1 /* $OpenBSD: auth2.c,v 1.160 2021/01/27 10:05:28 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 #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_lookup(Authctxt *, const char *); 96 static char *authmethods_get(Authctxt *authctxt); 97 98 #define MATCH_NONE 0 /* method or submethod mismatch */ 99 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 100 #define MATCH_BOTH 2 /* method and submethod match */ 101 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 102 static int list_starts_with(const char *, const char *, const char *); 103 104 char * 105 auth2_read_banner(void) 106 { 107 struct stat st; 108 char *banner = NULL; 109 size_t len, n; 110 int fd; 111 112 if ((fd = open(options.banner, O_RDONLY)) == -1) 113 return (NULL); 114 if (fstat(fd, &st) == -1) { 115 close(fd); 116 return (NULL); 117 } 118 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 119 close(fd); 120 return (NULL); 121 } 122 123 len = (size_t)st.st_size; /* truncate */ 124 banner = xmalloc(len + 1); 125 n = atomicio(read, fd, banner, len); 126 close(fd); 127 128 if (n != len) { 129 free(banner); 130 return (NULL); 131 } 132 banner[n] = '\0'; 133 134 return (banner); 135 } 136 137 static void 138 userauth_send_banner(struct ssh *ssh, const char *msg) 139 { 140 int r; 141 142 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 || 143 (r = sshpkt_put_cstring(ssh, msg)) != 0 || 144 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */ 145 (r = sshpkt_send(ssh)) != 0) 146 fatal_fr(r, "send packet"); 147 debug("%s: sent", __func__); 148 } 149 150 static void 151 userauth_banner(struct ssh *ssh) 152 { 153 char *banner = NULL; 154 155 if (options.banner == NULL) 156 return; 157 158 if ((banner = PRIVSEP(auth2_read_banner())) == NULL) 159 goto done; 160 userauth_send_banner(ssh, banner); 161 162 done: 163 free(banner); 164 } 165 166 /* 167 * loop until authctxt->success == TRUE 168 */ 169 void 170 do_authentication2(struct ssh *ssh) 171 { 172 Authctxt *authctxt = ssh->authctxt; 173 174 ssh_dispatch_init(ssh, &dispatch_protocol_error); 175 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); 176 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); 177 ssh->authctxt = NULL; 178 } 179 180 /*ARGSUSED*/ 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 /*ARGSUSED*/ 259 static int 260 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 261 { 262 Authctxt *authctxt = ssh->authctxt; 263 Authmethod *m = NULL; 264 char *user = NULL, *service = NULL, *method = NULL, *style = NULL; 265 int r, authenticated = 0; 266 double tstart = monotime_double(); 267 268 if (authctxt == NULL) 269 fatal("input_userauth_request: no authctxt"); 270 271 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || 272 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 273 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) 274 goto out; 275 debug("userauth-request for user %s service %s method %s", user, service, method); 276 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 277 278 if ((style = strchr(user, ':')) != NULL) 279 *style++ = 0; 280 281 if (authctxt->attempt++ == 0) { 282 /* setup auth context */ 283 authctxt->pw = PRIVSEP(getpwnamallow(ssh, user)); 284 authctxt->user = xstrdup(user); 285 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 286 authctxt->valid = 1; 287 debug2_f("setting up authctxt for %s", user); 288 } else { 289 /* Invalid user, fake password information */ 290 authctxt->pw = fakepw(); 291 #ifdef SSH_AUDIT_EVENTS 292 PRIVSEP(audit_event(ssh, SSH_INVALID_USER)); 293 #endif 294 } 295 #ifdef USE_PAM 296 if (options.use_pam) 297 PRIVSEP(start_pam(ssh)); 298 #endif 299 ssh_packet_set_log_preamble(ssh, "%suser %s", 300 authctxt->valid ? "authenticating " : "invalid ", user); 301 setproctitle("%s%s", authctxt->valid ? user : "unknown", 302 use_privsep ? " [net]" : ""); 303 authctxt->service = xstrdup(service); 304 authctxt->style = style ? xstrdup(style) : NULL; 305 if (use_privsep) 306 mm_inform_authserv(service, style); 307 userauth_banner(ssh); 308 if (auth2_setup_methods_lists(authctxt) != 0) 309 ssh_packet_disconnect(ssh, 310 "no authentication methods enabled"); 311 } else if (strcmp(user, authctxt->user) != 0 || 312 strcmp(service, authctxt->service) != 0) { 313 ssh_packet_disconnect(ssh, "Change of username or service " 314 "not allowed: (%s,%s) -> (%s,%s)", 315 authctxt->user, authctxt->service, user, service); 316 } 317 /* reset state */ 318 auth2_challenge_stop(ssh); 319 320 #ifdef GSSAPI 321 /* XXX move to auth2_gssapi_stop() */ 322 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 323 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 324 #endif 325 326 auth2_authctxt_reset_info(authctxt); 327 authctxt->postponed = 0; 328 authctxt->server_caused_failure = 0; 329 330 /* try to authenticate user */ 331 m = authmethod_lookup(authctxt, method); 332 if (m != NULL && authctxt->failures < options.max_authtries) { 333 debug2("input_userauth_request: try method %s", method); 334 authenticated = m->userauth(ssh); 335 } 336 if (!authctxt->authenticated) 337 ensure_minimum_time_since(tstart, 338 user_specific_delay(authctxt->user)); 339 userauth_finish(ssh, authenticated, method, NULL); 340 r = 0; 341 out: 342 free(service); 343 free(user); 344 free(method); 345 return r; 346 } 347 348 void 349 userauth_finish(struct ssh *ssh, int authenticated, const char *method, 350 const char *submethod) 351 { 352 Authctxt *authctxt = ssh->authctxt; 353 char *methods; 354 int r, partial = 0; 355 356 if (!authctxt->valid && authenticated) 357 fatal("INTERNAL ERROR: authenticated invalid user %s", 358 authctxt->user); 359 if (authenticated && authctxt->postponed) 360 fatal("INTERNAL ERROR: authenticated and postponed"); 361 362 /* Special handling for root */ 363 if (authenticated && authctxt->pw->pw_uid == 0 && 364 !auth_root_allowed(ssh, method)) { 365 authenticated = 0; 366 #ifdef SSH_AUDIT_EVENTS 367 PRIVSEP(audit_event(ssh, SSH_LOGIN_ROOT_DENIED)); 368 #endif 369 } 370 371 if (authenticated && options.num_auth_methods != 0) { 372 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 373 authenticated = 0; 374 partial = 1; 375 } 376 } 377 378 /* Log before sending the reply */ 379 auth_log(ssh, authenticated, partial, method, submethod); 380 381 /* Update information exposed to session */ 382 if (authenticated || partial) 383 auth2_update_session_info(authctxt, method, submethod); 384 385 if (authctxt->postponed) 386 return; 387 388 #ifdef USE_PAM 389 if (options.use_pam && authenticated) { 390 int r, success = PRIVSEP(do_pam_account()); 391 392 /* If PAM returned a message, send it to the user. */ 393 if (sshbuf_len(loginmsg) > 0) { 394 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0) 395 fatal("%s: buffer error: %s", 396 __func__, ssh_err(r)); 397 userauth_send_banner(ssh, sshbuf_ptr(loginmsg)); 398 if ((r = ssh_packet_write_wait(ssh)) != 0) { 399 sshpkt_fatal(ssh, r, 400 "%s: send PAM banner", __func__); 401 } 402 } 403 if (!success) { 404 fatal("Access denied for user %s by PAM account " 405 "configuration", authctxt->user); 406 } 407 } 408 #endif 409 410 if (authenticated == 1) { 411 /* turn off userauth */ 412 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 413 &dispatch_protocol_ignore); 414 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 415 (r = sshpkt_send(ssh)) != 0 || 416 (r = ssh_packet_write_wait(ssh)) != 0) 417 fatal_fr(r, "send success packet"); 418 /* now we can break out */ 419 authctxt->success = 1; 420 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 421 } else { 422 /* Allow initial try of "none" auth without failure penalty */ 423 if (!partial && !authctxt->server_caused_failure && 424 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) 425 authctxt->failures++; 426 if (authctxt->failures >= options.max_authtries) { 427 #ifdef SSH_AUDIT_EVENTS 428 PRIVSEP(audit_event(ssh, SSH_LOGIN_EXCEED_MAXTRIES)); 429 #endif 430 auth_maxtries_exceeded(ssh); 431 } 432 methods = authmethods_get(authctxt); 433 debug3_f("failure partial=%d next methods=\"%s\"", 434 partial, methods); 435 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 436 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 437 (r = sshpkt_put_u8(ssh, partial)) != 0 || 438 (r = sshpkt_send(ssh)) != 0 || 439 (r = ssh_packet_write_wait(ssh)) != 0) 440 fatal_fr(r, "send failure packet"); 441 free(methods); 442 } 443 } 444 445 /* 446 * Checks whether method is allowed by at least one AuthenticationMethods 447 * methods list. Returns 1 if allowed, or no methods lists configured. 448 * 0 otherwise. 449 */ 450 int 451 auth2_method_allowed(Authctxt *authctxt, const char *method, 452 const char *submethod) 453 { 454 u_int i; 455 456 /* 457 * NB. authctxt->num_auth_methods might be zero as a result of 458 * auth2_setup_methods_lists(), so check the configuration. 459 */ 460 if (options.num_auth_methods == 0) 461 return 1; 462 for (i = 0; i < authctxt->num_auth_methods; i++) { 463 if (list_starts_with(authctxt->auth_methods[i], method, 464 submethod) != MATCH_NONE) 465 return 1; 466 } 467 return 0; 468 } 469 470 static char * 471 authmethods_get(Authctxt *authctxt) 472 { 473 struct sshbuf *b; 474 char *list; 475 int i, r; 476 477 if ((b = sshbuf_new()) == NULL) 478 fatal_f("sshbuf_new failed"); 479 for (i = 0; authmethods[i] != NULL; i++) { 480 if (strcmp(authmethods[i]->name, "none") == 0) 481 continue; 482 if (authmethods[i]->enabled == NULL || 483 *(authmethods[i]->enabled) == 0) 484 continue; 485 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 486 NULL)) 487 continue; 488 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 489 authmethods[i]->name)) != 0) 490 fatal_fr(r, "buffer error"); 491 } 492 if ((list = sshbuf_dup_string(b)) == NULL) 493 fatal_f("sshbuf_dup_string failed"); 494 sshbuf_free(b); 495 return list; 496 } 497 498 static Authmethod * 499 authmethod_lookup(Authctxt *authctxt, const char *name) 500 { 501 int i; 502 503 if (name != NULL) 504 for (i = 0; authmethods[i] != NULL; i++) 505 if (authmethods[i]->enabled != NULL && 506 *(authmethods[i]->enabled) != 0 && 507 strcmp(name, authmethods[i]->name) == 0 && 508 auth2_method_allowed(authctxt, 509 authmethods[i]->name, NULL)) 510 return authmethods[i]; 511 debug2("Unrecognized authentication method name: %s", 512 name ? name : "NULL"); 513 return NULL; 514 } 515 516 /* 517 * Check a comma-separated list of methods for validity. Is need_enable is 518 * non-zero, then also require that the methods are enabled. 519 * Returns 0 on success or -1 if the methods list is invalid. 520 */ 521 int 522 auth2_methods_valid(const char *_methods, int need_enable) 523 { 524 char *methods, *omethods, *method, *p; 525 u_int i, found; 526 int ret = -1; 527 528 if (*_methods == '\0') { 529 error("empty authentication method list"); 530 return -1; 531 } 532 omethods = methods = xstrdup(_methods); 533 while ((method = strsep(&methods, ",")) != NULL) { 534 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 535 if ((p = strchr(method, ':')) != NULL) 536 *p = '\0'; 537 if (strcmp(method, authmethods[i]->name) != 0) 538 continue; 539 if (need_enable) { 540 if (authmethods[i]->enabled == NULL || 541 *(authmethods[i]->enabled) == 0) { 542 error("Disabled method \"%s\" in " 543 "AuthenticationMethods list \"%s\"", 544 method, _methods); 545 goto out; 546 } 547 } 548 found = 1; 549 break; 550 } 551 if (!found) { 552 error("Unknown authentication method \"%s\" in list", 553 method); 554 goto out; 555 } 556 } 557 ret = 0; 558 out: 559 free(omethods); 560 return ret; 561 } 562 563 /* 564 * Prune the AuthenticationMethods supplied in the configuration, removing 565 * any methods lists that include disabled methods. Note that this might 566 * leave authctxt->num_auth_methods == 0, even when multiple required auth 567 * has been requested. For this reason, all tests for whether multiple is 568 * enabled should consult options.num_auth_methods directly. 