1 /* $NetBSD: auth2.c,v 1.22 2020/05/28 17:05:49 christos Exp $ */ 2 /* $OpenBSD: auth2.c,v 1.158 2020/03/06 18:16:21 markus Exp $ */ 3 /* 4 * Copyright (c) 2000 Markus Friedl. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 __RCSID("$NetBSD: auth2.c,v 1.22 2020/05/28 17:05:49 christos Exp $"); 29 30 #include <sys/types.h> 31 #include <sys/stat.h> 32 #include <sys/uio.h> 33 34 #include <fcntl.h> 35 #include <limits.h> 36 #include <pwd.h> 37 #include <stdarg.h> 38 #include <string.h> 39 #include <unistd.h> 40 #include <time.h> 41 42 #include "stdlib.h" 43 #include "atomicio.h" 44 #include "xmalloc.h" 45 #include "ssh2.h" 46 #include "packet.h" 47 #include "log.h" 48 #include "sshbuf.h" 49 #include "misc.h" 50 #include "servconf.h" 51 #include "compat.h" 52 #include "sshkey.h" 53 #include "hostfile.h" 54 #include "auth.h" 55 #include "dispatch.h" 56 #include "pathnames.h" 57 #include "canohost.h" 58 #include "pfilter.h" 59 60 #ifdef GSSAPI 61 #include "ssh-gss.h" 62 #endif 63 64 #include "monitor_wrap.h" 65 #include "ssherr.h" 66 #include "digest.h" 67 68 /* import */ 69 extern ServerOptions options; 70 extern u_char *session_id2; 71 extern u_int session_id2_len; 72 extern struct sshbuf *loginmsg; 73 74 /* methods */ 75 76 extern Authmethod method_none; 77 extern Authmethod method_pubkey; 78 extern Authmethod method_passwd; 79 extern Authmethod method_kbdint; 80 extern Authmethod method_hostbased; 81 #ifdef KRB5 82 extern Authmethod method_kerberos; 83 #endif 84 #ifdef GSSAPI 85 extern Authmethod method_gssapi; 86 #endif 87 88 static int log_flag = 0; 89 90 Authmethod *authmethods[] = { 91 &method_none, 92 &method_pubkey, 93 #ifdef GSSAPI 94 &method_gssapi, 95 #endif 96 &method_passwd, 97 &method_kbdint, 98 &method_hostbased, 99 #ifdef KRB5 100 &method_kerberos, 101 #endif 102 NULL 103 }; 104 105 /* protocol */ 106 107 static int input_service_request(int, u_int32_t, struct ssh *); 108 static int input_userauth_request(int, u_int32_t, struct ssh *); 109 110 /* helper */ 111 static Authmethod *authmethod_lookup(Authctxt *, const char *); 112 static char *authmethods_get(Authctxt *authctxt); 113 114 #define MATCH_NONE 0 /* method or submethod mismatch */ 115 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 116 #define MATCH_BOTH 2 /* method and submethod match */ 117 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 118 static int list_starts_with(const char *, const char *, const char *); 119 120 char * 121 auth2_read_banner(void) 122 { 123 struct stat st; 124 char *banner = NULL; 125 size_t len, n; 126 int fd; 127 128 if ((fd = open(options.banner, O_RDONLY)) == -1) 129 return (NULL); 130 if (fstat(fd, &st) == -1) { 131 close(fd); 132 return (NULL); 133 } 134 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 135 close(fd); 136 return (NULL); 137 } 138 139 len = (size_t)st.st_size; /* truncate */ 140 banner = xmalloc(len + 1); 141 n = atomicio(read, fd, banner, len); 142 close(fd); 143 144 if (n != len) { 145 free(banner); 146 return (NULL); 147 } 148 banner[n] = '\0'; 149 150 return (banner); 151 } 152 153 static void 154 userauth_send_banner(struct ssh *ssh, const char *msg) 155 { 156 int r; 157 158 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 || 159 (r = sshpkt_put_cstring(ssh, msg)) != 0 || 160 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */ 161 (r = sshpkt_send(ssh)) != 0) 162 fatal("%s: %s", __func__, ssh_err(r)); 163 debug("%s: sent", __func__); 164 } 165 166 static void 167 userauth_banner(struct ssh *ssh) 168 { 169 char *banner = NULL; 170 171 if (options.banner == NULL) 172 return; 173 174 if ((banner = PRIVSEP(auth2_read_banner())) == NULL) 175 goto done; 176 userauth_send_banner(ssh, banner); 177 178 done: 179 free(banner); 180 } 181 182 /* 183 * loop until authctxt->success == TRUE 184 */ 185 void 186 do_authentication2(struct ssh *ssh) 187 { 188 Authctxt *authctxt = ssh->authctxt; 189 190 ssh_dispatch_init(ssh, &dispatch_protocol_error); 