1 /* $OpenBSD: auth2.c,v 1.164 2022/02/23 11:18:13 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 "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 #include "blacklist_client.h" 57 #ifdef GSSAPI 58 #include "ssh-gss.h" 59 #endif 60 #include "monitor_wrap.h" 61 #include "digest.h" 62 63 /* import */ 64 extern ServerOptions options; 65 extern struct sshbuf *loginmsg; 66 67 /* methods */ 68 69 extern Authmethod method_none; 70 extern Authmethod method_pubkey; 71 extern Authmethod method_passwd; 72 extern Authmethod method_kbdint; 73 extern Authmethod method_hostbased; 74 #ifdef GSSAPI 75 extern Authmethod method_gssapi; 76 #endif 77 78 Authmethod *authmethods[] = { 79 &method_none, 80 &method_pubkey, 81 #ifdef GSSAPI 82 &method_gssapi, 83 #endif 84 &method_passwd, 85 &method_kbdint, 86 &method_hostbased, 87 NULL 88 }; 89 90 /* protocol */ 91 92 static int input_service_request(int, u_int32_t, struct ssh *); 93 static int input_userauth_request(int, u_int32_t, struct ssh *); 94 95 /* helper */ 96 static Authmethod *authmethod_byname(const char *); 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_fr(r, "send packet"); 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_f("ssh_digest_memory"); 236 /* 0-4.2 ms of delay */ 237 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 238 freezero(hash, len); 239 debug3_f("user specific delay %0.3lfms", 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_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 256 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 >= 1024) 284 auth_maxtries_exceeded(ssh); 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_f("setting up authctxt for %s", user); 292 } else { 293 authctxt->valid = 0; 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, method); 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 *packet_method, 355 const char *submethod) 356 { 357 Authctxt *authctxt = ssh->authctxt; 358 Authmethod *m = NULL; 359 const char *method = packet_method; 360 char *methods; 361 int r, partial = 0; 362 363 if (authenticated) { 364 if (!authctxt->valid) { 365 fatal("INTERNAL ERROR: authenticated invalid user %s", 366 authctxt->user); 367 } 368 if (authctxt->postponed) 369 fatal("INTERNAL ERROR: authenticated and postponed"); 370 /* prefer primary authmethod name to possible synonym */ 371 if ((m = authmethod_byname(method)) == NULL) 372 fatal("INTERNAL ERROR: bad method %s", method); 373 method = m->name; 374 } 375 376 /* Special handling for root */ 377 if (authenticated && authctxt->pw->pw_uid == 0 && 378 !auth_root_allowed(ssh, method)) { 379 authenticated = 0; 380 #ifdef SSH_AUDIT_EVENTS 381 PRIVSEP(audit_event(ssh, SSH_LOGIN_ROOT_DENIED)); 382 #endif 383 } 384 385 if (authenticated && options.num_auth_methods != 0) { 386 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 387 authenticated = 0; 388 partial = 1; 389 } 390 } 391 392 /* Log before sending the reply */ 393 auth_log(ssh, authenticated, partial, method, submethod); 394 395 /* Update information exposed to session */ 396 if (authenticated || partial) 397 auth2_update_session_info(authctxt, method, submethod); 398 399 if (authctxt->postponed) 400 return; 401 402 #ifdef USE_PAM 403 if (options.use_pam && authenticated) { 404 int r, success = PRIVSEP(do_pam_account()); 405 406 /* If PAM returned a message, send it to the user. */ 407 if (sshbuf_len(loginmsg) > 0) { 408 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0) 409 fatal("%s: buffer error: %s", 410 __func__, ssh_err(r)); 411 userauth_send_banner(ssh, sshbuf_ptr(loginmsg)); 412 if ((r = ssh_packet_write_wait(ssh)) != 0) { 413 sshpkt_fatal(ssh, r, 414 "%s: send PAM banner", __func__); 415 } 416 } 417 if (!success) { 418 fatal("Access denied for user %s by PAM account " 419 "configuration", authctxt->user); 420 } 421 } 422 #endif 423 424 if (authenticated == 1) { 425 /* turn off userauth */ 426 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 427 &dispatch_protocol_ignore); 428 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 429 (r = sshpkt_send(ssh)) != 0 || 430 (r = ssh_packet_write_wait(ssh)) != 0) 431 fatal_fr(r, "send success packet"); 432 /* now we can break out */ 433 authctxt->success = 1; 434 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 435 } else { 436 /* Allow initial try of "none" auth without failure penalty */ 437 if (!partial && !authctxt->server_caused_failure && 438 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) { 439 authctxt->failures++; 440 BLACKLIST_NOTIFY(ssh, BLACKLIST_AUTH_FAIL, "ssh"); 441 } 442 if (authctxt->failures >= options.max_authtries) { 443 #ifdef SSH_AUDIT_EVENTS 444 PRIVSEP(audit_event(ssh, SSH_LOGIN_EXCEED_MAXTRIES)); 445 #endif 446 auth_maxtries_exceeded(ssh); 447 } 448 methods = authmethods_get(authctxt); 449 debug3_f("failure partial=%d next methods=\"%s\"", 450 partial, methods); 451 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 452 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 453 (r = sshpkt_put_u8(ssh, partial)) != 0 || 454 (r = sshpkt_send(ssh)) != 0 || 455 (r = ssh_packet_write_wait(ssh)) != 0) 456 fatal_fr(r, "send failure packet"); 457 free(methods); 458 } 459 } 460 461 /* 462 * Checks whether method is allowed by at least one AuthenticationMethods 463 * methods list. Returns 1 if allowed, or no methods lists configured. 464 * 0 otherwise. 465 */ 466 int 467 auth2_method_allowed(Authctxt *authctxt, const char *method, 468 const char *submethod) 469 { 470 u_int i; 471 472 /* 473 * NB. authctxt->num_auth_methods might be zero as a result of 474 * auth2_setup_methods_lists(), so check the configuration. 475 */ 476 if (options.num_auth_methods == 0) 477 return 1; 478 for (i = 0; i < authctxt->num_auth_methods; i++) { 479 if (list_starts_with(authctxt->auth_methods[i], method, 480 submethod) != MATCH_NONE) 481 return 1; 482 } 483 return 0; 484 } 485 486 static char * 487 authmethods_get(Authctxt *authctxt) 488 { 489 struct sshbuf *b; 490 char *list; 491 int i, r; 492 493 if ((b = sshbuf_new()) == NULL) 494 fatal_f("sshbuf_new failed"); 495 for (i = 0; authmethods[i] != NULL; i++) { 496 if (strcmp(authmethods[i]->name, "none") == 0) 497 continue; 498 if (authmethods[i]->enabled == NULL || 499 *(authmethods[i]->enabled) == 0) 500 continue; 501 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 502 NULL)) 503 continue; 504 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 505 authmethods[i]->name)) != 0) 506 fatal_fr(r, "buffer error"); 507 } 508 if ((list = sshbuf_dup_string(b)) == NULL) 509 fatal_f("sshbuf_dup_string failed"); 510 sshbuf_free(b); 511 return list; 512 } 513 514 static Authmethod * 515 authmethod_byname(const char *name) 516 { 517 int i; 518 519 if (name == NULL) 520 fatal_f("NULL authentication method name"); 521 for (i = 0; authmethods[i] != NULL; i++) { 522 if (strcmp(name, authmethods[i]->name) == 0 || 523 (authmethods[i]->synonym != NULL && 524 strcmp(name, authmethods[i]->synonym) == 0)) 525 return authmethods[i]; 526 } 527 debug_f("unrecognized authentication method name: %s", name); 528 return NULL; 529 } 530 531 static Authmethod * 532 authmethod_lookup(Authctxt *authctxt, const char *name) 533 { 534 Authmethod *method; 535 536 if ((method = authmethod_byname(name)) == NULL) 537 return NULL; 538 539 if (method->enabled == NULL || *(method->enabled) == 0) { 540 debug3_f("method %s not enabled", name); 541 return NULL; 542 } 543 if (!auth2_method_allowed(authctxt, method->name, NULL)) { 544 debug3_f("method %s not allowed " 545 "by AuthenticationMethods", name); 546 return NULL; 547 } 548 return method; 549 } 550 551 /* 552 * Check a comma-separated list of methods for validity. Is need_enable is 553 * non-zero, then also require that the methods are enabled. 554 * Returns 0 on success or -1 if the methods list is invalid. 