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 __RCSID("$FreeBSD$"); 28 29 #include <sys/types.h> 30 #include <sys/stat.h> 31 #include <sys/uio.h> 32 33 #include <fcntl.h> 34 #include <limits.h> 35 #include <pwd.h> 36 #include <stdarg.h> 37 #include <string.h> 38 #include <unistd.h> 39 #include <time.h> 40 41 #include "stdlib.h" 42 #include "atomicio.h" 43 #include "xmalloc.h" 44 #include "ssh2.h" 45 #include "packet.h" 46 #include "log.h" 47 #include "sshbuf.h" 48 #include "misc.h" 49 #include "servconf.h" 50 #include "compat.h" 51 #include "sshkey.h" 52 #include "hostfile.h" 53 #include "auth.h" 54 #include "dispatch.h" 55 #include "pathnames.h" 56 #include "ssherr.h" 57 #include "blacklist_client.h" 58 #ifdef GSSAPI 59 #include "ssh-gss.h" 60 #endif 61 #include "monitor_wrap.h" 62 #include "digest.h" 63 64 /* import */ 65 extern ServerOptions options; 66 extern struct sshbuf *loginmsg; 67 68 /* methods */ 69 70 extern Authmethod method_none; 71 extern Authmethod method_pubkey; 72 extern Authmethod method_passwd; 73 extern Authmethod method_kbdint; 74 extern Authmethod method_hostbased; 75 #ifdef GSSAPI 76 extern Authmethod method_gssapi; 77 #endif 78 79 Authmethod *authmethods[] = { 80 &method_none, 81 &method_pubkey, 82 #ifdef GSSAPI 83 &method_gssapi, 84 #endif 85 &method_passwd, 86 &method_kbdint, 87 &method_hostbased, 88 NULL 89 }; 90 91 /* protocol */ 92 93 static int input_service_request(int, u_int32_t, struct ssh *); 94 static int input_userauth_request(int, u_int32_t, struct ssh *); 95 96 /* helper */ 97 static Authmethod *authmethod_byname(const char *); 98 static Authmethod *authmethod_lookup(Authctxt *, const char *); 99 static char *authmethods_get(Authctxt *authctxt); 100 101 #define MATCH_NONE 0 /* method or submethod mismatch */ 102 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 103 #define MATCH_BOTH 2 /* method and submethod match */ 104 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 105 static int list_starts_with(const char *, const char *, const char *); 106 107 char * 108 auth2_read_banner(void) 109 { 110 struct stat st; 111 char *banner = NULL; 112 size_t len, n; 113 int fd; 114 115 if ((fd = open(options.banner, O_RDONLY)) == -1) 116 return (NULL); 117 if (fstat(fd, &st) == -1) { 118 close(fd); 119 return (NULL); 120 } 121 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 122 close(fd); 123 return (NULL); 124 } 125 126 len = (size_t)st.st_size; /* truncate */ 127 banner = xmalloc(len + 1); 128 n = atomicio(read, fd, banner, len); 129 close(fd); 130 131 if (n != len) { 132 free(banner); 133 return (NULL); 134 } 135 banner[n] = '\0'; 136 137 return (banner); 138 } 139 140 static void 141 userauth_send_banner(struct ssh *ssh, const char *msg) 142 { 143 int r; 144 145 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 || 146 (r = sshpkt_put_cstring(ssh, msg)) != 0 || 147 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */ 148 (r = sshpkt_send(ssh)) != 0) 149 fatal_fr(r, "send packet"); 150 debug("%s: sent", __func__); 151 } 152 153 static void 154 userauth_banner(struct ssh *ssh) 155 { 156 char *banner = NULL; 157 158 if (options.banner == NULL) 159 return; 160 161 if ((banner = PRIVSEP(auth2_read_banner())) == NULL) 162 goto done; 163 userauth_send_banner(ssh, banner); 164 165 done: 166 free(banner); 167 } 168 169 /* 170 * loop until authctxt->success == TRUE 171 */ 172 void 173 do_authentication2(struct ssh *ssh) 174 { 175 Authctxt *authctxt = ssh->authctxt; 176 177 ssh_dispatch_init(ssh, &dispatch_protocol_error); 178 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); 179 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); 180 ssh->authctxt = NULL; 181 } 182 183 /*ARGSUSED*/ 184 