blob: 57a79dd9e98ecd710610524a0b0ac40b2c39c407 [file] [log] [blame]
Damien Miller1d75abf2013-01-09 16:12:19 +11001/* $OpenBSD: kex.c,v 1.88 2013/01/08 18:49:04 markus Exp $ */
Damien Millera664e872000-04-16 11:52:47 +10002/*
Ben Lindstrom44697232001-07-04 03:32:30 +00003 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
Damien Millera664e872000-04-16 11:52:47 +10004 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
Damien Millera664e872000-04-16 11:52:47 +100013 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "includes.h"
Damien Millera664e872000-04-16 11:52:47 +100027
Damien Miller8dbffe72006-08-05 11:02:17 +100028#include <sys/param.h>
29
Damien Millerd7834352006-08-05 12:39:39 +100030#include <signal.h>
Damien Millerded319c2006-09-01 15:38:36 +100031#include <stdarg.h>
Damien Millera7a73ee2006-08-05 11:37:59 +100032#include <stdio.h>
Damien Millere7a1e5c2006-08-05 11:34:19 +100033#include <stdlib.h>
Damien Millere3476ed2006-07-24 14:13:33 +100034#include <string.h>
35
Damien Millerd7834352006-08-05 12:39:39 +100036#include <openssl/crypto.h>
37
Ben Lindstrom226cfa02001-01-22 05:34:40 +000038#include "xmalloc.h"
Damien Millerd7834352006-08-05 12:39:39 +100039#include "ssh2.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000040#include "buffer.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000041#include "packet.h"
42#include "compat.h"
43#include "cipher.h"
Damien Miller0bc1bd82000-11-13 22:57:25 +110044#include "key.h"
Damien Millerd7834352006-08-05 12:39:39 +100045#include "kex.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000046#include "log.h"
Ben Lindstrom06b33aa2001-02-15 03:01:59 +000047#include "mac.h"
Ben Lindstromb9be60a2001-03-11 01:49:19 +000048#include "match.h"
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +000049#include "dispatch.h"
Ben Lindstrom7a2073c2002-03-22 02:30:41 +000050#include "monitor.h"
Darren Tucker36331b52010-01-08 16:50:41 +110051#include "roaming.h"
Damien Millera664e872000-04-16 11:52:47 +100052
Damien Millerb3092032006-03-16 18:22:18 +110053#if OPENSSL_VERSION_NUMBER >= 0x00907000L
54# if defined(HAVE_EVP_SHA256)
Damien Milleraf87af12006-03-15 13:02:28 +110055# define evp_ssh_sha256 EVP_sha256
Damien Millerb3092032006-03-16 18:22:18 +110056# else
Damien Millera63128d2006-03-15 12:08:28 +110057extern const EVP_MD *evp_ssh_sha256(void);
Damien Millerb3092032006-03-16 18:22:18 +110058# endif
Tim Rice425a6882006-03-15 20:17:05 -080059#endif
Damien Millera63128d2006-03-15 12:08:28 +110060
Ben Lindstrombba81212001-06-25 05:01:22 +000061/* prototype */
62static void kex_kexinit_finish(Kex *);
63static void kex_choose_conf(Kex *);
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +000064
Damien Millerd5f62bf2010-09-24 22:11:14 +100065/* Validate KEX method name list */
66int
67kex_names_valid(const char *names)
68{
69 char *s, *cp, *p;
70
71 if (names == NULL || strcmp(names, "") == 0)
72 return 0;
73 s = cp = xstrdup(names);
74 for ((p = strsep(&cp, ",")); p && *p != '\0';
75 (p = strsep(&cp, ","))) {
76 if (strcmp(p, KEX_DHGEX_SHA256) != 0 &&
77 strcmp(p, KEX_DHGEX_SHA1) != 0 &&
78 strcmp(p, KEX_DH14) != 0 &&
79 strcmp(p, KEX_DH1) != 0 &&
80 (strncmp(p, KEX_ECDH_SHA2_STEM,
81 sizeof(KEX_ECDH_SHA2_STEM) - 1) != 0 ||
82 kex_ecdh_name_to_nid(p) == -1)) {
83 error("Unsupported KEX algorithm \"%.100s\"", p);
84 xfree(s);
85 return 0;
86 }
87 }
88 debug3("kex names ok: [%s]", names);
89 xfree(s);
90 return 1;
91}
92
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +000093/* put algorithm proposal into buffer */
Ben Lindstrombba81212001-06-25 05:01:22 +000094static void
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +000095kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
Damien Millera664e872000-04-16 11:52:47 +100096{
Damien Millereccb9de2005-06-17 12:59:34 +100097 u_int i;
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +000098
99 buffer_clear(b);
Ben Lindstrom59971722002-03-27 17:42:57 +0000100 /*
101 * add a dummy cookie, the cookie will be overwritten by
