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 // Copyright (c) 2012 The Chromium Authors. All rights reserved.

 // Use of this source code is governed by a BSD-style license that can be

 // found in the LICENSE file.

 // For information about interceptions as a whole see

 // http://dev.chromium.org/developers/design-documents/sandbox .

 #include <set>

 #include "sandbox/win/src/interception.h"

 #include "base/logging.h"

 #include "base/memory/scoped_ptr.h"

 #include "base/win/pe_image.h"

 #include "base/win/windows_version.h"

 #include "sandbox/win/src/interception_internal.h"

 #include "sandbox/win/src/interceptors.h"

 #include "sandbox/win/src/sandbox.h"

 #include "sandbox/win/src/sandbox_utils.h"

 #include "sandbox/win/src/service_resolver.h"

 #include "sandbox/win/src/target_interceptions.h"

 #include "sandbox/win/src/target_process.h"

 #include "sandbox/win/src/wow64.h"

 namespace {

 const char kMapViewOfSectionName[] = "NtMapViewOfSection";

 const char kUnmapViewOfSectionName[] = "NtUnmapViewOfSection";

 // Standard allocation granularity and page size for Windows.

 const size_t kAllocGranularity = 65536;

 const size_t kPageSize = 4096;

 // Find a random offset within 64k and aligned to ceil(log2(size)).

 size_t GetGranularAlignedRandomOffset(size_t size) {

   CHECK_LE(size, kAllocGranularity);

   unsigned int offset;

   do {

     rand_s(&offset);

     offset &= (kAllocGranularity - 1);

   } while (offset > (kAllocGranularity - size));

   // Find an alignment between 64 and the page size (4096).

   size_t align_size = kPageSize;

   for (size_t new_size = align_size / 2;  new_size >= size; new_size /= 2) {

     align_size = new_size;

   }

   return offset & ~(align_size - 1);

 }

 }  // namespace

 namespace sandbox {

 SANDBOX_INTERCEPT SharedMemory* g_interceptions;

 // Table of the unpatched functions that we intercept. Mapped from the parent.

 SANDBOX_INTERCEPT OriginalFunctions g_originals = { NULL };

 // Magic constant that identifies that this function is not to be patched.

 const char kUnloadDLLDummyFunction[] = "@";

 InterceptionManager::InterceptionManager(TargetProcess* child_process,

                                          bool relaxed)

     : child_(child_process), names_used_(false), relaxed_(relaxed) {

   child_->AddRef();

 }

 InterceptionManager::~InterceptionManager() {

   child_->Release();

 }

 bool InterceptionManager::AddToPatchedFunctions(

     const wchar_t* dll_name, const char* function_name,

     InterceptionType interception_type, const void* replacement_code_address,

     InterceptorId id) {

   InterceptionData function;

   function.type = interception_type;

   function.id = id;

   function.dll = dll_name;

   function.function = function_name;

   function.interceptor_address = replacement_code_address;

   interceptions_.push_back(function);

   return true;

 }

 bool InterceptionManager::AddToPatchedFunctions(

     const wchar_t* dll_name, const char* function_name,

     InterceptionType interception_type, const char* replacement_function_name,

     InterceptorId id) {

   InterceptionData function;

   function.type = interception_type;

   function.id = id;

   function.dll = dll_name;

   function.function = function_name;

   function.interceptor = replacement_function_name;

   function.interceptor_address = NULL;

   interceptions_.push_back(function);

   names_used_ = true;

   return true;

 }

 bool InterceptionManager::AddToUnloadModules(const wchar_t* dll_name) {

   InterceptionData module_to_unload;

   module_to_unload.type = INTERCEPTION_UNLOAD_MODULE;

   module_to_unload.dll = dll_name;

   // The next two are dummy values that make the structures regular, instead

   // of having special cases. They should not be used.

   module_to_unload.function = kUnloadDLLDummyFunction;

   module_to_unload.interceptor_address = reinterpret_cast<void*>(1);

   interceptions_.push_back(module_to_unload);

   return true;

