Annotation of src/usr.bin/ssh/kex.c, Revision 1.89
1.89 ! djm 1: /* $OpenBSD: kex.c,v 1.88 2013/01/08 18:49:04 markus Exp $ */
1.1 markus 2: /*
1.36 markus 3: * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
1.1 markus 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:
1.73 stevesk 26: #include <sys/param.h>
1.18 markus 27:
1.76 deraadt 28: #include <signal.h>
1.75 stevesk 29: #include <stdio.h>
1.74 stevesk 30: #include <stdlib.h>
1.72 stevesk 31: #include <string.h>
1.1 markus 32:
1.76 deraadt 33: #include <openssl/crypto.h>
34:
35: #include "xmalloc.h"
1.1 markus 36: #include "ssh2.h"
37: #include "buffer.h"
1.7 markus 38: #include "packet.h"
1.1 markus 39: #include "compat.h"
1.18 markus 40: #include "cipher.h"
1.76 deraadt 41: #include "key.h"
1.1 markus 42: #include "kex.h"
1.18 markus 43: #include "log.h"
1.21 markus 44: #include "mac.h"
1.23 markus 45: #include "match.h"
1.26 markus 46: #include "dispatch.h"
1.48 provos 47: #include "monitor.h"
1.82 andreas 48: #include "roaming.h"
1.48 provos 49:
1.35 itojun 50: /* prototype */
51: static void kex_kexinit_finish(Kex *);
52: static void kex_choose_conf(Kex *);
1.86 djm 53:
1.89 ! djm 54: struct kexalg {
! 55: char *name;
! 56: int type;
! 57: int ec_nid;
! 58: const EVP_MD *(*mdfunc)(void);
! 59: };
! 60: static const struct kexalg kexalgs[] = {
! 61: { KEX_DH1, KEX_DH_GRP1_SHA1, 0, EVP_sha1 },
! 62: { KEX_DH14, KEX_DH_GRP14_SHA1, 0, EVP_sha1 },
! 63: { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, EVP_sha1 },
! 64: { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, EVP_sha256 },
! 65: { KEX_DH1, KEX_DH_GRP1_SHA1, 0, EVP_sha1 },
! 66: { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2, NID_X9_62_prime256v1, EVP_sha256 },
! 67: { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1, EVP_sha384 },
! 68: { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1, EVP_sha512 },
! 69: { NULL, -1, -1, NULL},
! 70: };
! 71:
! 72: char *
! 73: kex_alg_list(void)
! 74: {
! 75: char *ret = NULL;
! 76: size_t nlen, rlen = 0;
! 77: const struct kexalg *k;
! 78:
! 79: for (k = kexalgs; k->name != NULL; k++) {
! 80: if (ret != NULL)
! 81: ret[rlen++] = '\n';
! 82: nlen = strlen(k->name);
! 83: ret = xrealloc(ret, 1, rlen + nlen + 2);
! 84: memcpy(ret + rlen, k->name, nlen + 1);
! 85: rlen += nlen;
! 86: }
! 87: return ret;
! 88: }
! 89:
! 90: static const struct kexalg *
! 91: kex_alg_by_name(const char *name)
! 92: {
! 93: const struct kexalg *k;
! 94:
! 95: for (k = kexalgs; k->name != NULL; k++) {
! 96: if (strcmp(k->name, name) == 0)
! 97: return k;
! 98: }
! 99: return NULL;
! 100: }
! 101:
1.86 djm 102: /* Validate KEX method name list */
103: int
104: kex_names_valid(const char *names)
105: {
106: char *s, *cp, *p;
107:
108: if (names == NULL || strcmp(names, "") == 0)
109: return 0;
110: s = cp = xstrdup(names);
111: for ((p = strsep(&cp, ",")); p && *p != '\0';
112: (p = strsep(&cp, ","))) {
1.89 ! djm 113: if (kex_alg_by_name(p) == NULL) {
1.86 djm 114: error("Unsupported KEX algorithm \"%.100s\"", p);
115: xfree(s);
116: return 0;
117: }
118: }
119: debug3("kex names ok: [%s]", names);
120: xfree(s);
121: return 1;
122: }
1.26 markus 123:
124: /* put algorithm proposal into buffer */
1.35 itojun 125: static void
1.26 markus 126: kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
1.1 markus 127: {
1.61 djm 128: u_int i;
1.26 markus 129:
130: buffer_clear(b);
1.49 markus 131: /*
132: * add a dummy cookie, the cookie will be overwritten by
133: * kex_send_kexinit(), each time a kexinit is set
134: */
