Annotation of src/usr.bin/ssh/kex.c, Revision 1.91
1.91 ! djm 1: /* $OpenBSD: kex.c,v 1.90 2013/04/19 12:07:08 djm 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_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2, NID_X9_62_prime256v1, EVP_sha256 },
66: { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1, EVP_sha384 },
67: { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1, EVP_sha512 },
68: { NULL, -1, -1, NULL},
69: };
70:
71: char *
72: kex_alg_list(void)
73: {
74: char *ret = NULL;
75: size_t nlen, rlen = 0;
76: const struct kexalg *k;
77:
78: for (k = kexalgs; k->name != NULL; k++) {
79: if (ret != NULL)
80: ret[rlen++] = '\n';
81: nlen = strlen(k->name);
82: ret = xrealloc(ret, 1, rlen + nlen + 2);
83: memcpy(ret + rlen, k->name, nlen + 1);
84: rlen += nlen;
85: }
86: return ret;
87: }
88:
89: static const struct kexalg *
90: kex_alg_by_name(const char *name)
91: {
92: const struct kexalg *k;
93:
94: for (k = kexalgs; k->name != NULL; k++) {
95: if (strcmp(k->name, name) == 0)
96: return k;
97: }
98: return NULL;
99: }
100:
1.86 djm 101: /* Validate KEX method name list */
102: int
103: kex_names_valid(const char *names)
104: {
105: char *s, *cp, *p;
106:
107: if (names == NULL || strcmp(names, "") == 0)
108: return 0;
109: s = cp = xstrdup(names);
110: for ((p = strsep(&cp, ",")); p && *p != '\0';
111: (p = strsep(&cp, ","))) {
1.89 djm 112: if (kex_alg_by_name(p) == NULL) {
1.86 djm 113: error("Unsupported KEX algorithm \"%.100s\"", p);
1.91 ! djm 114: free(s);
1.86 djm 115: return 0;
116: }
117: }
118: debug3("kex names ok: [%s]", names);
1.91 ! djm 119: free(s);
1.86 djm 120: return 1;
121: }
1.26 markus 122:
123: /* put algorithm proposal into buffer */
1.35 itojun 124: static void
1.26 markus 125: kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
1.1 markus 126: {
1.61 djm 127: u_int i;
1.26 markus 128:
129: buffer_clear(b);
1.49 markus 130: /*
131: * add a dummy cookie, the cookie will be overwritten by
132: * kex_send_kexinit(), each time a kexinit is set
133: */
134: for (i = 0; i < KEX_COOKIE_LEN; i++)
135: buffer_put_char(b, 0);
1.1 markus 136: for (i = 0; i < PROPOSAL_MAX; i++)
1.26 markus 137: buffer_put_cstring(b, proposal[i]);
138: buffer_put_char(b, 0); /* first_kex_packet_follows */
139: buffer_put_int(b, 0); /* uint32 reserved */
1.1 markus 140: }
141:
1.26 markus 142: /* parse buffer and return algorithm proposal */
1.35 itojun 143: static char **
1.53 markus 144: kex_buf2prop(Buffer *raw, int *first_kex_follows)
1.7 markus 145: {
1.26 markus 146: Buffer b;
1.78 djm 147: u_int i;
1.26 markus 148: char **proposal;
1.7 markus 149:
1.70 djm 150: proposal = xcalloc(PROPOSAL_MAX, sizeof(char *));
1.7 markus 151:
1.26 markus 152: buffer_init(&b);
153: buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
1.7 markus 154: /* skip cookie */
155: for (i = 0; i < KEX_COOKIE_LEN; i++)
1.26 markus 156: buffer_get_char(&b);
1.7 markus 157: /* extract kex init proposal strings */
158: for (i = 0; i < PROPOSAL_MAX; i++) {
1.83 djm 159: proposal[i] = buffer_get_cstring(&b,NULL);
1.26 markus 160: debug2("kex_parse_kexinit: %s", proposal[i]);
1.7 markus 161: }
1.26 markus 162: /* first kex follows / reserved */
163: i = buffer_get_char(&b);
1.53 markus 164: if (first_kex_follows != NULL)
165: *first_kex_follows = i;
1.26 markus 166: debug2("kex_parse_kexinit: first_kex_follows %d ", i);
167: i = buffer_get_int(&b);
1.78 djm 168: debug2("kex_parse_kexinit: reserved %u ", i);
1.26 markus 169: buffer_free(&b);
170: return proposal;
1.1 markus 171: }
172:
1.35 itojun 173: static void
