1 /* $OpenBSD: auth.c,v 1.115 2016/06/15 00:40:40 dtucker Exp $ */ 2 /* 3 * Copyright (c) 2000 Markus Friedl. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26 #include "includes.h" 27 28 #include <sys/types.h> 29 #include <sys/stat.h> 30 #include <sys/socket.h> 31 32 #include <netinet/in.h> 33 34 #include <errno.h> 35 #include <fcntl.h> 36 #ifdef HAVE_PATHS_H 37 # include <paths.h> 38 #endif 39 #include <pwd.h> 40 #ifdef HAVE_LOGIN_H 41 #include <login.h> 42 #endif 43 #ifdef USE_SHADOW 44 #include <shadow.h> 45 #endif 46 #ifdef HAVE_LIBGEN_H 47 #include <libgen.h> 48 #endif 49 #include <stdarg.h> 50 #include <stdio.h> 51 #include <string.h> 52 #include <unistd.h> 53 #include <limits.h> 54 #include <netdb.h> 55 56 #include "xmalloc.h" 57 #include "match.h" 58 #include "groupaccess.h" 59 #include "log.h" 60 #include "buffer.h" 61 #include "misc.h" 62 #include "servconf.h" 63 #include "key.h" 64 #include "hostfile.h" 65 #include "auth.h" 66 #include "auth-options.h" 67 #include "canohost.h" 68 #include "uidswap.h" 69 #include "packet.h" 70 #include "loginrec.h" 71 #ifdef GSSAPI 72 #include "ssh-gss.h" 73 #endif 74 #include "authfile.h" 75 #include "monitor_wrap.h" 76 #include "authfile.h" 77 #include "ssherr.h" 78 #include "compat.h" 79 80 /* import */ 81 extern ServerOptions options; 82 extern int use_privsep; 83 extern Buffer loginmsg; 84 extern struct passwd *privsep_pw; 85 86 /* Debugging messages */ 87 Buffer auth_debug; 88 int auth_debug_init; 89 90 /* 91 * Check if the user is allowed to log in via ssh. If user is listed 92 * in DenyUsers or one of user's groups is listed in DenyGroups, false 93 * will be returned. If AllowUsers isn't empty and user isn't listed 94 * there, or if AllowGroups isn't empty and one of user's groups isn't 95 * listed there, false will be returned. 96 * If the user's shell is not executable, false will be returned. 97 * Otherwise true is returned. 98 */ 99 int 100 allowed_user(struct passwd * pw) 101 { 102 struct ssh *ssh = active_state; /* XXX */ 103 struct stat st; 104 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL; 105 u_int i; 106 #ifdef USE_SHADOW 107 struct spwd *spw = NULL; 108 #endif 109 110 /* Shouldn't be called if pw is NULL, but better safe than sorry... */ 111 if (!pw || !pw->pw_name) 112 return 0; 113 114 #ifdef USE_SHADOW 115 if (!options.use_pam) 116 spw = getspnam(pw->pw_name); 117 #ifdef HAS_SHADOW_EXPIRE 118 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw)) 119 return 0; 120 #endif /* HAS_SHADOW_EXPIRE */ 121 #endif /* USE_SHADOW */ 122 123 /* grab passwd field for locked account check */ 124 passwd = pw->pw_passwd; 125 #ifdef USE_SHADOW 126 if (spw != NULL) 127 #ifdef USE_LIBIAF 128 passwd = get_iaf_password(pw); 129 #else 130 passwd = spw->sp_pwdp; 131 #endif /* USE_LIBIAF */ 132 #endif 133 134 /* check for locked account */ 135 if (!options.use_pam && passwd && *passwd) { 136 int locked = 0; 137 138 #ifdef LOCKED_PASSWD_STRING 139 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0) 140 locked = 1; 141 #endif 142 #ifdef LOCKED_PASSWD_PREFIX 143 if (strncmp(passwd, LOCKED_PASSWD_PREFIX, 144 strlen(LOCKED_PASSWD_PREFIX)) == 0) 145 locked = 1; 146 #endif 147 #ifdef LOCKED_PASSWD_SUBSTR 148 if (strstr(passwd, LOCKED_PASSWD_SUBSTR)) 149 locked = 1; 150 #endif 151 #ifdef USE_LIBIAF 152 free((void *) passwd); 153 #endif /* USE_LIBIAF */ 154 if (locked) { 155 logit("User %.100s not allowed because account is locked", 156 pw->pw_name); 157 return 0; 158 } 159 } 160 161 /* 162 * Deny if shell does not exist or is not executable unless we 163 * are chrooting. 