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4f8c6159 | 1 | /* |
a96070d4 | 2 | * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. |
4f8c6159 | 3 | * |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
7 | * 1. Redistributions of source code must retain the above copyright | |
8 | * notice, this list of conditions and the following disclaimer. | |
9 | * 2. Redistributions in binary form must reproduce the above copyright | |
10 | * notice, this list of conditions and the following disclaimer in the | |
11 | * documentation and/or other materials provided with the distribution. | |
4f8c6159 | 12 | * |
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
23 | */ | |
24 | ||
25 | #include "includes.h" | |
4f8c6159 | 26 | |
27 | #include <openssl/crypto.h> | |
4f8c6159 | 28 | |
42f11eb2 | 29 | #include "ssh2.h" |
30 | #include "xmalloc.h" | |
31 | #include "buffer.h" | |
32 | #include "bufaux.h" | |
33 | #include "packet.h" | |
34 | #include "compat.h" | |
35 | #include "cipher.h" | |
4f8c6159 | 36 | #include "kex.h" |
fa08c86b | 37 | #include "key.h" |
42f11eb2 | 38 | #include "log.h" |
b2552997 | 39 | #include "mac.h" |
cab80f75 | 40 | #include "match.h" |
a5c9ffdb | 41 | #include "dispatch.h" |
1853d1ef | 42 | #include "monitor.h" |
4f8c6159 | 43 | |
71276795 | 44 | #define KEX_COOKIE_LEN 16 |
45 | ||
30baf904 | 46 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L |
47 | # if defined(HAVE_EVP_SHA256) | |
13ff27b7 | 48 | # define evp_ssh_sha256 EVP_sha256 |
30baf904 | 49 | # else |
2ff8003a | 50 | extern const EVP_MD *evp_ssh_sha256(void); |
30baf904 | 51 | # endif |
b1f0c612 | 52 | #endif |
2ff8003a | 53 | |
396c147e | 54 | /* prototype */ |
55 | static void kex_kexinit_finish(Kex *); | |
56 | static void kex_choose_conf(Kex *); | |
a5c9ffdb | 57 | |
58 | /* put algorithm proposal into buffer */ | |
396c147e | 59 | static void |
a5c9ffdb | 60 | kex_prop2buf(Buffer *b, char *proposal[PROPOSAL_MAX]) |
4f8c6159 | 61 | { |
2ceb8101 | 62 | u_int i; |
a5c9ffdb | 63 | |
64 | buffer_clear(b); | |
76bf34f1 | 65 | /* |
66 | * add a dummy cookie, the cookie will be overwritten by | |
67 | * kex_send_kexinit(), each time a kexinit is set | |
68 | */ | |
69 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
70 | buffer_put_char(b, 0); | |
4f8c6159 | 71 | for (i = 0; i < PROPOSAL_MAX; i++) |
a5c9ffdb | 72 | buffer_put_cstring(b, proposal[i]); |
73 | buffer_put_char(b, 0); /* first_kex_packet_follows */ | |
74 | buffer_put_int(b, 0); /* uint32 reserved */ | |
4f8c6159 | 75 | } |
76 | ||
a5c9ffdb | 77 | /* parse buffer and return algorithm proposal */ |
396c147e | 78 | static char ** |
eed8e583 | 79 | kex_buf2prop(Buffer *raw, int *first_kex_follows) |
71276795 | 80 | { |
a5c9ffdb | 81 | Buffer b; |
71276795 | 82 | int i; |
a5c9ffdb | 83 | char **proposal; |
71276795 | 84 | |
52e3daed | 85 | proposal = xcalloc(PROPOSAL_MAX, sizeof(char *)); |
a5c9ffdb | 86 | |
87 | buffer_init(&b); | |
