[gssapi-openssh.git] / openssh / kexgssc.c

/*
 * Copyright (c) 2001-2009 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 "includes.h"

#include <openssl/crypto.h>
#include <openssl/bn.h>

#include <string.h>

#include "xmalloc.h"
#include "buffer.h"
#include "ssh2.h"
#include "key.h"
#include "cipher.h"
#include "kex.h"
#include "log.h"
#include "packet.h"
#include "dh.h"

#include "ssh-gss.h"

void
kexgss_client(Kex *kex) {
	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	gss_buffer_desc recv_tok, gssbuf, msg_tok, *token_ptr;
	Gssctxt *ctxt;
	OM_uint32 maj_status, min_status, ret_flags;
	u_int klen, kout, slen = 0, hashlen, strlen;
	DH *dh; 
	BIGNUM *dh_server_pub = NULL;
	BIGNUM *shared_secret = NULL;
	BIGNUM *p = NULL;
	BIGNUM *g = NULL;	
	u_char *kbuf, *hash;
	u_char *serverhostkey = NULL;
	u_char *empty = "";
	char *msg;
	char *lang;
	int type = 0;
	int first = 1;
	int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX;

	/* Initialise our GSSAPI world */	
	ssh_gssapi_build_ctx(&ctxt);
	if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type) 
	    == GSS_C_NO_OID)
		fatal("Couldn't identify host exchange");

	if (ssh_gssapi_import_name(ctxt, kex->gss_host))
		fatal("Couldn't import hostname");

	if (kex->gss_client && 
	    ssh_gssapi_client_identity(ctxt, kex->gss_client))
		fatal("Couldn't acquire client credentials");

	switch (kex->kex_type) {
	case KEX_GSS_GRP1_SHA1:
		dh = dh_new_group1();
		break;
	case KEX_GSS_GRP14_SHA1:
		dh = dh_new_group14();
		break;
	case KEX_GSS_GEX_SHA1:
		debug("Doing group exchange\n");
		nbits = dh_estimate(kex->we_need * 8);
		packet_start(SSH2_MSG_KEXGSS_GROUPREQ);
		packet_put_int(min);
		packet_put_int(nbits);
		packet_put_int(max);

		packet_send();

		packet_read_expect(SSH2_MSG_KEXGSS_GROUP);

		if ((p = BN_new()) == NULL)
			fatal("BN_new() failed");
		packet_get_bignum2(p);
		if ((g = BN_new()) == NULL)
			fatal("BN_new() failed");
		packet_get_bignum2(g);
		packet_check_eom();

		if (BN_num_bits(p) < min || BN_num_bits(p) > max)
			fatal("GSSGRP_GEX group out of range: %d !< %d !< %d",
			    min, BN_num_bits(p), max);

		dh = dh_new_group(g, p);
		break;
	default:
		fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
	}
	
	/* Step 1 - e is dh->pub_key */
	dh_gen_key(dh, kex->we_need * 8);

	/* This is f, we initialise it now to make life easier */
	dh_server_pub = BN_new();
	if (dh_server_pub == NULL)
		fatal("dh_server_pub == NULL");

	token_ptr = GSS_C_NO_BUFFER;
			 
	do {
		debug("Calling gss_init_sec_context");
		
		maj_status = ssh_gssapi_init_ctx(ctxt,
		    kex->gss_deleg_creds, token_ptr, &send_tok,
		    &ret_flags);

		if (GSS_ERROR(maj_status)) {
			if (send_tok.length != 0) {
				packet_start(SSH2_MSG_KEXGSS_CONTINUE);
				packet_put_string(send_tok.value,
				    send_tok.length);
			}
			fatal("gss_init_context failed");
		}

		/* If we've got an old receive buffer get rid of it */
		if (token_ptr != GSS_C_NO_BUFFER)
			xfree(recv_tok.value);

		if (maj_status == GSS_S_COMPLETE) {
			/* If mutual state flag is not true, kex fails */
			if (!(ret_flags & GSS_C_MUTUAL_FLAG))
				fatal("Mutual authentication failed");

			/* If integ avail flag is not true kex fails */
			if (!(ret_flags & GSS_C_INTEG_FLAG))
				fatal("Integrity check failed");
		}

