sandbox/win/src/broker_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/broker_services.h"
   6
   7 #include <AclAPI.h>
   8
   9 #include "base/logging.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/threading/platform_thread.h"
  12 #include "base/win/scoped_handle.h"
  13 #include "base/win/scoped_process_information.h"
  14 #include "base/win/startup_information.h"
  15 #include "base/win/windows_version.h"
  16 #include "sandbox/win/src/app_container.h"
  17 #include "sandbox/win/src/process_mitigations.h"
  18 #include "sandbox/win/src/sandbox_policy_base.h"
  19 #include "sandbox/win/src/sandbox.h"
  20 #include "sandbox/win/src/target_process.h"
  21 #include "sandbox/win/src/win2k_threadpool.h"
  22 #include "sandbox/win/src/win_utils.h"
  23
  24 namespace {
  25
  26 // Utility function to associate a completion port to a job object.
  27 bool AssociateCompletionPort(HANDLE job, HANDLE port, void* key) {
  28   JOBOBJECT_ASSOCIATE_COMPLETION_PORT job_acp = { key, port };
  29   return ::SetInformationJobObject(job,
  30                                    JobObjectAssociateCompletionPortInformation,
  31                                    &job_acp, sizeof(job_acp))? true : false;
  32 }
  33
  34 // Utility function to do the cleanup necessary when something goes wrong
  35 // while in SpawnTarget and we must terminate the target process.
  36 sandbox::ResultCode SpawnCleanup(sandbox::TargetProcess* target, DWORD error) {
  37   if (0 == error)
  38     error = ::GetLastError();
  39
  40   target->Terminate();
  41   delete target;
  42   ::SetLastError(error);
  43   return sandbox::SBOX_ERROR_GENERIC;
  44 }
  45
  46 // the different commands that you can send to the worker thread that
  47 // executes TargetEventsThread().
  48 enum {
  49   THREAD_CTRL_NONE,
  50   THREAD_CTRL_REMOVE_PEER,
  51   THREAD_CTRL_QUIT,
  52   THREAD_CTRL_LAST,
  53 };
  54
  55 // Helper structure that allows the Broker to associate a job notification
  56 // with a job object and with a policy.
  57 struct JobTracker {
  58   HANDLE job;
  59   sandbox::PolicyBase* policy;
  60   JobTracker(HANDLE cjob, sandbox::PolicyBase* cpolicy)
  61       : job(cjob), policy(cpolicy) {
  62   }
  63 };
  64
  65 // Helper structure that allows the broker to track peer processes
  66 struct PeerTracker {
  67   HANDLE wait_object;
  68   base::win::ScopedHandle process;
  69   DWORD id;
  70   HANDLE job_port;
  71   PeerTracker(DWORD process_id, HANDLE broker_job_port)
  72       : wait_object(NULL), id(process_id), job_port(broker_job_port) {
  73   }
  74 };
  75
  76 void DeregisterPeerTracker(PeerTracker* peer) {
  77   // Deregistration shouldn't fail, but we leak rather than crash if it does.
  78   if (::UnregisterWaitEx(peer->wait_object, INVALID_HANDLE_VALUE)) {
  79     delete peer;
  80   } else {
  81     NOTREACHED();
  82   }
  83 }
  84
  85 // Utility function to pack token values into a key for the cache map.
  86 uint32_t GenerateTokenCacheKey(const sandbox::PolicyBase* policy) {
  87   const size_t kTokenShift = 3;
  88   uint32_t key;
  89
  90   // Make sure our token values aren't too large to pack into the key.
  91   static_assert(sandbox::USER_LAST <= (1 << kTokenShift),
  92                 "TokenLevel too large");
  93   static_assert(sandbox::INTEGRITY_LEVEL_LAST <= (1 << kTokenShift),
  94                 "IntegrityLevel too large");
  95   static_assert(sizeof(key) < (kTokenShift * 3),
  96                 "Token key type too small");
  97
  98   // The key is the enum values shifted to avoid overlap and OR'd together.
