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a306f2dd 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.
a306f2dd 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 */
bcbf86ec 24
a306f2dd 25#include "includes.h"
67fa09f5 26RCSID("$OpenBSD: auth2.c,v 1.84 2002/02/04 11:58:10 markus Exp $");
94ec8c6b 27
a306f2dd 28#include <openssl/evp.h>
29
42f11eb2 30#include "ssh2.h"
a306f2dd 31#include "xmalloc.h"
32#include "rsa.h"
1729c161 33#include "sshpty.h"
a306f2dd 34#include "packet.h"
35#include "buffer.h"
42f11eb2 36#include "log.h"
a306f2dd 37#include "servconf.h"
38#include "compat.h"
a5efa1bb 39#include "channels.h"
a306f2dd 40#include "bufaux.h"
a306f2dd 41#include "auth.h"
42#include "session.h"
43#include "dispatch.h"
a306f2dd 44#include "key.h"
b0e305c9 45#include "cipher.h"
a306f2dd 46#include "kex.h"
42f11eb2 47#include "pathnames.h"
a306f2dd 48#include "uidswap.h"
38c295d6 49#include "auth-options.h"
3b1a83df 50#include "misc.h"
8002af61 51#include "hostfile.h"
52#include "canohost.h"
5ba55ada 53#include "match.h"
a306f2dd 54
55/* import */
56extern ServerOptions options;
1e3b8b07 57extern u_char *session_id2;
a306f2dd 58extern int session_id2_len;
59
94ec8c6b 60static Authctxt *x_authctxt = NULL;
61static int one = 1;
62
63typedef struct Authmethod Authmethod;
64struct Authmethod {
65 char *name;
66 int (*userauth)(Authctxt *authctxt);
67 int *enabled;
68};
69
a306f2dd 70/* protocol */
71
7819b5c3 72static void input_service_request(int, u_int32_t, void *);
73static void input_userauth_request(int, u_int32_t, void *);
a306f2dd 74
a306f2dd 75/* helper */
396c147e 76static Authmethod *authmethod_lookup(const char *);
ffb215be 77static char *authmethods_get(void);
396c147e 78static int user_key_allowed(struct passwd *, Key *);
79static int hostbased_key_allowed(struct passwd *, const char *, char *, Key *);
a306f2dd 80
94ec8c6b 81/* auth */
396c147e 82static void userauth_banner(void);
83static int userauth_none(Authctxt *);
84static int userauth_passwd(Authctxt *);
85static int userauth_pubkey(Authctxt *);
86static int userauth_hostbased(Authctxt *);
87static int userauth_kbdint(Authctxt *);
94ec8c6b 88
89Authmethod authmethods[] = {
90 {"none",
91 userauth_none,
92 &one},
93 {"publickey",
94 userauth_pubkey,
fa08c86b 95 &options.pubkey_authentication},
94ec8c6b 96 {"password",
97 userauth_passwd,
98 &options.password_authentication},
c845316f 99 {"keyboard-interactive",
100 userauth_kbdint,
101 &options.kbd_interactive_authentication},
8002af61 102 {"hostbased",
103 userauth_hostbased,
104 &options.hostbased_authentication},
94ec8c6b 105 {NULL, NULL, NULL}
a306f2dd 106};
a306f2dd 107
108/*
94ec8c6b 109 * loop until authctxt->success == TRUE
a306f2dd 110 */
111
112void
d5bb9418 113do_authentication2(void)
a306f2dd 114{
59c97189 115 Authctxt *authctxt = authctxt_new();
116
94ec8c6b 117 x_authctxt = authctxt; /*XXX*/
118
aa8003d6 119 /* challenge-response is implemented via keyboard interactive */
