Add a Content Security Policy

config/initializers/content_security_policy.rb

@@ -6,28 +6,57 @@
 # For further information see the following documentation
 # https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy
 
-# Rails.application.config.content_security_policy do |policy|
-#   # If you are using webpack-dev-server then specify webpack-dev-server host
-#   policy.connect_src :self, :https, "http://localhost:3035", "ws://localhost:3035" if Rails.env.development?
+require_relative 'sentry_csp'
+require_relative 'sentry_javascript'
 
-#   policy.default_src :self, :https
-#   policy.font_src    :self, :https, :data
-#   policy.img_src     :self, :https, :data
-#   policy.object_src  :none
-#   policy.script_src  :self, :https
-#   policy.style_src   :self, :https
-#   # If you are using webpack-dev-server then specify webpack-dev-server host
-#   policy.connect_src :self, :https, "http://localhost:3035", "ws://localhost:3035" if Rails.env.development?
+def self.apply_yml_settings_for(policy)
+  csp_settings = CodeOcean::Config.new(:content_security_policy)
 
-#   # Specify URI for violation reports
-#   # policy.report_uri "/csp-violation-report-endpoint"
-# end
+  csp_settings.read.each do |directive, additional_settings|
+    existing_settings = if directive == 'report_uri'
+                          ''
+                        else
+                          policy.public_send(directive) || []
+                        end
+    all_settings = existing_settings + additional_settings
+    policy.public_send(directive, *all_settings)
+  end
+end
+
+def self.apply_sentry_settings_for(policy)
+  sentry_domain = URI.parse SentryJavascript.dsn
+  additional_setting = "#{sentry_domain.scheme}://#{sentry_domain.host}"
+  existing_settings = policy.connect_src || []
+  all_settings = existing_settings + [additional_setting]
+  policy.connect_src(*all_settings)
+end
+
+Rails.application.config.content_security_policy do |policy|
+  policy.default_src          :none
+  policy.base_uri             :none
+  policy.font_src             :self
+  # Code executions might return a base64 encoded image as a :data URI
+  policy.img_src              :self, :data
+  policy.object_src           :none
+  policy.script_src           :self, :report_sample
+  # Our ACE editor unfortunately requires :unsafe_inline for the code highlighting
+  policy.style_src            :self, :unsafe_inline, :report_sample
+  policy.connect_src          :self
+  policy.form_action          :self
+  policy.frame_ancestors      :none
+
+  # Specify URI for violation reports
+  policy.report_uri           SentryCsp.report_url if SentryCsp.active?
+
+  apply_yml_settings_for      policy
+  apply_sentry_settings_for   policy if SentryJavascript.active?
+end
 
 # If you are using UJS then enable automatic nonce generation
-# Rails.application.config.content_security_policy_nonce_generator = -> request { SecureRandom.base64(16) }
+Rails.application.config.content_security_policy_nonce_generator = ->(request) { request.session.id.to_s }
 
 # Set the nonce only to specific directives
-# Rails.application.config.content_security_policy_nonce_directives = %w(script-src)
+Rails.application.config.content_security_policy_nonce_directives = %w[script-src]
 
 # Report CSP violations to a specified URI
 # For further information see the following documentation: