1 /* $NetBSD: auth2.c,v 1.32 2024/10/09 01:49:20 rin Exp $ */ 2 /* $OpenBSD: auth2.c,v 1.169 2024/05/17 00:30:23 djm Exp $ */ 3 4 /* 5 * Copyright (c) 2000 Markus Friedl. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include "includes.h" 29 __RCSID("$NetBSD: auth2.c,v 1.32 2024/10/09 01:49:20 rin Exp $"); 30 31 #include <sys/types.h> 32 #include <sys/stat.h> 33 #include <sys/uio.h> 34 35 #include <fcntl.h> 36 #include <limits.h> 37 #include <pwd.h> 38 #include <stdarg.h> 39 #include <string.h> 40 #include <unistd.h> 41 #include <time.h> 42 43 #include "stdlib.h" 44 #include "atomicio.h" 45 #include "xmalloc.h" 46 #include "ssh2.h" 47 #include "packet.h" 48 #include "log.h" 49 #include "sshbuf.h" 50 #include "misc.h" 51 #include "servconf.h" 52 #include "sshkey.h" 53 #include "hostfile.h" 54 #include "auth.h" 55 #include "dispatch.h" 56 #include "pathnames.h" 57 #include "canohost.h" 58 #include "pfilter.h" 59 60 #ifdef GSSAPI 61 #include "ssh-gss.h" 62 #endif 63 64 #include "monitor_wrap.h" 65 #include "ssherr.h" 66 #include "digest.h" 67 #include "kex.h" 68 69 /* import */ 70 extern ServerOptions options; 71 extern struct sshbuf *loginmsg; 72 73 /* methods */ 74 75 extern Authmethod method_none; 76 extern Authmethod method_pubkey; 77 extern Authmethod method_passwd; 78 extern Authmethod method_kbdint; 79 extern Authmethod method_hostbased; 80 #ifdef KRB5 81 extern Authmethod method_kerberos; 82 #endif 83 #ifdef GSSAPI 84 extern Authmethod method_gssapi; 85 #endif 86 87 static int log_flag = 0; 88 89 Authmethod *authmethods[] = { 90 &method_none, 91 &method_pubkey, 92 #ifdef GSSAPI 93 &method_gssapi, 94 #endif 95 &method_passwd, 96 &method_kbdint, 97 &method_hostbased, 98 #ifdef KRB5 99 &method_kerberos, 100 #endif 101 NULL 102 }; 103 104 /* protocol */ 105 106 static int input_service_request(int, u_int32_t, struct ssh *); 107 static int input_userauth_request(int, u_int32_t, struct ssh *); 108 109 /* helper */ 110 static Authmethod *authmethod_byname(const char *); 111 static Authmethod *authmethod_lookup(Authctxt *, const char *); 112 static char *authmethods_get(Authctxt *authctxt); 113 114 #define MATCH_NONE 0 /* method or submethod mismatch */ 115 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 116 #define MATCH_BOTH 2 /* method and submethod match */ 117 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 118 static int list_starts_with(const char *, const char *, const char *); 119 120 char * 121 auth2_read_banner(void) 122 { 123 struct stat st; 124 char *banner = NULL; 125 size_t len, n; 126 int fd; 127 128 if ((fd = open(options.banner, O_RDONLY)) == -1) 129 return (NULL); 130 if (fstat(fd, &st) == -1) { 131 close(fd); 132 return (NULL); 133 } 134 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 135 close(fd); 136 return (NULL); 137 } 138 139 len = (size_t)st.st_size; /* truncate */ 140 banner = xmalloc(len + 1); 141 n = atomicio(read, fd, banner, len); 142 close(fd); 143 144 if (n != len) { 145 free(banner); 146 return (NULL); 147 } 148 banner[n] = '\0'; 149 150 return (banner); 151 } 152 153 static void 154 userauth_send_banner(struct ssh *ssh, const char *msg) 155 { 156 int r; 157 158 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 || 159 (r = sshpkt_put_cstring(ssh, msg)) != 0 || 160 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */ 161 (r = sshpkt_send(ssh)) != 0) 162 fatal_fr(r, "send packet"); 163 debug("%s: sent", __func__); 164 } 165 166 static void 167 userauth_banner(struct ssh *ssh) 168 { 169 char *banner = NULL; 170 171 if (options.banner == NULL) 172 return; 173 174 if ((banner = mm_auth2_read_banner()) == NULL) 175 goto done; 176 userauth_send_banner(ssh, banner); 177 178 done: 179 free(banner); 180 } 181 182 /* 183 * loop until authctxt->success == TRUE 184 */ 185 void 186 do_authentication2(struct ssh *ssh) 187 { 