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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" | |
e9a17296 | 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" | |
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 | ||
e9a17296 | 72 | static void input_service_request(int, u_int32_t, void *); |
73 | static void input_userauth_request(int, u_int32_t, void *); | |
3c0ef626 | 74 | |
75 | /* helper */ | |
76 | static Authmethod *authmethod_lookup(const char *); | |
77 | static char *authmethods_get(void); | |
78 | static int user_key_allowed(struct passwd *, Key *); | |
79 | static int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); | |
80 | ||
81 | /* auth */ | |
82 | static void userauth_banner(void); | |
83 | static int userauth_none(Authctxt *); | |
84 | static int userauth_passwd(Authctxt *); | |
85 | static int userauth_pubkey(Authctxt *); | |
86 | static int userauth_hostbased(Authctxt *); | |
87 | static int userauth_kbdint(Authctxt *); | |
88 | ||
89 | Authmethod authmethods[] = { | |
90 | {"none", | |
91 | userauth_none, | |
92 | &one}, | |
93 | {"publickey", | |
94 | userauth_pubkey, | |
95 | &options.pubkey_authentication}, | |
96 | {"password", | |
97 | userauth_passwd, | |
98 | &options.password_authentication}, | |
99 | {"keyboard-interactive", | |
100 | userauth_kbdint, | |
101 | &options.kbd_interactive_authentication}, | |
102 | {"hostbased", | |
103 | userauth_hostbased, | |
104 | &options.hostbased_authentication}, | |
105 | {NULL, NULL, NULL} | |
106 | }; | |
107 | ||
108 | /* | |
109 | * loop until authctxt->success == TRUE | |
110 | */ | |
111 | ||
112 | void | |
e9a17296 | 113 | do_authentication2(void) |
3c0ef626 | 114 | { |
115 | Authctxt *authctxt = authctxt_new(); | |
116 | ||
117 | x_authctxt = authctxt; /*XXX*/ | |
118 | ||
119 | /* challenge-response is implemented via keyboard interactive */ | |
120 | if (options.challenge_response_authentication) | |
121 | options.kbd_interactive_authentication = 1; | |
122 | if (options.pam_authentication_via_kbd_int) | |
123 | options.kbd_interactive_authentication = 1; | |
124 | ||
e9a17296 | 125 | dispatch_init(&dispatch_protocol_error); |
3c0ef626 | 126 | dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); |
127 | dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); | |
128 | do_authenticated(authctxt); | |
129 | } | |
130 | ||
131 | static void | |
e9a17296 | 132 | input_service_request(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 133 | { |
134 | Authctxt *authctxt = ctxt; | |
135 | u_int len; | |
136 | int accept = 0; | |
137 | char *service = packet_get_string(&len); | |
e9a17296 | 138 | packet_check_eom(); |
3c0ef626 | 139 | |
140 | if (authctxt == NULL) | |
141 | fatal("input_service_request: no authctxt"); | |
142 | ||
143 | if (strcmp(service, "ssh-userauth") == 0) { | |
144 | if (!authctxt->success) { | |
145 | accept = 1; | |
146 | /* now we can handle user-auth requests */ | |
147 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); | |
148 | } | |
149 | } | |
150 | /* XXX all other service requests are denied */ | |
151 | ||
152 | if (accept) { | |
153 | packet_start(SSH2_MSG_SERVICE_ACCEPT); | |
154 | packet_put_cstring(service); | |
155 | packet_send(); | |
156 | packet_write_wait(); | |
157 | } else { | |
158 | debug("bad service request %s", service); | |
159 | packet_disconnect("bad service request %s", service); | |
160 | } | |
161 | xfree(service); | |
162 | } | |
163 | ||
164 | static void | |
e9a17296 | 165 | input_userauth_request(int type, u_int32_t seq, void *ctxt) |
3c0ef626 | 166 | { |
167 | Authctxt *authctxt = ctxt; | |
