The strict-dynamic CSP directive is supported in all our target browsers, and makes for a much simpler configuration. Instead of allowlisting paths, we use a per-request nonce to authorize `<script>` tags, and then those scripts are allowed to load additional scripts (or add additional inline scripts) without restriction.
This becomes especially useful when admins want to add external scripts like Google Tag Manager, or advertising scripts, which then go on to load a ton of other scripts.
All script tags introduced via themes will automatically have the nonce attribute applied, so it should be zero-effort for theme developers. Plugins *may* need some changes if they are inserting their own script tags.
This commit introduces a strict-dynamic-based CSP behind an experimental `content_security_policy_strict_dynamic` site setting.
This reverts commit 767b49232e.
If anything else (e.g. GTM integration) introduces a nonce/hash, then this change stops the splash screen JS to fail and makes sites unusable.
Browsers will ignore unsafe-inline if nonces or hashes are included in the CSP. When unsafe-inline is enabled, nonces and hashes are not required, so we can skip them.
Our strong recommendation remains that unsafe-inline should not be used in production.
Raw paths like `/test/path` are not supported natively in the CSP. This commit prepends the site's base URL to these paths. This allows plugins to add 'local' assets to the CSP without needing to hardcode the site's hostname.
- Define the CSP based on the requested domain / scheme (respecting force_https)
- Update EnforceHostname middleware to allow secondary domains, add specs
- Add URL scheme to anon cache key so that CSP headers are cached correctly
* FEATURE: allow plugins and themes to extend the default CSP
For plugins:
```
extend_content_security_policy(
script_src: ['https://domain.com/script.js', 'https://your-cdn.com/'],
style_src: ['https://domain.com/style.css']
)
```
For themes and components:
```
extend_content_security_policy:
type: list
default: "script_src:https://domain.com/|style_src:https://domain.com"
```
* clear CSP base url before each test
we have a test that stubs `Rails.env.development?` to true
* Only allow extending directives that core includes, for now
