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/*
* g_ad_tkt.c
*
* Copyright 1986, 1987, 1988 by the Massachusetts Institute
* of Technology.
*
* For copying and distribution information, please see the file
* <mit-copyright.h>.
*/
#include "mit-copyright.h"
#include "krb.h"
#include "des.h"
#include "prot.h"
#include <string.h>
#include <stdio.h>
extern int krb_debug;
extern int swap_bytes;
/*
* get_ad_tkt obtains a new service ticket from Kerberos, using
* the ticket-granting ticket which must be in the ticket file.
* It is typically called by krb_mk_req() when the client side
* of an application is creating authentication information to be
* sent to the server side.
*
* get_ad_tkt takes four arguments: three pointers to strings which
* contain the name, instance, and realm of the service for which the
* ticket is to be obtained; and an integer indicating the desired
* lifetime of the ticket.
*
* It returns an error status if the ticket couldn't be obtained,
* or AD_OK if all went well. The ticket is stored in the ticket
* cache.
*
* The request sent to the Kerberos ticket-granting service looks
* like this:
*
* pkt->dat
*
* TEXT original contents of authenticator+ticket
* pkt->dat built in krb_mk_req call
*
* 4 bytes time_ws always 0 (?) FIXME!
* char lifetime lifetime argument passed
* string service service name argument
* string sinstance service instance arg.
*
* See "prot.h" for the reply packet layout and definitions of the
* extraction macros like pkt_version(), pkt_msg_type(), etc.
*/
get_ad_tkt(service,sinstance,realm,lifetime)
char *service;
char *sinstance;
char *realm;
int lifetime;
{
unsigned long rep_err_code;
KTEXT_ST pkt_st;
KTEXT pkt = & pkt_st; /* Packet to KDC */
KTEXT_ST rpkt_st;
KTEXT rpkt = &rpkt_st; /* Returned packet */
KTEXT_ST cip_st;
KTEXT cip = &cip_st; /* Returned Ciphertext */
KTEXT_ST tkt_st;
KTEXT tkt = &tkt_st; /* Current ticket */
C_Block ses; /* Session key for tkt */
CREDENTIALS cr;
int kvno; /* Kvno for session key */
char lrealm[REALM_SZ];
Key_schedule key_s;
KRB4_32 time_ws = 0;
char s_name[SNAME_SZ];
char s_instance[INST_SZ];
int msg_byte_order;
int kerror;
char rlm[REALM_SZ];
char *ptr;
unsigned KRB4_32 t_local; /* Must be 4 bytes long for memcpy below! */
KRB4_32 t_diff; /* Difference between timestamps */
unsigned KRB4_32 kdc_time; /* KDC time */
unsigned int t_switch;
if ((kerror = krb_get_tf_realm(TKT_FILE, lrealm)) != KSUCCESS)
return(kerror);
/* Create skeleton of packet to be sent */
pkt->length = 0;
/*
* Look for the session key (and other stuff we don't need)
* in the ticket file for krbtgt.realm@lrealm where "realm"
* is the service's realm (passed in "realm" argument) and
* "lrealm" is the realm of our initial ticket (the local realm).
* If that fails, and the server's realm and the local realm are
* the same thing, give up - no TGT available for local realm.
*
* If the server realm and local realm are different, though,
* try getting a ticket-granting ticket for the server's realm,
* i.e. a ticket for "krbtgt.alienrealm@lrealm", by calling get_ad_tkt().
* If that succeeds, the ticket will be in ticket cache, get it
* into the "cr" structure by calling krb_get_cred().
*/
if ((kerror = krb_get_cred("krbtgt",realm,lrealm,&cr)) != KSUCCESS) {
/*
* If realm == lrealm, we have no hope, so let's not even try.
*/
if ((strncmp(realm, lrealm, REALM_SZ)) == 0)
return(AD_NOTGT);
else{
if ((kerror =
get_ad_tkt("krbtgt",realm,lrealm,lifetime)) != KSUCCESS) {
if (kerror == KDC_PR_UNKNOWN) /* no cross-realm ticket */
return AD_NOTGT; /* So call it no ticket */
return(kerror);
}
if ((kerror = krb_get_cred("krbtgt",realm,lrealm,&cr)) != KSUCCESS)
return(kerror);
}
}
/*
* Make up a request packet to the "krbtgt.realm@lrealm".
