1/* $OpenBSD: sshd.c,v 1.516 2018/09/21 12:23:17 djm Exp $ */ 2/* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This program is the ssh daemon. It listens for connections from clients, 7 * and performs authentication, executes use commands or shell, and forwards 8 * information to/from the application to the user client over an encrypted 9 * connection. This can also handle forwarding of X11, TCP/IP, and 10 * authentication agent connections. 11 * 12 * As far as I am concerned, the code I have written for this software 13 * can be used freely for any purpose. Any derived versions of this 14 * software must be clearly marked as such, and if the derived work is 15 * incompatible with the protocol description in the RFC file, it must be 16 * called by a name other than "ssh" or "Secure Shell". 17 * 18 * SSH2 implementation: 19 * Privilege Separation: 20 * 21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 22 * Copyright (c) 2002 Niels Provos. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 43 */ 44 45#include "includes.h" 46__RCSID("$FreeBSD$"); 47 48#include <sys/types.h> 49#include <sys/ioctl.h> 50#include <sys/mman.h> 51#include <sys/socket.h> 52#ifdef HAVE_SYS_STAT_H 53# include <sys/stat.h> 54#endif 55#ifdef HAVE_SYS_TIME_H 56# include <sys/time.h> 57#endif 58#include "openbsd-compat/sys-tree.h" 59#include "openbsd-compat/sys-queue.h" 60#include <sys/wait.h> 61 62#include <errno.h> 63#include <fcntl.h> 64#include <netdb.h> 65#ifdef HAVE_PATHS_H 66#include <paths.h> 67#endif 68#include <grp.h> 69#include <pwd.h> 70#include <signal.h> 71#include <stdarg.h> 72#include <stdio.h> 73#include <stdlib.h> 74#include <string.h> 75#include <unistd.h> 76#include <limits.h> 77 78#ifdef WITH_OPENSSL 79#include <openssl/dh.h> 80#include <openssl/bn.h> 81#include <openssl/rand.h> 82#include "openbsd-compat/openssl-compat.h" 83#endif 84 85#ifdef HAVE_SECUREWARE 86#include <sys/security.h> 87#include <prot.h> 88#endif 89 90#ifdef __FreeBSD__ 91#include <resolv.h> 92#if defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H) 93#include <gssapi/gssapi.h> 94#elif defined(GSSAPI) && defined(HAVE_GSSAPI_H) 95#include <gssapi.h> 96#endif 97#endif 98 99#include "xmalloc.h" 100#include "ssh.h" 101#include "ssh2.h" 102#include "sshpty.h" 103#include "packet.h" 104#include "log.h" 105#include "sshbuf.h" 106#include "misc.h" 107#include "match.h" 108#include "servconf.h" 109#include "uidswap.h" 110#include "compat.h" 111#include "cipher.h" 112#include "digest.h" 113#include "sshkey.h" 114#include "kex.h" 115#include "myproposal.h" 116#include "authfile.h" 117#include "pathnames.h" 118#include "atomicio.h" 119#include "canohost.h" 120#include "hostfile.h" 121#include "auth.h" 122#include "authfd.h" 123#include "msg.h" 124#include "dispatch.h" 125#include "channels.h" 126#include "session.h" 127#include "monitor.h" 128#ifdef GSSAPI 129#include "ssh-gss.h" 130#endif 131#include "monitor_wrap.h" 132#include "ssh-sandbox.h" 133#include "auth-options.h" 134#include "version.h" 135#include "ssherr.h" 136#include "blacklist_client.h" 137 138#ifdef LIBWRAP 139#include <tcpd.h> 140#include <syslog.h> 141int allow_severity; 142int deny_severity; 143#endif /* LIBWRAP */ 144 145/* Re-exec fds */ 146#define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 147#define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 148#define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 149#define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 150 151extern char *__progname; 152 153/* Server configuration options. */ 154ServerOptions options; 155 156/* Name of the server configuration file. */ 157char *config_file_name = _PATH_SERVER_CONFIG_FILE; 158 159/* 160 * Debug mode flag. This can be set on the command line. If debug 161 * mode is enabled, extra debugging output will be sent to the system 162 * log, the daemon will not go to background, and will exit after processing 163 * the first connection. 164 */ 165int debug_flag = 0; 166 167/* 168 * Indicating that the daemon should only test the configuration and keys. 169 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 170 * configuration, optionally using connection information provided by the 171 * "-C" flag. 172 */ 173int test_flag = 0; 174 175/* Flag indicating that the daemon is being started from inetd. */ 176int inetd_flag = 0; 177 178/* Flag indicating that sshd should not detach and become a daemon. */ 179int no_daemon_flag = 0; 180 181/* debug goes to stderr unless inetd_flag is set */ 182int log_stderr = 0; 183 184/* Saved arguments to main(). */ 185char **saved_argv; 186int saved_argc; 187 188/* re-exec */ 189int rexeced_flag = 0; 190int rexec_flag = 1; 191int rexec_argc = 0; 192char **rexec_argv; 193 194/* 195 * The sockets that the server is listening; this is used in the SIGHUP 196 * signal handler. 197 */ 198#define MAX_LISTEN_SOCKS 16 199int listen_socks[MAX_LISTEN_SOCKS]; 200int num_listen_socks = 0; 201 202/* 203 * the client's version string, passed by sshd2 in compat mode. if != NULL, 204 * sshd will skip the version-number exchange 205 */ 206char *client_version_string = NULL; 207char *server_version_string = NULL; 208 209/* Daemon's agent connection */ 210int auth_sock = -1; 211int have_agent = 0; 212 213/* 214 * Any really sensitive data in the application is contained in this 215 * structure. The idea is that this structure could be locked into memory so 216 * that the pages do not get written into swap. However, there are some 217 * problems. The private key contains BIGNUMs, and we do not (in principle) 218 * have access to the internals of them, and locking just the structure is 219 * not very useful. Currently, memory locking is not implemented. 220 */ 221struct { 222 struct sshkey **host_keys; /* all private host keys */ 223 struct sshkey **host_pubkeys; /* all public host keys */ 224 struct sshkey **host_certificates; /* all public host certificates */ 225 int have_ssh2_key; 226} sensitive_data; 227 228/* This is set to true when a signal is received. */ 229static volatile sig_atomic_t received_sighup = 0; 230static volatile sig_atomic_t received_sigterm = 0; 231 232/* session identifier, used by RSA-auth */ 233u_char session_id[16]; 234 235/* same for ssh2 */ 236u_char *session_id2 = NULL; 237u_int session_id2_len = 0; 238 239/* record remote hostname or ip */ 240u_int utmp_len = HOST_NAME_MAX+1; 241 242/* options.max_startup sized array of fd ints */ 243int *startup_pipes = NULL; 244int startup_pipe; /* in child */ 245 246/* variables used for privilege separation */ 247int use_privsep = -1; 248struct monitor *pmonitor = NULL; 249int privsep_is_preauth = 1; 250static int privsep_chroot = 1; 251 252/* global authentication context */ 253Authctxt *the_authctxt = NULL; 254 255/* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 256struct sshauthopt *auth_opts = NULL; 257 258/* sshd_config buffer */ 259struct sshbuf *cfg; 260 261/* message to be displayed after login */ 262struct sshbuf *loginmsg; 263 264/* Unprivileged user */ 265struct passwd *privsep_pw = NULL; 266 267/* Prototypes for various functions defined later in this file. */ 268void destroy_sensitive_data(void); 269void demote_sensitive_data(void); 270static void do_ssh2_kex(void); 271 272/* 273 * Close all listening sockets 274 */ 275static void 276close_listen_socks(void) 277{ 278 int i; 279 280 for (i = 0; i < num_listen_socks; i++) 281 close(listen_socks[i]); 282 num_listen_socks = -1; 283} 284 285static void 286close_startup_pipes(void) 287{ 288 int i; 289 290 if (startup_pipes) 291 for (i = 0; i < options.max_startups; i++) 292 if (startup_pipes[i] != -1) 293 close(startup_pipes[i]); 294} 295 296/* 297 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 298 * the effect is to reread the configuration file (and to regenerate 299 * the server key). 300 */ 301 302/*ARGSUSED*/ 303static void 304sighup_handler(int sig) 305{ 306 int save_errno = errno; 307 308 received_sighup = 1; 309 errno = save_errno; 310} 311 312/* 313 * Called from the main program after receiving SIGHUP. 314 * Restarts the server. 315 */ 316static void 317sighup_restart(void) 318{ 319 logit("Received SIGHUP; restarting."); 320 if (options.pid_file != NULL) 321 unlink(options.pid_file); 322 platform_pre_restart(); 323 close_listen_socks(); 324 close_startup_pipes(); 325 alarm(0); /* alarm timer persists across exec */ 326 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 327 execv(saved_argv[0], saved_argv); 328 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 329 strerror(errno)); 330 exit(1); 331} 332 333/* 334 * Generic signal handler for terminating signals in the master daemon. 335 */ 336/*ARGSUSED*/ 337static void 338sigterm_handler(int sig) 339{ 340 received_sigterm = sig; 341} 342 343/* 344 * SIGCHLD handler. This is called whenever a child dies. This will then 345 * reap any zombies left by exited children. 