1/* $NetBSD: sshd.c,v 1.50 2023/12/20 17:15:21 christos Exp $ */ 2/* $OpenBSD: sshd.c,v 1.601 2023/12/18 14:45:49 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 1.50 2023/12/20 17:15:21 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 "authfile.h" 94#include "pathnames.h" 95#include "atomicio.h" 96#include "canohost.h" 97#include "hostfile.h" 98#include "auth.h" 99#include "authfd.h" 100#include "misc.h" 101#include "msg.h" 102#include "dispatch.h" 103#include "channels.h" 104#include "session.h" 105#include "monitor.h" 106#ifdef GSSAPI 107#include "ssh-gss.h" 108#endif 109#include "monitor_wrap.h" 110#include "ssh-sandbox.h" 111#include "auth-options.h" 112#include "version.h" 113#include "ssherr.h" 114#include "sk-api.h" 115#include "srclimit.h" 116#include "dh.h" 117 118#include "pfilter.h" 119 120#ifdef LIBWRAP 121#include <tcpd.h> 122#include <syslog.h> 123int allow_severity = LOG_INFO; 124int deny_severity = LOG_WARNING; 125#endif /* LIBWRAP */ 126 127#ifdef WITH_LDAP_PUBKEY 128#include "ldapauth.h" 129#endif 130 131#ifndef HOST_NAME_MAX 132#define HOST_NAME_MAX MAXHOSTNAMELEN 133#endif 134 135/* Re-exec fds */ 136#define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 137#define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 138#define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 139#define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 140 141extern char *__progname; 142 143/* Server configuration options. */ 144ServerOptions options; 145 146/* Name of the server configuration file. */ 147const char *config_file_name = _PATH_SERVER_CONFIG_FILE; 148 149/* 150 * Debug mode flag. This can be set on the command line. If debug 151 * mode is enabled, extra debugging output will be sent to the system 152 * log, the daemon will not go to background, and will exit after processing 153 * the first connection. 154 */ 155int debug_flag = 0; 156 157/* 158 * Indicating that the daemon should only test the configuration and keys. 159 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 160 * configuration, optionally using connection information provided by the 161 * "-C" flag. 162 */ 163static int test_flag = 0; 164 165/* Flag indicating that the daemon is being started from inetd. */ 166static int inetd_flag = 0; 167 168/* Flag indicating that sshd should not detach and become a daemon. */ 169static int no_daemon_flag = 0; 170 171/* debug goes to stderr unless inetd_flag is set */ 172static int log_stderr = 0; 173 174/* Saved arguments to main(). */ 175static char **saved_argv; 176 177/* re-exec */ 178static int rexeced_flag = 0; 179static int rexec_flag = 1; 180static int rexec_argc = 0; 181static char **rexec_argv; 182 183/* 184 * The sockets that the server is listening; this is used in the SIGHUP 185 * signal handler. 186 */ 187#define MAX_LISTEN_SOCKS 16 188static int listen_socks[MAX_LISTEN_SOCKS]; 189static int num_listen_socks = 0; 190 191/* Daemon's agent connection */ 192int auth_sock = -1; 193static int have_agent = 0; 194 195/* 196 * Any really sensitive data in the application is contained in this 197 * structure. The idea is that this structure could be locked into memory so 198 * that the pages do not get written into swap. However, there are some 199 * problems. The private key contains BIGNUMs, and we do not (in principle) 200 * have access to the internals of them, and locking just the structure is 201 * not very useful. Currently, memory locking is not implemented. 202 */ 203struct { 204 struct sshkey **host_keys; /* all private host keys */ 205 struct sshkey **host_pubkeys; /* all public host keys */ 206 struct sshkey **host_certificates; /* all public host certificates */ 207 int have_ssh2_key; 208} sensitive_data; 209 210/* This is set to true when a signal is received. */ 211static volatile sig_atomic_t received_sighup = 0; 212static volatile sig_atomic_t received_sigterm = 0; 213 214/* record remote hostname or ip */ 215u_int utmp_len = HOST_NAME_MAX+1; 216 217/* 218 * startup_pipes/flags are used for tracking children of the listening sshd 219 * process early in their lifespans. This tracking is needed for three things: 220 * 221 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 222 * connections. 223 * 2) Avoiding a race condition for SIGHUP processing, where child processes 224 * may have listen_socks open that could collide with main listener process 225 * after it restarts. 226 * 3) Ensuring that rexec'd sshd processes have received their initial state 227 * from the parent listen process before handling SIGHUP. 228 * 229 * Child processes signal that they have completed closure of the listen_socks 230 * and (if applicable) received their rexec state by sending a char over their 231 * sock. Child processes signal that authentication has completed by closing 232 * the sock (or by exiting). 233 */ 234static int *startup_pipes = NULL; 235static int *startup_flags = NULL; /* Indicates child closed listener */ 236static int startup_pipe = -1; /* in child */ 237 238/* variables used for privilege separation */ 239int use_privsep = -1; 240struct monitor *pmonitor = NULL; 241int privsep_is_preauth = 1; 242 243/* global connection state and authentication contexts */ 244Authctxt *the_authctxt = NULL; 245struct ssh *the_active_state; 246 247/* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 248struct sshauthopt *auth_opts = NULL; 249 250/* sshd_config buffer */ 251struct sshbuf *cfg; 252 253/* Included files from the configuration file */ 254struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 255 256/* message to be displayed after login */ 257struct sshbuf *loginmsg; 258 259/* Prototypes for various functions defined later in this file. */ 260void destroy_sensitive_data(void); 261void demote_sensitive_data(void); 262static void do_ssh2_kex(struct ssh *); 263 264static char *listener_proctitle; 265 266/* 267 * Close all listening sockets 268 */ 269static void 270close_listen_socks(void) 271{ 272 int i; 273 274 for (i = 0; i < num_listen_socks; i++) 275 close(listen_socks[i]); 276 num_listen_socks = 0; 277} 278 279static void 280close_startup_pipes(void) 281{ 282 int i; 283 284 if (startup_pipes) 285 for (i = 0; i < options.max_startups; i++) 286 if (startup_pipes[i] != -1) 287 close(startup_pipes[i]); 288} 289 290/* 291 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 292 * the effect is to reread the configuration file (and to regenerate 293 * the server key). 294 */ 295 296static void 297sighup_handler(int sig) 298{ 299 received_sighup = 1; 300} 301 302/* 303 * Called from the main program after receiving SIGHUP. 304 * Restarts the server. 305 */ 306__dead static void 307sighup_restart(void) 308{ 309 logit("Received SIGHUP; restarting."); 310 if (options.pid_file != NULL) 311 unlink(options.pid_file); 312 close_listen_socks(); 313 close_startup_pipes(); 314 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 315 execv(saved_argv[0], saved_argv); 316 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 317 strerror(errno)); 318 exit(1); 319} 320 321/* 322 * Generic signal handler for terminating signals in the master daemon. 323 */ 324static void 325sigterm_handler(int sig) 326{ 327 received_sigterm = sig; 328} 329 330/* 331 * SIGCHLD handler. This is called whenever a child dies. This will then 332 * reap any zombies left by exited children. 333 */ 334static void 335main_sigchld_handler(int sig) 336{ 337 int save_errno = errno; 338 pid_t pid; 339 int status; 340 341 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 342 (pid == -1 && errno == EINTR)) 343 ; 344 errno = save_errno; 345} 346 347/* 348 * Signal handler for the alarm after the login grace period has expired. 349 */ 350/*ARGSUSED*/ 351__dead static void 352grace_alarm_handler(int sig) 353{ 354 pfilter_notify(1); 355 /* 356 * Try to kill any processes that we have spawned, E.g. authorized 357 * keys command helpers or privsep children. 