1 /* $OpenBSD: auth2.c,v 1.169 2024/05/17 00:30:23 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 "sshkey.h"
50 #include "hostfile.h"
51 #include "auth.h"
52 #include "dispatch.h"
53 #include "pathnames.h"
54 #include "ssherr.h"
55 #ifdef GSSAPI
56 #include "ssh-gss.h"
57 #endif
58 #include "monitor_wrap.h"
59 #include "digest.h"
60 #include "kex.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_byname(const char *);
96 static Authmethod *authmethod_lookup(Authctxt *, const char *);
97 static char *authmethods_get(Authctxt *authctxt);
98
99 #define MATCH_NONE 0 /* method or submethod mismatch */
100 #define MATCH_METHOD 1 /* method matches (no submethod specified) */
101 #define MATCH_BOTH 2 /* method and submethod match */
102 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */
103 static int list_starts_with(const char *, const char *, const char *);
104
105 char *
auth2_read_banner(void)106 auth2_read_banner(void)
107 {
108 struct stat st;
109 char *banner = NULL;
110 size_t len, n;
111 int fd;
112
113 if ((fd = open(options.banner, O_RDONLY)) == -1)
114 return (NULL);
115 if (fstat(fd, &st) == -1) {
116 close(fd);
117 return (NULL);
118 }
119 if (st.st_size <= 0 || st.st_size > 1*1024*1024) {
120 close(fd);
121 return (NULL);
122 }
123
124 len = (size_t)st.st_size; /* truncate */
125 banner = xmalloc(len + 1);
126 n = atomicio(read, fd, banner, len);
127 close(fd);
128
129 if (n != len) {
130 free(banner);
131 return (NULL);
132 }
133 banner[n] = '\0';
134
135 return (banner);
136 }
137
138 static void
userauth_send_banner(struct ssh * ssh,const char * msg)139 userauth_send_banner(struct ssh *ssh, const char *msg)
140 {
141 int r;
142
143 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 ||
144 (r = sshpkt_put_cstring(ssh, msg)) != 0 ||
145 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */
146 (r = sshpkt_send(ssh)) != 0)
147 fatal_fr(r, "send packet");
148 debug("%s: sent", __func__);
149 }
150
151 static void
userauth_banner(struct ssh * ssh)152 userauth_banner(struct ssh *ssh)
153 {
154 char *banner = NULL;
155
156 if (options.banner == NULL)
157 return;
158
159 if ((banner = mm_auth2_read_banner()) == NULL)
160 goto done;
161 userauth_send_banner(ssh, banner);
162
163 done:
164 free(banner);
165 }
166
167 /*
168 * loop until authctxt->success == TRUE
169 */
170 void
do_authentication2(struct ssh * ssh)171 do_authentication2(struct ssh *ssh)
172 {
173 Authctxt *authctxt = ssh->authctxt;
174
175 ssh_dispatch_init(ssh, &dispatch_protocol_error);
176 if (ssh->kex->ext_info_c)
177 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_input_ext_info);
178 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request);
179 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success);
180 ssh->authctxt = NULL;
181 }
182
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 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &dispatch_protocol_error);
218 r = 0;
219 out:
220 free(service);
221 return r;
222 }
223
224 #define MIN_FAIL_DELAY_SECONDS 0.005
225 #define MAX_FAIL_DELAY_SECONDS 5.0
226 static double
user_specific_delay(const char * user)227 user_specific_delay(const char *user)
228 {
229 char b[512];
230 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512);
231 u_char *hash = xmalloc(len);
232 double delay;
233
234 (void)snprintf(b, sizeof b, "%llu%s",
235 (unsigned long long)options.timing_secret, user);
236 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0)
237 fatal_f("ssh_digest_memory");
238 /* 0-4.2 ms of delay */
239 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000;
240 freezero(hash, len);
241 debug3_f("user specific delay %0.3lfms", delay/1000);
242 return MIN_FAIL_DELAY_SECONDS + delay;
243 }
244
245 static void
