1 /* $OpenBSD: auth2.c,v 1.155 2019/03/25 22:34:52 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 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 "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 57 #ifdef GSSAPI 58 #include "ssh-gss.h" 59 #endif 60 #include "monitor_wrap.h" 61 #include "ssherr.h" 62 #include "digest.h" 63 64 /* import */ 65 extern ServerOptions options; 66 extern u_char *session_id2; 67 extern u_int session_id2_len; 68 extern struct sshbuf *loginmsg; 69 70 /* methods */ 71 72 extern Authmethod method_none; 73 extern Authmethod method_pubkey; 74 extern Authmethod method_passwd; 75 extern Authmethod method_kbdint; 76 extern Authmethod method_hostbased; 77 #ifdef GSSAPI 78 extern Authmethod method_gssapi; 79 #endif 80 81 Authmethod *authmethods[] = { 82 &method_none, 83 &method_pubkey, 84 #ifdef GSSAPI 85 &method_gssapi, 86 #endif 87 &method_passwd, 88 &method_kbdint, 89 &method_hostbased, 90 NULL 91 }; 92 93 /* protocol */ 94 95 static int input_service_request(int, u_int32_t, struct ssh *); 96 static int input_userauth_request(int, u_int32_t, struct ssh *); 97 98 /* helper */ 99 static Authmethod *authmethod_lookup(Authctxt *, const char *); 100 static char *authmethods_get(Authctxt *authctxt); 101 102 #define MATCH_NONE 0 /* method or submethod mismatch */ 103 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 104 #define MATCH_BOTH 2 /* method and submethod match */ 105 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 106 static int list_starts_with(const char *, const char *, const char *); 107 108 char * 109 auth2_read_banner(void) 110 { 111 struct stat st; 112 char *banner = NULL; 113 size_t len, n; 114 int fd; 115 116 if ((fd = open(options.banner, O_RDONLY)) == -1) 117 return (NULL); 118 if (fstat(fd, &st) == -1) { 119 close(fd); 120 return (NULL); 121 } 122 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 123 close(fd); 124 return (NULL); 125 } 126 127 len = (size_t)st.st_size; /* truncate */ 128 banner = xmalloc(len + 1); 129 n = atomicio(read, fd, banner, len); 130 close(fd); 131 132 if (n != len) { 133 free(banner); 134 return (NULL); 135 } 136 banner[n] = '\0'; 137 138 return (banner); 139 } 140 141 static void 142 userauth_send_banner(struct ssh *ssh, const char *msg) 143 { 144 int r; 145 146 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 || 147 (r = sshpkt_put_cstring(ssh, msg)) != 0 || 148 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */ 149 (r = sshpkt_send(ssh)) != 0) 150 fatal("%s: %s", __func__, ssh_err(r)); 151 debug("%s: sent", __func__); 152 } 153 154 static void 155 userauth_banner(struct ssh *ssh) 156 { 157 char *banner = NULL; 158 159 if (options.banner == NULL) 160 return; 161 162 if ((banner = PRIVSEP(auth2_read_banner())) == NULL) 163 goto done; 164 userauth_send_banner(ssh, banner); 165 166 done: 167 free(banner); 168 } 169 170 /* 171 * loop until authctxt->success == TRUE 172 */ 173 void 174 do_authentication2(struct ssh *ssh) 175 { 176 Authctxt *authctxt = ssh->authctxt; 177 178 ssh_dispatch_init(ssh, &dispatch_protocol_error); 179 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); 180 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); 181 ssh->authctxt = NULL; 182 } 183 184 /*ARGSUSED*/ 185 static int 186 input_service_request(int type, u_int32_t seq, struct ssh *ssh) 187 { 188 Authctxt *authctxt = ssh->authctxt; 189 char *service = NULL; 190 int r, acceptit = 0; 191 192 if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 193 (r = sshpkt_get_end(ssh)) != 0) 194 goto out; 195 196 if (authctxt == NULL) 197 fatal("input_service_request: no authctxt"); 198 199 if (strcmp(service, "ssh-userauth") == 0) { 200 if (!authctxt->success) { 201 acceptit = 1; 202 /* now we can handle user-auth requests */ 203 