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

/*	$OpenBSD: gss-serv-krb5.c,v 1.1 2003/08/22 10:56:09 markus 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
#include <gssapi_krb5.h>
#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;


	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";
	client->store.envval = xstrdup(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
7cac2b65	1	/* $OpenBSD: gss-serv-krb5.c,v 1.1 2003/08/22 10:56:09 markus 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
	42	#include <krb5.h>
	43	#else
	44	#include <gssapi_krb5.h>
f4b9ce42	45	#endif
	46
	47	static krb5_context krb_context = NULL;
	48
7cac2b65	49	/* Initialise the krb5 library, for the stuff that GSSAPI won't do */
f4b9ce42	50
f4b9ce42	51	static int
7cac2b65	52	ssh_gssapi_krb5_init()
7cac2b65	53	{
f4b9ce42	54	krb5_error_code problem;
7cac2b65	55
7cac2b65	56	if (krb_context != NULL)
f4b9ce42	57	return 1;
7cac2b65	58
f4b9ce42	59	problem = krb5_init_context(&krb_context);
f4b9ce42	60	if (problem) {
7cac2b65	61	logit("Cannot initialize krb5 context");
f4b9ce42	62	return 0;
	63	}
	64	krb5_init_ets(krb_context);
	65
7cac2b65	66	return 1;
7cac2b65	67	}
f4b9ce42	68
7cac2b65	69	/* Check if this user is OK to login. This only works with krb5 - other
f4b9ce42	70	* GSSAPI mechanisms will need their own.
	71	* Returns true if the user is OK to log in, otherwise returns 0
	72	*/
	73
	74	static int
7cac2b65	75	ssh_gssapi_krb5_userok(ssh_gssapi_client client, char name)
7cac2b65	76	{
f4b9ce42	77	krb5_principal princ;
	78	int retval;
	79
	80	if (ssh_gssapi_krb5_init() == 0)
	81	return 0;
7cac2b65	82
	83	if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
	84	&princ))) {
	85	logit("krb5_parse_name(): %.100s",
	86	krb5_get_err_text(krb_context, retval));
f4b9ce42	87	return 0;
	88	}
	89	if (krb5_kuserok(krb_context, princ, name)) {
	90	retval = 1;
7cac2b65	91	logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
	92	name, (char *)client->displayname.value);
	93	} else
f4b9ce42	94	retval = 0;
7cac2b65	95
f4b9ce42	96	krb5_free_principal(krb_context, princ);
	97	return retval;
	98	}
	99
7cac2b65	100
f4b9ce42	101	/* Retrieve the local username associated with a set of Kerberos
	102	* credentials. Hopefully we can use this for the 'empty' username
	103	* logins discussed in the draft */
	104	static int
	105	ssh_gssapi_krb5_localname(ssh_gssapi_client client, char *user) {
	106	krb5_principal princ;
	107	int retval;
	108
	109	if (ssh_gssapi_krb5_init() == 0)
	110	return 0;
	111
7cac2b65	112	if ((retval=krb5_parse_name(krb_context, client->displayname.value,
f4b9ce42	113	&princ))) {
7cac2b65	114	logit("krb5_parse_name(): %.100s",
f4b9ce42	115	krb5_get_err_text(krb_context,retval));
	116	return 0;
	117	}
	118
	119	/* We've got to return a malloc'd string */
	120	user = (char )xmalloc(256);
	121	if (krb5_aname_to_localname(krb_context, princ, 256, *user)) {
	122	xfree(*user);
	123	*user = NULL;
	124	return(0);
	125	}
	126
	127	return(1);
	128	}
	129
7cac2b65	130	/* This writes out any forwarded credentials from the structure populated
7cac2b65	131	* during userauth. Called after we have setuid to the user */
f4b9ce42	132
f4b9ce42	133	static void
7cac2b65	134	ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
7cac2b65	135	{
f4b9ce42	136	krb5_ccache ccache;
	137	krb5_error_code problem;
	138	krb5_principal princ;