358 */ 359 if (getpgid(0) == getpid()) { 360 ssh_signal(SIGTERM, SIG_IGN); 361 kill(0, SIGTERM); 362 } 363 364 /* Log error and exit. */ 365 sigdie("Timeout before authentication for %s port %d", 366 ssh_remote_ipaddr(the_active_state), 367 ssh_remote_port(the_active_state)); 368} 369 370/* Destroy the host and server keys. They will no longer be needed. */ 371void 372destroy_sensitive_data(void) 373{ 374 u_int i; 375 376 for (i = 0; i < options.num_host_key_files; i++) { 377 if (sensitive_data.host_keys[i]) { 378 sshkey_free(sensitive_data.host_keys[i]); 379 sensitive_data.host_keys[i] = NULL; 380 } 381 if (sensitive_data.host_certificates[i]) { 382 sshkey_free(sensitive_data.host_certificates[i]); 383 sensitive_data.host_certificates[i] = NULL; 384 } 385 } 386} 387 388/* Demote private to public keys for network child */ 389void 390demote_sensitive_data(void) 391{ 392 struct sshkey *tmp; 393 u_int i; 394 int r; 395 396 for (i = 0; i < options.num_host_key_files; i++) { 397 if (sensitive_data.host_keys[i]) { 398 if ((r = sshkey_from_private( 399 sensitive_data.host_keys[i], &tmp)) != 0) 400 fatal_r(r, "could not demote host %s key", 401 sshkey_type(sensitive_data.host_keys[i])); 402 sshkey_free(sensitive_data.host_keys[i]); 403 sensitive_data.host_keys[i] = tmp; 404 } 405 /* Certs do not need demotion */ 406 } 407} 408 409static void 410privsep_preauth_child(void) 411{ 412 gid_t gidset[1]; 413 struct passwd *pw; 414 415 /* Enable challenge-response authentication for privilege separation */ 416 privsep_challenge_enable(); 417 418#ifdef GSSAPI 419 /* Cache supported mechanism OIDs for later use */ 420 ssh_gssapi_prepare_supported_oids(); 421#endif 422 423 /* Demote the private keys to public keys. */ 424 demote_sensitive_data(); 425 426 /* Demote the child */ 427 if (getuid() == 0 || geteuid() == 0) { 428 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) 429 fatal("Privilege separation user %s does not exist", 430 SSH_PRIVSEP_USER); 431 pw = pwcopy(pw); /* Ensure mutable */ 432 endpwent(); 433 freezero(pw->pw_passwd, strlen(pw->pw_passwd)); 434 435 /* Change our root directory */ 436 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 437 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 438 strerror(errno)); 439 if (chdir("/") == -1) 440 fatal("chdir(\"/\"): %s", strerror(errno)); 441 442 /* 443 * Drop our privileges 444 * NB. Can't use setusercontext() after chroot. 445 */ 446 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, 447 (u_int)pw->pw_gid); 448 gidset[0] = pw->pw_gid; 449 if (setgroups(1, gidset) == -1) 450 fatal("setgroups: %.100s", strerror(errno)); 451 permanently_set_uid(pw); 452 } 453} 454 455static int 456privsep_preauth(struct ssh *ssh) 457{ 458 int status, r; 459 pid_t pid; 460 struct ssh_sandbox *box = NULL; 461 462 /* Set up unprivileged child process to deal with network data */ 463 pmonitor = monitor_init(); 464 /* Store a pointer to the kex for later rekeying */ 465 pmonitor->m_pkex = &ssh->kex; 466 467 if (use_privsep == PRIVSEP_ON) 468 box = ssh_sandbox_init(); 469 pid = fork(); 470 if (pid == -1) { 471 fatal("fork of unprivileged child failed"); 472 } else if (pid != 0) { 473 debug2("Network child is on pid %ld", (long)pid); 474 475 pmonitor->m_pid = pid; 476 if (have_agent) { 477 r = ssh_get_authentication_socket(&auth_sock); 478 if (r != 0) { 479 error_r(r, "Could not get agent socket"); 480 have_agent = 0; 481 } 482 } 483 if (box != NULL) 484 ssh_sandbox_parent_preauth(box, pid); 485 monitor_child_preauth(ssh, pmonitor); 486 487 /* Wait for the child's exit status */ 488 while (waitpid(pid, &status, 0) == -1) { 489 if (errno == EINTR) 490 continue; 491 pmonitor->m_pid = -1; 492 fatal_f("waitpid: %s", strerror(errno)); 493 } 494 privsep_is_preauth = 0; 495 pmonitor->m_pid = -1; 496 if (WIFEXITED(status)) { 497 if (WEXITSTATUS(status) != 0) 498 fatal_f("preauth child exited with status %d", 499 WEXITSTATUS(status)); 500 } else if (WIFSIGNALED(status)) 501 fatal_f("preauth child terminated by signal %d", 502 WTERMSIG(status)); 503 if (box != NULL) 504 ssh_sandbox_parent_finish(box); 505 return 1; 506 } else { 507 /* child */ 508 close(pmonitor->m_sendfd); 509 close(pmonitor->m_log_recvfd); 510 511 /* Arrange for logging to be sent to the monitor */ 512 set_log_handler(mm_log_handler, pmonitor); 513 514 privsep_preauth_child(); 515 setproctitle("%s", "[net]"); 516 if (box != NULL) 517 ssh_sandbox_child(box); 518 519 return 0; 520 } 521} 522 523static void 524privsep_postauth(struct ssh *ssh, Authctxt *authctxt) 525{ 526 ssh->authctxt = authctxt; 527 if (authctxt->pw->pw_uid == 0) { 528 /* File descriptor passing is broken or root login */ 529 use_privsep = 0; 530 goto skip; 531 } 532 533 /* New socket pair */ 534 monitor_reinit(pmonitor); 535 536 pmonitor->m_pid = fork(); 537 if (pmonitor->m_pid == -1) 538 fatal("fork of unprivileged child failed"); 539 else if (pmonitor->m_pid != 0) { 540 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 541 sshbuf_reset(loginmsg); 542 monitor_clear_keystate(ssh, pmonitor); 543 monitor_child_postauth(ssh, pmonitor); 544 545 /* NEVERREACHED */ 546 exit(0); 547 } 548 549 /* child */ 550 551 close(pmonitor->m_sendfd); 552 pmonitor->m_sendfd = -1; 553 554 /* Demote the private keys to public keys. */ 555 demote_sensitive_data(); 556 557 /* Drop privileges */ 558 do_setusercontext(authctxt->pw); 559 560 skip: 561 /* It is safe now to apply the key state */ 562 monitor_apply_keystate(ssh, pmonitor); 563 564 /* 565 * Tell the packet layer that authentication was successful, since 566 * this information is not part of the key state. 567 */ 568 ssh_packet_set_authenticated(ssh); 569} 570 571static void 572append_hostkey_type(struct sshbuf *b, const char *s) 573{ 574 int r; 575 576 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 577 debug3_f("%s key not permitted by HostkeyAlgorithms", s); 578 return; 579 } 580 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 581 fatal_fr(r, "sshbuf_putf"); 582} 583 584static char * 585list_hostkey_types(void) 586{ 587 struct sshbuf *b; 588 struct sshkey *key; 589 char *ret; 590 u_int i; 591 592 if ((b = sshbuf_new()) == NULL) 593 fatal_f("sshbuf_new failed"); 594 for (i = 0; i < options.num_host_key_files; i++) { 595 key = sensitive_data.host_keys[i]; 596 if (key == NULL) 597 key = sensitive_data.host_pubkeys[i]; 598 if (key == NULL) 599 continue; 600 switch (key->type) { 601 case KEY_RSA: 602 /* for RSA we also support SHA2 signatures */ 603 append_hostkey_type(b, "rsa-sha2-512"); 604 append_hostkey_type(b, "rsa-sha2-256"); 605 /* FALLTHROUGH */ 606 case KEY_DSA: 607 case KEY_ECDSA: 608 case KEY_ED25519: 609 case KEY_ECDSA_SK: 610 case KEY_ED25519_SK: 611 case KEY_XMSS: 612 append_hostkey_type(b, sshkey_ssh_name(key)); 613 break; 614 } 615 /* If the private key has a cert peer, then list that too */ 616 key = sensitive_data.host_certificates[i]; 617 if (key == NULL) 618 continue; 619 switch (key->type) { 620 case KEY_RSA_CERT: 621 /* for RSA we also support SHA2 signatures */ 622 append_hostkey_type(b, 623 "rsa-sha2-512-cert-v01@openssh.com"); 624 append_hostkey_type(b, 625 "rsa-sha2-256-cert-v01@openssh.com"); 626 /* FALLTHROUGH */ 627 case KEY_DSA_CERT: 628 case KEY_ECDSA_CERT: 629 case KEY_ED25519_CERT: 630 case KEY_ECDSA_SK_CERT: 631 case KEY_ED25519_SK_CERT: 632 case KEY_XMSS_CERT: 633 append_hostkey_type(b, sshkey_ssh_name(key)); 634 break; 635 } 636 } 637 if ((ret = sshbuf_dup_string(b)) == NULL) 638 fatal_f("sshbuf_dup_string failed"); 639 sshbuf_free(b); 640 debug_f("%s", ret); 641 return ret; 642} 643 644static struct sshkey * 645get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 646{ 647 u_int i; 648 struct sshkey *key; 649 650 for (i = 0; i < options.num_host_key_files; i++) { 651 switch (type) { 652 case KEY_RSA_CERT: 653 case KEY_DSA_CERT: 654 case KEY_ECDSA_CERT: 655 case KEY_ED25519_CERT: 656 case KEY_ECDSA_SK_CERT: 657 case KEY_ED25519_SK_CERT: 658 case KEY_XMSS_CERT: 659 key = sensitive_data.host_certificates[i]; 660 break; 661 default: 662 key = sensitive_data.host_keys[i]; 663 if (key == NULL && !need_private) 664 key = sensitive_data.host_pubkeys[i]; 665 break; 666 } 667 if (key == NULL || key->type != type) 668 continue; 669 switch (type) { 670 case KEY_ECDSA: 671 case KEY_ECDSA_SK: 672 case KEY_ECDSA_CERT: 673 case KEY_ECDSA_SK_CERT: 674 if (key->ecdsa_nid != nid) 675 continue; 676 /* FALLTHROUGH */ 677 default: 678 return need_private ? 