1/* $OpenBSD: auth2.c,v 1.169 2024/05/17 00:30:23 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 "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#include "kex.h" 59 60/* import */ 61extern ServerOptions options; 62 63/* methods */ 64 65extern Authmethod method_none; 66extern Authmethod method_pubkey; 67extern Authmethod method_passwd; 68extern Authmethod method_kbdint; 69extern Authmethod method_hostbased; 70#ifdef GSSAPI 71extern Authmethod method_gssapi; 72#endif 73 74Authmethod *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 88static int input_service_request(int, u_int32_t, struct ssh *); 89static int input_userauth_request(int, u_int32_t, struct ssh *); 90 91/* helper */ 92static Authmethod *authmethod_byname(const char *); 93static Authmethod *authmethod_lookup(Authctxt *, const char *); 94static 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 */ 100static int list_starts_with(const char *, const char *, const char *); 101 102char * 103auth2_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 135static void 136userauth_banner(struct ssh *ssh) 137{ 138 char *banner = NULL; 139 int r; 140 141 if (options.banner == NULL) 142 return; 143 144 if ((banner = mm_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"); 153done: 154 free(banner); 155} 156 157/* 158 * loop until authctxt->success == TRUE 159 */ 160void 161do_authentication2(struct ssh *ssh) 162{ 163 Authctxt *authctxt = ssh->authctxt; 164 165 ssh_dispatch_init(ssh, &dispatch_protocol_error); 166 if (ssh->kex->ext_info_c) 167 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &kex_input_ext_info); 168 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_REQUEST, &input_service_request); 169 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt->success); 170 ssh->authctxt = NULL; 171} 172 173static int 174input_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 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &dispatch_protocol_error); 208 r = 0; 209 out: 210 free(service); 211 return r; 212} 213 214#define MIN_FAIL_DELAY_SECONDS 0.005 215#define MAX_FAIL_DELAY_SECONDS 5.0 216static double 217user_specific_delay(const char *user) 218{ 219 char b[512]; 220 size_t len = ssh_digest_bytes(SSH_DIGEST_SHA512); 221 u_char *hash = xmalloc(len); 222 double delay; 223 224 (void)snprintf(b, sizeof b, "%llu%s", 225 (unsigned long long)options.timing_secret, user); 226 if (ssh_digest_memory(SSH_DIGEST_SHA512, b, strlen(b), hash, len) != 0) 227 fatal_f("ssh_digest_memory"); 228 /* 0-4.2 ms of delay */ 229 delay = (double)PEEK_U32(hash) / 1000 / 1000 / 1000 / 1000; 230 freezero(hash, len); 231 debug3_f("user specific delay %0.3lfms", delay/1000); 232 return MIN_FAIL_DELAY_SECONDS + delay; 233} 234 235static void 236ensure_minimum_time_since(double start, double seconds) 237{ 238 struct timespec ts; 239 double elapsed = monotime_double() - start, req = seconds, remain; 240 241 if (elapsed > MAX_FAIL_DELAY_SECONDS) { 242 debug3_f("elapsed %0.3lfms exceeded the max delay " 243 "requested %0.3lfms)", elapsed*1000, req*1000); 244 return; 245 } 246 247 /* if we've already passed the requested time, scale up */ 248 while ((remain = seconds - elapsed) < 0.0) 249 seconds *= 2; 250 251 ts.tv_sec = remain; 252 ts.tv_nsec = (remain - ts.tv_sec) * 1000000000; 253 debug3_f("elapsed %0.3lfms, delaying %0.3lfms (requested %0.3lfms)", 254 elapsed*1000, remain*1000, req*1000); 255 nanosleep(&ts, NULL); 256} 257 258static int 259input_userauth_request(int type, u_int32_t seq, struct ssh *ssh) 260{ 261 Authctxt *authctxt = ssh->authctxt; 262 Authmethod *m = NULL; 263 char *user = NULL, *service = NULL, *method = NULL, *style = NULL; 264 int r, authenticated = 0; 265 double tstart = monotime_double(); 266 267 if (authctxt == NULL) 268 fatal("input_userauth_request: no authctxt"); 269 270 