1/* $OpenBSD: gss-serv-krb5.c,v 1.7 2006/08/03 03:34:42 deraadt Exp $ */
2
3/*
4 * Copyright (c) 2001-2007 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 <sys/types.h>
33
34#include <stdarg.h>
35#include <string.h>
36
37#include "xmalloc.h"
38#include "key.h"
39#include "hostfile.h"
40#include "auth.h"
41#include "log.h"
42#include "servconf.h"
43
44#include "buffer.h"
45#include "ssh-gss.h"
46
47extern ServerOptions options;
48
49#ifdef HEIMDAL
50# include <krb5.h>
51#else
52# ifdef HAVE_GSSAPI_KRB5_H
53#  include <gssapi_krb5.h>
54# elif HAVE_GSSAPI_GSSAPI_KRB5_H
55#  include <gssapi/gssapi_krb5.h>
56# endif
57#endif
58
59#ifdef __APPLE_CROSS_REALM__
60#include <membership.h>
61#endif
62
63static krb5_context krb_context = NULL;
64
65/* Initialise the krb5 library, for the stuff that GSSAPI won't do */
66
67static int
68ssh_gssapi_krb5_init(void)
69{
70	krb5_error_code problem;
71
72	if (krb_context != NULL)
73		return 1;
74
75	problem = krb5_init_context(&krb_context);
76	if (problem) {
77		logit("Cannot initialize krb5 context");
78		return 0;
79	}
80
81	return 1;
82}
83
84#ifdef __APPLE_CROSS_REALM__
85/* Check if the principal matches any of the user's OD entries for RecordName */
86krb5_boolean
87od_kuserok(krb5_context context, krb5_principal principal, const char *luser)
88{
89	char *kprinc = NULL;
90	int ret = 0, retval = FALSE;
91	uuid_t krb_uuid, un_uuid;
92
93	ret = krb5_unparse_name(context, principal, &kprinc);
94	if (!ret) {
95		logit("od_kuserok - krb5_unparse_name failed: %d", ret);
96		goto error;
97	}
98
99	ret = mbr_identifier_to_uuid(ID_TYPE_USERNAME, luser, strlen(luser), un_uuid);
100	if (!ret) {
101		logit("od_kuserok - mbr_identifier_to_uuid: %d", ret);
102		goto error;
103	}
104
105	ret = mbr_identifier_to_uuid(ID_TYPE_KERBEROS, kprinc, strlen(kprinc), krb_uuid);
106	if (!ret) {
107		goto error;
108	}
109
110	ret = uuid_compare(krb_uuid, un_uuid);
111	if (0 == ret)  {
112		retval = TRUE;
113	}
114
115error:
116	if (kprinc)
117		free(kprinc);
118
119	return retval;
120}
121#endif
122
123/* Check if this user is OK to login. This only works with krb5 - other
124 * GSSAPI mechanisms will need their own.
125 * Returns true if the user is OK to log in, otherwise returns 0
126 */
127
128static int
129ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name)
130{
131	krb5_principal princ;
132	int retval;
133
134	if (ssh_gssapi_krb5_init() == 0)
135		return 0;
136
137	if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
138	    &princ))) {
139		logit("krb5_parse_name(): %.100s",
140		    krb5_get_err_text(krb_context, retval));
141		return 0;
142	}
143	if (krb5_kuserok(krb_context, princ, name)) {
144		retval = 1;
145		logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
146		    name, (char *)client->displayname.value);
147#ifdef __APPLE_CROSS_REALM__
148	} else if (od_kuserok(krb_context, princ, name)) {
149		retval = 1;
150		logit("Authorized to %s, krb5 principal %s (od_kuserok)",
151			  name, (char *)client->displayname.value);
152#endif
153	} else
154		retval = 0;
155
156	krb5_free_principal(krb_context, princ);
157	return retval;
158}
159
160
161/* This writes out any forwarded credentials from the structure populated
162 * during userauth. Called after we have setuid to the user */
163
164static void
165ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
166{
167	krb5_ccache ccache;
168	krb5_error_code problem;
169	krb5_principal princ;
170	OM_uint32 maj_status, min_status;
171	int len;
172	const char *new_ccname;
173
174	if (client->creds == NULL) {
175		debug("No credentials stored");
176		return;
177	}
178
179	if (ssh_gssapi_krb5_init() == 0)
180		return;
181
182#ifdef HEIMDAL
183	if ((problem = krb5_cc_gen_new(krb_context, &krb5_acc_ops, &ccache))) {
184		logit("krb5_cc_gen_new(): %.100s",
185		    krb5_get_err_text(krb_context, problem));
186		return;
187	}
188#else
