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 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 int r; 107 #ifdef USE_SHADOW 108 struct spwd *spw = NULL; 109 #endif 110 111 /* Shouldn't be called if pw is NULL, but better safe than sorry... */ 112 if (!pw || !pw->pw_name) 113 return 0; 114 115 #ifdef USE_SHADOW 116 if (!options.use_pam) 117 spw = getspnam(pw->pw_name); 118 #ifdef HAS_SHADOW_EXPIRE 119 if (!options.use_pam && spw != NULL && auth_shadow_acctexpired(spw)) 120 return 0; 121 #endif /* HAS_SHADOW_EXPIRE */ 122 #endif /* USE_SHADOW */ 123 124 /* grab passwd field for locked account check */ 125 passwd = pw->pw_passwd; 126 #ifdef USE_SHADOW 127 if (spw != NULL) 128 #ifdef USE_LIBIAF 129 passwd = get_iaf_password(pw); 130 #else 131 passwd = spw->sp_pwdp; 132 #endif /* USE_LIBIAF */ 133 #endif 134 135 /* check for locked account */ 136 if (!options.use_pam && passwd && *passwd) { 137 int locked = 0; 138 139 #ifdef LOCKED_PASSWD_STRING 140 if (strcmp(passwd, LOCKED_PASSWD_STRING) == 0) 141 locked = 1; 142 #endif 143 #ifdef LOCKED_PASSWD_PREFIX 144 if (strncmp(passwd, LOCKED_PASSWD_PREFIX, 145 strlen(LOCKED_PASSWD_PREFIX)) == 0) 146 locked = 1; 147 #endif 148 #ifdef LOCKED_PASSWD_SUBSTR 149 if (strstr(passwd, LOCKED_PASSWD_SUBSTR)) 150 locked = 1; 151 #endif 152 #ifdef USE_LIBIAF 153 free((void *) passwd); 154 #endif /* USE_LIBIAF */ 155 if (locked) { 156 logit("User %.100s not allowed because account is locked", 157 pw->pw_name); 158 return 0; 159 } 160 } 161 162 /* 163 * Deny if shell does not exist or is not executable unless we 164 * are chrooting. 165 */ 166 if (options.chroot_directory == NULL || 167 strcasecmp(options.chroot_directory, "none") == 0) { 168 char *shell = xstrdup((pw->pw_shell[0] == '\0') ? 169 _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */ 170 171 if (stat(shell, &st) != 0) { 172 logit("User %.100s not allowed because shell %.100s " 173 "does not exist", pw->pw_name, shell); 174 free(shell); 175 return 0; 176 } 177 if (S_ISREG(st.st_mode) == 0 || 178 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) { 179 logit("User %.100s not allowed because shell %.100s " 180 "is not executable", pw->pw_name, shell); 181 free(shell); 182 return 0; 183 } 184 free(shell); 185 } 186 187 if (options.num_deny_users > 0 || options.num_allow_users > 0 || 188 options.num_deny_groups > 0 || options.num_allow_groups > 0) { 189 hostname = auth_get_canonical_hostname(ssh, options.use_dns); 190 ipaddr = ssh_remote_ipaddr(ssh); 191 } 192 193 /* Return false if user is listed in DenyUsers */ 194 if (options.num_deny_users > 0) { 195 for (i = 0; i < options.num_deny_users; i++) { 196 r = match_user(pw->pw_name, hostname, ipaddr, 197 options.deny_users[i]); 198 if (r < 0) { 199 fatal("Invalid DenyUsers pattern \"%.100s\"", 200 options.deny_users[i]); 201 } else if (r != 0) { 202 logit("User %.100s from %.100s not allowed " 203 "because listed in DenyUsers", 204 pw->pw_name, hostname); 205 return 0; 206 } 207 } 208 } 209 /* Return false if AllowUsers isn't empty and user isn't listed there */ 210 if (options.num_allow_users > 0) { 211 for (i = 0; i < options.num_allow_users; i++) { 212 r = match_user(pw->pw_name, hostname, ipaddr, 213 options.allow_users[i]); 214 if (r < 0) { 215 fatal("Invalid AllowUsers pattern \"%.100s\"", 216 options.allow_users[i]); 217 } else if (r == 1) 218 break; 219 } 220 /* i < options.num_allow_users iff we break for loop */ 221 if (i >= options.num_allow_users) { 222 logit("User %.100s from %.100s not allowed because " 223 "not listed in AllowUsers", pw->pw_name, hostname); 224 return 0; 225 } 226 } 227 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { 228 /* Get the user's group access list (primary and supplementary) */ 229 if (ga_init(pw->pw_name, pw->pw_gid) == 0) { 230 logit("User %.100s from %.100s not allowed because " 231 "not in any group", pw->pw_name, hostname); 