1 /* $OpenBSD: auth.c,v 1.162 2024/09/15 01:18:26 djm 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 #include <sys/wait.h> 32 33 #include <netinet/in.h> 34 35 #include <stdlib.h> 36 #include <errno.h> 37 #include <fcntl.h> 38 #ifdef HAVE_PATHS_H 39 # include <paths.h> 40 #endif 41 #include <pwd.h> 42 #ifdef HAVE_LOGIN_H 43 #include <login.h> 44 #endif 45 #ifdef USE_SHADOW 46 #include <shadow.h> 47 #endif 48 #include <stdarg.h> 49 #include <stdio.h> 50 #include <string.h> 51 #include <unistd.h> 52 #include <limits.h> 53 #include <netdb.h> 54 #include <time.h> 55 56 #include "xmalloc.h" 57 #include "match.h" 58 #include "groupaccess.h" 59 #include "log.h" 60 #include "sshbuf.h" 61 #include "misc.h" 62 #include "servconf.h" 63 #include "sshkey.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 "ssherr.h" 77 #include "channels.h" 78 #include "blacklist_client.h" 79 80 /* import */ 81 extern ServerOptions options; 82 extern struct include_list includes; 83 extern struct sshbuf *loginmsg; 84 extern struct passwd *privsep_pw; 85 extern struct sshauthopt *auth_opts; 86 87 /* Debugging messages */ 88 static struct sshbuf *auth_debug; 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 ssh *ssh, struct passwd * pw) 101 { 102 struct stat st; 103 const char *hostname = NULL, *ipaddr = NULL; 104 u_int i; 105 int r; 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 if (!options.use_pam && platform_locked_account(pw)) { 112 logit("User %.100s not allowed because account is locked", 113 pw->pw_name); 114 return 0; 115 } 116 117 /* 118 * Deny if shell does not exist or is not executable unless we 119 * are chrooting. 120 */ 121 if (options.chroot_directory == NULL || 122 strcasecmp(options.chroot_directory, "none") == 0) { 123 char *shell = xstrdup((pw->pw_shell[0] == '\0') ? 124 _PATH_BSHELL : pw->pw_shell); /* empty = /bin/sh */ 125 126 if (stat(shell, &st) == -1) { 127 logit("User %.100s not allowed because shell %.100s " 128 "does not exist", pw->pw_name, shell); 129 free(shell); 130 return 0; 131 } 132 if (S_ISREG(st.st_mode) == 0 || 133 (st.st_mode & (S_IXOTH|S_IXUSR|S_IXGRP)) == 0) { 134 logit("User %.100s not allowed because shell %.100s " 135 "is not executable", pw->pw_name, shell); 136 free(shell); 137 return 0; 138 } 139 free(shell); 140 } 141 142 if (options.num_deny_users > 0 || options.num_allow_users > 0 || 143 options.num_deny_groups > 0 || options.num_allow_groups > 0) { 144 hostname = auth_get_canonical_hostname(ssh, options.use_dns); 145 ipaddr = ssh_remote_ipaddr(ssh); 146 } 147 148 /* Return false if user is listed in DenyUsers */ 149 if (options.num_deny_users > 0) { 150 for (i = 0; i < options.num_deny_users; i++) { 151 r = match_user(pw->pw_name, hostname, ipaddr, 152 options.deny_users[i]); 153 if (r < 0) { 154 fatal("Invalid DenyUsers pattern \"%.100s\"", 155 options.deny_users[i]); 156 } else if (r != 0) { 157 logit("User %.100s from %.100s not allowed " 158 "because listed in DenyUsers", 159 pw->pw_name, hostname); 160 return 0; 161 } 162 } 163 } 164 /* Return false if AllowUsers isn't empty and user isn't listed there */ 165 if (options.num_allow_users > 0) { 166 for (i = 0; i < options.num_allow_users; i++) { 167 r = match_user(pw->pw_name, hostname, ipaddr, 168 options.allow_users[i]); 169 if (r < 0) { 170 fatal("Invalid AllowUsers pattern \"%.100s\"", 171 options.allow_users[i]); 172 } else if (r == 1) 173 