 }

 bool InterceptionManager::InitializeInterceptions() {

   if (interceptions_.empty())

     return true;  // Nothing to do here

   size_t buffer_bytes = GetBufferSize();

   scoped_ptr<char[]> local_buffer(new char[buffer_bytes]);

   if (!SetupConfigBuffer(local_buffer.get(), buffer_bytes))

     return false;

   void* remote_buffer;

   if (!CopyDataToChild(local_buffer.get(), buffer_bytes, &remote_buffer))

     return false;

   bool hot_patch_needed = (0 != buffer_bytes);

   if (!PatchNtdll(hot_patch_needed))

     return false;

   g_interceptions = reinterpret_cast<SharedMemory*>(remote_buffer);

   ResultCode rc = child_->TransferVariable("g_interceptions",

                                            &g_interceptions,

                                            sizeof(g_interceptions));

   return (SBOX_ALL_OK == rc);

 }

 size_t InterceptionManager::GetBufferSize() const {

   std::set<std::wstring> dlls;

   size_t buffer_bytes = 0;

   std::list<InterceptionData>::const_iterator it = interceptions_.begin();

   for (; it != interceptions_.end(); ++it) {

     // skip interceptions that are performed from the parent

     if (!IsInterceptionPerformedByChild(*it))

       continue;

     if (!dlls.count(it->dll)) {

       // NULL terminate the dll name on the structure

       size_t dll_name_bytes = (it->dll.size() + 1) * sizeof(wchar_t);

       // include the dll related size

       buffer_bytes += RoundUpToMultiple(offsetof(DllPatchInfo, dll_name) +

                                             dll_name_bytes, sizeof(size_t));

       dlls.insert(it->dll);

     }

     // we have to NULL terminate the strings on the structure

     size_t strings_chars = it->function.size() + it->interceptor.size() + 2;

     // a new FunctionInfo is required per function

     size_t record_bytes = offsetof(FunctionInfo, function) + strings_chars;

     record_bytes = RoundUpToMultiple(record_bytes, sizeof(size_t));

     buffer_bytes += record_bytes;

   }

   if (0 != buffer_bytes)

     // add the part of SharedMemory that we have not counted yet

     buffer_bytes += offsetof(SharedMemory, dll_list);

   return buffer_bytes;

 }

 // Basically, walk the list of interceptions moving them to the config buffer,

 // but keeping together all interceptions that belong to the same dll.

 // The config buffer is a local buffer, not the one allocated on the child.

 bool InterceptionManager::SetupConfigBuffer(void* buffer, size_t buffer_bytes) {

   if (0 == buffer_bytes)

     return true;

   DCHECK(buffer_bytes > sizeof(SharedMemory));

   SharedMemory* shared_memory = reinterpret_cast<SharedMemory*>(buffer);

   DllPatchInfo* dll_info = shared_memory->dll_list;

   int num_dlls = 0;

   shared_memory->interceptor_base = names_used_ ? child_->MainModule() : NULL;

   buffer_bytes -= offsetof(SharedMemory, dll_list);

   buffer = dll_info;

   std::list<InterceptionData>::iterator it = interceptions_.begin();

   for (; it != interceptions_.end();) {

     // skip interceptions that are performed from the parent

     if (!IsInterceptionPerformedByChild(*it)) {

       ++it;

       continue;

     }

     const std::wstring dll = it->dll;

     if (!SetupDllInfo(*it, &buffer, &buffer_bytes))

       return false;

     // walk the interceptions from this point, saving the ones that are

     // performed on this dll, and removing the entry from the list.

