1 /* $OpenBSD: auth2.c,v 1.160 2021/01/27 10:05:28 djm Exp $ */
2 /*
3 * Copyright (c) 2000 Markus Friedl. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26 #include "includes.h"
27
28 #include <sys/types.h>
29 #include <sys/stat.h>
30 #include <sys/uio.h>
31
32 #include <fcntl.h>
33 #include <limits.h>
34 #include <pwd.h>
35 #include <stdarg.h>
36 #include <string.h>
37 #include <unistd.h>
38 #include <time.h>
39
40 #include "stdlib.h"
41 #include "atomicio.h"
42 #include "xmalloc.h"
43 #include "ssh2.h"
44 #include "packet.h"
45 #include "log.h"
46 #include "sshbuf.h"
47 #include "misc.h"
48 #include "servconf.h"
49 #include "compat.h"
50 #include "sshkey.h"
51 #include "hostfile.h"
52 #include "auth.h"
53 #include "dispatch.h"
54 #include "pathnames.h"
55 #include "ssherr.h"
56 #ifdef GSSAPI
57 #include "ssh-gss.h"
58 #endif
59 #include "monitor_wrap.h"
60 #include "digest.h"
61
62 /* import */
63 extern ServerOptions options;
64 extern struct sshbuf *loginmsg;
65
66 /* methods */
67
68 extern Authmethod method_none;
69 extern Authmethod method_pubkey;
70 extern Authmethod method_passwd;
71 extern Authmethod method_kbdint;
72 extern Authmethod method_hostbased;
73 #ifdef GSSAPI
74 extern Authmethod method_gssapi;
75 #endif
76
77 Authmethod *authmethods[] = {
78 &method_none,
79 &method_pubkey,
80 #ifdef GSSAPI
81 &method_gssapi,
82 #endif
83 &method_passwd,
84 &method_kbdint,
85 &method_hostbased,
86 NULL
87 };
88
89 /* protocol */
90
91 static int input_service_request(int, u_int32_t, struct ssh *);
92 static int input_userauth_request(int, u_int32_t, struct ssh *);
93
94 /* helper */
95 static Authmethod *authmethod_lookup(Authctxt *, const char *);
96 static char *authmethods_get(Authctxt *authctxt);
97
98 #define MATCH_NONE 0 /* method or submethod mismatch */
99 #define MATCH_METHOD 1 /* method matches (no submethod specified) */
100 #define MATCH_BOTH 2 /* method and submethod match */
101 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */
102 static int list_starts_with(const char *, const char *, const char *);
103
104 char *
auth2_read_banner(void)105 auth2_read_banner(void)
106 {
107 struct stat st;
108 char *banner = NULL;
109 size_t len, n;
110 int fd;
111
112 if ((fd = open(options.banner, O_RDONLY)) == -1)
113 return (NULL);
114 if (fstat(fd, &st) == -1) {
115 close(fd);
116 return (NULL);
117 }
118 if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
119 close(fd);
120 return (NULL);
121 }
122
123 len = (size_t)st.st_size; /* truncate */
124 banner = xmalloc(len + 1);
125 n = atomicio(read, fd, banner, len);
126 close(fd);
127
128 if (n != len) {
129 free(banner);
130 return (NULL);
131 }
132 banner[n] = '\0';
133
134 return (banner);
135 }
136
137 static void
userauth_send_banner(struct ssh * ssh,const char * msg)138 userauth_send_banner(struct ssh *ssh, const char *msg)
139 {
140 int r;
141
142 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 ||
143 (r = sshpkt_put_cstring(ssh, msg)) != 0 ||
144 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */
145 (r = sshpkt_send(ssh)) != 0)
146 fatal_fr(r, "send packet");
147 debug("%s: sent", __func__);
148 }
149
150 static void
userauth_banner(struct ssh * ssh)151 userauth_banner(struct ssh *ssh)
152 {
153 char *banner = NULL;
154
155 if (options.banner == NULL)
156 return;
157
158 if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
159 goto done;
160 userauth_send_banner(ssh, banner);
161
162 done:
163 free(banner);
164 }
165
166 /*
167 * loop until authctxt->success == TRUE
168 */
169 void
do_authentication2(struct ssh * ssh)170 do_authentication2(struct ssh *ssh)
171 {
172 Authctxt *authctxt = ssh->authctxt;
173
174 ssh_dispatch_init(ssh, &dispatch_protocol_error);
175 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request);
176 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success);
177 ssh->authctxt = NULL;
178 }
179
180 /*ARGSUSED*/
181 static int
input_service_request(int type,u_int32_t seq,struct ssh * ssh)182 input_service_request(int type, u_int32_t seq, struct ssh *ssh)
183 {
184 Authctxt *authctxt = ssh->authctxt;
185 char *service = NULL;
186 int r, acceptit = 0;
187
188 if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
189 (r = sshpkt_get_end(ssh)) != 0)
190 goto out;