88 | buffer_append(&b, buffer_ptr(raw), buffer_len(raw)); | |
71276795 | 89 | /* skip cookie */ |
90 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
a5c9ffdb | 91 | buffer_get_char(&b); |
71276795 | 92 | /* extract kex init proposal strings */ |
93 | for (i = 0; i < PROPOSAL_MAX; i++) { | |
a5c9ffdb | 94 | proposal[i] = buffer_get_string(&b,NULL); |
95 | debug2("kex_parse_kexinit: %s", proposal[i]); | |
71276795 | 96 | } |
a5c9ffdb | 97 | /* first kex follows / reserved */ |
98 | i = buffer_get_char(&b); | |
eed8e583 | 99 | if (first_kex_follows != NULL) |
100 | *first_kex_follows = i; | |
a5c9ffdb | 101 | debug2("kex_parse_kexinit: first_kex_follows %d ", i); |
102 | i = buffer_get_int(&b); | |
103 | debug2("kex_parse_kexinit: reserved %d ", i); | |
104 | buffer_free(&b); | |
105 | return proposal; | |
71276795 | 106 | } |
107 | ||
396c147e | 108 | static void |
a5c9ffdb | 109 | kex_prop_free(char **proposal) |
4f8c6159 | 110 | { |
2ceb8101 | 111 | u_int i; |
a5c9ffdb | 112 | |
113 | for (i = 0; i < PROPOSAL_MAX; i++) | |
114 | xfree(proposal[i]); | |
115 | xfree(proposal); | |
4f8c6159 | 116 | } |
117 | ||
396c147e | 118 | static void |
7819b5c3 | 119 | kex_protocol_error(int type, u_int32_t seq, void *ctxt) |
4f8c6159 | 120 | { |
7819b5c3 | 121 | error("Hm, kex protocol error: type %d seq %u", type, seq); |
a5c9ffdb | 122 | } |
4f8c6159 | 123 | |
396c147e | 124 | static void |
9d726f16 | 125 | kex_reset_dispatch(void) |
7a37c112 | 126 | { |
6367063f | 127 | dispatch_range(SSH2_MSG_TRANSPORT_MIN, |
128 | SSH2_MSG_TRANSPORT_MAX, &kex_protocol_error); | |
9d726f16 | 129 | dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); |
7a37c112 | 130 | } |
131 | ||
a5c9ffdb | 132 | void |
d8ee838b | 133 | kex_finish(Kex *kex) |
a5c9ffdb | 134 | { |
9d726f16 | 135 | kex_reset_dispatch(); |
d8ee838b | 136 | |
a5c9ffdb | 137 | packet_start(SSH2_MSG_NEWKEYS); |
138 | packet_send(); | |
139 | /* packet_write_wait(); */ | |
140 | debug("SSH2_MSG_NEWKEYS sent"); | |
4f8c6159 | 141 | |
a77673cc | 142 | debug("expecting SSH2_MSG_NEWKEYS"); |
54a5250f | 143 | packet_read_expect(SSH2_MSG_NEWKEYS); |
b967d870 | 144 | packet_check_eom(); |
a5c9ffdb | 145 | debug("SSH2_MSG_NEWKEYS received"); |
a7ca6275 | 146 | |
c422989b | 147 | kex->done = 1; |
a5c9ffdb | 148 | buffer_clear(&kex->peer); |
d1ac6175 | 149 | /* buffer_clear(&kex->my); */ |
a5c9ffdb | 150 | kex->flags &= ~KEX_INIT_SENT; |
a7ca6275 | 151 | xfree(kex->name); |
152 | kex->name = NULL; | |
4f8c6159 | 153 | } |
154 | ||
a5c9ffdb | 155 | void |
156 | kex_send_kexinit(Kex *kex) | |
94ec8c6b | 157 | { |
ca75d7de | 158 | u_int32_t rnd = 0; |
76bf34f1 | 159 | u_char *cookie; |
2ceb8101 | 160 | u_int i; |
76bf34f1 | 161 | |
7a37c112 | 162 | if (kex == NULL) { |
163 | error("kex_send_kexinit: no kex, cannot rekey"); | |
164 | return; | |
165 | } | |
d8ee838b | 166 | if (kex->flags & KEX_INIT_SENT) { |
167 | debug("KEX_INIT_SENT"); | |
168 | return; | |
169 | } | |
c422989b | 170 | kex->done = 0; |
