1 /* $OpenBSD: auth2.c,v 1.164 2022/02/23 11:18:13 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 "compat.h" 48 #include "sshkey.h" 49 #include "hostfile.h" 50 #include "auth.h" 51 #include "dispatch.h" 52 #include "pathnames.h" 53 #ifdef GSSAPI 54 #include "ssh-gss.h" 55 #endif 56 #include "monitor_wrap.h" 57 #include "ssherr.h" 58 #include "digest.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 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); 167 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); 168 ssh->authctxt = NULL; 169 } 170 171 /*ARGSUSED*/ 172 static int 173 input_service_request(int type, u_int32_t seq, struct ssh *ssh) 174 { 175 Authctxt *authctxt = ssh->authctxt; 176 char *service = NULL; 177 int r, acceptit = 0; 178 179 if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 180 (r = sshpkt_get_end(ssh)) != 0) 181 goto out; 182 183 if (authctxt == NULL) 184 fatal("input_service_request: no authctxt"); 185 186 if (strcmp(service, "ssh-userauth") == 0) { 187 if (!authctxt->success) { 188 acceptit = 1; 189 /* now we can handle user-auth requests */ 190 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 191 &input_userauth_request); 192 } 193 } 194 /* XXX all other service requests are denied */ 195 196 if (acceptit) { 197 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 || 198 (r = sshpkt_put_cstring(ssh, service)) != 0 || 199 (r = sshpkt_send(ssh)) != 0 || 200 (r = ssh_packet_write_wait(ssh)) != 0) 201 goto out; 202 } else { 203 debug("bad service request %s", service); 204 ssh_packet_disconnect(ssh, "bad service request %s", service); 205 } 206 r = 0; 207 out: 208 free(service); 209 return r; 210 } 211 212 #define MIN_FAIL_DELAY_SECONDS 0.005 213 static double 214 user_specific_delay(const char *user) 215 { 216 char b[512]; 217 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 218 u_char *hash = xmalloc(len); 219 double delay; 220 221 (void)snprintf(b, sizeof b, "%llu%s", 222 (unsigned long long)options.timing_secret, user); 223 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 224 fatal_f("ssh_digest_memory"); 225 /* 0-4.2 ms of delay */ 226 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 227 freezero(hash, len); 228 debug3_f("user specific delay %0.3lfms", delay/1000); 229 return MIN_FAIL_DELAY_SECONDS + delay; 230 } 231 232 static void 233 ensure_minimum_time_since(double start, double seconds) 234 { 235 struct timespec ts; 236 double elapsed = monotime_double() - start, req = seconds, remain; 237 238 /* if we've already passed the requested time, scale up */ 239 while ((remain = seconds - elapsed) < 0.0) 240 seconds *= 2; 241 242 ts.tv_sec = remain; 243 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; 244 debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 245 elapsed*1000, remain*1000, req*1000); 246 nanosleep(&ts, NULL); 247 } 248 249 /*ARGSUSED*/ 250 static int 251 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 252 { 253 Authctxt *authctxt = ssh->authctxt; 254 Authmethod *m = NULL; 255 char *user = NULL, *service = NULL, *method = NULL, *style = NULL; 256 int r, authenticated = 0; 257 double tstart = monotime_double(); 258 259 if (authctxt == NULL) 260 fatal("input_userauth_request: no authctxt"); 261 262 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || 263 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 264 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) 265 goto out; 266 debug("userauth-request for user %s service %s method %s", user, service, method); 267 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 268 269 if ((style = strchr(user, ':')) != NULL) 270 *style++ = 0; 271 272 if (authctxt->attempt >= 1024) 273 auth_maxtries_exceeded(ssh); 274 if (authctxt->attempt++ == 0) { 275 /* setup auth context */ 276 authctxt->pw = PRIVSEP(getpwnamallow(ssh, user)); 277 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 