555 */ 556 int 557 auth2_methods_valid(const char *_methods, int need_enable) 558 { 559 char *methods, *omethods, *method, *p; 560 u_int i, found; 561 int ret = -1; 562 563 if (*_methods == '\0') { 564 error("empty authentication method list"); 565 return -1; 566 } 567 omethods = methods = xstrdup(_methods); 568 while ((method = strsep(&methods, ",")) != NULL) { 569 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 570 if ((p = strchr(method, ':')) != NULL) 571 *p = '\0'; 572 if (strcmp(method, authmethods[i]->name) != 0) 573 continue; 574 if (need_enable) { 575 if (authmethods[i]->enabled == NULL || 576 *(authmethods[i]->enabled) == 0) { 577 error("Disabled method \"%s\" in " 578 "AuthenticationMethods list \"%s\"", 579 method, _methods); 580 goto out; 581 } 582 } 583 found = 1; 584 break; 585 } 586 if (!found) { 587 error("Unknown authentication method \"%s\" in list", 588 method); 589 goto out; 590 } 591 } 592 ret = 0; 593 out: 594 free(omethods); 595 return ret; 596 } 597 598 /* 599 * Prune the AuthenticationMethods supplied in the configuration, removing 600 * any methods lists that include disabled methods. Note that this might 601 * leave authctxt->num_auth_methods == 0, even when multiple required auth 602 * has been requested. For this reason, all tests for whether multiple is 603 * enabled should consult options.num_auth_methods directly. 604 */ 605 int 606 auth2_setup_methods_lists(Authctxt *authctxt) 607 { 608 u_int i; 609 610 /* First, normalise away the "any" pseudo-method */ 611 if (options.num_auth_methods == 1 && 612 strcmp(options.auth_methods[0], "any") == 0) { 613 free(options.auth_methods[0]); 614 options.auth_methods[0] = NULL; 615 options.num_auth_methods = 0; 616 } 617 618 if (options.num_auth_methods == 0) 619 return 0; 620 debug3_f("checking methods"); 621 authctxt->auth_methods = xcalloc(options.num_auth_methods, 622 sizeof(*authctxt->auth_methods)); 623 authctxt->num_auth_methods = 0; 624 for (i = 0; i < options.num_auth_methods; i++) { 625 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 626 logit("Authentication methods list \"%s\" contains " 627 "disabled method, skipping", 628 options.auth_methods[i]); 629 continue; 630 } 631 debug("authentication methods list %d: %s", 632 authctxt->num_auth_methods, options.auth_methods[i]); 633 authctxt->auth_methods[authctxt->num_auth_methods++] = 634 xstrdup(options.auth_methods[i]); 635 } 636 if (authctxt->num_auth_methods == 0) { 637 error("No AuthenticationMethods left after eliminating " 638 "disabled methods"); 639 return -1; 640 } 641 return 0; 642 } 643 644 static int 645 list_starts_with(const char *methods, const char *method, 646 const char *submethod) 647 { 648 size_t l = strlen(method); 649 int match; 650 const char *p; 651 652 if (strncmp(methods, method, l) != 0) 653 return MATCH_NONE; 654 p = methods + l; 655 match = MATCH_METHOD; 656 if (*p == ':') { 657 if (!submethod) 658 return MATCH_PARTIAL; 659 l = strlen(submethod); 660 p += 1; 661 if (strncmp(submethod, p, l)) 662 return MATCH_NONE; 663 p += l; 664 match = MATCH_BOTH; 665 } 666 if (*p != ',' && *p != '\0') 667 return MATCH_NONE; 668 return match; 669 } 670 671 /* 672 * Remove method from the start of a comma-separated list of methods. 673 * Returns 0 if the list of methods did not start with that method or 1 674 * if it did. 675 */ 676 static int 677 remove_method(char **methods, const char *method, const char *submethod) 678 { 679 char *omethods = *methods, *p; 680 size_t l = strlen(method); 681 int match; 682 683 match = list_starts_with(omethods, method, submethod); 684 if (match != MATCH_METHOD && match != MATCH_BOTH) 685 return 0; 686 p = omethods + l; 687 if (submethod && match == MATCH_BOTH) 688 p += 1 + strlen(submethod); /* include colon */ 689 if (*p == ',') 690 p++; 691 *methods = xstrdup(p); 692 free(omethods); 693 return 1; 694 } 695 696 /* 697 * Called after successful authentication. Will remove the successful method 698 * from the start of each list in which it occurs. If it was the last method 699 * in any list, then authentication is deemed successful. 700 * Returns 1 if the method completed any authentication list or 0 otherwise. 