76bf34f1 | 171 | |
172 | /* generate a random cookie */ | |
173 | if (buffer_len(&kex->my) < KEX_COOKIE_LEN) | |
174 | fatal("kex_send_kexinit: kex proposal too short"); | |
175 | cookie = buffer_ptr(&kex->my); | |
176 | for (i = 0; i < KEX_COOKIE_LEN; i++) { | |
177 | if (i % 4 == 0) | |
ca75d7de | 178 | rnd = arc4random(); |
179 | cookie[i] = rnd; | |
180 | rnd >>= 8; | |
76bf34f1 | 181 | } |
a5c9ffdb | 182 | packet_start(SSH2_MSG_KEXINIT); |
183 | packet_put_raw(buffer_ptr(&kex->my), buffer_len(&kex->my)); | |
184 | packet_send(); | |
185 | debug("SSH2_MSG_KEXINIT sent"); | |
186 | kex->flags |= KEX_INIT_SENT; | |
187 | } | |
2b87da3b | 188 | |
a5c9ffdb | 189 | void |
7819b5c3 | 190 | kex_input_kexinit(int type, u_int32_t seq, void *ctxt) |
a5c9ffdb | 191 | { |
192 | char *ptr; | |
2ceb8101 | 193 | u_int i, dlen; |
a5c9ffdb | 194 | Kex *kex = (Kex *)ctxt; |
94ec8c6b | 195 | |
a5c9ffdb | 196 | debug("SSH2_MSG_KEXINIT received"); |
7a37c112 | 197 | if (kex == NULL) |
198 | fatal("kex_input_kexinit: no kex, cannot rekey"); | |
94ec8c6b | 199 | |
a5c9ffdb | 200 | ptr = packet_get_raw(&dlen); |
201 | buffer_append(&kex->peer, ptr, dlen); | |
94ec8c6b | 202 | |
bbb4cc1b | 203 | /* discard packet */ |
204 | for (i = 0; i < KEX_COOKIE_LEN; i++) | |
205 | packet_get_char(); | |
206 | for (i = 0; i < PROPOSAL_MAX; i++) | |
207 | xfree(packet_get_string(NULL)); | |
1169c3df | 208 | (void) packet_get_char(); |
209 | (void) packet_get_int(); | |
95500969 | 210 | packet_check_eom(); |
bbb4cc1b | 211 | |
a5c9ffdb | 212 | kex_kexinit_finish(kex); |
94ec8c6b | 213 | } |
214 | ||
a5c9ffdb | 215 | Kex * |
d8ee838b | 216 | kex_setup(char *proposal[PROPOSAL_MAX]) |
4f8c6159 | 217 | { |
a5c9ffdb | 218 | Kex *kex; |
4f8c6159 | 219 | |
52e3daed | 220 | kex = xcalloc(1, sizeof(*kex)); |
a5c9ffdb | 221 | buffer_init(&kex->peer); |
222 | buffer_init(&kex->my); | |
223 | kex_prop2buf(&kex->my, proposal); | |
c422989b | 224 | kex->done = 0; |
a5c9ffdb | 225 | |
226 | kex_send_kexinit(kex); /* we start */ | |
9d726f16 | 227 | kex_reset_dispatch(); |
7a37c112 | 228 | |
a5c9ffdb | 229 | return kex; |
230 | } | |
4f8c6159 | 231 | |
396c147e | 232 | static void |
a5c9ffdb | 233 | kex_kexinit_finish(Kex *kex) |
234 | { | |
235 | if (!(kex->flags & KEX_INIT_SENT)) | |
236 | kex_send_kexinit(kex); | |
237 | ||
238 | kex_choose_conf(kex); | |
239 | ||
98a58eda | 240 | if (kex->kex_type >= 0 && kex->kex_type < KEX_MAX && |
241 | kex->kex[kex->kex_type] != NULL) { | |
242 | (kex->kex[kex->kex_type])(kex); | |
243 | } else { | |
a5c9ffdb | 244 | fatal("Unsupported key exchange %d", kex->kex_type); |
4f8c6159 | 245 | } |
4f8c6159 | 246 | } |
247 | ||
396c147e | 248 | static void |
4f8c6159 | 249 | choose_enc(Enc *enc, char *client, char *server) |
250 | { | |
cab80f75 | 251 | char *name = match_list(client, server, NULL); |
4f8c6159 | 252 | if (name == NULL) |
253 | fatal("no matching cipher found: client %s server %s", client, server); | |
