cmd-inet/usr.sbin/in.rshd.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1983-1989 AT&T    */
/*    All Rights Reserved   */

/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

#define _FILE_OFFSET_BITS 64

/*
 * remote shell server:
 *  remuser\0
 *  locuser\0
 *  command\0
 *  data
 */
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/telioctl.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/select.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <stdarg.h>
#include <errno.h>
#include <pwd.h>
#include <grp.h>
#include <signal.h>
#include <netdb.h>
#include <syslog.h>
#include <fcntl.h>
#include <ctype.h>
#include <locale.h>

#include <sys/resource.h>
#include <sys/filio.h>
#include <shadow.h>
#include <stdlib.h>

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

#include <k5-int.h>
#include <krb5_repository.h>
#include <com_err.h>
#include <kcmd.h>

#include <addr_match.h>
#include <store_forw_creds.h>

#ifndef NCARGS
#define NCARGS  5120
#endif /* !NCARGS */

static void error(char *, ...);
static void doit(int, struct sockaddr_storage *, char **);
static void getstr(int, char *, int, char *);

static int legalenvvar(char *);
static void add_to_envinit(char *);
static int locale_envmatch(char *, char *);

/* Function decls. for functions not in any header file.  (Grrrr.) */
extern int audit_rshd_setup(void);
extern int audit_rshd_success(char *, char *, char *, char *);
extern int audit_rshd_fail(char *, char *, char *, char *, char *);
extern int audit_settid(int);

static int do_encrypt = 0;
static pam_handle_t *pamh;

/*
 * This is the shell/kshell daemon. The very basic protocol for checking
 * authentication and authorization is:
 * 1) Check authentication.
 * 2) Check authorization via the access-control files:
 *    ~/.k5login (using krb5_kuserok) and/or
 * Execute command if configured authoriztion checks pass, else deny
 * permission.
 *
 * The configuration is done either by command-line arguments passed by inetd,
 * or by the name of the daemon. If command-line arguments are present, they
 * take priority. The options are:
 * -k allow kerberos authentication (krb5 only; krb4 support is not provided)
 * -5 same as `-k', mainly for compatability with MIT
 * -e allow encrypted session
 * -c demand authenticator checksum
 * -i ignore authenticator checksum
 * -U Refuse connections that cannot be mapped to a name via `gethostbyname'
 * -s <tos> Set the IP TOS option
 * -S <keytab>  Set the keytab file to use
 * -M <realm>   Set the Kerberos realm to use
 */

#define ARGSTR  "ek5ciUD:M:S:L:?:"
#define RSHD_BUFSIZ (50 * 1024)

static krb5_context bsd_context;
static krb5_keytab keytab = NULL;
static krb5_ccache ccache = NULL;
static krb5_keyblock *sessionkey = NULL;

static int require_encrypt = 0;
static int resolve_hostname = 0;
static int krb5auth_flag = 0;   /* Flag set, when KERBEROS is enabled */
static enum kcmd_proto kcmd_protocol;

#ifdef DEBUG
static int debug_port = 0;
#endif /* DEBUG */

/*
 * There are two authentication related masks:
 * auth_ok and auth_sent.
 * The auth_ok mask is the or'ing of authentication
 * systems any one of which can be used.
 * The auth_sent mask is the or'ing of one or more authentication/authorization
 * systems that succeeded.  If the and'ing
 * of these two masks is true, then authorization is successful.
 */

#define AUTH_KRB5   (0x2)
static int auth_ok = 0;
static int auth_sent = 0;
static int checksum_required = 0;
static int checksum_ignored = 0;

/*
 * Leave room for 4 environment variables to be passed.
 * The "-L env_var" option has been added primarily to
 * maintain compatability with MIT.
 */
#define MAXENV  4
static char *save_env[MAXENV];
static int num_env = 0;

static void usage(void);
static krb5_error_code recvauth(int, int *);

/*ARGSUSED*/
int
main(int argc, char **argv, char **renvp)
{
    struct linger linger;
    int on = 1, fromlen;
    struct sockaddr_storage from;
    int fd = 0;

    extern int opterr, optind;
    extern char *optarg;
    int ch;
    int tos = -1;
    krb5_error_code status;

    openlog("rsh", LOG_PID | LOG_ODELAY, LOG_DAEMON);
    (void) audit_rshd_setup();  /* BSM */
    fromlen = sizeof (from);

    (void) setlocale(LC_ALL, "");

    /*
     * Analyze parameters.
     */
    opterr = 0;
    while ((ch = getopt(argc, argv, ARGSTR)) != EOF)
        switch (ch) {
        case '5':
        case 'k':
            auth_ok |= AUTH_KRB5;
            krb5auth_flag++;
            break;

        case 'c':
            checksum_required = 1;
            krb5auth_flag++;
            break;
        case 'i':
            checksum_ignored = 1;
            krb5auth_flag++;
            break;

        case 'e':
            require_encrypt = 1;
            krb5auth_flag++;
            break;
#ifdef DEBUG
        case 'D':
            debug_port = atoi(optarg);
            break;
#endif /* DEBUG */
        case 'U':
            resolve_hostname = 1;
            break;

        case 'M':
            (void) krb5_set_default_realm(bsd_context, optarg);
            krb5auth_flag++;
            break;

        case 'S':
            if ((status = krb5_kt_resolve(bsd_context, optarg,
                &keytab))) {
                com_err("rsh", status,
                    gettext("while resolving "
                        "srvtab file %s"), optarg);
                exit(2);
            }
            krb5auth_flag++;
            break;

        case 's':
            if (optarg == NULL || ((tos = atoi(optarg)) < 0) ||
                (tos > 255)) {
                syslog(LOG_ERR, "rshd: illegal tos value: "
                    "%s\n", optarg);
            }
            break;

        case 'L':
            if (num_env < MAXENV) {
                save_env[num_env] = strdup(optarg);
                if (!save_env[num_env++]) {
                    com_err("rsh", ENOMEM,
                        gettext("in saving env"));
                    exit(2);
                }
            } else {
                (void) fprintf(stderr, gettext("rshd: Only %d"
                        " -L arguments allowed\n"),
                        MAXENV);
                exit(2);
            }
            break;

        case '?':
        default:
            usage();
            exit(1);
            break;
        }

    if (optind == 0) {
        usage();
        exit(1);
    }
    argc -= optind;
    argv += optind;

    if (krb5auth_flag > 0) {
        status = krb5_init_context(&bsd_context);
        if (status) {
            syslog(LOG_ERR, "Error initializing krb5: %s",
                error_message(status));
            exit(1);
        }
    }

    if (!checksum_required && !checksum_ignored)
        checksum_ignored = 1;

    if (checksum_required && checksum_ignored) {
        syslog(LOG_CRIT, gettext("Checksums are required and ignored."
        "These options are mutually exclusive"
        "--check the documentation."));
        error("Configuration error: mutually exclusive "
                "options specified.\n");
        exit(1);
    }