679 sensitive_data.host_keys[i] : key; 680 } 681 } 682 return NULL; 683} 684 685struct sshkey * 686get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 687{ 688 return get_hostkey_by_type(type, nid, 0, ssh); 689} 690 691struct sshkey * 692get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 693{ 694 return get_hostkey_by_type(type, nid, 1, ssh); 695} 696 697struct sshkey * 698get_hostkey_by_index(int ind) 699{ 700 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 701 return (NULL); 702 return (sensitive_data.host_keys[ind]); 703} 704 705struct sshkey * 706get_hostkey_public_by_index(int ind, struct ssh *ssh) 707{ 708 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 709 return (NULL); 710 return (sensitive_data.host_pubkeys[ind]); 711} 712 713int 714get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 715{ 716 u_int i; 717 718 for (i = 0; i < options.num_host_key_files; i++) { 719 if (sshkey_is_cert(key)) { 720 if (key == sensitive_data.host_certificates[i] || 721 (compare && sensitive_data.host_certificates[i] && 722 sshkey_equal(key, 723 sensitive_data.host_certificates[i]))) 724 return (i); 725 } else { 726 if (key == sensitive_data.host_keys[i] || 727 (compare && sensitive_data.host_keys[i] && 728 sshkey_equal(key, sensitive_data.host_keys[i]))) 729 return (i); 730 if (key == sensitive_data.host_pubkeys[i] || 731 (compare && sensitive_data.host_pubkeys[i] && 732 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 733 return (i); 734 } 735 } 736 return (-1); 737} 738 739/* Inform the client of all hostkeys */ 740static void 741notify_hostkeys(struct ssh *ssh) 742{ 743 struct sshbuf *buf; 744 struct sshkey *key; 745 u_int i, nkeys; 746 int r; 747 char *fp; 748 749 /* Some clients cannot cope with the hostkeys message, skip those. */ 750 if (ssh->compat & SSH_BUG_HOSTKEYS) 751 return; 752 753 if ((buf = sshbuf_new()) == NULL) 754 fatal_f("sshbuf_new"); 755 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 756 key = get_hostkey_public_by_index(i, ssh); 757 if (key == NULL || key->type == KEY_UNSPEC || 758 sshkey_is_cert(key)) 759 continue; 760 fp = sshkey_fingerprint(key, options.fingerprint_hash, 761 SSH_FP_DEFAULT); 762 debug3_f("key %d: %s %s", i, sshkey_ssh_name(key), fp); 763 free(fp); 764 if (nkeys == 0) { 765 /* 766 * Start building the request when we find the 767 * first usable key. 768 */ 769 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 770 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || 771 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ 772 sshpkt_fatal(ssh, r, "%s: start request", __func__); 773 } 774 /* Append the key to the request */ 775 sshbuf_reset(buf); 776 if ((r = sshkey_putb(key, buf)) != 0) 777 fatal_fr(r, "couldn't put hostkey %d", i); 778 if ((r = sshpkt_put_stringb(ssh, buf)) != 0) 779 sshpkt_fatal(ssh, r, "%s: append key", __func__); 780 nkeys++; 781 } 782 debug3_f("sent %u hostkeys", nkeys); 783 if (nkeys == 0) 784 fatal_f("no hostkeys"); 785 if ((r = sshpkt_send(ssh)) != 0) 786 sshpkt_fatal(ssh, r, "%s: send", __func__); 787 sshbuf_free(buf); 788} 789 790/* 791 * returns 1 if connection should be dropped, 0 otherwise. 792 * dropping starts at connection #max_startups_begin with a probability 793 * of (max_startups_rate/100). the probability increases linearly until 794 * all connections are dropped for startups > max_startups 795 */ 796static int 797should_drop_connection(int startups) 798{ 799 int p, r; 800 801 if (startups < options.max_startups_begin) 802 return 0; 803 if (startups >= options.max_startups) 804 return 1; 805 if (options.max_startups_rate == 100) 806 return 1; 807 808 p = 100 - options.max_startups_rate; 809 p *= startups - options.max_startups_begin; 810 p /= options.max_startups - options.max_startups_begin; 811 p += options.max_startups_rate; 812 r = arc4random_uniform(100); 813 814 debug_f("p %d, r %d", p, r); 815 return (r < p) ? 1 : 0; 816} 817 818/* 819 * Check whether connection should be accepted by MaxStartups. 820 * Returns 0 if the connection is accepted. If the connection is refused, 821 * returns 1 and attempts to send notification to client. 822 * Logs when the MaxStartups condition is entered or exited, and periodically 823 * while in that state. 824 */ 825static int 826drop_connection(int sock, int startups, int notify_pipe) 827{ 828 char *laddr, *raddr; 829 const char msg[] = "Exceeded MaxStartups\r\n"; 830 static time_t last_drop, first_drop; 831 static u_int ndropped; 832 LogLevel drop_level = SYSLOG_LEVEL_VERBOSE; 833 time_t now; 834 835 now = monotime(); 836 if (!should_drop_connection(startups) && 837 srclimit_check_allow(sock, notify_pipe) == 1) { 838 if (last_drop != 0 && 839 startups < options.max_startups_begin - 1) { 840 /* XXX maybe need better hysteresis here */ 841 logit("exited MaxStartups throttling after %s, " 842 "%u connections dropped", 843 fmt_timeframe(now - first_drop), ndropped); 844 last_drop = 0; 845 } 846 return 0; 847 } 848 849#define SSHD_MAXSTARTUPS_LOG_INTERVAL (5 * 60) 850 if (last_drop == 0) { 851 error("beginning MaxStartups throttling"); 852 drop_level = SYSLOG_LEVEL_INFO; 853 first_drop = now; 854 ndropped = 0; 855 } else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) { 856 /* Periodic logs */ 857 error("in MaxStartups throttling for %s, " 858 "%u connections dropped", 859 fmt_timeframe(now - first_drop), ndropped + 1); 860 drop_level = SYSLOG_LEVEL_INFO; 861 } 862 last_drop = now; 863 ndropped++; 864 865 laddr = get_local_ipaddr(sock); 866 raddr = get_peer_ipaddr(sock); 867 do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d " 868 "past MaxStartups", startups, raddr, get_peer_port(sock), 869 laddr, get_local_port(sock)); 870 free(laddr); 871 free(raddr); 872 /* best-effort notification to client */ 873 (void)write(sock, msg, sizeof(msg) - 1); 874 return 1; 875} 876 877__dead static void 878usage(void) 879{ 880 fprintf(stderr, "%s, %s\n", SSH_VERSION, SSH_OPENSSL_VERSION); 881 fprintf(stderr, 882"usage: sshd [-46DdeGiqTtV] [-C connection_spec] [-c host_cert_file]\n" 883" [-E log_file] [-f config_file] [-g login_grace_time]\n" 884" [-h host_key_file] [-o option] [-p port] [-u len]\n" 885 ); 886 exit(1); 887} 888 889static void 890send_rexec_state(int fd, struct sshbuf *conf) 891{ 892 struct sshbuf *m = NULL, *inc = NULL; 893 struct include_item *item = NULL; 894 int r; 895 896 debug3_f("entering fd = %d config len %zu", fd, 897 sshbuf_len(conf)); 898 899 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 900 fatal_f("sshbuf_new failed"); 901 902 /* pack includes into a string */ 903 TAILQ_FOREACH(item, &includes, entry) { 904 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 905 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 906 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 907 fatal_fr(r, "compose includes"); 908 } 909 910 /* 911 * Protocol from reexec master to child: 912 * string configuration 913 * string included_files[] { 914 * string selector 915 * string filename 916 * string contents 917 * } 918 */ 919 if ((r = sshbuf_put_stringb(m, conf)) != 0 || 920 (r = sshbuf_put_stringb(m, inc)) != 0) 921 fatal_fr(r, "compose config"); 922 if (ssh_msg_send(fd, 0, m) == -1) 923 error_f("ssh_msg_send failed"); 924 925 sshbuf_free(m); 926 sshbuf_free(inc); 927 928 debug3_f("done"); 929} 930 931static void 932recv_rexec_state(int fd, struct sshbuf *conf) 933{ 934 struct sshbuf *m, *inc; 935 u_char *cp, ver; 936 size_t len; 937 int r; 938 struct include_item *item; 939 940 debug3_f("entering fd = %d", fd); 941 942 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 943 fatal_f("sshbuf_new failed"); 944 if (ssh_msg_recv(fd, m) == -1) 945 fatal_f("ssh_msg_recv failed"); 946 if ((r = sshbuf_get_u8(m, &ver)) != 0) 947 fatal_fr(r, "parse version"); 948 if (ver != 0) 949 fatal_f("rexec version mismatch"); 950 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || 951 (r = sshbuf_get_stringb(m, inc)) != 0) 952 fatal_fr(r, "parse config"); 953 954 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 955 fatal_fr(r, "sshbuf_put"); 956 957 while (sshbuf_len(inc) != 0) { 958 item = xcalloc(1, sizeof(*item)); 959 if ((item->contents = sshbuf_new()) == NULL) 960 fatal_f("sshbuf_new failed"); 961 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 || 962 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 || 963 (r = sshbuf_get_stringb(inc, item->contents)) != 0) 964 fatal_fr(r, "parse includes"); 965 TAILQ_INSERT_TAIL(&includes, item, entry); 966 } 967 968 free(cp); 969 sshbuf_free(m); 970 971 debug3_f("done"); 972} 973 974/* Accept a connection from inetd */ 975static void 976server_accept_inetd(int *sock_in, int *sock_out) 977{ 978 if (rexeced_flag) { 979 close(REEXEC_CONFIG_PASS_FD); 980 *sock_in = *sock_out = dup(STDIN_FILENO); 981 } else { 982 *sock_in = dup(STDIN_FILENO); 983 *sock_out = dup(STDOUT_FILENO); 984 } 985 /* 986 * We intentionally do not close the descriptors 0, 1, and 2 987 * as our code for setting the descriptors won't work if 988 * ttyfd happens to be one of those. 