1 /* $OpenBSD: gss-serv-krb5.c,v 1.9 2018/07/09 21:37:55 markus 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 "sshkey.h"
39 #include "hostfile.h"
40 #include "auth.h"
41 #include "log.h"
42 #include "misc.h"
43 #include "servconf.h"
44
45 #include "ssh-gss.h"
46
47 extern ServerOptions options;
48
49 #ifdef HEIMDAL
50 # include <krb5.h>
51 #endif
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
58 static krb5_context krb_context = NULL;
59
60 /* Initialise the krb5 library, for the stuff that GSSAPI won't do */
61
62 static int
ssh_gssapi_krb5_init(void)63 ssh_gssapi_krb5_init(void)
64 {
65 krb5_error_code problem;
66
67 if (krb_context != NULL)
68 return 1;
69
70 problem = krb5_init_context(&krb_context);
71 if (problem) {
72 logit("Cannot initialize krb5 context");
73 return 0;
74 }
75
76 return 1;
77 }
78
79 /* Check if this user is OK to login. This only works with krb5 - other
80 * GSSAPI mechanisms will need their own.
81 * Returns true if the user is OK to log in, otherwise returns 0
82 */
83
84 static int
ssh_gssapi_krb5_userok(ssh_gssapi_client * client,char * name)85 ssh_gssapi_krb5_userok(ssh_gssapi_client *client, char *name)
86 {
87 krb5_principal princ;
88 int retval;
89 const char *errmsg;
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 errmsg = krb5_get_error_message(krb_context, retval);
97 logit("krb5_parse_name(): %.100s", errmsg);
98 krb5_free_error_message(krb_context, errmsg);
99 return 0;
100 }
101 if (krb5_kuserok(krb_context, princ, name)) {
102 retval = 1;
103 logit("Authorized to %s, krb5 principal %s (krb5_kuserok)",
104 name, (char *)client->displayname.value);
105 } else
106 retval = 0;
107
108 krb5_free_principal(krb_context, princ);
109 return retval;
110 }
111
112
113 /* This writes out any forwarded credentials from the structure populated
114 * during userauth. Called after we have setuid to the user */
115
116 static void
ssh_gssapi_krb5_storecreds(ssh_gssapi_client * client)117 ssh_gssapi_krb5_storecreds(ssh_gssapi_client *client)
118 {
119 krb5_ccache ccache;
120 krb5_error_code problem;
121 krb5_principal princ;
122 OM_uint32 maj_status, min_status;
123 int len;
124 const char *errmsg;
125
126 if (client->creds == NULL) {
127 debug("No credentials stored");
128 return;
129 }
130
131 if (ssh_gssapi_krb5_init() == 0)
132 return;
133
134 #ifdef HEIMDAL
135 # ifdef HAVE_KRB5_CC_NEW_UNIQUE
136 if ((problem = krb5_cc_new_unique(krb_context, krb5_fcc_ops.prefix,
137 NULL, &ccache)) != 0) {
138 errmsg = krb5_get_error_message(krb_context, problem);
139 logit("krb5_cc_new_unique(): %.100s", errmsg);
140 # else
141 if ((problem = krb5_cc_gen_new(krb_context, &krb5_fcc_ops, &ccache))) {
142 logit("krb5_cc_gen_new(): %.100s",
143 krb5_get_err_text(krb_context, problem));
144 # endif
145 krb5_free_error_message(krb_context, errmsg);
146 return;
147 }
148 #else
149 if ((problem = ssh_krb5_cc_gen(krb_context, &ccache))) {
150 errmsg = krb5_get_error_message(krb_context, problem);
151 logit("ssh_krb5_cc_gen(): %.100s", errmsg);
152 krb5_free_error_message(krb_context, errmsg);
153 return;
154 }
155 #endif /* #ifdef HEIMDAL */
156
157 if ((problem = krb5_parse_name(krb_context,
158 client->exportedname.value, &princ))) {
159 errmsg = krb5_get_error_message(krb_context, problem);
160 logit("krb5_parse_name(): %.100s", errmsg);
161 krb5_free_error_message(krb_context, errmsg);
162 return;
163 }
164
165 if ((problem = krb5_cc_initialize(krb_context, ccache, princ))) {
166 errmsg = krb5_get_error_message(krb_context, problem);
167 logit("krb5_cc_initialize(): %.100s", errmsg);
168 krb5_free_error_message(krb_context, errmsg);
169 krb5_free_principal(krb_context, princ);
170 krb5_cc_destroy(krb_context, ccache);
171 return;
172 }
173
174 krb5_free_principal(krb_context, princ);
175
176 if ((maj_status = gss_krb5_copy_ccache(&min_status,
177 client->creds, ccache))) {
178 logit("gss_krb5_copy_ccache() failed");
179 krb5_cc_destroy(krb_context, ccache);
180 return;
181 }
182
183 client->store.filename = xstrdup(krb5_cc_get_name(krb_context, ccache));
184 client->store.envvar = "KRB5CCNAME";
185 len = strlen(client->store.filename) + 6;
186 client->store.envval = xmalloc(len);
187 snprintf(client->store.envval, len, "FILE:%s", client->store.filename);
188
189 #ifdef USE_PAM
190 if (options.use_pam)
191 do_pam_putenv(client->store.envvar, client->store.envval);
192 #endif
193
194 krb5_cc_close(krb_context, ccache);
195
196 return;
197 }
198
199 ssh_gssapi_mech gssapi_kerberos_mech = {
200 "toWM5Slw5Ew8Mqkay+al2g==",
201 "Kerberos",
202 {9, "\x2A\x86\x48\x86\xF7\x12\x01\x02\x02"},
203 NULL,
204 &ssh_gssapi_krb5_userok,
205 NULL,
206 &ssh_gssapi_krb5_storecreds
207 };
208
209 #endif /* KRB5 */
210
211 #endif /* GSSAPI */
212