1 /* $OpenBSD: auth2.c,v 1.166 2023/03/08 04:43:12 guenther Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26 #include <sys/types.h> 27 #include <sys/stat.h> 28 #include <sys/uio.h> 29 30 #include <fcntl.h> 31 #include <limits.h> 32 #include <pwd.h> 33 #include <stdarg.h> 34 #include <string.h> 35 #include <unistd.h> 36 #include <time.h> 37 38 #include "stdlib.h" 39 #include "atomicio.h" 40 #include "xmalloc.h" 41 #include "ssh2.h" 42 #include "packet.h" 43 #include "log.h" 44 #include "sshbuf.h" 45 #include "misc.h" 46 #include "servconf.h" 47 #include "sshkey.h" 48 #include "hostfile.h" 49 #include "auth.h" 50 #include "dispatch.h" 51 #include "pathnames.h" 52 #ifdef GSSAPI 53 #include "ssh-gss.h" 54 #endif 55 #include "monitor_wrap.h" 56 #include "ssherr.h" 57 #include "digest.h" 58 59 /* import */ 60 extern ServerOptions options; 61 62 /* methods */ 63 64 extern Authmethod method_none; 65 extern Authmethod method_pubkey; 66 extern Authmethod method_passwd; 67 extern Authmethod method_kbdint; 68 extern Authmethod method_hostbased; 69 #ifdef GSSAPI 70 extern Authmethod method_gssapi; 71 #endif 72 73 Authmethod *authmethods[] = { 74 &method_none, 75 &method_pubkey, 76 #ifdef GSSAPI 77 &method_gssapi, 78 #endif 79 &method_passwd, 80 &method_kbdint, 81 &method_hostbased, 82 NULL 83 }; 84 85 /* protocol */ 86 87 static int input_service_request(int, u_int32_t, struct ssh *); 88 static int input_userauth_request(int, u_int32_t, struct ssh *); 89 90 /* helper */ 91 static Authmethod *authmethod_byname(const char *); 92 static Authmethod *authmethod_lookup(Authctxt *, const char *); 93 static char *authmethods_get(Authctxt *authctxt); 94 95 #define MATCH_NONE 0 /* method or submethod mismatch */ 96 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 97 #define MATCH_BOTH 2 /* method and submethod match */ 98 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 99 static int list_starts_with(const char *, const char *, const char *); 100 101 char * 102 auth2_read_banner(void) 103 { 104 struct stat st; 105 char *banner = NULL; 106 size_t len, n; 107 int fd; 108 109 if ((fd = open(options.banner, O_RDONLY)) == -1) 110 return (NULL); 111 if (fstat(fd, &st) == -1) { 112 close(fd); 113 return (NULL); 114 } 115 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 116 close(fd); 117 return (NULL); 118 } 119 120 len = (size_t)st.st_size; /* truncate */ 121 banner = xmalloc(len + 1); 122 n = atomicio(read, fd, banner, len); 123 close(fd); 124 125 if (n != len) { 126 free(banner); 127 return (NULL); 128 } 129 banner[n] = '\0'; 130 131 return (banner); 132 } 133 134 static void 135 userauth_banner(struct ssh *ssh) 136 { 137 char *banner = NULL; 138 int r; 139 140 if (options.banner == NULL) 141 return; 142 143 if ((banner = PRIVSEP(auth2_read_banner())) == NULL) 144 goto done; 145 146 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 || 147 (r = sshpkt_put_cstring(ssh, banner)) != 0 || 148 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */ 149 (r = sshpkt_send(ssh)) != 0) 150 fatal_fr(r, "send packet"); 151 debug("userauth_banner: sent"); 152 done: 153 free(banner); 154 } 155 156 /* 157 * loop until authctxt->success == TRUE 158 */ 159 void 160 do_authentication2(struct ssh *ssh) 161 { 162 Authctxt *authctxt = ssh->authctxt; 163 164 ssh_dispatch_init(ssh, &dispatch_protocol_error); 165 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); 166 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); 167 ssh->authctxt = NULL; 168 } 169 170 static int 171 input_service_request(int type, u_int32_t seq, struct ssh *ssh) 172 { 173 Authctxt *authctxt = ssh->authctxt; 174 char *service = NULL; 175 int r, acceptit = 0; 176 177 if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 