[gssapi-openssh.git] / openssh / gss-serv-krb5.c

/*	$OpenBSD: gss-serv-krb5.c,v 1.3 2004/07/21 10:36:23 djm Exp $	*/

/*
 * Copyright (c) 2001-2003 Simon Wilkinson. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `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 AUTHOR 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.
 */

#include "includes.h"

#ifdef GSSAPI
#ifdef KRB5

#include "auth.h"
#include "xmalloc.h"
#include "log.h"
#include "servconf.h"

#include "ssh-gss.h"

extern ServerOptions options;

#ifdef HEIMDAL
# include <krb5.h>
#else
# ifdef HAVE_GSSAPI_KRB5
#  include <gssapi_krb5.h>
# elif HAVE_GSSAPI_GSSAPI_KRB5
#  include <gssapi/gssapi_krb5.h>
# endif
#endif

static krb5_context krb_context = NULL;
static int ssh_gssapi_krb5_init();
static int ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name);
static int ssh_gssapi_krb5_localname(ssh_gssapi_client *client, char **user);
static void ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client);

ssh_gssapi_mech gssapi_kerberos_mech = {
	"toWM5Slw5Ew8Mqkay+al2g==",
	"Kerberos",
	{9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
	NULL,
	&ssh_gssapi_krb5_userok,
	&ssh_gssapi_krb5_localname,
	&ssh_gssapi_krb5_storecreds
};

ssh_gssapi_mech gssapi_kerberos_mech_old = {
	"Se3H81ismmOC3OE+FwYCiQ==",
	"Kerberos",
	{9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
	&ssh_gssapi_krb5_init,
	&ssh_gssapi_krb5_userok,
	&ssh_gssapi_krb5_localname,
	&ssh_gssapi_krb5_storecreds
};

/* Initialise the krb5 library, for the stuff that GSSAPI won't do */

static int
ssh_gssapi_krb5_init(void)
{
	krb5_error_code problem;

	if (krb_context != NULL)
		return 1;

	problem = krb5_init_context(&krb_context);
	if (problem) {
		logit("Cannot initialize krb5 context");
		return 0;
	}
#ifdef KRB5_INIT_ETS
	krb5_init_ets(krb_context);
#endif

	return 1;
}

/* Check if this user is OK to login. This only works with krb5 - other
 * GSSAPI mechanisms will need their own.
 * Returns true if the user is OK to log in, otherwise returns 0
 */

static int
ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name)
{
	krb5_principal princ;
	int retval;

	if (ssh_gssapi_krb5_init() == 0)
		return 0;

	if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
	    &princ))) {
		logit("krb5_parse_name(): %.100s",
		    krb5_get_err_text(krb_context, retval));
		return 0;
	}
	if (krb5_kuserok(krb_context, princ, name)) {
		retval = 1;
		logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
		    name, (char *)client->displayname.value);
	} else
		retval = 0;

	krb5_free_principal(krb_context, princ);
	return retval;
}


/* Retrieve the local username associated with a set of Kerberos 
 * credentials. Hopefully we can use this for the 'empty' username
 * logins discussed in the draft  */
static int
ssh_gssapi_krb5_localname(ssh_gssapi_client *client, char **user) {
	krb5_principal princ;
	int retval;
	
	if (ssh_gssapi_krb5_init() == 0)
		return 0;

	if ((retval=krb5_parse_name(krb_context, client->displayname.value, 
				    &princ))) {
		logit("krb5_parse_name(): %.100s", 
			krb5_get_err_text(krb_context,retval));
		return 0;
	}
	
	/* We've got to return a malloc'd string */
	*user = (char *)xmalloc(256);
	if (krb5_aname_to_localname(krb_context, princ, 256, *user)) {
		xfree(*user);
		*user = NULL;
		return(0);
	}
	
	return(1);
}
	
/* This writes out any forwarded credentials from the structure populated
 * during userauth. Called after we have setuid to the user */

static void
ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
{
	krb5_ccache ccache;
	krb5_error_code problem;
	krb5_principal princ;
	OM_uint32 maj_status, min_status;
	gss_cred_id_t krb5_cred_handle;
	int len;

	if (client->creds == NULL) {
		debug("No credentials stored");
		return;
	}

	if (ssh_gssapi_krb5_init() == 0)
		return;

