1 /* $OpenBSD: kex.c,v 1.98 2014/02/02 03:44:31 djm Exp $ */
2 /*
3 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
4 *
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.
13 *
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"
27
28 #include <sys/param.h>
29
30 #include <signal.h>
31 #include <stdarg.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35
36 #include <openssl/crypto.h>
37
38 #include "xmalloc.h"
39 #include "ssh2.h"
40 #include "buffer.h"
41 #include "packet.h"
42 #include "compat.h"
43 #include "cipher.h"
44 #include "key.h"
45 #include "kex.h"
46 #include "log.h"
47 #include "mac.h"
48 #include "match.h"
49 #include "dispatch.h"
50 #include "monitor.h"
51 #include "roaming.h"
52 #include "digest.h"
53
54 #if OPENSSL_VERSION_NUMBER >= 0x00907000L
55 # if defined(HAVE_EVP_SHA256)
56 # define evp_ssh_sha256 EVP_sha256
57 # else
58 extern const EVP_MD *evp_ssh_sha256(void);
59 # endif
60 #endif
61
62 /* prototype */
63 static void kex_kexinit_finish(Kex *);
64 static void kex_choose_conf(Kex *);
65
66 struct kexalg {
67 char *name;
68 int type;
69 int ec_nid;
70 int hash_alg;
71 };
72 static const struct kexalg kexalgs[] = {
73 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
74 { KEX_DH14, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
75 { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
76 #ifdef HAVE_EVP_SHA256
77 { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
78 #endif
79 #ifdef OPENSSL_HAS_ECC
80 { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
81 NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
82 { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
83 SSH_DIGEST_SHA384 },
84 # ifdef OPENSSL_HAS_NISTP521
85 { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
86 SSH_DIGEST_SHA512 },
87 # endif
88 #endif
89 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
90 #ifdef HAVE_EVP_SHA256
91 { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
92 #endif
93 { NULL, -1, -1, -1},
94 };
95
96 char *
kex_alg_list(char sep)97 kex_alg_list(char sep)
98 {
99 char *ret = NULL;
100 size_t nlen, rlen = 0;
101 const struct kexalg *k;
102
103 for (k = kexalgs; k->name != NULL; k++) {
104 if (ret != NULL)
105 ret[rlen++] = sep;
106 nlen = strlen(k->name);
107 ret = xrealloc(ret, 1, rlen + nlen + 2);
108 memcpy(ret + rlen, k->name, nlen + 1);
109 rlen += nlen;
110 }
111 return ret;
112 }
113
114 static const struct kexalg *
kex_alg_by_name(const char * name)115 kex_alg_by_name(const char *name)
116 {
117 const struct kexalg *k;
118
119 for (k = kexalgs; k->name != NULL; k++) {
120 if (strcmp(k->name, name) == 0)
121 return k;
122 }
123 return NULL;
124 }
125
126 /* Validate KEX method name list */
127 int
kex_names_valid(const char * names)128 kex_names_valid(const char *names)
129 {
130 char *s, *cp, *p;
131
132 if (names == NULL || strcmp(names, "") == 0)
133 return 0;
134 s = cp = xstrdup(names);
135 for ((p = strsep(&cp, ",")); p && *p != '\0';
136 (p = strsep(&cp, ","))) {
137 if (kex_alg_by_name(p) == NULL) {
138 error("Unsupported KEX algorithm \"%.100s\"", p);
139 free(s);
140 return 0;
141 }
142 }
143 debug3("kex names ok: [%s]", names);
144 free(s);
145 return 1;
146 }
147
148 /* put algorithm proposal into buffer */
149 static void
kex_prop2buf(Buffer * b,char * proposal[PROPOSAL_MAX])150 kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
