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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" | |
700318f3 | 26 | RCSID("$OpenBSD: auth2.c,v 1.91 2002/05/13 02:37:39 itojun 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" | |
3c0ef626 | 50 | #include "hostfile.h" |
51 | #include "canohost.h" | |
52 | #include "match.h" | |
700318f3 | 53 | #include "monitor_wrap.h" |
54 | #include "atomicio.h" | |
3c0ef626 | 55 | |
c45e7273 | 56 | #ifdef GSSAPI |
57 | #include "ssh-gss.h" | |
58 | #endif | |
59 | ||
3c0ef626 | 60 | /* import */ |
61 | extern ServerOptions options; | |
62 | extern u_char *session_id2; | |
63 | extern int session_id2_len; | |
64 | ||
700318f3 | 65 | Authctxt *x_authctxt = NULL; |
3c0ef626 | 66 | static int one = 1; |
67 | ||
68 | typedef struct Authmethod Authmethod; | |
69 | struct Authmethod { | |
70 | char *name; | |
71 | int (*userauth)(Authctxt *authctxt); | |
72 | int *enabled; | |
73 | }; | |
74 | ||
75 | /* protocol */ | |
76 | ||
e9a17296 | 77 | static void input_service_request(int, u_int32_t, void *); |
78 | static void input_userauth_request(int, u_int32_t, void *); | |
3c0ef626 | 79 | |
80 | /* helper */ | |
81 | static Authmethod *authmethod_lookup(const char *); | |
82 | static char *authmethods_get(void); | |
700318f3 | 83 | int user_key_allowed(struct passwd *, Key *); |
84 | int hostbased_key_allowed(struct passwd *, const char *, char *, Key *); | |
3c0ef626 | 85 | |
86 | /* auth */ | |
87 | static void userauth_banner(void); | |
88 | static int userauth_none(Authctxt *); | |
89 | static int userauth_passwd(Authctxt *); | |
90 | static int userauth_pubkey(Authctxt *); | |
91 | static int userauth_hostbased(Authctxt *); | |
92 | static int userauth_kbdint(Authctxt *); | |
93 | ||
c45e7273 | 94 | #ifdef GSSAPI |
95 | int userauth_external(Authctxt *authctxt); | |
96 | int userauth_gssapi(Authctxt *authctxt); | |
97 | #endif | |
98 | ||
3c0ef626 | 99 | Authmethod authmethods[] = { |
100 | {"none", | |
101 | userauth_none, | |
102 | &one}, | |
c45e7273 | 103 | #ifdef GSSAPI |
104 | {"external-keyx", | |
105 | userauth_external, | |
106 | &options.gss_authentication}, | |
107 | {"gssapi", | |
108 | userauth_gssapi, | |
109 | &options.gss_authentication}, | |
110 | #endif | |
3c0ef626 | 111 | {"publickey", |
112 | userauth_pubkey, | |
113 | &options.pubkey_authentication}, | |
114 | {"password", | |
115 | userauth_passwd, | |
116 | &options.password_authentication}, | |
117 | {"keyboard-interactive", | |
118 | userauth_kbdint, | |
119 | &options.kbd_interactive_authentication}, | |
120 | {"hostbased", | |
121 | userauth_hostbased, | |
122 | &options.hostbased_authentication}, | |
123 | {NULL, NULL, NULL} | |
124 | }; | |
125 | ||
126 | /* | |
127 | * loop until authctxt->success == TRUE | |
128 | */ | |
129 | ||
700318f3 | 130 | Authctxt * |
e9a17296 | 131 | do_authentication2(void) |
3c0ef626 | 132 | { |
133 | Authctxt *authctxt = authctxt_new(); | |
134 | ||
135 | x_authctxt = authctxt; /*XXX*/ | |
136 | ||
137 | /* challenge-response is implemented via keyboard interactive */ | |
138 | if (options.challenge_response_authentication) | |
139 | options.kbd_interactive_authentication = 1; | |
140 | if (options.pam_authentication_via_kbd_int) | |
