components/nacl/browser/nacl_browser.cc

   1 // Copyright 2013 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 "components/nacl/browser/nacl_browser.h"
   6
   7 #include "base/command_line.h"
   8 #include "base/files/file_proxy.h"
   9 #include "base/files/file_util.h"
  10 #include "base/message_loop/message_loop.h"
  11 #include "base/metrics/histogram.h"
  12 #include "base/path_service.h"
  13 #include "base/pickle.h"
  14 #include "base/rand_util.h"
  15 #include "base/time/time.h"
  16 #include "base/win/windows_version.h"
  17 #include "build/build_config.h"
  18 #include "content/public/browser/browser_thread.h"
  19 #include "url/gurl.h"
  20
  21 namespace {
  22
  23 // An arbitrary delay to coalesce multiple writes to the cache.
  24 const int kValidationCacheCoalescingTimeMS = 6000;
  25 const char kValidationCacheSequenceName[] = "NaClValidationCache";
  26 const base::FilePath::CharType kValidationCacheFileName[] =
  27     FILE_PATH_LITERAL("nacl_validation_cache.bin");
  28
  29 const bool kValidationCacheEnabledByDefault = true;
  30
  31 // Keep the cache bounded to an arbitrary size.  If it's too small, useful
  32 // entries could be evicted when multiple .nexes are loaded at once.  On the
  33 // other hand, entries are not always claimed (and hence removed), so the size
  34 // of the cache will likely saturate at its maximum size.
  35 // Entries may not be claimed for two main reasons. 1) the NaCl process could
  36 // be killed while it is loading.  2) the trusted NaCl plugin opens files using
  37 // the code path but doesn't resolve them.
  38 // TODO(ncbray) don't cache files that the plugin will not resolve.
  39 const int kFilePathCacheSize = 100;
  40
  41 const base::FilePath::StringType NaClIrtName() {
  42   base::FilePath::StringType irt_name(FILE_PATH_LITERAL("nacl_irt_"));
  43
  44 #if defined(ARCH_CPU_X86_FAMILY)
  45 #if defined(ARCH_CPU_X86_64)
  46   bool is64 = true;
  47 #elif defined(OS_WIN)
  48   bool is64 = (base::win::OSInfo::GetInstance()->wow64_status() ==
  49                base::win::OSInfo::WOW64_ENABLED);
  50 #else
  51   bool is64 = false;
  52 #endif
  53   if (is64)
  54     irt_name.append(FILE_PATH_LITERAL("x86_64"));
  55   else
  56     irt_name.append(FILE_PATH_LITERAL("x86_32"));
  57
  58 #elif defined(ARCH_CPU_ARMEL)
  59   irt_name.append(FILE_PATH_LITERAL("arm"));
  60 #elif defined(ARCH_CPU_MIPSEL)
  61   irt_name.append(FILE_PATH_LITERAL("mips32"));
  62 #else
  63 #error Add support for your architecture to NaCl IRT file selection
  64 #endif
  65   irt_name.append(FILE_PATH_LITERAL(".nexe"));
  66   return irt_name;
  67 }
  68
  69 #if !defined(OS_ANDROID)
  70 bool CheckEnvVar(const char* name, bool default_value) {
  71   bool result = default_value;
  72   const char* var = getenv(name);
  73   if (var && strlen(var) > 0) {
  74     result = var[0] != '0';
  75   }
  76   return result;
  77 }
  78 #endif
  79
  80 void ReadCache(const base::FilePath& filename, std::string* data) {
  81   if (!base::ReadFileToString(filename, data)) {
  82     // Zero-size data used as an in-band error code.
