1 /* $OpenBSD: auth2.c,v 1.158 2020/03/06 18:16:21 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 28 #include <sys/types.h> 29 #include <sys/stat.h> 30 #include <sys/uio.h> 31 32 #include <fcntl.h> 33 #include <limits.h> 34 #include <pwd.h> 35 #include <stdarg.h> 36 #include <string.h> 37 #include <unistd.h> 38 #include <time.h> 39 40 #include "stdlib.h" 41 #include "atomicio.h" 42 #include "xmalloc.h" 43 #include "ssh2.h" 44 #include "packet.h" 45 #include "log.h" 46 #include "sshbuf.h" 47 #include "misc.h" 48 #include "servconf.h" 49 #include "compat.h" 50 #include "sshkey.h" 51 #include "hostfile.h" 52 #include "auth.h" 53 #include "dispatch.h" 54 #include "pathnames.h" 55 #include "ssherr.h" 56 #ifdef GSSAPI 57 #include "ssh-gss.h" 58 #endif 59 #include "monitor_wrap.h" 60 #include "digest.h" 61 62 /* import */ 63 extern ServerOptions options; 64 extern u_char *session_id2; 65 extern u_int session_id2_len; 66 extern struct sshbuf *loginmsg; 67 68 /* methods */ 69 70 extern Authmethod method_none; 71 extern Authmethod method_pubkey; 72 extern Authmethod method_passwd; 73 extern Authmethod method_kbdint; 74 extern Authmethod method_hostbased; 75 #ifdef GSSAPI 76 extern Authmethod method_gssapi; 77 #endif 78 79 Authmethod *authmethods[] = { 80 &method_none, 81 &method_pubkey, 82 #ifdef GSSAPI 83 &method_gssapi, 84 #endif 85 &method_passwd, 86 &method_kbdint, 87 &method_hostbased, 88 NULL 89 }; 90 91 /* protocol */ 92 93 static int input_service_request(int, u_int32_t, struct ssh *); 94 static int input_userauth_request(int, u_int32_t, struct ssh *); 95 96 /* helper */ 97 static Authmethod *authmethod_lookup(Authctxt *, const char *); 98 static char *authmethods_get(Authctxt *authctxt); 99 100 #define MATCH_NONE 0 /* method or submethod mismatch */ 101 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 102 #define MATCH_BOTH 2 /* method and submethod match */ 103 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 104 static int list_starts_with(const char *, const char *, const char *); 105 106 char * 107 auth2_read_banner(void) 108 { 109 struct stat st; 110 char *banner = NULL; 111 size_t len, n; 112 int fd; 113 114 if ((fd = open(options.banner, O_RDONLY)) == -1) 115 return (NULL); 116 if (fstat(fd, &st) == -1) { 117 close(fd); 118 return (NULL); 119 } 120 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 121 close(fd); 122 return (NULL); 123 } 124 125 len = (size_t)st.st_size; /* truncate */ 126 banner = xmalloc(len + 1); 127 n = atomicio(read, fd, banner, len); 128 close(fd); 129 130 if (n != len) { 131 free(banner); 132 return (NULL); 133 } 134 banner[n] = '\0'; 135 136 return (banner); 137 } 138 139 static void 140 userauth_send_banner(struct ssh *ssh, const char *msg) 141 { 142 int r; 143 144 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 || 145 (r = sshpkt_put_cstring(ssh, msg)) != 0 || 146 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */ 147 (r = sshpkt_send(ssh)) != 0) 148 fatal("%s: %s", __func__, ssh_err(r)); 149 debug("%s: sent", __func__); 150 } 151 152 static void 153 userauth_banner(struct ssh *ssh) 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(ssh, banner); 163 164 done: 165 free(banner); 166 } 167 168 /* 169 * loop until authctxt->success == TRUE 170 */ 171 void 172 do_authentication2(struct ssh *ssh) 173 { 174 Authctxt *authctxt = ssh->authctxt; 175 176 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 char *service = NULL; 188 int r, acceptit = 0; 189 190 if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 191 (r = sshpkt_get_end(ssh)) != 0) 192 goto out; 193 194 if (authctxt == NULL) 195 fatal("input_service_request: no authctxt"); 196 197 if (strcmp(service, "ssh-userauth") == 0) { 198 if (!authctxt->success) { 199 acceptit = 1; 200 /* now we can handle