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

/* $OpenBSD: gss-serv-krb5.c,v 1.7 2006/08/03 03:34:42 deraadt Exp $ */

/*
 * Copyright (c) 2001-2007 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 <sys/types.h>

#include <stdarg.h>
#include <string.h>

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

#include "buffer.h"
#include "ssh-gss.h"

extern ServerOptions options;

#ifdef HEIMDAL
# include <krb5.h>
#elif !defined(MECHGLUE)
# ifdef HAVE_GSSAPI_KRB5_H
#  include <gssapi_krb5.h>
# elif HAVE_GSSAPI_GSSAPI_KRB5_H
#  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_krb5_updatecreds
};

/* 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;
	}

	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;
	const char *new_ccname;

	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
	if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) {
		logit("ssh_krb5_cc_gen(): %.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;
	}

	new_ccname = krb5_cc_get_name(krb_context, ccache);

	client->store.envvar = "KRB5CCNAME";
#ifdef USE_CCAPI
	xasprintf(&client->store.envval, "API:%s", new_ccname);
	client->store.filename = NULL;
#else
	xasprintf(&client->store.envval, "FILE:%s", new_ccname);
	client->store.filename = xstrdup(new_ccname);
#endif

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

	krb5_cc_close(krb_context, ccache);

	return;
}

int
ssh_gssapi_krb5_updatecreds(ssh_gssapi_ccache *store, 
    ssh_gssapi_client *client)
{
	krb5_ccache ccache = NULL;
	krb5_principal principal = NULL;
	char *name = NULL;
	krb5_error_code problem;
	OM_uint32 maj_status, min_status;

   	if ((problem = krb5_cc_resolve(krb_context, store->envval, &ccache))) {
                logit("krb5_cc_resolve(): %.100s",
                    krb5_get_err_text(krb_context, problem));
                return 0;
       	}
	
	/* Find out who the principal in this cache is */
	if ((problem = krb5_cc_get_principal(krb_context, ccache, 
	    &principal))) {
		logit("krb5_cc_get_principal(): %.100s",
		    krb5_get_err_text(krb_context, problem));
		krb5_cc_close(krb_context, ccache);
		return 0;
	}

	if ((problem = krb5_unparse_name(krb_context, principal, &name))) {
		logit("krb5_unparse_name(): %.100s",
		    krb5_get_err_text(krb_context, problem));
		krb5_free_principal(krb_context, principal);
		krb5_cc_close(krb_context, ccache);
		return 0;
	}


	if (strcmp(name,client->exportedname.value)!=0) {
		debug("Name in local credentials cache differs. Not storing");
		krb5_free_principal(krb_context, principal);
		krb5_cc_close(krb_context, ccache);
		krb5_free_unparsed_name(krb_context, name);
		return 0;
	}
	krb5_free_unparsed_name(krb_context, name);

	/* Name matches, so lets get on with it! */

	if ((problem = krb5_cc_initialize(krb_context, ccache, principal))) {
		logit("krb5_cc_initialize(): %.100s",
		    krb5_get_err_text(krb_context, problem));
		krb5_free_principal(krb_context, principal);
		krb5_cc_close(krb_context, ccache);
		return 0;
	}

	krb5_free_principal(krb_context, principal);

	if ((maj_status = gss_krb5_copy_ccache(&min_status, client->creds,
	    ccache))) {
		logit("gss_krb5_copy_ccache() failed. Sorry!");
		krb5_cc_close(krb_context, ccache);
		return 0;
	}

