sshd.c revision 294693
1/* $OpenBSD: sshd.c,v 1.420 2014/02/26 21:53:37 markus 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: stable/10/crypto/openssh/sshd.c 294693 2016-01-24 22:28:18Z des $"); 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 77#include <openssl/dh.h> 78#include <openssl/bn.h> 79#include <openssl/rand.h> 80#include "openbsd-compat/openssl-compat.h" 81 82#ifdef HAVE_SECUREWARE 83#include <sys/security.h> 84#include <prot.h> 85#endif 86 87#ifdef __FreeBSD__ 88#include <resolv.h> 89#if defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H) 90#include <gssapi/gssapi.h> 91#elif defined(GSSAPI) && defined(HAVE_GSSAPI_H) 92#include <gssapi.h> 93#endif 94#endif 95 96#include "xmalloc.h" 97#include "ssh.h" 98#include "ssh1.h" 99#include "ssh2.h" 100#include "rsa.h" 101#include "sshpty.h" 102#include "packet.h" 103#include "log.h" 104#include "buffer.h" 105#include "servconf.h" 106#include "uidswap.h" 107#include "compat.h" 108#include "cipher.h" 109#include "digest.h" 110#include "key.h" 111#include "kex.h" 112#include "dh.h" 113#include "myproposal.h" 114#include "authfile.h" 115#include "pathnames.h" 116#include "atomicio.h" 117#include "canohost.h" 118#include "hostfile.h" 119#include "auth.h" 120#include "authfd.h" 121#include "misc.h" 122#include "msg.h" 123#include "dispatch.h" 124#include "channels.h" 125#include "session.h" 126#include "monitor_mm.h" 127#include "monitor.h" 128#ifdef GSSAPI 129#include "ssh-gss.h" 130#endif 131#include "monitor_wrap.h" 132#include "roaming.h" 133#include "ssh-sandbox.h" 134#include "version.h" 135 136#ifdef LIBWRAP 137#include <tcpd.h> 138#include <syslog.h> 139int allow_severity; 140int deny_severity; 141#endif /* LIBWRAP */ 142 143#ifndef O_NOCTTY 144#define O_NOCTTY 0 145#endif 146 147/* Re-exec fds */ 148#define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 149#define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 150#define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 151#define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 152 153extern char *__progname; 154 155/* Server configuration options. */ 156ServerOptions options; 157 158/* Name of the server configuration file. */ 159char *config_file_name = _PATH_SERVER_CONFIG_FILE; 160 161/* 162 * Debug mode flag. This can be set on the command line. If debug 163 * mode is enabled, extra debugging output will be sent to the system 164 * log, the daemon will not go to background, and will exit after processing 165 * the first connection. 166 */ 167int debug_flag = 0; 168 169/* Flag indicating that the daemon should only test the configuration and keys. */ 170int test_flag = 0; 171 172/* Flag indicating that the daemon is being started from inetd. */ 173int inetd_flag = 0; 174 175/* Flag indicating that sshd should not detach and become a daemon. */ 176int no_daemon_flag = 0; 177 178/* debug goes to stderr unless inetd_flag is set */ 179int log_stderr = 0; 180 181/* Saved arguments to main(). */ 182char **saved_argv; 183int saved_argc; 184 185/* re-exec */ 186int rexeced_flag = 0; 187int rexec_flag = 1; 188int rexec_argc = 0; 189char **rexec_argv; 190 191/* 192 * The sockets that the server is listening; this is used in the SIGHUP 193 * signal handler. 194 */ 195#define MAX_LISTEN_SOCKS 16 196int listen_socks[MAX_LISTEN_SOCKS]; 197int num_listen_socks = 0; 198 199/* 200 * the client's version string, passed by sshd2 in compat mode. if != NULL, 201 * sshd will skip the version-number exchange 202 */ 203char *client_version_string = NULL; 204char *server_version_string = NULL; 205 206/* for rekeying XXX fixme */ 207Kex *xxx_kex; 208 209/* Daemon's agent connection */ 210AuthenticationConnection *auth_conn = NULL; 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 Key *server_key; /* ephemeral server key */ 223 Key *ssh1_host_key; /* ssh1 host key */ 224 Key **host_keys; /* all private host keys */ 225 Key **host_pubkeys; /* all public host keys */ 226 Key **host_certificates; /* all public host certificates */ 227 int have_ssh1_key; 228 int have_ssh2_key; 229 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 230} sensitive_data; 231 232/* 233 * Flag indicating whether the RSA server key needs to be regenerated. 234 * Is set in the SIGALRM handler and cleared when the key is regenerated. 235 */ 236static volatile sig_atomic_t key_do_regen = 0; 237 238/* This is set to true when a signal is received. */ 239static volatile sig_atomic_t received_sighup = 0; 240static volatile sig_atomic_t received_sigterm = 0; 241 242/* session identifier, used by RSA-auth */ 243u_char session_id[16]; 244 245/* same for ssh2 */ 246u_char *session_id2 = NULL; 247u_int session_id2_len = 0; 248 249/* record remote hostname or ip */ 250u_int utmp_len = MAXHOSTNAMELEN; 251 252/* options.max_startup sized array of fd ints */ 253int *startup_pipes = NULL; 254int startup_pipe; /* in child */ 255 256/* variables used for privilege separation */ 257int use_privsep = -1; 258struct monitor *pmonitor = NULL; 259int privsep_is_preauth = 1; 260 261/* global authentication context */ 262Authctxt *the_authctxt = NULL; 263 264/* sshd_config buffer */ 265Buffer cfg; 266 267/* message to be displayed after login */ 268Buffer loginmsg; 269 270/* Unprivileged user */ 271struct passwd *privsep_pw = NULL; 272 273/* Prototypes for various functions defined later in this file. */ 274void destroy_sensitive_data(void); 275void demote_sensitive_data(void); 276 277static void do_ssh1_kex(void); 278static void do_ssh2_kex(void); 279 280/* 281 * Close all listening sockets 282 */ 283static void 284close_listen_socks(void) 285{ 286 int i; 287 288 for (i = 0; i < num_listen_socks; i++) 289 close(listen_socks[i]); 290 num_listen_socks = -1; 291} 292 293static void 294close_startup_pipes(void) 295{ 296 int i; 297 298 if (startup_pipes) 299 for (i = 0; i < options.max_startups; i++) 300 if (startup_pipes[i] != -1) 301 close(startup_pipes[i]); 302} 303 304/* 305 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 306 * the effect is to reread the configuration file (and to regenerate 307 * the server key). 308 */ 309 310/*ARGSUSED*/ 311static void 312sighup_handler(int sig) 313{ 314 int save_errno = errno; 315 316 received_sighup = 1; 317 signal(SIGHUP, sighup_handler); 318 errno = save_errno; 319} 320 321/* 322 * Called from the main program after receiving SIGHUP. 323 * Restarts the server. 324 */ 325static void 326sighup_restart(void) 327{ 328 logit("Received SIGHUP; restarting."); 329 platform_pre_restart(); 330 close_listen_socks(); 331 close_startup_pipes(); 332 alarm(0); /* alarm timer persists across exec */ 333 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 334 execv(saved_argv[0], saved_argv); 335 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 336 strerror(errno)); 337 exit(1); 338} 339 340/* 341 * Generic signal handler for terminating signals in the master daemon. 342 */ 343/*ARGSUSED*/ 344static void 345sigterm_handler(int sig) 346{ 347 received_sigterm = sig; 348} 349 350/* 351 * SIGCHLD handler. This is called whenever a child dies. This will then 352 * reap any zombies left by exited children. 353 */ 354/*ARGSUSED*/ 355static void 356main_sigchld_handler(int sig) 357{ 358 int save_errno = errno; 359 pid_t pid; 360 int status; 361 362 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 363 (pid < 0 && errno == EINTR)) 364 ; 365 366 signal(SIGCHLD, main_sigchld_handler); 367 errno = save_errno; 368} 369 370/* 371 * Signal handler for the alarm after the login grace period has expired. 372 */ 373/*ARGSUSED*/ 374static void 375grace_alarm_handler(int sig) 376{ 377 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 378 kill(pmonitor->m_pid, SIGALRM); 379 380 /* 381 * Try to kill any processes that we have spawned, E.g. authorized 382 * keys command helpers. 383 */ 384 if (getpgid(0) == getpid()) { 385 signal(SIGTERM, SIG_IGN); 386 kill(0, SIGTERM); 387 } 388 389 /* Log error and exit. */ 390 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 391} 392 393/* 394 * Signal handler for the key regeneration alarm. Note that this 395 * alarm only occurs in the daemon waiting for connections, and it does not 396 * do anything with the private key or random state before forking. 397 * Thus there should be no concurrency control/asynchronous execution 398 * problems. 