linux-kernel - Re: [PATCH] proc: allow killing processes via file descriptors

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Message-ID: <CAKOZueu78Urbc-Vt--ZntGAG_i-LrNsPjGmRi7F8zuTUQ=iHug@mail.gmail.com>
Date:   Mon, 19 Nov 2018 08:27:57 -0800
From:   Daniel Colascione <dancol@...gle.com>
To:     Dmitry Safonov <0x7f454c46@...il.com>
Cc:     Andy Lutomirski <luto@...nel.org>,
        Randy Dunlap <rdunlap@...radead.org>,
        Christian Brauner <christian@...uner.io>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        open list <linux-kernel@...r.kernel.org>,
        Serge Hallyn <serge@...lyn.com>, Jann Horn <jannh@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Oleg Nesterov <oleg@...hat.com>,
        Aleksa Sarai <cyphar@...har.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>,
        Linux API <linux-api@...r.kernel.org>,
        Tim Murray <timmurray@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Jan Engelhardt <jengelh@...i.de>,
        Andrei Vagin <avagin@...il.com>
Subject: Re: [PATCH] proc: allow killing processes via file descriptors

On Mon, Nov 19, 2018 at 8:13 AM, Dmitry Safonov <0x7f454c46@...il.com> wrote:
> I wonder how fast it would be holding a pid with another open()ed fd.
> And then you need to read comm (or how you filter whom to kill).
> It seems to me that procfs will be even slower with this safe-way.
> But I might misunderstand the idea, excuses.
>
> So, I just wanted to gently remind about procfs with netlink socket[1].

We discussed netlink was extensively on the thread about
/proc/pid/kill. For numerous reasons, it's not suitable for
fundamental process management. We really need an FD-based interface
to processes, just like we have FD-based interfaces to other resource
types. We need something consistent and reliable, not an abuse of a
monitoring interface.

> Probably, if it's time to add a new API for procfs, netlink may be more
> desirable.

Definitely not.