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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"
5f1f36b5 26RCSID("$OpenBSD: auth2.c,v 1.89 2002/03/19 14:27:39 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"
8002af61 50#include "hostfile.h"
51#include "canohost.h"
5ba55ada 52#include "match.h"
1853d1ef 53#include "monitor_wrap.h"
a306f2dd 54
55/* import */
56extern ServerOptions options;
1e3b8b07 57extern u_char *session_id2;
a306f2dd 58extern int session_id2_len;
59
1853d1ef 60Authctxt *x_authctxt = NULL;
94ec8c6b 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);
1853d1ef 78int user_key_allowed(struct passwd *, Key *);
79int 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
1b34c1b3 112Authctxt *
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);
1b34c1b3 128
129 return (authctxt);
a306f2dd 130}
131
396c147e 132static void
7819b5c3 133input_service_request(int type, u_int32_t seq, void *ctxt)
a306f2dd 134{
94ec8c6b 135 Authctxt *authctxt = ctxt;
1e3b8b07 136 u_int len;
a306f2dd 137 int accept = 0;
138 char *service = packet_get_string(&len);
95500969 139 packet_check_eom();
a306f2dd 140
94ec8c6b 141 if (authctxt == NULL)
142 fatal("input_service_request: no authctxt");
143
a306f2dd 144 if (strcmp(service, "ssh-userauth") == 0) {
94ec8c6b 145 if (!authctxt->success) {
a306f2dd 146 accept = 1;
147 /* now we can handle user-auth requests */
148 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request);
149 }
150 }
151 /* XXX all other service requests are denied */
152
153 if (accept) {
154 packet_start(SSH2_MSG_SERVICE_ACCEPT);
155 packet_put_cstring(service);
156 packet_send();
157 packet_write_wait();
158 } else {
159 debug("bad service request %s", service);
160 packet_disconnect("bad service request %s", service);
161 }
162 xfree(service);
163}
164
396c147e 165static void
7819b5c3 166input_userauth_request(int type, u_int32_t seq, void *ctxt)
a306f2dd 167{
94ec8c6b 168 Authctxt *authctxt = ctxt;
169 Authmethod *m = NULL;
59c97189 170 char *user, *service, *method, *style = NULL;
a306f2dd 171 int authenticated = 0;
a306f2dd 172
94ec8c6b 173 if (authctxt == NULL)
174 fatal("input_userauth_request: no authctxt");
a306f2dd 175
94ec8c6b 176 user = packet_get_string(NULL);
177 service = packet_get_string(NULL);
178 method = packet_get_string(NULL);
179 debug("userauth-request for user %s service %s method %s", user, service, method);
8abcdba4 180 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
94ec8c6b 181
59c97189 182 if ((style = strchr(user, ':')) != NULL)
183 *style++ = 0;
184
2b87da3b 185 if (authctxt->attempt++ == 0) {
63284fbb 186 /* setup auth context */
f7ed12f1 187 authctxt->pw = PRIVSEP(getpwnamallow(user));
188 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
94ec8c6b 189 authctxt->valid = 1;
190 debug2("input_userauth_request: setting up authctxt for %s", user);
191#ifdef USE_PAM
f7ed12f1 192 start_pam(authctxt->pw->pw_name);
94ec8c6b 193#endif
194 } else {
195 log("input_userauth_request: illegal user %s", user);
04fc7a67 196#ifdef USE_PAM
197 start_pam("NOUSER");
