path: root/usr.bin/telnet/auth.c

/*     $OpenBSD: auth.c,v 1.2 2009/10/27 23:59:44 deraadt Exp $    */

/*-
 * 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. 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.
 */

/*
 * This source code is no longer held under any constraint of USA
 * `cryptographic laws' since it was exported legally.  The cryptographic
 * functions were removed from the code and a "Bones" distribution was
 * made.  A Commodity Jurisdiction Request #012-94 was filed with the
 * USA State Department, who handed it to the Commerce department.  The
 * code was determined to fall under General License GTDA under ECCN 5D96G,
 * and hence exportable.  The cryptographic interfaces were re-added by Eric
 * Young, and then KTH proceeded to maintain the code in the free world.
 *
 */

/*
 * 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.
 */

/* "$KTH: auth.c,v 1.23 2000/01/18 03:09:34 assar Exp $" */

#if	defined(AUTHENTICATION)
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <signal.h>
#define	AUTH_NAMES
#include <arpa/telnet.h>
#include <stdlib.h>
#include <string.h>

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

#define	typemask(x)		(1<<((x)-1))

#ifdef	KRB4_ENCPWD
extern krb4encpwd_init();
extern krb4encpwd_send();
extern krb4encpwd_is();
extern krb4encpwd_reply();
extern krb4encpwd_status();
extern krb4encpwd_printsub();
#endif

#ifdef	RSA_ENCPWD
extern rsaencpwd_init();
extern rsaencpwd_send();
extern rsaencpwd_is();
extern rsaencpwd_reply();
extern rsaencpwd_status();
extern rsaencpwd_printsub();
#endif

int auth_debug_mode = 0;
int auth_has_failed  = 0;
int auth_enable_encrypt = 0;
static 	const	char	*Name = "Noname";
static	int	Server = 0;
static	Authenticator	*authenticated = 0;
static	int	authenticating = 0;
static	int	validuser = 0;
static	unsigned char	_auth_send_data[256];
static	unsigned char	*auth_send_data;
static	int	auth_send_cnt = 0;

/*
 * Authentication types supported.  Plese note that these are stored
 * in priority order, i.e. try the first one first.
 */
Authenticator authenticators[] = {
#ifdef UNSAFE
    { AUTHTYPE_UNSAFE, AUTH_WHO_CLIENT|AUTH_HOW_ONE_WAY,
      unsafe_init,
      unsafe_send,
      unsafe_is,
      unsafe_reply,
      unsafe_status,
      unsafe_printsub },
#endif
#ifdef SRA
    { AUTHTYPE_SRA, AUTH_WHO_CLIENT|AUTH_HOW_ONE_WAY,
      sra_init,
      sra_send,
      sra_is,
      sra_reply,
      sra_status,
      sra_printsub },
#endif
#ifdef	SPX
    { AUTHTYPE_SPX, AUTH_WHO_CLIENT|AUTH_HOW_MUTUAL,
      spx_init,
      spx_send,
      spx_is,
      spx_reply,
      spx_status,
      spx_printsub },
    { AUTHTYPE_SPX, AUTH_WHO_CLIENT|AUTH_HOW_ONE_WAY,
      spx_init,
      spx_send,
      spx_is,
      spx_reply,
      spx_status,
      spx_printsub },
#endif
#ifdef	KRB5
    { AUTHTYPE_KERBEROS_V5, AUTH_WHO_CLIENT|AUTH_HOW_MUTUAL,
      kerberos5_init,
      kerberos5_send_mutual,
      kerberos5_is,
      kerberos5_reply,
      kerberos5_status,
      kerberos5_printsub },
    { AUTHTYPE_KERBEROS_V5, AUTH_WHO_CLIENT|AUTH_HOW_ONE_WAY,
      kerberos5_init,
      kerberos5_send_oneway,
      kerberos5_is,
      kerberos5_reply,
      kerberos5_status,
      kerberos5_printsub },
#endif
#ifdef	KRB4
    { AUTHTYPE_KERBEROS_V4, AUTH_WHO_CLIENT|AUTH_HOW_MUTUAL,
      kerberos4_init,
      kerberos4_send_mutual,
      kerberos4_is,
      kerberos4_reply,
      kerberos4_status,
      kerberos4_printsub },
    { AUTHTYPE_KERBEROS_V4, AUTH_WHO_CLIENT|AUTH_HOW_ONE_WAY,
      kerberos4_init,
      kerberos4_send_oneway,
      kerberos4_is,
      kerberos4_reply,
      kerberos4_status,
      kerberos4_printsub },
#endif
#ifdef	KRB4_ENCPWD
    { AUTHTYPE_KRB4_ENCPWD, AUTH_WHO_CLIENT|AUTH_HOW_MUTUAL,
      krb4encpwd_init,
      krb4encpwd_send,
      krb4encpwd_is,
      krb4encpwd_reply,
      krb4encpwd_status,
      krb4encpwd_printsub },
#endif
#ifdef	RSA_ENCPWD
    { AUTHTYPE_RSA_ENCPWD, AUTH_WHO_CLIENT|AUTH_HOW_ONE_WAY,
      rsaencpwd_init,
      rsaencpwd_send,
      rsaencpwd_is,
      rsaencpwd_reply,
      rsaencpwd_status,
      rsaencpwd_printsub },
#endif
    { 0, },
};