399 */ 400static void 401generate_ephemeral_server_key(void) 402{ 403 verbose("Generating %s%d bit RSA key.", 404 sensitive_data.server_key ? "new " : "", options.server_key_bits); 405 if (sensitive_data.server_key != NULL) 406 key_free(sensitive_data.server_key); 407 sensitive_data.server_key = key_generate(KEY_RSA1, 408 options.server_key_bits); 409 verbose("RSA key generation complete."); 410 411 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 412} 413 414/*ARGSUSED*/ 415static void 416key_regeneration_alarm(int sig) 417{ 418 int save_errno = errno; 419 420 signal(SIGALRM, SIG_DFL); 421 errno = save_errno; 422 key_do_regen = 1; 423} 424 425static void 426sshd_exchange_identification(int sock_in, int sock_out) 427{ 428 u_int i; 429 int mismatch; 430 int remote_major, remote_minor; 431 int major, minor; 432 char *s, *newline = "\n"; 433 char buf[256]; /* Must not be larger than remote_version. */ 434 char remote_version[256]; /* Must be at least as big as buf. */ 435 436 if ((options.protocol & SSH_PROTO_1) && 437 (options.protocol & SSH_PROTO_2)) { 438 major = PROTOCOL_MAJOR_1; 439 minor = 99; 440 } else if (options.protocol & SSH_PROTO_2) { 441 major = PROTOCOL_MAJOR_2; 442 minor = PROTOCOL_MINOR_2; 443 newline = "\r\n"; 444 } else { 445 major = PROTOCOL_MAJOR_1; 446 minor = PROTOCOL_MINOR_1; 447 } 448 449 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s", 450 major, minor, SSH_VERSION, 451 *options.version_addendum == '\0' ? "" : " ", 452 options.version_addendum, newline); 453 454 /* Send our protocol version identification. */ 455 if (roaming_atomicio(vwrite, sock_out, server_version_string, 456 strlen(server_version_string)) 457 != strlen(server_version_string)) { 458 logit("Could not write ident string to %s", get_remote_ipaddr()); 459 cleanup_exit(255); 460 } 461 462 /* Read other sides version identification. */ 463 memset(buf, 0, sizeof(buf)); 464 for (i = 0; i < sizeof(buf) - 1; i++) { 465 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 466 logit("Did not receive identification string from %s", 467 get_remote_ipaddr()); 468 cleanup_exit(255); 469 } 470 if (buf[i] == '\r') { 471 buf[i] = 0; 472 /* Kludge for F-Secure Macintosh < 1.0.2 */ 473 if (i == 12 && 474 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 475 break; 476 continue; 477 } 478 if (buf[i] == '\n') { 479 buf[i] = 0; 480 break; 481 } 482 } 483 buf[sizeof(buf) - 1] = 0; 484 client_version_string = xstrdup(buf); 485 486 /* 487 * Check that the versions match. In future this might accept 488 * several versions and set appropriate flags to handle them. 489 */ 490 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 491 &remote_major, &remote_minor, remote_version) != 3) { 492 s = "Protocol mismatch.\n"; 493 (void) atomicio(vwrite, sock_out, s, strlen(s)); 494 logit("Bad protocol version identification '%.100s' " 495 "from %s port %d", client_version_string, 496 get_remote_ipaddr(), get_remote_port()); 497 close(sock_in); 498 close(sock_out); 499 cleanup_exit(255); 500 } 501 debug("Client protocol version %d.%d; client software version %.100s", 502 remote_major, remote_minor, remote_version); 503 504 compat_datafellows(remote_version); 505 506 if ((datafellows & SSH_BUG_PROBE) != 0) { 507 logit("probed from %s with %s. Don't panic.", 508 get_remote_ipaddr(), client_version_string); 509 cleanup_exit(255); 510 } 511 if ((datafellows & SSH_BUG_SCANNER) != 0) { 512 logit("scanned from %s with %s. Don't panic.", 513 get_remote_ipaddr(), client_version_string); 514 cleanup_exit(255); 515 } 516 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) { 517 logit("Client version \"%.100s\" uses unsafe RSA signature " 518 "scheme; disabling use of RSA keys", remote_version); 519 } 520 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) { 521 fatal("Client version \"%.100s\" uses unsafe key agreement; " 522 "refusing connection", remote_version); 523 } 524 525 mismatch = 0; 526 switch (remote_major) { 527 case 1: 528 if (remote_minor == 99) { 529 if (options.protocol & SSH_PROTO_2) 530 enable_compat20(); 531 else 532 mismatch = 1; 533 break; 534 } 535 if (!(options.protocol & SSH_PROTO_1)) { 536 mismatch = 1; 537 break; 538 } 539 if (remote_minor < 3) { 540 packet_disconnect("Your ssh version is too old and " 541 "is no longer supported. Please install a newer version."); 542 } else if (remote_minor == 3) { 543 /* note that this disables agent-forwarding */ 544 enable_compat13(); 545 } 546 break; 547 case 2: 548 if (options.protocol & SSH_PROTO_2) { 549 enable_compat20(); 550 break; 551 } 552 /* FALLTHROUGH */ 553 default: 554 mismatch = 1; 555 break; 556 } 557 chop(server_version_string); 558 debug("Local version string %.200s", server_version_string); 559 560 if (mismatch) { 561 s = "Protocol major versions differ.\n"; 562 (void) atomicio(vwrite, sock_out, s, strlen(s)); 563 close(sock_in); 564 close(sock_out); 565 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 566 get_remote_ipaddr(), 567 server_version_string, client_version_string); 568 cleanup_exit(255); 569 } 570} 571 572/* Destroy the host and server keys. They will no longer be needed. */ 573void 574destroy_sensitive_data(void) 575{ 576 int i; 577 578 if (sensitive_data.server_key) { 579 key_free(sensitive_data.server_key); 580 sensitive_data.server_key = NULL; 581 } 582 for (i = 0; i < options.num_host_key_files; i++) { 583 if (sensitive_data.host_keys[i]) { 584 key_free(sensitive_data.host_keys[i]); 585 sensitive_data.host_keys[i] = NULL; 586 } 587 if (sensitive_data.host_certificates[i]) { 588 key_free(sensitive_data.host_certificates[i]); 589 sensitive_data.host_certificates[i] = NULL; 590 } 591 } 592 sensitive_data.ssh1_host_key = NULL; 593 explicit_bzero(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 594} 595 596/* Demote private to public keys for network child */ 597void 598demote_sensitive_data(void) 599{ 600 Key *tmp; 601 int i; 602 603 if (sensitive_data.server_key) { 604 tmp = key_demote(sensitive_data.server_key); 605 key_free(sensitive_data.server_key); 606 sensitive_data.server_key = tmp; 607 } 608 609 for (i = 0; i < options.num_host_key_files; i++) { 610 if (sensitive_data.host_keys[i]) { 611 tmp = key_demote(sensitive_data.host_keys[i]); 612 key_free(sensitive_data.host_keys[i]); 613 sensitive_data.host_keys[i] = tmp; 614 if (tmp->type == KEY_RSA1) 615 sensitive_data.ssh1_host_key = tmp; 616 } 617 /* Certs do not need demotion */ 618 } 619 620 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 621} 622 623static void 624privsep_preauth_child(void) 625{ 626 u_int32_t rnd[256]; 627 gid_t gidset[1]; 628 629 /* Enable challenge-response authentication for privilege separation */ 630 privsep_challenge_enable(); 631 632#ifdef GSSAPI 633 /* Cache supported mechanism OIDs for later use */ 634 if (options.gss_authentication) 635 ssh_gssapi_prepare_supported_oids(); 636#endif 637 638 arc4random_stir(); 639 arc4random_buf(rnd, sizeof(rnd)); 640 RAND_seed(rnd, sizeof(rnd)); 641 explicit_bzero(rnd, sizeof(rnd)); 642 643 /* Demote the private keys to public keys. */ 644 demote_sensitive_data(); 645 646 /* Change our root directory */ 647 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 648 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 649 strerror(errno)); 650 if (chdir("/") == -1) 651 fatal("chdir(\"/\"): %s", strerror(errno)); 652 653 /* Drop our privileges */ 654 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 655 (u_int)privsep_pw->pw_gid); 656#if 0 657 /* XXX not ready, too heavy after chroot */ 658 do_setusercontext(privsep_pw); 659#else 660 gidset[0] = privsep_pw->pw_gid; 661 if (setgroups(1, gidset) < 0) 662 fatal("setgroups: %.100s", strerror(errno)); 663 permanently_set_uid(privsep_pw); 664#endif 665} 666 667static int 668privsep_preauth(Authctxt *authctxt) 669{ 670 int status; 671 pid_t pid; 672 struct ssh_sandbox *box = NULL; 673 674 /* Set up unprivileged child process to deal with network data */ 675 pmonitor = monitor_init(); 676 /* Store a pointer to the kex for later rekeying */ 677 pmonitor->m_pkex = &xxx_kex; 678 679 if (use_privsep == PRIVSEP_ON) 680 box = ssh_sandbox_init(pmonitor); 681 pid = fork(); 682 if (pid == -1) { 683 fatal("fork of unprivileged child failed"); 684 } else if (pid != 0) { 685 debug2("Network child is on pid %ld", (long)pid); 686 687 pmonitor->m_pid = pid; 688 if (have_agent) 689 auth_conn = ssh_get_authentication_connection(); 690 if (box != NULL) 691 ssh_sandbox_parent_preauth(box, pid); 692 monitor_child_preauth(authctxt, pmonitor); 693 694 /* Sync memory */ 695 monitor_sync(pmonitor); 696 697 /* Wait for the child's exit status */ 698 while (waitpid(pid, &status, 0) < 0) { 699 if (errno == EINTR) 700 continue; 701 pmonitor->m_pid = -1; 702 fatal("%s: waitpid: %s", __func__, strerror(errno)); 703 } 704 privsep_is_preauth = 0; 705 pmonitor->m_pid = -1; 706 if (WIFEXITED(status)) { 707 if (WEXITSTATUS(status) != 0) 708 fatal("%s: preauth child exited with status %d", 709 __func__, WEXITSTATUS(status)); 710 } else if (WIFSIGNALED(status)) 711 fatal("%s: preauth child terminated by signal %d", 712 __func__, WTERMSIG(status)); 713 if (box != NULL) 714 ssh_sandbox_parent_finish(box); 715 return 1; 716 } else { 717 /* child */ 718 close(pmonitor->m_sendfd); 719 close(pmonitor->m_log_recvfd); 720 721 /* Arrange for logging to be sent to the monitor */ 722 set_log_handler(mm_log_handler, pmonitor); 723 724 /* Demote the child */ 725 if (getuid() == 0 || geteuid() == 0) 726 privsep_preauth_child(); 727 setproctitle("%s", "[net]"); 728 if (box != NULL) 729 ssh_sandbox_child(box); 730 731 return 0; 732 } 733} 734 735static void 736privsep_postauth(Authctxt *authctxt) 737{ 738 u_int32_t rnd[256]; 739 740#ifdef DISABLE_FD_PASSING 741 if (1) { 742#else 743 if (authctxt->pw->pw_uid == 0 || options.use_login) { 744#endif 745 /* File descriptor passing is broken or root login */ 746 use_privsep = 0; 747 goto skip; 748 } 749 750 /* New socket pair */ 751 monitor_reinit(pmonitor); 752 753 pmonitor->m_pid = fork(); 754 if (pmonitor->m_pid == -1) 755 fatal("fork of unprivileged child failed"); 756 else if (pmonitor->m_pid != 0) { 757 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 758 buffer_clear(&loginmsg); 759 monitor_child_postauth(pmonitor); 760 761 /* NEVERREACHED */ 762 exit(0); 763 } 764 765 /* child */ 766 767 close(pmonitor->m_sendfd); 768 pmonitor->m_sendfd = -1; 769 770 /* Demote the private keys to public keys. */ 771 demote_sensitive_data(); 772 773 arc4random_stir(); 774 arc4random_buf(rnd, sizeof(rnd)); 775 RAND_seed(rnd, sizeof(rnd)); 776 explicit_bzero(rnd, sizeof(rnd)); 777 778 /* Drop privileges */ 779 do_setusercontext(authctxt->pw); 780 781 skip: 782 /* It is safe now to apply the key state */ 783 monitor_apply_keystate(pmonitor); 784 785 /* 786 * Tell the packet layer that authentication was successful, since 787 * this information is not part of the key state. 