232 return 0; 233 } 234 235 /* Return false if one of user's groups is listed in DenyGroups */ 236 if (options.num_deny_groups > 0) 237 if (ga_match(options.deny_groups, 238 options.num_deny_groups)) { 239 ga_free(); 240 logit("User %.100s from %.100s not allowed " 241 "because a group is listed in DenyGroups", 242 pw->pw_name, hostname); 243 return 0; 244 } 245 /* 246 * Return false if AllowGroups isn't empty and one of user's groups 247 * isn't listed there 248 */ 249 if (options.num_allow_groups > 0) 250 if (!ga_match(options.allow_groups, 251 options.num_allow_groups)) { 252 ga_free(); 253 logit("User %.100s from %.100s not allowed " 254 "because none of user's groups are listed " 255 "in AllowGroups", pw->pw_name, hostname); 256 return 0; 257 } 258 ga_free(); 259 } 260 261 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER 262 if (!sys_auth_allowed_user(pw, &loginmsg)) 263 return 0; 264 #endif 265 266 /* We found no reason not to let this user try to log on... */ 267 return 1; 268 } 269 270 void 271 auth_info(Authctxt *authctxt, const char *fmt, ...) 272 { 273 va_list ap; 274 int i; 275 276 free(authctxt->info); 277 authctxt->info = NULL; 278 279 va_start(ap, fmt); 280 i = vasprintf(&authctxt->info, fmt, ap); 281 va_end(ap); 282 283 if (i < 0 || authctxt->info == NULL) 284 fatal("vasprintf failed"); 285 } 286 287 void 288 auth_log(Authctxt *authctxt, int authenticated, int partial, 289 const char *method, const char *submethod) 290 { 291 struct ssh *ssh = active_state; /* XXX */ 292 void (*authlog) (const char *fmt,...) = verbose; 293 char *authmsg; 294 295 if (use_privsep && !mm_is_monitor() && !authctxt->postponed) 296 return; 297 298 /* Raise logging level */ 299 if (authenticated == 1 || 300 !authctxt->valid || 301 authctxt->failures >= options.max_authtries / 2 || 302 strcmp(method, "password") == 0) 303 authlog = logit; 304 305 if (authctxt->postponed) 306 authmsg = "Postponed"; 307 else if (partial) 308 authmsg = "Partial"; 309 else 310 authmsg = authenticated ? "Accepted" : "Failed"; 311 312 authlog("%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s", 313 authmsg, 314 method, 315 submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod, 316 authctxt->valid ? "" : "invalid user ", 317 authctxt->user, 318 ssh_remote_ipaddr(ssh), 319 ssh_remote_port(ssh), 320 authctxt->info != NULL ? ": " : "", 321 authctxt->info != NULL ? authctxt->info : ""); 322 free(authctxt->info); 323 authctxt->info = NULL; 324 325 #ifdef CUSTOM_FAILED_LOGIN 326 if (authenticated == 0 && !authctxt->postponed && 327 (strcmp(method, "password") == 0 || 328 strncmp(method, "keyboard-interactive", 20) == 0 || 329 strcmp(method, "challenge-response") == 0)) 330 record_failed_login(authctxt->user, 331 auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); 332 # ifdef WITH_AIXAUTHENTICATE 333 if (authenticated) 334 sys_auth_record_login(authctxt->user, 335 auth_get_canonical_hostname(ssh, options.use_dns), "ssh", 336 &loginmsg); 337 # endif 338 #endif 339 #ifdef SSH_AUDIT_EVENTS 340 if (authenticated == 0 && !authctxt->postponed) 341 audit_event(audit_classify_auth(method)); 342 #endif 343 } 344 345 346 void 347 auth_maxtries_exceeded(Authctxt *authctxt) 348 { 349 struct ssh *ssh = active_state; /* XXX */ 350 351 error("maximum authentication attempts exceeded for " 352 "%s%.100s from %.200s port %d ssh2", 353 authctxt->valid ? "" : "invalid user ", 354 authctxt->user, 355 ssh_remote_ipaddr(ssh), 356 ssh_remote_port(ssh)); 357 packet_disconnect("Too many authentication failures"); 358 /* NOTREACHED */ 359 } 360 361 /* 362 * Check whether root logins are disallowed. 363 */ 364 int 365 auth_root_allowed(const char *method) 366 { 367 struct ssh *ssh = active_state; /* XXX */ 368 369 switch (options.permit_root_login) { 370 case PERMIT_YES: 371 return 1; 372 case PERMIT_NO_PASSWD: 373 if (strcmp(method, "publickey") == 0 || 374 strcmp(method, "hostbased") == 0 || 375 strcmp(method, "gssapi-with-mic") == 0) 376 return 1; 377 break; 378 case PERMIT_FORCED_ONLY: 379 if (forced_command) { 380 logit("Root login accepted for forced command."); 381 return 1; 382 } 383 break; 384 } 385 logit("ROOT LOGIN REFUSED FROM %.200s port %d", 386 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 387 return 0; 388 } 389 390 391 /* 392 * Given a template and a passwd structure, build a filename 393 * by substituting % tokenised options. Currently, %% becomes '%', 394 * %h becomes the home directory and %u the username. 395 * 396 * This returns a buffer allocated by xmalloc. 397 */ 398 char * 399 expand_authorized_keys(const char *filename, struct passwd *pw) 400 { 401 char *file, ret[PATH_MAX]; 402 int i; 403 404 file = percent_expand(filename, "h", pw->pw_dir, 405 "u", pw->pw_name, (char *)NULL); 406 407 /* 408 * Ensure that filename starts anchored. If not, be backward 409 * compatible and prepend the '%h/' 410 */ 411 if (*file == '/') 412 return (file); 413 414 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file); 415 if (i < 0 || (size_t)i >= sizeof(ret)) 416 fatal("expand_authorized_keys: path too long"); 417 free(file); 418 return (xstrdup(ret)); 419 } 420 421 char * 422 authorized_principals_file(struct passwd *pw) 423 { 424 if (options.authorized_principals_file == NULL) 425 return NULL; 426 return expand_authorized_keys(options.authorized_principals_file, pw); 427 } 428 429 /* return ok if key exists in sysfile or userfile */ 430 HostStatus 431 check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host, 432 const char *sysfile, const char *userfile) 433 { 434 char *user_hostfile; 435 struct stat st; 436 HostStatus host_status; 437 struct hostkeys *hostkeys; 438 const struct hostkey_entry *found; 439 440 hostkeys = init_hostkeys(); 441 load_hostkeys(hostkeys, host, sysfile); 442 if (userfile != NULL) { 443 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid); 444 if (options.strict_modes && 445 (stat(user_hostfile, &st) == 0) && 446 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || 447 (st.st_mode & 022) != 0)) { 448 logit("Authentication refused for %.100s: " 449 "bad owner or modes for %.200s", 450 pw->pw_name, user_hostfile); 451 auth_debug_add("Ignored %.200s: bad ownership or modes", 452 user_hostfile); 453 } else { 454 temporarily_use_uid(pw); 455 load_hostkeys(hostkeys, host, user_hostfile); 456 restore_uid(); 457 } 458 free(user_hostfile); 459 } 460 host_status = check_key_in_hostkeys(hostkeys, key, &found); 461 if (host_status == HOST_REVOKED) 462 error("WARNING: revoked key for %s attempted authentication", 463 found->host); 464 else if (host_status == HOST_OK) 465 debug("%s: key for %s found at %s:%ld", __func__, 466 found->host, found->file, found->line); 467 else 468 debug("%s: key for host %s not found", __func__, host); 469 470 free_hostkeys(hostkeys); 471 472 return host_status; 473 } 474 475 /* 476 * Check a given path for security. This is defined as all components 477 * of the path to the file must be owned by either the owner of 478 * of the file or root and no directories must be group or world writable. 479 * 480 * XXX Should any specific check be done for sym links ? 481 * 482 * Takes a file name, its stat information (preferably from fstat() to 483 * avoid races), the uid of the expected owner, their home directory and an 484 * error buffer plus max size as arguments. 