191
192 if (authctxt == NULL)
193 fatal("input_service_request: no authctxt");
194
195 if (strcmp(service, "ssh-userauth") == 0) {
196 if (!authctxt->success) {
197 acceptit = 1;
198 /* now we can handle user-auth requests */
199 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
200 &input_userauth_request);
201 }
202 }
203 /* XXX all other service requests are denied */
204
205 if (acceptit) {
206 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 ||
207 (r = sshpkt_put_cstring(ssh, service)) != 0 ||
208 (r = sshpkt_send(ssh)) != 0 ||
209 (r = ssh_packet_write_wait(ssh)) != 0)
210 goto out;
211 } else {
212 debug("bad service request %s", service);
213 ssh_packet_disconnect(ssh, "bad service request %s", service);
214 }
215 r = 0;
216 out:
217 free(service);
218 return r;
219 }
220
221 #define MIN_FAIL_DELAY_SECONDS 0.005
222 static double
user_specific_delay(const char * user)223 user_specific_delay(const char *user)
224 {
225 char b[512];
226 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512);
227 u_char *hash = xmalloc(len);
228 double delay;
229
230 (void)snprintf(b, sizeof b, "%llu%s",
231 (unsigned long long)options.timing_secret, user);
232 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0)
233 fatal_f("ssh_digest_memory");
234 /* 0-4.2 ms of delay */
235 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000;
236 freezero(hash, len);
237 debug3_f("user specific delay %0.3lfms", delay/1000);
238 return MIN_FAIL_DELAY_SECONDS + delay;
239 }
240
241 static void
ensure_minimum_time_since(double start,double seconds)242 ensure_minimum_time_since(double start, double seconds)
243 {
244 struct timespec ts;
245 double elapsed = monotime_double() - start, req = seconds, remain;
246
247 /* if we've already passed the requested time, scale up */
248 while ((remain = seconds - elapsed) < 0.0)
249 seconds *= 2;
250
251 ts.tv_sec = remain;
252 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;
253 debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)",
254 elapsed*1000, remain*1000, req*1000);
255 nanosleep(&ts, NULL);
256 }
257
258 /*ARGSUSED*/
259 static int
input_userauth_request(int type,u_int32_t seq,struct ssh * ssh)260 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
261 {
262 Authctxt *authctxt = ssh->authctxt;
263 Authmethod *m = NULL;
264 char *user = NULL, *service = NULL, *method = NULL, *style = NULL;
265 int r, authenticated = 0;
266 double tstart = monotime_double();
267
268 if (authctxt == NULL)
269 fatal("input_userauth_request: no authctxt");
270
271 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 ||
272 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
273 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0)
274 goto out;
275 debug("userauth-request for user %s service %s method %s", user, service, method);
276 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
277
278 if ((style = strchr(user, ':')) != NULL)
279 *style++ = 0;
280
281 if (authctxt->attempt++ == 0) {
282 /* setup auth context */
283 authctxt->pw = PRIVSEP(getpwnamallow(ssh, user));
284 authctxt->user = xstrdup(user);
285 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
286 authctxt->valid = 1;
287 debug2_f("setting up authctxt for %s", user);
288 } else {
289 /* Invalid user, fake password information */
290 authctxt->pw = fakepw();
291 #ifdef SSH_AUDIT_EVENTS
292 PRIVSEP(audit_event(ssh, SSH_INVALID_USER));
293 #endif
294 }
295 #ifdef USE_PAM
296 if (options.use_pam)
297 PRIVSEP(start_pam(ssh));
298 #endif
299 ssh_packet_set_log_preamble(ssh, "%suser %s",
300 authctxt->valid ? "authenticating " : "invalid ", user);
301 setproctitle("%s%s", authctxt->valid ? user : "unknown",
302 use_privsep ? " [net]" : "");
303 authctxt->service = xstrdup(service);
304 authctxt->style = style ? xstrdup(style) : NULL;
305 if (use_privsep)
306 mm_inform_authserv(service, style);
307 userauth_banner(ssh);
308 if (auth2_setup_methods_lists(authctxt) != 0)
309 ssh_packet_disconnect(ssh,
310 "no authentication methods enabled");
311 } else if (strcmp(user, authctxt->user) != 0 ||
312 strcmp(service, authctxt->service) != 0) {
313 ssh_packet_disconnect(ssh, "Change of username or service "
314 "not allowed: (%s,%s) -> (%s,%s)",
315 authctxt->user, authctxt->service, user, service);
