xref: /freebsd/crypto/openssh/kex.c (revision 761efaa70c2ed8d35722b7bc234a46bf2457f876)
1761efaa7SDag-Erling Smørgrav /* $OpenBSD: kex.c,v 1.76 2006/08/03 03:34:42 deraadt Exp $ */
2a04a10f8SKris Kennaway /*
3ae1f160dSDag-Erling Smørgrav  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
4a04a10f8SKris Kennaway  *
5a04a10f8SKris Kennaway  * Redistribution and use in source and binary forms, with or without
6a04a10f8SKris Kennaway  * modification, are permitted provided that the following conditions
7a04a10f8SKris Kennaway  * are met:
8a04a10f8SKris Kennaway  * 1. Redistributions of source code must retain the above copyright
9a04a10f8SKris Kennaway  *    notice, this list of conditions and the following disclaimer.
10a04a10f8SKris Kennaway  * 2. Redistributions in binary form must reproduce the above copyright
11a04a10f8SKris Kennaway  *    notice, this list of conditions and the following disclaimer in the
12a04a10f8SKris Kennaway  *    documentation and/or other materials provided with the distribution.
13a04a10f8SKris Kennaway  *
14a04a10f8SKris Kennaway  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15a04a10f8SKris Kennaway  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16a04a10f8SKris Kennaway  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17a04a10f8SKris Kennaway  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18a04a10f8SKris Kennaway  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19a04a10f8SKris Kennaway  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20a04a10f8SKris Kennaway  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21a04a10f8SKris Kennaway  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22a04a10f8SKris Kennaway  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23a04a10f8SKris Kennaway  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24a04a10f8SKris Kennaway  */
25a04a10f8SKris Kennaway 
26a04a10f8SKris Kennaway #include "includes.h"
27761efaa7SDag-Erling Smørgrav 
28761efaa7SDag-Erling Smørgrav #include <sys/param.h>
29761efaa7SDag-Erling Smørgrav 
30761efaa7SDag-Erling Smørgrav #include <signal.h>
31761efaa7SDag-Erling Smørgrav #include <stdarg.h>
32761efaa7SDag-Erling Smørgrav #include <stdio.h>
33761efaa7SDag-Erling Smørgrav #include <stdlib.h>
34761efaa7SDag-Erling Smørgrav #include <string.h>
35a04a10f8SKris Kennaway 
361e8db6e2SBrian Feldman #include <openssl/crypto.h>
371e8db6e2SBrian Feldman 
38a04a10f8SKris Kennaway #include "xmalloc.h"
39761efaa7SDag-Erling Smørgrav #include "ssh2.h"
40a04a10f8SKris Kennaway #include "buffer.h"
412632b0c8SKris Kennaway #include "packet.h"
42a04a10f8SKris Kennaway #include "compat.h"
431e8db6e2SBrian Feldman #include "cipher.h"
441e8db6e2SBrian Feldman #include "key.h"
45761efaa7SDag-Erling Smørgrav #include "kex.h"
461e8db6e2SBrian Feldman #include "log.h"
471e8db6e2SBrian Feldman #include "mac.h"
481e8db6e2SBrian Feldman #include "match.h"
491e8db6e2SBrian Feldman #include "dispatch.h"
50545d5ecaSDag-Erling Smørgrav #include "monitor.h"
51a04a10f8SKris Kennaway 
522632b0c8SKris Kennaway #define KEX_COOKIE_LEN	16
532632b0c8SKris Kennaway 
54761efaa7SDag-Erling Smørgrav #if OPENSSL_VERSION_NUMBER >= 0x00907000L
55761efaa7SDag-Erling Smørgrav # if defined(HAVE_EVP_SHA256)
56761efaa7SDag-Erling Smørgrav # define evp_ssh_sha256 EVP_sha256
57761efaa7SDag-Erling Smørgrav # else
58761efaa7SDag-Erling Smørgrav extern const EVP_MD *evp_ssh_sha256(void);
59761efaa7SDag-Erling Smørgrav # endif
60761efaa7SDag-Erling Smørgrav #endif
61761efaa7SDag-Erling Smørgrav 
62ae1f160dSDag-Erling Smørgrav /* prototype */
63ae1f160dSDag-Erling Smørgrav static void kex_kexinit_finish(Kex *);
64ae1f160dSDag-Erling Smørgrav static void kex_choose_conf(Kex *);
651e8db6e2SBrian Feldman 
