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1 | /* | |
2 | * Copyright (c) 2000 Markus Friedl. All rights reserved. | |
3 | * | |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
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 | * | |
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
23 | */ | |
24 | ||
25 | #include "includes.h" | |
26 | RCSID("$OpenBSD: sshconnect2.c,v 1.84 2001/10/29 19:27:15 markus Exp $"); | |
27 | ||
28 | #include <openssl/bn.h> | |
29 | #include <openssl/md5.h> | |
30 | #include <openssl/dh.h> | |
31 | #include <openssl/hmac.h> | |
32 | ||
33 | #include "ssh.h" | |
34 | #include "ssh2.h" | |
35 | #include "xmalloc.h" | |
36 | #include "rsa.h" | |
37 | #include "buffer.h" | |
38 | #include "packet.h" | |
39 | #include "uidswap.h" | |
40 | #include "compat.h" | |
41 | #include "bufaux.h" | |
42 | #include "cipher.h" | |
43 | #include "kex.h" | |
44 | #include "myproposal.h" | |
45 | #include "key.h" | |
46 | #include "sshconnect.h" | |
47 | #include "authfile.h" | |
48 | #include "dh.h" | |
49 | #include "authfd.h" | |
50 | #include "log.h" | |
51 | #include "readconf.h" | |
52 | #include "readpass.h" | |
53 | #include "match.h" | |
54 | #include "dispatch.h" | |
55 | #include "canohost.h" | |
56 | ||
57 | /* import */ | |
58 | extern char *client_version_string; | |
59 | extern char *server_version_string; | |
60 | extern Options options; | |
61 | ||
62 | /* | |
63 | * SSH2 key exchange | |
64 | */ | |
65 | ||
66 | u_char *session_id2 = NULL; | |
67 | int session_id2_len = 0; | |
68 | ||
69 | char *xxx_host; | |
70 | struct sockaddr *xxx_hostaddr; | |
71 | ||
72 | Kex *xxx_kex = NULL; | |
73 | ||
74 | static int | |
75 | verify_host_key_callback(Key *hostkey) | |
76 | { | |
77 | if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1) | |
78 | fatal("Host key verification failed."); | |
79 | return 0; | |
80 | } | |
81 | ||
82 | void | |
83 | ssh_kex2(char *host, struct sockaddr *hostaddr) | |
84 | { | |
85 | Kex *kex; | |
86 | ||
87 | xxx_host = host; | |
88 | xxx_hostaddr = hostaddr; | |
89 | ||
90 | if (options.ciphers == (char *)-1) { | |
91 | log("No valid ciphers for protocol version 2 given, using defaults."); | |
92 | options.ciphers = NULL; | |
93 | } | |
94 | if (options.ciphers != NULL) { | |
95 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
96 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; | |
97 | } | |
98 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
99 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); | |
100 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
101 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); | |
102 | if (options.compression) { | |
103 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
104 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib"; | |
105 | } else { | |
106 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
107 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
108 | } | |
109 | if (options.macs != NULL) { | |
110 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
111 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
112 | } | |
113 | if (options.hostkeyalgorithms != NULL) | |
114 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = | |
115 | options.hostkeyalgorithms; | |
116 | ||
117 | /* start key exchange */ | |
118 | kex = kex_setup(myproposal); | |
119 | kex->client_version_string=client_version_string; | |
120 | kex->server_version_string=server_version_string; | |
121 | kex->verify_host_key=&verify_host_key_callback; | |
122 | ||
123 | xxx_kex = kex; | |
124 | ||
125 | dispatch_run(DISPATCH_BLOCK, &kex->done, kex); | |
126 | ||
127 | session_id2 = kex->session_id; | |
128 | session_id2_len = kex->session_id_len; | |
129 | ||
130 | #ifdef DEBUG_KEXDH | |
131 | /* send 1st encrypted/maced/compressed message */ | |
132 | packet_start(SSH2_MSG_IGNORE); | |
133 | packet_put_cstring("markus"); | |
134 | packet_send(); | |
135 | packet_write_wait(); | |
136 | #endif | |
137 | debug("done: ssh_kex2."); | |
138 | } | |
139 | ||
140 | /* | |
141 | * Authenticate user | |
142 | */ | |
143 | ||
144 | typedef struct Authctxt Authctxt; | |
145 | typedef struct Authmethod Authmethod; | |
146 | ||
147 | typedef int sign_cb_fn( | |
148 | Authctxt *authctxt, Key *key, | |
