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Darren Tuckera627d422013-06-02 07:31:17 +10001/* $OpenBSD: auth2-gss.c,v 1.20 2013/05/17 00:13:13 djm 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
Darren Tucker8c6feda2006-08-05 15:24:59 +100029#ifdef GSSAPI
30
Damien Millerd7834352006-08-05 12:39:39 +100031#include <sys/types.h>
Darren Tucker0efd1552003-08-26 11:49:55 +100032
Damien Millerded319c2006-09-01 15:38:36 +100033#include <stdarg.h>
34
Damien Millerd7834352006-08-05 12:39:39 +100035#include "xmalloc.h"
36#include "key.h"
37#include "hostfile.h"
Darren Tucker0efd1552003-08-26 11:49:55 +100038#include "auth.h"
39#include "ssh2.h"
Darren Tucker0efd1552003-08-26 11:49:55 +100040#include "log.h"
41#include "dispatch.h"
Damien Millerd7834352006-08-05 12:39:39 +100042#include "buffer.h"
Darren Tucker0efd1552003-08-26 11:49:55 +100043#include "servconf.h"
Darren Tucker0efd1552003-08-26 11:49:55 +100044#include "packet.h"
Darren Tucker0efd1552003-08-26 11:49:55 +100045#include "ssh-gss.h"
Damien Millerd7834352006-08-05 12:39:39 +100046#include "monitor_wrap.h"
Darren Tucker0efd1552003-08-26 11:49:55 +100047
48extern ServerOptions options;
49
50static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
Damien Miller0425d402003-11-17 22:18:21 +110051static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt);
Darren Tucker0efd1552003-08-26 11:49:55 +100052static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
53static void input_gssapi_errtok(int, u_int32_t, void *);
54
55/*
56 * We only support those mechanisms that we know about (ie ones that we know
Damien Miller6fd6def2005-11-05 15:07:05 +110057 * how to check local user kuserok and the like)
Darren Tucker0efd1552003-08-26 11:49:55 +100058 */
59static int
60userauth_gssapi(Authctxt *authctxt)
61{
Darren Tucker3f9fdc72004-06-22 12:56:01 +100062 gss_OID_desc goid = {0, NULL};
Darren Tucker0efd1552003-08-26 11:49:55 +100063 Gssctxt *ctxt = NULL;
64 int mechs;
65 gss_OID_set supported;
66 int present;
67 OM_uint32 ms;
68 u_int len;
Damien Millereccb9de2005-06-17 12:59:34 +100069 u_char *doid = NULL;
Darren Tucker0efd1552003-08-26 11:49:55 +100070
71 if (!authctxt->valid || authctxt->user == NULL)
72 return (0);
73
74 mechs = packet_get_int();
75 if (mechs == 0) {
76 debug("Mechanism negotiation is not supported");
77 return (0);
78 }
79
80 ssh_gssapi_supported_oids(&supported);
81 do {
82 mechs--;
83
Darren Tuckera627d422013-06-02 07:31:17 +100084 free(doid);
Darren Tucker0efd1552003-08-26 11:49:55 +100085
Darren Tucker655a5e02003-11-03 20:09:03 +110086 present = 0;
Darren Tucker0efd1552003-08-26 11:49:55 +100087 doid = packet_get_string(&len);
88
Damien Miller0dc1bef2005-07-17 17:22:45 +100089 if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
90 doid[1] == len - 2) {
Darren Tucker3f9fdc72004-06-22 12:56:01 +100091 goid.elements = doid + 2;
92 goid.length = len - 2;
93 gss_test_oid_set_member(&ms, &goid, supported,
Darren Tucker655a5e02003-11-03 20:09:03 +110094 &present);
Darren Tucker0efd1552003-08-26 11:49:55 +100095 } else {
Darren Tucker655a5e02003-11-03 20:09:03 +110096 logit("Badly formed OID received");
Darren Tucker0efd1552003-08-26 11:49:55 +100097 }
Darren Tucker0efd1552003-08-26 11:49:55 +100098 } while (mechs > 0 && !present);
99
100 gss_release_oid_set(&ms, &supported);
101
102 if (!present) {
Darren Tuckera627d422013-06-02 07:31:17 +1000103 free(doid);
Damien Miller3fcdfd52011-05-05 14:04:11 +1000104 authctxt->server_caused_failure = 1;
Darren Tucker0efd1552003-08-26 11:49:55 +1000105 return (0);
106 }
107
Darren Tucker3f9fdc72004-06-22 12:56:01 +1000108 if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
Damien Millerf23c0962006-03-26 00:04:53 +1100109 if (ctxt != NULL)
110 ssh_gssapi_delete_ctx(&ctxt);
Darren Tuckera627d422013-06-02 07:31:17 +1000111 free(doid);
Damien Miller3fcdfd52011-05-05 14:04:11 +1000112 authctxt->server_caused_failure = 1;
Darren Tucker0efd1552003-08-26 11:49:55 +1000113 return (0);
Damien Miller982d3262003-09-02 22:59:01 +1000114 }
Darren Tucker0efd1552003-08-26 11:49:55 +1000115