141 | options.kbd_interactive_authentication = 1; | |
700318f3 | 142 | if (use_privsep) |
143 | options.pam_authentication_via_kbd_int = 0; | |
3c0ef626 | 144 | |
e9a17296 | 145 | dispatch_init(&dispatch_protocol_error); |
3c0ef626 | 146 | dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request); |
147 | dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt); | |
700318f3 | 148 | |
149 | return (authctxt); | |
3c0ef626 | 150 | } |
151 | ||
152 | static void | |
e9a17296 | 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); | |
e9a17296 | 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 | |
e9a17296 | 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); | |
199 | debug("userauth-request for user %s service %s method %s", user, service, method); | |
200 | debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); | |
201 | ||
202 | if ((style = strchr(user, ':')) != NULL) | |
203 | *style++ = 0; | |
204 | ||
205 | if (authctxt->attempt++ == 0) { | |
206 | /* setup auth context */ | |
700318f3 | 207 | authctxt->pw = PRIVSEP(getpwnamallow(user)); |
208 | if (authctxt->pw && strcmp(service, "ssh-connection")==0) { | |
3c0ef626 | 209 | authctxt->valid = 1; |
210 | debug2("input_userauth_request: setting up authctxt for %s", user); | |
211 | #ifdef USE_PAM | |
700318f3 | 212 | PRIVSEP(start_pam(authctxt->pw->pw_name)); |
3c0ef626 | 213 | #endif |
214 | } else { | |
215 | log("input_userauth_request: illegal user %s", user); | |
216 | #ifdef USE_PAM | |
700318f3 | 217 | PRIVSEP(start_pam("NOUSER")); |
3c0ef626 | 218 | #endif |
219 | } | |
700318f3 | 220 | setproctitle("%s%s", authctxt->pw ? user : "unknown", |
221 | use_privsep ? " [net]" : ""); | |
3c0ef626 | 222 | authctxt->user = xstrdup(user); |
223 | authctxt->service = xstrdup(service); | |
224 | authctxt->style = style ? xstrdup(style) : NULL; | |
700318f3 | 225 | if (use_privsep) |
226 | mm_inform_authserv(service, style); | |
3c0ef626 | 227 | } else if (strcmp(user, authctxt->user) != 0 || |
228 | strcmp(service, authctxt->service) != 0) { | |
229 | packet_disconnect("Change of username or service not allowed: " | |
230 | "(%s,%s) -> (%s,%s)", | |
231 | authctxt->user, authctxt->service, user, service); | |
232 | } | |
233 | /* reset state */ | |
e9a17296 | 234 | auth2_challenge_stop(authctxt); |
c45e7273 | 235 | |
236 | #ifdef GSSAPI | |
237 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); | |
238 | dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); | |
239 | #endif | |
240 | ||
3c0ef626 | 241 | authctxt->postponed = 0; |
3c0ef626 | 242 | |
243 | /* try to authenticate user */ | |
244 | m = authmethod_lookup(method); | |
245 | if (m != NULL) { | |
246 | debug2("input_userauth_request: try method %s", method); | |
247 | authenticated = m->userauth(authctxt); | |
248 | } | |
249 | userauth_finish(authctxt, authenticated, method); | |
250 | ||
251 | xfree(service); | |
252 | xfree(user); | |
253 | xfree(method); | |
254 | } | |
255 | ||
256 | void | |
257 | userauth_finish(Authctxt *authctxt, int authenticated, char *method) | |
258 | { | |
259 | char *methods; | |
260 | ||
261 | if (!authctxt->valid && authenticated) | |
262 | fatal("INTERNAL ERROR: authenticated invalid user %s", | |
263 | authctxt->user); | |
264 | ||