user-auth requests */ 201 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 202 &input_userauth_request); 203 } 204 } 205 /* XXX all other service requests are denied */ 206 207 if (acceptit) { 208 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 || 209 (r = sshpkt_put_cstring(ssh, service)) != 0 || 210 (r = sshpkt_send(ssh)) != 0 || 211 (r = ssh_packet_write_wait(ssh)) != 0) 212 goto out; 213 } else { 214 debug("bad service request %s", service); 215 ssh_packet_disconnect(ssh, "bad service request %s", service); 216 } 217 r = 0; 218 out: 219 free(service); 220 return r; 221 } 222 223 #define MIN_FAIL_DELAY_SECONDS 0.005 224 static double 225 user_specific_delay(const char *user) 226 { 227 char b[512]; 228 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 229 u_char *hash = xmalloc(len); 230 double delay; 231 232 (void)snprintf(b, sizeof b, "%llu%s", 233 (unsigned long long)options.timing_secret, user); 234 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 235 fatal("%s: ssh_digest_memory", __func__); 236 /* 0-4.2 ms of delay */ 237 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 238 freezero(hash, len); 239 debug3("%s: user specific delay %0.3lfms", __func__, delay/1000); 240 return MIN_FAIL_DELAY_SECONDS + delay; 241 } 242 243 static void 244 ensure_minimum_time_since(double start, double seconds) 245 { 246 struct timespec ts; 247 double elapsed = monotime_double() - start, req = seconds, remain; 248 249 /* if we've already passed the requested time, scale up */ 250 while ((remain = seconds - elapsed) < 0.0) 251 seconds *= 2; 252 253 ts.tv_sec = remain; 254 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; 255 debug3("%s: elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 256 __func__, elapsed*1000, remain*1000, req*1000); 257 nanosleep(&ts, NULL); 258 } 259 260 /*ARGSUSED*/ 261 static int 262 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 263 { 264 Authctxt *authctxt = ssh->authctxt; 265 Authmethod *m = NULL; 266 char *user = NULL, *service = NULL, *method = NULL, *style = NULL; 267 int r, authenticated = 0; 268 double tstart = monotime_double(); 269 270 if (authctxt == NULL) 271 fatal("input_userauth_request: no authctxt"); 272 273 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || 274 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 275 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) 276 goto out; 277 debug("userauth-request for user %s service %s method %s", user, service, method); 278 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 279 280 if ((style = strchr(user, ':')) != NULL) 281 *style++ = 0; 282 283 if (authctxt->attempt++ == 0) { 284 /* setup auth context */ 285 authctxt->pw = PRIVSEP(getpwnamallow(ssh, user)); 286 authctxt->user = xstrdup(user); 287 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 288 authctxt->valid = 1; 289 debug2("%s: setting up authctxt for %s", 290 __func__, user); 291 } else { 292 /* Invalid user, fake password information */ 293 authctxt->pw = fakepw(); 294 #ifdef SSH_AUDIT_EVENTS 295 PRIVSEP(audit_event(ssh, SSH_INVALID_USER)); 296 #endif 297 } 298 #ifdef USE_PAM 299 if (options.use_pam) 300 PRIVSEP(start_pam(ssh)); 301 #endif 302 ssh_packet_set_log_preamble(ssh, "%suser %s", 303 authctxt->valid ? "authenticating " : "invalid ", user); 304 setproctitle("%s%s", authctxt->valid ? user : "unknown", 305 use_privsep ? " [net]" : ""); 306 authctxt->service = xstrdup(service); 307 authctxt->style = style ? xstrdup(style) : NULL; 308 if (use_privsep) 309 mm_inform_authserv(service, style); 310 userauth_banner(ssh); 311 if (auth2_setup_methods_lists(authctxt) != 0) 312 ssh_packet_disconnect(ssh, 313 "no authentication methods enabled"); 314 } else if (strcmp(user, authctxt->user) != 0 || 315 strcmp(service, authctxt->service) != 