1 /* $OpenBSD: auth2.c,v 1.143 2017/06/24 06:34:38 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 __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 "buffer.h" 46 #include "misc.h" 47 #include "servconf.h" 48 #include "compat.h" 49 #include "key.h" 50 #include "hostfile.h" 51 #include "auth.h" 52 #include "dispatch.h" 53 #include "pathnames.h" 54 #include "buffer.h" 55 #include "blacklist_client.h" 56 57 #ifdef GSSAPI 58 #include "ssh-gss.h" 59 #endif 60 #include "monitor_wrap.h" 61 #include "ssherr.h" 62 63 /* import */ 64 extern ServerOptions options; 65 extern u_char *session_id2; 66 extern u_int session_id2_len; 67 extern Buffer loginmsg; 68 69 /* methods */ 70 71 extern Authmethod method_none; 72 extern Authmethod method_pubkey; 73 extern Authmethod method_passwd; 74 extern Authmethod method_kbdint; 75 extern Authmethod method_hostbased; 76 #ifdef GSSAPI 77 extern Authmethod method_gssapi; 78 #endif 79 80 Authmethod *authmethods[] = { 81 &method_none, 82 &method_pubkey, 83 #ifdef GSSAPI 84 &method_gssapi, 85 #endif 86 &method_passwd, 87 &method_kbdint, 88 &method_hostbased, 89 NULL 90 }; 91 92 /* protocol */ 93 94 static int input_service_request(int, u_int32_t, struct ssh *); 95 static int input_userauth_request(int, u_int32_t, struct ssh *); 96 97 /* helper */ 98 static Authmethod *authmethod_lookup(Authctxt *, const char *); 99 static char *authmethods_get(Authctxt *authctxt); 100 101 #define MATCH_NONE 0 /* method or submethod mismatch */ 102 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 103 #define MATCH_BOTH 2 /* method and submethod match */ 104 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 105 static int list_starts_with(const char *, const char *, const char *); 106 107 char * 108 auth2_read_banner(void) 109 { 110 struct stat st; 111 char *banner = NULL; 112 size_t len, n; 113 int fd; 114 115 if ((fd = open(options.banner, O_RDONLY)) == -1) 116 return (NULL); 117 if (fstat(fd, &st) == -1) { 118 close(fd); 119 return (NULL); 120 } 121 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 122 close(fd); 123 return (NULL); 124 } 125 126 len = (size_t)st.st_size; /* truncate */ 127 banner = xmalloc(len + 1); 128 n = atomicio(read, fd, banner, len); 129 close(fd); 130 131 if (n != len) { 132 free(banner); 133 return (NULL); 134 } 135 banner[n] = '\0'; 136 137 return (banner); 138 } 139 140 void 141 userauth_send_banner(const char *msg) 142 { 143 if (datafellows & SSH_BUG_BANNER) 144 return; 145 146 packet_start(SSH2_MSG_USERAUTH_BANNER); 147 packet_put_cstring(msg); 148 packet_put_cstring(""); /* language, unused */ 149 packet_send(); 150 debug("%s: sent", __func__); 151 } 152 153 static void 154 userauth_banner(void) 155 { 156 char *banner = NULL; 157 158 if (options.banner == NULL || (datafellows & SSH_BUG_BANNER) != 0) 159 return; 160 161 if ((banner = PRIVSEP(auth2_read_banner())) == NULL) 162 goto done; 163 userauth_send_banner(banner); 164 165 done: 166 free(banner); 167 } 168 169 /* 170 * loop until authctxt->success == TRUE 171 */ 172 void 173 do_authentication2(Authctxt *authctxt) 174 { 175 struct ssh *ssh = active_state; /* XXX */ 176 ssh->authctxt = authctxt; /* XXX move to caller */ 177 ssh_dispatch_init(ssh, &dispatch_protocol_error); 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 /*ARGSUSED*/ 184 static int 185 input_service_request(int type, u_int32_t seq, struct ssh *ssh) 186 { 187 Authctxt *authctxt = ssh->authctxt; 188 u_int len; 189 int acceptit = 0; 190 char *service = packet_get_cstring(&len); 191 packet_check_eom(); 192 193 if (authctxt == NULL) 194 