1 /* $OpenBSD: auth2.c,v 1.158 2020/03/06 18:16:21 markus 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 u_char *session_id2;
65 extern u_int session_id2_len;
66 extern struct sshbuf *loginmsg;
67
68 /* methods */
69
70 extern Authmethod method_none;
71 extern Authmethod method_pubkey;
72 extern Authmethod method_passwd;
73 extern Authmethod method_kbdint;
74 extern Authmethod method_hostbased;
75 #ifdef GSSAPI
76 extern Authmethod method_gssapi;
77 #endif
78
79 Authmethod *authmethods[] = {
80 &method_none,
81 &method_pubkey,
82 #ifdef GSSAPI
83 &method_gssapi,
84 #endif
85 &method_passwd,
86 &method_kbdint,
87 &method_hostbased,
88 NULL
89 };
90
91 /* protocol */
92
93 static int input_service_request(int, u_int32_t, struct ssh *);
94 static int input_userauth_request(int, u_int32_t, struct ssh *);
95
96 /* helper */
97 static Authmethod *authmethod_lookup(Authctxt *, const char *);
98 static char *authmethods_get(Authctxt *authctxt);
99
100 #define MATCH_NONE 0 /* method or submethod mismatch */
101 #define MATCH_METHOD 1 /* method matches (no submethod specified) */
102 #define MATCH_BOTH 2 /* method and submethod match */
103 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */
104 static int list_starts_with(const char *, const char *, const char *);
105
106 char *
auth2_read_banner(void)107 auth2_read_banner(void)
108 {
109 struct stat st;
110 char *banner = NULL;
111 size_t len, n;
112 int fd;
113
114 if ((fd = open(options.banner, O_RDONLY)) == -1)
115 return (NULL);
116 if (fstat(fd, &st) == -1) {
117 close(fd);
118 return (NULL);
119 }
120 if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
121 close(fd);
122 return (NULL);
123 }
124
125 len = (size_t)st.st_size; /* truncate */
126 banner = xmalloc(len + 1);
127 n = atomicio(read, fd, banner, len);
128 close(fd);
129
130 if (n != len) {
131 free(banner);
132 return (NULL);
133 }
134 banner[n] = '\0';
135
136 return (banner);
137 }
138
139 static void
userauth_send_banner(struct ssh * ssh,const char * msg)140 userauth_send_banner(struct ssh *ssh, const char *msg)
141 {
142 int r;
143
144 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 ||
145 (r = sshpkt_put_cstring(ssh, msg)) != 0 ||
146 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */
147 (r = sshpkt_send(ssh)) != 0)
148 fatal("%s: %s", __func__, ssh_err(r));
149 debug("%s: sent", __func__);
150 }
151
152 static void
userauth_banner(struct ssh * ssh)153 userauth_banner(struct ssh *ssh)
154 {
155 char *banner = NULL;
156
157 if (options.banner == NULL)
158 return;
159
160 if ((banner = PRIVSEP(auth2_read_banner())) == NULL)
161 goto done;
162 userauth_send_banner(ssh, banner);
163
164 done:
165 free(banner);
166 }
167
168 /*
169 * loop until authctxt->success == TRUE
170 */
171 void
do_authentication2(struct ssh * ssh)172 do_authentication2(struct ssh *ssh)
173 {
174 Authctxt *authctxt = ssh->authctxt;
175
176 ssh_dispatch_init(ssh, &dispatch_protocol_error);
177 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request);
178 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success);
179 ssh->authctxt = NULL;
180 }
181
182 /*ARGSUSED*/
183 static int
input_service_request(int type,u_int32_t seq,struct ssh * ssh)184 input_service_request(int type, u_int32_t seq, struct ssh *ssh)
185 {
186 Authctxt *authctxt = ssh->authctxt;
187 char *service = NULL;
188 int r, acceptit = 0;
189
190 if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
191 (r = sshpkt_get_end(ssh)) != 0)
192 goto out;
193
194 if (authctxt == NULL)
195 fatal("input_service_request: no authctxt");
196
197 if (strcmp(service, "ssh-userauth") == 0) {
198 if (!authctxt->success) {
199 acceptit = 1;
200 /* now we can handle user-auth requests */
201 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
202 &input_userauth_request);
203 }
204 }
205 /* XXX all other service requests are denied */
206
207 if (acceptit) {
208 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 ||
209 (r = sshpkt_put_cstring(ssh, service)) != 0 ||
