1 /* $OpenBSD: auth2.c,v 1.174 2026/07/06 07:44:48 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 #ifdef GSSAPI 56 #include "ssh-gss.h" 57 #endif 58 #include "monitor_wrap.h" 59 #include "digest.h" 60 #include "kex.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, uint32_t, struct ssh *); 92 static int input_userauth_request(int, uint32_t, struct ssh *); 93 94 /* helper */ 95 static Authmethod *authmethod_byname(const char *); 96 static Authmethod *authmethod_lookup(Authctxt *, const char *); 97 static char *authmethods_get(Authctxt *authctxt); 98 99 #define MATCH_NONE 0 /* method or submethod mismatch */ 100 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 101 #define MATCH_BOTH 2 /* method and submethod match */ 102 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 103 static int list_starts_with(const char *, const char *, const char *); 104 105 char * 106 auth2_read_banner(void) 107 { 108 struct stat st; 109 char *banner = NULL; 110 size_t len, n; 111 int fd; 112 113 if ((fd = open(options.banner, O_RDONLY)) == -1) 114 return (NULL); 115 if (fstat(fd, &st) == -1) { 116 close(fd); 117 return (NULL); 118 } 119 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 120 close(fd); 121 return (NULL); 122 } 123 124 len = (size_t)st.st_size; /* truncate */ 125 banner = xmalloc(len + 1); 126 n = atomicio(read, fd, banner, len); 127 close(fd); 128 129 if (n != len) { 130 free(banner); 131 return (NULL); 132 } 133 banner[n] = '\0'; 134 135 return (banner); 136 } 137 138 static void 139 userauth_send_banner(struct ssh *ssh, const char *msg) 140 { 141 int r; 142 143 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 || 144 (r = sshpkt_put_cstring(ssh, msg)) != 0 || 145 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */ 146 (r = sshpkt_send(ssh)) != 0) 147 fatal_fr(r, "send packet"); 148 debug_f("sent"); 149 } 150 151 static void 152 userauth_banner(struct ssh *ssh) 153 { 154 char *banner = NULL; 155 156 if (options.banner == NULL) 157 return; 158 159 if ((banner = mm_auth2_read_banner()) == NULL) 160 goto done; 161 userauth_send_banner(ssh, banner); 162 163 done: 164 free(banner); 165 } 166 167 /* 168 * loop until authctxt->success == TRUE 169 */ 170 void 171 do_authentication2(struct ssh *ssh) 172 { 173 Authctxt *authctxt = ssh->authctxt; 174 175 ssh_dispatch_init(ssh, &dispatch_protocol_error); 176 if (ssh->kex->ext_info_c) 177 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_input_ext_info); 178 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); 179 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); 180 ssh->authctxt = NULL; 181 } 182 183 static int 184 input_service_request(int type, uint32_t seq, struct ssh *ssh) 185 { 186 Authctxt *authctxt = ssh->authctxt; 187 char *service = NULL; 188 int r, acceptit = 0; 189 190 if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 191 (r = sshpkt_get_end(ssh)) != 0) 192 goto out; 193 194 if (authctxt == NULL) 195 fatal("input_service_request: no authctxt"); 196 197 if (strcmp(service, "ssh-userauth") == 0) { 198 if (!authctxt->success) { 199 acceptit = 1; 200 /* now we can handle user-auth requests */ 201 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 202 &input_userauth_request); 203 } 204 } 205 /* XXX all other service requests are denied */ 206 207 if (acceptit) { 208 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 || 209 (r = sshpkt_put_cstring(ssh, service)) != 0 || 210 (r = sshpkt_send(ssh)) != 0 || 211 (r = ssh_packet_write_wait(ssh)) != 0) 212 goto out; 213 } else { 214 debug("bad service request %s", service); 215 ssh_packet_disconnect(ssh, "bad service request %s", service); 