Damien Miller6fd6def2005-11-05 15:07:05 +1100116 authctxt->methoddata = (void *)ctxt;
Darren Tucker0efd1552003-08-26 11:49:55 +1000117
118 packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
119
Darren Tucker655a5e02003-11-03 20:09:03 +1100120 /* Return the OID that we received */
Darren Tucker0efd1552003-08-26 11:49:55 +1000121 packet_put_string(doid, len);
122
123 packet_send();
Darren Tuckera627d422013-06-02 07:31:17 +1000124 free(doid);
Darren Tucker0efd1552003-08-26 11:49:55 +1000125
126 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
127 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
128 authctxt->postponed = 1;
129
130 return (0);
131}
132
133static void
134input_gssapi_token(int type, u_int32_t plen, void *ctxt)
135{
136 Authctxt *authctxt = ctxt;
137 Gssctxt *gssctxt;
138 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
139 gss_buffer_desc recv_tok;
Damien Miller0425d402003-11-17 22:18:21 +1100140 OM_uint32 maj_status, min_status, flags;
Darren Tucker0efd1552003-08-26 11:49:55 +1000141 u_int len;
142
143 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
144 fatal("No authentication or GSSAPI context");
145
146 gssctxt = authctxt->methoddata;
147 recv_tok.value = packet_get_string(&len);
148 recv_tok.length = len; /* u_int vs. size_t */
149
150 packet_check_eom();
151
152 maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
Damien Miller0425d402003-11-17 22:18:21 +1100153 &send_tok, &flags));
Darren Tucker0efd1552003-08-26 11:49:55 +1000154
Darren Tuckera627d422013-06-02 07:31:17 +1000155 free(recv_tok.value);
Darren Tucker0efd1552003-08-26 11:49:55 +1000156
157 if (GSS_ERROR(maj_status)) {
158 if (send_tok.length != 0) {
159 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
160 packet_put_string(send_tok.value, send_tok.length);
161 packet_send();
162 }
163 authctxt->postponed = 0;
164 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
Damien Miller15b05cf2012-12-03 09:53:20 +1100165 userauth_finish(authctxt, 0, "gssapi-with-mic", NULL);
Darren Tucker0efd1552003-08-26 11:49:55 +1000166 } else {
167 if (send_tok.length != 0) {
168 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
169 packet_put_string(send_tok.value, send_tok.length);
170 packet_send();
171 }
172 if (maj_status == GSS_S_COMPLETE) {
173 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
Damien Miller0425d402003-11-17 22:18:21 +1100174 if (flags & GSS_C_INTEG_FLAG)
175 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC,
176 &input_gssapi_mic);
177 else
178 dispatch_set(
179 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
180 &input_gssapi_exchange_complete);
Darren Tucker0efd1552003-08-26 11:49:55 +1000181 }
182 }
183
184 gss_release_buffer(&min_status, &send_tok);
185}
186
187static void
188input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
189{
190 Authctxt *authctxt = ctxt;
191 Gssctxt *gssctxt;
192 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
193 gss_buffer_desc recv_tok;
194 OM_uint32 maj_status;
Damien Miller55c47ed2003-09-02 22:14:07 +1000195 u_int len;
Darren Tucker0efd1552003-08-26 11:49:55 +1000196
197 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
198 fatal("No authentication or GSSAPI context");
199
200 gssctxt = authctxt->methoddata;
Damien Miller55c47ed2003-09-02 22:14:07 +1000201 recv_tok.value = packet_get_string(&len);
202 recv_tok.length = len;
Darren Tucker0efd1552003-08-26 11:49:55 +1000203
204 packet_check_eom();
205
206 /* Push the error token into GSSAPI to see what it says */
207 maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
208 &send_tok, NULL));
209
Darren Tuckera627d422013-06-02 07:31:17 +1000210 free(recv_tok.value);
Darren Tucker0efd1552003-08-26 11:49:55 +1000211
212 /* We can't return anything to the client, even if we wanted to */
213 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
214 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
215
216 /* The client will have already moved on to the next auth */
217
218 gss_release_buffer(&maj_status, &send_tok);
219}
220
221/*
222 * This is called when the client thinks we've completed authentication.