		/* 
		 * If we have data to send, then the last message that we
		 * received cannot have been a 'complete'. 
		 */
		if (send_tok.length != 0) {
			if (first) {
				packet_start(SSH2_MSG_KEXGSS_INIT);
				packet_put_string(send_tok.value,
				    send_tok.length);
				packet_put_bignum2(dh->pub_key);
				first = 0;
			} else {
				packet_start(SSH2_MSG_KEXGSS_CONTINUE);
				packet_put_string(send_tok.value,
				    send_tok.length);
			}
			packet_send();
			gss_release_buffer(&min_status, &send_tok);

			/* If we've sent them data, they should reply */
			do {	
				type = packet_read();
				if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
					debug("Received KEXGSS_HOSTKEY");
					if (serverhostkey)
						fatal("Server host key received more than once");
					serverhostkey = 
					    packet_get_string(&slen);
				}
			} while (type == SSH2_MSG_KEXGSS_HOSTKEY);

			switch (type) {
			case SSH2_MSG_KEXGSS_CONTINUE:
				debug("Received GSSAPI_CONTINUE");
				if (maj_status == GSS_S_COMPLETE) 
					fatal("GSSAPI Continue received from server when complete");
				recv_tok.value = packet_get_string(&strlen);
				recv_tok.length = strlen; 
				break;
			case SSH2_MSG_KEXGSS_COMPLETE:
				debug("Received GSSAPI_COMPLETE");
				packet_get_bignum2(dh_server_pub);
				msg_tok.value =  packet_get_string(&strlen);
				msg_tok.length = strlen; 

				/* Is there a token included? */
				if (packet_get_char()) {
					recv_tok.value=
					    packet_get_string(&strlen);
					recv_tok.length = strlen;
					/* If we're already complete - protocol error */
					if (maj_status == GSS_S_COMPLETE)
						packet_disconnect("Protocol error: received token when complete");
					} else {
						/* No token included */
						if (maj_status != GSS_S_COMPLETE)
							packet_disconnect("Protocol error: did not receive final token");
				}
				break;
			case SSH2_MSG_KEXGSS_ERROR:
				debug("Received Error");
				maj_status = packet_get_int();
				min_status = packet_get_int();
				msg = packet_get_string(NULL);
				lang = packet_get_string(NULL);
				fatal("GSSAPI Error: \n%.400s",msg);
			default:
				packet_disconnect("Protocol error: didn't expect packet type %d",
		    		type);
			}
			token_ptr = &recv_tok;
		} else {
			/* No data, and not complete */
			if (maj_status != GSS_S_COMPLETE)
				fatal("Not complete, and no token output");
		}
	} while (maj_status & GSS_S_CONTINUE_NEEDED);

	/* 
	 * We _must_ have received a COMPLETE message in reply from the 
	 * server, which will have set dh_server_pub and msg_tok 
	 */

	if (type != SSH2_MSG_KEXGSS_COMPLETE)
		fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");

	/* Check f in range [1, p-1] */
	if (!dh_pub_is_valid(dh, dh_server_pub))
		packet_disconnect("bad server public DH value");

	/* compute K=f^x mod p */
	klen = DH_size(dh);
	kbuf = xmalloc(klen);
	kout = DH_compute_key(kbuf, dh_server_pub, dh);
	if (kout < 0)
		fatal("DH_compute_key: failed");

	shared_secret = BN_new();
	if (shared_secret == NULL)
		fatal("kexgss_client: BN_new failed");

	if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
		fatal("kexdh_client: BN_bin2bn failed");

	memset(kbuf, 0, klen);
	xfree(kbuf);

	switch (kex->kex_type) {
	case KEX_GSS_GRP1_SHA1:
	case KEX_GSS_GRP14_SHA1:
		kex_dh_hash( kex->client_version_string, 
		    kex->server_version_string,
		    buffer_ptr(&kex->my), buffer_len(&kex->my),
		    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
		    (serverhostkey ? serverhostkey : empty), slen,
		    dh->pub_key,	/* e */
		    dh_server_pub,	/* f */
		    shared_secret,	/* K */
		    &hash, &hashlen
		);
		break;
	case KEX_GSS_GEX_SHA1:
		kexgex_hash(
		    kex->evp_md,
		    kex->client_version_string,
		    kex->server_version_string,
		    buffer_ptr(&kex->my), buffer_len(&kex->my),
		    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
		    (serverhostkey ? serverhostkey : empty), slen,
 		    min, nbits, max,
		    dh->p, dh->g,
		    dh->pub_key,
		    dh_server_pub,
		    shared_secret,
		    &hash, &hashlen
		);
		break;
	default:
		fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
	}

	gssbuf.value = hash;
	gssbuf.length = hashlen;

