pam_get_item() problems

[Jason DiCioccio]

I have the following:
/*
 * dummy conversation function sending exactly one prompt
 * and expecting exactly one response from the other party
 */
static int converse(pam_handle_t *pamh,
                    struct pam_message **message,
                    struct pam_response **response)
{
    int retval;
    const struct pam_conv *conv;

    retval = pam_get_item(pamh, PAM_CONV, (const void **) &conv ) ;
    if (retval == PAM_SUCCESS)
        retval = conv->conv(1, (const struct pam_message **)message,
                            response, conv->appdata_ptr);

    return retval; /* propagate error status */
}

/*
 * This is a conversation function to obtain the user's password
 */
int conversation(pam_handle_t *pamh)
{
    struct pam_message msg[2],*pmsg[2];
    struct pam_response *resp;
    int retval;
    char * token = NULL;

    pmsg[0] = &msg[0];
    msg[0].msg_style = PAM_PROMPT_ECHO_OFF;
    msg[0].msg = "Password: ";

    /* so call the conversation expecting i responses */
    resp = NULL;
    retval = converse(pamh, pmsg, &resp);

    if (resp != NULL) {
        const char * item;
        /* interpret the response */
        if (retval == PAM_SUCCESS) {     /* a good conversation */
            token = x_strdup(resp[0].resp);
            if (token == NULL) {
                return PAM_AUTHTOK_RECOVER_ERR;
            }
        }

        /* set the auth token */
        retval = pam_set_item(pamh, PAM_AUTHTOK, token);
        token = _pam_delete(token);   /* clean it up */
        if ( (retval != PAM_SUCCESS) ||
             (retval = pam_get_item(pamh, PAM_AUTHTOK, (const void **)&item))
             != PAM_SUCCESS ) {
            return retval;
        }

        _pam_drop_reply(resp, 1);
    } else {
        retval = (retval == PAM_SUCCESS)
            ? PAM_AUTHTOK_RECOVER_ERR:retval ;
    }

    return retval;
}


Regards,
-JD-


On Wed, 17 Nov 2004 09:06:14 -0700, Jason Gerfen
<jason.gerfen at scl.utah.edu> wrote:
> Could you show me an example of a proper conversion function?
> 
> 
> 
> Jason DiCioccio wrote:
> 
> >Greetings!
> >
> >On Wed, 17 Nov 2004 08:43:47 -0700, Jason Gerfen
> ><jason.gerfen at scl.utah.edu> wrote:
> >
> >
> >>I am looking for assistance using the pam_get_item() function.
> >>According to the pam module writters guide on kernel.org I should use
> >>pam_get_item() as the following:
> >>
> >>extern int pam_get_item( const pam_handle_t *pamh,
> >>                                              int item_type,
> >>                                              const void **item );
> >>
> >>As you can see in the code below it should retrieve the password entered
> >>during login and store it in the const void **password variable.  But
> >>what happens is it completely crashes the display manager.  I don't get
> >>it, I have looked at other people's source (pam_krb5afs.c for example)
> >>and they are calling the pam_get_item() function in much the same way
> >>and yet it isn't crashing their display.  Am I missing something or over
> >>looking a compile option perhaps?  Any help is greatly appreciated.
> >>
> >>
> >
> >You need to use a conversation function first.  Take a look at some of
> >the code you  were looking at before and look for where they call
> >theri conversation functions.  You need to initiate a 'conversation'
> >with the calling program in order to receive the auth token.  You then
> >use pam_set_item to set PAM_AUTHTOK.
> >
> >I hope this made sense.  I ran into this same issue before and it was
> >driving me nuts :)
> >
> >Regards,
> >-JD-
> >
> >_______________________________________________
> >Pam-list mailing list
> >Pam-list at redhat.com
> >https://www.redhat.com/mailman/listinfo/pam-list
> >
> >
> 
> --
> Jason Gerfen
> Student Computing
> Marriott Library
> 801.585.9810
> 
> 
> jason.gerfen at scl.utah.edu
> 
> "And remember... If the ladies
>  don't find you handsome, they
>  should at least find you handy..."
>              ~The Red Green show
> 
>