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3c0ef626 | 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" | |
1e608e42 | 26 | RCSID("$OpenBSD: auth2.c,v 1.85 2002/02/24 19:14:59 markus Exp $"); |
3c0ef626 | 27 | |
28 | #include <openssl/evp.h> | |
29 | ||
30 | #include "ssh2.h" | |
a2d82e42 | 31 | #include "ssh1.h" |
3c0ef626 | 32 | #include "xmalloc.h" |
33 | #include "rsa.h" | |
34 | #include "sshpty.h" | |
35 | #include "packet.h" | |
36 | #include "buffer.h" | |
37 | #include "log.h" | |
38 | #include "servconf.h" | |
39 | #include "compat.h" | |
40 | #include "channels.h" | |
41 | #include "bufaux.h" | |
42 | #include "auth.h" | |
43 | #include "session.h" | |
44 | #include "dispatch.h" | |
45 | #include "key.h" | |
46 | #include "cipher.h" | |
47 | #include "kex.h" | |
48 | #include "pathnames.h" | |
49 | #include "uidswap.h" | |
50 | #include "auth-options.h" | |
51 | #include "misc.h" | |
52 | #include "hostfile.h" | |
53 | #include "canohost.h" | |
54 | #include "match.h" | |
55 | ||
5598e598 | 56 | #ifdef GSSAPI |
57 | #include "ssh-gss.h" | |
7d1d5d37 | 58 | #ifdef GSI |
59 | #include "globus_gss_assist.h" | |
60 | #endif | |
5598e598 | 61 | #endif |
62 | ||
3c0ef626 | 63 | /* import */ |
64 | extern ServerOptions options; | |
65 | extern u_char *session_id2; | |
66 | extern int session_id2_len; | |
67 | ||
68 | static Authctxt *x_authctxt = NULL; | |
69 | static int one = 1; | |
70 | ||
71 | typedef struct Authmethod Authmethod; | |
72 | struct Authmethod { | |
73 | char *name; | |
74 | int (*userauth)(Authctxt *authctxt); | |
75 | int *enabled; | |
76 | }; | |
77 | ||
78 | /* protocol */ | |
79 | ||
1e608e42 | 80 | static void input_service_request(int, u_int32_t, void *); |
81 | static void input_userauth_request(int, u_int32_t, void *); | |
3c0ef626 | 82 | |
83 | /* helper */ | |
84 | static Authmethod *authmethod_lookup(const char *); | |
85 | static char *authmethods_get(void); | |
86 | static int user_key_allowed(struct passwd *, Key *); | |
87 | static int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); | |
88 | ||
89 | /* auth */ | |
90 | static void userauth_banner(void); | |
91 | static int userauth_none(Authctxt *); | |
92 | static int userauth_passwd(Authctxt *); | |
93 | static int userauth_pubkey(Authctxt *); | |
94 | static int userauth_hostbased(Authctxt *); | |
95 | static int userauth_kbdint(Authctxt *); | |
96 | ||
5598e598 | 97 | #ifdef GSSAPI |
98 | int userauth_external(Authctxt *authctxt); | |
99 | int userauth_gssapi(Authctxt *authctxt); | |
100 | #endif | |
101 | ||
3c0ef626 | 102 | Authmethod authmethods[] = { |
103 | {"none", | |
104 | userauth_none, | |
105 | &one}, | |
5598e598 | 106 | #ifdef GSSAPI |
107 | {"external-keyx", | |
108 | userauth_external, | |
109 | &options.gss_authentication}, | |
110 | {"gssapi", | |
111 | userauth_gssapi, | |
112 | &options.gss_authentication}, | |
113 | #endif | |
3c0ef626 | 114 | {"publickey", |
115 | userauth_pubkey, | |
116 | &options.pubkey_authentication}, | |
117 | {"password", | |
118 | userauth_passwd, | |
119 | &options.password_authentication}, | |
120 | {"keyboard-interactive", | |
121 | userauth_kbdint, | |
122 | &options.kbd_interactive_authentication}, | |
123 | {"hostbased", | |
124 | userauth_hostbased, | |
125 | &options.hostbased_authentication}, | |
126 | {NULL, NULL, NULL} | |
127 | }; | |
128 | ||
129 | /* | |
130 | * loop until authctxt->success == TRUE | |
131 | */ | |
132 | ||
133 | void | |
1e608e42 | 134 | do_authentication2(void) |
3c0ef626 | 135 | { |
136 | Authctxt *authctxt = authctxt_new(); | |
137 | ||