788 */ 789 packet_set_authenticated(); 790} 791 792static char * 793list_hostkey_types(void) 794{ 795 Buffer b; 796 const char *p; 797 char *ret; 798 int i; 799 Key *key; 800 801 buffer_init(&b); 802 for (i = 0; i < options.num_host_key_files; i++) { 803 key = sensitive_data.host_keys[i]; 804 if (key == NULL) 805 key = sensitive_data.host_pubkeys[i]; 806 if (key == NULL) 807 continue; 808 switch (key->type) { 809 case KEY_RSA: 810 case KEY_DSA: 811 case KEY_ECDSA: 812 case KEY_ED25519: 813 if (buffer_len(&b) > 0) 814 buffer_append(&b, ",", 1); 815 p = key_ssh_name(key); 816 buffer_append(&b, p, strlen(p)); 817 break; 818 } 819 /* If the private key has a cert peer, then list that too */ 820 key = sensitive_data.host_certificates[i]; 821 if (key == NULL) 822 continue; 823 switch (key->type) { 824 case KEY_RSA_CERT_V00: 825 case KEY_DSA_CERT_V00: 826 case KEY_RSA_CERT: 827 case KEY_DSA_CERT: 828 case KEY_ECDSA_CERT: 829 case KEY_ED25519_CERT: 830 if (buffer_len(&b) > 0) 831 buffer_append(&b, ",", 1); 832 p = key_ssh_name(key); 833 buffer_append(&b, p, strlen(p)); 834 break; 835 } 836 } 837 buffer_append(&b, "\0", 1); 838 ret = xstrdup(buffer_ptr(&b)); 839 buffer_free(&b); 840 debug("list_hostkey_types: %s", ret); 841 return ret; 842} 843 844static Key * 845get_hostkey_by_type(int type, int need_private) 846{ 847 int i; 848 Key *key; 849 850 for (i = 0; i < options.num_host_key_files; i++) { 851 switch (type) { 852 case KEY_RSA_CERT_V00: 853 case KEY_DSA_CERT_V00: 854 case KEY_RSA_CERT: 855 case KEY_DSA_CERT: 856 case KEY_ECDSA_CERT: 857 case KEY_ED25519_CERT: 858 key = sensitive_data.host_certificates[i]; 859 break; 860 default: 861 key = sensitive_data.host_keys[i]; 862 if (key == NULL && !need_private) 863 key = sensitive_data.host_pubkeys[i]; 864 break; 865 } 866 if (key != NULL && key->type == type) 867 return need_private ? 868 sensitive_data.host_keys[i] : key; 869 } 870 return NULL; 871} 872 873Key * 874get_hostkey_public_by_type(int type) 875{ 876 return get_hostkey_by_type(type, 0); 877} 878 879Key * 880get_hostkey_private_by_type(int type) 881{ 882 return get_hostkey_by_type(type, 1); 883} 884 885Key * 886get_hostkey_by_index(int ind) 887{ 888 if (ind < 0 || ind >= options.num_host_key_files) 889 return (NULL); 890 return (sensitive_data.host_keys[ind]); 891} 892 893Key * 894get_hostkey_public_by_index(int ind) 895{ 896 if (ind < 0 || ind >= options.num_host_key_files) 897 return (NULL); 898 return (sensitive_data.host_pubkeys[ind]); 899} 900 901int 902get_hostkey_index(Key *key) 903{ 904 int i; 905 906 for (i = 0; i < options.num_host_key_files; i++) { 907 if (key_is_cert(key)) { 908 if (key == sensitive_data.host_certificates[i]) 909 return (i); 910 } else { 911 if (key == sensitive_data.host_keys[i]) 912 return (i); 913 if (key == sensitive_data.host_pubkeys[i]) 914 return (i); 915 } 916 } 917 return (-1); 918} 919 920/* 921 * returns 1 if connection should be dropped, 0 otherwise. 922 * dropping starts at connection #max_startups_begin with a probability 923 * of (max_startups_rate/100). the probability increases linearly until 924 * all connections are dropped for startups > max_startups 925 */ 926static int 927drop_connection(int startups) 928{ 929 int p, r; 930 931 if (startups < options.max_startups_begin) 932 return 0; 933 if (startups >= options.max_startups) 934 return 1; 935 if (options.max_startups_rate == 100) 936 return 1; 937 938 p = 100 - options.max_startups_rate; 939 p *= startups - options.max_startups_begin; 940 p /= options.max_startups - options.max_startups_begin; 941 p += options.max_startups_rate; 942 r = arc4random_uniform(100); 943 944 debug("drop_connection: p %d, r %d", p, r); 945 return (r < p) ? 1 : 0; 946} 947 948static void 949usage(void) 950{ 951 if (options.version_addendum && *options.version_addendum != '\0') 952 fprintf(stderr, "%s %s, %s\n", 953 SSH_RELEASE, 954 options.version_addendum, SSLeay_version(SSLEAY_VERSION)); 955 else 956 fprintf(stderr, "%s, %s\n", 957 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); 958 fprintf(stderr, 959"usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 960" [-E log_file] [-f config_file] [-g login_grace_time]\n" 961" [-h host_key_file] [-k key_gen_time] [-o option] [-p port]\n" 962" [-u len]\n" 963 ); 964 exit(1); 965} 966 967static void 968send_rexec_state(int fd, Buffer *conf) 969{ 970 Buffer m; 971 972 debug3("%s: entering fd = %d config len %d", __func__, fd, 973 buffer_len(conf)); 974 975 /* 976 * Protocol from reexec master to child: 977 * string configuration 978 * u_int ephemeral_key_follows 979 * bignum e (only if ephemeral_key_follows == 1) 980 * bignum n " 981 * bignum d " 982 * bignum iqmp " 983 * bignum p " 984 * bignum q " 985 * string rngseed (only if OpenSSL is not self-seeded) 986 */ 987 buffer_init(&m); 988 buffer_put_cstring(&m, buffer_ptr(conf)); 989 990 if (sensitive_data.server_key != NULL && 991 sensitive_data.server_key->type == KEY_RSA1) { 992 buffer_put_int(&m, 1); 993 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 994 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 995 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 996 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 997 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 998 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 999 } else 1000 buffer_put_int(&m, 0); 1001 1002#ifndef OPENSSL_PRNG_ONLY 1003 rexec_send_rng_seed(&m); 1004#endif 1005 1006 if (ssh_msg_send(fd, 0, &m) == -1) 1007 fatal("%s: ssh_msg_send failed", __func__); 1008 1009 buffer_free(&m); 1010 1011 debug3("%s: done", __func__); 1012} 1013 1014static void 1015recv_rexec_state(int fd, Buffer *conf) 1016{ 1017 Buffer m; 1018 char *cp; 1019 u_int len; 1020 1021 debug3("%s: entering fd = %d", __func__, fd); 1022 1023 buffer_init(&m); 1024 1025 if (ssh_msg_recv(fd, &m) == -1) 1026 fatal("%s: ssh_msg_recv failed", __func__); 1027 if (buffer_get_char(&m) != 0) 1028 fatal("%s: rexec version mismatch", __func__); 1029 1030 cp = buffer_get_string(&m, &len); 1031 if (conf != NULL) 1032 buffer_append(conf, cp, len + 1); 1033 free(cp); 1034 1035 if (buffer_get_int(&m)) { 1036 if (sensitive_data.server_key != NULL) 1037 key_free(sensitive_data.server_key); 1038 sensitive_data.server_key = key_new_private(KEY_RSA1); 1039 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 1040 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 1041 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 1042 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 1043 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 1044 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 1045 rsa_generate_additional_parameters( 1046 sensitive_data.server_key->rsa); 1047 } 1048 1049#ifndef OPENSSL_PRNG_ONLY 1050 rexec_recv_rng_seed(&m); 1051#endif 1052 1053 buffer_free(&m); 1054 1055 debug3("%s: done", __func__); 1056} 1057 1058/* Accept a connection from inetd */ 1059static void 1060server_accept_inetd(int *sock_in, int *sock_out) 1061{ 1062 int fd; 1063 1064 startup_pipe = -1; 1065 if (rexeced_flag) { 1066 close(REEXEC_CONFIG_PASS_FD); 1067 *sock_in = *sock_out = dup(STDIN_FILENO); 1068 if (!debug_flag) { 1069 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1070 close(REEXEC_STARTUP_PIPE_FD); 1071 } 1072 } else { 1073 *sock_in = dup(STDIN_FILENO); 1074 *sock_out = dup(STDOUT_FILENO); 1075 } 1076 /* 1077 * We intentionally do not close the descriptors 0, 1, and 2 1078 * as our code for setting the descriptors won't work if 1079 * ttyfd happens to be one of those. 