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1 | /* | |
2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * Code to connect to a remote host, and to perform the client side of the | |
6 | * login (authentication) dialog. | |
7 | * | |
8 | * As far as I am concerned, the code I have written for this software | |
9 | * can be used freely for any purpose. Any derived versions of this | |
10 | * software must be clearly marked as such, and if the derived work is | |
11 | * incompatible with the protocol description in the RFC file, it must be | |
12 | * called by a name other than "ssh" or "Secure Shell". | |
13 | */ | |
14 | ||
15 | #include "includes.h" | |
16 | RCSID("$OpenBSD: sshconnect1.c,v 1.52 2002/08/08 13:50:23 aaron Exp $"); | |
17 | ||
18 | #include <openssl/bn.h> | |
19 | #include <openssl/md5.h> | |
20 | ||
21 | #ifdef KRB4 | |
22 | #include <krb.h> | |
23 | #endif | |
24 | #ifdef KRB5 | |
25 | #include <krb5.h> | |
26 | #ifndef HEIMDAL | |
27 | #define krb5_get_err_text(context,code) error_message(code) | |
28 | #endif /* !HEIMDAL */ | |
29 | #endif | |
30 | #ifdef AFS | |
31 | #include <kafs.h> | |
32 | #include "radix.h" | |
33 | #endif | |
34 | ||
35 | #include "ssh.h" | |
36 | #include "ssh1.h" | |
37 | #include "xmalloc.h" | |
38 | #include "rsa.h" | |
39 | #include "buffer.h" | |
40 | #include "packet.h" | |
41 | #include "mpaux.h" | |
42 | #include "uidswap.h" | |
43 | #include "log.h" | |
44 | #include "readconf.h" | |
45 | #include "key.h" | |
46 | #include "authfd.h" | |
47 | #include "sshconnect.h" | |
48 | #include "authfile.h" | |
49 | #include "readpass.h" | |
50 | #include "cipher.h" | |
51 | #include "canohost.h" | |
52 | #include "auth.h" | |
53 | ||
54 | /* Session id for the current session. */ | |
55 | u_char session_id[16]; | |
56 | u_int supported_authentications = 0; | |
57 | ||
58 | extern Options options; | |
59 | extern char *__progname; | |
60 | ||
61 | /* | |
62 | * Checks if the user has an authentication agent, and if so, tries to | |
63 | * authenticate using the agent. | |
64 | */ | |
65 | static int | |
66 | try_agent_authentication(void) | |
67 | { | |
68 | int type; | |
69 | char *comment; | |
70 | AuthenticationConnection *auth; | |
71 | u_char response[16]; | |
72 | u_int i; | |
73 | Key *key; | |
74 | BIGNUM *challenge; | |
75 | ||
76 | /* Get connection to the agent. */ | |
77 | auth = ssh_get_authentication_connection(); | |
78 | if (!auth) | |
79 | return 0; | |
80 | ||
81 | if ((challenge = BN_new()) == NULL) | |
82 | fatal("try_agent_authentication: BN_new failed"); | |
83 | /* Loop through identities served by the agent. */ | |
84 | for (key = ssh_get_first_identity(auth, &comment, 1); | |
85 | key != NULL; | |
86 | key = ssh_get_next_identity(auth, &comment, 1)) { | |
87 | ||
88 | /* Try this identity. */ | |
89 | debug("Trying RSA authentication via agent with '%.100s'", comment); | |
90 | xfree(comment); | |
91 | ||
92 | /* Tell the server that we are willing to authenticate using this key. */ | |
93 | packet_start(SSH_CMSG_AUTH_RSA); | |
94 | packet_put_bignum(key->rsa->n); | |
95 | packet_send(); | |
96 | packet_write_wait(); | |
97 | ||
98 | /* Wait for server's response. */ | |
99 | type = packet_read(); | |
100 | ||
101 | /* The server sends failure if it doesn\'t like our key or | |
102 | does not support RSA authentication. */ | |
103 | if (type == SSH_SMSG_FAILURE) { | |
104 | debug("Server refused our key."); | |
105 | key_free(key); | |
106 | continue; | |
107 | } | |
108 | /* Otherwise it should have sent a challenge. */ | |
109 | if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) | |
110 | packet_disconnect("Protocol error during RSA authentication: %d", | |
111 | type); | |
112 | ||
113 | packet_get_bignum(challenge); | |
114 | packet_check_eom(); | |
115 | ||
116 | debug("Received RSA challenge from server."); | |
117 | ||
118 | /* Ask the agent to decrypt the challenge. */ | |
119 | if (!ssh_decrypt_challenge(auth, key, challenge, session_id, 1, response)) { | |
120 | /* | |
121 | * The agent failed to authenticate this identifier | |
122 | * although it advertised it supports this. Just | |
123 | * return a wrong value. | |
124 | */ | |
125 | log("Authentication agent failed to decrypt challenge."); | |
126 | memset(response, 0, sizeof(response)); | |
127 | } | |
128 | key_free(key); | |
129 | debug("Sending response to RSA challenge."); | |
130 | ||
131 | /* Send the decrypted challenge back to the server. */ | |
132 | packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); | |
133 | for (i = 0; i < 16; i++) | |
134 | packet_put_char(response[i]); | |
135 | packet_send(); | |
136 | packet_write_wait(); | |
137 | ||
138 | /* Wait for response from the server. */ | |
139 | type = packet_read(); | |
140 | ||
141 | /* The server returns success if it accepted the authentication. */ | |
142 | if (type == SSH_SMSG_SUCCESS) { | |
143 | ssh_close_authentication_connection(auth); | |
144 | BN_clear_free(challenge); | |
145 | debug("RSA authentication accepted by server."); | |
146 | return 1; | |
147 | } | |
148 | /* Otherwise it should return failure. */ | |
149 | if (type != SSH_SMSG_FAILURE) | |
150 | packet_disconnect("Protocol error waiting RSA auth response: %d", | |
151 | type); | |
152 | } | |
153 | ssh_close_authentication_connection(auth); | |
154 | BN_clear_free(challenge); | |
