1 /* $OpenBSD: auth2.c,v 1.168 2023/12/18 14:45:49 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 <sys/types.h> 27 #include <sys/stat.h> 28 #include <sys/uio.h> 29 30 #include <fcntl.h> 31 #include <limits.h> 32 #include <pwd.h> 33 #include <stdarg.h> 34 #include <string.h> 35 #include <unistd.h> 36 #include <time.h> 37 38 #include "stdlib.h" 39 #include "atomicio.h" 40 #include "xmalloc.h" 41 #include "ssh2.h" 42 #include "packet.h" 43 #include "log.h" 44 #include "sshbuf.h" 45 #include "misc.h" 46 #include "servconf.h" 47 #include "sshkey.h" 48 #include "hostfile.h" 49 #include "auth.h" 50 #include "dispatch.h" 51 #include "pathnames.h" 52 #ifdef GSSAPI 53 #include "ssh-gss.h" 54 #endif 55 #include "monitor_wrap.h" 56 #include "ssherr.h" 57 #include "digest.h" 58 #include "kex.h" 59 60 /* import */ 61 extern ServerOptions options; 62 63 /* methods */ 64 65 extern Authmethod method_none; 66 extern Authmethod method_pubkey; 67 extern Authmethod method_passwd; 68 extern Authmethod method_kbdint; 69 extern Authmethod method_hostbased; 70 #ifdef GSSAPI 71 extern Authmethod method_gssapi; 72 #endif 73 74 Authmethod *authmethods[] = { 75 &method_none, 76 &method_pubkey, 77 #ifdef GSSAPI 78 &method_gssapi, 79 #endif 80 &method_passwd, 81 &method_kbdint, 82 &method_hostbased, 83 NULL 84 }; 85 86 /* protocol */ 87 88 static int input_service_request(int, u_int32_t, struct ssh *); 89 static int input_userauth_request(int, u_int32_t, struct ssh *); 90 91 /* helper */ 92 static Authmethod *authmethod_byname(const char *); 93 static Authmethod *authmethod_lookup(Authctxt *, const char *); 94 static char *authmethods_get(Authctxt *authctxt); 95 96 #define MATCH_NONE 0 /* method or submethod mismatch */ 97 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 98 #define MATCH_BOTH 2 /* method and submethod match */ 99 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 100 static int list_starts_with(const char *, const char *, const char *); 101 102 char * 103 auth2_read_banner(void) 104 { 105 struct stat st; 106 char *banner = NULL; 107 size_t len, n; 108 int fd; 109 110 if ((fd = open(options.banner, O_RDONLY)) == -1) 111 return (NULL); 112 if (fstat(fd, &st) == -1) { 113 close(fd); 114 return (NULL); 115 } 116 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 117 close(fd); 118 return (NULL); 119 } 120 121 len = (size_t)st.st_size; /* truncate */ 122 banner = xmalloc(len + 1); 123 n = atomicio(read, fd, banner, len); 124 close(fd); 125 126 if (n != len) { 127 free(banner); 128 return (NULL); 129 } 130 banner[n] = '\0'; 131 132 return (banner); 133 } 134 135 static void 136 userauth_banner(struct ssh *ssh) 137 { 138 char *banner = NULL; 139 int r; 140 141 if (options.banner == NULL) 142 return; 143 144 if ((banner = PRIVSEP(auth2_read_banner())) == NULL) 145 goto done; 146 147 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 || 148 (r = sshpkt_put_cstring(ssh, banner)) != 0 || 149 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */ 150 (r = sshpkt_send(ssh)) != 0) 151 fatal_fr(r, "send packet"); 152 debug("userauth_banner: sent"); 153 done: 154 free(banner); 155 } 156 157 /* 158 * loop until authctxt->success == TRUE 159 */ 160 void 161 do_authentication2(struct ssh *ssh) 162 { 163 Authctxt *authctxt = ssh->authctxt; 164 165 ssh_dispatch_init(ssh, &dispatch_protocol_error); 166 if (ssh->kex->ext_info_c) 167 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_input_ext_info); 168 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); 169 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); 170 ssh->authctxt = NULL; 171 } 172 