102 * kex_send_kexinit(), each time a kexinit is set
103 */
104 for (i = 0; i < KEX_COOKIE_LEN; i++)
105 buffer_put_char(b, 0);
Damien Millera664e872000-04-16 11:52:47 +1000106 for (i = 0; i < PROPOSAL_MAX; i++)
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000107 buffer_put_cstring(b, proposal[i]);
108 buffer_put_char(b, 0); /* first_kex_packet_follows */
109 buffer_put_int(b, 0); /* uint32 reserved */
Damien Millera664e872000-04-16 11:52:47 +1000110}
111
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000112/* parse buffer and return algorithm proposal */
Ben Lindstrombba81212001-06-25 05:01:22 +0000113static char **
Damien Millerbabb47a2003-02-24 11:53:32 +1100114kex_buf2prop(Buffer *raw, int *first_kex_follows)
Damien Millerb1715dc2000-05-30 13:44:51 +1000115{
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000116 Buffer b;
Darren Tucker0d0d1952007-06-05 18:23:28 +1000117 u_int i;
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000118 char **proposal;
Damien Millerb1715dc2000-05-30 13:44:51 +1000119
Damien Miller07d86be2006-03-26 14:19:21 +1100120 proposal = xcalloc(PROPOSAL_MAX, sizeof(char *));
Damien Millerb1715dc2000-05-30 13:44:51 +1000121
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000122 buffer_init(&b);
123 buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
Damien Millerb1715dc2000-05-30 13:44:51 +1000124 /* skip cookie */
125 for (i = 0; i < KEX_COOKIE_LEN; i++)
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000126 buffer_get_char(&b);
Damien Millerb1715dc2000-05-30 13:44:51 +1000127 /* extract kex init proposal strings */
128 for (i = 0; i < PROPOSAL_MAX; i++) {
Damien Millerda108ec2010-08-31 22:36:39 +1000129 proposal[i] = buffer_get_cstring(&b,NULL);
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000130 debug2("kex_parse_kexinit: %s", proposal[i]);
Damien Millerb1715dc2000-05-30 13:44:51 +1000131 }
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000132 /* first kex follows / reserved */
133 i = buffer_get_char(&b);
Damien Millerbabb47a2003-02-24 11:53:32 +1100134 if (first_kex_follows != NULL)
135 *first_kex_follows = i;
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000136 debug2("kex_parse_kexinit: first_kex_follows %d ", i);
137 i = buffer_get_int(&b);
Darren Tucker0d0d1952007-06-05 18:23:28 +1000138 debug2("kex_parse_kexinit: reserved %u ", i);
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000139 buffer_free(&b);
140 return proposal;
Damien Millerb1715dc2000-05-30 13:44:51 +1000141}
142
Ben Lindstrombba81212001-06-25 05:01:22 +0000143static void
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000144kex_prop_free(char **proposal)
Damien Millera664e872000-04-16 11:52:47 +1000145{
Damien Millereccb9de2005-06-17 12:59:34 +1000146 u_int i;
Damien Millera664e872000-04-16 11:52:47 +1000147
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000148 for (i = 0; i < PROPOSAL_MAX; i++)
149 xfree(proposal[i]);
150 xfree(proposal);
Damien Millera664e872000-04-16 11:52:47 +1000151}
152
Darren Tucker0d0d1952007-06-05 18:23:28 +1000153/* ARGSUSED */
Ben Lindstrombba81212001-06-25 05:01:22 +0000154static void
Damien Miller630d6f42002-01-22 23:17:30 +1100155kex_protocol_error(int type, u_int32_t seq, void *ctxt)
Damien Miller874d77b2000-10-14 16:23:11 +1100156{
Damien Miller630d6f42002-01-22 23:17:30 +1100157 error("Hm, kex protocol error: type %d seq %u", type, seq);
Damien Miller874d77b2000-10-14 16:23:11 +1100158}
159
Ben Lindstrombba81212001-06-25 05:01:22 +0000160static void
Damien Millerbc27d4e2002-02-13 13:54:06 +1100161kex_reset_dispatch(void)
Ben Lindstrom8ac91062001-04-04 17:57:54 +0000162{
Damien Miller7d053392002-01-22 23:24:13 +1100163 dispatch_range(SSH2_MSG_TRANSPORT_MIN,
164 SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
Damien Millerbc27d4e2002-02-13 13:54:06 +1100165 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
Ben Lindstrom8ac91062001-04-04 17:57:54 +0000166}
167
168void
Ben Lindstrom238abf62001-04-04 17:52:53 +0000169kex_finish(Kex *kex)
