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1975fb98 | 1 | /* $OpenBSD: kex.c,v 1.80 2008/09/06 12:24:13 djm Exp $ */ |
4f8c6159 | 2 | /* |
a96070d4 | 3 | * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. |
4f8c6159 | 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. | |
4f8c6159 | 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" | |
4f8c6159 | 27 | |
536c14e8 | 28 | #include <sys/param.h> |
29 | ||
31652869 | 30 | #include <signal.h> |
24436b92 | 31 | #include <stdarg.h> |
cf851879 | 32 | #include <stdio.h> |
ffa517a8 | 33 | #include <stdlib.h> |
00146caa | 34 | #include <string.h> |
35 | ||
31652869 | 36 | #include <openssl/crypto.h> |
37 | ||
42f11eb2 | 38 | #include "xmalloc.h" |
31652869 | 39 | #include "ssh2.h" |
42f11eb2 | 40 | #include "buffer.h" |
42f11eb2 | 41 | #include "packet.h" |
42 | #include "compat.h" | |
43 | #include "cipher.h" | |
fa08c86b | 44 | #include "key.h" |
31652869 | 45 | #include "kex.h" |
42f11eb2 | 46 | #include "log.h" |
b2552997 | 47 | #include "mac.h" |
cab80f75 | 48 | #include "match.h" |
a5c9ffdb | 49 | #include "dispatch.h" |
1853d1ef | 50 | #include "monitor.h" |
4f8c6159 | 51 | |
71276795 | 52 | #define KEX_COOKIE_LEN 16 |
53 | ||
30baf904 | 54 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L |
55 | # if defined(HAVE_EVP_SHA256) | |
13ff27b7 | 56 | # define evp_ssh_sha256 EVP_sha256 |
30baf904 | 57 | # else |
2ff8003a | 58 | extern const EVP_MD *evp_ssh_sha256(void); |
30baf904 | 59 | # endif |
b1f0c612 | 60 | #endif |
2ff8003a | 61 | |
396c147e | 62 | /* prototype */ |
63 | static void kex_kexinit_finish(Kex *); | |
64 | static void kex_choose_conf(Kex *); | |
a5c9ffdb | 65 | |
66 | /* put algorithm proposal into buffer */ | |
396c147e | 67 | static void |
a5c9ffdb | 68 | kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) |
4f8c6159 | 69 | { |
2ceb8101 | 70 | u_int i; |
a5c9ffdb | 71 | |
72 | buffer_clear(b); | |
76bf34f1 | 73 | /* |
74 | * add a dummy cookie, the cookie will be overwritten by | |
75 | * kex_send_kexinit(), each time a kexinit is set | |
76 | */ | |
77 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
78 | buffer_put_char(b, 0); | |
4f8c6159 | 79 | for (i = 0; i < PROPOSAL_MAX; i++) |
a5c9ffdb | 80 | buffer_put_cstring(b, proposal[i]); |
81 | buffer_put_char(b, 0); /* first_kex_packet_follows */ | |
82 | buffer_put_int(b, 0); /* uint32 reserved */ | |
4f8c6159 | 83 | } |
84 | ||
a5c9ffdb | 85 | /* parse buffer and return algorithm proposal */ |
396c147e | 86 | static char ** |
eed8e583 | 87 | kex_buf2prop(Buffer *raw, int *first_kex_follows) |
71276795 | 88 | { |
a5c9ffdb | 89 | Buffer b; |
68525040 | 90 | u_int i; |
a5c9ffdb | 91 | char **proposal; |
71276795 | 92 | |
52e3daed | 93 | proposal = xcalloc(PROPOSAL_MAX, sizeof(char *)); |
a5c9ffdb | 94 | |
95 | buffer_init(&b); | |
96 | buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); | |
71276795 | 97 | /* skip cookie */ |
98 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
