1 /* $OpenBSD: sshd.c,v 1.367 2009/05/28 16:50:16 andreas 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 <sys/types.h> 46 #include <sys/ioctl.h> 47 #include <sys/wait.h> 48 #include <sys/tree.h> 49 #include <sys/stat.h> 50 #include <sys/socket.h> 51 #include <sys/time.h> 52 #include <sys/queue.h> 53 54 #include <errno.h> 55 #include <fcntl.h> 56 #include <netdb.h> 57 #include <paths.h> 58 #include <pwd.h> 59 #include <signal.h> 60 #include <stdio.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <unistd.h> 64 65 #include <openssl/dh.h> 66 #include <openssl/bn.h> 67 #include <openssl/md5.h> 68 #include <openssl/rand.h> 69 70 #include "xmalloc.h" 71 #include "ssh.h" 72 #include "ssh1.h" 73 #include "ssh2.h" 74 #include "rsa.h" 75 #include "sshpty.h" 76 #include "packet.h" 77 #include "log.h" 78 #include "buffer.h" 79 #include "servconf.h" 80 #include "uidswap.h" 81 #include "compat.h" 82 #include "cipher.h" 83 #include "key.h" 84 #include "kex.h" 85 #include "dh.h" 86 #include "myproposal.h" 87 #include "authfile.h" 88 #include "pathnames.h" 89 #include "atomicio.h" 90 #include "canohost.h" 91 #include "hostfile.h" 92 #include "auth.h" 93 #include "misc.h" 94 #include "msg.h" 95 #include "dispatch.h" 96 #include "channels.h" 97 #include "session.h" 98 #include "monitor_mm.h" 99 #include "monitor.h" 100 #ifdef GSSAPI 101 #include "ssh-gss.h" 102 #endif 103 #include "monitor_wrap.h" 104 #include "roaming.h" 105 #include "version.h" 106 107 #ifdef LIBWRAP 108 #include <tcpd.h> 109 #include <syslog.h> 110 int allow_severity = LOG_INFO; 111 int deny_severity = LOG_WARNING; 112 #endif /* LIBWRAP */ 113 114 #ifndef O_NOCTTY 115 #define O_NOCTTY 0 116 #endif 117 118 /* Re-exec fds */ 119 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 120 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 121 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 122 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 123 124 extern char *__progname; 125 126 /* Server configuration options. */ 127 ServerOptions options; 128 129 /* Name of the server configuration file. */ 130 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 131 132 /* 133 * Debug mode flag. This can be set on the command line. If debug 134 * mode is enabled, extra debugging output will be sent to the system 135 * log, the daemon will not go to background, and will exit after processing 136 * the first connection. 137 */ 138 int debug_flag = 0; 139 140 /* Flag indicating that the daemon should only test the configuration and keys. */ 141 int test_flag = 0; 142 143 /* Flag indicating that the daemon is being started from inetd. */ 144 int inetd_flag = 0; 145 146 /* Flag indicating that sshd should not detach and become a daemon. */ 147 int no_daemon_flag = 0; 148 149 /* debug goes to stderr unless inetd_flag is set */ 150 int log_stderr = 0; 151 152 /* Saved arguments to main(). */ 153 char **saved_argv; 154 155 /* re-exec */ 156 int rexeced_flag = 0; 157 int rexec_flag = 1; 158 int rexec_argc = 0; 159 char **rexec_argv; 160 161 /* 162 * The sockets that the server is listening; this is used in the SIGHUP 163 * signal handler. 164 */ 165 #define MAX_LISTEN_SOCKS 16 166 int listen_socks[MAX_LISTEN_SOCKS]; 167 int num_listen_socks = 0; 168 169 /* 170 * the client's version string, passed by sshd2 in compat mode. if != NULL, 171 * sshd will skip the version-number exchange 172 */ 173 char *client_version_string = NULL; 174 char *server_version_string = NULL; 175 176 /* for rekeying XXX fixme */ 177 Kex *xxx_kex; 178 179 /* 180 * Any really sensitive data in the application is contained in this 181 * structure. The idea is that this structure could be locked into memory so 182 * that the pages do not get written into swap. However, there are some 183 * problems. The private key contains BIGNUMs, and we do not (in principle) 184 * have access to the internals of them, and locking just the structure is 185 * not very useful. Currently, memory locking is not implemented. 186 */ 187 struct { 188 Key *server_key; /* ephemeral server key */ 189 Key *ssh1_host_key; /* ssh1 host key */ 190 Key **host_keys; /* all private host keys */ 191 int have_ssh1_key; 192 int have_ssh2_key; 193 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 194 } sensitive_data; 195 196 /* 197 * Flag indicating whether the RSA server key needs to be regenerated. 198 * Is set in the SIGALRM handler and cleared when the key is regenerated. 199 */ 200 static volatile sig_atomic_t key_do_regen = 0; 201 202 /* This is set to true when a signal is received. */ 203 static volatile sig_atomic_t received_sighup = 0; 204 static volatile sig_atomic_t received_sigterm = 0; 205 206 /* session identifier, used by RSA-auth */ 207 u_char session_id[16]; 208 209 /* same for ssh2 */ 210 u_char *session_id2 = NULL; 211 u_int session_id2_len = 0; 212 213 /* record remote hostname or ip */ 214 u_int utmp_len = MAXHOSTNAMELEN; 215 216 /* options.max_startup sized array of fd ints */ 217 int *startup_pipes = NULL; 218 int startup_pipe; /* in child */ 219 220 /* variables used for privilege separation */ 221 int use_privsep = -1; 222 struct monitor *pmonitor = NULL; 223 224 /* global authentication context */ 225 Authctxt *the_authctxt = NULL; 226 227 /* sshd_config buffer */ 228 Buffer cfg; 229 230 /* message to be displayed after login */ 231 Buffer loginmsg; 232 233 /* Prototypes for various functions defined later in this file. */ 234 void destroy_sensitive_data(void); 235 void demote_sensitive_data(void); 236 237 static void do_ssh1_kex(void); 238 static void do_ssh2_kex(void); 239 240 /* 241 * Close all listening sockets 242 */ 243 static void 244 close_listen_socks(void) 245 { 246 int i; 247 248 for (i = 0; i < num_listen_socks; i++) 249 close(listen_socks[i]); 250 num_listen_socks = -1; 251 } 252 253 static void 254 close_startup_pipes(void) 255 { 256 int i; 257 258 if (startup_pipes) 259 for (i = 0; i < options.max_startups; i++) 260 if (startup_pipes[i] != -1) 261 close(startup_pipes[i]); 262 } 263 264 /* 265 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 266 * the effect is to reread the configuration file (and to regenerate 267 * the server key). 268 */ 269 270 /*ARGSUSED*/ 271 static void 272 sighup_handler(int sig) 273 { 274 int save_errno = errno; 275 276 received_sighup = 1; 277 signal(SIGHUP, sighup_handler); 278 errno = save_errno; 279 } 280 281 /* 282 * Called from the main program after receiving SIGHUP. 283 * Restarts the server. 284 */ 285 static void 286 sighup_restart(void) 287 { 288 logit("Received SIGHUP; restarting."); 289 close_listen_socks(); 290 close_startup_pipes(); 291 alarm(0); /* alarm timer persists across exec */ 292 execv(saved_argv[0], saved_argv); 293 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 294 strerror(errno)); 295 exit(1); 296 } 297 298 /* 299 * Generic signal handler for terminating signals in the master daemon. 300 */ 301 /*ARGSUSED*/ 302 static void 303 sigterm_handler(int sig) 304 { 305 received_sigterm = sig; 306 } 307 308 /* 309 * SIGCHLD handler. This is called whenever a child dies. This will then 310 * reap any zombies left by exited children. 311 */ 312 /*ARGSUSED*/ 313 static void 314 main_sigchld_handler(int sig) 315 { 316 int save_errno = errno; 317 pid_t pid; 318 int status; 319 320 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 321 (pid < 0 && errno == EINTR)) 322 ; 323 324 signal(SIGCHLD, main_sigchld_handler); 325 errno = save_errno; 326 } 327 328 /* 329 * Signal handler for the alarm after the login grace period has expired. 