149 | u_char **sigp, int *lenp, u_char *data, int datalen); | |
150 | ||
151 | struct Authctxt { | |
152 | const char *server_user; | |
153 | const char *local_user; | |
154 | const char *host; | |
155 | const char *service; | |
156 | Authmethod *method; | |
157 | int success; | |
158 | char *authlist; | |
159 | /* pubkey */ | |
160 | Key *last_key; | |
161 | sign_cb_fn *last_key_sign; | |
162 | int last_key_hint; | |
163 | AuthenticationConnection *agent; | |
164 | /* hostbased */ | |
165 | Key **keys; | |
166 | int nkeys; | |
167 | /* kbd-interactive */ | |
168 | int info_req_seen; | |
169 | }; | |
170 | struct Authmethod { | |
171 | char *name; /* string to compare against server's list */ | |
172 | int (*userauth)(Authctxt *authctxt); | |
173 | int *enabled; /* flag in option struct that enables method */ | |
174 | int *batch_flag; /* flag in option struct that disables method */ | |
175 | }; | |
176 | ||
177 | void input_userauth_success(int type, int plen, void *ctxt); | |
178 | void input_userauth_failure(int type, int plen, void *ctxt); | |
179 | void input_userauth_banner(int type, int plen, void *ctxt); | |
180 | void input_userauth_error(int type, int plen, void *ctxt); | |
181 | void input_userauth_info_req(int type, int plen, void *ctxt); | |
182 | void input_userauth_pk_ok(int type, int plen, void *ctxt); | |
183 | ||
184 | int userauth_none(Authctxt *authctxt); | |
185 | int userauth_pubkey(Authctxt *authctxt); | |
186 | int userauth_passwd(Authctxt *authctxt); | |
187 | int userauth_kbdint(Authctxt *authctxt); | |
188 | int userauth_hostbased(Authctxt *authctxt); | |
189 | ||
190 | void userauth(Authctxt *authctxt, char *authlist); | |
191 | ||
192 | static int sign_and_send_pubkey(Authctxt *, Key *, sign_cb_fn *); | |
193 | static void clear_auth_state(Authctxt *); | |
194 | ||
195 | static Authmethod *authmethod_get(char *authlist); | |
196 | static Authmethod *authmethod_lookup(const char *name); | |
197 | static char *authmethods_get(void); | |
198 | ||
199 | Authmethod authmethods[] = { | |
200 | {"hostbased", | |
201 | userauth_hostbased, | |
202 | &options.hostbased_authentication, | |
203 | NULL}, | |
204 | {"publickey", | |
205 | userauth_pubkey, | |
206 | &options.pubkey_authentication, | |
207 | NULL}, | |
208 | {"keyboard-interactive", | |
209 | userauth_kbdint, | |
210 | &options.kbd_interactive_authentication, | |
211 | &options.batch_mode}, | |
212 | {"password", | |
213 | userauth_passwd, | |
214 | &options.password_authentication, | |
215 | &options.batch_mode}, | |
216 | {"none", | |
217 | userauth_none, | |
218 | NULL, | |
219 | NULL}, | |
220 | {NULL, NULL, NULL, NULL} | |
221 | }; | |
222 | ||
223 | void | |
224 | ssh_userauth2(const char *local_user, const char *server_user, char *host, | |
225 | Key **keys, int nkeys) | |
226 | { | |
227 | Authctxt authctxt; | |
228 | int type; | |
229 | int plen; | |
230 | ||
231 | if (options.challenge_response_authentication) | |
232 | options.kbd_interactive_authentication = 1; | |
233 | ||
234 | debug("send SSH2_MSG_SERVICE_REQUEST"); | |
235 | packet_start(SSH2_MSG_SERVICE_REQUEST); | |
236 | packet_put_cstring("ssh-userauth"); | |
237 | packet_send(); | |
238 | packet_write_wait(); | |
239 | type = packet_read(&plen); | |
240 | if (type != SSH2_MSG_SERVICE_ACCEPT) { | |
241 | fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type); | |
242 | } | |
243 | if (packet_remaining() > 0) { | |
244 | char *reply = packet_get_string(&plen); | |
245 | debug("service_accept: %s", reply); | |
246 | xfree(reply); | |
247 | } else { | |
248 | debug("buggy server: service_accept w/o service"); | |
249 | } | |
250 | packet_done(); | |
251 | debug("got SSH2_MSG_SERVICE_ACCEPT"); | |
252 | ||
253 | if (options.preferred_authentications == NULL) | |
254 | options.preferred_authentications = authmethods_get(); | |
255 | ||
256 | /* setup authentication context */ | |
257 | memset(&authctxt, 0, sizeof(authctxt)); | |
258 | authctxt.agent = ssh_get_authentication_connection(); | |
259 | authctxt.server_user = server_user; | |
260 | authctxt.local_user = local_user; | |
261 | authctxt.host = host; | |
262 | authctxt.service = "ssh-connection"; /* service name */ | |
263 | authctxt.success = 0; | |
264 | authctxt.method = authmethod_lookup("none"); | |