#ifdef HEIMDAL
	if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
		logit("krb5_cc_gen_new(): %.100s",
		    krb5_get_err_text(krb_context, problem));
		return;
	}
#else
	{
		int tmpfd;
		char ccname[40];
		mode_t old_umask;

		snprintf(ccname, sizeof(ccname),
		    "FILE:/tmp/krb5cc_%d_XXXXXX", geteuid());

		old_umask = umask(0177);
		tmpfd = mkstemp(ccname + strlen("FILE:"));
		umask(old_umask);
		if (tmpfd == -1) {
			logit("mkstemp(): %.100s", strerror(errno));
			problem = errno;
			return;
		}
		if (fchmod(tmpfd, S_IRUSR | S_IWUSR) == -1) {
			logit("fchmod(): %.100s", strerror(errno));
			close(tmpfd);
			problem = errno;
			return;
		}
		close(tmpfd);
		if ((problem = krb5_cc_resolve(krb_context, ccname, &ccache))) {
			logit("krb5_cc_resolve(): %.100s",
			    krb5_get_err_text(krb_context, problem));
			return;
		}
	}
#endif	/* #ifdef HEIMDAL */

	if ((problem = krb5_parse_name(krb_context,
	    client->exportedname.value, &princ))) {
		logit("krb5_parse_name(): %.100s",
		    krb5_get_err_text(krb_context, problem));
		krb5_cc_destroy(krb_context, ccache);
		return;
	}

	if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
		logit("krb5_cc_initialize(): %.100s",
		    krb5_get_err_text(krb_context, problem));
		krb5_free_principal(krb_context, princ);
		krb5_cc_destroy(krb_context, ccache);
		return;
	}

	krb5_free_principal(krb_context, princ);

#ifdef MECHGLUE
	krb5_cred_handle =
	    __gss_get_mechanism_cred(client->creds,
				     &(gssapi_kerberos_mech.oid));
#else
	krb5_cred_handle = client->creds;
#endif

	if ((maj_status = gss_krb5_copy_ccache(&min_status, 
	    krb5_cred_handle, ccache))) {
		logit("gss_krb5_copy_ccache() failed");
		krb5_cc_destroy(krb_context, ccache);
		return;
	}

	client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
	client->store.envvar = "KRB5CCNAME";
	len = strlen(client->store.filename) + 6;
	client->store.envval = xmalloc(len);
	snprintf(client->store.envval, len, "FILE:%s", client->store.filename);

#ifdef USE_PAM
	if (options.use_pam)
		do_pam_putenv(client->store.envvar, client->store.envval);
#endif

	krb5_cc_close(krb_context, ccache);

