sandbox/win/src/process_mitigations.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "sandbox/win/src/process_mitigations.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/win/windows_version.h"
  10 #include "sandbox/win/src/nt_internals.h"
  11 #include "sandbox/win/src/restricted_token_utils.h"
  12 #include "sandbox/win/src/win_utils.h"
  13
  14 namespace {
  15
  16 // Functions for enabling policies.
  17 typedef BOOL (WINAPI *SetProcessDEPPolicyFunction)(DWORD dwFlags);
  18
  19 typedef BOOL (WINAPI *SetProcessMitigationPolicyFunction)(
  20     PROCESS_MITIGATION_POLICY mitigation_policy,
  21     PVOID buffer,
  22     SIZE_T length);
  23
  24 typedef BOOL (WINAPI *SetDefaultDllDirectoriesFunction)(
  25     DWORD DirectoryFlags);
  26
  27 }  // namespace
  28
  29 namespace sandbox {
  30
  31 bool ApplyProcessMitigationsToCurrentProcess(MitigationFlags flags) {
  32   if (!CanSetProcessMitigationsPostStartup(flags))
  33     return false;
  34
  35   base::win::Version version = base::win::GetVersion();
  36   HMODULE module = ::GetModuleHandleA("kernel32.dll");
  37
  38   if (version >= base::win::VERSION_VISTA &&
  39       (flags & MITIGATION_DLL_SEARCH_ORDER)) {
  40     SetDefaultDllDirectoriesFunction set_default_dll_directories =
  41         reinterpret_cast<SetDefaultDllDirectoriesFunction>(
  42             ::GetProcAddress(module, "SetDefaultDllDirectories"));
  43
  44     // Check for SetDefaultDllDirectories since it requires KB2533623.
  45     if (set_default_dll_directories) {
  46       if (!set_default_dll_directories(LOAD_LIBRARY_SEARCH_DEFAULT_DIRS) &&
  47           ERROR_ACCESS_DENIED != ::GetLastError()) {
  48         return false;
  49       }
  50     }
  51   }
  52
  53   // Set the heap to terminate on corruption
  54   if (version >= base::win::VERSION_VISTA &&
  55       (flags & MITIGATION_HEAP_TERMINATE)) {
  56     if (!::HeapSetInformation(NULL, HeapEnableTerminationOnCorruption,
  57                               NULL, 0) &&
  58         ERROR_ACCESS_DENIED != ::GetLastError()) {
  59       return false;
  60     }
  61   }
  62
  63   if (version >= base::win::VERSION_WIN7 &&
  64       (flags & MITIGATION_HARDEN_TOKEN_IL_POLICY)) {
  65       DWORD error = HardenProcessIntegrityLevelPolicy();
  66       if ((error != ERROR_SUCCESS) && (error != ERROR_ACCESS_DENIED))
  67         return false;
  68   }
  69
  70 #if !defined(_WIN64)  // DEP is always enabled on 64-bit.
  71   if (flags & MITIGATION_DEP) {
  72     DWORD dep_flags = PROCESS_DEP_ENABLE;
  73     // DEP support is quirky on XP, so don't force a failure in that case.
  74     const bool return_on_fail = version >= base::win::VERSION_VISTA;
  75
  76     if (flags & MITIGATION_DEP_NO_ATL_THUNK)
  77       dep_flags |= PROCESS_DEP_DISABLE_ATL_THUNK_EMULATION;
  78
  79     SetProcessDEPPolicyFunction set_process_dep_policy =
  80         reinterpret_cast<SetProcessDEPPolicyFunction>(
  81             ::GetProcAddress(module, "SetProcessDEPPolicy"));
  82     if (set_process_dep_policy) {
  83       if (!set_process_dep_policy(dep_flags) &&
  84           ERROR_ACCESS_DENIED != ::GetLastError() && return_on_fail) {
  85         return false;
  86       }
  87     } else {
  88       // We're on XP sp2, so use the less standard approach.
