src/chrome/browser/safe_browsing/download_protection_service.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 "chrome/browser/safe_browsing/download_protection_service.h"
   6
   7 #include "base/bind.h"
   8 #include "base/compiler_specific.h"
   9 #include "base/format_macros.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "base/memory/weak_ptr.h"
  12 #include "base/metrics/histogram.h"
  13 #include "base/metrics/sparse_histogram.h"
  14 #include "base/sequenced_task_runner_helpers.h"
  15 #include "base/stl_util.h"
  16 #include "base/strings/string_number_conversions.h"
  17 #include "base/strings/string_util.h"
  18 #include "base/strings/stringprintf.h"
  19 #include "base/threading/sequenced_worker_pool.h"
  20 #include "base/time/time.h"
  21 #include "chrome/browser/safe_browsing/download_feedback_service.h"
  22 #include "chrome/browser/safe_browsing/safe_browsing_service.h"
  23 #include "chrome/browser/safe_browsing/sandboxed_zip_analyzer.h"
  24 #include "chrome/browser/safe_browsing/signature_util.h"
  25 #include "chrome/browser/ui/browser.h"
  26 #include "chrome/browser/ui/browser_list.h"
  27 #include "chrome/common/safe_browsing/csd.pb.h"
  28 #include "chrome/common/safe_browsing/download_protection_util.h"
  29 #include "chrome/common/safe_browsing/zip_analyzer.h"
  30 #include "chrome/common/url_constants.h"
  31 #include "content/public/browser/browser_thread.h"
  32 #include "content/public/browser/download_item.h"
  33 #include "content/public/browser/page_navigator.h"
  34 #include "google_apis/google_api_keys.h"
  35 #include "net/base/escape.h"
  36 #include "net/base/load_flags.h"
  37 #include "net/cert/x509_cert_types.h"
  38 #include "net/cert/x509_certificate.h"
  39 #include "net/http/http_status_code.h"
  40 #include "net/url_request/url_fetcher.h"
  41 #include "net/url_request/url_fetcher_delegate.h"
  42 #include "net/url_request/url_request_context_getter.h"
  43 #include "net/url_request/url_request_status.h"
  44
  45 using content::BrowserThread;
  46
  47 namespace {
  48 static const int64 kDownloadRequestTimeoutMs = 3000;
  49 }  // namespace
  50
  51 namespace safe_browsing {
  52
  53 const char DownloadProtectionService::kDownloadRequestUrl[] =
  54     "https://sb-ssl.google.com/safebrowsing/clientreport/download";
  55
  56 namespace {
  57 ClientDownloadRequest::DownloadType GetDownloadType(
  58     const base::FilePath& file) {
  59   DCHECK(download_protection_util::IsBinaryFile(file));
  60   if (file.MatchesExtension(FILE_PATH_LITERAL(".apk")))
  61     return ClientDownloadRequest::ANDROID_APK;
  62   else if (file.MatchesExtension(FILE_PATH_LITERAL(".crx")))
  63     return ClientDownloadRequest::CHROME_EXTENSION;
  64   // For zip files, we use the ZIPPED_EXECUTABLE type since we will only send
  65   // the pingback if we find an executable inside the zip archive.
  66   else if (file.MatchesExtension(FILE_PATH_LITERAL(".zip")))
  67     return ClientDownloadRequest::ZIPPED_EXECUTABLE;
  68   return ClientDownloadRequest::WIN_EXECUTABLE;
  69 }
  70
  71 // List of extensions for which we track some UMA stats.