	return;
}

#endif /* KRB5 */

#endif /* GSSAPI */
Commit	Line	Data
1b56ff3d	1	/* $OpenBSD: gss-serv-krb5.c,v 1.3 2004/07/21 10:36:23 djm Exp $ */
70791e56	2
88928908	3	/*
	4	* Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
	5	*
	6	* Redistribution and use in source and binary forms, with or without
	7	* modification, are permitted provided that the following conditions
	8	* are met:
	9	* 1. Redistributions of source code must retain the above copyright
	10	* notice, this list of conditions and the following disclaimer.
	11	* 2. Redistributions in binary form must reproduce the above copyright
	12	* notice, this list of conditions and the following disclaimer in the
	13	* documentation and/or other materials provided with the distribution.
	14	*
	15	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
	16	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	17	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	18	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	19	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	20	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	21	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	22	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	23	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	24	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	25	*/
	26
	27	#include "includes.h"
	28
	29	#ifdef GSSAPI
	30	#ifdef KRB5
	31
	32	#include "auth.h"
88928908	33	#include "xmalloc.h"
	34	#include "log.h"
	35	#include "servconf.h"
	36
	37	#include "ssh-gss.h"
	38
	39	extern ServerOptions options;
	40
	41	#ifdef HEIMDAL
416fd2a8	42	# include <krb5.h>
88928908	43	#else
416fd2a8	44	# ifdef HAVE_GSSAPI_KRB5
	45	# include <gssapi_krb5.h>
	46	# elif HAVE_GSSAPI_GSSAPI_KRB5
	47	# include <gssapi/gssapi_krb5.h>
	48	# endif
88928908	49	#endif
88928908	50
88928908	51	static krb5_context krb_context = NULL;
2a304a95	52	static int ssh_gssapi_krb5_init();
	53	static int ssh_gssapi_krb5_userok(ssh_gssapi_client client, char name);
	54	static int ssh_gssapi_krb5_localname(ssh_gssapi_client client, char *user);
	55	static void ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client);
	56
	57	ssh_gssapi_mech gssapi_kerberos_mech = {
	58	"toWM5Slw5Ew8Mqkay+al2g==",
	59	"Kerberos",
	60	{9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
	61	NULL,
	62	&ssh_gssapi_krb5_userok,
	63	&ssh_gssapi_krb5_localname,
	64	&ssh_gssapi_krb5_storecreds
	65	};
	66
	67	ssh_gssapi_mech gssapi_kerberos_mech_old = {
	68	"Se3H81ismmOC3OE+FwYCiQ==",
	69	"Kerberos",
	70	{9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
	71	&ssh_gssapi_krb5_init,
	72	&ssh_gssapi_krb5_userok,
	73	&ssh_gssapi_krb5_localname,
	74	&ssh_gssapi_krb5_storecreds
	75	};
88928908	76
70791e56	77	/* Initialise the krb5 library, for the stuff that GSSAPI won't do */
88928908	78
416fd2a8	79	static int
1b56ff3d	80	ssh_gssapi_krb5_init(void)
70791e56	81	{
88928908	82	krb5_error_code problem;
70791e56	83
70791e56	84	if (krb_context != NULL)
88928908	85	return 1;
70791e56	86
88928908	87	problem = krb5_init_context(&krb_context);
88928908	88	if (problem) {
70791e56	89	logit("Cannot initialize krb5 context");
88928908	90	return 0;
88928908	91	}
2a304a95	92	#ifdef KRB5_INIT_ETS
88928908	93	krb5_init_ets(krb_context);
2a304a95	94	#endif
88928908	95
70791e56	96	return 1;
70791e56	97	}
88928908	98
70791e56	99	/* Check if this user is OK to login. This only works with krb5 - other
88928908	100	* GSSAPI mechanisms will need their own.
	101	* Returns true if the user is OK to log in, otherwise returns 0
	102	*/
	103
	104	static int
70791e56	105	ssh_gssapi_krb5_userok(ssh_gssapi_client client, char name)
70791e56	106	{
88928908	107	krb5_principal princ;
	108	int retval;
	109
	110	if (ssh_gssapi_krb5_init() == 0)
	111	return 0;
70791e56	112
	113	if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
	114	&princ))) {
	115	logit("krb5_parse_name(): %.100s",
	116	krb5_get_err_text(krb_context, retval));
88928908	117	return 0;
	118	}
	119	if (krb5_kuserok(krb_context, princ, name)) {
	120	retval = 1;
70791e56	121	logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
	122	name, (char *)client->displayname.value);
	123	} else
88928908	124	retval = 0;
70791e56	125
88928908	126	krb5_free_principal(krb_context, princ);
	127	return retval;