210 (r = sshpkt_send(ssh)) != 0 ||
211 (r = ssh_packet_write_wait(ssh)) != 0)
212 goto out;
213 } else {
214 debug("bad service request %s", service);
215 ssh_packet_disconnect(ssh, "bad service request %s", service);
216 }
217 r = 0;
218 out:
219 free(service);
220 return r;
221 }
222
223 #define MIN_FAIL_DELAY_SECONDS 0.005
224 static double
user_specific_delay(const char * user)225 user_specific_delay(const char *user)
226 {
227 char b[512];
228 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512);
229 u_char *hash = xmalloc(len);
230 double delay;
231
232 (void)snprintf(b, sizeof b, "%llu%s",
233 (unsigned long long)options.timing_secret, user);
234 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0)
235 fatal("%s: ssh_digest_memory", __func__);
236 /* 0-4.2 ms of delay */
237 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000;
238 freezero(hash, len);
239 debug3("%s: user specific delay %0.3lfms", __func__, delay/1000);
240 return MIN_FAIL_DELAY_SECONDS + delay;
241 }
242
243 static void
ensure_minimum_time_since(double start,double seconds)244 ensure_minimum_time_since(double start, double seconds)
245 {
246 struct timespec ts;
247 double elapsed = monotime_double() - start, req = seconds, remain;
248
249 /* if we've already passed the requested time, scale up */
250 while ((remain = seconds - elapsed) < 0.0)
251 seconds *= 2;
252
253 ts.tv_sec = remain;
254 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;
255 debug3("%s: elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)",
256 __func__, elapsed*1000, remain*1000, req*1000);
257 nanosleep(&ts, NULL);
258 }
259
260 /*ARGSUSED*/
261 static int
input_userauth_request(int type,u_int32_t seq,struct ssh * ssh)262 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
263 {
264 Authctxt *authctxt = ssh->authctxt;
265 Authmethod *m = NULL;
266 char *user = NULL, *service = NULL, *method = NULL, *style = NULL;
267 int r, authenticated = 0;
268 double tstart = monotime_double();
269
270 if (authctxt == NULL)
271 fatal("input_userauth_request: no authctxt");
272
273 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 ||
274 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
275 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0)
276 goto out;
277 debug("userauth-request for user %s service %s method %s", user, service, method);
278 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
279
280 if ((style = strchr(user, ':')) != NULL)
281 *style++ = 0;
282
283 if (authctxt->attempt++ == 0) {
284 /* setup auth context */
285 authctxt->pw = PRIVSEP(getpwnamallow(ssh, user));
286 authctxt->user = xstrdup(user);
287 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
288 authctxt->valid = 1;
289 debug2("%s: setting up authctxt for %s",
290 __func__, user);
291 } else {
292 /* Invalid user, fake password information */
293 authctxt->pw = fakepw();
294 #ifdef SSH_AUDIT_EVENTS
295 PRIVSEP(audit_event(ssh, SSH_INVALID_USER));
296 #endif
297 }
298 #ifdef USE_PAM
299 if (options.use_pam)
300 PRIVSEP(start_pam(ssh));
301 #endif
302 ssh_packet_set_log_preamble(ssh, "%suser %s",
303 authctxt->valid ? "authenticating " : "invalid ", user);
304 setproctitle("%s%s", authctxt->valid ? user : "unknown",
305 use_privsep ? " [net]" : "");
306 authctxt->service = xstrdup(service);
307 authctxt->style = style ? xstrdup(style) : NULL;
308 if (use_privsep)
309 mm_inform_authserv(service, style);
310 userauth_banner(ssh);
311 if (auth2_setup_methods_lists(authctxt) != 0)
312 ssh_packet_disconnect(ssh,
313 "no authentication methods enabled");
314 } else if (strcmp(user, authctxt->user) != 0 ||
315 strcmp(service, authctxt->service) != 0) {
316 ssh_packet_disconnect(ssh, "Change of username or service "
317 "not allowed: (%s,%s) -> (%s,%s)",
318 authctxt->user, authctxt->service, user, service);
319 }
320 /* reset state */
321 auth2_challenge_stop(ssh);
322
323 #ifdef GSSAPI
324 /* XXX move to auth2_gssapi_stop() */
325 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
326 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
