1 /* $OpenBSD: kex.c,v 1.98 2014/02/02 03:44:31 djm Exp $ */
2 /* $FreeBSD$ */
3 /*
4 * Copyright (c) 2000, 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"
28
29 #include <sys/param.h>
30
31 #include <signal.h>
32 #include <stdarg.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <string.h>
36
37 #include <openssl/crypto.h>
38
39 #include "xmalloc.h"
40 #include "ssh2.h"
41 #include "buffer.h"
42 #include "packet.h"
43 #include "compat.h"
44 #include "cipher.h"
45 #include "key.h"
46 #include "kex.h"
47 #include "log.h"
48 #include "mac.h"
49 #include "match.h"
50 #include "dispatch.h"
51 #include "monitor.h"
52 #include "roaming.h"
53 #include "digest.h"
54
55 #if OPENSSL_VERSION_NUMBER >= 0x00907000L
56 # if defined(HAVE_EVP_SHA256)
57 # define evp_ssh_sha256 EVP_sha256
58 # else
59 extern const EVP_MD *evp_ssh_sha256(void);
60 # endif
61 #endif
62
63 /* prototype */
64 static void kex_kexinit_finish(Kex *);
65 static void kex_choose_conf(Kex *);
66
67 struct kexalg {
68 char *name;
69 int type;
70 int ec_nid;
71 int hash_alg;
72 };
73 static const struct kexalg kexalgs[] = {
74 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
75 { KEX_DH14, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
76 { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
77 #ifdef HAVE_EVP_SHA256
78 { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
79 #endif
80 #ifdef OPENSSL_HAS_ECC
81 { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
82 NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
83 { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
84 SSH_DIGEST_SHA384 },
85 # ifdef OPENSSL_HAS_NISTP521
86 { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
87 SSH_DIGEST_SHA512 },
88 # endif
89 #endif
90 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
91 #ifdef HAVE_EVP_SHA256
92 { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
93 #endif
94 { NULL, -1, -1, -1},
95 };
96
97 char *
kex_alg_list(char sep)98 kex_alg_list(char sep)
99 {
100 char *ret = NULL;
101 size_t nlen, rlen = 0;
102 const struct kexalg *k;
103
104 for (k = kexalgs; k->name != NULL; k++) {
105 if (ret != NULL)
106 ret[rlen++] = sep;
107 nlen = strlen(k->name);
108 ret = xrealloc(ret, 1, rlen + nlen + 2);
109 memcpy(ret + rlen, k->name, nlen + 1);
110 rlen += nlen;
111 }
112 return ret;
113 }
114
115 static const struct kexalg *
kex_alg_by_name(const char * name)116 kex_alg_by_name(const char *name)
117 {
118 const struct kexalg *k;
119
120 for (k = kexalgs; k->name != NULL; k++) {
121 if (strcmp(k->name, name) == 0)
122 return k;
123 }
124 return NULL;
125 }
126
127 /* Validate KEX method name list */
128 int
kex_names_valid(const char * names)129 kex_names_valid(const char *names)
130 {
131 char *s, *cp, *p;
132
133 if (names == NULL || strcmp(names, "") == 0)
134 return 0;
135 s = cp = xstrdup(names);
136 for ((p = strsep(&cp, ",")); p && *p != '\0';
137 (p = strsep(&cp, ","))) {
138 if (kex_alg_by_name(p) == NULL) {
139 error("Unsupported KEX algorithm \"%.100s\"", p);
140 free(s);
141 return 0;
142 }
143 }
144 debug3("kex names ok: [%s]", names);
145 free(s);
146 return 1;
147 }
148
149 /* put algorithm proposal into buffer. */
150 #ifndef NONE_CIPHER_ENABLED
151 static void
152 #else
153 /* Also used in sshconnect2.c. */
154 void
155 #endif
kex_prop2buf(Buffer * b,char * proposal[PROPOSAL_MAX])156 kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
157 {
158 u_int i;
159
160 buffer_clear(b);
161 /*
162 * add a dummy cookie, the cookie will be overwritten by
163 * kex_send_kexinit(), each time a kexinit is set
164 */
165 for (i = 0; i < KEX_COOKIE_LEN; i++)
166 buffer_put_char(b, 0);
167 for (i = 0; i < PROPOSAL_MAX; i++)
168 buffer_put_cstring(b, proposal[i]);
169 buffer_put_char(b, 0); /* first_kex_packet_follows */
170 buffer_put_int(b, 0); /* uint32 reserved */
171 }
172