	return 1;
}

#endif /* KRB5 */

#endif /* GSSAPI */
Commit	Line	Data
30460aeb	1	/* $OpenBSD: gss-serv-krb5.c,v 1.7 2006/08/03 03:34:42 deraadt Exp $ */
7cac2b65	2
f4b9ce42	3	/*
f97edba6	4	* Copyright (c) 2001-2007 Simon Wilkinson. All rights reserved.
f4b9ce42	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
30460aeb	32	#include <sys/types.h>
	33
	34	#include <stdarg.h>
	35	#include <string.h>
	36
f4b9ce42	37	#include "xmalloc.h"
30460aeb	38	#include "key.h"
	39	#include "hostfile.h"
	40	#include "auth.h"
f4b9ce42	41	#include "log.h"
	42	#include "servconf.h"
	43
30460aeb	44	#include "buffer.h"
f4b9ce42	45	#include "ssh-gss.h"
	46
	47	extern ServerOptions options;
	48
	49	#ifdef HEIMDAL
540d72c3	50	# include <krb5.h>
48a25c13	51	#elif !defined(MECHGLUE)
fe4ad273	52	# ifdef HAVE_GSSAPI_KRB5_H
540d72c3	53	# include <gssapi_krb5.h>
fe4ad273	54	# elif HAVE_GSSAPI_GSSAPI_KRB5_H
540d72c3	55	# include <gssapi/gssapi_krb5.h>
540d72c3	56	# endif
f4b9ce42	57	#endif
	58
	59	static krb5_context krb_context = NULL;
83059c7b	60	static int ssh_gssapi_krb5_init();
	61	static int ssh_gssapi_krb5_userok(ssh_gssapi_client client, char name);
	62	static int ssh_gssapi_krb5_localname(ssh_gssapi_client client, char *user);
	63	static void ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client);
	64
	65	ssh_gssapi_mech gssapi_kerberos_mech = {
	66	"toWM5Slw5Ew8Mqkay+al2g==",
	67	"Kerberos",
	68	{9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
	69	NULL,
	70	&ssh_gssapi_krb5_userok,
	71	&ssh_gssapi_krb5_localname,
c7931c9a	72	&ssh_gssapi_krb5_storecreds,
c7931c9a	73	&ssh_gssapi_krb5_updatecreds
83059c7b	74	};
83059c7b	75
7cac2b65	76	/* Initialise the krb5 library, for the stuff that GSSAPI won't do */
f4b9ce42	77
540d72c3	78	static int
7e82606e	79	ssh_gssapi_krb5_init(void)
7cac2b65	80	{
f4b9ce42	81	krb5_error_code problem;
7cac2b65	82
7cac2b65	83	if (krb_context != NULL)
f4b9ce42	84	return 1;
7cac2b65	85
f4b9ce42	86	problem = krb5_init_context(&krb_context);
f4b9ce42	87	if (problem) {
7cac2b65	88	logit("Cannot initialize krb5 context");
f4b9ce42	89	return 0;
f4b9ce42	90	}
f4b9ce42	91
7cac2b65	92	return 1;
7cac2b65	93	}
f4b9ce42	94
7cac2b65	95	/* Check if this user is OK to login. This only works with krb5 - other
f4b9ce42	96	* GSSAPI mechanisms will need their own.
	97	* Returns true if the user is OK to log in, otherwise returns 0
	98	*/
	99
	100	static int
7cac2b65	101	ssh_gssapi_krb5_userok(ssh_gssapi_client client, char name)
7cac2b65	102	{
f4b9ce42	103	krb5_principal princ;
	104	int retval;
	105
	106	if (ssh_gssapi_krb5_init() == 0)
	107	return 0;
7cac2b65	108
	109	if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
	110	&princ))) {
	111	logit("krb5_parse_name(): %.100s",
	112	krb5_get_err_text(krb_context, retval));
f4b9ce42	113	return 0;
	114	}
	115	if (krb5_kuserok(krb_context, princ, name)) {
	116	retval = 1;
7cac2b65	117	logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
	118	name, (char *)client->displayname.value);
	119	} else
f4b9ce42	120	retval = 0;
7cac2b65	121
f4b9ce42	122	krb5_free_principal(krb_context, princ);
	123	return retval;
	124	}
	125
7cac2b65	126
f4b9ce42	127	/* Retrieve the local username associated with a set of Kerberos
	128	* credentials. Hopefully we can use this for the 'empty' username
	129	* logins discussed in the draft */
	130	static int
	131	ssh_gssapi_krb5_localname(ssh_gssapi_client client, char *user) {
	132	krb5_principal princ;
	133	int retval;
	134
	135	if (ssh_gssapi_krb5_init() == 0)
	136	return 0;
	137
7cac2b65	138	if ((retval=krb5_parse_name(krb_context, client->displayname.value,
f4b9ce42	139	&princ))) {
7cac2b65	140	logit("krb5_parse_name(): %.100s",
f4b9ce42	141	krb5_get_err_text(krb_context,retval));
	142	return 0;
	143	}
	144
	145	/* We've got to return a malloc'd string */
	146	user = (char )xmalloc(256);
	147	if (krb5_aname_to_localname(krb_context, princ, 256, *user)) {
	148	xfree(*user);
	149	*user = NULL;
	150	return(0);
	151	}
	152
	153	return(1);
	154	}
	155
7cac2b65	156	/* This writes out any forwarded credentials from the structure populated
7cac2b65	157	* during userauth. Called after we have setuid to the user */
f4b9ce42	158
f4b9ce42	159	static void
7cac2b65	160	ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
7cac2b65	161	{
f4b9ce42	162	krb5_ccache ccache;
	163	krb5_error_code problem;
	164	krb5_principal princ;
7cac2b65	165	OM_uint32 maj_status, min_status;
81d08144	166	gss_cred_id_t krb5_cred_handle;
540d72c3	167	int len;
0b90ac93	168	const char *new_ccname;
