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telnetd/libtelnet/kerberos5.c

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/*
* $Source: /mit/krb5/.cvsroot/src/appl/telnet/libtelnet/kerberos5.c,v $
* $Author: tytso $
* $Id: kerberos5.c,v 1.1 1997/09/04 06:11:15 markm Exp $
*/
#if !defined(lint) && !defined(SABER)
static
#ifdef __STDC__
const
#endif
char rcsid_kerberos5_c[] = "$Id: kerberos5.c,v 1.1 1997/09/04 06:11:15 markm Exp $";
#endif /* lint */
/*-
* Copyright (c) 1991, 1993
* 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[] = "@(#)kerberos5.c 8.3 (Berkeley) 5/30/95";
#endif /* not lint */
/*
* Copyright (C) 1990 by the Massachusetts Institute of Technology
*
* Export of this software from the United States of America may
* 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/asn1.h>
#include <krb5/crc-32.h>
#include <krb5/los-proto.h>
#include <krb5/ext-proto.h>
#include <com_err.h>
#include <netdb.h>
#include <ctype.h>
/* kerberos 5 include files (ext-proto.h) will get an appropriate stdlib.h
and string.h/strings.h */
#include "encrypt.h"
#include "auth.h"
#include "misc.h"
extern auth_debug_mode;
#ifdef FORWARD
int forward_flags = 0; /* Flags get set in telnet/main.c on -f and -F */
/* These values need to be the same as those defined in telnet/main.c. */
/* Either define them in both places, or put in some common header file. */
#define OPTS_FORWARD_CREDS 0x00000002
#define OPTS_FORWARDABLE_CREDS 0x00000001
void kerberos5_forward();
#endif /* FORWARD */
static unsigned char str_data[1024] = { IAC, SB, TELOPT_AUTHENTICATION, 0,
AUTHTYPE_KERBEROS_V5, };
/*static unsigned char str_name[1024] = { IAC, SB, TELOPT_AUTHENTICATION,
TELQUAL_NAME, };*/
#define KRB_AUTH 0 /* Authentication data follows */
#define KRB_REJECT 1 /* Rejected (reason might follow) */
#define KRB_ACCEPT 2 /* Accepted */
#define KRB_RESPONSE 3 /* Response for mutual auth. */
#ifdef FORWARD
#define KRB_FORWARD 4 /* Forwarded credentials follow */
#define KRB_FORWARD_ACCEPT 5 /* Forwarded credentials accepted */
#define KRB_FORWARD_REJECT 6 /* Forwarded credentials rejected */
#endif /* FORWARD */
static krb5_data auth;
/* telnetd gets session key from here */
static krb5_tkt_authent *authdat = NULL;
/* telnet matches the AP_REQ and AP_REP with this */
static krb5_authenticator authenticator;
/* some compilers can't hack void *, so we use the Kerberos krb5_pointer,
which is either void * or char *, depending on the compiler. */
#define Voidptr krb5_pointer
Block session_key;
static int
Data(ap, type, d, c)
Authenticator *ap;
int type;
Voidptr d;
int c;
{
unsigned char *p = str_data + 4;
unsigned char *cd = (unsigned char *)d;
if (c == -1)
c = strlen((char *)cd);
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++ = ap->type;
*p++ = ap->way;
*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;
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_principal server;
krb5_error_code r;
krb5_ccache ccache;
krb5_creds creds; /* telnet gets session key from here */
extern krb5_flags krb5_kdc_default_options;
int ap_opts;
#ifdef ENCRYPTION
krb5_keyblock *newkey = 0;
#endif /* ENCRYPTION */
ksum.checksum_type = CKSUMTYPE_CRC32;
ksum.contents = sum;
ksum.length = sizeof(sum);
memset((Voidptr )sum, 0, 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;
}
if (r = krb5_build_principal_ext(&server,
strlen(realms[0]), realms[0],
4, "host",
p2 - name, name,
