1 /* $OpenBSD: auth2.c,v 1.169 2024/05/17 00:30:23 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 "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 #include "kex.h" 62 63 /* import */ 64 extern ServerOptions options; 65 extern struct sshbuf *loginmsg; 66 67 /* methods */ 68 69 extern Authmethod method_none; 70 extern Authmethod method_pubkey; 71 extern Authmethod method_passwd; 72 extern Authmethod method_kbdint; 73 extern Authmethod method_hostbased; 74 #ifdef GSSAPI 75 extern Authmethod method_gssapi; 76 #endif 77 78 Authmethod *authmethods[] = { 79 &method_none, 80 &method_pubkey, 81 #ifdef GSSAPI 82 &method_gssapi, 83 #endif 84 &method_passwd, 85 &method_kbdint, 86 &method_hostbased, 87 NULL 88 }; 89 90 /* protocol */ 91 92 static int input_service_request(int, u_int32_t, struct ssh *); 93 static int input_userauth_request(int, u_int32_t, struct ssh *); 94 95 /* helper */ 96 static Authmethod *authmethod_byname(const char *); 97 static Authmethod *authmethod_lookup(Authctxt *, const char *); 98 static char *authmethods_get(Authctxt *authctxt); 99 100 #define MATCH_NONE 0 /* method or submethod mismatch */ 101 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 102 #define MATCH_BOTH 2 /* method and submethod match */ 103 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 104 static int list_starts_with(const char *, const char *, const char *); 105 106 char * 107 auth2_read_banner(void) 108 { 109 struct stat st; 110 char *banner = NULL; 111 size_t len, n; 112 int fd; 113 114 if ((fd = open(options.banner, O_RDONLY)) == -1) 115 return (NULL); 116 if (fstat(fd, &st) == -1) { 117 close(fd); 118 return (NULL); 119 } 120 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 121 close(fd); 122 return (NULL); 123 } 124 125 len = (size_t)st.st_size; /* truncate */ 126 banner = xmalloc(len + 1); 127 n = atomicio(read, fd, banner, len); 128 close(fd); 129 130 if (n != len) { 131 free(banner); 132 return (NULL); 133 } 134 banner[n] = '\0'; 135 136 return (banner); 137 } 138 139 static void 140 userauth_send_banner(struct ssh *ssh, const char *msg) 141 { 142 int r; 143 144 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 || 145 (r = sshpkt_put_cstring(ssh, msg)) != 0 || 146 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */ 147 (r = sshpkt_send(ssh)) != 0) 148 fatal_fr(r, "send packet"); 149 debug("%s: sent", __func__); 150 } 151 152 static void 153 userauth_banner(struct ssh *ssh) 154 { 155 char *banner = NULL; 156 157 if (options.banner == NULL) 158 return; 159 160 if ((banner = mm_auth2_read_banner()) == NULL) 161 goto done; 162 userauth_send_banner(ssh, banner); 163 164 done: 165 free(banner); 166 } 167 168 /* 169 * loop until authctxt->success == TRUE 170 */ 171 void 172 do_authentication2(struct ssh *ssh) 173 { 174 Authctxt *authctxt = ssh->authctxt; 175 176 ssh_dispatch_init(ssh, &dispatch_protocol_error); 177 if (ssh->kex->ext_info_c) 178 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_input_ext_info); 179 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); 180 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); 181 ssh->authctxt = NULL; 182 } 183 184 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 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &dispatch_protocol_error); 219 r = 0; 220 out: 221 free(service); 222 return r; 223 } 224 225 #define MIN_FAIL_DELAY_SECONDS 0.005 226 #define MAX_FAIL_DELAY_SECONDS 5.0 227 static double 228 user_specific_delay(const char *user) 229 { 230 char b[512]; 231 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 