164 */ 165 if (options.chroot_directory == NULL || 166 strcasecmp(options.chroot_directory, "none") == 0) { 167 char *shell = xstrdup((pw->pw_shell[0] == '\0') ? 168 _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */ 169 170 if (stat(shell, &st) != 0) { 171 logit("User %.100s not allowed because shell %.100s " 172 "does not exist", pw->pw_name, shell); 173 free(shell); 174 return 0; 175 } 176 if (S_ISREG(st.st_mode) == 0 || 177 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) { 178 logit("User %.100s not allowed because shell %.100s " 179 "is not executable", pw->pw_name, shell); 180 free(shell); 181 return 0; 182 } 183 free(shell); 184 } 185 186 if (options.num_deny_users > 0 || options.num_allow_users > 0 || 187 options.num_deny_groups > 0 || options.num_allow_groups > 0) { 188 hostname = auth_get_canonical_hostname(ssh, options.use_dns); 189 ipaddr = ssh_remote_ipaddr(ssh); 190 } 191 192 /* Return false if user is listed in DenyUsers */ 193 if (options.num_deny_users > 0) { 194 for (i = 0; i < options.num_deny_users; i++) 195 if (match_user(pw->pw_name, hostname, ipaddr, 196 options.deny_users[i])) { 197 logit("User %.100s from %.100s not allowed " 198 "because listed in DenyUsers", 199 pw->pw_name, hostname); 200 return 0; 201 } 202 } 203 /* Return false if AllowUsers isn't empty and user isn't listed there */ 204 if (options.num_allow_users > 0) { 205 for (i = 0; i < options.num_allow_users; i++) 206 if (match_user(pw->pw_name, hostname, ipaddr, 207 options.allow_users[i])) 208 break; 209 /* i < options.num_allow_users iff we break for loop */ 210 if (i >= options.num_allow_users) { 211 logit("User %.100s from %.100s not allowed because " 212 "not listed in AllowUsers", pw->pw_name, hostname); 213 return 0; 214 } 215 } 216 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { 217 /* Get the user's group access list (primary and supplementary) */ 218 if (ga_init(pw->pw_name, pw->pw_gid) == 0) { 219 logit("User %.100s from %.100s not allowed because " 220 "not in any group", pw->pw_name, hostname); 221 return 0; 222 } 223 224 /* Return false if one of user's groups is listed in DenyGroups */ 225 if (options.num_deny_groups > 0) 226 if (ga_match(options.deny_groups, 227 options.num_deny_groups)) { 228 ga_free(); 229 logit("User %.100s from %.100s not allowed " 230 "because a group is listed in DenyGroups", 231 pw->pw_name, hostname); 232 return 0; 233 } 234 /* 235 * Return false if AllowGroups isn't empty and one of user's groups 236 * isn't listed there 237 */ 238 if (options.num_allow_groups > 0) 239 if (!ga_match(options.allow_groups, 240 options.num_allow_groups)) { 241 ga_free(); 242 logit("User %.100s from %.100s not allowed " 243 "because none of user's groups are listed " 244 "in AllowGroups", pw->pw_name, hostname); 245 return 0; 246 } 247 ga_free(); 248 } 249 250 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER 251 if (!sys_auth_allowed_user(pw, &loginmsg)) 252 return 0; 253 #endif 254 255 /* We found no reason not to let this user try to log on... */ 256 return 1; 257 } 258 259 void 260 auth_info(Authctxt *authctxt, const char *fmt, ...) 