989 */ 990 if (stdfd_devnull(1, 1, !log_stderr) == -1) 991 error_f("stdfd_devnull failed"); 992 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 993} 994 995/* 996 * Listen for TCP connections 997 */ 998static void 999listen_on_addrs(struct listenaddr *la) 1000{ 1001 int ret, listen_sock; 1002 struct addrinfo *ai; 1003 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1004 int socksize; 1005 socklen_t socksizelen = sizeof(int); 1006 1007 for (ai = la->addrs; ai; ai = ai->ai_next) { 1008 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1009 continue; 1010 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1011 fatal("Too many listen sockets. " 1012 "Enlarge MAX_LISTEN_SOCKS"); 1013 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1014 ntop, sizeof(ntop), strport, sizeof(strport), 1015 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1016 error("getnameinfo failed: %.100s", 1017 ssh_gai_strerror(ret)); 1018 continue; 1019 } 1020 /* Create socket for listening. */ 1021 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1022 ai->ai_protocol); 1023 if (listen_sock == -1) { 1024 /* kernel may not support ipv6 */ 1025 verbose("socket: %.100s", strerror(errno)); 1026 continue; 1027 } 1028 if (set_nonblock(listen_sock) == -1) { 1029 close(listen_sock); 1030 continue; 1031 } 1032 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1033 verbose("socket: CLOEXEC: %s", strerror(errno)); 1034 close(listen_sock); 1035 continue; 1036 } 1037 /* Socket options */ 1038 set_reuseaddr(listen_sock); 1039 if (la->rdomain != NULL && 1040 set_rdomain(listen_sock, la->rdomain) == -1) { 1041 close(listen_sock); 1042 continue; 1043 } 1044 1045 debug("Bind to port %s on %s.", strport, ntop); 1046 1047 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, 1048 &socksize, &socksizelen); 1049 debug("Server TCP RWIN socket size: %d", socksize); 1050 debug("HPN Buffer Size: %d", options.hpn_buffer_size); 1051 1052 /* Bind the socket to the desired port. */ 1053 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 1054 error("Bind to port %s on %s failed: %.200s.", 1055 strport, ntop, strerror(errno)); 1056 close(listen_sock); 1057 continue; 1058 } 1059 listen_socks[num_listen_socks] = listen_sock; 1060 num_listen_socks++; 1061 1062 /* Start listening on the port. */ 1063 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 1064 fatal("listen on [%s]:%s: %.100s", 1065 ntop, strport, strerror(errno)); 1066 logit("Server listening on %s port %s%s%s.", 1067 ntop, strport, 1068 la->rdomain == NULL ? "" : " rdomain ", 1069 la->rdomain == NULL ? "" : la->rdomain); 1070 } 1071} 1072 1073static void 1074server_listen(void) 1075{ 1076 u_int i; 1077 1078 /* Initialise per-source limit tracking. */ 1079 srclimit_init(options.max_startups, options.per_source_max_startups, 1080 options.per_source_masklen_ipv4, options.per_source_masklen_ipv6); 1081 1082 for (i = 0; i < options.num_listen_addrs; i++) { 1083 listen_on_addrs(&options.listen_addrs[i]); 1084 freeaddrinfo(options.listen_addrs[i].addrs); 1085 free(options.listen_addrs[i].rdomain); 1086 memset(&options.listen_addrs[i], 0, 1087 sizeof(options.listen_addrs[i])); 1088 } 1089 free(options.listen_addrs); 1090 options.listen_addrs = NULL; 1091 options.num_listen_addrs = 0; 1092 1093 if (!num_listen_socks) 1094 fatal("Cannot bind any address."); 1095} 1096 1097/* 1098 * The main TCP accept loop. Note that, for the non-debug case, returns 1099 * from this function are in a forked subprocess. 1100 */ 1101static void 1102server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1103{ 1104 struct pollfd *pfd = NULL; 1105 int i, j, ret, npfd; 1106 int ostartups = -1, startups = 0, listening = 0, lameduck = 0; 1107 int startup_p[2] = { -1 , -1 }, *startup_pollfd; 1108 char c = 0; 1109 struct sockaddr_storage from; 1110 socklen_t fromlen; 1111 pid_t pid; 1112 sigset_t nsigset, osigset; 1113 1114 /* setup fd set for accept */ 1115 /* pipes connected to unauthenticated child sshd processes */ 1116 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1117 startup_flags = xcalloc(options.max_startups, sizeof(int)); 1118 startup_pollfd = xcalloc(options.max_startups, sizeof(int)); 1119 for (i = 0; i < options.max_startups; i++) 1120 startup_pipes[i] = -1; 1121 1122 pfilter_init(); 1123 /* 1124 * Prepare signal mask that we use to block signals that might set 1125 * received_sigterm or received_sighup, so that we are guaranteed 1126 * to immediately wake up the ppoll if a signal is received after 1127 * the flag is checked. 1128 */ 1129 sigemptyset(&nsigset); 1130 sigaddset(&nsigset, SIGHUP); 1131 sigaddset(&nsigset, SIGCHLD); 1132 sigaddset(&nsigset, SIGTERM); 1133 sigaddset(&nsigset, SIGQUIT); 1134 1135 /* sized for worst-case */ 1136 pfd = xcalloc(num_listen_socks + options.max_startups, 1137 sizeof(struct pollfd)); 1138 1139 /* 1140 * Stay listening for connections until the system crashes or 1141 * the daemon is killed with a signal. 1142 */ 1143 for (;;) { 1144 sigprocmask(SIG_BLOCK, &nsigset, &osigset); 1145 if (received_sigterm) { 1146 logit("Received signal %d; terminating.", 1147 (int) received_sigterm); 1148 close_listen_socks(); 1149 if (options.pid_file != NULL) 1150 unlink(options.pid_file); 1151 exit(received_sigterm == SIGTERM ? 0 : 255); 1152 } 1153 if (ostartups != startups) { 1154 setproctitle("%s [listener] %d of %d-%d startups", 1155 listener_proctitle, startups, 1156 options.max_startups_begin, options.max_startups); 1157 ostartups = startups; 1158 } 1159 if (received_sighup) { 1160 if (!lameduck) { 1161 debug("Received SIGHUP; waiting for children"); 1162 close_listen_socks(); 1163 lameduck = 1; 1164 } 1165 if (listening <= 0) { 1166 sigprocmask(SIG_SETMASK, &osigset, NULL); 1167 sighup_restart(); 1168 } 1169 } 1170 1171 for (i = 0; i < num_listen_socks; i++) { 1172 pfd[i].fd = listen_socks[i]; 1173 pfd[i].events = POLLIN; 1174 } 1175 npfd = num_listen_socks; 1176 for (i = 0; i < options.max_startups; i++) { 1177 startup_pollfd[i] = -1; 1178 if (startup_pipes[i] != -1) { 1179 pfd[npfd].fd = startup_pipes[i]; 1180 pfd[npfd].events = POLLIN; 1181 startup_pollfd[i] = npfd++; 1182 } 1183 } 1184 1185 /* Wait until a connection arrives or a child exits. */ 1186 ret = ppoll(pfd, npfd, NULL, &osigset); 1187 if (ret == -1 && errno != EINTR) { 1188 error("ppoll: %.100s", strerror(errno)); 1189 if (errno == EINVAL) 1190 cleanup_exit(1); /* can't recover */ 1191 } 1192 sigprocmask(SIG_SETMASK, &osigset, NULL); 1193 if (ret == -1) 1194 continue; 1195 1196 for (i = 0; i < options.max_startups; i++) { 1197 if (startup_pipes[i] == -1 || 1198 startup_pollfd[i] == -1 || 1199 !(pfd[startup_pollfd[i]].revents & (POLLIN|POLLHUP))) 1200 continue; 1201 switch (read(startup_pipes[i], &c, sizeof(c))) { 1202 case -1: 1203 if (errno == EINTR || errno == EAGAIN) 1204 continue; 1205 if (errno != EPIPE) { 1206 error_f("startup pipe %d (fd=%d): " 1207 "read %s", i, startup_pipes[i], 1208 strerror(errno)); 1209 } 1210 /* FALLTHROUGH */ 1211 case 0: 1212 /* child exited or completed auth */ 1213 close(startup_pipes[i]); 1214 srclimit_done(startup_pipes[i]); 1215 startup_pipes[i] = -1; 1216 startups--; 1217 if (startup_flags[i]) 1218 listening--; 1219 break; 1220 case 1: 1221 /* child has finished preliminaries */ 1222 if (startup_flags[i]) { 1223 listening--; 1224 startup_flags[i] = 0; 1225 } 1226 break; 1227 } 1228 } 1229 for (i = 0; i < num_listen_socks; i++) { 1230 if (!(pfd[i].revents & POLLIN)) 1231 continue; 1232 fromlen = sizeof(from); 1233 *newsock = accept(listen_socks[i], 1234 (struct sockaddr *)&from, &fromlen); 1235 if (*newsock == -1) { 1236 if (errno != EINTR && errno != EWOULDBLOCK && 1237 errno != ECONNABORTED) 1238 error("accept: %.100s", 1239 strerror(errno)); 1240 if (errno == EMFILE || errno == ENFILE) 1241 usleep(100 * 1000); 1242 continue; 1243 } 1244 if (unset_nonblock(*newsock) == -1) { 1245 close(*newsock); 1246 continue; 1247 } 1248 if (pipe(startup_p) == -1) { 1249 error_f("pipe(startup_p): %s", strerror(errno)); 1250 close(*newsock); 1251 continue; 1252 } 1253 if (drop_connection(*newsock, startups, startup_p[0])) { 1254 close(*newsock); 1255 close(startup_p[0]); 1256 close(startup_p[1]); 1257 continue; 1258 } 1259 1260 if (rexec_flag && socketpair(AF_UNIX, 1261 SOCK_STREAM, 0, config_s) == -1) { 1262 error("reexec socketpair: %s", 1263 strerror(errno)); 1264 close(*newsock); 1265 close(startup_p[0]); 1266 close(startup_p[1]); 1267 continue; 1268 } 1269 1270 for (j = 0; j < options.max_startups; j++) 1271 if (startup_pipes[j] == -1) { 1272 startup_pipes[j] = startup_p[0]; 1273 startups++; 1274 startup_flags[j] = 1; 1275 break; 1276 } 1277 1278 /* 1279 * Got connection. Fork a child to handle it, unless 1280 * we are in debugging mode. 1281 */ 1282 if (debug_flag) { 1283 /* 1284 * In debugging mode. Close the listening 1285 * socket, and start processing the 1286 * connection without forking. 