1.26 markus 174: kex_prop_free(char **proposal)
1.1 markus 175: {
1.61 djm 176: u_int i;
1.26 markus 177:
178: for (i = 0; i < PROPOSAL_MAX; i++)
1.91 ! djm 179: free(proposal[i]);
! 180: free(proposal);
1.1 markus 181: }
182:
1.78 djm 183: /* ARGSUSED */
1.35 itojun 184: static void
1.41 markus 185: kex_protocol_error(int type, u_int32_t seq, void *ctxt)
1.1 markus 186: {
1.41 markus 187: error("Hm, kex protocol error: type %d seq %u", type, seq);
1.26 markus 188: }
1.1 markus 189:
1.35 itojun 190: static void
1.44 markus 191: kex_reset_dispatch(void)
1.29 markus 192: {
1.42 markus 193: dispatch_range(SSH2_MSG_TRANSPORT_MIN,
194: SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
1.44 markus 195: dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
1.29 markus 196: }
197:
198: void
1.28 markus 199: kex_finish(Kex *kex)
1.26 markus 200: {
1.44 markus 201: kex_reset_dispatch();
1.28 markus 202:
1.26 markus 203: packet_start(SSH2_MSG_NEWKEYS);
204: packet_send();
205: /* packet_write_wait(); */
206: debug("SSH2_MSG_NEWKEYS sent");
1.19 stevesk 207:
1.52 markus 208: debug("expecting SSH2_MSG_NEWKEYS");
1.40 markus 209: packet_read_expect(SSH2_MSG_NEWKEYS);
1.46 markus 210: packet_check_eom();
1.26 markus 211: debug("SSH2_MSG_NEWKEYS received");
1.32 markus 212:
1.30 markus 213: kex->done = 1;
1.26 markus 214: buffer_clear(&kex->peer);
1.27 markus 215: /* buffer_clear(&kex->my); */
1.26 markus 216: kex->flags &= ~KEX_INIT_SENT;
1.91 ! djm 217: free(kex->name);
1.32 markus 218: kex->name = NULL;
1.26 markus 219: }
1.1 markus 220:
1.26 markus 221: void
222: kex_send_kexinit(Kex *kex)
223: {
1.60 avsm 224: u_int32_t rnd = 0;
1.49 markus 225: u_char *cookie;
1.61 djm 226: u_int i;
1.49 markus 227:
1.29 markus 228: if (kex == NULL) {
229: error("kex_send_kexinit: no kex, cannot rekey");
230: return;
231: }
1.28 markus 232: if (kex->flags & KEX_INIT_SENT) {
233: debug("KEX_INIT_SENT");
234: return;
235: }
1.30 markus 236: kex->done = 0;
1.49 markus 237:
238: /* generate a random cookie */
239: if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
240: fatal("kex_send_kexinit: kex proposal too short");
241: cookie = buffer_ptr(&kex->my);
242: for (i = 0; i < KEX_COOKIE_LEN; i++) {
243: if (i % 4 == 0)
1.60 avsm 244: rnd = arc4random();
245: cookie[i] = rnd;
246: rnd >>= 8;
1.49 markus 247: }
1.26 markus 248: packet_start(SSH2_MSG_KEXINIT);
249: packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
250: packet_send();
251: debug("SSH2_MSG_KEXINIT sent");
252: kex->flags |= KEX_INIT_SENT;
1.1 markus 253: }
254:
1.78 djm 255: /* ARGSUSED */
1.26 markus 256: void
1.41 markus 257: kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
1.11 provos 258: {
1.26 markus 259: char *ptr;
1.61 djm 260: u_int i, dlen;
1.26 markus 261: Kex *kex = (Kex *)ctxt;
1.11 provos 262:
1.26 markus 263: debug("SSH2_MSG_KEXINIT received");
1.29 markus 264: if (kex == NULL)
265: fatal("kex_input_kexinit: no kex, cannot rekey");
1.11 provos 266:
1.26 markus 267: ptr = packet_get_raw(&dlen);
268: buffer_append(&kex->peer, ptr, dlen);
1.31 markus 269:
270: /* discard packet */
271: for (i = 0; i < KEX_COOKIE_LEN; i++)
272: packet_get_char();
273: for (i = 0; i < PROPOSAL_MAX; i++)
1.91 ! djm 274: free(packet_get_string(NULL));
1.87 djm 275: /*
276: * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
277: * KEX method has the server move first, but a server might be using
278: * a custom method or one that we otherwise don't support. We should
279: * be prepared to remember first_kex_follows here so we can eat a
280: * packet later.
