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 /* reset state */ 317 auth2_challenge_stop(ssh); 318 319 #ifdef GSSAPI 320 /* XXX move to auth2_gssapi_stop() */ 321 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 322 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 323 #endif 324 325 auth2_authctxt_reset_info(authctxt); 326 authctxt->postponed = 0; 327 authctxt->server_caused_failure = 0; 328 329 /* try to authenticate user */ 330 m = authmethod_lookup(authctxt, method); 331 if (m != NULL && authctxt->failures < options.max_authtries) { 332 debug2("input_userauth_request: try method %s", method); 333 authenticated = m->userauth(ssh); 334 } 335 if (!authctxt->authenticated) 336 ensure_minimum_time_since(tstart, 337 user_specific_delay(authctxt->user)); 338 userauth_finish(ssh, authenticated, method, NULL); 339 340 free(service); 341 free(user); 342 free(method); 343 return 0; 344 } 345 346 void 347 userauth_finish(struct ssh *ssh, int authenticated, const char *method, 348 const char *submethod) 349 { 350 Authctxt *authctxt = ssh->authctxt; 351 char *methods; 352 int partial = 0; 353 354 if (!authctxt->valid && authenticated) 355 fatal("INTERNAL ERROR: authenticated invalid user %s", 356 authctxt->user); 357 if (authenticated && authctxt->postponed) 358 fatal("INTERNAL ERROR: authenticated and postponed"); 359 360 /* Special handling for root */ 361 if (authenticated && authctxt->pw->pw_uid == 0 && 362 !auth_root_allowed(ssh, method)) { 363 authenticated = 0; 364 #ifdef SSH_AUDIT_EVENTS 365 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED)); 366 #endif 367 } 368 369 if (authenticated && options.num_auth_methods != 0) { 370 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 371 authenticated = 0; 372 partial = 1; 373 } 374 } 375 376 /* Log before sending the reply */ 377 auth_log(authctxt, authenticated, partial, method, submethod); 378 379 /* Update information exposed to session */ 380 if (authenticated || partial) 381 auth2_update_session_info(authctxt, method, submethod); 382 383 if (authctxt->postponed) 384 return; 385 386 #ifdef USE_PAM 387 if (options.use_pam && authenticated) { 388 int r; 389 390 if (!PRIVSEP(do_pam_account())) { 391 /* if PAM returned a message, send it to the user */ 392 if (sshbuf_len(loginmsg) > 0) { 393 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0) 394 fatal("%s: buffer error: %s", 395 __func__, ssh_err(r)); 396 userauth_send_banner(sshbuf_ptr(loginmsg)); 397 packet_write_wait(); 398 } 399 fatal("Access denied for user %s by PAM account " 400 "configuration", authctxt->user); 401 } 402 } 403 #endif 404 405 if (authenticated == 1) { 406 /* turn off userauth */ 407 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, &dispatch_protocol_ignore); 408 packet_start(SSH2_MSG_USERAUTH_SUCCESS); 409 packet_send(); 410 packet_write_wait(); 411 /* now we can break out */ 412 authctxt->success = 1; 413 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 414 } else { 415 /* Allow initial try of "none" auth without failure penalty */ 416 if (!partial && !authctxt->server_caused_failure && 417 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) { 418 authctxt->failures++; 419 BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL, "ssh"); 420 } 421 if (authctxt->failures >= options.max_authtries) { 422 #ifdef SSH_AUDIT_EVENTS 423 PRIVSEP(audit_event(SSH_LOGIN_EXCEED_MAXTRIES)); 424 #endif 425 auth_maxtries_exceeded(authctxt); 426 } 427 methods = authmethods_get(authctxt); 428 debug3("%s: failure partial=%d next methods=\"%s\"", __func__, 429 partial, methods); 430 packet_start(SSH2_MSG_USERAUTH_FAILURE); 431 packet_put_cstring(methods); 432 packet_put_char(partial); 433 packet_send(); 434 packet_write_wait(); 435 free(methods); 436 } 437 } 438 439 /* 440 * Checks whether method is allowed by at least one AuthenticationMethods 441 * methods list. Returns 1 if allowed, or no methods lists configured. 