  72 enum MaliciousExtensionType {
  73   EXTENSION_EXE,
  74   EXTENSION_MSI,
  75   EXTENSION_CAB,
  76   EXTENSION_SYS,
  77   EXTENSION_SCR,
  78   EXTENSION_DRV,
  79   EXTENSION_BAT,
  80   EXTENSION_ZIP,
  81   EXTENSION_RAR,
  82   EXTENSION_DLL,
  83   EXTENSION_PIF,
  84   EXTENSION_COM,
  85   EXTENSION_JAR,
  86   EXTENSION_CLASS,
  87   EXTENSION_PDF,
  88   EXTENSION_VB,
  89   EXTENSION_REG,
  90   EXTENSION_GRP,
  91   EXTENSION_OTHER,  // Groups all other extensions into one bucket.
  92   EXTENSION_CRX,
  93   EXTENSION_APK,
  94   EXTENSION_MAX,
  95 };
  96
  97 MaliciousExtensionType GetExtensionType(const base::FilePath& f) {
  98   if (f.MatchesExtension(FILE_PATH_LITERAL(".exe"))) return EXTENSION_EXE;
  99   if (f.MatchesExtension(FILE_PATH_LITERAL(".msi"))) return EXTENSION_MSI;
 100   if (f.MatchesExtension(FILE_PATH_LITERAL(".cab"))) return EXTENSION_CAB;
 101   if (f.MatchesExtension(FILE_PATH_LITERAL(".sys"))) return EXTENSION_SYS;
 102   if (f.MatchesExtension(FILE_PATH_LITERAL(".scr"))) return EXTENSION_SCR;
 103   if (f.MatchesExtension(FILE_PATH_LITERAL(".drv"))) return EXTENSION_DRV;
 104   if (f.MatchesExtension(FILE_PATH_LITERAL(".bat"))) return EXTENSION_BAT;
 105   if (f.MatchesExtension(FILE_PATH_LITERAL(".zip"))) return EXTENSION_ZIP;
 106   if (f.MatchesExtension(FILE_PATH_LITERAL(".rar"))) return EXTENSION_RAR;
 107   if (f.MatchesExtension(FILE_PATH_LITERAL(".dll"))) return EXTENSION_DLL;
 108   if (f.MatchesExtension(FILE_PATH_LITERAL(".pif"))) return EXTENSION_PIF;
 109   if (f.MatchesExtension(FILE_PATH_LITERAL(".com"))) return EXTENSION_COM;
 110   if (f.MatchesExtension(FILE_PATH_LITERAL(".jar"))) return EXTENSION_JAR;
 111   if (f.MatchesExtension(FILE_PATH_LITERAL(".class"))) return EXTENSION_CLASS;
 112   if (f.MatchesExtension(FILE_PATH_LITERAL(".pdf"))) return EXTENSION_PDF;
 113   if (f.MatchesExtension(FILE_PATH_LITERAL(".vb"))) return EXTENSION_VB;
 114   if (f.MatchesExtension(FILE_PATH_LITERAL(".reg"))) return EXTENSION_REG;
 115   if (f.MatchesExtension(FILE_PATH_LITERAL(".grp"))) return EXTENSION_GRP;
 116   if (f.MatchesExtension(FILE_PATH_LITERAL(".crx"))) return EXTENSION_CRX;
 117   if (f.MatchesExtension(FILE_PATH_LITERAL(".apk"))) return EXTENSION_APK;
 118   return EXTENSION_OTHER;
 119 }
 120
 121 void RecordFileExtensionType(const base::FilePath& file) {
 122   UMA_HISTOGRAM_ENUMERATION("SBClientDownload.DownloadExtensions",
 123                             GetExtensionType(file),
 124                             EXTENSION_MAX);
 125 }
 126
 127 // Enumerate for histogramming purposes.
 128 // DO NOT CHANGE THE ORDERING OF THESE VALUES (different histogram data will
 129 // be mixed together based on their values).
 130 enum SBStatsType {
 131   DOWNLOAD_URL_CHECKS_TOTAL,
 132   DOWNLOAD_URL_CHECKS_CANCELED,
 133   DOWNLOAD_URL_CHECKS_MALWARE,
 134
 135   DOWNLOAD_HASH_CHECKS_TOTAL,
 136   DOWNLOAD_HASH_CHECKS_MALWARE,
 137
 138   // Memory space for histograms is determined by the max.
 139   // ALWAYS ADD NEW VALUES BEFORE THIS ONE.
 140   DOWNLOAD_CHECKS_MAX
 141 };
 142 }  // namespace
 143
 144 // Parent SafeBrowsing::Client class used to lookup the bad binary
 145 // URL and digest list.  There are two sub-classes (one for each list).
 146 class DownloadSBClient
 147     : public SafeBrowsingDatabaseManager::Client,
 148       public base::RefCountedThreadSafe<DownloadSBClient> {
 149  public:
 150   DownloadSBClient(
 151       const content::DownloadItem& item,
 152       const DownloadProtectionService::CheckDownloadCallback& callback,
 153       const scoped_refptr<SafeBrowsingUIManager>& ui_manager,
 154       SBStatsType total_type,
 155       SBStatsType dangerous_type)
 156       : sha256_hash_(item.GetHash()),
 157         url_chain_(item.GetUrlChain()),
 158         referrer_url_(item.GetReferrerUrl()),
 159         callback_(callback),
 160         ui_manager_(ui_manager),
 161         start_time_(base::TimeTicks::Now()),
 162         total_type_(total_type),
 163         dangerous_type_(dangerous_type) {}
 164
 165   virtual void StartCheck() = 0;
 166   virtual bool IsDangerous(SBThreatType threat_type) const = 0;
 167
 168  protected:
 169   friend class base::RefCountedThreadSafe<DownloadSBClient>;
 170   virtual ~DownloadSBClient() {}
 171
 172   void CheckDone(SBThreatType threat_type) {
 173     DownloadProtectionService::DownloadCheckResult result =
 174         IsDangerous(threat_type) ?
 175         DownloadProtectionService::DANGEROUS :
 176         DownloadProtectionService::SAFE;
 177     BrowserThread::PostTask(BrowserThread::UI,
 178                             FROM_HERE,
 179                             base::Bind(callback_, result));
 180     UpdateDownloadCheckStats(total_type_);
 181     if (threat_type != SB_THREAT_TYPE_SAFE) {
 182       UpdateDownloadCheckStats(dangerous_type_);
 183       BrowserThread::PostTask(
 184           BrowserThread::UI,
 185           FROM_HERE,
 186           base::Bind(&DownloadSBClient::ReportMalware,
 187                      this, threat_type));
 188     }
 189   }
 190
 191   void ReportMalware(SBThreatType threat_type) {
 192     std::string post_data;
 193     if (!sha256_hash_.empty())
 194       post_data += base::HexEncode(sha256_hash_.data(),
 195                                    sha256_hash_.size()) + "\n";
 196     for (size_t i = 0; i < url_chain_.size(); ++i) {
 197       post_data += url_chain_[i].spec() + "\n";
 198     }
 199     ui_manager_->ReportSafeBrowsingHit(
 200         url_chain_.back(),  // malicious_url
 201         url_chain_.front(), // page_url
 202         referrer_url_,
 203         true,  // is_subresource
 204         threat_type,
 205         post_data);
 206   }
 207
 208   void UpdateDownloadCheckStats(SBStatsType stat_type) {
 209     UMA_HISTOGRAM_ENUMERATION("SB2.DownloadChecks",
 210                               stat_type,
 211                               DOWNLOAD_CHECKS_MAX);
 212   }
 213
 214   std::string sha256_hash_;
 215   std::vector<GURL> url_chain_;
 216   GURL referrer_url_;
 217   DownloadProtectionService::CheckDownloadCallback callback_;
 218   scoped_refptr<SafeBrowsingUIManager> ui_manager_;
 219   base::TimeTicks start_time_;
 220
 221  private:
 222   const SBStatsType total_type_;
 223   const SBStatsType dangerous_type_;
 224
 225   DISALLOW_COPY_AND_ASSIGN(DownloadSBClient);
 226 };
 227
 228 class DownloadUrlSBClient : public DownloadSBClient {
 229  public:
 230   DownloadUrlSBClient(
 231       const content::DownloadItem& item,
 232       const DownloadProtectionService::CheckDownloadCallback& callback,
 233       const scoped_refptr<SafeBrowsingUIManager>& ui_manager,
 234       const scoped_refptr<SafeBrowsingDatabaseManager>& database_manager)
 235       : DownloadSBClient(item, callback, ui_manager,
 236                          DOWNLOAD_URL_CHECKS_TOTAL,
 237                          DOWNLOAD_URL_CHECKS_MALWARE),
 238         database_manager_(database_manager) { }
 239
 240   virtual void StartCheck() OVERRIDE {
 241     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 242     if (!database_manager_.get() ||
