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 1.16 2000/07/16 08:27:22 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_kex_dh(Kex *kex, char *host, struct sockaddr *hostaddr,
72 Buffer *client_kexinit, Buffer *server_kexinit)
75 unsigned int klen, kout;
76 char *signature = NULL;
78 char *server_host_key_blob = NULL;
80 unsigned int sbloblen;
82 BIGNUM *dh_server_pub = 0;
83 BIGNUM *shared_secret = 0;
87 debug("Sending SSH2_MSG_KEXDH_INIT.");
88 /* generate and send 'e', client DH public key */
90 packet_start(SSH2_MSG_KEXDH_INIT);
91 packet_put_bignum2(dh->pub_key);
96 fprintf(stderr, "\np= ");
98 fprintf(stderr, "\ng= ");
100 fprintf(stderr, "\npub= ");
101 bignum_print(dh->pub_key);
102 fprintf(stderr, "\n");
103 DHparams_print_fp(stderr, dh);
106 debug("Wait SSH2_MSG_KEXDH_REPLY.");
108 packet_read_expect(&plen, SSH2_MSG_KEXDH_REPLY);
110 debug("Got SSH2_MSG_KEXDH_REPLY.");
113 server_host_key_blob = packet_get_string(&sbloblen);
114 server_host_key = dsa_key_from_blob(server_host_key_blob, sbloblen);
115 if (server_host_key == NULL)
116 fatal("cannot decode server_host_key_blob");
118 check_host_key(host, hostaddr, server_host_key,
119 options.user_hostfile2, options.system_hostfile2);
121 /* DH paramter f, server public DH key */
122 dh_server_pub = BN_new();
123 if (dh_server_pub == NULL)
124 fatal("dh_server_pub == NULL");
125 packet_get_bignum2(dh_server_pub, &dlen);
128 fprintf(stderr, "\ndh_server_pub= ");
129 bignum_print(dh_server_pub);
130 fprintf(stderr, "\n");
131 debug("bits %d", BN_num_bits(dh_server_pub));
135 signature = packet_get_string(&slen);
138 if (!dh_pub_is_valid(dh, dh_server_pub))
139 packet_disconnect("bad server public DH value");
142 kbuf = xmalloc(klen);
143 kout = DH_compute_key(kbuf, dh_server_pub, dh);
145 debug("shared secret: len %d/%d", klen, kout);
146 fprintf(stderr, "shared secret == ");
147 for (i = 0; i< kout; i++)
148 fprintf(stderr, "%02x", (kbuf[i])&0xff);
149 fprintf(stderr, "\n");
151 shared_secret = BN_new();
153 BN_bin2bn(kbuf, kout, shared_secret);
154 memset(kbuf, 0, klen);
157 /* calc and verify H */
159 client_version_string,
160 server_version_string,
161 buffer_ptr(client_kexinit), buffer_len(client_kexinit),
162 buffer_ptr(server_kexinit), buffer_len(server_kexinit),
163 server_host_key_blob, sbloblen,
168 xfree(server_host_key_blob);
171 fprintf(stderr, "hash == ");
172 for (i = 0; i< 20; i++)
173 fprintf(stderr, "%02x", (hash[i])&0xff);
174 fprintf(stderr, "\n");
176 if (dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20) != 1)
177 fatal("dsa_verify failed for server_host_key");
178 key_free(server_host_key);
180 kex_derive_keys(kex, hash, shared_secret);
183 /* save session id */
184 session_id2_len = 20;
185 session_id2 = xmalloc(session_id2_len);
186 memcpy(session_id2, hash, session_id2_len);
190 ssh_kex2(char *host, struct sockaddr *hostaddr)
194 Buffer *client_kexinit, *server_kexinit;
195 char *sprop[PROPOSAL_MAX];
197 if (options.ciphers != NULL) {
198 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
199 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
200 } else if (options.cipher == SSH_CIPHER_3DES) {
201 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
202 myproposal[PROPOSAL_ENC_ALGS_STOC] =
203 (char *) cipher_name(SSH_CIPHER_3DES_CBC);
204 } else if (options.cipher == SSH_CIPHER_BLOWFISH) {
205 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
206 myproposal[PROPOSAL_ENC_ALGS_STOC] =
207 (char *) cipher_name(SSH_CIPHER_BLOWFISH_CBC);
209 if (options.compression) {
210 myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib";
211 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib";
213 myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none";
214 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
217 /* buffers with raw kexinit messages */
218 server_kexinit = xmalloc(sizeof(*server_kexinit));