316 }
317 /* reset state */
318 auth2_challenge_stop(ssh);
319
320 #ifdef GSSAPI
321 /* XXX move to auth2_gssapi_stop() */
322 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
323 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
324 #endif
325
326 auth2_authctxt_reset_info(authctxt);
327 authctxt->postponed = 0;
328 authctxt->server_caused_failure = 0;
329
330 /* try to authenticate user */
331 m = authmethod_lookup(authctxt, method);
332 if (m != NULL && authctxt->failures < options.max_authtries) {
333 debug2("input_userauth_request: try method %s", method);
334 authenticated = m->userauth(ssh);
335 }
336 if (!authctxt->authenticated)
337 ensure_minimum_time_since(tstart,
338 user_specific_delay(authctxt->user));
339 userauth_finish(ssh, authenticated, method, NULL);
340 r = 0;
341 out:
342 free(service);
343 free(user);
344 free(method);
345 return r;
346 }
347
348 void
userauth_finish(struct ssh * ssh,int authenticated,const char * method,const char * submethod)349 userauth_finish(struct ssh *ssh, int authenticated, const char *method,
350 const char *submethod)
351 {
352 Authctxt *authctxt = ssh->authctxt;
353 char *methods;
354 int r, partial = 0;
355
356 if (!authctxt->valid && authenticated)
357 fatal("INTERNAL ERROR: authenticated invalid user %s",
358 authctxt->user);
359 if (authenticated && authctxt->postponed)
360 fatal("INTERNAL ERROR: authenticated and postponed");
361
362 /* Special handling for root */
363 if (authenticated && authctxt->pw->pw_uid == 0 &&
364 !auth_root_allowed(ssh, method)) {
365 authenticated = 0;
366 #ifdef SSH_AUDIT_EVENTS
367 PRIVSEP(audit_event(ssh, SSH_LOGIN_ROOT_DENIED));
368 #endif
369 }
370
371 if (authenticated && options.num_auth_methods != 0) {
372 if (!auth2_update_methods_lists(authctxt, method, submethod)) {
373 authenticated = 0;
374 partial = 1;
375 }
376 }
377
378 /* Log before sending the reply */
379 auth_log(ssh, authenticated, partial, method, submethod);
380
381 /* Update information exposed to session */
382 if (authenticated || partial)
383 auth2_update_session_info(authctxt, method, submethod);
384
385 if (authctxt->postponed)
386 return;
387
388 #ifdef USE_PAM
389 if (options.use_pam && authenticated) {
390 int r, success = PRIVSEP(do_pam_account());
391
392 /* If PAM returned a message, send it to the user. */
393 if (sshbuf_len(loginmsg) > 0) {
394 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0)
395 fatal("%s: buffer error: %s",
396 __func__, ssh_err(r));
397 userauth_send_banner(ssh, sshbuf_ptr(loginmsg));
398 if ((r = ssh_packet_write_wait(ssh)) != 0) {
399 sshpkt_fatal(ssh, r,
400 "%s: send PAM banner", __func__);
401 }
402 }
403 if (!success) {
404 fatal("Access denied for user %s by PAM account "
405 "configuration", authctxt->user);
406 }
407 }
408 #endif
409
410 if (authenticated == 1) {
411 /* turn off userauth */
412 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
413 &dispatch_protocol_ignore);
414 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 ||
415 (r = sshpkt_send(ssh)) != 0 ||
416 (r = ssh_packet_write_wait(ssh)) != 0)
417 fatal_fr(r, "send success packet");
418 /* now we can break out */
419 authctxt->success = 1;
420 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
421 } else {
422 /* Allow initial try of "none" auth without failure penalty */
423 if (!partial && !authctxt->server_caused_failure &&
424 (authctxt->attempt > 1 || strcmp(method, "none") != 0))
425 authctxt->failures++;
426 if (authctxt->failures >= options.max_authtries) {
427 #ifdef SSH_AUDIT_EVENTS
428 PRIVSEP(audit_event(ssh, SSH_LOGIN_EXCEED_MAXTRIES));
429 #endif
430 auth_maxtries_exceeded(ssh);
431 }
432 methods = authmethods_get(authctxt);
433 debug3_f("failure partial=%d next methods=\"%s\"",
434 partial, methods);
435 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 ||
436 (r = sshpkt_put_cstring(ssh, methods)) != 0 ||
437 (r = sshpkt_put_u8(ssh, partial)) != 0 ||
438 (r = sshpkt_send(ssh)) != 0 ||
439 (r = ssh_packet_write_wait(ssh)) != 0)
440 fatal_fr(r, "send failure packet");
441 free(methods);
442 }
443 }
444
445 /*
446 * Checks whether method is allowed by at least one AuthenticationMethods
447 * methods list. Returns 1 if allowed, or no methods lists configured.