Damien Millera664e872000-04-16 11:52:47 +1000170{
Damien Millerbc27d4e2002-02-13 13:54:06 +1100171 kex_reset_dispatch();
Ben Lindstrom238abf62001-04-04 17:52:53 +0000172
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000173 packet_start(SSH2_MSG_NEWKEYS);
174 packet_send();
175 /* packet_write_wait(); */
176 debug("SSH2_MSG_NEWKEYS sent");
Damien Millera664e872000-04-16 11:52:47 +1000177
Ben Lindstrom064496f2002-12-23 02:04:22 +0000178 debug("expecting SSH2_MSG_NEWKEYS");
Damien Millerdff50992002-01-22 23:16:32 +1100179 packet_read_expect(SSH2_MSG_NEWKEYS);
Ben Lindstrom14519082002-02-26 17:58:29 +0000180 packet_check_eom();
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000181 debug("SSH2_MSG_NEWKEYS received");
Ben Lindstrom5ba23b32001-04-05 02:05:21 +0000182
Ben Lindstrombe2cc432001-04-04 23:46:07 +0000183 kex->done = 1;
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000184 buffer_clear(&kex->peer);
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000185 /* buffer_clear(&kex->my); */
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000186 kex->flags &= ~KEX_INIT_SENT;
Ben Lindstrom5ba23b32001-04-05 02:05:21 +0000187 xfree(kex->name);
188 kex->name = NULL;
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000189}
Damien Millera664e872000-04-16 11:52:47 +1000190
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000191void
192kex_send_kexinit(Kex *kex)
193{
Darren Tucker3f9fdc72004-06-22 12:56:01 +1000194 u_int32_t rnd = 0;
Ben Lindstrom59971722002-03-27 17:42:57 +0000195 u_char *cookie;
Damien Millereccb9de2005-06-17 12:59:34 +1000196 u_int i;
Ben Lindstrom59971722002-03-27 17:42:57 +0000197
Ben Lindstrom8ac91062001-04-04 17:57:54 +0000198 if (kex == NULL) {
199 error("kex_send_kexinit: no kex, cannot rekey");
200 return;
201 }
Ben Lindstrom238abf62001-04-04 17:52:53 +0000202 if (kex->flags & KEX_INIT_SENT) {
203 debug("KEX_INIT_SENT");
204 return;
205 }
Ben Lindstrombe2cc432001-04-04 23:46:07 +0000206 kex->done = 0;
Ben Lindstrom59971722002-03-27 17:42:57 +0000207
208 /* generate a random cookie */
209 if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
210 fatal("kex_send_kexinit: kex proposal too short");
211 cookie = buffer_ptr(&kex->my);
212 for (i = 0; i < KEX_COOKIE_LEN; i++) {
213 if (i % 4 == 0)
Darren Tucker3f9fdc72004-06-22 12:56:01 +1000214 rnd = arc4random();
215 cookie[i] = rnd;
216 rnd >>= 8;
Ben Lindstrom59971722002-03-27 17:42:57 +0000217 }
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000218 packet_start(SSH2_MSG_KEXINIT);
219 packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
220 packet_send();
221 debug("SSH2_MSG_KEXINIT sent");
222 kex->flags |= KEX_INIT_SENT;
223}
224
Darren Tucker0d0d1952007-06-05 18:23:28 +1000225/* ARGSUSED */
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000226void
Damien Miller630d6f42002-01-22 23:17:30 +1100227kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000228{
229 char *ptr;
Damien Millereccb9de2005-06-17 12:59:34 +1000230 u_int i, dlen;
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000231 Kex *kex = (Kex *)ctxt;
232
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000233 debug("SSH2_MSG_KEXINIT received");
Ben Lindstrom8ac91062001-04-04 17:57:54 +0000234 if (kex == NULL)
235 fatal("kex_input_kexinit: no kex, cannot rekey");
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000236
237 ptr = packet_get_raw(&dlen);
238 buffer_append(&kex->peer, ptr, dlen);
239
Ben Lindstrom8e312f32001-04-04 23:50:21 +0000240 /* discard packet */
241 for (i = 0; i < KEX_COOKIE_LEN; i++)
242 packet_get_char();
243 for (i = 0; i < PROPOSAL_MAX; i++)
244 xfree(packet_get_string(NULL));
Darren Tuckerae608bd2012-09-06 21:19:51 +1000245 /*
246 * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
247 * KEX method has the server move first, but a server might be using
248 * a custom method or one that we otherwise don't support. We should
249 * be prepared to remember first_kex_follows here so we can eat a
250 * packet later.
