path: root/src/lib/krb425/sendauth.c

/*
 * lib/krb425/sendauth.c
 *
 * Copyright 1987,1988,1990 by the Massachusetts Institute of Technology.
 * All Rights Reserved.
 *
 * 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.
 * 
 *
 */


#include "krb425.h"

#include <sys/types.h>
#include <syslog.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>

#define	KRB_SENDAUTH_VERS "AUTHV0.1" /* MUST be KRB_SENDAUTH_VLEN chars */
/*
 * If the protocol changes, you will need to change the version string
 * and make appropriate changes in krb_recvauth.c
 */

extern int errno;

extern char *krb_get_phost();

/*
 * This file contains two routines: krb_sendauth() and krb_sendsrv().
 *
 * krb_sendauth() transmits a ticket over a file descriptor for a
 * desired service, instance, and realm, doing mutual authentication
 * with the server if desired.
 *
 * krb_sendsvc() sends a service name to a remote knetd server.
 */

/*
 * The first argument to krb_sendauth() contains a bitfield of
 * options (the options are defined in "krb.h"):
 *
 * KOPT_DONT_CANON	Don't canonicalize instance as a hostname.
 *			(If this option is not chosen, krb_get_phost()
 *			is called to canonicalize it.)
 *
 * KOPT_DONT_MK_REQ 	Don't request server ticket from Kerberos.
 *			A ticket must be supplied in the "ticket"
 *			argument.
 *			(If this option is not chosen, and there
 *			is no ticket for the given server in the
 *			ticket cache, one will be fetched using
 *			krb_mk_req() and returned in "ticket".)
 *
 * KOPT_DO_MUTUAL	Do mutual authentication, requiring that the
 * 			receiving server return the checksum+1 encrypted
 *			in the session key.  The mutual authentication
 *			is done using krb_mk_priv() on the other side
 *			(see "recvauth.c") and krb_rd_priv() on this
 *			side.
 *
 * The "fd" argument is a file descriptor to write to the remote
 * server on.  The "ticket" argument is used to store the new ticket
 * from the krb_mk_req() call. If the KOPT_DONT_MK_REQ options is
 * chosen, the ticket must be supplied in the "ticket" argument.
 * The "service", "inst", and "realm" arguments identify the ticket.
 * If "realm" is null, the local realm is used.
 *
 * The following arguments are only needed if the KOPT_DO_MUTUAL option
 * is chosen:
 *
 *   The "checksum" argument is a number that the server will add 1 to
 *   to authenticate itself back to the client; the "msg_data" argument
 *   holds the returned mutual-authentication message from the server
 *   (i.e., the checksum+1); the "cred" structure is used to hold the
 *   session key of the server, extracted from the ticket file, for use
 *   in decrypting the mutual authentication message from the server;
 *   and "schedule" holds the key schedule for that decryption.  The
 *   the local and server addresses are given in "laddr" and "faddr".
 *
 * The application protocol version number (of up to KRB_SENDAUTH_VLEN
 * characters) is passed in "version".
 *
 * If all goes well, KSUCCESS is returned, otherwise some error code.
 *
 * The format of the message sent to the server is:
 *
 * Size			Variable		Field
 * ----			--------		-----
 *
 * KRB_SENDAUTH_VLEN	KRB_SENDAUTH_VER	sendauth protocol
 * bytes					version number
 *
 * KRB_SENDAUTH_VLEN	version			application protocol
 * bytes					version number
 *
 * 4 bytes		ticket->length		length of ticket
 *
 * ticket->length	ticket->dat		ticket itself
 */

/*
 * XXX: Note that krb_rd_priv() is coded in such a way that
 * "msg_data->app_data" will be pointing into "priv_buf", which
 * will disappear when krb_sendauth() returns.
 */

int
krb_sendauth(options, fd, ticket, service, inst, realm, checksum,
	msg_data, cred, schedule, laddr, faddr, version)
long options;			 /* bit-pattern of options */
int fd;				 /* file descriptor to write onto */
KTEXT ticket;			 /* where to put ticket (return); or
				  * supplied in case of KOPT_DONT_MK_REQ */
char *service, *inst, *realm;	 /* service name, instance, realm */
u_long checksum;		 /* checksum to include in request */
MSG_DAT *msg_data;		 /* mutual auth MSG_DAT (return) */
CREDENTIALS *cred;		 /* credentials (return) */
Key_schedule schedule;		 /* key schedule (return) */
struct sockaddr_in *laddr;	 /* local address */
struct sockaddr_in *faddr;	 /* address of foreign host on fd */
char *version;			 /* version string */
{
    int rem, i, cc;
    char srv_inst[INST_SZ];
    char krb_realm[REALM_SZ];
    char buf[BUFSIZ];
    long tkt_len;
    u_char priv_buf[1024];
    u_long cksum;

    rem=KSUCCESS;

