1 /* $OpenBSD: sshd.c,v 1.458 2015/08/20 22:32:42 deraadt 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 "roaming.h" 136 #include "ssh-sandbox.h" 137 #include "version.h" 138 #include "ssherr.h" 139 140 #ifdef LIBWRAP 141 #include <tcpd.h> 142 #include <syslog.h> 143 int allow_severity; 144 int 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) 156 157 extern char *__progname; 158 159 /* Server configuration options. */ 160 ServerOptions options; 161 162 /* Name of the server configuration file. */ 163 char *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 */ 171 int debug_flag = 0; 172 173 /* Flag indicating that the daemon should only test the configuration and keys. */ 174 int test_flag = 0; 175 176 /* Flag indicating that the daemon is being started from inetd. */ 177 int inetd_flag = 0; 178 179 /* Flag indicating that sshd should not detach and become a daemon. */ 180 int no_daemon_flag = 0; 181 182 /* debug goes to stderr unless inetd_flag is set */ 183 int log_stderr = 0; 184 185 /* Saved arguments to main(). */ 186 char **saved_argv; 187 int saved_argc; 188 189 /* re-exec */ 190 int rexeced_flag = 0; 191 int rexec_flag = 1; 192 int rexec_argc = 0; 193 char **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 16 200 int listen_socks[MAX_LISTEN_SOCKS]; 201 int 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 */ 207 char *client_version_string = NULL; 208 char *server_version_string = NULL; 209 210 /* Daemon's agent connection */ 211 int auth_sock = -1; 212 int 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 */ 222 struct { 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 */ 237 static volatile sig_atomic_t key_do_regen = 0; 238 239 /* This is set to true when a signal is received. */ 240 static volatile sig_atomic_t received_sighup = 0; 241 static volatile sig_atomic_t received_sigterm = 0; 242 243 /* session identifier, used by RSA-auth */ 244 u_char session_id[16]; 245 246 /* same for ssh2 */ 247 u_char *session_id2 = NULL; 248 u_int session_id2_len = 0; 249 250 /* record remote hostname or ip */ 251 u_int utmp_len = HOST_NAME_MAX+1; 252 253 /* options.max_startup sized array of fd ints */ 254 int *startup_pipes = NULL; 255 int startup_pipe; /* in child */ 256 257 /* variables used for privilege separation */ 258 int use_privsep = -1; 259 struct monitor *pmonitor = NULL; 260 int privsep_is_preauth = 1; 261 262 /* global authentication context */ 263 Authctxt *the_authctxt = NULL; 264 265 /* sshd_config buffer */ 266 Buffer cfg; 267 268 /* message to be displayed after login */ 269 Buffer loginmsg; 270 271 /* Unprivileged user */ 272 struct passwd *privsep_pw = NULL; 273 274 /* Prototypes for various functions defined later in this file. */ 275 void destroy_sensitive_data(void); 276 void demote_sensitive_data(void); 277 278 #ifdef WITH_SSH1 279 static void do_ssh1_kex(void); 280 #endif 281 static void do_ssh2_kex(void); 282 283 /* 284 * Close all listening sockets 285 */ 286 static void 287 close_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 } 295 296 static void 297 close_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*/ 314 static void 315 sighup_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 */ 328 static void 329 sighup_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*/ 347 static void 348 sigterm_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*/ 358 static void 359 main_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*/ 377 static void 378 grace_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 /* Log error and exit. */ 393 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 394 } 395 396 /* 397 * Signal handler for the key regeneration alarm. Note that this 398 * alarm only occurs in the daemon waiting for connections, and it does not 399 * do anything with the private key or random state before forking. 400 * Thus there should be no concurrency control/asynchronous execution 401 * problems. 