Re: Jailed sysvipc implementation.

From: Dmitry Sivachenko (demon_at_FreeBSD.org)
Date: 06/25/03

  • Next message: Robert Watson: "Re: Jailed sysvipc implementation." 
    Date: Wed, 25 Jun 2003 19:46:27 +0400
To: Pawel Jakub Dawidek <nick@garage.freebsd.pl>

    On Wed, Jun 25, 2003 at 05:31:53PM +0200, Pawel Jakub Dawidek wrote:
    > On Wed, Jun 25, 2003 at 07:21:19PM +0400, Dmitry Sivachenko wrote:
    > +> > +> > But you got still *one* memory zones for every jail and main host.
    > +> > +>
    > +> > +> Yes, that is exactly what I want.
    > +> > +> This is similar to separate IP stack for each jail: this is more powerful
    > +> > +> solution, but more expensive (uses more kernel memory).
    > +> >
    > +> > But note that my implementation allocates memory "on demand".
    > +>
    > +> This is part of the problem: with single memory zone for all jails,
    > +> less memory is allocated. With private memory zones, if m jails use IPC,
    > +> you need to allocate m*M kbytes (for some value of M you consider
    > +> sufficient for one jail).
    > +>
    > +> With one memory zone for all jails, it is enough to allocate N kbytes where
    > +> M < N < m*M, because every jail will not use all M kbytes at the same time.
    >
    > Of course, but please. We could start wondering if struct prison in every
    > ucred struct don't consume to much memory. Of course we allocate more memory,

    Common sence is your friend.

    > but if we want to run for example two instants of postgresql in two
    > diffrent jails?

    I propose to add additional checks for p->p_prison. If two
    different users (with different UIDs) can use IPC, then it is simple to
    allow processes from different jails to use it too (and do not
    interfere with each other).

    >
    > But ok, it will be good compromise to add sysctl security.jail.privipc IMHO.
    > So we could turn this feature on if it is needed. What is your opinion?
    >

    My point of view is that allowing jailed processes to safely use single
    memory zone is simple and sufficient solution.

    _______________________________________________
    freebsd-arch@freebsd.org mailing list
    http://lists.freebsd.org/mailman/listinfo/freebsd-arch
    To unsubscribe, send any mail to "freebsd-arch-unsubscribe@freebsd.org"

  • Next message: Robert Watson: "Re: Jailed sysvipc implementation."