219 buffer_init(server_kexinit);
220 client_kexinit = kex_init(myproposal);
222 /* algorithm negotiation */
223 kex_exchange_kexinit(client_kexinit, server_kexinit, sprop);
224 kex = kex_choose_conf(myproposal, sprop, 0);
225 for (i = 0; i < PROPOSAL_MAX; i++)
228 /* server authentication and session key agreement */
229 ssh_kex_dh(kex, host, hostaddr, client_kexinit, server_kexinit);
231 buffer_free(client_kexinit);
232 buffer_free(server_kexinit);
233 xfree(client_kexinit);
234 xfree(server_kexinit);
236 debug("Wait SSH2_MSG_NEWKEYS.");
237 packet_read_expect(&plen, SSH2_MSG_NEWKEYS);
239 debug("GOT SSH2_MSG_NEWKEYS.");
241 debug("send SSH2_MSG_NEWKEYS.");
242 packet_start(SSH2_MSG_NEWKEYS);
245 debug("done: send SSH2_MSG_NEWKEYS.");
248 /* send 1st encrypted/maced/compressed message */
249 packet_start(SSH2_MSG_IGNORE);
250 packet_put_cstring("markus");
254 debug("done: KEX2.");
261 ssh2_try_passwd(const char *server_user, const char *host, const char *service)
263 static int attempt = 0;
267 if (attempt++ >= options.number_of_password_prompts)
271 error("Permission denied, please try again.");
273 snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ",
275 password = read_passphrase(prompt, 0);
276 packet_start(SSH2_MSG_USERAUTH_REQUEST);
277 packet_put_cstring(server_user);
278 packet_put_cstring(service);
279 packet_put_cstring("password");
281 packet_put_cstring(password);
282 memset(password, 0, strlen(password));
291 unsigned char **sigp, int *lenp,
292 unsigned char *data, int datalen);
295 ssh2_sign_and_send_pubkey(Key *k, sign_fn *do_sign,
296 const char *server_user, const char *host, const char *service)
299 unsigned char *blob, *signature;
303 dsa_make_key_blob(k, &blob, &bloblen);
305 /* data to be signed */
307 if (datafellows & SSH_COMPAT_SESSIONID_ENCODING) {
308 buffer_put_string(&b, session_id2, session_id2_len);
309 skip = buffer_len(&b);
311 buffer_append(&b, session_id2, session_id2_len);
312 skip = session_id2_len;
314 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
315 buffer_put_cstring(&b, server_user);
316 buffer_put_cstring(&b,
317 datafellows & SSH_BUG_PUBKEYAUTH ?
320 buffer_put_cstring(&b, "publickey");
321 buffer_put_char(&b, 1);
322 buffer_put_cstring(&b, KEX_DSS);
323 buffer_put_string(&b, blob, bloblen);
325 /* generate signature */
326 do_sign(k, &signature, &slen, buffer_ptr(&b), buffer_len(&b));
327 key_free(k); /* XXX */
331 if (datafellows & SSH_BUG_PUBKEYAUTH) {
333 buffer_append(&b, session_id2, session_id2_len);
334 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
335 buffer_put_cstring(&b, server_user);
336 buffer_put_cstring(&b, service);
337 buffer_put_cstring(&b, "publickey");
338 buffer_put_char(&b, 1);
339 buffer_put_cstring(&b, KEX_DSS);
340 buffer_put_string(&b, blob, bloblen);
343 /* append signature */
344 buffer_put_string(&b, signature, slen);
347 /* skip session id and packet type */
348 if (buffer_len(&b) < skip + 1)
349 fatal("ssh2_try_pubkey: internal error");
350 buffer_consume(&b, skip + 1);
352 /* put remaining data from buffer into packet */
353 packet_start(SSH2_MSG_USERAUTH_REQUEST);
354 packet_put_raw(buffer_ptr(&b), buffer_len(&b));
363 ssh2_try_pubkey(char *filename,
364 const char *server_user, const char *host, const char *service)
369 if (stat(filename, &st) != 0) {
370 debug("key does not exist: %s", filename);
373 debug("try pubkey: %s", filename);
375 k = key_new(KEY_DSA);
376 if (!load_private_key(filename, "", k, NULL)) {
380 snprintf(prompt, sizeof prompt,
381 "Enter passphrase for DSA key '%.100s': ",
383 passphrase = read_passphrase(prompt, 0);
384 success = load_private_key(filename, passphrase, k, NULL);
385 memset(passphrase, 0, strlen(passphrase));
392 ssh2_sign_and_send_pubkey(k, dsa_sign, server_user, host, service);
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");