251 * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
252 * for cases where the server *doesn't* go first. I guess we should
253 * ignore it when it is set for these cases, which is what we do now.
254 */
255 (void) packet_get_char(); /* first_kex_follows */
256 (void) packet_get_int(); /* reserved */
Damien Miller48b03fc2002-01-22 23:11:40 +1100257 packet_check_eom();
Ben Lindstrom8e312f32001-04-04 23:50:21 +0000258
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000259 kex_kexinit_finish(kex);
260}
261
262Kex *
Ben Lindstrom238abf62001-04-04 17:52:53 +0000263kex_setup(char *proposal[PROPOSAL_MAX])
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000264{
265 Kex *kex;
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000266
Damien Miller07d86be2006-03-26 14:19:21 +1100267 kex = xcalloc(1, sizeof(*kex));
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000268 buffer_init(&kex->peer);
269 buffer_init(&kex->my);
270 kex_prop2buf(&kex->my, proposal);
Ben Lindstrombe2cc432001-04-04 23:46:07 +0000271 kex->done = 0;
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000272
273 kex_send_kexinit(kex); /* we start */
Damien Millerbc27d4e2002-02-13 13:54:06 +1100274 kex_reset_dispatch();
Ben Lindstrom8ac91062001-04-04 17:57:54 +0000275
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000276 return kex;
277}
278
Ben Lindstrombba81212001-06-25 05:01:22 +0000279static void
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000280kex_kexinit_finish(Kex *kex)
281{
282 if (!(kex->flags & KEX_INIT_SENT))
283 kex_send_kexinit(kex);
284
285 kex_choose_conf(kex);
286
Damien Miller8e7fb332003-02-24 12:03:03 +1100287 if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
288 kex->kex[kex->kex_type] != NULL) {
289 (kex->kex[kex->kex_type])(kex);
290 } else {
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000291 fatal("Unsupported key exchange %d", kex->kex_type);
Damien Millera664e872000-04-16 11:52:47 +1000292 }
Damien Millera664e872000-04-16 11:52:47 +1000293}
294
Ben Lindstrombba81212001-06-25 05:01:22 +0000295static void
Damien Millera664e872000-04-16 11:52:47 +1000296choose_enc(Enc *enc, char *client, char *server)
297{
Ben Lindstromb9be60a2001-03-11 01:49:19 +0000298 char *name = match_list(client, server, NULL);
Damien Millera664e872000-04-16 11:52:47 +1000299 if (name == NULL)
Darren Tucker0d0d1952007-06-05 18:23:28 +1000300 fatal("no matching cipher found: client %s server %s",
301 client, server);
Damien Miller963f6b22002-02-19 15:21:23 +1100302 if ((enc->cipher = cipher_by_name(name)) == NULL)
Damien Miller874d77b2000-10-14 16:23:11 +1100303 fatal("matching cipher is not supported: %s", name);
Damien Millera664e872000-04-16 11:52:47 +1000304 enc->name = name;
305 enc->enabled = 0;
306 enc->iv = NULL;
Damien Miller1d75abf2013-01-09 16:12:19 +1100307 enc->iv_len = cipher_ivlen(enc->cipher);
Damien Millera664e872000-04-16 11:52:47 +1000308 enc->key = NULL;
Damien Miller963f6b22002-02-19 15:21:23 +1100309 enc->key_len = cipher_keylen(enc->cipher);
310 enc->block_size = cipher_blocksize(enc->cipher);
Damien Millera664e872000-04-16 11:52:47 +1000311}
Damien Miller4f7becb2006-03-26 14:10:14 +1100312
Ben Lindstrombba81212001-06-25 05:01:22 +0000313static void
Damien Millera664e872000-04-16 11:52:47 +1000314choose_mac(Mac *mac, char *client, char *server)
315{
Ben Lindstromb9be60a2001-03-11 01:49:19 +0000316 char *name = match_list(client, server, NULL);
Damien Millera664e872000-04-16 11:52:47 +1000317 if (name == NULL)
Darren Tucker0d0d1952007-06-05 18:23:28 +1000318 fatal("no matching mac found: client %s server %s",
319 client, server);
Darren Tucker5f3d5be2007-06-05 18:30:18 +1000320 if (mac_setup(mac, name) < 0)
Damien Millera664e872000-04-16 11:52:47 +1000321 fatal("unsupported mac %s", name);
Ben Lindstrom06b33aa2001-02-15 03:01:59 +0000322 /* truncate the key */
323 if (datafellows & SSH_BUG_HMAC)