1287 */ 1288 debug("Server will not fork when running in debugging mode."); 1289 close_listen_socks(); 1290 *sock_in = *newsock; 1291 *sock_out = *newsock; 1292 close(startup_p[0]); 1293 close(startup_p[1]); 1294 startup_pipe = -1; 1295 pid = getpid(); 1296 if (rexec_flag) { 1297 send_rexec_state(config_s[0], cfg); 1298 close(config_s[0]); 1299 } 1300 free(pfd); 1301 return; 1302 } 1303 1304 /* 1305 * Normal production daemon. Fork, and have 1306 * the child process the connection. The 1307 * parent continues listening. 1308 */ 1309 listening++; 1310 if ((pid = fork()) == 0) { 1311 /* 1312 * Child. Close the listening and 1313 * max_startup sockets. Start using 1314 * the accepted socket. Reinitialize 1315 * logging (since our pid has changed). 1316 * We return from this function to handle 1317 * the connection. 1318 */ 1319 startup_pipe = startup_p[1]; 1320 close_startup_pipes(); 1321 close_listen_socks(); 1322 *sock_in = *newsock; 1323 *sock_out = *newsock; 1324 log_init(__progname, 1325 options.log_level, 1326 options.log_facility, 1327 log_stderr); 1328 if (rexec_flag) 1329 close(config_s[0]); 1330 else { 1331 /* 1332 * Signal parent that the preliminaries 1333 * for this child are complete. For the 1334 * re-exec case, this happens after the 1335 * child has received the rexec state 1336 * from the server. 1337 */ 1338 (void)atomicio(vwrite, startup_pipe, 1339 __UNCONST("\0"), 1); 1340 } 1341 free(pfd); 1342 return; 1343 } 1344 1345 /* Parent. Stay in the loop. */ 1346 if (pid == -1) 1347 error("fork: %.100s", strerror(errno)); 1348 else 1349 debug("Forked child %ld.", (long)pid); 1350 1351 close(startup_p[1]); 1352 1353 if (rexec_flag) { 1354 close(config_s[1]); 1355 send_rexec_state(config_s[0], cfg); 1356 close(config_s[0]); 1357 } 1358 close(*newsock); 1359 } 1360 } 1361} 1362 1363/* 1364 * If IP options are supported, make sure there are none (log and 1365 * return an error if any are found). Basically we are worried about 1366 * source routing; it can be used to pretend you are somebody 1367 * (ip-address) you are not. That itself may be "almost acceptable" 1368 * under certain circumstances, but rhosts authentication is useless 1369 * if source routing is accepted. Notice also that if we just dropped 1370 * source routing here, the other side could use IP spoofing to do 1371 * rest of the interaction and could still bypass security. So we 1372 * exit here if we detect any IP options. 1373 */ 1374static void 1375check_ip_options(struct ssh *ssh) 1376{ 1377 int sock_in = ssh_packet_get_connection_in(ssh); 1378 struct sockaddr_storage from; 1379 socklen_t fromlen = sizeof(from); 1380#ifdef IP_OPTIONS 1381 socklen_t option_size, i; 1382 u_char opts[200]; 1383 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1384 char text[sizeof(opts) * 3 + 1]; 1385#endif 1386 1387 memset(&from, 0, sizeof(from)); 1388 if (getpeername(sock_in, (struct sockaddr *)&from, 1389 &fromlen) == -1) 1390 return; 1391 if (from.ss_family != AF_INET) 1392 return; 1393 /* XXX IPv6 options? */ 1394#ifdef IP_OPTIONS 1395 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1396 &option_size) >= 0 && option_size != 0) { 1397 text[0] = '\0'; 1398 for (i = 0; i < option_size; i++) 1399 snprintf(text + i*3, sizeof(text) - i*3, 1400 " %2.2x", opts[i]); 1401 fatal("Connection from %.100s port %d with IP opts: %.800s", 1402 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1403 } 1404#endif 1405 return; 1406} 1407 1408/* Set the routing domain for this process */ 1409#if !defined(__OpenBSD__) 1410__dead 1411#endif 1412static void 1413set_process_rdomain(struct ssh *ssh, const char *name) 1414{ 1415#if defined(__OpenBSD__) 1416 int rtable, ortable = getrtable(); 1417 const char *errstr; 1418 1419 if (name == NULL) 1420 return; /* default */ 1421 1422 if (strcmp(name, "%D") == 0) { 1423 /* "expands" to routing domain of connection */ 1424 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1425 return; 1426 } 1427 1428 rtable = (int)strtonum(name, 0, 255, &errstr); 1429 if (errstr != NULL) /* Shouldn't happen */ 1430 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1431 if (rtable != ortable && setrtable(rtable) != 0) 1432 fatal("Unable to set routing domain %d: %s", 1433 rtable, strerror(errno)); 1434 debug_f("set routing domain %d (was %d)", rtable, ortable); 1435#else /* defined(__OpenBSD__) */ 1436 fatal("Unable to set routing domain: not supported in this platform"); 1437#endif 1438} 1439 1440static void 1441accumulate_host_timing_secret(struct sshbuf *server_cfg, 1442 struct sshkey *key) 1443{ 1444 static struct ssh_digest_ctx *ctx; 1445 u_char *hash; 1446 size_t len; 1447 struct sshbuf *buf; 1448 int r; 1449 1450 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1451 fatal_f("ssh_digest_start"); 1452 if (key == NULL) { /* finalize */ 1453 /* add server config in case we are using agent for host keys */ 1454 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1455 sshbuf_len(server_cfg)) != 0) 1456 fatal_f("ssh_digest_update"); 1457 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1458 hash = xmalloc(len); 1459 if (ssh_digest_final(ctx, hash, len) != 0) 1460 fatal_f("ssh_digest_final"); 1461 options.timing_secret = PEEK_U64(hash); 1462 freezero(hash, len); 1463 ssh_digest_free(ctx); 1464 ctx = NULL; 1465 return; 1466 } 1467 if ((buf = sshbuf_new()) == NULL) 1468 fatal_f("could not allocate buffer"); 1469 if ((r = sshkey_private_serialize(key, buf)) != 0) 1470 fatal_fr(r, "encode %s key", sshkey_ssh_name(key)); 1471 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1472 fatal_f("ssh_digest_update"); 1473 sshbuf_reset(buf); 1474 sshbuf_free(buf); 1475} 1476 1477static char * 1478prepare_proctitle(int ac, char **av) 1479{ 1480 char *ret = NULL; 1481 int i; 1482 1483 for (i = 0; i < ac; i++) 1484 xextendf(&ret, " ", "%s", av[i]); 1485 return ret; 1486} 1487 1488__dead static void 1489print_config(struct ssh *ssh, struct connection_info *connection_info) 1490{ 1491 /* 1492 * If no connection info was provided by -C then use 1493 * use a blank one that will cause no predicate to match. 1494 */ 1495 if (connection_info == NULL) 1496 connection_info = get_connection_info(ssh, 0, 0); 1497 connection_info->test = 1; 1498 parse_server_match_config(&options, &includes, connection_info); 1499 dump_config(&options); 1500 exit(0); 1501} 1502 1503/* 1504 * Main program for the daemon. 1505 */ 1506int 1507main(int ac, char **av) 1508{ 1509 struct ssh *ssh = NULL; 1510 extern char *optarg; 1511 extern int optind; 1512 int r, opt, on = 1, do_dump_cfg = 0, already_daemon, remote_port; 1513 int sock_in = -1, sock_out = -1, newsock = -1; 1514 const char *remote_ip, *rdomain; 1515 char *fp, *line, *laddr, *logfile = NULL; 1516 int config_s[2] = { -1 , -1 }; 1517 u_int i, j; 1518 u_int64_t ibytes, obytes; 1519 mode_t new_umask; 1520 struct sshkey *key; 1521 struct sshkey *pubkey; 1522 int keytype; 1523 Authctxt *authctxt; 1524 struct connection_info *connection_info = NULL; 1525 sigset_t sigmask; 1526 1527 sigemptyset(&sigmask); 1528 sigprocmask(SIG_SETMASK, &sigmask, NULL); 1529 1530 /* Save argv. */ 1531 saved_argv = av; 1532 rexec_argc = ac; 1533 1534 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1535 sanitise_stdfd(); 1536 1537 /* Initialize configuration options to their default values. */ 1538 initialize_server_options(&options); 1539 1540 /* Parse command-line arguments. */ 1541 while ((opt = getopt(ac, av, 1542 "C:E:b:c:f:g:h:k:o:p:u:46DGQRTdeiqrtV")) != -1) { 1543 switch (opt) { 1544 case '4': 1545 options.address_family = AF_INET; 1546 break; 1547 case '6': 1548 options.address_family = AF_INET6; 1549 break; 1550 case 'f': 1551 config_file_name = optarg; 1552 break; 1553 case 'c': 1554 servconf_add_hostcert("[command-line]", 0, 1555 &options, optarg); 1556 break; 1557 case 'd': 1558 if (debug_flag == 0) { 1559 debug_flag = 1; 1560 options.log_level = SYSLOG_LEVEL_DEBUG1; 1561 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1562 options.log_level++; 1563 break; 1564 case 'D': 1565 no_daemon_flag = 1; 1566 break; 1567 case 'G': 1568 do_dump_cfg = 1; 1569 break; 1570 case 'E': 1571 logfile = optarg; 1572 /* FALLTHROUGH */ 1573 case 'e': 1574 log_stderr = 1; 1575 break; 1576 case 'i': 1577 inetd_flag = 1; 1578 break; 1579 case 'r': 1580 rexec_flag = 0; 1581 break; 1582 case 'R': 1583 rexeced_flag = 1; 1584 inetd_flag = 1; 1585 break; 1586 case 'Q': 1587 /* ignored */ 1588 break; 1589 case 'q': 1590 options.log_level = SYSLOG_LEVEL_QUIET; 1591 break; 1592 case 'b': 1593 /* protocol 1, ignored */ 1594 break; 1595 case 'p': 1596 options.ports_from_cmdline = 1; 1597 if (options.num_ports >= MAX_PORTS) { 1598 fprintf(stderr, "too many ports.