fatal("input_service_request: no authctxt"); 195 196 if (strcmp(service, "ssh-userauth") == 0) { 197 if (!authctxt->success) { 198 acceptit = 1; 199 /* now we can handle user-auth requests */ 200 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, &input_userauth_request); 201 } 202 } 203 /* XXX all other service requests are denied */ 204 205 if (acceptit) { 206 packet_start(SSH2_MSG_SERVICE_ACCEPT); 207 packet_put_cstring(service); 208 packet_send(); 209 packet_write_wait(); 210 } else { 211 debug("bad service request %s", service); 212 packet_disconnect("bad service request %s", service); 213 } 214 free(service); 215 return 0; 216 } 217 218 /*ARGSUSED*/ 219 static int 220 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 221 { 222 Authctxt *authctxt = ssh->authctxt; 223 Authmethod *m = NULL; 224 char *user, *service, *method, *style = NULL; 225 int authenticated = 0; 226 #ifdef HAVE_LOGIN_CAP 227 login_cap_t *lc; 228 const char *from_host, *from_ip; 229 #endif 230 231 if (authctxt == NULL) 232 fatal("input_userauth_request: no authctxt"); 233 234 user = packet_get_cstring(NULL); 235 service = packet_get_cstring(NULL); 236 method = packet_get_cstring(NULL); 237 debug("userauth-request for user %s service %s method %s", user, service, method); 238 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 239 240 if ((style = strchr(user, ':')) != NULL) 241 *style++ = 0; 242 243 if (authctxt->attempt++ == 0) { 244 /* setup auth context */ 245 authctxt->pw = PRIVSEP(getpwnamallow(user)); 246 authctxt->user = xstrdup(user); 247 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 248 authctxt->valid = 1; 249 debug2("%s: setting up authctxt for %s", 250 __func__, user); 251 } else { 252 /* Invalid user, fake password information */ 253 authctxt->pw = fakepw(); 254 #ifdef SSH_AUDIT_EVENTS 255 PRIVSEP(audit_event(SSH_INVALID_USER)); 256 #endif 257 } 258 #ifdef USE_PAM 259 if (options.use_pam) 260 PRIVSEP(start_pam(authctxt)); 261 #endif 262 ssh_packet_set_log_preamble(ssh, "%suser %s", 263 authctxt->valid ? "authenticating " : "invalid ", user); 264 setproctitle("%s%s", authctxt->valid ? user : "unknown", 265 use_privsep ? " [net]" : ""); 266 authctxt->service = xstrdup(service); 267 authctxt->style = style ? xstrdup(style) : NULL; 268 if (use_privsep) 269 mm_inform_authserv(service, style); 270 userauth_banner(); 271 if (auth2_setup_methods_lists(authctxt) != 0) 272 packet_disconnect("no authentication methods enabled"); 273 } else if (strcmp(user, authctxt->user) != 0 || 274 strcmp(service, authctxt->service) != 0) { 275 packet_disconnect("Change of username or service not allowed: " 276 "(%s,%s) -> (%s,%s)", 277 authctxt->user, authctxt->service, user, service); 278 } 279 280 #ifdef HAVE_LOGIN_CAP 281 if (authctxt->pw != NULL && 282 (lc = login_getpwclass(authctxt->pw)) != NULL) { 283 logit("user %s login class %s", authctxt->pw->pw_name, 284 authctxt->pw->pw_class); 285 from_host = auth_get_canonical_hostname(ssh, options.use_dns); 286 from_ip = ssh_remote_ipaddr(ssh); 287 if (!auth_hostok(lc, from_host, from_ip)) { 288 logit("Denied connection for %.200s from %.200s [%.200s].", 289 authctxt->pw->pw_name, from_host, from_ip); 290 packet_disconnect("Sorry, you are not allowed to connect."); 291 } 292 if (!auth_timeok(lc, time(NULL))) { 293 logit("LOGIN %.200s REFUSED (TIME) FROM %.200s", 294 authctxt->pw->pw_name, from_host); 295 packet_disconnect("Logins not available right now."); 296 } 297 login_close(lc); 298 } 299 #endif /* HAVE_LOGIN_CAP */ 300 301 /* reset state */ 302 auth2_challenge_stop(ssh); 303 304 #ifdef GSSAPI 305 /* XXX move to auth2_gssapi_stop() */ 306 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 307 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 308 #endif 309 310 auth2_authctxt_reset_info(authctxt); 311 authctxt->postponed = 0; 312 authctxt->server_caused_failure = 0; 313 314 /* try to authenticate user */ 315 m = authmethod_lookup(authctxt, method); 316 if (m != NULL && authctxt->failures < options.max_authtries) { 317 debug2("input_userauth_request: try method %s", method); 318 authenticated = m->userauth(ssh); 319 } 320 userauth_finish(ssh, authenticated, method, NULL); 321 322 free(service); 323 free(user); 324 free(method); 325 return 0; 326 } 327 328 void 329 userauth_finish(struct ssh *ssh, int authenticated, const char *method, 330 const char *submethod) 331 { 332 Authctxt *authctxt = ssh->authctxt; 333 char *methods; 334 int partial = 0; 335 336 if (!authctxt->valid && authenticated) 337 fatal("INTERNAL ERROR: authenticated invalid user %s", 338 authctxt->user); 339 if (authenticated && authctxt->postponed) 340 fatal("INTERNAL ERROR: authenticated and postponed"); 341 342 /* Special handling for root */ 343 if (authenticated && authctxt->pw->pw_uid == 0 && 344 !auth_root_allowed(method)) { 345 authenticated = 0; 346 #ifdef SSH_AUDIT_EVENTS 347 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED)); 348 #endif 349 } 350 351 if (authenticated && options.num_auth_methods != 0) { 352 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 353 authenticated = 0; 354 partial = 1; 355 } 356 } 357 358 /* Log before sending the reply */ 359 auth_log(authctxt, authenticated, partial, method, submethod); 360 361 /* Update information exposed to session */ 362 if (authenticated || partial) 363 auth2_update_session_info(authctxt, method, submethod); 364 365 if (authctxt->postponed) 366 return; 367 368 #ifdef USE_PAM 369 if (options.use_pam && authenticated) { 370 if (!PRIVSEP(do_pam_account())) { 371 /* if PAM returned a message, send it to the user */ 372 if (buffer_len(&loginmsg) > 0) { 373 buffer_append(&loginmsg, "\0", 1); 374 userauth_send_banner(buffer_ptr(&loginmsg)); 375 packet_write_wait(); 376 } 377 fatal("Access denied for user %s by PAM account " 378 "configuration", authctxt->user); 379 } 380 } 381 #endif 382 383 #ifdef _UNICOS 384 if (authenticated && cray_access_denied(authctxt->user)) { 385 authenticated = 0; 386 fatal("Access denied for user %s.", authctxt->user); 387 } 388 #endif /* _UNICOS */ 389 390 if (authenticated == 1) { 391 /* turn off userauth */ 392 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); 393 packet_start(SSH2_MSG_USERAUTH_SUCCESS); 394 packet_send(); 395 packet_write_wait(); 396 /* now we can break out */ 397 authctxt->success = 1; 398 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 399 } else { 400 401 /* Allow initial try of "none" auth without failure penalty */ 402 if (!partial && !authctxt->server_caused_failure && 403 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) { 404 authctxt->failures++; 405 BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL, "ssh"); 406 } 407 if (authctxt->failures >= options.max_authtries) { 408 #ifdef SSH_AUDIT_EVENTS 409 PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES)); 410 #endif 411 auth_maxtries_exceeded(authctxt); 412 } 413 methods = authmethods_get(authctxt); 414 debug3("%s: failure partial=%d next methods=\"%s\"", __func__, 415 partial, methods); 416 packet_start(SSH2_MSG_USERAUTH_FAILURE); 417 packet_put_cstring(methods); 418 packet_put_char(partial); 419 packet_send(); 420 packet_write_wait(); 421 free(methods); 422 } 423 } 424 425 /* 426 * Checks whether method is allowed by at least one AuthenticationMethods 427 * methods list. Returns 1 if allowed, or no methods lists configured. 