linux-kernel - Re: PATCH? fix unshare(NEWPID) && vfork()

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20130820185043.GA24040@redhat.com>
Date:	Tue, 20 Aug 2013 20:50:43 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Brad Spengler <spender@...ecurity.net>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Colin Walters <walters@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: PATCH? fix unshare(NEWPID) && vfork()

On 08/20, Andy Lutomirski wrote:
>
> On Mon, Aug 19, 2013 at 11:43 AM, Oleg Nesterov <oleg@...hat.com> wrote:
> > On 08/19, Andy Lutomirski wrote:
> >>
> >> On Mon, Aug 19, 2013 at 11:33 AM, Oleg Nesterov <oleg@...hat.com> wrote:
> >> >
> >> > So do you think this change is fine or not (ignoring the fact it needs
> >> > cleanups) ?
> >>
> >> I think that removing the CLONE_VM check is fine (although there are
> >> some other ones that should probably be removed as well), but I'm not
> >> sure if that check needs replacing with something else.
> >
> > OK, thanks... but I still can't understand.
> >
> > The patch I sent is equivalent to the new one below. I just tried to
> > unify it with another check in do_fork().
>
> I was confused.

Andy, I do not know how much you were confused, but I bet I am confused
much more ;)

> Currently (with or without your patch), vfork() followed by
> unshare(CLONE_NEWUSER) or unshare(CLONE_NEWPID) will unshare the VM.

Could you spell please?

We never unshare the VM. CLONE_VM in sys_unshare() paths just means
"fail unless ->mm is not shared".

Oleg.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/