diff options
Diffstat (limited to 'services/fxaccounts/FxAccountsPairing.sys.mjs')
| -rw-r--r-- | services/fxaccounts/FxAccountsPairing.sys.mjs | 510 |
1 files changed, 510 insertions, 0 deletions
diff --git a/services/fxaccounts/FxAccountsPairing.sys.mjs b/services/fxaccounts/FxAccountsPairing.sys.mjs new file mode 100644 index 0000000000..7a0aec2217 --- /dev/null +++ b/services/fxaccounts/FxAccountsPairing.sys.mjs @@ -0,0 +1,510 @@ +// This Source Code Form is subject to the terms of the Mozilla Public +// License, v. 2.0. If a copy of the MPL was not distributed with this +// file, You can obtain one at http://mozilla.org/MPL/2.0/. + +const { + log, + PREF_REMOTE_PAIRING_URI, + COMMAND_PAIR_SUPP_METADATA, + COMMAND_PAIR_AUTHORIZE, + COMMAND_PAIR_DECLINE, + COMMAND_PAIR_HEARTBEAT, + COMMAND_PAIR_COMPLETE, +} = ChromeUtils.import("resource://gre/modules/FxAccountsCommon.js"); +import { + getFxAccountsSingleton, + FxAccounts, +} from "resource://gre/modules/FxAccounts.sys.mjs"; + +const fxAccounts = getFxAccountsSingleton(); +import { setTimeout, clearTimeout } from "resource://gre/modules/Timer.sys.mjs"; + +ChromeUtils.importESModule("resource://services-common/utils.sys.mjs"); +const lazy = {}; +ChromeUtils.defineESModuleGetters(lazy, { + FxAccountsPairingChannel: + "resource://gre/modules/FxAccountsPairingChannel.sys.mjs", + + Weave: "resource://services-sync/main.sys.mjs", + jwcrypto: "resource://services-crypto/jwcrypto.sys.mjs", +}); + +const PAIRING_REDIRECT_URI = "urn:ietf:wg:oauth:2.0:oob:pair-auth-webchannel"; +// A pairing flow is not tied to a specific browser window, can also finish in +// various ways and subsequently might leak a Web Socket, so just in case we +// time out and free-up the resources after a specified amount of time. +const FLOW_TIMEOUT_MS = 15 * 60 * 1000; // 15 minutes. + +class PairingStateMachine { + constructor(emitter) { + this._emitter = emitter; + this._transition(SuppConnectionPending); + } + + get currentState() { + return this._currentState; + } + + _transition(StateCtor, ...args) { + const state = new StateCtor(this, ...args); + this._currentState = state; + } + + assertState(RequiredStates, messagePrefix = null) { + if (!(RequiredStates instanceof Array)) { + RequiredStates = [RequiredStates]; + } + if ( + !RequiredStates.some( + RequiredState => this._currentState instanceof RequiredState + ) + ) { + const msg = `${ + messagePrefix ? `${messagePrefix}. ` : "" + }Valid expected states: ${RequiredStates.map(({ name }) => name).join( + ", " + )}. Current state: ${this._currentState.label}.`; + throw new Error(msg); + } + } +} + +/** + * The pairing flow can be modeled by a finite state machine: + * We start by connecting to a WebSocket channel (SuppConnectionPending). + * Then the other party connects and requests some metadata from us (PendingConfirmations). + * A confirmation happens locally first (PendingRemoteConfirmation) + * or the oppposite (PendingLocalConfirmation). + * Any side can decline this confirmation (Aborted). + * Once both sides have confirmed, the pairing flow is finished (Completed). + * During this flow errors can happen and should be handled (Errored). + */ +class State { + constructor(stateMachine, ...args) { + this._transition = (...args) => stateMachine._transition(...args); + this._notify = (...args) => stateMachine._emitter.emit(...args); + this.init(...args); + } + + init() { + /* Does nothing by default but can be re-implemented. */ + } + + get label() { + return this.constructor.name; + } + + hasErrored(error) { + this._notify("view:Error", error); + this._transition(Errored, error); + } + + hasAborted() { + this._transition(Aborted); + } +} +class SuppConnectionPending extends State { + suppConnected(sender, oauthOptions) { + this._transition(PendingConfirmations, sender, oauthOptions); + } +} +class PendingConfirmationsState extends State { + localConfirmed() { + throw new Error("Subclasses must implement this method."); + } + remoteConfirmed() { + throw new Error("Subclasses must implement this method."); + } +} +class PendingConfirmations extends PendingConfirmationsState { + init(sender, oauthOptions) { + this.sender = sender; + this.oauthOptions = oauthOptions; + } + + localConfirmed() { + this._transition(PendingRemoteConfirmation); + } + + remoteConfirmed() { + this._transition(PendingLocalConfirmation, this.sender, this.oauthOptions); + } +} +class PendingLocalConfirmation extends PendingConfirmationsState { + init(sender, oauthOptions) { + this.sender = sender; + this.oauthOptions = oauthOptions; + } + + localConfirmed() { + this._transition(Completed); + } + + remoteConfirmed() { + throw new Error( + "Insane state! Remote has already been confirmed at this point." + ); + } +} +class