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5262cbfb | 1 | /* $OpenBSD: kex.c,v 1.80 2008/09/06 12:24:13 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" |
fa7499cc | 51 | #include "canohost.h" |
3c0ef626 | 52 | |
5598e598 | 53 | #ifdef GSSAPI |
54 | #include "ssh-gss.h" | |
55 | #endif | |
56 | ||
3c0ef626 | 57 | #define KEX_COOKIE_LEN 16 |
58 | ||
30460aeb | 59 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L |
60 | # if defined(HAVE_EVP_SHA256) | |
61 | # define evp_ssh_sha256 EVP_sha256 | |
62 | # else | |
63 | extern const EVP_MD *evp_ssh_sha256(void); | |
64 | # endif | |
65 | #endif | |
66 | ||
3c0ef626 | 67 | /* prototype */ |
68 | static void kex_kexinit_finish(Kex *); | |
69 | static void kex_choose_conf(Kex *); | |
70 | ||
71 | /* put algorithm proposal into buffer */ | |
6df46d40 | 72 | /* used in sshconnect.c as well as kex.c */ |
473db5ab | 73 | void |
3c0ef626 | 74 | kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) |
75 | { | |
2ce0bfe4 | 76 | u_int i; |
3c0ef626 | 77 | |
78 | buffer_clear(b); | |
350391c5 | 79 | /* |
80 | * add a dummy cookie, the cookie will be overwritten by | |
81 | * kex_send_kexinit(), each time a kexinit is set | |
82 | */ | |
83 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
84 | buffer_put_char(b, 0); | |
3c0ef626 | 85 | for (i = 0; i < PROPOSAL_MAX; i++) |
86 | buffer_put_cstring(b, proposal[i]); | |
87 | buffer_put_char(b, 0); /* first_kex_packet_follows */ | |
88 | buffer_put_int(b, 0); /* uint32 reserved */ | |
89 | } | |
90 | ||
91 | /* parse buffer and return algorithm proposal */ | |
92 | static char ** | |
8afc6a66 | 93 | kex_buf2prop(Buffer *raw, int *first_kex_follows) |
3c0ef626 | 94 | { |
95 | Buffer b; | |
fa0f0f45 | 96 | u_int i; |
3c0ef626 | 97 | char **proposal; |
98 | ||
30460aeb | 99 | proposal = xcalloc(PROPOSAL_MAX, sizeof(char *)); |
3c0ef626 | 100 | |
101 | buffer_init(&b); | |
102 | buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); | |
103 | /* skip cookie */ | |
104 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
105 | buffer_get_char(&b); | |
106 | /* extract kex init proposal strings */ | |
107 | for (i = 0; i < PROPOSAL_MAX; i++) { | |
108 | proposal[i] = buffer_get_string(&b,NULL); | |
109 | debug2("kex_parse_kexinit: %s", proposal[i]); | |
110 | } | |
111 | /* first kex follows / reserved */ | |
112 | i = buffer_get_char(&b); | |
8afc6a66 | 113 | if (first_kex_follows != NULL) |
114 | *first_kex_follows = i; | |
3c0ef626 | 115 | debug2("kex_parse_kexinit: first_kex_follows %d ", i); |
116 | i = buffer_get_int(&b); | |
fa0f0f45 | 117 | debug2("kex_parse_kexinit: reserved %u ", i); |
3c0ef626 | 118 | buffer_free(&b); |
119 | return proposal; | |
120 | } | |
121 | ||
122 | static void | |
123 | kex_prop_free(char **proposal) | |
124 | { | |
2ce0bfe4 | 125 | u_int i; |
3c0ef626 | 126 | |
127 | for (i = 0; i < PROPOSAL_MAX; i++) | |
128 | xfree(proposal[i]); | |
129 | xfree(proposal); | |
130 | } | |