break; 174 } 175 /* i < options.num_allow_users iff we break for loop */ 176 if (i >= options.num_allow_users) { 177 logit("User %.100s from %.100s not allowed because " 178 "not listed in AllowUsers", pw->pw_name, hostname); 179 return 0; 180 } 181 } 182 if (options.num_deny_groups > 0 || options.num_allow_groups > 0) { 183 /* Get the user's group access list (primary and supplementary) */ 184 if (ga_init(pw->pw_name, pw->pw_gid) == 0) { 185 logit("User %.100s from %.100s not allowed because " 186 "not in any group", pw->pw_name, hostname); 187 return 0; 188 } 189 190 /* Return false if one of user's groups is listed in DenyGroups */ 191 if (options.num_deny_groups > 0) 192 if (ga_match(options.deny_groups, 193 options.num_deny_groups)) { 194 ga_free(); 195 logit("User %.100s from %.100s not allowed " 196 "because a group is listed in DenyGroups", 197 pw->pw_name, hostname); 198 return 0; 199 } 200 /* 201 * Return false if AllowGroups isn't empty and one of user's groups 202 * isn't listed there 203 */ 204 if (options.num_allow_groups > 0) 205 if (!ga_match(options.allow_groups, 206 options.num_allow_groups)) { 207 ga_free(); 208 logit("User %.100s from %.100s not allowed " 209 "because none of user's groups are listed " 210 "in AllowGroups", pw->pw_name, hostname); 211 return 0; 212 } 213 ga_free(); 214 } 215 216 #ifdef CUSTOM_SYS_AUTH_ALLOWED_USER 217 if (!sys_auth_allowed_user(pw, loginmsg)) 218 return 0; 219 #endif 220 221 /* We found no reason not to let this user try to log on... */ 222 return 1; 223 } 224 225 /* 226 * Formats any key left in authctxt->auth_method_key for inclusion in 227 * auth_log()'s message. Also includes authxtct->auth_method_info if present. 228 */ 229 static char * 230 format_method_key(Authctxt *authctxt) 231 { 232 const struct sshkey *key = authctxt->auth_method_key; 233 const char *methinfo = authctxt->auth_method_info; 234 char *fp, *cafp, *ret = NULL; 235 236 if (key == NULL) 237 return NULL; 238 239 if (sshkey_is_cert(key)) { 240 fp = sshkey_fingerprint(key, 241 options.fingerprint_hash, SSH_FP_DEFAULT); 242 cafp = sshkey_fingerprint(key->cert->signature_key, 243 options.fingerprint_hash, SSH_FP_DEFAULT); 244 xasprintf(&ret, "%s %s ID %s (serial %llu) CA %s %s%s%s", 245 sshkey_type(key), fp == NULL ? "(null)" : fp, 246 key->cert->key_id, 247 (unsigned long long)key->cert->serial, 248 sshkey_type(key->cert->signature_key), 249 cafp == NULL ? "(null)" : cafp, 250 methinfo == NULL ? "" : ", ", 251 methinfo == NULL ? "" : methinfo); 252 free(fp); 253 free(cafp); 254 } else { 255 fp = sshkey_fingerprint(key, options.fingerprint_hash, 256 SSH_FP_DEFAULT); 257 xasprintf(&ret, "%s %s%s%s", sshkey_type(key), 258 fp == NULL ? "(null)" : fp, 259 methinfo == NULL ? "" : ", ", 260 methinfo == NULL ? "" : methinfo); 261 free(fp); 262 } 263 return ret; 264 } 265 266 void 267 auth_log(struct ssh *ssh, int authenticated, int partial, 268 const char *method, const char *submethod) 269 { 270 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 271 int level = SYSLOG_LEVEL_VERBOSE; 272 const char *authmsg; 273 char *extra = NULL; 274 275 if (!mm_is_monitor() && !authctxt->postponed) 276 return; 277 278 /* Raise logging level */ 279 if (authenticated == 1 || 280 !authctxt->valid || 281 authctxt->failures >= options.max_authtries / 2 || 282 strcmp(method, "password") == 0) 283 level = SYSLOG_LEVEL_INFO; 284 285 if (authctxt->postponed) 286 authmsg = "Postponed"; 287 else if (partial) 288 authmsg = "Partial"; 289 else { 290 authmsg = authenticated ? "Accepted" : "Failed"; 291 if (authenticated) 292 BLACKLIST_NOTIFY(ssh, BLACKLIST_AUTH_OK, 293 "Authenticated"); 294 } 295 296 if ((extra = format_method_key(authctxt)) == NULL) { 297 if (authctxt->auth_method_info != NULL) 298 extra = xstrdup(authctxt->auth_method_info); 299 } 300 301 do_log2(level, "%s %s%s%s for %s%.100s from %.200s port %d ssh2%s%s", 302 authmsg, 303 method, 304 submethod != NULL ? "/" : "", submethod == NULL ? "" : submethod, 305 authctxt->valid ? "" : "invalid user ", 306 authctxt->user, 307 ssh_remote_ipaddr(ssh), 308 ssh_remote_port(ssh), 309 extra != NULL ? ": " : "", 310 extra != NULL ? extra : ""); 311 312 free(extra); 313 314 #if defined(CUSTOM_FAILED_LOGIN) || defined(SSH_AUDIT_EVENTS) 315 if (authenticated == 0 && !(authctxt->postponed || partial)) { 316 /* Log failed login attempt */ 317 # ifdef CUSTOM_FAILED_LOGIN 318 if (strcmp(method, "password") == 0 || 319 strncmp(method, "keyboard-interactive", 20) == 0 || 320 strcmp(method, "challenge-response") == 0) 321 record_failed_login(ssh, authctxt->user, 322 auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); 323 # endif 324 # ifdef SSH_AUDIT_EVENTS 325 audit_event(ssh, audit_classify_auth(method)); 326 # endif 327 } 328 #endif 329 #if defined(CUSTOM_FAILED_LOGIN) && defined(WITH_AIXAUTHENTICATE) 330 if (authenticated) 331 sys_auth_record_login(authctxt->user, 332 auth_get_canonical_hostname(ssh, options.use_dns), "ssh", 333 loginmsg); 334 #endif 335 } 336 337 void 338 auth_maxtries_exceeded(struct ssh *ssh) 339 { 340 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 341 342 BLACKLIST_NOTIFY(ssh, BLACKLIST_AUTH_FAIL, "Maximum attempts exceeded"); 343 error("maximum authentication attempts exceeded for " 344 "%s%.100s from %.200s port %d ssh2", 345 authctxt->valid ? "" : "invalid user ", 346 authctxt->user, 347 ssh_remote_ipaddr(ssh), 348 ssh_remote_port(ssh)); 349 ssh_packet_disconnect(ssh, "Too many authentication failures"); 350 /* NOTREACHED */ 351 } 352 353 /* 354 * Check whether root logins are disallowed. 355 */ 356 int 357 auth_root_allowed(struct ssh *ssh, const char *method) 358 { 359 switch (options.permit_root_login) { 360 case PERMIT_YES: 361 return 1; 362 case PERMIT_NO_PASSWD: 363 if (strcmp(method, "publickey") == 0 || 364 strcmp(method, "hostbased") == 0 || 365 strcmp(method, "gssapi-with-mic") == 0) 366 return 1; 367 break; 368 case PERMIT_FORCED_ONLY: 369 if (auth_opts->force_command != NULL) { 370 logit("Root login accepted for forced command."); 371 return 1; 372 } 373 break; 374 } 375 logit("ROOT LOGIN REFUSED FROM %.200s port %d", 376 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 377 return 0; 378 } 379 380 381 /* 382 * Given a template and a passwd structure, build a filename 383 * by substituting % tokenised options. Currently, %% becomes '%', 384 * %h becomes the home directory and %u the username. 385 * 386 * This returns a buffer allocated by xmalloc. 