7cac2b65	169
	170	if (client->creds == NULL) {
	171	debug("No credentials stored");
f4b9ce42	172	return;
f4b9ce42	173	}
7cac2b65	174
f4b9ce42	175	if (ssh_gssapi_krb5_init() == 0)
	176	return;
	177
7cac2b65	178	#ifdef HEIMDAL
	179	if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
	180	logit("krb5_cc_gen_new(): %.100s",
	181	krb5_get_err_text(krb_context, problem));
f4b9ce42	182	return;
f4b9ce42	183	}
7cac2b65	184	#else
2ce0bfe4	185	if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) {
	186	logit("ssh_krb5_cc_gen(): %.100s",
	187	krb5_get_err_text(krb_context, problem));
	188	return;
7cac2b65	189	}
	190	#endif /* #ifdef HEIMDAL */
	191
540d72c3	192	if ((problem = krb5_parse_name(krb_context,
7cac2b65	193	client->exportedname.value, &princ))) {
	194	logit("krb5_parse_name(): %.100s",
	195	krb5_get_err_text(krb_context, problem));
	196	krb5_cc_destroy(krb_context, ccache);
	197	return;
	198	}
	199
f4b9ce42	200	if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
7cac2b65	201	logit("krb5_cc_initialize(): %.100s",
	202	krb5_get_err_text(krb_context, problem));
	203	krb5_free_principal(krb_context, princ);
	204	krb5_cc_destroy(krb_context, ccache);
f4b9ce42	205	return;
f4b9ce42	206	}
7cac2b65	207
7cac2b65	208	krb5_free_principal(krb_context, princ);
f4b9ce42	209
81d08144	210	#ifdef MECHGLUE
	211	krb5_cred_handle =
	212	__gss_get_mechanism_cred(client->creds,
	213	&(gssapi_kerberos_mech.oid));
	214	#else
2af4b8d5	215	krb5_cred_handle = client->creds;
81d08144	216	#endif
81d08144	217
f4b9ce42	218	if ((maj_status = gss_krb5_copy_ccache(&min_status,
7cac2b65	219	krb5_cred_handle, ccache))) {
	220	logit("gss_krb5_copy_ccache() failed");
	221	krb5_cc_destroy(krb_context, ccache);
f4b9ce42	222	return;
f4b9ce42	223	}
7cac2b65	224
f713db99	225	new_ccname = krb5_cc_get_name(krb_context, ccache);
f713db99	226
7cac2b65	227	client->store.envvar = "KRB5CCNAME";
f713db99	228	#ifdef USE_CCAPI
	229	xasprintf(&client->store.envval, "API:%s", new_ccname);
	230	client->store.filename = NULL;
	231	#else
	232	xasprintf(&client->store.envval, "FILE:%s", new_ccname);
	233	client->store.filename = xstrdup(new_ccname);
	234	#endif
f4b9ce42	235
f4b9ce42	236	#ifdef USE_PAM
7cac2b65	237	if (options.use_pam)
540d72c3	238	do_pam_putenv(client->store.envvar, client->store.envval);
f4b9ce42	239	#endif
f4b9ce42	240
7cac2b65	241	krb5_cc_close(krb_context, ccache);
f4b9ce42	242
	243	return;
	244	}
	245
f97edba6	246	int
	247	ssh_gssapi_krb5_updatecreds(ssh_gssapi_ccache *store,
	248	ssh_gssapi_client *client)
	249	{
	250	krb5_ccache ccache = NULL;
	251	krb5_principal principal = NULL;
	252	char *name = NULL;
	253	krb5_error_code problem;
	254	OM_uint32 maj_status, min_status;
	255
	256	if ((problem = krb5_cc_resolve(krb_context, store->envval, &ccache))) {
	257	logit("krb5_cc_resolve(): %.100s",
	258	krb5_get_err_text(krb_context, problem));
	259	return 0;
	260	}
	261
	262	/* Find out who the principal in this cache is */
	263	if ((problem = krb5_cc_get_principal(krb_context, ccache,
	264	&principal))) {
	265	logit("krb5_cc_get_principal(): %.100s",
	266	krb5_get_err_text(krb_context, problem));
	267	krb5_cc_close(krb_context, ccache);
	268	return 0;
	269	}
	270
	271	if ((problem = krb5_unparse_name(krb_context, principal, &name))) {
	272	logit("krb5_unparse_name(): %.100s",
	273	krb5_get_err_text(krb_context, problem));
	274	krb5_free_principal(krb_context, principal);
	275	krb5_cc_close(krb_context, ccache);
	276	return 0;
	277	}
	278
	279
	280	if (strcmp(name,client->exportedname.value)!=0) {
	281	debug("Name in local credentials cache differs. Not storing");
	282	krb5_free_principal(krb_context, principal);
	283	krb5_cc_close(krb_context, ccache);
	284	krb5_free_unparsed_name(krb_context, name);
	285	return 0;
	286	}
	287	krb5_free_unparsed_name(krb_context, name);
	288
	289	/* Name matches, so lets get on with it! */
	290
	291	if ((problem = krb5_cc_initialize(krb_context, ccache, principal))) {
	292	logit("krb5_cc_initialize(): %.100s",
	293	krb5_get_err_text(krb_context, problem));
	294	krb5_free_principal(krb_context, principal);
	295	krb5_cc_close(krb_context, ccache);
	296	return 0;
	297	}
	298
	299	krb5_free_principal(krb_context, principal);
	300
	301	if ((maj_status = gss_krb5_copy_ccache(&min_status, client->creds,
	302	ccache))) {
	303	logit("gss_krb5_copy_ccache() failed. Sorry!");
	304	krb5_cc_close(krb_context, ccache);
	305	return 0;
	306	}
	307
	308	return 1;
	309	}
310
f4b9ce42	311	#endif /* KRB5 */
	312
	313	#endif /* GSSAPI */