5ba55ada 120 if (options.challenge_response_authentication)
d464095c 121 options.kbd_interactive_authentication = 1;
10f72868 122 if (options.pam_authentication_via_kbd_int)
123 options.kbd_interactive_authentication = 1;
d464095c 124
6367063f 125 dispatch_init(&dispatch_protocol_error);
a306f2dd 126 dispatch_set(SSH2_MSG_SERVICE_REQUEST, &input_service_request);
94ec8c6b 127 dispatch_run(DISPATCH_BLOCK, &authctxt->success, authctxt);
bb5639fe 128 do_authenticated(authctxt);
a306f2dd 129}
130
396c147e 131static void
7819b5c3 132input_service_request(int type, u_int32_t seq, void *ctxt)
a306f2dd 133{
94ec8c6b 134 Authctxt *authctxt = ctxt;
1e3b8b07 135 u_int len;
a306f2dd 136 int accept = 0;
137 char *service = packet_get_string(&len);
95500969 138 packet_check_eom();
a306f2dd 139
94ec8c6b 140 if (authctxt == NULL)
141 fatal("input_service_request: no authctxt");
142
a306f2dd 143 if (strcmp(service, "ssh-userauth") == 0) {
94ec8c6b 144 if (!authctxt->success) {
a306f2dd 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
396c147e 164static void
7819b5c3 165input_userauth_request(int type, u_int32_t seq, void *ctxt)
a306f2dd 166{
94ec8c6b 167 Authctxt *authctxt = ctxt;
168 Authmethod *m = NULL;
59c97189 169 char *user, *service, *method, *style = NULL;
a306f2dd 170 int authenticated = 0;
a306f2dd 171
94ec8c6b 172 if (authctxt == NULL)
173 fatal("input_userauth_request: no authctxt");
a306f2dd 174
94ec8c6b 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);
8abcdba4 179 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
94ec8c6b 180
59c97189 181 if ((style = strchr(user, ':')) != NULL)
182 *style++ = 0;
183
2b87da3b 184 if (authctxt->attempt++ == 0) {
94ec8c6b 185 /* setup auth context */
186 struct passwd *pw = NULL;
94ec8c6b 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
04fc7a67 193 start_pam(pw->pw_name);
94ec8c6b 194#endif
195 } else {
196 log("input_userauth_request: illegal user %s", user);
04fc7a67 197#ifdef USE_PAM
198 start_pam("NOUSER");
199#endif
94ec8c6b 200 }
6172e290 201 setproctitle("%s", pw ? user : "unknown");
94ec8c6b 202 authctxt->user = xstrdup(user);
203 authctxt->service = xstrdup(service);
2a6a054e 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);
a306f2dd 210 }
59c97189 211 /* reset state */
2f293d43 212 auth2_challenge_stop(authctxt);
59c97189 213 authctxt->postponed = 0;
9cd45ea4 214
59c97189 215 /* try to authenticate user */
94ec8c6b 216 m = authmethod_lookup(method);
217 if (m != NULL) {
218 debug2("input_userauth_request: try method %s", method);
219 authenticated = m->userauth(authctxt);
9cd45ea4 220 }
d9cd3575 221 userauth_finish(authctxt, authenticated, method);
222
223 xfree(service);
224 xfree(user);
225 xfree(method);
226}
227
228void
229userauth_finish(Authctxt *authctxt, int authenticated, char *method)
230{
4e81159c 231 char *methods;
232
59c97189 233 if (!authctxt->valid && authenticated)
234 fatal("INTERNAL ERROR: authenticated invalid user %s",
235 authctxt->user);