    /* get current realm if not passed in */
    if (!realm) {
	rem = krb_get_lrealm(krb_realm,1);
	if (rem != KSUCCESS)
	    return(rem);
	realm = krb_realm;
    }

    /* copy instance into local storage, canonicalizing if desired */
    if (options & KOPT_DONT_CANON)
	(void) strncpy(srv_inst, inst, INST_SZ);
    else
	(void) strncpy(srv_inst, krb_get_phost(inst), INST_SZ);

    /* get the ticket if desired */
    if (!(options & KOPT_DONT_MK_REQ)) {
	rem = krb_mk_req(ticket, service, srv_inst, realm, checksum);
	if (rem != KSUCCESS)
	    return(rem);
    }

    /* if mutual auth, get credentials so we have service session
       keys for decryption below */
    if (options & KOPT_DO_MUTUAL)
	if (cc = krb_get_cred(service, srv_inst, realm, cred))
	    return(cc);

    /* zero the buffer */
    (void) memset(buf, 0, BUFSIZ);

    /* insert version strings */
    (void) strncpy(buf, KRB_SENDAUTH_VERS, KRB_SENDAUTH_VLEN);
    (void) strncpy(buf+KRB_SENDAUTH_VLEN, version, KRB_SENDAUTH_VLEN);

    /* increment past vers strings */
    i = 2*KRB_SENDAUTH_VLEN;

    /* put ticket length into buffer */
    tkt_len = htonl((unsigned long) ticket->length);
    (void) memcpy(buf+i, (char *) &tkt_len, sizeof(tkt_len));
    i += sizeof(tkt_len);

    /* put ticket into buffer */
    (void) memcpy(buf+i, (char *) ticket->dat, ticket->length);
    i += ticket->length;

    /* write the request to the server */
    if ((cc = krb_net_write(fd, buf, i)) != i)
	return(cc);

    /* mutual authentication, if desired */
    if (options & KOPT_DO_MUTUAL) {
	int r;
	/* get the length of the reply */
	if ((r = krb_net_read(fd, (char *) &tkt_len, sizeof(tkt_len))) !=
	    sizeof(tkt_len)) {
#ifdef	EBUG
	    EPRINT "krb_net_read(%d, tkt_len, %d) returns %d\n",
			fd, sizeof(tkt_len), r);
	    ERROR(errno);
#endif
	    return(errno);
	}
	tkt_len = ntohl((unsigned long)tkt_len);

	/* if the length is negative, the server failed to recognize us. */
	if ((tkt_len < 0) || (tkt_len > sizeof(priv_buf)))
	    return(KFAILURE);	 /* XXX */
	/* read the reply... */
	if (krb_net_read(fd, (char *)priv_buf, (int) tkt_len) != (int) tkt_len)
	    return(errno);

	/* ...and decrypt it */
#ifndef NOENCRYPTION
  	key_sched(cred->session, schedule);
#endif /* !NOENCRYPTION */
	if (cc = krb_rd_priv(priv_buf,(unsigned long) tkt_len, schedule,
			     cred->session, faddr, laddr, msg_data))
	    return(cc);

	/* fetch the (modified) checksum */
	(void) memcpy((char *)&cksum, (char *)msg_data->app_data,
		      sizeof(cksum));
	cksum = ntohl(cksum);

	/* if it doesn't match, fail */
	if (cksum != checksum + 1)
	    return(KFAILURE);	 /* XXX */
    }
    return(KSUCCESS);
}

#ifdef ATHENA_COMPAT
/*
 * krb_sendsvc
 */

int
krb_sendsvc(fd, service)
int fd;
char *service;
{
    /* write the service name length and then the service name to
       the fd */
    long serv_length;
    int cc;

    serv_length = htonl((unsigned long)strlen(service));
    if ((cc = krb_net_write(fd, (char *) &serv_length,
	sizeof(serv_length)))
	!= sizeof(serv_length))
	return(cc);
    if ((cc = krb_net_write(fd, service, strlen(service)))
	!= strlen(service))
	return(cc);
    return(KSUCCESS);
}
#endif /* ATHENA_COMPAT */