linux-kernel - Re: [RESEND PATCH] prctl: add PR_[GS]ET_PDEATHSIG

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Message-ID: <20171005162733.GA20068@redhat.com>
Date:   Thu, 5 Oct 2017 18:27:33 +0200
From:   Oleg Nesterov <oleg@...hat.com>
To:     Jürg Billeter <j@...ron.ch>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Filipe Brandenburger <filbranden@...gle.com>,
        David Wilcox <davidvsthegiant@...il.com>, hansecke@...il.com,
        linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH] prctl: add PR_[GS]ET_PDEATHSIG_PROC

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.