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b5afdff5 | 1 | /* $OpenBSD: kex.c,v 1.81 2009/05/27 06:34:36 andreas 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" |
fa7499cc | 51 | #include "canohost.h" |
3c0ef626 | 52 | |
5598e598 | 53 | #ifdef GSSAPI |
54 | #include "ssh-gss.h" | |
55 | #endif | |
56 | ||
30460aeb | 57 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L |
58 | # if defined(HAVE_EVP_SHA256) | |
59 | # define evp_ssh_sha256 EVP_sha256 | |
60 | # else | |
61 | extern const EVP_MD *evp_ssh_sha256(void); | |
62 | # endif | |
63 | #endif | |
64 | ||
3c0ef626 | 65 | /* prototype */ |
66 | static void kex_kexinit_finish(Kex *); | |
67 | static void kex_choose_conf(Kex *); | |
68 | ||
69 | /* put algorithm proposal into buffer */ | |
6df46d40 | 70 | /* used in sshconnect.c as well as kex.c */ |
473db5ab | 71 | void |
3c0ef626 | 72 | kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) |
73 | { | |
2ce0bfe4 | 74 | u_int i; |
3c0ef626 | 75 | |
76 | buffer_clear(b); | |
350391c5 | 77 | /* |
78 | * add a dummy cookie, the cookie will be overwritten by | |
79 | * kex_send_kexinit(), each time a kexinit is set | |
80 | */ | |
81 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
82 | buffer_put_char(b, 0); | |
3c0ef626 | 83 | for (i = 0; i < PROPOSAL_MAX; i++) |
84 | buffer_put_cstring(b, proposal[i]); | |
85 | buffer_put_char(b, 0); /* first_kex_packet_follows */ | |
86 | buffer_put_int(b, 0); /* uint32 reserved */ | |
87 | } | |
88 | ||
89 | /* parse buffer and return algorithm proposal */ | |
90 | static char ** | |
8afc6a66 | 91 | kex_buf2prop(Buffer *raw, int *first_kex_follows) |
3c0ef626 | 92 | { |
93 | Buffer b; | |
fa0f0f45 | 94 | u_int i; |
3c0ef626 | 95 | char **proposal; |
96 | ||
30460aeb | 97 | proposal = xcalloc(PROPOSAL_MAX, sizeof(char *)); |
3c0ef626 | 98 | |
99 | buffer_init(&b); | |
100 | buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); | |
101 | /* skip cookie */ | |
102 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
103 | buffer_get_char(&b); | |
104 | /* extract kex init proposal strings */ | |
105 | for (i = 0; i < PROPOSAL_MAX; i++) { | |
106 | proposal[i] = buffer_get_string(&b,NULL); | |
107 | debug2("kex_parse_kexinit: %s", proposal[i]); | |
108 | } | |
109 | /* first kex follows / reserved */ | |
110 | i = buffer_get_char(&b); | |
8afc6a66 | 111 | if (first_kex_follows != NULL) |
112 | *first_kex_follows = i; | |
3c0ef626 | 113 | debug2("kex_parse_kexinit: first_kex_follows %d ", i); |
114 | i = buffer_get_int(&b); | |
fa0f0f45 | 115 | debug2("kex_parse_kexinit: reserved %u ", i); |
3c0ef626 | 116 | buffer_free(&b); |
117 | return proposal; | |
118 | } | |
119 | ||
120 | static void | |
121 | kex_prop_free(char **proposal) | |
122 | { | |
2ce0bfe4 | 123 | u_int i; |
3c0ef626 | 124 | |
125 | for (i = 0; i < PROPOSAL_MAX; i++) | |
126 | xfree(proposal[i]); | |
127 | xfree(proposal); | |
128 | } | |
129 | ||
fa0f0f45 | 130 | /* ARGSUSED */ |
3c0ef626 | 131 | static void |
e9702f7d | 132 | kex_protocol_error(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 133 | { |
e9702f7d | 134 | error("Hm, kex protocol error: type %d seq %u", type, seq); |
