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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/process_mitigations.h"
#include <algorithm>
#include "base/win/windows_version.h"
#include "sandbox/win/src/nt_internals.h"
#include "sandbox/win/src/sandbox_utils.h"
#include "sandbox/win/src/win_utils.h"
namespace {
// Functions for enabling policies.
typedef BOOL (WINAPI *SetProcessDEPPolicyFunction)(DWORD dwFlags);
typedef BOOL (WINAPI *SetProcessMitigationPolicyFunction)(
PROCESS_MITIGATION_POLICY mitigation_policy,
PVOID buffer,
SIZE_T length);
typedef BOOL (WINAPI *SetDefaultDllDirectoriesFunction)(
DWORD DirectoryFlags);
} // namespace
namespace sandbox {
bool ApplyProcessMitigationsToCurrentProcess(MitigationFlags flags) {
if (!CanSetProcessMitigationsPostStartup(flags))
return false;
// We can't apply anything before Win XP, so just return cleanly.
if (!IsXPSP2OrLater())
return true;
base::win::Version version = base::win::GetVersion();
HMODULE module = ::GetModuleHandleA("kernel32.dll");
if (version >= base::win::VERSION_VISTA &&
(flags & MITIGATION_DLL_SEARCH_ORDER)) {
SetDefaultDllDirectoriesFunction set_default_dll_directories =
reinterpret_cast<SetDefaultDllDirectoriesFunction>(
::GetProcAddress(module, "SetDefaultDllDirectories"));
// Check for SetDefaultDllDirectories since it requires KB2533623.
if (set_default_dll_directories) {
if (!set_default_dll_directories(LOAD_LIBRARY_SEARCH_DEFAULT_DIRS) &&
ERROR_ACCESS_DENIED != ::GetLastError()) {
return false;
}
}
}
// Set the heap to terminate on corruption
if (version >= base::win::VERSION_VISTA &&
(flags & MITIGATION_HEAP_TERMINATE)) {
if (!::HeapSetInformation(NULL, HeapEnableTerminationOnCorruption,
NULL, 0) &&
ERROR_ACCESS_DENIED != ::GetLastError()) {
return false;
}
}
#if !defined(_WIN64) // DEP is always enabled on 64-bit.
if (flags & MITIGATION_DEP) {
DWORD dep_flags = PROCESS_DEP_ENABLE;
// DEP support is quirky on XP, so don't force a failure in that case.
const bool return_on_fail = version >= base::win::VERSION_VISTA;
if (flags & MITIGATION_DEP_NO_ATL_THUNK)
dep_flags |= PROCESS_DEP_DISABLE_ATL_THUNK_EMULATION;
SetProcessDEPPolicyFunction set_process_dep_policy =
reinterpret_cast<SetProcessDEPPolicyFunction>(
::GetProcAddress(module, "SetProcessDEPPolicy"));
if (set_process_dep_policy) {
if (!set_process_dep_policy(dep_flags) &&
ERROR_ACCESS_DENIED != ::GetLastError() && return_on_fail) {
return false;
}
} else {
// We're on XP sp2, so use the less standard approach.
// For reference: http://www.uninformed.org/?v=2&a=4
const int MEM_EXECUTE_OPTION_ENABLE = 1;
const int MEM_EXECUTE_OPTION_DISABLE = 2;
const int MEM_EXECUTE_OPTION_ATL7_THUNK_EMULATION = 4;
const int MEM_EXECUTE_OPTION_PERMANENT = 8;
NtSetInformationProcessFunction set_information_process = NULL;
ResolveNTFunctionPtr("NtSetInformationProcess",
&set_information_process);
if (!set_information_process)
return false;
ULONG dep = MEM_EXECUTE_OPTION_DISABLE | MEM_EXECUTE_OPTION_PERMANENT;
if (!(dep_flags & PROCESS_DEP_DISABLE_ATL_THUNK_EMULATION))
dep |= MEM_EXECUTE_OPTION_ATL7_THUNK_EMULATION;
if (!SUCCEEDED(set_information_process(GetCurrentProcess(),
ProcessExecuteFlags,
&dep, sizeof(dep))) &&
ERROR_ACCESS_DENIED != ::GetLastError() && return_on_fail) {
return false;
}
}
}
#endif
// This is all we can do in Win7 and below.