661e8db6e2SBrian Feldman /* put algorithm proposal into buffer */
67ae1f160dSDag-Erling Smørgrav static void
681e8db6e2SBrian Feldman kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
69a04a10f8SKris Kennaway {
70043840dfSDag-Erling Smørgrav 	u_int i;
711e8db6e2SBrian Feldman 
721e8db6e2SBrian Feldman 	buffer_clear(b);
73545d5ecaSDag-Erling Smørgrav 	/*
74545d5ecaSDag-Erling Smørgrav 	 * add a dummy cookie, the cookie will be overwritten by
75545d5ecaSDag-Erling Smørgrav 	 * kex_send_kexinit(), each time a kexinit is set
76545d5ecaSDag-Erling Smørgrav 	 */
77545d5ecaSDag-Erling Smørgrav 	for (i = 0; i < KEX_COOKIE_LEN; i++)
78545d5ecaSDag-Erling Smørgrav 		buffer_put_char(b, 0);
79a04a10f8SKris Kennaway 	for (i = 0; i < PROPOSAL_MAX; i++)
801e8db6e2SBrian Feldman 		buffer_put_cstring(b, proposal[i]);
811e8db6e2SBrian Feldman 	buffer_put_char(b, 0);			/* first_kex_packet_follows */
821e8db6e2SBrian Feldman 	buffer_put_int(b, 0);			/* uint32 reserved */
83a04a10f8SKris Kennaway }
84a04a10f8SKris Kennaway 
851e8db6e2SBrian Feldman /* parse buffer and return algorithm proposal */
86ae1f160dSDag-Erling Smørgrav static char **
87d0c8c0bcSDag-Erling Smørgrav kex_buf2prop(Buffer *raw, int *first_kex_follows)
882632b0c8SKris Kennaway {
891e8db6e2SBrian Feldman 	Buffer b;
902632b0c8SKris Kennaway 	int i;
911e8db6e2SBrian Feldman 	char **proposal;
922632b0c8SKris Kennaway 
93761efaa7SDag-Erling Smørgrav 	proposal = xcalloc(PROPOSAL_MAX, sizeof(char *));
942632b0c8SKris Kennaway 
951e8db6e2SBrian Feldman 	buffer_init(&b);
961e8db6e2SBrian Feldman 	buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
972632b0c8SKris Kennaway 	/* skip cookie */
982632b0c8SKris Kennaway 	for (i = 0; i < KEX_COOKIE_LEN; i++)
991e8db6e2SBrian Feldman 		buffer_get_char(&b);
1002632b0c8SKris Kennaway 	/* extract kex init proposal strings */
1012632b0c8SKris Kennaway 	for (i = 0; i < PROPOSAL_MAX; i++) {
1021e8db6e2SBrian Feldman 		proposal[i] = buffer_get_string(&b,NULL);
1031e8db6e2SBrian Feldman 		debug2("kex_parse_kexinit: %s", proposal[i]);
1042632b0c8SKris Kennaway 	}
1051e8db6e2SBrian Feldman 	/* first kex follows / reserved */
1061e8db6e2SBrian Feldman 	i = buffer_get_char(&b);
107d0c8c0bcSDag-Erling Smørgrav 	if (first_kex_follows != NULL)
108d0c8c0bcSDag-Erling Smørgrav 		*first_kex_follows = i;
1091e8db6e2SBrian Feldman 	debug2("kex_parse_kexinit: first_kex_follows %d ", i);
1101e8db6e2SBrian Feldman 	i = buffer_get_int(&b);
1111e8db6e2SBrian Feldman 	debug2("kex_parse_kexinit: reserved %d ", i);
1121e8db6e2SBrian Feldman 	buffer_free(&b);
1131e8db6e2SBrian Feldman 	return proposal;
1145b9b2fafSBrian Feldman }
1155b9b2fafSBrian Feldman 
116ae1f160dSDag-Erling Smørgrav static void
1171e8db6e2SBrian Feldman kex_prop_free(char **proposal)
118a04a10f8SKris Kennaway {
119043840dfSDag-Erling Smørgrav 	u_int i;
1201e8db6e2SBrian Feldman 
1211e8db6e2SBrian Feldman 	for (i = 0; i < PROPOSAL_MAX; i++)
1221e8db6e2SBrian Feldman 		xfree(proposal[i]);
1231e8db6e2SBrian Feldman 	xfree(proposal);
124a04a10f8SKris Kennaway }
125a04a10f8SKris Kennaway 
126ae1f160dSDag-Erling Smørgrav static void
127ae1f160dSDag-Erling Smørgrav kex_protocol_error(int type, u_int32_t seq, void *ctxt)
128a04a10f8SKris Kennaway {
129ae1f160dSDag-Erling Smørgrav 	error("Hm, kex protocol error: type %d seq %u", type, seq);
130a04a10f8SKris Kennaway }
131a04a10f8SKris Kennaway 
132ae1f160dSDag-Erling Smørgrav static void
133ae1f160dSDag-Erling Smørgrav kex_reset_dispatch(void)
1345b9b2fafSBrian Feldman {
135ae1f160dSDag-Erling Smørgrav 	dispatch_range(SSH2_MSG_TRANSPORT_MIN,
136ae1f160dSDag-Erling Smørgrav 	    SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
137ae1f160dSDag-Erling Smørgrav 	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