191 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); 192 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); 193 ssh->authctxt = NULL; 194 } 195 196 /*ARGSUSED*/ 197 static int 198 input_service_request(int type, u_int32_t seq, struct ssh *ssh) 199 { 200 Authctxt *authctxt = ssh->authctxt; 201 char *service = NULL; 202 int r, acceptit = 0; 203 204 if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 205 (r = sshpkt_get_end(ssh)) != 0) 206 goto out; 207 208 if (authctxt == NULL) 209 fatal("input_service_request: no authctxt"); 210 211 if (strcmp(service, "ssh-userauth") == 0) { 212 if (!authctxt->success) { 213 acceptit = 1; 214 /* now we can handle user-auth requests */ 215 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 216 &input_userauth_request); 217 } 218 } 219 /* XXX all other service requests are denied */ 220 221 if (acceptit) { 222 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 || 223 (r = sshpkt_put_cstring(ssh, service)) != 0 || 224 (r = sshpkt_send(ssh)) != 0 || 225 (r = ssh_packet_write_wait(ssh)) < 0) 226 goto out; 227 } else { 228 debug("bad service request %s", service); 229 ssh_packet_disconnect(ssh, "bad service request %s", service); 230 } 231 r = 0; 232 out: 233 free(service); 234 return r; 235 } 236 237 #define MIN_FAIL_DELAY_SECONDS 0.005 238 static double 239 user_specific_delay(const char *user) 240 { 241 char b[512]; 242 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 243 u_char *hash = xmalloc(len); 244 double delay; 245 246 (void)snprintf(b, sizeof b, "%llu%s", 247 (unsigned long long)options.timing_secret, user); 248 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 249 fatal("%s: ssh_digest_memory", __func__); 250 /* 0-4.2 ms of delay */ 251 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 252 freezero(hash, len); 253 debug3("%s: user specific delay %0.3lfms", __func__, delay/1000); 254 return MIN_FAIL_DELAY_SECONDS + delay; 255 } 256 257 static void 258 ensure_minimum_time_since(double start, double seconds) 259 { 260 struct timespec ts; 261 double elapsed = monotime_double() - start, req = seconds, remain; 262 263 /* if we've already passed the requested time, scale up */ 264 while ((remain = seconds - elapsed) < 0.0) 265 seconds *= 2; 266 267 ts.tv_sec = remain; 268 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; 269 debug3("%s: elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 270 __func__, elapsed*1000, remain*1000, req*1000); 271 nanosleep(&ts, NULL); 272 } 273 274 /*ARGSUSED*/ 275 static int 276 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 277 { 278 Authctxt *authctxt = ssh->authctxt; 279 Authmethod *m = NULL; 280 char *user = NULL, *service = NULL, *method = NULL, *style = NULL; 281 int r, authenticated = 0; 282 double tstart = monotime_double(); 283 284 if (authctxt == NULL) 285 fatal("input_userauth_request: no authctxt"); 286 287 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || 288 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 289 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) 290 goto out; 291 debug("userauth-request for user %s service %s method %s", user, service, method); 292 if (!log_flag) { 293 logit("SSH: Server;Ltype: Authname;Remote: %s-%d;Name: %s", 294 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), user); 295 log_flag = 1; 296 } 297 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 298 299 if ((style = strchr(user, ':')) != NULL) 300 *style++ = 0; 301 302 if (authctxt->attempt++ == 0) { 303 /* setup auth context */ 304 authctxt->pw = PRIVSEP(getpwnamallow(ssh, user)); 305 authctxt->user = xstrdup(user); 306 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 307 authctxt->valid = 1; 308 debug2("%s: setting up authctxt for %s", 309 __func__, user); 310 } else { 311 /* Invalid user, fake password information */ 312 authctxt->pw = fakepw(); 313 pfilter_notify(1); 314 } 315 #ifdef USE_PAM 316 if (options.use_pam) 317 PRIVSEP(start_pam(ssh)); 318 #endif 319 ssh_packet_set_log_preamble(ssh, "%suser %s", 320 authctxt->valid ? "authenticating " : "invalid ", user); 321 setproctitle("%s%s", authctxt->valid ? user : "unknown", 322 use_privsep ? " [net]" : ""); 323 authctxt->service = xstrdup(service); 324 authctxt->style = style ? xstrdup(style) : NULL; 325 if (use_privsep) 326 mm_inform_authserv(service, style); 327 userauth_banner(ssh); 328 if (auth2_setup_methods_lists(authctxt) != 0) 329 ssh_packet_disconnect(ssh, 330 "no authentication methods enabled"); 331 } else if (strcmp(user, authctxt->user) != 0 || 332 strcmp(service, authctxt->service) != 0) { 333 ssh_packet_disconnect(ssh, "Change of username or service " 334 "not allowed: (%s,%s) -> (%s,%s)", 335 authctxt->user, authctxt->service, user, service); 336 } 337 /* reset state */ 338 auth2_challenge_stop(ssh); 339 340 #ifdef GSSAPI 341 /* XXX move to auth2_gssapi_stop() */ 342 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 343 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 344 #endif 345 346 auth2_authctxt_reset_info(authctxt); 347 authctxt->postponed = 0; 348 authctxt->server_caused_failure = 0; 349 350 /* try to authenticate user */ 351 m = authmethod_lookup(authctxt, method); 352 if (m != NULL && authctxt->failures < options.max_authtries) { 353 debug2("input_userauth_request: try method %s", method); 354 authenticated = m->userauth(ssh); 355 } 356 if (!authctxt->authenticated) 357 ensure_minimum_time_since(tstart, 358 user_specific_delay(authctxt->user)); 359 userauth_finish(ssh, authenticated, method, NULL); 360 r = 0; 361 out: 362 free(service); 363 free(user); 364 free(method); 365 return r; 366 } 367 368 void 369 userauth_finish(struct ssh *ssh, int authenticated, const char *method, 370 const char *submethod) 371 { 372 Authctxt *authctxt = ssh->authctxt; 373 char *methods; 374 int r, partial = 0; 375 376 if (!authctxt->valid && authenticated) 377 fatal("INTERNAL ERROR: authenticated invalid user %s", 378 authctxt->user); 379 if (authenticated && authctxt->postponed) 380 fatal("INTERNAL ERROR: authenticated and postponed"); 381 382 /* Special handling for root */ 383 if (authenticated && authctxt->pw->pw_uid == 0 && 384 !auth_root_allowed(ssh, method)) { 385 authenticated = 0; 386 #ifdef SSH_AUDIT_EVENTS 387 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED)); 388 #endif 389 } 390 391 #ifdef USE_PAM 392 if (options.use_pam && authenticated) { 393 if (!PRIVSEP(do_pam_account())) { 394 /* if PAM returned a message, send it to the user */ 395 if (sshbuf_len(loginmsg) > 0) { 396 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0) 397 fatal("%s: buffer error: %s", 398 __func__, ssh_err(r)); 399 userauth_send_banner(ssh, 400 (const char *)sshbuf_ptr(loginmsg)); 401 if ((r = ssh_packet_write_wait(ssh)) < 0) { 402 sshpkt_fatal(ssh, r, 403 "%s: send PAM banner", __func__); 404 } 405 } 406 fatal("Access denied for user %s by PAM account " 407 "configuration", authctxt->user); 408 } 409 } 410 #endif 411 412 if (authenticated && options.num_auth_methods != 0) { 413 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 414 authenticated = 0; 415 partial = 1; 416 } 417 } 418 419 /* Log before sending the reply */ 420 auth_log(ssh, authenticated, partial, method, submethod); 421 422 /* Update information exposed to session */ 423 if (authenticated || partial) 424 auth2_update_session_info(authctxt, method, submethod); 425 426 if (authctxt->postponed) 427 return; 428 429 if (authenticated == 1) { 430 /* turn off userauth */ 431 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 432 &dispatch_protocol_ignore); 433 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 434 (r = sshpkt_send(ssh)) != 0 || 435 (r = ssh_packet_write_wait(ssh)) < 0) 436 fatal("%s: %s", __func__, ssh_err(r)); 437 /* now we can break out */ 438 authctxt->success = 1; 439 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 