 243         database_manager_->CheckDownloadUrl(url_chain_, this)) {
 244       CheckDone(SB_THREAT_TYPE_SAFE);
 245     } else {
 246       AddRef();  // SafeBrowsingService takes a pointer not a scoped_refptr.
 247     }
 248   }
 249
 250   virtual bool IsDangerous(SBThreatType threat_type) const OVERRIDE {
 251     return threat_type == SB_THREAT_TYPE_BINARY_MALWARE_URL;
 252   }
 253
 254   virtual void OnCheckDownloadUrlResult(const std::vector<GURL>& url_chain,
 255                                         SBThreatType threat_type) OVERRIDE {
 256     CheckDone(threat_type);
 257     UMA_HISTOGRAM_TIMES("SB2.DownloadUrlCheckDuration",
 258                         base::TimeTicks::Now() - start_time_);
 259     Release();
 260   }
 261
 262  protected:
 263   virtual ~DownloadUrlSBClient() {}
 264
 265  private:
 266   scoped_refptr<SafeBrowsingDatabaseManager> database_manager_;
 267
 268   DISALLOW_COPY_AND_ASSIGN(DownloadUrlSBClient);
 269 };
 270
 271 class DownloadProtectionService::CheckClientDownloadRequest
 272     : public base::RefCountedThreadSafe<
 273           DownloadProtectionService::CheckClientDownloadRequest,
 274           BrowserThread::DeleteOnUIThread>,
 275       public net::URLFetcherDelegate,
 276       public content::DownloadItem::Observer {
 277  public:
 278   CheckClientDownloadRequest(
 279       content::DownloadItem* item,
 280       const CheckDownloadCallback& callback,
 281       DownloadProtectionService* service,
 282       const scoped_refptr<SafeBrowsingDatabaseManager>& database_manager,
 283       SignatureUtil* signature_util)
 284       : item_(item),
 285         url_chain_(item->GetUrlChain()),
 286         referrer_url_(item->GetReferrerUrl()),
 287         zipped_executable_(false),
 288         callback_(callback),
 289         service_(service),
 290         signature_util_(signature_util),
 291         database_manager_(database_manager),
 292         pingback_enabled_(service_->enabled()),
 293         finished_(false),
 294         type_(ClientDownloadRequest::WIN_EXECUTABLE),
 295         weakptr_factory_(this),
 296         start_time_(base::TimeTicks::Now()) {
 297     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 298     item_->AddObserver(this);
 299   }
 300
 301   void Start() {
 302     VLOG(2) << "Starting SafeBrowsing download check for: "
 303             << item_->DebugString(true);
 304     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 305     // TODO(noelutz): implement some cache to make sure we don't issue the same
 306     // request over and over again if a user downloads the same binary multiple
 307     // times.
 308     DownloadCheckResultReason reason = REASON_MAX;
 309     if (!IsSupportedDownload(
 310         *item_, item_->GetTargetFilePath(), &reason, &type_)) {
 311       switch (reason) {
 312         case REASON_EMPTY_URL_CHAIN:
 313         case REASON_INVALID_URL:
 314           PostFinishTask(SAFE, reason);
 315           return;
 316
 317         case REASON_NOT_BINARY_FILE:
 318           RecordFileExtensionType(item_->GetTargetFilePath());
 319           PostFinishTask(SAFE, reason);
 320           return;
 321
 322         default:
 323           // We only expect the reasons explicitly handled above.
 324           NOTREACHED();
 325       }
 326     }
 327     RecordFileExtensionType(item_->GetTargetFilePath());
 328
 329     // Compute features from the file contents. Note that we record histograms
 330     // based on the result, so this runs regardless of whether the pingbacks
 331     // are enabled.
 332     if (item_->GetTargetFilePath().MatchesExtension(
 333         FILE_PATH_LITERAL(".zip"))) {
 334       StartExtractZipFeatures();
 335     } else {
 336       DCHECK(!download_protection_util::IsArchiveFile(
 337           item_->GetTargetFilePath()));
 338       StartExtractSignatureFeatures();
 339     }
 340   }
 341
 342   // Start a timeout to cancel the request if it takes too long.
 343   // This should only be called after we have finished accessing the file.
 344   void StartTimeout() {
 345     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 346     if (!service_) {
 347       // Request has already been cancelled.
