1 /* $OpenBSD: sshd.c,v 1.465 2016/02/15 09:47:49 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("$FreeBSD$"); 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" 138 139 #ifdef LIBWRAP 140 #include <tcpd.h> 141 #include <syslog.h> 142 int allow_severity; 143 int deny_severity; 144 #endif /* LIBWRAP */ 145 146 #ifndef O_NOCTTY 147 #define O_NOCTTY 0 148 #endif 149 150 /* Re-exec fds */ 151 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 152 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 153 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 154 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 155 156 extern char *__progname; 157 158 /* Server configuration options. */ 159 ServerOptions options; 160 161 /* Name of the server configuration file. */ 162 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 163 164 /* 165 * Debug mode flag. This can be set on the command line. If debug 166 * mode is enabled, extra debugging output will be sent to the system 167 * log, the daemon will not go to background, and will exit after processing 168 * the first connection. 169 */ 170 int debug_flag = 0; 171 172 /* Flag indicating that the daemon should only test the configuration and keys. */ 173 int test_flag = 0; 174 175 /* Flag indicating that the daemon is being started from inetd. */ 176 int inetd_flag = 0; 177 178 /* Flag indicating that sshd should not detach and become a daemon. */ 179 int no_daemon_flag = 0; 180 181 /* debug goes to stderr unless inetd_flag is set */ 182 int log_stderr = 0; 183 184 /* Saved arguments to main(). */ 185 char **saved_argv; 186 int saved_argc; 187 188 /* re-exec */ 189 int rexeced_flag = 0; 190 int rexec_flag = 1; 191 int rexec_argc = 0; 192 char **rexec_argv; 193 194 /* 195 * The sockets that the server is listening; this is used in the SIGHUP 196 * signal handler. 197 */ 198 #define MAX_LISTEN_SOCKS 16 199 int listen_socks[MAX_LISTEN_SOCKS]; 200 int num_listen_socks = 0; 201 202 /* 203 * the client's version string, passed by sshd2 in compat mode. if != NULL, 204 * sshd will skip the version-number exchange 205 */ 206 char *client_version_string = NULL; 207 char *server_version_string = NULL; 208 209 /* Daemon's agent connection */ 210 int auth_sock = -1; 211 int 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 */ 221 struct { 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 */ 236 static volatile sig_atomic_t key_do_regen = 0; 237 238 /* This is set to true when a signal is received. */ 239 static volatile sig_atomic_t received_sighup = 0; 240 static volatile sig_atomic_t received_sigterm = 0; 241 242 /* session identifier, used by RSA-auth */ 243 u_char session_id[16]; 244 245 /* same for ssh2 */ 246 u_char *session_id2 = NULL; 247 u_int session_id2_len = 0; 248 249 /* record remote hostname or ip */ 250 u_int utmp_len = HOST_NAME_MAX+1; 251 252 /* options.max_startup sized array of fd ints */ 253 int *startup_pipes = NULL; 254 int startup_pipe; /* in child */ 255 256 /* variables used for privilege separation */ 257 int use_privsep = -1; 258 struct monitor *pmonitor = NULL; 259 int privsep_is_preauth = 1; 260 261 /* global authentication context */ 262 Authctxt *the_authctxt = NULL; 263 264 /* sshd_config buffer */ 265 Buffer cfg; 266 267 /* message to be displayed after login */ 268 Buffer loginmsg; 269 270 /* Unprivileged user */ 271 struct passwd *privsep_pw = NULL; 272 273 /* Prototypes for various functions defined later in this file. */ 274 void destroy_sensitive_data(void); 275 void demote_sensitive_data(void); 276 277 #ifdef WITH_SSH1 278 static void do_ssh1_kex(void); 279 #endif 280 static void do_ssh2_kex(void); 281 282 /* 283 * Close all listening sockets 284 */ 285 static void 286 close_listen_socks(void) 287 { 288 int i; 289 290 for (i = 0; i < num_listen_socks; i++) 291 close(listen_socks[i]); 292 num_listen_socks = -1; 293 } 294 295 static void 296 close_startup_pipes(void) 297 { 298 int i; 299 300 if (startup_pipes) 301 for (i = 0; i < options.max_startups; i++) 302 if (startup_pipes[i] != -1) 303 close(startup_pipes[i]); 304 } 305 306 /* 307 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 308 * the effect is to reread the configuration file (and to regenerate 309 * the server key). 310 */ 311 312 /*ARGSUSED*/ 313 static void 314 sighup_handler(int sig) 315 { 316 int save_errno = errno; 317 318 received_sighup = 1; 319 signal(SIGHUP, sighup_handler); 320 errno = save_errno; 321 } 322 323 /* 324 * Called from the main program after receiving SIGHUP. 325 * Restarts the server. 326 */ 327 static void 328 sighup_restart(void) 329 { 330 logit("Received SIGHUP; restarting."); 331 platform_pre_restart(); 332 close_listen_socks(); 333 close_startup_pipes(); 334 alarm(0); /* alarm timer persists across exec */ 335 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 336 execv(saved_argv[0], saved_argv); 337 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 338 strerror(errno)); 339 exit(1); 340 } 341 342 /* 343 * Generic signal handler for terminating signals in the master daemon. 344 */ 345 /*ARGSUSED*/ 346 static void 347 sigterm_handler(int sig) 348 { 349 received_sigterm = sig; 350 } 351 352 /* 353 * SIGCHLD handler. This is called whenever a child dies. This will then 354 * reap any zombies left by exited children. 355 */ 356 /*ARGSUSED*/ 357 static void 358 main_sigchld_handler(int sig) 359 { 360 int save_errno = errno; 361 pid_t pid; 362 int status; 363 364 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 365 (pid < 0 && errno == EINTR)) 366 ; 367 368 signal(SIGCHLD, main_sigchld_handler); 369 errno = save_errno; 370 } 371 372 /* 373 * Signal handler for the alarm after the login grace period has expired. 374 */ 375 /*ARGSUSED*/ 376 static void 377 grace_alarm_handler(int sig) 378 { 379 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 380 kill(pmonitor->m_pid, SIGALRM); 381 382 /* 383 * Try to kill any processes that we have spawned, E.g. authorized 384 * keys command helpers. 385 */ 386 if (getpgid(0) == getpid()) { 387 signal(SIGTERM, SIG_IGN); 388 kill(0, SIGTERM); 389 } 390 391 /* Log error and exit. */ 392 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 393 } 394 395 /* 396 * Signal handler for the key regeneration alarm. Note that this 397 * alarm only occurs in the daemon waiting for connections, and it does not 398 * do anything with the private key or random state before forking. 399 * Thus there should be no concurrency control/asynchronous execution 400 * problems. 401 */ 402 static void 403 generate_ephemeral_server_key(void) 404 { 405 verbose("Generating %s%d bit RSA key.", 406 sensitive_data.server_key ? "new " : "", options.server_key_bits); 407 if (sensitive_data.server_key != NULL) 408 key_free(sensitive_data.server_key); 409 sensitive_data.server_key = key_generate(KEY_RSA1, 410 options.server_key_bits); 411 verbose("RSA key generation complete."); 412 413 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 414 } 415 416 /*ARGSUSED*/ 417 static void 418 key_regeneration_alarm(int sig) 419 { 420 int save_errno = errno; 421 422 signal(SIGALRM, SIG_DFL); 423 errno = save_errno; 424 key_do_regen = 1; 425 } 426 427 static void 428 sshd_exchange_identification(int sock_in, int sock_out) 429 { 430 u_int i; 431 int mismatch; 432 int remote_major, remote_minor; 433 int major, minor; 434 char *s, *newline = "\n"; 435 char buf[256]; /* Must not be larger than remote_version. */ 436 char remote_version[256]; /* Must be at least as big as buf. */ 437 438 if ((options.protocol & SSH_PROTO_1) && 439 (options.protocol & SSH_PROTO_2)) { 440 major = PROTOCOL_MAJOR_1; 441 minor = 99; 442 } else if (options.protocol & SSH_PROTO_2) { 443 major = PROTOCOL_MAJOR_2; 444 minor = PROTOCOL_MINOR_2; 445 newline = "\r\n"; 446 } else { 447 major = PROTOCOL_MAJOR_1; 448 minor = PROTOCOL_MINOR_1; 449 } 450 451 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s", 452 major, minor, SSH_VERSION, 453 *options.version_addendum == '\0' ? "" : " ", 454 options.version_addendum, newline); 455 456 /* Send our protocol version identification. */ 457 if (atomicio(vwrite, sock_out, server_version_string, 458 strlen(server_version_string)) 459 != strlen(server_version_string)) { 460 logit("Could not write ident string to %s", get_remote_ipaddr()); 461 cleanup_exit(255); 462 } 463 464 /* Read other sides version identification. */ 465 memset(buf, 0, sizeof(buf)); 466 for (i = 0; i < sizeof(buf) - 1; i++) { 467 if (atomicio(read, sock_in, &buf[i], 1) != 1) { 468 logit("Did not receive identification string from %s", 469 get_remote_ipaddr()); 470 cleanup_exit(255); 471 } 472 if (buf[i] == '\r') { 473 buf[i] = 0; 474 /* Kludge for F-Secure Macintosh < 1.0.2 */ 475 if (i == 12 && 476 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 477 break; 478 continue; 479 } 480 if (buf[i] == '\n') { 481 buf[i] = 0; 482 break; 483 } 484 } 485 buf[sizeof(buf) - 1] = 0; 486 client_version_string = xstrdup(buf); 487 488 /* 489 * Check that the versions match. In future this might accept 490 * several versions and set appropriate flags to handle them. 491 */ 492 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 493 &remote_major, &remote_minor, remote_version) != 3) { 494 s = "Protocol mismatch.\n"; 495 (void) atomicio(vwrite, sock_out, s, strlen(s)); 496 logit("Bad protocol version identification '%.100s' " 497 "from %s port %d", client_version_string, 498 get_remote_ipaddr(), get_remote_port()); 499 close(sock_in); 500 close(sock_out); 501 cleanup_exit(255); 502 } 503 debug("Client protocol version %d.