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
47 extern 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 static krb5_context krb_context = NULL;
60
61 /* Initialise the krb5 library, for the stuff that GSSAPI won't do */
62
63 static int
ssh_gssapi_krb5_init(void)64 ssh_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
85 static int
ssh_gssapi_krb5_userok(ssh_gssapi_client * client,char * name)86 ssh_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
115 static void
ssh_gssapi_krb5_storecreds(ssh_gssapi_client * client)116 ssh_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
187 ssh_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