gss-serv-krb5.c revision 162852 
1/* $OpenBSD: gss-serv-krb5.c,v 1.7 2006/08/03 03:34:42 deraadt Exp $ */
2
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 <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
59static krb5_context krb_context = NULL;
60
61/* Initialise the krb5 library, for the stuff that GSSAPI won't do */
62
63static int
64ssh_gssapi_krb5_init(void)
65{
66	krb5_error_code problem;
67
68	if (krb_context != NULL)
69		return 1;
70
71	problem = krb5_init_context(&krb_context);
72	if (problem) {
73		logit("Cannot initialize krb5 context");
74		return 0;
75	}
76
77	return 1;
78}
79
80/* Check if this user is OK to login. This only works with krb5 - other
81 * GSSAPI mechanisms will need their own.
82 * Returns true if the user is OK to log in, otherwise returns 0
83 */
84
85static int
86ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name)
87{
88	krb5_principal princ;
89	int retval;
90
91	if (ssh_gssapi_krb5_init() == 0)
92		return 0;
93
94	if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
95	    &princ))) {
96		logit("krb5_parse_name(): %.100s",
97		    krb5_get_err_text(krb_context, retval));
98		return 0;
99	}
100	if (krb5_kuserok(krb_context, princ, name)) {
101		retval = 1;
102		logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
103		    name, (char *)client->displayname.value);
104	} else
105		retval = 0;
106
107	krb5_free_principal(krb_context, princ);
108	return retval;
109}
110
111
112/* This writes out any forwarded credentials from the structure populated
113 * during userauth. Called after we have setuid to the user */
114
115static void
116ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
117{
118	krb5_ccache ccache;
119	krb5_error_code problem;
120	krb5_principal princ;
121	OM_uint32 maj_status, min_status;
122	int len;
123
124	if (client->creds == NULL) {
125		debug("No credentials stored");
126		return;
127	}
128
129	if (ssh_gssapi_krb5_init() == 0)
130		return;
131
132#ifdef HEIMDAL
133	if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
134		logit("krb5_cc_gen_new(): %.100s",
135		    krb5_get_err_text(krb_context, problem));
136		return;
137	}
138#else
139	if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) {
140		logit("ssh_krb5_cc_gen(): %.100s",
141		    krb5_get_err_text(krb_context, problem));
142		return;
143	}
144#endif	/* #ifdef HEIMDAL */
145
146	if ((problem = krb5_parse_name(krb_context,
147	    client->exportedname.value, &princ))) {
148		logit("krb5_parse_name(): %.100s",
149		    krb5_get_err_text(krb_context, problem));
150		krb5_cc_destroy(krb_context, ccache);
151		return;
152	}
153
154	if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
155		logit("krb5_cc_initialize(): %.100s",
156		    krb5_get_err_text(krb_context, problem));
157		krb5_free_principal(krb_context, princ);
158		krb5_cc_destroy(krb_context, ccache);
159		return;
160	}
161
162	krb5_free_principal(krb_context, princ);
163
164	if ((maj_status = gss_krb5_copy_ccache(&min_status,
165	    client->creds, ccache))) {
166		logit("gss_krb5_copy_ccache() failed");
167		krb5_cc_destroy(krb_context, ccache);
168		return;
169	}
170
171	client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
172	client->store.envvar = "KRB5CCNAME";
173	len = strlen(client->store.filename) + 6;
174	client->store.envval = xmalloc(len);
175	snprintf(client->store.envval, len, "FILE:%s", client->store.filename);
176
177#ifdef USE_PAM
178	if (options.use_pam)
179		do_pam_putenv(client->store.envvar, client->store.envval);
180#endif
181
182	krb5_cc_close(krb_context, ccache);
183
184	return;
185}
186
187ssh_gssapi_mech gssapi_kerberos_mech = {
188	"toWM5Slw5Ew8Mqkay+al2g==",
189	"Kerberos",
190	{9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
191	NULL,
192	&ssh_gssapi_krb5_userok,
193	NULL,
194	&ssh_gssapi_krb5_storecreds
195};
196
197#endif /* KRB5 */
198
199#endif /* GSSAPI */
200