346 */ 347/*ARGSUSED*/ 348static void 349main_sigchld_handler(int sig) 350{ 351 int save_errno = errno; 352 pid_t pid; 353 int status; 354 355 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 356 (pid < 0 && errno == EINTR)) 357 ; 358 errno = save_errno; 359} 360 361/* 362 * Signal handler for the alarm after the login grace period has expired. 363 */ 364/*ARGSUSED*/ 365static void 366grace_alarm_handler(int sig) 367{ 368 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 369 kill(pmonitor->m_pid, SIGALRM); 370 371 /* 372 * Try to kill any processes that we have spawned, E.g. authorized 373 * keys command helpers. 374 */ 375 if (getpgid(0) == getpid()) { 376 signal(SIGTERM, SIG_IGN); 377 kill(0, SIGTERM); 378 } 379 380 BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL, "ssh"); 381 382 /* Log error and exit. */ 383 sigdie("Timeout before authentication for %s port %d", 384 ssh_remote_ipaddr(active_state), ssh_remote_port(active_state)); 385} 386 387static void 388sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out) 389{ 390 u_int i; 391 int remote_major, remote_minor; 392 char *s; 393 char buf[256]; /* Must not be larger than remote_version. */ 394 char remote_version[256]; /* Must be at least as big as buf. */ 395 396 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s\r\n", 397 PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION, 398 *options.version_addendum == '\0' ? "" : " ", 399 options.version_addendum); 400 401 /* Send our protocol version identification. */ 402 if (atomicio(vwrite, sock_out, server_version_string, 403 strlen(server_version_string)) 404 != strlen(server_version_string)) { 405 logit("Could not write ident string to %s port %d", 406 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 407 cleanup_exit(255); 408 } 409 410 /* Read other sides version identification. */ 411 memset(buf, 0, sizeof(buf)); 412 for (i = 0; i < sizeof(buf) - 1; i++) { 413 if (atomicio(read, sock_in, &buf[i], 1) != 1) { 414 logit("Did not receive identification string " 415 "from %s port %d", 416 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 417 cleanup_exit(255); 418 } 419 if (buf[i] == '\r') { 420 buf[i] = 0; 421 /* Kludge for F-Secure Macintosh < 1.0.2 */ 422 if (i == 12 && 423 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 424 break; 425 continue; 426 } 427 if (buf[i] == '\n') { 428 buf[i] = 0; 429 break; 430 } 431 } 432 buf[sizeof(buf) - 1] = 0; 433 client_version_string = xstrdup(buf); 434 435 /* 436 * Check that the versions match. In future this might accept 437 * several versions and set appropriate flags to handle them. 438 */ 439 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 440 &remote_major, &remote_minor, remote_version) != 3) { 441 s = "Protocol mismatch.\n"; 442 (void) atomicio(vwrite, sock_out, s, strlen(s)); 443 logit("Bad protocol version identification '%.100s' " 444 "from %s port %d", client_version_string, 445 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 446 close(sock_in); 447 close(sock_out); 448 cleanup_exit(255); 449 } 450 debug("Client protocol version %d.%d; client software version %.100s", 451 remote_major, remote_minor, remote_version); 452 453 ssh->compat = compat_datafellows(remote_version); 454 455 if ((ssh->compat & SSH_BUG_PROBE) != 0) { 456 logit("probed from %s port %d with %s. Don't panic.", 457 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 458 client_version_string); 459 cleanup_exit(255); 460 } 461 if ((ssh->compat & SSH_BUG_SCANNER) != 0) { 462 logit("scanned from %s port %d with %s. Don't panic.", 463 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 464 client_version_string); 465 cleanup_exit(255); 466 } 467 if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) { 468 logit("Client version \"%.100s\" uses unsafe RSA signature " 469 "scheme; disabling use of RSA keys", remote_version); 470 } 471 472 chop(server_version_string); 473 debug("Local version string %.200s", server_version_string); 474 475 if (remote_major != 2 && 476 !(remote_major == 1 && remote_minor == 99)) { 477 s = "Protocol major versions differ.\n"; 478 (void) atomicio(vwrite, sock_out, s, strlen(s)); 479 close(sock_in); 480 close(sock_out); 481 logit("Protocol major versions differ for %s port %d: " 482 "%.200s vs. %.200s", 483 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 484 server_version_string, client_version_string); 485 cleanup_exit(255); 486 } 487} 488 489/* Destroy the host and server keys. They will no longer be needed. */ 490void 491destroy_sensitive_data(void) 492{ 493 u_int i; 494 495 for (i = 0; i < options.num_host_key_files; i++) { 496 if (sensitive_data.host_keys[i]) { 497 sshkey_free(sensitive_data.host_keys[i]); 498 sensitive_data.host_keys[i] = NULL; 499 } 500 if (sensitive_data.host_certificates[i]) { 501 sshkey_free(sensitive_data.host_certificates[i]); 502 sensitive_data.host_certificates[i] = NULL; 503 } 504 } 505} 506 507/* Demote private to public keys for network child */ 508void 509demote_sensitive_data(void) 510{ 511 struct sshkey *tmp; 512 u_int i; 513 int r; 514 515 for (i = 0; i < options.num_host_key_files; i++) { 516 if (sensitive_data.host_keys[i]) { 517 if ((r = sshkey_from_private( 518 sensitive_data.host_keys[i], &tmp)) != 0) 519 fatal("could not demote host %s key: %s", 520 sshkey_type(sensitive_data.host_keys[i]), 521 ssh_err(r)); 522 sshkey_free(sensitive_data.host_keys[i]); 523 sensitive_data.host_keys[i] = tmp; 524 } 525 /* Certs do not need demotion */ 526 } 527} 528 529static void 530reseed_prngs(void) 531{ 532 u_int32_t rnd[256]; 533 534#ifdef WITH_OPENSSL 535 RAND_poll(); 536#endif 537 arc4random_stir(); /* noop on recent arc4random() implementations */ 538 arc4random_buf(rnd, sizeof(rnd)); /* let arc4random notice PID change */ 539 540#ifdef WITH_OPENSSL 541 RAND_seed(rnd, sizeof(rnd)); 542 /* give libcrypto a chance to notice the PID change */ 543 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 544 fatal("%s: RAND_bytes failed", __func__); 545#endif 546 547 explicit_bzero(rnd, sizeof(rnd)); 548} 549 550static void 551privsep_preauth_child(void) 552{ 553 gid_t gidset[1]; 554 555 /* Enable challenge-response authentication for privilege separation */ 556 privsep_challenge_enable(); 557 558#ifdef GSSAPI 559 /* Cache supported mechanism OIDs for later use */ 560 ssh_gssapi_prepare_supported_oids(); 561#endif 562 563 reseed_prngs(); 564 565 /* Demote the private keys to public keys. */ 566 demote_sensitive_data(); 567 568 /* Demote the child */ 569 if (privsep_chroot) { 570 /* Change our root directory */ 571 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 572 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 573 strerror(errno)); 574 if (chdir("/") == -1) 575 fatal("chdir(\"/\"): %s", strerror(errno)); 576 577 /* Drop our privileges */ 578 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 579 (u_int)privsep_pw->pw_gid); 580 gidset[0] = privsep_pw->pw_gid; 581 if (setgroups(1, gidset) < 0) 582 fatal("setgroups: %.100s", strerror(errno)); 583 permanently_set_uid(privsep_pw); 584 } 585} 586 587static int 588privsep_preauth(Authctxt *authctxt) 589{ 590 int status, r; 591 pid_t pid; 592 struct ssh_sandbox *box = NULL; 593 594 /* Set up unprivileged child process to deal with network data */ 595 pmonitor = monitor_init(); 596 /* Store a pointer to the kex for later rekeying */ 597 pmonitor->m_pkex = &active_state->kex; 598 599 if (use_privsep == PRIVSEP_ON) 600 box = ssh_sandbox_init(pmonitor); 601 pid = fork(); 602 if (pid == -1) { 603 fatal("fork of unprivileged child failed"); 604 } else if (pid != 0) { 605 debug2("Network child is on pid %ld", (long)pid); 606 607 pmonitor->m_pid = pid; 608 if (have_agent) { 609 r = ssh_get_authentication_socket(&auth_sock); 610 if (r != 0) { 611 error("Could not get agent socket: %s", 612 ssh_err(r)); 613 have_agent = 0; 614 } 615 } 616 if (box != NULL) 617 ssh_sandbox_parent_preauth(box, pid); 618 monitor_child_preauth(authctxt, pmonitor); 619 620 /* Wait for the child's exit status */ 621 while (waitpid(pid, &status, 0) < 0) { 622 if (errno == EINTR) 623 continue; 624 pmonitor->m_pid = -1; 625 fatal("%s: waitpid: %s", __func__, strerror(errno)); 626 } 627 privsep_is_preauth = 0; 628 pmonitor->m_pid = -1; 629 if (WIFEXITED(status)) { 630 if (WEXITSTATUS(status) != 0) 631 fatal("%s: preauth child exited with status %d", 632 __func__, WEXITSTATUS(status)); 633 } else if (WIFSIGNALED(status)) 634 fatal("%s: preauth child terminated by signal %d", 635 __func__, WTERMSIG(status)); 636 if (box != NULL) 637 ssh_sandbox_parent_finish(box); 638 return 1; 639 } else { 640 /* child */ 641 close(pmonitor->m_sendfd); 642 close(pmonitor->m_log_recvfd); 643 644 /* Arrange for logging to be sent to the monitor */ 645 