Re: CAP_SYSLOG, 2.6.38 and user space

[Serge E. Hallyn]

Quoting Serge E. Hallyn (serge@xxxxxxxxxx):
> Quoting david@xxxxxxx (david@xxxxxxx):
> > On Fri, 4 Feb 2011, Serge E. Hallyn wrote:
> > 
> > >Quoting Gergely Nagy (algernon@xxxxxxxxxx):
> > >>On Fri, 2011-02-04 at 16:05 +0000, Serge E. Hallyn wrote:
> > >>>Quoting Serge E. Hallyn (serge@xxxxxxxxxx):
> > >>>>>From 2d7408541dd3a6e19a4265b028233789be6a40f4 Mon Sep 17 00:00:00 2001
> > >>>>From: Serge Hallyn <serge@peq.(none)>
> > >>>>
> > >>>>At 2.6.39 or 2.6.40, let's add a sysctl which defaults to 0.  When
> > >>>>0, refuse if cap_sys_admin, if 1, then allow.  This will allow
> > >>>>users to acknowledge (permanently, if they must, using /etc/sysctl.conf)
> > >>>>that they've seen the syslog message about cap_sys_admin being
> > >>>>deprecated for syslog.
> > >>>>
> > >>>>Signed-off-by: Serge Hallyn <serge@xxxxxxxxxx>
> > >-			goto warn; /* switch to return -EPERM after 2.6.39 */
> > >+		     !capable(CAP_SYSLOG)) {
> > >+			/* remove after 2.6.39 */
> > >+			if (capable(CAP_SYS_ADMIN))
> > >+				WARN_ONCE(1, "Attempt to access syslog with CAP_SYS_ADMIN "
> > >+				  "but no CAP_SYSLOG (deprecated).\n");
> > >+			else
> > >+				return -EPERM;
> > >+		}
> > >	}
> > 
> > why does this need to be removed after 2.6.39?
> > 
> > whenever you go to remove it you will break userspace, what's the
> > benifit of breaking userspace?
> > 
> > I can understand that it's better to have a syslog daemon with
> > CAP_SYSLOG instead of CAP_SYS_ADMIN, but does "it would be better to
> > have userspace changed" really translate into "it's so important to
> > have userspace changed that we need to break any userspace that
> > hasn't changed"?
> > 
> > I really don't think so.
> 
> I think I agree with you.  If someone wants to grant one of the other
> CAP_SYS_ADMIN powers without CAP_SYSLOG, then they can break that into
> yet another, i.e. CAP_IPCSET.  Makes sense.

So if that's how we're leaning, then the following patch is much more
concise.  I'll send this to Linus and any appropriate -stable tomorrow
 if noone objects.