%d; client software version %.100s", 504 remote_major, remote_minor, remote_version); 505 506 active_state->compat = compat_datafellows(remote_version); 507 508 if ((datafellows & SSH_BUG_PROBE) != 0) { 509 logit("probed from %s with %s. Don't panic.", 510 get_remote_ipaddr(), client_version_string); 511 cleanup_exit(255); 512 } 513 if ((datafellows & SSH_BUG_SCANNER) != 0) { 514 logit("scanned from %s with %s. Don't panic.", 515 get_remote_ipaddr(), client_version_string); 516 cleanup_exit(255); 517 } 518 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) { 519 logit("Client version \"%.100s\" uses unsafe RSA signature " 520 "scheme; disabling use of RSA keys", remote_version); 521 } 522 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) { 523 fatal("Client version \"%.100s\" uses unsafe key agreement; " 524 "refusing connection", remote_version); 525 } 526 527 mismatch = 0; 528 switch (remote_major) { 529 case 1: 530 if (remote_minor == 99) { 531 if (options.protocol & SSH_PROTO_2) 532 enable_compat20(); 533 else 534 mismatch = 1; 535 break; 536 } 537 if (!(options.protocol & SSH_PROTO_1)) { 538 mismatch = 1; 539 break; 540 } 541 if (remote_minor < 3) { 542 packet_disconnect("Your ssh version is too old and " 543 "is no longer supported. Please install a newer version."); 544 } else if (remote_minor == 3) { 545 /* note that this disables agent-forwarding */ 546 enable_compat13(); 547 } 548 break; 549 case 2: 550 if (options.protocol & SSH_PROTO_2) { 551 enable_compat20(); 552 break; 553 } 554 /* FALLTHROUGH */ 555 default: 556 mismatch = 1; 557 break; 558 } 559 chop(server_version_string); 560 debug("Local version string %.200s", server_version_string); 561 562 if (mismatch) { 563 s = "Protocol major versions differ.\n"; 564 (void) atomicio(vwrite, sock_out, s, strlen(s)); 565 close(sock_in); 566 close(sock_out); 567 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 568 get_remote_ipaddr(), 569 server_version_string, client_version_string); 570 cleanup_exit(255); 571 } 572 } 573 574 /* Destroy the host and server keys. They will no longer be needed. */ 575 void 576 destroy_sensitive_data(void) 577 { 578 int i; 579 580 if (sensitive_data.server_key) { 581 key_free(sensitive_data.server_key); 582 sensitive_data.server_key = NULL; 583 } 584 for (i = 0; i < options.num_host_key_files; i++) { 585 if (sensitive_data.host_keys[i]) { 586 key_free(sensitive_data.host_keys[i]); 587 sensitive_data.host_keys[i] = NULL; 588 } 589 if (sensitive_data.host_certificates[i]) { 590 key_free(sensitive_data.host_certificates[i]); 591 sensitive_data.host_certificates[i] = NULL; 592 } 593 } 594 sensitive_data.ssh1_host_key = NULL; 595 explicit_bzero(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 596 } 597 598 /* Demote private to public keys for network child */ 599 void 600 demote_sensitive_data(void) 601 { 602 Key *tmp; 603 int i; 604 605 if (sensitive_data.server_key) { 606 tmp = key_demote(sensitive_data.server_key); 607 key_free(sensitive_data.server_key); 608 sensitive_data.server_key = tmp; 609 } 610 611 for (i = 0; i < options.num_host_key_files; i++) { 612 if (sensitive_data.host_keys[i]) { 613 tmp = key_demote(sensitive_data.host_keys[i]); 614 key_free(sensitive_data.host_keys[i]); 615 sensitive_data.host_keys[i] = tmp; 616 if (tmp->type == KEY_RSA1) 617 sensitive_data.ssh1_host_key = tmp; 618 } 619 /* Certs do not need demotion */ 620 } 621 622 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 623 } 624 625 static void 626 privsep_preauth_child(void) 627 { 628 u_int32_t rnd[256]; 629 gid_t gidset[1]; 630 631 /* Enable challenge-response authentication for privilege separation */ 632 privsep_challenge_enable(); 633 634 #ifdef GSSAPI 635 /* Cache supported mechanism OIDs for later use */ 636 if (options.gss_authentication) 637 ssh_gssapi_prepare_supported_oids(); 638 #endif 639 640 arc4random_stir(); 641 arc4random_buf(rnd, sizeof(rnd)); 642 #ifdef WITH_OPENSSL 643 RAND_seed(rnd, sizeof(rnd)); 644 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 645 fatal("%s: RAND_bytes failed", __func__); 646 #endif 647 explicit_bzero(rnd, sizeof(rnd)); 648 649 /* Demote the private keys to public keys. */ 650 demote_sensitive_data(); 651 652 /* Demote the child */ 653 if (getuid() == 0 || geteuid() == 0) { 654 /* Change our root directory */ 655 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 656 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 657 strerror(errno)); 658 if (chdir("/") == -1) 659 fatal("chdir(\"/\"): %s", strerror(errno)); 660 661 /* Drop our privileges */ 662 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 663 (u_int)privsep_pw->pw_gid); 664 gidset[0] = privsep_pw->pw_gid; 665 if (setgroups(1, gidset) < 0) 666 fatal("setgroups: %.100s", strerror(errno)); 667 permanently_set_uid(privsep_pw); 668 } 669 } 670 671 static int 672 privsep_preauth(Authctxt *authctxt) 673 { 674 int status, r; 675 pid_t pid; 676 struct ssh_sandbox *box = NULL; 677 678 /* Set up unprivileged child process to deal with network data */ 679 pmonitor = monitor_init(); 680 /* Store a pointer to the kex for later rekeying */ 681 pmonitor->m_pkex = &active_state->kex; 682 683 if (use_privsep == PRIVSEP_ON) 684 box = ssh_sandbox_init(pmonitor); 685 pid = fork(); 686 if (pid == -1) { 687 fatal("fork of unprivileged child failed"); 688 } else if (pid != 0) { 689 debug2("Network child is on pid %ld", (long)pid); 690 691 pmonitor->m_pid = pid; 692 if (have_agent) { 693 r = ssh_get_authentication_socket(&auth_sock); 694 if (r != 0) { 695 error("Could not get agent socket: %s", 696 ssh_err(r)); 697 have_agent = 0; 698 } 699 } 700 if (box != NULL) 701 ssh_sandbox_parent_preauth(box, pid); 702 monitor_child_preauth(authctxt, pmonitor); 703 704 /* Sync memory */ 705 monitor_sync(pmonitor); 706 707 /* Wait for the child's exit status */ 708 while (waitpid(pid, &status, 0) < 0) { 709 if (errno == EINTR) 710 continue; 711 pmonitor->m_pid = -1; 712 fatal("%s: waitpid: %s", __func__, strerror(errno)); 713 } 714 privsep_is_preauth = 0; 715 pmonitor->m_pid = -1; 716 if (WIFEXITED(status)) { 717 if (WEXITSTATUS(status) != 0) 718 fatal("%s: preauth child exited with status %d", 719 __func__, WEXITSTATUS(status)); 720 } else if (WIFSIGNALED(status)) 721 fatal("%s: preauth child terminated by signal %d", 722 __func__, WTERMSIG(status)); 723 if (box != NULL) 724 ssh_sandbox_parent_finish(box); 725 return 1; 726 } else { 727 /* child */ 728 close(pmonitor->m_sendfd); 729 close(pmonitor->m_log_recvfd); 730 731 /* Arrange for logging to be sent to the monitor */ 732 set_log_handler(mm_log_handler, pmonitor); 733 734 privsep_preauth_child(); 735 setproctitle("%s", "[net]"); 736 if (box != NULL) 737 ssh_sandbox_child(box); 738 739 return 0; 740 } 741 } 742 743 static void 744 privsep_postauth(Authctxt *authctxt) 745 { 746 u_int32_t rnd[256]; 747 748 #ifdef DISABLE_FD_PASSING 749 if (1) { 750 #else 751 if (authctxt->pw->pw_uid == 0 || options.use_login) { 752 #endif 753 /* File descriptor passing is broken or root login */ 754 use_privsep = 0; 755 goto skip; 756 } 757 758 /* New socket pair */ 759 monitor_reinit(pmonitor); 760 761 pmonitor->m_pid = fork(); 762 if (pmonitor->m_pid == -1) 763 fatal("fork of unprivileged child failed"); 764 else if (pmonitor->m_pid != 0) { 765 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 766 buffer_clear(&loginmsg); 767 monitor_child_postauth(pmonitor); 768 769 /* NEVERREACHED */ 770 exit(0); 771 } 772 773 /* child */ 774 775 close(pmonitor->m_sendfd); 776 pmonitor->m_sendfd = -1; 777 778 /* Demote the private keys to public keys. */ 779 demote_sensitive_data(); 780 781 arc4random_stir(); 782 arc4random_buf(rnd, sizeof(rnd)); 783 #ifdef WITH_OPENSSL 784 RAND_seed(rnd, sizeof(rnd)); 785 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 786 fatal("%s: RAND_bytes failed", __func__); 787 #endif 788 explicit_bzero(rnd, sizeof(rnd)); 789 790 /* Drop privileges */ 791 do_setusercontext(authctxt->pw); 792 793 skip: 794 /* It is safe now to apply the key state */ 795 monitor_apply_keystate(pmonitor); 796 797 /* 798 * Tell the packet layer that authentication was successful, since 799 * this information is not part of the key state. 