Re: [RFC][PATCH-2.4] Prevent mounting on ".."

On Sun, Jun 29, 2003 at 03:09:52PM +0200, Willy TARREAU wrote:
> chroot("/var/empty") (read-only directory or file-system)
> chdir("/")
> listen(), accept(), fork(), whatever...
> -> external code injection from a cracker :
>    mount("none", "..", "ramfs")
>    mkdir("../mydir")
>    chdir("../mydir")
>    the cracker now installs whatever he wants here.

That's a BS.  Same effect would be achieved by replacing ".." with ".".
Or mounting on any existing subdirectory.

If attacker can mount of chroot - you've LOST.  Already.  End of story.