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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.
#include "sandbox/win/src/target_services.h"
#include <new>
#include <process.h>
#include "base/basictypes.h"
#include "base/win/windows_version.h"
#include "sandbox/win/src/crosscall_client.h"
#include "sandbox/win/src/handle_closer_agent.h"
#include "sandbox/win/src/handle_interception.h"
#include "sandbox/win/src/ipc_tags.h"
#include "sandbox/win/src/process_mitigations.h"
#include "sandbox/win/src/restricted_token_utils.h"
#include "sandbox/win/src/sandbox.h"
#include "sandbox/win/src/sandbox_types.h"
#include "sandbox/win/src/sharedmem_ipc_client.h"
#include "sandbox/win/src/sandbox_nt_util.h"
namespace {
// Flushing a cached key is triggered by just opening the key and closing the
// resulting handle. RegDisablePredefinedCache() is the documented way to flush
// HKCU so do not use it with this function.
bool FlushRegKey(HKEY root) {
HKEY key;
if (ERROR_SUCCESS == ::RegOpenKeyExW(root, NULL, 0, MAXIMUM_ALLOWED, &key)) {
if (ERROR_SUCCESS != ::RegCloseKey(key))
return false;
}
return true;
}
// This function forces advapi32.dll to release some internally cached handles
// that were made during calls to RegOpenkey and RegOpenKeyEx if it is called
// with a more restrictive token. Returns true if the flushing is succesful
// although this behavior is undocumented and there is no guarantee that in
// fact this will happen in future versions of windows.
bool FlushCachedRegHandles() {
return (FlushRegKey(HKEY_LOCAL_MACHINE) &&
FlushRegKey(HKEY_CLASSES_ROOT) &&
FlushRegKey(HKEY_USERS));
}
// Checks if we have handle entries pending and runs the closer.
bool CloseOpenHandles() {
if (sandbox::HandleCloserAgent::NeedsHandlesClosed()) {
sandbox::HandleCloserAgent handle_closer;
handle_closer.InitializeHandlesToClose();
if (!handle_closer.CloseHandles())
return false;
}
return true;
}
// Used as storage for g_target_services, because other allocation facilities
// are not available early. We can't use a regular function static because on
// VS2015, because the CRT tries to acquire a lock to guard initialization, but
// this code runs before the CRT is initialized.
char g_target_services_memory[sizeof(sandbox::TargetServicesBase)];
sandbox::TargetServicesBase* g_target_services = nullptr;
} // namespace
namespace sandbox {
SANDBOX_INTERCEPT IntegrityLevel g_shared_delayed_integrity_level =
INTEGRITY_LEVEL_LAST;
SANDBOX_INTERCEPT MitigationFlags g_shared_delayed_mitigations = 0;
TargetServicesBase::TargetServicesBase() {
}
ResultCode TargetServicesBase::Init() {
process_state_.SetInitCalled();
return SBOX_ALL_OK;
}
// Failure here is a breach of security so the process is terminated.
void TargetServicesBase::LowerToken() {
if (ERROR_SUCCESS !=
SetProcessIntegrityLevel(g_shared_delayed_integrity_level))
::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_INTEGRITY);
process_state_.SetRevertedToSelf();
// If the client code as called RegOpenKey, advapi32.dll has cached some
// handles. The following code gets rid of them.
if (!::RevertToSelf())
::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_DROPTOKEN);
if (!FlushCachedRegHandles())
::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_FLUSHANDLES);
if (ERROR_SUCCESS != ::RegDisablePredefinedCache())
::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_CACHEDISABLE);
if (!CloseOpenHandles())
::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_CLOSEHANDLES);
// Enabling mitigations must happen last otherwise handle closing breaks
if (g_shared_delayed_mitigations &&
!ApplyProcessMitigationsToCurrentProcess(g_shared_delayed_mitigations))
::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_MITIGATION);
}
ProcessState* TargetServicesBase::GetState() {
return &process_state_;
}
TargetServicesBase* TargetServicesBase::GetInstance() {
// Leak on purpose TargetServicesBase.
if (!g_target_services)
g_target_services = new (g_target_services_memory) TargetServicesBase;
return g_target_services;
}
// The broker services a 'test' IPC service with the IPC_PING_TAG tag.
bool TargetServicesBase::TestIPCPing(int version) {
void* memory = GetGlobalIPCMemory();
if (NULL == memory) {
return false;
}
SharedMemIPCClient ipc(memory);
CrossCallReturn answer = {0};
if (1 == version) {
uint32 tick1 = ::GetTickCount();
uint32 cookie = 717115;
ResultCode code = CrossCall(ipc, IPC_PING1_TAG, cookie, &answer);
if (SBOX_ALL_OK != code) {
return false;
}
// We should get two extended returns values from the IPC, one is the
// tick count on the broker and the other is the cookie times two.
if ((answer.extended_count != 2)) {
return false;
}
// We test the first extended answer to be within the bounds of the tick
// count only if there was no tick count wraparound.
uint32 tick2 = ::GetTickCount();
if (tick2 >= tick1) {
if ((answer.extended[0].unsigned_int < tick1) ||
(answer.extended[0].unsigned_int > tick2)) {
return false;
}
}
if (answer.extended[1].unsigned_int != cookie * 2) {
return false;
}
} else if (2 == version) {
uint32 cookie = 717111;
InOutCountedBuffer counted_buffer(&cookie, sizeof(cookie));
ResultCode code = CrossCall(ipc, IPC_PING2_TAG, counted_buffer, &answer);
if (SBOX_ALL_OK != code) {
return false;
}
if (cookie != 717111 * 3) {
return false;
}
} else {
return false;
}
return true;
}
ProcessState::ProcessState() : process_state_(0) {
}
bool ProcessState::IsKernel32Loaded() const {
return process_state_ != 0;
}
bool ProcessState::InitCalled() const {
return process_state_ > 1;
}
bool ProcessState::RevertedToSelf() const {
return process_state_ > 2;
}
void ProcessState::SetKernel32Loaded() {
if (!process_state_)
process_state_ = 1;
}
void ProcessState::SetInitCalled() {
if (process_state_ < 2)
process_state_ = 2;
}
void ProcessState::SetRevertedToSelf() {
if (process_state_ < 3)
process_state_ = 3;
}
ResultCode TargetServicesBase::DuplicateHandle(HANDLE source_handle,
DWORD target_process_id,
HANDLE* target_handle,
DWORD desired_access,
DWORD options) {
return sandbox::DuplicateHandleProxy(source_handle, target_process_id,
target_handle, desired_access, options);
}
} // namespace sandbox
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