131 | ||
fa0f0f45 | 132 | /* ARGSUSED */ |
3c0ef626 | 133 | static void |
e9702f7d | 134 | kex_protocol_error(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 135 | { |
e9702f7d | 136 | error("Hm, kex protocol error: type %d seq %u", type, seq); |
3c0ef626 | 137 | } |
138 | ||
139 | static void | |
e9702f7d | 140 | kex_reset_dispatch(void) |
3c0ef626 | 141 | { |
e9702f7d | 142 | dispatch_range(SSH2_MSG_TRANSPORT_MIN, |
143 | SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); | |
144 | dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); | |
3c0ef626 | 145 | } |
146 | ||
147 | void | |
148 | kex_finish(Kex *kex) | |
149 | { | |
e9702f7d | 150 | kex_reset_dispatch(); |
3c0ef626 | 151 | |
152 | packet_start(SSH2_MSG_NEWKEYS); | |
153 | packet_send(); | |
154 | /* packet_write_wait(); */ | |
155 | debug("SSH2_MSG_NEWKEYS sent"); | |
156 | ||
8afc6a66 | 157 | debug("expecting SSH2_MSG_NEWKEYS"); |
e9702f7d | 158 | packet_read_expect(SSH2_MSG_NEWKEYS); |
159 | packet_check_eom(); | |
3c0ef626 | 160 | debug("SSH2_MSG_NEWKEYS received"); |
161 | ||
162 | kex->done = 1; | |
163 | buffer_clear(&kex->peer); | |
164 | /* buffer_clear(&kex->my); */ | |
165 | kex->flags &= ~KEX_INIT_SENT; | |
166 | xfree(kex->name); | |
167 | kex->name = NULL; | |
168 | } | |
169 | ||
170 | void | |
171 | kex_send_kexinit(Kex *kex) | |
172 | { | |
7e82606e | 173 | u_int32_t rnd = 0; |
350391c5 | 174 | u_char *cookie; |
2ce0bfe4 | 175 | u_int i; |
350391c5 | 176 | |
3c0ef626 | 177 | if (kex == NULL) { |
178 | error("kex_send_kexinit: no kex, cannot rekey"); | |
179 | return; | |
180 | } | |
181 | if (kex->flags & KEX_INIT_SENT) { | |
182 | debug("KEX_INIT_SENT"); | |
183 | return; | |
184 | } | |
185 | kex->done = 0; | |
350391c5 | 186 | |
187 | /* generate a random cookie */ | |
188 | if (buffer_len(&kex->my) < KEX_COOKIE_LEN) | |
189 | fatal("kex_send_kexinit: kex proposal too short"); | |
190 | cookie = buffer_ptr(&kex->my); | |
191 | for (i = 0; i < KEX_COOKIE_LEN; i++) { | |
192 | if (i % 4 == 0) | |
7e82606e | 193 | rnd = arc4random(); |
194 | cookie[i] = rnd; | |
195 | rnd >>= 8; | |
350391c5 | 196 | } |
3c0ef626 | 197 | packet_start(SSH2_MSG_KEXINIT); |
198 | packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); | |
199 | packet_send(); | |
200 | debug("SSH2_MSG_KEXINIT sent"); | |
201 | kex->flags |= KEX_INIT_SENT; | |
202 | } | |
203 | ||
fa0f0f45 | 204 | /* ARGSUSED */ |
3c0ef626 | 205 | void |
e9702f7d | 206 | kex_input_kexinit(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 207 | { |
208 | char *ptr; | |
2ce0bfe4 | 209 | u_int i, dlen; |
3c0ef626 | 210 | Kex *kex = (Kex *)ctxt; |
211 | ||
212 | debug("SSH2_MSG_KEXINIT received"); | |
213 | if (kex == NULL) | |
214 | fatal("kex_input_kexinit: no kex, cannot rekey"); | |
215 | ||
216 | ptr = packet_get_raw(&dlen); | |
217 | buffer_append(&kex->peer, ptr, dlen); | |
218 | ||
219 | /* discard packet */ | |
220 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
