Annotation of src/usr.bin/ssh/kex.c, Revision 1.94
1.94 ! djm 1: /* $OpenBSD: kex.c,v 1.93 2013/11/07 11:58:27 dtucker 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"
1.94 ! djm 49: #include "digest.h"
1.48 provos 50:
1.35 itojun 51: /* prototype */
52: static void kex_kexinit_finish(Kex *);
53: static void kex_choose_conf(Kex *);
1.86 djm 54:
1.89 djm 55: struct kexalg {
56: char *name;
57: int type;
58: int ec_nid;
1.94 ! djm 59: int hash_alg;
1.89 djm 60: };
61: static const struct kexalg kexalgs[] = {
1.94 ! djm 62: { KEX_DH1, KEX_DH_GRP1_SHA1, 0, SSH_DIGEST_SHA1 },
! 63: { KEX_DH14, KEX_DH_GRP14_SHA1, 0, SSH_DIGEST_SHA1 },
! 64: { KEX_DHGEX_SHA1, KEX_DH_GEX_SHA1, 0, SSH_DIGEST_SHA1 },
! 65: { KEX_DHGEX_SHA256, KEX_DH_GEX_SHA256, 0, SSH_DIGEST_SHA256 },
! 66: { KEX_ECDH_SHA2_NISTP256, KEX_ECDH_SHA2,
! 67: NID_X9_62_prime256v1, SSH_DIGEST_SHA256 },
! 68: { KEX_ECDH_SHA2_NISTP384, KEX_ECDH_SHA2, NID_secp384r1,
! 69: SSH_DIGEST_SHA384 },
! 70: { KEX_ECDH_SHA2_NISTP521, KEX_ECDH_SHA2, NID_secp521r1,
! 71: SSH_DIGEST_SHA512 },
! 72: { KEX_CURVE25519_SHA256, KEX_C25519_SHA256, 0, SSH_DIGEST_SHA256 },
! 73: { NULL, -1, -1, -1},
1.89 djm 74: };
75:
76: char *
1.93 dtucker 77: kex_alg_list(char sep)
1.89 djm 78: {
79: char *ret = NULL;
80: size_t nlen, rlen = 0;
81: const struct kexalg *k;
82:
83: for (k = kexalgs; k->name != NULL; k++) {
84: if (ret != NULL)
1.93 dtucker 85: ret[rlen++] = sep;
1.89 djm 86: nlen = strlen(k->name);
87: ret = xrealloc(ret, 1, rlen + nlen + 2);
88: memcpy(ret + rlen, k->name, nlen + 1);
89: rlen += nlen;
90: }
91: return ret;
92: }
93:
94: static const struct kexalg *
95: kex_alg_by_name(const char *name)
96: {
97: const struct kexalg *k;
98:
99: for (k = kexalgs; k->name != NULL; k++) {
100: if (strcmp(k->name, name) == 0)
101: return k;
102: }
103: return NULL;
104: }
105:
1.86 djm 106: /* Validate KEX method name list */
107: int
108: kex_names_valid(const char *names)
109: {
110: char *s, *cp, *p;
111:
112: if (names == NULL || strcmp(names, "") == 0)
113: return 0;
114: s = cp = xstrdup(names);
115: for ((p = strsep(&cp, ",")); p && *p != '\0';
116: (p = strsep(&cp, ","))) {
1.89 djm 117: if (kex_alg_by_name(p) == NULL) {
1.86 djm 118: error("Unsupported KEX algorithm \"%.100s\"", p);
1.91 djm 119: free(s);
1.86 djm 120: return 0;
121: }
122: }
123: debug3("kex names ok: [%s]", names);
1.91 djm 124: free(s);
1.86 djm 125: return 1;
126: }
1.26 markus 127:
128: /* put algorithm proposal into buffer */
1.35 itojun 129: static void
1.26 markus 130: kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX])
1.1 markus 131: {
1.61 djm 132: u_int i;
1.26 markus 133:
134: buffer_clear(b);
1.49 markus 135: /*