1080 */ 1081 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1082 dup2(fd, STDIN_FILENO); 1083 dup2(fd, STDOUT_FILENO); 1084 if (!log_stderr) 1085 dup2(fd, STDERR_FILENO); 1086 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1087 close(fd); 1088 } 1089 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1090} 1091 1092/* 1093 * Listen for TCP connections 1094 */ 1095static void 1096server_listen(void) 1097{ 1098 int ret, listen_sock, on = 1; 1099 struct addrinfo *ai; 1100 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1101 int socksize; 1102 socklen_t len; 1103 1104 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1105 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1106 continue; 1107 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1108 fatal("Too many listen sockets. " 1109 "Enlarge MAX_LISTEN_SOCKS"); 1110 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1111 ntop, sizeof(ntop), strport, sizeof(strport), 1112 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1113 error("getnameinfo failed: %.100s", 1114 ssh_gai_strerror(ret)); 1115 continue; 1116 } 1117 /* Create socket for listening. */ 1118 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1119 ai->ai_protocol); 1120 if (listen_sock < 0) { 1121 /* kernel may not support ipv6 */ 1122 verbose("socket: %.100s", strerror(errno)); 1123 continue; 1124 } 1125 if (set_nonblock(listen_sock) == -1) { 1126 close(listen_sock); 1127 continue; 1128 } 1129 /* 1130 * Set socket options. 1131 * Allow local port reuse in TIME_WAIT. 1132 */ 1133 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1134 &on, sizeof(on)) == -1) 1135 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1136 1137 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1138 if (ai->ai_family == AF_INET6) 1139 sock_set_v6only(listen_sock); 1140 1141 debug("Bind to port %s on %s.", strport, ntop); 1142 1143 len = sizeof(socksize); 1144 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len); 1145 debug("Server TCP RWIN socket size: %d", socksize); 1146 1147 /* Bind the socket to the desired port. */ 1148 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1149 error("Bind to port %s on %s failed: %.200s.", 1150 strport, ntop, strerror(errno)); 1151 close(listen_sock); 1152 continue; 1153 } 1154 listen_socks[num_listen_socks] = listen_sock; 1155 num_listen_socks++; 1156 1157 /* Start listening on the port. */ 1158 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1159 fatal("listen on [%s]:%s: %.100s", 1160 ntop, strport, strerror(errno)); 1161 logit("Server listening on %s port %s.", ntop, strport); 1162 } 1163 freeaddrinfo(options.listen_addrs); 1164 1165 if (!num_listen_socks) 1166 fatal("Cannot bind any address."); 1167} 1168 1169/* 1170 * The main TCP accept loop. Note that, for the non-debug case, returns 1171 * from this function are in a forked subprocess. 1172 */ 1173static void 1174server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1175{ 1176 fd_set *fdset; 1177 int i, j, ret, maxfd; 1178 int key_used = 0, startups = 0; 1179 int startup_p[2] = { -1 , -1 }; 1180 struct sockaddr_storage from; 1181 socklen_t fromlen; 1182 pid_t pid; 1183 u_char rnd[256]; 1184 1185 /* setup fd set for accept */ 1186 fdset = NULL; 1187 maxfd = 0; 1188 for (i = 0; i < num_listen_socks; i++) 1189 if (listen_socks[i] > maxfd) 1190 maxfd = listen_socks[i]; 1191 /* pipes connected to unauthenticated childs */ 1192 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1193 for (i = 0; i < options.max_startups; i++) 1194 startup_pipes[i] = -1; 1195 1196 /* 1197 * Stay listening for connections until the system crashes or 1198 * the daemon is killed with a signal. 1199 */ 1200 for (;;) { 1201 if (received_sighup) 1202 sighup_restart(); 1203 if (fdset != NULL) 1204 free(fdset); 1205 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1206 sizeof(fd_mask)); 1207 1208 for (i = 0; i < num_listen_socks; i++) 1209 FD_SET(listen_socks[i], fdset); 1210 for (i = 0; i < options.max_startups; i++) 1211 if (startup_pipes[i] != -1) 1212 FD_SET(startup_pipes[i], fdset); 1213 1214 /* Wait in select until there is a connection. */ 1215 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1216 if (ret < 0 && errno != EINTR) 1217 error("select: %.100s", strerror(errno)); 1218 if (received_sigterm) { 1219 logit("Received signal %d; terminating.", 1220 (int) received_sigterm); 1221 close_listen_socks(); 1222 unlink(options.pid_file); 1223 exit(received_sigterm == SIGTERM ? 0 : 255); 1224 } 1225 if (key_used && key_do_regen) { 1226 generate_ephemeral_server_key(); 1227 key_used = 0; 1228 key_do_regen = 0; 1229 } 1230 if (ret < 0) 1231 continue; 1232 1233 for (i = 0; i < options.max_startups; i++) 1234 if (startup_pipes[i] != -1 && 1235 FD_ISSET(startup_pipes[i], fdset)) { 1236 /* 1237 * the read end of the pipe is ready 1238 * if the child has closed the pipe 1239 * after successful authentication 1240 * or if the child has died 1241 */ 1242 close(startup_pipes[i]); 1243 startup_pipes[i] = -1; 1244 startups--; 1245 } 1246 for (i = 0; i < num_listen_socks; i++) { 1247 if (!FD_ISSET(listen_socks[i], fdset)) 1248 continue; 1249 fromlen = sizeof(from); 1250 *newsock = accept(listen_socks[i], 1251 (struct sockaddr *)&from, &fromlen); 1252 if (*newsock < 0) { 1253 if (errno != EINTR && errno != EWOULDBLOCK && 1254 errno != ECONNABORTED && errno != EAGAIN) 1255 error("accept: %.100s", 1256 strerror(errno)); 1257 if (errno == EMFILE || errno == ENFILE) 1258 usleep(100 * 1000); 1259 continue; 1260 } 1261 if (unset_nonblock(*newsock) == -1) { 1262 close(*newsock); 1263 continue; 1264 } 1265 if (drop_connection(startups) == 1) { 1266 debug("drop connection #%d", startups); 1267 close(*newsock); 1268 continue; 1269 } 1270 if (pipe(startup_p) == -1) { 1271 close(*newsock); 1272 continue; 1273 } 1274 1275 if (rexec_flag && socketpair(AF_UNIX, 1276 SOCK_STREAM, 0, config_s) == -1) { 1277 error("reexec socketpair: %s", 1278 strerror(errno)); 1279 close(*newsock); 1280 close(startup_p[0]); 1281 close(startup_p[1]); 1282 continue; 1283 } 1284 1285 for (j = 0; j < options.max_startups; j++) 1286 if (startup_pipes[j] == -1) { 1287 startup_pipes[j] = startup_p[0]; 1288 if (maxfd < startup_p[0]) 1289 maxfd = startup_p[0]; 1290 startups++; 1291 break; 1292 } 1293 1294 /* 1295 * Got connection. Fork a child to handle it, unless 1296 * we are in debugging mode. 1297 */ 1298 if (debug_flag) { 1299 /* 1300 * In debugging mode. Close the listening 1301 * socket, and start processing the 1302 * connection without forking. 1303 */ 1304 debug("Server will not fork when running in debugging mode."); 1305 close_listen_socks(); 1306 *sock_in = *newsock; 1307 *sock_out = *newsock; 1308 close(startup_p[0]); 1309 close(startup_p[1]); 1310 startup_pipe = -1; 1311 pid = getpid(); 1312 if (rexec_flag) { 1313 send_rexec_state(config_s[0], 1314 &cfg); 1315 close(config_s[0]); 1316 } 1317 break; 1318 } 1319 1320 /* 1321 * Normal production daemon. Fork, and have 1322 * the child process the connection. The 1323 * parent continues listening. 1324 */ 1325 platform_pre_fork(); 1326 if ((pid = fork()) == 0) { 1327 /* 1328 * Child. Close the listening and 1329 * max_startup sockets. Start using 1330 * the accepted socket. Reinitialize 1331 * logging (since our pid has changed). 1332 * We break out of the loop to handle 1333 * the connection. 1334 */ 1335 platform_post_fork_child(); 1336 startup_pipe = startup_p[1]; 1337 close_startup_pipes(); 1338 close_listen_socks(); 1339 *sock_in = *newsock; 1340 *sock_out = *newsock; 1341 log_init(__progname, 1342 options.log_level, 1343 options.log_facility, 1344 log_stderr); 1345 if (rexec_flag) 1346 close(config_s[0]); 1347 break; 1348 } 1349 1350 /* Parent. Stay in the loop. */ 1351 platform_post_fork_parent(pid); 1352 if (pid < 0) 1353 error("fork: %.100s", strerror(errno)); 1354 else 1355 debug("Forked child %ld.", (long)pid); 1356 1357 close(startup_p[1]); 1358 1359 if (rexec_flag) { 1360 send_rexec_state(config_s[0], &cfg); 1361 close(config_s[0]); 1362 close(config_s[1]); 1363 } 1364 1365 /* 1366 * Mark that the key has been used (it 1367 * was "given" to the child). 1368 */ 1369 if ((options.protocol & SSH_PROTO_1) && 1370 key_used == 0) { 1371 /* Schedule server key regeneration alarm. */ 1372 signal(SIGALRM, key_regeneration_alarm); 1373 alarm(options.key_regeneration_time); 1374 key_used = 1; 1375 } 1376 1377 close(*newsock); 1378 1379 /* 1380 * Ensure that our random state differs 1381 * from that of the child 1382 */ 1383 arc4random_stir(); 1384 arc4random_buf(rnd, sizeof(rnd)); 1385 RAND_seed(rnd, sizeof(rnd)); 1386 explicit_bzero(rnd, sizeof(rnd)); 1387 } 1388 1389 /* child process check (or debug mode) */ 1390 if (num_listen_socks < 0) 1391 break; 1392 } 1393} 1394 1395 1396/* 1397 * Main program for the daemon. 1398 */ 1399int 1400main(int ac, char **av) 1401{ 1402 extern char *optarg; 1403 extern int optind; 1404 int opt, i, j, on = 1; 1405 int sock_in = -1, sock_out = -1, newsock = -1; 1406 const char *remote_ip; 1407 int remote_port; 1408 char *line, *logfile = NULL; 1409 int config_s[2] = { -1 , -1 }; 1410 u_int n; 1411 u_int64_t ibytes, obytes; 1412 mode_t new_umask; 1413 Key *key; 1414 Key *pubkey; 1415 int keytype; 1416 Authctxt *authctxt; 1417 struct connection_info *connection_info = get_connection_info(0, 0); 1418 1419#ifdef HAVE_SECUREWARE 1420 (void)set_auth_parameters(ac, av); 1421#endif 1422 __progname = ssh_get_progname(av[0]); 1423 1424 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1425 saved_argc = ac; 1426 rexec_argc = ac; 1427 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1428 for (i = 0; i < ac; i++) 1429 saved_argv[i] = xstrdup(av[i]); 1430 saved_argv[i] = NULL; 1431 1432#ifndef HAVE_SETPROCTITLE 1433 /* Prepare for later setproctitle emulation */ 1434 compat_init_setproctitle(ac, av); 1435 av = saved_argv; 1436#endif 1437 1438 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1439 debug("setgroups(): %.200s", strerror(errno)); 1440 1441 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1442 sanitise_stdfd(); 1443 1444 /* Initialize configuration options to their default values. */ 1445 initialize_server_options(&options); 1446 1447 /* Parse command-line arguments. */ 1448 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeE:iqrtQRT46")) != -1) { 1449 switch (opt) { 1450 case '4': 1451 options.address_family = AF_INET; 1452 break; 1453 case '6': 1454 options.address_family = AF_INET6; 1455 break; 1456 case 'f': 1457 config_file_name = optarg; 1458 break; 1459 case 'c': 1460 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1461 fprintf(stderr, "too many host certificates.