Prevent .no_delete from deleting

[smartcall]

Hello,

I was experiencing a lot of problems when my users were able to delete their /log directory despite of .no_delete file in it.
As a matter of fact (especially in my server setup) every user who is with 'administrator' status owns his /log directory and .no_delete file respectively. There was no reason why they couldn't delete this file and the whole directory, which prevented apache from starting again.

What I did was:

Edited /root/ispconfig/scripts/lib/config.lib.php
and added

$root_gruppe = $mod->system->root_group();
  exec("chmod 400 $web_path/user/.no_delete");
  exec("chown root:$root_gruppe $web_path/user/.no_delete");
  exec("chmod 400 $web_path/log/.no_delete");
  exec("chown root:$root_gruppe $web_path/log/.no_delete");
  exec("chmod 400 $web_path/cgi-bin/.no_delete");
  exec("chown root:$root_gruppe $web_path/cgi-bin/.no_delete");
  exec("chmod 400 $web_path/ssl/.no_delete");
  exec("chown root:$root_gruppe $web_path/ssl/.no_delete");
  exec("chmod 400 $web_path/phptmp/.no_delete");
  exec("chown root:$root_gruppe $web_path/phptmp/.no_delete");
  exec("chmod 400 $web_path/web/error/.no_delete");
  exec("chown root:$root_gruppe $web_path/web/error/.no_delete");

right after

exec("chown -R $user_username $web_path/log/* &> /dev/null");

in the section that follows after

////////// Verzeichnisse erzeugen ENDE ///////////

then i executed the command

find . -name ".no_delete" -exec chown root:root '{}' \;

in /var/www - where ISPConfig creates the webs in my server setup, just to make sure all previously created .no_delete files are owned by root.
That I believe solved my problem.

[smartcall]

Of course the above didn't work, because the owner still has write permissions on the containing directory.

Any ideas are appreciated.

[smartcall]

Again answering to myself, I think I finally managed to do it.

The permissions of the log dir itself must be 555. This way it works.
The .no_delete and directory can't be deleted.

[smartcall]

Another solution would be to add this in proftpd.conf

<Directory /var/www>
HideFiles (\.passwd|htpasswd|no_delete|forward|procmailrc|spamassassin|vacation.cache|Maildir|csc|antivirus.rc|autoresponder.r
c|html-trap.rc|local-rules.rc|mailsize.rc|quota.rc|spamassassin.rc|user_prefs|vacation.msg)$ #
</Directory>

Where directory is the top one for webs.

I gues that when proftpd doesn't show these files, their containing directories can't be deleted.
But i can't guarantee that this will work with all FTP clients.