blob: c7651112d10a8820530decb9c2e0d7ecdf0ea6d5 [file] [log] [blame]
Darren Tucker0efd1552003-08-26 11:49:55 +10001/* $OpenBSD: auth2-gss.c,v 1.1 2003/08/22 10:56:08 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
31#include "auth.h"
32#include "ssh2.h"
33#include "xmalloc.h"
34#include "log.h"
35#include "dispatch.h"
36#include "servconf.h"
37#include "compat.h"
38#include "packet.h"
39#include "monitor_wrap.h"
40
41#include "ssh-gss.h"
42
43extern ServerOptions options;
44
45static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
46static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
47static void input_gssapi_errtok(int, u_int32_t, void *);
48
49/*
50 * We only support those mechanisms that we know about (ie ones that we know
51 * how to check local user kuserok and the like
52 */
53static int
54userauth_gssapi(Authctxt *authctxt)
55{
56 gss_OID_desc oid = {0, NULL};
57 Gssctxt *ctxt = NULL;
58 int mechs;
59 gss_OID_set supported;
60 int present;
61 OM_uint32 ms;
62 u_int len;
63 char *doid = NULL;
64
65 if (!authctxt->valid || authctxt->user == NULL)
66 return (0);
67
68 mechs = packet_get_int();
69 if (mechs == 0) {
70 debug("Mechanism negotiation is not supported");
71 return (0);
72 }
73
74 ssh_gssapi_supported_oids(&supported);
75 do {
76 mechs--;
77
78 if (doid)
79 xfree(doid);
80
81 doid = packet_get_string(&len);
82
83 if (doid[0] != SSH_GSS_OIDTYPE || doid[1] != len-2) {
84 logit("Mechanism OID received using the old encoding form");
85 oid.elements = doid;
86 oid.length = len;
87 } else {
88 oid.elements = doid + 2;
89 oid.length = len - 2;
90 }
91 gss_test_oid_set_member(&ms, &oid, supported, &present);
92 } while (mechs > 0 && !present);
93
94 gss_release_oid_set(&ms, &supported);
95
96 if (!present) {
97 xfree(doid);
98 return (0);
99 }
100
101 if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid))))
102 return (0);
103
104 authctxt->methoddata=(void *)ctxt;
105
106 packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
107
108 /* Return OID in same format as we received it*/
109 packet_put_string(doid, len);
110
111 packet_send();
112 xfree(doid);
113
114 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
115 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
116 authctxt->postponed = 1;
117
118 return (0);
119}
120
121static void
122input_gssapi_token(int type, u_int32_t plen, void *ctxt)
123{
124 Authctxt *authctxt = ctxt;
125 Gssctxt *gssctxt;
126 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
127 gss_buffer_desc recv_tok;
128 OM_uint32 maj_status, min_status;
129 u_int len;
130
131 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
132 fatal("No authentication or GSSAPI context");
133
134 gssctxt = authctxt->methoddata;
135 recv_tok.value = packet_get_string(&len);
136 recv_tok.length = len; /* u_int vs. size_t */
137
138 packet_check_eom();
139
140 maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
141 &send_tok, NULL));
142
143 xfree(recv_tok.value);
144
145 if (GSS_ERROR(maj_status)) {
146 if (send_tok.length != 0) {
147 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
148 packet_put_string(send_tok.value, send_tok.length);
149 packet_send();
150 }
151 authctxt->postponed = 0;
152 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
153 userauth_finish(authctxt, 0, "gssapi");
154 } else {
155 if (send_tok.length != 0) {
156 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
157 packet_put_string(send_tok.value, send_tok.length);
158 packet_send();
159 }
160 if (maj_status == GSS_S_COMPLETE) {
161 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
162 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
163 &input_gssapi_exchange_complete);
164 }
165 }
166
167 gss_release_buffer(&min_status, &send_tok);
168}
169
170static void
171input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
172{
173 Authctxt *authctxt = ctxt;
174 Gssctxt *gssctxt;
175 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
176 gss_buffer_desc recv_tok;
177 OM_uint32 maj_status;
178
179 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
180 fatal("No authentication or GSSAPI context");
181
182 gssctxt = authctxt->methoddata;
183 recv_tok.value = packet_get_string(&recv_tok.length);
184
185 packet_check_eom();
186
187 /* Push the error token into GSSAPI to see what it says */
188 maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
189 &send_tok, NULL));
190
191 xfree(recv_tok.value);
192
193 /* We can't return anything to the client, even if we wanted to */
194 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
195 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
196
197 /* The client will have already moved on to the next auth */
198
199 gss_release_buffer(&maj_status, &send_tok);
200}
201
202/*
203 * This is called when the client thinks we've completed authentication.
204 * It should only be enabled in the dispatch handler by the function above,
205 * which only enables it once the GSSAPI exchange is complete.
206 */
207
208static void
209input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
210{
211 Authctxt *authctxt = ctxt;
212 Gssctxt *gssctxt;
213 int authenticated;
214
215 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
216 fatal("No authentication or GSSAPI context");
217
218 gssctxt = authctxt->methoddata;
219
220 /*
221 * We don't need to check the status, because the stored credentials
222 * which userok uses are only populated once the context init step
223 * has returned complete.
224 */
225
226 packet_check_eom();
227
228 authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
229
230 authctxt->postponed = 0;
231 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
232 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
233 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
234 userauth_finish(authctxt, authenticated, "gssapi");
235}
236
237Authmethod method_gssapi = {
238 "gssapi",
239 userauth_gssapi,
240 &options.gss_authentication
241};
242
243#endif /* GSSAPI */