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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" | |
26 | RCSID("$OpenBSD: auth2.c,v 1.72 2001/11/07 22:41:51 markus Exp $"); | |
27 | ||
28 | #include <openssl/evp.h> | |
29 | ||
30 | #include "ssh2.h" | |
31 | #include "xmalloc.h" | |
32 | #include "rsa.h" | |
33 | #include "sshpty.h" | |
34 | #include "packet.h" | |
35 | #include "buffer.h" | |
36 | #include "log.h" | |
37 | #include "servconf.h" | |
38 | #include "compat.h" | |
39 | #include "channels.h" | |
40 | #include "bufaux.h" | |
41 | #include "auth.h" | |
42 | #include "session.h" | |
43 | #include "dispatch.h" | |
44 | #include "key.h" | |
45 | #include "cipher.h" | |
46 | #include "kex.h" | |
47 | #include "pathnames.h" | |
48 | #include "uidswap.h" | |
49 | #include "auth-options.h" | |
50 | #include "misc.h" | |
51 | #include "hostfile.h" | |
52 | #include "canohost.h" | |
53 | #include "match.h" | |
54 | ||
55 | /* import */ | |
56 | extern ServerOptions options; | |
57 | extern u_char *session_id2; | |
58 | extern int session_id2_len; | |
59 | ||
60 | static Authctxt *x_authctxt = NULL; | |
61 | static int one = 1; | |
62 | ||
63 | typedef struct Authmethod Authmethod; | |
64 | struct Authmethod { | |
65 | char *name; | |
66 | int (*userauth)(Authctxt *authctxt); | |
67 | int *enabled; | |
68 | }; | |
69 | ||
70 | /* protocol */ | |
71 | ||
72 | static void input_service_request(int, int, void *); | |
73 | static void input_userauth_request(int, int, void *); | |
74 | static void protocol_error(int, int, void *); | |
75 | ||
76 | /* helper */ | |
77 | static Authmethod *authmethod_lookup(const char *); | |
78 | static char *authmethods_get(void); | |
79 | static int user_key_allowed(struct passwd *, Key *); | |
80 | static int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); | |
81 | ||
82 | /* auth */ | |
83 | static void userauth_banner(void); | |
84 | static int userauth_none(Authctxt *); | |
85 | static int userauth_passwd(Authctxt *); | |
86 | static int userauth_pubkey(Authctxt *); | |
87 | static int userauth_hostbased(Authctxt *); | |
88 | static int userauth_kbdint(Authctxt *); | |
89 | ||
90 | Authmethod authmethods[] = { | |
91 | {"none", | |
92 | userauth_none, | |
93 | &one}, | |
94 | {"publickey", | |
95 | userauth_pubkey, | |
96 | &options.pubkey_authentication}, | |
97 | {"password", | |
98 | userauth_passwd, | |
99 | &options.password_authentication}, | |
100 | {"keyboard-interactive", | |
101 | userauth_kbdint, | |
102 | &options.kbd_interactive_authentication}, | |
103 | {"hostbased", | |
104 | userauth_hostbased, | |
105 | &options.hostbased_authentication}, | |
106 | {NULL, NULL, NULL} | |
107 | }; | |
108 | ||
109 | /* | |
110 | * loop until authctxt->success == TRUE | |
111 | */ | |
112 | ||
113 | void | |
114 | do_authentication2() | |
115 | { | |
116 | Authctxt *authctxt = authctxt_new(); | |
117 | ||
118 | x_authctxt = authctxt; /*XXX*/ | |
119 | ||
120 | /* challenge-response is implemented via keyboard interactive */ | |
121 | if (options.challenge_response_authentication) | |
122 | options.kbd_interactive_authentication = 1; | |
123 | if (options.pam_authentication_via_kbd_int) | |
124 | options.kbd_interactive_authentication = 1; | |