261 { 262 va_list ap; 263 int i; 264 265 free(authctxt->info); 266 authctxt->info = NULL; 267 268 va_start(ap, fmt); 269 i = vasprintf(&authctxt->info, fmt, ap); 270 va_end(ap); 271 272 if (i < 0 || authctxt->info == NULL) 273 fatal("vasprintf failed"); 274 } 275 276 void 277 auth_log(Authctxt *authctxt, int authenticated, int partial, 278 const char *method, const char *submethod) 279 { 280 struct ssh *ssh = active_state; /* XXX */ 281 void (*authlog) (const char *fmt,...) = verbose; 282 char *authmsg; 283 284 if (use_privsep && !mm_is_monitor() && !authctxt->postponed) 285 return; 286 287 /* Raise logging level */ 288 if (authenticated == 1 || 289 !authctxt->valid || 290 authctxt->failures >= options.max_authtries / 2 || 291 strcmp(method, "password") == 0) 292 authlog = logit; 293 294 if (authctxt->postponed) 295 authmsg = "Postponed"; 296 else if (partial) 297 authmsg = "Partial"; 298 else 299 authmsg = authenticated ? "Accepted" : "Failed"; 300 301 authlog("%s %s%s%s for %s%.100s from %.200s port %d %s%s%s", 302 authmsg, 303 method, 304 submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod, 305 authctxt->valid ? "" : "invalid user ", 306 authctxt->user, 307 ssh_remote_ipaddr(ssh), 308 ssh_remote_port(ssh), 309 compat20 ? "ssh2" : "ssh1", 310 authctxt->info != NULL ? ": " : "", 311 authctxt->info != NULL ? authctxt->info : ""); 312 free(authctxt->info); 313 authctxt->info = NULL; 314 315 #ifdef CUSTOM_FAILED_LOGIN 316 if (authenticated == 0 && !authctxt->postponed && 317 (strcmp(method, "password") == 0 || 318 strncmp(method, "keyboard-interactive", 20) == 0 || 319 strcmp(method, "challenge-response") == 0)) 320 record_failed_login(authctxt->user, 321 auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); 322 # ifdef WITH_AIXAUTHENTICATE 323 if (authenticated) 324 sys_auth_record_login(authctxt->user, 325 auth_get_canonical_hostname(ssh, options.use_dns), "ssh", 326 &loginmsg); 327 # endif 328 #endif 329 #ifdef SSH_AUDIT_EVENTS 330 if (authenticated == 0 && !authctxt->postponed) 331 audit_event(audit_classify_auth(method)); 332 #endif 333 } 334 335 336 void 337 auth_maxtries_exceeded(Authctxt *authctxt) 338 { 339 struct ssh *ssh = active_state; /* XXX */ 340 341 error("maximum authentication attempts exceeded for " 342 "%s%.100s from %.200s port %d %s", 343 authctxt->valid ? "" : "invalid user ", 344 authctxt->user, 345 ssh_remote_ipaddr(ssh), 346 ssh_remote_port(ssh), 347 compat20 ? "ssh2" : "ssh1"); 348 packet_disconnect("Too many authentication failures"); 349 /* NOTREACHED */ 350 } 351 352 /* 353 * Check whether root logins are disallowed. 354 */ 355 int 356 auth_root_allowed(const char *method) 357 { 358 struct ssh *ssh = active_state; /* XXX */ 359 360 switch (options.permit_root_login) { 361 case PERMIT_YES: 362 return 1; 363 case PERMIT_NO_PASSWD: 364 if (strcmp(method, "publickey") == 0 || 365 strcmp(method, "hostbased") == 0 || 366 strcmp(method, "gssapi-with-mic") == 0) 367 return 1; 368 break; 369 case PERMIT_FORCED_ONLY: 370 if (forced_command) { 371 logit("Root login accepted for forced command."); 372 return 1; 373 } 374 break; 375 } 376 logit("ROOT LOGIN REFUSED FROM %.200s port %d", 377 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 378 return 0; 379 } 380 381 382 /* 383 * Given a template and a passwd structure, build a filename 384 * by substituting % tokenised options. Currently, %% becomes '%', 385 * %h becomes the home directory and %u the username. 386 * 387 * This returns a buffer allocated by xmalloc. 