kex.c revision 263691
1230557Sjimharris/* $OpenBSD: kex.c,v 1.97 2014/01/25 20:35:37 markus Exp $ */ 2230557Sjimharris/* $FreeBSD: head/crypto/openssh/kex.c 263691 2014-03-24 19:15:13Z des $ */ 3230557Sjimharris/* 4230557Sjimharris * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. 5230557Sjimharris * 6230557Sjimharris * Redistribution and use in source and binary forms, with or without 7230557Sjimharris * modification, are permitted provided that the following conditions 8230557Sjimharris * are met: 9230557Sjimharris * 1. Redistributions of source code must retain the above copyright 10230557Sjimharris * notice, this list of conditions and the following disclaimer. 11230557Sjimharris * 2. Redistributions in binary form must reproduce the above copyright 12230557Sjimharris * notice, this list of conditions and the following disclaimer in the 13230557Sjimharris * documentation and/or other materials provided with the distribution. 14230557Sjimharris * 15230557Sjimharris * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16230557Sjimharris * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17230557Sjimharris * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18230557Sjimharris * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19230557Sjimharris * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20230557Sjimharris * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21230557Sjimharris * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22230557Sjimharris * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23230557Sjimharris * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24230557Sjimharris * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25230557Sjimharris */ 26230557Sjimharris 27230557Sjimharris#include "includes.h" 28230557Sjimharris__RCSID("$FreeBSD: head/crypto/openssh/kex.c 263691 2014-03-24 19:15:13Z des $"); 29230557Sjimharris 30230557Sjimharris#include <sys/param.h> 31230557Sjimharris 32230557Sjimharris#include <signal.h> 33230557Sjimharris#include <stdarg.h> 34230557Sjimharris#include <stdio.h> 35230557Sjimharris#include <stdlib.h> 36230557Sjimharris#include <string.h> 37230557Sjimharris 38230557Sjimharris#include <openssl/crypto.h> 39230557Sjimharris 40230557Sjimharris#include "xmalloc.h" 41230557Sjimharris#include "ssh2.h" 42230557Sjimharris#include "buffer.h" 43230557Sjimharris#include "packet.h" 44230557Sjimharris#include "compat.h" 45230557Sjimharris#include "cipher.h" 46230557Sjimharris#include "key.h" 47230557Sjimharris#include "kex.h" 48230557Sjimharris#include "log.h" 49230557Sjimharris#include "mac.h" 50230557Sjimharris#include "match.h" 51230557Sjimharris#include "dispatch.h" 52230557Sjimharris#include "monitor.h" 53230557Sjimharris#include "roaming.h" 54230557Sjimharris#include "digest.h" 55230557Sjimharris 56230557Sjimharris#if OPENSSL_VERSION_NUMBER >= 0x00907000L 57230557Sjimharris# if defined(HAVE_EVP_SHA256) 58230557Sjimharris# define evp_ssh_sha256 EVP_sha256 59230557Sjimharris# else 60230557Sjimharrisextern const EVP_MD *evp_ssh_sha256(void); 61230557Sjimharris# endif 62230557Sjimharris#endif 63230557Sjimharris 64230557Sjimharris/* prototype */ 65230557Sjimharrisstatic void kex_kexinit_finish(Kex *); 66230557Sjimharrisstatic void kex_choose_conf(Kex *); 67230557Sjimharris 68230557Sjimharrisstruct kexalg { 69230557Sjimharris char *name; 70230557Sjimharris int type; 71230557Sjimharris int ec_nid; 72230557Sjimharris int hash_alg; 73230557Sjimharris}; 74230557Sjimharrisstatic const struct kexalg kexalgs[] = { 75230557Sjimharris { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 }, 76230557Sjimharris { KEX_DH14, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 }, 77230557Sjimharris { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 }, 78230557Sjimharris#ifdef HAVE_EVP_SHA256 79230557Sjimharris { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 }, 80230557Sjimharris#endif 81230557Sjimharris#ifdef OPENSSL_HAS_ECC 82230557Sjimharris { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2, 83230557Sjimharris NID_X9_62_prime256v1, SSH_DIGEST_SHA256 }, 84230557Sjimharris { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1, 85230557Sjimharris SSH_DIGEST_SHA384 }, 86230557Sjimharris# ifdef OPENSSL_HAS_NISTP521 87230557Sjimharris { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1, 88230557Sjimharris SSH_DIGEST_SHA512 }, 89230557Sjimharris# endif 90230557Sjimharris#endif 91230557Sjimharris { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 }, 92230557Sjimharris#ifdef HAVE_EVP_SHA256 93230557Sjimharris { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 }, 94230557Sjimharris#endif 95230557Sjimharris { NULL, -1, -1, -1}, 96230557Sjimharris}; 97230557Sjimharris 98230557Sjimharrischar * 99230557Sjimharriskex_alg_list(char sep) 100230557Sjimharris{ 101230557Sjimharris char *ret = NULL; 102230557Sjimharris size_t nlen, rlen = 0; 103230557Sjimharris const struct kexalg *k; 104230557Sjimharris 105230557Sjimharris for (k = kexalgs; k->name != NULL; k++) { 106230557Sjimharris if (ret != NULL) 107230557Sjimharris ret[rlen++] = sep; 108230557Sjimharris nlen = strlen(k->name); 109230557Sjimharris ret = xrealloc(ret, 1, rlen + nlen + 2); 110230557Sjimharris memcpy(ret + rlen, k->name, nlen + 1); 111230557Sjimharris rlen += nlen; 112230557Sjimharris } 113230557Sjimharris return ret; 114230557Sjimharris} 115230557Sjimharris 116230557Sjimharrisstatic const struct kexalg * 117230557Sjimharriskex_alg_by_name(const char *name) 118230557Sjimharris{ 119230557Sjimharris const struct kexalg *k; 120230557Sjimharris 121230557Sjimharris for (k = kexalgs; k->name != NULL; k++) { 122230557Sjimharris if (strcmp(k->name, name) == 0) 123230557Sjimharris return k; 124230557Sjimharris } 125230557Sjimharris return NULL; 126230557Sjimharris} 127230557Sjimharris 128230557Sjimharris/* Validate KEX method name list */ 129230557Sjimharrisint 130230557Sjimharriskex_names_valid(const char *names) 131230557Sjimharris{ 132230557Sjimharris char *s, *cp, *p; 133230557Sjimharris 134230557Sjimharris if (names == NULL || strcmp(names, "") == 0) 135230557Sjimharris return 0; 136230557Sjimharris s = cp = xstrdup(names); 137230557Sjimharris for ((p = strsep(&cp, ",")); p && *p != '\0'; 138230557Sjimharris (p = strsep(&cp, ","))) { 139230557Sjimharris if (kex_alg_by_name(p) == NULL) { 140230557Sjimharris error("Unsupported KEX algorithm \"%.100s\"", p); 141230557Sjimharris free(s); 142230557Sjimharris return 0; 143230557Sjimharris } 144230557Sjimharris } 145230557Sjimharris debug3("kex names ok: [%s]", names); 146230557Sjimharris free(s); 147230557Sjimharris return 1; 148230557Sjimharris} 149230557Sjimharris 150230557Sjimharris/* put algorithm proposal into buffer. */ 151230557Sjimharris#ifndef NONE_CIPHER_ENABLED 152230557Sjimharrisstatic void 153230557Sjimharris#else 154230557Sjimharris/* Also used in sshconnect2.c. */ 155230557Sjimharrisvoid 156230557Sjimharris#endif 157230557Sjimharriskex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) 158230557Sjimharris{ 159230557Sjimharris u_int i; 160230557Sjimharris 161230557Sjimharris buffer_clear(b); 162230557Sjimharris /* 163230557Sjimharris * add a dummy cookie, the cookie will be overwritten by 164230557Sjimharris * kex_send_kexinit(), each time a kexinit is set 