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 // Updates is_csrss_connected based on which handle types are closed.
  51 bool CloseOpenHandles(bool* is_csrss_connected) {
  52   if (sandbox::HandleCloserAgent::NeedsHandlesClosed()) {
  53     sandbox::HandleCloserAgent handle_closer;
  54     handle_closer.InitializeHandlesToClose(is_csrss_connected);
  55     if (!handle_closer.CloseHandles())
  56       return false;
  57   }
  58
  59   return true;
  60 }
  61
  62
  63 // Used as storage for g_target_services, because other allocation facilities
  64 // are not available early. We can't use a regular function static because on
  65 // VS2015, because the CRT tries to acquire a lock to guard initialization, but
  66 // this code runs before the CRT is initialized.
  67 char g_target_services_memory[sizeof(sandbox::TargetServicesBase)];
  68 sandbox::TargetServicesBase* g_target_services = nullptr;
  69
  70 }  // namespace
  71
  72 namespace sandbox {
  73
  74 SANDBOX_INTERCEPT IntegrityLevel g_shared_delayed_integrity_level =
  75     INTEGRITY_LEVEL_LAST;
  76 SANDBOX_INTERCEPT MitigationFlags g_shared_delayed_mitigations = 0;
  77
  78 TargetServicesBase::TargetServicesBase() {
  79 }
  80
  81 ResultCode TargetServicesBase::Init() {
  82   process_state_.SetInitCalled();
  83   return SBOX_ALL_OK;
  84 }
  85
  86 // Failure here is a breach of security so the process is terminated.
  87 void TargetServicesBase::LowerToken() {
  88   if (ERROR_SUCCESS !=
  89       SetProcessIntegrityLevel(g_shared_delayed_integrity_level))
  90     ::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_INTEGRITY);
  91   process_state_.SetRevertedToSelf();
  92   // If the client code as called RegOpenKey, advapi32.dll has cached some
  93   // handles. The following code gets rid of them.
  94   if (!::RevertToSelf())
  95     ::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_DROPTOKEN);
  96   if (!FlushCachedRegHandles())
  97     ::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_FLUSHANDLES);
  98   if (ERROR_SUCCESS != ::RegDisablePredefinedCache())
  99     ::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_CACHEDISABLE);
 100   bool is_csrss_connected = true;
 101   if (!CloseOpenHandles(&is_csrss_connected))
 102     ::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_CLOSEHANDLES);
 103   process_state_.SetCsrssConnected(is_csrss_connected);
 104   // Enabling mitigations must happen last otherwise handle closing breaks
 105   if (g_shared_delayed_mitigations &&
 106       !ApplyProcessMitigationsToCurrentProcess(g_shared_delayed_mitigations))
 107     ::TerminateProcess(::GetCurrentProcess(), SBOX_FATAL_MITIGATION);
 108 }
 109
 110 ProcessState* TargetServicesBase::GetState() {
 111   return &process_state_;
 112 }
 113
 114 TargetServicesBase* TargetServicesBase::GetInstance() {
 115   // Leak on purpose TargetServicesBase.
 116   if (!g_target_services)
 117     g_target_services = new (g_target_services_memory) TargetServicesBase;
 118   return g_target_services;
 119 }
 120
 121 // The broker services a 'test' IPC service with the IPC_PING_TAG tag.
 122 bool TargetServicesBase::TestIPCPing(int version) {
 123   void* memory = GetGlobalIPCMemory();
 124   if (NULL == memory) {
 125     return false;
 126   }
 127   SharedMemIPCClient ipc(memory);
 128   CrossCallReturn answer = {0};
 129
 130   if (1 == version) {
 131     uint32 tick1 = ::GetTickCount();
 132     uint32 cookie = 717115;
 133     ResultCode code = CrossCall(ipc, IPC_PING1_TAG, cookie, &answer);
 134
 135     if (SBOX_ALL_OK != code) {
 136       return false;
 137     }
 138     // We should get two extended returns values from the IPC, one is the
 139     // tick count on the broker and the other is the cookie times two.
 140     if ((answer.extended_count != 2)) {
 141       return false;
 142     }
 143     // We test the first extended answer to be within the bounds of the tick
 144     // count only if there was no tick count wraparound.
 145     uint32 tick2 = ::GetTickCount();
 146     if (tick2 >= tick1) {
 147       if ((answer.extended[0].unsigned_int < tick1) ||
 148           (answer.extended[0].unsigned_int > tick2)) {
 149         return false;
 150       }
 151     }
 152
 153     if (answer.extended[1].unsigned_int != cookie * 2) {
 154       return false;
 155     }
 156   } else if (2 == version) {
 157     uint32 cookie = 717111;
 158     InOutCountedBuffer counted_buffer(&cookie, sizeof(cookie));
 159     ResultCode code = CrossCall(ipc, IPC_PING2_TAG, counted_buffer, &answer);
 160
 161     if (SBOX_ALL_OK != code) {
 162       return false;
 163     }
 164     if (cookie != 717111 * 3) {
 165       return false;
 166     }
 167   } else {
 168     return false;
 169   }
 170   return true;
 171 }
 172
 173 ProcessState::ProcessState() : process_state_(0), csrss_connected_(true) {
 174 }
 175
 176 bool ProcessState::IsKernel32Loaded() const {
 177   return process_state_ != 0;
 178 }
 179
 180 bool ProcessState::InitCalled() const {
 181   return process_state_ > 1;
 182 }
 183
 184 bool ProcessState::RevertedToSelf() const {
 185   return process_state_ > 2;
 186 }
 187
 188 bool ProcessState::IsCsrssConnected() const {
 189   return csrss_connected_;
 190 }
 191
 192 void ProcessState::SetKernel32Loaded() {
 193   if (!process_state_)
 194     process_state_ = 1;
 195 }
 196
 197 void ProcessState::SetInitCalled() {
 198   if (process_state_ < 2)
 199     process_state_ = 2;
 200 }
 201
 202 void ProcessState::SetRevertedToSelf() {
 203   if (process_state_ < 3)
 204     process_state_ = 3;
 205 }
 206
 207 void ProcessState::SetCsrssConnected(bool csrss_connected) {
 208   csrss_connected_ = csrss_connected;
 209 }
 210
 211
 212 ResultCode TargetServicesBase::DuplicateHandle(HANDLE source_handle,
 213                                                DWORD target_process_id,
 214                                                HANDLE* target_handle,
 215                                                DWORD desired_access,
 216                                                DWORD options) {
 217   return sandbox::DuplicateHandleProxy(source_handle, target_process_id,
 218                                        target_handle, desired_access, options);
 219 }
 220
 221 }  // namespace sandbox