9cd45ea4 236
94ec8c6b 237 /* Special handling for root */
15853e93 238 if (authenticated && authctxt->pw->pw_uid == 0 &&
239 !auth_root_allowed(method))
a306f2dd 240 authenticated = 0;
a306f2dd 241
242#ifdef USE_PAM
edef62bf 243 if (authenticated && authctxt->user && !do_pam_account(authctxt->user,
244 NULL))
9cd45ea4 245 authenticated = 0;
a306f2dd 246#endif /* USE_PAM */
247
94ec8c6b 248 /* Log before sending the reply */
59c97189 249 auth_log(authctxt, authenticated, method, " ssh2");
250
4e81159c 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 */
6367063f 257 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
4e81159c 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 {
19e810f6 264 if (authctxt->failures++ > AUTH_FAIL_MAX) {
265#ifdef WITH_AIXAUTHENTICATE
266 loginfailed(authctxt->user,
983784a1 267 get_canonical_hostname(options.verify_reverse_mapping),
19e810f6 268 "ssh");
269#endif /* WITH_AIXAUTHENTICATE */
4e81159c 270 packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
19e810f6 271 }
4e81159c 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 }
94ec8c6b 280}
281
396c147e 282static void
eea39c02 283userauth_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;
0715ec6c 292 if ((fd = open(options.banner, O_RDONLY)) < 0)
eea39c02 293 return;
eea39c02 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");
306done:
307 if (banner)
308 xfree(banner);
309 close(fd);
310 return;
311}
94ec8c6b 312
396c147e 313static int
94ec8c6b 314userauth_none(Authctxt *authctxt)
a306f2dd 315{
94ec8c6b 316 /* disable method "none", only allowed one time */
317 Authmethod *m = authmethod_lookup("none");
318 if (m != NULL)
319 m->enabled = NULL;
95500969 320 packet_check_eom();
2b87da3b 321 userauth_banner();
4d33e531 322
94ec8c6b 323 if (authctxt->valid == 0)
324 return(0);
2b87da3b 325
94ec8c6b 326#ifdef HAVE_CYGWIN
e9571a2c 327 if (check_nt_auth(1, authctxt->pw) == 0)
94ec8c6b 328 return(0);
329#endif
a306f2dd 330#ifdef USE_PAM
94ec8c6b 331 return auth_pam_password(authctxt->pw, "");
4d33e531 332#elif defined(HAVE_OSF_SIA)
b7ccb051 333 return 0;
4d33e531 334#else /* !HAVE_OSF_SIA && !USE_PAM */
af774732 335 return auth_password(authctxt, "");
a306f2dd 336#endif /* USE_PAM */
337}
94ec8c6b 338
396c147e 339static int
94ec8c6b 340userauth_passwd(Authctxt *authctxt)
a306f2dd 341{
342 char *password;
343 int authenticated = 0;
344 int change;
1e3b8b07 345 u_int len;
a306f2dd 346 change = packet_get_char();
347 if (change)
348 log("password change not supported");
349 password = packet_get_string(&len);
95500969 350 packet_check_eom();
94ec8c6b 351 if (authctxt->valid &&
352#ifdef HAVE_CYGWIN
e9571a2c 353 check_nt_auth(1, authctxt->pw) &&
94ec8c6b 354#endif
a306f2dd 355#ifdef USE_PAM
94ec8c6b 356 auth_pam_password(authctxt->pw, password) == 1)
4d33e531 357#elif defined(HAVE_OSF_SIA)
b7ccb051 358 auth_sia_password(authctxt->user, password) == 1)
4d33e531 359#else /* !USE_PAM && !HAVE_OSF_SIA */