125 | ||
126 | dispatch_init(&protocol_error); | |
127 | dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); | |
128 | dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); | |
129 | do_authenticated(authctxt); | |
130 | } | |
131 | ||
132 | static void | |
133 | protocol_error(int type, int plen, void *ctxt) | |
134 | { | |
135 | log("auth: protocol error: type %d plen %d", type, plen); | |
136 | packet_start(SSH2_MSG_UNIMPLEMENTED); | |
137 | packet_put_int(0); | |
138 | packet_send(); | |
139 | packet_write_wait(); | |
140 | } | |
141 | ||
142 | static void | |
143 | input_service_request(int type, int plen, void *ctxt) | |
144 | { | |
145 | Authctxt *authctxt = ctxt; | |
146 | u_int len; | |
147 | int accept = 0; | |
148 | char *service = packet_get_string(&len); | |
149 | packet_done(); | |
150 | ||
151 | if (authctxt == NULL) | |
152 | fatal("input_service_request: no authctxt"); | |
153 | ||
154 | if (strcmp(service, "ssh-userauth") == 0) { | |
155 | if (!authctxt->success) { | |
156 | accept = 1; | |
157 | /* now we can handle user-auth requests */ | |
158 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); | |
159 | } | |
160 | } | |
161 | /* XXX all other service requests are denied */ | |
162 | ||
163 | if (accept) { | |
164 | packet_start(SSH2_MSG_SERVICE_ACCEPT); | |
165 | packet_put_cstring(service); | |
166 | packet_send(); | |
167 | packet_write_wait(); | |
168 | } else { | |
169 | debug("bad service request %s", service); | |
170 | packet_disconnect("bad service request %s", service); | |
171 | } | |
172 | xfree(service); | |
173 | } | |
174 | ||
175 | static void | |
176 | input_userauth_request(int type, int plen, void *ctxt) | |
177 | { | |
178 | Authctxt *authctxt = ctxt; | |
179 | Authmethod *m = NULL; | |
180 | char *user, *service, *method, *style = NULL; | |
181 | int authenticated = 0; | |
182 | ||
183 | if (authctxt == NULL) | |
184 | fatal("input_userauth_request: no authctxt"); | |
185 | ||
186 | user = packet_get_string(NULL); | |
187 | service = packet_get_string(NULL); | |
188 | method = packet_get_string(NULL); | |
189 | debug("userauth-request for user %s service %s method %s", user, service, method); | |
190 | debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); | |
191 | ||
192 | if ((style = strchr(user, ':')) != NULL) | |
193 | *style++ = 0; | |
194 | ||
195 | if (authctxt->attempt++ == 0) { | |
196 | /* setup auth context */ | |
197 | struct passwd *pw = NULL; | |
198 | pw = getpwnam(user); | |
199 | if (pw && allowed_user(pw) && strcmp(service, "ssh-connection")==0) { | |
200 | authctxt->pw = pwcopy(pw); | |
201 | authctxt->valid = 1; | |
202 | debug2("input_userauth_request: setting up authctxt for %s", user); | |
203 | #ifdef USE_PAM | |
204 | start_pam(pw->pw_name); | |
205 | #endif | |
206 | } else { | |
207 | log("input_userauth_request: illegal user %s", user); | |
208 | #ifdef USE_PAM | |
209 | start_pam("NOUSER"); | |
210 | #endif | |
211 | } | |
212 | setproctitle("%s", pw ? user : "unknown"); | |
213 | authctxt->user = xstrdup(user); | |
214 | authctxt->service = xstrdup(service); | |
215 | authctxt->style = style ? xstrdup(style) : NULL; | |
216 | } else if (strcmp(user, authctxt->user) != 0 || | |