281: * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
282: * for cases where the server *doesn't* go first. I guess we should
283: * ignore it when it is set for these cases, which is what we do now.
284: */
285: (void) packet_get_char(); /* first_kex_follows */
286: (void) packet_get_int(); /* reserved */
1.39 markus 287: packet_check_eom();
1.19 stevesk 288:
1.26 markus 289: kex_kexinit_finish(kex);
290: }
1.11 provos 291:
1.26 markus 292: Kex *
1.28 markus 293: kex_setup(char *proposal[PROPOSAL_MAX])
1.26 markus 294: {
295: Kex *kex;
1.11 provos 296:
1.70 djm 297: kex = xcalloc(1, sizeof(*kex));
1.26 markus 298: buffer_init(&kex->peer);
299: buffer_init(&kex->my);
300: kex_prop2buf(&kex->my, proposal);
1.30 markus 301: kex->done = 0;
1.26 markus 302:
303: kex_send_kexinit(kex); /* we start */
1.44 markus 304: kex_reset_dispatch();
1.26 markus 305:
306: return kex;
1.11 provos 307: }
308:
1.35 itojun 309: static void
1.26 markus 310: kex_kexinit_finish(Kex *kex)
1.1 markus 311: {
1.26 markus 312: if (!(kex->flags & KEX_INIT_SENT))
313: kex_send_kexinit(kex);
1.1 markus 314:
1.26 markus 315: kex_choose_conf(kex);
1.1 markus 316:
1.54 markus 317: if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
318: kex->kex[kex->kex_type] != NULL) {
319: (kex->kex[kex->kex_type])(kex);
320: } else {
1.26 markus 321: fatal("Unsupported key exchange %d", kex->kex_type);
1.1 markus 322: }
323: }
324:
1.35 itojun 325: static void
1.1 markus 326: choose_enc(Enc *enc, char *client, char *server)
327: {
1.23 markus 328: char *name = match_list(client, server, NULL);
1.1 markus 329: if (name == NULL)
1.78 djm 330: fatal("no matching cipher found: client %s server %s",
331: client, server);
1.45 markus 332: if ((enc->cipher = cipher_by_name(name)) == NULL)
1.12 markus 333: fatal("matching cipher is not supported: %s", name);
1.1 markus 334: enc->name = name;
335: enc->enabled = 0;
336: enc->iv = NULL;
1.88 markus 337: enc->iv_len = cipher_ivlen(enc->cipher);
1.1 markus 338: enc->key = NULL;
1.45 markus 339: enc->key_len = cipher_keylen(enc->cipher);
340: enc->block_size = cipher_blocksize(enc->cipher);
1.1 markus 341: }
1.69 deraadt 342:
1.35 itojun 343: static void
1.1 markus 344: choose_mac(Mac *mac, char *client, char *server)
345: {
1.23 markus 346: char *name = match_list(client, server, NULL);
1.1 markus 347: if (name == NULL)
1.78 djm 348: fatal("no matching mac found: client %s server %s",
349: client, server);
1.79 djm 350: if (mac_setup(mac, name) < 0)
1.1 markus 351: fatal("unsupported mac %s", name);
1.21 markus 352: /* truncate the key */
353: if (datafellows & SSH_BUG_HMAC)
354: mac->key_len = 16;
1.1 markus 355: mac->name = name;
356: mac->key = NULL;
357: mac->enabled = 0;
358: }
1.69 deraadt 359:
1.35 itojun 360: static void
1.1 markus 361: choose_comp(Comp *comp, char *client, char *server)
362: {
1.23 markus 363: char *name = match_list(client, server, NULL);
1.1 markus 364: if (name == NULL)
365: fatal("no matching comp found: client %s server %s", client, server);
1.64 markus 366: if (strcmp(name, "zlib@openssh.com") == 0) {
367: comp->type = COMP_DELAYED;
368: } else if (strcmp(name, "zlib") == 0) {
