[openssh.git] / auth2-gss.c

/*	$OpenBSD: auth2-gss.c,v 1.10 2005/07/17 07:17:54 djm 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_mic(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 goid = {0, NULL};
	Gssctxt *ctxt = NULL;
	int mechs;
	gss_OID_set supported;
	int present;
	OM_uint32 ms;
	u_int len;
	u_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);

		present = 0;
		doid = packet_get_string(&len);

		if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
		    doid[1] == len - 2) {
			goid.elements = doid + 2;
			goid.length   = len - 2;
			gss_test_oid_set_member(&ms, &goid, supported,
			    &present);
		} else {
			logit("Badly formed OID received");
		}
	} 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, &goid)))) {
		xfree(doid);
		return (0);
	}

	authctxt->methoddata=(void *)ctxt;

	packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);

	/* Return the OID that we received */
	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, flags;
	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, &flags));

	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-with-mic");
	} 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);
			if (flags & GSS_C_INTEG_FLAG)
				dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC,
				    &input_gssapi_mic);
			else
				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;
	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;

	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 we're only enabled in
	 * the dispatcher once the exchange is 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_MIC, NULL);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
	userauth_finish(authctxt, authenticated, "gssapi-with-mic");
}

static void
input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
{
	Authctxt *authctxt = ctxt;
	Gssctxt *gssctxt;
	int authenticated = 0;
	Buffer b;
	gss_buffer_desc mic, gssbuf;
	u_int len;

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

	gssctxt = authctxt->methoddata;

	mic.value = packet_get_string(&len);
	mic.length = len;

	ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
	    "gssapi-with-mic");

	gssbuf.value = buffer_ptr(&b);
	gssbuf.length = buffer_len(&b);

	if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
		authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
	else
		logit("GSSAPI MIC check failed");

	buffer_free(&b);
	xfree(mic.value);

	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_MIC, NULL);
	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
	userauth_finish(authctxt, authenticated, "gssapi-with-mic");
}