\n"); 1462 exit(1); 1463 } 1464 options.host_cert_files[options.num_host_cert_files++] = 1465 derelativise_path(optarg); 1466 break; 1467 case 'd': 1468 if (debug_flag == 0) { 1469 debug_flag = 1; 1470 options.log_level = SYSLOG_LEVEL_DEBUG1; 1471 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1472 options.log_level++; 1473 break; 1474 case 'D': 1475 no_daemon_flag = 1; 1476 break; 1477 case 'E': 1478 logfile = xstrdup(optarg); 1479 /* FALLTHROUGH */ 1480 case 'e': 1481 log_stderr = 1; 1482 break; 1483 case 'i': 1484 inetd_flag = 1; 1485 break; 1486 case 'r': 1487 rexec_flag = 0; 1488 break; 1489 case 'R': 1490 rexeced_flag = 1; 1491 inetd_flag = 1; 1492 break; 1493 case 'Q': 1494 /* ignored */ 1495 break; 1496 case 'q': 1497 options.log_level = SYSLOG_LEVEL_QUIET; 1498 break; 1499 case 'b': 1500 options.server_key_bits = (int)strtonum(optarg, 256, 1501 32768, NULL); 1502 break; 1503 case 'p': 1504 options.ports_from_cmdline = 1; 1505 if (options.num_ports >= MAX_PORTS) { 1506 fprintf(stderr, "too many ports.\n"); 1507 exit(1); 1508 } 1509 options.ports[options.num_ports++] = a2port(optarg); 1510 if (options.ports[options.num_ports-1] <= 0) { 1511 fprintf(stderr, "Bad port number.\n"); 1512 exit(1); 1513 } 1514 break; 1515 case 'g': 1516 if ((options.login_grace_time = convtime(optarg)) == -1) { 1517 fprintf(stderr, "Invalid login grace time.\n"); 1518 exit(1); 1519 } 1520 break; 1521 case 'k': 1522 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1523 fprintf(stderr, "Invalid key regeneration interval.\n"); 1524 exit(1); 1525 } 1526 break; 1527 case 'h': 1528 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1529 fprintf(stderr, "too many host keys.\n"); 1530 exit(1); 1531 } 1532 options.host_key_files[options.num_host_key_files++] = 1533 derelativise_path(optarg); 1534 break; 1535 case 't': 1536 test_flag = 1; 1537 break; 1538 case 'T': 1539 test_flag = 2; 1540 break; 1541 case 'C': 1542 if (parse_server_match_testspec(connection_info, 1543 optarg) == -1) 1544 exit(1); 1545 break; 1546 case 'u': 1547 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1548 if (utmp_len > MAXHOSTNAMELEN) { 1549 fprintf(stderr, "Invalid utmp length.\n"); 1550 exit(1); 1551 } 1552 break; 1553 case 'o': 1554 line = xstrdup(optarg); 1555 if (process_server_config_line(&options, line, 1556 "command-line", 0, NULL, NULL) != 0) 1557 exit(1); 1558 free(line); 1559 break; 1560 case '?': 1561 default: 1562 usage(); 1563 break; 1564 } 1565 } 1566 if (rexeced_flag || inetd_flag) 1567 rexec_flag = 0; 1568 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1569 fatal("sshd re-exec requires execution with an absolute path"); 1570 if (rexeced_flag) 1571 closefrom(REEXEC_MIN_FREE_FD); 1572 else 1573 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1574 1575 OpenSSL_add_all_algorithms(); 1576 1577 /* If requested, redirect the logs to the specified logfile. */ 1578 if (logfile != NULL) { 1579 log_redirect_stderr_to(logfile); 1580 free(logfile); 1581 } 1582 /* 1583 * Force logging to stderr until we have loaded the private host 1584 * key (unless started from inetd) 1585 */ 1586 log_init(__progname, 1587 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1588 SYSLOG_LEVEL_INFO : options.log_level, 1589 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1590 SYSLOG_FACILITY_AUTH : options.log_facility, 1591 log_stderr || !inetd_flag); 1592 1593 /* 1594 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1595 * root's environment 1596 */ 1597 if (getenv("KRB5CCNAME") != NULL) 1598 (void) unsetenv("KRB5CCNAME"); 1599 1600#ifdef _UNICOS 1601 /* Cray can define user privs drop all privs now! 1602 * Not needed on PRIV_SU systems! 1603 */ 1604 drop_cray_privs(); 1605#endif 1606 1607 sensitive_data.server_key = NULL; 1608 sensitive_data.ssh1_host_key = NULL; 1609 sensitive_data.have_ssh1_key = 0; 1610 sensitive_data.have_ssh2_key = 0; 1611 1612 /* 1613 * If we're doing an extended config test, make sure we have all of 1614 * the parameters we need. If we're not doing an extended test, 1615 * do not silently ignore connection test params. 1616 */ 1617 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0) 1618 fatal("user, host and addr are all required when testing " 1619 "Match configs"); 1620 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0) 1621 fatal("Config test connection parameter (-C) provided without " 1622 "test mode (-T)"); 1623 1624 /* Fetch our configuration */ 1625 buffer_init(&cfg); 1626 if (rexeced_flag) 1627 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1628 else 1629 load_server_config(config_file_name, &cfg); 1630 1631 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1632 &cfg, NULL); 1633 1634 seed_rng(); 1635 1636 /* Fill in default values for those options not explicitly set. */ 1637 fill_default_server_options(&options); 1638 1639 /* challenge-response is implemented via keyboard interactive */ 1640 if (options.challenge_response_authentication) 1641 options.kbd_interactive_authentication = 1; 1642 1643 /* Check that options are sensible */ 1644 if (options.authorized_keys_command_user == NULL && 1645 (options.authorized_keys_command != NULL && 1646 strcasecmp(options.authorized_keys_command, "none") != 0)) 1647 fatal("AuthorizedKeysCommand set without " 1648 "AuthorizedKeysCommandUser"); 1649 1650 /* 1651 * Check whether there is any path through configured auth methods. 1652 * Unfortunately it is not possible to verify this generally before 1653 * daemonisation in the presence of Match block, but this catches 1654 * and warns for trivial misconfigurations that could break login. 1655 */ 1656 if (options.num_auth_methods != 0) { 1657 if ((options.protocol & SSH_PROTO_1)) 1658 fatal("AuthenticationMethods is not supported with " 1659 "SSH protocol 1"); 1660 for (n = 0; n < options.num_auth_methods; n++) { 1661 if (auth2_methods_valid(options.auth_methods[n], 1662 1) == 0) 1663 break; 1664 } 1665 if (n >= options.num_auth_methods) 1666 fatal("AuthenticationMethods cannot be satisfied by " 1667 "enabled authentication methods"); 1668 } 1669 1670 /* set default channel AF */ 1671 channel_set_af(options.address_family); 1672 1673 /* Check that there are no remaining arguments. */ 1674 if (optind < ac) { 1675 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1676 exit(1); 1677 } 1678 1679 debug("sshd version %s, %s", SSH_VERSION, 1680 SSLeay_version(SSLEAY_VERSION)); 1681 1682 /* Store privilege separation user for later use if required. */ 1683 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1684 if (use_privsep || options.kerberos_authentication) 1685 fatal("Privilege separation user %s does not exist", 1686 SSH_PRIVSEP_USER); 1687 } else { 1688 explicit_bzero(privsep_pw->pw_passwd, 1689 strlen(privsep_pw->pw_passwd)); 1690 privsep_pw = pwcopy(privsep_pw); 1691 free(privsep_pw->pw_passwd); 1692 privsep_pw->pw_passwd = xstrdup("*"); 1693 } 1694 endpwent(); 1695 1696 /* load host keys */ 1697 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1698 sizeof(Key *)); 1699 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1700 sizeof(Key *)); 1701 for (i = 0; i < options.num_host_key_files; i++) { 1702 sensitive_data.host_keys[i] = NULL; 1703 sensitive_data.host_pubkeys[i] = NULL; 1704 } 1705 1706 if (options.host_key_agent) { 1707 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1708 setenv(SSH_AUTHSOCKET_ENV_NAME, 1709 options.host_key_agent, 1); 1710 have_agent = ssh_agent_present(); 1711 } 1712 1713 for (i = 0; i < options.num_host_key_files; i++) { 1714 key = key_load_private(options.host_key_files[i], "", NULL); 1715 pubkey = key_load_public(options.host_key_files[i], NULL); 1716 sensitive_data.host_keys[i] = key; 1717 sensitive_data.host_pubkeys[i] = pubkey; 1718 1719 if (key == NULL && pubkey != NULL && pubkey->type != KEY_RSA1 && 1720 have_agent) { 1721 debug("will rely on agent for hostkey %s", 1722 options.host_key_files[i]); 1723 keytype = pubkey->type; 1724 } else if (key != NULL) { 1725 keytype = key->type; 1726 } else { 1727 error("Could not load host key: %s", 1728 options.host_key_files[i]); 1729 sensitive_data.host_keys[i] = NULL; 1730 sensitive_data.host_pubkeys[i] = NULL; 1731 continue; 1732 } 1733 1734 switch (keytype) { 1735 case KEY_RSA1: 1736 sensitive_data.ssh1_host_key = key; 1737 sensitive_data.have_ssh1_key = 1; 1738 break; 1739 case KEY_RSA: 1740 case KEY_DSA: 