151 {
152 u_int i;
153
154 buffer_clear(b);
155 /*
156 * add a dummy cookie, the cookie will be overwritten by
157 * kex_send_kexinit(), each time a kexinit is set
158 */
159 for (i = 0; i < KEX_COOKIE_LEN; i++)
160 buffer_put_char(b, 0);
161 for (i = 0; i < PROPOSAL_MAX; i++)
162 buffer_put_cstring(b, proposal[i]);
163 buffer_put_char(b, 0); /* first_kex_packet_follows */
164 buffer_put_int(b, 0); /* uint32 reserved */
165 }
166
167 /* parse buffer and return algorithm proposal */
168 static char **
kex_buf2prop(Buffer * raw,int * first_kex_follows)169 kex_buf2prop(Buffer *raw, int *first_kex_follows)
170 {
171 Buffer b;
172 u_int i;
173 char **proposal;
174
175 proposal = xcalloc(PROPOSAL_MAX, sizeof(char *));
176
177 buffer_init(&b);
178 buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
179 /* skip cookie */
180 for (i = 0; i < KEX_COOKIE_LEN; i++)
181 buffer_get_char(&b);
182 /* extract kex init proposal strings */
183 for (i = 0; i < PROPOSAL_MAX; i++) {
184 proposal[i] = buffer_get_cstring(&b,NULL);
185 debug2("kex_parse_kexinit: %s", proposal[i]);
186 }
187 /* first kex follows / reserved */
188 i = buffer_get_char(&b);
189 if (first_kex_follows != NULL)
190 *first_kex_follows = i;
191 debug2("kex_parse_kexinit: first_kex_follows %d ", i);
192 i = buffer_get_int(&b);
193 debug2("kex_parse_kexinit: reserved %u ", i);
194 buffer_free(&b);
195 return proposal;
196 }
197
198 static void
kex_prop_free(char ** proposal)199 kex_prop_free(char **proposal)
200 {
201 u_int i;
202
203 for (i = 0; i < PROPOSAL_MAX; i++)
204 free(proposal[i]);
205 free(proposal);
206 }
207
208 /* ARGSUSED */
209 static void
kex_protocol_error(int type,u_int32_t seq,void * ctxt)210 kex_protocol_error(int type, u_int32_t seq, void *ctxt)
211 {
212 error("Hm, kex protocol error: type %d seq %u", type, seq);
213 }
214
215 static void
kex_reset_dispatch(void)216 kex_reset_dispatch(void)
217 {
218 dispatch_range(SSH2_MSG_TRANSPORT_MIN,
219 SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
220 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
221 }
222
223 void
kex_finish(Kex * kex)224 kex_finish(Kex *kex)
225 {
226 kex_reset_dispatch();
227
228 packet_start(SSH2_MSG_NEWKEYS);
229 packet_send();
230 /* packet_write_wait(); */
231 debug("SSH2_MSG_NEWKEYS sent");
232
233 debug("expecting SSH2_MSG_NEWKEYS");
234 packet_read_expect(SSH2_MSG_NEWKEYS);
235 packet_check_eom();
236 debug("SSH2_MSG_NEWKEYS received");
237
238 kex->done = 1;
239 buffer_clear(&kex->peer);
240 /* buffer_clear(&kex->my); */
241 kex->flags &= ~KEX_INIT_SENT;
242 free(kex->name);
243 kex->name = NULL;
244 }
245
246 void
kex_send_kexinit(Kex * kex)247 kex_send_kexinit(Kex *kex)
248 {
249 u_int32_t rnd = 0;
250 u_char *cookie;
251 u_int i;
252
253 if (kex == NULL) {
254 error("kex_send_kexinit: no kex, cannot rekey");
255 return;
256 }
257 if (kex->flags & KEX_INIT_SENT) {
258 debug("KEX_INIT_SENT");
259 return;
260 }
261 kex->done = 0;
262
263 /* generate a random cookie */
264 if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
265 fatal("kex_send_kexinit: kex proposal too short");
266 cookie = buffer_ptr(&kex->my);
267 for (i = 0; i < KEX_COOKIE_LEN; i++) {
268 if (i % 4 == 0)
269 rnd = arc4random();
270 cookie[i] = rnd;
271 rnd >>= 8;
272 }
273 packet_start(SSH2_MSG_KEXINIT);
