1 /* $NetBSD: auth.c,v 1.40 2026/04/08 18:58:40 christos Exp $ */ 2 /* $OpenBSD: auth.c,v 1.164 2026/02/11 22:57:16 djm Exp $ */ 3 4 /* 5 * Copyright (c) 2000 Markus Friedl. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include "includes.h" 29 __RCSID("$NetBSD: auth.c,v 1.40 2026/04/08 18:58:40 christos Exp $"); 30 #include <sys/types.h> 31 #include <sys/stat.h> 32 #include <sys/socket.h> 33 #include <sys/wait.h> 34 35 #include <stdlib.h> 36 #include <errno.h> 37 #include <fcntl.h> 38 #include <login_cap.h> 39 #include <paths.h> 40 #include <pwd.h> 41 #include <stdarg.h> 42 #include <stdio.h> 43 #include <string.h> 44 #include <unistd.h> 45 #include <limits.h> 46 #include <netdb.h> 47 #include <time.h> 48 49 #include "xmalloc.h" 50 #include "match.h" 51 #include "groupaccess.h" 52 #include "log.h" 53 #include "sshbuf.h" 54 #include "misc.h" 55 #include "servconf.h" 56 #include "sshkey.h" 57 #include "hostfile.h" 58 #include "auth.h" 59 #include "auth-options.h" 60 #include "canohost.h" 61 #include "uidswap.h" 62 #include "packet.h" 63 #ifdef GSSAPI 64 #include "ssh-gss.h" 65 #endif 66 #include "authfile.h" 67 #include "monitor_wrap.h" 68 #include "ssherr.h" 69 #include "channels.h" 70 #include "pfilter.h" 71 72 #ifdef HAVE_LOGIN_CAP 73 #include <login_cap.h> 74 #endif 75 76 /* import */ 77 extern ServerOptions options; 78 extern struct include_list includes; 79 extern struct sshauthopt *auth_opts; 80 81 /* Debugging messages */ 82 static struct sshbuf *auth_debug; 83 84 #ifndef HOST_ONLY 85 /* 86 * Check if the user is allowed to log in via ssh. If user is listed 87 * in DenyUsers or one of user's groups is listed in DenyGroups, false 88 * will be returned. If AllowUsers isn't empty and user isn't listed 89 * there, or if AllowGroups isn't empty and one of user's groups isn't 90 * listed there, false will be returned. 91 * If the user's shell is not executable, false will be returned. 92 * Otherwise true is returned. 93 */ 94 int 95 allowed_user(struct ssh *ssh, struct passwd * pw) 96 { 97 #ifdef HAVE_LOGIN_CAP 98 extern login_cap_t *lc; 99 int match_name, match_ip; 100 char *cap_hlist, *hp; 101 #endif 102 struct stat st; 103 const char *hostname = NULL, *ipaddr = NULL; 104 int r; 105 u_int i; 106 107 /* Shouldn't be called if pw is NULL, but better safe than sorry... */ 108 if (!pw || !pw->pw_name) 109 return 0; 110 111 #ifdef HAVE_LOGIN_CAP 112 hostname = auth_get_canonical_hostname(ssh, options.use_dns); 113 ipaddr = ssh_remote_ipaddr(ssh); 114 115 lc = login_getclass(pw->pw_class); 116 117 /* 118 * Check the deny list. 119 */ 120 cap_hlist = login_getcapstr(lc, "host.deny", NULL, NULL); 121 if (cap_hlist != NULL) { 122 hp = strtok(cap_hlist, ","); 123 while (hp != NULL) { 124 match_name = match_hostname(hostname, hp); 125 match_ip = match_hostname(ipaddr, hp); 126 /* 127 * Only a positive match here causes a "deny". 128 */ 129 if (match_name > 0 || match_ip > 0) { 130 free(cap_hlist); 131 login_close(lc); 132 return 0; 133 } 134 hp = strtok(NULL, ","); 135 } 136 free(cap_hlist); 137 } 138 139 /* 140 * Check the allow list. If the allow list exists, and the 141 * remote host is not in it, the user is implicitly denied. 