set_log_handler(mm_log_handler, pmonitor); 646 647 privsep_preauth_child(); 648 setproctitle("%s", "[net]"); 649 if (box != NULL) 650 ssh_sandbox_child(box); 651 652 return 0; 653 } 654} 655 656static void 657privsep_postauth(Authctxt *authctxt) 658{ 659#ifdef DISABLE_FD_PASSING 660 if (1) { 661#else 662 if (authctxt->pw->pw_uid == 0) { 663#endif 664 /* File descriptor passing is broken or root login */ 665 use_privsep = 0; 666 goto skip; 667 } 668 669 /* New socket pair */ 670 monitor_reinit(pmonitor); 671 672 pmonitor->m_pid = fork(); 673 if (pmonitor->m_pid == -1) 674 fatal("fork of unprivileged child failed"); 675 else if (pmonitor->m_pid != 0) { 676 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 677 sshbuf_reset(loginmsg); 678 monitor_clear_keystate(pmonitor); 679 monitor_child_postauth(pmonitor); 680 681 /* NEVERREACHED */ 682 exit(0); 683 } 684 685 /* child */ 686 687 close(pmonitor->m_sendfd); 688 pmonitor->m_sendfd = -1; 689 690 /* Demote the private keys to public keys. */ 691 demote_sensitive_data(); 692 693 reseed_prngs(); 694 695 /* Drop privileges */ 696 do_setusercontext(authctxt->pw); 697 698 skip: 699 /* It is safe now to apply the key state */ 700 monitor_apply_keystate(pmonitor); 701 702 /* 703 * Tell the packet layer that authentication was successful, since 704 * this information is not part of the key state. 705 */ 706 packet_set_authenticated(); 707} 708 709static void 710append_hostkey_type(struct sshbuf *b, const char *s) 711{ 712 int r; 713 714 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 715 debug3("%s: %s key not permitted by HostkeyAlgorithms", 716 __func__, s); 717 return; 718 } 719 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 720 fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r)); 721} 722 723static char * 724list_hostkey_types(void) 725{ 726 struct sshbuf *b; 727 struct sshkey *key; 728 char *ret; 729 u_int i; 730 731 if ((b = sshbuf_new()) == NULL) 732 fatal("%s: sshbuf_new failed", __func__); 733 for (i = 0; i < options.num_host_key_files; i++) { 734 key = sensitive_data.host_keys[i]; 735 if (key == NULL) 736 key = sensitive_data.host_pubkeys[i]; 737 if (key == NULL) 738 continue; 739 switch (key->type) { 740 case KEY_RSA: 741 /* for RSA we also support SHA2 signatures */ 742 append_hostkey_type(b, "rsa-sha2-512"); 743 append_hostkey_type(b, "rsa-sha2-256"); 744 /* FALLTHROUGH */ 745 case KEY_DSA: 746 case KEY_ECDSA: 747 case KEY_ED25519: 748 case KEY_XMSS: 749 append_hostkey_type(b, sshkey_ssh_name(key)); 750 break; 751 } 752 /* If the private key has a cert peer, then list that too */ 753 key = sensitive_data.host_certificates[i]; 754 if (key == NULL) 755 continue; 756 switch (key->type) { 757 case KEY_RSA_CERT: 758 /* for RSA we also support SHA2 signatures */ 759 append_hostkey_type(b, 760 "rsa-sha2-512-cert-v01@openssh.com"); 761 append_hostkey_type(b, 762 "rsa-sha2-256-cert-v01@openssh.com"); 763 /* FALLTHROUGH */ 764 case KEY_DSA_CERT: 765 case KEY_ECDSA_CERT: 766 case KEY_ED25519_CERT: 767 case KEY_XMSS_CERT: 768 append_hostkey_type(b, sshkey_ssh_name(key)); 769 break; 770 } 771 } 772 if ((ret = sshbuf_dup_string(b)) == NULL) 773 fatal("%s: sshbuf_dup_string failed", __func__); 774 sshbuf_free(b); 775 debug("%s: %s", __func__, ret); 776 return ret; 777} 778 779static struct sshkey * 780get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 781{ 782 u_int i; 783 struct sshkey *key; 784 785 for (i = 0; i < options.num_host_key_files; i++) { 786 switch (type) { 787 case KEY_RSA_CERT: 788 case KEY_DSA_CERT: 789 case KEY_ECDSA_CERT: 790 case KEY_ED25519_CERT: 791 case KEY_XMSS_CERT: 792 key = sensitive_data.host_certificates[i]; 793 break; 794 default: 795 key = sensitive_data.host_keys[i]; 796 if (key == NULL && !need_private) 797 key = sensitive_data.host_pubkeys[i]; 798 break; 799 } 800 if (key != NULL && key->type == type && 801 (key->type != KEY_ECDSA || key->ecdsa_nid == nid)) 802 return need_private ? 803 sensitive_data.host_keys[i] : key; 804 } 805 return NULL; 806} 807 808struct sshkey * 809get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 810{ 811 return get_hostkey_by_type(type, nid, 0, ssh); 812} 813 814struct sshkey * 815get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 816{ 817 return get_hostkey_by_type(type, nid, 1, ssh); 818} 819 820struct sshkey * 821get_hostkey_by_index(int ind) 822{ 823 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 824 return (NULL); 825 return (sensitive_data.host_keys[ind]); 826} 827 828struct sshkey * 829get_hostkey_public_by_index(int ind, struct ssh *ssh) 830{ 831 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 832 return (NULL); 833 return (sensitive_data.host_pubkeys[ind]); 834} 835 836int 837get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 838{ 839 u_int i; 840 841 for (i = 0; i < options.num_host_key_files; i++) { 842 if (sshkey_is_cert(key)) { 843 if (key == sensitive_data.host_certificates[i] || 844 (compare && sensitive_data.host_certificates[i] && 845 sshkey_equal(key, 846 sensitive_data.host_certificates[i]))) 847 return (i); 848 } else { 849 if (key == sensitive_data.host_keys[i] || 850 (compare && sensitive_data.host_keys[i] && 851 sshkey_equal(key, sensitive_data.host_keys[i]))) 852 return (i); 853 if (key == sensitive_data.host_pubkeys[i] || 854 (compare && sensitive_data.host_pubkeys[i] && 855 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 856 return (i); 857 } 858 } 859 return (-1); 860} 861 862/* Inform the client of all hostkeys */ 863static void 864notify_hostkeys(struct ssh *ssh) 865{ 866 struct sshbuf *buf; 867 struct sshkey *key; 868 u_int i, nkeys; 869 int r; 870 char *fp; 871 872 /* Some clients cannot cope with the hostkeys message, skip those. */ 873 if (datafellows & SSH_BUG_HOSTKEYS) 874 return; 875 876 if ((buf = sshbuf_new()) == NULL) 877 fatal("%s: sshbuf_new", __func__); 878 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 879 key = get_hostkey_public_by_index(i, ssh); 880 if (key == NULL || key->type == KEY_UNSPEC || 881 sshkey_is_cert(key)) 882 continue; 883 fp = sshkey_fingerprint(key, options.fingerprint_hash, 884 SSH_FP_DEFAULT); 885 debug3("%s: key %d: %s %s", __func__, i, 886 sshkey_ssh_name(key), fp); 887 free(fp); 888 if (nkeys == 0) { 889 packet_start(SSH2_MSG_GLOBAL_REQUEST); 890 packet_put_cstring("hostkeys-00@openssh.com"); 891 packet_put_char(0); /* want-reply */ 892 } 893 sshbuf_reset(buf); 894 if ((r = sshkey_putb(key, buf)) != 0) 895 fatal("%s: couldn't put hostkey %d: %s", 896 __func__, i, ssh_err(r)); 897 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf)); 898 nkeys++; 899 } 900 debug3("%s: sent %u hostkeys", __func__, nkeys); 901 if (nkeys == 0) 902 fatal("%s: no hostkeys", __func__); 903 packet_send(); 904 sshbuf_free(buf); 905} 906 907/* 908 * returns 1 if connection should be dropped, 0 otherwise. 909 * dropping starts at connection #max_startups_begin with a probability 910 * of (max_startups_rate/100). the probability increases linearly until 911 * all connections are dropped for startups > max_startups 912 */ 913static int 914drop_connection(int startups) 915{ 916 int p, r; 917 918 if (startups < options.max_startups_begin) 919 return 0; 920 if (startups >= options.max_startups) 921 return 1; 922 if (options.max_startups_rate == 100) 923 return 1; 924 925 p = 100 - options.max_startups_rate; 926 p *= startups - options.max_startups_begin; 927 p /= options.max_startups - options.max_startups_begin; 928 p += options.max_startups_rate; 929 r = arc4random_uniform(100); 930 931 debug("drop_connection: p %d, r %d", p, r); 932 return (r < p) ? 