198#endif
94ec8c6b 199 }
5f1f36b5 200 setproctitle("%s%s", authctxt->pw ? user : "unknown",
1853d1ef 201 use_privsep ? " [net]" : "");
94ec8c6b 202 authctxt->user = xstrdup(user);
203 authctxt->service = xstrdup(service);
2a6a054e 204 authctxt->style = style ? xstrdup(style) : NULL;
1853d1ef 205 if (use_privsep)
206 mm_inform_authserv(service, style);
2a6a054e 207 } else if (strcmp(user, authctxt->user) != 0 ||
208 strcmp(service, authctxt->service) != 0) {
209 packet_disconnect("Change of username or service not allowed: "
210 "(%s,%s) -> (%s,%s)",
211 authctxt->user, authctxt->service, user, service);
a306f2dd 212 }
59c97189 213 /* reset state */
2f293d43 214 auth2_challenge_stop(authctxt);
59c97189 215 authctxt->postponed = 0;
9cd45ea4 216
59c97189 217 /* try to authenticate user */
94ec8c6b 218 m = authmethod_lookup(method);
219 if (m != NULL) {
220 debug2("input_userauth_request: try method %s", method);
221 authenticated = m->userauth(authctxt);
9cd45ea4 222 }
d9cd3575 223 userauth_finish(authctxt, authenticated, method);
224
225 xfree(service);
226 xfree(user);
227 xfree(method);
228}
229
230void
231userauth_finish(Authctxt *authctxt, int authenticated, char *method)
232{
4e81159c 233 char *methods;
234
59c97189 235 if (!authctxt->valid && authenticated)
236 fatal("INTERNAL ERROR: authenticated invalid user %s",
237 authctxt->user);
9cd45ea4 238
94ec8c6b 239 /* Special handling for root */
15853e93 240 if (authenticated && authctxt->pw->pw_uid == 0 &&
241 !auth_root_allowed(method))
a306f2dd 242 authenticated = 0;
a306f2dd 243
244#ifdef USE_PAM
edef62bf 245 if (authenticated && authctxt->user && !do_pam_account(authctxt->user,
246 NULL))
9cd45ea4 247 authenticated = 0;
a306f2dd 248#endif /* USE_PAM */
249
94ec8c6b 250 /* Log before sending the reply */
59c97189 251 auth_log(authctxt, authenticated, method, " ssh2");
252
4e81159c 253 if (authctxt->postponed)
254 return;
255
256 /* XXX todo: check if multiple auth methods are needed */
257 if (authenticated == 1) {
258 /* turn off userauth */
6367063f 259 dispatch_set(SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore);
4e81159c 260 packet_start(SSH2_MSG_USERAUTH_SUCCESS);
261 packet_send();
262 packet_write_wait();
263 /* now we can break out */
264 authctxt->success = 1;
265 } else {
19e810f6 266 if (authctxt->failures++ > AUTH_FAIL_MAX) {
267#ifdef WITH_AIXAUTHENTICATE
268 loginfailed(authctxt->user,
983784a1 269 get_canonical_hostname(options.verify_reverse_mapping),
19e810f6 270 "ssh");
271#endif /* WITH_AIXAUTHENTICATE */
4e81159c 272 packet_disconnect(AUTH_FAIL_MSG, authctxt->user);
19e810f6 273 }
4e81159c 274 methods = authmethods_get();
275 packet_start(SSH2_MSG_USERAUTH_FAILURE);
276 packet_put_cstring(methods);
277 packet_put_char(0); /* XXX partial success, unused */
278 packet_send();
279 packet_write_wait();
280 xfree(methods);
281 }
94ec8c6b 282}
283
396c147e 284static void
eea39c02 285userauth_banner(void)
286{
287 struct stat st;
288 char *banner = NULL;
289 off_t len, n;
290 int fd;
291
292 if (options.banner == NULL || (datafellows & SSH_BUG_BANNER))
