/*      $NetBSD: pam_passwd.c,v 1.7 2021/09/10 21:52:18 rillig Exp $    */

/*-
* Copyright (c) 2002 Networks Associates Technologies, Inc.
* All rights reserved.
*
* This software was developed for the FreeBSD Project by ThinkSec AS and
* NAI Labs, the Security Research Division of Network Associates, Inc.
* under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
* DARPA CHATS research program.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote
*    products derived from this software without specific prior written
*    permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#include <sys/cdefs.h>
#ifdef __FreeBSD__
__FBSDID("$FreeBSD: src/usr.bin/passwd/passwd.c,v 1.23 2003/04/18 21:27:09 nectar Exp $");
#else
__RCSID("$NetBSD: pam_passwd.c,v 1.7 2021/09/10 21:52:18 rillig Exp $");
#endif

#include <sys/param.h>

#include <err.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <syslog.h>
#include <unistd.h>

#include "extern.h"

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

static pam_handle_t *pamh;
static struct pam_conv pamc = {
       openpam_ttyconv,
       NULL
};

#define pam_check(msg)                                                  \
do {                                                                    \
       if (pam_err != PAM_SUCCESS) {                                   \
               warnx("%s: %s", (msg), pam_strerror(pamh, pam_err));    \
               goto end;                                               \
       }                                                               \
} while (0)

void
pwpam_process(const char *username, int argc, char **argv)
{
       int ch, pam_err;
       char hostname[MAXHOSTNAMELEN + 1];

       /* details about the invoking user for logging */
       const uid_t i_uid = getuid();
       const struct passwd *const i_pwd = getpwuid(i_uid);
       const char *const i_username = (i_pwd && i_pwd->pw_name)
               ? i_pwd->pw_name : "(null)";

       while ((ch = getopt(argc, argv, "")) != -1) {
               switch (ch) {
               default:
                       usage();
                       /* NOTREACHED */
               }
       }

       argc -= optind;
       argv += optind;

       switch (argc) {
       case 0:
               /* username already provided */
               break;
       case 1:
               username = argv[0];
               break;
       default:
               usage();
               /* NOTREACHED */
       }

       (void)printf("Changing password for %s.\n", username);

       /* initialize PAM -- always use the program name "passwd" */
       pam_err = pam_start("passwd", username, &pamc, &pamh);
       if (pam_err != PAM_SUCCESS)
               errx(1, "unable to start PAM session: %s",
                   pam_strerror(NULL, pam_err));

       pam_err = pam_set_item(pamh, PAM_TTY, ttyname(STDERR_FILENO));
       pam_check("unable to set TTY");

       (void)gethostname(hostname, sizeof hostname);
       pam_err = pam_set_item(pamh, PAM_RHOST, hostname);
       pam_check("unable to set RHOST");

       pam_err = pam_set_item(pamh, PAM_RUSER, getlogin());
       pam_check("unable to set RUSER");

       /* set new password */
       pam_err = pam_chauthtok(pamh, 0);
       if (pam_err != PAM_SUCCESS) {
               if (pam_err == PAM_PERM_DENIED) {
                       syslog(LOG_AUTH | LOG_NOTICE,
                              "user %s (UID %lu) failed to change the "
                              "PAM authentication token of user %s: %s",
                              i_username, (unsigned long)i_uid, username,
                              pam_strerror(pamh, pam_err));
               }
               printf("Unable to change auth token: %s\n",
                   pam_strerror(pamh, pam_err));
       } else {
               syslog(LOG_AUTH | LOG_INFO,
                      "user %s (UID %lu) successfully changed the "
                      "PAM authentication token of user %s",
                      i_username, (unsigned long)i_uid, username);
       }

end:
       pam_end(pamh, pam_err);
       if (pam_err == PAM_SUCCESS)
               return;
       exit(1);
}