173 /* parse buffer and return algorithm proposal */
174 static char **
kex_buf2prop(Buffer * raw,int * first_kex_follows)175 kex_buf2prop(Buffer *raw, int *first_kex_follows)
176 {
177 Buffer b;
178 u_int i;
179 char **proposal;
180
181 proposal = xcalloc(PROPOSAL_MAX, sizeof(char *));
182
183 buffer_init(&b);
184 buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
185 /* skip cookie */
186 for (i = 0; i < KEX_COOKIE_LEN; i++)
187 buffer_get_char(&b);
188 /* extract kex init proposal strings */
189 for (i = 0; i < PROPOSAL_MAX; i++) {
190 proposal[i] = buffer_get_cstring(&b,NULL);
191 debug2("kex_parse_kexinit: %s", proposal[i]);
192 }
193 /* first kex follows / reserved */
194 i = buffer_get_char(&b);
195 if (first_kex_follows != NULL)
196 *first_kex_follows = i;
197 debug2("kex_parse_kexinit: first_kex_follows %d ", i);
198 i = buffer_get_int(&b);
199 debug2("kex_parse_kexinit: reserved %u ", i);
200 buffer_free(&b);
201 return proposal;
202 }
203
204 static void
kex_prop_free(char ** proposal)205 kex_prop_free(char **proposal)
206 {
207 u_int i;
208
209 for (i = 0; i < PROPOSAL_MAX; i++)
210 free(proposal[i]);
211 free(proposal);
212 }
213
214 /* ARGSUSED */
215 static void
kex_protocol_error(int type,u_int32_t seq,void * ctxt)216 kex_protocol_error(int type, u_int32_t seq, void *ctxt)
217 {
218 error("Hm, kex protocol error: type %d seq %u", type, seq);
219 }
220
221 static void
kex_reset_dispatch(void)222 kex_reset_dispatch(void)
223 {
224 dispatch_range(SSH2_MSG_TRANSPORT_MIN,
225 SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
226 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
227 }
228
229 void
kex_finish(Kex * kex)230 kex_finish(Kex *kex)
231 {
232 kex_reset_dispatch();
233
234 packet_start(SSH2_MSG_NEWKEYS);
235 packet_send();
236 /* packet_write_wait(); */
237 debug("SSH2_MSG_NEWKEYS sent");
238
239 debug("expecting SSH2_MSG_NEWKEYS");
240 packet_read_expect(SSH2_MSG_NEWKEYS);
241 packet_check_eom();
242 debug("SSH2_MSG_NEWKEYS received");
243
244 kex->done = 1;
245 buffer_clear(&kex->peer);
246 /* buffer_clear(&kex->my); */
247 kex->flags &= ~KEX_INIT_SENT;
248 free(kex->name);
249 kex->name = NULL;
250 }
251
252 void
kex_send_kexinit(Kex * kex)253 kex_send_kexinit(Kex *kex)
254 {
255 u_int32_t rnd = 0;
256 u_char *cookie;
257 u_int i;
258
259 if (kex == NULL) {
260 error("kex_send_kexinit: no kex, cannot rekey");
261 return;
262 }
263 if (kex->flags & KEX_INIT_SENT) {
264 debug("KEX_INIT_SENT");
265 return;
266 }
267 kex->done = 0;
268
269 /* generate a random cookie */
270 if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
271 fatal("kex_send_kexinit: kex proposal too short");
272 cookie = buffer_ptr(&kex->my);
273 for (i = 0; i < KEX_COOKIE_LEN; i++) {
274 if (i % 4 == 0)
275 rnd = arc4random();
276 cookie[i] = rnd;
277 rnd >>= 8;
278 }
279 packet_start(SSH2_MSG_KEXINIT);
280 packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
281 packet_send();
282 debug("SSH2_MSG_KEXINIT sent");
283 kex->flags |= KEX_INIT_SENT;
284 }
285
286 /* ARGSUSED */
287 void
kex_input_kexinit(int type,u_int32_t seq,void * ctxt)288 kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
289 {
290 char *ptr;
291 u_int i, dlen;
292 Kex *kex = (Kex *)ctxt;
293
294 debug("SSH2_MSG_KEXINIT received");
295 if (kex == NULL)
296 fatal("kex_input_kexinit: no kex, cannot rekey");
297
298 ptr = packet_get_raw(&dlen);
299 buffer_append(&kex->peer, ptr, dlen);
300
301 /* discard packet */
302 for (i = 0; i < KEX_COOKIE_LEN; i++)
303 packet_get_char();
304 for (i = 0; i < PROPOSAL_MAX; i++)
305 free(packet_get_string(NULL));
306 /*
307 * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
308 * KEX method has the server move first, but a server might be using
309 * a custom method or one that we otherwise don't support. We should
310 * be prepared to remember first_kex_follows here so we can eat a
311 * packet later.
