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 static_assert(sizeof(ServiceEntryW8) >= kMinServiceSize,
 127               "wrong service length");
 128 static_assert(sizeof(Wow64Entry) >= kMinServiceSize, "wrong service length");
 129 static_assert(sizeof(Wow64EntryW8) >= kMinServiceSize, "wrong service length");
 130
 131 struct ServiceFullThunk {
 132   union {
 133     ServiceEntry original;
 134     ServiceEntryW8 original_w8;
 135     Wow64Entry wow_64;
 136     Wow64EntryW8 wow_64_w8;
 137   };
 138   int internal_thunk;  // Dummy member to the beginning of the internal thunk.
 139 };
 140
 141 #pragma pack(pop)
 142
 143 };  // namespace
 144
 145 namespace sandbox {
 146
 147 NTSTATUS ServiceResolverThunk::Setup(const void* target_module,
 148                                      const void* interceptor_module,
 149                                      const char* target_name,
 150                                      const char* interceptor_name,
 151                                      const void* interceptor_entry_point,
 152                                      void* thunk_storage,
 153                                      size_t storage_bytes,
 154                                      size_t* storage_used) {
 155   NTSTATUS ret = Init(target_module, interceptor_module, target_name,
 156                       interceptor_name, interceptor_entry_point,
 157                       thunk_storage, storage_bytes);
 158   if (!NT_SUCCESS(ret))
 159     return ret;
 160
 161   relative_jump_ = 0;
 162   size_t thunk_bytes = GetThunkSize();
 163   scoped_ptr<char[]> thunk_buffer(new char[thunk_bytes]);
 164   ServiceFullThunk* thunk = reinterpret_cast<ServiceFullThunk*>(
 165                                 thunk_buffer.get());
 166
 167   if (!IsFunctionAService(&thunk->original) &&
 168       (!relaxed_ || !SaveOriginalFunction(&thunk->original, thunk_storage)))
 169     return STATUS_UNSUCCESSFUL;
 170
 171   ret = PerformPatch(thunk, thunk_storage);
 172
 173   if (NULL != storage_used)
 174     *storage_used = thunk_bytes;
 175
 176   return ret;
 177 }
 178
 179 size_t ServiceResolverThunk::GetThunkSize() const {
 180   return offsetof(ServiceFullThunk, internal_thunk) + GetInternalThunkSize();
 181 }
 182
 183 NTSTATUS ServiceResolverThunk::CopyThunk(const void* target_module,
 184                                          const char* target_name,
 185                                          BYTE* thunk_storage,
 186                                          size_t storage_bytes,
 187                                          size_t* storage_used) {
 188   NTSTATUS ret = ResolveTarget(target_module, target_name, &target_);
 189   if (!NT_SUCCESS(ret))
 190     return ret;
 191
 192   size_t thunk_bytes = GetThunkSize();
 193   if (storage_bytes < thunk_bytes)
 194     return STATUS_UNSUCCESSFUL;
 195
 196   ServiceFullThunk* thunk = reinterpret_cast<ServiceFullThunk*>(thunk_storage);
 197
 198   if (!IsFunctionAService(&thunk->original) &&
 199       (!relaxed_ || !SaveOriginalFunction(&thunk->original, thunk_storage))) {
 200     return STATUS_UNSUCCESSFUL;
 201   }
 202
 203   if (NULL != storage_used)
 204     *storage_used = thunk_bytes;
 205
 206   return ret;
 207 }
 208
 209 bool ServiceResolverThunk::IsFunctionAService(void* local_thunk) const {
 210   ServiceEntry function_code;
 211   SIZE_T read;
 212   if (!::ReadProcessMemory(process_, target_, &function_code,
 213                            sizeof(function_code), &read))
 214     return false;
 215
 216   if (sizeof(function_code) != read)
 217     return false;
 218
 219   if (kMovEax != function_code.mov_eax ||
 220       kMovEdx != function_code.mov_edx ||
 221       (kCallPtrEdx != function_code.call_ptr_edx &&
 222        kCallEdx != function_code.call_ptr_edx) ||
 223       kRet != function_code.ret)
 224     return false;
 225
 226   // Find the system call pointer if we don't already have it.
