The Tor Browser: comparison security/sandbox/win/src/interception.cc

--1:000000000000
+:7446bf816237
+// 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

The Tor Browser / file comparison

comparison: security/sandbox/win/src/interception.cc

security/sandbox/win/src/interception.cc