a5c9ffdb | 99 | buffer_get_char(&b); |
71276795 | 100 | /* extract kex init proposal strings */ |
101 | for (i = 0; i < PROPOSAL_MAX; i++) { | |
a5c9ffdb | 102 | proposal[i] = buffer_get_string(&b,NULL); |
103 | debug2("kex_parse_kexinit: %s", proposal[i]); | |
71276795 | 104 | } |
a5c9ffdb | 105 | /* first kex follows / reserved */ |
106 | i = buffer_get_char(&b); | |
eed8e583 | 107 | if (first_kex_follows != NULL) |
108 | *first_kex_follows = i; | |
a5c9ffdb | 109 | debug2("kex_parse_kexinit: first_kex_follows %d ", i); |
110 | i = buffer_get_int(&b); | |
68525040 | 111 | debug2("kex_parse_kexinit: reserved %u ", i); |
a5c9ffdb | 112 | buffer_free(&b); |
113 | return proposal; | |
71276795 | 114 | } |
115 | ||
396c147e | 116 | static void |
a5c9ffdb | 117 | kex_prop_free(char **proposal) |
4f8c6159 | 118 | { |
2ceb8101 | 119 | u_int i; |
a5c9ffdb | 120 | |
121 | for (i = 0; i < PROPOSAL_MAX; i++) | |
122 | xfree(proposal[i]); | |
123 | xfree(proposal); | |
4f8c6159 | 124 | } |
125 | ||
68525040 | 126 | /* ARGSUSED */ |
396c147e | 127 | static void |
7819b5c3 | 128 | kex_protocol_error(int type, u_int32_t seq, void *ctxt) |
4f8c6159 | 129 | { |
7819b5c3 | 130 | error("Hm, kex protocol error: type %d seq %u", type, seq); |
a5c9ffdb | 131 | } |
4f8c6159 | 132 | |
396c147e | 133 | static void |
9d726f16 | 134 | kex_reset_dispatch(void) |
7a37c112 | 135 | { |
6367063f | 136 | dispatch_range(SSH2_MSG_TRANSPORT_MIN, |
137 | SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); | |
9d726f16 | 138 | dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); |
7a37c112 | 139 | } |
140 | ||
a5c9ffdb | 141 | void |
d8ee838b | 142 | kex_finish(Kex *kex) |
a5c9ffdb | 143 | { |
9d726f16 | 144 | kex_reset_dispatch(); |
d8ee838b | 145 | |
a5c9ffdb | 146 | packet_start(SSH2_MSG_NEWKEYS); |
147 | packet_send(); | |
148 | /* packet_write_wait(); */ | |
149 | debug("SSH2_MSG_NEWKEYS sent"); | |
4f8c6159 | 150 | |
a77673cc | 151 | debug("expecting SSH2_MSG_NEWKEYS"); |
54a5250f | 152 | packet_read_expect(SSH2_MSG_NEWKEYS); |
b967d870 | 153 | packet_check_eom(); |
a5c9ffdb | 154 | debug("SSH2_MSG_NEWKEYS received"); |
a7ca6275 | 155 | |
c422989b | 156 | kex->done = 1; |
a5c9ffdb | 157 | buffer_clear(&kex->peer); |
d1ac6175 | 158 | /* buffer_clear(&kex->my); */ |
a5c9ffdb | 159 | kex->flags &= ~KEX_INIT_SENT; |
a7ca6275 | 160 | xfree(kex->name); |
161 | kex->name = NULL; | |
4f8c6159 | 162 | } |
163 | ||
a5c9ffdb | 164 | void |
165 | kex_send_kexinit(Kex *kex) | |
94ec8c6b | 166 | { |
ca75d7de | 167 | u_int32_t rnd = 0; |
76bf34f1 | 168 | u_char *cookie; |
2ceb8101 | 169 | u_int i; |
76bf34f1 | 170 | |
7a37c112 | 171 | if (kex == NULL) { |
172 | error("kex_send_kexinit: no kex, cannot rekey"); | |
173 | return; | |
174 | } | |
d8ee838b | 175 | if (kex->flags & KEX_INIT_SENT) { |
176 | debug("KEX_INIT_SENT"); | |
177 | return; | |
178 | } | |
c422989b | 179 | kex->done = 0; |
76bf34f1 | 180 | |
181 | /* generate a random cookie */ | |
