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 1.17 2000/08/19 21:34:44 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"
60 extern char *client_version_string;
61 extern char *server_version_string;
62 extern Options options;
68 unsigned char *session_id2 = NULL;
69 int session_id2_len = 0;
72 ssh_kex_dh(Kex *kex, char *host, struct sockaddr *hostaddr,
73 Buffer *client_kexinit, Buffer *server_kexinit)
76 unsigned int klen, kout;
77 char *signature = NULL;
79 char *server_host_key_blob = NULL;
81 unsigned int sbloblen;
83 BIGNUM *dh_server_pub = 0;
84 BIGNUM *shared_secret = 0;
88 debug("Sending SSH2_MSG_KEXDH_INIT.");
89 /* generate and send 'e', client DH public key */
91 packet_start(SSH2_MSG_KEXDH_INIT);
92 packet_put_bignum2(dh->pub_key);
97 fprintf(stderr, "\np= ");
99 fprintf(stderr, "\ng= ");
101 fprintf(stderr, "\npub= ");
102 bignum_print(dh->pub_key);
103 fprintf(stderr, "\n");
104 DHparams_print_fp(stderr, dh);
107 debug("Wait SSH2_MSG_KEXDH_REPLY.");
109 packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY);
111 debug("Got SSH2_MSG_KEXDH_REPLY.");
114 server_host_key_blob = packet_get_string(&sbloblen);
115 server_host_key = dsa_key_from_blob(server_host_key_blob, sbloblen);
116 if (server_host_key == NULL)
117 fatal("cannot decode server_host_key_blob");
119 check_host_key(host, hostaddr, server_host_key,
120 options.user_hostfile2, options.system_hostfile2);
122 /* DH paramter f, server public DH key */
123 dh_server_pub = BN_new();
124 if (dh_server_pub == NULL)
125 fatal("dh_server_pub == NULL");
126 packet_get_bignum2(dh_server_pub, &dlen);
129 fprintf(stderr, "\ndh_server_pub= ");
130 bignum_print(dh_server_pub);
131 fprintf(stderr, "\n");
132 debug("bits %d", BN_num_bits(dh_server_pub));
136 signature = packet_get_string(&slen);
139 if (!dh_pub_is_valid(dh, dh_server_pub))
140 packet_disconnect("bad server public DH value");
143 kbuf = xmalloc(klen);
144 kout = DH_compute_key(kbuf, dh_server_pub, dh);
146 debug("shared secret: len %d/%d", klen, kout);
147 fprintf(stderr, "shared secret == ");
148 for (i = 0; i< kout; i++)
149 fprintf(stderr, "%02x", (kbuf[i])&0xff);
150 fprintf(stderr, "\n");
152 shared_secret = BN_new();
154 BN_bin2bn(kbuf, kout, shared_secret);
155 memset(kbuf, 0, klen);
158 /* calc and verify H */
160 client_version_string,
161 server_version_string,
162 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
163 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
164 server_host_key_blob, sbloblen,
169 xfree(server_host_key_blob);
172 fprintf(stderr, "hash == ");
173 for (i = 0; i< 20; i++)
174 fprintf(stderr, "%02x", (hash[i])&0xff);
175 fprintf(stderr, "\n");
177 if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
178 fatal("dsa_verify failed for server_host_key");
179 key_free(server_host_key);
181 kex_derive_keys(kex, hash, shared_secret);
184 /* save session id */
185 session_id2_len = 20;
186 session_id2 = xmalloc(session_id2_len);
187 memcpy(session_id2, hash, session_id2_len);
191 ssh_kex2(char *host, struct sockaddr *hostaddr)
195 Buffer *client_kexinit, *server_kexinit;
