sshd.c revision 323129
1/* $OpenBSD: sshd.c,v 1.470 2016/05/24 04:43:45 dtucker 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/11/crypto/openssh/sshd.c 323129 2017-09-02 14:25:20Z 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#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 "ssh1.h" 102#include "ssh2.h" 103#include "rsa.h" 104#include "sshpty.h" 105#include "packet.h" 106#include "log.h" 107#include "buffer.h" 108#include "misc.h" 109#include "match.h" 110#include "servconf.h" 111#include "uidswap.h" 112#include "compat.h" 113#include "cipher.h" 114#include "digest.h" 115#include "key.h" 116#include "kex.h" 117#include "myproposal.h" 118#include "authfile.h" 119#include "pathnames.h" 120#include "atomicio.h" 121#include "canohost.h" 122#include "hostfile.h" 123#include "auth.h" 124#include "authfd.h" 125#include "msg.h" 126#include "dispatch.h" 127#include "channels.h" 128#include "session.h" 129#include "monitor_mm.h" 130#include "monitor.h" 131#ifdef GSSAPI 132#include "ssh-gss.h" 133#endif 134#include "monitor_wrap.h" 135#include "ssh-sandbox.h" 136#include "version.h" 137#include "ssherr.h" 138#include "blacklist_client.h" 139 140#ifdef LIBWRAP 141#include <tcpd.h> 142#include <syslog.h> 143int allow_severity; 144int deny_severity; 145#endif /* LIBWRAP */ 146 147#ifndef O_NOCTTY 148#define O_NOCTTY 0 149#endif 150 151/* Re-exec fds */ 152#define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 153#define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 154#define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 155#define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 156 157extern char *__progname; 158 159/* Server configuration options. */ 160ServerOptions options; 161 162/* Name of the server configuration file. */ 163char *config_file_name = _PATH_SERVER_CONFIG_FILE; 164 165/* 166 * Debug mode flag. This can be set on the command line. If debug 167 * mode is enabled, extra debugging output will be sent to the system 168 * log, the daemon will not go to background, and will exit after processing 169 * the first connection. 170 */ 171int debug_flag = 0; 172 173/* Flag indicating that the daemon should only test the configuration and keys. */ 174int test_flag = 0; 175 176/* Flag indicating that the daemon is being started from inetd. */ 177int inetd_flag = 0; 178 179/* Flag indicating that sshd should not detach and become a daemon. */ 180int no_daemon_flag = 0; 181 182/* debug goes to stderr unless inetd_flag is set */ 183int log_stderr = 0; 184 185/* Saved arguments to main(). */ 186char **saved_argv; 187int saved_argc; 188 189/* re-exec */ 190int rexeced_flag = 0; 191int rexec_flag = 1; 192int rexec_argc = 0; 193char **rexec_argv; 194 195/* 196 * The sockets that the server is listening; this is used in the SIGHUP 197 * signal handler. 198 */ 199#define MAX_LISTEN_SOCKS 16 200int listen_socks[MAX_LISTEN_SOCKS]; 201int num_listen_socks = 0; 202 203/* 204 * the client's version string, passed by sshd2 in compat mode. if != NULL, 205 * sshd will skip the version-number exchange 206 */ 207char *client_version_string = NULL; 208char *server_version_string = NULL; 209 210/* Daemon's agent connection */ 211int auth_sock = -1; 212int have_agent = 0; 213 214/* 215 * Any really sensitive data in the application is contained in this 216 * structure. The idea is that this structure could be locked into memory so 217 * that the pages do not get written into swap. However, there are some 218 * problems. The private key contains BIGNUMs, and we do not (in principle) 219 * have access to the internals of them, and locking just the structure is 220 * not very useful. Currently, memory locking is not implemented. 221 */ 222struct { 223 Key *server_key; /* ephemeral server key */ 224 Key *ssh1_host_key; /* ssh1 host key */ 225 Key **host_keys; /* all private host keys */ 226 Key **host_pubkeys; /* all public host keys */ 227 Key **host_certificates; /* all public host certificates */ 228 int have_ssh1_key; 229 int have_ssh2_key; 230 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 231} sensitive_data; 232 233/* 234 * Flag indicating whether the RSA server key needs to be regenerated. 235 * Is set in the SIGALRM handler and cleared when the key is regenerated. 236 */ 237static volatile sig_atomic_t key_do_regen = 0; 238 239/* This is set to true when a signal is received. */ 240static volatile sig_atomic_t received_sighup = 0; 241static volatile sig_atomic_t received_sigterm = 0; 242 243/* session identifier, used by RSA-auth */ 244u_char session_id[16]; 245 246/* same for ssh2 */ 247u_char *session_id2 = NULL; 248u_int session_id2_len = 0; 249 250/* record remote hostname or ip */ 251u_int utmp_len = HOST_NAME_MAX+1; 252 253/* options.max_startup sized array of fd ints */ 254int *startup_pipes = NULL; 255int startup_pipe; /* in child */ 256 257/* variables used for privilege separation */ 258int use_privsep = -1; 259struct monitor *pmonitor = NULL; 260int privsep_is_preauth = 1; 261 262/* global authentication context */ 263Authctxt *the_authctxt = NULL; 264 265/* sshd_config buffer */ 266Buffer cfg; 267 268/* message to be displayed after login */ 269Buffer loginmsg; 270 271/* Unprivileged user */ 272struct passwd *privsep_pw = NULL; 273 274/* Prototypes for various functions defined later in this file. */ 275void destroy_sensitive_data(void); 276void demote_sensitive_data(void); 277 278#ifdef WITH_SSH1 279static void do_ssh1_kex(void); 280#endif 281static void do_ssh2_kex(void); 282 283/* 284 * Close all listening sockets 285 */ 286static void 287close_listen_socks(void) 288{ 289 int i; 290 291 for (i = 0; i < num_listen_socks; i++) 292 close(listen_socks[i]); 293 num_listen_socks = -1; 294} 295 296static void 297close_startup_pipes(void) 298{ 299 int i; 300 301 if (startup_pipes) 302 for (i = 0; i < options.max_startups; i++) 303 if (startup_pipes[i] != -1) 304 close(startup_pipes[i]); 305} 306 307/* 308 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 309 * the effect is to reread the configuration file (and to regenerate 310 * the server key). 311 */ 312 313/*ARGSUSED*/ 314static void 315sighup_handler(int sig) 316{ 317 int save_errno = errno; 318 319 received_sighup = 1; 320 signal(SIGHUP, sighup_handler); 321 errno = save_errno; 322} 323 324/* 325 * Called from the main program after receiving SIGHUP. 326 * Restarts the server. 327 */ 328static void 329sighup_restart(void) 330{ 331 logit("Received SIGHUP; restarting."); 332 platform_pre_restart(); 333 close_listen_socks(); 334 close_startup_pipes(); 335 alarm(0); /* alarm timer persists across exec */ 336 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 337 execv(saved_argv[0], saved_argv); 338 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 339 strerror(errno)); 340 exit(1); 341} 342 343/* 344 * Generic signal handler for terminating signals in the master daemon. 345 */ 346/*ARGSUSED*/ 347static void 348sigterm_handler(int sig) 349{ 350 received_sigterm = sig; 351} 352 353/* 354 * SIGCHLD handler. This is called whenever a child dies. This will then 355 * reap any zombies left by exited children. 356 */ 357/*ARGSUSED*/ 358static void 359main_sigchld_handler(int sig) 360{ 361 int save_errno = errno; 362 pid_t pid; 363 int status; 364 365 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 366 (pid < 0 && errno == EINTR)) 367 ; 368 369 signal(SIGCHLD, main_sigchld_handler); 370 errno = save_errno; 371} 372 373/* 374 * Signal handler for the alarm after the login grace period has expired. 375 */ 376/*ARGSUSED*/ 377static void 378grace_alarm_handler(int sig) 379{ 380 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 381 kill(pmonitor->m_pid, SIGALRM); 382 383 /* 384 * Try to kill any processes that we have spawned, E.g. authorized 385 * keys command helpers. 386 */ 387 if (getpgid(0) == getpid()) { 388 signal(SIGTERM, SIG_IGN); 389 kill(0, SIGTERM); 390 } 391 392 BLACKLIST_NOTIFY(BLACKLIST_AUTH_FAIL, "ssh"); 393 394 /* Log error and exit. */ 395 sigdie("Timeout before authentication for %s port %d", 396 ssh_remote_ipaddr(active_state), ssh_remote_port(active_state)); 397} 398 399/* 400 * Signal handler for the key regeneration alarm. Note that this 401 * alarm only occurs in the daemon waiting for connections, and it does not 402 * do anything with the private key or random state before forking. 403 * Thus there should be no concurrency control/asynchronous execution 404 * problems. 405 */ 406static void 407generate_ephemeral_server_key(void) 408{ 409 verbose("Generating %s%d bit RSA key.", 410 sensitive_data.server_key ? "new " : "", options.server_key_bits); 411 if (sensitive_data.server_key != NULL) 412 key_free(sensitive_data.server_key); 413 sensitive_data.server_key = key_generate(KEY_RSA1, 414 options.server_key_bits); 415 verbose("RSA key generation complete."); 416 417 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 418} 419 420/*ARGSUSED*/ 421static void 422key_regeneration_alarm(int sig) 423{ 424 int save_errno = errno; 425 426 signal(SIGALRM, SIG_DFL); 427 errno = save_errno; 428 key_do_regen = 1; 429} 430 431static void 432sshd_exchange_identification(struct ssh *ssh, int sock_in, int sock_out) 433{ 434 u_int i; 435 int mismatch; 436 int remote_major, remote_minor; 437 int major, minor; 438 char *s, *newline = "\n"; 439 char buf[256]; /* Must not be larger than remote_version. */ 440 char remote_version[256]; /* Must be at least as big as buf. */ 441 442 if ((options.protocol & SSH_PROTO_1) && 443 (options.protocol & SSH_PROTO_2)) { 444 major = PROTOCOL_MAJOR_1; 445 minor = 99; 446 } else if (options.protocol & SSH_PROTO_2) { 447 major = PROTOCOL_MAJOR_2; 448 minor = PROTOCOL_MINOR_2; 449 newline = "\r\n"; 450 } else { 451 major = PROTOCOL_MAJOR_1; 452 minor = PROTOCOL_MINOR_1; 453 } 454 455 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s", 456 major, minor, SSH_VERSION, 457 *options.version_addendum == '\0' ? "" : " ", 458 options.version_addendum, newline); 459 460 /* Send our protocol version identification. */ 461 if (atomicio(vwrite, sock_out, server_version_string, 462 strlen(server_version_string)) 463 != strlen(server_version_string)) { 464 logit("Could not write ident string to %s port %d", 465 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 466 cleanup_exit(255); 467 } 468 469 /* Read other sides version identification. */ 470 memset(buf, 0, sizeof(buf)); 471 for (i = 0; i < sizeof(buf) - 1; i++) { 472 if (atomicio(read, sock_in, &buf[i], 1) != 1) { 473 logit("Did not receive identification string " 474 "from %s port %d", 475 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 476 cleanup_exit(255); 477 } 478 if (buf[i] == '\r') { 479 buf[i] = 0; 480 /* Kludge for F-Secure Macintosh < 1.0.2 */ 481 if (i == 12 && 482 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 483 break; 484 continue; 485 } 486 if (buf[i] == '\n') { 487 buf[i] = 0; 488 break; 489 } 490 } 491 buf[sizeof(buf) - 1] = 0; 492 client_version_string = xstrdup(buf); 493 494 /* 495 * Check that the versions match. In future this might accept 496 * several versions and set appropriate flags to handle them. 497 */ 498 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 499 &remote_major, &remote_minor, remote_version) != 3) { 500 s = "Protocol mismatch.