1 /* $OpenBSD: auth.c,v 1.119 2016/12/15 21:29:05 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 __RCSID("$FreeBSD$"); 28 29 #include <sys/types.h> 30 #include <sys/stat.h> 31 #include <sys/socket.h> 32 33 #include <netinet/in.h> 34 35 #include <errno.h> 36 #include <fcntl.h> 37 #ifdef HAVE_PATHS_H 38 # include <paths.h> 39 #endif 40 #include <pwd.h> 41 #ifdef HAVE_LOGIN_H 42 #include <login.h> 43 #endif 44 #ifdef USE_SHADOW 45 #include <shadow.h> 46 #endif 47 #ifdef HAVE_LIBGEN_H 48 #include <libgen.h> 49 #endif 50 #include <stdarg.h> 51 #include <stdio.h> 52 #include <string.h> 53 #include <unistd.h> 54 #include <limits.h> 55 #include <netdb.h> 56 57 #include "xmalloc.h" 58 #include "match.h" 59 #include "groupaccess.h" 60 #include "log.h" 61 #include "buffer.h" 62 #include "misc.h" 63 #include "servconf.h" 64 #include "key.h" 65 #include "hostfile.h" 66 #include "auth.h" 67 #include "auth-options.h" 68 #include "canohost.h" 69 #include "uidswap.h" 70 #include "packet.h" 71 #include "loginrec.h" 72 #ifdef GSSAPI 73 #include "ssh-gss.h" 74 #endif 75 #include "authfile.h" 76 #include "monitor_wrap.h" 77 #include "authfile.h" 78 #include "ssherr.h" 79 #include "compat.h" 80 #include "blacklist_client.h" 81 82 /* import */ 83 extern ServerOptions options; 84 extern int use_privsep; 85 extern Buffer loginmsg; 86 extern struct passwd *privsep_pw; 87 88 /* Debugging messages */ 89 Buffer auth_debug; 90 int auth_debug_init; 91 92 /* 93 * Check if the user is allowed to log in via ssh. If user is listed 94 * in DenyUsers or one of user's groups is listed in DenyGroups, false 95 * will be returned. If AllowUsers isn't empty and user isn't listed 96 * there, or if AllowGroups isn't empty and one of user's groups isn't 97 * listed there, false will be returned. 98 * If the user's shell is not executable, false will be returned. 99 * Otherwise true is returned. 100 */ 101 int 102 allowed_user(struct passwd * pw) 103 { 104 struct ssh *ssh = active_state; /* XXX */ 105 struct stat st; 106 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL; 107 u_int i; 108 int r; 109 #ifdef USE_SHADOW 110 struct spwd *spw = NULL; 111 #endif 112 113 /* Shouldn't be called if pw is NULL, but better safe than sorry... */ 114 if (!pw || !pw->pw_name) 115 return 0; 116 117 #ifdef USE_SHADOW 118 if (!options.use_pam) 119 spw = getspnam(pw->pw_name); 120 #ifdef HAS_SHADOW_EXPIRE 121 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw)) 122 return 0; 123 #endif /* HAS_SHADOW_EXPIRE */ 124 #endif /* USE_SHADOW */ 125 126 /* grab passwd field for locked account check */ 127 passwd = pw->pw_passwd; 128 #ifdef USE_SHADOW 129 if (spw != NULL) 130 #ifdef USE_LIBIAF 131 passwd = get_iaf_password(pw); 132 #else 133 passwd = spw->sp_pwdp; 134 #endif /* USE_LIBIAF */ 135 #endif 136 137 /* check for locked account */ 138 if (!options.use_pam && passwd && *passwd) { 139 int locked = 0; 140 141 #ifdef LOCKED_PASSWD_STRING 142 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0) 143 locked = 1; 144 #endif 145 #ifdef LOCKED_PASSWD_PREFIX 146 if (strncmp(passwd, LOCKED_PASSWD_PREFIX, 147 strlen(LOCKED_PASSWD_PREFIX)) == 0) 148 locked = 1; 149 #endif 150 #ifdef LOCKED_PASSWD_SUBSTR 151 if (strstr(passwd, LOCKED_PASSWD_SUBSTR)) 152 locked = 1; 153 #endif 154 #ifdef USE_LIBIAF 155 free((void *) passwd); 156 #endif /* USE_LIBIAF */ 157 if (locked) { 158 logit("User %.100s not allowed because account is locked", 159 pw->pw_name); 160 return 0; 161 } 162 } 163 164 /* 165 * Deny if shell does not exist or is not executable unless we 166 * are chrooting. 