 348       return;
 349     }
 350     BrowserThread::PostDelayedTask(
 351         BrowserThread::UI,
 352         FROM_HERE,
 353         base::Bind(&CheckClientDownloadRequest::Cancel,
 354                    weakptr_factory_.GetWeakPtr()),
 355         base::TimeDelta::FromMilliseconds(
 356             service_->download_request_timeout_ms()));
 357   }
 358
 359   // Canceling a request will cause us to always report the result as SAFE
 360   // unless a pending request is about to call FinishRequest.
 361   void Cancel() {
 362     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 363     if (fetcher_.get()) {
 364       // The DownloadProtectionService is going to release its reference, so we
 365       // might be destroyed before the URLFetcher completes.  Cancel the
 366       // fetcher so it does not try to invoke OnURLFetchComplete.
 367       fetcher_.reset();
 368     }
 369     // Note: If there is no fetcher, then some callback is still holding a
 370     // reference to this object.  We'll eventually wind up in some method on
 371     // the UI thread that will call FinishRequest() again.  If FinishRequest()
 372     // is called a second time, it will be a no-op.
 373     FinishRequest(SAFE, REASON_REQUEST_CANCELED);
 374     // Calling FinishRequest might delete this object, we may be deleted by
 375     // this point.
 376   }
 377
 378   // content::DownloadItem::Observer implementation.
 379   virtual void OnDownloadDestroyed(content::DownloadItem* download) OVERRIDE {
 380     Cancel();
 381     DCHECK(item_ == NULL);
 382   }
 383
 384   // From the net::URLFetcherDelegate interface.
 385   virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE {
 386     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 387     DCHECK_EQ(source, fetcher_.get());
 388     VLOG(2) << "Received a response for URL: "
 389             << item_->GetUrlChain().back() << ": success="
 390             << source->GetStatus().is_success() << " response_code="
 391             << source->GetResponseCode();
 392     if (source->GetStatus().is_success()) {
 393       UMA_HISTOGRAM_SPARSE_SLOWLY(
 394           "SBClientDownload.DownloadRequestResponseCode",
 395           source->GetResponseCode());
 396     }
 397     UMA_HISTOGRAM_SPARSE_SLOWLY(
 398         "SBClientDownload.DownloadRequestNetError",
 399         -source->GetStatus().error());
 400     DownloadCheckResultReason reason = REASON_SERVER_PING_FAILED;
 401     DownloadCheckResult result = SAFE;
 402     if (source->GetStatus().is_success() &&
 403         net::HTTP_OK == source->GetResponseCode()) {
 404       ClientDownloadResponse response;
 405       std::string data;
 406       bool got_data = source->GetResponseAsString(&data);
 407       DCHECK(got_data);
 408       if (!response.ParseFromString(data)) {
 409         reason = REASON_INVALID_RESPONSE_PROTO;
 410       } else if (response.verdict() == ClientDownloadResponse::SAFE) {
 411         reason = REASON_DOWNLOAD_SAFE;
 412       } else if (service_ && !service_->IsSupportedDownload(
 413           *item_, item_->GetTargetFilePath())) {
 414         // The client of the download protection service assumes that we don't
 415         // support this download so we cannot return any other verdict than
 416         // SAFE even if the server says it's dangerous to download this file.
 417         // Note: if service_ is NULL we already cancelled the request and
 418         // returned SAFE.
 419         reason = REASON_DOWNLOAD_NOT_SUPPORTED;
 420       } else if (response.verdict() == ClientDownloadResponse::DANGEROUS) {
 421         reason = REASON_DOWNLOAD_DANGEROUS;
 422         result = DANGEROUS;
 423       } else if (response.verdict() == ClientDownloadResponse::UNCOMMON) {
 424         reason = REASON_DOWNLOAD_UNCOMMON;
 425         result = UNCOMMON;
 426       } else if (response.verdict() == ClientDownloadResponse::DANGEROUS_HOST) {
 427         reason = REASON_DOWNLOAD_DANGEROUS_HOST;
 428         result = DANGEROUS_HOST;
 429       } else if (
 430           response.verdict() == ClientDownloadResponse::POTENTIALLY_UNWANTED) {
 431         reason = REASON_DOWNLOAD_POTENTIALLY_UNWANTED;
 432         result = POTENTIALLY_UNWANTED;
 433       } else {
 434         LOG(DFATAL) << "Unknown download response verdict: "
 435                     << response.verdict();
 436         reason = REASON_INVALID_RESPONSE_VERDICT;
 437       }
 438       DownloadFeedbackService::MaybeStorePingsForDownload(
 439           result, item_, client_download_request_data_, data);
 440     }
 441     // We don't need the fetcher anymore.
 442     fetcher_.reset();
 443     UMA_HISTOGRAM_TIMES("SBClientDownload.DownloadRequestDuration",
 444                         base::TimeTicks::Now() - start_time_);
 445     FinishRequest(result, reason);
 446   }
 447
 448   static bool IsSupportedDownload(const content::DownloadItem& item,
 449                                   const base::FilePath& target_path,
 450                                   DownloadCheckResultReason* reason,
 451                                   ClientDownloadRequest::DownloadType* type) {
 452     if (item.GetUrlChain().empty()) {
 453       *reason = REASON_EMPTY_URL_CHAIN;
 454       return false;
 455     }
 456     const GURL& final_url = item.GetUrlChain().back();
 457     if (!final_url.is_valid() || final_url.is_empty() ||
 458         !final_url.IsStandard() || final_url.SchemeIsFile()) {
 459       *reason = REASON_INVALID_URL;
 460       return false;
 461     }
 462     if (!download_protection_util::IsBinaryFile(target_path)) {
 463       *reason = REASON_NOT_BINARY_FILE;
 464       return false;
 465     }
 466     *type = GetDownloadType(target_path);
 467     return true;
 468   }
 469
 470  private:
 471   friend struct BrowserThread::DeleteOnThread<BrowserThread::UI>;
 472   friend class base::DeleteHelper<CheckClientDownloadRequest>;
 473
 474   virtual ~CheckClientDownloadRequest() {
 475     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 476     DCHECK(item_ == NULL);
 477   }
 478
 479   void OnFileFeatureExtractionDone() {
 480     // This can run in any thread, since it just posts more messages.