217 | strcmp(service, authctxt->service) != 0) { | |
218 | packet_disconnect("Change of username or service not allowed: " | |
219 | "(%s,%s) -> (%s,%s)", | |
220 | authctxt->user, authctxt->service, user, service); | |
221 | } | |
222 | /* reset state */ | |
223 | dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, &protocol_error); | |
224 | authctxt->postponed = 0; | |
225 | #ifdef BSD_AUTH | |
226 | if (authctxt->as) { | |
227 | auth_close(authctxt->as); | |
228 | authctxt->as = NULL; | |
229 | } | |
230 | #endif | |
231 | ||
232 | /* try to authenticate user */ | |
233 | m = authmethod_lookup(method); | |
234 | if (m != NULL) { | |
235 | debug2("input_userauth_request: try method %s", method); | |
236 | authenticated = m->userauth(authctxt); | |
237 | } | |
238 | userauth_finish(authctxt, authenticated, method); | |
239 | ||
240 | xfree(service); | |
241 | xfree(user); | |
242 | xfree(method); | |
243 | } | |
244 | ||
245 | void | |
246 | userauth_finish(Authctxt *authctxt, int authenticated, char *method) | |
247 | { | |
248 | char *methods; | |
249 | ||
250 | if (!authctxt->valid && authenticated) | |
251 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
252 | authctxt->user); | |
253 | ||
254 | /* Special handling for root */ | |
255 | if (authenticated && authctxt->pw->pw_uid == 0 && | |
256 | !auth_root_allowed(method)) | |
257 | authenticated = 0; | |
258 | ||
259 | #ifdef USE_PAM | |
260 | if (authenticated && authctxt->user && !do_pam_account(authctxt->user, | |
261 | NULL)) | |
262 | authenticated = 0; | |
263 | #endif /* USE_PAM */ | |
264 | ||
265 | /* Log before sending the reply */ | |
266 | auth_log(authctxt, authenticated, method, " ssh2"); | |
267 | ||
268 | if (authctxt->postponed) | |
269 | return; | |
270 | ||
271 | /* XXX todo: check if multiple auth methods are needed */ | |
272 | if (authenticated == 1) { | |
273 | /* turn off userauth */ | |
274 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &protocol_error); | |
275 | packet_start(SSH2_MSG_USERAUTH_SUCCESS); | |
276 | packet_send(); | |
277 | packet_write_wait(); | |
278 | /* now we can break out */ | |
279 | authctxt->success = 1; | |
280 | } else { | |
281 | if (authctxt->failures++ > AUTH_FAIL_MAX) { | |
282 | #ifdef WITH_AIXAUTHENTICATE | |
283 | loginfailed(authctxt->user, | |
284 | get_canonical_hostname(options.reverse_mapping_check), | |
285 | "ssh"); | |
286 | #endif /* WITH_AIXAUTHENTICATE */ | |
287 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); | |
288 | } | |
289 | methods = authmethods_get(); | |
290 | packet_start(SSH2_MSG_USERAUTH_FAILURE); | |
291 | packet_put_cstring(methods); | |
292 | packet_put_char(0); /* XXX partial success, unused */ | |
293 | packet_send(); | |
294 | packet_write_wait(); | |
295 | xfree(methods); | |
296 | } | |
297 | } | |
298 | ||
299 | static void | |
300 | userauth_banner(void) | |
301 | { | |
302 | struct stat st; | |
303 | char *banner = NULL; | |
304 | off_t len, n; | |
305 | int fd; | |
306 | ||
307 | if (options.banner == NULL || (datafellows & SSH_BUG_BANNER)) | |
308 | return; | |
309 | if ((fd = open(options.banner, O_RDONLY)) < 0) | |
310 | return; | |
311 | if (fstat(fd, &st) < 0) | |
312 | goto done; | |
313 | len = st.st_size; | |