265 | authctxt.authlist = NULL; | |
266 | authctxt.keys = keys; | |
267 | authctxt.nkeys = nkeys; | |
268 | authctxt.info_req_seen = 0; | |
269 | if (authctxt.method == NULL) | |
270 | fatal("ssh_userauth2: internal error: cannot send userauth none request"); | |
271 | ||
272 | /* initial userauth request */ | |
273 | userauth_none(&authctxt); | |
274 | ||
275 | dispatch_init(&input_userauth_error); | |
276 | dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success); | |
277 | dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure); | |
278 | dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner); | |
279 | dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */ | |
280 | ||
281 | if (authctxt.agent != NULL) | |
282 | ssh_close_authentication_connection(authctxt.agent); | |
283 | ||
284 | debug("ssh-userauth2 successful: method %s", authctxt.method->name); | |
285 | } | |
286 | void | |
287 | userauth(Authctxt *authctxt, char *authlist) | |
288 | { | |
289 | if (authlist == NULL) { | |
290 | authlist = authctxt->authlist; | |
291 | } else { | |
292 | if (authctxt->authlist) | |
293 | xfree(authctxt->authlist); | |
294 | authctxt->authlist = authlist; | |
295 | } | |
296 | for (;;) { | |
297 | Authmethod *method = authmethod_get(authlist); | |
298 | if (method == NULL) | |
299 | fatal("Permission denied (%s).", authlist); | |
300 | authctxt->method = method; | |
301 | if (method->userauth(authctxt) != 0) { | |
302 | debug2("we sent a %s packet, wait for reply", method->name); | |
303 | break; | |
304 | } else { | |
305 | debug2("we did not send a packet, disable method"); | |
306 | method->enabled = NULL; | |
307 | } | |
308 | } | |
309 | } | |
310 | void | |
311 | input_userauth_error(int type, int plen, void *ctxt) | |
312 | { | |
313 | fatal("input_userauth_error: bad message during authentication: " | |
314 | "type %d", type); | |
315 | } | |
316 | void | |
317 | input_userauth_banner(int type, int plen, void *ctxt) | |
318 | { | |
319 | char *msg, *lang; | |
320 | debug3("input_userauth_banner"); | |
321 | msg = packet_get_string(NULL); | |
322 | lang = packet_get_string(NULL); | |
323 | fprintf(stderr, "%s", msg); | |
324 | xfree(msg); | |
325 | xfree(lang); | |
326 | } | |
327 | void | |
328 | input_userauth_success(int type, int plen, void *ctxt) | |
329 | { | |
330 | Authctxt *authctxt = ctxt; | |
331 | if (authctxt == NULL) | |
332 | fatal("input_userauth_success: no authentication context"); | |
333 | if (authctxt->authlist) | |
334 | xfree(authctxt->authlist); | |
335 | clear_auth_state(authctxt); | |
336 | authctxt->success = 1; /* break out */ | |
337 | } | |
338 | void | |
339 | input_userauth_failure(int type, int plen, void *ctxt) | |
340 | { | |
341 | Authctxt *authctxt = ctxt; | |
342 | char *authlist = NULL; | |
343 | int partial; | |
344 | ||
345 | if (authctxt == NULL) | |
346 | fatal("input_userauth_failure: no authentication context"); | |
347 | ||
348 | authlist = packet_get_string(NULL); | |
349 | partial = packet_get_char(); | |
350 | packet_done(); | |
351 | ||
352 | if (partial != 0) | |
353 | log("Authenticated with partial success."); | |
354 | debug("authentications that can continue: %s", authlist); | |
355 | ||
356 | clear_auth_state(authctxt); | |
357 | userauth(authctxt, authlist); | |
358 | } | |
359 | void | |
360 | input_userauth_pk_ok(int type, int plen, void *ctxt) | |
361 | { | |
362 | Authctxt *authctxt = ctxt; | |
363 | Key *key = NULL; | |
364 | Buffer b; | |
365 | int alen, blen, sent = 0; | |
366 | char *pkalg, *pkblob, *fp; | |
367 | ||
368 | if (authctxt == NULL) | |
369 | fatal("input_userauth_pk_ok: no authentication context"); | |
370 | if (datafellows & SSH_BUG_PKOK) { | |
371 | /* this is similar to SSH_BUG_PKAUTH */ | |
372 | debug2("input_userauth_pk_ok: SSH_BUG_PKOK"); | |
373 | pkblob = packet_get_string(&blen); | |
374 | buffer_init(&b); | |
375 | buffer_append(&b, pkblob, blen); | |
376 | pkalg = buffer_get_string(&b, &alen); | |
377 | buffer_free(&b); | |
378 | } else { | |
379 | pkalg = packet_get_string(&alen); | |
380 | pkblob = packet_get_string(&blen); | |
381 | } | |
382 | packet_done(); | |
383 | ||
384 | debug("input_userauth_pk_ok: pkalg %s blen %d lastkey %p hint %d", | |
385 | pkalg, blen, authctxt->last_key, authctxt->last_key_hint); | |