312 * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
313 * for cases where the server *doesn't* go first. I guess we should
314 * ignore it when it is set for these cases, which is what we do now.
315 */
316 (void) packet_get_char(); /* first_kex_follows */
317 (void) packet_get_int(); /* reserved */
318 packet_check_eom();
319
320 kex_kexinit_finish(kex);
321 }
322
323 Kex *
kex_setup(char * proposal[PROPOSAL_MAX])324 kex_setup(char *proposal[PROPOSAL_MAX])
325 {
326 Kex *kex;
327
328 kex = xcalloc(1, sizeof(*kex));
329 buffer_init(&kex->peer);
330 buffer_init(&kex->my);
331 kex_prop2buf(&kex->my, proposal);
332 kex->done = 0;
333
334 kex_send_kexinit(kex); /* we start */
335 kex_reset_dispatch();
336
337 return kex;
338 }
339
340 static void
kex_kexinit_finish(Kex * kex)341 kex_kexinit_finish(Kex *kex)
342 {
343 if (!(kex->flags & KEX_INIT_SENT))
344 kex_send_kexinit(kex);
345
346 kex_choose_conf(kex);
347
348 if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
349 kex->kex[kex->kex_type] != NULL) {
350 (kex->kex[kex->kex_type])(kex);
351 } else {
352 fatal("Unsupported key exchange %d", kex->kex_type);
353 }
354 }
355
356 static void
choose_enc(Enc * enc,char * client,char * server)357 choose_enc(Enc *enc, char *client, char *server)
358 {
359 char *name = match_list(client, server, NULL);
360 if (name == NULL)
361 fatal("no matching cipher found: client %s server %s",
362 client, server);
363 if ((enc->cipher = cipher_by_name(name)) == NULL)
364 fatal("matching cipher is not supported: %s", name);
365 enc->name = name;
366 enc->enabled = 0;
367 enc->iv = NULL;
368 enc->iv_len = cipher_ivlen(enc->cipher);
369 enc->key = NULL;
370 enc->key_len = cipher_keylen(enc->cipher);
371 enc->block_size = cipher_blocksize(enc->cipher);
372 }
373
374 static void
choose_mac(Mac * mac,char * client,char * server)375 choose_mac(Mac *mac, char *client, char *server)
376 {
377 char *name = match_list(client, server, NULL);
378 if (name == NULL)
379 fatal("no matching mac found: client %s server %s",
380 client, server);
381 if (mac_setup(mac, name) < 0)
382 fatal("unsupported mac %s", name);
383 /* truncate the key */
384 if (datafellows & SSH_BUG_HMAC)
385 mac->key_len = 16;
386 mac->name = name;
387 mac->key = NULL;
388 mac->enabled = 0;
389 }
390
391 static void
choose_comp(Comp * comp,char * client,char * server)392 choose_comp(Comp *comp, char *client, char *server)
393 {
394 char *name = match_list(client, server, NULL);
395 if (name == NULL)
396 fatal("no matching comp found: client %s server %s", client, server);
397 if (strcmp(name, "zlib@openssh.com") == 0) {
398 comp->type = COMP_DELAYED;
399 } else if (strcmp(name, "zlib") == 0) {
400 comp->type = COMP_ZLIB;
401 } else if (strcmp(name, "none") == 0) {
402 comp->type = COMP_NONE;
403 } else {
404 fatal("unsupported comp %s", name);
405 }
406 comp->name = name;
407 }
408
409 static void
choose_kex(Kex * k,char * client,char * server)410 choose_kex(Kex *k, char *client, char *server)
411 {
412 const struct kexalg *kexalg;
413
414 k->name = match_list(client, server, NULL);
415 if (k->name == NULL)
416 fatal("Unable to negotiate a key exchange method");
417 if ((kexalg = kex_alg_by_name(k->name)) == NULL)
418 fatal("unsupported kex alg %s", k->name);