178 (r = sshpkt_get_end(ssh)) != 0) 179 goto out; 180 181 if (authctxt == NULL) 182 fatal("input_service_request: no authctxt"); 183 184 if (strcmp(service, "ssh-userauth") == 0) { 185 if (!authctxt->success) { 186 acceptit = 1; 187 /* now we can handle user-auth requests */ 188 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 189 &input_userauth_request); 190 } 191 } 192 /* XXX all other service requests are denied */ 193 194 if (acceptit) { 195 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 || 196 (r = sshpkt_put_cstring(ssh, service)) != 0 || 197 (r = sshpkt_send(ssh)) != 0 || 198 (r = ssh_packet_write_wait(ssh)) != 0) 199 goto out; 200 } else { 201 debug("bad service request %s", service); 202 ssh_packet_disconnect(ssh, "bad service request %s", service); 203 } 204 r = 0; 205 out: 206 free(service); 207 return r; 208 } 209 210 #define MIN_FAIL_DELAY_SECONDS 0.005 211 static double 212 user_specific_delay(const char *user) 213 { 214 char b[512]; 215 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 216 u_char *hash = xmalloc(len); 217 double delay; 218 219 (void)snprintf(b, sizeof b, "%llu%s", 220 (unsigned long long)options.timing_secret, user); 221 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 222 fatal_f("ssh_digest_memory"); 223 /* 0-4.2 ms of delay */ 224 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 225 freezero(hash, len); 226 debug3_f("user specific delay %0.3lfms", delay/1000); 227 return MIN_FAIL_DELAY_SECONDS + delay; 228 } 229 230 static void 231 ensure_minimum_time_since(double start, double seconds) 232 { 233 struct timespec ts; 234 double elapsed = monotime_double() - start, req = seconds, remain; 235 236 /* if we've already passed the requested time, scale up */ 237 while ((remain = seconds - elapsed) < 0.0) 238 seconds *= 2; 239 240 ts.tv_sec = remain; 241 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; 242 debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 243 elapsed*1000, remain*1000, req*1000); 244 nanosleep(&ts, NULL); 245 } 246 247 static int 248 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 249 { 250 Authctxt *authctxt = ssh->authctxt; 251 Authmethod *m = NULL; 252 char *user = NULL, *service = NULL, *method = NULL, *style = NULL; 253 int r, authenticated = 0; 254 double tstart = monotime_double(); 255 256 if (authctxt == NULL) 257 fatal("input_userauth_request: no authctxt"); 258 259 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || 260 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 261 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) 262 goto out; 263 debug("userauth-request for user %s service %s method %s", user, service, method); 264 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 265 266 if ((style = strchr(user, ':')) != NULL) 267 *style++ = 0; 268 269 if (authctxt->attempt >= 1024) 270 auth_maxtries_exceeded(ssh); 271 if (authctxt->attempt++ == 0) { 272 /* setup auth context */ 273 authctxt->pw = PRIVSEP(getpwnamallow(ssh, user)); 274 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 275 authctxt->valid = 1; 276 debug2_f("setting up authctxt for %s", user); 277 } else { 278 authctxt->valid = 0; 279 /* Invalid user, fake password information */ 280 authctxt->pw = fakepw(); 281 } 282 ssh_packet_set_log_preamble(ssh, "%suser %s", 283 authctxt->valid ? "authenticating " : "invalid ", user); 284 setproctitle("%s%s", authctxt->valid ? user : "unknown", 285 use_privsep ? " [net]" : ""); 286 authctxt->user = xstrdup(user); 287 authctxt->service = xstrdup(service); 288 authctxt->style = style ? xstrdup(style) : NULL; 289 if (use_privsep) 290 mm_inform_authserv(service, style); 291 userauth_banner(ssh); 292 if (auth2_setup_methods_lists(authctxt) != 