if (version < base::win::VERSION_WIN8)
return true;
SetProcessMitigationPolicyFunction set_process_mitigation_policy =
reinterpret_cast<SetProcessMitigationPolicyFunction>(
::GetProcAddress(module, "SetProcessMitigationPolicy"));
if (!set_process_mitigation_policy)
return false;
// Enable ASLR policies.
if (flags & MITIGATION_RELOCATE_IMAGE) {
PROCESS_MITIGATION_ASLR_POLICY policy = { 0 };
policy.EnableForceRelocateImages = true;
policy.DisallowStrippedImages = (flags &
MITIGATION_RELOCATE_IMAGE_REQUIRED) ==
MITIGATION_RELOCATE_IMAGE_REQUIRED;
if (!set_process_mitigation_policy(ProcessASLRPolicy, &policy,
sizeof(policy)) &&
ERROR_ACCESS_DENIED != ::GetLastError()) {
return false;
}
}
// Enable strict handle policies.
if (flags & MITIGATION_STRICT_HANDLE_CHECKS) {
PROCESS_MITIGATION_STRICT_HANDLE_CHECK_POLICY policy = { 0 };
policy.HandleExceptionsPermanentlyEnabled =
policy.RaiseExceptionOnInvalidHandleReference = true;
if (!set_process_mitigation_policy(ProcessStrictHandleCheckPolicy, &policy,
sizeof(policy)) &&
ERROR_ACCESS_DENIED != ::GetLastError()) {
return false;
}
}
// Enable system call policies.
if (flags & MITIGATION_WIN32K_DISABLE) {
PROCESS_MITIGATION_SYSTEM_CALL_DISABLE_POLICY policy = { 0 };
policy.DisallowWin32kSystemCalls = true;
if (!set_process_mitigation_policy(ProcessSystemCallDisablePolicy, &policy,
sizeof(policy)) &&
ERROR_ACCESS_DENIED != ::GetLastError()) {
return false;
}
}
// Enable system call policies.
if (flags & MITIGATION_EXTENSION_DLL_DISABLE) {
PROCESS_MITIGATION_EXTENSION_POINT_DISABLE_POLICY policy = { 0 };
policy.DisableExtensionPoints = true;
if (!set_process_mitigation_policy(ProcessExtensionPointDisablePolicy,
&policy, sizeof(policy)) &&
ERROR_ACCESS_DENIED != ::GetLastError()) {
return false;
}
}
return true;
}
void ConvertProcessMitigationsToPolicy(MitigationFlags flags,
DWORD64* policy_flags, size_t* size) {
base::win::Version version = base::win::GetVersion();
*policy_flags = 0;
#if defined(_WIN64)
*size = sizeof(*policy_flags);
#elif defined(_M_IX86)
// A 64-bit flags attribute is illegal on 32-bit Win 7 and below.
if (version < base::win::VERSION_WIN8)
*size = sizeof(DWORD);
else
*size = sizeof(*policy_flags);
#else
#error This platform is not supported.
#endif
// Nothing for Win XP or Vista.
if (version <= base::win::VERSION_VISTA)
return;
// DEP and SEHOP are not valid for 64-bit Windows
#if !defined(_WIN64)
if (flags & MITIGATION_DEP) {
*policy_flags |= PROCESS_CREATION_MITIGATION_POLICY_DEP_ENABLE;
if (!(flags & MITIGATION_DEP_NO_ATL_THUNK))
*policy_flags |= PROCESS_CREATION_MITIGATION_POLICY_DEP_ATL_THUNK_ENABLE;
}
if (flags & MITIGATION_SEHOP)
*policy_flags |= PROCESS_CREATION_MITIGATION_POLICY_SEHOP_ENABLE;
#endif
// Win 7
if (version < base::win::VERSION_WIN8)
return;
if (flags & MITIGATION_RELOCATE_IMAGE) {
*policy_flags |=
PROCESS_CREATION_MITIGATION_POLICY_FORCE_RELOCATE_IMAGES_ALWAYS_ON;
if (flags & MITIGATION_RELOCATE_IMAGE_REQUIRED) {
*policy_flags |=
PROCESS_CREATION_MITIGATION_POLICY_FORCE_RELOCATE_IMAGES_ALWAYS_ON_REQ_RELOCS;
}
}
if (flags & MITIGATION_HEAP_TERMINATE) {
*policy_flags |=
PROCESS_CREATION_MITIGATION_POLICY_HEAP_TERMINATE_ALWAYS_ON;
}
if (flags & MITIGATION_BOTTOM_UP_ASLR) {
*policy_flags |=
PROCESS_CREATION_MITIGATION_POLICY_BOTTOM_UP_ASLR_ALWAYS_ON;
}
if (flags & MITIGATION_HIGH_ENTROPY_ASLR) {
*policy_flags |=
PROCESS_CREATION_MITIGATION_POLICY_HIGH_ENTROPY_ASLR_ALWAYS_ON;
}
if (flags & MITIGATION_STRICT_HANDLE_CHECKS) {
*policy_flags |=
PROCESS_CREATION_MITIGATION_POLICY_STRICT_HANDLE_CHECKS_ALWAYS_ON;
}
if (flags & MITIGATION_WIN32K_DISABLE) {
*policy_flags |=
PROCESS_CREATION_MITIGATION_POLICY_WIN32K_SYSTEM_CALL_DISABLE_ALWAYS_ON;
}
if (flags & MITIGATION_EXTENSION_DLL_DISABLE) {
*policy_flags |=
PROCESS_CREATION_MITIGATION_POLICY_EXTENSION_POINT_DISABLE_ALWAYS_ON;
}
}
MitigationFlags FilterPostStartupProcessMitigations(MitigationFlags flags) {
// Anything prior to XP SP2.
