1 /* $OpenBSD: sshd.c,v 1.347 2006/08/18 09:15:20 markus Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This program is the ssh daemon. It listens for connections from clients, 7 * and performs authentication, executes use commands or shell, and forwards 8 * information to/from the application to the user client over an encrypted 9 * connection. This can also handle forwarding of X11, TCP/IP, and 10 * authentication agent connections. 11 * 12 * As far as I am concerned, the code I have written for this software 13 * can be used freely for any purpose. Any derived versions of this 14 * software must be clearly marked as such, and if the derived work is 15 * incompatible with the protocol description in the RFC file, it must be 16 * called by a name other than "ssh" or "Secure Shell". 17 * 18 * SSH2 implementation: 19 * Privilege Separation: 20 * 21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 22 * Copyright (c) 2002 Niels Provos. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 43 */ 44 45 #include "includes.h" 46 __RCSID("$FreeBSD$"); 47 48 #include <sys/types.h> 49 #include <sys/ioctl.h> 50 #include <sys/socket.h> 51 #ifdef HAVE_SYS_STAT_H 52 # include <sys/stat.h> 53 #endif 54 #ifdef HAVE_SYS_TIME_H 55 # include <sys/time.h> 56 #endif 57 #include "openbsd-compat/sys-tree.h" 58 #include <sys/wait.h> 59 60 #include <errno.h> 61 #include <fcntl.h> 62 #include <netdb.h> 63 #ifdef HAVE_PATHS_H 64 #include <paths.h> 65 #endif 66 #include <grp.h> 67 #include <pwd.h> 68 #include <signal.h> 69 #include <stdarg.h> 70 #include <stdio.h> 71 #include <stdlib.h> 72 #include <string.h> 73 #include <unistd.h> 74 75 #include <openssl/dh.h> 76 #include <openssl/bn.h> 77 #include <openssl/md5.h> 78 #include <openssl/rand.h> 79 #ifdef HAVE_SECUREWARE 80 #include <sys/security.h> 81 #include <prot.h> 82 #endif 83 84 #ifdef __FreeBSD__ 85 #include <resolv.h> 86 #if defined(GSSAPI) && defined(HAVE_GSSAPI_H) 87 #include <gssapi.h> 88 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H) 89 #include <gssapi/gssapi.h> 90 #endif 91 #endif 92 93 #include "xmalloc.h" 94 #include "ssh.h" 95 #include "ssh1.h" 96 #include "ssh2.h" 97 #include "rsa.h" 98 #include "sshpty.h" 99 #include "packet.h" 100 #include "log.h" 101 #include "buffer.h" 102 #include "servconf.h" 103 #include "uidswap.h" 104 #include "compat.h" 105 #include "cipher.h" 106 #include "key.h" 107 #include "kex.h" 108 #include "dh.h" 109 #include "myproposal.h" 110 #include "authfile.h" 111 #include "pathnames.h" 112 #include "atomicio.h" 113 #include "canohost.h" 114 #include "hostfile.h" 115 #include "auth.h" 116 #include "misc.h" 117 #include "msg.h" 118 #include "dispatch.h" 119 #include "channels.h" 120 #include "session.h" 121 #include "monitor_mm.h" 122 #include "monitor.h" 123 #ifdef GSSAPI 124 #include "ssh-gss.h" 125 #endif 126 #include "monitor_wrap.h" 127 #include "monitor_fdpass.h" 128 #include "version.h" 129 130 #ifdef LIBWRAP 131 #include <tcpd.h> 132 #include <syslog.h> 133 int allow_severity = LOG_INFO; 134 int deny_severity = LOG_WARNING; 135 #endif /* LIBWRAP */ 136 137 #ifndef O_NOCTTY 138 #define O_NOCTTY 0 139 #endif 140 141 /* Re-exec fds */ 142 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 143 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 144 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 145 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 146 147 extern char *__progname; 148 149 /* Server configuration options. */ 150 ServerOptions options; 151 152 /* Name of the server configuration file. */ 153 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 154 155 /* 156 * Debug mode flag. This can be set on the command line. If debug 157 * mode is enabled, extra debugging output will be sent to the system 158 * log, the daemon will not go to background, and will exit after processing 159 * the first connection. 