314 | banner = xmalloc(len + 1); | |
315 | if ((n = read(fd, banner, len)) < 0) | |
316 | goto done; | |
317 | banner[n] = '\0'; | |
318 | packet_start(SSH2_MSG_USERAUTH_BANNER); | |
319 | packet_put_cstring(banner); | |
320 | packet_put_cstring(""); /* language, unused */ | |
321 | packet_send(); | |
322 | debug("userauth_banner: sent"); | |
323 | done: | |
324 | if (banner) | |
325 | xfree(banner); | |
326 | close(fd); | |
327 | return; | |
328 | } | |
329 | ||
330 | static int | |
331 | userauth_none(Authctxt *authctxt) | |
332 | { | |
333 | /* disable method "none", only allowed one time */ | |
334 | Authmethod *m = authmethod_lookup("none"); | |
335 | if (m != NULL) | |
336 | m->enabled = NULL; | |
337 | packet_done(); | |
338 | userauth_banner(); | |
339 | ||
340 | if (authctxt->valid == 0) | |
341 | return(0); | |
342 | ||
343 | #ifdef HAVE_CYGWIN | |
344 | if (check_nt_auth(1, authctxt->pw->pw_uid) == 0) | |
345 | return(0); | |
346 | #endif | |
347 | #ifdef USE_PAM | |
348 | return auth_pam_password(authctxt->pw, ""); | |
349 | #elif defined(HAVE_OSF_SIA) | |
350 | return 0; | |
351 | #else /* !HAVE_OSF_SIA && !USE_PAM */ | |
352 | return auth_password(authctxt, ""); | |
353 | #endif /* USE_PAM */ | |
354 | } | |
355 | ||
356 | static int | |
357 | userauth_passwd(Authctxt *authctxt) | |
358 | { | |
359 | char *password; | |
360 | int authenticated = 0; | |
361 | int change; | |
362 | u_int len; | |
363 | change = packet_get_char(); | |
364 | if (change) | |
365 | log("password change not supported"); | |
366 | password = packet_get_string(&len); | |
367 | packet_done(); | |
368 | if (authctxt->valid && | |
369 | #ifdef HAVE_CYGWIN | |
370 | check_nt_auth(1, authctxt->pw->pw_uid) && | |
371 | #endif | |
372 | #ifdef USE_PAM | |
373 | auth_pam_password(authctxt->pw, password) == 1) | |
374 | #elif defined(HAVE_OSF_SIA) | |
375 | auth_sia_password(authctxt->user, password) == 1) | |
376 | #else /* !USE_PAM && !HAVE_OSF_SIA */ | |
377 | auth_password(authctxt, password) == 1) | |
378 | #endif /* USE_PAM */ | |
379 | authenticated = 1; | |
380 | memset(password, 0, len); | |
381 | xfree(password); | |
382 | return authenticated; | |
383 | } | |
384 | ||
385 | static int | |
386 | userauth_kbdint(Authctxt *authctxt) | |
387 | { | |
388 | int authenticated = 0; | |
389 | char *lang, *devs; | |
390 | ||
391 | lang = packet_get_string(NULL); | |
392 | devs = packet_get_string(NULL); | |
393 | packet_done(); | |
394 | ||
395 | debug("keyboard-interactive devs %s", devs); | |
396 | ||
397 | if (options.challenge_response_authentication) | |
398 | authenticated = auth2_challenge(authctxt, devs); | |
399 | ||
400 | #ifdef USE_PAM | |
401 | if (authenticated == 0 && options.pam_authentication_via_kbd_int) | |
402 | authenticated = auth2_pam(authctxt); | |
403 | #endif | |
404 | xfree(devs); | |
405 | xfree(lang); | |
406 | #ifdef HAVE_CYGWIN | |
407 | if (check_nt_auth(0, authctxt->pw->pw_uid) == 0) | |
408 | return(0); | |
409 | #endif | |
410 | return authenticated; | |
411 | } | |
412 | ||
413 | static int | |
414 | userauth_pubkey(Authctxt *authctxt) | |
415 | { | |
416 | Buffer b; | |
417 | Key *key; | |
418 | char *pkalg, *pkblob, *sig; | |
419 | u_int alen, blen, slen; | |
420 | int have_sig, pktype; | |
