auth.c revision 323124
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__RCSID("$FreeBSD: stable/10/crypto/openssh/auth.c 323124 2017-09-01 22:52:18Z des $"); 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 81/* import */ 82extern ServerOptions options; 83extern int use_privsep; 84extern Buffer loginmsg; 85extern struct passwd *privsep_pw; 86 87/* Debugging messages */ 88Buffer auth_debug; 89int auth_debug_init; 90 91/* 92 * Check if the user is allowed to log in via ssh. If user is listed 93 * in DenyUsers or one of user's groups is listed in DenyGroups, false 94 * will be returned. If AllowUsers isn't empty and user isn't listed 95 * there, or if AllowGroups isn't empty and one of user's groups isn't 96 * listed there, false will be returned. 97 * If the user's shell is not executable, false will be returned. 98 * Otherwise true is returned. 99 */ 100int 101allowed_user(struct passwd * pw) 102{ 103 struct ssh *ssh = active_state; /* XXX */ 104 struct stat st; 105 const char *hostname = NULL, *ipaddr = NULL, *passwd = NULL; 106 u_int i; 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 if (match_user(pw->pw_name, hostname, ipaddr, 197 options.deny_users[i])) { 198 logit("User %.100s from %.100s not allowed " 199 "because listed in DenyUsers", 200 pw->pw_name, hostname); 201 return 0; 202 } 203 } 204 /* Return false if AllowUsers isn't empty and user isn't listed there */ 205 if (options.num_allow_users > 0) { 206 for (i = 0; i < options.num_allow_users; i++) 207 if (match_user(pw->pw_name, hostname, ipaddr, 208 options.allow_users[i])) 209 break; 210 /* i < options.num_allow_users iff we break for loop */ 211 if (i >= options.num_allow_users) { 212 logit("User %.100s from %.100s not allowed because " 213 "not listed in AllowUsers", pw->pw_name, hostname); 214 return 0; 215 } 216 } 217 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { 218 /* Get the user's group access list (primary and supplementary) */ 219 if (ga_init(pw->pw_name, pw->pw_gid) == 0) { 220 logit("User %.100s from %.100s not allowed because " 221 "not in any group", pw->pw_name, hostname); 222 return 0; 223 } 224 225 /* Return false if one of user's groups is listed in DenyGroups */ 226 if (options.num_deny_groups > 0) 227 if (ga_match(options.deny_groups, 228 options.num_deny_groups)) { 229 ga_free(); 230 logit("User %.100s from %.100s not allowed " 231 "because a group is listed in DenyGroups", 232 pw->pw_name, hostname); 233 return 0; 234 } 235 /* 236 * Return false if AllowGroups isn't empty and one of user's groups 237 * isn't listed there 238 */ 239 if (options.num_allow_groups > 0) 240 if (!ga_match(options.allow_groups, 241 options.num_allow_groups)) { 242 ga_free(); 243 logit("User %.100s from %.100s not allowed " 244 "because none of user's groups are listed " 245 "in AllowGroups", pw->pw_name, hostname); 246 return 0; 247 } 248 ga_free(); 249 } 250 251#ifdef CUSTOM_SYS_AUTH_ALLOWED_USER 252 if (!sys_auth_allowed_user(pw, &loginmsg)) 253 return 0; 254#endif 255 256 /* We found no reason not to let this user try to log on... */ 257 return 1; 258} 259 260void 261auth_info(Authctxt *authctxt, const char *fmt, ...) 