content_security_policy_nonce calls Rails method so CSP does not contain nonce

[jdudley1123]

Expected outcome

I am using GoodJob to process jobs on Rails 6. The GoodJob dashboard includes a number of scripts and styles. These all have nonces set using the content_security_policy_nonce method.

 <%= tag.script "", src: frontend_static_path(:bootstrap, format: :js, v: GoodJob::VERSION, locale: nil), nonce: content_security_policy_nonce %>

(link to code)

I would expect Secure Headers to set the nonce in the CSP header so that these scripts are permitted.

Actual outcome

No nonce is set in the CSP header. I think that Rails' own content_security_policy_nonce method is being called rather than the Secure Headers method of the same name. This means that the CSP set by Secure Headers doesn't include the nonce, and the scripts and styles are therefore not permitted.

I know that recommend practice when using Secure Headers is to use the nonced_javascript_tag method, but since this is in a gem I can't do that.

Possible related issues:

• Method conflicting content_security_policy_nonce with Rails 5.2 #392
• Avoid calling content_security_policy_nonce internally #389

Config

SecureHeaders::Configuration.default do |config|
  config.hsts = "max-age=#{1.year.to_i}; includeSubDomains; preload"
  config.x_frame_options = 'DENY'
  config.x_content_type_options = 'nosniff'
  config.x_xss_protection = '1; mode=block'
  config.x_download_options = 'noopen'
  config.x_permitted_cross_domain_policies = 'none'
  config.referrer_policy = %w[origin-when-cross-origin
                              strict-origin-when-cross-origin]
  config.csp = {
    default_src: %w['none'],
    script_src: %w['self' http://www.google-analytics.com],
    connect_src: %w['self'],
    frame_ancestors: %w['none'],
    font_src: %w['self' data: https://fonts.gstatic.com],
    img_src: %w['self' data: https://validator.swagger.io],
    style_src: %w['self' https://fonts.googleapis.com],
  }
end

Generated headers

default-src 'none'; connect-src 'self'; font-src 'self' data: fonts.gstatic.com; frame-ancestors 'none'; img-src 'self' data: validator.swagger.io; script-src 'self' www.google-analytics.com; style-src 'self' fonts.googleapis.com