\n"); 1599 exit(1); 1600 } 1601 options.ports[options.num_ports++] = a2port(optarg); 1602 if (options.ports[options.num_ports-1] <= 0) { 1603 fprintf(stderr, "Bad port number.\n"); 1604 exit(1); 1605 } 1606 break; 1607 case 'g': 1608 if ((options.login_grace_time = convtime(optarg)) == -1) { 1609 fprintf(stderr, "Invalid login grace time.\n"); 1610 exit(1); 1611 } 1612 break; 1613 case 'k': 1614 /* protocol 1, ignored */ 1615 break; 1616 case 'h': 1617 servconf_add_hostkey("[command-line]", 0, 1618 &options, optarg, 1); 1619 break; 1620 case 't': 1621 test_flag = 1; 1622 break; 1623 case 'T': 1624 test_flag = 2; 1625 break; 1626 case 'C': 1627 connection_info = get_connection_info(ssh, 0, 0); 1628 if (parse_server_match_testspec(connection_info, 1629 optarg) == -1) 1630 exit(1); 1631 break; 1632 case 'u': 1633 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1634 if (utmp_len > HOST_NAME_MAX+1) { 1635 fprintf(stderr, "Invalid utmp length.\n"); 1636 exit(1); 1637 } 1638 break; 1639 case 'o': 1640 line = xstrdup(optarg); 1641 if (process_server_config_line(&options, line, 1642 "command-line", 0, NULL, NULL, &includes) != 0) 1643 exit(1); 1644 free(line); 1645 break; 1646 case 'V': 1647 fprintf(stderr, "%s, %s\n", 1648 SSH_VERSION, SSH_OPENSSL_VERSION); 1649 exit(0); 1650 default: 1651 usage(); 1652 break; 1653 } 1654 } 1655 if (rexeced_flag || inetd_flag) 1656 rexec_flag = 0; 1657 if (!test_flag && !do_dump_cfg && rexec_flag && !path_absolute(av[0])) 1658 fatal("sshd re-exec requires execution with an absolute path"); 1659 if (rexeced_flag) 1660 r = closefrom(REEXEC_MIN_FREE_FD); 1661 else 1662 r = closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1663 if (r == -1) 1664 fatal("closefrom failed: %.200s", strerror(errno)); 1665 1666#ifdef WITH_OPENSSL 1667 OpenSSL_add_all_algorithms(); 1668#endif 1669 1670 /* If requested, redirect the logs to the specified logfile. */ 1671 if (logfile != NULL) 1672 log_redirect_stderr_to(logfile); 1673 /* 1674 * Force logging to stderr until we have loaded the private host 1675 * key (unless started from inetd) 1676 */ 1677 log_init(__progname, 1678 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1679 SYSLOG_LEVEL_INFO : options.log_level, 1680 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1681 SYSLOG_FACILITY_AUTH : options.log_facility, 1682 log_stderr || !inetd_flag || debug_flag); 1683 1684 sensitive_data.have_ssh2_key = 0; 1685 1686 /* 1687 * If we're not doing an extended test do not silently ignore connection 1688 * test params. 1689 */ 1690 if (test_flag < 2 && connection_info != NULL) 1691 fatal("Config test connection parameter (-C) provided without " 1692 "test mode (-T)"); 1693 1694 /* Fetch our configuration */ 1695 if ((cfg = sshbuf_new()) == NULL) 1696 fatal_f("sshbuf_new failed"); 1697 if (rexeced_flag) { 1698 setproctitle("%s", "[rexeced]"); 1699 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1700 if (!debug_flag) { 1701 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1702 close(REEXEC_STARTUP_PIPE_FD); 1703 /* 1704 * Signal parent that this child is at a point where 1705 * they can go away if they have a SIGHUP pending. 1706 */ 1707 (void)atomicio(vwrite, startup_pipe, __UNCONST("\0"), 1); 1708 } 1709 } else if (strcasecmp(config_file_name, "none") != 0) 1710 load_server_config(config_file_name, cfg); 1711 1712 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1713 cfg, &includes, NULL, rexeced_flag); 1714 1715#ifdef WITH_OPENSSL 1716 if (options.moduli_file != NULL) 1717 dh_set_moduli_file(options.moduli_file); 1718#endif 1719 1720 /* Fill in default values for those options not explicitly set. */ 1721 fill_default_server_options(&options); 1722 1723 /* Check that options are sensible */ 1724 if (options.authorized_keys_command_user == NULL && 1725 (options.authorized_keys_command != NULL && 1726 strcasecmp(options.authorized_keys_command, "none") != 0)) 1727 fatal("AuthorizedKeysCommand set without " 1728 "AuthorizedKeysCommandUser"); 1729 if (options.authorized_principals_command_user == NULL && 1730 (options.authorized_principals_command != NULL && 1731 strcasecmp(options.authorized_principals_command, "none") != 0)) 1732 fatal("AuthorizedPrincipalsCommand set without " 1733 "AuthorizedPrincipalsCommandUser"); 1734 1735 /* 1736 * Check whether there is any path through configured auth methods. 1737 * Unfortunately it is not possible to verify this generally before 1738 * daemonisation in the presence of Match block, but this catches 1739 * and warns for trivial misconfigurations that could break login. 1740 */ 1741 if (options.num_auth_methods != 0) { 1742 for (i = 0; i < options.num_auth_methods; i++) { 1743 if (auth2_methods_valid(options.auth_methods[i], 1744 1) == 0) 1745 break; 1746 } 1747 if (i >= options.num_auth_methods) 1748 fatal("AuthenticationMethods cannot be satisfied by " 1749 "enabled authentication methods"); 1750 } 1751 1752 /* Check that there are no remaining arguments. */ 1753 if (optind < ac) { 1754 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1755 exit(1); 1756 } 1757 1758#ifdef WITH_LDAP_PUBKEY 1759 /* ldap_options_print(&options.lpk); */ 1760 /* XXX initialize/check ldap connection and set *LD */ 1761 if (options.lpk.on) { 1762 if (options.lpk.l_conf && (ldap_parse_lconf(&options.lpk) < 0) ) 1763 error("[LDAP] could not parse %s", options.lpk.l_conf); 1764 if (ldap_xconnect(&options.lpk) < 0) 1765 error("[LDAP] could not initialize ldap connection"); 1766 } 1767#endif 1768 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION); 1769 1770 if (do_dump_cfg) 1771 print_config(ssh, connection_info); 1772 1773 /* load host keys */ 1774 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1775 sizeof(struct sshkey *)); 1776 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1777 sizeof(struct sshkey *)); 1778 1779 if (options.host_key_agent) { 1780 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1781 setenv(SSH_AUTHSOCKET_ENV_NAME, 1782 options.host_key_agent, 1); 1783 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1784 have_agent = 1; 1785 else 1786 error_r(r, "Could not connect to agent \"%s\"", 1787 options.host_key_agent); 1788 } 1789 1790 for (i = 0; i < options.num_host_key_files; i++) { 1791 int ll = options.host_key_file_userprovided[i] ? 1792 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1793 1794 if (options.host_key_files[i] == NULL) 1795 continue; 1796 if ((r = sshkey_load_private(options.host_key_files[i], "", 1797 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1798 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1799 options.host_key_files[i]); 1800 if (sshkey_is_sk(key) && 1801 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1802 debug("host key %s requires user presence, ignoring", 1803 options.host_key_files[i]); 1804 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1805 } 1806 if (r == 0 && key != NULL && 1807 (r = sshkey_shield_private(key)) != 0) { 1808 do_log2_r(r, ll, "Unable to shield host key \"%s\"", 1809 options.host_key_files[i]); 1810 sshkey_free(key); 1811 key = NULL; 1812 } 1813 if ((r = sshkey_load_public(options.host_key_files[i], 1814 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1815 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1816 options.host_key_files[i]); 1817 if (pubkey != NULL && key != NULL) { 1818 if (!sshkey_equal(pubkey, key)) { 1819 error("Public key for %s does not match " 1820 "private key", options.host_key_files[i]); 1821 sshkey_free(pubkey); 1822 pubkey = NULL; 1823 } 1824 } 1825 if (pubkey == NULL && key != NULL) { 1826 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1827 fatal_r(r, "Could not demote key: \"%s\"", 1828 options.host_key_files[i]); 1829 } 1830 if (pubkey != NULL && (r = sshkey_check_rsa_length(pubkey, 1831 options.required_rsa_size)) != 0) { 1832 error_fr(r, "Host key %s", options.host_key_files[i]); 1833 sshkey_free(pubkey); 1834 sshkey_free(key); 1835 continue; 1836 } 1837 sensitive_data.host_keys[i] = key; 1838 sensitive_data.host_pubkeys[i] = pubkey; 1839 1840 if (key == NULL && pubkey != NULL && have_agent) { 1841 debug("will rely on agent for hostkey %s", 1842 options.host_key_files[i]); 1843 keytype = pubkey->type; 1844 } else if (key != NULL) { 1845 keytype = key->type; 1846 accumulate_host_timing_secret(cfg, key); 1847 } else { 1848 do_log2(ll, "Unable to load host key: %s", 