lkml.org 
[lkml]   [2006]   [Dec]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 0/2] file capabilities: two bugfixes

--- "Serge E. Hallyn" <serue@us.ibm.com> wrote:
> Quoting Casey Schaufler (casey@schaufler-ca.com):
> >
> > --- "Serge E. Hallyn" <serue@us.ibm.com> wrote:
> >
> > > ...
> > > The other is that root can lose capabilities by
> > > executing files with
> > > only some capabilities set. The next two
> patches
> > > change these
> > > behaviors.
> >
> > It was the intention of the POSIX group that
> > capabilities be independent of uid. I would
> > argue that the old bevavior was correct, that
> > a program marked to lose a capability ought
> > to even if the uid is 0.
>
> Agreed, and if SECURE_NOROOT is set, that is what
> happens.
> But by default SECURE_NOROOT is not set, in which
> case linux's
> implementation of capabilities behaves differently
> for root.
>
> Without this latest patch, with SECURE_NOROOT not
> set, what was
> actually happening was that the kernel behaved as
> though
> SECURE_NOROOT was not set so long as there was no
> security.capability xattr, and always behaved as
> though
> SECURE_NOROOT was set if there was an xattr. That's
> inconsistent
> and confusing behavior.
>
> The worst part is that root can get around running
> the code
> with limited caps by just copying the file and
> running the
> copy. So it adds no security benefit, and adds an
> inconsistency/complication which could cause
> security risks.

OK, no worries then.


Casey Schaufler
casey@schaufler-ca.com
-
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/

\
 
 \ /
  Last update: 2006-12-08 23:11    [from the cache]
©2003-2011 Jasper Spaans