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 204 &input_userauth_request); 205 } 206 } 207 /* XXX all other service requests are denied */ 208 209 if (acceptit) { 210 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 || 211 (r = sshpkt_put_cstring(ssh, service)) != 0 || 212 (r = sshpkt_send(ssh)) != 0 || 213 (r = ssh_packet_write_wait(ssh)) != 0) 214 goto out; 215 } else { 216 debug("bad service request %s", service); 217 ssh_packet_disconnect(ssh, "bad service request %s", service); 218 } 219 r = 0; 220 out: 221 free(service); 222 return 0; 223 } 224 225 #define MIN_FAIL_DELAY_SECONDS 0.005 226 static double 227 user_specific_delay(const char *user) 228 { 229 char b[512]; 230 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 231 u_char *hash = xmalloc(len); 232 double delay; 233 234 (void)snprintf(b, sizeof b, "%llu%s", 235 (unsigned long long)options.timing_secret, user); 236 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 237 fatal("%s: ssh_digest_memory", __func__); 238 /* 0-4.2 ms of delay */ 239 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 240 freezero(hash, len); 241 debug3("%s: user specific delay %0.3lfms", __func__, delay/1000); 242 return MIN_FAIL_DELAY_SECONDS + delay; 243 } 244 245 static void 246 ensure_minimum_time_since(double start, double seconds) 247 { 248 struct timespec ts; 249 double elapsed = monotime_double() - start, req = seconds, remain; 250 251 /* if we've already passed the requested time, scale up */ 252 while ((remain = seconds - elapsed) < 0.0) 253 seconds *= 2; 254 255 ts.tv_sec = remain; 256 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; 257 debug3("%s: elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 258 __func__, elapsed*1000, remain*1000, req*1000); 259 nanosleep(&ts, NULL); 260 } 261 262 /*ARGSUSED*/ 263 static int 264 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 265 { 266 Authctxt *authctxt = ssh->authctxt; 267 Authmethod *m = NULL; 268 char *user = NULL, *service = NULL, *method = NULL, *style = NULL; 269 int r, authenticated = 0; 270 double tstart = monotime_double(); 271 272 if (authctxt == NULL) 273 fatal("input_userauth_request: no authctxt"); 274 275 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || 276 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 277 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) 278 goto out; 279 debug("userauth-request for user %s service %s method %s", user, service, method); 280 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 281 282 if ((style = strchr(user, ':')) != NULL) 283 *style++ = 0; 284 285 if (authctxt->attempt++ == 0) { 286 /* setup auth context */ 287 authctxt->pw = PRIVSEP(getpwnamallow(ssh, user)); 288 authctxt->user = xstrdup(user); 289 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 290 authctxt->valid = 1; 291 debug2("%s: setting up authctxt for %s", 292 __func__, user); 293 } else { 294 /* Invalid user, fake password information */ 295 authctxt->pw = fakepw(); 296 #ifdef SSH_AUDIT_EVENTS 297 PRIVSEP(audit_event(ssh, SSH_INVALID_USER)); 298 #endif 299 } 300 #ifdef USE_PAM 301 if (options.use_pam) 302 PRIVSEP(start_pam(ssh)); 303 #endif 304 ssh_packet_set_log_preamble(ssh, "%suser %s", 305 authctxt->valid ? "authenticating " : "invalid ", user); 306 setproctitle("%s%s", authctxt->valid ? user : "unknown", 307 use_privsep ? " [net]" : ""); 308 authctxt->service = xstrdup(service); 309 authctxt->style = style ? xstrdup(style) : NULL; 310 if (use_privsep) 311 mm_inform_authserv(service, style); 312 userauth_banner(ssh); 313 if (auth2_setup_methods_lists(authctxt) != 0) 314 ssh_packet_disconnect(ssh, 315 "no authentication methods enabled"); 316 } else if (strcmp(user, authctxt->user) != 0 || 317 strcmp(service, authctxt->service) != 0) { 318 ssh_packet_disconnect(ssh, "Change