142 */ 143 cap_hlist = login_getcapstr(lc, "host.allow", NULL, NULL); 144 if (cap_hlist != NULL) { 145 hp = strtok(cap_hlist, ","); 146 if (hp == NULL) { 147 /* Just in case there's an empty string... */ 148 free(cap_hlist); 149 login_close(lc); 150 return 0; 151 } 152 while (hp != NULL) { 153 match_name = match_hostname(hostname, hp); 154 match_ip = match_hostname(ipaddr, hp); 155 /* 156 * Negative match causes an immediate "deny". 157 * Positive match causes us to break out 158 * of the loop (allowing a fallthrough). 159 */ 160 if (match_name < 0 || match_ip < 0) { 161 free(cap_hlist); 162 login_close(lc); 163 return 0; 164 } 165 if (match_name > 0 || match_ip > 0) 166 break; 167 hp = strtok(NULL, ","); 168 } 169 free(cap_hlist); 170 if (hp == NULL) { 171 login_close(lc); 172 return 0; 173 } 174 } 175 176 login_close(lc); 177 #endif 178 179 #ifdef USE_PAM 180 if (!options.use_pam) { 181 #endif 182 /* 183 * password/account expiration. 184 */ 185 if (pw->pw_change || pw->pw_expire) { 186 struct timeval tv; 187 188 (void)gettimeofday(&tv, (struct timezone *)NULL); 189 if (pw->pw_expire) { 190 if (tv.tv_sec >= pw->pw_expire) { 191 logit("User %.100s not allowed because account has expired", 192 pw->pw_name); 193 return 0; /* expired */ 194 } 195 } 196 #ifdef _PASSWORD_CHGNOW 197 if (pw->pw_change == _PASSWORD_CHGNOW) { 198 logit("User %.100s not allowed because password needs to be changed", 199 pw->pw_name); 200 201 return 0; /* can't force password change (yet) */ 202 } 203 #endif 204 if (pw->pw_change) { 205 if (tv.tv_sec >= pw->pw_change) { 206 logit("User %.100s not allowed because password has expired", 207 pw->pw_name); 208 return 0; /* expired */ 209 } 210 } 211 } 212 #ifdef USE_PAM 213 } 214 #endif 215 216 /* 217 * Deny if shell does not exist or is not executable unless we 218 * are chrooting. 219 */ 220 /* 221 * XXX Should check to see if it is executable by the 222 * XXX requesting user. --thorpej 223 */ 224 if (options.chroot_directory == NULL || 225 strcasecmp(options.chroot_directory, "none") == 0) { 226 char *shell = xstrdup((pw->pw_shell[0] == '\0') ? 227 _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */ 228 229 if (stat(shell, &st) == -1) { 230 logit("User %.100s not allowed because shell %.100s " 231 "does not exist", pw->pw_name, shell); 232 free(shell); 233 return 0; 234 } 235 if (S_ISREG(st.st_mode) == 0 || 236 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) { 237 logit("User %.100s not allowed because shell %.100s " 238 "is not executable", pw->pw_name, shell); 239 free(shell); 240 return 0; 241 } 242 free(shell); 243 } 244 /* 245 * XXX Consider nuking {Allow,Deny}{Users,Groups}. We have the 246 * XXX login_cap(3) mechanism which covers all other types of 247 * XXX logins, too. 248 */ 249 250 if (options.num_deny_users > 0 || options.num_allow_users > 0 || 251 options.num_deny_groups > 0 || options.num_allow_groups > 0) { 252 hostname = auth_get_canonical_hostname(ssh, options.use_dns); 253 ipaddr = ssh_remote_ipaddr(ssh); 254 } 255 256 /* Return false if user is listed in DenyUsers */ 257 if (options.num_deny_users > 0) { 258 for (i = 0; i < options.num_deny_users; i++) { 259 r = match_user(pw->pw_name, hostname, ipaddr, 260 options.deny_users[i]); 261 if (r < 0) { 262 fatal("Invalid DenyUsers pattern \"%.100s\"", 263 options.deny_users[i]); 264 } else if (r != 0) { 265 logit("User %.100s from %.100s not allowed " 266 "because listed in DenyUsers", 267 