3c0ef626 | 135 | } |
136 | ||
137 | static void | |
e9702f7d | 138 | kex_reset_dispatch(void) |
3c0ef626 | 139 | { |
e9702f7d | 140 | dispatch_range(SSH2_MSG_TRANSPORT_MIN, |
141 | SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); | |
142 | dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); | |
3c0ef626 | 143 | } |
144 | ||
145 | void | |
146 | kex_finish(Kex *kex) | |
147 | { | |
e9702f7d | 148 | kex_reset_dispatch(); |
3c0ef626 | 149 | |
150 | packet_start(SSH2_MSG_NEWKEYS); | |
151 | packet_send(); | |
152 | /* packet_write_wait(); */ | |
153 | debug("SSH2_MSG_NEWKEYS sent"); | |
154 | ||
8afc6a66 | 155 | debug("expecting SSH2_MSG_NEWKEYS"); |
e9702f7d | 156 | packet_read_expect(SSH2_MSG_NEWKEYS); |
157 | packet_check_eom(); | |
3c0ef626 | 158 | debug("SSH2_MSG_NEWKEYS received"); |
159 | ||
160 | kex->done = 1; | |
161 | buffer_clear(&kex->peer); | |
162 | /* buffer_clear(&kex->my); */ | |
163 | kex->flags &= ~KEX_INIT_SENT; | |
164 | xfree(kex->name); | |
165 | kex->name = NULL; | |
166 | } | |
167 | ||
168 | void | |
169 | kex_send_kexinit(Kex *kex) | |
170 | { | |
7e82606e | 171 | u_int32_t rnd = 0; |
350391c5 | 172 | u_char *cookie; |
2ce0bfe4 | 173 | u_int i; |
350391c5 | 174 | |
3c0ef626 | 175 | if (kex == NULL) { |
176 | error("kex_send_kexinit: no kex, cannot rekey"); | |
177 | return; | |
178 | } | |
179 | if (kex->flags & KEX_INIT_SENT) { | |
180 | debug("KEX_INIT_SENT"); | |
181 | return; | |
182 | } | |
183 | kex->done = 0; | |
350391c5 | 184 | |
185 | /* generate a random cookie */ | |
186 | if (buffer_len(&kex->my) < KEX_COOKIE_LEN) | |
187 | fatal("kex_send_kexinit: kex proposal too short"); | |
188 | cookie = buffer_ptr(&kex->my); | |
189 | for (i = 0; i < KEX_COOKIE_LEN; i++) { | |
190 | if (i % 4 == 0) | |
7e82606e | 191 | rnd = arc4random(); |
192 | cookie[i] = rnd; | |
193 | rnd >>= 8; | |
350391c5 | 194 | } |
3c0ef626 | 195 | packet_start(SSH2_MSG_KEXINIT); |
196 | packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); | |
197 | packet_send(); | |
198 | debug("SSH2_MSG_KEXINIT sent"); | |
199 | kex->flags |= KEX_INIT_SENT; | |
200 | } | |
201 | ||
fa0f0f45 | 202 | /* ARGSUSED */ |
3c0ef626 | 203 | void |
e9702f7d | 204 | kex_input_kexinit(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 205 | { |
206 | char *ptr; | |
2ce0bfe4 | 207 | u_int i, dlen; |
3c0ef626 | 208 | Kex *kex = (Kex *)ctxt; |
209 | ||
210 | debug("SSH2_MSG_KEXINIT received"); | |
211 | if (kex == NULL) | |
212 | fatal("kex_input_kexinit: no kex, cannot rekey"); | |
213 | ||
214 | ptr = packet_get_raw(&dlen); | |
215 | buffer_append(&kex->peer, ptr, dlen); | |
216 | ||
217 | /* discard packet */ | |
218 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
219 | packet_get_char(); | |
220 | for (i = 0; i < PROPOSAL_MAX; i++) | |
221 | xfree(packet_get_string(NULL)); | |
276b07a3 | 222 | (void) packet_get_char(); |
223 | (void) packet_get_int(); | |
e9702f7d | 224 | packet_check_eom(); |
3c0ef626 | 225 | |
226 | kex_kexinit_finish(kex); | |
227 | } | |
228 | ||
229 | Kex * | |
230 | kex_setup(char *proposal[PROPOSAL_MAX]) | |