369: comp->type = COMP_ZLIB;
1.1 markus 370: } else if (strcmp(name, "none") == 0) {
1.64 markus 371: comp->type = COMP_NONE;
1.1 markus 372: } else {
373: fatal("unsupported comp %s", name);
374: }
375: comp->name = name;
376: }
1.69 deraadt 377:
1.35 itojun 378: static void
1.1 markus 379: choose_kex(Kex *k, char *client, char *server)
380: {
1.89 djm 381: const struct kexalg *kexalg;
382:
1.23 markus 383: k->name = match_list(client, server, NULL);
1.1 markus 384: if (k->name == NULL)
1.78 djm 385: fatal("Unable to negotiate a key exchange method");
1.89 djm 386: if ((kexalg = kex_alg_by_name(k->name)) == NULL)
387: fatal("unsupported kex alg %s", k->name);
388: k->kex_type = kexalg->type;
389: k->evp_md = kexalg->mdfunc();
390: k->ec_nid = kexalg->ec_nid;
1.1 markus 391: }
1.65 djm 392:
1.35 itojun 393: static void
1.1 markus 394: choose_hostkeyalg(Kex *k, char *client, char *server)
395: {
1.23 markus 396: char *hostkeyalg = match_list(client, server, NULL);
1.13 markus 397: if (hostkeyalg == NULL)
1.1 markus 398: fatal("no hostkey alg");
1.13 markus 399: k->hostkey_type = key_type_from_name(hostkeyalg);
400: if (k->hostkey_type == KEY_UNSPEC)
401: fatal("bad hostkey alg '%s'", hostkeyalg);
1.91 ! djm 402: free(hostkeyalg);
1.1 markus 403: }
404:
1.56 djm 405: static int
1.53 markus 406: proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
407: {
408: static int check[] = {
409: PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
410: };
411: int *idx;
412: char *p;
413:
414: for (idx = &check[0]; *idx != -1; idx++) {
415: if ((p = strchr(my[*idx], ',')) != NULL)
416: *p = '\0';
417: if ((p = strchr(peer[*idx], ',')) != NULL)
418: *p = '\0';
419: if (strcmp(my[*idx], peer[*idx]) != 0) {
420: debug2("proposal mismatch: my %s peer %s",
421: my[*idx], peer[*idx]);
422: return (0);
423: }
424: }
425: debug2("proposals match");
426: return (1);
427: }
428:
1.35 itojun 429: static void
1.27 markus 430: kex_choose_conf(Kex *kex)
1.1 markus 431: {
1.27 markus 432: Newkeys *newkeys;
1.26 markus 433: char **my, **peer;
434: char **cprop, **sprop;
1.27 markus 435: int nenc, nmac, ncomp;
1.88 markus 436: u_int mode, ctos, need, authlen;
1.53 markus 437: int first_kex_follows, type;
1.1 markus 438:
1.53 markus 439: my = kex_buf2prop(&kex->my, NULL);
440: peer = kex_buf2prop(&kex->peer, &first_kex_follows);
1.26 markus 441:
1.27 markus 442: if (kex->server) {
1.26 markus 443: cprop=peer;
444: sprop=my;
445: } else {
446: cprop=my;
447: sprop=peer;
1.82 andreas 448: }
449:
450: /* Check whether server offers roaming */
451: if (!kex->server) {
452: char *roaming;
453: roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL);
454: if (roaming) {
455: kex->roaming = 1;
1.91 ! djm 456: free(roaming);
1.82 andreas 457: }
1.26 markus 458: }
1.1 markus 459:
1.30 markus 460: /* Algorithm Negotiation */
1.1 markus 461: for (mode = 0; mode < MODE_MAX; mode++) {
1.70 djm 462: newkeys = xcalloc(1, sizeof(*newkeys));
1.30 markus 463: kex->newkeys[mode] = newkeys;
1.78 djm 464: ctos = (!kex->server && mode == MODE_OUT) ||
465: (kex->server && mode == MODE_IN);
1.1 markus 466: nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
