usr.bin/login/klogin.c

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * 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 the University of
 *      California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */

#ifndef lint
static char sccsid[] = "@(#)klogin.c    5.11 (Berkeley) 7/12/92";
#endif /* not lint */

#ifdef KERBEROS
#include <sys/param.h>
#include <sys/syslog.h>
#include <kerberosIV/des.h>
#include <kerberosIV/krb.h>
#include <pwd.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#define INITIAL_TICKET  "krbtgt"
#define VERIFY_SERVICE  "rcmd"

extern int notickets;
extern char *krbtkfile_env;

/*
 * Attempt to log the user in using Kerberos authentication
 *
 * return 0 on success (will be logged in)
 *        1 if Kerberos failed (try local password in login)
 */
int
klogin(pw, instance, localhost, password)
        struct passwd *pw;
        char *instance, *localhost, *password;
{
        int kerror;
        AUTH_DAT authdata;
        KTEXT_ST ticket;
        struct hostent *hp;
        unsigned long faddr;
        char realm[REALM_SZ], savehost[MAXHOSTNAMELEN];
        char tkt_location[MAXPATHLEN];
        char *krb_get_phost();

        /*
         * Root logins don't use Kerberos.
         * If we have a realm, try getting a ticket-granting ticket
         * and using it to authenticate.  Otherwise, return
         * failure so that we can try the normal passwd file
         * for a password.  If that's ok, log the user in
         * without issuing any tickets.
         */
        if (strcmp(pw->pw_name, "root") == 0 ||
            krb_get_lrealm(realm, 0) != KSUCCESS)
                return (1);

        /*
         * get TGT for local realm
         * tickets are stored in a file named TKT_ROOT plus uid
         * except for user.root tickets.
         */

        if (strcmp(instance, "root") != 0)
                (void)sprintf(tkt_location, "%s%d", TKT_ROOT, pw->pw_uid);
        else {
                (void)sprintf(tkt_location, "%s_root_%d", TKT_ROOT, pw->pw_uid);
                krbtkfile_env = tkt_location;
        }
        (void)krb_set_tkt_string(tkt_location);

        /*
         * Set real as well as effective ID to 0 for the moment,
         * to make the kerberos library do the right thing.
         */
        if (setuid(0) < 0) {
                perror("login: setuid");
                return (1);
        }
        kerror = krb_get_pw_in_tkt(pw->pw_name, instance,
                    realm, INITIAL_TICKET, realm, DEFAULT_TKT_LIFE, password);
        /*
         * If we got a TGT, get a local "rcmd" ticket and check it so as to
         * ensure that we are not talking to a bogus Kerberos server.
         *
         * There are 2 cases where we still allow a login:
         *      1: the VERIFY_SERVICE doesn't exist in the KDC
         *      2: local host has no srvtab, as (hopefully) indicated by a
         *         return value of RD_AP_UNDEC from krb_rd_req().
         */
        if (kerror != INTK_OK) {
                if (kerror != INTK_BADPW && kerror != KDC_PR_UNKNOWN) {
                        syslog(LOG_ERR, "Kerberos intkt error: %s",
                            krb_err_txt[kerror]);
                        dest_tkt();
                }
                return (1);
        }

        if (chown(TKT_FILE, pw->pw_uid, pw->pw_gid) < 0)
                syslog(LOG_ERR, "chown tkfile (%s): %m", TKT_FILE);

        (void)strncpy(savehost, krb_get_phost(localhost), sizeof(savehost));
        savehost[sizeof(savehost)-1] = NULL;

        /*
         * if the "VERIFY_SERVICE" doesn't exist in the KDC for this host,
         * still allow login with tickets, but log the error condition.
         */

        kerror = krb_mk_req(&ticket, VERIFY_SERVICE, savehost, realm, 33);
        if (kerror == KDC_PR_UNKNOWN) {
                syslog(LOG_NOTICE,
                    "warning: TGT not verified (%s); %s.%s not registered, or srvtab is wrong?",
                    krb_err_txt[kerror], VERIFY_SERVICE, savehost);
                notickets = 0;
                return(0);
        }

        if (kerror != KSUCCESS) {
                (void)printf("unable to use TGT: (%s)\n", krb_err_txt[kerror]);
                syslog(LOG_NOTICE, "unable to use TGT: (%s)",
                    krb_err_txt[kerror]);
                dest_tkt();
                return(1);
        }

        if (!(hp = gethostbyname(localhost))) {
                syslog(LOG_ERR, "couldn't get local host address");
                dest_tkt();
                return(1);
        }

        bcopy((void *)hp->h_addr, (void *)&faddr, sizeof(faddr));

        kerror = krb_rd_req(&ticket, VERIFY_SERVICE, savehost, faddr,
            &authdata, "");

        if (kerror == KSUCCESS) {
                notickets = 0;
                return(0);
        }

        /* undecipherable: probably didn't have a srvtab on the local host */
        if (kerror = RD_AP_UNDEC) {
                syslog(LOG_NOTICE, "krb_rd_req: (%s)\n", krb_err_txt[kerror]);
                dest_tkt();
                return(1);
        }
        /* failed for some other reason */
        (void)printf("unable to verify %s ticket: (%s)\n", VERIFY_SERVICE,
            krb_err_txt[kerror]);
        syslog(LOG_NOTICE, "couldn't verify %s ticket: %s", VERIFY_SERVICE,
            krb_err_txt[kerror]);
        dest_tkt();
        return(1);
}
#endif