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authorized fetch #217

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the implementation is copied from the other places we already check
HTTP signatures, and cross-checked with Firefish's implementation
This commit is contained in:
dakkar 2023-12-20 12:17:59 +00:00
parent 6526968f2d
commit e5ea882ed7
4 changed files with 136 additions and 0 deletions
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2
.config/example.yml
View file

@ -212,6 +212,8 @@ proxyRemoteFiles: true
# Sign to ActivityPub GET request (default: true)
signToActivityPubGet: true
# check that inbound ActivityPub GET requests are signed ("authorized fetch")
checkActivityPubGetSignature: false
# For security reasons, uploading attachments from the intranet is prohibited,
# but exceptions can be made from the following settings. Default value is "undefined".

2
chart/files/default.yml
View file

@ -194,6 +194,8 @@ id: "aidx"
# Sign to ActivityPub GET request (default: true)
signToActivityPubGet: true
# check that inbound ActivityPub GET requests are signed ("authorized fetch")
checkActivityPubGetSignature: false
#allowedPrivateNetworks: [
# '127.0.0.1/32'

3
packages/backend/src/config.ts
View file

@ -88,6 +88,7 @@ type Source = {
customMOTD?: string[];
signToActivityPubGet?: boolean;
checkActivityPubGetSignature?: boolean;
perChannelMaxNoteCacheCount?: number;
perUserNotificationsMaxCount?: number;
@ -146,6 +147,7 @@ export type Config = {
proxyRemoteFiles: boolean | undefined;
customMOTD: string[] | undefined;
signToActivityPubGet: boolean | undefined;
checkActivityPubGetSignature: boolean | undefined;
version: string;
host: string;
@ -253,6 +255,7 @@ export function loadConfig(): Config {
proxyRemoteFiles: config.proxyRemoteFiles,
customMOTD: config.customMOTD,
signToActivityPubGet: config.signToActivityPubGet,
checkActivityPubGetSignature: config.checkActivityPubGetSignature,
mediaProxy: externalMediaProxy ?? internalMediaProxy,
externalMediaProxyEnabled: externalMediaProxy !== null && externalMediaProxy !== internalMediaProxy,
videoThumbnailGenerator: config.videoThumbnailGenerator ?

