src/chrome/browser/extensions/install_signer.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 "chrome/browser/extensions/install_signer.h"
   6
   7 #include "base/base64.h"
   8 #include "base/bind.h"
   9 #include "base/command_line.h"
  10 #include "base/json/json_reader.h"
  11 #include "base/json/json_writer.h"
  12 #include "base/lazy_instance.h"
  13 #include "base/message_loop/message_loop.h"
  14 #include "base/metrics/histogram.h"
  15 #include "base/process/process_info.h"
  16 #include "base/stl_util.h"
  17 #include "base/strings/string_number_conversions.h"
  18 #include "base/strings/string_split.h"
  19 #include "base/strings/string_util.h"
  20 #include "base/strings/stringprintf.h"
  21 #include "base/time/time.h"
  22 #include "base/values.h"
  23 #include "chrome/common/chrome_switches.h"
  24 #include "components/crx_file/constants.h"
  25 #include "crypto/random.h"
  26 #include "crypto/secure_hash.h"
  27 #include "crypto/sha2.h"
  28 #include "crypto/signature_verifier.h"
  29 #include "net/url_request/url_fetcher.h"
  30 #include "net/url_request/url_fetcher_delegate.h"
  31 #include "net/url_request/url_request_context_getter.h"
  32 #include "net/url_request/url_request_status.h"
  33 #include "url/gurl.h"
  34
  35 #if defined(ENABLE_RLZ)
  36 #include "rlz/lib/machine_id.h"
  37 #endif
  38
  39 namespace {
  40
  41 using extensions::ExtensionIdSet;
  42
  43 const char kExpireDateKey[] = "expire_date";
  44 const char kExpiryKey[] = "expiry";
  45 const char kHashKey[] = "hash";
  46 const char kIdsKey[] = "ids";
  47 const char kInvalidIdsKey[] = "invalid_ids";
  48 const char kProtocolVersionKey[] = "protocol_version";
  49 const char kSaltKey[] = "salt";
  50 const char kSignatureKey[] = "signature";
  51 const char kSignatureFormatVersionKey[] = "signature_format_version";
  52 const char kTimestampKey[] = "timestamp";
  53
  54 // This allows us to version the format of what we write into the prefs,
  55 // allowing for forward migration, as well as detecting forwards/backwards
  56 // incompatabilities, etc.
  57 const int kSignatureFormatVersion = 2;
  58
  59 const size_t kSaltBytes = 32;
  60
  61 const char kBackendUrl[] =
  62     "https://www.googleapis.com/chromewebstore/v1.1/items/verify";
  63
  64 const char kPublicKeyPEM[] =                                            \
  65     "-----BEGIN PUBLIC KEY-----"                                        \
  66     "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAj/u/XDdjlDyw7gHEtaaa"  \
  67     "sZ9GdG8WOKAyJzXd8HFrDtz2Jcuy7er7MtWvHgNDA0bwpznbI5YdZeV4UfCEsA4S"  \
  68     "rA5b3MnWTHwA1bgbiDM+L9rrqvcadcKuOlTeN48Q0ijmhHlNFbTzvT9W0zw/GKv8"  \
  69     "LgXAHggxtmHQ/Z9PP2QNF5O8rUHHSL4AJ6hNcEKSBVSmbbjeVm4gSXDuED5r0nwx"  \
  70     "vRtupDxGYp8IZpP5KlExqNu1nbkPc+igCTIB6XsqijagzxewUHCdovmkb2JNtskx"  \
  71     "/PMIEv+TvWIx2BzqGp71gSh/dV7SJ3rClvWd2xj8dtxG8FfAWDTIIi0qZXWn2Qhi"  \
  72     "zQIDAQAB"                                                          \
  73     "-----END PUBLIC KEY-----";
  74
  75 GURL GetBackendUrl() {
  76   return GURL(kBackendUrl);
  77 }
  78
  79 // Hashes |salt| with the machine id, base64-encodes it and returns it in
  80 // |result|.