402 */ 403 static void 404 generate_ephemeral_server_key(void) 405 { 406 verbose("Generating %s%d bit RSA key.", 407 sensitive_data.server_key ? "new " : "", options.server_key_bits); 408 if (sensitive_data.server_key != NULL) 409 key_free(sensitive_data.server_key); 410 sensitive_data.server_key = key_generate(KEY_RSA1, 411 options.server_key_bits); 412 verbose("RSA key generation complete."); 413 414 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 415 } 416 417 /*ARGSUSED*/ 418 static void 419 key_regeneration_alarm(int sig) 420 { 421 int save_errno = errno; 422 423 signal(SIGALRM, SIG_DFL); 424 errno = save_errno; 425 key_do_regen = 1; 426 } 427 428 static void 429 sshd_exchange_identification(int sock_in, int sock_out) 430 { 431 u_int i; 432 int mismatch; 433 int remote_major, remote_minor; 434 int major, minor; 435 char *s, *newline = "\n"; 436 char buf[256]; /* Must not be larger than remote_version. */ 437 char remote_version[256]; /* Must be at least as big as buf. */ 438 439 if ((options.protocol & SSH_PROTO_1) && 440 (options.protocol & SSH_PROTO_2)) { 441 major = PROTOCOL_MAJOR_1; 442 minor = 99; 443 } else if (options.protocol & SSH_PROTO_2) { 444 major = PROTOCOL_MAJOR_2; 445 minor = PROTOCOL_MINOR_2; 446 newline = "\r\n"; 447 } else { 448 major = PROTOCOL_MAJOR_1; 449 minor = PROTOCOL_MINOR_1; 450 } 451 452 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s", 453 major, minor, SSH_VERSION, 454 *options.version_addendum == '\0' ? "" : " ", 455 options.version_addendum, newline); 456 457 /* Send our protocol version identification. */ 458 if (roaming_atomicio(vwrite, sock_out, server_version_string, 459 strlen(server_version_string)) 460 != strlen(server_version_string)) { 461 logit("Could not write ident string to %s", get_remote_ipaddr()); 462 cleanup_exit(255); 463 } 464 465 /* Read other sides version identification. */ 466 memset(buf, 0, sizeof(buf)); 467 for (i = 0; i < sizeof(buf) - 1; i++) { 468 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 469 logit("Did not receive identification string from %s", 470 get_remote_ipaddr()); 471 cleanup_exit(255); 472 } 473 if (buf[i] == '\r') { 474 buf[i] = 0; 475 /* Kludge for F-Secure Macintosh < 1.0.2 */ 476 if (i == 12 && 477 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 478 break; 479 continue; 480 } 481 if (buf[i] == '\n') { 482 buf[i] = 0; 483 break; 484 } 485 } 486 buf[sizeof(buf) - 1] = 0; 487 client_version_string = xstrdup(buf); 488 489 /* 490 * Check that the versions match. In future this might accept 491 * several versions and set appropriate flags to handle them. 492 */ 493 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 494 &remote_major, &remote_minor, remote_version) != 3) { 495 s = "Protocol mismatch.\n"; 496 (void) atomicio(vwrite, sock_out, s, strlen(s)); 497 logit("Bad protocol version identification '%.100s' " 498 "from %s port %d", client_version_string, 499 get_remote_ipaddr(), get_remote_port()); 500 close(sock_in); 501 close(sock_out); 502 cleanup_exit(255); 503 } 504 debug("Client protocol version %d.%d; client software version %.100s", 505 remote_major, remote_minor, remote_version); 506 507 active_state->compat = compat_datafellows(remote_version); 508 509 if ((datafellows & SSH_BUG_PROBE) != 0) { 510 logit("probed from %s with %s. Don't panic.", 511 get_remote_ipaddr(), client_version_string); 512 cleanup_exit(255); 513 } 514 if ((datafellows & SSH_BUG_SCANNER) != 0) { 515 logit("scanned from %s with %s. Don't panic.", 516 get_remote_ipaddr(), client_version_string); 517 cleanup_exit(255); 518 } 519 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) { 520 logit("Client version \"%.100s\" uses unsafe RSA signature " 521 "scheme; disabling use of RSA keys", remote_version); 522 } 523 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) { 524 fatal("Client version \"%.100s\" uses unsafe key agreement; " 525 "refusing connection", remote_version); 526 } 527 528 mismatch = 0; 529 switch (remote_major) { 530 case 1: 531 if (remote_minor == 99) { 532 if (options.protocol & SSH_PROTO_2) 533 enable_compat20(); 534 else 535 mismatch = 1; 536 break; 537 } 538 if (!(options.protocol & SSH_PROTO_1)) { 539 mismatch = 1; 540 break; 541 } 542 if (remote_minor < 3) { 543 packet_disconnect("Your ssh version is too old and " 544 "is no longer supported. Please install a newer version."); 545 } else if (remote_minor == 3) { 546 /* note that this disables agent-forwarding */ 547 enable_compat13(); 548 } 549 break; 550 case 2: 551 if (options.protocol & SSH_PROTO_2) { 552 enable_compat20(); 553 break; 554 } 555 /* FALLTHROUGH */ 556 default: 557 mismatch = 1; 558 break; 559 } 560 chop(server_version_string); 561 debug("Local version string %.200s", server_version_string); 562 563 if (mismatch) { 564 s = "Protocol major versions differ.