165230557Sjimharris */ 166230557Sjimharris for (i = 0; i < KEX_COOKIE_LEN; i++) 167230557Sjimharris buffer_put_char(b, 0); 168230557Sjimharris for (i = 0; i < PROPOSAL_MAX; i++) 169230557Sjimharris buffer_put_cstring(b, proposal[i]); 170230557Sjimharris buffer_put_char(b, 0); /* first_kex_packet_follows */ 171230557Sjimharris buffer_put_int(b, 0); /* uint32 reserved */ 172230557Sjimharris} 173230557Sjimharris 174230557Sjimharris/* parse buffer and return algorithm proposal */ 175230557Sjimharrisstatic char ** 176230557Sjimharriskex_buf2prop(Buffer *raw, int *first_kex_follows) 177230557Sjimharris{ 178230557Sjimharris Buffer b; 179230557Sjimharris u_int i; 180230557Sjimharris char **proposal; 181230557Sjimharris 182230557Sjimharris proposal = xcalloc(PROPOSAL_MAX, sizeof(char *)); 183230557Sjimharris 184230557Sjimharris buffer_init(&b); 185230557Sjimharris buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); 186230557Sjimharris /* skip cookie */ 187230557Sjimharris for (i = 0; i < KEX_COOKIE_LEN; i++) 188230557Sjimharris buffer_get_char(&b); 189230557Sjimharris /* extract kex init proposal strings */ 190230557Sjimharris for (i = 0; i < PROPOSAL_MAX; i++) { 191230557Sjimharris proposal[i] = buffer_get_cstring(&b,NULL); 192230557Sjimharris debug2("kex_parse_kexinit: %s", proposal[i]); 193230557Sjimharris } 194230557Sjimharris /* first kex follows / reserved */ 195230557Sjimharris i = buffer_get_char(&b); 196230557Sjimharris if (first_kex_follows != NULL) 197230557Sjimharris *first_kex_follows = i; 198230557Sjimharris debug2("kex_parse_kexinit: first_kex_follows %d ", i); 199230557Sjimharris i = buffer_get_int(&b); 200230557Sjimharris debug2("kex_parse_kexinit: reserved %u ", i); 201230557Sjimharris buffer_free(&b); 202230557Sjimharris return proposal; 203230557Sjimharris} 204230557Sjimharris 205230557Sjimharrisstatic void 206230557Sjimharriskex_prop_free(char **proposal) 207230557Sjimharris{ 208230557Sjimharris u_int i; 209230557Sjimharris 210230557Sjimharris for (i = 0; i < PROPOSAL_MAX; i++) 211230557Sjimharris free(proposal[i]); 212230557Sjimharris free(proposal); 213230557Sjimharris} 214230557Sjimharris 215230557Sjimharris/* ARGSUSED */ 216230557Sjimharrisstatic void 217230557Sjimharriskex_protocol_error(int type, u_int32_t seq, void *ctxt) 218230557Sjimharris{ 219230557Sjimharris error("Hm, kex protocol error: type %d seq %u", type, seq); 220230557Sjimharris} 221230557Sjimharris 222230557Sjimharrisstatic void 223230557Sjimharriskex_reset_dispatch(void) 224230557Sjimharris{ 225230557Sjimharris dispatch_range(SSH2_MSG_TRANSPORT_MIN, 226230557Sjimharris SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); 227230557Sjimharris dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); 228230557Sjimharris} 229230557Sjimharris 230230557Sjimharrisvoid 231230557Sjimharriskex_finish(Kex *kex) 232230557Sjimharris{ 233230557Sjimharris kex_reset_dispatch(); 234230557Sjimharris 235230557Sjimharris packet_start(SSH2_MSG_NEWKEYS); 236230557Sjimharris packet_send(); 237230557Sjimharris /* packet_write_wait(); */ 238230557Sjimharris debug("SSH2_MSG_NEWKEYS sent"); 239230557Sjimharris 240230557Sjimharris debug("expecting SSH2_MSG_NEWKEYS"); 241230557Sjimharris packet_read_expect(SSH2_MSG_NEWKEYS); 242230557Sjimharris packet_check_eom(); 243230557Sjimharris debug("SSH2_MSG_NEWKEYS received"); 244230557Sjimharris 245230557Sjimharris kex->done = 1; 246230557Sjimharris buffer_clear(&kex->peer); 247230557Sjimharris /* buffer_clear(&kex->my); */ 248230557Sjimharris kex->flags &= ~KEX_INIT_SENT; 249230557Sjimharris free(kex->name); 250230557Sjimharris kex->name = NULL; 251230557Sjimharris} 