265 | /* Special handling for root */ | |
266 | if (authenticated && authctxt->pw->pw_uid == 0 && | |
267 | !auth_root_allowed(method)) | |
268 | authenticated = 0; | |
269 | ||
270 | #ifdef USE_PAM | |
700318f3 | 271 | if (!use_privsep && authenticated && authctxt->user && |
272 | !do_pam_account(authctxt->user, NULL)) | |
3c0ef626 | 273 | authenticated = 0; |
274 | #endif /* USE_PAM */ | |
275 | ||
276 | /* Log before sending the reply */ | |
277 | auth_log(authctxt, authenticated, method, " ssh2"); | |
278 | ||
279 | if (authctxt->postponed) | |
280 | return; | |
281 | ||
282 | /* XXX todo: check if multiple auth methods are needed */ | |
283 | if (authenticated == 1) { | |
284 | /* turn off userauth */ | |
e9a17296 | 285 | dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); |
3c0ef626 | 286 | packet_start(SSH2_MSG_USERAUTH_SUCCESS); |
287 | packet_send(); | |
288 | packet_write_wait(); | |
289 | /* now we can break out */ | |
290 | authctxt->success = 1; | |
291 | } else { | |
292 | if (authctxt->failures++ > AUTH_FAIL_MAX) { | |
293 | #ifdef WITH_AIXAUTHENTICATE | |
294 | loginfailed(authctxt->user, | |
e9a17296 | 295 | get_canonical_hostname(options.verify_reverse_mapping), |
3c0ef626 | 296 | "ssh"); |
297 | #endif /* WITH_AIXAUTHENTICATE */ | |
298 | packet_disconnect(AUTH_FAIL_MSG, authctxt->user); | |
299 | } | |
300 | methods = authmethods_get(); | |
301 | packet_start(SSH2_MSG_USERAUTH_FAILURE); | |
302 | packet_put_cstring(methods); | |
303 | packet_put_char(0); /* XXX partial success, unused */ | |
304 | packet_send(); | |
305 | packet_write_wait(); | |
306 | xfree(methods); | |
307 | } | |
308 | } | |
309 | ||
700318f3 | 310 | char * |
311 | auth2_read_banner(void) | |
3c0ef626 | 312 | { |
313 | struct stat st; | |
314 | char *banner = NULL; | |
315 | off_t len, n; | |
316 | int fd; | |
317 | ||
700318f3 | 318 | if ((fd = open(options.banner, O_RDONLY)) == -1) |
319 | return (NULL); | |
320 | if (fstat(fd, &st) == -1) { | |
321 | close(fd); | |
322 | return (NULL); | |
323 | } | |
3c0ef626 | 324 | len = st.st_size; |
325 | banner = xmalloc(len + 1); | |
700318f3 | 326 | n = atomicio(read, fd, banner, len); |
327 | close(fd); | |
328 | ||
329 | if (n != len) { | |
330 | free(banner); | |
331 | return (NULL); | |
332 | } | |
3c0ef626 | 333 | banner[n] = '\0'; |
700318f3 | 334 | |
335 | return (banner); | |
336 | } | |
337 | ||
338 | static void | |
339 | userauth_banner(void) | |
340 | { | |
341 | char *banner = NULL; | |
342 | ||
343 | if (options.banner == NULL || (datafellows & SSH_BUG_BANNER)) | |
344 | return; | |
345 | ||
346 | if ((banner = PRIVSEP(auth2_read_banner())) == NULL) | |
347 | goto done; | |
348 | ||
3c0ef626 | 349 | packet_start(SSH2_MSG_USERAUTH_BANNER); |
350 | packet_put_cstring(banner); | |
351 | packet_put_cstring(""); /* language, unused */ | |
352 | packet_send(); | |
353 | debug("userauth_banner: sent"); | |
354 | done: | |
355 | if (banner) | |
356 | xfree(banner); | |
3c0ef626 | 357 | return; |
358 | } | |
359 | ||
360 | static int | |
361 | userauth_none(Authctxt *authctxt) | |
362 | { | |
363 | /* disable method "none", only allowed one time */ | |
364 | Authmethod *m = authmethod_lookup("none"); | |
365 | if (m != NULL) | |
366 | m->enabled = NULL; | |