485 * 486 * Returns 0 on success and -1 on failure 487 */ 488 int 489 auth_secure_path(const char *name, struct stat *stp, const char *pw_dir, 490 uid_t uid, char *err, size_t errlen) 491 { 492 char buf[PATH_MAX], homedir[PATH_MAX]; 493 char *cp; 494 int comparehome = 0; 495 struct stat st; 496 497 if (realpath(name, buf) == NULL) { 498 snprintf(err, errlen, "realpath %s failed: %s", name, 499 strerror(errno)); 500 return -1; 501 } 502 if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL) 503 comparehome = 1; 504 505 if (!S_ISREG(stp->st_mode)) { 506 snprintf(err, errlen, "%s is not a regular file", buf); 507 return -1; 508 } 509 if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) || 510 (stp->st_mode & 022) != 0) { 511 #if defined(ANDROID) 512 /* needed to allow root login on Android. */ 513 if (getuid() != 0) 514 #endif 515 { 516 snprintf(err, errlen, "bad ownership or modes for file %s", 517 buf); 518 return -1; 519 } 520 } 521 522 /* for each component of the canonical path, walking upwards */ 523 for (;;) { 524 if ((cp = dirname(buf)) == NULL) { 525 snprintf(err, errlen, "dirname() failed"); 526 return -1; 527 } 528 strlcpy(buf, cp, sizeof(buf)); 529 530 #if !defined(ANDROID) 531 /* /data is owned by system user, which causes this check to fail */ 532 if (stat(buf, &st) < 0 || 533 (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) || 534 (st.st_mode & 022) != 0) { 535 snprintf(err, errlen, 536 "bad ownership or modes for directory %s", buf); 537 return -1; 538 } 539 #endif 540 541 /* If are past the homedir then we can stop */ 542 if (comparehome && strcmp(homedir, buf) == 0) 543 break; 544 545 /* 546 * dirname should always complete with a "/" path, 547 * but we can be paranoid and check for "." too 548 */ 549 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0)) 550 break; 551 } 552 return 0; 553 } 554 555 /* 556 * Version of secure_path() that accepts an open file descriptor to 557 * avoid races. 558 * 559 * Returns 0 on success and -1 on failure 560 */ 561 static int 562 secure_filename(FILE *f, const char *file, struct passwd *pw, 563 char *err, size_t errlen) 564 { 565 struct stat st; 566 567 /* check the open file to avoid races */ 568 if (fstat(fileno(f), &st) < 0) { 569 snprintf(err, errlen, "cannot stat file %s: %s", 570 file, strerror(errno)); 571 return -1; 572 } 573 return auth_secure_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen); 574 } 575 576 static FILE * 577 auth_openfile(const char *file, struct passwd *pw, int strict_modes, 578 int log_missing, char *file_type) 579 { 580 char line[1024]; 581 struct stat st; 582 int fd; 583 FILE *f; 584 585 if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) { 586 if (log_missing || errno != ENOENT) 587 debug("Could not open %s '%s': %s", file_type, file, 588 strerror(errno)); 589 return NULL; 590 } 591 592 if (fstat(fd, &st) < 0) { 593 close(fd); 594 return NULL; 595 } 596 if (!S_ISREG(st.st_mode)) { 597 logit("User %s %s %s is not a regular file", 598 pw->pw_name, file_type, file); 599 close(fd); 600 return NULL; 601 } 602 unset_nonblock(fd); 603 if ((f = fdopen(fd, "r")) == NULL) { 604 close(fd); 605 return NULL; 606 } 607 if (strict_modes && 608 secure_filename(f, file, pw, line, sizeof(line)) != 0) { 609 fclose(f); 610 logit("Authentication refused: %s", line); 611 auth_debug_add("Ignored %s: %s", file_type, line); 612 return NULL; 613 } 614 615 return f; 616 } 617 618 619 FILE * 620 auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes) 621 { 622 return auth_openfile(file, pw, strict_modes, 1, "authorized keys"); 623 } 624 625 FILE * 626 auth_openprincipals(const char *file, struct passwd *pw, int strict_modes) 627 { 628 return auth_openfile(file, pw, strict_modes, 0, 629 "authorized principals"); 630 } 631 632 struct passwd * 633 getpwnamallow(const char *user) 634 { 635 struct ssh *ssh = active_state; /* XXX */ 636 #ifdef HAVE_LOGIN_CAP 637 extern login_cap_t *lc; 638 #ifdef BSD_AUTH 639 auth_session_t *as; 640 #endif 641 #endif 642 struct passwd *pw; 643 struct connection_info *ci = get_connection_info(1, options.use_dns); 644 645 ci->user = user; 646 parse_server_match_config(&options, ci); 647 648 #if defined(_AIX) && defined(HAVE_SETAUTHDB) 649 aix_setauthdb(user); 650 #endif 651 652 #if defined(ANDROID) 653 // Android has a fixed set of users. Any incoming user that we can't 654 // identify should be authenticated as the shell user. 655 if (strcmp(user, "root") && strcmp(user, "shell")) { 656 logit("Login name %.100s forced to shell", user); 657 user = "shell"; 658 } 659 #endif 660 pw = getpwnam(user); 661 662 #if defined(_AIX) && defined(HAVE_SETAUTHDB) 663 aix_restoreauthdb(); 664 #endif 665 #ifdef HAVE_CYGWIN 666 /* 667 * Windows usernames are case-insensitive. To avoid later problems 668 * when trying to match the username, the user is only allowed to 669 * login if the username is given in the same case as stored in the 670 * user database. 