3ee832e5 | 254 | if ((enc->cipher = cipher_by_name(name)) == NULL) |
94ec8c6b | 255 | fatal("matching cipher is not supported: %s", name); |
4f8c6159 | 256 | enc->name = name; |
257 | enc->enabled = 0; | |
258 | enc->iv = NULL; | |
259 | enc->key = NULL; | |
3ee832e5 | 260 | enc->key_len = cipher_keylen(enc->cipher); |
261 | enc->block_size = cipher_blocksize(enc->cipher); | |
4f8c6159 | 262 | } |
a7137f6b | 263 | |
396c147e | 264 | static void |
4f8c6159 | 265 | choose_mac(Mac *mac, char *client, char *server) |
266 | { | |
cab80f75 | 267 | char *name = match_list(client, server, NULL); |
4f8c6159 | 268 | if (name == NULL) |
269 | fatal("no matching mac found: client %s server %s", client, server); | |
b2552997 | 270 | if (mac_init(mac, name) < 0) |
4f8c6159 | 271 | fatal("unsupported mac %s", name); |
b2552997 | 272 | /* truncate the key */ |
273 | if (datafellows & SSH_BUG_HMAC) | |
274 | mac->key_len = 16; | |
4f8c6159 | 275 | mac->name = name; |
4f8c6159 | 276 | mac->key = NULL; |
277 | mac->enabled = 0; | |
278 | } | |
a7137f6b | 279 | |
396c147e | 280 | static void |
4f8c6159 | 281 | choose_comp(Comp *comp, char *client, char *server) |
282 | { | |
cab80f75 | 283 | char *name = match_list(client, server, NULL); |
4f8c6159 | 284 | if (name == NULL) |
285 | fatal("no matching comp found: client %s server %s", client, server); | |
07200973 | 286 | if (strcmp(name, "zlib@openssh.com") == 0) { |
287 | comp->type = COMP_DELAYED; | |
288 | } else if (strcmp(name, "zlib") == 0) { | |
289 | comp->type = COMP_ZLIB; | |
4f8c6159 | 290 | } else if (strcmp(name, "none") == 0) { |
07200973 | 291 | comp->type = COMP_NONE; |
4f8c6159 | 292 | } else { |
293 | fatal("unsupported comp %s", name); | |
294 | } | |
295 | comp->name = name; | |
296 | } | |
a7137f6b | 297 | |
396c147e | 298 | static void |
4f8c6159 | 299 | choose_kex(Kex *k, char *client, char *server) |
300 | { | |
cab80f75 | 301 | k->name = match_list(client, server, NULL); |
4f8c6159 | 302 | if (k->name == NULL) |
303 | fatal("no kex alg"); | |
94ec8c6b | 304 | if (strcmp(k->name, KEX_DH1) == 0) { |
98a58eda | 305 | k->kex_type = KEX_DH_GRP1_SHA1; |
47e5dc72 | 306 | k->evp_md = EVP_sha1(); |
41e5bd9a | 307 | } else if (strcmp(k->name, KEX_DH14) == 0) { |
308 | k->kex_type = KEX_DH_GRP14_SHA1; | |
47e5dc72 | 309 | k->evp_md = EVP_sha1(); |
310 | } else if (strcmp(k->name, KEX_DHGEX_SHA1) == 0) { | |
98a58eda | 311 | k->kex_type = KEX_DH_GEX_SHA1; |
47e5dc72 | 312 | k->evp_md = EVP_sha1(); |
30baf904 | 313 | #if OPENSSL_VERSION_NUMBER >= 0x00907000L |
2ff8003a | 314 | } else if (strcmp(k->name, KEX_DHGEX_SHA256) == 0) { |
315 | k->kex_type = KEX_DH_GEX_SHA256; | |
316 | k->evp_md = evp_ssh_sha256(); | |
30baf904 | 317 | #endif |
94ec8c6b | 318 | } else |
4f8c6159 | 319 | fatal("bad kex alg %s", k->name); |
320 | } | |
47e5dc72 | 321 | |
396c147e | 322 | static void |
4f8c6159 | 323 | choose_hostkeyalg(Kex *k, char *client, char *server) |
324 | { | |
cab80f75 | 325 | char *hostkeyalg = match_list(client, server, NULL); |
