merge: some validation fixes (!484)

View MR for information: https://activitypub.software/TransFem-org/Sharkey/-/merge_requests/484

Closes #469

Approved-by: Amelia Yukii <amelia.yukii@shourai.de>

packages/backend/src/core/HttpRequestService.ts

@@ -15,6 +15,7 @@ import type { Config } from '@/config.js';
 import { StatusError } from '@/misc/status-error.js';
 import { bindThis } from '@/decorators.js';
 import { validateContentTypeSetAsActivityPub } from '@/core/activitypub/misc/validator.js';
+import { assertActivityMatchesUrls } from '@/core/activitypub/misc/check-against-url.js';
 import type { IObject } from '@/core/activitypub/type.js';
 import type { Response } from 'node-fetch';
 import type { URL } from 'node:url';
@@ -125,7 +126,12 @@ export class HttpRequestService {
 			validators: [validateContentTypeSetAsActivityPub],
 		});
 
-		return await res.json() as IObject;
+		const finalUrl = res.url; // redirects may have been involved
+		const activity = await res.json() as IObject;
+
+		assertActivityMatchesUrls(activity, [url, finalUrl]);
+
+		return activity;
 	}
 
 	@bindThis

packages/backend/src/core/UtilityService.ts

@@ -86,7 +86,7 @@ export class UtilityService {
 	@bindThis
 	public extractDbHost(uri: string): string {
 		const url = new URL(uri);
-		return this.toPuny(url.hostname);
+		return this.toPuny(url.host);
 	}
 
 	@bindThis
@@ -99,4 +99,11 @@ export class UtilityService {
 		if (host == null) return null;
 		return toASCII(host.toLowerCase());
 	}
+
+	@bindThis
+	public punyHost(url: string): string {
+		const urlObj = new URL(url);
+		const host = `${this.toPuny(urlObj.hostname)}${urlObj.port.length > 0 ? ':' + urlObj.port : ''}`;
+		return host;
+	}
 }

packages/backend/src/core/activitypub/ApRequestService.ts

@@ -14,7 +14,9 @@ import { HttpRequestService } from '@/core/HttpRequestService.js';
 import { LoggerService } from '@/core/LoggerService.js';
 import { bindThis } from '@/decorators.js';
 import type Logger from '@/logger.js';
+import type { IObject } from './type.js';
 import { validateContentTypeSetAsActivityPub } from '@/core/activitypub/misc/validator.js';
+import { assertActivityMatchesUrls } from '@/core/activitypub/misc/check-against-url.js';
 
 type Request = {
 	url: string;
@@ -201,6 +203,11 @@ export class ApRequestService {
 			validators: [validateContentTypeSetAsActivityPub],
 		});
 
-		return await res.json();
+		const finalUrl = res.url; // redirects may have been involved
+		const activity = await res.json() as IObject;
+
+		assertActivityMatchesUrls(activity, [url, finalUrl]);
+
+		return activity;
 	}
 }

packages/backend/src/core/activitypub/ApResolverService.ts

@@ -115,6 +115,14 @@ export class Resolver {
 			throw new Error('invalid response');
 		}
 
+		// HttpRequestService / ApRequestService have already checked that
+		// `object.id` or `object.url` matches the URL used to fetch the
+		// object after redirects; here we double-check that no redirects
+		// bounced between hosts
+		if (object.id && (this.utilityService.punyHost(object.id) !== this.utilityService.punyHost(value))) {
+			throw new Error(`invalid AP object ${value}: id ${object.id} has different host`);
+		}
+
 		return object;
 	}
 

packages/backend/src/core/activitypub/misc/check-against-url.ts

@@ -0,0 +1,19 @@
+/*
+ * SPDX-FileCopyrightText: dakkar and sharkey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+import type { IObject } from '../type.js';
+
+export function assertActivityMatchesUrls(activity: IObject, urls: string[]) {
+	const idOk = activity.id !== undefined && urls.includes(activity.id);
+
+	// technically `activity.url` could be an `ApObject = IObject |
+	// string | (IObject | string)[]`, but if it's a complicated thing
+	// and the `activity.id` doesn't match, I think we're fine
+	// rejecting the activity
+	const urlOk = typeof(activity.url) === 'string' && urls.includes(activity.url);
+
+	if (!idOk && !urlOk) {
+		throw new Error(`bad Activity: neither id(${activity?.id}) nor url(${activity?.url}) match location(${urls})`);
+	}
+}

packages/backend/src/core/activitypub/models/ApPersonService.ts

@@ -127,12 +127,6 @@ export class ApPersonService implements OnModuleInit {
 		this.logger = this.apLoggerService.logger;
 	}
 
