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fa0f0f45 | 1 | /* $OpenBSD: kex.c,v 1.79 2007/06/05 06:52:37 djm Exp $ */ |
3c0ef626 | 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" | |
30460aeb | 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> | |
3c0ef626 | 35 | |
36 | #include <openssl/crypto.h> | |
37 | ||
3c0ef626 | 38 | #include "xmalloc.h" |
30460aeb | 39 | #include "ssh2.h" |
3c0ef626 | 40 | #include "buffer.h" |
3c0ef626 | 41 | #include "packet.h" |
42 | #include "compat.h" | |
43 | #include "cipher.h" | |
3c0ef626 | 44 | #include "key.h" |
30460aeb | 45 | #include "kex.h" |
3c0ef626 | 46 | #include "log.h" |
47 | #include "mac.h" | |
48 | #include "match.h" | |
49 | #include "dispatch.h" | |
350391c5 | 50 | #include "monitor.h" |
3c0ef626 | 51 | |
5598e598 | 52 | #ifdef GSSAPI |
53 | #include "ssh-gss.h" | |
54 | #endif | |
55 | ||
3c0ef626 | 56 | #define KEX_COOKIE_LEN 16 |
57 | ||
30460aeb | 58 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L |
59 | # if defined(HAVE_EVP_SHA256) | |
60 | # define evp_ssh_sha256 EVP_sha256 | |
61 | # else | |
62 | extern const EVP_MD *evp_ssh_sha256(void); | |
63 | # endif | |
64 | #endif | |
65 | ||
3c0ef626 | 66 | /* prototype */ |
67 | static void kex_kexinit_finish(Kex *); | |
68 | static void kex_choose_conf(Kex *); | |
69 | ||
70 | /* put algorithm proposal into buffer */ | |
6df46d40 | 71 | /* used in sshconnect.c as well as kex.c */ |
473db5ab | 72 | void |
3c0ef626 | 73 | kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) |
74 | { | |
2ce0bfe4 | 75 | u_int i; |
3c0ef626 | 76 | |
77 | buffer_clear(b); | |
350391c5 | 78 | /* |
79 | * add a dummy cookie, the cookie will be overwritten by | |
80 | * kex_send_kexinit(), each time a kexinit is set | |
81 | */ | |
82 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
83 | buffer_put_char(b, 0); | |
3c0ef626 | 84 | for (i = 0; i < PROPOSAL_MAX; i++) |
85 | buffer_put_cstring(b, proposal[i]); | |
86 | buffer_put_char(b, 0); /* first_kex_packet_follows */ | |
87 | buffer_put_int(b, 0); /* uint32 reserved */ | |
88 | } | |
89 | ||
90 | /* parse buffer and return algorithm proposal */ | |
91 | static char ** | |
8afc6a66 | 92 | kex_buf2prop(Buffer *raw, int *first_kex_follows) |
3c0ef626 | 93 | { |
94 | Buffer b; | |
fa0f0f45 | 95 | u_int i; |
3c0ef626 | 96 | char **proposal; |
97 | ||
30460aeb | 98 | proposal = xcalloc(PROPOSAL_MAX, sizeof(char *)); |
3c0ef626 | 99 | |
100 | buffer_init(&b); | |
101 | buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); | |
102 | /* skip cookie */ | |
103 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
104 | buffer_get_char(&b); | |
105 | /* extract kex init proposal strings */ | |
106 | for (i = 0; i < PROPOSAL_MAX; i++) { | |
107 | proposal[i] = buffer_get_string(&b,NULL); | |
108 | debug2("kex_parse_kexinit: %s", proposal[i]); | |
109 | } | |
110 | /* first kex follows / reserved */ | |
111 | i = buffer_get_char(&b); | |
8afc6a66 | 112 | if (first_kex_follows != NULL) |
113 | *first_kex_follows = i; | |
3c0ef626 | 114 | debug2("kex_parse_kexinit: first_kex_follows %d ", i); |
115 | i = buffer_get_int(&b); | |
fa0f0f45 | 116 | debug2("kex_parse_kexinit: reserved %u ", i); |
3c0ef626 | 117 | buffer_free(&b); |
118 | return proposal; | |
119 | } | |
120 | ||
121 | static void | |
122 | kex_prop_free(char **proposal) | |
123 | { | |
2ce0bfe4 | 124 | u_int i; |
3c0ef626 | 125 | |
126 | for (i = 0; i < PROPOSAL_MAX; i++) | |