#ifdef DEBUG
    if (debug_port) {
        int s;
        struct sockaddr_in sin;

        if ((s = socket(AF_INET, SOCK_STREAM, PF_UNSPEC)) < 0) {
            fprintf(stderr, gettext("Error in socket: %s\n"),
                    strerror(errno));
            exit(2);
        }
        (void) memset((char *)&sin, 0, sizeof (sin));
        sin.sin_family = AF_INET;
        sin.sin_port = htons(debug_port);
        sin.sin_addr.s_addr = INADDR_ANY;

        (void) setsockopt(s, SOL_SOCKET, SO_REUSEADDR,
            (char *)&on, sizeof (on));

        if ((bind(s, (struct sockaddr *)&sin, sizeof (sin))) < 0) {
            (void) fprintf(stderr, gettext("Error in bind: %s\n"),
                    strerror(errno));
            exit(2);
        }
        if ((listen(s, 5)) < 0) {
            (void) fprintf(stderr, gettext("Error in listen: %s\n"),
                    strerror(errno));
            exit(2);
        }
        if ((fd = accept(s, (struct sockaddr *)&from,
                    &fromlen)) < 0) {
            (void) fprintf(stderr, gettext("Error in accept: %s\n"),
                    strerror(errno));
            exit(2);
        }
        (void) close(s);
    }
    else
#endif /* DEBUG */
    {
        if (getpeername(STDIN_FILENO, (struct sockaddr *)&from,
                (socklen_t *)&fromlen) < 0) {
            (void) fprintf(stderr, "rshd: ");
            perror("getpeername");
            _exit(1);
        }
        fd = STDIN_FILENO;
    }

    if (audit_settid(fd) != 0) {
        perror("settid");
        exit(1);
    }

    if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, (char *)&on,
        sizeof (on)) < 0)
        syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");
    linger.l_onoff = 1;
    linger.l_linger = 60;           /* XXX */
    if (setsockopt(fd, SOL_SOCKET, SO_LINGER, (char *)&linger,
        sizeof (linger)) < 0)
        syslog(LOG_WARNING, "setsockopt (SO_LINGER): %m");

    if ((tos != -1) && (setsockopt(fd, IPPROTO_IP, IP_TOS, (char *)&tos,
                sizeof (tos)) < 0) &&
                (errno != ENOPROTOOPT)) {
        syslog(LOG_ERR, "setsockopt (IP_TOS %d): %m");
    }

    doit(dup(fd), &from, renvp);
    return (0);
}

/*
 * locale environments to be passed to shells.
 */
static char *localeenv[] = {
    "LANG",
    "LC_CTYPE", "LC_NUMERIC", "LC_TIME", "LC_COLLATE",
    "LC_MONETARY", "LC_MESSAGES", "LC_ALL", NULL};

/*
 * The following is for the environment variable list
 * used in the call to execle().  envinit is declared here,
 * but populated after the call to getpwnam().
 */
static char *homedir;   /* "HOME=" */
static char *shell;     /* "SHELL=" */
static char *username;  /* "USER=" */
static char *tz;        /* "TZ=" */

static char homestr[] = "HOME=";
static char shellstr[] = "SHELL=";
static char userstr[] = "USER=";
static char tzstr[] = "TZ=";

static char **envinit;
#define PAM_ENV_ELIM    16  /* allow 16 PAM environment variables */
#define USERNAME_LEN    16  /* maximum number of characters in user name */

/*
 *  See PSARC opinion 1992/025
 */
static char userpath[] = "PATH=/usr/bin:";
static char rootpath[] = "PATH=/usr/sbin:/usr/bin";

static char cmdbuf[NCARGS+1];
static char hostname [MAXHOSTNAMELEN + 1];
static char locuser[USERNAME_LEN + 1];
static char remuser[USERNAME_LEN + 1];

#define KRB5_RECVAUTH_V5    5
#define SIZEOF_INADDR sizeof    (struct in_addr)

#define MAX_REPOSITORY_LEN  255
static char repository[MAX_REPOSITORY_LEN];

static char *kremuser;
static krb5_principal client = NULL;

static char remote_addr[64];
static char local_addr[64];

#define _PATH_DEFAULT_LOGIN "/etc/default/login"

static void
doit(int f, struct sockaddr_storage *fromp, char **renvp)
{
    char *cp;

    struct passwd *pwd;
    char *path;
    char *tzenv;
    struct spwd *shpwd;
    struct stat statb;
    char **lenvp;

    krb5_error_code status;
    int valid_checksum;
    int cnt;
    int sin_len;
    struct sockaddr_in localaddr;

    int s;
    in_port_t port;
    pid_t pid;
    int pv[2], pw[2], px[2], cc;
    char buf[RSHD_BUFSIZ];
    char sig;
    int one = 1;
    int v = 0;
    int err = 0;
    int idx = 0;
    char **pam_env;
    char abuf[INET6_ADDRSTRLEN];
    struct sockaddr_in *sin;
    struct sockaddr_in6 *sin6;
    int fromplen;
    int homedir_len, shell_len, username_len, tz_len;
    int no_name;
    boolean_t bad_port;
    int netf = 0;

    (void) signal(SIGINT, SIG_DFL);
    (void) signal(SIGQUIT, SIG_DFL);
    (void) signal(SIGTERM, SIG_DFL);
    (void) signal(SIGXCPU, SIG_DFL);
    (void) signal(SIGXFSZ, SIG_DFL);
    (void) sigset(SIGCHLD, SIG_IGN);
    (void) signal(SIGPIPE, SIG_DFL);
    (void) signal(SIGHUP, SIG_DFL);

#ifdef DEBUG
    {
        int t = open("/dev/tty", 2);

        if (t >= 0) {
        (void) setsid();
        (void) close(t);
        }
    }
#endif
    if (fromp->ss_family == AF_INET) {
        sin = (struct sockaddr_in *)fromp;
        port = ntohs((ushort_t)sin->sin_port);
        fromplen = sizeof (struct sockaddr_in);
    } else if (fromp->ss_family == AF_INET6) {
        sin6 = (struct sockaddr_in6 *)fromp;
        port = ntohs((ushort_t)sin6->sin6_port);
        fromplen = sizeof (struct sockaddr_in6);
    } else {
        syslog(LOG_ERR, "wrong address family\n");
        exit(1);
    }

    if (fromp->ss_family == AF_INET6) {
        if (IN6_IS_ADDR_V4MAPPED(&sin6->sin6_addr)) {
            struct in_addr ipv4_addr;