* Start by calling krb_mk_req() which puts ticket+authenticator
* into "pkt". Then tack other stuff on the end.
*/
kerror = krb_mk_req(pkt,"krbtgt",realm,lrealm,0L);
if (kerror)
return(AD_NOTGT);
/* timestamp */ /* FIXME -- always 0 now, should we fill it in??? */
memcpy((char *) (pkt->dat+pkt->length), (char *) &time_ws, 4);
pkt->length += 4;
*(pkt->dat+(pkt->length)++) = (char) lifetime;
(void) strcpy((char *) (pkt->dat+pkt->length),service);
pkt->length += 1 + strlen(service);
(void) strcpy((char *)(pkt->dat+pkt->length),sinstance);
pkt->length += 1 + strlen(sinstance);
rpkt->length = 0;
/* Send the request to the local ticket-granting server */
if (kerror = send_to_kdc(pkt, rpkt, realm)) return(kerror);
/* check packet version of the returned packet */
if (pkt_version(rpkt) != KRB_PROT_VERSION )
return(INTK_PROT);
/* Check byte order */
msg_byte_order = pkt_msg_type(rpkt) & 1;
swap_bytes = 0;
if (msg_byte_order != HOST_BYTE_ORDER)
swap_bytes++;
/* This used to be
switch (pkt_msg_type(rpkt) & ~1) {
but SCO 3.2v4 cc compiled that incorrectly. */
t_switch = pkt_msg_type(rpkt);
t_switch &= ~1;
switch (t_switch) {
case AUTH_MSG_KDC_REPLY:
break;
case AUTH_MSG_ERR_REPLY:
memcpy((char *) &rep_err_code, pkt_err_code(rpkt), 4);
if (swap_bytes)
rep_err_code = krb4_swab32(rep_err_code);
return(rep_err_code);
default:
return(INTK_PROT);
}
/* Extract the ciphertext */
cip->length = pkt_clen(rpkt); /* let clen do the swap */
memcpy((char *) (cip->dat), (char *) pkt_cipher(rpkt), cip->length);
#ifndef NOENCRYPTION
/* Attempt to decrypt it */
key_sched(cr.session,key_s);
DEB (("About to do decryption ..."));
pcbc_encrypt((C_Block *)cip->dat,(C_Block *)cip->dat,
(long) cip->length,key_s,(C_Block *)cr.session,0);
#endif /* !NOENCRYPTION */
/* Get rid of all traces of key */
memset((char *) cr.session, 0, sizeof(cr.session));
memset((char *) key_s, 0, sizeof(key_s));
ptr = (char *) cip->dat;
memcpy((char *)ses, ptr, 8);
ptr += 8;
(void) strcpy(s_name,ptr);
ptr += strlen(s_name) + 1;
(void) strcpy(s_instance,ptr);
ptr += strlen(s_instance) + 1;
(void) strcpy(rlm,ptr);
ptr += strlen(rlm) + 1;
lifetime = (unsigned long) ptr[0];
kvno = (unsigned long) ptr[1];
tkt->length = (int) ptr[2];
ptr += 3;
memcpy((char *)(tkt->dat), ptr, tkt->length);
ptr += tkt->length;
if (strcmp(s_name, service) || strcmp(s_instance, sinstance) ||
strcmp(rlm, realm)) /* not what we asked for */
return(INTK_ERR); /* we need a better code here XXX */
/* check KDC time stamp */
memcpy((char *)&kdc_time, ptr, 4); /* Time (coarse) */
if (swap_bytes) kdc_time = krb4_swab32(kdc_time);
ptr += 4;
t_local = TIME_GMT_UNIXSEC;
t_diff = t_local - kdc_time;
if (t_diff < 0) t_diff = -t_diff; /* Absolute value of difference */
if (t_diff > CLOCK_SKEW) {
return(RD_AP_TIME); /* XXX should probably be better
code */
}
if (kerror = krb_save_credentials(s_name,s_instance,rlm,ses,lifetime,
kvno,tkt,t_local))
return(kerror);
return(AD_OK);
}
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