  99   key = policy->GetInitialTokenLevel();
 100   key <<= kTokenShift;
 101   key |= policy->GetLockdownTokenLevel();
 102   key <<= kTokenShift;
 103   key |= policy->GetIntegrityLevel();
 104
 105   return key;
 106 }
 107
 108 }  // namespace
 109
 110 namespace sandbox {
 111
 112 BrokerServicesBase::BrokerServicesBase()
 113     : thread_pool_(NULL), job_port_(NULL), no_targets_(NULL),
 114       job_thread_(NULL) {
 115 }
 116
 117 // The broker uses a dedicated worker thread that services the job completion
 118 // port to perform policy notifications and associated cleanup tasks.
 119 ResultCode BrokerServicesBase::Init() {
 120   if ((NULL != job_port_) || (NULL != thread_pool_))
 121     return SBOX_ERROR_UNEXPECTED_CALL;
 122
 123   ::InitializeCriticalSection(&lock_);
 124
 125   job_port_ = ::CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 0);
 126   if (NULL == job_port_)
 127     return SBOX_ERROR_GENERIC;
 128
 129   no_targets_ = ::CreateEventW(NULL, TRUE, FALSE, NULL);
 130
 131   job_thread_ = ::CreateThread(NULL, 0,  // Default security and stack.
 132                                TargetEventsThread, this, NULL, NULL);
 133   if (NULL == job_thread_)
 134     return SBOX_ERROR_GENERIC;
 135
 136   return SBOX_ALL_OK;
 137 }
 138
 139 // The destructor should only be called when the Broker process is terminating.
 140 // Since BrokerServicesBase is a singleton, this is called from the CRT
 141 // termination handlers, if this code lives on a DLL it is called during
 142 // DLL_PROCESS_DETACH in other words, holding the loader lock, so we cannot
 143 // wait for threads here.
 144 BrokerServicesBase::~BrokerServicesBase() {
 145   // If there is no port Init() was never called successfully.
 146   if (!job_port_)
 147     return;
 148
 149   // Closing the port causes, that no more Job notifications are delivered to
 150   // the worker thread and also causes the thread to exit. This is what we
 151   // want to do since we are going to close all outstanding Jobs and notifying
 152   // the policy objects ourselves.
 153   ::PostQueuedCompletionStatus(job_port_, 0, THREAD_CTRL_QUIT, FALSE);
 154   ::CloseHandle(job_port_);
 155
 156   if (WAIT_TIMEOUT == ::WaitForSingleObject(job_thread_, 1000)) {
 157     // Cannot clean broker services.
 158     NOTREACHED();
 159     return;
 160   }
 161
 162   JobTrackerList::iterator it;
 163   for (it = tracker_list_.begin(); it != tracker_list_.end(); ++it) {
 164     JobTracker* tracker = (*it);
 165     FreeResources(tracker);
 166     delete tracker;
 167   }
 168   ::CloseHandle(job_thread_);
 169   delete thread_pool_;
 170   ::CloseHandle(no_targets_);
 171
 172   // Cancel the wait events and delete remaining peer trackers.
 173   for (PeerTrackerMap::iterator it = peer_map_.begin();
 174        it != peer_map_.end(); ++it) {
 175     DeregisterPeerTracker(it->second);
 176   }
 177
 178   // If job_port_ isn't NULL, assumes that the lock has been initialized.
 179   if (job_port_)
 180     ::DeleteCriticalSection(&lock_);
 181
 182   // Close any token in the cache.
 183   for (TokenCacheMap::iterator it = token_cache_.begin();
 184        it != token_cache_.end(); ++it) {
 185     ::CloseHandle(it->second.first);
 186     ::CloseHandle(it->second.second);
 187   }
 188 }
 189
 190 TargetPolicy* BrokerServicesBase::CreatePolicy() {
 191   // If you change the type of the object being created here you must also
 192   // change the downcast to it in SpawnTarget().
 193   return new PolicyBase;
 194 }
 195
 196 void BrokerServicesBase::FreeResources(JobTracker* tracker) {
 197   if (NULL != tracker->policy) {
 198     BOOL res = ::TerminateJobObject(tracker->job, SBOX_ALL_OK);
 199     DCHECK(res);
 200     // Closing the job causes the target process to be destroyed so this
 201     // needs to happen before calling OnJobEmpty().