221 | packet_get_char(); | |
222 | for (i = 0; i < PROPOSAL_MAX; i++) | |
223 | xfree(packet_get_string(NULL)); | |
276b07a3 | 224 | (void) packet_get_char(); |
225 | (void) packet_get_int(); | |
e9702f7d | 226 | packet_check_eom(); |
3c0ef626 | 227 | |
228 | kex_kexinit_finish(kex); | |
229 | } | |
230 | ||
231 | Kex * | |
232 | kex_setup(char *proposal[PROPOSAL_MAX]) | |
233 | { | |
234 | Kex *kex; | |
235 | ||
30460aeb | 236 | kex = xcalloc(1, sizeof(*kex)); |
3c0ef626 | 237 | buffer_init(&kex->peer); |
238 | buffer_init(&kex->my); | |
239 | kex_prop2buf(&kex->my, proposal); | |
240 | kex->done = 0; | |
241 | ||
242 | kex_send_kexinit(kex); /* we start */ | |
e9702f7d | 243 | kex_reset_dispatch(); |
3c0ef626 | 244 | |
245 | return kex; | |
246 | } | |
247 | ||
248 | static void | |
249 | kex_kexinit_finish(Kex *kex) | |
250 | { | |
251 | if (!(kex->flags & KEX_INIT_SENT)) | |
252 | kex_send_kexinit(kex); | |
253 | ||
254 | kex_choose_conf(kex); | |
255 | ||
8afc6a66 | 256 | if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX && |
257 | kex->kex[kex->kex_type] != NULL) { | |
258 | (kex->kex[kex->kex_type])(kex); | |
259 | } else { | |
3c0ef626 | 260 | fatal("Unsupported key exchange %d", kex->kex_type); |
261 | } | |
262 | } | |
263 | ||
264 | static void | |
265 | choose_enc(Enc *enc, char *client, char *server) | |
266 | { | |
267 | char *name = match_list(client, server, NULL); | |
268 | if (name == NULL) | |
fa0f0f45 | 269 | fatal("no matching cipher found: client %s server %s", |
270 | client, server); | |
e9702f7d | 271 | if ((enc->cipher = cipher_by_name(name)) == NULL) |
3c0ef626 | 272 | fatal("matching cipher is not supported: %s", name); |
273 | enc->name = name; | |
274 | enc->enabled = 0; | |
275 | enc->iv = NULL; | |
276 | enc->key = NULL; | |
e9702f7d | 277 | enc->key_len = cipher_keylen(enc->cipher); |
278 | enc->block_size = cipher_blocksize(enc->cipher); | |
3c0ef626 | 279 | } |
30460aeb | 280 | |
3c0ef626 | 281 | static void |
282 | choose_mac(Mac *mac, char *client, char *server) | |
283 | { | |
284 | char *name = match_list(client, server, NULL); | |
285 | if (name == NULL) | |
fa0f0f45 | 286 | fatal("no matching mac found: client %s server %s", |
287 | client, server); | |
288 | if (mac_setup(mac, name) < 0) | |
3c0ef626 | 289 | fatal("unsupported mac %s", name); |
290 | /* truncate the key */ | |
291 | if (datafellows & SSH_BUG_HMAC) | |
292 | mac->key_len = 16; | |
293 | mac->name = name; | |
294 | mac->key = NULL; | |
295 | mac->enabled = 0; | |
296 | } | |
30460aeb | 297 | |
3c0ef626 | 298 | static void |
299 | choose_comp(Comp *comp, char *client, char *server) | |
300 | { | |
301 | char *name = match_list(client, server, NULL); | |
302 | if (name == NULL) | |
303 | fatal("no matching comp found: client %s server %s", client, server); | |
2ce0bfe4 | 304 | if (strcmp(name, "zlib@openssh.com") == 0) { |
305 | comp->type = COMP_DELAYED; | |
306 | } else if (strcmp(name, "zlib") == 0) { | |
