1 /* $OpenBSD: auth2.c,v 1.166 2023/03/08 04:43:12 guenther 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 "sshkey.h" 50 #include "hostfile.h" 51 #include "auth.h" 52 #include "dispatch.h" 53 #include "pathnames.h" 54 #include "ssherr.h" 55 #include "blacklist_client.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 struct sshbuf *loginmsg; 65 66 /* methods */ 67 68 extern Authmethod method_none; 69 extern Authmethod method_pubkey; 70 extern Authmethod method_passwd; 71 extern Authmethod method_kbdint; 72 extern Authmethod method_hostbased; 73 #ifdef GSSAPI 74 extern Authmethod method_gssapi; 75 #endif 76 77 Authmethod *authmethods[] = { 78 &method_none, 79 &method_pubkey, 80 #ifdef GSSAPI 81 &method_gssapi, 82 #endif 83 &method_passwd, 84 &method_kbdint, 85 &method_hostbased, 86 NULL 87 }; 88 89 /* protocol */ 90 91 static int input_service_request(int, u_int32_t, struct ssh *); 92 static int input_userauth_request(int, u_int32_t, struct ssh *); 93 94 /* helper */ 95 static Authmethod *authmethod_byname(const char *); 96 static Authmethod *authmethod_lookup(Authctxt *, const char *); 97 static char *authmethods_get(Authctxt *authctxt); 98 99 #define MATCH_NONE 0 /* method or submethod mismatch */ 100 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 101 #define MATCH_BOTH 2 /* method and submethod match */ 102 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 103 static int list_starts_with(const char *, const char *, const char *); 104 105 char * 106 auth2_read_banner(void) 107 { 108 struct stat st; 109 char *banner = NULL; 110 size_t len, n; 111 int fd; 112 113 if ((fd = open(options.banner, O_RDONLY)) == -1) 114 return (NULL); 115 if (fstat(fd, &st) == -1) { 116 close(fd); 117 return (NULL); 118 } 119 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 120 close(fd); 121 return (NULL); 122 } 123 124 len = (size_t)st.st_size; /* truncate */ 125 banner = xmalloc(len + 1); 126 n = atomicio(read, fd, banner, len); 127 close(fd); 128 129 if (n != len) { 130 free(banner); 131 return (NULL); 132 } 133 banner[n] = '\0'; 134 135 return (banner); 136 } 137 138 static void 139 userauth_send_banner(struct ssh *ssh, const char *msg) 140 { 141 int r; 142 143 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 || 144 (r = sshpkt_put_cstring(ssh, msg)) != 0 || 145 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */ 146 (r = sshpkt_send(ssh)) != 0) 147 fatal_fr(r, "send packet"); 148 debug("%s: sent", __func__); 149 } 150 151 static void 152 userauth_banner(struct ssh *ssh) 153 { 154 char *banner = NULL; 155 156 if (options.banner == NULL) 157 return; 158 159 if ((banner = PRIVSEP(auth2_read_banner())) == NULL) 160 goto done; 161 userauth_send_banner(ssh, banner); 162 163 done: 164 free(banner); 165 } 166 167 /* 168 * loop until authctxt->success == TRUE 169 */ 170 void 171 do_authentication2(struct ssh *ssh) 172 { 173 Authctxt *authctxt = ssh->authctxt; 174 175 ssh_dispatch_init(ssh, &dispatch_protocol_error); 176 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); 177 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); 178 ssh->authctxt = NULL; 179 } 180 181 static int 182 input_service_request(int type, u_int32_t seq, struct ssh *ssh) 183 { 184 Authctxt *authctxt = ssh->authctxt; 185 char *service = NULL; 186 int r, acceptit = 0; 187 188 if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 189 (r = sshpkt_get_end(ssh)) != 0) 190 goto out; 191 192 if (authctxt == NULL) 193 fatal("input_service_request: no authctxt"); 194 195 if (strcmp(service, "ssh-userauth") == 0) { 196 if (!authctxt->success) { 197 acceptit = 1; 198 /* now we can handle user-auth requests */ 199 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 200 &input_userauth_request); 201 } 202 } 203 /* XXX all other service requests are denied */ 204 205 if (acceptit) { 206 