386 | ||
387 | do { | |
388 | if (authctxt->last_key == NULL || | |
389 | authctxt->last_key_sign == NULL) { | |
390 | debug("no last key or no sign cb"); | |
391 | break; | |
392 | } | |
393 | if (key_type_from_name(pkalg) == KEY_UNSPEC) { | |
394 | debug("unknown pkalg %s", pkalg); | |
395 | break; | |
396 | } | |
397 | if ((key = key_from_blob(pkblob, blen)) == NULL) { | |
398 | debug("no key from blob. pkalg %s", pkalg); | |
399 | break; | |
400 | } | |
401 | fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); | |
402 | debug2("input_userauth_pk_ok: fp %s", fp); | |
403 | xfree(fp); | |
404 | if (!key_equal(key, authctxt->last_key)) { | |
405 | debug("key != last_key"); | |
406 | break; | |
407 | } | |
408 | sent = sign_and_send_pubkey(authctxt, key, | |
409 | authctxt->last_key_sign); | |
410 | } while(0); | |
411 | ||
412 | if (key != NULL) | |
413 | key_free(key); | |
414 | xfree(pkalg); | |
415 | xfree(pkblob); | |
416 | ||
417 | /* unregister */ | |
418 | clear_auth_state(authctxt); | |
419 | dispatch_set(SSH2_MSG_USERAUTH_PK_OK, NULL); | |
420 | ||
421 | /* try another method if we did not send a packet*/ | |
422 | if (sent == 0) | |
423 | userauth(authctxt, NULL); | |
424 | ||
425 | } | |
426 | ||
427 | int | |
428 | userauth_none(Authctxt *authctxt) | |
429 | { | |
430 | /* initial userauth request */ | |
431 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
432 | packet_put_cstring(authctxt->server_user); | |
433 | packet_put_cstring(authctxt->service); | |
434 | packet_put_cstring(authctxt->method->name); | |
435 | packet_send(); | |
436 | return 1; | |
437 | } | |
438 | ||
439 | int | |
440 | userauth_passwd(Authctxt *authctxt) | |
441 | { | |
442 | static int attempt = 0; | |
443 | char prompt[80]; | |
444 | char *password; | |
445 | ||
446 | if (attempt++ >= options.number_of_password_prompts) | |
447 | return 0; | |
448 | ||
449 | if(attempt != 1) | |
450 | error("Permission denied, please try again."); | |
451 | ||
452 | snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ", | |
453 | authctxt->server_user, authctxt->host); | |
454 | password = read_passphrase(prompt, 0); | |
455 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
456 | packet_put_cstring(authctxt->server_user); | |
457 | packet_put_cstring(authctxt->service); | |
458 | packet_put_cstring(authctxt->method->name); | |
459 | packet_put_char(0); | |
460 | packet_put_cstring(password); | |
461 | memset(password, 0, strlen(password)); | |
462 | xfree(password); | |
463 | packet_inject_ignore(64); | |
464 | packet_send(); | |
465 | return 1; | |
466 | } | |
467 | ||
468 | static void | |
469 | clear_auth_state(Authctxt *authctxt) | |
470 | { | |
471 | /* XXX clear authentication state */ | |
472 | if (authctxt->last_key != NULL && authctxt->last_key_hint == -1) { | |
473 | debug3("clear_auth_state: key_free %p", authctxt->last_key); | |
474 | key_free(authctxt->last_key); | |
475 | } | |
476 | authctxt->last_key = NULL; | |
477 | authctxt->last_key_hint = -2; | |
478 | authctxt->last_key_sign = NULL; | |
479 | } | |
480 | ||
481 | static int | |
482 | sign_and_send_pubkey(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback) | |
483 | { | |
484 | Buffer b; | |
485 | u_char *blob, *signature; | |
486 | int bloblen, slen; | |
487 | int skip = 0; | |
488 | int ret = -1; | |
489 | int have_sig = 1; | |
490 | ||
491 | debug3("sign_and_send_pubkey"); | |
492 | ||
493 | if (key_to_blob(k, &blob, &bloblen) == 0) { | |
494 | /* we cannot handle this key */ | |
495 | debug3("sign_and_send_pubkey: cannot handle key"); | |
496 | return 0; | |
497 | } | |
498 | /* data to be signed */ | |
499 | buffer_init(&b); | |
500 | if (datafellows & SSH_OLD_SESSIONID) { | |
501 | buffer_append(&b, session_id2, session_id2_len); | |
502 | skip = session_id2_len; | |
503 | } else { | |
504 | buffer_put_string(&b, session_id2, session_id2_len); | |
505 | skip = buffer_len(&b); | |
506 | } | |
507 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
508 | buffer_put_cstring(&b, authctxt->server_user); | |
509 | buffer_put_cstring(&b, | |
510 | datafellows & SSH_BUG_PKSERVICE ? | |
511 | "ssh-userauth" : | |
512 | authctxt->service); | |
513 | if (datafellows & SSH_BUG_PKAUTH) { | |
514 | buffer_put_char(&b, have_sig); | |