136: * add a dummy cookie, the cookie will be overwritten by
137: * kex_send_kexinit(), each time a kexinit is set
138: */
139: for (i = 0; i < KEX_COOKIE_LEN; i++)
140: buffer_put_char(b, 0);
1.1 markus 141: for (i = 0; i < PROPOSAL_MAX; i++)
1.26 markus 142: buffer_put_cstring(b, proposal[i]);
143: buffer_put_char(b, 0); /* first_kex_packet_follows */
144: buffer_put_int(b, 0); /* uint32 reserved */
1.1 markus 145: }
146:
1.26 markus 147: /* parse buffer and return algorithm proposal */
1.35 itojun 148: static char **
1.53 markus 149: kex_buf2prop(Buffer *raw, int *first_kex_follows)
1.7 markus 150: {
1.26 markus 151: Buffer b;
1.78 djm 152: u_int i;
1.26 markus 153: char **proposal;
1.7 markus 154:
1.70 djm 155: proposal = xcalloc(PROPOSAL_MAX, sizeof(char *));
1.7 markus 156:
1.26 markus 157: buffer_init(&b);
158: buffer_append(&b, buffer_ptr(raw), buffer_len(raw));
1.7 markus 159: /* skip cookie */
160: for (i = 0; i < KEX_COOKIE_LEN; i++)
1.26 markus 161: buffer_get_char(&b);
1.7 markus 162: /* extract kex init proposal strings */
163: for (i = 0; i < PROPOSAL_MAX; i++) {
1.83 djm 164: proposal[i] = buffer_get_cstring(&b,NULL);
1.26 markus 165: debug2("kex_parse_kexinit: %s", proposal[i]);
1.7 markus 166: }
1.26 markus 167: /* first kex follows / reserved */
168: i = buffer_get_char(&b);
1.53 markus 169: if (first_kex_follows != NULL)
170: *first_kex_follows = i;
1.26 markus 171: debug2("kex_parse_kexinit: first_kex_follows %d ", i);
172: i = buffer_get_int(&b);
1.78 djm 173: debug2("kex_parse_kexinit: reserved %u ", i);
1.26 markus 174: buffer_free(&b);
175: return proposal;
1.1 markus 176: }
177:
1.35 itojun 178: static void
1.26 markus 179: kex_prop_free(char **proposal)
1.1 markus 180: {
1.61 djm 181: u_int i;
1.26 markus 182:
183: for (i = 0; i < PROPOSAL_MAX; i++)
1.91 djm 184: free(proposal[i]);
185: free(proposal);
1.1 markus 186: }
187:
1.78 djm 188: /* ARGSUSED */
1.35 itojun 189: static void
1.41 markus 190: kex_protocol_error(int type, u_int32_t seq, void *ctxt)
1.1 markus 191: {
1.41 markus 192: error("Hm, kex protocol error: type %d seq %u", type, seq);
1.26 markus 193: }
1.1 markus 194:
1.35 itojun 195: static void
1.44 markus 196: kex_reset_dispatch(void)
1.29 markus 197: {
1.42 markus 198: dispatch_range(SSH2_MSG_TRANSPORT_MIN,
199: SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error);
1.44 markus 200: dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
1.29 markus 201: }
202:
203: void
1.28 markus 204: kex_finish(Kex *kex)
1.26 markus 205: {
1.44 markus 206: kex_reset_dispatch();
1.28 markus 207:
1.26 markus 208: packet_start(SSH2_MSG_NEWKEYS);
209: packet_send();
210: /* packet_write_wait(); */
211: debug("SSH2_MSG_NEWKEYS sent");
1.19 stevesk 212:
1.52 markus 213: debug("expecting SSH2_MSG_NEWKEYS");
1.40 markus 214: packet_read_expect(SSH2_MSG_NEWKEYS);
1.46 markus 215: packet_check_eom();
1.26 markus 216: debug("SSH2_MSG_NEWKEYS received");
1.32 markus 217:
1.30 markus 218: kex->done = 1;
1.26 markus 219: buffer_clear(&kex->peer);
1.27 markus 220: /* buffer_clear(&kex->my); */
1.26 markus 221: kex->flags &= ~KEX_INIT_SENT;
1.91 djm 222: free(kex->name);
1.32 markus 223: kex->name = NULL;
1.26 markus 224: }
1.1 markus 225:
1.26 markus 226: void
227: kex_send_kexinit(Kex *kex)
228: {
1.60 avsm 229: u_int32_t rnd = 0;
1.49 markus 230: u_char *cookie;
1.61 djm 231: u_int i;
1.49 markus 232:
1.29 markus 233: if (kex == NULL) {
234: error("kex_send_kexinit: no kex, cannot rekey");
235: return;
236: }
1.28 markus 237: if (kex->flags & KEX_INIT_SENT) {
238: debug("KEX_INIT_SENT");
239: return;
240: }
1.30 markus 241: kex->done = 0;
1.49 markus 242:
243: /* generate a random cookie */
244: if (buffer_len(&kex->my) < KEX_COOKIE_LEN)
245: fatal("kex_send_kexinit: kex proposal too short");
246: cookie = buffer_ptr(&kex->my);
247: for (i = 0; i < KEX_COOKIE_LEN; i++) {
248: if (i % 4 == 0)
1.60 avsm 249: rnd = arc4random();
250: cookie[i] = rnd;
251: rnd >>= 8;
1.49 markus 252: }
1.26 markus 253: packet_start(SSH2_MSG_KEXINIT);
254: packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my));
255: packet_send();
256: debug("SSH2_MSG_KEXINIT sent");
257: kex->flags |= KEX_INIT_SENT;
1.1 markus 258: }
259:
1.78 djm 260: /* ARGSUSED */
1.26 markus 261: void
1.41 markus 262: kex_input_kexinit(int type, u_int32_t seq, void *ctxt)
1.11 provos 263: {
1.26 markus 264: char *ptr;
1.61 djm 265: u_int i, dlen;
1.26 markus 266: Kex *kex = (Kex *)ctxt;
1.11 provos 267:
1.26 markus 268: debug("SSH2_MSG_KEXINIT received");
1.29 markus 269: if (kex == NULL)
270: fatal("kex_input_kexinit: no kex, cannot rekey");
1.11 provos 271:
1.26 markus 272: ptr = packet_get_raw(&dlen);
273: buffer_append(&kex->peer, ptr, dlen);
1.31 markus 274:
275: /* discard packet */
276: for (i = 0; i < KEX_COOKIE_LEN; i++)
277: packet_get_char();
278: for (i = 0; i < PROPOSAL_MAX; i++)
1.91 djm 279: free(packet_get_string(NULL));
1.87 djm 280: /*
281: * XXX RFC4253 sec 7: "each side MAY guess" - currently no supported
282: * KEX method has the server move first, but a server might be using
283: * a custom method or one that we otherwise don't support. We should
284: * be prepared to remember first_kex_follows here so we can eat a
285: * packet later.
286: * XXX2 - RFC4253 is kind of ambiguous on what first_kex_follows means
287: * for cases where the server *doesn't* go first. I guess we should
288: * ignore it when it is set for these cases, which is what we do now.
