1 /* $OpenBSD: auth2-gss.c,v 1.12 2005/10/13 22:24:31 stevesk 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.
38 #include "monitor_wrap.h"
42 extern ServerOptions options;
44 static void ssh_gssapi_userauth_error(Gssctxt *ctxt);
45 static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
46 static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt);
47 static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
48 static void input_gssapi_errtok(int, u_int32_t, void *);
50 static int gssapi_with_mic = 1; /* flag to toggle "gssapi-with-mic" vs.
54 userauth_external(Authctxt *authctxt)
58 if (authctxt->valid && authctxt->user && authctxt->user[0]) {
59 return(PRIVSEP(ssh_gssapi_userok(authctxt->user)));
65 * The 'gssapi_keyex' userauth mechanism.
68 userauth_gsskeyex(Authctxt *authctxt)
70 int authenticated = 0;
72 gss_buffer_desc mic, gssbuf, gssbuf2;
75 mic.value = packet_get_string(&len);
80 ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
83 gssbuf.value = buffer_ptr(&b);
84 gssbuf.length = buffer_len(&b);
86 /* client may have used empty username to determine target
87 name from GSSAPI context */
88 ssh_gssapi_buildmic(&b2, "", authctxt->service, "gssapi-keyex");
90 gssbuf2.value = buffer_ptr(&b2);
91 gssbuf2.length = buffer_len(&b2);
93 /* gss_kex_context is NULL with privsep, so we can't check it here */
94 if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context,
96 !GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gss_kex_context,
98 if (authctxt->valid && authctxt->user && authctxt->user[0]) {
99 authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
107 return (authenticated);
111 * We only support those mechanisms that we know about (ie ones that we know
112 * how to check local user kuserok and the like)
115 userauth_gssapi(Authctxt *authctxt)
117 gss_OID_desc goid = {0, NULL};
118 Gssctxt *ctxt = NULL;
120 gss_OID_set supported;
126 /* authctxt->valid may be 0 if we haven't yet determined
127 username from gssapi context. */
129 if (authctxt->user == NULL)
132 mechs = packet_get_int();
134 debug("Mechanism negotiation is not supported");
138 ssh_gssapi_supported_oids(&supported);
146 doid = packet_get_string(&len);
148 if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
149 doid[1] == len - 2) {
150 goid.elements = doid + 2;
151 goid.length = len - 2;
152 gss_test_oid_set_member(&ms, &goid, supported,
155 logit("Badly formed OID received");
157 } while (mechs > 0 && !present);
159 gss_release_oid_set(&ms, &supported);
163 authctxt->server_caused_failure = 1;
167 if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
169 authctxt->server_caused_failure = 1;
173 authctxt->methoddata = (void *)ctxt;
175 packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
177 /* Return the OID that we received */
178 packet_put_string(doid, len);
183 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
184 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
185 authctxt->postponed = 1;
191 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
193 Authctxt *authctxt = ctxt;
195 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
196 gss_buffer_desc recv_tok;
197 OM_uint32 maj_status, min_status, flags=0;
200 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
201 fatal("No authentication or GSSAPI context");
203 gssctxt = authctxt->methoddata;
204 recv_tok.value = packet_get_string(&len);
205 recv_tok.length = len; /* u_int vs. size_t */
209 maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
212 xfree(recv_tok.value);
214 if (GSS_ERROR(maj_status)) {
215 ssh_gssapi_userauth_error(gssctxt);
216 if (send_tok.length != 0) {
217 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
218 packet_put_string(send_tok.value, send_tok.length);
221 authctxt->postponed = 0;
222 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
223 userauth_finish(authctxt, 0,
224 gssapi_with_mic ? "gssapi-with-mic" :
227 if (send_tok.length != 0) {
228 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
229 packet_put_string(send_tok.value, send_tok.length);
232 if (maj_status == GSS_S_COMPLETE) {
233 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
234 if (flags & GSS_C_INTEG_FLAG && gssapi_with_mic)
235 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC,
239 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
240 &input_gssapi_exchange_complete);
244 gss_release_buffer(&min_status, &send_tok);