440 } else { 441 /* Allow initial try of "none" auth without failure penalty */ 442 if (!partial && !authctxt->server_caused_failure && 443 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) { 444 authctxt->failures++; 445 pfilter_notify(1); 446 } 447 if (authctxt->failures >= options.max_authtries) 448 auth_maxtries_exceeded(ssh); 449 methods = authmethods_get(authctxt); 450 debug3("%s: failure partial=%d next methods=\"%s\"", __func__, 451 partial, methods); 452 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 453 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 454 (r = sshpkt_put_u8(ssh, partial)) != 0 || 455 (r = sshpkt_send(ssh)) != 0 || 456 (r = ssh_packet_write_wait(ssh)) < 0) 457 fatal("%s: %s", __func__, ssh_err(r)); 458 free(methods); 459 } 460 } 461 462 /* 463 * Checks whether method is allowed by at least one AuthenticationMethods 464 * methods list. Returns 1 if allowed, or no methods lists configured. 465 * 0 otherwise. 466 */ 467 int 468 auth2_method_allowed(Authctxt *authctxt, const char *method, 469 const char *submethod) 470 { 471 u_int i; 472 473 /* 474 * NB. authctxt->num_auth_methods might be zero as a result of 475 * auth2_setup_methods_lists(), so check the configuration. 476 */ 477 if (options.num_auth_methods == 0) 478 return 1; 479 for (i = 0; i < authctxt->num_auth_methods; i++) { 480 if (list_starts_with(authctxt->auth_methods[i], method, 481 submethod) != MATCH_NONE) 482 return 1; 483 } 484 return 0; 485 } 486 487 static char * 488 authmethods_get(Authctxt *authctxt) 489 { 490 struct sshbuf *b; 491 char *list; 492 int i, r; 493 494 if ((b = sshbuf_new()) == NULL) 495 fatal("%s: sshbuf_new failed", __func__); 496 for (i = 0; authmethods[i] != NULL; i++) { 497 if (strcmp(authmethods[i]->name, "none") == 0) 498 continue; 499 if (authmethods[i]->enabled == NULL || 500 *(authmethods[i]->enabled) == 0) 501 continue; 502 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 503 NULL)) 504 continue; 505 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 506 authmethods[i]->name)) != 0) 507 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 508 } 509 if ((list = sshbuf_dup_string(b)) == NULL) 510 fatal("%s: sshbuf_dup_string failed", __func__); 511 sshbuf_free(b); 512 return list; 513 } 514 515 static Authmethod * 516 authmethod_lookup(Authctxt *authctxt, const char *name) 517 { 518 int i; 519 520 if (name != NULL) 521 for (i = 0; authmethods[i] != NULL; i++) 522 if (authmethods[i]->enabled != NULL && 523 *(authmethods[i]->enabled) != 0 && 524 strcmp(name, authmethods[i]->name) == 0 && 525 auth2_method_allowed(authctxt, 526 authmethods[i]->name, NULL)) 527 return authmethods[i]; 528 debug2("Unrecognized authentication method name: %s", 529 name ? name : "NULL"); 530 return NULL; 531 } 532 533 /* 534 * Check a comma-separated list of methods for validity. Is need_enable is 535 * non-zero, then also require that the methods are enabled. 536 * Returns 0 on success or -1 if the methods list is invalid. 537 */ 538 int 539 auth2_methods_valid(const char *_methods, int need_enable) 540 { 541 char *methods, *omethods, *method, *p; 542 u_int i, found; 543 int ret = -1; 544 545 if (*_methods == '\0') { 546 error("empty authentication method list"); 547 return -1; 548 } 549 omethods = methods = xstrdup(_methods); 550 while ((method = strsep(&methods, ",")) != NULL) { 551 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 552 if ((p = strchr(method, ':')) != NULL) 553 *p = '\0'; 554 if (strcmp(method, authmethods[i]->name) != 0) 555 continue; 556 if (need_enable) { 557 if (authmethods[i]->enabled == NULL || 558 *(authmethods[i]->enabled) == 0) { 559 error("Disabled method \"%s\" in " 560 "AuthenticationMethods list \"%s\"", 561 method, _methods); 562 goto out; 563 } 564 } 565 found = 1; 566 break; 567 } 568 if (!found) { 569 error("Unknown authentication method \"%s\" in list", 570 method); 571 goto out; 572 } 573 } 574 ret = 0; 575 out: 576 free(omethods); 577 return ret; 578 } 579 580 /* 581 * Prune the AuthenticationMethods supplied in the configuration, removing 582 * any methods lists that include disabled methods. Note that this might 583 * leave authctxt->num_auth_methods == 0, even when multiple required auth 584 * has been requested. For this reason, all tests for whether multiple is 585 * enabled should consult options.num_auth_methods directly. 