278 authctxt->valid = 1; 279 debug2_f("setting up authctxt for %s", user); 280 } else { 281 authctxt->valid = 0; 282 /* Invalid user, fake password information */ 283 authctxt->pw = fakepw(); 284 } 285 ssh_packet_set_log_preamble(ssh, "%suser %s", 286 authctxt->valid ? "authenticating " : "invalid ", user); 287 setproctitle("%s%s", authctxt->valid ? user : "unknown", 288 use_privsep ? " [net]" : ""); 289 authctxt->user = xstrdup(user); 290 authctxt->service = xstrdup(service); 291 authctxt->style = style ? xstrdup(style) : NULL; 292 if (use_privsep) 293 mm_inform_authserv(service, style); 294 userauth_banner(ssh); 295 if (auth2_setup_methods_lists(authctxt) != 0) 296 ssh_packet_disconnect(ssh, 297 "no authentication methods enabled"); 298 } else if (strcmp(user, authctxt->user) != 0 || 299 strcmp(service, authctxt->service) != 0) { 300 ssh_packet_disconnect(ssh, "Change of username or service " 301 "not allowed: (%s,%s) -> (%s,%s)", 302 authctxt->user, authctxt->service, user, service); 303 } 304 /* reset state */ 305 auth2_challenge_stop(ssh); 306 307 #ifdef GSSAPI 308 /* XXX move to auth2_gssapi_stop() */ 309 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 310 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 311 #endif 312 313 auth2_authctxt_reset_info(authctxt); 314 authctxt->postponed = 0; 315 authctxt->server_caused_failure = 0; 316 317 /* try to authenticate user */ 318 m = authmethod_lookup(authctxt, method); 319 if (m != NULL && authctxt->failures < options.max_authtries) { 320 debug2("input_userauth_request: try method %s", method); 321 authenticated = m->userauth(ssh, method); 322 } 323 if (!authctxt->authenticated) 324 ensure_minimum_time_since(tstart, 325 user_specific_delay(authctxt->user)); 326 userauth_finish(ssh, authenticated, method, NULL); 327 r = 0; 328 out: 329 free(service); 330 free(user); 331 free(method); 332 return r; 333 } 334 335 void 336 userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method, 337 const char *submethod) 338 { 339 Authctxt *authctxt = ssh->authctxt; 340 Authmethod *m = NULL; 341 const char *method = packet_method; 342 char *methods; 343 int r, partial = 0; 344 345 if (authenticated) { 346 if (!authctxt->valid) { 347 fatal("INTERNAL ERROR: authenticated invalid user %s", 348 authctxt->user); 349 } 350 if (authctxt->postponed) 351 fatal("INTERNAL ERROR: authenticated and postponed"); 352 /* prefer primary authmethod name to possible synonym */ 353 if ((m = authmethod_byname(method)) == NULL) 354 fatal("INTERNAL ERROR: bad method %s", method); 355 method = m->name; 356 } 357 358 /* Special handling for root */ 359 if (authenticated && authctxt->pw->pw_uid == 0 && 360 !auth_root_allowed(ssh, method)) 361 authenticated = 0; 362 363 if (authenticated && options.num_auth_methods != 0) { 364 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 365 authenticated = 0; 366 partial = 1; 367 } 368 } 369 370 /* Log before sending the reply */ 371 auth_log(ssh, authenticated, partial, method, submethod); 372 373 /* Update information exposed to session */ 374 if (authenticated || partial) 375 auth2_update_session_info(authctxt, method, submethod); 376 377 if (authctxt->postponed) 378 return; 379 380 if (authenticated == 1) { 381 /* turn off userauth */ 382 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 383 &dispatch_protocol_ignore); 384 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 385 (r = sshpkt_send(ssh)) != 0 || 386 (r = ssh_packet_write_wait(ssh)) != 0) 387 fatal_fr(r, "send success packet"); 388 /* now we can break out */ 389 authctxt->success = 1; 390 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 391 } else { 392 /* Allow initial try of "none" auth without failure penalty */ 393 if (!partial && !authctxt->server_caused_failure && 394 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) 395 authctxt->failures++; 396 if (authctxt->failures >= options.max_authtries) 397 auth_maxtries_exceeded(ssh); 398 methods = authmethods_get(authctxt); 399 debug3_f("failure partial=%d next methods=\"%s\"", 400 partial, methods); 401 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 402 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 403 (r = sshpkt_put_u8(ssh, partial)) != 0 || 404 (r = sshpkt_send(ssh)) != 0 || 405 (r = ssh_packet_write_wait(ssh)) != 0) 406 fatal_fr(r, "send failure packet"); 407 free(methods); 408 } 409 } 410 411 /* 412 * Checks whether method is allowed by at least one AuthenticationMethods 413 * methods list. Returns 1 if allowed, or no methods lists configured. 414 * 0 otherwise. 415 */ 416 int 417 auth2_method_allowed(Authctxt *authctxt, const char *method, 418 const char *submethod) 419 { 420 u_int i; 421 422 /* 423 * NB. authctxt->num_auth_methods might be zero as a result of 424 * auth2_setup_methods_lists(), so check the configuration. 425 */ 426 if (options.num_auth_methods == 0) 427 return 1; 428 for (i = 0; i < authctxt->num_auth_methods; i++) { 429 if (list_starts_with(authctxt->auth_methods[i], method, 430 submethod) != MATCH_NONE) 431 return 1; 432 } 433 return 0; 434 } 435 436 static char * 437 authmethods_get(Authctxt *authctxt) 438 { 439 struct sshbuf *b; 440 char *list; 441 int i, r; 442 443 if ((b = sshbuf_new()) == NULL) 444 fatal_f("sshbuf_new failed"); 445 for (i = 0; authmethods[i] != NULL; i++) { 446 if (strcmp(authmethods[i]->name, "none") == 0) 447 continue; 448 if (authmethods[i]->enabled == NULL || 449 *(authmethods[i]->enabled) == 0) 450 continue; 451 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 452 NULL)) 453 continue; 454 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 455 authmethods[i]->name)) != 0) 456 fatal_fr(r, "buffer error"); 457 } 458 if ((list = sshbuf_dup_string(b)) == NULL) 459 fatal_f("sshbuf_dup_string failed"); 460 sshbuf_free(b); 461 return list; 462 } 463 464 static Authmethod * 465 authmethod_byname(const char *name) 466 { 467 int i; 468 469 if (name == NULL) 470 fatal_f("NULL authentication method name"); 471 for (i = 0; authmethods[i] != NULL; i++) { 472 if (strcmp(name, authmethods[i]->name) == 0 || 473 (authmethods[i]->synonym != NULL && 474 strcmp(name, authmethods[i]->synonym) == 0)) 475 return authmethods[i]; 476 } 477 debug_f("unrecognized authentication method name: %s", name); 478 return NULL; 479 } 480 481 static Authmethod * 482 authmethod_lookup(Authctxt *authctxt, const char *name) 483 { 484 Authmethod *method; 485 486 if ((method = authmethod_byname(name)) == NULL) 487 return NULL; 488 489 if (method->enabled == NULL || *(method->enabled) == 0) { 490 debug3_f("method %s not enabled", name); 491 return NULL; 492 } 493 if (!auth2_method_allowed(authctxt, method->name, NULL)) { 494 debug3_f("method %s not allowed " 495 "by AuthenticationMethods", name); 496 return NULL; 497 } 498 return method; 499 } 500 501 /* 502 * Check a comma-separated list of methods for validity. Is need_enable is 503 * non-zero, then also require that the methods are enabled. 504 * Returns 0 on success or -1 if the methods list is invalid. 505 */ 506 int 507 auth2_methods_valid(const char *_methods, int need_enable) 508 { 509 char *methods, *omethods, *method, *p; 510 u_int i, found; 511 int ret = -1; 512 513 if (*_methods == '\0') { 514 error("empty authentication method list"); 515 return -1; 516 } 517 omethods = methods = xstrdup(_methods); 518 while ((method = strsep(&methods, ",")) != NULL) { 519 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 520 if ((p = strchr(method, ':')) != NULL) 521 *p = '\0'; 522 if (strcmp(method, authmethods[i]->name) != 0) 523 continue; 524 if (need_enable) { 525 if (authmethods[i]->enabled == NULL || 526 *(authmethods[i]->enabled) == 0) { 527 error("Disabled method \"%s\" in " 528 "AuthenticationMethods list \"%s\"", 529 method, _methods); 530 goto out; 531 } 532 } 533 found = 1; 534 break; 535 } 536 if (!found) { 537 error("Unknown authentication method \"%s\" in list", 538 method); 539 goto out; 540 } 541 } 542 ret = 0; 543 out: 544 free(omethods); 545 return ret; 546 } 547 548 /* 549 * Prune the AuthenticationMethods supplied in the configuration, removing 550 * any methods lists that include disabled methods. Note that this might 551 * leave authctxt->num_auth_methods == 0, even when multiple required auth 552 * has been requested. For this reason, all tests for whether multiple is 553 * enabled should consult options.num_auth_methods directly. 554 */ 555 int 556 auth2_setup_methods_lists(Authctxt *authctxt) 557 { 558 u_int i; 559 560 /* First, normalise away the "any" pseudo-method */ 561 if (options.num_auth_methods == 1 && 562 strcmp(options.auth_methods[0], "any") == 0) { 563 free(options.auth_methods[0]); 564 options.auth_methods[0] = NULL; 565 options.num_auth_methods = 0; 566 } 567 568 if (options.num_auth_methods == 0) 569 return 0; 570 debug3_f("checking methods"); 571 authctxt->auth_methods = xcalloc(options.num_auth_methods, 572 sizeof(*authctxt->auth_methods)); 573 authctxt->num_auth_methods = 0; 574 for (i = 0; i < options.num_auth_methods; i++) { 575 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 576 logit("Authentication methods list \"%s\" contains " 577 "disabled method, skipping", 578 options.auth_methods[i]); 579 continue; 580 } 581 debug("authentication methods list %d: %s", 582 authctxt->num_auth_methods, options.auth_methods[i]); 583 authctxt->auth_methods[authctxt->num_auth_methods++] = 584 xstrdup(options.auth_methods[i]); 585 } 586 if (authctxt->num_auth_methods == 0) { 587 error("No AuthenticationMethods left after eliminating " 588 "disabled methods"); 589 return -1; 590 } 591 return 0; 592 } 593 594 static int 595 list_starts_with(const char *methods, const char *method, 596 const char *submethod) 597 { 598 size_t l = strlen(method); 599 int match; 600 const char *p; 601 602 if (strncmp(methods, method, l) != 0) 603 return MATCH_NONE; 604 p = methods + l; 605 match = MATCH_METHOD; 606 if (*p == ':') { 607 if (!submethod) 608 return MATCH_PARTIAL; 609 l = strlen(submethod); 610 p += 1; 611 if (strncmp(submethod, p, l)) 612 return MATCH_NONE; 613 p += l; 614 match = MATCH_BOTH; 615 } 616 if (*p != ',' && *p != '\0') 617 return MATCH_NONE; 618 return match; 619 } 620 621 /* 622 * Remove method from the start of a comma-separated list of methods. 623 * Returns 0 if the list of methods did not start with that method or 1 624 * if it did. 625 */ 626 static int 627 remove_method(char **methods, const char *method, const char *submethod) 628 { 629 char *omethods = *methods, *p; 630 size_t l = strlen(method); 631 int match; 632 633 match = list_starts_with(omethods, method, submethod); 634 if (match != MATCH_METHOD && match != MATCH_BOTH) 635 return 0; 636 p = omethods + l; 637 if (submethod && match == MATCH_BOTH) 638 p += 1 + strlen(submethod); /* include colon */ 639 if (*p == ',') 640 p++; 641 *methods = xstrdup(p); 642 free(omethods); 643 return 1; 644 } 645 646 /* 647 * Called after successful authentication. Will remove the successful method 648 * from the start of each list in which it occurs. If it was the last method 649 * in any list, then authentication is deemed successful. 650 * Returns 1 if the method completed any authentication list or 0 otherwise. 