\n"; 501 (void) atomicio(vwrite, sock_out, s, strlen(s)); 502 logit("Bad protocol version identification '%.100s' " 503 "from %s port %d", client_version_string, 504 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 505 close(sock_in); 506 close(sock_out); 507 cleanup_exit(255); 508 } 509 debug("Client protocol version %d.%d; client software version %.100s", 510 remote_major, remote_minor, remote_version); 511 512 ssh->compat = compat_datafellows(remote_version); 513 514 if ((ssh->compat & SSH_BUG_PROBE) != 0) { 515 logit("probed from %s port %d with %s. Don't panic.", 516 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 517 client_version_string); 518 cleanup_exit(255); 519 } 520 if ((ssh->compat & SSH_BUG_SCANNER) != 0) { 521 logit("scanned from %s port %d with %s. Don't panic.", 522 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 523 client_version_string); 524 cleanup_exit(255); 525 } 526 if ((ssh->compat & SSH_BUG_RSASIGMD5) != 0) { 527 logit("Client version \"%.100s\" uses unsafe RSA signature " 528 "scheme; disabling use of RSA keys", remote_version); 529 } 530 if ((ssh->compat & SSH_BUG_DERIVEKEY) != 0) { 531 fatal("Client version \"%.100s\" uses unsafe key agreement; " 532 "refusing connection", remote_version); 533 } 534 535 mismatch = 0; 536 switch (remote_major) { 537 case 1: 538 if (remote_minor == 99) { 539 if (options.protocol & SSH_PROTO_2) 540 enable_compat20(); 541 else 542 mismatch = 1; 543 break; 544 } 545 if (!(options.protocol & SSH_PROTO_1)) { 546 mismatch = 1; 547 break; 548 } 549 if (remote_minor < 3) { 550 packet_disconnect("Your ssh version is too old and " 551 "is no longer supported. Please install a newer version."); 552 } else if (remote_minor == 3) { 553 /* note that this disables agent-forwarding */ 554 enable_compat13(); 555 } 556 break; 557 case 2: 558 if (options.protocol & SSH_PROTO_2) { 559 enable_compat20(); 560 break; 561 } 562 /* FALLTHROUGH */ 563 default: 564 mismatch = 1; 565 break; 566 } 567 chop(server_version_string); 568 debug("Local version string %.200s", server_version_string); 569 570 if (mismatch) { 571 s = "Protocol major versions differ.\n"; 572 (void) atomicio(vwrite, sock_out, s, strlen(s)); 573 close(sock_in); 574 close(sock_out); 575 logit("Protocol major versions differ for %s port %d: " 576 "%.200s vs. %.200s", 577 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 578 server_version_string, client_version_string); 579 cleanup_exit(255); 580 } 581} 582 583/* Destroy the host and server keys. They will no longer be needed. */ 584void 585destroy_sensitive_data(void) 586{ 587 int i; 588 589 if (sensitive_data.server_key) { 590 key_free(sensitive_data.server_key); 591 sensitive_data.server_key = NULL; 592 } 593 for (i = 0; i < options.num_host_key_files; i++) { 594 if (sensitive_data.host_keys[i]) { 595 key_free(sensitive_data.host_keys[i]); 596 sensitive_data.host_keys[i] = NULL; 597 } 598 if (sensitive_data.host_certificates[i]) { 599 key_free(sensitive_data.host_certificates[i]); 600 sensitive_data.host_certificates[i] = NULL; 601 } 602 } 603 sensitive_data.ssh1_host_key = NULL; 604 explicit_bzero(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 605} 606 607/* Demote private to public keys for network child */ 608void 609demote_sensitive_data(void) 610{ 611 Key *tmp; 612 int i; 613 614 if (sensitive_data.server_key) { 615 tmp = key_demote(sensitive_data.server_key); 616 key_free(sensitive_data.server_key); 617 sensitive_data.server_key = tmp; 618 } 619 620 for (i = 0; i < options.num_host_key_files; i++) { 621 if (sensitive_data.host_keys[i]) { 622 tmp = key_demote(sensitive_data.host_keys[i]); 623 key_free(sensitive_data.host_keys[i]); 624 sensitive_data.host_keys[i] = tmp; 625 if (tmp->type == KEY_RSA1) 626 sensitive_data.ssh1_host_key = tmp; 627 } 628 /* Certs do not need demotion */ 629 } 630 631 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 632} 633 634static void 635privsep_preauth_child(void) 636{ 637 u_int32_t rnd[256]; 638 gid_t gidset[1]; 639 640 /* Enable challenge-response authentication for privilege separation */ 641 privsep_challenge_enable(); 642 643#ifdef GSSAPI 644 /* Cache supported mechanism OIDs for later use */ 645 if (options.gss_authentication) 646 ssh_gssapi_prepare_supported_oids(); 647#endif 648 649 arc4random_stir(); 650 arc4random_buf(rnd, sizeof(rnd)); 651#ifdef WITH_OPENSSL 652 RAND_seed(rnd, sizeof(rnd)); 653 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 654 fatal("%s: RAND_bytes failed", __func__); 655#endif 656 explicit_bzero(rnd, sizeof(rnd)); 657 658 /* Demote the private keys to public keys. */ 659 demote_sensitive_data(); 660 661 /* Demote the child */ 662 if (getuid() == 0 || geteuid() == 0) { 663 /* Change our root directory */ 664 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 665 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 666 strerror(errno)); 667 if (chdir("/") == -1) 668 fatal("chdir(\"/\"): %s", strerror(errno)); 669 670 /* Drop our privileges */ 671 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 672 (u_int)privsep_pw->pw_gid); 673 gidset[0] = privsep_pw->pw_gid; 674 if (setgroups(1, gidset) < 0) 675 fatal("setgroups: %.100s", strerror(errno)); 676 permanently_set_uid(privsep_pw); 677 } 678} 679 680static int 681privsep_preauth(Authctxt *authctxt) 682{ 683 int status, r; 684 pid_t pid; 685 struct ssh_sandbox *box = NULL; 686 687 /* Set up unprivileged child process to deal with network data */ 688 pmonitor = monitor_init(); 689 /* Store a pointer to the kex for later rekeying */ 690 pmonitor->m_pkex = &active_state->kex; 691 692 if (use_privsep == PRIVSEP_ON) 693 box = ssh_sandbox_init(pmonitor); 694 pid = fork(); 695 if (pid == -1) { 696 fatal("fork of unprivileged child failed"); 697 } else if (pid != 0) { 698 debug2("Network child is on pid %ld", (long)pid); 699 700 pmonitor->m_pid = pid; 701 if (have_agent) { 702 r = ssh_get_authentication_socket(&auth_sock); 703 if (r != 0) { 704 error("Could not get agent socket: %s", 705 ssh_err(r)); 706 have_agent = 0; 707 } 708 } 709 if (box != NULL) 710 ssh_sandbox_parent_preauth(box, pid); 711 monitor_child_preauth(authctxt, pmonitor); 712 713 /* Sync memory */ 714 monitor_sync(pmonitor); 715 716 /* Wait for the child's exit status */ 717 while (waitpid(pid, &status, 0) < 0) { 718 if (errno == EINTR) 719 continue; 720 pmonitor->m_pid = -1; 721 fatal("%s: waitpid: %s", __func__, strerror(errno)); 722 } 723 privsep_is_preauth = 0; 724 pmonitor->m_pid = -1; 725 if (WIFEXITED(status)) { 726 if (WEXITSTATUS(status) != 0) 727 fatal("%s: preauth child exited with status %d", 728 __func__, WEXITSTATUS(status)); 729 } else if (WIFSIGNALED(status)) 730 fatal("%s: preauth child terminated by signal %d", 731 __func__, WTERMSIG(status)); 732 if (box != NULL) 733 ssh_sandbox_parent_finish(box); 734 return 1; 735 } else { 736 /* child */ 737 close(pmonitor->m_sendfd); 738 close(pmonitor->m_log_recvfd); 739 740 /* Arrange for logging to be sent to the monitor */ 741 set_log_handler(mm_log_handler, pmonitor); 742 743 privsep_preauth_child(); 744 setproctitle("%s", "[net]"); 745 if (box != NULL) 746 ssh_sandbox_child(box); 747 748 return 0; 749 } 750} 751 752static void 753privsep_postauth(Authctxt *authctxt) 754{ 755 u_int32_t rnd[256]; 756 757#ifdef DISABLE_FD_PASSING 758 if (1) { 759#else 760 if (authctxt->pw->pw_uid == 0 || options.use_login) { 761#endif 762 /* File descriptor passing is broken or root login */ 763 use_privsep = 0; 764 goto skip; 765 } 766 767 /* New socket pair */ 768 monitor_reinit(pmonitor); 769 770 pmonitor->m_pid = fork(); 771 if (pmonitor->m_pid == -1) 772 fatal("fork of unprivileged child failed"); 773 else if (pmonitor->m_pid != 0) { 774 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 775 buffer_clear(&loginmsg); 776 monitor_child_postauth(pmonitor); 777 778 /* NEVERREACHED */ 779 exit(0); 780 } 781 782 /* child */ 783 784 close(pmonitor->m_sendfd); 785 pmonitor->m_sendfd = -1; 786 787 /* Demote the private keys to public keys. */ 788 demote_sensitive_data(); 789 790 arc4random_stir(); 791 arc4random_buf(rnd, sizeof(rnd)); 792#ifdef WITH_OPENSSL 793 RAND_seed(rnd, sizeof(rnd)); 794 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 795 fatal("%s: RAND_bytes failed", __func__); 796#endif 797 explicit_bzero(rnd, sizeof(rnd)); 798 799 /* Drop privileges */ 800 do_setusercontext(authctxt->pw); 801 802 skip: 803 /* It is safe now to apply the key state */ 804 monitor_apply_keystate(pmonitor); 805 806 /* 807 * Tell the packet layer that authentication was successful, since 808 * this information is not part of the key state. 