167 */ 168 if (options.chroot_directory == NULL || 169 strcasecmp(options.chroot_directory, "none") == 0) { 170 char *shell = xstrdup((pw->pw_shell[0] == '\0') ? 171 _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */ 172 173 if (stat(shell, &st) != 0) { 174 logit("User %.100s not allowed because shell %.100s " 175 "does not exist", pw->pw_name, shell); 176 free(shell); 177 return 0; 178 } 179 if (S_ISREG(st.st_mode) == 0 || 180 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) { 181 logit("User %.100s not allowed because shell %.100s " 182 "is not executable", pw->pw_name, shell); 183 free(shell); 184 return 0; 185 } 186 free(shell); 187 } 188 189 if (options.num_deny_users > 0 || options.num_allow_users > 0 || 190 options.num_deny_groups > 0 || options.num_allow_groups > 0) { 191 hostname = auth_get_canonical_hostname(ssh, options.use_dns); 192 ipaddr = ssh_remote_ipaddr(ssh); 193 } 194 195 /* Return false if user is listed in DenyUsers */ 196 if (options.num_deny_users > 0) { 197 for (i = 0; i < options.num_deny_users; i++) { 198 r = match_user(pw->pw_name, hostname, ipaddr, 199 options.deny_users[i]); 200 if (r < 0) { 201 fatal("Invalid DenyUsers pattern \"%.100s\"", 202 options.deny_users[i]); 203 } else if (r != 0) { 204 logit("User %.100s from %.100s not allowed " 205 "because listed in DenyUsers", 206 pw->pw_name, hostname); 207 return 0; 208 } 209 } 210 } 211 /* Return false if AllowUsers isn't empty and user isn't listed there */ 212 if (options.num_allow_users > 0) { 213 for (i = 0; i < options.num_allow_users; i++) { 214 r = match_user(pw->pw_name, hostname, ipaddr, 215 options.allow_users[i]); 216 if (r < 0) { 217 fatal("Invalid AllowUsers pattern \"%.100s\"", 218 options.allow_users[i]); 219 } else if (r == 1) 220 break; 221 } 222 /* i < options.num_allow_users iff we break for loop */ 223 if (i >= options.num_allow_users) { 224 logit("User %.100s from %.100s not allowed because " 225 "not listed in AllowUsers", pw->pw_name, hostname); 226 return 0; 227 } 228 } 229 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { 230 /* Get the user's group access list (primary and supplementary) */ 231 if (ga_init(pw->pw_name, pw->pw_gid) == 0) { 232 logit("User %.100s from %.100s not allowed because " 233 "not in any group", pw->pw_name, hostname); 234 return 0; 235 } 236 237 /* Return false if one of user's groups is listed in DenyGroups */ 238 if (options.num_deny_groups > 0) 239 if (ga_match(options.deny_groups, 240 options.num_deny_groups)) { 241 ga_free(); 242 logit("User %.100s from %.100s not allowed " 243 "because a group is listed in DenyGroups", 244 pw->pw_name, hostname); 245 return 0; 246 } 247 /* 248 * Return false if AllowGroups isn't empty and one of user's groups 249 * isn't listed there 250 */ 251 if (options.num_allow_groups > 0) 252 if (!ga_match(options.allow_groups, 253 options.num_allow_groups)) { 254 ga_free(); 255 logit("User %.100s from %.100s not allowed " 256 "because none of user's groups are listed " 257 "in AllowGroups", pw->pw_name, hostname); 258 return 0; 259 } 260 ga_free(); 261 } 262 263 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER 264 if (!sys_auth_allowed_user(pw, &loginmsg)) 265 return 0; 266 #endif 267 268 /* We found no reason not to let this user try to log on... */ 269 return 1; 270 } 271 272 void 273 auth_info(Authctxt *authctxt, const char *fmt, ...) 