[TASK] Allow access to visible content within /.well-known/ directory

Allow access to the visible content from within the `/.well-known/`
hidden directory. The access to all other hidden files and directories
(starting with a dot) is still blocked.

The /.well-known/ directory represents the standard (RFC 5785) path
prefix for "well-known locations", and therefore, access to its visible
content should not be blocked.

Resolves: #72712
Releases: master,7.6,6.2
Change-Id: I533d38a12da5cae59abed4fc00d597814d28fa04
Reviewed-on: https://review.typo3.org/45926


Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>

_.htaccess

@@ -282,7 +282,9 @@ AddDefaultCharset utf-8
 	RewriteRule ^(vendor|typo3_src) - [F]
 	RewriteRule (?:typo3conf/ext|typo3/sysext|typo3/ext)/[^/]+/(?:Configuration|Resources/Private|Tests?)/ - [F]
 
-	# Access block for files or folders starting with a dot
+	# Block access to all hidden files and directories with the exception of
+	# the visible content from within the `/.well-known/` hidden directory (RFC 5785).
+	RewriteCond %{REQUEST_URI} "!(^|/)\.well-known/([^./]+./?)+$" [NC]
 	RewriteCond %{SCRIPT_FILENAME} -d [OR]
 	RewriteCond %{SCRIPT_FILENAME} -f
 	RewriteRule (?:^|/)\. - [F]