Mike Lockwood | 1305e95 | 2011-12-07 08:17:59 -0800 | [diff] [blame] | 1 | /* $OpenBSD: kex.c,v 1.86 2010/09/22 05:01:29 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 | |
| 53 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L |
| 54 | # if defined(HAVE_EVP_SHA256) |
| 55 | # define evp_ssh_sha256 EVP_sha256 |
| 56 | # else |
| 57 | extern const EVP_MD *evp_ssh_sha256(void); |
| 58 | # endif |
| 59 | #endif |
| 60 | |
| 61 | /* prototype */ |
| 62 | static void kex_kexinit_finish(Kex *); |
| 63 | static void kex_choose_conf(Kex *); |
| 64 | |
| 65 | /* Validate KEX method name list */ |
| 66 | int |
| 67 | kex_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 | |
| 93 | /* put algorithm proposal into buffer */ |
| 94 | static void |
| 95 | kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) |
| 96 | { |
| 97 | u_int i; |
| 98 | |
| 99 | buffer_clear(b); |
| 100 | /* |
| 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); |
| 106 | for (i = 0; i < PROPOSAL_MAX; i++) |
| 107 | buffer_put_cstring(b, proposal[i]); |
| 108 | buffer_put_char(b, 0); /* first_kex_packet_follows */ |
| 109 | buffer_put_int(b, 0); /* uint32 reserved */ |
| 110 | } |
| 111 | |
| 112 | /* parse buffer and return algorithm proposal */ |
| 113 | static char ** |
| 114 | kex_buf2prop(Buffer *raw, int *first_kex_follows) |
| 115 | { |
| 116 | Buffer b; |
| 117 | u_int i; |
| 118 | char **proposal; |
| 119 | |
| 120 | proposal = xcalloc(PROPOSAL_MAX, sizeof(char *)); |
| 121 | |
| 122 | buffer_init(&b); |
| 123 | buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); |
| 124 | /* skip cookie */ |
| 125 | for (i = 0; i < KEX_COOKIE_LEN; i++) |
| 126 | buffer_get_char(&b); |
| 127 | /* extract kex init proposal strings */ |
| 128 | for (i = 0; i < PROPOSAL_MAX; i++) { |
| 129 | proposal[i] = buffer_get_cstring(&b,NULL); |
| 130 | debug2("kex_parse_kexinit: %s", proposal[i]); |
| 131 | } |
| 132 | /* first kex follows / reserved */ |
| 133 | i = buffer_get_char(&b); |
| 134 | if (first_kex_follows != NULL) |
| 135 | *first_kex_follows = i; |
| 136 | debug2("kex_parse_kexinit: first_kex_follows %d ", i); |
| 137 | i = buffer_get_int(&b); |
| 138 | debug2("kex_parse_kexinit: reserved %u ", i); |
| 139 | buffer_free(&b); |
| 140 | return proposal; |
| 141 | } |
| 142 | |
| 143 | static void |
| 144 | kex_prop_free(char **proposal) |
| 145 | { |
| 146 | u_int i; |
| 147 | |
| 148 | for (i = 0; i < PROPOSAL_MAX; i++) |
| 149 | xfree(proposal[i]); |
| 150 | xfree(proposal); |
| 151 | } |
| 152 | |
| 153 | /* ARGSUSED */ |
| 154 | static void |
| 155 | kex_protocol_error(int type, u_int32_t seq, void *ctxt) |
| 156 | { |
| 157 | error("Hm, kex protocol error: type %d seq %u", type, seq); |
| 158 | } |
| 159 | |
| 160 | static void |
| 161 | kex_reset_dispatch(void) |
| 162 | { |
| 163 | dispatch_range(SSH2_MSG_TRANSPORT_MIN, |
| 164 | SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); |
| 165 | dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); |
| 166 | } |
| 167 | |
| 168 | void |
| 169 | kex_finish(Kex *kex) |
| 170 | { |
| 171 | kex_reset_dispatch(); |
| 172 | |
| 173 | packet_start(SSH2_MSG_NEWKEYS); |
| 174 | packet_send(); |
| 175 | /* packet_write_wait(); */ |
| 176 | debug("SSH2_MSG_NEWKEYS sent"); |
| 177 | |
| 178 | debug("expecting SSH2_MSG_NEWKEYS"); |
| 179 | packet_read_expect(SSH2_MSG_NEWKEYS); |
| 180 | packet_check_eom(); |
| 181 | debug("SSH2_MSG_NEWKEYS received"); |
| 182 | |
