Under Samba 3.4.7 and before, symlinks pose a problem. With
unix extensions = yes follow symlinks = yes wide symlinks = no
it is possible to do
jurjen@smb-client:~$ ln -s self-referential
ln: creating symbolic link `./self-referential': Not a directory
jurjen@smb-client:~$ ls -trl
ls: cannot access self-referential: Not a directory
l????????? ? ? ? ? ? self-referential
jurjen@smb-client:~$ rm -f self-referential
jurjen@smb-client:~$ ls -trl
ls: cannot access self-referential: Not a directory
l????????? ? ? ? ? ? self-referential
No settings I know of will give us symbolic links but prevent creation of self-referential symbolic links. And no setting that I know of will allow us to delete self-referential links.