dropbear: update to 2013.62
[tomato.git] / release / src / router / dropbear / common-kex.c
blob77a7aa69570088108790920cbf65ee1c8c8f047c
1 /*
2 * Dropbear SSH
3 *
4 * Copyright (c) 2002-2004 Matt Johnston
5 * Portions Copyright (c) 2004 by Mihnea Stoenescu
6 * All rights reserved.
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this software and associated documentation files (the "Software"), to deal
10 * in the Software without restriction, including without limitation the rights
11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12 * copies of the Software, and to permit persons to whom the Software is
13 * furnished to do so, subject to the following conditions:
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
24 * SOFTWARE. */
26 #include "includes.h"
27 #include "dbutil.h"
28 #include "algo.h"
29 #include "buffer.h"
30 #include "session.h"
31 #include "kex.h"
32 #include "ssh.h"
33 #include "packet.h"
34 #include "bignum.h"
35 #include "dbrandom.h"
36 #include "runopts.h"
37 #include "ecc.h"
38 #include "crypto_desc.h"
40 /* diffie-hellman-group1-sha1 value for p */
41 const unsigned char dh_p_1[DH_P_1_LEN] = {
42 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
43 0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
44 0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
45 0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
46 0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
47 0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
48 0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
49 0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
50 0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
51 0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE6, 0x53, 0x81,
52 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
54 /* diffie-hellman-group14-sha1 value for p */
55 const unsigned char dh_p_14[DH_P_14_LEN] = {
56 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xC9, 0x0F, 0xDA, 0xA2,
57 0x21, 0x68, 0xC2, 0x34, 0xC4, 0xC6, 0x62, 0x8B, 0x80, 0xDC, 0x1C, 0xD1,
58 0x29, 0x02, 0x4E, 0x08, 0x8A, 0x67, 0xCC, 0x74, 0x02, 0x0B, 0xBE, 0xA6,
59 0x3B, 0x13, 0x9B, 0x22, 0x51, 0x4A, 0x08, 0x79, 0x8E, 0x34, 0x04, 0xDD,
60 0xEF, 0x95, 0x19, 0xB3, 0xCD, 0x3A, 0x43, 0x1B, 0x30, 0x2B, 0x0A, 0x6D,
61 0xF2, 0x5F, 0x14, 0x37, 0x4F, 0xE1, 0x35, 0x6D, 0x6D, 0x51, 0xC2, 0x45,
62 0xE4, 0x85, 0xB5, 0x76, 0x62, 0x5E, 0x7E, 0xC6, 0xF4, 0x4C, 0x42, 0xE9,
63 0xA6, 0x37, 0xED, 0x6B, 0x0B, 0xFF, 0x5C, 0xB6, 0xF4, 0x06, 0xB7, 0xED,
64 0xEE, 0x38, 0x6B, 0xFB, 0x5A, 0x89, 0x9F, 0xA5, 0xAE, 0x9F, 0x24, 0x11,
65 0x7C, 0x4B, 0x1F, 0xE6, 0x49, 0x28, 0x66, 0x51, 0xEC, 0xE4, 0x5B, 0x3D,
66 0xC2, 0x00, 0x7C, 0xB8, 0xA1, 0x63, 0xBF, 0x05, 0x98, 0xDA, 0x48, 0x36,
67 0x1C, 0x55, 0xD3, 0x9A, 0x69, 0x16, 0x3F, 0xA8, 0xFD, 0x24, 0xCF, 0x5F,
68 0x83, 0x65, 0x5D, 0x23, 0xDC, 0xA3, 0xAD, 0x96, 0x1C, 0x62, 0xF3, 0x56,
69 0x20, 0x85, 0x52, 0xBB, 0x9E, 0xD5, 0x29, 0x07, 0x70, 0x96, 0x96, 0x6D,
70 0x67, 0x0C, 0x35, 0x4E, 0x4A, 0xBC, 0x98, 0x04, 0xF1, 0x74, 0x6C, 0x08,
71 0xCA, 0x18, 0x21, 0x7C, 0x32, 0x90, 0x5E, 0x46, 0x2E, 0x36, 0xCE, 0x3B,
72 0xE3, 0x9E, 0x77, 0x2C, 0x18, 0x0E, 0x86, 0x03, 0x9B, 0x27, 0x83, 0xA2,
73 0xEC, 0x07, 0xA2, 0x8F, 0xB5, 0xC5, 0x5D, 0xF0, 0x6F, 0x4C, 0x52, 0xC9,
74 0xDE, 0x2B, 0xCB, 0xF6, 0x95, 0x58, 0x17, 0x18, 0x39, 0x95, 0x49, 0x7C,
75 0xEA, 0x95, 0x6A, 0xE5, 0x15, 0xD2, 0x26, 0x18, 0x98, 0xFA, 0x05, 0x10,
76 0x15, 0x72, 0x8E, 0x5A, 0x8A, 0xAC, 0xAA, 0x68, 0xFF, 0xFF, 0xFF, 0xFF,
77 0xFF, 0xFF, 0xFF, 0xFF};
79 /* Same for group1 and group14 */
80 static const int DH_G_VAL = 2;
82 static void kexinitialise();
83 static void gen_new_keys();
84 #ifndef DISABLE_ZLIB
85 static void gen_new_zstream_recv();
