1 /* $OpenBSD: auth2-gss.c,v 1.16 2007/10/29 00:52:45 dtucker Exp $ */
4 * Copyright (c) 2001-2007 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.
31 #include <sys/types.h>
46 #include "monitor_wrap.h"
48 extern ServerOptions options;
50 static void ssh_gssapi_userauth_error(Gssctxt *ctxt);
51 static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
52 static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt);
53 static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
54 static void input_gssapi_errtok(int, u_int32_t, void *);
56 static int gssapi_with_mic = 1; /* flag to toggle "gssapi-with-mic" vs.
60 userauth_external(Authctxt *authctxt)
64 if (authctxt->valid && authctxt->user && authctxt->user[0]) {
65 return(PRIVSEP(ssh_gssapi_userok(authctxt->user, authctxt->pw)));
71 * The 'gssapi_keyex' userauth mechanism.
74 userauth_gsskeyex(Authctxt *authctxt)
76 int authenticated = 0;
78 gss_buffer_desc mic, gssbuf, gssbuf2;
81 mic.value = packet_get_string(&len);
86 ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
89 gssbuf.value = buffer_ptr(&b);
90 gssbuf.length = buffer_len(&b);
92 /* client may have used empty username to determine target
93 name from GSSAPI context */
94 ssh_gssapi_buildmic(&b2, "", authctxt->service, "gssapi-keyex");
96 gssbuf2.value = buffer_ptr(&b2);
97 gssbuf2.length = buffer_len(&b2);
99 /* gss_kex_context is NULL with privsep, so we can't check it here */
100 if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context,
102 !GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context,
104 if (authctxt->valid && authctxt->user && authctxt->user[0]) {
105 authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user,
114 return (authenticated);
118 * We only support those mechanisms that we know about (ie ones that we know
119 * how to check local user kuserok and the like)
122 userauth_gssapi(Authctxt *authctxt)
124 gss_OID_desc goid = {0, NULL};
125 Gssctxt *ctxt = NULL;
127 gss_OID_set supported;
133 /* authctxt->valid may be 0 if we haven't yet determined
134 username from gssapi context. */
136 if (authctxt->user == NULL)
139 mechs = packet_get_int();
141 debug("Mechanism negotiation is not supported");
145 ssh_gssapi_supported_oids(&supported);
153 doid = packet_get_string(&len);
155 if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
156 doid[1] == len - 2) {
157 goid.elements = doid + 2;
158 goid.length = len - 2;
159 gss_test_oid_set_member(&ms, &goid, supported,
162 logit("Badly formed OID received");
164 } while (mechs > 0 && !present);
166 gss_release_oid_set(&ms, &supported);
170 authctxt->server_caused_failure = 1;
174 if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
176 ssh_gssapi_delete_ctx(&ctxt);
178 authctxt->server_caused_failure = 1;
182 authctxt->methoddata = (void *)ctxt;
184 packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
186 /* Return the OID that we received */
187 packet_put_string(doid, len);
192 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
193 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
194 authctxt->postponed = 1;
200 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
202 Authctxt *authctxt = ctxt;
204 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
205 gss_buffer_desc recv_tok;
206 OM_uint32 maj_status, min_status, flags=0;
209 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
210 fatal("No authentication or GSSAPI context");
212 gssctxt = authctxt->methoddata;
213 recv_tok.value = packet_get_string(&len);
214 recv_tok.length = len; /* u_int vs. size_t */
218 maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
221 xfree(recv_tok.value);
223 if (GSS_ERROR(maj_status)) {
224 ssh_gssapi_userauth_error(gssctxt);
225 if (send_tok.length != 0) {
226 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
227 packet_put_string(send_tok.value, send_tok.length);
230 authctxt->postponed = 0;
231 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
232 userauth_finish(authctxt, 0,
233 gssapi_with_mic ? "gssapi-with-mic" :
236 if (send_tok.length != 0) {
237 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
238 packet_put_string(send_tok.value, send_tok.length);
241 if (maj_status == GSS_S_COMPLETE) {
242 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
243 if (flags & GSS_C_INTEG_FLAG && gssapi_with_mic)
244 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC,
248 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
249 &input_gssapi_exchange_complete);