515 | } else { | |
516 | buffer_put_cstring(&b, authctxt->method->name); | |
517 | buffer_put_char(&b, have_sig); | |
518 | buffer_put_cstring(&b, key_ssh_name(k)); | |
519 | } | |
520 | buffer_put_string(&b, blob, bloblen); | |
521 | ||
522 | /* generate signature */ | |
523 | ret = (*sign_callback)(authctxt, k, &signature, &slen, | |
524 | buffer_ptr(&b), buffer_len(&b)); | |
525 | if (ret == -1) { | |
526 | xfree(blob); | |
527 | buffer_free(&b); | |
528 | return 0; | |
529 | } | |
530 | #ifdef DEBUG_PK | |
531 | buffer_dump(&b); | |
532 | #endif | |
533 | if (datafellows & SSH_BUG_PKSERVICE) { | |
534 | buffer_clear(&b); | |
535 | buffer_append(&b, session_id2, session_id2_len); | |
536 | skip = session_id2_len; | |
537 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
538 | buffer_put_cstring(&b, authctxt->server_user); | |
539 | buffer_put_cstring(&b, authctxt->service); | |
540 | buffer_put_cstring(&b, authctxt->method->name); | |
541 | buffer_put_char(&b, have_sig); | |
542 | if (!(datafellows & SSH_BUG_PKAUTH)) | |
543 | buffer_put_cstring(&b, key_ssh_name(k)); | |
544 | buffer_put_string(&b, blob, bloblen); | |
545 | } | |
546 | xfree(blob); | |
547 | ||
548 | /* append signature */ | |
549 | buffer_put_string(&b, signature, slen); | |
550 | xfree(signature); | |
551 | ||
552 | /* skip session id and packet type */ | |
553 | if (buffer_len(&b) < skip + 1) | |
554 | fatal("userauth_pubkey: internal error"); | |
555 | buffer_consume(&b, skip + 1); | |
556 | ||
557 | /* put remaining data from buffer into packet */ | |
558 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
559 | packet_put_raw(buffer_ptr(&b), buffer_len(&b)); | |
560 | buffer_free(&b); | |
561 | packet_send(); | |
562 | ||
563 | return 1; | |
564 | } | |
565 | ||
566 | static int | |
567 | send_pubkey_test(Authctxt *authctxt, Key *k, sign_cb_fn *sign_callback, | |
568 | int hint) | |
569 | { | |
570 | u_char *blob; | |
571 | int bloblen, have_sig = 0; | |
572 | ||
573 | debug3("send_pubkey_test"); | |
574 | ||
575 | if (key_to_blob(k, &blob, &bloblen) == 0) { | |
576 | /* we cannot handle this key */ | |
577 | debug3("send_pubkey_test: cannot handle key"); | |
578 | return 0; | |
579 | } | |
580 | /* register callback for USERAUTH_PK_OK message */ | |
581 | authctxt->last_key_sign = sign_callback; | |
582 | authctxt->last_key_hint = hint; | |
583 | authctxt->last_key = k; | |
584 | dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok); | |
585 | ||
586 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
587 | packet_put_cstring(authctxt->server_user); | |
588 | packet_put_cstring(authctxt->service); | |
589 | packet_put_cstring(authctxt->method->name); | |
590 | packet_put_char(have_sig); | |
591 | if (!(datafellows & SSH_BUG_PKAUTH)) | |
592 | packet_put_cstring(key_ssh_name(k)); | |
593 | packet_put_string(blob, bloblen); | |
594 | xfree(blob); | |
595 | packet_send(); | |
596 | return 1; | |
597 | } | |
598 | ||
599 | static Key * | |
600 | load_identity_file(char *filename) | |
601 | { | |
602 | Key *private; | |
603 | char prompt[300], *passphrase; | |
604 | int quit, i; | |
605 | struct stat st; | |
606 | ||
607 | if (stat(filename, &st) < 0) { | |
608 | debug3("no such identity: %s", filename); | |
609 | return NULL; | |
610 | } | |
611 | private = key_load_private_type(KEY_UNSPEC, filename, "", NULL); | |
612 | if (private == NULL) { | |
613 | if (options.batch_mode) | |
614 | return NULL; | |
615 | snprintf(prompt, sizeof prompt, | |
616 | "Enter passphrase for key '%.100s': ", filename); | |
617 | for (i = 0; i < options.number_of_password_prompts; i++) { | |
618 | passphrase = read_passphrase(prompt, 0); | |
619 | if (strcmp(passphrase, "") != 0) { | |
620 | private = key_load_private_type(KEY_UNSPEC, filename, | |
621 | passphrase, NULL); | |
622 | quit = 0; | |
623 | } else { | |
624 | debug2("no passphrase given, try next key"); | |
625 | quit = 1; | |
626 | } | |
627 | memset(passphrase, 0, strlen(passphrase)); | |
628 | xfree(passphrase); | |
629 | if (private != NULL || quit) | |
630 | break; | |
631 | debug2("bad passphrase given, try again..."); | |
632 | } | |
633 | } | |
634 | return private; | |
635 | } | |
636 | ||
637 | static int | |
638 | identity_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, int *lenp, | |