155 | debug("RSA authentication using agent refused."); | |
156 | return 0; | |
157 | } | |
158 | ||
159 | /* | |
160 | * Computes the proper response to a RSA challenge, and sends the response to | |
161 | * the server. | |
162 | */ | |
163 | static void | |
164 | respond_to_rsa_challenge(BIGNUM * challenge, RSA * prv) | |
165 | { | |
166 | u_char buf[32], response[16]; | |
167 | MD5_CTX md; | |
168 | int i, len; | |
169 | ||
170 | /* Decrypt the challenge using the private key. */ | |
171 | /* XXX think about Bleichenbacher, too */ | |
172 | if (rsa_private_decrypt(challenge, challenge, prv) <= 0) | |
173 | packet_disconnect( | |
174 | "respond_to_rsa_challenge: rsa_private_decrypt failed"); | |
175 | ||
176 | /* Compute the response. */ | |
177 | /* The response is MD5 of decrypted challenge plus session id. */ | |
178 | len = BN_num_bytes(challenge); | |
179 | if (len <= 0 || len > sizeof(buf)) | |
180 | packet_disconnect( | |
181 | "respond_to_rsa_challenge: bad challenge length %d", len); | |
182 | ||
183 | memset(buf, 0, sizeof(buf)); | |
184 | BN_bn2bin(challenge, buf + sizeof(buf) - len); | |
185 | MD5_Init(&md); | |
186 | MD5_Update(&md, buf, 32); | |
187 | MD5_Update(&md, session_id, 16); | |
188 | MD5_Final(response, &md); | |
189 | ||
190 | debug("Sending response to host key RSA challenge."); | |
191 | ||
192 | /* Send the response back to the server. */ | |
193 | packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); | |
194 | for (i = 0; i < 16; i++) | |
195 | packet_put_char(response[i]); | |
196 | packet_send(); | |
197 | packet_write_wait(); | |
198 | ||
199 | memset(buf, 0, sizeof(buf)); | |
200 | memset(response, 0, sizeof(response)); | |
201 | memset(&md, 0, sizeof(md)); | |
202 | } | |
203 | ||
204 | /* | |
205 | * Checks if the user has authentication file, and if so, tries to authenticate | |
206 | * the user using it. | |
207 | */ | |
208 | static int | |
209 | try_rsa_authentication(int idx) | |
210 | { | |
211 | BIGNUM *challenge; | |
212 | Key *public, *private; | |
213 | char buf[300], *passphrase, *comment, *authfile; | |
214 | int i, type, quit; | |
215 | ||
216 | public = options.identity_keys[idx]; | |
217 | authfile = options.identity_files[idx]; | |
218 | comment = xstrdup(authfile); | |
219 | ||
220 | debug("Trying RSA authentication with key '%.100s'", comment); | |
221 | ||
222 | /* Tell the server that we are willing to authenticate using this key. */ | |
223 | packet_start(SSH_CMSG_AUTH_RSA); | |
224 | packet_put_bignum(public->rsa->n); | |
225 | packet_send(); | |
226 | packet_write_wait(); | |
227 | ||
228 | /* Wait for server's response. */ | |
229 | type = packet_read(); | |
230 | ||
231 | /* | |
232 | * The server responds with failure if it doesn\'t like our key or | |
233 | * doesn\'t support RSA authentication. | |
234 | */ | |
235 | if (type == SSH_SMSG_FAILURE) { | |
236 | debug("Server refused our key."); | |
237 | xfree(comment); | |
238 | return 0; | |
239 | } | |
240 | /* Otherwise, the server should respond with a challenge. */ | |
241 | if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) | |
242 | packet_disconnect("Protocol error during RSA authentication: %d", type); | |
243 | ||
244 | /* Get the challenge from the packet. */ | |
245 | if ((challenge = BN_new()) == NULL) | |
246 | fatal("try_rsa_authentication: BN_new failed"); | |
247 | packet_get_bignum(challenge); | |
248 | packet_check_eom(); | |
249 | ||
250 | debug("Received RSA challenge from server."); | |
251 | ||
252 | /* | |
253 | * If the key is not stored in external hardware, we have to | |
254 | * load the private key. Try first with empty passphrase; if it | |
255 | * fails, ask for a passphrase. | |
256 | */ | |
257 | if (public->flags & KEY_FLAG_EXT) | |
258 | private = public; | |
259 | else | |
260 | private = key_load_private_type(KEY_RSA1, authfile, "", NULL); | |
261 | if (private == NULL && !options.batch_mode) { | |
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); | |
269 | quit = 0; | |
270 | } else { | |
271 | debug2("no passphrase given, try next key"); | |
272 | quit = 1; | |
273 | } | |
274 | memset(passphrase, 0, strlen(passphrase)); | |
275 | xfree(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 | xfree(comment); | |
283 | ||
284 | if (private == NULL) { | |
285 | if (!options.batch_mode) | |
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 | |
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 | #ifdef KRB4 | |
384 | static int | |
385 | try_krb4_authentication(void) | |
386 | { | |
387 | KTEXT_ST auth; /* Kerberos data */ | |
388 | char *reply; | |
389 | char inst[INST_SZ]; | |
390 | char *realm; | |
391 | CREDENTIALS cred; | |
392 | int r, type; | |
393 | socklen_t slen; | |
394 | Key_schedule schedule; | |
395 | u_long checksum, cksum; | |
396 | MSG_DAT msg_data; | |
397 | struct sockaddr_in local, foreign; | |
398 | struct stat st; | |
399 | ||
400 | /* Don't do anything if we don't have any tickets. */ | |
401 | if (stat(tkt_string(), &st) < 0) | |
402 | return 0; | |
403 | ||
404 | strlcpy(inst, (char *)krb_get_phost(get_canonical_hostname(1)), | |
405 | INST_SZ); | |
406 | ||
407 | realm = (char *)krb_realmofhost(get_canonical_hostname(1)); | |
408 | if (!realm) { | |
409 | debug("Kerberos v4: no realm for %s", get_canonical_hostname(1)); | |
410 | return 0; | |