182 | if (buffer_len(&kex->my) < KEX_COOKIE_LEN) | |
183 | fatal("kex_send_kexinit: kex proposal too short"); | |
184 | cookie = buffer_ptr(&kex->my); | |
185 | for (i = 0; i < KEX_COOKIE_LEN; i++) { | |
186 | if (i % 4 == 0) | |
ca75d7de | 187 | rnd = arc4random(); |
188 | cookie[i] = rnd; | |
189 | rnd >>= 8; | |
76bf34f1 | 190 | } |
a5c9ffdb | 191 | packet_start(SSH2_MSG_KEXINIT); |
192 | packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); | |
193 | packet_send(); | |
194 | debug("SSH2_MSG_KEXINIT sent"); | |
195 | kex->flags |= KEX_INIT_SENT; | |
196 | } | |
2b87da3b | 197 | |
68525040 | 198 | /* ARGSUSED */ |
a5c9ffdb | 199 | void |
7819b5c3 | 200 | kex_input_kexinit(int type, u_int32_t seq, void *ctxt) |
a5c9ffdb | 201 | { |
202 | char *ptr; | |
2ceb8101 | 203 | u_int i, dlen; |
a5c9ffdb | 204 | Kex *kex = (Kex *)ctxt; |
94ec8c6b | 205 | |
a5c9ffdb | 206 | debug("SSH2_MSG_KEXINIT received"); |
7a37c112 | 207 | if (kex == NULL) |
208 | fatal("kex_input_kexinit: no kex, cannot rekey"); | |
94ec8c6b | 209 | |
a5c9ffdb | 210 | ptr = packet_get_raw(&dlen); |
211 | buffer_append(&kex->peer, ptr, dlen); | |
94ec8c6b | 212 | |
bbb4cc1b | 213 | /* discard packet */ |
214 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
215 | packet_get_char(); | |
216 | for (i = 0; i < PROPOSAL_MAX; i++) | |
217 | xfree(packet_get_string(NULL)); | |
1169c3df | 218 | (void) packet_get_char(); |
219 | (void) packet_get_int(); | |
95500969 | 220 | packet_check_eom(); |
bbb4cc1b | 221 | |
a5c9ffdb | 222 | kex_kexinit_finish(kex); |
94ec8c6b | 223 | } |
224 | ||
a5c9ffdb | 225 | Kex * |
d8ee838b | 226 | kex_setup(char *proposal[PROPOSAL_MAX]) |
4f8c6159 | 227 | { |
a5c9ffdb | 228 | Kex *kex; |
4f8c6159 | 229 | |
52e3daed | 230 | kex = xcalloc(1, sizeof(*kex)); |
a5c9ffdb | 231 | buffer_init(&kex->peer); |
232 | buffer_init(&kex->my); | |
233 | kex_prop2buf(&kex->my, proposal); | |
c422989b | 234 | kex->done = 0; |
a5c9ffdb | 235 | |
236 | kex_send_kexinit(kex); /* we start */ | |
9d726f16 | 237 | kex_reset_dispatch(); |
7a37c112 | 238 | |
a5c9ffdb | 239 | return kex; |
240 | } | |
4f8c6159 | 241 | |
396c147e | 242 | static void |
a5c9ffdb | 243 | kex_kexinit_finish(Kex *kex) |
244 | { | |
245 | if (!(kex->flags & KEX_INIT_SENT)) | |
246 | kex_send_kexinit(kex); | |
247 | ||
248 | kex_choose_conf(kex); | |
249 | ||
98a58eda | 250 | if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX && |
251 | kex->kex[kex->kex_type] != NULL) { | |
252 | (kex->kex[kex->kex_type])(kex); | |
253 | } else { | |
a5c9ffdb | 254 | fatal("Unsupported key exchange %d", kex->kex_type); |
4f8c6159 | 255 | } |
4f8c6159 | 256 | } |
257 | ||
396c147e | 258 | static void |
4f8c6159 | 259 | choose_enc(Enc *enc, char *client, char *server) |
260 | { | |
cab80f75 | 261 | char *name = match_list(client, server, NULL); |
4f8c6159 | 262 | if (name == NULL) |
68525040 | 263 | fatal("no matching cipher found: client %s server %s", |
264 | client, server); | |
3ee832e5 | 265 | if ((enc->cipher = cipher_by_name(name)) == NULL) |