800 */ 801 packet_set_authenticated(); 802 } 803 804 static char * 805 list_hostkey_types(void) 806 { 807 Buffer b; 808 const char *p; 809 char *ret; 810 int i; 811 Key *key; 812 813 buffer_init(&b); 814 for (i = 0; i < options.num_host_key_files; i++) { 815 key = sensitive_data.host_keys[i]; 816 if (key == NULL) 817 key = sensitive_data.host_pubkeys[i]; 818 if (key == NULL || key->type == KEY_RSA1) 819 continue; 820 /* Check that the key is accepted in HostkeyAlgorithms */ 821 if (match_pattern_list(sshkey_ssh_name(key), 822 options.hostkeyalgorithms, 0) != 1) { 823 debug3("%s: %s key not permitted by HostkeyAlgorithms", 824 __func__, sshkey_ssh_name(key)); 825 continue; 826 } 827 switch (key->type) { 828 case KEY_RSA: 829 case KEY_DSA: 830 case KEY_ECDSA: 831 case KEY_ED25519: 832 if (buffer_len(&b) > 0) 833 buffer_append(&b, ",", 1); 834 p = key_ssh_name(key); 835 buffer_append(&b, p, strlen(p)); 836 837 /* for RSA we also support SHA2 signatures */ 838 if (key->type == KEY_RSA) { 839 p = ",rsa-sha2-512,rsa-sha2-256"; 840 buffer_append(&b, p, strlen(p)); 841 } 842 break; 843 } 844 /* If the private key has a cert peer, then list that too */ 845 key = sensitive_data.host_certificates[i]; 846 if (key == NULL) 847 continue; 848 switch (key->type) { 849 case KEY_RSA_CERT: 850 case KEY_DSA_CERT: 851 case KEY_ECDSA_CERT: 852 case KEY_ED25519_CERT: 853 if (buffer_len(&b) > 0) 854 buffer_append(&b, ",", 1); 855 p = key_ssh_name(key); 856 buffer_append(&b, p, strlen(p)); 857 break; 858 } 859 } 860 buffer_append(&b, "\0", 1); 861 ret = xstrdup(buffer_ptr(&b)); 862 buffer_free(&b); 863 debug("list_hostkey_types: %s", ret); 864 return ret; 865 } 866 867 static Key * 868 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 869 { 870 int i; 871 Key *key; 872 873 for (i = 0; i < options.num_host_key_files; i++) { 874 switch (type) { 875 case KEY_RSA_CERT: 876 case KEY_DSA_CERT: 877 case KEY_ECDSA_CERT: 878 case KEY_ED25519_CERT: 879 key = sensitive_data.host_certificates[i]; 880 break; 881 default: 882 key = sensitive_data.host_keys[i]; 883 if (key == NULL && !need_private) 884 key = sensitive_data.host_pubkeys[i]; 885 break; 886 } 887 if (key != NULL && key->type == type && 888 (key->type != KEY_ECDSA || key->ecdsa_nid == nid)) 889 return need_private ? 890 sensitive_data.host_keys[i] : key; 891 } 892 return NULL; 893 } 894 895 Key * 896 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 897 { 898 return get_hostkey_by_type(type, nid, 0, ssh); 899 } 900 901 Key * 902 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 903 { 904 return get_hostkey_by_type(type, nid, 1, ssh); 905 } 906 907 Key * 908 get_hostkey_by_index(int ind) 909 { 910 if (ind < 0 || ind >= options.num_host_key_files) 911 return (NULL); 912 return (sensitive_data.host_keys[ind]); 913 } 914 915 Key * 916 get_hostkey_public_by_index(int ind, struct ssh *ssh) 917 { 918 if (ind < 0 || ind >= options.num_host_key_files) 919 return (NULL); 920 return (sensitive_data.host_pubkeys[ind]); 921 } 922 923 int 924 get_hostkey_index(Key *key, int compare, struct ssh *ssh) 925 { 926 int i; 927 928 for (i = 0; i < options.num_host_key_files; i++) { 929 if (key_is_cert(key)) { 930 if (key == sensitive_data.host_certificates[i] || 931 (compare && sensitive_data.host_certificates[i] && 932 sshkey_equal(key, 933 sensitive_data.host_certificates[i]))) 934 return (i); 935 } else { 936 if (key == sensitive_data.host_keys[i] || 937 (compare && sensitive_data.host_keys[i] && 938 sshkey_equal(key, sensitive_data.host_keys[i]))) 939 return (i); 940 if (key == sensitive_data.host_pubkeys[i] || 941 (compare && sensitive_data.host_pubkeys[i] && 942 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 943 return (i); 944 } 945 } 946 return (-1); 947 } 948 949 /* Inform the client of all hostkeys */ 950 static void 951 notify_hostkeys(struct ssh *ssh) 952 { 953 struct sshbuf *buf; 954 struct sshkey *key; 955 int i, nkeys, r; 956 char *fp; 957 958 /* Some clients cannot cope with the hostkeys message, skip those. */ 959 if (datafellows & SSH_BUG_HOSTKEYS) 960 return; 961 962 if ((buf = sshbuf_new()) == NULL) 963 fatal("%s: sshbuf_new", __func__); 964 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 965 key = get_hostkey_public_by_index(i, ssh); 966 if (key == NULL || key->type == KEY_UNSPEC || 967 key->type == KEY_RSA1 || sshkey_is_cert(key)) 968 continue; 969 fp = sshkey_fingerprint(key, options.fingerprint_hash, 970 SSH_FP_DEFAULT); 971 debug3("%s: key %d: %s %s", __func__, i, 972 sshkey_ssh_name(key), fp); 973 free(fp); 974 if (nkeys == 0) { 975 packet_start(SSH2_MSG_GLOBAL_REQUEST); 976 packet_put_cstring("hostkeys-00@openssh.com"); 977 packet_put_char(0); /* want-reply */ 978 } 979 sshbuf_reset(buf); 980 if ((r = sshkey_putb(key, buf)) != 0) 981 fatal("%s: couldn't put hostkey %d: %s", 982 __func__, i, ssh_err(r)); 983 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf)); 984 nkeys++; 985 } 986 debug3("%s: sent %d hostkeys", __func__, nkeys); 987 if (nkeys == 0) 988 fatal("%s: no hostkeys", __func__); 989 packet_send(); 990 sshbuf_free(buf); 991 } 992 993 /* 994 * returns 1 if connection should be dropped, 0 otherwise. 995 * dropping starts at connection #max_startups_begin with a probability 996 * of (max_startups_rate/100). the probability increases linearly until 997 * all connections are dropped for startups > max_startups 998 */ 999 static int 1000 drop_connection(int startups) 1001 { 1002 int p, r; 1003 1004 if (startups < options.max_startups_begin) 1005 return 0; 1006 if (startups >= options.max_startups) 1007 return 1; 1008 if (options.max_startups_rate == 100) 1009 return 1; 1010 1011 p = 100 - options.max_startups_rate; 1012 p *= startups - options.max_startups_begin; 1013 p /= options.max_startups - options.max_startups_begin; 1014 p += options.max_startups_rate; 1015 r = arc4random_uniform(100); 1016 1017 debug("drop_connection: p %d, r %d", p, r); 1018 return (r < p) ? 1 : 0; 1019 } 1020 1021 static void 1022 usage(void) 1023 { 1024 if (options.version_addendum && *options.version_addendum != '\0') 1025 fprintf(stderr, "%s %s, %s\n", 1026 SSH_RELEASE, 1027 options.version_addendum, OPENSSL_VERSION); 1028 else 1029 fprintf(stderr, "%s, %s\n", 1030 SSH_RELEASE, OPENSSL_VERSION); 1031 fprintf(stderr, 1032 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 1033 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 1034 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port]\n" 1035 " [-u len]\n" 1036 ); 1037 exit(1); 1038 } 1039 1040 static void 1041 send_rexec_state(int fd, Buffer *conf) 1042 { 1043 Buffer m; 1044 1045 debug3("%s: entering fd = %d config len %d", __func__, fd, 1046 buffer_len(conf)); 1047 1048 /* 1049 * Protocol from reexec master to child: 1050 * string configuration 1051 * u_int ephemeral_key_follows 1052 * bignum e (only if ephemeral_key_follows == 1) 1053 * bignum n " 1054 * bignum d " 1055 * bignum iqmp " 1056 * bignum p " 1057 * bignum q " 1058 * string rngseed (only if OpenSSL is not self-seeded) 1059 */ 1060 buffer_init(&m); 1061 buffer_put_cstring(&m, buffer_ptr(conf)); 1062 1063 #ifdef WITH_SSH1 1064 if (sensitive_data.server_key != NULL && 1065 sensitive_data.server_key->type == KEY_RSA1) { 1066 buffer_put_int(&m, 1); 1067 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 1068 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 1069 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 1070 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 1071 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 1072 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 1073 } else 1074 #endif 1075 buffer_put_int(&m, 0); 1076 1077 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 1078 rexec_send_rng_seed(&m); 1079 #endif 1080 1081 if (ssh_msg_send(fd, 0, &m) == -1) 1082 fatal("%s: ssh_msg_send failed", __func__); 1083 1084 buffer_free(&m); 1085 1086 debug3("%s: done", __func__); 1087 } 1088 1089 static void 1090 recv_rexec_state(int fd, Buffer *conf) 1091 { 1092 Buffer m; 1093 char *cp; 1094 u_int len; 1095 1096 debug3("%s: entering fd = %d", __func__, fd); 1097 1098 buffer_init(&m); 1099 1100 if (ssh_msg_recv(fd, &m) == -1) 1101 fatal("%s: ssh_msg_recv failed", __func__); 1102 if (buffer_get_char(&m) != 0) 1103 fatal("%s: rexec version mismatch", __func__); 1104 1105 cp = buffer_get_string(&m, &len); 1106 if (conf != NULL) 1107 buffer_append(conf, cp, len + 1); 1108 free(cp); 1109 1110 if (buffer_get_int(&m)) { 1111 #ifdef WITH_SSH1 1112 if (sensitive_data.server_key != NULL) 1113 key_free(sensitive_data.server_key); 1114 sensitive_data.server_key = key_new_private(KEY_RSA1); 1115 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 1116 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 1117 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 1118 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 1119 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 1120 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 1121 if (rsa_generate_additional_parameters( 1122 sensitive_data.server_key->rsa) != 0) 1123 fatal("%s: rsa_generate_additional_parameters " 1124 "error", __func__); 1125 #endif 1126 } 1127 1128 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 1129 rexec_recv_rng_seed(&m); 1130 #endif 1131 1132 buffer_free(&m); 1133 1134 debug3("%s: done", __func__); 1135 } 1136 1137 /* Accept a connection from inetd */ 1138 static void 1139 server_accept_inetd(int *sock_in, int *sock_out) 1140 { 1141 int fd; 1142 1143 startup_pipe = -1; 1144 if (rexeced_flag) { 1145 close(REEXEC_CONFIG_PASS_FD); 1146 *sock_in = *sock_out = dup(STDIN_FILENO); 1147 if (!debug_flag) { 1148 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1149 close(REEXEC_STARTUP_PIPE_FD); 1150 } 1151 } else { 1152 *sock_in = dup(STDIN_FILENO); 1153 *sock_out = dup(STDOUT_FILENO); 1154 } 1155 /* 1156 * We intentionally do not close the descriptors 0, 1, and 2 1157 * as our code for setting the descriptors won't work if 1158 * ttyfd happens to be one of those. 