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From:   Daniel Colascione <dancol@google.com>
Date:   Mon, 19 Nov 2018 08:27:57 -0800
Message-ID: <CAKOZueu78Urbc-Vt--ZntGAG_i-LrNsPjGmRi7F8zuTUQ=iHug@mail.gmail.com>
Subject: Re: [PATCH] proc: allow killing processes via file descriptors
To:     Dmitry Safonov <0x7f454c46@gmail.com>
Cc:     Andy Lutomirski <luto@kernel.org>,
        Randy Dunlap <rdunlap@infradead.org>,
        Christian Brauner <christian@brauner.io>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        open list <linux-kernel@vger.kernel.org>,
        Serge Hallyn <serge@hallyn.com>, Jann Horn <jannh@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>,
        Aleksa Sarai <cyphar@cyphar.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Linux FS Devel <linux-fsdevel@vger.kernel.org>,
        Linux API <linux-api@vger.kernel.org>,
        Tim Murray <timmurray@google.com>,
        Kees Cook <keescook@chromium.org>,
        Jan Engelhardt <jengelh@inai.de>,
        Andrei Vagin <avagin@gmail.com>
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On Mon, Nov 19, 2018 at 8:13 AM, Dmitry Safonov <0x7f454c46@gmail.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.