e9a17296 | 367 | packet_check_eom(); |
3c0ef626 | 368 | userauth_banner(); |
369 | ||
370 | if (authctxt->valid == 0) | |
371 | return(0); | |
372 | ||
373 | #ifdef HAVE_CYGWIN | |
e9a17296 | 374 | if (check_nt_auth(1, authctxt->pw) == 0) |
3c0ef626 | 375 | return(0); |
376 | #endif | |
700318f3 | 377 | return PRIVSEP(auth_password(authctxt, "")); |
3c0ef626 | 378 | } |
379 | ||
380 | static int | |
381 | userauth_passwd(Authctxt *authctxt) | |
382 | { | |
383 | char *password; | |
384 | int authenticated = 0; | |
385 | int change; | |
386 | u_int len; | |
387 | change = packet_get_char(); | |
388 | if (change) | |
389 | log("password change not supported"); | |
390 | password = packet_get_string(&len); | |
e9a17296 | 391 | packet_check_eom(); |
3c0ef626 | 392 | if (authctxt->valid && |
393 | #ifdef HAVE_CYGWIN | |
e9a17296 | 394 | check_nt_auth(1, authctxt->pw) && |
3c0ef626 | 395 | #endif |
700318f3 | 396 | PRIVSEP(auth_password(authctxt, password)) == 1) |
3c0ef626 | 397 | authenticated = 1; |
398 | memset(password, 0, len); | |
399 | xfree(password); | |
400 | return authenticated; | |
401 | } | |
402 | ||
403 | static int | |
404 | userauth_kbdint(Authctxt *authctxt) | |
405 | { | |
406 | int authenticated = 0; | |
407 | char *lang, *devs; | |
408 | ||
409 | lang = packet_get_string(NULL); | |
410 | devs = packet_get_string(NULL); | |
e9a17296 | 411 | packet_check_eom(); |
3c0ef626 | 412 | |
413 | debug("keyboard-interactive devs %s", devs); | |
414 | ||
415 | if (options.challenge_response_authentication) | |
416 | authenticated = auth2_challenge(authctxt, devs); | |
417 | ||
418 | #ifdef USE_PAM | |
419 | if (authenticated == 0 && options.pam_authentication_via_kbd_int) | |
420 | authenticated = auth2_pam(authctxt); | |
421 | #endif | |
422 | xfree(devs); | |
423 | xfree(lang); | |
424 | #ifdef HAVE_CYGWIN | |
e9a17296 | 425 | if (check_nt_auth(0, authctxt->pw) == 0) |
3c0ef626 | 426 | return(0); |
427 | #endif | |
428 | return authenticated; | |
429 | } | |
430 | ||
431 | static int | |
432 | userauth_pubkey(Authctxt *authctxt) | |
433 | { | |
434 | Buffer b; | |
e9a17296 | 435 | Key *key = NULL; |
436 | char *pkalg; | |
437 | u_char *pkblob, *sig; | |
3c0ef626 | 438 | u_int alen, blen, slen; |
439 | int have_sig, pktype; | |
440 | int authenticated = 0; | |
441 | ||
442 | if (!authctxt->valid) { | |
443 | debug2("userauth_pubkey: disabled because of invalid user"); | |
444 | return 0; | |
445 | } | |
446 | have_sig = packet_get_char(); | |
447 | if (datafellows & SSH_BUG_PKAUTH) { | |
448 | debug2("userauth_pubkey: SSH_BUG_PKAUTH"); | |
449 | /* no explicit pkalg given */ | |
450 | pkblob = packet_get_string(&blen); | |
451 | buffer_init(&b); | |
452 | buffer_append(&b, pkblob, blen); | |
453 | /* so we have to extract the pkalg from the pkblob */ | |
454 | pkalg = buffer_get_string(&b, &alen); | |
455 | buffer_free(&b); | |
456 | } else { | |
457 | pkalg = packet_get_string(&alen); | |
458 | pkblob = packet_get_string(&blen); | |
459 | } | |
460 | pktype = key_type_from_name(pkalg); | |
461 | if (pktype == KEY_UNSPEC) { | |
462 | /* this is perfectly legal */ | |
e9a17296 | 463 | log("userauth_pubkey: unsupported public key algorithm: %s", |
464 | pkalg); | |
465 | goto done; | |