1385b9b2fafSBrian Feldman }
1395b9b2fafSBrian Feldman 
1401e8db6e2SBrian Feldman void
1411e8db6e2SBrian Feldman kex_finish(Kex *kex)
142a04a10f8SKris Kennaway {
143ae1f160dSDag-Erling Smørgrav 	kex_reset_dispatch();
144a04a10f8SKris Kennaway 
1451e8db6e2SBrian Feldman 	packet_start(SSH2_MSG_NEWKEYS);
1461e8db6e2SBrian Feldman 	packet_send();
1471e8db6e2SBrian Feldman 	/* packet_write_wait(); */
1481e8db6e2SBrian Feldman 	debug("SSH2_MSG_NEWKEYS sent");
149a04a10f8SKris Kennaway 
150d0c8c0bcSDag-Erling Smørgrav 	debug("expecting SSH2_MSG_NEWKEYS");
151ae1f160dSDag-Erling Smørgrav 	packet_read_expect(SSH2_MSG_NEWKEYS);
152ae1f160dSDag-Erling Smørgrav 	packet_check_eom();
1531e8db6e2SBrian Feldman 	debug("SSH2_MSG_NEWKEYS received");
1541e8db6e2SBrian Feldman 
1551e8db6e2SBrian Feldman 	kex->done = 1;
1561e8db6e2SBrian Feldman 	buffer_clear(&kex->peer);
1571e8db6e2SBrian Feldman 	/* buffer_clear(&kex->my); */
1581e8db6e2SBrian Feldman 	kex->flags &= ~KEX_INIT_SENT;
1591e8db6e2SBrian Feldman 	xfree(kex->name);
1601e8db6e2SBrian Feldman 	kex->name = NULL;
161a04a10f8SKris Kennaway }
162a04a10f8SKris Kennaway 
1631e8db6e2SBrian Feldman void
1641e8db6e2SBrian Feldman kex_send_kexinit(Kex *kex)
165a04a10f8SKris Kennaway {
166d74d50a8SDag-Erling Smørgrav 	u_int32_t rnd = 0;
167545d5ecaSDag-Erling Smørgrav 	u_char *cookie;
168043840dfSDag-Erling Smørgrav 	u_int i;
169545d5ecaSDag-Erling Smørgrav 
1701e8db6e2SBrian Feldman 	if (kex == NULL) {
1711e8db6e2SBrian Feldman 		error("kex_send_kexinit: no kex, cannot rekey");
1721e8db6e2SBrian Feldman 		return;
1731e8db6e2SBrian Feldman 	}
1741e8db6e2SBrian Feldman 	if (kex->flags & KEX_INIT_SENT) {
1751e8db6e2SBrian Feldman 		debug("KEX_INIT_SENT");
1761e8db6e2SBrian Feldman 		return;
1771e8db6e2SBrian Feldman 	}
1781e8db6e2SBrian Feldman 	kex->done = 0;
179545d5ecaSDag-Erling Smørgrav 
180545d5ecaSDag-Erling Smørgrav 	/* generate a random cookie */
181545d5ecaSDag-Erling Smørgrav 	if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
182545d5ecaSDag-Erling Smørgrav 		fatal("kex_send_kexinit: kex proposal too short");
183545d5ecaSDag-Erling Smørgrav 	cookie = buffer_ptr(&kex->my);
184545d5ecaSDag-Erling Smørgrav 	for (i = 0; i < KEX_COOKIE_LEN; i++) {
185545d5ecaSDag-Erling Smørgrav 		if (i % 4 == 0)
186d74d50a8SDag-Erling Smørgrav 			rnd = arc4random();
187d74d50a8SDag-Erling Smørgrav 		cookie[i] = rnd;
188d74d50a8SDag-Erling Smørgrav 		rnd >>= 8;
189545d5ecaSDag-Erling Smørgrav 	}
1901e8db6e2SBrian Feldman 	packet_start(SSH2_MSG_KEXINIT);
1911e8db6e2SBrian Feldman 	packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
1921e8db6e2SBrian Feldman 	packet_send();
1931e8db6e2SBrian Feldman 	debug("SSH2_MSG_KEXINIT sent");
1941e8db6e2SBrian Feldman 	kex->flags |= KEX_INIT_SENT;
1951e8db6e2SBrian Feldman }
196a04a10f8SKris Kennaway 
1971e8db6e2SBrian Feldman void
198ae1f160dSDag-Erling Smørgrav kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
1991e8db6e2SBrian Feldman {
2001e8db6e2SBrian Feldman 	char *ptr;
201043840dfSDag-Erling Smørgrav 	u_int i, dlen;
2021e8db6e2SBrian Feldman 	Kex *kex = (Kex *)ctxt;
2032632b0c8SKris Kennaway 
2041e8db6e2SBrian Feldman 	debug("SSH2_MSG_KEXINIT received");
2051e8db6e2SBrian Feldman 	if (kex == NULL)
2061e8db6e2SBrian Feldman 		fatal("kex_input_kexinit: no kex, cannot rekey");
2071e8db6e2SBrian Feldman 
2081e8db6e2SBrian Feldman 	ptr = packet_get_raw(&dlen);
2091e8db6e2SBrian Feldman 	buffer_append(&kex->peer, ptr, dlen);
2101e8db6e2SBrian Feldman 
2111e8db6e2SBrian Feldman 	/* discard packet */
2121e8db6e2SBrian Feldman 	for (i = 0; i < KEX_COOKIE_LEN; i++)
2131e8db6e2SBrian Feldman 		packet_get_char();
2141e8db6e2SBrian Feldman 	for (i = 0; i < PROPOSAL_MAX; i++)
2151e8db6e2SBrian Feldman 		xfree(packet_get_string(NULL));