232 u_char *hash = xmalloc(len); 233 double delay; 234 235 (void)snprintf(b, sizeof b, "%llu%s", 236 (unsigned long long)options.timing_secret, user); 237 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 238 fatal_f("ssh_digest_memory"); 239 /* 0-4.2 ms of delay */ 240 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 241 freezero(hash, len); 242 debug3_f("user specific delay %0.3lfms", delay/1000); 243 return MIN_FAIL_DELAY_SECONDS + delay; 244 } 245 246 static void 247 ensure_minimum_time_since(double start, double seconds) 248 { 249 struct timespec ts; 250 double elapsed = monotime_double() - start, req = seconds, remain; 251 252 if (elapsed > MAX_FAIL_DELAY_SECONDS) { 253 debug3_f("elapsed %0.3lfms exceeded the max delay " 254 "requested %0.3lfms)", elapsed*1000, req*1000); 255 return; 256 } 257 258 /* if we've already passed the requested time, scale up */ 259 while ((remain = seconds - elapsed) < 0.0) 260 seconds *= 2; 261 262 ts.tv_sec = remain; 263 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; 264 debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 265 elapsed*1000, remain*1000, req*1000); 266 nanosleep(&ts, NULL); 267 } 268 269 static int 270 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 271 { 272 Authctxt *authctxt = ssh->authctxt; 273 Authmethod *m = NULL; 274 char *user = NULL, *service = NULL, *method = NULL, *style = NULL; 275 int r, authenticated = 0; 276 double tstart = monotime_double(); 277 278 if (authctxt == NULL) 279 fatal("input_userauth_request: no authctxt"); 280 281 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || 282 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 283 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) 284 goto out; 285 debug("userauth-request for user %s service %s method %s", user, service, method); 286 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 287 288 if ((style = strchr(user, ':')) != NULL) 289 *style++ = 0; 290 291 if (authctxt->attempt >= 1024) 292 auth_maxtries_exceeded(ssh); 293 if (authctxt->attempt++ == 0) { 294 /* setup auth context */ 295 authctxt->pw = mm_getpwnamallow(ssh, user); 296 authctxt->user = xstrdup(user); 297 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 298 authctxt->valid = 1; 299 debug2_f("setting up authctxt for %s", user); 300 } else { 301 authctxt->valid = 0; 302 /* Invalid user, fake password information */ 303 authctxt->pw = fakepw(); 304 #ifdef SSH_AUDIT_EVENTS 305 mm_audit_event(ssh, SSH_INVALID_USER); 306 #endif 307 } 308 #ifdef USE_PAM 309 if (options.use_pam) 310 mm_start_pam(ssh); 311 #endif 312 ssh_packet_set_log_preamble(ssh, "%suser %s", 313 authctxt->valid ? "authenticating " : "invalid ", user); 314 setproctitle("%s [net]", authctxt->valid ? user : "unknown"); 315 authctxt->service = xstrdup(service); 316 authctxt->style = style ? xstrdup(style) : NULL; 317 mm_inform_authserv(service, style); 318 userauth_banner(ssh); 319 if ((r = kex_server_update_ext_info(ssh)) != 0) 320 fatal_fr(r, "kex_server_update_ext_info failed"); 321 if (auth2_setup_methods_lists(authctxt) != 0) 322 ssh_packet_disconnect(ssh, 323 "no authentication methods enabled"); 324 } else if (strcmp(user, authctxt->user) != 0 || 325 strcmp(service, authctxt->service) != 0) { 326 ssh_packet_disconnect(ssh, "Change of username or service " 327 "not allowed: (%s,%s) -> (%s,%s)", 328 authctxt->user, authctxt->service, user, service); 329 } 330 /* reset state */ 331 auth2_challenge_stop(ssh); 332 333 #ifdef GSSAPI 334 /* XXX move to auth2_gssapi_stop() */ 335 