A problem using pam library in C

["Chu Qiu" <qiu.chu@xxxxxxxxxxx>]

I'm studying on pam library , and I run the code given by "The Linux-PAM Application Developer's Guide" on redhat linux.

 

"retval = pam_authenticate(pamh, 0);" is running successfully

 

but the next "retval = pam_acct_mgmt(pamh, 0);" return "PAM_AUTHINFO_UNAVAIL"

 

I don't know what problem is it? Please do me a favour.

 

Thank you very much

 

Chu Qiu

 

This is the code, and the service file is the same as what mentioned in this code

/*
This program was contributed by Shane Watts
[modifications by AGM and kukuk]
You need to add the following (or equivalent) to the
/etc/pam.d/check_user file:
# check authorization
auth required pam_unix.so
account required pam_unix.so
*/
#include <security/pam_appl.h>
#include <security/pam_misc.h>
#include <stdio.h>
static struct pam_conv conv = {
misc_conv,
NULL
};
int main(int argc, char *argv[])
{
pam_handle_t *pamh=NULL;
int retval;
const char *user="nobody";
if(argc == 2) {
user = argv[1];
}
if(argc > 2) {
fprintf(stderr, "Usage: check_user [username]\n");
exit(1);
}
retval = pam_start("check_user", user, &conv, &pamh);
if (retval == PAM_SUCCESS)
retval = pam_authenticate(pamh, 0); /* is user really user? */

 

if (retval == PAM_SUCCESS)
retval = pam_acct_mgmt(pamh, 0); /* permitted access? */

/* This is where we have been authorized or not. */
if (retval == PAM_SUCCESS) {
fprintf(stdout, "Authenticated\n");
} else {
fprintf(stdout, "Not Authenticated\n");
}
if (pam_end(pamh,retval) != PAM_SUCCESS) { /* close Linux-PAM */
pamh = NULL;
fprintf(stderr, "check_user: failed to release authenticator\n");
exit(1);
}
return ( retval == PAM_SUCCESS ? 0:1 ); /* indicate success */
}

 

 

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