1 : 0; 933} 934 935static void 936usage(void) 937{ 938 if (options.version_addendum && *options.version_addendum != '\0') 939 fprintf(stderr, "%s %s, %s\n", 940 SSH_RELEASE, 941 options.version_addendum, OPENSSL_VERSION_STRING); 942 else 943 fprintf(stderr, "%s, %s\n", 944 SSH_RELEASE, OPENSSL_VERSION_STRING); 945 fprintf(stderr, 946"usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 947" [-E log_file] [-f config_file] [-g login_grace_time]\n" 948" [-h host_key_file] [-o option] [-p port] [-u len]\n" 949 ); 950 exit(1); 951} 952 953static void 954send_rexec_state(int fd, struct sshbuf *conf) 955{ 956 struct sshbuf *m; 957 int r; 958 959 debug3("%s: entering fd = %d config len %zu", __func__, fd, 960 sshbuf_len(conf)); 961 962 /* 963 * Protocol from reexec master to child: 964 * string configuration 965 * string rngseed (only if OpenSSL is not self-seeded) 966 */ 967 if ((m = sshbuf_new()) == NULL) 968 fatal("%s: sshbuf_new failed", __func__); 969 if ((r = sshbuf_put_stringb(m, conf)) != 0) 970 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 971 972#if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 973 rexec_send_rng_seed(m); 974#endif 975 976 if (ssh_msg_send(fd, 0, m) == -1) 977 fatal("%s: ssh_msg_send failed", __func__); 978 979 sshbuf_free(m); 980 981 debug3("%s: done", __func__); 982} 983 984static void 985recv_rexec_state(int fd, struct sshbuf *conf) 986{ 987 struct sshbuf *m; 988 u_char *cp, ver; 989 size_t len; 990 int r; 991 992 debug3("%s: entering fd = %d", __func__, fd); 993 994 if ((m = sshbuf_new()) == NULL) 995 fatal("%s: sshbuf_new failed", __func__); 996 if (ssh_msg_recv(fd, m) == -1) 997 fatal("%s: ssh_msg_recv failed", __func__); 998 if ((r = sshbuf_get_u8(m, &ver)) != 0) 999 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1000 if (ver != 0) 1001 fatal("%s: rexec version mismatch", __func__); 1002 if ((r = sshbuf_get_string(m, &cp, &len)) != 0) 1003 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1004 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 1005 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1006#if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 1007 rexec_recv_rng_seed(m); 1008#endif 1009 1010 free(cp); 1011 sshbuf_free(m); 1012 1013 debug3("%s: done", __func__); 1014} 1015 1016/* Accept a connection from inetd */ 1017static void 1018server_accept_inetd(int *sock_in, int *sock_out) 1019{ 1020 int fd; 1021 1022 startup_pipe = -1; 1023 if (rexeced_flag) { 1024 close(REEXEC_CONFIG_PASS_FD); 1025 *sock_in = *sock_out = dup(STDIN_FILENO); 1026 if (!debug_flag) { 1027 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1028 close(REEXEC_STARTUP_PIPE_FD); 1029 } 1030 } else { 1031 *sock_in = dup(STDIN_FILENO); 1032 *sock_out = dup(STDOUT_FILENO); 1033 } 1034 /* 1035 * We intentionally do not close the descriptors 0, 1, and 2 1036 * as our code for setting the descriptors won't work if 1037 * ttyfd happens to be one of those. 1038 */ 1039 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1040 dup2(fd, STDIN_FILENO); 1041 dup2(fd, STDOUT_FILENO); 1042 if (!log_stderr) 1043 dup2(fd, STDERR_FILENO); 1044 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1045 close(fd); 1046 } 1047 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1048} 1049 1050/* 1051 * Listen for TCP connections 1052 */ 1053static void 1054listen_on_addrs(struct listenaddr *la) 1055{ 1056 int ret, listen_sock; 1057 struct addrinfo *ai; 1058 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1059 1060 for (ai = la->addrs; ai; ai = ai->ai_next) { 1061 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1062 continue; 1063 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1064 fatal("Too many listen sockets. " 1065 "Enlarge MAX_LISTEN_SOCKS"); 1066 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1067 ntop, sizeof(ntop), strport, sizeof(strport), 1068 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1069 error("getnameinfo failed: %.100s", 1070 ssh_gai_strerror(ret)); 1071 continue; 1072 } 1073 /* Create socket for listening. */ 1074 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1075 ai->ai_protocol); 1076 if (listen_sock < 0) { 1077 /* kernel may not support ipv6 */ 1078 verbose("socket: %.100s", strerror(errno)); 1079 continue; 1080 } 1081 if (set_nonblock(listen_sock) == -1) { 1082 close(listen_sock); 1083 continue; 1084 } 1085 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1086 verbose("socket: CLOEXEC: %s", strerror(errno)); 1087 close(listen_sock); 1088 continue; 1089 } 1090 /* Socket options */ 1091 set_reuseaddr(listen_sock); 1092 if (la->rdomain != NULL && 1093 set_rdomain(listen_sock, la->rdomain) == -1) { 1094 close(listen_sock); 1095 continue; 1096 } 1097 1098 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1099 if (ai->ai_family == AF_INET6) 1100 sock_set_v6only(listen_sock); 1101 1102 debug("Bind to port %s on %s.", strport, ntop); 1103 1104 /* Bind the socket to the desired port. */ 1105 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1106 error("Bind to port %s on %s failed: %.200s.", 1107 strport, ntop, strerror(errno)); 1108 close(listen_sock); 1109 continue; 1110 } 1111 listen_socks[num_listen_socks] = listen_sock; 1112 num_listen_socks++; 1113 1114 /* Start listening on the port. */ 1115 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1116 fatal("listen on [%s]:%s: %.100s", 1117 ntop, strport, strerror(errno)); 1118 logit("Server listening on %s port %s%s%s.", 1119 ntop, strport, 1120 la->rdomain == NULL ? "" : " rdomain ", 1121 la->rdomain == NULL ? "" : la->rdomain); 1122 } 1123} 1124 1125static void 1126server_listen(void) 1127{ 1128 u_int i; 1129 1130 for (i = 0; i < options.num_listen_addrs; i++) { 1131 listen_on_addrs(&options.listen_addrs[i]); 1132 freeaddrinfo(options.listen_addrs[i].addrs); 1133 free(options.listen_addrs[i].rdomain); 1134 memset(&options.listen_addrs[i], 0, 1135 sizeof(options.listen_addrs[i])); 1136 } 1137 free(options.listen_addrs); 1138 options.listen_addrs = NULL; 1139 options.num_listen_addrs = 0; 1140 1141 if (!num_listen_socks) 1142 fatal("Cannot bind any address."); 1143} 1144 1145/* 1146 * The main TCP accept loop. Note that, for the non-debug case, returns 1147 * from this function are in a forked subprocess. 1148 */ 1149static void 1150server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1151{ 1152 fd_set *fdset; 1153 int i, j, ret, maxfd; 1154 int startups = 0; 1155 int startup_p[2] = { -1 , -1 }; 1156 struct sockaddr_storage from; 1157 socklen_t fromlen; 1158 pid_t pid; 1159 u_char rnd[256]; 1160 1161 /* setup fd set for accept */ 1162 fdset = NULL; 1163 maxfd = 0; 1164 for (i = 0; i < num_listen_socks; i++) 1165 if (listen_socks[i] > maxfd) 1166 maxfd = listen_socks[i]; 1167 /* pipes connected to unauthenticated childs */ 1168 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1169 for (i = 0; i < options.max_startups; i++) 1170 startup_pipes[i] = -1; 1171 1172 /* 1173 * Stay listening for connections until the system crashes or 1174 * the daemon is killed with a signal. 1175 */ 1176 for (;;) { 1177 if (received_sighup) 1178 sighup_restart(); 1179 free(fdset); 1180 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1181 sizeof(fd_mask)); 1182 1183 for (i = 0; i < num_listen_socks; i++) 1184 FD_SET(listen_socks[i], fdset); 1185 for (i = 0; i < options.max_startups; i++) 1186 if (startup_pipes[i] != -1) 1187 FD_SET(startup_pipes[i], fdset); 1188 1189 /* Wait in select until there is a connection. */ 1190 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1191 if (ret < 0 && errno != EINTR) 1192 error("select: %.100s", strerror(errno)); 1193 if (received_sigterm) { 1194 logit("Received signal %d; terminating.", 1195 (int) received_sigterm); 1196 close_listen_socks(); 1197 if (options.pid_file != NULL) 1198 unlink(options.pid_file); 1199 exit(received_sigterm == SIGTERM ? 0 : 255); 1200 } 1201 if (ret < 0) 1202 continue; 1203 1204 for (i = 0; i < options.max_startups; i++) 1205 if (startup_pipes[i] != -1 && 1206 FD_ISSET(startup_pipes[i], fdset)) { 1207 /* 1208 * the read end of the pipe is ready 1209 * if the child has closed the pipe 1210 * after successful authentication 1211 * or if the child has died 1212 */ 1213 close(startup_pipes[i]); 1214 startup_pipes[i] = -1; 1215 startups--; 1216 } 1217 for (i = 0; i < num_listen_socks; i++) { 1218 if (!FD_ISSET(listen_socks[i], fdset)) 1219 continue; 1220 fromlen = sizeof(from); 1221 *newsock = accept(listen_socks[i], 1222 (struct sockaddr *)&from, &fromlen); 1223 if (*newsock < 0) { 1224 if (errno != EINTR && errno != EWOULDBLOCK && 1225 errno != ECONNABORTED && errno != EAGAIN) 1226 error("accept: %.100s", 1227 strerror(errno)); 1228 if (errno == EMFILE || errno == ENFILE) 1229 usleep(100 * 1000); 1230 continue; 1231 } 1232 if (unset_nonblock(*newsock) == -1) { 1233 close(*newsock); 1234 continue; 1235 } 1236 if (drop_connection(startups) == 1) { 1237 char *laddr = get_local_ipaddr(*newsock); 1238 char *raddr = get_peer_ipaddr(*newsock); 1239 1240 verbose("drop connection #%d from [%s]:%d " 1241 "on [%s]:%d past MaxStartups", startups, 1242 raddr, get_peer_port(*newsock), 1243 laddr, get_local_port(*newsock)); 1244 free(laddr); 1245 free(raddr); 1246 close(*newsock); 1247 continue; 1248 } 1249 if (pipe(startup_p) == -1) { 1250 close(*newsock); 1251 continue; 1252 } 1253 1254 if (rexec_flag && socketpair(AF_UNIX, 1255 SOCK_STREAM, 0, config_s) == -1) { 1256 error("reexec socketpair: %s", 1257 strerror(errno)); 1258 close(*newsock); 1259 close(startup_p[0]); 1260 close(startup_p[1]); 1261 continue; 1262 } 1263 1264 for (j = 0; j < options.max_startups; j++) 1265 if (startup_pipes[j] == -1) { 1266 startup_pipes[j] = startup_p[0]; 1267 if (maxfd < startup_p[0]) 1268 maxfd = startup_p[0]; 1269 startups++; 1270 break; 1271 } 1272 1273 /* 1274 * Got connection. Fork a child to handle it, unless 1275 * we are in debugging mode. 1276 */ 1277 if (debug_flag) { 1278 /* 1279 * In debugging mode. Close the listening 1280 * socket, and start processing the 1281 * connection without forking. 