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 || 207 (r = sshpkt_put_cstring(ssh, service)) != 0 || 208 (r = sshpkt_send(ssh)) != 0 || 209 (r = ssh_packet_write_wait(ssh)) != 0) 210 goto out; 211 } else { 212 debug("bad service request %s", service); 213 ssh_packet_disconnect(ssh, "bad service request %s", service); 214 } 215 r = 0; 216 out: 217 free(service); 218 return r; 219 } 220 221 #define MIN_FAIL_DELAY_SECONDS 0.005 222 static double 223 user_specific_delay(const char *user) 224 { 225 char b[512]; 226 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 227 u_char *hash = xmalloc(len); 228 double delay; 229 230 (void)snprintf(b, sizeof b, "%llu%s", 231 (unsigned long long)options.timing_secret, user); 232 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 233 fatal_f("ssh_digest_memory"); 234 /* 0-4.2 ms of delay */ 235 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 236 freezero(hash, len); 237 debug3_f("user specific delay %0.3lfms", delay/1000); 238 return MIN_FAIL_DELAY_SECONDS + delay; 239 } 240 241 static void 242 ensure_minimum_time_since(double start, double seconds) 243 { 244 struct timespec ts; 245 double elapsed = monotime_double() - start, req = seconds, remain; 246 247 /* if we've already passed the requested time, scale up */ 248 while ((remain = seconds - elapsed) < 0.0) 249 seconds *= 2; 250 251 ts.tv_sec = remain; 252 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; 253 debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 254 elapsed*1000, remain*1000, req*1000); 255 nanosleep(&ts, NULL); 256 } 257 258 static int 259 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 260 { 261 Authctxt *authctxt = ssh->authctxt; 262 Authmethod *m = NULL; 263 char *user = NULL, *service = NULL, *method = NULL, *style = NULL; 264 int r, authenticated = 0; 265 double tstart = monotime_double(); 266 267 if (authctxt == NULL) 268 fatal("input_userauth_request: no authctxt"); 269 270 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || 271 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 272 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) 273 goto out; 274 debug("userauth-request for user %s service %s method %s", user, service, method); 275 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 276 277 if ((style = strchr(user, ':')) != NULL) 278 *style++ = 0; 279 280 if (authctxt->attempt >= 1024) 281 auth_maxtries_exceeded(ssh); 282 if (authctxt->attempt++ == 0) { 283 /* setup auth context */ 284 authctxt->pw = PRIVSEP(getpwnamallow(ssh, user)); 285 authctxt->user = xstrdup(user); 286 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 287 authctxt->valid = 1; 288 debug2_f("setting up authctxt for %s", user); 289 } else { 290 authctxt->valid = 0; 291 /* Invalid user, fake password information */ 292 authctxt->pw = fakepw(); 293 #ifdef SSH_AUDIT_EVENTS 294 PRIVSEP(audit_event(ssh, SSH_INVALID_USER)); 295 #endif 296 } 297 #ifdef USE_PAM 298 if (options.use_pam) 299 PRIVSEP(start_pam(ssh)); 300 #endif 301 ssh_packet_set_log_preamble(ssh, "%suser %s", 302 authctxt->valid ? "authenticating " : "invalid ", user); 303 setproctitle("%s%s", authctxt->valid ? user : "unknown", 304 use_privsep ? " [net]" : ""); 305 authctxt->service = xstrdup(service); 306 authctxt->style = style ? xstrdup(style) : NULL; 307 if (use_privsep) 308 mm_inform_authserv(service, style); 309 userauth_banner(ssh); 310 if (auth2_setup_methods_lists(authctxt) != 0) 311 ssh_packet_disconnect(ssh, 312 "no authentication methods enabled"); 313 } else if (strcmp(user, authctxt->user) != 0 || 314 strcmp(service, authctxt->service) != 0) { 315 ssh_packet_disconnect(ssh, "Change of username or service " 316 "not allowed: (%s,%s) -> (%s,%s)", 317 authctxt->user, authctxt->service, user, service); 318 } 319 /* reset state */ 320 auth2_challenge_stop(ssh); 321 322 #ifdef GSSAPI 323 /* XXX