Move Olm account to IndexedDB

src/crypto/OlmDevice.js

@@ -74,13 +74,15 @@ function checkPayloadLength(payloadString) {
  * @alias module:crypto/OlmDevice
  *
  * @param {Object} sessionStore A store to be used for data in end-to-end
- *    crypto
+ *    crypto. This is deprecated and being replaced by cryptoStore.
+ * @param {Object} cryptoStore A store for crypto data
  *
  * @property {string} deviceCurve25519Key   Curve25519 key for the account
  * @property {string} deviceEd25519Key      Ed25519 key for the account
  */
-function OlmDevice(sessionStore) {
+function OlmDevice(sessionStore, cryptoStore) {
     this._sessionStore = sessionStore;
+    this._cryptoStore = cryptoStore;
     this._pickleKey = "DEFAULT_KEY";
 
     // don't know these until we load the account from storage in init()
@@ -124,7 +126,9 @@ OlmDevice.prototype.init = async function() {
     let e2eKeys;
     const account = new Olm.Account();
     try {
-        _initialise_account(this._sessionStore, this._pickleKey, account);
+        await _initialise_account(
+            this._sessionStore, this._cryptoStore, this._pickleKey, account,
+        );
         e2eKeys = JSON.parse(account.identity_keys());
 
         this._maxOneTimeKeys = account.max_number_of_one_time_keys();
@@ -137,16 +141,29 @@ OlmDevice.prototype.init = async function() {
 };
 
 
-function _initialise_account(sessionStore, pickleKey, account) {
-    const e2eAccount = sessionStore.getEndToEndAccount();
-    if (e2eAccount !== null) {
-        account.unpickle(pickleKey, e2eAccount);
-        return;
-    }
+async function _initialise_account(sessionStore, cryptoStore, pickleKey, account) {
+    let removeFromSessionStore = false;
+    await cryptoStore.endToEndAccountTransaction((accountData, save) => {
+        if (accountData !== null) {
+            account.unpickle(pickleKey, accountData);
+        } else {
+            // Migrate from sessionStore
+            accountData = sessionStore.getEndToEndAccount();
+            if (accountData !== null) {
+                removeFromSessionStore = true;
+                account.unpickle(pickleKey, accountData);
+            } else {
+                account.create();
+                accountData = account.pickle(pickleKey);
+            }
+            save(accountData);
+        }
+    });
 
-    account.create();
-    const pickled = account.pickle(pickleKey);
-    sessionStore.storeEndToEndAccount(pickled);
+    // only remove this once it's safely saved to the crypto store
+    if (removeFromSessionStore) {
+        sessionStore.removeEndToEndAccount();
+    }
 }
 
 /**
@@ -158,21 +175,35 @@ OlmDevice.getOlmVersion = function() {
 
 
 /**
- * extract our OlmAccount from the session store and call the given function
+ * extract our OlmAccount from the crypto store and call the given function
+ * with the account object and a 'save' function which returns a promise.
+ * The function will not be awaited upon and the save function must be
+ * called before the function returns, or not at all.
  *
  * @param {function} func
  * @return {object} result of func
  * @private
  */
-OlmDevice.prototype._getAccount = function(func) {
-    const account = new Olm.Account();
-    try {
-        const pickledAccount = this._sessionStore.getEndToEndAccount();
-        account.unpickle(this._pickleKey, pickledAccount);
-        return func(account);
-    } finally {
-        account.free();
-    }
+OlmDevice.prototype._getAccount = async function(func) {
+    let result;
+
+    await this._cryptoStore.endToEndAccountTransaction((accountData, save) => {
+        // Olm has a limited heap size so we must tightly control the number of
+        // Olm account objects in existence at any given time: once created, it
+        // must be destroyed again before we await.
+        const account = new Olm.Account();
+        try {
+            account.unpickle(this._pickleKey, accountData);
+
+            result = func(account, () => {
+                const pickledAccount = account.pickle(this._pickleKey);
+                return save(pickledAccount);
+            });
+        } finally {
+            account.free();
+        }
+    });
+    return result;
 };
 
 
@@ -182,9 +213,9 @@ OlmDevice.prototype._getAccount = function(func) {
  * @param {OlmAccount} account
  * @private
  */
-OlmDevice.prototype._saveAccount = function(account) {
+OlmDevice.prototype._saveAccount = async function(account) {
     const pickledAccount = account.pickle(this._pickleKey);
-    this._sessionStore.storeEndToEndAccount(pickledAccount);
+    await this._cryptoStore.storeEndToEndAccount(pickledAccount);
 };
 