-	private punyHost(url: string): string {
-		const urlObj = new URL(url);
-		const host = `${this.utilityService.toPuny(urlObj.hostname)}${urlObj.port.length > 0 ? ':' + urlObj.port : ''}`;
-		return host;
-	}
-
 	/**
 	 * Validate and convert to actor object
 	 * @param x Fetched object
@@ -140,7 +134,7 @@ export class ApPersonService implements OnModuleInit {
 	 */
 	@bindThis
 	private validateActor(x: IObject, uri: string): IActor {
-		const expectHost = this.punyHost(uri);
+		const expectHost = this.utilityService.punyHost(uri);
 
 		if (!isActor(x)) {
 			throw new Error(`invalid Actor type '${x.type}'`);
@@ -154,6 +148,19 @@ export class ApPersonService implements OnModuleInit {
 			throw new Error('invalid Actor: wrong inbox');
 		}
 
+		if (this.utilityService.punyHost(x.inbox) !== expectHost) {
+			throw new Error('invalid Actor: inbox has different host');
+		}
+
+		for (const collection of ['outbox', 'followers', 'following'] as (keyof IActor)[]) {
+			const collectionUri = (x as IActor)[collection];
+			if (typeof collectionUri === 'string' && collectionUri.length > 0) {
+				if (this.utilityService.punyHost(collectionUri) !== expectHost) {
+					throw new Error(`invalid Actor: ${collection} has different host`);
+				}
+			}
+		}
+
 		if (!(typeof x.preferredUsername === 'string' && x.preferredUsername.length > 0 && x.preferredUsername.length <= 128 && /^\w([\w-.]*\w)?$/.test(x.preferredUsername))) {
 			throw new Error('invalid Actor: wrong username');
 		}
@@ -177,7 +184,7 @@ export class ApPersonService implements OnModuleInit {
 			x.summary = truncate(x.summary, summaryLength);
 		}
 
-		const idHost = this.punyHost(x.id);
+		const idHost = this.utilityService.punyHost(x.id);
 		if (idHost !== expectHost) {
 			throw new Error('invalid Actor: id has different host');
 		}
@@ -187,7 +194,7 @@ export class ApPersonService implements OnModuleInit {
 				throw new Error('invalid Actor: publicKey.id is not a string');
 			}
 
-			const publicKeyIdHost = this.punyHost(x.publicKey.id);
+			const publicKeyIdHost = this.utilityService.punyHost(x.publicKey.id);
 			if (publicKeyIdHost !== expectHost) {
 				throw new Error('invalid Actor: publicKey.id has different host');
 			}
@@ -286,7 +293,7 @@ export class ApPersonService implements OnModuleInit {
 
 		this.logger.info(`Creating the Person: ${person.id}`);
 
-		const host = this.punyHost(object.id);
+		const host = this.utilityService.punyHost(object.id);
 
 		const fields = this.analyzeAttachments(person.attachment ?? []);
 

packages/backend/src/server/api/endpoints/ap/show.ts

@@ -113,8 +113,9 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 	@bindThis
 	private async fetchAny(uri: string, me: MiLocalUser | null | undefined): Promise<SchemaType<typeof meta['res']> | null> {
 	// ブロックしてたら中断
+		const host = this.utilityService.extractDbHost(uri);
 		const fetchedMeta = await this.metaService.fetch();
-		if (this.utilityService.isBlockedHost(fetchedMeta.blockedHosts, this.utilityService.extractDbHost(uri))) return null;
+		if (this.utilityService.isBlockedHost(fetchedMeta.blockedHosts, host)) return null;
 
 		let local = await this.mergePack(me, ...await Promise.all([
 			this.apDbResolverService.getUserFromApId(uri),
@@ -122,6 +123,9 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		]));
 		if (local != null) return local;
 
+		// local object, not found in db? fail
+		if (this.utilityService.isSelfHost(host)) return null;
+
 		// リモートから一旦オブジェクトフェッチ
 		const resolver = this.apResolverService.createResolver();
 		const object = await resolver.resolve(uri) as any;