[openssh.git] / auth2-gss.c

/*	$OpenBSD: auth2-gss.c,v 1.1 2003/08/22 10:56:08 markus Exp $	*/

/*
 * Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "includes.h"

#ifdef GSSAPI

#include "auth.h"
#include "ssh2.h"
#include "xmalloc.h"
#include "log.h"
#include "dispatch.h"
#include "servconf.h"
#include "compat.h"
#include "packet.h"
#include "monitor_wrap.h"

#include "ssh-gss.h"

extern ServerOptions options;

static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
static void input_gssapi_errtok(int, u_int32_t, void *);

/*
 * We only support those mechanisms that we know about (ie ones that we know
 * how to check local user kuserok and the like
 */
static int
userauth_gssapi(Authctxt *authctxt)
{
	gss_OID_desc oid = {0, NULL};
	Gssctxt *ctxt = NULL;
	int mechs;
	gss_OID_set supported;
	int present;
	OM_uint32 ms;
	u_int len;
	char *doid = NULL;

	if (!authctxt->valid || authctxt->user == NULL)
		return (0);

	mechs = packet_get_int();
	if (mechs == 0) {
		debug("Mechanism negotiation is not supported");
		return (0);
	}

	ssh_gssapi_supported_oids(&supported);
	do {
		mechs--;

		if (doid)
			xfree(doid);

		doid = packet_get_string(&len);

		if (doid[0] != SSH_GSS_OIDTYPE || doid[1] != len-2) {
			logit("Mechanism OID received using the old encoding form");
			oid.elements = doid;
			oid.length = len;
		} else {
			oid.elements = doid + 2;
			oid.length   = len - 2;
		}
		gss_test_oid_set_member(&ms, &oid, supported, &present);
	} while (mechs > 0 && !present);

	gss_release_oid_set(&ms, &supported);

	if (!present) {
		xfree(doid);
		return (0);
	}

	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid))))
		return (0);

	authctxt->methoddata=(void *)ctxt;

	packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);

	/* Return OID in same format as we received it*/
	packet_put_string(doid, len);

	packet_send();
	xfree(doid);

	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
	authctxt->postponed = 1;

	return (0);
}

static void
input_gssapi_token(int type, u_int32_t plen, void *ctxt)
{
	Authctxt *authctxt = ctxt;
	Gssctxt *gssctxt;
	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	gss_buffer_desc recv_tok;
	OM_uint32 maj_status, min_status;
	u_int len;

	if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
		fatal("No authentication or GSSAPI context");

	gssctxt = authctxt->methoddata;
	recv_tok.value = packet_get_string(&len);
	recv_tok.length = len; /* u_int vs. size_t */

	packet_check_eom();

	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
	    &send_tok, NULL));

	xfree(recv_tok.value);

	if (GSS_ERROR(maj_status)) {
		if (send_tok.length != 0) {
			packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
			packet_put_string(send_tok.value, send_tok.length);
			packet_send();
		}
		authctxt->postponed = 0;
		dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
		userauth_finish(authctxt, 0, "gssapi");
	} else {
		if (send_tok.length != 0) {
			packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
			packet_put_string(send_tok.value, send_tok.length);
			packet_send();
		}
		if (maj_status == GSS_S_COMPLETE) {
			dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
			dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
				     &input_gssapi_exchange_complete);
		}
	}

	gss_release_buffer(&min_status, &send_tok);
}

static void
input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
{
	Authctxt *authctxt = ctxt;
	Gssctxt *gssctxt;
	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	gss_buffer_desc recv_tok;
	OM_uint32 maj_status;

	if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
		fatal("No authentication or GSSAPI context");

	gssctxt = authctxt->methoddata;
	recv_tok.value = packet_get_string(&recv_tok.length);

	packet_check_eom();

	/* Push the error token into GSSAPI to see what it says */
	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
	    &send_tok, NULL));

	xfree(recv_tok.value);

	/* We can't return anything to the client, even if we wanted to */
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);

	/* The client will have already moved on to the next auth */

	gss_release_buffer(&maj_status, &send_tok);
}

/*
 * This is called when the client thinks we've completed authentication.
 * It should only be enabled in the dispatch handler by the function above,
 * which only enables it once the GSSAPI exchange is complete.
 */

static void
input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
{
	Authctxt *authctxt = ctxt;
	Gssctxt *gssctxt;
	int authenticated;

	if (authctxt == NULL || (authctxt->methoddata == NULL && !use_privsep))
		fatal("No authentication or GSSAPI context");

	gssctxt = authctxt->methoddata;