 202     res = ::CloseHandle(tracker->job);
 203     DCHECK(res);
 204     // In OnJobEmpty() we don't actually use the job handle directly.
 205     tracker->policy->OnJobEmpty(tracker->job);
 206     tracker->policy->Release();
 207     tracker->policy = NULL;
 208   }
 209 }
 210
 211 // The worker thread stays in a loop waiting for asynchronous notifications
 212 // from the job objects. Right now we only care about knowing when the last
 213 // process on a job terminates, but in general this is the place to tell
 214 // the policy about events.
 215 DWORD WINAPI BrokerServicesBase::TargetEventsThread(PVOID param) {
 216   if (NULL == param)
 217     return 1;
 218
 219   base::PlatformThread::SetName("BrokerEvent");
 220
 221   BrokerServicesBase* broker = reinterpret_cast<BrokerServicesBase*>(param);
 222   HANDLE port = broker->job_port_;
 223   HANDLE no_targets = broker->no_targets_;
 224
 225   int target_counter = 0;
 226   ::ResetEvent(no_targets);
 227
 228   while (true) {
 229     DWORD events = 0;
 230     ULONG_PTR key = 0;
 231     LPOVERLAPPED ovl = NULL;
 232
 233     if (!::GetQueuedCompletionStatus(port, &events, &key, &ovl, INFINITE))
 234       // this call fails if the port has been closed before we have a
 235       // chance to service the last packet which is 'exit' anyway so
 236       // this is not an error.
 237       return 1;
 238
 239     if (key > THREAD_CTRL_LAST) {
 240       // The notification comes from a job object. There are nine notifications
 241       // that jobs can send and some of them depend on the job attributes set.
 242       JobTracker* tracker = reinterpret_cast<JobTracker*>(key);
 243
 244       switch (events) {
 245         case JOB_OBJECT_MSG_ACTIVE_PROCESS_ZERO: {
 246           // The job object has signaled that the last process associated
 247           // with it has terminated. Assuming there is no way for a process
 248           // to appear out of thin air in this job, it safe to assume that
 249           // we can tell the policy to destroy the target object, and for
 250           // us to release our reference to the policy object.
 251           FreeResources(tracker);
 252           break;
 253         }
 254
 255         case JOB_OBJECT_MSG_NEW_PROCESS: {
 256           ++target_counter;
 257           if (1 == target_counter) {
 258             ::ResetEvent(no_targets);
 259           }
 260           break;
 261         }
 262
 263         case JOB_OBJECT_MSG_EXIT_PROCESS:
 264         case JOB_OBJECT_MSG_ABNORMAL_EXIT_PROCESS: {
 265           {
 266             AutoLock lock(&broker->lock_);
 267             broker->child_process_ids_.erase(reinterpret_cast<DWORD>(ovl));
 268           }
 269           --target_counter;
 270           if (0 == target_counter)
 271             ::SetEvent(no_targets);
 272
 273           DCHECK(target_counter >= 0);
 274           break;
 275         }
 276
 277         case JOB_OBJECT_MSG_ACTIVE_PROCESS_LIMIT: {
 278           break;
 279         }
 280
 281         case JOB_OBJECT_MSG_PROCESS_MEMORY_LIMIT: {
 282           BOOL res = ::TerminateJobObject(tracker->job,
 283                                           SBOX_FATAL_MEMORY_EXCEEDED);
 284           DCHECK(res);
 285           break;
 286         }
 287
 288         default: {
 289           NOTREACHED();
 290           break;
 291         }
 292       }
 293     } else if (THREAD_CTRL_REMOVE_PEER == key) {
 294       // Remove a process from our list of peers.
 295       AutoLock lock(&broker->lock_);
 296       PeerTrackerMap::iterator it =
 297           broker->peer_map_.find(reinterpret_cast<DWORD>(ovl));
 298       DeregisterPeerTracker(it->second);
 299       broker->peer_map_.erase(it);
 300     } else if (THREAD_CTRL_QUIT == key) {
 301       // The broker object is being destroyed so the thread needs to exit.