     // advance the iterator before removing the element from the list

     std::list<InterceptionData>::iterator rest = it;

     for (; rest != interceptions_.end();) {

       if (rest->dll == dll) {

         if (!SetupInterceptionInfo(*rest, &buffer, &buffer_bytes, dll_info))

           return false;

         if (it == rest)

           ++it;

         rest = interceptions_.erase(rest);

       } else {

         ++rest;

       }

     }

     dll_info = reinterpret_cast<DllPatchInfo*>(buffer);

     ++num_dlls;

   }

   shared_memory->num_intercepted_dlls = num_dlls;

   return true;

 }

 // Fills up just the part that depends on the dll, not the info that depends on

 // the actual interception.

 bool InterceptionManager::SetupDllInfo(const InterceptionData& data,

                                        void** buffer,

                                        size_t* buffer_bytes) const {

   DCHECK(buffer_bytes);

   DCHECK(buffer);

   DCHECK(*buffer);

   DllPatchInfo* dll_info = reinterpret_cast<DllPatchInfo*>(*buffer);

   // the strings have to be zero terminated

   size_t required = offsetof(DllPatchInfo, dll_name) +

                     (data.dll.size() + 1) * sizeof(wchar_t);

   required = RoundUpToMultiple(required, sizeof(size_t));

   if (*buffer_bytes < required)

     return false;

   *buffer_bytes -= required;

   *buffer = reinterpret_cast<char*>(*buffer) + required;

   // set up the dll info to be what we know about it at this time

   dll_info->unload_module = (data.type == INTERCEPTION_UNLOAD_MODULE);

   dll_info->record_bytes = required;

   dll_info->offset_to_functions = required;

   dll_info->num_functions = 0;

   data.dll._Copy_s(dll_info->dll_name, data.dll.size(), data.dll.size());

   dll_info->dll_name[data.dll.size()] = L'\0';

   return true;

 }

 bool InterceptionManager::SetupInterceptionInfo(const InterceptionData& data,

                                                 void** buffer,

                                                 size_t* buffer_bytes,

                                                 DllPatchInfo* dll_info) const {

   DCHECK(buffer_bytes);

   DCHECK(buffer);

   DCHECK(*buffer);

   if ((dll_info->unload_module) &&

       (data.function != kUnloadDLLDummyFunction)) {

     // Can't specify a dll for both patch and unload.

     NOTREACHED();

   }

   FunctionInfo* function = reinterpret_cast<FunctionInfo*>(*buffer);

   size_t name_bytes = data.function.size();

   size_t interceptor_bytes = data.interceptor.size();

   // the strings at the end of the structure are zero terminated

   size_t required = offsetof(FunctionInfo, function) +

                     name_bytes + interceptor_bytes + 2;

   required = RoundUpToMultiple(required, sizeof(size_t));

   if (*buffer_bytes < required)

     return false;

   // update the caller's values

   *buffer_bytes -= required;

   *buffer = reinterpret_cast<char*>(*buffer) + required;

   function->record_bytes = required;

   function->type = data.type;

   function->id = data.id;

   function->interceptor_address = data.interceptor_address;

   char* names = function->function;

   data.function._Copy_s(names, name_bytes, name_bytes);

   names += name_bytes;

   *names++ = '\0';

   // interceptor follows the function_name

   data.interceptor._Copy_s(names, interceptor_bytes, interceptor_bytes);

   names += interceptor_bytes;

   *names++ = '\0';

   // update the dll table

   dll_info->num_functions++;

   dll_info->record_bytes += required;

   return true;

 }

 bool InterceptionManager::CopyDataToChild(const void* local_buffer,

                                           size_t buffer_bytes,

                                           void** remote_buffer) const {

   DCHECK(NULL != remote_buffer);

   if (0 == buffer_bytes) {

     *remote_buffer = NULL;

     return true;

   }

   HANDLE child = child_->Process();

   // Allocate memory on the target process without specifying the address

   void* remote_data = ::VirtualAllocEx(child, NULL, buffer_bytes,

                                        MEM_COMMIT, PAGE_READWRITE);

   if (NULL == remote_data)

     return false;

   SIZE_T bytes_written;

   BOOL success = ::WriteProcessMemory(child, remote_data, local_buffer,

                                       buffer_bytes, &bytes_written);

   if (FALSE == success || bytes_written != buffer_bytes) {

     ::VirtualFreeEx(child, remote_data, 0, MEM_RELEASE);

     return false;

