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

/*
 * Copyright (c) 2001-2006 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 <string.h>

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

void
kexgss_server(Kex *kex)
{
	OM_uint32 maj_status, min_status;
	
	/* 
	 * Some GSSAPI implementations use the input value of ret_flags (an
 	 * output variable) as a means of triggering mechanism specific 
 	 * features. Initializing it to zero avoids inadvertently 
 	 * activating this non-standard behaviour.
	 */

	OM_uint32 ret_flags = 0;
	gss_buffer_desc gssbuf, recv_tok, msg_tok;
	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	Gssctxt *ctxt = NULL;
	u_int slen, klen, kout, hashlen;
	u_char *kbuf, *hash;
	DH *dh;
	int min = -1, max = -1, nbits = -1;
	BIGNUM *shared_secret = NULL;
	BIGNUM *dh_client_pub = NULL;
	int type = 0;
	gss_OID oid;

	/* Initialise GSSAPI */

	/* If we're rekeying, privsep means that some of the private structures
	 * in the GSSAPI code are no longer available. This kludges them back
	 * into life
	 */
	if (!ssh_gssapi_oid_table_ok()) 
		ssh_gssapi_server_mechanisms();

	debug2("%s: Identifying %s", __func__, kex->name);
	oid = ssh_gssapi_id_kex(NULL, kex->name, kex->kex_type);
	if (oid == GSS_C_NO_OID)
	   fatal("Unknown gssapi mechanism");

	debug2("%s: Acquiring credentials", __func__);

	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, oid))))
		fatal("Unable to acquire credentials for the server");

	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");
		packet_read_expect(SSH2_MSG_KEXGSS_GROUPREQ);
		min = packet_get_int();
		nbits = packet_get_int();
		max = packet_get_int();
		min = MAX(DH_GRP_MIN, min);
		max = MIN(DH_GRP_MAX, max);
		packet_check_eom();
		if (max < min || nbits < min || max < nbits)
			fatal("GSS_GEX, bad parameters: %d !< %d !< %d",
			    min, nbits, max);
		dh = PRIVSEP(choose_dh(min, nbits, max));
		if (dh == NULL)
			packet_disconnect("Protocol error: no matching group found");

		packet_start(SSH2_MSG_KEXGSS_GROUP);
		packet_put_bignum2(dh->p);
		packet_put_bignum2(dh->g);
		packet_send();

		packet_write_wait();
		break;
	default:
		fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
	}

	dh_gen_key(dh, kex->we_need * 8);

	do {
		debug("Wait SSH2_MSG_GSSAPI_INIT");
		type = packet_read();
		switch(type) {
		case SSH2_MSG_KEXGSS_INIT:
			if (dh_client_pub != NULL) 
				fatal("Received KEXGSS_INIT after initialising");
			recv_tok.value = packet_get_string(&slen);
			recv_tok.length = slen; 

			if ((dh_client_pub = BN_new()) == NULL)
				fatal("dh_client_pub == NULL");

			packet_get_bignum2(dh_client_pub);

			/* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
			break;
		case SSH2_MSG_KEXGSS_CONTINUE:
			recv_tok.value = packet_get_string(&slen);
			recv_tok.length = slen; 
			break;
		default:
			packet_disconnect(
			    "Protocol error: didn't expect packet type %d",
			    type);
		}

		maj_status = PRIVSEP(ssh_gssapi_accept_ctx(ctxt, &recv_tok, 
		    &send_tok, &ret_flags));

		xfree(recv_tok.value);

		if (maj_status != GSS_S_COMPLETE && send_tok.length == 0)
			fatal("Zero length token output when incomplete");

		if (dh_client_pub == NULL)
			fatal("No client public key");
		
		if (maj_status & GSS_S_CONTINUE_NEEDED) {
			debug("Sending GSSAPI_CONTINUE");
			packet_start(SSH2_MSG_KEXGSS_CONTINUE);
			packet_put_string(send_tok.value, send_tok.length);
			packet_send();
			gss_release_buffer(&min_status, &send_tok);
		}
	} while (maj_status & GSS_S_CONTINUE_NEEDED);

	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);
			packet_send();
		}
		fatal("accept_ctx died");
	}

	if (!(ret_flags & GSS_C_MUTUAL_FLAG))
		fatal("Mutual Authentication flag wasn't set");

	if (!(ret_flags & GSS_C_INTEG_FLAG))
		fatal("Integrity flag wasn't set");
	
	if (!dh_pub_is_valid(dh, dh_client_pub))
		packet_disconnect("bad client public DH value");

	klen = DH_size(dh);
	kbuf = xmalloc(klen); 
	kout = DH_compute_key(kbuf, dh_client_pub, dh);

	shared_secret = BN_new();
	BN_bin2bn(kbuf, kout, shared_secret);
	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->peer), buffer_len(&kex->peer),
		    buffer_ptr(&kex->my), buffer_len(&kex->my),
		    NULL, 0, /* Change this if we start sending host keys */
		    dh_client_pub, dh->pub_key, shared_secret,
		    &hash, &hashlen
		);
		break;
	case KEX_GSS_GEX_SHA1:
		kexgex_hash(
		    kex->evp_md,
		    kex->client_version_string, kex->server_version_string,
		    buffer_ptr(&kex->peer), buffer_len(&kex->peer),
		    buffer_ptr(&kex->my), buffer_len(&kex->my),
		    NULL, 0,
		    min, nbits, max,
		    dh->p, dh->g,
		    dh_client_pub,
		    dh->pub_key,
		    shared_secret,
		    &hash, &hashlen
		);
		break;
	default:
		fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
	}