421 | int authenticated = 0; | |
422 | ||
423 | if (!authctxt->valid) { | |
424 | debug2("userauth_pubkey: disabled because of invalid user"); | |
425 | return 0; | |
426 | } | |
427 | have_sig = packet_get_char(); | |
428 | if (datafellows & SSH_BUG_PKAUTH) { | |
429 | debug2("userauth_pubkey: SSH_BUG_PKAUTH"); | |
430 | /* no explicit pkalg given */ | |
431 | pkblob = packet_get_string(&blen); | |
432 | buffer_init(&b); | |
433 | buffer_append(&b, pkblob, blen); | |
434 | /* so we have to extract the pkalg from the pkblob */ | |
435 | pkalg = buffer_get_string(&b, &alen); | |
436 | buffer_free(&b); | |
437 | } else { | |
438 | pkalg = packet_get_string(&alen); | |
439 | pkblob = packet_get_string(&blen); | |
440 | } | |
441 | pktype = key_type_from_name(pkalg); | |
442 | if (pktype == KEY_UNSPEC) { | |
443 | /* this is perfectly legal */ | |
444 | log("userauth_pubkey: unsupported public key algorithm: %s", pkalg); | |
445 | xfree(pkalg); | |
446 | xfree(pkblob); | |
447 | return 0; | |
448 | } | |
449 | key = key_from_blob(pkblob, blen); | |
450 | if (key != NULL) { | |
451 | if (have_sig) { | |
452 | sig = packet_get_string(&slen); | |
453 | packet_done(); | |
454 | buffer_init(&b); | |
455 | if (datafellows & SSH_OLD_SESSIONID) { | |
456 | buffer_append(&b, session_id2, session_id2_len); | |
457 | } else { | |
458 | buffer_put_string(&b, session_id2, session_id2_len); | |
459 | } | |
460 | /* reconstruct packet */ | |
461 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
462 | buffer_put_cstring(&b, authctxt->user); | |
463 | buffer_put_cstring(&b, | |
464 | datafellows & SSH_BUG_PKSERVICE ? | |
465 | "ssh-userauth" : | |
466 | authctxt->service); | |
467 | if (datafellows & SSH_BUG_PKAUTH) { | |
468 | buffer_put_char(&b, have_sig); | |
469 | } else { | |
470 | buffer_put_cstring(&b, "publickey"); | |
471 | buffer_put_char(&b, have_sig); | |
472 | buffer_put_cstring(&b, pkalg); | |
473 | } | |
474 | buffer_put_string(&b, pkblob, blen); | |
475 | #ifdef DEBUG_PK | |
476 | buffer_dump(&b); | |
477 | #endif | |
478 | /* test for correct signature */ | |
479 | if (user_key_allowed(authctxt->pw, key) && | |
480 | key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1) | |
481 | authenticated = 1; | |
482 | buffer_clear(&b); | |
483 | xfree(sig); | |
484 | } else { | |
485 | debug("test whether pkalg/pkblob are acceptable"); | |
486 | packet_done(); | |
487 | ||
488 | /* XXX fake reply and always send PK_OK ? */ | |
489 | /* | |
490 | * XXX this allows testing whether a user is allowed | |
491 | * to login: if you happen to have a valid pubkey this | |
492 | * message is sent. the message is NEVER sent at all | |
493 | * if a user is not allowed to login. is this an | |
494 | * issue? -markus | |
495 | */ | |
496 | if (user_key_allowed(authctxt->pw, key)) { | |
497 | packet_start(SSH2_MSG_USERAUTH_PK_OK); | |
498 | packet_put_string(pkalg, alen); | |
499 | packet_put_string(pkblob, blen); | |
500 | packet_send(); | |
501 | packet_write_wait(); | |
502 | authctxt->postponed = 1; | |
503 | } | |
504 | } | |
505 | if (authenticated != 1) | |
506 | auth_clear_options(); | |
507 | key_free(key); | |
508 | } | |
509 | debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg); | |
