1 /* $OpenBSD: sshconnect1.c,v 1.74 2014/02/02 03:44:32 djm Exp $ */
2 /*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
6 * Code to connect to a remote host, and to perform the client side of the
7 * login (authentication) dialog.
8 *
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
14 */
15
16 #include "includes.h"
17
18 #include <sys/types.h>
19 #include <sys/socket.h>
20
21 #include <openssl/bn.h>
22
23 #include <stdarg.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <signal.h>
28 #include <pwd.h>
29
30 #include "xmalloc.h"
31 #include "ssh.h"
32 #include "ssh1.h"
33 #include "rsa.h"
34 #include "buffer.h"
35 #include "packet.h"
36 #include "key.h"
37 #include "cipher.h"
38 #include "kex.h"
39 #include "uidswap.h"
40 #include "log.h"
41 #include "readconf.h"
42 #include "authfd.h"
43 #include "sshconnect.h"
44 #include "authfile.h"
45 #include "misc.h"
46 #include "canohost.h"
47 #include "hostfile.h"
48 #include "auth.h"
49 #include "digest.h"
50
51 /* Session id for the current session. */
52 u_char session_id[16];
53 u_int supported_authentications = 0;
54
55 extern Options options;
56 extern char *__progname;
57
58 /*
59 * Checks if the user has an authentication agent, and if so, tries to
60 * authenticate using the agent.
61 */
62 static int
try_agent_authentication(void)63 try_agent_authentication(void)
64 {
65 int type;
66 char *comment;
67 AuthenticationConnection *auth;
68 u_char response[16];
69 u_int i;
70 Key *key;
71 BIGNUM *challenge;
72
73 /* Get connection to the agent. */
74 auth = ssh_get_authentication_connection();
75 if (!auth)
76 return 0;
77
78 if ((challenge = BN_new()) == NULL)
79 fatal("try_agent_authentication: BN_new failed");
80 /* Loop through identities served by the agent. */
81 for (key = ssh_get_first_identity(auth, &comment, 1);
82 key != NULL;
83 key = ssh_get_next_identity(auth, &comment, 1)) {
84
85 /* Try this identity. */
86 debug("Trying RSA authentication via agent with '%.100s'", comment);
87 free(comment);
88
89 /* Tell the server that we are willing to authenticate using this key. */
90 packet_start(SSH_CMSG_AUTH_RSA);
91 packet_put_bignum(key->rsa->n);
92 packet_send();
93 packet_write_wait();
94
95 /* Wait for server's response. */
96 type = packet_read();
97
98 /* The server sends failure if it doesn't like our key or
99 does not support RSA authentication. */
100 if (type == SSH_SMSG_FAILURE) {
101 debug("Server refused our key.");
102 key_free(key);
103 continue;
104 }
105 /* Otherwise it should have sent a challenge. */
106 if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
107 packet_disconnect("Protocol error during RSA authentication: %d",
108 type);
109
110 packet_get_bignum(challenge);
111 packet_check_eom();
112
113 debug("Received RSA challenge from server.");
114
115 /* Ask the agent to decrypt the challenge. */
116 if (!ssh_decrypt_challenge(auth, key, challenge, session_id, 1, response)) {
117 /*
118 * The agent failed to authenticate this identifier
119 * although it advertised it supports this. Just
120 * return a wrong value.
121 */
122 logit("Authentication agent failed to decrypt challenge.");
123 explicit_bzero(response, sizeof(response));
124 }
125 key_free(key);
126 debug("Sending response to RSA challenge.");
127
128 /* Send the decrypted challenge back to the server. */
129 packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
130 for (i = 0; i < 16; i++)
131 packet_put_char(response[i]);
132 packet_send();
133 packet_write_wait();
134
135 /* Wait for response from the server. */
136 type = packet_read();
137
138 /* The server returns success if it accepted the authentication. */
139 if (type == SSH_SMSG_SUCCESS) {
140 ssh_close_authentication_connection(auth);
141 BN_clear_free(challenge);
142 debug("RSA authentication accepted by server.");
143 return 1;
144 }
145 /* Otherwise it should return failure. */
146 if (type != SSH_SMSG_FAILURE)
147 packet_disconnect("Protocol error waiting RSA auth response: %d",
148 type);
149 }
150 ssh_close_authentication_connection(auth);
151 BN_clear_free(challenge);
152 debug("RSA authentication using agent refused.");
153 return 0;
154 }
155
156 /*
157 * Computes the proper response to a RSA challenge, and sends the response to
158 * the server.