static Authenticator NoAuth = { 0 };

static int	i_support = 0;
static int	i_wont_support = 0;

Authenticator *
findauthenticator(int type, int way)
{
    Authenticator *ap = authenticators;

    while (ap->type && (ap->type != type || ap->way != way))
	++ap;
    return(ap->type ? ap : 0);
}

void
auth_init(const char *name, int server)
{
    Authenticator *ap = authenticators;

    Server = server;
    Name = name;

    i_support = 0;
    authenticated = 0;
    authenticating = 0;
    while (ap->type) {
	if (!ap->init || (*ap->init)(ap, server)) {
	    i_support |= typemask(ap->type);
	    if (auth_debug_mode)
		printf(">>>%s: I support auth type %d %d\r\n",
		       Name,
		       ap->type, ap->way);
	}
	else if (auth_debug_mode)
	    printf(">>>%s: Init failed: auth type %d %d\r\n",
		   Name, ap->type, ap->way);
	++ap;
    }
}

void
auth_disable_name(char *name)
{
    int x;
    for (x = 0; x < AUTHTYPE_CNT; ++x) {
	if (!strcasecmp(name, AUTHTYPE_NAME(x))) {
	    i_wont_support |= typemask(x);
	    break;
	}
    }
}

int
getauthmask(char *type, int *maskp)
{
    int x;

    if (!strcasecmp(type, AUTHTYPE_NAME(0))) {
	*maskp = -1;
	return(1);
    }

    for (x = 1; x < AUTHTYPE_CNT; ++x) {
	if (!strcasecmp(type, AUTHTYPE_NAME(x))) {
	    *maskp = typemask(x);
	    return(1);
	}
    }
    return(0);
}

int
auth_enable(char *type)
{
    return(auth_onoff(type, 1));
}

int
auth_disable(char *type)
{
    return(auth_onoff(type, 0));
}

int
auth_onoff(char *type, int on)
{
    int i, mask = -1;
    Authenticator *ap;

    if (!strcasecmp(type, "?") || !strcasecmp(type, "help")) {
	printf("auth %s 'type'\n", on ? "enable" : "disable");
	printf("Where 'type' is one of:\n");
	printf("\t%s\n", AUTHTYPE_NAME(0));
	mask = 0;
	for (ap = authenticators; ap->type; ap++) {
	    if ((mask & (i = typemask(ap->type))) != 0)
		continue;
	    mask |= i;
	    printf("\t%s\n", AUTHTYPE_NAME(ap->type));
	}
	return(0);
    }

    if (!getauthmask(type, &mask)) {
	printf("%s: invalid authentication type\n", type);
	return(0);
    }
    if (on)
	i_wont_support &= ~mask;
    else
	i_wont_support |= mask;
    return(1);
}

int
auth_togdebug(int on)
{
    if (on < 0)
	auth_debug_mode ^= 1;
    else
	auth_debug_mode = on;
    printf("auth debugging %s\n", auth_debug_mode ? "enabled" : "disabled");
    return(1);
}

int
auth_status(void)
{
    Authenticator *ap;
    int i, mask;

    if (i_wont_support == -1)
	printf("Authentication disabled\n");
    else
	printf("Authentication enabled\n");

    mask = 0;
    for (ap = authenticators; ap->type; ap++) {
	if ((mask & (i = typemask(ap->type))) != 0)
	    continue;
	mask |= i;
	printf("%s: %s\n", AUTHTYPE_NAME(ap->type),
	       (i_wont_support & typemask(ap->type)) ?
	       "disabled" : "enabled");
    }
    return(1);
}