189	if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) {
190		logit("ssh_krb5_cc_gen(): %.100s",
191		    krb5_get_err_text(krb_context, problem));
192		return;
193	}
194#endif	/* #ifdef HEIMDAL */
195
196	if ((problem = krb5_parse_name(krb_context,
197	    client->exportedname.value, &princ))) {
198		logit("krb5_parse_name(): %.100s",
199		    krb5_get_err_text(krb_context, problem));
200		krb5_cc_destroy(krb_context, ccache);
201		return;
202	}
203
204	if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
205		logit("krb5_cc_initialize(): %.100s",
206		    krb5_get_err_text(krb_context, problem));
207		krb5_free_principal(krb_context, princ);
208		krb5_cc_destroy(krb_context, ccache);
209		return;
210	}
211
212	krb5_free_principal(krb_context, princ);
213
214	if ((maj_status = gss_krb5_copy_ccache(&min_status,
215	    client->creds, ccache))) {
216		logit("gss_krb5_copy_ccache() failed");
217		krb5_cc_destroy(krb_context, ccache);
218		return;
219	}
220
221	new_ccname = krb5_cc_get_name(krb_context, ccache);
222
223	client->store.envvar = "KRB5CCNAME";
224#ifdef USE_CCAPI
225	xasprintf(&client->store.envval, "API:%s", new_ccname);
226	client->store.filename = NULL;
227#else
228	xasprintf(&client->store.envval, "FILE:%s", new_ccname);
229	client->store.filename = xstrdup(new_ccname);
230#endif
231
232#ifdef USE_PAM
233	if (options.use_pam)
234		do_pam_putenv(client->store.envvar, client->store.envval);
235#endif
236
237	krb5_cc_close(krb_context, ccache);
238
239	return;
240}
241
242int
243ssh_gssapi_krb5_updatecreds(ssh_gssapi_ccache *store,
244    ssh_gssapi_client *client)
245{
246	krb5_ccache ccache = NULL;
247	krb5_principal principal = NULL;
248	char *name = NULL;
249	krb5_error_code problem;
250	OM_uint32 maj_status, min_status;
251
252   	if ((problem = krb5_cc_resolve(krb_context, store->envval, &ccache))) {
253                logit("krb5_cc_resolve(): %.100s",
254                    krb5_get_err_text(krb_context, problem));
255                return 0;
256       	}
257
258	/* Find out who the principal in this cache is */
259	if ((problem = krb5_cc_get_principal(krb_context, ccache,
260	    &principal))) {
261		logit("krb5_cc_get_principal(): %.100s",
262		    krb5_get_err_text(krb_context, problem));
263		krb5_cc_close(krb_context, ccache);
264		return 0;
265	}
266
267	if ((problem = krb5_unparse_name(krb_context, principal, &name))) {
268		logit("krb5_unparse_name(): %.100s",
269		    krb5_get_err_text(krb_context, problem));
270		krb5_free_principal(krb_context, principal);
271		krb5_cc_close(krb_context, ccache);
272		return 0;
273	}
274
275
276	if (strcmp(name,client->exportedname.value)!=0) {
277		debug("Name in local credentials cache differs. Not storing");
278		krb5_free_principal(krb_context, principal);
279		krb5_cc_close(krb_context, ccache);
280		krb5_free_unparsed_name(krb_context, name);
281		return 0;
282	}
283	krb5_free_unparsed_name(krb_context, name);
284
285	/* Name matches, so lets get on with it! */
286
287	if ((problem = krb5_cc_initialize(krb_context, ccache, principal))) {
288		logit("krb5_cc_initialize(): %.100s",
289		    krb5_get_err_text(krb_context, problem));
290		krb5_free_principal(krb_context, principal);
291		krb5_cc_close(krb_context, ccache);
292		return 0;
293	}
294
295	krb5_free_principal(krb_context, principal);
296
297	if ((maj_status = gss_krb5_copy_ccache(&min_status, client->creds,
298	    ccache))) {
299		logit("gss_krb5_copy_ccache() failed. Sorry!");
300		krb5_cc_close(krb_context, ccache);
301		return 0;
302	}
303
304	return 1;
305}
306
307ssh_gssapi_mech gssapi_kerberos_mech = {
308	"toWM5Slw5Ew8Mqkay+al2g==",
309	"Kerberos",
310	{9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
311	NULL,
312	&ssh_gssapi_krb5_userok,
313	NULL,
314	&ssh_gssapi_krb5_storecreds,
315	&ssh_gssapi_krb5_updatecreds
316};
317
318#endif /* KRB5 */
319
320#endif /* GSSAPI */
321