| 183 | kex->done = 1; |
| 184 | buffer_clear(&kex->peer); |
| 185 | /* buffer_clear(&kex->my); */ |
| 186 | kex->flags &= ~KEX_INIT_SENT; |
| 187 | xfree(kex->name); |
| 188 | kex->name = NULL; |
| 189 | } |
| 190 | |
| 191 | void |
| 192 | kex_send_kexinit(Kex *kex) |
| 193 | { |
| 194 | u_int32_t rnd = 0; |
| 195 | u_char *cookie; |
| 196 | u_int i; |
| 197 | |
| 198 | if (kex == NULL) { |
| 199 | error("kex_send_kexinit: no kex, cannot rekey"); |
| 200 | return; |
| 201 | } |
| 202 | if (kex->flags & KEX_INIT_SENT) { |
| 203 | debug("KEX_INIT_SENT"); |
| 204 | return; |
| 205 | } |
| 206 | kex->done = 0; |
| 207 | |
| 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) |
| 214 | rnd = arc4random(); |
| 215 | cookie[i] = rnd; |
| 216 | rnd >>= 8; |
| 217 | } |
| 218 | 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 | |
| 225 | /* ARGSUSED */ |
| 226 | void |
| 227 | kex_input_kexinit(int type, u_int32_t seq, void *ctxt) |
| 228 | { |
| 229 | char *ptr; |
| 230 | u_int i, dlen; |
| 231 | Kex *kex = (Kex *)ctxt; |
| 232 | |
| 233 | debug("SSH2_MSG_KEXINIT received"); |
| 234 | if (kex == NULL) |
| 235 | fatal("kex_input_kexinit: no kex, cannot rekey"); |
| 236 | |
| 237 | ptr = packet_get_raw(&dlen); |
| 238 | buffer_append(&kex->peer, ptr, dlen); |
| 239 | |
| 240 | /* 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)); |
| 245 | (void) packet_get_char(); |
| 246 | (void) packet_get_int(); |
| 247 | packet_check_eom(); |
| 248 | |
| 249 | kex_kexinit_finish(kex); |
| 250 | } |
| 251 | |
| 252 | Kex * |
| 253 | kex_setup(char *proposal[PROPOSAL_MAX]) |
| 254 | { |
| 255 | Kex *kex; |
| 256 | |
| 257 | kex = xcalloc(1, sizeof(*kex)); |
| 258 | buffer_init(&kex->peer); |
| 259 | buffer_init(&kex->my); |
| 260 | kex_prop2buf(&kex->my, proposal); |
| 261 | kex->done = 0; |
| 262 | |
| 263 | kex_send_kexinit(kex); /* we start */ |
| 264 | kex_reset_dispatch(); |
| 265 | |
| 266 | return kex; |
| 267 | } |
| 268 | |
| 269 | static void |
| 270 | kex_kexinit_finish(Kex *kex) |
| 271 | { |
| 272 | if (!(kex->flags & KEX_INIT_SENT)) |
| 273 | kex_send_kexinit(kex); |
| 274 | |
| 275 | kex_choose_conf(kex); |
| 276 | |
| 277 | if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX && |
| 278 | kex->kex[kex->kex_type] != NULL) { |
| 279 | (kex->kex[kex->kex_type])(kex); |
| 280 | } else { |
| 281 | fatal("Unsupported key exchange %d", kex->kex_type); |
| 282 | } |
| 283 | } |
| 284 | |
| 285 | static void |
| 286 | choose_enc(Enc *enc, char *client, char *server) |
| 287 | { |
| 288 | char *name = match_list(client, server, NULL); |
| 289 | if (name == NULL) |
| 290 | fatal("no matching cipher found: client %s server %s", |
| 291 | client, server); |
| 292 | if ((enc->cipher = cipher_by_name(name)) == NULL) |
| 293 | fatal("matching cipher is not supported: %s", name); |
| 294 | enc->name = name; |
| 295 | enc->enabled = 0; |
| 296 | enc->iv = NULL; |
| 297 | enc->key = NULL; |
| 298 | enc->key_len = cipher_keylen(enc->cipher); |
| 299 | enc->block_size = cipher_blocksize(enc->cipher); |
| 300 | } |
| 301 | |
| 302 | static void |
| 303 | choose_mac(Mac *mac, char *client, char *server) |
| 304 | { |
| 305 | char *name = match_list(client, server, NULL); |
| 306 | if (name == NULL) |
| 307 | fatal("no matching mac found: client %s server %s", |
| 308 | client, server); |
| 309 | if (mac_setup(mac, name) < 0) |
| 310 | fatal("unsupported mac %s", name); |
| 311 | /* truncate the key */ |
