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Date:   Sat, 30 Mar 2019 17:37:51 +0100
From:   Christian Brauner <christian@brauner.io>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Jann Horn <jannh@google.com>, Andrew Lutomirski <luto@kernel.org>,
        David Howells <dhowells@redhat.com>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        Linux API <linux-api@vger.kernel.org>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
        Kees Cook <keescook@chromium.org>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Michael Kerrisk-manpages <mtk.manpages@gmail.com>,
        Jonathan Kowalski <bl0pbl33p@gmail.com>,
        "Dmitry V. Levin" <ldv@altlinux.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>,
        Nagarathnam Muthusamy <nagarathnam.muthusamy@oracle.com>,
        Aleksa Sarai <cyphar@cyphar.com>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Joel Fernandes <joel@joelfernandes.org>,
        Daniel Colascione <dancol@google.com>
Subject: Re: [PATCH v2 0/5] pid: add pidfd_open()
Message-ID: <20190330163750.xrrqmcyfd2mchamf@brauner.io>
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On Sat, Mar 30, 2019 at 09:24:23AM -0700, Linus Torvalds wrote:
> On Sat, Mar 30, 2019 at 9:19 AM Christian Brauner <christian@brauner.io> wrote:
> >
> > From pure API perspective that's all I care about: independence of procfs.
> > Once we have pidfd_open() we can cleanly signal threads etc.
> 
> But "independence from procfs" means that you damn well don't then do
> "oh, now I have a pidfd, I want to turn it into a /proc fd and then
> munge around there".
> 
> So I'm literally saying that it had better really *be* independent
> from /proc. It is the standalone version, but it's most definitely
> also the version that doesn't then give you secret access to /proc.
> 
> And it weorries me a lot that people are trying to play these kinds of
> games. I'm just seeing some android patch that adds this horror and
> then starts using it.

The original need for this conversion thing came from Android indeed. I
won't go forward with any such patches. 

Christian