135: for (i = 0; i < KEX_COOKIE_LEN; i++)
136: buffer_put_char(b, 0);
1.1 markus 137: for (i = 0; i < PROPOSAL_MAX; i++)
1.26 markus 138: buffer_put_cstring(b, proposal[i]);
139: buffer_put_char(b, 0); /* first_kex_packet_follows */
140: buffer_put_int(b, 0); /* uint32 reserved */
1.1 markus 141: }
142:
1.26 markus 143: /* parse buffer and return algorithm proposal */
1.35 itojun 144: static char **
1.53 markus 145: kex_buf2prop(Buffer *raw, int *first_kex_follows)
1.7 markus 146: {
1.26 markus 147: Buffer b;
1.78 djm 148: u_int i;
1.26 markus 149: char **proposal;
1.7 markus 150:
1.70 djm 151: proposal = xcalloc(PROPOSAL_MAX, sizeof(char *));
1.7 markus 152:
1.26 markus 153: buffer_init(&b);
154: buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
1.7 markus 155: /* skip cookie */
156: for (i = 0; i < KEX_COOKIE_LEN; i++)
1.26 markus 157: buffer_get_char(&b);
1.7 markus 158: /* extract kex init proposal strings */
159: for (i = 0; i < PROPOSAL_MAX; i++) {
1.83 djm 160: proposal[i] = buffer_get_cstring(&b,NULL);
1.26 markus 161: debug2("kex_parse_kexinit: %s", proposal[i]);
1.7 markus 162: }
1.26 markus 163: /* first kex follows / reserved */
164: i = buffer_get_char(&b);
1.53 markus 165: if (first_kex_follows != NULL)
166: *first_kex_follows = i;
1.26 markus 167: debug2("kex_parse_kexinit: first_kex_follows %d ", i);
168: i = buffer_get_int(&b);
1.78 djm 169: debug2("kex_parse_kexinit: reserved %u ", i);
1.26 markus 170: buffer_free(&b);
171: return proposal;
1.1 markus 172: }
173:
1.35 itojun 174: static void
1.26 markus 175: kex_prop_free(char **proposal)
1.1 markus 176: {
1.61 djm 177: u_int i;
1.26 markus 178:
179: for (i = 0; i < PROPOSAL_MAX; i++)
180: xfree(proposal[i]);
181: xfree(proposal);
1.1 markus 182: }
183:
1.78 djm 184: /* ARGSUSED */
1.35 itojun 185: static void
1.41 markus 186: kex_protocol_error(int type, u_int32_t seq, void *ctxt)
1.1 markus 187: {
1.41 markus 188: error("Hm, kex protocol error: type %d seq %u", type, seq);
1.26 markus 189: }
1.1 markus 190:
1.35 itojun 191: static void
1.44 markus 192: kex_reset_dispatch(void)
1.29 markus 193: {
1.42 markus 194: dispatch_range(SSH2_MSG_TRANSPORT_MIN,
195: SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
1.44 markus 196: dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
1.29 markus 197: }
198:
199: void
1.28 markus 200: kex_finish(Kex *kex)
1.26 markus 201: {
1.44 markus 202: kex_reset_dispatch();
1.28 markus 203:
1.26 markus 204: packet_start(SSH2_MSG_NEWKEYS);
205: packet_send();
206: /* packet_write_wait(); */
207: debug("SSH2_MSG_NEWKEYS sent");
1.19 stevesk 208:
1.52 markus 209: debug("expecting SSH2_MSG_NEWKEYS");
1.40 markus 210: packet_read_expect(SSH2_MSG_NEWKEYS);
1.46 markus 211: packet_check_eom();
1.26 markus 212: debug("SSH2_MSG_NEWKEYS received");
1.32 markus 213:
1.30 markus 214: kex->done = 1;
1.26 markus 215: buffer_clear(&kex->peer);
1.27 markus 216: /* buffer_clear(&kex->my); */
1.26 markus 217: kex->flags &= ~KEX_INIT_SENT;
1.32 markus 218: xfree(kex->name);
219: kex->name = NULL;
1.26 markus 220: }
1.1 markus 221:
1.26 markus 222: void
223: kex_send_kexinit(Kex *kex)
224: {
1.60 avsm 225: u_int32_t rnd = 0;
1.49 markus 226: u_char *cookie;
1.61 djm 227: u_int i;
1.49 markus 228:
1.29 markus 229: if (kex == NULL) {
230: error("kex_send_kexinit: no kex, cannot rekey");
231: return;
232: }
1.28 markus 233: if (kex->flags & KEX_INIT_SENT) {
234: debug("KEX_INIT_SENT");
235: return;
236: }
1.30 markus 237: kex->done = 0;
1.49 markus 238:
239: /* generate a random cookie */