138 | x_authctxt = authctxt; /*XXX*/ | |
139 | ||
140 | /* challenge-response is implemented via keyboard interactive */ | |
141 | if (options.challenge_response_authentication) | |
142 | options.kbd_interactive_authentication = 1; | |
143 | if (options.pam_authentication_via_kbd_int) | |
144 | options.kbd_interactive_authentication = 1; | |
145 | ||
1e608e42 | 146 | dispatch_init(&dispatch_protocol_error); |
3c0ef626 | 147 | dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); |
148 | dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); | |
149 | do_authenticated(authctxt); | |
150 | } | |
151 | ||
152 | static void | |
1e608e42 | 153 | input_service_request(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 154 | { |
155 | Authctxt *authctxt = ctxt; | |
156 | u_int len; | |
157 | int accept = 0; | |
158 | char *service = packet_get_string(&len); | |
1e608e42 | 159 | packet_check_eom(); |
3c0ef626 | 160 | |
161 | if (authctxt == NULL) | |
162 | fatal("input_service_request: no authctxt"); | |
163 | ||
164 | if (strcmp(service, "ssh-userauth") == 0) { | |
165 | if (!authctxt->success) { | |
166 | accept = 1; | |
167 | /* now we can handle user-auth requests */ | |
168 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); | |
169 | } | |
170 | } | |
171 | /* XXX all other service requests are denied */ | |
172 | ||
173 | if (accept) { | |
174 | packet_start(SSH2_MSG_SERVICE_ACCEPT); | |
175 | packet_put_cstring(service); | |
176 | packet_send(); | |
177 | packet_write_wait(); | |
178 | } else { | |
179 | debug("bad service request %s", service); | |
180 | packet_disconnect("bad service request %s", service); | |
181 | } | |
182 | xfree(service); | |
183 | } | |
184 | ||
185 | static void | |
1e608e42 | 186 | input_userauth_request(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 187 | { |
188 | Authctxt *authctxt = ctxt; | |
189 | Authmethod *m = NULL; | |
190 | char *user, *service, *method, *style = NULL; | |
191 | int authenticated = 0; | |
192 | ||
193 | if (authctxt == NULL) | |
194 | fatal("input_userauth_request: no authctxt"); | |
195 | ||
196 | user = packet_get_string(NULL); | |
197 | service = packet_get_string(NULL); | |
198 | method = packet_get_string(NULL); | |
73a68d83 | 199 | |
200 | if(strcmp(method,"external-keyx") == 0 && strcmp(user,"") == 0) { | |
201 | char *gridmapped_name = NULL; | |
202 | struct passwd *pw = NULL; | |
203 | ||
73a68d83 | 204 | if(globus_gss_assist_gridmap(gssapi_client_name.value, |
205 | &gridmapped_name) == 0) { | |
206 | user = gridmapped_name; | |
207 | debug("I gridmapped and got %s", user); | |
208 | pw = getpwnam(user); | |
209 | if (pw && allowed_user(pw)) { | |
210 | authctxt->user = user; | |
211 | authctxt->pw = pwcopy(pw); | |
212 | authctxt->valid = 1; | |
213 | } | |
214 | } else { | |
215 | debug("I gridmapped and got null, reverting to %s", authctxt->user); | |
216 | user = authctxt->user; | |
217 | } | |
218 | } | |
219 | ||
3c0ef626 | 220 | debug("userauth-request for user %s service %s method %s", user, service, method); |
221 | debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); | |
222 | ||
223 | if ((style = strchr(user, ':')) != NULL) | |
224 | *style++ = 0; | |
225 | ||
226 | if (authctxt->attempt++ == 0) { | |
227 | /* setup auth context */ | |
228 | struct passwd *pw = NULL; | |
229 | pw = getpwnam(user); | |
230 | if (pw && allowed_user(pw) && strcmp(service, "ssh-connection")==0) { | |
231 | authctxt->pw = pwcopy(pw); | |
232 | authctxt->valid = 1; | |
233 | debug2("input_userauth_request: setting up authctxt for %s", user); | |
234 | #ifdef USE_PAM | |