0)) {
if (auth_debug_mode) {
printf("Kerberos V5: failure setting up principal (%s)\r\n",
error_message(r));
}
free(name);
krb5_free_host_realm(realms);
return(0);
}
memset((char *)&creds, 0, sizeof(creds));
creds.server = server;
if (r = krb5_cc_get_principal(ccache, &creds.client)) {
if (auth_debug_mode) {
printf("Kerberos V5: failure on principal (%s)\r\n",
error_message(r));
}
free(name);
krb5_free_principal(server);
krb5_free_host_realm(realms);
return(0);
}
if (r = krb5_get_credentials(krb5_kdc_default_options, ccache, &creds)) {
if (auth_debug_mode) {
printf("Kerberos V5: failure on credentials(%d)\r\n",r);
}
free(name);
krb5_free_host_realm(realms);
krb5_free_principal(server);
return(0);
}
if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL)
ap_opts = AP_OPTS_MUTUAL_REQUIRED;
else
ap_opts = 0;
r = krb5_mk_req_extended(ap_opts, &ksum, krb5_kdc_default_options, 0,
#ifdef ENCRYPTION
&newkey,
#else /* ENCRYPTION */
0,
#endif /* ENCRYPTION */
ccache, &creds, &authenticator, &auth);
/* don't let the key get freed if we clean up the authenticator */
authenticator.subkey = 0;
free(name);
krb5_free_host_realm(realms);
krb5_free_principal(server);
#ifdef ENCRYPTION
if (newkey) {
/* keep the key in our private storage, but don't use it
yet---see kerberos5_reply() below */
if (newkey->keytype != KEYTYPE_DES) {
if (creds.keyblock.keytype == KEYTYPE_DES)
/* use the session key in credentials instead */
memmove((char *)session_key,
(char *)creds.keyblock.contents, sizeof(Block));
else
/* XXX ? */;
} else {
memmove((char *)session_key, (char *)newkey->contents,
sizeof(Block));
}
krb5_free_keyblock(newkey);
}
#endif /* ENCRYPTION */
if (r) {
if (auth_debug_mode) {
printf("Kerberos V5: mk_req failed (%s)\r\n",
error_message(r));
}
return(0);
}
if (!auth_sendname(UserNameRequested, strlen(UserNameRequested))) {
if (auth_debug_mode)
printf("Not enough room for user name\r\n");
return(0);
}
if (!Data(ap, KRB_AUTH, auth.data, auth.length)) {
if (auth_debug_mode)
printf("Not enough room for authentication data\r\n");
return(0);
}
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_principal server;
krb5_ap_rep_enc_part reply;
krb5_data outbuf;
#ifdef ENCRYPTION
Session_Key skey;
#endif /* ENCRYPTION */
char *name;
char *getenv();
krb5_data inbuf;
if (cnt-- < 1)
return;
switch (*data++) {
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(ap, 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 default realm\r\n");
Data(ap, 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(ap, 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;
}
if (authdat)
krb5_free_tkt_authent(authdat);
r = krb5_build_principal_ext(&server,
strlen(realm), realm,
4, "host",
p2 - name, name,
0);
if (!r) {
r = krb5_rd_req_simple(&auth, server, 0, &authdat);
krb5_free_principal(server);
}
if (r) {
char errbuf[128];
errout:
authdat = 0;
(void) strcpy(errbuf, "Read req failed: ");
(void) strcat(errbuf, error_message(r));
Data(ap, KRB_REJECT, errbuf, -1);
if (auth_debug_mode)
printf("%s\r\n", errbuf);
return;
}
free(name);
if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) {
/* do ap_rep stuff here */
reply.ctime = authdat->authenticator->ctime;
reply.cusec = authdat->authenticator->cusec;
reply.subkey = 0; /* use the one he gave us, so don't
need to return one here */
reply.seq_number = 0; /* we don't do seq #'s. */
if (r = krb5_mk_rep(&reply,
authdat->authenticator->subkey ?
