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// Copyright (c) 2006-2010 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/src/interception.h"
#include "base/logging.h"
#include "base/scoped_ptr.h"
#include "base/win/pe_image.h"
#include "sandbox/src/interception_internal.h"
#include "sandbox/src/interceptors.h"
#include "sandbox/src/sandbox.h"
#include "sandbox/src/sandbox_utils.h"
#include "sandbox/src/service_resolver.h"
#include "sandbox/src/target_interceptions.h"
#include "sandbox/src/target_process.h"
#include "sandbox/src/wow64.h"
namespace {
const char kMapViewOfSectionName[] = "NtMapViewOfSection";
const char kUnmapViewOfSectionName[] = "NtUnmapViewOfSection";
} // 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_array<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);
}
size_t thunk_bytes = interceptions_.size() * sizeof(ThunkData) +
sizeof(DllInterceptionData);
// Allocate memory on the child, without specifying the desired address
HANDLE child = child_->Process();
DllInterceptionData* thunks = reinterpret_cast<DllInterceptionData*>(
::VirtualAllocEx(child, NULL, thunk_bytes,
MEM_COMMIT,
PAGE_EXECUTE_READWRITE));
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 ? true : false;
}
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 (!GetModuleHandleHelper(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
loader_get, &ntdll_base))
return false;
}
Wow64 WowHelper(child_, ntdll_base);
if (!WowHelper.WaitForNtdll(INFINITE))
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 (WowHelper.IsWow64())
thunk = new Wow64ResolverThunk(child_->Process(), relaxed_);
else if (!IsXPSP2OrLater())
thunk = new Win2kResolverThunk(child_->Process(), relaxed_);
else
thunk = new ServiceResolverThunk(child_->Process(), relaxed_);
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
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