235 | start_pam(pw->pw_name); | |
236 | #endif | |
237 | } else { | |
238 | log("input_userauth_request: illegal user %s", user); | |
239 | #ifdef USE_PAM | |
240 | start_pam("NOUSER"); | |
241 | #endif | |
242 | } | |
243 | setproctitle("%s", pw ? user : "unknown"); | |
244 | authctxt->user = xstrdup(user); | |
245 | authctxt->service = xstrdup(service); | |
246 | authctxt->style = style ? xstrdup(style) : NULL; | |
247 | } else if (strcmp(user, authctxt->user) != 0 || | |
248 | strcmp(service, authctxt->service) != 0) { | |
249 | packet_disconnect("Change of username or service not allowed: " | |
250 | "(%s,%s) -> (%s,%s)", | |
251 | authctxt->user, authctxt->service, user, service); | |
252 | } | |
253 | /* reset state */ | |
1e608e42 | 254 | auth2_challenge_stop(authctxt); |
5598e598 | 255 | |
256 | #ifdef GSSAPI | |
1e608e42 | 257 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); |
258 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); | |
5598e598 | 259 | #endif |
260 | ||
3c0ef626 | 261 | authctxt->postponed = 0; |
3c0ef626 | 262 | |
263 | /* try to authenticate user */ | |
264 | m = authmethod_lookup(method); | |
265 | if (m != NULL) { | |
266 | debug2("input_userauth_request: try method %s", method); | |
267 | authenticated = m->userauth(authctxt); | |
268 | } | |
269 | userauth_finish(authctxt, authenticated, method); | |
270 | ||
271 | xfree(service); | |
272 | xfree(user); | |
273 | xfree(method); | |
274 | } | |
275 | ||
276 | void | |
277 | userauth_finish(Authctxt *authctxt, int authenticated, char *method) | |
278 | { | |
279 | char *methods; | |
280 | ||
281 | if (!authctxt->valid && authenticated) | |
282 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
283 | authctxt->user); | |
284 | ||
285 | /* Special handling for root */ | |
286 | if (authenticated && authctxt->pw->pw_uid == 0 && | |
287 | !auth_root_allowed(method)) | |
288 | authenticated = 0; | |
289 | ||
290 | #ifdef USE_PAM | |
291 | if (authenticated && authctxt->user && !do_pam_account(authctxt->user, | |
292 | NULL)) | |
293 | authenticated = 0; | |
294 | #endif /* USE_PAM */ | |
295 | ||
296 | /* Log before sending the reply */ | |
a2d82e42 | 297 | if (!compat20) |
298 | auth_log(authctxt, authenticated, method, " ssh1"); | |
299 | else | |
3c0ef626 | 300 | auth_log(authctxt, authenticated, method, " ssh2"); |
301 | ||
302 | if (authctxt->postponed) | |
303 | return; | |
304 | ||
305 | /* XXX todo: check if multiple auth methods are needed */ | |
306 | if (authenticated == 1) { | |
307 | /* turn off userauth */ | |
1e608e42 | 308 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); |
a2d82e42 | 309 | if (!compat20) |
310 | packet_start(SSH_SMSG_SUCCESS); | |
311 | else | |
3c0ef626 | 312 | packet_start(SSH2_MSG_USERAUTH_SUCCESS); |
313 | packet_send(); | |
314 | packet_write_wait(); | |
315 | /* now we can break out */ | |
316 | authctxt->success = 1; | |
317 | } else { | |
318 | if (authctxt->failures++ > AUTH_FAIL_MAX) { | |
319 | #ifdef WITH_AIXAUTHENTICATE | |
320 | loginfailed(authctxt->user, | |
1e608e42 | 321 | get_canonical_hostname(options.verify_reverse_mapping), |
3c0ef626 | 322 | "ssh"); |
323 | #endif /* WITH_AIXAUTHENTICATE */ | |
324 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); | |
325 | } | |
411da244 | 326 | if (!compat20) { |
327 | /* | |
328 | * Break out of the dispatch loop now and go back to | |
329 | * SSH1 code. We need to set the 'success' flag to | |
330 | * break out of the loop. Set the 'postponed' flag to | |
331 | * tell the SSH1 code that authentication failed. The | |
332 | * SSH1 code will handle sending SSH_SMSG_FAILURE. | |