1159 */ 1160 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1161 dup2(fd, STDIN_FILENO); 1162 dup2(fd, STDOUT_FILENO); 1163 if (!log_stderr) 1164 dup2(fd, STDERR_FILENO); 1165 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1166 close(fd); 1167 } 1168 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1169 } 1170 1171 /* 1172 * Listen for TCP connections 1173 */ 1174 static void 1175 server_listen(void) 1176 { 1177 int ret, listen_sock, on = 1; 1178 struct addrinfo *ai; 1179 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1180 int socksize; 1181 socklen_t len; 1182 1183 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1184 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1185 continue; 1186 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1187 fatal("Too many listen sockets. " 1188 "Enlarge MAX_LISTEN_SOCKS"); 1189 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1190 ntop, sizeof(ntop), strport, sizeof(strport), 1191 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1192 error("getnameinfo failed: %.100s", 1193 ssh_gai_strerror(ret)); 1194 continue; 1195 } 1196 /* Create socket for listening. */ 1197 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1198 ai->ai_protocol); 1199 if (listen_sock < 0) { 1200 /* kernel may not support ipv6 */ 1201 verbose("socket: %.100s", strerror(errno)); 1202 continue; 1203 } 1204 if (set_nonblock(listen_sock) == -1) { 1205 close(listen_sock); 1206 continue; 1207 } 1208 /* 1209 * Set socket options. 1210 * Allow local port reuse in TIME_WAIT. 1211 */ 1212 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1213 &on, sizeof(on)) == -1) 1214 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1215 1216 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1217 if (ai->ai_family == AF_INET6) 1218 sock_set_v6only(listen_sock); 1219 1220 debug("Bind to port %s on %s.", strport, ntop); 1221 1222 len = sizeof(socksize); 1223 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len); 1224 debug("Server TCP RWIN socket size: %d", socksize); 1225 1226 /* Bind the socket to the desired port. */ 1227 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1228 error("Bind to port %s on %s failed: %.200s.", 1229 strport, ntop, strerror(errno)); 1230 close(listen_sock); 1231 continue; 1232 } 1233 listen_socks[num_listen_socks] = listen_sock; 1234 num_listen_socks++; 1235 1236 /* Start listening on the port. */ 1237 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1238 fatal("listen on [%s]:%s: %.100s", 1239 ntop, strport, strerror(errno)); 1240 logit("Server listening on %s port %s.", ntop, strport); 1241 } 1242 freeaddrinfo(options.listen_addrs); 1243 1244 if (!num_listen_socks) 1245 fatal("Cannot bind any address."); 1246 } 1247 1248 /* 1249 * The main TCP accept loop. Note that, for the non-debug case, returns 1250 * from this function are in a forked subprocess. 1251 */ 1252 static void 1253 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1254 { 1255 fd_set *fdset; 1256 int i, j, ret, maxfd; 1257 int key_used = 0, startups = 0; 1258 int startup_p[2] = { -1 , -1 }; 1259 struct sockaddr_storage from; 1260 socklen_t fromlen; 1261 pid_t pid; 1262 u_char rnd[256]; 1263 1264 /* setup fd set for accept */ 1265 fdset = NULL; 1266 maxfd = 0; 1267 for (i = 0; i < num_listen_socks; i++) 1268 if (listen_socks[i] > maxfd) 1269 maxfd = listen_socks[i]; 1270 /* pipes connected to unauthenticated childs */ 1271 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1272 for (i = 0; i < options.max_startups; i++) 1273 startup_pipes[i] = -1; 1274 1275 /* 1276 * Stay listening for connections until the system crashes or 1277 * the daemon is killed with a signal. 1278 */ 1279 for (;;) { 1280 if (received_sighup) 1281 sighup_restart(); 1282 free(fdset); 1283 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1284 sizeof(fd_mask)); 1285 1286 for (i = 0; i < num_listen_socks; i++) 1287 FD_SET(listen_socks[i], fdset); 1288 for (i = 0; i < options.max_startups; i++) 1289 if (startup_pipes[i] != -1) 1290 FD_SET(startup_pipes[i], fdset); 1291 1292 /* Wait in select until there is a connection. */ 1293 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1294 if (ret < 0 && errno != EINTR) 1295 error("select: %.100s", strerror(errno)); 1296 if (received_sigterm) { 1297 logit("Received signal %d; terminating.", 1298 (int) received_sigterm); 1299 close_listen_socks(); 1300 if (options.pid_file != NULL) 1301 unlink(options.pid_file); 1302 exit(received_sigterm == SIGTERM ? 0 : 255); 1303 } 1304 if (key_used && key_do_regen) { 1305 generate_ephemeral_server_key(); 1306 key_used = 0; 1307 key_do_regen = 0; 1308 } 1309 if (ret < 0) 1310 continue; 1311 1312 for (i = 0; i < options.max_startups; i++) 1313 if (startup_pipes[i] != -1 && 1314 FD_ISSET(startup_pipes[i], fdset)) { 1315 /* 1316 * the read end of the pipe is ready 1317 * if the child has closed the pipe 1318 * after successful authentication 1319 * or if the child has died 1320 */ 1321 close(startup_pipes[i]); 1322 startup_pipes[i] = -1; 1323 startups--; 1324 } 1325 for (i = 0; i < num_listen_socks; i++) { 1326 if (!FD_ISSET(listen_socks[i], fdset)) 1327 continue; 1328 fromlen = sizeof(from); 1329 *newsock = accept(listen_socks[i], 1330 (struct sockaddr *)&from, &fromlen); 1331 if (*newsock < 0) { 1332 if (errno != EINTR && errno != EWOULDBLOCK && 1333 errno != ECONNABORTED && errno != EAGAIN) 1334 error("accept: %.100s", 1335 strerror(errno)); 1336 if (errno == EMFILE || errno == ENFILE) 1337 usleep(100 * 1000); 1338 continue; 1339 } 1340 if (unset_nonblock(*newsock) == -1) { 1341 close(*newsock); 1342 continue; 1343 } 1344 if (drop_connection(startups) == 1) { 1345 debug("drop connection #%d", startups); 1346 close(*newsock); 1347 continue; 1348 } 1349 if (pipe(startup_p) == -1) { 1350 close(*newsock); 1351 continue; 1352 } 1353 1354 if (rexec_flag && socketpair(AF_UNIX, 1355 SOCK_STREAM, 0, config_s) == -1) { 1356 error("reexec socketpair: %s", 1357 strerror(errno)); 1358 close(*newsock); 1359 close(startup_p[0]); 1360 close(startup_p[1]); 1361 continue; 1362 } 1363 1364 for (j = 0; j < options.max_startups; j++) 1365 if (startup_pipes[j] == -1) { 1366 startup_pipes[j] = startup_p[0]; 1367 if (maxfd < startup_p[0]) 1368 maxfd = startup_p[0]; 1369 startups++; 1370 break; 1371 } 1372 1373 /* 1374 * Got connection. Fork a child to handle it, unless 1375 * we are in debugging mode. 1376 */ 1377 if (debug_flag) { 1378 /* 1379 * In debugging mode. Close the listening 1380 * socket, and start processing the 1381 * connection without forking. 1382 */ 1383 debug("Server will not fork when running in debugging mode."); 1384 close_listen_socks(); 1385 *sock_in = *newsock; 1386 *sock_out = *newsock; 1387 close(startup_p[0]); 1388 close(startup_p[1]); 1389 startup_pipe = -1; 1390 pid = getpid(); 1391 if (rexec_flag) { 1392 send_rexec_state(config_s[0], 1393 &cfg); 1394 close(config_s[0]); 1395 } 1396 break; 1397 } 1398 1399 /* 1400 * Normal production daemon. Fork, and have 1401 * the child process the connection. The 1402 * parent continues listening. 1403 */ 1404 platform_pre_fork(); 1405 if ((pid = fork()) == 0) { 1406 /* 1407 * Child. Close the listening and 1408 * max_startup sockets. Start using 1409 * the accepted socket. Reinitialize 1410 * logging (since our pid has changed). 1411 * We break out of the loop to handle 1412 * the connection. 1413 */ 1414 platform_post_fork_child(); 1415 startup_pipe = startup_p[1]; 1416 close_startup_pipes(); 1417 close_listen_socks(); 1418 *sock_in = *newsock; 1419 *sock_out = *newsock; 1420 log_init(__progname, 1421 options.log_level, 1422 options.log_facility, 1423 log_stderr); 1424 if (rexec_flag) 1425 close(config_s[0]); 1426 break; 1427 } 1428 1429 /* Parent. Stay in the loop. */ 1430 platform_post_fork_parent(pid); 1431 if (pid < 0) 1432 error("fork: %.100s", strerror(errno)); 1433 else 1434 debug("Forked child %ld.", (long)pid); 1435 1436 close(startup_p[1]); 1437 1438 if (rexec_flag) { 1439 send_rexec_state(config_s[0], &cfg); 1440 close(config_s[0]); 1441 close(config_s[1]); 1442 } 1443 1444 /* 1445 * Mark that the key has been used (it 1446 * was "given" to the child). 1447 */ 1448 if ((options.protocol & SSH_PROTO_1) && 1449 key_used == 0) { 1450 /* Schedule server key regeneration alarm. */ 1451 signal(SIGALRM, key_regeneration_alarm); 1452 alarm(options.key_regeneration_time); 1453 key_used = 1; 1454 } 1455 1456 close(*newsock); 1457 1458 /* 1459 * Ensure that our random state differs 1460 * from that of the child 1461 */ 1462 arc4random_stir(); 1463 arc4random_buf(rnd, sizeof(rnd)); 1464 #ifdef WITH_OPENSSL 1465 RAND_seed(rnd, sizeof(rnd)); 1466 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 1467 fatal("%s: RAND_bytes failed", __func__); 1468 #endif 1469 explicit_bzero(rnd, sizeof(rnd)); 1470 } 1471 1472 /* child process check (or debug mode) */ 1473 if (num_listen_socks < 0) 1474 break; 1475 } 1476 } 1477 1478 1479 /* 1480 * Main program for the daemon. 1481 */ 1482 int 1483 main(int ac, char **av) 1484 { 1485 extern char *optarg; 1486 extern int optind; 1487 int r, opt, i, j, on = 1; 1488 int sock_in = -1, sock_out = -1, newsock = -1; 1489 const char *remote_ip; 1490 int remote_port; 1491 char *fp, *line, *laddr, *logfile = NULL; 1492 int config_s[2] = { -1 , -1 }; 1493 u_int n; 1494 u_int64_t ibytes, obytes; 1495 mode_t new_umask; 1496 Key *key; 1497 Key *pubkey; 1498 int keytype; 1499 Authctxt *authctxt; 1500 struct connection_info *connection_info = get_connection_info(0, 0); 1501 1502 ssh_malloc_init(); /* must be called before any mallocs */ 1503 1504 #ifdef HAVE_SECUREWARE 1505 (void)set_auth_parameters(ac, av); 1506 #endif 1507 __progname = ssh_get_progname(av[0]); 1508 1509 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1510 saved_argc = ac; 1511 rexec_argc = ac; 1512 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1513 for (i = 0; i < ac; i++) 1514 saved_argv[i] = xstrdup(av[i]); 1515 saved_argv[i] = NULL; 1516 1517 #ifndef HAVE_SETPROCTITLE 1518 /* Prepare for later setproctitle emulation */ 1519 compat_init_setproctitle(ac, av); 1520 av = saved_argv; 1521 #endif 1522 1523 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1524 debug("setgroups(): %.200s", strerror(errno)); 1525 1526 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1527 sanitise_stdfd(); 1528 1529 /* Initialize configuration options to their default values. */ 1530 initialize_server_options(&options); 1531 1532 /* Parse command-line arguments. */ 1533 while ((opt = getopt(ac, av, 1534 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1535 switch (opt) { 1536 case '4': 1537 options.address_family = AF_INET; 1538 break; 1539 case '6': 1540 options.address_family = AF_INET6; 1541 break; 1542 case 'f': 1543 config_file_name = optarg; 1544 break; 1545 case 'c': 1546 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1547 fprintf(stderr, "too many host certificates.