639 | u_char *data, int datalen) | |
640 | { | |
641 | Key *private; | |
642 | int idx, ret; | |
643 | ||
644 | idx = authctxt->last_key_hint; | |
645 | if (idx < 0) | |
646 | return -1; | |
647 | ||
648 | /* private key is stored in external hardware */ | |
649 | if (options.identity_keys[idx]->flags & KEY_FLAG_EXT) | |
650 | return key_sign(options.identity_keys[idx], sigp, lenp, data, datalen); | |
651 | ||
652 | private = load_identity_file(options.identity_files[idx]); | |
653 | if (private == NULL) | |
654 | return -1; | |
655 | ret = key_sign(private, sigp, lenp, data, datalen); | |
656 | key_free(private); | |
657 | return ret; | |
658 | } | |
659 | ||
660 | static int | |
661 | agent_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, int *lenp, | |
662 | u_char *data, int datalen) | |
663 | { | |
664 | return ssh_agent_sign(authctxt->agent, key, sigp, lenp, data, datalen); | |
665 | } | |
666 | ||
667 | static int | |
668 | key_sign_cb(Authctxt *authctxt, Key *key, u_char **sigp, int *lenp, | |
669 | u_char *data, int datalen) | |
670 | { | |
671 | return key_sign(key, sigp, lenp, data, datalen); | |
672 | } | |
673 | ||
674 | static int | |
675 | userauth_pubkey_agent(Authctxt *authctxt) | |
676 | { | |
677 | static int called = 0; | |
678 | int ret = 0; | |
679 | char *comment; | |
680 | Key *k; | |
681 | ||
682 | if (called == 0) { | |
683 | if (ssh_get_num_identities(authctxt->agent, 2) == 0) | |
684 | debug2("userauth_pubkey_agent: no keys at all"); | |
685 | called = 1; | |
686 | } | |
687 | k = ssh_get_next_identity(authctxt->agent, &comment, 2); | |
688 | if (k == NULL) { | |
689 | debug2("userauth_pubkey_agent: no more keys"); | |
690 | } else { | |
691 | debug("userauth_pubkey_agent: testing agent key %s", comment); | |
692 | xfree(comment); | |
693 | ret = send_pubkey_test(authctxt, k, agent_sign_cb, -1); | |
694 | if (ret == 0) | |
695 | key_free(k); | |
696 | } | |
697 | if (ret == 0) | |
698 | debug2("userauth_pubkey_agent: no message sent"); | |
699 | return ret; | |
700 | } | |
701 | ||
702 | int | |
703 | userauth_pubkey(Authctxt *authctxt) | |
704 | { | |
705 | static int idx = 0; | |
706 | int sent = 0; | |
707 | Key *key; | |
708 | char *filename; | |
709 | ||
710 | if (authctxt->agent != NULL) { | |
711 | do { | |
712 | sent = userauth_pubkey_agent(authctxt); | |
713 | } while(!sent && authctxt->agent->howmany > 0); | |
714 | } | |
715 | while (!sent && idx < options.num_identity_files) { | |
716 | key = options.identity_keys[idx]; | |
717 | filename = options.identity_files[idx]; | |
718 | if (key == NULL) { | |
719 | debug("try privkey: %s", filename); | |
720 | key = load_identity_file(filename); | |
721 | if (key != NULL) { | |
722 | sent = sign_and_send_pubkey(authctxt, key, | |
723 | key_sign_cb); | |
724 | key_free(key); | |
725 | } | |
726 | } else if (key->type != KEY_RSA1) { | |
727 | debug("try pubkey: %s", filename); | |
728 | sent = send_pubkey_test(authctxt, key, | |
729 | identity_sign_cb, idx); | |
730 | } | |
731 | idx++; | |
732 | } | |
733 | return sent; | |
734 | } | |
735 | ||
736 | /* | |
737 | * Send userauth request message specifying keyboard-interactive method. | |
738 | */ | |
739 | int | |
740 | userauth_kbdint(Authctxt *authctxt) | |
741 | { | |
742 | static int attempt = 0; | |
743 | ||
744 | if (attempt++ >= options.number_of_password_prompts) | |
745 | return 0; | |
746 | /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */ | |
747 | if (attempt > 1 && !authctxt->info_req_seen) { | |
748 | debug3("userauth_kbdint: disable: no info_req_seen"); | |
749 | dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL); | |
750 | return 0; | |
751 | } | |
752 | ||
753 | debug2("userauth_kbdint"); | |
754 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
755 | packet_put_cstring(authctxt->server_user); | |
756 | packet_put_cstring(authctxt->service); | |
757 | packet_put_cstring(authctxt->method->name); | |
758 | packet_put_cstring(""); /* lang */ | |
759 | packet_put_cstring(options.kbd_interactive_devices ? | |
760 | options.kbd_interactive_devices : ""); | |
761 | packet_send(); | |
762 | ||
763 | dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req); | |
764 | return 1; | |
765 | } | |
766 | ||
767 | /* | |