/*
 * This routine is called by the server to start authentication
 * negotiation.
 */
void
auth_request(void)
{
    static unsigned char str_request[64] = { IAC, SB,
					     TELOPT_AUTHENTICATION,
					     TELQUAL_SEND, };
    Authenticator *ap = authenticators;
    unsigned char *e = str_request + 4;

    if (!authenticating) {
	authenticating = 1;
	while (ap->type) {
	    if (i_support & ~i_wont_support & typemask(ap->type)) {
		if (auth_debug_mode) {
		    printf(">>>%s: Sending type %d %d\r\n",
			   Name, ap->type, ap->way);
		}
		*e++ = ap->type;
		*e++ = ap->way;
	    }
	    ++ap;
	}
	*e++ = IAC;
	*e++ = SE;
	telnet_net_write(str_request, e - str_request);
	printsub('>', &str_request[2], e - str_request - 2);
    }
}

/*
 * This is called when an AUTH SEND is received.
 * It should never arrive on the server side (as only the server can
 * send an AUTH SEND).
 * You should probably respond to it if you can...
 *
 * If you want to respond to the types out of order (i.e. even
 * if he sends  LOGIN KERBEROS and you support both, you respond
 * with KERBEROS instead of LOGIN (which is against what the
 * protocol says)) you will have to hack this code...
 */
void
auth_send(unsigned char *data, int cnt)
{
    Authenticator *ap;
    static unsigned char str_none[] = { IAC, SB, TELOPT_AUTHENTICATION,
					TELQUAL_IS, AUTHTYPE_NULL, 0,
					IAC, SE };
    if (Server) {
	if (auth_debug_mode) {
	    printf(">>>%s: auth_send called!\r\n", Name);
	}
	return;
    }

    if (auth_debug_mode) {
	printf(">>>%s: auth_send got:", Name);
	printd(data, cnt); printf("\r\n");
    }

    /*
     * Save the data, if it is new, so that we can continue looking
     * at it if the authorization we try doesn't work
     */
    if (data < _auth_send_data ||
	data > _auth_send_data + sizeof(_auth_send_data)) {
	auth_send_cnt = cnt > sizeof(_auth_send_data)
	    ? sizeof(_auth_send_data)
	    : cnt;
	memmove(_auth_send_data, data, auth_send_cnt);
	auth_send_data = _auth_send_data;
    } else {
	/*
	 * This is probably a no-op, but we just make sure
	 */
	auth_send_data = data;
	auth_send_cnt = cnt;
    }
    while ((auth_send_cnt -= 2) >= 0) {
	if (auth_debug_mode)
	    printf(">>>%s: He supports %d\r\n",
		   Name, *auth_send_data);
	if ((i_support & ~i_wont_support) & typemask(*auth_send_data)) {
	    ap = findauthenticator(auth_send_data[0],
				   auth_send_data[1]);
	    if (ap && ap->send) {
		if (auth_debug_mode)
		    printf(">>>%s: Trying %d %d\r\n",
			   Name, auth_send_data[0],
			   auth_send_data[1]);
		if ((*ap->send)(ap)) {
		    /*
		     * Okay, we found one we like
		     * and did it.
		     * we can go home now.
		     */
		    if (auth_debug_mode)
			printf(">>>%s: Using type %d\r\n",
			       Name, *auth_send_data);
		    auth_send_data += 2;
		    return;
		}
	    }
	    /* else
	     *	just continue on and look for the
	     *	next one if we didn't do anything.
	     */
	}
	auth_send_data += 2;
    }
    telnet_net_write(str_none, sizeof(str_none));
    printsub('>', &str_none[2], sizeof(str_none) - 2);
    if (auth_debug_mode)
	printf(">>>%s: Sent failure message\r\n", Name);
    auth_finished(0, AUTH_REJECT);
    auth_has_failed = 1;
#ifdef KANNAN
    /*
     *  We requested strong authentication, however no mechanisms worked.
     *  Therefore, exit on client end.
     */
    printf("Unable to securely authenticate user ... exit\n");
    exit(0);
#endif /* KANNAN */
}

void
auth_send_retry(void)
{
    /*
     * if auth_send_cnt <= 0 then auth_send will end up rejecting
     * the authentication and informing the other side of this.
	 */
    auth_send(auth_send_data, auth_send_cnt);
}

void
auth_is(unsigned char *data, int cnt)
{
    Authenticator *ap;