fa08c86b | 326 | if (hostkeyalg == NULL) |
4f8c6159 | 327 | fatal("no hostkey alg"); |
fa08c86b | 328 | k->hostkey_type = key_type_from_name(hostkeyalg); |
329 | if (k->hostkey_type == KEY_UNSPEC) | |
330 | fatal("bad hostkey alg '%s'", hostkeyalg); | |
eea39c02 | 331 | xfree(hostkeyalg); |
4f8c6159 | 332 | } |
333 | ||
aff51935 | 334 | static int |
eed8e583 | 335 | proposals_match(char *my[PROPOSAL_MAX], char *peer[PROPOSAL_MAX]) |
336 | { | |
337 | static int check[] = { | |
338 | PROPOSAL_KEX_ALGS, PROPOSAL_SERVER_HOST_KEY_ALGS, -1 | |
339 | }; | |
340 | int *idx; | |
341 | char *p; | |
342 | ||
343 | for (idx = &check[0]; *idx != -1; idx++) { | |
344 | if ((p = strchr(my[*idx], ',')) != NULL) | |
345 | *p = '\0'; | |
346 | if ((p = strchr(peer[*idx], ',')) != NULL) | |
347 | *p = '\0'; | |
348 | if (strcmp(my[*idx], peer[*idx]) != 0) { | |
349 | debug2("proposal mismatch: my %s peer %s", | |
350 | my[*idx], peer[*idx]); | |
351 | return (0); | |
352 | } | |
353 | } | |
354 | debug2("proposals match"); | |
355 | return (1); | |
356 | } | |
357 | ||
396c147e | 358 | static void |
d1ac6175 | 359 | kex_choose_conf(Kex *kex) |
4f8c6159 | 360 | { |
d1ac6175 | 361 | Newkeys *newkeys; |
a5c9ffdb | 362 | char **my, **peer; |
363 | char **cprop, **sprop; | |
d1ac6175 | 364 | int nenc, nmac, ncomp; |
2ceb8101 | 365 | u_int mode, ctos, need; |
eed8e583 | 366 | int first_kex_follows, type; |
4f8c6159 | 367 | |
eed8e583 | 368 | my = kex_buf2prop(&kex->my, NULL); |
369 | peer = kex_buf2prop(&kex->peer, &first_kex_follows); | |
a5c9ffdb | 370 | |
d1ac6175 | 371 | if (kex->server) { |
a5c9ffdb | 372 | cprop=peer; |
373 | sprop=my; | |
374 | } else { | |
375 | cprop=my; | |
376 | sprop=peer; | |
377 | } | |
4f8c6159 | 378 | |
c422989b | 379 | /* Algorithm Negotiation */ |
4f8c6159 | 380 | for (mode = 0; mode < MODE_MAX; mode++) { |
52e3daed | 381 | newkeys = xcalloc(1, sizeof(*newkeys)); |
c422989b | 382 | kex->newkeys[mode] = newkeys; |
d1ac6175 | 383 | ctos = (!kex->server && mode == MODE_OUT) || (kex->server && mode == MODE_IN); |
4f8c6159 | 384 | nenc = ctos ? PROPOSAL_ENC_ALGS_CTOS : PROPOSAL_ENC_ALGS_STOC; |
385 | nmac = ctos ? PROPOSAL_MAC_ALGS_CTOS : PROPOSAL_MAC_ALGS_STOC; | |
386 | ncomp = ctos ? PROPOSAL_COMP_ALGS_CTOS : PROPOSAL_COMP_ALGS_STOC; | |
d1ac6175 | 387 | choose_enc (&newkeys->enc, cprop[nenc], sprop[nenc]); |
388 | choose_mac (&newkeys->mac, cprop[nmac], sprop[nmac]); | |
389 | choose_comp(&newkeys->comp, cprop[ncomp], sprop[ncomp]); | |
4f8c6159 | 390 | debug("kex: %s %s %s %s", |
391 | ctos ? "client->server" : "server->client", | |
d1ac6175 | 392 | newkeys->enc.name, |
393 | newkeys->mac.name, | |
394 | newkeys->comp.name); | |
4f8c6159 | 395 | } |
d1ac6175 | 396 | choose_kex(kex, cprop[PROPOSAL_KEX_ALGS], sprop[PROPOSAL_KEX_ALGS]); |
397 | choose_hostkeyalg(kex, cprop[PROPOSAL_SERVER_HOST_KEY_ALGS], | |
4f8c6159 | 398 | sprop[PROPOSAL_SERVER_HOST_KEY_ALGS]); |