            IN6_V4MAPPED_TO_INADDR(&sin6->sin6_addr, &ipv4_addr);
            (void) inet_ntop(AF_INET, &ipv4_addr, abuf,
                sizeof (abuf));
        } else {
            (void) inet_ntop(AF_INET6, &sin6->sin6_addr, abuf,
                sizeof (abuf));
        }
    } else if (fromp->ss_family == AF_INET) {
        (void) inet_ntop(AF_INET, &sin->sin_addr, abuf, sizeof (abuf));
    }

    sin_len = sizeof (struct sockaddr_in);
    if (getsockname(f, (struct sockaddr *)&localaddr, &sin_len) < 0) {
        perror("getsockname");
        exit(1);
    }

    netf = f;

    bad_port = (port >= IPPORT_RESERVED ||
        port < (uint_t)(IPPORT_RESERVED/2));

    /* Get the name of the client side host to use later */
    no_name = (getnameinfo((const struct sockaddr *) fromp, fromplen,
        hostname, sizeof (hostname), NULL, 0, 0) != 0);

    if (bad_port || no_name != 0) {
        /*
         * If there is no host name available then use the
         * IP address to identify the host in the PAM call
         * below.  Do the same if a bad port was used, to
         * prevent untrustworthy authentication.
         */
        (void) strlcpy(hostname, abuf, sizeof (hostname));
    }

    if (no_name != 0) {
        /*
         * If the '-U' option was given on the cmd line,
         * we must be able to lookup the hostname
         */
        if (resolve_hostname) {
            syslog(LOG_ERR, "rshd: Couldn't resolve your "
                "address into a host name.\r\n Please "
                "contact your net administrator");
            exit(1);
        }
    } else {
        /*
         * Even if getnameinfo() succeeded, we still have to check
         * for spoofing.
         */
        check_address("rshd", fromp, sin, sin6, abuf, hostname,
            sizeof (hostname));
    }

    if (!krb5auth_flag && bad_port) {
        if (no_name)
            syslog(LOG_NOTICE, "connection from %s - "
                "bad port\n", abuf);
        else
            syslog(LOG_NOTICE, "connection from %s (%s) - "
                "bad port\n", hostname, abuf);
        exit(1);
    }

    (void) alarm(60);
    port = 0;
    for (;;) {
        char c;
        if ((cc = read(f, &c, 1)) != 1) {
            if (cc < 0)
                syslog(LOG_NOTICE, "read: %m");
            (void) shutdown(f, 1+1);
            exit(1);
        }
        if (c == 0)
            break;
        port = port * 10 + c - '0';
    }
    (void) alarm(0);
    if (port != 0) {
        int lport = 0;
        struct sockaddr_storage ctl_addr;
        int addrlen;

        (void) memset(&ctl_addr, 0, sizeof (ctl_addr));
        addrlen = sizeof (ctl_addr);
        if (getsockname(f, (struct sockaddr *)&ctl_addr,
            &addrlen) < 0) {
            syslog(LOG_ERR, "getsockname: %m");
            exit(1);
        }
get_port:
        /*
         * 0 means that rresvport_addr() will bind to a port in
         * the anonymous priviledged port range.
         */
        if (krb5auth_flag) {
            /*
             * Kerberos does not support IPv6 yet.
             */
            lport = IPPORT_RESERVED - 1;
        }
        s = rresvport_addr(&lport, &ctl_addr);

        if (s < 0) {
            syslog(LOG_ERR, "can't get stderr port: %m");
            exit(1);
        }
        if (!krb5auth_flag && (port >= IPPORT_RESERVED)) {
            syslog(LOG_ERR, "2nd port not reserved\n");
            exit(1);
        }
        if (fromp->ss_family == AF_INET) {
            sin->sin_port = htons((ushort_t)port);
        } else if (fromp->ss_family == AF_INET6) {
            sin6->sin6_port = htons((ushort_t)port);
        }
        if (connect(s, (struct sockaddr *)fromp, fromplen) < 0) {
            if (errno == EADDRINUSE) {
                (void) close(s);
                goto get_port;
            }
            syslog(LOG_INFO, "connect second port: %m");
            exit(1);
        }
    }
    (void) dup2(f, 0);
    (void) dup2(f, 1);
    (void) dup2(f, 2);

#ifdef DEBUG
    syslog(LOG_NOTICE, "rshd: Client hostname = %s", hostname);
    if (debug_port)
        syslog(LOG_NOTICE, "rshd: Debug port is %d", debug_port);
    if (krb5auth_flag > 0)
        syslog(LOG_NOTICE, "rshd: Kerberos mode is ON");
    else
        syslog(LOG_NOTICE, "rshd: Kerberos mode is OFF");
#endif /* DEBUG */

    if (krb5auth_flag > 0) {
        if ((status = recvauth(f, &valid_checksum))) {
            syslog(LOG_ERR, gettext("Kerberos Authentication "
                    "failed \n"));
            error("Authentication failed: %s\n",
                    error_message(status));
            (void) audit_rshd_fail("Kerberos Authentication "
                "failed", hostname, remuser, locuser, cmdbuf);
            exit(1);
        }

        if (checksum_required && !valid_checksum &&
            kcmd_protocol == KCMD_OLD_PROTOCOL) {
            syslog(LOG_WARNING, "Client did not supply required"
                    " checksum--connection rejected.");
            error("Client did not supply required"
                "checksum--connection rejected.\n");
            (void) audit_rshd_fail("Client did not supply required"
                " checksum--connection rejected.", hostname,
                remuser, locuser, cmdbuf);  /* BSM */
            goto signout;
        }

        /*
         * Authentication has succeeded, we now need
         * to check authorization.
         *
         * krb5_kuserok returns 1 if OK.
         */
        if (client && krb5_kuserok(bsd_context, client, locuser)) {
            auth_sent |= AUTH_KRB5;
        } else {
            syslog(LOG_ERR, "Principal %s (%s@%s) for local user "
                "%s failed krb5_kuserok.\n",
                kremuser, remuser, hostname, locuser);
        }
    } else {
        getstr(netf, remuser, sizeof (remuser), "remuser");
        getstr(netf, locuser, sizeof (locuser), "locuser");
        getstr(netf, cmdbuf, sizeof (cmdbuf), "command");
    }

