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(); 263 264 if (authctxt == NULL) 265 fatal("input_userauth_request: no authctxt"); 266 267 user = packet_get_cstring(NULL); 268 service = packet_get_cstring(NULL); 269 method = packet_get_cstring(NULL); 270 debug("userauth-request for user %s service %s method %s", user, service, method); 271 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 272 273 if ((style = strchr(user, ':')) != NULL) 274 *style++ = 0; 275 276 if (authctxt->attempt++ == 0) { 277 /* setup auth context */ 278 authctxt->pw = PRIVSEP(getpwnamallow(user)); 279 authctxt->user = xstrdup(user); 280 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 281 authctxt->valid = 1; 282 debug2("%s: setting up authctxt for %s", 283 __func__, user); 284 } else { 285 /* Invalid user, fake password information */ 286 authctxt->pw = fakepw(); 287 #ifdef SSH_AUDIT_EVENTS 288 PRIVSEP(audit_event(SSH_INVALID_USER)); 289 #endif 290 } 291 #ifdef USE_PAM 292 if (options.use_pam) 293 PRIVSEP(start_pam(authctxt)); 294 #endif 295 ssh_packet_set_log_preamble(ssh, "%suser %s", 296 authctxt->valid ? "authenticating " : "invalid ", user); 297 setproctitle("%s%s", authctxt->valid ? user : "unknown", 298 use_privsep ? " [net]" : ""); 299 authctxt->service = xstrdup(service); 300 authctxt->style = style ? xstrdup(style) : NULL; 301 if (use_privsep) 302 mm_inform_authserv(service, style); 303 userauth_banner(); 304 if (auth2_setup_methods_lists(authctxt) != 0) 305 packet_disconnect("no authentication methods enabled"); 306 } else if (strcmp(user, authctxt->user) != 0 || 307 strcmp(service, authctxt->service) != 0) { 308 packet_disconnect("Change of username or service not allowed: " 309 "(%s,%s) -> (%s,%s)", 310 authctxt->user, authctxt->service, user, service); 311 } 312 /* reset state */ 313 auth2_challenge_stop(ssh); 314 315 #ifdef GSSAPI 316 /* XXX move to auth2_gssapi_stop() */ 317 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 318 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 319 #endif 320 321 auth2_authctxt_reset_info(authctxt); 322 authctxt->postponed = 0; 323 authctxt->server_caused_failure = 0; 324 325 /* try to authenticate user */ 326 m = authmethod_lookup(authctxt, method); 327 if (m != NULL && authctxt->failures < options.max_authtries) { 328 debug2("input_userauth_request: try method %s", method); 329 authenticated = m->userauth(ssh); 330 } 331 if (!authctxt->authenticated) 332 ensure_minimum_time_since(tstart, 333 user_specific_delay(authctxt->user)); 334 userauth_finish(ssh, authenticated, method, NULL); 335 336 free(service); 337 free(user); 338 free(method); 339 return 0; 340 } 341 342 void 343 userauth_finish(struct ssh *ssh, int authenticated, const char *method, 344 const char *submethod) 345 { 346 Authctxt *authctxt = ssh->authctxt; 347 char *methods; 348 int partial = 0; 349 350 if (!authctxt->valid && authenticated) 351 fatal("INTERNAL ERROR: authenticated invalid user %s", 352 authctxt->user); 353 if (authenticated && authctxt->postponed) 354 fatal("INTERNAL ERROR: authenticated and postponed"); 355 356 /* Special handling for root */ 357 if (authenticated && authctxt->pw->pw_uid == 0 && 358 !auth_root_allowed(ssh, method)) { 359 authenticated = 0; 360 #ifdef SSH_AUDIT_EVENTS 361 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED)); 362 #endif 363 } 364 365 if (authenticated && options.num_auth_methods != 0) { 366 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 367 authenticated = 0; 368 partial = 1; 369 } 370 } 371 372 /* Log before sending the reply */ 373 auth_log(authctxt, authenticated, partial, method, submethod); 374 375 /* Update information exposed to session */ 376 if (authenticated || partial) 377 auth2_update_session_info(authctxt, method, submethod); 378 379 if (authctxt->postponed) 380 return; 381 382 #ifdef USE_PAM 383 if (options.use_pam && authenticated) { 384 int r; 385 386 if (!PRIVSEP(do_pam_account())) { 387 /* if PAM returned a message, send it to the user */ 388 if (sshbuf_len(loginmsg) > 0) { 389 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0) 