 
@@ -250,7 +281,7 @@ OlmDevice.prototype._getUtility = function(func) {
  * @return {Promise<string>} base64-encoded signature
  */
 OlmDevice.prototype.sign = async function(message) {
-    return this._getAccount(function(account) {
+    return await this._getAccount(function(account) {
         return account.sign(message);
     });
 };
@@ -263,7 +294,7 @@ OlmDevice.prototype.sign = async function(message) {
  * key.
  */
 OlmDevice.prototype.getOneTimeKeys = async function() {
-    return this._getAccount(function(account) {
+    return await this._getAccount(function(account) {
         return JSON.parse(account.one_time_keys());
     });
 };
@@ -282,23 +313,22 @@ OlmDevice.prototype.maxNumberOfOneTimeKeys = function() {
  * Marks all of the one-time keys as published.
  */
 OlmDevice.prototype.markKeysAsPublished = async function() {
-    const self = this;
-    this._getAccount(function(account) {
+    await this._getAccount(function(account, save) {
         account.mark_keys_as_published();
-        self._saveAccount(account);
+        return save();
     });
 };
 
 /**
  * Generate some new one-time keys
  *
  * @param {number} numKeys number of keys to generate
+ * @return {Promise} Resolved once the account is saved back having generated the keys
  */
 OlmDevice.prototype.generateOneTimeKeys = async function(numKeys) {
-    const self = this;
-    this._getAccount(function(account) {
+    return this._getAccount(function(account, save) {
         account.generate_one_time_keys(numKeys);
-        self._saveAccount(account);
+        return save();
     });
 };
 
@@ -315,11 +345,12 @@ OlmDevice.prototype.createOutboundSession = async function(
     theirIdentityKey, theirOneTimeKey,
 ) {
     const self = this;
-    return this._getAccount(function(account) {
+    return await this._getAccount(async function(account, save) {
         const session = new Olm.Session();
         try {
             session.create_outbound(account, theirIdentityKey, theirOneTimeKey);
-            self._saveSession(theirIdentityKey, session);
+            await save();
+            await self._saveSession(theirIdentityKey, session);
             return session.session_id();
         } finally {
             session.free();
@@ -349,12 +380,12 @@ OlmDevice.prototype.createInboundSession = async function(
     }
 
     const self = this;
-    return this._getAccount(function(account) {
+    return await this._getAccount(async function(account, save) {
         const session = new Olm.Session();
         try {
             session.create_inbound_from(account, theirDeviceIdentityKey, ciphertext);
             account.remove_one_time_keys(session);
-            self._saveAccount(account);
+            await save();
 
             const payloadString = session.decrypt(message_type, ciphertext);
 

src/crypto/index.js

@@ -67,7 +67,7 @@ function Crypto(baseApis, sessionStore, userId, deviceId,
     this._clientStore = clientStore;
     this._cryptoStore = cryptoStore;
 
-    this._olmDevice = new OlmDevice(sessionStore);
+    this._olmDevice = new OlmDevice(sessionStore, cryptoStore);
     this._deviceList = new DeviceList(baseApis, sessionStore, this._olmDevice);
 
     // the last time we did a check for the number of one-time-keys on the

src/crypto/store/indexeddb-crypto-store-backend.js

@@ -1,7 +1,7 @@
 import Promise from 'bluebird';
 import utils from '../../utils';
 
-export const VERSION = 1;
+export const VERSION = 2;
 
 /**
  * Implementation of a CryptoStore which is backed by an existing
@@ -257,6 +257,39 @@ export class Backend {
         };
         return promiseifyTxn(txn);
     }
+
+    /**
+     * Load the end to end account for the logged-in user. Once the account
+     * is retrieved, the given function is executed and passed the base64
+     * encoded account string and a method for saving the account string
+     * back to the database. This allows the account to be read and writen
+     * atomically.
+     * @param {func} func Function called with the account data and a save function
+     * @return {Promise} Resolves with the return value of the function once
+     *     the transaction is complete (ie. once data is written back if the
+     *     save function is called.
+     */
+    endToEndAccountTransaction(func) {
+        const txn = this._db.transaction("account", "readwrite");
+        const objectStore = txn.objectStore("account");
+
+        const txnPromise = promiseifyTxn(txn);
+
+        const getReq = objectStore.get("-");
+        let result;
+        getReq.onsuccess = function() {
+            result = func(
+                getReq.result || null,
+                (newData) => {
+                    objectStore.put(newData, "-");
+                    return txnPromise;
+                },
+            );
+        };
+        return txnPromise.then(() => {
+            return result;
+        });
+    }
 }
 
