NetBSD-5.0.2/usr.bin/login/k5login.c
/* $NetBSD: k5login.c,v 1.27 2006/03/23 23:33:28 wiz Exp $ */
/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* Copyright (c) 1980, 1987, 1988 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley. The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)klogin.c 5.11 (Berkeley) 7/12/92";
#endif
__RCSID("$NetBSD: k5login.c,v 1.27 2006/03/23 23:33:28 wiz Exp $");
#endif /* not lint */
#ifdef KERBEROS5
#include <sys/param.h>
#include <sys/syslog.h>
#include <krb5/krb5.h>
#include <pwd.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#define KRB5_DEFAULT_OPTIONS 0
#define KRB5_DEFAULT_LIFE 60*60*10 /* 10 hours */
krb5_context kcontext;
int notickets;
int krb5_configured;
char *krb5tkfile_env;
extern char *tty;
extern int login_krb5_forwardable_tgt;
extern int has_ccache;
static char tkt_location[MAXPATHLEN];
static krb5_creds forw_creds;
int have_forward;
static krb5_principal me, server;
int k5_read_creds(char *);
int k5_write_creds(void);
int k5_verify_creds(krb5_context, krb5_ccache);
int k5login(struct passwd *, char *, char *, char *);
void k5destroy(void);
#ifndef krb5_realm_length
#define krb5_realm_length(r) ((r).length)
#endif
#ifndef krb5_realm_data
#define krb5_realm_data(r) ((r).data)
#endif
/*
* Verify the Kerberos ticket-granting ticket just retrieved for the
* user. If the Kerberos server doesn't respond, assume the user is
* trying to fake us out (since we DID just get a TGT from what is
* supposedly our KDC). If the host/<host> service is unknown (i.e.,
* the local keytab doesn't have it), let her in.
*
* Returns 1 for confirmation, -1 for failure, 0 for uncertainty.
*/
int
k5_verify_creds(krb5_context c, krb5_ccache ccache)
{
char phost[MAXHOSTNAMELEN];
int retval, have_keys;
krb5_principal princ;
krb5_keyblock *kb = 0;
krb5_error_code kerror;
krb5_data packet;
krb5_auth_context auth_context = NULL;
krb5_ticket *ticket = NULL;
kerror = krb5_sname_to_principal(c, 0, 0, KRB5_NT_SRV_HST, &princ);
if (kerror) {
krb5_warn(kcontext, kerror, "constructing local service name");
return (-1);
}
/* Do we have host/<host> keys? */
/* (use default keytab, kvno IGNORE_VNO to get the first match,
* and default enctype.) */
kerror = krb5_kt_read_service_key(c, NULL, princ, 0, 0, &kb);
if (kb)
krb5_free_keyblock(c, kb);
/* any failure means we don't have keys at all. */
have_keys = kerror ? 0 : 1;
/* XXX there should be a krb5 function like mk_req, but taking a full
* principal, instead of a service/hostname. (Did I miss one?) */
gethostname(phost, sizeof(phost));
phost[sizeof(phost) - 1] = '\0';
/* talk to the kdc and construct the ticket */
kerror = krb5_mk_req(c, &auth_context, 0, "host", phost,
0, ccache, &packet);
/* wipe the auth context for rd_req */
if (auth_context) {
krb5_auth_con_free(c, auth_context);
auth_context = NULL;
}
if (kerror == KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN) {
/* we have a service key, so something should be
* in the database, therefore this error packet could
* have come from an attacker. */
if (have_keys) {
retval = -1;
goto EGRESS;
}
/* but if it is unknown and we've got no key, we don't
* have any security anyhow, so it is ok. */
else {
retval = 0;
goto EGRESS;
}
}
else if (kerror) {
krb5_warn(kcontext, kerror,
"Unable to verify Kerberos V5 TGT: %s", phost);
syslog(LOG_NOTICE, "Kerberos V5 TGT bad: %s",
krb5_get_err_text(kcontext, kerror));
retval = -1;
goto EGRESS;
}
/* got ticket, try to use it */
kerror = krb5_rd_req(c, &auth_context, &packet,
princ, NULL, NULL, &ticket);
if (kerror) {
if (!have_keys) {
/* The krb5 errors aren't specified well, but I think
* these values cover the cases we expect. */
switch (kerror) {
case ENOENT: /* no keytab */
case KRB5_KT_NOTFOUND:
retval = 0;
break;
default:
/* unexpected error: fail */
retval = -1;
break;
}
}
else {
/* we have keys, so if we got any error, we could be
* under attack. */
retval = -1;
}
krb5_warn(kcontext, kerror, "Unable to verify host ticket");
syslog(LOG_NOTICE, "can't verify v5 ticket: %s; %s\n",
krb5_get_err_text(kcontext, kerror),
retval
? "keytab found, assuming failure"
: "no keytab found, assuming success");
goto EGRESS;
}
/*
* The host/<host> ticket has been received _and_ verified.