231 | { | |
232 | Kex *kex; | |
233 | ||
30460aeb | 234 | kex = xcalloc(1, sizeof(*kex)); |
3c0ef626 | 235 | buffer_init(&kex->peer); |
236 | buffer_init(&kex->my); | |
237 | kex_prop2buf(&kex->my, proposal); | |
238 | kex->done = 0; | |
239 | ||
240 | kex_send_kexinit(kex); /* we start */ | |
e9702f7d | 241 | kex_reset_dispatch(); |
3c0ef626 | 242 | |
243 | return kex; | |
244 | } | |
245 | ||
246 | static void | |
247 | kex_kexinit_finish(Kex *kex) | |
248 | { | |
249 | if (!(kex->flags & KEX_INIT_SENT)) | |
250 | kex_send_kexinit(kex); | |
251 | ||
252 | kex_choose_conf(kex); | |
253 | ||
8afc6a66 | 254 | if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX && |
255 | kex->kex[kex->kex_type] != NULL) { | |
256 | (kex->kex[kex->kex_type])(kex); | |
257 | } else { | |
3c0ef626 | 258 | fatal("Unsupported key exchange %d", kex->kex_type); |
259 | } | |
260 | } | |
261 | ||
262 | static void | |
263 | choose_enc(Enc *enc, char *client, char *server) | |
264 | { | |
265 | char *name = match_list(client, server, NULL); | |
266 | if (name == NULL) | |
fa0f0f45 | 267 | fatal("no matching cipher found: client %s server %s", |
268 | client, server); | |
e9702f7d | 269 | if ((enc->cipher = cipher_by_name(name)) == NULL) |
3c0ef626 | 270 | fatal("matching cipher is not supported: %s", name); |
271 | enc->name = name; | |
272 | enc->enabled = 0; | |
273 | enc->iv = NULL; | |
274 | enc->key = NULL; | |
e9702f7d | 275 | enc->key_len = cipher_keylen(enc->cipher); |
276 | enc->block_size = cipher_blocksize(enc->cipher); | |
3c0ef626 | 277 | } |
30460aeb | 278 | |
3c0ef626 | 279 | static void |
280 | choose_mac(Mac *mac, char *client, char *server) | |
281 | { | |
282 | char *name = match_list(client, server, NULL); | |
283 | if (name == NULL) | |
fa0f0f45 | 284 | fatal("no matching mac found: client %s server %s", |
285 | client, server); | |
286 | if (mac_setup(mac, name) < 0) | |
3c0ef626 | 287 | fatal("unsupported mac %s", name); |
288 | /* truncate the key */ | |
289 | if (datafellows & SSH_BUG_HMAC) | |
290 | mac->key_len = 16; | |
291 | mac->name = name; | |
292 | mac->key = NULL; | |
293 | mac->enabled = 0; | |
294 | } | |
30460aeb | 295 | |
3c0ef626 | 296 | static void |
297 | choose_comp(Comp *comp, char *client, char *server) | |
298 | { | |
299 | char *name = match_list(client, server, NULL); | |
300 | if (name == NULL) | |
301 | fatal("no matching comp found: client %s server %s", client, server); | |
2ce0bfe4 | 302 | if (strcmp(name, "zlib@openssh.com") == 0) { |
303 | comp->type = COMP_DELAYED; | |
304 | } else if (strcmp(name, "zlib") == 0) { | |
305 | comp->type = COMP_ZLIB; | |
3c0ef626 | 306 | } else if (strcmp(name, "none") == 0) { |
2ce0bfe4 | 307 | comp->type = COMP_NONE; |
3c0ef626 | 308 | } else { |
309 | fatal("unsupported comp %s", name); | |
310 | } | |
311 | comp->name = name; | |
312 | } | |
30460aeb | 313 | |
3c0ef626 | 314 | static void |
315 | choose_kex(Kex *k, char *client, char *server) | |
316 | { | |
317 | k->name = match_list(client, server, NULL); | |
318 | if (k->name == NULL) | |
fa0f0f45 | 319 | fatal("Unable to negotiate a key exchange method"); |