159 */
160 static void
respond_to_rsa_challenge(BIGNUM * challenge,RSA * prv)161 respond_to_rsa_challenge(BIGNUM * challenge, RSA * prv)
162 {
163 u_char buf[32], response[16];
164 struct ssh_digest_ctx *md;
165 int i, len;
166
167 /* Decrypt the challenge using the private key. */
168 /* XXX think about Bleichenbacher, too */
169 if (rsa_private_decrypt(challenge, challenge, prv) <= 0)
170 packet_disconnect(
171 "respond_to_rsa_challenge: rsa_private_decrypt failed");
172
173 /* Compute the response. */
174 /* The response is MD5 of decrypted challenge plus session id. */
175 len = BN_num_bytes(challenge);
176 if (len <= 0 || (u_int)len > sizeof(buf))
177 packet_disconnect(
178 "respond_to_rsa_challenge: bad challenge length %d", len);
179
180 memset(buf, 0, sizeof(buf));
181 BN_bn2bin(challenge, buf + sizeof(buf) - len);
182 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
183 ssh_digest_update(md, buf, 32) < 0 ||
184 ssh_digest_update(md, session_id, 16) < 0 ||
185 ssh_digest_final(md, response, sizeof(response)) < 0)
186 fatal("%s: md5 failed", __func__);
187 ssh_digest_free(md);
188
189 debug("Sending response to host key RSA challenge.");
190
191 /* Send the response back to the server. */
192 packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
193 for (i = 0; i < 16; i++)
194 packet_put_char(response[i]);
195 packet_send();
196 packet_write_wait();
197
198 explicit_bzero(buf, sizeof(buf));
199 explicit_bzero(response, sizeof(response));
200 explicit_bzero(&md, sizeof(md));
201 }
202
203 /*
204 * Checks if the user has authentication file, and if so, tries to authenticate
205 * the user using it.
206 */
207 static int
try_rsa_authentication(int idx)208 try_rsa_authentication(int idx)
209 {
210 BIGNUM *challenge;
211 Key *public, *private;
212 char buf[300], *passphrase, *comment, *authfile;
213 int i, perm_ok = 1, type, quit;
214
215 public = options.identity_keys[idx];
216 authfile = options.identity_files[idx];
217 comment = xstrdup(authfile);
218
219 debug("Trying RSA authentication with key '%.100s'", comment);
220
221 /* Tell the server that we are willing to authenticate using this key. */
222 packet_start(SSH_CMSG_AUTH_RSA);
223 packet_put_bignum(public->rsa->n);
224 packet_send();
225 packet_write_wait();
226
227 /* Wait for server's response. */
228 type = packet_read();
229
230 /*
231 * The server responds with failure if it doesn't like our key or
232 * doesn't support RSA authentication.
233 */
234 if (type == SSH_SMSG_FAILURE) {
235 debug("Server refused our key.");
236 free(comment);
237 return 0;
238 }
239 /* Otherwise, the server should respond with a challenge. */
240 if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
241 packet_disconnect("Protocol error during RSA authentication: %d", type);
242
243 /* Get the challenge from the packet. */
244 if ((challenge = BN_new()) == NULL)
245 fatal("try_rsa_authentication: BN_new failed");
246 packet_get_bignum(challenge);
247 packet_check_eom();
248
249 debug("Received RSA challenge from server.");
250
251 /*
252 * If the key is not stored in external hardware, we have to
253 * load the private key. Try first with empty passphrase; if it
254 * fails, ask for a passphrase.