510 | xfree(pkalg); | |
511 | xfree(pkblob); | |
512 | #ifdef HAVE_CYGWIN | |
513 | if (check_nt_auth(0, authctxt->pw->pw_uid) == 0) | |
514 | return(0); | |
515 | #endif | |
516 | return authenticated; | |
517 | } | |
518 | ||
519 | static int | |
520 | userauth_hostbased(Authctxt *authctxt) | |
521 | { | |
522 | Buffer b; | |
523 | Key *key; | |
524 | char *pkalg, *pkblob, *sig, *cuser, *chost, *service; | |
525 | u_int alen, blen, slen; | |
526 | int pktype; | |
527 | int authenticated = 0; | |
528 | ||
529 | if (!authctxt->valid) { | |
530 | debug2("userauth_hostbased: disabled because of invalid user"); | |
531 | return 0; | |
532 | } | |
533 | pkalg = packet_get_string(&alen); | |
534 | pkblob = packet_get_string(&blen); | |
535 | chost = packet_get_string(NULL); | |
536 | cuser = packet_get_string(NULL); | |
537 | sig = packet_get_string(&slen); | |
538 | ||
539 | debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d", | |
540 | cuser, chost, pkalg, slen); | |
541 | #ifdef DEBUG_PK | |
542 | debug("signature:"); | |
543 | buffer_init(&b); | |
544 | buffer_append(&b, sig, slen); | |
545 | buffer_dump(&b); | |
546 | buffer_free(&b); | |
547 | #endif | |
548 | pktype = key_type_from_name(pkalg); | |
549 | if (pktype == KEY_UNSPEC) { | |
550 | /* this is perfectly legal */ | |
551 | log("userauth_hostbased: unsupported " | |
552 | "public key algorithm: %s", pkalg); | |
553 | goto done; | |
554 | } | |
555 | key = key_from_blob(pkblob, blen); | |
556 | if (key == NULL) { | |
557 | debug("userauth_hostbased: cannot decode key: %s", pkalg); | |
558 | goto done; | |
559 | } | |
560 | service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : | |
561 | authctxt->service; | |
562 | buffer_init(&b); | |
563 | buffer_put_string(&b, session_id2, session_id2_len); | |
564 | /* reconstruct packet */ | |
565 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
566 | buffer_put_cstring(&b, authctxt->user); | |
567 | buffer_put_cstring(&b, service); | |
568 | buffer_put_cstring(&b, "hostbased"); | |
569 | buffer_put_string(&b, pkalg, alen); | |
570 | buffer_put_string(&b, pkblob, blen); | |
571 | buffer_put_cstring(&b, chost); | |
572 | buffer_put_cstring(&b, cuser); | |
573 | #ifdef DEBUG_PK | |
574 | buffer_dump(&b); | |
575 | #endif | |
576 | /* test for allowed key and correct signature */ | |
577 | if (hostbased_key_allowed(authctxt->pw, cuser, chost, key) && | |
578 | key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1) | |
579 | authenticated = 1; | |
580 | ||
581 | buffer_clear(&b); | |
582 | key_free(key); | |
583 | ||
584 | done: | |
585 | debug2("userauth_hostbased: authenticated %d", authenticated); | |
586 | xfree(pkalg); | |
587 | xfree(pkblob); | |
588 | xfree(cuser); | |
589 | xfree(chost); | |
590 | xfree(sig); | |
591 | return authenticated; | |
592 | } | |
593 | ||
594 | /* get current user */ | |
595 | ||
596 | struct passwd* | |
597 | auth_get_user(void) | |
598 | { | |
599 | return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL; | |
600 | } | |
601 | ||
602 | #define DELIM "," | |
603 | ||
604 | static char * | |
605 | authmethods_get(void) | |
606 | { | |
607 | Authmethod *method = NULL; | |
608 | u_int size = 0; | |
609 | char *list; | |
