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

/* $OpenBSD: kexgexc.c,v 1.9 2006/08/03 03:34:42 deraadt Exp $ */
/*
 * Copyright (c) 2000 Niels Provos.  All rights reserved.
 * Copyright (c) 2001 Markus Friedl.  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"

#include <sys/types.h>

#include <stdarg.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>

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

void
kexgex_client(Kex *kex)
{
	BIGNUM *dh_server_pub = NULL, *shared_secret = NULL;
	BIGNUM *p = NULL, *g = NULL;
	Key *server_host_key;
	u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
	u_int klen, kout, slen, sbloblen, hashlen;
	int min, max, nbits;
	DH *dh;

	nbits = dh_estimate(kex->we_need * 8);

	if (datafellows & SSH_OLD_DHGEX) {
		/* Old GEX request */
		packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD);
		packet_put_int(nbits);
		min = DH_GRP_MIN;
		max = DH_GRP_MAX;

		debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", nbits);
	} else {
		/* New GEX request */
		min = DH_GRP_MIN;
		max = DH_GRP_MAX;
		packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
		packet_put_int(min);
		packet_put_int(nbits);
		packet_put_int(max);

		debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
		    min, nbits, max);
	}
#ifdef DEBUG_KEXDH
	fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
	    min, nbits, max);
#endif
	packet_send();

	debug("expecting SSH2_MSG_KEX_DH_GEX_GROUP");
	packet_read_expect(SSH2_MSG_KEX_DH_GEX_GROUP);

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

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

	dh = dh_new_group(g, p);
	dh_gen_key(dh, kex->we_need * 8);

#ifdef DEBUG_KEXDH
	DHparams_print_fp(stderr, dh);
	fprintf(stderr, "pub= ");
	BN_print_fp(stderr, dh->pub_key);
	fprintf(stderr, "\n");
#endif

	debug("SSH2_MSG_KEX_DH_GEX_INIT sent");
	/* generate and send 'e', client DH public key */
	packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
	packet_put_bignum2(dh->pub_key);
	packet_send();

	debug("expecting SSH2_MSG_KEX_DH_GEX_REPLY");
	packet_read_expect(SSH2_MSG_KEX_DH_GEX_REPLY);

	/* key, cert */
	server_host_key_blob = packet_get_string(&sbloblen);
	server_host_key = key_from_blob(server_host_key_blob, sbloblen);
	if (server_host_key == NULL)
		fatal("cannot decode server_host_key_blob");
	if (server_host_key->type != kex->hostkey_type)
		fatal("type mismatch for decoded server_host_key_blob");
	if (kex->verify_host_key == NULL)
		fatal("cannot verify server_host_key");
	if (kex->verify_host_key(server_host_key) == -1)
		fatal("server_host_key verification failed");

	/* DH parameter f, server public DH key */
	if ((dh_server_pub = BN_new()) == NULL)
		fatal("dh_server_pub == NULL");
	packet_get_bignum2(dh_server_pub);

#ifdef DEBUG_KEXDH
	fprintf(stderr, "dh_server_pub= ");
	BN_print_fp(stderr, dh_server_pub);
	fprintf(stderr, "\n");
	debug("bits %d", BN_num_bits(dh_server_pub));
#endif

	/* signed H */
	signature = packet_get_string(&slen);
	packet_check_eom();

	if (!dh_pub_is_valid(dh, dh_server_pub))
		packet_disconnect("bad server public DH value");

	klen = DH_size(dh);
	kbuf = xmalloc(klen);
	kout = DH_compute_key(kbuf, dh_server_pub, dh);
#ifdef DEBUG_KEXDH
	dump_digest("shared secret", kbuf, kout);
#endif
	if ((shared_secret = BN_new()) == NULL)
		fatal("kexgex_client: BN_new failed");
	BN_bin2bn(kbuf, kout, shared_secret);
	memset(kbuf, 0, klen);
	xfree(kbuf);

	if (datafellows & SSH_OLD_DHGEX)
		min = max = -1;

	/* calc and verify H */
	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),
	    server_host_key_blob, sbloblen,
	    min, nbits, max,
	    dh->p, dh->g,
	    dh->pub_key,
	    dh_server_pub,
	    shared_secret,
	    &hash, &hashlen
	);