569 */ 570 int 571 auth2_setup_methods_lists(Authctxt *authctxt) 572 { 573 u_int i; 574 575 /* First, normalise away the "any" pseudo-method */ 576 if (options.num_auth_methods == 1 && 577 strcmp(options.auth_methods[0], "any") == 0) { 578 free(options.auth_methods[0]); 579 options.auth_methods[0] = NULL; 580 options.num_auth_methods = 0; 581 } 582 583 if (options.num_auth_methods == 0) 584 return 0; 585 debug3_f("checking methods"); 586 authctxt->auth_methods = xcalloc(options.num_auth_methods, 587 sizeof(*authctxt->auth_methods)); 588 authctxt->num_auth_methods = 0; 589 for (i = 0; i < options.num_auth_methods; i++) { 590 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 591 logit("Authentication methods list \"%s\" contains " 592 "disabled method, skipping", 593 options.auth_methods[i]); 594 continue; 595 } 596 debug("authentication methods list %d: %s", 597 authctxt->num_auth_methods, options.auth_methods[i]); 598 authctxt->auth_methods[authctxt->num_auth_methods++] = 599 xstrdup(options.auth_methods[i]); 600 } 601 if (authctxt->num_auth_methods == 0) { 602 error("No AuthenticationMethods left after eliminating " 603 "disabled methods"); 604 return -1; 605 } 606 return 0; 607 } 608 609 static int 610 list_starts_with(const char *methods, const char *method, 611 const char *submethod) 612 { 613 size_t l = strlen(method); 614 int match; 615 const char *p; 616 617 if (strncmp(methods, method, l) != 0) 618 return MATCH_NONE; 619 p = methods + l; 620 match = MATCH_METHOD; 621 if (*p == ':') { 622 if (!submethod) 623 return MATCH_PARTIAL; 624 l = strlen(submethod); 625 p += 1; 626 if (strncmp(submethod, p, l)) 627 return MATCH_NONE; 628 p += l; 629 match = MATCH_BOTH; 630 } 631 if (*p != ',' && *p != '\0') 632 return MATCH_NONE; 633 return match; 634 } 635 636 /* 637 * Remove method from the start of a comma-separated list of methods. 638 * Returns 0 if the list of methods did not start with that method or 1 639 * if it did. 640 */ 641 static int 642 remove_method(char **methods, const char *method, const char *submethod) 643 { 644 char *omethods = *methods, *p; 645 size_t l = strlen(method); 646 int match; 647 648 match = list_starts_with(omethods, method, submethod); 649 if (match != MATCH_METHOD && match != MATCH_BOTH) 650 return 0; 651 p = omethods + l; 652 if (submethod && match == MATCH_BOTH) 653 p += 1 + strlen(submethod); /* include colon */ 654 if (*p == ',') 655 p++; 656 *methods = xstrdup(p); 657 free(omethods); 658 return 1; 659 } 660 661 /* 662 * Called after successful authentication. Will remove the successful method 663 * from the start of each list in which it occurs. If it was the last method 664 * in any list, then authentication is deemed successful. 665 * Returns 1 if the method completed any authentication list or 0 otherwise. 