240: if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
241: fatal("kex_send_kexinit: kex proposal too short");
242: cookie = buffer_ptr(&kex->my);
243: for (i = 0; i < KEX_COOKIE_LEN; i++) {
244: if (i % 4 == 0)
1.60 avsm 245: rnd = arc4random();
246: cookie[i] = rnd;
247: rnd >>= 8;
1.49 markus 248: }
1.26 markus 249: packet_start(SSH2_MSG_KEXINIT);
250: packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
251: packet_send();
252: debug("SSH2_MSG_KEXINIT sent");
253: kex->flags |= KEX_INIT_SENT;
1.1 markus 254: }
255:
1.78 djm 256: /* ARGSUSED */
1.26 markus 257: void
1.41 markus 258: kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
1.11 provos 259: {
1.26 markus 260: char *ptr;
1.61 djm 261: u_int i, dlen;
1.26 markus 262: Kex *kex = (Kex *)ctxt;
1.11 provos 263:
1.26 markus 264: debug("SSH2_MSG_KEXINIT received");
1.29 markus 265: if (kex == NULL)
266: fatal("kex_input_kexinit: no kex, cannot rekey");
1.11 provos 267:
1.26 markus 268: ptr = packet_get_raw(&dlen);
269: buffer_append(&kex->peer, ptr, dlen);
1.31 markus 270:
271: /* discard packet */
272: for (i = 0; i < KEX_COOKIE_LEN; i++)
273: packet_get_char();
274: for (i = 0; i < PROPOSAL_MAX; i++)
275: xfree(packet_get_string(NULL));
1.87 djm 276: /*
277: * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
278: * KEX method has the server move first, but a server might be using
279: * a custom method or one that we otherwise don't support. We should
280: * be prepared to remember first_kex_follows here so we can eat a
281: * packet later.
282: * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
283: * for cases where the server *doesn't* go first. I guess we should
284: * ignore it when it is set for these cases, which is what we do now.
285: */
286: (void) packet_get_char(); /* first_kex_follows */
287: (void) packet_get_int(); /* reserved */
1.39 markus 288: packet_check_eom();
1.19 stevesk 289:
1.26 markus 290: kex_kexinit_finish(kex);
291: }
1.11 provos 292:
1.26 markus 293: Kex *
1.28 markus 294: kex_setup(char *proposal[PROPOSAL_MAX])
1.26 markus 295: {
296: Kex *kex;
1.11 provos 297:
1.70 djm 298: kex = xcalloc(1, sizeof(*kex));
1.26 markus 299: buffer_init(&kex->peer);
300: buffer_init(&kex->my);
301: kex_prop2buf(&kex->my, proposal);
1.30 markus 302: kex->done = 0;
1.26 markus 303:
304: kex_send_kexinit(kex); /* we start */
1.44 markus 305: kex_reset_dispatch();
1.26 markus 306:
307: return kex;
1.11 provos 308: }
309:
1.35 itojun 310: static void
1.26 markus 311: kex_kexinit_finish(Kex *kex)
1.1 markus 312: {
1.26 markus 313: if (!(kex->flags & KEX_INIT_SENT))
314: kex_send_kexinit(kex);
1.1 markus 315:
1.26 markus 316: kex_choose_conf(kex);
1.1 markus 317:
1.54 markus 318: if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
319: kex->kex[kex->kex_type] != NULL) {
320: (kex->kex[kex->kex_type])(kex);
321: } else {
1.26 markus 322: fatal("Unsupported key exchange %d", kex->kex_type);
1.1 markus 323: }
324: }
325:
1.35 itojun 326: static void
1.1 markus 327: choose_enc(Enc *enc, char *client, char *server)
328: {
1.23 markus 329: char *name = match_list(client, server, NULL);
1.1 markus 330: if (name == NULL)
1.78 djm 331: fatal("no matching cipher found: client %s server %s",
332: client, server);
1.45 markus 333: if ((enc->cipher = cipher_by_name(name)) == NULL)
1.12 markus 334: fatal("matching cipher is not supported: %s", name);
1.1 markus 335: enc->name = name;
336: enc->enabled = 0;
337: enc->iv = NULL;
1.88 markus 338: enc->iv_len = cipher_ivlen(enc->cipher);
1.1 markus 339: enc->key = NULL;