7cac2b65	139	OM_uint32 maj_status, min_status;
81d08144	140	gss_cred_id_t krb5_cred_handle;
f4b9ce42	141
7cac2b65	142
	143	if (client->creds == NULL) {
	144	debug("No credentials stored");
f4b9ce42	145	return;
f4b9ce42	146	}
7cac2b65	147
f4b9ce42	148	if (ssh_gssapi_krb5_init() == 0)
	149	return;
	150
7cac2b65	151	#ifdef HEIMDAL
	152	if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
	153	logit("krb5_cc_gen_new(): %.100s",
	154	krb5_get_err_text(krb_context, problem));
f4b9ce42	155	return;
f4b9ce42	156	}
7cac2b65	157	#else
	158	{
	159	int tmpfd;
	160	char ccname[40];
	161
	162	snprintf(ccname, sizeof(ccname),
	163	"FILE:/tmp/krb5cc_%d_XXXXXX", geteuid());
	164
	165	if ((tmpfd = mkstemp(ccname + strlen("FILE:"))) == -1) {
	166	logit("mkstemp(): %.100s", strerror(errno));
	167	problem = errno;
	168	return;
	169	}
	170	if (fchmod(tmpfd, S_IRUSR \| S_IWUSR) == -1) {
	171	logit("fchmod(): %.100s", strerror(errno));
	172	close(tmpfd);
	173	problem = errno;
	174	return;
	175	}
	176	close(tmpfd);
	177	if ((problem = krb5_cc_resolve(krb_context, ccname, &ccache))) {
	178	logit("krb5_cc_resolve(): %.100s",
	179	krb5_get_err_text(krb_context, problem));
	180	return;
	181	}
	182	}
	183	#endif /* #ifdef HEIMDAL */
	184
	185	if ((problem = krb5_parse_name(krb_context,
	186	client->exportedname.value, &princ))) {
	187	logit("krb5_parse_name(): %.100s",
	188	krb5_get_err_text(krb_context, problem));
	189	krb5_cc_destroy(krb_context, ccache);
	190	return;
	191	}
	192
f4b9ce42	193	if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
7cac2b65	194	logit("krb5_cc_initialize(): %.100s",
	195	krb5_get_err_text(krb_context, problem));
	196	krb5_free_principal(krb_context, princ);
	197	krb5_cc_destroy(krb_context, ccache);
f4b9ce42	198	return;
f4b9ce42	199	}
7cac2b65	200
7cac2b65	201	krb5_free_principal(krb_context, princ);
f4b9ce42	202
81d08144	203	#ifdef MECHGLUE
	204	krb5_cred_handle =
	205	__gss_get_mechanism_cred(client->creds,
	206	&(gssapi_kerberos_mech.oid));
	207	#else
2af4b8d5	208	krb5_cred_handle = client->creds;
81d08144	209	#endif
81d08144	210
f4b9ce42	211	if ((maj_status = gss_krb5_copy_ccache(&min_status,
7cac2b65	212	krb5_cred_handle, ccache))) {
	213	logit("gss_krb5_copy_ccache() failed");
	214	krb5_cc_destroy(krb_context, ccache);
f4b9ce42	215	return;
f4b9ce42	216	}
7cac2b65	217
	218	client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
	219	client->store.envvar = "KRB5CCNAME";
	220	client->store.envval = xstrdup(client->store.filename);
f4b9ce42	221
f4b9ce42	222	#ifdef USE_PAM
7cac2b65	223	if (options.use_pam)
7cac2b65	224	do_pam_putenv(client->store.envvar,client->store.envval);
f4b9ce42	225	#endif
f4b9ce42	226
7cac2b65	227	krb5_cc_close(krb_context, ccache);
f4b9ce42	228
	229	return;
	230	}
	231
7cac2b65	232	ssh_gssapi_mech gssapi_kerberos_mech = {
	233	"toWM5Slw5Ew8Mqkay+al2g==",
	234	"Kerberos",
	235	{9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
	236	NULL,
	237	&ssh_gssapi_krb5_userok,
	238	&ssh_gssapi_krb5_localname,
	239	&ssh_gssapi_krb5_storecreds
	240	};
	241
	242	ssh_gssapi_mech gssapi_kerberos_mech_old = {
	243	"Se3H81ismmOC3OE+FwYCiQ==",
	244	"Kerberos",
	245	{9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
	246	&ssh_gssapi_krb5_init,
	247	&ssh_gssapi_krb5_userok,
	248	&ssh_gssapi_krb5_localname,
	249	&ssh_gssapi_krb5_storecreds
	250	};
	251
f4b9ce42	252	#endif /* KRB5 */
	253
	254	#endif /* GSSAPI */