216ee21a45fSDag-Erling Smørgrav 	(void) packet_get_char();
217ee21a45fSDag-Erling Smørgrav 	(void) packet_get_int();
218ae1f160dSDag-Erling Smørgrav 	packet_check_eom();
2191e8db6e2SBrian Feldman 
2201e8db6e2SBrian Feldman 	kex_kexinit_finish(kex);
2211e8db6e2SBrian Feldman }
2221e8db6e2SBrian Feldman 
2231e8db6e2SBrian Feldman Kex *
2241e8db6e2SBrian Feldman kex_setup(char *proposal[PROPOSAL_MAX])
2251e8db6e2SBrian Feldman {
2261e8db6e2SBrian Feldman 	Kex *kex;
2271e8db6e2SBrian Feldman 
228761efaa7SDag-Erling Smørgrav 	kex = xcalloc(1, sizeof(*kex));
2291e8db6e2SBrian Feldman 	buffer_init(&kex->peer);
2301e8db6e2SBrian Feldman 	buffer_init(&kex->my);
2311e8db6e2SBrian Feldman 	kex_prop2buf(&kex->my, proposal);
2321e8db6e2SBrian Feldman 	kex->done = 0;
2331e8db6e2SBrian Feldman 
2341e8db6e2SBrian Feldman 	kex_send_kexinit(kex);					/* we start */
235ae1f160dSDag-Erling Smørgrav 	kex_reset_dispatch();
2361e8db6e2SBrian Feldman 
2371e8db6e2SBrian Feldman 	return kex;
2381e8db6e2SBrian Feldman }
2391e8db6e2SBrian Feldman 
240ae1f160dSDag-Erling Smørgrav static void
2411e8db6e2SBrian Feldman kex_kexinit_finish(Kex *kex)
2421e8db6e2SBrian Feldman {
2431e8db6e2SBrian Feldman 	if (!(kex->flags & KEX_INIT_SENT))
2441e8db6e2SBrian Feldman 		kex_send_kexinit(kex);
2451e8db6e2SBrian Feldman 
2461e8db6e2SBrian Feldman 	kex_choose_conf(kex);
2471e8db6e2SBrian Feldman 
248d0c8c0bcSDag-Erling Smørgrav 	if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
249d0c8c0bcSDag-Erling Smørgrav 	    kex->kex[kex->kex_type] != NULL) {
250d0c8c0bcSDag-Erling Smørgrav 		(kex->kex[kex->kex_type])(kex);
251d0c8c0bcSDag-Erling Smørgrav 	} else {
2521e8db6e2SBrian Feldman 		fatal("Unsupported key exchange %d", kex->kex_type);
253a04a10f8SKris Kennaway 	}
2541e8db6e2SBrian Feldman }
255a04a10f8SKris Kennaway 
256ae1f160dSDag-Erling Smørgrav static void
257a04a10f8SKris Kennaway choose_enc(Enc *enc, char *client, char *server)
258a04a10f8SKris Kennaway {
2591e8db6e2SBrian Feldman 	char *name = match_list(client, server, NULL);
260a04a10f8SKris Kennaway 	if (name == NULL)
261a04a10f8SKris Kennaway 		fatal("no matching cipher found: client %s server %s", client, server);
262ae1f160dSDag-Erling Smørgrav 	if ((enc->cipher = cipher_by_name(name)) == NULL)
2635b9b2fafSBrian Feldman 		fatal("matching cipher is not supported: %s", name);
264a04a10f8SKris Kennaway 	enc->name = name;
265a04a10f8SKris Kennaway 	enc->enabled = 0;
266a04a10f8SKris Kennaway 	enc->iv = NULL;
267a04a10f8SKris Kennaway 	enc->key = NULL;
268ae1f160dSDag-Erling Smørgrav 	enc->key_len = cipher_keylen(enc->cipher);
269ae1f160dSDag-Erling Smørgrav 	enc->block_size = cipher_blocksize(enc->cipher);
270a04a10f8SKris Kennaway }
271761efaa7SDag-Erling Smørgrav 
272ae1f160dSDag-Erling Smørgrav static void
273a04a10f8SKris Kennaway choose_mac(Mac *mac, char *client, char *server)
274a04a10f8SKris Kennaway {
2751e8db6e2SBrian Feldman 	char *name = match_list(client, server, NULL);
276a04a10f8SKris Kennaway 	if (name == NULL)
277a04a10f8SKris Kennaway 		fatal("no matching mac found: client %s server %s", client, server);
2781e8db6e2SBrian Feldman 	if (mac_init(mac, name) < 0)
279a04a10f8SKris Kennaway 		fatal("unsupported mac %s", name);
2801e8db6e2SBrian Feldman 	/* truncate the key */
2811e8db6e2SBrian Feldman 	if (datafellows & SSH_BUG_HMAC)
2821e8db6e2SBrian Feldman 		mac->key_len = 16;
283a04a10f8SKris Kennaway 	mac->name = name;
284a04a10f8SKris Kennaway 	mac->key = NULL;
285a04a10f8SKris Kennaway 	mac->enabled = 0;
286a04a10f8SKris Kennaway }
287761efaa7SDag-Erling Smørgrav 
288ae1f160dSDag-Erling Smørgrav static void
289a04a10f8SKris Kennaway choose_comp(Comp *comp, char *client, char *server)
290a04a10f8SKris Kennaway {