if ((r = sshpkt_get_cstring(ssh, &user, NULL)) != 0 || 271 (r = sshpkt_get_cstring(ssh, &service, NULL)) != 0 || 272 (r = sshpkt_get_cstring(ssh, &method, NULL)) != 0) 273 goto out; 274 debug("userauth-request for user %s service %s method %s", user, service, method); 275 debug("attempt %d failures %d", authctxt->attempt, authctxt->failures); 276 277 if ((style = strchr(user, ':')) != NULL) 278 *style++ = 0; 279 280 if (authctxt->attempt >= 1024) 281 auth_maxtries_exceeded(ssh); 282 if (authctxt->attempt++ == 0) { 283 /* setup auth context */ 284 authctxt->pw = mm_getpwnamallow(ssh, user); 285 if (authctxt->pw && strcmp(service, "ssh-connection")==0) { 286 authctxt->valid = 1; 287 debug2_f("setting up authctxt for %s", user); 288 } else { 289 authctxt->valid = 0; 290 /* Invalid user, fake password information */ 291 authctxt->pw = fakepw(); 292 } 293 ssh_packet_set_log_preamble(ssh, "%suser %s", 294 authctxt->valid ? "authenticating " : "invalid ", user); 295 setproctitle("%s [net]", authctxt->valid ? user : "unknown"); 296 authctxt->user = xstrdup(user); 297 authctxt->service = xstrdup(service); 298 authctxt->style = style ? xstrdup(style) : NULL; 299 mm_inform_authserv(service, style); 300 userauth_banner(ssh); 301 if ((r = kex_server_update_ext_info(ssh)) != 0) 302 fatal_fr(r, "kex_server_update_ext_info failed"); 303 if (auth2_setup_methods_lists(authctxt) != 0) 304 ssh_packet_disconnect(ssh, 305 "no authentication methods enabled"); 306 } else if (strcmp(user, authctxt->user) != 0 || 307 strcmp(service, authctxt->service) != 0) { 308 ssh_packet_disconnect(ssh, "Change of username or service " 309 "not allowed: (%s,%s) -> (%s,%s)", 310 authctxt->user, authctxt->service, user, service); 311 } 312 /* reset state */ 313 auth2_challenge_stop(ssh); 314 315#ifdef GSSAPI 316 /* XXX move to auth2_gssapi_stop() */ 317 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, NULL); 318 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE, NULL); 319#endif 320 321 auth2_authctxt_reset_info(authctxt); 322 authctxt->postponed = 0; 323 authctxt->server_caused_failure = 0; 324 325 /* try to authenticate user */ 326 m = authmethod_lookup(authctxt, method); 327 if (m != NULL && authctxt->failures < options.max_authtries) { 328 debug2("input_userauth_request: try method %s", method); 329 authenticated = m->userauth(ssh, method); 330 } 331 if (!authctxt->authenticated && strcmp(method, "none") != 0) 332 ensure_minimum_time_since(tstart, 333 user_specific_delay(authctxt->user)); 334 userauth_finish(ssh, authenticated, method, NULL); 335 r = 0; 336 out: 337 free(service); 338 free(user); 339 free(method); 340 return r; 341} 342 343void 344userauth_finish(struct ssh *ssh, int authenticated, const char *packet_method, 345 const char *submethod) 346{ 347 Authctxt *authctxt = ssh->authctxt; 348 Authmethod *m = NULL; 349 const char *method = packet_method; 350 char *methods; 351 int r, partial = 0; 352 353 if (authenticated) { 354 if (!authctxt->valid) { 355 fatal("INTERNAL ERROR: authenticated invalid user %s", 356 authctxt->user); 357 } 358 if (authctxt->postponed) 359 fatal("INTERNAL ERROR: authenticated and postponed"); 360 /* prefer primary authmethod name to possible synonym */ 361 if ((m = authmethod_byname(method)) == NULL) 362 fatal("INTERNAL ERROR: bad method %s", method); 363 method = m->cfg->name; 364 } 365 366 /* Special handling for root */ 367 if (authenticated && authctxt->pw->pw_uid == 0 && 368 !auth_root_allowed(ssh, method)) 369 authenticated = 0; 370 371 if (authenticated && options.num_auth_methods != 0) { 372 if (!auth2_update_methods_lists(authctxt, method, submethod)) { 373 authenticated = 0; 374 partial = 1; 375 } 376 } 377 378 /* Log before sending the reply */ 379 auth_log(ssh, authenticated, partial, method, submethod); 380 381 /* Update information