448 * 0 otherwise.
449 */
450 int
auth2_method_allowed(Authctxt * authctxt,const char * method,const char * submethod)451 auth2_method_allowed(Authctxt *authctxt, const char *method,
452 const char *submethod)
453 {
454 u_int i;
455
456 /*
457 * NB. authctxt->num_auth_methods might be zero as a result of
458 * auth2_setup_methods_lists(), so check the configuration.
459 */
460 if (options.num_auth_methods == 0)
461 return 1;
462 for (i = 0; i < authctxt->num_auth_methods; i++) {
463 if (list_starts_with(authctxt->auth_methods[i], method,
464 submethod) != MATCH_NONE)
465 return 1;
466 }
467 return 0;
468 }
469
470 static char *
authmethods_get(Authctxt * authctxt)471 authmethods_get(Authctxt *authctxt)
472 {
473 struct sshbuf *b;
474 char *list;
475 int i, r;
476
477 if ((b = sshbuf_new()) == NULL)
478 fatal_f("sshbuf_new failed");
479 for (i = 0; authmethods[i] != NULL; i++) {
480 if (strcmp(authmethods[i]->name, "none") == 0)
481 continue;
482 if (authmethods[i]->enabled == NULL ||
483 *(authmethods[i]->enabled) == 0)
484 continue;
485 if (!auth2_method_allowed(authctxt, authmethods[i]->name,
486 NULL))
487 continue;
488 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "",
489 authmethods[i]->name)) != 0)
490 fatal_fr(r, "buffer error");
491 }
492 if ((list = sshbuf_dup_string(b)) == NULL)
493 fatal_f("sshbuf_dup_string failed");
494 sshbuf_free(b);
495 return list;
496 }
497
498 static Authmethod *
authmethod_lookup(Authctxt * authctxt,const char * name)499 authmethod_lookup(Authctxt *authctxt, const char *name)
500 {
501 int i;
502
503 if (name != NULL)
504 for (i = 0; authmethods[i] != NULL; i++)
505 if (authmethods[i]->enabled != NULL &&
506 *(authmethods[i]->enabled) != 0 &&
507 strcmp(name, authmethods[i]->name) == 0 &&
508 auth2_method_allowed(authctxt,
509 authmethods[i]->name, NULL))
510 return authmethods[i];
511 debug2("Unrecognized authentication method name: %s",
512 name ? name : "NULL");
513 return NULL;
514 }
515
516 /*
517 * Check a comma-separated list of methods for validity. Is need_enable is
518 * non-zero, then also require that the methods are enabled.
519 * Returns 0 on success or -1 if the methods list is invalid.
520 */
521 int
auth2_methods_valid(const char * _methods,int need_enable)522 auth2_methods_valid(const char *_methods, int need_enable)
523 {
524 char *methods, *omethods, *method, *p;
525 u_int i, found;
526 int ret = -1;
527
528 if (*_methods == '\0') {
529 error("empty authentication method list");
530 return -1;
531 }
532 omethods = methods = xstrdup(_methods);
533 while ((method = strsep(&methods, ",")) != NULL) {
534 for (found = i = 0; !found && authmethods[i] != NULL; i++) {
535 if ((p = strchr(method, ':')) != NULL)
536 *p = '\0';
537 if (strcmp(method, authmethods[i]->name) != 0)
538 continue;
539 if (need_enable) {
540 if (authmethods[i]->enabled == NULL ||
541 *(authmethods[i]->enabled) == 0) {
542 error("Disabled method \"%s\" in "
543 "AuthenticationMethods list \"%s\"",
544 method, _methods);
545 goto out;
546 }
547 }
548 found = 1;
549 break;
550 }
551 if (!found) {
552 error("Unknown authentication method \"%s\" in list",
553 method);
554 goto out;
555 }
556 }
557 ret = 0;
558 out:
559 free(omethods);
560 return ret;
561 }
562
563 /*
564 * Prune the AuthenticationMethods supplied in the configuration, removing
565 * any methods lists that include disabled methods. Note that this might
566 * leave authctxt->num_auth_methods == 0, even when multiple required auth
567 * has been requested. For this reason, all tests for whether multiple is
568 * enabled should consult options.num_auth_methods directly.