274 packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
275 packet_send();
276 debug("SSH2_MSG_KEXINIT sent");
277 kex->flags |= KEX_INIT_SENT;
278 }
279
280 /* ARGSUSED */
281 void
kex_input_kexinit(int type,u_int32_t seq,void * ctxt)282 kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
283 {
284 char *ptr;
285 u_int i, dlen;
286 Kex *kex = (Kex *)ctxt;
287
288 debug("SSH2_MSG_KEXINIT received");
289 if (kex == NULL)
290 fatal("kex_input_kexinit: no kex, cannot rekey");
291
292 ptr = packet_get_raw(&dlen);
293 buffer_append(&kex->peer, ptr, dlen);
294
295 /* discard packet */
296 for (i = 0; i < KEX_COOKIE_LEN; i++)
297 packet_get_char();
298 for (i = 0; i < PROPOSAL_MAX; i++)
299 free(packet_get_string(NULL));
300 /*
301 * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
302 * KEX method has the server move first, but a server might be using
303 * a custom method or one that we otherwise don't support. We should
304 * be prepared to remember first_kex_follows here so we can eat a
305 * packet later.
306 * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
307 * for cases where the server *doesn't* go first. I guess we should
308 * ignore it when it is set for these cases, which is what we do now.
309 */
310 (void) packet_get_char(); /* first_kex_follows */
311 (void) packet_get_int(); /* reserved */
312 packet_check_eom();
313
314 kex_kexinit_finish(kex);
315 }
316
317 Kex *
kex_setup(char * proposal[PROPOSAL_MAX])318 kex_setup(char *proposal[PROPOSAL_MAX])
319 {
320 Kex *kex;
321
322 kex = xcalloc(1, sizeof(*kex));
323 buffer_init(&kex->peer);
324 buffer_init(&kex->my);
325 kex_prop2buf(&kex->my, proposal);
326 kex->done = 0;
327
328 kex_send_kexinit(kex); /* we start */
329 kex_reset_dispatch();
330
331 return kex;
332 }
333
334 static void
kex_kexinit_finish(Kex * kex)335 kex_kexinit_finish(Kex *kex)
336 {
337 if (!(kex->flags & KEX_INIT_SENT))
338 kex_send_kexinit(kex);
339
340 kex_choose_conf(kex);
341
342 if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
343 kex->kex[kex->kex_type] != NULL) {
344 (kex->kex[kex->kex_type])(kex);
345 } else {
346 fatal("Unsupported key exchange %d", kex->kex_type);
347 }
348 }
349
350 static void
choose_enc(Enc * enc,char * client,char * server)351 choose_enc(Enc *enc, char *client, char *server)
352 {
353 char *name = match_list(client, server, NULL);
354 if (name == NULL)
355 fatal("no matching cipher found: client %s server %s",
356 client, server);
357 if ((enc->cipher = cipher_by_name(name)) == NULL)
358 fatal("matching cipher is not supported: %s", name);
359 enc->name = name;
360 enc->enabled = 0;
361 enc->iv = NULL;
362 enc->iv_len = cipher_ivlen(enc->cipher);
363 enc->key = NULL;
364 enc->key_len = cipher_keylen(enc->cipher);
365 enc->block_size = cipher_blocksize(enc->cipher);
366 }
367
368 static void
choose_mac(Mac * mac,char * client,char * server)369 choose_mac(Mac *mac, char *client, char *server)
370 {
371 char *name = match_list(client, server, NULL);
372 if (name == NULL)
373 fatal("no matching mac found: client %s server %s",
374 client, server);
375 if (mac_setup(mac, name) < 0)
376 fatal("unsupported mac %s", name);
377 /* truncate the key */
378 if (datafellows & SSH_BUG_HMAC)
379 mac->key_len = 16;
380 mac->name = name;
381 mac->key = NULL;
382 mac->enabled = 0;
383 }
384
385 static void