\n"; 565 (void) atomicio(vwrite, sock_out, s, strlen(s)); 566 close(sock_in); 567 close(sock_out); 568 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 569 get_remote_ipaddr(), 570 server_version_string, client_version_string); 571 cleanup_exit(255); 572 } 573 } 574 575 /* Destroy the host and server keys. They will no longer be needed. */ 576 void 577 destroy_sensitive_data(void) 578 { 579 int i; 580 581 if (sensitive_data.server_key) { 582 key_free(sensitive_data.server_key); 583 sensitive_data.server_key = NULL; 584 } 585 for (i = 0; i < options.num_host_key_files; i++) { 586 if (sensitive_data.host_keys[i]) { 587 key_free(sensitive_data.host_keys[i]); 588 sensitive_data.host_keys[i] = NULL; 589 } 590 if (sensitive_data.host_certificates[i]) { 591 key_free(sensitive_data.host_certificates[i]); 592 sensitive_data.host_certificates[i] = NULL; 593 } 594 } 595 sensitive_data.ssh1_host_key = NULL; 596 explicit_bzero(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 597 } 598 599 /* Demote private to public keys for network child */ 600 void 601 demote_sensitive_data(void) 602 { 603 Key *tmp; 604 int i; 605 606 if (sensitive_data.server_key) { 607 tmp = key_demote(sensitive_data.server_key); 608 key_free(sensitive_data.server_key); 609 sensitive_data.server_key = tmp; 610 } 611 612 for (i = 0; i < options.num_host_key_files; i++) { 613 if (sensitive_data.host_keys[i]) { 614 tmp = key_demote(sensitive_data.host_keys[i]); 615 key_free(sensitive_data.host_keys[i]); 616 sensitive_data.host_keys[i] = tmp; 617 if (tmp->type == KEY_RSA1) 618 sensitive_data.ssh1_host_key = tmp; 619 } 620 /* Certs do not need demotion */ 621 } 622 623 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 624 } 625 626 static void 627 privsep_preauth_child(void) 628 { 629 u_int32_t rnd[256]; 630 gid_t gidset[1]; 631 632 /* Enable challenge-response authentication for privilege separation */ 633 privsep_challenge_enable(); 634 635 #ifdef GSSAPI 636 /* Cache supported mechanism OIDs for later use */ 637 if (options.gss_authentication) 638 ssh_gssapi_prepare_supported_oids(); 639 #endif 640 641 arc4random_stir(); 642 arc4random_buf(rnd, sizeof(rnd)); 643 #ifdef WITH_OPENSSL 644 RAND_seed(rnd, sizeof(rnd)); 645 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 646 fatal("%s: RAND_bytes failed", __func__); 647 #endif 648 explicit_bzero(rnd, sizeof(rnd)); 649 650 /* Demote the private keys to public keys. */ 651 demote_sensitive_data(); 652 653 /* Change our root directory */ 654 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 655 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 656 strerror(errno)); 657 if (chdir("/") == -1) 658 fatal("chdir(\"/\"): %s", strerror(errno)); 659 660 /* Drop our privileges */ 661 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 662 (u_int)privsep_pw->pw_gid); 663 #if 0 664 /* XXX not ready, too heavy after chroot */ 665 do_setusercontext(privsep_pw); 666 #else 667 gidset[0] = privsep_pw->pw_gid; 668 if (setgroups(1, gidset) < 0) 669 fatal("setgroups: %.100s", strerror(errno)); 670 permanently_set_uid(privsep_pw); 671 #endif 672 } 673 674 static int 675 privsep_preauth(Authctxt *authctxt) 676 { 677 int status, r; 678 pid_t pid; 679 struct ssh_sandbox *box = NULL; 680 681 /* Set up unprivileged child process to deal with network data */ 682 pmonitor = monitor_init(); 683 /* Store a pointer to the kex for later rekeying */ 684 pmonitor->m_pkex = &active_state->kex; 685 686 if (use_privsep == PRIVSEP_ON) 687 box = ssh_sandbox_init(pmonitor); 688 pid = fork(); 689 if (pid == -1) { 690 fatal("fork of unprivileged child failed"); 691 } else if (pid != 0) { 692 debug2("Network child is on pid %ld", (long)pid); 693 694 pmonitor->m_pid = pid; 695 if (have_agent) { 696 r = ssh_get_authentication_socket(&auth_sock); 697 if (r != 0) { 698 error("Could not get agent socket: %s", 699 ssh_err(r)); 700 have_agent = 0; 701 } 702 } 703 if (box != NULL) 704 ssh_sandbox_parent_preauth(box, pid); 705 monitor_child_preauth(authctxt, pmonitor); 706 707 /* Sync memory */ 708 monitor_sync(pmonitor); 709 710 /* Wait for the child's exit status */ 711 while (waitpid(pid, &status, 0) < 0) { 712 if (errno == EINTR) 713 continue; 714 pmonitor->m_pid = -1; 715 fatal("%s: waitpid: %s", __func__, strerror(errno)); 716 } 717 privsep_is_preauth = 0; 718 pmonitor->m_pid = -1; 719 if (WIFEXITED(status)) { 720 if (WEXITSTATUS(status) != 0) 721 fatal("%s: preauth child exited with status %d", 722 __func__, WEXITSTATUS(status)); 723 } else if (WIFSIGNALED(status)) 724 fatal("%s: preauth child terminated by signal %d", 725 __func__, WTERMSIG(status)); 726 if (box != NULL) 727 ssh_sandbox_parent_finish(box); 728 return 1; 729 } else { 730 /* child */ 731 close(pmonitor->m_sendfd); 732 close(pmonitor->m_log_recvfd); 733 734 /* Arrange for logging to be sent to the monitor */ 735 set_log_handler(mm_log_handler, pmonitor); 736 737 /* Demote the child */ 738 if (getuid() == 0 || geteuid() == 0) 739 privsep_preauth_child(); 740 setproctitle("%s", "[net]"); 741 if (box != NULL) 742 ssh_sandbox_child(box); 743 744 return 0; 745 } 746 } 747 748 static void 749 