2911e8db6e2SBrian Feldman 	char *name = match_list(client, server, NULL);
292a04a10f8SKris Kennaway 	if (name == NULL)
293a04a10f8SKris Kennaway 		fatal("no matching comp found: client %s server %s", client, server);
294043840dfSDag-Erling Smørgrav 	if (strcmp(name, "zlib@openssh.com") == 0) {
295043840dfSDag-Erling Smørgrav 		comp->type = COMP_DELAYED;
296043840dfSDag-Erling Smørgrav 	} else if (strcmp(name, "zlib") == 0) {
297043840dfSDag-Erling Smørgrav 		comp->type = COMP_ZLIB;
298a04a10f8SKris Kennaway 	} else if (strcmp(name, "none") == 0) {
299043840dfSDag-Erling Smørgrav 		comp->type = COMP_NONE;
300a04a10f8SKris Kennaway 	} else {
301a04a10f8SKris Kennaway 		fatal("unsupported comp %s", name);
302a04a10f8SKris Kennaway 	}
303a04a10f8SKris Kennaway 	comp->name = name;
304a04a10f8SKris Kennaway }
305761efaa7SDag-Erling Smørgrav 
306ae1f160dSDag-Erling Smørgrav static void
307a04a10f8SKris Kennaway choose_kex(Kex *k, char *client, char *server)
308a04a10f8SKris Kennaway {
3091e8db6e2SBrian Feldman 	k->name = match_list(client, server, NULL);
310a04a10f8SKris Kennaway 	if (k->name == NULL)
311a04a10f8SKris Kennaway 		fatal("no kex alg");
3125b9b2fafSBrian Feldman 	if (strcmp(k->name, KEX_DH1) == 0) {
313d0c8c0bcSDag-Erling Smørgrav 		k->kex_type = KEX_DH_GRP1_SHA1;
314021d409fSDag-Erling Smørgrav 		k->evp_md = EVP_sha1();
315d74d50a8SDag-Erling Smørgrav 	} else if (strcmp(k->name, KEX_DH14) == 0) {
316d74d50a8SDag-Erling Smørgrav 		k->kex_type = KEX_DH_GRP14_SHA1;
317021d409fSDag-Erling Smørgrav 		k->evp_md = EVP_sha1();
318021d409fSDag-Erling Smørgrav 	} else if (strcmp(k->name, KEX_DHGEX_SHA1) == 0) {
319d0c8c0bcSDag-Erling Smørgrav 		k->kex_type = KEX_DH_GEX_SHA1;
320021d409fSDag-Erling Smørgrav 		k->evp_md = EVP_sha1();
321761efaa7SDag-Erling Smørgrav #if OPENSSL_VERSION_NUMBER >= 0x00907000L
322761efaa7SDag-Erling Smørgrav 	} else if (strcmp(k->name, KEX_DHGEX_SHA256) == 0) {
323761efaa7SDag-Erling Smørgrav 		k->kex_type = KEX_DH_GEX_SHA256;
324761efaa7SDag-Erling Smørgrav 		k->evp_md = evp_ssh_sha256();
325761efaa7SDag-Erling Smørgrav #endif
3265b9b2fafSBrian Feldman 	} else
327a04a10f8SKris Kennaway 		fatal("bad kex alg %s", k->name);
328a04a10f8SKris Kennaway }
329021d409fSDag-Erling Smørgrav 
330ae1f160dSDag-Erling Smørgrav static void
331a04a10f8SKris Kennaway choose_hostkeyalg(Kex *k, char *client, char *server)
332a04a10f8SKris Kennaway {
3331e8db6e2SBrian Feldman 	char *hostkeyalg = match_list(client, server, NULL);
3341e8db6e2SBrian Feldman 	if (hostkeyalg == NULL)
335a04a10f8SKris Kennaway 		fatal("no hostkey alg");
3361e8db6e2SBrian Feldman 	k->hostkey_type = key_type_from_name(hostkeyalg);
3371e8db6e2SBrian Feldman 	if (k->hostkey_type == KEY_UNSPEC)
3381e8db6e2SBrian Feldman 		fatal("bad hostkey alg '%s'", hostkeyalg);
3391e8db6e2SBrian Feldman 	xfree(hostkeyalg);
340a04a10f8SKris Kennaway }
341a04a10f8SKris Kennaway 
342d0c8c0bcSDag-Erling Smørgrav static int
343d0c8c0bcSDag-Erling Smørgrav proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
344d0c8c0bcSDag-Erling Smørgrav {
345d0c8c0bcSDag-Erling Smørgrav 	static int check[] = {
346d0c8c0bcSDag-Erling Smørgrav 		PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
347d0c8c0bcSDag-Erling Smørgrav 	};
348d0c8c0bcSDag-Erling Smørgrav 	int *idx;
349d0c8c0bcSDag-Erling Smørgrav 	char *p;
350d0c8c0bcSDag-Erling Smørgrav 
351d0c8c0bcSDag-Erling Smørgrav 	for (idx = &check[0]; *idx != -1; idx++) {
352d0c8c0bcSDag-Erling Smørgrav 		if ((p = strchr(my[*idx], ',')) != NULL)
353d0c8c0bcSDag-Erling Smørgrav 			*p = '\0';
354d0c8c0bcSDag-Erling Smørgrav 		if ((p = strchr(peer[*idx], ',')) != NULL)
355d0c8c0bcSDag-Erling Smørgrav 			*p = '\0';
356d0c8c0bcSDag-Erling Smørgrav 		if (strcmp(my[*idx], peer[*idx]) != 0) {