af774732 360 auth_password(authctxt, password) == 1)
a306f2dd 361#endif /* USE_PAM */
362 authenticated = 1;
363 memset(password, 0, len);
364 xfree(password);
365 return authenticated;
366}
94ec8c6b 367
396c147e 368static int
94ec8c6b 369userauth_kbdint(Authctxt *authctxt)
370{
371 int authenticated = 0;
5ba55ada 372 char *lang, *devs;
94ec8c6b 373
374 lang = packet_get_string(NULL);
375 devs = packet_get_string(NULL);
95500969 376 packet_check_eom();
94ec8c6b 377
5ba55ada 378 debug("keyboard-interactive devs %s", devs);
59c97189 379
5ba55ada 380 if (options.challenge_response_authentication)
d464095c 381 authenticated = auth2_challenge(authctxt, devs);
59c97189 382
8c9fe09e 383#ifdef USE_PAM
10f72868 384 if (authenticated == 0 && options.pam_authentication_via_kbd_int)
8c9fe09e 385 authenticated = auth2_pam(authctxt);
94ec8c6b 386#endif
94ec8c6b 387 xfree(devs);
5ba55ada 388 xfree(lang);
94ec8c6b 389#ifdef HAVE_CYGWIN
e9571a2c 390 if (check_nt_auth(0, authctxt->pw) == 0)
94ec8c6b 391 return(0);
392#endif
393 return authenticated;
394}
395
396c147e 396static int
94ec8c6b 397userauth_pubkey(Authctxt *authctxt)
a306f2dd 398{
399 Buffer b;
67fa09f5 400 Key *key = NULL;
a306f2dd 401 char *pkalg, *pkblob, *sig;
1e3b8b07 402 u_int alen, blen, slen;
fa08c86b 403 int have_sig, pktype;
a306f2dd 404 int authenticated = 0;
405
94ec8c6b 406 if (!authctxt->valid) {
407 debug2("userauth_pubkey: disabled because of invalid user");
a306f2dd 408 return 0;
409 }
410 have_sig = packet_get_char();
cbc5abf9 411 if (datafellows & SSH_BUG_PKAUTH) {
412 debug2("userauth_pubkey: SSH_BUG_PKAUTH");
413 /* no explicit pkalg given */
414 pkblob = packet_get_string(&blen);
415 buffer_init(&b);
416 buffer_append(&b, pkblob, blen);
417 /* so we have to extract the pkalg from the pkblob */
418 pkalg = buffer_get_string(&b, &alen);
419 buffer_free(&b);
420 } else {
421 pkalg = packet_get_string(&alen);
422 pkblob = packet_get_string(&blen);
423 }
fa08c86b 424 pktype = key_type_from_name(pkalg);
425 if (pktype == KEY_UNSPEC) {
cbc5abf9 426 /* this is perfectly legal */
67fa09f5 427 log("userauth_pubkey: unsupported public key algorithm: %s",
428 pkalg);
429 goto done;
a306f2dd 430 }
fa08c86b 431 key = key_from_blob(pkblob, blen);
67fa09f5 432 if (key == NULL) {
433 error("userauth_pubkey: cannot decode key: %s", pkalg);
434 goto done;
435 }
436 if (key->type != pktype) {
437 error("userauth_pubkey: type mismatch for decoded key "
438 "(received %d, expected %d)", key->type, pktype);
439 goto done;
440 }
441 if (have_sig) {
442 sig = packet_get_string(&slen);
443 packet_check_eom();
444 buffer_init(&b);
445 if (datafellows & SSH_OLD_SESSIONID) {
446 buffer_append(&b, session_id2, session_id2_len);
447 } else {
448 buffer_put_string(&b, session_id2, session_id2_len);
449 }
450 /* reconstruct packet */
451 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
452 buffer_put_cstring(&b, authctxt->user);
453 buffer_put_cstring(&b,
454 datafellows & SSH_BUG_PKSERVICE ?