168 | Authmethod *m = NULL; | |
169 | char *user, *service, *method, *style = NULL; | |
170 | int authenticated = 0; | |
171 | ||
172 | if (authctxt == NULL) | |
173 | fatal("input_userauth_request: no authctxt"); | |
174 | ||
175 | user = packet_get_string(NULL); | |
176 | service = packet_get_string(NULL); | |
177 | method = packet_get_string(NULL); | |
178 | debug("userauth-request for user %s service %s method %s", user, service, method); | |
179 | debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); | |
180 | ||
181 | if ((style = strchr(user, ':')) != NULL) | |
182 | *style++ = 0; | |
183 | ||
184 | if (authctxt->attempt++ == 0) { | |
185 | /* setup auth context */ | |
186 | struct passwd *pw = NULL; | |
187 | pw = getpwnam(user); | |
188 | if (pw && allowed_user(pw) && strcmp(service, "ssh-connection")==0) { | |
189 | authctxt->pw = pwcopy(pw); | |
190 | authctxt->valid = 1; | |
191 | debug2("input_userauth_request: setting up authctxt for %s", user); | |
192 | #ifdef USE_PAM | |
193 | start_pam(pw->pw_name); | |
194 | #endif | |
195 | } else { | |
196 | log("input_userauth_request: illegal user %s", user); | |
197 | #ifdef USE_PAM | |
198 | start_pam("NOUSER"); | |
199 | #endif | |
200 | } | |
201 | setproctitle("%s", pw ? user : "unknown"); | |
202 | authctxt->user = xstrdup(user); | |
203 | authctxt->service = xstrdup(service); | |
204 | authctxt->style = style ? xstrdup(style) : NULL; | |
205 | } else if (strcmp(user, authctxt->user) != 0 || | |
206 | strcmp(service, authctxt->service) != 0) { | |
207 | packet_disconnect("Change of username or service not allowed: " | |
208 | "(%s,%s) -> (%s,%s)", | |
209 | authctxt->user, authctxt->service, user, service); | |
210 | } | |
211 | /* reset state */ | |
e9a17296 | 212 | auth2_challenge_stop(authctxt); |
3c0ef626 | 213 | authctxt->postponed = 0; |
3c0ef626 | 214 | |
215 | /* try to authenticate user */ | |
216 | m = authmethod_lookup(method); | |
217 | if (m != NULL) { | |
218 | debug2("input_userauth_request: try method %s", method); | |
219 | authenticated = m->userauth(authctxt); | |
220 | } | |
221 | userauth_finish(authctxt, authenticated, method); | |
222 | ||
223 | xfree(service); | |
224 | xfree(user); | |
225 | xfree(method); | |
226 | } | |
227 | ||
228 | void | |
229 | userauth_finish(Authctxt *authctxt, int authenticated, char *method) | |
230 | { | |
231 | char *methods; | |
232 | ||
233 | if (!authctxt->valid && authenticated) | |
234 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
235 | authctxt->user); | |
236 | ||
237 | /* Special handling for root */ | |
238 | if (authenticated && authctxt->pw->pw_uid == 0 && | |
239 | !auth_root_allowed(method)) | |
240 | authenticated = 0; | |
241 | ||
242 | #ifdef USE_PAM | |
243 | if (authenticated && authctxt->user && !do_pam_account(authctxt->user, | |
244 | NULL)) | |
245 | authenticated = 0; | |
246 | #endif /* USE_PAM */ | |
247 | ||
248 | /* Log before sending the reply */ | |
249 | auth_log(authctxt, authenticated, method, " ssh2"); | |
250 | ||
251 | if (authctxt->postponed) | |
252 | return; | |
253 | ||
254 | /* XXX todo: check if multiple auth methods are needed */ | |
255 | if (authenticated == 1) { | |
256 | /* turn off userauth */ | |
e9a17296 | 257 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); |
3c0ef626 | 258 | packet_start(SSH2_MSG_USERAUTH_SUCCESS); |
259 | packet_send(); | |
260 | packet_write_wait(); | |
261 | /* now we can break out */ | |
262 | authctxt->success = 1; | |
263 | } else { | |
264 | if (authctxt->failures++ > AUTH_FAIL_MAX) { | |
265 | #ifdef WITH_AIXAUTHENTICATE | |
266 | loginfailed(authctxt->user, | |