move to auth2_gssapi_stop() */ 324 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 325 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 326 #endif 327 328 auth2_authctxt_reset_info(authctxt); 329 authctxt->postponed = 0; 330 authctxt->server_caused_failure = 0; 331 332 /* try to authenticate user */ 333 m = authmethod_lookup(authctxt, method); 334 if (m != NULL && authctxt->failures < options.max_authtries) { 335 debug2("input_userauth_request: try method %s", method); 336 authenticated = m->userauth(ssh, method); 337 } 338 if (!authctxt->authenticated) 339 ensure_minimum_time_since(tstart, 340 user_specific_delay(authctxt->user)); 341 userauth_finish(ssh, authenticated, method, NULL); 342 r = 0; 343 out: 344 free(service); 345 free(user); 346 free(method); 347 return r; 348 } 349 350 void 351 userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method, 352 const char *submethod) 353 { 354 Authctxt *authctxt = ssh->authctxt; 355 Authmethod *m = NULL; 356 const char *method = packet_method; 357 char *methods; 358 int r, partial = 0; 359 360 if (authenticated) { 361 if (!authctxt->valid) { 362 fatal("INTERNAL ERROR: authenticated invalid user %s", 363 authctxt->user); 364 } 365 if (authctxt->postponed) 366 fatal("INTERNAL ERROR: authenticated and postponed"); 367 /* prefer primary authmethod name to possible synonym */ 368 if ((m = authmethod_byname(method)) == NULL) 369 fatal("INTERNAL ERROR: bad method %s", method); 370 method = m->name; 371 } 372 373 /* Special handling for root */ 374 if (authenticated && authctxt->pw->pw_uid == 0 && 375 !auth_root_allowed(ssh, method)) { 376 authenticated = 0; 377 #ifdef SSH_AUDIT_EVENTS 378 PRIVSEP(audit_event(ssh, SSH_LOGIN_ROOT_DENIED)); 379 #endif 380 } 381 382 if (authenticated && options.num_auth_methods != 0) { 383 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 384 authenticated = 0; 385 partial = 1; 386 } 387 } 388 389 /* Log before sending the reply */ 390 auth_log(ssh, authenticated, partial, method, submethod); 391 392 /* Update information exposed to session */ 393 if (authenticated || partial) 394 auth2_update_session_info(authctxt, method, submethod); 395 396 if (authctxt->postponed) 397 return; 398 399 #ifdef USE_PAM 400 if (options.use_pam && authenticated) { 401 int r, success = PRIVSEP(do_pam_account()); 402 403 /* If PAM returned a message, send it to the user. */ 404 if (sshbuf_len(loginmsg) > 0) { 405 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0) 406 fatal("%s: buffer error: %s", 407 __func__, ssh_err(r)); 408 userauth_send_banner(ssh, sshbuf_ptr(loginmsg)); 409 if ((r = ssh_packet_write_wait(ssh)) != 0) { 410 sshpkt_fatal(ssh, r, 411 "%s: send PAM banner", __func__); 412 } 413 } 414 if (!success) { 415 fatal("Access denied for user %s by PAM account " 416 "configuration", authctxt->user); 417 } 418 } 419 #endif 420 421 if (authenticated == 1) { 422 /* turn off userauth */ 423 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 424 &dispatch_protocol_ignore); 425 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 426 (r = sshpkt_send(ssh)) != 0 || 427 (r = ssh_packet_write_wait(ssh)) != 0) 428 fatal_fr(r, "send success packet"); 429 /* now we can break out */ 430 authctxt->success = 1; 431 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 432 } else { 433 /* Allow initial try of "none" auth without failure penalty */ 434 if (!partial && !authctxt->server_caused_failure && 435 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) { 436 authctxt->failures++; 437 BLACKLIST_NOTIFY(ssh, BLACKLIST_AUTH_FAIL, "ssh"); 438 } 439 if (authctxt->failures >= options.max_authtries) { 440 #ifdef SSH_AUDIT_EVENTS 441 PRIVSEP(audit_event(ssh, SSH_LOGIN_EXCEED_MAXTRIES)); 442 #endif 443 auth_maxtries_exceeded(ssh); 444 } 445 methods = authmethods_get(authctxt); 446 debug3_f("failure partial=%d next methods=\"%s\"", 447 partial, methods); 448 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 449 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 450 (r = sshpkt_put_u8(ssh, partial)) != 0 || 451 (r = sshpkt_send(ssh)) != 0 || 452 (r = ssh_packet_write_wait(ssh)) != 0) 453 fatal_fr(r, "send failure packet"); 454 free(methods); 455 } 456 } 457 458 /* 459 * Checks whether method is allowed by at least one AuthenticationMethods 460 * methods list. Returns 1 if allowed, or no methods lists configured. 