330 */ 331 /*ARGSUSED*/ 332 static void 333 grace_alarm_handler(int sig) 334 { 335 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 336 kill(pmonitor->m_pid, SIGALRM); 337 338 /* Log error and exit. */ 339 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 340 } 341 342 /* 343 * Signal handler for the key regeneration alarm. Note that this 344 * alarm only occurs in the daemon waiting for connections, and it does not 345 * do anything with the private key or random state before forking. 346 * Thus there should be no concurrency control/asynchronous execution 347 * problems. 348 */ 349 static void 350 generate_ephemeral_server_key(void) 351 { 352 verbose("Generating %s%d bit RSA key.", 353 sensitive_data.server_key ? "new " : "", options.server_key_bits); 354 if (sensitive_data.server_key != NULL) 355 key_free(sensitive_data.server_key); 356 sensitive_data.server_key = key_generate(KEY_RSA1, 357 options.server_key_bits); 358 verbose("RSA key generation complete."); 359 360 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 361 arc4random_stir(); 362 } 363 364 /*ARGSUSED*/ 365 static void 366 key_regeneration_alarm(int sig) 367 { 368 int save_errno = errno; 369 370 signal(SIGALRM, SIG_DFL); 371 errno = save_errno; 372 key_do_regen = 1; 373 } 374 375 static void 376 sshd_exchange_identification(int sock_in, int sock_out) 377 { 378 u_int i; 379 int mismatch; 380 int remote_major, remote_minor; 381 int major, minor; 382 char *s, *newline = "\n"; 383 char buf[256]; /* Must not be larger than remote_version. */ 384 char remote_version[256]; /* Must be at least as big as buf. */ 385 386 if ((options.protocol & SSH_PROTO_1) && 387 (options.protocol & SSH_PROTO_2)) { 388 major = PROTOCOL_MAJOR_1; 389 minor = 99; 390 } else if (options.protocol & SSH_PROTO_2) { 391 major = PROTOCOL_MAJOR_2; 392 minor = PROTOCOL_MINOR_2; 393 newline = "\r\n"; 394 } else { 395 major = PROTOCOL_MAJOR_1; 396 minor = PROTOCOL_MINOR_1; 397 } 398 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor, 399 SSH_VERSION, newline); 400 server_version_string = xstrdup(buf); 401 402 /* Send our protocol version identification. */ 403 if (roaming_atomicio(vwrite, sock_out, server_version_string, 404 strlen(server_version_string)) 405 != strlen(server_version_string)) { 406 logit("Could not write ident string to %s", get_remote_ipaddr()); 407 cleanup_exit(255); 408 } 409 410 /* Read other sides version identification. */ 411 memset(buf, 0, sizeof(buf)); 412 for (i = 0; i < sizeof(buf) - 1; i++) { 413 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 414 logit("Did not receive identification string from %s", 415 get_remote_ipaddr()); 416 cleanup_exit(255); 417 } 418 if (buf[i] == '\r') { 419 buf[i] = 0; 420 /* Kludge for F-Secure Macintosh < 1.0.2 */ 421 if (i == 12 && 422 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 423 break; 424 continue; 425 } 426 if (buf[i] == '\n') { 427 buf[i] = 0; 428 break; 429 } 430 } 431 buf[sizeof(buf) - 1] = 0; 432 client_version_string = xstrdup(buf); 433 434 /* 435 * Check that the versions match. In future this might accept 436 * several versions and set appropriate flags to handle them. 437 */ 438 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 439 &remote_major, &remote_minor, remote_version) != 3) { 440 s = "Protocol mismatch.\n"; 441 (void) atomicio(vwrite, sock_out, s, strlen(s)); 442 close(sock_in); 443 close(sock_out); 444 logit("Bad protocol version identification '%.100s' from %s", 445 client_version_string, get_remote_ipaddr()); 446 cleanup_exit(255); 447 } 448 debug("Client protocol version %d.%d; client software version %.100s", 449 remote_major, remote_minor, remote_version); 450 451 compat_datafellows(remote_version); 452 453 if (datafellows & SSH_BUG_PROBE) { 454 logit("probed from %s with %s. Don't panic.", 455 get_remote_ipaddr(), client_version_string); 456 cleanup_exit(255); 457 } 458 459 if (datafellows & SSH_BUG_SCANNER) { 460 logit("scanned from %s with %s. Don't panic.", 461 get_remote_ipaddr(), client_version_string); 462 cleanup_exit(255); 463 } 464 465 mismatch = 0; 466 switch (remote_major) { 467 case 1: 468 if (remote_minor == 99) { 469 if (options.protocol & SSH_PROTO_2) 470 enable_compat20(); 471 else 472 mismatch = 1; 473 break; 474 } 475 if (!(options.protocol & SSH_PROTO_1)) { 476 mismatch = 1; 477 break; 478 } 479 if (remote_minor < 3) { 480 packet_disconnect("Your ssh version is too old and " 481 "is no longer supported. Please install a newer version."); 482 } else if (remote_minor == 3) { 483 /* note that this disables agent-forwarding */ 484 enable_compat13(); 485 } 486 break; 487 case 2: 488 if (options.protocol & SSH_PROTO_2) { 489 enable_compat20(); 490 break; 491 } 492 /* FALLTHROUGH */ 493 default: 494 mismatch = 1; 495 break; 496 } 497 chop(server_version_string); 498 debug("Local version string %.200s", server_version_string); 499 500 if (mismatch) { 501 s = "Protocol major versions differ.\n"; 502 (void) atomicio(vwrite, sock_out, s, strlen(s)); 503 close(sock_in); 504 close(sock_out); 505 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 506 get_remote_ipaddr(), 507 server_version_string, client_version_string); 508 cleanup_exit(255); 509 } 510 } 511 512 /* Destroy the host and server keys. They will no longer be needed. */ 513 void 514 destroy_sensitive_data(void) 515 { 516 int i; 517 518 if (sensitive_data.server_key) { 519 key_free(sensitive_data.server_key); 520 sensitive_data.server_key = NULL; 521 } 522 for (i = 0; i < options.num_host_key_files; i++) { 523 if (sensitive_data.host_keys[i]) { 524 key_free(sensitive_data.host_keys[i]); 525 sensitive_data.host_keys[i] = NULL; 526 } 527 } 528 sensitive_data.ssh1_host_key = NULL; 529 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); 530 } 531 532 /* Demote private to public keys for network child */ 533 void 534 demote_sensitive_data(void) 535 { 536 Key *tmp; 537 int i; 538 539 if (sensitive_data.server_key) { 540 tmp = key_demote(sensitive_data.server_key); 541 key_free(sensitive_data.server_key); 542 sensitive_data.server_key = tmp; 543 } 544 545 for (i = 0; i < options.num_host_key_files; i++) { 546 if (sensitive_data.host_keys[i]) { 547 tmp = key_demote(sensitive_data.host_keys[i]); 548 key_free(sensitive_data.host_keys[i]); 549 sensitive_data.host_keys[i] = tmp; 550 if (tmp->type == KEY_RSA1) 551 sensitive_data.ssh1_host_key = tmp; 552 } 553 } 554 555 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 556 } 557 558 static void 559 privsep_preauth_child(void) 560 { 561 u_int32_t rnd[256]; 562 gid_t gidset[1]; 563 struct passwd *pw; 564 565 /* Enable challenge-response authentication for privilege separation */ 566 privsep_challenge_enable(); 567 568 arc4random_stir(); 569 arc4random_buf(rnd, sizeof(rnd)); 570 RAND_seed(rnd, sizeof(rnd)); 571 572 /* Demote the private keys to public keys. */ 573 demote_sensitive_data(); 574 575 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) 576 fatal("Privilege separation user %s does not exist", 577 SSH_PRIVSEP_USER); 578 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); 579 endpwent(); 580 581 /* Change our root directory */ 582 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 583 