sandbox/win/src/service_resolver_32.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "sandbox/win/src/service_resolver.h"
   6
   7 #include "base/memory/scoped_ptr.h"
   8 #include "sandbox/win/src/win_utils.h"
   9
  10 namespace {
  11 #pragma pack(push, 1)
  12
  13 const BYTE kMovEax = 0xB8;
  14 const BYTE kMovEdx = 0xBA;
  15 const USHORT kMovEdxEsp = 0xD48B;
  16 const USHORT kCallPtrEdx = 0x12FF;
  17 const USHORT kCallEdx = 0xD2FF;
  18 const BYTE kCallEip = 0xE8;
  19 const BYTE kRet = 0xC2;
  20 const BYTE kRet2 = 0xC3;
  21 const BYTE kNop = 0x90;
  22 const USHORT kJmpEdx = 0xE2FF;
  23 const USHORT kXorEcx = 0xC933;
  24 const ULONG kLeaEdx = 0x0424548D;
  25 const ULONG kCallFs1 = 0xC015FF64;
  26 const USHORT kCallFs2 = 0;
  27 const BYTE kCallFs3 = 0;
  28 const BYTE kAddEsp1 = 0x83;
  29 const USHORT kAddEsp2 = 0x4C4;
  30 const BYTE kJmp32 = 0xE9;
  31 const USHORT kSysenter = 0x340F;
  32
  33 const int kMaxService = 1000;
  34
  35 // Service code for 32 bit systems.
  36 // NOTE: on win2003 "call dword ptr [edx]" is "call edx".
  37 struct ServiceEntry {
  38   // This struct contains roughly the following code:
  39   // 00 mov     eax,25h
  40   // 05 mov     edx,offset SharedUserData!SystemCallStub (7ffe0300)
  41   // 0a call    dword ptr [edx]
  42   // 0c ret     2Ch
  43   // 0f nop
  44   BYTE mov_eax;         // = B8
  45   ULONG service_id;
  46   BYTE mov_edx;         // = BA
  47   ULONG stub;
  48   USHORT call_ptr_edx;  // = FF 12
  49   BYTE ret;             // = C2
  50   USHORT num_params;
  51   BYTE nop;
  52 };
  53
  54 // Service code for 32 bit Windows 8.
  55 struct ServiceEntryW8 {
  56   // This struct contains the following code:
  57   // 00 b825000000      mov     eax,25h
  58   // 05 e803000000      call    eip+3
  59   // 0a c22c00          ret     2Ch
  60   // 0d 8bd4            mov     edx,esp
  61   // 0f 0f34            sysenter
  62   // 11 c3              ret
  63   // 12 8bff            mov     edi,edi
  64   BYTE mov_eax;         // = B8
  65   ULONG service_id;
  66   BYTE call_eip;        // = E8
  67   ULONG call_offset;
  68   BYTE ret_p;           // = C2
  69   USHORT num_params;
  70   USHORT mov_edx_esp;   // = BD D4
  71   USHORT sysenter;      // = 0F 34
  72   BYTE ret;             // = C3
  73   USHORT nop;
  74 };
  75
  76 // Service code for a 32 bit process running on a 64 bit os.
  77 struct Wow64Entry {
  78   // This struct may contain one of two versions of code:
  79   // 1. For XP, Vista and 2K3:
  80   // 00 b825000000      mov     eax, 25h
  81   // 05 33c9            xor     ecx, ecx
  82   // 07 8d542404        lea     edx, [esp + 4]
  83   // 0b 64ff15c0000000  call    dword ptr fs:[0C0h]
  84   // 12 c22c00          ret     2Ch
  85   //
  86   // 2. For Windows 7:
  87   // 00 b825000000      mov     eax, 25h
  88   // 05 33c9            xor     ecx, ecx
  89   // 07 8d542404        lea     edx, [esp + 4]
  90   // 0b 64ff15c0000000  call    dword ptr fs:[0C0h]
  91   // 12 83c404          add     esp, 4
  92   // 15 c22c00          ret     2Ch
  93   //
  94   // So we base the structure on the bigger one:
  95   BYTE mov_eax;         // = B8
  96   ULONG service_id;
  97   USHORT xor_ecx;       // = 33 C9
  98   ULONG lea_edx;        // = 8D 54 24 04
  99   ULONG call_fs1;       // = 64 FF 15 C0
 100   USHORT call_fs2;      // = 00 00
 101   BYTE call_fs3;        // = 00
 102   BYTE add_esp1;        // = 83             or ret
 103   USHORT add_esp2;      // = C4 04          or num_params
 104   BYTE ret;             // = C2
 105   USHORT num_params;
 106 };
 107
 108 // Service code for a 32 bit process running on 64 bit Windows 8.