authdat->authenticator->subkey :
authdat->ticket->enc_part2->session,
&outbuf)) {
goto errout;
}
Data(ap, KRB_RESPONSE, outbuf.data, outbuf.length);
}
if (krb5_unparse_name(authdat->ticket->enc_part2 ->client,
&name))
name = 0;
Data(ap, KRB_ACCEPT, name, name ? -1 : 0);
if (auth_debug_mode) {
printf("Kerberos5 identifies him as ``%s''\r\n",
name ? name : "");
}
auth_finished(ap, AUTH_USER);
free(name);
if (authdat->authenticator->subkey &&
authdat->authenticator->subkey->keytype == KEYTYPE_DES) {
memmove((Voidptr )session_key,
(Voidptr )authdat->authenticator->subkey->contents,
sizeof(Block));
} else if (authdat->ticket->enc_part2->session->keytype ==
KEYTYPE_DES) {
memmove((Voidptr )session_key,
(Voidptr )authdat->ticket->enc_part2->session->contents,
sizeof(Block));
} else
break;
#ifdef ENCRYPTION
skey.type = SK_DES;
skey.length = 8;
skey.data = session_key;
encrypt_session_key(&skey, 1);
#endif /* ENCRYPTION */
break;
#ifdef FORWARD
case KRB_FORWARD:
inbuf.data = (char *)data;
inbuf.length = cnt;
if (r = rd_and_store_for_creds(&inbuf, authdat->ticket,
UserNameRequested)) {
char errbuf[128];
(void) strcpy(errbuf, "Read forwarded creds failed: ");
(void) strcat(errbuf, error_message(r));
Data(ap, KRB_FORWARD_REJECT, errbuf, -1);
if (auth_debug_mode)
printf("Could not read forwarded credentials\r\n");
}
else
Data(ap, KRB_FORWARD_ACCEPT, 0, 0);
if (auth_debug_mode)
printf("Forwarded credentials obtained\r\n");
break;
#endif /* FORWARD */
default:
if (auth_debug_mode)
printf("Unknown Kerberos option %d\r\n", data[-1]);
Data(ap, KRB_REJECT, 0, 0);
break;
}
}
void
kerberos5_reply(ap, data, cnt)
Authenticator *ap;
unsigned char *data;
int cnt;
{
Session_Key skey;
static int mutual_complete = 0;
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 ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL &&
!mutual_complete) {
printf("[ Kerberos V5 accepted you, but didn't provide mutual authentication! ]\n");
auth_send_retry();
return;
}
if (cnt)
printf("[ Kerberos V5 accepts you as ``%.*s'' ]\n", cnt, data);
else
printf("[ Kerberos V5 accepts you ]\n");
auth_finished(ap, AUTH_USER);
#ifdef FORWARD
if (forward_flags & OPTS_FORWARD_CREDS)
kerberos5_forward(ap);
#endif /* FORWARD */
break;
case KRB_RESPONSE:
if ((ap->way & AUTH_HOW_MASK) == AUTH_HOW_MUTUAL) {
/* the rest of the reply should contain a krb_ap_rep */
krb5_ap_rep_enc_part *reply;
krb5_data inbuf;
krb5_error_code r;
krb5_keyblock tmpkey;
inbuf.length = cnt;
inbuf.data = (char *)data;
tmpkey.keytype = KEYTYPE_DES;
tmpkey.contents = session_key;
tmpkey.length = sizeof(Block);
if (r = krb5_rd_rep(&inbuf, &tmpkey, &reply)) {
printf("[ Mutual authentication failed: %s ]\n",
error_message(r));
auth_send_retry();
return;
}
if (reply->ctime != authenticator.ctime ||
reply->cusec != authenticator.cusec) {
printf("[ Mutual authentication failed (mismatched KRB_AP_REP) ]\n");
auth_send_retry();
return;
}
krb5_free_ap_rep_enc_part(reply);
#ifdef ENCRYPTION
skey.type = SK_DES;
skey.length = 8;
skey.data = session_key;
encrypt_session_key(&skey, 0);
#endif /* ENCRYPTION */
mutual_complete = 1;
}
return;
#ifdef FORWARD
case KRB_FORWARD_ACCEPT:
printf("[ Kerberos V5 accepted forwarded credentials ]\n");