	/* have keys, free DH */
	DH_free(dh);
	xfree(server_host_key_blob);
	BN_clear_free(dh_server_pub);

	if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
		fatal("key_verify failed for server_host_key");
	key_free(server_host_key);
	xfree(signature);

	/* 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);
	}
	kex_derive_keys(kex, hash, hashlen, shared_secret);
	BN_clear_free(shared_secret);

	kex_finish(kex);
}
Commit	Line	Data
9108f8d9	1	/* $OpenBSD: kexgexc.c,v 1.9 2006/08/03 03:34:42 deraadt Exp $ */
6a9b3198	2	/*
	3	* Copyright (c) 2000 Niels Provos. All rights reserved.
	4	* Copyright (c) 2001 Markus Friedl. 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"
9108f8d9	28
	29	#include <sys/types.h>
	30
	31	#include <stdarg.h>
	32	#include <stdio.h>
	33	#include <string.h>
	34	#include <signal.h>
6a9b3198	35
6a9b3198	36	#include "xmalloc.h"
9108f8d9	37	#include "buffer.h"
6a9b3198	38	#include "key.h"
9108f8d9	39	#include "cipher.h"
6a9b3198	40	#include "kex.h"
	41	#include "log.h"
	42	#include "packet.h"
	43	#include "dh.h"
	44	#include "ssh2.h"
	45	#include "compat.h"
	46
	47	void
	48	kexgex_client(Kex *kex)
	49	{
	50	BIGNUM dh_server_pub = NULL, shared_secret = NULL;
	51	BIGNUM p = NULL, g = NULL;
	52	Key *server_host_key;
	53	u_char kbuf, hash, signature = NULL, server_host_key_blob = NULL;
2c06c99b	54	u_int klen, kout, slen, sbloblen, hashlen;
6a9b3198	55	int min, max, nbits;
	56	DH *dh;
	57
	58	nbits = dh_estimate(kex->we_need * 8);
	59
	60	if (datafellows & SSH_OLD_DHGEX) {
6a9b3198	61	/* Old GEX request */
	62	packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST_OLD);
	63	packet_put_int(nbits);
	64	min = DH_GRP_MIN;
	65	max = DH_GRP_MAX;
9cb1827b	66
cdd66111	67	debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD(%u) sent", nbits);
cdd66111	68	} else {
6a9b3198	69	/* New GEX request */
	70	min = DH_GRP_MIN;
	71	max = DH_GRP_MAX;
	72	packet_start(SSH2_MSG_KEX_DH_GEX_REQUEST);
	73	packet_put_int(min);
	74	packet_put_int(nbits);
	75	packet_put_int(max);
cdd66111	76
	77	debug("SSH2_MSG_KEX_DH_GEX_REQUEST(%u<%u<%u) sent",
	78	min, nbits, max);
6a9b3198	79	}
	80	#ifdef DEBUG_KEXDH
	81	fprintf(stderr, "\nmin = %d, nbits = %d, max = %d\n",
	82	min, nbits, max);
	83	#endif
	84	packet_send();
	85
	86	debug("expecting SSH2_MSG_KEX_DH_GEX_GROUP");
	87	packet_read_expect(SSH2_MSG_KEX_DH_GEX_GROUP);
	88
	89	if ((p = BN_new()) == NULL)
	90	fatal("BN_new");
	91	packet_get_bignum2(p);
	92	if ((g = BN_new()) == NULL)
	93	fatal("BN_new");
	94	packet_get_bignum2(g);
	95	packet_check_eom();
	96
	97	if (BN_num_bits(p) < min \|\| BN_num_bits(p) > max)
	98	fatal("DH_GEX group out of range: %d !< %d !< %d",
	99	min, BN_num_bits(p), max);
	100
	101	dh = dh_new_group(g, p);
	102	dh_gen_key(dh, kex->we_need * 8);
	103
	104	#ifdef DEBUG_KEXDH
	105	DHparams_print_fp(stderr, dh);
	106	fprintf(stderr, "pub= ");
	107	BN_print_fp(stderr, dh->pub_key);
	108	fprintf(stderr, "\n");
	109	#endif
	110
	111	debug("SSH2_MSG_KEX_DH_GEX_INIT sent");