1741 case KEY_ECDSA: 1742 case KEY_ED25519: 1743 sensitive_data.have_ssh2_key = 1; 1744 break; 1745 } 1746 debug("private host key: #%d type %d %s", i, keytype, 1747 key_type(key ? key : pubkey)); 1748 } 1749 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1750 logit("Disabling protocol version 1. Could not load host key"); 1751 options.protocol &= ~SSH_PROTO_1; 1752 } 1753 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1754 logit("Disabling protocol version 2. Could not load host key"); 1755 options.protocol &= ~SSH_PROTO_2; 1756 } 1757 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1758 logit("sshd: no hostkeys available -- exiting."); 1759 exit(1); 1760 } 1761 1762 /* 1763 * Load certificates. They are stored in an array at identical 1764 * indices to the public keys that they relate to. 1765 */ 1766 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1767 sizeof(Key *)); 1768 for (i = 0; i < options.num_host_key_files; i++) 1769 sensitive_data.host_certificates[i] = NULL; 1770 1771 for (i = 0; i < options.num_host_cert_files; i++) { 1772 key = key_load_public(options.host_cert_files[i], NULL); 1773 if (key == NULL) { 1774 error("Could not load host certificate: %s", 1775 options.host_cert_files[i]); 1776 continue; 1777 } 1778 if (!key_is_cert(key)) { 1779 error("Certificate file is not a certificate: %s", 1780 options.host_cert_files[i]); 1781 key_free(key); 1782 continue; 1783 } 1784 /* Find matching private key */ 1785 for (j = 0; j < options.num_host_key_files; j++) { 1786 if (key_equal_public(key, 1787 sensitive_data.host_keys[j])) { 1788 sensitive_data.host_certificates[j] = key; 1789 break; 1790 } 1791 } 1792 if (j >= options.num_host_key_files) { 1793 error("No matching private key for certificate: %s", 1794 options.host_cert_files[i]); 1795 key_free(key); 1796 continue; 1797 } 1798 sensitive_data.host_certificates[j] = key; 1799 debug("host certificate: #%d type %d %s", j, key->type, 1800 key_type(key)); 1801 } 1802 /* Check certain values for sanity. */ 1803 if (options.protocol & SSH_PROTO_1) { 1804 if (options.server_key_bits < 512 || 1805 options.server_key_bits > 32768) { 1806 fprintf(stderr, "Bad server key size.\n"); 1807 exit(1); 1808 } 1809 /* 1810 * Check that server and host key lengths differ sufficiently. This 1811 * is necessary to make double encryption work with rsaref. Oh, I 1812 * hate software patents. I dont know if this can go? Niels 1813 */ 1814 if (options.server_key_bits > 1815 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1816 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1817 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1818 SSH_KEY_BITS_RESERVED) { 1819 options.server_key_bits = 1820 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1821 SSH_KEY_BITS_RESERVED; 1822 debug("Forcing server key to %d bits to make it differ from host key.", 1823 options.server_key_bits); 1824 } 1825 } 1826 1827 if (use_privsep) { 1828 struct stat st; 1829 1830 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1831 (S_ISDIR(st.st_mode) == 0)) 1832 fatal("Missing privilege separation directory: %s", 1833 _PATH_PRIVSEP_CHROOT_DIR); 1834 1835#ifdef HAVE_CYGWIN 1836 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1837 (st.st_uid != getuid () || 1838 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1839#else 1840 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1841#endif 1842 fatal("%s must be owned by root and not group or " 1843 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1844 } 1845 1846 if (test_flag > 1) { 1847 if (server_match_spec_complete(connection_info) == 1) 1848 parse_server_match_config(&options, connection_info); 1849 dump_config(&options); 1850 } 1851 1852 /* Configuration looks good, so exit if in test mode. */ 1853 if (test_flag) 1854 exit(0); 1855 1856 /* 1857 * Clear out any supplemental groups we may have inherited. This 1858 * prevents inadvertent creation of files with bad modes (in the 1859 * portable version at least, it's certainly possible for PAM 1860 * to create a file, and we can't control the code in every 1861 * module which might be used). 1862 */ 1863 if (setgroups(0, NULL) < 0) 1864 debug("setgroups() failed: %.200s", strerror(errno)); 1865 1866 if (rexec_flag) { 1867 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1868 for (i = 0; i < rexec_argc; i++) { 1869 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1870 rexec_argv[i] = saved_argv[i]; 1871 } 1872 rexec_argv[rexec_argc] = "-R"; 1873 rexec_argv[rexec_argc + 1] = NULL; 1874 } 1875 1876 /* Ensure that umask disallows at least group and world write */ 1877 new_umask = umask(0077) | 0022; 1878 (void) umask(new_umask); 1879 1880 /* Initialize the log (it is reinitialized below in case we forked). */ 1881 if (debug_flag && (!inetd_flag || rexeced_flag)) 1882 log_stderr = 1; 1883 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1884 1885 /* 1886 * If not in debugging mode, and not started from inetd, disconnect 1887 * from the controlling terminal, and fork. The original process 1888 * exits. 1889 */ 1890 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1891#ifdef TIOCNOTTY 1892 int fd; 1893#endif /* TIOCNOTTY */ 1894 if (daemon(0, 0) < 0) 1895 fatal("daemon() failed: %.200s", strerror(errno)); 1896 1897 /* Disconnect from the controlling tty. */ 1898#ifdef TIOCNOTTY 1899 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1900 if (fd >= 0) { 1901 (void) ioctl(fd, TIOCNOTTY, NULL); 1902 close(fd); 1903 } 1904#endif /* TIOCNOTTY */ 1905 } 1906 /* Reinitialize the log (because of the fork above). */ 1907 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1908 1909 /* Avoid killing the process in high-pressure swapping environments. */ 1910 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 1911 debug("madvise(): %.200s", strerror(errno)); 1912 1913 /* Chdir to the root directory so that the current disk can be 1914 unmounted if desired. */ 1915 if (chdir("/") == -1) 1916 error("chdir(\"/\"): %s", strerror(errno)); 1917 1918 /* ignore SIGPIPE */ 1919 signal(SIGPIPE, SIG_IGN); 1920 1921 /* Get a connection, either from inetd or a listening TCP socket */ 1922 if (inetd_flag) { 1923 server_accept_inetd(&sock_in, &sock_out); 1924 } else { 1925 platform_pre_listen(); 1926 server_listen(); 1927 1928 if (options.protocol & SSH_PROTO_1) 1929 generate_ephemeral_server_key(); 1930 1931 signal(SIGHUP, sighup_handler); 1932 signal(SIGCHLD, main_sigchld_handler); 1933 signal(SIGTERM, sigterm_handler); 1934 signal(SIGQUIT, sigterm_handler); 1935 1936 /* 1937 * Write out the pid file after the sigterm handler 1938 * is setup and the listen sockets are bound 1939 */ 1940 if (!debug_flag) { 1941 FILE *f = fopen(options.pid_file, "w"); 1942 1943 if (f == NULL) { 1944 error("Couldn't create pid file \"%s\": %s", 1945 options.pid_file, strerror(errno)); 1946 } else { 1947 fprintf(f, "%ld\n", (long) getpid()); 1948 fclose(f); 1949 } 1950 } 1951 1952 /* Accept a connection and return in a forked child */ 1953 server_accept_loop(&sock_in, &sock_out, 1954 &newsock, config_s); 1955 } 1956 1957 /* This is the child processing a new connection. */ 1958 setproctitle("%s", "[accepted]"); 1959 1960 /* 1961 * Create a new session and process group since the 4.4BSD 1962 * setlogin() affects the entire process group. We don't 1963 * want the child to be able to affect the parent. 1964 */ 1965#if !defined(SSHD_ACQUIRES_CTTY) 1966 /* 1967 * If setsid is called, on some platforms sshd will later acquire a 1968 * controlling terminal which will result in "could not set 1969 * controlling tty" errors. 1970 */ 1971 if (!debug_flag && !inetd_flag && setsid() < 0) 1972 error("setsid: %.100s", strerror(errno)); 1973#endif 1974 1975 if (rexec_flag) { 1976 int fd; 1977 1978 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1979 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1980 dup2(newsock, STDIN_FILENO); 1981 dup2(STDIN_FILENO, STDOUT_FILENO); 1982 if (startup_pipe == -1) 1983 close(REEXEC_STARTUP_PIPE_FD); 1984 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1985 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1986 close(startup_pipe); 1987 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1988 } 1989 1990 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1991 close(config_s[1]); 1992 1993 execv(rexec_argv[0], rexec_argv); 1994 1995 /* Reexec has failed, fall back and continue */ 1996 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1997 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1998 log_init(__progname, options.log_level, 1999 options.log_facility, log_stderr); 2000 2001 /* Clean up fds */ 2002 close(REEXEC_CONFIG_PASS_FD); 2003 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2004 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 2005 dup2(fd, STDIN_FILENO); 2006 dup2(fd, STDOUT_FILENO); 2007 if (fd > STDERR_FILENO) 2008 close(fd); 2009 } 2010 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2011 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2012 } 2013 2014 /* Executed child processes don't need these. */ 2015 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2016 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2017 2018 /* 2019 * Disable the key regeneration alarm. We will not regenerate the 2020 * key since we are no longer in a position to give it to anyone. We 2021 * will not restart on SIGHUP since it no longer makes sense. 