Re: [PATCH 2.6.13.1] Patch for invisible threads

Al Viro
2005-09-13T21:57:13Z

On Tue, Sep 13, 2005 at 04:30:43PM -0500, Sripathi Kodi wrote:
> Al Viro wrote:
> >
> >Well... If exposing the list of tasks in a group is OK, we can just leave
> >->permission NULL for that sucker. If it's not (and arguably it can be
> >sensitive information), we have a bigger problem - right now chroot
> >boundary
> >is the only control we have there; normally anyone can ls
> >/proc/<whatever>/task
> >and see other threads.
> >
>
> Al, I understand that we can't set ->permission to NULL as it removes the
> chroot boundary check. If I understood you correctly, we need to put
> additional checks in proc_permission to ensure anyone doing ls
> /proc/<pid>/task won't be able to see other threads.

Wrong. We need a separate function, _not_ modifying proc_permssion().
If we need ->permission() at all, that is - note that anyone can do
ls /proc/<pid>/task on other users' process.