static int 185 input_service_request(int type, u_int32_t seq, struct ssh *ssh) 186 { 187 Authctxt *authctxt = ssh->authctxt; 188 char *service = NULL; 189 int r, acceptit = 0; 190 191 if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 192 (r = sshpkt_get_end(ssh)) != 0) 193 goto out; 194 195 if (authctxt == NULL) 196 fatal("input_service_request: no authctxt"); 197 198 if (strcmp(service, "ssh-userauth") == 0) { 199 if (!authctxt->success) { 200 acceptit = 1; 201 /* now we can handle user-auth requests */ 202 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 203 &input_userauth_request); 204 } 205 } 206 /* XXX all other service requests are denied */ 207 208 if (acceptit) { 209 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 || 210 (r = sshpkt_put_cstring(ssh, service)) != 0 || 211 (r = sshpkt_send(ssh)) != 0 || 212 (r = ssh_packet_write_wait(ssh)) != 0) 213 goto out; 214 } else { 215 debug("bad service request %s", service); 216 ssh_packet_disconnect(ssh, "bad service request %s", service); 217 } 218 r = 0; 219 out: 220 free(service); 221 return r; 222 } 223 224 #define MIN_FAIL_DELAY_SECONDS 0.005 225 static double 226 user_specific_delay(const char *user) 227 { 228 char b[512]; 229 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 230 u_char *hash = xmalloc(len); 231 double delay; 232 233 (void)snprintf(b, sizeof b, "%llu%s", 234 (unsigned long long)options.timing_secret, user); 235 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 236 fatal_f("ssh_digest_memory"); 237 /* 0-4.2 ms of delay */ 238 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 239 freezero(hash, len); 240 debug3_f("user specific delay %0.3lfms", delay/1000); 241 return MIN_FAIL_DELAY_SECONDS + delay; 242 } 243 244 static void 245 ensure_minimum_time_since(double start, double seconds) 246 { 247 struct timespec ts; 248 double elapsed = monotime_double() - start, req = seconds, remain; 249 250 /* if we've already passed the requested time, scale up */ 251 while ((remain = seconds - elapsed) < 0.0) 252 seconds *= 2; 253 254 ts.tv_sec = remain; 255 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; 256 debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 257 elapsed*1000, remain*1000, req*1000); 258 nanosleep(&ts, NULL); 259 } 260 261 /*ARGSUSED*/ 262 static int 263 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 264 { 265 Authctxt *authctxt = ssh->authctxt; 266 Authmethod *m = NULL; 267 char *user = NULL, *service = NULL, *method = NULL, *style = NULL; 268 int r, authenticated = 0; 269 double tstart = monotime_double(); 270 271 if (authctxt == NULL) 272 fatal("input_userauth_request: no authctxt"); 273 274 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || 275 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 276 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) 277 goto out; 278 debug("userauth-request for user %s service %s method %s", user, service, method); 279 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 280 281 if ((style = strchr(user, ':')) != NULL) 282 *style++ = 0; 283 284 if (authctxt->attempt >= 1024) 285 auth_maxtries_exceeded(ssh); 286 if (authctxt->attempt++ == 0) { 287 /* setup auth context */ 288 authctxt->pw = PRIVSEP(getpwnamallow(ssh, user)); 289 authctxt->user = xstrdup(user); 290 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 291 authctxt->valid = 1; 292 debug2_f("setting up authctxt for %s", user); 293 } else { 294 authctxt->valid = 0; 295 /* Invalid user, fake password information */ 296 authctxt->pw = fakepw(); 297 #ifdef SSH_AUDIT_EVENTS 298 PRIVSEP(audit_event(ssh, SSH_INVALID_USER)); 299 #endif 300 } 301 #ifdef USE_PAM 302 if (options.use_pam) 303 PRIVSEP(start_pam(ssh)); 304 #endif 