388 */ 389 char * 390 expand_authorized_keys(const char *filename, struct passwd *pw) 391 { 392 char *file, ret[PATH_MAX]; 393 int i; 394 395 file = percent_expand(filename, "h", pw->pw_dir, 396 "u", pw->pw_name, (char *)NULL); 397 398 /* 399 * Ensure that filename starts anchored. If not, be backward 400 * compatible and prepend the '%h/' 401 */ 402 if (*file == '/') 403 return (file); 404 405 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file); 406 if (i < 0 || (size_t)i >= sizeof(ret)) 407 fatal("expand_authorized_keys: path too long"); 408 free(file); 409 return (xstrdup(ret)); 410 } 411 412 char * 413 authorized_principals_file(struct passwd *pw) 414 { 415 if (options.authorized_principals_file == NULL) 416 return NULL; 417 return expand_authorized_keys(options.authorized_principals_file, pw); 418 } 419 420 /* return ok if key exists in sysfile or userfile */ 421 HostStatus 422 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host, 423 const char *sysfile, const char *userfile) 424 { 425 char *user_hostfile; 426 struct stat st; 427 HostStatus host_status; 428 struct hostkeys *hostkeys; 429 const struct hostkey_entry *found; 430 431 hostkeys = init_hostkeys(); 432 load_hostkeys(hostkeys, host, sysfile); 433 if (userfile != NULL) { 434 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid); 435 if (options.strict_modes && 436 (stat(user_hostfile, &st) == 0) && 437 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || 438 (st.st_mode & 022) != 0)) { 439 logit("Authentication refused for %.100s: " 440 "bad owner or modes for %.200s", 441 pw->pw_name, user_hostfile); 442 auth_debug_add("Ignored %.200s: bad ownership or modes", 443 user_hostfile); 444 } else { 445 temporarily_use_uid(pw); 446 load_hostkeys(hostkeys, host, user_hostfile); 447 restore_uid(); 448 } 449 free(user_hostfile); 450 } 451 host_status = check_key_in_hostkeys(hostkeys, key, &found); 452 if (host_status == HOST_REVOKED) 453 error("WARNING: revoked key for %s attempted authentication", 454 found->host); 455 else if (host_status == HOST_OK) 456 debug("%s: key for %s found at %s:%ld", __func__, 457 found->host, found->file, found->line); 458 else 459 debug("%s: key for host %s not found", __func__, host); 460 461 free_hostkeys(hostkeys); 462 463 return host_status; 464 } 465 466 /* 467 * Check a given path for security. This is defined as all components 468 * of the path to the file must be owned by either the owner of 469 * of the file or root and no directories must be group or world writable. 470 * 471 * XXX Should any specific check be done for sym links ? 472 * 473 * Takes a file name, its stat information (preferably from fstat() to 474 * avoid races), the uid of the expected owner, their home directory and an 475 * error buffer plus max size as arguments. 476 * 477 * Returns 0 on success and -1 on failure 478 */ 479 int 480 auth_secure_path(const char *name, struct stat *stp, const char *pw_dir, 481 uid_t uid, char *err, size_t errlen) 482 { 483 char buf[PATH_MAX], homedir[PATH_MAX]; 484 char *cp; 485 int comparehome = 0; 486 struct stat st; 487 488 if (realpath(name, buf) == NULL) { 489 snprintf(err, errlen, "realpath %s failed: %s", name, 490 strerror(errno)); 491 return -1; 492 } 493 if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL) 494 comparehome = 1; 495 496 if (!S_ISREG(stp->st_mode)) { 497 snprintf(err, errlen, "%s is not a regular file", buf); 498 return -1; 499 } 500 if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) || 501 (stp->st_mode & 022) != 0) { 502 snprintf(err, errlen, "bad ownership or modes for file %s", 503 buf); 504 return -1; 505 } 506 507 /* for each component of the canonical path, walking upwards */ 508 for (;;) { 509 if ((cp = dirname(buf)) == NULL) { 510 snprintf(err, errlen, "dirname() failed"); 511 return -1; 512 } 513 strlcpy(buf, cp, sizeof(buf)); 514 