pam_examples

blank.c

/*
 * $Id$
 */

/* Andrew Morgan (morgan@parc.power.net) -- a self contained `blank'
 * application
 *
 * I am not very proud of this code.  It makes use of a possibly ill-
 * defined pamh pointer to call pam_strerror() with.  The reason that
 * I was sloppy with this is historical (pam_strerror, prior to 0.59,
 * did not require a pamh argument) and if this program is used as a
 * model for anything, I should wish that you will take this error into
 * account.
 */

#include <stdio.h>
#include <stdlib.h>

#include <security/pam_appl.h>
#include <security/pam_misc.h>

/* ------ some local (static) functions ------- */

static void bail_out(pam_handle_t *pamh, int really, int code, const char *fn)
{
     fprintf(stderr,"==> called %s()\n  got: `%s'\n", fn,
         pam_strerror(pamh, code));
     if (really && code)
      exit ();
}

/* ------ some static data objects ------- */

static struct pam_conv conv = {
     misc_conv,
     NULL
};

/* ------- the application itself -------- */

int main(int argc, char **argv)
{
     pam_handle_t *pamh=NULL;
     char *username=NULL;
     int retcode;

     /* did the user call with a username as an argument ? */

     if (argc > ) {
      fprintf(stderr,"usage: %s [username]\n",argv[]);
     } else if (argc == ) {
      username = argv[];
     }

     /* initialize the Linux-PAM library */
     retcode = pam_start("blank", username, &conv, &pamh);
     bail_out(pamh,,retcode,"pam_start");

     /* test the environment stuff */
     {
#define MAXENV 15
     const char *greek[MAXENV] = {
         "a=alpha", "b=beta", "c=gamma", "d=delta", "e=epsilon",
         "f=phi", "g=psi", "h=eta", "i=iota", "j=mu", "k=nu",
         "l=zeta", "h=", "d", "k=xi"
     };
     char **env;
     int i;

     for (i=; i<MAXENV; ++i) {
         retcode = pam_putenv(pamh,greek[i]);
         bail_out(pamh,,retcode,"pam_putenv");
     }
     env = pam_getenvlist(pamh);
     if (env)
         env = pam_misc_drop_env(env);
     else
         fprintf(stderr,"???\n");
     fprintf(stderr,"a test: c=[%s], j=[%s]\n"
         , pam_getenv(pamh, "c"), pam_getenv(pamh, "j"));
     }

     /* to avoid using goto we abuse a loop here */
     for (;;) {
      /* authenticate the user --- `0' here, could have been PAM_SILENT
       *    | PAM_DISALLOW_NULL_AUTHTOK */

      retcode = pam_authenticate(pamh, );
      bail_out(pamh,,retcode,"pam_authenticate");

      /* has the user proved themself valid? */
      if (retcode != PAM_SUCCESS) {
           fprintf(stderr,"%s: invalid request\n",argv[]);
           break;
      }

      /* the user is valid, but should they have access at this
         time? */

      retcode = pam_acct_mgmt(pamh, ); /* `0' could be as above */
      bail_out(pamh,,retcode,"pam_acct_mgmt");

      if (retcode == PAM_NEW_AUTHTOK_REQD) {
           fprintf(stderr,"Application must request new password...\n");
           retcode = pam_chauthtok(pamh,PAM_CHANGE_EXPIRED_AUTHTOK);
           bail_out(pamh,,retcode,"pam_chauthtok");
      }

      if (retcode != PAM_SUCCESS) {
           fprintf(stderr,"%s: invalid request\n",argv[]);
           break;
      }

      /* `0' could be as above */
      retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED);
      bail_out(pamh,,retcode,"pam_setcred1");

      if (retcode != PAM_SUCCESS) {
           fprintf(stderr,"%s: problem setting user credentials\n"
               ,argv[]);
           break;
      }

      /* open a session for the user --- `0' could be PAM_SILENT */
      retcode = pam_open_session(pamh,);
      bail_out(pamh,,retcode,"pam_open_session");
      if (retcode != PAM_SUCCESS) {
           fprintf(stderr,"%s: problem opening a session\n",argv[]);
           break;
      }

      fprintf(stderr,"The user has been authenticated and `logged in'\n");