324 mac->key_len = 16;
Damien Millera664e872000-04-16 11:52:47 +1000325 mac->name = name;
Damien Millera664e872000-04-16 11:52:47 +1000326 mac->key = NULL;
327 mac->enabled = 0;
328}
Damien Miller4f7becb2006-03-26 14:10:14 +1100329
Ben Lindstrombba81212001-06-25 05:01:22 +0000330static void
Damien Millera664e872000-04-16 11:52:47 +1000331choose_comp(Comp *comp, char *client, char *server)
332{
Ben Lindstromb9be60a2001-03-11 01:49:19 +0000333 char *name = match_list(client, server, NULL);
Damien Millera664e872000-04-16 11:52:47 +1000334 if (name == NULL)
335 fatal("no matching comp found: client %s server %s", client, server);
Damien Miller9786e6e2005-07-26 21:54:56 +1000336 if (strcmp(name, "zlib@openssh.com") == 0) {
337 comp->type = COMP_DELAYED;
338 } else if (strcmp(name, "zlib") == 0) {
339 comp->type = COMP_ZLIB;
Damien Millera664e872000-04-16 11:52:47 +1000340 } else if (strcmp(name, "none") == 0) {
Damien Miller9786e6e2005-07-26 21:54:56 +1000341 comp->type = COMP_NONE;
Damien Millera664e872000-04-16 11:52:47 +1000342 } else {
343 fatal("unsupported comp %s", name);
344 }
345 comp->name = name;
346}
Damien Miller4f7becb2006-03-26 14:10:14 +1100347
Ben Lindstrombba81212001-06-25 05:01:22 +0000348static void
Damien Millera664e872000-04-16 11:52:47 +1000349choose_kex(Kex *k, char *client, char *server)
350{
Ben Lindstromb9be60a2001-03-11 01:49:19 +0000351 k->name = match_list(client, server, NULL);
Damien Millera664e872000-04-16 11:52:47 +1000352 if (k->name == NULL)
Darren Tucker0d0d1952007-06-05 18:23:28 +1000353 fatal("Unable to negotiate a key exchange method");
Damien Miller874d77b2000-10-14 16:23:11 +1100354 if (strcmp(k->name, KEX_DH1) == 0) {
Damien Miller8e7fb332003-02-24 12:03:03 +1100355 k->kex_type = KEX_DH_GRP1_SHA1;
Damien Miller19bb3a52005-11-05 15:19:35 +1100356 k->evp_md = EVP_sha1();
Damien Millerf675fc42004-06-15 10:30:09 +1000357 } else if (strcmp(k->name, KEX_DH14) == 0) {
358 k->kex_type = KEX_DH_GRP14_SHA1;
Damien Miller19bb3a52005-11-05 15:19:35 +1100359 k->evp_md = EVP_sha1();
360 } else if (strcmp(k->name, KEX_DHGEX_SHA1) == 0) {
Damien Miller8e7fb332003-02-24 12:03:03 +1100361 k->kex_type = KEX_DH_GEX_SHA1;
Damien Miller19bb3a52005-11-05 15:19:35 +1100362 k->evp_md = EVP_sha1();
Damien Millerb3092032006-03-16 18:22:18 +1100363#if OPENSSL_VERSION_NUMBER >= 0x00907000L
Damien Millera63128d2006-03-15 12:08:28 +1100364 } else if (strcmp(k->name, KEX_DHGEX_SHA256) == 0) {
365 k->kex_type = KEX_DH_GEX_SHA256;
366 k->evp_md = evp_ssh_sha256();
Damien Miller041ab7c2010-09-10 11:23:34 +1000367 } else if (strncmp(k->name, KEX_ECDH_SHA2_STEM,
368 sizeof(KEX_ECDH_SHA2_STEM) - 1) == 0) {
369 k->kex_type = KEX_ECDH_SHA2;
370 k->evp_md = kex_ecdh_name_to_evpmd(k->name);
Damien Millerb3092032006-03-16 18:22:18 +1100371#endif
Damien Miller874d77b2000-10-14 16:23:11 +1100372 } else
Damien Millera664e872000-04-16 11:52:47 +1000373 fatal("bad kex alg %s", k->name);
374}
Damien Miller19bb3a52005-11-05 15:19:35 +1100375
Ben Lindstrombba81212001-06-25 05:01:22 +0000376static void
Damien Millera664e872000-04-16 11:52:47 +1000377choose_hostkeyalg(Kex *k, char *client, char *server)
378{
Ben Lindstromb9be60a2001-03-11 01:49:19 +0000379 char *hostkeyalg = match_list(client, server, NULL);
Damien Miller0bc1bd82000-11-13 22:57:25 +1100380 if (hostkeyalg == NULL)
Damien Millera664e872000-04-16 11:52:47 +1000381 fatal("no hostkey alg");
Damien Miller0bc1bd82000-11-13 22:57:25 +1100382 k->hostkey_type = key_type_from_name(hostkeyalg);
383 if (k->hostkey_type == KEY_UNSPEC)
384 fatal("bad hostkey alg '%s'", hostkeyalg);
Ben Lindstrom48bd7c12001-01-09 00:35:42 +0000385 xfree(hostkeyalg);
Damien Millera664e872000-04-16 11:52:47 +1000386}
387
Damien Millera8e06ce2003-11-21 23:48:55 +1100388static int
Damien Millerbabb47a2003-02-24 11:53:32 +1100389proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
