1 /* $NetBSD: sshd.c,v 1.47 2022/10/05 22:39:36 christos Exp $ */ 2 /* $OpenBSD: sshd.c,v 1.591 2022/09/17 10:34:29 djm Exp $ */ 3 4 /* 5 * Author: Tatu Ylonen <ylo@cs.hut.fi> 6 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 7 * All rights reserved 8 * This program is the ssh daemon. It listens for connections from clients, 9 * and performs authentication, executes use commands or shell, and forwards 10 * information to/from the application to the user client over an encrypted 11 * connection. This can also handle forwarding of X11, TCP/IP, and 12 * authentication agent connections. 13 * 14 * As far as I am concerned, the code I have written for this software 15 * can be used freely for any purpose. Any derived versions of this 16 * software must be clearly marked as such, and if the derived work is 17 * incompatible with the protocol description in the RFC file, it must be 18 * called by a name other than "ssh" or "Secure Shell". 19 * 20 * SSH2 implementation: 21 * Privilege Separation: 22 * 23 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 24 * Copyright (c) 2002 Niels Provos. All rights reserved. 25 * 26 * Redistribution and use in source and binary forms, with or without 27 * modification, are permitted provided that the following conditions 28 * are met: 29 * 1. Redistributions of source code must retain the above copyright 30 * notice, this list of conditions and the following disclaimer. 31 * 2. Redistributions in binary form must reproduce the above copyright 32 * notice, this list of conditions and the following disclaimer in the 33 * documentation and/or other materials provided with the distribution. 34 * 35 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 36 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 37 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 38 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 39 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 40 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 41 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 42 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 43 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 44 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 45 */ 46 47 #include "includes.h" 48 __RCSID("$NetBSD: sshd.c,v 1.47 2022/10/05 22:39:36 christos Exp $"); 49 #include <sys/types.h> 50 #include <sys/param.h> 51 #include <sys/ioctl.h> 52 #include <sys/wait.h> 53 #include <sys/tree.h> 54 #include <sys/stat.h> 55 #include <sys/socket.h> 56 #include <sys/time.h> 57 #include <sys/queue.h> 58 59 #include <errno.h> 60 #include <fcntl.h> 61 #include <netdb.h> 62 #include <paths.h> 63 #include <poll.h> 64 #include <pwd.h> 65 #include <signal.h> 66 #include <stdio.h> 67 #include <stdlib.h> 68 #include <string.h> 69 #include <stdarg.h> 70 #include <unistd.h> 71 #include <limits.h> 72 73 #ifdef WITH_OPENSSL 74 #include <openssl/bn.h> 75 #endif 76 77 #include "xmalloc.h" 78 #include "ssh.h" 79 #include "ssh2.h" 80 #include "sshpty.h" 81 #include "packet.h" 82 #include "log.h" 83 #include "sshbuf.h" 84 #include "misc.h" 85 #include "match.h" 86 #include "servconf.h" 87 #include "uidswap.h" 88 #include "compat.h" 89 #include "cipher.h" 90 #include "digest.h" 91 #include "sshkey.h" 92 #include "kex.h" 93 #include "myproposal.h" 94 #include "authfile.h" 95 #include "pathnames.h" 96 #include "atomicio.h" 97 #include "canohost.h" 98 #include "hostfile.h" 99 #include "auth.h" 100 #include "authfd.h" 101 #include "misc.h" 102 #include "msg.h" 103 #include "dispatch.h" 104 #include "channels.h" 105 #include "session.h" 106 #include "monitor.h" 107 #ifdef GSSAPI 108 #include "ssh-gss.h" 109 #endif 110 #include "monitor_wrap.h" 111 #include "ssh-sandbox.h" 112 #include "auth-options.h" 113 #include "version.h" 114 #include "ssherr.h" 115 #include "sk-api.h" 116 #include "srclimit.h" 117 #include "dh.h" 118 119 #include "pfilter.h" 120 121 #ifdef LIBWRAP 122 #include <tcpd.h> 123 #include <syslog.h> 124 int allow_severity = LOG_INFO; 125 int deny_severity = LOG_WARNING; 126 #endif /* LIBWRAP */ 127 128 #ifdef WITH_LDAP_PUBKEY 129 #include "ldapauth.h" 130 #endif 131 132 #ifndef HOST_NAME_MAX 133 #define HOST_NAME_MAX MAXHOSTNAMELEN 134 #endif 135 136 /* Re-exec fds */ 137 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 138 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 139 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 140 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 141 142 extern char *__progname; 143 144 /* Server configuration options. */ 145 ServerOptions options; 146 147 /* Name of the server configuration file. */ 148 const char *config_file_name = _PATH_SERVER_CONFIG_FILE; 149 150 /* 151 * Debug mode flag. This can be set on the command line. If debug 152 * mode is enabled, extra debugging output will be sent to the system 153 * log, the daemon will not go to background, and will exit after processing 154 * the first connection. 155 */ 156 int debug_flag = 0; 157 158 /* 159 * Indicating that the daemon should only test the configuration and keys. 160 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 161 * configuration, optionally using connection information provided by the 162 * "-C" flag. 163 */ 164 static int test_flag = 0; 165 166 /* Flag indicating that the daemon is being started from inetd. */ 167 static int inetd_flag = 0; 168 169 /* Flag indicating that sshd should not detach and become a daemon. */ 170 static int no_daemon_flag = 0; 171 172 /* debug goes to stderr unless inetd_flag is set */ 173 static int log_stderr = 0; 174 175 /* Saved arguments to main(). */ 176 static char **saved_argv; 177 178 /* re-exec */ 179 static int rexeced_flag = 0; 180 static int rexec_flag = 1; 181 static int rexec_argc = 0; 182 static char **rexec_argv; 183 184 /* 185 * The sockets that the server is listening; this is used in the SIGHUP 186 * signal handler. 187 */ 188 #define MAX_LISTEN_SOCKS 16 189 static int listen_socks[MAX_LISTEN_SOCKS]; 190 static int num_listen_socks = 0; 191 192 /* Daemon's agent connection */ 193 int auth_sock = -1; 194 static int have_agent = 0; 195 196 /* 197 * Any really sensitive data in the application is contained in this 198 * structure. The idea is that this structure could be locked into memory so 199 * that the pages do not get written into swap. However, there are some 200 * problems. The private key contains BIGNUMs, and we do not (in principle) 201 * have access to the internals of them, and locking just the structure is 202 * not very useful. Currently, memory locking is not implemented. 203 */ 204 struct { 205 struct sshkey **host_keys; /* all private host keys */ 206 struct sshkey **host_pubkeys; /* all public host keys */ 207 struct sshkey **host_certificates; /* all public host certificates */ 208 int have_ssh2_key; 209 } sensitive_data; 210 211 /* This is set to true when a signal is received. */ 212 static volatile sig_atomic_t received_sighup = 0; 213 static volatile sig_atomic_t received_sigterm = 0; 214 215 /* record remote hostname or ip */ 216 u_int utmp_len = HOST_NAME_MAX+1; 217 218 /* 219 * startup_pipes/flags are used for tracking children of the listening sshd 220 * process early in their lifespans. This tracking is needed for three things: 221 * 222 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 223 * connections. 224 * 2) Avoiding a race condition for SIGHUP processing, where child processes 225 * may have listen_socks open that could collide with main listener process 226 * after it restarts. 227 * 3) Ensuring that rexec'd sshd processes have received their initial state 228 * from the parent listen process before handling SIGHUP. 229 * 230 * Child processes signal that they have completed closure of the listen_socks 231 * and (if applicable) received their rexec state by sending a char over their 232 * sock. Child processes signal that authentication has completed by closing 233 * the sock (or by exiting). 234 */ 235 static int *startup_pipes = NULL; 236 static int *startup_flags = NULL; /* Indicates child closed listener */ 237 static int startup_pipe = -1; /* in child */ 238 239 /* variables used for privilege separation */ 240 int use_privsep = -1; 241 struct monitor *pmonitor = NULL; 242 int privsep_is_preauth = 1; 243 244 /* global connection state and authentication contexts */ 245 Authctxt *the_authctxt = NULL; 246 struct ssh *the_active_state; 247 248 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 249 struct sshauthopt *auth_opts = NULL; 250 251 /* sshd_config buffer */ 252 struct sshbuf *cfg; 253 254 /* Included files from the configuration file */ 255 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 256 257 /* message to be displayed after login */ 258 struct sshbuf *loginmsg; 259 260 /* Prototypes for various functions defined later in this file. */ 261 void destroy_sensitive_data(void); 262 void demote_sensitive_data(void); 263 static void do_ssh2_kex(struct ssh *); 264 265 static char *listener_proctitle; 266 267 /* 268 * Close all listening sockets 269 */ 270 static void 271 close_listen_socks(void) 272 { 273 int i; 274 275 for (i = 0; i < num_listen_socks; i++) 276 close(listen_socks[i]); 277 num_listen_socks = 0; 278 } 279 280 static void 281 close_startup_pipes(void) 282 { 283 int i; 284 285 if (startup_pipes) 286 for (i = 0; i < options.max_startups; i++) 287 if (startup_pipes[i] != -1) 288 close(startup_pipes[i]); 289 } 290 291 /* 292 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 293 * the effect is to reread the configuration file (and to regenerate 294 * the server key). 