569 */
570 int
auth2_setup_methods_lists(Authctxt * authctxt)571 auth2_setup_methods_lists(Authctxt *authctxt)
572 {
573 u_int i;
574
575 /* First, normalise away the "any" pseudo-method */
576 if (options.num_auth_methods == 1 &&
577 strcmp(options.auth_methods[0], "any") == 0) {
578 free(options.auth_methods[0]);
579 options.auth_methods[0] = NULL;
580 options.num_auth_methods = 0;
581 }
582
583 if (options.num_auth_methods == 0)
584 return 0;
585 debug3_f("checking methods");
586 authctxt->auth_methods = xcalloc(options.num_auth_methods,
587 sizeof(*authctxt->auth_methods));
588 authctxt->num_auth_methods = 0;
589 for (i = 0; i < options.num_auth_methods; i++) {
590 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
591 logit("Authentication methods list \"%s\" contains "
592 "disabled method, skipping",
593 options.auth_methods[i]);
594 continue;
595 }
596 debug("authentication methods list %d: %s",
597 authctxt->num_auth_methods, options.auth_methods[i]);
598 authctxt->auth_methods[authctxt->num_auth_methods++] =
599 xstrdup(options.auth_methods[i]);
600 }
601 if (authctxt->num_auth_methods == 0) {
602 error("No AuthenticationMethods left after eliminating "
603 "disabled methods");
604 return -1;
605 }
606 return 0;
607 }
608
609 static int
list_starts_with(const char * methods,const char * method,const char * submethod)610 list_starts_with(const char *methods, const char *method,
611 const char *submethod)
612 {
613 size_t l = strlen(method);
614 int match;
615 const char *p;
616
617 if (strncmp(methods, method, l) != 0)
618 return MATCH_NONE;
619 p = methods + l;
620 match = MATCH_METHOD;
621 if (*p == ':') {
622 if (!submethod)
623 return MATCH_PARTIAL;
624 l = strlen(submethod);
625 p += 1;
626 if (strncmp(submethod, p, l))
627 return MATCH_NONE;
628 p += l;
629 match = MATCH_BOTH;
630 }
631 if (*p != ',' && *p != '\0')
632 return MATCH_NONE;
633 return match;
634 }
635
636 /*
637 * Remove method from the start of a comma-separated list of methods.
638 * Returns 0 if the list of methods did not start with that method or 1
639 * if it did.
640 */
641 static int
remove_method(char ** methods,const char * method,const char * submethod)642 remove_method(char **methods, const char *method, const char *submethod)
643 {
644 char *omethods = *methods, *p;
645 size_t l = strlen(method);
646 int match;
647
648 match = list_starts_with(omethods, method, submethod);
649 if (match != MATCH_METHOD && match != MATCH_BOTH)
650 return 0;
651 p = omethods + l;
652 if (submethod && match == MATCH_BOTH)
653 p += 1 + strlen(submethod); /* include colon */
654 if (*p == ',')
655 p++;
656 *methods = xstrdup(p);
657 free(omethods);
658 return 1;
659 }
660
661 /*
662 * Called after successful authentication. Will remove the successful method
663 * from the start of each list in which it occurs. If it was the last method
664 * in any list, then authentication is deemed successful.
665 * Returns 1 if the method completed any authentication list or 0 otherwise.
