4.4BSD/usr/src/kerberosIV/krb/recvauth.c
/*
* $Source: /usr/src/kerberosIV/src/lib/krb/RCS/recvauth.c,v $
* $Author: kfall $
*
* Copyright 1987, 1988 by the Massachusetts Institute of Technology.
*
* For copying and distribution information, please see the file
* <mit-copyright.h>.
*/
#ifndef lint
static char rcsid_recvauth_c[] =
"$Header: /usr/src/kerberosIV/src/lib/krb/RCS/recvauth.c,v 4.4 90/05/12 00:58:56 kfall Exp $";
#endif lint
#include <mit-copyright.h>
#include <des.h>
#include <krb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <syslog.h>
#include <errno.h>
#include <stdio.h>
#include <strings.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_sendauth.c
* be sure to support old versions of krb_sendauth!
*/
extern int errno;
/*
* krb_recvauth() reads (and optionally responds to) a message sent
* using krb_sendauth(). The "options" argument is a bit-field of
* selected options (see "sendauth.c" for options description).
* The only option relevant to krb_recvauth() is KOPT_DO_MUTUAL
* (mutual authentication requested). The "fd" argument supplies
* a file descriptor to read from (and write to, if mutual authenti-
* cation is requested).
*
* Part of the received message will be a Kerberos ticket sent by the
* client; this is read into the "ticket" argument. The "service" and
* "instance" arguments supply the server's Kerberos name. If the
* "instance" argument is the string "*", it is treated as a wild card
* and filled in during the krb_rd_req() call (see read_service_key()).
*
* The "faddr" and "laddr" give the sending (client) and receiving
* (local server) network addresses. ("laddr" may be left NULL unless
* mutual authentication is requested, in which case it must be set.)
*
* The authentication information extracted from the message is returned
* in "kdata". The "filename" argument indicates the file where the
* server's key can be found. (It is passed on to krb_rd_req().) If
* left null, the default "/etc/srvtab" will be used.
*
* If mutual authentication is requested, the session key schedule must
* be computed in order to reply; this schedule is returned in the
* "schedule" argument. A string containing the application version
* number from the received message is returned in "version", which
* should be large enough to hold a KRB_SENDAUTH_VLEN-character string.
*
* See krb_sendauth() for the format of the received client message.
*
* This routine supports another client format, for backward
* compatibility, consisting of:
*
* Size Variable Field
* ---- -------- -----
*
* string tmp_buf, tkt_len length of ticket, in
* ascii
*
* char ' ' (space char) separator
*
* tkt_len ticket->dat the ticket
*
* This old-style version does not support mutual authentication.
*
* krb_recvauth() first reads the protocol version string from the
* given file descriptor. If it doesn't match the current protocol
* version (KRB_SENDAUTH_VERS), the old-style format is assumed. In
* that case, the string of characters up to the first space is read
* and interpreted as the ticket length, then the ticket is read.
*
* If the first string did match KRB_SENDAUTH_VERS, krb_recvauth()
* next reads the application protocol version string. Then the
* ticket length and ticket itself are read.
*
* The ticket is decrypted and checked by the call to krb_rd_req().
* If no mutual authentication is required, the result of the
* krb_rd_req() call is retured by this routine. If mutual authenti-
* cation is required, a message in the following format is returned
* on "fd":
*
* Size Variable Field
* ---- -------- -----
*
* 4 bytes tkt_len length of ticket or -1
* if error occurred
*
* priv_len tmp_buf "private" message created
* by krb_mk_priv() which
* contains the incremented
* checksum sent by the client
* encrypted in the session
* key. (This field is not
* present in case of error.)
*
* If all goes well, KSUCCESS is returned; otherwise KFAILURE or some
* other error code is returned.