768 | * parse INFO_REQUEST, prompt user and send INFO_RESPONSE | |
769 | */ | |
770 | void | |
771 | input_userauth_info_req(int type, int plen, void *ctxt) | |
772 | { | |
773 | Authctxt *authctxt = ctxt; | |
774 | char *name, *inst, *lang, *prompt, *response; | |
775 | u_int num_prompts, i; | |
776 | int echo = 0; | |
777 | ||
778 | debug2("input_userauth_info_req"); | |
779 | ||
780 | if (authctxt == NULL) | |
781 | fatal("input_userauth_info_req: no authentication context"); | |
782 | ||
783 | authctxt->info_req_seen = 1; | |
784 | ||
785 | name = packet_get_string(NULL); | |
786 | inst = packet_get_string(NULL); | |
787 | lang = packet_get_string(NULL); | |
788 | if (strlen(name) > 0) | |
789 | log("%s", name); | |
790 | if (strlen(inst) > 0) | |
791 | log("%s", inst); | |
792 | xfree(name); | |
793 | xfree(inst); | |
794 | xfree(lang); | |
795 | ||
796 | num_prompts = packet_get_int(); | |
797 | /* | |
798 | * Begin to build info response packet based on prompts requested. | |
799 | * We commit to providing the correct number of responses, so if | |
800 | * further on we run into a problem that prevents this, we have to | |
801 | * be sure and clean this up and send a correct error response. | |
802 | */ | |
803 | packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE); | |
804 | packet_put_int(num_prompts); | |
805 | ||
806 | debug2("input_userauth_info_req: num_prompts %d", num_prompts); | |
807 | for (i = 0; i < num_prompts; i++) { | |
808 | prompt = packet_get_string(NULL); | |
809 | echo = packet_get_char(); | |
810 | ||
811 | response = read_passphrase(prompt, echo ? RP_ECHO : 0); | |
812 | ||
813 | packet_put_cstring(response); | |
814 | memset(response, 0, strlen(response)); | |
815 | xfree(response); | |
816 | xfree(prompt); | |
817 | } | |
818 | packet_done(); /* done with parsing incoming message. */ | |
819 | ||
820 | packet_inject_ignore(64); | |
821 | packet_send(); | |
822 | } | |
823 | ||
824 | /* | |
825 | * this will be move to an external program (ssh-keysign) ASAP. ssh-keysign | |
826 | * will be setuid-root and the sbit can be removed from /usr/bin/ssh. | |
827 | */ | |
828 | int | |
829 | userauth_hostbased(Authctxt *authctxt) | |
830 | { | |
831 | Key *private = NULL; | |
832 | Buffer b; | |
833 | u_char *signature, *blob; | |
834 | char *chost, *pkalg, *p; | |
835 | const char *service; | |
836 | u_int blen, slen; | |
837 | int ok, i, len, found = 0; | |
838 | ||
839 | /* check for a useful key */ | |
840 | for (i = 0; i < authctxt->nkeys; i++) { | |
841 | private = authctxt->keys[i]; | |
842 | if (private && private->type != KEY_RSA1) { | |
843 | found = 1; | |
844 | /* we take and free the key */ | |
845 | authctxt->keys[i] = NULL; | |
846 | break; | |
847 | } | |
848 | } | |
849 | if (!found) { | |
850 | debug("userauth_hostbased: no more client hostkeys"); | |
851 | return 0; | |
852 | } | |
853 | if (key_to_blob(private, &blob, &blen) == 0) { | |
854 | key_free(private); | |
855 | return 0; | |
856 | } | |
857 | /* figure out a name for the client host */ | |
858 | p = get_local_name(packet_get_connection_in()); | |
859 | if (p == NULL) { | |
860 | error("userauth_hostbased: cannot get local ipaddr/name"); | |
861 | key_free(private); | |
862 | return 0; | |
863 | } | |
864 | len = strlen(p) + 2; | |
865 | chost = xmalloc(len); | |
866 | strlcpy(chost, p, len); | |
867 | strlcat(chost, ".", len); | |
868 | debug2("userauth_hostbased: chost %s", chost); | |
869 | ||
870 | service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : | |
871 | authctxt->service; | |
872 | pkalg = xstrdup(key_ssh_name(private)); | |
873 | buffer_init(&b); | |
874 | /* construct data */ | |
875 | buffer_put_string(&b, session_id2, session_id2_len); | |
876 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
877 | buffer_put_cstring(&b, authctxt->server_user); | |
878 | buffer_put_cstring(&b, service); | |
879 | buffer_put_cstring(&b, authctxt->method->name); | |
880 | buffer_put_cstring(&b, pkalg); | |
881 | buffer_put_string(&b, blob, blen); | |
882 | buffer_put_cstring(&b, chost); | |
883 | buffer_put_cstring(&b, authctxt->local_user); | |
884 | #ifdef DEBUG_PK | |
885 | buffer_dump(&b); | |
886 | #endif | |
887 | ok = key_sign(private, &signature, &slen, buffer_ptr(&b), buffer_len(&b)); | |
888 | key_free(private); | |