if (!IsXPSP2OrLater())
return 0;
base::win::Version version = base::win::GetVersion();
// Windows XP SP2+.
if (version < base::win::VERSION_VISTA) {
return flags & (MITIGATION_DEP |
MITIGATION_DEP_NO_ATL_THUNK);
}
// Windows Vista
if (version < base::win::VERSION_WIN7) {
return flags & (MITIGATION_DEP |
MITIGATION_DEP_NO_ATL_THUNK |
MITIGATION_BOTTOM_UP_ASLR |
MITIGATION_DLL_SEARCH_ORDER |
MITIGATION_HEAP_TERMINATE);
}
// Windows 7.
if (version < base::win::VERSION_WIN8) {
return flags & (MITIGATION_BOTTOM_UP_ASLR |
MITIGATION_DLL_SEARCH_ORDER |
MITIGATION_HEAP_TERMINATE);
}
// Windows 8 and above.
return flags & (MITIGATION_BOTTOM_UP_ASLR |
MITIGATION_DLL_SEARCH_ORDER);
}
bool ApplyProcessMitigationsToSuspendedProcess(HANDLE process,
MitigationFlags flags) {
// This is a hack to fake a weak bottom-up ASLR on 32-bit Windows.
#if !defined(_WIN64)
if (flags & MITIGATION_BOTTOM_UP_ASLR) {
unsigned int limit;
rand_s(&limit);
char* ptr = 0;
const size_t kMask64k = 0xFFFF;
// Random range (512k-16.5mb) in 64k steps.
const char* end = ptr + ((((limit % 16384) + 512) * 1024) & ~kMask64k);
while (ptr < end) {
MEMORY_BASIC_INFORMATION memory_info;
if (!::VirtualQueryEx(process, ptr, &memory_info, sizeof(memory_info)))
break;
size_t size = std::min((memory_info.RegionSize + kMask64k) & ~kMask64k,
static_cast<SIZE_T>(end - ptr));
if (ptr && memory_info.State == MEM_FREE)
::VirtualAllocEx(process, ptr, size, MEM_RESERVE, PAGE_NOACCESS);
ptr += size;
}
}
#endif
return true;
}
bool CanSetProcessMitigationsPostStartup(MitigationFlags flags) {
// All of these mitigations can be enabled after startup.
return !(flags & ~(MITIGATION_HEAP_TERMINATE |
MITIGATION_DEP |
MITIGATION_DEP_NO_ATL_THUNK |
MITIGATION_RELOCATE_IMAGE |
MITIGATION_RELOCATE_IMAGE_REQUIRED |
MITIGATION_BOTTOM_UP_ASLR |
MITIGATION_STRICT_HANDLE_CHECKS |
MITIGATION_WIN32K_DISABLE |
MITIGATION_EXTENSION_DLL_DISABLE |
MITIGATION_DLL_SEARCH_ORDER));
}
bool CanSetProcessMitigationsPreStartup(MitigationFlags flags) {
// These mitigations cannot be enabled prior to startup.
return !(flags & (MITIGATION_STRICT_HANDLE_CHECKS |
MITIGATION_WIN32K_DISABLE |
MITIGATION_DLL_SEARCH_ORDER));
}
} // namespace sandbox
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