	/* Verify that the hash matches the MIC we just got. */
	if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok)))
		packet_disconnect("Hash's MIC didn't verify");

	xfree(msg_tok.value);

	DH_free(dh);
	if (serverhostkey)
		xfree(serverhostkey);
	BN_clear_free(dh_server_pub);

	/* save session id */
	if (kex->session_id == NULL) {
		kex->session_id_len = hashlen;
		kex->session_id = xmalloc(kex->session_id_len);
		memcpy(kex->session_id, hash, kex->session_id_len);
	}

	if (kex->gss_deleg_creds)
		ssh_gssapi_credentials_updated(ctxt);

	if (gss_kex_context == NULL)
		gss_kex_context = ctxt;
	else
		ssh_gssapi_delete_ctx(&ctxt);

	kex_derive_keys(kex, hash, hashlen, shared_secret);
	BN_clear_free(shared_secret);
	kex_finish(kex);
}

#endif /* GSSAPI */
Commit	Line	Data
f97edba6	1	/*
	2	* Copyright (c) 2001-2009 Simon Wilkinson. All rights reserved.
	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
	12	*
	13	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	15	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	16	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	17	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	18	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	19	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	20	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	21	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	22	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	23	*/
	24
	25	#include "includes.h"
	26
	27	#ifdef GSSAPI
	28
	29	#include "includes.h"
	30
	31	#include <openssl/crypto.h>
	32	#include <openssl/bn.h>
	33
	34	#include <string.h>
	35
	36	#include "xmalloc.h"
	37	#include "buffer.h"
	38	#include "ssh2.h"
	39	#include "key.h"
	40	#include "cipher.h"
	41	#include "kex.h"
	42	#include "log.h"
	43	#include "packet.h"
	44	#include "dh.h"
	45
	46	#include "ssh-gss.h"
	47
	48	void
	49	kexgss_client(Kex *kex) {
	50	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	51	gss_buffer_desc recv_tok, gssbuf, msg_tok, *token_ptr;
	52	Gssctxt *ctxt;
	53	OM_uint32 maj_status, min_status, ret_flags;
	54	u_int klen, kout, slen = 0, hashlen, strlen;
	55	DH *dh;
	56	BIGNUM *dh_server_pub = NULL;
	57	BIGNUM *shared_secret = NULL;
	58	BIGNUM *p = NULL;
	59	BIGNUM *g = NULL;
	60	u_char kbuf, hash;
	61	u_char *serverhostkey = NULL;
	62	u_char *empty = "";
	63	char *msg;
	64	char *lang;
65	int type = 0;
66	int first = 1;
67	int nbits = 0, min = DH_GRP_MIN, max = DH_GRP_MAX;
68
69	/* Initialise our GSSAPI world */
70	ssh_gssapi_build_ctx(&ctxt);
71	if (ssh_gssapi_id_kex(ctxt, kex->name, kex->kex_type)
72	== GSS_C_NO_OID)
73	fatal("Couldn't identify host exchange");
74
75	if (ssh_gssapi_import_name(ctxt, kex->gss_host))
76	fatal("Couldn't import hostname");
77
78	if (kex->gss_client &&
79	ssh_gssapi_client_identity(ctxt, kex->gss_client))
80	fatal("Couldn't acquire client credentials");
81
82	switch (kex->kex_type) {
83	case KEX_GSS_GRP1_SHA1:
84	dh = dh_new_group1();
85	break;
86	case KEX_GSS_GRP14_SHA1:
87	dh = dh_new_group14();
88	break;
89	case KEX_GSS_GEX_SHA1:
90	debug("Doing group exchange\n");
91	nbits = dh_estimate(kex->we_need * 8);
92	packet_start(SSH2_MSG_KEXGSS_GROUPREQ);
93	packet_put_int(min);
94	packet_put_int(nbits);
95	packet_put_int(max);
96
97	packet_send();
98
99	packet_read_expect(SSH2_MSG_KEXGSS_GROUP);
100