262{ 263 va_list ap; 264 int i; 265 266 free(authctxt->info); 267 authctxt->info = NULL; 268 269 va_start(ap, fmt); 270 i = vasprintf(&authctxt->info, fmt, ap); 271 va_end(ap); 272 273 if (i < 0 || authctxt->info == NULL) 274 fatal("vasprintf failed"); 275} 276 277void 278auth_log(Authctxt *authctxt, int authenticated, int partial, 279 const char *method, const char *submethod) 280{ 281 struct ssh *ssh = active_state; /* XXX */ 282 void (*authlog) (const char *fmt,...) = verbose; 283 char *authmsg; 284 285 if (use_privsep && !mm_is_monitor() && !authctxt->postponed) 286 return; 287 288 /* Raise logging level */ 289 if (authenticated == 1 || 290 !authctxt->valid || 291 authctxt->failures >= options.max_authtries / 2 || 292 strcmp(method, "password") == 0) 293 authlog = logit; 294 295 if (authctxt->postponed) 296 authmsg = "Postponed"; 297 else if (partial) 298 authmsg = "Partial"; 299 else 300 authmsg = authenticated ? "Accepted" : "Failed"; 301 302 authlog("%s %s%s%s for %s%.100s from %.200s port %d %s%s%s", 303 authmsg, 304 method, 305 submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod, 306 authctxt->valid ? "" : "invalid user ", 307 authctxt->user, 308 ssh_remote_ipaddr(ssh), 309 ssh_remote_port(ssh), 310 compat20 ? "ssh2" : "ssh1", 311 authctxt->info != NULL ? ": " : "", 312 authctxt->info != NULL ? authctxt->info : ""); 313 free(authctxt->info); 314 authctxt->info = NULL; 315 316#ifdef CUSTOM_FAILED_LOGIN 317 if (authenticated == 0 && !authctxt->postponed && 318 (strcmp(method, "password") == 0 || 319 strncmp(method, "keyboard-interactive", 20) == 0 || 320 strcmp(method, "challenge-response") == 0)) 321 record_failed_login(authctxt->user, 322 auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); 323# ifdef WITH_AIXAUTHENTICATE 324 if (authenticated) 325 sys_auth_record_login(authctxt->user, 326 auth_get_canonical_hostname(ssh, options.use_dns), "ssh", 327 &loginmsg); 328# endif 329#endif 330#ifdef SSH_AUDIT_EVENTS 331 if (authenticated == 0 && !authctxt->postponed) 332 audit_event(audit_classify_auth(method)); 333#endif 334} 335 336 337void 338auth_maxtries_exceeded(Authctxt *authctxt) 339{ 340 struct ssh *ssh = active_state; /* XXX */ 341 342 error("maximum authentication attempts exceeded for " 343 "%s%.100s from %.200s port %d %s", 344 authctxt->valid ? "" : "invalid user ", 345 authctxt->user, 346 ssh_remote_ipaddr(ssh), 347 ssh_remote_port(ssh), 348 compat20 ? "ssh2" : "ssh1"); 349 packet_disconnect("Too many authentication failures"); 350 /* NOTREACHED */ 351} 352 353/* 354 * Check whether root logins are disallowed. 355 */ 356int 357auth_root_allowed(const char *method) 358{ 359 struct ssh *ssh = active_state; /* XXX */ 360 361 switch (options.permit_root_login) { 362 case PERMIT_YES: 363 return 1; 364 case PERMIT_NO_PASSWD: 365 if (strcmp(method, "publickey") == 0 || 366 strcmp(method, "hostbased") == 0 || 367 strcmp(method, "gssapi-with-mic") == 0) 368 return 1; 369 break; 370 case PERMIT_FORCED_ONLY: 371 if (forced_command) { 372 logit("Root login accepted for forced command."); 373 return 1; 374 } 375 break; 376 } 377 logit("ROOT LOGIN REFUSED FROM %.200s port %d", 378 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 379 return 0; 380} 381 382 383/* 384 * Given a template and a passwd structure, build a filename 385 * by substituting % tokenised options. Currently, %% becomes '%', 386 * %h becomes the home directory and %u the username. 387 * 388 * This returns a buffer allocated by xmalloc. 