thujal said

The same website works fine in Firefox/Windows

Not for me, I get this in the Web Console on Firefox 48.0.2/Windows:

Content Security Policy: The page's settings blocked the loading of a resource at https://go-web.goodyear.portal.mccannbristol.co.uk/a/svg/global.svg ("default-src 'none'").

(I get a bouncing span with no image in it in the Inspector.)

This implies that a more specific policy applicable to the image in the SVG element was not found. But... extensive searching has not turned up an explanation of what <svg><img></svg> <svg><use href="uri"></svg> requires.

In your CSP, this is the only other 'none', did you try:

object-src 'self';

Yes, we have tried object-src. In fact, we've kept adding the different src elements in a bid to make this work, but it does not. For example:

Header always set Content-Security-Policy "default-src 'none'; script-src 'self' https://www.google-analytics.com; connect-src 'self'; frame-src 'self' https://*.youtube.com https://*.youtube-nocookie.com https://*.doubleclick.net; style-src 'self' 'unsafe-inline'; img-src 'self' data: https://www.google-analytics.com https://stats.g.doubleclick.net; object-src 'self'; font-src 'self'; media-src 'self'; child-src 'self'; plugin-types 'image/svg+xml'; frame-ancestors 'self'"

Does not work.

However, setting a default-src of self does indeed work:

Header always set Content-Security-Policy "default-src 'self'; script-src 'self' https://www.google-analytics.com; connect-src 'self'; frame-src 'self' https://*.youtube.com https://*.youtube-nocookie.com https://*.doubleclick.net; style-src 'self' 'unsafe-inline'; img-src 'self' data: https://www.google-analytics.com https://stats.g.doubleclick.net;"

Checking [https://content-security-policy.com|h.../content-security-policy.com] and other documentation, it doesn't look like there are any more headers for us to try to bring these SVG's in, so I simply see no way to have SVGs work in FF on a site with Content-Security-Policy "default-src 'none'... Which can't be the case, can it? I must be missing something really obvious!

Oh, and apologies, it also does not work in FF / win, this was an error our on testers part!

I had trouble figuring out which part of the source code applies different content policies to different content types. If you or someone with you can search it out, that might shed light on how svg is evaluated.

https://dxr.mozilla.org/mozilla-release/source/

Alternately, you could submit a new bug:

https://bugzilla.mozilla.org/enter_bug.cgi

https://bugzilla.mozilla.org/show_bug.cgi?id=1303364 :)