809 */ 810 packet_set_authenticated(); 811} 812 813static char * 814list_hostkey_types(void) 815{ 816 Buffer b; 817 const char *p; 818 char *ret; 819 int i; 820 Key *key; 821 822 buffer_init(&b); 823 for (i = 0; i < options.num_host_key_files; i++) { 824 key = sensitive_data.host_keys[i]; 825 if (key == NULL) 826 key = sensitive_data.host_pubkeys[i]; 827 if (key == NULL || key->type == KEY_RSA1) 828 continue; 829 /* Check that the key is accepted in HostkeyAlgorithms */ 830 if (match_pattern_list(sshkey_ssh_name(key), 831 options.hostkeyalgorithms, 0) != 1) { 832 debug3("%s: %s key not permitted by HostkeyAlgorithms", 833 __func__, sshkey_ssh_name(key)); 834 continue; 835 } 836 switch (key->type) { 837 case KEY_RSA: 838 case KEY_DSA: 839 case KEY_ECDSA: 840 case KEY_ED25519: 841 if (buffer_len(&b) > 0) 842 buffer_append(&b, ",", 1); 843 p = key_ssh_name(key); 844 buffer_append(&b, p, strlen(p)); 845 846 /* for RSA we also support SHA2 signatures */ 847 if (key->type == KEY_RSA) { 848 p = ",rsa-sha2-512,rsa-sha2-256"; 849 buffer_append(&b, p, strlen(p)); 850 } 851 break; 852 } 853 /* If the private key has a cert peer, then list that too */ 854 key = sensitive_data.host_certificates[i]; 855 if (key == NULL) 856 continue; 857 switch (key->type) { 858 case KEY_RSA_CERT: 859 case KEY_DSA_CERT: 860 case KEY_ECDSA_CERT: 861 case KEY_ED25519_CERT: 862 if (buffer_len(&b) > 0) 863 buffer_append(&b, ",", 1); 864 p = key_ssh_name(key); 865 buffer_append(&b, p, strlen(p)); 866 break; 867 } 868 } 869 if ((ret = sshbuf_dup_string(&b)) == NULL) 870 fatal("%s: sshbuf_dup_string failed", __func__); 871 buffer_free(&b); 872 debug("list_hostkey_types: %s", ret); 873 return ret; 874} 875 876static Key * 877get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 878{ 879 int i; 880 Key *key; 881 882 for (i = 0; i < options.num_host_key_files; i++) { 883 switch (type) { 884 case KEY_RSA_CERT: 885 case KEY_DSA_CERT: 886 case KEY_ECDSA_CERT: 887 case KEY_ED25519_CERT: 888 key = sensitive_data.host_certificates[i]; 889 break; 890 default: 891 key = sensitive_data.host_keys[i]; 892 if (key == NULL && !need_private) 893 key = sensitive_data.host_pubkeys[i]; 894 break; 895 } 896 if (key != NULL && key->type == type && 897 (key->type != KEY_ECDSA || key->ecdsa_nid == nid)) 898 return need_private ? 899 sensitive_data.host_keys[i] : key; 900 } 901 return NULL; 902} 903 904Key * 905get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 906{ 907 return get_hostkey_by_type(type, nid, 0, ssh); 908} 909 910Key * 911get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 912{ 913 return get_hostkey_by_type(type, nid, 1, ssh); 914} 915 916Key * 917get_hostkey_by_index(int ind) 918{ 919 if (ind < 0 || ind >= options.num_host_key_files) 920 return (NULL); 921 return (sensitive_data.host_keys[ind]); 922} 923 924Key * 925get_hostkey_public_by_index(int ind, struct ssh *ssh) 926{ 927 if (ind < 0 || ind >= options.num_host_key_files) 928 return (NULL); 929 return (sensitive_data.host_pubkeys[ind]); 930} 931 932int 933get_hostkey_index(Key *key, int compare, struct ssh *ssh) 934{ 935 int i; 936 937 for (i = 0; i < options.num_host_key_files; i++) { 938 if (key_is_cert(key)) { 939 if (key == sensitive_data.host_certificates[i] || 940 (compare && sensitive_data.host_certificates[i] && 941 sshkey_equal(key, 942 sensitive_data.host_certificates[i]))) 943 return (i); 944 } else { 945 if (key == sensitive_data.host_keys[i] || 946 (compare && sensitive_data.host_keys[i] && 947 sshkey_equal(key, sensitive_data.host_keys[i]))) 948 return (i); 949 if (key == sensitive_data.host_pubkeys[i] || 950 (compare && sensitive_data.host_pubkeys[i] && 951 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 952 return (i); 953 } 954 } 955 return (-1); 956} 957 958/* Inform the client of all hostkeys */ 959static void 960notify_hostkeys(struct ssh *ssh) 961{ 962 struct sshbuf *buf; 963 struct sshkey *key; 964 int i, nkeys, r; 965 char *fp; 966 967 /* Some clients cannot cope with the hostkeys message, skip those. */ 968 if (datafellows & SSH_BUG_HOSTKEYS) 969 return; 970 971 if ((buf = sshbuf_new()) == NULL) 972 fatal("%s: sshbuf_new", __func__); 973 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 974 key = get_hostkey_public_by_index(i, ssh); 975 if (key == NULL || key->type == KEY_UNSPEC || 976 key->type == KEY_RSA1 || sshkey_is_cert(key)) 977 continue; 978 fp = sshkey_fingerprint(key, options.fingerprint_hash, 979 SSH_FP_DEFAULT); 980 debug3("%s: key %d: %s %s", __func__, i, 981 sshkey_ssh_name(key), fp); 982 free(fp); 983 if (nkeys == 0) { 984 packet_start(SSH2_MSG_GLOBAL_REQUEST); 985 packet_put_cstring("hostkeys-00@openssh.com"); 986 packet_put_char(0); /* want-reply */ 987 } 988 sshbuf_reset(buf); 989 if ((r = sshkey_putb(key, buf)) != 0) 990 fatal("%s: couldn't put hostkey %d: %s", 991 __func__, i, ssh_err(r)); 992 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf)); 993 nkeys++; 994 } 995 debug3("%s: sent %d hostkeys", __func__, nkeys); 996 if (nkeys == 0) 997 fatal("%s: no hostkeys", __func__); 998 packet_send(); 999 sshbuf_free(buf); 1000} 1001 1002/* 1003 * returns 1 if connection should be dropped, 0 otherwise. 1004 * dropping starts at connection #max_startups_begin with a probability 1005 * of (max_startups_rate/100). the probability increases linearly until 1006 * all connections are dropped for startups > max_startups 1007 */ 1008static int 1009drop_connection(int startups) 1010{ 1011 int p, r; 1012 1013 if (startups < options.max_startups_begin) 1014 return 0; 1015 if (startups >= options.max_startups) 1016 return 1; 1017 if (options.max_startups_rate == 100) 1018 return 1; 1019 1020 p = 100 - options.max_startups_rate; 1021 p *= startups - options.max_startups_begin; 1022 p /= options.max_startups - options.max_startups_begin; 1023 p += options.max_startups_rate; 1024 r = arc4random_uniform(100); 1025 1026 debug("drop_connection: p %d, r %d", p, r); 1027 return (r < p) ? 1 : 0; 1028} 1029 1030static void 1031usage(void) 1032{ 1033 if (options.version_addendum && *options.version_addendum != '\0') 1034 fprintf(stderr, "%s %s, %s\n", 1035 SSH_RELEASE, 1036 options.version_addendum, OPENSSL_VERSION); 1037 else 1038 fprintf(stderr, "%s, %s\n", 1039 SSH_RELEASE, OPENSSL_VERSION); 1040 fprintf(stderr, 1041"usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 1042" [-E log_file] [-f config_file] [-g login_grace_time]\n" 1043" [-h host_key_file] [-k key_gen_time] [-o option] [-p port]\n" 1044" [-u len]\n" 1045 ); 1046 exit(1); 1047} 1048 1049static void 1050send_rexec_state(int fd, struct sshbuf *conf) 1051{ 1052 struct sshbuf *m; 1053 int r; 1054 1055 debug3("%s: entering fd = %d config len %zu", __func__, fd, 1056 sshbuf_len(conf)); 1057 1058 /* 1059 * Protocol from reexec master to child: 1060 * string configuration 1061 * u_int ephemeral_key_follows 1062 * bignum e (only if ephemeral_key_follows == 1) 1063 * bignum n " 1064 * bignum d " 1065 * bignum iqmp " 1066 * bignum p " 1067 * bignum q " 1068 * string rngseed (only if OpenSSL is not self-seeded) 1069 */ 1070 if ((m = sshbuf_new()) == NULL) 1071 fatal("%s: sshbuf_new failed", __func__); 1072 if ((r = sshbuf_put_stringb(m, conf)) != 0) 1073 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1074 1075#ifdef WITH_SSH1 1076 if (sensitive_data.server_key != NULL && 1077 sensitive_data.server_key->type == KEY_RSA1) { 1078 if ((r = sshbuf_put_u32(m, 1)) != 0 || 1079 (r = sshbuf_put_bignum1(m, 1080 sensitive_data.server_key->rsa->e)) != 0 || 1081 (r = sshbuf_put_bignum1(m, 1082 sensitive_data.server_key->rsa->n)) != 0 || 1083 (r = sshbuf_put_bignum1(m, 1084 sensitive_data.server_key->rsa->d)) != 0 || 1085 (r = sshbuf_put_bignum1(m, 1086 sensitive_data.server_key->rsa->iqmp)) != 0 || 1087 (r = sshbuf_put_bignum1(m, 1088 sensitive_data.server_key->rsa->p)) != 0 || 1089 (r = sshbuf_put_bignum1(m, 1090 sensitive_data.server_key->rsa->q)) != 0) 1091 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1092 } else 1093#endif 1094 if ((r = sshbuf_put_u32(m, 0)) != 0) 1095 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1096 1097#if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 1098 rexec_send_rng_seed(m); 1099#endif 1100 1101 if (ssh_msg_send(fd, 0, m) == -1) 1102 fatal("%s: ssh_msg_send failed", __func__); 1103 1104 sshbuf_free(m); 1105 1106 debug3("%s: done", __func__); 1107} 1108 1109static void 1110recv_rexec_state(int fd, Buffer *conf) 1111{ 1112 Buffer m; 1113 char *cp; 1114 u_int len; 1115 1116 debug3("%s: entering fd = %d", __func__, fd); 1117 1118 buffer_init(&m); 1119 1120 if (ssh_msg_recv(fd, &m) == -1) 1121 fatal("%s: ssh_msg_recv failed", __func__); 1122 if (buffer_get_char(&m) != 0) 1123 fatal("%s: rexec version mismatch", __func__); 1124 1125 cp = buffer_get_string(&m, &len); 1126 if (conf != NULL) 1127 buffer_append(conf, cp, len); 1128 free(cp); 1129 1130 if (buffer_get_int(&m)) { 1131#ifdef WITH_SSH1 1132 if (sensitive_data.server_key != NULL) 1133 key_free(sensitive_data.server_key); 1134 sensitive_data.server_key = key_new_private(KEY_RSA1); 1135 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 1136 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 1137 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 1138 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 1139 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 1140 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 1141 if (rsa_generate_additional_parameters( 1142 sensitive_data.server_key->rsa) != 0) 1143 fatal("%s: rsa_generate_additional_parameters " 1144 "error", __func__); 1145#endif 1146 } 1147 1148#if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 1149 rexec_recv_rng_seed(&m); 1150#endif 1151 1152 buffer_free(&m); 1153 1154 debug3("%s: done", __func__); 1155} 1156 1157/* Accept a connection from inetd */ 1158static void 1159server_accept_inetd(int *sock_in, int *sock_out) 1160{ 1161 int fd; 1162 1163 startup_pipe = -1; 1164 if (rexeced_flag) { 1165 close(REEXEC_CONFIG_PASS_FD); 1166 *sock_in = *sock_out = dup(STDIN_FILENO); 1167 if (!debug_flag) { 1168 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1169 close(REEXEC_STARTUP_PIPE_FD); 1170 } 1171 } else { 1172 *sock_in = dup(STDIN_FILENO); 1173 *sock_out = dup(STDOUT_FILENO); 1174 } 1175 /* 1176 * We intentionally do not close the descriptors 0, 1, and 2 1177 * as our code for setting the descriptors won't work if 1178 * ttyfd happens to be one of those. 