privsep_postauth(Authctxt *authctxt) 750 { 751 u_int32_t rnd[256]; 752 753 #ifdef DISABLE_FD_PASSING 754 if (1) { 755 #else 756 if (authctxt->pw->pw_uid == 0 || options.use_login) { 757 #endif 758 /* File descriptor passing is broken or root login */ 759 use_privsep = 0; 760 goto skip; 761 } 762 763 /* New socket pair */ 764 monitor_reinit(pmonitor); 765 766 pmonitor->m_pid = fork(); 767 if (pmonitor->m_pid == -1) 768 fatal("fork of unprivileged child failed"); 769 else if (pmonitor->m_pid != 0) { 770 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 771 buffer_clear(&loginmsg); 772 monitor_child_postauth(pmonitor); 773 774 /* NEVERREACHED */ 775 exit(0); 776 } 777 778 /* child */ 779 780 close(pmonitor->m_sendfd); 781 pmonitor->m_sendfd = -1; 782 783 /* Demote the private keys to public keys. */ 784 demote_sensitive_data(); 785 786 arc4random_stir(); 787 arc4random_buf(rnd, sizeof(rnd)); 788 #ifdef WITH_OPENSSL 789 RAND_seed(rnd, sizeof(rnd)); 790 if ((RAND_bytes((u_char *)rnd, 1)) != 1) 791 fatal("%s: RAND_bytes failed", __func__); 792 #endif 793 explicit_bzero(rnd, sizeof(rnd)); 794 795 /* Drop privileges */ 796 do_setusercontext(authctxt->pw); 797 798 skip: 799 /* It is safe now to apply the key state */ 800 monitor_apply_keystate(pmonitor); 801 802 /* 803 * Tell the packet layer that authentication was successful, since 804 * this information is not part of the key state. 805 */ 806 packet_set_authenticated(); 807 } 808 809 static char * 810 list_hostkey_types(void) 811 { 812 Buffer b; 813 const char *p; 814 char *ret; 815 int i; 816 Key *key; 817 818 buffer_init(&b); 819 for (i = 0; i < options.num_host_key_files; i++) { 820 key = sensitive_data.host_keys[i]; 821 if (key == NULL) 822 key = sensitive_data.host_pubkeys[i]; 823 if (key == NULL || key->type == KEY_RSA1) 824 continue; 825 /* Check that the key is accepted in HostkeyAlgorithms */ 826 if (match_pattern_list(sshkey_ssh_name(key), 827 options.hostkeyalgorithms, 0) != 1) { 828 debug3("%s: %s key not permitted by HostkeyAlgorithms", 829 __func__, sshkey_ssh_name(key)); 830 continue; 831 } 832 switch (key->type) { 833 case KEY_RSA: 834 case KEY_DSA: 835 case KEY_ECDSA: 836 case KEY_ED25519: 837 if (buffer_len(&b) > 0) 838 buffer_append(&b, ",", 1); 839 p = key_ssh_name(key); 840 buffer_append(&b, p, strlen(p)); 841 break; 842 } 843 /* If the private key has a cert peer, then list that too */ 844 key = sensitive_data.host_certificates[i]; 845 if (key == NULL) 846 continue; 847 switch (key->type) { 848 case KEY_RSA_CERT: 849 case KEY_DSA_CERT: 850 case KEY_ECDSA_CERT: 851 case KEY_ED25519_CERT: 852 if (buffer_len(&b) > 0) 853 buffer_append(&b, ",", 1); 854 p = key_ssh_name(key); 855 buffer_append(&b, p, strlen(p)); 856 break; 857 } 858 } 859 buffer_append(&b, "\0", 1); 860 ret = xstrdup(buffer_ptr(&b)); 861 buffer_free(&b); 862 debug("list_hostkey_types: %s", ret); 863 return ret; 864 } 865 866 static Key * 867 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 868 { 869 int i; 870 Key *key; 871 872 for (i = 0; i < options.num_host_key_files; i++) { 873 switch (type) { 874 case KEY_RSA_CERT: 875 case KEY_DSA_CERT: 876 case KEY_ECDSA_CERT: 877 case KEY_ED25519_CERT: 878 key = sensitive_data.host_certificates[i]; 879 break; 880 default: 881 key = sensitive_data.host_keys[i]; 882 if (key == NULL && !need_private) 883 key = sensitive_data.host_pubkeys[i]; 884 break; 885 } 886 if (key != NULL && key->type == type && 887 (key->type != KEY_ECDSA || key->ecdsa_nid == nid)) 888 return need_private ? 889 sensitive_data.host_keys[i] : key; 890 } 891 return NULL; 892 } 893 894 Key * 895 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 896 { 897 return get_hostkey_by_type(type, nid, 0, ssh); 898 } 899 900 Key * 901 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 902 { 903 return get_hostkey_by_type(type, nid, 1, ssh); 904 } 905 906 Key * 907 get_hostkey_by_index(int ind) 908 { 909 if (ind < 0 || ind >= options.num_host_key_files) 910 return (NULL); 911 return (sensitive_data.host_keys[ind]); 912 } 913 914 Key * 915 get_hostkey_public_by_index(int ind, struct ssh *ssh) 916 { 917 if (ind < 0 || ind >= options.num_host_key_files) 918 return (NULL); 919 return (sensitive_data.host_pubkeys[ind]); 920 } 921 922 int 923 get_hostkey_index(Key *key, int compare, struct ssh *ssh) 924 { 925 int i; 926 927 for (i = 0; i < options.num_host_key_files; i++) { 928 if (key_is_cert(key)) { 929 if (key == sensitive_data.host_certificates[i] || 930 (compare && sensitive_data.host_certificates[i] && 931 sshkey_equal(key, 932 sensitive_data.host_certificates[i]))) 933 return (i); 934 } else { 935 if (key == sensitive_data.host_keys[i] || 936 (compare && sensitive_data.host_keys[i] && 937 sshkey_equal(key, sensitive_data.host_keys[i]))) 938 return (i); 939 if (key == sensitive_data.host_pubkeys[i] || 940 (compare && sensitive_data.host_pubkeys[i] && 941 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 942 return (i); 943 } 944 } 945 return (-1); 946 } 947 948 /* Inform the client of all hostkeys */ 949 static void 950 notify_hostkeys(struct ssh *ssh) 951 { 952 struct sshbuf *buf; 953 struct sshkey *key; 954 int i, nkeys, r; 955 char *fp; 956 957 /* Some clients cannot cope with the hostkeys message, skip those. */ 958 if (datafellows & SSH_BUG_HOSTKEYS) 959 return; 960 961 if ((buf = sshbuf_new()) == NULL) 962 fatal("%s: sshbuf_new", __func__); 963 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 964 key = get_hostkey_public_by_index(i, ssh); 965 if (key == NULL || key->type == KEY_UNSPEC || 966 key->type == KEY_RSA1 || sshkey_is_cert(key)) 967 continue; 968 fp = sshkey_fingerprint(key, options.fingerprint_hash, 969 SSH_FP_DEFAULT); 970 debug3("%s: key %d: %s %s", __func__, i, 971 sshkey_ssh_name(key), fp); 972 free(fp); 973 if (nkeys == 0) { 974 packet_start(SSH2_MSG_GLOBAL_REQUEST); 975 packet_put_cstring("hostkeys-00@openssh.com"); 976 packet_put_char(0); /* want-reply */ 977 } 978 sshbuf_reset(buf); 979 if ((r = sshkey_putb(key, buf)) != 0) 980 fatal("%s: couldn't put hostkey %d: %s", 981 __func__, i, ssh_err(r)); 982 packet_put_string(sshbuf_ptr(buf), sshbuf_len(buf)); 983 nkeys++; 984 } 985 debug3("%s: sent %d hostkeys", __func__, nkeys); 986 if (nkeys == 0) 987 fatal("%s: no hostkeys", __func__); 988 packet_send(); 989 sshbuf_free(buf); 990 } 991 992 /* 993 * returns 1 if connection should be dropped, 0 otherwise. 994 * dropping starts at connection #max_startups_begin with a probability 995 * of (max_startups_rate/100). the probability increases linearly until 996 * all connections are dropped for startups > max_startups 997 */ 998 static int 999 drop_connection(int startups) 1000 { 1001 int p, r; 1002 1003 if (startups < options.max_startups_begin) 1004 return 0; 1005 if (startups >= options.max_startups) 1006 return 1; 1007 if (options.max_startups_rate == 100) 1008 return 1; 1009 1010 p = 100 - options.max_startups_rate; 1011 p *= startups - options.max_startups_begin; 1012 p /= options.max_startups - options.max_startups_begin; 1013 p += options.max_startups_rate; 1014 r = arc4random_uniform(100); 1015 1016 debug("drop_connection: p %d, r %d", p, r); 1017 return (r < p) ? 1 : 0; 1018 } 1019 1020 static void 1021 usage(void) 1022 { 1023 if (options.version_addendum && *options.version_addendum != '\0') 1024 fprintf(stderr, "%s %s, %s\n", 1025 SSH_RELEASE, 1026 options.version_addendum, OPENSSL_VERSION); 1027 else 1028 fprintf(stderr, "%s, %s\n", 1029 SSH_RELEASE, OPENSSL_VERSION); 1030 fprintf(stderr, 1031 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 1032 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 1033 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port]\n" 1034 " [-u len]\n" 1035 ); 1036 exit(1); 1037 } 1038 1039 static void 1040 send_rexec_state(int fd, Buffer *conf) 1041 { 1042 Buffer m; 1043 1044 debug3("%s: entering fd = %d config len %d", __func__, fd, 1045 buffer_len(conf)); 1046 1047 /* 1048 * Protocol from reexec master to child: 1049 * string configuration 1050 * u_int ephemeral_key_follows 1051 * bignum e (only if ephemeral_key_follows == 1) 1052 * bignum n " 1053 * bignum d " 1054 * bignum iqmp " 1055 * bignum p " 1056 * bignum q " 1057 * string rngseed (only if OpenSSL is not self-seeded) 1058 */ 1059 buffer_init(&m); 1060 buffer_put_cstring(&m, buffer_ptr(conf)); 1061 1062 #ifdef WITH_SSH1 1063 if (sensitive_data.server_key != NULL && 1064 sensitive_data.server_key->type == KEY_RSA1) { 1065 buffer_put_int(&m, 1); 1066 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 1067 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 1068 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 1069 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 1070 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 1071 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 1072 } else 1073 #endif 1074 buffer_put_int(&m, 0); 1075 1076 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 1077 rexec_send_rng_seed(&m); 1078 #endif 1079 1080 if (ssh_msg_send(fd, 0, &m) == -1) 1081 fatal("%s: ssh_msg_send failed", __func__); 1082 1083 buffer_free(&m); 1084 1085 debug3("%s: done", __func__); 1086 } 1087 1088 static void 1089 recv_rexec_state(int fd, Buffer *conf) 1090 { 1091 Buffer m; 1092 char *cp; 1093 u_int