86 static void gen_new_zstream_trans();
87 #endif
88 static void read_kex_algos();
89 /* helper function for gen_new_keys */
90 static void hashkeys(unsigned char *out, unsigned int outlen,
91 const hash_state * hs, const unsigned char X);
92 static void finish_kexhashbuf(void);
95 /* Send our list of algorithms we can use */
96 void send_msg_kexinit() {
98 CHECKCLEARTOWRITE();
99 buf_putbyte(ses.writepayload, SSH_MSG_KEXINIT);
101 /* cookie */
102 genrandom(buf_getwriteptr(ses.writepayload, 16), 16);
103 buf_incrwritepos(ses.writepayload, 16);
105 /* kex algos */
106 buf_put_algolist(ses.writepayload, sshkex);
108 /* server_host_key_algorithms */
109 buf_put_algolist(ses.writepayload, sshhostkey);
111 /* encryption_algorithms_client_to_server */
112 buf_put_algolist(ses.writepayload, sshciphers);
114 /* encryption_algorithms_server_to_client */
115 buf_put_algolist(ses.writepayload, sshciphers);
117 /* mac_algorithms_client_to_server */
118 buf_put_algolist(ses.writepayload, sshhashes);
120 /* mac_algorithms_server_to_client */
121 buf_put_algolist(ses.writepayload, sshhashes);
124 /* compression_algorithms_client_to_server */
125 buf_put_algolist(ses.writepayload, ses.compress_algos);
127 /* compression_algorithms_server_to_client */
128 buf_put_algolist(ses.writepayload, ses.compress_algos);
130 /* languages_client_to_server */
131 buf_putstring(ses.writepayload, "", 0);
133 /* languages_server_to_client */
134 buf_putstring(ses.writepayload, "", 0);
136 /* first_kex_packet_follows */
137 buf_putbyte(ses.writepayload, (ses.send_kex_first_guess != NULL));
139 /* reserved unit32 */
140 buf_putint(ses.writepayload, 0);
142 /* set up transmitted kex packet buffer for hashing.
143 * This is freed after the end of the kex */
144 ses.transkexinit = buf_newcopy(ses.writepayload);
146 encrypt_packet();
147 ses.dataallowed = 0; /* don't send other packets during kex */
149 ses.kexstate.sentkexinit = 1;
151 ses.newkeys = (struct key_context*)m_malloc(sizeof(struct key_context));
153 if (ses.send_kex_first_guess) {
154 ses.newkeys->algo_kex = sshkex[0].data;
155 ses.newkeys->algo_hostkey = sshhostkey[0].val;
156 ses.send_kex_first_guess();
159 TRACE(("DATAALLOWED=0"))
160 TRACE(("-> KEXINIT"))
164 static void switch_keys() {
165 TRACE2(("enter switch_keys"))
166 if (!(ses.kexstate.sentkexinit && ses.kexstate.recvkexinit)) {
167 dropbear_exit("Unexpected newkeys message");
170 if (!ses.keys) {
171 ses.keys = m_malloc(sizeof(*ses.newkeys));
173 if (ses.kexstate.recvnewkeys && ses.newkeys->recv.valid) {
174 TRACE(("switch_keys recv"))
175 #ifndef DISABLE_ZLIB
176 gen_new_zstream_recv();
177 #endif
178 ses.keys->recv = ses.newkeys->recv;
179 m_burn(&ses.newkeys->recv, sizeof(ses.newkeys->recv));
180 ses.newkeys->recv.valid = 0;
182 if (ses.kexstate.sentnewkeys && ses.newkeys->trans.valid) {
183 TRACE(("switch_keys trans"))
184 #ifndef DISABLE_ZLIB
185 gen_new_zstream_trans();
186 #endif
187 ses.keys->trans = ses.newkeys->trans;
188 m_burn(&ses.newkeys->trans, sizeof(ses.newkeys->trans));
189 ses.newkeys->trans.valid = 0;
191 if (ses.kexstate.sentnewkeys && ses.kexstate.recvnewkeys)
193 TRACE(("switch_keys done"))
194 ses.keys->algo_kex = ses.newkeys->algo_kex;
195 ses.keys->algo_hostkey = ses.newkeys->algo_hostkey;
196 ses.keys->allow_compress = 0;
197 m_free(ses.newkeys);
198 ses.newkeys = NULL;
199 kexinitialise();
201 TRACE2(("leave switch_keys"))
204 /* Bring new keys into use after a key exchange, and let the client know*/
205 void send_msg_newkeys() {
207 TRACE(("enter send_msg_newkeys"))
209 /* generate the kexinit request */
210 CHECKCLEARTOWRITE();
211 buf_putbyte(ses.writepayload, SSH_MSG_NEWKEYS);
212 encrypt_packet();