293 return;
0715ec6c 294 if ((fd = open(options.banner, O_RDONLY)) < 0)
eea39c02 295 return;
eea39c02 296 if (fstat(fd, &st) < 0)
297 goto done;
298 len = st.st_size;
299 banner = xmalloc(len + 1);
300 if ((n = read(fd, banner, len)) < 0)
301 goto done;
302 banner[n] = '\0';
303 packet_start(SSH2_MSG_USERAUTH_BANNER);
304 packet_put_cstring(banner);
305 packet_put_cstring(""); /* language, unused */
306 packet_send();
307 debug("userauth_banner: sent");
308done:
309 if (banner)
310 xfree(banner);
311 close(fd);
312 return;
313}
94ec8c6b 314
396c147e 315static int
94ec8c6b 316userauth_none(Authctxt *authctxt)
a306f2dd 317{
94ec8c6b 318 /* disable method "none", only allowed one time */
319 Authmethod *m = authmethod_lookup("none");
320 if (m != NULL)
321 m->enabled = NULL;
95500969 322 packet_check_eom();
2b87da3b 323 userauth_banner();
4d33e531 324
94ec8c6b 325 if (authctxt->valid == 0)
326 return(0);
63284fbb 327
328#ifdef HAVE_CYGWIN
329 if (check_nt_auth(1, authctxt->pw) == 0)
330 return(0);
94ec8c6b 331#endif
63284fbb 332#ifdef USE_PAM
333 return auth_pam_password(authctxt->pw, "");
334#elif defined(HAVE_OSF_SIA)
335 return 0;
336#else /* !HAVE_OSF_SIA && !USE_PAM */
1853d1ef 337 return PRIVSEP(auth_password(authctxt, ""));
63284fbb 338#endif /* USE_PAM */
a306f2dd 339}
94ec8c6b 340
396c147e 341static int
94ec8c6b 342userauth_passwd(Authctxt *authctxt)
a306f2dd 343{
344 char *password;
345 int authenticated = 0;
346 int change;
1e3b8b07 347 u_int len;
a306f2dd 348 change = packet_get_char();
349 if (change)
350 log("password change not supported");
351 password = packet_get_string(&len);
95500969 352 packet_check_eom();
63284fbb 353 if (authctxt->valid &&
354#ifdef HAVE_CYGWIN
355 check_nt_auth(1, authctxt->pw) &&
94ec8c6b 356#endif
63284fbb 357#ifdef USE_PAM
358 auth_pam_password(authctxt->pw, password) == 1)
359#elif defined(HAVE_OSF_SIA)
360 auth_sia_password(authctxt->user, password) == 1)
361#else /* !USE_PAM && !HAVE_OSF_SIA */
1853d1ef 362 PRIVSEP(auth_password(authctxt, password)) == 1)
63284fbb 363#endif /* USE_PAM */
364 authenticated = 1;
a306f2dd 365 memset(password, 0, len);
366 xfree(password);
367 return authenticated;
368}
94ec8c6b 369
396c147e 370static int
94ec8c6b 371userauth_kbdint(Authctxt *authctxt)
372{
373 int authenticated = 0;
5ba55ada 374 char *lang, *devs;
94ec8c6b 375
376 lang = packet_get_string(NULL);
377 devs = packet_get_string(NULL);
95500969 378 packet_check_eom();
94ec8c6b 379
5ba55ada 380 debug("keyboard-interactive devs %s", devs);
59c97189 381
5ba55ada 382 if (options.challenge_response_authentication)
d464095c 383 authenticated = auth2_challenge(authctxt, devs);
59c97189 384
8c9fe09e 385#ifdef USE_PAM
10f72868 386 if (authenticated == 0 && options.pam_authentication_via_kbd_int)
8c9fe09e 387 authenticated = auth2_pam(authctxt);
94ec8c6b 388#endif
94ec8c6b 389 xfree(devs);
5ba55ada 390 xfree(lang);
94ec8c6b 391#ifdef HAVE_CYGWIN
e9571a2c 392 if (check_nt_auth(0, authctxt->pw) == 0)
94ec8c6b 393 return(0);
394#endif
395 return authenticated;
396}
397
396c147e 398static int