666 */
667 int
auth2_update_methods_lists(Authctxt * authctxt,const char * method,const char * submethod)668 auth2_update_methods_lists(Authctxt *authctxt, const char *method,
669 const char *submethod)
670 {
671 u_int i, found = 0;
672
673 debug3_f("updating methods list after \"%s\"", method);
674 for (i = 0; i < authctxt->num_auth_methods; i++) {
675 if (!remove_method(&(authctxt->auth_methods[i]), method,
676 submethod))
677 continue;
678 found = 1;
679 if (*authctxt->auth_methods[i] == '\0') {
680 debug2("authentication methods list %d complete", i);
681 return 1;
682 }
683 debug3("authentication methods list %d remaining: \"%s\"",
684 i, authctxt->auth_methods[i]);
685 }
686 /* This should not happen, but would be bad if it did */
687 if (!found)
688 fatal_f("method not in AuthenticationMethods");
689 return 0;
690 }
691
692 /* Reset method-specific information */
auth2_authctxt_reset_info(Authctxt * authctxt)693 void auth2_authctxt_reset_info(Authctxt *authctxt)
694 {
695 sshkey_free(authctxt->auth_method_key);
696 free(authctxt->auth_method_info);
697 authctxt->auth_method_key = NULL;
698 authctxt->auth_method_info = NULL;
699 }
700
701 /* Record auth method-specific information for logs */
702 void
auth2_record_info(Authctxt * authctxt,const char * fmt,...)703 auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
704 {
705 va_list ap;
706 int i;
707
708 free(authctxt->auth_method_info);
709 authctxt->auth_method_info = NULL;
710
711 va_start(ap, fmt);
712 i = vasprintf(&authctxt->auth_method_info, fmt, ap);
713 va_end(ap);
714
715 if (i == -1)
716 fatal_f("vasprintf failed");
717 }
718
719 /*
720 * Records a public key used in authentication. This is used for logging
721 * and to ensure that the same key is not subsequently accepted again for
722 * multiple authentication.
723 */
724 void
auth2_record_key(Authctxt * authctxt,int authenticated,const struct sshkey * key)725 auth2_record_key(Authctxt *authctxt, int authenticated,
726 const struct sshkey *key)
727 {
728 struct sshkey **tmp, *dup;
729 int r;
730
731 if ((r = sshkey_from_private(key, &dup)) != 0)
732 fatal_fr(r, "copy key");
733 sshkey_free(authctxt->auth_method_key);
734 authctxt->auth_method_key = dup;
735
736 if (!authenticated)
737 return;
738
739 /* If authenticated, make sure we don't accept this key again */
740 if ((r = sshkey_from_private(key, &dup)) != 0)
741 fatal_fr(r, "copy key");
742 if (authctxt->nprev_keys >= INT_MAX ||
743 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
744 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
745 fatal_f("reallocarray failed");
746 authctxt->prev_keys = tmp;
747 authctxt->prev_keys[authctxt->nprev_keys] = dup;
748 authctxt->nprev_keys++;
749
750 }
751
752 /* Checks whether a key has already been previously used for authentication */
753 int
auth2_key_already_used(Authctxt * authctxt,const struct sshkey * key)754 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
755 {
756 u_int i;
757 char *fp;
758
759 for (i = 0; i < authctxt->nprev_keys; i++) {
760 if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
761 fp = sshkey_fingerprint(authctxt->prev_keys[i],
762 options.fingerprint_hash, SSH_FP_DEFAULT);
763 debug3_f("key already used: %s %s",
764 sshkey_type(authctxt->prev_keys[i]),
765 fp == NULL ? "UNKNOWN" : fp);
766 free(fp);
767 return 1;
768 }
769 }
770 return 0;
771 }
772
773 /*
774 * Updates authctxt->session_info with details of authentication. Should be
775 * whenever an authentication method succeeds.
776 */
777 void
auth2_update_session_info(Authctxt * authctxt,const char * method,const char * submethod)778 auth2_update_session_info(Authctxt *authctxt, const char *method,
779 const char *submethod)
780 {
781 int r;
782
783 if (authctxt->session_info == NULL) {
784 if ((authctxt->session_info = sshbuf_new()) == NULL)
785 fatal_f("sshbuf_new");
786 }
787
788 /* Append method[/submethod] */
789 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
790 method, submethod == NULL ? "" : "/",
791 submethod == NULL ? "" : submethod)) != 0)
792 fatal_fr(r, "append method");
793
794 /* Append key if present */
795 if (authctxt->auth_method_key != NULL) {
796 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
797 (r = sshkey_format_text(authctxt->auth_method_key,
798 authctxt->session_info)) != 0)
799 fatal_fr(r, "append key");
800 }
801
802 if (authctxt->auth_method_info != NULL) {
803 /* Ensure no ambiguity here */
804 if (strchr(authctxt->auth_method_info, '\n') != NULL)
805 fatal_f("auth_method_info contains \\n");
806 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
807 (r = sshbuf_putf(authctxt->session_info, "%s",
808 authctxt->auth_method_info)) != 0) {
809 fatal_fr(r, "append method info");
810 }
811 }
812 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
813 fatal_fr(r, "append");
814 }
815
816