586 */ 587 int 588 auth2_setup_methods_lists(Authctxt *authctxt) 589 { 590 u_int i; 591 592 /* First, normalise away the "any" pseudo-method */ 593 if (options.num_auth_methods == 1 && 594 strcmp(options.auth_methods[0], "any") == 0) { 595 free(options.auth_methods[0]); 596 options.auth_methods[0] = NULL; 597 options.num_auth_methods = 0; 598 } 599 600 if (options.num_auth_methods == 0) 601 return 0; 602 debug3("%s: checking methods", __func__); 603 authctxt->auth_methods = xcalloc(options.num_auth_methods, 604 sizeof(*authctxt->auth_methods)); 605 authctxt->num_auth_methods = 0; 606 for (i = 0; i < options.num_auth_methods; i++) { 607 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 608 logit("Authentication methods list \"%s\" contains " 609 "disabled method, skipping", 610 options.auth_methods[i]); 611 continue; 612 } 613 debug("authentication methods list %d: %s", 614 authctxt->num_auth_methods, options.auth_methods[i]); 615 authctxt->auth_methods[authctxt->num_auth_methods++] = 616 xstrdup(options.auth_methods[i]); 617 } 618 if (authctxt->num_auth_methods == 0) { 619 error("No AuthenticationMethods left after eliminating " 620 "disabled methods"); 621 return -1; 622 } 623 return 0; 624 } 625 626 static int 627 list_starts_with(const char *methods, const char *method, 628 const char *submethod) 629 { 630 size_t l = strlen(method); 631 int match; 632 const char *p; 633 634 if (strncmp(methods, method, l) != 0) 635 return MATCH_NONE; 636 p = methods + l; 637 match = MATCH_METHOD; 638 if (*p == ':') { 639 if (!submethod) 640 return MATCH_PARTIAL; 641 l = strlen(submethod); 642 p += 1; 643 if (strncmp(submethod, p, l)) 644 return MATCH_NONE; 645 p += l; 646 match = MATCH_BOTH; 647 } 648 if (*p != ',' && *p != '\0') 649 return MATCH_NONE; 650 return match; 651 } 652 653 /* 654 * Remove method from the start of a comma-separated list of methods. 655 * Returns 0 if the list of methods did not start with that method or 1 656 * if it did. 657 */ 658 static int 659 remove_method(char **methods, const char *method, const char *submethod) 660 { 661 char *omethods = *methods, *p; 662 size_t l = strlen(method); 663 int match; 664 665 match = list_starts_with(omethods, method, submethod); 666 if (match != MATCH_METHOD && match != MATCH_BOTH) 667 return 0; 668 p = omethods + l; 669 if (submethod && match == MATCH_BOTH) 670 p += 1 + strlen(submethod); /* include colon */ 671 if (*p == ',') 672 p++; 673 *methods = xstrdup(p); 674 free(omethods); 675 return 1; 676 } 677 678 /* 679 * Called after successful authentication. Will remove the successful method 680 * from the start of each list in which it occurs. If it was the last method 681 * in any list, then authentication is deemed successful. 682 * Returns 1 if the method completed any authentication list or 0 otherwise. 683 */ 684 int 685 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 686 const char *submethod) 687 { 688 u_int i, found = 0; 689 690 debug3("%s: updating methods list after \"%s\"", __func__, method); 691 for (i = 0; i < authctxt->num_auth_methods; i++) { 692 if (!remove_method(&(authctxt->auth_methods[i]), method, 693 submethod)) 694 continue; 695 found = 1; 696 if (*authctxt->auth_methods[i] == '\0') { 697 debug2("authentication methods list %d complete", i); 698 return 1; 699 } 700 debug3("authentication methods list %d remaining: \"%s\"", 701 i, authctxt->auth_methods[i]); 702 } 703 /* This should not happen, but would be bad if it did */ 704 if (!found) 705 fatal("%s: method not in AuthenticationMethods", __func__); 706 return 0; 707 } 708 709 /* Reset method-specific information */ 710 void auth2_authctxt_reset_info(Authctxt *authctxt) 711 { 712 sshkey_free(authctxt->auth_method_key); 713 free(authctxt->auth_method_info); 714 authctxt->auth_method_key = NULL; 715 authctxt->auth_method_info = NULL; 716 } 717 718 /* Record auth method-specific information for logs */ 719 void 720 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 721 { 722 va_list ap; 723 int i; 724 725 free(authctxt->auth_method_info); 726 authctxt->auth_method_info = NULL; 727 728 va_start(ap, fmt); 729 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 730 va_end(ap); 731 732 if (i == -1) 733 fatal("%s: vasprintf failed", __func__); 734 } 735 736 /* 737 * Records a public key used in authentication. This is used for logging 738 * and to ensure that the same key is not subsequently accepted again for 739 * multiple authentication. 740 */ 741 void 742 auth2_record_key(Authctxt *authctxt, int authenticated, 743 const struct sshkey *key) 744 { 745 struct sshkey **tmp, *dup; 746 int r; 747 748 if ((r = sshkey_from_private(key, &dup)) != 0) 749 fatal("%s: copy key: %s", __func__, ssh_err(r)); 750 sshkey_free(authctxt->auth_method_key); 751 authctxt->auth_method_key = dup; 752 753 if (!authenticated) 754 return; 755 756 /* If authenticated, make sure we don't accept this key again */ 757 if ((r = sshkey_from_private(key, &dup)) != 0) 758 fatal("%s: copy key: %s", __func__, ssh_err(r)); 759 if (authctxt->nprev_keys >= INT_MAX || 760 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 761 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 762 fatal("%s: reallocarray failed", __func__); 763 authctxt->prev_keys = tmp; 764 authctxt->prev_keys[authctxt->nprev_keys] = dup; 765 authctxt->nprev_keys++; 766 767 } 768 769 /* Checks whether a key has already been previously used for authentication */ 770 int 771 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 772 { 773 u_int i; 774 char *fp; 775 776 for (i = 0; i < authctxt->nprev_keys; i++) { 777 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 778 fp = sshkey_fingerprint(authctxt->prev_keys[i], 779 options.fingerprint_hash, SSH_FP_DEFAULT); 780 debug3("%s: key already used: %s %s", __func__, 781 sshkey_type(authctxt->prev_keys[i]), 782 fp == NULL ? "UNKNOWN" : fp); 783 free(fp); 784 return 1; 785 } 786 } 787 return 0; 788 } 789 790 /* 791 * Updates authctxt->session_info with details of authentication. Should be 792 * whenever an authentication method succeeds. 793 */ 794 void 795 auth2_update_session_info(Authctxt *authctxt, const char *method, 796 const char *submethod) 797 { 798 int r; 799 800 if (authctxt->session_info == NULL) { 801 if ((authctxt->session_info = sshbuf_new()) == NULL) 802 fatal("%s: sshbuf_new", __func__); 803 } 804 805 /* Append method[/submethod] */ 806 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 807 method, submethod == NULL ? "" : "/", 808 submethod == NULL ? "" : submethod)) != 0) 809 fatal("%s: append method: %s", __func__, ssh_err(r)); 810 811 /* Append key if present */ 812 if (authctxt->auth_method_key != NULL) { 813 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 814 (r = sshkey_format_text(authctxt->auth_method_key, 815 authctxt->session_info)) != 0) 816 fatal("%s: append key: %s", __func__, ssh_err(r)); 817 } 818 819 if (authctxt->auth_method_info != NULL) { 820 /* Ensure no ambiguity here */ 821 if (strchr(authctxt->auth_method_info, '\n') != NULL) 822 fatal("%s: auth_method_info contains \\n", __func__); 823 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 824 (r = sshbuf_putf(authctxt->session_info, "%s", 825 authctxt->auth_method_info)) != 0) { 826 fatal("%s: append method info: %s", 827 __func__, ssh_err(r)); 828 } 829 } 830 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 831 fatal("%s: append: %s", __func__, ssh_err(r)); 832 } 833 834