215 /* set up our state */
216 ses.kexstate.sentnewkeys = 1;
217 ses.kexstate.donefirstkex = 1;
218 ses.dataallowed = 1; /* we can send other packets again now */
219 gen_new_keys();
220 switch_keys();
222 TRACE(("leave send_msg_newkeys"))
225 /* Bring the new keys into use after a key exchange */
226 void recv_msg_newkeys() {
228 TRACE(("enter recv_msg_newkeys"))
230 ses.kexstate.recvnewkeys = 1;
231 switch_keys();
233 TRACE(("leave recv_msg_newkeys"))
237 /* Set up the kex for the first time */
238 void kexfirstinitialise() {
239 ses.kexstate.donefirstkex = 0;
241 #ifndef DISABLE_ZLIB
242 if (opts.enable_compress) {
243 ses.compress_algos = ssh_compress;
244 } else
245 #endif
247 ses.compress_algos = ssh_nocompress;
249 kexinitialise();
252 /* Reset the kex state, ready for a new negotiation */
253 static void kexinitialise() {
255 TRACE(("kexinitialise()"))
257 /* sent/recv'd MSG_KEXINIT */
258 ses.kexstate.sentkexinit = 0;
259 ses.kexstate.recvkexinit = 0;
261 /* sent/recv'd MSG_NEWKEYS */
262 ses.kexstate.recvnewkeys = 0;
263 ses.kexstate.sentnewkeys = 0;
265 /* first_packet_follows */
266 ses.kexstate.them_firstfollows = 0;
268 ses.kexstate.datatrans = 0;
269 ses.kexstate.datarecv = 0;
271 ses.kexstate.our_first_follows_matches = 0;
273 ses.kexstate.lastkextime = time(NULL);
277 /* Helper function for gen_new_keys, creates a hash. It makes a copy of the
278 * already initialised hash_state hs, which should already have processed
279 * the dh_K and hash, since these are common. X is the letter 'A', 'B' etc.
280 * out must have at least min(SHA1_HASH_SIZE, outlen) bytes allocated.
282 * See Section 7.2 of rfc4253 (ssh transport) for details */
283 static void hashkeys(unsigned char *out, unsigned int outlen,
284 const hash_state * hs, const unsigned char X) {
286 const struct ltc_hash_descriptor *hash_desc = ses.newkeys->algo_kex->hash_desc;
287 hash_state hs2;
288 unsigned int offset;
289 unsigned char tmpout[MAX_HASH_SIZE];
291 memcpy(&hs2, hs, sizeof(hash_state));
292 hash_desc->process(&hs2, &X, 1);
293 hash_desc->process(&hs2, ses.session_id->data, ses.session_id->len);
294 hash_desc->done(&hs2, tmpout);
295 memcpy(out, tmpout, MIN(hash_desc->hashsize, outlen));
296 for (offset = hash_desc->hashsize;
297 offset < outlen;
298 offset += hash_desc->hashsize)
300 /* need to extend */
301 memcpy(&hs2, hs, sizeof(hash_state));
302 hash_desc->process(&hs2, out, offset);
303 hash_desc->done(&hs2, tmpout);
304 memcpy(&out[offset], tmpout, MIN(outlen - offset, hash_desc->hashsize));
309 /* Generate the actual encryption/integrity keys, using the results of the
310 * key exchange, as specified in section 7.2 of the transport rfc 4253.
311 * This occurs after the DH key-exchange.
313 * ses.newkeys is the new set of keys which are generated, these are only
314 * taken into use after both sides have sent a newkeys message */
316 static void gen_new_keys() {
318 unsigned char C2S_IV[MAX_IV_LEN];
319 unsigned char C2S_key[MAX_KEY_LEN];
320 unsigned char S2C_IV[MAX_IV_LEN];
321 unsigned char S2C_key[MAX_KEY_LEN];
322 /* unsigned char key[MAX_KEY_LEN]; */
323 unsigned char *trans_IV, *trans_key, *recv_IV, *recv_key;
325 hash_state hs;
326 const struct ltc_hash_descriptor *hash_desc = ses.newkeys->algo_kex->hash_desc;
327 char mactransletter, macrecvletter; /* Client or server specific */
329 TRACE(("enter gen_new_keys"))
330 /* the dh_K and hash are the start of all hashes, we make use of that */
332 hash_desc->init(&hs);
333 hash_process_mp(hash_desc, &hs, ses.dh_K);
334 mp_clear(ses.dh_K);
335 m_free(ses.dh_K);
336 hash_desc->process(&hs, ses.hash->data, ses.hash->len);
337 buf_burn(ses.hash);
338 buf_free(ses.hash);
