1 /* $OpenBSD: auth2.c,v 1.159 2020/10/18 11:32:01 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 extern u_char *session_id2; 63 extern u_int session_id2_len; 64 65 /* methods */ 66 67 extern Authmethod method_none; 68 extern Authmethod method_pubkey; 69 extern Authmethod method_passwd; 70 extern Authmethod method_kbdint; 71 extern Authmethod method_hostbased; 72 #ifdef GSSAPI 73 extern Authmethod method_gssapi; 74 #endif 75 76 Authmethod *authmethods[] = { 77 &method_none, 78 &method_pubkey, 79 #ifdef GSSAPI 80 &method_gssapi, 81 #endif 82 &method_passwd, 83 &method_kbdint, 84 &method_hostbased, 85 NULL 86 }; 87 88 /* protocol */ 89 90 static int input_service_request(int, u_int32_t, struct ssh *); 91 static int input_userauth_request(int, u_int32_t, struct ssh *); 92 93 /* helper */ 94 static Authmethod *authmethod_lookup(Authctxt *, const char *); 95 static char *authmethods_get(Authctxt *authctxt); 96 97 #define MATCH_NONE 0 /* method or submethod mismatch */ 98 #define MATCH_METHOD 1 /* method matches (no submethod specified) */ 99 #define MATCH_BOTH 2 /* method and submethod match */ 100 #define MATCH_PARTIAL 3 /* method matches, submethod can't be checked */ 101 static int list_starts_with(const char *, const char *, const char *); 102 103 char * 104 auth2_read_banner(void) 105 { 106 struct stat st; 107 char *banner = NULL; 108 size_t len, n; 109 int fd; 110 111 if ((fd = open(options.banner, O_RDONLY)) == -1) 112 return (NULL); 113 if (fstat(fd, &st) == -1) { 114 close(fd); 115 return (NULL); 116 } 117 if (st.st_size <= 0 || st.st_size > 1*1024*1024) { 118 close(fd); 119 return (NULL); 120 } 121 122 len = (size_t)st.st_size; /* truncate */ 123 banner = xmalloc(len + 1); 124 n = atomicio(read, fd, banner, len); 125 close(fd); 126 127 if (n != len) { 128 free(banner); 129 return (NULL); 130 } 131 banner[n] = '\0'; 132 133 return (banner); 134 } 135 136 static void 137 userauth_banner(struct ssh *ssh) 138 { 139 char *banner = NULL; 140 int r; 141 142 if (options.banner == NULL) 143 return; 144 145 if ((banner = PRIVSEP(auth2_read_banner())) == NULL) 146 goto done; 147 148 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_BANNER)) != 0 || 149 (r = sshpkt_put_cstring(ssh, banner)) != 0 || 150 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* language, unused */ 151 (r = sshpkt_send(ssh)) != 0) 152 fatal_fr(r, "send packet"); 153 debug("userauth_banner: sent"); 154 done: 155 free(banner); 156 } 157 158 /* 159 * loop until authctxt->success == TRUE 160 */ 161 void 162 do_authentication2(struct ssh *ssh) 163 { 164 Authctxt *authctxt = ssh->authctxt; 165 166 ssh_dispatch_init(ssh, &dispatch_protocol_error); 167 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); 168 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); 169 ssh->authctxt = NULL; 170 } 171 172 /*ARGSUSED*/ 173 static int 174 input_service_request(int type, u_int32_t seq, struct ssh *ssh) 175 { 176 Authctxt *authctxt = ssh->authctxt; 177 char *service = NULL; 178 int r, acceptit = 0; 179 180 if ((r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 181 (r = sshpkt_get_end(ssh)) != 0) 182 goto out; 183 184 if (authctxt == NULL) 185 fatal("input_service_request: no authctxt"); 186 187 if (strcmp(service, "ssh-userauth") == 0) { 188 if (!authctxt->success) { 189 acceptit = 1; 190 /* now we can handle user-auth requests */ 191 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 192 &input_userauth_request); 193 } 194 } 195 /* XXX all other service requests are denied */ 196 197 if (acceptit) { 198 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_ACCEPT)) != 0 || 199 (r = sshpkt_put_cstring(ssh, service)) != 0 || 200 (r = sshpkt_send(ssh)) != 0 || 201 (r = ssh_packet_write_wait(ssh)) != 0) 202 goto out; 203 } else { 204 debug("bad service request %s", service); 205 ssh_packet_disconnect(ssh, "bad service request %s", service); 206 } 207 r = 0; 208 out: 209 free(service); 210 return r; 211 } 212 213 #define MIN_FAIL_DELAY_SECONDS 0.005 214 static double 215 user_specific_delay(const char *user) 216 { 217 char b[512]; 218 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 219 u_char *hash = xmalloc(len); 220 double delay; 221 