\n"); 1548 exit(1); 1549 } 1550 options.host_cert_files[options.num_host_cert_files++] = 1551 derelativise_path(optarg); 1552 break; 1553 case 'd': 1554 if (debug_flag == 0) { 1555 debug_flag = 1; 1556 options.log_level = SYSLOG_LEVEL_DEBUG1; 1557 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1558 options.log_level++; 1559 break; 1560 case 'D': 1561 no_daemon_flag = 1; 1562 break; 1563 case 'E': 1564 logfile = optarg; 1565 /* FALLTHROUGH */ 1566 case 'e': 1567 log_stderr = 1; 1568 break; 1569 case 'i': 1570 inetd_flag = 1; 1571 break; 1572 case 'r': 1573 rexec_flag = 0; 1574 break; 1575 case 'R': 1576 rexeced_flag = 1; 1577 inetd_flag = 1; 1578 break; 1579 case 'Q': 1580 /* ignored */ 1581 break; 1582 case 'q': 1583 options.log_level = SYSLOG_LEVEL_QUIET; 1584 break; 1585 case 'b': 1586 options.server_key_bits = (int)strtonum(optarg, 256, 1587 32768, NULL); 1588 break; 1589 case 'p': 1590 options.ports_from_cmdline = 1; 1591 if (options.num_ports >= MAX_PORTS) { 1592 fprintf(stderr, "too many ports.\n"); 1593 exit(1); 1594 } 1595 options.ports[options.num_ports++] = a2port(optarg); 1596 if (options.ports[options.num_ports-1] <= 0) { 1597 fprintf(stderr, "Bad port number.\n"); 1598 exit(1); 1599 } 1600 break; 1601 case 'g': 1602 if ((options.login_grace_time = convtime(optarg)) == -1) { 1603 fprintf(stderr, "Invalid login grace time.\n"); 1604 exit(1); 1605 } 1606 break; 1607 case 'k': 1608 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1609 fprintf(stderr, "Invalid key regeneration interval.\n"); 1610 exit(1); 1611 } 1612 break; 1613 case 'h': 1614 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1615 fprintf(stderr, "too many host keys.\n"); 1616 exit(1); 1617 } 1618 options.host_key_files[options.num_host_key_files++] = 1619 derelativise_path(optarg); 1620 break; 1621 case 't': 1622 test_flag = 1; 1623 break; 1624 case 'T': 1625 test_flag = 2; 1626 break; 1627 case 'C': 1628 if (parse_server_match_testspec(connection_info, 1629 optarg) == -1) 1630 exit(1); 1631 break; 1632 case 'u': 1633 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1634 if (utmp_len > HOST_NAME_MAX+1) { 1635 fprintf(stderr, "Invalid utmp length.\n"); 1636 exit(1); 1637 } 1638 break; 1639 case 'o': 1640 line = xstrdup(optarg); 1641 if (process_server_config_line(&options, line, 1642 "command-line", 0, NULL, NULL) != 0) 1643 exit(1); 1644 free(line); 1645 break; 1646 case '?': 1647 default: 1648 usage(); 1649 break; 1650 } 1651 } 1652 if (rexeced_flag || inetd_flag) 1653 rexec_flag = 0; 1654 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1655 fatal("sshd re-exec requires execution with an absolute path"); 1656 if (rexeced_flag) 1657 closefrom(REEXEC_MIN_FREE_FD); 1658 else 1659 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1660 1661 #ifdef WITH_OPENSSL 1662 OpenSSL_add_all_algorithms(); 1663 #endif 1664 1665 /* If requested, redirect the logs to the specified logfile. */ 1666 if (logfile != NULL) 1667 log_redirect_stderr_to(logfile); 1668 /* 1669 * Force logging to stderr until we have loaded the private host 1670 * key (unless started from inetd) 1671 */ 1672 log_init(__progname, 1673 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1674 SYSLOG_LEVEL_INFO : options.log_level, 1675 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1676 SYSLOG_FACILITY_AUTH : options.log_facility, 1677 log_stderr || !inetd_flag); 1678 1679 /* 1680 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1681 * root's environment 1682 */ 1683 if (getenv("KRB5CCNAME") != NULL) 1684 (void) unsetenv("KRB5CCNAME"); 1685 1686 #ifdef _UNICOS 1687 /* Cray can define user privs drop all privs now! 1688 * Not needed on PRIV_SU systems! 1689 */ 1690 drop_cray_privs(); 1691 #endif 1692 1693 sensitive_data.server_key = NULL; 1694 sensitive_data.ssh1_host_key = NULL; 1695 sensitive_data.have_ssh1_key = 0; 1696 sensitive_data.have_ssh2_key = 0; 1697 1698 /* 1699 * If we're doing an extended config test, make sure we have all of 1700 * the parameters we need. If we're not doing an extended test, 1701 * do not silently ignore connection test params. 1702 */ 1703 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0) 1704 fatal("user, host and addr are all required when testing " 1705 "Match configs"); 1706 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0) 1707 fatal("Config test connection parameter (-C) provided without " 1708 "test mode (-T)"); 1709 1710 /* Fetch our configuration */ 1711 buffer_init(&cfg); 1712 if (rexeced_flag) 1713 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1714 else if (strcasecmp(config_file_name, "none") != 0) 1715 load_server_config(config_file_name, &cfg); 1716 1717 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1718 &cfg, NULL); 1719 1720 seed_rng(); 1721 1722 /* Fill in default values for those options not explicitly set. */ 1723 fill_default_server_options(&options); 1724 1725 /* challenge-response is implemented via keyboard interactive */ 1726 if (options.challenge_response_authentication) 1727 options.kbd_interactive_authentication = 1; 1728 1729 /* Check that options are sensible */ 1730 if (options.authorized_keys_command_user == NULL && 1731 (options.authorized_keys_command != NULL && 1732 strcasecmp(options.authorized_keys_command, "none") != 0)) 1733 fatal("AuthorizedKeysCommand set without " 1734 "AuthorizedKeysCommandUser"); 1735 if (options.authorized_principals_command_user == NULL && 1736 (options.authorized_principals_command != NULL && 1737 strcasecmp(options.authorized_principals_command, "none") != 0)) 1738 fatal("AuthorizedPrincipalsCommand set without " 1739 "AuthorizedPrincipalsCommandUser"); 1740 1741 /* 1742 * Check whether there is any path through configured auth methods. 1743 * Unfortunately it is not possible to verify this generally before 1744 * daemonisation in the presence of Match block, but this catches 1745 * and warns for trivial misconfigurations that could break login. 1746 */ 1747 if (options.num_auth_methods != 0) { 1748 if ((options.protocol & SSH_PROTO_1)) 1749 fatal("AuthenticationMethods is not supported with " 1750 "SSH protocol 1"); 1751 for (n = 0; n < options.num_auth_methods; n++) { 1752 if (auth2_methods_valid(options.auth_methods[n], 1753 1) == 0) 1754 break; 1755 } 1756 if (n >= options.num_auth_methods) 1757 fatal("AuthenticationMethods cannot be satisfied by " 1758 "enabled authentication methods"); 1759 } 1760 1761 /* set default channel AF */ 1762 channel_set_af(options.address_family); 1763 1764 /* Check that there are no remaining arguments. */ 1765 if (optind < ac) { 1766 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1767 exit(1); 1768 } 1769 1770 debug("sshd version %s, %s", SSH_VERSION, 1771 #ifdef WITH_OPENSSL 1772 SSLeay_version(SSLEAY_VERSION) 1773 #else 1774 "without OpenSSL" 1775 #endif 1776 ); 1777 1778 /* Store privilege separation user for later use if required. */ 1779 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1780 if (use_privsep || options.kerberos_authentication) 1781 fatal("Privilege separation user %s does not exist", 1782 SSH_PRIVSEP_USER); 1783 } else { 1784 explicit_bzero(privsep_pw->pw_passwd, 1785 strlen(privsep_pw->pw_passwd)); 1786 privsep_pw = pwcopy(privsep_pw); 1787 free(privsep_pw->pw_passwd); 1788 privsep_pw->pw_passwd = xstrdup("*"); 1789 } 1790 endpwent(); 1791 1792 /* load host keys */ 1793 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1794 sizeof(Key *)); 1795 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1796 sizeof(Key *)); 1797 1798 if (options.host_key_agent) { 1799 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1800 setenv(SSH_AUTHSOCKET_ENV_NAME, 1801 options.host_key_agent, 1); 1802 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1803 have_agent = 1; 1804 else 1805 error("Could not connect to agent \"%s\": %s", 1806 options.host_key_agent, ssh_err(r)); 1807 } 1808 1809 for (i = 0; i < options.num_host_key_files; i++) { 1810 if (options.host_key_files[i] == NULL) 1811 continue; 1812 key = key_load_private(options.host_key_files[i], "", NULL); 1813 pubkey = key_load_public(options.host_key_files[i], NULL); 1814 if (pubkey == NULL && key != NULL) 1815 pubkey = key_demote(key); 1816 sensitive_data.host_keys[i] = key; 1817 sensitive_data.host_pubkeys[i] = pubkey; 1818 1819 if (key == NULL && pubkey != NULL && pubkey->type != KEY_RSA1 && 1820 have_agent) { 1821 debug("will rely on agent for hostkey %s", 1822 options.host_key_files[i]); 1823 keytype = pubkey->type; 1824 } else if (key != NULL) { 1825 keytype = key->type; 1826 } else { 1827 error("Could not load host key: %s", 1828 options.host_key_files[i]); 1829 sensitive_data.host_keys[i] = NULL; 1830 sensitive_data.host_pubkeys[i] = NULL; 1831 continue; 1832 } 1833 1834 switch (keytype) { 1835 case KEY_RSA1: 1836 sensitive_data.ssh1_host_key = key; 1837 sensitive_data.have_ssh1_key = 1; 1838 break; 1839 case KEY_RSA: 1840 case KEY_DSA: 1841 case KEY_ECDSA: 1842 case KEY_ED25519: 1843 if (have_agent || key != NULL) 1844 sensitive_data.have_ssh2_key = 1; 1845 break; 1846 } 1847 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1848 SSH_FP_DEFAULT)) == NULL) 1849 fatal("sshkey_fingerprint failed"); 1850 debug("%s host key #%d: %s %s", 1851 key ? "private" : "agent", i, keytype == KEY_RSA1 ? 