339 ses.hash = NULL;
341 if (IS_DROPBEAR_CLIENT) {
342 trans_IV = C2S_IV;
343 recv_IV = S2C_IV;
344 trans_key = C2S_key;
345 recv_key = S2C_key;
346 mactransletter = 'E';
347 macrecvletter = 'F';
348 } else {
349 trans_IV = S2C_IV;
350 recv_IV = C2S_IV;
351 trans_key = S2C_key;
352 recv_key = C2S_key;
353 mactransletter = 'F';
354 macrecvletter = 'E';
357 hashkeys(C2S_IV, sizeof(C2S_IV), &hs, 'A');
358 hashkeys(S2C_IV, sizeof(S2C_IV), &hs, 'B');
359 hashkeys(C2S_key, sizeof(C2S_key), &hs, 'C');
360 hashkeys(S2C_key, sizeof(S2C_key), &hs, 'D');
362 if (ses.newkeys->recv.algo_crypt->cipherdesc != NULL) {
363 int recv_cipher = find_cipher(ses.newkeys->recv.algo_crypt->cipherdesc->name);
364 if (recv_cipher < 0)
365 dropbear_exit("Crypto error");
366 if (ses.newkeys->recv.crypt_mode->start(recv_cipher,
367 recv_IV, recv_key,
368 ses.newkeys->recv.algo_crypt->keysize, 0,
369 &ses.newkeys->recv.cipher_state) != CRYPT_OK) {
370 dropbear_exit("Crypto error");
374 if (ses.newkeys->trans.algo_crypt->cipherdesc != NULL) {
375 int trans_cipher = find_cipher(ses.newkeys->trans.algo_crypt->cipherdesc->name);
376 if (trans_cipher < 0)
377 dropbear_exit("Crypto error");
378 if (ses.newkeys->trans.crypt_mode->start(trans_cipher,
379 trans_IV, trans_key,
380 ses.newkeys->trans.algo_crypt->keysize, 0,
381 &ses.newkeys->trans.cipher_state) != CRYPT_OK) {
382 dropbear_exit("Crypto error");
386 if (ses.newkeys->trans.algo_mac->hash_desc != NULL) {
387 hashkeys(ses.newkeys->trans.mackey,
388 ses.newkeys->trans.algo_mac->keysize, &hs, mactransletter);
389 ses.newkeys->trans.hash_index = find_hash(ses.newkeys->trans.algo_mac->hash_desc->name);
392 if (ses.newkeys->recv.algo_mac->hash_desc != NULL) {
393 hashkeys(ses.newkeys->recv.mackey,
394 ses.newkeys->recv.algo_mac->keysize, &hs, macrecvletter);
395 ses.newkeys->recv.hash_index = find_hash(ses.newkeys->recv.algo_mac->hash_desc->name);
398 /* Ready to switch over */
399 ses.newkeys->trans.valid = 1;
400 ses.newkeys->recv.valid = 1;
402 m_burn(C2S_IV, sizeof(C2S_IV));
403 m_burn(C2S_key, sizeof(C2S_key));
404 m_burn(S2C_IV, sizeof(S2C_IV));
405 m_burn(S2C_key, sizeof(S2C_key));
407 TRACE(("leave gen_new_keys"))
410 #ifndef DISABLE_ZLIB
412 int is_compress_trans() {
413 return ses.keys->trans.algo_comp == DROPBEAR_COMP_ZLIB
414 || (ses.authstate.authdone
415 && ses.keys->trans.algo_comp == DROPBEAR_COMP_ZLIB_DELAY);
418 int is_compress_recv() {
419 return ses.keys->recv.algo_comp == DROPBEAR_COMP_ZLIB
420 || (ses.authstate.authdone
421 && ses.keys->recv.algo_comp == DROPBEAR_COMP_ZLIB_DELAY);
424 /* Set up new zlib compression streams, close the old ones. Only
425 * called from gen_new_keys() */
426 static void gen_new_zstream_recv() {
428 /* create new zstreams */
429 if (ses.newkeys->recv.algo_comp == DROPBEAR_COMP_ZLIB
430 || ses.newkeys->recv.algo_comp == DROPBEAR_COMP_ZLIB_DELAY) {
431 ses.newkeys->recv.zstream = (z_streamp)m_malloc(sizeof(z_stream));
432 ses.newkeys->recv.zstream->zalloc = Z_NULL;
433 ses.newkeys->recv.zstream->zfree = Z_NULL;
435 if (inflateInit(ses.newkeys->recv.zstream) != Z_OK) {
436 dropbear_exit("zlib error");
438 } else {
439 ses.newkeys->recv.zstream = NULL;
441 /* clean up old keys */
442 if (ses.keys->recv.zstream != NULL) {
443 if (inflateEnd(ses.keys->recv.zstream) == Z_STREAM_ERROR) {
444 /* Z_DATA_ERROR is ok, just means that stream isn't ended */
445 dropbear_exit("Crypto error");
447 m_free(ses.keys->recv.zstream);
451 static void gen_new_zstream_trans() {
453 if (ses.newkeys->trans.algo_comp == DROPBEAR_COMP_ZLIB
454 || ses.newkeys->trans.algo_comp == DROPBEAR_COMP_ZLIB_DELAY) {
455 ses.newkeys->trans.zstream = (z_streamp)m_malloc(sizeof(z_stream));