127 | xfree(proposal[i]); | |
128 | xfree(proposal); | |
129 | } | |
130 | ||
fa0f0f45 | 131 | /* ARGSUSED */ |
3c0ef626 | 132 | static void |
e9702f7d | 133 | kex_protocol_error(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 134 | { |
e9702f7d | 135 | error("Hm, kex protocol error: type %d seq %u", type, seq); |
3c0ef626 | 136 | } |
137 | ||
138 | static void | |
e9702f7d | 139 | kex_reset_dispatch(void) |
3c0ef626 | 140 | { |
e9702f7d | 141 | dispatch_range(SSH2_MSG_TRANSPORT_MIN, |
142 | SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); | |
143 | dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); | |
3c0ef626 | 144 | } |
145 | ||
146 | void | |
147 | kex_finish(Kex *kex) | |
148 | { | |
e9702f7d | 149 | kex_reset_dispatch(); |
3c0ef626 | 150 | |
151 | packet_start(SSH2_MSG_NEWKEYS); | |
152 | packet_send(); | |
153 | /* packet_write_wait(); */ | |
154 | debug("SSH2_MSG_NEWKEYS sent"); | |
155 | ||
8afc6a66 | 156 | debug("expecting SSH2_MSG_NEWKEYS"); |
e9702f7d | 157 | packet_read_expect(SSH2_MSG_NEWKEYS); |
158 | packet_check_eom(); | |
3c0ef626 | 159 | debug("SSH2_MSG_NEWKEYS received"); |
160 | ||
161 | kex->done = 1; | |
162 | buffer_clear(&kex->peer); | |
163 | /* buffer_clear(&kex->my); */ | |
164 | kex->flags &= ~KEX_INIT_SENT; | |
165 | xfree(kex->name); | |
166 | kex->name = NULL; | |
167 | } | |
168 | ||
169 | void | |
170 | kex_send_kexinit(Kex *kex) | |
171 | { | |
7e82606e | 172 | u_int32_t rnd = 0; |
350391c5 | 173 | u_char *cookie; |
2ce0bfe4 | 174 | u_int i; |
350391c5 | 175 | |
3c0ef626 | 176 | if (kex == NULL) { |
177 | error("kex_send_kexinit: no kex, cannot rekey"); | |
178 | return; | |
179 | } | |
180 | if (kex->flags & KEX_INIT_SENT) { | |
181 | debug("KEX_INIT_SENT"); | |
182 | return; | |
183 | } | |
184 | kex->done = 0; | |
350391c5 | 185 | |
186 | /* generate a random cookie */ | |
187 | if (buffer_len(&kex->my) < KEX_COOKIE_LEN) | |
188 | fatal("kex_send_kexinit: kex proposal too short"); | |
189 | cookie = buffer_ptr(&kex->my); | |
190 | for (i = 0; i < KEX_COOKIE_LEN; i++) { | |
191 | if (i % 4 == 0) | |
7e82606e | 192 | rnd = arc4random(); |
193 | cookie[i] = rnd; | |
194 | rnd >>= 8; | |
350391c5 | 195 | } |
3c0ef626 | 196 | packet_start(SSH2_MSG_KEXINIT); |
197 | packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); | |
198 | packet_send(); | |
199 | debug("SSH2_MSG_KEXINIT sent"); | |
200 | kex->flags |= KEX_INIT_SENT; | |
201 | } | |
202 | ||
fa0f0f45 | 203 | /* ARGSUSED */ |
3c0ef626 | 204 | void |
e9702f7d | 205 | kex_input_kexinit(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 206 | { |
207 | char *ptr; | |
2ce0bfe4 | 208 | u_int i, dlen; |
3c0ef626 | 209 | Kex *kex = (Kex *)ctxt; |
210 | ||
211 | debug("SSH2_MSG_KEXINIT received"); | |
212 | if (kex == NULL) | |
213 | fatal("kex_input_kexinit: no kex, cannot rekey"); | |
214 | ||
215 | ptr = packet_get_raw(&dlen); | |
216 | buffer_append(&kex->peer, ptr, dlen); | |
217 | ||
218 | /* discard packet */ | |
219 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
220 | packet_get_char(); | |
221 | for (i = 0; i < PROPOSAL_MAX; i++) | |
222 | xfree(packet_get_string(NULL)); | |
276b07a3 | 223 | (void) packet_get_char(); |
224 | (void) packet_get_int(); | |
e9702f7d | 225 | packet_check_eom(); |
3c0ef626 | 226 | |
227 | kex_kexinit_finish(kex); | |
228 | } | |
229 | ||
230 | Kex * | |
231 | kex_setup(char *proposal[PROPOSAL_MAX]) | |
232 | { | |
233 | Kex *kex; | |