333 | */ | |
334 | authctxt->success = authctxt->postponed = 1; | |
335 | } else { | |
3c0ef626 | 336 | methods = authmethods_get(); |
337 | packet_start(SSH2_MSG_USERAUTH_FAILURE); | |
338 | packet_put_cstring(methods); | |
339 | packet_put_char(0); /* XXX partial success, unused */ | |
340 | packet_send(); | |
341 | packet_write_wait(); | |
342 | xfree(methods); | |
411da244 | 343 | } |
3c0ef626 | 344 | } |
345 | } | |
346 | ||
347 | static void | |
348 | userauth_banner(void) | |
349 | { | |
350 | struct stat st; | |
351 | char *banner = NULL; | |
352 | off_t len, n; | |
353 | int fd; | |
354 | ||
355 | if (options.banner == NULL || (datafellows & SSH_BUG_BANNER)) | |
356 | return; | |
357 | if ((fd = open(options.banner, O_RDONLY)) < 0) | |
358 | return; | |
359 | if (fstat(fd, &st) < 0) | |
360 | goto done; | |
361 | len = st.st_size; | |
362 | banner = xmalloc(len + 1); | |
363 | if ((n = read(fd, banner, len)) < 0) | |
364 | goto done; | |
365 | banner[n] = '\0'; | |
366 | packet_start(SSH2_MSG_USERAUTH_BANNER); | |
367 | packet_put_cstring(banner); | |
368 | packet_put_cstring(""); /* language, unused */ | |
369 | packet_send(); | |
370 | debug("userauth_banner: sent"); | |
371 | done: | |
372 | if (banner) | |
373 | xfree(banner); | |
374 | close(fd); | |
375 | return; | |
376 | } | |
377 | ||
378 | static int | |
379 | userauth_none(Authctxt *authctxt) | |
380 | { | |
381 | /* disable method "none", only allowed one time */ | |
382 | Authmethod *m = authmethod_lookup("none"); | |
383 | if (m != NULL) | |
384 | m->enabled = NULL; | |
1e608e42 | 385 | packet_check_eom(); |
3c0ef626 | 386 | userauth_banner(); |
387 | ||
388 | if (authctxt->valid == 0) | |
389 | return(0); | |
390 | ||
391 | #ifdef HAVE_CYGWIN | |
1e608e42 | 392 | if (check_nt_auth(1, authctxt->pw) == 0) |
3c0ef626 | 393 | return(0); |
394 | #endif | |
395 | #ifdef USE_PAM | |
396 | return auth_pam_password(authctxt->pw, ""); | |
397 | #elif defined(HAVE_OSF_SIA) | |
398 | return 0; | |
399 | #else /* !HAVE_OSF_SIA && !USE_PAM */ | |
400 | return auth_password(authctxt, ""); | |
401 | #endif /* USE_PAM */ | |
402 | } | |
403 | ||
404 | static int | |
405 | userauth_passwd(Authctxt *authctxt) | |
406 | { | |
407 | char *password; | |
408 | int authenticated = 0; | |
409 | int change; | |
410 | u_int len; | |
411 | change = packet_get_char(); | |
412 | if (change) | |
413 | log("password change not supported"); | |
414 | password = packet_get_string(&len); | |
1e608e42 | 415 | packet_check_eom(); |
3c0ef626 | 416 | if (authctxt->valid && |
417 | #ifdef HAVE_CYGWIN | |
1e608e42 | 418 | check_nt_auth(1, authctxt->pw) && |
3c0ef626 | 419 | #endif |
420 | #ifdef USE_PAM | |
421 | auth_pam_password(authctxt->pw, password) == 1) | |
422 | #elif defined(HAVE_OSF_SIA) | |
423 | auth_sia_password(authctxt->user, password) == 1) | |
424 | #else /* !USE_PAM && !HAVE_OSF_SIA */ | |
425 | auth_password(authctxt, password) == 1) | |
426 | #endif /* USE_PAM */ | |
427 | authenticated = 1; | |
428 | memset(password, 0, len); | |
429 | xfree(password); | |
430 | return authenticated; | |
431 | } | |
432 | ||
433 | static int | |
434 | userauth_kbdint(Authctxt *authctxt) | |
435 | { | |
436 | int authenticated = 0; | |
437 | char *lang, *devs; | |
438 | ||
439 | lang = packet_get_string(NULL); | |
440 | devs = packet_get_string(NULL); | |
1e608e42 | 441 | packet_check_eom(); |
3c0ef626 | 442 | |
443 | debug("keyboard-interactive devs %s", devs); | |
444 | ||
445 | if (options.challenge_response_authentication) | |
446 | authenticated = auth2_challenge(authctxt, devs); | |