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 584 strerror(errno)); 585 if (chdir("/") == -1) 586 fatal("chdir(\"/\"): %s", strerror(errno)); 587 588 /* Drop our privileges */ 589 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, 590 (u_int)pw->pw_gid); 591 #if 0 592 /* XXX not ready, too heavy after chroot */ 593 do_setusercontext(pw); 594 #else 595 gidset[0] = pw->pw_gid; 596 if (setgroups(1, gidset) < 0) 597 fatal("setgroups: %.100s", strerror(errno)); 598 permanently_set_uid(pw); 599 #endif 600 } 601 602 static int 603 privsep_preauth(Authctxt *authctxt) 604 { 605 int status; 606 pid_t pid; 607 608 /* Set up unprivileged child process to deal with network data */ 609 pmonitor = monitor_init(); 610 /* Store a pointer to the kex for later rekeying */ 611 pmonitor->m_pkex = &xxx_kex; 612 613 pid = fork(); 614 if (pid == -1) { 615 fatal("fork of unprivileged child failed"); 616 } else if (pid != 0) { 617 debug2("Network child is on pid %ld", (long)pid); 618 619 close(pmonitor->m_recvfd); 620 pmonitor->m_pid = pid; 621 monitor_child_preauth(authctxt, pmonitor); 622 close(pmonitor->m_sendfd); 623 624 /* Sync memory */ 625 monitor_sync(pmonitor); 626 627 /* Wait for the child's exit status */ 628 while (waitpid(pid, &status, 0) < 0) 629 if (errno != EINTR) 630 break; 631 return (1); 632 } else { 633 /* child */ 634 635 close(pmonitor->m_sendfd); 636 637 /* Demote the child */ 638 if (getuid() == 0 || geteuid() == 0) 639 privsep_preauth_child(); 640 setproctitle("%s", "[net]"); 641 } 642 return (0); 643 } 644 645 static void 646 privsep_postauth(Authctxt *authctxt) 647 { 648 u_int32_t rnd[256]; 649 650 if (authctxt->pw->pw_uid == 0 || options.use_login) { 651 /* File descriptor passing is broken or root login */ 652 use_privsep = 0; 653 goto skip; 654 } 655 656 /* New socket pair */ 657 monitor_reinit(pmonitor); 658 659 pmonitor->m_pid = fork(); 660 if (pmonitor->m_pid == -1) 661 fatal("fork of unprivileged child failed"); 662 else if (pmonitor->m_pid != 0) { 663 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 664 close(pmonitor->m_recvfd); 665 buffer_clear(&loginmsg); 666 monitor_child_postauth(pmonitor); 667 668 /* NEVERREACHED */ 669 exit(0); 670 } 671 672 close(pmonitor->m_sendfd); 673 674 /* Demote the private keys to public keys. */ 675 demote_sensitive_data(); 676 677 arc4random_stir(); 678 arc4random_buf(rnd, sizeof(rnd)); 679 RAND_seed(rnd, sizeof(rnd)); 680 681 /* Drop privileges */ 682 do_setusercontext(authctxt->pw); 683 684 skip: 685 /* It is safe now to apply the key state */ 686 monitor_apply_keystate(pmonitor); 687 688 /* 689 * Tell the packet layer that authentication was successful, since 690 * this information is not part of the key state. 691 */ 692 packet_set_authenticated(); 693 } 694 695 static char * 696 list_hostkey_types(void) 697 { 698 Buffer b; 699 const char *p; 700 char *ret; 701 int i; 702 703 buffer_init(&b); 704 for (i = 0; i < options.num_host_key_files; i++) { 705 Key *key = sensitive_data.host_keys[i]; 706 if (key == NULL) 707 continue; 708 switch (key->type) { 709 case KEY_RSA: 710 case KEY_DSA: 711 if (buffer_len(&b) > 0) 712 buffer_append(&b, ",", 1); 713 p = key_ssh_name(key); 714 buffer_append(&b, p, strlen(p)); 715 break; 716 } 717 } 718 buffer_append(&b, "\0", 1); 719 ret = xstrdup(buffer_ptr(&b)); 720 buffer_free(&b); 721 debug("list_hostkey_types: %s", ret); 722 return ret; 723 } 724 725 Key * 726 get_hostkey_by_type(int type) 727 { 728 int i; 729 730 for (i = 0; i < options.num_host_key_files; i++) { 731 Key *key = sensitive_data.host_keys[i]; 732 if (key != NULL && key->type == type) 733 return key; 734 } 735 return NULL; 736 } 737 738 Key * 739 get_hostkey_by_index(int ind) 740 { 741 if (ind < 0 || ind >= options.num_host_key_files) 742 return (NULL); 743 return (sensitive_data.host_keys[ind]); 744 } 745 746 int 747 get_hostkey_index(Key *key) 748 { 749 int i; 750 751 for (i = 0; i < options.num_host_key_files; i++) { 752 if (key == sensitive_data.host_keys[i]) 753 return (i); 754 } 755 return (-1); 756 } 757 758 /* 759 * returns 1 if connection should be dropped, 0 otherwise. 760 * dropping starts at connection #max_startups_begin with a probability 761 * of (max_startups_rate/100). the probability increases linearly until 762 * all connections are dropped for startups > max_startups 763 */ 764 static int 765 drop_connection(int startups) 766 { 767 int p, r; 768 769 if (startups < options.max_startups_begin) 770 return 0; 771 if (startups >= options.max_startups) 772 return 1; 773 if (options.max_startups_rate == 100) 774 return 1; 775 776 p = 100 - options.max_startups_rate; 777 p *= startups - options.max_startups_begin; 778 p /= options.max_startups - options.max_startups_begin; 779 p += options.max_startups_rate; 780 r = arc4random_uniform(100); 781 782 debug("drop_connection: p %d, r %d", p, r); 783 return (r < p) ? 1 : 0; 784 } 785 786 static void 787 usage(void) 788 { 789 fprintf(stderr, "%s, %s\n", 790 SSH_VERSION, SSLeay_version(SSLEAY_VERSION)); 791 fprintf(stderr, 792 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-f config_file]\n" 793 " [-g login_grace_time] [-h host_key_file] [-k key_gen_time]\n" 794 " [-o option] [-p port] [-u len]\n" 795 ); 796 exit(1); 797 } 798 799 static void 800 send_rexec_state(int fd, Buffer *conf) 801 { 802 Buffer m; 803 804 debug3("%s: entering fd = %d config len %d", __func__, fd, 805 buffer_len(conf)); 806 807 /* 808 * Protocol from reexec master to child: 809 * string configuration 810 * u_int ephemeral_key_follows 811 * bignum e (only if ephemeral_key_follows == 1) 812 * bignum n " 813 * bignum d " 814 * bignum iqmp " 815 * bignum p " 816 * bignum q " 817 */ 818 buffer_init(&m); 819 buffer_put_cstring(&m, buffer_ptr(conf)); 820 821 if (sensitive_data.server_key != NULL && 822 sensitive_data.server_key->type == KEY_RSA1) { 823 buffer_put_int(&m, 1); 824 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 825 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 826 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 827 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 828 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 829 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 830 } else 831 buffer_put_int(&m, 0); 832 833 if (ssh_msg_send(fd, 0, &m) == -1) 834 fatal("%s: ssh_msg_send failed", __func__); 835 836 buffer_free(&m); 837 838 debug3("%s: done", __func__); 839 } 840 841 static void 842 recv_rexec_state(int fd, Buffer *conf) 843 { 844 Buffer m; 845 char *cp; 846 u_int len; 847 848 debug3("%s: entering fd = %d", __func__, fd); 849 850 buffer_init(&m); 851 852 if (ssh_msg_recv(fd, &m) == -1) 853 fatal("%s: ssh_msg_recv failed", __func__); 854 if (buffer_get_char(&m) != 0) 855 fatal("%s: rexec version mismatch", __func__); 856 857 cp = buffer_get_string(&m, &len); 858 if (conf != NULL) 859 buffer_append(conf, cp, len + 1); 860 xfree(cp); 861 862 if (buffer_get_int(&m)) { 863 if (sensitive_data.server_key != NULL) 864 key_free(sensitive_data.server_key); 865 sensitive_data.server_key = key_new_private(KEY_RSA1); 866 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 867 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 868 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 869 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 870 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 871 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 872 rsa_generate_additional_parameters( 873 sensitive_data.server_key->rsa); 874 } 875 buffer_free(&m); 876 877 debug3("%s: done", __func__); 878 } 879 880 /* Accept a connection from inetd */ 881 static void 882 server_accept_inetd(int *sock_in, int *sock_out) 883 { 884 int fd; 885 886 startup_pipe = -1; 887 if (rexeced_flag) { 888 close(REEXEC_CONFIG_PASS_FD); 889 *sock_in = *sock_out = dup(STDIN_FILENO); 890 if (!debug_flag) { 891 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 892 close(REEXEC_STARTUP_PIPE_FD); 893 } 894 } else { 895 *sock_in = dup(STDIN_FILENO); 896 *sock_out = dup(STDOUT_FILENO); 897 } 898 /* 899 * We intentionally do not close the descriptors 0, 1, and 2 900 * as our code for setting the descriptors won't work if 901 * ttyfd happens to be one of those. 