101	if ((p = BN_new()) == NULL)
102	fatal("BN_new() failed");
103	packet_get_bignum2(p);
104	if ((g = BN_new()) == NULL)
105	fatal("BN_new() failed");
106	packet_get_bignum2(g);
107	packet_check_eom();
108
109	if (BN_num_bits(p) < min \|\| BN_num_bits(p) > max)
110	fatal("GSSGRP_GEX group out of range: %d !< %d !< %d",
111	min, BN_num_bits(p), max);
112
113	dh = dh_new_group(g, p);
114	break;
115	default:
116	fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
117	}
118
119	/* Step 1 - e is dh->pub_key */
120	dh_gen_key(dh, kex->we_need * 8);
121
122	/* This is f, we initialise it now to make life easier */
123	dh_server_pub = BN_new();
124	if (dh_server_pub == NULL)
125	fatal("dh_server_pub == NULL");
126
127	token_ptr = GSS_C_NO_BUFFER;
128
129	do {
130	debug("Calling gss_init_sec_context");
131
132	maj_status = ssh_gssapi_init_ctx(ctxt,
133	kex->gss_deleg_creds, token_ptr, &send_tok,
134	&ret_flags);
135
136	if (GSS_ERROR(maj_status)) {
137	if (send_tok.length != 0) {
138	packet_start(SSH2_MSG_KEXGSS_CONTINUE);
139	packet_put_string(send_tok.value,
140	send_tok.length);
141	}
142	fatal("gss_init_context failed");
143	}
144
145	/* If we've got an old receive buffer get rid of it */
146	if (token_ptr != GSS_C_NO_BUFFER)
147	xfree(recv_tok.value);
148
149	if (maj_status == GSS_S_COMPLETE) {
150	/* If mutual state flag is not true, kex fails */
151	if (!(ret_flags & GSS_C_MUTUAL_FLAG))
152	fatal("Mutual authentication failed");
153
154	/* If integ avail flag is not true kex fails */
155	if (!(ret_flags & GSS_C_INTEG_FLAG))
156	fatal("Integrity check failed");
157	}
158
159	/*
160	* If we have data to send, then the last message that we
161	* received cannot have been a 'complete'.
162	*/
163	if (send_tok.length != 0) {
164	if (first) {
165	packet_start(SSH2_MSG_KEXGSS_INIT);
166	packet_put_string(send_tok.value,
167	send_tok.length);
168	packet_put_bignum2(dh->pub_key);
169	first = 0;
170	} else {
171	packet_start(SSH2_MSG_KEXGSS_CONTINUE);
172	packet_put_string(send_tok.value,
173	send_tok.length);
174	}
175	packet_send();
176	gss_release_buffer(&min_status, &send_tok);
177
178	/* If we've sent them data, they should reply */
179	do {
180	type = packet_read();
181	if (type == SSH2_MSG_KEXGSS_HOSTKEY) {
182	debug("Received KEXGSS_HOSTKEY");
183	if (serverhostkey)
184	fatal("Server host key received more than once");
185	serverhostkey =
186	packet_get_string(&slen);
187	}
188	} while (type == SSH2_MSG_KEXGSS_HOSTKEY);
189
190	switch (type) {
191	case SSH2_MSG_KEXGSS_CONTINUE:
192	debug("Received GSSAPI_CONTINUE");
193	if (maj_status == GSS_S_COMPLETE)
194	fatal("GSSAPI Continue received from server when complete");
195	recv_tok.value = packet_get_string(&strlen);
196	recv_tok.length = strlen;
197	break;
198	case SSH2_MSG_KEXGSS_COMPLETE:
199	debug("Received GSSAPI_COMPLETE");
200	packet_get_bignum2(dh_server_pub);
201	msg_tok.value = packet_get_string(&strlen);
202	msg_tok.length = strlen;
203
204	/* Is there a token included? */
205	if (packet_get_char()) {
206	recv_tok.value=
207	packet_get_string(&strlen);
208	recv_tok.length = strlen;
209	/* If we're already complete - protocol error */
210	if (maj_status == GSS_S_COMPLETE)
211	packet_disconnect("Protocol error: received token when complete");
212	} else {
213	/* No token included */
214	if (maj_status != GSS_S_COMPLETE)