307 | comp->type = COMP_ZLIB; | |
3c0ef626 | 308 | } else if (strcmp(name, "none") == 0) { |
2ce0bfe4 | 309 | comp->type = COMP_NONE; |
3c0ef626 | 310 | } else { |
311 | fatal("unsupported comp %s", name); | |
312 | } | |
313 | comp->name = name; | |
314 | } | |
30460aeb | 315 | |
3c0ef626 | 316 | static void |
317 | choose_kex(Kex *k, char *client, char *server) | |
318 | { | |
319 | k->name = match_list(client, server, NULL); | |
320 | if (k->name == NULL) | |
fa0f0f45 | 321 | fatal("Unable to negotiate a key exchange method"); |
3c0ef626 | 322 | if (strcmp(k->name, KEX_DH1) == 0) { |
8afc6a66 | 323 | k->kex_type = KEX_DH_GRP1_SHA1; |
08822d99 | 324 | k->evp_md = EVP_sha1(); |
7e82606e | 325 | } else if (strcmp(k->name, KEX_DH14) == 0) { |
326 | k->kex_type = KEX_DH_GRP14_SHA1; | |
08822d99 | 327 | k->evp_md = EVP_sha1(); |
328 | } else if (strcmp(k->name, KEX_DHGEX_SHA1) == 0) { | |
8afc6a66 | 329 | k->kex_type = KEX_DH_GEX_SHA1; |
08822d99 | 330 | k->evp_md = EVP_sha1(); |
f713db99 | 331 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L |
332 | } else if (strcmp(k->name, KEX_DHGEX_SHA256) == 0) { | |
333 | k->kex_type = KEX_DH_GEX_SHA256; | |
334 | k->evp_md = evp_ssh_sha256(); | |
335 | #endif | |
5598e598 | 336 | #ifdef GSSAPI |
fe4ad273 | 337 | } else if (strncmp(k->name, KEX_GSS_GEX_SHA1_ID, |
f713db99 | 338 | sizeof(KEX_GSS_GEX_SHA1_ID) - 1) == 0) { |
fe4ad273 | 339 | k->kex_type = KEX_GSS_GEX_SHA1; |
08822d99 | 340 | k->evp_md = EVP_sha1(); |
c06c9ae8 | 341 | } else if (strncmp(k->name, KEX_GSS_GRP1_SHA1_ID, |
f713db99 | 342 | sizeof(KEX_GSS_GRP1_SHA1_ID) - 1) == 0) { |
8afc6a66 | 343 | k->kex_type = KEX_GSS_GRP1_SHA1; |
08822d99 | 344 | k->evp_md = EVP_sha1(); |
f713db99 | 345 | } else if (strncmp(k->name, KEX_GSS_GRP14_SHA1_ID, |
346 | sizeof(KEX_GSS_GRP14_SHA1_ID) - 1) == 0) { | |
347 | k->kex_type = KEX_GSS_GRP14_SHA1; | |
348 | k->evp_md = EVP_sha1(); | |
5598e598 | 349 | #endif |
3c0ef626 | 350 | } else |
351 | fatal("bad kex alg %s", k->name); | |
352 | } | |
08822d99 | 353 | |
3c0ef626 | 354 | static void |
355 | choose_hostkeyalg(Kex *k, char *client, char *server) | |
356 | { | |
357 | char *hostkeyalg = match_list(client, server, NULL); | |
358 | if (hostkeyalg == NULL) | |
359 | fatal("no hostkey alg"); | |
360 | k->hostkey_type = key_type_from_name(hostkeyalg); | |
361 | if (k->hostkey_type == KEY_UNSPEC) | |
362 | fatal("bad hostkey alg '%s'", hostkeyalg); | |
363 | xfree(hostkeyalg); | |
364 | } | |
365 | ||
540d72c3 | 366 | static int |
8afc6a66 | 367 | proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) |
368 | { | |
369 | static int check[] = { | |
370 | PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 | |
371 | }; | |
372 | int *idx; | |
373 | char *p; | |
374 | ||
375 | for (idx = &check[0]; *idx != -1; idx++) { | |
376 | if ((p = strchr(my[*idx], ',')) != NULL) | |
377 | *p = '\0'; | |
378 | if ((p = strchr(peer[*idx], ',')) != NULL) | |
379 | *p = '\0'; | |