 109 struct Wow64EntryW8 {
 110   // 00 b825000000      mov     eax, 25h
 111   // 05 64ff15c0000000  call    dword ptr fs:[0C0h]
 112   // 0b c22c00          ret     2Ch
 113   // 0f 90              nop
 114   BYTE mov_eax;         // = B8
 115   ULONG service_id;
 116   ULONG call_fs1;       // = 64 FF 15 C0
 117   USHORT call_fs2;      // = 00 00
 118   BYTE call_fs3;        // = 00
 119   BYTE ret;             // = C2
 120   USHORT num_params;
 121   BYTE nop;
 122 };
 123
 124 // Make sure that relaxed patching works as expected.
 125 const size_t kMinServiceSize = offsetof(ServiceEntry, ret);
 126 COMPILE_ASSERT(sizeof(ServiceEntryW8) >= kMinServiceSize, wrong_service_len);
 127 COMPILE_ASSERT(sizeof(Wow64Entry) >= kMinServiceSize, wrong_service_len);
 128 COMPILE_ASSERT(sizeof(Wow64EntryW8) >= kMinServiceSize, wrong_service_len);
 129
 130 struct ServiceFullThunk {
 131   union {
 132     ServiceEntry original;
 133     ServiceEntryW8 original_w8;
 134     Wow64Entry wow_64;
 135     Wow64EntryW8 wow_64_w8;
 136   };
 137   int internal_thunk;  // Dummy member to the beginning of the internal thunk.
 138 };
 139
 140 #pragma pack(pop)
 141
 142 };  // namespace
 143
 144 namespace sandbox {
 145
 146 NTSTATUS ServiceResolverThunk::Setup(const void* target_module,
 147                                      const void* interceptor_module,
 148                                      const char* target_name,
 149                                      const char* interceptor_name,
 150                                      const void* interceptor_entry_point,
 151                                      void* thunk_storage,
 152                                      size_t storage_bytes,
 153                                      size_t* storage_used) {
 154   NTSTATUS ret = Init(target_module, interceptor_module, target_name,
 155                       interceptor_name, interceptor_entry_point,
 156                       thunk_storage, storage_bytes);
 157   if (!NT_SUCCESS(ret))
 158     return ret;
 159
 160   relative_jump_ = 0;
 161   size_t thunk_bytes = GetThunkSize();
 162   scoped_ptr<char[]> thunk_buffer(new char[thunk_bytes]);
 163   ServiceFullThunk* thunk = reinterpret_cast<ServiceFullThunk*>(
 164                                 thunk_buffer.get());
 165
 166   if (!IsFunctionAService(&thunk->original) &&
 167       (!relaxed_ || !SaveOriginalFunction(&thunk->original, thunk_storage)))
 168     return STATUS_UNSUCCESSFUL;
 169
 170   ret = PerformPatch(thunk, thunk_storage);
 171
 172   if (NULL != storage_used)
 173     *storage_used = thunk_bytes;
 174
 175   return ret;
 176 }
 177
 178 size_t ServiceResolverThunk::GetThunkSize() const {
 179   return offsetof(ServiceFullThunk, internal_thunk) + GetInternalThunkSize();
 180 }
 181
 182 bool ServiceResolverThunk::IsFunctionAService(void* local_thunk) const {
 183   ServiceEntry function_code;
 184   SIZE_T read;
 185   if (!::ReadProcessMemory(process_, target_, &function_code,
 186                            sizeof(function_code), &read))
 187     return false;
 188
 189   if (sizeof(function_code) != read)
 190     return false;
 191
 192   if (kMovEax != function_code.mov_eax ||
 193       kMovEdx != function_code.mov_edx ||
 194       (kCallPtrEdx != function_code.call_ptr_edx &&
 195        kCallEdx != function_code.call_ptr_edx) ||
 196       kRet != function_code.ret)
 197     return false;
 198
 199   // Find the system call pointer if we don't already have it.