160 */ 161 int debug_flag = 0; 162 163 /* Flag indicating that the daemon should only test the configuration and keys. */ 164 int test_flag = 0; 165 166 /* Flag indicating that the daemon is being started from inetd. */ 167 int inetd_flag = 0; 168 169 /* Flag indicating that sshd should not detach and become a daemon. */ 170 int no_daemon_flag = 0; 171 172 /* debug goes to stderr unless inetd_flag is set */ 173 int log_stderr = 0; 174 175 /* Saved arguments to main(). */ 176 char **saved_argv; 177 int saved_argc; 178 179 /* re-exec */ 180 int rexeced_flag = 0; 181 int rexec_flag = 1; 182 int rexec_argc = 0; 183 char **rexec_argv; 184 185 /* 186 * The sockets that the server is listening; this is used in the SIGHUP 187 * signal handler. 188 */ 189 #define MAX_LISTEN_SOCKS 16 190 int listen_socks[MAX_LISTEN_SOCKS]; 191 int num_listen_socks = 0; 192 193 /* 194 * the client's version string, passed by sshd2 in compat mode. if != NULL, 195 * sshd will skip the version-number exchange 196 */ 197 char *client_version_string = NULL; 198 char *server_version_string = NULL; 199 200 /* for rekeying XXX fixme */ 201 Kex *xxx_kex; 202 203 /* 204 * Any really sensitive data in the application is contained in this 205 * structure. The idea is that this structure could be locked into memory so 206 * that the pages do not get written into swap. However, there are some 207 * problems. The private key contains BIGNUMs, and we do not (in principle) 208 * have access to the internals of them, and locking just the structure is 209 * not very useful. Currently, memory locking is not implemented. 210 */ 211 struct { 212 Key *server_key; /* ephemeral server key */ 213 Key *ssh1_host_key; /* ssh1 host key */ 214 Key **host_keys; /* all private host keys */ 215 int have_ssh1_key; 216 int have_ssh2_key; 217 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 218 } sensitive_data; 219 220 /* 221 * Flag indicating whether the RSA server key needs to be regenerated. 222 * Is set in the SIGALRM handler and cleared when the key is regenerated. 223 */ 224 static volatile sig_atomic_t key_do_regen = 0; 225 226 /* This is set to true when a signal is received. */ 227 static volatile sig_atomic_t received_sighup = 0; 228 static volatile sig_atomic_t received_sigterm = 0; 229 230 /* session identifier, used by RSA-auth */ 231 u_char session_id[16]; 232 233 /* same for ssh2 */ 234 u_char *session_id2 = NULL; 235 u_int session_id2_len = 0; 236 237 /* record remote hostname or ip */ 238 u_int utmp_len = MAXHOSTNAMELEN; 239 240 /* options.max_startup sized array of fd ints */ 241 int *startup_pipes = NULL; 242 int startup_pipe; /* in child */ 243 244 /* variables used for privilege separation */ 245 int use_privsep = -1; 246 struct monitor *pmonitor = NULL; 247 248 /* global authentication context */ 249 Authctxt *the_authctxt = NULL; 250 251 /* sshd_config buffer */ 252 Buffer cfg; 253 254 /* message to be displayed after login */ 255 Buffer loginmsg; 256 257 /* Unprivileged user */ 258 struct passwd *privsep_pw = NULL; 259 260 /* Prototypes for various functions defined later in this file. */ 261 void destroy_sensitive_data(void); 262 void demote_sensitive_data(void); 263 264 static void do_ssh1_kex(void); 265 static void do_ssh2_kex(void); 266 267 /* 268 * Close all listening sockets 269 */ 270 static void 271 close_listen_socks(void) 272 { 273 int i; 274 275 for (i = 0; i < num_listen_socks; i++) 276 close(listen_socks[i]); 277 num_listen_socks = -1; 278 } 279 280 static void 281 close_startup_pipes(void) 282 { 283 int i; 284 285 if (startup_pipes) 286 for (i = 0; i < options.max_startups; i++) 287 if (startup_pipes[i] != -1) 288 close(startup_pipes[i]); 289 } 290 291 /* 292 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 293 * the effect is to reread the configuration file (and to regenerate 294 * the server key). 295 */ 296 297 /*ARGSUSED*/ 298 static void 299 sighup_handler(int sig) 300 { 301 int save_errno = errno; 302 303 received_sighup = 1; 304 signal(SIGHUP, sighup_handler); 305 errno = save_errno; 306 } 307 308 /* 309 * Called from the main program after receiving SIGHUP. 310 * Restarts the server. 