1282 */ 1283 debug("Server will not fork when running in debugging mode."); 1284 close_listen_socks(); 1285 *sock_in = *newsock; 1286 *sock_out = *newsock; 1287 close(startup_p[0]); 1288 close(startup_p[1]); 1289 startup_pipe = -1; 1290 pid = getpid(); 1291 if (rexec_flag) { 1292 send_rexec_state(config_s[0], cfg); 1293 close(config_s[0]); 1294 } 1295 break; 1296 } 1297 1298 /* 1299 * Normal production daemon. Fork, and have 1300 * the child process the connection. The 1301 * parent continues listening. 1302 */ 1303 platform_pre_fork(); 1304 if ((pid = fork()) == 0) { 1305 /* 1306 * Child. Close the listening and 1307 * max_startup sockets. Start using 1308 * the accepted socket. Reinitialize 1309 * logging (since our pid has changed). 1310 * We break out of the loop to handle 1311 * the connection. 1312 */ 1313 platform_post_fork_child(); 1314 startup_pipe = startup_p[1]; 1315 close_startup_pipes(); 1316 close_listen_socks(); 1317 *sock_in = *newsock; 1318 *sock_out = *newsock; 1319 log_init(__progname, 1320 options.log_level, 1321 options.log_facility, 1322 log_stderr); 1323 if (rexec_flag) 1324 close(config_s[0]); 1325 break; 1326 } 1327 1328 /* Parent. Stay in the loop. */ 1329 platform_post_fork_parent(pid); 1330 if (pid < 0) 1331 error("fork: %.100s", strerror(errno)); 1332 else 1333 debug("Forked child %ld.", (long)pid); 1334 1335 close(startup_p[1]); 1336 1337 if (rexec_flag) { 1338 send_rexec_state(config_s[0], cfg); 1339 close(config_s[0]); 1340 close(config_s[1]); 1341 } 1342 close(*newsock); 1343 1344 /* 1345 * Ensure that our random state differs 1346 * from that of the child 1347 */ 1348 arc4random_stir(); 1349 arc4random_buf(rnd, sizeof(rnd)); 1350#ifdef WITH_OPENSSL 1351 RAND_seed(rnd, sizeof(rnd)); 1352 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 1353 fatal("%s: RAND_bytes failed", __func__); 1354#endif 1355 explicit_bzero(rnd, sizeof(rnd)); 1356 } 1357 1358 /* child process check (or debug mode) */ 1359 if (num_listen_socks < 0) 1360 break; 1361 } 1362} 1363 1364/* 1365 * If IP options are supported, make sure there are none (log and 1366 * return an error if any are found). Basically we are worried about 1367 * source routing; it can be used to pretend you are somebody 1368 * (ip-address) you are not. That itself may be "almost acceptable" 1369 * under certain circumstances, but rhosts authentication is useless 1370 * if source routing is accepted. Notice also that if we just dropped 1371 * source routing here, the other side could use IP spoofing to do 1372 * rest of the interaction and could still bypass security. So we 1373 * exit here if we detect any IP options. 1374 */ 1375static void 1376check_ip_options(struct ssh *ssh) 1377{ 1378#ifdef IP_OPTIONS 1379 int sock_in = ssh_packet_get_connection_in(ssh); 1380 struct sockaddr_storage from; 1381 u_char opts[200]; 1382 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1383 char text[sizeof(opts) * 3 + 1]; 1384 1385 memset(&from, 0, sizeof(from)); 1386 if (getpeername(sock_in, (struct sockaddr *)&from, 1387 &fromlen) < 0) 1388 return; 1389 if (from.ss_family != AF_INET) 1390 return; 1391 /* XXX IPv6 options? */ 1392 1393 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1394 &option_size) >= 0 && option_size != 0) { 1395 text[0] = '\0'; 1396 for (i = 0; i < option_size; i++) 1397 snprintf(text + i*3, sizeof(text) - i*3, 1398 " %2.2x", opts[i]); 1399 fatal("Connection from %.100s port %d with IP opts: %.800s", 1400 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1401 } 1402 return; 1403#endif /* IP_OPTIONS */ 1404} 1405 1406/* Set the routing domain for this process */ 1407static void 1408set_process_rdomain(struct ssh *ssh, const char *name) 1409{ 1410#if defined(HAVE_SYS_SET_PROCESS_RDOMAIN) 1411 if (name == NULL) 1412 return; /* default */ 1413 1414 if (strcmp(name, "%D") == 0) { 1415 /* "expands" to routing domain of connection */ 1416 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1417 return; 1418 } 1419 /* NB. We don't pass 'ssh' to sys_set_process_rdomain() */ 1420 return sys_set_process_rdomain(name); 1421#elif defined(__OpenBSD__) 1422 int rtable, ortable = getrtable(); 1423 const char *errstr; 1424 1425 if (name == NULL) 1426 return; /* default */ 1427 1428 if (strcmp(name, "%D") == 0) { 1429 /* "expands" to routing domain of connection */ 1430 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1431 return; 1432 } 1433 1434 rtable = (int)strtonum(name, 0, 255, &errstr); 1435 if (errstr != NULL) /* Shouldn't happen */ 1436 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1437 if (rtable != ortable && setrtable(rtable) != 0) 1438 fatal("Unable to set routing domain %d: %s", 1439 rtable, strerror(errno)); 1440 debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable); 1441#else /* defined(__OpenBSD__) */ 1442 fatal("Unable to set routing domain: not supported in this platform"); 1443#endif 1444} 1445 1446static void 1447accumulate_host_timing_secret(struct sshbuf *server_cfg, 1448 const struct sshkey *key) 1449{ 1450 static struct ssh_digest_ctx *ctx; 1451 u_char *hash; 1452 size_t len; 1453 struct sshbuf *buf; 1454 int r; 1455 1456 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1457 fatal("%s: ssh_digest_start", __func__); 1458 if (key == NULL) { /* finalize */ 1459 /* add server config in case we are using agent for host keys */ 1460 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1461 sshbuf_len(server_cfg)) != 0) 1462 fatal("%s: ssh_digest_update", __func__); 1463 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1464 hash = xmalloc(len); 1465 if (ssh_digest_final(ctx, hash, len) != 0) 1466 fatal("%s: ssh_digest_final", __func__); 1467 options.timing_secret = PEEK_U64(hash); 1468 freezero(hash, len); 1469 ssh_digest_free(ctx); 1470 ctx = NULL; 1471 return; 1472 } 1473 if ((buf = sshbuf_new()) == NULL) 1474 fatal("%s could not allocate buffer", __func__); 1475 if ((r = sshkey_private_serialize(key, buf)) != 0) 1476 fatal("sshkey_private_serialize: %s", ssh_err(r)); 1477 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1478 fatal("%s: ssh_digest_update", __func__); 1479 sshbuf_reset(buf); 1480 sshbuf_free(buf); 1481} 1482 1483/* 1484 * Main program for the daemon. 1485 */ 1486int 1487main(int ac, char **av) 1488{ 1489 struct ssh *ssh = NULL; 1490 extern char *optarg; 1491 extern int optind; 1492 int r, opt, on = 1, already_daemon, remote_port; 1493 int sock_in = -1, sock_out = -1, newsock = -1; 1494 const char *remote_ip, *rdomain; 1495 char *fp, *line, *laddr, *logfile = NULL; 1496 int config_s[2] = { -1 , -1 }; 1497 u_int i, j; 1498 u_int64_t ibytes, obytes; 1499 mode_t new_umask; 1500 struct sshkey *key; 1501 struct sshkey *pubkey; 1502 int keytype; 1503 Authctxt *authctxt; 1504 struct connection_info *connection_info = NULL; 1505 1506 ssh_malloc_init(); /* must be called before any mallocs */ 1507 1508#ifdef HAVE_SECUREWARE 1509 (void)set_auth_parameters(ac, av); 1510#endif 1511 __progname = ssh_get_progname(av[0]); 1512 1513 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1514 saved_argc = ac; 1515 rexec_argc = ac; 1516 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1517 for (i = 0; (int)i < ac; i++) 1518 saved_argv[i] = xstrdup(av[i]); 1519 saved_argv[i] = NULL; 1520 1521#ifndef HAVE_SETPROCTITLE 1522 /* Prepare for later setproctitle emulation */ 1523 compat_init_setproctitle(ac, av); 1524 av = saved_argv; 1525#endif 1526 1527 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1528 debug("setgroups(): %.200s", strerror(errno)); 1529 1530 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1531 sanitise_stdfd(); 1532 1533 /* Initialize configuration options to their default values. */ 1534 initialize_server_options(&options); 1535 1536 /* Parse command-line arguments. */ 1537 while ((opt = getopt(ac, av, 1538 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1539 switch (opt) { 1540 case '4': 1541 options.address_family = AF_INET; 1542 break; 1543 case '6': 1544 options.address_family = AF_INET6; 1545 break; 1546 case 'f': 1547 config_file_name = optarg; 1548 break; 1549 case 'c': 1550 servconf_add_hostcert("[command-line]", 0, 1551 &options, optarg); 1552 break; 1553 case 'd': 1554 if (debug_flag == 0) { 1555 debug_flag = 1; 1556 options.log_level = SYSLOG_LEVEL_DEBUG1; 1557 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1558 options.log_level++; 1559 break; 1560 case 'D': 1561 no_daemon_flag = 1; 1562 break; 1563 case 'E': 1564 logfile = optarg; 1565 /* FALLTHROUGH */ 1566 case 'e': 1567 log_stderr = 1; 1568 break; 1569 case 'i': 1570 inetd_flag = 1; 1571 break; 1572 case 'r': 1573 rexec_flag = 0; 1574 break; 1575 case 'R': 1576 rexeced_flag = 1; 1577 inetd_flag = 1; 1578 break; 1579 case 'Q': 1580 /* ignored */ 1581 break; 1582 case 'q': 1583 options.log_level = SYSLOG_LEVEL_QUIET; 1584 break; 1585 case 'b': 1586 /* protocol 1, ignored */ 1587 break; 1588 case 'p': 1589 options.ports_from_cmdline = 1; 1590 if (options.num_ports >= MAX_PORTS) { 1591 fprintf(stderr, "too many ports.