456 ses.newkeys->trans.zstream->zalloc = Z_NULL;
457 ses.newkeys->trans.zstream->zfree = Z_NULL;
459 if (deflateInit2(ses.newkeys->trans.zstream, Z_DEFAULT_COMPRESSION,
460 Z_DEFLATED, DROPBEAR_ZLIB_WINDOW_BITS,
461 DROPBEAR_ZLIB_MEM_LEVEL, Z_DEFAULT_STRATEGY)
462 != Z_OK) {
463 dropbear_exit("zlib error");
465 } else {
466 ses.newkeys->trans.zstream = NULL;
469 if (ses.keys->trans.zstream != NULL) {
470 if (deflateEnd(ses.keys->trans.zstream) == Z_STREAM_ERROR) {
471 /* Z_DATA_ERROR is ok, just means that stream isn't ended */
472 dropbear_exit("Crypto error");
474 m_free(ses.keys->trans.zstream);
477 #endif /* DISABLE_ZLIB */
480 /* Executed upon receiving a kexinit message from the client to initiate
481 * key exchange. If we haven't already done so, we send the list of our
482 * preferred algorithms. The client's requested algorithms are processed,
483 * and we calculate the first portion of the key-exchange-hash for used
484 * later in the key exchange. No response is sent, as the client should
485 * initiate the diffie-hellman key exchange */
487 /* Originally from kex.c, generalized for cli/svr mode --mihnea */
488 /* Belongs in common_kex.c where it should be moved after review */
489 void recv_msg_kexinit() {
491 unsigned int kexhashbuf_len = 0;
492 unsigned int remote_ident_len = 0;
493 unsigned int local_ident_len = 0;
495 TRACE(("<- KEXINIT"))
496 TRACE(("enter recv_msg_kexinit"))
498 if (!ses.kexstate.sentkexinit) {
499 /* we need to send a kex packet */
500 send_msg_kexinit();
501 TRACE(("continue recv_msg_kexinit: sent kexinit"))
504 /* start the kex hash */
505 local_ident_len = strlen(LOCAL_IDENT);
506 remote_ident_len = strlen((char*)ses.remoteident);
508 kexhashbuf_len = local_ident_len + remote_ident_len
509 + ses.transkexinit->len + ses.payload->len
510 + KEXHASHBUF_MAX_INTS;
512 ses.kexhashbuf = buf_new(kexhashbuf_len);
514 if (IS_DROPBEAR_CLIENT) {
516 /* read the peer's choice of algos */
517 read_kex_algos();
519 /* V_C, the client's version string (CR and NL excluded) */
520 buf_putstring(ses.kexhashbuf,
521 (unsigned char*)LOCAL_IDENT, local_ident_len);
522 /* V_S, the server's version string (CR and NL excluded) */
523 buf_putstring(ses.kexhashbuf, ses.remoteident, remote_ident_len);
525 /* I_C, the payload of the client's SSH_MSG_KEXINIT */
526 buf_putstring(ses.kexhashbuf,
527 ses.transkexinit->data, ses.transkexinit->len);
528 /* I_S, the payload of the server's SSH_MSG_KEXINIT */
529 buf_setpos(ses.payload, 0);
530 buf_putstring(ses.kexhashbuf, ses.payload->data, ses.payload->len);
532 } else {
533 /* SERVER */
535 /* read the peer's choice of algos */
536 read_kex_algos();
537 /* V_C, the client's version string (CR and NL excluded) */
538 buf_putstring(ses.kexhashbuf, ses.remoteident, remote_ident_len);
539 /* V_S, the server's version string (CR and NL excluded) */
540 buf_putstring(ses.kexhashbuf,
541 (unsigned char*)LOCAL_IDENT, local_ident_len);
543 /* I_C, the payload of the client's SSH_MSG_KEXINIT */
544 buf_setpos(ses.payload, 0);
545 buf_putstring(ses.kexhashbuf, ses.payload->data, ses.payload->len);
547 /* I_S, the payload of the server's SSH_MSG_KEXINIT */
548 buf_putstring(ses.kexhashbuf,
549 ses.transkexinit->data, ses.transkexinit->len);
551 ses.requirenext[0] = SSH_MSG_KEXDH_INIT;
554 buf_free(ses.transkexinit);
555 ses.transkexinit = NULL;
556 /* the rest of ses.kexhashbuf will be done after DH exchange */
558 ses.kexstate.recvkexinit = 1;
560 TRACE(("leave recv_msg_kexinit"))
563 static void load_dh_p(mp_int * dh_p)
565 bytes_to_mp(dh_p, ses.newkeys->algo_kex->dh_p_bytes,
566 ses.newkeys->algo_kex->dh_p_len);
569 /* Initialises and generate one side of the diffie-hellman key exchange values.