455 "ssh-userauth" :
456 authctxt->service);
457 if (datafellows & SSH_BUG_PKAUTH) {
458 buffer_put_char(&b, have_sig);
459 } else {
460 buffer_put_cstring(&b, "publickey");
461 buffer_put_char(&b, have_sig);
462 buffer_put_cstring(&b, pkalg);
463 }
464 buffer_put_string(&b, pkblob, blen);
fa08c86b 465#ifdef DEBUG_PK
67fa09f5 466 buffer_dump(&b);
a306f2dd 467#endif
67fa09f5 468 /* test for correct signature */
469 if (user_key_allowed(authctxt->pw, key) &&
470 key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
471 authenticated = 1;
472 buffer_clear(&b);
473 xfree(sig);
474 } else {
475 debug("test whether pkalg/pkblob are acceptable");
476 packet_check_eom();
477
478 /* XXX fake reply and always send PK_OK ? */
479 /*
480 * XXX this allows testing whether a user is allowed
481 * to login: if you happen to have a valid pubkey this
482 * message is sent. the message is NEVER sent at all
483 * if a user is not allowed to login. is this an
484 * issue? -markus
485 */
486 if (user_key_allowed(authctxt->pw, key)) {
487 packet_start(SSH2_MSG_USERAUTH_PK_OK);
488 packet_put_string(pkalg, alen);
489 packet_put_string(pkblob, blen);
490 packet_send();
491 packet_write_wait();
492 authctxt->postponed = 1;
a306f2dd 493 }
a306f2dd 494 }
67fa09f5 495 if (authenticated != 1)
496 auth_clear_options();
497done:
fa08c86b 498 debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
67fa09f5 499 if (key != NULL)
500 key_free(key);
a306f2dd 501 xfree(pkalg);
502 xfree(pkblob);
94ec8c6b 503#ifdef HAVE_CYGWIN
e9571a2c 504 if (check_nt_auth(0, authctxt->pw) == 0)
94ec8c6b 505 return(0);
506#endif
a306f2dd 507 return authenticated;
508}
509
396c147e 510static int
8002af61 511userauth_hostbased(Authctxt *authctxt)
512{
513 Buffer b;
67fa09f5 514 Key *key = NULL;
8dddf799 515 char *pkalg, *pkblob, *sig, *cuser, *chost, *service;
8002af61 516 u_int alen, blen, slen;
517 int pktype;
518 int authenticated = 0;
519
520 if (!authctxt->valid) {
521 debug2("userauth_hostbased: disabled because of invalid user");
522 return 0;
523 }
524 pkalg = packet_get_string(&alen);
525 pkblob = packet_get_string(&blen);
526 chost = packet_get_string(NULL);
527 cuser = packet_get_string(NULL);
528 sig = packet_get_string(&slen);
529
530 debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
531 cuser, chost, pkalg, slen);
532#ifdef DEBUG_PK
533 debug("signature:");
534 buffer_init(&b);
535 buffer_append(&b, sig, slen);
536 buffer_dump(&b);
537 buffer_free(&b);
538#endif
539 pktype = key_type_from_name(pkalg);
540 if (pktype == KEY_UNSPEC) {
541 /* this is perfectly legal */
542 log("userauth_hostbased: unsupported "
543 "public key algorithm: %s", pkalg);
544 goto done;
545 }
546 key = key_from_blob(pkblob, blen);
547 if (key == NULL) {
67fa09f5 548 error("userauth_hostbased: cannot decode key: %s", pkalg);
549 goto done;
550 }
551 if (key->type != pktype) {
552 error("userauth_hostbased: type mismatch for decoded key "
553 "(received %d, expected %d)", key->type, pktype);
8002af61 554 goto done;
555 }
8dddf799 556 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
557 authctxt->service;
8002af61 558 buffer_init(&b);
8dddf799 559 buffer_put_string(&b, session_id2, session_id2_len);
8002af61 560 /* reconstruct packet */
561 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
562 buffer_put_cstring(&b, authctxt->user);
8dddf799 563 buffer_put_cstring(&b, service);
8002af61 564 buffer_put_cstring(&b, "hostbased");
565 buffer_put_string(&b, pkalg, alen);
566 buffer_put_string(&b, pkblob, blen);