94ec8c6b 399userauth_pubkey(Authctxt *authctxt)
a306f2dd 400{
401 Buffer b;
67fa09f5 402 Key *key = NULL;
c66f9d0e 403 char *pkalg;
404 u_char *pkblob, *sig;
1e3b8b07 405 u_int alen, blen, slen;
fa08c86b 406 int have_sig, pktype;
a306f2dd 407 int authenticated = 0;
408
94ec8c6b 409 if (!authctxt->valid) {
410 debug2("userauth_pubkey: disabled because of invalid user");
a306f2dd 411 return 0;
412 }
413 have_sig = packet_get_char();
cbc5abf9 414 if (datafellows & SSH_BUG_PKAUTH) {
415 debug2("userauth_pubkey: SSH_BUG_PKAUTH");
416 /* no explicit pkalg given */
417 pkblob = packet_get_string(&blen);
418 buffer_init(&b);
419 buffer_append(&b, pkblob, blen);
420 /* so we have to extract the pkalg from the pkblob */
421 pkalg = buffer_get_string(&b, &alen);
422 buffer_free(&b);
423 } else {
424 pkalg = packet_get_string(&alen);
425 pkblob = packet_get_string(&blen);
426 }
fa08c86b 427 pktype = key_type_from_name(pkalg);
428 if (pktype == KEY_UNSPEC) {
cbc5abf9 429 /* this is perfectly legal */
67fa09f5 430 log("userauth_pubkey: unsupported public key algorithm: %s",
431 pkalg);
432 goto done;
a306f2dd 433 }
fa08c86b 434 key = key_from_blob(pkblob, blen);
67fa09f5 435 if (key == NULL) {
436 error("userauth_pubkey: cannot decode key: %s", pkalg);
437 goto done;
438 }
439 if (key->type != pktype) {
440 error("userauth_pubkey: type mismatch for decoded key "
441 "(received %d, expected %d)", key->type, pktype);
442 goto done;
443 }
444 if (have_sig) {
445 sig = packet_get_string(&slen);
446 packet_check_eom();
447 buffer_init(&b);
448 if (datafellows & SSH_OLD_SESSIONID) {
449 buffer_append(&b, session_id2, session_id2_len);
450 } else {
451 buffer_put_string(&b, session_id2, session_id2_len);
452 }
453 /* reconstruct packet */
454 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
455 buffer_put_cstring(&b, authctxt->user);
456 buffer_put_cstring(&b,
457 datafellows & SSH_BUG_PKSERVICE ?
458 "ssh-userauth" :
459 authctxt->service);
460 if (datafellows & SSH_BUG_PKAUTH) {
461 buffer_put_char(&b, have_sig);
462 } else {
463 buffer_put_cstring(&b, "publickey");
464 buffer_put_char(&b, have_sig);
465 buffer_put_cstring(&b, pkalg);
466 }
467 buffer_put_string(&b, pkblob, blen);
fa08c86b 468#ifdef DEBUG_PK
67fa09f5 469 buffer_dump(&b);
a306f2dd 470#endif
67fa09f5 471 /* test for correct signature */
1853d1ef 472 authenticated = 0;
473 if (PRIVSEP(user_key_allowed(authctxt->pw, key)) &&
474 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
475 buffer_len(&b))) == 1)
63284fbb 476 authenticated = 1;
67fa09f5 477 buffer_clear(&b);
478 xfree(sig);
479 } else {
480 debug("test whether pkalg/pkblob are acceptable");
481 packet_check_eom();
482
483 /* XXX fake reply and always send PK_OK ? */
484 /*
485 * XXX this allows testing whether a user is allowed
486 * to login: if you happen to have a valid pubkey this
487 * message is sent. the message is NEVER sent at all
488 * if a user is not allowed to login. is this an
489 * issue? -markus
490 */
1853d1ef 491 if (PRIVSEP(user_key_allowed(authctxt->pw, key))) {
67fa09f5 492 packet_start(SSH2_MSG_USERAUTH_PK_OK);