419 k->kex_type = kexalg->type;
420 k->hash_alg = kexalg->hash_alg;
421 k->ec_nid = kexalg->ec_nid;
422 }
423
424 static void
choose_hostkeyalg(Kex * k,char * client,char * server)425 choose_hostkeyalg(Kex *k, char *client, char *server)
426 {
427 char *hostkeyalg = match_list(client, server, NULL);
428 if (hostkeyalg == NULL)
429 fatal("no hostkey alg");
430 k->hostkey_type = key_type_from_name(hostkeyalg);
431 if (k->hostkey_type == KEY_UNSPEC)
432 fatal("bad hostkey alg '%s'", hostkeyalg);
433 free(hostkeyalg);
434 }
435
436 static int
proposals_match(char * my[PROPOSAL_MAX],char * peer[PROPOSAL_MAX])437 proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
438 {
439 static int check[] = {
440 PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
441 };
442 int *idx;
443 char *p;
444
445 for (idx = &check[0]; *idx != -1; idx++) {
446 if ((p = strchr(my[*idx], ',')) != NULL)
447 *p = '\0';
448 if ((p = strchr(peer[*idx], ',')) != NULL)
449 *p = '\0';
450 if (strcmp(my[*idx], peer[*idx]) != 0) {
451 debug2("proposal mismatch: my %s peer %s",
452 my[*idx], peer[*idx]);
453 return (0);
454 }
455 }
456 debug2("proposals match");
457 return (1);
458 }
459
460 static void
kex_choose_conf(Kex * kex)461 kex_choose_conf(Kex *kex)
462 {
463 Newkeys *newkeys;
464 char **my, **peer;
465 char **cprop, **sprop;
466 int nenc, nmac, ncomp;
467 u_int mode, ctos, need, dh_need, authlen;
468 int first_kex_follows, type;
469 #ifdef NONE_CIPHER_ENABLED
470 int auth_flag;
471 #endif
472
473 my = kex_buf2prop(&kex->my, NULL);
474 peer = kex_buf2prop(&kex->peer, &first_kex_follows);
475
476 if (kex->server) {
477 cprop=peer;
478 sprop=my;
479 } else {
480 cprop=my;
481 sprop=peer;
482 }
483
484 /* Check whether server offers roaming */
485 if (!kex->server) {
486 char *roaming;
487 roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL);
488 if (roaming) {
489 kex->roaming = 1;
490 free(roaming);
491 }
492 }
493
494 /* Algorithm Negotiation */
495 #ifdef NONE_CIPHER_ENABLED
496 auth_flag = packet_get_authentication_state();
497 debug ("AUTH STATE is %d", auth_flag);
498 #endif
499 for (mode = 0; mode < MODE_MAX; mode++) {
500 newkeys = xcalloc(1, sizeof(*newkeys));
501 kex->newkeys[mode] = newkeys;
502 ctos = (!kex->server && mode == MODE_OUT) ||
503 (kex->server && mode == MODE_IN);
504 nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
505 nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
506 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
507 choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]);
508 /* ignore mac for authenticated encryption */
509 authlen = cipher_authlen(newkeys->enc.cipher);
510 if (authlen == 0)
511 choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]);
512 choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
513 #ifdef NONE_CIPHER_ENABLED
514 debug("REQUESTED ENC.NAME is '%s'", newkeys->enc.name);
515 if (strcmp(newkeys->enc.name, "none") == 0) {
516 debug("Requesting NONE. Authflag is %d", auth_flag);
517 if (auth_flag == 1)
518 debug("None requested post authentication.");
519 else
520 fatal("Pre-authentication none cipher requests "
521 "are not allowed.");
522 }
523 #endif
524 debug("kex: %s %s %s %s",
525 ctos ? "client->server" : "server->client",
