From 41f2ebae4f970932fb62d2d8923b1f776f0b1494 Mon Sep 17 00:00:00 2001
From: Chocobozzz <me@florianbigard.com>
Date: Fri, 19 Oct 2018 11:41:19 +0200
Subject: Add HTTP signature check before linked signature

It's faster, and will allow us to use RSA signature 2018 (with upstream
jsonld-signature module) without too much incompatibilities in the
peertube federation
---
 server/middlewares/activitypub.ts                  | 94 +++++++++++++++++-----
 .../validators/activitypub/signature.ts            | 16 +++-
 2 files changed, 88 insertions(+), 22 deletions(-)

(limited to 'server/middlewares')

diff --git a/server/middlewares/activitypub.ts b/server/middlewares/activitypub.ts
index d7f59be8c..1ec888477 100644
--- a/server/middlewares/activitypub.ts
+++ b/server/middlewares/activitypub.ts
@@ -2,34 +2,32 @@ import { eachSeries } from 'async'
 import { NextFunction, Request, RequestHandler, Response } from 'express'
 import { ActivityPubSignature } from '../../shared'
 import { logger } from '../helpers/logger'
-import { isSignatureVerified } from '../helpers/peertube-crypto'
-import { ACCEPT_HEADERS, ACTIVITY_PUB } from '../initializers'
+import { isHTTPSignatureVerified, isJsonLDSignatureVerified, parseHTTPSignature } from '../helpers/peertube-crypto'
+import { ACCEPT_HEADERS, ACTIVITY_PUB, HTTP_SIGNATURE } from '../initializers'
 import { getOrCreateActorAndServerAndModel } from '../lib/activitypub'
 import { ActorModel } from '../models/activitypub/actor'
+import { loadActorUrlOrGetFromWebfinger } from '../helpers/webfinger'
 
 async function checkSignature (req: Request, res: Response, next: NextFunction) {
-  const signatureObject: ActivityPubSignature = req.body.signature
+  try {
+    const httpSignatureChecked = await checkHttpSignature(req, res)
+    if (httpSignatureChecked !== true) return
 
-  const [ creator ] = signatureObject.creator.split('#')
+    const actor: ActorModel = res.locals.signature.actor
 
-  logger.debug('Checking signature of actor %s...', creator)
+    // Forwarded activity
+    const bodyActor = req.body.actor
+    const bodyActorId = bodyActor && bodyActor.id ? bodyActor.id : bodyActor
+    if (bodyActorId && bodyActorId !== actor.url) {
+      const jsonLDSignatureChecked = await checkJsonLDSignature(req, res)
+      if (jsonLDSignatureChecked !== true) return
+    }
 
-  let actor: ActorModel
-  try {
-    actor = await getOrCreateActorAndServerAndModel(creator)
+    return next()
   } catch (err) {
-    logger.warn('Cannot create remote actor %s and check signature.', creator, { err })
+    logger.error('Error in ActivityPub signature checker.', err)
     return res.sendStatus(403)
   }
-
-  const verified = await isSignatureVerified(actor, req.body)
-  if (verified === false) return res.sendStatus(403)
-
-  res.locals.signature = {
-    actor
-  }
-
-  return next()
 }
 
 function executeIfActivityPub (fun: RequestHandler | RequestHandler[]) {
@@ -57,3 +55,63 @@ export {
   checkSignature,
   executeIfActivityPub
 }
+
+// ---------------------------------------------------------------------------
+
+async function checkHttpSignature (req: Request, res: Response) {
+  // FIXME: mastodon does not include the Signature scheme
+  const sig = req.headers[HTTP_SIGNATURE.HEADER_NAME] as string
+  if (sig && sig.startsWith('Signature ') === false) req.headers[HTTP_SIGNATURE.HEADER_NAME] = 'Signature ' + sig
+
+  const parsed = parseHTTPSignature(req)
+
+  const keyId = parsed.keyId
+  if (!keyId) {
+    res.sendStatus(403)
+    return false
+  }
+
+  logger.debug('Checking HTTP signature of actor %s...', keyId)
+
+  let [ actorUrl ] = keyId.split('#')
+  if (actorUrl.startsWith('acct:')) {
+    actorUrl = await loadActorUrlOrGetFromWebfinger(actorUrl.replace(/^acct:/, ''))
+  }
+
+  const actor = await getOrCreateActorAndServerAndModel(actorUrl)
+
+  const verified = isHTTPSignatureVerified(parsed, actor)
+  if (verified !== true) {
+    res.sendStatus(403)
+    return false
+  }
+
+  res.locals.signature = { actor }
+
+  return true
+}
+
+async function checkJsonLDSignature (req: Request, res: Response) {
+  const signatureObject: ActivityPubSignature = req.body.signature
+
+  if (!signatureObject.creator) {
+    res.sendStatus(403)
+    return false
+  }
+
+  const [ creator ] = signatureObject.creator.split('#')
+
+  logger.debug('Checking JsonLD signature of actor %s...', creator)
+
+  const actor = await getOrCreateActorAndServerAndModel(creator)
+  const verified = await isJsonLDSignatureVerified(actor, req.body)
+
+  if (verified !== true) {
+    res.sendStatus(403)
+    return false
+  }
+
+  res.locals.signature = { actor }
+
+  return true
+}
diff --git a/server/middlewares/validators/activitypub/signature.ts b/server/middlewares/validators/activitypub/signature.ts
index 4efe9aafa..be14e92ea 100644
--- a/server/middlewares/validators/activitypub/signature.ts
+++ b/server/middlewares/validators/activitypub/signature.ts
@@ -9,10 +9,18 @@ import { logger } from '../../../helpers/logger'
 import { areValidationErrors } from '../utils'
 
 const signatureValidator = [
-  body('signature.type').custom(isSignatureTypeValid).withMessage('Should have a valid signature type'),
-  body('signature.created').custom(isDateValid).withMessage('Should have a valid signature created date'),
-  body('signature.creator').custom(isSignatureCreatorValid).withMessage('Should have a valid signature creator'),
-  body('signature.signatureValue').custom(isSignatureValueValid).withMessage('Should have a valid signature value'),
+  body('signature.type')
+    .optional()
+    .custom(isSignatureTypeValid).withMessage('Should have a valid signature type'),
+  body('signature.created')
+    .optional()
+    .custom(isDateValid).withMessage('Should have a valid signature created date'),
+  body('signature.creator')
+    .optional()
+    .custom(isSignatureCreatorValid).withMessage('Should have a valid signature creator'),
+  body('signature.signatureValue')
+    .optional()
+    .custom(isSignatureValueValid).withMessage('Should have a valid signature value'),
 
   (req: express.Request, res: express.Response, next: express.NextFunction) => {
     logger.debug('Checking activitypub signature parameter', { parameters: { signature: req.body.signature } })
-- 
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