len; 1094 1095 debug3("%s: entering fd = %d", __func__, fd); 1096 1097 buffer_init(&m); 1098 1099 if (ssh_msg_recv(fd, &m) == -1) 1100 fatal("%s: ssh_msg_recv failed", __func__); 1101 if (buffer_get_char(&m) != 0) 1102 fatal("%s: rexec version mismatch", __func__); 1103 1104 cp = buffer_get_string(&m, &len); 1105 if (conf != NULL) 1106 buffer_append(conf, cp, len + 1); 1107 free(cp); 1108 1109 if (buffer_get_int(&m)) { 1110 #ifdef WITH_SSH1 1111 if (sensitive_data.server_key != NULL) 1112 key_free(sensitive_data.server_key); 1113 sensitive_data.server_key = key_new_private(KEY_RSA1); 1114 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 1115 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 1116 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 1117 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 1118 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 1119 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 1120 if (rsa_generate_additional_parameters( 1121 sensitive_data.server_key->rsa) != 0) 1122 fatal("%s: rsa_generate_additional_parameters " 1123 "error", __func__); 1124 #endif 1125 } 1126 1127 #if defined(WITH_OPENSSL) && !defined(OPENSSL_PRNG_ONLY) 1128 rexec_recv_rng_seed(&m); 1129 #endif 1130 1131 buffer_free(&m); 1132 1133 debug3("%s: done", __func__); 1134 } 1135 1136 /* Accept a connection from inetd */ 1137 static void 1138 server_accept_inetd(int *sock_in, int *sock_out) 1139 { 1140 int fd; 1141 1142 startup_pipe = -1; 1143 if (rexeced_flag) { 1144 close(REEXEC_CONFIG_PASS_FD); 1145 *sock_in = *sock_out = dup(STDIN_FILENO); 1146 if (!debug_flag) { 1147 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1148 close(REEXEC_STARTUP_PIPE_FD); 1149 } 1150 } else { 1151 *sock_in = dup(STDIN_FILENO); 1152 *sock_out = dup(STDOUT_FILENO); 1153 } 1154 /* 1155 * We intentionally do not close the descriptors 0, 1, and 2 1156 * as our code for setting the descriptors won't work if 1157 * ttyfd happens to be one of those. 1158 */ 1159 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1160 dup2(fd, STDIN_FILENO); 1161 dup2(fd, STDOUT_FILENO); 1162 if (!log_stderr) 1163 dup2(fd, STDERR_FILENO); 1164 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1165 close(fd); 1166 } 1167 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1168 } 1169 1170 /* 1171 * Listen for TCP connections 1172 */ 1173 static void 1174 server_listen(void) 1175 { 1176 int ret, listen_sock, on = 1; 1177 struct addrinfo *ai; 1178 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1179 int socksize; 1180 socklen_t len; 1181 1182 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1183 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1184 continue; 1185 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1186 fatal("Too many listen sockets. " 1187 "Enlarge MAX_LISTEN_SOCKS"); 1188 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1189 ntop, sizeof(ntop), strport, sizeof(strport), 1190 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1191 error("getnameinfo failed: %.100s", 1192 ssh_gai_strerror(ret)); 1193 continue; 1194 } 1195 /* Create socket for listening. */ 1196 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1197 ai->ai_protocol); 1198 if (listen_sock < 0) { 1199 /* kernel may not support ipv6 */ 1200 verbose("socket: %.100s", strerror(errno)); 1201 continue; 1202 } 1203 if (set_nonblock(listen_sock) == -1) { 1204 close(listen_sock); 1205 continue; 1206 } 1207 /* 1208 * Set socket options. 1209 * Allow local port reuse in TIME_WAIT. 1210 */ 1211 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1212 &on, sizeof(on)) == -1) 1213 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1214 1215 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1216 if (ai->ai_family == AF_INET6) 1217 sock_set_v6only(listen_sock); 1218 1219 debug("Bind to port %s on %s.", strport, ntop); 1220 1221 len = sizeof(socksize); 1222 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len); 1223 debug("Server TCP RWIN socket size: %d", socksize); 1224 1225 /* Bind the socket to the desired port. */ 1226 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1227 error("Bind to port %s on %s failed: %.200s.", 1228 strport, ntop, strerror(errno)); 1229 close(listen_sock); 1230 continue; 1231 } 1232 listen_socks[num_listen_socks] = listen_sock; 1233 num_listen_socks++; 1234 1235 /* Start listening on the port. */ 1236 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1237 fatal("listen on [%s]:%s: %.100s", 1238 ntop, strport, strerror(errno)); 1239 logit("Server listening on %s port %s.", ntop, strport); 1240 } 1241 freeaddrinfo(options.listen_addrs); 1242 1243 if (!num_listen_socks) 1244 fatal("Cannot bind any address."); 1245 } 1246 1247 /* 1248 * The main TCP accept loop. Note that, for the non-debug case, returns 1249 * from this function are in a forked subprocess. 