0) 293 ssh_packet_disconnect(ssh, 294 "no authentication methods enabled"); 295 } else if (strcmp(user, authctxt->user) != 0 || 296 strcmp(service, authctxt->service) != 0) { 297 ssh_packet_disconnect(ssh, "Change of username or service " 298 "not allowed: (%s,%s) -> (%s,%s)", 299 authctxt->user, authctxt->service, user, service); 300 } 301 /* reset state */ 302 auth2_challenge_stop(ssh); 303 304 #ifdef GSSAPI 305 /* XXX move to auth2_gssapi_stop() */ 306 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 307 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 308 #endif 309 310 auth2_authctxt_reset_info(authctxt); 311 authctxt->postponed = 0; 312 authctxt->server_caused_failure = 0; 313 314 /* try to authenticate user */ 315 m = authmethod_lookup(authctxt, method); 316 if (m != NULL && authctxt->failures < options.max_authtries) { 317 debug2("input_userauth_request: try method %s", method); 318 authenticated = m->userauth(ssh, method); 319 } 320 if (!authctxt->authenticated) 321 ensure_minimum_time_since(tstart, 322 user_specific_delay(authctxt->user)); 323 userauth_finish(ssh, authenticated, method, NULL); 324 r = 0; 325 out: 326 free(service); 327 free(user); 328 free(method); 329 return r; 330 } 331 332 void 333 userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method, 334 const char *submethod) 335 { 336 Authctxt *authctxt = ssh->authctxt; 337 Authmethod *m = NULL; 338 const char *method = packet_method; 339 char *methods; 340 int r, partial = 0; 341 342 if (authenticated) { 343 if (!authctxt->valid) { 344 fatal("INTERNAL ERROR: authenticated invalid user %s", 345 authctxt->user); 346 } 347 if (authctxt->postponed) 348 fatal("INTERNAL ERROR: authenticated and postponed"); 349 /* prefer primary authmethod name to possible synonym */ 350 if ((m = authmethod_byname(method)) == NULL) 351 fatal("INTERNAL ERROR: bad method %s", method); 352 method = m->name; 353 } 354 355 /* Special handling for root */ 356 if (authenticated && authctxt->pw->pw_uid == 0 && 357 !auth_root_allowed(ssh, method)) 358 authenticated = 0; 359 360 if (authenticated && options.num_auth_methods != 0) { 361 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 362 authenticated = 0; 363 partial = 1; 364 } 365 } 366 367 /* Log before sending the reply */ 368 auth_log(ssh, authenticated, partial, method, submethod); 369 370 /* Update information exposed to session */ 371 if (authenticated || partial) 372 auth2_update_session_info(authctxt, method, submethod); 373 374 if (authctxt->postponed) 375 return; 376 377 if (authenticated == 1) { 378 /* turn off userauth */ 379 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 380 &dispatch_protocol_ignore); 381 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 382 (r = sshpkt_send(ssh)) != 0 || 383 (r = ssh_packet_write_wait(ssh)) != 0) 384 fatal_fr(r, "send success packet"); 385 /* now we can break out */ 386 authctxt->success = 1; 387 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 388 } else { 389 /* Allow initial try of "none" auth without failure penalty */ 390 if (!partial && !authctxt->server_caused_failure && 391 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) 392 authctxt->failures++; 393 if (authctxt->failures >= options.max_authtries) 394 auth_maxtries_exceeded(ssh); 395 methods = authmethods_get(authctxt); 396 debug3_f("failure partial=%d next methods=\"%s\"", 397 partial, methods); 398 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 399 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 400 (r = sshpkt_put_u8(ssh, partial)) != 0 || 401 (r = sshpkt_send(ssh)) != 0 || 402 (r = ssh_packet_write_wait(ssh)) != 0) 403 fatal_fr(r, "send failure packet"); 404 free(methods); 405 } 406 } 407 408 /* 409 * Checks whether method is allowed by at least one AuthenticationMethods 410 * methods list. Returns 1 if allowed, or no methods lists configured. 