515 if (stat(buf, &st) < 0 || 516 (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) || 517 (st.st_mode & 022) != 0) { 518 snprintf(err, errlen, 519 "bad ownership or modes for directory %s", buf); 520 return -1; 521 } 522 523 /* If are past the homedir then we can stop */ 524 if (comparehome && strcmp(homedir, buf) == 0) 525 break; 526 527 /* 528 * dirname should always complete with a "/" path, 529 * but we can be paranoid and check for "." too 530 */ 531 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0)) 532 break; 533 } 534 return 0; 535 } 536 537 /* 538 * Version of secure_path() that accepts an open file descriptor to 539 * avoid races. 540 * 541 * Returns 0 on success and -1 on failure 542 */ 543 static int 544 secure_filename(FILE *f, const char *file, struct passwd *pw, 545 char *err, size_t errlen) 546 { 547 struct stat st; 548 549 /* check the open file to avoid races */ 550 if (fstat(fileno(f), &st) < 0) { 551 snprintf(err, errlen, "cannot stat file %s: %s", 552 file, strerror(errno)); 553 return -1; 554 } 555 return auth_secure_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen); 556 } 557 558 static FILE * 559 auth_openfile(const char *file, struct passwd *pw, int strict_modes, 560 int log_missing, char *file_type) 561 { 562 char line[1024]; 563 struct stat st; 564 int fd; 565 FILE *f; 566 567 if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) { 568 if (log_missing || errno != ENOENT) 569 debug("Could not open %s '%s': %s", file_type, file, 570 strerror(errno)); 571 return NULL; 572 } 573 574 if (fstat(fd, &st) < 0) { 575 close(fd); 576 return NULL; 577 } 578 if (!S_ISREG(st.st_mode)) { 579 logit("User %s %s %s is not a regular file", 580 pw->pw_name, file_type, file); 581 close(fd); 582 return NULL; 583 } 584 unset_nonblock(fd); 585 if ((f = fdopen(fd, "r")) == NULL) { 586 close(fd); 587 return NULL; 588 } 589 if (strict_modes && 590 secure_filename(f, file, pw, line, sizeof(line)) != 0) { 591 fclose(f); 592 logit("Authentication refused: %s", line); 593 auth_debug_add("Ignored %s: %s", file_type, line); 594 return NULL; 595 } 596 597 return f; 598 } 599 600 601 FILE * 602 auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes) 603 { 604 return auth_openfile(file, pw, strict_modes, 1, "authorized keys"); 605 } 606 607 FILE * 608 auth_openprincipals(const char *file, struct passwd *pw, int strict_modes) 609 { 610 return auth_openfile(file, pw, strict_modes, 0, 611 "authorized principals"); 612 } 613 614 struct passwd * 615 getpwnamallow(const char *user) 616 { 617 struct ssh *ssh = active_state; /* XXX */ 618 #ifdef HAVE_LOGIN_CAP 619 extern login_cap_t *lc; 620 #ifdef BSD_AUTH 621 auth_session_t *as; 622 #endif 623 #endif 624 struct passwd *pw; 625 struct connection_info *ci = get_connection_info(1, options.use_dns); 626 627 ci->user = user; 628 parse_server_match_config(&options, ci); 629 630 #if defined(_AIX) && defined(HAVE_SETAUTHDB) 631 aix_setauthdb(user); 632 #endif 633 634 pw = getpwnam(user); 635 636 #if defined(_AIX) && defined(HAVE_SETAUTHDB) 637 aix_restoreauthdb(); 638 #endif 639 #ifdef HAVE_CYGWIN 640 /* 641 * Windows usernames are case-insensitive. To avoid later problems 642 * when trying to match the username, the user is only allowed to 643 * login if the username is given in the same case as stored in the 644 * user database. 