0) { 316 ssh_packet_disconnect(ssh, "Change of username or service " 317 "not allowed: (%s,%s) -> (%s,%s)", 318 authctxt->user, authctxt->service, user, service); 319 } 320 /* reset state */ 321 auth2_challenge_stop(ssh); 322 323 #ifdef GSSAPI 324 /* XXX move to auth2_gssapi_stop() */ 325 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 326 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 327 #endif 328 329 auth2_authctxt_reset_info(authctxt); 330 authctxt->postponed = 0; 331 authctxt->server_caused_failure = 0; 332 333 /* try to authenticate user */ 334 m = authmethod_lookup(authctxt, method); 335 if (m != NULL && authctxt->failures < options.max_authtries) { 336 debug2("input_userauth_request: try method %s", method); 337 authenticated = m->userauth(ssh); 338 } 339 if (!authctxt->authenticated) 340 ensure_minimum_time_since(tstart, 341 user_specific_delay(authctxt->user)); 342 userauth_finish(ssh, authenticated, method, NULL); 343 r = 0; 344 out: 345 free(service); 346 free(user); 347 free(method); 348 return r; 349 } 350 351 void 352 userauth_finish(struct ssh *ssh, int authenticated, const char *method, 353 const char *submethod) 354 { 355 Authctxt *authctxt = ssh->authctxt; 356 char *methods; 357 int r, partial = 0; 358 359 if (!authctxt->valid && authenticated) 360 fatal("INTERNAL ERROR: authenticated invalid user %s", 361 authctxt->user); 362 if (authenticated && authctxt->postponed) 363 fatal("INTERNAL ERROR: authenticated and postponed"); 364 365 /* Special handling for root */ 366 if (authenticated && authctxt->pw->pw_uid == 0 && 367 !auth_root_allowed(ssh, method)) { 368 authenticated = 0; 369 #ifdef SSH_AUDIT_EVENTS 370 PRIVSEP(audit_event(ssh, SSH_LOGIN_ROOT_DENIED)); 371 #endif 372 } 373 374 if (authenticated && options.num_auth_methods != 0) { 375 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 376 authenticated = 0; 377 partial = 1; 378 } 379 } 380 381 /* Log before sending the reply */ 382 auth_log(ssh, authenticated, partial, method, submethod); 383 384 /* Update information exposed to session */ 385 if (authenticated || partial) 386 auth2_update_session_info(authctxt, method, submethod); 387 388 if (authctxt->postponed) 389 return; 390 391 #ifdef USE_PAM 392 if (options.use_pam && authenticated) { 393 int r; 394 395 if (!PRIVSEP(do_pam_account())) { 396 /* if PAM returned a message, send it to the user */ 397 if (sshbuf_len(loginmsg) > 0) { 398 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0) 399 fatal("%s: buffer error: %s", 400 __func__, ssh_err(r)); 401 userauth_send_banner(ssh, sshbuf_ptr(loginmsg)); 402 if ((r = ssh_packet_write_wait(ssh)) != 0) { 403 sshpkt_fatal(ssh, r, 404 "%s: send PAM banner", __func__); 405 } 406 } 407 fatal("Access denied for user %s by PAM account " 408 "configuration", authctxt->user); 409 } 410 } 411 #endif 412 413 if (authenticated == 1) { 414 /* turn off userauth */ 415 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 416 &dispatch_protocol_ignore); 417 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 418 (r = sshpkt_send(ssh)) != 0 || 419 (r = ssh_packet_write_wait(ssh)) != 0) 420 fatal("%s: %s", __func__, ssh_err(r)); 421 /* now we can break out */ 422 authctxt->success = 1; 423 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 424 } else { 425 /* Allow initial try of "none" auth without failure penalty */ 426 if (!partial && !authctxt->server_caused_failure && 427 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) 428 authctxt->failures++; 429 if (authctxt->failures >= options.max_authtries) { 430 #ifdef SSH_AUDIT_EVENTS 431 PRIVSEP(audit_event(ssh, SSH_LOGIN_EXCEED_MAXTRIES)); 432 #endif 433 auth_maxtries_exceeded(ssh); 434 } 435 methods = authmethods_get(authctxt); 436 debug3("%s: failure partial=%d next methods=\"%s\"", __func__, 437 partial, methods); 438 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 439 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 440 (r = sshpkt_put_u8(ssh, partial)) != 0 || 441 (r = sshpkt_send(ssh)) != 0 || 442 (r = ssh_packet_write_wait(ssh)) != 0) 443 fatal("%s: %s", __func__, ssh_err(r)); 444 free(methods); 445 } 446 } 447 448 /* 449 * Checks whether method is allowed by at least one AuthenticationMethods 450 * methods list. Returns 1 if allowed, or no methods lists configured. 