2 * Copyright (c) 2000 Markus Friedl. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
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.
12 * 3. All advertising materials mentioning features or use of this software
13 * must display the following acknowledgement:
14 * This product includes software developed by Markus Friedl.
15 * 4. The name of the author may not be used to endorse or promote products
16 * derived from this software without specific prior written permission.
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 RCSID("$OpenBSD: sshconnect2.c,v 1.4 2000/04/27 17:54:01 markus Exp $");
33 #include <openssl/bn.h>
34 #include <openssl/rsa.h>
35 #include <openssl/dsa.h>
36 #include <openssl/md5.h>
37 #include <openssl/dh.h>
38 #include <openssl/hmac.h>
52 #include "myproposal.h"
55 #include "sshconnect.h"
59 extern char *client_version_string;
60 extern char *server_version_string;
61 extern Options options;
67 unsigned char *session_id2 = NULL;
68 int session_id2_len = 0;
71 ssh_kex2(char *host, struct sockaddr *hostaddr)
74 char *cprop[PROPOSAL_MAX];
75 char *sprop[PROPOSAL_MAX];
76 Buffer *client_kexinit;
77 Buffer *server_kexinit;
78 int payload_len, dlen;
79 unsigned int klen, kout;
81 char *signature = NULL;
83 char *server_host_key_blob = NULL;
85 unsigned int sbloblen;
87 BIGNUM *dh_server_pub = 0;
88 BIGNUM *shared_secret = 0;
95 debug("Sending KEX init.");
96 if (options.ciphers != NULL) {
97 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
98 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
100 options.cipher == SSH_CIPHER_ARCFOUR ||
101 options.cipher == SSH_CIPHER_3DES_CBC ||
102 options.cipher == SSH_CIPHER_CAST128_CBC ||
103 options.cipher == SSH_CIPHER_BLOWFISH_CBC) {
104 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
105 myproposal[PROPOSAL_ENC_ALGS_STOC] = cipher_name(options.cipher);
107 if (options.compression) {
108 myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
109 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
111 myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
112 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
114 for (i = 0; i < PROPOSAL_MAX; i++)
115 cprop[i] = xstrdup(myproposal[i]);
117 client_kexinit = kex_init(cprop);
118 packet_start(SSH2_MSG_KEXINIT);
119 packet_put_raw(buffer_ptr(client_kexinit), buffer_len(client_kexinit));
125 packet_read_expect(&payload_len, SSH2_MSG_KEXINIT);
127 /* save payload for session_id */
128 server_kexinit = xmalloc(sizeof(*server_kexinit));
129 buffer_init(server_kexinit);
130 ptr = packet_get_raw(&payload_len);
131 buffer_append(server_kexinit, ptr, payload_len);
134 for (i = 0; i < 16; i++)
135 (void) packet_get_char();
136 /* kex init proposal strings */
137 for (i = 0; i < PROPOSAL_MAX; i++) {
138 sprop[i] = packet_get_string(NULL);
139 debug("got kexinit string: %s", sprop[i]);
141 i = (int) packet_get_char();
142 debug("first kex follow == %d", i);
143 i = packet_get_int();
144 debug("reserved == %d", i);
147 debug("done read kexinit");
148 kex = kex_choose_conf(cprop, sprop, 0);
152 debug("Sending SSH2_MSG_KEXDH_INIT.");
154 /* generate and send 'e', client DH public key */
155 dh = dh_new_group1();
156 packet_start(SSH2_MSG_KEXDH_INIT);
157 packet_put_bignum2(dh->pub_key);
162 fprintf(stderr, "\np= ");
164 fprintf(stderr, "\ng= ");
166 fprintf(stderr, "\npub= ");
167 bignum_print(dh->pub_key);
168 fprintf(stderr, "\n");
169 DHparams_print_fp(stderr, dh);
172 debug("Wait SSH2_MSG_KEXDH_REPLY.");
174 packet_read_expect(&payload_len, SSH2_MSG_KEXDH_REPLY);
176 debug("Got SSH2_MSG_KEXDH_REPLY.");
179 server_host_key_blob = packet_get_string(&sbloblen);
180 server_host_key = dsa_key_from_blob(server_host_key_blob, sbloblen);
181 if (server_host_key == NULL)
182 fatal("cannot decode server_host_key_blob");
184 check_host_key(host, hostaddr, server_host_key,
185 options.user_hostfile2, options.system_hostfile2);
187 /* DH paramter f, server public DH key */
188 dh_server_pub = BN_new();
189 if (dh_server_pub == NULL)
190 fatal("dh_server_pub == NULL");
191 packet_get_bignum2(dh_server_pub, &dlen);
194 fprintf(stderr, "\ndh_server_pub= ");
195 bignum_print(dh_server_pub);
196 fprintf(stderr, "\n");
197 debug("bits %d", BN_num_bits(dh_server_pub));
201 signature = packet_get_string(&slen);
204 if (!dh_pub_is_valid(dh, dh_server_pub))
205 packet_disconnect("bad server public DH value");
208 kbuf = xmalloc(klen);
209 kout = DH_compute_key(kbuf, dh_server_pub, dh);
211 debug("shared secret: len %d/%d", klen, kout);
212 fprintf(stderr, "shared secret == ");
213 for (i = 0; i< kout; i++)
214 fprintf(stderr, "%02x", (kbuf[i])&0xff);
215 fprintf(stderr, "\n");
217 shared_secret = BN_new();
219 BN_bin2bn(kbuf, kout, shared_secret);
220 memset(kbuf, 0, klen);