255 */
256 if (public->flags & KEY_FLAG_EXT)
257 private = public;
258 else
259 private = key_load_private_type(KEY_RSA1, authfile, "", NULL,
260 &perm_ok);
261 if (private == NULL && !options.batch_mode && perm_ok) {
262 snprintf(buf, sizeof(buf),
263 "Enter passphrase for RSA key '%.100s': ", comment);
264 for (i = 0; i < options.number_of_password_prompts; i++) {
265 passphrase = read_passphrase(buf, 0);
266 if (strcmp(passphrase, "") != 0) {
267 private = key_load_private_type(KEY_RSA1,
268 authfile, passphrase, NULL, NULL);
269 quit = 0;
270 } else {
271 debug2("no passphrase given, try next key");
272 quit = 1;
273 }
274 explicit_bzero(passphrase, strlen(passphrase));
275 free(passphrase);
276 if (private != NULL || quit)
277 break;
278 debug2("bad passphrase given, try again...");
279 }
280 }
281 /* We no longer need the comment. */
282 free(comment);
283
284 if (private == NULL) {
285 if (!options.batch_mode && perm_ok)
286 error("Bad passphrase.");
287
288 /* Send a dummy response packet to avoid protocol error. */
289 packet_start(SSH_CMSG_AUTH_RSA_RESPONSE);
290 for (i = 0; i < 16; i++)
291 packet_put_char(0);
292 packet_send();
293 packet_write_wait();
294
295 /* Expect the server to reject it... */
296 packet_read_expect(SSH_SMSG_FAILURE);
297 BN_clear_free(challenge);
298 return 0;
299 }
300
301 /* Compute and send a response to the challenge. */
302 respond_to_rsa_challenge(challenge, private->rsa);
303
304 /* Destroy the private key unless it in external hardware. */
305 if (!(private->flags & KEY_FLAG_EXT))
306 key_free(private);
307
308 /* We no longer need the challenge. */
309 BN_clear_free(challenge);
310
311 /* Wait for response from the server. */
312 type = packet_read();
313 if (type == SSH_SMSG_SUCCESS) {
314 debug("RSA authentication accepted by server.");
315 return 1;
316 }
317 if (type != SSH_SMSG_FAILURE)
318 packet_disconnect("Protocol error waiting RSA auth response: %d", type);
319 debug("RSA authentication refused.");
320 return 0;
321 }
322
323 /*
324 * Tries to authenticate the user using combined rhosts or /etc/hosts.equiv
325 * authentication and RSA host authentication.
326 */
327 static int
try_rhosts_rsa_authentication(const char * local_user,Key * host_key)328 try_rhosts_rsa_authentication(const char *local_user, Key * host_key)
329 {
330 int type;
331 BIGNUM *challenge;
332
333 debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication.");
334
335 /* Tell the server that we are willing to authenticate using this key. */
336 packet_start(SSH_CMSG_AUTH_RHOSTS_RSA);
337 packet_put_cstring(local_user);
338 packet_put_int(BN_num_bits(host_key->rsa->n));
339 packet_put_bignum(host_key->rsa->e);
340 packet_put_bignum(host_key->rsa->n);
341 packet_send();
342 packet_write_wait();
343
344 /* Wait for server's response. */
345 type = packet_read();
346
347 /* The server responds with failure if it doesn't admit our
348 .rhosts authentication or doesn't know our host key. */
349 if (type == SSH_SMSG_FAILURE) {
350 debug("Server refused our rhosts authentication or host key.");
351 return 0;
352 }
353 /* Otherwise, the server should respond with a challenge. */
354 if (type != SSH_SMSG_AUTH_RSA_CHALLENGE)
355 packet_disconnect("Protocol error during RSA authentication: %d", type);
356
357 /* Get the challenge from the packet. */
358 if ((challenge = BN_new()) == NULL)
359 fatal("try_rhosts_rsa_authentication: BN_new failed");
360 packet_get_bignum(challenge);
361 packet_check_eom();
362
363 debug("Received RSA challenge for host key from server.");
364
365 /* Compute a response to the challenge. */
366 respond_to_rsa_challenge(challenge, host_key->rsa);
367
368 /* We no longer need the challenge. */
369 BN_clear_free(challenge);
370
371 /* Wait for response from the server. */
372 type = packet_read();
373 if (type == SSH_SMSG_SUCCESS) {
374 debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server.");
375 return 1;
376 }
377 if (type != SSH_SMSG_FAILURE)
378 packet_disconnect("Protocol error waiting RSA auth response: %d", type);
379 debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused.");
380 return 0;
381 }
382
383 /*
384 * Tries to authenticate with any string-based challenge/response system.
385 * Note that the client code is not tied to s/key or TIS.