451 * 0 otherwise. 452 */ 453 int 454 auth2_method_allowed(Authctxt *authctxt, const char *method, 455 const char *submethod) 456 { 457 u_int i; 458 459 /* 460 * NB. authctxt->num_auth_methods might be zero as a result of 461 * auth2_setup_methods_lists(), so check the configuration. 462 */ 463 if (options.num_auth_methods == 0) 464 return 1; 465 for (i = 0; i < authctxt->num_auth_methods; i++) { 466 if (list_starts_with(authctxt->auth_methods[i], method, 467 submethod) != MATCH_NONE) 468 return 1; 469 } 470 return 0; 471 } 472 473 static char * 474 authmethods_get(Authctxt *authctxt) 475 { 476 struct sshbuf *b; 477 char *list; 478 int i, r; 479 480 if ((b = sshbuf_new()) == NULL) 481 fatal("%s: sshbuf_new failed", __func__); 482 for (i = 0; authmethods[i] != NULL; i++) { 483 if (strcmp(authmethods[i]->name, "none") == 0) 484 continue; 485 if (authmethods[i]->enabled == NULL || 486 *(authmethods[i]->enabled) == 0) 487 continue; 488 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 489 NULL)) 490 continue; 491 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 492 authmethods[i]->name)) != 0) 493 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 494 } 495 if ((list = sshbuf_dup_string(b)) == NULL) 496 fatal("%s: sshbuf_dup_string failed", __func__); 497 sshbuf_free(b); 498 return list; 499 } 500 501 static Authmethod * 502 authmethod_lookup(Authctxt *authctxt, const char *name) 503 { 504 int i; 505 506 if (name != NULL) 507 for (i = 0; authmethods[i] != NULL; i++) 508 if (authmethods[i]->enabled != NULL && 509 *(authmethods[i]->enabled) != 0 && 510 strcmp(name, authmethods[i]->name) == 0 && 511 auth2_method_allowed(authctxt, 512 authmethods[i]->name, NULL)) 513 return authmethods[i]; 514 debug2("Unrecognized authentication method name: %s", 515 name ? name : "NULL"); 516 return NULL; 517 } 518 519 /* 520 * Check a comma-separated list of methods for validity. Is need_enable is 521 * non-zero, then also require that the methods are enabled. 522 * Returns 0 on success or -1 if the methods list is invalid. 523 */ 524 int 525 auth2_methods_valid(const char *_methods, int need_enable) 526 { 527 char *methods, *omethods, *method, *p; 528 u_int i, found; 529 int ret = -1; 530 531 if (*_methods == '\0') { 532 error("empty authentication method list"); 533 return -1; 534 } 535 omethods = methods = xstrdup(_methods); 536 while ((method = strsep(&methods, ",")) != NULL) { 537 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 538 if ((p = strchr(method, ':')) != NULL) 539 *p = '\0'; 540 if (strcmp(method, authmethods[i]->name) != 0) 541 continue; 542 if (need_enable) { 543 if (authmethods[i]->enabled == NULL || 544 *(authmethods[i]->enabled) == 0) { 545 error("Disabled method \"%s\" in " 546 "AuthenticationMethods list \"%s\"", 547 method, _methods); 548 goto out; 549 } 550 } 551 found = 1; 552 break; 553 } 554 if (!found) { 555 error("Unknown authentication method \"%s\" in list", 556 method); 557 goto out; 558 } 559 } 560 ret = 0; 561 out: 562 free(omethods); 563 return ret; 564 } 565 566 /* 567 * Prune the AuthenticationMethods supplied in the configuration, removing 568 * any methods lists that include disabled methods. Note that this might 569 * leave authctxt->num_auth_methods == 0, even when multiple required auth 570 * has been requested. For this reason, all tests for whether multiple is 571 * enabled should consult options.num_auth_methods directly. 