671 */ 672 if (pw != NULL && strcmp(user, pw->pw_name) != 0) { 673 logit("Login name %.100s does not match stored username %.100s", 674 user, pw->pw_name); 675 pw = NULL; 676 } 677 #endif 678 if (pw == NULL) { 679 logit("Invalid user %.100s from %.100s port %d", 680 user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 681 #ifdef CUSTOM_FAILED_LOGIN 682 record_failed_login(user, 683 auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); 684 #endif 685 #ifdef SSH_AUDIT_EVENTS 686 audit_event(SSH_INVALID_USER); 687 #endif /* SSH_AUDIT_EVENTS */ 688 return (NULL); 689 } 690 if (!allowed_user(pw)) 691 return (NULL); 692 #ifdef HAVE_LOGIN_CAP 693 if ((lc = login_getclass(pw->pw_class)) == NULL) { 694 debug("unable to get login class: %s", user); 695 return (NULL); 696 } 697 #ifdef BSD_AUTH 698 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 || 699 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) { 700 debug("Approval failure for %s", user); 701 pw = NULL; 702 } 703 if (as != NULL) 704 auth_close(as); 705 #endif 706 #endif 707 if (pw != NULL) 708 return (pwcopy(pw)); 709 return (NULL); 710 } 711 712 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */ 713 int 714 auth_key_is_revoked(Key *key) 715 { 716 char *fp = NULL; 717 int r; 718 719 if (options.revoked_keys_file == NULL) 720 return 0; 721 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 722 SSH_FP_DEFAULT)) == NULL) { 723 r = SSH_ERR_ALLOC_FAIL; 724 error("%s: fingerprint key: %s", __func__, ssh_err(r)); 725 goto out; 726 } 727 728 r = sshkey_check_revoked(key, options.revoked_keys_file); 729 switch (r) { 730 case 0: 731 break; /* not revoked */ 732 case SSH_ERR_KEY_REVOKED: 733 error("Authentication key %s %s revoked by file %s", 734 sshkey_type(key), fp, options.revoked_keys_file); 735 goto out; 736 default: 737 error("Error checking authentication key %s %s in " 738 "revoked keys file %s: %s", sshkey_type(key), fp, 739 options.revoked_keys_file, ssh_err(r)); 740 goto out; 741 } 742 743 /* Success */ 744 r = 0; 745 746 out: 747 free(fp); 748 return r == 0 ? 0 : 1; 749 } 750 751 void 752 auth_debug_add(const char *fmt,...) 753 { 754 char buf[1024]; 755 va_list args; 756 757 if (!auth_debug_init) 758 return; 759 760 va_start(args, fmt); 761 vsnprintf(buf, sizeof(buf), fmt, args); 762 va_end(args); 763 buffer_put_cstring(&auth_debug, buf); 764 } 765 766 void 767 auth_debug_send(void) 768 { 769 char *msg; 770 771 if (!auth_debug_init) 772 return; 773 while (buffer_len(&auth_debug)) { 774 msg = buffer_get_string(&auth_debug, NULL); 775 packet_send_debug("%s", msg); 776 free(msg); 777 } 778 } 779 780 void 781 auth_debug_reset(void) 782 { 783 if (auth_debug_init) 784 buffer_clear(&auth_debug); 785 else { 786 buffer_init(&auth_debug); 787 auth_debug_init = 1; 788 } 789 } 790 791 struct passwd * 792 fakepw(void) 793 { 794 static struct passwd fake; 795 796 memset(&fake, 0, sizeof(fake)); 797 fake.pw_name = "NOUSER"; 798 fake.pw_passwd = 799 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK"; 800 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS 801 fake.pw_gecos = "NOUSER"; 802 #endif 803 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid; 804 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid; 805 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS 806 fake.pw_class = ""; 807 #endif 808 fake.pw_dir = "/nonexist"; 809 fake.pw_shell = "/nonexist"; 810 811 return (&fake); 812 } 813 814 /* 815 * Returns the remote DNS hostname as a string. The returned string must not 816 * be freed. NB. this will usually trigger a DNS query the first time it is 817 * called. 