From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v3] fs: introduce pipe-only dump mode suid_dumpable=3
Date: Fri, 22 Jun 2012 15:20:29 -0700
Message-ID: <20120622152029.638ade70.akpm@linux-foundation.org>
References: <20120622192413.GA5774@www.outflux.net>
	<20120622125551.269552c2.akpm@linux-foundation.org>
	<CAGXu5jLMRc3svVuPznUkUEcF2HOHRE_6b5bmL-Aiw7FtsN6zHw@mail.gmail.com>
	<20120622143435.c1ba744e.akpm@linux-foundation.org>
	<CAGXu5jJq-hZ4Q-ThdQ+KD=uGgHq1KP0_tTsefG8qkFGi8Em-qw@mail.gmail.com>
	<20120622145711.d7f720cd.akpm@linux-foundation.org>
	<CAGXu5jLOJrZTNKh=G75wP2fo-cPj_mM-Urc+4hDVvyJpiy+7Dg@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Cc: linux-kernel@vger.kernel.org, Alan Cox <alan@linux.intel.com>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Rob Landley <rob@landley.net>, Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Doug Ledford <dledford@redhat.com>,
	Marcel Holtmann <marcel@holtmann.org>,
	Serge Hallyn <serge.hallyn@canonical.com>,
	Joe Korty <joe.korty@ccur.com>,
	David Howells <dhowells@redhat.com>,
	James Morris <james.l.morris@oracle.com>,
	linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org
To: Kees Cook <keescook@chromium.org>
Return-path: <linux-doc-owner@vger.kernel.org>
In-Reply-To: <CAGXu5jLOJrZTNKh=G75wP2fo-cPj_mM-Urc+4hDVvyJpiy+7Dg@mail.gmail.com>
Sender: linux-doc-owner@vger.kernel.org
List-Id: linux-fsdevel.vger.kernel.org

On Fri, 22 Jun 2012 15:07:45 -0700
Kees Cook <keescook@chromium.org> wrote:

> mode=2 to disk _should_ break, is my point.

And my point is that we should at least tell people that we broke it. 
I don't believe that returning an EINVAL from the write() is
sufficient.  Because it introduces a high risk that people will run
misconfigured systems for lengthy periods and it will cause them to
have to do a *lot* of work once they discover that their system is
misbehaving.

So if we really really must instabreak back-compatibility, we should
shout loudly into syslog about it: tell people that their system is
broken and tell them what to do about it.

And we should explain and justify this extraordinary action in the
patch changelog.