570 * See the transport rfc 4253 section 8 for details */
571 /* dh_pub and dh_priv MUST be already initialised */
572 struct kex_dh_param *gen_kexdh_param() {
573 struct kex_dh_param *param = NULL;
575 DEF_MP_INT(dh_p);
576 DEF_MP_INT(dh_q);
577 DEF_MP_INT(dh_g);
579 TRACE(("enter gen_kexdh_vals"))
581 param = m_malloc(sizeof(*param));
582 m_mp_init_multi(&param->pub, &param->priv, &dh_g, &dh_p, &dh_q, NULL);
584 /* read the prime and generator*/
585 load_dh_p(&dh_p);
587 if (mp_set_int(&dh_g, DH_G_VAL) != MP_OKAY) {
588 dropbear_exit("Diffie-Hellman error");
591 /* calculate q = (p-1)/2 */
592 /* dh_priv is just a temp var here */
593 if (mp_sub_d(&dh_p, 1, &param->priv) != MP_OKAY) {
594 dropbear_exit("Diffie-Hellman error");
596 if (mp_div_2(&param->priv, &dh_q) != MP_OKAY) {
597 dropbear_exit("Diffie-Hellman error");
600 /* Generate a private portion 0 < dh_priv < dh_q */
601 gen_random_mpint(&dh_q, &param->priv);
603 /* f = g^y mod p */
604 if (mp_exptmod(&dh_g, &param->priv, &dh_p, &param->pub) != MP_OKAY) {
605 dropbear_exit("Diffie-Hellman error");
607 mp_clear_multi(&dh_g, &dh_p, &dh_q, NULL);
608 return param;
611 void free_kexdh_param(struct kex_dh_param *param)
613 mp_clear_multi(&param->pub, &param->priv, NULL);
614 m_free(param);
617 /* This function is fairly common between client/server, with some substitution
618 * of dh_e/dh_f etc. Hence these arguments:
619 * dh_pub_us is 'e' for the client, 'f' for the server. dh_pub_them is
620 * vice-versa. dh_priv is the x/y value corresponding to dh_pub_us */
621 void kexdh_comb_key(struct kex_dh_param *param, mp_int *dh_pub_them,
622 sign_key *hostkey) {
624 mp_int dh_p;
625 mp_int *dh_e = NULL, *dh_f = NULL;
627 /* read the prime and generator*/
628 m_mp_init(&dh_p);
629 load_dh_p(&dh_p);
631 /* Check that dh_pub_them (dh_e or dh_f) is in the range [1, p-1] */
632 if (mp_cmp(dh_pub_them, &dh_p) != MP_LT
633 || mp_cmp_d(dh_pub_them, 0) != MP_GT) {
634 dropbear_exit("Diffie-Hellman error");
637 /* K = e^y mod p = f^x mod p */
638 m_mp_alloc_init_multi(&ses.dh_K, NULL);
639 if (mp_exptmod(dh_pub_them, &param->priv, &dh_p, ses.dh_K) != MP_OKAY) {
640 dropbear_exit("Diffie-Hellman error");
643 /* clear no longer needed vars */
644 mp_clear_multi(&dh_p, NULL);
646 /* From here on, the code needs to work with the _same_ vars on each side,
647 * not vice-versaing for client/server */
648 if (IS_DROPBEAR_CLIENT) {
649 dh_e = &param->pub;
650 dh_f = dh_pub_them;
651 } else {
652 dh_e = dh_pub_them;
653 dh_f = &param->pub;
656 /* Create the remainder of the hash buffer, to generate the exchange hash */
657 /* K_S, the host key */
658 buf_put_pub_key(ses.kexhashbuf, hostkey, ses.newkeys->algo_hostkey);
659 /* e, exchange value sent by the client */
660 buf_putmpint(ses.kexhashbuf, dh_e);
661 /* f, exchange value sent by the server */
662 buf_putmpint(ses.kexhashbuf, dh_f);
663 /* K, the shared secret */
664 buf_putmpint(ses.kexhashbuf, ses.dh_K);
666 /* calculate the hash H to sign */
667 finish_kexhashbuf();
670 #ifdef DROPBEAR_ECDH
671 struct kex_ecdh_param *gen_kexecdh_param() {
672 struct kex_ecdh_param *param = m_malloc(sizeof(*param));
673 if (ecc_make_key_ex(NULL, dropbear_ltc_prng,
674 &param->key, ses.newkeys->algo_kex->ecc_curve->dp) != CRYPT_OK) {
675 dropbear_exit("ECC error");
677 return param;
680 void free_kexecdh_param(struct kex_ecdh_param *param) {
681 ecc_free(&param->key);
682 m_free(param);
685 void kexecdh_comb_key(struct kex_ecdh_param *param, buffer *pub_them,
686 sign_key *hostkey) {
687 const struct dropbear_kex *algo_kex = ses.newkeys->algo_kex;
688 /* public keys from client and server */
689 ecc_key *Q_C, *Q_S, *Q_them;
691 Q_them = buf_get_ecc_raw_pubkey(pub_them, algo_kex->ecc_curve);
693 ses.dh_K = dropbear_ecc_shared_secret(Q_them, &param->key);
695 /* Create the remainder of the hash buffer, to generate the exchange hash
696 See RFC5656 section 4 page 7 */
697 if (IS_DROPBEAR_CLIENT) {
698 Q_C = &param->key;
699 Q_S = Q_them;
700 } else {
701 Q_C = Q_them;
702 Q_S = &param->key;
705 /* K_S, the host key */
706 buf_put_pub_key(ses.kexhashbuf, hostkey, ses.newkeys->algo_hostkey);
707 /* Q_C, client's ephemeral public key octet string */
708 buf_put_ecc_raw_pubkey_string(ses.kexhashbuf, Q_C);
709 /* Q_S, server's ephemeral public key octet string */
710 buf_put_ecc_raw_pubkey_string(ses.kexhashbuf, Q_S);
711 /* K, the shared secret */
712 buf_putmpint(ses.kexhashbuf, ses.dh_K);
714 /* calculate the hash H to sign */
715 finish_kexhashbuf();
717 #endif /* DROPBEAR_ECDH */
719 #ifdef DROPBEAR_CURVE25519
720 struct kex_curve25519_param *gen_kexcurve25519_param () {
721 /* Per http://cr.yp.to/ecdh.html */
722 struct kex_curve25519_param *param = m_malloc(sizeof(*param));
723 const unsigned char basepoint[32] = {9};
725 genrandom(param->priv, CURVE25519_LEN);
726 param->priv[0] &= 248;
727 param->priv[31] &= 127;
728 param->priv[31] |= 64;
730 curve25519_donna(param->pub, param->priv, basepoint);
732 return param;
735 void free_kexcurve25519_param(struct kex_curve25519_param *param)
737 m_burn(param->priv, CURVE25519_LEN);
738 m_free(param);
741 void kexcurve25519_comb_key(struct kex_curve25519_param *param, buffer *buf_pub_them,
742 sign_key *hostkey) {
743 unsigned char out[CURVE25519_LEN];
744 const unsigned char* Q_C = NULL;
745 const unsigned char* Q_S = NULL;
747 if (buf_pub_them->len != CURVE25519_LEN)
749 dropbear_exit("Bad curve25519");
752 curve25519_donna(out, param->priv, buf_pub_them->data);
753 m_mp_alloc_init_multi(&ses.dh_K, NULL);
754 bytes_to_mp(ses.dh_K, out, CURVE25519_LEN);
755 m_burn(out, sizeof(out));
757 /* Create the remainder of the hash buffer, to generate the exchange hash.
