sandbox/win/src/target_services.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/target_services.h"
   6
   7 #include <new>
   8
   9 #include <process.h>
  10
  11 #include "base/basictypes.h"
  12 #include "base/win/windows_version.h"
  13 #include "sandbox/win/src/crosscall_client.h"
  14 #include "sandbox/win/src/handle_closer_agent.h"
  15 #include "sandbox/win/src/handle_interception.h"
  16 #include "sandbox/win/src/ipc_tags.h"
  17 #include "sandbox/win/src/process_mitigations.h"
  18 #include "sandbox/win/src/restricted_token_utils.h"
  19 #include "sandbox/win/src/sandbox.h"
  20 #include "sandbox/win/src/sandbox_types.h"
  21 #include "sandbox/win/src/sharedmem_ipc_client.h"
  22 #include "sandbox/win/src/sandbox_nt_util.h"
  23
  24 namespace {
  25
  26 // Flushing a cached key is triggered by just opening the key and closing the
  27 // resulting handle. RegDisablePredefinedCache() is the documented way to flush
  28 // HKCU so do not use it with this function.
  29 bool FlushRegKey(HKEY root) {
  30   HKEY key;
  31   if (ERROR_SUCCESS == ::RegOpenKeyExW(root, NULL, 0, MAXIMUM_ALLOWED, &key)) {
  32     if (ERROR_SUCCESS != ::RegCloseKey(key))
  33       return false;
  34   }
  35   return true;
  36 }
  37
  38 // This function forces advapi32.dll to release some internally cached handles
  39 // that were made during calls to RegOpenkey and RegOpenKeyEx if it is called
  40 // with a more restrictive token. Returns true if the flushing is succesful
  41 // although this behavior is undocumented and there is no guarantee that in
  42 // fact this will happen in future versions of windows.
  43 bool FlushCachedRegHandles() {
  44   return (FlushRegKey(HKEY_LOCAL_MACHINE) &&
  45           FlushRegKey(HKEY_CLASSES_ROOT) &&
  46           FlushRegKey(HKEY_USERS));
  47 }
  48
  49 // Checks if we have handle entries pending and runs the closer.
  50 bool CloseOpenHandles() {
  51   if (sandbox::HandleCloserAgent::NeedsHandlesClosed()) {
  52     sandbox::HandleCloserAgent handle_closer;
  53
  54     handle_closer.InitializeHandlesToClose();
  55     if (!handle_closer.CloseHandles())
  56       return false;
  57   }
  58
  59   return true;
  60 }
  61
  62 // Used as storage for g_target_services, because other allocation facilities
  63 // are not available early. We can't use a regular function static because on
  64 // VS2015, because the CRT tries to acquire a lock to guard initialization, but
  65 // this code runs before the CRT is initialized.
  66 char g_target_services_memory[sizeof(sandbox::TargetServicesBase)];
  67 sandbox::TargetServicesBase* g_target_services = nullptr;
  68
  69 }  // namespace
  70
  71 namespace sandbox {
  72
  73 SANDBOX_INTERCEPT IntegrityLevel g_shared_delayed_integrity_level =
  74     INTEGRITY_LEVEL_LAST;
  75 SANDBOX_INTERCEPT MitigationFlags g_shared_delayed_mitigations = 0;
  76
  77 TargetServicesBase::TargetServicesBase() {
  78 }
  79
  80 ResultCode TargetServicesBase::Init() {
  81   process_state_.SetInitCalled();
  82   return SBOX_ALL_OK;
  83 }
  84
  85 // Failure here is a breach of security so the process is terminated.
  86 void TargetServicesBase::LowerToken() {
  87   if (ERROR_SUCCESS !=
  88       SetProcessIntegrityLevel(g_shared_delayed_integrity_level))
  89     ::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_INTEGRITY);
  90   process_state_.SetRevertedToSelf();
  91   // If the client code as called RegOpenKey, advapi32.dll has cached some
  92   // handles. The following code gets rid of them.