  81 bool HashWithMachineId(const std::string& salt, std::string* result) {
  82   std::string machine_id;
  83 #if defined(ENABLE_RLZ)
  84   if (!rlz_lib::GetMachineId(&machine_id))
  85     return false;
  86 #else
  87   machine_id = "unknown";
  88 #endif
  89
  90   scoped_ptr<crypto::SecureHash> hash(
  91       crypto::SecureHash::Create(crypto::SecureHash::SHA256));
  92
  93   hash->Update(machine_id.data(), machine_id.size());
  94   hash->Update(salt.data(), salt.size());
  95
  96   std::string result_bytes(crypto::kSHA256Length, 0);
  97   hash->Finish(string_as_array(&result_bytes), result_bytes.size());
  98
  99   base::Base64Encode(result_bytes, result);
 100   return true;
 101 }
 102
 103 // Validates that |input| is a string of the form "YYYY-MM-DD".
 104 bool ValidateExpireDateFormat(const std::string& input) {
 105   if (input.length() != 10)
 106     return false;
 107   for (int i = 0; i < 10; i++) {
 108     if (i == 4 ||  i == 7) {
 109       if (input[i] != '-')
 110         return false;
 111     } else if (!IsAsciiDigit(input[i])) {
 112       return false;
 113     }
 114   }
 115   return true;
 116 }
 117
 118 // Sets the value of |key| in |dictionary| to be a list with the contents of
 119 // |ids|.
 120 void SetExtensionIdSet(base::DictionaryValue* dictionary,
 121                        const char* key,
 122                        const ExtensionIdSet& ids) {
 123   base::ListValue* id_list = new base::ListValue();
 124   for (ExtensionIdSet::const_iterator i = ids.begin(); i != ids.end(); ++i)
 125     id_list->AppendString(*i);
 126   dictionary->Set(key, id_list);
 127 }
 128
 129 // Tries to fetch a list of strings from |dictionay| for |key|, and inserts
 130 // them into |ids|. The return value indicates success/failure. Note: on
 131 // failure, |ids| might contain partial results, for instance if some of the
 132 // members of the list were not strings.
 133 bool GetExtensionIdSet(const base::DictionaryValue& dictionary,
 134                        const char* key,
 135                        ExtensionIdSet* ids) {
 136   const base::ListValue* id_list = NULL;
 137   if (!dictionary.GetList(key, &id_list))
 138     return false;
 139   for (base::ListValue::const_iterator i = id_list->begin();
 140        i != id_list->end();
 141        ++i) {
 142     std::string id;
 143     if (!(*i)->GetAsString(&id)) {
 144       return false;
 145     }
 146     ids->insert(id);
 147   }
 148   return true;
 149 }
 150
 151 }  // namespace
 152
 153 namespace extensions {
 154
 155 InstallSignature::InstallSignature() {
 156 }
 157 InstallSignature::~InstallSignature() {
 158 }
 159
 160 void InstallSignature::ToValue(base::DictionaryValue* value) const {
 161   CHECK(value);
 162
 163   value->SetInteger(kSignatureFormatVersionKey, kSignatureFormatVersion);
 164   SetExtensionIdSet(value, kIdsKey, ids);
 165   SetExtensionIdSet(value, kInvalidIdsKey, invalid_ids);
 166   value->SetString(kExpireDateKey, expire_date);
 167   std::string salt_base64;
 168   std::string signature_base64;
 169   base::Base64Encode(salt, &salt_base64);
 170   base::Base64Encode(signature, &signature_base64);
 171   value->SetString(kSaltKey, salt_base64);
 172   value->SetString(kSignatureKey, signature_base64);
 173   value->SetString(kTimestampKey,
 174                    base::Int64ToString(timestamp.ToInternalValue()));
 175 }
 176
 177 // static
 178 scoped_ptr<InstallSignature> InstallSignature::FromValue(
 179     const base::DictionaryValue& value) {
 180
 181   scoped_ptr<InstallSignature> result(new InstallSignature);
 182
 183   // For now we don't want to support any backwards compability, but in the
 184   // future if we do, we would want to put the migration code here.
 185   int format_version = 0;
 186   if (!value.GetInteger(kSignatureFormatVersionKey, &format_version) ||
 187       format_version != kSignatureFormatVersion) {
 188     result.reset();
 189     return result.Pass();
 190   }
 191
 192   std::string salt_base64;
 193   std::string signature_base64;
 194   if (!value.GetString(kExpireDateKey, &result->expire_date) ||
 195       !value.GetString(kSaltKey, &salt_base64) ||
 196       !value.GetString(kSignatureKey, &signature_base64) ||
 197       !base::Base64Decode(salt_base64, &result->salt) ||
 198       !base::Base64Decode(signature_base64, &result->signature)) {
 199     result.reset();
 200     return result.Pass();
 201   }
 202
 203   // Note: earlier versions of the code did not write out a timestamp value
 204   // so older entries will not necessarily have this.