1250 */ 1251 static void 1252 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1253 { 1254 fd_set *fdset; 1255 int i, j, ret, maxfd; 1256 int key_used = 0, startups = 0; 1257 int startup_p[2] = { -1 , -1 }; 1258 struct sockaddr_storage from; 1259 socklen_t fromlen; 1260 pid_t pid; 1261 u_char rnd[256]; 1262 1263 /* setup fd set for accept */ 1264 fdset = NULL; 1265 maxfd = 0; 1266 for (i = 0; i < num_listen_socks; i++) 1267 if (listen_socks[i] > maxfd) 1268 maxfd = listen_socks[i]; 1269 /* pipes connected to unauthenticated childs */ 1270 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1271 for (i = 0; i < options.max_startups; i++) 1272 startup_pipes[i] = -1; 1273 1274 /* 1275 * Stay listening for connections until the system crashes or 1276 * the daemon is killed with a signal. 1277 */ 1278 for (;;) { 1279 if (received_sighup) 1280 sighup_restart(); 1281 if (fdset != NULL) 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 #ifdef HAVE_SECUREWARE 1503 (void)set_auth_parameters(ac, av); 1504 #endif 1505 __progname = ssh_get_progname(av[0]); 1506 1507 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1508 saved_argc = ac; 1509 rexec_argc = ac; 1510 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1511 for (i = 0; i < ac; i++) 1512 saved_argv[i] = xstrdup(av[i]); 1513 saved_argv[i] = NULL; 1514 1515 #ifndef HAVE_SETPROCTITLE 1516 /* Prepare for later setproctitle emulation */ 1517 compat_init_setproctitle(ac, av); 1518 av = saved_argv; 1519 #endif 1520 1521 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1522 debug("setgroups(): %.200s", strerror(errno)); 1523 1524 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1525 sanitise_stdfd(); 1526 1527 /* Initialize configuration options to their default values. */ 1528 initialize_server_options(&options); 1529 1530 /* Parse command-line arguments. */ 1531 while ((opt = getopt(ac, av, 1532 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1533 switch (opt) { 1534 case '4': 1535 options.address_family = AF_INET; 1536 break; 1537 case '6': 1538 options.address_family = AF_INET6; 1539 break; 1540 case 'f': 1541 config_file_name = optarg; 1542 break; 1543 case 'c': 1544 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1545 fprintf(stderr, "too many host certificates.\n"); 1546 exit(1); 1547 } 1548 options.host_cert_files[options.num_host_cert_files++] = 1549 derelativise_path(optarg); 1550 break; 1551 case 'd': 1552 if (debug_flag == 0) { 1553 debug_flag = 1; 1554 options.log_level = SYSLOG_LEVEL_DEBUG1; 1555 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1556 options.log_level++; 1557 break; 1558 case 'D': 1559 no_daemon_flag = 1; 1560 break; 1561 case 'E': 1562 logfile = xstrdup(optarg); 1563 /* FALLTHROUGH */ 1564 case 'e': 1565 log_stderr = 1; 1566 break; 1567 case 'i': 1568 inetd_flag = 1; 1569 break; 1570 case 'r': 1571 rexec_flag = 0; 1572 break; 1573 case 'R': 1574 rexeced_flag = 1; 1575 inetd_flag = 1; 1576 break; 1577 case 'Q': 1578 /* ignored */ 1579 break; 1580 case 'q': 1581 options.log_level = SYSLOG_LEVEL_QUIET; 1582 break; 1583 case 'b': 1584 options.server_key_bits = (int)strtonum(optarg, 256, 1585 32768, NULL); 1586 break; 1587 case 'p': 1588 options.ports_from_cmdline = 1; 1589 if (options.num_ports >= MAX_PORTS) { 1590 fprintf(stderr, "too many ports.\n"); 1591 exit(1); 1592 } 1593 options.ports[options.num_ports++] = a2port(optarg); 1594 if (options.ports[options.num_ports-1] <= 0) { 1595 fprintf(stderr, "Bad port number.\n"); 1596 exit(1); 1597 } 1598 break; 1599 case 'g': 1600 if ((options.login_grace_time = convtime(optarg)) == -1) { 1601 fprintf(stderr, "Invalid login grace time.\n"); 1602 exit(1); 1603 } 1604 break; 1605 case 'k': 1606 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1607 fprintf(stderr, "Invalid key regeneration interval.\n"); 1608 exit(1); 1609 } 1610 break; 1611 case 'h': 1612 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1613 fprintf(stderr, "too many host keys.\n"); 1614 exit(1); 1615 } 1616 options.host_key_files[options.num_host_key_files++] = 1617 derelativise_path(optarg); 1618 break; 1619 case 't': 1620 test_flag = 1; 1621 break; 1622 case 'T': 1623 test_flag = 2; 1624 break; 1625 case 'C': 1626 if (parse_server_match_testspec(connection_info, 1627 optarg) == -1) 1628 exit(1); 1629 break; 1630 case 'u': 1631 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1632 if (utmp_len > HOST_NAME_MAX+1) { 1633 fprintf(stderr, "Invalid utmp length.