1179 */ 1180 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1181 dup2(fd, STDIN_FILENO); 1182 dup2(fd, STDOUT_FILENO); 1183 if (!log_stderr) 1184 dup2(fd, STDERR_FILENO); 1185 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1186 close(fd); 1187 } 1188 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1189} 1190 1191/* 1192 * Listen for TCP connections 1193 */ 1194static void 1195server_listen(void) 1196{ 1197 int ret, listen_sock, on = 1; 1198 struct addrinfo *ai; 1199 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1200 int socksize; 1201 socklen_t len; 1202 1203 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1204 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1205 continue; 1206 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1207 fatal("Too many listen sockets. " 1208 "Enlarge MAX_LISTEN_SOCKS"); 1209 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1210 ntop, sizeof(ntop), strport, sizeof(strport), 1211 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1212 error("getnameinfo failed: %.100s", 1213 ssh_gai_strerror(ret)); 1214 continue; 1215 } 1216 /* Create socket for listening. */ 1217 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1218 ai->ai_protocol); 1219 if (listen_sock < 0) { 1220 /* kernel may not support ipv6 */ 1221 verbose("socket: %.100s", strerror(errno)); 1222 continue; 1223 } 1224 if (set_nonblock(listen_sock) == -1) { 1225 close(listen_sock); 1226 continue; 1227 } 1228 /* 1229 * Set socket options. 1230 * Allow local port reuse in TIME_WAIT. 1231 */ 1232 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1233 &on, sizeof(on)) == -1) 1234 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1235 1236 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1237 if (ai->ai_family == AF_INET6) 1238 sock_set_v6only(listen_sock); 1239 1240 debug("Bind to port %s on %s.", strport, ntop); 1241 1242 len = sizeof(socksize); 1243 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len); 1244 debug("Server TCP RWIN socket size: %d", socksize); 1245 1246 /* Bind the socket to the desired port. */ 1247 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1248 error("Bind to port %s on %s failed: %.200s.", 1249 strport, ntop, strerror(errno)); 1250 close(listen_sock); 1251 continue; 1252 } 1253 listen_socks[num_listen_socks] = listen_sock; 1254 num_listen_socks++; 1255 1256 /* Start listening on the port. */ 1257 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1258 fatal("listen on [%s]:%s: %.100s", 1259 ntop, strport, strerror(errno)); 1260 logit("Server listening on %s port %s.", ntop, strport); 1261 } 1262 freeaddrinfo(options.listen_addrs); 1263 1264 if (!num_listen_socks) 1265 fatal("Cannot bind any address."); 1266} 1267 1268/* 1269 * The main TCP accept loop. Note that, for the non-debug case, returns 1270 * from this function are in a forked subprocess. 1271 */ 1272static void 1273server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1274{ 1275 fd_set *fdset; 1276 int i, j, ret, maxfd; 1277 int key_used = 0, startups = 0; 1278 int startup_p[2] = { -1 , -1 }; 1279 struct sockaddr_storage from; 1280 socklen_t fromlen; 1281 pid_t pid; 1282 u_char rnd[256]; 1283 1284 /* setup fd set for accept */ 1285 fdset = NULL; 1286 maxfd = 0; 1287 for (i = 0; i < num_listen_socks; i++) 1288 if (listen_socks[i] > maxfd) 1289 maxfd = listen_socks[i]; 1290 /* pipes connected to unauthenticated childs */ 1291 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1292 for (i = 0; i < options.max_startups; i++) 1293 startup_pipes[i] = -1; 1294 1295 /* 1296 * Stay listening for connections until the system crashes or 1297 * the daemon is killed with a signal. 1298 */ 1299 for (;;) { 1300 if (received_sighup) 1301 sighup_restart(); 1302 free(fdset); 1303 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1304 sizeof(fd_mask)); 1305 1306 for (i = 0; i < num_listen_socks; i++) 1307 FD_SET(listen_socks[i], fdset); 1308 for (i = 0; i < options.max_startups; i++) 1309 if (startup_pipes[i] != -1) 1310 FD_SET(startup_pipes[i], fdset); 1311 1312 /* Wait in select until there is a connection. */ 1313 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1314 if (ret < 0 && errno != EINTR) 1315 error("select: %.100s", strerror(errno)); 1316 if (received_sigterm) { 1317 logit("Received signal %d; terminating.", 1318 (int) received_sigterm); 1319 close_listen_socks(); 1320 if (options.pid_file != NULL) 1321 unlink(options.pid_file); 1322 exit(received_sigterm == SIGTERM ? 0 : 255); 1323 } 1324 if (key_used && key_do_regen) { 1325 generate_ephemeral_server_key(); 1326 key_used = 0; 1327 key_do_regen = 0; 1328 } 1329 if (ret < 0) 1330 continue; 1331 1332 for (i = 0; i < options.max_startups; i++) 1333 if (startup_pipes[i] != -1 && 1334 FD_ISSET(startup_pipes[i], fdset)) { 1335 /* 1336 * the read end of the pipe is ready 1337 * if the child has closed the pipe 1338 * after successful authentication 1339 * or if the child has died 1340 */ 1341 close(startup_pipes[i]); 1342 startup_pipes[i] = -1; 1343 startups--; 1344 } 1345 for (i = 0; i < num_listen_socks; i++) { 1346 if (!FD_ISSET(listen_socks[i], fdset)) 1347 continue; 1348 fromlen = sizeof(from); 1349 *newsock = accept(listen_socks[i], 1350 (struct sockaddr *)&from, &fromlen); 1351 if (*newsock < 0) { 1352 if (errno != EINTR && errno != EWOULDBLOCK && 1353 errno != ECONNABORTED && errno != EAGAIN) 1354 error("accept: %.100s", 1355 strerror(errno)); 1356 if (errno == EMFILE || errno == ENFILE) 1357 usleep(100 * 1000); 1358 continue; 1359 } 1360 if (unset_nonblock(*newsock) == -1) { 1361 close(*newsock); 1362 continue; 1363 } 1364 if (drop_connection(startups) == 1) { 1365 debug("drop connection #%d", startups); 1366 close(*newsock); 1367 continue; 1368 } 1369 if (pipe(startup_p) == -1) { 1370 close(*newsock); 1371 continue; 1372 } 1373 1374 if (rexec_flag && socketpair(AF_UNIX, 1375 SOCK_STREAM, 0, config_s) == -1) { 1376 error("reexec socketpair: %s", 1377 strerror(errno)); 1378 close(*newsock); 1379 close(startup_p[0]); 1380 close(startup_p[1]); 1381 continue; 1382 } 1383 1384 for (j = 0; j < options.max_startups; j++) 1385 if (startup_pipes[j] == -1) { 1386 startup_pipes[j] = startup_p[0]; 1387 if (maxfd < startup_p[0]) 1388 maxfd = startup_p[0]; 1389 startups++; 1390 break; 1391 } 1392 1393 /* 1394 * Got connection. Fork a child to handle it, unless 1395 * we are in debugging mode. 1396 */ 1397 if (debug_flag) { 1398 /* 1399 * In debugging mode. Close the listening 1400 * socket, and start processing the 1401 * connection without forking. 1402 */ 1403 debug("Server will not fork when running in debugging mode."); 1404 close_listen_socks(); 1405 *sock_in = *newsock; 1406 *sock_out = *newsock; 1407 close(startup_p[0]); 1408 close(startup_p[1]); 1409 startup_pipe = -1; 1410 pid = getpid(); 1411 if (rexec_flag) { 1412 send_rexec_state(config_s[0], 1413 &cfg); 1414 close(config_s[0]); 1415 } 1416 break; 1417 } 1418 1419 /* 1420 * Normal production daemon. Fork, and have 1421 * the child process the connection. The 1422 * parent continues listening. 1423 */ 1424 platform_pre_fork(); 1425 if ((pid = fork()) == 0) { 1426 /* 1427 * Child. Close the listening and 1428 * max_startup sockets. Start using 1429 * the accepted socket. Reinitialize 1430 * logging (since our pid has changed). 1431 * We break out of the loop to handle 1432 * the connection. 1433 */ 1434 platform_post_fork_child(); 1435 startup_pipe = startup_p[1]; 1436 close_startup_pipes(); 1437 close_listen_socks(); 1438 *sock_in = *newsock; 1439 *sock_out = *newsock; 1440 log_init(__progname, 1441 options.log_level, 1442 options.log_facility, 1443 log_stderr); 1444 if (rexec_flag) 1445 close(config_s[0]); 1446 break; 1447 } 1448 1449 /* Parent. Stay in the loop. */ 1450 platform_post_fork_parent(pid); 1451 if (pid < 0) 1452 error("fork: %.100s", strerror(errno)); 1453 else 1454 debug("Forked child %ld.", (long)pid); 1455 1456 close(startup_p[1]); 1457 1458 if (rexec_flag) { 1459 send_rexec_state(config_s[0], &cfg); 1460 close(config_s[0]); 1461 close(config_s[1]); 1462 } 1463 1464 /* 1465 * Mark that the key has been used (it 1466 * was "given" to the child). 1467 */ 1468 if ((options.protocol & SSH_PROTO_1) && 1469 key_used == 0) { 1470 /* Schedule server key regeneration alarm. */ 1471 signal(SIGALRM, key_regeneration_alarm); 1472 alarm(options.key_regeneration_time); 1473 key_used = 1; 1474 } 1475 1476 close(*newsock); 1477 1478 /* 1479 * Ensure that our random state differs 1480 * from that of the child 1481 */ 1482 arc4random_stir(); 1483 arc4random_buf(rnd, sizeof(rnd)); 1484#ifdef WITH_OPENSSL 1485 RAND_seed(rnd, sizeof(rnd)); 1486 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 1487 fatal("%s: RAND_bytes failed", __func__); 1488#endif 1489 explicit_bzero(rnd, sizeof(rnd)); 1490 } 1491 1492 /* child process check (or debug mode) */ 1493 if (num_listen_socks < 0) 1494 break; 1495 } 1496} 1497 1498/* 1499 * If IP options are supported, make sure there are none (log and 1500 * return an error if any are found). Basically we are worried about 1501 * source routing; it can be used to pretend you are somebody 1502 * (ip-address) you are not. That itself may be "almost acceptable" 1503 * under certain circumstances, but rhosts autentication is useless 1504 * if source routing is accepted. Notice also that if we just dropped 1505 * source routing here, the other side could use IP spoofing to do 1506 * rest of the interaction and could still bypass security. So we 1507 * exit here if we detect any IP options. 