216 } 217 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &dispatch_protocol_error); 218 r = 0; 219 out: 220 free(service); 221 return r; 222 } 223 224 #define MIN_FAIL_DELAY_SECONDS 0.005 225 #define MAX_FAIL_DELAY_SECONDS 5.0 226 static double 227 user_specific_delay(const char *user) 228 { 229 char b[512]; 230 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 231 u_char *hash = xmalloc(len); 232 double delay; 233 234 (void)snprintf(b, sizeof b, "%llu%s", 235 (unsigned long long)options.timing_secret, user); 236 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 237 fatal_f("ssh_digest_memory"); 238 /* 0-4.2 ms of delay */ 239 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 240 freezero(hash, len); 241 debug3_f("user specific delay %0.3lfms", delay*1000); 242 return MIN_FAIL_DELAY_SECONDS + delay; 243 } 244 245 static void 246 ensure_minimum_time_since(double start, double seconds) 247 { 248 struct timespec ts; 249 double elapsed = monotime_double() - start, req = seconds, remain; 250 251 if (elapsed > MAX_FAIL_DELAY_SECONDS) { 252 debug3_f("elapsed %0.3lfms exceeded the max delay " 253 "requested %0.3lfms)", elapsed*1000, req*1000); 254 return; 255 } 256 257 /* if we've already passed the requested time, scale up */ 258 while ((remain = seconds - elapsed) < 0.0) 259 seconds *= 2; 260 261 ts.tv_sec = remain; 262 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; 263 debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 264 elapsed*1000, remain*1000, req*1000); 265 nanosleep(&ts, NULL); 266 } 267 268 void 269 auth_failure_delay(Authctxt *authctxt, double tstart) 270 { 271 ensure_minimum_time_since(tstart, user_specific_delay(authctxt->user)); 272 } 273 274 static int 275 input_userauth_request(int type, uint32_t seq, struct ssh *ssh) 276 { 277 Authctxt *authctxt = ssh->authctxt; 278 Authmethod *m = NULL; 279 char *user = NULL, *service = NULL, *method = NULL, *style = NULL; 280 int r, authenticated = 0; 281 double tstart = monotime_double(); 282 283 if (authctxt == NULL) 284 fatal("input_userauth_request: no authctxt"); 285 286 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || 287 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 288 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) 289 goto out; 290 debug("userauth-request for user %s service %s method %s", user, service, method); 291 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 292 293 if ((style = strchr(user, ':')) != NULL) 294 *style++ = 0; 295 296 if (authctxt->attempt >= 1024) 297 auth_maxtries_exceeded(ssh); 298 if (authctxt->attempt++ == 0) { 299 /* setup auth context */ 300 authctxt->pw = mm_getpwnamallow(ssh, user); 301 authctxt->user = xstrdup(user); 302 authctxt->service = xstrdup(service); 303 authctxt->style = style ? xstrdup(style) : NULL; 304 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 305 authctxt->valid = 1; 306 debug2_f("setting up authctxt for %s", user); 307 } else { 308 authctxt->valid = 0; 309 /* Invalid user, fake password information */ 310 authctxt->pw = fakepw(); 311 #ifdef SSH_AUDIT_EVENTS 312 mm_audit_event(ssh, SSH_INVALID_USER); 313 #endif 314 } 315 #ifdef USE_PAM 316 if (options.use_pam) 317 mm_start_pam(ssh); 318 #endif 319 ssh_packet_set_log_preamble(ssh, "%suser %s", 320 authctxt->valid ? "authenticating " : "invalid ", user); 321 setproctitle("%s [net]", authctxt->valid ? user : "unknown"); 322 mm_inform_authserv(service, style); 323 userauth_banner(ssh); 324 if ((r = kex_server_update_ext_info(ssh)) != 0) 325 fatal_fr(r, "kex_server_update_ext_info failed"); 326 if (auth2_setup_methods_lists(authctxt) != 0) 327 ssh_packet_disconnect(ssh, 