exposed to session */ 382 if (authenticated || partial) 383 auth2_update_session_info(authctxt, method, submethod); 384 385 if (authctxt->postponed) 386 return; 387 388 if (authenticated == 1) { 389 /* turn off userauth */ 390 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_REQUEST, 391 &dispatch_protocol_ignore); 392 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_SUCCESS)) != 0 || 393 (r = sshpkt_send(ssh)) != 0 || 394 (r = ssh_packet_write_wait(ssh)) != 0) 395 fatal_fr(r, "send success packet"); 396 /* now we can break out */ 397 authctxt->success = 1; 398 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 399 } else { 400 /* Allow initial try of "none" auth without failure penalty */ 401 if (!partial && !authctxt->server_caused_failure && 402 (authctxt->attempt > 1 || strcmp(method, "none") != 0)) 403 authctxt->failures++; 404 if (authctxt->failures >= options.max_authtries) 405 auth_maxtries_exceeded(ssh); 406 methods = authmethods_get(authctxt); 407 debug3_f("failure partial=%d next methods=\"%s\"", 408 partial, methods); 409 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_FAILURE)) != 0 || 410 (r = sshpkt_put_cstring(ssh, methods)) != 0 || 411 (r = sshpkt_put_u8(ssh, partial)) != 0 || 412 (r = sshpkt_send(ssh)) != 0 || 413 (r = ssh_packet_write_wait(ssh)) != 0) 414 fatal_fr(r, "send failure packet"); 415 free(methods); 416 } 417} 418 419/* 420 * Checks whether method is allowed by at least one AuthenticationMethods 421 * methods list. Returns 1 if allowed, or no methods lists configured. 422 * 0 otherwise. 423 */ 424int 425auth2_method_allowed(Authctxt *authctxt, const char *method, 426 const char *submethod) 427{ 428 u_int i; 429 430 /* 431 * NB. authctxt->num_auth_methods might be zero as a result of 432 * auth2_setup_methods_lists(), so check the configuration. 433 */ 434 if (options.num_auth_methods == 0) 435 return 1; 436 for (i = 0; i < authctxt->num_auth_methods; i++) { 437 if (list_starts_with(authctxt->auth_methods[i], method, 438 submethod) != MATCH_NONE) 439 return 1; 440 } 441 return 0; 442} 443 444static char * 445authmethods_get(Authctxt *authctxt) 446{ 447 struct sshbuf *b; 448 char *list; 449 int i, r; 450 451 if ((b = sshbuf_new()) == NULL) 452 fatal_f("sshbuf_new failed"); 453 for (i = 0; authmethods[i] != NULL; i++) { 454 if (strcmp(authmethods[i]->cfg->name, "none") == 0) 455 continue; 456 if (authmethods[i]->cfg->enabled == NULL || 457 *(authmethods[i]->cfg->enabled) == 0) 458 continue; 459 if (!auth2_method_allowed(authctxt, authmethods[i]->cfg->name, 460 NULL)) 461 continue; 462 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) ? "," : "", 463 authmethods[i]->cfg->name)) != 0) 464 fatal_fr(r, "buffer error"); 465 } 466 if ((list = sshbuf_dup_string(b)) == NULL) 467 fatal_f("sshbuf_dup_string failed"); 468 sshbuf_free(b); 469 return list; 470} 471 472static Authmethod * 473authmethod_byname(const char *name) 474{ 475 int i; 476 477 if (name == NULL) 478 fatal_f("NULL authentication method name"); 479 for (i = 0; authmethods[i] != NULL; i++) { 480 if (strcmp(name, authmethods[i]->cfg->name) == 0 || 481 (authmethods[i]->cfg->synonym != NULL && 482 strcmp(name, authmethods[i]->cfg->synonym) == 0)) 483 return authmethods[i]; 484 } 485 debug_f("unrecognized authentication method name: %s", name); 486 return NULL; 487} 488 489static Authmethod * 490authmethod_lookup(Authctxt *authctxt, const char *name) 491{ 492 Authmethod *method; 493 494 if ((method = authmethod_byname(name)) == NULL) 495 return NULL; 496 497 if (method->cfg->enabled == NULL || *(method->cfg->enabled) == 0) { 498 debug3_f("method %s not enabled", name); 499 return NULL; 500 } 501 if (!auth2_method_allowed(authctxt, method->cfg->name, NULL)) { 502 debug3_f("method %s not allowed " 503 "by AuthenticationMethods", name); 504 return NULL; 505 } 506 return method; 507} 508 509/* 510 * Prune the AuthenticationMethods supplied in the configuration, removing 511 * any methods lists that include disabled methods. Note that this might 512 * leave authctxt->num_auth_methods == 0, even when multiple required auth 513 * has been requested. For this reason, all tests for whether multiple is 514 * enabled should consult options.num_auth_methods directly. 