#ifdef DEBUG
    syslog(LOG_NOTICE, "rshd: locuser = %s, remuser = %s, cmdbuf = %s",
            locuser, remuser, cmdbuf);
#endif /* DEBUG */

    /*
     * Note that there is no rsh conv functions at present.
     */
    if (krb5auth_flag > 0) {
        if ((err = pam_start("krsh", locuser, NULL, &pamh))
                != PAM_SUCCESS) {
            syslog(LOG_ERR, "pam_start() failed: %s\n",
                pam_strerror(0, err));
            exit(1);
        }
    }
    else
    {
        if ((err = pam_start("rsh", locuser, NULL, &pamh))
                != PAM_SUCCESS) {
            syslog(LOG_ERR, "pam_start() failed: %s\n",
                pam_strerror(0, err));
            exit(1);
        }
    }
    if ((err = pam_set_item(pamh, PAM_RHOST, hostname)) != PAM_SUCCESS) {
        syslog(LOG_ERR, "pam_set_item() failed: %s\n",
            pam_strerror(pamh, err));
        exit(1);
    }
    if ((err = pam_set_item(pamh, PAM_RUSER, remuser)) != PAM_SUCCESS) {
        syslog(LOG_ERR, "pam_set_item() failed: %s\n",
            pam_strerror(pamh, err));
        exit(1);
    }

    pwd = getpwnam(locuser);
    shpwd = getspnam(locuser);
    if ((pwd == NULL) || (shpwd == NULL)) {
        if (krb5auth_flag > 0)
            syslog(LOG_ERR, "Principal %s (%s@%s) for local user "
                "%s has no account.\n", kremuser, remuser,
                            hostname, locuser);
        error("permission denied.\n");
        (void) audit_rshd_fail("Login incorrect", hostname,
            remuser, locuser, cmdbuf);  /* BSM */
        exit(1);
    }

    if (krb5auth_flag > 0) {
        (void) snprintf(repository, sizeof (repository),
                    KRB5_REPOSITORY_NAME);
        /*
         * We currently only support special handling of the
         * KRB5 PAM repository
         */
        if (strlen(locuser) != 0) {
            krb5_repository_data_t krb5_data;
            pam_repository_t pam_rep_data;

            krb5_data.principal = locuser;
            krb5_data.flags = SUNW_PAM_KRB5_ALREADY_AUTHENTICATED;

            pam_rep_data.type = repository;
            pam_rep_data.scope = (void *)&krb5_data;
            pam_rep_data.scope_len = sizeof (krb5_data);

            (void) pam_set_item(pamh, PAM_REPOSITORY,
                    (void *)&pam_rep_data);
        }
    }

    if (shpwd->sp_pwdp != 0) {
        if (*shpwd->sp_pwdp != '\0') {
            if ((v = pam_authenticate(pamh, 0)) != PAM_SUCCESS) {
                error("permission denied\n");
                (void) audit_rshd_fail("Permission denied",
                    hostname, remuser, locuser, cmdbuf);
                (void) pam_end(pamh, v);
                exit(1);
            }
        } else {
            int flags;
            char *p;
            /*
             * maintain 2.1 and 4.* and BSD semantics with
             * anonymous rshd unless PASSREQ is set to YES in
             * /etc/default/login: then we deny logins with empty
             * passwords.
             */
            if (defopen(_PATH_DEFAULT_LOGIN) == 0) {
                flags = defcntl(DC_GETFLAGS, 0);
                TURNOFF(flags, DC_CASE);
                (void) defcntl(DC_SETFLAGS, flags);

                if ((p = defread("PASSREQ=")) != NULL &&
                    strcasecmp(p, "YES") == 0) {
                    error("permission denied\n");
                    (void) audit_rshd_fail(
                        "Permission denied", hostname,
                        remuser, locuser, cmdbuf);
                    (void) pam_end(pamh, PAM_ABORT);
                    (void) defopen(NULL);
                    syslog(LOG_AUTH|LOG_NOTICE,
                        "empty password not allowed for "
                        "%s from %s.", locuser, hostname);
                    exit(1);
                }
                (void) defopen(NULL);
            }
            /*
             * /etc/default/login not found or PASSREQ not set
             * to YES. Allow logins without passwords.
             */
        }
    }

    if (krb5auth_flag > 0) {
        if (require_encrypt && (!do_encrypt)) {
            error("You must use encryption.\n");
            (void) audit_rshd_fail("You must use encryption.",
                hostname, remuser, locuser, cmdbuf); /* BSM */
            goto signout;
        }

        if (!(auth_ok & auth_sent)) {
            if (auth_sent) {
                error("Another authentication mechanism "
                    "must be used to access this host.\n");
                (void) audit_rshd_fail("Another authentication"
                    " mechanism must be used to access"
                    " this host.\n", hostname, remuser,
                    locuser, cmdbuf); /* BSM */
                goto signout;
            } else {
                error("Permission denied.\n");
                (void) audit_rshd_fail("Permission denied.",
                    hostname, remuser, locuser, cmdbuf);
                    /* BSM */
                goto signout;
            }
        }


        if (pwd->pw_uid && !access("/etc/nologin", F_OK)) {
            error("Logins currently disabled.\n");
            (void) audit_rshd_fail("Logins currently disabled.",
                hostname, remuser, locuser, cmdbuf);
            goto signout;
        }

        /* Log access to account */
        if (pwd && (pwd->pw_uid == 0)) {
            syslog(LOG_NOTICE, "Executing %s for user %s (%s@%s)"
                " as ROOT", cmdbuf,
                kremuser, remuser, hostname);
        }
    }

    if ((v = pam_acct_mgmt(pamh, 0)) != PAM_SUCCESS) {
        switch (v) {
        case PAM_NEW_AUTHTOK_REQD:
            error("password expired\n");
            (void) audit_rshd_fail("Password expired", hostname,
                remuser, locuser, cmdbuf); /* BSM */
            break;
        case PAM_PERM_DENIED:
            error("account expired\n");
            (void) audit_rshd_fail("Account expired", hostname,
                remuser, locuser, cmdbuf); /* BSM */
            break;
        case PAM_AUTHTOK_EXPIRED:
            error("password expired\n");
            (void) audit_rshd_fail("Password expired", hostname,
                remuser, locuser, cmdbuf); /* BSM */
            break;
        default:
            error("login incorrect\n");
            (void) audit_rshd_fail("Permission denied", hostname,
                remuser, locuser, cmdbuf); /* BSM */
            break;
        }
        (void) pam_end(pamh, PAM_ABORT);
        exit(1);
    }

