1 /* $OpenBSD: gss-serv-krb5.c,v 1.8 2013/07/20 01:55:13 djm 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 "misc.h"
43 #include "servconf.h"
44
45 #include "buffer.h"
46 #include "ssh-gss.h"
47
48 extern ServerOptions options;
49
50 #ifdef HEIMDAL
51 # include <krb5.h>
52 #endif
53 #ifdef HAVE_GSSAPI_KRB5_H
54 # include <gssapi_krb5.h>
55 #elif HAVE_GSSAPI_GSSAPI_KRB5_H
56 # include <gssapi/gssapi_krb5.h>
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 const char *errmsg;
91
92 if (ssh_gssapi_krb5_init() == 0)
93 return 0;
94
95 if ((retval = krb5_parse_name(krb_context, client->exportedname.value,
96 &princ))) {
97 errmsg = krb5_get_error_message(krb_context, retval);
98 logit("krb5_parse_name(): %.100s", errmsg);
99 krb5_free_error_message(krb_context, errmsg);
100 return 0;
101 }
102 if (krb5_kuserok(krb_context, princ, name)) {
103 retval = 1;
104 logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
105 name, (char *)client->displayname.value);
106 } else
107 retval = 0;
108
109 krb5_free_principal(krb_context, princ);
110 return retval;
111 }
112
113
114 /* This writes out any forwarded credentials from the structure populated
115 * during userauth. Called after we have setuid to the user */
116
117 static void
ssh_gssapi_krb5_storecreds(ssh_gssapi_client * client)118 ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
119 {
120 krb5_ccache ccache;
121 krb5_error_code problem;
122 krb5_principal princ;
123 OM_uint32 maj_status, min_status;
124 int len;
125 const char *errmsg;
126
127 if (client->creds == NULL) {
128 debug("No credentials stored");
129 return;
130 }
131
132 if (ssh_gssapi_krb5_init() == 0)
133 return;
134
135 #ifdef HEIMDAL
136 # ifdef HAVE_KRB5_CC_NEW_UNIQUE
137 if ((problem = krb5_cc_new_unique(krb_context, krb5_fcc_ops.prefix,
138 NULL, &ccache)) != 0) {
139 errmsg = krb5_get_error_message(krb_context, problem);
140 logit("krb5_cc_new_unique(): %.100s", errmsg);
141 # else
142 if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
143 logit("krb5_cc_gen_new(): %.100s",
144 krb5_get_err_text(krb_context, problem));
145 # endif
146 krb5_free_error_message(krb_context, errmsg);
147 return;
148 }
149 #else
150 if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) {
151 errmsg = krb5_get_error_message(krb_context, problem);
152 logit("ssh_krb5_cc_gen(): %.100s", errmsg);
153 krb5_free_error_message(krb_context, errmsg);
154 return;
155 }
156 #endif /* #ifdef HEIMDAL */
157
158 if ((problem = krb5_parse_name(krb_context,
159 client->exportedname.value, &princ))) {
160 errmsg = krb5_get_error_message(krb_context, problem);
161 logit("krb5_parse_name(): %.100s", errmsg);
162 krb5_free_error_message(krb_context, errmsg);
163 return;
164 }
165
166 if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
167 errmsg = krb5_get_error_message(krb_context, problem);
168 logit("krb5_cc_initialize(): %.100s", errmsg);
169 krb5_free_error_message(krb_context, errmsg);
170 krb5_free_principal(krb_context, princ);
171 krb5_cc_destroy(krb_context, ccache);
172 return;
173 }
174
175 krb5_free_principal(krb_context, princ);
176
177 if ((maj_status = gss_krb5_copy_ccache(&min_status,
178 client->creds, ccache))) {
179 logit("gss_krb5_copy_ccache() failed");
180 krb5_cc_destroy(krb_context, ccache);
181 return;
182 }
183
184 client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
185 client->store.envvar = "KRB5CCNAME";
186 len = strlen(client->store.filename) + 6;
187 client->store.envval = xmalloc(len);
188 snprintf(client->store.envval, len, "FILE:%s", client->store.filename);
189
190 #ifdef USE_PAM
191 if (options.use_pam)
192 do_pam_putenv(client->store.envvar, client->store.envval);
193 #endif
194
195 krb5_cc_close(krb_context, ccache);
196
197 return;
198 }
199
200 ssh_gssapi_mech gssapi_kerberos_mech = {
201 "toWM5Slw5Ew8Mqkay+al2g==",
202 "Kerberos",
203 {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
204 NULL,
205 &ssh_gssapi_krb5_userok,
206 NULL,
207 &ssh_gssapi_krb5_storecreds
208 };
209
210 #endif /* KRB5 */
211
212 #endif /* GSSAPI */
213