328 "no authentication methods enabled"); 329 } else if (strcmp(user, authctxt->user) != 0 || 330 strcmp(service, authctxt->service) != 0) { 331 ssh_packet_disconnect(ssh, "Change of username or service " 332 "not allowed: (%s,%s) -> (%s,%s)", 333 authctxt->user, authctxt->service, user, service); 334 } 335 /* reset state */ 336 auth2_challenge_stop(ssh); 337 338 #ifdef GSSAPI 339 /* XXX move to auth2_gssapi_stop() */ 340 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 341 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 342 #endif 343 344 auth2_authctxt_reset_info(authctxt); 345 authctxt->postponed = 0; 346 authctxt->server_caused_failure = 0; 347 348 /* try to authenticate user */ 349 m = authmethod_lookup(authctxt, method); 350 if (m != NULL && authctxt->failures < options.max_authtries) { 351 debug2("input_userauth_request: try method %s", method); 352 authenticated = m->userauth(ssh, method); 353 } 354 if (!authctxt->authenticated && strcmp(method, "none") != 0) 355 auth_failure_delay(authctxt, tstart); 356 357 userauth_finish(ssh, authenticated, method, NULL); 358 r = 0; 359 out: 360 free(service); 361 free(user); 362 free(method); 363 return r; 364 } 365 366 void 367 userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method, 368 const char *submethod) 369 { 370 Authctxt *authctxt = ssh->authctxt; 371 Authmethod *m = NULL; 372 const char *method = packet_method; 373 char *methods; 374 int r, partial = 0; 375 376 if (authenticated) { 377 if (!authctxt->valid) { 378 fatal("INTERNAL ERROR: authenticated invalid user %s", 379 authctxt->user); 380 } 381 if (authctxt->postponed) 382 fatal("INTERNAL ERROR: authenticated and postponed"); 383 /* prefer primary authmethod name to possible synonym */ 384 if ((m = authmethod_byname(method)) == NULL) 385 fatal("INTERNAL ERROR: bad method %s", method); 386 method = m->cfg->name; 387 } 388 389 /* Special handling for root */ 390 if (authenticated && authctxt->pw->pw_uid == 0 && 391 !auth_root_allowed(ssh, method)) { 392 authenticated = 0; 393 #ifdef SSH_AUDIT_EVENTS 394 mm_audit_event(ssh, SSH_LOGIN_ROOT_DENIED); 395 #endif 396 } 397 398 if (authenticated && options.num_auth_methods != 0) { 399 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 400 authenticated = 0; 401 partial = 1; 402 } 403 } 404 405 /* Log before sending the reply */ 406 auth_log(ssh, authenticated, partial, method, submethod); 407 408 /* Update information exposed to session */ 409 if (authenticated || partial) 410 auth2_update_session_info(authctxt, method, submethod); 411 412 if (authctxt->postponed) 413 return; 414 415 #ifdef USE_PAM 416 if (options.use_pam && authenticated) { 417 int r, success = mm_do_pam_account(); 418 419 /* If PAM returned a message, send it to the user. */ 420 if (sshbuf_len(loginmsg) > 0) { 421 if ((r = sshbuf_put(loginmsg, "\0", 1)) != 0) 422 fatal("%s: buffer error: %s", 423 __func__, ssh_err(r)); 424 userauth_send_banner(ssh, sshbuf_ptr(loginmsg)); 425 if ((r = ssh_packet_write_wait(ssh)) != 0) { 426 sshpkt_fatal(ssh, r, 427 "%s: send PAM banner", __func__); 428 } 429 } 430 if (!success) { 431 fatal("Access denied for user %s by PAM account " 432 "configuration", authctxt->user); 433 } 434 } 435 #endif 436 437 if (authenticated == 1) { 438 /* turn off userauth */ 439 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 440 &dispatch_protocol_ignore); 441 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 442 (r = sshpkt_send(ssh)) != 0 || 443 (r = ssh_packet_write_wait(ssh)) != 0) 444 fatal_fr(r, "send success packet"); 445 /* now we can break out */ 446 authctxt->success = 1; 447 