252230557Sjimharris 253230557Sjimharrisvoid 254230557Sjimharriskex_send_kexinit(Kex *kex) 255230557Sjimharris{ 256230557Sjimharris u_int32_t rnd = 0; 257230557Sjimharris u_char *cookie; 258230557Sjimharris u_int i; 259230557Sjimharris 260230557Sjimharris if (kex == NULL) { 261230557Sjimharris error("kex_send_kexinit: no kex, cannot rekey"); 262230557Sjimharris return; 263230557Sjimharris } 264230557Sjimharris if (kex->flags & KEX_INIT_SENT) { 265230557Sjimharris debug("KEX_INIT_SENT"); 266230557Sjimharris return; 267230557Sjimharris } 268230557Sjimharris kex->done = 0; 269230557Sjimharris 270230557Sjimharris /* generate a random cookie */ 271230557Sjimharris if (buffer_len(&kex->my) < KEX_COOKIE_LEN) 272230557Sjimharris fatal("kex_send_kexinit: kex proposal too short"); 273230557Sjimharris cookie = buffer_ptr(&kex->my); 274230557Sjimharris for (i = 0; i < KEX_COOKIE_LEN; i++) { 275230557Sjimharris if (i % 4 == 0) 276230557Sjimharris rnd = arc4random(); 277230557Sjimharris cookie[i] = rnd; 278230557Sjimharris rnd >>= 8; 279230557Sjimharris } 280230557Sjimharris packet_start(SSH2_MSG_KEXINIT); 281230557Sjimharris packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); 282230557Sjimharris packet_send(); 283230557Sjimharris debug("SSH2_MSG_KEXINIT sent"); 284230557Sjimharris kex->flags |= KEX_INIT_SENT; 285230557Sjimharris} 286230557Sjimharris 287230557Sjimharris/* ARGSUSED */ 288230557Sjimharrisvoid 289230557Sjimharriskex_input_kexinit(int type, u_int32_t seq, void *ctxt) 290230557Sjimharris{ 291230557Sjimharris char *ptr; 292230557Sjimharris u_int i, dlen; 293230557Sjimharris Kex *kex = (Kex *)ctxt; 294230557Sjimharris 295230557Sjimharris debug("SSH2_MSG_KEXINIT received"); 296230557Sjimharris if (kex == NULL) 297230557Sjimharris fatal("kex_input_kexinit: no kex, cannot rekey"); 298230557Sjimharris 299230557Sjimharris ptr = packet_get_raw(&dlen); 300230557Sjimharris buffer_append(&kex->peer, ptr, dlen); 301230557Sjimharris 302230557Sjimharris /* discard packet */ 303230557Sjimharris for (i = 0; i < KEX_COOKIE_LEN; i++) 304230557Sjimharris packet_get_char(); 305230557Sjimharris for (i = 0; i < PROPOSAL_MAX; i++) 306 free(packet_get_string(NULL)); 307 /* 308 * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported 309 * KEX method has the server move first, but a server might be using 310 * a custom method or one that we otherwise don't support. We should 311 * be prepared to remember first_kex_follows here so we can eat a 312 * packet later. 313 * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means 314 * for cases where the server *doesn't* go first. I guess we should 315 * ignore it when it is set for these cases, which is what we do now. 316 */ 317 (void) packet_get_char(); /* first_kex_follows */ 318 (void) packet_get_int(); /* reserved */ 319 packet_check_eom(); 320 321 kex_kexinit_finish(kex); 322} 323 324Kex * 325kex_setup(char *proposal[PROPOSAL_MAX]) 326{ 327 Kex *kex; 328 329 kex = xcalloc(1, sizeof(*kex)); 330 buffer_init(&kex->peer); 331 buffer_init(&kex->my); 332 kex_prop2buf(&kex->my, proposal); 333 kex->done = 0; 334 335 kex_send_kexinit(kex); /* we start */ 336 kex_reset_dispatch(); 337 338 return kex; 339} 340 341static void 342kex_kexinit_finish(Kex *kex) 343{ 344 if (!