234 | ||
30460aeb | 235 | kex = xcalloc(1, sizeof(*kex)); |
3c0ef626 | 236 | buffer_init(&kex->peer); |
237 | buffer_init(&kex->my); | |
238 | kex_prop2buf(&kex->my, proposal); | |
239 | kex->done = 0; | |
240 | ||
241 | kex_send_kexinit(kex); /* we start */ | |
e9702f7d | 242 | kex_reset_dispatch(); |
3c0ef626 | 243 | |
244 | return kex; | |
245 | } | |
246 | ||
247 | static void | |
248 | kex_kexinit_finish(Kex *kex) | |
249 | { | |
250 | if (!(kex->flags & KEX_INIT_SENT)) | |
251 | kex_send_kexinit(kex); | |
252 | ||
253 | kex_choose_conf(kex); | |
254 | ||
8afc6a66 | 255 | if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX && |
256 | kex->kex[kex->kex_type] != NULL) { | |
257 | (kex->kex[kex->kex_type])(kex); | |
258 | } else { | |
3c0ef626 | 259 | fatal("Unsupported key exchange %d", kex->kex_type); |
260 | } | |
261 | } | |
262 | ||
263 | static void | |
264 | choose_enc(Enc *enc, char *client, char *server) | |
265 | { | |
266 | char *name = match_list(client, server, NULL); | |
267 | if (name == NULL) | |
fa0f0f45 | 268 | fatal("no matching cipher found: client %s server %s", |
269 | client, server); | |
e9702f7d | 270 | if ((enc->cipher = cipher_by_name(name)) == NULL) |
3c0ef626 | 271 | fatal("matching cipher is not supported: %s", name); |
272 | enc->name = name; | |
273 | enc->enabled = 0; | |
274 | enc->iv = NULL; | |
275 | enc->key = NULL; | |
e9702f7d | 276 | enc->key_len = cipher_keylen(enc->cipher); |
277 | enc->block_size = cipher_blocksize(enc->cipher); | |
3c0ef626 | 278 | } |
30460aeb | 279 | |
3c0ef626 | 280 | static void |
281 | choose_mac(Mac *mac, char *client, char *server) | |
282 | { | |
283 | char *name = match_list(client, server, NULL); | |
284 | if (name == NULL) | |
fa0f0f45 | 285 | fatal("no matching mac found: client %s server %s", |
286 | client, server); | |
287 | if (mac_setup(mac, name) < 0) | |
3c0ef626 | 288 | fatal("unsupported mac %s", name); |
289 | /* truncate the key */ | |
290 | if (datafellows & SSH_BUG_HMAC) | |
291 | mac->key_len = 16; | |
292 | mac->name = name; | |
293 | mac->key = NULL; | |
294 | mac->enabled = 0; | |
295 | } | |
30460aeb | 296 | |
3c0ef626 | 297 | static void |
298 | choose_comp(Comp *comp, char *client, char *server) | |
299 | { | |
300 | char *name = match_list(client, server, NULL); | |
301 | if (name == NULL) | |
302 | fatal("no matching comp found: client %s server %s", client, server); | |
2ce0bfe4 | 303 | if (strcmp(name, "zlib@openssh.com") == 0) { |
304 | comp->type = COMP_DELAYED; | |
305 | } else if (strcmp(name, "zlib") == 0) { | |
306 | comp->type = COMP_ZLIB; | |
3c0ef626 | 307 | } else if (strcmp(name, "none") == 0) { |
2ce0bfe4 | 308 | comp->type = COMP_NONE; |
3c0ef626 | 309 | } else { |
310 | fatal("unsupported comp %s", name); | |
311 | } | |
312 | comp->name = name; | |
313 | } | |
30460aeb | 314 | |
3c0ef626 | 315 | static void |
316 | choose_kex(Kex *k, char *client, char *server) | |
317 | { | |
318 | k->name = match_list(client, server, NULL); | |
319 | if (k->name == NULL) | |
fa0f0f45 | 320 | fatal("Unable to negotiate a key exchange method"); |
3c0ef626 | 321 | if (strcmp(k->name, KEX_DH1) == 0) { |
8afc6a66 | 322 | k->kex_type = KEX_DH_GRP1_SHA1; |
08822d99 | 323 | k->evp_md = EVP_sha1(); |
7e82606e | 324 | } else if (strcmp(k->name, KEX_DH14) == 0) { |
325 | k->kex_type = KEX_DH_GRP14_SHA1; | |
08822d99 | 326 | k->evp_md = EVP_sha1(); |
327 | } else if (strcmp(k->name, KEX_DHGEX_SHA1) == 0) { | |