173 static int 174 input_service_request(int type, u_int32_t seq, struct ssh *ssh) 175 { 176 Authctxt *authctxt = ssh->authctxt; 177 char *service = NULL; 178 int r, acceptit = 0; 179 180 if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 181 (r = sshpkt_get_end(ssh)) != 0) 182 goto out; 183 184 if (authctxt == NULL) 185 fatal("input_service_request: no authctxt"); 186 187 if (strcmp(service, "ssh-userauth") == 0) { 188 if (!authctxt->success) { 189 acceptit = 1; 190 /* now we can handle user-auth requests */ 191 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 192 &input_userauth_request); 193 } 194 } 195 /* XXX all other service requests are denied */ 196 197 if (acceptit) { 198 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 || 199 (r = sshpkt_put_cstring(ssh, service)) != 0 || 200 (r = sshpkt_send(ssh)) != 0 || 201 (r = ssh_packet_write_wait(ssh)) != 0) 202 goto out; 203 } else { 204 debug("bad service request %s", service); 205 ssh_packet_disconnect(ssh, "bad service request %s", service); 206 } 207 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &dispatch_protocol_error); 208 r = 0; 209 out: 210 free(service); 211 return r; 212 } 213 214 #define MIN_FAIL_DELAY_SECONDS 0.005 215 #define MAX_FAIL_DELAY_SECONDS 5.0 216 static double 217 user_specific_delay(const char *user) 218 { 219 char b[512]; 220 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 221 u_char *hash = xmalloc(len); 222 double delay; 223 224 (void)snprintf(b, sizeof b, "%llu%s", 225 (unsigned long long)options.timing_secret, user); 226 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 227 fatal_f("ssh_digest_memory"); 228 /* 0-4.2 ms of delay */ 229 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 230 freezero(hash, len); 231 debug3_f("user specific delay %0.3lfms", delay/1000); 232 return MIN_FAIL_DELAY_SECONDS + delay; 233 } 234 235 static void 236 ensure_minimum_time_since(double start, double seconds) 237 { 238 struct timespec ts; 239 double elapsed = monotime_double() - start, req = seconds, remain; 240 241 if (elapsed > MAX_FAIL_DELAY_SECONDS) { 242 debug3_f("elapsed %0.3lfms exceeded the max delay " 243 "requested %0.3lfms)", elapsed*1000, req*1000); 244 return; 245 } 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 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 286 authctxt->valid = 1; 287 debug2_f("setting up authctxt for %s", user); 288 } else { 289 authctxt->valid = 0; 290 /* Invalid user, fake password information */ 291 authctxt->pw = fakepw(); 292 } 293 ssh_packet_set_log_preamble(ssh, "%suser %s", 294 authctxt->valid ? "authenticating " : "invalid ", user); 295 setproctitle("%s%s", authctxt->valid ? user : "unknown", 296 use_privsep ? " [net]" : ""); 297 authctxt->user = xstrdup(user); 298 authctxt->service = xstrdup(service); 299 authctxt->style = style ? xstrdup(style) : NULL; 300 if (use_privsep) 301 mm_inform_authserv(service, style); 302 userauth_banner(ssh); 303 if ((r = kex_server_update_ext_info(ssh)) != 0) 304 fatal_fr(r, "kex_server_update_ext_info failed"); 305 if (auth2_setup_methods_lists(authctxt) != 0) 306 ssh_packet_disconnect(ssh, 307 "no authentication methods enabled"); 308 } else if (strcmp(user, authctxt->user) != 0 || 309 strcmp(service, authctxt->service) != 0) { 310 ssh_packet_disconnect(ssh, "Change of username or service " 311 "not allowed: (%s,%s) -> (%s,%s)", 312 authctxt->user, authctxt->service, user, service); 313 } 314 /* reset state */ 315 auth2_challenge_stop(ssh); 316 317 #ifdef GSSAPI 318 /* XXX move to auth2_gssapi_stop() */ 319 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 