305 ssh_packet_set_log_preamble(ssh, "%suser %s", 306 authctxt->valid ? "authenticating " : "invalid ", user); 307 setproctitle("%s%s", authctxt->valid ? user : "unknown", 308 use_privsep ? " [net]" : ""); 309 authctxt->service = xstrdup(service); 310 authctxt->style = style ? xstrdup(style) : NULL; 311 if (use_privsep) 312 mm_inform_authserv(service, style); 313 userauth_banner(ssh); 314 if (auth2_setup_methods_lists(authctxt) != 0) 315 ssh_packet_disconnect(ssh, 316 "no authentication methods enabled"); 317 } else if (strcmp(user, authctxt->user) != 0 || 318 strcmp(service, authctxt->service) != 0) { 319 ssh_packet_disconnect(ssh, "Change of username or service " 320 "not allowed: (%s,%s) -> (%s,%s)", 321 authctxt->user, authctxt->service, user, service); 322 } 323 /* reset state */ 324 auth2_challenge_stop(ssh); 325 326 #ifdef GSSAPI 327 /* XXX move to auth2_gssapi_stop() */ 328 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 329 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 330 #endif 331 332 auth2_authctxt_reset_info(authctxt); 333 authctxt->postponed = 0; 334 authctxt->server_caused_failure = 0; 335 336 /* try to authenticate user */ 337 m = authmethod_lookup(authctxt, method); 338 if (m != NULL && authctxt->failures < options.max_authtries) { 339 debug2("input_userauth_request: try method %s", method); 340 authenticated = m->userauth(ssh, method); 341 } 342 if (!authctxt->authenticated) 343 ensure_minimum_time_since(tstart, 344 user_specific_delay(authctxt->user)); 345 userauth_finish(ssh, authenticated, method, NULL); 346 r = 0; 347 out: 348 free(service); 349 free(user); 350 free(method); 351 return r; 352 } 353 354 void 355 userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method, 356 const char *submethod) 357 { 358 Authctxt *authctxt = ssh->authctxt; 359 Authmethod *m = NULL; 360 const char *method = packet_method; 361 char *methods; 362 int r, partial = 0; 363 364 if (authenticated) { 365 if (!authctxt->valid) { 366 fatal("INTERNAL ERROR: authenticated invalid user %s", 367 authctxt->user); 368 } 369 if (authctxt->postponed) 370 fatal("INTERNAL ERROR: authenticated and postponed"); 371 /* prefer primary authmethod name to possible synonym */ 372 if ((m = authmethod_byname(method)) == NULL) 373 fatal("INTERNAL ERROR: bad method %s", method); 374 method = m->name; 375 } 376 377 /* Special handling for root */ 378 if (authenticated && authctxt->pw->pw_uid == 0 && 379 !auth_root_allowed(ssh, method)) { 380 authenticated = 0; 381 #ifdef SSH_AUDIT_EVENTS 382 PRIVSEP(audit_event(ssh, SSH_LOGIN_ROOT_DENIED)); 383 #endif 384 } 385 386 if (authenticated && options.num_auth_methods != 0) { 387 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 388 authenticated = 0; 389 partial = 1; 390 } 391 } 392 393 /* Log before sending the reply */ 394 auth_log(ssh, authenticated, partial, method, submethod); 395 396 /* Update information exposed to session */ 397 if (authenticated || partial) 398 auth2_update_session_info(authctxt, method, submethod); 399 400 if (authctxt->postponed) 401 return; 402 403 #ifdef USE_PAM 404 if (options.use_pam && authenticated) { 405 int r, success = PRIVSEP(do_pam_account()); 406 407 /* If PAM returned a message, send it to the user. */ 408 if (sshbuf_len(loginmsg) > 0) { 409 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0) 410 fatal("%s: buffer error: %s", 411 __func__, ssh_err(r)); 412 userauth_send_banner(ssh, sshbuf_ptr(loginmsg)); 413 if ((r = ssh_packet_write_wait(ssh)) != 0) { 414 sshpkt_fatal(ssh, r, 415 "%s: send PAM banner", __func__); 416 } 417 } 418 if (!success) { 419 fatal("Access denied for user %s by PAM account " 420 "configuration", authctxt->user); 421 } 422 } 423 #endif 424 