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 336 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 337 #endif 338 339 auth2_authctxt_reset_info(authctxt); 340 authctxt->postponed = 0; 341 authctxt->server_caused_failure = 0; 342 343 /* try to authenticate user */ 344 m = authmethod_lookup(authctxt, method); 345 if (m != NULL && authctxt->failures < options.max_authtries) { 346 debug2("input_userauth_request: try method %s", method); 347 authenticated = m->userauth(ssh, method); 348 } 349 if (!authctxt->authenticated && strcmp(method, "none") != 0) 350 ensure_minimum_time_since(tstart, 351 user_specific_delay(authctxt->user)); 352 userauth_finish(ssh, authenticated, method, NULL); 353 r = 0; 354 out: 355 free(service); 356 free(user); 357 free(method); 358 return r; 359 } 360 361 void 362 userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method, 363 const char *submethod) 364 { 365 Authctxt *authctxt = ssh->authctxt; 366 Authmethod *m = NULL; 367 const char *method = packet_method; 368 char *methods; 369 int r, partial = 0; 370 371 if (authenticated) { 372 if (!authctxt->valid) { 373 fatal("INTERNAL ERROR: authenticated invalid user %s", 374 authctxt->user); 375 } 376 if (authctxt->postponed) 377 fatal("INTERNAL ERROR: authenticated and postponed"); 378 /* prefer primary authmethod name to possible synonym */ 379 if ((m = authmethod_byname(method)) == NULL) 380 fatal("INTERNAL ERROR: bad method %s", method); 381 method = m->cfg->name; 382 } 383 384 /* Special handling for root */ 385 if (authenticated && authctxt->pw->pw_uid == 0 && 386 !auth_root_allowed(ssh, method)) { 387 authenticated = 0; 388 #ifdef SSH_AUDIT_EVENTS 389 mm_audit_event(ssh, SSH_LOGIN_ROOT_DENIED); 390 #endif 391 } 392 393 if (authenticated && options.num_auth_methods != 0) { 394 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 395 authenticated = 0; 396 partial = 1; 397 } 398 } 399 400 /* Log before sending the reply */ 401 auth_log(ssh, authenticated, partial, method, submethod); 402 403 /* Update information exposed to session */ 404 if (authenticated || partial) 405 auth2_update_session_info(authctxt, method, submethod); 406 407 if (authctxt->postponed) 408 return; 409 410 #ifdef USE_PAM 411 if (options.use_pam && authenticated) { 412 int r, success = mm_do_pam_account(); 413 414 /* If PAM returned a message, send it to the user. */ 415 if (sshbuf_len(loginmsg) > 0) { 416 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0) 417 fatal("%s: buffer error: %s", 418 __func__, ssh_err(r)); 419 userauth_send_banner(ssh, sshbuf_ptr(loginmsg)); 420 if ((r = ssh_packet_write_wait(ssh)) != 0) { 421 sshpkt_fatal(ssh, r, 422 "%s: send PAM banner", __func__); 423 } 424 } 425 if (!success) { 426 fatal("Access denied for user %s by PAM account " 427 "configuration", authctxt->user); 428 } 429 } 430 #endif 431 432 if (authenticated == 1) { 433 /* turn off userauth */ 434 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 435 &dispatch_protocol_ignore); 436 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 437 (r = sshpkt_send(ssh)) != 0 || 438 (r = ssh_packet_write_wait(ssh)) != 0) 439 fatal_fr(r, "send success packet"); 440 /* now we can break out */ 441 authctxt->success = 1; 442 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 443 } else { 444 /* Allow initial try of "none" auth without failure penalty */ 445 if (!partial && !authctxt->server_caused_failure && 446 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) { 447 authctxt->failures++; 448 BLACKLIST_NOTIFY(ssh, BLACKLIST_AUTH_FAIL, "ssh"); 449 } 450 if (authctxt->failures >= options.max_authtries) { 451 #ifdef SSH_AUDIT_EVENTS 452 mm_audit_event(ssh, SSH_LOGIN_EXCEED_MAXTRIES); 453 #endif 454 auth_maxtries_exceeded(ssh); 455 } 456 methods = authmethods_get(authctxt); 457 debug3_f("failure partial=%d next methods=\"%s\"", 458 partial, methods); 459 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 460 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 461 (r = sshpkt_put_u8(ssh, partial)) != 0 || 462 (r = sshpkt_send(ssh)) != 0 || 463 (r = ssh_packet_write_wait(ssh)) != 0) 464 fatal_fr(r, "send failure packet"); 465 free(methods); 466 } 467 } 468 469 /* 470 * Checks whether method is allowed by at least one AuthenticationMethods 471 * methods list. Returns 1 if allowed, or no methods lists configured. 472 * 0 otherwise. 473 */ 474 int 475 auth2_method_allowed(Authctxt *authctxt, const char *method, 476 const char *submethod) 477 { 478 u_int i; 479 480 /* 481 * NB. authctxt->num_auth_methods might be zero as a result of 482 * auth2_setup_methods_lists(), so check the configuration. 483 */ 484 if (options.num_auth_methods == 0) 485 return 1; 486 for (i = 0; i < authctxt->num_auth_methods; i++) { 487 if (list_starts_with(authctxt->auth_methods[i], method, 488 submethod) != MATCH_NONE) 489 return 1; 490 } 491 return 0; 492 } 493 494 static char * 495 authmethods_get(Authctxt *authctxt) 496 { 497 struct sshbuf *b; 498 char *list; 499 int i, r; 500 501 if ((b = sshbuf_new()) == NULL) 502 fatal_f("sshbuf_new failed"); 503 for (i = 0; authmethods[i] != NULL; i++) { 504 if (strcmp(authmethods[i]->cfg->name, "none") == 0) 505 continue; 506 if (authmethods[i]->cfg->enabled == NULL || 507 *(authmethods[i]->cfg->enabled) == 0) 508 continue; 509 if (!auth2_method_allowed(authctxt, authmethods[i]->cfg->name, 510 NULL)) 511 continue; 512 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 513 authmethods[i]->cfg->name)) != 0) 514 fatal_fr(r, "buffer error"); 515 } 516 if ((list = sshbuf_dup_string(b)) == NULL) 517 fatal_f("sshbuf_dup_string failed"); 518 sshbuf_free(b); 519 return list; 520 } 521 522 static Authmethod * 523 authmethod_byname(const char *name) 524 { 525 int i; 526 527 if (name == NULL) 528 fatal_f("NULL authentication method name"); 529 for (i = 0; authmethods[i] != NULL; i++) { 530 if (strcmp(name, authmethods[i]->cfg->name) == 0 || 531 (authmethods[i]->cfg->synonym != NULL && 532 strcmp(name, authmethods[i]->cfg->synonym) == 0)) 533 return authmethods[i]; 534 } 535 debug_f("unrecognized authentication method name: %s", name); 536 return NULL; 537 } 538 539 static Authmethod * 540 authmethod_lookup(Authctxt *authctxt, const char *name) 541 { 542 Authmethod *method; 543 544 if ((method = authmethod_byname(name)) == NULL) 545 return NULL; 546 547 if (method->cfg->enabled == NULL || *(method->cfg->enabled) == 0) { 548 debug3_f("method %s not enabled", name); 549 return NULL; 550 } 551 if (!auth2_method_allowed(authctxt, method->cfg->name, NULL)) { 552 debug3_f("method %s not allowed " 553 "by AuthenticationMethods", name); 554 return NULL; 555 } 556 return method; 557 } 558 559 /* 560 * Prune the AuthenticationMethods supplied in the configuration, removing 561 * any methods lists that include disabled methods. Note that this might 562 * leave authctxt->num_auth_methods == 0, even when multiple required auth 563 * has been requested. For this reason, all tests for whether multiple is 564 * enabled should consult options.num_auth_methods directly. 