4f8c6159 | 399 | need = 0; |
400 | for (mode = 0; mode < MODE_MAX; mode++) { | |
c422989b | 401 | newkeys = kex->newkeys[mode]; |
3ee832e5 | 402 | if (need < newkeys->enc.key_len) |
403 | need = newkeys->enc.key_len; | |
404 | if (need < newkeys->enc.block_size) | |
405 | need = newkeys->enc.block_size; | |
d1ac6175 | 406 | if (need < newkeys->mac.key_len) |
407 | need = newkeys->mac.key_len; | |
4f8c6159 | 408 | } |
71276795 | 409 | /* XXX need runden? */ |
d1ac6175 | 410 | kex->we_need = need; |
a5c9ffdb | 411 | |
eed8e583 | 412 | /* ignore the next message if the proposals do not match */ |
aff51935 | 413 | if (first_kex_follows && !proposals_match(my, peer) && |
4e2e5cfd | 414 | !(datafellows & SSH_BUG_FIRSTKEX)) { |
eed8e583 | 415 | type = packet_read(); |
416 | debug2("skipping next packet (type %u)", type); | |
417 | } | |
418 | ||
a5c9ffdb | 419 | kex_prop_free(my); |
420 | kex_prop_free(peer); | |
a5c9ffdb | 421 | } |
422 | ||
396c147e | 423 | static u_char * |
47e5dc72 | 424 | derive_key(Kex *kex, int id, u_int need, u_char *hash, u_int hashlen, |
425 | BIGNUM *shared_secret) | |
a5c9ffdb | 426 | { |
427 | Buffer b; | |
a5c9ffdb | 428 | EVP_MD_CTX md; |
429 | char c = id; | |
2ceb8101 | 430 | u_int have; |
47e5dc72 | 431 | int mdsz; |
2ceb8101 | 432 | u_char *digest; |
56964485 | 433 | |
47e5dc72 | 434 | if ((mdsz = EVP_MD_size(kex->evp_md)) <= 0) |
435 | fatal("bad kex md size %d", mdsz); | |
b4bbf172 | 436 | digest = xmalloc(roundup(need, mdsz)); |
a5c9ffdb | 437 | |
438 | buffer_init(&b); | |
439 | buffer_put_bignum2(&b, shared_secret); | |
440 | ||
c422989b | 441 | /* K1 = HASH(K || H || "A" || session_id) */ |
47e5dc72 | 442 | EVP_DigestInit(&md, kex->evp_md); |
eef7adcb | 443 | if (!(datafellows & SSH_BUG_DERIVEKEY)) |
444 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
47e5dc72 | 445 | EVP_DigestUpdate(&md, hash, hashlen); |
c422989b | 446 | EVP_DigestUpdate(&md, &c, 1); |
d1ac6175 | 447 | EVP_DigestUpdate(&md, kex->session_id, kex->session_id_len); |
a5c9ffdb | 448 | EVP_DigestFinal(&md, digest, NULL); |
449 | ||
c422989b | 450 | /* |
451 | * expand key: | |
452 | * Kn = HASH(K || H || K1 || K2 || ... || Kn-1) | |
453 | * Key = K1 || K2 || ... || Kn | |
454 | */ | |
a5c9ffdb | 455 | for (have = mdsz; need > have; have += mdsz) { |
47e5dc72 | 456 | EVP_DigestInit(&md, kex->evp_md); |
eef7adcb | 457 | if (!(datafellows & SSH_BUG_DERIVEKEY)) |
458 | EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b)); | |
47e5dc72 | 459 | EVP_DigestUpdate(&md, hash, hashlen); |
a5c9ffdb | 460 | EVP_DigestUpdate(&md, digest, have); |
461 | EVP_DigestFinal(&md, digest + have, NULL); | |
462 | } | |
463 | buffer_free(&b); | |
464 | #ifdef DEBUG_KEX | |
465 | fprintf(stderr, "key '%c'== ", c); | |
466 | dump_digest("key", digest, need); | |
467 | #endif | |
468 | return digest; | |
4f8c6159 | 469 | } |
470 | ||
c422989b | 471 | Newkeys *current_keys[MODE_MAX]; |
d1ac6175 | 472 | |
cab80f75 | 473 | #define NKEYS 6 |