94ec8c6b | 266 | fatal("matching cipher is not supported: %s", name); |
4f8c6159 | 267 | enc->name = name; |
268 | enc->enabled = 0; | |
269 | enc->iv = NULL; | |
270 | enc->key = NULL; | |
3ee832e5 | 271 | enc->key_len = cipher_keylen(enc->cipher); |
272 | enc->block_size = cipher_blocksize(enc->cipher); | |
4f8c6159 | 273 | } |
a7137f6b | 274 | |
396c147e | 275 | static void |
4f8c6159 | 276 | choose_mac(Mac *mac, char *client, char *server) |
277 | { | |
cab80f75 | 278 | char *name = match_list(client, server, NULL); |
4f8c6159 | 279 | if (name == NULL) |
68525040 | 280 | fatal("no matching mac found: client %s server %s", |
281 | client, server); | |
a3de8da1 | 282 | if (mac_setup(mac, name) < 0) |
4f8c6159 | 283 | fatal("unsupported mac %s", name); |
b2552997 | 284 | /* truncate the key */ |
285 | if (datafellows & SSH_BUG_HMAC) | |
286 | mac->key_len = 16; | |
4f8c6159 | 287 | mac->name = name; |
4f8c6159 | 288 | mac->key = NULL; |
289 | mac->enabled = 0; | |
290 | } | |
a7137f6b | 291 | |
396c147e | 292 | static void |
4f8c6159 | 293 | choose_comp(Comp *comp, char *client, char *server) |
294 | { | |
cab80f75 | 295 | char *name = match_list(client, server, NULL); |
4f8c6159 | 296 | if (name == NULL) |
297 | fatal("no matching comp found: client %s server %s", client, server); | |
07200973 | 298 | if (strcmp(name, "zlib@openssh.com") == 0) { |
299 | comp->type = COMP_DELAYED; | |
300 | } else if (strcmp(name, "zlib") == 0) { | |
301 | comp->type = COMP_ZLIB; | |
4f8c6159 | 302 | } else if (strcmp(name, "none") == 0) { |
07200973 | 303 | comp->type = COMP_NONE; |
4f8c6159 | 304 | } else { |
305 | fatal("unsupported comp %s", name); | |
306 | } | |
307 | comp->name = name; | |
308 | } | |
a7137f6b | 309 | |
396c147e | 310 | static void |
4f8c6159 | 311 | choose_kex(Kex *k, char *client, char *server) |
312 | { | |
cab80f75 | 313 | k->name = match_list(client, server, NULL); |
4f8c6159 | 314 | if (k->name == NULL) |
68525040 | 315 | fatal("Unable to negotiate a key exchange method"); |
94ec8c6b | 316 | if (strcmp(k->name, KEX_DH1) == 0) { |
98a58eda | 317 | k->kex_type = KEX_DH_GRP1_SHA1; |
47e5dc72 | 318 | k->evp_md = EVP_sha1(); |
41e5bd9a | 319 | } else if (strcmp(k->name, KEX_DH14) == 0) { |
320 | k->kex_type = KEX_DH_GRP14_SHA1; | |
47e5dc72 | 321 | k->evp_md = EVP_sha1(); |
322 | } else if (strcmp(k->name, KEX_DHGEX_SHA1) == 0) { | |
98a58eda | 323 | k->kex_type = KEX_DH_GEX_SHA1; |
47e5dc72 | 324 | k->evp_md = EVP_sha1(); |
30baf904 | 325 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L |
2ff8003a | 326 | } else if (strcmp(k->name, KEX_DHGEX_SHA256) == 0) { |
327 | k->kex_type = KEX_DH_GEX_SHA256; | |
328 | k->evp_md = evp_ssh_sha256(); | |
30baf904 | 329 | #endif |
94ec8c6b | 330 | } else |
4f8c6159 | 331 | fatal("bad kex alg %s", k->name); |
332 | } | |
47e5dc72 | 333 | |
396c147e | 334 | static void |
4f8c6159 | 335 | choose_hostkeyalg(Kex *k, char *client, char *server) |
336 | { | |
