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

/*	$OpenBSD: gss-serv-krb5.c,v 1.2 2003/11/21 11:57:03 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;

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

static int
ssh_gssapi_krb5_init()
{
	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;
	}
	krb5_init_ets(krb_context);

	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];

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

		if ((tmpfd = mkstemp(ccname + strlen("FILE:"))) == -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;
}

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
};

#endif /* KRB5 */

#endif /* GSSAPI */
Commit	Line	Data
416fd2a8	1	/* $OpenBSD: gss-serv-krb5.c,v 1.2 2003/11/21 11:57:03 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;
88928908	52
70791e56	53	/* Initialise the krb5 library, for the stuff that GSSAPI won't do */
88928908	54
416fd2a8	55	static int
70791e56	56	ssh_gssapi_krb5_init()
70791e56	57	{
88928908	58	krb5_error_code problem;
70791e56	59
70791e56	60	if (krb_context != NULL)
88928908	61	return 1;
70791e56	62
88928908	63	problem = krb5_init_context(&krb_context);
88928908	64	if (problem) {
70791e56	65	logit("Cannot initialize krb5 context");
88928908	66	return 0;
	67	}
	68	krb5_init_ets(krb_context);
	69
70791e56	70	return 1;
70791e56	71	}
88928908	72
70791e56	73	/* Check if this user is OK to login. This only works with krb5 - other
88928908	74	* GSSAPI mechanisms will need their own.
	75	* Returns true if the user is OK to log in, otherwise returns 0
	76	*/
	77
	78	static int
70791e56	79	ssh_gssapi_krb5_userok(ssh_gssapi_client client, char name)
70791e56	80	{
88928908	81	krb5_principal princ;
	82	int retval;
	83
	84	if (ssh_gssapi_krb5_init() == 0)
	85	return 0;
70791e56	86
	87	if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
	88	&princ))) {
	89	logit("krb5_parse_name(): %.100s",
	90	krb5_get_err_text(krb_context, retval));
88928908	91	return 0;
	92	}
	93	if (krb5_kuserok(krb_context, princ, name)) {
	94	retval = 1;
70791e56	95	logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
	96	name, (char *)client->displayname.value);
	97	} else
88928908	98	retval = 0;
70791e56	99
88928908	100	krb5_free_principal(krb_context, princ);
	101	return retval;
	102	}
	103
70791e56	104
88928908	105	/* Retrieve the local username associated with a set of Kerberos
	106	* credentials. Hopefully we can use this for the 'empty' username
	107	* logins discussed in the draft */
	108	static int
	109	ssh_gssapi_krb5_localname(ssh_gssapi_client client, char *user) {
	110	krb5_principal princ;
	111	int retval;
	112
	113	if (ssh_gssapi_krb5_init() == 0)
	114	return 0;
	115
70791e56	116	if ((retval=krb5_parse_name(krb_context, client->displayname.value,
88928908	117	&princ))) {
70791e56	118	logit("krb5_parse_name(): %.100s",
88928908	119	krb5_get_err_text(krb_context,retval));
	120	return 0;
	121	}
	122
	123	/* We've got to return a malloc'd string */
	124	user = (char )xmalloc(256);
	125	if (krb5_aname_to_localname(krb_context, princ, 256, *user)) {
	126	xfree(*user);
	127	*user = NULL;
	128	return(0);
	129	}
	130
	131	return(1);
	132	}
	133
70791e56	134	/* This writes out any forwarded credentials from the structure populated
70791e56	135	* during userauth. Called after we have setuid to the user */
88928908	136
88928908	137	static void
70791e56	138	ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
70791e56	139	{
88928908	140	krb5_ccache ccache;
	141	krb5_error_code problem;
	142	krb5_principal princ;