645 */ 646 if (pw != NULL && strcmp(user, pw->pw_name) != 0) { 647 logit("Login name %.100s does not match stored username %.100s", 648 user, pw->pw_name); 649 pw = NULL; 650 } 651 #endif 652 if (pw == NULL) { 653 logit("Invalid user %.100s from %.100s port %d", 654 user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 655 #ifdef CUSTOM_FAILED_LOGIN 656 record_failed_login(user, 657 auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); 658 #endif 659 #ifdef SSH_AUDIT_EVENTS 660 audit_event(SSH_INVALID_USER); 661 #endif /* SSH_AUDIT_EVENTS */ 662 return (NULL); 663 } 664 if (!allowed_user(pw)) 665 return (NULL); 666 #ifdef HAVE_LOGIN_CAP 667 if ((lc = login_getclass(pw->pw_class)) == NULL) { 668 debug("unable to get login class: %s", user); 669 return (NULL); 670 } 671 #ifdef BSD_AUTH 672 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 || 673 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) { 674 debug("Approval failure for %s", user); 675 pw = NULL; 676 } 677 if (as != NULL) 678 auth_close(as); 679 #endif 680 #endif 681 if (pw != NULL) 682 return (pwcopy(pw)); 683 return (NULL); 684 } 685 686 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */ 687 int 688 auth_key_is_revoked(Key *key) 689 { 690 char *fp = NULL; 691 int r; 692 693 if (options.revoked_keys_file == NULL) 694 return 0; 695 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 696 SSH_FP_DEFAULT)) == NULL) { 697 r = SSH_ERR_ALLOC_FAIL; 698 error("%s: fingerprint key: %s", __func__, ssh_err(r)); 699 goto out; 700 } 701 702 r = sshkey_check_revoked(key, options.revoked_keys_file); 703 switch (r) { 704 case 0: 705 break; /* not revoked */ 706 case SSH_ERR_KEY_REVOKED: 707 error("Authentication key %s %s revoked by file %s", 708 sshkey_type(key), fp, options.revoked_keys_file); 709 goto out; 710 default: 711 error("Error checking authentication key %s %s in " 712 "revoked keys file %s: %s", sshkey_type(key), fp, 713 options.revoked_keys_file, ssh_err(r)); 714 goto out; 715 } 716 717 /* Success */ 718 r = 0; 719 720 out: 721 free(fp); 722 return r == 0 ? 0 : 1; 723 } 724 725 void 726 auth_debug_add(const char *fmt,...) 727 { 728 char buf[1024]; 729 va_list args; 730 731 if (!auth_debug_init) 732 return; 733 734 va_start(args, fmt); 735 vsnprintf(buf, sizeof(buf), fmt, args); 736 va_end(args); 737 buffer_put_cstring(&auth_debug, buf); 738 } 739 740 void 741 auth_debug_send(void) 742 { 743 char *msg; 744 745 if (!auth_debug_init) 746 return; 747 while (buffer_len(&auth_debug)) { 748 msg = buffer_get_string(&auth_debug, NULL); 749 packet_send_debug("%s", msg); 750 free(msg); 751 } 752 } 753 754 void 755 auth_debug_reset(void) 756 { 757 if (auth_debug_init) 758 buffer_clear(&auth_debug); 759 else { 760 buffer_init(&auth_debug); 761 auth_debug_init = 1; 762 } 763 } 764 765 struct passwd * 766 fakepw(void) 767 { 768 static struct passwd fake; 769 770 memset(&fake, 0, sizeof(fake)); 771 fake.pw_name = "NOUSER"; 772 fake.pw_passwd = 773 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK"; 774 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS 775 fake.pw_gecos = "NOUSER"; 776 #endif 777 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid; 778 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid; 779 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS 780 fake.pw_class = ""; 781 #endif 782 fake.pw_dir = "/nonexist"; 783 fake.pw_shell = "/nonexist"; 784 785 return (&fake); 786 } 787 788 /* 789 * Returns the remote DNS hostname as a string. The returned string must not 790 * be freed. NB. this will usually trigger a DNS query the first time it is 791 * called. 792 * This function does additional checks on the hostname to mitigate some 793 * attacks on legacy rhosts-style authentication. 