357d0c8c0bcSDag-Erling Smørgrav 			debug2("proposal mismatch: my %s peer %s",
358d0c8c0bcSDag-Erling Smørgrav 			    my[*idx], peer[*idx]);
359d0c8c0bcSDag-Erling Smørgrav 			return (0);
360d0c8c0bcSDag-Erling Smørgrav 		}
361d0c8c0bcSDag-Erling Smørgrav 	}
362d0c8c0bcSDag-Erling Smørgrav 	debug2("proposals match");
363d0c8c0bcSDag-Erling Smørgrav 	return (1);
364d0c8c0bcSDag-Erling Smørgrav }
365d0c8c0bcSDag-Erling Smørgrav 
366ae1f160dSDag-Erling Smørgrav static void
3671e8db6e2SBrian Feldman kex_choose_conf(Kex *kex)
368a04a10f8SKris Kennaway {
3691e8db6e2SBrian Feldman 	Newkeys *newkeys;
3701e8db6e2SBrian Feldman 	char **my, **peer;
3711e8db6e2SBrian Feldman 	char **cprop, **sprop;
3721e8db6e2SBrian Feldman 	int nenc, nmac, ncomp;
373043840dfSDag-Erling Smørgrav 	u_int mode, ctos, need;
374d0c8c0bcSDag-Erling Smørgrav 	int first_kex_follows, type;
375a04a10f8SKris Kennaway 
376d0c8c0bcSDag-Erling Smørgrav 	my   = kex_buf2prop(&kex->my, NULL);
377d0c8c0bcSDag-Erling Smørgrav 	peer = kex_buf2prop(&kex->peer, &first_kex_follows);
378a04a10f8SKris Kennaway 
3791e8db6e2SBrian Feldman 	if (kex->server) {
3801e8db6e2SBrian Feldman 		cprop=peer;
3811e8db6e2SBrian Feldman 		sprop=my;
3821e8db6e2SBrian Feldman 	} else {
3831e8db6e2SBrian Feldman 		cprop=my;
3841e8db6e2SBrian Feldman 		sprop=peer;
3851e8db6e2SBrian Feldman 	}
3861e8db6e2SBrian Feldman 
3871e8db6e2SBrian Feldman 	/* Algorithm Negotiation */
388a04a10f8SKris Kennaway 	for (mode = 0; mode < MODE_MAX; mode++) {
389761efaa7SDag-Erling Smørgrav 		newkeys = xcalloc(1, sizeof(*newkeys));
3901e8db6e2SBrian Feldman 		kex->newkeys[mode] = newkeys;
3911e8db6e2SBrian Feldman 		ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN);
392a04a10f8SKris Kennaway 		nenc  = ctos ? PROPOSAL_ENC_ALGS_CTOS  : PROPOSAL_ENC_ALGS_STOC;
393a04a10f8SKris Kennaway 		nmac  = ctos ? PROPOSAL_MAC_ALGS_CTOS  : PROPOSAL_MAC_ALGS_STOC;
394a04a10f8SKris Kennaway 		ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
3951e8db6e2SBrian Feldman 		choose_enc (&newkeys->enc,  cprop[nenc],  sprop[nenc]);
3961e8db6e2SBrian Feldman 		choose_mac (&newkeys->mac,  cprop[nmac],  sprop[nmac]);
3971e8db6e2SBrian Feldman 		choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
398a04a10f8SKris Kennaway 		debug("kex: %s %s %s %s",
399a04a10f8SKris Kennaway 		    ctos ? "client->server" : "server->client",
4001e8db6e2SBrian Feldman 		    newkeys->enc.name,
4011e8db6e2SBrian Feldman 		    newkeys->mac.name,
4021e8db6e2SBrian Feldman 		    newkeys->comp.name);
403a04a10f8SKris Kennaway 	}
4041e8db6e2SBrian Feldman 	choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
4051e8db6e2SBrian Feldman 	choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
406a04a10f8SKris Kennaway 	    sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
407a04a10f8SKris Kennaway 	need = 0;
408a04a10f8SKris Kennaway 	for (mode = 0; mode < MODE_MAX; mode++) {
4091e8db6e2SBrian Feldman 		newkeys = kex->newkeys[mode];
410ae1f160dSDag-Erling Smørgrav 		if (need < newkeys->enc.key_len)
411ae1f160dSDag-Erling Smørgrav 			need = newkeys->enc.key_len;
412ae1f160dSDag-Erling Smørgrav 		if (need < newkeys->enc.block_size)
413ae1f160dSDag-Erling Smørgrav 			need = newkeys->enc.block_size;
4141e8db6e2SBrian Feldman 		if (need < newkeys->mac.key_len)
4151e8db6e2SBrian Feldman 			need = newkeys->mac.key_len;
416a04a10f8SKris Kennaway 	}
4172632b0c8SKris Kennaway 	/* XXX need runden? */
4181e8db6e2SBrian Feldman 	kex->we_need = need;
4191e8db6e2SBrian Feldman 
420d0c8c0bcSDag-Erling Smørgrav 	/* ignore the next message if the proposals do not match */
421d0c8c0bcSDag-Erling Smørgrav 	if (first_kex_follows && !proposals_match(my, peer) &&
422d0c8c0bcSDag-Erling Smørgrav 	    !(datafellows & SSH_BUG_FIRSTKEX)) {
