Re: What to do about nologin(8)?

On Mon, 2004-02-23 at 20:16, John Baldwin wrote:
> On Monday 23 February 2004 02:58 pm, Doug Rabson wrote:
> > On Mon, 2004-02-23 at 17:45, Colin Percival wrote:
> > >    As anyone who reads cvs-all (or Mark Johnston's wonderful
> > > summaries thereof) will know, I recently added logging into
> > > nologin(8): Instead of simply printing an error message, it
> > > now (via syslog) records the refused login attempt.
> > >    For security reasons, nologin(8) must be statically linked;
> > > as a result, adding logging has increased the binary size by
> > > slightly over 100K (on i386).  For historical reasons (which
> > > is to say, "nobody seems to know why"), nologin is located in
> > > /sbin, which means that this has a non-trivial effect upon
> > > the space used on the root partition.  Some people are unhappy
> > > about this.
> > >    I can see a number of possible options; I'd like to hear
> > > opinions on which would be the best.
> >
> > How about:
> >
> > 7: Use 'system("logger ...") to log the failed login?
> 
> Wouldn't that be subject to the same LD_LIBRARY_PATH concerns since logger is 
> dynamically linked and you could trojan it's libc?

Yes, but nologin will have the chance to sanitize its environment before
running it.