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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Chapter 8. An example application</title><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot"><link rel="home" href="Linux-PAM_ADG.html" title="The Linux-PAM Application Developers' Guide"><link rel="up" href="Linux-PAM_ADG.html" title="The Linux-PAM Application Developers' Guide"><link rel="prev" href="adg-glossary.html" title="Chapter 7. Glossary of PAM related terms"><link rel="next" href="adg-files.html" title="Chapter 9. Files"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 8. An example application</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="adg-glossary.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="adg-files.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="adg-example"></a>Chapter 8. An example application</h1></div></div></div><p>
      To get a flavor of the way a <span class="emphasis"><em>Linux-PAM</em></span>
      application is written we include the following example. It prompts
      the user for their password and indicates whether their account
      is valid on the standard output, its return code also indicates
      the success (<span class="returnvalue">0</span> for success;
      <span class="returnvalue">1</span> for failure).
    </p><pre class="programlisting">
/*
  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 &lt;security/pam_appl.h&gt;
#include &lt;security/pam_misc.h&gt;
#include &lt;stdio.h&gt;

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 &gt; 2) {
        fprintf(stderr, "Usage: check_user [username]\n");
        exit(1);
    }

    retval = pam_start("check_user", user, &amp;conv, &amp;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 */
}

    </pre></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="adg-glossary.html">Prev</a> </td><td width="20%" align="center"> </td><td width="40%" align="right"> <a accesskey="n" href="adg-files.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 7. Glossary of PAM related terms </td><td width="20%" align="center"><a accesskey="h" href="Linux-PAM_ADG.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 9. Files</td></tr></table></div></body></html>