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Makefile.in contains updated files required
author Matt Johnston <matt@ucc.asn.au>
date Tue, 01 Jun 2004 02:46:09 +0000
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children c1e5d9195402
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1 /*
2 * Dropbear - a SSH2 server
3 * SSH client implementation
4 *
5 * This code is copied from the larger file "kex.c"
6 * some functions are verbatim, others are generalized --mihnea
7 *
8 * Copyright (c) 2002,2003 Matt Johnston
9 * Portions Copyright (c) 2004 by Mihnea Stoenescu
10 * All rights reserved.
11 *
12 * Permission is hereby granted, free of charge, to any person obtaining a copy
13 * of this software and associated documentation files (the "Software"), to deal
14 * in the Software without restriction, including without limitation the rights
15 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
16 * copies of the Software, and to permit persons to whom the Software is
17 * furnished to do so, subject to the following conditions:
18 *
19 * The above copyright notice and this permission notice shall be included in
20 * all copies or substantial portions of the Software.
21 *
22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
25 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
26 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
27 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
28 * SOFTWARE. */
29
30 #include "includes.h"
31 #include "dbutil.h"
32 #include "algo.h"
33 #include "buffer.h"
34 #include "session.h"
35 #include "kex.h"
36 #include "ssh.h"
37 #include "packet.h"
38 #include "bignum.h"
39 #include "random.h"
40
41 /* diffie-hellman-group1-sha1 value for p */
42 const unsigned char dh_p_val[] = {
43 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
44 0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
45 0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
46 0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
47 0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
48 0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
49 0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
50 0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
51 0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
52 0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE6, 0x53, 0x81,
53 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
54
55 const int DH_G_VAL = 2;
56
57 static void gen_new_keys();
58 #ifndef DISABLE_ZLIB
59 static void gen_new_zstreams();
60 #endif
61 /* helper function for gen_new_keys */
62 static void hashkeys(unsigned char *out, int outlen,
63 const hash_state * hs, unsigned const char X);
64
65
66 /* Send our list of algorithms we can use */
67 void send_msg_kexinit() {
68
69 CHECKCLEARTOWRITE();
70 buf_putbyte(ses.writepayload, SSH_MSG_KEXINIT);
71
72 /* cookie */
73 genrandom(buf_getwriteptr(ses.writepayload, 16), 16);
74 buf_incrwritepos(ses.writepayload, 16);
75
76 /* kex algos */
77 buf_put_algolist(ses.writepayload, sshkex);
78
79 /* server_host_key_algorithms */
80 buf_put_algolist(ses.writepayload, sshhostkey);
81
82 /* encryption_algorithms_client_to_server */
83 buf_put_algolist(ses.writepayload, sshciphers);
84
85 /* encryption_algorithms_server_to_client */
86 buf_put_algolist(ses.writepayload, sshciphers);
87
88 /* mac_algorithms_client_to_server */
89 buf_put_algolist(ses.writepayload, sshhashes);
90
91 /* mac_algorithms_server_to_client */
92 buf_put_algolist(ses.writepayload, sshhashes);
93
94 /* compression_algorithms_client_to_server */
95 buf_put_algolist(ses.writepayload, sshcompress);
96
97 /* compression_algorithms_server_to_client */
98 buf_put_algolist(ses.writepayload, sshcompress);
99
100 /* languages_client_to_server */
101 buf_putstring(ses.writepayload, "", 0);
102
103 /* languages_server_to_client */
104 buf_putstring(ses.writepayload, "", 0);
105
106 /* first_kex_packet_follows - unimplemented for now */
107 buf_putbyte(ses.writepayload, 0x00);
108
109 /* reserved unit32 */
110 buf_putint(ses.writepayload, 0);
111
112 /* set up transmitted kex packet buffer for hashing.
113 * This is freed after the end of the kex */
114 ses.transkexinit = buf_newcopy(ses.writepayload);
115
116 encrypt_packet();
117 ses.dataallowed = 0; /* don't send other packets during kex */
118
119 TRACE(("DATAALLOWED=0"));
120 TRACE(("-> KEXINIT"));
121 ses.kexstate.sentkexinit = 1;
122 }
123
124 /* *** NOTE regarding (send|recv)_msg_newkeys ***
125 * Changed by mihnea from the original kex.c to set dataallowed after a
126 * completed key exchange, no matter the order in which it was performed.
127 * This enables client mode without affecting server functionality.