428 * 0 otherwise. 429 */ 430 int 431 auth2_method_allowed(Authctxt *authctxt, const char *method, 432 const char *submethod) 433 { 434 u_int i; 435 436 /* 437 * NB. authctxt->num_auth_methods might be zero as a result of 438 * auth2_setup_methods_lists(), so check the configuration. 439 */ 440 if (options.num_auth_methods == 0) 441 return 1; 442 for (i = 0; i < authctxt->num_auth_methods; i++) { 443 if (list_starts_with(authctxt->auth_methods[i], method, 444 submethod) != MATCH_NONE) 445 return 1; 446 } 447 return 0; 448 } 449 450 static char * 451 authmethods_get(Authctxt *authctxt) 452 { 453 Buffer b; 454 char *list; 455 u_int i; 456 457 buffer_init(&b); 458 for (i = 0; authmethods[i] != NULL; i++) { 459 if (strcmp(authmethods[i]->name, "none") == 0) 460 continue; 461 if (authmethods[i]->enabled == NULL || 462 *(authmethods[i]->enabled) == 0) 463 continue; 464 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 465 NULL)) 466 continue; 467 if (buffer_len(&b) > 0) 468 buffer_append(&b, ",", 1); 469 buffer_append(&b, authmethods[i]->name, 470 strlen(authmethods[i]->name)); 471 } 472 if ((list = sshbuf_dup_string(&b)) == NULL) 473 fatal("%s: sshbuf_dup_string failed", __func__); 474 buffer_free(&b); 475 return list; 476 } 477 478 static Authmethod * 479 authmethod_lookup(Authctxt *authctxt, const char *name) 480 { 481 int i; 482 483 if (name != NULL) 484 for (i = 0; authmethods[i] != NULL; i++) 485 if (authmethods[i]->enabled != NULL && 486 *(authmethods[i]->enabled) != 0 && 487 strcmp(name, authmethods[i]->name) == 0 && 488 auth2_method_allowed(authctxt, 489 authmethods[i]->name, NULL)) 490 return authmethods[i]; 491 debug2("Unrecognized authentication method name: %s", 492 name ? name : "NULL"); 493 return NULL; 494 } 495 496 /* 497 * Check a comma-separated list of methods for validity. Is need_enable is 498 * non-zero, then also require that the methods are enabled. 499 * Returns 0 on success or -1 if the methods list is invalid. 500 */ 501 int 502 auth2_methods_valid(const char *_methods, int need_enable) 503 { 504 char *methods, *omethods, *method, *p; 505 u_int i, found; 506 int ret = -1; 507 508 if (*_methods == '\0') { 509 error("empty authentication method list"); 510 return -1; 511 } 512 omethods = methods = xstrdup(_methods); 513 while ((method = strsep(&methods, ",")) != NULL) { 514 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 515 if ((p = strchr(method, ':')) != NULL) 516 *p = '\0'; 517 if (strcmp(method, authmethods[i]->name) != 0) 518 continue; 519 if (need_enable) { 520 if (authmethods[i]->enabled == NULL || 521 *(authmethods[i]->enabled) == 0) { 522 error("Disabled method \"%s\" in " 523 "AuthenticationMethods list \"%s\"", 524 method, _methods); 525 goto out; 526 } 527 } 528 found = 1; 529 break; 530 } 531 if (!found) { 532 error("Unknown authentication method \"%s\" in list", 533 method); 534 goto out; 535 } 536 } 537 ret = 0; 538 out: 539 free(omethods); 540 return ret; 541 } 542 543 /* 544 * Prune the AuthenticationMethods supplied in the configuration, removing 545 * any methods lists that include disabled methods. Note that this might 546 * leave authctxt->num_auth_methods == 0, even when multiple required auth 547 * has been requested. For this reason, all tests for whether multiple is 548 * enabled should consult options.num_auth_methods directly. 