411 * 0 otherwise. 412 */ 413 int 414 auth2_method_allowed(Authctxt *authctxt, const char *method, 415 const char *submethod) 416 { 417 u_int i; 418 419 /* 420 * NB. authctxt->num_auth_methods might be zero as a result of 421 * auth2_setup_methods_lists(), so check the configuration. 422 */ 423 if (options.num_auth_methods == 0) 424 return 1; 425 for (i = 0; i < authctxt->num_auth_methods; i++) { 426 if (list_starts_with(authctxt->auth_methods[i], method, 427 submethod) != MATCH_NONE) 428 return 1; 429 } 430 return 0; 431 } 432 433 static char * 434 authmethods_get(Authctxt *authctxt) 435 { 436 struct sshbuf *b; 437 char *list; 438 int i, r; 439 440 if ((b = sshbuf_new()) == NULL) 441 fatal_f("sshbuf_new failed"); 442 for (i = 0; authmethods[i] != NULL; i++) { 443 if (strcmp(authmethods[i]->name, "none") == 0) 444 continue; 445 if (authmethods[i]->enabled == NULL || 446 *(authmethods[i]->enabled) == 0) 447 continue; 448 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 449 NULL)) 450 continue; 451 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 452 authmethods[i]->name)) != 0) 453 fatal_fr(r, "buffer error"); 454 } 455 if ((list = sshbuf_dup_string(b)) == NULL) 456 fatal_f("sshbuf_dup_string failed"); 457 sshbuf_free(b); 458 return list; 459 } 460 461 static Authmethod * 462 authmethod_byname(const char *name) 463 { 464 int i; 465 466 if (name == NULL) 467 fatal_f("NULL authentication method name"); 468 for (i = 0; authmethods[i] != NULL; i++) { 469 if (strcmp(name, authmethods[i]->name) == 0 || 470 (authmethods[i]->synonym != NULL && 471 strcmp(name, authmethods[i]->synonym) == 0)) 472 return authmethods[i]; 473 } 474 debug_f("unrecognized authentication method name: %s", name); 475 return NULL; 476 } 477 478 static Authmethod * 479 authmethod_lookup(Authctxt *authctxt, const char *name) 480 { 481 Authmethod *method; 482 483 if ((method = authmethod_byname(name)) == NULL) 484 return NULL; 485 486 if (method->enabled == NULL || *(method->enabled) == 0) { 487 debug3_f("method %s not enabled", name); 488 return NULL; 489 } 490 if (!auth2_method_allowed(authctxt, method->name, NULL)) { 491 debug3_f("method %s not allowed " 492 "by AuthenticationMethods", name); 493 return NULL; 494 } 495 return method; 496 } 497 498 /* 499 * Check a comma-separated list of methods for validity. Is need_enable is 500 * non-zero, then also require that the methods are enabled. 501 * Returns 0 on success or -1 if the methods list is invalid. 502 */ 503 int 504 auth2_methods_valid(const char *_methods, int need_enable) 505 { 506 char *methods, *omethods, *method, *p; 507 u_int i, found; 508 int ret = -1; 509 510 if (*_methods == '\0') { 511 error("empty authentication method list"); 512 return -1; 513 } 514 omethods = methods = xstrdup(_methods); 515 while ((method = strsep(&methods, ",")) != NULL) { 516 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 517 if ((p = strchr(method, ':')) != NULL) 518 *p = '\0'; 519 if (strcmp(method, authmethods[i]->name) != 0) 520 continue; 521 if (need_enable) { 522 if (authmethods[i]->enabled == NULL || 523 *(authmethods[i]->enabled) == 0) { 524 error("Disabled method \"%s\" in " 525 "AuthenticationMethods list \"%s\"", 526 method, _methods); 527 goto out; 528 } 529 } 530 found = 1; 531 break; 532 } 533 if (!found) { 534 error("Unknown authentication method \"%s\" in list", 535 method); 536 goto out; 537 } 538 } 539 ret = 0; 540 out: 541 free(omethods); 542 return ret; 543 } 544 545 /* 546 * Prune the AuthenticationMethods supplied in the configuration, removing 547 * any methods lists that include disabled methods. Note that this might 548 * leave authctxt->num_auth_methods == 0, even when multiple required auth 549 * has been requested. For this reason, all tests for whether multiple is 550 * enabled should consult options.num_auth_methods directly. 