701 */ 702 int 703 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 704 const char *submethod) 705 { 706 u_int i, found = 0; 707 708 debug3_f("updating methods list after \"%s\"", method); 709 for (i = 0; i < authctxt->num_auth_methods; i++) { 710 if (!remove_method(&(authctxt->auth_methods[i]), method, 711 submethod)) 712 continue; 713 found = 1; 714 if (*authctxt->auth_methods[i] == '\0') { 715 debug2("authentication methods list %d complete", i); 716 return 1; 717 } 718 debug3("authentication methods list %d remaining: \"%s\"", 719 i, authctxt->auth_methods[i]); 720 } 721 /* This should not happen, but would be bad if it did */ 722 if (!found) 723 fatal_f("method not in AuthenticationMethods"); 724 return 0; 725 } 726 727 /* Reset method-specific information */ 728 void auth2_authctxt_reset_info(Authctxt *authctxt) 729 { 730 sshkey_free(authctxt->auth_method_key); 731 free(authctxt->auth_method_info); 732 authctxt->auth_method_key = NULL; 733 authctxt->auth_method_info = NULL; 734 } 735 736 /* Record auth method-specific information for logs */ 737 void 738 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 739 { 740 va_list ap; 741 int i; 742 743 free(authctxt->auth_method_info); 744 authctxt->auth_method_info = NULL; 745 746 va_start(ap, fmt); 747 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 748 va_end(ap); 749 750 if (i == -1) 751 fatal_f("vasprintf failed"); 752 } 753 754 /* 755 * Records a public key used in authentication. This is used for logging 756 * and to ensure that the same key is not subsequently accepted again for 757 * multiple authentication. 758 */ 759 void 760 auth2_record_key(Authctxt *authctxt, int authenticated, 761 const struct sshkey *key) 762 { 763 struct sshkey **tmp, *dup; 764 int r; 765 766 if ((r = sshkey_from_private(key, &dup)) != 0) 767 fatal_fr(r, "copy key"); 768 sshkey_free(authctxt->auth_method_key); 769 authctxt->auth_method_key = dup; 770 771 if (!authenticated) 772 return; 773 774 /* If authenticated, make sure we don't accept this key again */ 775 if ((r = sshkey_from_private(key, &dup)) != 0) 776 fatal_fr(r, "copy key"); 777 if (authctxt->nprev_keys >= INT_MAX || 778 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 779 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 780 fatal_f("reallocarray failed"); 781 authctxt->prev_keys = tmp; 782 authctxt->prev_keys[authctxt->nprev_keys] = dup; 783 authctxt->nprev_keys++; 784 785 } 786 787 /* Checks whether a key has already been previously used for authentication */ 788 int 789 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 790 { 791 u_int i; 792 char *fp; 793 794 for (i = 0; i < authctxt->nprev_keys; i++) { 795 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 796 fp = sshkey_fingerprint(authctxt->prev_keys[i], 797 options.fingerprint_hash, SSH_FP_DEFAULT); 798 debug3_f("key already used: %s %s", 799 sshkey_type(authctxt->prev_keys[i]), 800 fp == NULL ? "UNKNOWN" : fp); 801 free(fp); 802 return 1; 803 } 804 } 805 return 0; 806 } 807 808 /* 809 * Updates authctxt->session_info with details of authentication. Should be 810 * whenever an authentication method succeeds. 811 */ 812 void 813 auth2_update_session_info(Authctxt *authctxt, const char *method, 814 const char *submethod) 815 { 816 int r; 817 818 if (authctxt->session_info == NULL) { 819 if ((authctxt->session_info = sshbuf_new()) == NULL) 820 fatal_f("sshbuf_new"); 821 } 822 823 /* Append method[/submethod] */ 824 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 825 method, submethod == NULL ? "" : "/", 826 submethod == NULL ? "" : submethod)) != 0) 827 fatal_fr(r, "append method"); 828 829 /* Append key if present */ 830 if (authctxt->auth_method_key != NULL) { 831 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 832 (r = sshkey_format_text(authctxt->auth_method_key, 833 authctxt->session_info)) != 0) 834 fatal_fr(r, "append key"); 835 } 836 837 if (authctxt->auth_method_info != NULL) { 838 /* Ensure no ambiguity here */ 839 if (strchr(authctxt->auth_method_info, '\n') != NULL) 840 fatal_f("auth_method_info contains \\n"); 841 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 842 (r = sshbuf_putf(authctxt->session_info, "%s", 843 authctxt->auth_method_info)) != 0) { 844 fatal_fr(r, "append method info"); 845 } 846 } 847 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 848 fatal_fr(r, "append"); 849 } 850 851