a5c9ffdb | 474 | void |
47e5dc72 | 475 | kex_derive_keys(Kex *kex, u_char *hash, u_int hashlen, BIGNUM *shared_secret) |
4f8c6159 | 476 | { |
1e3b8b07 | 477 | u_char *keys[NKEYS]; |
2ceb8101 | 478 | u_int i, mode, ctos; |
4f8c6159 | 479 | |
47e5dc72 | 480 | for (i = 0; i < NKEYS; i++) { |
481 | keys[i] = derive_key(kex, 'A'+i, kex->we_need, hash, hashlen, | |
482 | shared_secret); | |
483 | } | |
4f8c6159 | 484 | |
a77673cc | 485 | debug2("kex_derive_keys"); |
4f8c6159 | 486 | for (mode = 0; mode < MODE_MAX; mode++) { |
c422989b | 487 | current_keys[mode] = kex->newkeys[mode]; |
488 | kex->newkeys[mode] = NULL; | |
a7137f6b | 489 | ctos = (!kex->server && mode == MODE_OUT) || |
490 | (kex->server && mode == MODE_IN); | |
c422989b | 491 | current_keys[mode]->enc.iv = keys[ctos ? 0 : 1]; |
492 | current_keys[mode]->enc.key = keys[ctos ? 2 : 3]; | |
493 | current_keys[mode]->mac.key = keys[ctos ? 4 : 5]; | |
4f8c6159 | 494 | } |
4f8c6159 | 495 | } |
a5c9ffdb | 496 | |
d1ac6175 | 497 | Newkeys * |
498 | kex_get_newkeys(int mode) | |
499 | { | |
c422989b | 500 | Newkeys *ret; |
501 | ||
502 | ret = current_keys[mode]; | |
503 | current_keys[mode] = NULL; | |
504 | return ret; | |
d1ac6175 | 505 | } |
506 | ||
8bbf1fa6 | 507 | void |
508 | derive_ssh1_session_id(BIGNUM *host_modulus, BIGNUM *server_modulus, | |
509 | u_int8_t cookie[8], u_int8_t id[16]) | |
510 | { | |
511 | const EVP_MD *evp_md = EVP_md5(); | |
512 | EVP_MD_CTX md; | |
513 | u_int8_t nbuf[2048], obuf[EVP_MAX_MD_SIZE]; | |
514 | int len; | |
515 | ||
516 | EVP_DigestInit(&md, evp_md); | |
517 | ||
518 | len = BN_num_bytes(host_modulus); | |
2ceb8101 | 519 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) |
8bbf1fa6 | 520 | fatal("%s: bad host modulus (len %d)", __func__, len); |
521 | BN_bn2bin(host_modulus, nbuf); | |
522 | EVP_DigestUpdate(&md, nbuf, len); | |
523 | ||
524 | len = BN_num_bytes(server_modulus); | |
2ceb8101 | 525 | if (len < (512 / 8) || (u_int)len > sizeof(nbuf)) |
8bbf1fa6 | 526 | fatal("%s: bad server modulus (len %d)", __func__, len); |
527 | BN_bn2bin(server_modulus, nbuf); | |
528 | EVP_DigestUpdate(&md, nbuf, len); | |
529 | ||
530 | EVP_DigestUpdate(&md, cookie, 8); | |
531 | ||
59657003 | 532 | EVP_DigestFinal(&md, obuf, NULL); |
8bbf1fa6 | 533 | memcpy(id, obuf, 16); |
534 | ||
535 | memset(nbuf, 0, sizeof(nbuf)); | |
536 | memset(obuf, 0, sizeof(obuf)); | |
537 | memset(&md, 0, sizeof(md)); | |
538 | } | |
539 | ||
a5c9ffdb | 540 | #if defined(DEBUG_KEX) || defined(DEBUG_KEXDH) |
541 | void | |
542 | dump_digest(char *msg, u_char *digest, int len) | |
543 | { | |
2ceb8101 | 544 | u_int i; |
a5c9ffdb | 545 | |
546 | fprintf(stderr, "%s\n", msg); | |
6aacefa7 | 547 | for (i = 0; i< len; i++) { |
a5c9ffdb | 548 | fprintf(stderr, "%02x", digest[i]); |
549 | if (i%32 == 31) | |
550 | fprintf(stderr, "\n"); | |
551 | else if (i%8 == 7) | |
552 | fprintf(stderr, " "); | |
553 | } | |
554 | fprintf(stderr, "\n"); | |
555 | } | |
556 | #endif |