cab80f75 | 337 | char *hostkeyalg = match_list(client, server, NULL); |
fa08c86b | 338 | if (hostkeyalg == NULL) |
4f8c6159 | 339 | fatal("no hostkey alg"); |
fa08c86b | 340 | k->hostkey_type = key_type_from_name(hostkeyalg); |
341 | if (k->hostkey_type == KEY_UNSPEC) | |
342 | fatal("bad hostkey alg '%s'", hostkeyalg); | |
eea39c02 | 343 | xfree(hostkeyalg); |
4f8c6159 | 344 | } |
345 | ||
aff51935 | 346 | static int |
eed8e583 | 347 | proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) |
348 | { | |
349 | static int check[] = { | |
350 | PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 | |
351 | }; | |
352 | int *idx; | |
353 | char *p; | |
354 | ||
355 | for (idx = &check[0]; *idx != -1; idx++) { | |
356 | if ((p = strchr(my[*idx], ',')) != NULL) | |
357 | *p = '\0'; | |
358 | if ((p = strchr(peer[*idx], ',')) != NULL) | |
359 | *p = '\0'; | |
360 | if (strcmp(my[*idx], peer[*idx]) != 0) { | |
361 | debug2("proposal mismatch: my %s peer %s", | |
362 | my[*idx], peer[*idx]); | |
363 | return (0); | |
364 | } | |
365 | } | |
366 | debug2("proposals match"); | |
367 | return (1); | |
368 | } | |
369 | ||
396c147e | 370 | static void |
d1ac6175 | 371 | kex_choose_conf(Kex *kex) |
4f8c6159 | 372 | { |
d1ac6175 | 373 | Newkeys *newkeys; |
a5c9ffdb | 374 | char **my, **peer; |
375 | char **cprop, **sprop; | |
d1ac6175 | 376 | int nenc, nmac, ncomp; |
2ceb8101 | 377 | u_int mode, ctos, need; |
eed8e583 | 378 | int first_kex_follows, type; |
4f8c6159 | 379 | |
eed8e583 | 380 | my = kex_buf2prop(&kex->my, NULL); |
381 | peer = kex_buf2prop(&kex->peer, &first_kex_follows); | |
a5c9ffdb | 382 | |
d1ac6175 | 383 | if (kex->server) { |
a5c9ffdb | 384 | cprop=peer; |
385 | sprop=my; | |
386 | } else { | |
387 | cprop=my; | |
388 | sprop=peer; | |
389 | } | |
4f8c6159 | 390 | |
c422989b | 391 | /* Algorithm Negotiation */ |
4f8c6159 | 392 | for (mode = 0; mode < MODE_MAX; mode++) { |
52e3daed | 393 | newkeys = xcalloc(1, sizeof(*newkeys)); |
c422989b | 394 | kex->newkeys[mode] = newkeys; |
68525040 | 395 | ctos = (!kex->server && mode == MODE_OUT) || |
396 | (kex->server && mode == MODE_IN); | |
4f8c6159 | 397 | nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; |
398 | nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; | |
399 | ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; | |
d1ac6175 | 400 | choose_enc (&newkeys->enc, cprop[nenc], sprop[nenc]); |
401 | choose_mac (&newkeys->mac, cprop[nmac], sprop[nmac]); | |
402 | choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); | |
4f8c6159 | 403 | debug("kex: %s %s %s %s", |
404 | ctos ? "client->server" : "server->client", | |
d1ac6175 | 405 | newkeys->enc.name, |
406 | newkeys->mac.name, | |
407 | newkeys->comp.name); | |
4f8c6159 | 408 | } |
d1ac6175 | 409 | choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); |
410 | choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], | |
4f8c6159 | 411 | sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); |