447 | ||
448 | #ifdef USE_PAM | |
449 | if (authenticated == 0 && options.pam_authentication_via_kbd_int) | |
450 | authenticated = auth2_pam(authctxt); | |
451 | #endif | |
452 | xfree(devs); | |
453 | xfree(lang); | |
454 | #ifdef HAVE_CYGWIN | |
1e608e42 | 455 | if (check_nt_auth(0, authctxt->pw) == 0) |
3c0ef626 | 456 | return(0); |
457 | #endif | |
458 | return authenticated; | |
459 | } | |
460 | ||
461 | static int | |
462 | userauth_pubkey(Authctxt *authctxt) | |
463 | { | |
464 | Buffer b; | |
1e608e42 | 465 | Key *key = NULL; |
466 | char *pkalg; | |
467 | u_char *pkblob, *sig; | |
3c0ef626 | 468 | u_int alen, blen, slen; |
469 | int have_sig, pktype; | |
470 | int authenticated = 0; | |
471 | ||
472 | if (!authctxt->valid) { | |
473 | debug2("userauth_pubkey: disabled because of invalid user"); | |
474 | return 0; | |
475 | } | |
476 | have_sig = packet_get_char(); | |
477 | if (datafellows & SSH_BUG_PKAUTH) { | |
478 | debug2("userauth_pubkey: SSH_BUG_PKAUTH"); | |
479 | /* no explicit pkalg given */ | |
480 | pkblob = packet_get_string(&blen); | |
481 | buffer_init(&b); | |
482 | buffer_append(&b, pkblob, blen); | |
483 | /* so we have to extract the pkalg from the pkblob */ | |
484 | pkalg = buffer_get_string(&b, &alen); | |
485 | buffer_free(&b); | |
486 | } else { | |
487 | pkalg = packet_get_string(&alen); | |
488 | pkblob = packet_get_string(&blen); | |
489 | } | |
490 | pktype = key_type_from_name(pkalg); | |
491 | if (pktype == KEY_UNSPEC) { | |
492 | /* this is perfectly legal */ | |
1e608e42 | 493 | log("userauth_pubkey: unsupported public key algorithm: %s", |
494 | pkalg); | |
495 | goto done; | |
3c0ef626 | 496 | } |
497 | key = key_from_blob(pkblob, blen); | |
1e608e42 | 498 | if (key == NULL) { |
499 | error("userauth_pubkey: cannot decode key: %s", pkalg); | |
500 | goto done; | |
501 | } | |
502 | if (key->type != pktype) { | |
503 | error("userauth_pubkey: type mismatch for decoded key " | |
504 | "(received %d, expected %d)", key->type, pktype); | |
505 | goto done; | |
506 | } | |
507 | if (have_sig) { | |
508 | sig = packet_get_string(&slen); | |
509 | packet_check_eom(); | |
510 | buffer_init(&b); | |
511 | if (datafellows & SSH_OLD_SESSIONID) { | |
512 | buffer_append(&b, session_id2, session_id2_len); | |
513 | } else { | |
514 | buffer_put_string(&b, session_id2, session_id2_len); | |
515 | } | |
516 | /* reconstruct packet */ | |
517 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
518 | buffer_put_cstring(&b, authctxt->user); | |
519 | buffer_put_cstring(&b, | |
520 | datafellows & SSH_BUG_PKSERVICE ? | |
521 | "ssh-userauth" : | |
522 | authctxt->service); | |
523 | if (datafellows & SSH_BUG_PKAUTH) { | |
524 | buffer_put_char(&b, have_sig); | |
525 | } else { | |
526 | buffer_put_cstring(&b, "publickey"); | |
527 | buffer_put_char(&b, have_sig); | |
528 | buffer_put_cstring(&b, pkalg); | |
529 | } | |
530 | buffer_put_string(&b, pkblob, blen); | |
3c0ef626 | 531 | #ifdef DEBUG_PK |
1e608e42 | 532 | buffer_dump(&b); |
3c0ef626 | 533 | #endif |
1e608e42 | 534 | /* test for correct signature */ |
535 | if (user_key_allowed(authctxt->pw, key) && | |
536 | key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1) | |
537 | authenticated = 1; | |
538 | buffer_clear(&b); | |
539 | xfree(sig); | |
540 | } else { | |
541 | debug("test whether pkalg/pkblob are acceptable"); | |
542 | packet_check_eom(); | |
543 | ||
544 | /* XXX fake reply and always send PK_OK ? */ | |
545 | /* | |
546 | * XXX this allows testing whether a user is allowed | |
547 | * to login: if you happen to have a valid pubkey this | |
