src/chrome/browser/ssl/chrome_ssl_host_state_delegate.cc

   1 // Copyright 2014 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/ssl/chrome_ssl_host_state_delegate.h"
   6
   7 #include "base/base64.h"
   8 #include "base/bind.h"
   9 #include "base/command_line.h"
  10 #include "base/logging.h"
  11 #include "base/metrics/field_trial.h"
  12 #include "base/strings/string_number_conversions.h"
  13 #include "base/time/clock.h"
  14 #include "base/time/default_clock.h"
  15 #include "base/time/time.h"
  16 #include "chrome/browser/content_settings/host_content_settings_map.h"
  17 #include "chrome/browser/profiles/profile.h"
  18 #include "chrome/common/chrome_switches.h"
  19 #include "components/content_settings/core/common/content_settings_types.h"
  20 #include "components/variations/variations_associated_data.h"
  21 #include "net/base/hash_value.h"
  22 #include "net/cert/x509_certificate.h"
  23 #include "net/http/http_transaction_factory.h"
  24 #include "net/url_request/url_request_context.h"
  25 #include "net/url_request/url_request_context_getter.h"
  26 #include "url/gurl.h"
  27
  28 namespace {
  29
  30 // Switch value that specifies that certificate decisions should be forgotten at
  31 // the end of the current session.
  32 const int64 kForgetAtSessionEndSwitchValue = -1;
  33
  34 // Experiment information
  35 const char kRememberCertificateErrorDecisionsFieldTrialName[] =
  36     "RememberCertificateErrorDecisions";
  37 const char kRememberCertificateErrorDecisionsFieldTrialDefaultGroup[] =
  38     "Default";
  39 const char kRememberCertificateErrorDecisionsFieldTrialLengthParam[] = "length";
  40
  41 // Keys for the per-site error + certificate finger to judgement content
  42 // settings map.
  43 const char kSSLCertDecisionCertErrorMapKey[] = "cert_exceptions_map";
  44 const char kSSLCertDecisionExpirationTimeKey[] = "decision_expiration_time";
  45 const char kSSLCertDecisionVersionKey[] = "version";
  46
  47 const int kDefaultSSLCertDecisionVersion = 1;
  48
  49 // Closes all idle network connections for the given URLRequestContext. This is
  50 // a big hammer and should be wielded with extreme caution as it can have a big,
  51 // negative impact on network performance. In this case, it is used by
  52 // RevokeUserDecisionsHard, which should only be called by rare, user initiated
  53 // events. See the comment before RevokeUserDecisionsHard implementation for
  54 // more information.
  55 void CloseIdleConnections(
  56     scoped_refptr<net::URLRequestContextGetter> url_request_context_getter) {
  57   url_request_context_getter->
  58       GetURLRequestContext()->
  59       http_transaction_factory()->
  60       GetSession()->
  61       CloseIdleConnections();
  62 }
  63
  64 // All SSL decisions are per host (and are shared arcoss schemes), so this
  65 // canonicalizes all hosts into a secure scheme GURL to use with content
  66 // settings. The returned GURL will be the passed in host with an empty path and
  67 // https:// as the scheme.
  68 GURL GetSecureGURLForHost(const std::string& host) {
  69   std::string url = "https://" + host;
  70   return GURL(url);
  71 }
  72
  73 // This is a helper function that returns the length of time before a
  74 // certificate decision expires based on the command line flags. Returns a
  75 // non-negative value in seconds or a value of -1  indicating that decisions
  76 // should not be remembered after the current session has ended (but should be
  77 // remembered indefinitely as long as the session does not end), which is the
  78 // "old" style of certificate decision memory. Uses the experimental group
  79 // unless overridden by a command line flag.
  80 int64 GetExpirationDelta() {
  81   // Check command line flags first to give them priority, then check
  82   // experimental groups.
  83   if (CommandLine::ForCurrentProcess()->HasSwitch(
  84           switches::kRememberCertErrorDecisions)) {
  85     std::string switch_value =
  86         CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
  87             switches::kRememberCertErrorDecisions);
  88     int64 expiration_delta;
  89     if (!base::StringToInt64(base::StringPiece(switch_value),
  90                              &expiration_delta) ||
  91         expiration_delta < kForgetAtSessionEndSwitchValue) {
  92       LOG(ERROR) << "Failed to parse the certificate error decision "
  93                  << "memory length: " << switch_value;
  94       return kForgetAtSessionEndSwitchValue;
  95     }
  96
  97     return expiration_delta;
  98   }
  99
 100   // If the user is in the field trial, set the expiration to the length
 101   // associated with that experimental group.  The default group cannot have
 102   // parameters associated with it, so it needs to be handled explictly.