196 char *sprop[PROPOSAL_MAX];
198 if (options.ciphers != NULL) {
199 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
200 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
201 } else if (options.cipher == SSH_CIPHER_3DES) {
202 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
203 myproposal[PROPOSAL_ENC_ALGS_STOC] =
204 (char *) cipher_name(SSH_CIPHER_3DES_CBC);
205 } else if (options.cipher == SSH_CIPHER_BLOWFISH) {
206 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
207 myproposal[PROPOSAL_ENC_ALGS_STOC] =
208 (char *) cipher_name(SSH_CIPHER_BLOWFISH_CBC);
210 if (options.compression) {
211 myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
212 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
214 myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
215 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
218 /* buffers with raw kexinit messages */
219 server_kexinit = xmalloc(sizeof(*server_kexinit));
220 buffer_init(server_kexinit);
221 client_kexinit = kex_init(myproposal);
223 /* algorithm negotiation */
224 kex_exchange_kexinit(client_kexinit, server_kexinit, sprop);
225 kex = kex_choose_conf(myproposal, sprop, 0);
226 for (i = 0; i < PROPOSAL_MAX; i++)
229 /* server authentication and session key agreement */
230 ssh_kex_dh(kex, host, hostaddr, client_kexinit, server_kexinit);
232 buffer_free(client_kexinit);
233 buffer_free(server_kexinit);
234 xfree(client_kexinit);
235 xfree(server_kexinit);
237 debug("Wait SSH2_MSG_NEWKEYS.");
238 packet_read_expect(&plen, SSH2_MSG_NEWKEYS);
240 debug("GOT SSH2_MSG_NEWKEYS.");
242 debug("send SSH2_MSG_NEWKEYS.");
243 packet_start(SSH2_MSG_NEWKEYS);
246 debug("done: send SSH2_MSG_NEWKEYS.");
249 /* send 1st encrypted/maced/compressed message */
250 packet_start(SSH2_MSG_IGNORE);
251 packet_put_cstring("markus");
255 debug("done: KEX2.");
262 ssh2_try_passwd(const char *server_user, const char *host, const char *service)
264 static int attempt = 0;
268 if (attempt++ >= options.number_of_password_prompts)
272 error("Permission denied, please try again.");
274 snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
276 password = read_passphrase(prompt, 0);
277 packet_start(SSH2_MSG_USERAUTH_REQUEST);
278 packet_put_cstring(server_user);
279 packet_put_cstring(service);
280 packet_put_cstring("password");
282 packet_put_cstring(password);
283 memset(password, 0, strlen(password));
292 unsigned char **sigp, int *lenp,
293 unsigned char *data, int datalen);
296 ssh2_sign_and_send_pubkey(Key *k, sign_fn *do_sign,
297 const char *server_user, const char *host, const char *service)
300 unsigned char *blob, *signature;
305 dsa_make_key_blob(k, &blob, &bloblen);
307 /* data to be signed */
309 if (datafellows & SSH_COMPAT_SESSIONID_ENCODING) {
310 buffer_put_string(&b, session_id2, session_id2_len);
311 skip = buffer_len(&b);
313 buffer_append(&b, session_id2, session_id2_len);
314 skip = session_id2_len;
316 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
317 buffer_put_cstring(&b, server_user);
318 buffer_put_cstring(&b,
319 datafellows & SSH_BUG_PUBKEYAUTH ?