129
packages/backend/src/server/ActivityPubServerService.ts
View file

@ -5,6 +5,7 @@
import * as crypto from 'node:crypto';
import { IncomingMessage } from 'node:http';
import { format as formatURL } from 'node:url';
import { Inject, Injectable } from '@nestjs/common';
import fastifyAccepts from '@fastify/accepts';
import httpSignature from '@peertube/http-signature';
@ -17,9 +18,13 @@ import type { FollowingsRepository, NotesRepository, EmojisRepository, NoteReact
import * as url from '@/misc/prelude/url.js';
import type { Config } from '@/config.js';
import { ApRendererService } from '@/core/activitypub/ApRendererService.js';
import { ApDbResolverService } from '@/core/activitypub/ApDbResolverService.js';
import { QueueService } from '@/core/QueueService.js';
import type { MiLocalUser, MiRemoteUser, MiUser } from '@/models/User.js';
import { MetaService } from '@/core/MetaService.js';
import { UserKeypairService } from '@/core/UserKeypairService.js';
import { InstanceActorService } from '@/core/InstanceActorService.js';
import type { MiUserPublickey } from '@/models/UserPublickey.js';
import type { MiFollowing } from '@/models/Following.js';
import { countIf } from '@/misc/prelude/array.js';
import type { MiNote } from '@/models/Note.js';
@ -65,9 +70,12 @@ export class ActivityPubServerService {
@Inject(DI.followRequestsRepository)
private followRequestsRepository: FollowRequestsRepository,
private metaService: MetaService,
private utilityService: UtilityService,
private userEntityService: UserEntityService,
private instanceActorService: InstanceActorService,
private apRendererService: ApRendererService,
private apDbResolverService: ApDbResolverService,
private queueService: QueueService,
private userKeypairService: UserKeypairService,
private queryService: QueryService,
@ -99,6 +107,101 @@ export class ActivityPubServerService {
return this.apRendererService.renderCreate(await this.apRendererService.renderNote(note, false), note);
}
@bindThis
private async shouldRefuseGetRequest(request: FastifyRequest, reply: FastifyReply, userId: string | undefined = undefined): Promise<boolean> {
if (!this.config.checkActivityPubGetSignature) return false;
/* this code is inspired from the `inbox` function below, and
`queue/processors/InboxProcessorService`
those pieces of code also check `digest`, and various bits from the
request body, but that only makes sense for requests with a body:
here we're validating GET requests
this is also inspired by FireFish's `checkFetch`
*/
/* we always allow requests about our instance actor, because when
a remote instance needs to check our signature on a request we
sent, it will need to fetch information about the user that
signed it (which is our instance actor), and if we try to check
their signature on *that* request, we'll fetch *their* instance
actor... leading to an infinite recursion */
if (userId) {
const instanceActor = await this.instanceActorService.getInstanceActor();
if (userId === instanceActor.id) return false;
}
let signature;
try {
signature = httpSignature.parseRequest(request.raw, { 'headers': [] });
} catch (e) {
// not signed, or malformed signature: refuse
reply.code(401);
return true;
}
if (signature.params.headers.indexOf('host') === -1
|| request.headers.host !== this.config.host) {
// no destination host, or not us: refuse
reply.code(401);
return true;
}
const keyId = new URL(signature.keyId);
const keyHost = this.utilityService.toPuny(keyId.hostname);
const meta = await this.metaService.fetch();
if (this.utilityService.isBlockedHost(meta.blockedHosts, keyHost)) {
/* blocked instance: refuse (we don't care if the signature is
good, if they even pretend to be from a blocked instance,
they're out) */
reply.code(401);
return true;
}
// do we know the signer already?
let authUser: {
user: MiRemoteUser;
key: MiUserPublickey | null;
} | null = await this.apDbResolverService.getAuthUserFromKeyId(signature.keyId);
if (authUser == null) {
/* keyId is often in the shape `${user.uri}#${keyname}`, try
fetching information about the remote user */
const candidate = formatURL(keyId, { fragment: false });
authUser = await this.apDbResolverService.getAuthUserFromApId(candidate);
}
if (authUser?.key == null) {
// we can't figure out who the signer is, or we can't get their key: refuse
reply.code(401);
return true;
}
let httpSignatureValidated = httpSignature.verifySignature(signature, authUser.key.keyPem);
if (!httpSignatureValidated) {
// maybe they changed their key? refetch it
authUser.key = await this.apDbResolverService.refetchPublicKeyForApId(authUser.user);
if (authUser.key != null) {
httpSignatureValidated = httpSignature.verifySignature(signature, authUser.key.keyPem);
