Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 19 Nov 2018 19:20:43 +0100
From:   Christian Brauner <christian@brauner.io>
To:     Andy Lutomirski <luto@kernel.org>
Cc:     "Eric W. Biederman" <ebiederm@xmission.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "Serge E. 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>,
        Daniel Colascione <dancol@google.com>,
        Tim Murray <timmurray@google.com>,
        linux-man <linux-man@vger.kernel.org>,
        Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH v1 1/2] proc: get process file descriptor from /proc/<pid>
Message-ID: <20181119182038.27obrbpxp54rhfxt@brauner.io>
References: <20181119103241.5229-1-christian@brauner.io>
 <20181119103241.5229-2-christian@brauner.io>
 <CALCETrVvHu2dSJs1dpA-2ozGhZGxbGrnYbUuh98rkCdsz42rfg@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <CALCETrVvHu2dSJs1dpA-2ozGhZGxbGrnYbUuh98rkCdsz42rfg@mail.gmail.com>
User-Agent: NeoMutt/20180716
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Nov 19, 2018 at 07:32:33AM -0800, Andy Lutomirski wrote:
> On Mon, Nov 19, 2018 at 2:33 AM Christian Brauner <christian@brauner.io> wrote:
> >
> > With this patch an open() call on /proc/<pid> will give userspace a handle
> > to struct pid of the process associated with /proc/<pid>. This allows to
> > maintain a stable handle on a process.
> > I have been discussing various approaches extensively during technical
> > conferences this year culminating in a long argument with Eric at Linux
> > Plumbers. The general consensus was that having a handle on a process
> > should be something that is very simple and easy to maintain with the
> > option of being extensible via a more advanced api if the need arises. I
> > believe that this patch is the most simple, dumb, and therefore
> > maintainable solution.
> 
> How does the mechanism you're adding here differ from proc_pid()?

I'm sorry, I am missing the context around proc_pid()?. Are you talking
about the the proc_pid() function in "internal.h"? What exactly is the
proc_pid() mechanism?