| 312 | if (datafellows & SSH_BUG_HMAC) |
| 313 | mac->key_len = 16; |
| 314 | mac->name = name; |
| 315 | mac->key = NULL; |
| 316 | mac->enabled = 0; |
| 317 | } |
| 318 | |
| 319 | static void |
| 320 | choose_comp(Comp *comp, char *client, char *server) |
| 321 | { |
| 322 | char *name = match_list(client, server, NULL); |
| 323 | if (name == NULL) |
| 324 | fatal("no matching comp found: client %s server %s", client, server); |
| 325 | if (strcmp(name, "zlib@openssh.com") == 0) { |
| 326 | comp->type = COMP_DELAYED; |
| 327 | } else if (strcmp(name, "zlib") == 0) { |
| 328 | comp->type = COMP_ZLIB; |
| 329 | } else if (strcmp(name, "none") == 0) { |
| 330 | comp->type = COMP_NONE; |
| 331 | } else { |
| 332 | fatal("unsupported comp %s", name); |
| 333 | } |
| 334 | comp->name = name; |
| 335 | } |
| 336 | |
| 337 | static void |
| 338 | choose_kex(Kex *k, char *client, char *server) |
| 339 | { |
| 340 | k->name = match_list(client, server, NULL); |
| 341 | if (k->name == NULL) |
| 342 | fatal("Unable to negotiate a key exchange method"); |
| 343 | if (strcmp(k->name, KEX_DH1) == 0) { |
| 344 | k->kex_type = KEX_DH_GRP1_SHA1; |
| 345 | k->evp_md = EVP_sha1(); |
| 346 | } else if (strcmp(k->name, KEX_DH14) == 0) { |
| 347 | k->kex_type = KEX_DH_GRP14_SHA1; |
| 348 | k->evp_md = EVP_sha1(); |
| 349 | } else if (strcmp(k->name, KEX_DHGEX_SHA1) == 0) { |
| 350 | k->kex_type = KEX_DH_GEX_SHA1; |
| 351 | k->evp_md = EVP_sha1(); |
| 352 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L |
| 353 | } else if (strcmp(k->name, KEX_DHGEX_SHA256) == 0) { |
| 354 | k->kex_type = KEX_DH_GEX_SHA256; |
| 355 | k->evp_md = evp_ssh_sha256(); |
| 356 | } else if (strncmp(k->name, KEX_ECDH_SHA2_STEM, |
| 357 | sizeof(KEX_ECDH_SHA2_STEM) - 1) == 0) { |
| 358 | k->kex_type = KEX_ECDH_SHA2; |
| 359 | k->evp_md = kex_ecdh_name_to_evpmd(k->name); |
| 360 | #endif |
| 361 | } else |
| 362 | fatal("bad kex alg %s", k->name); |
| 363 | } |
| 364 | |
| 365 | static void |
| 366 | choose_hostkeyalg(Kex *k, char *client, char *server) |
| 367 | { |
| 368 | char *hostkeyalg = match_list(client, server, NULL); |
| 369 | if (hostkeyalg == NULL) |
| 370 | fatal("no hostkey alg"); |
| 371 | k->hostkey_type = key_type_from_name(hostkeyalg); |
| 372 | if (k->hostkey_type == KEY_UNSPEC) |
| 373 | fatal("bad hostkey alg '%s'", hostkeyalg); |
| 374 | xfree(hostkeyalg); |
| 375 | } |
| 376 | |
| 377 | static int |
| 378 | proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) |
| 379 | { |
| 380 | static int check[] = { |
| 381 | PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 |
| 382 | }; |
| 383 | int *idx; |
| 384 | char *p; |
| 385 | |
| 386 | for (idx = &check[0]; *idx != -1; idx++) { |
| 387 | if ((p = strchr(my[*idx], ',')) != NULL) |
| 388 | *p = '\0'; |
| 389 | if ((p = strchr(peer[*idx], ',')) != NULL) |
| 390 | *p = '\0'; |
| 391 | if (strcmp(my[*idx], peer[*idx]) != 0) { |
| 392 | debug2("proposal mismatch: my %s peer %s", |
| 393 | my[*idx], peer[*idx]); |
| 394 | return (0); |
| 395 | } |
| 396 | } |
| 397 | debug2("proposals match"); |
| 398 | return (1); |
| 399 | } |
| 400 | |
| 401 | static void |
| 402 | kex_choose_conf(Kex *kex) |
| 403 | { |
| 404 | Newkeys *newkeys; |
| 405 | char **my, **peer; |
| 406 | char **cprop, **sprop; |
| 407 | int nenc, nmac, ncomp; |
| 408 | u_int mode, ctos, need; |
| 409 | int first_kex_follows, type; |
| 410 | |
| 411 | my = kex_buf2prop(&kex->my, NULL); |