1.45 markus 340: enc->key_len = cipher_keylen(enc->cipher);
341: enc->block_size = cipher_blocksize(enc->cipher);
1.1 markus 342: }
1.69 deraadt 343:
1.35 itojun 344: static void
1.1 markus 345: choose_mac(Mac *mac, char *client, char *server)
346: {
1.23 markus 347: char *name = match_list(client, server, NULL);
1.1 markus 348: if (name == NULL)
1.78 djm 349: fatal("no matching mac found: client %s server %s",
350: client, server);
1.79 djm 351: if (mac_setup(mac, name) < 0)
1.1 markus 352: fatal("unsupported mac %s", name);
1.21 markus 353: /* truncate the key */
354: if (datafellows & SSH_BUG_HMAC)
355: mac->key_len = 16;
1.1 markus 356: mac->name = name;
357: mac->key = NULL;
358: mac->enabled = 0;
359: }
1.69 deraadt 360:
1.35 itojun 361: static void
1.1 markus 362: choose_comp(Comp *comp, char *client, char *server)
363: {
1.23 markus 364: char *name = match_list(client, server, NULL);
1.1 markus 365: if (name == NULL)
366: fatal("no matching comp found: client %s server %s", client, server);
1.64 markus 367: if (strcmp(name, "zlib@openssh.com") == 0) {
368: comp->type = COMP_DELAYED;
369: } else if (strcmp(name, "zlib") == 0) {
370: comp->type = COMP_ZLIB;
1.1 markus 371: } else if (strcmp(name, "none") == 0) {
1.64 markus 372: comp->type = COMP_NONE;
1.1 markus 373: } else {
374: fatal("unsupported comp %s", name);
375: }
376: comp->name = name;
377: }
1.69 deraadt 378:
1.35 itojun 379: static void
1.1 markus 380: choose_kex(Kex *k, char *client, char *server)
381: {
1.89 ! djm 382: const struct kexalg *kexalg;
! 383:
1.23 markus 384: k->name = match_list(client, server, NULL);
1.1 markus 385: if (k->name == NULL)
1.78 djm 386: fatal("Unable to negotiate a key exchange method");
1.89 ! djm 387: if ((kexalg = kex_alg_by_name(k->name)) == NULL)
! 388: fatal("unsupported kex alg %s", k->name);
! 389: k->kex_type = kexalg->type;
! 390: k->evp_md = kexalg->mdfunc();
! 391: k->ec_nid = kexalg->ec_nid;
1.1 markus 392: }
1.65 djm 393:
1.35 itojun 394: static void
1.1 markus 395: choose_hostkeyalg(Kex *k, char *client, char *server)
396: {
1.23 markus 397: char *hostkeyalg = match_list(client, server, NULL);
1.13 markus 398: if (hostkeyalg == NULL)
1.1 markus 399: fatal("no hostkey alg");
1.13 markus 400: k->hostkey_type = key_type_from_name(hostkeyalg);
401: if (k->hostkey_type == KEY_UNSPEC)
402: fatal("bad hostkey alg '%s'", hostkeyalg);
1.17 markus 403: xfree(hostkeyalg);
1.1 markus 404: }
405:
1.56 djm 406: static int
1.53 markus 407: proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
408: {
409: static int check[] = {
410: PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
411: };
412: int *idx;
413: char *p;
414:
415: for (idx = &check[0]; *idx != -1; idx++) {
416: if ((p = strchr(my[*idx], ',')) != NULL)
417: *p = '\0';
418: if ((p = strchr(peer[*idx], ',')) != NULL)
419: *p = '\0';
420: if (strcmp(my[*idx], peer[*idx]) != 0) {
421: debug2("proposal mismatch: my %s peer %s",
422: my[*idx], peer[*idx]);
423: return (0);
424: }
425: }
426: debug2("proposals match");
427: return (1);
428: }
429:
1.35 itojun 430: static void
1.27 markus 431: kex_choose_conf(Kex *kex)
1.1 markus 432: {
1.27 markus 433: Newkeys *newkeys;
1.26 markus 434: char **my, **peer;
435: char **cprop, **sprop;
1.27 markus 436: int nenc, nmac, ncomp;
1.88 markus 437: u_int mode, ctos, need, authlen;
1.53 markus 438: int first_kex_follows, type;
1.1 markus 439:
1.53 markus 440: my = kex_buf2prop(&kex->my, NULL);
441: peer = kex_buf2prop(&kex->peer, &first_kex_follows);
1.26 markus 442:
1.27 markus 443: if (kex->server) {