389 */ 390char * 391expand_authorized_keys(const char *filename, struct passwd *pw) 392{ 393 char *file, ret[PATH_MAX]; 394 int i; 395 396 file = percent_expand(filename, "h", pw->pw_dir, 397 "u", pw->pw_name, (char *)NULL); 398 399 /* 400 * Ensure that filename starts anchored. If not, be backward 401 * compatible and prepend the '%h/' 402 */ 403 if (*file == '/') 404 return (file); 405 406 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file); 407 if (i < 0 || (size_t)i >= sizeof(ret)) 408 fatal("expand_authorized_keys: path too long"); 409 free(file); 410 return (xstrdup(ret)); 411} 412 413char * 414authorized_principals_file(struct passwd *pw) 415{ 416 if (options.authorized_principals_file == NULL) 417 return NULL; 418 return expand_authorized_keys(options.authorized_principals_file, pw); 419} 420 421/* return ok if key exists in sysfile or userfile */ 422HostStatus 423check_key_in_hostfiles(struct passwd *pw, Key *key, const char *host, 424 const char *sysfile, const char *userfile) 425{ 426 char *user_hostfile; 427 struct stat st; 428 HostStatus host_status; 429 struct hostkeys *hostkeys; 430 const struct hostkey_entry *found; 431 432 hostkeys = init_hostkeys(); 433 load_hostkeys(hostkeys, host, sysfile); 434 if (userfile != NULL) { 435 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid); 436 if (options.strict_modes && 437 (stat(user_hostfile, &st) == 0) && 438 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || 439 (st.st_mode & 022) != 0)) { 440 logit("Authentication refused for %.100s: " 441 "bad owner or modes for %.200s", 442 pw->pw_name, user_hostfile); 443 auth_debug_add("Ignored %.200s: bad ownership or modes", 444 user_hostfile); 445 } else { 446 temporarily_use_uid(pw); 447 load_hostkeys(hostkeys, host, user_hostfile); 448 restore_uid(); 449 } 450 free(user_hostfile); 451 } 452 host_status = check_key_in_hostkeys(hostkeys, key, &found); 453 if (host_status == HOST_REVOKED) 454 error("WARNING: revoked key for %s attempted authentication", 455 found->host); 456 else if (host_status == HOST_OK) 457 debug("%s: key for %s found at %s:%ld", __func__, 458 found->host, found->file, found->line); 459 else 460 debug("%s: key for host %s not found", __func__, host); 461 462 free_hostkeys(hostkeys); 463 464 return host_status; 465} 466 467/* 468 * Check a given path for security. This is defined as all components 469 * of the path to the file must be owned by either the owner of 470 * of the file or root and no directories must be group or world writable. 471 * 472 * XXX Should any specific check be done for sym links ? 473 * 474 * Takes a file name, its stat information (preferably from fstat() to 475 * avoid races), the uid of the expected owner, their home directory and an 476 * error buffer plus max size as arguments. 477 * 478 * Returns 0 on success and -1 on failure 479 */ 480int 481auth_secure_path(const char *name, struct stat *stp, const char *pw_dir, 482 uid_t uid, char *err, size_t errlen) 483{ 484 char buf[PATH_MAX], homedir[PATH_MAX]; 485 char *cp; 486 int comparehome = 0; 487 struct stat st; 488 489 if (realpath(name, buf) == NULL) { 490 snprintf(err, errlen, "realpath %s failed: %s", name, 491 strerror(errno)); 492 return -1; 493 } 494 if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL) 495 comparehome = 1; 496 497 if (!S_ISREG(stp->st_mode)) { 498 snprintf(err, errlen, "%s is not a regular file", buf); 499 return -1; 500 } 501 if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) || 502 (stp->st_mode & 022) != 0) { 503 snprintf(err, errlen, "bad ownership or modes for file %s", 504 buf); 505 return -1; 506 } 507 508 /* for each component of the canonical path, walking upwards */ 509 for (;;) { 510 if ((cp = dirname(buf)) == NULL) { 511 snprintf(err, errlen, "dirname() failed"); 512 return -1; 513 } 514 strlcpy(buf, cp, sizeof(buf)); 515 516 if (stat(buf, &st) < 0 || 517 (!