818 * This function does additional checks on the hostname to mitigate some 819 * attacks on legacy rhosts-style authentication. 820 * XXX is RhostsRSAAuthentication vulnerable to these? 821 * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?) 822 */ 823 824 static char * 825 remote_hostname(struct ssh *ssh) 826 { 827 struct sockaddr_storage from; 828 socklen_t fromlen; 829 struct addrinfo hints, *ai, *aitop; 830 char name[NI_MAXHOST], ntop2[NI_MAXHOST]; 831 const char *ntop = ssh_remote_ipaddr(ssh); 832 833 /* Get IP address of client. */ 834 fromlen = sizeof(from); 835 memset(&from, 0, sizeof(from)); 836 if (getpeername(ssh_packet_get_connection_in(ssh), 837 (struct sockaddr *)&from, &fromlen) < 0) { 838 debug("getpeername failed: %.100s", strerror(errno)); 839 return strdup(ntop); 840 } 841 842 ipv64_normalise_mapped(&from, &fromlen); 843 if (from.ss_family == AF_INET6) 844 fromlen = sizeof(struct sockaddr_in6); 845 846 debug3("Trying to reverse map address %.100s.", ntop); 847 /* Map the IP address to a host name. */ 848 if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), 849 NULL, 0, NI_NAMEREQD) != 0) { 850 /* Host name not found. Use ip address. */ 851 return strdup(ntop); 852 } 853 854 /* 855 * if reverse lookup result looks like a numeric hostname, 856 * someone is trying to trick us by PTR record like following: 857 * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 858 */ 859 memset(&hints, 0, sizeof(hints)); 860 hints.ai_socktype = SOCK_DGRAM; /*dummy*/ 861 hints.ai_flags = AI_NUMERICHOST; 862 if (getaddrinfo(name, NULL, &hints, &ai) == 0) { 863 logit("Nasty PTR record \"%s\" is set up for %s, ignoring", 864 name, ntop); 865 freeaddrinfo(ai); 866 return strdup(ntop); 867 } 868 869 /* Names are stored in lowercase. */ 870 lowercase(name); 871 872 /* 873 * Map it back to an IP address and check that the given 874 * address actually is an address of this host. This is 875 * necessary because anyone with access to a name server can 876 * define arbitrary names for an IP address. Mapping from 877 * name to IP address can be trusted better (but can still be 878 * fooled if the intruder has access to the name server of 879 * the domain). 880 */ 881 memset(&hints, 0, sizeof(hints)); 882 hints.ai_family = from.ss_family; 883 hints.ai_socktype = SOCK_STREAM; 884 if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { 885 logit("reverse mapping checking getaddrinfo for %.700s " 886 "[%s] failed.", name, ntop); 887 return strdup(ntop); 888 } 889 /* Look for the address from the list of addresses. */ 890 for (ai = aitop; ai; ai = ai->ai_next) { 891 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, 892 sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && 893 (strcmp(ntop, ntop2) == 0)) 894 break; 895 } 896 freeaddrinfo(aitop); 897 /* If we reached the end of the list, the address was not there. */ 898 if (ai == NULL) { 899 /* Address not found for the host name. */ 900 logit("Address %.100s maps to %.600s, but this does not " 901 "map back to the address.", ntop, name); 902 return strdup(ntop); 903 } 904 return strdup(name); 905 } 906 907 /* 908 * Return the canonical name of the host in the other side of the current 909 * connection. The host name is cached, so it is efficient to call this 910 * several times. 911 */ 912 913 const char * 914 auth_get_canonical_hostname(struct ssh *ssh, int use_dns) 915 { 916 static char *dnsname; 917 918 if (!use_dns) 919 return ssh_remote_ipaddr(ssh); 920 else if (dnsname != NULL) 921 return dnsname; 922 else { 923 dnsname = remote_hostname(ssh); 924 return dnsname; 925 } 926 } 927