  89       // For reference: http://www.uninformed.org/?v=2&a=4
  90       static const int MEM_EXECUTE_OPTION_DISABLE = 2;
  91       static const int MEM_EXECUTE_OPTION_ATL7_THUNK_EMULATION = 4;
  92       static const int MEM_EXECUTE_OPTION_PERMANENT = 8;
  93
  94       NtSetInformationProcessFunction set_information_process = NULL;
  95       ResolveNTFunctionPtr("NtSetInformationProcess",
  96                            &set_information_process);
  97       if (!set_information_process)
  98         return false;
  99       ULONG dep = MEM_EXECUTE_OPTION_DISABLE | MEM_EXECUTE_OPTION_PERMANENT;
 100       if (!(dep_flags & PROCESS_DEP_DISABLE_ATL_THUNK_EMULATION))
 101         dep |= MEM_EXECUTE_OPTION_ATL7_THUNK_EMULATION;
 102       if (!SUCCEEDED(set_information_process(GetCurrentProcess(),
 103                                              ProcessExecuteFlags,
 104                                              &dep, sizeof(dep))) &&
 105           ERROR_ACCESS_DENIED != ::GetLastError() && return_on_fail) {
 106         return false;
 107       }
 108     }
 109   }
 110 #endif
 111
 112   // This is all we can do in Win7 and below.
 113   if (version < base::win::VERSION_WIN8)
 114     return true;
 115
 116   SetProcessMitigationPolicyFunction set_process_mitigation_policy =
 117       reinterpret_cast<SetProcessMitigationPolicyFunction>(
 118           ::GetProcAddress(module, "SetProcessMitigationPolicy"));
 119   if (!set_process_mitigation_policy)
 120     return false;
 121
 122   // Enable ASLR policies.
 123   if (flags & MITIGATION_RELOCATE_IMAGE) {
 124     PROCESS_MITIGATION_ASLR_POLICY policy = {};
 125     policy.EnableForceRelocateImages = true;
 126     policy.DisallowStrippedImages = (flags &
 127         MITIGATION_RELOCATE_IMAGE_REQUIRED) ==
 128         MITIGATION_RELOCATE_IMAGE_REQUIRED;
 129
 130     if (!set_process_mitigation_policy(ProcessASLRPolicy, &policy,
 131                                        sizeof(policy)) &&
 132         ERROR_ACCESS_DENIED != ::GetLastError()) {
 133       return false;
 134     }
 135   }
 136
 137   // Enable strict handle policies.
 138   if (flags & MITIGATION_STRICT_HANDLE_CHECKS) {
 139     PROCESS_MITIGATION_STRICT_HANDLE_CHECK_POLICY policy = {};
 140     policy.HandleExceptionsPermanentlyEnabled =
 141         policy.RaiseExceptionOnInvalidHandleReference = true;
 142
 143     if (!set_process_mitigation_policy(ProcessStrictHandleCheckPolicy, &policy,
 144                                        sizeof(policy)) &&
 145         ERROR_ACCESS_DENIED != ::GetLastError()) {
 146       return false;
 147     }
 148   }
 149
 150   // Enable system call policies.
 151   if (flags & MITIGATION_WIN32K_DISABLE) {
 152     PROCESS_MITIGATION_SYSTEM_CALL_DISABLE_POLICY policy = {};
 153     policy.DisallowWin32kSystemCalls = true;
 154
 155     if (!set_process_mitigation_policy(ProcessSystemCallDisablePolicy, &policy,
 156                                        sizeof(policy)) &&
 157         ERROR_ACCESS_DENIED != ::GetLastError()) {
 158       return false;
 159     }
 160   }
 161
 162   // Enable system call policies.