  93   if (!::RevertToSelf())
  94     ::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_DROPTOKEN);
  95   if (!FlushCachedRegHandles())
  96     ::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_FLUSHANDLES);
  97   if (ERROR_SUCCESS != ::RegDisablePredefinedCache())
  98     ::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_CACHEDISABLE);
  99   if (!CloseOpenHandles())
 100     ::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_CLOSEHANDLES);
 101   // Enabling mitigations must happen last otherwise handle closing breaks
 102   if (g_shared_delayed_mitigations &&
 103       !ApplyProcessMitigationsToCurrentProcess(g_shared_delayed_mitigations))
 104     ::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_MITIGATION);
 105 }
 106
 107 ProcessState* TargetServicesBase::GetState() {
 108   return &process_state_;
 109 }
 110
 111 TargetServicesBase* TargetServicesBase::GetInstance() {
 112   // Leak on purpose TargetServicesBase.
 113   if (!g_target_services)
 114     g_target_services = new (g_target_services_memory) TargetServicesBase;
 115   return g_target_services;
 116 }
 117
 118 // The broker services a 'test' IPC service with the IPC_PING_TAG tag.
 119 bool TargetServicesBase::TestIPCPing(int version) {
 120   void* memory = GetGlobalIPCMemory();
 121   if (NULL == memory) {
 122     return false;
 123   }
 124   SharedMemIPCClient ipc(memory);
 125   CrossCallReturn answer = {0};
 126
 127   if (1 == version) {
 128     uint32 tick1 = ::GetTickCount();
 129     uint32 cookie = 717115;
 130     ResultCode code = CrossCall(ipc, IPC_PING1_TAG, cookie, &answer);
 131
 132     if (SBOX_ALL_OK != code) {
 133       return false;
 134     }
 135     // We should get two extended returns values from the IPC, one is the
 136     // tick count on the broker and the other is the cookie times two.
 137     if ((answer.extended_count != 2)) {
 138       return false;
 139     }
 140     // We test the first extended answer to be within the bounds of the tick
 141     // count only if there was no tick count wraparound.
 142     uint32 tick2 = ::GetTickCount();
 143     if (tick2 >= tick1) {
 144       if ((answer.extended[0].unsigned_int < tick1) ||
 145           (answer.extended[0].unsigned_int > tick2)) {
 146         return false;
 147       }
 148     }
 149
 150     if (answer.extended[1].unsigned_int != cookie * 2) {
 151       return false;
 152     }
 153   } else if (2 == version) {
 154     uint32 cookie = 717111;
 155     InOutCountedBuffer counted_buffer(&cookie, sizeof(cookie));
 156     ResultCode code = CrossCall(ipc, IPC_PING2_TAG, counted_buffer, &answer);
 157
 158     if (SBOX_ALL_OK != code) {
 159       return false;
 160     }
 161     if (cookie != 717111 * 3) {
 162       return false;
 163     }
 164   } else {
 165     return false;
 166   }
 167   return true;
 168 }
 169
 170 ProcessState::ProcessState() : process_state_(0) {
 171 }
 172
 173 bool ProcessState::IsKernel32Loaded() const {
 174   return process_state_ != 0;
 175 }
 176
 177 bool ProcessState::InitCalled() const {
 178   return process_state_ > 1;
 179 }
 180
 181 bool ProcessState::RevertedToSelf() const {
 182   return process_state_ > 2;
 183 }
 184
 185 void ProcessState::SetKernel32Loaded() {
 186   if (!process_state_)
 187     process_state_ = 1;
 188 }
 189
 190 void ProcessState::SetInitCalled() {
 191   if (process_state_ < 2)
 192     process_state_ = 2;
 193 }
 194
 195 void ProcessState::SetRevertedToSelf() {
 196   if (process_state_ < 3)
 197     process_state_ = 3;
 198 }
 199
 200 ResultCode TargetServicesBase::DuplicateHandle(HANDLE source_handle,
 201                                                DWORD target_process_id,
 202                                                HANDLE* target_handle,
 203                                                DWORD desired_access,
 204                                                DWORD options) {
 205   return sandbox::DuplicateHandleProxy(source_handle, target_process_id,
 206                                        target_handle, desired_access, options);
 207 }
 208
 209 }  // namespace sandbox