 205   if (value.HasKey(kTimestampKey)) {
 206     std::string timestamp;
 207     int64 timestamp_value = 0;
 208     if (!value.GetString(kTimestampKey, &timestamp) ||
 209         !base::StringToInt64(timestamp, &timestamp_value)) {
 210       result.reset();
 211       return result.Pass();
 212     }
 213     result->timestamp = base::Time::FromInternalValue(timestamp_value);
 214   }
 215
 216   if (!GetExtensionIdSet(value, kIdsKey, &result->ids) ||
 217       !GetExtensionIdSet(value, kInvalidIdsKey, &result->invalid_ids)) {
 218     result.reset();
 219     return result.Pass();
 220   }
 221
 222   return result.Pass();
 223 }
 224
 225
 226 InstallSigner::InstallSigner(net::URLRequestContextGetter* context_getter,
 227                              const ExtensionIdSet& ids)
 228     : ids_(ids), context_getter_(context_getter) {
 229 }
 230
 231 InstallSigner::~InstallSigner() {
 232 }
 233
 234 // static
 235 bool InstallSigner::VerifySignature(const InstallSignature& signature) {
 236   if (signature.ids.empty())
 237     return true;
 238
 239   std::string signed_data;
 240   for (ExtensionIdSet::const_iterator i = signature.ids.begin();
 241        i != signature.ids.end(); ++i)
 242     signed_data.append(*i);
 243
 244   std::string hash_base64;
 245   if (!HashWithMachineId(signature.salt, &hash_base64))
 246     return false;
 247   signed_data.append(hash_base64);
 248
 249   signed_data.append(signature.expire_date);
 250
 251   std::string public_key;
 252   if (!Extension::ParsePEMKeyBytes(kPublicKeyPEM, &public_key))
 253     return false;
 254
 255   crypto::SignatureVerifier verifier;
 256   if (!verifier.VerifyInit(crx_file::kSignatureAlgorithm,
 257                            sizeof(crx_file::kSignatureAlgorithm),
 258                            reinterpret_cast<const uint8*>(
 259                                signature.signature.data()),
 260                            signature.signature.size(),
 261                            reinterpret_cast<const uint8*>(public_key.data()),
 262                            public_key.size()))
 263     return false;
 264
 265   verifier.VerifyUpdate(reinterpret_cast<const uint8*>(signed_data.data()),
 266                         signed_data.size());
 267   return verifier.VerifyFinal();
 268 }
 269
 270
 271 class InstallSigner::FetcherDelegate : public net::URLFetcherDelegate {
 272  public:
 273   explicit FetcherDelegate(const base::Closure& callback)
 274       : callback_(callback) {
 275   }
 276
 277   virtual ~FetcherDelegate() {
 278   }
 279
 280   virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE {
 281     callback_.Run();
 282   }
 283
 284  private:
 285   base::Closure callback_;
 286   DISALLOW_COPY_AND_ASSIGN(FetcherDelegate);
 287 };
 288
 289 // static
 290 ExtensionIdSet InstallSigner::GetForcedNotFromWebstore() {
 291   std::string value = CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
 292       switches::kExtensionsNotWebstore);
 293   if (value.empty())
 294     return ExtensionIdSet();
 295
 296   std::vector<std::string> ids;
 297   base::SplitString(value, ',', &ids);
 298   return ExtensionIdSet(ids.begin(), ids.end());
 299 }
 300
 301 namespace {
 302
 303 static int g_request_count = 0;
 304
 305 base::LazyInstance<base::TimeTicks> g_last_request_time =
 306     LAZY_INSTANCE_INITIALIZER;
 307
 308 base::LazyInstance<base::ThreadChecker> g_single_thread_checker =
 309     LAZY_INSTANCE_INITIALIZER;
 310
 311 void LogRequestStartHistograms() {
 312   // Make sure we only ever call this from one thread, so that we don't have to
 313   // worry about race conditions setting g_last_request_time.