651 */ 652 int 653 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 654 const char *submethod) 655 { 656 u_int i, found = 0; 657 658 debug3_f("updating methods list after \"%s\"", method); 659 for (i = 0; i < authctxt->num_auth_methods; i++) { 660 if (!remove_method(&(authctxt->auth_methods[i]), method, 661 submethod)) 662 continue; 663 found = 1; 664 if (*authctxt->auth_methods[i] == '\0') { 665 debug2("authentication methods list %d complete", i); 666 return 1; 667 } 668 debug3("authentication methods list %d remaining: \"%s\"", 669 i, authctxt->auth_methods[i]); 670 } 671 /* This should not happen, but would be bad if it did */ 672 if (!found) 673 fatal_f("method not in AuthenticationMethods"); 674 return 0; 675 } 676 677 /* Reset method-specific information */ 678 void auth2_authctxt_reset_info(Authctxt *authctxt) 679 { 680 sshkey_free(authctxt->auth_method_key); 681 free(authctxt->auth_method_info); 682 authctxt->auth_method_key = NULL; 683 authctxt->auth_method_info = NULL; 684 } 685 686 /* Record auth method-specific information for logs */ 687 void 688 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 689 { 690 va_list ap; 691 int i; 692 693 free(authctxt->auth_method_info); 694 authctxt->auth_method_info = NULL; 695 696 va_start(ap, fmt); 697 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 698 va_end(ap); 699 700 if (i == -1) 701 fatal_f("vasprintf failed"); 702 } 703 704 /* 705 * Records a public key used in authentication. This is used for logging 706 * and to ensure that the same key is not subsequently accepted again for 707 * multiple authentication. 708 */ 709 void 710 auth2_record_key(Authctxt *authctxt, int authenticated, 711 const struct sshkey *key) 712 { 713 struct sshkey **tmp, *dup; 714 int r; 715 716 if ((r = sshkey_from_private(key, &dup)) != 0) 717 fatal_fr(r, "copy key"); 718 sshkey_free(authctxt->auth_method_key); 719 authctxt->auth_method_key = dup; 720 721 if (!authenticated) 722 return; 723 724 /* If authenticated, make sure we don't accept this key again */ 725 if ((r = sshkey_from_private(key, &dup)) != 0) 726 fatal_fr(r, "copy key"); 727 if (authctxt->nprev_keys >= INT_MAX || 728 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 729 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 730 fatal_f("reallocarray failed"); 731 authctxt->prev_keys = tmp; 732 authctxt->prev_keys[authctxt->nprev_keys] = dup; 733 authctxt->nprev_keys++; 734 735 } 736 737 /* Checks whether a key has already been previously used for authentication */ 738 int 739 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 740 { 741 u_int i; 742 char *fp; 743 744 for (i = 0; i < authctxt->nprev_keys; i++) { 745 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 746 fp = sshkey_fingerprint(authctxt->prev_keys[i], 747 options.fingerprint_hash, SSH_FP_DEFAULT); 748 debug3_f("key already used: %s %s", 749 sshkey_type(authctxt->prev_keys[i]), 750 fp == NULL ? "UNKNOWN" : fp); 751 free(fp); 752 return 1; 753 } 754 } 755 return 0; 756 } 757 758 /* 759 * Updates authctxt->session_info with details of authentication. Should be 760 * whenever an authentication method succeeds. 761 */ 762 void 763 auth2_update_session_info(Authctxt *authctxt, const char *method, 764 const char *submethod) 765 { 766 int r; 767 768 if (authctxt->session_info == NULL) { 769 if ((authctxt->session_info = sshbuf_new()) == NULL) 770 fatal_f("sshbuf_new"); 771 } 772 773 /* Append method[/submethod] */ 774 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 775 method, submethod == NULL ? "" : "/", 776 submethod == NULL ? "" : submethod)) != 0) 777 fatal_fr(r, "append method"); 778 779 /* Append key if present */ 780 if (authctxt->auth_method_key != NULL) { 781 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 782 (r = sshkey_format_text(authctxt->auth_method_key, 783 authctxt->session_info)) != 0) 784 fatal_fr(r, "append key"); 785 } 786 787 if (authctxt->auth_method_info != NULL) { 788 /* Ensure no ambiguity here */ 789 if (strchr(authctxt->auth_method_info, '\n') != NULL) 790 fatal_f("auth_method_info contains \\n"); 791 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 792 (r = sshbuf_putf(authctxt->session_info, "%s", 793 authctxt->auth_method_info)) != 0) { 794 fatal_fr(r, "append method info"); 795 } 796 } 797 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 798 fatal_fr(r, "append"); 799 } 800 801