3c0ef626 | 320 | if (strcmp(k->name, KEX_DH1) == 0) { |
8afc6a66 | 321 | k->kex_type = KEX_DH_GRP1_SHA1; |
08822d99 | 322 | k->evp_md = EVP_sha1(); |
7e82606e | 323 | } else if (strcmp(k->name, KEX_DH14) == 0) { |
324 | k->kex_type = KEX_DH_GRP14_SHA1; | |
08822d99 | 325 | k->evp_md = EVP_sha1(); |
326 | } else if (strcmp(k->name, KEX_DHGEX_SHA1) == 0) { | |
8afc6a66 | 327 | k->kex_type = KEX_DH_GEX_SHA1; |
08822d99 | 328 | k->evp_md = EVP_sha1(); |
f713db99 | 329 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L |
330 | } else if (strcmp(k->name, KEX_DHGEX_SHA256) == 0) { | |
331 | k->kex_type = KEX_DH_GEX_SHA256; | |
332 | k->evp_md = evp_ssh_sha256(); | |
333 | #endif | |
5598e598 | 334 | #ifdef GSSAPI |
fe4ad273 | 335 | } else if (strncmp(k->name, KEX_GSS_GEX_SHA1_ID, |
f713db99 | 336 | sizeof(KEX_GSS_GEX_SHA1_ID) - 1) == 0) { |
fe4ad273 | 337 | k->kex_type = KEX_GSS_GEX_SHA1; |
08822d99 | 338 | k->evp_md = EVP_sha1(); |
c06c9ae8 | 339 | } else if (strncmp(k->name, KEX_GSS_GRP1_SHA1_ID, |
f713db99 | 340 | sizeof(KEX_GSS_GRP1_SHA1_ID) - 1) == 0) { |
8afc6a66 | 341 | k->kex_type = KEX_GSS_GRP1_SHA1; |
08822d99 | 342 | k->evp_md = EVP_sha1(); |
f713db99 | 343 | } else if (strncmp(k->name, KEX_GSS_GRP14_SHA1_ID, |
344 | sizeof(KEX_GSS_GRP14_SHA1_ID) - 1) == 0) { | |
345 | k->kex_type = KEX_GSS_GRP14_SHA1; | |
346 | k->evp_md = EVP_sha1(); | |
5598e598 | 347 | #endif |
3c0ef626 | 348 | } else |
349 | fatal("bad kex alg %s", k->name); | |
350 | } | |
08822d99 | 351 | |
3c0ef626 | 352 | static void |
353 | choose_hostkeyalg(Kex *k, char *client, char *server) | |
354 | { | |
355 | char *hostkeyalg = match_list(client, server, NULL); | |
356 | if (hostkeyalg == NULL) | |
357 | fatal("no hostkey alg"); | |
358 | k->hostkey_type = key_type_from_name(hostkeyalg); | |
359 | if (k->hostkey_type == KEY_UNSPEC) | |
360 | fatal("bad hostkey alg '%s'", hostkeyalg); | |
361 | xfree(hostkeyalg); | |
362 | } | |
363 | ||
540d72c3 | 364 | static int |
8afc6a66 | 365 | proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) |
366 | { | |
367 | static int check[] = { | |
368 | PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 | |
369 | }; | |
370 | int *idx; | |
371 | char *p; | |
372 | ||
373 | for (idx = &check[0]; *idx != -1; idx++) { | |
374 | if ((p = strchr(my[*idx], ',')) != NULL) | |
375 | *p = '\0'; | |
376 | if ((p = strchr(peer[*idx], ',')) != NULL) | |
377 | *p = '\0'; | |
378 | if (strcmp(my[*idx], peer[*idx]) != 0) { | |
379 | debug2("proposal mismatch: my %s peer %s", | |
380 | my[*idx], peer[*idx]); | |
381 | return (0); | |
382 | } | |
383 | } | |
384 | debug2("proposals match"); | |
385 | return (1); | |
386 | } | |
387 | ||
3c0ef626 | 388 | static void |
389 | kex_choose_conf(Kex *kex) | |
390 | { | |
391 | Newkeys *newkeys; | |
392 | char **my, **peer; | |
393 | char **cprop, **sprop; | |
394 | int nenc, nmac, ncomp; | |
2ce0bfe4 | 395 | u_int mode, ctos, need; |
8afc6a66 | 396 | int first_kex_follows, type; |
fa7499cc | 397 | int log_flag = 0; |
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); | |
fa7499cc | 442 | /* client starts withctos = 0 && log flag = 0 and no log*/ |