    if (chdir(pwd->pw_dir) < 0) {
        (void) chdir("/");
#ifdef notdef
        error("No remote directory.\n");

        exit(1);
#endif
    }

    /*
     * XXX There is no session management currently being done
     */

    (void) write(STDERR_FILENO, "\0", 1);
    if (port || do_encrypt) {
        if ((pipe(pv) < 0)) {
            error("Can't make pipe.\n");
            (void) pam_end(pamh, PAM_ABORT);
            exit(1);
        }
        if (do_encrypt) {
            if (pipe(pw) < 0) {
                error("Can't make pipe 2.\n");
                (void) pam_end(pamh, PAM_ABORT);
                exit(1);
            }
            if (pipe(px) < 0) {
                error("Can't make pipe 3.\n");
                (void) pam_end(pamh, PAM_ABORT);
                exit(1);
            }
        }
        pid = fork();
        if (pid == (pid_t)-1)  {
            error("Fork (to start shell) failed on server.  "
                "Please try again later.\n");
            (void) pam_end(pamh, PAM_ABORT);
            exit(1);
        }
        if (pid) {
            fd_set ready;
            fd_set readfrom;

            (void) close(STDIN_FILENO);
            (void) close(STDOUT_FILENO);
            (void) close(STDERR_FILENO);
            (void) close(pv[1]);
            if (do_encrypt) {
                (void) close(pw[1]);
                (void) close(px[0]);
            } else {
                (void) close(f);
            }

            (void) FD_ZERO(&readfrom);

            FD_SET(pv[0], &readfrom);
            if (do_encrypt) {
                FD_SET(pw[0], &readfrom);
                FD_SET(f, &readfrom);
            }
            if (port)
                FD_SET(s, &readfrom);

            /* read f (net), write to px[1] (child stdin) */
            /* read pw[0] (child stdout), write to f (net) */
            /* read s (alt. channel), signal child */
            /* read pv[0] (child stderr), write to s */
            if (ioctl(pv[0], FIONBIO, (char *)&one) == -1)
                syslog(LOG_INFO, "ioctl FIONBIO: %m");
            if (do_encrypt &&
                ioctl(pw[0], FIONBIO, (char *)&one) == -1)
                syslog(LOG_INFO, "ioctl FIONBIO: %m");
            do {
                ready = readfrom;
                if (select(FD_SETSIZE, &ready, NULL,
                    NULL, NULL) < 0) {
                    if (errno == EINTR) {
                        continue;
                    } else {
                        break;
                    }
                }
                /*
                 * Read from child stderr, write to net
                 */
                if (port && FD_ISSET(pv[0], &ready)) {
                    errno = 0;
                    cc = read(pv[0], buf, sizeof (buf));
                    if (cc <= 0) {
                        (void) shutdown(s, 2);
                        FD_CLR(pv[0], &readfrom);
                    } else {
                        (void) deswrite(s, buf, cc, 1);
                    }
                }
                /*
                 * Read from alternate channel, signal child
                 */
                if (port && FD_ISSET(s, &ready)) {
                    if ((int)desread(s, &sig, 1, 1) <= 0)
                        FD_CLR(s, &readfrom);
                    else
                        (void) killpg(pid, sig);
                }
                /*
                 * Read from child stdout, write to net
                 */
                if (do_encrypt && FD_ISSET(pw[0], &ready)) {
                    errno = 0;
                    cc = read(pw[0], buf, sizeof (buf));
                    if (cc <= 0) {
                        (void) shutdown(f, 2);
                        FD_CLR(pw[0], &readfrom);
                    } else {
                        (void) deswrite(f, buf, cc, 0);
                    }
                }
                /*
                 * Read from the net, write to child stdin
                 */
                if (do_encrypt && FD_ISSET(f, &ready)) {
                    errno = 0;
                    cc = desread(f, buf, sizeof (buf), 0);
                    if (cc <= 0) {
                        (void) close(px[1]);
                        FD_CLR(f, &readfrom);
                    } else {
                        int wcc;
                        wcc = write(px[1], buf, cc);
                        if (wcc == -1) {
                            /*
                             * pipe closed,
                             * don't read any
                             * more
                             *
                             * might check for
                             * EPIPE
                             */
                            (void) close(px[1]);
                            FD_CLR(f, &readfrom);
                        } else if (wcc != cc) {
                            /* CSTYLED */
                            syslog(LOG_INFO, gettext("only wrote %d/%d to child"),
                            wcc, cc);
                        }
                    }
                }
            } while ((port && FD_ISSET(s, &readfrom)) ||
                (port && FD_ISSET(pv[0], &readfrom)) ||
                (do_encrypt && FD_ISSET(f, &readfrom)) ||
                (do_encrypt && FD_ISSET(pw[0], &readfrom)));
#ifdef DEBUG
            syslog(LOG_INFO, "Shell process completed.");
#endif /* DEBUG */
            if (ccache)
                (void) pam_close_session(pamh, 0);
            (void) pam_end(pamh, PAM_SUCCESS);

            exit(0);
        } /* End of Parent block */

        (void) setsid();    /* Should be the same as above. */
        (void) close(pv[0]);
        (void) dup2(pv[1], 2);
        (void) close(pv[1]);
        if (port)
            (void) close(s);
        if (do_encrypt) {
            (void) close(f);
            (void) close(pw[0]);
            (void) close(px[1]);

            (void) dup2(px[0], 0);
            (void) dup2(pw[1], 1);

            (void) close(px[0]);
            (void) close(pw[1]);
        }
    }

    if (*pwd->pw_shell == '\0')
        pwd->pw_shell = "/bin/sh";
    if (!do_encrypt)
        (void) close(f);
    /*
     * write audit record before making uid switch
     */
    (void) audit_rshd_success(hostname, remuser, locuser, cmdbuf); /* BSM */

    /* set the real (and effective) GID */
    if (setgid(pwd->pw_gid) == -1) {
        error("Invalid gid.\n");
        (void) pam_end(pamh, PAM_ABORT);
        exit(1);
    }

    /*
     * Initialize the supplementary group access list.
     */
    if (strlen(locuser) == 0) {
        error("No local user.\n");
        (void) pam_end(pamh, PAM_ABORT);
        exit(1);
    }
    if (initgroups(locuser, pwd->pw_gid) == -1) {
        error("Initgroup failed.\n");
        (void) pam_end(pamh, PAM_ABORT);
        exit(1);
    }

    if ((v = pam_setcred(pamh, PAM_ESTABLISH_CRED)) != PAM_SUCCESS) {
        error("Insufficient credentials.\n");
        (void) pam_end(pamh, v);
        exit(1);
    }