	/*
	 * We don't need to check the status, because the stored credentials
	 * which userok uses are only populated once the context init step
	 * has returned complete.
	 */

	packet_check_eom();

	authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));

	authctxt->postponed = 0;
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
	userauth_finish(authctxt, authenticated, "gssapi");
}

Authmethod method_gssapi = {
	"gssapi",
	userauth_gssapi,
	&options.gss_authentication
};

#endif /* GSSAPI */
Commit	Line	Data
7364bd04	1	/* $OpenBSD: auth2-gss.c,v 1.1 2003/08/22 10:56:08 markus Exp $ */
	2
	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
	43	extern ServerOptions options;
	44
	45	static void input_gssapi_token(int type, u_int32_t plen, void *ctxt);
	46	static void input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt);
	47	static 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	*/
	53	static int
	54	userauth_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
101	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &oid))))
102	return (0);
103
104	authctxt->methoddata=(void *)ctxt;
105
106	packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
107
108	/* Return OID in same format as we received it*/
109	packet_put_string(doid, len);
110
111	packet_send();
112	xfree(doid);
113
114	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
115	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
116	authctxt->postponed = 1;
117
118	return (0);
119	}
120
121	static void
122	input_gssapi_token(int type, u_int32_t plen, void *ctxt)
123	{
124	Authctxt *authctxt = ctxt;
125	Gssctxt *gssctxt;
126	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
127	gss_buffer_desc recv_tok;
128	OM_uint32 maj_status, min_status;
129	u_int len;
130
131	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
132	fatal("No authentication or GSSAPI context");
133
134	gssctxt = authctxt->methoddata;
135	recv_tok.value = packet_get_string(&len);
136	recv_tok.length = len; /* u_int vs. size_t */
137
138	packet_check_eom();
139
140	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
141	&send_tok, NULL));
142
143	xfree(recv_tok.value);
144
145	if (GSS_ERROR(maj_status)) {
146	if (send_tok.length != 0) {
147	packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
148	packet_put_string(send_tok.value, send_tok.length);
149	packet_send();
150	}
151	authctxt->postponed = 0;
152	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
153	userauth_finish(authctxt, 0, "gssapi");
154	} else {
155	if (send_tok.length != 0) {
156	packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
157	packet_put_string(send_tok.value, send_tok.length);
158	packet_send();
159	}
160	if (maj_status == GSS_S_COMPLETE) {
161	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
162	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
163	&input_gssapi_exchange_complete);
164	}
165	}
166
167	gss_release_buffer(&min_status, &send_tok);
168	}
169
170	static void
171	input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
172	{
173	Authctxt *authctxt = ctxt;
174	Gssctxt *gssctxt;
175	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
176	gss_buffer_desc recv_tok;
177	OM_uint32 maj_status;
178
179	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
180	fatal("No authentication or GSSAPI context");
181
182	gssctxt = authctxt->methoddata;
183	recv_tok.value = packet_get_string(&recv_tok.length);
184
185	packet_check_eom();
186
187	/* Push the error token into GSSAPI to see what it says */
188	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
189	&send_tok, NULL));
190
191	xfree(recv_tok.value);
192
193	/* We can't return anything to the client, even if we wanted to */
194	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
195	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
196
197	/* The client will have already moved on to the next auth */
198
199	gss_release_buffer(&maj_status, &send_tok);
200	}
201
202	/*
203	* This is called when the client thinks we've completed authentication.
204	* It should only be enabled in the dispatch handler by the function above,
205	* which only enables it once the GSSAPI exchange is complete.
206	*/
207
208	static void
209	input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
210	{
211	Authctxt *authctxt = ctxt;
212	Gssctxt *gssctxt;
213	int authenticated;
214
215	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
216	fatal("No authentication or GSSAPI context");
217
218	gssctxt = authctxt->methoddata;
219
220	/*
221	* We don't need to check the status, because the stored credentials
222	* which userok uses are only populated once the context init step
223	* has returned complete.
224	*/
225
226	packet_check_eom();
227
228	authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
229
230	authctxt->postponed = 0;
231	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
232	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
233	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
234	userauth_finish(authctxt, authenticated, "gssapi");
235	}
236
237	Authmethod method_gssapi = {
238	"gssapi",
239	userauth_gssapi,
240	&options.gss_authentication
241	};
242
243	#endif /* GSSAPI */