380 | if (strcmp(my[*idx], peer[*idx]) != 0) { | |
381 | debug2("proposal mismatch: my %s peer %s", | |
382 | my[*idx], peer[*idx]); | |
383 | return (0); | |
384 | } | |
385 | } | |
386 | debug2("proposals match"); | |
387 | return (1); | |
388 | } | |
389 | ||
3c0ef626 | 390 | static void |
391 | kex_choose_conf(Kex *kex) | |
392 | { | |
393 | Newkeys *newkeys; | |
394 | char **my, **peer; | |
395 | char **cprop, **sprop; | |
396 | int nenc, nmac, ncomp; | |
2ce0bfe4 | 397 | u_int mode, ctos, need; |
8afc6a66 | 398 | int first_kex_follows, type; |
fa7499cc | 399 | int log_flag = 0; |
3c0ef626 | 400 | |
6df46d40 | 401 | int auth_flag; |
402 | ||
403 | auth_flag = packet_authentication_state(); | |
404 | ||
405 | debug ("AUTH STATE IS %d", auth_flag); | |
406 | ||
8afc6a66 | 407 | my = kex_buf2prop(&kex->my, NULL); |
408 | peer = kex_buf2prop(&kex->peer, &first_kex_follows); | |
3c0ef626 | 409 | |
410 | if (kex->server) { | |
411 | cprop=peer; | |
412 | sprop=my; | |
413 | } else { | |
414 | cprop=my; | |
415 | sprop=peer; | |
416 | } | |
417 | ||
418 | /* Algorithm Negotiation */ | |
419 | for (mode = 0; mode < MODE_MAX; mode++) { | |
30460aeb | 420 | newkeys = xcalloc(1, sizeof(*newkeys)); |
3c0ef626 | 421 | kex->newkeys[mode] = newkeys; |
fa0f0f45 | 422 | ctos = (!kex->server && mode == MODE_OUT) || |
423 | (kex->server && mode == MODE_IN); | |
3c0ef626 | 424 | nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; |
425 | nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; | |
426 | ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; | |
427 | choose_enc (&newkeys->enc, cprop[nenc], sprop[nenc]); | |
428 | choose_mac (&newkeys->mac, cprop[nmac], sprop[nmac]); | |
429 | choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); | |
6df46d40 | 430 | debug("REQUESTED ENC.NAME is '%s'", newkeys->enc.name); |
431 | if (strcmp(newkeys->enc.name, "none") == 0) { | |
432 | debug("Requesting NONE. Authflag is %d", auth_flag); | |
433 | if (auth_flag == 1) { | |
434 | debug("None requested post authentication."); | |
435 | } else { | |
436 | fatal("Pre-authentication none cipher requests are not allowed."); | |
437 | } | |
438 | } | |
3c0ef626 | 439 | debug("kex: %s %s %s %s", |
440 | ctos ? "client->server" : "server->client", | |
441 | newkeys->enc.name, | |
442 | newkeys->mac.name, | |
443 | newkeys->comp.name); | |
fa7499cc | 444 | /* client starts withctos = 0 && log flag = 0 and no log*/ |
445 | /* 2nd client pass ctos=1 and flag = 1 so no log*/ | |
446 | /* server starts with ctos =1 && log_flag = 0 so log */ | |
447 | /* 2nd sever pass ctos = 1 && log flag = 1 so no log*/ | |
448 | /* -cjr*/ | |
449 | if (ctos && !log_flag) { | |
450 | logit("SSH: Server;Ltype: Kex;Remote: %s-%d;Enc: %s;MAC: %s;Comp: %s", | |
451 | get_remote_ipaddr(), | |
452 | get_remote_port(), | |
453 | newkeys->enc.name, | |
454 | newkeys->mac.name, | |
455 | newkeys->comp.name); | |
456 | } | |
457 | log_flag = 1; | |
3c0ef626 | 458 | } |