 200   if (kCallEdx != function_code.call_ptr_edx) {
 201     DWORD ki_system_call;
 202     if (!::ReadProcessMemory(process_,
 203                              bit_cast<const void*>(function_code.stub),
 204                              &ki_system_call, sizeof(ki_system_call), &read))
 205       return false;
 206
 207     if (sizeof(ki_system_call) != read)
 208       return false;
 209
 210     HMODULE module_1, module_2;
 211     // last check, call_stub should point to a KiXXSystemCall function on ntdll
 212     if (!GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
 213                                GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
 214                            bit_cast<const wchar_t*>(ki_system_call), &module_1))
 215       return false;
 216
 217     if (NULL != ntdll_base_) {
 218       // This path is only taken when running the unit tests. We want to be
 219       // able to patch a buffer in memory, so target_ is not inside ntdll.
 220       module_2 = ntdll_base_;
 221     } else {
 222       if (!GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
 223                                  GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
 224                              reinterpret_cast<const wchar_t*>(target_),
 225                              &module_2))
 226         return false;
 227     }
 228
 229     if (module_1 != module_2)
 230       return false;
 231   }
 232
 233   // Save the verified code
 234   memcpy(local_thunk, &function_code, sizeof(function_code));
 235
 236   return true;
 237 }
 238
 239 NTSTATUS ServiceResolverThunk::PerformPatch(void* local_thunk,
 240                                             void* remote_thunk) {
 241   ServiceEntry intercepted_code;
 242   size_t bytes_to_write = sizeof(intercepted_code);
 243   ServiceFullThunk *full_local_thunk = reinterpret_cast<ServiceFullThunk*>(
 244       local_thunk);
 245   ServiceFullThunk *full_remote_thunk = reinterpret_cast<ServiceFullThunk*>(
 246       remote_thunk);
 247
 248   // patch the original code
 249   memcpy(&intercepted_code, &full_local_thunk->original,
 250          sizeof(intercepted_code));
 251   intercepted_code.mov_eax = kMovEax;
 252   intercepted_code.service_id = full_local_thunk->original.service_id;
 253   intercepted_code.mov_edx = kMovEdx;
 254   intercepted_code.stub = bit_cast<ULONG>(&full_remote_thunk->internal_thunk);
 255   intercepted_code.call_ptr_edx = kJmpEdx;
 256   bytes_to_write = kMinServiceSize;
 257
 258   if (relative_jump_) {
 259     intercepted_code.mov_eax = kJmp32;
 260     intercepted_code.service_id = relative_jump_;
 261     bytes_to_write = offsetof(ServiceEntry, mov_edx);
 262   }
 263
 264   // setup the thunk
 265   SetInternalThunk(&full_local_thunk->internal_thunk, GetInternalThunkSize(),
 266                    remote_thunk, interceptor_);
 267
 268   size_t thunk_size = GetThunkSize();
 269
 270   // copy the local thunk buffer to the child
 271   SIZE_T written;
 272   if (!::WriteProcessMemory(process_, remote_thunk, local_thunk,
 273                             thunk_size, &written))
 274     return STATUS_UNSUCCESSFUL;
 275
 276   if (thunk_size != written)
 277     return STATUS_UNSUCCESSFUL;
 278
 279   // and now change the function to intercept, on the child
 280   if (NULL != ntdll_base_) {
 281     // running a unit test
 282     if (!::WriteProcessMemory(process_, target_, &intercepted_code,
 283                               bytes_to_write, &written))
 284       return STATUS_UNSUCCESSFUL;
 285   } else {
 286     if (!WriteProtectedChildMemory(process_, target_, &intercepted_code,
 287                                    bytes_to_write))
 288       return STATUS_UNSUCCESSFUL;
 289   }
 290
 291   return STATUS_SUCCESS;
 292 }
 293
 294 bool ServiceResolverThunk::SaveOriginalFunction(void* local_thunk,
 295                                                 void* remote_thunk) {
 296   ServiceEntry function_code;
 297   SIZE_T read;
 298   if (!::ReadProcessMemory(process_, target_, &function_code,
 299                            sizeof(function_code), &read))
 300     return false;
 301
 302   if (sizeof(function_code) != read)
 303     return false;
 304
 305   if (kJmp32 == function_code.mov_eax) {
 306     // Plain old entry point patch. The relative jump address follows it.