(kex->flags & KEX_INIT_SENT)) 345 kex_send_kexinit(kex); 346 347 kex_choose_conf(kex); 348 349 if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX && 350 kex->kex[kex->kex_type] != NULL) { 351 (kex->kex[kex->kex_type])(kex); 352 } else { 353 fatal("Unsupported key exchange %d", kex->kex_type); 354 } 355} 356 357static void 358choose_enc(Enc *enc, char *client, char *server) 359{ 360 char *name = match_list(client, server, NULL); 361 if (name == NULL) 362 fatal("no matching cipher found: client %s server %s", 363 client, server); 364 if ((enc->cipher = cipher_by_name(name)) == NULL) 365 fatal("matching cipher is not supported: %s", name); 366 enc->name = name; 367 enc->enabled = 0; 368 enc->iv = NULL; 369 enc->iv_len = cipher_ivlen(enc->cipher); 370 enc->key = NULL; 371 enc->key_len = cipher_keylen(enc->cipher); 372 enc->block_size = cipher_blocksize(enc->cipher); 373} 374 375static void 376choose_mac(Mac *mac, char *client, char *server) 377{ 378 char *name = match_list(client, server, NULL); 379 if (name == NULL) 380 fatal("no matching mac found: client %s server %s", 381 client, server); 382 if (mac_setup(mac, name) < 0) 383 fatal("unsupported mac %s", name); 384 /* truncate the key */ 385 if (datafellows & SSH_BUG_HMAC) 386 mac->key_len = 16; 387 mac->name = name; 388 mac->key = NULL; 389 mac->enabled = 0; 390} 391 392static void 393choose_comp(Comp *comp, char *client, char *server) 394{ 395 char *name = match_list(client, server, NULL); 396 if (name == NULL) 397 fatal("no matching comp found: client %s server %s", client, server); 398 if (strcmp(name, "zlib@openssh.com") == 0) { 399 comp->type = COMP_DELAYED; 400 } else if (strcmp(name, "zlib") == 0) { 401 comp->type = COMP_ZLIB; 402 } else if (strcmp(name, "none") == 0) { 403 comp->type = COMP_NONE; 404 } else { 405 fatal("unsupported comp %s", name); 406 } 407 comp->name = name; 408} 409 410static void 411choose_kex(Kex *k, char *client, char *server) 412{ 413 const struct kexalg *kexalg; 414 415 k->name = match_list(client, server, NULL); 416 if (k->name == NULL) 417 fatal("Unable to negotiate a key exchange method"); 418 if ((kexalg = kex_alg_by_name(k->name)) == NULL) 419 fatal("unsupported kex alg %s", k->name); 420 k->kex_type = kexalg->type; 421 k->hash_alg = kexalg->hash_alg; 422 k->ec_nid = kexalg->ec_nid; 423} 424 425static void 426choose_hostkeyalg(Kex *k, char *client, char *server) 427{ 428 char *hostkeyalg = match_list(client, server, NULL); 429 if (hostkeyalg == NULL) 430 fatal("no hostkey alg"); 431 k->hostkey_type = key_type_from_name(hostkeyalg); 432 if (k->hostkey_type == KEY_UNSPEC) 433 fatal("bad hostkey alg '%s'", hostkeyalg); 434 free(hostkeyalg); 435} 436 437static int 438proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) 439{ 440 static int check[] = { 441 PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 442 }; 443 int *idx; 444 char *p; 445 446 for (idx = &check[0]; *idx != -1; idx++) { 447 if ((p = strchr(my[*idx], ',')) != NULL) 448 *p = '\0'; 449 if ((p = strchr(peer[*idx], ',')) != NULL) 450 *p = '\0'; 451 if (strcmp(my[*idx], peer[*idx]) != 0) { 452 debug2("proposal mismatch: my %s peer %s", 453 my[*idx], peer[*idx]); 454 return (0); 455 } 456 } 457 debug2("proposals match"); 458 return (1); 459} 460 461static void 462kex_choose_conf(Kex *kex) 463{ 464 Newkeys *newkeys; 465 char **my, **peer; 466 char **cprop, **sprop; 467 int nenc, nmac, ncomp; 468 u_int mode, ctos, need, dh_need, authlen; 469 int first_kex_follows, type; 470#ifdef NONE_CIPHER_ENABLED 471 int auth_flag; 472#endif 473 474 my = kex_buf2prop(&kex->my, NULL); 475 peer = kex_buf2prop(&kex->peer, &first_kex_follows); 476 477 if (kex->server) { 478 cprop=peer; 479 sprop=my; 480 } else { 481 cprop=my; 482 sprop=peer; 483 } 484 485 /* Check whether server offers roaming */ 486 if (!kex->server) { 487 char *roaming; 488 roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL); 489 if (roaming) { 490 kex->roaming = 1; 491 free(roaming); 492 } 493 } 494 495 /* Algorithm Negotiation */ 496#ifdef