MIME-Version: 1.0
In-Reply-To: <20120622125551.269552c2.akpm@linux-foundation.org>
References: <20120622192413.GA5774@www.outflux.net>
	<20120622125551.269552c2.akpm@linux-foundation.org>
Date: Fri, 22 Jun 2012 14:09:28 -0700
Message-ID: <CAGXu5jLMRc3svVuPznUkUEcF2HOHRE_6b5bmL-Aiw7FtsN6zHw@mail.gmail.com>
Subject: Re: [PATCH v3] fs: introduce pipe-only dump mode suid_dumpable=3
From: Kees Cook <keescook@chromium.org>
To: Andrew Morton <akpm@linux-foundation.org>
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
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 8BIT
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 990
Lines: 28

On Fri, Jun 22, 2012 at 12:55 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Fri, 22 Jun 2012 12:24:13 -0700
> Kees Cook <keescook@chromium.org> wrote:
>
>> The value
>> of suid_dumpable=2 is now historic, and attempting to set this sysctl
>> value returns -EINVAL.
>
> This sounds a bit harsh - will it not cause existing configurations to
> immediately break? ?If so, would it not be better to retain the =2 mode
> for a while, and emit a nice warning when it is set?

I view it as a security vulnerability, so I'd rather see it
eliminated. I see "=1" as a security vulnerability too, but at least
that's well-known to be a bad idea. The "=2" mode has been assumed to
be safe, but it isn't.

-Kees

-- 
Kees Cook
Chrome OS Security
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/