    /* set the real (and effective) UID */
    if (setuid(pwd->pw_uid) == -1) {
        error("Invalid uid.\n");
        (void) pam_end(pamh, PAM_ABORT);
        exit(1);
    }

    /* Change directory only after becoming the appropriate user. */
    if (chdir(pwd->pw_dir) < 0) {
        (void) chdir("/");
        if (krb5auth_flag > 0) {
            syslog(LOG_ERR, "Principal %s  (%s@%s) for local user"
                " %s has no home directory.",
                kremuser, remuser, hostname, locuser);
            error("No remote directory.\n");
            goto signout;
        }
#ifdef notdef
        error("No remote directory.\n");
        exit(1);
#endif
    }

    path = (pwd->pw_uid == 0) ? rootpath : userpath;

    /*
     * Space for the following environment variables are dynamically
     * allocated because their lengths are not known before calling
     * getpwnam().
     */
    homedir_len = strlen(pwd->pw_dir) + strlen(homestr) + 1;
    shell_len = strlen(pwd->pw_shell) + strlen(shellstr) + 1;
    username_len = strlen(pwd->pw_name) + strlen(userstr) + 1;
    homedir = (char *)malloc(homedir_len);
    shell = (char *)malloc(shell_len);
    username = (char *)malloc(username_len);
    if (homedir == NULL || shell == NULL || username == NULL) {
        perror("malloc");
        exit(1);
    }
    (void) snprintf(homedir, homedir_len, "%s%s", homestr, pwd->pw_dir);
    (void) snprintf(shell, shell_len, "%s%s", shellstr, pwd->pw_shell);
    (void) snprintf(username, username_len, "%s%s", userstr, pwd->pw_name);

    /* Pass timezone to executed command. */
    if (tzenv = getenv("TZ")) {
        tz_len = strlen(tzenv) + strlen(tzstr) + 1;
        tz = malloc(tz_len);
        if (tz != NULL)
            (void) snprintf(tz, tz_len, "%s%s", tzstr, tzenv);
    }

    add_to_envinit(homedir);
    add_to_envinit(shell);
    add_to_envinit(path);
    add_to_envinit(username);
    add_to_envinit(tz);

    if (krb5auth_flag > 0) {
        int length;
        char *buffer;

        /*
         * If we have KRB5CCNAME set, then copy into the child's
         * environment.  This can't really have a fixed position
         * because `tz' may or may not be set.
         */
        if (getenv("KRB5CCNAME")) {
            length = (int)strlen(getenv("KRB5CCNAME")) +
                    (int)strlen("KRB5CCNAME=") + 1;
            buffer = (char *)malloc(length);

            if (buffer) {
                (void) snprintf(buffer, length, "KRB5CCNAME=%s",
                        getenv("KRB5CCNAME"));
                add_to_envinit(buffer);
            }
        } {
            /* These two are covered by ADDRPAD */
            length = strlen(inet_ntoa(localaddr.sin_addr)) + 1 +
                    strlen("KRB5LOCALADDR=");
            (void) snprintf(local_addr, length, "KRB5LOCALADDR=%s",
                inet_ntoa(localaddr.sin_addr));
            add_to_envinit(local_addr);

            length = strlen(inet_ntoa(sin->sin_addr)) + 1 +
                    strlen("KRB5REMOTEADDR=");
            (void) snprintf(remote_addr, length,
                "KRB5REMOTEADDR=%s", inet_ntoa(sin->sin_addr));
            add_to_envinit(remote_addr);
        }

        /*
         * If we do anything else, make sure there is
         * space in the array.
         */
        for (cnt = 0; cnt < num_env; cnt++) {
            char *buf;

            if (getenv(save_env[cnt])) {
                length = (int)strlen(getenv(save_env[cnt])) +
                    (int)strlen(save_env[cnt]) + 2;

                buf = (char *)malloc(length);
                if (buf) {
                    (void) snprintf(buf, length, "%s=%s",
                        save_env[cnt],
                        getenv(save_env[cnt]));
                    add_to_envinit(buf);
                }
            }
        }

    }

    /*
     * add PAM environment variables set by modules
     * -- only allowed 16 (PAM_ENV_ELIM)
     * -- check to see if the environment variable is legal
     */
    if ((pam_env = pam_getenvlist(pamh)) != 0) {
        while (pam_env[idx] != 0) {
            if (idx < PAM_ENV_ELIM &&
                legalenvvar(pam_env[idx])) {
                add_to_envinit(pam_env[idx]);
            }
            idx++;
        }
    }

    (void) pam_end(pamh, PAM_SUCCESS);

    /*
     * Pick up locale environment variables, if any.
     */
    lenvp = renvp;
    while (*lenvp != NULL) {
        int index;

        for (index = 0; localeenv[index] != NULL; index++)
            /*
             * locale_envmatch() returns 1 if
             * *lenvp is localenev[index] and valid.
             */
            if (locale_envmatch(localeenv[index], *lenvp)) {
                add_to_envinit(*lenvp);
                break;
            }

        lenvp++;
    }

    cp = strrchr(pwd->pw_shell, '/');
    if (cp != NULL)
        cp++;
    else
        cp = pwd->pw_shell;
    /*
     * rdist has been moved to /usr/bin, so /usr/ucb/rdist might not
     * be present on a system.  So if it doesn't exist we fall back
     * and try for it in /usr/bin.  We take care to match the space
     * after the name because the only purpose of this is to protect
     * the internal call from old rdist's, not humans who type
     * "rsh foo /usr/ucb/rdist".
     */
#define RDIST_PROG_NAME "/usr/ucb/rdist -Server"
    if (strncmp(cmdbuf, RDIST_PROG_NAME, strlen(RDIST_PROG_NAME)) == 0) {
        if (stat("/usr/ucb/rdist", &statb) != 0) {
            (void) strncpy(cmdbuf + 5, "bin", 3);
        }
    }

