Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758053AbcLPVFj (ORCPT ); Fri, 16 Dec 2016 16:05:39 -0500 Received: from h2.hallyn.com ([78.46.35.8]:46588 "EHLO h2.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754105AbcLPVFa (ORCPT ); Fri, 16 Dec 2016 16:05:30 -0500 Date: Fri, 16 Dec 2016 15:05:39 -0600 From: "Serge E. Hallyn" To: John Stultz Cc: "Serge E. Hallyn" , "Michael Kerrisk (man-pages)" , Casey Schaufler , James Morris , Kees Cook , Andy Lutomirski , Jann Horn , "Eric W. Biederman" , linux-man , linux-security-module , lkml , "Rafael J. Wysocki" Subject: Re: RFC: capabilities(7): notes for kernel developers Message-ID: <20161216210539.GA15589@mail.hallyn.com> References: <43dcc6dc-265b-5eaf-3a70-701e05200b9f@gmail.com> <9ed6371f-3d38-45b1-a85b-1fbb3e5b4fc7@schaufler-ca.com> <7a6b5f38-de8e-d8d4-e6f7-feae3f8d192e@schaufler-ca.com> <20161216201026.GB14856@mail.hallyn.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2891 Lines: 66 Quoting John Stultz (john.stultz@linaro.org): > On Fri, Dec 16, 2016 at 12:10 PM, Serge E. Hallyn wrote: > > Quoting Michael Kerrisk (man-pages) (mtk.manpages@gmail.com): > >> On 12/16/2016 01:44 AM, Casey Schaufler wrote: > >> > On 12/15/2016 4:31 PM, John Stultz wrote: > >> >> On Thu, Dec 15, 2016 at 12:40 PM, Casey Schaufler > >> >> wrote: > >> >>> On 12/15/2016 11:41 AM, Michael Kerrisk (man-pages) wrote: > >> >>>> On 12/15/2016 05:29 PM, Casey Schaufler wrote: > >> >>>>> CAP_WAKE_ALARM could readily be CAP_TIME. > >> >>>> Actually, I don't quite understand what you mean with that sentence. > >> >>>> Could you elaborate? > >> >>> Should have said CAP_SYS_TIME > >> >>> > >> >>> Setting an alarm could be considered a time management function, > >> >>> depending on what it actually does. > >> >> Just a nit here. CAP_WAKE_ALARM is more about the privilege of waking > >> >> a system from suspend, while CAP_SYS_TIME covers the ability to set > >> >> the time. One wouldn't necessarily want to give applications which > >> >> could wake a system up the capability to also set the time. > >> > > >> > Doesn't really matter, except that an ignorant developer > >> > might make the mistake I did and assume that WAKE_ALARM > >> > was somehow related to time management. If you want to use > >> > it as an example don't let my dunderheadedness get in your > >> > way. > >> > >> Actually, I decided it wasn't such a good example anyway. > >> That capability could potentially be generic. (But it probably > >> should better have been named something like 'CAP_WAKE_SYSTEM'.) > > > > How about: > > > > Subject: [PATCH 1/1] capabilities: alias CAP_WAKE_SYSTEM to CAP_WAKE_ALARM > > > > As suggested by Michael Kerrisk his is a less confusing name, and > > this won't break any old userspace. > > > > Signed-off-by: Serge Hallyn > > Cc: Michael Kerrisk > > --- > > include/uapi/linux/capability.h | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h > > index fd4f87d..ba972ff 100644 > > --- a/include/uapi/linux/capability.h > > +++ b/include/uapi/linux/capability.h > > @@ -357,6 +357,8 @@ struct vfs_ns_cap_data { > > > > #define CAP_WAKE_ALARM 35 > > > > +#define CAP_WAKE_SYSTEM CAP_WAKE_ALARM > > + > > I was thinking of the same thing. Although I might rename the > numerical define to WAKE_SYSTEM and put WAKE_ALARM as the alias (along > with a comment as to WAKE_ALARM being deprecated), so its more clear > which is the one that ought to be used by new code. > > However, in the spirit of this thread, we might even consider > broadening the cap silo a bit further, to something like > CAP_WAKE_SUSPEND, such that it might also be able to cover broader PM > actions? Or just CAP_UNSUSPEND?