Fix insufficient origin validation

app/controllers/concerns/signature_verification.rb

@@ -157,7 +157,7 @@ def account_from_key_id(key_id)
       stoplight_wrap_request { ResolveAccountService.new.call(key_id.gsub(/\Aacct:/, '')) }
     elsif !ActivityPub::TagManager.instance.local_uri?(key_id)
       account   = ActivityPub::TagManager.instance.uri_to_resource(key_id, Account)
-      account ||= stoplight_wrap_request { ActivityPub::FetchRemoteKeyService.new.call(key_id, id: false) }
+      account ||= stoplight_wrap_request { ActivityPub::FetchRemoteKeyService.new.call(key_id) }
       account
     end
   rescue Mastodon::HostValidationError

app/helpers/jsonld_helper.rb

@@ -63,8 +63,8 @@ def canonicalize(json)
     graph.dump(:normalize)
   end
 
-  def fetch_resource(uri, id, on_behalf_of = nil)
-    unless id
+  def fetch_resource(uri, id_is_known, on_behalf_of = nil, request_options: {})
+    unless id_is_known
       json = fetch_resource_without_id_validation(uri, on_behalf_of)
 
       return unless json

app/lib/activitypub/activity.rb

@@ -168,7 +168,7 @@ def follow_from_object
   def fetch_remote_original_status
     if object_uri.start_with?('http')
       return if ActivityPub::TagManager.instance.local_uri?(object_uri)
-      ActivityPub::FetchRemoteStatusService.new.call(object_uri, id: true, on_behalf_of: @account.followers.local.first)
+      ActivityPub::FetchRemoteStatusService.new.call(object_uri, on_behalf_of: @account.followers.local.first)
     elsif @object['url'].present?
       ::FetchRemoteStatusService.new.call(@object['url'])
     end

app/lib/activitypub/linked_data_signature.rb

@@ -18,8 +18,8 @@ def verify_account!
 
     return unless type == 'RsaSignature2017'
 
-    creator   = ActivityPub::TagManager.instance.uri_to_resource(creator_uri, Account)
-    creator ||= ActivityPub::FetchRemoteKeyService.new.call(creator_uri, id: false)
+    creator = ActivityPub::TagManager.instance.uri_to_resource(creator_uri, Account)
+    creator = ActivityPub::FetchRemoteKeyService.new.call(creator_uri) if creator&.public_key.blank?
 
     return if creator.nil?
 

app/services/activitypub/fetch_remote_account_service.rb

@@ -7,15 +7,15 @@ class ActivityPub::FetchRemoteAccountService < BaseService
   SUPPORTED_TYPES = %w(Application Group Organization Person Service).freeze
 
   # Does a WebFinger roundtrip on each call, unless `only_key` is true
-  def call(uri, id: true, prefetched_body: nil, break_on_redirect: false, only_key: false)
+  def call(uri, prefetched_body: nil, break_on_redirect: false, only_key: false)
     return if domain_not_allowed?(uri)
     return ActivityPub::TagManager.instance.uri_to_resource(uri, Account) if ActivityPub::TagManager.instance.local_uri?(uri)
 
     @json = begin
       if prefetched_body.nil?
-        fetch_resource(uri, id)
+        fetch_resource(uri, true)
       else
-        body_to_json(prefetched_body, compare_id: id ? uri : nil)
+        body_to_json(prefetched_body, compare_id: uri)
       end
     end
 

app/services/activitypub/fetch_remote_key_service.rb

@@ -4,21 +4,10 @@ class ActivityPub::FetchRemoteKeyService < BaseService
   include JsonLdHelper
 
   # Returns account that owns the key
-  def call(uri, id: true, prefetched_body: nil)
-    if prefetched_body.nil?
-      if id
-        @json = fetch_resource_without_id_validation(uri)
-        if person?
-          @json = fetch_resource(@json['id'], true)
-        elsif uri != @json['id']
-          return
-        end
-      else
-        @json = fetch_resource(uri, id)
-      end
-    else
-      @json = body_to_json(prefetched_body, compare_id: id ? uri : nil)
-    end
+  def call(uri)
+    return if uri.blank?
+
+    @json = fetch_resource(uri, false)
 
     return unless supported_context?(@json) && expected_type?
     return find_account(@json['id'], @json) if person?

app/services/activitypub/fetch_remote_status_service.rb

@@ -4,19 +4,19 @@ class ActivityPub::FetchRemoteStatusService < BaseService
   include JsonLdHelper
 