390{
391 static int check[] = {
392 PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
393 };
394 int *idx;
395 char *p;
396
397 for (idx = &check[0]; *idx != -1; idx++) {
398 if ((p = strchr(my[*idx], ',')) != NULL)
399 *p = '\0';
400 if ((p = strchr(peer[*idx], ',')) != NULL)
401 *p = '\0';
402 if (strcmp(my[*idx], peer[*idx]) != 0) {
403 debug2("proposal mismatch: my %s peer %s",
404 my[*idx], peer[*idx]);
405 return (0);
406 }
407 }
408 debug2("proposals match");
409 return (1);
410}
411
Ben Lindstrombba81212001-06-25 05:01:22 +0000412static void
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000413kex_choose_conf(Kex *kex)
Damien Millera664e872000-04-16 11:52:47 +1000414{
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000415 Newkeys *newkeys;
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000416 char **my, **peer;
417 char **cprop, **sprop;
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000418 int nenc, nmac, ncomp;
Damien Miller1d75abf2013-01-09 16:12:19 +1100419 u_int mode, ctos, need, authlen;
Damien Millerbabb47a2003-02-24 11:53:32 +1100420 int first_kex_follows, type;
Damien Millera664e872000-04-16 11:52:47 +1000421
Damien Millerbabb47a2003-02-24 11:53:32 +1100422 my = kex_buf2prop(&kex->my, NULL);
423 peer = kex_buf2prop(&kex->peer, &first_kex_follows);
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000424
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000425 if (kex->server) {
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000426 cprop=peer;
427 sprop=my;
428 } else {
429 cprop=my;
430 sprop=peer;
431 }
Damien Millera664e872000-04-16 11:52:47 +1000432
Darren Tucker36331b52010-01-08 16:50:41 +1100433 /* Check whether server offers roaming */
434 if (!kex->server) {
435 char *roaming;
436 roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL);
437 if (roaming) {
438 kex->roaming = 1;
439 xfree(roaming);
440 }
441 }
442
Ben Lindstrombe2cc432001-04-04 23:46:07 +0000443 /* Algorithm Negotiation */
Damien Millera664e872000-04-16 11:52:47 +1000444 for (mode = 0; mode < MODE_MAX; mode++) {
Damien Miller07d86be2006-03-26 14:19:21 +1100445 newkeys = xcalloc(1, sizeof(*newkeys));
Ben Lindstrombe2cc432001-04-04 23:46:07 +0000446 kex->newkeys[mode] = newkeys;
Darren Tucker0d0d1952007-06-05 18:23:28 +1000447 ctos = (!kex->server && mode == MODE_OUT) ||
448 (kex->server && mode == MODE_IN);
Damien Millera664e872000-04-16 11:52:47 +1000449 nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
450 nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
451 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
Damien Miller1d75abf2013-01-09 16:12:19 +1100452 choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]);
453 /* ignore mac for authenticated encryption */
454 authlen = cipher_authlen(newkeys->enc.cipher);
455 if (authlen == 0)
456 choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]);
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000457 choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
Damien Millera664e872000-04-16 11:52:47 +1000458 debug("kex: %s %s %s %s",
459 ctos ? "client->server" : "server->client",
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000460 newkeys->enc.name,
Damien Miller1d75abf2013-01-09 16:12:19 +1100461 authlen == 0 ? newkeys->mac.name : "<implicit>",
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000462 newkeys->comp.name);
Damien Millera664e872000-04-16 11:52:47 +1000463 }
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000464 choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
465 choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
Damien Millera664e872000-04-16 11:52:47 +1000466 sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
Damien Millera664e872000-04-16 11:52:47 +1000467 need = 0;
468 for (mode = 0; mode < MODE_MAX; mode++) {
Ben Lindstrombe2cc432001-04-04 23:46:07 +0000469 newkeys = kex->newkeys[mode];