ensure_minimum_time_since(double start,double seconds)246 ensure_minimum_time_since(double start, double seconds)
247 {
248 struct timespec ts;
249 double elapsed = monotime_double() - start, req = seconds, remain;
250
251 if (elapsed > MAX_FAIL_DELAY_SECONDS) {
252 debug3_f("elapsed %0.3lfms exceeded the max delay "
253 "requested %0.3lfms)", elapsed*1000, req*1000);
254 return;
255 }
256
257 /* if we've already passed the requested time, scale up */
258 while ((remain = seconds - elapsed) < 0.0)
259 seconds *= 2;
260
261 ts.tv_sec = remain;
262 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000;
263 debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)",
264 elapsed*1000, remain*1000, req*1000);
265 nanosleep(&ts, NULL);
266 }
267
268 static int
input_userauth_request(int type,u_int32_t seq,struct ssh * ssh)269 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh)
270 {
271 Authctxt *authctxt = ssh->authctxt;
272 Authmethod *m = NULL;
273 char *user = NULL, *service = NULL, *method = NULL, *style = NULL;
274 int r, authenticated = 0;
275 double tstart = monotime_double();
276
277 if (authctxt == NULL)
278 fatal("input_userauth_request: no authctxt");
279
280 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 ||
281 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 ||
282 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0)
283 goto out;
284 debug("userauth-request for user %s service %s method %s", user, service, method);
285 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures);
286
287 if ((style = strchr(user, ':')) != NULL)
288 *style++ = 0;
289
290 if (authctxt->attempt >= 1024)
291 auth_maxtries_exceeded(ssh);
292 if (authctxt->attempt++ == 0) {
293 /* setup auth context */
294 authctxt->pw = mm_getpwnamallow(ssh, user);
295 authctxt->user = xstrdup(user);
296 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
297 authctxt->valid = 1;
298 debug2_f("setting up authctxt for %s", user);
299 } else {
300 authctxt->valid = 0;
301 /* Invalid user, fake password information */
302 authctxt->pw = fakepw();
303 #ifdef SSH_AUDIT_EVENTS
304 mm_audit_event(ssh, SSH_INVALID_USER);
305 #endif
306 }
307 #ifdef USE_PAM
308 if (options.use_pam)
309 mm_start_pam(ssh);
310 #endif
311 ssh_packet_set_log_preamble(ssh, "%suser %s",
312 authctxt->valid ? "authenticating " : "invalid ", user);
313 setproctitle("%s [net]", authctxt->valid ? user : "unknown");
314 authctxt->service = xstrdup(service);
315 authctxt->style = style ? xstrdup(style) : NULL;
316 mm_inform_authserv(service, style);
317 userauth_banner(ssh);
318 if ((r = kex_server_update_ext_info(ssh)) != 0)
319 fatal_fr(r, "kex_server_update_ext_info failed");
320 if (auth2_setup_methods_lists(authctxt) != 0)
321 ssh_packet_disconnect(ssh,
322 "no authentication methods enabled");
323 } else if (strcmp(user, authctxt->user) != 0 ||
324 strcmp(service, authctxt->service) != 0) {
325 ssh_packet_disconnect(ssh, "Change of username or service "
326 "not allowed: (%s,%s) -> (%s,%s)",
327 authctxt->user, authctxt->service, user, service);
328 }
329 /* reset state */
330 auth2_challenge_stop(ssh);
331
332 #ifdef GSSAPI
333 /* XXX move to auth2_gssapi_stop() */
334 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL);
335 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL);
336 #endif
337
338 auth2_authctxt_reset_info(authctxt);
339 authctxt->postponed = 0;
340 authctxt->server_caused_failure = 0;
341
342 /* try to authenticate user */
343 m = authmethod_lookup(authctxt, method);
344 if (m != NULL && authctxt->failures < options.max_authtries) {
345 debug2("input_userauth_request: try method %s", method);
346 authenticated = m->userauth(ssh, method);
347 }
348 if (!authctxt->authenticated && strcmp(method, "none") != 0)
349 ensure_minimum_time_since(tstart,
