implement mastodon oauth authorization

packages/backend/migration/1736599563231-MastodonApp.js

@@ -0,0 +1,18 @@
+export class MastodonOauth1736599563231 {
+    name = 'MastodonOauth1736599563231'
+
+    async up(queryRunner) {
+        await queryRunner.query(`ALTER TABLE "app" ADD "website" character varying(128)`);
+        await queryRunner.query(`COMMENT ON COLUMN "app"."website" IS 'Application website.'`);
+        await queryRunner.query(`ALTER TABLE "app" ADD "mastodonScopes" character varying(64) array`);
+        await queryRunner.query(`COMMENT ON COLUMN "app"."mastodonScopes" IS 'Mastodon app scopes, only set for apps created with Mastodon API.'`);
+        await queryRunner.query(`ALTER TABLE "app" ADD "redirectUris" character varying(512) array DEFAULT '{}' NOT NULL`);
+        await queryRunner.query(`COMMENT ON COLUMN "app"."redirectUris" IS 'Redirect URIs.'`);
+    }
+
+    async down(queryRunner) {
+        await queryRunner.query(`ALTER TABLE "app" DROP COLUMN "website"`);
+        await queryRunner.query(`ALTER TABLE "app" DROP COLUMN "mastodonScopes"`);
+        await queryRunner.query(`ALTER TABLE "app" DROP COLUMN "redirectUris"`);
+    }
+}

packages/backend/src/misc/mastodon/mastodon-to-misskey-scopes.ts

@@ -0,0 +1,41 @@
+import { permissions } from 'misskey-js';
+
+const mastodonToMisskeyScopes: Map<string, (typeof permissions)[number][]> = new Map([
+	['profile', ['read:account']],
+	['follow', ['read:following', 'write:following', 'read:blocks', 'write:blocks', 'read:mutes', 'write:mutes']],
+	['read:accounts', ['read:account']],
+	['read:blocks', ['read:blocks']],
+	['read:bookmarks', ['read:favorites']],
+	['read:favourites', ['read:reactions']],
+	['read:filters', ['read:account']],
+	['read:follows', ['read:following']],
+	['read:lists', ['read:account']],
+	['read:mutes', ['read:mutes']],
+	['read:notifications', ['read:notifications']],
+	['read:search', []],
+	['read:statuses', []],
+	['write:accounts', ['write:account']],
+	['write:blocks', ['write:blocks']],
+	['write:bookmarks', ['write:favorites']],
+	['write:conversations', ['write:notes']],
+	['write:favourites', ['write:reactions']],
+	['write:filters', ['write:account']],
+	['write:follows', ['write:following']],
+	['write:lists', ['write:account']],
+	['write:media', ['read:drive', 'write:drive']],
+	['write:mutes', ['write:mutes']],
+	['write:notifications', ['write:notifications']],
+	['write:reports', ['write:report-abuse']],
+	['write:statuses', ['write:notes']],
+]);
+
+function setHighLevelScope(scopeName: string) {
+	const granularScopes = Array.from(mastodonToMisskeyScopes)
+		.flatMap(([key, value]) => key.startsWith(scopeName + ':') ? value : []);
+	mastodonToMisskeyScopes.set(scopeName, Array.from(new Set(granularScopes)));
+}
+
+setHighLevelScope('read');
+setHighLevelScope('write');
+
+export { mastodonToMisskeyScopes };

packages/backend/src/models/App.ts

@@ -63,4 +63,22 @@ export class MiApp {
 		comment: 'The callbackUrl of the App.',
 	})
 	public callbackUrl: string | null;
+
+	@Column('varchar', {
+		length: 128, nullable: true,
+		comment: 'Application website.',
+	})
+	public website: string;
+
+	@Column('varchar', {
+		length: 64, array: true, nullable: true,
+		comment: 'Mastodon app scopes, only set for apps created with Mastodon API.',
+	})
+	public mastodonScopes: string[];
+
+	@Column('varchar', {
+		length: 512, array: true, nullable: true,
+		comment: 'Redirect URIs.',
+	})
+	public redirectUris: string[];
 }