295 */ 296 297 /*ARGSUSED*/ 298 static void 299 sighup_handler(int sig) 300 { 301 received_sighup = 1; 302 } 303 304 /* 305 * Called from the main program after receiving SIGHUP. 306 * Restarts the server. 307 */ 308 __dead static void 309 sighup_restart(void) 310 { 311 logit("Received SIGHUP; restarting."); 312 if (options.pid_file != NULL) 313 unlink(options.pid_file); 314 close_listen_socks(); 315 close_startup_pipes(); 316 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 317 execv(saved_argv[0], saved_argv); 318 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 319 strerror(errno)); 320 exit(1); 321 } 322 323 /* 324 * Generic signal handler for terminating signals in the master daemon. 325 */ 326 /*ARGSUSED*/ 327 static void 328 sigterm_handler(int sig) 329 { 330 received_sigterm = sig; 331 } 332 333 /* 334 * SIGCHLD handler. This is called whenever a child dies. This will then 335 * reap any zombies left by exited children. 336 */ 337 /*ARGSUSED*/ 338 static void 339 main_sigchld_handler(int sig) 340 { 341 int save_errno = errno; 342 pid_t pid; 343 int status; 344 345 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 346 (pid == -1 && errno == EINTR)) 347 ; 348 errno = save_errno; 349 } 350 351 /* 352 * Signal handler for the alarm after the login grace period has expired. 353 */ 354 /*ARGSUSED*/ 355 __dead static void 356 grace_alarm_handler(int sig) 357 { 358 pfilter_notify(1); 359 /* 360 * Try to kill any processes that we have spawned, E.g. authorized 361 * keys command helpers or privsep children. 362 */ 363 if (getpgid(0) == getpid()) { 364 ssh_signal(SIGTERM, SIG_IGN); 365 kill(0, SIGTERM); 366 } 367 368 /* Log error and exit. */ 369 sigdie("Timeout before authentication for %s port %d", 370 ssh_remote_ipaddr(the_active_state), 371 ssh_remote_port(the_active_state)); 372 } 373 374 /* Destroy the host and server keys. They will no longer be needed. */ 375 void 376 destroy_sensitive_data(void) 377 { 378 u_int i; 379 380 for (i = 0; i < options.num_host_key_files; i++) { 381 if (sensitive_data.host_keys[i]) { 382 sshkey_free(sensitive_data.host_keys[i]); 383 sensitive_data.host_keys[i] = NULL; 384 } 385 if (sensitive_data.host_certificates[i]) { 386 sshkey_free(sensitive_data.host_certificates[i]); 387 sensitive_data.host_certificates[i] = NULL; 388 } 389 } 390 } 391 392 /* Demote private to public keys for network child */ 393 void 394 demote_sensitive_data(void) 395 { 396 struct sshkey *tmp; 397 u_int i; 398 int r; 399 400 for (i = 0; i < options.num_host_key_files; i++) { 401 if (sensitive_data.host_keys[i]) { 402 if ((r = sshkey_from_private( 403 sensitive_data.host_keys[i], &tmp)) != 0) 404 fatal_r(r, "could not demote host %s key", 405 sshkey_type(sensitive_data.host_keys[i])); 406 sshkey_free(sensitive_data.host_keys[i]); 407 sensitive_data.host_keys[i] = tmp; 408 } 409 /* Certs do not need demotion */ 410 } 411 } 412 413 static void 414 privsep_preauth_child(void) 415 { 416 gid_t gidset[1]; 417 struct passwd *pw; 418 419 /* Enable challenge-response authentication for privilege separation */ 420 privsep_challenge_enable(); 421 422 #ifdef GSSAPI 423 /* Cache supported mechanism OIDs for later use */ 424 ssh_gssapi_prepare_supported_oids(); 425 #endif 426 427 /* Demote the private keys to public keys. */ 428 demote_sensitive_data(); 429 430 /* Demote the child */ 431 if (getuid() == 0 || geteuid() == 0) { 432 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) 433 fatal("Privilege separation user %s does not exist", 434 SSH_PRIVSEP_USER); 435 pw = pwcopy(pw); /* Ensure mutable */ 436 endpwent(); 437 freezero(pw->pw_passwd, strlen(pw->pw_passwd)); 438 439 /* Change our root directory */ 440 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 441 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 442 strerror(errno)); 443 if (chdir("/") == -1) 444 fatal("chdir(\"/\"): %s", strerror(errno)); 445 446 /* 447 * Drop our privileges 448 * NB. Can't use setusercontext() after chroot. 449 */ 450 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, 451 (u_int)pw->pw_gid); 452 gidset[0] = pw->pw_gid; 453 if (setgroups(1, gidset) == -1) 454 fatal("setgroups: %.100s", strerror(errno)); 455 permanently_set_uid(pw); 456 } 457 } 458 459 static int 460 privsep_preauth(struct ssh *ssh) 461 { 462 int status, r; 463 pid_t pid; 464 struct ssh_sandbox *box = NULL; 465 466 /* Set up unprivileged child process to deal with network data */ 467 pmonitor = monitor_init(); 468 /* Store a pointer to the kex for later rekeying */ 469 pmonitor->m_pkex = &ssh->kex; 470 471 if (use_privsep == PRIVSEP_ON) 472 box = ssh_sandbox_init(); 473 pid = fork(); 474 if (pid == -1) { 475 fatal("fork of unprivileged child failed"); 476 } else if (pid != 0) { 477 debug2("Network child is on pid %ld", (long)pid); 478 479 pmonitor->m_pid = pid; 480 if (have_agent) { 481 r = ssh_get_authentication_socket(&auth_sock); 482 if (r != 0) { 483 error_r(r, "Could not get agent socket"); 484 have_agent = 0; 485 } 486 } 487 if (box != NULL) 488 ssh_sandbox_parent_preauth(box, pid); 489 monitor_child_preauth(ssh, pmonitor); 490 491 /* Wait for the child's exit status */ 492 while (waitpid(pid, &status, 0) == -1) { 493 if (errno == EINTR) 494 continue; 495 pmonitor->m_pid = -1; 496 fatal_f("waitpid: %s", strerror(errno)); 497 } 498 privsep_is_preauth = 0; 499 pmonitor->m_pid = -1; 500 if (WIFEXITED(status)) { 501 if (WEXITSTATUS(status) != 0) 502 fatal_f("preauth child exited with status %d", 503 WEXITSTATUS(status)); 504 } else if (WIFSIGNALED(status)) 505 fatal_f("preauth child terminated by signal %d", 506 WTERMSIG(status)); 507 if (box != NULL) 508 ssh_sandbox_parent_finish(box); 509 return 1; 510 } else { 511 /* child */ 512 close(pmonitor->m_sendfd); 513 close(pmonitor->m_log_recvfd); 514 515 /* Arrange for logging to be sent to the monitor */ 516 set_log_handler(mm_log_handler, pmonitor); 517 518 privsep_preauth_child(); 519 setproctitle("%s", "[net]"); 520 if (box != NULL) 521 ssh_sandbox_child(box); 522 523 return 0; 524 } 525 } 526 527 static void 528 privsep_postauth(struct ssh *ssh, Authctxt *authctxt) 529 { 530 ssh->authctxt = authctxt; 531 if (authctxt->pw->pw_uid == 0) { 532 /* File descriptor passing is broken or root login */ 533 use_privsep = 0; 534 goto skip; 535 } 536 537 /* New socket pair */ 538 monitor_reinit(pmonitor); 539 540 pmonitor->m_pid = fork(); 541 if (pmonitor->m_pid == -1) 542 fatal("fork of unprivileged child failed"); 543 else if (pmonitor->m_pid != 0) { 544 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 545 sshbuf_reset(loginmsg); 546 monitor_clear_keystate(ssh, pmonitor); 547 monitor_child_postauth(ssh, pmonitor); 548 549 /* NEVERREACHED */ 550 exit(0); 551 } 552 553 /* child */ 554 555 close(pmonitor->m_sendfd); 556 pmonitor->m_sendfd = -1; 557 558 /* Demote the private keys to public keys. */ 559 demote_sensitive_data(); 560 561 /* Drop privileges */ 562 do_setusercontext(authctxt->pw); 563 564 skip: 565 /* It is safe now to apply the key state */ 566 monitor_apply_keystate(ssh, pmonitor); 567 568 /* 569 * Tell the packet layer that authentication was successful, since 570 * this information is not part of the key state. 