350 user_specific_delay(authctxt->user));
351 userauth_finish(ssh, authenticated, method, NULL);
352 r = 0;
353 out:
354 free(service);
355 free(user);
356 free(method);
357 return r;
358 }
359
360 void
userauth_finish(struct ssh * ssh,int authenticated,const char * packet_method,const char * submethod)361 userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method,
362 const char *submethod)
363 {
364 Authctxt *authctxt = ssh->authctxt;
365 Authmethod *m = NULL;
366 const char *method = packet_method;
367 char *methods;
368 int r, partial = 0;
369
370 if (authenticated) {
371 if (!authctxt->valid) {
372 fatal("INTERNAL ERROR: authenticated invalid user %s",
373 authctxt->user);
374 }
375 if (authctxt->postponed)
376 fatal("INTERNAL ERROR: authenticated and postponed");
377 /* prefer primary authmethod name to possible synonym */
378 if ((m = authmethod_byname(method)) == NULL)
379 fatal("INTERNAL ERROR: bad method %s", method);
380 method = m->cfg->name;
381 }
382
383 /* Special handling for root */
384 if (authenticated && authctxt->pw->pw_uid == 0 &&
385 !auth_root_allowed(ssh, method)) {
386 authenticated = 0;
387 #ifdef SSH_AUDIT_EVENTS
388 mm_audit_event(ssh, SSH_LOGIN_ROOT_DENIED);
389 #endif
390 }
391
392 if (authenticated && options.num_auth_methods != 0) {
393 if (!auth2_update_methods_lists(authctxt, method, submethod)) {
394 authenticated = 0;
395 partial = 1;
396 }
397 }
398
399 /* Log before sending the reply */
400 auth_log(ssh, authenticated, partial, method, submethod);
401
402 /* Update information exposed to session */
403 if (authenticated || partial)
404 auth2_update_session_info(authctxt, method, submethod);
405
406 if (authctxt->postponed)
407 return;
408
409 #ifdef USE_PAM
410 if (options.use_pam && authenticated) {
411 int r, success = mm_do_pam_account();
412
413 /* If PAM returned a message, send it to the user. */
414 if (sshbuf_len(loginmsg) > 0) {
415 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0)
416 fatal("%s: buffer error: %s",
417 __func__, ssh_err(r));
418 userauth_send_banner(ssh, sshbuf_ptr(loginmsg));
419 if ((r = ssh_packet_write_wait(ssh)) != 0) {
420 sshpkt_fatal(ssh, r,
421 "%s: send PAM banner", __func__);
422 }
423 }
424 if (!success) {
425 fatal("Access denied for user %s by PAM account "
426 "configuration", authctxt->user);
427 }
428 }
429 #endif
430
431 if (authenticated == 1) {
432 /* turn off userauth */
433 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST,
434 &dispatch_protocol_ignore);
435 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 ||
436 (r = sshpkt_send(ssh)) != 0 ||
437 (r = ssh_packet_write_wait(ssh)) != 0)
438 fatal_fr(r, "send success packet");
439 /* now we can break out */
440 authctxt->success = 1;
441 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
442 } else {
443 /* Allow initial try of "none" auth without failure penalty */
444 if (!partial && !authctxt->server_caused_failure &&
445 (authctxt->attempt > 1 || strcmp(method, "none") != 0))
446 authctxt->failures++;
447 if (authctxt->failures >= options.max_authtries) {
448 #ifdef SSH_AUDIT_EVENTS
449 mm_audit_event(ssh, SSH_LOGIN_EXCEED_MAXTRIES);
450 #endif
451 auth_maxtries_exceeded(ssh);
452 }
453 methods = authmethods_get(authctxt);
454 debug3_f("failure partial=%d next methods=\"%s\"",
455 partial, methods);
456 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 ||
457 (r = sshpkt_put_cstring(ssh, methods)) != 0 ||
458 (r = sshpkt_put_u8(ssh, partial)) != 0 ||
459 (r = sshpkt_send(ssh)) != 0 ||
460 (r = ssh_packet_write_wait(ssh)) != 0)
461 fatal_fr(r, "send failure packet");
462 free(methods);
463 }
464 }
465
466 /*
467 * Checks whether method is allowed by at least one AuthenticationMethods
468 * methods list. Returns 1 if allowed, or no methods lists configured.