327 #endif
328
329 auth2_authctxt_reset_info(authctxt);
330 authctxt->postponed = 0;
331 authctxt->server_caused_failure = 0;
332
333 /* try to authenticate user */
334 m = authmethod_lookup(authctxt, method);
335 if (m != NULL && authctxt->failures < options.max_authtries) {
336 debug2("input_userauth_request: try method %s", method);
337 authenticated = m->userauth(ssh);
338 }
339 if (!authctxt->authenticated)
340 ensure_minimum_time_since(tstart,
341 user_specific_delay(authctxt->user));
342 userauth_finish(ssh, authenticated, method, NULL);
343 r = 0;
344 out:
345 free(service);
346 free(user);
347 free(method);
348 return r;
349 }
350
351 void
userauth_finish(struct ssh * ssh,int authenticated,const char * method,const char * submethod)352 userauth_finish(struct ssh *ssh, int authenticated, const char *method,
353 const char *submethod)
354 {
355 Authctxt *authctxt = ssh->authctxt;
356 char *methods;
357 int r, partial = 0;
358
359 if (!authctxt->valid && authenticated)
360 fatal("INTERNAL ERROR: authenticated invalid user %s",
361 authctxt->user);
362 if (authenticated && authctxt->postponed)
363 fatal("INTERNAL ERROR: authenticated and postponed");
364
365 /* Special handling for root */
366 if (authenticated && authctxt->pw->pw_uid == 0 &&
367 !auth_root_allowed(ssh, method)) {
368 authenticated = 0;
369 #ifdef SSH_AUDIT_EVENTS
370 PRIVSEP(audit_event(ssh, SSH_LOGIN_ROOT_DENIED));
371 #endif
372 }
373
374 if (authenticated && options.num_auth_methods != 0) {
375 if (!auth2_update_methods_lists(authctxt, method, submethod)) {
376 authenticated = 0;
377 partial = 1;
378 }
379 }
380
381 /* Log before sending the reply */
382 auth_log(ssh, authenticated, partial, method, submethod);
383
384 /* Update information exposed to session */
385 if (authenticated || partial)
386 auth2_update_session_info(authctxt, method, submethod);
387
388 if (authctxt->postponed)
389 return;
390
391 #ifdef USE_PAM
392 if (options.use_pam && authenticated) {
393 int r;
394
395 if (!PRIVSEP(do_pam_account())) {
396 /* if PAM returned a message, send it to the user */
397 if (sshbuf_len(loginmsg) > 0) {
398 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0)
399 fatal("%s: buffer error: %s",
400 __func__, ssh_err(r));
401 userauth_send_banner(ssh, sshbuf_ptr(loginmsg));
402 if ((r = ssh_packet_write_wait(ssh)) != 0) {
403 sshpkt_fatal(ssh, r,
404 "%s: send PAM banner", __func__);
405 }
406 }
407 fatal("Access denied for user %s by PAM account "
408 "configuration", authctxt->user);
409 }
410 }
411 #endif
412
413 if (authenticated == 1) {
414 /* turn off userauth */
415 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
416 &dispatch_protocol_ignore);
417 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 ||
418 (r = sshpkt_send(ssh)) != 0 ||
419 (r = ssh_packet_write_wait(ssh)) != 0)
420 fatal("%s: %s", __func__, ssh_err(r));
421 /* now we can break out */
422 authctxt->success = 1;
423 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
424 } else {
425 /* Allow initial try of "none" auth without failure penalty */
426 if (!partial && !authctxt->server_caused_failure &&
427 (authctxt->attempt > 1 || strcmp(method, "none") != 0))
428 authctxt->failures++;
429 if (authctxt->failures >= options.max_authtries) {
430 #ifdef SSH_AUDIT_EVENTS
431 PRIVSEP(audit_event(ssh, SSH_LOGIN_EXCEED_MAXTRIES));
432 #endif
433 auth_maxtries_exceeded(ssh);
434 }
435 methods = authmethods_get(authctxt);
436 debug3("%s: failure partial=%d next methods=\"%s\"", __func__,
437 partial, methods);
438 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 ||
439 (r = sshpkt_put_cstring(ssh, methods)) != 0 ||
440 (r = sshpkt_put_u8(ssh, partial)) != 0 ||
441 (r = sshpkt_send(ssh)) != 0 ||
442 (r = ssh_packet_write_wait(ssh)) != 0)
443 fatal("%s: %s", __func__, ssh_err(r));
444 free(methods);
445 }
446 }
447
448 /*
449 * Checks whether method is allowed by at least one AuthenticationMethods
450 * methods list. Returns 1 if allowed, or no methods lists configured.