902 */ 903 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 904 dup2(fd, STDIN_FILENO); 905 dup2(fd, STDOUT_FILENO); 906 if (fd > STDOUT_FILENO) 907 close(fd); 908 } 909 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 910 } 911 912 /* 913 * Listen for TCP connections 914 */ 915 static void 916 server_listen(void) 917 { 918 int ret, listen_sock, on = 1; 919 struct addrinfo *ai; 920 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 921 922 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 923 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 924 continue; 925 if (num_listen_socks >= MAX_LISTEN_SOCKS) 926 fatal("Too many listen sockets. " 927 "Enlarge MAX_LISTEN_SOCKS"); 928 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 929 ntop, sizeof(ntop), strport, sizeof(strport), 930 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 931 error("getnameinfo failed: %.100s", 932 ssh_gai_strerror(ret)); 933 continue; 934 } 935 /* Create socket for listening. */ 936 listen_sock = socket(ai->ai_family, ai->ai_socktype, 937 ai->ai_protocol); 938 if (listen_sock < 0) { 939 /* kernel may not support ipv6 */ 940 verbose("socket: %.100s", strerror(errno)); 941 continue; 942 } 943 if (set_nonblock(listen_sock) == -1) { 944 close(listen_sock); 945 continue; 946 } 947 /* 948 * Set socket options. 949 * Allow local port reuse in TIME_WAIT. 950 */ 951 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 952 &on, sizeof(on)) == -1) 953 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 954 955 debug("Bind to port %s on %s.", strport, ntop); 956 957 /* Bind the socket to the desired port. */ 958 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 959 error("Bind to port %s on %s failed: %.200s.", 960 strport, ntop, strerror(errno)); 961 close(listen_sock); 962 continue; 963 } 964 listen_socks[num_listen_socks] = listen_sock; 965 num_listen_socks++; 966 967 /* Start listening on the port. */ 968 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 969 fatal("listen on [%s]:%s: %.100s", 970 ntop, strport, strerror(errno)); 971 logit("Server listening on %s port %s.", ntop, strport); 972 } 973 freeaddrinfo(options.listen_addrs); 974 975 if (!num_listen_socks) 976 fatal("Cannot bind any address."); 977 } 978 979 /* 980 * The main TCP accept loop. Note that, for the non-debug case, returns 981 * from this function are in a forked subprocess. 982 */ 983 static void 984 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 985 { 986 fd_set *fdset; 987 int i, j, ret, maxfd; 988 int key_used = 0, startups = 0; 989 int startup_p[2] = { -1 , -1 }; 990 struct sockaddr_storage from; 991 socklen_t fromlen; 992 pid_t pid; 993 994 /* setup fd set for accept */ 995 fdset = NULL; 996 maxfd = 0; 997 for (i = 0; i < num_listen_socks; i++) 998 if (listen_socks[i] > maxfd) 999 maxfd = listen_socks[i]; 1000 /* pipes connected to unauthenticated childs */ 1001 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1002 for (i = 0; i < options.max_startups; i++) 1003 startup_pipes[i] = -1; 1004 1005 /* 1006 * Stay listening for connections until the system crashes or 1007 * the daemon is killed with a signal. 1008 */ 1009 for (;;) { 1010 if (received_sighup) 1011 sighup_restart(); 1012 if (fdset != NULL) 1013 xfree(fdset); 1014 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1015 sizeof(fd_mask)); 1016 1017 for (i = 0; i < num_listen_socks; i++) 1018 FD_SET(listen_socks[i], fdset); 1019 for (i = 0; i < options.max_startups; i++) 1020 if (startup_pipes[i] != -1) 1021 FD_SET(startup_pipes[i], fdset); 1022 1023 /* Wait in select until there is a connection. */ 1024 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1025 if (ret < 0 && errno != EINTR) 1026 error("select: %.100s", strerror(errno)); 1027 if (received_sigterm) { 1028 logit("Received signal %d; terminating.", 1029 (int) received_sigterm); 1030 close_listen_socks(); 1031 unlink(options.pid_file); 1032 exit(255); 1033 } 1034 if (key_used && key_do_regen) { 1035 generate_ephemeral_server_key(); 1036 key_used = 0; 1037 key_do_regen = 0; 1038 } 1039 if (ret < 0) 1040 continue; 1041 1042 for (i = 0; i < options.max_startups; i++) 1043 if (startup_pipes[i] != -1 && 1044 FD_ISSET(startup_pipes[i], fdset)) { 1045 /* 1046 * the read end of the pipe is ready 1047 * if the child has closed the pipe 1048 * after successful authentication 1049 * or if the child has died 1050 */ 1051 close(startup_pipes[i]); 1052 startup_pipes[i] = -1; 1053 startups--; 1054 } 1055 for (i = 0; i < num_listen_socks; i++) { 1056 if (!FD_ISSET(listen_socks[i], fdset)) 1057 continue; 1058 fromlen = sizeof(from); 1059 *newsock = accept(listen_socks[i], 1060 (struct sockaddr *)&from, &fromlen); 1061 if (*newsock < 0) { 1062 if (errno != EINTR && errno != EWOULDBLOCK) 1063 error("accept: %.100s", strerror(errno)); 1064 continue; 1065 } 1066 if (unset_nonblock(*newsock) == -1) { 1067 close(*newsock); 1068 continue; 1069 } 1070 if (drop_connection(startups) == 1) { 1071 debug("drop connection #%d", startups); 1072 close(*newsock); 1073 continue; 1074 } 1075 if (pipe(startup_p) == -1) { 1076 close(*newsock); 1077 continue; 1078 } 1079 1080 if (rexec_flag && socketpair(AF_UNIX, 1081 SOCK_STREAM, 0, config_s) == -1) { 1082 error("reexec socketpair: %s", 1083 strerror(errno)); 1084 close(*newsock); 1085 close(startup_p[0]); 1086 close(startup_p[1]); 1087 continue; 1088 } 1089 1090 for (j = 0; j < options.max_startups; j++) 1091 if (startup_pipes[j] == -1) { 1092 startup_pipes[j] = startup_p[0]; 1093 if (maxfd < startup_p[0]) 1094 maxfd = startup_p[0]; 1095 startups++; 1096 break; 1097 } 1098 1099 /* 1100 * Got connection. Fork a child to handle it, unless 1101 * we are in debugging mode. 1102 */ 1103 if (debug_flag) { 1104 /* 1105 * In debugging mode. Close the listening 1106 * socket, and start processing the 1107 * connection without forking. 1108 */ 1109 debug("Server will not fork when running in debugging mode."); 1110 close_listen_socks(); 1111 *sock_in = *newsock; 1112 *sock_out = *newsock; 1113 close(startup_p[0]); 1114 close(startup_p[1]); 1115 startup_pipe = -1; 1116 pid = getpid(); 1117 if (rexec_flag) { 1118 send_rexec_state(config_s[0], 1119 &cfg); 1120 close(config_s[0]); 1121 } 1122 break; 1123 } 1124 1125 /* 1126 * Normal production daemon. Fork, and have 1127 * the child process the connection. The 1128 * parent continues listening. 1129 */ 1130 if ((pid = fork()) == 0) { 1131 /* 1132 * Child. Close the listening and 1133 * max_startup sockets. Start using 1134 * the accepted socket. Reinitialize 1135 * logging (since our pid has changed). 