 481
 482     // TODO(noelutz): DownloadInfo should also contain the IP address of
 483     // every URL in the redirect chain.  We also should check whether the
 484     // download URL is hosted on the internal network.
 485     BrowserThread::PostTask(
 486         BrowserThread::IO,
 487         FROM_HERE,
 488         base::Bind(&CheckClientDownloadRequest::CheckWhitelists, this));
 489
 490     // We wait until after the file checks finish to start the timeout, as
 491     // windows can cause permissions errors if the timeout fired while we were
 492     // checking the file signature and we tried to complete the download.
 493     BrowserThread::PostTask(
 494         BrowserThread::UI,
 495         FROM_HERE,
 496         base::Bind(&CheckClientDownloadRequest::StartTimeout, this));
 497   }
 498
 499   void StartExtractSignatureFeatures() {
 500     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 501     DCHECK(item_);  // Called directly from Start(), item should still exist.
 502     // Since we do blocking I/O, offload this to a worker thread.
 503     // The task does not need to block shutdown.
 504     BrowserThread::GetBlockingPool()->PostWorkerTaskWithShutdownBehavior(
 505         FROM_HERE,
 506         base::Bind(&CheckClientDownloadRequest::ExtractSignatureFeatures,
 507                    this, item_->GetFullPath()),
 508         base::SequencedWorkerPool::CONTINUE_ON_SHUTDOWN);
 509   }
 510
 511   void ExtractSignatureFeatures(const base::FilePath& file_path) {
 512     base::TimeTicks start_time = base::TimeTicks::Now();
 513     signature_util_->CheckSignature(file_path, &signature_info_);
 514     bool is_signed = (signature_info_.certificate_chain_size() > 0);
 515     if (is_signed) {
 516       VLOG(2) << "Downloaded a signed binary: " << file_path.value();
 517     } else {
 518       VLOG(2) << "Downloaded an unsigned binary: "
 519               << file_path.value();
 520     }
 521     UMA_HISTOGRAM_BOOLEAN("SBClientDownload.SignedBinaryDownload", is_signed);
 522     UMA_HISTOGRAM_TIMES("SBClientDownload.ExtractSignatureFeaturesTime",
 523                         base::TimeTicks::Now() - start_time);
 524
 525     OnFileFeatureExtractionDone();
 526   }
 527
 528   void StartExtractZipFeatures() {
 529     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 530     DCHECK(item_);  // Called directly from Start(), item should still exist.
 531     zip_analysis_start_time_ = base::TimeTicks::Now();
 532     // We give the zip analyzer a weak pointer to this object.  Since the
 533     // analyzer is refcounted, it might outlive the request.
 534     analyzer_ = new SandboxedZipAnalyzer(
 535         item_->GetFullPath(),
 536         base::Bind(&CheckClientDownloadRequest::OnZipAnalysisFinished,
 537                    weakptr_factory_.GetWeakPtr()));
 538     analyzer_->Start();
 539   }
 540
 541   void OnZipAnalysisFinished(const zip_analyzer::Results& results) {
 542     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 543     if (!service_)
 544       return;
 545     if (results.success) {
 546       zipped_executable_ = results.has_executable;
 547       VLOG(1) << "Zip analysis finished for " << item_->GetFullPath().value()
 548               << ", has_executable=" << results.has_executable
 549               << " has_archive=" << results.has_archive;
 550     } else {
 551       VLOG(1) << "Zip analysis failed for " << item_->GetFullPath().value();
 552     }
 553     UMA_HISTOGRAM_BOOLEAN("SBClientDownload.ZipFileHasExecutable",
 554                           zipped_executable_);
 555     UMA_HISTOGRAM_BOOLEAN("SBClientDownload.ZipFileHasArchiveButNoExecutable",
 556                           results.has_archive && !zipped_executable_);
 557     UMA_HISTOGRAM_TIMES("SBClientDownload.ExtractZipFeaturesTime",
 558                         base::TimeTicks::Now() - zip_analysis_start_time_);
 559
 560     if (!zipped_executable_) {
 561       PostFinishTask(SAFE, REASON_ARCHIVE_WITHOUT_BINARIES);
 562       return;
 563     }
 564     OnFileFeatureExtractionDone();
 565   }
 566
 567   void CheckWhitelists() {
 568     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 569     DownloadCheckResultReason reason = REASON_MAX;
 570     if (!database_manager_.get()) {
 571       reason = REASON_SB_DISABLED;
 572     } else {
 573       for (size_t i = 0; i < url_chain_.size(); ++i) {
 574         const GURL& url = url_chain_[i];
 575         if (url.is_valid() &&
 576             database_manager_->MatchDownloadWhitelistUrl(url)) {
 577           VLOG(2) << url << " is on the download whitelist.";
 578           reason = REASON_WHITELISTED_URL;
 579           break;
 580         }
 581       }
 582       if (referrer_url_.is_valid() && reason == REASON_MAX &&
 583           database_manager_->MatchDownloadWhitelistUrl(
 584               referrer_url_)) {
 585         VLOG(2) << "Referrer url " << referrer_url_
 586                 << " is on the download whitelist.";
 587         reason = REASON_WHITELISTED_REFERRER;
 588       }
 589       if (reason != REASON_MAX || signature_info_.trusted()) {
 590         UMA_HISTOGRAM_COUNTS("SBClientDownload.SignedOrWhitelistedDownload", 1);
 591       }
 592     }
 593     if (reason == REASON_MAX && signature_info_.trusted()) {
 594       for (int i = 0; i < signature_info_.certificate_chain_size(); ++i) {
 595         if (CertificateChainIsWhitelisted(
 596                 signature_info_.certificate_chain(i))) {
 597           reason = REASON_TRUSTED_EXECUTABLE;
 598           break;
 599         }
 600       }
 601     }
 602     if (reason != REASON_MAX) {
 603       PostFinishTask(SAFE, reason);
 604     } else if (!pingback_enabled_) {
 605       PostFinishTask(SAFE, REASON_PING_DISABLED);
 606     } else {
 607       // Currently, the UI only works on Windows so we don't even bother
 608       // with pinging the server if we're not on Windows.  TODO(noelutz):
 609       // change this code once the UI is done for Linux and Mac.