e9a17296 | 267 | get_canonical_hostname(options.verify_reverse_mapping), |
3c0ef626 | 268 | "ssh"); |
269 | #endif /* WITH_AIXAUTHENTICATE */ | |
270 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); | |
271 | } | |
272 | methods = authmethods_get(); | |
273 | packet_start(SSH2_MSG_USERAUTH_FAILURE); | |
274 | packet_put_cstring(methods); | |
275 | packet_put_char(0); /* XXX partial success, unused */ | |
276 | packet_send(); | |
277 | packet_write_wait(); | |
278 | xfree(methods); | |
279 | } | |
280 | } | |
281 | ||
282 | static void | |
283 | userauth_banner(void) | |
284 | { | |
285 | struct stat st; | |
286 | char *banner = NULL; | |
287 | off_t len, n; | |
288 | int fd; | |
289 | ||
290 | if (options.banner == NULL || (datafellows & SSH_BUG_BANNER)) | |
291 | return; | |
292 | if ((fd = open(options.banner, O_RDONLY)) < 0) | |
293 | return; | |
294 | if (fstat(fd, &st) < 0) | |
295 | goto done; | |
296 | len = st.st_size; | |
297 | banner = xmalloc(len + 1); | |
298 | if ((n = read(fd, banner, len)) < 0) | |
299 | goto done; | |
300 | banner[n] = '\0'; | |
301 | packet_start(SSH2_MSG_USERAUTH_BANNER); | |
302 | packet_put_cstring(banner); | |
303 | packet_put_cstring(""); /* language, unused */ | |
304 | packet_send(); | |
305 | debug("userauth_banner: sent"); | |
306 | done: | |
307 | if (banner) | |
308 | xfree(banner); | |
309 | close(fd); | |
310 | return; | |
311 | } | |
312 | ||
313 | static int | |
314 | userauth_none(Authctxt *authctxt) | |
315 | { | |
316 | /* disable method "none", only allowed one time */ | |
317 | Authmethod *m = authmethod_lookup("none"); | |
318 | if (m != NULL) | |
319 | m->enabled = NULL; | |
e9a17296 | 320 | packet_check_eom(); |
3c0ef626 | 321 | userauth_banner(); |
322 | ||
323 | if (authctxt->valid == 0) | |
324 | return(0); | |
325 | ||
326 | #ifdef HAVE_CYGWIN | |
e9a17296 | 327 | if (check_nt_auth(1, authctxt->pw) == 0) |
3c0ef626 | 328 | return(0); |
329 | #endif | |
330 | #ifdef USE_PAM | |
331 | return auth_pam_password(authctxt->pw, ""); | |
332 | #elif defined(HAVE_OSF_SIA) | |
333 | return 0; | |
334 | #else /* !HAVE_OSF_SIA && !USE_PAM */ | |
335 | return auth_password(authctxt, ""); | |
336 | #endif /* USE_PAM */ | |
337 | } | |
338 | ||
339 | static int | |
340 | userauth_passwd(Authctxt *authctxt) | |
341 | { | |
342 | char *password; | |
343 | int authenticated = 0; | |
344 | int change; | |
345 | u_int len; | |
346 | change = packet_get_char(); | |
347 | if (change) | |
348 | log("password change not supported"); | |
349 | password = packet_get_string(&len); | |
e9a17296 | 350 | packet_check_eom(); |
3c0ef626 | 351 | if (authctxt->valid && |
352 | #ifdef HAVE_CYGWIN | |
e9a17296 | 353 | check_nt_auth(1, authctxt->pw) && |
3c0ef626 | 354 | #endif |
355 | #ifdef USE_PAM | |
356 | auth_pam_password(authctxt->pw, password) == 1) | |
357 | #elif defined(HAVE_OSF_SIA) | |
358 | auth_sia_password(authctxt->user, password) == 1) | |
359 | #else /* !USE_PAM && !HAVE_OSF_SIA */ | |
360 | auth_password(authctxt, password) == 1) | |
361 | #endif /* USE_PAM */ | |
362 | authenticated = 1; | |
363 | memset(password, 0, len); | |
364 | xfree(password); | |
365 | return authenticated; | |
366 | } | |
367 | ||
368 | static int | |
369 | userauth_kbdint(Authctxt *authctxt) | |
370 | { | |
371 | int authenticated = 0; | |
372 | char *lang, *devs; | |
373 | ||
374 | lang = packet_get_string(NULL); | |
375 | devs = packet_get_string(NULL); | |
e9a17296 | 376 | packet_check_eom(); |
3c0ef626 | 377 | |
378 | debug("keyboard-interactive devs %s", devs); | |
379 | ||
380 | if (options.challenge_response_authentication) | |