188 Authctxt *authctxt = ssh->authctxt; 189 190 ssh_dispatch_init(ssh, &dispatch_protocol_error); 191 if (ssh->kex->ext_info_c) 192 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_input_ext_info); 193 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); 194 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); 195 ssh->authctxt = NULL; 196 } 197 198 static int 199 input_service_request(int type, u_int32_t seq, struct ssh *ssh) 200 { 201 Authctxt *authctxt = ssh->authctxt; 202 char *service = NULL; 203 int r, acceptit = 0; 204 205 if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 206 (r = sshpkt_get_end(ssh)) != 0) 207 goto out; 208 209 if (authctxt == NULL) 210 fatal("input_service_request: no authctxt"); 211 212 if (strcmp(service, "ssh-userauth") == 0) { 213 if (!authctxt->success) { 214 acceptit = 1; 215 /* now we can handle user-auth requests */ 216 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 217 &input_userauth_request); 218 } 219 } 220 /* XXX all other service requests are denied */ 221 222 if (acceptit) { 223 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 || 224 (r = sshpkt_put_cstring(ssh, service)) != 0 || 225 (r = sshpkt_send(ssh)) != 0 || 226 (r = ssh_packet_write_wait(ssh)) < 0) 227 goto out; 228 } else { 229 debug("bad service request %s", service); 230 ssh_packet_disconnect(ssh, "bad service request %s", service); 231 } 232 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &dispatch_protocol_error); 233 r = 0; 234 out: 235 free(service); 236 return r; 237 } 238 239 #define MIN_FAIL_DELAY_SECONDS 0.005 240 #define MAX_FAIL_DELAY_SECONDS 5.0 241 static double 242 user_specific_delay(const char *user) 243 { 244 char b[512]; 245 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 246 u_char *hash = xmalloc(len); 247 double delay; 248 249 (void)snprintf(b, sizeof b, "%llu%s", 250 (unsigned long long)options.timing_secret, user); 251 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 252 fatal_f("ssh_digest_memory"); 253 /* 0-4.2 ms of delay */ 254 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 255 freezero(hash, len); 256 debug3_f("user specific delay %0.3lfms", delay/1000); 257 return MIN_FAIL_DELAY_SECONDS + delay; 258 } 259 260 static void 261 ensure_minimum_time_since(double start, double seconds) 262 { 263 struct timespec ts; 264 double elapsed = monotime_double() - start, req = seconds, remain; 265 266 if (elapsed > MAX_FAIL_DELAY_SECONDS) { 267 debug3_f("elapsed %0.3lfms exceeded the max delay " 268 "requested %0.3lfms)", elapsed*1000, req*1000); 269 return; 270 } 271 272 /* if we've already passed the requested time, scale up */ 273 while ((remain = seconds - elapsed) < 0.0) 274 seconds *= 2; 275 276 ts.tv_sec = remain; 277 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; 278 debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 279 elapsed*1000, remain*1000, req*1000); 280 nanosleep(&ts, NULL); 281 } 282 283 static int 284 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 285 { 286 Authctxt *authctxt = ssh->authctxt; 287 Authmethod *m = NULL; 288 char *user = NULL, *service = NULL, *method = NULL, *style = NULL; 289 int r, authenticated = 0; 290 double tstart = monotime_double(); 291 292 if (authctxt == NULL) 293 fatal("input_userauth_request: no authctxt"); 294 295 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || 296 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 297 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) 298 goto out; 299 debug("userauth-request for user %s service %s method %s", user, service, method); 300 if (!log_flag) { 301 logit("SSH: Server;Ltype: Authname;Remote: %s-%d;Name: %s", 302 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), user); 303 log_flag = 1; 304 } 305 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 306 307 if ((style = strchr(user, ':')) != NULL) 308 *style++ = 0; 309 310 if (authctxt->attempt >= 1024) 311 auth_maxtries_exceeded(ssh); 312 if (authctxt->attempt++ == 0) { 313 /* setup auth context */ 314 authctxt->pw = mm_getpwnamallow(ssh, user); 315 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 316 authctxt->valid = 1; 317 debug2_f("setting up authctxt for %s", user); 318 } else { 319 authctxt->valid = 0; 320 /* Invalid user, fake password information */ 321 authctxt->pw = fakepw(); 322 } 323 #ifdef USE_PAM 324 if (options.use_pam) 325 mm_start_pam(ssh); 326 #endif 327 ssh_packet_set_log_preamble(ssh, "%suser %s", 328 authctxt->valid ? "authenticating " : "invalid ", user); 329 setproctitle("%s [net]", authctxt->valid ? user : "unknown"); 330 authctxt->user = xstrdup(user); 331 authctxt->service = xstrdup(service); 332 authctxt->style = style ? xstrdup(style) : NULL; 333 mm_inform_authserv(service, style); 334 userauth_banner(ssh); 335 if ((r = kex_server_update_ext_info(ssh)) != 0) 336 fatal_fr(r, "kex_server_update_ext_info failed"); 337 if (auth2_setup_methods_lists(authctxt) != 0) 338 ssh_packet_disconnect(ssh, 339 "no authentication methods enabled"); 340 } else if (strcmp(user, authctxt->user) != 0 || 341 strcmp(service, authctxt->service) != 0) { 342 ssh_packet_disconnect(ssh, "Change of username or service " 343 "not allowed: (%s,%s) -> (%s,%s)", 344 authctxt->user, authctxt->service, user, service); 345 } 346 /* reset state */ 347 auth2_challenge_stop(ssh); 348 349 #ifdef GSSAPI 350 /* XXX move to auth2_gssapi_stop() */ 351 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 352 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 353 #endif 354 355 auth2_authctxt_reset_info(authctxt); 356 authctxt->postponed = 0; 357 authctxt->server_caused_failure = 0; 358 359 /* try to authenticate user */ 360 m = authmethod_lookup(authctxt, method); 361 if (m != NULL && authctxt->failures < options.max_authtries) { 362 debug2("input_userauth_request: try method %s", method); 363 authenticated = m->userauth(ssh, method); 364 } 365 if (!authctxt->authenticated && strcmp(method, "none") != 0) 366 ensure_minimum_time_since(tstart, 367 user_specific_delay(authctxt->user)); 368 userauth_finish(ssh, authenticated, method, NULL); 369 r = 0; 370 out: 371 free(service); 372 free(user); 373 free(method); 374 return r; 375 } 376 377 void 378 userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method, 379 const char *submethod) 380 { 381 Authctxt *authctxt = ssh->authctxt; 382 Authmethod *m = NULL; 383 const char *method = packet_method; 384 char *methods; 385 int r, partial = 0; 386 387 if (authenticated) { 388 if (!authctxt->valid) { 389 fatal("INTERNAL ERROR: authenticated invalid user %s", 390 authctxt->user); 391 } 392 if (authctxt->postponed) 393 fatal("INTERNAL ERROR: authenticated and postponed"); 394 /* prefer primary authmethod name to possible synonym */ 395 if ((m = authmethod_byname(method)) == NULL) 396 fatal("INTERNAL ERROR: bad method %s", method); 397 method = m->cfg->name; 398 } 399 400 /* Special handling for root */ 401 if (authenticated && authctxt->pw->pw_uid == 0 && 402 !auth_root_allowed(ssh, method)) { 403 authenticated = 0; 404 #ifdef SSH_AUDIT_EVENTS 405 PRIVSEP(audit_event(SSH_LOGIN_ROOT_DENIED)); 406 #endif 407 } 408 409 #ifdef USE_PAM 410 if (options.use_pam && authenticated) { 411 int success = mm_do_pam_account(); 412 413 /* if PAM returned a message, send it to the user */ 414 if (sshbuf_len(loginmsg) > 0) { 415 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0) 416 fatal("%s: buffer error: %s", 417 __func__, ssh_err(r)); 418 userauth_send_banner(ssh, 419 (const char *)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 && options.num_auth_methods != 0) { 433 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 434 authenticated = 0; 435 partial = 1; 436 } 