551 */ 552 int 553 auth2_setup_methods_lists(Authctxt *authctxt) 554 { 555 u_int i; 556 557 /* First, normalise away the "any" pseudo-method */ 558 if (options.num_auth_methods == 1 && 559 strcmp(options.auth_methods[0], "any") == 0) { 560 free(options.auth_methods[0]); 561 options.auth_methods[0] = NULL; 562 options.num_auth_methods = 0; 563 } 564 565 if (options.num_auth_methods == 0) 566 return 0; 567 debug3_f("checking methods"); 568 authctxt->auth_methods = xcalloc(options.num_auth_methods, 569 sizeof(*authctxt->auth_methods)); 570 authctxt->num_auth_methods = 0; 571 for (i = 0; i < options.num_auth_methods; i++) { 572 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 573 logit("Authentication methods list \"%s\" contains " 574 "disabled method, skipping", 575 options.auth_methods[i]); 576 continue; 577 } 578 debug("authentication methods list %d: %s", 579 authctxt->num_auth_methods, options.auth_methods[i]); 580 authctxt->auth_methods[authctxt->num_auth_methods++] = 581 xstrdup(options.auth_methods[i]); 582 } 583 if (authctxt->num_auth_methods == 0) { 584 error("No AuthenticationMethods left after eliminating " 585 "disabled methods"); 586 return -1; 587 } 588 return 0; 589 } 590 591 static int 592 list_starts_with(const char *methods, const char *method, 593 const char *submethod) 594 { 595 size_t l = strlen(method); 596 int match; 597 const char *p; 598 599 if (strncmp(methods, method, l) != 0) 600 return MATCH_NONE; 601 p = methods + l; 602 match = MATCH_METHOD; 603 if (*p == ':') { 604 if (!submethod) 605 return MATCH_PARTIAL; 606 l = strlen(submethod); 607 p += 1; 608 if (strncmp(submethod, p, l)) 609 return MATCH_NONE; 610 p += l; 611 match = MATCH_BOTH; 612 } 613 if (*p != ',' && *p != '\0') 614 return MATCH_NONE; 615 return match; 616 } 617 618 /* 619 * Remove method from the start of a comma-separated list of methods. 620 * Returns 0 if the list of methods did not start with that method or 1 621 * if it did. 622 */ 623 static int 624 remove_method(char **methods, const char *method, const char *submethod) 625 { 626 char *omethods = *methods, *p; 627 size_t l = strlen(method); 628 int match; 629 630 match = list_starts_with(omethods, method, submethod); 631 if (match != MATCH_METHOD && match != MATCH_BOTH) 632 return 0; 633 p = omethods + l; 634 if (submethod && match == MATCH_BOTH) 635 p += 1 + strlen(submethod); /* include colon */ 636 if (*p == ',') 637 p++; 638 *methods = xstrdup(p); 639 free(omethods); 640 return 1; 641 } 642 643 /* 644 * Called after successful authentication. Will remove the successful method 645 * from the start of each list in which it occurs. If it was the last method 646 * in any list, then authentication is deemed successful. 647 * Returns 1 if the method completed any authentication list or 0 otherwise. 648 */ 649 int 650 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 651 const char *submethod) 652 { 653 u_int i, found = 0; 654 655 debug3_f("updating methods list after \"%s\"", method); 656 for (i = 0; i < authctxt->num_auth_methods; i++) { 657 if (!remove_method(&(authctxt->auth_methods[i]), method, 658 submethod)) 659 continue; 660 found = 1; 661 if (*authctxt->auth_methods[i] == '\0') { 662 debug2("authentication methods list %d complete", i); 663 return 1; 664 } 665 debug3("authentication methods list %d remaining: \"%s\"", 666 i, authctxt->auth_methods[i]); 667 } 668 /* This should not happen, but would be bad if it did */ 669 if (!found) 