1 /* $OpenBSD: auth2.c,v 1.149 2018/07/11 18:53:29 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 __RCSID("$FreeBSD$"); 28 29 #include <sys/types.h> 30 #include <sys/stat.h> 31 #include <sys/uio.h> 32 33 #include <fcntl.h> 34 #include <limits.h> 35 #include <pwd.h> 36 #include <stdarg.h> 37 #include <string.h> 38 #include <unistd.h> 39 40 #include "atomicio.h" 41 #include "xmalloc.h" 42 #include "ssh2.h" 43 #include "packet.h" 44 #include "log.h" 45 #include "sshbuf.h" 46 #include "misc.h" 47 #include "servconf.h" 48 #include "compat.h" 49 #include "sshkey.h" 50 #include "hostfile.h" 51 #include "auth.h" 52 #include "dispatch.h" 53 #include "pathnames.h" 54 #include "sshbuf.h" 55 #include "ssherr.h" 56 #include "blacklist_client.h" 57 58 #ifdef GSSAPI 59 #include "ssh-gss.h" 60 #endif 61 #include "monitor_wrap.h" 62 #include "ssherr.h" 63 #include "digest.h" 64 65 /* import */ 66 extern ServerOptions options; 67 extern u_char *session_id2; 68 extern u_int session_id2_len; 69 extern struct sshbuf *loginmsg; 70 71 /* methods */ 72 73 extern Authmethod method_none; 74 extern Authmethod method_pubkey; 75 extern Authmethod method_passwd; 76 extern Authmethod method_kbdint; 77 extern Authmethod method_hostbased; 78 #ifdef GSSAPI 79 extern Authmethod method_gssapi; 80 #endif 81 82 Authmethod *authmethods[] = { 83 &method_none, 84 &method_pubkey, 85 #ifdef GSSAPI 86 &method_gssapi, 87 #endif 88 &method_passwd, 89 &method_kbdint, 90 &method_hostbased, 91 NULL 92 }; 93 94 /* protocol */ 95 96 static int input_service_request(int, u_int32_t, struct ssh *); 97 static int input_userauth_request(int, u_int32_t, struct ssh *); 98 99 /* helper */ 100 static Authmethod *authmethod_lookup(Authctxt *, const char *); 101 static char *authmethods_get(Authctxt *authctxt); 102 103 #define MATCH_NONE 0 /* method or submethod mismatch */ 104 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 105 #define MATCH_BOTH 2 /* method and submethod match */ 106 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 107 static int list_starts_with(const char *, const char *, const char *); 108 109 char * 110 auth2_read_banner(void) 111 { 112 struct stat st; 113 char *banner = NULL; 114 size_t len, n; 115 int fd; 116 117 if ((fd = open(options.banner, O_RDONLY)) == -1) 118 return (NULL); 119 if (fstat(fd, &st) == -1) { 120 close(fd); 121 return (NULL); 122 } 123 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 124 close(fd); 125 return (NULL); 126 } 127 128 len = (size_t)st.st_size; /* truncate */ 129 banner = xmalloc(len + 1); 130 n = atomicio(read, fd, banner, len); 131 close(fd); 132 133 if (n != len) { 134 free(banner); 135 return (NULL); 136 } 137 banner[n] = '\0'; 138 139 return (banner); 140 } 141 142 void 143 userauth_send_banner(const char *msg) 144 { 145 packet_start(SSH2_MSG_USERAUTH_BANNER); 146 packet_put_cstring(msg); 147 packet_put_cstring(""); /* language, unused */ 148 packet_send(); 149 debug("%s: sent", __func__); 150 } 151 152 static void 153 userauth_banner(void) 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(banner); 163 164 done: 165 free(banner); 166 } 167 168 /* 169 * loop until authctxt->success == TRUE 170 */ 171 void 172 do_authentication2(Authctxt *authctxt) 173 { 174 struct ssh *ssh = active_state; /* XXX */ 175 ssh->authctxt = authctxt; /* XXX move to caller */ 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 184 input_service_request(int type, u_int32_t seq, struct ssh *ssh) 185 { 186 Authctxt *authctxt = ssh->authctxt; 187 u_int len; 188 int acceptit = 0; 189 char *service = packet_get_cstring(&len); 190 packet_check_eom(); 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, &input_userauth_request); 200 } 201 } 202 /* XXX all other service requests are denied */ 203 204 if (acceptit) { 205 packet_start(SSH2_MSG_SERVICE_ACCEPT); 206 packet_put_cstring(service); 207 packet_send(); 208 packet_write_wait(); 209 } else { 210 debug("bad service request %s", service); 211 packet_disconnect("bad service request %s", service); 212 } 213 free(service); 214 return 0; 215 } 216 217 #define MIN_FAIL_DELAY_SECONDS 0.005 218 static double 219 user_specific_delay(const char *user) 220 { 221 char b[512]; 222 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 223 u_char *hash = xmalloc(len); 224 double delay; 225 226 (void)snprintf(b, sizeof b, "%llu%s", 227 (unsigned long long)options.timing_secret, user); 228 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 229 fatal("%s: ssh_digest_memory", __func__); 230 /* 0-4.2 ms of delay */ 231 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 232 freezero(hash, len); 233 debug3("%s: user specific delay %0.3lfms", __func__, delay/1000); 234 return MIN_FAIL_DELAY_SECONDS + delay; 235 } 236 237 static void 238 ensure_minimum_time_since(double start, double seconds) 239 { 240 struct timespec ts; 241 double elapsed = monotime_double() - start, req = seconds, remain; 242 243 /* if we've already passed the requested time, scale up */ 244 while ((remain = seconds - elapsed) < 0.0) 245 seconds *= 2; 246 247 ts.tv_sec = remain; 248 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; 249 debug3("%s: elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 250 __func__, elapsed*1000, remain*1000, req*1000); 251 nanosleep(&ts, NULL); 252 } 253 254 /*ARGSUSED*/ 255 static int 256 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 257 { 258 Authctxt *authctxt = ssh->authctxt; 259 Authmethod *m = NULL; 260 char *user, *service, *method, *style = NULL; 261 int authenticated = 0; 262 double tstart = monotime_double(); 263 #ifdef HAVE_LOGIN_CAP 264 login_cap_t *lc; 265 const char *from_host, *from_ip; 266 #endif 267 268 if (authctxt == NULL) 269 fatal("input_userauth_request: no authctxt"); 270 271 user = packet_get_cstring(NULL); 272 service = packet_get_cstring(NULL); 273 method = packet_get_cstring(NULL); 274 debug("userauth-request for user %s service %s method %s", user, service, method); 275 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 276 277 if ((style = strchr(user, ':')) != NULL) 278 *style++ = 0; 279 280 if (authctxt->attempt++ == 0) { 281 /* setup auth context */ 282 authctxt->pw = PRIVSEP(getpwnamallow(user)); 283 authctxt->user = xstrdup(user); 284 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 285 authctxt->valid = 1; 286 debug2("%s: setting up authctxt for %s", 287 __func__, user); 288 } else { 289 /* Invalid user, fake password information */ 290 authctxt->pw = fakepw(); 291 #ifdef SSH_AUDIT_EVENTS 292 PRIVSEP(audit_event(SSH_INVALID_USER)); 293 #endif 294 } 295 #ifdef USE_PAM 296 if (options.use_pam) 297 PRIVSEP(start_pam(authctxt)); 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(); 308 if (auth2_setup_methods_lists(authctxt) != 0) 309 packet_disconnect("no authentication methods enabled"); 310 } else if (strcmp(user, authctxt->user) != 0 || 311 strcmp(service, authctxt->service) != 0) { 312 packet_disconnect("Change of username or service not allowed: " 313 "(%s,%s) -> (%s,%s)", 314 authctxt->user, authctxt->service, user, service); 315 } 316 317 #ifdef HAVE_LOGIN_CAP 318 if (authctxt->pw != NULL && 319 (lc = PRIVSEP(login_getpwclass(authctxt->pw))) != NULL) { 320 logit("user %s login class %s", authctxt->pw->pw_name, 321 authctxt->pw->pw_class); 322 from_host = auth_get_canonical_hostname(ssh, options.use_dns); 323 from_ip = ssh_remote_ipaddr(ssh); 324 if (!auth_hostok(lc, from_host, from_ip)) { 325 logit("Denied connection for %.200s from %.200s [%.200s].", 326 authctxt->pw->pw_name, from_host, from_ip); 327 packet_disconnect("Sorry, you are not allowed to connect."); 328 } 329 if (!auth_timeok(lc, time(NULL))) { 330 logit("LOGIN %.200s REFUSED (TIME) FROM %.200s", 331 authctxt->pw->pw_name, from_host); 332 packet_disconnect("Logins not available right now."); 333 } 334 PRIVSEP(login_close(lc)); 335 } 336 #endif /* HAVE_LOGIN_CAP */ 337 338 /* reset state */ 339 auth2_challenge_stop(ssh); 340 341 #ifdef GSSAPI 342 /* XXX move to auth2_gssapi_stop() */ 343 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 344 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 345 #endif 346 347 auth2_authctxt_reset_info(authctxt); 348 authctxt->postponed = 0; 349 authctxt->server_caused_failure = 0; 350 351 /* try to authenticate user */ 352 m = authmethod_lookup(authctxt, method); 353 if (m != NULL && authctxt->failures < options.max_authtries) { 354 debug2("input_userauth_request: try method %s", method); 355 authenticated = m->userauth(ssh); 356 } 357 if (!authctxt->authenticated) 358 ensure_minimum_time_since(tstart, 359 user_specific_delay(authctxt->user)); 360 userauth_finish(ssh, authenticated, method, NULL); 361 362 free(service); 363 free(user); 364 free(method); 365 return 0; 366 } 367 368 void 369 userauth_finish(struct ssh *ssh, int authenticated, const char *method, 370 const char *submethod) 371 { 372 Authctxt *authctxt = ssh->authctxt; 373 char *methods; 374 int partial = 0; 375 376 if (!authctxt->valid && authenticated) 377 fatal("INTERNAL ERROR: authenticated invalid user %s", 378 authctxt->user); 379 if (authenticated && authctxt->postponed) 380 fatal("INTERNAL ERROR: authenticated and postponed"); 381 382 /* Special handling for root */ 383 if (authenticated && authctxt->pw->pw_uid == 0 && 384 !auth_root_allowed(ssh, method)) { 385 authenticated = 0; 386 #ifdef SSH_AUDIT_EVENTS 387 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED)); 388 #endif 389 } 390 391 if (authenticated && options.num_auth_methods != 0) { 392 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 393 authenticated = 0; 394 partial = 1; 395 } 396 } 397 398 /* Log before sending the reply */ 399 auth_log(authctxt, authenticated, partial, method, submethod); 400 401 /* Update information exposed to session */ 402 if (authenticated || partial) 403 auth2_update_session_info(authctxt, method, submethod); 404 405 if (authctxt->postponed) 406 return; 407 408 #ifdef USE_PAM 409 if (options.use_pam && authenticated) { 410 int r; 411 412 if (!PRIVSEP(do_pam_account())) { 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(sshbuf_ptr(loginmsg)); 419 packet_write_wait(); 420 } 421 fatal("Access denied for user %s by PAM account " 422 "configuration", authctxt->user); 423 } 424 } 425 #endif 426 427 if (authenticated == 1) { 428 /* turn off userauth */ 429 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); 430 packet_start(SSH2_MSG_USERAUTH_SUCCESS); 431 packet_send(); 432 packet_write_wait(); 433 /* now we can break out */ 434 authctxt->success = 1; 435 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 436 } else { 437 /* Allow initial try of "none" auth without failure penalty */ 438 if (!partial && !authctxt->server_caused_failure && 439 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) { 440 authctxt->failures++; 441 BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL, "ssh"); 442 } 443 if (authctxt->failures >= options.max_authtries) { 444 #ifdef SSH_AUDIT_EVENTS 445 PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES)); 446 #endif 447 auth_maxtries_exceeded(authctxt); 448 } 449 methods = authmethods_get(authctxt); 450 debug3("%s: failure partial=%d next methods=\"%s\"", __func__, 451 partial, methods); 452 packet_start(SSH2_MSG_USERAUTH_FAILURE); 453 packet_put_cstring(methods); 454 packet_put_char(partial); 455 packet_send(); 456 packet_write_wait(); 457 free(methods); 458 } 459 } 460 461 /* 462 * Checks whether method is allowed by at least one AuthenticationMethods 463 * methods list. Returns 1 if allowed, or no methods lists configured. 