387 */ 388 char * 389 expand_authorized_keys(const char *filename, struct passwd *pw) 390 { 391 char *file, uidstr[32], ret[PATH_MAX]; 392 int i; 393 394 snprintf(uidstr, sizeof(uidstr), "%llu", 395 (unsigned long long)pw->pw_uid); 396 file = percent_expand(filename, "h", pw->pw_dir, 397 "u", pw->pw_name, "U", uidstr, (char *)NULL); 398 399 /* 400 * Ensure that filename starts anchored. If not, be backward 401 * compatible and prepend the '%h/' 402 */ 403 if (path_absolute(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 } 412 413 char * 414 authorized_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 */ 422 HostStatus 423 check_key_in_hostfiles(struct passwd *pw, struct sshkey *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, 0); 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, 0); 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 host); 456 else if (host_status == HOST_OK) 457 debug_f("key for %s found at %s:%ld", 458 found->host, found->file, found->line); 459 else 460 debug_f("key for host %s not found", host); 461 462 free_hostkeys(hostkeys); 463 464 return host_status; 465 } 466 467 struct passwd * 468 getpwnamallow(struct ssh *ssh, const char *user) 469 { 470 #ifdef HAVE_LOGIN_CAP 471 extern login_cap_t *lc; 472 #ifdef HAVE_AUTH_HOSTOK 473 const char *from_host, *from_ip; 474 #endif 475 #ifdef BSD_AUTH 476 auth_session_t *as; 477 #endif 478 #endif 479 struct passwd *pw; 480 struct connection_info *ci; 481 u_int i; 482 483 ci = server_get_connection_info(ssh, 1, options.use_dns); 484 ci->user = user; 485 ci->user_invalid = getpwnam(user) == NULL; 486 parse_server_match_config(&options, &includes, ci); 487 log_change_level(options.log_level); 488 log_verbose_reset(); 489 for (i = 0; i < options.num_log_verbose; i++) 490 log_verbose_add(options.log_verbose[i]); 491 server_process_permitopen(ssh); 492 493 #if defined(_AIX) && defined(HAVE_SETAUTHDB) 494 aix_setauthdb(user); 495 #endif 496 497 pw = getpwnam(user); 498 499 #if defined(_AIX) && defined(HAVE_SETAUTHDB) 500 aix_restoreauthdb(); 501 #endif 502 if (pw == NULL) { 503 BLACKLIST_NOTIFY(ssh, BLACKLIST_AUTH_FAIL, "Invalid user"); 504 logit("Invalid user %.100s from %.100s port %d", 505 user, ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 506 #ifdef CUSTOM_FAILED_LOGIN 507 record_failed_login(ssh, user, 508 auth_get_canonical_hostname(ssh, options.use_dns), "ssh"); 509 #endif 510 #ifdef SSH_AUDIT_EVENTS 511 audit_event(ssh, SSH_INVALID_USER); 512 #endif /* SSH_AUDIT_EVENTS */ 513 return (NULL); 514 } 515 if (!allowed_user(ssh, pw)) 516 return (NULL); 517 #ifdef HAVE_LOGIN_CAP 518 if ((lc = login_getpwclass(pw)) == NULL) { 519 debug("unable to get login class: %s", user); 520 return (NULL); 521 } 522 #ifdef HAVE_AUTH_HOSTOK 523 from_host = auth_get_canonical_hostname(ssh, options.use_dns); 524 from_ip = ssh_remote_ipaddr(ssh); 525 if (!auth_hostok(lc, from_host, from_ip)) { 526 debug("Denied connection for %.200s from %.200s [%.200s].", 527 pw->pw_name, from_host, from_ip); 528 return (NULL); 529 } 530 #endif /* HAVE_AUTH_HOSTOK */ 531 #ifdef HAVE_AUTH_TIMEOK 532 if (!auth_timeok(lc, time(NULL))) { 533 debug("LOGIN %.200s REFUSED (TIME)", pw->pw_name); 534 return (NULL); 535 } 536 #endif /* HAVE_AUTH_TIMEOK */ 537 #ifdef BSD_AUTH 538 if ((as = auth_open()) == NULL || auth_setpwd(as, pw) != 0 || 539 auth_approval(as, lc, pw->pw_name, "ssh") <= 0) { 540 debug("Approval failure for %s", user); 541 pw = NULL; 542 } 543 if (as != NULL) 544 auth_close(as); 545 #endif 546 #endif 547 if (pw != NULL) 548 return (pwcopy(pw)); 549 return (NULL); 550 } 551 552 /* Returns 1 if key is revoked by revoked_keys_file, 0 otherwise */ 553 int 554 auth_key_is_revoked(struct sshkey *key) 555 { 556 char *fp = NULL; 