 export function upgradeDatabase(db, oldVersion) {
@@ -267,6 +300,9 @@ export function upgradeDatabase(db, oldVersion) {
     if (oldVersion < 1) { // The database did not previously exist.
         createDatabase(db);
     }
+    if (oldVersion < 2) {
+        createV2Tables(db);
+    }
     // Expand as needed.
 }
 
@@ -283,6 +319,10 @@ function createDatabase(db) {
     outgoingRoomKeyRequestsStore.createIndex("state", "state");
 }
 
+function createV2Tables(db) {
+    db.createObjectStore("account");
+}
+
 function promiseifyTxn(txn) {
     return new Promise((resolve, reject) => {
         txn.oncomplete = resolve;

src/crypto/store/indexeddb-crypto-store.js

@@ -16,6 +16,7 @@ limitations under the License.
 
 import Promise from 'bluebird';
 
+import LocalStorageCryptoStore from './localStorage-crypto-store';
 import MemoryCryptoStore from './memory-crypto-store';
 import * as IndexedDBCryptoStoreBackend from './indexeddb-crypto-store-backend';
 
@@ -93,7 +94,12 @@ export default class IndexedDBCryptoStore {
         }).catch((e) => {
             console.warn(
                 `unable to connect to indexeddb ${this._dbName}` +
-                    `: falling back to in-memory store: ${e}`,
+                    `: falling back to localStorage store: ${e}`,
+            );
+            return new LocalStorageCryptoStore();
+        }).catch((e) => {
+            console.warn(
+                `unable to open localStorage: falling back to in-memory store: ${e}`,
             );
             return new MemoryCryptoStore();
         });
@@ -220,4 +226,21 @@ export default class IndexedDBCryptoStore {
             return backend.deleteOutgoingRoomKeyRequest(requestId, expectedState);
         });
     }
+
+    /**
+     * Load the end to end account for the logged-in user. Once the account
+     * is retrieved, the given function is executed and passed the base64
+     * encoded account string and a method for saving the account string
+     * back to the database. This allows the account to be read and writen
+     * atomically.
+     * @param {func} func Function called with the account data and a save function
+     * @return {Promise} Resolves with the return value of the function once
+     *     the transaction is complete (ie. once data is written back if the
+     *     save function is called.
+     */
+    endToEndAccountTransaction(func) {
+        return this._connect().then((backend) => {
+            return backend.endToEndAccountTransaction(func);
+        });
+    }
 }

src/crypto/store/localStorage-crypto-store.js

@@ -0,0 +1,58 @@
+/*
+Copyright 2017 New Vector Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import Promise from 'bluebird';
+import MemoryCryptoStore from './memory-crypto-store.js';
+
+/**
+ * Internal module. Partial localStorage backed storage for e2e.
+ * This is not a full crypto store, just the in-memory store with
+ * some things backed by localStorage. It exists because indexedDB
+ * is broken in Firefox private mode or set to, "will not remember
+ * history".
+ *
+ * @module
+ */
+
+const E2E_PREFIX = "crypto.";
+const KEY_END_TO_END_ACCOUNT = E2E_PREFIX + "account";
+
+/**
+ * @implements {module:crypto/store/base~CryptoStore}
+ */
+export default class LocalStorageCryptoStore extends MemoryCryptoStore {
+    constructor() {
+        super();
+        this.store = global.localStorage;
+    }
+
+    /**
+     * Delete all data from this store.
+     *
+     * @returns {Promise} Promise which resolves when the store has been cleared.
+     */
+    deleteAllData() {
+        this.store.removeItem(KEY_END_TO_END_ACCOUNT);
+        return Promise.resolve();
+    }
+
+    endToEndAccountTransaction(func) {
+        const account = this.store.getItem(KEY_END_TO_END_ACCOUNT);
+        return Promise.resolve(func(account, (newData) => {
+            this.store.setItem(KEY_END_TO_END_ACCOUNT, newData);
+        }));
+    }
+}