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/*
auth-kerberos.c
Dug Song <dugsong@UMICH.EDU>
Kerberos v4 authentication and ticket-passing routines.
$Id: auth-krb4.c,v 1.5 1999/11/02 19:10:14 markus Exp $
*/
#include "includes.h"
#include "packet.h"
#include "xmalloc.h"
#include "ssh.h"
#ifdef KRB4
int ssh_tf_init(uid_t uid)
{
extern char *ticket;
char *tkt_root = TKT_ROOT;
struct stat st;
int fd;
/* Set unique ticket string manually since we're still root. */
ticket = xmalloc(MAXPATHLEN);
#ifdef AFS
if (lstat("/ticket", &st) != -1)
tkt_root = "/ticket/";
#endif /* AFS */
snprintf(ticket, MAXPATHLEN, "%s%d_%d", tkt_root, uid, getpid());
(void) krb_set_tkt_string(ticket);
/* Make sure we own this ticket file, and we created it. */
if (lstat(ticket, &st) == -1 && errno == ENOENT) {
/* good, no ticket file exists. create it. */
if ((fd = open(ticket, O_RDWR|O_CREAT|O_EXCL, 0600)) != -1) {
close(fd);
return 1;
}
}
else {
/* file exists. make sure server_user owns it (e.g. just passed ticket),
and that it isn't a symlink, and that it is mode 600. */
if (st.st_mode == (S_IFREG|S_IRUSR|S_IWUSR) && st.st_uid == uid)
return 1;
}
/* Failure. */
log("WARNING: bad ticket file %s", ticket);
return 0;
}
int auth_krb4(const char *server_user, KTEXT auth, char **client)
{
AUTH_DAT adat = { 0 };
KTEXT_ST reply;
char instance[INST_SZ];
int r, s;
u_int cksum;
Key_schedule schedule;
struct sockaddr_in local, foreign;
s = packet_get_connection_in();
r = sizeof(local);
memset(&local, 0, sizeof(local));
if (getsockname(s, (struct sockaddr *) &local, &r) < 0)
debug("getsockname failed: %.100s", strerror(errno));
r = sizeof(foreign);
memset(&foreign, 0, sizeof(foreign));
if (getpeername(s, (struct sockaddr *)&foreign, &r) < 0)
debug("getpeername failed: %.100s", strerror(errno));
instance[0] = '*'; instance[1] = 0;
/* Get the encrypted request, challenge, and session key. */
if ((r = krb_rd_req(auth, KRB4_SERVICE_NAME, instance, 0, &adat, ""))) {
packet_send_debug("Kerberos V4 krb_rd_req: %.100s", krb_err_txt[r]);
return 0;
}
des_key_sched((des_cblock *)adat.session, schedule);
*client = xmalloc(MAX_K_NAME_SZ);
(void) snprintf(*client, MAX_K_NAME_SZ, "%s%s%s@%s", adat.pname,
*adat.pinst ? "." : "", adat.pinst, adat.prealm);
/* Check ~/.klogin authorization now. */
if (kuserok(&adat, (char *)server_user) != KSUCCESS) {
packet_send_debug("Kerberos V4 .klogin authorization failed!");
log("Kerberos V4 .klogin authorization failed for %s to account %s",
*client, server_user);
return 0;
}
/* Increment the checksum, and return it encrypted with the session key. */
cksum = adat.checksum + 1;
cksum = htonl(cksum);
/* If we can't successfully encrypt the checksum, we send back an empty
message, admitting our failure. */
if ((r = krb_mk_priv((u_char *)&cksum, reply.dat, sizeof(cksum)+1,
schedule, &adat.session, &local, &foreign)) < 0) {
packet_send_debug("Kerberos V4 mk_priv: (%d) %s", r, krb_err_txt[r]);
reply.dat[0] = 0;
reply.length = 0;
}
else
reply.length = r;
/* Clear session key. */
memset(&adat.session, 0, sizeof(&adat.session));
packet_start(SSH_SMSG_AUTH_KERBEROS_RESPONSE);
packet_put_string((char *) reply.dat, reply.length);
packet_send();
packet_write_wait();
return 1;
}
#endif /* KRB4 */
#ifdef AFS
int auth_kerberos_tgt(struct passwd *pw, const char *string)
{
CREDENTIALS creds;
extern char *ticket;
int r;
if (!radix_to_creds(string, &creds)) {
log("Protocol error decoding Kerberos V4 tgt");
packet_send_debug("Protocol error decoding Kerberos V4 tgt");
goto auth_kerberos_tgt_failure;
}
if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
strlcpy(creds.service, "krbtgt", sizeof creds.service);
if (strcmp(creds.service, "krbtgt")) {
log("Kerberos V4 tgt (%s%s%s@%s) rejected for uid %d",
creds.pname, creds.pinst[0] ? "." : "", creds.pinst, creds.realm,
pw->pw_uid);
packet_send_debug("Kerberos V4 tgt (%s%s%s@%s) rejected for uid %d",
creds.pname, creds.pinst[0] ? "." : "", creds.pinst,
creds.realm, pw->pw_uid);
goto auth_kerberos_tgt_failure;
}
if (!ssh_tf_init(pw->pw_uid) ||
(r = in_tkt(creds.pname, creds.pinst)) ||
(r = save_credentials(creds.service, creds.instance, creds.realm,
creds.session, creds.lifetime, creds.kvno,
&creds.ticket_st, creds.issue_date))) {
xfree(ticket);
ticket = NULL;
packet_send_debug("Kerberos V4 tgt refused: couldn't save credentials");
goto auth_kerberos_tgt_failure;
}
/* Successful authentication, passed all checks. */
chown(ticket, pw->pw_uid, pw->pw_gid);
packet_send_debug("Kerberos V4 tgt accepted (%s.%s@%s, %s%s%s@%s)",
creds.service, creds.instance, creds.realm,
creds.pname, creds.pinst[0] ? "." : "",
creds.pinst, creds.realm);
packet_start(SSH_SMSG_SUCCESS);
packet_send();
packet_write_wait();
return 1;
auth_kerberos_tgt_failure:
memset(&creds, 0, sizeof(creds));
packet_start(SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
return 0;
}
int auth_afs_token(struct passwd *pw, const char *token_string)
{
CREDENTIALS creds;
uid_t uid = pw->pw_uid;
if (!radix_to_creds(token_string, &creds)) {
log("Protocol error decoding AFS token");
packet_send_debug("Protocol error decoding AFS token");
packet_start(SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
return 0;
}
if (strncmp(creds.service, "", 1) == 0) /* backward compatibility */
strlcpy(creds.service, "afs", sizeof creds.service);
if (strncmp(creds.pname, "AFS ID ", 7) == 0)
uid = atoi(creds.pname + 7);
if (kafs_settoken(creds.realm, uid, &creds)) {
log("AFS token (%s@%s) rejected for uid %d", creds.pname,
creds.realm, uid);
packet_send_debug("AFS token (%s@%s) rejected for uid %d", creds.pname,
creds.realm, uid);
packet_start(SSH_SMSG_FAILURE);
packet_send();
packet_write_wait();
return 0;
}
packet_send_debug("AFS token accepted (%s@%s, %s@%s)", creds.service,
creds.realm, creds.pname, creds.realm);
packet_start(SSH_SMSG_SUCCESS);
packet_send();
packet_write_wait();
return 1;
}
#endif /* AFS */
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