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auth.c

/*-
 * 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.
 */

/*
 * 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.
 */

#include <config.h>

RCSID("$Id: auth.c,v 1.25 2002/01/18 12:58:48 joda Exp $");

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

#include <roken.h>

#ifdef SOCKS
#include <socks.h>
#endif

#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((char*)tbuf, sizeof(tbuf), " %d", *data);
      for (cp = tbuf; *cp && buflen > 0; --buflen)
          *buf++ = *cp++;
      if (buflen <= 0)
          return;
    }
    *buf = '\0';
}
#endif

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