1136 * We break out of the loop to handle 1137 * the connection. 1138 */ 1139 startup_pipe = startup_p[1]; 1140 close_startup_pipes(); 1141 close_listen_socks(); 1142 *sock_in = *newsock; 1143 *sock_out = *newsock; 1144 log_init(__progname, 1145 options.log_level, 1146 options.log_facility, 1147 log_stderr); 1148 if (rexec_flag) 1149 close(config_s[0]); 1150 break; 1151 } 1152 1153 /* Parent. Stay in the loop. */ 1154 if (pid < 0) 1155 error("fork: %.100s", strerror(errno)); 1156 else 1157 debug("Forked child %ld.", (long)pid); 1158 1159 close(startup_p[1]); 1160 1161 if (rexec_flag) { 1162 send_rexec_state(config_s[0], &cfg); 1163 close(config_s[0]); 1164 close(config_s[1]); 1165 } 1166 1167 /* 1168 * Mark that the key has been used (it 1169 * was "given" to the child). 1170 */ 1171 if ((options.protocol & SSH_PROTO_1) && 1172 key_used == 0) { 1173 /* Schedule server key regeneration alarm. */ 1174 signal(SIGALRM, key_regeneration_alarm); 1175 alarm(options.key_regeneration_time); 1176 key_used = 1; 1177 } 1178 1179 close(*newsock); 1180 1181 /* 1182 * Ensure that our random state differs 1183 * from that of the child 1184 */ 1185 arc4random_stir(); 1186 } 1187 1188 /* child process check (or debug mode) */ 1189 if (num_listen_socks < 0) 1190 break; 1191 } 1192 } 1193 1194 1195 /* 1196 * Main program for the daemon. 1197 */ 1198 int 1199 main(int ac, char **av) 1200 { 1201 extern char *optarg; 1202 extern int optind; 1203 int opt, i, on = 1; 1204 int sock_in = -1, sock_out = -1, newsock = -1; 1205 const char *remote_ip; 1206 char *test_user = NULL, *test_host = NULL, *test_addr = NULL; 1207 int remote_port; 1208 char *line, *p, *cp; 1209 int config_s[2] = { -1 , -1 }; 1210 u_int64_t ibytes, obytes; 1211 mode_t new_umask; 1212 Key *key; 1213 Authctxt *authctxt; 1214 1215 /* Save argv. */ 1216 saved_argv = av; 1217 rexec_argc = ac; 1218 1219 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1220 sanitise_stdfd(); 1221 1222 /* Initialize configuration options to their default values. */ 1223 initialize_server_options(&options); 1224 1225 /* Parse command-line arguments. */ 1226 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) { 1227 switch (opt) { 1228 case '4': 1229 options.address_family = AF_INET; 1230 break; 1231 case '6': 1232 options.address_family = AF_INET6; 1233 break; 1234 case 'f': 1235 config_file_name = optarg; 1236 break; 1237 case 'd': 1238 if (debug_flag == 0) { 1239 debug_flag = 1; 1240 options.log_level = SYSLOG_LEVEL_DEBUG1; 1241 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1242 options.log_level++; 1243 break; 1244 case 'D': 1245 no_daemon_flag = 1; 1246 break; 1247 case 'e': 1248 log_stderr = 1; 1249 break; 1250 case 'i': 1251 inetd_flag = 1; 1252 break; 1253 case 'r': 1254 rexec_flag = 0; 1255 break; 1256 case 'R': 1257 rexeced_flag = 1; 1258 inetd_flag = 1; 1259 break; 1260 case 'Q': 1261 /* ignored */ 1262 break; 1263 case 'q': 1264 options.log_level = SYSLOG_LEVEL_QUIET; 1265 break; 1266 case 'b': 1267 options.server_key_bits = (int)strtonum(optarg, 256, 1268 32768, NULL); 1269 break; 1270 case 'p': 1271 options.ports_from_cmdline = 1; 1272 if (options.num_ports >= MAX_PORTS) { 1273 fprintf(stderr, "too many ports.\n"); 1274 exit(1); 1275 } 1276 options.ports[options.num_ports++] = a2port(optarg); 1277 if (options.ports[options.num_ports-1] <= 0) { 1278 fprintf(stderr, "Bad port number.\n"); 1279 exit(1); 1280 } 1281 break; 1282 case 'g': 1283 if ((options.login_grace_time = convtime(optarg)) == -1) { 1284 fprintf(stderr, "Invalid login grace time.\n"); 1285 exit(1); 1286 } 1287 break; 1288 case 'k': 1289 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1290 fprintf(stderr, "Invalid key regeneration interval.\n"); 1291 exit(1); 1292 } 1293 break; 1294 case 'h': 1295 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1296 fprintf(stderr, "too many host keys.\n"); 1297 exit(1); 1298 } 1299 options.host_key_files[options.num_host_key_files++] = optarg; 1300 break; 1301 case 't': 1302 test_flag = 1; 1303 break; 1304 case 'T': 1305 test_flag = 2; 1306 break; 1307 case 'C': 1308 cp = optarg; 1309 while ((p = strsep(&cp, ",")) && *p != '\0') { 1310 if (strncmp(p, "addr=", 5) == 0) 1311 test_addr = xstrdup(p + 5); 1312 else if (strncmp(p, "host=", 5) == 0) 1313 test_host = xstrdup(p + 5); 1314 else if (strncmp(p, "user=", 5) == 0) 1315 test_user = xstrdup(p + 5); 1316 else { 1317 fprintf(stderr, "Invalid test " 1318 "mode specification %s\n", p); 1319 exit(1); 1320 } 1321 } 1322 break; 1323 case 'u': 1324 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1325 if (utmp_len > MAXHOSTNAMELEN) { 1326 fprintf(stderr, "Invalid utmp length.\n"); 1327 exit(1); 1328 } 1329 break; 1330 case 'o': 1331 line = xstrdup(optarg); 1332 if (process_server_config_line(&options, line, 1333 "command-line", 0, NULL, NULL, NULL, NULL) != 0) 1334 exit(1); 1335 xfree(line); 1336 break; 1337 case '?': 1338 default: 1339 usage(); 1340 break; 1341 } 1342 } 1343 if (rexeced_flag || inetd_flag) 1344 rexec_flag = 0; 1345 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1346 fatal("sshd re-exec requires execution with an absolute path"); 1347 if (rexeced_flag) 1348 closefrom(REEXEC_MIN_FREE_FD); 1349 else 1350 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1351 1352 SSLeay_add_all_algorithms(); 1353 1354 /* 1355 * Force logging to stderr until we have loaded the private host 1356 * key (unless started from inetd) 1357 */ 1358 log_init(__progname, 1359 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1360 SYSLOG_LEVEL_INFO : options.log_level, 1361 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1362 SYSLOG_FACILITY_AUTH : options.log_facility, 1363 log_stderr || !inetd_flag); 1364 1365 sensitive_data.server_key = NULL; 1366 sensitive_data.ssh1_host_key = NULL; 1367 sensitive_data.have_ssh1_key = 0; 1368 sensitive_data.have_ssh2_key = 0; 1369 1370 /* 1371 * If we're doing an extended config test, make sure we have all of 1372 * the parameters we need. If we're not doing an extended test, 1373 * do not silently ignore connection test params. 1374 */ 1375 if (test_flag >= 2 && 1376 (test_user != NULL || test_host != NULL || test_addr != NULL) 1377 && (test_user == NULL || test_host == NULL || test_addr == NULL)) 1378 fatal("user, host and addr are all required when testing " 1379 "Match configs"); 1380 if (test_flag < 2 && (test_user != NULL || test_host != NULL || 1381 test_addr != NULL)) 1382 fatal("Config test connection parameter (-C) provided without " 1383 "test mode (-T)"); 1384 1385 /* Fetch our configuration */ 1386 buffer_init(&cfg); 1387 if (rexeced_flag) 1388 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1389 else 1390 load_server_config(config_file_name, &cfg); 1391 1392 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1393 &cfg, NULL, NULL, NULL); 1394 1395 /* Fill in default values for those options not explicitly set. */ 1396 fill_default_server_options(&options); 1397 1398 /* challenge-response is implemented via keyboard interactive */ 1399 if (options.challenge_response_authentication) 1400 options.kbd_interactive_authentication = 1; 1401 1402 /* set default channel AF */ 1403 channel_set_af(options.address_family); 1404 1405 /* Check that there are no remaining arguments. */ 1406 if (optind < ac) { 1407 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1408 exit(1); 