	BN_free(dh_client_pub);

	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);
	}

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

	if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt,&gssbuf,&msg_tok))))
		fatal("Couldn't get MIC");

	packet_start(SSH2_MSG_KEXGSS_COMPLETE);
	packet_put_bignum2(dh->pub_key);
	packet_put_string(msg_tok.value,msg_tok.length);

	if (send_tok.length != 0) {
		packet_put_char(1); /* true */
		packet_put_string(send_tok.value, send_tok.length);
	} else {
		packet_put_char(0); /* false */
	}
	packet_send();

	gss_release_buffer(&min_status, &send_tok);
	gss_release_buffer(&min_status, &msg_tok);

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

	DH_free(dh);

	kex_derive_keys(kex, hash, hashlen, shared_secret);
	BN_clear_free(shared_secret);
	kex_finish(kex);
}
#endif /* GSSAPI */
Commit	Line	Data
659bdb8e	1	/*
	2	* Copyright (c) 2001-2006 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 <string.h>
	30
	31	#include <openssl/crypto.h>
	32	#include <openssl/bn.h>
	33
	34	#include "xmalloc.h"
	35	#include "buffer.h"
	36	#include "ssh2.h"
	37	#include "key.h"
	38	#include "cipher.h"
	39	#include "kex.h"
	40	#include "log.h"
	41	#include "packet.h"
	42	#include "dh.h"
	43	#include "ssh-gss.h"
	44	#include "monitor_wrap.h"
	45
	46	void
	47	kexgss_server(Kex *kex)
	48	{
	49	OM_uint32 maj_status, min_status;
	50
	51	/*
	52	* Some GSSAPI implementations use the input value of ret_flags (an
	53	* output variable) as a means of triggering mechanism specific
	54	* features. Initializing it to zero avoids inadvertently
	55	* activating this non-standard behaviour.
	56	*/
	57
	58	OM_uint32 ret_flags = 0;
	59	gss_buffer_desc gssbuf, recv_tok, msg_tok;
	60	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
	61	Gssctxt *ctxt = NULL;
	62	u_int slen, klen, kout, hashlen;
	63	u_char kbuf, hash;
	64	DH *dh;
65	int min = -1, max = -1, nbits = -1;
66	BIGNUM *shared_secret = NULL;
67	BIGNUM *dh_client_pub = NULL;
68	int type = 0;
69	gss_OID oid;
70
71	/* Initialise GSSAPI */
72
73	/* If we're rekeying, privsep means that some of the private structures
74	* in the GSSAPI code are no longer available. This kludges them back
75	* into life
76	*/
77	if (!ssh_gssapi_oid_table_ok())
78	ssh_gssapi_server_mechanisms();
79
80	debug2("%s: Identifying %s", __func__, kex->name);
81	oid = ssh_gssapi_id_kex(NULL, kex->name, kex->kex_type);
82	if (oid == GSS_C_NO_OID)
83	fatal("Unknown gssapi mechanism");
84
85	debug2("%s: Acquiring credentials", __func__);
86
87	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, oid))))
88	fatal("Unable to acquire credentials for the server");
89
90	switch (kex->kex_type) {
91	case KEX_GSS_GRP1_SHA1:
92	dh = dh_new_group1();
93	break;
94	case KEX_GSS_GRP14_SHA1:
95	dh = dh_new_group14();
96	break;
97	case KEX_GSS_GEX_SHA1:
98	debug("Doing group exchange");
99	packet_read_expect(SSH2_MSG_KEXGSS_GROUPREQ);
100	min = packet_get_int();
101	nbits = packet_get_int();
102	max = packet_get_int();
103	min = MAX(DH_GRP_MIN, min);
104	max = MIN(DH_GRP_MAX, max);
105	packet_check_eom();
106	if (max < min \|\| nbits < min \|\| max < nbits)
107	fatal("GSS_GEX, bad parameters: %d !< %d !< %d",
108	min, nbits, max);
109	dh = PRIVSEP(choose_dh(min, nbits, max));
110	if (dh == NULL)
111	packet_disconnect("Protocol error: no matching group found");
112
113	packet_start(SSH2_MSG_KEXGSS_GROUP);
114	packet_put_bignum2(dh->p);
115	packet_put_bignum2(dh->g);
116	packet_send();
117
118	packet_write_wait();
119	break;
120	default:
121	fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
122	}
123
124	dh_gen_key(dh, kex->we_need * 8);
125
126	do {
127	debug("Wait SSH2_MSG_GSSAPI_INIT");
128	type = packet_read();
129	switch(type) {
130	case SSH2_MSG_KEXGSS_INIT:
131	if (dh_client_pub != NULL)
132	fatal("Received KEXGSS_INIT after initialising");