467: nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
468: ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
1.88 markus 469: choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]);
470: /* ignore mac for authenticated encryption */
471: authlen = cipher_authlen(newkeys->enc.cipher);
472: if (authlen == 0)
473: choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]);
1.27 markus 474: choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
1.2 markus 475: debug("kex: %s %s %s %s",
1.1 markus 476: ctos ? "client->server" : "server->client",
1.27 markus 477: newkeys->enc.name,
1.88 markus 478: authlen == 0 ? newkeys->mac.name : "<implicit>",
1.27 markus 479: newkeys->comp.name);
1.1 markus 480: }
1.27 markus 481: choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
482: choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
1.1 markus 483: sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
484: need = 0;
485: for (mode = 0; mode < MODE_MAX; mode++) {
1.30 markus 486: newkeys = kex->newkeys[mode];
1.45 markus 487: if (need < newkeys->enc.key_len)
488: need = newkeys->enc.key_len;
489: if (need < newkeys->enc.block_size)
490: need = newkeys->enc.block_size;
1.88 markus 491: if (need < newkeys->enc.iv_len)
492: need = newkeys->enc.iv_len;
1.27 markus 493: if (need < newkeys->mac.key_len)
494: need = newkeys->mac.key_len;
1.1 markus 495: }
1.7 markus 496: /* XXX need runden? */
1.27 markus 497: kex->we_need = need;
1.53 markus 498:
499: /* ignore the next message if the proposals do not match */
1.56 djm 500: if (first_kex_follows && !proposals_match(my, peer) &&
1.63 djm 501: !(datafellows & SSH_BUG_FIRSTKEX)) {
1.53 markus 502: type = packet_read();
503: debug2("skipping next packet (type %u)", type);
504: }
1.26 markus 505:
506: kex_prop_free(my);
507: kex_prop_free(peer);
508: }
509:
1.35 itojun 510: static u_char *
1.65 djm 511: derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen,
512: BIGNUM *shared_secret)
1.26 markus 513: {
514: Buffer b;
515: EVP_MD_CTX md;
516: char c = id;
1.61 djm 517: u_int have;
1.65 djm 518: int mdsz;
1.61 djm 519: u_char *digest;
1.62 djm 520:
1.65 djm 521: if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0)
522: fatal("bad kex md size %d", mdsz);
1.68 deraadt 523: digest = xmalloc(roundup(need, mdsz));
1.26 markus 524:
525: buffer_init(&b);
526: buffer_put_bignum2(&b, shared_secret);
527:
1.30 markus 528: /* K1 = HASH(K || H || "A" || session_id) */
1.65 djm 529: EVP_DigestInit(&md, kex->evp_md);
1.34 markus 530: if (!(datafellows & SSH_BUG_DERIVEKEY))
531: EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
1.65 djm 532: EVP_DigestUpdate(&md, hash, hashlen);
1.30 markus 533: EVP_DigestUpdate(&md, &c, 1);
1.27 markus 534: EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len);
1.26 markus 535: EVP_DigestFinal(&md, digest, NULL);
536:
1.30 markus 537: /*
538: * expand key:
539: * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
540: * Key = K1 || K2 || ... || Kn
541: */
1.26 markus 542: for (have = mdsz; need > have; have += mdsz) {
1.65 djm 543: EVP_DigestInit(&md, kex->evp_md);
1.34 markus 544: if (!(datafellows & SSH_BUG_DERIVEKEY))