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

#endif /* GSSAPI */
Commit	Line	Data
4e2e5cfd	1	/* $OpenBSD: auth2-gss.c,v 1.10 2005/07/17 07:17:54 djm Exp $ */
7364bd04	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);
0789992b	46	static void input_gssapi_mic(int type, u_int32_t plen, void *ctxt);
7364bd04	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 *);
	49
	50	/*
	51	* We only support those mechanisms that we know about (ie ones that we know
	52	* how to check local user kuserok and the like
	53	*/
	54	static int
	55	userauth_gssapi(Authctxt *authctxt)
	56	{
ca75d7de	57	gss_OID_desc goid = {0, NULL};
7364bd04	58	Gssctxt *ctxt = NULL;
	59	int mechs;
	60	gss_OID_set supported;
	61	int present;
	62	OM_uint32 ms;
	63	u_int len;
2ceb8101	64	u_char *doid = NULL;
7364bd04	65
	66	if (!authctxt->valid \|\| authctxt->user == NULL)
	67	return (0);
	68
	69	mechs = packet_get_int();
	70	if (mechs == 0) {
	71	debug("Mechanism negotiation is not supported");
	72	return (0);
	73	}
	74
	75	ssh_gssapi_supported_oids(&supported);
	76	do {
	77	mechs--;
	78
	79	if (doid)
	80	xfree(doid);
	81
d8d9afd0	82	present = 0;
7364bd04	83	doid = packet_get_string(&len);
7364bd04	84
4e2e5cfd	85	if (len > 2 && doid[0] == SSH_GSS_OIDTYPE &&
4e2e5cfd	86	doid[1] == len - 2) {
ca75d7de	87	goid.elements = doid + 2;
	88	goid.length = len - 2;
	89	gss_test_oid_set_member(&ms, &goid, supported,
d8d9afd0	90	&present);
7364bd04	91	} else {
d8d9afd0	92	logit("Badly formed OID received");
7364bd04	93	}
7364bd04	94	} while (mechs > 0 && !present);
	95
	96	gss_release_oid_set(&ms, &supported);
	97
	98	if (!present) {
	99	xfree(doid);
	100	return (0);
	101	}
	102
ca75d7de	103	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, &goid)))) {
4771605b	104	xfree(doid);
7364bd04	105	return (0);
4771605b	106	}
7364bd04	107
	108	authctxt->methoddata=(void *)ctxt;
	109
	110	packet_start(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE);
	111
d8d9afd0	112	/* Return the OID that we received */
7364bd04	113	packet_put_string(doid, len);
	114
	115	packet_send();
	116	xfree(doid);
	117
	118	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
	119	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
	120	authctxt->postponed = 1;
	121
	122	return (0);
	123	}
	124
	125	static void
	126	input_gssapi_token(int type, u_int32_t plen, void *ctxt)
	127	{
	128	Authctxt *authctxt = ctxt;
	129	Gssctxt *gssctxt;
	130	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	131	gss_buffer_desc recv_tok;
0789992b	132	OM_uint32 maj_status, min_status, flags;
7364bd04	133	u_int len;
	134
	135	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
	136	fatal("No authentication or GSSAPI context");
	137
	138	gssctxt = authctxt->methoddata;
	139	recv_tok.value = packet_get_string(&len);
	140	recv_tok.length = len; /* u_int vs. size_t */
	141
	142	packet_check_eom();
	143
	144	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
0789992b	145	&send_tok, &flags));
7364bd04	146
	147	xfree(recv_tok.value);
	148
	149	if (GSS_ERROR(maj_status)) {
	150	if (send_tok.length != 0) {
	151	packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
	152	packet_put_string(send_tok.value, send_tok.length);
	153	packet_send();
	154	}
	155	authctxt->postponed = 0;
	156	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
0789992b	157	userauth_finish(authctxt, 0, "gssapi-with-mic");
7364bd04	158	} else {
	159	if (send_tok.length != 0) {
	160	packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
	161	packet_put_string(send_tok.value, send_tok.length);
	162	packet_send();
	163	}
	164	if (maj_status == GSS_S_COMPLETE) {
	165	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
0789992b	166	if (flags & GSS_C_INTEG_FLAG)
	167	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC,
	168	&input_gssapi_mic);
	169	else
	170	dispatch_set(
	171	SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE,
	172	&input_gssapi_exchange_complete);
7364bd04	173	}
	174	}
	175
	176	gss_release_buffer(&min_status, &send_tok);
	177	}
	178
	179	static void
	180	input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
	181	{
	182	Authctxt *authctxt = ctxt;
	183	Gssctxt *gssctxt;
	184	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	185	gss_buffer_desc recv_tok;
	186	OM_uint32 maj_status;
eb18f58d	187	u_int len;
7364bd04	188
	189	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
	190	fatal("No authentication or GSSAPI context");
	191
	192	gssctxt = authctxt->methoddata;
eb18f58d	193	recv_tok.value = packet_get_string(&len);
eb18f58d	194	recv_tok.length = len;
7364bd04	195
	196	packet_check_eom();
	197
	198	/* Push the error token into GSSAPI to see what it says */
	199	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(gssctxt, &recv_tok,
	200	&send_tok, NULL));
	201
	202	xfree(recv_tok.value);
	203
	204	/* We can't return anything to the client, even if we wanted to */
	205	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	206	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
	207
	208	/* The client will have already moved on to the next auth */
	209
	210	gss_release_buffer(&maj_status, &send_tok);
	211	}
	212
	213	/*
	214	* This is called when the client thinks we've completed authentication.
	215	* It should only be enabled in the dispatch handler by the function above,
	216	* which only enables it once the GSSAPI exchange is complete.
	217	*/
	218
	219	static void
	220	input_gssapi_exchange_complete(int type, u_int32_t plen, void *ctxt)
	221	{
	222	Authctxt *authctxt = ctxt;
	223	Gssctxt *gssctxt;
	224	int authenticated;
	225
	226	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
	227	fatal("No authentication or GSSAPI context");
	228
	229	gssctxt = authctxt->methoddata;
	230
	231	/*
0789992b	232	* We don't need to check the status, because we're only enabled in
0789992b	233	* the dispatcher once the exchange is complete
7364bd04	234	*/
	235
	236	packet_check_eom();
	237
	238	authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
	239
	240	authctxt->postponed = 0;
	241	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	242	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
0789992b	243	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
	244	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
	245	userauth_finish(authctxt, authenticated, "gssapi-with-mic");
	246	}
	247
	248	static void
	249	input_gssapi_mic(int type, u_int32_t plen, void *ctxt)
	250	{
	251	Authctxt *authctxt = ctxt;
	252	Gssctxt *gssctxt;
	253	int authenticated = 0;
	254	Buffer b;
	255	gss_buffer_desc mic, gssbuf;
	256	u_int len;
b6453d99	257
0789992b	258	if (authctxt == NULL \|\| (authctxt->methoddata == NULL && !use_privsep))
0789992b	259	fatal("No authentication or GSSAPI context");
b6453d99	260
0789992b	261	gssctxt = authctxt->methoddata;
b6453d99	262
0789992b	263	mic.value = packet_get_string(&len);
0789992b	264	mic.length = len;
b6453d99	265
0789992b	266	ssh_gssapi_buildmic(&b, authctxt->user, authctxt->service,
0789992b	267	"gssapi-with-mic");
b6453d99	268
0789992b	269	gssbuf.value = buffer_ptr(&b);
0789992b	270	gssbuf.length = buffer_len(&b);
b6453d99	271
0789992b	272	if (!GSS_ERROR(PRIVSEP(ssh_gssapi_checkmic(gssctxt, &gssbuf, &mic))))
	273	authenticated = PRIVSEP(ssh_gssapi_userok(authctxt->user));
	274	else
	275	logit("GSSAPI MIC check failed");
	276
	277	buffer_free(&b);
	278	xfree(mic.value);
b6453d99	279
0789992b	280	authctxt->postponed = 0;
	281	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
	282	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, NULL);
	283	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_MIC, NULL);
7364bd04	284	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
0789992b	285	userauth_finish(authctxt, authenticated, "gssapi-with-mic");
7364bd04	286	}
	287
	288	Authmethod method_gssapi = {
0789992b	289	"gssapi-with-mic",
7364bd04	290	userauth_gssapi,
	291	&options.gss_authentication
	292	};
	293
	294	#endif /* GSSAPI */