794 * XXX is RhostsRSAAuthentication vulnerable to these? 795 * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?) 796 */ 797 798 static char * 799 remote_hostname(struct ssh *ssh) 800 { 801 struct sockaddr_storage from; 802 socklen_t fromlen; 803 struct addrinfo hints, *ai, *aitop; 804 char name[NI_MAXHOST], ntop2[NI_MAXHOST]; 805 const char *ntop = ssh_remote_ipaddr(ssh); 806 807 /* Get IP address of client. */ 808 fromlen = sizeof(from); 809 memset(&from, 0, sizeof(from)); 810 if (getpeername(ssh_packet_get_connection_in(ssh), 811 (struct sockaddr *)&from, &fromlen) < 0) { 812 debug("getpeername failed: %.100s", strerror(errno)); 813 return strdup(ntop); 814 } 815 816 ipv64_normalise_mapped(&from, &fromlen); 817 if (from.ss_family == AF_INET6) 818 fromlen = sizeof(struct sockaddr_in6); 819 820 debug3("Trying to reverse map address %.100s.", ntop); 821 /* Map the IP address to a host name. */ 822 if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), 823 NULL, 0, NI_NAMEREQD) != 0) { 824 /* Host name not found. Use ip address. */ 825 return strdup(ntop); 826 } 827 828 /* 829 * if reverse lookup result looks like a numeric hostname, 830 * someone is trying to trick us by PTR record like following: 831 * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 832 */ 833 memset(&hints, 0, sizeof(hints)); 834 hints.ai_socktype = SOCK_DGRAM; /*dummy*/ 835 hints.ai_flags = AI_NUMERICHOST; 836 if (getaddrinfo(name, NULL, &hints, &ai) == 0) { 837 logit("Nasty PTR record \"%s\" is set up for %s, ignoring", 838 name, ntop); 839 freeaddrinfo(ai); 840 return strdup(ntop); 841 } 842 843 /* Names are stored in lowercase. */ 844 lowercase(name); 845 846 /* 847 * Map it back to an IP address and check that the given 848 * address actually is an address of this host. This is 849 * necessary because anyone with access to a name server can 850 * define arbitrary names for an IP address. Mapping from 851 * name to IP address can be trusted better (but can still be 852 * fooled if the intruder has access to the name server of 853 * the domain). 854 */ 855 memset(&hints, 0, sizeof(hints)); 856 hints.ai_family = from.ss_family; 857 hints.ai_socktype = SOCK_STREAM; 858 if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { 859 logit("reverse mapping checking getaddrinfo for %.700s " 860 "[%s] failed.", name, ntop); 861 return strdup(ntop); 862 } 863 /* Look for the address from the list of addresses. */ 864 for (ai = aitop; ai; ai = ai->ai_next) { 865 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, 866 sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && 867 (strcmp(ntop, ntop2) == 0)) 868 break; 869 } 870 freeaddrinfo(aitop); 871 /* If we reached the end of the list, the address was not there. */ 872 if (ai == NULL) { 873 /* Address not found for the host name. */ 874 logit("Address %.100s maps to %.600s, but this does not " 875 "map back to the address.", ntop, name); 876 return strdup(ntop); 877 } 878 return strdup(name); 879 } 880 881 /* 882 * Return the canonical name of the host in the other side of the current 883 * connection. The host name is cached, so it is efficient to call this 884 * several times. 885 */ 886 887 const char * 888 auth_get_canonical_hostname(struct ssh *ssh, int use_dns) 889 { 890 static char *dnsname; 891 892 if (!use_dns) 893 return ssh_remote_ipaddr(ssh); 894 else if (dnsname != NULL) 895 return dnsname; 896 else { 897 dnsname = remote_hostname(ssh); 898 return dnsname; 899 } 900 } 901