571 */ 572 ssh_packet_set_authenticated(ssh); 573 } 574 575 static void 576 append_hostkey_type(struct sshbuf *b, const char *s) 577 { 578 int r; 579 580 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 581 debug3_f("%s key not permitted by HostkeyAlgorithms", s); 582 return; 583 } 584 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 585 fatal_fr(r, "sshbuf_putf"); 586 } 587 588 static char * 589 list_hostkey_types(void) 590 { 591 struct sshbuf *b; 592 struct sshkey *key; 593 char *ret; 594 u_int i; 595 596 if ((b = sshbuf_new()) == NULL) 597 fatal_f("sshbuf_new failed"); 598 for (i = 0; i < options.num_host_key_files; i++) { 599 key = sensitive_data.host_keys[i]; 600 if (key == NULL) 601 key = sensitive_data.host_pubkeys[i]; 602 if (key == NULL) 603 continue; 604 switch (key->type) { 605 case KEY_RSA: 606 /* for RSA we also support SHA2 signatures */ 607 append_hostkey_type(b, "rsa-sha2-512"); 608 append_hostkey_type(b, "rsa-sha2-256"); 609 /* FALLTHROUGH */ 610 case KEY_DSA: 611 case KEY_ECDSA: 612 case KEY_ED25519: 613 case KEY_ECDSA_SK: 614 case KEY_ED25519_SK: 615 case KEY_XMSS: 616 append_hostkey_type(b, sshkey_ssh_name(key)); 617 break; 618 } 619 /* If the private key has a cert peer, then list that too */ 620 key = sensitive_data.host_certificates[i]; 621 if (key == NULL) 622 continue; 623 switch (key->type) { 624 case KEY_RSA_CERT: 625 /* for RSA we also support SHA2 signatures */ 626 append_hostkey_type(b, 627 "rsa-sha2-512-cert-v01@openssh.com"); 628 append_hostkey_type(b, 629 "rsa-sha2-256-cert-v01@openssh.com"); 630 /* FALLTHROUGH */ 631 case KEY_DSA_CERT: 632 case KEY_ECDSA_CERT: 633 case KEY_ED25519_CERT: 634 case KEY_ECDSA_SK_CERT: 635 case KEY_ED25519_SK_CERT: 636 case KEY_XMSS_CERT: 637 append_hostkey_type(b, sshkey_ssh_name(key)); 638 break; 639 } 640 } 641 if ((ret = sshbuf_dup_string(b)) == NULL) 642 fatal_f("sshbuf_dup_string failed"); 643 sshbuf_free(b); 644 debug_f("%s", ret); 645 return ret; 646 } 647 648 static struct sshkey * 649 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 650 { 651 u_int i; 652 struct sshkey *key; 653 654 for (i = 0; i < options.num_host_key_files; i++) { 655 switch (type) { 656 case KEY_RSA_CERT: 657 case KEY_DSA_CERT: 658 case KEY_ECDSA_CERT: 659 case KEY_ED25519_CERT: 660 case KEY_ECDSA_SK_CERT: 661 case KEY_ED25519_SK_CERT: 662 case KEY_XMSS_CERT: 663 key = sensitive_data.host_certificates[i]; 664 break; 665 default: 666 key = sensitive_data.host_keys[i]; 667 if (key == NULL && !need_private) 668 key = sensitive_data.host_pubkeys[i]; 669 break; 670 } 671 if (key == NULL || key->type != type) 672 continue; 673 switch (type) { 674 case KEY_ECDSA: 675 case KEY_ECDSA_SK: 676 case KEY_ECDSA_CERT: 677 case KEY_ECDSA_SK_CERT: 678 if (key->ecdsa_nid != nid) 679 continue; 680 /* FALLTHROUGH */ 681 default: 682 return need_private ? 683 sensitive_data.host_keys[i] : key; 684 } 685 } 686 return NULL; 687 } 688 689 struct sshkey * 690 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 691 { 692 return get_hostkey_by_type(type, nid, 0, ssh); 693 } 694 695 struct sshkey * 696 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 697 { 698 return get_hostkey_by_type(type, nid, 1, ssh); 699 } 700 701 struct sshkey * 702 get_hostkey_by_index(int ind) 703 { 704 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 705 return (NULL); 706 return (sensitive_data.host_keys[ind]); 707 } 708 709 struct sshkey * 710 get_hostkey_public_by_index(int ind, struct ssh *ssh) 711 { 712 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 713 return (NULL); 714 return (sensitive_data.host_pubkeys[ind]); 715 } 716 717 int 718 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 719 { 720 u_int i; 721 722 for (i = 0; i < options.num_host_key_files; i++) { 723 if (sshkey_is_cert(key)) { 724 if (key == sensitive_data.host_certificates[i] || 725 (compare && sensitive_data.host_certificates[i] && 726 sshkey_equal(key, 727 sensitive_data.host_certificates[i]))) 728 return (i); 729 } else { 730 if (key == sensitive_data.host_keys[i] || 731 (compare && sensitive_data.host_keys[i] && 732 sshkey_equal(key, sensitive_data.host_keys[i]))) 733 return (i); 734 if (key == sensitive_data.host_pubkeys[i] || 735 (compare && sensitive_data.host_pubkeys[i] && 736 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 737 return (i); 738 } 739 } 740 return (-1); 741 } 742 743 /* Inform the client of all hostkeys */ 744 static void 745 notify_hostkeys(struct ssh *ssh) 746 { 747 struct sshbuf *buf; 748 struct sshkey *key; 749 u_int i, nkeys; 750 int r; 751 char *fp; 752 753 /* Some clients cannot cope with the hostkeys message, skip those. */ 754 if (ssh->compat & SSH_BUG_HOSTKEYS) 755 return; 756 757 if ((buf = sshbuf_new()) == NULL) 758 fatal_f("sshbuf_new"); 759 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 760 key = get_hostkey_public_by_index(i, ssh); 761 if (key == NULL || key->type == KEY_UNSPEC || 762 sshkey_is_cert(key)) 763 continue; 764 fp = sshkey_fingerprint(key, options.fingerprint_hash, 765 SSH_FP_DEFAULT); 766 debug3_f("key %d: %s %s", i, sshkey_ssh_name(key), fp); 767 free(fp); 768 if (nkeys == 0) { 769 /* 770 * Start building the request when we find the 771 * first usable key. 772 */ 773 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 774 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || 775 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ 776 sshpkt_fatal(ssh, r, "%s: start request", __func__); 777 } 778 /* Append the key to the request */ 779 sshbuf_reset(buf); 780 if ((r = sshkey_putb(key, buf)) != 0) 781 fatal_fr(r, "couldn't put hostkey %d", i); 782 if ((r = sshpkt_put_stringb(ssh, buf)) != 0) 783 sshpkt_fatal(ssh, r, "%s: append key", __func__); 784 nkeys++; 785 } 786 debug3_f("sent %u hostkeys", nkeys); 787 if (nkeys == 0) 788 fatal_f("no hostkeys"); 789 if ((r = sshpkt_send(ssh)) != 0) 790 sshpkt_fatal(ssh, r, "%s: send", __func__); 791 sshbuf_free(buf); 792 } 793 794 /* 795 * returns 1 if connection should be dropped, 0 otherwise. 796 * dropping starts at connection #max_startups_begin with a probability 797 * of (max_startups_rate/100). the probability increases linearly until 798 * all connections are dropped for startups > max_startups 799 */ 800 static int 801 should_drop_connection(int startups) 802 { 803 int p, r; 804 805 if (startups < options.max_startups_begin) 806 return 0; 807 if (startups >= options.max_startups) 808 return 1; 809 if (options.max_startups_rate == 100) 810 return 1; 811 812 p = 100 - options.max_startups_rate; 813 p *= startups - options.max_startups_begin; 814 p /= options.max_startups - options.max_startups_begin; 815 p += options.max_startups_rate; 816 r = arc4random_uniform(100); 817 818 debug_f("p %d, r %d", p, r); 819 return (r < p) ? 1 : 0; 820 } 821 822 /* 823 * Check whether connection should be accepted by MaxStartups. 824 * Returns 0 if the connection is accepted. If the connection is refused, 825 * returns 1 and attempts to send notification to client. 826 * Logs when the MaxStartups condition is entered or exited, and periodically 827 * while in that state. 828 */ 829 static int 830 drop_connection(int sock, int startups, int notify_pipe) 831 { 832 char *laddr, *raddr; 833 const char msg[] = "Exceeded MaxStartups\r\n"; 834 static time_t last_drop, first_drop; 835 static u_int ndropped; 836 LogLevel drop_level = SYSLOG_LEVEL_VERBOSE; 837 time_t now; 838 839 now = monotime(); 840 if (!should_drop_connection(startups) && 841 srclimit_check_allow(sock, notify_pipe) == 1) { 842 if (last_drop != 0 && 843 startups < options.max_startups_begin - 1) { 844 /* XXX maybe need better hysteresis here */ 845 logit("exited MaxStartups throttling after %s, " 846 "%u connections dropped", 847 fmt_timeframe(now - first_drop), ndropped); 848 last_drop = 0; 849 } 850 return 0; 851 } 852 853 #define SSHD_MAXSTARTUPS_LOG_INTERVAL (5 * 60) 854 if (last_drop == 0) { 855 error("beginning MaxStartups throttling"); 856 drop_level = SYSLOG_LEVEL_INFO; 857 first_drop = now; 858 ndropped = 0; 859 } else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) { 860 /* Periodic logs */ 861 error("in MaxStartups throttling for %s, " 862 "%u connections dropped", 863 fmt_timeframe(now - first_drop), ndropped + 1); 864 drop_level = SYSLOG_LEVEL_INFO; 865 } 866 last_drop = now; 867 ndropped++; 868 869 laddr = get_local_ipaddr(sock); 870 raddr = get_peer_ipaddr(sock); 871 do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d " 872 "past MaxStartups", startups, raddr, get_peer_port(sock), 873 laddr, get_local_port(sock)); 874 free(laddr); 875 free(raddr); 876 /* best-effort notification to client */ 877 (void)write(sock, msg, sizeof(msg) - 1); 878 return 1; 879 } 880 881 __dead static void 882 usage(void) 883 { 884 fprintf(stderr, "%s, %s\n", SSH_VERSION, SSH_OPENSSL_VERSION); 885 fprintf(stderr, 886 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 887 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 888 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 889 ); 890 exit(1); 891 } 892 893 static void 894 send_rexec_state(int fd, struct sshbuf *conf) 895 { 896 struct sshbuf *m = NULL, *inc = NULL; 897 struct include_item *item = NULL; 898 int r; 899 900 debug3_f("entering fd = %d config len %zu", fd, 901 sshbuf_len(conf)); 902 903 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 904 fatal_f("sshbuf_new failed"); 905 906 /* pack includes into a string */ 907 TAILQ_FOREACH(item, &includes, entry) { 908 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 909 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 910 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 911 fatal_fr(r, "compose includes"); 912 } 913 914 /* 915 * Protocol from reexec master to child: 916 * string configuration 917 * string included_files[] { 918 * string selector 919 * string filename 920 * string contents 921 * } 922 */ 923 if ((r = sshbuf_put_stringb(m, conf)) != 0 || 924 (r = sshbuf_put_stringb(m, inc)) != 0) 925 fatal_fr(r, "compose config"); 926 if (ssh_msg_send(fd, 0, m) == -1) 927 