 307     ULONG relative = function_code.service_id;
 308
 309     // First, fix our copy of their patch.
 310     relative += bit_cast<ULONG>(target_) - bit_cast<ULONG>(remote_thunk);
 311
 312     function_code.service_id = relative;
 313
 314     // And now, remember how to re-patch it.
 315     ServiceFullThunk *full_thunk =
 316         reinterpret_cast<ServiceFullThunk*>(remote_thunk);
 317
 318     const ULONG kJmp32Size = 5;
 319
 320     relative_jump_ = bit_cast<ULONG>(&full_thunk->internal_thunk) -
 321                      bit_cast<ULONG>(target_) - kJmp32Size;
 322   }
 323
 324   // Save the verified code
 325   memcpy(local_thunk, &function_code, sizeof(function_code));
 326
 327   return true;
 328 }
 329
 330 bool Wow64ResolverThunk::IsFunctionAService(void* local_thunk) const {
 331   Wow64Entry function_code;
 332   SIZE_T read;
 333   if (!::ReadProcessMemory(process_, target_, &function_code,
 334                            sizeof(function_code), &read))
 335     return false;
 336
 337   if (sizeof(function_code) != read)
 338     return false;
 339
 340   if (kMovEax != function_code.mov_eax || kXorEcx != function_code.xor_ecx ||
 341       kLeaEdx != function_code.lea_edx || kCallFs1 != function_code.call_fs1 ||
 342       kCallFs2 != function_code.call_fs2 || kCallFs3 != function_code.call_fs3)
 343     return false;
 344
 345   if ((kAddEsp1 == function_code.add_esp1 &&
 346        kAddEsp2 == function_code.add_esp2 &&
 347        kRet == function_code.ret) || kRet == function_code.add_esp1) {
 348     // Save the verified code
 349     memcpy(local_thunk, &function_code, sizeof(function_code));
 350     return true;
 351   }
 352
 353   return false;
 354 }
 355
 356 bool Wow64W8ResolverThunk::IsFunctionAService(void* local_thunk) const {
 357   Wow64EntryW8 function_code;
 358   SIZE_T read;
 359   if (!::ReadProcessMemory(process_, target_, &function_code,
 360                            sizeof(function_code), &read))
 361     return false;
 362
 363   if (sizeof(function_code) != read)
 364     return false;
 365
 366   if (kMovEax != function_code.mov_eax || kCallFs1 != function_code.call_fs1 ||
 367       kCallFs2 != function_code.call_fs2 ||
 368       kCallFs3 != function_code.call_fs3 || kRet != function_code.ret) {
 369     return false;
 370   }
 371
 372   // Save the verified code
 373   memcpy(local_thunk, &function_code, sizeof(function_code));
 374   return true;
 375 }
 376
 377 bool Win2kResolverThunk::IsFunctionAService(void* local_thunk) const {
 378   ServiceEntry function_code;
 379   SIZE_T read;
 380   if (!::ReadProcessMemory(process_, target_, &function_code,
 381                            sizeof(function_code), &read))
 382     return false;
 383
 384   if (sizeof(function_code) != read)
 385     return false;
 386
 387   if (kMovEax != function_code.mov_eax ||
 388       function_code.service_id > kMaxService)
 389     return false;
 390
 391   // Save the verified code
 392   memcpy(local_thunk, &function_code, sizeof(function_code));
 393
 394   return true;
 395 }
 396
 397 bool Win8ResolverThunk::IsFunctionAService(void* local_thunk) const {
 398   ServiceEntryW8 function_code;
 399   SIZE_T read;
 400   if (!::ReadProcessMemory(process_, target_, &function_code,
 401                            sizeof(function_code), &read))
 402     return false;
 403
 404   if (sizeof(function_code) != read)
 405     return false;
 406
 407   if (kMovEax != function_code.mov_eax || kCallEip != function_code.call_eip ||
 408       function_code.call_offset != 3 || kRet != function_code.ret_p ||
 409       kMovEdxEsp != function_code.mov_edx_esp ||
 410       kSysenter != function_code.sysenter || kRet2 != function_code.ret) {
 411     return false;
 412   }
 413
 414   // Save the verified code
 415   memcpy(local_thunk, &function_code, sizeof(function_code));
 416
 417   return true;
 418 }
 419
 420 }  // namespace sandbox