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

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Message-ID: <20130819184355.GA25362@redhat.com>
Date:	Mon, 19 Aug 2013 20:43:55 +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 08/19, 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().

Oleg.

--- x/kernel/fork.c
+++ x/kernel/fork.c
@@ -1176,7 +1176,7 @@ static struct task_struct *copy_process(
 	 * If the new process will be in a different pid namespace
 	 * don't allow the creation of threads.
 	 */
-	if ((clone_flags & (CLONE_VM|CLONE_NEWPID)) &&
+	if ((clone_flags & (CLONE_THREAD | CLONE_PARENT | CLONE_NEWPID)) &&
 	    (task_active_pid_ns(current) != current->nsproxy->pid_ns))
 		return ERR_PTR(-EINVAL);
 

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