1852 sshkey_type(pubkey) : sshkey_ssh_name(pubkey), fp); 1853 free(fp); 1854 } 1855 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1856 logit("Disabling protocol version 1. Could not load host key"); 1857 options.protocol &= ~SSH_PROTO_1; 1858 } 1859 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1860 logit("Disabling protocol version 2. Could not load host key"); 1861 options.protocol &= ~SSH_PROTO_2; 1862 } 1863 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1864 logit("sshd: no hostkeys available -- exiting."); 1865 exit(1); 1866 } 1867 1868 /* 1869 * Load certificates. They are stored in an array at identical 1870 * indices to the public keys that they relate to. 1871 */ 1872 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1873 sizeof(Key *)); 1874 for (i = 0; i < options.num_host_key_files; i++) 1875 sensitive_data.host_certificates[i] = NULL; 1876 1877 for (i = 0; i < options.num_host_cert_files; i++) { 1878 if (options.host_cert_files[i] == NULL) 1879 continue; 1880 key = key_load_public(options.host_cert_files[i], NULL); 1881 if (key == NULL) { 1882 error("Could not load host certificate: %s", 1883 options.host_cert_files[i]); 1884 continue; 1885 } 1886 if (!key_is_cert(key)) { 1887 error("Certificate file is not a certificate: %s", 1888 options.host_cert_files[i]); 1889 key_free(key); 1890 continue; 1891 } 1892 /* Find matching private key */ 1893 for (j = 0; j < options.num_host_key_files; j++) { 1894 if (key_equal_public(key, 1895 sensitive_data.host_keys[j])) { 1896 sensitive_data.host_certificates[j] = key; 1897 break; 1898 } 1899 } 1900 if (j >= options.num_host_key_files) { 1901 error("No matching private key for certificate: %s", 1902 options.host_cert_files[i]); 1903 key_free(key); 1904 continue; 1905 } 1906 sensitive_data.host_certificates[j] = key; 1907 debug("host certificate: #%d type %d %s", j, key->type, 1908 key_type(key)); 1909 } 1910 1911 #ifdef WITH_SSH1 1912 /* Check certain values for sanity. */ 1913 if (options.protocol & SSH_PROTO_1) { 1914 if (options.server_key_bits < SSH_RSA_MINIMUM_MODULUS_SIZE || 1915 options.server_key_bits > OPENSSL_RSA_MAX_MODULUS_BITS) { 1916 fprintf(stderr, "Bad server key size.\n"); 1917 exit(1); 1918 } 1919 /* 1920 * Check that server and host key lengths differ sufficiently. This 1921 * is necessary to make double encryption work with rsaref. Oh, I 1922 * hate software patents. I dont know if this can go? Niels 1923 */ 1924 if (options.server_key_bits > 1925 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1926 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1927 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1928 SSH_KEY_BITS_RESERVED) { 1929 options.server_key_bits = 1930 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1931 SSH_KEY_BITS_RESERVED; 1932 debug("Forcing server key to %d bits to make it differ from host key.", 1933 options.server_key_bits); 1934 } 1935 } 1936 #endif 1937 1938 if (use_privsep) { 1939 struct stat st; 1940 1941 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1942 (S_ISDIR(st.st_mode) == 0)) 1943 fatal("Missing privilege separation directory: %s", 1944 _PATH_PRIVSEP_CHROOT_DIR); 1945 1946 #ifdef HAVE_CYGWIN 1947 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1948 (st.st_uid != getuid () || 1949 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1950 #else 1951 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1952 #endif 1953 fatal("%s must be owned by root and not group or " 1954 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1955 } 1956 1957 if (test_flag > 1) { 1958 if (server_match_spec_complete(connection_info) == 1) 1959 parse_server_match_config(&options, connection_info); 1960 dump_config(&options); 1961 } 1962 1963 /* Configuration looks good, so exit if in test mode. */ 1964 if (test_flag) 1965 exit(0); 1966 1967 /* 1968 * Clear out any supplemental groups we may have inherited. This 1969 * prevents inadvertent creation of files with bad modes (in the 1970 * portable version at least, it's certainly possible for PAM 1971 * to create a file, and we can't control the code in every 1972 * module which might be used). 1973 */ 1974 if (setgroups(0, NULL) < 0) 1975 debug("setgroups() failed: %.200s", strerror(errno)); 1976 1977 if (rexec_flag) { 1978 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1979 for (i = 0; i < rexec_argc; i++) { 1980 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1981 rexec_argv[i] = saved_argv[i]; 1982 } 1983 rexec_argv[rexec_argc] = "-R"; 1984 rexec_argv[rexec_argc + 1] = NULL; 1985 } 1986 1987 /* Ensure that umask disallows at least group and world write */ 1988 new_umask = umask(0077) | 0022; 1989 (void) umask(new_umask); 1990 1991 /* Initialize the log (it is reinitialized below in case we forked). */ 1992 if (debug_flag && (!inetd_flag || rexeced_flag)) 1993 log_stderr = 1; 1994 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1995 1996 /* 1997 * If not in debugging mode, and not started from inetd, disconnect 1998 * from the controlling terminal, and fork. The original process 1999 * exits. 2000 */ 2001 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 2002 #ifdef TIOCNOTTY 2003 int fd; 2004 #endif /* TIOCNOTTY */ 2005 if (daemon(0, 0) < 0) 2006 fatal("daemon() failed: %.200s", strerror(errno)); 2007 2008 /* Disconnect from the controlling tty. */ 2009 #ifdef TIOCNOTTY 2010 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 2011 if (fd >= 0) { 2012 (void) ioctl(fd, TIOCNOTTY, NULL); 2013 close(fd); 2014 } 2015 #endif /* TIOCNOTTY */ 2016 } 2017 /* Reinitialize the log (because of the fork above). */ 2018 log_init(__progname, options.log_level, options.log_facility, log_stderr); 2019 2020 /* Avoid killing the process in high-pressure swapping environments. */ 2021 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 2022 debug("madvise(): %.200s", strerror(errno)); 2023 2024 /* Chdir to the root directory so that the current disk can be 2025 unmounted if desired. */ 2026 if (chdir("/") == -1) 2027 error("chdir(\"/\"): %s", strerror(errno)); 2028 2029 /* ignore SIGPIPE */ 2030 signal(SIGPIPE, SIG_IGN); 2031 2032 /* Get a connection, either from inetd or a listening TCP socket */ 2033 if (inetd_flag) { 2034 server_accept_inetd(&sock_in, &sock_out); 2035 } else { 2036 platform_pre_listen(); 2037 server_listen(); 2038 2039 if (options.protocol & SSH_PROTO_1) 2040 generate_ephemeral_server_key(); 2041 2042 signal(SIGHUP, sighup_handler); 2043 signal(SIGCHLD, main_sigchld_handler); 2044 signal(SIGTERM, sigterm_handler); 2045 signal(SIGQUIT, sigterm_handler); 2046 2047 /* 2048 * Write out the pid file after the sigterm handler 2049 * is setup and the listen sockets are bound 2050 */ 2051 if (options.pid_file != NULL && !debug_flag) { 2052 FILE *f = fopen(options.pid_file, "w"); 2053 2054 if (f == NULL) { 2055 error("Couldn't create pid file \"%s\": %s", 2056 options.pid_file, strerror(errno)); 2057 } else { 2058 fprintf(f, "%ld\n", (long) getpid()); 2059 fclose(f); 2060 } 2061 } 2062 2063 /* Accept a connection and return in a forked child */ 2064 server_accept_loop(&sock_in, &sock_out, 2065 &newsock, config_s); 2066 } 2067 2068 /* This is the child processing a new connection. */ 2069 setproctitle("%s", "[accepted]"); 2070 2071 /* 2072 * Create a new session and process group since the 4.4BSD 2073 * setlogin() affects the entire process group. We don't 2074 * want the child to be able to affect the parent. 2075 */ 2076 #if !defined(SSHD_ACQUIRES_CTTY) 2077 /* 2078 * If setsid is called, on some platforms sshd will later acquire a 2079 * controlling terminal which will result in "could not set 2080 * controlling tty" errors. 2081 */ 2082 if (!debug_flag && !inetd_flag && setsid() < 0) 2083 error("setsid: %.100s", strerror(errno)); 2084 #endif 2085 2086 if (rexec_flag) { 2087 int fd; 2088 2089 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 2090 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2091 dup2(newsock, STDIN_FILENO); 2092 dup2(STDIN_FILENO, STDOUT_FILENO); 2093 if (startup_pipe == -1) 2094 close(REEXEC_STARTUP_PIPE_FD); 2095 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 2096 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 2097 close(startup_pipe); 2098 startup_pipe = REEXEC_STARTUP_PIPE_FD; 2099 } 2100 2101 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 2102 close(config_s[1]); 2103 2104 execv(rexec_argv[0], rexec_argv); 2105 2106 /* Reexec has failed, fall back and continue */ 2107 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 2108 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 2109 log_init(__progname, options.log_level, 2110 options.log_facility, log_stderr); 2111 2112 /* Clean up fds */ 2113 close(REEXEC_CONFIG_PASS_FD); 2114 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2115 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 2116 dup2(fd, STDIN_FILENO); 2117 dup2(fd, STDOUT_FILENO); 2118 if (fd > STDERR_FILENO) 2119 close(fd); 2120 } 2121 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2122 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2123 } 2124 2125 /* Executed child processes don't need these. */ 2126 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2127 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2128 2129 /* 2130 * Disable the key regeneration alarm. We will not regenerate the 2131 * key since we are no longer in a position to give it to anyone. We 2132 * will not restart on SIGHUP since it no longer makes sense. 