1.26 markus 444: cprop=peer;
445: sprop=my;
446: } else {
447: cprop=my;
448: sprop=peer;
1.82 andreas 449: }
450:
451: /* Check whether server offers roaming */
452: if (!kex->server) {
453: char *roaming;
454: roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL);
455: if (roaming) {
456: kex->roaming = 1;
457: xfree(roaming);
458: }
1.26 markus 459: }
1.1 markus 460:
1.30 markus 461: /* Algorithm Negotiation */
1.1 markus 462: for (mode = 0; mode < MODE_MAX; mode++) {
1.70 djm 463: newkeys = xcalloc(1, sizeof(*newkeys));
1.30 markus 464: kex->newkeys[mode] = newkeys;
1.78 djm 465: ctos = (!kex->server && mode == MODE_OUT) ||
466: (kex->server && mode == MODE_IN);
1.1 markus 467: nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
468: nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
469: ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
1.88 markus 470: choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]);
471: /* ignore mac for authenticated encryption */
472: authlen = cipher_authlen(newkeys->enc.cipher);
473: if (authlen == 0)
474: choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]);
1.27 markus 475: choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
1.2 markus 476: debug("kex: %s %s %s %s",
1.1 markus 477: ctos ? "client->server" : "server->client",
1.27 markus 478: newkeys->enc.name,
1.88 markus 479: authlen == 0 ? newkeys->mac.name : "<implicit>",
1.27 markus 480: newkeys->comp.name);
1.1 markus 481: }
1.27 markus 482: choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
483: choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
1.1 markus 484: sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
485: need = 0;
486: for (mode = 0; mode < MODE_MAX; mode++) {
1.30 markus 487: newkeys = kex->newkeys[mode];
1.45 markus 488: if (need < newkeys->enc.key_len)
489: need = newkeys->enc.key_len;
490: if (need < newkeys->enc.block_size)
491: need = newkeys->enc.block_size;
1.88 markus 492: if (need < newkeys->enc.iv_len)
493: need = newkeys->enc.iv_len;
1.27 markus 494: if (need < newkeys->mac.key_len)
495: need = newkeys->mac.key_len;
1.1 markus 496: }
1.7 markus 497: /* XXX need runden? */
1.27 markus 498: kex->we_need = need;
1.53 markus 499:
500: /* ignore the next message if the proposals do not match */
1.56 djm 501: if (first_kex_follows && !proposals_match(my, peer) &&
1.63 djm 502: !(datafellows & SSH_BUG_FIRSTKEX)) {
1.53 markus 503: type = packet_read();
504: debug2("skipping next packet (type %u)", type);
505: }
1.26 markus 506:
507: kex_prop_free(my);
508: kex_prop_free(peer);
509: }
510:
1.35 itojun 511: static u_char *
1.65 djm 512: derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen,
513: BIGNUM *shared_secret)
1.26 markus 514: {
515: Buffer b;
516: EVP_MD_CTX md;
517: char c = id;
1.61 djm 518: u_int have;
1.65 djm 519: int mdsz;
1.61 djm 520: u_char *digest;
1.62 djm 521:
1.65 djm 522: if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0)
523: fatal("bad kex md size %d", mdsz);
1.68 deraadt 524: digest = xmalloc(roundup(need, mdsz));
1.26 markus 525:
526: buffer_init(&b);
527: buffer_put_bignum2(&b, shared_secret);
528:
1.30 markus 529: /* K1 = HASH(K || H || "A" || session_id) */
1.65 djm 530: EVP_DigestInit(&md, kex->evp_md);
1.34 markus 531: if (!(datafellows & SSH_BUG_DERIVEKEY))
532: EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
1.65 djm 533: EVP_DigestUpdate(&md, hash, hashlen);
1.30 markus 534: EVP_DigestUpdate(&md, &c, 1);
1.27 markus 535: EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
