Sanitize error input to prevent HTML/CSS injection in messages

Merge branch 'security-fix-html-css-injection-14-8' into '14-8-stable-ee'

See merge request gitlab-org/security/gitlab!2378

Changelog: security

lib/gitlab/ci/pipeline/chain/helpers.rb

@@ -6,25 +6,28 @@ module Gitlab
       module Chain
         module Helpers
           def error(message, config_error: false, drop_reason: nil)
+            sanitized_message = ActionController::Base.helpers.sanitize(message, tags: [])
+
             if config_error
               drop_reason = :config_error
-              pipeline.yaml_errors = message
+              pipeline.yaml_errors = sanitized_message
             end
-            pipeline.add_error_message(message)
+            pipeline.add_error_message(sanitized_message)
             drop_pipeline!(drop_reason)
             # TODO: consider not to rely on AR errors directly as they can be
             # polluted with other unrelated errors (e.g. state machine)
             # https://gitlab.com/gitlab-org/gitlab/-/issues/220823
-            pipeline.errors.add(:base, message)
+            pipeline.errors.add(:base, sanitized_message)
             pipeline.errors.full_messages
           end
           def warning(message)
-            pipeline.add_warning_message(message)
+            sanitized_message = ActionController::Base.helpers.sanitize(message, tags: [])
+            pipeline.add_warning_message(sanitized_message)
           end
           private

lib/gitlab/ci/pipeline/chain/validate/abilities.rb

@@ -23,7 +23,7 @@ module Gitlab
               end
               unless allowed_to_write_ref?
-                error("You do not have sufficient permission to run a pipeline on '#{command.ref}'. Please select a different branch or contact your administrator for assistance. <a href=https://docs.gitlab.com/ee/ci/pipelines/#pipeline-security-on-protected-branches>Learn more</a>".html_safe)
+                error("You do not have sufficient permission to run a pipeline on '#{command.ref}'. Please select a different branch or contact your administrator for assistance.")
               end
             end

spec/lib/gitlab/ci/pipeline/chain/helpers_spec.rb

@@ -22,6 +22,19 @@ RSpec.describe Gitlab::Ci::Pipeline::Chain::Helpers do
   let(:command) { double(save_incompleted: true) }
   let(:message) { 'message' }
+  describe '.warning' do
+    context 'when the warning includes malicious HTML' do
+      let(:message) { '<div>gimme your password</div>' }
+      let(:sanitized_message) { 'gimme your password' }
+
+      it 'sanitizes' do
+        subject.warning(message)
+
+        expect(pipeline.warning_messages[0].content).to include(sanitized_message)
+      end
+    end
+  end
+
   describe '.error' do
     shared_examples 'error function' do
       specify do
@@ -36,6 +49,18 @@ RSpec.describe Gitlab::Ci::Pipeline::Chain::Helpers do
       end
     end
+    context 'when the error includes malicious HTML' do
+      let(:message) { '<div>gimme your password</div>' }
+      let(:sanitized_message) { 'gimme your password' }
+
+      it 'sanitizes the error and removes the HTML tags' do
+        subject.error(message, config_error: true, drop_reason: :config_error)
+
+        expect(pipeline.yaml_errors).to eq(sanitized_message)
+        expect(pipeline.errors[:base]).to include(sanitized_message)
+      end
+    end
+
     context 'when given a drop reason' do
       context 'when config error is true' do
         context 'sets the yaml error and overrides the drop reason' do