packages/backend/src/server/api/MastodonEndpointsModule.ts

@@ -2,8 +2,10 @@ import { Module, Provider } from '@nestjs/common';
 
 import { CoreModule } from '@/core/CoreModule.js';
 import * as mep___accounts_lookup_v1_get from './mastodon/accounts/lookup/v1/get.js';
+import * as mep___apps_v1_post from './mastodon/apps/v1/post.js';
 
 const $accounts_lookup_v1_get: Provider = { provide: 'mep:GET:v1/accounts/lookup', useClass: mep___accounts_lookup_v1_get.default };
+const $apps_v1_post: Provider = { provide: 'mep:POST:v1/apps', useClass: mep___apps_v1_post.default };
 
 @Module({
 	imports: [
@@ -11,9 +13,11 @@ const $accounts_lookup_v1_get: Provider = { provide: 'mep:GET:v1/accounts/lookup
 	],
 	providers: [
 		$accounts_lookup_v1_get,
+		$apps_v1_post,
 	],
 	exports: [
 		$accounts_lookup_v1_get,
+		$apps_v1_post,
 	],
 })
 export class MastodonEndpointsModule {}

packages/backend/src/server/api/mastodon-endpoints.ts

@@ -1,8 +1,10 @@
 import { Schema } from '@/misc/json-schema.js';
 import * as mep___accounts_lookup_v1_get from './mastodon/accounts/lookup/v1/get.js';
+import * as mep___apps_v1_post from './mastodon/apps/v1/post.js';
 
 const eps = [
 	['GET', 'v1/accounts/lookup', mep___accounts_lookup_v1_get],
+	['POST', 'v1/apps', mep___apps_v1_post],
 ];
 
 export interface IMastodonEndpointMeta {

packages/backend/src/server/api/mastodon/apps/v1/post.ts

@@ -0,0 +1,80 @@
+import { Inject, Injectable } from '@nestjs/common';
+import { MastodonEndpoint } from '@/server/api/mastodon-endpoint-base.js';
+import { MastodonApiError } from '@/server/api/error.js';
+import { secureRndstr } from '@/misc/secure-rndstr.js';
+import type { AppsRepository } from '@/models/_.js';
+import { DI } from '@/di-symbols.js';
+import { IdService } from '@/core/IdService.js';
+import { mastodonToMisskeyScopes } from '@/misc/mastodon/mastodon-to-misskey-scopes.js';
+
+export const meta = {
+	requireCredential: false,
+} as const;
+
+export const paramDef = {
+	type: 'object',
+	properties: {
+		client_name: { type: 'string', minLength: 1 },
+		redirect_uri: { type: 'string', minLength: 1 },
+		redirect_uris: {
+			anyOf: [
+				{ type: 'array', minItems: 1, items: { type: 'string', minLength: 1 } },
+				{ type: 'string', minLength: 1 },
+			],
+		},
+		scopes: { type: 'string', minLength: 1 },
+		website: { type: 'string' },
+	},
+	anyOf: [
+		{ required: ['redirect_uri'] },
+		{ required: ['redirect_uris'] },
+	],
+	required: ['client_name'],
+} as const;
+
+@Injectable()
+export default class extends MastodonEndpoint<typeof meta, typeof paramDef> { // eslint-disable-line import/no-default-export
+	constructor(
+		@Inject(DI.appsRepository)
+		private appsRepository: AppsRepository,
+
+		private idService: IdService,
+	) {
+		super(meta, paramDef, async (ps, me) => {
+			const redirectUrlsRawValue = ps.redirect_uris ?? ps.redirect_uri ?? [];
+			const redirectUris = typeof redirectUrlsRawValue === 'string' ? redirectUrlsRawValue.split('\n') : redirectUrlsRawValue;
+			const secret = secureRndstr(32);
+			const mastodonScopes = (ps.scopes ?? 'read').split(' ');
+			const scopes = mastodonScopes.flatMap(scope => {
+				const misskeyScopes = mastodonToMisskeyScopes.get(scope);
+				if (!misskeyScopes) {
+					throw new MastodonApiError('Scopes doesn\'t match configured on the server.', 400);
+				}
+				return misskeyScopes;
+			});
+			const clientId = this.idService.gen();
+			await this.appsRepository.insert({
+				id: clientId,
+				userId: me ? me.id : null,
+				name: ps.client_name,
+				description: ps.website,
+				permission: scopes,
+				callbackUrl: null,
+				secret: secret,
+				website: ps.website,
+				mastodonScopes: mastodonScopes,
+				redirectUris: redirectUris,
+			});
+			return {
+				id: clientId,
+				name: ps.client_name,
+				website: ps.website,
+				scopes: mastodonScopes,
+				redirect_uri: redirectUris.join('\n'),
+				redirect_uris: redirectUris,
+				client_id: `mastodon:${clientId}`,
+				client_secret: secret,
+			};
+		});
+	}
+}