289: */
290: (void) packet_get_char(); /* first_kex_follows */
291: (void) packet_get_int(); /* reserved */
1.39 markus 292: packet_check_eom();
1.19 stevesk 293:
1.26 markus 294: kex_kexinit_finish(kex);
295: }
1.11 provos 296:
1.26 markus 297: Kex *
1.28 markus 298: kex_setup(char *proposal[PROPOSAL_MAX])
1.26 markus 299: {
300: Kex *kex;
1.11 provos 301:
1.70 djm 302: kex = xcalloc(1, sizeof(*kex));
1.26 markus 303: buffer_init(&kex->peer);
304: buffer_init(&kex->my);
305: kex_prop2buf(&kex->my, proposal);
1.30 markus 306: kex->done = 0;
1.26 markus 307:
308: kex_send_kexinit(kex); /* we start */
1.44 markus 309: kex_reset_dispatch();
1.26 markus 310:
311: return kex;
1.11 provos 312: }
313:
1.35 itojun 314: static void
1.26 markus 315: kex_kexinit_finish(Kex *kex)
1.1 markus 316: {
1.26 markus 317: if (!(kex->flags & KEX_INIT_SENT))
318: kex_send_kexinit(kex);
1.1 markus 319:
1.26 markus 320: kex_choose_conf(kex);
1.1 markus 321:
1.54 markus 322: if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX &&
323: kex->kex[kex->kex_type] != NULL) {
324: (kex->kex[kex->kex_type])(kex);
325: } else {
1.26 markus 326: fatal("Unsupported key exchange %d", kex->kex_type);
1.1 markus 327: }
328: }
329:
1.35 itojun 330: static void
1.1 markus 331: choose_enc(Enc *enc, char *client, char *server)
332: {
1.23 markus 333: char *name = match_list(client, server, NULL);
1.1 markus 334: if (name == NULL)
1.78 djm 335: fatal("no matching cipher found: client %s server %s",
336: client, server);
1.45 markus 337: if ((enc->cipher = cipher_by_name(name)) == NULL)
1.12 markus 338: fatal("matching cipher is not supported: %s", name);
1.1 markus 339: enc->name = name;
340: enc->enabled = 0;
341: enc->iv = NULL;
1.88 markus 342: enc->iv_len = cipher_ivlen(enc->cipher);
1.1 markus 343: enc->key = NULL;
1.45 markus 344: enc->key_len = cipher_keylen(enc->cipher);
345: enc->block_size = cipher_blocksize(enc->cipher);
1.1 markus 346: }
1.69 deraadt 347:
1.35 itojun 348: static void
1.1 markus 349: choose_mac(Mac *mac, char *client, char *server)
350: {
1.23 markus 351: char *name = match_list(client, server, NULL);
1.1 markus 352: if (name == NULL)
1.78 djm 353: fatal("no matching mac found: client %s server %s",
354: client, server);
1.79 djm 355: if (mac_setup(mac, name) < 0)
1.1 markus 356: fatal("unsupported mac %s", name);
1.21 markus 357: /* truncate the key */
358: if (datafellows & SSH_BUG_HMAC)
359: mac->key_len = 16;
1.1 markus 360: mac->name = name;
361: mac->key = NULL;
362: mac->enabled = 0;
363: }
1.69 deraadt 364:
1.35 itojun 365: static void
1.1 markus 366: choose_comp(Comp *comp, char *client, char *server)
367: {
1.23 markus 368: char *name = match_list(client, server, NULL);
1.1 markus 369: if (name == NULL)
370: fatal("no matching comp found: client %s server %s", client, server);
1.64 markus 371: if (strcmp(name, "zlib@openssh.com") == 0) {
372: comp->type = COMP_DELAYED;
373: } else if (strcmp(name, "zlib") == 0) {
374: comp->type = COMP_ZLIB;
1.1 markus 375: } else if (strcmp(name, "none") == 0) {
1.64 markus 376: comp->type = COMP_NONE;
1.1 markus 377: } else {
378: fatal("unsupported comp %s", name);
379: }
380: comp->name = name;
381: }
1.69 deraadt 382:
1.35 itojun 383: static void
1.1 markus 384: choose_kex(Kex *k, char *client, char *server)
385: {
