Am Montag, 3. Mai 2010 23:16:46 schrieb Sumit Bose:
> On Mon, May 03, 2010 at 10:51:10PM +0200, Oliver Burtchen wrote:
> > Am Montag, 3. Mai 2010 21:17:35 schrieb Dmitri Pal:
> > > Stephen Gallagher wrote:
> > > > On 05/03/2010 02:55 PM, Rob Crittenden wrote:
> > > >> Oliver Burtchen wrote:
> > > >>> What are the exact service-names to use in --service? I know
> > > >>> basically they are the ones like in /etc/services, or what pam
> > > >>> uses. But I noticed that both ssh and sshd are applicable for ssh.
> > > >>> Is there somewhere a list or do they provide it by their selfs, and
> > > >>> I can only make a good guess and try.
> > > >>
> > > >> To be honest, I'm not sure myself. I'm guessing that sssd has a
> > > >> mechanism for determining this. I've filed
> > > >> https://bugzilla.redhat.com/show_bug.cgi?id=588412 to track this
> > > >> question.
> > > >
> > > > I'm going to let Sumit comment on the Bugzilla ticket, since he'd
> > > > know better, but I'm 99% certain that we get this directly from PAM
> > > > (as in, the application itself provides that data when making a PAM
> > > > request).
> > > >
> > > > Looking at a recent auth I performed on my system, I see the raw PAM
> > > > data that comes in from (for example) 'su -l' is reported to us as
> > > > "service: su-l".
> > > >
> > > > My assumption is that SSSD's HBAC simply treats that as canonical.
> > >
> > > Thanks for reminding me. It now rings the bell. The service name is
> > > what application provides when uses pam calls. There is no full
> > > enumeration. It is whatever is used by an application.
> > > Having a good list would be nice though, at least identifying the
> > > applications that we already know use specific service names.
> >
> > For the record: After reading Sumits reply at bugzilla and this
> >
> > "In general, the service name is the name of the program used to access
> > the service, not the program used to provide the service. This is why the
> > service wu-ftpd, defines its service name as /etc/pam.d/ftp." quoted from
> >
> > http://www.redhat.com/docs/manuals/linux/RHL-8.0-Manual/ref-guide/s1-pam-
> > config-files.html
> >
> > I tested it a little bit out:
> >
> > If you set a hbac-rule with --service=su-l, it will only apply to "su -l"
> > or "su -", but not to a simple "su".
> >
> > If you set a hbac-rule with --service=su, it will apply to "su -l", "su
> > -"and a simple "su".
> >
> > So my assumption is, that applications do try from a specific name, down
> > to the general one. This is why "sshd" and "ssh" work. Or is it pam who
> > does this magic?
> 
> No it is not PAM, but some kind of error on my side. The strings sssd gets
> from the LDAP server are not terminated with \0, but the size is known
> (this is because the ASN.1 coding of the LDAP messages). I was lazy and
> just compared up to the length return by LDAP. Although the effect might
> look convenient I think this is an error. I'll try to fix it tomorrow.

Yes, at first sight it looked convenient. But arghh, currently a hbac-rule for 
"su" also matches "sudo"? Well, good to nailed it down.  ;-)   I'll appreciate 
your corrections.

But despite that it would be very nice to have some way to set a rule for a 
"category" or group of services. It is very error-prone to administer the same 
set of rules for example for ssh, su, login seperately. I can think of 
different approaches to achieve that, but don't know what's best.

Maybe it should be possible to collect services in a group. Then the frontend 
(cli or webui) could apply modifications to all members of this named group, if 
asked so?

Best regards,
Oli


> 
> bye,
> Sumit
> 
> > Btw: I also think a good list with well known services would be nice, so
> > someone who tries to set up wu-ftpd, like the example in the redhat-docu,
> > uses "ftp", and not "wu-ftpd". It's just a wish for the upcomming
> > documentation. ;-)
> >
> > Best regards,
> > Oli
> 
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-- 
Oliver Burtchen, Berlin

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