1849 options.host_key_files[i]); 1850 sensitive_data.host_keys[i] = NULL; 1851 sensitive_data.host_pubkeys[i] = NULL; 1852 continue; 1853 } 1854 1855 switch (keytype) { 1856 case KEY_RSA: 1857 case KEY_DSA: 1858 case KEY_ECDSA: 1859 case KEY_ED25519: 1860 case KEY_ECDSA_SK: 1861 case KEY_ED25519_SK: 1862 case KEY_XMSS: 1863 if (have_agent || key != NULL) 1864 sensitive_data.have_ssh2_key = 1; 1865 break; 1866 } 1867 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1868 SSH_FP_DEFAULT)) == NULL) 1869 fatal("sshkey_fingerprint failed"); 1870 debug("%s host key #%d: %s %s", 1871 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1872 free(fp); 1873 } 1874 accumulate_host_timing_secret(cfg, NULL); 1875 if (!sensitive_data.have_ssh2_key) { 1876 logit("sshd: no hostkeys available -- exiting."); 1877 exit(1); 1878 } 1879 1880 /* 1881 * Load certificates. They are stored in an array at identical 1882 * indices to the public keys that they relate to. 1883 */ 1884 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1885 sizeof(struct sshkey *)); 1886 for (i = 0; i < options.num_host_key_files; i++) 1887 sensitive_data.host_certificates[i] = NULL; 1888 1889 for (i = 0; i < options.num_host_cert_files; i++) { 1890 if (options.host_cert_files[i] == NULL) 1891 continue; 1892 if ((r = sshkey_load_public(options.host_cert_files[i], 1893 &key, NULL)) != 0) { 1894 error_r(r, "Could not load host certificate \"%s\"", 1895 options.host_cert_files[i]); 1896 continue; 1897 } 1898 if (!sshkey_is_cert(key)) { 1899 error("Certificate file is not a certificate: %s", 1900 options.host_cert_files[i]); 1901 sshkey_free(key); 1902 continue; 1903 } 1904 /* Find matching private key */ 1905 for (j = 0; j < options.num_host_key_files; j++) { 1906 if (sshkey_equal_public(key, 1907 sensitive_data.host_pubkeys[j])) { 1908 sensitive_data.host_certificates[j] = key; 1909 break; 1910 } 1911 } 1912 if (j >= options.num_host_key_files) { 1913 error("No matching private key for certificate: %s", 1914 options.host_cert_files[i]); 1915 sshkey_free(key); 1916 continue; 1917 } 1918 sensitive_data.host_certificates[j] = key; 1919 debug("host certificate: #%u type %d %s", j, key->type, 1920 sshkey_type(key)); 1921 } 1922 1923 if (use_privsep) { 1924 struct stat st; 1925 1926 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1927 fatal("Privilege separation user %s does not exist", 1928 SSH_PRIVSEP_USER); 1929 endpwent(); 1930 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1931 (S_ISDIR(st.st_mode) == 0)) 1932 fatal("Missing privilege separation directory: %s", 1933 _PATH_PRIVSEP_CHROOT_DIR); 1934 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1935 fatal("%s must be owned by root and not group or " 1936 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1937 } 1938 1939 if (test_flag > 1) 1940 print_config(ssh, connection_info); 1941 1942 /* Configuration looks good, so exit if in test mode. */ 1943 if (test_flag) 1944 exit(0); 1945 1946 if (rexec_flag) { 1947 if (rexec_argc < 0) 1948 fatal("rexec_argc %d < 0", rexec_argc); 1949 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1950 for (i = 0; i < (u_int)rexec_argc; i++) { 1951 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1952 rexec_argv[i] = saved_argv[i]; 1953 } 1954 rexec_argv[rexec_argc] = __UNCONST("-R"); 1955 rexec_argv[rexec_argc + 1] = NULL; 1956 } 1957 listener_proctitle = prepare_proctitle(ac, av); 1958 1959 /* Ensure that umask disallows at least group and world write */ 1960 new_umask = umask(0077) | 0022; 1961 (void) umask(new_umask); 1962 1963 /* Initialize the log (it is reinitialized below in case we forked). */ 1964 if (debug_flag && (!inetd_flag || rexeced_flag)) 1965 log_stderr = 1; 1966 log_init(__progname, options.log_level, 1967 options.log_facility, log_stderr); 1968 for (i = 0; i < options.num_log_verbose; i++) 1969 log_verbose_add(options.log_verbose[i]); 1970 1971 /* 1972 * If not in debugging mode, not started from inetd and not already 1973 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1974 * terminal, and fork. The original process exits. 1975 */ 1976 already_daemon = daemonized(); 1977 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1978 1979 if (daemon(0, 0) == -1) 1980 fatal("daemon() failed: %.200s", strerror(errno)); 1981 1982 disconnect_controlling_tty(); 1983 } 1984 /* Reinitialize the log (because of the fork above). */ 1985 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1986 1987 /* 1988 * Chdir to the root directory so that the current disk can be 1989 * unmounted if desired. 1990 */ 1991 if (chdir("/") == -1) 1992 error("chdir(\"/\"): %s", strerror(errno)); 1993 1994 /* ignore SIGPIPE */ 1995 ssh_signal(SIGPIPE, SIG_IGN); 1996 1997 /* Get a connection, either from inetd or a listening TCP socket */ 1998 if (inetd_flag) { 1999 server_accept_inetd(&sock_in, &sock_out); 2000 } else { 2001 server_listen(); 2002 2003 ssh_signal(SIGHUP, sighup_handler); 2004 ssh_signal(SIGCHLD, main_sigchld_handler); 2005 ssh_signal(SIGTERM, sigterm_handler); 2006 ssh_signal(SIGQUIT, sigterm_handler); 2007 2008 /* 2009 * Write out the pid file after the sigterm handler 2010 * is setup and the listen sockets are bound 2011 */ 2012 if (options.pid_file != NULL && !debug_flag) { 2013 FILE *f = fopen(options.pid_file, "w"); 2014 2015 if (f == NULL) { 2016 error("Couldn't create pid file \"%s\": %s", 2017 options.pid_file, strerror(errno)); 2018 } else { 2019 fprintf(f, "%ld\n", (long) getpid()); 2020 fclose(f); 2021 } 2022 } 2023 2024 /* Accept a connection and return in a forked child */ 2025 server_accept_loop(&sock_in, &sock_out, 2026 &newsock, config_s); 2027 } 2028 2029 /* This is the child processing a new connection. */ 2030 setproctitle("%s", "[accepted]"); 2031 2032 /* 2033 * Create a new session and process group since the 4.4BSD 2034 * setlogin() affects the entire process group. We don't 2035 * want the child to be able to affect the parent. 2036 */ 2037 if (!debug_flag && !inetd_flag && setsid() == -1) 2038 error("setsid: %.100s", strerror(errno)); 2039 2040 if (rexec_flag) { 2041 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 2042 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2043 if (dup2(newsock, STDIN_FILENO) == -1) 2044 debug3_f("dup2 stdin: %s", strerror(errno)); 2045 if (dup2(STDIN_FILENO, STDOUT_FILENO) == -1) 2046 debug3_f("dup2 stdout: %s", strerror(errno)); 2047 if (startup_pipe == -1) 2048 close(REEXEC_STARTUP_PIPE_FD); 2049 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 2050 if (dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD) == -1) 2051 debug3_f("dup2 startup_p: %s", strerror(errno)); 2052 close(startup_pipe); 2053 startup_pipe = REEXEC_STARTUP_PIPE_FD; 2054 } 2055 2056 if (dup2(config_s[1], REEXEC_CONFIG_PASS_FD) == -1) 2057 debug3_f("dup2 config_s: %s", strerror(errno)); 2058 close(config_s[1]); 2059 2060 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 2061 execv(rexec_argv[0], rexec_argv); 2062 2063 /* Reexec has failed, fall back and continue */ 2064 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 2065 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 2066 log_init(__progname, options.log_level, 2067 options.log_facility, log_stderr); 2068 2069 /* Clean up fds */ 2070 close(REEXEC_CONFIG_PASS_FD); 2071 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2072 if (stdfd_devnull(1, 1, 0) == -1) 2073 error_f("stdfd_devnull failed"); 2074 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2075 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2076 } 2077 2078 /* Executed child processes don't need these. */ 2079 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2080 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2081 2082 /* We will not restart on SIGHUP since it no longer makes sense. */ 2083 ssh_signal(SIGALRM, SIG_DFL); 2084 ssh_signal(SIGHUP, SIG_DFL); 2085 ssh_signal(SIGTERM, SIG_DFL); 2086 ssh_signal(SIGQUIT, SIG_DFL); 2087 ssh_signal(SIGCHLD, SIG_DFL); 2088 2089 /* 2090 * Register our connection. This turns encryption off because we do 2091 * not have a key. 2092 */ 2093 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 2094 fatal("Unable to create connection"); 2095 the_active_state = ssh; 2096 ssh_packet_set_server(ssh); 2097 2098 check_ip_options(ssh); 2099 2100 /* Prepare the channels layer */ 2101 channel_init_channels(ssh); 2102 channel_set_af(ssh, options.address_family); 2103 process_channel_timeouts(ssh, &options); 2104 process_permitopen(ssh, &options); 2105 2106 /* Set SO_KEEPALIVE if requested. */ 2107 