493 packet_put_string(pkalg, alen);
494 packet_put_string(pkblob, blen);
495 packet_send();
496 packet_write_wait();
497 authctxt->postponed = 1;
a306f2dd 498 }
a306f2dd 499 }
67fa09f5 500 if (authenticated != 1)
501 auth_clear_options();
502done:
fa08c86b 503 debug2("userauth_pubkey: authenticated %d pkalg %s", authenticated, pkalg);
67fa09f5 504 if (key != NULL)
505 key_free(key);
a306f2dd 506 xfree(pkalg);
507 xfree(pkblob);
94ec8c6b 508#ifdef HAVE_CYGWIN
e9571a2c 509 if (check_nt_auth(0, authctxt->pw) == 0)
94ec8c6b 510 return(0);
511#endif
a306f2dd 512 return authenticated;
513}
514
396c147e 515static int
8002af61 516userauth_hostbased(Authctxt *authctxt)
517{
518 Buffer b;
67fa09f5 519 Key *key = NULL;
c66f9d0e 520 char *pkalg, *cuser, *chost, *service;
521 u_char *pkblob, *sig;
8002af61 522 u_int alen, blen, slen;
523 int pktype;
524 int authenticated = 0;
525
526 if (!authctxt->valid) {
527 debug2("userauth_hostbased: disabled because of invalid user");
528 return 0;
529 }
530 pkalg = packet_get_string(&alen);
531 pkblob = packet_get_string(&blen);
532 chost = packet_get_string(NULL);
533 cuser = packet_get_string(NULL);
534 sig = packet_get_string(&slen);
535
536 debug("userauth_hostbased: cuser %s chost %s pkalg %s slen %d",
537 cuser, chost, pkalg, slen);
538#ifdef DEBUG_PK
539 debug("signature:");
540 buffer_init(&b);
541 buffer_append(&b, sig, slen);
542 buffer_dump(&b);
543 buffer_free(&b);
544#endif
545 pktype = key_type_from_name(pkalg);
546 if (pktype == KEY_UNSPEC) {
547 /* this is perfectly legal */
548 log("userauth_hostbased: unsupported "
549 "public key algorithm: %s", pkalg);
550 goto done;
551 }
552 key = key_from_blob(pkblob, blen);
553 if (key == NULL) {
67fa09f5 554 error("userauth_hostbased: cannot decode key: %s", pkalg);
555 goto done;
556 }
557 if (key->type != pktype) {
558 error("userauth_hostbased: type mismatch for decoded key "
559 "(received %d, expected %d)", key->type, pktype);
8002af61 560 goto done;
561 }
8dddf799 562 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
563 authctxt->service;
8002af61 564 buffer_init(&b);
8dddf799 565 buffer_put_string(&b, session_id2, session_id2_len);
8002af61 566 /* reconstruct packet */
567 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
568 buffer_put_cstring(&b, authctxt->user);
8dddf799 569 buffer_put_cstring(&b, service);
8002af61 570 buffer_put_cstring(&b, "hostbased");
571 buffer_put_string(&b, pkalg, alen);
572 buffer_put_string(&b, pkblob, blen);
573 buffer_put_cstring(&b, chost);
574 buffer_put_cstring(&b, cuser);
575#ifdef DEBUG_PK
576 buffer_dump(&b);
577#endif
578 /* test for allowed key and correct signature */
1853d1ef 579 authenticated = 0;
580 if (PRIVSEP(hostbased_key_allowed(authctxt->pw, cuser, chost, key)) &&
581 PRIVSEP(key_verify(key, sig, slen, buffer_ptr(&b),
582 buffer_len(&b))) == 1)
63284fbb 583 authenticated = 1;
8002af61 584
585 buffer_clear(&b);
8002af61 586done:
587 debug2("userauth_hostbased: authenticated %d", authenticated);
67fa09f5 588 if (key != NULL)
589 key_free(key);
8002af61 590 xfree(pkalg);