1.89 djm 386: const struct kexalg *kexalg;
387:
1.23 markus 388: k->name = match_list(client, server, NULL);
1.1 markus 389: if (k->name == NULL)
1.78 djm 390: fatal("Unable to negotiate a key exchange method");
1.89 djm 391: if ((kexalg = kex_alg_by_name(k->name)) == NULL)
392: fatal("unsupported kex alg %s", k->name);
393: k->kex_type = kexalg->type;
1.94 ! djm 394: k->hash_alg = kexalg->hash_alg;
1.89 djm 395: k->ec_nid = kexalg->ec_nid;
1.1 markus 396: }
1.65 djm 397:
1.35 itojun 398: static void
1.1 markus 399: choose_hostkeyalg(Kex *k, char *client, char *server)
400: {
1.23 markus 401: char *hostkeyalg = match_list(client, server, NULL);
1.13 markus 402: if (hostkeyalg == NULL)
1.1 markus 403: fatal("no hostkey alg");
1.13 markus 404: k->hostkey_type = key_type_from_name(hostkeyalg);
405: if (k->hostkey_type == KEY_UNSPEC)
406: fatal("bad hostkey alg '%s'", hostkeyalg);
1.91 djm 407: free(hostkeyalg);
1.1 markus 408: }
409:
1.56 djm 410: static int
1.53 markus 411: proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX])
412: {
413: static int check[] = {
414: PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1
415: };
416: int *idx;
417: char *p;
418:
419: for (idx = &check[0]; *idx != -1; idx++) {
420: if ((p = strchr(my[*idx], ',')) != NULL)
421: *p = '\0';
422: if ((p = strchr(peer[*idx], ',')) != NULL)
423: *p = '\0';
424: if (strcmp(my[*idx], peer[*idx]) != 0) {
425: debug2("proposal mismatch: my %s peer %s",
426: my[*idx], peer[*idx]);
427: return (0);
428: }
429: }
430: debug2("proposals match");
431: return (1);
432: }
433:
1.35 itojun 434: static void
1.27 markus 435: kex_choose_conf(Kex *kex)
1.1 markus 436: {
1.27 markus 437: Newkeys *newkeys;
1.26 markus 438: char **my, **peer;
439: char **cprop, **sprop;
1.27 markus 440: int nenc, nmac, ncomp;
1.88 markus 441: u_int mode, ctos, need, authlen;
1.53 markus 442: int first_kex_follows, type;
1.1 markus 443:
1.53 markus 444: my = kex_buf2prop(&kex->my, NULL);
445: peer = kex_buf2prop(&kex->peer, &first_kex_follows);
1.26 markus 446:
1.27 markus 447: if (kex->server) {
1.26 markus 448: cprop=peer;
449: sprop=my;
450: } else {
451: cprop=my;
452: sprop=peer;
1.82 andreas 453: }
454:
455: /* Check whether server offers roaming */
456: if (!kex->server) {
457: char *roaming;
458: roaming = match_list(KEX_RESUME, peer[PROPOSAL_KEX_ALGS], NULL);
459: if (roaming) {
460: kex->roaming = 1;
1.91 djm 461: free(roaming);
1.82 andreas 462: }
1.26 markus 463: }
1.1 markus 464:
1.30 markus 465: /* Algorithm Negotiation */
1.1 markus 466: for (mode = 0; mode < MODE_MAX; mode++) {
1.70 djm 467: newkeys = xcalloc(1, sizeof(*newkeys));
1.30 markus 468: kex->newkeys[mode] = newkeys;
1.78 djm 469: ctos = (!kex->server && mode == MODE_OUT) ||
470: (kex->server && mode == MODE_IN);
1.1 markus 471: nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC;
472: nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC;
473: ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC;
1.88 markus 474: choose_enc(&newkeys->enc, cprop[nenc], sprop[nenc]);
475: /* ignore mac for authenticated encryption */
476: authlen = cipher_authlen(newkeys->enc.cipher);
477: if (authlen == 0)
478: choose_mac(&newkeys->mac, cprop[nmac], sprop[nmac]);
1.27 markus 479: choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]);
1.2 markus 480: debug("kex: %s %s %s %s",