   }

   *remote_buffer = remote_data;

   return true;

 }

 // Only return true if the child should be able to perform this interception.

 bool InterceptionManager::IsInterceptionPerformedByChild(

     const InterceptionData& data) const {

   if (INTERCEPTION_INVALID == data.type)

     return false;

   if (INTERCEPTION_SERVICE_CALL == data.type)

     return false;

   if (data.type >= INTERCEPTION_LAST)

     return false;

   std::wstring ntdll(kNtdllName);

   if (ntdll == data.dll)

     return false;  // ntdll has to be intercepted from the parent

   return true;

 }

 bool InterceptionManager::PatchNtdll(bool hot_patch_needed) {

   // Maybe there is nothing to do

   if (!hot_patch_needed && interceptions_.empty())

     return true;

   if (hot_patch_needed) {

 #if SANDBOX_EXPORTS

     // Make sure the functions are not excluded by the linker.

 #if defined(_WIN64)

     #pragma comment(linker, "/include:TargetNtMapViewOfSection64")

     #pragma comment(linker, "/include:TargetNtUnmapViewOfSection64")

 #else

     #pragma comment(linker, "/include:_TargetNtMapViewOfSection@44")

     #pragma comment(linker, "/include:_TargetNtUnmapViewOfSection@12")

 #endif

 #endif

     ADD_NT_INTERCEPTION(NtMapViewOfSection, MAP_VIEW_OF_SECTION_ID, 44);

     ADD_NT_INTERCEPTION(NtUnmapViewOfSection, UNMAP_VIEW_OF_SECTION_ID, 12);

   }

   // Reserve a full 64k memory range in the child process.

   HANDLE child = child_->Process();

   BYTE* thunk_base = reinterpret_cast<BYTE*>(

                          ::VirtualAllocEx(child, NULL, kAllocGranularity,

                                           MEM_RESERVE, PAGE_NOACCESS));

   // Find an aligned, random location within the reserved range.

   size_t thunk_bytes = interceptions_.size() * sizeof(ThunkData) +

                        sizeof(DllInterceptionData);

   size_t thunk_offset = GetGranularAlignedRandomOffset(thunk_bytes);

   // Split the base and offset along page boundaries.

   thunk_base += thunk_offset & ~(kPageSize - 1);

   thunk_offset &= kPageSize - 1;

   // Make an aligned, padded allocation, and move the pointer to our chunk.

   size_t thunk_bytes_padded = (thunk_bytes + kPageSize - 1) & kPageSize;

   thunk_base = reinterpret_cast<BYTE*>(

                    ::VirtualAllocEx(child, thunk_base, thunk_bytes_padded,

                                     MEM_COMMIT, PAGE_EXECUTE_READWRITE));

   CHECK(thunk_base);  // If this fails we'd crash anyway on an invalid access.

   DllInterceptionData* thunks = reinterpret_cast<DllInterceptionData*>(

                                     thunk_base + thunk_offset);

   DllInterceptionData dll_data;

   dll_data.data_bytes = thunk_bytes;

   dll_data.num_thunks = 0;

   dll_data.used_bytes = offsetof(DllInterceptionData, thunks);

   // Reset all helpers for a new child.

   memset(g_originals, 0, sizeof(g_originals));

   // this should write all the individual thunks to the child's memory

   if (!PatchClientFunctions(thunks, thunk_bytes, &dll_data))

     return false;

   // and now write the first part of the table to the child's memory

   SIZE_T written;

   bool ok = FALSE != ::WriteProcessMemory(child, thunks, &dll_data,

                                           offsetof(DllInterceptionData, thunks),

                                           &written);

   if (!ok || (offsetof(DllInterceptionData, thunks) != written))

     return false;

   // Attempt to protect all the thunks, but ignore failure

   DWORD old_protection;

   ::VirtualProtectEx(child, thunks, thunk_bytes,

                      PAGE_EXECUTE_READ, &old_protection);

