usr/src/lib/libtelnet/kerberos5.c

/*-
 * Copyright (c) 1991 The Regents of the University of California.
 * All rights reserved.
 *
 * %sccs.include.redist.c%
 */

#ifndef lint
static char sccsid[] = "@(#)kerberos5.c 5.1 (Berkeley) %G%";
#endif /* not lint */

/*
 * Copyright (C) 1990 by the Massachusetts Institute of Technology
 *
 * Export of this software from the United States of America is assumed
 * to require a specific license from the United States Government.
 * It is the responsibility of any person or organization contemplating
 * export to obtain such a license before exporting.
 *
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of M.I.T. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 */


#ifdef  KRB5
#include <arpa/telnet.h>
#include <stdio.h>
#include <krb5/krb5.h>
#include <krb5/crc-32.h>
#include <krb5/libos-proto.h>
#include <netdb.h>
#include <ctype.h>

#ifdef  __STDC__
#include <stdlib.h>
#endif
#ifdef  NO_STRING_H
#include <strings.h>
#else
#include <string.h>
#endif

#include "encrypt.h"
#include "auth.h"
#include "misc.h"

extern auth_debug_mode;

char *malloc();

static unsigned char str_data[1024] = { IAC, SB, TELOPT_AUTHENTICATION, 0,
                                        AUTHTYPE_KERBEROS_V5, };

#define KRB_AUTH        0               /* Authentication data follows */
#define KRB_REJECT      1               /* Rejected (reason might follow) */
#define KRB_ACCEPT      2               /* Accepted (name might follow) */
#define KRB_NEWKEY      3               /* New key to use */
#define KRB_NAME        4               /* Name to authenticate for */

static  krb5_data auth;
        /* telnetd gets session key from here */
static  krb5_tkt_authent *authdat = NULL;

#if     defined(ENCRYPT)
Block   session_key;
#endif

        static int
Data(type, d, c)
        int type;
        void *d;
        int c;
{
        unsigned char *p = str_data + 6;
        unsigned char *cd = (unsigned char *)d;

        if (c == -1)
                c = strlen(d);

        if (auth_debug_mode) {
                printf("%s:%d: [%d] (%d)",
                        str_data[3] == TELQUAL_IS ? ">>>IS" : ">>>REPLY",
                        str_data[3],
                        type, c);
                printd(d, c);
                printf("\r\n");
        }
        *p++ = type;
        while (c-- > 0) {
                if ((*p++ = *cd++) == IAC)
                        *p++ = IAC;
        }
        *p++ = IAC;
        *p++ = SE;
        if (str_data[3] == TELQUAL_IS)
                printsub('>', &str_data[2], p - &str_data[2]);
        return(net_write(str_data, p - str_data));
}

        int
kerberos5_init(ap, server)
        Authenticator *ap;
        int server;
{
        if (server)
                str_data[3] = TELQUAL_REPLY;
        else
                str_data[3] = TELQUAL_IS;
        str_data[4] = ap->type;
        str_data[5] = ap->way;
        krb5_init_ets();
        return(1);
}

        int
kerberos5_send(ap)
        Authenticator *ap;
{
        char **realms;
        char *name;
        char *p1, *p2;
        krb5_checksum ksum;
        krb5_octet sum[CRC32_CKSUM_LENGTH];
        krb5_data *server[4];
        krb5_data srvdata[3];
        krb5_error_code r;
        krb5_ccache ccache;
        krb5_creds creds;               /* telnet gets session key from here */
        extern krb5_flags krb5_kdc_default_options;

        ksum.checksum_type = CKSUMTYPE_CRC32;
        ksum.contents = sum;
        ksum.length = sizeof(sum);
        bzero((void *)sum, sizeof(sum));

        if (!UserNameRequested) {
                if (auth_debug_mode) {
                        printf("Kerberos V5: no user name supplied\r\n");
                }
                return(0);
        }

        if (r = krb5_cc_default(&ccache)) {
                if (auth_debug_mode) {
                        printf("Kerberos V5: could not get default ccache\r\n");
                }
                return(0);
        }

        if ((name = malloc(strlen(RemoteHostName)+1)) == NULL) {
                if (auth_debug_mode)
                        printf("Out of memory for hostname in Kerberos V5\r\n");
                return(0);
        }

        if (r = krb5_get_host_realm(RemoteHostName, &realms)) {
                if (auth_debug_mode)
                        printf("Kerberos V5: no realm for %s\r\n", RemoteHostName);
                free(name);
                return(0);
        }

        p1 = RemoteHostName;
        p2 = name;

        while (*p2 = *p1++) {
                if (isupper(*p2))
                        *p2 |= 040;
                ++p2;
        }