526 newkeys->enc.name,
527 authlen == 0 ? newkeys->mac.name : "<implicit>",
528 newkeys->comp.name);
529 }
530 choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
531 choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
532 sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
533 need = dh_need = 0;
534 for (mode = 0; mode < MODE_MAX; mode++) {
535 newkeys = kex->newkeys[mode];
536 need = MAX(need, newkeys->enc.key_len);
537 need = MAX(need, newkeys->enc.block_size);
538 need = MAX(need, newkeys->enc.iv_len);
539 need = MAX(need, newkeys->mac.key_len);
540 dh_need = MAX(dh_need, cipher_seclen(newkeys->enc.cipher));
541 dh_need = MAX(dh_need, newkeys->enc.block_size);
542 dh_need = MAX(dh_need, newkeys->enc.iv_len);
543 dh_need = MAX(dh_need, newkeys->mac.key_len);
544 }
545 /* XXX need runden? */
546 kex->we_need = need;
547 kex->dh_need = dh_need;
548
549 /* ignore the next message if the proposals do not match */
550 if (first_kex_follows && !proposals_match(my, peer) &&
551 !(datafellows & SSH_BUG_FIRSTKEX)) {
552 type = packet_read();
553 debug2("skipping next packet (type %u)", type);
554 }
555
556 kex_prop_free(my);
557 kex_prop_free(peer);
558 }
559
560 static u_char *
derive_key(Kex * kex,int id,u_int need,u_char * hash,u_int hashlen,const u_char * shared_secret,u_int slen)561 derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen,
562 const u_char *shared_secret, u_int slen)
563 {
564 Buffer b;
565 struct ssh_digest_ctx *hashctx;
566 char c = id;
567 u_int have;
568 size_t mdsz;
569 u_char *digest;
570
571 if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
572 fatal("bad kex md size %zu", mdsz);
573 digest = xmalloc(roundup(need, mdsz));
574
575 buffer_init(&b);
576 buffer_append(&b, shared_secret, slen);
577
578 /* K1 = HASH(K || H || "A" || session_id) */
579 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL)
580 fatal("%s: ssh_digest_start failed", __func__);
581 if (ssh_digest_update_buffer(hashctx, &b) != 0 ||
582 ssh_digest_update(hashctx, hash, hashlen) != 0 ||
583 ssh_digest_update(hashctx, &c, 1) != 0 ||
584 ssh_digest_update(hashctx, kex->session_id,
585 kex->session_id_len) != 0)
586 fatal("%s: ssh_digest_update failed", __func__);
587 if (ssh_digest_final(hashctx, digest, mdsz) != 0)
588 fatal("%s: ssh_digest_final failed", __func__);
589 ssh_digest_free(hashctx);
590
591 /*
592 * expand key:
593 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
594 * Key = K1 || K2 || ... || Kn
595 */
596 for (have = mdsz; need > have; have += mdsz) {
597 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL)
598 fatal("%s: ssh_digest_start failed", __func__);
599 if (ssh_digest_update_buffer(hashctx, &b) != 0 ||
600 ssh_digest_update(hashctx, hash, hashlen) != 0 ||
601 ssh_digest_update(hashctx, digest, have) != 0)
602 fatal("%s: ssh_digest_update failed", __func__);
603 if (ssh_digest_final(hashctx, digest + have, mdsz) != 0)
604 fatal("%s: ssh_digest_final failed", __func__);
605 ssh_digest_free(hashctx);
606 }
607 buffer_free(&b);
608 #ifdef DEBUG_KEX
609 fprintf(stderr, "key '%c'== ", c);
610 dump_digest("key", digest, need);
611 #endif
612 return digest;
613 }
614
615 Newkeys *current_keys[MODE_MAX];
616
617 #define NKEYS 6
618 void
