chrome/browser/extensions/chrome_content_verifier_delegate.cc

   1 // Copyright 2015 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/chrome_content_verifier_delegate.h"
   6
   7 #include "base/base_switches.h"
   8 #include "base/command_line.h"
   9 #include "base/metrics/field_trial.h"
  10 #include "base/metrics/histogram.h"
  11 #include "base/strings/string_util.h"
  12 #include "base/version.h"
  13 #include "chrome/browser/extensions/extension_service.h"
  14 #include "chrome/common/chrome_switches.h"
  15 #include "chrome/common/extensions/extension_constants.h"
  16 #include "extensions/browser/extension_prefs.h"
  17 #include "extensions/browser/extension_registry.h"
  18 #include "extensions/browser/extension_system.h"
  19 #include "extensions/browser/management_policy.h"
  20 #include "extensions/common/extension.h"
  21 #include "extensions/common/extension_urls.h"
  22 #include "extensions/common/extensions_client.h"
  23 #include "extensions/common/manifest.h"
  24 #include "extensions/common/manifest_url_handlers.h"
  25 #include "net/base/escape.h"
  26
  27 #if defined(OS_CHROMEOS)
  28 #include "chrome/browser/extensions/extension_assets_manager_chromeos.h"
  29 #endif
  30
  31 namespace {
  32
  33 const char kContentVerificationExperimentName[] =
  34     "ExtensionContentVerification";
  35
  36 }  // namespace
  37
  38 namespace extensions {
  39
  40 // static
  41 ContentVerifierDelegate::Mode ChromeContentVerifierDelegate::GetDefaultMode() {
  42   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
  43
  44   Mode experiment_value = NONE;
  45   const std::string group =
  46       base::FieldTrialList::FindFullName(kContentVerificationExperimentName);
  47   if (group == "EnforceStrict")
  48     experiment_value = ContentVerifierDelegate::ENFORCE_STRICT;
  49   else if (group == "Enforce")
  50     experiment_value = ContentVerifierDelegate::ENFORCE;
  51   else if (group == "Bootstrap")
  52     experiment_value = ContentVerifierDelegate::BOOTSTRAP;
  53
  54   // The field trial value that normally comes from the server can be
  55   // overridden on the command line, which we don't want to allow since
  56   // malware can set chrome command line flags. There isn't currently a way
  57   // to find out what the server-provided value is in this case, so we
  58   // conservatively default to the strictest mode if we detect our experiment
  59   // name being overridden.
  60   if (command_line->HasSwitch(switches::kForceFieldTrials)) {
  61     std::string forced_trials =
  62         command_line->GetSwitchValueASCII(switches::kForceFieldTrials);
  63     if (forced_trials.find(kContentVerificationExperimentName) !=
  64         std::string::npos)
  65       experiment_value = ContentVerifierDelegate::ENFORCE_STRICT;
  66   }
  67
  68   Mode cmdline_value = NONE;
  69   if (command_line->HasSwitch(switches::kExtensionContentVerification)) {
  70     std::string switch_value = command_line->GetSwitchValueASCII(
  71         switches::kExtensionContentVerification);
  72     if (switch_value == switches::kExtensionContentVerificationBootstrap)
  73       cmdline_value = ContentVerifierDelegate::BOOTSTRAP;
  74     else if (switch_value == switches::kExtensionContentVerificationEnforce)
  75       cmdline_value = ContentVerifierDelegate::ENFORCE;
  76     else if (switch_value ==
  77              switches::kExtensionContentVerificationEnforceStrict)
  78       cmdline_value = ContentVerifierDelegate::ENFORCE_STRICT;
  79     else
  80       // If no value was provided (or the wrong one), just default to enforce.
  81       cmdline_value = ContentVerifierDelegate::ENFORCE;
  82   }
  83
  84   // We don't want to allow the command-line flags to eg disable enforcement
  85   // if the experiment group says it should be on, or malware may just modify
  86   // the command line flags. So return the more restrictive of the 2 values.
