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// Copyright 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 <string>
#include <vector>
#include "base/compiler_specific.h"
#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "base/threading/thread_checker.h"
#include "base/time/time.h"
#include "sync/base/sync_export.h"
#include "sync/internal_api/public/sync_encryption_handler.h"
#include "sync/syncable/nigori_handler.h"
#include "sync/util/cryptographer.h"
namespace syncer {
class Encryptor;
struct UserShare;
class WriteNode;
class WriteTransaction;
// Sync encryption handler implementation.
// This class acts as the respository of all sync encryption state, and handles
// encryption related changes/queries coming from both the chrome side and
// the sync side (via NigoriHandler). It is capable of modifying all sync data
// (re-encryption), updating the encrypted types, changing the encryption keys,
// and creating/receiving nigori node updates.
// The class should live as long as the directory itself in order to ensure
// any data read/written is properly decrypted/encrypted.
// Note: See sync_encryption_handler.h for a description of the chrome visible
// methods and what they do, and nigori_handler.h for a description of the
// sync methods.
// All methods are non-thread-safe and should only be called from the sync
// thread unless explicitly noted otherwise.
class SYNC_EXPORT SyncEncryptionHandlerImpl : public SyncEncryptionHandler,
public syncable::NigoriHandler {
UserShare* user_share,
Encryptor* encryptor,
const std::string& restored_key_for_bootstrapping,
const std::string& restored_keystore_key_for_bootstrapping);
~SyncEncryptionHandlerImpl() override;
// SyncEncryptionHandler implementation.
void AddObserver(Observer* observer) override;
void RemoveObserver(Observer* observer) override;
void Init() override;
void SetEncryptionPassphrase(const std::string& passphrase,
bool is_explicit) override;
void SetDecryptionPassphrase(const std::string& passphrase) override;
void EnableEncryptEverything() override;
bool IsEncryptEverythingEnabled() const override;
PassphraseType GetPassphraseType() const override;
// NigoriHandler implementation.
// Note: all methods are invoked while the caller holds a transaction.
void ApplyNigoriUpdate(const sync_pb::NigoriSpecifics& nigori,
syncable::BaseTransaction* const trans) override;
void UpdateNigoriFromEncryptedTypes(
sync_pb::NigoriSpecifics* nigori,
syncable::BaseTransaction* const trans) const override;
bool NeedKeystoreKey(syncable::BaseTransaction* const trans) const override;
bool SetKeystoreKeys(
const google::protobuf::RepeatedPtrField<google::protobuf::string>& keys,
syncable::BaseTransaction* const trans) override;
// Can be called from any thread.
ModelTypeSet GetEncryptedTypes(
syncable::BaseTransaction* const trans) const override;
// Unsafe getters. Use only if sync is not up and running and there is no risk
// of other threads calling this.
Cryptographer* GetCryptographerUnsafe();
ModelTypeSet GetEncryptedTypesUnsafe();
bool MigratedToKeystore();
base::Time migration_time() const;
base::Time custom_passphrase_time() const;
// Restore a saved nigori obtained from OnLocalSetPassphraseEncryption.
// Writes the nigori to the Directory and updates the Cryptographer.
void RestoreNigori(const SyncEncryptionHandler::NigoriState& nigori_state);
friend class SyncEncryptionHandlerImplTest;
// Container for members that require thread safety protection. All members
// that can be accessed from more than one thread should be held here and
// accessed via UnlockVault(..) and UnlockVaultMutable(..), which enforce
// that a transaction is held.
struct Vault {
Vault(Encryptor* encryptor, ModelTypeSet encrypted_types);
// Sync's cryptographer. Used for encrypting and decrypting sync data.
Cryptographer cryptographer;
// The set of types that require encryption.
ModelTypeSet encrypted_types;
// Iterate over all encrypted types ensuring each entry is properly encrypted.
void ReEncryptEverything(WriteTransaction* trans);
// Updates internal and cryptographer state.
// Assumes |nigori| is already present in the Sync Directory.
// Returns true on success, false if |nigori| was incompatible, and the
// nigori node must be corrected.
// Note: must be called from within a transaction.
bool ApplyNigoriUpdateImpl(const sync_pb::NigoriSpecifics& nigori,
syncable::BaseTransaction* const trans);
// Wrapper around WriteEncryptionStateToNigori that creates a new write
// transaction.
void RewriteNigori();
// Write the current encryption state into the nigori node. This includes
// the encrypted types/encrypt everything state, as well as the keybag/
// explicit passphrase state (if the cryptographer is ready).
void WriteEncryptionStateToNigori(WriteTransaction* trans);
// Updates local encrypted types from |nigori|.
// Returns true if the local set of encrypted types either matched or was
// a subset of that in |nigori|. Returns false if the local state already
// had stricter encryption than |nigori|, and the nigori node needs to be
// updated with the newer encryption state.
// Note: must be called from within a transaction.
bool UpdateEncryptedTypesFromNigori(
const sync_pb::NigoriSpecifics& nigori,
syncable::BaseTransaction* const trans);
// TODO(zea): make these public and have them replace SetEncryptionPassphrase
// and SetDecryptionPassphrase.
// Helper methods for handling passphrases once keystore migration has taken
// place.
// Sets a new custom passphrase. Should only be called if a custom passphrase
// is not already set.
// Triggers OnPassphraseAccepted on success, OnPassphraseRequired if a custom
// passphrase already existed.
void SetCustomPassphrase(const std::string& passphrase,
WriteTransaction* trans,
WriteNode* nigori_node);
// Decrypt the encryption keybag using a user provided passphrase.