\n"); 1592 exit(1); 1593 } 1594 options.ports[options.num_ports++] = a2port(optarg); 1595 if (options.ports[options.num_ports-1] <= 0) { 1596 fprintf(stderr, "Bad port number.\n"); 1597 exit(1); 1598 } 1599 break; 1600 case 'g': 1601 if ((options.login_grace_time = convtime(optarg)) == -1) { 1602 fprintf(stderr, "Invalid login grace time.\n"); 1603 exit(1); 1604 } 1605 break; 1606 case 'k': 1607 /* protocol 1, ignored */ 1608 break; 1609 case 'h': 1610 servconf_add_hostkey("[command-line]", 0, 1611 &options, optarg); 1612 break; 1613 case 't': 1614 test_flag = 1; 1615 break; 1616 case 'T': 1617 test_flag = 2; 1618 break; 1619 case 'C': 1620 connection_info = get_connection_info(0, 0); 1621 if (parse_server_match_testspec(connection_info, 1622 optarg) == -1) 1623 exit(1); 1624 break; 1625 case 'u': 1626 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1627 if (utmp_len > HOST_NAME_MAX+1) { 1628 fprintf(stderr, "Invalid utmp length.\n"); 1629 exit(1); 1630 } 1631 break; 1632 case 'o': 1633 line = xstrdup(optarg); 1634 if (process_server_config_line(&options, line, 1635 "command-line", 0, NULL, NULL) != 0) 1636 exit(1); 1637 free(line); 1638 break; 1639 case '?': 1640 default: 1641 usage(); 1642 break; 1643 } 1644 } 1645 if (rexeced_flag || inetd_flag) 1646 rexec_flag = 0; 1647 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1648 fatal("sshd re-exec requires execution with an absolute path"); 1649 if (rexeced_flag) 1650 closefrom(REEXEC_MIN_FREE_FD); 1651 else 1652 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1653 1654#ifdef WITH_OPENSSL 1655 OpenSSL_add_all_algorithms(); 1656#endif 1657 1658 /* If requested, redirect the logs to the specified logfile. */ 1659 if (logfile != NULL) 1660 log_redirect_stderr_to(logfile); 1661 /* 1662 * Force logging to stderr until we have loaded the private host 1663 * key (unless started from inetd) 1664 */ 1665 log_init(__progname, 1666 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1667 SYSLOG_LEVEL_INFO : options.log_level, 1668 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1669 SYSLOG_FACILITY_AUTH : options.log_facility, 1670 log_stderr || !inetd_flag); 1671 1672 /* 1673 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1674 * root's environment 1675 */ 1676 if (getenv("KRB5CCNAME") != NULL) 1677 (void) unsetenv("KRB5CCNAME"); 1678 1679 sensitive_data.have_ssh2_key = 0; 1680 1681 /* 1682 * If we're not doing an extended test do not silently ignore connection 1683 * test params. 1684 */ 1685 if (test_flag < 2 && connection_info != NULL) 1686 fatal("Config test connection parameter (-C) provided without " 1687 "test mode (-T)"); 1688 1689 /* Fetch our configuration */ 1690 if ((cfg = sshbuf_new()) == NULL) 1691 fatal("%s: sshbuf_new failed", __func__); 1692 if (rexeced_flag) 1693 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1694 else if (strcasecmp(config_file_name, "none") != 0) 1695 load_server_config(config_file_name, cfg); 1696 1697 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1698 cfg, NULL); 1699 1700 seed_rng(); 1701 1702 /* Fill in default values for those options not explicitly set. */ 1703 fill_default_server_options(&options); 1704 1705 /* challenge-response is implemented via keyboard interactive */ 1706 if (options.challenge_response_authentication) 1707 options.kbd_interactive_authentication = 1; 1708 1709 /* Check that options are sensible */ 1710 if (options.authorized_keys_command_user == NULL && 1711 (options.authorized_keys_command != NULL && 1712 strcasecmp(options.authorized_keys_command, "none") != 0)) 1713 fatal("AuthorizedKeysCommand set without " 1714 "AuthorizedKeysCommandUser"); 1715 if (options.authorized_principals_command_user == NULL && 1716 (options.authorized_principals_command != NULL && 1717 strcasecmp(options.authorized_principals_command, "none") != 0)) 1718 fatal("AuthorizedPrincipalsCommand set without " 1719 "AuthorizedPrincipalsCommandUser"); 1720 1721 /* 1722 * Check whether there is any path through configured auth methods. 1723 * Unfortunately it is not possible to verify this generally before 1724 * daemonisation in the presence of Match block, but this catches 1725 * and warns for trivial misconfigurations that could break login. 1726 */ 1727 if (options.num_auth_methods != 0) { 1728 for (i = 0; i < options.num_auth_methods; i++) { 1729 if (auth2_methods_valid(options.auth_methods[i], 1730 1) == 0) 1731 break; 1732 } 1733 if (i >= options.num_auth_methods) 1734 fatal("AuthenticationMethods cannot be satisfied by " 1735 "enabled authentication methods"); 1736 } 1737 1738 /* Check that there are no remaining arguments. */ 1739 if (optind < ac) { 1740 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1741 exit(1); 1742 } 1743 1744 debug("sshd version %s, %s", SSH_VERSION, 1745#ifdef WITH_OPENSSL 1746 OpenSSL_version(OPENSSL_VERSION) 1747#else 1748 "without OpenSSL" 1749#endif 1750 ); 1751 1752 /* Store privilege separation user for later use if required. */ 1753 privsep_chroot = use_privsep && (getuid() == 0 || geteuid() == 0); 1754 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1755 if (privsep_chroot || options.kerberos_authentication) 1756 fatal("Privilege separation user %s does not exist", 1757 SSH_PRIVSEP_USER); 1758 } else { 1759 privsep_pw = pwcopy(privsep_pw); 1760 freezero(privsep_pw->pw_passwd, strlen(privsep_pw->pw_passwd)); 1761 privsep_pw->pw_passwd = xstrdup("*"); 1762 } 1763 endpwent(); 1764 1765 /* load host keys */ 1766 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1767 sizeof(struct sshkey *)); 1768 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1769 sizeof(struct sshkey *)); 1770 1771 if (options.host_key_agent) { 1772 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1773 setenv(SSH_AUTHSOCKET_ENV_NAME, 1774 options.host_key_agent, 1); 1775 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1776 have_agent = 1; 1777 else 1778 error("Could not connect to agent \"%s\": %s", 1779 options.host_key_agent, ssh_err(r)); 1780 } 1781 1782 for (i = 0; i < options.num_host_key_files; i++) { 1783 if (options.host_key_files[i] == NULL) 1784 continue; 1785 if ((r = sshkey_load_private(options.host_key_files[i], "", 1786 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1787 error("Error loading host key \"%s\": %s", 1788 options.host_key_files[i], ssh_err(r)); 1789 if ((r = sshkey_load_public(options.host_key_files[i], 1790 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1791 error("Error loading host key \"%s\": %s", 1792 options.host_key_files[i], ssh_err(r)); 1793 if (pubkey == NULL && key != NULL) 1794 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1795 fatal("Could not demote key: \"%s\": %s", 1796 options.host_key_files[i], ssh_err(r)); 1797 sensitive_data.host_keys[i] = key; 1798 sensitive_data.host_pubkeys[i] = pubkey; 1799 1800 if (key == NULL && pubkey != NULL && have_agent) { 1801 debug("will rely on agent for hostkey %s", 1802 options.host_key_files[i]); 1803 keytype = pubkey->type; 1804 } else if (key != NULL) { 1805 keytype = key->type; 1806 accumulate_host_timing_secret(cfg, key); 1807 } else { 1808 error("Could not load host key: %s", 1809 options.host_key_files[i]); 1810 sensitive_data.host_keys[i] = NULL; 1811 sensitive_data.host_pubkeys[i] = NULL; 1812 continue; 1813 } 1814 1815 switch (keytype) { 1816 case KEY_RSA: 1817 case KEY_DSA: 1818 case KEY_ECDSA: 1819 case KEY_ED25519: 1820 case KEY_XMSS: 1821 if (have_agent || key != NULL) 1822 sensitive_data.have_ssh2_key = 1; 1823 break; 1824 } 1825 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1826 SSH_FP_DEFAULT)) == NULL) 1827 fatal("sshkey_fingerprint failed"); 1828 debug("%s host key #%d: %s %s", 1829 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1830 free(fp); 1831 } 1832 accumulate_host_timing_secret(cfg, NULL); 1833 if (!sensitive_data.have_ssh2_key) { 1834 logit("sshd: no hostkeys available -- exiting."); 1835 exit(1); 1836 } 1837 1838 /* 1839 * Load certificates. They are stored in an array at identical 1840 * indices to the public keys that they relate to. 1841 */ 1842 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1843 sizeof(struct sshkey *)); 1844 for (i = 0; i < options.num_host_key_files; i++) 1845 sensitive_data.host_certificates[i] = NULL; 1846 1847 for (i = 0; i < options.num_host_cert_files; i++) { 1848 if (options.host_cert_files[i] == NULL) 1849 continue; 1850 if ((r = sshkey_load_public(options.host_cert_files[i], 1851 &key, NULL)) != 0) { 1852 error("Could not load host certificate \"%s\": %s", 1853 options.host_cert_files[i], ssh_err(r)); 1854 continue; 1855 } 1856 if (!sshkey_is_cert(key)) { 1857 error("Certificate file is not a certificate: %s", 1858 options.host_cert_files[i]); 1859 sshkey_free(key); 1860 continue; 1861 } 1862 /* Find matching private key */ 1863 for (j = 0; j < options.num_host_key_files; j++) { 1864 if (sshkey_equal_public(key, 1865 sensitive_data.host_keys[j])) { 1866 sensitive_data.host_certificates[j] = key; 1867 break; 1868 } 1869 } 1870 if (j >= options.num_host_key_files) { 1871 error("No matching private key for certificate: %s", 1872 options.host_cert_files[i]); 1873 sshkey_free(key); 1874 continue; 1875 } 1876 sensitive_data.host_certificates[j] = key; 1877 debug("host certificate: #%u type %d %s", j, key->type, 1878 sshkey_type(key)); 1879 } 1880 1881 if (privsep_chroot) { 1882 struct stat st; 1883 1884 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1885 (S_ISDIR(st.st_mode) == 0)) 1886 fatal("Missing privilege separation directory: %s", 1887 _PATH_PRIVSEP_CHROOT_DIR); 1888 1889#ifdef HAVE_CYGWIN 1890 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1891 (st.st_uid != getuid () || 1892 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1893#else 1894 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1895#endif 1896 fatal("%s must be owned by root and not group or " 1897 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1898 } 1899 1900 if (test_flag > 1) { 1901 /* 1902 * If no connection info was provided by -C then use 1903 * use a blank one that will cause no predicate to match. 1904 */ 1905 if (connection_info == NULL) 1906 connection_info = get_connection_info(0, 0); 1907 parse_server_match_config(&options, connection_info); 1908 dump_config(&options); 1909 } 1910 1911 /* Configuration looks good, so exit if in test mode. */ 1912 if (test_flag) 1913 exit(0); 1914 1915 /* 1916 * Clear out any supplemental groups we may have inherited. This 1917 * prevents inadvertent creation of files with bad modes (in the 1918 * portable version at least, it's certainly possible for PAM 1919 * to create a file, and we can't control the code in every 1920 * module which might be used). 1921 */ 1922 if (setgroups(0, NULL) < 0) 1923 debug("setgroups() failed: %.200s", strerror(errno)); 1924 1925 if (rexec_flag) { 1926 if (rexec_argc < 0) 1927 fatal("rexec_argc %d < 0", rexec_argc); 1928 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1929 for (i = 0; i < (u_int)rexec_argc; i++) { 1930 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1931 rexec_argv[i] = saved_argv[i]; 1932 } 1933 rexec_argv[rexec_argc] = "-R"; 1934 rexec_argv[rexec_argc + 1] = NULL; 1935 } 1936 1937 /* Ensure that umask disallows at least group and world write */ 1938 new_umask = umask(0077) | 0022; 1939 (void) umask(new_umask); 1940 1941 /* Initialize the log (it is reinitialized below in case we forked). */ 1942 if (debug_flag && (!inetd_flag || rexeced_flag)) 1943 log_stderr = 1; 1944 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1945 1946 /* 1947 * If not in debugging mode, not started from inetd and not already 1948 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1949 * terminal, and fork. The original process exits. 1950 */ 1951 already_daemon = daemonized(); 1952 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1953 1954 if (daemon(0, 0) < 0) 1955 fatal("daemon() failed: %.200s", strerror(errno)); 1956 1957 disconnect_controlling_tty(); 1958 } 1959 /* Reinitialize the log (because of the fork above). */ 1960 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1961 1962 /* Avoid killing the process in high-pressure swapping environments. */ 1963 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 1964 debug("madvise(): %.200s", strerror(errno)); 1965 1966 /* Chdir to the root directory so that the current disk can be 1967 unmounted if desired. */ 1968 if (chdir("/") == -1) 1969 error("chdir(\"/\"): %s", strerror(errno)); 1970 1971 /* ignore SIGPIPE */ 1972 signal(SIGPIPE, SIG_IGN); 1973 1974 /* Get a connection, either from inetd or a listening TCP socket */ 1975 if (inetd_flag) { 1976 server_accept_inetd(&sock_in, &sock_out); 1977 } else { 1978 platform_pre_listen(); 1979 server_listen(); 1980 1981 signal(SIGHUP, sighup_handler); 1982 signal(SIGCHLD, main_sigchld_handler); 1983 signal(SIGTERM, sigterm_handler); 1984 signal(SIGQUIT, sigterm_handler); 1985 1986 /* 1987 * Write out the pid file after the sigterm handler 1988 * is setup and the listen sockets are bound 1989 */ 1990 if (options.pid_file != NULL && !debug_flag) { 1991 FILE *f = fopen(options.pid_file, "w"); 1992 1993 if (f == NULL) { 1994 error("Couldn't create pid file \"%s\": %s", 1995 options.pid_file, strerror(errno)); 1996 } else { 1997 fprintf(f, "%ld\n", (long) getpid()); 1998 fclose(f); 1999 } 2000 } 2001 2002 /* Accept a connection and return in a forked child */ 2003 server_accept_loop(&sock_in, &sock_out, 2004 &newsock, config_s); 2005 } 2006 2007 /* This is the child processing a new connection. */ 2008 setproctitle("%s", "[accepted]"); 2009 2010 /* 2011 * Create a new session and process group since the 4.4BSD 2012 * setlogin() affects the entire process group. We don't 2013 * want the child to be able to affect the parent. 2014 */ 2015#if !defined(SSHD_ACQUIRES_CTTY) 2016 /* 2017 * If setsid is called, on some platforms sshd will later acquire a 2018 * controlling terminal which will result in "could not set 2019 * controlling tty" errors. 2020 */ 2021 if (!debug_flag && !inetd_flag && setsid() < 0) 2022 error("setsid: %.100s", strerror(errno)); 2023#endif 2024 2025 if (rexec_flag) { 2026 int fd; 2027 2028 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 2029 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2030 dup2(newsock, STDIN_FILENO); 2031 dup2(STDIN_FILENO, STDOUT_FILENO); 2032 if (startup_pipe == -1) 2033 close(REEXEC_STARTUP_PIPE_FD); 2034 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 2035 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 2036 close(startup_pipe); 2037 startup_pipe = REEXEC_STARTUP_PIPE_FD; 2038 } 2039 2040 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 2041 close(config_s[1]); 2042 2043 execv(rexec_argv[0], rexec_argv); 2044 2045 /* Reexec has failed, fall back and continue */ 2046 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 2047 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 2048 log_init(__progname, options.log_level, 2049 options.log_facility, log_stderr); 2050 2051 /* Clean up fds */ 2052 close(REEXEC_CONFIG_PASS_FD); 2053 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2054 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 2055 dup2(fd, STDIN_FILENO); 2056 dup2(fd, STDOUT_FILENO); 2057 if (fd > STDERR_FILENO) 2058 close(fd); 2059 } 2060 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2061 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2062 } 2063 2064 /* Executed child processes don't need these. */ 2065 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2066 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2067 2068 /* 2069 * Disable the key regeneration alarm. We will not regenerate the 2070 * key since we are no longer in a position to give it to anyone. We 2071 * will not restart on SIGHUP since it no longer makes sense. 2072 */ 2073 alarm(0); 2074 signal(SIGALRM, SIG_DFL); 2075 signal(SIGHUP, SIG_DFL); 2076 signal(SIGTERM, SIG_DFL); 2077 signal(SIGQUIT, SIG_DFL); 2078 signal(SIGCHLD, SIG_DFL); 2079 signal(SIGINT, SIG_DFL); 2080 2081#ifdef __FreeBSD__ 2082 /* 2083 * Initialize the resolver. This may not happen automatically 2084 * before privsep chroot(). 2085 */ 2086 if ((_res.options & RES_INIT) == 0) { 2087 debug("res_init()"); 2088 res_init(); 2089 } 2090#ifdef GSSAPI 2091 /* 2092 * Force GSS-API to parse its configuration and load any 2093 * mechanism plugins. 