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 1.10 2000/05/08 17:42:25 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;
99 } else if (options.cipher == SSH_CIPHER_3DES) {
100 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
101 myproposal[PROPOSAL_ENC_ALGS_STOC] =
102 cipher_name(SSH_CIPHER_3DES_CBC);
103 } else if (options.cipher == SSH_CIPHER_BLOWFISH) {
104 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
105 myproposal[PROPOSAL_ENC_ALGS_STOC] =
106 cipher_name(SSH_CIPHER_BLOWFISH_CBC);
108 if (options.compression) {
109 myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
110 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
112 myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
113 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
115 for (i = 0; i < PROPOSAL_MAX; i++)
116 cprop[i] = xstrdup(myproposal[i]);
118 client_kexinit = kex_init(cprop);
119 packet_start(SSH2_MSG_KEXINIT);
120 packet_put_raw(buffer_ptr(client_kexinit), buffer_len(client_kexinit));
126 packet_read_expect(&payload_len, SSH2_MSG_KEXINIT);
128 /* save payload for session_id */
129 server_kexinit = xmalloc(sizeof(*server_kexinit));
130 buffer_init(server_kexinit);
131 ptr = packet_get_raw(&payload_len);
132 buffer_append(server_kexinit, ptr, payload_len);
135 for (i = 0; i < 16; i++)
136 (void) packet_get_char();
137 /* kex init proposal strings */
138 for (i = 0; i < PROPOSAL_MAX; i++) {
139 sprop[i] = packet_get_string(NULL);
140 debug("got kexinit string: %s", sprop[i]);
142 i = (int) packet_get_char();
143 debug("first kex follow == %d", i);
144 i = packet_get_int();
145 debug("reserved == %d", i);
148 debug("done read kexinit");
149 kex = kex_choose_conf(cprop, sprop, 0);
153 debug("Sending SSH2_MSG_KEXDH_INIT.");
155 /* generate and send 'e', client DH public key */
156 dh = dh_new_group1();
157 packet_start(SSH2_MSG_KEXDH_INIT);
158 packet_put_bignum2(dh->pub_key);
163 fprintf(stderr, "\np= ");
165 fprintf(stderr, "\ng= ");
167 fprintf(stderr, "\npub= ");
168 bignum_print(dh->pub_key);
169 fprintf(stderr, "\n");
170 DHparams_print_fp(stderr, dh);
173 debug("Wait SSH2_MSG_KEXDH_REPLY.");
175 packet_read_expect(&payload_len, SSH2_MSG_KEXDH_REPLY);
177 debug("Got SSH2_MSG_KEXDH_REPLY.");
180 server_host_key_blob = packet_get_string(&sbloblen);
181 server_host_key = dsa_key_from_blob(server_host_key_blob, sbloblen);
182 if (server_host_key == NULL)
183 fatal("cannot decode server_host_key_blob");
185 check_host_key(host, hostaddr, server_host_key,
186 options.user_hostfile2, options.system_hostfile2);
188 /* DH paramter f, server public DH key */
189 dh_server_pub = BN_new();
190 if (dh_server_pub == NULL)
191 fatal("dh_server_pub == NULL");
192 packet_get_bignum2(dh_server_pub, &dlen);
195 fprintf(stderr, "\ndh_server_pub= ");
196 bignum_print(dh_server_pub);
197 fprintf(stderr, "\n");
198 debug("bits %d", BN_num_bits(dh_server_pub));
202 signature = packet_get_string(&slen);
205 if (!dh_pub_is_valid(dh, dh_server_pub))
206 packet_disconnect("bad server public DH value");
209 kbuf = xmalloc(klen);
210 kout = DH_compute_key(kbuf, dh_server_pub, dh);
212 debug("shared secret: len %d/%d", klen, kout);
213 fprintf(stderr, "shared secret == ");
214 for (i = 0; i< kout; i++)
215 fprintf(stderr, "%02x", (kbuf[i])&0xff);
216 fprintf(stderr, "\n");
218 shared_secret = BN_new();
220 BN_bin2bn(kbuf, kout, shared_secret);
221 memset(kbuf, 0, klen);
224 /* calc and verify H */
226 client_version_string,
227 server_version_string,
228 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
229 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
230 server_host_key_blob, sbloblen,
235 xfree(server_host_key_blob);
236 buffer_free(client_kexinit);
237 buffer_free(server_kexinit);
238 xfree(client_kexinit);
239 xfree(server_kexinit);
241 fprintf(stderr, "hash == ");
242 for (i = 0; i< 20; i++)
243 fprintf(stderr, "%02x", (hash[i])&0xff);
244 fprintf(stderr, "\n");
246 if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
247 fatal("dsa_verify failed for server_host_key");
248 key_free(server_host_key);
250 kex_derive_keys(kex, hash, shared_secret);
253 /* have keys, free DH */
256 /* save session id */
257 session_id2_len = 20;
258 session_id2 = xmalloc(session_id2_len);
259 memcpy(session_id2, hash, session_id2_len);
261 debug("Wait SSH2_MSG_NEWKEYS.");
262 packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