320 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 321 #endif 322 323 auth2_authctxt_reset_info(authctxt); 324 authctxt->postponed = 0; 325 authctxt->server_caused_failure = 0; 326 327 /* try to authenticate user */ 328 m = authmethod_lookup(authctxt, method); 329 if (m != NULL && authctxt->failures < options.max_authtries) { 330 debug2("input_userauth_request: try method %s", method); 331 authenticated = m->userauth(ssh, method); 332 } 333 if (!authctxt->authenticated && strcmp(method, "none") != 0) 334 ensure_minimum_time_since(tstart, 335 user_specific_delay(authctxt->user)); 336 userauth_finish(ssh, authenticated, method, NULL); 337 r = 0; 338 out: 339 free(service); 340 free(user); 341 free(method); 342 return r; 343 } 344 345 void 346 userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method, 347 const char *submethod) 348 { 349 Authctxt *authctxt = ssh->authctxt; 350 Authmethod *m = NULL; 351 const char *method = packet_method; 352 char *methods; 353 int r, partial = 0; 354 355 if (authenticated) { 356 if (!authctxt->valid) { 357 fatal("INTERNAL ERROR: authenticated invalid user %s", 358 authctxt->user); 359 } 360 if (authctxt->postponed) 361 fatal("INTERNAL ERROR: authenticated and postponed"); 362 /* prefer primary authmethod name to possible synonym */ 363 if ((m = authmethod_byname(method)) == NULL) 364 fatal("INTERNAL ERROR: bad method %s", method); 365 method = m->name; 366 } 367 368 /* Special handling for root */ 369 if (authenticated && authctxt->pw->pw_uid == 0 && 370 !auth_root_allowed(ssh, method)) 371 authenticated = 0; 372 373 if (authenticated && options.num_auth_methods != 0) { 374 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 375 authenticated = 0; 376 partial = 1; 377 } 378 } 379 380 /* Log before sending the reply */ 381 auth_log(ssh, authenticated, partial, method, submethod); 382 383 /* Update information exposed to session */ 384 if (authenticated || partial) 385 auth2_update_session_info(authctxt, method, submethod); 386 387 if (authctxt->postponed) 388 return; 389 390 if (authenticated == 1) { 391 /* turn off userauth */ 392 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 393 &dispatch_protocol_ignore); 394 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 395 (r = sshpkt_send(ssh)) != 0 || 396 (r = ssh_packet_write_wait(ssh)) != 0) 397 fatal_fr(r, "send success packet"); 398 /* now we can break out */ 399 authctxt->success = 1; 400 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 401 } else { 402 /* Allow initial try of "none" auth without failure penalty */ 403 if (!partial && !authctxt->server_caused_failure && 404 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) 405 authctxt->failures++; 406 if (authctxt->failures >= options.max_authtries) 407 auth_maxtries_exceeded(ssh); 408 methods = authmethods_get(authctxt); 409 debug3_f("failure partial=%d next methods=\"%s\"", 410 partial, methods); 411 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 412 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 413 (r = sshpkt_put_u8(ssh, partial)) != 0 || 414 (r = sshpkt_send(ssh)) != 0 || 415 (r = ssh_packet_write_wait(ssh)) != 0) 416 fatal_fr(r, "send failure packet"); 417 free(methods); 418 } 419 } 420 421 /* 422 * Checks whether method is allowed by at least one AuthenticationMethods 423 * methods list. Returns 1 if allowed, or no methods lists configured. 424 * 0 otherwise. 425 */ 426 int 427 auth2_method_allowed(Authctxt *authctxt, const char *method, 428 const char *submethod) 429 { 430 u_int i; 431 432 /* 433 * NB. authctxt->num_auth_methods might be zero as a result of 434 * auth2_setup_methods_lists(), so check the configuration. 