	128	}
	129
70791e56	130
88928908	131	/* Retrieve the local username associated with a set of Kerberos
	132	* credentials. Hopefully we can use this for the 'empty' username
	133	* logins discussed in the draft */
	134	static int
	135	ssh_gssapi_krb5_localname(ssh_gssapi_client client, char *user) {
	136	krb5_principal princ;
	137	int retval;
	138
	139	if (ssh_gssapi_krb5_init() == 0)
	140	return 0;
	141
70791e56	142	if ((retval=krb5_parse_name(krb_context, client->displayname.value,
88928908	143	&princ))) {
70791e56	144	logit("krb5_parse_name(): %.100s",
88928908	145	krb5_get_err_text(krb_context,retval));
	146	return 0;
	147	}
	148
	149	/* We've got to return a malloc'd string */
	150	user = (char )xmalloc(256);
	151	if (krb5_aname_to_localname(krb_context, princ, 256, *user)) {
	152	xfree(*user);
	153	*user = NULL;
	154	return(0);
	155	}
	156
	157	return(1);
	158	}
	159
70791e56	160	/* This writes out any forwarded credentials from the structure populated
70791e56	161	* during userauth. Called after we have setuid to the user */
88928908	162
88928908	163	static void
70791e56	164	ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
70791e56	165	{
88928908	166	krb5_ccache ccache;
	167	krb5_error_code problem;
	168	krb5_principal princ;
70791e56	169	OM_uint32 maj_status, min_status;
88928908	170	gss_cred_id_t krb5_cred_handle;
416fd2a8	171	int len;
70791e56	172
	173	if (client->creds == NULL) {
	174	debug("No credentials stored");
88928908	175	return;
88928908	176	}
70791e56	177
88928908	178	if (ssh_gssapi_krb5_init() == 0)
	179	return;
	180
70791e56	181	#ifdef HEIMDAL
	182	if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
	183	logit("krb5_cc_gen_new(): %.100s",
	184	krb5_get_err_text(krb_context, problem));
88928908	185	return;
88928908	186	}
70791e56	187	#else
	188	{
	189	int tmpfd;
	190	char ccname[40];
1b56ff3d	191	mode_t old_umask;
416fd2a8	192
416fd2a8	193	snprintf(ccname, sizeof(ccname),
70791e56	194	"FILE:/tmp/krb5cc_%d_XXXXXX", geteuid());
416fd2a8	195
1b56ff3d	196	old_umask = umask(0177);
	197	tmpfd = mkstemp(ccname + strlen("FILE:"));
	198	umask(old_umask);
	199	if (tmpfd == -1) {
70791e56	200	logit("mkstemp(): %.100s", strerror(errno));
	201	problem = errno;
	202	return;
	203	}
	204	if (fchmod(tmpfd, S_IRUSR \| S_IWUSR) == -1) {
	205	logit("fchmod(): %.100s", strerror(errno));
	206	close(tmpfd);
	207	problem = errno;
	208	return;
	209	}
	210	close(tmpfd);
	211	if ((problem = krb5_cc_resolve(krb_context, ccname, &ccache))) {
	212	logit("krb5_cc_resolve(): %.100s",
	213	krb5_get_err_text(krb_context, problem));
	214	return;
	215	}
	216	}
	217	#endif /* #ifdef HEIMDAL */
	218
416fd2a8	219	if ((problem = krb5_parse_name(krb_context,
70791e56	220	client->exportedname.value, &princ))) {
	221	logit("krb5_parse_name(): %.100s",
	222	krb5_get_err_text(krb_context, problem));
	223	krb5_cc_destroy(krb_context, ccache);
	224	return;
	225	}
	226
88928908	227	if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
70791e56	228	logit("krb5_cc_initialize(): %.100s",
	229	krb5_get_err_text(krb_context, problem));
	230	krb5_free_principal(krb_context, princ);
	231	krb5_cc_destroy(krb_context, ccache);
88928908	232	return;
88928908	233	}
70791e56	234
70791e56	235	krb5_free_principal(krb_context, princ);
88928908	236
	237	#ifdef MECHGLUE
	238	krb5_cred_handle =
	239	__gss_get_mechanism_cred(client->creds,
	240	&(gssapi_kerberos_mech.oid));
	241	#else
	242	krb5_cred_handle = client->creds;
	243	#endif
	244
	245	if ((maj_status = gss_krb5_copy_ccache(&min_status,
70791e56	246	krb5_cred_handle, ccache))) {
	247	logit("gss_krb5_copy_ccache() failed");
	248	krb5_cc_destroy(krb_context, ccache);
88928908	249	return;
88928908	250	}
70791e56	251
	252	client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
	253	client->store.envvar = "KRB5CCNAME";
416fd2a8	254	len = strlen(client->store.filename) + 6;
	255	client->store.envval = xmalloc(len);
	256	snprintf(client->store.envval, len, "FILE:%s", client->store.filename);
88928908	257
88928908	258	#ifdef USE_PAM
70791e56	259	if (options.use_pam)
416fd2a8	260	do_pam_putenv(client->store.envvar, client->store.envval);
88928908	261	#endif
88928908	262
70791e56	263	krb5_cc_close(krb_context, ccache);
88928908	264
	265	return;
	266	}
	267
	268	#endif /* KRB5 */
	269
	270	#endif /* GSSAPI */