386 */
387 static int
try_challenge_response_authentication(void)388 try_challenge_response_authentication(void)
389 {
390 int type, i;
391 u_int clen;
392 char prompt[1024];
393 char *challenge, *response;
394
395 debug("Doing challenge response authentication.");
396
397 for (i = 0; i < options.number_of_password_prompts; i++) {
398 /* request a challenge */
399 packet_start(SSH_CMSG_AUTH_TIS);
400 packet_send();
401 packet_write_wait();
402
403 type = packet_read();
404 if (type != SSH_SMSG_FAILURE &&
405 type != SSH_SMSG_AUTH_TIS_CHALLENGE) {
406 packet_disconnect("Protocol error: got %d in response "
407 "to SSH_CMSG_AUTH_TIS", type);
408 }
409 if (type != SSH_SMSG_AUTH_TIS_CHALLENGE) {
410 debug("No challenge.");
411 return 0;
412 }
413 challenge = packet_get_string(&clen);
414 packet_check_eom();
415 snprintf(prompt, sizeof prompt, "%s%s", challenge,
416 strchr(challenge, '\n') ? "" : "\nResponse: ");
417 free(challenge);
418 if (i != 0)
419 error("Permission denied, please try again.");
420 if (options.cipher == SSH_CIPHER_NONE)
421 logit("WARNING: Encryption is disabled! "
422 "Response will be transmitted in clear text.");
423 response = read_passphrase(prompt, 0);
424 if (strcmp(response, "") == 0) {
425 free(response);
426 break;
427 }
428 packet_start(SSH_CMSG_AUTH_TIS_RESPONSE);
429 ssh_put_password(response);
430 explicit_bzero(response, strlen(response));
431 free(response);
432 packet_send();
433 packet_write_wait();
434 type = packet_read();
435 if (type == SSH_SMSG_SUCCESS)
436 return 1;
437 if (type != SSH_SMSG_FAILURE)
438 packet_disconnect("Protocol error: got %d in response "
439 "to SSH_CMSG_AUTH_TIS_RESPONSE", type);
440 }
441 /* failure */
442 return 0;
443 }
444
445 /*
446 * Tries to authenticate with plain passwd authentication.
447 */
448 static int
try_password_authentication(char * prompt)449 try_password_authentication(char *prompt)
450 {
451 int type, i;
452 char *password;
453
454 debug("Doing password authentication.");
455 if (options.cipher == SSH_CIPHER_NONE)
456 logit("WARNING: Encryption is disabled! Password will be transmitted in clear text.");
457 for (i = 0; i < options.number_of_password_prompts; i++) {
458 if (i != 0)
459 error("Permission denied, please try again.");
460 password = read_passphrase(prompt, 0);
461 packet_start(SSH_CMSG_AUTH_PASSWORD);
462 ssh_put_password(password);
463 explicit_bzero(password, strlen(password));
464 free(password);
465 packet_send();
466 packet_write_wait();
467
468 type = packet_read();
469 if (type == SSH_SMSG_SUCCESS)
470 return 1;
471 if (type != SSH_SMSG_FAILURE)
472 packet_disconnect("Protocol error: got %d in response to passwd auth", type);
473 }
474 /* failure */
475 return 0;
476 }
477
478 /*
479 * SSH1 key exchange
480 */
481 void
ssh_kex(char * host,struct sockaddr * hostaddr)482 ssh_kex(char *host, struct sockaddr *hostaddr)
483 {
484 int i;
485 BIGNUM *key;
486 Key *host_key, *server_key;
487 int bits, rbits;
488 int ssh_cipher_default = SSH_CIPHER_3DES;
489 u_char session_key[SSH_SESSION_KEY_LENGTH];
490 u_char cookie[8];
491 u_int supported_ciphers;
492 u_int server_flags, client_flags;
493 u_int32_t rnd = 0;
494
495 debug("Waiting for server public key.");
496
497 /* Wait for a public key packet from the server. */
498 packet_read_expect(SSH_SMSG_PUBLIC_KEY);
499
500 /* Get cookie from the packet. */
501 for (i = 0; i < 8; i++)
502 cookie[i] = packet_get_char();
503
504 /* Get the public key. */
505 server_key = key_new(KEY_RSA1);
506 bits = packet_get_int();
507 packet_get_bignum(server_key->rsa->e);
508 packet_get_bignum(server_key->rsa->n);
509
510 rbits = BN_num_bits(server_key->rsa->n);
511 if (bits != rbits) {
512 logit("Warning: Server lies about size of server public key: "
513 "actual size is %d bits vs. announced %d.", rbits, bits);
514 logit("Warning: This may be due to an old implementation of ssh.");
515 }
516 /* Get the host key. */
517 host_key = key_new(KEY_RSA1);
518 bits = packet_get_int();
519 packet_get_bignum(host_key->rsa->e);
520 packet_get_bignum(host_key->rsa->n);
521
522 rbits = BN_num_bits(host_key->rsa->n);
523 if (bits != rbits) {
524 logit("Warning: Server lies about size of server host key: "
525 "actual size is %d bits vs. announced %d.", rbits, bits);
526 logit("Warning: This may be due to an old implementation of ssh.");
527 }
528
529 /* Get protocol flags. */
530 server_flags = packet_get_int();
531 packet_set_protocol_flags(server_flags);
532
533 supported_ciphers = packet_get_int();
534 supported_authentications = packet_get_int();
535 packet_check_eom();
536
537 debug("Received server public key (%d bits) and host key (%d bits).",
538 BN_num_bits(server_key->rsa->n), BN_num_bits(host_key->rsa->n));
539
540 if (verify_host_key(host, hostaddr, host_key) == -1)
541 fatal("Host key verification failed.");
542
543 client_flags = SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN;
544
545 derive_ssh1_session_id(host_key->rsa->n, server_key->rsa->n, cookie, session_id);
546
547 /*
548 * Generate an encryption key for the session. The key is a 256 bit
549 * random number, interpreted as a 32-byte key, with the least
550 * significant 8 bits being the first byte of the key.