 610 #if defined(OS_WIN)
 611       // The URLFetcher is owned by the UI thread, so post a message to
 612       // start the pingback.
 613       BrowserThread::PostTask(
 614           BrowserThread::UI,
 615           FROM_HERE,
 616           base::Bind(&CheckClientDownloadRequest::SendRequest, this));
 617 #else
 618       PostFinishTask(SAFE, REASON_OS_NOT_SUPPORTED);
 619 #endif
 620     }
 621   }
 622
 623   void SendRequest() {
 624     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 625
 626     // This is our last chance to check whether the request has been canceled
 627     // before sending it.
 628     if (!service_)
 629       return;
 630
 631     ClientDownloadRequest request;
 632     request.set_url(item_->GetUrlChain().back().spec());
 633     request.mutable_digests()->set_sha256(item_->GetHash());
 634     request.set_length(item_->GetReceivedBytes());
 635     for (size_t i = 0; i < item_->GetUrlChain().size(); ++i) {
 636       ClientDownloadRequest::Resource* resource = request.add_resources();
 637       resource->set_url(item_->GetUrlChain()[i].spec());
 638       if (i == item_->GetUrlChain().size() - 1) {
 639         // The last URL in the chain is the download URL.
 640         resource->set_type(ClientDownloadRequest::DOWNLOAD_URL);
 641         resource->set_referrer(item_->GetReferrerUrl().spec());
 642         if (!item_->GetRemoteAddress().empty()) {
 643           resource->set_remote_ip(item_->GetRemoteAddress());
 644         }
 645       } else {
 646         resource->set_type(ClientDownloadRequest::DOWNLOAD_REDIRECT);
 647       }
 648       // TODO(noelutz): fill out the remote IP addresses.
 649     }
 650     request.set_user_initiated(item_->HasUserGesture());
 651     request.set_file_basename(
 652         item_->GetTargetFilePath().BaseName().AsUTF8Unsafe());
 653     request.set_download_type(type_);
 654     request.mutable_signature()->CopyFrom(signature_info_);
 655     if (!request.SerializeToString(&client_download_request_data_)) {
 656       FinishRequest(SAFE, REASON_INVALID_REQUEST_PROTO);
 657       return;
 658     }
 659
 660     VLOG(2) << "Sending a request for URL: "
 661             << item_->GetUrlChain().back();
 662     fetcher_.reset(net::URLFetcher::Create(0 /* ID used for testing */,
 663                                            GetDownloadRequestUrl(),
 664                                            net::URLFetcher::POST,
 665                                            this));
 666     fetcher_->SetLoadFlags(net::LOAD_DISABLE_CACHE);
 667     fetcher_->SetAutomaticallyRetryOn5xx(false);  // Don't retry on error.
 668     fetcher_->SetRequestContext(service_->request_context_getter_.get());
 669     fetcher_->SetUploadData("application/octet-stream",
 670                             client_download_request_data_);
 671     UMA_HISTOGRAM_COUNTS("SBClientDownload.DownloadRequestPayloadSize",
 672                          client_download_request_data_.size());
 673     fetcher_->Start();
 674   }
 675
 676   void PostFinishTask(DownloadCheckResult result,
 677                       DownloadCheckResultReason reason) {
 678     BrowserThread::PostTask(
 679         BrowserThread::UI,
 680         FROM_HERE,
 681         base::Bind(&CheckClientDownloadRequest::FinishRequest, this, result,
 682                    reason));
 683   }
 684
 685   void FinishRequest(DownloadCheckResult result,
 686                      DownloadCheckResultReason reason) {
 687     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 688     if (finished_) {
 689       return;
 690     }
 691     finished_ = true;
 692     // Ensure the timeout task is cancelled while we still have a non-zero
 693     // refcount. (crbug.com/240449)
 694     weakptr_factory_.InvalidateWeakPtrs();
 695     if (service_) {
 696       VLOG(2) << "SafeBrowsing download verdict for: "
 697               << item_->DebugString(true) << " verdict:" << reason;
 698       UMA_HISTOGRAM_ENUMERATION("SBClientDownload.CheckDownloadStats",
 699                                 reason,
 700                                 REASON_MAX);
 701       callback_.Run(result);
 702       item_->RemoveObserver(this);
 703       item_ = NULL;
 704       DownloadProtectionService* service = service_;
 705       service_ = NULL;
 706       service->RequestFinished(this);
 707       // DownloadProtectionService::RequestFinished will decrement our refcount,
 708       // so we may be deleted now.