437 } 438 439 /* Log before sending the reply */ 440 auth_log(ssh, authenticated, partial, method, submethod); 441 442 /* Update information exposed to session */ 443 if (authenticated || partial) 444 auth2_update_session_info(authctxt, method, submethod); 445 446 if (authctxt->postponed) 447 return; 448 449 if (authenticated == 1) { 450 /* turn off userauth */ 451 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 452 &dispatch_protocol_ignore); 453 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 454 (r = sshpkt_send(ssh)) != 0 || 455 (r = ssh_packet_write_wait(ssh)) < 0) 456 fatal_fr(r, "send success packet"); 457 /* now we can break out */ 458 authctxt->success = 1; 459 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 460 } else { 461 /* Allow initial try of "none" auth without failure penalty */ 462 if (!partial && !authctxt->server_caused_failure && 463 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) 464 authctxt->failures++; 465 if (authctxt->failures >= options.max_authtries) 466 auth_maxtries_exceeded(ssh); 467 methods = authmethods_get(authctxt); 468 debug3_f("failure partial=%d next methods=\"%s\"", 469 partial, methods); 470 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 471 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 472 (r = sshpkt_put_u8(ssh, partial)) != 0 || 473 (r = sshpkt_send(ssh)) != 0 || 474 (r = ssh_packet_write_wait(ssh)) < 0) 475 fatal_fr(r, "send failure packet"); 476 free(methods); 477 } 478 } 479 480 /* 481 * Checks whether method is allowed by at least one AuthenticationMethods 482 * methods list. Returns 1 if allowed, or no methods lists configured. 483 * 0 otherwise. 484 */ 485 int 486 auth2_method_allowed(Authctxt *authctxt, const char *method, 487 const char *submethod) 488 { 489 u_int i; 490 491 /* 492 * NB. authctxt->num_auth_methods might be zero as a result of 493 * auth2_setup_methods_lists(), so check the configuration. 494 */ 495 if (options.num_auth_methods == 0) 496 return 1; 497 for (i = 0; i < authctxt->num_auth_methods; i++) { 498 if (list_starts_with(authctxt->auth_methods[i], method, 499 submethod) != MATCH_NONE) 500 return 1; 501 } 502 return 0; 503 } 504 505 static char * 506 authmethods_get(Authctxt *authctxt) 507 { 508 struct sshbuf *b; 509 char *list; 510 int i, r; 511 512 if ((b = sshbuf_new()) == NULL) 513 fatal_f("sshbuf_new failed"); 514 for (i = 0; authmethods[i] != NULL; i++) { 515 if (strcmp(authmethods[i]->cfg->name, "none") == 0) 516 continue; 517 if (authmethods[i]->cfg->enabled == NULL || 518 *(authmethods[i]->cfg->enabled) == 0) 519 continue; 520 if (!auth2_method_allowed(authctxt, authmethods[i]->cfg->name, 521 NULL)) 522 continue; 523 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 524 authmethods[i]->cfg->name)) != 0) 525 fatal_fr(r, "buffer error"); 526 } 527 if ((list = sshbuf_dup_string(b)) == NULL) 528 fatal_f("sshbuf_dup_string failed"); 529 sshbuf_free(b); 530 return list; 531 } 532 533 static Authmethod * 534 authmethod_byname(const char *name) 535 { 536 int i; 537 538 if (name == NULL) 539 fatal_f("NULL authentication method name"); 540 for (i = 0; authmethods[i] != NULL; i++) { 541 if (strcmp(name, authmethods[i]->cfg->name) == 0 || 542 (authmethods[i]->cfg->synonym != NULL && 543 strcmp(name, authmethods[i]->cfg->synonym) == 0)) 544 return authmethods[i]; 545 } 546 debug_f("unrecognized authentication method name: %s", name); 547 return NULL; 548 } 549 550 static Authmethod * 551 authmethod_lookup(Authctxt *authctxt, const char *name) 552 { 553 Authmethod *method; 554 555 if ((method = authmethod_byname(name)) == NULL) 556 return NULL; 557 558 if (method->cfg->enabled == NULL || *(method->cfg->enabled) == 0) { 559 debug3_f("method %s not enabled", name); 560 return NULL; 561 } 562 if (!auth2_method_allowed(authctxt, method->cfg->name, NULL)) { 563 debug3_f("method %s not allowed " 564 "by AuthenticationMethods", name); 565 return NULL; 566 } 567 return method; 568 } 569 570 /* 571 * Prune the AuthenticationMethods supplied in the configuration, removing 572 * any methods lists that include disabled methods. Note that this might 573 * leave authctxt->num_auth_methods == 0, even when multiple required auth 574 * has been requested. For this reason, all tests for whether multiple is 575 * enabled should consult options.num_auth_methods directly. 