548 | * message is sent. the message is NEVER sent at all | |
549 | * if a user is not allowed to login. is this an | |
550 | * issue? -markus | |
551 | */ | |
552 | if (user_key_allowed(authctxt->pw, key)) { | |
553 | packet_start(SSH2_MSG_USERAUTH_PK_OK); | |
554 | packet_put_string(pkalg, alen); | |
555 | packet_put_string(pkblob, blen); | |
556 | packet_send(); | |
557 | packet_write_wait(); | |
558 | authctxt->postponed = 1; | |
3c0ef626 | 559 | } |
3c0ef626 | 560 | } |
1e608e42 | 561 | if (authenticated != 1) |
562 | auth_clear_options(); | |
563 | done: | |
3c0ef626 | 564 | debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg); |
1e608e42 | 565 | if (key != NULL) |
566 | key_free(key); | |
3c0ef626 | 567 | xfree(pkalg); |
568 | xfree(pkblob); | |
569 | #ifdef HAVE_CYGWIN | |
1e608e42 | 570 | if (check_nt_auth(0, authctxt->pw) == 0) |
3c0ef626 | 571 | return(0); |
572 | #endif | |
573 | return authenticated; | |
574 | } | |
575 | ||
576 | static int | |
577 | userauth_hostbased(Authctxt *authctxt) | |
578 | { | |
579 | Buffer b; | |
1e608e42 | 580 | Key *key = NULL; |
581 | char *pkalg, *cuser, *chost, *service; | |
582 | u_char *pkblob, *sig; | |
3c0ef626 | 583 | u_int alen, blen, slen; |
584 | int pktype; | |
585 | int authenticated = 0; | |
586 | ||
587 | if (!authctxt->valid) { | |
588 | debug2("userauth_hostbased: disabled because of invalid user"); | |
589 | return 0; | |
590 | } | |
591 | pkalg = packet_get_string(&alen); | |
592 | pkblob = packet_get_string(&blen); | |
593 | chost = packet_get_string(NULL); | |
594 | cuser = packet_get_string(NULL); | |
595 | sig = packet_get_string(&slen); | |
596 | ||
597 | debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d", | |
598 | cuser, chost, pkalg, slen); | |
599 | #ifdef DEBUG_PK | |
600 | debug("signature:"); | |
601 | buffer_init(&b); | |
602 | buffer_append(&b, sig, slen); | |
603 | buffer_dump(&b); | |
604 | buffer_free(&b); | |
605 | #endif | |
606 | pktype = key_type_from_name(pkalg); | |
607 | if (pktype == KEY_UNSPEC) { | |
608 | /* this is perfectly legal */ | |
609 | log("userauth_hostbased: unsupported " | |
610 | "public key algorithm: %s", pkalg); | |
611 | goto done; | |
612 | } | |
613 | key = key_from_blob(pkblob, blen); | |
614 | if (key == NULL) { | |
1e608e42 | 615 | error("userauth_hostbased: cannot decode key: %s", pkalg); |
616 | goto done; | |
617 | } | |
618 | if (key->type != pktype) { | |
619 | error("userauth_hostbased: type mismatch for decoded key " | |
620 | "(received %d, expected %d)", key->type, pktype); | |
3c0ef626 | 621 | goto done; |
622 | } | |
623 | service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : | |
624 | authctxt->service; | |
625 | buffer_init(&b); | |
626 | buffer_put_string(&b, session_id2, session_id2_len); | |
627 | /* reconstruct packet */ | |
628 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
629 | buffer_put_cstring(&b, authctxt->user); | |
630 | buffer_put_cstring(&b, service); | |
631 | buffer_put_cstring(&b, "hostbased"); | |
632 | buffer_put_string(&b, pkalg, alen); | |
633 | buffer_put_string(&b, pkblob, blen); | |
634 | buffer_put_cstring(&b, chost); | |
635 | buffer_put_cstring(&b, cuser); | |
636 | #ifdef DEBUG_PK | |
637 | buffer_dump(&b); | |
638 | #endif | |
639 | /* test for allowed key and correct signature */ | |
640 | if (hostbased_key_allowed(authctxt->pw, cuser, chost, key) && | |
641 | key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1) | |
642 | authenticated = 1; | |
643 | ||
644 | buffer_clear(&b); | |
3c0ef626 | 645 | done: |
646 | debug2("userauth_hostbased: authenticated %d", authenticated); | |