choose_comp(Comp * comp,char * client,char * server)386 choose_comp(Comp *comp, char *client, char *server)
387 {
388 char *name = match_list(client, server, NULL);
389 if (name == NULL)
390 fatal("no matching comp found: client %s server %s", client, server);
391 if (strcmp(name, "zlib@openssh.com") == 0) {
392 comp->type = COMP_DELAYED;
393 } else if (strcmp(name, "zlib") == 0) {
394 comp->type = COMP_ZLIB;
395 } else if (strcmp(name, "none") == 0) {
396 comp->type = COMP_NONE;
397 } else {
398 fatal("unsupported comp %s", name);
399 }
400 comp->name = name;
401 }
402
403 static void
choose_kex(Kex * k,char * client,char * server)404 choose_kex(Kex *k, char *client, char *server)
405 {
406 const struct kexalg *kexalg;
407
408 k->name = match_list(client, server, NULL);
409 if (k->name == NULL)
410 fatal("Unable to negotiate a key exchange method");
411 if ((kexalg = kex_alg_by_name(k->name)) == NULL)
412 fatal("unsupported kex alg %s", k->name);
413 k->kex_type = kexalg->type;
414 k->hash_alg = kexalg->hash_alg;
415 k->ec_nid = kexalg->ec_nid;
416 }
417
418 static void
choose_hostkeyalg(Kex * k,char * client,char * server)419 choose_hostkeyalg(Kex *k, char *client, char *server)
420 {
421 char *hostkeyalg = match_list(client, server, NULL);
422 if (hostkeyalg == NULL)
423 fatal("no hostkey alg");
424 k->hostkey_type = key_type_from_name(hostkeyalg);
425 if (k->hostkey_type == KEY_UNSPEC)
426 fatal("bad hostkey alg '%s'", hostkeyalg);
427 free(hostkeyalg);
428 }
429
430 static int
proposals_match(char * my[PROPOSAL_MAX],char * peer[PROPOSAL_MAX])431 proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
432 {
433 static int check[] = {
434 PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
435 };
436 int *idx;
437 char *p;
438
439 for (idx = &check[0]; *idx != -1; idx++) {
440 if ((p = strchr(my[*idx], ',')) != NULL)
441 *p = '\0';
442 if ((p = strchr(peer[*idx], ',')) != NULL)
443 *p = '\0';
444 if (strcmp(my[*idx], peer[*idx]) != 0) {
445 debug2("proposal mismatch: my %s peer %s",
446 my[*idx], peer[*idx]);
447 return (0);
448 }
449 }
450 debug2("proposals match");
451 return (1);
452 }
453
454 static void
kex_choose_conf(Kex * kex)455 kex_choose_conf(Kex *kex)
456 {
457 Newkeys *newkeys;
458 char **my, **peer;
459 char **cprop, **sprop;
460 int nenc, nmac, ncomp;
461 u_int mode, ctos, need, dh_need, authlen;
462 int first_kex_follows, type;
463
464 my = kex_buf2prop(&kex->my, NULL);
465 peer = kex_buf2prop(&kex->peer, &first_kex_follows);
466
467 if (kex->server) {
468 cprop=peer;
469 sprop=my;
470 } else {
471 cprop=my;
472 sprop=peer;
473 }
474
475 /* Check whether server offers roaming */
476 if (!kex->server) {
477 char *roaming;
478 roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL);
479 if (roaming) {
480 kex->roaming = 1;
481 free(roaming);
482 }
483 }
484
485 /* Algorithm Negotiation */
486 for (mode = 0; mode < MODE_MAX; mode++) {
487 newkeys = xcalloc(1, sizeof(*newkeys));
488 kex->newkeys[mode] = newkeys;
489 ctos = (!kex->server && mode == MODE_OUT) ||
490 (kex->server && mode == MODE_IN);
491 nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
492 nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
493 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
494 choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]);
495 /* ignore mac for authenticated encryption */
