Don't process ActivityPub payload if signature is invalid (#4752)

* Don't process ActivityPub payload if signature is invalid

* Fix style issue

1 files changed, 46 insertions, 1 deletions

diff --git a/spec/services/activitypub/process_collection_service_spec.rb b/spec/services/activitypub/process_collection_service_spec.rb
index bf3bc82aa..249b12470 100644
--- a/spec/services/activitypub/process_collection_service_spec.rb
+++ b/spec/services/activitypub/process_collection_service_spec.rb
@@ -1,10 +1,55 @@
 require 'rails_helper'
 
 RSpec.describe ActivityPub::ProcessCollectionService do
+  let(:actor) { Fabricate(:account) }
+
+  let(:payload) do
+    {
+      '@context': 'https://www.w3.org/ns/activitystreams',
+      id: 'foo',
+      type: 'Create',
+      actor: ActivityPub::TagManager.instance.uri_for(actor),
+      object: {
+        id: 'bar',
+        type: 'Note',
+        content: 'Lorem ipsum',
+      },
+    }
+  end
+
+  let(:json) { Oj.dump(payload) }
+
   subject { described_class.new }
 
   describe '#call' do
     context 'when actor is the sender'
-    context 'when actor differs from sender'
+    context 'when actor differs from sender' do
+      let(:forwarder) { Fabricate(:account) }
+
+      it 'processes payload with sender if no signature exists' do
+        expect_any_instance_of(ActivityPub::LinkedDataSignature).not_to receive(:verify_account!)
+        expect(ActivityPub::Activity).to receive(:factory).with(instance_of(Hash), forwarder)
+
+        subject.call(json, forwarder)
+      end
+
+      it 'processes payload with actor if valid signature exists' do
+        payload['signature'] = {'type' => 'RsaSignature2017'}
+
+        expect_any_instance_of(ActivityPub::LinkedDataSignature).to receive(:verify_account!).and_return(actor)
+        expect(ActivityPub::Activity).to receive(:factory).with(instance_of(Hash), actor)
+
+        subject.call(json, forwarder)
+      end
+
+      it 'does not process payload if invalid signature exists' do
+        payload['signature'] = {'type' => 'RsaSignature2017'}
+
+        expect_any_instance_of(ActivityPub::LinkedDataSignature).to receive(:verify_account!).and_return(nil)
+        expect(ActivityPub::Activity).not_to receive(:factory)
+
+        subject.call(json, forwarder)
+      end
+    end
   end
 end