565 */ 566 int 567 auth2_setup_methods_lists(Authctxt *authctxt) 568 { 569 u_int i; 570 571 /* First, normalise away the "any" pseudo-method */ 572 if (options.num_auth_methods == 1 && 573 strcmp(options.auth_methods[0], "any") == 0) { 574 free(options.auth_methods[0]); 575 options.auth_methods[0] = NULL; 576 options.num_auth_methods = 0; 577 } 578 579 if (options.num_auth_methods == 0) 580 return 0; 581 debug3_f("checking methods"); 582 authctxt->auth_methods = xcalloc(options.num_auth_methods, 583 sizeof(*authctxt->auth_methods)); 584 authctxt->num_auth_methods = 0; 585 for (i = 0; i < options.num_auth_methods; i++) { 586 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 587 logit("Authentication methods list \"%s\" contains " 588 "disabled method, skipping", 589 options.auth_methods[i]); 590 continue; 591 } 592 debug("authentication methods list %d: %s", 593 authctxt->num_auth_methods, options.auth_methods[i]); 594 authctxt->auth_methods[authctxt->num_auth_methods++] = 595 xstrdup(options.auth_methods[i]); 596 } 597 if (authctxt->num_auth_methods == 0) { 598 error("No AuthenticationMethods left after eliminating " 599 "disabled methods"); 600 return -1; 601 } 602 return 0; 603 } 604 605 static int 606 list_starts_with(const char *methods, const char *method, 607 const char *submethod) 608 { 609 size_t l = strlen(method); 610 int match; 611 const char *p; 612 613 if (strncmp(methods, method, l) != 0) 614 return MATCH_NONE; 615 p = methods + l; 616 match = MATCH_METHOD; 617 if (*p == ':') { 618 if (!submethod) 619 return MATCH_PARTIAL; 620 l = strlen(submethod); 621 p += 1; 622 if (strncmp(submethod, p, l)) 623 return MATCH_NONE; 624 p += l; 625 match = MATCH_BOTH; 626 } 627 if (*p != ',' && *p != '\0') 628 return MATCH_NONE; 629 return match; 630 } 631 632 /* 633 * Remove method from the start of a comma-separated list of methods. 634 * Returns 0 if the list of methods did not start with that method or 1 635 * if it did. 636 */ 637 static int 638 remove_method(char **methods, const char *method, const char *submethod) 639 { 640 char *omethods = *methods, *p; 641 size_t l = strlen(method); 642 int match; 643 644 match = list_starts_with(omethods, method, submethod); 645 if (match != MATCH_METHOD && match != MATCH_BOTH) 646 return 0; 647 p = omethods + l; 648 if (submethod && match == MATCH_BOTH) 649 p += 1 + strlen(submethod); /* include colon */ 650 if (*p == ',') 651 p++; 652 *methods = xstrdup(p); 653 free(omethods); 654 return 1; 655 } 656 657 /* 658 * Called after successful authentication. Will remove the successful method 659 * from the start of each list in which it occurs. If it was the last method 660 * in any list, then authentication is deemed successful. 661 * Returns 1 if the method completed any authentication list or 0 otherwise. 662 */ 663 int 664 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 665 const char *submethod) 666 { 667 u_int i, found = 0; 668 669 debug3_f("updating methods list after \"%s\"", method); 670 for (i = 0; i < authctxt->num_auth_methods; i++) { 671 if (!remove_method(&(authctxt->auth_methods[i]), method, 672 submethod)) 673 continue; 674 found = 1; 675 if (*authctxt->auth_methods[i] == '\0') { 676 debug2("authentication methods list %d complete", i); 677 return 1; 678 } 679 debug3("authentication methods list %d remaining: \"%s\"", 680 i, authctxt->auth_methods[i]); 681 } 682 /* This should not happen, but would be bad if it did */ 683 if (!found) 684 fatal_f("method not in AuthenticationMethods"); 685 return 0; 686 } 687 688 /* Reset method-specific information */ 689 void auth2_authctxt_reset_info(Authctxt *authctxt) 