322 buffer_put_cstring(&b, "publickey");
323 buffer_put_char(&b, 1);
324 buffer_put_cstring(&b, KEX_DSS);
325 buffer_put_string(&b, blob, bloblen);
327 /* generate signature */
328 ret = do_sign(k, &signature, &slen, buffer_ptr(&b), buffer_len(&b));
337 if (datafellows & SSH_BUG_PUBKEYAUTH) {
339 buffer_append(&b, session_id2, session_id2_len);
340 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
341 buffer_put_cstring(&b, server_user);
342 buffer_put_cstring(&b, service);
343 buffer_put_cstring(&b, "publickey");
344 buffer_put_char(&b, 1);
345 buffer_put_cstring(&b, KEX_DSS);
346 buffer_put_string(&b, blob, bloblen);
349 /* append signature */
350 buffer_put_string(&b, signature, slen);
353 /* skip session id and packet type */
354 if (buffer_len(&b) < skip + 1)
355 fatal("ssh2_try_pubkey: internal error");
356 buffer_consume(&b, skip + 1);
358 /* put remaining data from buffer into packet */
359 packet_start(SSH2_MSG_USERAUTH_REQUEST);
360 packet_put_raw(buffer_ptr(&b), buffer_len(&b));
371 ssh2_try_pubkey(char *filename,
372 const char *server_user, const char *host, const char *service)
378 if (stat(filename, &st) != 0) {
379 debug("key does not exist: %s", filename);
382 debug("try pubkey: %s", filename);
384 k = key_new(KEY_DSA);
385 if (!load_private_key(filename, "", k, NULL)) {
389 snprintf(prompt, sizeof prompt,
390 "Enter passphrase for DSA key '%.100s': ",
392 passphrase = read_passphrase(prompt, 0);
393 success = load_private_key(filename, passphrase, k, NULL);
394 memset(passphrase, 0, strlen(passphrase));
401 ret = ssh2_sign_and_send_pubkey(k, dsa_sign, server_user, host, service);
408 unsigned char **sigp, int *lenp,
409 unsigned char *data, int datalen)
412 AuthenticationConnection *ac = ssh_get_authentication_connection();
414 ret = ssh_agent_sign(ac, key, sigp, lenp, data, datalen);
415 ssh_close_authentication_connection(ac);
421 ssh2_try_agent(AuthenticationConnection *ac,
422 const char *server_user, const char *host, const char *service)
424 static int called = 0;
430 k = ssh_get_first_identity(ac, &comment, 2);
433 k = ssh_get_next_identity(ac, &comment, 2);
437 debug("trying DSA agent key %s", comment);
439 ret = ssh2_sign_and_send_pubkey(k, agent_sign, server_user, host, service);
445 ssh_userauth2(const char *server_user, char *host)
447 AuthenticationConnection *ac = ssh_get_authentication_connection();
455 char *service = "ssh-connection"; /* service name */
457 debug("send SSH2_MSG_SERVICE_REQUEST");
458 packet_start(SSH2_MSG_SERVICE_REQUEST);
459 packet_put_cstring("ssh-userauth");
463 type = packet_read(&plen);
464 if (type != SSH2_MSG_SERVICE_ACCEPT) {
465 fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type);
467 if (packet_remaining() > 0) {
468 char *reply = packet_get_string(&plen);
469 debug("service_accept: %s", reply);
472 /* payload empty for ssh-2.0.13 ?? */
473 debug("buggy server: service_accept w/o service");
476 debug("got SSH2_MSG_SERVICE_ACCEPT");
478 /* INITIAL request for auth */
479 packet_start(SSH2_MSG_USERAUTH_REQUEST);
480 packet_put_cstring(server_user);
481 packet_put_cstring(service);
482 packet_put_cstring("none");
488 type = packet_read(&plen);
489 if (type == SSH2_MSG_USERAUTH_SUCCESS)
491 if (type != SSH2_MSG_USERAUTH_FAILURE)
492 fatal("access denied: %d", type);
493 /* SSH2_MSG_USERAUTH_FAILURE means: try again */
494 auths = packet_get_string(&dlen);
495 debug("authentications that can continue: %s", auths);
496 partial = packet_get_char();
499 debug("partial success");
500 if (options.dsa_authentication &&
501 strstr(auths, "publickey") != NULL) {
503 sent = ssh2_try_agent(ac,
504 server_user, host, service);
506 while (i < options.num_identity_files2) {
507 sent = ssh2_try_pubkey(
508 options.identity_files2[i++],
509 server_user, host, service);
516 if (options.password_authentication &&
517 !options.batch_mode &&
518 strstr(auths, "password") != NULL) {
519 sent = ssh2_try_passwd(server_user, host, service);
523 fatal("Permission denied (%s).", auths);
527 ssh_close_authentication_connection(ac);
529 debug("ssh-userauth2 successfull");