4f8c6159 | 412 | need = 0; |
413 | for (mode = 0; mode < MODE_MAX; mode++) { | |
c422989b | 414 | newkeys = kex->newkeys[mode]; |
3ee832e5 | 415 | if (need < newkeys->enc.key_len) |
416 | need = newkeys->enc.key_len; | |
417 | if (need < newkeys->enc.block_size) | |
418 | need = newkeys->enc.block_size; | |
d1ac6175 | 419 | if (need < newkeys->mac.key_len) |
420 | need = newkeys->mac.key_len; | |
4f8c6159 | 421 | } |
71276795 | 422 | /* XXX need runden? */ |
d1ac6175 | 423 | kex->we_need = need; |
a5c9ffdb | 424 | |
eed8e583 | 425 | /* ignore the next message if the proposals do not match */ |
aff51935 | 426 | if (first_kex_follows && !proposals_match(my, peer) && |
4e2e5cfd | 427 | !(datafellows & SSH_BUG_FIRSTKEX)) { |
eed8e583 | 428 | type = packet_read(); |
429 | debug2("skipping next packet (type %u)", type); | |
430 | } | |
431 | ||
a5c9ffdb | 432 | kex_prop_free(my); |
433 | kex_prop_free(peer); | |
a5c9ffdb | 434 | } |
435 | ||
396c147e | 436 | static u_char * |
47e5dc72 | 437 | derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, |
438 | BIGNUM *shared_secret) | |
a5c9ffdb | 439 | { |
440 | Buffer b; | |
a5c9ffdb | 441 | EVP_MD_CTX md; |
442 | char c = id; | |
2ceb8101 | 443 | u_int have; |
47e5dc72 | 444 | int mdsz; |
2ceb8101 | 445 | u_char *digest; |
56964485 | 446 | |
47e5dc72 | 447 | if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0) |
448 | fatal("bad kex md size %d", mdsz); | |
b4bbf172 | 449 | digest = xmalloc(roundup(need, mdsz)); |
a5c9ffdb | 450 | |
451 | buffer_init(&b); | |
452 | buffer_put_bignum2(&b, shared_secret); | |
453 | ||
c422989b | 454 | /* K1 = HASH(K || H || "A" || session_id) */ |
47e5dc72 | 455 | EVP_DigestInit(&md, kex->evp_md); |
eef7adcb | 456 | if (!(datafellows & SSH_BUG_DERIVEKEY)) |
457 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
47e5dc72 | 458 | EVP_DigestUpdate(&md, hash, hashlen); |
c422989b | 459 | EVP_DigestUpdate(&md, &c, 1); |
d1ac6175 | 460 | EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len); |
a5c9ffdb | 461 | EVP_DigestFinal(&md, digest, NULL); |
462 | ||
c422989b | 463 | /* |
464 | * expand key: | |
465 | * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) | |
466 | * Key = K1 || K2 || ... || Kn | |
467 | */ | |
a5c9ffdb | 468 | for (have = mdsz; need > have; have += mdsz) { |
47e5dc72 | 469 | EVP_DigestInit(&md, kex->evp_md); |
eef7adcb | 470 | if (!(datafellows & SSH_BUG_DERIVEKEY)) |
471 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
47e5dc72 | 472 | EVP_DigestUpdate(&md, hash, hashlen); |
a5c9ffdb | 473 | EVP_DigestUpdate(&md, digest, have); |
474 | EVP_DigestFinal(&md, digest + have, NULL); | |
475 | } | |
476 | buffer_free(&b); | |
477 | #ifdef DEBUG_KEX | |
478 | fprintf(stderr, "key '%c'== ", c); | |
479 | dump_digest("key", digest, need); | |
480 | #endif | |
481 | return digest; | |
4f8c6159 | 482 | } |
483 | ||
c422989b | 484 | Newkeys *current_keys[MODE_MAX]; |
d1ac6175 | 485 | |
cab80f75 | 486 | #define NKEYS 6 |
a5c9ffdb | 487 | void |