error_f("ssh_msg_send failed"); 928 929 sshbuf_free(m); 930 sshbuf_free(inc); 931 932 debug3_f("done"); 933 } 934 935 static void 936 recv_rexec_state(int fd, struct sshbuf *conf) 937 { 938 struct sshbuf *m, *inc; 939 u_char *cp, ver; 940 size_t len; 941 int r; 942 struct include_item *item; 943 944 debug3_f("entering fd = %d", fd); 945 946 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 947 fatal_f("sshbuf_new failed"); 948 if (ssh_msg_recv(fd, m) == -1) 949 fatal_f("ssh_msg_recv failed"); 950 if ((r = sshbuf_get_u8(m, &ver)) != 0) 951 fatal_fr(r, "parse version"); 952 if (ver != 0) 953 fatal_f("rexec version mismatch"); 954 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || 955 (r = sshbuf_get_stringb(m, inc)) != 0) 956 fatal_fr(r, "parse config"); 957 958 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 959 fatal_fr(r, "sshbuf_put"); 960 961 while (sshbuf_len(inc) != 0) { 962 item = xcalloc(1, sizeof(*item)); 963 if ((item->contents = sshbuf_new()) == NULL) 964 fatal_f("sshbuf_new failed"); 965 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 || 966 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 || 967 (r = sshbuf_get_stringb(inc, item->contents)) != 0) 968 fatal_fr(r, "parse includes"); 969 TAILQ_INSERT_TAIL(&includes, item, entry); 970 } 971 972 free(cp); 973 sshbuf_free(m); 974 975 debug3_f("done"); 976 } 977 978 /* Accept a connection from inetd */ 979 static void 980 server_accept_inetd(int *sock_in, int *sock_out) 981 { 982 if (rexeced_flag) { 983 close(REEXEC_CONFIG_PASS_FD); 984 *sock_in = *sock_out = dup(STDIN_FILENO); 985 } else { 986 *sock_in = dup(STDIN_FILENO); 987 *sock_out = dup(STDOUT_FILENO); 988 } 989 /* 990 * We intentionally do not close the descriptors 0, 1, and 2 991 * as our code for setting the descriptors won't work if 992 * ttyfd happens to be one of those. 993 */ 994 if (stdfd_devnull(1, 1, !log_stderr) == -1) 995 error_f("stdfd_devnull failed"); 996 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 997 } 998 999 /* 1000 * Listen for TCP connections 1001 */ 1002 static void 1003 listen_on_addrs(struct listenaddr *la) 1004 { 1005 int ret, listen_sock; 1006 struct addrinfo *ai; 1007 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1008 int socksize; 1009 socklen_t socksizelen = sizeof(int); 1010 1011 for (ai = la->addrs; ai; ai = ai->ai_next) { 1012 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1013 continue; 1014 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1015 fatal("Too many listen sockets. " 1016 "Enlarge MAX_LISTEN_SOCKS"); 1017 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1018 ntop, sizeof(ntop), strport, sizeof(strport), 1019 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1020 error("getnameinfo failed: %.100s", 1021 ssh_gai_strerror(ret)); 1022 continue; 1023 } 1024 /* Create socket for listening. */ 1025 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1026 ai->ai_protocol); 1027 if (listen_sock == -1) { 1028 /* kernel may not support ipv6 */ 1029 verbose("socket: %.100s", strerror(errno)); 1030 continue; 1031 } 1032 if (set_nonblock(listen_sock) == -1) { 1033 close(listen_sock); 1034 continue; 1035 } 1036 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1037 verbose("socket: CLOEXEC: %s", strerror(errno)); 1038 close(listen_sock); 1039 continue; 1040 } 1041 /* Socket options */ 1042 set_reuseaddr(listen_sock); 1043 if (la->rdomain != NULL && 1044 set_rdomain(listen_sock, la->rdomain) == -1) { 1045 close(listen_sock); 1046 continue; 1047 } 1048 1049 debug("Bind to port %s on %s.", strport, ntop); 1050 1051 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, 1052 &socksize, &socksizelen); 1053 debug("Server TCP RWIN socket size: %d", socksize); 1054 debug("HPN Buffer Size: %d", options.hpn_buffer_size); 1055 1056 /* Bind the socket to the desired port. */ 1057 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 1058 error("Bind to port %s on %s failed: %.200s.", 1059 strport, ntop, strerror(errno)); 1060 close(listen_sock); 1061 continue; 1062 } 1063 listen_socks[num_listen_socks] = listen_sock; 1064 num_listen_socks++; 1065 1066 /* Start listening on the port. */ 1067 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 1068 fatal("listen on [%s]:%s: %.100s", 1069 ntop, strport, strerror(errno)); 1070 logit("Server listening on %s port %s%s%s.", 1071 ntop, strport, 1072 la->rdomain == NULL ? "" : " rdomain ", 1073 la->rdomain == NULL ? "" : la->rdomain); 1074 } 1075 } 1076 1077 static void 1078 server_listen(void) 1079 { 1080 u_int i; 1081 1082 /* Initialise per-source limit tracking. */ 1083 srclimit_init(options.max_startups, options.per_source_max_startups, 1084 options.per_source_masklen_ipv4, options.per_source_masklen_ipv6); 1085 1086 for (i = 0; i < options.num_listen_addrs; i++) { 1087 listen_on_addrs(&options.listen_addrs[i]); 1088 freeaddrinfo(options.listen_addrs[i].addrs); 1089 free(options.listen_addrs[i].rdomain); 1090 memset(&options.listen_addrs[i], 0, 1091 sizeof(options.listen_addrs[i])); 1092 } 1093 free(options.listen_addrs); 1094 options.listen_addrs = NULL; 1095 options.num_listen_addrs = 0; 1096 1097 if (!num_listen_socks) 1098 fatal("Cannot bind any address."); 1099 } 1100 1101 /* 1102 * The main TCP accept loop. Note that, for the non-debug case, returns 1103 * from this function are in a forked subprocess. 1104 */ 1105 static void 1106 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1107 { 1108 struct pollfd *pfd = NULL; 1109 int i, j, ret, npfd; 1110 int ostartups = -1, startups = 0, listening = 0, lameduck = 0; 1111 int startup_p[2] = { -1 , -1 }, *startup_pollfd; 1112 char c = 0; 1113 struct sockaddr_storage from; 1114 socklen_t fromlen; 1115 pid_t pid; 1116 sigset_t nsigset, osigset; 1117 1118 /* setup fd set for accept */ 1119 /* pipes connected to unauthenticated child sshd processes */ 1120 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1121 startup_flags = xcalloc(options.max_startups, sizeof(int)); 1122 startup_pollfd = xcalloc(options.max_startups, sizeof(int)); 1123 for (i = 0; i < options.max_startups; i++) 1124 startup_pipes[i] = -1; 1125 1126 pfilter_init(); 1127 /* 1128 * Prepare signal mask that we use to block signals that might set 1129 * received_sigterm or received_sighup, so that we are guaranteed 1130 * to immediately wake up the ppoll if a signal is received after 1131 * the flag is checked. 1132 */ 1133 sigemptyset(&nsigset); 1134 sigaddset(&nsigset, SIGHUP); 1135 sigaddset(&nsigset, SIGCHLD); 1136 sigaddset(&nsigset, SIGTERM); 1137 sigaddset(&nsigset, SIGQUIT); 1138 1139 /* sized for worst-case */ 1140 pfd = xcalloc(num_listen_socks + options.max_startups, 1141 sizeof(struct pollfd)); 1142 1143 /* 1144 * Stay listening for connections until the system crashes or 1145 * the daemon is killed with a signal. 1146 */ 1147 for (;;) { 1148 sigprocmask(SIG_BLOCK, &nsigset, &osigset); 1149 if (received_sigterm) { 1150 logit("Received signal %d; terminating.", 1151 (int) received_sigterm); 1152 close_listen_socks(); 1153 if (options.pid_file != NULL) 1154 unlink(options.pid_file); 1155 exit(received_sigterm == SIGTERM ? 0 : 255); 1156 } 1157 if (ostartups != startups) { 1158 setproctitle("%s [listener] %d of %d-%d startups", 1159 listener_proctitle, startups, 1160 options.max_startups_begin, options.max_startups); 1161 ostartups = startups; 1162 } 1163 if (received_sighup) { 1164 if (!lameduck) { 1165 debug("Received SIGHUP; waiting for children"); 1166 close_listen_socks(); 1167 lameduck = 1; 1168 } 1169 if (listening <= 0) { 1170 sigprocmask(SIG_SETMASK, &osigset, NULL); 1171 sighup_restart(); 1172 } 1173 } 1174 1175 for (i = 0; i < num_listen_socks; i++) { 1176 pfd[i].fd = listen_socks[i]; 1177 pfd[i].events = POLLIN; 1178 } 1179 npfd = num_listen_socks; 1180 for (i = 0; i < options.max_startups; i++) { 1181 startup_pollfd[i] = -1; 1182 if (startup_pipes[i] != -1) { 1183 pfd[npfd].fd = startup_pipes[i]; 1184 pfd[npfd].events = POLLIN; 1185 startup_pollfd[i] = npfd++; 1186 } 1187 } 1188 1189 /* Wait until a connection arrives or a child exits. */ 1190 ret = ppoll(pfd, npfd, NULL, &osigset); 1191 if (ret == -1 && errno != EINTR) { 1192 error("ppoll: %.100s", strerror(errno)); 1193 if (errno == EINVAL) 1194 cleanup_exit(1); /* can't recover */ 1195 } 1196 sigprocmask(SIG_SETMASK, &osigset, NULL); 1197 if (ret == -1) 1198 continue; 1199 1200 for (i = 0; i < options.max_startups; i++) { 1201 if (startup_pipes[i] == -1 || 1202 startup_pollfd[i] == -1 || 1203 !(pfd[startup_pollfd[i]].revents & (POLLIN|POLLHUP))) 1204 continue; 1205 switch (read(startup_pipes[i], &c, sizeof(c))) { 1206 case -1: 1207 if (errno == EINTR || errno == EAGAIN) 1208 continue; 1209 if (errno != EPIPE) { 1210 error_f("startup pipe %d (fd=%d): " 1211 "read %s", i, startup_pipes[i], 1212 strerror(errno)); 1213 } 1214 /* FALLTHROUGH */ 1215 case 0: 1216 /* child exited or completed auth */ 1217 close(startup_pipes[i]); 1218 srclimit_done(startup_pipes[i]); 1219 startup_pipes[i] = -1; 1220 startups--; 1221 if (startup_flags[i]) 1222 listening--; 1223 break; 1224 case 1: 1225 /* child has finished preliminaries */ 1226 if (startup_flags[i]) { 1227 listening--; 1228 startup_flags[i] = 0; 1229 } 1230 break; 1231 } 1232 } 1233 for (i = 0; i < num_listen_socks; i++) { 1234 if (!