    if (cnt < 2)
	return;

    if (data[0] == AUTHTYPE_NULL) {
	auth_finished(0, AUTH_REJECT);
	return;
    }

    if ((ap = findauthenticator(data[0], data[1]))) {
	if (ap->is)
	    (*ap->is)(ap, data+2, cnt-2);
    } else if (auth_debug_mode)
	printf(">>>%s: Invalid authentication in IS: %d\r\n",
	       Name, *data);
}

void
auth_reply(unsigned char *data, int cnt)
{
    Authenticator *ap;

    if (cnt < 2)
	return;

    if ((ap = findauthenticator(data[0], data[1]))) {
	if (ap->reply)
	    (*ap->reply)(ap, data+2, cnt-2);
    } else if (auth_debug_mode)
	printf(">>>%s: Invalid authentication in SEND: %d\r\n",
	       Name, *data);
}

void
auth_name(unsigned char *data, int cnt)
{
    char savename[256];

    if (cnt < 1) {
	if (auth_debug_mode)
	    printf(">>>%s: Empty name in NAME\r\n", Name);
	return;
    }
    if (cnt > sizeof(savename) - 1) {
	if (auth_debug_mode)
	    printf(">>>%s: Name in NAME (%d) exceeds %lu length\r\n",
		   Name, cnt, (unsigned long)(sizeof(savename)-1));
	return;
    }
    memmove(savename, data, cnt);
    savename[cnt] = '\0';	/* Null terminate */
    if (auth_debug_mode)
	printf(">>>%s: Got NAME [%s]\r\n", Name, savename);
    auth_encrypt_user(savename);
}

int
auth_sendname(unsigned char *cp, int len)
{
    static unsigned char str_request[256+6]
	= { IAC, SB, TELOPT_AUTHENTICATION, TELQUAL_NAME, };
    unsigned char *e = str_request + 4;
    unsigned char *ee = &str_request[sizeof(str_request)-2];

    while (--len >= 0) {
	if ((*e++ = *cp++) == IAC)
	    *e++ = IAC;
	if (e >= ee)
	    return(0);
    }
    *e++ = IAC;
    *e++ = SE;
    telnet_net_write(str_request, e - str_request);
    printsub('>', &str_request[2], e - &str_request[2]);
    return(1);
}

void
auth_finished(Authenticator *ap, int result)
{
    if (!(authenticated = ap))
	authenticated = &NoAuth;
    validuser = result;
}

/* ARGSUSED */
static void
auth_intr(int sig)
{
    auth_finished(0, AUTH_REJECT);
}

int
auth_wait(char *name, size_t name_sz)
{
    if (auth_debug_mode)
	printf(">>>%s: in auth_wait.\r\n", Name);

    if (Server && !authenticating)
	return(0);

    signal(SIGALRM, auth_intr);
    alarm(30);
    while (!authenticated)
	if (telnet_spin())
	    break;
    alarm(0);
    signal(SIGALRM, SIG_DFL);

    /*
     * Now check to see if the user is valid or not
     */
    if (!authenticated || authenticated == &NoAuth)
	return(AUTH_REJECT);

    if (validuser == AUTH_VALID)
	validuser = AUTH_USER;

    if (authenticated->status)
	validuser = (*authenticated->status)(authenticated,
					     name, name_sz,
					     validuser);
    return(validuser);
}

void
auth_debug(int mode)
{
    auth_debug_mode = mode;
}

void
auth_printsub(unsigned char *data, int cnt, unsigned char *buf, int buflen)
{
    Authenticator *ap;

    if ((ap = findauthenticator(data[1], data[2])) && ap->printsub)
	(*ap->printsub)(data, cnt, buf, buflen);
    else
	auth_gen_printsub(data, cnt, buf, buflen);
}

void
auth_gen_printsub(unsigned char *data, int cnt, unsigned char *buf, int buflen)
{
    unsigned char *cp;
    unsigned char tbuf[16];

    cnt -= 3;
    data += 3;
    buf[buflen-1] = '\0';
    buf[buflen-2] = '*';
    buflen -= 2;
    for (; cnt > 0; cnt--, data++) {
	snprintf(tbuf, sizeof(tbuf), " %d", *data);
	for (cp = tbuf; *cp && buflen > 0; --buflen)
	    *buf++ = *cp++;
	if (buflen <= 0)
	    return;
    }
    *buf = '\0';
}
#endif