222 (void)snprintf(b, sizeof b, "%llu%s", 223 (unsigned long long)options.timing_secret, user); 224 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 225 fatal_f("ssh_digest_memory"); 226 /* 0-4.2 ms of delay */ 227 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 228 freezero(hash, len); 229 debug3_f("user specific delay %0.3lfms", delay/1000); 230 return MIN_FAIL_DELAY_SECONDS + delay; 231 } 232 233 static void 234 ensure_minimum_time_since(double start, double seconds) 235 { 236 struct timespec ts; 237 double elapsed = monotime_double() - start, req = seconds, remain; 238 239 /* if we've already passed the requested time, scale up */ 240 while ((remain = seconds - elapsed) < 0.0) 241 seconds *= 2; 242 243 ts.tv_sec = remain; 244 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; 245 debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 246 elapsed*1000, remain*1000, req*1000); 247 nanosleep(&ts, NULL); 248 } 249 250 /*ARGSUSED*/ 251 static int 252 input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 253 { 254 Authctxt *authctxt = ssh->authctxt; 255 Authmethod *m = NULL; 256 char *user = NULL, *service = NULL, *method = NULL, *style = NULL; 257 int r, authenticated = 0; 258 double tstart = monotime_double(); 259 260 if (authctxt == NULL) 261 fatal("input_userauth_request: no authctxt"); 262 263 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || 264 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 265 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) 266 goto out; 267 debug("userauth-request for user %s service %s method %s", user, service, method); 268 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 269 270 if ((style = strchr(user, ':')) != NULL) 271 *style++ = 0; 272 273 if (authctxt->attempt++ == 0) { 274 /* setup auth context */ 275 authctxt->pw = PRIVSEP(getpwnamallow(ssh, user)); 276 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 277 authctxt->valid = 1; 278 debug2_f("setting up authctxt for %s", user); 279 } else { 280 /* Invalid user, fake password information */ 281 authctxt->pw = fakepw(); 282 } 283 ssh_packet_set_log_preamble(ssh, "%suser %s", 284 authctxt->valid ? "authenticating " : "invalid ", user); 285 setproctitle("%s%s", authctxt->valid ? user : "unknown", 286 use_privsep ? " [net]" : ""); 287 authctxt->user = xstrdup(user); 288 authctxt->service = xstrdup(service); 289 authctxt->style = style ? xstrdup(style) : NULL; 290 if (use_privsep) 291 mm_inform_authserv(service, style); 292 userauth_banner(ssh); 293 if (auth2_setup_methods_lists(authctxt) != 0) 294 ssh_packet_disconnect(ssh, 295 "no authentication methods enabled"); 296 } else if (strcmp(user, authctxt->user) != 0 || 297 strcmp(service, authctxt->service) != 0) { 298 ssh_packet_disconnect(ssh, "Change of username or service " 299 "not allowed: (%s,%s) -> (%s,%s)", 300 authctxt->user, authctxt->service, user, service); 301 } 302 /* reset state */ 303 auth2_challenge_stop(ssh); 304 305 #ifdef GSSAPI 306 /* XXX move to auth2_gssapi_stop() */ 307 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 308 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 309 #endif 310 311 auth2_authctxt_reset_info(authctxt); 312 authctxt->postponed = 0; 313 authctxt->server_caused_failure = 0; 314 315 /* try to authenticate user */ 316 m = authmethod_lookup(authctxt, method); 317 if (m != NULL && authctxt->failures < options.max_authtries) { 318 debug2("input_userauth_request: try method %s", method); 319 authenticated = m->userauth(ssh); 320 } 321 if (!authctxt->authenticated) 322 ensure_minimum_time_since(tstart, 323 user_specific_delay(authctxt->user)); 324 userauth_finish(ssh, authenticated, method, NULL); 325 r = 0; 326 out: 327 free(service); 328 free(user); 329 free(method); 330 return r; 331 } 332 333 void 334 userauth_finish(struct ssh *ssh, int authenticated, const char *method, 335 const char *submethod) 336 { 337 Authctxt *authctxt = ssh->authctxt; 338 char *methods; 339 int r, partial = 0; 340 341 if (!authctxt->valid && authenticated) 342 fatal("INTERNAL ERROR: authenticated invalid user %s", 343 authctxt->user); 344 if (authenticated && authctxt->postponed) 345 fatal("INTERNAL ERROR: authenticated