248 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
250 Authctxt *authctxt = ctxt;
252 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
253 gss_buffer_desc recv_tok;
254 OM_uint32 maj_status;
257 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
258 fatal("No authentication or GSSAPI context");
260 gssctxt = authctxt->methoddata;
261 recv_tok.value = packet_get_string(&len);
262 recv_tok.length = len;
266 /* Push the error token into GSSAPI to see what it says */
267 maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
270 xfree(recv_tok.value);
272 /* We can't return anything to the client, even if we wanted to */
273 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
274 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
276 /* The client will have already moved on to the next auth */
278 gss_release_buffer(&maj_status, &send_tok);
282 gssapi_set_implicit_username(Authctxt *authctxt)
284 if ((authctxt->user == NULL) || (authctxt->user[0] == '\0')) {
286 PRIVSEP(ssh_gssapi_localname(&lname));
287 if (lname && lname[0] != '\0') {
288 if (authctxt->user) xfree(authctxt->user);
289 authctxt->user = lname;
290 debug("set username to %s from gssapi context", lname);
291 authctxt->pw = PRIVSEP(getpwnamallow(authctxt->user));
296 debug("failed to set username from gssapi context");
297 packet_send_debug("failed to set username from gssapi context");
303 PRIVSEP(start_pam(authctxt));
309 * This is called when the client thinks we've completed authentication.
310 * It should only be enabled in the dispatch handler by the function above,
311 * which only enables it once the GSSAPI exchange is complete.
315 input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
317 Authctxt *authctxt = ctxt;
321 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
322 fatal("No authentication or GSSAPI context");
324 gssapi_set_implicit_username(authctxt);
326 gssctxt = authctxt->methoddata;
329 * We don't need to check the status, because we're only enabled in
330 * the dispatcher once the exchange is complete
335 /* user should be set if valid but we double-check here */
336 if (authctxt->valid && authctxt->user && authctxt->user[0]) {
337 authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
342 authctxt->postponed = 0;
343 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
344 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
345 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
346 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
347 userauth_finish(authctxt, authenticated,
348 gssapi_with_mic ? "gssapi-with-mic" : "gssapi");
352 userauth_gssapi_with_mic(Authctxt *authctxt)
355 return userauth_gssapi(authctxt);
359 userauth_gssapi_without_mic(Authctxt *authctxt)
362 return userauth_gssapi(authctxt);
366 input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
368 Authctxt *authctxt = ctxt;
370 int authenticated = 0;
372 gss_buffer_desc mic, gssbuf;
375 if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
376 fatal("No authentication or GSSAPI context");
378 gssapi_set_implicit_username(authctxt);
380 gssctxt = authctxt->methoddata;
382 mic.value = packet_get_string(&len);
385 ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
388 gssbuf.value = buffer_ptr(&b);
389 gssbuf.length = buffer_len(&b);
391 if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
392 if (authctxt->valid && authctxt->user && authctxt->user[0]) {
393 authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
398 logit("GSSAPI MIC check failed");
403 authctxt->postponed = 0;
404 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
405 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
406 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
407 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
408 userauth_finish(authctxt, authenticated, "gssapi-with-mic");
411 static void ssh_gssapi_userauth_error(Gssctxt *ctxt) {
415 errstr=PRIVSEP(ssh_gssapi_last_error(ctxt,&maj,&min));
417 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERROR);
420 packet_put_cstring(errstr);
421 packet_put_cstring("");
428 Authmethod method_external = {
431 &options.gss_authentication
434 Authmethod method_gsskeyex = {
437 &options.gss_authentication
440 Authmethod method_gssapi = {
442 userauth_gssapi_with_mic,
443 &options.gss_authentication
446 Authmethod method_gssapi_compat = {
448 userauth_gssapi_without_mic,
449 &options.gss_authentication