*/
int
krb_recvauth(options, fd, ticket, service, instance, faddr, laddr, kdata,
filename, schedule, version)
long options; /* bit-pattern of options */
int fd; /* file descr. to read from */
KTEXT ticket; /* storage for client's ticket */
char *service; /* service expected */
char *instance; /* inst expected (may be filled in) */
struct sockaddr_in *faddr; /* address of foreign host on fd */
struct sockaddr_in *laddr; /* local address */
AUTH_DAT *kdata; /* kerberos data (returned) */
char *filename; /* name of file with service keys */
Key_schedule schedule; /* key schedule (return) */
char *version; /* version string (filled in) */
{
int i, cc, old_vers = 0;
char krb_vers[KRB_SENDAUTH_VLEN + 1]; /* + 1 for the null terminator */
char *cp;
int rem;
long tkt_len, priv_len;
u_long cksum;
u_char tmp_buf[1024];
/* read the protocol version number */
if (krb_net_read(fd, krb_vers, KRB_SENDAUTH_VLEN) !=
KRB_SENDAUTH_VLEN)
return(errno);
krb_vers[KRB_SENDAUTH_VLEN] = '\0';
/* check version string */
if (strcmp(krb_vers,KRB_SENDAUTH_VERS)) {
/* Assume the old version of sendkerberosdata: send ascii
length, ' ', and ticket. */
if (options & KOPT_DO_MUTUAL)
return(KFAILURE); /* XXX can't do old style with mutual auth */
old_vers = 1;
/* copy what we have read into tmp_buf */
(void) bcopy(krb_vers, (char *) tmp_buf, KRB_SENDAUTH_VLEN);
/* search for space, and make it a null */
for (i = 0; i < KRB_SENDAUTH_VLEN; i++)
if (tmp_buf[i]== ' ') {
tmp_buf[i] = '\0';
/* point cp to the beginning of the real ticket */
cp = (char *) &tmp_buf[i+1];
break;
}
if (i == KRB_SENDAUTH_VLEN)
/* didn't find the space, keep reading to find it */
for (; i<20; i++) {
if (read(fd, (char *)&tmp_buf[i], 1) != 1) {
return(KFAILURE);
}
if (tmp_buf[i] == ' ') {
tmp_buf[i] = '\0';
/* point cp to the beginning of the real ticket */
cp = (char *) &tmp_buf[i+1];
break;
}
}
tkt_len = (long) atoi((char *) tmp_buf);
/* sanity check the length */
if ((i==20)||(tkt_len<=0)||(tkt_len>MAX_KTXT_LEN))
return(KFAILURE);
if (i < KRB_SENDAUTH_VLEN) {
/* since we already got the space, and part of the ticket,
we read fewer bytes to get the rest of the ticket */
if (krb_net_read(fd, (char *)(tmp_buf+KRB_SENDAUTH_VLEN),
(int) (tkt_len - KRB_SENDAUTH_VLEN + 1 + i))
!= (int)(tkt_len - KRB_SENDAUTH_VLEN + 1 + i))
return(errno);
} else {
if (krb_net_read(fd, (char *)(tmp_buf+i), (int)tkt_len) !=
(int) tkt_len)
return(errno);
}
ticket->length = tkt_len;
/* copy the ticket into the struct */
(void) bcopy(cp, (char *) ticket->dat, ticket->length);
} else {
/* read the application version string */
if (krb_net_read(fd, version, KRB_SENDAUTH_VLEN) !=
KRB_SENDAUTH_VLEN)
return(errno);
version[KRB_SENDAUTH_VLEN] = '\0';
/* get the length of the ticket */
if (krb_net_read(fd, (char *)&tkt_len, sizeof(tkt_len)) !=
sizeof(tkt_len))
return(errno);
/* sanity check */
ticket->length = ntohl((unsigned long)tkt_len);
if ((ticket->length <= 0) || (ticket->length > MAX_KTXT_LEN)) {
if (options & KOPT_DO_MUTUAL) {
rem = KFAILURE;
goto mutual_fail;
} else
return(KFAILURE); /* XXX there may still be junk on the fd? */
}
/* read the ticket */
if (krb_net_read(fd, (char *) ticket->dat, ticket->length)
!= ticket->length)
return(errno);
}
/*
* now have the ticket. decrypt it to get the authenticated
* data.
*/
rem = krb_rd_req(ticket,service,instance,faddr->sin_addr.s_addr,
kdata,filename);
if (old_vers) return(rem); /* XXX can't do mutual with old client */
/* if we are doing mutual auth, compose a response */
if (options & KOPT_DO_MUTUAL) {
if (rem != KSUCCESS)
/* the krb_rd_req failed */
goto mutual_fail;
/* add one to the (formerly) sealed checksum, and re-seal it
for return to the client */
cksum = kdata->checksum + 1;
cksum = htonl(cksum);
#ifndef NOENCRYPTION
key_sched(kdata->session,schedule);
#endif /* !NOENCRYPTION */
priv_len = krb_mk_priv((unsigned char *)&cksum,
tmp_buf,
(unsigned long) sizeof(cksum),
schedule,
kdata->session,
laddr,
faddr);
if (priv_len < 0) {
/* re-sealing failed; notify the client */
rem = KFAILURE; /* XXX */
mutual_fail:
priv_len = -1;
tkt_len = htonl((unsigned long) priv_len);
/* a length of -1 is interpreted as an authentication
failure by the client */
if ((cc = krb_net_write(fd, (char *)&tkt_len, sizeof(tkt_len)))
!= sizeof(tkt_len))
return(cc);
return(rem);
} else {
/* re-sealing succeeded, send the private message */
tkt_len = htonl((unsigned long)priv_len);
if ((cc = krb_net_write(fd, (char *)&tkt_len, sizeof(tkt_len)))
!= sizeof(tkt_len))
return(cc);
if ((cc = krb_net_write(fd, (char *)tmp_buf, (int) priv_len))
!= (int) priv_len)
return(cc);
}
}
return(rem);
}