1.26 markus 536: EVP_DigestFinal(&md, digest, NULL);
537:
1.30 markus 538: /*
539: * expand key:
540: * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
541: * Key = K1 || K2 || ... || Kn
542: */
1.26 markus 543: for (have = mdsz; need > have; have += mdsz) {
1.65 djm 544: EVP_DigestInit(&md, kex->evp_md);
1.34 markus 545: if (!(datafellows & SSH_BUG_DERIVEKEY))
546: EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
1.65 djm 547: EVP_DigestUpdate(&md, hash, hashlen);
1.26 markus 548: EVP_DigestUpdate(&md, digest, have);
549: EVP_DigestFinal(&md, digest + have, NULL);
550: }
551: buffer_free(&b);
552: #ifdef DEBUG_KEX
553: fprintf(stderr, "key '%c'== ", c);
554: dump_digest("key", digest, need);
555: #endif
556: return digest;
1.1 markus 557: }
558:
1.30 markus 559: Newkeys *current_keys[MODE_MAX];
1.27 markus 560:
1.23 markus 561: #define NKEYS 6
1.26 markus 562: void
1.65 djm 563: kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret)
1.1 markus 564: {
1.15 markus 565: u_char *keys[NKEYS];
1.61 djm 566: u_int i, mode, ctos;
1.1 markus 567:
1.65 djm 568: for (i = 0; i < NKEYS; i++) {
569: keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen,
570: shared_secret);
571: }
1.1 markus 572:
1.52 markus 573: debug2("kex_derive_keys");
1.1 markus 574: for (mode = 0; mode < MODE_MAX; mode++) {
1.30 markus 575: current_keys[mode] = kex->newkeys[mode];
576: kex->newkeys[mode] = NULL;
1.69 deraadt 577: ctos = (!kex->server && mode == MODE_OUT) ||
578: (kex->server && mode == MODE_IN);
1.30 markus 579: current_keys[mode]->enc.iv = keys[ctos ? 0 : 1];
580: current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
581: current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
1.1 markus 582: }
1.27 markus 583: }
584:
585: Newkeys *
586: kex_get_newkeys(int mode)
587: {
1.30 markus 588: Newkeys *ret;
589:
590: ret = current_keys[mode];
591: current_keys[mode] = NULL;
592: return ret;
1.57 djm 593: }
594:
595: void
596: derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
597: u_int8_t cookie[8], u_int8_t id[16])
598: {
599: const EVP_MD *evp_md = EVP_md5();
600: EVP_MD_CTX md;
601: u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE];
602: int len;
603:
604: EVP_DigestInit(&md, evp_md);
605:
606: len = BN_num_bytes(host_modulus);
1.61 djm 607: if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
1.57 djm 608: fatal("%s: bad host modulus (len %d)", __func__, len);
609: BN_bn2bin(host_modulus, nbuf);
610: EVP_DigestUpdate(&md, nbuf, len);
611:
612: len = BN_num_bytes(server_modulus);
1.61 djm 613: if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
1.57 djm 614: fatal("%s: bad server modulus (len %d)", __func__, len);
615: BN_bn2bin(server_modulus, nbuf);
616: EVP_DigestUpdate(&md, nbuf, len);
617:
618: EVP_DigestUpdate(&md, cookie, 8);
619:
1.58 djm 620: EVP_DigestFinal(&md, obuf, NULL);
1.57 djm 621: memcpy(id, obuf, 16);
622:
623: memset(nbuf, 0, sizeof(nbuf));
624: memset(obuf, 0, sizeof(obuf));
625: memset(&md, 0, sizeof(md));
1.1 markus 626: }
1.26 markus 627:
1.84 djm 628: #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
1.26 markus 629: void
630: dump_digest(char *msg, u_char *digest, int len)
631: {
1.84 djm 632: int i;
1.26 markus 633:
634: fprintf(stderr, "%s\n", msg);
1.77 stevesk 635: for (i = 0; i < len; i++) {
1.26 markus 636: fprintf(stderr, "%02x", digest[i]);
637: if (i%32 == 31)
638: fprintf(stderr, "\n");
639: else if (i%8 == 7)
640: fprintf(stderr, " ");
641: }
642: fprintf(stderr, "\n");
643: }
644: #endif
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