pw->pw_name, hostname); 268 return 0; 269 } 270 } 271 } 272 /* Return false if AllowUsers isn't empty and user isn't listed there */ 273 if (options.num_allow_users > 0) { 274 for (i = 0; i < options.num_allow_users; i++) { 275 r = match_user(pw->pw_name, hostname, ipaddr, 276 options.allow_users[i]); 277 if (r < 0) { 278 fatal("Invalid AllowUsers pattern \"%.100s\"", 279 options.allow_users[i]); 280 } else if (r == 1) 281 break; 282 } 283 /* i < options.num_allow_users iff we break for loop */ 284 if (i >= options.num_allow_users) { 285 logit("User %.100s from %.100s not allowed because " 286 "not listed in AllowUsers", pw->pw_name, hostname); 287 return 0; 288 } 289 } 290 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { 291 /* Get the user's group access list (primary and supplementary) */ 292 if (ga_init(pw->pw_name, pw->pw_gid) == 0) { 293 logit("User %.100s from %.100s not allowed because " 294 "not in any group", pw->pw_name, hostname); 295 return 0; 296 } 297 298 /* Return false if one of user's groups is listed in DenyGroups */ 299 if (options.num_deny_groups > 0) 300 if (ga_match(options.deny_groups, 301 options.num_deny_groups)) { 302 ga_free(); 303 logit("User %.100s from %.100s not allowed " 304 "because a group is listed in DenyGroups", 305 pw->pw_name, hostname); 306 return 0; 307 } 308 /* 309 * Return false if AllowGroups isn't empty and one of user's groups 310 * isn't listed there 311 */ 312 if (options.num_allow_groups > 0) 313 if (!ga_match(options.allow_groups, 314 options.num_allow_groups)) { 315 ga_free(); 316 logit("User %.100s from %.100s not allowed " 317 "because none of user's groups are listed " 318 "in AllowGroups", pw->pw_name, hostname); 319 return 0; 320 } 321 ga_free(); 322 } 323 /* We found no reason not to let this user try to log on... */ 324 return 1; 325 } 326 327 /* 328 * Formats any key left in authctxt->auth_method_key for inclusion in 329 * auth_log()'s message. Also includes authxtct->auth_method_info if present. 330 */ 331 static char * 332 format_method_key(Authctxt *authctxt) 333 { 334 const struct sshkey *key = authctxt->auth_method_key; 335 const char *methinfo = authctxt->auth_method_info; 336 char *fp, *cafp, *ret = NULL; 337 338 if (key == NULL) 339 return NULL; 340 341 if (sshkey_is_cert(key)) { 342 fp = sshkey_fingerprint(key, 343 options.fingerprint_hash, SSH_FP_DEFAULT); 344 cafp = sshkey_fingerprint(key->cert->signature_key, 345 options.fingerprint_hash, SSH_FP_DEFAULT); 346 xasprintf(&ret, "%s %s ID %s (serial %llu) CA %s %s%s%s", 347 sshkey_type(key), fp == NULL ? "(null)" : fp, 348 key->cert->key_id, 349 (unsigned long long)key->cert->serial, 350 sshkey_type(key->cert->signature_key), 351 cafp == NULL ? "(null)" : cafp, 352 methinfo == NULL ? "" : ", ", 353 methinfo == NULL ? "" : methinfo); 354 free(fp); 355 free(cafp); 356 } else { 357 fp = sshkey_fingerprint(key, options.fingerprint_hash, 358 SSH_FP_DEFAULT); 359 xasprintf(&ret, "%s %s%s%s", sshkey_type(key), 360 fp == NULL ? "(null)" : fp, 361 methinfo == NULL ? "" : ", ", 362 methinfo == NULL ? "" : methinfo); 363 free(fp); 364 } 365 return ret; 366 } 367 368 void 369 auth_log(struct ssh *ssh, int authenticated, int partial, 370 const char *method, const char *submethod) 371 { 372 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 373 int