1508 */ 1509static void 1510check_ip_options(struct ssh *ssh) 1511{ 1512#ifdef IP_OPTIONS 1513 int sock_in = ssh_packet_get_connection_in(ssh); 1514 struct sockaddr_storage from; 1515 socklen_t option_size, i, fromlen = sizeof(from); 1516 u_char opts[200]; 1517 char text[sizeof(opts) * 3 + 1]; 1518 1519 memset(&from, 0, sizeof(from)); 1520 if (getpeername(sock_in, (struct sockaddr *)&from, 1521 &fromlen) < 0) 1522 return; 1523 if (from.ss_family != AF_INET) 1524 return; 1525 /* XXX IPv6 options? */ 1526 1527 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1528 &option_size) >= 0 && option_size != 0) { 1529 text[0] = '\0'; 1530 for (i = 0; i < option_size; i++) 1531 snprintf(text + i*3, sizeof(text) - i*3, 1532 " %2.2x", opts[i]); 1533 fatal("Connection from %.100s port %d with IP opts: %.800s", 1534 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1535 } 1536 return; 1537#endif /* IP_OPTIONS */ 1538} 1539 1540/* 1541 * Main program for the daemon. 1542 */ 1543int 1544main(int ac, char **av) 1545{ 1546 struct ssh *ssh = NULL; 1547 extern char *optarg; 1548 extern int optind; 1549 int r, opt, i, j, on = 1; 1550 int sock_in = -1, sock_out = -1, newsock = -1; 1551 const char *remote_ip; 1552 int remote_port; 1553 char *fp, *line, *laddr, *logfile = NULL; 1554 int config_s[2] = { -1 , -1 }; 1555 u_int n; 1556 u_int64_t ibytes, obytes; 1557 mode_t new_umask; 1558 Key *key; 1559 Key *pubkey; 1560 int keytype; 1561 Authctxt *authctxt; 1562 struct connection_info *connection_info = get_connection_info(0, 0); 1563 1564 ssh_malloc_init(); /* must be called before any mallocs */ 1565 1566#ifdef HAVE_SECUREWARE 1567 (void)set_auth_parameters(ac, av); 1568#endif 1569 __progname = ssh_get_progname(av[0]); 1570 1571 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1572 saved_argc = ac; 1573 rexec_argc = ac; 1574 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1575 for (i = 0; i < ac; i++) 1576 saved_argv[i] = xstrdup(av[i]); 1577 saved_argv[i] = NULL; 1578 1579#ifndef HAVE_SETPROCTITLE 1580 /* Prepare for later setproctitle emulation */ 1581 compat_init_setproctitle(ac, av); 1582 av = saved_argv; 1583#endif 1584 1585 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1586 debug("setgroups(): %.200s", strerror(errno)); 1587 1588 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1589 sanitise_stdfd(); 1590 1591 /* Initialize configuration options to their default values. */ 1592 initialize_server_options(&options); 1593 1594 /* Parse command-line arguments. */ 1595 while ((opt = getopt(ac, av, 1596 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1597 switch (opt) { 1598 case '4': 1599 options.address_family = AF_INET; 1600 break; 1601 case '6': 1602 options.address_family = AF_INET6; 1603 break; 1604 case 'f': 1605 config_file_name = optarg; 1606 break; 1607 case 'c': 1608 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1609 fprintf(stderr, "too many host certificates.\n"); 1610 exit(1); 1611 } 1612 options.host_cert_files[options.num_host_cert_files++] = 1613 derelativise_path(optarg); 1614 break; 1615 case 'd': 1616 if (debug_flag == 0) { 1617 debug_flag = 1; 1618 options.log_level = SYSLOG_LEVEL_DEBUG1; 1619 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1620 options.log_level++; 1621 break; 1622 case 'D': 1623 no_daemon_flag = 1; 1624 break; 1625 case 'E': 1626 logfile = optarg; 1627 /* FALLTHROUGH */ 1628 case 'e': 1629 log_stderr = 1; 1630 break; 1631 case 'i': 1632 inetd_flag = 1; 1633 break; 1634 case 'r': 1635 rexec_flag = 0; 1636 break; 1637 case 'R': 1638 rexeced_flag = 1; 1639 inetd_flag = 1; 1640 break; 1641 case 'Q': 1642 /* ignored */ 1643 break; 1644 case 'q': 1645 options.log_level = SYSLOG_LEVEL_QUIET; 1646 break; 1647 case 'b': 1648 options.server_key_bits = (int)strtonum(optarg, 256, 1649 32768, NULL); 1650 break; 1651 case 'p': 1652 options.ports_from_cmdline = 1; 1653 if (options.num_ports >= MAX_PORTS) { 1654 fprintf(stderr, "too many ports.\n"); 1655 exit(1); 1656 } 1657 options.ports[options.num_ports++] = a2port(optarg); 1658 if (options.ports[options.num_ports-1] <= 0) { 1659 fprintf(stderr, "Bad port number.\n"); 1660 exit(1); 1661 } 1662 break; 1663 case 'g': 1664 if ((options.login_grace_time = convtime(optarg)) == -1) { 1665 fprintf(stderr, "Invalid login grace time.\n"); 1666 exit(1); 1667 } 1668 break; 1669 case 'k': 1670 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1671 fprintf(stderr, "Invalid key regeneration interval.\n"); 1672 exit(1); 1673 } 1674 break; 1675 case 'h': 1676 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1677 fprintf(stderr, "too many host keys.\n"); 1678 exit(1); 1679 } 1680 options.host_key_files[options.num_host_key_files++] = 1681 derelativise_path(optarg); 1682 break; 1683 case 't': 1684 test_flag = 1; 1685 break; 1686 case 'T': 1687 test_flag = 2; 1688 break; 1689 case 'C': 1690 if (parse_server_match_testspec(connection_info, 1691 optarg) == -1) 1692 exit(1); 1693 break; 1694 case 'u': 1695 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1696 if (utmp_len > HOST_NAME_MAX+1) { 1697 fprintf(stderr, "Invalid utmp length.\n"); 1698 exit(1); 1699 } 1700 break; 1701 case 'o': 1702 line = xstrdup(optarg); 1703 if (process_server_config_line(&options, line, 1704 "command-line", 0, NULL, NULL) != 0) 1705 exit(1); 1706 free(line); 1707 break; 1708 case '?': 1709 default: 1710 usage(); 1711 break; 1712 } 1713 } 1714 if (rexeced_flag || inetd_flag) 1715 rexec_flag = 0; 1716 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1717 fatal("sshd re-exec requires execution with an absolute path"); 1718 if (rexeced_flag) 1719 closefrom(REEXEC_MIN_FREE_FD); 1720 else 1721 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1722 1723#ifdef WITH_OPENSSL 1724 OpenSSL_add_all_algorithms(); 1725#endif 1726 1727 /* If requested, redirect the logs to the specified logfile. */ 1728 if (logfile != NULL) 1729 log_redirect_stderr_to(logfile); 1730 /* 1731 * Force logging to stderr until we have loaded the private host 1732 * key (unless started from inetd) 1733 */ 1734 log_init(__progname, 1735 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1736 SYSLOG_LEVEL_INFO : options.log_level, 1737 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1738 SYSLOG_FACILITY_AUTH : options.log_facility, 1739 log_stderr || !inetd_flag); 1740 1741 /* 1742 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1743 * root's environment 1744 */ 1745 if (getenv("KRB5CCNAME") != NULL) 1746 (void) unsetenv("KRB5CCNAME"); 1747 1748#ifdef _UNICOS 1749 /* Cray can define user privs drop all privs now! 1750 * Not needed on PRIV_SU systems! 1751 */ 1752 drop_cray_privs(); 1753#endif 1754 1755 sensitive_data.server_key = NULL; 1756 sensitive_data.ssh1_host_key = NULL; 1757 sensitive_data.have_ssh1_key = 0; 1758 sensitive_data.have_ssh2_key = 0; 1759 1760 /* 1761 * If we're doing an extended config test, make sure we have all of 1762 * the parameters we need. If we're not doing an extended test, 1763 * do not silently ignore connection test params. 1764 */ 1765 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0) 1766 fatal("user, host and addr are all required when testing " 1767 "Match configs"); 1768 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0) 1769 fatal("Config test connection parameter (-C) provided without " 1770 "test mode (-T)"); 1771 1772 /* Fetch our configuration */ 1773 buffer_init(&cfg); 1774 if (rexeced_flag) 1775 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1776 else if (strcasecmp(config_file_name, "none") != 0) 1777 load_server_config(config_file_name, &cfg); 1778 1779 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1780 &cfg, NULL); 1781 1782 seed_rng(); 1783 1784 /* Fill in default values for those options not explicitly set. */ 1785 fill_default_server_options(&options); 1786 1787 /* challenge-response is implemented via keyboard interactive */ 1788 if (options.challenge_response_authentication) 1789 options.kbd_interactive_authentication = 1; 1790 1791 /* Check that options are sensible */ 1792 if (options.authorized_keys_command_user == NULL && 1793 (options.authorized_keys_command != NULL && 1794 strcasecmp(options.authorized_keys_command, "none") != 0)) 1795 fatal("AuthorizedKeysCommand set without " 1796 "AuthorizedKeysCommandUser"); 1797 if (options.authorized_principals_command_user == NULL && 1798 (options.authorized_principals_command != NULL && 1799 strcasecmp(options.authorized_principals_command, "none") != 0)) 1800 fatal("AuthorizedPrincipalsCommand set without " 1801 "AuthorizedPrincipalsCommandUser"); 1802 1803 /* 1804 * Check whether there is any path through configured auth methods. 1805 * Unfortunately it is not possible to verify this generally before 1806 * daemonisation in the presence of Match block, but this catches 1807 * and warns for trivial misconfigurations that could break login. 