From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1751432AbdJEQ1i (ORCPT <rfc822;w@1wt.eu>);
        Thu, 5 Oct 2017 12:27:38 -0400
Received: from mx1.redhat.com ([209.132.183.28]:43124 "EHLO mx1.redhat.com"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1751144AbdJEQ1h (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Thu, 5 Oct 2017 12:27:37 -0400
DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com EAC427EAA1
Authentication-Results: ext-mx04.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com
Authentication-Results: ext-mx04.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=oleg@redhat.com
Date: Thu, 5 Oct 2017 18:27:33 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: =?iso-8859-1?Q?J=FCrg?= Billeter <j@bitron.ch>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Michael Kerrisk <mtk.manpages@gmail.com>,
        Filipe Brandenburger <filbranden@google.com>,
        David Wilcox <davidvsthegiant@gmail.com>, hansecke@gmail.com,
        linux-kernel@vger.kernel.org
Subject: Re: [RESEND PATCH] prctl: add PR_[GS]ET_PDEATHSIG_PROC
Message-ID: <20171005162733.GA20068@redhat.com>
References: <20170909094008.49983-1-j@bitron.ch>
 <20170929123058.48924-1-j@bitron.ch>
 <20171002162041.a7cefe8af71327b8becd2347@linux-foundation.org>
 <87o9pogbf7.fsf@xmission.com>
 <1507013157.2304.48.camel@bitron.ch>
 <878tgse1c5.fsf@xmission.com>
 <1507050019.19102.51.camel@bitron.ch>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <1507050019.19102.51.camel@bitron.ch>
User-Agent: Mutt/1.5.24 (2015-08-30)
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 05 Oct 2017 16:27:37 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 10/03, Jürg Billeter wrote:
>
> My use case is to provide a way for a process to spawn a child and
> ensure that no descendants survive when that child dies.  Avoiding
> runaway processes is desirable in many situations.  My motivation is
> very lightweight (nested) sandboxing (every process is potentially
> sandboxed).
>
> I.e., pid namespaces would be a pretty good fit (assuming they are
> sufficiently lightweight) but CLONE_NEWPID

sorry if this was already discussed, I didn't read this thread yet...

if CLONE_NEWPID is not suitable for any reason. We already have
PR_SET_CHILD_SUBREAPER. Perhaps we can simply add another
PR_SET_KILL_ALL_DESCEDANTS_ON_EXIT? we can use walk_process_tree()
to send SIGKILL.

Oleg.