of username or service " 319 "not allowed: (%s,%s) -> (%s,%s)", 320 authctxt->user, authctxt->service, user, service); 321 } 322 /* reset state */ 323 auth2_challenge_stop(ssh); 324 325 #ifdef GSSAPI 326 /* XXX move to auth2_gssapi_stop() */ 327 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 328 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 329 #endif 330 331 auth2_authctxt_reset_info(authctxt); 332 authctxt->postponed = 0; 333 authctxt->server_caused_failure = 0; 334 335 /* try to authenticate user */ 336 m = authmethod_lookup(authctxt, method); 337 if (m != NULL && authctxt->failures < options.max_authtries) { 338 debug2("input_userauth_request: try method %s", method); 339 authenticated = m->userauth(ssh); 340 } 341 if (!authctxt->authenticated) 342 ensure_minimum_time_since(tstart, 343 user_specific_delay(authctxt->user)); 344 userauth_finish(ssh, authenticated, method, NULL); 345 r = 0; 346 out: 347 free(service); 348 free(user); 349 free(method); 350 return r; 351 } 352 353 void 354 userauth_finish(struct ssh *ssh, int authenticated, const char *method, 355 const char *submethod) 356 { 357 Authctxt *authctxt = ssh->authctxt; 358 char *methods; 359 int r, partial = 0; 360 361 if (!authctxt->valid && authenticated) 362 fatal("INTERNAL ERROR: authenticated invalid user %s", 363 authctxt->user); 364 if (authenticated && authctxt->postponed) 365 fatal("INTERNAL ERROR: authenticated and postponed"); 366 367 /* Special handling for root */ 368 if (authenticated && authctxt->pw->pw_uid == 0 && 369 !auth_root_allowed(ssh, method)) { 370 authenticated = 0; 371 #ifdef SSH_AUDIT_EVENTS 372 PRIVSEP(audit_event(ssh, SSH_LOGIN_ROOT_DENIED)); 373 #endif 374 } 375 376 if (authenticated && options.num_auth_methods != 0) { 377 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 378 authenticated = 0; 379 partial = 1; 380 } 381 } 382 383 /* Log before sending the reply */ 384 auth_log(ssh, authenticated, partial, method, submethod); 385 386 /* Update information exposed to session */ 387 if (authenticated || partial) 388 auth2_update_session_info(authctxt, method, submethod); 389 390 if (authctxt->postponed) 391 return; 392 393 #ifdef USE_PAM 394 if (options.use_pam && authenticated) { 395 int r; 396 397 if (!PRIVSEP(do_pam_account())) { 398 /* if PAM returned a message, send it to the user */ 399 if (sshbuf_len(loginmsg) > 0) { 400 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0) 401 fatal("%s: buffer error: %s", 402 __func__, ssh_err(r)); 403 userauth_send_banner(ssh, sshbuf_ptr(loginmsg)); 404 if ((r = ssh_packet_write_wait(ssh)) != 0) { 405 sshpkt_fatal(ssh, r, 406 "%s: send PAM banner", __func__); 407 } 408 } 409 fatal("Access denied for user %s by PAM account " 410 "configuration", authctxt->user); 411 } 412 } 413 #endif 414 415 if (authenticated == 1) { 416 /* turn off userauth */ 417 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 418 &dispatch_protocol_ignore); 419 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 420 (r = sshpkt_send(ssh)) != 0 || 421 (r = ssh_packet_write_wait(ssh)) != 0) 422 fatal("%s: %s", __func__, ssh_err(r)); 423 /* now we can break out */ 424 authctxt->success = 1; 425 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 426 } else { 427 /* Allow initial try of "none" auth without failure penalty */ 428 if (!partial && !authctxt->server_caused_failure && 429 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) 430 authctxt->failures++; 431 if (authctxt->failures >= options.max_authtries) { 432 #ifdef SSH_AUDIT_EVENTS 433 PRIVSEP(audit_event(ssh, SSH_LOGIN_EXCEED_MAXTRIES)); 434 #endif 435 auth_maxtries_exceeded(ssh); 436 } 437 methods = authmethods_get(authctxt); 438 debug3("%s: failure partial=%d next methods=\"%s\"", __func__, 439 partial, methods); 440 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 441 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 442 (r = sshpkt_put_u8(ssh, partial)) != 0 || 443 (r = sshpkt_send(ssh)) != 0 || 444 (r = ssh_packet_write_wait(ssh)) != 0) 445 fatal("%s: %s", __func__, ssh_err(r)); 446 free(methods); 447 } 448 } 449 450 /* 451 * Checks whether method is allowed by at least one AuthenticationMethods 452 * methods list. Returns 1 if allowed, or no methods lists configured. 