 163   if (flags & MITIGATION_EXTENSION_DLL_DISABLE) {
 164     PROCESS_MITIGATION_EXTENSION_POINT_DISABLE_POLICY policy = {};
 165     policy.DisableExtensionPoints = true;
 166
 167     if (!set_process_mitigation_policy(ProcessExtensionPointDisablePolicy,
 168                                        &policy, sizeof(policy)) &&
 169         ERROR_ACCESS_DENIED != ::GetLastError()) {
 170       return false;
 171     }
 172   }
 173
 174   return true;
 175 }
 176
 177 void ConvertProcessMitigationsToPolicy(MitigationFlags flags,
 178                                        DWORD64* policy_flags, size_t* size) {
 179   base::win::Version version = base::win::GetVersion();
 180
 181   *policy_flags = 0;
 182 #if defined(_WIN64)
 183   *size = sizeof(*policy_flags);
 184 #elif defined(_M_IX86)
 185   // A 64-bit flags attribute is illegal on 32-bit Win 7 and below.
 186   if (version < base::win::VERSION_WIN8)
 187     *size = sizeof(DWORD);
 188   else
 189     *size = sizeof(*policy_flags);
 190 #else
 191 #error This platform is not supported.
 192 #endif
 193
 194   // Nothing for Win XP or Vista.
 195   if (version <= base::win::VERSION_VISTA)
 196     return;
 197
 198   // DEP and SEHOP are not valid for 64-bit Windows
 199 #if !defined(_WIN64)
 200   if (flags & MITIGATION_DEP) {
 201     *policy_flags |= PROCESS_CREATION_MITIGATION_POLICY_DEP_ENABLE;
 202     if (!(flags & MITIGATION_DEP_NO_ATL_THUNK))
 203       *policy_flags |= PROCESS_CREATION_MITIGATION_POLICY_DEP_ATL_THUNK_ENABLE;
 204   }
 205
 206   if (flags & MITIGATION_SEHOP)
 207     *policy_flags |= PROCESS_CREATION_MITIGATION_POLICY_SEHOP_ENABLE;
 208 #endif
 209
 210   // Win 7
 211   if (version < base::win::VERSION_WIN8)
 212     return;
 213
 214   if (flags & MITIGATION_RELOCATE_IMAGE) {
 215     *policy_flags |=
 216         PROCESS_CREATION_MITIGATION_POLICY_FORCE_RELOCATE_IMAGES_ALWAYS_ON;
 217     if (flags & MITIGATION_RELOCATE_IMAGE_REQUIRED) {
 218       *policy_flags |=
 219           PROCESS_CREATION_MITIGATION_POLICY_FORCE_RELOCATE_IMAGES_ALWAYS_ON_REQ_RELOCS;
 220     }
 221   }
 222
 223   if (flags & MITIGATION_HEAP_TERMINATE) {
 224     *policy_flags |=
 225         PROCESS_CREATION_MITIGATION_POLICY_HEAP_TERMINATE_ALWAYS_ON;
 226   }
 227
 228   if (flags & MITIGATION_BOTTOM_UP_ASLR) {
 229     *policy_flags |=
 230         PROCESS_CREATION_MITIGATION_POLICY_BOTTOM_UP_ASLR_ALWAYS_ON;
 231   }
 232
 233   if (flags & MITIGATION_HIGH_ENTROPY_ASLR) {
 234     *policy_flags |=
 235         PROCESS_CREATION_MITIGATION_POLICY_HIGH_ENTROPY_ASLR_ALWAYS_ON;
 236   }
 237
 238   if (flags & MITIGATION_STRICT_HANDLE_CHECKS) {
 239     *policy_flags |=
 240         PROCESS_CREATION_MITIGATION_POLICY_STRICT_HANDLE_CHECKS_ALWAYS_ON;
 241   }
 242
 243   if (flags & MITIGATION_WIN32K_DISABLE) {
 244     *policy_flags |=
 245         PROCESS_CREATION_MITIGATION_POLICY_WIN32K_SYSTEM_CALL_DISABLE_ALWAYS_ON;
 246   }
 247
 248   if (flags & MITIGATION_EXTENSION_DLL_DISABLE) {
 249     *policy_flags |=
 250         PROCESS_CREATION_MITIGATION_POLICY_EXTENSION_POINT_DISABLE_ALWAYS_ON;
 251   }
 252 }
 253
 254 MitigationFlags FilterPostStartupProcessMitigations(MitigationFlags flags) {
 255   base::win::Version version = base::win::GetVersion();
 256
 257   // Windows XP SP2+.
