PAM based filter

[DC <dc dcarr org>]

I've tried this but was unsucessful.  Have a look at this:

/* pam_permit module */

/*
* $Id: pam_permit.c,v 1.2 2000/12/04 19:02:34 baggins Exp $
*
* Written by Andrew Morgan <morgan parc power net> 1996/3/11
*
*/

#define DEFAULT_USER "david"

#include <stdio.h>

/*
* here, we make definitions for the externally accessible functions
* in this file (these definitions are required for static modules
* but strongly encouraged generally) they are used to instruct the
* modules include file to define their prototypes.
*/

#define PAM_SM_AUTH
#define PAM_SM_ACCOUNT
#define PAM_SM_SESSION
#define PAM_SM_PASSWORD

#include <security/pam_modules.h>
#include <security/_pam_macros.h>

/* --- authentication management functions --- */

PAM_EXTERN
int pam_sm_authenticate(pam_handle_t *pamh,int flags,int argc
                       ,const char **argv)
{
   int retval;
   const char *user=NULL;

   /*
    * authentication requires we know who the user wants to be
    */
   /*retval = pam_get_user(pamh, &user, NULL);
   if (retval != PAM_SUCCESS) {
       D(("get user returned error: %s", pam_strerror(pamh,retval)));
       return retval;
   }
   if (user == NULL || *user == '\0') {

   D(("username not known"));
   pam_set_item(pamh, PAM_USER, (const void *) DEFAULT_USER);

   //}
   //user = NULL; */                                           /* clean 
up */

     D(("username not known"));
     pam_set_item(pamh, PAM_USER, (const void *) DEFAULT_USER);

   return PAM_SUCCESS;
}

PAM_EXTERN
int pam_sm_setcred(pam_handle_t *pamh,int flags,int argc
                  ,const char **argv)
{
 D(("username not known"));
 pam_set_item(pamh, PAM_USER, (const void *) DEFAULT_USER);
 
 return PAM_SUCCESS;
}

/* --- account management functions --- */

PAM_EXTERN
int pam_sm_acct_mgmt(pam_handle_t *pamh,int flags,int argc
                    ,const char **argv)
{
 D(("username not known"));
 pam_set_item(pamh, PAM_USER, (const void *) DEFAULT_USER);
 
 return PAM_SUCCESS;
}

/* --- password management --- */

PAM_EXTERN
int pam_sm_chauthtok(pam_handle_t *pamh,int flags,int argc
                    ,const char **argv)
{
 D(("username not known"));
 pam_set_item(pamh, PAM_USER, (const void *) DEFAULT_USER);
 return PAM_SUCCESS;
}

/* --- session management --- */

PAM_EXTERN
int pam_sm_open_session(pam_handle_t *pamh,int flags,int argc
                       ,const char **argv)
{
 D(("username not known"));
 pam_set_item(pamh, PAM_USER, (const void *) DEFAULT_USER);
 return PAM_SUCCESS;
}

PAM_EXTERN
int pam_sm_close_session(pam_handle_t *pamh,int flags,int argc
                        ,const char **argv)
{
    return PAM_SUCCESS;
}

/* end of module definition */

#ifdef PAM_STATIC

/* static module data */

struct pam_module _pam_permit_modstruct = {
   "pam_chuser",
   pam_sm_authenticate,
   pam_sm_setcred,
   pam_sm_acct_mgmt,
   pam_sm_open_session,
   pam_sm_close_session,
   pam_sm_chauthtok
};

#endif

and my gdm pam config
#%PAM-1.0
auth       required     pam_env.so
auth       required     pam_chuser.so
auth       required     pam_stack.so service=system-auth
auth       required     pam_nologin.so
account    required     pam_chuser.so
account    required     pam_stack.so service=system-auth
password   required     pam_chuser.so
password   required     pam_stack.so service=system-auth
session    required     pam_chuser.so
#session    required    pam_stack.so service=system-auth
session    optional     pam_console.so

Thanks for your time,
-David Carr