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

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Message-Id: <20171002162041.a7cefe8af71327b8becd2347@linux-foundation.org>
Date:   Mon, 2 Oct 2017 16:20:41 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Jürg Billeter <j@...ron.ch>
Cc:     Oleg Nesterov <oleg@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Eric Biederman <ebiederm@...ssion.com>,
        Michael Kerrisk <mtk.manpages@...il.com>,
        Filipe Brandenburger <filbranden@...gle.com>,
        David Wilcox <davidvsthegiant@...il.com>,
        "Adam H . Peterson" <alphaetapi@...mail.com>, hansecke@...il.com,
        linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH] prctl: add PR_[GS]ET_PDEATHSIG_PROC

On Fri, 29 Sep 2017 14:30:58 +0200 Jürg Billeter <j@...ron.ch> wrote:

> PR_SET_PDEATHSIG sets a parent death signal that the calling process
> will get when its parent thread dies, even when the result of getppid()
> doesn't change because the calling process is reparented to a different
> thread in the same parent process. When managing multiple processes, a
> process-based parent death signal is much more useful. E.g., to avoid
> stray child processes.
> 
> PR_SET_PDEATHSIG_PROC sets a process-based death signal. Unlike
> PR_SET_PDEATHSIG, this is inherited across fork to allow killing a whole
> subtree without race conditions.
> 
> This can be used for sandboxing when combined with a seccomp filter.
> 
> There have been previous attempts to support this by changing the
> behavior of PR_SET_PDEATHSIG. However, that would break existing
> applications. See https://marc.info/?l=linux-kernel&m=117621804801689
> and https://bugzilla.kernel.org/show_bug.cgi?id=43300

Are Eric and Oleg OK with this?

A prctl manpage update will be needed, please (cc linux-api).