From a41ad0254ecf1539201b675008307ff3ca672a8a Mon Sep 17 00:00:00 2001
From: Stefan Neuhaus <stefan@stefanneuhaus.org>
Date: Sun, 27 May 2018 23:20:39 +0200
Subject: [PATCH] Add a BlackFriday option for rel="noreferrer" on external
 links

Add a configuration option "noreferrerLinks". When set to "true" the "HTML_NOREFERRER_LINKS" flag is being passed to Blackfriday. Thereby all *absolute* links will get a "noreferrer" value for their "rel" attribute.

See #4722
---
 content/en/readfiles/bfconfig.md | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/content/en/readfiles/bfconfig.md b/content/en/readfiles/bfconfig.md
index a7e74566a..936aef52d 100644
--- a/content/en/readfiles/bfconfig.md
+++ b/content/en/readfiles/bfconfig.md
@@ -48,6 +48,11 @@
     Blackfriday flag: **`HTML_NOFOLLOW_LINKS`** <br>
     Purpose: `true` creates <s>external links</s> **absolute** links with `nofollow` being added to their `rel` attribute. Thereby crawlers are advised to not follow the link. While the `rel="nofollow"` attribute is typically used for external links, Blackfriday does that for _all_ absolute links. One needs to make note of this if they use absolute links throughout, for internal links too (for example, by setting `canonifyURLs` to `true` or via `absURL`).
 
+`noreferrerLinks`
+: default: **`false`** <br>
+    Blackfriday flag: **`HTML_NOREFERRER_LINKS`** <br>
+    Purpose: `true` creates <s>external links</s> **absolute** links with `noreferrer` being added to their `rel` attribute. Thus when following the link no referrer information will be leaked. While the `rel="noreferrer"` attribute is typically used for external links, Blackfriday does that for _all_ absolute links. One needs to make note of this if they use absolute links throughout, for internal links too (for example, by setting `canonifyURLs` to `true` or via `absURL`).
+
 `plainIDAnchors`
 : default **`true`** <br>
     Blackfriday flag: **`FootnoteAnchorPrefix` and `HeaderIDSuffix`** <br>