311 */ 312 static void 313 sighup_restart(void) 314 { 315 logit("Received SIGHUP; restarting."); 316 close_listen_socks(); 317 close_startup_pipes(); 318 execv(saved_argv[0], saved_argv); 319 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 320 strerror(errno)); 321 exit(1); 322 } 323 324 /* 325 * Generic signal handler for terminating signals in the master daemon. 326 */ 327 /*ARGSUSED*/ 328 static void 329 sigterm_handler(int sig) 330 { 331 received_sigterm = sig; 332 } 333 334 /* 335 * SIGCHLD handler. This is called whenever a child dies. This will then 336 * reap any zombies left by exited children. 337 */ 338 /*ARGSUSED*/ 339 static void 340 main_sigchld_handler(int sig) 341 { 342 int save_errno = errno; 343 pid_t pid; 344 int status; 345 346 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 347 (pid < 0 && errno == EINTR)) 348 ; 349 350 signal(SIGCHLD, main_sigchld_handler); 351 errno = save_errno; 352 } 353 354 /* 355 * Signal handler for the alarm after the login grace period has expired. 356 */ 357 /*ARGSUSED*/ 358 static void 359 grace_alarm_handler(int sig) 360 { 361 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 362 kill(pmonitor->m_pid, SIGALRM); 363 364 /* Log error and exit. */ 365 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 366 } 367 368 /* 369 * Signal handler for the key regeneration alarm. Note that this 370 * alarm only occurs in the daemon waiting for connections, and it does not 371 * do anything with the private key or random state before forking. 372 * Thus there should be no concurrency control/asynchronous execution 373 * problems. 374 */ 375 static void 376 generate_ephemeral_server_key(void) 377 { 378 u_int32_t rnd = 0; 379 int i; 380 381 verbose("Generating %s%d bit RSA key.", 382 sensitive_data.server_key ? "new " : "", options.server_key_bits); 383 if (sensitive_data.server_key != NULL) 384 key_free(sensitive_data.server_key); 385 sensitive_data.server_key = key_generate(KEY_RSA1, 386 options.server_key_bits); 387 verbose("RSA key generation complete."); 388 389 for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { 390 if (i % 4 == 0) 391 rnd = arc4random(); 392 sensitive_data.ssh1_cookie[i] = rnd & 0xff; 393 rnd >>= 8; 394 } 395 arc4random_stir(); 396 } 397 398 /*ARGSUSED*/ 399 static void 400 key_regeneration_alarm(int sig) 401 { 402 int save_errno = errno; 403 404 signal(SIGALRM, SIG_DFL); 405 errno = save_errno; 406 key_do_regen = 1; 407 } 408 409 static void 410 sshd_exchange_identification(int sock_in, int sock_out) 411 { 412 u_int i; 413 int mismatch; 414 int remote_major, remote_minor; 415 int major, minor; 416 char *s; 417 char buf[256]; /* Must not be larger than remote_version. */ 418 char remote_version[256]; /* Must be at least as big as buf. */ 419 420 if ((options.protocol & SSH_PROTO_1) && 421 (options.protocol & SSH_PROTO_2)) { 422 major = PROTOCOL_MAJOR_1; 423 minor = 99; 424 } else if (options.protocol & SSH_PROTO_2) { 425 major = PROTOCOL_MAJOR_2; 426 minor = PROTOCOL_MINOR_2; 427 } else { 428 major = PROTOCOL_MAJOR_1; 429 minor = PROTOCOL_MINOR_1; 430 } 431 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); 432 server_version_string = xstrdup(buf); 433 434 /* Send our protocol version identification. */ 435 if (atomicio(vwrite, sock_out, server_version_string, 436 strlen(server_version_string)) 437 != strlen(server_version_string)) { 438 logit("Could not write ident string to %s", get_remote_ipaddr()); 439 cleanup_exit(255); 440 } 441 442 /* Read other sides version identification. */ 443 memset(buf, 0, sizeof(buf)); 444 for (i = 0; i < sizeof(buf) - 1; i++) { 445 if (atomicio(read, sock_in, &buf[i], 1) != 1) { 446 logit("Did not receive identification string from %s", 447 get_remote_ipaddr()); 448 cleanup_exit(255); 449 } 450 if (buf[i] == '\r') { 451 buf[i] = 0; 452 /* Kludge for F-Secure Macintosh < 1.0.2 */ 453 if (i == 12 && 454 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 455 break; 456 continue; 457 } 458 if (buf[i] == '\n') { 459 buf[i] = 0; 460 break; 461 } 462 } 463 buf[sizeof(buf) - 1] = 0; 464 client_version_string = xstrdup(buf); 465 466 /* 467 * Check that the versions match. In future this might accept 468 * several versions and set appropriate flags to handle them. 469 */ 470 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 471 &remote_major, &remote_minor, remote_version) != 3) { 472 s = "Protocol mismatch.