453 * 0 otherwise. 454 */ 455 int 456 auth2_method_allowed(Authctxt *authctxt, const char *method, 457 const char *submethod) 458 { 459 u_int i; 460 461 /* 462 * NB. authctxt->num_auth_methods might be zero as a result of 463 * auth2_setup_methods_lists(), so check the configuration. 464 */ 465 if (options.num_auth_methods == 0) 466 return 1; 467 for (i = 0; i < authctxt->num_auth_methods; i++) { 468 if (list_starts_with(authctxt->auth_methods[i], method, 469 submethod) != MATCH_NONE) 470 return 1; 471 } 472 return 0; 473 } 474 475 static char * 476 authmethods_get(Authctxt *authctxt) 477 { 478 struct sshbuf *b; 479 char *list; 480 int i, r; 481 482 if ((b = sshbuf_new()) == NULL) 483 fatal("%s: sshbuf_new failed", __func__); 484 for (i = 0; authmethods[i] != NULL; i++) { 485 if (strcmp(authmethods[i]->name, "none") == 0) 486 continue; 487 if (authmethods[i]->enabled == NULL || 488 *(authmethods[i]->enabled) == 0) 489 continue; 490 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 491 NULL)) 492 continue; 493 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 494 authmethods[i]->name)) != 0) 495 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 496 } 497 if ((list = sshbuf_dup_string(b)) == NULL) 498 fatal("%s: sshbuf_dup_string failed", __func__); 499 sshbuf_free(b); 500 return list; 501 } 502 503 static Authmethod * 504 authmethod_lookup(Authctxt *authctxt, const char *name) 505 { 506 int i; 507 508 if (name != NULL) 509 for (i = 0; authmethods[i] != NULL; i++) 510 if (authmethods[i]->enabled != NULL && 511 *(authmethods[i]->enabled) != 0 && 512 strcmp(name, authmethods[i]->name) == 0 && 513 auth2_method_allowed(authctxt, 514 authmethods[i]->name, NULL)) 515 return authmethods[i]; 516 debug2("Unrecognized authentication method name: %s", 517 name ? name : "NULL"); 518 return NULL; 519 } 520 521 /* 522 * Check a comma-separated list of methods for validity. Is need_enable is 523 * non-zero, then also require that the methods are enabled. 524 * Returns 0 on success or -1 if the methods list is invalid. 525 */ 526 int 527 auth2_methods_valid(const char *_methods, int need_enable) 528 { 529 char *methods, *omethods, *method, *p; 530 u_int i, found; 531 int ret = -1; 532 533 if (*_methods == '\0') { 534 error("empty authentication method list"); 535 return -1; 536 } 537 omethods = methods = xstrdup(_methods); 538 while ((method = strsep(&methods, ",")) != NULL) { 539 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 540 if ((p = strchr(method, ':')) != NULL) 541 *p = '\0'; 542 if (strcmp(method, authmethods[i]->name) != 0) 543 continue; 544 if (need_enable) { 545 if (authmethods[i]->enabled == NULL || 546 *(authmethods[i]->enabled) == 0) { 547 error("Disabled method \"%s\" in " 548 "AuthenticationMethods list \"%s\"", 549 method, _methods); 550 goto out; 551 } 552 } 553 found = 1; 554 break; 555 } 556 if (!found) { 557 error("Unknown authentication method \"%s\" in list", 558 method); 559 goto out; 560 } 561 } 562 ret = 0; 563 out: 564 free(omethods); 565 return ret; 566 } 567 568 /* 569 * Prune the AuthenticationMethods supplied in the configuration, removing 570 * any methods lists that include disabled methods. Note that this might 571 * leave authctxt->num_auth_methods == 0, even when multiple required auth 572 * has been requested. For this reason, all tests for whether multiple is 573 * enabled should consult options.num_auth_methods directly. 