and postponed"); 346 347 /* Special handling for root */ 348 if (authenticated && authctxt->pw->pw_uid == 0 && 349 !auth_root_allowed(ssh, method)) 350 authenticated = 0; 351 352 if (authenticated && options.num_auth_methods != 0) { 353 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 354 authenticated = 0; 355 partial = 1; 356 } 357 } 358 359 /* Log before sending the reply */ 360 auth_log(ssh, authenticated, partial, method, submethod); 361 362 /* Update information exposed to session */ 363 if (authenticated || partial) 364 auth2_update_session_info(authctxt, method, submethod); 365 366 if (authctxt->postponed) 367 return; 368 369 if (authenticated == 1) { 370 /* turn off userauth */ 371 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 372 &dispatch_protocol_ignore); 373 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 374 (r = sshpkt_send(ssh)) != 0 || 375 (r = ssh_packet_write_wait(ssh)) != 0) 376 fatal_fr(r, "send success packet"); 377 /* now we can break out */ 378 authctxt->success = 1; 379 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 380 } else { 381 /* Allow initial try of "none" auth without failure penalty */ 382 if (!partial && !authctxt->server_caused_failure && 383 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) 384 authctxt->failures++; 385 if (authctxt->failures >= options.max_authtries) 386 auth_maxtries_exceeded(ssh); 387 methods = authmethods_get(authctxt); 388 debug3_f("failure partial=%d next methods=\"%s\"", 389 partial, methods); 390 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 391 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 392 (r = sshpkt_put_u8(ssh, partial)) != 0 || 393 (r = sshpkt_send(ssh)) != 0 || 394 (r = ssh_packet_write_wait(ssh)) != 0) 395 fatal_fr(r, "send failure packet"); 396 free(methods); 397 } 398 } 399 400 /* 401 * Checks whether method is allowed by at least one AuthenticationMethods 402 * methods list. Returns 1 if allowed, or no methods lists configured. 403 * 0 otherwise. 404 */ 405 int 406 auth2_method_allowed(Authctxt *authctxt, const char *method, 407 const char *submethod) 408 { 409 u_int i; 410 411 /* 412 * NB. authctxt->num_auth_methods might be zero as a result of 413 * auth2_setup_methods_lists(), so check the configuration. 414 */ 415 if (options.num_auth_methods == 0) 416 return 1; 417 for (i = 0; i < authctxt->num_auth_methods; i++) { 418 if (list_starts_with(authctxt->auth_methods[i], method, 419 submethod) != MATCH_NONE) 420 return 1; 421 } 422 return 0; 423 } 424 425 static char * 426 authmethods_get(Authctxt *authctxt) 427 { 428 struct sshbuf *b; 429 char *list; 430 int i, r; 431 432 if ((b = sshbuf_new()) == NULL) 433 fatal_f("sshbuf_new failed"); 434 for (i = 0; authmethods[i] != NULL; i++) { 435 if (strcmp(authmethods[i]->name, "none") == 0) 436 continue; 437 if (authmethods[i]->enabled == NULL || 438 *(authmethods[i]->enabled) == 0) 439 continue; 440 if (!auth2_method_allowed(authctxt, authmethods[i]->name, 441 NULL)) 442 continue; 443 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 444 authmethods[i]->name)) != 0) 445 fatal_fr(r, "buffer error"); 446 } 447 if ((list = sshbuf_dup_string(b)) == NULL) 448 fatal_f("sshbuf_dup_string failed"); 449 sshbuf_free(b); 450 return list; 451 } 452 453 static Authmethod * 454 authmethod_lookup(Authctxt *authctxt, const char *name) 455 { 456 int i; 457 458 if (name != NULL) 459 for (i = 0; authmethods[i] != NULL; i++) 460 if (authmethods[i]->enabled != NULL && 461 *(authmethods[i]->enabled) != 0 && 462 strcmp(name, authmethods[i]->name) == 0 && 463 auth2_method_allowed(authctxt, 464 authmethods[i]->name, NULL)) 465 return authmethods[i]; 466 debug2("Unrecognized authentication method name: %s", 467 name ? name : "NULL"); 468 return NULL; 469 } 470 471 /* 472 * Check a comma-separated list of methods for validity. Is need_enable is 473 * non-zero, then also require that the methods are enabled. 474 * Returns 0 on success or -1 if the methods list is invalid. 