435 */ 436 if (options.num_auth_methods == 0) 437 return 1; 438 for (i = 0; i < authctxt->num_auth_methods; i++) { 439 if (list_starts_with(authctxt->auth_methods[i], method, 440 submethod) != MATCH_NONE) 441 return 1; 442 } 443 return 0; 444 } 445 446 static char * 447 authmethods_get(Authctxt *authctxt) 448 { 449 struct sshbuf *b; 450 char *list; 451 int i, r; 452 453 if ((b = sshbuf_new()) == NULL) 454 fatal_f("sshbuf_new failed"); 455 for (i = 0; authmethods[i] != NULL; i++) { 456 if (strcmp(authmethods[i]->name, "none") == 0) 457 continue; 458 if (authmethods[i]->enabled == NULL || 459 *(authmethods[i]->enabled) == 0) 460 continue; 461 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 462 NULL)) 463 continue; 464 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 465 authmethods[i]->name)) != 0) 466 fatal_fr(r, "buffer error"); 467 } 468 if ((list = sshbuf_dup_string(b)) == NULL) 469 fatal_f("sshbuf_dup_string failed"); 470 sshbuf_free(b); 471 return list; 472 } 473 474 static Authmethod * 475 authmethod_byname(const char *name) 476 { 477 int i; 478 479 if (name == NULL) 480 fatal_f("NULL authentication method name"); 481 for (i = 0; authmethods[i] != NULL; i++) { 482 if (strcmp(name, authmethods[i]->name) == 0 || 483 (authmethods[i]->synonym != NULL && 484 strcmp(name, authmethods[i]->synonym) == 0)) 485 return authmethods[i]; 486 } 487 debug_f("unrecognized authentication method name: %s", name); 488 return NULL; 489 } 490 491 static Authmethod * 492 authmethod_lookup(Authctxt *authctxt, const char *name) 493 { 494 Authmethod *method; 495 496 if ((method = authmethod_byname(name)) == NULL) 497 return NULL; 498 499 if (method->enabled == NULL || *(method->enabled) == 0) { 500 debug3_f("method %s not enabled", name); 501 return NULL; 502 } 503 if (!auth2_method_allowed(authctxt, method->name, NULL)) { 504 debug3_f("method %s not allowed " 505 "by AuthenticationMethods", name); 506 return NULL; 507 } 508 return method; 509 } 510 511 /* 512 * Check a comma-separated list of methods for validity. Is need_enable is 513 * non-zero, then also require that the methods are enabled. 514 * Returns 0 on success or -1 if the methods list is invalid. 515 */ 516 int 517 auth2_methods_valid(const char *_methods, int need_enable) 518 { 519 char *methods, *omethods, *method, *p; 520 u_int i, found; 521 int ret = -1; 522 523 if (*_methods == '\0') { 524 error("empty authentication method list"); 525 return -1; 526 } 527 omethods = methods = xstrdup(_methods); 528 while ((method = strsep(&methods, ",")) != NULL) { 529 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 530 if ((p = strchr(method, ':')) != NULL) 531 *p = '\0'; 532 if (strcmp(method, authmethods[i]->name) != 0) 533 continue; 534 if (need_enable) { 535 if (authmethods[i]->enabled == NULL || 536 *(authmethods[i]->enabled) == 0) { 537 error("Disabled method \"%s\" in " 538 "AuthenticationMethods list \"%s\"", 539 method, _methods); 540 goto out; 541 } 542 } 543 found = 1; 544 break; 545 } 546 if (!found) { 547 error("Unknown authentication method \"%s\" in list", 548 method); 549 goto out; 550 } 551 } 552 ret = 0; 553 out: 554 free(omethods); 555 return ret; 556 } 557 558 /* 559 * Prune the AuthenticationMethods supplied in the configuration, removing 560 * any methods lists that include disabled methods. Note that this might 561 * leave authctxt->num_auth_methods == 0, even when multiple required auth 562 * has been requested. For this reason, all tests for whether multiple is 563 * enabled should consult options.num_auth_methods directly. 