591 xfree(pkblob);
592 xfree(cuser);
593 xfree(chost);
594 xfree(sig);
595 return authenticated;
596}
597
94ec8c6b 598/* get current user */
a306f2dd 599
600struct passwd*
601auth_get_user(void)
602{
94ec8c6b 603 return (x_authctxt != NULL && x_authctxt->valid) ? x_authctxt->pw : NULL;
a306f2dd 604}
605
94ec8c6b 606#define DELIM ","
607
ffb215be 608static char *
94ec8c6b 609authmethods_get(void)
a306f2dd 610{
94ec8c6b 611 Authmethod *method = NULL;
3469eac4 612 Buffer b;
94ec8c6b 613 char *list;
614
3469eac4 615 buffer_init(&b);
94ec8c6b 616 for (method = authmethods; method->name != NULL; method++) {
617 if (strcmp(method->name, "none") == 0)
618 continue;
619 if (method->enabled != NULL && *(method->enabled) != 0) {
3469eac4 620 if (buffer_len(&b) > 0)
621 buffer_append(&b, ",", 1);
622 buffer_append(&b, method->name, strlen(method->name));
a306f2dd 623 }
624 }
3469eac4 625 buffer_append(&b, "\0", 1);
626 list = xstrdup(buffer_ptr(&b));
627 buffer_free(&b);
94ec8c6b 628 return list;
629}
630
396c147e 631static Authmethod *
94ec8c6b 632authmethod_lookup(const char *name)
633{
634 Authmethod *method = NULL;
635 if (name != NULL)
636 for (method = authmethods; method->name != NULL; method++)
637 if (method->enabled != NULL &&
638 *(method->enabled) != 0 &&
639 strcmp(name, method->name) == 0)
640 return method;
641 debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
642 return NULL;
a306f2dd 643}
644
645/* return 1 if user allows given key */
396c147e 646static int
96a7b0cc 647user_key_allowed2(struct passwd *pw, Key *key, char *file)
a306f2dd 648{
96a7b0cc 649 char line[8192];
a306f2dd 650 int found_key = 0;
a306f2dd 651 FILE *f;
1e3b8b07 652 u_long linenum = 0;
a306f2dd 653 struct stat st;
654 Key *found;
306feb91 655 char *fp;
a306f2dd 656
94ec8c6b 657 if (pw == NULL)
658 return 0;
659
a306f2dd 660 /* Temporarily use the user's uid. */
63bd8c36 661 temporarily_use_uid(pw);
a306f2dd 662
c8445989 663 debug("trying public key file %s", file);
a306f2dd 664
665 /* Fail quietly if file does not exist */
666 if (stat(file, &st) < 0) {
667 /* Restore the privileged uid. */
668 restore_uid();
669 return 0;
670 }
671 /* Open the file containing the authorized keys. */
672 f = fopen(file, "r");
673 if (!f) {
674 /* Restore the privileged uid. */
675 restore_uid();
676 return 0;
677 }
c8445989 678 if (options.strict_modes &&
0c9664c2 679 secure_filename(f, file, pw, line, sizeof(line)) != 0) {
c8445989 680 fclose(f);
681 log("Authentication refused: %s", line);
682 restore_uid();
683 return 0;
a306f2dd 684 }
c8445989 685
a306f2dd 686 found_key = 0;
de273eef 687 found = key_new(key->type);
a306f2dd 688
689 while (fgets(line, sizeof(line), f)) {
38c295d6 690 char *cp, *options = NULL;
a306f2dd 691 linenum++;
692 /* Skip leading whitespace, empty and comment lines. */
693 for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
694 ;
695 if (!*cp || *cp == '\n' || *cp == '#')
696 continue;
38c295d6 697
ddcfed57 698 if (key_read(found, &cp) != 1) {
38c295d6 699 /* no key? check if there are options for this key */
700 int quoted = 0;