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 448 } else { 449 /* Allow initial try of "none" auth without failure penalty */ 450 if (!partial && !authctxt->server_caused_failure && 451 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) 452 authctxt->failures++; 453 if (authctxt->failures >= options.max_authtries) { 454 #ifdef SSH_AUDIT_EVENTS 455 mm_audit_event(ssh, SSH_LOGIN_EXCEED_MAXTRIES); 456 #endif 457 auth_maxtries_exceeded(ssh); 458 } 459 methods = authmethods_get(authctxt); 460 debug3_f("failure partial=%d next methods=\"%s\"", 461 partial, methods); 462 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 463 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 464 (r = sshpkt_put_u8(ssh, partial)) != 0 || 465 (r = sshpkt_send(ssh)) != 0 || 466 (r = ssh_packet_write_wait(ssh)) != 0) 467 fatal_fr(r, "send failure packet"); 468 free(methods); 469 } 470 } 471 472 /* 473 * Checks whether method is allowed by at least one AuthenticationMethods 474 * methods list. Returns 1 if allowed, or no methods lists configured. 475 * 0 otherwise. 476 */ 477 int 478 auth2_method_allowed(Authctxt *authctxt, const char *method, 479 const char *submethod) 480 { 481 u_int i; 482 483 /* 484 * NB. authctxt->num_auth_methods might be zero as a result of 485 * auth2_setup_methods_lists(), so check the configuration. 486 */ 487 if (options.num_auth_methods == 0) 488 return 1; 489 for (i = 0; i < authctxt->num_auth_methods; i++) { 490 if (list_starts_with(authctxt->auth_methods[i], method, 491 submethod) != MATCH_NONE) 492 return 1; 493 } 494 return 0; 495 } 496 497 static char * 498 authmethods_get(Authctxt *authctxt) 499 { 500 struct sshbuf *b; 501 char *list; 502 int i, r; 503 504 if ((b = sshbuf_new()) == NULL) 505 fatal_f("sshbuf_new failed"); 506 for (i = 0; authmethods[i] != NULL; i++) { 507 if (strcmp(authmethods[i]->cfg->name, "none") == 0) 508 continue; 509 if (authmethods[i]->cfg->enabled == NULL || 510 *(authmethods[i]->cfg->enabled) == 0) 511 continue; 512 if (!auth2_method_allowed(authctxt, authmethods[i]->cfg->name, 513 NULL)) 514 continue; 515 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 516 authmethods[i]->cfg->name)) != 0) 517 fatal_fr(r, "buffer error"); 518 } 519 if ((list = sshbuf_dup_string(b)) == NULL) 520 fatal_f("sshbuf_dup_string failed"); 521 sshbuf_free(b); 522 return list; 523 } 524 525 static Authmethod * 526 authmethod_byname(const char *name) 527 { 528 int i; 529 530 if (name == NULL) 531 fatal_f("NULL authentication method name"); 532 for (i = 0; authmethods[i] != NULL; i++) { 533 if (strcmp(name, authmethods[i]->cfg->name) == 0 || 534 (authmethods[i]->cfg->synonym != NULL && 535 strcmp(name, authmethods[i]->cfg->synonym) == 0)) 536 return authmethods[i]; 537 } 538 debug_f("unrecognized authentication method name: %s", name); 539 return NULL; 540 } 541 542 static Authmethod * 543 authmethod_lookup(Authctxt *authctxt, const char *name) 544 { 545 Authmethod *method; 546 547 if ((method = authmethod_byname(name)) == NULL) 548 return NULL; 549 550 if (method->cfg->enabled == NULL || *(method->cfg->enabled) == 0) { 551 debug3_f("method %s not enabled", name); 552 return NULL; 553 } 554 if (!auth2_method_allowed(authctxt, method->cfg->name, NULL)) { 555 debug3_f("method %s not allowed " 556 "by AuthenticationMethods", name); 557 return NULL; 558 } 559 return method; 560 } 561 562 /* 563 * Prune the AuthenticationMethods supplied in the configuration, removing 564 * any methods lists that include disabled methods. Note that this might 565 * leave authctxt->num_auth_methods == 0, even when multiple required auth 566 * has been requested. For this reason, all tests for whether multiple is 567 * enabled should consult options.num_auth_methods directly. 