451 * 0 otherwise.
452 */
453 int
auth2_method_allowed(Authctxt * authctxt,const char * method,const char * submethod)454 auth2_method_allowed(Authctxt *authctxt, const char *method,
455 const char *submethod)
456 {
457 u_int i;
458
459 /*
460 * NB. authctxt->num_auth_methods might be zero as a result of
461 * auth2_setup_methods_lists(), so check the configuration.
462 */
463 if (options.num_auth_methods == 0)
464 return 1;
465 for (i = 0; i < authctxt->num_auth_methods; i++) {
466 if (list_starts_with(authctxt->auth_methods[i], method,
467 submethod) != MATCH_NONE)
468 return 1;
469 }
470 return 0;
471 }
472
473 static char *
authmethods_get(Authctxt * authctxt)474 authmethods_get(Authctxt *authctxt)
475 {
476 struct sshbuf *b;
477 char *list;
478 int i, r;
479
480 if ((b = sshbuf_new()) == NULL)
481 fatal("%s: sshbuf_new failed", __func__);
482 for (i = 0; authmethods[i] != NULL; i++) {
483 if (strcmp(authmethods[i]->name, "none") == 0)
484 continue;
485 if (authmethods[i]->enabled == NULL ||
486 *(authmethods[i]->enabled) == 0)
487 continue;
488 if (!auth2_method_allowed(authctxt, authmethods[i]->name,
489 NULL))
490 continue;
491 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "",
492 authmethods[i]->name)) != 0)
493 fatal("%s: buffer error: %s", __func__, ssh_err(r));
494 }
495 if ((list = sshbuf_dup_string(b)) == NULL)
496 fatal("%s: sshbuf_dup_string failed", __func__);
497 sshbuf_free(b);
498 return list;
499 }
500
501 static Authmethod *
authmethod_lookup(Authctxt * authctxt,const char * name)502 authmethod_lookup(Authctxt *authctxt, const char *name)
503 {
504 int i;
505
506 if (name != NULL)
507 for (i = 0; authmethods[i] != NULL; i++)
508 if (authmethods[i]->enabled != NULL &&
509 *(authmethods[i]->enabled) != 0 &&
510 strcmp(name, authmethods[i]->name) == 0 &&
511 auth2_method_allowed(authctxt,
512 authmethods[i]->name, NULL))
513 return authmethods[i];
514 debug2("Unrecognized authentication method name: %s",
515 name ? name : "NULL");
516 return NULL;
517 }
518
519 /*
520 * Check a comma-separated list of methods for validity. Is need_enable is
521 * non-zero, then also require that the methods are enabled.
522 * Returns 0 on success or -1 if the methods list is invalid.
523 */
524 int
auth2_methods_valid(const char * _methods,int need_enable)525 auth2_methods_valid(const char *_methods, int need_enable)
526 {
527 char *methods, *omethods, *method, *p;
528 u_int i, found;
529 int ret = -1;
530
531 if (*_methods == '\0') {
532 error("empty authentication method list");
533 return -1;
534 }
535 omethods = methods = xstrdup(_methods);
536 while ((method = strsep(&methods, ",")) != NULL) {
537 for (found = i = 0; !found && authmethods[i] != NULL; i++) {
538 if ((p = strchr(method, ':')) != NULL)
539 *p = '\0';
540 if (strcmp(method, authmethods[i]->name) != 0)
541 continue;
542 if (need_enable) {
543 if (authmethods[i]->enabled == NULL ||
544 *(authmethods[i]->enabled) == 0) {
545 error("Disabled method \"%s\" in "
546 "AuthenticationMethods list \"%s\"",
547 method, _methods);
548 goto out;
549 }
550 }
551 found = 1;
552 break;
553 }
554 if (!found) {
555 error("Unknown authentication method \"%s\" in list",
556 method);
557 goto out;
558 }
559 }
560 ret = 0;
561 out:
562 free(omethods);
563 return ret;
564 }
565
566 /*
567 * Prune the AuthenticationMethods supplied in the configuration, removing
568 * any methods lists that include disabled methods. Note that this might
569 * leave authctxt->num_auth_methods == 0, even when multiple required auth
570 * has been requested. For this reason, all tests for whether multiple is
571 * enabled should consult options.num_auth_methods directly.