#ifdef DEBUG
    syslog(LOG_NOTICE, "rshd: cmdbuf = %s", cmdbuf);
    if (do_encrypt)
        syslog(LOG_NOTICE, "rshd: cmd to be exec'ed = %s",
            ((char *)cmdbuf + 3));
#endif /* DEBUG */

    if (do_encrypt && (strncmp(cmdbuf, "-x ", 3) == 0)) {
        (void) execle(pwd->pw_shell, cp, "-c", (char *)cmdbuf + 3,
                NULL, envinit);
    } else {
        (void) execle(pwd->pw_shell, cp, "-c", cmdbuf, NULL,
                envinit);
    }

    perror(pwd->pw_shell);
    exit(1);

signout:
    if (ccache)
        (void) pam_close_session(pamh, 0);
    ccache = NULL;
    (void) pam_end(pamh, PAM_ABORT);
    exit(1);
}

static void
getstr(fd, buf, cnt, err)
    int fd;
    char *buf;
    int cnt;
    char *err;
{
    char c;

    do {
        if (read(fd, &c, 1) != 1)
            exit(1);
        if (cnt-- == 0) {
            error("%s too long\n", err);
            exit(1);
        }
        *buf++ = c;
    } while (c != 0);
}

/*PRINTFLIKE1*/
static void
error(char *fmt, ...)
{
    va_list ap;
    char buf[RSHD_BUFSIZ];

    buf[0] = 1;
    va_start(ap, fmt);
    (void) vsnprintf(&buf[1], sizeof (buf) - 1, fmt, ap);
    va_end(ap);
    (void) write(STDERR_FILENO, buf, strlen(buf));
}

static char *illegal[] = {
    "SHELL=",
    "HOME=",
    "LOGNAME=",
#ifndef NO_MAIL
    "MAIL=",
#endif
    "CDPATH=",
    "IFS=",
    "PATH=",
    "USER=",
    "TZ=",
    0
};

/*
 * legalenvvar - can PAM modules insert this environmental variable?
 */

static int
legalenvvar(char *s)
{
    register char **p;

    for (p = illegal; *p; p++)
        if (strncmp(s, *p, strlen(*p)) == 0)
            return (0);

    if (s[0] == 'L' && s[1] == 'D' && s[2] == '_')
        return (0);

    return (1);
}

/*
 * Add a string to the environment of the new process.
 */

static void
add_to_envinit(char *string)
{
    /*
     * Reserve space for 2 * 8 = 16 environment entries initially which
     * should be enough to avoid reallocation of "envinit" in most cases.
     */
    static int  size = 8;
    static int  index = 0;

    if (string == NULL)
        return;

    if ((envinit == NULL) || (index == size)) {
        size *= 2;
        envinit = realloc(envinit, (size + 1) * sizeof (char *));
        if (envinit == NULL) {
            perror("malloc");
            exit(1);
        }
    }

    envinit[index++] = string;
    envinit[index] = NULL;
}

/*
 * Check if lenv and penv matches or not.
 */
static int
locale_envmatch(char *lenv, char *penv)
{
    while ((*lenv == *penv) && (*lenv != '\0') && (*penv != '=')) {
        lenv++;
        penv++;
    }

    /*
     * '/' is eliminated for security reason.
     */
    return ((*lenv == '\0' && *penv == '=' && *(penv + 1) != '/'));
}

#ifndef KRB_SENDAUTH_VLEN
#define KRB_SENDAUTH_VLEN   8   /* length for version strings */
#endif

/* MUST be KRB_SENDAUTH_VLEN chars */
#define KRB_SENDAUTH_VERS   "AUTHV0.1"
#define SIZEOF_INADDR sizeof (struct in_addr)

static krb5_error_code
recvauth(int netf, int *valid_checksum)
{
    krb5_auth_context auth_context = NULL;
    krb5_error_code status;
    struct sockaddr_in laddr;
    int len;
    krb5_data inbuf;
    krb5_authenticator *authenticator;
    krb5_ticket *ticket;
    krb5_rcache rcache;
    krb5_data version;
    krb5_encrypt_block eblock;  /* eblock for encrypt/decrypt */
    krb5_data desinbuf;
    krb5_data desoutbuf;
    char des_inbuf[2 * RSHD_BUFSIZ];
            /* needs to be > largest read size */
    char des_outbuf[2 * RSHD_BUFSIZ + 4];
            /* needs to be > largest write size */

    *valid_checksum = 0;
    len = sizeof (laddr);

    if (getsockname(netf, (struct sockaddr *)&laddr, &len)) {
        exit(1);
    }

    if (status = krb5_auth_con_init(bsd_context, &auth_context))
        return (status);

    if (status = krb5_auth_con_genaddrs(bsd_context, auth_context, netf,
        KRB5_AUTH_CONTEXT_GENERATE_REMOTE_FULL_ADDR))
        return (status);

    status = krb5_auth_con_getrcache(bsd_context, auth_context, &rcache);
    if (status)
        return (status);

    if (!rcache) {
        krb5_principal server;

        status = krb5_sname_to_principal(bsd_context, 0, 0,
            KRB5_NT_SRV_HST, &server);
        if (status)
            return (status);

        status = krb5_get_server_rcache(bsd_context,
            krb5_princ_component(bsd_context, server, 0),
            &rcache);
        krb5_free_principal(bsd_context, server);
        if (status)
            return (status);

        status = krb5_auth_con_setrcache(bsd_context, auth_context,
                            rcache);
        if (status)
            return (status);
    }

    status = krb5_recvauth_version(bsd_context, &auth_context, &netf,
        NULL,       /* Specify daemon principal */
        0,      /* no flags */
        keytab,     /* normally NULL to use v5srvtab */
        &ticket,    /* return ticket */
        &version);  /* application version string */


    if (status) {
        getstr(netf, locuser, sizeof (locuser), "locuser");
        getstr(netf, cmdbuf, sizeof (cmdbuf), "command");
        getstr(netf, remuser, sizeof (locuser), "remuser");
        return (status);
    }
    getstr(netf, locuser, sizeof (locuser), "locuser");
    getstr(netf, cmdbuf, sizeof (cmdbuf), "command");