670 fatal_f("method not in AuthenticationMethods"); 671 return 0; 672 } 673 674 /* Reset method-specific information */ 675 void auth2_authctxt_reset_info(Authctxt *authctxt) 676 { 677 sshkey_free(authctxt->auth_method_key); 678 free(authctxt->auth_method_info); 679 authctxt->auth_method_key = NULL; 680 authctxt->auth_method_info = NULL; 681 } 682 683 /* Record auth method-specific information for logs */ 684 void 685 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 686 { 687 va_list ap; 688 int i; 689 690 free(authctxt->auth_method_info); 691 authctxt->auth_method_info = NULL; 692 693 va_start(ap, fmt); 694 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 695 va_end(ap); 696 697 if (i == -1) 698 fatal_f("vasprintf failed"); 699 } 700 701 /* 702 * Records a public key used in authentication. This is used for logging 703 * and to ensure that the same key is not subsequently accepted again for 704 * multiple authentication. 705 */ 706 void 707 auth2_record_key(Authctxt *authctxt, int authenticated, 708 const struct sshkey *key) 709 { 710 struct sshkey **tmp, *dup; 711 int r; 712 713 if ((r = sshkey_from_private(key, &dup)) != 0) 714 fatal_fr(r, "copy key"); 715 sshkey_free(authctxt->auth_method_key); 716 authctxt->auth_method_key = dup; 717 718 if (!authenticated) 719 return; 720 721 /* If authenticated, make sure we don't accept this key again */ 722 if ((r = sshkey_from_private(key, &dup)) != 0) 723 fatal_fr(r, "copy key"); 724 if (authctxt->nprev_keys >= INT_MAX || 725 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 726 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 727 fatal_f("reallocarray failed"); 728 authctxt->prev_keys = tmp; 729 authctxt->prev_keys[authctxt->nprev_keys] = dup; 730 authctxt->nprev_keys++; 731 732 } 733 734 /* Checks whether a key has already been previously used for authentication */ 735 int 736 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 737 { 738 u_int i; 739 char *fp; 740 741 for (i = 0; i < authctxt->nprev_keys; i++) { 742 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 743 fp = sshkey_fingerprint(authctxt->prev_keys[i], 744 options.fingerprint_hash, SSH_FP_DEFAULT); 745 debug3_f("key already used: %s %s", 746 sshkey_type(authctxt->prev_keys[i]), 747 fp == NULL ? "UNKNOWN" : fp); 748 free(fp); 749 return 1; 750 } 751 } 752 return 0; 753 } 754 755 /* 756 * Updates authctxt->session_info with details of authentication. Should be 757 * whenever an authentication method succeeds. 758 */ 759 void 760 auth2_update_session_info(Authctxt *authctxt, const char *method, 761 const char *submethod) 762 { 763 int r; 764 765 if (authctxt->session_info == NULL) { 766 if ((authctxt->session_info = sshbuf_new()) == NULL) 767 fatal_f("sshbuf_new"); 768 } 769 770 /* Append method[/submethod] */ 771 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 772 method, submethod == NULL ? "" : "/", 773 submethod == NULL ? "" : submethod)) != 0) 774 fatal_fr(r, "append method"); 775 776 /* Append key if present */ 777 if (authctxt->auth_method_key != NULL) { 778 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 779 (r = sshkey_format_text(authctxt->auth_method_key, 780 authctxt->session_info)) != 0) 781 fatal_fr(r, "append key"); 782 } 783 784 if (authctxt->auth_method_info != NULL) { 785 /* Ensure no ambiguity here */ 786 if (strchr(authctxt->auth_method_info, '\n') != NULL) 787 fatal_f("auth_method_info contains \\n"); 788 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 789 (r = sshbuf_putf(authctxt->session_info, "%s", 790 authctxt->auth_method_info)) != 0) { 791 fatal_fr(r, "append method info"); 792 } 793 } 794 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 795 fatal_fr(r, "append"); 796 } 797 798