475 */ 476 int 477 auth2_methods_valid(const char *_methods, int need_enable) 478 { 479 char *methods, *omethods, *method, *p; 480 u_int i, found; 481 int ret = -1; 482 483 if (*_methods == '\0') { 484 error("empty authentication method list"); 485 return -1; 486 } 487 omethods = methods = xstrdup(_methods); 488 while ((method = strsep(&methods, ",")) != NULL) { 489 for (found = i = 0; !found && authmethods[i] != NULL; i++) { 490 if ((p = strchr(method, ':')) != NULL) 491 *p = '\0'; 492 if (strcmp(method, authmethods[i]->name) != 0) 493 continue; 494 if (need_enable) { 495 if (authmethods[i]->enabled == NULL || 496 *(authmethods[i]->enabled) == 0) { 497 error("Disabled method \"%s\" in " 498 "AuthenticationMethods list \"%s\"", 499 method, _methods); 500 goto out; 501 } 502 } 503 found = 1; 504 break; 505 } 506 if (!found) { 507 error("Unknown authentication method \"%s\" in list", 508 method); 509 goto out; 510 } 511 } 512 ret = 0; 513 out: 514 free(omethods); 515 return ret; 516 } 517 518 /* 519 * Prune the AuthenticationMethods supplied in the configuration, removing 520 * any methods lists that include disabled methods. Note that this might 521 * leave authctxt->num_auth_methods == 0, even when multiple required auth 522 * has been requested. For this reason, all tests for whether multiple is 523 * enabled should consult options.num_auth_methods directly. 524 */ 525 int 526 auth2_setup_methods_lists(Authctxt *authctxt) 527 { 528 u_int i; 529 530 /* First, normalise away the "any" pseudo-method */ 531 if (options.num_auth_methods == 1 && 532 strcmp(options.auth_methods[0], "any") == 0) { 533 free(options.auth_methods[0]); 534 options.auth_methods[0] = NULL; 535 options.num_auth_methods = 0; 536 } 537 538 if (options.num_auth_methods == 0) 539 return 0; 540 debug3_f("checking methods"); 541 authctxt->auth_methods = xcalloc(options.num_auth_methods, 542 sizeof(*authctxt->auth_methods)); 543 authctxt->num_auth_methods = 0; 544 for (i = 0; i < options.num_auth_methods; i++) { 545 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 546 logit("Authentication methods list \"%s\" contains " 547 "disabled method, skipping", 548 options.auth_methods[i]); 549 continue; 550 } 551 debug("authentication methods list %d: %s", 552 authctxt->num_auth_methods, options.auth_methods[i]); 553 authctxt->auth_methods[authctxt->num_auth_methods++] = 554 xstrdup(options.auth_methods[i]); 555 } 556 if (authctxt->num_auth_methods == 0) { 557 error("No AuthenticationMethods left after eliminating " 558 "disabled methods"); 559 return -1; 560 } 561 return 0; 562 } 563 564 static int 565 list_starts_with(const char *methods, const char *method, 566 const char *submethod) 567 { 568 size_t l = strlen(method); 569 int match; 570 const char *p; 571 572 if (strncmp(methods, method, l) != 0) 573 return MATCH_NONE; 574 p = methods + l; 575 match = MATCH_METHOD; 576 if (*p == ':') { 577 if (!submethod) 578 return MATCH_PARTIAL; 579 l = strlen(submethod); 580 p += 1; 581 if (strncmp(submethod, p, l)) 582 return MATCH_NONE; 583 p += l; 584 match = MATCH_BOTH; 585 } 586 if (*p != ',' && *p != '\0') 587 return MATCH_NONE; 588 return match; 589 } 590 591 /* 592 * Remove method from the start of a comma-separated list of methods. 593 * Returns 0 if the list of methods did not start with that method or 1 594 * if it did. 595 */ 596 static int 597 remove_method(char **methods, const char *method, const char *submethod) 598 { 599 char *omethods = *methods, *p; 600 size_t l = strlen(method); 601 int match; 602 603 match = list_starts_with(omethods, method, submethod); 604 if (match != MATCH_METHOD && match != MATCH_BOTH) 605 return 0; 606 p = omethods + l; 607 if (submethod && match == MATCH_BOTH) 608 p += 1 + strlen(submethod); /* include colon */ 609 if (*p == ',') 610 p++; 611 *methods = xstrdup(p); 612 free(omethods); 613 return 1; 614 } 615 616 /* 617 * Called after successful authentication. Will remove the successful method 618 * from the start of each list in which it occurs. If it was the last method 619 * in any list, then authentication is deemed successful. 620 * Returns 1 if the method completed any authentication list or 0 otherwise. 