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 2108 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) 2109 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2110 2111 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2112 debug("ssh_remote_port failed"); 2113 cleanup_exit(255); 2114 } 2115 2116 /* 2117 * The rest of the code depends on the fact that 2118 * ssh_remote_ipaddr() caches the remote ip, even if 2119 * the socket goes away. 2120 */ 2121 remote_ip = ssh_remote_ipaddr(ssh); 2122 2123#ifdef LIBWRAP 2124 /* Check whether logins are denied from this host. */ 2125 if (ssh_packet_connection_is_on_socket(ssh)) { 2126 struct request_info req; 2127 2128 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 2129 fromhost(&req); 2130 2131 if (!hosts_access(&req)) { 2132 debug("Connection refused by tcp wrapper"); 2133 refuse(&req); 2134 /* NOTREACHED */ 2135 fatal("libwrap refuse returns"); 2136 } 2137 } 2138#endif /* LIBWRAP */ 2139 2140 rdomain = ssh_packet_rdomain_in(ssh); 2141 2142 /* Log the connection. */ 2143 laddr = get_local_ipaddr(sock_in); 2144 verbose("Connection from %s port %d on %s port %d%s%s%s", 2145 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2146 rdomain == NULL ? "" : " rdomain \"", 2147 rdomain == NULL ? "" : rdomain, 2148 rdomain == NULL ? "" : "\""); 2149 free(laddr); 2150 2151 /* set the HPN options for the child */ 2152 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size); 2153 2154 /* 2155 * We don't want to listen forever unless the other side 2156 * successfully authenticates itself. So we set up an alarm which is 2157 * cleared after successful authentication. A limit of zero 2158 * indicates no limit. Note that we don't set the alarm in debugging 2159 * mode; it is just annoying to have the server exit just when you 2160 * are about to discover the bug. 2161 */ 2162 ssh_signal(SIGALRM, grace_alarm_handler); 2163 if (!debug_flag) 2164 alarm(options.login_grace_time); 2165 2166 if ((r = kex_exchange_identification(ssh, -1, 2167 options.version_addendum)) != 0) 2168 sshpkt_fatal(ssh, r, "banner exchange"); 2169 2170 ssh_packet_set_nonblocking(ssh); 2171 2172 /* allocate authentication context */ 2173 authctxt = xcalloc(1, sizeof(*authctxt)); 2174 ssh->authctxt = authctxt; 2175 2176 /* XXX global for cleanup, access from other modules */ 2177 the_authctxt = authctxt; 2178 2179 /* Set default key authentication options */ 2180 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2181 fatal("allocation failed"); 2182 2183 /* prepare buffer to collect messages to display to user after login */ 2184 if ((loginmsg = sshbuf_new()) == NULL) 2185 fatal_f("sshbuf_new failed"); 2186 auth_debug_reset(); 2187 2188 if (use_privsep) { 2189 if (privsep_preauth(ssh) == 1) 2190 goto authenticated; 2191 } else if (have_agent) { 2192 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2193 error_r(r, "Unable to get agent socket"); 2194 have_agent = 0; 2195 } 2196 } 2197 2198 /* perform the key exchange */ 2199 /* authenticate user and start session */ 2200 do_ssh2_kex(ssh); 2201 do_authentication2(ssh); 2202 2203 /* 2204 * If we use privilege separation, the unprivileged child transfers 2205 * the current keystate and exits 2206 */ 2207 if (use_privsep) { 2208 mm_send_keystate(ssh, pmonitor); 2209 ssh_packet_clear_keys(ssh); 2210 exit(0); 2211 } 2212 2213 authenticated: 2214 /* 2215 * Cancel the alarm we set to limit the time taken for 2216 * authentication. 2217 */ 2218 alarm(0); 2219 ssh_signal(SIGALRM, SIG_DFL); 2220 authctxt->authenticated = 1; 2221 if (startup_pipe != -1) { 2222 close(startup_pipe); 2223 startup_pipe = -1; 2224 } 2225 2226#ifdef USE_PAM 2227 if (options.use_pam) { 2228 do_pam_setcred(1); 2229 do_pam_session(ssh); 2230 } 2231#endif 2232 2233 if (options.routing_domain != NULL) 2234 set_process_rdomain(ssh, options.routing_domain); 2235 2236 /* 2237 * In privilege separation, we fork another child and prepare 2238 * file descriptor passing. 2239 */ 2240 if (use_privsep) { 2241 privsep_postauth(ssh, authctxt); 2242 /* the monitor process [priv] will not return */ 2243 } 2244 2245 ssh_packet_set_timeout(ssh, options.client_alive_interval, 2246 options.client_alive_count_max); 2247 2248 /* Try to send all our hostkeys to the client */ 2249 notify_hostkeys(ssh); 2250 2251 /* Start session. */ 2252 do_authenticated(ssh, authctxt); 2253 2254#ifdef USE_PAM 2255 if (options.use_pam) 2256 finish_pam(); 2257#endif /* USE_PAM */ 2258 2259 /* The connection has been terminated. */ 2260 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 2261 verbose("Transferred: sent %llu, received %llu bytes", 2262 (unsigned long long)obytes, (unsigned long long)ibytes); 2263 2264 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2265 ssh_packet_close(ssh); 2266 2267 if (use_privsep) 2268 mm_terminate(); 2269 2270 exit(0); 2271} 2272 2273int 2274sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 2275 struct sshkey *pubkey, u_char **signature, size_t *slenp, 2276 const u_char *data, size_t dlen, const char *alg) 2277{ 2278 int r; 2279 2280 if (use_privsep) { 2281 if (privkey) { 2282 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 2283 data, dlen, alg, options.sk_provider, NULL, 2284 ssh->compat) < 0) 2285 fatal_f("privkey sign failed"); 2286 } else { 2287 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 2288 data, dlen, alg, options.sk_provider, NULL, 2289 ssh->compat) < 0) 2290 fatal_f("pubkey sign failed"); 2291 } 2292 } else { 2293 if (privkey) { 2294 if (sshkey_sign(privkey, signature, slenp, data, dlen, 2295 alg, options.sk_provider, NULL, ssh->compat) < 0) 2296 fatal_f("privkey sign failed"); 2297 } else { 2298 if ((r = ssh_agent_sign(auth_sock, pubkey, 2299 signature, slenp, data, dlen, alg, 2300 ssh->compat)) != 0) { 2301 fatal_fr(r, "agent sign failed"); 2302 } 2303 } 2304 } 2305 return 0; 2306} 2307 2308/* SSH2 key exchange */ 2309static void 2310do_ssh2_kex(struct ssh *ssh) 2311{ 2312 char *hkalgs = NULL, *myproposal[PROPOSAL_MAX]; 2313 const char *compression = NULL; 2314 struct kex *kex; 2315 int r; 2316 2317 if (options.rekey_limit || options.rekey_interval) 2318 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 2319 options.rekey_interval); 2320 2321 if (options.compression == COMP_NONE) 2322 compression = "none"; 2323 hkalgs = list_hostkey_types(); 2324 2325 kex_proposal_populate_entries(ssh, myproposal, options.kex_algorithms, 2326 options.ciphers, options.macs, compression, hkalgs); 2327 2328 free(hkalgs); 2329 2330 /* start key exchange */ 2331 if ((r = kex_setup(ssh, myproposal)) != 0) 2332 fatal_r(r, "kex_setup"); 2333 kex_set_server_sig_algs(ssh, options.pubkey_accepted_algos); 2334 kex = ssh->kex; 2335 2336#ifdef WITH_OPENSSL 2337 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 2338 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 2339 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 2340 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 2341 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 2342 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2343 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2344 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 2345#endif 2346 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 2347 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; 2348 kex->load_host_public_key=&get_hostkey_public_by_type; 2349 kex->load_host_private_key=&get_hostkey_private_by_type; 2350 kex->host_key_index=&get_hostkey_index; 2351 kex->sign = sshd_hostkey_sign; 2352 2353 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 2354 2355#ifdef DEBUG_KEXDH 2356 /* send 1st encrypted/maced/compressed message */ 2357 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 2358 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 2359 (r = sshpkt_send(ssh)) != 0 || 2360 (r = ssh_packet_write_wait(ssh)) != 0) 2361 fatal_fr(r, "send test"); 2362#endif 2363 kex_proposal_free_entries(myproposal); 2364 debug("KEX done"); 2365} 2366 2367/* server specific fatal cleanup */ 2368void 2369cleanup_exit(int i) 2370{ 2371 if (i == 255) 2372 pfilter_notify(1); 2373 2374 if (the_active_state != NULL && the_authctxt != NULL) { 2375 do_cleanup(the_active_state, the_authctxt); 2376 if (use_privsep && privsep_is_preauth && 2377 pmonitor != NULL && pmonitor->m_pid > 1) { 2378 debug("Killing privsep child %d", pmonitor->m_pid); 2379 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2380 errno != ESRCH) { 2381 error_f("kill(%d): %s", pmonitor->m_pid, 2382 strerror(errno)); 2383 } 2384 } 2385 } 2386 _exit(i); 2387} 2388