level = SYSLOG_LEVEL_VERBOSE; 374 const char *authmsg; 375 char *extra = NULL; 376 377 if (!mm_is_monitor() && !authctxt->postponed) 378 return; 379 380 /* Raise logging level */ 381 if (authenticated == 1 || 382 !authctxt->valid || 383 authctxt->failures >= options.max_authtries / 2 || 384 strcmp(method, "password") == 0) 385 level = SYSLOG_LEVEL_INFO; 386 387 if (authctxt->postponed) 388 authmsg = "Postponed"; 389 else if (partial) 390 authmsg = "Partial"; 391 else { 392 authmsg = authenticated ? "Accepted" : "Failed"; 393 if (authenticated) 394 pfilter_notify(0); 395 } 396 397 if ((extra = format_method_key(authctxt)) == NULL) { 398 if (authctxt->auth_method_info != NULL) 399 extra = xstrdup(authctxt->auth_method_info); 400 } 401 402 do_log2(level, "%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s", 403 authmsg, 404 method, 405 submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod, 406 authctxt->valid ? "" : "invalid user ", 407 authctxt->user, 408 ssh_remote_ipaddr(ssh), 409 ssh_remote_port(ssh), 410 extra != NULL ? ": " : "", 411 extra != NULL ? extra : ""); 412 413 free(extra); 414 } 415 416 void 417 auth_maxtries_exceeded(struct ssh *ssh) 418 { 419 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 420 421 pfilter_notify(1); 422 error("maximum authentication attempts exceeded for " 423 "%s%.100s from %.200s port %d ssh2", 424 authctxt->valid ? "" : "invalid user ", 425 authctxt->user, 426 ssh_remote_ipaddr(ssh), 427 ssh_remote_port(ssh)); 428 ssh_packet_disconnect(ssh, "Too many authentication failures"); 429 /* NOTREACHED */ 430 } 431 432 /* 433 * Check whether root logins are disallowed. 434 */ 435 int 436 auth_root_allowed(struct ssh *ssh, const char *method) 437 { 438 switch (options.permit_root_login) { 439 case PERMIT_YES: 440 return 1; 441 case PERMIT_NO_PASSWD: 442 if (strcmp(method, "publickey") == 0 || 443 strcmp(method, "hostbased") == 0 || 444 strcmp(method, "gssapi-with-mic") == 0) 445 return 1; 446 break; 447 case PERMIT_FORCED_ONLY: 448 if (auth_opts->force_command != NULL) { 449 logit("Root login accepted for forced command."); 450 return 1; 451 } 452 break; 453 } 454 logit("ROOT LOGIN REFUSED FROM %.200s port %d", 455 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 456 return 0; 457 } 458 459 460 /* 461 * Given a template and a passwd structure, build a filename 462 * by substituting % tokenised options. Currently, %% becomes '%', 463 * %h becomes the home directory and %u the username. 464 * 465 * This returns a buffer allocated by xmalloc. 466 */ 467 char * 468 expand_authorized_keys(const char *filename, struct passwd *pw) 469 { 470 char *file, uidstr[32], ret[PATH_MAX]; 471 int i; 472 473 snprintf(uidstr, sizeof(uidstr), "%llu", 474 (unsigned long long)pw->pw_uid); 475 file = percent_expand(filename, "h", pw->pw_dir, 476 "u", pw->pw_name, "U", uidstr, (char *)NULL); 477 478 /* 479 * Ensure that filename starts anchored. If not, be backward 480 * compatible and prepend the '%h/' 481 */ 482 if (path_absolute(file)) 483 return (file); 484 485 i = snprintf(ret, sizeof(ret), "%s/%s", pw->pw_dir, file); 486 if (i < 0 || (size_t)i >= sizeof(ret)) 487 fatal("expand_authorized_keys: path too long"); 488 free(file); 489 return (xstrdup(ret)); 490 } 491 492 char * 493 authorized_principals_file(struct passwd *pw) 494 { 495 