        srvdata[0].data = realms[0];
        srvdata[0].length = strlen(realms[0]);
        srvdata[1].data = "rcmd";
        srvdata[1].length = 4;
        srvdata[2].data = name;
        srvdata[2].length = p2 - name;

        server[0] = &srvdata[0];
        server[1] = &srvdata[1];
        server[2] = &srvdata[2];
        server[3] = 0;

        bzero((char *)&creds, sizeof(creds));
        creds.server = (krb5_principal)server;

        if (r = krb5_cc_get_principal(ccache, &creds.client)) {
                if (auth_debug_mode) {
                        printf("Keberos V5: failure on principal (%d)\r\n",
                                error_message(r));
                }
                free(name);
                krb5_free_host_realm(realms);
                return(0);
        }

        if (r = krb5_get_credentials(krb5_kdc_default_options, ccache, &creds)) {
                if (auth_debug_mode) {
                        printf("Keberos V5: failure on credentials(%d)\r\n",r);
                }
                free(name);
                krb5_free_host_realm(realms);
                return(0);
        }

        r = krb5_mk_req_extended(0, &ksum, &creds.times,
                                 krb5_kdc_default_options,
                                 ccache, &creds, 0, &auth);

        free(name);
        krb5_free_host_realm(realms);
        if (r) {
                if (auth_debug_mode) {
                        printf("Keberos V5: mk_req failed\r\n");
                }
                return(0);
        }

        if (!Data(KRB_NAME, (void *)UserNameRequested, -1)) {
                if (auth_debug_mode)
                        printf("Not enough room for user name\r\n");
                return(0);
        }
        if (!Data(KRB_AUTH, auth.data, auth.length)) {
                if (auth_debug_mode)
                        printf("Not enough room for authentication data\r\n");
                return(0);
        }
#if     defined(ENCRYPT)
        if (creds.keyblock.keytype == KEYTYPE_DES) {
                Schedule krb_sched;
                Block enckey;

                des_key_sched(creds.keyblock.contents, krb_sched);
                des_set_random_generator_seed(creds.keyblock.contents);
                des_new_random_key(session_key);
                des_ecb_encrypt(session_key, enckey, krb_sched, 1);
                Data(KRB_NEWKEY, (void *)enckey, sizeof(enckey));
        }
#endif
        if (auth_debug_mode) {
                printf("Sent Kerberos V5 credentials to server\r\n");
        }
        return(1);
}

        void
kerberos5_is(ap, data, cnt)
        Authenticator *ap;
        unsigned char *data;
        int cnt;
{
        int r;
        struct hostent *hp;
        char *p1, *p2;
        static char *realm = NULL;
        krb5_data *server[4];
        krb5_data srvdata[3];
        Schedule sched;
        Session_Key skey;
        char *name;
        char *getenv();

        if (cnt-- < 1)
                return;
        switch (*data++) {
        case KRB_NAME: {
                char user[256];

                if (cnt > 255)
                        cnt = 255;
                strncpy(user, data, cnt);
                user[cnt] = 0;
                auth_encrypt_user(user);
                return;
            }
        case KRB_AUTH:
                auth.data = (char *)data;
                auth.length = cnt;

                if (!(hp = gethostbyname(LocalHostName))) {
                        if (auth_debug_mode)
                                printf("Cannot resolve local host name\r\n");
                        Data(KRB_REJECT, "Unknown local hostname.", -1);
                        auth_finished(ap, AUTH_REJECT);
                        return;
                }

                if (!realm && (krb5_get_default_realm(&realm))) {
                        if (auth_debug_mode)
                                printf("Could not get defualt realm\r\n");
                        Data(KRB_REJECT, "Could not get default realm.", -1);
                        auth_finished(ap, AUTH_REJECT);
                        return;
                }

                if ((name = malloc(strlen(hp->h_name)+1)) == NULL) {
                        if (auth_debug_mode)
                                printf("Out of memory for hostname in Kerberos V5\r\n");
                        Data(KRB_REJECT, "Out of memory.", -1);
                        auth_finished(ap, AUTH_REJECT);
                        return;
                }

                p1 = hp->h_name;
                p2 = name;

                while (*p2 = *p1++) {
                        if (isupper(*p2))
                                *p2 |= 040;
                        ++p2;
                }

                srvdata[0].data = realm;
                srvdata[0].length = strlen(realm);
                srvdata[1].data = "rcmd";
                srvdata[1].length = 4;
                srvdata[2].data = name;
                srvdata[2].length = p2 - name;

                server[0] = &srvdata[0];
                server[1] = &srvdata[1];
                server[2] = &srvdata[2];
                server[3] = 0;

                if (authdat)
                        krb5_free_tkt_authent(authdat);
                if (r = krb5_rd_req_simple(&auth, server, 0, &authdat)) {
                        char errbuf[128];