425 if (authenticated == 1) { 426 /* turn off userauth */ 427 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 428 &dispatch_protocol_ignore); 429 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 430 (r = sshpkt_send(ssh)) != 0 || 431 (r = ssh_packet_write_wait(ssh)) != 0) 432 fatal_fr(r, "send success packet"); 433 /* now we can break out */ 434 authctxt->success = 1; 435 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 436 } else { 437 /* Allow initial try of "none" auth without failure penalty */ 438 if (!partial && !authctxt->server_caused_failure && 439 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) { 440 authctxt->failures++; 441 BLACKLIST_NOTIFY(ssh, BLACKLIST_AUTH_FAIL, "ssh"); 442 } 443 if (authctxt->failures >= options.max_authtries) { 444 #ifdef SSH_AUDIT_EVENTS 445 PRIVSEP(audit_event(ssh, SSH_LOGIN_EXCEED_MAXTRIES)); 446 #endif 447 auth_maxtries_exceeded(ssh); 448 } 449 methods = authmethods_get(authctxt); 450 debug3_f("failure partial=%d next methods=\"%s\"", 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_fr(r, "send failure packet"); 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_f("sshbuf_new failed"); 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_fr(r, "buffer error"); 508 } 509 if ((list = sshbuf_dup_string(b)) == NULL) 510 fatal_f("sshbuf_dup_string failed"); 511 sshbuf_free(b); 512 return list; 513 } 514 515 static Authmethod * 516 authmethod_byname(const char *name) 517 { 518 int i; 519 520 if (name == NULL) 521 fatal_f("NULL authentication method name"); 522 for (i = 0; authmethods[i] != NULL; i++) { 523 if (strcmp(name, authmethods[i]->name) == 0 || 524 (authmethods[i]->synonym != NULL && 525 strcmp(name, authmethods[i]->synonym) == 0)) 526 return authmethods[i]; 527 } 528 debug_f("unrecognized authentication method name: %s", name); 529 return NULL; 530 } 531 532 static Authmethod * 533 authmethod_lookup(Authctxt *authctxt, const char *name) 534 { 535 Authmethod *method; 536 537 if ((method = authmethod_byname(name)) == NULL) 538 return NULL; 539 540 if (method->enabled == NULL || *(method->enabled) == 0) { 541 debug3_f("method %s not enabled", name); 542 return NULL; 543 } 544 if (!auth2_method_allowed(authctxt, method->name, NULL)) { 545 debug3_f("method %s not allowed " 546 "by AuthenticationMethods", name); 547 return NULL; 548 } 549 return method; 550 } 551 552 /* 553 * Check a comma-separated list of methods for validity. Is need_enable is 554 * non-zero, then also require that the methods are enabled. 555 * Returns 0 on success or -1 if the methods list is invalid. 556 */ 557 int 558 auth2_methods_valid(const char *_methods, int need_enable) 559 { 560 char *methods, *omethods, *method, *p; 561 u_int i, found; 562 int ret = -1; 563 564 if (*_methods == '\0') { 565 error("empty authentication method list"); 566 return -1; 567 } 568 omethods = methods = xstrdup(_methods); 569 while ((method = strsep(&methods, ",")) != NULL) { 570 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 571 if ((p = strchr(method, ':')) != NULL) 572 *p = '\0'; 573 if (strcmp(method, authmethods[i]->name) != 0) 574 continue; 575 if (need_enable) { 576 if (authmethods[i]->enabled == NULL || 577 *(authmethods[i]->enabled) == 0) { 578 error("Disabled method \"%s\" in " 579 "AuthenticationMethods list \"%s\"", 580 method, _methods); 581 goto out; 582 } 583 } 584 found = 1; 585 break; 586 } 587 if (!found) { 588 error("Unknown authentication method \"%s\" in list", 589 method); 590 goto out; 591 } 592 } 593 ret = 0; 594 out: 595 free(omethods); 596 return ret; 597 } 598 599 /* 600 * Prune the AuthenticationMethods supplied in the configuration, removing 601 * any methods lists that include disabled methods. Note that this might 602 * leave authctxt->num_auth_methods == 0, even when multiple required auth 603 * has been requested. For this reason, all tests for whether multiple is 604 * enabled should consult options.num_auth_methods directly. 