/*      $OpenBSD: login_passwd.c,v 1.20 2021/11/16 21:55:21 deraadt Exp $       */

/*-
 * Copyright (c) 1995 Berkeley Software Design, Inc. All rights reserved.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Berkeley Software Design,
 *      Inc.
 * 4. The name of Berkeley Software Design, Inc.  may not be used to endorse
 *    or promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN, INC. ``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 BERKELEY SOFTWARE DESIGN, INC. 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.
 *
 *      BSDI $From: login_passwd.c,v 1.11 1997/08/08 18:58:24 prb Exp $
 */

#include <sys/types.h>
#include <sys/resource.h>

#include <errno.h>
#include <pwd.h>
#include <readpassphrase.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <util.h>

#include <login_cap.h>

int
main(int argc, char *argv[])
{
        FILE *back = NULL;
        char *class = NULL, *username = NULL, *wheel = NULL;
        char response[1024], pbuf[1024], *pass = "";
        int ch, rc, mode = 0, lastchance = 0;
        struct passwd *pwd;

        (void)signal(SIGQUIT, SIG_IGN);
        (void)signal(SIGINT, SIG_IGN);
        (void)setpriority(PRIO_PROCESS, 0, 0);

        openlog(NULL, LOG_ODELAY, LOG_AUTH);

        while ((ch = getopt(argc, argv, "ds:v:")) != -1) {
                switch (ch) {
                case 'd':
                        back = stdout;
                        break;
                case 's':       /* service */
                        if (strcmp(optarg, "login") == 0)
                                mode = 0;
                        else if (strcmp(optarg, "challenge") == 0)
                                mode = 1;
                        else if (strcmp(optarg, "response") == 0)
                                mode = 2;
                        else {
                                syslog(LOG_ERR, "%s: invalid service", optarg);
                                exit(1);
                        }
                        break;
                case 'v':
                        if (strncmp(optarg, "wheel=", 6) == 0)
                                wheel = optarg + 6;
                        else if (strncmp(optarg, "lastchance=", 11) == 0)
                                lastchance = (strcmp(optarg + 11, "yes") == 0);
                        break;
                default:
                        syslog(LOG_ERR, "usage error");
                        exit(1);
                }
        }

        switch (argc - optind) {
        case 2:
                class = argv[optind + 1];
                /* FALLTHROUGH */
        case 1:
                username = argv[optind];
                break;
        default:
                syslog(LOG_ERR, "usage error");
                exit(1);
        }

        /* get the password hash before pledge(2) or it will return '*' */
        pwd = getpwnam_shadow(username);

        if (pledge("stdio rpath tty id", NULL) == -1) {
                syslog(LOG_ERR, "pledge: %m");
                exit(1);
        }

        if (back == NULL && (back = fdopen(3, "r+")) == NULL) {
                syslog(LOG_ERR, "reopening back channel: %m");
                exit(1);
        }
        if (wheel != NULL && strcmp(wheel, "yes") != 0) {
                fprintf(back, BI_VALUE " errormsg %s\n",
                    "you are not in group wheel");
                goto reject;
        }

        if (mode == 1) {
                fprintf(back, BI_SILENT "\n");
                exit(0);
        }

        (void)setpriority(PRIO_PROCESS, 0, -4);

        if (mode == 2) {
                mode = 0;
                ch = -1;
                while (++ch < sizeof(response) &&
                    read(3, &response[ch], 1) == 1) {
                        if (response[ch] == '\0' && ++mode == 2)
                                break;
                        if (response[ch] == '\0' && mode == 1)
                                pass = response + ch + 1;
                }
                if (mode < 2) {
                        syslog(LOG_ERR, "protocol error on back channel");
                        exit(1);
                }
        } else {
                if (pwd == NULL || *pwd->pw_passwd != '\0') {
                        pass = readpassphrase("Password:", pbuf, sizeof(pbuf),
                            RPP_ECHO_OFF);
                        if (pass == NULL)
                                goto reject;
                }
        }

        if (pledge("stdio rpath", NULL) == -1) {
                syslog(LOG_ERR, "pledge: %m");
                exit(1);
        }

        rc = crypt_checkpass(pass, pwd ? pwd->pw_passwd : NULL);
        explicit_bzero(pass, strlen(pass));
        if (rc == 0) {
                if (login_check_expire(back, pwd, class, lastchance) == 0) {
                    fprintf(back, BI_AUTH "\n");
                    exit(0);
                }
        }
reject:
        fprintf(back, BI_REJECT "\n");
        exit(1);
}