From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=jaku=4I=lists.openwall.com=kernel-hardening-return-17872-kernel-hardening=archiver.kernel.org@kernel.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
X-Spam-Level: 
X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no
	version=3.4.0
Received: from mail.kernel.org (mail.kernel.org [198.145.29.99])
	by smtp.lore.kernel.org (Postfix) with ESMTP id 0EB39C11D00
	for <kernel-hardening@archiver.kernel.org>; Thu, 20 Feb 2020 23:08:22 +0000 (UTC)
Received: from mother.openwall.net (mother.openwall.net [195.42.179.200])
	by mail.kernel.org (Postfix) with SMTP id 66117222C4
	for <kernel-hardening@archiver.kernel.org>; Thu, 20 Feb 2020 23:08:21 +0000 (UTC)
DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 66117222C4
Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk
Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17872-kernel-hardening=archiver.kernel.org@lists.openwall.com
Received: (qmail 26307 invoked by uid 550); 20 Feb 2020 23:08:16 -0000
Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm
Precedence: bulk
List-Post: <mailto:kernel-hardening@lists.openwall.com>
List-Help: <mailto:kernel-hardening-help@lists.openwall.com>
List-Unsubscribe: <mailto:kernel-hardening-unsubscribe@lists.openwall.com>
List-Subscribe: <mailto:kernel-hardening-subscribe@lists.openwall.com>
List-ID: <kernel-hardening.lists.openwall.com>
Received: (qmail 26266 invoked from network); 20 Feb 2020 23:08:15 -0000
Date: Thu, 20 Feb 2020 23:07:58 +0000
From: Al Viro <viro@zeniv.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	Linux API <linux-api@vger.kernel.org>,
	Linux FS Devel <linux-fsdevel@vger.kernel.org>,
	Linux Security Module <linux-security-module@vger.kernel.org>,
	Akinobu Mita <akinobu.mita@gmail.com>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>,
	Daniel Micay <danielmicay@gmail.com>,
	Djalal Harouni <tixxdz@gmail.com>,
	"Dmitry V . Levin" <ldv@altlinux.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	"J . Bruce Fields" <bfields@fieldses.org>,
	Jeff Layton <jlayton@poochiereds.net>,
	Jonathan Corbet <corbet@lwn.net>, Kees Cook <keescook@chromium.org>,
	Oleg Nesterov <oleg@redhat.com>,
	Solar Designer <solar@openwall.com>
Subject: Re: [PATCH 0/7] proc: Dentry flushing without proc_mnt
Message-ID: <20200220230758.GT23230@ZenIV.linux.org.uk>
References: <20200212200335.GO23230@ZenIV.linux.org.uk>
 <CAHk-=wi+1CPShMFvJNPfnrJ8DD8uVKUOQ5TQzQUNGLUkeoahkg@mail.gmail.com>
 <20200212203833.GQ23230@ZenIV.linux.org.uk>
 <20200212204124.GR23230@ZenIV.linux.org.uk>
 <CAHk-=wi5FOGV_3tALK3n6E2fK3Oa_yCYkYQtCSaXLSEm2DUCKg@mail.gmail.com>
 <87lfp7h422.fsf@x220.int.ebiederm.org>
 <CAHk-=wgmn9Qds0VznyphouSZW6e42GWDT5H1dpZg8pyGDGN+=w@mail.gmail.com>
 <87pnejf6fz.fsf@x220.int.ebiederm.org>
 <871rqpaswu.fsf_-_@x220.int.ebiederm.org>
 <CAHk-=whX7UmXgCKPPvjyQFqBiKw-Zsgj22_rH8epDPoWswAnLA@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <CAHk-=whX7UmXgCKPPvjyQFqBiKw-Zsgj22_rH8epDPoWswAnLA@mail.gmail.com>
Sender: Al Viro <viro@ftp.linux.org.uk>

On Thu, Feb 20, 2020 at 03:02:22PM -0800, Linus Torvalds wrote:
> On Thu, Feb 20, 2020 at 12:48 PM Eric W. Biederman
> <ebiederm@xmission.com> wrote:
> >
> > Linus, does this approach look like something you can stand?
> 
> A couple of worries, although one of them seem to have already been
> resolved by Al.
> 
> I think the real gatekeeper should be Al in general.  But other than
> the small comments I had, I think this might work just fine.
> 
> Al?

I'll need to finish RTFS there; I have initially misread that patch,
actually - Eric _is_ using that thing both for those directories
and for sysctl inodes.  And the prototype for that machinery (the
one he'd pulled from proc_sysctl.c) is playing with pinning superblocks
way too much; for per-pid directories that's not an issue, but
for sysctl table removal you are very likely to hit a bunch of
evictees on the same superblock...