From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756567Ab1JQWjk (ORCPT ); Mon, 17 Oct 2011 18:39:40 -0400 Received: from mail-gy0-f174.google.com ([209.85.160.174]:63683 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754492Ab1JQWjj (ORCPT ); Mon, 17 Oct 2011 18:39:39 -0400 Date: Mon, 17 Oct 2011 15:39:36 -0700 From: Andrew Morton To: Dan Ballard Cc: Randy Dunlap , Ingo Molnar , Lennart Poettering , Kay Sievers , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] kernel/sysctl.c: Add cap_last_cap to /proc/sys/kernel Message-Id: <20111017153936.c47a27ff.akpm@linux-foundation.org> In-Reply-To: <1318690205-2731-1-git-send-email-dan@mindstab.net> References: <1318460194-31983-1-git-send-email-dan@mindstab.net> <1318690205-2731-1-git-send-email-dan@mindstab.net> X-Mailer: Sylpheed 3.0.2 (GTK+ 2.20.1; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 15 Oct 2011 07:50:05 -0700 Dan Ballard wrote: > Userspace needs to know the highest valid capability of the running > kernel, which right now cannot reliably be retrieved from the header > files only. The fact that this value cannot be determined properly > right now creates various problems for libraries compiled on newer > header files which are run on older kernels. They assume > capabilities are available which actually aren't. Specfically, what libraries are we talking about here? > Now the capability is exported in /proc/sys/kernel/cap_last_cap. Ever the optimist: is there any way in which we can avoid 0444 permissions on this?