8afc6a66 | 328 | k->kex_type = KEX_DH_GEX_SHA1; |
08822d99 | 329 | k->evp_md = EVP_sha1(); |
f713db99 | 330 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L |
331 | } else if (strcmp(k->name, KEX_DHGEX_SHA256) == 0) { | |
332 | k->kex_type = KEX_DH_GEX_SHA256; | |
333 | k->evp_md = evp_ssh_sha256(); | |
334 | #endif | |
5598e598 | 335 | #ifdef GSSAPI |
fe4ad273 | 336 | } else if (strncmp(k->name, KEX_GSS_GEX_SHA1_ID, |
f713db99 | 337 | sizeof(KEX_GSS_GEX_SHA1_ID) - 1) == 0) { |
fe4ad273 | 338 | k->kex_type = KEX_GSS_GEX_SHA1; |
08822d99 | 339 | k->evp_md = EVP_sha1(); |
c06c9ae8 | 340 | } else if (strncmp(k->name, KEX_GSS_GRP1_SHA1_ID, |
f713db99 | 341 | sizeof(KEX_GSS_GRP1_SHA1_ID) - 1) == 0) { |
8afc6a66 | 342 | k->kex_type = KEX_GSS_GRP1_SHA1; |
08822d99 | 343 | k->evp_md = EVP_sha1(); |
f713db99 | 344 | } else if (strncmp(k->name, KEX_GSS_GRP14_SHA1_ID, |
345 | sizeof(KEX_GSS_GRP14_SHA1_ID) - 1) == 0) { | |
346 | k->kex_type = KEX_GSS_GRP14_SHA1; | |
347 | k->evp_md = EVP_sha1(); | |
5598e598 | 348 | #endif |
3c0ef626 | 349 | } else |
350 | fatal("bad kex alg %s", k->name); | |
351 | } | |
08822d99 | 352 | |
3c0ef626 | 353 | static void |
354 | choose_hostkeyalg(Kex *k, char *client, char *server) | |
355 | { | |
356 | char *hostkeyalg = match_list(client, server, NULL); | |
357 | if (hostkeyalg == NULL) | |
358 | fatal("no hostkey alg"); | |
359 | k->hostkey_type = key_type_from_name(hostkeyalg); | |
360 | if (k->hostkey_type == KEY_UNSPEC) | |
361 | fatal("bad hostkey alg '%s'", hostkeyalg); | |
362 | xfree(hostkeyalg); | |
363 | } | |
364 | ||
540d72c3 | 365 | static int |
8afc6a66 | 366 | proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) |
367 | { | |
368 | static int check[] = { | |
369 | PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 | |
370 | }; | |
371 | int *idx; | |
372 | char *p; | |
373 | ||
374 | for (idx = &check[0]; *idx != -1; idx++) { | |
375 | if ((p = strchr(my[*idx], ',')) != NULL) | |
376 | *p = '\0'; | |
377 | if ((p = strchr(peer[*idx], ',')) != NULL) | |
378 | *p = '\0'; | |
379 | if (strcmp(my[*idx], peer[*idx]) != 0) { | |
380 | debug2("proposal mismatch: my %s peer %s", | |
381 | my[*idx], peer[*idx]); | |
382 | return (0); | |
383 | } | |
384 | } | |
385 | debug2("proposals match"); | |
386 | return (1); | |
387 | } | |
388 | ||
3c0ef626 | 389 | static void |
390 | kex_choose_conf(Kex *kex) | |
391 | { | |
392 | Newkeys *newkeys; | |
393 | char **my, **peer; | |
394 | char **cprop, **sprop; | |
395 | int nenc, nmac, ncomp; | |
2ce0bfe4 | 396 | u_int mode, ctos, need; |
8afc6a66 | 397 | int first_kex_follows, type; |
3c0ef626 | 398 | |
6df46d40 | 399 | int auth_flag; |
400 | ||
401 | auth_flag = packet_authentication_state(); | |
402 | ||
403 | debug ("AUTH STATE IS %d", auth_flag); | |
404 | ||
8afc6a66 | 405 | my = kex_buf2prop(&kex->my, NULL); |
406 | peer = kex_buf2prop(&kex->peer, &first_kex_follows); | |
3c0ef626 | 407 | |
408 | if (kex->server) { | |
409 | cprop=peer; | |
410 | sprop=my; | |
411 | } else { | |
412 | cprop=my; | |
413 | sprop=peer; | |
414 | } | |
415 | ||
416 | /* Algorithm Negotiation */ | |
417 | for (mode = 0; mode < MODE_MAX; mode++) { | |
30460aeb | 418 | newkeys = xcalloc(1, sizeof(*newkeys)); |
3c0ef626 | 419 | kex->newkeys[mode] = newkeys; |
fa0f0f45 | 420 | ctos = (!kex->server && mode == MODE_OUT) || |
421 | (kex->server && mode == MODE_IN); | |