515 */ 516int 517auth2_setup_methods_lists(Authctxt *authctxt) 518{ 519 u_int i; 520 521 /* First, normalise away the "any" pseudo-method */ 522 if (options.num_auth_methods == 1 && 523 strcmp(options.auth_methods[0], "any") == 0) { 524 free(options.auth_methods[0]); 525 options.auth_methods[0] = NULL; 526 options.num_auth_methods = 0; 527 } 528 529 if (options.num_auth_methods == 0) 530 return 0; 531 debug3_f("checking methods"); 532 authctxt->auth_methods = xcalloc(options.num_auth_methods, 533 sizeof(*authctxt->auth_methods)); 534 authctxt->num_auth_methods = 0; 535 for (i = 0; i < options.num_auth_methods; i++) { 536 if (auth2_methods_valid(options.auth_methods[i], 1) != 0) { 537 logit("Authentication methods list \"%s\" contains " 538 "disabled method, skipping", 539 options.auth_methods[i]); 540 continue; 541 } 542 debug("authentication methods list %d: %s", 543 authctxt->num_auth_methods, options.auth_methods[i]); 544 authctxt->auth_methods[authctxt->num_auth_methods++] = 545 xstrdup(options.auth_methods[i]); 546 } 547 if (authctxt->num_auth_methods == 0) { 548 error("No AuthenticationMethods left after eliminating " 549 "disabled methods"); 550 return -1; 551 } 552 return 0; 553} 554 555static int 556list_starts_with(const char *methods, const char *method, 557 const char *submethod) 558{ 559 size_t l = strlen(method); 560 int match; 561 const char *p; 562 563 if (strncmp(methods, method, l) != 0) 564 return MATCH_NONE; 565 p = methods + l; 566 match = MATCH_METHOD; 567 if (*p == ':') { 568 if (!submethod) 569 return MATCH_PARTIAL; 570 l = strlen(submethod); 571 p += 1; 572 if (strncmp(submethod, p, l)) 573 return MATCH_NONE; 574 p += l; 575 match = MATCH_BOTH; 576 } 577 if (*p != ',' && *p != '\0') 578 return MATCH_NONE; 579 return match; 580} 581 582/* 583 * Remove method from the start of a comma-separated list of methods. 584 * Returns 0 if the list of methods did not start with that method or 1 585 * if it did. 586 */ 587static int 588remove_method(char **methods, const char *method, const char *submethod) 589{ 590 char *omethods = *methods, *p; 591 size_t l = strlen(method); 592 int match; 593 594 match = list_starts_with(omethods, method, submethod); 595 if (match != MATCH_METHOD && match != MATCH_BOTH) 596 return 0; 597 p = omethods + l; 598 if (submethod && match == MATCH_BOTH) 599 p += 1 + strlen(submethod); /* include colon */ 600 if (*p == ',') 601 p++; 602 *methods = xstrdup(p); 603 free(omethods); 604 return 1; 605} 606 607/* 608 * Called after successful authentication. Will remove the successful method 609 * from the start of each list in which it occurs. If it was the last method 610 * in any list, then authentication is deemed successful. 611 * Returns 1 if the method completed any authentication list or 0 otherwise. 612 */ 613int 614auth2_update_methods_lists(Authctxt *authctxt, const char *method, 615 const char *submethod) 616{ 617 u_int i, found = 0; 618 619 debug3_f("updating methods list after \"%s\"", method); 620 for (i = 0; i < authctxt->num_auth_methods; i++) { 621 if (!remove_method(&(authctxt->auth_methods[i]), method, 622 submethod)) 623 continue; 624 found = 1; 625 if (*authctxt->auth_methods[i] == '\0') { 626 debug2("authentication methods list %d complete", i); 627 return 1; 628 } 629 debug3("authentication methods list %d remaining: \"%s\"", 630 i, authctxt->auth_methods[i]); 631 } 632 /* This should not happen, but would be bad if it did */ 633 if (!found) 634 fatal_f("method not in AuthenticationMethods"); 635 return 0; 636} 637 638/* Reset method-specific information */ 639void auth2_authctxt_reset_info(Authctxt *authctxt) 640{ 641 sshkey_free(authctxt->auth_method_key); 642 free(authctxt->auth_method_info); 643 authctxt->auth_method_key = NULL; 644 authctxt->auth_method_info = NULL; 645} 646 647/* Record auth method-specific information for logs */ 648void 649auth2_record_info(Authctxt *authctxt, const char *fmt, ...) 