411 | } | |
412 | /* This can really be anything. */ | |
413 | checksum = (u_long)getpid(); | |
414 | ||
415 | r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum); | |
416 | if (r != KSUCCESS) { | |
417 | debug("Kerberos v4 krb_mk_req failed: %s", krb_err_txt[r]); | |
418 | return 0; | |
419 | } | |
420 | /* Get session key to decrypt the server's reply with. */ | |
421 | r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred); | |
422 | if (r != KSUCCESS) { | |
423 | debug("get_cred failed: %s", krb_err_txt[r]); | |
424 | return 0; | |
425 | } | |
426 | des_key_sched((des_cblock *) cred.session, schedule); | |
427 | ||
428 | /* Send authentication info to server. */ | |
429 | packet_start(SSH_CMSG_AUTH_KERBEROS); | |
430 | packet_put_string((char *) auth.dat, auth.length); | |
431 | packet_send(); | |
432 | packet_write_wait(); | |
433 | ||
434 | /* Zero the buffer. */ | |
435 | (void) memset(auth.dat, 0, MAX_KTXT_LEN); | |
436 | ||
437 | slen = sizeof(local); | |
438 | memset(&local, 0, sizeof(local)); | |
439 | if (getsockname(packet_get_connection_in(), | |
440 | (struct sockaddr *)&local, &slen) < 0) | |
441 | debug("getsockname failed: %s", strerror(errno)); | |
442 | ||
443 | slen = sizeof(foreign); | |
444 | memset(&foreign, 0, sizeof(foreign)); | |
445 | if (getpeername(packet_get_connection_in(), | |
446 | (struct sockaddr *)&foreign, &slen) < 0) { | |
447 | debug("getpeername failed: %s", strerror(errno)); | |
448 | fatal_cleanup(); | |
449 | } | |
450 | /* Get server reply. */ | |
451 | type = packet_read(); | |
452 | switch (type) { | |
453 | case SSH_SMSG_FAILURE: | |
454 | /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */ | |
455 | debug("Kerberos v4 authentication failed."); | |
456 | return 0; | |
457 | break; | |
458 | ||
459 | case SSH_SMSG_AUTH_KERBEROS_RESPONSE: | |
460 | /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */ | |
461 | debug("Kerberos v4 authentication accepted."); | |
462 | ||
463 | /* Get server's response. */ | |
464 | reply = packet_get_string((u_int *) &auth.length); | |
465 | if (auth.length >= MAX_KTXT_LEN) | |
466 | fatal("Kerberos v4: Malformed response from server"); | |
467 | memcpy(auth.dat, reply, auth.length); | |
468 | xfree(reply); | |
469 | ||
470 | packet_check_eom(); | |
471 | ||
472 | /* | |
473 | * If his response isn't properly encrypted with the session | |
474 | * key, and the decrypted checksum fails to match, he's | |
475 | * bogus. Bail out. | |
476 | */ | |
477 | r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session, | |
478 | &foreign, &local, &msg_data); | |
479 | if (r != KSUCCESS) { | |
480 | debug("Kerberos v4 krb_rd_priv failed: %s", | |
481 | krb_err_txt[r]); | |
482 | packet_disconnect("Kerberos v4 challenge failed!"); | |
483 | } | |
484 | /* Fetch the (incremented) checksum that we supplied in the request. */ | |
485 | memcpy((char *)&cksum, (char *)msg_data.app_data, | |
486 | sizeof(cksum)); | |
487 | cksum = ntohl(cksum); | |
488 | ||
489 | /* If it matches, we're golden. */ | |
490 | if (cksum == checksum + 1) { | |
491 | debug("Kerberos v4 challenge successful."); | |
492 | return 1; | |
493 | } else | |
494 | packet_disconnect("Kerberos v4 challenge failed!"); | |
495 | break; | |
496 | ||
497 | default: | |
498 | packet_disconnect("Protocol error on Kerberos v4 response: %d", type); | |
499 | } | |
500 | return 0; | |
501 | } | |
502 | ||
503 | #endif /* KRB4 */ | |
504 | ||
505 | #ifdef KRB5 | |
506 | static int | |
507 | try_krb5_authentication(krb5_context *context, krb5_auth_context *auth_context) | |
508 | { | |
509 | krb5_error_code problem; | |
510 | const char *tkfile; | |
511 | struct stat buf; | |
512 | krb5_ccache ccache = NULL; | |
513 | const char *remotehost; | |
514 | krb5_data ap; | |
515 | int type; | |
516 | krb5_ap_rep_enc_part *reply = NULL; | |
517 | int ret; | |
518 | ||
519 | memset(&ap, 0, sizeof(ap)); | |
520 | ||
521 | problem = krb5_init_context(context); | |
522 | if (problem) { | |
523 | debug("Kerberos v5: krb5_init_context failed"); | |
524 | ret = 0; | |
525 | goto out; | |
526 | } | |
527 | ||
528 | problem = krb5_auth_con_init(*context, auth_context); | |
529 | if (problem) { | |
530 | debug("Kerberos v5: krb5_auth_con_init failed"); | |
531 | ret = 0; | |
532 | goto out; | |
533 | } | |
534 | ||
535 | #ifndef HEIMDAL | |
536 | problem = krb5_auth_con_setflags(*context, *auth_context, | |
537 | KRB5_AUTH_CONTEXT_RET_TIME); | |
538 | if (problem) { | |
539 | debug("Keberos v5: krb5_auth_con_setflags failed"); | |
540 | ret = 0; | |
541 | goto out; | |
542 | } | |
543 | #endif | |
544 | ||
545 | tkfile = krb5_cc_default_name(*context); | |
546 | if (strncmp(tkfile, "FILE:", 5) == 0) | |
547 | tkfile += 5; | |
548 | ||
549 | if (stat(tkfile, &buf) == 0 && getuid() != buf.st_uid) { | |
550 | debug("Kerberos v5: could not get default ccache (permission denied)."); | |
551 | ret = 0; | |
552 | goto out; | |
553 | } | |
554 | ||
555 | problem = krb5_cc_default(*context, &ccache); | |
556 | if (problem) { | |
557 | debug("Kerberos v5: krb5_cc_default failed: %s", | |
558 | krb5_get_err_text(*context, problem)); | |
559 | ret = 0; | |
560 | goto out; | |
561 | } | |
562 | ||
563 | remotehost = get_canonical_hostname(1); | |
564 | ||
565 | problem = krb5_mk_req(*context, auth_context, AP_OPTS_MUTUAL_REQUIRED, | |