 227   if (kCallEdx != function_code.call_ptr_edx) {
 228     DWORD ki_system_call;
 229     if (!::ReadProcessMemory(process_,
 230                              bit_cast<const void*>(function_code.stub),
 231                              &ki_system_call, sizeof(ki_system_call), &read))
 232       return false;
 233
 234     if (sizeof(ki_system_call) != read)
 235       return false;
 236
 237     HMODULE module_1, module_2;
 238     // last check, call_stub should point to a KiXXSystemCall function on ntdll
 239     if (!GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
 240                                GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
 241                            bit_cast<const wchar_t*>(ki_system_call), &module_1))
 242       return false;
 243
 244     if (NULL != ntdll_base_) {
 245       // This path is only taken when running the unit tests. We want to be
 246       // able to patch a buffer in memory, so target_ is not inside ntdll.
 247       module_2 = ntdll_base_;
 248     } else {
 249       if (!GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
 250                                  GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
 251                              reinterpret_cast<const wchar_t*>(target_),
 252                              &module_2))
 253         return false;
 254     }
 255
 256     if (module_1 != module_2)
 257       return false;
 258   }
 259
 260   // Save the verified code
 261   memcpy(local_thunk, &function_code, sizeof(function_code));
 262
 263   return true;
 264 }
 265
 266 NTSTATUS ServiceResolverThunk::PerformPatch(void* local_thunk,
 267                                             void* remote_thunk) {
 268   ServiceEntry intercepted_code;
 269   size_t bytes_to_write = sizeof(intercepted_code);
 270   ServiceFullThunk *full_local_thunk = reinterpret_cast<ServiceFullThunk*>(
 271       local_thunk);
 272   ServiceFullThunk *full_remote_thunk = reinterpret_cast<ServiceFullThunk*>(
 273       remote_thunk);
 274
 275   // patch the original code
 276   memcpy(&intercepted_code, &full_local_thunk->original,
 277          sizeof(intercepted_code));
 278   intercepted_code.mov_eax = kMovEax;
 279   intercepted_code.service_id = full_local_thunk->original.service_id;
 280   intercepted_code.mov_edx = kMovEdx;
 281   intercepted_code.stub = bit_cast<ULONG>(&full_remote_thunk->internal_thunk);
 282   intercepted_code.call_ptr_edx = kJmpEdx;
 283   bytes_to_write = kMinServiceSize;
 284
 285   if (relative_jump_) {
 286     intercepted_code.mov_eax = kJmp32;
 287     intercepted_code.service_id = relative_jump_;
 288     bytes_to_write = offsetof(ServiceEntry, mov_edx);
 289   }
 290
 291   // setup the thunk
 292   SetInternalThunk(&full_local_thunk->internal_thunk, GetInternalThunkSize(),
 293                    remote_thunk, interceptor_);
 294
 295   size_t thunk_size = GetThunkSize();
 296
 297   // copy the local thunk buffer to the child
 298   SIZE_T written;
 299   if (!::WriteProcessMemory(process_, remote_thunk, local_thunk,
 300                             thunk_size, &written))
 301     return STATUS_UNSUCCESSFUL;
 302
 303   if (thunk_size != written)
 304     return STATUS_UNSUCCESSFUL;
 305
 306   // and now change the function to intercept, on the child
 307   if (NULL != ntdll_base_) {
 308     // running a unit test
 309     if (!::WriteProcessMemory(process_, target_, &intercepted_code,
 310                               bytes_to_write, &written))
 311       return STATUS_UNSUCCESSFUL;
 312   } else {
 313     if (!WriteProtectedChildMemory(process_, target_, &intercepted_code,
 314                                    bytes_to_write))
 315       return STATUS_UNSUCCESSFUL;
 316   }
 317
 318   return STATUS_SUCCESS;
 319 }
 320
 321 bool ServiceResolverThunk::SaveOriginalFunction(void* local_thunk,
 322                                                 void* remote_thunk) {
 323   ServiceEntry function_code;
 324   SIZE_T read;
 325   if (!::ReadProcessMemory(process_, target_, &function_code,
 326                            sizeof(function_code), &read))
 327     return false;
 328
 329   if (sizeof(function_code) != read)
 330     return false;
 331
 332   if (kJmp32 == function_code.mov_eax) {
 333     // Plain old entry point patch. The relative jump address follows it.