572 */ 573 int 574 auth2_setup_methods_lists(Authctxt *authctxt) 575 { 576 u_int i; 577 578 /* First, normalise away the "any" pseudo-method */ 579 if (options.num_auth_methods == 1 && 580 strcmp(options.auth_methods[0], "any") == 0) { 581 free(options.auth_methods[0]); 582 options.auth_methods[0] = NULL; 583 options.num_auth_methods = 0; 584 } 585 586 if (options.num_auth_methods == 0) 587 return 0; 588 debug3("%s: checking methods", __func__); 589 authctxt->auth_methods = xcalloc(options.num_auth_methods, 590 sizeof(*authctxt->auth_methods)); 591 authctxt->num_auth_methods = 0; 592 for (i = 0; i < options.num_auth_methods; i++) { 593 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 594 logit("Authentication methods list \"%s\" contains " 595 "disabled method, skipping", 596 options.auth_methods[i]); 597 continue; 598 } 599 debug("authentication methods list %d: %s", 600 authctxt->num_auth_methods, options.auth_methods[i]); 601 authctxt->auth_methods[authctxt->num_auth_methods++] = 602 xstrdup(options.auth_methods[i]); 603 } 604 if (authctxt->num_auth_methods == 0) { 605 error("No AuthenticationMethods left after eliminating " 606 "disabled methods"); 607 return -1; 608 } 609 return 0; 610 } 611 612 static int 613 list_starts_with(const char *methods, const char *method, 614 const char *submethod) 615 { 616 size_t l = strlen(method); 617 int match; 618 const char *p; 619 620 if (strncmp(methods, method, l) != 0) 621 return MATCH_NONE; 622 p = methods + l; 623 match = MATCH_METHOD; 624 if (*p == ':') { 625 if (!submethod) 626 return MATCH_PARTIAL; 627 l = strlen(submethod); 628 p += 1; 629 if (strncmp(submethod, p, l)) 630 return MATCH_NONE; 631 p += l; 632 match = MATCH_BOTH; 633 } 634 if (*p != ',' && *p != '\0') 635 return MATCH_NONE; 636 return match; 637 } 638 639 /* 640 * Remove method from the start of a comma-separated list of methods. 641 * Returns 0 if the list of methods did not start with that method or 1 642 * if it did. 643 */ 644 static int 645 remove_method(char **methods, const char *method, const char *submethod) 646 { 647 char *omethods = *methods, *p; 648 size_t l = strlen(method); 649 int match; 650 651 match = list_starts_with(omethods, method, submethod); 652 if (match != MATCH_METHOD && match != MATCH_BOTH) 653 return 0; 654 p = omethods + l; 655 if (submethod && match == MATCH_BOTH) 656 p += 1 + strlen(submethod); /* include colon */ 657 if (*p == ',') 658 p++; 659 *methods = xstrdup(p); 660 free(omethods); 661 return 1; 662 } 663 664 /* 665 * Called after successful authentication. Will remove the successful method 666 * from the start of each list in which it occurs. If it was the last method 667 * in any list, then authentication is deemed successful. 668 * Returns 1 if the method completed any authentication list or 0 otherwise. 669 */ 670 int 671 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 672 const char *submethod) 673 { 674 u_int i, found = 0; 675 676 debug3("%s: updating methods list after \"%s\"", __func__, method); 677 for (i = 0; i < authctxt->num_auth_methods; i++) { 678 if (!remove_method(&(authctxt->auth_methods[i]), method, 679 submethod)) 680 continue; 681 found = 1; 682 if (*authctxt->auth_methods[i] == '\0') { 683 debug2("authentication methods list %d complete", i); 684 return 1; 685 } 686 debug3("authentication methods list %d remaining: \"%s\"", 687 i, authctxt->auth_methods[i]); 688 } 689 /* This should not happen, but would be bad if it did */ 690 if (!found) 691 fatal("%s: method not in AuthenticationMethods", __func__); 692 return 0; 693 } 694 695 /* Reset method-specific information */ 696 void