 258   if (version < base::win::VERSION_VISTA) {
 259     return flags & (MITIGATION_DEP |
 260                     MITIGATION_DEP_NO_ATL_THUNK);
 261   }
 262
 263   // Windows Vista
 264   if (version < base::win::VERSION_WIN7) {
 265     return flags & (MITIGATION_BOTTOM_UP_ASLR |
 266                     MITIGATION_DLL_SEARCH_ORDER |
 267                     MITIGATION_HEAP_TERMINATE);
 268   }
 269
 270   // Windows 7.
 271   if (version < base::win::VERSION_WIN8) {
 272     return flags & (MITIGATION_BOTTOM_UP_ASLR |
 273                     MITIGATION_DLL_SEARCH_ORDER |
 274                     MITIGATION_HEAP_TERMINATE);
 275   }
 276
 277   // Windows 8 and above.
 278   return flags & (MITIGATION_BOTTOM_UP_ASLR |
 279                   MITIGATION_DLL_SEARCH_ORDER);
 280 }
 281
 282 bool ApplyProcessMitigationsToSuspendedProcess(HANDLE process,
 283                                                MitigationFlags flags) {
 284 // This is a hack to fake a weak bottom-up ASLR on 32-bit Windows.
 285 #if !defined(_WIN64)
 286   if (flags & MITIGATION_BOTTOM_UP_ASLR) {
 287     unsigned int limit;
 288     rand_s(&limit);
 289     char* ptr = 0;
 290     const size_t kMask64k = 0xFFFF;
 291     // Random range (512k-16.5mb) in 64k steps.
 292     const char* end = ptr + ((((limit % 16384) + 512) * 1024) & ~kMask64k);
 293     while (ptr < end) {
 294       MEMORY_BASIC_INFORMATION memory_info;
 295       if (!::VirtualQueryEx(process, ptr, &memory_info, sizeof(memory_info)))
 296         break;
 297       size_t size = std::min((memory_info.RegionSize + kMask64k) & ~kMask64k,
 298                              static_cast<SIZE_T>(end - ptr));
 299       if (ptr && memory_info.State == MEM_FREE)
 300         ::VirtualAllocEx(process, ptr, size, MEM_RESERVE, PAGE_NOACCESS);
 301       ptr += size;
 302     }
 303   }
 304 #endif
 305
 306   return true;
 307 }
 308
 309 bool CanSetProcessMitigationsPostStartup(MitigationFlags flags) {
 310   // All of these mitigations can be enabled after startup.
 311   return !(flags & ~(MITIGATION_HEAP_TERMINATE |
 312                      MITIGATION_DEP |
 313                      MITIGATION_DEP_NO_ATL_THUNK |
 314                      MITIGATION_RELOCATE_IMAGE |
 315                      MITIGATION_RELOCATE_IMAGE_REQUIRED |
 316                      MITIGATION_BOTTOM_UP_ASLR |
 317                      MITIGATION_STRICT_HANDLE_CHECKS |
 318                      MITIGATION_EXTENSION_DLL_DISABLE |
 319                      MITIGATION_DLL_SEARCH_ORDER |
 320                      MITIGATION_HARDEN_TOKEN_IL_POLICY));
 321 }
 322
 323 bool CanSetProcessMitigationsPreStartup(MitigationFlags flags) {
 324   // These mitigations cannot be enabled prior to startup.
 325   return !(flags & (MITIGATION_STRICT_HANDLE_CHECKS |
 326                     MITIGATION_DLL_SEARCH_ORDER));
 327 }
 328
 329 }  // namespace sandbox
 330