443 | /* 2nd client pass ctos=1 and flag = 1 so no log*/ | |
444 | /* server starts with ctos =1 && log_flag = 0 so log */ | |
445 | /* 2nd sever pass ctos = 1 && log flag = 1 so no log*/ | |
446 | /* -cjr*/ | |
447 | if (ctos && !log_flag) { | |
448 | logit("SSH: Server;Ltype: Kex;Remote: %s-%d;Enc: %s;MAC: %s;Comp: %s", | |
449 | get_remote_ipaddr(), | |
450 | get_remote_port(), | |
451 | newkeys->enc.name, | |
452 | newkeys->mac.name, | |
453 | newkeys->comp.name); | |
454 | } | |
455 | log_flag = 1; | |
3c0ef626 | 456 | } |
457 | choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); | |
458 | choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], | |
459 | sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); | |
460 | need = 0; | |
461 | for (mode = 0; mode < MODE_MAX; mode++) { | |
462 | newkeys = kex->newkeys[mode]; | |
e9702f7d | 463 | if (need < newkeys->enc.key_len) |
464 | need = newkeys->enc.key_len; | |
465 | if (need < newkeys->enc.block_size) | |
466 | need = newkeys->enc.block_size; | |
3c0ef626 | 467 | if (need < newkeys->mac.key_len) |
468 | need = newkeys->mac.key_len; | |
469 | } | |
470 | /* XXX need runden? */ | |
471 | kex->we_need = need; | |
472 | ||
8afc6a66 | 473 | /* ignore the next message if the proposals do not match */ |
540d72c3 | 474 | if (first_kex_follows && !proposals_match(my, peer) && |
2ce0bfe4 | 475 | !(datafellows & SSH_BUG_FIRSTKEX)) { |
8afc6a66 | 476 | type = packet_read(); |
477 | debug2("skipping next packet (type %u)", type); | |
478 | } | |
479 | ||
3c0ef626 | 480 | kex_prop_free(my); |
481 | kex_prop_free(peer); | |
482 | } | |
483 | ||
484 | static u_char * | |
08822d99 | 485 | derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, |
486 | BIGNUM *shared_secret) | |
3c0ef626 | 487 | { |
488 | Buffer b; | |
3c0ef626 | 489 | EVP_MD_CTX md; |
490 | char c = id; | |
2ce0bfe4 | 491 | u_int have; |
08822d99 | 492 | int mdsz; |
2ce0bfe4 | 493 | u_char *digest; |
494 | ||
08822d99 | 495 | if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0) |
496 | fatal("bad kex md size %d", mdsz); | |
30460aeb | 497 | digest = xmalloc(roundup(need, mdsz)); |
3c0ef626 | 498 | |
499 | buffer_init(&b); | |
500 | buffer_put_bignum2(&b, shared_secret); | |
501 | ||
502 | /* K1 = HASH(K || H || "A" || session_id) */ | |
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, &c, 1); |
508 | EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len); | |
509 | EVP_DigestFinal(&md, digest, NULL); | |
510 | ||
511 | /* | |
512 | * expand key: | |
513 | * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) | |
514 | * Key = K1 || K2 || ... || Kn | |
515 | */ | |
516 | for (have = mdsz; need > have; have += mdsz) { | |
08822d99 | 517 | EVP_DigestInit(&md, kex->evp_md); |
3c0ef626 | 518 | if (!(datafellows & SSH_BUG_DERIVEKEY)) |
519 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
08822d99 | 520 | EVP_DigestUpdate(&md, hash, hashlen); |
3c0ef626 | 521 | EVP_DigestUpdate(&md, digest, have); |
522 | EVP_DigestFinal(&md, digest + have, NULL); | |
523 | } | |
524 | buffer_free(&b); | |
525 | #ifdef DEBUG_KEX | |