610 | ||
611 | for (method = authmethods; method->name != NULL; method++) { | |
612 | if (strcmp(method->name, "none") == 0) | |
613 | continue; | |
614 | if (method->enabled != NULL && *(method->enabled) != 0) { | |
615 | if (size != 0) | |
616 | size += strlen(DELIM); | |
617 | size += strlen(method->name); | |
618 | } | |
619 | } | |
620 | size++; /* trailing '\0' */ | |
621 | list = xmalloc(size); | |
622 | list[0] = '\0'; | |
623 | ||
624 | for (method = authmethods; method->name != NULL; method++) { | |
625 | if (strcmp(method->name, "none") == 0) | |
626 | continue; | |
627 | if (method->enabled != NULL && *(method->enabled) != 0) { | |
628 | if (list[0] != '\0') | |
629 | strlcat(list, DELIM, size); | |
630 | strlcat(list, method->name, size); | |
631 | } | |
632 | } | |
633 | return list; | |
634 | } | |
635 | ||
636 | static Authmethod * | |
637 | authmethod_lookup(const char *name) | |
638 | { | |
639 | Authmethod *method = NULL; | |
640 | if (name != NULL) | |
641 | for (method = authmethods; method->name != NULL; method++) | |
642 | if (method->enabled != NULL && | |
643 | *(method->enabled) != 0 && | |
644 | strcmp(name, method->name) == 0) | |
645 | return method; | |
646 | debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); | |
647 | return NULL; | |
648 | } | |
649 | ||
650 | /* return 1 if user allows given key */ | |
651 | static int | |
652 | user_key_allowed2(struct passwd *pw, Key *key, char *file) | |
653 | { | |
654 | char line[8192]; | |
655 | int found_key = 0; | |
656 | FILE *f; | |
657 | u_long linenum = 0; | |
658 | struct stat st; | |
659 | Key *found; | |
660 | ||
661 | if (pw == NULL) | |
662 | return 0; | |
663 | ||
664 | /* Temporarily use the user's uid. */ | |
665 | temporarily_use_uid(pw); | |
666 | ||
667 | debug("trying public key file %s", file); | |
668 | ||
669 | /* Fail quietly if file does not exist */ | |
670 | if (stat(file, &st) < 0) { | |
671 | /* Restore the privileged uid. */ | |
672 | restore_uid(); | |
673 | return 0; | |
674 | } | |
675 | /* Open the file containing the authorized keys. */ | |
676 | f = fopen(file, "r"); | |
677 | if (!f) { | |
678 | /* Restore the privileged uid. */ | |
679 | restore_uid(); | |
680 | return 0; | |
681 | } | |
682 | if (options.strict_modes && | |
683 | secure_filename(f, file, pw, line, sizeof(line)) != 0) { | |
684 | fclose(f); | |
685 | log("Authentication refused: %s", line); | |
686 | restore_uid(); | |
687 | return 0; | |
688 | } | |
689 | ||
690 | found_key = 0; | |
691 | found = key_new(key->type); | |
692 | ||
693 | while (fgets(line, sizeof(line), f)) { | |
694 | char *cp, *options = NULL; | |
695 | linenum++; | |
696 | /* Skip leading whitespace, empty and comment lines. */ | |
697 | for (cp = line; *cp == ' ' || *cp == '\t'; cp++) | |
698 | ; | |
699 | if (!*cp || *cp == '\n' || *cp == '#') | |
700 | continue; | |
701 | ||
702 | if (key_read(found, &cp) != 1) { | |
703 | /* no key? check if there are options for this key */ | |
704 | int quoted = 0; | |
705 | debug2("user_key_allowed: check options: '%s'", cp); | |
706 | options = cp; | |
707 | for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) { | |
708 | if (*cp == '\\' && cp[1] == '"') | |
709 | cp++; /* Skip both */ | |