423d0c8c0bcSDag-Erling Smørgrav 		type = packet_read();
424d0c8c0bcSDag-Erling Smørgrav 		debug2("skipping next packet (type %u)", type);
425d0c8c0bcSDag-Erling Smørgrav 	}
426d0c8c0bcSDag-Erling Smørgrav 
4271e8db6e2SBrian Feldman 	kex_prop_free(my);
4281e8db6e2SBrian Feldman 	kex_prop_free(peer);
429a04a10f8SKris Kennaway }
430a04a10f8SKris Kennaway 
431ae1f160dSDag-Erling Smørgrav static u_char *
432021d409fSDag-Erling Smørgrav derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen,
433021d409fSDag-Erling Smørgrav     BIGNUM *shared_secret)
434a04a10f8SKris Kennaway {
4351e8db6e2SBrian Feldman 	Buffer b;
4361e8db6e2SBrian Feldman 	EVP_MD_CTX md;
4371e8db6e2SBrian Feldman 	char c = id;
438043840dfSDag-Erling Smørgrav 	u_int have;
439021d409fSDag-Erling Smørgrav 	int mdsz;
440043840dfSDag-Erling Smørgrav 	u_char *digest;
441043840dfSDag-Erling Smørgrav 
442021d409fSDag-Erling Smørgrav 	if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0)
443021d409fSDag-Erling Smørgrav 		fatal("bad kex md size %d", mdsz);
444043840dfSDag-Erling Smørgrav 	digest = xmalloc(roundup(need, mdsz));
4451e8db6e2SBrian Feldman 
4461e8db6e2SBrian Feldman 	buffer_init(&b);
4471e8db6e2SBrian Feldman 	buffer_put_bignum2(&b, shared_secret);
4481e8db6e2SBrian Feldman 
4491e8db6e2SBrian Feldman 	/* K1 = HASH(K || H || "A" || session_id) */
450021d409fSDag-Erling Smørgrav 	EVP_DigestInit(&md, kex->evp_md);
451ae1f160dSDag-Erling Smørgrav 	if (!(datafellows & SSH_BUG_DERIVEKEY))
4521e8db6e2SBrian Feldman 		EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
453021d409fSDag-Erling Smørgrav 	EVP_DigestUpdate(&md, hash, hashlen);
4541e8db6e2SBrian Feldman 	EVP_DigestUpdate(&md, &c, 1);
4551e8db6e2SBrian Feldman 	EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
4561e8db6e2SBrian Feldman 	EVP_DigestFinal(&md, digest, NULL);
4571e8db6e2SBrian Feldman 
4581e8db6e2SBrian Feldman 	/*
4591e8db6e2SBrian Feldman 	 * expand key:
4601e8db6e2SBrian Feldman 	 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
4611e8db6e2SBrian Feldman 	 * Key = K1 || K2 || ... || Kn
4621e8db6e2SBrian Feldman 	 */
4631e8db6e2SBrian Feldman 	for (have = mdsz; need > have; have += mdsz) {
464021d409fSDag-Erling Smørgrav 		EVP_DigestInit(&md, kex->evp_md);
465ae1f160dSDag-Erling Smørgrav 		if (!(datafellows & SSH_BUG_DERIVEKEY))
4661e8db6e2SBrian Feldman 			EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
467021d409fSDag-Erling Smørgrav 		EVP_DigestUpdate(&md, hash, hashlen);
4681e8db6e2SBrian Feldman 		EVP_DigestUpdate(&md, digest, have);
4691e8db6e2SBrian Feldman 		EVP_DigestFinal(&md, digest + have, NULL);
4701e8db6e2SBrian Feldman 	}
4711e8db6e2SBrian Feldman 	buffer_free(&b);
4721e8db6e2SBrian Feldman #ifdef DEBUG_KEX
4731e8db6e2SBrian Feldman 	fprintf(stderr, "key '%c'== ", c);
4741e8db6e2SBrian Feldman 	dump_digest("key", digest, need);
4751e8db6e2SBrian Feldman #endif
4761e8db6e2SBrian Feldman 	return digest;
4771e8db6e2SBrian Feldman }
4781e8db6e2SBrian Feldman 
4791e8db6e2SBrian Feldman Newkeys *current_keys[MODE_MAX];
4801e8db6e2SBrian Feldman 
4811e8db6e2SBrian Feldman #define NKEYS	6
4821e8db6e2SBrian Feldman void
483021d409fSDag-Erling Smørgrav kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret)
4841e8db6e2SBrian Feldman {
4851e8db6e2SBrian Feldman 	u_char *keys[NKEYS];
486043840dfSDag-Erling Smørgrav 	u_int i, mode, ctos;
487a04a10f8SKris Kennaway 
488021d409fSDag-Erling Smørgrav 	for (i = 0; i < NKEYS; i++) {
489021d409fSDag-Erling Smørgrav 		keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen,
490021d409fSDag-Erling Smørgrav 		    shared_secret);
491021d409fSDag-Erling Smørgrav 	}
492a04a10f8SKris Kennaway 
493d0c8c0bcSDag-Erling Smørgrav 	debug2("kex_derive_keys");
494a04a10f8SKris Kennaway 	for (mode = 0; mode < MODE_MAX; mode++) {