(pfd[i].revents & POLLIN)) 1235 continue; 1236 fromlen = sizeof(from); 1237 *newsock = accept(listen_socks[i], 1238 (struct sockaddr *)&from, &fromlen); 1239 if (*newsock == -1) { 1240 if (errno != EINTR && errno != EWOULDBLOCK && 1241 errno != ECONNABORTED) 1242 error("accept: %.100s", 1243 strerror(errno)); 1244 if (errno == EMFILE || errno == ENFILE) 1245 usleep(100 * 1000); 1246 continue; 1247 } 1248 if (unset_nonblock(*newsock) == -1) { 1249 close(*newsock); 1250 continue; 1251 } 1252 if (pipe(startup_p) == -1) { 1253 error_f("pipe(startup_p): %s", strerror(errno)); 1254 close(*newsock); 1255 continue; 1256 } 1257 if (drop_connection(*newsock, startups, startup_p[0])) { 1258 close(*newsock); 1259 close(startup_p[0]); 1260 close(startup_p[1]); 1261 continue; 1262 } 1263 1264 if (rexec_flag && socketpair(AF_UNIX, 1265 SOCK_STREAM, 0, config_s) == -1) { 1266 error("reexec socketpair: %s", 1267 strerror(errno)); 1268 close(*newsock); 1269 close(startup_p[0]); 1270 close(startup_p[1]); 1271 continue; 1272 } 1273 1274 for (j = 0; j < options.max_startups; j++) 1275 if (startup_pipes[j] == -1) { 1276 startup_pipes[j] = startup_p[0]; 1277 startups++; 1278 startup_flags[j] = 1; 1279 break; 1280 } 1281 1282 /* 1283 * Got connection. Fork a child to handle it, unless 1284 * we are in debugging mode. 1285 */ 1286 if (debug_flag) { 1287 /* 1288 * In debugging mode. Close the listening 1289 * socket, and start processing the 1290 * connection without forking. 1291 */ 1292 debug("Server will not fork when running in debugging mode."); 1293 close_listen_socks(); 1294 *sock_in = *newsock; 1295 *sock_out = *newsock; 1296 close(startup_p[0]); 1297 close(startup_p[1]); 1298 startup_pipe = -1; 1299 pid = getpid(); 1300 if (rexec_flag) { 1301 send_rexec_state(config_s[0], cfg); 1302 close(config_s[0]); 1303 } 1304 free(pfd); 1305 return; 1306 } 1307 1308 /* 1309 * Normal production daemon. Fork, and have 1310 * the child process the connection. The 1311 * parent continues listening. 1312 */ 1313 listening++; 1314 if ((pid = fork()) == 0) { 1315 /* 1316 * Child. Close the listening and 1317 * max_startup sockets. Start using 1318 * the accepted socket. Reinitialize 1319 * logging (since our pid has changed). 1320 * We return from this function to handle 1321 * the connection. 1322 */ 1323 startup_pipe = startup_p[1]; 1324 close_startup_pipes(); 1325 close_listen_socks(); 1326 *sock_in = *newsock; 1327 *sock_out = *newsock; 1328 log_init(__progname, 1329 options.log_level, 1330 options.log_facility, 1331 log_stderr); 1332 if (rexec_flag) 1333 close(config_s[0]); 1334 else { 1335 /* 1336 * Signal parent that the preliminaries 1337 * for this child are complete. For the 1338 * re-exec case, this happens after the 1339 * child has received the rexec state 1340 * from the server. 1341 */ 1342 (void)atomicio(vwrite, startup_pipe, 1343 __UNCONST("\0"), 1); 1344 } 1345 free(pfd); 1346 return; 1347 } 1348 1349 /* Parent. Stay in the loop. */ 1350 if (pid == -1) 1351 error("fork: %.100s", strerror(errno)); 1352 else 1353 debug("Forked child %ld.", (long)pid); 1354 1355 close(startup_p[1]); 1356 1357 if (rexec_flag) { 1358 close(config_s[1]); 1359 send_rexec_state(config_s[0], cfg); 1360 close(config_s[0]); 1361 } 1362 close(*newsock); 1363 } 1364 } 1365 } 1366 1367 /* 1368 * If IP options are supported, make sure there are none (log and 1369 * return an error if any are found). Basically we are worried about 1370 * source routing; it can be used to pretend you are somebody 1371 * (ip-address) you are not. That itself may be "almost acceptable" 1372 * under certain circumstances, but rhosts authentication is useless 1373 * if source routing is accepted. Notice also that if we just dropped 1374 * source routing here, the other side could use IP spoofing to do 1375 * rest of the interaction and could still bypass security. So we 1376 * exit here if we detect any IP options. 1377 */ 1378 static void 1379 check_ip_options(struct ssh *ssh) 1380 { 1381 int sock_in = ssh_packet_get_connection_in(ssh); 1382 struct sockaddr_storage from; 1383 socklen_t fromlen = sizeof(from); 1384 #ifdef IP_OPTIONS 1385 socklen_t option_size, i; 1386 u_char opts[200]; 1387 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1388 char text[sizeof(opts) * 3 + 1]; 1389 #endif 1390 1391 memset(&from, 0, sizeof(from)); 1392 if (getpeername(sock_in, (struct sockaddr *)&from, 1393 &fromlen) == -1) 1394 return; 1395 if (from.ss_family != AF_INET) 1396 return; 1397 /* XXX IPv6 options? */ 1398 #ifdef IP_OPTIONS 1399 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1400 &option_size) >= 0 && option_size != 0) { 1401 text[0] = '\0'; 1402 for (i = 0; i < option_size; i++) 1403 snprintf(text + i*3, sizeof(text) - i*3, 1404 " %2.2x", opts[i]); 1405 fatal("Connection from %.100s port %d with IP opts: %.800s", 1406 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1407 } 1408 #endif 1409 return; 1410 } 1411 1412 /* Set the routing domain for this process */ 1413 #if !defined(__OpenBSD__) 1414 __dead 1415 #endif 1416 static void 1417 set_process_rdomain(struct ssh *ssh, const char *name) 1418 { 1419 #if defined(__OpenBSD__) 1420 int rtable, ortable = getrtable(); 1421 const char *errstr; 1422 1423 if (name == NULL) 1424 return; /* default */ 1425 1426 if (strcmp(name, "%D") == 0) { 1427 /* "expands" to routing domain of connection */ 1428 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1429 return; 1430 } 1431 1432 rtable = (int)strtonum(name, 0, 255, &errstr); 1433 if (errstr != NULL) /* Shouldn't happen */ 1434 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1435 if (rtable != ortable && setrtable(rtable) != 0) 1436 fatal("Unable to set routing domain %d: %s", 1437 rtable, strerror(errno)); 1438 debug_f("set routing domain %d (was %d)", rtable, ortable); 1439 #else /* defined(__OpenBSD__) */ 1440 fatal("Unable to set routing domain: not supported in this platform"); 1441 #endif 1442 } 1443 1444 static void 1445 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1446 struct sshkey *key) 1447 { 1448 static struct ssh_digest_ctx *ctx; 1449 u_char *hash; 1450 size_t len; 1451 struct sshbuf *buf; 1452 int r; 1453 1454 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1455 fatal_f("ssh_digest_start"); 1456 if (key == NULL) { /* finalize */ 1457 /* add server config in case we are using agent for host keys */ 1458 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1459 sshbuf_len(server_cfg)) != 0) 1460 fatal_f("ssh_digest_update"); 1461 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1462 hash = xmalloc(len); 1463 if (ssh_digest_final(ctx, hash, len) != 0) 1464 fatal_f("ssh_digest_final"); 1465 options.timing_secret = PEEK_U64(hash); 1466 freezero(hash, len); 1467 ssh_digest_free(ctx); 1468 ctx = NULL; 1469 return; 1470 } 1471 if ((buf = sshbuf_new()) == NULL) 1472 fatal_f("could not allocate buffer"); 1473 if ((r = sshkey_private_serialize(key, buf)) != 0) 1474 fatal_fr(r, "decode key"); 1475 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1476 fatal_f("ssh_digest_update"); 1477 sshbuf_reset(buf); 1478 sshbuf_free(buf); 1479 } 1480 1481 static char * 1482 prepare_proctitle(int ac, char **av) 1483 { 1484 char *ret = NULL; 1485 int i; 1486 1487 for (i = 0; i < ac; i++) 1488 xextendf(&ret, " ", "%s", av[i]); 1489 return ret; 1490 } 1491 1492 /* 1493 * Main program for the daemon. 1494 */ 1495 int 1496 main(int ac, char **av) 1497 { 1498 struct ssh *ssh = NULL; 1499 extern char *optarg; 1500 extern int optind; 1501 int r, opt, on = 1, already_daemon, remote_port; 1502 int sock_in = -1, sock_out = -1, newsock = -1; 1503 const char *remote_ip, *rdomain; 1504 char *fp, *line, *laddr, *logfile = NULL; 1505 int config_s[2] = { -1 , -1 }; 1506 u_int i, j; 1507 u_int64_t ibytes, obytes; 1508 mode_t new_umask; 1509 struct sshkey *key; 1510 struct sshkey *pubkey; 1511 int keytype; 1512 Authctxt *authctxt; 1513 struct connection_info *connection_info = NULL; 1514 1515 /* Save argv. */ 1516 saved_argv = av; 1517 rexec_argc = ac; 1518 1519 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1520 sanitise_stdfd(); 1521 1522 /* Initialize configuration options to their default values. */ 1523 initialize_server_options(&options); 1524 1525 /* Parse command-line arguments. */ 1526 while ((opt = getopt(ac, av, 1527 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1528 switch (opt) { 1529 case '4': 1530 options.address_family = AF_INET; 1531 break; 1532 case '6': 1533 options.address_family = AF_INET6; 1534 break; 1535 case 'f': 1536 config_file_name = optarg; 1537 break; 1538 case 'c': 1539 servconf_add_hostcert("[command-line]", 0, 1540 &options, optarg); 1541 break; 1542 case 'd': 1543 if (debug_flag == 0) { 1544 debug_flag = 1; 1545 options.log_level = SYSLOG_LEVEL_DEBUG1; 1546 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1547 options.log_level++; 1548 break; 1549 case 'D': 1550 no_daemon_flag = 1; 1551 break; 1552 case 'E': 1553 logfile = optarg; 1554 /* FALLTHROUGH */ 1555 case 'e': 1556 log_stderr = 1; 1557 break; 1558 case 'i': 1559 inetd_flag = 1; 1560 break; 1561 case 'r': 1562 rexec_flag = 0; 1563 break; 1564 case 'R': 1565 rexeced_flag = 1; 1566 inetd_flag = 1; 1567 break; 1568 case 'Q': 1569 /* ignored */ 1570 break; 1571 case 'q': 1572 options.log_level = SYSLOG_LEVEL_QUIET; 1573 break; 1574 case 'b': 1575 /* protocol 1, ignored */ 1576 break; 1577 case 'p': 1578 options.ports_from_cmdline = 1; 1579 if (options.num_ports >= MAX_PORTS) { 1580 fprintf(stderr, "too many ports.