1808 */ 1809 if (options.num_auth_methods != 0) { 1810 if ((options.protocol & SSH_PROTO_1)) 1811 fatal("AuthenticationMethods is not supported with " 1812 "SSH protocol 1"); 1813 for (n = 0; n < options.num_auth_methods; n++) { 1814 if (auth2_methods_valid(options.auth_methods[n], 1815 1) == 0) 1816 break; 1817 } 1818 if (n >= options.num_auth_methods) 1819 fatal("AuthenticationMethods cannot be satisfied by " 1820 "enabled authentication methods"); 1821 } 1822 1823 /* set default channel AF */ 1824 channel_set_af(options.address_family); 1825 1826 /* Check that there are no remaining arguments. */ 1827 if (optind < ac) { 1828 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1829 exit(1); 1830 } 1831 1832 debug("sshd version %s, %s", SSH_VERSION, 1833#ifdef WITH_OPENSSL 1834 SSLeay_version(SSLEAY_VERSION) 1835#else 1836 "without OpenSSL" 1837#endif 1838 ); 1839 1840 /* Store privilege separation user for later use if required. */ 1841 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1842 if (use_privsep || options.kerberos_authentication) 1843 fatal("Privilege separation user %s does not exist", 1844 SSH_PRIVSEP_USER); 1845 } else { 1846 explicit_bzero(privsep_pw->pw_passwd, 1847 strlen(privsep_pw->pw_passwd)); 1848 privsep_pw = pwcopy(privsep_pw); 1849 free(privsep_pw->pw_passwd); 1850 privsep_pw->pw_passwd = xstrdup("*"); 1851 } 1852 endpwent(); 1853 1854 /* load host keys */ 1855 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1856 sizeof(Key *)); 1857 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1858 sizeof(Key *)); 1859 1860 if (options.host_key_agent) { 1861 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1862 setenv(SSH_AUTHSOCKET_ENV_NAME, 1863 options.host_key_agent, 1); 1864 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1865 have_agent = 1; 1866 else 1867 error("Could not connect to agent \"%s\": %s", 1868 options.host_key_agent, ssh_err(r)); 1869 } 1870 1871 for (i = 0; i < options.num_host_key_files; i++) { 1872 if (options.host_key_files[i] == NULL) 1873 continue; 1874 key = key_load_private(options.host_key_files[i], "", NULL); 1875 pubkey = key_load_public(options.host_key_files[i], NULL); 1876 if (pubkey == NULL && key != NULL) 1877 pubkey = key_demote(key); 1878 sensitive_data.host_keys[i] = key; 1879 sensitive_data.host_pubkeys[i] = pubkey; 1880 1881 if (key == NULL && pubkey != NULL && pubkey->type != KEY_RSA1 && 1882 have_agent) { 1883 debug("will rely on agent for hostkey %s", 1884 options.host_key_files[i]); 1885 keytype = pubkey->type; 1886 } else if (key != NULL) { 1887 keytype = key->type; 1888 } else { 1889 error("Could not load host key: %s", 1890 options.host_key_files[i]); 1891 sensitive_data.host_keys[i] = NULL; 1892 sensitive_data.host_pubkeys[i] = NULL; 1893 continue; 1894 } 1895 1896 switch (keytype) { 1897 case KEY_RSA1: 1898 sensitive_data.ssh1_host_key = key; 1899 sensitive_data.have_ssh1_key = 1; 1900 break; 1901 case KEY_RSA: 1902 case KEY_DSA: 1903 case KEY_ECDSA: 1904 case KEY_ED25519: 1905 if (have_agent || key != NULL) 1906 sensitive_data.have_ssh2_key = 1; 1907 break; 1908 } 1909 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1910 SSH_FP_DEFAULT)) == NULL) 1911 fatal("sshkey_fingerprint failed"); 1912 debug("%s host key #%d: %s %s", 1913 key ? "private" : "agent", i, keytype == KEY_RSA1 ? 1914 sshkey_type(pubkey) : sshkey_ssh_name(pubkey), fp); 1915 free(fp); 1916 } 1917 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1918 logit("Disabling protocol version 1. Could not load host key"); 1919 options.protocol &= ~SSH_PROTO_1; 1920 } 1921 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1922 logit("Disabling protocol version 2. Could not load host key"); 1923 options.protocol &= ~SSH_PROTO_2; 1924 } 1925 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1926 logit("sshd: no hostkeys available -- exiting."); 1927 exit(1); 1928 } 1929 1930 /* 1931 * Load certificates. They are stored in an array at identical 1932 * indices to the public keys that they relate to. 1933 */ 1934 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1935 sizeof(Key *)); 1936 for (i = 0; i < options.num_host_key_files; i++) 1937 sensitive_data.host_certificates[i] = NULL; 1938 1939 for (i = 0; i < options.num_host_cert_files; i++) { 1940 if (options.host_cert_files[i] == NULL) 1941 continue; 1942 key = key_load_public(options.host_cert_files[i], NULL); 1943 if (key == NULL) { 1944 error("Could not load host certificate: %s", 1945 options.host_cert_files[i]); 1946 continue; 1947 } 1948 if (!key_is_cert(key)) { 1949 error("Certificate file is not a certificate: %s", 1950 options.host_cert_files[i]); 1951 key_free(key); 1952 continue; 1953 } 1954 /* Find matching private key */ 1955 for (j = 0; j < options.num_host_key_files; j++) { 1956 if (key_equal_public(key, 1957 sensitive_data.host_keys[j])) { 1958 sensitive_data.host_certificates[j] = key; 1959 break; 1960 } 1961 } 1962 if (j >= options.num_host_key_files) { 1963 error("No matching private key for certificate: %s", 1964 options.host_cert_files[i]); 1965 key_free(key); 1966 continue; 1967 } 1968 sensitive_data.host_certificates[j] = key; 1969 debug("host certificate: #%d type %d %s", j, key->type, 1970 key_type(key)); 1971 } 1972 1973#ifdef WITH_SSH1 1974 /* Check certain values for sanity. */ 1975 if (options.protocol & SSH_PROTO_1) { 1976 if (options.server_key_bits < SSH_RSA_MINIMUM_MODULUS_SIZE || 1977 options.server_key_bits > OPENSSL_RSA_MAX_MODULUS_BITS) { 1978 fprintf(stderr, "Bad server key size.\n"); 1979 exit(1); 1980 } 1981 /* 1982 * Check that server and host key lengths differ sufficiently. This 1983 * is necessary to make double encryption work with rsaref. Oh, I 1984 * hate software patents. I dont know if this can go? Niels 1985 */ 1986 if (options.server_key_bits > 1987 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1988 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1989 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1990 SSH_KEY_BITS_RESERVED) { 1991 options.server_key_bits = 1992 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1993 SSH_KEY_BITS_RESERVED; 1994 debug("Forcing server key to %d bits to make it differ from host key.", 1995 options.server_key_bits); 1996 } 1997 } 1998#endif 1999 2000 if (use_privsep) { 2001 struct stat st; 2002 2003 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 2004 (S_ISDIR(st.st_mode) == 0)) 2005 fatal("Missing privilege separation directory: %s", 2006 _PATH_PRIVSEP_CHROOT_DIR); 2007 2008#ifdef HAVE_CYGWIN 2009 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 2010 (st.st_uid != getuid () || 2011 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 2012#else 2013 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 2014#endif 2015 fatal("%s must be owned by root and not group or " 2016 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 2017 } 2018 2019 if (test_flag > 1) { 2020 if (server_match_spec_complete(connection_info) == 1) 2021 parse_server_match_config(&options, connection_info); 2022 dump_config(&options); 2023 } 2024 2025 /* Configuration looks good, so exit if in test mode. */ 2026 if (test_flag) 2027 exit(0); 2028 2029 /* 2030 * Clear out any supplemental groups we may have inherited. This 2031 * prevents inadvertent creation of files with bad modes (in the 2032 * portable version at least, it's certainly possible for PAM 2033 * to create a file, and we can't control the code in every 2034 * module which might be used). 2035 */ 2036 if (setgroups(0, NULL) < 0) 2037 debug("setgroups() failed: %.200s", strerror(errno)); 2038 2039 if (rexec_flag) { 2040 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 2041 for (i = 0; i < rexec_argc; i++) { 2042 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 2043 rexec_argv[i] = saved_argv[i]; 2044 } 2045 rexec_argv[rexec_argc] = "-R"; 2046 rexec_argv[rexec_argc + 1] = NULL; 2047 } 2048 2049 /* Ensure that umask disallows at least group and world write */ 2050 new_umask = umask(0077) | 0022; 2051 (void) umask(new_umask); 2052 2053 /* Initialize the log (it is reinitialized below in case we forked). */ 2054 if (debug_flag && (!inetd_flag || rexeced_flag)) 2055 log_stderr = 1; 2056 log_init(__progname, options.log_level, options.log_facility, log_stderr); 2057 2058 /* 2059 * If not in debugging mode, and not started from inetd, disconnect 2060 * from the controlling terminal, and fork. The original process 2061 * exits. 2062 */ 2063 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 2064#ifdef TIOCNOTTY 2065 int fd; 2066#endif /* TIOCNOTTY */ 2067 if (daemon(0, 0) < 0) 2068 fatal("daemon() failed: %.200s", strerror(errno)); 2069 2070 /* Disconnect from the controlling tty. */ 2071#ifdef TIOCNOTTY 2072 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 2073 if (fd >= 0) { 2074 (void) ioctl(fd, TIOCNOTTY, NULL); 2075 close(fd); 2076 } 2077#endif /* TIOCNOTTY */ 2078 } 2079 /* Reinitialize the log (because of the fork above). */ 2080 log_init(__progname, options.log_level, options.log_facility, log_stderr); 2081 2082 /* Avoid killing the process in high-pressure swapping environments. */ 2083 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 2084 debug("madvise(): %.200s", strerror(errno)); 2085 2086 /* Chdir to the root directory so that the current disk can be 2087 unmounted if desired. */ 2088 if (chdir("/") == -1) 2089 error("chdir(\"/\"): %s", strerror(errno)); 2090 2091 /* ignore SIGPIPE */ 2092 signal(SIGPIPE, SIG_IGN); 2093 2094 /* Get a connection, either from inetd or a listening TCP socket */ 2095 if (inetd_flag) { 2096 server_accept_inetd(&sock_in, &sock_out); 2097 } else { 2098 platform_pre_listen(); 2099 server_listen(); 2100 2101 if (options.protocol & SSH_PROTO_1) 2102 generate_ephemeral_server_key(); 2103 2104 signal(SIGHUP, sighup_handler); 2105 signal(SIGCHLD, main_sigchld_handler); 2106 signal(SIGTERM, sigterm_handler); 2107 signal(SIGQUIT, sigterm_handler); 2108 2109 /* 2110 * Write out the pid file after the sigterm handler 2111 * is setup and the listen sockets are bound 2112 */ 2113 if (options.pid_file != NULL && !debug_flag) { 2114 FILE *f = fopen(options.pid_file, "w"); 2115 2116 if (f == NULL) { 2117 error("Couldn't create pid file \"%s\": %s", 2118 options.pid_file, strerror(errno)); 2119 } else { 2120 fprintf(f, "%ld\n", (long) getpid()); 2121 fclose(f); 2122 } 2123 } 2124 2125 /* Accept a connection and return in a forked child */ 2126 server_accept_loop(&sock_in, &sock_out, 2127 &newsock, config_s); 2128 } 2129 2130 /* This is the child processing a new connection. */ 2131 setproctitle("%s", "[accepted]"); 2132 2133 /* 2134 * Create a new session and process group since the 4.4BSD 2135 * setlogin() affects the entire process group. We don't 2136 * want the child to be able to affect the parent. 2137 */ 2138#if !defined(SSHD_ACQUIRES_CTTY) 2139 /* 2140 * If setsid is called, on some platforms sshd will later acquire a 2141 * controlling terminal which will result in "could not set 2142 * controlling tty" errors. 