2094 */ 2095 { 2096 gss_OID_set mechs; 2097 OM_uint32 minor_status; 2098 gss_indicate_mechs(&minor_status, &mechs); 2099 gss_release_oid_set(&minor_status, &mechs); 2100 } 2101#endif 2102#endif 2103 2104 /* 2105 * Register our connection. This turns encryption off because we do 2106 * not have a key. 2107 */ 2108 packet_set_connection(sock_in, sock_out); 2109 packet_set_server(); 2110 ssh = active_state; /* XXX */ 2111 2112 check_ip_options(ssh); 2113 2114 /* Prepare the channels layer */ 2115 channel_init_channels(ssh); 2116 channel_set_af(ssh, options.address_family); 2117 process_permitopen(ssh, &options); 2118 2119 /* Set SO_KEEPALIVE if requested. */ 2120 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 2121 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 2122 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2123 2124 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2125 debug("ssh_remote_port failed"); 2126 cleanup_exit(255); 2127 } 2128 2129 if (options.routing_domain != NULL) 2130 set_process_rdomain(ssh, options.routing_domain); 2131 2132 /* 2133 * The rest of the code depends on the fact that 2134 * ssh_remote_ipaddr() caches the remote ip, even if 2135 * the socket goes away. 2136 */ 2137 remote_ip = ssh_remote_ipaddr(ssh); 2138 2139#ifdef HAVE_LOGIN_CAP 2140 /* Also caches remote hostname for sandboxed child. */ 2141 auth_get_canonical_hostname(ssh, options.use_dns); 2142#endif 2143 2144#ifdef SSH_AUDIT_EVENTS 2145 audit_connection_from(remote_ip, remote_port); 2146#endif 2147#ifdef LIBWRAP 2148 allow_severity = options.log_facility|LOG_INFO; 2149 deny_severity = options.log_facility|LOG_WARNING; 2150 /* Check whether logins are denied from this host. */ 2151 if (packet_connection_is_on_socket()) { 2152 struct request_info req; 2153 2154 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 2155 fromhost(&req); 2156 2157 if (!hosts_access(&req)) { 2158 debug("Connection refused by tcp wrapper"); 2159 refuse(&req); 2160 /* NOTREACHED */ 2161 fatal("libwrap refuse returns"); 2162 } 2163 } 2164#endif /* LIBWRAP */ 2165 2166 rdomain = ssh_packet_rdomain_in(ssh); 2167 2168 /* Log the connection. */ 2169 laddr = get_local_ipaddr(sock_in); 2170 verbose("Connection from %s port %d on %s port %d%s%s%s", 2171 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2172 rdomain == NULL ? "" : " rdomain \"", 2173 rdomain == NULL ? "" : rdomain, 2174 rdomain == NULL ? "" : "\""); 2175 free(laddr); 2176 2177 /* 2178 * We don't want to listen forever unless the other side 2179 * successfully authenticates itself. So we set up an alarm which is 2180 * cleared after successful authentication. A limit of zero 2181 * indicates no limit. Note that we don't set the alarm in debugging 2182 * mode; it is just annoying to have the server exit just when you 2183 * are about to discover the bug. 2184 */ 2185 signal(SIGALRM, grace_alarm_handler); 2186 if (!debug_flag) 2187 alarm(options.login_grace_time); 2188 2189 sshd_exchange_identification(ssh, sock_in, sock_out); 2190 packet_set_nonblocking(); 2191 2192 /* allocate authentication context */ 2193 authctxt = xcalloc(1, sizeof(*authctxt)); 2194 2195 authctxt->loginmsg = loginmsg; 2196 2197 /* XXX global for cleanup, access from other modules */ 2198 the_authctxt = authctxt; 2199 2200 /* Set default key authentication options */ 2201 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2202 fatal("allocation failed"); 2203 2204 /* prepare buffer to collect messages to display to user after login */ 2205 if ((loginmsg = sshbuf_new()) == NULL) 2206 fatal("%s: sshbuf_new failed", __func__); 2207 auth_debug_reset(); 2208 2209 BLACKLIST_INIT(); 2210 2211 if (use_privsep) { 2212 if (privsep_preauth(authctxt) == 1) 2213 goto authenticated; 2214 } else if (have_agent) { 2215 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2216 error("Unable to get agent socket: %s", ssh_err(r)); 2217 have_agent = 0; 2218 } 2219 } 2220 2221 /* perform the key exchange */ 2222 /* authenticate user and start session */ 2223 do_ssh2_kex(); 2224 do_authentication2(authctxt); 2225 2226 /* 2227 * If we use privilege separation, the unprivileged child transfers 2228 * the current keystate and exits 2229 */ 2230 if (use_privsep) { 2231 mm_send_keystate(pmonitor); 2232 packet_clear_keys(); 2233 exit(0); 2234 } 2235 2236 authenticated: 2237 /* 2238 * Cancel the alarm we set to limit the time taken for 2239 * authentication. 2240 */ 2241 alarm(0); 2242 signal(SIGALRM, SIG_DFL); 2243 authctxt->authenticated = 1; 2244 if (startup_pipe != -1) { 2245 close(startup_pipe); 2246 startup_pipe = -1; 2247 } 2248 2249#ifdef SSH_AUDIT_EVENTS 2250 audit_event(SSH_AUTH_SUCCESS); 2251#endif 2252 2253#ifdef GSSAPI 2254 if (options.gss_authentication) { 2255 temporarily_use_uid(authctxt->pw); 2256 ssh_gssapi_storecreds(); 2257 restore_uid(); 2258 } 2259#endif 2260#ifdef USE_PAM 2261 if (options.use_pam) { 2262 do_pam_setcred(1); 2263 do_pam_session(ssh); 2264 } 2265#endif 2266 2267 /* 2268 * In privilege separation, we fork another child and prepare 2269 * file descriptor passing. 2270 */ 2271 if (use_privsep) { 2272 privsep_postauth(authctxt); 2273 /* the monitor process [priv] will not return */ 2274 } 2275 2276 packet_set_timeout(options.client_alive_interval, 2277 options.client_alive_count_max); 2278 2279 /* Try to send all our hostkeys to the client */ 2280 notify_hostkeys(ssh); 2281 2282 /* Start session. */ 2283 do_authenticated(ssh, authctxt); 2284 2285 /* The connection has been terminated. */ 2286 packet_get_bytes(&ibytes, &obytes); 2287 verbose("Transferred: sent %llu, received %llu bytes", 2288 (unsigned long long)obytes, (unsigned long long)ibytes); 2289 2290 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2291 2292#ifdef USE_PAM 2293 if (options.use_pam) 2294 finish_pam(); 2295#endif /* USE_PAM */ 2296 2297#ifdef SSH_AUDIT_EVENTS 2298 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2299#endif 2300 2301 packet_close(); 2302 2303 if (use_privsep) 2304 mm_terminate(); 2305 2306 exit(0); 2307} 2308 2309int 2310sshd_hostkey_sign(struct sshkey *privkey, struct sshkey *pubkey, 2311 u_char **signature, size_t *slenp, const u_char *data, size_t dlen, 2312 const char *alg, u_int flag) 2313{ 2314 int r; 2315 2316 if (privkey) { 2317 if (PRIVSEP(sshkey_sign(privkey, signature, slenp, data, dlen, 2318 alg, datafellows)) < 0) 2319 fatal("%s: key_sign failed", __func__); 2320 } else if (use_privsep) { 2321 if (mm_sshkey_sign(pubkey, signature, slenp, data, dlen, 2322 alg, datafellows) < 0) 2323 fatal("%s: pubkey_sign failed", __func__); 2324 } else { 2325 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slenp, 2326 data, dlen, alg, datafellows)) != 0) 2327 fatal("%s: ssh_agent_sign failed: %s", 2328 __func__, ssh_err(r)); 2329 } 2330 return 0; 2331} 2332 2333/* SSH2 key exchange */ 2334static void 2335do_ssh2_kex(void) 2336{ 2337 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2338 struct kex *kex; 2339 int r; 2340 2341 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2342 options.kex_algorithms); 2343 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2344 options.ciphers); 2345 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2346 options.ciphers); 2347 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2348 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2349 2350 if (options.compression == COMP_NONE) { 2351 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2352 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2353 } 2354 2355 if (options.rekey_limit || options.rekey_interval) 2356 packet_set_rekey_limits(options.rekey_limit, 2357 options.rekey_interval); 2358 2359 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2360 list_hostkey_types()); 2361 2362 /* start key exchange */ 2363 if ((r = kex_setup(active_state, myproposal)) != 0) 2364 fatal("kex_setup: %s", ssh_err(r)); 2365 kex = active_state->kex; 2366#ifdef WITH_OPENSSL 2367 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2368 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2369 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server; 2370 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server; 2371 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server; 2372 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2373 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2374# ifdef OPENSSL_HAS_ECC 2375 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2376# endif 2377#endif 2378 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2379 kex->server = 1; 2380 kex->client_version_string=client_version_string; 2381 kex->server_version_string=server_version_string; 2382 kex->load_host_public_key=&get_hostkey_public_by_type; 2383 kex->load_host_private_key=&get_hostkey_private_by_type; 2384 kex->host_key_index=&get_hostkey_index; 2385 kex->sign = sshd_hostkey_sign; 2386 2387 ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done); 2388 2389 session_id2 = kex->session_id; 2390 session_id2_len = kex->session_id_len; 2391 2392#ifdef DEBUG_KEXDH 2393 /* send 1st encrypted/maced/compressed message */ 2394 packet_start(SSH2_MSG_IGNORE); 2395 packet_put_cstring("markus"); 2396 packet_send(); 2397 packet_write_wait(); 2398#endif 2399 debug("KEX done"); 2400} 2401 2402/* server specific fatal cleanup */ 2403void 2404cleanup_exit(int i) 2405{ 2406 struct ssh *ssh = active_state; /* XXX */ 2407 2408 if (the_authctxt) { 2409 do_cleanup(ssh, the_authctxt); 2410 if (use_privsep && privsep_is_preauth && 2411 pmonitor != NULL && pmonitor->m_pid > 1) { 2412 debug("Killing privsep child %d", pmonitor->m_pid); 2413 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2414 errno != ESRCH) 2415 error("%s: kill(%d): %s", __func__, 2416 pmonitor->m_pid, strerror(errno)); 2417 } 2418 } 2419#ifdef SSH_AUDIT_EVENTS 2420 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2421 if (!use_privsep || mm_is_monitor()) 2422 audit_event(SSH_CONNECTION_ABANDON); 2423#endif 2424 _exit(i); 2425} 2426