC8B:  // 8B EC = mov ebp, esp
 105       case 0xC033:  // 33 C0 = xor eax, eax
 106         cursor += 2;
 107         continue;
 108       case 0x458B:  // 8B 45 XX = mov eax, dword ptr [ebp+XXh]
 109       case 0x5D8B:  // 8B 5D XX = mov ebx, dword ptr [ebp+XXh]
 110       case 0xEC83:  // 83 EC XX = sub esp, XX
 111         cursor += 3;
 112         continue;
 113       case 0xC1F7:  // F7 C1 XX YY ZZ WW = test ecx, WWZZYYXX
 114         cursor += 6;
 115         continue;
 116       case 0x3D83:  // 83 3D XX YY ZZ WW TT = cmp TT, WWZZYYXX
 117         cursor += 7;
 118         continue;
 119     }
 120     switch (0x00FFFFFF & *(unsigned int*)(code + cursor)) {
 121       case 0x24448A:  // 8A 44 24 XX = mov eal, dword ptr [esp+XXh]
 122       case 0x244C8B:  // 8B 4C 24 XX = mov ecx, dword ptr [esp+XXh]
 123       case 0x24548B:  // 8B 54 24 XX = mov edx, dword ptr [esp+XXh]
 124       case 0x24748B:  // 8B 74 24 XX = mov esi, dword ptr [esp+XXh]
 125       case 0x247C8B:  // 8B 7C 24 XX = mov edi, dword ptr [esp+XXh]
 126         cursor += 4;
 127         continue;
 128     }
 129
 130     // Unknown instruction!
 131     // FIXME: Unknown instruction failures might happen when we add a new
 132     // interceptor or a new compiler version. In either case, they should result
 133     // in visible and readable error messages. However, merely calling abort()
 134     // or __debugbreak() leads to an infinite recursion in CheckFailed.
 135     // Do we have a good way to abort with an error message here?
 136     return 0;
 137   }
 138
 139   return cursor;
 140 }
 141
 142 bool OverrideFunction(uptr old_func, uptr new_func, uptr *orig_old_func) {
 143 #ifdef _WIN64
 144 #error OverrideFunction is not yet supported on x64
 145 #endif
 146   // Function overriding works basically like this:
 147   // We write "jmp <new_func>" (5 bytes) at the beginning of the 'old_func'
 148   // to override it.
 149   // We might want to be able to execute the original 'old_func' from the
 150   // wrapper, in this case we need to keep the leading 5+ bytes ('head')
 151   // of the original code somewhere with a "jmp <old_func+head>".
 152   // We call these 'head'+5 bytes of instructions a "trampoline".
 153   char *old_bytes = (char *)old_func;
 154
 155   // We'll need at least 5 bytes for a 'jmp'.
 156   size_t head = 5;
 157   if (orig_old_func) {
 158     // Find out the number of bytes of the instructions we need to copy
 159     // to the trampoline and store it in 'head'.
 160     head = RoundUpToInstrBoundary(head, old_bytes);
 161     if (!head)
 162       return false;
 163
 164     // Put the needed instructions into the trampoline bytes.
 165     char *trampoline = GetMemoryForTrampoline(head + 5);
 166     if (!trampoline)
 167       return false;
 168     _memcpy(trampoline, old_bytes, head);
 169     WriteJumpInstruction(trampoline + head, old_bytes + head);
 170     *orig_old_func = (uptr)trampoline;
 171   }
 172
 173   // Now put the "jmp <new_func>" instruction at the original code location.
 174   // We should preserve the EXECUTE flag as some of our own code might be
 175   // located in the same page (sic!).  FIXME: might consider putting the
 176   // __interception code into a separate section or something?
 177   DWORD old_prot, unused_prot;
 178   if (!VirtualProtect((void *)old_bytes, head, PAGE_EXECUTE_READWRITE,
 179                       &old_prot))
 180     return false;
 181
 182   WriteJumpInstruction(old_bytes, (char *)new_func);
 183   _memset(old_bytes + 5, 0xCC /* int 3 */, head - 5);
 184
 185   // Restore the original permissions.
 186   if (!VirtualProtect((void *)old_bytes, head, old_prot, &unused_prot))
 187     return false;  // not clear if this failure bothers us.
 188
 189   return true;
 190 }
 191
 192 }  // namespace __interception
 193
 194 #endif  // _WIN32