274 { 275 va_list ap; 276 int i; 277 278 free(authctxt->info); 279 authctxt->info = NULL; 280 281 va_start(ap, fmt); 282 i = vasprintf(&authctxt->info, fmt, ap); 283 va_end(ap); 284 285 if (i < 0 || authctxt->info == NULL) 286 fatal("vasprintf failed"); 287 } 288 289 void 290 auth_log(Authctxt *authctxt, int authenticated, int partial, 291 const char *method, const char *submethod) 292 { 293 struct ssh *ssh = active_state; /* XXX */ 294 void (*authlog) (const char *fmt,...) = verbose; 295 char *authmsg; 296 297 if (use_privsep && !mm_is_monitor() && !authctxt->postponed) 298 return; 299 300 /* Raise logging level */ 301 if (authenticated == 1 || 302 !authctxt->valid || 303 authctxt->failures >= options.max_authtries / 2 || 304 strcmp(method, "password") == 0) 305 authlog = logit; 306 307 if (authctxt->postponed) 308 authmsg = "Postponed"; 309 else if (partial) 310 authmsg = "Partial"; 311 else { 312 authmsg = authenticated ? "Accepted" : "Failed"; 313 if (authenticated) 314 BLACKLIST_NOTIFY(BLACKLIST_AUTH_OK); 315 } 316 317 authlog("%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s", 318 authmsg, 319 method, 320 submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod, 321 authctxt->valid ? "" : "invalid user ", 322 authctxt->user, 323 ssh_remote_ipaddr(ssh), 324 ssh_remote_port(ssh), 325 authctxt->info != NULL ? ": " : "", 326 authctxt->info != NULL ? authctxt->info : ""); 327 free(authctxt->info); 328 authctxt->info = NULL; 329 330 #ifdef CUSTOM_FAILED_LOGIN 331 if (authenticated == 0 && !authctxt->postponed && 332 (strcmp(method, "password") == 0 || 333 strncmp(method, "keyboard-interactive", 20) == 0 || 334 strcmp(method, "challenge-response") == 0)) 335 record_failed_login(authctxt->user, 336 auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); 337 # ifdef WITH_AIXAUTHENTICATE 338 if (authenticated) 339 sys_auth_record_login(authctxt->user, 340 auth_get_canonical_hostname(ssh, options.use_dns), "ssh", 341 &loginmsg); 342 # endif 343 #endif 344 #ifdef SSH_AUDIT_EVENTS 345 if (authenticated == 0 && !authctxt->postponed) 346 audit_event(audit_classify_auth(method)); 347 #endif 348 } 349 350 351 void 352 auth_maxtries_exceeded(Authctxt *authctxt) 353 { 354 struct ssh *ssh = active_state; /* XXX */ 355 356 error("maximum authentication attempts exceeded for " 357 "%s%.100s from %.200s port %d ssh2", 358 authctxt->valid ? "" : "invalid user ", 359 authctxt->user, 360 ssh_remote_ipaddr(ssh), 361 ssh_remote_port(ssh)); 362 packet_disconnect("Too many authentication failures"); 363 /* NOTREACHED */ 364 } 365 366 /* 367 * Check whether root logins are disallowed. 368 */ 369 int 370 auth_root_allowed(const char *method) 371 { 372 struct ssh *ssh = active_state; /* XXX */ 373 374 switch (options.permit_root_login) { 375 case PERMIT_YES: 376 return 1; 377 case PERMIT_NO_PASSWD: 378 if (strcmp(method, "publickey") == 0 || 379 strcmp(method, "hostbased") == 0 || 380 strcmp(method, "gssapi-with-mic") == 0) 381 return 1; 382 break; 383 case PERMIT_FORCED_ONLY: 384 if (forced_command) { 385 logit("Root login accepted for forced command."); 386 return 1; 387 } 388 break; 389 } 390 logit("ROOT LOGIN REFUSED FROM %.200s port %d", 391 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 392 return 0; 393 } 394 395 396 /* 397 * Given a template and a passwd structure, build a filename 398 * by substituting % tokenised options. Currently, %% becomes '%', 399 * %h becomes the home directory and %u the username. 400 * 401 * This returns a buffer allocated by xmalloc. 