  83     data->clear();
  84   }
  85 }
  86
  87 void WriteCache(const base::FilePath& filename, const Pickle* pickle) {
  88   base::WriteFile(filename, static_cast<const char*>(pickle->data()),
  89                        pickle->size());
  90 }
  91
  92 void RemoveCache(const base::FilePath& filename,
  93                  const base::Closure& callback) {
  94   base::DeleteFile(filename, false);
  95   content::BrowserThread::PostTask(content::BrowserThread::IO, FROM_HERE,
  96                                    callback);
  97 }
  98
  99 void LogCacheQuery(nacl::NaClBrowser::ValidationCacheStatus status) {
 100   UMA_HISTOGRAM_ENUMERATION("NaCl.ValidationCache.Query", status,
 101                             nacl::NaClBrowser::CACHE_MAX);
 102 }
 103
 104 void LogCacheSet(nacl::NaClBrowser::ValidationCacheStatus status) {
 105   // Bucket zero is reserved for future use.
 106   UMA_HISTOGRAM_ENUMERATION("NaCl.ValidationCache.Set", status,
 107                             nacl::NaClBrowser::CACHE_MAX);
 108 }
 109
 110 // Crash throttling parameters.
 111 const size_t kMaxCrashesPerInterval = 3;
 112 const int64 kCrashesIntervalInSeconds = 120;
 113
 114 }  // namespace
 115
 116 namespace nacl {
 117
 118 base::File OpenNaClReadExecImpl(const base::FilePath& file_path,
 119                                 bool is_executable) {
 120   // Get a file descriptor. On Windows, we need 'GENERIC_EXECUTE' in order to
 121   // memory map the executable.
 122   // IMPORTANT: This file descriptor must not have write access - that could
 123   // allow a NaCl inner sandbox escape.
 124   uint32 flags = base::File::FLAG_OPEN | base::File::FLAG_READ;
 125   if (is_executable)
 126     flags |= base::File::FLAG_EXECUTE;  // Windows only flag.
 127   base::File file(file_path, flags);
 128   if (!file.IsValid())
 129     return file.Pass();
 130
 131   // Check that the file does not reference a directory. Returning a descriptor
 132   // to an extension directory could allow an outer sandbox escape. openat(...)
 133   // could be used to traverse into the file system.
 134   base::File::Info file_info;
 135   if (!file.GetInfo(&file_info) || file_info.is_directory)
 136     return base::File();
 137
 138   return file.Pass();
 139 }
 140
 141 NaClBrowser::NaClBrowser()
 142     : irt_filepath_(),
 143       irt_state_(NaClResourceUninitialized),
 144       validation_cache_file_path_(),
 145       validation_cache_is_enabled_(false),
 146       validation_cache_is_modified_(false),
 147       validation_cache_state_(NaClResourceUninitialized),
 148       path_cache_(kFilePathCacheSize),
 149       ok_(true),
 150       weak_factory_(this) {
 151 #if !defined(OS_ANDROID)
 152       validation_cache_is_enabled_ =
 153           CheckEnvVar("NACL_VALIDATION_CACHE",
 154                       kValidationCacheEnabledByDefault);
 155 #endif
 156 }
 157
 158 void NaClBrowser::SetDelegate(NaClBrowserDelegate* delegate) {
 159   NaClBrowser* nacl_browser = NaClBrowser::GetInstance();
 160   nacl_browser->browser_delegate_.reset(delegate);
 161 }
 162
 163 NaClBrowserDelegate* NaClBrowser::GetDelegate() {
 164   // The delegate is not owned by the IO thread.  This accessor method can be
 165   // called from other threads.
 166   DCHECK(GetInstance()->browser_delegate_.get() != NULL);
 167   return GetInstance()->browser_delegate_.get();
 168 }
 169
 170 void NaClBrowser::EarlyStartup() {
 171   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 172   InitIrtFilePath();
 173   InitValidationCacheFilePath();
 174 }
 175
 176 NaClBrowser::~NaClBrowser() {
 177 }
 178
 179 void NaClBrowser::InitIrtFilePath() {
 180   // Allow the IRT library to be overridden via an environment
 181   // variable.  This allows the NaCl/Chromium integration bot to
 182   // specify a newly-built IRT rather than using a prebuilt one
 183   // downloaded via Chromium's DEPS file.  We use the same environment
 184   // variable that the standalone NaCl PPAPI plugin accepts.