\n"; 473 (void) atomicio(vwrite, sock_out, s, strlen(s)); 474 close(sock_in); 475 close(sock_out); 476 logit("Bad protocol version identification '%.100s' from %s", 477 client_version_string, get_remote_ipaddr()); 478 cleanup_exit(255); 479 } 480 debug("Client protocol version %d.%d; client software version %.100s", 481 remote_major, remote_minor, remote_version); 482 483 compat_datafellows(remote_version); 484 485 if (datafellows & SSH_BUG_PROBE) { 486 logit("probed from %s with %s. Don't panic.", 487 get_remote_ipaddr(), client_version_string); 488 cleanup_exit(255); 489 } 490 491 if (datafellows & SSH_BUG_SCANNER) { 492 logit("scanned from %s with %s. Don't panic.", 493 get_remote_ipaddr(), client_version_string); 494 cleanup_exit(255); 495 } 496 497 mismatch = 0; 498 switch (remote_major) { 499 case 1: 500 if (remote_minor == 99) { 501 if (options.protocol & SSH_PROTO_2) 502 enable_compat20(); 503 else 504 mismatch = 1; 505 break; 506 } 507 if (!(options.protocol & SSH_PROTO_1)) { 508 mismatch = 1; 509 break; 510 } 511 if (remote_minor < 3) { 512 packet_disconnect("Your ssh version is too old and " 513 "is no longer supported. Please install a newer version."); 514 } else if (remote_minor == 3) { 515 /* note that this disables agent-forwarding */ 516 enable_compat13(); 517 } 518 break; 519 case 2: 520 if (options.protocol & SSH_PROTO_2) { 521 enable_compat20(); 522 break; 523 } 524 /* FALLTHROUGH */ 525 default: 526 mismatch = 1; 527 break; 528 } 529 chop(server_version_string); 530 debug("Local version string %.200s", server_version_string); 531 532 if (mismatch) { 533 s = "Protocol major versions differ.\n"; 534 (void) atomicio(vwrite, sock_out, s, strlen(s)); 535 close(sock_in); 536 close(sock_out); 537 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 538 get_remote_ipaddr(), 539 server_version_string, client_version_string); 540 cleanup_exit(255); 541 } 542 } 543 544 /* Destroy the host and server keys. They will no longer be needed. */ 545 void 546 destroy_sensitive_data(void) 547 { 548 int i; 549 550 if (sensitive_data.server_key) { 551 key_free(sensitive_data.server_key); 552 sensitive_data.server_key = NULL; 553 } 554 for (i = 0; i < options.num_host_key_files; i++) { 555 if (sensitive_data.host_keys[i]) { 556 key_free(sensitive_data.host_keys[i]); 557 sensitive_data.host_keys[i] = NULL; 558 } 559 } 560 sensitive_data.ssh1_host_key = NULL; 561 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); 562 } 563 564 /* Demote private to public keys for network child */ 565 void 566 demote_sensitive_data(void) 567 { 568 Key *tmp; 569 int i; 570 571 if (sensitive_data.server_key) { 572 tmp = key_demote(sensitive_data.server_key); 573 key_free(sensitive_data.server_key); 574 sensitive_data.server_key = tmp; 575 } 576 577 for (i = 0; i < options.num_host_key_files; i++) { 578 if (sensitive_data.host_keys[i]) { 579 tmp = key_demote(sensitive_data.host_keys[i]); 580 key_free(sensitive_data.host_keys[i]); 581 sensitive_data.host_keys[i] = tmp; 582 if (tmp->type == KEY_RSA1) 583 sensitive_data.ssh1_host_key = tmp; 584 } 585 } 586 587 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 588 } 589 590 static void 591 privsep_preauth_child(void) 592 { 593 u_int32_t rnd[256]; 594 gid_t gidset[1]; 595 int i; 596 597 /* Enable challenge-response authentication for privilege separation */ 598 privsep_challenge_enable(); 599 600 for (i = 0; i < 256; i++) 601 rnd[i] = arc4random(); 602 RAND_seed(rnd, sizeof(rnd)); 603 604 /* Demote the private keys to public keys. */ 605 demote_sensitive_data(); 606 607 /* Change our root directory */ 608 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 609 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 610 strerror(errno)); 611 if (chdir("/") == -1) 612 fatal("chdir(\"/\"): %s", strerror(errno)); 