[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;
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()
{
	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;
}

#endif /* KRB5 */

#endif /* GSSAPI */
Commit	Line	Data
540d72c3	1	/* $OpenBSD: gss-serv-krb5.c,v 1.2 2003/11/21 11:57:03 djm Exp $ */
7cac2b65	2
f4b9ce42	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"
f4b9ce42	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
540d72c3	42	# include <krb5.h>
f4b9ce42	43	#else
540d72c3	44	# ifdef HAVE_GSSAPI_KRB5
	45	# include <gssapi_krb5.h>
	46	# elif HAVE_GSSAPI_GSSAPI_KRB5
	47	# include <gssapi/gssapi_krb5.h>
	48	# endif
f4b9ce42	49	#endif
	50
	51	static krb5_context krb_context = NULL;
83059c7b	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	};
f4b9ce42	76
7cac2b65	77	/* Initialise the krb5 library, for the stuff that GSSAPI won't do */
f4b9ce42	78
540d72c3	79	static int
7cac2b65	80	ssh_gssapi_krb5_init()
7cac2b65	81	{
f4b9ce42	82	krb5_error_code problem;
7cac2b65	83
7cac2b65	84	if (krb_context != NULL)
f4b9ce42	85	return 1;
7cac2b65	86
f4b9ce42	87	problem = krb5_init_context(&krb_context);
f4b9ce42	88	if (problem) {
7cac2b65	89	logit("Cannot initialize krb5 context");
f4b9ce42	90	return 0;
	91	}
	92	krb5_init_ets(krb_context);
	93
7cac2b65	94	return 1;
7cac2b65	95	}
f4b9ce42	96
7cac2b65	97	/* Check if this user is OK to login. This only works with krb5 - other
f4b9ce42	98	* GSSAPI mechanisms will need their own.
	99	* Returns true if the user is OK to log in, otherwise returns 0
	100	*/
	101
	102	static int
7cac2b65	103	ssh_gssapi_krb5_userok(ssh_gssapi_client client, char name)
7cac2b65	104	{
f4b9ce42	105	krb5_principal princ;
	106	int retval;
	107
	108	if (ssh_gssapi_krb5_init() == 0)
	109	return 0;
7cac2b65	110
	111	if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
	112	&princ))) {
	113	logit("krb5_parse_name(): %.100s",
	114	krb5_get_err_text(krb_context, retval));
f4b9ce42	115	return 0;
	116	}
	117	if (krb5_kuserok(krb_context, princ, name)) {
	118	retval = 1;
7cac2b65	119	logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
	120	name, (char *)client->displayname.value);
	121	} else
f4b9ce42	122	retval = 0;
7cac2b65	123
f4b9ce42	124	krb5_free_principal(krb_context, princ);
	125	return retval;
	126	}
	127
7cac2b65	128
f4b9ce42	129	/* Retrieve the local username associated with a set of Kerberos
	130	* credentials. Hopefully we can use this for the 'empty' username
	131	* logins discussed in the draft */
	132	static int
	133	ssh_gssapi_krb5_localname(ssh_gssapi_client client, char *user) {
	134	krb5_principal princ;
	135	int retval;
	136
	137	if (ssh_gssapi_krb5_init() == 0)
	138	return 0;
	139
7cac2b65	140	if ((retval=krb5_parse_name(krb_context, client->displayname.value,
f4b9ce42	141	&princ))) {
7cac2b65	142	logit("krb5_parse_name(): %.100s",
f4b9ce42	143	krb5_get_err_text(krb_context,retval));
	144	return 0;
	145	}
	146
	147	/* We've got to return a malloc'd string */
	148	user = (char )xmalloc(256);
	149	if (krb5_aname_to_localname(krb_context, princ, 256, *user)) {
	150	xfree(*user);
	151	*user = NULL;
	152	return(0);
	153	}
	154
	155	return(1);
	156	}
	157
7cac2b65	158	/* This writes out any forwarded credentials from the structure populated