469 * 0 otherwise.
470 */
471 int
auth2_method_allowed(Authctxt * authctxt,const char * method,const char * submethod)472 auth2_method_allowed(Authctxt *authctxt, const char *method,
473 const char *submethod)
474 {
475 u_int i;
476
477 /*
478 * NB. authctxt->num_auth_methods might be zero as a result of
479 * auth2_setup_methods_lists(), so check the configuration.
480 */
481 if (options.num_auth_methods == 0)
482 return 1;
483 for (i = 0; i < authctxt->num_auth_methods; i++) {
484 if (list_starts_with(authctxt->auth_methods[i], method,
485 submethod) != MATCH_NONE)
486 return 1;
487 }
488 return 0;
489 }
490
491 static char *
authmethods_get(Authctxt * authctxt)492 authmethods_get(Authctxt *authctxt)
493 {
494 struct sshbuf *b;
495 char *list;
496 int i, r;
497
498 if ((b = sshbuf_new()) == NULL)
499 fatal_f("sshbuf_new failed");
500 for (i = 0; authmethods[i] != NULL; i++) {
501 if (strcmp(authmethods[i]->cfg->name, "none") == 0)
502 continue;
503 if (authmethods[i]->cfg->enabled == NULL ||
504 *(authmethods[i]->cfg->enabled) == 0)
505 continue;
506 if (!auth2_method_allowed(authctxt, authmethods[i]->cfg->name,
507 NULL))
508 continue;
509 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "",
510 authmethods[i]->cfg->name)) != 0)
511 fatal_fr(r, "buffer error");
512 }
513 if ((list = sshbuf_dup_string(b)) == NULL)
514 fatal_f("sshbuf_dup_string failed");
515 sshbuf_free(b);
516 return list;
517 }
518
519 static Authmethod *
authmethod_byname(const char * name)520 authmethod_byname(const char *name)
521 {
522 int i;
523
524 if (name == NULL)
525 fatal_f("NULL authentication method name");
526 for (i = 0; authmethods[i] != NULL; i++) {
527 if (strcmp(name, authmethods[i]->cfg->name) == 0 ||
528 (authmethods[i]->cfg->synonym != NULL &&
529 strcmp(name, authmethods[i]->cfg->synonym) == 0))
530 return authmethods[i];
531 }
532 debug_f("unrecognized authentication method name: %s", name);
533 return NULL;
534 }
535
536 static Authmethod *
authmethod_lookup(Authctxt * authctxt,const char * name)537 authmethod_lookup(Authctxt *authctxt, const char *name)
538 {
539 Authmethod *method;
540
541 if ((method = authmethod_byname(name)) == NULL)
542 return NULL;
543
544 if (method->cfg->enabled == NULL || *(method->cfg->enabled) == 0) {
545 debug3_f("method %s not enabled", name);
546 return NULL;
547 }
548 if (!auth2_method_allowed(authctxt, method->cfg->name, NULL)) {
549 debug3_f("method %s not allowed "
550 "by AuthenticationMethods", name);
551 return NULL;
552 }
553 return method;
554 }
555
556 /*
557 * Prune the AuthenticationMethods supplied in the configuration, removing
558 * any methods lists that include disabled methods. Note that this might
559 * leave authctxt->num_auth_methods == 0, even when multiple required auth
560 * has been requested. For this reason, all tests for whether multiple is
561 * enabled should consult options.num_auth_methods directly.