1.1 markus 481: ctos ? "client->server" : "server->client",
1.27 markus 482: newkeys->enc.name,
1.88 markus 483: authlen == 0 ? newkeys->mac.name : "<implicit>",
1.27 markus 484: newkeys->comp.name);
1.1 markus 485: }
1.27 markus 486: choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]);
487: choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS],
1.1 markus 488: sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]);
489: need = 0;
490: for (mode = 0; mode < MODE_MAX; mode++) {
1.30 markus 491: newkeys = kex->newkeys[mode];
1.45 markus 492: if (need < newkeys->enc.key_len)
493: need = newkeys->enc.key_len;
494: if (need < newkeys->enc.block_size)
495: need = newkeys->enc.block_size;
1.88 markus 496: if (need < newkeys->enc.iv_len)
497: need = newkeys->enc.iv_len;
1.27 markus 498: if (need < newkeys->mac.key_len)
499: need = newkeys->mac.key_len;
1.1 markus 500: }
1.7 markus 501: /* XXX need runden? */
1.27 markus 502: kex->we_need = need;
1.53 markus 503:
504: /* ignore the next message if the proposals do not match */
1.56 djm 505: if (first_kex_follows && !proposals_match(my, peer) &&
1.63 djm 506: !(datafellows & SSH_BUG_FIRSTKEX)) {
1.53 markus 507: type = packet_read();
508: debug2("skipping next packet (type %u)", type);
509: }
1.26 markus 510:
511: kex_prop_free(my);
512: kex_prop_free(peer);
513: }
514:
1.35 itojun 515: static u_char *
1.65 djm 516: derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen,
517: BIGNUM *shared_secret)
1.26 markus 518: {
519: Buffer b;
1.94 ! djm 520: struct ssh_digest_ctx *hashctx;
1.26 markus 521: char c = id;
1.61 djm 522: u_int have;
1.94 ! djm 523: size_t mdsz;
1.61 djm 524: u_char *digest;
1.62 djm 525:
1.94 ! djm 526: if ((mdsz = ssh_digest_bytes(kex->hash_alg)) == 0)
! 527: fatal("bad kex md size %zu", mdsz);
1.68 deraadt 528: digest = xmalloc(roundup(need, mdsz));
1.26 markus 529:
530: buffer_init(&b);
531: buffer_put_bignum2(&b, shared_secret);
532:
1.30 markus 533: /* K1 = HASH(K || H || "A" || session_id) */
1.94 ! djm 534: if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL)
! 535: fatal("%s: ssh_digest_start failed", __func__);
! 536: if (ssh_digest_update_buffer(hashctx, &b) != 0 ||
! 537: ssh_digest_update(hashctx, hash, hashlen) != 0 ||
! 538: ssh_digest_update(hashctx, &c, 1) != 0 ||
! 539: ssh_digest_update(hashctx, kex->session_id,
! 540: kex->session_id_len) != 0)
! 541: fatal("%s: ssh_digest_update failed", __func__);
! 542: if (ssh_digest_final(hashctx, digest, mdsz) != 0)
! 543: fatal("%s: ssh_digest_final failed", __func__);
! 544: ssh_digest_free(hashctx);
1.26 markus 545:
1.30 markus 546: /*
547: * expand key:
548: * Kn = HASH(K || H || K1 || K2 || ... || Kn-1)
549: * Key = K1 || K2 || ... || Kn
550: */
1.26 markus 551: for (have = mdsz; need > have; have += mdsz) {
1.94 ! djm 552: if ((hashctx = ssh_digest_start(kex->hash_alg)) == NULL)
! 553: fatal("%s: ssh_digest_start failed", __func__);
! 554: if (ssh_digest_update_buffer(hashctx, &b) != 0 ||
! 555: ssh_digest_update(hashctx, hash, hashlen) != 0 ||
! 556: ssh_digest_update(hashctx, digest, have) != 0)
! 557: fatal("%s: ssh_digest_update failed", __func__);
! 558: if (ssh_digest_final(hashctx, digest + have, mdsz) != 0)
! 559: fatal("%s: ssh_digest_final failed", __func__);
! 560: ssh_digest_free(hashctx);
1.26 markus 561: }