464 * 0 otherwise. 465 */ 466 int 467 auth2_method_allowed(Authctxt *authctxt, const char *method, 468 const char *submethod) 469 { 470 u_int i; 471 472 /* 473 * NB. authctxt->num_auth_methods might be zero as a result of 474 * auth2_setup_methods_lists(), so check the configuration. 475 */ 476 if (options.num_auth_methods == 0) 477 return 1; 478 for (i = 0; i < authctxt->num_auth_methods; i++) { 479 if (list_starts_with(authctxt->auth_methods[i], method, 480 submethod) != MATCH_NONE) 481 return 1; 482 } 483 return 0; 484 } 485 486 static char * 487 authmethods_get(Authctxt *authctxt) 488 { 489 struct sshbuf *b; 490 char *list; 491 int i, r; 492 493 if ((b = sshbuf_new()) == NULL) 494 fatal("%s: sshbuf_new failed", __func__); 495 for (i = 0; authmethods[i] != NULL; i++) { 496 if (strcmp(authmethods[i]->name, "none") == 0) 497 continue; 498 if (authmethods[i]->enabled == NULL || 499 *(authmethods[i]->enabled) == 0) 500 continue; 501 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 502 NULL)) 503 continue; 504 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 505 authmethods[i]->name)) != 0) 506 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 507 } 508 if ((list = sshbuf_dup_string(b)) == NULL) 509 fatal("%s: sshbuf_dup_string failed", __func__); 510 sshbuf_free(b); 511 return list; 512 } 513 514 static Authmethod * 515 authmethod_lookup(Authctxt *authctxt, const char *name) 516 { 517 int i; 518 519 if (name != NULL) 520 for (i = 0; authmethods[i] != NULL; i++) 521 if (authmethods[i]->enabled != NULL && 522 *(authmethods[i]->enabled) != 0 && 523 strcmp(name, authmethods[i]->name) == 0 && 524 auth2_method_allowed(authctxt, 525 authmethods[i]->name, NULL)) 526 return authmethods[i]; 527 debug2("Unrecognized authentication method name: %s", 528 name ? name : "NULL"); 529 return NULL; 530 } 531 532 /* 533 * Check a comma-separated list of methods for validity. Is need_enable is 534 * non-zero, then also require that the methods are enabled. 535 * Returns 0 on success or -1 if the methods list is invalid. 536 */ 537 int 538 auth2_methods_valid(const char *_methods, int need_enable) 539 { 540 char *methods, *omethods, *method, *p; 541 u_int i, found; 542 int ret = -1; 543 544 if (*_methods == '\0') { 545 error("empty authentication method list"); 546 return -1; 547 } 548 omethods = methods = xstrdup(_methods); 549 while ((method = strsep(&methods, ",")) != NULL) { 550 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 551 if ((p = strchr(method, ':')) != NULL) 552 *p = '\0'; 553 if (strcmp(method, authmethods[i]->name) != 0) 554 continue; 555 if (need_enable) { 556 if (authmethods[i]->enabled == NULL || 557 *(authmethods[i]->enabled) == 0) { 558 error("Disabled method \"%s\" in " 559 "AuthenticationMethods list \"%s\"", 560 method, _methods); 561 goto out; 562 } 563 } 564 found = 1; 565 break; 566 } 567 if (!found) { 568 error("Unknown authentication method \"%s\" in list", 569 method); 570 goto out; 571 } 572 } 573 ret = 0; 574 out: 575 free(omethods); 576 return ret; 577 } 578 579 /* 580 * Prune the AuthenticationMethods supplied in the configuration, removing 581 * any methods lists that include disabled methods. Note that this might 582 * leave authctxt->num_auth_methods == 0, even when multiple required auth 583 * has been requested. For this reason, all tests for whether multiple is 584 * enabled should consult options.num_auth_methods directly. 