 314   DCHECK(g_single_thread_checker.Get().CalledOnValidThread());
 315
 316   // CurrentProcessInfo::CreationTime is only defined on some platforms.
 317 #if defined(OS_MACOSX) || defined(OS_WIN) || defined(OS_LINUX)
 318   const base::Time process_creation_time =
 319       base::CurrentProcessInfo::CreationTime();
 320   UMA_HISTOGRAM_COUNTS("ExtensionInstallSigner.UptimeAtTimeOfRequest",
 321                        (base::Time::Now() - process_creation_time).InSeconds());
 322 #endif  // defined(OS_MACOSX) || defined(OS_WIN) || defined(OS_LINUX)
 323
 324   base::TimeDelta delta;
 325   base::TimeTicks now = base::TimeTicks::Now();
 326   if (!g_last_request_time.Get().is_null())
 327     delta = now - g_last_request_time.Get();
 328   g_last_request_time.Get() = now;
 329   UMA_HISTOGRAM_COUNTS("ExtensionInstallSigner.SecondsSinceLastRequest",
 330                        delta.InSeconds());
 331
 332   g_request_count += 1;
 333   UMA_HISTOGRAM_COUNTS_100("ExtensionInstallSigner.RequestCount",
 334                            g_request_count);
 335 }
 336
 337 }  // namespace
 338
 339 void InstallSigner::GetSignature(const SignatureCallback& callback) {
 340   CHECK(!url_fetcher_.get());
 341   CHECK(callback_.is_null());
 342   CHECK(salt_.empty());
 343   callback_ = callback;
 344
 345   // If the set of ids is empty, just return an empty signature and skip the
 346   // call to the server.
 347   if (ids_.empty()) {
 348     if (!callback_.is_null())
 349       callback_.Run(scoped_ptr<InstallSignature>(new InstallSignature()));
 350     return;
 351   }
 352
 353   salt_ = std::string(kSaltBytes, 0);
 354   DCHECK_EQ(kSaltBytes, salt_.size());
 355   crypto::RandBytes(string_as_array(&salt_), salt_.size());
 356
 357   std::string hash_base64;
 358   if (!HashWithMachineId(salt_, &hash_base64)) {
 359     ReportErrorViaCallback();
 360     return;
 361   }
 362
 363   if (!context_getter_) {
 364     ReportErrorViaCallback();
 365     return;
 366   }
 367
 368   base::Closure closure = base::Bind(&InstallSigner::ParseFetchResponse,
 369                                      base::Unretained(this));
 370
 371   delegate_.reset(new FetcherDelegate(closure));
 372   url_fetcher_.reset(net::URLFetcher::Create(
 373       GetBackendUrl(), net::URLFetcher::POST, delegate_.get()));
 374   url_fetcher_->SetRequestContext(context_getter_);
 375
 376   // The request protocol is JSON of the form:
 377   // {
 378   //   "protocol_version": "1",
 379   //   "hash": "<base64-encoded hash value here>",
 380   //   "ids": [ "<id1>", "id2" ]
 381   // }
 382   base::DictionaryValue dictionary;
 383   dictionary.SetInteger(kProtocolVersionKey, 1);
 384   dictionary.SetString(kHashKey, hash_base64);
 385   scoped_ptr<base::ListValue> id_list(new base::ListValue);
 386   for (ExtensionIdSet::const_iterator i = ids_.begin(); i != ids_.end(); ++i) {
 387     id_list->AppendString(*i);
 388   }
 389   dictionary.Set(kIdsKey, id_list.release());
 390   std::string json;
 391   base::JSONWriter::Write(&dictionary, &json);
 392   if (json.empty()) {
 393     ReportErrorViaCallback();
 394     return;
 395   }
 396   url_fetcher_->SetUploadData("application/json", json);
 397   LogRequestStartHistograms();
 398   request_start_time_ = base::Time::Now();
 399   VLOG(1) << "Sending request: " << json;
 400   url_fetcher_->Start();
 401 }
 402
 403 void InstallSigner::ReportErrorViaCallback() {
 404   InstallSignature* null_signature = NULL;
 405   if (!callback_.is_null())
 406     callback_.Run(scoped_ptr<InstallSignature>(null_signature));
 407 }
 408
 409 void InstallSigner::ParseFetchResponse() {
 410   bool fetch_success = url_fetcher_->GetStatus().is_success();
 411   UMA_HISTOGRAM_BOOLEAN("ExtensionInstallSigner.FetchSuccess", fetch_success);
 412
 413   std::string response;
 414   if (fetch_success) {
 415     if (!url_fetcher_->GetResponseAsString(&response))
 416       response.clear();
 417   }
 418   UMA_HISTOGRAM_BOOLEAN("ExtensionInstallSigner.GetResponseSuccess",
 419                         !response.empty());
 420   if (!fetch_success || response.empty()) {
 421     ReportErrorViaCallback();
 422     return;
 423   }
 424   VLOG(1) << "Got response: " << response;
 425
 426   // The response is JSON of the form:
 427   // {
 428   //   "protocol_version": "1",
 429   //   "signature": "<base64-encoded signature>",
 430   //   "expiry": "<date in YYYY-MM-DD form>",
 431   //   "invalid_ids": [ "<id3>", "<id4>" ]
 432   // }
 433   // where |invalid_ids| is a list of ids from the original request that
 434   // could not be verified to be in the webstore.