2133 */ 2134 alarm(0); 2135 signal(SIGALRM, SIG_DFL); 2136 signal(SIGHUP, SIG_DFL); 2137 signal(SIGTERM, SIG_DFL); 2138 signal(SIGQUIT, SIG_DFL); 2139 signal(SIGCHLD, SIG_DFL); 2140 signal(SIGINT, SIG_DFL); 2141 2142 #ifdef __FreeBSD__ 2143 /* 2144 * Initialize the resolver. This may not happen automatically 2145 * before privsep chroot(). 2146 */ 2147 if ((_res.options & RES_INIT) == 0) { 2148 debug("res_init()"); 2149 res_init(); 2150 } 2151 #ifdef GSSAPI 2152 /* 2153 * Force GSS-API to parse its configuration and load any 2154 * mechanism plugins. 2155 */ 2156 { 2157 gss_OID_set mechs; 2158 OM_uint32 minor_status; 2159 gss_indicate_mechs(&minor_status, &mechs); 2160 gss_release_oid_set(&minor_status, &mechs); 2161 } 2162 #endif 2163 #endif 2164 2165 /* 2166 * Register our connection. This turns encryption off because we do 2167 * not have a key. 2168 */ 2169 packet_set_connection(sock_in, sock_out); 2170 packet_set_server(); 2171 2172 /* Set SO_KEEPALIVE if requested. */ 2173 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 2174 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 2175 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2176 2177 if ((remote_port = get_remote_port()) < 0) { 2178 debug("get_remote_port failed"); 2179 cleanup_exit(255); 2180 } 2181 2182 /* 2183 * We use get_canonical_hostname with usedns = 0 instead of 2184 * get_remote_ipaddr here so IP options will be checked. 2185 */ 2186 (void) get_canonical_hostname(0); 2187 /* 2188 * The rest of the code depends on the fact that 2189 * get_remote_ipaddr() caches the remote ip, even if 2190 * the socket goes away. 2191 */ 2192 remote_ip = get_remote_ipaddr(); 2193 2194 #ifdef SSH_AUDIT_EVENTS 2195 audit_connection_from(remote_ip, remote_port); 2196 #endif 2197 #ifdef LIBWRAP 2198 allow_severity = options.log_facility|LOG_INFO; 2199 deny_severity = options.log_facility|LOG_WARNING; 2200 /* Check whether logins are denied from this host. */ 2201 if (packet_connection_is_on_socket()) { 2202 struct request_info req; 2203 2204 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 2205 fromhost(&req); 2206 2207 if (!hosts_access(&req)) { 2208 debug("Connection refused by tcp wrapper"); 2209 refuse(&req); 2210 /* NOTREACHED */ 2211 fatal("libwrap refuse returns"); 2212 } 2213 } 2214 #endif /* LIBWRAP */ 2215 2216 /* Log the connection. */ 2217 laddr = get_local_ipaddr(sock_in); 2218 verbose("Connection from %s port %d on %s port %d", 2219 remote_ip, remote_port, laddr, get_local_port()); 2220 free(laddr); 2221 2222 /* 2223 * We don't want to listen forever unless the other side 2224 * successfully authenticates itself. So we set up an alarm which is 2225 * cleared after successful authentication. A limit of zero 2226 * indicates no limit. Note that we don't set the alarm in debugging 2227 * mode; it is just annoying to have the server exit just when you 2228 * are about to discover the bug. 2229 */ 2230 signal(SIGALRM, grace_alarm_handler); 2231 if (!debug_flag) 2232 alarm(options.login_grace_time); 2233 2234 sshd_exchange_identification(sock_in, sock_out); 2235 2236 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 2237 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 2238 generate_ephemeral_server_key(); 2239 2240 packet_set_nonblocking(); 2241 2242 /* allocate authentication context */ 2243 authctxt = xcalloc(1, sizeof(*authctxt)); 2244 2245 authctxt->loginmsg = &loginmsg; 2246 2247 /* XXX global for cleanup, access from other modules */ 2248 the_authctxt = authctxt; 2249 2250 /* prepare buffer to collect messages to display to user after login */ 2251 buffer_init(&loginmsg); 2252 auth_debug_reset(); 2253 2254 if (use_privsep) { 2255 if (privsep_preauth(authctxt) == 1) 2256 goto authenticated; 2257 } else if (compat20 && have_agent) { 2258 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2259 error("Unable to get agent socket: %s", ssh_err(r)); 2260 have_agent = 0; 2261 } 2262 } 2263 2264 /* perform the key exchange */ 2265 /* authenticate user and start session */ 2266 if (compat20) { 2267 do_ssh2_kex(); 2268 do_authentication2(authctxt); 2269 } else { 2270 #ifdef WITH_SSH1 2271 do_ssh1_kex(); 2272 do_authentication(authctxt); 2273 #else 2274 fatal("ssh1 not supported"); 2275 #endif 2276 } 2277 /* 2278 * If we use privilege separation, the unprivileged child transfers 2279 * the current keystate and exits 2280 */ 2281 if (use_privsep) { 2282 mm_send_keystate(pmonitor); 2283 exit(0); 2284 } 2285 2286 authenticated: 2287 /* 2288 * Cancel the alarm we set to limit the time taken for 2289 * authentication. 2290 */ 2291 alarm(0); 2292 signal(SIGALRM, SIG_DFL); 2293 authctxt->authenticated = 1; 2294 if (startup_pipe != -1) { 2295 close(startup_pipe); 2296 startup_pipe = -1; 2297 } 2298 2299 #ifdef SSH_AUDIT_EVENTS 2300 audit_event(SSH_AUTH_SUCCESS); 2301 #endif 2302 2303 #ifdef GSSAPI 2304 if (options.gss_authentication) { 2305 temporarily_use_uid(authctxt->pw); 2306 ssh_gssapi_storecreds(); 2307 restore_uid(); 2308 } 2309 #endif 2310 #ifdef USE_PAM 2311 if (options.use_pam) { 2312 do_pam_setcred(1); 2313 do_pam_session(); 2314 } 2315 #endif 2316 2317 /* 2318 * In privilege separation, we fork another child and prepare 2319 * file descriptor passing. 2320 */ 2321 if (use_privsep) { 2322 privsep_postauth(authctxt); 2323 /* the monitor process [priv] will not return */ 2324 if (!compat20) 2325 destroy_sensitive_data(); 2326 } 2327 2328 packet_set_timeout(options.client_alive_interval, 2329 options.client_alive_count_max); 2330 2331 /* Try to send all our hostkeys to the client */ 2332 if (compat20) 2333 notify_hostkeys(active_state); 2334 2335 /* Start session. */ 2336 do_authenticated(authctxt); 2337 2338 /* The connection has been terminated. */ 2339 packet_get_bytes(&ibytes, &obytes); 2340 verbose("Transferred: sent %llu, received %llu bytes", 2341 (unsigned long long)obytes, (unsigned long long)ibytes); 2342 2343 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2344 2345 #ifdef USE_PAM 2346 if (options.use_pam) 2347 finish_pam(); 2348 #endif /* USE_PAM */ 2349 2350 #ifdef SSH_AUDIT_EVENTS 2351 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2352 #endif 2353 2354 packet_close(); 2355 2356 if (use_privsep) 2357 mm_terminate(); 2358 2359 exit(0); 2360 } 2361 2362 #ifdef WITH_SSH1 2363 /* 2364 * Decrypt session_key_int using our private server key and private host key 2365 * (key with larger modulus first). 2366 */ 2367 int 2368 ssh1_session_key(BIGNUM *session_key_int) 2369 { 2370 int rsafail = 0; 2371 2372 if (BN_cmp(sensitive_data.server_key->rsa->n, 2373 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2374 /* Server key has bigger modulus. */ 2375 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2376 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2377 SSH_KEY_BITS_RESERVED) { 2378 fatal("do_connection: %s: " 2379 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2380 get_remote_ipaddr(), 2381 BN_num_bits(sensitive_data.server_key->rsa->n), 2382 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2383 SSH_KEY_BITS_RESERVED); 2384 } 2385 if (rsa_private_decrypt(session_key_int, session_key_int, 2386 sensitive_data.server_key->rsa) != 0) 2387 rsafail++; 2388 if (rsa_private_decrypt(session_key_int, session_key_int, 2389 sensitive_data.ssh1_host_key->rsa) != 0) 2390 rsafail++; 2391 } else { 2392 /* Host key has bigger modulus (or they are equal). */ 2393 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2394 BN_num_bits(sensitive_data.server_key->rsa->n) + 2395 SSH_KEY_BITS_RESERVED) { 2396 fatal("do_connection: %s: " 2397 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2398 get_remote_ipaddr(), 2399 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2400 BN_num_bits(sensitive_data.server_key->rsa->n), 2401 SSH_KEY_BITS_RESERVED); 2402 } 2403 if (rsa_private_decrypt(session_key_int, session_key_int, 2404 sensitive_data.ssh1_host_key->rsa) != 0) 2405 rsafail++; 2406 if (rsa_private_decrypt(session_key_int, session_key_int, 2407 sensitive_data.server_key->rsa) != 0) 2408 rsafail++; 2409 } 2410 return (rsafail); 2411 } 2412 2413 /* 2414 * SSH1 key exchange 2415 */ 2416 static void 2417 do_ssh1_kex(void) 2418 { 2419 int i, len; 2420 int rsafail = 0; 2421 BIGNUM *session_key_int, *fake_key_int, *real_key_int; 2422 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2423 u_char fake_key_bytes[4096 / 8]; 2424 size_t fake_key_len; 2425 u_char cookie[8]; 2426 u_int cipher_type, auth_mask, protocol_flags; 2427 2428 /* 2429 * Generate check bytes that the client must send back in the user 2430 * packet in order for it to be accepted; this is used to defy ip 2431 * spoofing attacks. Note that this only works against somebody 2432 * doing IP spoofing from a remote machine; any machine on the local 2433 * network can still see outgoing packets and catch the random 2434 * cookie. This only affects rhosts authentication, and this is one 2435 * of the reasons why it is inherently insecure. 