549 */ 550 int 551 auth2_setup_methods_lists(Authctxt *authctxt) 552 { 553 u_int i; 554 555 if (options.num_auth_methods == 0) 556 return 0; 557 debug3("%s: checking methods", __func__); 558 authctxt->auth_methods = xcalloc(options.num_auth_methods, 559 sizeof(*authctxt->auth_methods)); 560 authctxt->num_auth_methods = 0; 561 for (i = 0; i < options.num_auth_methods; i++) { 562 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 563 logit("Authentication methods list \"%s\" contains " 564 "disabled method, skipping", 565 options.auth_methods[i]); 566 continue; 567 } 568 debug("authentication methods list %d: %s", 569 authctxt->num_auth_methods, options.auth_methods[i]); 570 authctxt->auth_methods[authctxt->num_auth_methods++] = 571 xstrdup(options.auth_methods[i]); 572 } 573 if (authctxt->num_auth_methods == 0) { 574 error("No AuthenticationMethods left after eliminating " 575 "disabled methods"); 576 return -1; 577 } 578 return 0; 579 } 580 581 static int 582 list_starts_with(const char *methods, const char *method, 583 const char *submethod) 584 { 585 size_t l = strlen(method); 586 int match; 587 const char *p; 588 589 if (strncmp(methods, method, l) != 0) 590 return MATCH_NONE; 591 p = methods + l; 592 match = MATCH_METHOD; 593 if (*p == ':') { 594 if (!submethod) 595 return MATCH_PARTIAL; 596 l = strlen(submethod); 597 p += 1; 598 if (strncmp(submethod, p, l)) 599 return MATCH_NONE; 600 p += l; 601 match = MATCH_BOTH; 602 } 603 if (*p != ',' && *p != '\0') 604 return MATCH_NONE; 605 return match; 606 } 607 608 /* 609 * Remove method from the start of a comma-separated list of methods. 610 * Returns 0 if the list of methods did not start with that method or 1 611 * if it did. 612 */ 613 static int 614 remove_method(char **methods, const char *method, const char *submethod) 615 { 616 char *omethods = *methods, *p; 617 size_t l = strlen(method); 618 int match; 619 620 match = list_starts_with(omethods, method, submethod); 621 if (match != MATCH_METHOD && match != MATCH_BOTH) 622 return 0; 623 p = omethods + l; 624 if (submethod && match == MATCH_BOTH) 625 p += 1 + strlen(submethod); /* include colon */ 626 if (*p == ',') 627 p++; 628 *methods = xstrdup(p); 629 free(omethods); 630 return 1; 631 } 632 633 /* 634 * Called after successful authentication. Will remove the successful method 635 * from the start of each list in which it occurs. If it was the last method 636 * in any list, then authentication is deemed successful. 637 * Returns 1 if the method completed any authentication list or 0 otherwise. 638 */ 639 int 640 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 641 const char *submethod) 642 { 643 u_int i, found = 0; 644 645 debug3("%s: updating methods list after \"%s\"", __func__, method); 646 for (i = 0; i < authctxt->num_auth_methods; i++) { 647 if (!remove_method(&(authctxt->auth_methods[i]), method, 648 submethod)) 649 continue; 650 found = 1; 651 if (*authctxt->auth_methods[i] == '\0') { 652 debug2("authentication methods list %d complete", i); 653 return 1; 654 } 655 debug3("authentication methods list %d remaining: \"%s\"", 656 i, authctxt->auth_methods[i]); 657 } 658 /* This should not happen, but would be bad if it did */ 659 if (!found) 660 fatal("%s: method not in AuthenticationMethods", __func__); 661 return 0; 662 } 663 664 /* Reset method-specific information */ 665 void auth2_authctxt_reset_info(Authctxt *authctxt) 666 { 667 sshkey_free(authctxt->auth_method_key); 668 free(authctxt->auth_method_info); 669 authctxt->auth_method_key = NULL; 670 authctxt->auth_method_info = NULL; 671 } 672 673 /* Record auth method-specific