PendingRemoteConfirmation extends PendingConfirmationsState { + localConfirmed() { + throw new Error( + "Insane state! Local has already been confirmed at this point." + ); + } + + remoteConfirmed() { + this._transition(Completed); + } +} +class Completed extends State {} +class Aborted extends State {} +class Errored extends State { + init(error) { + this.error = error; + } +} + +const flows = new Map(); + +export class FxAccountsPairingFlow { + static get(channelId) { + return flows.get(channelId); + } + + static finalizeAll() { + for (const flow of flows) { + flow.finalize(); + } + } + + static async start(options) { + const { emitter } = options; + const fxaConfig = options.fxaConfig || FxAccounts.config; + const fxa = options.fxAccounts || fxAccounts; + const weave = options.weave || lazy.Weave; + const flowTimeout = options.flowTimeout || FLOW_TIMEOUT_MS; + + const contentPairingURI = await fxaConfig.promisePairingURI(); + const wsUri = Services.urlFormatter.formatURLPref(PREF_REMOTE_PAIRING_URI); + const pairingChannel = + options.pairingChannel || + (await lazy.FxAccountsPairingChannel.create(wsUri)); + const { channelId, channelKey } = pairingChannel; + const channelKeyB64 = ChromeUtils.base64URLEncode(channelKey, { + pad: false, + }); + const pairingFlow = new FxAccountsPairingFlow({ + channelId, + pairingChannel, + emitter, + fxa, + fxaConfig, + flowTimeout, + weave, + }); + flows.set(channelId, pairingFlow); + + return `${contentPairingURI}#channel_id=${channelId}&channel_key=${channelKeyB64}`; + } + + constructor(options) { + this._channelId = options.channelId; + this._pairingChannel = options.pairingChannel; + this._emitter = options.emitter; + this._fxa = options.fxa; + this._fxai = options.fxai || this._fxa._internal; + this._fxaConfig = options.fxaConfig; + this._weave = options.weave; + this._stateMachine = new PairingStateMachine(this._emitter); + this._setupListeners(); + this._flowTimeoutId = setTimeout( + () => this._onFlowTimeout(), + options.flowTimeout + ); + } + + _onFlowTimeout() { + log.warn(`The pairing flow ${this._channelId} timed out.`); + this._onError(new Error("Timeout")); + this.finalize(); + } + + _closeChannel() { + if (!this._closed && !this._pairingChannel.closed) { + this._pairingChannel.close(); + this._closed = true; + } + } + + finalize() { + this._closeChannel(); + clearTimeout(this._flowTimeoutId); + // Free up resources and let the GC do its thing. + flows.delete(this._channelId); + } + + _setupListeners() { + this._pairingChannel.addEventListener( + "message", + ({ detail: { sender, data } }) => + this.onPairingChannelMessage(sender, data) + ); + this._pairingChannel.addEventListener("error", event => + this._onPairingChannelError(event.detail.error) + ); + this._emitter.on("view:Closed", () => this.onPrefViewClosed()); + } + + _onAbort() { + this._stateMachine.currentState.hasAborted(); + this.finalize(); + } + + _onError(error) { + this._stateMachine.currentState.hasErrored(error); + this._closeChannel(); + } + + _onPairingChannelError(error) { + log.error("Pairing channel error", error); + this._onError(error); + } + + // Any non-falsy returned value is sent back through WebChannel. + async onWebChannelMessage(command) { + const stateMachine = this._stateMachine; + const curState = stateMachine.currentState; + try { + switch (command) { + case COMMAND_PAIR_SUPP_METADATA: + stateMachine.assertState( + [PendingConfirmations, PendingLocalConfirmation], + `Wrong state for ${command}` + ); + const { + ua, + city, + region, + country, + remote: ipAddress, + } = curState.sender; + return { ua, city, region, country, ipAddress }; + case COMMAND_PAIR_AUTHORIZE: + stateMachine.assertState( + [PendingConfirmations, PendingLocalConfirmation], + `Wrong state for ${command}` + ); + const { + client_id, + state, + scope, + code_challenge, + code_challenge_method, + keys_jwk, + } = curState.oauthOptions; + const authorizeParams = { + client_id, + access_type: "offline", + state, + scope, + code_challenge, + code_challenge_method, + keys_jwk, + }; + const codeAndState = await this._authorizeOAuthCode(authorizeParams); + if (codeAndState.state != state) { + throw new Error(`OAuth state mismatch`); + } + await this._pairingChannel.send({ + message: "pair:auth:authorize", + data: { + ...codeAndState, + }, + }); + curState.localConfirmed(); + break; + case COMMAND_PAIR_DECLINE: + this._onAbort(); + break; + case COMMAND_PAIR_HEARTBEAT: + if (curState instanceof Errored || this._pairingChannel.closed) { + return { err: curState.error.message || "Pairing channel closed" }; + } + const suppAuthorized = !