402 */ 403 char * 404 expand_authorized_keys(const char *filename, struct passwd *pw) 405 { 406 char *file, ret[PATH_MAX]; 407 int i; 408 409 file = percent_expand(filename, "h", pw->pw_dir, 410 "u", pw->pw_name, (char *)NULL); 411 412 /* 413 * Ensure that filename starts anchored. If not, be backward 414 * compatible and prepend the '%h/' 415 */ 416 if (*file == '/') 417 return (file); 418 419 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file); 420 if (i < 0 || (size_t)i >= sizeof(ret)) 421 fatal("expand_authorized_keys: path too long"); 422 free(file); 423 return (xstrdup(ret)); 424 } 425 426 char * 427 authorized_principals_file(struct passwd *pw) 428 { 429 if (options.authorized_principals_file == NULL) 430 return NULL; 431 return expand_authorized_keys(options.authorized_principals_file, pw); 432 } 433 434 /* return ok if key exists in sysfile or userfile */ 435 HostStatus 436 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host, 437 const char *sysfile, const char *userfile) 438 { 439 char *user_hostfile; 440 struct stat st; 441 HostStatus host_status; 442 struct hostkeys *hostkeys; 443 const struct hostkey_entry *found; 444 445 hostkeys = init_hostkeys(); 446 load_hostkeys(hostkeys, host, sysfile); 447 if (userfile != NULL) { 448 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid); 449 if (options.strict_modes && 450 (stat(user_hostfile, &st) == 0) && 451 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || 452 (st.st_mode & 022) != 0)) { 453 logit("Authentication refused for %.100s: " 454 "bad owner or modes for %.200s", 455 pw->pw_name, user_hostfile); 456 auth_debug_add("Ignored %.200s: bad ownership or modes", 457 user_hostfile); 458 } else { 459 temporarily_use_uid(pw); 460 load_hostkeys(hostkeys, host, user_hostfile); 461 restore_uid(); 462 } 463 free(user_hostfile); 464 } 465 host_status = check_key_in_hostkeys(hostkeys, key, &found); 466 if (host_status == HOST_REVOKED) 467 error("WARNING: revoked key for %s attempted authentication", 468 found->host); 469 else if (host_status == HOST_OK) 470 debug("%s: key for %s found at %s:%ld", __func__, 471 found->host, found->file, found->line); 472 else 473 debug("%s: key for host %s not found", __func__, host); 474 475 free_hostkeys(hostkeys); 476 477 return host_status; 478 } 479 480 /* 481 * Check a given path for security. This is defined as all components 482 * of the path to the file must be owned by either the owner of 483 * of the file or root and no directories must be group or world writable. 484 * 485 * XXX Should any specific check be done for sym links ? 486 * 487 * Takes a file name, its stat information (preferably from fstat() to 488 * avoid races), the uid of the expected owner, their home directory and an 489 * error buffer plus max size as arguments. 490 * 491 * Returns 0 on success and -1 on failure 492 */ 493 int 494 auth_secure_path(const char *name, struct stat *stp, const char *pw_dir, 495 uid_t uid, char *err, size_t errlen) 496 { 497 char buf[PATH_MAX], homedir[PATH_MAX]; 498 char *cp; 499 int comparehome = 0; 500 struct stat st; 501 502 if (realpath(name, buf) == NULL) { 503 snprintf(err, errlen, "realpath %s failed: %s", name, 504 strerror(errno)); 505 return -1; 506 } 507 if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL) 508 comparehome = 1; 509 510 if (!S_ISREG(stp->st_mode)) { 511 snprintf(err, errlen, "%s is not a regular file", buf); 512 return -1; 513 } 514 if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) || 515 (stp->st_mode & 022) != 0) { 516 snprintf(err, errlen, "bad ownership or modes for file %s", 517 buf); 518 return -1; 519 } 520 521 /* for each component of the canonical path, walking upwards */ 522 for (;;) { 523 if ((cp = dirname(buf)) == NULL) { 524 snprintf(err, errlen, "dirname() failed"); 