 185   const char* irt_path_var = getenv("NACL_IRT_LIBRARY");
 186   if (irt_path_var != NULL) {
 187     base::FilePath::StringType path_string(
 188         irt_path_var, const_cast<const char*>(strchr(irt_path_var, '\0')));
 189     irt_filepath_ = base::FilePath(path_string);
 190   } else {
 191     base::FilePath plugin_dir;
 192     if (!browser_delegate_->GetPluginDirectory(&plugin_dir)) {
 193       DLOG(ERROR) << "Failed to locate the plugins directory, NaCl disabled.";
 194       MarkAsFailed();
 195       return;
 196     }
 197     irt_filepath_ = plugin_dir.Append(NaClIrtName());
 198   }
 199 }
 200
 201 #if defined(OS_WIN)
 202 bool NaClBrowser::GetNaCl64ExePath(base::FilePath* exe_path) {
 203   base::FilePath module_path;
 204   if (!PathService::Get(base::FILE_MODULE, &module_path)) {
 205     LOG(ERROR) << "NaCl process launch failed: could not resolve module";
 206     return false;
 207   }
 208   *exe_path = module_path.DirName().Append(L"nacl64");
 209   return true;
 210 }
 211 #endif
 212
 213 NaClBrowser* NaClBrowser::GetInstance() {
 214   return Singleton<NaClBrowser>::get();
 215 }
 216
 217 bool NaClBrowser::IsReady() const {
 218   return (IsOk() &&
 219           irt_state_ == NaClResourceReady &&
 220           validation_cache_state_ == NaClResourceReady);
 221 }
 222
 223 bool NaClBrowser::IsOk() const {
 224   return ok_;
 225 }
 226
 227 const base::File& NaClBrowser::IrtFile() const {
 228   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 229   CHECK_EQ(irt_state_, NaClResourceReady);
 230   CHECK(irt_file_.IsValid());
 231   return irt_file_;
 232 }
 233
 234 void NaClBrowser::EnsureAllResourcesAvailable() {
 235   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 236   EnsureIrtAvailable();
 237   EnsureValidationCacheAvailable();
 238 }
 239
 240 // Load the IRT async.
 241 void NaClBrowser::EnsureIrtAvailable() {
 242   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 243   if (IsOk() && irt_state_ == NaClResourceUninitialized) {
 244     irt_state_ = NaClResourceRequested;
 245     // TODO(ncbray) use blocking pool.
 246     scoped_ptr<base::FileProxy> file_proxy(new base::FileProxy(
 247         content::BrowserThread::GetMessageLoopProxyForThread(
 248                 content::BrowserThread::FILE).get()));
 249     base::FileProxy* proxy = file_proxy.get();
 250     if (!proxy->CreateOrOpen(irt_filepath_,
 251                              base::File::FLAG_OPEN | base::File::FLAG_READ,
 252                              base::Bind(&NaClBrowser::OnIrtOpened,
 253                                         weak_factory_.GetWeakPtr(),
 254                                         Passed(&file_proxy)))) {
 255       LOG(ERROR) << "Internal error, NaCl disabled.";
 256       MarkAsFailed();
 257     }
 258   }
 259 }
 260
 261 void NaClBrowser::OnIrtOpened(scoped_ptr<base::FileProxy> file_proxy,
 262                               base::File::Error error_code) {
 263   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 264   DCHECK_EQ(irt_state_, NaClResourceRequested);
 265   if (file_proxy->IsValid()) {
 266     irt_file_ = file_proxy->TakeFile();
 267   } else {
 268     LOG(ERROR) << "Failed to open NaCl IRT file \""
 269                << irt_filepath_.LossyDisplayName()
 270                << "\": " << error_code;
 271     MarkAsFailed();
 272   }
 273   irt_state_ = NaClResourceReady;
 274   CheckWaiting();
 275 }
 276
 277 void NaClBrowser::SetProcessGdbDebugStubPort(int process_id, int port) {
 278   gdb_debug_stub_port_map_[process_id] = port;
 279   if (port != kGdbDebugStubPortUnknown &&
 280       !debug_stub_port_listener_.is_null()) {
 281     content::BrowserThread::PostTask(
 282         content::BrowserThread::IO,
 283         FROM_HERE,