562 */
563 int
auth2_setup_methods_lists(Authctxt * authctxt)564 auth2_setup_methods_lists(Authctxt *authctxt)
565 {
566 u_int i;
567
568 /* First, normalise away the "any" pseudo-method */
569 if (options.num_auth_methods == 1 &&
570 strcmp(options.auth_methods[0], "any") == 0) {
571 free(options.auth_methods[0]);
572 options.auth_methods[0] = NULL;
573 options.num_auth_methods = 0;
574 }
575
576 if (options.num_auth_methods == 0)
577 return 0;
578 debug3_f("checking methods");
579 authctxt->auth_methods = xcalloc(options.num_auth_methods,
580 sizeof(*authctxt->auth_methods));
581 authctxt->num_auth_methods = 0;
582 for (i = 0; i < options.num_auth_methods; i++) {
583 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) {
584 logit("Authentication methods list \"%s\" contains "
585 "disabled method, skipping",
586 options.auth_methods[i]);
587 continue;
588 }
589 debug("authentication methods list %d: %s",
590 authctxt->num_auth_methods, options.auth_methods[i]);
591 authctxt->auth_methods[authctxt->num_auth_methods++] =
592 xstrdup(options.auth_methods[i]);
593 }
594 if (authctxt->num_auth_methods == 0) {
595 error("No AuthenticationMethods left after eliminating "
596 "disabled methods");
597 return -1;
598 }
599 return 0;
600 }
601
602 static int
list_starts_with(const char * methods,const char * method,const char * submethod)603 list_starts_with(const char *methods, const char *method,
604 const char *submethod)
605 {
606 size_t l = strlen(method);
607 int match;
608 const char *p;
609
610 if (strncmp(methods, method, l) != 0)
611 return MATCH_NONE;
612 p = methods + l;
613 match = MATCH_METHOD;
614 if (*p == ':') {
615 if (!submethod)
616 return MATCH_PARTIAL;
617 l = strlen(submethod);
618 p += 1;
619 if (strncmp(submethod, p, l))
620 return MATCH_NONE;
621 p += l;
622 match = MATCH_BOTH;
623 }
624 if (*p != ',' && *p != '\0')
625 return MATCH_NONE;
626 return match;
627 }
628
629 /*
630 * Remove method from the start of a comma-separated list of methods.
631 * Returns 0 if the list of methods did not start with that method or 1
632 * if it did.
633 */
634 static int
remove_method(char ** methods,const char * method,const char * submethod)635 remove_method(char **methods, const char *method, const char *submethod)
636 {
637 char *omethods = *methods, *p;
638 size_t l = strlen(method);
639 int match;
640
641 match = list_starts_with(omethods, method, submethod);
642 if (match != MATCH_METHOD && match != MATCH_BOTH)
643 return 0;
644 p = omethods + l;
645 if (submethod && match == MATCH_BOTH)
646 p += 1 + strlen(submethod); /* include colon */
647 if (*p == ',')
648 p++;
649 *methods = xstrdup(p);
650 free(omethods);
651 return 1;
652 }
653
654 /*
655 * Called after successful authentication. Will remove the successful method
656 * from the start of each list in which it occurs. If it was the last method
657 * in any list, then authentication is deemed successful.
658 * Returns 1 if the method completed any authentication list or 0 otherwise.
659 */
660 int
auth2_update_methods_lists(Authctxt * authctxt,const char * method,const char * submethod)661 auth2_update_methods_lists(Authctxt *authctxt, const char *method,
662 const char *submethod)
663 {
664 u_int i, found = 0;
665
666 debug3_f("updating methods list after \"%s\"", method);
667 for (i = 0; i < authctxt->num_auth_methods; i++) {
668 if (!remove_method(&(authctxt->auth_methods[i]), method,
669 submethod))
670 continue;
671 found = 1;
672 if (*authctxt->auth_methods[i] == '\0') {
673 debug2("authentication methods list %d complete", i);
674 return 1;
675 }
676 debug3("authentication methods list %d remaining: \"%s\"",
677 i, authctxt->auth_methods[i]);
678 }
679 /* This should not happen, but would be bad if it did */
680 if (!found)
681 fatal_f("method not in AuthenticationMethods");
682 return 0;
683 }
684
685 /* Reset method-specific information */
auth2_authctxt_reset_info(Authctxt * authctxt)686 void auth2_authctxt_reset_info(Authctxt *authctxt)
687 {
688 sshkey_free(authctxt->auth_method_key);
689 free(authctxt->auth_method_info);
690 authctxt->auth_method_key = NULL;
691 authctxt->auth_method_info = NULL;
692 }
693
694 /* Record auth method-specific information for logs */
695 void
auth2_record_info(Authctxt * authctxt,const char * fmt,...)696 auth2_record_info(Authctxt *authctxt, const char *fmt, ...)
