/* 
 * $Header: /afs/dev.mit.edu/source/repository/athena/bin/rkinit/rkinitd/krb.c,v 1.1 1989-11-12 19:35:48 qjb Exp $
 * $Source: /afs/dev.mit.edu/source/repository/athena/bin/rkinit/rkinitd/krb.c,v $
 * $Author: qjb $
 *
 * This file contains all of the kerberos part of rkinitd.
 */

#if !defined(lint) && !defined(SABER)
static char *rcsid = "$Header: /afs/dev.mit.edu/source/repository/athena/bin/rkinit/rkinitd/krb.c,v 1.1 1989-11-12 19:35:48 qjb Exp $";
#endif lint || SABER

#include <stdio.h>
#include <sys/types.h>
#include <errno.h>
#include <syslog.h>
#include <netinet/in.h>
#include <setjmp.h>
#include <pwd.h>
#include <krb.h>
#include <des.h>

#include <rkinit.h>
#include <rkinit_private.h>
#include <rkinit_err.h>

#define FAILURE (!RKINIT_SUCCESS)

extern int errno;
extern char *sys_errlist[];

static char errbuf[BUFSIZ];

typedef struct {
    jmp_buf env;
} rkinitd_intkt_info;

static void this_phost(host, hostlen)
  char *host;
  int hostlen;
{
    char this_host[MAXHOSTNAMELEN + 1];

    BCLEAR(this_host);
    
    if (gethostname(this_host, sizeof(this_host)) < 0) {
	sprintf(errbuf, "gethostname: %s", sys_errlist[errno]);
	rkinit_errmsg(errbuf);
	error();
	exit(1);
    }

    strncpy(host, krb_get_phost(this_host), hostlen - 1);
}

static int decrypt_tkt(user, instance, realm, arg, key_proc, cipp)
  char *user;
  char *instance;
  char *realm;
  char *arg;
  int (*key_proc)();
  KTEXT *cipp;
{
    MSG_DAT msg_data;		/* Message data containing decrypted data */
    KTEXT_ST auth;		/* Authenticator */
    AUTH_DAT auth_dat;		/* Authentication data */
    KTEXT cip = *cipp;
    MSG_DAT scip;
    int status = 0;
    des_cblock key;
    des_key_schedule sched;
    char phost[MAXHOSTNAMELEN + 1];
    struct sockaddr_in caddr;	/* client internet address */
    struct sockaddr_in saddr;	/* server internet address */

    rkinitd_intkt_info *rii = (rkinitd_intkt_info *)arg;

    u_char enc_data[MAX_KTXT_LEN];

    SBCLEAR(auth);
    SBCLEAR(auth_dat);
    SBCLEAR(scip);
    BCLEAR(enc_data);

    scip.app_data = enc_data;

    /* 
     * Exchange with the client our response from the KDC (ticket encrypted
     * in user's private key) for the same ticket encrypted in our
     * (not yet known) session key.
     */

    rpc_exchange_tkt(cip, &scip);

    /* 
     * Get the authenticator 
     */

    SBCLEAR(auth);

    rpc_getauth(&auth, &caddr, &saddr);

    /* 
     * Decode authenticator and extract session key.  The first zero
     * means we don't care what host this comes from.  This needs to
     * be done with euid of root so that /etc/srvtab can be read.
     */

    BCLEAR(phost);
    this_phost(phost, sizeof(phost));

    /* 
     * This function has to use longjmp to return to the caller
     * because the kerberos library routine that calls it doesn't
     * pay attention to the return value it gives.  That means that
     * if any of these routines failed, the error returned to the client
     * would be "password incorrect".
     */

    if (status = krb_rd_req(&auth, KEY, phost, caddr.sin_addr.s_addr, 
			    &auth_dat, KEYFILE)) {
	sprintf(errbuf, "krb_rd_req: %s", krb_err_txt[status]);
	rkinit_errmsg(errbuf);
	longjmp(rii->env, status);
    }

    bcopy(auth_dat.session, key, sizeof(key));
    if (des_key_sched(key, sched)) {
	sprintf(errbuf, "Error in des_key_sched");
	rkinit_errmsg(errbuf);
	longjmp(rii->env, RKINIT_DES);
    }