| 412 | peer = kex_buf2prop(&kex->peer, &first_kex_follows); |
| 413 | |
| 414 | if (kex->server) { |
| 415 | cprop=peer; |
| 416 | sprop=my; |
| 417 | } else { |
| 418 | cprop=my; |
| 419 | sprop=peer; |
| 420 | } |
| 421 | |
| 422 | /* Check whether server offers roaming */ |
| 423 | if (!kex->server) { |
| 424 | char *roaming; |
| 425 | roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL); |
| 426 | if (roaming) { |
| 427 | kex->roaming = 1; |
| 428 | xfree(roaming); |
| 429 | } |
| 430 | } |
| 431 | |
| 432 | /* Algorithm Negotiation */ |
| 433 | for (mode = 0; mode < MODE_MAX; mode++) { |
| 434 | newkeys = xcalloc(1, sizeof(*newkeys)); |
| 435 | kex->newkeys[mode] = newkeys; |
| 436 | ctos = (!kex->server && mode == MODE_OUT) || |
| 437 | (kex->server && mode == MODE_IN); |
| 438 | nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; |
| 439 | nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; |
| 440 | ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; |
| 441 | choose_enc (&newkeys->enc, cprop[nenc], sprop[nenc]); |
| 442 | choose_mac (&newkeys->mac, cprop[nmac], sprop[nmac]); |
| 443 | choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); |
| 444 | debug("kex: %s %s %s %s", |
| 445 | ctos ? "client->server" : "server->client", |
| 446 | newkeys->enc.name, |
| 447 | newkeys->mac.name, |
| 448 | newkeys->comp.name); |
| 449 | } |
| 450 | choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); |
| 451 | choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], |
| 452 | sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); |
| 453 | need = 0; |
| 454 | for (mode = 0; mode < MODE_MAX; mode++) { |
| 455 | newkeys = kex->newkeys[mode]; |
| 456 | if (need < newkeys->enc.key_len) |
| 457 | need = newkeys->enc.key_len; |
| 458 | if (need < newkeys->enc.block_size) |
| 459 | need = newkeys->enc.block_size; |
| 460 | if (need < newkeys->mac.key_len) |
| 461 | need = newkeys->mac.key_len; |
| 462 | } |
| 463 | /* XXX need runden? */ |
| 464 | kex->we_need = need; |
| 465 | |
| 466 | /* ignore the next message if the proposals do not match */ |
| 467 | if (first_kex_follows && !proposals_match(my, peer) && |
| 468 | !(datafellows & SSH_BUG_FIRSTKEX)) { |
| 469 | type = packet_read(); |
| 470 | debug2("skipping next packet (type %u)", type); |
| 471 | } |
| 472 | |
| 473 | kex_prop_free(my); |
| 474 | kex_prop_free(peer); |
| 475 | } |
| 476 | |
| 477 | static u_char * |
| 478 | derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, |
| 479 | BIGNUM *shared_secret) |
| 480 | { |
| 481 | Buffer b; |
| 482 | EVP_MD_CTX md; |
| 483 | char c = id; |
| 484 | u_int have; |
| 485 | int mdsz; |
| 486 | u_char *digest; |
| 487 | |
| 488 | if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0) |
| 489 | fatal("bad kex md size %d", mdsz); |
| 490 | digest = xmalloc(roundup(need, mdsz)); |
| 491 | |
| 492 | buffer_init(&b); |
| 493 | buffer_put_bignum2(&b, shared_secret); |
| 494 | |
| 495 | /* K1 = HASH(K || H || "A" || session_id) */ |
| 496 | EVP_DigestInit(&md, kex->evp_md); |
| 497 | if (!(datafellows & SSH_BUG_DERIVEKEY)) |
| 498 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); |
| 499 | EVP_DigestUpdate(&md, hash, hashlen); |
| 500 | EVP_DigestUpdate(&md, &c, 1); |
| 501 | EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len); |
| 502 | EVP_DigestFinal(&md, digest, NULL); |
| 503 | |
| 504 | /* |
| 505 | * expand key: |
| 506 | * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) |