525 return -1; 526 } 527 strlcpy(buf, cp, sizeof(buf)); 528 529 if (stat(buf, &st) < 0 || 530 (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) || 531 (st.st_mode & 022) != 0) { 532 snprintf(err, errlen, 533 "bad ownership or modes for directory %s", buf); 534 return -1; 535 } 536 537 /* If are past the homedir then we can stop */ 538 if (comparehome && strcmp(homedir, buf) == 0) 539 break; 540 541 /* 542 * dirname should always complete with a "/" path, 543 * but we can be paranoid and check for "." too 544 */ 545 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0)) 546 break; 547 } 548 return 0; 549 } 550 551 /* 552 * Version of secure_path() that accepts an open file descriptor to 553 * avoid races. 554 * 555 * Returns 0 on success and -1 on failure 556 */ 557 static int 558 secure_filename(FILE *f, const char *file, struct passwd *pw, 559 char *err, size_t errlen) 560 { 561 struct stat st; 562 563 /* check the open file to avoid races */ 564 if (fstat(fileno(f), &st) < 0) { 565 snprintf(err, errlen, "cannot stat file %s: %s", 566 file, strerror(errno)); 567 return -1; 568 } 569 return auth_secure_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen); 570 } 571 572 static FILE * 573 auth_openfile(const char *file, struct passwd *pw, int strict_modes, 574 int log_missing, char *file_type) 575 { 576 char line[1024]; 577 struct stat st; 578 int fd; 579 FILE *f; 580 581 if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) { 582 if (log_missing || errno != ENOENT) 583 debug("Could not open %s '%s': %s", file_type, file, 584 strerror(errno)); 585 return NULL; 586 } 587 588 if (fstat(fd, &st) < 0) { 589 close(fd); 590 return NULL; 591 } 592 if (!S_ISREG(st.st_mode)) { 593 logit("User %s %s %s is not a regular file", 594 pw->pw_name, file_type, file); 595 close(fd); 596 return NULL; 597 } 598 unset_nonblock(fd); 599 if ((f = fdopen(fd, "r")) == NULL) { 600 close(fd); 601 return NULL; 602 } 603 if (strict_modes && 604 secure_filename(f, file, pw, line, sizeof(line)) != 0) { 605 fclose(f); 606 logit("Authentication refused: %s", line); 607 auth_debug_add("Ignored %s: %s", file_type, line); 608 return NULL; 609 } 610 611 return f; 612 } 613 614 615 FILE * 616 auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes) 617 { 618 return auth_openfile(file, pw, strict_modes, 1, "authorized keys"); 619 } 620 621 FILE * 622 auth_openprincipals(const char *file, struct passwd *pw, int strict_modes) 623 { 624 return auth_openfile(file, pw, strict_modes, 0, 625 "authorized principals"); 626 } 627 628 struct passwd * 629 getpwnamallow(const char *user) 630 { 631 struct ssh *ssh = active_state; /* XXX */ 632 #ifdef HAVE_LOGIN_CAP 633 extern login_cap_t *lc; 634 #ifdef BSD_AUTH 635 auth_session_t *as; 636 #endif 637 #endif 638 struct passwd *pw; 639 struct connection_info *ci = get_connection_info(1, options.use_dns); 640 641 ci->user = user; 642 parse_server_match_config(&options, ci); 643 644 #if defined(_AIX) && defined(HAVE_SETAUTHDB) 645 aix_setauthdb(user); 646 #endif 647 648 pw = getpwnam(user); 649 650 #if defined(_AIX) && defined(HAVE_SETAUTHDB) 651 aix_restoreauthdb(); 652 #endif 653 #ifdef HAVE_CYGWIN 654 /* 655 * Windows usernames are case-insensitive. To avoid later problems 656 * when trying to match the username, the user is only allowed to 657 * login if the username is given in the same case as stored in the 658 * user database. 