1409 } 1410 1411 debug("sshd version %.100s", SSH_VERSION); 1412 1413 /* load private host keys */ 1414 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1415 sizeof(Key *)); 1416 for (i = 0; i < options.num_host_key_files; i++) 1417 sensitive_data.host_keys[i] = NULL; 1418 1419 for (i = 0; i < options.num_host_key_files; i++) { 1420 key = key_load_private(options.host_key_files[i], "", NULL); 1421 sensitive_data.host_keys[i] = key; 1422 if (key == NULL) { 1423 error("Could not load host key: %s", 1424 options.host_key_files[i]); 1425 sensitive_data.host_keys[i] = NULL; 1426 continue; 1427 } 1428 switch (key->type) { 1429 case KEY_RSA1: 1430 sensitive_data.ssh1_host_key = key; 1431 sensitive_data.have_ssh1_key = 1; 1432 break; 1433 case KEY_RSA: 1434 case KEY_DSA: 1435 sensitive_data.have_ssh2_key = 1; 1436 break; 1437 } 1438 debug("private host key: #%d type %d %s", i, key->type, 1439 key_type(key)); 1440 } 1441 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1442 logit("Disabling protocol version 1. Could not load host key"); 1443 options.protocol &= ~SSH_PROTO_1; 1444 } 1445 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1446 logit("Disabling protocol version 2. Could not load host key"); 1447 options.protocol &= ~SSH_PROTO_2; 1448 } 1449 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1450 logit("sshd: no hostkeys available -- exiting."); 1451 exit(1); 1452 } 1453 1454 /* Check certain values for sanity. */ 1455 if (options.protocol & SSH_PROTO_1) { 1456 if (options.server_key_bits < 512 || 1457 options.server_key_bits > 32768) { 1458 fprintf(stderr, "Bad server key size.\n"); 1459 exit(1); 1460 } 1461 /* 1462 * Check that server and host key lengths differ sufficiently. This 1463 * is necessary to make double encryption work with rsaref. Oh, I 1464 * hate software patents. I dont know if this can go? Niels 1465 */ 1466 if (options.server_key_bits > 1467 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1468 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1469 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1470 SSH_KEY_BITS_RESERVED) { 1471 options.server_key_bits = 1472 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1473 SSH_KEY_BITS_RESERVED; 1474 debug("Forcing server key to %d bits to make it differ from host key.", 1475 options.server_key_bits); 1476 } 1477 } 1478 1479 if (use_privsep) { 1480 struct stat st; 1481 1482 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1483 fatal("Privilege separation user %s does not exist", 1484 SSH_PRIVSEP_USER); 1485 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1486 (S_ISDIR(st.st_mode) == 0)) 1487 fatal("Missing privilege separation directory: %s", 1488 _PATH_PRIVSEP_CHROOT_DIR); 1489 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1490 fatal("%s must be owned by root and not group or " 1491 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1492 } 1493 1494 if (test_flag > 1) { 1495 if (test_user != NULL && test_addr != NULL && test_host != NULL) 1496 parse_server_match_config(&options, test_user, 1497 test_host, test_addr); 1498 dump_config(&options); 1499 } 1500 1501 /* Configuration looks good, so exit if in test mode. */ 1502 if (test_flag) 1503 exit(0); 1504 1505 if (rexec_flag) { 1506 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1507 for (i = 0; i < rexec_argc; i++) { 1508 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1509 rexec_argv[i] = saved_argv[i]; 1510 } 1511 rexec_argv[rexec_argc] = "-R"; 1512 rexec_argv[rexec_argc + 1] = NULL; 1513 } 1514 1515 /* Ensure that umask disallows at least group and world write */ 1516 new_umask = umask(0077) | 0022; 1517 (void) umask(new_umask); 1518 1519 /* Initialize the log (it is reinitialized below in case we forked). */ 1520 if (debug_flag && (!inetd_flag || rexeced_flag)) 1521 log_stderr = 1; 1522 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1523 1524 /* 1525 * If not in debugging mode, and not started from inetd, disconnect 1526 * from the controlling terminal, and fork. The original process 1527 * exits. 1528 */ 1529 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1530 int fd; 1531 1532 if (daemon(0, 0) < 0) 1533 fatal("daemon() failed: %.200s", strerror(errno)); 1534 1535 /* Disconnect from the controlling tty. */ 1536 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1537 if (fd >= 0) { 1538 (void) ioctl(fd, TIOCNOTTY, NULL); 1539 close(fd); 1540 } 1541 } 1542 /* Reinitialize the log (because of the fork above). */ 1543 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1544 1545 /* Initialize the random number generator. */ 1546 arc4random_stir(); 1547 1548 /* Chdir to the root directory so that the current disk can be 1549 unmounted if desired. */ 1550 chdir("/"); 1551 1552 /* ignore SIGPIPE */ 1553 signal(SIGPIPE, SIG_IGN); 1554 1555 /* Get a connection, either from inetd or a listening TCP socket */ 1556 if (inetd_flag) { 1557 server_accept_inetd(&sock_in, &sock_out); 1558 } else { 1559 server_listen(); 1560 1561 if (options.protocol & SSH_PROTO_1) 1562 generate_ephemeral_server_key(); 1563 1564 signal(SIGHUP, sighup_handler); 1565 signal(SIGCHLD, main_sigchld_handler); 1566 signal(SIGTERM, sigterm_handler); 1567 signal(SIGQUIT, sigterm_handler); 1568 1569 /* 1570 * Write out the pid file after the sigterm handler 1571 * is setup and the listen sockets are bound 1572 */ 1573 if (!debug_flag) { 1574 FILE *f = fopen(options.pid_file, "w"); 1575 1576 if (f == NULL) { 1577 error("Couldn't create pid file \"%s\": %s", 1578 options.pid_file, strerror(errno)); 1579 } else { 1580 fprintf(f, "%ld\n", (long) getpid()); 1581 fclose(f); 1582 } 1583 } 1584 1585 /* Accept a connection and return in a forked child */ 1586 server_accept_loop(&sock_in, &sock_out, 1587 &newsock, config_s); 1588 } 1589 1590 /* This is the child processing a new connection. */ 1591 setproctitle("%s", "[accepted]"); 1592 1593 /* 1594 * Create a new session and process group since the 4.4BSD 1595 * setlogin() affects the entire process group. We don't 1596 * want the child to be able to affect the parent. 1597 */ 1598 if (!debug_flag && !inetd_flag && setsid() < 0) 1599 error("setsid: %.100s", strerror(errno)); 1600 1601 if (rexec_flag) { 1602 int fd; 1603 1604 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1605 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1606 dup2(newsock, STDIN_FILENO); 1607 dup2(STDIN_FILENO, STDOUT_FILENO); 1608 if (startup_pipe == -1) 1609 close(REEXEC_STARTUP_PIPE_FD); 1610 else 1611 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1612 1613 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1614 close(config_s[1]); 1615 if (startup_pipe != -1) 1616 close(startup_pipe); 1617 1618 execv(rexec_argv[0], rexec_argv); 1619 1620 /* Reexec has failed, fall back and continue */ 1621 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1622 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1623 log_init(__progname, options.log_level, 1624 options.log_facility, log_stderr); 1625 1626 /* Clean up fds */ 1627 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1628 close(config_s[1]); 1629 close(REEXEC_CONFIG_PASS_FD); 1630 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1631 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1632 dup2(fd, STDIN_FILENO); 1633 dup2(fd, STDOUT_FILENO); 1634 if (fd > STDERR_FILENO) 1635 close(fd); 1636 } 1637 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1638 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1639 } 1640 1641 /* 1642 * Disable the key regeneration alarm. We will not regenerate the 1643 * key since we are no longer in a position to give it to anyone. We 1644 * will not restart on SIGHUP since it no longer makes sense. 