| 507 | * Key = K1 || K2 || ... || Kn |
| 508 | */ |
| 509 | for (have = mdsz; need > have; have += mdsz) { |
| 510 | EVP_DigestInit(&md, kex->evp_md); |
| 511 | if (!(datafellows & SSH_BUG_DERIVEKEY)) |
| 512 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); |
| 513 | EVP_DigestUpdate(&md, hash, hashlen); |
| 514 | EVP_DigestUpdate(&md, digest, have); |
| 515 | EVP_DigestFinal(&md, digest + have, NULL); |
| 516 | } |
| 517 | buffer_free(&b); |
| 518 | #ifdef DEBUG_KEX |
| 519 | fprintf(stderr, "key '%c'== ", c); |
| 520 | dump_digest("key", digest, need); |
| 521 | #endif |
| 522 | return digest; |
| 523 | } |
| 524 | |
| 525 | Newkeys *current_keys[MODE_MAX]; |
| 526 | |
| 527 | #define NKEYS 6 |
| 528 | void |
| 529 | kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret) |
| 530 | { |
| 531 | u_char *keys[NKEYS]; |
| 532 | u_int i, mode, ctos; |
| 533 | |
| 534 | for (i = 0; i < NKEYS; i++) { |
| 535 | keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, |
| 536 | shared_secret); |
| 537 | } |
| 538 | |
| 539 | debug2("kex_derive_keys"); |
| 540 | for (mode = 0; mode < MODE_MAX; mode++) { |
| 541 | current_keys[mode] = kex->newkeys[mode]; |
| 542 | kex->newkeys[mode] = NULL; |
| 543 | ctos = (!kex->server && mode == MODE_OUT) || |
| 544 | (kex->server && mode == MODE_IN); |
| 545 | current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; |
| 546 | current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; |
| 547 | current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; |
| 548 | } |
| 549 | } |
| 550 | |
| 551 | Newkeys * |
| 552 | kex_get_newkeys(int mode) |
| 553 | { |
| 554 | Newkeys *ret; |
| 555 | |
| 556 | ret = current_keys[mode]; |
| 557 | current_keys[mode] = NULL; |
| 558 | return ret; |
| 559 | } |
| 560 | |
| 561 | void |
| 562 | derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, |
| 563 | u_int8_t cookie[8], u_int8_t id[16]) |
| 564 | { |
| 565 | const EVP_MD *evp_md = EVP_md5(); |
| 566 | EVP_MD_CTX md; |
| 567 | u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE]; |
| 568 | int len; |
| 569 | |
| 570 | EVP_DigestInit(&md, evp_md); |
| 571 | |
| 572 | len = BN_num_bytes(host_modulus); |
| 573 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) |
| 574 | fatal("%s: bad host modulus (len %d)", __func__, len); |
| 575 | BN_bn2bin(host_modulus, nbuf); |
| 576 | EVP_DigestUpdate(&md, nbuf, len); |
| 577 | |
| 578 | len = BN_num_bytes(server_modulus); |
| 579 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) |
| 580 | fatal("%s: bad server modulus (len %d)", __func__, len); |
| 581 | BN_bn2bin(server_modulus, nbuf); |
| 582 | EVP_DigestUpdate(&md, nbuf, len); |
| 583 | |
| 584 | EVP_DigestUpdate(&md, cookie, 8); |
| 585 | |
| 586 | EVP_DigestFinal(&md, obuf, NULL); |
| 587 | memcpy(id, obuf, 16); |
| 588 | |
| 589 | memset(nbuf, 0, sizeof(nbuf)); |
| 590 | memset(obuf, 0, sizeof(obuf)); |
| 591 | memset(&md, 0, sizeof(md)); |
| 592 | } |
| 593 | |
| 594 | #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH) |
| 595 | void |
| 596 | dump_digest(char *msg, u_char *digest, int len) |
| 597 | { |
| 598 | int i; |
| 599 | |
| 600 | fprintf(stderr, "%s\n", msg); |
| 601 | for (i = 0; i < len; i++) { |
| 602 | fprintf(stderr, "%02x", digest[i]); |
| 603 | if (i%32 == 31) |
| 604 | fprintf(stderr, "\n"); |
| 605 | else if (i%8 == 7) |
| 606 | fprintf(stderr, " "); |
| 607 | } |
| 608 | fprintf(stderr, "\n"); |
| 609 | } |
| 610 | #endif |