    /* Decrypt the data. */
    if ((status = 
	 krb_rd_priv((u_char *)scip.app_data, scip.app_length, 
		     sched, key, &caddr, &saddr, &msg_data)) == KSUCCESS) {
	cip->length = msg_data.app_length;
	bcopy(msg_data.app_data, cip->dat, msg_data.app_length);
	cip->dat[cip->length] = 0;
    } 
    else {
	sprintf(errbuf, "krb_rd_priv: %s", krb_err_txt[status]);
	rkinit_errmsg(errbuf);
	longjmp(rii->env, status);
    }
    
    return(status);
}

static int validate_user(aname, inst, realm, username, errmsg)
  char *aname;
  char *inst;
  char *realm;
  char *username;
  char *errmsg;
{
    struct passwd *pwnam;	/* For access_check and uid */
    AUTH_DAT auth_dat;

    SBCLEAR(auth_dat);

    if ((pwnam = getpwnam(username)) == NULL) {
	sprintf(errmsg, "%s does not exist on the remote host.", username);
	return(FAILURE);
    }

    strcpy(auth_dat.pname, aname);
    strcpy(auth_dat.pinst, inst);
    strcpy(auth_dat.prealm, realm);

    if (kuserok(&auth_dat, username) != KSUCCESS) {
	sprintf(errmsg, "%s has not allowed you to log in with", username);
	if (strlen(auth_dat.pinst))
	    sprintf(errmsg, "%s %s.%s", errmsg, auth_dat.pname, 
		    auth_dat.pinst);
	else
	    sprintf(errmsg, "%s %s", errmsg, auth_dat.pname);
	sprintf(errmsg, "%s@%s tickets.", errmsg, auth_dat.prealm);
	return(FAILURE);
    }
    
    /* 
     * Set real uid to owner of ticket file.  The library takes care
     * of making the appropriate change. 
     */
    if (setruid(pwnam->pw_uid) < 0) {
	sprintf(errmsg,
		"Failure setting ruid to %d: %s\n", sys_errlist[errno]);
	strcpy(errbuf, errmsg);
	error();
	return(FAILURE);
    }
	
    return(RKINIT_SUCCESS);
}

int get_tickets(version)
  int version;
{
    rkinit_info info;
    AUTH_DAT auth_dat;

    int status;
    char errmsg[BUFSIZ];	/* error message for client */

    rkinitd_intkt_info rii;

    SBCLEAR(info);
    SBCLEAR(auth_dat);
    BCLEAR(errmsg);
    SBCLEAR(rii);

    rpc_get_rkinit_info(&info);

    /* 
     * The validate_user routine makes sure that the principal in question
     * is allowed to log in as username, and if so, does a setuid(localuid).
     * If there is an access violation or an error in setting the uid,
     * an error is returned and the string errmsg is initialized with 
     * an error message that will be sent back to the client.
     */
    if ((status = validate_user(info.aname, info.inst, info.realm, 
				info.username, errmsg)) != RKINIT_SUCCESS) {
	rpc_send_error(errmsg);
	exit(0);
    }
    else
	rpc_send_success();

    /* 
     * If the name of a ticket file was specified, set it; otherwise, 
     * just use the default. 
     */
    if (strlen(info.tktfilename))
	krb_set_tkt_string(info.tktfilename);
    
    /* 
     * Call internal kerberos library routine so that we can supply
     * our own ticket decryption routine.
     */

    /* 
     * We need a setjmp here because krb_get_in_tkt ignores the
     * return value of decrypt_tkt.  Thus if we want any of its
     * return values to reach the client, we have to jump out of 
     * the routine.
     */

    if (setjmp(rii.env) == 0) {
	if (status = krb_get_in_tkt(info.aname, info.inst, info.realm, 
				    info.sname, info.sinst, info.lifetime,
				    NULL, decrypt_tkt, (char *)&rii)) {
	    strcpy(errmsg, krb_err_txt[status]);
	    rpc_send_error(errmsg);
	}
	else
	    rpc_send_success();
    }
    else
	rpc_send_error(errbuf);
    
    return(RKINIT_SUCCESS);
}