/*      $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);
}