666 */ 667 int 668 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 669 const char *submethod) 670 { 671 u_int i, found = 0; 672 673 debug3_f("updating methods list after \"%s\"", method); 674 for (i = 0; i < authctxt->num_auth_methods; i++) { 675 if (!remove_method(&(authctxt->auth_methods[i]), method, 676 submethod)) 677 continue; 678 found = 1; 679 if (*authctxt->auth_methods[i] == '\0') { 680 debug2("authentication methods list %d complete", i); 681 return 1; 682 } 683 debug3("authentication methods list %d remaining: \"%s\"", 684 i, authctxt->auth_methods[i]); 685 } 686 /* This should not happen, but would be bad if it did */ 687 if (!found) 688 fatal_f("method not in AuthenticationMethods"); 689 return 0; 690 } 691 692 /* Reset method-specific information */ 693 void auth2_authctxt_reset_info(Authctxt *authctxt) 694 { 695 sshkey_free(authctxt->auth_method_key); 696 free(authctxt->auth_method_info); 697 authctxt->auth_method_key = NULL; 698 authctxt->auth_method_info = NULL; 699 } 700 701 /* Record auth method-specific information for logs */ 702 void 703 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 704 { 705 va_list ap; 706 int i; 707 708 free(authctxt->auth_method_info); 709 authctxt->auth_method_info = NULL; 710 711 va_start(ap, fmt); 712 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 713 va_end(ap); 714 715 if (i == -1) 716 fatal_f("vasprintf failed"); 717 } 718 719 /* 720 * Records a public key used in authentication. This is used for logging 721 * and to ensure that the same key is not subsequently accepted again for 722 * multiple authentication. 723 */ 724 void 725 auth2_record_key(Authctxt *authctxt, int authenticated, 726 const struct sshkey *key) 727 { 728 struct sshkey **tmp, *dup; 729 int r; 730 731 if ((r = sshkey_from_private(key, &dup)) != 0) 732 fatal_fr(r, "copy key"); 733 sshkey_free(authctxt->auth_method_key); 734 authctxt->auth_method_key = dup; 735 736 if (!authenticated) 737 return; 738 739 /* If authenticated, make sure we don't accept this key again */ 740 if ((r = sshkey_from_private(key, &dup)) != 0) 741 fatal_fr(r, "copy key"); 742 if (authctxt->nprev_keys >= INT_MAX || 743 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 744 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 745 fatal_f("reallocarray failed"); 746 authctxt->prev_keys = tmp; 747 authctxt->prev_keys[authctxt->nprev_keys] = dup; 748 authctxt->nprev_keys++; 749 750 } 751 752 /* Checks whether a key has already been previously used for authentication */ 753 int 754 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 755 { 756 u_int i; 757 char *fp; 758 759 for (i = 0; i < authctxt->nprev_keys; i++) { 760 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 761 fp = sshkey_fingerprint(authctxt->prev_keys[i], 762 options.fingerprint_hash, SSH_FP_DEFAULT); 763 debug3_f("key already used: %s %s", 764 sshkey_type(authctxt->prev_keys[i]), 765 fp == NULL ? "UNKNOWN" : fp); 766 free(fp); 767 return 1; 768 } 769 } 770 return 0; 771 } 772 773 /* 774 * Updates authctxt->session_info with details of authentication. Should be 775 * whenever an authentication method succeeds. 776 */ 777 void 778 auth2_update_session_info(Authctxt *authctxt, const char *method, 779 const char *submethod) 780 { 781 int r; 782 783 if (authctxt->session_info == NULL) { 784 if ((authctxt->session_info = sshbuf_new()) == NULL) 785 fatal_f("sshbuf_new"); 786 } 787 788 /* Append method[/submethod] */ 789 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 790 method, submethod == NULL ? "" : "/", 791 submethod == NULL ? "" : submethod)) != 0) 792 fatal_fr(r, "append method"); 793 794 /* Append key if present */ 795 if (authctxt->auth_method_key != NULL) { 796 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 797 (r = sshkey_format_text(authctxt->auth_method_key, 798 authctxt->session_info)) != 0) 799 fatal_fr(r, "append key"); 800 } 801 802 if (authctxt->auth_method_info != NULL) { 803 /* Ensure no ambiguity here */ 804 if (strchr(authctxt->auth_method_info, '\n') != NULL) 805 fatal_f("auth_method_info contains \\n"); 806 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 807 (r = sshbuf_putf(authctxt->session_info, "%s", 808 authctxt->auth_method_info)) != 0) { 809 fatal_fr(r, "append method info"); 810 } 811 } 812 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 813 fatal_fr(r, "append"); 814 } 815 816