packages/backend/src/server/oauth/OAuth2ProviderService.ts

@@ -34,6 +34,7 @@ import { DI } from '@/di-symbols.js';
 import { bindThis } from '@/decorators.js';
 import type {
 	AccessTokensRepository,
+	AppsRepository,
 	IndieAuthClientsRepository,
 	UserProfilesRepository,
 	UsersRepository,
@@ -45,9 +46,15 @@ import { LoggerService } from '@/core/LoggerService.js';
 import Logger from '@/logger.js';
 import { StatusError } from '@/misc/status-error.js';
 import { normalizeEmailAddress } from '@/misc/normalize-email-address.js';
+import { mastodonToMisskeyScopes } from '@/misc/mastodon/mastodon-to-misskey-scopes.js';
 import type { ServerResponse } from 'node:http';
 import type { FastifyInstance } from 'fastify';
 
+function extractMastodonAppId(clientId: string): string | null {
+	const MASTODON_CLIENT_ID_PREFIX = 'mastodon:';
+	return clientId.startsWith(MASTODON_CLIENT_ID_PREFIX) ? clientId.substring(MASTODON_CLIENT_ID_PREFIX.length) : null;
+}
+
 // TODO: Consider migrating to @node-oauth/oauth2-server once
 // https://github.com/node-oauth/node-oauth2-server/issues/180 is figured out.
 // Upstream the various validations and RFC9207 implementation in that case.
@@ -258,6 +265,8 @@ export class OAuth2ProviderService {
 		private usersRepository: UsersRepository,
 		@Inject(DI.userProfilesRepository)
 		private userProfilesRepository: UserProfilesRepository,
+		@Inject(DI.appsRepository)
+		private appsRepository: AppsRepository,
 
 		private idService: IdService,
 		private cacheService: CacheService,
@@ -328,13 +337,25 @@ export class OAuth2ProviderService {
 				if (body.client_id !== granted.clientId) return;
 				if (redirectUri !== granted.redirectUri) return;
 
+				const mastodonAppId = extractMastodonAppId(granted.clientId);
+
 				// https://datatracker.ietf.org/doc/html/rfc7636.html#section-4.6
+				// For Mastodon API, code verifier isn't necessary (but if code challenge was provided, then it should be verified)
+				if (!mastodonAppId || granted.codeChallenge || body.code_verifier) {
 					if (!body.code_verifier) return;
 					if (!(await verifyChallenge(body.code_verifier as string, granted.codeChallenge))) return;
+				}
 
 				const accessToken = secureRndstr(128);
 				const now = new Date();
 
+				let scopes = granted.scopes;
+				let name = granted.clientId;
+				if (mastodonAppId) {
+					scopes = [...new Set(granted.scopes.flatMap((scope: string) => mastodonToMisskeyScopes.get(scope)))];
+					name = (await this.appsRepository.findOneBy({ id: mastodonAppId }))?.name ?? name;
+				}
+
 				// NOTE: we don't have a setup for automatic token expiration
 				await accessTokensRepository.insert({
 					id: idService.gen(now.getTime()),
@@ -342,8 +363,9 @@ export class OAuth2ProviderService {
 					userId: granted.userId,
 					token: accessToken,
 					hash: accessToken,
-					name: granted.clientId,
+					name: name,
-					permission: granted.scopes,
+					permission: scopes,
+					appId: mastodonAppId,
 				});
 