1e608e42 | 647 | if (key != NULL) |
648 | key_free(key); | |
3c0ef626 | 649 | xfree(pkalg); |
650 | xfree(pkblob); | |
651 | xfree(cuser); | |
652 | xfree(chost); | |
653 | xfree(sig); | |
654 | return authenticated; | |
655 | } | |
656 | ||
657 | /* get current user */ | |
658 | ||
659 | struct passwd* | |
660 | auth_get_user(void) | |
661 | { | |
662 | return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL; | |
663 | } | |
664 | ||
665 | #define DELIM "," | |
666 | ||
667 | static char * | |
668 | authmethods_get(void) | |
669 | { | |
670 | Authmethod *method = NULL; | |
1e608e42 | 671 | Buffer b; |
3c0ef626 | 672 | char *list; |
673 | ||
1e608e42 | 674 | buffer_init(&b); |
3c0ef626 | 675 | for (method = authmethods; method->name != NULL; method++) { |
676 | if (strcmp(method->name, "none") == 0) | |
677 | continue; | |
678 | if (method->enabled != NULL && *(method->enabled) != 0) { | |
1e608e42 | 679 | if (buffer_len(&b) > 0) |
680 | buffer_append(&b, ",", 1); | |
681 | buffer_append(&b, method->name, strlen(method->name)); | |
3c0ef626 | 682 | } |
683 | } | |
1e608e42 | 684 | buffer_append(&b, "\0", 1); |
685 | list = xstrdup(buffer_ptr(&b)); | |
686 | buffer_free(&b); | |
3c0ef626 | 687 | return list; |
688 | } | |
689 | ||
690 | static Authmethod * | |
691 | authmethod_lookup(const char *name) | |
692 | { | |
693 | Authmethod *method = NULL; | |
694 | if (name != NULL) | |
695 | for (method = authmethods; method->name != NULL; method++) | |
696 | if (method->enabled != NULL && | |
697 | *(method->enabled) != 0 && | |
698 | strcmp(name, method->name) == 0) | |
699 | return method; | |
700 | debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); | |
701 | return NULL; | |
702 | } | |
703 | ||
704 | /* return 1 if user allows given key */ | |
705 | static int | |
706 | user_key_allowed2(struct passwd *pw, Key *key, char *file) | |
707 | { | |
708 | char line[8192]; | |
709 | int found_key = 0; | |
710 | FILE *f; | |
711 | u_long linenum = 0; | |
712 | struct stat st; | |
713 | Key *found; | |
1e608e42 | 714 | char *fp; |
3c0ef626 | 715 | |
716 | if (pw == NULL) | |
717 | return 0; | |
718 | ||
719 | /* Temporarily use the user's uid. */ | |
720 | temporarily_use_uid(pw); | |
721 | ||
722 | debug("trying public key file %s", file); | |
723 | ||
724 | /* Fail quietly if file does not exist */ | |
725 | if (stat(file, &st) < 0) { | |
726 | /* Restore the privileged uid. */ | |
727 | restore_uid(); | |
728 | return 0; | |
729 | } | |
730 | /* Open the file containing the authorized keys. */ | |
731 | f = fopen(file, "r"); | |
732 | if (!f) { | |
733 | /* Restore the privileged uid. */ | |
734 | restore_uid(); | |
735 | return 0; | |
736 | } | |
737 | if (options.strict_modes && | |
738 | secure_filename(f, file, pw, line, sizeof(line)) != 0) { | |
739 | fclose(f); | |
740 | log("Authentication refused: %s", line); | |
741 | restore_uid(); | |
742 | return 0; | |
743 | } | |
744 | ||
745 | found_key = 0; | |
746 | found = key_new(key->type); | |
747 | ||
748 | while (fgets(line, sizeof(line), f)) { | |
749 | char *cp, *options = NULL; | |
750 | linenum++; | |
751 | /* Skip leading whitespace, empty and comment lines. */ | |
752 | for (cp = line; *cp == ' ' || *cp == '\t'; cp++) | |
753 | ; | |
754 | if (!*cp || *cp == '\n' || *cp == '#') | |
755 | continue; | |
756 | ||
757 | if (key_read(found, &cp) != 1) { | |
758 | /* no key? check if there are options for this key */ | |
759 | int quoted = 0; | |
760 | debug2("user_key_allowed: check options: '%s'", cp); | |
761 | options = cp; | |