572 */
573 int
auth2_setup_methods_lists(Authctxt * authctxt)574 auth2_setup_methods_lists(Authctxt *authctxt)
575 {
576 u_int i;
577
578 /* First, normalise away the "any" pseudo-method */
579 if (options.num_auth_methods == 1 &&
580 strcmp(options.auth_methods[0], "any") == 0) {
581 free(options.auth_methods[0]);
582 options.auth_methods[0] = NULL;
583 options.num_auth_methods = 0;
584 }
585
586 if (options.num_auth_methods == 0)
587 return 0;
588 debug3("%s: checking methods", __func__);
589 authctxt->auth_methods = xcalloc(options.num_auth_methods,
590 sizeof(*authctxt->auth_methods));
591 authctxt->num_auth_methods = 0;
592 for (i = 0; i < options.num_auth_methods; i++) {
593 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
594 logit("Authentication methods list \"%s\" contains "
595 "disabled method, skipping",
596 options.auth_methods[i]);
597 continue;
598 }
599 debug("authentication methods list %d: %s",
600 authctxt->num_auth_methods, options.auth_methods[i]);
601 authctxt->auth_methods[authctxt->num_auth_methods++] =
602 xstrdup(options.auth_methods[i]);
603 }
604 if (authctxt->num_auth_methods == 0) {
605 error("No AuthenticationMethods left after eliminating "
606 "disabled methods");
607 return -1;
608 }
609 return 0;
610 }
611
612 static int
list_starts_with(const char * methods,const char * method,const char * submethod)613 list_starts_with(const char *methods, const char *method,
614 const char *submethod)
615 {
616 size_t l = strlen(method);
617 int match;
618 const char *p;
619
620 if (strncmp(methods, method, l) != 0)
621 return MATCH_NONE;
622 p = methods + l;
623 match = MATCH_METHOD;
624 if (*p == ':') {
625 if (!submethod)
626 return MATCH_PARTIAL;
627 l = strlen(submethod);
628 p += 1;
629 if (strncmp(submethod, p, l))
630 return MATCH_NONE;
631 p += l;
632 match = MATCH_BOTH;
633 }
634 if (*p != ',' && *p != '\0')
635 return MATCH_NONE;
636 return match;
637 }
638
639 /*
640 * Remove method from the start of a comma-separated list of methods.
641 * Returns 0 if the list of methods did not start with that method or 1
642 * if it did.
643 */
644 static int
remove_method(char ** methods,const char * method,const char * submethod)645 remove_method(char **methods, const char *method, const char *submethod)
646 {
647 char *omethods = *methods, *p;
648 size_t l = strlen(method);
649 int match;
650
651 match = list_starts_with(omethods, method, submethod);
652 if (match != MATCH_METHOD && match != MATCH_BOTH)
653 return 0;
654 p = omethods + l;
655 if (submethod && match == MATCH_BOTH)
656 p += 1 + strlen(submethod); /* include colon */
657 if (*p == ',')
658 p++;
659 *methods = xstrdup(p);
660 free(omethods);
661 return 1;
662 }
663
664 /*
665 * Called after successful authentication. Will remove the successful method
666 * from the start of each list in which it occurs. If it was the last method
667 * in any list, then authentication is deemed successful.
668 * Returns 1 if the method completed any authentication list or 0 otherwise.
669 */
670 int
auth2_update_methods_lists(Authctxt * authctxt,const char * method,const char * submethod)671 auth2_update_methods_lists(Authctxt *authctxt, const char *method,
672 const char *submethod)
673 {
674 u_int i, found = 0;
675
676 debug3("%s: updating methods list after \"%s\"", __func__, method);
677 for (i = 0; i < authctxt->num_auth_methods; i++) {
678 if (!remove_method(&(authctxt->auth_methods[i]), method,
679 submethod))
680 continue;
681 found = 1;
682 if (*authctxt->auth_methods[i] == '\0') {
683 debug2("authentication methods list %d complete", i);
684 return 1;
685 }
686 debug3("authentication methods list %d remaining: \"%s\"",
687 i, authctxt->auth_methods[i]);
688 }
689 /* This should not happen, but would be bad if it did */
690 if (!found)
691 fatal("%s: method not in AuthenticationMethods", __func__);
692 return 0;
693 }
694
695 /* Reset method-specific information */
auth2_authctxt_reset_info(Authctxt * authctxt)696 void auth2_authctxt_reset_info(Authctxt *authctxt)
697 {
698 sshkey_free(authctxt->auth_method_key);
699 free(authctxt->auth_method_info);
700 authctxt->auth_method_key = NULL;
701 authctxt->auth_method_info = NULL;
702 }
703
704 /* Record auth method-specific information for logs */
705 void
auth2_record_info(Authctxt * authctxt,const char * fmt,...)706 auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
707 {
708 va_list ap;
709 int i;
710
711 free(authctxt->auth_method_info);
712 authctxt->auth_method_info = NULL;
713
714 va_start(ap, fmt);
715 i = vasprintf(&authctxt->auth_method_info, fmt, ap);
716 va_end(ap);
717
718 if (i == -1)
719 fatal("%s: vasprintf failed", __func__);
720 }
721
722 /*
723 * Records a public key used in authentication. This is used for logging
724 * and to ensure that the same key is not subsequently accepted again for
725 * multiple authentication.