  87   return std::max(experiment_value, cmdline_value);
  88 }
  89
  90 ChromeContentVerifierDelegate::ChromeContentVerifierDelegate(
  91     content::BrowserContext* context)
  92     : context_(context), default_mode_(GetDefaultMode()) {
  93 }
  94
  95 ChromeContentVerifierDelegate::~ChromeContentVerifierDelegate() {
  96 }
  97
  98 ContentVerifierDelegate::Mode ChromeContentVerifierDelegate::ShouldBeVerified(
  99     const Extension& extension) {
 100 #if defined(OS_CHROMEOS)
 101   if (ExtensionAssetsManagerChromeOS::IsSharedInstall(&extension))
 102     return ContentVerifierDelegate::ENFORCE_STRICT;
 103 #endif
 104
 105   if (!extension.is_extension() && !extension.is_legacy_packaged_app())
 106     return ContentVerifierDelegate::NONE;
 107   if (!Manifest::IsAutoUpdateableLocation(extension.location()))
 108     return ContentVerifierDelegate::NONE;
 109
 110   if (!ManifestURL::UpdatesFromGallery(&extension)) {
 111     // It's possible that the webstore update url was overridden for testing
 112     // so also consider extensions with the default (production) update url
 113     // to be from the store as well.
 114     GURL default_webstore_url = extension_urls::GetDefaultWebstoreUpdateUrl();
 115     if (ManifestURL::GetUpdateURL(&extension) != default_webstore_url)
 116       return ContentVerifierDelegate::NONE;
 117   }
 118
 119   return default_mode_;
 120 }
 121
 122 ContentVerifierKey ChromeContentVerifierDelegate::GetPublicKey() {
 123   return ContentVerifierKey(extension_misc::kWebstoreSignaturesPublicKey,
 124                             extension_misc::kWebstoreSignaturesPublicKeySize);
 125 }
 126
 127 GURL ChromeContentVerifierDelegate::GetSignatureFetchUrl(
 128     const std::string& extension_id,
 129     const base::Version& version) {
 130   // TODO(asargent) Factor out common code from the extension updater's
 131   // ManifestFetchData class that can be shared for use here.
 132   std::vector<std::string> parts;
 133   parts.push_back("uc");
 134   parts.push_back("installsource=signature");
 135   parts.push_back("id=" + extension_id);
 136   parts.push_back("v=" + version.GetString());
 137   std::string x_value =
 138       net::EscapeQueryParamValue(base::JoinString(parts, "&"), true);
 139   std::string query = "response=redirect&x=" + x_value;
 140
 141   GURL base_url = extension_urls::GetWebstoreUpdateUrl();
 142   GURL::Replacements replacements;
 143   replacements.SetQuery(query.c_str(), url::Component(0, query.length()));
 144   return base_url.ReplaceComponents(replacements);
 145 }
 146
 147 std::set<base::FilePath> ChromeContentVerifierDelegate::GetBrowserImagePaths(
 148     const extensions::Extension* extension) {
 149   return ExtensionsClient::Get()->GetBrowserImagePaths(extension);
 150 }
 151
 152 void ChromeContentVerifierDelegate::VerifyFailed(
 153     const std::string& extension_id,
 154     ContentVerifyJob::FailureReason reason) {
 155   ExtensionRegistry* registry = ExtensionRegistry::Get(context_);
 156   const Extension* extension =
 157       registry->enabled_extensions().GetByID(extension_id);
 158   if (!extension)
 159     return;
 160   ExtensionSystem* system = ExtensionSystem::Get(context_);
 161   Mode mode = ShouldBeVerified(*extension);
 162   if (mode >= ContentVerifierDelegate::ENFORCE) {
 163     if (!system->management_policy()->UserMayModifySettings(extension, NULL)) {
 164       LogFailureForPolicyForceInstall(extension_id);
 165       return;
 166     }
 167     system->extension_service()->DisableExtension(extension_id,
 168                                                   Extension::DISABLE_CORRUPTED);
 169     ExtensionPrefs::Get(context_)->IncrementCorruptedDisableCount();
 170     UMA_HISTOGRAM_BOOLEAN("Extensions.CorruptExtensionBecameDisabled", true);
 171     UMA_HISTOGRAM_ENUMERATION("Extensions.CorruptExtensionDisabledReason",
 172                               reason, ContentVerifyJob::FAILURE_REASON_MAX);
 173   } else if (!ContainsKey(would_be_disabled_ids_, extension_id)) {
 174     UMA_HISTOGRAM_BOOLEAN("Extensions.CorruptExtensionWouldBeDisabled", true);
 175     would_be_disabled_ids_.insert(extension_id);
 176   }
 177 }
 178
 179 void ChromeContentVerifierDelegate::LogFailureForPolicyForceInstall(
 180     const std::string& extension_id) {
 181   if (!ContainsKey(corrupt_policy_extensions_, extension_id)) {
 182     corrupt_policy_extensions_.insert(extension_id);
 183     UMA_HISTOGRAM_BOOLEAN("Extensions.CorruptPolicyExtensionWouldBeDisabled",
 184                           true);
 185   }
 186 }
 187
 188 }  // namespace extensions