889 | buffer_free(&b); | |
890 | if (ok != 0) { | |
891 | error("key_sign failed"); | |
892 | xfree(chost); | |
893 | xfree(pkalg); | |
894 | return 0; | |
895 | } | |
896 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
897 | packet_put_cstring(authctxt->server_user); | |
898 | packet_put_cstring(authctxt->service); | |
899 | packet_put_cstring(authctxt->method->name); | |
900 | packet_put_cstring(pkalg); | |
901 | packet_put_string(blob, blen); | |
902 | packet_put_cstring(chost); | |
903 | packet_put_cstring(authctxt->local_user); | |
904 | packet_put_string(signature, slen); | |
905 | memset(signature, 's', slen); | |
906 | xfree(signature); | |
907 | xfree(chost); | |
908 | xfree(pkalg); | |
909 | ||
910 | packet_send(); | |
911 | return 1; | |
912 | } | |
913 | ||
914 | /* find auth method */ | |
915 | ||
916 | /* | |
917 | * given auth method name, if configurable options permit this method fill | |
918 | * in auth_ident field and return true, otherwise return false. | |
919 | */ | |
920 | static int | |
921 | authmethod_is_enabled(Authmethod *method) | |
922 | { | |
923 | if (method == NULL) | |
924 | return 0; | |
925 | /* return false if options indicate this method is disabled */ | |
926 | if (method->enabled == NULL || *method->enabled == 0) | |
927 | return 0; | |
928 | /* return false if batch mode is enabled but method needs interactive mode */ | |
929 | if (method->batch_flag != NULL && *method->batch_flag != 0) | |
930 | return 0; | |
931 | return 1; | |
932 | } | |
933 | ||
934 | static Authmethod * | |
935 | authmethod_lookup(const char *name) | |
936 | { | |
937 | Authmethod *method = NULL; | |
938 | if (name != NULL) | |
939 | for (method = authmethods; method->name != NULL; method++) | |
940 | if (strcmp(name, method->name) == 0) | |
941 | return method; | |
942 | debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); | |
943 | return NULL; | |
944 | } | |
945 | ||
946 | /* XXX internal state */ | |
947 | static Authmethod *current = NULL; | |
948 | static char *supported = NULL; | |
949 | static char *preferred = NULL; | |
950 | /* | |
951 | * Given the authentication method list sent by the server, return the | |
952 | * next method we should try. If the server initially sends a nil list, | |
953 | * use a built-in default list. | |
954 | */ | |
955 | static Authmethod * | |
956 | authmethod_get(char *authlist) | |
957 | { | |
958 | ||
959 | char *name = NULL; | |
960 | int next; | |
961 | ||
962 | /* Use a suitable default if we're passed a nil list. */ | |
963 | if (authlist == NULL || strlen(authlist) == 0) | |
964 | authlist = options.preferred_authentications; | |
965 | ||
966 | if (supported == NULL || strcmp(authlist, supported) != 0) { | |
967 | debug3("start over, passed a different list %s", authlist); | |
968 | if (supported != NULL) | |
969 | xfree(supported); | |
970 | supported = xstrdup(authlist); | |
971 | preferred = options.preferred_authentications; | |
972 | debug3("preferred %s", preferred); | |
973 | current = NULL; | |
974 | } else if (current != NULL && authmethod_is_enabled(current)) | |
975 | return current; | |
976 | ||
977 | for (;;) { | |
978 | if ((name = match_list(preferred, supported, &next)) == NULL) { | |
979 | debug("no more auth methods to try"); | |
980 | current = NULL; | |
981 | return NULL; | |
982 | } | |
983 | preferred += next; | |
984 | debug3("authmethod_lookup %s", name); | |
985 | debug3("remaining preferred: %s", preferred); | |
986 | if ((current = authmethod_lookup(name)) != NULL && | |
987 | authmethod_is_enabled(current)) { | |
988 | debug3("authmethod_is_enabled %s", name); | |
989 | debug("next auth method to try is %s", name); | |
990 | return current; | |
991 | } | |
992 | } | |
993 | } | |
994 | ||
995 | ||
996 | #define DELIM "," | |
997 | ||
998 | static char * | |
999 | authmethods_get(void) | |
1000 | { | |
1001 | Authmethod *method = NULL; | |
1002 | char buf[1024]; | |
1003 | ||
1004 | buf[0] = '\0'; | |
1005 | for (method = authmethods; method->name != NULL; method++) { | |
1006 | if (authmethod_is_enabled(method)) { | |
1007 | if (buf[0] != '\0') | |
1008 | strlcat(buf, DELIM, sizeof buf); | |
1009 | strlcat(buf, method->name, sizeof buf); | |
1010 | } | |
1011 | } | |
1012 | return xstrdup(buf); | |
1013 | } |