650{ 651 va_list ap; 652 int i; 653 654 free(authctxt->auth_method_info); 655 authctxt->auth_method_info = NULL; 656 657 va_start(ap, fmt); 658 i = vasprintf(&authctxt->auth_method_info, fmt, ap); 659 va_end(ap); 660 661 if (i == -1) 662 fatal_f("vasprintf failed"); 663} 664 665/* 666 * Records a public key used in authentication. This is used for logging 667 * and to ensure that the same key is not subsequently accepted again for 668 * multiple authentication. 669 */ 670void 671auth2_record_key(Authctxt *authctxt, int authenticated, 672 const struct sshkey *key) 673{ 674 struct sshkey **tmp, *dup; 675 int r; 676 677 if ((r = sshkey_from_private(key, &dup)) != 0) 678 fatal_fr(r, "copy key"); 679 sshkey_free(authctxt->auth_method_key); 680 authctxt->auth_method_key = dup; 681 682 if (!authenticated) 683 return; 684 685 /* If authenticated, make sure we don't accept this key again */ 686 if ((r = sshkey_from_private(key, &dup)) != 0) 687 fatal_fr(r, "copy key"); 688 if (authctxt->nprev_keys >= INT_MAX || 689 (tmp = recallocarray(authctxt->prev_keys, authctxt->nprev_keys, 690 authctxt->nprev_keys + 1, sizeof(*authctxt->prev_keys))) == NULL) 691 fatal_f("reallocarray failed"); 692 authctxt->prev_keys = tmp; 693 authctxt->prev_keys[authctxt->nprev_keys] = dup; 694 authctxt->nprev_keys++; 695 696} 697 698/* Checks whether a key has already been previously used for authentication */ 699int 700auth2_key_already_used(Authctxt *authctxt, const struct sshkey *key) 701{ 702 u_int i; 703 char *fp; 704 705 for (i = 0; i < authctxt->nprev_keys; i++) { 706 if (sshkey_equal_public(key, authctxt->prev_keys[i])) { 707 fp = sshkey_fingerprint(authctxt->prev_keys[i], 708 options.fingerprint_hash, SSH_FP_DEFAULT); 709 debug3_f("key already used: %s %s", 710 sshkey_type(authctxt->prev_keys[i]), 711 fp == NULL ? "UNKNOWN" : fp); 712 free(fp); 713 return 1; 714 } 715 } 716 return 0; 717} 718 719/* 720 * Updates authctxt->session_info with details of authentication. Should be 721 * whenever an authentication method succeeds. 722 */ 723void 724auth2_update_session_info(Authctxt *authctxt, const char *method, 725 const char *submethod) 726{ 727 int r; 728 729 if (authctxt->session_info == NULL) { 730 if ((authctxt->session_info = sshbuf_new()) == NULL) 731 fatal_f("sshbuf_new"); 732 } 733 734 /* Append method[/submethod] */ 735 if ((r = sshbuf_putf(authctxt->session_info, "%s%s%s", 736 method, submethod == NULL ? "" : "/", 737 submethod == NULL ? "" : submethod)) != 0) 738 fatal_fr(r, "append method"); 739 740 /* Append key if present */ 741 if (authctxt->auth_method_key != NULL) { 742 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 743 (r = sshkey_format_text(authctxt->auth_method_key, 744 authctxt->session_info)) != 0) 745 fatal_fr(r, "append key"); 746 } 747 748 if (authctxt->auth_method_info != NULL) { 749 /* Ensure no ambiguity here */ 750 if (strchr(authctxt->auth_method_info, '\n') != NULL) 751 fatal_f("auth_method_info contains \\n"); 752 if ((r = sshbuf_put_u8(authctxt->session_info, ' ')) != 0 || 753 (r = sshbuf_putf(authctxt->session_info, "%s", 754 authctxt->auth_method_info)) != 0) { 755 fatal_fr(r, "append method info"); 756 } 757 } 758 if ((r = sshbuf_put_u8(authctxt->session_info, '\n')) != 0) 759 fatal_fr(r, "append"); 760} 761 762