526 | fprintf(stderr, "key '%c'== ", c); | |
527 | dump_digest("key", digest, need); | |
528 | #endif | |
529 | return digest; | |
530 | } | |
531 | ||
532 | Newkeys *current_keys[MODE_MAX]; | |
533 | ||
534 | #define NKEYS 6 | |
535 | void | |
08822d99 | 536 | kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret) |
3c0ef626 | 537 | { |
538 | u_char *keys[NKEYS]; | |
2ce0bfe4 | 539 | u_int i, mode, ctos; |
3c0ef626 | 540 | |
08822d99 | 541 | for (i = 0; i < NKEYS; i++) { |
542 | keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, | |
543 | shared_secret); | |
544 | } | |
3c0ef626 | 545 | |
8afc6a66 | 546 | debug2("kex_derive_keys"); |
3c0ef626 | 547 | for (mode = 0; mode < MODE_MAX; mode++) { |
548 | current_keys[mode] = kex->newkeys[mode]; | |
549 | kex->newkeys[mode] = NULL; | |
30460aeb | 550 | ctos = (!kex->server && mode == MODE_OUT) || |
551 | (kex->server && mode == MODE_IN); | |
3c0ef626 | 552 | current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; |
553 | current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; | |
554 | current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; | |
555 | } | |
556 | } | |
557 | ||
558 | Newkeys * | |
559 | kex_get_newkeys(int mode) | |
560 | { | |
561 | Newkeys *ret; | |
562 | ||
563 | ret = current_keys[mode]; | |
564 | current_keys[mode] = NULL; | |
565 | return ret; | |
566 | } | |
567 | ||
7e82606e | 568 | void |
569 | derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, | |
570 | u_int8_t cookie[8], u_int8_t id[16]) | |
571 | { | |
572 | const EVP_MD *evp_md = EVP_md5(); | |
573 | EVP_MD_CTX md; | |
574 | u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE]; | |
575 | int len; | |
576 | ||
577 | EVP_DigestInit(&md, evp_md); | |
578 | ||
579 | len = BN_num_bytes(host_modulus); | |
2ce0bfe4 | 580 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) |
7e82606e | 581 | fatal("%s: bad host modulus (len %d)", __func__, len); |
582 | BN_bn2bin(host_modulus, nbuf); | |
583 | EVP_DigestUpdate(&md, nbuf, len); | |
584 | ||
585 | len = BN_num_bytes(server_modulus); | |
2ce0bfe4 | 586 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) |
7e82606e | 587 | fatal("%s: bad server modulus (len %d)", __func__, len); |
588 | BN_bn2bin(server_modulus, nbuf); | |
589 | EVP_DigestUpdate(&md, nbuf, len); | |
590 | ||
591 | EVP_DigestUpdate(&md, cookie, 8); | |
592 | ||
593 | EVP_DigestFinal(&md, obuf, NULL); | |
594 | memcpy(id, obuf, 16); | |
595 | ||
596 | memset(nbuf, 0, sizeof(nbuf)); | |
597 | memset(obuf, 0, sizeof(obuf)); | |
598 | memset(&md, 0, sizeof(md)); | |
599 | } | |
600 | ||
3c0ef626 | 601 | #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) |
602 | void | |
603 | dump_digest(char *msg, u_char *digest, int len) | |
604 | { | |
2ce0bfe4 | 605 | u_int i; |
3c0ef626 | 606 | |
607 | fprintf(stderr, "%s\n", msg); | |
0b90ac93 | 608 | for (i = 0; i < len; i++) { |
3c0ef626 | 609 | fprintf(stderr, "%02x", digest[i]); |
610 | if (i%32 == 31) | |
611 | fprintf(stderr, "\n"); | |
612 | else if (i%8 == 7) | |
613 | fprintf(stderr, " "); | |
614 | } | |
615 | fprintf(stderr, "\n"); | |
616 | } | |
617 | #endif |