659 */ 660 if (pw != NULL && strcmp(user, pw->pw_name) != 0) { 661 logit("Login name %.100s does not match stored username %.100s", 662 user, pw->pw_name); 663 pw = NULL; 664 } 665 #endif 666 if (pw == NULL) { 667 BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL); 668 logit("Invalid user %.100s from %.100s port %d", 669 user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 670 #ifdef CUSTOM_FAILED_LOGIN 671 record_failed_login(user, 672 auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); 673 #endif 674 #ifdef SSH_AUDIT_EVENTS 675 audit_event(SSH_INVALID_USER); 676 #endif /* SSH_AUDIT_EVENTS */ 677 return (NULL); 678 } 679 if (!allowed_user(pw)) 680 return (NULL); 681 #ifdef HAVE_LOGIN_CAP 682 if ((lc = login_getpwclass(pw)) == NULL) { 683 debug("unable to get login class: %s", user); 684 return (NULL); 685 } 686 #ifdef BSD_AUTH 687 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 || 688 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) { 689 debug("Approval failure for %s", user); 690 pw = NULL; 691 } 692 if (as != NULL) 693 auth_close(as); 694 #endif 695 #endif 696 if (pw != NULL) 697 return (pwcopy(pw)); 698 return (NULL); 699 } 700 701 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */ 702 int 703 auth_key_is_revoked(Key *key) 704 { 705 char *fp = NULL; 706 int r; 707 708 if (options.revoked_keys_file == NULL) 709 return 0; 710 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 711 SSH_FP_DEFAULT)) == NULL) { 712 r = SSH_ERR_ALLOC_FAIL; 713 error("%s: fingerprint key: %s", __func__, ssh_err(r)); 714 goto out; 715 } 716 717 r = sshkey_check_revoked(key, options.revoked_keys_file); 718 switch (r) { 719 case 0: 720 break; /* not revoked */ 721 case SSH_ERR_KEY_REVOKED: 722 error("Authentication key %s %s revoked by file %s", 723 sshkey_type(key), fp, options.revoked_keys_file); 724 goto out; 725 default: 726 error("Error checking authentication key %s %s in " 727 "revoked keys file %s: %s", sshkey_type(key), fp, 728 options.revoked_keys_file, ssh_err(r)); 729 goto out; 730 } 731 732 /* Success */ 733 r = 0; 734 735 out: 736 free(fp); 737 return r == 0 ? 0 : 1; 738 } 739 740 void 741 auth_debug_add(const char *fmt,...) 742 { 743 char buf[1024]; 744 va_list args; 745 746 if (!auth_debug_init) 747 return; 748 749 va_start(args, fmt); 750 vsnprintf(buf, sizeof(buf), fmt, args); 751 va_end(args); 752 buffer_put_cstring(&auth_debug, buf); 753 } 754 755 void 756 auth_debug_send(void) 757 { 758 char *msg; 759 760 if (!auth_debug_init) 761 return; 762 while (buffer_len(&auth_debug)) { 763 msg = buffer_get_string(&auth_debug, NULL); 764 packet_send_debug("%s", msg); 765 free(msg); 766 } 767 } 768 769 void 770 auth_debug_reset(void) 771 { 772 if (auth_debug_init) 773 buffer_clear(&auth_debug); 774 else { 775 buffer_init(&auth_debug); 776 auth_debug_init = 1; 777 } 778 } 779 780 struct passwd * 781 fakepw(void) 782 { 783 static struct passwd fake; 784 785 memset(&fake, 0, sizeof(fake)); 786 fake.pw_name = "NOUSER"; 787 fake.pw_passwd = 788 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK"; 789 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS 790 fake.pw_gecos = "NOUSER"; 791 #endif 792 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid; 793 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid; 794 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS 795 fake.pw_class = ""; 796 #endif 797 fake.pw_dir = "/nonexist"; 798 fake.pw_shell = "/nonexist"; 799 800 return (&fake); 801 } 802 803 /* 804 * Returns the remote DNS hostname as a string. The returned string must not 805 * be freed. NB. this will usually trigger a DNS query the first time it is 806 * called. 