      /* close a session for the user --- `0' could be PAM_SILENT
       * it is possible that this pam_close_call is in another program..
       */

      retcode = pam_close_session(pamh,);
      bail_out(pamh,,retcode,"pam_close_session");
      if (retcode != PAM_SUCCESS) {
           fprintf(stderr,"%s: problem closing a session\n",argv[]);
           break;
      }

      retcode = pam_setcred(pamh, PAM_DELETE_CRED);
      bail_out(pamh,,retcode,"pam_setcred2");

      break;                      /* don't go on for ever! */
     }

     /* close the Linux-PAM library */
     retcode = pam_end(pamh, PAM_SUCCESS);
     pamh = NULL;

     bail_out(pamh,,retcode,"pam_end");

     exit();
}

check_user.c

/*
  $Id$

  This program was contributed by Shane Watts <shane@icarus.bofh.asn.au>
  slight modifications by AGM.

  You need to add the following (or equivalent) to the /etc/pam.conf file.
  # check authorization
  check   auth       required     pam_unix_auth.so
  check   account    required     pam_unix_acct.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 == ) {
    user = argv[];
    }

    if(argc > ) {
    fprintf(stderr, "Usage: check_user [username]\n");
    exit();
    }

    retval = pam_start("check", user, &conv, &pamh);

    if (retval == PAM_SUCCESS)
        retval = pam_authenticate(pamh, );    /* is user really user? */

    if (retval == PAM_SUCCESS)
        retval = pam_acct_mgmt(pamh, );       /* 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();
    }

    return ( retval == PAM_SUCCESS ? : );       /* indicate success */
}

vpass.c

#include "config.h"

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <pwd.h>
#include <sys/types.h>
#include <security/pam_appl.h>

static int
test_conv (int num_msg UNUSED, const struct pam_message **msgm UNUSED,
       struct pam_response **response UNUSED, void *appdata_ptr UNUSED)
{
    return ;
}

static struct pam_conv conv = {
    test_conv,
    NULL
};

int main(void)
{
    char *user;
    pam_handle_t *pamh;
    struct passwd *pw;
    uid_t uid;
    int res;

    uid = geteuid();
    pw = getpwuid(uid);
    if (pw) {
    user = pw->pw_name;
    } else {
    fprintf(stderr, "Invalid userid: %lu\n", (unsigned long) uid);
    exit();
    }

    pam_start("vpass", user, &conv, &pamh);
    pam_set_item(pamh, PAM_TTY, "/dev/tty");
    if ((res = pam_authenticate(pamh, )) != PAM_SUCCESS) {
    fprintf(stderr, "Oops: %s\n", pam_strerror(pamh, res));
    exit();
    }

    pam_end(pamh, res);
    exit();
}

xsh.c

/* Andrew Morgan (morgan@kernel.org) -- an example application
 * that invokes a shell, based on blank.c */

#include "config.h"

#include <stdio.h>
#include <stdlib.h>

#include <security/pam_appl.h>
#include <security/pam_misc.h>

#include <pwd.h>
#include <sys/types.h>
#include <unistd.h>

/* ------ some local (static) functions ------- */

static void bail_out(pam_handle_t *pamh,int really, int code, const char *fn)
{
     fprintf(stderr,"==> called %s()\n  got: `%s'\n", fn,
         pam_strerror(pamh,code));
     if (really && code)
      exit ();
}

/* ------ some static data objects ------- */

static struct pam_conv conv = {
     misc_conv,
     NULL
};

/* ------- the application itself -------- */

int main(int argc, char **argv)
{
     pam_handle_t *pamh=NULL;
     const void *username=NULL;
     const char *service="xsh";
     int retcode;

     /* did the user call with a username as an argument ?
      * did they also */

     if (argc > ) {
      fprintf(stderr,"usage: %s [username [service-name]]\n",argv[]);
     }
     if ((argc >= ) && (argv[][] != '-')) {
      username = argv[];
     }
     if (argc == ) {
     service = argv[];
     }