690 { 691 sshkey_free(authctxt->auth_method_key); 692 free(authctxt->auth_method_info); 693 authctxt->auth_method_key = NULL; 694 authctxt->auth_method_info = NULL; 695 } 696 697 /* Record auth method-specific information for logs */ 698 void 699 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 700 { 701 va_list ap; 702 int i; 703 704 free(authctxt->auth_method_info); 705 authctxt->auth_method_info = NULL; 706 707 va_start(ap, fmt); 708 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 709 va_end(ap); 710 711 if (i == -1) 712 fatal_f("vasprintf failed"); 713 } 714 715 /* 716 * Records a public key used in authentication. This is used for logging 717 * and to ensure that the same key is not subsequently accepted again for 718 * multiple authentication. 719 */ 720 void 721 auth2_record_key(Authctxt *authctxt, int authenticated, 722 const struct sshkey *key) 723 { 724 struct sshkey **tmp, *dup; 725 int r; 726 727 if ((r = sshkey_from_private(key, &dup)) != 0) 728 fatal_fr(r, "copy key"); 729 sshkey_free(authctxt->auth_method_key); 730 authctxt->auth_method_key = dup; 731 732 if (!authenticated) 733 return; 734 735 /* If authenticated, make sure we don't accept this key again */ 736 if ((r = sshkey_from_private(key, &dup)) != 0) 737 fatal_fr(r, "copy key"); 738 if (authctxt->nprev_keys >= INT_MAX || 739 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 740 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 741 fatal_f("reallocarray failed"); 742 authctxt->prev_keys = tmp; 743 authctxt->prev_keys[authctxt->nprev_keys] = dup; 744 authctxt->nprev_keys++; 745 746 } 747 748 /* Checks whether a key has already been previously used for authentication */ 749 int 750 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 751 { 752 u_int i; 753 char *fp; 754 755 for (i = 0; i < authctxt->nprev_keys; i++) { 756 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 757 fp = sshkey_fingerprint(authctxt->prev_keys[i], 758 options.fingerprint_hash, SSH_FP_DEFAULT); 759 debug3_f("key already used: %s %s", 760 sshkey_type(authctxt->prev_keys[i]), 761 fp == NULL ? "UNKNOWN" : fp); 762 free(fp); 763 return 1; 764 } 765 } 766 return 0; 767 } 768 769 /* 770 * Updates authctxt->session_info with details of authentication. Should be 771 * whenever an authentication method succeeds. 772 */ 773 void 774 auth2_update_session_info(Authctxt *authctxt, const char *method, 775 const char *submethod) 776 { 777 int r; 778 779 if (authctxt->session_info == NULL) { 780 if ((authctxt->session_info = sshbuf_new()) == NULL) 781 fatal_f("sshbuf_new"); 782 } 783 784 /* Append method[/submethod] */ 785 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 786 method, submethod == NULL ? "" : "/", 787 submethod == NULL ? "" : submethod)) != 0) 788 fatal_fr(r, "append method"); 789 790 /* Append key if present */ 791 if (authctxt->auth_method_key != NULL) { 792 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 793 (r = sshkey_format_text(authctxt->auth_method_key, 794 authctxt->session_info)) != 0) 795 fatal_fr(r, "append key"); 796 } 797 798 if (authctxt->auth_method_info != NULL) { 799 /* Ensure no ambiguity here */ 800 if (strchr(authctxt->auth_method_info, '\n') != NULL) 801 fatal_f("auth_method_info contains \\n"); 802 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 803 (r = sshbuf_putf(authctxt->session_info, "%s", 804 authctxt->auth_method_info)) != 0) { 805 fatal_fr(r, "append method info"); 806 } 807 } 808 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 809 fatal_fr(r, "append"); 810 } 811 812