fa08c86b 701 debug2("user_key_allowed: check options: '%s'", cp);
38c295d6 702 options = cp;
703 for (; *cp && (quoted || (*cp != ' ' && *cp != '\t')); cp++) {
704 if (*cp == '\\' && cp[1] == '"')
705 cp++; /* Skip both */
706 else if (*cp == '"')
707 quoted = !quoted;
708 }
709 /* Skip remaining whitespace. */
710 for (; *cp == ' ' || *cp == '\t'; cp++)
711 ;
ddcfed57 712 if (key_read(found, &cp) != 1) {
fa08c86b 713 debug2("user_key_allowed: advance: '%s'", cp);
38c295d6 714 /* still no key? advance to next line*/
715 continue;
716 }
717 }
718 if (key_equal(found, key) &&
42f11eb2 719 auth_parse_options(pw, options, file, linenum) == 1) {
a306f2dd 720 found_key = 1;
1bdee08c 721 debug("matching key found: file %s, line %lu",
a306f2dd 722 file, linenum);
306feb91 723 fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
724 verbose("Found matching %s key: %s",
184eed6a 725 key_type(found), fp);
306feb91 726 xfree(fp);
a306f2dd 727 break;
728 }
729 }
730 restore_uid();
731 fclose(f);
732 key_free(found);
539af7f5 733 if (!found_key)
734 debug2("key not found");
a306f2dd 735 return found_key;
736}
8002af61 737
96a7b0cc 738/* check whether given key is in .ssh/authorized_keys* */
1853d1ef 739int
96a7b0cc 740user_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
8002af61 758/* return 1 if given hostkey is allowed */
1853d1ef 759int
57a5edd8 760hostbased_key_allowed(struct passwd *pw, const char *cuser, char *chost,
8002af61 761 Key *key)
762{
8002af61 763 const char *resolvedname, *ipaddr, *lookup;
17a3011c 764 HostStatus host_status;
765 int len;
8002af61 766
bf4c5edc 767 resolvedname = get_canonical_hostname(options.verify_reverse_mapping);
8002af61 768 ipaddr = get_remote_ipaddr();
769
f98c3421 770 debug2("userauth_hostbased: chost %s resolvedname %s ipaddr %s",
771 chost, resolvedname, ipaddr);
8002af61 772
773 if (options.hostbased_uses_name_from_packet_only) {
774 if (auth_rhosts2(pw, cuser, chost, chost) == 0)
775 return 0;
776 lookup = chost;
777 } else {
f98c3421 778 if (((len = strlen(chost)) > 0) && chost[len - 1] == '.') {
779 debug2("stripping trailing dot from chost %s", chost);
780 chost[len - 1] = '\0';
781 }
8002af61 782 if (strcasecmp(resolvedname, chost) != 0)
783 log("userauth_hostbased mismatch: "
784 "client sends %s, but we resolve %s to %s",
785 chost, ipaddr, resolvedname);
786 if (auth_rhosts2(pw, cuser, resolvedname, ipaddr) == 0)
787 return 0;
788 lookup = resolvedname;
789 }
790 debug2("userauth_hostbased: access allowed by auth_rhosts2");
791
d0c8ca5c 792 host_status = check_key_in_hostfiles(pw, key, lookup,
793 _PATH_SSH_SYSTEM_HOSTFILE,
73473230 794 options.ignore_user_known_hosts ? NULL : _PATH_SSH_USER_HOSTFILE);
d0c8ca5c 795
796 /* backward compat if no key has been found. */
797 if (host_status == HOST_NEW)
798 host_status = check_key_in_hostfiles(pw, key, lookup,
799 _PATH_SSH_SYSTEM_HOSTFILE2,
73473230 800 options.ignore_user_known_hosts ? NULL :
801 _PATH_SSH_USER_HOSTFILE2);
8002af61 802
8002af61 803 return (host_status == HOST_OK);
804}
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