576 */ 577 int 578 auth2_setup_methods_lists(Authctxt *authctxt) 579 { 580 u_int i; 581 582 /* First, normalise away the "any" pseudo-method */ 583 if (options.num_auth_methods == 1 && 584 strcmp(options.auth_methods[0], "any") == 0) { 585 free(options.auth_methods[0]); 586 options.auth_methods[0] = NULL; 587 options.num_auth_methods = 0; 588 } 589 590 if (options.num_auth_methods == 0) 591 return 0; 592 debug3_f("checking methods"); 593 authctxt->auth_methods = xcalloc(options.num_auth_methods, 594 sizeof(*authctxt->auth_methods)); 595 authctxt->num_auth_methods = 0; 596 for (i = 0; i < options.num_auth_methods; i++) { 597 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 598 logit("Authentication methods list \"%s\" contains " 599 "disabled method, skipping", 600 options.auth_methods[i]); 601 continue; 602 } 603 debug("authentication methods list %d: %s", 604 authctxt->num_auth_methods, options.auth_methods[i]); 605 authctxt->auth_methods[authctxt->num_auth_methods++] = 606 xstrdup(options.auth_methods[i]); 607 } 608 if (authctxt->num_auth_methods == 0) { 609 error("No AuthenticationMethods left after eliminating " 610 "disabled methods"); 611 return -1; 612 } 613 return 0; 614 } 615 616 static int 617 list_starts_with(const char *methods, const char *method, 618 const char *submethod) 619 { 620 size_t l = strlen(method); 621 int match; 622 const char *p; 623 624 if (strncmp(methods, method, l) != 0) 625 return MATCH_NONE; 626 p = methods + l; 627 match = MATCH_METHOD; 628 if (*p == ':') { 629 if (!submethod) 630 return MATCH_PARTIAL; 631 l = strlen(submethod); 632 p += 1; 633 if (strncmp(submethod, p, l)) 634 return MATCH_NONE; 635 p += l; 636 match = MATCH_BOTH; 637 } 638 if (*p != ',' && *p != '\0') 639 return MATCH_NONE; 640 return match; 641 } 642 643 /* 644 * Remove method from the start of a comma-separated list of methods. 645 * Returns 0 if the list of methods did not start with that method or 1 646 * if it did. 647 */ 648 static int 649 remove_method(char **methods, const char *method, const char *submethod) 650 { 651 char *omethods = *methods, *p; 652 size_t l = strlen(method); 653 int match; 654 655 match = list_starts_with(omethods, method, submethod); 656 if (match != MATCH_METHOD && match != MATCH_BOTH) 657 return 0; 658 p = omethods + l; 659 if (submethod && match == MATCH_BOTH) 660 p += 1 + strlen(submethod); /* include colon */ 661 if (*p == ',') 662 p++; 663 *methods = xstrdup(p); 664 free(omethods); 665 return 1; 666 } 667 668 /* 669 * Called after successful authentication. Will remove the successful method 670 * from the start of each list in which it occurs. If it was the last method 671 * in any list, then authentication is deemed successful. 672 * Returns 1 if the method completed any authentication list or 0 otherwise. 