1645 */ 1646 alarm(0); 1647 signal(SIGALRM, SIG_DFL); 1648 signal(SIGHUP, SIG_DFL); 1649 signal(SIGTERM, SIG_DFL); 1650 signal(SIGQUIT, SIG_DFL); 1651 signal(SIGCHLD, SIG_DFL); 1652 1653 /* 1654 * Register our connection. This turns encryption off because we do 1655 * not have a key. 1656 */ 1657 packet_set_connection(sock_in, sock_out); 1658 packet_set_server(); 1659 1660 /* Set SO_KEEPALIVE if requested. */ 1661 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1662 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1663 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1664 1665 if ((remote_port = get_remote_port()) < 0) { 1666 debug("get_remote_port failed"); 1667 cleanup_exit(255); 1668 } 1669 1670 /* 1671 * We use get_canonical_hostname with usedns = 0 instead of 1672 * get_remote_ipaddr here so IP options will be checked. 1673 */ 1674 (void) get_canonical_hostname(0); 1675 /* 1676 * The rest of the code depends on the fact that 1677 * get_remote_ipaddr() caches the remote ip, even if 1678 * the socket goes away. 1679 */ 1680 remote_ip = get_remote_ipaddr(); 1681 1682 #ifdef LIBWRAP 1683 /* Check whether logins are denied from this host. */ 1684 if (packet_connection_is_on_socket()) { 1685 struct request_info req; 1686 1687 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 1688 fromhost(&req); 1689 1690 if (!hosts_access(&req)) { 1691 debug("Connection refused by tcp wrapper"); 1692 refuse(&req); 1693 /* NOTREACHED */ 1694 fatal("libwrap refuse returns"); 1695 } 1696 } 1697 #endif /* LIBWRAP */ 1698 1699 /* Log the connection. */ 1700 verbose("Connection from %.500s port %d", remote_ip, remote_port); 1701 1702 /* 1703 * We don't want to listen forever unless the other side 1704 * successfully authenticates itself. So we set up an alarm which is 1705 * cleared after successful authentication. A limit of zero 1706 * indicates no limit. Note that we don't set the alarm in debugging 1707 * mode; it is just annoying to have the server exit just when you 1708 * are about to discover the bug. 1709 */ 1710 signal(SIGALRM, grace_alarm_handler); 1711 if (!debug_flag) 1712 alarm(options.login_grace_time); 1713 1714 sshd_exchange_identification(sock_in, sock_out); 1715 1716 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 1717 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 1718 generate_ephemeral_server_key(); 1719 1720 packet_set_nonblocking(); 1721 1722 /* allocate authentication context */ 1723 authctxt = xcalloc(1, sizeof(*authctxt)); 1724 1725 /* XXX global for cleanup, access from other modules */ 1726 the_authctxt = authctxt; 1727 1728 /* prepare buffer to collect messages to display to user after login */ 1729 buffer_init(&loginmsg); 1730 1731 if (use_privsep) 1732 if (privsep_preauth(authctxt) == 1) 1733 goto authenticated; 1734 1735 /* perform the key exchange */ 1736 /* authenticate user and start session */ 1737 if (compat20) { 1738 do_ssh2_kex(); 1739 do_authentication2(authctxt); 1740 } else { 1741 do_ssh1_kex(); 1742 do_authentication(authctxt); 1743 } 1744 /* 1745 * If we use privilege separation, the unprivileged child transfers 1746 * the current keystate and exits 1747 */ 1748 if (use_privsep) { 1749 mm_send_keystate(pmonitor); 1750 exit(0); 1751 } 1752 1753 authenticated: 1754 /* 1755 * Cancel the alarm we set to limit the time taken for 1756 * authentication. 1757 */ 1758 alarm(0); 1759 signal(SIGALRM, SIG_DFL); 1760 authctxt->authenticated = 1; 1761 if (startup_pipe != -1) { 1762 close(startup_pipe); 1763 startup_pipe = -1; 1764 } 1765 1766 /* 1767 * In privilege separation, we fork another child and prepare 1768 * file descriptor passing. 1769 */ 1770 if (use_privsep) { 1771 privsep_postauth(authctxt); 1772 /* the monitor process [priv] will not return */ 1773 if (!compat20) 1774 destroy_sensitive_data(); 1775 } 1776 1777 packet_set_timeout(options.client_alive_interval, 1778 options.client_alive_count_max); 1779 1780 /* Start session. */ 1781 do_authenticated(authctxt); 1782 1783 /* The connection has been terminated. */ 1784 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 1785 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 1786 verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes); 1787 1788 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 1789 packet_close(); 1790 1791 if (use_privsep) 1792 mm_terminate(); 1793 1794 exit(0); 1795 } 1796 1797 /* 1798 * Decrypt session_key_int using our private server key and private host key 1799 * (key with larger modulus first). 1800 */ 1801 int 1802 ssh1_session_key(BIGNUM *session_key_int) 1803 { 1804 int rsafail = 0; 1805 1806 if (BN_cmp(sensitive_data.server_key->rsa->n, 1807 sensitive_data.ssh1_host_key->rsa->n) > 0) { 1808 /* Server key has bigger modulus. */ 1809 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 1810 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1811 SSH_KEY_BITS_RESERVED) { 1812 fatal("do_connection: %s: " 1813 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 1814 get_remote_ipaddr(), 1815 BN_num_bits(sensitive_data.server_key->rsa->n), 1816 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 1817 SSH_KEY_BITS_RESERVED); 1818 } 1819 if (rsa_private_decrypt(session_key_int, session_key_int, 1820 sensitive_data.server_key->rsa) <= 0) 1821 rsafail++; 1822 if (rsa_private_decrypt(session_key_int, session_key_int, 1823 sensitive_data.ssh1_host_key->rsa) <= 0) 1824 rsafail++; 1825 } else { 1826 /* Host key has bigger modulus (or they are equal). */ 1827 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 1828 BN_num_bits(sensitive_data.server_key->rsa->n) + 1829 SSH_KEY_BITS_RESERVED) { 1830 fatal("do_connection: %s: " 1831 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 1832 get_remote_ipaddr(), 1833 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 1834 BN_num_bits(sensitive_data.server_key->rsa->n), 1835 SSH_KEY_BITS_RESERVED); 1836 } 1837 if (rsa_private_decrypt(session_key_int, session_key_int, 1838 sensitive_data.ssh1_host_key->rsa) < 0) 1839 rsafail++; 1840 if (rsa_private_decrypt(session_key_int, session_key_int, 1841 sensitive_data.server_key->rsa) < 0) 1842 rsafail++; 1843 } 1844 return (rsafail); 1845 } 1846 /* 1847 * SSH1 key exchange 1848 */ 1849 static void 1850 do_ssh1_kex(void) 1851 { 1852 int i, len; 1853 int rsafail = 0; 1854 BIGNUM *session_key_int; 1855 u_char session_key[SSH_SESSION_KEY_LENGTH]; 1856 u_char cookie[8]; 1857 u_int cipher_type, auth_mask, protocol_flags; 1858 1859 /* 1860 * Generate check bytes that the client must send back in the user 1861 * packet in order for it to be accepted; this is used to defy ip 1862 * spoofing attacks. Note that this only works against somebody 1863 * doing IP spoofing from a remote machine; any machine on the local 1864 * network can still see outgoing packets and catch the random 1865 * cookie. This only affects rhosts authentication, and this is one 1866 * of the reasons why it is inherently insecure. 