461 * 0 otherwise. 462 */ 463 int 464 auth2_method_allowed(Authctxt *authctxt, const char *method, 465 const char *submethod) 466 { 467 u_int i; 468 469 /* 470 * NB. authctxt->num_auth_methods might be zero as a result of 471 * auth2_setup_methods_lists(), so check the configuration. 472 */ 473 if (options.num_auth_methods == 0) 474 return 1; 475 for (i = 0; i < authctxt->num_auth_methods; i++) { 476 if (list_starts_with(authctxt->auth_methods[i], method, 477 submethod) != MATCH_NONE) 478 return 1; 479 } 480 return 0; 481 } 482 483 static char * 484 authmethods_get(Authctxt *authctxt) 485 { 486 struct sshbuf *b; 487 char *list; 488 int i, r; 489 490 if ((b = sshbuf_new()) == NULL) 491 fatal_f("sshbuf_new failed"); 492 for (i = 0; authmethods[i] != NULL; i++) { 493 if (strcmp(authmethods[i]->name, "none") == 0) 494 continue; 495 if (authmethods[i]->enabled == NULL || 496 *(authmethods[i]->enabled) == 0) 497 continue; 498 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 499 NULL)) 500 continue; 501 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 502 authmethods[i]->name)) != 0) 503 fatal_fr(r, "buffer error"); 504 } 505 if ((list = sshbuf_dup_string(b)) == NULL) 506 fatal_f("sshbuf_dup_string failed"); 507 sshbuf_free(b); 508 return list; 509 } 510 511 static Authmethod * 512 authmethod_byname(const char *name) 513 { 514 int i; 515 516 if (name == NULL) 517 fatal_f("NULL authentication method name"); 518 for (i = 0; authmethods[i] != NULL; i++) { 519 if (strcmp(name, authmethods[i]->name) == 0 || 520 (authmethods[i]->synonym != NULL && 521 strcmp(name, authmethods[i]->synonym) == 0)) 522 return authmethods[i]; 523 } 524 debug_f("unrecognized authentication method name: %s", name); 525 return NULL; 526 } 527 528 static Authmethod * 529 authmethod_lookup(Authctxt *authctxt, const char *name) 530 { 531 Authmethod *method; 532 533 if ((method = authmethod_byname(name)) == NULL) 534 return NULL; 535 536 if (method->enabled == NULL || *(method->enabled) == 0) { 537 debug3_f("method %s not enabled", name); 538 return NULL; 539 } 540 if (!auth2_method_allowed(authctxt, method->name, NULL)) { 541 debug3_f("method %s not allowed " 542 "by AuthenticationMethods", name); 543 return NULL; 544 } 545 return method; 546 } 547 548 /* 549 * Check a comma-separated list of methods for validity. Is need_enable is 550 * non-zero, then also require that the methods are enabled. 551 * Returns 0 on success or -1 if the methods list is invalid. 552 */ 553 int 554 auth2_methods_valid(const char *_methods, int need_enable) 555 { 556 char *methods, *omethods, *method, *p; 557 u_int i, found; 558 int ret = -1; 559 560 if (*_methods == '\0') { 561 error("empty authentication method list"); 562 return -1; 563 } 564 omethods = methods = xstrdup(_methods); 565 while ((method = strsep(&methods, ",")) != NULL) { 566 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 567 if ((p = strchr(method, ':')) != NULL) 568 *p = '\0'; 569 if (strcmp(method, authmethods[i]->name) != 0) 570 continue; 571 if (need_enable) { 572 if (authmethods[i]->enabled == NULL || 573 *(authmethods[i]->enabled) == 0) { 574 error("Disabled method \"%s\" in " 575 "AuthenticationMethods list \"%s\"", 576 method, _methods); 577 goto out; 578 } 579 } 580 found = 1; 581 break; 582 } 583 if (!found) { 584 error("Unknown authentication method \"%s\" in list", 585 method); 586 goto out; 587 } 588 } 589 ret = 0; 590 out: 591 free(omethods); 592 return ret; 593 } 594 595 /* 596 * Prune the AuthenticationMethods supplied in the configuration, removing 597 * any methods lists that include disabled methods. Note that this might 598 * leave authctxt->num_auth_methods == 0, even when multiple required auth 599 * has been requested. For this reason, all tests for whether multiple is 600 * enabled should consult options.num_auth_methods directly. 