NONE_CIPHER_ENABLED 497 auth_flag = packet_get_authentication_state(); 498 debug ("AUTH STATE is %d", auth_flag); 499#endif 500 for (mode = 0; mode < MODE_MAX; mode++) { 501 newkeys = xcalloc(1, sizeof(*newkeys)); 502 kex->newkeys[mode] = newkeys; 503 ctos = (!kex->server && mode == MODE_OUT) || 504 (kex->server && mode == MODE_IN); 505 nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; 506 nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; 507 ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; 508 choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]); 509 /* ignore mac for authenticated encryption */ 510 authlen = cipher_authlen(newkeys->enc.cipher); 511 if (authlen == 0) 512 choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]); 513 choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); 514#ifdef NONE_CIPHER_ENABLED 515 debug("REQUESTED ENC.NAME is '%s'", newkeys->enc.name); 516 if (strcmp(newkeys->enc.name, "none") == 0) { 517 debug("Requesting NONE. Authflag is %d", auth_flag); 518 if (auth_flag == 1) 519 debug("None requested post authentication."); 520 else 521 fatal("Pre-authentication none cipher requests " 522 "are not allowed."); 523 } 524#endif 525 debug("kex: %s %s %s %s", 526 ctos ? "client->server" : "server->client", 527 newkeys->enc.name, 528 authlen == 0 ? newkeys->mac.name : "<implicit>", 529 newkeys->comp.name); 530 } 531 choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); 532 choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], 533 sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); 534 need = dh_need = 0; 535 for (mode = 0; mode < MODE_MAX; mode++) { 536 newkeys = kex->newkeys[mode]; 537 need = MAX(need, newkeys->enc.key_len); 538 need = MAX(need, newkeys->enc.block_size); 539 need = MAX(need, newkeys->enc.iv_len); 540 need = MAX(need, newkeys->mac.key_len); 541 dh_need = MAX(dh_need, cipher_seclen(newkeys->enc.cipher)); 542 dh_need = MAX(dh_need, newkeys->enc.block_size); 543 dh_need = MAX(dh_need, newkeys->enc.iv_len); 544 dh_need = MAX(dh_need, newkeys->mac.key_len); 545 } 546 /* XXX need runden? */ 547 kex->we_need = need; 548 kex->dh_need = dh_need; 549 550 /* ignore the next message if the proposals do not match */ 551 if (first_kex_follows && !proposals_match(my, peer) && 552 !(datafellows & SSH_BUG_FIRSTKEX)) { 553 type = packet_read(); 554 debug2("skipping next packet (type %u)", type); 555 } 556 557 kex_prop_free(my); 558 kex_prop_free(peer); 559} 560 561static u_char * 562derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, 563 const u_char *shared_secret, u_int slen) 564{ 565 Buffer b; 566 struct ssh_digest_ctx *hashctx; 567 char c = id; 568 u_int have; 569 size_t mdsz; 570 u_char *digest; 571 572 if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0) 573 fatal("bad kex md size %zu", mdsz); 574 digest = xmalloc(roundup(need, mdsz)); 575 576 buffer_init(&b); 577 buffer_append(&b, shared_secret, slen); 578 579 /* K1 = HASH(K || H || "A" || session_id) */ 580 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL) 581 fatal("%s: ssh_digest_start failed", __func__); 582 if (ssh_digest_update_buffer(hashctx, &b) != 0 || 583 ssh_digest_update(hashctx, hash, hashlen) != 0 || 584 ssh_digest_update(hashctx, &c, 1) != 0 || 585 ssh_digest_update(hashctx, kex->session_id, 586 kex->session_id_len) != 0) 587 fatal("%s: ssh_digest_update failed", __func__); 588 if (ssh_digest_final(hashctx, digest, mdsz) != 0) 589 fatal("%s: ssh_digest_final failed", __func__); 590 ssh_digest_free(hashctx); 591 592 /* 593 * expand key: 594 * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) 595 * Key = K1 || K2 || ... || Kn 