562: buffer_free(&b);
563: #ifdef DEBUG_KEX
564: fprintf(stderr, "key '%c'== ", c);
565: dump_digest("key", digest, need);
566: #endif
567: return digest;
1.1 markus 568: }
569:
1.30 markus 570: Newkeys *current_keys[MODE_MAX];
1.27 markus 571:
1.23 markus 572: #define NKEYS 6
1.26 markus 573: void
1.65 djm 574: kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret)
1.1 markus 575: {
1.15 markus 576: u_char *keys[NKEYS];
1.61 djm 577: u_int i, mode, ctos;
1.1 markus 578:
1.65 djm 579: for (i = 0; i < NKEYS; i++) {
580: keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen,
581: shared_secret);
582: }
1.1 markus 583:
1.52 markus 584: debug2("kex_derive_keys");
1.1 markus 585: for (mode = 0; mode < MODE_MAX; mode++) {
1.30 markus 586: current_keys[mode] = kex->newkeys[mode];
587: kex->newkeys[mode] = NULL;
1.69 deraadt 588: ctos = (!kex->server && mode == MODE_OUT) ||
589: (kex->server && mode == MODE_IN);
1.30 markus 590: current_keys[mode]->enc.iv = keys[ctos ? 0 : 1];
591: current_keys[mode]->enc.key = keys[ctos ? 2 : 3];
592: current_keys[mode]->mac.key = keys[ctos ? 4 : 5];
1.1 markus 593: }
1.27 markus 594: }
595:
596: Newkeys *
597: kex_get_newkeys(int mode)
598: {
1.30 markus 599: Newkeys *ret;
600:
601: ret = current_keys[mode];
602: current_keys[mode] = NULL;
603: return ret;
1.57 djm 604: }
605:
606: void
607: derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus,
608: u_int8_t cookie[8], u_int8_t id[16])
609: {
1.94 ! djm 610: u_int8_t nbuf[2048], obuf[SSH_DIGEST_MAX_LENGTH];
1.57 djm 611: int len;
1.94 ! djm 612: struct ssh_digest_ctx *hashctx;
1.57 djm 613:
1.94 ! djm 614: if ((hashctx = ssh_digest_start(SSH_DIGEST_MD5)) == NULL)
! 615: fatal("%s: ssh_digest_start", __func__);
1.57 djm 616:
617: len = BN_num_bytes(host_modulus);
1.61 djm 618: if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
1.57 djm 619: fatal("%s: bad host modulus (len %d)", __func__, len);
620: BN_bn2bin(host_modulus, nbuf);
1.94 ! djm 621: if (ssh_digest_update(hashctx, nbuf, len) != 0)
! 622: fatal("%s: ssh_digest_update failed", __func__);
1.57 djm 623:
624: len = BN_num_bytes(server_modulus);
1.61 djm 625: if (len < (512 / 8) || (u_int)len > sizeof(nbuf))
1.57 djm 626: fatal("%s: bad server modulus (len %d)", __func__, len);
627: BN_bn2bin(server_modulus, nbuf);
1.94 ! djm 628: if (ssh_digest_update(hashctx, nbuf, len) != 0 ||
! 629: ssh_digest_update(hashctx, cookie, 8) != 0)
! 630: fatal("%s: ssh_digest_update failed", __func__);
! 631: if (ssh_digest_final(hashctx, obuf, sizeof(obuf)) != 0)
! 632: fatal("%s: ssh_digest_final failed", __func__);
! 633: memcpy(id, obuf, ssh_digest_bytes(SSH_DIGEST_MD5));
1.57 djm 634:
635: memset(nbuf, 0, sizeof(nbuf));
636: memset(obuf, 0, sizeof(obuf));
1.1 markus 637: }
1.26 markus 638:
1.84 djm 639: #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) || defined(DEBUG_KEXECDH)
1.26 markus 640: void
641: dump_digest(char *msg, u_char *digest, int len)
642: {
1.84 djm 643: int i;
1.26 markus 644:
645: fprintf(stderr, "%s\n", msg);
1.77 stevesk 646: for (i = 0; i < len; i++) {
1.26 markus 647: fprintf(stderr, "%02x", digest[i]);
648: if (i%32 == 31)
649: fprintf(stderr, "\n");
650: else if (i%8 == 7)
651: fprintf(stderr, " ");
652: }
653: fprintf(stderr, "\n");
654: }
655: #endif
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