601 */ 602 int 603 auth2_setup_methods_lists(Authctxt *authctxt) 604 { 605 u_int i; 606 607 /* First, normalise away the "any" pseudo-method */ 608 if (options.num_auth_methods == 1 && 609 strcmp(options.auth_methods[0], "any") == 0) { 610 free(options.auth_methods[0]); 611 options.auth_methods[0] = NULL; 612 options.num_auth_methods = 0; 613 } 614 615 if (options.num_auth_methods == 0) 616 return 0; 617 debug3_f("checking methods"); 618 authctxt->auth_methods = xcalloc(options.num_auth_methods, 619 sizeof(*authctxt->auth_methods)); 620 authctxt->num_auth_methods = 0; 621 for (i = 0; i < options.num_auth_methods; i++) { 622 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 623 logit("Authentication methods list \"%s\" contains " 624 "disabled method, skipping", 625 options.auth_methods[i]); 626 continue; 627 } 628 debug("authentication methods list %d: %s", 629 authctxt->num_auth_methods, options.auth_methods[i]); 630 authctxt->auth_methods[authctxt->num_auth_methods++] = 631 xstrdup(options.auth_methods[i]); 632 } 633 if (authctxt->num_auth_methods == 0) { 634 error("No AuthenticationMethods left after eliminating " 635 "disabled methods"); 636 return -1; 637 } 638 return 0; 639 } 640 641 static int 642 list_starts_with(const char *methods, const char *method, 643 const char *submethod) 644 { 645 size_t l = strlen(method); 646 int match; 647 const char *p; 648 649 if (strncmp(methods, method, l) != 0) 650 return MATCH_NONE; 651 p = methods + l; 652 match = MATCH_METHOD; 653 if (*p == ':') { 654 if (!submethod) 655 return MATCH_PARTIAL; 656 l = strlen(submethod); 657 p += 1; 658 if (strncmp(submethod, p, l)) 659 return MATCH_NONE; 660 p += l; 661 match = MATCH_BOTH; 662 } 663 if (*p != ',' && *p != '\0') 664 return MATCH_NONE; 665 return match; 666 } 667 668 /* 669 * Remove method from the start of a comma-separated list of methods. 670 * Returns 0 if the list of methods did not start with that method or 1 671 * if it did. 672 */ 673 static int 674 remove_method(char **methods, const char *method, const char *submethod) 675 { 676 char *omethods = *methods, *p; 677 size_t l = strlen(method); 678 int match; 679 680 match = list_starts_with(omethods, method, submethod); 681 if (match != MATCH_METHOD && match != MATCH_BOTH) 682 return 0; 683 p = omethods + l; 684 if (submethod && match == MATCH_BOTH) 685 p += 1 + strlen(submethod); /* include colon */ 686 if (*p == ',') 687 p++; 688 *methods = xstrdup(p); 689 free(omethods); 690 return 1; 691 } 692 693 /* 694 * Called after successful authentication. Will remove the successful method 695 * from the start of each list in which it occurs. If it was the last method 696 * in any list, then authentication is deemed successful. 697 * Returns 1 if the method completed any authentication list or 0 otherwise. 