Don't display badges when builds are restricted

Badges were leaked to unauthorized users even when Public Builds
project setting is disabled.

Added guard clause to the controller to check if user can read
build.

app/controllers/projects/badges_controller.rb

@@ -3,7 +3,8 @@
 class Projects::BadgesController < Projects::ApplicationController
   layout 'project_settings'
   before_action :authorize_admin_project!, only: [:index]
-  before_action :no_cache_headers, except: [:index]
+  before_action :no_cache_headers, only: [:pipeline, :coverage]
+  before_action :authorize_read_build!, only: [:pipeline, :coverage]
 
   def pipeline
     pipeline_status = Gitlab::Badge::Pipeline::Status

changelogs/unreleased/security-fix-badges-leaked-to-unauthorized-users.yml

+---
+title: Show badges if pipelines are public otherwise default to project permissions.
+erge_request:
+author:
+type: security

spec/controllers/projects/badges_controller_spec.rb

@@ -7,51 +7,115 @@ describe Projects::BadgesController do
   let!(:pipeline) { create(:ci_empty_pipeline) }
   let(:user) { create(:user) }
 
-  before do
-    project.add_maintainer(user)
-    sign_in(user)
-  end
+  shared_examples 'a badge resource' do |badge_type|
+    context 'when pipelines are public' do
+      before do
+        project.update!(public_builds: true)
+      end
+
+      context 'when project is public' do
+        before do
+          project.update!(visibility_level: Gitlab::VisibilityLevel::PUBLIC)
+        end
+
+        it "returns the #{badge_type} badge to unauthenticated users" do
+          get_badge(badge_type)
+
+          expect(response).to have_gitlab_http_status(:ok)
+        end
+      end
+
+      context 'when project is restricted' do
+        before do
+          project.update!(visibility_level: Gitlab::VisibilityLevel::INTERNAL)
+          project.add_guest(user)
+          sign_in(user)
+        end
+
+        it "returns the #{badge_type} badge to guest users" do
+          get_badge(badge_type)
+
+          expect(response).to have_gitlab_http_status(:ok)
+        end
+      end
+    end
 
-  it 'requests the pipeline badge successfully' do
-    get_badge(:pipeline)
+    context 'format' do
+      before do
+        project.add_maintainer(user)
+        sign_in(user)
+      end
 
-    expect(response).to have_gitlab_http_status(:ok)
-  end
+      it 'renders the `flat` badge layout by default' do
+        get_badge(badge_type)
 
-  it 'requests the coverage badge successfully' do
-    get_badge(:coverage)
+        expect(response).to render_template('projects/badges/badge')
+      end
 
-    expect(response).to have_gitlab_http_status(:ok)
-  end
+      context 'when style param is set to `flat`' do
+        it 'renders the `flat` badge layout' do
+          get_badge(badge_type, 'flat')
 
-  it 'renders the `flat` badge layout by default' do
-    get_badge(:coverage)
+          expect(response).to render_template('projects/badges/badge')
+        end
+      end
 
-    expect(response).to render_template('projects/badges/badge')
-  end
+      context 'when style param is set to an invalid type' do
+        it 'renders the `flat` (default) badge layout' do
+          get_badge(badge_type, 'xxx')
+
+          expect(response).to render_template('projects/badges/badge')
+        end
+      end
 
-  context 'when style param is set to `flat`' do
-    it 'renders the `flat` badge layout' do
-      get_badge(:coverage, 'flat')
+      context 'when style param is set to `flat-square`' do
+        it 'renders the `flat-square` badge layout' do
+          get_badge(badge_type, 'flat-square')
 
-      expect(response).to render_template('projects/badges/badge')
+          expect(response).to render_template('projects/badges/badge_flat-square')
+        end
+      end
     end
-  end
 
-  context 'when style param is set to an invalid type' do
-    it 'renders the `flat` (default) badge layout' do
-      get_badge(:coverage, 'xxx')
+    context 'when pipelines are not public' do
+      before do
+        project.update!(public_builds: false)
+      end
 
-      expect(response).to render_template('projects/badges/badge')
+      context 'when project is public' do
+        before do
+          project.update!(visibility_level: Gitlab::VisibilityLevel::PUBLIC)
+        end
+
+        it 'returns 404 to unauthenticated users' do
+          get_badge(badge_type)
+
+          expect(response).to have_gitlab_http_status(:not_found)
+        end
+      end
+
+      context 'when project is restricted to the user' do
+        before do
+          project.update!(visibility_level: Gitlab::VisibilityLevel::INTERNAL)
+          project.add_guest(user)
+          sign_in(user)
+        end
+
+        it 'defaults to project permissions' do
+          get_badge(:coverage)
+
+          expect(response).to have_gitlab_http_status(:not_found)
+        end
+      end
     end
   end
 
-  context 'when style param is set to `flat-square`' do
-    it 'renders the `flat-square` badge layout' do
-      get_badge(:coverage, 'flat-square')
+  describe '#pipeline' do
+    it_behaves_like 'a badge resource', :pipeline
+  end
 
-      expect(response).to render_template('projects/badges/badge_flat-square')
-    end
+  describe '#coverage' do
+    it_behaves_like 'a badge resource', :coverage
   end
 
   def get_badge(badge, style = nil)