*/
retval = 1;
/* do cleanup and return */
EGRESS:
if (auth_context)
krb5_auth_con_free(c, auth_context);
krb5_free_principal(c, princ);
/* possibly ticket and packet need freeing here as well */
return (retval);
}
/*
* Attempt to read forwarded kerberos creds
*
* return 0 on success (forwarded creds in memory)
* 1 if no forwarded creds.
*/
int
k5_read_creds(char *username)
{
krb5_error_code kerror;
krb5_creds mcreds;
krb5_ccache ccache;
have_forward = 0;
memset((char*) &mcreds, 0, sizeof(forw_creds));
memset((char*) &forw_creds, 0, sizeof(forw_creds));
kerror = krb5_cc_default(kcontext, &ccache);
if (kerror) {
krb5_warn(kcontext, kerror, "while getting default ccache");
return(1);
}
kerror = krb5_parse_name(kcontext, username, &me);
if (kerror) {
krb5_warn(kcontext, kerror, "when parsing name %s", username);
return(1);
}
mcreds.client = me;
kerror = krb5_build_principal_ext(kcontext, &mcreds.server,
krb5_realm_length(*krb5_princ_realm(kcontext, me)),
krb5_realm_data(*krb5_princ_realm(kcontext, me)),
KRB5_TGS_NAME_SIZE,
KRB5_TGS_NAME,
krb5_realm_length(*krb5_princ_realm(kcontext, me)),
krb5_realm_data(*krb5_princ_realm(kcontext, me)),
0);
if (kerror) {
krb5_warn(kcontext, kerror, "while building server name");
goto nuke_ccache;
}
kerror = krb5_cc_retrieve_cred(kcontext, ccache, 0,
&mcreds, &forw_creds);
if (kerror) {
krb5_warn(kcontext, kerror,
"while retrieving V5 initial ticket for copy");
goto nuke_ccache;
}
have_forward = 1;
strlcpy(tkt_location, getenv("KRB5CCNAME"), sizeof(tkt_location));
krb5tkfile_env = tkt_location;
has_ccache = 1;
notickets = 0;
nuke_ccache:
krb5_cc_destroy(kcontext, ccache);
return(!have_forward);
}
int
k5_write_creds(void)
{
krb5_error_code kerror;
krb5_ccache ccache;
if (!have_forward)
return (1);
kerror = krb5_cc_default(kcontext, &ccache);
if (kerror) {
krb5_warn(kcontext, kerror, "while getting default ccache");
return (1);
}
kerror = krb5_cc_initialize(kcontext, ccache, me);
if (kerror) {
krb5_warn(kcontext, kerror,
"while re-initializing V5 ccache as user");
goto nuke_ccache_contents;
}
kerror = krb5_cc_store_cred(kcontext, ccache, &forw_creds);
if (kerror) {
krb5_warn(kcontext, kerror,
"while re-storing V5 ccache as user");
goto nuke_ccache_contents;
}
nuke_ccache_contents:
krb5_free_cred_contents(kcontext, &forw_creds);
return (kerror != 0);
}
/*
* Attempt to log the user in using Kerberos authentication
*
* return 0 on success (will be logged in)
* 1 if Kerberos failed (try local password in login)
*/
int
k5login(struct passwd *pw, char *instance, char *localhost, char *password)
{
krb5_error_code kerror;
krb5_creds my_creds;
krb5_timestamp now;
krb5_ccache ccache = NULL;
long lifetime = KRB5_DEFAULT_LIFE;
int options = KRB5_DEFAULT_OPTIONS;
char *realm, *client_name;
char *principal;
krb5_configured = 1;
if (login_krb5_forwardable_tgt)
options |= KDC_OPT_FORWARDABLE;
/*
* Root logins don't use Kerberos.
