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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/protector/protected_prefs_watcher.h"
#include "base/base64.h"
#include "base/logging.h"
#include "base/metrics/histogram.h"
#include "base/stringprintf.h"
#include "base/values.h"
#include "chrome/browser/prefs/pref_service.h"
#include "chrome/browser/prefs/pref_set_observer.h"
#include "chrome/browser/prefs/scoped_user_pref_update.h"
#include "chrome/browser/prefs/session_startup_pref.h"
#include "chrome/browser/profiles/profile.h"
#include "chrome/browser/protector/histograms.h"
#include "chrome/browser/protector/protector_service.h"
#include "chrome/common/chrome_notification_types.h"
#include "chrome/common/pref_names.h"
#include "content/public/browser/notification_service.h"
namespace protector {
namespace {
const char kBackupPrefsPrefix[] = "backup.";
// Backup pref names.
const char kBackupHomePage[] = "backup.homepage";
const char kBackupHomePageIsNewTabPage[] = "backup.homepage_is_newtabpage";
const char kBackupShowHomeButton[] = "backup.browser.show_home_button";
const char kBackupRestoreOnStartup[] = "backup.session.restore_on_startup";
const char kBackupURLsToRestoreOnStartup[] =
"backup.session.urls_to_restore_on_startup";
const char kBackupExtensionsIDs[] = "backup.extensions.ids";
const char kBackupSignature[] = "backup._signature";
} // namespace
ProtectedPrefsWatcher::ProtectedPrefsWatcher(Profile* profile)
: is_backup_valid_(true),
profile_(profile) {
// Perform necessary pref migrations before actually starting to observe
// pref changes, otherwise the migration would affect the backup data as well.
EnsurePrefsMigration();
pref_observer_.reset(PrefSetObserver::CreateProtectedPrefSetObserver(
profile->GetPrefs(), this));
UpdateCachedPrefs();
ValidateBackup();
VLOG(1) << "Initialized pref watcher";
}
ProtectedPrefsWatcher::~ProtectedPrefsWatcher() {
}
// static
void ProtectedPrefsWatcher::RegisterUserPrefs(PrefService* prefs) {
prefs->RegisterStringPref(kBackupHomePage, "",
PrefService::UNSYNCABLE_PREF);
prefs->RegisterBooleanPref(kBackupHomePageIsNewTabPage, false,
PrefService::UNSYNCABLE_PREF);
prefs->RegisterBooleanPref(kBackupShowHomeButton, false,
PrefService::UNSYNCABLE_PREF);
prefs->RegisterIntegerPref(kBackupRestoreOnStartup, 0,
PrefService::UNSYNCABLE_PREF);
prefs->RegisterListPref(kBackupURLsToRestoreOnStartup,
PrefService::UNSYNCABLE_PREF);
prefs->RegisterListPref(kBackupExtensionsIDs,
PrefService::UNSYNCABLE_PREF);
prefs->RegisterStringPref(kBackupSignature, "",
PrefService::UNSYNCABLE_PREF);
}
const base::Value* ProtectedPrefsWatcher::GetBackupForPref(
const std::string& path) const {
if (!is_backup_valid_)
return NULL;
std::string backup_path = std::string(kBackupPrefsPrefix) + path;
const PrefService::Preference* backup_pref =
profile_->GetPrefs()->FindPreference(backup_path.c_str());
DCHECK(backup_pref &&
// These do not directly correspond to any real preference.
backup_path != kBackupExtensionsIDs &&
backup_path != kBackupSignature);
return backup_pref->GetValue();
}
void ProtectedPrefsWatcher::Observe(
int type,
const content::NotificationSource& source,
const content::NotificationDetails& details) {
DCHECK(type == chrome::NOTIFICATION_PREF_CHANGED);
const std::string* pref_name = content::Details<std::string>(details).ptr();
DCHECK(pref_name && pref_observer_->IsObserved(*pref_name));
if (UpdateBackupEntry(*pref_name))
UpdateBackupSignature();
}
void ProtectedPrefsWatcher::EnsurePrefsMigration() {
// Force SessionStartupPref migration, if necessary.
SessionStartupPref::GetStartupPref(profile_);
}
bool ProtectedPrefsWatcher::UpdateCachedPrefs() {
// Direct access to the extensions prefs is required becase ExtensionService
// may not yet have been initialized.
ExtensionPrefs::ExtensionIdSet extension_ids =
ExtensionPrefs::GetExtensionsFrom(
profile_->GetPrefs()->GetDictionary(ExtensionPrefs::kExtensionsPref));
if (extension_ids == cached_extension_ids_)
return false;
cached_extension_ids_.swap(extension_ids);
return true;
}
bool ProtectedPrefsWatcher::HasBackup() const {
// TODO(ivankr): as soon as some irreversible change to Preferences happens,
// add a condition that this change has occured as well (otherwise it's
// possible to simply clear the "backup" dictionary to make settings
// unprotected).