70791e56	143	OM_uint32 maj_status, min_status;
88928908	144	gss_cred_id_t krb5_cred_handle;
416fd2a8	145	int len;
70791e56	146
	147	if (client->creds == NULL) {
	148	debug("No credentials stored");
88928908	149	return;
88928908	150	}
70791e56	151
88928908	152	if (ssh_gssapi_krb5_init() == 0)
	153	return;
	154
70791e56	155	#ifdef HEIMDAL
	156	if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
	157	logit("krb5_cc_gen_new(): %.100s",
	158	krb5_get_err_text(krb_context, problem));
88928908	159	return;
88928908	160	}
70791e56	161	#else
	162	{
	163	int tmpfd;
	164	char ccname[40];
416fd2a8	165
416fd2a8	166	snprintf(ccname, sizeof(ccname),
70791e56	167	"FILE:/tmp/krb5cc_%d_XXXXXX", geteuid());
416fd2a8	168
70791e56	169	if ((tmpfd = mkstemp(ccname + strlen("FILE:"))) == -1) {
	170	logit("mkstemp(): %.100s", strerror(errno));
	171	problem = errno;
	172	return;
	173	}
	174	if (fchmod(tmpfd, S_IRUSR \| S_IWUSR) == -1) {
	175	logit("fchmod(): %.100s", strerror(errno));
	176	close(tmpfd);
	177	problem = errno;
	178	return;
	179	}
	180	close(tmpfd);
	181	if ((problem = krb5_cc_resolve(krb_context, ccname, &ccache))) {
	182	logit("krb5_cc_resolve(): %.100s",
	183	krb5_get_err_text(krb_context, problem));
	184	return;
	185	}
	186	}
	187	#endif /* #ifdef HEIMDAL */
	188
416fd2a8	189	if ((problem = krb5_parse_name(krb_context,
70791e56	190	client->exportedname.value, &princ))) {
	191	logit("krb5_parse_name(): %.100s",
	192	krb5_get_err_text(krb_context, problem));
	193	krb5_cc_destroy(krb_context, ccache);
	194	return;
	195	}
	196
88928908	197	if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
70791e56	198	logit("krb5_cc_initialize(): %.100s",
	199	krb5_get_err_text(krb_context, problem));
	200	krb5_free_principal(krb_context, princ);
	201	krb5_cc_destroy(krb_context, ccache);
88928908	202	return;
88928908	203	}
70791e56	204
70791e56	205	krb5_free_principal(krb_context, princ);
88928908	206
	207	#ifdef MECHGLUE
	208	krb5_cred_handle =
	209	__gss_get_mechanism_cred(client->creds,
	210	&(gssapi_kerberos_mech.oid));
	211	#else
	212	krb5_cred_handle = client->creds;
	213	#endif
	214
	215	if ((maj_status = gss_krb5_copy_ccache(&min_status,
70791e56	216	krb5_cred_handle, ccache))) {
	217	logit("gss_krb5_copy_ccache() failed");
	218	krb5_cc_destroy(krb_context, ccache);
88928908	219	return;
88928908	220	}
70791e56	221
	222	client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
	223	client->store.envvar = "KRB5CCNAME";
416fd2a8	224	len = strlen(client->store.filename) + 6;
	225	client->store.envval = xmalloc(len);
	226	snprintf(client->store.envval, len, "FILE:%s", client->store.filename);
88928908	227
88928908	228	#ifdef USE_PAM
70791e56	229	if (options.use_pam)
416fd2a8	230	do_pam_putenv(client->store.envvar, client->store.envval);
88928908	231	#endif
88928908	232
70791e56	233	krb5_cc_close(krb_context, ccache);
88928908	234
	235	return;
	236	}
	237
70791e56	238	ssh_gssapi_mech gssapi_kerberos_mech = {
	239	"toWM5Slw5Ew8Mqkay+al2g==",
	240	"Kerberos",
	241	{9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
	242	NULL,
	243	&ssh_gssapi_krb5_userok,
	244	&ssh_gssapi_krb5_localname,
	245	&ssh_gssapi_krb5_storecreds
	246	};
	247
	248	ssh_gssapi_mech gssapi_kerberos_mech_old = {
	249	"Se3H81ismmOC3OE+FwYCiQ==",
	250	"Kerberos",
	251	{9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
	252	&ssh_gssapi_krb5_init,
	253	&ssh_gssapi_krb5_userok,
	254	&ssh_gssapi_krb5_localname,
	255	&ssh_gssapi_krb5_storecreds
	256	};
	257
88928908	258	#endif /* KRB5 */
	259
	260	#endif /* GSSAPI */