133	recv_tok.value = packet_get_string(&slen);
134	recv_tok.length = slen;
135
136	if ((dh_client_pub = BN_new()) == NULL)
137	fatal("dh_client_pub == NULL");
138
139	packet_get_bignum2(dh_client_pub);
140
141	/* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
142	break;
143	case SSH2_MSG_KEXGSS_CONTINUE:
144	recv_tok.value = packet_get_string(&slen);
145	recv_tok.length = slen;
146	break;
147	default:
148	packet_disconnect(
149	"Protocol error: didn't expect packet type %d",
150	type);
151	}
152
153	maj_status = PRIVSEP(ssh_gssapi_accept_ctx(ctxt, &recv_tok,
154	&send_tok, &ret_flags));
155
156	xfree(recv_tok.value);
157
158	if (maj_status != GSS_S_COMPLETE && send_tok.length == 0)
159	fatal("Zero length token output when incomplete");
160
161	if (dh_client_pub == NULL)
162	fatal("No client public key");
163
164	if (maj_status & GSS_S_CONTINUE_NEEDED) {
165	debug("Sending GSSAPI_CONTINUE");
166	packet_start(SSH2_MSG_KEXGSS_CONTINUE);
167	packet_put_string(send_tok.value, send_tok.length);
168	packet_send();
169	gss_release_buffer(&min_status, &send_tok);
170	}
171	} while (maj_status & GSS_S_CONTINUE_NEEDED);
172
173	if (GSS_ERROR(maj_status)) {
174	if (send_tok.length > 0) {
175	packet_start(SSH2_MSG_KEXGSS_CONTINUE);
176	packet_put_string(send_tok.value, send_tok.length);
177	packet_send();
178	}
179	fatal("accept_ctx died");
180	}
181
182	if (!(ret_flags & GSS_C_MUTUAL_FLAG))
183	fatal("Mutual Authentication flag wasn't set");
184
185	if (!(ret_flags & GSS_C_INTEG_FLAG))
186	fatal("Integrity flag wasn't set");
187
188	if (!dh_pub_is_valid(dh, dh_client_pub))
189	packet_disconnect("bad client public DH value");
190
191	klen = DH_size(dh);
192	kbuf = xmalloc(klen);
193	kout = DH_compute_key(kbuf, dh_client_pub, dh);
194
195	shared_secret = BN_new();
196	BN_bin2bn(kbuf, kout, shared_secret);
197	memset(kbuf, 0, klen);
198	xfree(kbuf);
199
200	switch (kex->kex_type) {
201	case KEX_GSS_GRP1_SHA1:
202	case KEX_GSS_GRP14_SHA1:
203	kex_dh_hash(
204	kex->client_version_string, kex->server_version_string,
205	buffer_ptr(&kex->peer), buffer_len(&kex->peer),
206	buffer_ptr(&kex->my), buffer_len(&kex->my),
207	NULL, 0, /* Change this if we start sending host keys */
208	dh_client_pub, dh->pub_key, shared_secret,
209	&hash, &hashlen
210	);
211	break;
212	case KEX_GSS_GEX_SHA1:
213	kexgex_hash(
214	kex->evp_md,
215	kex->client_version_string, kex->server_version_string,
216	buffer_ptr(&kex->peer), buffer_len(&kex->peer),
217	buffer_ptr(&kex->my), buffer_len(&kex->my),
218	NULL, 0,
219	min, nbits, max,
220	dh->p, dh->g,
221	dh_client_pub,
222	dh->pub_key,
223	shared_secret,
224	&hash, &hashlen
225	);
226	break;
227	default:
228	fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
229	}
230
231	BN_free(dh_client_pub);
232
233	if (kex->session_id == NULL) {
234	kex->session_id_len = hashlen;
235	kex->session_id = xmalloc(kex->session_id_len);
236	memcpy(kex->session_id, hash, kex->session_id_len);
237	}
238
239	gssbuf.value = hash;
240	gssbuf.length = hashlen;
241
242	if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt,&gssbuf,&msg_tok))))
243	fatal("Couldn't get MIC");
244
245	packet_start(SSH2_MSG_KEXGSS_COMPLETE);
246	packet_put_bignum2(dh->pub_key);
247	packet_put_string(msg_tok.value,msg_tok.length);
248
249	if (send_tok.length != 0) {
250	packet_put_char(1); /* true */
251	packet_put_string(send_tok.value, send_tok.length);
252	} else {
253	packet_put_char(0); /* false */
254	}
255	packet_send();
256
257	gss_release_buffer(&min_status, &send_tok);
258	gss_release_buffer(&min_status, &msg_tok);
259
260	if (gss_kex_context == NULL)
261	gss_kex_context = ctxt;
262	else
263	ssh_gssapi_delete_ctx(&ctxt);
264
265	DH_free(dh);
266
267	kex_derive_keys(kex, hash, hashlen, shared_secret);
268	BN_clear_free(shared_secret);
269	kex_finish(kex);
270	}
271	#endif /* GSSAPI */