 284         base::Bind(debug_stub_port_listener_, port));
 285   }
 286 }
 287
 288 void NaClBrowser::SetGdbDebugStubPortListener(
 289     base::Callback<void(int)> listener) {
 290   debug_stub_port_listener_ = listener;
 291 }
 292
 293 void NaClBrowser::ClearGdbDebugStubPortListener() {
 294   debug_stub_port_listener_.Reset();
 295 }
 296
 297 int NaClBrowser::GetProcessGdbDebugStubPort(int process_id) {
 298   GdbDebugStubPortMap::iterator i = gdb_debug_stub_port_map_.find(process_id);
 299   if (i != gdb_debug_stub_port_map_.end()) {
 300     return i->second;
 301   }
 302   return kGdbDebugStubPortUnused;
 303 }
 304
 305 void NaClBrowser::InitValidationCacheFilePath() {
 306   // Determine where the validation cache resides in the file system.  It
 307   // exists in Chrome's cache directory and is not tied to any specific
 308   // profile.
 309   // Start by finding the user data directory.
 310   base::FilePath user_data_dir;
 311   if (!browser_delegate_->GetUserDirectory(&user_data_dir)) {
 312     RunWithoutValidationCache();
 313     return;
 314   }
 315   // The cache directory may or may not be the user data directory.
 316   base::FilePath cache_file_path;
 317   browser_delegate_->GetCacheDirectory(&cache_file_path);
 318   // Append the base file name to the cache directory.
 319
 320   validation_cache_file_path_ =
 321       cache_file_path.Append(kValidationCacheFileName);
 322 }
 323
 324 void NaClBrowser::EnsureValidationCacheAvailable() {
 325   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 326   if (IsOk() && validation_cache_state_ == NaClResourceUninitialized) {
 327     if (ValidationCacheIsEnabled()) {
 328       validation_cache_state_ = NaClResourceRequested;
 329
 330       // Structure for carrying data between the callbacks.
 331       std::string* data = new std::string();
 332       // We can get away not giving this a sequence ID because this is the first
 333       // task and further file access will not occur until after we get a
 334       // response.
 335       if (!content::BrowserThread::PostBlockingPoolTaskAndReply(
 336               FROM_HERE,
 337               base::Bind(ReadCache, validation_cache_file_path_, data),
 338               base::Bind(&NaClBrowser::OnValidationCacheLoaded,
 339                          weak_factory_.GetWeakPtr(),
 340                          base::Owned(data)))) {
 341         RunWithoutValidationCache();
 342       }
 343     } else {
 344       RunWithoutValidationCache();
 345     }
 346   }
 347 }
 348
 349 void NaClBrowser::OnValidationCacheLoaded(const std::string *data) {
 350   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 351   // Did the cache get cleared before the load completed?  If so, ignore the
 352   // incoming data.
 353   if (validation_cache_state_ == NaClResourceReady)
 354     return;
 355
 356   if (data->size() == 0) {
 357     // No file found.
 358     validation_cache_.Reset();
 359   } else {
 360     Pickle pickle(data->data(), data->size());
 361     validation_cache_.Deserialize(&pickle);
 362   }
 363   validation_cache_state_ = NaClResourceReady;
 364   CheckWaiting();
 365 }
 366
 367 void NaClBrowser::RunWithoutValidationCache() {
 368   // Be paranoid.
 369   validation_cache_.Reset();
 370   validation_cache_is_enabled_ = false;
 371   validation_cache_state_ = NaClResourceReady;
 372   CheckWaiting();
 373 }
 374
 375 void NaClBrowser::CheckWaiting() {
 376   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 377   if (!IsOk() || IsReady()) {
 378     // Queue the waiting tasks into the message loop.  This helps avoid
 379     // re-entrancy problems that could occur if the closure was invoked
 380     // directly.  For example, this could result in use-after-free of the
 381     // process host.