496 authlen = cipher_authlen(newkeys->enc.cipher);
497 if (authlen == 0)
498 choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]);
499 choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
500 debug("kex: %s %s %s %s",
501 ctos ? "client->server" : "server->client",
502 newkeys->enc.name,
503 authlen == 0 ? newkeys->mac.name : "<implicit>",
504 newkeys->comp.name);
505 }
506 choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
507 choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
508 sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
509 need = dh_need = 0;
510 for (mode = 0; mode < MODE_MAX; mode++) {
511 newkeys = kex->newkeys[mode];
512 need = MAX(need, newkeys->enc.key_len);
513 need = MAX(need, newkeys->enc.block_size);
514 need = MAX(need, newkeys->enc.iv_len);
515 need = MAX(need, newkeys->mac.key_len);
516 dh_need = MAX(dh_need, cipher_seclen(newkeys->enc.cipher));
517 dh_need = MAX(dh_need, newkeys->enc.block_size);
518 dh_need = MAX(dh_need, newkeys->enc.iv_len);
519 dh_need = MAX(dh_need, newkeys->mac.key_len);
520 }
521 /* XXX need runden? */
522 kex->we_need = need;
523 kex->dh_need = dh_need;
524
525 /* ignore the next message if the proposals do not match */
526 if (first_kex_follows && !proposals_match(my, peer) &&
527 !(datafellows & SSH_BUG_FIRSTKEX)) {
528 type = packet_read();
529 debug2("skipping next packet (type %u)", type);
530 }
531
532 kex_prop_free(my);
533 kex_prop_free(peer);
534 }
535
536 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)537 derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen,
538 const u_char *shared_secret, u_int slen)
539 {
540 Buffer b;
541 struct ssh_digest_ctx *hashctx;
542 char c = id;
543 u_int have;
544 size_t mdsz;
545 u_char *digest;
546
547 if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
548 fatal("bad kex md size %zu", mdsz);
549 digest = xmalloc(roundup(need, mdsz));
550
551 buffer_init(&b);
552 buffer_append(&b, shared_secret, slen);
553
554 /* K1 = HASH(K || H || "A" || session_id) */
555 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL)
556 fatal("%s: ssh_digest_start failed", __func__);
557 if (ssh_digest_update_buffer(hashctx, &b) != 0 ||
558 ssh_digest_update(hashctx, hash, hashlen) != 0 ||
559 ssh_digest_update(hashctx, &c, 1) != 0 ||
560 ssh_digest_update(hashctx, kex->session_id,
561 kex->session_id_len) != 0)
562 fatal("%s: ssh_digest_update failed", __func__);
563 if (ssh_digest_final(hashctx, digest, mdsz) != 0)
564 fatal("%s: ssh_digest_final failed", __func__);
565 ssh_digest_free(hashctx);
566
567 /*
568 * expand key:
569 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
570 * Key = K1 || K2 || ... || Kn
571 */
572 for (have = mdsz; need > have; have += mdsz) {
573 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL)
574 fatal("%s: ssh_digest_start failed", __func__);
575 if (ssh_digest_update_buffer(hashctx, &b) != 0 ||
576 ssh_digest_update(hashctx, hash, hashlen) != 0 ||
577 ssh_digest_update(hashctx, digest, have) != 0)
578 fatal("%s: ssh_digest_update failed", __func__);
579 if (ssh_digest_final(hashctx, digest + have, mdsz) != 0)
580 fatal("%s: ssh_digest_final failed", __func__);
581 ssh_digest_free(hashctx);
582 }
583 buffer_free(&b);
584 #ifdef DEBUG_KEX
585 fprintf(stderr, "key '%c'== ", c);
586 dump_digest("key", digest, need);
587 #endif