2022 */ 2023 alarm(0); 2024 signal(SIGALRM, SIG_DFL); 2025 signal(SIGHUP, SIG_DFL); 2026 signal(SIGTERM, SIG_DFL); 2027 signal(SIGQUIT, SIG_DFL); 2028 signal(SIGCHLD, SIG_DFL); 2029 signal(SIGINT, SIG_DFL); 2030 2031#ifdef __FreeBSD__ 2032 /* 2033 * Initialize the resolver. This may not happen automatically 2034 * before privsep chroot(). 2035 */ 2036 if ((_res.options & RES_INIT) == 0) { 2037 debug("res_init()"); 2038 res_init(); 2039 } 2040#ifdef GSSAPI 2041 /* 2042 * Force GSS-API to parse its configuration and load any 2043 * mechanism plugins. 2044 */ 2045 { 2046 gss_OID_set mechs; 2047 OM_uint32 minor_status; 2048 gss_indicate_mechs(&minor_status, &mechs); 2049 gss_release_oid_set(&minor_status, &mechs); 2050 } 2051#endif 2052#endif 2053 2054 /* 2055 * Register our connection. This turns encryption off because we do 2056 * not have a key. 2057 */ 2058 packet_set_connection(sock_in, sock_out); 2059 packet_set_server(); 2060 2061 /* Set SO_KEEPALIVE if requested. */ 2062 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 2063 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 2064 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2065 2066 if ((remote_port = get_remote_port()) < 0) { 2067 debug("get_remote_port failed"); 2068 cleanup_exit(255); 2069 } 2070 2071 /* 2072 * We use get_canonical_hostname with usedns = 0 instead of 2073 * get_remote_ipaddr here so IP options will be checked. 2074 */ 2075 (void) get_canonical_hostname(0); 2076 /* 2077 * The rest of the code depends on the fact that 2078 * get_remote_ipaddr() caches the remote ip, even if 2079 * the socket goes away. 2080 */ 2081 remote_ip = get_remote_ipaddr(); 2082 2083#ifdef SSH_AUDIT_EVENTS 2084 audit_connection_from(remote_ip, remote_port); 2085#endif 2086#ifdef LIBWRAP 2087 allow_severity = options.log_facility|LOG_INFO; 2088 deny_severity = options.log_facility|LOG_WARNING; 2089 /* Check whether logins are denied from this host. */ 2090 if (packet_connection_is_on_socket()) { 2091 struct request_info req; 2092 2093 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 2094 fromhost(&req); 2095 2096 if (!hosts_access(&req)) { 2097 debug("Connection refused by tcp wrapper"); 2098 refuse(&req); 2099 /* NOTREACHED */ 2100 fatal("libwrap refuse returns"); 2101 } 2102 } 2103#endif /* LIBWRAP */ 2104 2105 /* Log the connection. */ 2106 verbose("Connection from %s port %d on %s port %d", 2107 remote_ip, remote_port, 2108 get_local_ipaddr(sock_in), get_local_port()); 2109 2110 /* 2111 * We don't want to listen forever unless the other side 2112 * successfully authenticates itself. So we set up an alarm which is 2113 * cleared after successful authentication. A limit of zero 2114 * indicates no limit. Note that we don't set the alarm in debugging 2115 * mode; it is just annoying to have the server exit just when you 2116 * are about to discover the bug. 2117 */ 2118 signal(SIGALRM, grace_alarm_handler); 2119 if (!debug_flag) 2120 alarm(options.login_grace_time); 2121 2122 sshd_exchange_identification(sock_in, sock_out); 2123 2124 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 2125 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 2126 generate_ephemeral_server_key(); 2127 2128 packet_set_nonblocking(); 2129 2130 /* allocate authentication context */ 2131 authctxt = xcalloc(1, sizeof(*authctxt)); 2132 2133 authctxt->loginmsg = &loginmsg; 2134 2135 /* XXX global for cleanup, access from other modules */ 2136 the_authctxt = authctxt; 2137 2138 /* prepare buffer to collect messages to display to user after login */ 2139 buffer_init(&loginmsg); 2140 auth_debug_reset(); 2141 2142 if (use_privsep) { 2143 if (privsep_preauth(authctxt) == 1) 2144 goto authenticated; 2145 } else if (compat20 && have_agent) 2146 auth_conn = ssh_get_authentication_connection(); 2147 2148 /* perform the key exchange */ 2149 /* authenticate user and start session */ 2150 if (compat20) { 2151 do_ssh2_kex(); 2152 do_authentication2(authctxt); 2153 } else { 2154 do_ssh1_kex(); 2155 do_authentication(authctxt); 2156 } 2157 /* 2158 * If we use privilege separation, the unprivileged child transfers 2159 * the current keystate and exits 2160 */ 2161 if (use_privsep) { 2162 mm_send_keystate(pmonitor); 2163 exit(0); 2164 } 2165 2166 authenticated: 2167 /* 2168 * Cancel the alarm we set to limit the time taken for 2169 * authentication. 2170 */ 2171 alarm(0); 2172 signal(SIGALRM, SIG_DFL); 2173 authctxt->authenticated = 1; 2174 if (startup_pipe != -1) { 2175 close(startup_pipe); 2176 startup_pipe = -1; 2177 } 2178 2179#ifdef SSH_AUDIT_EVENTS 2180 audit_event(SSH_AUTH_SUCCESS); 2181#endif 2182 2183#ifdef GSSAPI 2184 if (options.gss_authentication) { 2185 temporarily_use_uid(authctxt->pw); 2186 ssh_gssapi_storecreds(); 2187 restore_uid(); 2188 } 2189#endif 2190#ifdef USE_PAM 2191 if (options.use_pam) { 2192 do_pam_setcred(1); 2193 do_pam_session(); 2194 } 2195#endif 2196 2197 /* 2198 * In privilege separation, we fork another child and prepare 2199 * file descriptor passing. 2200 */ 2201 if (use_privsep) { 2202 privsep_postauth(authctxt); 2203 /* the monitor process [priv] will not return */ 2204 if (!compat20) 2205 destroy_sensitive_data(); 2206 } 2207 2208 packet_set_timeout(options.client_alive_interval, 2209 options.client_alive_count_max); 2210 2211 /* Start session. */ 2212 do_authenticated(authctxt); 2213 2214 /* The connection has been terminated. */ 2215 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 2216 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 2217 verbose("Transferred: sent %llu, received %llu bytes", 2218 (unsigned long long)obytes, (unsigned long long)ibytes); 2219 2220 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2221 2222#ifdef USE_PAM 2223 if (options.use_pam) 2224 finish_pam(); 2225#endif /* USE_PAM */ 2226 2227#ifdef SSH_AUDIT_EVENTS 2228 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2229#endif 2230 2231 packet_close(); 2232 2233 if (use_privsep) 2234 mm_terminate(); 2235 2236 exit(0); 2237} 2238 2239/* 2240 * Decrypt session_key_int using our private server key and private host key 2241 * (key with larger modulus first). 2242 */ 2243int 2244ssh1_session_key(BIGNUM *session_key_int) 2245{ 2246 int rsafail = 0; 2247 2248 if (BN_cmp(sensitive_data.server_key->rsa->n, 2249 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2250 /* Server key has bigger modulus. */ 2251 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2252 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2253 SSH_KEY_BITS_RESERVED) { 2254 fatal("do_connection: %s: " 2255 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2256 get_remote_ipaddr(), 2257 BN_num_bits(sensitive_data.server_key->rsa->n), 2258 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2259 SSH_KEY_BITS_RESERVED); 2260 } 2261 if (rsa_private_decrypt(session_key_int, session_key_int, 2262 sensitive_data.server_key->rsa) <= 0) 2263 rsafail++; 2264 if (rsa_private_decrypt(session_key_int, session_key_int, 2265 sensitive_data.ssh1_host_key->rsa) <= 0) 2266 rsafail++; 2267 } else { 2268 /* Host key has bigger modulus (or they are equal). */ 2269 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2270 BN_num_bits(sensitive_data.server_key->rsa->n) + 2271 SSH_KEY_BITS_RESERVED) { 2272 fatal("do_connection: %s: " 2273 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2274 get_remote_ipaddr(), 2275 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2276 BN_num_bits(sensitive_data.server_key->rsa->n), 2277 SSH_KEY_BITS_RESERVED); 2278 } 2279 if (rsa_private_decrypt(session_key_int, session_key_int, 2280 sensitive_data.ssh1_host_key->rsa) < 0) 2281 rsafail++; 2282 if (rsa_private_decrypt(session_key_int, session_key_int, 2283 sensitive_data.server_key->rsa) < 0) 2284 rsafail++; 2285 } 2286 return (rsafail); 2287} 2288/* 2289 * SSH1 key exchange 2290 */ 2291static void 2292do_ssh1_kex(void) 2293{ 2294 int i, len; 2295 int rsafail = 0; 2296 BIGNUM *session_key_int; 2297 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2298 u_char cookie[8]; 2299 u_int cipher_type, auth_mask, protocol_flags; 2300 2301 /* 2302 * Generate check bytes that the client must send back in the user 2303 * packet in order for it to be accepted; this is used to defy ip 2304 * spoofing attacks. Note that this only works against somebody 2305 * doing IP spoofing from a remote machine; any machine on the local 2306 * network can still see outgoing packets and catch the random 2307 * cookie. This only affects rhosts authentication, and this is one 2308 * of the reasons why it is inherently insecure. 2309 */ 2310 arc4random_buf(cookie, sizeof(cookie)); 2311 2312 /* 2313 * Send our public key. We include in the packet 64 bits of random 2314 * data that must be matched in the reply in order to prevent IP 2315 * spoofing. 