7cac2b65	159	* during userauth. Called after we have setuid to the user */
f4b9ce42	160
f4b9ce42	161	static void
7cac2b65	162	ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
7cac2b65	163	{
f4b9ce42	164	krb5_ccache ccache;
	165	krb5_error_code problem;
	166	krb5_principal princ;
7cac2b65	167	OM_uint32 maj_status, min_status;
81d08144	168	gss_cred_id_t krb5_cred_handle;
540d72c3	169	int len;
7cac2b65	170
	171	if (client->creds == NULL) {
	172	debug("No credentials stored");
f4b9ce42	173	return;
f4b9ce42	174	}
7cac2b65	175
f4b9ce42	176	if (ssh_gssapi_krb5_init() == 0)
	177	return;
	178
7cac2b65	179	#ifdef HEIMDAL
	180	if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
	181	logit("krb5_cc_gen_new(): %.100s",
	182	krb5_get_err_text(krb_context, problem));
f4b9ce42	183	return;
f4b9ce42	184	}
7cac2b65	185	#else
	186	{
	187	int tmpfd;
	188	char ccname[40];
540d72c3	189
540d72c3	190	snprintf(ccname, sizeof(ccname),
7cac2b65	191	"FILE:/tmp/krb5cc_%d_XXXXXX", geteuid());
540d72c3	192
7cac2b65	193	if ((tmpfd = mkstemp(ccname + strlen("FILE:"))) == -1) {
	194	logit("mkstemp(): %.100s", strerror(errno));
	195	problem = errno;
	196	return;
	197	}
	198	if (fchmod(tmpfd, S_IRUSR \| S_IWUSR) == -1) {
	199	logit("fchmod(): %.100s", strerror(errno));
	200	close(tmpfd);
	201	problem = errno;
	202	return;
	203	}
	204	close(tmpfd);
	205	if ((problem = krb5_cc_resolve(krb_context, ccname, &ccache))) {
	206	logit("krb5_cc_resolve(): %.100s",
	207	krb5_get_err_text(krb_context, problem));
	208	return;
	209	}
	210	}
	211	#endif /* #ifdef HEIMDAL */
	212
540d72c3	213	if ((problem = krb5_parse_name(krb_context,
7cac2b65	214	client->exportedname.value, &princ))) {
	215	logit("krb5_parse_name(): %.100s",
	216	krb5_get_err_text(krb_context, problem));
	217	krb5_cc_destroy(krb_context, ccache);
	218	return;
	219	}
	220
f4b9ce42	221	if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
7cac2b65	222	logit("krb5_cc_initialize(): %.100s",
	223	krb5_get_err_text(krb_context, problem));
	224	krb5_free_principal(krb_context, princ);
	225	krb5_cc_destroy(krb_context, ccache);
f4b9ce42	226	return;
f4b9ce42	227	}
7cac2b65	228
7cac2b65	229	krb5_free_principal(krb_context, princ);
f4b9ce42	230
81d08144	231	#ifdef MECHGLUE
	232	krb5_cred_handle =
	233	__gss_get_mechanism_cred(client->creds,
	234	&(gssapi_kerberos_mech.oid));
	235	#else
2af4b8d5	236	krb5_cred_handle = client->creds;
81d08144	237	#endif
81d08144	238
f4b9ce42	239	if ((maj_status = gss_krb5_copy_ccache(&min_status,
7cac2b65	240	krb5_cred_handle, ccache))) {
	241	logit("gss_krb5_copy_ccache() failed");
	242	krb5_cc_destroy(krb_context, ccache);
f4b9ce42	243	return;
f4b9ce42	244	}
7cac2b65	245
	246	client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
	247	client->store.envvar = "KRB5CCNAME";
540d72c3	248	len = strlen(client->store.filename) + 6;
	249	client->store.envval = xmalloc(len);
	250	snprintf(client->store.envval, len, "FILE:%s", client->store.filename);
f4b9ce42	251
f4b9ce42	252	#ifdef USE_PAM
7cac2b65	253	if (options.use_pam)
540d72c3	254	do_pam_putenv(client->store.envvar, client->store.envval);
f4b9ce42	255	#endif
f4b9ce42	256
7cac2b65	257	krb5_cc_close(krb_context, ccache);
f4b9ce42	258
	259	return;
	260	}
	261
f4b9ce42	262	#endif /* KRB5 */
	263
	264	#endif /* GSSAPI */