3c0ef626 | 422 | nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; |
423 | nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; | |
424 | ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; | |
425 | choose_enc (&newkeys->enc, cprop[nenc], sprop[nenc]); | |
426 | choose_mac (&newkeys->mac, cprop[nmac], sprop[nmac]); | |
427 | choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); | |
6df46d40 | 428 | debug("REQUESTED ENC.NAME is '%s'", newkeys->enc.name); |
429 | if (strcmp(newkeys->enc.name, "none") == 0) { | |
430 | debug("Requesting NONE. Authflag is %d", auth_flag); | |
431 | if (auth_flag == 1) { | |
432 | debug("None requested post authentication."); | |
433 | } else { | |
434 | fatal("Pre-authentication none cipher requests are not allowed."); | |
435 | } | |
436 | } | |
3c0ef626 | 437 | debug("kex: %s %s %s %s", |
438 | ctos ? "client->server" : "server->client", | |
439 | newkeys->enc.name, | |
440 | newkeys->mac.name, | |
441 | newkeys->comp.name); | |
442 | } | |
443 | choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); | |
444 | choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], | |
445 | sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); | |
446 | need = 0; | |
447 | for (mode = 0; mode < MODE_MAX; mode++) { | |
448 | newkeys = kex->newkeys[mode]; | |
e9702f7d | 449 | if (need < newkeys->enc.key_len) |
450 | need = newkeys->enc.key_len; | |
451 | if (need < newkeys->enc.block_size) | |
452 | need = newkeys->enc.block_size; | |
3c0ef626 | 453 | if (need < newkeys->mac.key_len) |
454 | need = newkeys->mac.key_len; | |
455 | } | |
456 | /* XXX need runden? */ | |
457 | kex->we_need = need; | |
458 | ||
8afc6a66 | 459 | /* ignore the next message if the proposals do not match */ |
540d72c3 | 460 | if (first_kex_follows && !proposals_match(my, peer) && |
2ce0bfe4 | 461 | !(datafellows & SSH_BUG_FIRSTKEX)) { |
8afc6a66 | 462 | type = packet_read(); |
463 | debug2("skipping next packet (type %u)", type); | |
464 | } | |
465 | ||
3c0ef626 | 466 | kex_prop_free(my); |
467 | kex_prop_free(peer); | |
468 | } | |
469 | ||
470 | static u_char * | |
08822d99 | 471 | derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, |
472 | BIGNUM *shared_secret) | |
3c0ef626 | 473 | { |
474 | Buffer b; | |
3c0ef626 | 475 | EVP_MD_CTX md; |
476 | char c = id; | |
2ce0bfe4 | 477 | u_int have; |
08822d99 | 478 | int mdsz; |
2ce0bfe4 | 479 | u_char *digest; |
480 | ||
08822d99 | 481 | if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0) |
482 | fatal("bad kex md size %d", mdsz); | |
30460aeb | 483 | digest = xmalloc(roundup(need, mdsz)); |
3c0ef626 | 484 | |
485 | buffer_init(&b); | |
486 | buffer_put_bignum2(&b, shared_secret); | |
487 | ||
488 | /* K1 = HASH(K || H || "A" || session_id) */ | |
08822d99 | 489 | EVP_DigestInit(&md, kex->evp_md); |
3c0ef626 | 490 | if (!(datafellows & SSH_BUG_DERIVEKEY)) |
491 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
08822d99 | 492 | EVP_DigestUpdate(&md, hash, hashlen); |
3c0ef626 | 493 | EVP_DigestUpdate(&md, &c, 1); |
494 | EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len); | |
495 | EVP_DigestFinal(&md, digest, NULL); | |
496 | ||
497 | /* | |
498 | * expand key: | |
499 | * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) | |
500 | * Key = K1 || K2 || ... || Kn | |
501 | */ | |
502 | for (have = mdsz; need > have; have += mdsz) { | |
08822d99 | 503 | EVP_DigestInit(&md, kex->evp_md); |
3c0ef626 | 504 | if (!(datafellows & SSH_BUG_DERIVEKEY)) |