128 */
129
130 /* Bring new keys into use after a key exchange, and let the client know*/
131 void send_msg_newkeys() {
132
133 TRACE(("enter send_msg_newkeys"));
134
135 /* generate the kexinit request */
136 CHECKCLEARTOWRITE();
137 buf_putbyte(ses.writepayload, SSH_MSG_NEWKEYS);
138 encrypt_packet();
139
140
141 /* set up our state */
142 if (ses.kexstate.recvnewkeys) {
143 TRACE(("while RECVNEWKEYS=1"));
144 gen_new_keys();
145 kexinitialise(); /* we've finished with this kex */
146 TRACE((" -> DATAALLOWED=1"));
147 ses.dataallowed = 1; /* we can send other packets again now */
148 } else {
149 ses.kexstate.sentnewkeys = 1;
150 TRACE(("SENTNEWKEYS=1"));
151 }
152
153 TRACE(("-> MSG_NEWKEYS"));
154 TRACE(("leave send_msg_newkeys"));
155 }
156
157 /* Bring the new keys into use after a key exchange */
158 void recv_msg_newkeys() {
159
160 TRACE(("<- MSG_NEWKEYS"));
161 TRACE(("enter recv_msg_newkeys"));
162
163 /* simply check if we've sent SSH_MSG_NEWKEYS, and if so,
164 * switch to the new keys */
165 if (ses.kexstate.sentnewkeys) {
166 TRACE(("while SENTNEWKEYS=1"));
167 gen_new_keys();
168 kexinitialise(); /* we've finished with this kex */
169 TRACE((" -> DATAALLOWED=1"));
170 ses.dataallowed = 1; /* we can send other packets again now */
171 } else {
172 TRACE(("RECVNEWKEYS=1"));
173 ses.kexstate.recvnewkeys = 1;
174 }
175
176 TRACE(("leave recv_msg_newkeys"));
177 }
178
179
180 /* Duplicated verbatim from kex.c --mihnea */
181 void kexinitialise() {
182
183 struct timeval tv;
184
185 TRACE(("kexinitialise()"));
186
187 /* sent/recv'd MSG_KEXINIT */
188 ses.kexstate.sentkexinit = 0;
189 ses.kexstate.recvkexinit = 0;
190
191 /* sent/recv'd MSG_NEWKEYS */
192 ses.kexstate.recvnewkeys = 0;
193 ses.kexstate.sentnewkeys = 0;
194
195 /* first_packet_follows */
196 /* TODO - currently not handled */
197 ses.kexstate.firstfollows = 0;
198
199 ses.kexstate.datatrans = 0;
200 ses.kexstate.datarecv = 0;
201
202 if (gettimeofday(&tv, 0) < 0) {
203 dropbear_exit("Error getting time");
204 }
205 ses.kexstate.lastkextime = tv.tv_sec;
206
207 }
208
209 /* Helper function for gen_new_keys, creates a hash. It makes a copy of the
210 * already initialised hash_state hs, which should already have processed
211 * the dh_K and hash, since these are common. X is the letter 'A', 'B' etc.
212 * out must have at least min(SHA1_HASH_SIZE, outlen) bytes allocated.
213 * The output will only be expanded once, since that is all that is required
214 * (for 3DES and SHA, with 24 and 20 bytes respectively).
215 *
216 * See Section 5.2 of the IETF secsh Transport Draft for details */
217
218 /* Duplicated verbatim from kex.c --mihnea */
219 static void hashkeys(unsigned char *out, int outlen,
220 const hash_state * hs, const unsigned char X) {
221
222 hash_state hs2;
223 unsigned char k2[SHA1_HASH_SIZE]; /* used to extending */
224
225 memcpy(&hs2, hs, sizeof(hash_state));
226 sha1_process(&hs2, &X, 1);
227 sha1_process(&hs2, ses.session_id, SHA1_HASH_SIZE);
228 sha1_done(&hs2, out);
229 if (SHA1_HASH_SIZE < outlen) {
230 /* need to extend */
231 memcpy(&hs2, hs, sizeof(hash_state));
232 sha1_process(&hs2, out, SHA1_HASH_SIZE);
233 sha1_done(&hs2, k2);
234 memcpy(&out[SHA1_HASH_SIZE], k2, outlen - SHA1_HASH_SIZE);
235 }
236 }
237
238 /* Generate the actual encryption/integrity keys, using the results of the
239 * key exchange, as specified in section 5.2 of the IETF secsh-transport
240 * draft. This occurs after the DH key-exchange.