\n"); 1634 exit(1); 1635 } 1636 break; 1637 case 'o': 1638 line = xstrdup(optarg); 1639 if (process_server_config_line(&options, line, 1640 "command-line", 0, NULL, NULL) != 0) 1641 exit(1); 1642 free(line); 1643 break; 1644 case '?': 1645 default: 1646 usage(); 1647 break; 1648 } 1649 } 1650 if (rexeced_flag || inetd_flag) 1651 rexec_flag = 0; 1652 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1653 fatal("sshd re-exec requires execution with an absolute path"); 1654 if (rexeced_flag) 1655 closefrom(REEXEC_MIN_FREE_FD); 1656 else 1657 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1658 1659 #ifdef WITH_OPENSSL 1660 OpenSSL_add_all_algorithms(); 1661 #endif 1662 1663 /* If requested, redirect the logs to the specified logfile. */ 1664 if (logfile != NULL) { 1665 log_redirect_stderr_to(logfile); 1666 free(logfile); 1667 } 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, 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) < 0)) 2591 fatal("%s: key_sign failed", __func__); 2592 if (slen) 2593 *slen = xxx_slen; 2594 } else if (use_privsep) { 2595 if (mm_key_sign(pubkey, signature, &xxx_slen, data, xxx_dlen) < 0) 2596 fatal("%s: pubkey_sign failed", __func__); 2597 if (slen) 2598 *slen = xxx_slen; 2599 } else { 2600 if ((r = ssh_agent_sign(auth_sock, pubkey, signature, slen, 2601 data, dlen, datafellows)) != 0) 2602 fatal("%s: ssh_agent_sign failed: %s", 2603 __func__, ssh_err(r)); 2604 } 2605 return 0; 2606 } 2607 2608 /* SSH2 key exchange */ 2609 static void 2610 do_ssh2_kex(void) 2611 { 2612 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2613 struct kex *kex; 2614 int r; 2615 2616 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2617 options.kex_algorithms); 2618 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2619 options.ciphers); 2620 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2621 options.ciphers); 2622 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2623 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2624 2625 if (options.compression == COMP_NONE) { 2626 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2627 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2628 } else if (options.compression == COMP_DELAYED) { 2629 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2630 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2631 } 2632 2633 if (options.rekey_limit || options.rekey_interval) 2634 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 2635 (time_t)options.rekey_interval); 2636 2637 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2638 list_hostkey_types()); 2639 2640 /* start key exchange */ 2641 if ((r = kex_setup(active_state, myproposal)) != 0) 2642 fatal("kex_setup: %s", ssh_err(r)); 2643 kex = active_state->kex; 2644 #ifdef WITH_OPENSSL 2645 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2646 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2647 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2648 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2649 # ifdef OPENSSL_HAS_ECC 2650 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2651 # endif 2652 #endif 2653 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2654 kex->server = 1; 2655 kex->client_version_string=client_version_string; 2656 kex->server_version_string=server_version_string; 2657 kex->load_host_public_key=&get_hostkey_public_by_type; 2658 kex->load_host_private_key=&get_hostkey_private_by_type; 2659 kex->host_key_index=&get_hostkey_index; 2660 kex->sign = sshd_hostkey_sign; 2661 2662 dispatch_run(DISPATCH_BLOCK, &kex->done, active_state); 2663 2664 session_id2 = kex->session_id; 2665 session_id2_len = kex->session_id_len; 2666 2667 #ifdef DEBUG_KEXDH 2668 /* send 1st encrypted/maced/compressed message */ 2669 packet_start(SSH2_MSG_IGNORE); 2670 packet_put_cstring("markus"); 2671 packet_send(); 2672 packet_write_wait(); 2673 #endif 2674 debug("KEX done"); 2675 } 2676 2677 /* server specific fatal cleanup */ 2678 void 2679 cleanup_exit(int i) 2680 { 2681 if (the_authctxt) { 2682 do_cleanup(the_authctxt); 2683 if (use_privsep && privsep_is_preauth && 2684 pmonitor != NULL && pmonitor->m_pid > 1) { 2685 debug("Killing privsep child %d", pmonitor->m_pid); 2686 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2687 errno != ESRCH) 2688 error("%s: kill(%d): %s", __func__, 2689 pmonitor->m_pid, strerror(errno)); 2690 } 2691 } 2692 #ifdef SSH_AUDIT_EVENTS 2693 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2694 if (!use_privsep || mm_is_monitor()) 2695 audit_event(SSH_CONNECTION_ABANDON); 2696 #endif 2697 _exit(i); 2698 } 2699