 103   std::string group_name = base::FieldTrialList::FindFullName(
 104       kRememberCertificateErrorDecisionsFieldTrialName);
 105   if (!group_name.empty() &&
 106       group_name.compare(
 107           kRememberCertificateErrorDecisionsFieldTrialDefaultGroup) != 0) {
 108     int64 field_trial_param_length;
 109     std::string param = variations::GetVariationParamValue(
 110         kRememberCertificateErrorDecisionsFieldTrialName,
 111         kRememberCertificateErrorDecisionsFieldTrialLengthParam);
 112     if (!param.empty() && base::StringToInt64(base::StringPiece(param),
 113                                               &field_trial_param_length)) {
 114       return field_trial_param_length;
 115     }
 116   }
 117
 118   return kForgetAtSessionEndSwitchValue;
 119 }
 120
 121 std::string GetKey(net::X509Certificate* cert, net::CertStatus error) {
 122   // Since a security decision will be made based on the fingerprint, Chrome
 123   // should use the SHA-256 fingerprint for the certificate.
 124   net::SHA256HashValue fingerprint =
 125       net::X509Certificate::CalculateChainFingerprint256(
 126           cert->os_cert_handle(), cert->GetIntermediateCertificates());
 127   std::string base64_fingerprint;
 128   base::Base64Encode(
 129       base::StringPiece(reinterpret_cast<const char*>(fingerprint.data),
 130                         sizeof(fingerprint.data)),
 131       &base64_fingerprint);
 132   return base::UintToString(error) + base64_fingerprint;
 133 }
 134
 135 }  // namespace
 136
 137 // This helper function gets the dictionary of certificate fingerprints to
 138 // errors of certificates that have been accepted by the user from the content
 139 // dictionary that has been passed in. The returned pointer is owned by the the
 140 // argument dict that is passed in.
 141 //
 142 // If create_entries is set to |DoNotCreateDictionaryEntries|,
 143 // GetValidCertDecisionsDict will return NULL if there is anything invalid about
 144 // the setting, such as an invalid version or invalid value types (in addition
 145 // to there not be any values in the dictionary). If create_entries is set to
 146 // |CreateDictionaryEntries|, if no dictionary is found or the decisions are
 147 // expired, a new dictionary will be created
 148 base::DictionaryValue* ChromeSSLHostStateDelegate::GetValidCertDecisionsDict(
 149     base::DictionaryValue* dict,
 150     CreateDictionaryEntriesDisposition create_entries,
 151     bool* expired_previous_decision) {
 152   // This needs to be done first in case the method is short circuited by an
 153   // early failure.
 154   *expired_previous_decision = false;
 155
 156   // Extract the version of the certificate decision structure from the content
 157   // setting.
 158   int version;
 159   bool success = dict->GetInteger(kSSLCertDecisionVersionKey, &version);
 160   if (!success) {
 161     if (create_entries == DoNotCreateDictionaryEntries)
 162       return NULL;
 163
 164     dict->SetInteger(kSSLCertDecisionVersionKey,
 165                      kDefaultSSLCertDecisionVersion);
 166     version = kDefaultSSLCertDecisionVersion;
 167   }
 168
 169   // If the version is somehow a newer version than Chrome can handle, there's
 170   // really nothing to do other than fail silently and pretend it doesn't exist
 171   // (or is malformed).
 172   if (version > kDefaultSSLCertDecisionVersion) {
 173     LOG(ERROR) << "Failed to parse a certificate error exception that is in a "
 174                << "newer version format (" << version << ") than is supported ("
 175                << kDefaultSSLCertDecisionVersion << ")";
 176     return NULL;
 177   }
 178
 179   // Extract the certificate decision's expiration time from the content
 180   // setting. If there is no expiration time, that means it should never expire
 181   // and it should reset only at session restart, so skip all of the expiration
 182   // checks.