return;
case KRB_FORWARD_REJECT:
printf("[ Kerberos V5 refuses forwarded credentials because %.*s ]\r\n",
cnt, data);
return;
#endif /* FORWARD */
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_REJECT: /* Rejected (reason might follow) */
strncpy((char *)buf, " REJECT ", buflen);
goto common;
case KRB_ACCEPT: /* Accepted (name might follow) */
strncpy((char *)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((char *)buf, " AUTH", buflen);
goto common2;
case KRB_RESPONSE:
strncpy((char *)buf, " RESPONSE", buflen);
goto common2;
#ifdef FORWARD
case KRB_FORWARD: /* Forwarded credentials follow */
strncpy((char *)buf, " FORWARD", buflen);
goto common2;
case KRB_FORWARD_ACCEPT: /* Forwarded credentials accepted */
strncpy((char *)buf, " FORWARD_ACCEPT", buflen);
goto common2;
case KRB_FORWARD_REJECT: /* Forwarded credentials rejected */
/* (reason might follow) */
strncpy((char *)buf, " FORWARD_REJECT", buflen);
goto common2;
#endif /* FORWARD */
default:
sprintf(lbuf, " %d (unknown)", data[3]);
strncpy((char *)buf, lbuf, buflen);
common2:
BUMP(buf, buflen);
for (i = 4; i < cnt; i++) {
sprintf(lbuf, " %d", data[i]);
strncpy((char *)buf, lbuf, buflen);
BUMP(buf, buflen);
}
break;
}
}
#ifdef FORWARD
void
kerberos5_forward(ap)
Authenticator *ap;
{
struct hostent *hp;
krb5_creds *local_creds;
krb5_error_code r;
krb5_data forw_creds;
extern krb5_cksumtype krb5_kdc_req_sumtype;
krb5_ccache ccache;
int i;
if (!(local_creds = (krb5_creds *)
calloc(1, sizeof(*local_creds)))) {
if (auth_debug_mode)
printf("Kerberos V5: could not allocate memory for credentials\r\n");
return;
}
if (r = krb5_sname_to_principal(RemoteHostName, "host", 1,
&local_creds->server)) {
if (auth_debug_mode)
printf("Kerberos V5: could not build server name - %s\r\n",
error_message(r));
krb5_free_creds(local_creds);
return;
}
if (r = krb5_cc_default(&ccache)) {
if (auth_debug_mode)
printf("Kerberos V5: could not get default ccache - %s\r\n",
error_message(r));
krb5_free_creds(local_creds);
return;
}
if (r = krb5_cc_get_principal(ccache, &local_creds->client)) {
if (auth_debug_mode)
printf("Kerberos V5: could not get default principal - %s\r\n",
error_message(r));
krb5_free_creds(local_creds);
return;
}
/* Get ticket from credentials cache */
if (r = krb5_get_credentials(KRB5_GC_CACHED, ccache, local_creds)) {
if (auth_debug_mode)
printf("Kerberos V5: could not obtain credentials - %s\r\n",
error_message(r));
krb5_free_creds(local_creds);
return;
}
if (r = get_for_creds(ETYPE_DES_CBC_CRC,
krb5_kdc_req_sumtype,
RemoteHostName,
local_creds->client,
&local_creds->keyblock,
forward_flags & OPTS_FORWARDABLE_CREDS,
&forw_creds)) {
if (auth_debug_mode)
printf("Kerberos V5: error getting forwarded creds - %s\r\n",
error_message(r));
krb5_free_creds(local_creds);
return;
}
/* Send forwarded credentials */
if (!Data(ap, KRB_FORWARD, forw_creds.data, forw_creds.length)) {
if (auth_debug_mode)
printf("Not enough room for authentication data\r\n");
}
else {
if (auth_debug_mode)
printf("Forwarded local Kerberos V5 credentials to server\r\n");
}
krb5_free_creds(local_creds);
}
#endif /* FORWARD */
#endif /* KRB5 */
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