\n"); 1581 exit(1); 1582 } 1583 options.ports[options.num_ports++] = a2port(optarg); 1584 if (options.ports[options.num_ports-1] <= 0) { 1585 fprintf(stderr, "Bad port number.\n"); 1586 exit(1); 1587 } 1588 break; 1589 case 'g': 1590 if ((options.login_grace_time = convtime(optarg)) == -1) { 1591 fprintf(stderr, "Invalid login grace time.\n"); 1592 exit(1); 1593 } 1594 break; 1595 case 'k': 1596 /* protocol 1, ignored */ 1597 break; 1598 case 'h': 1599 servconf_add_hostkey("[command-line]", 0, 1600 &options, optarg, 1); 1601 break; 1602 case 't': 1603 test_flag = 1; 1604 break; 1605 case 'T': 1606 test_flag = 2; 1607 break; 1608 case 'C': 1609 connection_info = get_connection_info(ssh, 0, 0); 1610 if (parse_server_match_testspec(connection_info, 1611 optarg) == -1) 1612 exit(1); 1613 break; 1614 case 'u': 1615 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1616 if (utmp_len > HOST_NAME_MAX+1) { 1617 fprintf(stderr, "Invalid utmp length.\n"); 1618 exit(1); 1619 } 1620 break; 1621 case 'o': 1622 line = xstrdup(optarg); 1623 if (process_server_config_line(&options, line, 1624 "command-line", 0, NULL, NULL, &includes) != 0) 1625 exit(1); 1626 free(line); 1627 break; 1628 case '?': 1629 default: 1630 usage(); 1631 break; 1632 } 1633 } 1634 if (rexeced_flag || inetd_flag) 1635 rexec_flag = 0; 1636 if (!test_flag && rexec_flag && !path_absolute(av[0])) 1637 fatal("sshd re-exec requires execution with an absolute path"); 1638 if (rexeced_flag) 1639 r = closefrom(REEXEC_MIN_FREE_FD); 1640 else 1641 r = closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1642 if (r == -1) 1643 fatal("closefrom failed: %.200s", strerror(errno)); 1644 1645 #ifdef WITH_OPENSSL 1646 OpenSSL_add_all_algorithms(); 1647 #endif 1648 1649 /* If requested, redirect the logs to the specified logfile. */ 1650 if (logfile != NULL) 1651 log_redirect_stderr_to(logfile); 1652 /* 1653 * Force logging to stderr until we have loaded the private host 1654 * key (unless started from inetd) 1655 */ 1656 log_init(__progname, 1657 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1658 SYSLOG_LEVEL_INFO : options.log_level, 1659 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1660 SYSLOG_FACILITY_AUTH : options.log_facility, 1661 log_stderr || !inetd_flag || debug_flag); 1662 1663 sensitive_data.have_ssh2_key = 0; 1664 1665 /* 1666 * If we're not doing an extended test do not silently ignore connection 1667 * test params. 1668 */ 1669 if (test_flag < 2 && connection_info != NULL) 1670 fatal("Config test connection parameter (-C) provided without " 1671 "test mode (-T)"); 1672 1673 /* Fetch our configuration */ 1674 if ((cfg = sshbuf_new()) == NULL) 1675 fatal_f("sshbuf_new failed"); 1676 if (rexeced_flag) { 1677 setproctitle("%s", "[rexeced]"); 1678 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1679 if (!debug_flag) { 1680 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1681 close(REEXEC_STARTUP_PIPE_FD); 1682 /* 1683 * Signal parent that this child is at a point where 1684 * they can go away if they have a SIGHUP pending. 1685 */ 1686 (void)atomicio(vwrite, startup_pipe, __UNCONST("\0"), 1); 1687 } 1688 } else if (strcasecmp(config_file_name, "none") != 0) 1689 load_server_config(config_file_name, cfg); 1690 1691 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1692 cfg, &includes, NULL, rexeced_flag); 1693 1694 #ifdef WITH_OPENSSL 1695 if (options.moduli_file != NULL) 1696 dh_set_moduli_file(options.moduli_file); 1697 #endif 1698 1699 /* Fill in default values for those options not explicitly set. */ 1700 fill_default_server_options(&options); 1701 1702 /* Check that options are sensible */ 1703 if (options.authorized_keys_command_user == NULL && 1704 (options.authorized_keys_command != NULL && 1705 strcasecmp(options.authorized_keys_command, "none") != 0)) 1706 fatal("AuthorizedKeysCommand set without " 1707 "AuthorizedKeysCommandUser"); 1708 if (options.authorized_principals_command_user == NULL && 1709 (options.authorized_principals_command != NULL && 1710 strcasecmp(options.authorized_principals_command, "none") != 0)) 1711 fatal("AuthorizedPrincipalsCommand set without " 1712 "AuthorizedPrincipalsCommandUser"); 1713 1714 /* 1715 * Check whether there is any path through configured auth methods. 1716 * Unfortunately it is not possible to verify this generally before 1717 * daemonisation in the presence of Match block, but this catches 1718 * and warns for trivial misconfigurations that could break login. 1719 */ 1720 if (options.num_auth_methods != 0) { 1721 for (i = 0; i < options.num_auth_methods; i++) { 1722 if (auth2_methods_valid(options.auth_methods[i], 1723 1) == 0) 1724 break; 1725 } 1726 if (i >= options.num_auth_methods) 1727 fatal("AuthenticationMethods cannot be satisfied by " 1728 "enabled authentication methods"); 1729 } 1730 1731 /* Check that there are no remaining arguments. */ 1732 if (optind < ac) { 1733 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1734 exit(1); 1735 } 1736 1737 #ifdef WITH_LDAP_PUBKEY 1738 /* ldap_options_print(&options.lpk); */ 1739 /* XXX initialize/check ldap connection and set *LD */ 1740 if (options.lpk.on) { 1741 if (options.lpk.l_conf && (ldap_parse_lconf(&options.lpk) < 0) ) 1742 error("[LDAP] could not parse %s", options.lpk.l_conf); 1743 if (ldap_xconnect(&options.lpk) < 0) 1744 error("[LDAP] could not initialize ldap connection"); 1745 } 1746 #endif 1747 debug("sshd version %s, %s", SSH_VERSION, 1748 #ifdef WITH_OPENSSL 1749 OpenSSL_version(OPENSSL_VERSION) 1750 #else 1751 "without OpenSSL" 1752 #endif 1753 ); 1754 1755 /* load host keys */ 1756 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1757 sizeof(struct sshkey *)); 1758 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1759 sizeof(struct sshkey *)); 1760 1761 if (options.host_key_agent) { 1762 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1763 setenv(SSH_AUTHSOCKET_ENV_NAME, 1764 options.host_key_agent, 1); 1765 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1766 have_agent = 1; 1767 else 1768 error_r(r, "Could not connect to agent \"%s\"", 1769 options.host_key_agent); 1770 } 1771 1772 for (i = 0; i < options.num_host_key_files; i++) { 1773 int ll = options.host_key_file_userprovided[i] ? 1774 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1775 1776 if (options.host_key_files[i] == NULL) 1777 continue; 1778 if ((r = sshkey_load_private(options.host_key_files[i], "", 1779 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1780 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1781 options.host_key_files[i]); 1782 if (sshkey_is_sk(key) && 1783 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1784 debug("host key %s requires user presence, ignoring", 1785 options.host_key_files[i]); 1786 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1787 } 1788 if (r == 0 && key != NULL && 1789 (r = sshkey_shield_private(key)) != 0) { 1790 do_log2_r(r, ll, "Unable to shield host key \"%s\"", 1791 options.host_key_files[i]); 1792 sshkey_free(key); 1793 key = NULL; 1794 } 1795 if ((r = sshkey_load_public(options.host_key_files[i], 1796 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1797 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1798 options.host_key_files[i]); 1799 if (pubkey != NULL && key != NULL) { 1800 if (!sshkey_equal(pubkey, key)) { 1801 error("Public key for %s does not match " 1802 "private key", options.host_key_files[i]); 1803 sshkey_free(pubkey); 1804 pubkey = NULL; 1805 } 1806 } 1807 if (pubkey == NULL && key != NULL) { 1808 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1809 fatal_r(r, "Could not demote key: \"%s\"", 1810 options.host_key_files[i]); 1811 } 1812 if (pubkey != NULL && (r = sshkey_check_rsa_length(pubkey, 1813 options.required_rsa_size)) != 0) { 1814 error_fr(r, "Host key %s", options.host_key_files[i]); 1815 sshkey_free(pubkey); 1816 sshkey_free(key); 1817 continue; 1818 } 1819 sensitive_data.host_keys[i] = key; 1820 sensitive_data.host_pubkeys[i] = pubkey; 1821 1822 if (key == NULL && pubkey != NULL && have_agent) { 1823 debug("will rely on agent for hostkey %s", 1824 options.host_key_files[i]); 1825 keytype = pubkey->type; 1826 } else if (key != NULL) { 1827 keytype = key->type; 1828 accumulate_host_timing_secret(cfg, key); 1829 } else { 1830 do_log2(ll, "Unable to load host key: %s", 1831 options.host_key_files[i]); 1832 sensitive_data.host_keys[i] = NULL; 1833 sensitive_data.host_pubkeys[i] = NULL; 1834 continue; 1835 } 1836 1837 switch (keytype) { 1838 case KEY_RSA: 1839 case KEY_DSA: 1840 case KEY_ECDSA: 1841 case KEY_ED25519: 1842 case KEY_ECDSA_SK: 1843 case KEY_ED25519_SK: 1844 case KEY_XMSS: 1845 if (have_agent || key != NULL) 1846 sensitive_data.have_ssh2_key = 1; 1847 break; 1848 } 1849 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1850 SSH_FP_DEFAULT)) == NULL) 1851 fatal("sshkey_fingerprint failed"); 1852 debug("%s host key #%d: %s %s", 1853 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1854 free(fp); 1855 } 1856 accumulate_host_timing_secret(cfg, NULL); 1857 if (!sensitive_data.have_ssh2_key) { 1858 logit("sshd: no hostkeys available -- exiting."); 1859 exit(1); 1860 } 1861 1862 /* 1863 * Load certificates. They are stored in an array at identical 1864 * indices to the public keys that they relate to. 1865 */ 1866 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1867 sizeof(struct sshkey *)); 1868 for (i = 0; i < options.num_host_key_files; i++) 1869 sensitive_data.host_certificates[i] = NULL; 1870 1871 for (i = 0; i < options.num_host_cert_files; i++) { 1872 if (options.host_cert_files[i] == NULL) 1873 continue; 1874 if ((r = sshkey_load_public(options.host_cert_files[i], 1875 &key, NULL)) != 0) { 1876 error_r(r, "Could not load host certificate \"%s\"", 1877 options.host_cert_files[i]); 1878 continue; 1879 } 1880 if (!sshkey_is_cert(key)) { 1881 error("Certificate file is not a certificate: %s", 1882 options.host_cert_files[i]); 1883 sshkey_free(key); 1884 continue; 1885 } 1886 /* Find matching private key */ 1887 for (j = 0; j < options.num_host_key_files; j++) { 1888 if (sshkey_equal_public(key, 1889 sensitive_data.host_pubkeys[j])) { 1890 sensitive_data.host_certificates[j] = key; 1891 break; 1892 } 1893 } 1894 if (j >= options.num_host_key_files) { 1895 error("No matching private key for certificate: %s", 1896 options.host_cert_files[i]); 1897 sshkey_free(key); 1898 continue; 1899 } 1900 sensitive_data.host_certificates[j] = key; 1901 debug("host certificate: #%u type %d %s", j, key->type, 1902 sshkey_type(key)); 1903 } 1904 1905 if (use_privsep) { 1906 struct stat st; 1907 1908 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1909 fatal("Privilege separation user %s does not exist", 1910 SSH_PRIVSEP_USER); 1911 endpwent(); 1912 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1913 (S_ISDIR(st.st_mode) == 0)) 1914 fatal("Missing privilege separation directory: %s", 1915 _PATH_PRIVSEP_CHROOT_DIR); 1916 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1917 fatal("%s must be owned by root and not group or " 1918 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1919 } 1920 1921 if (test_flag > 1) { 1922 /* 1923 * If no connection info was provided by -C then use 1924 * use a blank one that will cause no predicate to match. 1925 */ 1926 if (connection_info == NULL) 1927 connection_info = get_connection_info(ssh, 0, 0); 1928 connection_info->test = 1; 1929 parse_server_match_config(&options, &includes, connection_info); 1930 dump_config(&options); 1931 } 1932 1933 /* Configuration looks good, so exit if in test mode. */ 1934 if (test_flag) 1935 exit(0); 1936 1937 if (rexec_flag) { 1938 if (rexec_argc < 0) 1939 fatal("rexec_argc %d < 0", rexec_argc); 1940 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1941 for (i = 0; i < (u_int)rexec_argc; i++) { 1942 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1943 rexec_argv[i] = saved_argv[i]; 1944 } 1945 rexec_argv[rexec_argc] = __UNCONST("-R"); 1946 rexec_argv[rexec_argc + 1] = NULL; 1947 } 1948 listener_proctitle = prepare_proctitle(ac, av); 1949 1950 /* Ensure that umask disallows at least group and world write */ 1951 new_umask = umask(0077) | 0022; 1952 (void) umask(new_umask); 1953 1954 /* Initialize the log (it is reinitialized below in case we forked). */ 1955 if (debug_flag && (!inetd_flag || rexeced_flag)) 1956 log_stderr = 1; 1957 log_init(__progname, options.log_level, 1958 options.log_facility, log_stderr); 1959 for (i = 0; i < options.num_log_verbose; i++) 1960 log_verbose_add(options.log_verbose[i]); 1961 1962 /* 1963 * If not in debugging mode, not started from inetd and not already 1964 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1965 * terminal, and fork. The original process exits. 1966 */ 1967 already_daemon = daemonized(); 1968 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1969 1970 if (daemon(0, 0) == -1) 1971 fatal("daemon() failed: %.200s", strerror(errno)); 1972 1973 disconnect_controlling_tty(); 1974 } 1975 /* Reinitialize the log (because of the fork above). */ 1976 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1977 1978 /* 1979 * Chdir to the root directory so that the current disk can be 1980 * unmounted if desired. 1981 */ 1982 if (chdir("/") == -1) 1983 error("chdir(\"/\"): %s", strerror(errno)); 1984 1985 /* ignore SIGPIPE */ 1986 ssh_signal(SIGPIPE, SIG_IGN); 1987 1988 /* Get a connection, either from inetd or a listening TCP socket */ 1989 if (inetd_flag) { 1990 server_accept_inetd(&sock_in, &sock_out); 1991 } else { 1992 server_listen(); 1993 1994 ssh_signal(SIGHUP, sighup_handler); 1995 ssh_signal(SIGCHLD, main_sigchld_handler); 1996 ssh_signal(SIGTERM, sigterm_handler); 1997 ssh_signal(SIGQUIT, sigterm_handler); 1998 1999 /* 2000 * Write out the pid file after the sigterm handler 2001 * is setup and the listen sockets are bound 2002 */ 2003 if (options.pid_file != NULL && !debug_flag) { 2004 FILE *f = fopen(options.pid_file, "w"); 2005 2006 if (f == NULL) { 2007 error("Couldn't create pid file \"%s\": %s", 2008 options.pid_file, strerror(errno)); 2009 } else { 2010 fprintf(f, "%ld\n", (long) getpid()); 2011 fclose(f); 2012 } 2013 } 2014 2015 /* Accept a connection and return in a forked child */ 2016 server_accept_loop(&sock_in, &sock_out, 2017 &newsock, config_s); 2018 } 2019 2020 /* This is the child processing a new connection. */ 2021 setproctitle("%s", "[accepted]"); 2022 2023 /* 2024 * Create a new session and process group since the 4.4BSD 2025 * setlogin() affects the entire process group. We don't 2026 * want the child to be able to affect the parent. 2027 */ 2028 if (!debug_flag && !inetd_flag && setsid() == -1) 2029 error("setsid: %.100s", strerror(errno)); 2030 2031 if (rexec_flag) { 2032 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 2033 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2034 dup2(newsock, STDIN_FILENO); 2035 dup2(STDIN_FILENO, STDOUT_FILENO); 2036 if (startup_pipe == -1) 2037 close(REEXEC_STARTUP_PIPE_FD); 2038 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 2039 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 2040 close(startup_pipe); 2041 startup_pipe = REEXEC_STARTUP_PIPE_FD; 2042 } 2043 2044 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 2045 close(config_s[1]); 2046 2047 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 2048 execv(rexec_argv[0], rexec_argv); 2049 2050 /* Reexec has failed, fall back and continue */ 2051 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 2052 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 2053 log_init(__progname, options.log_level, 2054 options.log_facility, log_stderr); 2055 2056 /* Clean up fds */ 2057 close(REEXEC_CONFIG_PASS_FD); 2058 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2059 if (stdfd_devnull(1, 1, 0) == -1) 2060 error_f("stdfd_devnull failed"); 2061 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2062 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2063 } 2064 2065 /* Executed child processes don't need these. */ 2066 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2067 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2068 2069 /* We will not restart on SIGHUP since it no longer makes sense. */ 2070 ssh_signal(SIGALRM, SIG_DFL); 2071 ssh_signal(SIGHUP, SIG_DFL); 2072 ssh_signal(SIGTERM, SIG_DFL); 2073 ssh_signal(SIGQUIT, SIG_DFL); 2074 ssh_signal(SIGCHLD, SIG_DFL); 2075 2076 /* 2077 * Register our connection. This turns encryption off because we do 2078 * not have a key. 2079 */ 2080 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 2081 fatal("Unable to create connection"); 2082 the_active_state = ssh; 2083 ssh_packet_set_server(ssh); 2084 2085 check_ip_options(ssh); 2086 2087 /* Prepare the channels layer */ 2088 channel_init_channels(ssh); 2089 channel_set_af(ssh, options.address_family); 2090 process_permitopen(ssh, &options); 2091 2092 /* Set SO_KEEPALIVE if requested. */ 2093 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 2094 