442 * 0 otherwise. 443 */ 444 int 445 auth2_method_allowed(Authctxt *authctxt, const char *method, 446 const char *submethod) 447 { 448 u_int i; 449 450 /* 451 * NB. authctxt->num_auth_methods might be zero as a result of 452 * auth2_setup_methods_lists(), so check the configuration. 453 */ 454 if (options.num_auth_methods == 0) 455 return 1; 456 for (i = 0; i < authctxt->num_auth_methods; i++) { 457 if (list_starts_with(authctxt->auth_methods[i], method, 458 submethod) != MATCH_NONE) 459 return 1; 460 } 461 return 0; 462 } 463 464 static char * 465 authmethods_get(Authctxt *authctxt) 466 { 467 struct sshbuf *b; 468 char *list; 469 int i, r; 470 471 if ((b = sshbuf_new()) == NULL) 472 fatal("%s: sshbuf_new failed", __func__); 473 for (i = 0; authmethods[i] != NULL; i++) { 474 if (strcmp(authmethods[i]->name, "none") == 0) 475 continue; 476 if (authmethods[i]->enabled == NULL || 477 *(authmethods[i]->enabled) == 0) 478 continue; 479 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 480 NULL)) 481 continue; 482 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 483 authmethods[i]->name)) != 0) 484 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 485 } 486 if ((list = sshbuf_dup_string(b)) == NULL) 487 fatal("%s: sshbuf_dup_string failed", __func__); 488 sshbuf_free(b); 489 return list; 490 } 491 492 static Authmethod * 493 authmethod_lookup(Authctxt *authctxt, const char *name) 494 { 495 int i; 496 497 if (name != NULL) 498 for (i = 0; authmethods[i] != NULL; i++) 499 if (authmethods[i]->enabled != NULL && 500 *(authmethods[i]->enabled) != 0 && 501 strcmp(name, authmethods[i]->name) == 0 && 502 auth2_method_allowed(authctxt, 503 authmethods[i]->name, NULL)) 504 return authmethods[i]; 505 debug2("Unrecognized authentication method name: %s", 506 name ? name : "NULL"); 507 return NULL; 508 } 509 510 /* 511 * Check a comma-separated list of methods for validity. Is need_enable is 512 * non-zero, then also require that the methods are enabled. 513 * Returns 0 on success or -1 if the methods list is invalid. 514 */ 515 int 516 auth2_methods_valid(const char *_methods, int need_enable) 517 { 518 char *methods, *omethods, *method, *p; 519 u_int i, found; 520 int ret = -1; 521 522 if (*_methods == '\0') { 523 error("empty authentication method list"); 524 return -1; 525 } 526 omethods = methods = xstrdup(_methods); 527 while ((method = strsep(&methods, ",")) != NULL) { 528 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 529 if ((p = strchr(method, ':')) != NULL) 530 *p = '\0'; 531 if (strcmp(method, authmethods[i]->name) != 0) 532 continue; 533 if (need_enable) { 534 if (authmethods[i]->enabled == NULL || 535 *(authmethods[i]->enabled) == 0) { 536 error("Disabled method \"%s\" in " 537 "AuthenticationMethods list \"%s\"", 538 method, _methods); 539 goto out; 540 } 541 } 542 found = 1; 543 break; 544 } 545 if (!found) { 546 error("Unknown authentication method \"%s\" in list", 547 method); 548 goto out; 549 } 550 } 551 ret = 0; 552 out: 553 free(omethods); 554 return ret; 555 } 556 557 /* 558 * Prune the AuthenticationMethods supplied in the configuration, removing 559 * any methods lists that include disabled methods. Note that this might 560 * leave authctxt->num_auth_methods == 0, even when multiple required auth 561 * has been requested. For this reason, all tests for whether multiple is 562 * enabled should consult options.num_auth_methods directly. 