kex_derive_keys(Kex * kex,u_char * hash,u_int hashlen,const u_char * shared_secret,u_int slen)619 kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen,
620 const u_char *shared_secret, u_int slen)
621 {
622 u_char *keys[NKEYS];
623 u_int i, mode, ctos;
624
625 for (i = 0; i < NKEYS; i++) {
626 keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen,
627 shared_secret, slen);
628 }
629
630 debug2("kex_derive_keys");
631 for (mode = 0; mode < MODE_MAX; mode++) {
632 current_keys[mode] = kex->newkeys[mode];
633 kex->newkeys[mode] = NULL;
634 ctos = (!kex->server && mode == MODE_OUT) ||
635 (kex->server && mode == MODE_IN);
636 current_keys[mode]->enc.iv = keys[ctos ? 0 : 1];
637 current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
638 current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
639 }
640 }
641
642 void
kex_derive_keys_bn(Kex * kex,u_char * hash,u_int hashlen,const BIGNUM * secret)643 kex_derive_keys_bn(Kex *kex, u_char *hash, u_int hashlen, const BIGNUM *secret)
644 {
645 Buffer shared_secret;
646
647 buffer_init(&shared_secret);
648 buffer_put_bignum2(&shared_secret, secret);
649 kex_derive_keys(kex, hash, hashlen,
650 buffer_ptr(&shared_secret), buffer_len(&shared_secret));
651 buffer_free(&shared_secret);
652 }
653
654 Newkeys *
kex_get_newkeys(int mode)655 kex_get_newkeys(int mode)
656 {
657 Newkeys *ret;
658
659 ret = current_keys[mode];
660 current_keys[mode] = NULL;
661 return ret;
662 }
663
664 void
derive_ssh1_session_id(BIGNUM * host_modulus,BIGNUM * server_modulus,u_int8_t cookie[8],u_int8_t id[16])665 derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
666 u_int8_t cookie[8], u_int8_t id[16])
667 {
668 u_int8_t nbuf[2048], obuf[SSH_DIGEST_MAX_LENGTH];
669 int len;
670 struct ssh_digest_ctx *hashctx;
671
672 if ((hashctx = ssh_digest_start(SSH_DIGEST_MD5)) == NULL)
673 fatal("%s: ssh_digest_start", __func__);
674
675 len = BN_num_bytes(host_modulus);
676 if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
677 fatal("%s: bad host modulus (len %d)", __func__, len);
678 BN_bn2bin(host_modulus, nbuf);
679 if (ssh_digest_update(hashctx, nbuf, len) != 0)
680 fatal("%s: ssh_digest_update failed", __func__);
681
682 len = BN_num_bytes(server_modulus);
683 if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
684 fatal("%s: bad server modulus (len %d)", __func__, len);
685 BN_bn2bin(server_modulus, nbuf);
686 if (ssh_digest_update(hashctx, nbuf, len) != 0 ||
687 ssh_digest_update(hashctx, cookie, 8) != 0)
688 fatal("%s: ssh_digest_update failed", __func__);
689 if (ssh_digest_final(hashctx, obuf, sizeof(obuf)) != 0)
690 fatal("%s: ssh_digest_final failed", __func__);
691 memcpy(id, obuf, ssh_digest_bytes(SSH_DIGEST_MD5));
692
693 explicit_bzero(nbuf, sizeof(nbuf));
694 explicit_bzero(obuf, sizeof(obuf));
695 }
696
697 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
698 void
dump_digest(char * msg,u_char * digest,int len)699 dump_digest(char *msg, u_char *digest, int len)
700 {
701 int i;
702
703 fprintf(stderr, "%s\n", msg);
704 for (i = 0; i < len; i++) {
705 fprintf(stderr, "%02x", digest[i]);
706 if (i%32 == 31)
707 fprintf(stderr, "\n");
708 else if (i%8 == 7)
709 fprintf(stderr, " ");
710 }
711 fprintf(stderr, "\n");
712 }
713 #endif
714