215	packet_disconnect("Protocol error: did not receive final token");
216	}
217	break;
218	case SSH2_MSG_KEXGSS_ERROR:
219	debug("Received Error");
220	maj_status = packet_get_int();
221	min_status = packet_get_int();
222	msg = packet_get_string(NULL);
223	lang = packet_get_string(NULL);
224	fatal("GSSAPI Error: \n%.400s",msg);
225	default:
226	packet_disconnect("Protocol error: didn't expect packet type %d",
227	type);
228	}
229	token_ptr = &recv_tok;
230	} else {
231	/* No data, and not complete */
232	if (maj_status != GSS_S_COMPLETE)
233	fatal("Not complete, and no token output");
234	}
235	} while (maj_status & GSS_S_CONTINUE_NEEDED);
236
237	/*
238	* We _must_ have received a COMPLETE message in reply from the
239	* server, which will have set dh_server_pub and msg_tok
240	*/
241
242	if (type != SSH2_MSG_KEXGSS_COMPLETE)
243	fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");
244
245	/* Check f in range [1, p-1] */
246	if (!dh_pub_is_valid(dh, dh_server_pub))
247	packet_disconnect("bad server public DH value");
248
249	/* compute K=f^x mod p */
250	klen = DH_size(dh);
251	kbuf = xmalloc(klen);
252	kout = DH_compute_key(kbuf, dh_server_pub, dh);
253	if (kout < 0)
254	fatal("DH_compute_key: failed");
255
256	shared_secret = BN_new();
257	if (shared_secret == NULL)
258	fatal("kexgss_client: BN_new failed");
259
260	if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
261	fatal("kexdh_client: BN_bin2bn failed");
262
263	memset(kbuf, 0, klen);
264	xfree(kbuf);
265
266	switch (kex->kex_type) {
267	case KEX_GSS_GRP1_SHA1:
268	case KEX_GSS_GRP14_SHA1:
269	kex_dh_hash( kex->client_version_string,
270	kex->server_version_string,
271	buffer_ptr(&kex->my), buffer_len(&kex->my),
272	buffer_ptr(&kex->peer), buffer_len(&kex->peer),
273	(serverhostkey ? serverhostkey : empty), slen,
274	dh->pub_key, /* e */
275	dh_server_pub, /* f */
276	shared_secret, /* K */
277	&hash, &hashlen
278	);
279	break;
280	case KEX_GSS_GEX_SHA1:
281	kexgex_hash(
282	kex->evp_md,
283	kex->client_version_string,
284	kex->server_version_string,
285	buffer_ptr(&kex->my), buffer_len(&kex->my),
286	buffer_ptr(&kex->peer), buffer_len(&kex->peer),
287	(serverhostkey ? serverhostkey : empty), slen,
288	min, nbits, max,
289	dh->p, dh->g,
290	dh->pub_key,
291	dh_server_pub,
292	shared_secret,
293	&hash, &hashlen
294	);
295	break;
296	default:
297	fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
298	}
299
300	gssbuf.value = hash;
301	gssbuf.length = hashlen;
302
303	/* Verify that the hash matches the MIC we just got. */
304	if (GSS_ERROR(ssh_gssapi_checkmic(ctxt, &gssbuf, &msg_tok)))
305	packet_disconnect("Hash's MIC didn't verify");
306
307	xfree(msg_tok.value);
308
309	DH_free(dh);
310	if (serverhostkey)
311	xfree(serverhostkey);
312	BN_clear_free(dh_server_pub);
313
314	/* save session id */
315	if (kex->session_id == NULL) {
316	kex->session_id_len = hashlen;
317	kex->session_id = xmalloc(kex->session_id_len);
318	memcpy(kex->session_id, hash, kex->session_id_len);
319	}
320
321	if (kex->gss_deleg_creds)
322	ssh_gssapi_credentials_updated(ctxt);
323
324	if (gss_kex_context == NULL)
325	gss_kex_context = ctxt;
326	else
327	ssh_gssapi_delete_ctx(&ctxt);
328
329	kex_derive_keys(kex, hash, hashlen, shared_secret);
330	BN_clear_free(shared_secret);
331	kex_finish(kex);
332	}
333
334	#endif /* GSSAPI */