505 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
08822d99 | 506 | EVP_DigestUpdate(&md, hash, hashlen); |
3c0ef626 | 507 | EVP_DigestUpdate(&md, digest, have); |
508 | EVP_DigestFinal(&md, digest + have, NULL); | |
509 | } | |
510 | buffer_free(&b); | |
511 | #ifdef DEBUG_KEX | |
512 | fprintf(stderr, "key '%c'== ", c); | |
513 | dump_digest("key", digest, need); | |
514 | #endif | |
515 | return digest; | |
516 | } | |
517 | ||
518 | Newkeys *current_keys[MODE_MAX]; | |
519 | ||
520 | #define NKEYS 6 | |
521 | void | |
08822d99 | 522 | kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret) |
3c0ef626 | 523 | { |
524 | u_char *keys[NKEYS]; | |
2ce0bfe4 | 525 | u_int i, mode, ctos; |
3c0ef626 | 526 | |
08822d99 | 527 | for (i = 0; i < NKEYS; i++) { |
528 | keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, | |
529 | shared_secret); | |
530 | } | |
3c0ef626 | 531 | |
8afc6a66 | 532 | debug2("kex_derive_keys"); |
3c0ef626 | 533 | for (mode = 0; mode < MODE_MAX; mode++) { |
534 | current_keys[mode] = kex->newkeys[mode]; | |
535 | kex->newkeys[mode] = NULL; | |
30460aeb | 536 | ctos = (!kex->server && mode == MODE_OUT) || |
537 | (kex->server && mode == MODE_IN); | |
3c0ef626 | 538 | current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; |
539 | current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; | |
540 | current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; | |
541 | } | |
542 | } | |
543 | ||
544 | Newkeys * | |
545 | kex_get_newkeys(int mode) | |
546 | { | |
547 | Newkeys *ret; | |
548 | ||
549 | ret = current_keys[mode]; | |
550 | current_keys[mode] = NULL; | |
551 | return ret; | |
552 | } | |
553 | ||
7e82606e | 554 | void |
555 | derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, | |
556 | u_int8_t cookie[8], u_int8_t id[16]) | |
557 | { | |
558 | const EVP_MD *evp_md = EVP_md5(); | |
559 | EVP_MD_CTX md; | |
560 | u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE]; | |
561 | int len; | |
562 | ||
563 | EVP_DigestInit(&md, evp_md); | |
564 | ||
565 | len = BN_num_bytes(host_modulus); | |
2ce0bfe4 | 566 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) |
7e82606e | 567 | fatal("%s: bad host modulus (len %d)", __func__, len); |
568 | BN_bn2bin(host_modulus, nbuf); | |
569 | EVP_DigestUpdate(&md, nbuf, len); | |
570 | ||
571 | len = BN_num_bytes(server_modulus); | |
2ce0bfe4 | 572 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) |
7e82606e | 573 | fatal("%s: bad server modulus (len %d)", __func__, len); |
574 | BN_bn2bin(server_modulus, nbuf); | |
575 | EVP_DigestUpdate(&md, nbuf, len); | |
576 | ||
577 | EVP_DigestUpdate(&md, cookie, 8); | |
578 | ||
579 | EVP_DigestFinal(&md, obuf, NULL); | |
580 | memcpy(id, obuf, 16); | |
581 | ||
582 | memset(nbuf, 0, sizeof(nbuf)); | |
583 | memset(obuf, 0, sizeof(obuf)); | |
584 | memset(&md, 0, sizeof(md)); | |
585 | } | |
586 | ||
3c0ef626 | 587 | #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) |
588 | void | |
589 | dump_digest(char *msg, u_char *digest, int len) | |
590 | { | |
2ce0bfe4 | 591 | u_int i; |
3c0ef626 | 592 | |
593 | fprintf(stderr, "%s\n", msg); | |
0b90ac93 | 594 | for (i = 0; i < len; i++) { |
3c0ef626 | 595 | fprintf(stderr, "%02x", digest[i]); |
596 | if (i%32 == 31) | |
597 | fprintf(stderr, "\n"); | |
598 | else if (i%8 == 7) | |
599 | fprintf(stderr, " "); | |
600 | } | |
601 | fprintf(stderr, "\n"); | |
602 | } | |
603 | #endif |