585 */ 586 int 587 auth2_setup_methods_lists(Authctxt *authctxt) 588 { 589 u_int i; 590 591 if (options.num_auth_methods == 0) 592 return 0; 593 debug3("%s: checking methods", __func__); 594 authctxt->auth_methods = xcalloc(options.num_auth_methods, 595 sizeof(*authctxt->auth_methods)); 596 authctxt->num_auth_methods = 0; 597 for (i = 0; i < options.num_auth_methods; i++) { 598 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 599 logit("Authentication methods list \"%s\" contains " 600 "disabled method, skipping", 601 options.auth_methods[i]); 602 continue; 603 } 604 debug("authentication methods list %d: %s", 605 authctxt->num_auth_methods, options.auth_methods[i]); 606 authctxt->auth_methods[authctxt->num_auth_methods++] = 607 xstrdup(options.auth_methods[i]); 608 } 609 if (authctxt->num_auth_methods == 0) { 610 error("No AuthenticationMethods left after eliminating " 611 "disabled methods"); 612 return -1; 613 } 614 return 0; 615 } 616 617 static int 618 list_starts_with(const char *methods, const char *method, 619 const char *submethod) 620 { 621 size_t l = strlen(method); 622 int match; 623 const char *p; 624 625 if (strncmp(methods, method, l) != 0) 626 return MATCH_NONE; 627 p = methods + l; 628 match = MATCH_METHOD; 629 if (*p == ':') { 630 if (!submethod) 631 return MATCH_PARTIAL; 632 l = strlen(submethod); 633 p += 1; 634 if (strncmp(submethod, p, l)) 635 return MATCH_NONE; 636 p += l; 637 match = MATCH_BOTH; 638 } 639 if (*p != ',' && *p != '\0') 640 return MATCH_NONE; 641 return match; 642 } 643 644 /* 645 * Remove method from the start of a comma-separated list of methods. 646 * Returns 0 if the list of methods did not start with that method or 1 647 * if it did. 648 */ 649 static int 650 remove_method(char **methods, const char *method, const char *submethod) 651 { 652 char *omethods = *methods, *p; 653 size_t l = strlen(method); 654 int match; 655 656 match = list_starts_with(omethods, method, submethod); 657 if (match != MATCH_METHOD && match != MATCH_BOTH) 658 return 0; 659 p = omethods + l; 660 if (submethod && match == MATCH_BOTH) 661 p += 1 + strlen(submethod); /* include colon */ 662 if (*p == ',') 663 p++; 664 *methods = xstrdup(p); 665 free(omethods); 666 return 1; 667 } 668 669 /* 670 * Called after successful authentication. Will remove the successful method 671 * from the start of each list in which it occurs. If it was the last method 672 * in any list, then authentication is deemed successful. 673 * Returns 1 if the method completed any authentication list or 0 otherwise. 674 */ 675 int 676 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 677 const char *submethod) 678 { 679 u_int i, found = 0; 680 681 debug3("%s: updating methods list after \"%s\"", __func__, method); 682 for (i = 0; i < authctxt->num_auth_methods; i++) { 683 if (!remove_method(&(authctxt->auth_methods[i]), method, 684 submethod)) 685 continue; 686 found = 1; 687 if (*authctxt->auth_methods[i] == '\0') { 688 debug2("authentication methods list %d complete", i); 689 return 1; 690 } 691 debug3("authentication methods list %d remaining: \"%s\"", 692 i, authctxt->auth_methods[i]); 693 } 694 /* This should not happen, but would be bad if it did */ 695 if (!found) 696 fatal("%s: method not in AuthenticationMethods", __func__); 697 return 0; 698 } 699 700 /* Reset method-specific information */ 701 void auth2_authctxt_reset_info(Authctxt *authctxt) 702 { 703 sshkey_free(authctxt->auth_method_key); 704 free(authctxt->auth_method_info); 705 