3c0ef626 | 466 | } |
467 | key = key_from_blob(pkblob, blen); | |
e9a17296 | 468 | if (key == NULL) { |
469 | error("userauth_pubkey: cannot decode key: %s", pkalg); | |
470 | goto done; | |
471 | } | |
472 | if (key->type != pktype) { | |
473 | error("userauth_pubkey: type mismatch for decoded key " | |
474 | "(received %d, expected %d)", key->type, pktype); | |
475 | goto done; | |
476 | } | |
477 | if (have_sig) { | |
478 | sig = packet_get_string(&slen); | |
479 | packet_check_eom(); | |
480 | buffer_init(&b); | |
481 | if (datafellows & SSH_OLD_SESSIONID) { | |
482 | buffer_append(&b, session_id2, session_id2_len); | |
483 | } else { | |
484 | buffer_put_string(&b, session_id2, session_id2_len); | |
485 | } | |
486 | /* reconstruct packet */ | |
487 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
488 | buffer_put_cstring(&b, authctxt->user); | |
489 | buffer_put_cstring(&b, | |
490 | datafellows & SSH_BUG_PKSERVICE ? | |
491 | "ssh-userauth" : | |
492 | authctxt->service); | |
493 | if (datafellows & SSH_BUG_PKAUTH) { | |
494 | buffer_put_char(&b, have_sig); | |
495 | } else { | |
496 | buffer_put_cstring(&b, "publickey"); | |
497 | buffer_put_char(&b, have_sig); | |
498 | buffer_put_cstring(&b, pkalg); | |
499 | } | |
500 | buffer_put_string(&b, pkblob, blen); | |
3c0ef626 | 501 | #ifdef DEBUG_PK |
e9a17296 | 502 | buffer_dump(&b); |
3c0ef626 | 503 | #endif |
e9a17296 | 504 | /* test for correct signature */ |
700318f3 | 505 | authenticated = 0; |
506 | if (PRIVSEP(user_key_allowed(authctxt->pw, key)) && | |
507 | PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b), | |
508 | buffer_len(&b))) == 1) | |
e9a17296 | 509 | authenticated = 1; |
510 | buffer_clear(&b); | |
511 | xfree(sig); | |
512 | } else { | |
513 | debug("test whether pkalg/pkblob are acceptable"); | |
514 | packet_check_eom(); | |
515 | ||
516 | /* XXX fake reply and always send PK_OK ? */ | |
517 | /* | |
518 | * XXX this allows testing whether a user is allowed | |
519 | * to login: if you happen to have a valid pubkey this | |
520 | * message is sent. the message is NEVER sent at all | |
521 | * if a user is not allowed to login. is this an | |
522 | * issue? -markus | |
523 | */ | |
700318f3 | 524 | if (PRIVSEP(user_key_allowed(authctxt->pw, key))) { |
e9a17296 | 525 | packet_start(SSH2_MSG_USERAUTH_PK_OK); |
526 | packet_put_string(pkalg, alen); | |
527 | packet_put_string(pkblob, blen); | |
528 | packet_send(); | |
529 | packet_write_wait(); | |
530 | authctxt->postponed = 1; | |
3c0ef626 | 531 | } |
3c0ef626 | 532 | } |
e9a17296 | 533 | if (authenticated != 1) |
534 | auth_clear_options(); | |
535 | done: | |
3c0ef626 | 536 | debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg); |
e9a17296 | 537 | if (key != NULL) |
538 | key_free(key); | |
3c0ef626 | 539 | xfree(pkalg); |
540 | xfree(pkblob); | |
541 | #ifdef HAVE_CYGWIN | |
e9a17296 | 542 | if (check_nt_auth(0, authctxt->pw) == 0) |
3c0ef626 | 543 | return(0); |
544 | #endif | |
545 | return authenticated; | |
546 | } | |
547 | ||
548 | static int | |
549 | userauth_hostbased(Authctxt *authctxt) | |
550 | { | |
551 | Buffer b; | |
e9a17296 | 552 | Key *key = NULL; |
553 | char *pkalg, *cuser, *chost, *service; | |
554 | u_char *pkblob, *sig; | |