264 debug("GOT SSH2_MSG_NEWKEYS.");
266 debug("send SSH2_MSG_NEWKEYS.");
267 packet_start(SSH2_MSG_NEWKEYS);
270 debug("done: send SSH2_MSG_NEWKEYS.");
273 /* send 1st encrypted/maced/compressed message */
274 packet_start(SSH2_MSG_IGNORE);
275 packet_put_cstring("markus");
279 debug("done: KEX2.");
285 ssh2_try_passwd(const char *server_user, const char *host, const char *service)
287 static int attempt = 0;
291 if (attempt++ > options.number_of_password_prompts)
294 snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
296 password = read_passphrase(prompt, 0);
297 packet_start(SSH2_MSG_USERAUTH_REQUEST);
298 packet_put_cstring(server_user);
299 packet_put_cstring(service);
300 packet_put_cstring("password");
302 packet_put_cstring(password);
303 memset(password, 0, strlen(password));
311 ssh2_try_pubkey(char *filename,
312 const char *server_user, const char *host, const char *service)
316 unsigned char *blob, *signature;
320 if (stat(filename, &st) != 0) {
321 debug("key does not exist: %s", filename);
324 debug("try pubkey: %s", filename);
326 k = key_new(KEY_DSA);
327 if (!load_private_key(filename, "", k, NULL)) {
331 snprintf(prompt, sizeof prompt,
332 "Enter passphrase for DSA key '%.100s': ",
334 passphrase = read_passphrase(prompt, 0);
335 success = load_private_key(filename, passphrase, k, NULL);
336 memset(passphrase, 0, strlen(passphrase));
341 dsa_make_key_blob(k, &blob, &bloblen);
343 /* data to be signed */
345 buffer_append(&b, session_id2, session_id2_len);
346 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
347 buffer_put_cstring(&b, server_user);
348 buffer_put_cstring(&b,
349 datafellows & SSH_BUG_PUBKEYAUTH ?
352 buffer_put_cstring(&b, "publickey");
353 buffer_put_char(&b, 1);
354 buffer_put_cstring(&b, KEX_DSS);
355 buffer_put_string(&b, blob, bloblen);
357 /* generate signature */
358 dsa_sign(k, &signature, &slen, buffer_ptr(&b), buffer_len(&b));
363 if (datafellows & SSH_BUG_PUBKEYAUTH) {
364 /* e.g. ssh-2.0.13: data-to-be-signed != data-on-the-wire */
366 buffer_append(&b, session_id2, session_id2_len);
367 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
368 buffer_put_cstring(&b, server_user);
369 buffer_put_cstring(&b, service);
370 buffer_put_cstring(&b, "publickey");
371 buffer_put_char(&b, 1);
372 buffer_put_cstring(&b, KEX_DSS);
373 buffer_put_string(&b, blob, bloblen);
376 /* append signature */
377 buffer_put_string(&b, signature, slen);
380 /* skip session id and packet type */
381 if (buffer_len(&b) < session_id2_len + 1)
382 fatal("ssh2_try_pubkey: internal error");
383 buffer_consume(&b, session_id2_len + 1);
385 /* put remaining data from buffer into packet */
386 packet_start(SSH2_MSG_USERAUTH_REQUEST);
387 packet_put_raw(buffer_ptr(&b), buffer_len(&b));
397 ssh_userauth2(const char *server_user, char *host)
406 char *service = "ssh-connection"; /* service name */
408 debug("send SSH2_MSG_SERVICE_REQUEST");
409 packet_start(SSH2_MSG_SERVICE_REQUEST);
410 packet_put_cstring("ssh-userauth");
414 type = packet_read(&plen);
415 if (type != SSH2_MSG_SERVICE_ACCEPT) {
416 fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
418 if (packet_remaining() > 0) {
419 char *reply = packet_get_string(&plen);
420 debug("service_accept: %s", reply);
423 /* payload empty for ssh-2.0.13 ?? */
424 debug("buggy server: service_accept w/o service");
427 debug("got SSH2_MSG_SERVICE_ACCEPT");
429 /* INITIAL request for auth */
430 packet_start(SSH2_MSG_USERAUTH_REQUEST);
431 packet_put_cstring(server_user);
432 packet_put_cstring(service);
433 packet_put_cstring("none");
439 type = packet_read(&plen);
440 if (type == SSH2_MSG_USERAUTH_SUCCESS)
442 if (type != SSH2_MSG_USERAUTH_FAILURE)
443 fatal("access denied: %d", type);
444 /* SSH2_MSG_USERAUTH_FAILURE means: try again */
445 auths = packet_get_string(&dlen);
446 debug("authentications that can continue: %s", auths);
447 partial = packet_get_char();
450 debug("partial success");
451 if (options.dsa_authentication &&
452 strstr(auths, "publickey") != NULL) {
453 while (i < options.num_identity_files2) {
454 sent = ssh2_try_pubkey(
455 options.identity_files2[i++],
456 server_user, host, service);
462 if (options.password_authentication &&
463 !options.batch_mode &&
464 strstr(auths, "password") != NULL) {
465 sent = ssh2_try_passwd(server_user, host, service);
469 fatal("Permission denied (%s).", auths);
473 debug("ssh-userauth2 successfull");