 302       return 0;
 303     } else {
 304       // We have not implemented more commands.
 305       NOTREACHED();
 306     }
 307   }
 308
 309   NOTREACHED();
 310   return 0;
 311 }
 312
 313 // SpawnTarget does all the interesting sandbox setup and creates the target
 314 // process inside the sandbox.
 315 ResultCode BrokerServicesBase::SpawnTarget(const wchar_t* exe_path,
 316                                            const wchar_t* command_line,
 317                                            TargetPolicy* policy,
 318                                            PROCESS_INFORMATION* target_info) {
 319   if (!exe_path)
 320     return SBOX_ERROR_BAD_PARAMS;
 321
 322   if (!policy)
 323     return SBOX_ERROR_BAD_PARAMS;
 324
 325   // Even though the resources touched by SpawnTarget can be accessed in
 326   // multiple threads, the method itself cannot be called from more than
 327   // 1 thread. This is to protect the global variables used while setting up
 328   // the child process.
 329   static DWORD thread_id = ::GetCurrentThreadId();
 330   DCHECK(thread_id == ::GetCurrentThreadId());
 331
 332   AutoLock lock(&lock_);
 333
 334   // This downcast is safe as long as we control CreatePolicy()
 335   PolicyBase* policy_base = static_cast<PolicyBase*>(policy);
 336
 337   // Construct the tokens and the job object that we are going to associate
 338   // with the soon to be created target process.
 339   HANDLE initial_token_temp;
 340   HANDLE lockdown_token_temp;
 341   ResultCode result = SBOX_ALL_OK;
 342
 343   // Create the master tokens only once and save them in a cache. That way
 344   // can just duplicate them to avoid hammering LSASS on every sandboxed
 345   // process launch.
 346   uint32_t token_key = GenerateTokenCacheKey(policy_base);
 347   TokenCacheMap::iterator it = token_cache_.find(token_key);
 348   if (it != token_cache_.end()) {
 349     initial_token_temp = it->second.first;
 350     lockdown_token_temp = it->second.second;
 351   } else {
 352     result = policy_base->MakeTokens(&initial_token_temp,
 353                                      &lockdown_token_temp);
 354     if (SBOX_ALL_OK != result)
 355       return result;
 356     token_cache_[token_key] =
 357         std::pair<HANDLE, HANDLE>(initial_token_temp, lockdown_token_temp);
 358   }
 359
 360   if (!::DuplicateToken(initial_token_temp, SecurityImpersonation,
 361                         &initial_token_temp)) {
 362     return SBOX_ERROR_GENERIC;
 363   }
 364
 365   if (!::DuplicateTokenEx(lockdown_token_temp, TOKEN_ALL_ACCESS, 0,
 366                           SecurityIdentification, TokenPrimary,
 367                           &lockdown_token_temp)) {
 368     return SBOX_ERROR_GENERIC;
 369   }
 370
 371   base::win::ScopedHandle initial_token(initial_token_temp);
 372   base::win::ScopedHandle lockdown_token(lockdown_token_temp);
 373
 374   HANDLE job_temp;
 375   result = policy_base->MakeJobObject(&job_temp);
 376   if (SBOX_ALL_OK != result)
 377     return result;
 378
 379   base::win::ScopedHandle job(job_temp);
 380
 381   // Initialize the startup information from the policy.
 382   base::win::StartupInformation startup_info;
 383   base::string16 desktop = policy_base->GetAlternateDesktop();
 384   if (!desktop.empty()) {
 385     startup_info.startup_info()->lpDesktop =
 386         const_cast<wchar_t*>(desktop.c_str());
 387   }
 388
 389   bool inherit_handles = false;
 390   if (base::win::GetVersion() >= base::win::VERSION_VISTA) {
 391     int attribute_count = 0;
 392     const AppContainerAttributes* app_container =
 393         policy_base->GetAppContainer();
 394     if (app_container)
 395       ++attribute_count;
 396
 397     DWORD64 mitigations;
 398     size_t mitigations_size;
 399     ConvertProcessMitigationsToPolicy(policy->GetProcessMitigations(),
 400                                       &mitigations, &mitigations_size);
 401     if (mitigations)
 402       ++attribute_count;
 403
 404     HANDLE stdout_handle = policy_base->GetStdoutHandle();
 405     HANDLE stderr_handle = policy_base->GetStderrHandle();
 406     HANDLE inherit_handle_list[2];
 407     int inherit_handle_count = 0;
 408     if (stdout_handle != INVALID_HANDLE_VALUE)
 409       inherit_handle_list[inherit_handle_count++] = stdout_handle;
 410     // Handles in the list must be unique.