 435
 436   base::DictionaryValue* dictionary = NULL;
 437   scoped_ptr<base::Value> parsed(base::JSONReader::Read(response));
 438   bool json_success = parsed.get() && parsed->GetAsDictionary(&dictionary);
 439   UMA_HISTOGRAM_BOOLEAN("ExtensionInstallSigner.ParseJsonSuccess",
 440                         json_success);
 441   if (!json_success) {
 442     ReportErrorViaCallback();
 443     return;
 444   }
 445
 446   int protocol_version = 0;
 447   std::string signature_base64;
 448   std::string signature;
 449   std::string expire_date;
 450
 451   dictionary->GetInteger(kProtocolVersionKey, &protocol_version);
 452   dictionary->GetString(kSignatureKey, &signature_base64);
 453   dictionary->GetString(kExpiryKey, &expire_date);
 454
 455   bool fields_success =
 456       protocol_version == 1 && !signature_base64.empty() &&
 457       ValidateExpireDateFormat(expire_date) &&
 458       base::Base64Decode(signature_base64, &signature);
 459   UMA_HISTOGRAM_BOOLEAN("ExtensionInstallSigner.ParseFieldsSuccess",
 460                         fields_success);
 461   if (!fields_success) {
 462     ReportErrorViaCallback();
 463     return;
 464   }
 465
 466   ExtensionIdSet invalid_ids;
 467   const base::ListValue* invalid_ids_list = NULL;
 468   if (dictionary->GetList(kInvalidIdsKey, &invalid_ids_list)) {
 469     for (size_t i = 0; i < invalid_ids_list->GetSize(); i++) {
 470       std::string id;
 471       if (!invalid_ids_list->GetString(i, &id)) {
 472         ReportErrorViaCallback();
 473         return;
 474       }
 475       invalid_ids.insert(id);
 476     }
 477   }
 478
 479   HandleSignatureResult(signature, expire_date, invalid_ids);
 480 }
 481
 482 void InstallSigner::HandleSignatureResult(const std::string& signature,
 483                                           const std::string& expire_date,
 484                                           const ExtensionIdSet& invalid_ids) {
 485   ExtensionIdSet valid_ids =
 486       base::STLSetDifference<ExtensionIdSet>(ids_, invalid_ids);
 487
 488   scoped_ptr<InstallSignature> result;
 489   if (!signature.empty()) {
 490     result.reset(new InstallSignature);
 491     result->ids = valid_ids;
 492     result->invalid_ids = invalid_ids;
 493     result->salt = salt_;
 494     result->signature = signature;
 495     result->expire_date = expire_date;
 496     result->timestamp = request_start_time_;
 497     bool verified = VerifySignature(*result);
 498     UMA_HISTOGRAM_BOOLEAN("ExtensionInstallSigner.ResultWasValid", verified);
 499     UMA_HISTOGRAM_COUNTS_100("ExtensionInstallSigner.InvalidCount",
 500                              invalid_ids.size());
 501     if (!verified)
 502       result.reset();
 503   }
 504
 505   if (!callback_.is_null())
 506     callback_.Run(result.Pass());
 507 }
 508
 509
 510 }  // namespace extensions