758 See RFC5656 section 4 page 7 */
759 if (IS_DROPBEAR_CLIENT) {
760 Q_C = param->pub;
761 Q_S = buf_pub_them->data;
762 } else {
763 Q_S = param->pub;
764 Q_C = buf_pub_them->data;
767 /* K_S, the host key */
768 buf_put_pub_key(ses.kexhashbuf, hostkey, ses.newkeys->algo_hostkey);
769 /* Q_C, client's ephemeral public key octet string */
770 buf_putstring(ses.kexhashbuf, Q_C, CURVE25519_LEN);
771 /* Q_S, server's ephemeral public key octet string */
772 buf_putstring(ses.kexhashbuf, Q_S, CURVE25519_LEN);
773 /* K, the shared secret */
774 buf_putmpint(ses.kexhashbuf, ses.dh_K);
776 /* calculate the hash H to sign */
777 finish_kexhashbuf();
779 #endif /* DROPBEAR_CURVE25519 */
783 static void finish_kexhashbuf(void) {
784 hash_state hs;
785 const struct ltc_hash_descriptor *hash_desc = ses.newkeys->algo_kex->hash_desc;
787 hash_desc->init(&hs);
788 buf_setpos(ses.kexhashbuf, 0);
789 hash_desc->process(&hs, buf_getptr(ses.kexhashbuf, ses.kexhashbuf->len),
790 ses.kexhashbuf->len);
791 ses.hash = buf_new(hash_desc->hashsize);
792 hash_desc->done(&hs, buf_getwriteptr(ses.hash, hash_desc->hashsize));
793 buf_setlen(ses.hash, hash_desc->hashsize);
795 buf_burn(ses.kexhashbuf);
796 buf_free(ses.kexhashbuf);
797 ses.kexhashbuf = NULL;
799 /* first time around, we set the session_id to H */
800 if (ses.session_id == NULL) {
801 /* create the session_id, this never needs freeing */
802 ses.session_id = buf_newcopy(ses.hash);
807 /* read the other side's algo list. buf_match_algo is a callback to match
808 * algos for the client or server. */
809 static void read_kex_algos() {
811 /* for asymmetry */
812 algo_type * c2s_hash_algo = NULL;
813 algo_type * s2c_hash_algo = NULL;
814 algo_type * c2s_cipher_algo = NULL;
815 algo_type * s2c_cipher_algo = NULL;
816 algo_type * c2s_comp_algo = NULL;
817 algo_type * s2c_comp_algo = NULL;
818 /* the generic one */
819 algo_type * algo = NULL;
821 /* which algo couldn't match */
822 char * erralgo = NULL;
824 int goodguess = 0;
825 int allgood = 1; /* we AND this with each goodguess and see if its still
826 true after */
828 #ifdef USE_KEXGUESS2
829 enum kexguess2_used kexguess2 = KEXGUESS2_LOOK;
830 #else
831 enum kexguess2_used kexguess2 = KEXGUESS2_NO;
832 #endif
834 buf_incrpos(ses.payload, 16); /* start after the cookie */
836 memset(ses.newkeys, 0x0, sizeof(*ses.newkeys));
838 /* kex_algorithms */
839 algo = buf_match_algo(ses.payload, sshkex, &kexguess2, &goodguess);
840 allgood &= goodguess;
841 if (algo == NULL || algo->val == KEXGUESS2_ALGO_ID) {
842 erralgo = "kex";
843 goto error;
845 TRACE(("kexguess2 %d", kexguess2))
846 TRACE(("kex algo %s", algo->name))
847 ses.newkeys->algo_kex = algo->data;
849 /* server_host_key_algorithms */
850 algo = buf_match_algo(ses.payload, sshhostkey, &kexguess2, &goodguess);
851 allgood &= goodguess;
852 if (algo == NULL) {
853 erralgo = "hostkey";
854 goto error;
856 TRACE(("hostkey algo %s", algo->name))
857 ses.newkeys->algo_hostkey = algo->val;
859 /* encryption_algorithms_client_to_server */
860 c2s_cipher_algo = buf_match_algo(ses.payload, sshciphers, NULL, NULL);
861 if (c2s_cipher_algo == NULL) {
862 erralgo = "enc c->s";
863 goto error;
865 TRACE(("enc c2s is %s", c2s_cipher_algo->name))
867 /* encryption_algorithms_server_to_client */