auth2_authctxt_reset_info(Authctxt *authctxt) 697 { 698 sshkey_free(authctxt->auth_method_key); 699 free(authctxt->auth_method_info); 700 authctxt->auth_method_key = NULL; 701 authctxt->auth_method_info = NULL; 702 } 703 704 /* Record auth method-specific information for logs */ 705 void 706 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 707 { 708 va_list ap; 709 int i; 710 711 free(authctxt->auth_method_info); 712 authctxt->auth_method_info = NULL; 713 714 va_start(ap, fmt); 715 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 716 va_end(ap); 717 718 if (i == -1) 719 fatal("%s: vasprintf failed", __func__); 720 } 721 722 /* 723 * Records a public key used in authentication. This is used for logging 724 * and to ensure that the same key is not subsequently accepted again for 725 * multiple authentication. 726 */ 727 void 728 auth2_record_key(Authctxt *authctxt, int authenticated, 729 const struct sshkey *key) 730 { 731 struct sshkey **tmp, *dup; 732 int r; 733 734 if ((r = sshkey_from_private(key, &dup)) != 0) 735 fatal("%s: copy key: %s", __func__, ssh_err(r)); 736 sshkey_free(authctxt->auth_method_key); 737 authctxt->auth_method_key = dup; 738 739 if (!authenticated) 740 return; 741 742 /* If authenticated, make sure we don't accept this key again */ 743 if ((r = sshkey_from_private(key, &dup)) != 0) 744 fatal("%s: copy key: %s", __func__, ssh_err(r)); 745 if (authctxt->nprev_keys >= INT_MAX || 746 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 747 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 748 fatal("%s: reallocarray failed", __func__); 749 authctxt->prev_keys = tmp; 750 authctxt->prev_keys[authctxt->nprev_keys] = dup; 751 authctxt->nprev_keys++; 752 753 } 754 755 /* Checks whether a key has already been previously used for authentication */ 756 int 757 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 758 { 759 u_int i; 760 char *fp; 761 762 for (i = 0; i < authctxt->nprev_keys; i++) { 763 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 764 fp = sshkey_fingerprint(authctxt->prev_keys[i], 765 options.fingerprint_hash, SSH_FP_DEFAULT); 766 debug3("%s: key already used: %s %s", __func__, 767 sshkey_type(authctxt->prev_keys[i]), 768 fp == NULL ? "UNKNOWN" : fp); 769 free(fp); 770 return 1; 771 } 772 } 773 return 0; 774 } 775 776 /* 777 * Updates authctxt->session_info with details of authentication. Should be 778 * whenever an authentication method succeeds. 779 */ 780 void 781 auth2_update_session_info(Authctxt *authctxt, const char *method, 782 const char *submethod) 783 { 784 int r; 785 786 if (authctxt->session_info == NULL) { 787 if ((authctxt->session_info = sshbuf_new()) == NULL) 788 fatal("%s: sshbuf_new", __func__); 789 } 790 791 /* Append method[/submethod] */ 792 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 793 method, submethod == NULL ? "" : "/", 794 submethod == NULL ? "" : submethod)) != 0) 795 fatal("%s: append method: %s", __func__, ssh_err(r)); 796 797 /* Append key if present */ 798 if (authctxt->auth_method_key != NULL) { 799 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 800 (r = sshkey_format_text(authctxt->auth_method_key, 801 authctxt->session_info)) != 0) 802 fatal("%s: append key: %s", __func__, ssh_err(r)); 803 } 804 805 if (authctxt->auth_method_info != NULL) { 806 /* Ensure no ambiguity here */ 807 if (strchr(authctxt->auth_method_info, '\n') != NULL) 808 fatal("%s: auth_method_info contains \\n", __func__); 809 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 810 (r = sshbuf_putf(authctxt->session_info, "%s", 811 authctxt->auth_method_info)) != 0) { 812 fatal("%s: append method info: %s", 813 __func__, ssh_err(r)); 814 } 815 } 816 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 817 fatal("%s: append: %s", __func__, ssh_err(r)); 818 } 819 820