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) || 518 (st.st_mode & 022) != 0) { 519 snprintf(err, errlen, 520 "bad ownership or modes for directory %s", buf); 521 return -1; 522 } 523 524 /* If are past the homedir then we can stop */ 525 if (comparehome && strcmp(homedir, buf) == 0) 526 break; 527 528 /* 529 * dirname should always complete with a "/" path, 530 * but we can be paranoid and check for "." too 531 */ 532 if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0)) 533 break; 534 } 535 return 0; 536} 537 538/* 539 * Version of secure_path() that accepts an open file descriptor to 540 * avoid races. 541 * 542 * Returns 0 on success and -1 on failure 543 */ 544static int 545secure_filename(FILE *f, const char *file, struct passwd *pw, 546 char *err, size_t errlen) 547{ 548 struct stat st; 549 550 /* check the open file to avoid races */ 551 if (fstat(fileno(f), &st) < 0) { 552 snprintf(err, errlen, "cannot stat file %s: %s", 553 file, strerror(errno)); 554 return -1; 555 } 556 return auth_secure_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen); 557} 558 559static FILE * 560auth_openfile(const char *file, struct passwd *pw, int strict_modes, 561 int log_missing, char *file_type) 562{ 563 char line[1024]; 564 struct stat st; 565 int fd; 566 FILE *f; 567 568 if ((fd = open(file, O_RDONLY|O_NONBLOCK)) == -1) { 569 if (log_missing || errno != ENOENT) 570 debug("Could not open %s '%s': %s", file_type, file, 571 strerror(errno)); 572 return NULL; 573 } 574 575 if (fstat(fd, &st) < 0) { 576 close(fd); 577 return NULL; 578 } 579 if (!S_ISREG(st.st_mode)) { 580 logit("User %s %s %s is not a regular file", 581 pw->pw_name, file_type, file); 582 close(fd); 583 return NULL; 584 } 585 unset_nonblock(fd); 586 if ((f = fdopen(fd, "r")) == NULL) { 587 close(fd); 588 return NULL; 589 } 590 if (strict_modes && 591 secure_filename(f, file, pw, line, sizeof(line)) != 0) { 592 fclose(f); 593 logit("Authentication refused: %s", line); 594 auth_debug_add("Ignored %s: %s", file_type, line); 595 return NULL; 596 } 597 598 return f; 599} 600 601 602FILE * 603auth_openkeyfile(const char *file, struct passwd *pw, int strict_modes) 604{ 605 return auth_openfile(file, pw, strict_modes, 1, "authorized keys"); 606} 607 608FILE * 609auth_openprincipals(const char *file, struct passwd *pw, int strict_modes) 610{ 611 return auth_openfile(file, pw, strict_modes, 0, 612 "authorized principals"); 613} 614 615struct passwd * 616getpwnamallow(const char *user) 617{ 618 struct ssh *ssh = active_state; /* XXX */ 619#ifdef HAVE_LOGIN_CAP 620 extern login_cap_t *lc; 621#ifdef BSD_AUTH 622 auth_session_t *as; 623#endif 624#endif 625 struct passwd *pw; 626 struct connection_info *ci = get_connection_info(1, options.use_dns); 627 628 ci->user = user; 629 parse_server_match_config(&options, ci); 630 631#if defined(_AIX) && defined(HAVE_SETAUTHDB) 632 aix_setauthdb(user); 633#endif 634 635 pw = getpwnam(user); 636 637#if defined(_AIX) && defined(HAVE_SETAUTHDB) 638 aix_restoreauthdb(); 639#endif 640#ifdef HAVE_CYGWIN 641 /* 642 * Windows usernames are case-insensitive. To avoid later problems 643 * when trying to match the username, the user is only allowed to 644 * login if the username is given in the same case as stored in the 645 * user database. 