 183   bool expired = false;
 184   base::Time now = clock_->Now();
 185   base::Time decision_expiration;
 186   if (dict->HasKey(kSSLCertDecisionExpirationTimeKey)) {
 187     std::string decision_expiration_string;
 188     int64 decision_expiration_int64;
 189     success = dict->GetString(kSSLCertDecisionExpirationTimeKey,
 190                               &decision_expiration_string);
 191     if (!base::StringToInt64(base::StringPiece(decision_expiration_string),
 192                              &decision_expiration_int64)) {
 193       LOG(ERROR) << "Failed to parse a certificate error exception that has a "
 194                  << "bad value for an expiration time: "
 195                  << decision_expiration_string;
 196       return NULL;
 197     }
 198     decision_expiration =
 199         base::Time::FromInternalValue(decision_expiration_int64);
 200   }
 201
 202   // Check to see if the user's certificate decision has expired.
 203   // - Expired and |create_entries| is DoNotCreateDictionaryEntries, return
 204   // NULL.
 205   // - Expired and |create_entries| is CreateDictionaryEntries, update the
 206   // expiration time.
 207   if (should_remember_ssl_decisions_ !=
 208           ForgetSSLExceptionDecisionsAtSessionEnd &&
 209       decision_expiration.ToInternalValue() <= now.ToInternalValue()) {
 210     *expired_previous_decision = true;
 211
 212     if (create_entries == DoNotCreateDictionaryEntries)
 213       return NULL;
 214
 215     expired = true;
 216     base::Time expiration_time =
 217         now + default_ssl_cert_decision_expiration_delta_;
 218     // Unfortunately, JSON (and thus content settings) doesn't support int64
 219     // values, only doubles. Since this mildly depends on precision, it is
 220     // better to store the value as a string.
 221     dict->SetString(kSSLCertDecisionExpirationTimeKey,
 222                     base::Int64ToString(expiration_time.ToInternalValue()));
 223   }
 224
 225   // Extract the map of certificate fingerprints to errors from the setting.
 226   base::DictionaryValue* cert_error_dict = NULL;  // Will be owned by dict
 227   if (expired ||
 228       !dict->GetDictionary(kSSLCertDecisionCertErrorMapKey, &cert_error_dict)) {
 229     if (create_entries == DoNotCreateDictionaryEntries)
 230       return NULL;
 231
 232     cert_error_dict = new base::DictionaryValue();
 233     // dict takes ownership of cert_error_dict
 234     dict->Set(kSSLCertDecisionCertErrorMapKey, cert_error_dict);
 235   }
 236
 237   return cert_error_dict;
 238 }
 239
 240 // If |should_remember_ssl_decisions_| is
 241 // ForgetSSLExceptionDecisionsAtSessionEnd, that means that all invalid
 242 // certificate proceed decisions should be forgotten when the session ends. At
 243 // attempt is made in the destructor to remove the entries, but in the case that
 244 // things didn't shut down cleanly, on start, Clear is called to guarantee a
 245 // clean state.
 246 ChromeSSLHostStateDelegate::ChromeSSLHostStateDelegate(Profile* profile)
 247     : clock_(new base::DefaultClock()), profile_(profile) {
 248   int64 expiration_delta = GetExpirationDelta();
 249   if (expiration_delta == kForgetAtSessionEndSwitchValue) {
 250     should_remember_ssl_decisions_ = ForgetSSLExceptionDecisionsAtSessionEnd;
 251     expiration_delta = 0;
 252     Clear();
 253   } else {
 254     should_remember_ssl_decisions_ = RememberSSLExceptionDecisionsForDelta;
 255   }
 256   default_ssl_cert_decision_expiration_delta_ =
 257       base::TimeDelta::FromSeconds(expiration_delta);
 258 }
 259
 260 ChromeSSLHostStateDelegate::~ChromeSSLHostStateDelegate() {
 261   if (should_remember_ssl_decisions_ == ForgetSSLExceptionDecisionsAtSessionEnd)
 262     Clear();
 263 }
 264
 265 void ChromeSSLHostStateDelegate::DenyCert(const std::string& host,
 266                                           net::X509Certificate* cert,
 267                                           net::CertStatus error) {
 268   ChangeCertPolicy(host, cert, error, net::CertPolicy::DENIED);
 269 }
 270
 271 void ChromeSSLHostStateDelegate::AllowCert(const std::string& host,
 272                                            net::X509Certificate* cert,
 273                                            net::CertStatus error) {
 274   ChangeCertPolicy(host, cert, error, net::CertPolicy::ALLOWED);
 275 }
 276
 277 void ChromeSSLHostStateDelegate::Clear() {
 278   profile_->GetHostContentSettingsMap()->ClearSettingsForOneType(
 279       CONTENT_SETTINGS_TYPE_SSL_CERT_DECISIONS);
 280 }
 281
 282 net::CertPolicy::Judgment ChromeSSLHostStateDelegate::QueryPolicy(
 283     const std::string& host,
 284     net::X509Certificate* cert,
 285     net::CertStatus error,
 286     bool* expired_previous_decision) {
 287   HostContentSettingsMap* map = profile_->GetHostContentSettingsMap();
 288   GURL url = GetSecureGURLForHost(host);
 289   scoped_ptr<base::Value> value(map->GetWebsiteSetting(
 290       url, url, CONTENT_SETTINGS_TYPE_SSL_CERT_DECISIONS, std::string(), NULL));
 291
 292   // Set a default value in case this method is short circuited and doesn't do a
 293   // full query.