566 | "host", remotehost, NULL, ccache, &ap); | |
567 | if (problem) { | |
568 | debug("Kerberos v5: krb5_mk_req failed: %s", | |
569 | krb5_get_err_text(*context, problem)); | |
570 | ret = 0; | |
571 | goto out; | |
572 | } | |
573 | ||
574 | packet_start(SSH_CMSG_AUTH_KERBEROS); | |
575 | packet_put_string((char *) ap.data, ap.length); | |
576 | packet_send(); | |
577 | packet_write_wait(); | |
578 | ||
579 | xfree(ap.data); | |
580 | ap.length = 0; | |
581 | ||
582 | type = packet_read(); | |
583 | switch (type) { | |
584 | case SSH_SMSG_FAILURE: | |
585 | /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */ | |
586 | debug("Kerberos v5 authentication failed."); | |
587 | ret = 0; | |
588 | break; | |
589 | ||
590 | case SSH_SMSG_AUTH_KERBEROS_RESPONSE: | |
591 | /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */ | |
592 | debug("Kerberos v5 authentication accepted."); | |
593 | ||
594 | /* Get server's response. */ | |
595 | ap.data = packet_get_string((unsigned int *) &ap.length); | |
596 | packet_check_eom(); | |
597 | /* XXX je to dobre? */ | |
598 | ||
599 | problem = krb5_rd_rep(*context, *auth_context, &ap, &reply); | |
600 | if (problem) { | |
601 | ret = 0; | |
602 | } | |
603 | ret = 1; | |
604 | break; | |
605 | ||
606 | default: | |
607 | packet_disconnect("Protocol error on Kerberos v5 response: %d", | |
608 | type); | |
609 | ret = 0; | |
610 | break; | |
611 | ||
612 | } | |
613 | ||
614 | out: | |
615 | if (ccache != NULL) | |
616 | krb5_cc_close(*context, ccache); | |
617 | if (reply != NULL) | |
618 | krb5_free_ap_rep_enc_part(*context, reply); | |
619 | if (ap.length > 0) | |
620 | #ifdef HEIMDAL | |
621 | krb5_data_free(&ap); | |
622 | #else | |
623 | krb5_free_data_contents(*context, &ap); | |
624 | #endif | |
625 | ||
626 | return (ret); | |
627 | } | |
628 | ||
629 | static void | |
630 | send_krb5_tgt(krb5_context context, krb5_auth_context auth_context) | |
631 | { | |
632 | int fd, type; | |
633 | krb5_error_code problem; | |
634 | krb5_data outbuf; | |
635 | krb5_ccache ccache = NULL; | |
636 | krb5_creds creds; | |
637 | #ifdef HEIMDAL | |
638 | krb5_kdc_flags flags; | |
639 | #else | |
640 | int forwardable; | |
641 | #endif | |
642 | const char *remotehost; | |
643 | ||
644 | memset(&creds, 0, sizeof(creds)); | |
645 | memset(&outbuf, 0, sizeof(outbuf)); | |
646 | ||
647 | fd = packet_get_connection_in(); | |
648 | ||
649 | #ifdef HEIMDAL | |
650 | problem = krb5_auth_con_setaddrs_from_fd(context, auth_context, &fd); | |
651 | #else | |
652 | problem = krb5_auth_con_genaddrs(context, auth_context, fd, | |
653 | KRB5_AUTH_CONTEXT_GENERATE_REMOTE_FULL_ADDR | | |
654 | KRB5_AUTH_CONTEXT_GENERATE_LOCAL_FULL_ADDR); | |
655 | #endif | |
656 | if (problem) | |
657 | goto out; | |
658 | ||
659 | problem = krb5_cc_default(context, &ccache); | |
660 | if (problem) | |
661 | goto out; | |
662 | ||
663 | problem = krb5_cc_get_principal(context, ccache, &creds.client); | |
664 | if (problem) | |
665 | goto out; | |
666 | ||
667 | remotehost = get_canonical_hostname(1); | |
668 | ||
669 | #ifdef HEIMDAL | |
670 | problem = krb5_build_principal(context, &creds.server, | |
671 | strlen(creds.client->realm), creds.client->realm, | |
672 | "krbtgt", creds.client->realm, NULL); | |
673 | #else | |
674 | problem = krb5_build_principal(context, &creds.server, | |
675 | creds.client->realm.length, creds.client->realm.data, | |
676 | "host", remotehost, NULL); | |
677 | #endif | |
678 | if (problem) | |
679 | goto out; | |
680 | ||
681 | creds.times.endtime = 0; | |
682 | ||
683 | #ifdef HEIMDAL | |
684 | flags.i = 0; | |
685 | flags.b.forwarded = 1; | |
686 | flags.b.forwardable = krb5_config_get_bool(context, NULL, | |
687 | "libdefaults", "forwardable", NULL); | |
688 | problem = krb5_get_forwarded_creds(context, auth_context, | |
689 | ccache, flags.i, remotehost, &creds, &outbuf); | |
690 | #else | |
691 | forwardable = 1; | |
692 | problem = krb5_fwd_tgt_creds(context, auth_context, remotehost, | |
693 | creds.client, creds.server, ccache, forwardable, &outbuf); | |
694 | #endif | |
695 | ||
696 | if (problem) | |
697 | goto out; | |
698 | ||
699 | packet_start(SSH_CMSG_HAVE_KERBEROS_TGT); | |
700 | packet_put_string((char *)outbuf.data, outbuf.length); | |
701 | packet_send(); | |
702 | packet_write_wait(); | |
703 | ||
704 | type = packet_read(); | |
705 | ||
706 | if (type == SSH_SMSG_SUCCESS) { | |
707 | char *pname; | |
708 | ||
709 | krb5_unparse_name(context, creds.client, &pname); | |
710 | debug("Kerberos v5 TGT forwarded (%s).", pname); | |
711 | xfree(pname); | |
712 | } else | |
713 | debug("Kerberos v5 TGT forwarding failed."); | |
714 | ||
715 | return; | |
716 | ||
717 | out: | |
718 | if (problem) | |
719 | debug("Kerberos v5 TGT forwarding failed: %s", | |
720 | krb5_get_err_text(context, problem)); | |
721 | if (creds.client) | |
722 | krb5_free_principal(context, creds.client); | |
723 | if (creds.server) | |
724 | krb5_free_principal(context, creds.server); | |
725 | if (ccache) | |
726 | krb5_cc_close(context, ccache); | |
727 | if (outbuf.data) | |
728 | xfree(outbuf.data); | |
729 | } | |
730 | #endif /* KRB5 */ | |
731 | ||
732 | #ifdef AFS | |
733 | static void | |
734 | send_krb4_tgt(void) | |
735 | { | |
736 | CREDENTIALS *creds; | |
737 | struct stat st; | |
738 | char buffer[4096], pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ]; | |