Damien Miller963f6b22002-02-19 15:21:23 +1100470 if (need < newkeys->enc.key_len)
471 need = newkeys->enc.key_len;
472 if (need < newkeys->enc.block_size)
473 need = newkeys->enc.block_size;
Damien Miller1d75abf2013-01-09 16:12:19 +1100474 if (need < newkeys->enc.iv_len)
475 need = newkeys->enc.iv_len;
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000476 if (need < newkeys->mac.key_len)
477 need = newkeys->mac.key_len;
Damien Millera664e872000-04-16 11:52:47 +1000478 }
Damien Millerb1715dc2000-05-30 13:44:51 +1000479 /* XXX need runden? */
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000480 kex->we_need = need;
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000481
Damien Millerbabb47a2003-02-24 11:53:32 +1100482 /* ignore the next message if the proposals do not match */
Damien Millera8e06ce2003-11-21 23:48:55 +1100483 if (first_kex_follows && !proposals_match(my, peer) &&
Damien Miller0dc1bef2005-07-17 17:22:45 +1000484 !(datafellows & SSH_BUG_FIRSTKEX)) {
Damien Millerbabb47a2003-02-24 11:53:32 +1100485 type = packet_read();
486 debug2("skipping next packet (type %u)", type);
487 }
488
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000489 kex_prop_free(my);
490 kex_prop_free(peer);
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000491}
492
Ben Lindstrombba81212001-06-25 05:01:22 +0000493static u_char *
Damien Miller19bb3a52005-11-05 15:19:35 +1100494derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen,
495 BIGNUM *shared_secret)
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000496{
497 Buffer b;
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000498 EVP_MD_CTX md;
499 char c = id;
Damien Millereccb9de2005-06-17 12:59:34 +1000500 u_int have;
Damien Miller19bb3a52005-11-05 15:19:35 +1100501 int mdsz;
Damien Millereccb9de2005-06-17 12:59:34 +1000502 u_char *digest;
Damien Miller46d38de2005-07-17 17:02:09 +1000503
Damien Miller19bb3a52005-11-05 15:19:35 +1100504 if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0)
505 fatal("bad kex md size %d", mdsz);
Damien Millerc91e5562006-03-26 13:58:55 +1100506 digest = xmalloc(roundup(need, mdsz));
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000507
508 buffer_init(&b);
509 buffer_put_bignum2(&b, shared_secret);
510
Ben Lindstrombe2cc432001-04-04 23:46:07 +0000511 /* K1 = HASH(K || H || "A" || session_id) */
Damien Miller19bb3a52005-11-05 15:19:35 +1100512 EVP_DigestInit(&md, kex->evp_md);
Ben Lindstrom8c963922001-04-30 23:06:57 +0000513 if (!(datafellows & SSH_BUG_DERIVEKEY))
514 EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
Damien Miller19bb3a52005-11-05 15:19:35 +1100515 EVP_DigestUpdate(&md, hash, hashlen);
Ben Lindstrombe2cc432001-04-04 23:46:07 +0000516 EVP_DigestUpdate(&md, &c, 1);
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000517 EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000518 EVP_DigestFinal(&md, digest, NULL);
519
Ben Lindstrombe2cc432001-04-04 23:46:07 +0000520 /*
521 * expand key:
522 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
523 * Key = K1 || K2 || ... || Kn
524 */
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000525 for (have = mdsz; need > have; have += mdsz) {
Damien Miller19bb3a52005-11-05 15:19:35 +1100526 EVP_DigestInit(&md, kex->evp_md);
Ben Lindstrom8c963922001-04-30 23:06:57 +0000527 if (!(datafellows & SSH_BUG_DERIVEKEY))
528 EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
Damien Miller19bb3a52005-11-05 15:19:35 +1100529 EVP_DigestUpdate(&md, hash, hashlen);
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000530 EVP_DigestUpdate(&md, digest, have);
531 EVP_DigestFinal(&md, digest + have, NULL);
532 }
533 buffer_free(&b);
534#ifdef DEBUG_KEX
535 fprintf(stderr, "key '%c'== ", c);
536 dump_digest("key", digest, need);
537#endif
538 return digest;
Damien Millera664e872000-04-16 11:52:47 +1000539}