564 */ 565 int 566 auth2_setup_methods_lists(Authctxt *authctxt) 567 { 568 u_int i; 569 570 /* First, normalise away the "any" pseudo-method */ 571 if (options.num_auth_methods == 1 && 572 strcmp(options.auth_methods[0], "any") == 0) { 573 free(options.auth_methods[0]); 574 options.auth_methods[0] = NULL; 575 options.num_auth_methods = 0; 576 } 577 578 if (options.num_auth_methods == 0) 579 return 0; 580 debug3_f("checking methods"); 581 authctxt->auth_methods = xcalloc(options.num_auth_methods, 582 sizeof(*authctxt->auth_methods)); 583 authctxt->num_auth_methods = 0; 584 for (i = 0; i < options.num_auth_methods; i++) { 585 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 586 logit("Authentication methods list \"%s\" contains " 587 "disabled method, skipping", 588 options.auth_methods[i]); 589 continue; 590 } 591 debug("authentication methods list %d: %s", 592 authctxt->num_auth_methods, options.auth_methods[i]); 593 authctxt->auth_methods[authctxt->num_auth_methods++] = 594 xstrdup(options.auth_methods[i]); 595 } 596 if (authctxt->num_auth_methods == 0) { 597 error("No AuthenticationMethods left after eliminating " 598 "disabled methods"); 599 return -1; 600 } 601 return 0; 602 } 603 604 static int 605 list_starts_with(const char *methods, const char *method, 606 const char *submethod) 607 { 608 size_t l = strlen(method); 609 int match; 610 const char *p; 611 612 if (strncmp(methods, method, l) != 0) 613 return MATCH_NONE; 614 p = methods + l; 615 match = MATCH_METHOD; 616 if (*p == ':') { 617 if (!submethod) 618 return MATCH_PARTIAL; 619 l = strlen(submethod); 620 p += 1; 621 if (strncmp(submethod, p, l)) 622 return MATCH_NONE; 623 p += l; 624 match = MATCH_BOTH; 625 } 626 if (*p != ',' && *p != '\0') 627 return MATCH_NONE; 628 return match; 629 } 630 631 /* 632 * Remove method from the start of a comma-separated list of methods. 633 * Returns 0 if the list of methods did not start with that method or 1 634 * if it did. 635 */ 636 static int 637 remove_method(char **methods, const char *method, const char *submethod) 638 { 639 char *omethods = *methods, *p; 640 size_t l = strlen(method); 641 int match; 642 643 match = list_starts_with(omethods, method, submethod); 644 if (match != MATCH_METHOD && match != MATCH_BOTH) 645 return 0; 646 p = omethods + l; 647 if (submethod && match == MATCH_BOTH) 648 p += 1 + strlen(submethod); /* include colon */ 649 if (*p == ',') 650 p++; 651 *methods = xstrdup(p); 652 free(omethods); 653 return 1; 654 } 655 656 /* 657 * Called after successful authentication. Will remove the successful method 658 * from the start of each list in which it occurs. If it was the last method 659 * in any list, then authentication is deemed successful. 660 * Returns 1 if the method completed any authentication list or 0 otherwise. 661 */ 662 int 663 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 664 const char *submethod) 665 { 666 u_int i, found = 0; 667 668 debug3_f("updating methods list after \"%s\"", method); 669 for (i = 0; i < authctxt->num_auth_methods; i++) { 670 if (!remove_method(&(authctxt->auth_methods[i]), method, 671 submethod)) 672 continue; 673 found = 1; 674 if (*authctxt->auth_methods[i] == '\0') { 675 debug2("authentication methods list %d complete", i); 676 return 1; 677 } 678 debug3("authentication methods list %d remaining: \"%s\"", 679 i, authctxt->auth_methods[i]); 680 } 681 /* This should not happen, but would be bad if it did */ 682 if (!found) 683 fatal_f("method not in AuthenticationMethods"); 684 return 0; 685 } 686 687 /* Reset method-specific information */ 