762 | for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) { | |
763 | if (*cp == '\\' && cp[1] == '"') | |
764 | cp++; /* Skip both */ | |
765 | else if (*cp == '"') | |
766 | quoted = !quoted; | |
767 | } | |
768 | /* Skip remaining whitespace. */ | |
769 | for (; *cp == ' ' || *cp == '\t'; cp++) | |
770 | ; | |
771 | if (key_read(found, &cp) != 1) { | |
772 | debug2("user_key_allowed: advance: '%s'", cp); | |
773 | /* still no key? advance to next line*/ | |
774 | continue; | |
775 | } | |
776 | } | |
777 | if (key_equal(found, key) && | |
778 | auth_parse_options(pw, options, file, linenum) == 1) { | |
779 | found_key = 1; | |
780 | debug("matching key found: file %s, line %lu", | |
781 | file, linenum); | |
1e608e42 | 782 | fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX); |
783 | verbose("Found matching %s key: %s", | |
784 | key_type(found), fp); | |
785 | xfree(fp); | |
3c0ef626 | 786 | break; |
787 | } | |
788 | } | |
789 | restore_uid(); | |
790 | fclose(f); | |
791 | key_free(found); | |
792 | if (!found_key) | |
793 | debug2("key not found"); | |
794 | return found_key; | |
795 | } | |
796 | ||
797 | /* check whether given key is in .ssh/authorized_keys* */ | |
798 | static int | |
799 | user_key_allowed(struct passwd *pw, Key *key) | |
800 | { | |
801 | int success; | |
802 | char *file; | |
803 | ||
804 | file = authorized_keys_file(pw); | |
805 | success = user_key_allowed2(pw, key, file); | |
806 | xfree(file); | |
807 | if (success) | |
808 | return success; | |
809 | ||
810 | /* try suffix "2" for backward compat, too */ | |
811 | file = authorized_keys_file2(pw); | |
812 | success = user_key_allowed2(pw, key, file); | |
813 | xfree(file); | |
814 | return success; | |
815 | } | |
816 | ||
817 | /* return 1 if given hostkey is allowed */ | |
818 | static int | |
819 | hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost, | |
820 | Key *key) | |
821 | { | |
822 | const char *resolvedname, *ipaddr, *lookup; | |
1e608e42 | 823 | HostStatus host_status; |
824 | int len; | |
3c0ef626 | 825 | |
1e608e42 | 826 | resolvedname = get_canonical_hostname(options.verify_reverse_mapping); |
3c0ef626 | 827 | ipaddr = get_remote_ipaddr(); |
828 | ||
829 | debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s", | |
830 | chost, resolvedname, ipaddr); | |
831 | ||
832 | if (options.hostbased_uses_name_from_packet_only) { | |
833 | if (auth_rhosts2(pw, cuser, chost, chost) == 0) | |
834 | return 0; | |
835 | lookup = chost; | |
836 | } else { | |
837 | if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') { | |
838 | debug2("stripping trailing dot from chost %s", chost); | |
839 | chost[len - 1] = '\0'; | |
840 | } | |
841 | if (strcasecmp(resolvedname, chost) != 0) | |
842 | log("userauth_hostbased mismatch: " | |
843 | "client sends %s, but we resolve %s to %s", | |
844 | chost, ipaddr, resolvedname); | |
845 | if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0) | |
846 | return 0; | |
847 | lookup = resolvedname; | |
848 | } | |
849 | debug2("userauth_hostbased: access allowed by auth_rhosts2"); | |
850 | ||
851 | host_status = check_key_in_hostfiles(pw, key, lookup, | |
852 | _PATH_SSH_SYSTEM_HOSTFILE, | |
853 | options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE); | |
854 | ||
855 | /* backward compat if no key has been found. */ | |
856 | if (host_status == HOST_NEW) | |
857 | host_status = check_key_in_hostfiles(pw, key, lookup, | |
858 | _PATH_SSH_SYSTEM_HOSTFILE2, | |
859 | options.ignore_user_known_hosts ? NULL : | |
860 | _PATH_SSH_USER_HOSTFILE2); | |
861 | ||
862 | return (host_status == HOST_OK); | |
863 | } |