 411     if (stderr_handle != stdout_handle && stderr_handle != INVALID_HANDLE_VALUE)
 412       inherit_handle_list[inherit_handle_count++] = stderr_handle;
 413     if (inherit_handle_count)
 414       ++attribute_count;
 415
 416     if (!startup_info.InitializeProcThreadAttributeList(attribute_count))
 417       return SBOX_ERROR_PROC_THREAD_ATTRIBUTES;
 418
 419     if (app_container) {
 420       result = app_container->ShareForStartup(&startup_info);
 421       if (SBOX_ALL_OK != result)
 422         return result;
 423     }
 424
 425     if (mitigations) {
 426       if (!startup_info.UpdateProcThreadAttribute(
 427                PROC_THREAD_ATTRIBUTE_MITIGATION_POLICY, &mitigations,
 428                mitigations_size)) {
 429         return SBOX_ERROR_PROC_THREAD_ATTRIBUTES;
 430       }
 431     }
 432
 433     if (inherit_handle_count) {
 434       if (!startup_info.UpdateProcThreadAttribute(
 435               PROC_THREAD_ATTRIBUTE_HANDLE_LIST,
 436               inherit_handle_list,
 437               sizeof(inherit_handle_list[0]) * inherit_handle_count)) {
 438         return SBOX_ERROR_PROC_THREAD_ATTRIBUTES;
 439       }
 440       startup_info.startup_info()->dwFlags |= STARTF_USESTDHANDLES;
 441       startup_info.startup_info()->hStdInput = INVALID_HANDLE_VALUE;
 442       startup_info.startup_info()->hStdOutput = stdout_handle;
 443       startup_info.startup_info()->hStdError = stderr_handle;
 444       // Allowing inheritance of handles is only secure now that we
 445       // have limited which handles will be inherited.
 446       inherit_handles = true;
 447     }
 448   }
 449
 450   // Construct the thread pool here in case it is expensive.
 451   // The thread pool is shared by all the targets
 452   if (NULL == thread_pool_)
 453     thread_pool_ = new Win2kThreadPool();
 454
 455   // Create the TargetProces object and spawn the target suspended. Note that
 456   // Brokerservices does not own the target object. It is owned by the Policy.
 457   base::win::ScopedProcessInformation process_info;
 458   TargetProcess* target = new TargetProcess(initial_token.Take(),
 459                                             lockdown_token.Take(),
 460                                             job,
 461                                             thread_pool_);
 462
 463   DWORD win_result = target->Create(exe_path, command_line, inherit_handles,
 464                                     startup_info, &process_info);
 465   if (ERROR_SUCCESS != win_result)
 466     return SpawnCleanup(target, win_result);
 467
 468   // Now the policy is the owner of the target.
 469   if (!policy_base->AddTarget(target)) {
 470     return SpawnCleanup(target, 0);
 471   }
 472
 473   // We are going to keep a pointer to the policy because we'll call it when
 474   // the job object generates notifications using the completion port.
 475   policy_base->AddRef();
 476   if (job.IsValid()) {
 477     scoped_ptr<JobTracker> tracker(new JobTracker(job.Take(), policy_base));
 478     if (!AssociateCompletionPort(tracker->job, job_port_, tracker.get()))
 479       return SpawnCleanup(target, 0);
 480     // Save the tracker because in cleanup we might need to force closing
 481     // the Jobs.
 482     tracker_list_.push_back(tracker.release());
 483     child_process_ids_.insert(process_info.process_id());
 484   } else {
 485     // We have to signal the event once here because the completion port will
 486     // never get a message that this target is being terminated thus we should
 487     // not block WaitForAllTargets until we have at least one target with job.