551 */
552 for (i = 0; i < 32; i++) {
553 if (i % 4 == 0)
554 rnd = arc4random();
555 session_key[i] = rnd & 0xff;
556 rnd >>= 8;
557 }
558
559 /*
560 * According to the protocol spec, the first byte of the session key
561 * is the highest byte of the integer. The session key is xored with
562 * the first 16 bytes of the session id.
563 */
564 if ((key = BN_new()) == NULL)
565 fatal("ssh_kex: BN_new failed");
566 if (BN_set_word(key, 0) == 0)
567 fatal("ssh_kex: BN_set_word failed");
568 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
569 if (BN_lshift(key, key, 8) == 0)
570 fatal("ssh_kex: BN_lshift failed");
571 if (i < 16) {
572 if (BN_add_word(key, session_key[i] ^ session_id[i])
573 == 0)
574 fatal("ssh_kex: BN_add_word failed");
575 } else {
576 if (BN_add_word(key, session_key[i]) == 0)
577 fatal("ssh_kex: BN_add_word failed");
578 }
579 }
580
581 /*
582 * Encrypt the integer using the public key and host key of the
583 * server (key with smaller modulus first).
584 */
585 if (BN_cmp(server_key->rsa->n, host_key->rsa->n) < 0) {
586 /* Public key has smaller modulus. */
587 if (BN_num_bits(host_key->rsa->n) <
588 BN_num_bits(server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
589 fatal("respond_to_rsa_challenge: host_key %d < server_key %d + "
590 "SSH_KEY_BITS_RESERVED %d",
591 BN_num_bits(host_key->rsa->n),
592 BN_num_bits(server_key->rsa->n),
593 SSH_KEY_BITS_RESERVED);
594 }
595 rsa_public_encrypt(key, key, server_key->rsa);
596 rsa_public_encrypt(key, key, host_key->rsa);
597 } else {
598 /* Host key has smaller modulus (or they are equal). */
599 if (BN_num_bits(server_key->rsa->n) <
600 BN_num_bits(host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
601 fatal("respond_to_rsa_challenge: server_key %d < host_key %d + "
602 "SSH_KEY_BITS_RESERVED %d",
603 BN_num_bits(server_key->rsa->n),
604 BN_num_bits(host_key->rsa->n),
605 SSH_KEY_BITS_RESERVED);
606 }
607 rsa_public_encrypt(key, key, host_key->rsa);
608 rsa_public_encrypt(key, key, server_key->rsa);
609 }
610
611 /* Destroy the public keys since we no longer need them. */
612 key_free(server_key);
613 key_free(host_key);
614
615 if (options.cipher == SSH_CIPHER_NOT_SET) {
616 if (cipher_mask_ssh1(1) & supported_ciphers & (1 << ssh_cipher_default))
617 options.cipher = ssh_cipher_default;
618 } else if (options.cipher == SSH_CIPHER_INVALID ||
619 !(cipher_mask_ssh1(1) & (1 << options.cipher))) {
620 logit("No valid SSH1 cipher, using %.100s instead.",
621 cipher_name(ssh_cipher_default));
622 options.cipher = ssh_cipher_default;
623 }
624 /* Check that the selected cipher is supported. */
625 if (!(supported_ciphers & (1 << options.cipher)))
626 fatal("Selected cipher type %.100s not supported by server.",
627 cipher_name(options.cipher));
628
629 debug("Encryption type: %.100s", cipher_name(options.cipher));
630
631 /* Send the encrypted session key to the server. */
632 packet_start(SSH_CMSG_SESSION_KEY);
633 packet_put_char(options.cipher);
634
635 /* Send the cookie back to the server. */
636 for (i = 0; i < 8; i++)
637 packet_put_char(cookie[i]);
638
639 /* Send and destroy the encrypted encryption key integer. */
640 packet_put_bignum(key);
641 BN_clear_free(key);
642
643 /* Send protocol flags. */
644 packet_put_int(client_flags);
645
646 /* Send the packet now. */
647 packet_send();
648 packet_write_wait();
649
650 debug("Sent encrypted session key.");
651
652 /* Set the encryption key. */
653 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, options.cipher);
654
655 /*
656 * We will no longer need the session key here.