   ResultCode ret = child_->TransferVariable("g_originals", g_originals,

                                             sizeof(g_originals));

   return (SBOX_ALL_OK == ret);

 }

 bool InterceptionManager::PatchClientFunctions(DllInterceptionData* thunks,

                                                size_t thunk_bytes,

                                                DllInterceptionData* dll_data) {

   DCHECK(NULL != thunks);

   DCHECK(NULL != dll_data);

   HMODULE ntdll_base = ::GetModuleHandle(kNtdllName);

   if (!ntdll_base)

     return false;

   base::win::PEImage ntdll_image(ntdll_base);

   // Bypass purify's interception.

   wchar_t* loader_get = reinterpret_cast<wchar_t*>(

                             ntdll_image.GetProcAddress("LdrGetDllHandle"));

   if (loader_get) {

     if (!GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |

                                GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,

                            loader_get, &ntdll_base))

       return false;

   }

   if (base::win::GetVersion() <= base::win::VERSION_VISTA) {

     Wow64 WowHelper(child_, ntdll_base);

     if (!WowHelper.WaitForNtdll())

       return false;

   }

   char* interceptor_base = NULL;

 #if SANDBOX_EXPORTS

   interceptor_base = reinterpret_cast<char*>(child_->MainModule());

   HMODULE local_interceptor = ::LoadLibrary(child_->Name());

 #endif

   ServiceResolverThunk* thunk;

 #if defined(_WIN64)

   thunk = new ServiceResolverThunk(child_->Process(), relaxed_);

 #else

   base::win::OSInfo* os_info = base::win::OSInfo::GetInstance();

   if (os_info->wow64_status() == base::win::OSInfo::WOW64_ENABLED) {

     if (os_info->version() >= base::win::VERSION_WIN8)

       thunk = new Wow64W8ResolverThunk(child_->Process(), relaxed_);

     else

       thunk = new Wow64ResolverThunk(child_->Process(), relaxed_);

   } else if (!IsXPSP2OrLater()) {

     thunk = new Win2kResolverThunk(child_->Process(), relaxed_);

   } else if (os_info->version() >= base::win::VERSION_WIN8) {

     thunk = new Win8ResolverThunk(child_->Process(), relaxed_);

   } else {

     thunk = new ServiceResolverThunk(child_->Process(), relaxed_);

   }

 #endif

   std::list<InterceptionData>::iterator it = interceptions_.begin();

   for (; it != interceptions_.end(); ++it) {

     const std::wstring ntdll(kNtdllName);

     if (it->dll != ntdll)

       break;

     if (INTERCEPTION_SERVICE_CALL != it->type)

       break;

 #if SANDBOX_EXPORTS

     // We may be trying to patch by function name.

     if (NULL == it->interceptor_address) {

       const char* address;

       NTSTATUS ret = thunk->ResolveInterceptor(local_interceptor,

                                                it->interceptor.c_str(),

                                                reinterpret_cast<const void**>(

                                                &address));

       if (!NT_SUCCESS(ret))

         break;

       // Translate the local address to an address on the child.

       it->interceptor_address = interceptor_base + (address -

                                     reinterpret_cast<char*>(local_interceptor));

     }

 #endif

     NTSTATUS ret = thunk->Setup(ntdll_base,

                                 interceptor_base,

                                 it->function.c_str(),

                                 it->interceptor.c_str(),

                                 it->interceptor_address,

                                 &thunks->thunks[dll_data->num_thunks],

                                 thunk_bytes - dll_data->used_bytes,

                                 NULL);

     if (!NT_SUCCESS(ret))

       break;

     DCHECK(!g_originals[it->id]);

     g_originals[it->id] = &thunks->thunks[dll_data->num_thunks];

     dll_data->num_thunks++;

     dll_data->used_bytes += sizeof(ThunkData);

   }

   delete(thunk);

 #if SANDBOX_EXPORTS

   if (NULL != local_interceptor)

     ::FreeLibrary(local_interceptor);

 #endif

   if (it != interceptions_.end())

     return false;

   return true;

 }

 }  // namespace sandbox