1 /* $OpenBSD: kex.c,v 1.99 2014/04/29 18:01:49 markus 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 #ifdef WITH_OPENSSL 37 #include <openssl/crypto.h> 38 #endif 39 40 #include "xmalloc.h" 41 #include "ssh2.h" 42 #include "buffer.h" 43 #include "packet.h" 44 #include "compat.h" 45 #include "cipher.h" 46 #include "key.h" 47 #include "kex.h" 48 #include "log.h" 49 #include "mac.h" 50 #include "match.h" 51 #include "dispatch.h" 52 #include "monitor.h" 53 #include "roaming.h" 54 #include "canohost.h" 55 #include "digest.h" 56 57 #if OPENSSL_VERSION_NUMBER >= 0x00907000L 58 # if defined(HAVE_EVP_SHA256) 59 # define evp_ssh_sha256 EVP_sha256 60 # else 61 extern const EVP_MD *evp_ssh_sha256(void); 62 # endif 63 #endif 64 65 /* prototype */ 66 static void kex_kexinit_finish(Kex *); 67 static void kex_choose_conf(Kex *); 68 69 struct kexalg { 70 char *name; 71 int type; 72 int ec_nid; 73 int hash_alg; 74 }; 75 static const struct kexalg kexalgs[] = { 76 #ifdef WITH_OPENSSL 77 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 }, 78 { KEX_DH14, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 }, 79 { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 }, 80 #ifdef HAVE_EVP_SHA256 81 { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 }, 82 #endif /* HAVE_EVP_SHA256 */ 83 #ifdef OPENSSL_HAS_ECC 84 { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2, 85 NID_X9_62_prime256v1, SSH_DIGEST_SHA256 }, 86 { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1, 87 SSH_DIGEST_SHA384 }, 88 # ifdef OPENSSL_HAS_NISTP521 89 { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1, 90 SSH_DIGEST_SHA512 }, 91 # endif /* OPENSSL_HAS_NISTP521 */ 92 #endif /* OPENSSL_HAS_ECC */ 93 { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 }, 94 #endif /* WITH_OPENSSL */ 95 #ifdef HAVE_EVP_SHA256 96 { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 }, 97 #endif /* HAVE_EVP_SHA256 */ 98 { NULL, -1, -1, -1}, 99 }; 100 101 char * 102 kex_alg_list(char sep) 103 { 104 char *ret = NULL; 105 size_t nlen, rlen = 0; 106 const struct kexalg *k; 107 108 for (k = kexalgs; k->name != NULL; k++) { 109 if (ret != NULL) 110 ret[rlen++] = sep; 111 nlen = strlen(k->name); 112 ret = xrealloc(ret, 1, rlen + nlen + 2); 113 memcpy(ret + rlen, k->name, nlen + 1); 114 rlen += nlen; 115 } 116 return ret; 117 } 118 119 static const struct kexalg * 120 kex_alg_by_name(const char *name) 121 { 122 const struct kexalg *k; 123 124 for (k = kexalgs; k->name != NULL; k++) { 125 if (strcmp(k->name, name) == 0) 126 return k; 127 } 128 return NULL; 129 } 130 131 /* Validate KEX method name list */ 132 int 133 kex_names_valid(const char *names) 134 { 135 char *s, *cp, *p; 136 137 if (names == NULL || strcmp(names, "") == 0) 138 return 0; 139 s = cp = xstrdup(names); 140 for ((p = strsep(&cp, ",")); p && *p != '\0'; 141 (p = strsep(&cp, ","))) { 142 if (kex_alg_by_name(p) == NULL) { 143 error("Unsupported KEX algorithm \"%.100s\"", p); 144 free(s); 145 return 0; 146 } 147 } 148 debug3("kex names ok: [%s]", names); 149 free(s); 150 return 1; 151 } 152 153 /* put algorithm proposal into buffer */ 154 /* used in sshconnect.c as well as kex.c */ 155 void 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 ** 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 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 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 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 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 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 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 * 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 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 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 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 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 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 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 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 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 int log_flag = 0; 470 int auth_flag; 471 472 auth_flag = packet_authentication_state(); 473 debug ("AUTH STATE IS %d", auth_flag); 474 475 my = kex_buf2prop(&kex->my, NULL); 476 peer = kex_buf2prop(&kex->peer, &first_kex_follows); 477 478 if (kex->server) { 479 cprop=peer; 480 sprop=my; 481 } else { 482 cprop=my; 483 sprop=peer; 484 } 485 486 /* Check whether server offers roaming */ 487 if (!kex->server) { 488 char *roaming; 489 roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL); 490 if (roaming) { 491 kex->roaming = 1; 492 free(roaming); 493 } 494 } 495 496 /* Algorithm Negotiation */ 497 for (mode = 0; mode < MODE_MAX; mode++) { 498 newkeys = xcalloc(1, sizeof(*newkeys)); 499 kex->newkeys[mode] = newkeys; 500 ctos = (!kex->server && mode == MODE_OUT) || 501 (kex->server && mode == MODE_IN); 502 nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; 503 nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; 504 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; 505 choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]); 506 /* ignore mac for authenticated encryption */ 507 authlen = cipher_authlen(newkeys->enc.cipher); 508 if (authlen == 0) 509 choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]); 510 choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); 511 debug("REQUESTED ENC.NAME is '%s'", newkeys->enc.name); 512 if (strcmp(newkeys->enc.name, "none") == 0) { 513 debug("Requesting NONE. Authflag is %d", auth_flag); 514 if (auth_flag == 1) { 515 debug("None requested post authentication."); 516 } else { 517 fatal("Pre-authentication none cipher requests are not allowed."); 518 } 519 } 520 debug("kex: %s %s %s %s", 521 ctos ? "client->server" : "server->client", 522 newkeys->enc.name, 523 authlen == 0 ? newkeys->mac.name : "<implicit>", 524 newkeys->comp.name); 525 /* client starts withctos = 0 && log flag = 0 and no log*/ 526 /* 2nd client pass ctos=1 and flag = 1 so no log*/ 527 /* server starts with ctos =1 && log_flag = 0 so log */ 528 /* 2nd sever pass ctos = 1 && log flag = 1 so no log*/ 529 /* -cjr*/ 530 if (ctos && !log_flag) { 531 logit("SSH: Server;Ltype: Kex;Remote: %s-%d;Enc: %s;MAC: %s;Comp: %s", 532 get_remote_ipaddr(), 533 get_remote_port(), 534 newkeys->enc.name, 535 newkeys->mac.name, 536 newkeys->comp.name); 537 } 538 log_flag = 1; 539 } 540 choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); 541 choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], 542 sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); 543 need = dh_need = 0; 544 for (mode = 0; mode < MODE_MAX; mode++) { 545 newkeys = kex->newkeys[mode]; 546 need = MAX(need, newkeys->enc.key_len); 547 need = MAX(need, newkeys->enc.block_size); 548 need = MAX(need, newkeys->enc.iv_len); 549 need = MAX(need, newkeys->mac.key_len); 550 dh_need = MAX(dh_need, cipher_seclen(newkeys->enc.cipher)); 551 dh_need = MAX(dh_need, newkeys->enc.block_size); 552 dh_need = MAX(dh_need, newkeys->enc.iv_len); 553 dh_need = MAX(dh_need, newkeys->mac.key_len); 554 } 555 /* XXX need runden? */ 556 kex->we_need = need; 557 kex->dh_need = dh_need; 558 559 /* ignore the next message if the proposals do not match */ 560 if (first_kex_follows && !proposals_match(my, peer) && 561 !(datafellows & SSH_BUG_FIRSTKEX)) { 562 type = packet_read(); 563 debug2("skipping next packet (type %u)", type); 564 } 565 566 kex_prop_free(my); 567 kex_prop_free(peer); 568 } 569 570 static u_char * 571 derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, 572 const u_char *shared_secret, u_int slen) 573 { 574 Buffer b; 575 struct ssh_digest_ctx *hashctx; 576 char c = id; 577 u_int have; 578 size_t mdsz; 579 u_char *digest; 580 581 if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0) 582 fatal("bad kex md size %zu", mdsz); 583 digest = xmalloc(roundup(need, mdsz)); 584 585 buffer_init(&b); 586 buffer_append(&b, shared_secret, slen); 587 588 /* K1 = HASH(K || H || "A" || session_id) */ 589 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL) 590 fatal("%s: ssh_digest_start failed", __func__); 591 if (ssh_digest_update_buffer(hashctx, &b) != 0 || 592 ssh_digest_update(hashctx, hash, hashlen) != 0 || 593 ssh_digest_update(hashctx, &c, 