Re: [PATCH 3/3] fork: unify and tighten up CLONE_NEWUSER/CLONE_NEWPID checks

From: Andy Lutomirski <luto@amacapital.net>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Brad Spengler <spender@grsecurity.net>,
	Colin Walters <walters@redhat.com>,
	Pavel Emelyanov <xemul@parallels.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] fork: unify and tighten up CLONE_NEWUSER/CLONE_NEWPID checks
Date: Thu, 22 Aug 2013 12:11:31 -0700	[thread overview]
Message-ID: <CALCETrVT4r3G9tQpt4y22iB+y-fw5piH93OOn9wfvSd8xQdDBw@mail.gmail.com> (raw)
In-Reply-To: <20130822183250.GA23769@redhat.com>

On Thu, Aug 22, 2013 at 11:32 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> On 08/22, Andy Lutomirski wrote:
>>
>> On Thu, Aug 22, 2013 at 11:15 AM, Oleg Nesterov <oleg@redhat.com> wrote:
>> >
>> > Yes. Before this patch do_fork() did:
>> >
>> >         if (clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) {
>> >                 if (clone_flags & (CLONE_THREAD|CLONE_PARENT))
>> >                         return -EINVAL;
>> >         }
>> >
>> > however, let me repeat, CLONE_PARENT after unshare(CLONE_NEWPID) was
>> > allowed. With this patch CLONE_PARENT is nacked in both cases.
>>
>> Is this -stable-worthy?
>
> Honestly, I do not know. I do not want to abuse -stable, and I will
> sleep better if this patch won't go into the stable trees ;)
>
> OTOH, I think that at least 1/3 is probably -stable material... Since
> I am going to send v2, I would not mind to add stable@vger.kernel.org
> if both you and Eric agree.

This may allow creation of a process with tgid and pid in different
pid namespaces.  If so, I have no idea what the consequences would be.

>
> Oleg.
>

-- 
Andy Lutomirski
AMA Capital Management, LLC