545: EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
1.65 djm 546: EVP_DigestUpdate(&md, hash, hashlen);
1.26 markus 547: EVP_DigestUpdate(&md, digest, have);
548: EVP_DigestFinal(&md, digest + have, NULL);
549: }
550: buffer_free(&b);
551: #ifdef DEBUG_KEX
552: fprintf(stderr, "key '%c'== ", c);
553: dump_digest("key", digest, need);
554: #endif
555: return digest;
1.1 markus 556: }
557:
1.30 markus 558: Newkeys *current_keys[MODE_MAX];
1.27 markus 559:
1.23 markus 560: #define NKEYS 6
1.26 markus 561: void
1.65 djm 562: kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret)
1.1 markus 563: {
1.15 markus 564: u_char *keys[NKEYS];
1.61 djm 565: u_int i, mode, ctos;
1.1 markus 566:
1.65 djm 567: for (i = 0; i < NKEYS; i++) {
568: keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen,
569: shared_secret);
570: }
1.1 markus 571:
1.52 markus 572: debug2("kex_derive_keys");
1.1 markus 573: for (mode = 0; mode < MODE_MAX; mode++) {
1.30 markus 574: current_keys[mode] = kex->newkeys[mode];
575: kex->newkeys[mode] = NULL;
1.69 deraadt 576: ctos = (!kex->server && mode == MODE_OUT) ||
577: (kex->server && mode == MODE_IN);
1.30 markus 578: current_keys[mode]->enc.iv = keys[ctos ? 0 : 1];
579: current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
580: current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
1.1 markus 581: }
1.27 markus 582: }
583:
584: Newkeys *
585: kex_get_newkeys(int mode)
586: {
1.30 markus 587: Newkeys *ret;
588:
589: ret = current_keys[mode];
590: current_keys[mode] = NULL;
591: return ret;
1.57 djm 592: }
593:
594: void
595: derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
596: u_int8_t cookie[8], u_int8_t id[16])
597: {
598: const EVP_MD *evp_md = EVP_md5();
599: EVP_MD_CTX md;
600: u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE];
601: int len;
602:
603: EVP_DigestInit(&md, evp_md);
604:
605: len = BN_num_bytes(host_modulus);
1.61 djm 606: if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
1.57 djm 607: fatal("%s: bad host modulus (len %d)", __func__, len);
608: BN_bn2bin(host_modulus, nbuf);
609: EVP_DigestUpdate(&md, nbuf, len);
610:
611: len = BN_num_bytes(server_modulus);
1.61 djm 612: if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
1.57 djm 613: fatal("%s: bad server modulus (len %d)", __func__, len);
614: BN_bn2bin(server_modulus, nbuf);
615: EVP_DigestUpdate(&md, nbuf, len);
616:
617: EVP_DigestUpdate(&md, cookie, 8);
618:
1.58 djm 619: EVP_DigestFinal(&md, obuf, NULL);
1.57 djm 620: memcpy(id, obuf, 16);
621:
622: memset(nbuf, 0, sizeof(nbuf));
623: memset(obuf, 0, sizeof(obuf));
624: memset(&md, 0, sizeof(md));
1.1 markus 625: }
1.26 markus 626:
1.84 djm 627: #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
1.26 markus 628: void
629: dump_digest(char *msg, u_char *digest, int len)
630: {
1.84 djm 631: int i;
1.26 markus 632:
633: fprintf(stderr, "%s\n", msg);
1.77 stevesk 634: for (i = 0; i < len; i++) {
1.26 markus 635: fprintf(stderr, "%02x", digest[i]);
636: if (i%32 == 31)
637: fprintf(stderr, "\n");
638: else if (i%8 == 7)
639: fprintf(stderr, " ");
640: }
641: fprintf(stderr, "\n");
642: }
643: #endif
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