381 | authenticated = auth2_challenge(authctxt, devs); | |
382 | ||
383 | #ifdef USE_PAM | |
384 | if (authenticated == 0 && options.pam_authentication_via_kbd_int) | |
385 | authenticated = auth2_pam(authctxt); | |
386 | #endif | |
387 | xfree(devs); | |
388 | xfree(lang); | |
389 | #ifdef HAVE_CYGWIN | |
e9a17296 | 390 | if (check_nt_auth(0, authctxt->pw) == 0) |
3c0ef626 | 391 | return(0); |
392 | #endif | |
393 | return authenticated; | |
394 | } | |
395 | ||
396 | static int | |
397 | userauth_pubkey(Authctxt *authctxt) | |
398 | { | |
399 | Buffer b; | |
e9a17296 | 400 | Key *key = NULL; |
401 | char *pkalg; | |
402 | u_char *pkblob, *sig; | |
3c0ef626 | 403 | u_int alen, blen, slen; |
404 | int have_sig, pktype; | |
405 | int authenticated = 0; | |
406 | ||
407 | if (!authctxt->valid) { | |
408 | debug2("userauth_pubkey: disabled because of invalid user"); | |
409 | return 0; | |
410 | } | |
411 | have_sig = packet_get_char(); | |
412 | if (datafellows & SSH_BUG_PKAUTH) { | |
413 | debug2("userauth_pubkey: SSH_BUG_PKAUTH"); | |
414 | /* no explicit pkalg given */ | |
415 | pkblob = packet_get_string(&blen); | |
416 | buffer_init(&b); | |
417 | buffer_append(&b, pkblob, blen); | |
418 | /* so we have to extract the pkalg from the pkblob */ | |
419 | pkalg = buffer_get_string(&b, &alen); | |
420 | buffer_free(&b); | |
421 | } else { | |
422 | pkalg = packet_get_string(&alen); | |
423 | pkblob = packet_get_string(&blen); | |
424 | } | |
425 | pktype = key_type_from_name(pkalg); | |
426 | if (pktype == KEY_UNSPEC) { | |
427 | /* this is perfectly legal */ | |
e9a17296 | 428 | log("userauth_pubkey: unsupported public key algorithm: %s", |
429 | pkalg); | |
430 | goto done; | |
3c0ef626 | 431 | } |
432 | key = key_from_blob(pkblob, blen); | |
e9a17296 | 433 | if (key == NULL) { |
434 | error("userauth_pubkey: cannot decode key: %s", pkalg); | |
435 | goto done; | |
436 | } | |
437 | if (key->type != pktype) { | |
438 | error("userauth_pubkey: type mismatch for decoded key " | |
439 | "(received %d, expected %d)", key->type, pktype); | |
440 | goto done; | |
441 | } | |
442 | if (have_sig) { | |
443 | sig = packet_get_string(&slen); | |
444 | packet_check_eom(); | |
445 | buffer_init(&b); | |
446 | if (datafellows & SSH_OLD_SESSIONID) { | |
447 | buffer_append(&b, session_id2, session_id2_len); | |
448 | } else { | |
449 | buffer_put_string(&b, session_id2, session_id2_len); | |
450 | } | |
451 | /* reconstruct packet */ | |
452 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
453 | buffer_put_cstring(&b, authctxt->user); | |
454 | buffer_put_cstring(&b, | |
455 | datafellows & SSH_BUG_PKSERVICE ? | |
456 | "ssh-userauth" : | |
457 | authctxt->service); | |
458 | if (datafellows & SSH_BUG_PKAUTH) { | |
459 | buffer_put_char(&b, have_sig); | |
460 | } else { | |
461 | buffer_put_cstring(&b, "publickey"); | |
462 | buffer_put_char(&b, have_sig); | |
463 | buffer_put_cstring(&b, pkalg); | |
464 | } | |
465 | buffer_put_string(&b, pkblob, blen); | |
3c0ef626 | 466 | #ifdef DEBUG_PK |
e9a17296 | 467 | buffer_dump(&b); |
3c0ef626 | 468 | #endif |
e9a17296 | 469 | /* test for correct signature */ |
470 | if (user_key_allowed(authctxt->pw, key) && | |
471 | key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1) | |
472 | authenticated = 1; | |
473 | buffer_clear(&b); | |
474 | xfree(sig); | |
475 | } else { | |
476 | debug("test whether pkalg/pkblob are acceptable"); | |
477 | packet_check_eom(); | |
478 | ||
479 | /* XXX fake reply and always send PK_OK ? */ | |
480 | /* | |
481 | * XXX this allows testing whether a user is allowed | |