     /* initialize the Linux-PAM library */
     retcode = pam_start(service, username, &conv, &pamh);
     bail_out(pamh,,retcode,"pam_start");

     /* fill in the RUSER and RHOST etc. fields */
     {
     char buffer[];
     struct passwd *pw;
     const char *tty;

     pw = getpwuid(getuid());
     if (pw != NULL) {
         retcode = pam_set_item(pamh, PAM_RUSER, pw->pw_name);
         bail_out(pamh,,retcode,"pam_set_item(PAM_RUSER)");
     }

     retcode = gethostname(buffer, sizeof(buffer)-);
     if (retcode) {
         perror("failed to look up hostname");
         retcode = pam_end(pamh, PAM_ABORT);
         bail_out(pamh,,retcode,"pam_end");
     }
     retcode = pam_set_item(pamh, PAM_RHOST, buffer);
     bail_out(pamh,,retcode,"pam_set_item(PAM_RHOST)");

     tty = ttyname(fileno(stdin));
     if (tty) {
         retcode = pam_set_item(pamh, PAM_TTY, tty);
         bail_out(pamh,,retcode,"pam_set_item(PAM_RHOST)");
     }
     }

     /* to avoid using goto we abuse a loop here */
     for (;;) {
      /* authenticate the user --- `0' here, could have been PAM_SILENT
       *    | PAM_DISALLOW_NULL_AUTHTOK */

      retcode = pam_authenticate(pamh, );
      bail_out(pamh,,retcode,"pam_authenticate");

      /* has the user proved themself valid? */
      if (retcode != PAM_SUCCESS) {
           fprintf(stderr,"%s: invalid request\n",argv[]);
           break;
      }

      /* the user is valid, but should they have access at this
         time? */

      retcode = pam_acct_mgmt(pamh, ); /* `0' could be as above */
      bail_out(pamh,,retcode,"pam_acct_mgmt");

      if (retcode == PAM_NEW_AUTHTOK_REQD) {
           fprintf(stderr,"Application must request new password...\n");
           retcode = pam_chauthtok(pamh,PAM_CHANGE_EXPIRED_AUTHTOK);
           bail_out(pamh,,retcode,"pam_chauthtok");
      }

      if (retcode != PAM_SUCCESS) {
           fprintf(stderr,"%s: invalid request\n",argv[]);
           break;
      }

      /* `0' could be as above */
      retcode = pam_setcred(pamh, PAM_ESTABLISH_CRED);
      bail_out(pamh,,retcode,"pam_setcred");

      if (retcode != PAM_SUCCESS) {
           fprintf(stderr,"%s: problem setting user credentials\n"
               ,argv[]);
           break;
      }

      /* open a session for the user --- `0' could be PAM_SILENT */
      retcode = pam_open_session(pamh,);
      bail_out(pamh,,retcode,"pam_open_session");
      if (retcode != PAM_SUCCESS) {
           fprintf(stderr,"%s: problem opening a session\n",argv[]);
           break;
      }

      pam_get_item(pamh, PAM_USER, &username);
      fprintf(stderr,
          "The user [%s] has been authenticated and `logged in'\n",
          (const char *)username);

      /* this is always a really bad thing for security! */
      retcode = system("/bin/sh");

      /* close a session for the user --- `0' could be PAM_SILENT
       * it is possible that this pam_close_call is in another program..
       */

      retcode = pam_close_session(pamh,);
      bail_out(pamh,,retcode,"pam_close_session");
      if (retcode != PAM_SUCCESS) {
           fprintf(stderr,"%s: problem closing a session\n",argv[]);
           break;
      }

      /* `0' could be as above */
      retcode = pam_setcred(pamh, PAM_DELETE_CRED);
      bail_out(pamh,,retcode,"pam_setcred");
      if (retcode != PAM_SUCCESS) {
           fprintf(stderr,"%s: problem deleting user credentials\n"
               ,argv[]);
           break;
      }

      break;                      /* don't go on for ever! */
     }

     /* close the Linux-PAM library */
     retcode = pam_end(pamh, PAM_SUCCESS);
     pamh = NULL;
     bail_out(pamh,,retcode,"pam_end");

     return ();
}