739 | int problem, type; | |
740 | ||
741 | /* Don't do anything if we don't have any tickets. */ | |
742 | if (stat(tkt_string(), &st) < 0) | |
743 | return; | |
744 | ||
745 | creds = xmalloc(sizeof(*creds)); | |
746 | ||
747 | problem = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm); | |
748 | if (problem) | |
749 | goto out; | |
750 | ||
751 | problem = krb_get_cred("krbtgt", prealm, prealm, creds); | |
752 | if (problem) | |
753 | goto out; | |
754 | ||
755 | if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) { | |
756 | problem = RD_AP_EXP; | |
757 | goto out; | |
758 | } | |
759 | creds_to_radix(creds, (u_char *)buffer, sizeof(buffer)); | |
760 | ||
761 | packet_start(SSH_CMSG_HAVE_KERBEROS_TGT); | |
762 | packet_put_cstring(buffer); | |
763 | packet_send(); | |
764 | packet_write_wait(); | |
765 | ||
766 | type = packet_read(); | |
767 | ||
768 | if (type == SSH_SMSG_SUCCESS) | |
769 | debug("Kerberos v4 TGT forwarded (%s%s%s@%s).", | |
770 | creds->pname, creds->pinst[0] ? "." : "", | |
771 | creds->pinst, creds->realm); | |
772 | else | |
773 | debug("Kerberos v4 TGT rejected."); | |
774 | ||
775 | xfree(creds); | |
776 | return; | |
777 | ||
778 | out: | |
779 | debug("Kerberos v4 TGT passing failed: %s", krb_err_txt[problem]); | |
780 | xfree(creds); | |
781 | } | |
782 | ||
783 | static void | |
784 | send_afs_tokens(void) | |
785 | { | |
786 | CREDENTIALS creds; | |
787 | struct ViceIoctl parms; | |
788 | struct ClearToken ct; | |
789 | int i, type, len; | |
790 | char buf[2048], *p, *server_cell; | |
791 | char buffer[8192]; | |
792 | ||
793 | /* Move over ktc_GetToken, here's something leaner. */ | |
794 | for (i = 0; i < 100; i++) { /* just in case */ | |
795 | parms.in = (char *) &i; | |
796 | parms.in_size = sizeof(i); | |
797 | parms.out = buf; | |
798 | parms.out_size = sizeof(buf); | |
799 | if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0) | |
800 | break; | |
801 | p = buf; | |
802 | ||
803 | /* Get secret token. */ | |
804 | memcpy(&creds.ticket_st.length, p, sizeof(u_int)); | |
805 | if (creds.ticket_st.length > MAX_KTXT_LEN) | |
806 | break; | |
807 | p += sizeof(u_int); | |
808 | memcpy(creds.ticket_st.dat, p, creds.ticket_st.length); | |
809 | p += creds.ticket_st.length; | |
810 | ||
811 | /* Get clear token. */ | |
812 | memcpy(&len, p, sizeof(len)); | |
813 | if (len != sizeof(struct ClearToken)) | |
814 | break; | |
815 | p += sizeof(len); | |
816 | memcpy(&ct, p, len); | |
817 | p += len; | |
818 | p += sizeof(len); /* primary flag */ | |
819 | server_cell = p; | |
820 | ||
821 | /* Flesh out our credentials. */ | |
822 | strlcpy(creds.service, "afs", sizeof(creds.service)); | |
823 | creds.instance[0] = '\0'; | |
824 | strlcpy(creds.realm, server_cell, REALM_SZ); | |
825 | memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ); | |
826 | creds.issue_date = ct.BeginTimestamp; | |
827 | creds.lifetime = krb_time_to_life(creds.issue_date, | |
828 | ct.EndTimestamp); | |
829 | creds.kvno = ct.AuthHandle; | |
830 | snprintf(creds.pname, sizeof(creds.pname), "AFS ID %d", ct.ViceId); | |
831 | creds.pinst[0] = '\0'; | |
832 | ||
833 | /* Encode token, ship it off. */ | |
834 | if (creds_to_radix(&creds, (u_char *)buffer, | |
835 | sizeof(buffer)) <= 0) | |
836 | break; | |
837 | packet_start(SSH_CMSG_HAVE_AFS_TOKEN); | |
838 | packet_put_cstring(buffer); | |
839 | packet_send(); | |
840 | packet_write_wait(); | |
841 | ||
842 | /* Roger, Roger. Clearance, Clarence. What's your vector, | |
843 | Victor? */ | |
844 | type = packet_read(); | |
845 | ||
846 | if (type == SSH_SMSG_FAILURE) | |
847 | debug("AFS token for cell %s rejected.", server_cell); | |
848 | else if (type != SSH_SMSG_SUCCESS) | |
849 | packet_disconnect("Protocol error on AFS token response: %d", type); | |
850 | } | |
851 | } | |
852 | ||
853 | #endif /* AFS */ | |
854 | ||
855 | /* | |
856 | * Tries to authenticate with any string-based challenge/response system. | |
857 | * Note that the client code is not tied to s/key or TIS. | |
858 | */ | |
859 | static int | |
860 | try_challenge_response_authentication(void) | |
861 | { | |
862 | int type, i; | |
863 | u_int clen; | |
864 | char prompt[1024]; | |
865 | char *challenge, *response; | |
866 | ||
867 | debug("Doing challenge response authentication."); | |
868 | ||
869 | for (i = 0; i < options.number_of_password_prompts; i++) { | |
870 | /* request a challenge */ | |
871 | packet_start(SSH_CMSG_AUTH_TIS); | |
872 | packet_send(); | |
873 | packet_write_wait(); | |
874 | ||
875 | type = packet_read(); | |
876 | if (type != SSH_SMSG_FAILURE && | |
877 | type != SSH_SMSG_AUTH_TIS_CHALLENGE) { | |
878 | packet_disconnect("Protocol error: got %d in response " | |
879 | "to SSH_CMSG_AUTH_TIS", type); | |
880 | } | |
881 | if (type != SSH_SMSG_AUTH_TIS_CHALLENGE) { | |
882 | debug("No challenge."); | |
883 | return 0; | |
884 | } | |
885 | challenge = packet_get_string(&clen); | |
886 | packet_check_eom(); | |
887 | snprintf(prompt, sizeof prompt, "%s%s", challenge, | |
888 | strchr(challenge, '\n') ? "" : "\nResponse: "); | |
889 | xfree(challenge); | |
890 | if (i != 0) | |
891 | error("Permission denied, please try again."); | |
892 | if (options.cipher == SSH_CIPHER_NONE) | |
893 | log("WARNING: Encryption is disabled! " | |
894 | "Response will be transmitted in clear text."); | |