 709     } else {
 710       callback_.Run(SAFE);
 711     }
 712   }
 713
 714   bool CertificateChainIsWhitelisted(
 715       const ClientDownloadRequest_CertificateChain& chain) {
 716     DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 717     if (chain.element_size() < 2) {
 718       // We need to have both a signing certificate and its issuer certificate
 719       // present to construct a whitelist entry.
 720       return false;
 721     }
 722     scoped_refptr<net::X509Certificate> cert =
 723         net::X509Certificate::CreateFromBytes(
 724             chain.element(0).certificate().data(),
 725             chain.element(0).certificate().size());
 726     if (!cert.get()) {
 727       return false;
 728     }
 729
 730     for (int i = 1; i < chain.element_size(); ++i) {
 731       scoped_refptr<net::X509Certificate> issuer =
 732           net::X509Certificate::CreateFromBytes(
 733               chain.element(i).certificate().data(),
 734               chain.element(i).certificate().size());
 735       if (!issuer.get()) {
 736         return false;
 737       }
 738       std::vector<std::string> whitelist_strings;
 739       DownloadProtectionService::GetCertificateWhitelistStrings(
 740           *cert.get(), *issuer.get(), &whitelist_strings);
 741       for (size_t j = 0; j < whitelist_strings.size(); ++j) {
 742         if (database_manager_->MatchDownloadWhitelistString(
 743                 whitelist_strings[j])) {
 744           VLOG(2) << "Certificate matched whitelist, cert="
 745                   << cert->subject().GetDisplayName()
 746                   << " issuer=" << issuer->subject().GetDisplayName();
 747           return true;
 748         }
 749       }
 750       cert = issuer;
 751     }
 752     return false;
 753   }
 754
 755   // The DownloadItem we are checking. Will be NULL if the request has been
 756   // canceled. Must be accessed only on UI thread.
 757   content::DownloadItem* item_;
 758   // Copies of data from |item_| for access on other threads.
 759   std::vector<GURL> url_chain_;
 760   GURL referrer_url_;
 761
 762   bool zipped_executable_;
 763   ClientDownloadRequest_SignatureInfo signature_info_;
 764   CheckDownloadCallback callback_;
 765   // Will be NULL if the request has been canceled.
 766   DownloadProtectionService* service_;
 767   scoped_refptr<SignatureUtil> signature_util_;
 768   scoped_refptr<SafeBrowsingDatabaseManager> database_manager_;
 769   const bool pingback_enabled_;
 770   scoped_ptr<net::URLFetcher> fetcher_;
 771   scoped_refptr<SandboxedZipAnalyzer> analyzer_;
 772   base::TimeTicks zip_analysis_start_time_;
 773   bool finished_;
 774   ClientDownloadRequest::DownloadType type_;
 775   std::string client_download_request_data_;
 776   base::WeakPtrFactory<CheckClientDownloadRequest> weakptr_factory_;
 777   base::TimeTicks start_time_;  // Used for stats.
 778
 779   DISALLOW_COPY_AND_ASSIGN(CheckClientDownloadRequest);
 780 };
 781
 782 DownloadProtectionService::DownloadProtectionService(
 783     SafeBrowsingService* sb_service,
 784     net::URLRequestContextGetter* request_context_getter)
 785     : request_context_getter_(request_context_getter),
 786       enabled_(false),
 787       signature_util_(new SignatureUtil()),
 788       download_request_timeout_ms_(kDownloadRequestTimeoutMs),
 789       feedback_service_(new DownloadFeedbackService(
 790           request_context_getter, BrowserThread::GetBlockingPool())) {
 791
 792   if (sb_service) {
 793     ui_manager_ = sb_service->ui_manager();
 794     database_manager_ = sb_service->database_manager();
 795   }
 796 }
 797
 798 DownloadProtectionService::~DownloadProtectionService() {
 799   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 800   CancelPendingRequests();
 801 }
 802
 803 void DownloadProtectionService::SetEnabled(bool enabled) {
 804   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 805   if (enabled == enabled_) {
 806     return;
 807   }
 808   enabled_ = enabled;
 809   if (!enabled_) {
 810     CancelPendingRequests();
 811   }
 812 }
 813
 814 void DownloadProtectionService::CheckClientDownload(
 815     content::DownloadItem* item,
 816     const CheckDownloadCallback& callback) {
 817   scoped_refptr<CheckClientDownloadRequest> request(
 818       new CheckClientDownloadRequest(item, callback, this,
 819                                      database_manager_, signature_util_.get()));
 820   download_requests_.insert(request);
 821   request->Start();
 822 }
 823
 824 void DownloadProtectionService::CheckDownloadUrl(
 825     const content::DownloadItem& item,
 826     const CheckDownloadCallback& callback) {
 827   DCHECK(!item.GetUrlChain().empty());
 828   scoped_refptr<DownloadUrlSBClient> client(
 829       new DownloadUrlSBClient(item, callback, ui_manager_, database_manager_));
 830   // The client will release itself once it is done.
 831   BrowserThread::PostTask(
 832         BrowserThread::IO,
 833         FROM_HERE,
 834         base::Bind(&DownloadUrlSBClient::StartCheck, client));
 835 }
 836
 837 bool DownloadProtectionService::IsSupportedDownload(
 838     const content::DownloadItem& item,
 839     const base::FilePath& target_path) const {
 840   // Currently, the UI only works on Windows.  On Linux and Mac we still
 841   // want to show the dangerous file type warning if the file is possibly
 842   // dangerous which means we have to always return false here.