557 int r; 558 559 if (options.revoked_keys_file == NULL) 560 return 0; 561 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 562 SSH_FP_DEFAULT)) == NULL) { 563 r = SSH_ERR_ALLOC_FAIL; 564 error_fr(r, "fingerprint key"); 565 goto out; 566 } 567 568 r = sshkey_check_revoked(key, options.revoked_keys_file); 569 switch (r) { 570 case 0: 571 break; /* not revoked */ 572 case SSH_ERR_KEY_REVOKED: 573 error("Authentication key %s %s revoked by file %s", 574 sshkey_type(key), fp, options.revoked_keys_file); 575 goto out; 576 default: 577 error_r(r, "Error checking authentication key %s %s in " 578 "revoked keys file %s", sshkey_type(key), fp, 579 options.revoked_keys_file); 580 goto out; 581 } 582 583 /* Success */ 584 r = 0; 585 586 out: 587 free(fp); 588 return r == 0 ? 0 : 1; 589 } 590 591 void 592 auth_debug_add(const char *fmt,...) 593 { 594 char buf[1024]; 595 va_list args; 596 int r; 597 598 va_start(args, fmt); 599 vsnprintf(buf, sizeof(buf), fmt, args); 600 va_end(args); 601 debug3("%s", buf); 602 if (auth_debug != NULL) 603 if ((r = sshbuf_put_cstring(auth_debug, buf)) != 0) 604 fatal_fr(r, "sshbuf_put_cstring"); 605 } 606 607 void 608 auth_debug_send(struct ssh *ssh) 609 { 610 char *msg; 611 int r; 612 613 if (auth_debug == NULL) 614 return; 615 while (sshbuf_len(auth_debug) != 0) { 616 if ((r = sshbuf_get_cstring(auth_debug, &msg, NULL)) != 0) 617 fatal_fr(r, "sshbuf_get_cstring"); 618 ssh_packet_send_debug(ssh, "%s", msg); 619 free(msg); 620 } 621 } 622 623 void 624 auth_debug_reset(void) 625 { 626 if (auth_debug != NULL) 627 sshbuf_reset(auth_debug); 628 else if ((auth_debug = sshbuf_new()) == NULL) 629 fatal_f("sshbuf_new failed"); 630 } 631 632 struct passwd * 633 fakepw(void) 634 { 635 static int done = 0; 636 static struct passwd fake; 637 const char hashchars[] = "./ABCDEFGHIJKLMNOPQRSTUVWXYZ" 638 "abcdefghijklmnopqrstuvwxyz0123456789"; /* from bcrypt.c */ 639 char *cp; 640 641 if (done) 642 return (&fake); 643 644 memset(&fake, 0, sizeof(fake)); 645 fake.pw_name = "NOUSER"; 646 fake.pw_passwd = xstrdup("$2a$10$" 647 "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"); 648 for (cp = fake.pw_passwd + 7; *cp != '\0'; cp++) 649 *cp = hashchars[arc4random_uniform(sizeof(hashchars) - 1)]; 650 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS 651 fake.pw_gecos = "NOUSER"; 652 #endif 653 fake.pw_uid = privsep_pw == NULL ? (uid_t)-1 : privsep_pw->pw_uid; 654 fake.pw_gid = privsep_pw == NULL ? (gid_t)-1 : privsep_pw->pw_gid; 655 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS 656 fake.pw_class = ""; 657 #endif 658 fake.pw_dir = "/nonexist"; 659 fake.pw_shell = "/nonexist"; 660 done = 1; 661 662 return (&fake); 663 } 664 665 /* 666 * Return the canonical name of the host in the other side of the current 667 * connection. The host name is cached, so it is efficient to call this 668 * several times. 669 */ 670 671 const char * 672 auth_get_canonical_hostname(struct ssh *ssh, int use_dns) 673 { 674 static char *dnsname; 675 676 if (!use_dns) 677 return ssh_remote_ipaddr(ssh); 678 if (dnsname != NULL) 679 return dnsname; 680 dnsname = ssh_remote_hostname(ssh); 681 return dnsname; 682 } 683 684 /* These functions link key/cert options to the auth framework */ 685 686 /* Log sshauthopt options locally and (optionally) for remote transmission */ 687 void 688 auth_log_authopts(const char *loc, const struct sshauthopt *opts, int do_remote) 689 { 690 int do_env = options.permit_user_env && opts->nenv > 0; 691 int do_permitopen = opts->npermitopen > 0 && 692 (options.allow_tcp_forwarding & FORWARD_LOCAL) != 0; 693 int do_permitlisten = opts->npermitlisten > 0 && 694 (options.allow_tcp_forwarding & FORWARD_REMOTE) != 0; 695 size_t i; 696 char msg[1024], buf[64]; 697 698 snprintf(buf, sizeof(buf), "%d", opts->force_tun_device); 699 /* Try to keep this alphabetically sorted */ 700 snprintf(msg, sizeof(msg), "key options:%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s", 701 opts->permit_agent_forwarding_flag ? " agent-forwarding" : "", 702 opts->force_command == NULL ? "" : " command", 703 do_env ? " environment" : "", 704 opts->valid_before == 0 ? "" : "expires", 705 opts->no_require_user_presence ? " no-touch-required" : "", 706 do_permitopen ? " permitopen" : "", 707 do_permitlisten ? " permitlisten" : "", 708 opts->permit_port_forwarding_flag ? " port-forwarding" : "", 709 opts->cert_principals == NULL ? "" : " principals", 710 opts->permit_pty_flag ? " pty" : "", 711 opts->require_verify ? " uv" : "", 712 opts->force_tun_device == -1 ? "" : " tun=", 713 opts->force_tun_device == -1 ? "" : buf, 714 opts->permit_user_rc ? " user-rc" : "", 715 opts->permit_x11_forwarding_flag ? " x11-forwarding" : ""); 716 717 debug("%s: %s", loc, msg); 718 if (do_remote) 719 auth_debug_add("%s: %s", loc, msg); 720 721 if (options.permit_user_env) { 722 for (i = 0; i < opts->nenv; i++) { 723 debug("%s: environment: %s", loc, opts->env[i]); 724 if (do_remote) { 725 auth_debug_add("%s: environment: %s", 726 loc, opts->env[i]); 727 } 728 } 729 } 730 731 /* Go into a little more details for the local logs. */ 732 if (opts->valid_before != 0) { 733 format_absolute_time(opts->valid_before, buf, sizeof(buf)); 734 debug("%s: expires at %s", loc, buf); 735 } 736 if (opts->cert_principals != NULL) { 737 debug("%s: authorized principals: \"%s\"", 738 loc, opts->cert_principals); 739 } 740 if (opts->force_command != NULL) 741 debug("%s: forced command: \"%s\"", loc, opts->force_command); 742 if (do_permitopen) { 743 for (i = 0; i < opts->npermitopen; i++) { 744 debug("%s: permitted open: %s", 745 loc, opts->permitopen[i]); 746 } 747 } 748 if (do_permitlisten) { 749 for (i = 0; i < opts->npermitlisten; i++) { 750 debug("%s: permitted listen: %s", 751 loc, opts->permitlisten[i]); 752 } 753 } 754 } 755 756 /* Activate a new set of key/cert options; merging with what is there. */ 757 int 758 auth_activate_options(struct ssh *ssh, struct sshauthopt *opts) 759 { 760 struct sshauthopt *old = auth_opts; 761 const char *emsg = NULL; 762 763 debug_f("setting new authentication options"); 764 if ((auth_opts = sshauthopt_merge(old, opts, &emsg)) == NULL) { 765 error("Inconsistent authentication options: %s", emsg); 766 return -1; 767 } 768 return 0; 769 } 770 771 /* Disable forwarding, etc for the session */ 772 void 773 auth_restrict_session(struct ssh *ssh) 774 { 775 struct sshauthopt *restricted; 776 777 debug_f("restricting session"); 778 779 /* A blank sshauthopt defaults to permitting nothing */ 780 if ((restricted = sshauthopt_new()) == NULL) 781 fatal_f("sshauthopt_new failed"); 782 restricted->permit_pty_flag = 1; 783 restricted->restricted = 1; 784 785 if (auth_activate_options(ssh, restricted) != 0) 786 fatal_f("failed to restrict session"); 787 sshauthopt_free(restricted); 788 } 789