( + curState instanceof PendingConfirmations || + curState instanceof PendingRemoteConfirmation + ); + return { suppAuthorized }; + case COMMAND_PAIR_COMPLETE: + this.finalize(); + break; + default: + throw new Error(`Received unknown WebChannel command: ${command}`); + } + } catch (e) { + log.error(e); + curState.hasErrored(e); + } + return {}; + } + + async onPairingChannelMessage(sender, payload) { + const { message } = payload; + const stateMachine = this._stateMachine; + const curState = stateMachine.currentState; + try { + switch (message) { + case "pair:supp:request": + stateMachine.assertState( + SuppConnectionPending, + `Wrong state for ${message}` + ); + const oauthUri = await this._fxaConfig.promiseOAuthURI(); + const { uid, email, avatar, displayName } = + await this._fxa.getSignedInUser(); + const deviceName = this._weave.Service.clientsEngine.localName; + await this._pairingChannel.send({ + message: "pair:auth:metadata", + data: { + email, + avatar, + displayName, + deviceName, + }, + }); + const { + client_id, + state, + scope, + code_challenge, + code_challenge_method, + keys_jwk, + } = payload.data; + const url = new URL(oauthUri); + url.searchParams.append("client_id", client_id); + url.searchParams.append("scope", scope); + url.searchParams.append("email", email); + url.searchParams.append("uid", uid); + url.searchParams.append("channel_id", this._channelId); + url.searchParams.append("redirect_uri", PAIRING_REDIRECT_URI); + this._emitter.emit("view:SwitchToWebContent", url.href); + curState.suppConnected(sender, { + client_id, + state, + scope, + code_challenge, + code_challenge_method, + keys_jwk, + }); + break; + case "pair:supp:authorize": + stateMachine.assertState( + [PendingConfirmations, PendingRemoteConfirmation], + `Wrong state for ${message}` + ); + curState.remoteConfirmed(); + break; + default: + throw new Error( + `Received unknown Pairing Channel message: ${message}` + ); + } + } catch (e) { + log.error(e); + curState.hasErrored(e); + } + } + + onPrefViewClosed() { + const curState = this._stateMachine.currentState; + // We don't want to stop the pairing process in the later stages. + if ( + curState instanceof SuppConnectionPending || + curState instanceof Aborted || + curState instanceof Errored + ) { + this.finalize(); + } + } + + /** + * Grant an OAuth authorization code for the connecting client. + * + * @param {Object} options + * @param options.client_id + * @param options.state + * @param options.scope + * @param options.access_type + * @param options.code_challenge_method + * @param options.code_challenge + * @param [options.keys_jwe] + * @returns {Promise<Object>} Object containing "code" and "state" properties. + */ + _authorizeOAuthCode(options) { + return this._fxa._withVerifiedAccountState(async state => { + const { sessionToken } = await state.getUserAccountData(["sessionToken"]); + const params = { ...options }; + if (params.keys_jwk) { + const jwk = JSON.parse( + new TextDecoder().decode( + ChromeUtils.base64URLDecode(params.keys_jwk, { padding: "reject" }) + ) + ); + params.keys_jwe = await this._createKeysJWE( + sessionToken, + params.client_id, + params.scope, + jwk + ); + delete params.keys_jwk; + } + try { + return await this._fxai.fxAccountsClient.oauthAuthorize( + sessionToken, + params + ); + } catch (err) { + throw this._fxai._errorToErrorClass(err); + } + }); + } + + /** + * Create a JWE to deliver keys to another client via the OAuth scoped-keys flow. + * + * This method is used to transfer key material to another client, by providing + * an appropriately-encrypted value for the `keys_jwe` OAuth response parameter. + * Since we're transferring keys from one client to another, two things must be + * true: + * + * * This client must actually have the key. + * * The other client must be allowed to request that key. + * + * @param {String} sessionToken the sessionToken to use when fetching key metadata + * @param {String} clientId the client requesting access to our keys + * @param {String} scopes Space separated requested scopes being requested + * @param {Object} jwk Ephemeral JWK provided by the client for secure key transfer + */ + async _createKeysJWE(sessionToken, clientId, scopes, jwk) { + // This checks with the FxA server about what scopes the client is allowed. + // Note that we pass the requesting client_id here, not our own client_id. + const clientKeyData = await this._fxai.fxAccountsClient.getScopedKeyData( + sessionToken, + clientId, + scopes + ); + const scopedKeys = {}; + for (const scope of Object.keys(clientKeyData)) { + const key = await this._fxai.keys.getKeyForScope(scope); + if (!key) { + throw new Error(`Key not available for scope "${scope}"`); + } + scopedKeys[scope] = key; + } + return lazy.jwcrypto.generateJWE( + jwk, + new TextEncoder().encode(JSON.stringify(scopedKeys)) + ); + } +} |