DISCOURSE_CDN_URL causes content security policy violations?

xrav3nz · February 6, 2020, 11:11pm

So we have this in the CSP

https://abedmulti-92e2.kxcdn.com/uploads/assets/ 
https://abedmulti-92e2.kxcdn.com/uploads/brotli_asset/
# i.e. DISCOURSE_S3_CDN_URL + /brotli_asset/

But the actual address is

https://lcsupport-92e2.kxcdn.com/brotli_asset/preload-store-d32dcf974dddcac742f8a7a6aa7fcd686185920b201029d0ecb2b85527ef9034.js
# i.e. DISCOURSE_CDN_URL + /brotli_asset/...

The relevant CSP code:

github.com/discourse/discourse

lib/content_security_policy/default.rb

49843f327


      
            # [dir, can_use_s3_cdn, can_use_cdn]
            ['/assets/',             true, true],
            ['/brotli_asset/',       true, true],
            ['/extra-locales/',      false, false],
            ['/highlight-js/',       false, true],
            ['/javascripts/',        false, true],
            ['/plugins/',            false, true],
            ['/theme-javascripts/',  false, true],
            ['/svg-sprite/',         false, true],
          ]
          
          def script_assets(base = base_url, s3_cdn = GlobalSetting.s3_cdn_url, cdn = GlobalSetting.cdn_url)
            SCRIPT_ASSET_DIRECTORIES.map do |dir, can_use_s3_cdn, can_use_cdn|
              if can_use_s3_cdn && s3_cdn
                s3_cdn + dir
              elsif can_use_cdn && cdn
                cdn + dir
              else
                base + dir
              end

We prioritize using DISCOURSE_S3_CDN_URL for assets when available. This aligns with the CDN asset URL generation.

@pfaffman Does GlobalSetting.use_s3? return true for your site?

I wonder if we need an additional GlobalSetting.use_s3? check here. Does having GlobalSetting.s3_cdn_url necessarily imply GlobalSetting.use_s3?? I’m a bit hazy with asset genereation / S3 CDN now could someone more familiar with it also take a look? Thanks!

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DISCOURSE_CDN_URL causes content security policy violations?

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