568 */ 569 int 570 auth2_setup_methods_lists(Authctxt *authctxt) 571 { 572 u_int i; 573 574 /* First, normalise away the "any" pseudo-method */ 575 if (options.num_auth_methods == 1 && 576 strcmp(options.auth_methods[0], "any") == 0) { 577 free(options.auth_methods[0]); 578 options.auth_methods[0] = NULL; 579 options.num_auth_methods = 0; 580 } 581 582 if (options.num_auth_methods == 0) 583 return 0; 584 debug3_f("checking methods"); 585 authctxt->auth_methods = xcalloc(options.num_auth_methods, 586 sizeof(*authctxt->auth_methods)); 587 authctxt->num_auth_methods = 0; 588 for (i = 0; i < options.num_auth_methods; i++) { 589 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 590 logit("Authentication methods list \"%s\" contains " 591 "disabled method, skipping", 592 options.auth_methods[i]); 593 continue; 594 } 595 debug("authentication methods list %d: %s", 596 authctxt->num_auth_methods, options.auth_methods[i]); 597 authctxt->auth_methods[authctxt->num_auth_methods++] = 598 xstrdup(options.auth_methods[i]); 599 } 600 if (authctxt->num_auth_methods == 0) { 601 error("No AuthenticationMethods left after eliminating " 602 "disabled methods"); 603 return -1; 604 } 605 return 0; 606 } 607 608 static int 609 list_starts_with(const char *methods, const char *method, 610 const char *submethod) 611 { 612 size_t l = strlen(method); 613 int match; 614 const char *p; 615 616 if (strncmp(methods, method, l) != 0) 617 return MATCH_NONE; 618 p = methods + l; 619 match = MATCH_METHOD; 620 if (*p == ':') { 621 if (!submethod) 622 return MATCH_PARTIAL; 623 l = strlen(submethod); 624 p += 1; 625 if (strncmp(submethod, p, l)) 626 return MATCH_NONE; 627 p += l; 628 match = MATCH_BOTH; 629 } 630 if (*p != ',' && *p != '\0') 631 return MATCH_NONE; 632 return match; 633 } 634 635 /* 636 * Remove method from the start of a comma-separated list of methods. 637 * Returns 0 if the list of methods did not start with that method or 1 638 * if it did. 639 */ 640 static int 641 remove_method(char **methods, const char *method, const char *submethod) 642 { 643 char *omethods = *methods, *p; 644 size_t l = strlen(method); 645 int match; 646 647 match = list_starts_with(omethods, method, submethod); 648 if (match != MATCH_METHOD && match != MATCH_BOTH) 649 return 0; 650 p = omethods + l; 651 if (submethod && match == MATCH_BOTH) 652 p += 1 + strlen(submethod); /* include colon */ 653 if (*p == ',') 654 p++; 655 *methods = xstrdup(p); 656 free(omethods); 657 return 1; 658 } 659 660 /* 661 * Called after successful authentication. Will remove the successful method 662 * from the start of each list in which it occurs. If it was the last method 663 * in any list, then authentication is deemed successful. 664 * Returns 1 if the method completed any authentication list or 0 otherwise. 665 */ 666 int 667 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 668 const char *submethod) 669 { 670 u_int i, found = 0; 671 672 debug3_f("updating methods list after \"%s\"", method); 673 for (i = 0; i < authctxt->num_auth_methods; i++) { 674 if (!remove_method(&(authctxt->auth_methods[i]), method, 675 submethod)) 676 continue; 677 found = 1; 678 if (*authctxt->auth_methods[i] == '\0') { 679 debug2("authentication methods list %d complete", i); 680 return 1; 681 } 682 debug3("authentication methods list %d remaining: \"%s\"", 683 i, authctxt->auth_methods[i]); 684 } 685 /* This should not happen, but would be bad if it did */ 686 if (!found) 687 fatal_f("method not in AuthenticationMethods"); 688 return 0; 689 } 690 691 /* Reset