blob: 75b94b0097398f2d881e2aa0f50a923405644a24 [file] [log] [blame]
Damien Miller982d3262003-09-02 22:59:01 +10001/* $OpenBSD: auth2-gss.c,v 1.3 2003/09/01 20:44:54 markus Exp $ */
Darren Tucker0efd1552003-08-26 11:49:55 +10002
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
Damien Miller982d3262003-09-02 22:59:01 +1000101 if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid)))) {
102 xfree(doid);
Darren Tucker0efd1552003-08-26 11:49:55 +1000103 return (0);
Damien Miller982d3262003-09-02 22:59:01 +1000104 }
Darren Tucker0efd1552003-08-26 11:49:55 +1000105
106 authctxt->methoddata=(void *)ctxt;
107
108 packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
109
110 /* Return OID in same format as we received it*/
111 packet_put_string(doid, len);
112
113 packet_send();
114 xfree(doid);
115
116 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
117 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
118 authctxt->postponed = 1;
119
120 return (0);
121}
122
123static void
124input_gssapi_token(int type, u_int32_t plen, void *ctxt)
125{
126 Authctxt *authctxt = ctxt;
127 Gssctxt *gssctxt;
128 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
129 gss_buffer_desc recv_tok;
130 OM_uint32 maj_status, min_status;
131 u_int len;
132
133 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
134 fatal("No authentication or GSSAPI context");
135
136 gssctxt = authctxt->methoddata;
137 recv_tok.value = packet_get_string(&len);
138 recv_tok.length = len; /* u_int vs. size_t */
139
140 packet_check_eom();
141
142 maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
143 &send_tok, NULL));
144
145 xfree(recv_tok.value);
146
147 if (GSS_ERROR(maj_status)) {
148 if (send_tok.length != 0) {
149 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
150 packet_put_string(send_tok.value, send_tok.length);
151 packet_send();
152 }
153 authctxt->postponed = 0;
154 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
155 userauth_finish(authctxt, 0, "gssapi");
156 } else {
157 if (send_tok.length != 0) {
158 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
159 packet_put_string(send_tok.value, send_tok.length);
160 packet_send();
161 }
162 if (maj_status == GSS_S_COMPLETE) {
163 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
164 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
165 &input_gssapi_exchange_complete);
166 }
167 }
168
169 gss_release_buffer(&min_status, &send_tok);
170}
171
172static void
173input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
174{
175 Authctxt *authctxt = ctxt;
176 Gssctxt *gssctxt;
177 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
178 gss_buffer_desc recv_tok;
179 OM_uint32 maj_status;
Damien Miller55c47ed2003-09-02 22:14:07 +1000180 u_int len;
Darren Tucker0efd1552003-08-26 11:49:55 +1000181
182 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
183 fatal("No authentication or GSSAPI context");
184
185 gssctxt = authctxt->methoddata;
Damien Miller55c47ed2003-09-02 22:14:07 +1000186 recv_tok.value = packet_get_string(&len);
187 recv_tok.length = len;
Darren Tucker0efd1552003-08-26 11:49:55 +1000188
189 packet_check_eom();
190
191 /* Push the error token into GSSAPI to see what it says */
192 maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
193 &send_tok, NULL));
194
195 xfree(recv_tok.value);
196
197 /* We can't return anything to the client, even if we wanted to */
198 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
199 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
200
201 /* The client will have already moved on to the next auth */
202
203 gss_release_buffer(&maj_status, &send_tok);
204}
205
206/*
207 * This is called when the client thinks we've completed authentication.
208 * It should only be enabled in the dispatch handler by the function above,
209 * which only enables it once the GSSAPI exchange is complete.
210 */
211
212static void
213input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
214{
215 Authctxt *authctxt = ctxt;
216 Gssctxt *gssctxt;
217 int authenticated;
218
219 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
220 fatal("No authentication or GSSAPI context");
221
222 gssctxt = authctxt->methoddata;
223
224 /*
225 * We don't need to check the status, because the stored credentials
226 * which userok uses are only populated once the context init step
227 * has returned complete.
228 */
229
230 packet_check_eom();
231
232 authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
233
234 authctxt->postponed = 0;
235 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
236 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
237 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
238 userauth_finish(authctxt, authenticated, "gssapi");
239}
240
241Authmethod method_gssapi = {
242 "gssapi",
243 userauth_gssapi,
244 &options.gss_authentication
245};
246
247#endif /* GSSAPI */