807 * This function does additional checks on the hostname to mitigate some 808 * attacks on legacy rhosts-style authentication. 809 * XXX is RhostsRSAAuthentication vulnerable to these? 810 * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?) 811 */ 812 813 static char * 814 remote_hostname(struct ssh *ssh) 815 { 816 struct sockaddr_storage from; 817 socklen_t fromlen; 818 struct addrinfo hints, *ai, *aitop; 819 char name[NI_MAXHOST], ntop2[NI_MAXHOST]; 820 const char *ntop = ssh_remote_ipaddr(ssh); 821 822 /* Get IP address of client. */ 823 fromlen = sizeof(from); 824 memset(&from, 0, sizeof(from)); 825 if (getpeername(ssh_packet_get_connection_in(ssh), 826 (struct sockaddr *)&from, &fromlen) < 0) { 827 debug("getpeername failed: %.100s", strerror(errno)); 828 return strdup(ntop); 829 } 830 831 ipv64_normalise_mapped(&from, &fromlen); 832 if (from.ss_family == AF_INET6) 833 fromlen = sizeof(struct sockaddr_in6); 834 835 debug3("Trying to reverse map address %.100s.", ntop); 836 /* Map the IP address to a host name. */ 837 if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), 838 NULL, 0, NI_NAMEREQD) != 0) { 839 /* Host name not found. Use ip address. */ 840 return strdup(ntop); 841 } 842 843 /* 844 * if reverse lookup result looks like a numeric hostname, 845 * someone is trying to trick us by PTR record like following: 846 * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 847 */ 848 memset(&hints, 0, sizeof(hints)); 849 hints.ai_socktype = SOCK_DGRAM; /*dummy*/ 850 hints.ai_flags = AI_NUMERICHOST; 851 if (getaddrinfo(name, NULL, &hints, &ai) == 0) { 852 logit("Nasty PTR record \"%s\" is set up for %s, ignoring", 853 name, ntop); 854 freeaddrinfo(ai); 855 return strdup(ntop); 856 } 857 858 /* Names are stored in lowercase. */ 859 lowercase(name); 860 861 /* 862 * Map it back to an IP address and check that the given 863 * address actually is an address of this host. This is 864 * necessary because anyone with access to a name server can 865 * define arbitrary names for an IP address. Mapping from 866 * name to IP address can be trusted better (but can still be 867 * fooled if the intruder has access to the name server of 868 * the domain). 869 */ 870 memset(&hints, 0, sizeof(hints)); 871 hints.ai_family = from.ss_family; 872 hints.ai_socktype = SOCK_STREAM; 873 if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { 874 logit("reverse mapping checking getaddrinfo for %.700s " 875 "[%s] failed.", name, ntop); 876 return strdup(ntop); 877 } 878 /* Look for the address from the list of addresses. */ 879 for (ai = aitop; ai; ai = ai->ai_next) { 880 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, 881 sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && 882 (strcmp(ntop, ntop2) == 0)) 883 break; 884 } 885 freeaddrinfo(aitop); 886 /* If we reached the end of the list, the address was not there. */ 887 if (ai == NULL) { 888 /* Address not found for the host name. */ 889 logit("Address %.100s maps to %.600s, but this does not " 890 "map back to the address.", ntop, name); 891 return strdup(ntop); 892 } 893 return strdup(name); 894 } 895 896 /* 897 * Return the canonical name of the host in the other side of the current 898 * connection. The host name is cached, so it is efficient to call this 899 * several times. 900 */ 901 902 const char * 903 auth_get_canonical_hostname(struct ssh *ssh, int use_dns) 904 { 905 static char *dnsname; 906 907 if (!use_dns) 908 return ssh_remote_ipaddr(ssh); 909 else if (dnsname != NULL) 910 return dnsname; 911 else { 912 dnsname = remote_hostname(ssh); 913 return dnsname; 914 } 915 } 916