698 */ 699 int 700 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 701 const char *submethod) 702 { 703 u_int i, found = 0; 704 705 debug3_f("updating methods list after \"%s\"", method); 706 for (i = 0; i < authctxt->num_auth_methods; i++) { 707 if (!remove_method(&(authctxt->auth_methods[i]), method, 708 submethod)) 709 continue; 710 found = 1; 711 if (*authctxt->auth_methods[i] == '\0') { 712 debug2("authentication methods list %d complete", i); 713 return 1; 714 } 715 debug3("authentication methods list %d remaining: \"%s\"", 716 i, authctxt->auth_methods[i]); 717 } 718 /* This should not happen, but would be bad if it did */ 719 if (!found) 720 fatal_f("method not in AuthenticationMethods"); 721 return 0; 722 } 723 724 /* Reset method-specific information */ 725 void auth2_authctxt_reset_info(Authctxt *authctxt) 726 { 727 sshkey_free(authctxt->auth_method_key); 728 free(authctxt->auth_method_info); 729 authctxt->auth_method_key = NULL; 730 authctxt->auth_method_info = NULL; 731 } 732 733 /* Record auth method-specific information for logs */ 734 void 735 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 736 { 737 va_list ap; 738 int i; 739 740 free(authctxt->auth_method_info); 741 authctxt->auth_method_info = NULL; 742 743 va_start(ap, fmt); 744 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 745 va_end(ap); 746 747 if (i == -1) 748 fatal_f("vasprintf failed"); 749 } 750 751 /* 752 * Records a public key used in authentication. This is used for logging 753 * and to ensure that the same key is not subsequently accepted again for 754 * multiple authentication. 755 */ 756 void 757 auth2_record_key(Authctxt *authctxt, int authenticated, 758 const struct sshkey *key) 759 { 760 struct sshkey **tmp, *dup; 761 int r; 762 763 if ((r = sshkey_from_private(key, &dup)) != 0) 764 fatal_fr(r, "copy key"); 765 sshkey_free(authctxt->auth_method_key); 766 authctxt->auth_method_key = dup; 767 768 if (!authenticated) 769 return; 770 771 /* If authenticated, make sure we don't accept this key again */ 772 if ((r = sshkey_from_private(key, &dup)) != 0) 773 fatal_fr(r, "copy key"); 774 if (authctxt->nprev_keys >= INT_MAX || 775 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 776 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 777 fatal_f("reallocarray failed"); 778 authctxt->prev_keys = tmp; 779 authctxt->prev_keys[authctxt->nprev_keys] = dup; 780 authctxt->nprev_keys++; 781 782 } 783 784 /* Checks whether a key has already been previously used for authentication */ 785 int 786 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 787 { 788 u_int i; 789 char *fp; 790 791 for (i = 0; i < authctxt->nprev_keys; i++) { 792 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 793 fp = sshkey_fingerprint(authctxt->prev_keys[i], 794 options.fingerprint_hash, SSH_FP_DEFAULT); 795 debug3_f("key already used: %s %s", 796 sshkey_type(authctxt->prev_keys[i]), 797 fp == NULL ? "UNKNOWN" : fp); 798 free(fp); 799 return 1; 800 } 801 } 802 return 0; 803 } 804 805 /* 806 * Updates authctxt->session_info with details of authentication. Should be 807 * whenever an authentication method succeeds. 808 */ 809 void 810 auth2_update_session_info(Authctxt *authctxt, const char *method, 811 const char *submethod) 812 { 813 int r; 814 815 if (authctxt->session_info == NULL) { 816 if ((authctxt->session_info = sshbuf_new()) == NULL) 817 fatal_f("sshbuf_new"); 818 } 819 820 /* Append method[/submethod] */ 821 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 822 method, submethod == NULL ? "" : "/", 823 submethod == NULL ? "" : submethod)) != 0) 824 fatal_fr(r, "append method"); 825 826 /* Append key if present */ 827 if (authctxt->auth_method_key != NULL) { 828 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 829 (r = sshkey_format_text(authctxt->auth_method_key, 830 authctxt->session_info)) != 0) 831 fatal_fr(r, "append key"); 832 } 833 834 if (authctxt->auth_method_info != NULL) { 835 /* Ensure no ambiguity here */ 836 if (strchr(authctxt->auth_method_info, '\n') != NULL) 837 fatal_f("auth_method_info contains \\n"); 838 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 839 (r = sshbuf_putf(authctxt->session_info, "%s", 840 authctxt->auth_method_info)) != 0) { 841 fatal_fr(r, "append method info"); 842 } 843 } 844 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 845 fatal_fr(r, "append"); 846 } 847 848