241 *
242 * ses.newkeys is the new set of keys which are generated, these are only
243 * taken into use after both sides have sent a newkeys message */
244
245 /* Originally from kex.c, generalized for cli/svr mode --mihnea */
246 static void gen_new_keys() {
247
248 unsigned char C2S_IV[MAX_IV_LEN];
249 unsigned char C2S_key[MAX_KEY_LEN];
250 unsigned char S2C_IV[MAX_IV_LEN];
251 unsigned char S2C_key[MAX_KEY_LEN];
252 /* unsigned char key[MAX_KEY_LEN]; */
253 unsigned char *trans_IV, *trans_key, *recv_IV, *recv_key;
254
255 hash_state hs;
256 unsigned int C2S_keysize, S2C_keysize;
257 char mactransletter, macrecvletter; /* Client or server specific */
258
259 TRACE(("enter gen_new_keys"));
260 /* the dh_K and hash are the start of all hashes, we make use of that */
261
262 sha1_init(&hs);
263 sha1_process_mp(&hs, ses.dh_K);
264 mp_clear(ses.dh_K);
265 m_free(ses.dh_K);
266 sha1_process(&hs, ses.hash, SHA1_HASH_SIZE);
267 m_burn(ses.hash, SHA1_HASH_SIZE);
268
269 hashkeys(C2S_IV, SHA1_HASH_SIZE, &hs, 'A');
270 hashkeys(S2C_IV, SHA1_HASH_SIZE, &hs, 'B');
271
272 if (IS_DROPBEAR_CLIENT) {
273 trans_IV = C2S_IV;
274 recv_IV = S2C_IV;
275 trans_key = C2S_key;
276 recv_key = S2C_key;
277 C2S_keysize = ses.newkeys->trans_algo_crypt->keysize;
278 S2C_keysize = ses.newkeys->recv_algo_crypt->keysize;
279 mactransletter = 'E';
280 macrecvletter = 'F';
281 } else {
282 trans_IV = S2C_IV;
283 recv_IV = C2S_IV;
284 trans_key = S2C_key;
285 recv_key = C2S_key;
286 C2S_keysize = ses.newkeys->recv_algo_crypt->keysize;
287 S2C_keysize = ses.newkeys->trans_algo_crypt->keysize;
288 mactransletter = 'F';
289 macrecvletter = 'E';
290 }
291
292 hashkeys(C2S_key, C2S_keysize, &hs, 'C');
293 hashkeys(S2C_key, S2C_keysize, &hs, 'D');
294
295 if (cbc_start(
296 find_cipher(ses.newkeys->recv_algo_crypt->cipherdesc->name),
297 recv_IV, recv_key,
298 ses.newkeys->recv_algo_crypt->keysize, 0,
299 &ses.newkeys->recv_symmetric_struct) != CRYPT_OK) {
300 dropbear_exit("crypto error");
301 }
302
303 if (cbc_start(
304 find_cipher(ses.newkeys->trans_algo_crypt->cipherdesc->name),
305 trans_IV, trans_key,
306 ses.newkeys->trans_algo_crypt->keysize, 0,
307 &ses.newkeys->trans_symmetric_struct) != CRYPT_OK) {
308 dropbear_exit("crypto error");
309 }
310
311 /* MAC keys */
312 hashkeys(ses.newkeys->transmackey,
313 ses.newkeys->trans_algo_mac->keysize, &hs, mactransletter);
314 hashkeys(ses.newkeys->recvmackey,
315 ses.newkeys->recv_algo_mac->keysize, &hs, macrecvletter);
316
317 #ifndef DISABLE_ZLIB
318 gen_new_zstreams();
319 #endif
320
321 /* Switch over to the new keys */
322 m_burn(ses.keys, sizeof(struct key_context));
323 m_free(ses.keys);
324 ses.keys = ses.newkeys;
325 ses.newkeys = NULL;
326
327 TRACE(("leave gen_new_keys"));
328 }
329
330 #ifndef DISABLE_ZLIB
331 /* Set up new zlib compression streams, close the old ones. Only
332 * called from gen_new_keys() */
333 static void gen_new_zstreams() {
334
335 /* create new zstreams */
336 if (ses.newkeys->recv_algo_comp == DROPBEAR_COMP_ZLIB) {
337 ses.newkeys->recv_zstream = (z_streamp)m_malloc(sizeof(z_stream));
338 ses.newkeys->recv_zstream->zalloc = Z_NULL;
339 ses.newkeys->recv_zstream->zfree = Z_NULL;
340
341 if (inflateInit(ses.newkeys->recv_zstream) != Z_OK) {
342 dropbear_exit("zlib error");
343 }
344 } else {
345 ses.newkeys->recv_zstream = NULL;
346 }
347
348 if (ses.newkeys->trans_algo_comp == DROPBEAR_COMP_ZLIB) {
349 ses.newkeys->trans_zstream = (z_streamp)m_malloc(sizeof(z_stream));
350 ses.newkeys->trans_zstream->zalloc = Z_NULL;