 382     for (std::vector<base::Closure>::iterator iter = waiting_.begin();
 383          iter != waiting_.end(); ++iter) {
 384       base::MessageLoop::current()->PostTask(FROM_HERE, *iter);
 385     }
 386     waiting_.clear();
 387   }
 388 }
 389
 390 void NaClBrowser::MarkAsFailed() {
 391   ok_ = false;
 392   CheckWaiting();
 393 }
 394
 395 void NaClBrowser::WaitForResources(const base::Closure& reply) {
 396   waiting_.push_back(reply);
 397   EnsureAllResourcesAvailable();
 398   CheckWaiting();
 399 }
 400
 401 const base::FilePath& NaClBrowser::GetIrtFilePath() {
 402   return irt_filepath_;
 403 }
 404
 405 void NaClBrowser::PutFilePath(const base::FilePath& path, uint64* file_token_lo,
 406                               uint64* file_token_hi) {
 407   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 408   while (true) {
 409     uint64 file_token[2] = {base::RandUint64(), base::RandUint64()};
 410     // A zero file_token indicates there is no file_token, if we get zero, ask
 411     // for another number.
 412     if (file_token[0] != 0 || file_token[1] != 0) {
 413       // If the file_token is in use, ask for another number.
 414       std::string key(reinterpret_cast<char*>(file_token), sizeof(file_token));
 415       PathCacheType::iterator iter = path_cache_.Peek(key);
 416       if (iter == path_cache_.end()) {
 417         path_cache_.Put(key, path);
 418         *file_token_lo = file_token[0];
 419         *file_token_hi = file_token[1];
 420         break;
 421       }
 422     }
 423   }
 424 }
 425
 426 bool NaClBrowser::GetFilePath(uint64 file_token_lo, uint64 file_token_hi,
 427                               base::FilePath* path) {
 428   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 429   uint64 file_token[2] = {file_token_lo, file_token_hi};
 430   std::string key(reinterpret_cast<char*>(file_token), sizeof(file_token));
 431   PathCacheType::iterator iter = path_cache_.Peek(key);
 432   if (iter == path_cache_.end()) {
 433     *path = base::FilePath(FILE_PATH_LITERAL(""));
 434     return false;
 435   }
 436   *path = iter->second;
 437   path_cache_.Erase(iter);
 438   return true;
 439 }
 440
 441
 442 bool NaClBrowser::QueryKnownToValidate(const std::string& signature,
 443                                        bool off_the_record) {
 444   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 445   if (off_the_record) {
 446     // If we're off the record, don't reorder the main cache.
 447     return validation_cache_.QueryKnownToValidate(signature, false) ||
 448         off_the_record_validation_cache_.QueryKnownToValidate(signature, true);
 449   } else {
 450     bool result = validation_cache_.QueryKnownToValidate(signature, true);
 451     LogCacheQuery(result ? CACHE_HIT : CACHE_MISS);
 452     // Queries can modify the MRU order of the cache.
 453     MarkValidationCacheAsModified();
 454     return result;
 455   }
 456 }
 457
 458 void NaClBrowser::SetKnownToValidate(const std::string& signature,
 459                                      bool off_the_record) {
 460   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 461   if (off_the_record) {
 462     off_the_record_validation_cache_.SetKnownToValidate(signature);
 463   } else {
 464     validation_cache_.SetKnownToValidate(signature);
 465     // The number of sets should be equal to the number of cache misses, minus
 466     // validation failures and successful validations where stubout occurs.
 467     LogCacheSet(CACHE_HIT);
 468     MarkValidationCacheAsModified();
 469   }
 470 }
 471
 472 void NaClBrowser::ClearValidationCache(const base::Closure& callback) {
 473   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 474   // Note: this method may be called before EnsureValidationCacheAvailable has
 475   // been invoked.  In other words, this method may be called before any NaCl
 476   // processes have been created.  This method must succeed and invoke the
 477   // callback in such a case.  If it does not invoke the callback, Chrome's UI
 478   // will hang in that case.