563 */ 564 int 565 auth2_setup_methods_lists(Authctxt *authctxt) 566 { 567 u_int i; 568 569 if (options.num_auth_methods == 0) 570 return 0; 571 debug3("%s: checking methods", __func__); 572 authctxt->auth_methods = xcalloc(options.num_auth_methods, 573 sizeof(*authctxt->auth_methods)); 574 authctxt->num_auth_methods = 0; 575 for (i = 0; i < options.num_auth_methods; i++) { 576 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 577 logit("Authentication methods list \"%s\" contains " 578 "disabled method, skipping", 579 options.auth_methods[i]); 580 continue; 581 } 582 debug("authentication methods list %d: %s", 583 authctxt->num_auth_methods, options.auth_methods[i]); 584 authctxt->auth_methods[authctxt->num_auth_methods++] = 585 xstrdup(options.auth_methods[i]); 586 } 587 if (authctxt->num_auth_methods == 0) { 588 error("No AuthenticationMethods left after eliminating " 589 "disabled methods"); 590 return -1; 591 } 592 return 0; 593 } 594 595 static int 596 list_starts_with(const char *methods, const char *method, 597 const char *submethod) 598 { 599 size_t l = strlen(method); 600 int match; 601 const char *p; 602 603 if (strncmp(methods, method, l) != 0) 604 return MATCH_NONE; 605 p = methods + l; 606 match = MATCH_METHOD; 607 if (*p == ':') { 608 if (!submethod) 609 return MATCH_PARTIAL; 610 l = strlen(submethod); 611 p += 1; 612 if (strncmp(submethod, p, l)) 613 return MATCH_NONE; 614 p += l; 615 match = MATCH_BOTH; 616 } 617 if (*p != ',' && *p != '\0') 618 return MATCH_NONE; 619 return match; 620 } 621 622 /* 623 * Remove method from the start of a comma-separated list of methods. 624 * Returns 0 if the list of methods did not start with that method or 1 625 * if it did. 626 */ 627 static int 628 remove_method(char **methods, const char *method, const char *submethod) 629 { 630 char *omethods = *methods, *p; 631 size_t l = strlen(method); 632 int match; 633 634 match = list_starts_with(omethods, method, submethod); 635 if (match != MATCH_METHOD && match != MATCH_BOTH) 636 return 0; 637 p = omethods + l; 638 if (submethod && match == MATCH_BOTH) 639 p += 1 + strlen(submethod); /* include colon */ 640 if (*p == ',') 641 p++; 642 *methods = xstrdup(p); 643 free(omethods); 644 return 1; 645 } 646 647 /* 648 * Called after successful authentication. Will remove the successful method 649 * from the start of each list in which it occurs. If it was the last method 650 * in any list, then authentication is deemed successful. 651 * Returns 1 if the method completed any authentication list or 0 otherwise. 652 */ 653 int 654 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 655 const char *submethod) 656 { 657 u_int i, found = 0; 658 659 debug3("%s: updating methods list after \"%s\"", __func__, method); 660 for (i = 0; i < authctxt->num_auth_methods; i++) { 661 if (!remove_method(&(authctxt->auth_methods[i]), method, 662 submethod)) 663 continue; 664 found = 1; 665 if (*authctxt->auth_methods[i] == '\0') { 666 debug2("authentication methods list %d complete", i); 667 return 1; 668 } 669 debug3("authentication methods list %d remaining: \"%s\"", 670 i, authctxt->auth_methods[i]); 671 } 672 /* This should not happen, but would be bad if it did */ 673 if (!found) 674 fatal("%s: method not in AuthenticationMethods", __func__); 675 return 0; 676 } 677 678 /* Reset method-specific information */ 679 void auth2_authctxt_reset_info(Authctxt *authctxt) 680 { 681 sshkey_free(authctxt->auth_method_key); 682 free(authctxt->auth_method_info); 683 authctxt->auth_method_key = NULL; 684 authctxt->auth_method_info = NULL; 685 } 686 687 /* Record auth method-specific information for logs */ 688 void 689 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 690 { 691 va_list ap; 692 int i; 693 694 free(authctxt->auth_method_info); 695 authctxt->auth_method_info = NULL; 696 697 va_start(ap, fmt); 698 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 699 va_end(ap); 700 701 if (i < 0 || authctxt->auth_method_info == NULL) 702 fatal("%s: vasprintf failed", __func__); 703 } 704 705 /* 706 * Records a public key used in authentication. This is used for logging 707 * and to ensure that the same key is not subsequently accepted again for 708 * multiple authentication. 709 */ 710 void 711 auth2_record_key(Authctxt *authctxt, int authenticated, 712 const struct sshkey *key) 713 { 714 struct sshkey **tmp, *dup; 715 int r; 716 717 if ((r = sshkey_from_private(key, &dup)) != 0) 718 fatal("%s: copy key: %s", __func__, ssh_err(r)); 719 sshkey_free(authctxt->auth_method_key); 720 authctxt->auth_method_key = dup; 721 722 if (!authenticated) 723 return; 724 725 /* If authenticated, make sure we don't accept this key again */ 726 if ((r = sshkey_from_private(key, &dup)) != 0) 727 fatal("%s: copy key: %s", __func__, ssh_err(r)); 728 if (authctxt->nprev_keys >= INT_MAX || 729 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 730 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 731 fatal("%s: reallocarray failed", __func__); 732 authctxt->prev_keys = tmp; 733 authctxt->prev_keys[authctxt->nprev_keys] = dup; 734 authctxt->nprev_keys++; 735 736 } 737 738 /* Checks whether a key has already been previously used for authentication */ 739 int 740 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 741 { 742 u_int i; 743 char *fp; 744 745 for (i = 0; i < authctxt->nprev_keys; i++) { 746 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 747 fp = sshkey_fingerprint(authctxt->prev_keys[i], 748 options.fingerprint_hash, SSH_FP_DEFAULT); 749 debug3("%s: key already used: %s %s", __func__, 750 sshkey_type(authctxt->prev_keys[i]), 751 fp == NULL ? "UNKNOWN" : fp); 752 free(fp); 753 return 1; 754 } 755 } 756 return 0; 757 } 758 759 /* 760 * Updates authctxt->session_info with details of authentication. Should be 761 * whenever an authentication method succeeds. 762 */ 763 void 764 auth2_update_session_info(Authctxt *authctxt, const char *method, 765 const char *submethod) 766 { 767 int r; 768 769 if (authctxt->session_info == NULL) { 770 if ((authctxt->session_info = sshbuf_new()) == NULL) 771 fatal("%s: sshbuf_new", __func__); 772 } 773 774 /* Append method[/submethod] */ 775 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 776 method, submethod == NULL ? "" : "/", 777 submethod == NULL ? "" : submethod)) != 0) 778 fatal("%s: append method: %s", __func__, ssh_err(r)); 779 780 /* Append key if present */ 781 if (authctxt->auth_method_key != NULL) { 782 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 783 (r = sshkey_format_text(authctxt->auth_method_key, 784 authctxt->session_info)) != 0) 785 fatal("%s: append key: %s", __func__, ssh_err(r)); 786 } 787 788 if (authctxt->auth_method_info != NULL) { 789 /* Ensure no ambiguity here */ 790 if (strchr(authctxt->auth_method_info, '\n') != NULL) 791 fatal("%s: auth_method_info contains \\n", __func__); 792 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 793 (r = sshbuf_putf(authctxt->session_info, "%s", 794 authctxt->auth_method_info)) != 0) { 795 fatal("%s: append method info: %s", 796 __func__, ssh_err(r)); 797 } 798 } 799 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 800 fatal("%s: append: %s", __func__, ssh_err(r)); 801 } 802 803