567 buffer_put_cstring(&b, chost);
568 buffer_put_cstring(&b, cuser);
569#ifdef DEBUG_PK
570 buffer_dump(&b);
571#endif
572 /* test for allowed key and correct signature */
573 if (hostbased_key_allowed(authctxt->pw, cuser, chost, key) &&
574 key_verify(key, sig, slen, buffer_ptr(&b), buffer_len(&b)) == 1)
575 authenticated = 1;
576
577 buffer_clear(&b);
8002af61 578done:
579 debug2("userauth_hostbased: authenticated %d", authenticated);
67fa09f5 580 if (key != NULL)
581 key_free(key);
8002af61 582 xfree(pkalg);
583 xfree(pkblob);
584 xfree(cuser);
585 xfree(chost);
586 xfree(sig);
587 return authenticated;
588}
589
94ec8c6b 590/* get current user */
a306f2dd 591
592struct passwd*
593auth_get_user(void)
594{
94ec8c6b 595 return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL;
a306f2dd 596}
597
94ec8c6b 598#define DELIM ","
599
ffb215be 600static char *
94ec8c6b 601authmethods_get(void)
a306f2dd 602{
94ec8c6b 603 Authmethod *method = NULL;
3469eac4 604 Buffer b;
94ec8c6b 605 char *list;
606
3469eac4 607 buffer_init(&b);
94ec8c6b 608 for (method = authmethods; method->name != NULL; method++) {
609 if (strcmp(method->name, "none") == 0)
610 continue;
611 if (method->enabled != NULL && *(method->enabled) != 0) {
3469eac4 612 if (buffer_len(&b) > 0)
613 buffer_append(&b, ",", 1);
614 buffer_append(&b, method->name, strlen(method->name));
a306f2dd 615 }
616 }
3469eac4 617 buffer_append(&b, "\0", 1);
618 list = xstrdup(buffer_ptr(&b));
619 buffer_free(&b);
94ec8c6b 620 return list;
621}
622
396c147e 623static Authmethod *
94ec8c6b 624authmethod_lookup(const char *name)
625{
626 Authmethod *method = NULL;
627 if (name != NULL)
628 for (method = authmethods; method->name != NULL; method++)
629 if (method->enabled != NULL &&
630 *(method->enabled) != 0 &&
631 strcmp(name, method->name) == 0)
632 return method;
633 debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
634 return NULL;
a306f2dd 635}
636
637/* return 1 if user allows given key */
396c147e 638static int
96a7b0cc 639user_key_allowed2(struct passwd *pw, Key *key, char *file)
a306f2dd 640{
96a7b0cc 641 char line[8192];
a306f2dd 642 int found_key = 0;
a306f2dd 643 FILE *f;
1e3b8b07 644 u_long linenum = 0;
a306f2dd 645 struct stat st;
646 Key *found;
306feb91 647 char *fp;
a306f2dd 648
94ec8c6b 649 if (pw == NULL)
650 return 0;
651
a306f2dd 652 /* Temporarily use the user's uid. */
63bd8c36 653 temporarily_use_uid(pw);
a306f2dd 654
c8445989 655 debug("trying public key file %s", file);
a306f2dd 656
657 /* Fail quietly if file does not exist */
658 if (stat(file, &st) < 0) {
659 /* Restore the privileged uid. */
660 restore_uid();
661 return 0;
662 }
663 /* Open the file containing the authorized keys. */
664 f = fopen(file, "r");
665 if (!f) {
666 /* Restore the privileged uid. */
667 restore_uid();
668 return 0;
669 }
c8445989 670 if (options.strict_modes &&
0c9664c2 671 secure_filename(f, file, pw, line, sizeof(line)) != 0) {
c8445989 672 fclose(f);
673 log("Authentication refused: %s", line);
674 restore_uid();
675 return 0;
a306f2dd 676 }
c8445989 677
a306f2dd 678 found_key = 0;
de273eef 679 found = key_new(key->type);
a306f2dd 680
681 while (fgets(line, sizeof(line), f)) {
38c295d6 682 char *cp, *options = NULL;
a306f2dd 683 linenum++;
684 /* Skip leading whitespace, empty and comment lines. */
685 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
686 ;
687 if (!*cp || *cp == '\n' || *cp == '#')
688 continue;
38c295d6 689
ddcfed57 690 if (key_read(found, &cp) != 1) {