2143 */ 2144 if (!debug_flag && !inetd_flag && setsid() < 0) 2145 error("setsid: %.100s", strerror(errno)); 2146#endif 2147 2148 if (rexec_flag) { 2149 int fd; 2150 2151 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 2152 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2153 dup2(newsock, STDIN_FILENO); 2154 dup2(STDIN_FILENO, STDOUT_FILENO); 2155 if (startup_pipe == -1) 2156 close(REEXEC_STARTUP_PIPE_FD); 2157 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 2158 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 2159 close(startup_pipe); 2160 startup_pipe = REEXEC_STARTUP_PIPE_FD; 2161 } 2162 2163 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 2164 close(config_s[1]); 2165 2166 execv(rexec_argv[0], rexec_argv); 2167 2168 /* Reexec has failed, fall back and continue */ 2169 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 2170 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 2171 log_init(__progname, options.log_level, 2172 options.log_facility, log_stderr); 2173 2174 /* Clean up fds */ 2175 close(REEXEC_CONFIG_PASS_FD); 2176 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2177 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 2178 dup2(fd, STDIN_FILENO); 2179 dup2(fd, STDOUT_FILENO); 2180 if (fd > STDERR_FILENO) 2181 close(fd); 2182 } 2183 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2184 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2185 } 2186 2187 /* Executed child processes don't need these. */ 2188 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2189 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2190 2191 /* 2192 * Disable the key regeneration alarm. We will not regenerate the 2193 * key since we are no longer in a position to give it to anyone. We 2194 * will not restart on SIGHUP since it no longer makes sense. 2195 */ 2196 alarm(0); 2197 signal(SIGALRM, SIG_DFL); 2198 signal(SIGHUP, SIG_DFL); 2199 signal(SIGTERM, SIG_DFL); 2200 signal(SIGQUIT, SIG_DFL); 2201 signal(SIGCHLD, SIG_DFL); 2202 signal(SIGINT, SIG_DFL); 2203 2204#ifdef __FreeBSD__ 2205 /* 2206 * Initialize the resolver. This may not happen automatically 2207 * before privsep chroot(). 2208 */ 2209 if ((_res.options & RES_INIT) == 0) { 2210 debug("res_init()"); 2211 res_init(); 2212 } 2213#ifdef GSSAPI 2214 /* 2215 * Force GSS-API to parse its configuration and load any 2216 * mechanism plugins. 2217 */ 2218 { 2219 gss_OID_set mechs; 2220 OM_uint32 minor_status; 2221 gss_indicate_mechs(&minor_status, &mechs); 2222 gss_release_oid_set(&minor_status, &mechs); 2223 } 2224#endif 2225#endif 2226 2227 /* 2228 * Register our connection. This turns encryption off because we do 2229 * not have a key. 2230 */ 2231 packet_set_connection(sock_in, sock_out); 2232 packet_set_server(); 2233 ssh = active_state; /* XXX */ 2234 check_ip_options(ssh); 2235 2236 /* Set SO_KEEPALIVE if requested. */ 2237 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 2238 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 2239 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2240 2241 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2242 debug("ssh_remote_port failed"); 2243 cleanup_exit(255); 2244 } 2245 2246 /* 2247 * The rest of the code depends on the fact that 2248 * ssh_remote_ipaddr() caches the remote ip, even if 2249 * the socket goes away. 2250 */ 2251 remote_ip = ssh_remote_ipaddr(ssh); 2252 2253#ifdef SSH_AUDIT_EVENTS 2254 audit_connection_from(remote_ip, remote_port); 2255#endif 2256#ifdef LIBWRAP 2257 allow_severity = options.log_facility|LOG_INFO; 2258 deny_severity = options.log_facility|LOG_WARNING; 2259 /* Check whether logins are denied from this host. */ 2260 if (packet_connection_is_on_socket()) { 2261 struct request_info req; 2262 2263 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 2264 fromhost(&req); 2265 2266 if (!hosts_access(&req)) { 2267 debug("Connection refused by tcp wrapper"); 2268 refuse(&req); 2269 /* NOTREACHED */ 2270 fatal("libwrap refuse returns"); 2271 } 2272 } 2273#endif /* LIBWRAP */ 2274 2275 /* Log the connection. */ 2276 laddr = get_local_ipaddr(sock_in); 2277 verbose("Connection from %s port %d on %s port %d", 2278 remote_ip, remote_port, laddr, ssh_local_port(ssh)); 2279 free(laddr); 2280 2281 /* 2282 * We don't want to listen forever unless the other side 2283 * successfully authenticates itself. So we set up an alarm which is 2284 * cleared after successful authentication. A limit of zero 2285 * indicates no limit. Note that we don't set the alarm in debugging 2286 * mode; it is just annoying to have the server exit just when you 2287 * are about to discover the bug. 2288 */ 2289 signal(SIGALRM, grace_alarm_handler); 2290 if (!debug_flag) 2291 alarm(options.login_grace_time); 2292 2293 sshd_exchange_identification(ssh, sock_in, sock_out); 2294 2295 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 2296 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 2297 generate_ephemeral_server_key(); 2298 2299 packet_set_nonblocking(); 2300 2301 /* allocate authentication context */ 2302 authctxt = xcalloc(1, sizeof(*authctxt)); 2303 2304 authctxt->loginmsg = &loginmsg; 2305 2306 /* XXX global for cleanup, access from other modules */ 2307 the_authctxt = authctxt; 2308 2309 /* prepare buffer to collect messages to display to user after login */ 2310 buffer_init(&loginmsg); 2311 auth_debug_reset(); 2312 2313 BLACKLIST_INIT(); 2314 2315 if (use_privsep) { 2316 if (privsep_preauth(authctxt) == 1) 2317 goto authenticated; 2318 } else if (compat20 && have_agent) { 2319 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2320 error("Unable to get agent socket: %s", ssh_err(r)); 2321 have_agent = 0; 2322 } 2323 } 2324 2325 /* perform the key exchange */ 2326 /* authenticate user and start session */ 2327 if (compat20) { 2328 do_ssh2_kex(); 2329 do_authentication2(authctxt); 2330 } else { 2331#ifdef WITH_SSH1 2332 do_ssh1_kex(); 2333 do_authentication(authctxt); 2334#else 2335 fatal("ssh1 not supported"); 2336#endif 2337 } 2338 /* 2339 * If we use privilege separation, the unprivileged child transfers 2340 * the current keystate and exits 2341 */ 2342 if (use_privsep) { 2343 mm_send_keystate(pmonitor); 2344 exit(0); 2345 } 2346 2347 authenticated: 2348 /* 2349 * Cancel the alarm we set to limit the time taken for 2350 * authentication. 2351 */ 2352 alarm(0); 2353 signal(SIGALRM, SIG_DFL); 2354 authctxt->authenticated = 1; 2355 if (startup_pipe != -1) { 2356 close(startup_pipe); 2357 startup_pipe = -1; 2358 } 2359 2360#ifdef SSH_AUDIT_EVENTS 2361 audit_event(SSH_AUTH_SUCCESS); 2362#endif 2363 2364#ifdef GSSAPI 2365 if (options.gss_authentication) { 2366 temporarily_use_uid(authctxt->pw); 2367 ssh_gssapi_storecreds(); 2368 restore_uid(); 2369 } 2370#endif 2371#ifdef USE_PAM 2372 if (options.use_pam) { 2373 do_pam_setcred(1); 2374 do_pam_session(); 2375 } 2376#endif 2377 2378 /* 2379 * In privilege separation, we fork another child and prepare 2380 * file descriptor passing. 2381 */ 2382 if (use_privsep) { 2383 privsep_postauth(authctxt); 2384 /* the monitor process [priv] will not return */ 2385 if (!compat20) 2386 destroy_sensitive_data(); 2387 } 2388 2389 packet_set_timeout(options.client_alive_interval, 2390 options.client_alive_count_max); 2391 2392 /* Try to send all our hostkeys to the client */ 2393 if (compat20) 2394 notify_hostkeys(active_state); 2395 2396 /* Start session. */ 2397 do_authenticated(authctxt); 2398 2399 /* The connection has been terminated. */ 2400 packet_get_bytes(&ibytes, &obytes); 2401 verbose("Transferred: sent %llu, received %llu bytes", 2402 (unsigned long long)obytes, (unsigned long long)ibytes); 2403 2404 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2405 2406#ifdef USE_PAM 2407 if (options.use_pam) 2408 finish_pam(); 2409#endif /* USE_PAM */ 2410 2411#ifdef SSH_AUDIT_EVENTS 2412 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2413#endif 2414 2415 packet_close(); 2416 2417 if (use_privsep) 2418 mm_terminate(); 2419 2420 exit(0); 2421} 2422 2423#ifdef WITH_SSH1 2424/* 2425 * Decrypt session_key_int using our private server key and private host key 2426 * (key with larger modulus first). 2427 */ 2428int 2429ssh1_session_key(BIGNUM *session_key_int) 2430{ 2431 struct ssh *ssh = active_state; /* XXX */ 2432 int rsafail = 0; 2433 2434 if (BN_cmp(sensitive_data.server_key->rsa->n, 2435 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2436 /* Server key has bigger modulus. */ 2437 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2438 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2439 SSH_KEY_BITS_RESERVED) { 2440 fatal("do_connection: %s port %d: " 2441 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2442 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 2443 BN_num_bits(sensitive_data.server_key->rsa->n), 2444 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2445 SSH_KEY_BITS_RESERVED); 2446 } 2447 if (rsa_private_decrypt(session_key_int, session_key_int, 2448 sensitive_data.server_key->rsa) != 0) 2449 rsafail++; 2450 if (rsa_private_decrypt(session_key_int, session_key_int, 2451 sensitive_data.ssh1_host_key->rsa) != 0) 2452 rsafail++; 2453 } else { 2454 /* Host key has bigger modulus (or they are equal). */ 2455 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2456 BN_num_bits(sensitive_data.server_key->rsa->n) + 2457 SSH_KEY_BITS_RESERVED) { 2458 fatal("do_connection: %s port %d: " 2459 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2460 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 2461 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2462 BN_num_bits(sensitive_data.server_key->rsa->n), 2463 SSH_KEY_BITS_RESERVED); 2464 } 2465 if (rsa_private_decrypt(session_key_int, session_key_int, 2466 sensitive_data.ssh1_host_key->rsa) != 0) 2467 rsafail++; 2468 if (rsa_private_decrypt(session_key_int, session_key_int, 2469 sensitive_data.server_key->rsa) != 0) 2470 rsafail++; 2471 } 2472 return (rsafail); 2473} 2474 2475/* 2476 * SSH1 key exchange 2477 */ 2478static void 2479do_ssh1_kex(void) 2480{ 2481 struct ssh *ssh = active_state; /* XXX */ 2482 int i, len; 2483 int rsafail = 0; 2484 BIGNUM *session_key_int, *fake_key_int, *real_key_int; 2485 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2486 u_char fake_key_bytes[4096 / 8]; 2487 size_t fake_key_len; 2488 u_char cookie[8]; 2489 u_int cipher_type, auth_mask, protocol_flags; 2490 2491 /* 2492 * Generate check bytes that the client must send back in the user 2493 * packet in order for it to be accepted; this is used to defy ip 2494 * spoofing attacks. Note that this only works against somebody 2495 * doing IP spoofing from a remote machine; any machine on the local 2496 * network can still see outgoing packets and catch the random 2497 * cookie. This only affects rhosts authentication, and this is one 2498 * of the reasons why it is inherently insecure. 