726 */
727 void
auth2_record_key(Authctxt * authctxt,int authenticated,const struct sshkey * key)728 auth2_record_key(Authctxt *authctxt, int authenticated,
729 const struct sshkey *key)
730 {
731 struct sshkey **tmp, *dup;
732 int r;
733
734 if ((r = sshkey_from_private(key, &dup)) != 0)
735 fatal("%s: copy key: %s", __func__, ssh_err(r));
736 sshkey_free(authctxt->auth_method_key);
737 authctxt->auth_method_key = dup;
738
739 if (!authenticated)
740 return;
741
742 /* If authenticated, make sure we don't accept this key again */
743 if ((r = sshkey_from_private(key, &dup)) != 0)
744 fatal("%s: copy key: %s", __func__, ssh_err(r));
745 if (authctxt->nprev_keys >= INT_MAX ||
746 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
747 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
748 fatal("%s: reallocarray failed", __func__);
749 authctxt->prev_keys = tmp;
750 authctxt->prev_keys[authctxt->nprev_keys] = dup;
751 authctxt->nprev_keys++;
752
753 }
754
755 /* Checks whether a key has already been previously used for authentication */
756 int
auth2_key_already_used(Authctxt * authctxt,const struct sshkey * key)757 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
758 {
759 u_int i;
760 char *fp;
761
762 for (i = 0; i < authctxt->nprev_keys; i++) {
763 if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
764 fp = sshkey_fingerprint(authctxt->prev_keys[i],
765 options.fingerprint_hash, SSH_FP_DEFAULT);
766 debug3("%s: key already used: %s %s", __func__,
767 sshkey_type(authctxt->prev_keys[i]),
768 fp == NULL ? "UNKNOWN" : fp);
769 free(fp);
770 return 1;
771 }
772 }
773 return 0;
774 }
775
776 /*
777 * Updates authctxt->session_info with details of authentication. Should be
778 * whenever an authentication method succeeds.
779 */
780 void
auth2_update_session_info(Authctxt * authctxt,const char * method,const char * submethod)781 auth2_update_session_info(Authctxt *authctxt, const char *method,
782 const char *submethod)
783 {
784 int r;
785
786 if (authctxt->session_info == NULL) {
787 if ((authctxt->session_info = sshbuf_new()) == NULL)
788 fatal("%s: sshbuf_new", __func__);
789 }
790
791 /* Append method[/submethod] */
792 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
793 method, submethod == NULL ? "" : "/",
794 submethod == NULL ? "" : submethod)) != 0)
795 fatal("%s: append method: %s", __func__, ssh_err(r));
796
797 /* Append key if present */
798 if (authctxt->auth_method_key != NULL) {
799 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
800 (r = sshkey_format_text(authctxt->auth_method_key,
801 authctxt->session_info)) != 0)
802 fatal("%s: append key: %s", __func__, ssh_err(r));
803 }
804
805 if (authctxt->auth_method_info != NULL) {
806 /* Ensure no ambiguity here */
807 if (strchr(authctxt->auth_method_info, '\n') != NULL)
808 fatal("%s: auth_method_info contains \\n", __func__);
809 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
810 (r = sshbuf_putf(authctxt->session_info, "%s",
811 authctxt->auth_method_info)) != 0) {
812 fatal("%s: append method info: %s",
813 __func__, ssh_err(r));
814 }
815 }
816 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
817 fatal("%s: append: %s", __func__, ssh_err(r));
818 }
819
820