3c0ef626 | 555 | u_int alen, blen, slen; |
556 | int pktype; | |
557 | int authenticated = 0; | |
558 | ||
559 | if (!authctxt->valid) { | |
560 | debug2("userauth_hostbased: disabled because of invalid user"); | |
561 | return 0; | |
562 | } | |
563 | pkalg = packet_get_string(&alen); | |
564 | pkblob = packet_get_string(&blen); | |
565 | chost = packet_get_string(NULL); | |
566 | cuser = packet_get_string(NULL); | |
567 | sig = packet_get_string(&slen); | |
568 | ||
569 | debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d", | |
570 | cuser, chost, pkalg, slen); | |
571 | #ifdef DEBUG_PK | |
572 | debug("signature:"); | |
573 | buffer_init(&b); | |
574 | buffer_append(&b, sig, slen); | |
575 | buffer_dump(&b); | |
576 | buffer_free(&b); | |
577 | #endif | |
578 | pktype = key_type_from_name(pkalg); | |
579 | if (pktype == KEY_UNSPEC) { | |
580 | /* this is perfectly legal */ | |
581 | log("userauth_hostbased: unsupported " | |
582 | "public key algorithm: %s", pkalg); | |
583 | goto done; | |
584 | } | |
585 | key = key_from_blob(pkblob, blen); | |
586 | if (key == NULL) { | |
e9a17296 | 587 | error("userauth_hostbased: cannot decode key: %s", pkalg); |
588 | goto done; | |
589 | } | |
590 | if (key->type != pktype) { | |
591 | error("userauth_hostbased: type mismatch for decoded key " | |
592 | "(received %d, expected %d)", key->type, pktype); | |
3c0ef626 | 593 | goto done; |
594 | } | |
595 | service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" : | |
596 | authctxt->service; | |
597 | buffer_init(&b); | |
598 | buffer_put_string(&b, session_id2, session_id2_len); | |
599 | /* reconstruct packet */ | |
600 | buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST); | |
601 | buffer_put_cstring(&b, authctxt->user); | |
602 | buffer_put_cstring(&b, service); | |
603 | buffer_put_cstring(&b, "hostbased"); | |
604 | buffer_put_string(&b, pkalg, alen); | |
605 | buffer_put_string(&b, pkblob, blen); | |
606 | buffer_put_cstring(&b, chost); | |
607 | buffer_put_cstring(&b, cuser); | |
608 | #ifdef DEBUG_PK | |
609 | buffer_dump(&b); | |
610 | #endif | |
611 | /* test for allowed key and correct signature */ | |
700318f3 | 612 | authenticated = 0; |
613 | if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) && | |
614 | PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b), | |
615 | buffer_len(&b))) == 1) | |
3c0ef626 | 616 | authenticated = 1; |
617 | ||
618 | buffer_clear(&b); | |
3c0ef626 | 619 | done: |
620 | debug2("userauth_hostbased: authenticated %d", authenticated); | |
e9a17296 | 621 | if (key != NULL) |
622 | key_free(key); | |
3c0ef626 | 623 | xfree(pkalg); |
624 | xfree(pkblob); | |
625 | xfree(cuser); | |
626 | xfree(chost); | |
627 | xfree(sig); | |
628 | return authenticated; | |
629 | } | |
630 | ||
631 | /* get current user */ | |
632 | ||
633 | struct passwd* | |
634 | auth_get_user(void) | |
635 | { | |
636 | return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL; | |
637 | } | |
638 | ||
639 | #define DELIM "," | |
640 | ||
641 | static char * | |
642 | authmethods_get(void) | |
643 | { | |
644 | Authmethod *method = NULL; | |
e9a17296 | 645 | Buffer b; |
3c0ef626 | 646 | char *list; |
647 | ||
e9a17296 | 648 | buffer_init(&b); |