895 | response = read_passphrase(prompt, 0); | |
896 | if (strcmp(response, "") == 0) { | |
897 | xfree(response); | |
898 | break; | |
899 | } | |
900 | packet_start(SSH_CMSG_AUTH_TIS_RESPONSE); | |
901 | ssh_put_password(response); | |
902 | memset(response, 0, strlen(response)); | |
903 | xfree(response); | |
904 | packet_send(); | |
905 | packet_write_wait(); | |
906 | type = packet_read(); | |
907 | if (type == SSH_SMSG_SUCCESS) | |
908 | return 1; | |
909 | if (type != SSH_SMSG_FAILURE) | |
910 | packet_disconnect("Protocol error: got %d in response " | |
911 | "to SSH_CMSG_AUTH_TIS_RESPONSE", type); | |
912 | } | |
913 | /* failure */ | |
914 | return 0; | |
915 | } | |
916 | ||
917 | /* | |
918 | * Tries to authenticate with plain passwd authentication. | |
919 | */ | |
920 | static int | |
921 | try_password_authentication(char *prompt) | |
922 | { | |
923 | int type, i; | |
924 | char *password; | |
925 | ||
926 | debug("Doing password authentication."); | |
927 | if (options.cipher == SSH_CIPHER_NONE) | |
928 | log("WARNING: Encryption is disabled! Password will be transmitted in clear text."); | |
929 | for (i = 0; i < options.number_of_password_prompts; i++) { | |
930 | if (i != 0) | |
931 | error("Permission denied, please try again."); | |
932 | password = read_passphrase(prompt, 0); | |
933 | packet_start(SSH_CMSG_AUTH_PASSWORD); | |
934 | ssh_put_password(password); | |
935 | memset(password, 0, strlen(password)); | |
936 | xfree(password); | |
937 | packet_send(); | |
938 | packet_write_wait(); | |
939 | ||
940 | type = packet_read(); | |
941 | if (type == SSH_SMSG_SUCCESS) | |
942 | return 1; | |
943 | if (type != SSH_SMSG_FAILURE) | |
944 | packet_disconnect("Protocol error: got %d in response to passwd auth", type); | |
945 | } | |
946 | /* failure */ | |
947 | return 0; | |
948 | } | |
949 | ||
950 | /* | |
951 | * SSH1 key exchange | |
952 | */ | |
953 | void | |
954 | ssh_kex(char *host, struct sockaddr *hostaddr) | |
955 | { | |
956 | int i; | |
957 | BIGNUM *key; | |
958 | Key *host_key, *server_key; | |
959 | int bits, rbits; | |
960 | int ssh_cipher_default = SSH_CIPHER_3DES; | |
961 | u_char session_key[SSH_SESSION_KEY_LENGTH]; | |
962 | u_char cookie[8]; | |
963 | u_int supported_ciphers; | |
964 | u_int server_flags, client_flags; | |
965 | u_int32_t rand = 0; | |
966 | ||
967 | debug("Waiting for server public key."); | |
968 | ||
969 | /* Wait for a public key packet from the server. */ | |
970 | packet_read_expect(SSH_SMSG_PUBLIC_KEY); | |
971 | ||
972 | /* Get cookie from the packet. */ | |
973 | for (i = 0; i < 8; i++) | |
974 | cookie[i] = packet_get_char(); | |
975 | ||
976 | /* Get the public key. */ | |
977 | server_key = key_new(KEY_RSA1); | |
978 | bits = packet_get_int(); | |
979 | packet_get_bignum(server_key->rsa->e); | |
980 | packet_get_bignum(server_key->rsa->n); | |
981 | ||
982 | rbits = BN_num_bits(server_key->rsa->n); | |
983 | if (bits != rbits) { | |
984 | log("Warning: Server lies about size of server public key: " | |
985 | "actual size is %d bits vs. announced %d.", rbits, bits); | |
986 | log("Warning: This may be due to an old implementation of ssh."); | |
987 | } | |
988 | /* Get the host key. */ | |
989 | host_key = key_new(KEY_RSA1); | |
990 | bits = packet_get_int(); | |
991 | packet_get_bignum(host_key->rsa->e); | |
992 | packet_get_bignum(host_key->rsa->n); | |
993 | ||
994 | rbits = BN_num_bits(host_key->rsa->n); | |
995 | if (bits != rbits) { | |
996 | log("Warning: Server lies about size of server host key: " | |
997 | "actual size is %d bits vs. announced %d.", rbits, bits); | |
998 | log("Warning: This may be due to an old implementation of ssh."); | |
999 | } | |
1000 | ||
1001 | /* Get protocol flags. */ | |
1002 | server_flags = packet_get_int(); | |
1003 | packet_set_protocol_flags(server_flags); | |
1004 | ||
1005 | supported_ciphers = packet_get_int(); | |
1006 | supported_authentications = packet_get_int(); | |
1007 | packet_check_eom(); | |
1008 | ||
1009 | debug("Received server public key (%d bits) and host key (%d bits).", | |
1010 | BN_num_bits(server_key->rsa->n), BN_num_bits(host_key->rsa->n)); | |
1011 | ||
1012 | if (verify_host_key(host, hostaddr, host_key) == -1) | |
1013 | fatal("Host key verification failed."); | |
1014 | ||
1015 | client_flags = SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN; | |
1016 | ||
1017 | compute_session_id(session_id, cookie, host_key->rsa->n, server_key->rsa->n); | |
1018 | ||
1019 | /* Generate a session key. */ | |
1020 | arc4random_stir(); | |
1021 | ||
1022 | /* | |
1023 | * Generate an encryption key for the session. The key is a 256 bit | |
1024 | * random number, interpreted as a 32-byte key, with the least | |
1025 | * significant 8 bits being the first byte of the key. | |
1026 | */ | |
1027 | for (i = 0; i < 32; i++) { | |
1028 | if (i % 4 == 0) | |
1029 | rand = arc4random(); | |
1030 | session_key[i] = rand & 0xff; | |
1031 | rand >>= 8; | |
1032 | } | |
1033 | ||
1034 | /* | |
1035 | * According to the protocol spec, the first byte of the session key | |
1036 | * is the highest byte of the integer. The session key is xored with | |
1037 | * the first 16 bytes of the session id. | |
1038 | */ | |
1039 | if ((key = BN_new()) == NULL) | |
1040 | fatal("respond_to_rsa_challenge: BN_new failed"); | |
1041 | BN_set_word(key, 0); | |