 294   *expired_previous_decision = false;
 295   if (!value.get() || !value->IsType(base::Value::TYPE_DICTIONARY))
 296     return net::CertPolicy::UNKNOWN;
 297
 298   base::DictionaryValue* dict;  // Owned by value
 299   int policy_decision;
 300   bool success = value->GetAsDictionary(&dict);
 301   DCHECK(success);
 302
 303   base::DictionaryValue* cert_error_dict;  // Owned by value
 304   cert_error_dict = GetValidCertDecisionsDict(
 305       dict, DoNotCreateDictionaryEntries, expired_previous_decision);
 306   if (!cert_error_dict) {
 307     // This revoke is necessary to clear any old expired setting that may
 308     // lingering in the case that an old decision expried.
 309     RevokeUserDecisions(host);
 310     return net::CertPolicy::UNKNOWN;
 311   }
 312
 313   success = cert_error_dict->GetIntegerWithoutPathExpansion(GetKey(cert, error),
 314                                                             &policy_decision);
 315
 316   // If a policy decision was successfully retrieved and it's a valid value of
 317   // ALLOWED or DENIED, return the valid value. Otherwise, return UNKNOWN.
 318   if (success && policy_decision == net::CertPolicy::Judgment::ALLOWED)
 319     return net::CertPolicy::Judgment::ALLOWED;
 320   else if (success && policy_decision == net::CertPolicy::Judgment::DENIED)
 321     return net::CertPolicy::Judgment::DENIED;
 322
 323   return net::CertPolicy::Judgment::UNKNOWN;
 324 }
 325
 326 void ChromeSSLHostStateDelegate::RevokeUserDecisions(const std::string& host) {
 327   GURL url = GetSecureGURLForHost(host);
 328   const ContentSettingsPattern pattern =
 329       ContentSettingsPattern::FromURLNoWildcard(url);
 330   HostContentSettingsMap* map = profile_->GetHostContentSettingsMap();
 331
 332   map->SetWebsiteSetting(pattern,
 333                          pattern,
 334                          CONTENT_SETTINGS_TYPE_SSL_CERT_DECISIONS,
 335                          std::string(),
 336                          NULL);
 337 }
 338
 339 // TODO(jww): This will revoke all of the decisions in the browser context.
 340 // However, the networking stack actually keeps track of its own list of
 341 // exceptions per-HttpNetworkTransaction in the SSLConfig structure (see the
 342 // allowed_bad_certs Vector in net/ssl/ssl_config.h). This dual-tracking of
 343 // exceptions introduces a problem where the browser context can revoke a
 344 // certificate, but if a transaction reuses a cached version of the SSLConfig
 345 // (probably from a pooled socket), it may bypass the intestitial layer.
 346 //
 347 // Over time, the cached versions should expire and it should converge on
 348 // showing the interstitial. We probably need to introduce into the networking
 349 // stack a way revoke SSLConfig's allowed_bad_certs lists per socket.
 350 //
 351 // For now, RevokeUserDecisionsHard is our solution for the rare case where it
 352 // is necessary to revoke the preferences immediately. It does so by flushing
 353 // idle sockets.