authctxt->auth_method_key = NULL; 706 authctxt->auth_method_info = NULL; 707 } 708 709 /* Record auth method-specific information for logs */ 710 void 711 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 712 { 713 va_list ap; 714 int i; 715 716 free(authctxt->auth_method_info); 717 authctxt->auth_method_info = NULL; 718 719 va_start(ap, fmt); 720 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 721 va_end(ap); 722 723 if (i < 0 || authctxt->auth_method_info == NULL) 724 fatal("%s: vasprintf failed", __func__); 725 } 726 727 /* 728 * Records a public key used in authentication. This is used for logging 729 * and to ensure that the same key is not subsequently accepted again for 730 * multiple authentication. 731 */ 732 void 733 auth2_record_key(Authctxt *authctxt, int authenticated, 734 const struct sshkey *key) 735 { 736 struct sshkey **tmp, *dup; 737 int r; 738 739 if ((r = sshkey_from_private(key, &dup)) != 0) 740 fatal("%s: copy key: %s", __func__, ssh_err(r)); 741 sshkey_free(authctxt->auth_method_key); 742 authctxt->auth_method_key = dup; 743 744 if (!authenticated) 745 return; 746 747 /* If authenticated, make sure we don't accept this key again */ 748 if ((r = sshkey_from_private(key, &dup)) != 0) 749 fatal("%s: copy key: %s", __func__, ssh_err(r)); 750 if (authctxt->nprev_keys >= INT_MAX || 751 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 752 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 753 fatal("%s: reallocarray failed", __func__); 754 authctxt->prev_keys = tmp; 755 authctxt->prev_keys[authctxt->nprev_keys] = dup; 756 authctxt->nprev_keys++; 757 758 } 759 760 /* Checks whether a key has already been previously used for authentication */ 761 int 762 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 763 { 764 u_int i; 765 char *fp; 766 767 for (i = 0; i < authctxt->nprev_keys; i++) { 768 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 769 fp = sshkey_fingerprint(authctxt->prev_keys[i], 770 options.fingerprint_hash, SSH_FP_DEFAULT); 771 debug3("%s: key already used: %s %s", __func__, 772 sshkey_type(authctxt->prev_keys[i]), 773 fp == NULL ? "UNKNOWN" : fp); 774 free(fp); 775 return 1; 776 } 777 } 778 return 0; 779 } 780 781 /* 782 * Updates authctxt->session_info with details of authentication. Should be 783 * whenever an authentication method succeeds. 784 */ 785 void 786 auth2_update_session_info(Authctxt *authctxt, const char *method, 787 const char *submethod) 788 { 789 int r; 790 791 if (authctxt->session_info == NULL) { 792 if ((authctxt->session_info = sshbuf_new()) == NULL) 793 fatal("%s: sshbuf_new", __func__); 794 } 795 796 /* Append method[/submethod] */ 797 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 798 method, submethod == NULL ? "" : "/", 799 submethod == NULL ? "" : submethod)) != 0) 800 fatal("%s: append method: %s", __func__, ssh_err(r)); 801 802 /* Append key if present */ 803 if (authctxt->auth_method_key != NULL) { 804 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 805 (r = sshkey_format_text(authctxt->auth_method_key, 806 authctxt->session_info)) != 0) 807 fatal("%s: append key: %s", __func__, ssh_err(r)); 808 } 809 810 if (authctxt->auth_method_info != NULL) { 811 /* Ensure no ambiguity here */ 812 if (strchr(authctxt->auth_method_info, '\n') != NULL) 813 fatal("%s: auth_method_info contains \\n", __func__); 814 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 815 (r = sshbuf_putf(authctxt->session_info, "%s", 816 authctxt->auth_method_info)) != 0) { 817 fatal("%s: append method info: %s", 818 __func__, ssh_err(r)); 819 } 820 } 821 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 822 fatal("%s: append: %s", __func__, ssh_err(r)); 823 } 824 825