223 * It should only be enabled in the dispatch handler by the function above,
224 * which only enables it once the GSSAPI exchange is complete.
225 */
226
227static void
228input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
229{
230 Authctxt *authctxt = ctxt;
Darren Tucker0efd1552003-08-26 11:49:55 +1000231 int authenticated;
232
233 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
234 fatal("No authentication or GSSAPI context");
235
Darren Tucker0efd1552003-08-26 11:49:55 +1000236 /*
Damien Miller0425d402003-11-17 22:18:21 +1100237 * We don't need to check the status, because we're only enabled in
238 * the dispatcher once the exchange is complete
Darren Tucker0efd1552003-08-26 11:49:55 +1000239 */
240
241 packet_check_eom();
242
243 authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
244
245 authctxt->postponed = 0;
246 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
247 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
Damien Miller0425d402003-11-17 22:18:21 +1100248 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
Darren Tucker0efd1552003-08-26 11:49:55 +1000249 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
Damien Miller15b05cf2012-12-03 09:53:20 +1100250 userauth_finish(authctxt, authenticated, "gssapi-with-mic", NULL);
Damien Miller0425d402003-11-17 22:18:21 +1100251}
252
253static void
254input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
255{
256 Authctxt *authctxt = ctxt;
257 Gssctxt *gssctxt;
258 int authenticated = 0;
259 Buffer b;
260 gss_buffer_desc mic, gssbuf;
261 u_int len;
Damien Miller787b2ec2003-11-21 23:56:47 +1100262
Damien Miller0425d402003-11-17 22:18:21 +1100263 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
264 fatal("No authentication or GSSAPI context");
Damien Miller787b2ec2003-11-21 23:56:47 +1100265
Damien Miller0425d402003-11-17 22:18:21 +1100266 gssctxt = authctxt->methoddata;
Damien Miller787b2ec2003-11-21 23:56:47 +1100267
Damien Miller0425d402003-11-17 22:18:21 +1100268 mic.value = packet_get_string(&len);
269 mic.length = len;
Damien Miller787b2ec2003-11-21 23:56:47 +1100270
Damien Miller0425d402003-11-17 22:18:21 +1100271 ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
272 "gssapi-with-mic");
Damien Miller787b2ec2003-11-21 23:56:47 +1100273
Damien Miller0425d402003-11-17 22:18:21 +1100274 gssbuf.value = buffer_ptr(&b);
275 gssbuf.length = buffer_len(&b);
Damien Miller787b2ec2003-11-21 23:56:47 +1100276
Damien Miller0425d402003-11-17 22:18:21 +1100277 if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
278 authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
279 else
280 logit("GSSAPI MIC check failed");
281
282 buffer_free(&b);
Darren Tuckera627d422013-06-02 07:31:17 +1000283 free(mic.value);
Damien Miller787b2ec2003-11-21 23:56:47 +1100284
Damien Miller0425d402003-11-17 22:18:21 +1100285 authctxt->postponed = 0;
286 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
287 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
288 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
289 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
Damien Miller15b05cf2012-12-03 09:53:20 +1100290 userauth_finish(authctxt, authenticated, "gssapi-with-mic", NULL);
Darren Tucker0efd1552003-08-26 11:49:55 +1000291}
292
293Authmethod method_gssapi = {
Damien Miller0425d402003-11-17 22:18:21 +1100294 "gssapi-with-mic",
Darren Tucker0efd1552003-08-26 11:49:55 +1000295 userauth_gssapi,
296 &options.gss_authentication
297};
Darren Tucker8c6feda2006-08-05 15:24:59 +1000298
299#endif /* GSSAPI */