459 | choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); | |
460 | choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], | |
461 | sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); | |
462 | need = 0; | |
463 | for (mode = 0; mode < MODE_MAX; mode++) { | |
464 | newkeys = kex->newkeys[mode]; | |
e9702f7d | 465 | if (need < newkeys->enc.key_len) |
466 | need = newkeys->enc.key_len; | |
467 | if (need < newkeys->enc.block_size) | |
468 | need = newkeys->enc.block_size; | |
3c0ef626 | 469 | if (need < newkeys->mac.key_len) |
470 | need = newkeys->mac.key_len; | |
471 | } | |
472 | /* XXX need runden? */ | |
473 | kex->we_need = need; | |
474 | ||
8afc6a66 | 475 | /* ignore the next message if the proposals do not match */ |
540d72c3 | 476 | if (first_kex_follows && !proposals_match(my, peer) && |
2ce0bfe4 | 477 | !(datafellows & SSH_BUG_FIRSTKEX)) { |
8afc6a66 | 478 | type = packet_read(); |
479 | debug2("skipping next packet (type %u)", type); | |
480 | } | |
481 | ||
3c0ef626 | 482 | kex_prop_free(my); |
483 | kex_prop_free(peer); | |
484 | } | |
485 | ||
486 | static u_char * | |
08822d99 | 487 | derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, |
488 | BIGNUM *shared_secret) | |
3c0ef626 | 489 | { |
490 | Buffer b; | |
3c0ef626 | 491 | EVP_MD_CTX md; |
492 | char c = id; | |
2ce0bfe4 | 493 | u_int have; |
08822d99 | 494 | int mdsz; |
2ce0bfe4 | 495 | u_char *digest; |
496 | ||
08822d99 | 497 | if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0) |
498 | fatal("bad kex md size %d", mdsz); | |
30460aeb | 499 | digest = xmalloc(roundup(need, mdsz)); |
3c0ef626 | 500 | |
501 | buffer_init(&b); | |
502 | buffer_put_bignum2(&b, shared_secret); | |
503 | ||
504 | /* K1 = HASH(K || H || "A" || session_id) */ | |
08822d99 | 505 | EVP_DigestInit(&md, kex->evp_md); |
3c0ef626 | 506 | if (!(datafellows & SSH_BUG_DERIVEKEY)) |
507 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
08822d99 | 508 | EVP_DigestUpdate(&md, hash, hashlen); |
3c0ef626 | 509 | EVP_DigestUpdate(&md, &c, 1); |
510 | EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len); | |
511 | EVP_DigestFinal(&md, digest, NULL); | |
512 | ||
513 | /* | |
514 | * expand key: | |
515 | * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) | |
516 | * Key = K1 || K2 || ... || Kn | |
517 | */ | |
518 | for (have = mdsz; need > have; have += mdsz) { | |
08822d99 | 519 | EVP_DigestInit(&md, kex->evp_md); |
3c0ef626 | 520 | if (!(datafellows & SSH_BUG_DERIVEKEY)) |
521 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
08822d99 | 522 | EVP_DigestUpdate(&md, hash, hashlen); |
3c0ef626 | 523 | EVP_DigestUpdate(&md, digest, have); |
524 | EVP_DigestFinal(&md, digest + have, NULL); | |
525 | } | |
526 | buffer_free(&b); | |
527 | #ifdef DEBUG_KEX | |
528 | fprintf(stderr, "key '%c'== ", c); | |
529 | dump_digest("key", digest, need); | |
530 | #endif | |
531 | return digest; | |
532 | } | |
533 | ||
534 | Newkeys *current_keys[MODE_MAX]; | |