351 ses.newkeys->trans_zstream->zfree = Z_NULL;
352
353 if (deflateInit(ses.newkeys->trans_zstream, Z_DEFAULT_COMPRESSION)
354 != Z_OK) {
355 dropbear_exit("zlib error");
356 }
357 } else {
358 ses.newkeys->trans_zstream = NULL;
359 }
360
361 /* clean up old keys */
362 if (ses.keys->recv_zstream != NULL) {
363 if (inflateEnd(ses.keys->recv_zstream) == Z_STREAM_ERROR) {
364 /* Z_DATA_ERROR is ok, just means that stream isn't ended */
365 dropbear_exit("crypto error");
366 }
367 m_free(ses.keys->recv_zstream);
368 }
369 if (ses.keys->trans_zstream != NULL) {
370 if (deflateEnd(ses.keys->trans_zstream) == Z_STREAM_ERROR) {
371 /* Z_DATA_ERROR is ok, just means that stream isn't ended */
372 dropbear_exit("crypto error");
373 }
374 m_free(ses.keys->trans_zstream);
375 }
376 }
377 #endif
378
379
380 /* Executed upon receiving a kexinit message from the client to initiate
381 * key exchange. If we haven't already done so, we send the list of our
382 * preferred algorithms. The client's requested algorithms are processed,
383 * and we calculate the first portion of the key-exchange-hash for used
384 * later in the key exchange. No response is sent, as the client should
385 * initiate the diffie-hellman key exchange */
386
387 /* Originally from kex.c, generalized for cli/svr mode --mihnea */
388 /* Belongs in common_kex.c where it should be moved after review */
389 void recv_msg_kexinit() {
390
391 TRACE(("<- KEXINIT"));
392 TRACE(("enter recv_msg_kexinit"));
393
394 /* start the kex hash */
395 ses.kexhashbuf = buf_new(MAX_KEXHASHBUF);
396
397 if (!ses.kexstate.sentkexinit) {
398 /* we need to send a kex packet */
399 send_msg_kexinit();
400 TRACE(("continue recv_msg_kexinit: sent kexinit"));
401 }
402
403
404 if (IS_DROPBEAR_CLIENT) {
405
406 /* read the peer's choice of algos */
407 cli_read_kex();
408
409 /* V_C, the client's version string (CR and NL excluded) */
410 buf_putstring(ses.kexhashbuf,
411 (unsigned char*)LOCAL_IDENT, strlen(LOCAL_IDENT));
412 /* V_S, the server's version string (CR and NL excluded) */
413 buf_putstring(ses.kexhashbuf,
414 ses.remoteident, strlen((char*)ses.remoteident));
415
416 /* I_C, the payload of the client's SSH_MSG_KEXINIT */
417 buf_putstring(ses.kexhashbuf,
418 buf_getptr(ses.transkexinit, ses.transkexinit->len),
419 ses.transkexinit->len);
420 /* I_S, the payload of the server's SSH_MSG_KEXINIT */
421 buf_setpos(ses.payload, 0);
422 buf_putstring(ses.kexhashbuf,
423 buf_getptr(ses.payload, ses.payload->len),
424 ses.payload->len);
425
426 } else {
427
428 /* read the peer's choice of algos */
429 svr_read_kex();
430 /* V_C, the client's version string (CR and NL excluded) */
431 buf_putstring(ses.kexhashbuf,
432 ses.remoteident, strlen((char*)ses.remoteident));
433 /* V_S, the server's version string (CR and NL excluded) */
434 buf_putstring(ses.kexhashbuf,
435 (unsigned char*)LOCAL_IDENT, strlen(LOCAL_IDENT));
436
437 /* I_C, the payload of the client's SSH_MSG_KEXINIT */
438 buf_setpos(ses.payload, 0);
439 buf_putstring(ses.kexhashbuf,
440 buf_getptr(ses.payload, ses.payload->len),
441 ses.payload->len);
442 /* I_S, the payload of the server's SSH_MSG_KEXINIT */
443 buf_putstring(ses.kexhashbuf,
444 buf_getptr(ses.transkexinit, ses.transkexinit->len),
445 ses.transkexinit->len);
446 }
447
448 buf_free(ses.transkexinit);
449 ses.transkexinit = NULL;
450 /* the rest of ses.kexhashbuf will be done after DH exchange */
451
452 ses.kexstate.recvkexinit = 1;
453 // ses.expecting = SSH_MSG_KEXDH_INIT;
454 ses.expecting = 0;
455
456 TRACE(("leave recv_msg_kexinit"));
457 }
458