3c0ef626 | 649 | for (method = authmethods; method->name != NULL; method++) { |
650 | if (strcmp(method->name, "none") == 0) | |
651 | continue; | |
652 | if (method->enabled != NULL && *(method->enabled) != 0) { | |
e9a17296 | 653 | if (buffer_len(&b) > 0) |
654 | buffer_append(&b, ",", 1); | |
655 | buffer_append(&b, method->name, strlen(method->name)); | |
3c0ef626 | 656 | } |
657 | } | |
e9a17296 | 658 | buffer_append(&b, "\0", 1); |
659 | list = xstrdup(buffer_ptr(&b)); | |
660 | buffer_free(&b); | |
3c0ef626 | 661 | return list; |
662 | } | |
663 | ||
664 | static Authmethod * | |
665 | authmethod_lookup(const char *name) | |
666 | { | |
667 | Authmethod *method = NULL; | |
668 | if (name != NULL) | |
669 | for (method = authmethods; method->name != NULL; method++) | |
670 | if (method->enabled != NULL && | |
671 | *(method->enabled) != 0 && | |
672 | strcmp(name, method->name) == 0) | |
673 | return method; | |
674 | debug2("Unrecognized authentication method name: %s", name ? name : "NULL"); | |
675 | return NULL; | |
676 | } | |
677 | ||
678 | /* return 1 if user allows given key */ | |
679 | static int | |
680 | user_key_allowed2(struct passwd *pw, Key *key, char *file) | |
681 | { | |
682 | char line[8192]; | |
683 | int found_key = 0; | |
684 | FILE *f; | |
685 | u_long linenum = 0; | |
686 | struct stat st; | |
687 | Key *found; | |
e9a17296 | 688 | char *fp; |
3c0ef626 | 689 | |
690 | if (pw == NULL) | |
691 | return 0; | |
692 | ||
693 | /* Temporarily use the user's uid. */ | |
694 | temporarily_use_uid(pw); | |
695 | ||
696 | debug("trying public key file %s", file); | |
697 | ||
698 | /* Fail quietly if file does not exist */ | |
699 | if (stat(file, &st) < 0) { | |
700 | /* Restore the privileged uid. */ | |
701 | restore_uid(); | |
702 | return 0; | |
703 | } | |
704 | /* Open the file containing the authorized keys. */ | |
705 | f = fopen(file, "r"); | |
706 | if (!f) { | |
707 | /* Restore the privileged uid. */ | |
708 | restore_uid(); | |
709 | return 0; | |
710 | } | |
711 | if (options.strict_modes && | |
712 | secure_filename(f, file, pw, line, sizeof(line)) != 0) { | |
713 | fclose(f); | |
714 | log("Authentication refused: %s", line); | |
715 | restore_uid(); | |
716 | return 0; | |
717 | } | |
718 | ||
719 | found_key = 0; | |
720 | found = key_new(key->type); | |
721 | ||
722 | while (fgets(line, sizeof(line), f)) { | |
723 | char *cp, *options = NULL; | |
724 | linenum++; | |
725 | /* Skip leading whitespace, empty and comment lines. */ | |
726 | for (cp = line; *cp == ' ' || *cp == '\t'; cp++) | |
727 | ; | |
728 | if (!*cp || *cp == '\n' || *cp == '#') | |
729 | continue; | |
730 | ||
731 | if (key_read(found, &cp) != 1) { | |
732 | /* no key? check if there are options for this key */ | |
733 | int quoted = 0; | |
734 | debug2("user_key_allowed: check options: '%s'", cp); | |
735 | options = cp; | |
736 | for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) { | |
737 | if (*cp == '\\' && cp[1] == '"') | |
738 | cp++; /* Skip both */ | |
739 | else if (*cp == '"') | |
740 | quoted = !quoted; | |
741 | } | |
742 | /* Skip remaining whitespace. */ | |
743 | for (; *cp == ' ' || *cp == '\t'; cp++) | |
744 | ; | |
745 | if (key_read(found, &cp) != 1) { | |
746 | debug2("user_key_allowed: advance: '%s'", cp); | |