 488     if (child_process_ids_.empty())
 489       ::SetEvent(no_targets_);
 490     // We can not track the life time of such processes and it is responsibility
 491     // of the host application to make sure that spawned targets without jobs
 492     // are terminated when the main application don't need them anymore.
 493   }
 494
 495   *target_info = process_info.Take();
 496   return SBOX_ALL_OK;
 497 }
 498
 499
 500 ResultCode BrokerServicesBase::WaitForAllTargets() {
 501   ::WaitForSingleObject(no_targets_, INFINITE);
 502   return SBOX_ALL_OK;
 503 }
 504
 505 bool BrokerServicesBase::IsActiveTarget(DWORD process_id) {
 506   AutoLock lock(&lock_);
 507   return child_process_ids_.find(process_id) != child_process_ids_.end() ||
 508          peer_map_.find(process_id) != peer_map_.end();
 509 }
 510
 511 VOID CALLBACK BrokerServicesBase::RemovePeer(PVOID parameter, BOOLEAN timeout) {
 512   PeerTracker* peer = reinterpret_cast<PeerTracker*>(parameter);
 513   // Don't check the return code because we this may fail (safely) at shutdown.
 514   ::PostQueuedCompletionStatus(peer->job_port, 0, THREAD_CTRL_REMOVE_PEER,
 515                                reinterpret_cast<LPOVERLAPPED>(peer->id));
 516 }
 517
 518 ResultCode BrokerServicesBase::AddTargetPeer(HANDLE peer_process) {
 519   scoped_ptr<PeerTracker> peer(new PeerTracker(::GetProcessId(peer_process),
 520                                                job_port_));
 521   if (!peer->id)
 522     return SBOX_ERROR_GENERIC;
 523
 524   HANDLE process_handle;
 525   if (!::DuplicateHandle(::GetCurrentProcess(), peer_process,
 526                          ::GetCurrentProcess(), &process_handle,
 527                          SYNCHRONIZE, FALSE, 0)) {
 528     return SBOX_ERROR_GENERIC;
 529   }
 530   peer->process.Set(process_handle);
 531
 532   AutoLock lock(&lock_);
 533   if (!peer_map_.insert(std::make_pair(peer->id, peer.get())).second)
 534     return SBOX_ERROR_BAD_PARAMS;
 535
 536   if (!::RegisterWaitForSingleObject(
 537           &peer->wait_object, peer->process, RemovePeer, peer.get(), INFINITE,
 538           WT_EXECUTEONLYONCE | WT_EXECUTEINWAITTHREAD)) {
 539     peer_map_.erase(peer->id);
 540     return SBOX_ERROR_GENERIC;
 541   }
 542
 543   // Release the pointer since it will be cleaned up by the callback.
 544   peer.release();
 545   return SBOX_ALL_OK;
 546 }
 547
 548 ResultCode BrokerServicesBase::InstallAppContainer(const wchar_t* sid,
 549                                                    const wchar_t* name) {
 550   if (base::win::OSInfo::GetInstance()->version() < base::win::VERSION_WIN8)
 551     return SBOX_ERROR_UNSUPPORTED;
 552
 553   base::string16 old_name = LookupAppContainer(sid);
 554   if (old_name.empty())
 555     return CreateAppContainer(sid, name);
 556
 557   if (old_name != name)
 558     return SBOX_ERROR_INVALID_APP_CONTAINER;
 559
 560   return SBOX_ALL_OK;
 561 }
 562
 563 ResultCode BrokerServicesBase::UninstallAppContainer(const wchar_t* sid) {
 564   if (base::win::OSInfo::GetInstance()->version() < base::win::VERSION_WIN8)
 565     return SBOX_ERROR_UNSUPPORTED;
 566
 567   base::string16 name = LookupAppContainer(sid);
 568   if (name.empty())
 569     return SBOX_ERROR_INVALID_APP_CONTAINER;
 570
 571   return DeleteAppContainer(sid);
 572 }
 573
 574 }  // namespace sandbox