4951e8db6e2SBrian Feldman 		current_keys[mode] = kex->newkeys[mode];
4961e8db6e2SBrian Feldman 		kex->newkeys[mode] = NULL;
497761efaa7SDag-Erling Smørgrav 		ctos = (!kex->server && mode == MODE_OUT) ||
498761efaa7SDag-Erling Smørgrav 		    (kex->server && mode == MODE_IN);
4991e8db6e2SBrian Feldman 		current_keys[mode]->enc.iv  = keys[ctos ? 0 : 1];
5001e8db6e2SBrian Feldman 		current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
5011e8db6e2SBrian Feldman 		current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
502a04a10f8SKris Kennaway 	}
503a04a10f8SKris Kennaway }
5041e8db6e2SBrian Feldman 
5051e8db6e2SBrian Feldman Newkeys *
5061e8db6e2SBrian Feldman kex_get_newkeys(int mode)
5071e8db6e2SBrian Feldman {
5081e8db6e2SBrian Feldman 	Newkeys *ret;
5091e8db6e2SBrian Feldman 
5101e8db6e2SBrian Feldman 	ret = current_keys[mode];
5111e8db6e2SBrian Feldman 	current_keys[mode] = NULL;
5121e8db6e2SBrian Feldman 	return ret;
5131e8db6e2SBrian Feldman }
5141e8db6e2SBrian Feldman 
515d74d50a8SDag-Erling Smørgrav void
516d74d50a8SDag-Erling Smørgrav derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
517d74d50a8SDag-Erling Smørgrav     u_int8_t cookie[8], u_int8_t id[16])
518d74d50a8SDag-Erling Smørgrav {
519d74d50a8SDag-Erling Smørgrav 	const EVP_MD *evp_md = EVP_md5();
520d74d50a8SDag-Erling Smørgrav 	EVP_MD_CTX md;
521d74d50a8SDag-Erling Smørgrav 	u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE];
522d74d50a8SDag-Erling Smørgrav 	int len;
523d74d50a8SDag-Erling Smørgrav 
524d74d50a8SDag-Erling Smørgrav 	EVP_DigestInit(&md, evp_md);
525d74d50a8SDag-Erling Smørgrav 
526d74d50a8SDag-Erling Smørgrav 	len = BN_num_bytes(host_modulus);
527043840dfSDag-Erling Smørgrav 	if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
528d74d50a8SDag-Erling Smørgrav 		fatal("%s: bad host modulus (len %d)", __func__, len);
529d74d50a8SDag-Erling Smørgrav 	BN_bn2bin(host_modulus, nbuf);
530d74d50a8SDag-Erling Smørgrav 	EVP_DigestUpdate(&md, nbuf, len);
531d74d50a8SDag-Erling Smørgrav 
532d74d50a8SDag-Erling Smørgrav 	len = BN_num_bytes(server_modulus);
533043840dfSDag-Erling Smørgrav 	if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
534d74d50a8SDag-Erling Smørgrav 		fatal("%s: bad server modulus (len %d)", __func__, len);
535d74d50a8SDag-Erling Smørgrav 	BN_bn2bin(server_modulus, nbuf);
536d74d50a8SDag-Erling Smørgrav 	EVP_DigestUpdate(&md, nbuf, len);
537d74d50a8SDag-Erling Smørgrav 
538d74d50a8SDag-Erling Smørgrav 	EVP_DigestUpdate(&md, cookie, 8);
539d74d50a8SDag-Erling Smørgrav 
540d74d50a8SDag-Erling Smørgrav 	EVP_DigestFinal(&md, obuf, NULL);
541d74d50a8SDag-Erling Smørgrav 	memcpy(id, obuf, 16);
542d74d50a8SDag-Erling Smørgrav 
543d74d50a8SDag-Erling Smørgrav 	memset(nbuf, 0, sizeof(nbuf));
544d74d50a8SDag-Erling Smørgrav 	memset(obuf, 0, sizeof(obuf));
545d74d50a8SDag-Erling Smørgrav 	memset(&md, 0, sizeof(md));
546d74d50a8SDag-Erling Smørgrav }
547d74d50a8SDag-Erling Smørgrav 
5481e8db6e2SBrian Feldman #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH)
5491e8db6e2SBrian Feldman void
5501e8db6e2SBrian Feldman dump_digest(char *msg, u_char *digest, int len)
5511e8db6e2SBrian Feldman {
552043840dfSDag-Erling Smørgrav 	u_int i;
5531e8db6e2SBrian Feldman 
5541e8db6e2SBrian Feldman 	fprintf(stderr, "%s\n", msg);
5551e8db6e2SBrian Feldman 	for (i = 0; i< len; i++) {
5561e8db6e2SBrian Feldman 		fprintf(stderr, "%02x", digest[i]);
5571e8db6e2SBrian Feldman 		if (i%32 == 31)
5581e8db6e2SBrian Feldman 			fprintf(stderr, "\n");
5591e8db6e2SBrian Feldman 		else if (i%8 == 7)
5601e8db6e2SBrian Feldman 			fprintf(stderr, " ");
5611e8db6e2SBrian Feldman 	}
5621e8db6e2SBrian Feldman 	fprintf(stderr, "\n");
5631e8db6e2SBrian Feldman }
5641e8db6e2SBrian Feldman #endif
565