if (options.authorized_principals_file == NULL) 496 return NULL; 497 return expand_authorized_keys(options.authorized_principals_file, pw); 498 } 499 500 /* return ok if key exists in sysfile or userfile */ 501 HostStatus 502 check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host, 503 const char *sysfile, const char *userfile) 504 { 505 char *user_hostfile; 506 struct stat st; 507 HostStatus host_status; 508 struct hostkeys *hostkeys; 509 const struct hostkey_entry *found; 510 511 hostkeys = init_hostkeys(); 512 load_hostkeys(hostkeys, host, sysfile, 0); 513 if (userfile != NULL) { 514 user_hostfile = tilde_expand_filename(userfile, pw->pw_uid); 515 if (options.strict_modes && 516 (stat(user_hostfile, &st) == 0) && 517 ((st.st_uid != 0 && st.st_uid != pw->pw_uid) || 518 (st.st_mode & 022) != 0)) { 519 logit("Authentication refused for %.100s: " 520 "bad owner or modes for %.200s", 521 pw->pw_name, user_hostfile); 522 auth_debug_add("Ignored %.200s: bad ownership or modes", 523 user_hostfile); 524 } else { 525 temporarily_use_uid(pw); 526 load_hostkeys(hostkeys, host, user_hostfile, 0); 527 restore_uid(); 528 } 529 free(user_hostfile); 530 } 531 host_status = check_key_in_hostkeys(hostkeys, key, &found); 532 if (host_status == HOST_REVOKED) 533 error("WARNING: revoked key for %s attempted authentication", 534 host); 535 else if (host_status == HOST_OK) 536 debug_f("key for %s found at %s:%ld", 537 found->host, found->file, found->line); 538 else 539 debug_f("key for host %s not found", host); 540 541 free_hostkeys(hostkeys); 542 543 return host_status; 544 } 545 546 struct passwd * 547 getpwnamallow(struct ssh *ssh, const char *user) 548 { 549 #ifdef HAVE_LOGIN_CAP 550 extern login_cap_t *lc; 551 #ifdef BSD_AUTH 552 auth_session_t *as; 553 #endif 554 #endif 555 struct passwd *pw; 556 struct connection_info *ci; 557 u_int i; 558 559 ci = server_get_connection_info(ssh, 1, options.use_dns); 560 ci->user = user; 561 ci->user_invalid = getpwnam(user) == NULL; 562 parse_server_match_config(&options, &includes, ci); 563 log_change_level(options.log_level); 564 log_verbose_reset(); 565 for (i = 0; i < options.num_log_verbose; i++) 566 log_verbose_add(options.log_verbose[i]); 567 server_process_permitopen(ssh); 568 569 pw = getpwnam(user); 570 if (pw == NULL) { 571 pfilter_notify(1); 572 logit("Invalid user %.100s from %.100s port %d", 573 user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 574 return (NULL); 575 } 576 if (!allowed_user(ssh, pw)) 577 return (NULL); 578 #ifdef HAVE_LOGIN_CAP 579 if ((lc = login_getclass(pw->pw_class)) == NULL) { 580 debug("unable to get login class: %s", user); 581 return (NULL); 582 } 583 #ifdef BSD_AUTH 584 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 || 585 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) { 586 debug("Approval failure for %s", user); 587 pw = NULL; 588 } 589 if (as != NULL) 590 auth_close(as); 591 #endif 592 #endif 593 if (pw != NULL) 594 return (pwcopy(pw)); 595 return (NULL); 596 } 597 598 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */ 599 int 600 auth_key_is_revoked(struct sshkey *key) 601 { 602 char *fp = NULL; 603 u_int i; 604 int r; 605 606 if (options.num_revoked_keys_files == 0) 607 return 0; 608 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 609 SSH_FP_DEFAULT)) == NULL) { 