535 | ||
536 | #define NKEYS 6 | |
537 | void | |
08822d99 | 538 | kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret) |
3c0ef626 | 539 | { |
540 | u_char *keys[NKEYS]; | |
2ce0bfe4 | 541 | u_int i, mode, ctos; |
3c0ef626 | 542 | |
08822d99 | 543 | for (i = 0; i < NKEYS; i++) { |
544 | keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, | |
545 | shared_secret); | |
546 | } | |
3c0ef626 | 547 | |
8afc6a66 | 548 | debug2("kex_derive_keys"); |
3c0ef626 | 549 | for (mode = 0; mode < MODE_MAX; mode++) { |
550 | current_keys[mode] = kex->newkeys[mode]; | |
551 | kex->newkeys[mode] = NULL; | |
30460aeb | 552 | ctos = (!kex->server && mode == MODE_OUT) || |
553 | (kex->server && mode == MODE_IN); | |
3c0ef626 | 554 | current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; |
555 | current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; | |
556 | current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; | |
557 | } | |
558 | } | |
559 | ||
560 | Newkeys * | |
561 | kex_get_newkeys(int mode) | |
562 | { | |
563 | Newkeys *ret; | |
564 | ||
565 | ret = current_keys[mode]; | |
566 | current_keys[mode] = NULL; | |
567 | return ret; | |
568 | } | |
569 | ||
7e82606e | 570 | void |
571 | derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, | |
572 | u_int8_t cookie[8], u_int8_t id[16]) | |
573 | { | |
574 | const EVP_MD *evp_md = EVP_md5(); | |
575 | EVP_MD_CTX md; | |
576 | u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE]; | |
577 | int len; | |
578 | ||
579 | EVP_DigestInit(&md, evp_md); | |
580 | ||
581 | len = BN_num_bytes(host_modulus); | |
2ce0bfe4 | 582 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) |
7e82606e | 583 | fatal("%s: bad host modulus (len %d)", __func__, len); |
584 | BN_bn2bin(host_modulus, nbuf); | |
585 | EVP_DigestUpdate(&md, nbuf, len); | |
586 | ||
587 | len = BN_num_bytes(server_modulus); | |
2ce0bfe4 | 588 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) |
7e82606e | 589 | fatal("%s: bad server modulus (len %d)", __func__, len); |
590 | BN_bn2bin(server_modulus, nbuf); | |
591 | EVP_DigestUpdate(&md, nbuf, len); | |
592 | ||
593 | EVP_DigestUpdate(&md, cookie, 8); | |
594 | ||
595 | EVP_DigestFinal(&md, obuf, NULL); | |
596 | memcpy(id, obuf, 16); | |
597 | ||
598 | memset(nbuf, 0, sizeof(nbuf)); | |
599 | memset(obuf, 0, sizeof(obuf)); | |
600 | memset(&md, 0, sizeof(md)); | |
601 | } | |
602 | ||
3c0ef626 | 603 | #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) |
604 | void | |
605 | dump_digest(char *msg, u_char *digest, int len) | |
606 | { | |
2ce0bfe4 | 607 | u_int i; |
3c0ef626 | 608 | |
609 | fprintf(stderr, "%s\n", msg); | |
0b90ac93 | 610 | for (i = 0; i < len; i++) { |
3c0ef626 | 611 | fprintf(stderr, "%02x", digest[i]); |
612 | if (i%32 == 31) | |
613 | fprintf(stderr, "\n"); | |
614 | else if (i%8 == 7) | |
615 | fprintf(stderr, " "); | |
616 | } | |
617 | fprintf(stderr, "\n"); | |
618 | } | |
619 | #endif |