688 void auth2_authctxt_reset_info(Authctxt *authctxt) 689 { 690 sshkey_free(authctxt->auth_method_key); 691 free(authctxt->auth_method_info); 692 authctxt->auth_method_key = NULL; 693 authctxt->auth_method_info = NULL; 694 } 695 696 /* Record auth method-specific information for logs */ 697 void 698 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 699 { 700 va_list ap; 701 int i; 702 703 free(authctxt->auth_method_info); 704 authctxt->auth_method_info = NULL; 705 706 va_start(ap, fmt); 707 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 708 va_end(ap); 709 710 if (i == -1) 711 fatal_f("vasprintf failed"); 712 } 713 714 /* 715 * Records a public key used in authentication. This is used for logging 716 * and to ensure that the same key is not subsequently accepted again for 717 * multiple authentication. 718 */ 719 void 720 auth2_record_key(Authctxt *authctxt, int authenticated, 721 const struct sshkey *key) 722 { 723 struct sshkey **tmp, *dup; 724 int r; 725 726 if ((r = sshkey_from_private(key, &dup)) != 0) 727 fatal_fr(r, "copy key"); 728 sshkey_free(authctxt->auth_method_key); 729 authctxt->auth_method_key = dup; 730 731 if (!authenticated) 732 return; 733 734 /* If authenticated, make sure we don't accept this key again */ 735 if ((r = sshkey_from_private(key, &dup)) != 0) 736 fatal_fr(r, "copy key"); 737 if (authctxt->nprev_keys >= INT_MAX || 738 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 739 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 740 fatal_f("reallocarray failed"); 741 authctxt->prev_keys = tmp; 742 authctxt->prev_keys[authctxt->nprev_keys] = dup; 743 authctxt->nprev_keys++; 744 745 } 746 747 /* Checks whether a key has already been previously used for authentication */ 748 int 749 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 750 { 751 u_int i; 752 char *fp; 753 754 for (i = 0; i < authctxt->nprev_keys; i++) { 755 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 756 fp = sshkey_fingerprint(authctxt->prev_keys[i], 757 options.fingerprint_hash, SSH_FP_DEFAULT); 758 debug3_f("key already used: %s %s", 759 sshkey_type(authctxt->prev_keys[i]), 760 fp == NULL ? "UNKNOWN" : fp); 761 free(fp); 762 return 1; 763 } 764 } 765 return 0; 766 } 767 768 /* 769 * Updates authctxt->session_info with details of authentication. Should be 770 * whenever an authentication method succeeds. 771 */ 772 void 773 auth2_update_session_info(Authctxt *authctxt, const char *method, 774 const char *submethod) 775 { 776 int r; 777 778 if (authctxt->session_info == NULL) { 779 if ((authctxt->session_info = sshbuf_new()) == NULL) 780 fatal_f("sshbuf_new"); 781 } 782 783 /* Append method[/submethod] */ 784 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 785 method, submethod == NULL ? "" : "/", 786 submethod == NULL ? "" : submethod)) != 0) 787 fatal_fr(r, "append method"); 788 789 /* Append key if present */ 790 if (authctxt->auth_method_key != NULL) { 791 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 792 (r = sshkey_format_text(authctxt->auth_method_key, 793 authctxt->session_info)) != 0) 794 fatal_fr(r, "append key"); 795 } 796 797 if (authctxt->auth_method_info != NULL) { 798 /* Ensure no ambiguity here */ 799 if (strchr(authctxt->auth_method_info, '\n') != NULL) 800 fatal_f("auth_method_info contains \\n"); 801 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 802 (r = sshbuf_putf(authctxt->session_info, "%s", 803 authctxt->auth_method_info)) != 0) { 804 fatal_fr(r, "append method info"); 805 } 806 } 807 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 808 fatal_fr(r, "append"); 809 } 810 811