574 */ 575 int 576 auth2_setup_methods_lists(Authctxt *authctxt) 577 { 578 u_int i; 579 580 /* First, normalise away the "any" pseudo-method */ 581 if (options.num_auth_methods == 1 && 582 strcmp(options.auth_methods[0], "any") == 0) { 583 free(options.auth_methods[0]); 584 options.auth_methods[0] = NULL; 585 options.num_auth_methods = 0; 586 } 587 588 if (options.num_auth_methods == 0) 589 return 0; 590 debug3("%s: checking methods", __func__); 591 authctxt->auth_methods = xcalloc(options.num_auth_methods, 592 sizeof(*authctxt->auth_methods)); 593 authctxt->num_auth_methods = 0; 594 for (i = 0; i < options.num_auth_methods; i++) { 595 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 596 logit("Authentication methods list \"%s\" contains " 597 "disabled method, skipping", 598 options.auth_methods[i]); 599 continue; 600 } 601 debug("authentication methods list %d: %s", 602 authctxt->num_auth_methods, options.auth_methods[i]); 603 authctxt->auth_methods[authctxt->num_auth_methods++] = 604 xstrdup(options.auth_methods[i]); 605 } 606 if (authctxt->num_auth_methods == 0) { 607 error("No AuthenticationMethods left after eliminating " 608 "disabled methods"); 609 return -1; 610 } 611 return 0; 612 } 613 614 static int 615 list_starts_with(const char *methods, const char *method, 616 const char *submethod) 617 { 618 size_t l = strlen(method); 619 int match; 620 const char *p; 621 622 if (strncmp(methods, method, l) != 0) 623 return MATCH_NONE; 624 p = methods + l; 625 match = MATCH_METHOD; 626 if (*p == ':') { 627 if (!submethod) 628 return MATCH_PARTIAL; 629 l = strlen(submethod); 630 p += 1; 631 if (strncmp(submethod, p, l)) 632 return MATCH_NONE; 633 p += l; 634 match = MATCH_BOTH; 635 } 636 if (*p != ',' && *p != '\0') 637 return MATCH_NONE; 638 return match; 639 } 640 641 /* 642 * Remove method from the start of a comma-separated list of methods. 643 * Returns 0 if the list of methods did not start with that method or 1 644 * if it did. 645 */ 646 static int 647 remove_method(char **methods, const char *method, const char *submethod) 648 { 649 char *omethods = *methods, *p; 650 size_t l = strlen(method); 651 int match; 652 653 match = list_starts_with(omethods, method, submethod); 654 if (match != MATCH_METHOD && match != MATCH_BOTH) 655 return 0; 656 p = omethods + l; 657 if (submethod && match == MATCH_BOTH) 658 p += 1 + strlen(submethod); /* include colon */ 659 if (*p == ',') 660 p++; 661 *methods = xstrdup(p); 662 free(omethods); 663 return 1; 664 } 665 666 /* 667 * Called after successful authentication. Will remove the successful method 668 * from the start of each list in which it occurs. If it was the last method 669 * in any list, then authentication is deemed successful. 670 * Returns 1 if the method completed any authentication list or 0 otherwise. 671 */ 672 int 673 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 674 const char *submethod) 675 { 676 u_int i, found = 0; 677 678 debug3("%s: updating methods list after \"%s\"", __func__, method); 679 for (i = 0; i < authctxt->num_auth_methods; i++) { 680 if (!remove_method(&(authctxt->auth_methods[i]), method, 681 submethod)) 682 continue; 683 found = 1; 684 if (*authctxt->auth_methods[i] == '\0') { 685 debug2("authentication methods list %d complete", i); 686 return 1; 687 } 688 debug3("authentication methods list %d remaining: \"%s\"", 689 i, authctxt->auth_methods[i]); 690 } 691 /* This should not happen, but would be bad if it did */ 692 if (!found) 693 fatal("%s: method not in AuthenticationMethods", __func__); 694 return 0; 695 } 696 697 /* Reset method-specific information */ 698 void auth2_authctxt_reset_info(Authctxt *authctxt) 699 { 