390 fatal("%s: buffer error: %s", 391 __func__, ssh_err(r)); 392 userauth_send_banner(sshbuf_ptr(loginmsg)); 393 packet_write_wait(); 394 } 395 fatal("Access denied for user %s by PAM account " 396 "configuration", authctxt->user); 397 } 398 } 399 #endif 400 401 if (authenticated == 1) { 402 /* turn off userauth */ 403 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); 404 packet_start(SSH2_MSG_USERAUTH_SUCCESS); 405 packet_send(); 406 packet_write_wait(); 407 /* now we can break out */ 408 authctxt->success = 1; 409 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 410 } else { 411 /* Allow initial try of "none" auth without failure penalty */ 412 if (!partial && !authctxt->server_caused_failure && 413 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) { 414 authctxt->failures++; 415 BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL, "ssh"); 416 } 417 if (authctxt->failures >= options.max_authtries) { 418 #ifdef SSH_AUDIT_EVENTS 419 PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES)); 420 #endif 421 auth_maxtries_exceeded(authctxt); 422 } 423 methods = authmethods_get(authctxt); 424 debug3("%s: failure partial=%d next methods=\"%s\"", __func__, 425 partial, methods); 426 packet_start(SSH2_MSG_USERAUTH_FAILURE); 427 packet_put_cstring(methods); 428 packet_put_char(partial); 429 packet_send(); 430 packet_write_wait(); 431 free(methods); 432 } 433 } 434 435 /* 436 * Checks whether method is allowed by at least one AuthenticationMethods 437 * methods list. Returns 1 if allowed, or no methods lists configured. 438 * 0 otherwise. 439 */ 440 int 441 auth2_method_allowed(Authctxt *authctxt, const char *method, 442 const char *submethod) 443 { 444 u_int i; 445 446 /* 447 * NB. authctxt->num_auth_methods might be zero as a result of 448 * auth2_setup_methods_lists(), so check the configuration. 449 */ 450 if (options.num_auth_methods == 0) 451 return 1; 452 for (i = 0; i < authctxt->num_auth_methods; i++) { 453 if (list_starts_with(authctxt->auth_methods[i], method, 454 submethod) != MATCH_NONE) 455 return 1; 456 } 457 return 0; 458 } 459 460 static char * 461 authmethods_get(Authctxt *authctxt) 462 { 463 struct sshbuf *b; 464 char *list; 465 int i, r; 466 467 if ((b = sshbuf_new()) == NULL) 468 fatal("%s: sshbuf_new failed", __func__); 469 for (i = 0; authmethods[i] != NULL; i++) { 470 if (strcmp(authmethods[i]->name, "none") == 0) 471 continue; 472 if (authmethods[i]->enabled == NULL || 473 *(authmethods[i]->enabled) == 0) 474 continue; 475 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 476 NULL)) 477 continue; 478 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 479 authmethods[i]->name)) != 0) 480 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 481 } 482 if ((list = sshbuf_dup_string(b)) == NULL) 483 fatal("%s: sshbuf_dup_string failed", __func__); 484 sshbuf_free(b); 485 return list; 486 } 487 488 static Authmethod * 489 authmethod_lookup(Authctxt *authctxt, const char *name) 490 { 491 int i; 492 493 if (name != NULL) 494 for (i = 0; authmethods[i] != NULL; i++) 495 if (authmethods[i]->enabled != NULL && 496 *(authmethods[i]->enabled) != 0 && 497 strcmp(name, authmethods[i]->name) == 0 && 498 auth2_method_allowed(authctxt, 499 authmethods[i]->name, NULL)) 500 return authmethods[i]; 501 debug2("Unrecognized authentication method name: %s", 502 name ? name : "NULL"); 503 return NULL; 504 } 505 506 /* 507 * Check a comma-separated list of methods for validity. Is need_enable is 508 * non-zero, then also require that the methods are enabled. 509 * Returns 0 on success or -1 if the methods list is invalid. 