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) 2095 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2096 2097 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2098 debug("ssh_remote_port failed"); 2099 cleanup_exit(255); 2100 } 2101 2102 /* 2103 * The rest of the code depends on the fact that 2104 * ssh_remote_ipaddr() caches the remote ip, even if 2105 * the socket goes away. 2106 */ 2107 remote_ip = ssh_remote_ipaddr(ssh); 2108 2109 #ifdef LIBWRAP 2110 /* Check whether logins are denied from this host. */ 2111 if (ssh_packet_connection_is_on_socket(ssh)) { 2112 struct request_info req; 2113 2114 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 2115 fromhost(&req); 2116 2117 if (!hosts_access(&req)) { 2118 debug("Connection refused by tcp wrapper"); 2119 refuse(&req); 2120 /* NOTREACHED */ 2121 fatal("libwrap refuse returns"); 2122 } 2123 } 2124 #endif /* LIBWRAP */ 2125 2126 rdomain = ssh_packet_rdomain_in(ssh); 2127 2128 /* Log the connection. */ 2129 laddr = get_local_ipaddr(sock_in); 2130 verbose("Connection from %s port %d on %s port %d%s%s%s", 2131 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2132 rdomain == NULL ? "" : " rdomain \"", 2133 rdomain == NULL ? "" : rdomain, 2134 rdomain == NULL ? "" : "\""); 2135 free(laddr); 2136 2137 /* set the HPN options for the child */ 2138 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size); 2139 2140 /* 2141 * We don't want to listen forever unless the other side 2142 * successfully authenticates itself. So we set up an alarm which is 2143 * cleared after successful authentication. A limit of zero 2144 * indicates no limit. Note that we don't set the alarm in debugging 2145 * mode; it is just annoying to have the server exit just when you 2146 * are about to discover the bug. 2147 */ 2148 ssh_signal(SIGALRM, grace_alarm_handler); 2149 if (!debug_flag) 2150 alarm(options.login_grace_time); 2151 2152 if ((r = kex_exchange_identification(ssh, -1, 2153 options.version_addendum)) != 0) 2154 sshpkt_fatal(ssh, r, "banner exchange"); 2155 2156 ssh_packet_set_nonblocking(ssh); 2157 2158 /* allocate authentication context */ 2159 authctxt = xcalloc(1, sizeof(*authctxt)); 2160 ssh->authctxt = authctxt; 2161 2162 /* XXX global for cleanup, access from other modules */ 2163 the_authctxt = authctxt; 2164 2165 /* Set default key authentication options */ 2166 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2167 fatal("allocation failed"); 2168 2169 /* prepare buffer to collect messages to display to user after login */ 2170 if ((loginmsg = sshbuf_new()) == NULL) 2171 fatal_f("sshbuf_new failed"); 2172 auth_debug_reset(); 2173 2174 if (use_privsep) { 2175 if (privsep_preauth(ssh) == 1) 2176 goto authenticated; 2177 } else if (have_agent) { 2178 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2179 error_r(r, "Unable to get agent socket"); 2180 have_agent = 0; 2181 } 2182 } 2183 2184 /* perform the key exchange */ 2185 /* authenticate user and start session */ 2186 do_ssh2_kex(ssh); 2187 do_authentication2(ssh); 2188 2189 /* 2190 * If we use privilege separation, the unprivileged child transfers 2191 * the current keystate and exits 2192 */ 2193 if (use_privsep) { 2194 mm_send_keystate(ssh, pmonitor); 2195 ssh_packet_clear_keys(ssh); 2196 exit(0); 2197 } 2198 2199 authenticated: 2200 /* 2201 * Cancel the alarm we set to limit the time taken for 2202 * authentication. 2203 */ 2204 alarm(0); 2205 ssh_signal(SIGALRM, SIG_DFL); 2206 authctxt->authenticated = 1; 2207 if (startup_pipe != -1) { 2208 close(startup_pipe); 2209 startup_pipe = -1; 2210 } 2211 2212 #ifdef USE_PAM 2213 if (options.use_pam) { 2214 do_pam_setcred(1); 2215 do_pam_session(ssh); 2216 } 2217 #endif 2218 2219 if (options.routing_domain != NULL) 2220 set_process_rdomain(ssh, options.routing_domain); 2221 2222 /* 2223 * In privilege separation, we fork another child and prepare 2224 * file descriptor passing. 2225 */ 2226 if (use_privsep) { 2227 privsep_postauth(ssh, authctxt); 2228 /* the monitor process [priv] will not return */ 2229 } 2230 2231 ssh_packet_set_timeout(ssh, options.client_alive_interval, 2232 options.client_alive_count_max); 2233 2234 /* Try to send all our hostkeys to the client */ 2235 notify_hostkeys(ssh); 2236 2237 /* Start session. */ 2238 do_authenticated(ssh, authctxt); 2239 2240 #ifdef USE_PAM 2241 if (options.use_pam) 2242 finish_pam(); 2243 #endif /* USE_PAM */ 2244 2245 /* The connection has been terminated. */ 2246 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 2247 verbose("Transferred: sent %llu, received %llu bytes", 2248 (unsigned long long)obytes, (unsigned long long)ibytes); 2249 2250 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2251 ssh_packet_close(ssh); 2252 2253 if (use_privsep) 2254 mm_terminate(); 2255 2256 exit(0); 2257 } 2258 2259 int 2260 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 2261 struct sshkey *pubkey, u_char **signature, size_t *slenp, 2262 const u_char *data, size_t dlen, const char *alg) 2263 { 2264 int r; 2265 2266 if (use_privsep) { 2267 if (privkey) { 2268 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 2269 data, dlen, alg, options.sk_provider, NULL, 2270 ssh->compat) < 0) 2271 fatal_f("privkey sign failed"); 2272 } else { 2273 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 2274 data, dlen, alg, options.sk_provider, NULL, 2275 ssh->compat) < 0) 2276 fatal_f("pubkey sign failed"); 2277 } 2278 } else { 2279 if (privkey) { 2280 if (sshkey_sign(privkey, signature, slenp, data, dlen, 2281 alg, options.sk_provider, NULL, ssh->compat) < 0) 2282 fatal_f("privkey sign failed"); 2283 } else { 2284 if ((r = ssh_agent_sign(auth_sock, pubkey, 2285 signature, slenp, data, dlen, alg, 2286 ssh->compat)) != 0) { 2287 fatal_fr(r, "agent sign failed"); 2288 } 2289 } 2290 } 2291 return 0; 2292 } 2293 2294 /* SSH2 key exchange */ 2295 static void 2296 do_ssh2_kex(struct ssh *ssh) 2297 { 2298 const char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2299 struct kex *kex; 2300 char *prop_kex = NULL, *prop_enc = NULL, *prop_hostkey = NULL; 2301 int r; 2302 2303 myproposal[PROPOSAL_KEX_ALGS] = prop_kex = compat_kex_proposal(ssh, 2304 options.kex_algorithms); 2305 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2306 myproposal[PROPOSAL_ENC_ALGS_STOC] = prop_enc = 2307 compat_cipher_proposal(ssh, options.ciphers); 2308 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2309 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2310 2311 if (options.compression == COMP_NONE) { 2312 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2313 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2314 } 2315 2316 if (options.rekey_limit || options.rekey_interval) 2317 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 2318 options.rekey_interval); 2319 2320 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = prop_hostkey = 2321 compat_pkalg_proposal(ssh, list_hostkey_types()); 2322 2323 /* start key exchange */ 2324 if ((r = kex_setup(ssh, myproposal)) != 0) 2325 fatal_r(r, "kex_setup"); 2326 kex = ssh->kex; 2327 #ifdef WITH_OPENSSL 2328 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 2329 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 2330 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 2331 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 2332 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 2333 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2334 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2335 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 2336 #endif 2337 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 2338 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; 2339 kex->load_host_public_key=&get_hostkey_public_by_type; 2340 kex->load_host_private_key=&get_hostkey_private_by_type; 2341 kex->host_key_index=&get_hostkey_index; 2342 kex->sign = sshd_hostkey_sign; 2343 2344 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 2345 2346 #ifdef DEBUG_KEXDH 2347 /* send 1st encrypted/maced/compressed message */ 2348 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 2349 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 2350 (r = sshpkt_send(ssh)) != 0 || 2351 (r = ssh_packet_write_wait(ssh)) != 0) 2352 fatal_fr(r, "send test"); 2353 #endif 2354 free(prop_kex); 2355 free(prop_enc); 2356 free(prop_hostkey); 2357 debug("KEX done"); 2358 } 2359 2360 /* server specific fatal cleanup */ 2361 void 2362 cleanup_exit(int i) 2363 { 2364 if (i == 255) 2365 pfilter_notify(1); 2366 2367 if (the_active_state != NULL && the_authctxt != NULL) { 2368 do_cleanup(the_active_state, the_authctxt); 2369 if (use_privsep && privsep_is_preauth && 2370 pmonitor != NULL && pmonitor->m_pid > 1) { 2371 debug("Killing privsep child %d", pmonitor->m_pid); 2372 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2373 errno != ESRCH) { 2374 error_f("kill(%d): %s", pmonitor->m_pid, 2375 strerror(errno)); 2376 } 2377 } 2378 } 2379 _exit(i); 2380 } 2381