223 /* calc and verify H */
225 client_version_string,
226 server_version_string,
227 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
228 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
229 server_host_key_blob, sbloblen,
234 xfree(server_host_key_blob);
235 buffer_free(client_kexinit);
236 buffer_free(server_kexinit);
237 xfree(client_kexinit);
238 xfree(server_kexinit);
240 fprintf(stderr, "hash == ");
241 for (i = 0; i< 20; i++)
242 fprintf(stderr, "%02x", (hash[i])&0xff);
243 fprintf(stderr, "\n");
245 if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
246 fatal("dsa_verify failed for server_host_key");
247 key_free(server_host_key);
249 kex_derive_keys(kex, hash, shared_secret);
252 /* have keys, free DH */
255 /* save session id */
256 session_id2_len = 20;
257 session_id2 = xmalloc(session_id2_len);
258 memcpy(session_id2, hash, session_id2_len);
260 debug("Wait SSH2_MSG_NEWKEYS.");
261 packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
263 debug("GOT SSH2_MSG_NEWKEYS.");
265 debug("send SSH2_MSG_NEWKEYS.");
266 packet_start(SSH2_MSG_NEWKEYS);
269 debug("done: send SSH2_MSG_NEWKEYS.");
272 /* send 1st encrypted/maced/compressed message */
273 packet_start(SSH2_MSG_IGNORE);
274 packet_put_cstring("markus");
278 debug("done: KEX2.");
284 ssh2_try_passwd(const char *server_user, const char *host, const char *service)
289 snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
291 password = read_passphrase(prompt, 0);
292 packet_start(SSH2_MSG_USERAUTH_REQUEST);
293 packet_put_cstring(server_user);
294 packet_put_cstring(service);
295 packet_put_cstring("password");
297 packet_put_cstring(password);
298 memset(password, 0, strlen(password));
306 ssh2_try_pubkey(char *filename,
307 const char *server_user, const char *host, const char *service)
311 unsigned char *blob, *signature;
314 debug("try pubkey: %s", filename);
316 k = key_new(KEY_DSA);
317 if (!load_private_key(filename, "", k, NULL)) {
321 snprintf(prompt, sizeof prompt,
322 "Enter passphrase for DSA key '%.100s': ",
324 passphrase = read_passphrase(prompt, 0);
325 success = load_private_key(filename, passphrase, k, NULL);
326 memset(passphrase, 0, strlen(passphrase));
331 dsa_make_key_blob(k, &blob, &bloblen);
333 /* data to be signed */
335 buffer_append(&b, session_id2, session_id2_len);
336 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
337 buffer_put_cstring(&b, server_user);
338 buffer_put_cstring(&b, service);
339 buffer_put_cstring(&b, "publickey");
340 buffer_put_char(&b, 1);
341 buffer_put_cstring(&b, KEX_DSS);
342 buffer_put_string(&b, blob, bloblen);
345 /* generate signature */
346 dsa_sign(k, &signature, &slen, buffer_ptr(&b), buffer_len(&b));
351 /* append signature */
352 buffer_put_string(&b, signature, slen);
355 /* skip session id and packet type */
356 if (buffer_len(&b) < session_id2_len + 1)
357 fatal("ssh2_try_pubkey: internal error");
358 buffer_consume(&b, session_id2_len + 1);
360 /* put remaining data from buffer into packet */
361 packet_start(SSH2_MSG_USERAUTH_REQUEST);
362 packet_put_raw(buffer_ptr(&b), buffer_len(&b));
372 ssh_userauth2(const char *server_user, char *host)
381 char *service = "ssh-connection"; /* service name */
383 debug("send SSH2_MSG_SERVICE_REQUEST");
384 packet_start(SSH2_MSG_SERVICE_REQUEST);
385 packet_put_cstring("ssh-userauth");
389 type = packet_read(&plen);
390 if (type != SSH2_MSG_SERVICE_ACCEPT) {
391 fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
393 if (packet_remaining() > 0) {
394 char *reply = packet_get_string(&plen);
395 debug("service_accept: %s", reply);
398 /* payload empty for ssh-2.0.13 ?? */
399 log("buggy server: service_accept w/o service");
402 debug("got SSH2_MSG_SERVICE_ACCEPT");
404 /* INITIAL request for auth */
405 packet_start(SSH2_MSG_USERAUTH_REQUEST);
406 packet_put_cstring(server_user);
407 packet_put_cstring(service);
408 packet_put_cstring("none");
414 type = packet_read(&plen);
415 if (type == SSH2_MSG_USERAUTH_SUCCESS)
417 if (type != SSH2_MSG_USERAUTH_FAILURE)
418 fatal("access denied: %d", type);
419 /* SSH2_MSG_USERAUTH_FAILURE means: try again */
420 auths = packet_get_string(&dlen);
421 debug("authentications that can continue: %s", auths);
422 partial = packet_get_char();
425 debug("partial success");
426 if (options.rsa_authentication &&
427 strstr(auths, "publickey") != NULL) {
428 while (i < options.num_identity_files2) {
429 sent = ssh2_try_pubkey(
430 options.identity_files2[i++],
431 server_user, host, service);
437 if (options.password_authentication &&
438 !options.batch_mode &&
439 strstr(auths, "password") != NULL) {
440 sent = ssh2_try_passwd(server_user, host, service);
444 fatal("Permission denied (%s).", auths);
448 debug("ssh-userauth2 successfull");