1867 */ 1868 arc4random_buf(cookie, sizeof(cookie)); 1869 1870 /* 1871 * Send our public key. We include in the packet 64 bits of random 1872 * data that must be matched in the reply in order to prevent IP 1873 * spoofing. 1874 */ 1875 packet_start(SSH_SMSG_PUBLIC_KEY); 1876 for (i = 0; i < 8; i++) 1877 packet_put_char(cookie[i]); 1878 1879 /* Store our public server RSA key. */ 1880 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 1881 packet_put_bignum(sensitive_data.server_key->rsa->e); 1882 packet_put_bignum(sensitive_data.server_key->rsa->n); 1883 1884 /* Store our public host RSA key. */ 1885 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 1886 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 1887 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 1888 1889 /* Put protocol flags. */ 1890 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 1891 1892 /* Declare which ciphers we support. */ 1893 packet_put_int(cipher_mask_ssh1(0)); 1894 1895 /* Declare supported authentication types. */ 1896 auth_mask = 0; 1897 if (options.rhosts_rsa_authentication) 1898 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 1899 if (options.rsa_authentication) 1900 auth_mask |= 1 << SSH_AUTH_RSA; 1901 if (options.challenge_response_authentication == 1) 1902 auth_mask |= 1 << SSH_AUTH_TIS; 1903 if (options.password_authentication) 1904 auth_mask |= 1 << SSH_AUTH_PASSWORD; 1905 packet_put_int(auth_mask); 1906 1907 /* Send the packet and wait for it to be sent. */ 1908 packet_send(); 1909 packet_write_wait(); 1910 1911 debug("Sent %d bit server key and %d bit host key.", 1912 BN_num_bits(sensitive_data.server_key->rsa->n), 1913 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 1914 1915 /* Read clients reply (cipher type and session key). */ 1916 packet_read_expect(SSH_CMSG_SESSION_KEY); 1917 1918 /* Get cipher type and check whether we accept this. */ 1919 cipher_type = packet_get_char(); 1920 1921 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 1922 packet_disconnect("Warning: client selects unsupported cipher."); 1923 1924 /* Get check bytes from the packet. These must match those we 1925 sent earlier with the public key packet. */ 1926 for (i = 0; i < 8; i++) 1927 if (cookie[i] != packet_get_char()) 1928 packet_disconnect("IP Spoofing check bytes do not match."); 1929 1930 debug("Encryption type: %.200s", cipher_name(cipher_type)); 1931 1932 /* Get the encrypted integer. */ 1933 if ((session_key_int = BN_new()) == NULL) 1934 fatal("do_ssh1_kex: BN_new failed"); 1935 packet_get_bignum(session_key_int); 1936 1937 protocol_flags = packet_get_int(); 1938 packet_set_protocol_flags(protocol_flags); 1939 packet_check_eom(); 1940 1941 /* Decrypt session_key_int using host/server keys */ 1942 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 1943 1944 /* 1945 * Extract session key from the decrypted integer. The key is in the 1946 * least significant 256 bits of the integer; the first byte of the 1947 * key is in the highest bits. 1948 */ 1949 if (!rsafail) { 1950 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 1951 len = BN_num_bytes(session_key_int); 1952 if (len < 0 || (u_int)len > sizeof(session_key)) { 1953 error("do_ssh1_kex: bad session key len from %s: " 1954 "session_key_int %d > sizeof(session_key) %lu", 1955 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 1956 rsafail++; 1957 } else { 1958 memset(session_key, 0, sizeof(session_key)); 1959 BN_bn2bin(session_key_int, 1960 session_key + sizeof(session_key) - len); 1961 1962 derive_ssh1_session_id( 1963 sensitive_data.ssh1_host_key->rsa->n, 1964 sensitive_data.server_key->rsa->n, 1965 cookie, session_id); 1966 /* 1967 * Xor the first 16 bytes of the session key with the 1968 * session id. 1969 */ 1970 for (i = 0; i < 16; i++) 1971 session_key[i] ^= session_id[i]; 1972 } 1973 } 1974 if (rsafail) { 1975 int bytes = BN_num_bytes(session_key_int); 1976 u_char *buf = xmalloc(bytes); 1977 MD5_CTX md; 1978 1979 logit("do_connection: generating a fake encryption key"); 1980 BN_bn2bin(session_key_int, buf); 1981 MD5_Init(&md); 1982 MD5_Update(&md, buf, bytes); 1983 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 1984 MD5_Final(session_key, &md); 1985 MD5_Init(&md); 1986 MD5_Update(&md, session_key, 16); 1987 MD5_Update(&md, buf, bytes); 1988 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 1989 MD5_Final(session_key + 16, &md); 1990 memset(buf, 0, bytes); 1991 xfree(buf); 1992 for (i = 0; i < 16; i++) 1993 session_id[i] = session_key[i] ^ session_key[i + 16]; 1994 } 1995 /* Destroy the private and public keys. No longer. */ 1996 destroy_sensitive_data(); 1997 1998 if (use_privsep) 1999 mm_ssh1_session_id(session_id); 2000 2001 /* Destroy the decrypted integer. It is no longer needed. */ 2002 BN_clear_free(session_key_int); 2003 2004 /* Set the session key. From this on all communications will be encrypted. */ 2005 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2006 2007 /* Destroy our copy of the session key. It is no longer needed. */ 2008 memset(session_key, 0, sizeof(session_key)); 2009 2010 debug("Received session key; encryption turned on."); 2011 2012 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2013 packet_start(SSH_SMSG_SUCCESS); 2014 packet_send(); 2015 packet_write_wait(); 2016 } 2017 2018 /* 2019 * SSH2 key exchange: diffie-hellman-group1-sha1 2020 */ 2021 static void 2022 do_ssh2_kex(void) 2023 { 2024 Kex *kex; 2025 2026 if (options.ciphers != NULL) { 2027 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2028 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2029 } 2030 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2031 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2032 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2033 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2034 2035 if (options.macs != NULL) { 2036 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2037 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2038 } 2039 if (options.compression == COMP_NONE) { 2040 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2041 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2042 } else if (options.compression == COMP_DELAYED) { 2043 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2044 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2045 } 2046 2047 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); 2048 2049 /* start key exchange */ 2050 kex = kex_setup(myproposal); 2051 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2052 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2053 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2054 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2055 kex->server = 1; 2056 kex->client_version_string=client_version_string; 2057 kex->server_version_string=server_version_string; 2058 kex->load_host_key=&get_hostkey_by_type; 2059 kex->host_key_index=&get_hostkey_index; 2060 2061 xxx_kex = kex; 2062 2063 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2064 2065 session_id2 = kex->session_id; 2066 session_id2_len = kex->session_id_len; 2067 2068 #ifdef DEBUG_KEXDH 2069 /* send 1st encrypted/maced/compressed message */ 2070 packet_start(SSH2_MSG_IGNORE); 2071 packet_put_cstring("markus"); 2072 packet_send(); 2073 packet_write_wait(); 2074 #endif 2075 debug("KEX done"); 2076 } 2077 2078 /* server specific fatal cleanup */ 2079 void 2080 cleanup_exit(int i) 2081 { 2082 if (the_authctxt) 2083 do_cleanup(the_authctxt); 2084 _exit(i); 2085 } 2086