47e5dc72 | 488 | kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret) |
4f8c6159 | 489 | { |
1e3b8b07 | 490 | u_char *keys[NKEYS]; |
2ceb8101 | 491 | u_int i, mode, ctos; |
4f8c6159 | 492 | |
47e5dc72 | 493 | for (i = 0; i < NKEYS; i++) { |
494 | keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, | |
495 | shared_secret); | |
496 | } | |
4f8c6159 | 497 | |
a77673cc | 498 | debug2("kex_derive_keys"); |
4f8c6159 | 499 | for (mode = 0; mode < MODE_MAX; mode++) { |
c422989b | 500 | current_keys[mode] = kex->newkeys[mode]; |
501 | kex->newkeys[mode] = NULL; | |
a7137f6b | 502 | ctos = (!kex->server && mode == MODE_OUT) || |
503 | (kex->server && mode == MODE_IN); | |
c422989b | 504 | current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; |
505 | current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; | |
506 | current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; | |
4f8c6159 | 507 | } |
4f8c6159 | 508 | } |
a5c9ffdb | 509 | |
d1ac6175 | 510 | Newkeys * |
511 | kex_get_newkeys(int mode) | |
512 | { | |
c422989b | 513 | Newkeys *ret; |
514 | ||
515 | ret = current_keys[mode]; | |
516 | current_keys[mode] = NULL; | |
517 | return ret; | |
d1ac6175 | 518 | } |
519 | ||
8bbf1fa6 | 520 | void |
521 | derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, | |
522 | u_int8_t cookie[8], u_int8_t id[16]) | |
523 | { | |
524 | const EVP_MD *evp_md = EVP_md5(); | |
525 | EVP_MD_CTX md; | |
526 | u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE]; | |
527 | int len; | |
528 | ||
529 | EVP_DigestInit(&md, evp_md); | |
530 | ||
531 | len = BN_num_bytes(host_modulus); | |
2ceb8101 | 532 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) |
8bbf1fa6 | 533 | fatal("%s: bad host modulus (len %d)", __func__, len); |
534 | BN_bn2bin(host_modulus, nbuf); | |
535 | EVP_DigestUpdate(&md, nbuf, len); | |
536 | ||
537 | len = BN_num_bytes(server_modulus); | |
2ceb8101 | 538 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) |
8bbf1fa6 | 539 | fatal("%s: bad server modulus (len %d)", __func__, len); |
540 | BN_bn2bin(server_modulus, nbuf); | |
541 | EVP_DigestUpdate(&md, nbuf, len); | |
542 | ||
543 | EVP_DigestUpdate(&md, cookie, 8); | |
544 | ||
59657003 | 545 | EVP_DigestFinal(&md, obuf, NULL); |
8bbf1fa6 | 546 | memcpy(id, obuf, 16); |
547 | ||
548 | memset(nbuf, 0, sizeof(nbuf)); | |
549 | memset(obuf, 0, sizeof(obuf)); | |
550 | memset(&md, 0, sizeof(md)); | |
551 | } | |
552 | ||
a5c9ffdb | 553 | #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) |
554 | void | |
555 | dump_digest(char *msg, u_char *digest, int len) | |
556 | { | |
2ceb8101 | 557 | u_int i; |
a5c9ffdb | 558 | |
559 | fprintf(stderr, "%s\n", msg); | |
803c4226 | 560 | for (i = 0; i < len; i++) { |
a5c9ffdb | 561 | fprintf(stderr, "%02x", digest[i]); |
562 | if (i%32 == 31) | |
563 | fprintf(stderr, "\n"); | |
564 | else if (i%8 == 7) | |
565 | fprintf(stderr, " "); | |
566 | } | |
567 | fprintf(stderr, "\n"); | |
568 | } | |
569 | #endif |