 843 #if defined(OS_WIN)
 844   DownloadCheckResultReason reason = REASON_MAX;
 845   ClientDownloadRequest::DownloadType type =
 846       ClientDownloadRequest::WIN_EXECUTABLE;
 847   return (CheckClientDownloadRequest::IsSupportedDownload(item, target_path,
 848                                                           &reason, &type) &&
 849           (ClientDownloadRequest::ANDROID_APK == type ||
 850            ClientDownloadRequest::WIN_EXECUTABLE == type ||
 851            ClientDownloadRequest::ZIPPED_EXECUTABLE == type));
 852 #else
 853   return false;
 854 #endif
 855 }
 856
 857 void DownloadProtectionService::CancelPendingRequests() {
 858   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 859   for (std::set<scoped_refptr<CheckClientDownloadRequest> >::iterator it =
 860            download_requests_.begin();
 861        it != download_requests_.end();) {
 862     // We need to advance the iterator before we cancel because canceling
 863     // the request will invalidate it when RequestFinished is called below.
 864     scoped_refptr<CheckClientDownloadRequest> tmp = *it++;
 865     tmp->Cancel();
 866   }
 867   DCHECK(download_requests_.empty());
 868 }
 869
 870 void DownloadProtectionService::RequestFinished(
 871     CheckClientDownloadRequest* request) {
 872   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 873   std::set<scoped_refptr<CheckClientDownloadRequest> >::iterator it =
 874       download_requests_.find(request);
 875   DCHECK(it != download_requests_.end());
 876   download_requests_.erase(*it);
 877 }
 878
 879 void DownloadProtectionService::ShowDetailsForDownload(
 880     const content::DownloadItem& item,
 881     content::PageNavigator* navigator) {
 882   GURL learn_more_url(chrome::kDownloadScanningLearnMoreURL);
 883   navigator->OpenURL(
 884       content::OpenURLParams(learn_more_url,
 885                              content::Referrer(),
 886                              NEW_FOREGROUND_TAB,
 887                              content::PAGE_TRANSITION_LINK,
 888                              false));
 889 }
 890
 891 namespace {
 892 // Escapes a certificate attribute so that it can be used in a whitelist
 893 // entry.  Currently, we only escape slashes, since they are used as a
 894 // separator between attributes.
 895 std::string EscapeCertAttribute(const std::string& attribute) {
 896   std::string escaped;
 897   for (size_t i = 0; i < attribute.size(); ++i) {
 898     if (attribute[i] == '%') {
 899       escaped.append("%25");
 900     } else if (attribute[i] == '/') {
 901       escaped.append("%2F");
 902     } else {
 903       escaped.push_back(attribute[i]);
 904     }
 905   }
 906   return escaped;
 907 }
 908 }  // namespace
 909
 910 // static
 911 void DownloadProtectionService::GetCertificateWhitelistStrings(
 912     const net::X509Certificate& certificate,
 913     const net::X509Certificate& issuer,
 914     std::vector<std::string>* whitelist_strings) {
 915   // The whitelist paths are in the format:
 916   // cert/<ascii issuer fingerprint>[/CN=common_name][/O=org][/OU=unit]
 917   //
 918   // Any of CN, O, or OU may be omitted from the whitelist entry, in which
 919   // case they match anything.  However, the attributes that do appear will
 920   // always be in the order shown above.  At least one attribute will always
 921   // be present.
 922
 923   const net::CertPrincipal& subject = certificate.subject();
 924   std::vector<std::string> ou_tokens;
 925   for (size_t i = 0; i < subject.organization_unit_names.size(); ++i) {
 926     ou_tokens.push_back(
 927         "/OU=" + EscapeCertAttribute(subject.organization_unit_names[i]));
 928   }
 929
 930   std::vector<std::string> o_tokens;
 931   for (size_t i = 0; i < subject.organization_names.size(); ++i) {
 932     o_tokens.push_back(
 933         "/O=" + EscapeCertAttribute(subject.organization_names[i]));
 934   }
 935
 936   std::string cn_token;
 937   if (!subject.common_name.empty()) {
 938     cn_token = "/CN=" + EscapeCertAttribute(subject.common_name);
 939   }
 940
 941   std::set<std::string> paths_to_check;
 942   if (!cn_token.empty()) {
 943     paths_to_check.insert(cn_token);
 944   }
 945   for (size_t i = 0; i < o_tokens.size(); ++i) {
 946     paths_to_check.insert(cn_token + o_tokens[i]);
 947     paths_to_check.insert(o_tokens[i]);
 948     for (size_t j = 0; j < ou_tokens.size(); ++j) {
 949       paths_to_check.insert(cn_token + o_tokens[i] + ou_tokens[j]);
 950       paths_to_check.insert(o_tokens[i] + ou_tokens[j]);
 951     }
 952   }
 953   for (size_t i = 0; i < ou_tokens.size(); ++i) {
 954     paths_to_check.insert(cn_token + ou_tokens[i]);
 955     paths_to_check.insert(ou_tokens[i]);
 956   }
 957
 958   std::string issuer_fp = base::HexEncode(issuer.fingerprint().data,
 959                                           sizeof(issuer.fingerprint().data));
 960   for (std::set<std::string>::iterator it = paths_to_check.begin();
 961        it != paths_to_check.end(); ++it) {
 962     whitelist_strings->push_back("cert/" + issuer_fp + *it);
 963   }
 964 }
 965
 966 // static
 967 GURL DownloadProtectionService::GetDownloadRequestUrl() {
 968   GURL url(kDownloadRequestUrl);
 969   std::string api_key = google_apis::GetAPIKey();
 970   if (!api_key.empty())
 971     url = url.Resolve("?key=" + net::EscapeQueryParamValue(api_key, true));
 972
 973   return url;
 974 }
 975
 976 }  // namespace safe_browsing