   # Should be called when uri has already been checked for locality
-  def call(uri, id: true, prefetched_body: nil, on_behalf_of: nil)
+  def call(uri, prefetched_body: nil, on_behalf_of: nil)
     @json = begin
       if prefetched_body.nil?
-        fetch_resource(uri, id, on_behalf_of)
+        fetch_resource(uri, true, on_behalf_of)
       else
-        body_to_json(prefetched_body, compare_id: id ? uri : nil)
+        body_to_json(prefetched_body, compare_id: uri)
       end
     end
 
     return if !(supported_context? && expected_type?) || actor_id.nil? || !trustworthy_attribution?(@json['id'], actor_id)
 
     actor = ActivityPub::TagManager.instance.uri_to_resource(actor_id, Account)
-    actor = ActivityPub::FetchRemoteAccountService.new.call(actor_id, id: true) if actor.nil? || needs_update?(actor)
+    actor = ActivityPub::FetchRemoteAccountService.new.call(actor_id) if actor.nil? || needs_update?(actor)
 
     return if actor.nil? || actor.suspended?
 

app/services/activitypub/process_account_service.rb

@@ -190,7 +190,7 @@ def collection_total_items(type)
 
   def moved_account
     account   = ActivityPub::TagManager.instance.uri_to_resource(@json['movedTo'], Account)
-    account ||= ActivityPub::FetchRemoteAccountService.new.call(@json['movedTo'], id: true, break_on_redirect: true)
+    account ||= ActivityPub::FetchRemoteAccountService.new.call(@json['movedTo'], break_on_redirect: true)
     account
   end
 

app/services/fetch_resource_service.rb

@@ -33,7 +33,15 @@ def process_response(response, terminal = false)
       body = response.body_with_limit
       json = body_to_json(body)
 
-      [json['id'], { prefetched_body: body, id: true }] if supported_context?(json) && (equals_or_includes_any?(json['type'], ActivityPub::FetchRemoteAccountService::SUPPORTED_TYPES) || expected_type?(json))
+      return unless supported_context?(json) && (equals_or_includes_any?(json['type'], ActivityPub::FetchRemoteAccountService::SUPPORTED_TYPES) || expected_type?(json))
+
+      if json['id'] != @url
+        return if terminal
+
+        return process(json['id'], terminal: true)
+      end
+
+      [@url, { prefetched_body: body }]
     elsif !terminal
       link_header = response['Link'] && parse_link_header(response)
 

spec/services/activitypub/fetch_remote_account_service_spec.rb

@@ -16,7 +16,7 @@
   end
 
   describe '#call' do
-    let(:account) { subject.call('https://example.com/alice', id: true) }
+    let(:account) { subject.call('https://example.com/alice') }
 
     shared_examples 'sets profile data' do
       it 'returns an account' do

spec/services/fetch_resource_service_spec.rb

@@ -46,7 +46,7 @@
 
       let(:json) do
         {
-          id: 1,
+          id: 'http://example.com/foo',
           '@context': ActivityPub::TagManager::CONTEXT,
           type: 'Note',
         }.to_json
@@ -71,14 +71,14 @@
         let(:content_type) { 'application/activity+json; charset=utf-8' }
         let(:body) { json }
 
-        it { is_expected.to eq [1, { prefetched_body: body, id: true }] }
+        it { is_expected.to eq ['http://example.com/foo', { prefetched_body: body }] }
       end
 
       context 'when content type is ld+json with profile' do
         let(:content_type) { 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"' }
         let(:body) { json }
 
-        it { is_expected.to eq [1, { prefetched_body: body, id: true }] }
+        it { is_expected.to eq ['http://example.com/foo', { prefetched_body: body }] }
       end
 
       before do
@@ -89,14 +89,14 @@
       context 'when link header is present' do
         let(:headers) { { 'Link' => '<http://example.com/foo>; rel="alternate"; type="application/activity+json"', } }
 
-        it { is_expected.to eq [1, { prefetched_body: json, id: true }] }
+        it { is_expected.to eq ['http://example.com/foo', { prefetched_body: json }] }
       end
 
       context 'when content type is text/html' do
         let(:content_type) { 'text/html' }
         let(:body) { '<html><head><link rel="alternate" href="http://example.com/foo" type="application/activity+json"/></head></html>' }
 
-        it { is_expected.to eq [1, { prefetched_body: json, id: true }] }
+        it { is_expected.to eq ['http://example.com/foo', { prefetched_body: json }] }
       end
     end
   end