710 | else if (*cp == '"') | |
711 | quoted = !quoted; | |
712 | } | |
713 | /* Skip remaining whitespace. */ | |
714 | for (; *cp == ' ' || *cp == '\t'; cp++) | |
715 | ; | |
716 | if (key_read(found, &cp) != 1) { | |
717 | debug2("user_key_allowed: advance: '%s'", cp); | |
718 | /* still no key? advance to next line*/ | |
719 | continue; | |
720 | } | |
721 | } | |
722 | if (key_equal(found, key) && | |
723 | auth_parse_options(pw, options, file, linenum) == 1) { | |
724 | found_key = 1; | |
725 | debug("matching key found: file %s, line %lu", | |
726 | file, linenum); | |
727 | break; | |
728 | } | |
729 | } | |
730 | restore_uid(); | |
731 | fclose(f); | |
732 | key_free(found); | |
733 | if (!found_key) | |
734 | debug2("key not found"); | |
735 | return found_key; | |
736 | } | |
737 | ||
738 | /* check whether given key is in .ssh/authorized_keys* */ | |
739 | static int | |
740 | user_key_allowed(struct passwd *pw, Key *key) | |
741 | { | |
742 | int success; | |
743 | char *file; | |
744 | ||
745 | file = authorized_keys_file(pw); | |
746 | success = user_key_allowed2(pw, key, file); | |
747 | xfree(file); | |
748 | if (success) | |
749 | return success; | |
750 | ||
751 | /* try suffix "2" for backward compat, too */ | |
752 | file = authorized_keys_file2(pw); | |
753 | success = user_key_allowed2(pw, key, file); | |
754 | xfree(file); | |
755 | return success; | |
756 | } | |
757 | ||
758 | /* return 1 if given hostkey is allowed */ | |
759 | static int | |
760 | hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost, | |
761 | Key *key) | |
762 | { | |
763 | const char *resolvedname, *ipaddr, *lookup; | |
764 | int host_status, len; | |
765 | ||
766 | resolvedname = get_canonical_hostname(options.reverse_mapping_check); | |
767 | ipaddr = get_remote_ipaddr(); | |
768 | ||
769 | debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s", | |
770 | chost, resolvedname, ipaddr); | |
771 | ||
772 | if (options.hostbased_uses_name_from_packet_only) { | |
773 | if (auth_rhosts2(pw, cuser, chost, chost) == 0) | |
774 | return 0; | |
775 | lookup = chost; | |
776 | } else { | |
777 | if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') { | |
778 | debug2("stripping trailing dot from chost %s", chost); | |
779 | chost[len - 1] = '\0'; | |
780 | } | |
781 | if (strcasecmp(resolvedname, chost) != 0) | |
782 | log("userauth_hostbased mismatch: " | |
783 | "client sends %s, but we resolve %s to %s", | |
784 | chost, ipaddr, resolvedname); | |
785 | if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0) | |
786 | return 0; | |
787 | lookup = resolvedname; | |
788 | } | |
789 | debug2("userauth_hostbased: access allowed by auth_rhosts2"); | |
790 | ||
791 | host_status = check_key_in_hostfiles(pw, key, lookup, | |
792 | _PATH_SSH_SYSTEM_HOSTFILE, | |
793 | options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE); | |
794 | ||
795 | /* backward compat if no key has been found. */ | |
796 | if (host_status == HOST_NEW) | |
797 | host_status = check_key_in_hostfiles(pw, key, lookup, | |
798 | _PATH_SSH_SYSTEM_HOSTFILE2, | |
799 | options.ignore_user_known_hosts ? NULL : | |
800 | _PATH_SSH_USER_HOSTFILE2); | |
801 | ||
802 | return (host_status == HOST_OK); | |
803 | } | |
804 |