596 */ 597 for (have = mdsz; need > have; have += mdsz) { 598 if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL) 599 fatal("%s: ssh_digest_start failed", __func__); 600 if (ssh_digest_update_buffer(hashctx, &b) != 0 || 601 ssh_digest_update(hashctx, hash, hashlen) != 0 || 602 ssh_digest_update(hashctx, digest, have) != 0) 603 fatal("%s: ssh_digest_update failed", __func__); 604 if (ssh_digest_final(hashctx, digest + have, mdsz) != 0) 605 fatal("%s: ssh_digest_final failed", __func__); 606 ssh_digest_free(hashctx); 607 } 608 buffer_free(&b); 609#ifdef DEBUG_KEX 610 fprintf(stderr, "key '%c'== ", c); 611 dump_digest("key", digest, need); 612#endif 613 return digest; 614} 615 616Newkeys *current_keys[MODE_MAX]; 617 618#define NKEYS 6 619void 620kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, 621 const u_char *shared_secret, u_int slen) 622{ 623 u_char *keys[NKEYS]; 624 u_int i, mode, ctos; 625 626 for (i = 0; i < NKEYS; i++) { 627 keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, 628 shared_secret, slen); 629 } 630 631 debug2("kex_derive_keys"); 632 for (mode = 0; mode < MODE_MAX; mode++) { 633 current_keys[mode] = kex->newkeys[mode]; 634 kex->newkeys[mode] = NULL; 635 ctos = (!kex->server && mode == MODE_OUT) || 636 (kex->server && mode == MODE_IN); 637 current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; 638 current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; 639 current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; 640 } 641} 642 643void 644kex_derive_keys_bn(Kex *kex, u_char *hash, u_int hashlen, const BIGNUM *secret) 645{ 646 Buffer shared_secret; 647 648 buffer_init(&shared_secret); 649 buffer_put_bignum2(&shared_secret, secret); 650 kex_derive_keys(kex, hash, hashlen, 651 buffer_ptr(&shared_secret), buffer_len(&shared_secret)); 652 buffer_free(&shared_secret); 653} 654 655Newkeys * 656kex_get_newkeys(int mode) 657{ 658 Newkeys *ret; 659 660 ret = current_keys[mode]; 661 current_keys[mode] = NULL; 662 return ret; 663} 664 665void 666derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, 667 u_int8_t cookie[8], u_int8_t id[16]) 668{ 669 u_int8_t nbuf[2048], obuf[SSH_DIGEST_MAX_LENGTH]; 670 int len; 671 struct ssh_digest_ctx *hashctx; 672 673 if ((hashctx = ssh_digest_start(SSH_DIGEST_MD5)) == NULL) 674 fatal("%s: ssh_digest_start", __func__); 675 676 len = BN_num_bytes(host_modulus); 677 if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 678 fatal("%s: bad host modulus (len %d)", __func__, len); 679 BN_bn2bin(host_modulus, nbuf); 680 if (ssh_digest_update(hashctx, nbuf, len) != 0) 681 fatal("%s: ssh_digest_update failed", __func__); 682 683 len = BN_num_bytes(server_modulus); 684 if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) 685 fatal("%s: bad server modulus (len %d)", __func__, len); 686 BN_bn2bin(server_modulus, nbuf); 687 if (ssh_digest_update(hashctx, nbuf, len) != 0 || 688 ssh_digest_update(hashctx, cookie, 8) != 0) 689 fatal("%s: ssh_digest_update failed", __func__); 690 if (ssh_digest_final(hashctx, obuf, sizeof(obuf)) != 0) 691 fatal("%s: ssh_digest_final failed", __func__); 692 memcpy(id, obuf, ssh_digest_bytes(SSH_DIGEST_MD5)); 693 694 memset(nbuf, 0, sizeof(nbuf)); 695 memset(obuf, 0, sizeof(obuf)); 696} 697 698#if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) 699void 700dump_digest(char *msg, u_char *digest, int len) 701{ 702 int i; 703 704 fprintf(stderr, "%s\n", msg); 705 for (i = 0; i < len; i++) { 706 fprintf(stderr, "%02x", digest[i]); 707 if (i%32 == 31) 708 fprintf(stderr, "\n"); 709 else if (i%8 == 7) 710 fprintf(stderr, " "); 711 } 712 fprintf(stderr, "\n"); 713} 714#endif 715