588 return digest;
589 }
590
591 Newkeys *current_keys[MODE_MAX];
592
593 #define NKEYS 6
594 void
kex_derive_keys(Kex * kex,u_char * hash,u_int hashlen,const u_char * shared_secret,u_int slen)595 kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen,
596 const u_char *shared_secret, u_int slen)
597 {
598 u_char *keys[NKEYS];
599 u_int i, mode, ctos;
600
601 for (i = 0; i < NKEYS; i++) {
602 keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen,
603 shared_secret, slen);
604 }
605
606 debug2("kex_derive_keys");
607 for (mode = 0; mode < MODE_MAX; mode++) {
608 current_keys[mode] = kex->newkeys[mode];
609 kex->newkeys[mode] = NULL;
610 ctos = (!kex->server && mode == MODE_OUT) ||
611 (kex->server && mode == MODE_IN);
612 current_keys[mode]->enc.iv = keys[ctos ? 0 : 1];
613 current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
614 current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
615 }
616 }
617
618 void
kex_derive_keys_bn(Kex * kex,u_char * hash,u_int hashlen,const BIGNUM * secret)619 kex_derive_keys_bn(Kex *kex, u_char *hash, u_int hashlen, const BIGNUM *secret)
620 {
621 Buffer shared_secret;
622
623 buffer_init(&shared_secret);
624 buffer_put_bignum2(&shared_secret, secret);
625 kex_derive_keys(kex, hash, hashlen,
626 buffer_ptr(&shared_secret), buffer_len(&shared_secret));
627 buffer_free(&shared_secret);
628 }
629
630 Newkeys *
kex_get_newkeys(int mode)631 kex_get_newkeys(int mode)
632 {
633 Newkeys *ret;
634
635 ret = current_keys[mode];
636 current_keys[mode] = NULL;
637 return ret;
638 }
639
640 void
derive_ssh1_session_id(BIGNUM * host_modulus,BIGNUM * server_modulus,u_int8_t cookie[8],u_int8_t id[16])641 derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
642 u_int8_t cookie[8], u_int8_t id[16])
643 {
644 u_int8_t nbuf[2048], obuf[SSH_DIGEST_MAX_LENGTH];
645 int len;
646 struct ssh_digest_ctx *hashctx;
647
648 if ((hashctx = ssh_digest_start(SSH_DIGEST_MD5)) == NULL)
649 fatal("%s: ssh_digest_start", __func__);
650
651 len = BN_num_bytes(host_modulus);
652 if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
653 fatal("%s: bad host modulus (len %d)", __func__, len);
654 BN_bn2bin(host_modulus, nbuf);
655 if (ssh_digest_update(hashctx, nbuf, len) != 0)
656 fatal("%s: ssh_digest_update failed", __func__);
657
658 len = BN_num_bytes(server_modulus);
659 if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
660 fatal("%s: bad server modulus (len %d)", __func__, len);
661 BN_bn2bin(server_modulus, nbuf);
662 if (ssh_digest_update(hashctx, nbuf, len) != 0 ||
663 ssh_digest_update(hashctx, cookie, 8) != 0)
664 fatal("%s: ssh_digest_update failed", __func__);
665 if (ssh_digest_final(hashctx, obuf, sizeof(obuf)) != 0)
666 fatal("%s: ssh_digest_final failed", __func__);
667 memcpy(id, obuf, ssh_digest_bytes(SSH_DIGEST_MD5));
668
669 explicit_bzero(nbuf, sizeof(nbuf));
670 explicit_bzero(obuf, sizeof(obuf));
671 }
672
673 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
674 void
dump_digest(char * msg,u_char * digest,int len)675 dump_digest(char *msg, u_char *digest, int len)
676 {
677 int i;
678
679 fprintf(stderr, "%s\n", msg);
680 for (i = 0; i < len; i++) {
681 fprintf(stderr, "%02x", digest[i]);
682 if (i%32 == 31)
683 fprintf(stderr, "\n");
684 else if (i%8 == 7)
685 fprintf(stderr, " ");
686 }
687 fprintf(stderr, "\n");
688 }
689 #endif
690