482 | * to login: if you happen to have a valid pubkey this | |
483 | * message is sent. the message is NEVER sent at all | |
484 | * if a user is not allowed to login. is this an | |
485 | * issue? -markus | |
486 | */ | |
487 | if (user_key_allowed(authctxt->pw, key)) { | |
488 | packet_start(SSH2_MSG_USERAUTH_PK_OK); | |
489 | packet_put_string(pkalg, alen); | |
490 | packet_put_string(pkblob, blen); | |
491 | packet_send(); | |
492 | packet_write_wait(); | |
493 | authctxt->postponed = 1; | |
3c0ef626 | 494 | } |
3c0ef626 | 495 | } |
e9a17296 | 496 | if (authenticated != 1) |
497 | auth_clear_options(); | |
498 | done: | |
3c0ef626 | 499 | debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg); |
e9a17296 | 500 | if (key != NULL) |
501 | key_free(key); | |
3c0ef626 | 502 | xfree(pkalg); |
503 | xfree(pkblob); | |
504 | #ifdef HAVE_CYGWIN | |
e9a17296 | 505 | if (check_nt_auth(0, authctxt->pw) == 0) |
3c0ef626 | 506 | return(0); |
507 | #endif | |
508 | return authenticated; | |
509 | } | |
510 | ||
511 | static int | |
512 | userauth_hostbased(Authctxt *authctxt) | |
513 | { | |
514 | Buffer b; | |
e9a17296 | 515 | Key *key = NULL; |
516 | char *pkalg, *cuser, *chost, *service; | |
517 | u_char *pkblob, *sig; | |
3c0ef626 | 518 | u_int alen, blen, slen; |
519 | int pktype; | |
520 | int authenticated = 0; | |
521 | ||
522 | if (!authctxt->valid) { | |
523 | debug2("userauth_hostbased: disabled because of invalid user"); | |
524 | return 0; | |
525 | } | |
526 | pkalg = packet_get_string(&alen); | |
527 | pkblob = packet_get_string(&blen); | |
528 | chost = packet_get_string(NULL); | |
529 | cuser = packet_get_string(NULL); | |
530 | sig = packet_get_string(&slen); | |
531 | ||
532 | debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d", | |
533 | cuser, chost, pkalg, slen); | |
534 | #ifdef DEBUG_PK | |
535 | debug("signature:"); | |
536 | buffer_init(&b); | |
537 | buffer_append(&b, sig, slen); | |
538 | buffer_dump(&b); | |
539 | buffer_free(&b); | |
540 | #endif | |
541 | pktype = key_type_from_name(pkalg); | |
542 | if (pktype == KEY_UNSPEC) { | |
543 | /* this is perfectly legal */ | |
544 | log("userauth_hostbased: unsupported " | |
545 | "public key algorithm: %s", pkalg); | |
546 | goto done; | |
547 | } | |
548 | key = key_from_blob(pkblob, blen); | |
549 | if (key == NULL) { | |
e9a17296 | 550 | error("userauth_hostbased: cannot decode key: %s", pkalg); |
551 | goto done; | |
552 | } | |
553 | if (key->type != pktype) { | |
554 | error("userauth_hostbased: type mismatch for decoded key " | |
555 | "(received %d, expected %d)", key->type, pktype); | |
3c0ef626 | 556 | goto done; |
557 | } | |
558 | service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : | |
559 | authctxt->service; | |
560 | buffer_init(&b); | |
561 | buffer_put_string(&b, session_id2, session_id2_len); | |
562 | /* reconstruct packet */ | |
563 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
564 | buffer_put_cstring(&b, authctxt->user); | |
565 | buffer_put_cstring(&b, service); | |
566 | buffer_put_cstring(&b, "hostbased"); | |
567 | buffer_put_string(&b, pkalg, alen); | |
568 | buffer_put_string(&b, pkblob, blen); | |
569 | buffer_put_cstring(&b, chost); | |
570 | buffer_put_cstring(&b, cuser); | |
571 | #ifdef DEBUG_PK | |
572 | buffer_dump(&b); | |
573 | #endif | |
574 | /* test for allowed key and correct signature */ | |
575 | if (hostbased_key_allowed(authctxt->pw, cuser, chost, key) && | |
576 | key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1) | |
577 | authenticated = 1; | |
578 | ||
579 | buffer_clear(&b); | |
3c0ef626 | 580 | done: |