700 sshkey_free(authctxt->auth_method_key); 701 free(authctxt->auth_method_info); 702 authctxt->auth_method_key = NULL; 703 authctxt->auth_method_info = NULL; 704 } 705 706 /* Record auth method-specific information for logs */ 707 void 708 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 709 { 710 va_list ap; 711 int i; 712 713 free(authctxt->auth_method_info); 714 authctxt->auth_method_info = NULL; 715 716 va_start(ap, fmt); 717 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 718 va_end(ap); 719 720 if (i < 0 || authctxt->auth_method_info == NULL) 721 fatal("%s: vasprintf failed", __func__); 722 } 723 724 /* 725 * Records a public key used in authentication. This is used for logging 726 * and to ensure that the same key is not subsequently accepted again for 727 * multiple authentication. 728 */ 729 void 730 auth2_record_key(Authctxt *authctxt, int authenticated, 731 const struct sshkey *key) 732 { 733 struct sshkey **tmp, *dup; 734 int r; 735 736 if ((r = sshkey_from_private(key, &dup)) != 0) 737 fatal("%s: copy key: %s", __func__, ssh_err(r)); 738 sshkey_free(authctxt->auth_method_key); 739 authctxt->auth_method_key = dup; 740 741 if (!authenticated) 742 return; 743 744 /* If authenticated, make sure we don't accept this key again */ 745 if ((r = sshkey_from_private(key, &dup)) != 0) 746 fatal("%s: copy key: %s", __func__, ssh_err(r)); 747 if (authctxt->nprev_keys >= INT_MAX || 748 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 749 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 750 fatal("%s: reallocarray failed", __func__); 751 authctxt->prev_keys = tmp; 752 authctxt->prev_keys[authctxt->nprev_keys] = dup; 753 authctxt->nprev_keys++; 754 755 } 756 757 /* Checks whether a key has already been previously used for authentication */ 758 int 759 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 760 { 761 u_int i; 762 char *fp; 763 764 for (i = 0; i < authctxt->nprev_keys; i++) { 765 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 766 fp = sshkey_fingerprint(authctxt->prev_keys[i], 767 options.fingerprint_hash, SSH_FP_DEFAULT); 768 debug3("%s: key already used: %s %s", __func__, 769 sshkey_type(authctxt->prev_keys[i]), 770 fp == NULL ? "UNKNOWN" : fp); 771 free(fp); 772 return 1; 773 } 774 } 775 return 0; 776 } 777 778 /* 779 * Updates authctxt->session_info with details of authentication. Should be 780 * whenever an authentication method succeeds. 781 */ 782 void 783 auth2_update_session_info(Authctxt *authctxt, const char *method, 784 const char *submethod) 785 { 786 int r; 787 788 if (authctxt->session_info == NULL) { 789 if ((authctxt->session_info = sshbuf_new()) == NULL) 790 fatal("%s: sshbuf_new", __func__); 791 } 792 793 /* Append method[/submethod] */ 794 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 795 method, submethod == NULL ? "" : "/", 796 submethod == NULL ? "" : submethod)) != 0) 797 fatal("%s: append method: %s", __func__, ssh_err(r)); 798 799 /* Append key if present */ 800 if (authctxt->auth_method_key != NULL) { 801 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 802 (r = sshkey_format_text(authctxt->auth_method_key, 803 authctxt->session_info)) != 0) 804 fatal("%s: append key: %s", __func__, ssh_err(r)); 805 } 806 807 if (authctxt->auth_method_info != NULL) { 808 /* Ensure no ambiguity here */ 809 if (strchr(authctxt->auth_method_info, '\n') != NULL) 810 fatal("%s: auth_method_info contains \\n", __func__); 811 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 812 (r = sshbuf_putf(authctxt->session_info, "%s", 813 authctxt->auth_method_info)) != 0) { 814 fatal("%s: append method info: %s", 815 __func__, ssh_err(r)); 816 } 817 } 818 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 819 fatal("%s: append: %s", __func__, ssh_err(r)); 820 } 821 822