646 */ 647 if (pw != NULL && strcmp(user, pw->pw_name) != 0) { 648 logit("Login name %.100s does not match stored username %.100s", 649 user, pw->pw_name); 650 pw = NULL; 651 } 652#endif 653 if (pw == NULL) { 654 logit("Invalid user %.100s from %.100s port %d", 655 user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 656#ifdef CUSTOM_FAILED_LOGIN 657 record_failed_login(user, 658 auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); 659#endif 660#ifdef SSH_AUDIT_EVENTS 661 audit_event(SSH_INVALID_USER); 662#endif /* SSH_AUDIT_EVENTS */ 663 return (NULL); 664 } 665 if (!allowed_user(pw)) 666 return (NULL); 667#ifdef HAVE_LOGIN_CAP 668 if ((lc = login_getpwclass(pw)) == NULL) { 669 debug("unable to get login class: %s", user); 670 return (NULL); 671 } 672#ifdef BSD_AUTH 673 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 || 674 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) { 675 debug("Approval failure for %s", user); 676 pw = NULL; 677 } 678 if (as != NULL) 679 auth_close(as); 680#endif 681#endif 682 if (pw != NULL) 683 return (pwcopy(pw)); 684 return (NULL); 685} 686 687/* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */ 688int 689auth_key_is_revoked(Key *key) 690{ 691 char *fp = NULL; 692 int r; 693 694 if (options.revoked_keys_file == NULL) 695 return 0; 696 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 697 SSH_FP_DEFAULT)) == NULL) { 698 r = SSH_ERR_ALLOC_FAIL; 699 error("%s: fingerprint key: %s", __func__, ssh_err(r)); 700 goto out; 701 } 702 703 r = sshkey_check_revoked(key, options.revoked_keys_file); 704 switch (r) { 705 case 0: 706 break; /* not revoked */ 707 case SSH_ERR_KEY_REVOKED: 708 error("Authentication key %s %s revoked by file %s", 709 sshkey_type(key), fp, options.revoked_keys_file); 710 goto out; 711 default: 712 error("Error checking authentication key %s %s in " 713 "revoked keys file %s: %s", sshkey_type(key), fp, 714 options.revoked_keys_file, ssh_err(r)); 715 goto out; 716 } 717 718 /* Success */ 719 r = 0; 720 721 out: 722 free(fp); 723 return r == 0 ? 0 : 1; 724} 725 726void 727auth_debug_add(const char *fmt,...) 728{ 729 char buf[1024]; 730 va_list args; 731 732 if (!auth_debug_init) 733 return; 734 735 va_start(args, fmt); 736 vsnprintf(buf, sizeof(buf), fmt, args); 737 va_end(args); 738 buffer_put_cstring(&auth_debug, buf); 739} 740 741void 742auth_debug_send(void) 743{ 744 char *msg; 745 746 if (!auth_debug_init) 747 return; 748 while (buffer_len(&auth_debug)) { 749 msg = buffer_get_string(&auth_debug, NULL); 750 packet_send_debug("%s", msg); 751 free(msg); 752 } 753} 754 755void 756auth_debug_reset(void) 757{ 758 if (auth_debug_init) 759 buffer_clear(&auth_debug); 760 else { 761 buffer_init(&auth_debug); 762 auth_debug_init = 1; 763 } 764} 765 766struct passwd * 767fakepw(void) 768{ 769 static struct passwd fake; 770 771 memset(&fake, 0, sizeof(fake)); 772 fake.pw_name = "NOUSER"; 773 fake.pw_passwd = 774 "$2a$06$r3.juUaHZDlIbQaO2dS9FuYxL1W9M81R1Tc92PoSNmzvpEqLkLGrK"; 775#ifdef HAVE_STRUCT_PASSWD_PW_GECOS 776 fake.pw_gecos = "NOUSER"; 777#endif 778 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid; 779 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid; 780#ifdef HAVE_STRUCT_PASSWD_PW_CLASS 781 fake.pw_class = ""; 782#endif 783 fake.pw_dir = "/nonexist"; 784 fake.pw_shell = "/nonexist"; 785 786 return (&fake); 787} 788 789/* 790 * Returns the remote DNS hostname as a string. The returned string must not 791 * be freed. NB. this will usually trigger a DNS query the first time it is 792 * called. 793 * This function does additional checks on the hostname to mitigate some 794 * attacks on legacy rhosts-style authentication. 