581 | debug2("userauth_hostbased: authenticated %d", authenticated); | |
e9a17296 | 582 | if (key != NULL) |
583 | key_free(key); | |
3c0ef626 | 584 | xfree(pkalg); |
585 | xfree(pkblob); | |
586 | xfree(cuser); | |
587 | xfree(chost); | |
588 | xfree(sig); | |
589 | return authenticated; | |
590 | } | |
591 | ||
592 | /* get current user */ | |
593 | ||
594 | struct passwd* | |
595 | auth_get_user(void) | |
596 | { | |
597 | return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL; | |
598 | } | |
599 | ||
600 | #define DELIM "," | |
601 | ||
602 | static char * | |
603 | authmethods_get(void) | |
604 | { | |
605 | Authmethod *method = NULL; | |
e9a17296 | 606 | Buffer b; |
3c0ef626 | 607 | char *list; |
608 | ||
e9a17296 | 609 | buffer_init(&b); |
3c0ef626 | 610 | for (method = authmethods; method->name != NULL; method++) { |
611 | if (strcmp(method->name, "none") == 0) | |
612 | continue; | |
613 | if (method->enabled != NULL && *(method->enabled) != 0) { | |
e9a17296 | 614 | if (buffer_len(&b) > 0) |
615 | buffer_append(&b, ",", 1); | |
616 | buffer_append(&b, method->name, strlen(method->name)); | |
3c0ef626 | 617 | } |
618 | } | |
e9a17296 | 619 | buffer_append(&b, "\0", 1); |
620 | list = xstrdup(buffer_ptr(&b)); | |
621 | buffer_free(&b); | |
3c0ef626 | 622 | return list; |
623 | } | |
624 | ||
625 | static Authmethod * | |
626 | authmethod_lookup(const char *name) | |
627 | { | |
628 | Authmethod *method = NULL; | |
629 | if (name != NULL) | |
630 | for (method = authmethods; method->name != NULL; method++) | |
631 | if (method->enabled != NULL && | |
632 | *(method->enabled) != 0 && | |
633 | strcmp(name, method->name) == 0) | |
634 | return method; | |
635 | debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); | |
636 | return NULL; | |
637 | } | |
638 | ||
639 | /* return 1 if user allows given key */ | |
640 | static int | |
641 | user_key_allowed2(struct passwd *pw, Key *key, char *file) | |
642 | { | |
643 | char line[8192]; | |
644 | int found_key = 0; | |
645 | FILE *f; | |
646 | u_long linenum = 0; | |
647 | struct stat st; | |
648 | Key *found; | |
e9a17296 | 649 | char *fp; |
3c0ef626 | 650 | |
651 | if (pw == NULL) | |
652 | return 0; | |
653 | ||
654 | /* Temporarily use the user's uid. */ | |
655 | temporarily_use_uid(pw); | |
656 | ||
657 | debug("trying public key file %s", file); | |
658 | ||
659 | /* Fail quietly if file does not exist */ | |
660 | if (stat(file, &st) < 0) { | |
661 | /* Restore the privileged uid. */ | |
662 | restore_uid(); | |
663 | return 0; | |
664 | } | |
665 | /* Open the file containing the authorized keys. */ | |
666 | f = fopen(file, "r"); | |
667 | if (!f) { | |
668 | /* Restore the privileged uid. */ | |
669 | restore_uid(); | |
670 | return 0; | |
671 | } | |
672 | if (options.strict_modes && | |
673 | secure_filename(f, file, pw, line, sizeof(line)) != 0) { | |
674 | fclose(f); | |
675 | log("Authentication refused: %s", line); | |
676 | restore_uid(); | |
677 | return 0; | |
678 | } | |
679 | ||
680 | found_key = 0; | |
681 | found = key_new(key->type); | |
682 | ||
683 | while (fgets(line, sizeof(line), f)) { | |
684 | char *cp, *options = NULL; | |
685 | linenum++; | |
686 | /* Skip leading whitespace, empty and comment lines. */ | |
687 | for (cp = line; *cp == ' ' || *cp == '\t'; cp++) | |
688 | ; | |
689 | if (!*cp || *cp == '\n' || *cp == '#') | |
690 | continue; | |
691 | ||
692 | if (key_read(found, &cp) != 1) { | |
693 | /* no key? check if there are options for this key */ | |
694 | int quoted = 0; | |
695 | debug2("user_key_allowed: check options: '%s'", cp); | |
696 | options = cp; | |
