Content-Security-Policy header

Availability

[SINCE Orbeon Forms 2018.1]

What is the Content-Security-Policy header?

The Content-Security-Policy HTTP header, also known as CSP header, is a relatively recent HTTP header which "helps to detect and mitigate certain types of attacks, including Cross Site Scripting (XSS) and data injection attacks".

Disabling inline scripts and CSS

Introduction

Some organizations set the Content-Security-Policy header to strict values which disallow inline JavaScript and CSS within HTML pages, for example with default-src 'self'.

Up until Orbeon Forms 2017.2, Orbeon Forms included some inline scripts and CSS in the HTML served to the browser. Disabling inline scripts and CSS with Content-Security-Policy with those Orbeon Forms versions will prevent Orbeon Forms from working correctly.

With Orbeon Forms 2018.1 and newer, Orbeon Forms no longer produces inline scripts and CSS by default, which allows for these strict values of the Content-Security-Policy header. While Orbeon Forms already takes measures against XSS and data injection, disabling the use of inline scripts can make Orbeon Forms even safer by default.

Configuration property

The following XForms property allows you to re-enable inline scripts and CSS. The default is false:

<property 
    as="xs:boolean" 
    name="oxf.xforms.inline-resources"                            
    value="true"/>

We recommend leaving the value to the default of false.

Generating the Content-Security-Policy header

In many cases, the Content-Security-Policy header is generated more globally by a reverse proxy or server.

But Orbeon Forms is able to produce that header as well, whether just for testing or for deployment. To enable this, simply uncomment the following entry in the Orbeon Forms WAR file's web.xml:

<init-param>
    <param-name>content-security-policy</param-name>
    <param-value>default-src 'self'; img-src 'self' data:</param-value>
</init-param>

You can set the param-value to any legal value supported by web browsers. In this example, default-src 'self' "Refers to the origin from which the protected document is being served, including the same URL scheme and port number. You must include the single quotes." (Mozilla)

NOTE: The content-security-policy name must remain in lowercase. It is a configuration parameter name, not the actual header name.