	112	/* generate and send 'e', client DH public key */
	113	packet_start(SSH2_MSG_KEX_DH_GEX_INIT);
	114	packet_put_bignum2(dh->pub_key);
	115	packet_send();
	116
	117	debug("expecting SSH2_MSG_KEX_DH_GEX_REPLY");
	118	packet_read_expect(SSH2_MSG_KEX_DH_GEX_REPLY);
	119
	120	/* key, cert */
	121	server_host_key_blob = packet_get_string(&sbloblen);
	122	server_host_key = key_from_blob(server_host_key_blob, sbloblen);
	123	if (server_host_key == NULL)
	124	fatal("cannot decode server_host_key_blob");
	125	if (server_host_key->type != kex->hostkey_type)
	126	fatal("type mismatch for decoded server_host_key_blob");
	127	if (kex->verify_host_key == NULL)
	128	fatal("cannot verify server_host_key");
	129	if (kex->verify_host_key(server_host_key) == -1)
	130	fatal("server_host_key verification failed");
	131
9108f8d9	132	/* DH parameter f, server public DH key */
6a9b3198	133	if ((dh_server_pub = BN_new()) == NULL)
	134	fatal("dh_server_pub == NULL");
	135	packet_get_bignum2(dh_server_pub);
	136
	137	#ifdef DEBUG_KEXDH
	138	fprintf(stderr, "dh_server_pub= ");
	139	BN_print_fp(stderr, dh_server_pub);
	140	fprintf(stderr, "\n");
	141	debug("bits %d", BN_num_bits(dh_server_pub));
	142	#endif
	143
	144	/* signed H */
	145	signature = packet_get_string(&slen);
	146	packet_check_eom();
	147
	148	if (!dh_pub_is_valid(dh, dh_server_pub))
	149	packet_disconnect("bad server public DH value");
	150
	151	klen = DH_size(dh);
	152	kbuf = xmalloc(klen);
	153	kout = DH_compute_key(kbuf, dh_server_pub, dh);
	154	#ifdef DEBUG_KEXDH
	155	dump_digest("shared secret", kbuf, kout);
	156	#endif
	157	if ((shared_secret = BN_new()) == NULL)
	158	fatal("kexgex_client: BN_new failed");
	159	BN_bin2bn(kbuf, kout, shared_secret);
	160	memset(kbuf, 0, klen);
	161	xfree(kbuf);
	162
	163	if (datafellows & SSH_OLD_DHGEX)
	164	min = max = -1;
	165
	166	/* calc and verify H */
2c06c99b	167	kexgex_hash(
2c06c99b	168	kex->evp_md,
6a9b3198	169	kex->client_version_string,
	170	kex->server_version_string,
	171	buffer_ptr(&kex->my), buffer_len(&kex->my),
	172	buffer_ptr(&kex->peer), buffer_len(&kex->peer),
	173	server_host_key_blob, sbloblen,
	174	min, nbits, max,
	175	dh->p, dh->g,
	176	dh->pub_key,
	177	dh_server_pub,
2c06c99b	178	shared_secret,
2c06c99b	179	&hash, &hashlen
6a9b3198	180	);
2c06c99b	181
6a9b3198	182	/* have keys, free DH */
	183	DH_free(dh);
	184	xfree(server_host_key_blob);
	185	BN_clear_free(dh_server_pub);
	186
2c06c99b	187	if (key_verify(server_host_key, signature, slen, hash, hashlen) != 1)
6a9b3198	188	fatal("key_verify failed for server_host_key");
	189	key_free(server_host_key);
	190	xfree(signature);
	191
	192	/* save session id */
	193	if (kex->session_id == NULL) {
2c06c99b	194	kex->session_id_len = hashlen;
6a9b3198	195	kex->session_id = xmalloc(kex->session_id_len);
	196	memcpy(kex->session_id, hash, kex->session_id_len);
	197	}
2c06c99b	198	kex_derive_keys(kex, hash, hashlen, shared_secret);
6a9b3198	199	BN_clear_free(shared_secret);
	200
	201	kex_finish(kex);
	202	}