auth-backend: initial identity provider implementation

plugins/auth-backend/migrations/20200619125845_init.js

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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.
+ */
+
+// @ts-check
+
+/**
+ * @param {import('knex')} knex
+ */
+exports.up = async function up(knex) {
+  return knex.schema.createTable('signing_keys', table => {
+    table.comment(
+      'Signing keys that are currently in use or have recently been used to issue tokens',
+    );
+    table
+      .string('kid')
+      .primary()
+      .notNullable()
+      .comment('ID of the signing key');
+    table
+      .timestamp('created_at')
+      .notNullable()
+      .defaultTo(knex.fn.now())
+      .comment('The creation time of the key');
+    table
+      .string('key')
+      .notNullable()
+      .comment('The serialized public part of the signing key');
+  });
+};
+
+/**
+ * @param {import('knex')} knex
+ */
+exports.down = async function down(knex) {
+  return knex.schema.dropTable('auth_keystore');
+};

plugins/auth-backend/package.json

@@ -32,7 +32,9 @@
     "express-promise-router": "^3.0.3",
     "fs-extra": "^9.0.0",
     "helmet": "^3.22.0",
+    "jose": "^1.27.1",
     "jwt-decode": "2.2.0",
+    "knex": "^0.21.1",
     "morgan": "^1.10.0",
     "passport": "^0.4.1",
     "passport-github2": "^0.1.12",
@@ -46,10 +48,10 @@
     "@types/body-parser": "^1.19.0",
     "@types/cookie-parser": "^1.4.2",
     "@types/jwt-decode": "2.2.1",
+    "@types/passport": "^1.0.3",
     "@types/passport-github2": "^1.2.4",
     "@types/passport-google-oauth20": "^2.0.3",
     "@types/passport-saml": "^1.1.2",
-    "@types/passport": "^1.0.3",
     "jest-fetch-mock": "^3.0.3"
   },
   "files": [

plugins/auth-backend/src/identity/DatabaseKeyStore.ts

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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 Knex from 'knex';
+import path from 'path';
+import { Logger } from 'winston';
+import { PublicKey } from './types';
+
+const migrationsDir = path.resolve(
+  require.resolve('@backstage/plugin-auth-backend/package.json'),
+  '../migrations',
+);
+
+const TABLE = 'signing_keys';
+
+type Row = {
+  created_at: Date;
+  kid: string;
+  key: string;
+};
+
+type Options = {
+  logger: Logger;
+  database: Knex;
+};
+
+export class DatabaseKeyStore {
+  static async create(options: Options): Promise<DatabaseKeyStore> {
+    const { logger, database } = options;
+
+    await database.migrate.latest({
+      directory: migrationsDir,
+    });
+
+    return new DatabaseKeyStore({ logger, database });
+  }
+
+  private readonly logger: Logger;
+  private readonly database: Knex;
+
+  private constructor(options: Options) {
+    const { logger, database } = options;
+
+    this.database = database;
+    this.logger = logger.child({ service: 'key-store' });
+  }
+
+  async addPublicKey(key: PublicKey): Promise<void> {
+    this.logger.info(`Storing public key ${key.kid}`);
+
+    await this.database<Row>(TABLE).insert({
+      kid: key.kid,
+      key: JSON.stringify(key),
+    });
+    console.log(`DEBUG: stored key`);
+  }
+
+  async listPublicKeys(): Promise<PublicKey[]> {
+    const rows = await this.database<Row>(TABLE).select();
+    console.log('DEBUG: rows =', rows);
+    return rows.map(row => JSON.parse(row.key));
+  }
+}