253 gss_release_buffer(&min_status, &send_tok);
257 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
259 Authctxt *authctxt = ctxt;
261 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
262 gss_buffer_desc recv_tok;
263 OM_uint32 maj_status;
266 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
267 fatal("No authentication or GSSAPI context");
269 gssctxt = authctxt->methoddata;
270 recv_tok.value = packet_get_string(&len);
271 recv_tok.length = len;
275 /* Push the error token into GSSAPI to see what it says */
276 maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
279 xfree(recv_tok.value);
281 /* We can't return anything to the client, even if we wanted to */
282 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
283 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
285 /* The client will have already moved on to the next auth */
287 gss_release_buffer(&maj_status, &send_tok);
291 gssapi_set_username(Authctxt *authctxt)
295 if ((authctxt->user == NULL) || (authctxt->user[0] == '\0')) {
296 PRIVSEP(ssh_gssapi_localname(&lname));
297 if (lname && lname[0] != '\0') {
298 if (authctxt->user) xfree(authctxt->user);
299 authctxt->user = lname;
300 debug("set username to %s from gssapi context", lname);
301 authctxt->pw = PRIVSEP(getpwnamallow(authctxt->user));
306 PRIVSEP(start_pam(authctxt));
310 debug("failed to set username from gssapi context");
311 packet_send_debug("failed to set username from gssapi context");
317 * This is called when the client thinks we've completed authentication.
318 * It should only be enabled in the dispatch handler by the function above,
319 * which only enables it once the GSSAPI exchange is complete.
323 input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
325 Authctxt *authctxt = ctxt;
329 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
330 fatal("No authentication or GSSAPI context");
332 gssapi_set_username(authctxt);
334 gssctxt = authctxt->methoddata;
337 * We don't need to check the status, because we're only enabled in
338 * the dispatcher once the exchange is complete
343 /* user should be set if valid but we double-check here */
344 if (authctxt->valid && authctxt->user && authctxt->user[0]) {
345 authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user,
351 authctxt->postponed = 0;
352 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
353 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
354 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
355 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
356 userauth_finish(authctxt, authenticated,
357 gssapi_with_mic ? "gssapi-with-mic" : "gssapi");
361 userauth_gssapi_with_mic(Authctxt *authctxt)
364 return userauth_gssapi(authctxt);
368 userauth_gssapi_without_mic(Authctxt *authctxt)
371 return userauth_gssapi(authctxt);
375 input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
377 Authctxt *authctxt = ctxt;
379 int authenticated = 0;
381 gss_buffer_desc mic, gssbuf;
384 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
385 fatal("No authentication or GSSAPI context");
387 gssctxt = authctxt->methoddata;
389 mic.value = packet_get_string(&len);
392 ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
395 gssbuf.value = buffer_ptr(&b);
396 gssbuf.length = buffer_len(&b);
398 gssapi_set_username(authctxt);
400 if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
401 if (authctxt->valid && authctxt->user && authctxt->user[0]) {
403 PRIVSEP(ssh_gssapi_userok(authctxt->user, authctxt->pw));
408 logit("GSSAPI MIC check failed");
413 authctxt->postponed = 0;
414 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
415 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
416 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
417 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
418 userauth_finish(authctxt, authenticated, "gssapi-with-mic");
421 static void ssh_gssapi_userauth_error(Gssctxt *ctxt) {
425 errstr=PRIVSEP(ssh_gssapi_last_error(ctxt,&maj,&min));
427 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERROR);
430 packet_put_cstring(errstr);
431 packet_put_cstring("");
438 Authmethod method_external = {
441 &options.gss_authentication
444 Authmethod method_gsskeyex = {
447 &options.gss_authentication
450 Authmethod method_gssapi = {
452 userauth_gssapi_with_mic,
453 &options.gss_authentication
456 Authmethod method_gssapi_compat = {
458 userauth_gssapi_without_mic,
459 &options.gss_authentication