                        authdat = 0;
                        (void) strcpy(errbuf, "Read req failed: ");
                        (void) strcat(errbuf, error_message(r));
                        Data(KRB_REJECT, errbuf, -1);
                        if (auth_debug_mode)
                                printf("%s\r\n", errbuf);
                        return;
                }
                free(name);
                if (krb5_unparse_name(authdat->ticket->enc_part2 ->client,
                                                                        &name))
                        name = 0;
                Data(KRB_ACCEPT, name, name ? -1 : 0);
                if (auth_debug_mode) {
                        printf("Kerberos5 accepting him as ``%s''\r\n",
                                                        name ? name : "");
                }
                auth_finished(ap, AUTH_USER);
                return;
        case KRB_NEWKEY:
#if     defined(ENCRYPT)
                if (authdat && authdat->ticket->enc_part2->session->keytype
                                == KEYTYPE_DES)
                {
                        des_key_sched(authdat->ticket->enc_part2->session
                                                        ->contents, sched);
                        des_ecb_encrypt(data, session_key, sched, 0);
                        skey.type = SK_DES;
                        skey.length = 8;
                        skey.data = session_key;
                        encrypt_session_key(&skey, 1);
                }
#endif
                return;
        default:
                if (auth_debug_mode)
                        printf("Unknown Kerberos option %d\r\n", data[-1]);
                Data(KRB_REJECT, 0, 0);
                return;
        }
}

        void
kerberos5_reply(ap, data, cnt)
        Authenticator *ap;
        unsigned char *data;
        int cnt;
{
        Session_Key skey;

        if (cnt-- < 1)
                return;
        switch (*data++) {
        case KRB_REJECT:
                if (cnt > 0) {
                        printf("[ Kerberos V5 refuses authentication because %.*s ]\r\n",
                                cnt, data);
                } else
                        printf("[ Kerberos V5 refuses authentication ]\r\n");
                auth_send_retry();
                return;
        case KRB_ACCEPT:
                if (cnt > 0) {
                        printf("[ Kerberos V5 accepts you as %.*s ]\n", cnt, data);
                } else
                        printf("[ Kerberos V5 accepts you ]\n", cnt, data);
#if     defined(ENCRYPT)
                skey.type = SK_DES;
                skey.length = 8;
                skey.data = session_key;
                encrypt_session_key(&skey, 0);
#endif
                auth_finished(ap, AUTH_USER);
                return;
        default:
                if (auth_debug_mode)
                        printf("Unknown Kerberos option %d\r\n", data[-1]);
                return;
        }
}

        int
kerberos5_status(ap, name, level)
        Authenticator *ap;
        char *name;
        int level;
{
        if (level < AUTH_USER)
                return(level);

        if (UserNameRequested &&
            krb5_kuserok(authdat->ticket->enc_part2->client, UserNameRequested))
        {
                strcpy(name, UserNameRequested);
                return(AUTH_VALID);
        } else
                return(AUTH_USER);
}

#define BUMP(buf, len)          while (*(buf)) {++(buf), --(len);}
#define ADDC(buf, len, c)       if ((len) > 0) {*(buf)++ = (c); --(len));}

        void
kerberos5_printsub(data, cnt, buf, buflen)
        unsigned char *data, *buf;
        int cnt, buflen;
{
        char lbuf[32];
        register int i;

        buf[buflen-1] = '\0';           /* make sure its NULL terminated */
        buflen -= 1;

        switch(data[3]) {
        case KRB_NAME:                  /* Name to authenticate for */
                strncpy(buf, " NAME ", buflen);
                goto common;

        case KRB_REJECT:                /* Rejected (reason might follow) */
                strncpy(buf, " REJECT ", buflen);
                goto common;

        case KRB_ACCEPT:                /* Accepted (name might follow) */
                strncpy(buf, " ACCEPT ", buflen);
        common:
                BUMP(buf, buflen);
                if (cnt <= 4)
                        break;
                ADDC(buf, buflen, '"');
                for (i = 4; i < cnt; i++)
                        ADDC(buf, buflen, data[i]);
                ADDC(buf, buflen, '"');
                ADDC(buf, buflen, '\0');
                break;

        case KRB_AUTH:                  /* Authentication data follows */
                strncpy(buf, " AUTH", buflen);
                goto common2;

        case KRB_NEWKEY:                /* A new session key follows */
                strncpy(buf, " NEWKEY", buflen);
                goto common2;

        default:
                sprintf(lbuf, " %d (unknown)", data[3]);
                strncpy(buf, lbuf, buflen);
        common2:
                BUMP(buf, buflen);
                for (i = 4; i < cnt; i++) {
                        sprintf(lbuf, " %d", data[i]);
                        strncpy(buf, lbuf, buflen);
                        BUMP(buf, buflen);
                }
                break;
        }
}
#endif