610 r = SSH_ERR_ALLOC_FAIL; 611 error_fr(r, "fingerprint key"); 612 goto out; 613 } 614 615 for (i = 0; i < options.num_revoked_keys_files; i++) { 616 r = sshkey_check_revoked(key, options.revoked_keys_files[i]); 617 switch (r) { 618 case 0: 619 break; /* not revoked */ 620 case SSH_ERR_KEY_REVOKED: 621 error("Authentication key %s %s revoked by file %s", 622 sshkey_type(key), fp, 623 options.revoked_keys_files[i]); 624 goto out; 625 default: 626 error_r(r, "Error checking authentication key %s %s in " 627 "revoked keys file %s", sshkey_type(key), fp, 628 options.revoked_keys_files[i]); 629 goto out; 630 } 631 } 632 633 /* Success */ 634 r = 0; 635 636 out: 637 free(fp); 638 return r == 0 ? 0 : 1; 639 } 640 #endif 641 642 void 643 auth_debug_add(const char *fmt,...) 644 { 645 char buf[1024]; 646 va_list args; 647 int r; 648 649 va_start(args, fmt); 650 vsnprintf(buf, sizeof(buf), fmt, args); 651 va_end(args); 652 debug3("%s", buf); 653 if (auth_debug != NULL) 654 if ((r = sshbuf_put_cstring(auth_debug, buf)) != 0) 655 fatal_fr(r, "sshbuf_put_cstring"); 656 } 657 658 void 659 auth_debug_send(struct ssh *ssh) 660 { 661 char *msg; 662 int r; 663 664 if (auth_debug == NULL) 665 return; 666 while (sshbuf_len(auth_debug) != 0) { 667 if ((r = sshbuf_get_cstring(auth_debug, &msg, NULL)) != 0) 668 fatal_fr(r, "sshbuf_get_cstring"); 669 ssh_packet_send_debug(ssh, "%s", msg); 670 free(msg); 671 } 672 } 673 674 void 675 auth_debug_reset(void) 676 { 677 if (auth_debug != NULL) 678 sshbuf_reset(auth_debug); 679 else if ((auth_debug = sshbuf_new()) == NULL) 680 fatal_f("sshbuf_new failed"); 681 } 682 683 struct passwd * 684 fakepw(void) 685 { 686 static int done = 0; 687 static struct passwd fake; 688 const char hashchars[] = "./ABCDEFGHIJKLMNOPQRSTUVWXYZ" 689 "abcdefghijklmnopqrstuvwxyz0123456789"; /* from bcrypt.c */ 690 char *cp; 691 692 if (done) 693 return (&fake); 694 695 memset(&fake, 0, sizeof(fake)); 696 fake.pw_name = __UNCONST("NOUSER"); 697 fake.pw_passwd = xstrdup("$2a$10$" 698 "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"); 699 for (cp = fake.pw_passwd + 7; *cp != '\0'; cp++) 700 *cp = hashchars[arc4random_uniform(sizeof(hashchars) - 1)]; 701 fake.pw_gecos = __UNCONST("NOUSER"); 702 fake.pw_uid = (uid_t)-1; 703 fake.pw_gid = (gid_t)-1; 704 fake.pw_class = __UNCONST(""); 705 fake.pw_dir = __UNCONST("/nonexist"); 706 fake.pw_shell = __UNCONST("/nonexist"); 707 done = 1; 708 709 return (&fake); 710 } 711 712 /* 713 * Return the canonical name of the host in the other side of the current 714 * connection. The host name is cached, so it is efficient to call this 715 * several times. 716 */ 717 718 const char * 719 auth_get_canonical_hostname(struct ssh *ssh, int use_dns) 720 { 721 static char *dnsname; 722 723 if (!use_dns) 724 return ssh_remote_ipaddr(ssh); 725 if (dnsname != NULL) 726 return dnsname; 727 dnsname = ssh_remote_hostname(ssh); 728 return dnsname; 729 } 730 731 /* These functions link key/cert options to the auth framework */ 732 733 /* Log sshauthopt options locally and (optionally) for remote transmission */ 734 void 735 auth_log_authopts(const char *loc, const struct sshauthopt *opts, int do_remote) 736 { 737 int do_env = options.permit_user_env && opts->nenv > 0; 738 int do_permitopen = opts->npermitopen > 0 && 739 (options.allow_tcp_forwarding & FORWARD_LOCAL) != 0; 740 int do_permitlisten = opts->npermitlisten > 0 && 741 (options.allow_tcp_forwarding & FORWARD_REMOTE) != 0; 742 size_t i; 743 char msg[1024], buf[64]; 744 745 snprintf(buf, sizeof(buf), "%d", opts->force_tun_device); 746 /* Try to keep this alphabetically sorted */ 747 snprintf(msg, sizeof(msg), "key options:%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s", 748 opts->permit_agent_forwarding_flag ? " agent-forwarding" : "", 749 opts->force_command == NULL ? "" : " command", 750 do_env ? " environment" : "", 751 opts->valid_before == 0 ? "" : "expires", 752 opts->no_require_user_presence ? " no-touch-required" : "", 753 do_permitopen ? " permitopen" : "", 754 do_permitlisten ? " permitlisten" : "", 755 opts->permit_port_forwarding_flag ? " port-forwarding" : "", 756 opts->cert_principals == NULL ? "" : " principals", 757 opts->permit_pty_flag ? " pty" : "", 758 opts->require_verify ? " uv" : "", 759 opts->force_tun_device == -1 ? "" : " tun=", 760 opts->force_tun_device == -1 ? "" : buf, 761 opts->permit_user_rc ? " user-rc" : "", 762 opts->permit_x11_forwarding_flag ? " x11-forwarding" : ""); 763 764 debug("%s: %s", loc, msg); 765 if (do_remote) 766 auth_debug_add("%s: %s", loc, msg); 767 768 if (options.permit_user_env) { 769 for (i = 0; i < opts->nenv; i++) { 770 debug("%s: environment: %s", loc, opts->env[i]); 771 if (do_remote) { 772 auth_debug_add("%s: environment: %s", 773 loc, opts->env[i]); 774 } 775 } 776 } 777 778 /* Go into a little more details for the local logs. */ 779 if (opts->valid_before != 0) { 780 format_absolute_time(opts->valid_before, buf, sizeof(buf)); 781 debug("%s: expires at %s", loc, buf); 782 } 783 if (opts->cert_principals != NULL) { 784 debug("%s: authorized principals: \"%s\"", 785 loc, opts->cert_principals); 786 } 787 if (opts->force_command != NULL) 788 debug("%s: forced command: \"%s\"", loc, opts->force_command); 789 if (do_permitopen) { 790 for (i = 0; i < opts->npermitopen; i++) { 791 debug("%s: permitted open: %s", 792 loc, opts->permitopen[i]); 793 } 794 } 795 if (do_permitlisten) { 796 for (i = 0; i < opts->npermitlisten; i++) { 797 debug("%s: permitted listen: %s", 798 loc, opts->permitlisten[i]); 799 } 800 } 801 } 802 803 /* Activate a new set of key/cert options; merging with what is there. */ 804 int 805 auth_activate_options(struct ssh *ssh, struct sshauthopt *opts) 806 { 807 struct sshauthopt *old = auth_opts; 808 const char *emsg = NULL; 809 810 debug_f("setting new authentication options"); 811 if ((auth_opts = sshauthopt_merge(old, opts, &emsg)) == NULL) { 812 error("Inconsistent authentication options: %s", emsg); 813 return -1; 814 } 815 sshauthopt_free(old); 816 return 0; 817 } 818 819 /* Disable forwarding, etc for the session */ 820 void 821 auth_restrict_session(struct ssh *ssh) 822 { 823 struct sshauthopt *restricted; 824 825 debug_f("restricting session"); 826 827 /* A blank sshauthopt defaults to permitting nothing */ 828 if ((restricted = sshauthopt_new()) == NULL) 829 fatal_f("sshauthopt_new failed"); 830 restricted->permit_pty_flag = 1; 831 restricted->restricted = 1; 832 833 if (auth_activate_options(ssh, restricted) != 0) 834 fatal_f("failed to restrict session"); 835 sshauthopt_free(restricted); 836 } 837
Indexes created Tue Jun 23 00:25:03 UTC 2026