}
}
if (!httpSignatureValidated) {
// bad signature: refuse
reply.code(401);
return true;
}
// all good, don't refuse
return false;
}
@bindThis
private inbox(request: FastifyRequest, reply: FastifyReply) {
let signature;
@ -172,6 +275,8 @@ export class ActivityPubServerService {
request: FastifyRequest<{ Params: { user: string; }; Querystring: { cursor?: string; page?: string; }; }>,
reply: FastifyReply,
) {
if (await this.shouldRefuseGetRequest(request, reply, request.params.user)) return;
const userId = request.params.user;
const cursor = request.query.cursor;
@ -264,6 +369,8 @@ export class ActivityPubServerService {
request: FastifyRequest<{ Params: { user: string; }; Querystring: { cursor?: string; page?: string; }; }>,
reply: FastifyReply,
) {
if (await this.shouldRefuseGetRequest(request, reply, request.params.user)) return;
const userId = request.params.user;
const cursor = request.query.cursor;
@ -353,6 +460,8 @@ export class ActivityPubServerService {
@bindThis
private async featured(request: FastifyRequest<{ Params: { user: string; }; }>, reply: FastifyReply) {
if (await this.shouldRefuseGetRequest(request, reply, request.params.user)) return;
const userId = request.params.user;
const user = await this.usersRepository.findOneBy({
@ -397,6 +506,8 @@ export class ActivityPubServerService {
}>,
reply: FastifyReply,
) {
if (await this.shouldRefuseGetRequest(request, reply, request.params.user)) return;
const userId = request.params.user;
const sinceId = request.query.since_id;
@ -551,6 +662,8 @@ export class ActivityPubServerService {
// note
fastify.get<{ Params: { note: string; } }>('/notes/:note', { constraints: { apOrHtml: 'ap' } }, async (request, reply) => {
if (await this.shouldRefuseGetRequest(request, reply)) return;
vary(reply.raw, 'Accept');
const note = await this.notesRepository.findOneBy({
@ -581,6 +694,8 @@ export class ActivityPubServerService {
// note activity
fastify.get<{ Params: { note: string; } }>('/notes/:note/activity', async (request, reply) => {
if (await this.shouldRefuseGetRequest(request, reply)) return;
vary(reply.raw, 'Accept');
const note = await this.notesRepository.findOneBy({
@ -623,6 +738,8 @@ export class ActivityPubServerService {
// publickey
fastify.get<{ Params: { user: string; } }>('/users/:user/publickey', async (request, reply) => {
if (await this.shouldRefuseGetRequest(request, reply, request.params.user)) return;
const userId = request.params.user;
const user = await this.usersRepository.findOneBy({
@ -648,6 +765,8 @@ export class ActivityPubServerService {
});
fastify.get<{ Params: { user: string; } }>('/users/:user', { constraints: { apOrHtml: 'ap' } }, async (request, reply) => {
if (await this.shouldRefuseGetRequest(request, reply, request.params.user)) return;
const userId = request.params.user;
const user = await this.usersRepository.findOneBy({
@ -660,6 +779,8 @@ export class ActivityPubServerService {
});
fastify.get<{ Params: { user: string; } }>('/@:user', { constraints: { apOrHtml: 'ap' } }, async (request, reply) => {
if (await this.shouldRefuseGetRequest(request, reply, request.params.user)) return;
const user = await this.usersRepository.findOneBy({
usernameLower: request.params.user.toLowerCase(),
host: IsNull(),
@ -672,6 +793,8 @@ export class ActivityPubServerService {
// emoji
fastify.get<{ Params: { emoji: string; } }>('/emojis/:emoji', async (request, reply) => {
if (await this.shouldRefuseGetRequest(request, reply)) return;
const emoji = await this.emojisRepository.findOneBy({
host: IsNull(),
name: request.params.emoji,
@ -689,6 +812,8 @@ export class ActivityPubServerService {
// like
fastify.get<{ Params: { like: string; } }>('/likes/:like', async (request, reply) => {
if (await this.shouldRefuseGetRequest(request, reply)) return;
const reaction = await this.noteReactionsRepository.findOneBy({ id: request.params.like });
if (reaction == null) {
@ -710,6 +835,8 @@ export class ActivityPubServerService {
// follow
fastify.get<{ Params: { follower: string; followee: string; } }>('/follows/:follower/:followee', async (request, reply) => {
if (await this.shouldRefuseGetRequest(request, reply)) return;
// This may be used before the follow is completed, so we do not
// check if the following exists.
@ -736,6 +863,8 @@ export class ActivityPubServerService {
// follow
fastify.get<{ Params: { followRequestId: string ; } }>('/follows/:followRequestId', async (request, reply) => {
if (await this.shouldRefuseGetRequest(request, reply)) return;
// This may be used before the follow is completed, so we do not
// check if the following exists and only check if the follow request exists.