2499 */ 2500 arc4random_buf(cookie, sizeof(cookie)); 2501 2502 /* 2503 * Send our public key. We include in the packet 64 bits of random 2504 * data that must be matched in the reply in order to prevent IP 2505 * spoofing. 2506 */ 2507 packet_start(SSH_SMSG_PUBLIC_KEY); 2508 for (i = 0; i < 8; i++) 2509 packet_put_char(cookie[i]); 2510 2511 /* Store our public server RSA key. */ 2512 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2513 packet_put_bignum(sensitive_data.server_key->rsa->e); 2514 packet_put_bignum(sensitive_data.server_key->rsa->n); 2515 2516 /* Store our public host RSA key. */ 2517 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2518 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2519 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2520 2521 /* Put protocol flags. */ 2522 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2523 2524 /* Declare which ciphers we support. */ 2525 packet_put_int(cipher_mask_ssh1(0)); 2526 2527 /* Declare supported authentication types. */ 2528 auth_mask = 0; 2529 if (options.rhosts_rsa_authentication) 2530 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2531 if (options.rsa_authentication) 2532 auth_mask |= 1 << SSH_AUTH_RSA; 2533 if (options.challenge_response_authentication == 1) 2534 auth_mask |= 1 << SSH_AUTH_TIS; 2535 if (options.password_authentication) 2536 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2537 packet_put_int(auth_mask); 2538 2539 /* Send the packet and wait for it to be sent. */ 2540 packet_send(); 2541 packet_write_wait(); 2542 2543 debug("Sent %d bit server key and %d bit host key.", 2544 BN_num_bits(sensitive_data.server_key->rsa->n), 2545 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2546 2547 /* Read clients reply (cipher type and session key). */ 2548 packet_read_expect(SSH_CMSG_SESSION_KEY); 2549 2550 /* Get cipher type and check whether we accept this. */ 2551 cipher_type = packet_get_char(); 2552 2553 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2554 packet_disconnect("Warning: client selects unsupported cipher."); 2555 2556 /* Get check bytes from the packet. These must match those we 2557 sent earlier with the public key packet. */ 2558 for (i = 0; i < 8; i++) 2559 if (cookie[i] != packet_get_char()) 2560 packet_disconnect("IP Spoofing check bytes do not match."); 2561 2562 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2563 2564 /* Get the encrypted integer. */ 2565 if ((real_key_int = BN_new()) == NULL) 2566 fatal("do_ssh1_kex: BN_new failed"); 2567 packet_get_bignum(real_key_int); 2568 2569 protocol_flags = packet_get_int(); 2570 packet_set_protocol_flags(protocol_flags); 2571 packet_check_eom(); 2572 2573 /* Setup a fake key in case RSA decryption fails */ 2574 if ((fake_key_int = BN_new()) == NULL) 2575 fatal("do_ssh1_kex: BN_new failed"); 2576 fake_key_len = BN_num_bytes(real_key_int); 2577 if (fake_key_len > sizeof(fake_key_bytes)) 2578 fake_key_len = sizeof(fake_key_bytes); 2579 arc4random_buf(fake_key_bytes, fake_key_len); 2580 if (BN_bin2bn(fake_key_bytes, fake_key_len, fake_key_int) == NULL) 2581 fatal("do_ssh1_kex: BN_bin2bn failed"); 2582 2583 /* Decrypt real_key_int using host/server keys */ 2584 rsafail = PRIVSEP(ssh1_session_key(real_key_int)); 2585 /* If decryption failed, use the fake key. Else, the real key. */ 2586 if (rsafail) 2587 session_key_int = fake_key_int; 2588 else 2589 session_key_int = real_key_int; 2590 2591 /* 2592 * Extract session key from the decrypted integer. The key is in the 2593 * least significant 256 bits of the integer; the first byte of the 2594 * key is in the highest bits. 2595 */ 2596 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2597 len = BN_num_bytes(session_key_int); 2598 if (len < 0 || (u_int)len > sizeof(session_key)) { 2599 error("%s: bad session key len from %s port %d: " 2600 "session_key_int %d > sizeof(session_key) %lu", __func__, 2601 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 2602 len, (u_long)sizeof(session_key)); 2603 rsafail++; 2604 } else { 2605 explicit_bzero(session_key, sizeof(session_key)); 2606 BN_bn2bin(session_key_int, 2607 session_key + sizeof(session_key) - len); 2608 2609 derive_ssh1_session_id( 2610 sensitive_data.ssh1_host_key->rsa->n, 2611 sensitive_data.server_key->rsa->n, 2612 cookie, session_id); 2613 /* 2614 * Xor the first 16 bytes of the session key with the 2615 * session id. 2616 */ 2617 for (i = 0; i < 16; i++) 2618 session_key[i] ^= session_id[i]; 2619 } 2620 2621 /* Destroy the private and public keys. No longer. */ 2622 destroy_sensitive_data(); 2623 2624 if (use_privsep) 2625 mm_ssh1_session_id(session_id); 2626 2627 /* Destroy the decrypted integer. It is no longer needed. */ 2628 BN_clear_free(real_key_int); 2629 BN_clear_free(fake_key_int); 2630 2631 /* Set the session key. From this on all communications will be encrypted. */ 2632 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2633 2634 /* Destroy our copy of the session key. It is no longer needed. */ 2635 explicit_bzero(session_key, sizeof(session_key)); 2636 2637 debug("Received session key; encryption turned on."); 2638 2639 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2640 packet_start(SSH_SMSG_SUCCESS); 2641 packet_send(); 2642 packet_write_wait(); 2643} 2644#endif 2645 2646int 2647sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, size_t *slen, 2648 const u_char *data, size_t dlen, const char *alg, u_int flag) 2649{ 2650 int r; 2651 u_int xxx_slen, xxx_dlen = dlen; 2652 2653 if (privkey) { 2654 if (PRIVSEP(key_sign(privkey, signature, &xxx_slen, data, xxx_dlen, 2655 alg) < 0)) 2656 fatal("%s: key_sign failed", __func__); 2657 if (slen) 2658 *slen = xxx_slen; 2659 } else if (use_privsep) { 2660 if (mm_key_sign(pubkey, signature, &xxx_slen, data, xxx_dlen, 2661 alg) < 0) 2662 fatal("%s: pubkey_sign failed", __func__); 2663 if (slen) 2664 *slen = xxx_slen; 2665 } else { 2666 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slen, 2667 data, dlen, alg, datafellows)) != 0) 2668 fatal("%s: ssh_agent_sign failed: %s", 2669 __func__, ssh_err(r)); 2670 } 2671 return 0; 2672} 2673 2674/* SSH2 key exchange */ 2675static void 2676do_ssh2_kex(void) 2677{ 2678 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2679 struct kex *kex; 2680 int r; 2681 2682 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2683 options.kex_algorithms); 2684 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2685 options.ciphers); 2686 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2687 options.ciphers); 2688 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2689 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2690 2691 if (options.compression == COMP_NONE) { 2692 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2693 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2694 } else if (options.compression == COMP_DELAYED) { 2695 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2696 myproposal[PROPOSAL_COMP_ALGS_STOC] = 2697 "none,zlib@openssh.com"; 2698 } 2699 2700 if (options.rekey_limit || options.rekey_interval) 2701 packet_set_rekey_limits(options.rekey_limit, 2702 (time_t)options.rekey_interval); 2703 2704 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2705 list_hostkey_types()); 2706 2707 /* start key exchange */ 2708 if ((r = kex_setup(active_state, myproposal)) != 0) 2709 fatal("kex_setup: %s", ssh_err(r)); 2710 kex = active_state->kex; 2711#ifdef WITH_OPENSSL 2712 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2713 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2714 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server; 2715 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server; 2716 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server; 2717 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2718 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2719# ifdef OPENSSL_HAS_ECC 2720 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2721# endif 2722#endif 2723 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2724 kex->server = 1; 2725 kex->client_version_string=client_version_string; 2726 kex->server_version_string=server_version_string; 2727 kex->load_host_public_key=&get_hostkey_public_by_type; 2728 kex->load_host_private_key=&get_hostkey_private_by_type; 2729 kex->host_key_index=&get_hostkey_index; 2730 kex->sign = sshd_hostkey_sign; 2731 2732 dispatch_run(DISPATCH_BLOCK, &kex->done, active_state); 2733 2734 session_id2 = kex->session_id; 2735 session_id2_len = kex->session_id_len; 2736 2737#ifdef DEBUG_KEXDH 2738 /* send 1st encrypted/maced/compressed message */ 2739 packet_start(SSH2_MSG_IGNORE); 2740 packet_put_cstring("markus"); 2741 packet_send(); 2742 packet_write_wait(); 2743#endif 2744 debug("KEX done"); 2745} 2746 2747/* server specific fatal cleanup */ 2748void 2749cleanup_exit(int i) 2750{ 2751 if (the_authctxt) { 2752 do_cleanup(the_authctxt); 2753 if (use_privsep && privsep_is_preauth && 2754 pmonitor != NULL && pmonitor->m_pid > 1) { 2755 debug("Killing privsep child %d", pmonitor->m_pid); 2756 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2757 errno != ESRCH) 2758 error("%s: kill(%d): %s", __func__, 2759 pmonitor->m_pid, strerror(errno)); 2760 } 2761 } 2762#ifdef SSH_AUDIT_EVENTS 2763 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2764 if (!use_privsep || mm_is_monitor()) 2765 audit_event(SSH_CONNECTION_ABANDON); 2766#endif 2767 _exit(i); 2768} 2769