From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S932800AbcFBUjT (ORCPT <rfc822;w@1wt.eu>);
	Thu, 2 Jun 2016 16:39:19 -0400
Received: from terminus.zytor.com ([198.137.202.10]:42838 "EHLO mail.zytor.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S932171AbcFBUjR (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Thu, 2 Jun 2016 16:39:17 -0400
Subject: Re: [PATCH tty-next] devpts: Make each mount of devpts an independent
 filesystem.
To: "Eric W. Biederman" <ebiederm@xmission.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
References: <CA+55aFyOv3jUOsC-JbfeqM-Rs1z1a+QEt2EejpTf-9EfXdttdg@mail.gmail.com>
 <87oa95gevf.fsf_-_@x220.int.ebiederm.org>
 <CALYGNiOHRrhhdQawRO_XMK98_F9XaEY9ejjxgsC+GnKMn+jQRQ@mail.gmail.com>
 <CA+55aFxKxU89GvfUFahn-LG8vf4OpP069De3qOVaR_un-961gQ@mail.gmail.com>
 <87mvoo8h3d.fsf@x220.int.ebiederm.org>
 <CALYGNiNm4eNo=tMjRwn2sSjydtNeD0ZBT3N0RE1gvUmHmPbSHw@mail.gmail.com>
 <87fuug5i6r.fsf_-_@x220.int.ebiederm.org>
 <874mabt3df.fsf_-_@x220.int.ebiederm.org> <20160506193547.GA30024@kroah.com>
 <572CF43D.2020708@hurleysoftware.com> <20160506195459.GB27790@kroah.com>
 <878tyn4nis.fsf_-_@x220.int.ebiederm.org>
 <CA+55aFwbHVcfHVYrmxHZfwM=K31NL37UcyAOE8ekWKYdcv1Ndw@mail.gmail.com>
 <87porzuys7.fsf@x220.int.ebiederm.org>
Cc: Greg KH <greg@kroah.com>, Peter Hurley <peter@hurleysoftware.com>,
        Andy Lutomirski <luto@amacapital.net>, security@debian.org,
        "security@kernel.org" <security@kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        "security@ubuntu.com >> security" <security@ubuntu.com>,
        Serge Hallyn <serge.hallyn@ubuntu.com>, Willy Tarreau <w@1wt.eu>,
        Aurelien Jarno <aurelien@aurel32.net>,
        One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
        Jann Horn <jann@thejh.net>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jiri Slaby <jslaby@suse.com>, Florian Weimer <fw@deneb.enyo.de>,
        Konstantin Khlebnikov <koct9i@gmail.com>
From: "H. Peter Anvin" <hpa@zytor.com>
Message-ID: <94ee92fa-b07b-af9f-c631-18e96a0a465c@zytor.com>
Date: Thu, 2 Jun 2016 13:36:55 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.1.0
MIME-Version: 1.0
In-Reply-To: <87porzuys7.fsf@x220.int.ebiederm.org>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 06/02/16 13:22, Eric W. Biederman wrote:
> 
> The problem with lookup_one_len_unlocked is that it still calls
> inode_permission.
> 
> As per previous discussions we don't want the path based permission
> checks involved in that lookup.
> 

Is it that we don't *want* it, or that we don't *need* it?  In the
latter case, we could just do whatever makes the code simpler, no?

	-hpa