2436 */ 2437 arc4random_buf(cookie, sizeof(cookie)); 2438 2439 /* 2440 * Send our public key. We include in the packet 64 bits of random 2441 * data that must be matched in the reply in order to prevent IP 2442 * spoofing. 2443 */ 2444 packet_start(SSH_SMSG_PUBLIC_KEY); 2445 for (i = 0; i < 8; i++) 2446 packet_put_char(cookie[i]); 2447 2448 /* Store our public server RSA key. */ 2449 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2450 packet_put_bignum(sensitive_data.server_key->rsa->e); 2451 packet_put_bignum(sensitive_data.server_key->rsa->n); 2452 2453 /* Store our public host RSA key. */ 2454 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2455 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2456 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2457 2458 /* Put protocol flags. */ 2459 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2460 2461 /* Declare which ciphers we support. */ 2462 packet_put_int(cipher_mask_ssh1(0)); 2463 2464 /* Declare supported authentication types. */ 2465 auth_mask = 0; 2466 if (options.rhosts_rsa_authentication) 2467 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2468 if (options.rsa_authentication) 2469 auth_mask |= 1 << SSH_AUTH_RSA; 2470 if (options.challenge_response_authentication == 1) 2471 auth_mask |= 1 << SSH_AUTH_TIS; 2472 if (options.password_authentication) 2473 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2474 packet_put_int(auth_mask); 2475 2476 /* Send the packet and wait for it to be sent. */ 2477 packet_send(); 2478 packet_write_wait(); 2479 2480 debug("Sent %d bit server key and %d bit host key.", 2481 BN_num_bits(sensitive_data.server_key->rsa->n), 2482 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2483 2484 /* Read clients reply (cipher type and session key). */ 2485 packet_read_expect(SSH_CMSG_SESSION_KEY); 2486 2487 /* Get cipher type and check whether we accept this. */ 2488 cipher_type = packet_get_char(); 2489 2490 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2491 packet_disconnect("Warning: client selects unsupported cipher."); 2492 2493 /* Get check bytes from the packet. These must match those we 2494 sent earlier with the public key packet. */ 2495 for (i = 0; i < 8; i++) 2496 if (cookie[i] != packet_get_char()) 2497 packet_disconnect("IP Spoofing check bytes do not match."); 2498 2499 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2500 2501 /* Get the encrypted integer. */ 2502 if ((real_key_int = BN_new()) == NULL) 2503 fatal("do_ssh1_kex: BN_new failed"); 2504 packet_get_bignum(real_key_int); 2505 2506 protocol_flags = packet_get_int(); 2507 packet_set_protocol_flags(protocol_flags); 2508 packet_check_eom(); 2509 2510 /* Setup a fake key in case RSA decryption fails */ 2511 if ((fake_key_int = BN_new()) == NULL) 2512 fatal("do_ssh1_kex: BN_new failed"); 2513 fake_key_len = BN_num_bytes(real_key_int); 2514 if (fake_key_len > sizeof(fake_key_bytes)) 2515 fake_key_len = sizeof(fake_key_bytes); 2516 arc4random_buf(fake_key_bytes, fake_key_len); 2517 if (BN_bin2bn(fake_key_bytes, fake_key_len, fake_key_int) == NULL) 2518 fatal("do_ssh1_kex: BN_bin2bn failed"); 2519 2520 /* Decrypt real_key_int using host/server keys */ 2521 rsafail = PRIVSEP(ssh1_session_key(real_key_int)); 2522 /* If decryption failed, use the fake key. Else, the real key. */ 2523 if (rsafail) 2524 session_key_int = fake_key_int; 2525 else 2526 session_key_int = real_key_int; 2527 2528 /* 2529 * Extract session key from the decrypted integer. The key is in the 2530 * least significant 256 bits of the integer; the first byte of the 2531 * key is in the highest bits. 2532 */ 2533 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2534 len = BN_num_bytes(session_key_int); 2535 if (len < 0 || (u_int)len > sizeof(session_key)) { 2536 error("do_ssh1_kex: bad session key len from %s: " 2537 "session_key_int %d > sizeof(session_key) %lu", 2538 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2539 rsafail++; 2540 } else { 2541 explicit_bzero(session_key, sizeof(session_key)); 2542 BN_bn2bin(session_key_int, 2543 session_key + sizeof(session_key) - len); 2544 2545 derive_ssh1_session_id( 2546 sensitive_data.ssh1_host_key->rsa->n, 2547 sensitive_data.server_key->rsa->n, 2548 cookie, session_id); 2549 /* 2550 * Xor the first 16 bytes of the session key with the 2551 * session id. 2552 */ 2553 for (i = 0; i < 16; i++) 2554 session_key[i] ^= session_id[i]; 2555 } 2556 2557 /* Destroy the private and public keys. No longer. */ 2558 destroy_sensitive_data(); 2559 2560 if (use_privsep) 2561 mm_ssh1_session_id(session_id); 2562 2563 /* Destroy the decrypted integer. It is no longer needed. */ 2564 BN_clear_free(real_key_int); 2565 BN_clear_free(fake_key_int); 2566 2567 /* Set the session key. From this on all communications will be encrypted. */ 2568 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2569 2570 /* Destroy our copy of the session key. It is no longer needed. */ 2571 explicit_bzero(session_key, sizeof(session_key)); 2572 2573 debug("Received session key; encryption turned on."); 2574 2575 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2576 packet_start(SSH_SMSG_SUCCESS); 2577 packet_send(); 2578 packet_write_wait(); 2579 } 2580 #endif 2581 2582 int 2583 sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, size_t *slen, 2584 const u_char *data, size_t dlen, const char *alg, u_int flag) 2585 { 2586 int r; 2587 u_int xxx_slen, xxx_dlen = dlen; 2588 2589 if (privkey) { 2590 if (PRIVSEP(key_sign(privkey, signature, &xxx_slen, data, xxx_dlen, 2591 alg) < 0)) 2592 fatal("%s: key_sign failed", __func__); 2593 if (slen) 2594 *slen = xxx_slen; 2595 } else if (use_privsep) { 2596 if (mm_key_sign(pubkey, signature, &xxx_slen, data, xxx_dlen, 2597 alg) < 0) 2598 fatal("%s: pubkey_sign failed", __func__); 2599 if (slen) 2600 *slen = xxx_slen; 2601 } else { 2602 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slen, 2603 data, dlen, alg, datafellows)) != 0) 2604 fatal("%s: ssh_agent_sign failed: %s", 2605 __func__, ssh_err(r)); 2606 } 2607 return 0; 2608 } 2609 2610 /* SSH2 key exchange */ 2611 static void 2612 do_ssh2_kex(void) 2613 { 2614 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2615 struct kex *kex; 2616 int r; 2617 2618 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2619 options.kex_algorithms); 2620 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2621 options.ciphers); 2622 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2623 options.ciphers); 2624 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2625 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2626 2627 if (options.compression == COMP_NONE) { 2628 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2629 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2630 } else if (options.compression == COMP_DELAYED) { 2631 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2632 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2633 } 2634 2635 if (options.rekey_limit || options.rekey_interval) 2636 packet_set_rekey_limits(options.rekey_limit, 2637 (time_t)options.rekey_interval); 2638 2639 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2640 list_hostkey_types()); 2641 2642 /* start key exchange */ 2643 if ((r = kex_setup(active_state, myproposal)) != 0) 2644 fatal("kex_setup: %s", ssh_err(r)); 2645 kex = active_state->kex; 2646 #ifdef WITH_OPENSSL 2647 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2648 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2649 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2650 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2651 # ifdef OPENSSL_HAS_ECC 2652 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2653 # endif 2654 #endif 2655 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2656 kex->server = 1; 2657 kex->client_version_string=client_version_string; 2658 kex->server_version_string=server_version_string; 2659 kex->load_host_public_key=&get_hostkey_public_by_type; 2660 kex->load_host_private_key=&get_hostkey_private_by_type; 2661 kex->host_key_index=&get_hostkey_index; 2662 kex->sign = sshd_hostkey_sign; 2663 2664 dispatch_run(DISPATCH_BLOCK, &kex->done, active_state); 2665 2666 session_id2 = kex->session_id; 2667 session_id2_len = kex->session_id_len; 2668 2669 #ifdef DEBUG_KEXDH 2670 /* send 1st encrypted/maced/compressed message */ 2671 packet_start(SSH2_MSG_IGNORE); 2672 packet_put_cstring("markus"); 2673 packet_send(); 2674 packet_write_wait(); 2675 #endif 2676 debug("KEX done"); 2677 } 2678 2679 /* server specific fatal cleanup */ 2680 void 2681 cleanup_exit(int i) 2682 { 2683 if (the_authctxt) { 2684 do_cleanup(the_authctxt); 2685 if (use_privsep && privsep_is_preauth && 2686 pmonitor != NULL && pmonitor->m_pid > 1) { 2687 debug("Killing privsep child %d", pmonitor->m_pid); 2688 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2689 errno != ESRCH) 2690 error("%s: kill(%d): %s", __func__, 2691 pmonitor->m_pid, strerror(errno)); 2692 } 2693 } 2694 #ifdef SSH_AUDIT_EVENTS 2695 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2696 if (!use_privsep || mm_is_monitor()) 2697 audit_event(SSH_CONNECTION_ABANDON); 2698 #endif 2699 _exit(i); 2700 } 2701