868 s2c_cipher_algo = buf_match_algo(ses.payload, sshciphers, NULL, NULL);
869 if (s2c_cipher_algo == NULL) {
870 erralgo = "enc s->c";
871 goto error;
873 TRACE(("enc s2c is %s", s2c_cipher_algo->name))
875 /* mac_algorithms_client_to_server */
876 c2s_hash_algo = buf_match_algo(ses.payload, sshhashes, NULL, NULL);
877 if (c2s_hash_algo == NULL) {
878 erralgo = "mac c->s";
879 goto error;
881 TRACE(("hash c2s is %s", c2s_hash_algo->name))
883 /* mac_algorithms_server_to_client */
884 s2c_hash_algo = buf_match_algo(ses.payload, sshhashes, NULL, NULL);
885 if (s2c_hash_algo == NULL) {
886 erralgo = "mac s->c";
887 goto error;
889 TRACE(("hash s2c is %s", s2c_hash_algo->name))
891 /* compression_algorithms_client_to_server */
892 c2s_comp_algo = buf_match_algo(ses.payload, ses.compress_algos, NULL, NULL);
893 if (c2s_comp_algo == NULL) {
894 erralgo = "comp c->s";
895 goto error;
897 TRACE(("hash c2s is %s", c2s_comp_algo->name))
899 /* compression_algorithms_server_to_client */
900 s2c_comp_algo = buf_match_algo(ses.payload, ses.compress_algos, NULL, NULL);
901 if (s2c_comp_algo == NULL) {
902 erralgo = "comp s->c";
903 goto error;
905 TRACE(("hash s2c is %s", s2c_comp_algo->name))
907 /* languages_client_to_server */
908 buf_eatstring(ses.payload);
910 /* languages_server_to_client */
911 buf_eatstring(ses.payload);
913 /* their first_kex_packet_follows */
914 if (buf_getbool(ses.payload)) {
915 TRACE(("them kex firstfollows. allgood %d", allgood))
916 ses.kexstate.them_firstfollows = 1;
917 /* if the guess wasn't good, we ignore the packet sent */
918 if (!allgood) {
919 ses.ignorenext = 1;
923 /* Handle the asymmetry */
924 if (IS_DROPBEAR_CLIENT) {
925 ses.newkeys->recv.algo_crypt =
926 (struct dropbear_cipher*)s2c_cipher_algo->data;
927 ses.newkeys->trans.algo_crypt =
928 (struct dropbear_cipher*)c2s_cipher_algo->data;
929 ses.newkeys->recv.crypt_mode =
930 (struct dropbear_cipher_mode*)s2c_cipher_algo->mode;
931 ses.newkeys->trans.crypt_mode =
932 (struct dropbear_cipher_mode*)c2s_cipher_algo->mode;
933 ses.newkeys->recv.algo_mac =
934 (struct dropbear_hash*)s2c_hash_algo->data;
935 ses.newkeys->trans.algo_mac =
936 (struct dropbear_hash*)c2s_hash_algo->data;
937 ses.newkeys->recv.algo_comp = s2c_comp_algo->val;
938 ses.newkeys->trans.algo_comp = c2s_comp_algo->val;
939 } else {
940 /* SERVER */
941 ses.newkeys->recv.algo_crypt =
942 (struct dropbear_cipher*)c2s_cipher_algo->data;
943 ses.newkeys->trans.algo_crypt =
944 (struct dropbear_cipher*)s2c_cipher_algo->data;
945 ses.newkeys->recv.crypt_mode =
946 (struct dropbear_cipher_mode*)c2s_cipher_algo->mode;
947 ses.newkeys->trans.crypt_mode =
948 (struct dropbear_cipher_mode*)s2c_cipher_algo->mode;
949 ses.newkeys->recv.algo_mac =
950 (struct dropbear_hash*)c2s_hash_algo->data;
951 ses.newkeys->trans.algo_mac =
952 (struct dropbear_hash*)s2c_hash_algo->data;
953 ses.newkeys->recv.algo_comp = c2s_comp_algo->val;
954 ses.newkeys->trans.algo_comp = s2c_comp_algo->val;
957 /* reserved for future extensions */
958 buf_getint(ses.payload);
960 if (ses.send_kex_first_guess && allgood) {
961 TRACE(("our_first_follows_matches 1"))
962 ses.kexstate.our_first_follows_matches = 1;
964 return;
966 error:
967 dropbear_exit("No matching algo %s", erralgo);