1042 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
1043 | BN_lshift(key, key, 8); | |
1044 | if (i < 16) | |
1045 | BN_add_word(key, session_key[i] ^ session_id[i]); | |
1046 | else | |
1047 | BN_add_word(key, session_key[i]); | |
1048 | } | |
1049 | ||
1050 | /* | |
1051 | * Encrypt the integer using the public key and host key of the | |
1052 | * server (key with smaller modulus first). | |
1053 | */ | |
1054 | if (BN_cmp(server_key->rsa->n, host_key->rsa->n) < 0) { | |
1055 | /* Public key has smaller modulus. */ | |
1056 | if (BN_num_bits(host_key->rsa->n) < | |
1057 | BN_num_bits(server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1058 | fatal("respond_to_rsa_challenge: host_key %d < server_key %d + " | |
1059 | "SSH_KEY_BITS_RESERVED %d", | |
1060 | BN_num_bits(host_key->rsa->n), | |
1061 | BN_num_bits(server_key->rsa->n), | |
1062 | SSH_KEY_BITS_RESERVED); | |
1063 | } | |
1064 | rsa_public_encrypt(key, key, server_key->rsa); | |
1065 | rsa_public_encrypt(key, key, host_key->rsa); | |
1066 | } else { | |
1067 | /* Host key has smaller modulus (or they are equal). */ | |
1068 | if (BN_num_bits(server_key->rsa->n) < | |
1069 | BN_num_bits(host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1070 | fatal("respond_to_rsa_challenge: server_key %d < host_key %d + " | |
1071 | "SSH_KEY_BITS_RESERVED %d", | |
1072 | BN_num_bits(server_key->rsa->n), | |
1073 | BN_num_bits(host_key->rsa->n), | |
1074 | SSH_KEY_BITS_RESERVED); | |
1075 | } | |
1076 | rsa_public_encrypt(key, key, host_key->rsa); | |
1077 | rsa_public_encrypt(key, key, server_key->rsa); | |
1078 | } | |
1079 | ||
1080 | /* Destroy the public keys since we no longer need them. */ | |
1081 | key_free(server_key); | |
1082 | key_free(host_key); | |
1083 | ||
1084 | if (options.cipher == SSH_CIPHER_NOT_SET) { | |
1085 | if (cipher_mask_ssh1(1) & supported_ciphers & (1 << ssh_cipher_default)) | |
1086 | options.cipher = ssh_cipher_default; | |
1087 | } else if (options.cipher == SSH_CIPHER_ILLEGAL || | |
1088 | !(cipher_mask_ssh1(1) & (1 << options.cipher))) { | |
1089 | log("No valid SSH1 cipher, using %.100s instead.", | |
1090 | cipher_name(ssh_cipher_default)); | |
1091 | options.cipher = ssh_cipher_default; | |
1092 | } | |
1093 | /* Check that the selected cipher is supported. */ | |
1094 | if (!(supported_ciphers & (1 << options.cipher))) | |
1095 | fatal("Selected cipher type %.100s not supported by server.", | |
1096 | cipher_name(options.cipher)); | |
1097 | ||
1098 | debug("Encryption type: %.100s", cipher_name(options.cipher)); | |
1099 | ||
1100 | /* Send the encrypted session key to the server. */ | |
1101 | packet_start(SSH_CMSG_SESSION_KEY); | |
1102 | packet_put_char(options.cipher); | |
1103 | ||
1104 | /* Send the cookie back to the server. */ | |
1105 | for (i = 0; i < 8; i++) | |
1106 | packet_put_char(cookie[i]); | |
1107 | ||
1108 | /* Send and destroy the encrypted encryption key integer. */ | |
1109 | packet_put_bignum(key); | |
1110 | BN_clear_free(key); | |
1111 | ||
1112 | /* Send protocol flags. */ | |
1113 | packet_put_int(client_flags); | |
1114 | ||
1115 | /* Send the packet now. */ | |
1116 | packet_send(); | |
1117 | packet_write_wait(); | |
1118 | ||
1119 | debug("Sent encrypted session key."); | |
1120 | ||
1121 | /* Set the encryption key. */ | |
1122 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, options.cipher); | |
1123 | ||
1124 | /* We will no longer need the session key here. Destroy any extra copies. */ | |
1125 | memset(session_key, 0, sizeof(session_key)); | |
1126 | ||
1127 | /* | |
1128 | * Expect a success message from the server. Note that this message | |
1129 | * will be received in encrypted form. | |
1130 | */ | |
1131 | packet_read_expect(SSH_SMSG_SUCCESS); | |
1132 | ||
1133 | debug("Received encrypted confirmation."); | |
1134 | } | |
1135 | ||
1136 | /* | |
1137 | * Authenticate user | |
1138 | */ | |
1139 | void | |
1140 | ssh_userauth1(const char *local_user, const char *server_user, char *host, | |
1141 | Sensitive *sensitive) | |
1142 | { | |
1143 | #ifdef KRB5 | |
1144 | krb5_context context = NULL; | |
1145 | krb5_auth_context auth_context = NULL; | |
1146 | #endif | |
1147 | int i, type; | |
1148 | ||
1149 | if (supported_authentications == 0) | |
1150 | fatal("ssh_userauth1: server supports no auth methods"); | |
1151 | ||
1152 | /* Send the name of the user to log in as on the server. */ | |
1153 | packet_start(SSH_CMSG_USER); | |
1154 | packet_put_cstring(server_user); | |
1155 | packet_send(); | |
1156 | packet_write_wait(); | |
1157 | ||
1158 | /* | |
1159 | * The server should respond with success if no authentication is | |
1160 | * needed (the user has no password). Otherwise the server responds | |
1161 | * with failure. | |
1162 | */ | |
1163 | type = packet_read(); | |
1164 | ||
1165 | /* check whether the connection was accepted without authentication. */ | |
1166 | if (type == SSH_SMSG_SUCCESS) | |
1167 | goto success; | |
1168 | if (type != SSH_SMSG_FAILURE) | |
1169 | packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER", type); | |
1170 | ||
1171 | #ifdef KRB5 | |
1172 | if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) && | |
1173 | options.kerberos_authentication) { | |
1174 | debug("Trying Kerberos v5 authentication."); | |
1175 | ||
1176 | if (try_krb5_authentication(&context, &auth_context)) { | |