510 */ 511 int 512 auth2_methods_valid(const char *_methods, int need_enable) 513 { 514 char *methods, *omethods, *method, *p; 515 u_int i, found; 516 int ret = -1; 517 518 if (*_methods == '\0') { 519 error("empty authentication method list"); 520 return -1; 521 } 522 omethods = methods = xstrdup(_methods); 523 while ((method = strsep(&methods, ",")) != NULL) { 524 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 525 if ((p = strchr(method, ':')) != NULL) 526 *p = '\0'; 527 if (strcmp(method, authmethods[i]->name) != 0) 528 continue; 529 if (need_enable) { 530 if (authmethods[i]->enabled == NULL || 531 *(authmethods[i]->enabled) == 0) { 532 error("Disabled method \"%s\" in " 533 "AuthenticationMethods list \"%s\"", 534 method, _methods); 535 goto out; 536 } 537 } 538 found = 1; 539 break; 540 } 541 if (!found) { 542 error("Unknown authentication method \"%s\" in list", 543 method); 544 goto out; 545 } 546 } 547 ret = 0; 548 out: 549 free(omethods); 550 return ret; 551 } 552 553 /* 554 * Prune the AuthenticationMethods supplied in the configuration, removing 555 * any methods lists that include disabled methods. Note that this might 556 * leave authctxt->num_auth_methods == 0, even when multiple required auth 557 * has been requested. For this reason, all tests for whether multiple is 558 * enabled should consult options.num_auth_methods directly. 559 */ 560 int 561 auth2_setup_methods_lists(Authctxt *authctxt) 562 { 563 u_int i; 564 565 if (options.num_auth_methods == 0) 566 return 0; 567 debug3("%s: checking methods", __func__); 568 authctxt->auth_methods = xcalloc(options.num_auth_methods, 569 sizeof(*authctxt->auth_methods)); 570 authctxt->num_auth_methods = 0; 571 for (i = 0; i < options.num_auth_methods; i++) { 572 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 573 logit("Authentication methods list \"%s\" contains " 574 "disabled method, skipping", 575 options.auth_methods[i]); 576 continue; 577 } 578 debug("authentication methods list %d: %s", 579 authctxt->num_auth_methods, options.auth_methods[i]); 580 authctxt->auth_methods[authctxt->num_auth_methods++] = 581 xstrdup(options.auth_methods[i]); 582 } 583 if (authctxt->num_auth_methods == 0) { 584 error("No AuthenticationMethods left after eliminating " 585 "disabled methods"); 586 return -1; 587 } 588 return 0; 589 } 590 591 static int 592 list_starts_with(const char *methods, const char *method, 593 const char *submethod) 594 { 595 size_t l = strlen(method); 596 int match; 597 const char *p; 598 599 if (strncmp(methods, method, l) != 0) 600 return MATCH_NONE; 601 p = methods + l; 602 match = MATCH_METHOD; 603 if (*p == ':') { 604 if (!submethod) 605 return MATCH_PARTIAL; 606 l = strlen(submethod); 607 p += 1; 608 if (strncmp(submethod, p, l)) 609 return MATCH_NONE; 610 p += l; 611 match = MATCH_BOTH; 612 } 613 if (*p != ',' && *p != '\0') 614 return MATCH_NONE; 615 return match; 616 } 617 618 /* 619 * Remove method from the start of a comma-separated list of methods. 620 * Returns 0 if the list of methods did not start with that method or 1 621 * if it did. 622 */ 623 static int 624 remove_method(char **methods, const char *method, const char *submethod) 625 { 626 char *omethods = *methods, *p; 627 size_t l = strlen(method); 628 int match; 629 630 match = list_starts_with(omethods, method, submethod); 631 if (match != MATCH_METHOD && match != MATCH_BOTH) 632 return 0; 633 p = omethods + l; 634 if (submethod && match == MATCH_BOTH) 635 p += 1 + strlen(submethod); /* include colon */ 636 if (*p == ',') 637 p++; 638 *methods = xstrdup(p); 639 free(omethods); 640 return 1; 641 } 642 643 /* 644 * Called after successful authentication. Will remove the successful method 645 * from the start of each list in which it occurs. If it was the last method 646 * in any list, then authentication is deemed successful. 647 * Returns 1 if the method completed any authentication list or 0 otherwise. 