605 */ 606 int 607 auth2_setup_methods_lists(Authctxt *authctxt) 608 { 609 u_int i; 610 611 /* First, normalise away the "any" pseudo-method */ 612 if (options.num_auth_methods == 1 && 613 strcmp(options.auth_methods[0], "any") == 0) { 614 free(options.auth_methods[0]); 615 options.auth_methods[0] = NULL; 616 options.num_auth_methods = 0; 617 } 618 619 if (options.num_auth_methods == 0) 620 return 0; 621 debug3_f("checking methods"); 622 authctxt->auth_methods = xcalloc(options.num_auth_methods, 623 sizeof(*authctxt->auth_methods)); 624 authctxt->num_auth_methods = 0; 625 for (i = 0; i < options.num_auth_methods; i++) { 626 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 627 logit("Authentication methods list \"%s\" contains " 628 "disabled method, skipping", 629 options.auth_methods[i]); 630 continue; 631 } 632 debug("authentication methods list %d: %s", 633 authctxt->num_auth_methods, options.auth_methods[i]); 634 authctxt->auth_methods[authctxt->num_auth_methods++] = 635 xstrdup(options.auth_methods[i]); 636 } 637 if (authctxt->num_auth_methods == 0) { 638 error("No AuthenticationMethods left after eliminating " 639 "disabled methods"); 640 return -1; 641 } 642 return 0; 643 } 644 645 static int 646 list_starts_with(const char *methods, const char *method, 647 const char *submethod) 648 { 649 size_t l = strlen(method); 650 int match; 651 const char *p; 652 653 if (strncmp(methods, method, l) != 0) 654 return MATCH_NONE; 655 p = methods + l; 656 match = MATCH_METHOD; 657 if (*p == ':') { 658 if (!submethod) 659 return MATCH_PARTIAL; 660 l = strlen(submethod); 661 p += 1; 662 if (strncmp(submethod, p, l)) 663 return MATCH_NONE; 664 p += l; 665 match = MATCH_BOTH; 666 } 667 if (*p != ',' && *p != '\0') 668 return MATCH_NONE; 669 return match; 670 } 671 672 /* 673 * Remove method from the start of a comma-separated list of methods. 674 * Returns 0 if the list of methods did not start with that method or 1 675 * if it did. 676 */ 677 static int 678 remove_method(char **methods, const char *method, const char *submethod) 679 { 680 char *omethods = *methods, *p; 681 size_t l = strlen(method); 682 int match; 683 684 match = list_starts_with(omethods, method, submethod); 685 if (match != MATCH_METHOD && match != MATCH_BOTH) 686 return 0; 687 p = omethods + l; 688 if (submethod && match == MATCH_BOTH) 689 p += 1 + strlen(submethod); /* include colon */ 690 if (*p == ',') 691 p++; 692 *methods = xstrdup(p); 693 free(omethods); 694 return 1; 695 } 696 697 /* 698 * Called after successful authentication. Will remove the successful method 699 * from the start of each list in which it occurs. If it was the last method 700 * in any list, then authentication is deemed successful. 701 * Returns 1 if the method completed any authentication list or 0 otherwise. 702 */ 703 int 704 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 705 const char *submethod) 706 { 707 u_int i, found = 0; 708 709 debug3_f("updating methods list after \"%s\"", method); 710 for (i = 0; i < authctxt->num_auth_methods; i++) { 711 if (!remove_method(&(authctxt->auth_methods[i]), method, 712 submethod)) 713 continue; 714 found = 1; 715 if (*authctxt->auth_methods[i] == '\0') { 716 debug2("authentication methods list %d complete", i); 717 return 1; 718 } 719 debug3("authentication methods list %d remaining: \"%s\"", 720 i, authctxt->auth_methods[i]); 721 } 722 /* This should not happen, but would be bad if it did */ 723 if (!found) 724 