* If we have a realm, try getting a ticket-granting ticket
* and using it to authenticate. Otherwise, return
* failure so that we can try the normal passwd file
* for a password. If that's ok, log the user in
* without issuing any tickets.
*/
if (strcmp(pw->pw_name, "root") == 0 ||
krb5_get_default_realm(kcontext, &realm)) {
krb5_configured = 0;
return (1);
}
/*
* get TGT for local realm
* tickets are stored in a file named TKT_ROOT plus uid
* except for user.root tickets.
*/
if (strcmp(instance, "root") != 0)
(void)snprintf(tkt_location, sizeof tkt_location,
"FILE:/tmp/krb5cc_%d.%s", pw->pw_uid, tty);
else
(void)snprintf(tkt_location, sizeof tkt_location,
"FILE:/tmp/krb5cc_root_%d.%s", pw->pw_uid, tty);
krb5tkfile_env = tkt_location;
has_ccache = 1;
if (strlen(instance))
asprintf(&principal, "%s/%s", pw->pw_name, instance);
else
principal = strdup(pw->pw_name);
if (!principal) {
syslog(LOG_NOTICE, "fatal: %s", strerror(errno));
return (1);
}
if ((kerror = krb5_cc_resolve(kcontext, tkt_location, &ccache)) != 0) {
syslog(LOG_NOTICE, "warning: %s while getting default ccache",
krb5_get_err_text(kcontext, kerror));
return (1);
}
if ((kerror = krb5_parse_name(kcontext, principal, &me)) != 0) {
syslog(LOG_NOTICE, "warning: %s when parsing name %s",
krb5_get_err_text(kcontext, kerror), principal);
return (1);
}
if ((kerror = krb5_unparse_name(kcontext, me, &client_name)) != 0) {
syslog(LOG_NOTICE, "warning: %s when unparsing name %s",
krb5_get_err_text(kcontext, kerror), principal);
return (1);
}
kerror = krb5_cc_initialize(kcontext, ccache, me);
if (kerror != 0) {
syslog(LOG_NOTICE, "%s when initializing cache %s",
krb5_get_err_text(kcontext, kerror), tkt_location);
return (1);
}
memset((char *)&my_creds, 0, sizeof(my_creds));
my_creds.client = me;
if ((kerror = krb5_build_principal_ext(kcontext,
&server,
krb5_realm_length(*krb5_princ_realm(kcontext, me)),
krb5_realm_data(*krb5_princ_realm(kcontext, me)),
KRB5_TGS_NAME_SIZE,
KRB5_TGS_NAME,
krb5_realm_length(*krb5_princ_realm(kcontext, me)),
krb5_realm_data(*krb5_princ_realm(kcontext, me)),
0)) != 0) {
syslog(LOG_NOTICE, "%s while building server name",
krb5_get_err_text(kcontext, kerror));
return (1);
}
my_creds.server = server;
if ((kerror = krb5_timeofday(kcontext, &now)) != 0) {
syslog(LOG_NOTICE, "%s while getting time of day",
krb5_get_err_text(kcontext, kerror));
return (1);
}
my_creds.times.starttime = 0; /* start timer when request
gets to KDC */
my_creds.times.endtime = now + lifetime;
my_creds.times.renew_till = 0;
kerror = krb5_get_in_tkt_with_password(kcontext, options,
NULL,
NULL,
NULL,
password,
ccache,
&my_creds, 0);
if (my_creds.server != NULL)
krb5_free_principal(kcontext, my_creds.server);
if (chown(&tkt_location[5], pw->pw_uid, pw->pw_gid) < 0)
syslog(LOG_ERR, "chown tkfile (%s): %m", &tkt_location[5]);
if (kerror) {
if (kerror == KRB5KRB_AP_ERR_BAD_INTEGRITY)
printf("%s: Kerberos Password incorrect\n", principal);
else
krb5_warn(kcontext, kerror,
"while getting initial credentials");
return (1);
}
if (k5_verify_creds(kcontext, ccache) < 0)
return (1);
/* Success */
notickets = 0;
return (0);
}
/*
* Remove any credentials
*/
void
k5destroy(void)
{
krb5_error_code kerror;
krb5_ccache ccache = NULL;
if (krb5tkfile_env == NULL)
return;
kerror = krb5_cc_resolve(kcontext, krb5tkfile_env, &ccache);
if (kerror == 0)
(void)krb5_cc_destroy(kcontext, ccache);
}
#endif /* KERBEROS5 */