 334     ULONG relative = function_code.service_id;
 335
 336     // First, fix our copy of their patch.
 337     relative += bit_cast<ULONG>(target_) - bit_cast<ULONG>(remote_thunk);
 338
 339     function_code.service_id = relative;
 340
 341     // And now, remember how to re-patch it.
 342     ServiceFullThunk *full_thunk =
 343         reinterpret_cast<ServiceFullThunk*>(remote_thunk);
 344
 345     const ULONG kJmp32Size = 5;
 346
 347     relative_jump_ = bit_cast<ULONG>(&full_thunk->internal_thunk) -
 348                      bit_cast<ULONG>(target_) - kJmp32Size;
 349   }
 350
 351   // Save the verified code
 352   memcpy(local_thunk, &function_code, sizeof(function_code));
 353
 354   return true;
 355 }
 356
 357 bool Wow64ResolverThunk::IsFunctionAService(void* local_thunk) const {
 358   Wow64Entry function_code;
 359   SIZE_T read;
 360   if (!::ReadProcessMemory(process_, target_, &function_code,
 361                            sizeof(function_code), &read))
 362     return false;
 363
 364   if (sizeof(function_code) != read)
 365     return false;
 366
 367   if (kMovEax != function_code.mov_eax || kXorEcx != function_code.xor_ecx ||
 368       kLeaEdx != function_code.lea_edx || kCallFs1 != function_code.call_fs1 ||
 369       kCallFs2 != function_code.call_fs2 || kCallFs3 != function_code.call_fs3)
 370     return false;
 371
 372   if ((kAddEsp1 == function_code.add_esp1 &&
 373        kAddEsp2 == function_code.add_esp2 &&
 374        kRet == function_code.ret) || kRet == function_code.add_esp1) {
 375     // Save the verified code
 376     memcpy(local_thunk, &function_code, sizeof(function_code));
 377     return true;
 378   }
 379
 380   return false;
 381 }
 382
 383 bool Wow64W8ResolverThunk::IsFunctionAService(void* local_thunk) const {
 384   Wow64EntryW8 function_code;
 385   SIZE_T read;
 386   if (!::ReadProcessMemory(process_, target_, &function_code,
 387                            sizeof(function_code), &read))
 388     return false;
 389
 390   if (sizeof(function_code) != read)
 391     return false;
 392
 393   if (kMovEax != function_code.mov_eax || kCallFs1 != function_code.call_fs1 ||
 394       kCallFs2 != function_code.call_fs2 ||
 395       kCallFs3 != function_code.call_fs3 || kRet != function_code.ret) {
 396     return false;
 397   }
 398
 399   // Save the verified code
 400   memcpy(local_thunk, &function_code, sizeof(function_code));
 401   return true;
 402 }
 403
 404 bool Win8ResolverThunk::IsFunctionAService(void* local_thunk) const {
 405   ServiceEntryW8 function_code;
 406   SIZE_T read;
 407   if (!::ReadProcessMemory(process_, target_, &function_code,
 408                            sizeof(function_code), &read))
 409     return false;
 410
 411   if (sizeof(function_code) != read)
 412     return false;
 413
 414   if (kMovEax != function_code.mov_eax || kCallEip != function_code.call_eip ||
 415       function_code.call_offset != 3 || kRet != function_code.ret_p ||
 416       kMovEdxEsp != function_code.mov_edx_esp ||
 417       kSysenter != function_code.sysenter || kRet2 != function_code.ret) {
 418     return false;
 419   }
 420
 421   // Save the verified code
 422   memcpy(local_thunk, &function_code, sizeof(function_code));
 423
 424   return true;
 425 }
 426
 427 }  // namespace sandbox