621 */ 622 int 623 auth2_update_methods_lists(Authctxt *authctxt, const char *method, 624 const char *submethod) 625 { 626 u_int i, found = 0; 627 628 debug3_f("updating methods list after \"%s\"", method); 629 for (i = 0; i < authctxt->num_auth_methods; i++) { 630 if (!remove_method(&(authctxt->auth_methods[i]), method, 631 submethod)) 632 continue; 633 found = 1; 634 if (*authctxt->auth_methods[i] == '\0') { 635 debug2("authentication methods list %d complete", i); 636 return 1; 637 } 638 debug3("authentication methods list %d remaining: \"%s\"", 639 i, authctxt->auth_methods[i]); 640 } 641 /* This should not happen, but would be bad if it did */ 642 if (!found) 643 fatal_f("method not in AuthenticationMethods"); 644 return 0; 645 } 646 647 /* Reset method-specific information */ 648 void auth2_authctxt_reset_info(Authctxt *authctxt) 649 { 650 sshkey_free(authctxt->auth_method_key); 651 free(authctxt->auth_method_info); 652 authctxt->auth_method_key = NULL; 653 authctxt->auth_method_info = NULL; 654 } 655 656 /* Record auth method-specific information for logs */ 657 void 658 auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 659 { 660 va_list ap; 661 int i; 662 663 free(authctxt->auth_method_info); 664 authctxt->auth_method_info = NULL; 665 666 va_start(ap, fmt); 667 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 668 va_end(ap); 669 670 if (i == -1) 671 fatal_f("vasprintf failed"); 672 } 673 674 /* 675 * Records a public key used in authentication. This is used for logging 676 * and to ensure that the same key is not subsequently accepted again for 677 * multiple authentication. 678 */ 679 void 680 auth2_record_key(Authctxt *authctxt, int authenticated, 681 const struct sshkey *key) 682 { 683 struct sshkey **tmp, *dup; 684 int r; 685 686 if ((r = sshkey_from_private(key, &dup)) != 0) 687 fatal_fr(r, "copy key"); 688 sshkey_free(authctxt->auth_method_key); 689 authctxt->auth_method_key = dup; 690 691 if (!authenticated) 692 return; 693 694 /* If authenticated, make sure we don't accept this key again */ 695 if ((r = sshkey_from_private(key, &dup)) != 0) 696 fatal_fr(r, "copy key"); 697 if (authctxt->nprev_keys >= INT_MAX || 698 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 699 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 700 fatal_f("reallocarray failed"); 701 authctxt->prev_keys = tmp; 702 authctxt->prev_keys[authctxt->nprev_keys] = dup; 703 authctxt->nprev_keys++; 704 705 } 706 707 /* Checks whether a key has already been previously used for authentication */ 708 int 709 auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 710 { 711 u_int i; 712 char *fp; 713 714 for (i = 0; i < authctxt->nprev_keys; i++) { 715 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 716 fp = sshkey_fingerprint(authctxt->prev_keys[i], 717 options.fingerprint_hash, SSH_FP_DEFAULT); 718 debug3_f("key already used: %s %s", 719 sshkey_type(authctxt->prev_keys[i]), 720 fp == NULL ? "UNKNOWN" : fp); 721 free(fp); 722 return 1; 723 } 724 } 725 return 0; 726 } 727 728 /* 729 * Updates authctxt->session_info with details of authentication. Should be 730 * whenever an authentication method succeeds. 731 */ 732 void 733 auth2_update_session_info(Authctxt *authctxt, const char *method, 734 const char *submethod) 735 { 736 int r; 737 738 if (authctxt->session_info == NULL) { 739 if ((authctxt->session_info = sshbuf_new()) == NULL) 740 fatal_f("sshbuf_new"); 741 } 742 743 /* Append method[/submethod] */ 744 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 745 method, submethod == NULL ? "" : "/", 746 submethod == NULL ? "" : submethod)) != 0) 747 fatal_fr(r, "append method"); 748 749 /* Append key if present */ 750 if (authctxt->auth_method_key != NULL) { 751 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 752 (r = sshkey_format_text(authctxt->auth_method_key, 753 authctxt->session_info)) != 0) 754 fatal_fr(r, "append key"); 755 } 756 757 if (authctxt->auth_method_info != NULL) { 758 /* Ensure no ambiguity here */ 759 if (strchr(authctxt->auth_method_info, '\n') != NULL) 760 fatal_f("auth_method_info contains \\n"); 761 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 762 (r = sshbuf_putf(authctxt->session_info, "%s", 763 authctxt->auth_method_info)) != 0) { 764 fatal_fr(r, "append method info"); 765 } 766 } 767 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 768 fatal_fr(r, "append"); 769 } 770 771