657 * Destroy any extra copies.
658 */
659 explicit_bzero(session_key, sizeof(session_key));
660
661 /*
662 * Expect a success message from the server. Note that this message
663 * will be received in encrypted form.
664 */
665 packet_read_expect(SSH_SMSG_SUCCESS);
666
667 debug("Received encrypted confirmation.");
668 }
669
670 /*
671 * Authenticate user
672 */
673 void
ssh_userauth1(const char * local_user,const char * server_user,char * host,Sensitive * sensitive)674 ssh_userauth1(const char *local_user, const char *server_user, char *host,
675 Sensitive *sensitive)
676 {
677 int i, type;
678
679 if (supported_authentications == 0)
680 fatal("ssh_userauth1: server supports no auth methods");
681
682 /* Send the name of the user to log in as on the server. */
683 packet_start(SSH_CMSG_USER);
684 packet_put_cstring(server_user);
685 packet_send();
686 packet_write_wait();
687
688 /*
689 * The server should respond with success if no authentication is
690 * needed (the user has no password). Otherwise the server responds
691 * with failure.
692 */
693 type = packet_read();
694
695 /* check whether the connection was accepted without authentication. */
696 if (type == SSH_SMSG_SUCCESS)
697 goto success;
698 if (type != SSH_SMSG_FAILURE)
699 packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER", type);
700
701 /*
702 * Try .rhosts or /etc/hosts.equiv authentication with RSA host
703 * authentication.
704 */
705 if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) &&
706 options.rhosts_rsa_authentication) {
707 for (i = 0; i < sensitive->nkeys; i++) {
708 if (sensitive->keys[i] != NULL &&
709 sensitive->keys[i]->type == KEY_RSA1 &&
710 try_rhosts_rsa_authentication(local_user,
711 sensitive->keys[i]))
712 goto success;
713 }
714 }
715 /* Try RSA authentication if the server supports it. */
716 if ((supported_authentications & (1 << SSH_AUTH_RSA)) &&
717 options.rsa_authentication) {
718 /*
719 * Try RSA authentication using the authentication agent. The
720 * agent is tried first because no passphrase is needed for
721 * it, whereas identity files may require passphrases.
722 */
723 if (try_agent_authentication())
724 goto success;
725
726 /* Try RSA authentication for each identity. */
727 for (i = 0; i < options.num_identity_files; i++)
728 if (options.identity_keys[i] != NULL &&
729 options.identity_keys[i]->type == KEY_RSA1 &&
730 try_rsa_authentication(i))
731 goto success;
732 }
733 /* Try challenge response authentication if the server supports it. */
734 if ((supported_authentications & (1 << SSH_AUTH_TIS)) &&
735 options.challenge_response_authentication && !options.batch_mode) {
736 if (try_challenge_response_authentication())
737 goto success;
738 }
739 /* Try password authentication if the server supports it. */
740 if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) &&
741 options.password_authentication && !options.batch_mode) {
742 char prompt[80];
743
744 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
745 server_user, host);
746 if (try_password_authentication(prompt))
747 goto success;
748 }
749 /* All authentication methods have failed. Exit with an error message. */
750 fatal("Permission denied.");
751 /* NOTREACHED */
752
753 success:
754 return; /* need statement after label */
755 }
756