 				grantedState = await this.redisClient.get(`oauth2:authorization:${code}:state`);
@@ -354,7 +376,7 @@ export class OAuth2ProviderService {
 				}
 
 				granted.grantedToken = accessToken;
-				this.#logger.info(`Generated access token for ${granted.clientId} for user ${granted.userId}, with scope: [${granted.scopes}]`);
+				this.#logger.info(`Generated access token for ${granted.clientId} for user ${granted.userId}, with scope: [${scopes}]`);
 				await this.redisClient.set(`oauth2:authorization:${code}`, JSON.stringify(granted), 'EX', 60 * 5);
 
 				return [accessToken, undefined, { scope: granted.scopes.join(' ') }];
@@ -418,6 +440,31 @@ export class OAuth2ProviderService {
 
 				this.#logger.info(`Validating authorization parameters, with client_id: ${clientID}, redirect_uri: ${redirectURI}, scope: ${scope}`);
 
+				let clientInfo: ClientInformation;
+				const mastodonAppId = extractMastodonAppId(clientID);
+				if (mastodonAppId) {
+					const app = await this.appsRepository.findOneBy({ id: mastodonAppId });
+					if (!app) {
+						throw new AuthorizationError('unrecognized client id', 'invalid_request');
+					}
+					clientInfo = {
+						id: clientID,
+						name: app.name,
+						redirectUris: app.redirectUris,
+					};
+					if (codeChallengeMethod && codeChallengeMethod !== 'S256') {
+						throw new AuthorizationError('`code_challenge_method` parameter must be set as S256', 'invalid_request');
+					}
+					try {
+						const scopes = [...new Set(scope)].filter(s => mastodonToMisskeyScopes.has(s));
+						if (!scopes.length) {
+							throw new AuthorizationError('`scope` parameter has no known scope', 'invalid_scope');
+						}
+						areq.scope = scopes;
+					} catch (err) {
+						return [err as Error, clientInfo, redirectURI];
+					}
+				} else {
 					const clientUrl = validateClientId(clientID);
 
 					// https://indieauth.spec.indieweb.org/#client-information-discovery
@@ -434,13 +481,7 @@ export class OAuth2ProviderService {
 					// Find client information from the database.
 					const registeredClientInfo = await this.indieAuthClientsRepository.findOneBy({ id: clientUrl.href }) as ClientInformation | null;
 					// Find client information from the remote.
-				const clientInfo = registeredClientInfo ?? await discoverClientInformation(this.#logger, this.httpRequestService, clientUrl.href);
+					clientInfo = registeredClientInfo ?? await discoverClientInformation(this.#logger, this.httpRequestService, clientUrl.href);
-
-				// Require the redirect URI to be included in an explicit list, per
-				// https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics#section-4.1.3
-				if (!clientInfo.redirectUris.includes(redirectURI)) {
-					throw new AuthorizationError('Invalid redirect_uri', 'invalid_request');
-				}
 
 					try {
 						const scopes = [...new Set(scope)].filter(s => (<readonly string[]>kinds).includes(s));
@@ -449,7 +490,7 @@ export class OAuth2ProviderService {
 						}
 						areq.scope = scopes;
 
-					// Require PKCE parameters.
+						// Require PKCE parameters. This requirement is skipped for Mastodon clients, as Mastodon API doesn't require it.
 						// Recommended by https://indieauth.spec.indieweb.org/#authorization-request, but also prevents downgrade attack:
 						// https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics#name-pkce-downgrade-attack
 						if (typeof codeChallenge !== 'string') {
@@ -461,6 +502,12 @@ export class OAuth2ProviderService {
 					} catch (err) {
 						return [err as Error, clientInfo, redirectURI];
 					}
+				}
+				// Require the redirect URI to be included in an explicit list, per
+				// https://datatracker.ietf.org/doc/html/draft-ietf-oauth-security-topics#section-4.1.3
+				if (!clientInfo.redirectUris.includes(redirectURI)) {
+					throw new AuthorizationError('Invalid redirect_uri', 'invalid_request');
+				}
 
 				return [null, clientInfo, redirectURI];
 			})().then(args => done(...args), err => done(err));