    /* Must be V5  */

    kcmd_protocol = KCMD_UNKNOWN_PROTOCOL;
    if (version.length != 9 || version.data == NULL) {
        syslog(LOG_ERR, "bad application version length");
        error(gettext("bad application version length\n"));
        exit(1);
    }
    if (strncmp(version.data, "KCMDV0.1", 9) == 0) {
        kcmd_protocol = KCMD_OLD_PROTOCOL;
    } else if (strncmp(version.data, "KCMDV0.2", 9) == 0) {
        kcmd_protocol = KCMD_NEW_PROTOCOL;
    } else {
        syslog(LOG_ERR, "Unrecognized KCMD protocol (%s)",
            (char *)version.data);
        error(gettext("Unrecognized KCMD protocol (%s)"),
            (char *)version.data);
        exit(1);
    }
    getstr(netf, remuser, sizeof (locuser), "remuser");

    if ((status = krb5_unparse_name(bsd_context, ticket->enc_part2->client,
            &kremuser)))
        return (status);

    if ((status = krb5_copy_principal(bsd_context,
                ticket->enc_part2->client, &client)))
        return (status);


    if (checksum_required && (kcmd_protocol == KCMD_OLD_PROTOCOL)) {
        if ((status = krb5_auth_con_getauthenticator(bsd_context,
            auth_context, &authenticator)))
            return (status);

        if (authenticator->checksum && checksum_required) {
            struct sockaddr_in adr;
            int adr_length = sizeof (adr);
            int chksumsize = strlen(cmdbuf) + strlen(locuser) + 32;
            krb5_data input;
            krb5_keyblock key;

            char *chksumbuf = (char *)malloc(chksumsize);

            if (chksumbuf == 0)
                goto error_cleanup;
            if (getsockname(netf, (struct sockaddr *)&adr,
                    &adr_length) != 0)
                goto error_cleanup;

            (void) snprintf(chksumbuf, chksumsize, "%u:",
                    ntohs(adr.sin_port));
            if (strlcat(chksumbuf, cmdbuf,
                    chksumsize) >= chksumsize) {
                syslog(LOG_ERR, "cmd buffer too long.");
                free(chksumbuf);
                return (-1);
            }
            if (strlcat(chksumbuf, locuser,
                    chksumsize) >= chksumsize) {
                syslog(LOG_ERR, "locuser too long.");
                free(chksumbuf);
                return (-1);
            }

            input.data = chksumbuf;
            input.length = strlen(chksumbuf);
            key.magic = ticket->enc_part2->session->magic;
            key.enctype = ticket->enc_part2->session->enctype;
            key.contents = ticket->enc_part2->session->contents;
            key.length = ticket->enc_part2->session->length;

            status = krb5_c_verify_checksum(bsd_context,
                &key, 0, &input, authenticator->checksum,
                (unsigned int *)valid_checksum);

            if (status == 0 && *valid_checksum == 0)
                status = KRB5KRB_AP_ERR_BAD_INTEGRITY;
error_cleanup:
            if (chksumbuf)
                krb5_xfree(chksumbuf);
            if (status) {
                krb5_free_authenticator(bsd_context,
                        authenticator);
                return (status);
            }
        }
        krb5_free_authenticator(bsd_context, authenticator);
    }


    if ((strncmp(cmdbuf, "-x ", 3) == 0)) {
        if (krb5_privacy_allowed()) {
            do_encrypt = 1;
        } else {
            syslog(LOG_ERR, "rshd: Encryption not supported");
            error("rshd: Encryption not supported. \n");
            exit(2);
        }

        status = krb5_auth_con_getremotesubkey(bsd_context,
                            auth_context,
                            &sessionkey);
        if (status) {
            syslog(LOG_ERR, "Error getting KRB5 session subkey");
            error(gettext("Error getting KRB5 session subkey"));
            exit(1);
        }
        /*
         * The "new" protocol requires that a subkey be sent.
         */
        if (sessionkey == NULL && kcmd_protocol == KCMD_NEW_PROTOCOL) {
            syslog(LOG_ERR, "No KRB5 session subkey sent");
            error(gettext("No KRB5 session subkey sent"));
            exit(1);
        }
        /*
         * The "old" protocol does not permit an authenticator subkey.
         * The key is taken from the ticket instead (see below).
         */
        if (sessionkey != NULL && kcmd_protocol == KCMD_OLD_PROTOCOL) {
            syslog(LOG_ERR, "KRB5 session subkey not permitted "
                "with old KCMD protocol");
            error(gettext("KRB5 session subkey not permitted "
                "with old KCMD protocol"));
            exit(1);
        }
        /*
         * If no key at this point, use the session key from
         * the ticket.
         */
        if (sessionkey == NULL) {
            /*
             * Save the session key so we can configure the crypto
             * module later.
             */
            status = krb5_copy_keyblock(bsd_context,
                        ticket->enc_part2->session,
                        &sessionkey);
            if (status) {
                syslog(LOG_ERR, "krb5_copy_keyblock failed");
                error(gettext("krb5_copy_keyblock failed"));
                exit(1);
            }
        }
        /*
         * If session key still cannot be found, we must
         * exit because encryption is required here
         * when encr_flag (-x) is set.
         */
        if (sessionkey == NULL) {
            syslog(LOG_ERR, "Could not find an encryption key");
            error(gettext("Could not find an encryption key"));
            exit(1);
        }

        /*
         * Initialize parameters/buffers for desread & deswrite here.
         */
        desinbuf.data = des_inbuf;
        desoutbuf.data = des_outbuf;
        desinbuf.length = sizeof (des_inbuf);
        desoutbuf.length = sizeof (des_outbuf);

        eblock.crypto_entry = sessionkey->enctype;
        eblock.key = (krb5_keyblock *)sessionkey;

        init_encrypt(do_encrypt, bsd_context, kcmd_protocol,
                &desinbuf, &desoutbuf, SERVER, &eblock);
    }

    ticket->enc_part2->session = 0;

    if ((status = krb5_read_message(bsd_context, (krb5_pointer) & netf,
                &inbuf))) {
        error(gettext("Error reading message: %s\n"),
                error_message(status));
        exit(1);
    }

    if (inbuf.length) {
        krb5_creds **creds = NULL;

        /* Forwarding being done, read creds */
        if ((status = krb5_rd_cred(bsd_context,
                        auth_context, &inbuf, &creds,
                        NULL))) {
            error("Can't get forwarded credentials: %s\n",
                error_message(status));
            exit(1);
        }

        /* Store the forwarded creds in the ccache */
        if ((status = store_forw_creds(bsd_context,
                        creds, ticket, locuser,
                        &ccache))) {
            error("Can't store forwarded credentials: %s\n",
                error_message(status));
            exit(1);
        }
        krb5_free_creds(bsd_context, *creds);
    }

    krb5_free_ticket(bsd_context, ticket);
    return (0);
}

static void
usage(void)
{
    (void) fprintf(stderr, gettext("%s: rshd [-k5eciU] "
            "[-P path] [-M realm] [-s tos] "
#ifdef DEBUG
            "[-D port] "
#endif /* DEBUG */
            "[-S keytab]"), gettext("usage"));

    syslog(LOG_ERR, "%s: rshd [-k5eciU] [-P path] [-M realm] [-s tos] "
#ifdef DEBUG
            "[-D port] "
#endif /* DEBUG */
            "[-S keytab]", gettext("usage"));
}