1 /* $OpenBSD: auth2-gss.c,v 1.7 2003/11/21 11:57:03 djm Exp $ */
4 * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
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.
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.
39 #include "monitor_wrap.h"
43 extern ServerOptions options;
45 static void ssh_gssapi_userauth_error(Gssctxt *ctxt);
46 static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
47 static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt);
48 static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
49 static void input_gssapi_errtok(int, u_int32_t, void *);
51 static int gssapi_with_mic = 1; /* flag to toggle "gssapi-with-mic" vs.
55 userauth_external(Authctxt *authctxt)
59 if (authctxt->valid && authctxt->user &&
60 strcmp(authctxt->user, "") != 0) {
61 return(PRIVSEP(ssh_gssapi_userok(authctxt->user)));
67 * We only support those mechanisms that we know about (ie ones that we know
68 * how to check local user kuserok and the like
71 userauth_gssapi(Authctxt *authctxt)
73 gss_OID_desc oid = {0, NULL};
76 gss_OID_set supported;
82 if (authctxt->user == NULL)
85 mechs = packet_get_int();
87 debug("Mechanism negotiation is not supported");
91 ssh_gssapi_supported_oids(&supported);
99 doid = packet_get_string(&len);
101 if (doid[0] != SSH_GSS_OIDTYPE || doid[1] != len-2) {
102 logit("Mechanism OID received using the old encoding form");
106 oid.elements = doid + 2;
107 oid.length = len - 2;
109 gss_test_oid_set_member(&ms, &oid, supported, &present);
110 } while (mechs > 0 && !present);
112 gss_release_oid_set(&ms, &supported);
119 if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid)))) {
124 authctxt->methoddata=(void *)ctxt;
126 packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
128 /* Return the OID that we received */
129 packet_put_string(doid, len);
134 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
135 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
136 authctxt->postponed = 1;
142 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
144 Authctxt *authctxt = ctxt;
146 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
147 gss_buffer_desc recv_tok;
148 OM_uint32 maj_status, min_status, flags=0;
151 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
152 fatal("No authentication or GSSAPI context");
154 gssctxt = authctxt->methoddata;
155 recv_tok.value = packet_get_string(&len);
156 recv_tok.length = len; /* u_int vs. size_t */
160 maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
163 xfree(recv_tok.value);
165 if (GSS_ERROR(maj_status)) {
166 ssh_gssapi_userauth_error(gssctxt);
167 if (send_tok.length != 0) {
168 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
169 packet_put_string(send_tok.value, send_tok.length);
172 authctxt->postponed = 0;
173 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
174 userauth_finish(authctxt, 0,
175 gssapi_with_mic ? "gssapi-with-mic" :
178 if (send_tok.length != 0) {
179 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
180 packet_put_string(send_tok.value, send_tok.length);
183 if (maj_status == GSS_S_COMPLETE) {
184 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
185 if (flags & GSS_C_INTEG_FLAG && gssapi_with_mic)
186 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC,
190 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
191 &input_gssapi_exchange_complete);
195 gss_release_buffer(&min_status, &send_tok);
199 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
201 Authctxt *authctxt = ctxt;
203 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
204 gss_buffer_desc recv_tok;
205 OM_uint32 maj_status;
208 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
209 fatal("No authentication or GSSAPI context");
211 gssctxt = authctxt->methoddata;
212 recv_tok.value = packet_get_string(&len);
213 recv_tok.length = len;
217 /* Push the error token into GSSAPI to see what it says */
218 maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
221 xfree(recv_tok.value);
223 /* We can't return anything to the client, even if we wanted to */
224 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
225 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
227 /* The client will have already moved on to the next auth */
229 gss_release_buffer(&maj_status, &send_tok);
233 gssapi_set_implicit_username(Authctxt *authctxt)
235 if ((authctxt->user == NULL) || (strcmp(authctxt->user, "") == 0)) {
237 PRIVSEP(ssh_gssapi_localname(&lname));
238 if (lname && lname[0] != '\0') {
239 xfree(authctxt->user);
240 authctxt->user = lname;
241 debug("set username to %s from gssapi context", lname);
242 authctxt->pw = PRIVSEP(getpwnamallow(authctxt->user));
247 debug("failed to set username from gssapi context");
253 PRIVSEP(start_pam(authctxt));
259 * This is called when the client thinks we've completed authentication.
260 * It should only be enabled in the dispatch handler by the function above,
261 * which only enables it once the GSSAPI exchange is complete.
265 input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
267 Authctxt *authctxt = ctxt;
271 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
272 fatal("No authentication or GSSAPI context");
274 gssapi_set_implicit_username(authctxt);
276 gssctxt = authctxt->methoddata;
279 * We don't need to check the status, because we're only enabled in
280 * the dispatcher once the exchange is complete
285 if (authctxt->valid && strcmp(authctxt->user, "") != 0) {
286 authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
291 authctxt->postponed = 0;
292 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
293 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
294 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
295 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
296 userauth_finish(authctxt, authenticated,
297 gssapi_with_mic ? "gssapi-with-mic" : "gssapi");
301 userauth_gssapi_with_mic(Authctxt *authctxt)
304 return userauth_gssapi(authctxt);
308 userauth_gssapi_without_mic(Authctxt *authctxt)
311 return userauth_gssapi(authctxt);
315 input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
317 Authctxt *authctxt = ctxt;
319 int authenticated = 0;
321 gss_buffer_desc mic, gssbuf;
324 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
325 fatal("No authentication or GSSAPI context");
327 gssapi_set_implicit_username(authctxt);
329 gssctxt = authctxt->methoddata;
331 mic.value = packet_get_string(&len);
334 ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
337 gssbuf.value = buffer_ptr(&b);
338 gssbuf.length = buffer_len(&b);
340 if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
341 if (authctxt->valid && strcmp(authctxt->user, "") != 0) {
342 authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
347 logit("GSSAPI MIC check failed");
352 authctxt->postponed = 0;
353 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
354 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
355 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
356 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
357 userauth_finish(authctxt, authenticated, "gssapi-with-mic");
360 static void ssh_gssapi_userauth_error(Gssctxt *ctxt) {
364 errstr=PRIVSEP(ssh_gssapi_last_error(ctxt,&maj,&min));
366 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERROR);
369 packet_put_cstring(errstr);
370 packet_put_cstring("");
377 Authmethod method_external = {
380 &options.gss_authentication
383 Authmethod method_gssapi = {
385 userauth_gssapi_with_mic,
386 &options.gss_authentication
389 Authmethod method_gssapi_compat = {
391 userauth_gssapi_without_mic,
392 &options.gss_authentication