Re: [cifs-utils PATCH] cifs.upcall: trim even more capabilities

[Jeff Layton <jlayton-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>]

On Thu, 2017-02-16 at 09:28 -0800, Pavel Shilovsky wrote:
> 2017-02-16 6:59 GMT-08:00 Jeff Layton <jlayton-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>:
> > We really only need CAP_DAC_READ_SEARCH, not CAP_DAC_OVERRIDE, and
> > only when we are going to probe the environ file.
> > 
> > Also, fix the non-libcap-ng trim_capabilities prototype.
> > 
> > Signed-off-by: Jeff Layton <jlayton-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>
> > ---
> >  cifs.upcall.c | 17 ++++++++---------
> >  1 file changed, 8 insertions(+), 9 deletions(-)
> > 
> > diff --git a/cifs.upcall.c b/cifs.upcall.c
> > index 6d9c427b7032..dae58b919408 100644
> > --- a/cifs.upcall.c
> > +++ b/cifs.upcall.c
> > @@ -70,22 +70,21 @@ typedef enum _sectype {
> > 
> >  #ifdef HAVE_LIBCAP_NG
> >  static int
> > -trim_capabilities(bool need_ptrace)
> > +trim_capabilities(bool need_environ)
> >  {
> >         capng_clear(CAPNG_SELECT_BOTH);
> > 
> > -       /*
> > -        * Need PTRACE and DAC_OVERRIDE for environment scraping, SETGID to
> > -        * change gid and grouplist, and SETUID to change uid.
> > -        */
> > +       /* SETUID and SETGID to change uid, gid, and grouplist */
> >         if (capng_updatev(CAPNG_ADD, CAPNG_PERMITTED|CAPNG_EFFECTIVE,
> > -                       CAP_SETUID, CAP_SETGID, CAP_DAC_OVERRIDE, -1)) {
> > +                       CAP_SETUID, CAP_SETGID, -1)) {
> >                 syslog(LOG_ERR, "%s: Unable to update capability set: %m\n", __func__);
> >                 return 1;
> >         }
> > 
> > -       if (need_ptrace &&
> > -           capng_update(CAPNG_ADD, CAPNG_PERMITTED|CAPNG_EFFECTIVE, CAP_SYS_PTRACE)) {
> > +        /* Need PTRACE and DAC_OVERRIDE for environment scraping */
> 
> It seems that the comment above doesn't reflect the proposed change.
> Should it be DAC_READ_SEARCH instead?
> 

Yes! It should and it's fixed in the version in the tree.

Thanks,
-- 
Jeff Layton <jlayton-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>