Re: [PATCH] Trace event for capable().

["Serge E. Hallyn" <serge@hallyn.com>]

Quoting Serge Hallyn (serge@hallyn.com):
> 
> ----- Original message -----
> > On Fri, May 18, 2012 at 3:33 PM, richard -rw- weinberger
> > <richard.weinberger@gmail.com> wrote:
> > > 
> > > On Thu, May 17, 2012 at 9:50 PM, Auke Kok <auke-jan.h.kok@intel.com>
> > > wrote:
> > > > Add a simple trace event for capable().
> > > > 
> > > > There's been a lot of discussion around capable(), and there
> > > > are plenty of tools to help reduce capabilities' usage from
> > > > userspace. A major gap however is that it's almost impossible
> > > > to see or verify which bits are requested from either userspace
> > > > or in the kernel.
> > > > 
> > > > This patch adds a minimal tracer that will print out which
> > > > CAPs are requested and whether the request was granted.
> > > 
> > > Can we please have support for user namespaces?
> > > At least idicate whether the current namespace is init_user_ns or not.
> > 
> > that was the main reason for sending this out already - that should be
> > trivial to add to the trace event, but I haven't looked at namespaces
> > yet myself. I'll check it out.
> > 
> 
> right, trivial to add, but either go through linux-next or wait for Eric's
> patchset to move from there to Linus' tree.  Print the
> from_kuid(&init_user_ns, current_uid()), and if not in init_user_ns then also
> print the ns creator and task uid in his own ns.
> 
> I don't think you need to do that right now.

Oh, you'll also need to add the uid (in init_user_ns) of the owner of
the target namespace ('ns').  Otherwise, the admin may freak out seeing
uid 500 got cap_sys_admin :)

-serge