fatal_f("method not in AuthenticationMethods"); 725 return 0; 726 } 727 728 /* Reset method-specific information */ 729 void auth2_authctxt_reset_info(Authctxt *authctxt) 730 { 731 sshkey_free(authctxt->auth_method_key); 732 free(authctxt->auth_method_info); 733 authctxt->auth_method_key = NULL; 734 authctxt->auth_method_info = NULL; 735 } 736 737 /* Record auth method-specific information for logs */ 738 void 739 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 740 { 741 va_list ap; 742 int i; 743 744 free(authctxt->auth_method_info); 745 authctxt->auth_method_info = NULL; 746 747 va_start(ap, fmt); 748 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 749 va_end(ap); 750 751 if (i == -1) 752 fatal_f("vasprintf failed"); 753 } 754 755 /* 756 * Records a public key used in authentication. This is used for logging 757 * and to ensure that the same key is not subsequently accepted again for 758 * multiple authentication. 759 */ 760 void 761 auth2_record_key(Authctxt *authctxt, int authenticated, 762 const struct sshkey *key) 763 { 764 struct sshkey **tmp, *dup; 765 int r; 766 767 if ((r = sshkey_from_private(key, &dup)) != 0) 768 fatal_fr(r, "copy key"); 769 sshkey_free(authctxt->auth_method_key); 770 authctxt->auth_method_key = dup; 771 772 if (!authenticated) 773 return; 774 775 /* If authenticated, make sure we don't accept this key again */ 776 if ((r = sshkey_from_private(key, &dup)) != 0) 777 fatal_fr(r, "copy key"); 778 if (authctxt->nprev_keys >= INT_MAX || 779 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 780 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 781 fatal_f("reallocarray failed"); 782 authctxt->prev_keys = tmp; 783 authctxt->prev_keys[authctxt->nprev_keys] = dup; 784 authctxt->nprev_keys++; 785 786 } 787 788 /* Checks whether a key has already been previously used for authentication */ 789 int 790 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 791 { 792 u_int i; 793 char *fp; 794 795 for (i = 0; i < authctxt->nprev_keys; i++) { 796 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 797 fp = sshkey_fingerprint(authctxt->prev_keys[i], 798 options.fingerprint_hash, SSH_FP_DEFAULT); 799 debug3_f("key already used: %s %s", 800 sshkey_type(authctxt->prev_keys[i]), 801 fp == NULL ? "UNKNOWN" : fp); 802 free(fp); 803 return 1; 804 } 805 } 806 return 0; 807 } 808 809 /* 810 * Updates authctxt->session_info with details of authentication. Should be 811 * whenever an authentication method succeeds. 812 */ 813 void 814 auth2_update_session_info(Authctxt *authctxt, const char *method, 815 const char *submethod) 816 { 817 int r; 818 819 if (authctxt->session_info == NULL) { 820 if ((authctxt->session_info = sshbuf_new()) == NULL) 821 fatal_f("sshbuf_new"); 822 } 823 824 /* Append method[/submethod] */ 825 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 826 method, submethod == NULL ? "" : "/", 827 submethod == NULL ? "" : submethod)) != 0) 828 fatal_fr(r, "append method"); 829 830 /* Append key if present */ 831 if (authctxt->auth_method_key != NULL) { 832 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 833 (r = sshkey_format_text(authctxt->auth_method_key, 834 authctxt->session_info)) != 0) 835 fatal_fr(r, "append key"); 836 } 837 838 if (authctxt->auth_method_info != NULL) { 839 /* Ensure no ambiguity here */ 840 if (strchr(authctxt->auth_method_info, '\n') != NULL) 841 fatal_f("auth_method_info contains \\n"); 842 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 843 (r = sshbuf_putf(authctxt->session_info, "%s", 844 authctxt->auth_method_info)) != 0) { 845 fatal_fr(r, "append method info"); 846 } 847 } 848 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 849 fatal_fr(r, "append"); 850 } 851 852