information for logs */ 674 void 675 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 676 { 677 va_list ap; 678 int i; 679 680 free(authctxt->auth_method_info); 681 authctxt->auth_method_info = NULL; 682 683 va_start(ap, fmt); 684 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 685 va_end(ap); 686 687 if (i < 0 || authctxt->auth_method_info == NULL) 688 fatal("%s: vasprintf failed", __func__); 689 } 690 691 /* 692 * Records a public key used in authentication. This is used for logging 693 * and to ensure that the same key is not subsequently accepted again for 694 * multiple authentication. 695 */ 696 void 697 auth2_record_key(Authctxt *authctxt, int authenticated, 698 const struct sshkey *key) 699 { 700 struct sshkey **tmp, *dup; 701 int r; 702 703 if ((r = sshkey_demote(key, &dup)) != 0) 704 fatal("%s: copy key: %s", __func__, ssh_err(r)); 705 sshkey_free(authctxt->auth_method_key); 706 authctxt->auth_method_key = dup; 707 708 if (!authenticated) 709 return; 710 711 /* If authenticated, make sure we don't accept this key again */ 712 if ((r = sshkey_demote(key, &dup)) != 0) 713 fatal("%s: copy key: %s", __func__, ssh_err(r)); 714 if (authctxt->nprev_keys >= INT_MAX || 715 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 716 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 717 fatal("%s: reallocarray failed", __func__); 718 authctxt->prev_keys = tmp; 719 authctxt->prev_keys[authctxt->nprev_keys] = dup; 720 authctxt->nprev_keys++; 721 722 } 723 724 /* Checks whether a key has already been previously used for authentication */ 725 int 726 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 727 { 728 u_int i; 729 char *fp; 730 731 for (i = 0; i < authctxt->nprev_keys; i++) { 732 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 733 fp = sshkey_fingerprint(authctxt->prev_keys[i], 734 options.fingerprint_hash, SSH_FP_DEFAULT); 735 debug3("%s: key already used: %s %s", __func__, 736 sshkey_type(authctxt->prev_keys[i]), 737 fp == NULL ? "UNKNOWN" : fp); 738 free(fp); 739 return 1; 740 } 741 } 742 return 0; 743 } 744 745 /* 746 * Updates authctxt->session_info with details of authentication. Should be 747 * whenever an authentication method succeeds. 748 */ 749 void 750 auth2_update_session_info(Authctxt *authctxt, const char *method, 751 const char *submethod) 752 { 753 int r; 754 755 if (authctxt->session_info == NULL) { 756 if ((authctxt->session_info = sshbuf_new()) == NULL) 757 fatal("%s: sshbuf_new", __func__); 758 } 759 760 /* Append method[/submethod] */ 761 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 762 method, submethod == NULL ? "" : "/", 763 submethod == NULL ? "" : submethod)) != 0) 764 fatal("%s: append method: %s", __func__, ssh_err(r)); 765 766 /* Append key if present */ 767 if (authctxt->auth_method_key != NULL) { 768 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 769 (r = sshkey_format_text(authctxt->auth_method_key, 770 authctxt->session_info)) != 0) 771 fatal("%s: append key: %s", __func__, ssh_err(r)); 772 } 773 774 if (authctxt->auth_method_info != NULL) { 775 /* Ensure no ambiguity here */ 776 if (strchr(authctxt->auth_method_info, '\n') != NULL) 777 fatal("%s: auth_method_info contains \\n", __func__); 778 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 779 (r = sshbuf_putf(authctxt->session_info, "%s", 780 authctxt->auth_method_info)) != 0) { 781 fatal("%s: append method info: %s", 782 __func__, ssh_err(r)); 783 } 784 } 785 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 786 fatal("%s: append: %s", __func__, ssh_err(r)); 787 } 788 789