 354 void ChromeSSLHostStateDelegate::RevokeUserDecisionsHard(
 355     const std::string& host) {
 356   RevokeUserDecisions(host);
 357   scoped_refptr<net::URLRequestContextGetter> getter(
 358       profile_->GetRequestContext());
 359   profile_->GetRequestContext()->GetNetworkTaskRunner()->PostTask(
 360       FROM_HERE, base::Bind(&CloseIdleConnections, getter));
 361 }
 362
 363 bool ChromeSSLHostStateDelegate::HasUserDecision(const std::string& host) {
 364   GURL url = GetSecureGURLForHost(host);
 365   const ContentSettingsPattern pattern =
 366       ContentSettingsPattern::FromURLNoWildcard(url);
 367   HostContentSettingsMap* map = profile_->GetHostContentSettingsMap();
 368
 369   scoped_ptr<base::Value> value(map->GetWebsiteSetting(
 370       url, url, CONTENT_SETTINGS_TYPE_SSL_CERT_DECISIONS, std::string(), NULL));
 371
 372   if (!value.get() || !value->IsType(base::Value::TYPE_DICTIONARY))
 373     return false;
 374
 375   base::DictionaryValue* dict;  // Owned by value
 376   bool success = value->GetAsDictionary(&dict);
 377   DCHECK(success);
 378
 379   for (base::DictionaryValue::Iterator it(*dict); !it.IsAtEnd(); it.Advance()) {
 380     int policy_decision;  // Owned by dict
 381     success = it.value().GetAsInteger(&policy_decision);
 382     if (success && (static_cast<net::CertPolicy::Judgment>(policy_decision) !=
 383                     net::CertPolicy::UNKNOWN))
 384       return true;
 385   }
 386
 387   return false;
 388 }
 389
 390 void ChromeSSLHostStateDelegate::HostRanInsecureContent(const std::string& host,
 391                                                         int pid) {
 392   ran_insecure_content_hosts_.insert(BrokenHostEntry(host, pid));
 393 }
 394
 395 bool ChromeSSLHostStateDelegate::DidHostRunInsecureContent(
 396     const std::string& host,
 397     int pid) const {
 398   return !!ran_insecure_content_hosts_.count(BrokenHostEntry(host, pid));
 399 }
 400 void ChromeSSLHostStateDelegate::SetClock(scoped_ptr<base::Clock> clock) {
 401   clock_.reset(clock.release());
 402 }
 403
 404 void ChromeSSLHostStateDelegate::ChangeCertPolicy(
 405     const std::string& host,
 406     net::X509Certificate* cert,
 407     net::CertStatus error,
 408     net::CertPolicy::Judgment judgment) {
 409   GURL url = GetSecureGURLForHost(host);
 410   const ContentSettingsPattern pattern =
 411       ContentSettingsPattern::FromURLNoWildcard(url);
 412   HostContentSettingsMap* map = profile_->GetHostContentSettingsMap();
 413   scoped_ptr<base::Value> value(map->GetWebsiteSetting(
 414       url, url, CONTENT_SETTINGS_TYPE_SSL_CERT_DECISIONS, std::string(), NULL));
 415
 416   if (!value.get() || !value->IsType(base::Value::TYPE_DICTIONARY))
 417     value.reset(new base::DictionaryValue());
 418
 419   base::DictionaryValue* dict;
 420   bool success = value->GetAsDictionary(&dict);
 421   DCHECK(success);
 422
 423   bool expired_previous_decision;  // unused value in this function
 424   base::DictionaryValue* cert_dict = GetValidCertDecisionsDict(
 425       dict, CreateDictionaryEntries, &expired_previous_decision);
 426   // If a a valid certificate dictionary cannot be extracted from the content
 427   // setting, that means it's in an unknown format. Unfortunately, there's
 428   // nothing to be done in that case, so a silent fail is the only option.
 429   if (!cert_dict)
 430     return;
 431
 432   dict->SetIntegerWithoutPathExpansion(kSSLCertDecisionVersionKey,
 433                                        kDefaultSSLCertDecisionVersion);
 434   cert_dict->SetIntegerWithoutPathExpansion(GetKey(cert, error), judgment);
 435
 436   // The map takes ownership of the value, so it is released in the call to
 437   // SetWebsiteSetting.
 438   map->SetWebsiteSetting(pattern,
 439                          pattern,
 440                          CONTENT_SETTINGS_TYPE_SSL_CERT_DECISIONS,
 441                          std::string(),
 442                          value.release());
 443 }