697 {
698 va_list ap;
699 int i;
700
701 free(authctxt->auth_method_info);
702 authctxt->auth_method_info = NULL;
703
704 va_start(ap, fmt);
705 i = vasprintf(&authctxt->auth_method_info, fmt, ap);
706 va_end(ap);
707
708 if (i == -1)
709 fatal_f("vasprintf failed");
710 }
711
712 /*
713 * Records a public key used in authentication. This is used for logging
714 * and to ensure that the same key is not subsequently accepted again for
715 * multiple authentication.
716 */
717 void
auth2_record_key(Authctxt * authctxt,int authenticated,const struct sshkey * key)718 auth2_record_key(Authctxt *authctxt, int authenticated,
719 const struct sshkey *key)
720 {
721 struct sshkey **tmp, *dup;
722 int r;
723
724 if ((r = sshkey_from_private(key, &dup)) != 0)
725 fatal_fr(r, "copy key");
726 sshkey_free(authctxt->auth_method_key);
727 authctxt->auth_method_key = dup;
728
729 if (!authenticated)
730 return;
731
732 /* If authenticated, make sure we don't accept this key again */
733 if ((r = sshkey_from_private(key, &dup)) != 0)
734 fatal_fr(r, "copy key");
735 if (authctxt->nprev_keys >= INT_MAX ||
736 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys,
737 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL)
738 fatal_f("reallocarray failed");
739 authctxt->prev_keys = tmp;
740 authctxt->prev_keys[authctxt->nprev_keys] = dup;
741 authctxt->nprev_keys++;
742
743 }
744
745 /* Checks whether a key has already been previously used for authentication */
746 int
auth2_key_already_used(Authctxt * authctxt,const struct sshkey * key)747 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key)
748 {
749 u_int i;
750 char *fp;
751
752 for (i = 0; i < authctxt->nprev_keys; i++) {
753 if (sshkey_equal_public(key, authctxt->prev_keys[i])) {
754 fp = sshkey_fingerprint(authctxt->prev_keys[i],
755 options.fingerprint_hash, SSH_FP_DEFAULT);
756 debug3_f("key already used: %s %s",
757 sshkey_type(authctxt->prev_keys[i]),
758 fp == NULL ? "UNKNOWN" : fp);
759 free(fp);
760 return 1;
761 }
762 }
763 return 0;
764 }
765
766 /*
767 * Updates authctxt->session_info with details of authentication. Should be
768 * whenever an authentication method succeeds.
769 */
770 void
auth2_update_session_info(Authctxt * authctxt,const char * method,const char * submethod)771 auth2_update_session_info(Authctxt *authctxt, const char *method,
772 const char *submethod)
773 {
774 int r;
775
776 if (authctxt->session_info == NULL) {
777 if ((authctxt->session_info = sshbuf_new()) == NULL)
778 fatal_f("sshbuf_new");
779 }
780
781 /* Append method[/submethod] */
782 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s",
783 method, submethod == NULL ? "" : "/",
784 submethod == NULL ? "" : submethod)) != 0)
785 fatal_fr(r, "append method");
786
787 /* Append key if present */
788 if (authctxt->auth_method_key != NULL) {
789 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
790 (r = sshkey_format_text(authctxt->auth_method_key,
791 authctxt->session_info)) != 0)
792 fatal_fr(r, "append key");
793 }
794
795 if (authctxt->auth_method_info != NULL) {
796 /* Ensure no ambiguity here */
797 if (strchr(authctxt->auth_method_info, '\n') != NULL)
798 fatal_f("auth_method_info contains \\n");
799 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 ||
800 (r = sshbuf_putf(authctxt->session_info, "%s",
801 authctxt->auth_method_info)) != 0) {
802 fatal_fr(r, "append method info");
803 }
804 }
805 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0)
806 fatal_fr(r, "append");
807 }
808
809