method-specific information */ 692 void auth2_authctxt_reset_info(Authctxt *authctxt) 693 { 694 sshkey_free(authctxt->auth_method_key); 695 free(authctxt->auth_method_info); 696 authctxt->auth_method_key = NULL; 697 authctxt->auth_method_info = NULL; 698 } 699 700 /* Record auth method-specific information for logs */ 701 void 702 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 703 { 704 va_list ap; 705 int i; 706 707 free(authctxt->auth_method_info); 708 authctxt->auth_method_info = NULL; 709 710 va_start(ap, fmt); 711 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 712 va_end(ap); 713 714 if (i == -1) 715 fatal_f("vasprintf failed"); 716 } 717 718 /* 719 * Records a public key used in authentication. This is used for logging 720 * and to ensure that the same key is not subsequently accepted again for 721 * multiple authentication. 722 */ 723 void 724 auth2_record_key(Authctxt *authctxt, int authenticated, 725 const struct sshkey *key) 726 { 727 struct sshkey **tmp, *dup; 728 int r; 729 730 if ((r = sshkey_from_private(key, &dup)) != 0) 731 fatal_fr(r, "copy key"); 732 sshkey_free(authctxt->auth_method_key); 733 authctxt->auth_method_key = dup; 734 735 if (!authenticated) 736 return; 737 738 /* If authenticated, make sure we don't accept this key again */ 739 if ((r = sshkey_from_private(key, &dup)) != 0) 740 fatal_fr(r, "copy key"); 741 if (authctxt->nprev_keys >= INT_MAX || 742 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 743 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 744 fatal_f("reallocarray failed"); 745 authctxt->prev_keys = tmp; 746 authctxt->prev_keys[authctxt->nprev_keys] = dup; 747 authctxt->nprev_keys++; 748 749 } 750 751 /* Checks whether a key has already been previously used for authentication */ 752 int 753 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 754 { 755 u_int i; 756 char *fp; 757 758 for (i = 0; i < authctxt->nprev_keys; i++) { 759 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 760 fp = sshkey_fingerprint(authctxt->prev_keys[i], 761 options.fingerprint_hash, SSH_FP_DEFAULT); 762 debug3_f("key already used: %s %s", 763 sshkey_type(authctxt->prev_keys[i]), 764 fp == NULL ? "UNKNOWN" : fp); 765 free(fp); 766 return 1; 767 } 768 } 769 return 0; 770 } 771 772 /* 773 * Updates authctxt->session_info with details of authentication. Should be 774 * whenever an authentication method succeeds. 775 */ 776 void 777 auth2_update_session_info(Authctxt *authctxt, const char *method, 778 const char *submethod) 779 { 780 int r; 781 782 if (authctxt->session_info == NULL) { 783 if ((authctxt->session_info = sshbuf_new()) == NULL) 784 fatal_f("sshbuf_new"); 785 } 786 787 /* Append method[/submethod] */ 788 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 789 method, submethod == NULL ? "" : "/", 790 submethod == NULL ? "" : submethod)) != 0) 791 fatal_fr(r, "append method"); 792 793 /* Append key if present */ 794 if (authctxt->auth_method_key != NULL) { 795 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 796 (r = sshkey_format_text(authctxt->auth_method_key, 797 authctxt->session_info)) != 0) 798 fatal_fr(r, "append key"); 799 } 800 801 if (authctxt->auth_method_info != NULL) { 802 /* Ensure no ambiguity here */ 803 if (strchr(authctxt->auth_method_info, '\n') != NULL) 804 fatal_f("auth_method_info contains \\n"); 805 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 806 (r = sshbuf_putf(authctxt->session_info, "%s", 807 authctxt->auth_method_info)) != 0) { 808 fatal_fr(r, "append method info"); 809 } 810 } 811 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 812 fatal_fr(r, "append"); 813 } 814 815