540
Ben Lindstrombe2cc432001-04-04 23:46:07 +0000541Newkeys *current_keys[MODE_MAX];
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000542
Ben Lindstromb9be60a2001-03-11 01:49:19 +0000543#define NKEYS 6
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000544void
Damien Miller19bb3a52005-11-05 15:19:35 +1100545kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret)
Damien Millera664e872000-04-16 11:52:47 +1000546{
Ben Lindstrom46c16222000-12-22 01:43:59 +0000547 u_char *keys[NKEYS];
Damien Millereccb9de2005-06-17 12:59:34 +1000548 u_int i, mode, ctos;
Damien Millera664e872000-04-16 11:52:47 +1000549
Damien Miller19bb3a52005-11-05 15:19:35 +1100550 for (i = 0; i < NKEYS; i++) {
551 keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen,
552 shared_secret);
553 }
Damien Millera664e872000-04-16 11:52:47 +1000554
Ben Lindstrom064496f2002-12-23 02:04:22 +0000555 debug2("kex_derive_keys");
Damien Millera664e872000-04-16 11:52:47 +1000556 for (mode = 0; mode < MODE_MAX; mode++) {
Ben Lindstrombe2cc432001-04-04 23:46:07 +0000557 current_keys[mode] = kex->newkeys[mode];
558 kex->newkeys[mode] = NULL;
Damien Miller4f7becb2006-03-26 14:10:14 +1100559 ctos = (!kex->server && mode == MODE_OUT) ||
560 (kex->server && mode == MODE_IN);
Ben Lindstrombe2cc432001-04-04 23:46:07 +0000561 current_keys[mode]->enc.iv = keys[ctos ? 0 : 1];
562 current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
563 current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
Damien Millera664e872000-04-16 11:52:47 +1000564 }
Damien Millera664e872000-04-16 11:52:47 +1000565}
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000566
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000567Newkeys *
568kex_get_newkeys(int mode)
569{
Ben Lindstrombe2cc432001-04-04 23:46:07 +0000570 Newkeys *ret;
571
572 ret = current_keys[mode];
573 current_keys[mode] = NULL;
574 return ret;
Ben Lindstrom2d90e002001-04-04 02:00:54 +0000575}
576
Darren Tuckere14e0052004-05-13 16:30:44 +1000577void
578derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
579 u_int8_t cookie[8], u_int8_t id[16])
580{
581 const EVP_MD *evp_md = EVP_md5();
582 EVP_MD_CTX md;
583 u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE];
584 int len;
585
586 EVP_DigestInit(&md, evp_md);
587
588 len = BN_num_bytes(host_modulus);
Damien Millereccb9de2005-06-17 12:59:34 +1000589 if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
Darren Tuckere14e0052004-05-13 16:30:44 +1000590 fatal("%s: bad host modulus (len %d)", __func__, len);
591 BN_bn2bin(host_modulus, nbuf);
592 EVP_DigestUpdate(&md, nbuf, len);
593
594 len = BN_num_bytes(server_modulus);
Damien Millereccb9de2005-06-17 12:59:34 +1000595 if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
Darren Tuckere14e0052004-05-13 16:30:44 +1000596 fatal("%s: bad server modulus (len %d)", __func__, len);
597 BN_bn2bin(server_modulus, nbuf);
598 EVP_DigestUpdate(&md, nbuf, len);
599
600 EVP_DigestUpdate(&md, cookie, 8);
601
Darren Tuckerb42714e2004-05-13 16:31:48 +1000602 EVP_DigestFinal(&md, obuf, NULL);
Darren Tuckere14e0052004-05-13 16:30:44 +1000603 memcpy(id, obuf, 16);
604
605 memset(nbuf, 0, sizeof(nbuf));
606 memset(obuf, 0, sizeof(obuf));
607 memset(&md, 0, sizeof(md));
608}
609
Damien Millereb8b60e2010-08-31 22:41:14 +1000610#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000611void
612dump_digest(char *msg, u_char *digest, int len)
613{
Damien Millereb8b60e2010-08-31 22:41:14 +1000614 int i;
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000615
616 fprintf(stderr, "%s\n", msg);
Darren Tucker82a3d2b2007-02-19 22:10:25 +1100617 for (i = 0; i < len; i++) {
Ben Lindstrom20d7c7b2001-04-04 01:56:17 +0000618 fprintf(stderr, "%02x", digest[i]);
619 if (i%32 == 31)
620 fprintf(stderr, "\n");
621 else if (i%8 == 7)
622 fprintf(stderr, " ");
623 }
624 fprintf(stderr, "\n");
625}
626#endif