plugins/auth-backend/src/identity/TokenFactory.ts

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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 { TokenIssuer, TokenParams, KeyStore, PublicKey } from './types';
+import { JSONWebKey, JWK, JWS } from 'jose';
+import { Logger } from 'winston';
+
+type Options = {
+  issuer: string;
+  logger: Logger;
+  keyStore: KeyStore;
+};
+
+export class TokenFactory implements TokenIssuer {
+  private readonly issuer: string;
+  private readonly logger: Logger;
+  private readonly keyStore: KeyStore;
+
+  private privateKey?: Promise<JSONWebKey>;
+
+  constructor(options: Options) {
+    const { issuer, logger, keyStore } = options;
+    this.issuer = issuer;
+    this.keyStore = keyStore;
+    this.logger = logger.child({ service: 'issuer' });
+  }
+
+  async issueToken(claims: TokenParams): Promise<string> {
+    const key = await this.getKey();
+
+    const iss = this.issuer;
+    const sub = claims.sub;
+    const aud = 'backstage';
+    const iat = (Date.now() / 1000) | 0;
+    const exp = iat + 3600;
+
+    this.logger.info(`Issuing token for ${sub}`);
+
+    return JWS.sign({ iss, sub, aud, iat, exp }, key, {
+      alg: key.alg,
+      kid: key.kid,
+    });
+  }
+
+  private async getKey(): Promise<JSONWebKey> {
+    if (this.privateKey) {
+      return this.privateKey;
+    }
+
+    this.privateKey = (async () => {
+      const dateStr = new Date().toISOString();
+      const randStr = Math.random().toString(36).slice(2, 6);
+      const kid = `key-${dateStr}-${randStr}`;
+
+      const key = await JWK.generate('EC', 'P-384', { use: 'sig', kid });
+
+      await this.keyStore.addPublicKey(
+        (key.toJWK(false) as unknown) as PublicKey,
+      );
+
+      return key as JSONWebKey;
+    })();
+
+    try {
+      await this.privateKey;
+    } catch (error) {
+      this.logger.error(`Failed to generate signing key, ${error}`);
+    }
+
+    return this.privateKey;
+  }
+}

plugins/auth-backend/src/identity/index.ts

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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.
+ */
+
+export { createOidcRouter } from './router';
+export { TokenFactory } from './TokenFactory';
+export { DatabaseKeyStore } from './DatabaseKeyStore';
+export type { KeyStore, TokenIssuer, TokenParams } from './types';

plugins/auth-backend/src/identity/router.ts

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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 Router from 'express-promise-router';
+import { Logger } from 'winston';
+import { KeyStore } from './types';
+
+export type Options = {
+  logger: Logger;
+  baseUrl: string;
+  keyStore: KeyStore;
+};
+
+export function createOidcRouter(options: Options) {
+  const {
+    logger: baseLogger,
+    keyStore,
+    baseUrl = 'http://localhost:7000/auth',
+  } = options;
+  const logger = baseLogger.child({ router: 'identity' });
+
+  const router = Router();
+
+  const config = {
+    issuer: baseUrl,
+    token_endpoint: `${baseUrl}/v1/token`,
+    userinfo_endpoint: `${baseUrl}/v1/userinfo`,
+    jwks_uri: `${baseUrl}/v1/certs`,
+    response_types_supported: ['id_token'],
+    subject_types_supported: ['public'],
+    id_token_signing_alg_values_supported: ['RS256'],
+    scopes_supported: ['openid'],
+    token_endpoint_auth_methods_supported: [],
+    claims_supported: ['sub'],
+    grant_types_supported: [],
+  };
+
+  router.get('/.well-known/openid-configuration', (_req, res) => {
+    logger.info('request configuration');
+    res.json(config);
+  });
+
+  router.get('/v1/token', (_req, res) => {
+    logger.info('request token');
+    res.status(501).send('Not Implemented');
+  });
+
+  router.get('/v1/userinfo', (_req, res) => {
+    logger.info('request userinfo');
+    res.status(501).send('Not Implemented');
+  });
+
+  router.get('/v1/certs', async (_req, res) => {
+    logger.info('request certs');
+    const keys = await keyStore.listPublicKeys();
+    res.json(keys);
+  });
+
+  return router;
+}

plugins/auth-backend/src/identity/types.ts

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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.
+ */
+
+export interface PublicKey extends Record<string, string> {
+  use: 'sig' | 'enc';
+  alg: string;
+  kid: string;
+  kty: string;
+}
+
+export type KeyStore = {
+  addPublicKey(key: PublicKey): Promise<void>;
+
+  listPublicKeys(): Promise<PublicKey[]>;
+};
+
+export type TokenParams = {
+  sub: string;
+};
+
+export type TokenIssuer = {
+  issueToken(claims: TokenParams): Promise<string>;
+};