747 | /* still no key? advance to next line*/ | |
748 | continue; | |
749 | } | |
750 | } | |
751 | if (key_equal(found, key) && | |
752 | auth_parse_options(pw, options, file, linenum) == 1) { | |
753 | found_key = 1; | |
754 | debug("matching key found: file %s, line %lu", | |
755 | file, linenum); | |
e9a17296 | 756 | fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX); |
757 | verbose("Found matching %s key: %s", | |
758 | key_type(found), fp); | |
759 | xfree(fp); | |
3c0ef626 | 760 | break; |
761 | } | |
762 | } | |
763 | restore_uid(); | |
764 | fclose(f); | |
765 | key_free(found); | |
766 | if (!found_key) | |
767 | debug2("key not found"); | |
768 | return found_key; | |
769 | } | |
770 | ||
771 | /* check whether given key is in .ssh/authorized_keys* */ | |
700318f3 | 772 | int |
3c0ef626 | 773 | user_key_allowed(struct passwd *pw, Key *key) |
774 | { | |
775 | int success; | |
776 | char *file; | |
777 | ||
778 | file = authorized_keys_file(pw); | |
779 | success = user_key_allowed2(pw, key, file); | |
780 | xfree(file); | |
781 | if (success) | |
782 | return success; | |
783 | ||
784 | /* try suffix "2" for backward compat, too */ | |
785 | file = authorized_keys_file2(pw); | |
786 | success = user_key_allowed2(pw, key, file); | |
787 | xfree(file); | |
788 | return success; | |
789 | } | |
790 | ||
791 | /* return 1 if given hostkey is allowed */ | |
700318f3 | 792 | int |
3c0ef626 | 793 | hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost, |
794 | Key *key) | |
795 | { | |
796 | const char *resolvedname, *ipaddr, *lookup; | |
e9a17296 | 797 | HostStatus host_status; |
798 | int len; | |
3c0ef626 | 799 | |
e9a17296 | 800 | resolvedname = get_canonical_hostname(options.verify_reverse_mapping); |
3c0ef626 | 801 | ipaddr = get_remote_ipaddr(); |
802 | ||
803 | debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s", | |
804 | chost, resolvedname, ipaddr); | |
805 | ||
806 | if (options.hostbased_uses_name_from_packet_only) { | |
807 | if (auth_rhosts2(pw, cuser, chost, chost) == 0) | |
808 | return 0; | |
809 | lookup = chost; | |
810 | } else { | |
811 | if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') { | |
812 | debug2("stripping trailing dot from chost %s", chost); | |
813 | chost[len - 1] = '\0'; | |
814 | } | |
815 | if (strcasecmp(resolvedname, chost) != 0) | |
816 | log("userauth_hostbased mismatch: " | |
817 | "client sends %s, but we resolve %s to %s", | |
818 | chost, ipaddr, resolvedname); | |
819 | if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0) | |
820 | return 0; | |
821 | lookup = resolvedname; | |
822 | } | |
823 | debug2("userauth_hostbased: access allowed by auth_rhosts2"); | |
824 | ||
825 | host_status = check_key_in_hostfiles(pw, key, lookup, | |
826 | _PATH_SSH_SYSTEM_HOSTFILE, | |
827 | options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE); | |
828 | ||
829 | /* backward compat if no key has been found. */ | |
830 | if (host_status == HOST_NEW) | |
831 | host_status = check_key_in_hostfiles(pw, key, lookup, | |
832 | _PATH_SSH_SYSTEM_HOSTFILE2, | |
833 | options.ignore_user_known_hosts ? NULL : | |
834 | _PATH_SSH_USER_HOSTFILE2); | |
835 | ||
836 | return (host_status == HOST_OK); | |
837 | } |