2316 */ 2317 packet_start(SSH_SMSG_PUBLIC_KEY); 2318 for (i = 0; i < 8; i++) 2319 packet_put_char(cookie[i]); 2320 2321 /* Store our public server RSA key. */ 2322 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2323 packet_put_bignum(sensitive_data.server_key->rsa->e); 2324 packet_put_bignum(sensitive_data.server_key->rsa->n); 2325 2326 /* Store our public host RSA key. */ 2327 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2328 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2329 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2330 2331 /* Put protocol flags. */ 2332 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2333 2334 /* Declare which ciphers we support. */ 2335 packet_put_int(cipher_mask_ssh1(0)); 2336 2337 /* Declare supported authentication types. */ 2338 auth_mask = 0; 2339 if (options.rhosts_rsa_authentication) 2340 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2341 if (options.rsa_authentication) 2342 auth_mask |= 1 << SSH_AUTH_RSA; 2343 if (options.challenge_response_authentication == 1) 2344 auth_mask |= 1 << SSH_AUTH_TIS; 2345 if (options.password_authentication) 2346 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2347 packet_put_int(auth_mask); 2348 2349 /* Send the packet and wait for it to be sent. */ 2350 packet_send(); 2351 packet_write_wait(); 2352 2353 debug("Sent %d bit server key and %d bit host key.", 2354 BN_num_bits(sensitive_data.server_key->rsa->n), 2355 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2356 2357 /* Read clients reply (cipher type and session key). */ 2358 packet_read_expect(SSH_CMSG_SESSION_KEY); 2359 2360 /* Get cipher type and check whether we accept this. */ 2361 cipher_type = packet_get_char(); 2362 2363 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2364 packet_disconnect("Warning: client selects unsupported cipher."); 2365 2366 /* Get check bytes from the packet. These must match those we 2367 sent earlier with the public key packet. */ 2368 for (i = 0; i < 8; i++) 2369 if (cookie[i] != packet_get_char()) 2370 packet_disconnect("IP Spoofing check bytes do not match."); 2371 2372 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2373 2374 /* Get the encrypted integer. */ 2375 if ((session_key_int = BN_new()) == NULL) 2376 fatal("do_ssh1_kex: BN_new failed"); 2377 packet_get_bignum(session_key_int); 2378 2379 protocol_flags = packet_get_int(); 2380 packet_set_protocol_flags(protocol_flags); 2381 packet_check_eom(); 2382 2383 /* Decrypt session_key_int using host/server keys */ 2384 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2385 2386 /* 2387 * Extract session key from the decrypted integer. The key is in the 2388 * least significant 256 bits of the integer; the first byte of the 2389 * key is in the highest bits. 2390 */ 2391 if (!rsafail) { 2392 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2393 len = BN_num_bytes(session_key_int); 2394 if (len < 0 || (u_int)len > sizeof(session_key)) { 2395 error("do_ssh1_kex: bad session key len from %s: " 2396 "session_key_int %d > sizeof(session_key) %lu", 2397 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2398 rsafail++; 2399 } else { 2400 explicit_bzero(session_key, sizeof(session_key)); 2401 BN_bn2bin(session_key_int, 2402 session_key + sizeof(session_key) - len); 2403 2404 derive_ssh1_session_id( 2405 sensitive_data.ssh1_host_key->rsa->n, 2406 sensitive_data.server_key->rsa->n, 2407 cookie, session_id); 2408 /* 2409 * Xor the first 16 bytes of the session key with the 2410 * session id. 2411 */ 2412 for (i = 0; i < 16; i++) 2413 session_key[i] ^= session_id[i]; 2414 } 2415 } 2416 if (rsafail) { 2417 int bytes = BN_num_bytes(session_key_int); 2418 u_char *buf = xmalloc(bytes); 2419 struct ssh_digest_ctx *md; 2420 2421 logit("do_connection: generating a fake encryption key"); 2422 BN_bn2bin(session_key_int, buf); 2423 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || 2424 ssh_digest_update(md, buf, bytes) < 0 || 2425 ssh_digest_update(md, sensitive_data.ssh1_cookie, 2426 SSH_SESSION_KEY_LENGTH) < 0 || 2427 ssh_digest_final(md, session_key, sizeof(session_key)) < 0) 2428 fatal("%s: md5 failed", __func__); 2429 ssh_digest_free(md); 2430 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || 2431 ssh_digest_update(md, session_key, 16) < 0 || 2432 ssh_digest_update(md, sensitive_data.ssh1_cookie, 2433 SSH_SESSION_KEY_LENGTH) < 0 || 2434 ssh_digest_final(md, session_key + 16, 2435 sizeof(session_key) - 16) < 0) 2436 fatal("%s: md5 failed", __func__); 2437 ssh_digest_free(md); 2438 explicit_bzero(buf, bytes); 2439 free(buf); 2440 for (i = 0; i < 16; i++) 2441 session_id[i] = session_key[i] ^ session_key[i + 16]; 2442 } 2443 /* Destroy the private and public keys. No longer. */ 2444 destroy_sensitive_data(); 2445 2446 if (use_privsep) 2447 mm_ssh1_session_id(session_id); 2448 2449 /* Destroy the decrypted integer. It is no longer needed. */ 2450 BN_clear_free(session_key_int); 2451 2452 /* Set the session key. From this on all communications will be encrypted. */ 2453 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2454 2455 /* Destroy our copy of the session key. It is no longer needed. */ 2456 explicit_bzero(session_key, sizeof(session_key)); 2457 2458 debug("Received session key; encryption turned on."); 2459 2460 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2461 packet_start(SSH_SMSG_SUCCESS); 2462 packet_send(); 2463 packet_write_wait(); 2464} 2465 2466void 2467sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, u_int *slen, 2468 u_char *data, u_int dlen) 2469{ 2470 if (privkey) { 2471 if (PRIVSEP(key_sign(privkey, signature, slen, data, dlen) < 0)) 2472 fatal("%s: key_sign failed", __func__); 2473 } else if (use_privsep) { 2474 if (mm_key_sign(pubkey, signature, slen, data, dlen) < 0) 2475 fatal("%s: pubkey_sign failed", __func__); 2476 } else { 2477 if (ssh_agent_sign(auth_conn, pubkey, signature, slen, data, 2478 dlen)) 2479 fatal("%s: ssh_agent_sign failed", __func__); 2480 } 2481} 2482 2483/* 2484 * SSH2 key exchange: diffie-hellman-group1-sha1 2485 */ 2486static void 2487do_ssh2_kex(void) 2488{ 2489 Kex *kex; 2490 2491 if (options.ciphers != NULL) { 2492 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2493 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2494 } 2495 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2496 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2497 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2498 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2499 2500 if (options.macs != NULL) { 2501 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2502 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2503 } 2504 if (options.compression == COMP_NONE) { 2505 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2506 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2507 } else if (options.compression == COMP_DELAYED) { 2508 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2509 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2510 } 2511 if (options.kex_algorithms != NULL) 2512 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 2513 2514 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2515 myproposal[PROPOSAL_KEX_ALGS]); 2516 2517 if (options.rekey_limit || options.rekey_interval) 2518 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 2519 (time_t)options.rekey_interval); 2520 2521 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2522 list_hostkey_types()); 2523 2524 /* start key exchange */ 2525 kex = kex_setup(myproposal); 2526 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2527 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2528 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2529 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2530 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2531 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2532 kex->server = 1; 2533 kex->client_version_string=client_version_string; 2534 kex->server_version_string=server_version_string; 2535 kex->load_host_public_key=&get_hostkey_public_by_type; 2536 kex->load_host_private_key=&get_hostkey_private_by_type; 2537 kex->host_key_index=&get_hostkey_index; 2538 kex->sign = sshd_hostkey_sign; 2539 2540 xxx_kex = kex; 2541 2542 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2543 2544 session_id2 = kex->session_id; 2545 session_id2_len = kex->session_id_len; 2546 2547#ifdef DEBUG_KEXDH 2548 /* send 1st encrypted/maced/compressed message */ 2549 packet_start(SSH2_MSG_IGNORE); 2550 packet_put_cstring("markus"); 2551 packet_send(); 2552 packet_write_wait(); 2553#endif 2554 debug("KEX done"); 2555} 2556 2557/* server specific fatal cleanup */ 2558void 2559cleanup_exit(int i) 2560{ 2561 if (the_authctxt) { 2562 do_cleanup(the_authctxt); 2563 if (use_privsep && privsep_is_preauth && pmonitor->m_pid > 1) { 2564 debug("Killing privsep child %d", pmonitor->m_pid); 2565 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2566 errno != ESRCH) 2567 error("%s: kill(%d): %s", __func__, 2568 pmonitor->m_pid, strerror(errno)); 2569 } 2570 } 2571#ifdef SSH_AUDIT_EVENTS 2572 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2573 if (!use_privsep || mm_is_monitor()) 2574 audit_event(SSH_CONNECTION_ABANDON); 2575#endif 2576 _exit(i); 2577} 2578