1177 | type = packet_read(); | |
1178 | if (type == SSH_SMSG_SUCCESS) | |
1179 | goto success; | |
1180 | if (type != SSH_SMSG_FAILURE) | |
1181 | packet_disconnect("Protocol error: got %d in response to Kerberos v5 auth", type); | |
1182 | } | |
1183 | } | |
1184 | #endif /* KRB5 */ | |
1185 | ||
1186 | #ifdef KRB4 | |
1187 | if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) && | |
1188 | options.kerberos_authentication) { | |
1189 | debug("Trying Kerberos v4 authentication."); | |
1190 | ||
1191 | if (try_krb4_authentication()) { | |
1192 | type = packet_read(); | |
1193 | if (type == SSH_SMSG_SUCCESS) | |
1194 | goto success; | |
1195 | if (type != SSH_SMSG_FAILURE) | |
1196 | packet_disconnect("Protocol error: got %d in response to Kerberos v4 auth", type); | |
1197 | } | |
1198 | } | |
1199 | #endif /* KRB4 */ | |
1200 | ||
1201 | /* | |
1202 | * Use rhosts authentication if running in privileged socket and we | |
1203 | * do not wish to remain anonymous. | |
1204 | */ | |
1205 | if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) && | |
1206 | options.rhosts_authentication) { | |
1207 | debug("Trying rhosts authentication."); | |
1208 | packet_start(SSH_CMSG_AUTH_RHOSTS); | |
1209 | packet_put_cstring(local_user); | |
1210 | packet_send(); | |
1211 | packet_write_wait(); | |
1212 | ||
1213 | /* The server should respond with success or failure. */ | |
1214 | type = packet_read(); | |
1215 | if (type == SSH_SMSG_SUCCESS) | |
1216 | goto success; | |
1217 | if (type != SSH_SMSG_FAILURE) | |
1218 | packet_disconnect("Protocol error: got %d in response to rhosts auth", | |
1219 | type); | |
1220 | } | |
1221 | /* | |
1222 | * Try .rhosts or /etc/hosts.equiv authentication with RSA host | |
1223 | * authentication. | |
1224 | */ | |
1225 | if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) && | |
1226 | options.rhosts_rsa_authentication) { | |
1227 | for (i = 0; i < sensitive->nkeys; i++) { | |
1228 | if (sensitive->keys[i] != NULL && | |
1229 | sensitive->keys[i]->type == KEY_RSA1 && | |
1230 | try_rhosts_rsa_authentication(local_user, | |
1231 | sensitive->keys[i])) | |
1232 | goto success; | |
1233 | } | |
1234 | } | |
1235 | /* Try RSA authentication if the server supports it. */ | |
1236 | if ((supported_authentications & (1 << SSH_AUTH_RSA)) && | |
1237 | options.rsa_authentication) { | |
1238 | /* | |
1239 | * Try RSA authentication using the authentication agent. The | |
1240 | * agent is tried first because no passphrase is needed for | |
1241 | * it, whereas identity files may require passphrases. | |
1242 | */ | |
1243 | if (try_agent_authentication()) | |
1244 | goto success; | |
1245 | ||
1246 | /* Try RSA authentication for each identity. */ | |
1247 | for (i = 0; i < options.num_identity_files; i++) | |
1248 | if (options.identity_keys[i] != NULL && | |
1249 | options.identity_keys[i]->type == KEY_RSA1 && | |
1250 | try_rsa_authentication(i)) | |
1251 | goto success; | |
1252 | } | |
1253 | /* Try challenge response authentication if the server supports it. */ | |
1254 | if ((supported_authentications & (1 << SSH_AUTH_TIS)) && | |
1255 | options.challenge_response_authentication && !options.batch_mode) { | |
1256 | if (try_challenge_response_authentication()) | |
1257 | goto success; | |
1258 | } | |
1259 | /* Try password authentication if the server supports it. */ | |
1260 | if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) && | |
1261 | options.password_authentication && !options.batch_mode) { | |
1262 | char prompt[80]; | |
1263 | ||
1264 | snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", | |
1265 | server_user, host); | |
1266 | if (try_password_authentication(prompt)) | |
1267 | goto success; | |
1268 | } | |
1269 | /* All authentication methods have failed. Exit with an error message. */ | |
1270 | fatal("Permission denied."); | |
1271 | /* NOTREACHED */ | |
1272 | ||
1273 | success: | |
1274 | #ifdef KRB5 | |
1275 | /* Try Kerberos v5 TGT passing. */ | |
1276 | if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) && | |
1277 | options.kerberos_tgt_passing && context && auth_context) { | |
1278 | if (options.cipher == SSH_CIPHER_NONE) | |
1279 | log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!"); | |
1280 | send_krb5_tgt(context, auth_context); | |
1281 | } | |
1282 | if (auth_context) | |
1283 | krb5_auth_con_free(context, auth_context); | |
1284 | if (context) | |
1285 | krb5_free_context(context); | |
1286 | #endif | |
1287 | ||
1288 | #ifdef AFS | |
1289 | /* Try Kerberos v4 TGT passing if the server supports it. */ | |
1290 | if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) && | |
1291 | options.kerberos_tgt_passing) { | |
1292 | if (options.cipher == SSH_CIPHER_NONE) | |
1293 | log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!"); | |
1294 | send_krb4_tgt(); | |
1295 | } | |
1296 | /* Try AFS token passing if the server supports it. */ | |
1297 | if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) && | |
1298 | options.afs_token_passing && k_hasafs()) { | |
1299 | if (options.cipher == SSH_CIPHER_NONE) | |
1300 | log("WARNING: Encryption is disabled! Token will be transmitted in the clear!"); | |
1301 | send_afs_tokens(); | |
1302 | } | |
1303 | #endif /* AFS */ | |
1304 | ||
1305 | return; /* need statement after label */ | |
1306 | } |