38c295d6 691 /* no key? check if there are options for this key */
692 int quoted = 0;
fa08c86b 693 debug2("user_key_allowed: check options: '%s'", cp);
38c295d6 694 options = cp;
695 for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
696 if (*cp == '\\' && cp[1] == '"')
697 cp++; /* Skip both */
698 else if (*cp == '"')
699 quoted = !quoted;
700 }
701 /* Skip remaining whitespace. */
702 for (; *cp == ' ' || *cp == '\t'; cp++)
703 ;
ddcfed57 704 if (key_read(found, &cp) != 1) {
fa08c86b 705 debug2("user_key_allowed: advance: '%s'", cp);
38c295d6 706 /* still no key? advance to next line*/
707 continue;
708 }
709 }
710 if (key_equal(found, key) &&
42f11eb2 711 auth_parse_options(pw, options, file, linenum) == 1) {
a306f2dd 712 found_key = 1;
1bdee08c 713 debug("matching key found: file %s, line %lu",
a306f2dd 714 file, linenum);
306feb91 715 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
716 verbose("Found matching %s key: %s",
184eed6a 717 key_type(found), fp);
306feb91 718 xfree(fp);
a306f2dd 719 break;
720 }
721 }
722 restore_uid();
723 fclose(f);
724 key_free(found);
539af7f5 725 if (!found_key)
726 debug2("key not found");
a306f2dd 727 return found_key;
728}
8002af61 729
96a7b0cc 730/* check whether given key is in .ssh/authorized_keys* */
396c147e 731static int
96a7b0cc 732user_key_allowed(struct passwd *pw, Key *key)
733{
734 int success;
735 char *file;
736
737 file = authorized_keys_file(pw);
738 success = user_key_allowed2(pw, key, file);
739 xfree(file);
740 if (success)
741 return success;
742
743 /* try suffix "2" for backward compat, too */
744 file = authorized_keys_file2(pw);
745 success = user_key_allowed2(pw, key, file);
746 xfree(file);
747 return success;
748}
749
8002af61 750/* return 1 if given hostkey is allowed */
396c147e 751static int
57a5edd8 752hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
8002af61 753 Key *key)
754{
8002af61 755 const char *resolvedname, *ipaddr, *lookup;
17a3011c 756 HostStatus host_status;
757 int len;
8002af61 758
bf4c5edc 759 resolvedname = get_canonical_hostname(options.verify_reverse_mapping);
8002af61 760 ipaddr = get_remote_ipaddr();
761
f98c3421 762 debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s",
763 chost, resolvedname, ipaddr);
8002af61 764
765 if (options.hostbased_uses_name_from_packet_only) {
766 if (auth_rhosts2(pw, cuser, chost, chost) == 0)
767 return 0;
768 lookup = chost;
769 } else {
f98c3421 770 if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
771 debug2("stripping trailing dot from chost %s", chost);
772 chost[len - 1] = '\0';
773 }
8002af61 774 if (strcasecmp(resolvedname, chost) != 0)
775 log("userauth_hostbased mismatch: "
776 "client sends %s, but we resolve %s to %s",
777 chost, ipaddr, resolvedname);
778 if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0)
779 return 0;
780 lookup = resolvedname;
781 }
782 debug2("userauth_hostbased: access allowed by auth_rhosts2");
783
d0c8ca5c 784 host_status = check_key_in_hostfiles(pw, key, lookup,
785 _PATH_SSH_SYSTEM_HOSTFILE,
73473230 786 options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
d0c8ca5c 787
788 /* backward compat if no key has been found. */
789 if (host_status == HOST_NEW)
790 host_status = check_key_in_hostfiles(pw, key, lookup,
791 _PATH_SSH_SYSTEM_HOSTFILE2,
73473230 792 options.ignore_user_known_hosts ? NULL :
793 _PATH_SSH_USER_HOSTFILE2);
8002af61 794
8002af61 795 return (host_status == HOST_OK);
796}
d0c8ca5c 797
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