673 */ 674 int 675 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 676 const char *submethod) 677 { 678 u_int i, found = 0; 679 680 debug3_f("updating methods list after \"%s\"", method); 681 for (i = 0; i < authctxt->num_auth_methods; i++) { 682 if (!remove_method(&(authctxt->auth_methods[i]), method, 683 submethod)) 684 continue; 685 found = 1; 686 if (*authctxt->auth_methods[i] == '\0') { 687 debug2("authentication methods list %d complete", i); 688 return 1; 689 } 690 debug3("authentication methods list %d remaining: \"%s\"", 691 i, authctxt->auth_methods[i]); 692 } 693 /* This should not happen, but would be bad if it did */ 694 if (!found) 695 fatal_f("method not in AuthenticationMethods"); 696 return 0; 697 } 698 699 /* Reset method-specific information */ 700 void auth2_authctxt_reset_info(Authctxt *authctxt) 701 { 702 sshkey_free(authctxt->auth_method_key); 703 free(authctxt->auth_method_info); 704 authctxt->auth_method_key = NULL; 705 authctxt->auth_method_info = NULL; 706 } 707 708 /* Record auth method-specific information for logs */ 709 void 710 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 711 { 712 va_list ap; 713 int i; 714 715 free(authctxt->auth_method_info); 716 authctxt->auth_method_info = NULL; 717 718 va_start(ap, fmt); 719 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 720 va_end(ap); 721 722 if (i == -1) 723 fatal_f("vasprintf failed"); 724 } 725 726 /* 727 * Records a public key used in authentication. This is used for logging 728 * and to ensure that the same key is not subsequently accepted again for 729 * multiple authentication. 730 */ 731 void 732 auth2_record_key(Authctxt *authctxt, int authenticated, 733 const struct sshkey *key) 734 { 735 struct sshkey **tmp, *dup; 736 int r; 737 738 if ((r = sshkey_from_private(key, &dup)) != 0) 739 fatal_fr(r, "copy key"); 740 sshkey_free(authctxt->auth_method_key); 741 authctxt->auth_method_key = dup; 742 743 if (!authenticated) 744 return; 745 746 /* If authenticated, make sure we don't accept this key again */ 747 if ((r = sshkey_from_private(key, &dup)) != 0) 748 fatal_fr(r, "copy key"); 749 if (authctxt->nprev_keys >= INT_MAX || 750 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 751 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 752 fatal_f("reallocarray failed"); 753 authctxt->prev_keys = tmp; 754 authctxt->prev_keys[authctxt->nprev_keys] = dup; 755 authctxt->nprev_keys++; 756 757 } 758 759 /* Checks whether a key has already been previously used for authentication */ 760 int 761 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 762 { 763 u_int i; 764 char *fp; 765 766 for (i = 0; i < authctxt->nprev_keys; i++) { 767 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 768 fp = sshkey_fingerprint(authctxt->prev_keys[i], 769 options.fingerprint_hash, SSH_FP_DEFAULT); 770 debug3_f("key already used: %s %s", 771 sshkey_type(authctxt->prev_keys[i]), 772 fp == NULL ? "UNKNOWN" : fp); 773 free(fp); 774 return 1; 775 } 776 } 777 return 0; 778 } 779 780 /* 781 * Updates authctxt->session_info with details of authentication. Should be 782 * whenever an authentication method succeeds. 783 */ 784 void 785 auth2_update_session_info(Authctxt *authctxt, const char *method, 786 const char *submethod) 787 { 788 int r; 789 790 if (authctxt->session_info == NULL) { 791 if ((authctxt->session_info = sshbuf_new()) == NULL) 792 fatal_f("sshbuf_new"); 793 } 794 795 /* Append method[/submethod] */ 796 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 797 method, submethod == NULL ? "" : "/", 798 submethod == NULL ? "" : submethod)) != 0) 799 fatal_fr(r, "append method"); 800 801 /* Append key if present */ 802 if (authctxt->auth_method_key != NULL) { 803 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 804 (r = sshkey_format_text(authctxt->auth_method_key, 805 authctxt->session_info)) != 0) 806 fatal_fr(r, "append key"); 807 } 808 809 if (authctxt->auth_method_info != NULL) { 810 /* Ensure no ambiguity here */ 811 if (strchr(authctxt->auth_method_info, '\n') != NULL) 812 fatal_f("auth_method_info contains \\n"); 813 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 814 (r = sshbuf_putf(authctxt->session_info, "%s", 815 authctxt->auth_method_info)) != 0) { 816 fatal_fr(r, "append method info"); 817 } 818 } 819 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 820 fatal_fr(r, "append"); 821 } 822 823