 479   validation_cache_.Reset();
 480   off_the_record_validation_cache_.Reset();
 481
 482   if (validation_cache_file_path_.empty()) {
 483     // Can't figure out what file to remove, but don't drop the callback.
 484     content::BrowserThread::PostTask(content::BrowserThread::IO, FROM_HERE,
 485                                      callback);
 486   } else {
 487     // Delegate the removal of the cache from the filesystem to another thread
 488     // to avoid blocking the IO thread.
 489     // This task is dispatched immediately, not delayed and coalesced, because
 490     // the user interface for cache clearing is likely waiting for the callback.
 491     // In addition, we need to make sure the cache is actually cleared before
 492     // invoking the callback to meet the implicit guarantees of the UI.
 493     content::BrowserThread::PostBlockingPoolSequencedTask(
 494         kValidationCacheSequenceName,
 495         FROM_HERE,
 496         base::Bind(RemoveCache, validation_cache_file_path_, callback));
 497   }
 498
 499   // Make sure any delayed tasks to persist the cache to the filesystem are
 500   // squelched.
 501   validation_cache_is_modified_ = false;
 502
 503   // If the cache is cleared before it is loaded from the filesystem, act as if
 504   // we just loaded an empty cache.
 505   if (validation_cache_state_ != NaClResourceReady) {
 506     validation_cache_state_ = NaClResourceReady;
 507     CheckWaiting();
 508   }
 509 }
 510
 511 void NaClBrowser::MarkValidationCacheAsModified() {
 512   if (!validation_cache_is_modified_) {
 513     // Wait before persisting to disk.  This can coalesce multiple cache
 514     // modifications info a single disk write.
 515     base::MessageLoop::current()->PostDelayedTask(
 516          FROM_HERE,
 517          base::Bind(&NaClBrowser::PersistValidationCache,
 518                     weak_factory_.GetWeakPtr()),
 519          base::TimeDelta::FromMilliseconds(kValidationCacheCoalescingTimeMS));
 520     validation_cache_is_modified_ = true;
 521   }
 522 }
 523
 524 void NaClBrowser::PersistValidationCache() {
 525   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 526   // validation_cache_is_modified_ may be false if the cache was cleared while
 527   // this delayed task was pending.
 528   // validation_cache_file_path_ may be empty if something went wrong during
 529   // initialization.
 530   if (validation_cache_is_modified_ && !validation_cache_file_path_.empty()) {
 531     Pickle* pickle = new Pickle();
 532     validation_cache_.Serialize(pickle);
 533
 534     // Pass the serialized data to another thread to write to disk.  File IO is
 535     // not allowed on the IO thread (which is the thread this method runs on)
 536     // because it can degrade the responsiveness of the browser.
 537     // The task is sequenced so that multiple writes happen in order.
 538     content::BrowserThread::PostBlockingPoolSequencedTask(
 539         kValidationCacheSequenceName,
 540         FROM_HERE,
 541         base::Bind(WriteCache, validation_cache_file_path_,
 542                    base::Owned(pickle)));
 543   }
 544   validation_cache_is_modified_ = false;
 545 }
 546
 547 void NaClBrowser::OnProcessEnd(int process_id) {
 548   gdb_debug_stub_port_map_.erase(process_id);
 549 }
 550
 551 void NaClBrowser::OnProcessCrashed() {
 552   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 553   if (crash_times_.size() == kMaxCrashesPerInterval) {
 554     crash_times_.pop_front();
 555   }
 556   base::Time time = base::Time::Now();
 557   crash_times_.push_back(time);
 558 }
 559
 560 bool NaClBrowser::IsThrottled() {
 561   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
 562   if (crash_times_.size() != kMaxCrashesPerInterval) {
 563     return false;
 564   }
 565   base::TimeDelta delta = base::Time::Now() - crash_times_.front();
 566   return delta.InSeconds() <= kCrashesIntervalInSeconds;
 567 }
 568
 569 }  // namespace nacl