648 */ 649 int 650 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 651 const char *submethod) 652 { 653 u_int i, found = 0; 654 655 debug3("%s: updating methods list after \"%s\"", __func__, method); 656 for (i = 0; i < authctxt->num_auth_methods; i++) { 657 if (!remove_method(&(authctxt->auth_methods[i]), method, 658 submethod)) 659 continue; 660 found = 1; 661 if (*authctxt->auth_methods[i] == '\0') { 662 debug2("authentication methods list %d complete", i); 663 return 1; 664 } 665 debug3("authentication methods list %d remaining: \"%s\"", 666 i, authctxt->auth_methods[i]); 667 } 668 /* This should not happen, but would be bad if it did */ 669 if (!found) 670 fatal("%s: method not in AuthenticationMethods", __func__); 671 return 0; 672 } 673 674 /* Reset method-specific information */ 675 void auth2_authctxt_reset_info(Authctxt *authctxt) 676 { 677 sshkey_free(authctxt->auth_method_key); 678 free(authctxt->auth_method_info); 679 authctxt->auth_method_key = NULL; 680 authctxt->auth_method_info = NULL; 681 } 682 683 /* Record auth method-specific information for logs */ 684 void 685 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 686 { 687 va_list ap; 688 int i; 689 690 free(authctxt->auth_method_info); 691 authctxt->auth_method_info = NULL; 692 693 va_start(ap, fmt); 694 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 695 va_end(ap); 696 697 if (i < 0 || authctxt->auth_method_info == NULL) 698 fatal("%s: vasprintf failed", __func__); 699 } 700 701 /* 702 * Records a public key used in authentication. This is used for logging 703 * and to ensure that the same key is not subsequently accepted again for 704 * multiple authentication. 705 */ 706 void 707 auth2_record_key(Authctxt *authctxt, int authenticated, 708 const struct sshkey *key) 709 { 710 struct sshkey **tmp, *dup; 711 int r; 712 713 if ((r = sshkey_from_private(key, &dup)) != 0) 714 fatal("%s: copy key: %s", __func__, ssh_err(r)); 715 sshkey_free(authctxt->auth_method_key); 716 authctxt->auth_method_key = dup; 717 718 if (!authenticated) 719 return; 720 721 /* If authenticated, make sure we don't accept this key again */ 722 if ((r = sshkey_from_private(key, &dup)) != 0) 723 fatal("%s: copy key: %s", __func__, ssh_err(r)); 724 if (authctxt->nprev_keys >= INT_MAX || 725 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 726 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 727 fatal("%s: reallocarray failed", __func__); 728 authctxt->prev_keys = tmp; 729 authctxt->prev_keys[authctxt->nprev_keys] = dup; 730 authctxt->nprev_keys++; 731 732 } 733 734 /* Checks whether a key has already been previously used for authentication */ 735 int 736 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 737 { 738 u_int i; 739 char *fp; 740 741 for (i = 0; i < authctxt->nprev_keys; i++) { 742 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 743 fp = sshkey_fingerprint(authctxt->prev_keys[i], 744 options.fingerprint_hash, SSH_FP_DEFAULT); 745 debug3("%s: key already used: %s %s", __func__, 746 sshkey_type(authctxt->prev_keys[i]), 747 fp == NULL ? "UNKNOWN" : fp); 748 free(fp); 749 return 1; 750 } 751 } 752 return 0; 753 } 754 755 /* 756 * Updates authctxt->session_info with details of authentication. Should be 757 * whenever an authentication method succeeds. 758 */ 759 void 760 auth2_update_session_info(Authctxt *authctxt, const char *method, 761 const char *submethod) 762 { 763 int r; 764 765 if (authctxt->session_info == NULL) { 766 if ((authctxt->session_info = sshbuf_new()) == NULL) 767 fatal("%s: sshbuf_new", __func__); 768 } 769 770 /* Append method[/submethod] */ 771 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 772 method, submethod == NULL ? "" : "/", 773 submethod == NULL ? "" : submethod)) != 0) 774 fatal("%s: append method: %s", __func__, ssh_err(r)); 775 776 /* Append key if present */ 777 if (authctxt->auth_method_key != NULL) { 778 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 779 (r = sshkey_format_text(authctxt->auth_method_key, 780 authctxt->session_info)) != 0) 781 fatal("%s: append key: %s", __func__, ssh_err(r)); 782 } 783 784 if (authctxt->auth_method_info != NULL) { 785 /* Ensure no ambiguity here */ 786 if (strchr(authctxt->auth_method_info, '\n') != NULL) 787 fatal("%s: auth_method_info contains \\n", __func__); 788 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 789 (r = sshbuf_putf(authctxt->session_info, "%s", 790 authctxt->auth_method_info)) != 0) { 791 fatal("%s: append method info: %s", 792 __func__, ssh_err(r)); 793 } 794 } 795 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 796 fatal("%s: append: %s", __func__, ssh_err(r)); 797 } 798 799