1) != 0 || 594 ssh_digest_update(hashctx, kex->session_id, 595 kex->session_id_len) != 0) 596 fatal("%s: ssh_digest_update failed", __func__); 597 if (ssh_digest_final(hashctx, digest, mdsz) != 0) 598 fatal("%s: ssh_digest_final failed", __func__); 599 ssh_digest_free(hashctx); 600 601 /* 602 * expand key: 603 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) 604 * Key = K1 || K2 || ... || Kn 605 */ 606 for (have = mdsz; need > have; have += mdsz) { 607 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL) 608 fatal("%s: ssh_digest_start failed", __func__); 609 if (ssh_digest_update_buffer(hashctx, &b) != 0 || 610 ssh_digest_update(hashctx, hash, hashlen) != 0 || 611 ssh_digest_update(hashctx, digest, have) != 0) 612 fatal("%s: ssh_digest_update failed", __func__); 613 if (ssh_digest_final(hashctx, digest + have, mdsz) != 0) 614 fatal("%s: ssh_digest_final failed", __func__); 615 ssh_digest_free(hashctx); 616 } 617 buffer_free(&b); 618 #ifdef DEBUG_KEX 619 fprintf(stderr, "key '%c'== ", c); 620 dump_digest("key", digest, need); 621 #endif 622 return digest; 623 } 624 625 Newkeys *current_keys[MODE_MAX]; 626 627 #define NKEYS 6 628 void 629 kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, 630 const u_char *shared_secret, u_int slen) 631 { 632 u_char *keys[NKEYS]; 633 u_int i, mode, ctos; 634 635 for (i = 0; i < NKEYS; i++) { 636 keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, 637 shared_secret, slen); 638 } 639 640 debug2("kex_derive_keys"); 641 for (mode = 0; mode < MODE_MAX; mode++) { 642 current_keys[mode] = kex->newkeys[mode]; 643 kex->newkeys[mode] = NULL; 644 ctos = (!kex->server && mode == MODE_OUT) || 645 (kex->server && mode == MODE_IN); 646 current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; 647 current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; 648 current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; 649 } 650 } 651 652 #ifdef WITH_OPENSSL 653 void 654 kex_derive_keys_bn(Kex *kex, u_char *hash, u_int hashlen, const BIGNUM *secret) 655 { 656 Buffer shared_secret; 657 658 buffer_init(&shared_secret); 659 buffer_put_bignum2(&shared_secret, secret); 660 kex_derive_keys(kex, hash, hashlen, 661 buffer_ptr(&shared_secret), buffer_len(&shared_secret)); 662 buffer_free(&shared_secret); 663 } 664 #endif 665 666 Newkeys * 667 kex_get_newkeys(int mode) 668 { 669 Newkeys *ret; 670 671 ret = current_keys[mode]; 672 current_keys[mode] = NULL; 673 return ret; 674 } 675 676 #ifdef WITH_SSH1 677 void 678 derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, 679 u_int8_t cookie[8], u_int8_t id[16]) 680 { 681 u_int8_t nbuf[2048], obuf[SSH_DIGEST_MAX_LENGTH]; 682 int len; 683 struct ssh_digest_ctx *hashctx; 684 685 if ((hashctx = ssh_digest_start(SSH_DIGEST_MD5)) == NULL) 686 fatal("%s: ssh_digest_start", __func__); 687 688 len = BN_num_bytes(host_modulus); 689 if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 690 fatal("%s: bad host modulus (len %d)", __func__, len); 691 BN_bn2bin(host_modulus, nbuf); 692 if (ssh_digest_update(hashctx, nbuf, len) != 0) 693 fatal("%s: ssh_digest_update failed", __func__); 694 695 len = BN_num_bytes(server_modulus); 696 if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 697 fatal("%s: bad server modulus (len %d)", __func__, len); 698 BN_bn2bin(server_modulus, nbuf); 699 if (ssh_digest_update(hashctx, nbuf, len) != 0 || 700 ssh_digest_update(hashctx, cookie, 8) != 0) 701 fatal("%s: ssh_digest_update failed", __func__); 702 if (ssh_digest_final(hashctx, obuf, sizeof(obuf)) != 0) 703 fatal("%s: ssh_digest_final failed", __func__); 704 memcpy(id, obuf, ssh_digest_bytes(SSH_DIGEST_MD5)); 705 706 explicit_bzero(nbuf, sizeof(nbuf)); 707 explicit_bzero(obuf, sizeof(obuf)); 708 } 709 #endif 710 711 #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 712 void 713 dump_digest(char *msg, u_char *digest, int len) 714 { 715 int i; 716 717 fprintf(stderr, "%s\n", msg); 718 for (i = 0; i < len; i++) { 719 fprintf(stderr, "%02x", digest[i]); 720 if (i%32 == 31) 721 fprintf(stderr, "\n"); 722 else if (i%8 == 7) 723 fprintf(stderr, " "); 724 } 725 fprintf(stderr, "\n"); 726 } 727 #endif 728