[Nicolas.Williams@ubsw.com: Re: Interposing LSA functions (was: RE: [pamldap] PAM for Windows NT/2000)]

[Luke Kenneth Casson Leighton <lk...@samba-tng.org>]

----- Forwarded message from Nicolas Williams <Ni...@ubsw.com> -----

Delivered-To: lkcl@angua.rince.de
Date: Wed, 29 Aug 2001 10:26:47 -0400
From: Nicolas Williams <Ni...@ubsw.com>
To: Luke Kenneth Casson Leighton <lk...@samba-tng.org>,
	Luke Howard <lu...@padl.com>
Cc: jalbertop@aranea.com.mx, norbert.klasen@daasi.de,
	pamldap@padl.com
Subject: Re: Interposing LSA functions (was: RE: [pamldap] PAM for Windows NT/2000)
X-Mailer: Mutt 0.93.2i
In-Reply-To: <20...@angua.rince.de>; from Luke Kenneth Casson Leighton on Wed, Aug 29, 2001 at 04:10:34PM +0200
X-WDR-Disclaimer: Version $Revision: 1.13 $

On Wed, Aug 29, 2001 at 04:10:34PM +0200, Luke Kenneth Casson Leighton wrote:
> On Wed, Aug 29, 2001 at 08:45:39PM +1000, Luke Howard wrote:
> > 
> > The URL:
> > 
> > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/security/hh/secpack/customsecfunctions_9js1.asp
> > 
> > is worth a look as it describes the API used to retrieve the
> > authorization data for a user and create an LSA security token
> > from that data. 
> > 
> 
> interesting.  so it might be possible to write
> a setuid() for nt and for cygwin, after all.

It exists, in a way, you just have to have the client's AP-REQ!

Actually, here's how it works:

 - if you're a system service (a daemon running as root) you can become
   (impersonate) any local user

 - if you're any kind of service, even non-priviledged, you can become
   (impersonate) any domain user who authenticates to you using GSS-API
   (SSPI). This works because:

    - a) the service passes the GSS tokens to the LSA,

    which

    - b) validates the tokens (and produces tokens) using any secret
         keys (which the service need not have access to)

   and

    - c) obtains the client's profile which the LSA then uses to provide
         a handle to the service which the service can then use to
	 *locally* impersonate the client

You can't adapt that to the setuid() model -- that's because the setuid
model sucks. Firstly because the UIDs are a flat namespace (so no domain
users) and secondly because the above model does not fit.

I'd rather adapt the win2k model to Unix.

> i'm cc'ing this to apr dev: someone there might
> be interested in investigating and completing the
> apr user-related functions.
>
> luke


Cheers,

Nico
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