795 * XXX is RhostsRSAAuthentication vulnerable to these? 796 * XXX Can we remove these checks? (or if not, remove RhostsRSAAuthentication?) 797 */ 798 799static char * 800remote_hostname(struct ssh *ssh) 801{ 802 struct sockaddr_storage from; 803 socklen_t fromlen; 804 struct addrinfo hints, *ai, *aitop; 805 char name[NI_MAXHOST], ntop2[NI_MAXHOST]; 806 const char *ntop = ssh_remote_ipaddr(ssh); 807 808 /* Get IP address of client. */ 809 fromlen = sizeof(from); 810 memset(&from, 0, sizeof(from)); 811 if (getpeername(ssh_packet_get_connection_in(ssh), 812 (struct sockaddr *)&from, &fromlen) < 0) { 813 debug("getpeername failed: %.100s", strerror(errno)); 814 return strdup(ntop); 815 } 816 817 ipv64_normalise_mapped(&from, &fromlen); 818 if (from.ss_family == AF_INET6) 819 fromlen = sizeof(struct sockaddr_in6); 820 821 debug3("Trying to reverse map address %.100s.", ntop); 822 /* Map the IP address to a host name. */ 823 if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name), 824 NULL, 0, NI_NAMEREQD) != 0) { 825 /* Host name not found. Use ip address. */ 826 return strdup(ntop); 827 } 828 829 /* 830 * if reverse lookup result looks like a numeric hostname, 831 * someone is trying to trick us by PTR record like following: 832 * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 833 */ 834 memset(&hints, 0, sizeof(hints)); 835 hints.ai_socktype = SOCK_DGRAM; /*dummy*/ 836 hints.ai_flags = AI_NUMERICHOST; 837 if (getaddrinfo(name, NULL, &hints, &ai) == 0) { 838 logit("Nasty PTR record \"%s\" is set up for %s, ignoring", 839 name, ntop); 840 freeaddrinfo(ai); 841 return strdup(ntop); 842 } 843 844 /* Names are stored in lowercase. */ 845 lowercase(name); 846 847 /* 848 * Map it back to an IP address and check that the given 849 * address actually is an address of this host. This is 850 * necessary because anyone with access to a name server can 851 * define arbitrary names for an IP address. Mapping from 852 * name to IP address can be trusted better (but can still be 853 * fooled if the intruder has access to the name server of 854 * the domain). 855 */ 856 memset(&hints, 0, sizeof(hints)); 857 hints.ai_family = from.ss_family; 858 hints.ai_socktype = SOCK_STREAM; 859 if (getaddrinfo(name, NULL, &hints, &aitop) != 0) { 860 logit("reverse mapping checking getaddrinfo for %.700s " 861 "[%s] failed.", name, ntop); 862 return strdup(ntop); 863 } 864 /* Look for the address from the list of addresses. */ 865 for (ai = aitop; ai; ai = ai->ai_next) { 866 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2, 867 sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 && 868 (strcmp(ntop, ntop2) == 0)) 869 break; 870 } 871 freeaddrinfo(aitop); 872 /* If we reached the end of the list, the address was not there. */ 873 if (ai == NULL) { 874 /* Address not found for the host name. */ 875 logit("Address %.100s maps to %.600s, but this does not " 876 "map back to the address.", ntop, name); 877 return strdup(ntop); 878 } 879 return strdup(name); 880} 881 882/* 883 * Return the canonical name of the host in the other side of the current 884 * connection. The host name is cached, so it is efficient to call this 885 * several times. 886 */ 887 888const char * 889auth_get_canonical_hostname(struct ssh *ssh, int use_dns) 890{ 891 static char *dnsname; 892 893 if (!use_dns) 894 return ssh_remote_ipaddr(ssh); 895 else if (dnsname != NULL) 896 return dnsname; 897 else { 898 dnsname = remote_hostname(ssh); 899 return dnsname; 900 } 901} 902