// Should only be called if the current passphrase is a frozen implicit
// passphrase or a custom passphrase.
// Triggers OnPassphraseAccepted on success, OnPassphraseRequired on failure.
void DecryptPendingKeysWithExplicitPassphrase(const std::string& passphrase,
WriteTransaction* trans,
WriteNode* nigori_node);
// The final step of SetEncryptionPassphrase and SetDecryptionPassphrase that
// notifies observers of the result of the set passphrase operation, updates
// the nigori node, and does re-encryption.
// |success|: true if the operation was successful and false otherwise. If
// success == false, we send an OnPassphraseRequired notification.
// |bootstrap_token|: used to inform observers if the cryptographer's
// bootstrap token was updated.
// |is_explicit|: used to differentiate between a custom passphrase (true) and
// a GAIA passphrase that is implicitly used for encryption
// (false).
// |trans| and |nigori_node|: used to access data in the cryptographer.
void FinishSetPassphrase(bool success,
const std::string& bootstrap_token,
WriteTransaction* trans,
WriteNode* nigori_node);
// Merges the given set of encrypted types with the existing set and emits a
// notification if necessary.
// Note: must be called from within a transaction.
void MergeEncryptedTypes(ModelTypeSet new_encrypted_types,
syncable::BaseTransaction* const trans);
// Helper methods for ensuring transactions are held when accessing
// |vault_unsafe_|.
Vault* UnlockVaultMutable(syncable::BaseTransaction* const trans);
const Vault& UnlockVault(syncable::BaseTransaction* const trans) const;
// Helper method for determining if migration of a nigori node should be
// triggered or not.
// Conditions for triggering migration:
// 1. Cryptographer has no pending keys
// 2. Nigori node isn't already properly migrated or we need to rotate keys.
// 3. Keystore key is available.
// Note: if the nigori node is migrated but has an invalid state, will return
// true (e.g. node has KEYSTORE_PASSPHRASE, local is CUSTOM_PASSPHRASE).
bool ShouldTriggerMigration(const sync_pb::NigoriSpecifics& nigori,
const Cryptographer& cryptographer) const;
// Performs the actual migration of the |nigori_node| to support keystore
// encryption iff ShouldTriggerMigration(..) returns true.
bool AttemptToMigrateNigoriToKeystore(WriteTransaction* trans,
WriteNode* nigori_node);
// Fill |encrypted_blob| with the keystore decryptor token if
// |encrypted_blob|'s contents didn't already contain the key.
// The keystore decryptor token is the serialized current default encryption
// key, encrypted with the keystore key.
bool GetKeystoreDecryptor(
const Cryptographer& cryptographer,
const std::string& keystore_key,
sync_pb::EncryptedData* encrypted_blob);
// Helper method for installing the keys encrypted in |encryption_keybag|
// into |cryptographer|.
// Returns true on success, false if we were unable to install the keybag.
// Will not update the default key.
bool AttemptToInstallKeybag(const sync_pb::EncryptedData& keybag,
bool update_default,
Cryptographer* cryptographer);
// Helper method for decrypting pending keys with the keystore bootstrap.
// If successful, the default will become the key encrypted in the keystore
// bootstrap, and will return true. Else will return false.
bool DecryptPendingKeysWithKeystoreKey(
const std::string& keystore_key,
const sync_pb::EncryptedData& keystore_bootstrap,
Cryptographer* cryptographer);
// Helper to enable encrypt everything, notifying observers if necessary.
// Will not perform re-encryption.
void EnableEncryptEverythingImpl(syncable::BaseTransaction* const trans);
// If an explicit passphrase is in use, returns the time at which it was set
// (if known). Else return base::Time().
base::Time GetExplicitPassphraseTime() const;
// Notify observers when a custom passphrase is set by this device.
void NotifyObserversOfLocalCustomPassphrase(WriteTransaction* trans);
base::ThreadChecker thread_checker_;
base::ObserverList<SyncEncryptionHandler::Observer> observers_;
// The current user share (for creating transactions).
UserShare* user_share_;
// Container for all data that can be accessed from multiple threads. Do not
// access this object directly. Instead access it via UnlockVault(..) and
// UnlockVaultMutable(..).
Vault vault_unsafe_;
// Sync encryption state that is only modified and accessed from the sync
// thread.
// Whether all current and future types should be encrypted.
bool encrypt_everything_;
// The current state of the passphrase required to decrypt the encryption
// keys stored in the nigori node.
PassphraseType passphrase_type_;
// The current keystore key provided by the server.
std::string keystore_key_;
// The set of old keystore keys. Every time a key rotation occurs, the server
// sends down all previous keystore keys as well as the new key. We preserve
// the old keys so that when we re-encrypt we can ensure they're all added to
// the keybag (and to detect that a key rotation has occurred).
std::vector<std::string> old_keystore_keys_;
// The number of times we've automatically (i.e. not via SetPassphrase or
// conflict resolver) updated the nigori's encryption keys in this chrome
// instantiation.
int nigori_overwrite_count_;
// The time the nigori was migrated to support keystore encryption.
base::Time migration_time_;
// The time the custom passphrase was set for this account. Not valid
// if there is no custom passphrase or the custom passphrase was set
// before support for this field was added.
base::Time custom_passphrase_time_;
base::WeakPtrFactory<SyncEncryptionHandlerImpl> weak_ptr_factory_;
} // namespace syncer