697 | for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) { | |
698 | if (*cp == '\\' && cp[1] == '"') | |
699 | cp++; /* Skip both */ | |
700 | else if (*cp == '"') | |
701 | quoted = !quoted; | |
702 | } | |
703 | /* Skip remaining whitespace. */ | |
704 | for (; *cp == ' ' || *cp == '\t'; cp++) | |
705 | ; | |
706 | if (key_read(found, &cp) != 1) { | |
707 | debug2("user_key_allowed: advance: '%s'", cp); | |
708 | /* still no key? advance to next line*/ | |
709 | continue; | |
710 | } | |
711 | } | |
712 | if (key_equal(found, key) && | |
713 | auth_parse_options(pw, options, file, linenum) == 1) { | |
714 | found_key = 1; | |
715 | debug("matching key found: file %s, line %lu", | |
716 | file, linenum); | |
e9a17296 | 717 | fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX); |
718 | verbose("Found matching %s key: %s", | |
719 | key_type(found), fp); | |
720 | xfree(fp); | |
3c0ef626 | 721 | break; |
722 | } | |
723 | } | |
724 | restore_uid(); | |
725 | fclose(f); | |
726 | key_free(found); | |
727 | if (!found_key) | |
728 | debug2("key not found"); | |
729 | return found_key; | |
730 | } | |
731 | ||
732 | /* check whether given key is in .ssh/authorized_keys* */ | |
733 | static int | |
734 | user_key_allowed(struct passwd *pw, Key *key) | |
735 | { | |
736 | int success; | |
737 | char *file; | |
738 | ||
739 | file = authorized_keys_file(pw); | |
740 | success = user_key_allowed2(pw, key, file); | |
741 | xfree(file); | |
742 | if (success) | |
743 | return success; | |
744 | ||
745 | /* try suffix "2" for backward compat, too */ | |
746 | file = authorized_keys_file2(pw); | |
747 | success = user_key_allowed2(pw, key, file); | |
748 | xfree(file); | |
749 | return success; | |
750 | } | |
751 | ||
752 | /* return 1 if given hostkey is allowed */ | |
753 | static int | |
754 | hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost, | |
755 | Key *key) | |
756 | { | |
757 | const char *resolvedname, *ipaddr, *lookup; | |
e9a17296 | 758 | HostStatus host_status; |
759 | int len; | |
3c0ef626 | 760 | |
e9a17296 | 761 | resolvedname = get_canonical_hostname(options.verify_reverse_mapping); |
3c0ef626 | 762 | ipaddr = get_remote_ipaddr(); |
763 | ||
764 | debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s", | |
765 | chost, resolvedname, ipaddr); | |
766 | ||
767 | if (options.hostbased_uses_name_from_packet_only) { | |
768 | if (auth_rhosts2(pw, cuser, chost, chost) == 0) | |
769 | return 0; | |
770 | lookup = chost; | |
771 | } else { | |
772 | if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') { | |
773 | debug2("stripping trailing dot from chost %s", chost); | |
774 | chost[len - 1] = '\0'; | |
775 | } | |
776 | if (strcasecmp(resolvedname, chost) != 0) | |
777 | log("userauth_hostbased mismatch: " | |
778 | "client sends %s, but we resolve %s to %s", | |
779 | chost, ipaddr, resolvedname); | |
780 | if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0) | |
781 | return 0; | |
782 | lookup = resolvedname; | |
783 | } | |
784 | debug2("userauth_hostbased: access allowed by auth_rhosts2"); | |
785 | ||
786 | host_status = check_key_in_hostfiles(pw, key, lookup, | |
787 | _PATH_SSH_SYSTEM_HOSTFILE, | |
788 | options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE); | |
789 | ||
790 | /* backward compat if no key has been found. */ | |
791 | if (host_status == HOST_NEW) | |
792 | host_status = check_key_in_hostfiles(pw, key, lookup, | |
793 | _PATH_SSH_SYSTEM_HOSTFILE2, | |
794 | options.ignore_user_known_hosts ? NULL : | |
795 | _PATH_SSH_USER_HOSTFILE2); | |
796 | ||
797 | return (host_status == HOST_OK); | |
798 | } |