return profile_->GetPrefs()->HasPrefPath(kBackupSignature);
}
void ProtectedPrefsWatcher::InitBackup() {
PrefService* prefs = profile_->GetPrefs();
prefs->SetString(kBackupHomePage, prefs->GetString(prefs::kHomePage));
prefs->SetBoolean(kBackupHomePageIsNewTabPage,
prefs->GetBoolean(prefs::kHomePageIsNewTabPage));
prefs->SetBoolean(kBackupShowHomeButton,
prefs->GetBoolean(prefs::kShowHomeButton));
prefs->SetInteger(kBackupRestoreOnStartup,
prefs->GetInteger(prefs::kRestoreOnStartup));
prefs->Set(kBackupURLsToRestoreOnStartup,
*prefs->GetList(prefs::kURLsToRestoreOnStartup));
ListPrefUpdate extension_ids_update(prefs, kBackupExtensionsIDs);
base::ListValue* extension_ids = extension_ids_update.Get();
extension_ids->Clear();
for (ExtensionPrefs::ExtensionIdSet::const_iterator it =
cached_extension_ids_.begin();
it != cached_extension_ids_.end(); ++it) {
extension_ids->Append(base::Value::CreateStringValue(*it));
}
UpdateBackupSignature();
}
bool ProtectedPrefsWatcher::UpdateBackupEntry(const std::string& pref_name) {
PrefService* prefs = profile_->GetPrefs();
if (pref_name == ExtensionPrefs::kExtensionsPref) {
// For changes in extension dictionary, do nothing if the IDs list remained
// the same.
if (!UpdateCachedPrefs())
return false;
ListPrefUpdate extension_ids_update(prefs, kBackupExtensionsIDs);
base::ListValue* extension_ids = extension_ids_update.Get();
extension_ids->Clear();
for (ExtensionPrefs::ExtensionIdSet::const_iterator it =
cached_extension_ids_.begin();
it != cached_extension_ids_.end(); ++it) {
extension_ids->Append(base::Value::CreateStringValue(*it));
}
} else if (pref_name == prefs::kHomePage) {
prefs->SetString(kBackupHomePage, prefs->GetString(prefs::kHomePage));
} else if (pref_name == prefs::kHomePageIsNewTabPage) {
prefs->SetBoolean(kBackupHomePageIsNewTabPage,
prefs->GetBoolean(prefs::kHomePageIsNewTabPage));
} else if (pref_name == prefs::kShowHomeButton) {
prefs->SetBoolean(kBackupShowHomeButton,
prefs->GetBoolean(prefs::kShowHomeButton));
} else if (pref_name == prefs::kRestoreOnStartup) {
prefs->SetInteger(kBackupRestoreOnStartup,
prefs->GetInteger(prefs::kRestoreOnStartup));
} else if (pref_name == prefs::kURLsToRestoreOnStartup) {
prefs->Set(kBackupURLsToRestoreOnStartup,
*prefs->GetList(prefs::kURLsToRestoreOnStartup));
} else {
NOTREACHED();
return false;
}
VLOG(1) << "Updated backup entry for: " << pref_name;
return true;
}
void ProtectedPrefsWatcher::UpdateBackupSignature() {
PrefService* prefs = profile_->GetPrefs();
std::string signed_data = GetSignatureData(prefs);
DCHECK(!signed_data.empty());
std::string signature = SignSetting(signed_data);
DCHECK(!signature.empty());
std::string signature_base64;
if (!base::Base64Encode(signature, &signature_base64))
NOTREACHED();
prefs->SetString(kBackupSignature, signature_base64);
// Schedule disk write on FILE thread as soon as possible.
prefs->CommitPendingWrite();
VLOG(1) << "Updated backup signature";
}
bool ProtectedPrefsWatcher::IsSignatureValid() const {
DCHECK(HasBackup());
PrefService* prefs = profile_->GetPrefs();
std::string signed_data = GetSignatureData(prefs);
DCHECK(!signed_data.empty());
std::string signature;
if (!base::Base64Decode(prefs->GetString(kBackupSignature), &signature))
return false;
return IsSettingValid(signed_data, signature);
}
void ProtectedPrefsWatcher::ValidateBackup() {
if (!HasBackup()) {
// Create initial backup entries and sign them.
InitBackup();
UMA_HISTOGRAM_ENUMERATION(
kProtectorHistogramPrefs,
kProtectorErrorValueValidZero,
kProtectorErrorCount);
} else if (IsSignatureValid()) {
UMA_HISTOGRAM_ENUMERATION(
kProtectorHistogramPrefs,
kProtectorErrorValueValid,
kProtectorErrorCount);
} else {
LOG(WARNING) << "Invalid backup signature";
// Further changes to protected prefs will overwrite the signature.
is_backup_valid_ = false;
UMA_HISTOGRAM_ENUMERATION(
kProtectorHistogramPrefs,
kProtectorErrorBackupInvalid,
kProtectorErrorCount);
}
}
std::string ProtectedPrefsWatcher::GetSignatureData(PrefService* prefs) const {
// std::stringstream data;
std::string data = base::StringPrintf(
"%s|%d|%d|%d",
prefs->GetString(kBackupHomePage).c_str(),
prefs->GetBoolean(kBackupHomePageIsNewTabPage) ? 1 : 0,
prefs->GetBoolean(kBackupShowHomeButton) ? 1 : 0,
prefs->GetInteger(kBackupRestoreOnStartup));
const base::ListValue* startup_urls =
prefs->GetList(kBackupURLsToRestoreOnStartup);
for (base::ListValue::const_iterator it = startup_urls->begin();
it != startup_urls->end(); ++it) {
std::string url;
if (!(*it)->GetAsString(&url))
NOTREACHED();
base::StringAppendF(&data, "|%s", url.c_str());
}
// These are safe to use becase they are always up-to-date and returned in
// a consistent (sorted) order.
for (ExtensionPrefs::ExtensionIdSet::const_iterator it =
cached_extension_ids_.begin();
it != cached_extension_ids_.end(); ++it) {
base::StringAppendF(&data, "|%s", it->c_str());
}
return data;
}
} // namespace protector
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