613 614 /* Drop our privileges */ 615 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 616 (u_int)privsep_pw->pw_gid); 617 #if 0 618 /* XXX not ready, too heavy after chroot */ 619 do_setusercontext(privsep_pw); 620 #else 621 gidset[0] = privsep_pw->pw_gid; 622 if (setgroups(1, gidset) < 0) 623 fatal("setgroups: %.100s", strerror(errno)); 624 permanently_set_uid(privsep_pw); 625 #endif 626 } 627 628 static int 629 privsep_preauth(Authctxt *authctxt) 630 { 631 int status; 632 pid_t pid; 633 634 /* Set up unprivileged child process to deal with network data */ 635 pmonitor = monitor_init(); 636 /* Store a pointer to the kex for later rekeying */ 637 pmonitor->m_pkex = &xxx_kex; 638 639 pid = fork(); 640 if (pid == -1) { 641 fatal("fork of unprivileged child failed"); 642 } else if (pid != 0) { 643 debug2("Network child is on pid %ld", (long)pid); 644 645 close(pmonitor->m_recvfd); 646 pmonitor->m_pid = pid; 647 monitor_child_preauth(authctxt, pmonitor); 648 close(pmonitor->m_sendfd); 649 650 /* Sync memory */ 651 monitor_sync(pmonitor); 652 653 /* Wait for the child's exit status */ 654 while (waitpid(pid, &status, 0) < 0) 655 if (errno != EINTR) 656 break; 657 return (1); 658 } else { 659 /* child */ 660 661 close(pmonitor->m_sendfd); 662 663 /* Demote the child */ 664 if (getuid() == 0 || geteuid() == 0) 665 privsep_preauth_child(); 666 setproctitle("%s", "[net]"); 667 } 668 return (0); 669 } 670 671 static void 672 privsep_postauth(Authctxt *authctxt) 673 { 674 #ifdef DISABLE_FD_PASSING 675 if (1) { 676 #else 677 if (authctxt->pw->pw_uid == 0 || options.use_login) { 678 #endif 679 /* File descriptor passing is broken or root login */ 680 use_privsep = 0; 681 goto skip; 682 } 683 684 /* New socket pair */ 685 monitor_reinit(pmonitor); 686 687 pmonitor->m_pid = fork(); 688 if (pmonitor->m_pid == -1) 689 fatal("fork of unprivileged child failed"); 690 else if (pmonitor->m_pid != 0) { 691 debug2("User child is on pid %ld", (long)pmonitor->m_pid); 692 close(pmonitor->m_recvfd); 693 buffer_clear(&loginmsg); 694 monitor_child_postauth(pmonitor); 695 696 /* NEVERREACHED */ 697 exit(0); 698 } 699 700 close(pmonitor->m_sendfd); 701 702 /* Demote the private keys to public keys. */ 703 demote_sensitive_data(); 704 705 /* Drop privileges */ 706 do_setusercontext(authctxt->pw); 707 708 skip: 709 /* It is safe now to apply the key state */ 710 monitor_apply_keystate(pmonitor); 711 712 /* 713 * Tell the packet layer that authentication was successful, since 714 * this information is not part of the key state. 715 */ 716 packet_set_authenticated(); 717 } 718 719 static char * 720 list_hostkey_types(void) 721 { 722 Buffer b; 723 const char *p; 724 char *ret; 725 int i; 726 727 buffer_init(&b); 728 for (i = 0; i < options.num_host_key_files; i++) { 729 Key *key = sensitive_data.host_keys[i]; 730 if (key == NULL) 731 continue; 732 switch (key->type) { 733 case KEY_RSA: 734 case KEY_DSA: 735 if (buffer_len(&b) > 0) 736 buffer_append(&b, ",", 1); 737 p = key_ssh_name(key); 738 buffer_append(&b, p, strlen(p)); 739 break; 740 } 741 } 742 buffer_append(&b, "\0", 1); 743 ret = xstrdup(buffer_ptr(&b)); 744 buffer_free(&b); 745 debug("list_hostkey_types: %s", ret); 746 return ret; 747 } 748 749 Key * 750 get_hostkey_by_type(int type) 751 { 752 int i; 753 754 for (i = 0; i < options.num_host_key_files; i++) { 755 Key *key = sensitive_data.host_keys[i]; 756 if (key != NULL && key->type == type) 757 return key; 758 } 759 return NULL; 760 } 761 762 Key * 763 get_hostkey_by_index(int ind) 764 { 765 if (ind < 0 || ind >= options.num_host_key_files) 766 return (NULL); 767 return (sensitive_data.host_keys[ind]); 768 } 769 770 int 771 get_hostkey_index(Key *key) 772 { 773 int i; 774 775 for (i = 0; i < options.num_host_key_files; i++) { 776 if (key == sensitive_data.host_keys[i]) 777 return (i); 778 } 779 return (-1); 780 } 781 782 /* 783 * returns 1 if connection should be dropped, 0 otherwise. 784 * dropping starts at connection #max_startups_begin with a probability 785 * of (max_startups_rate/100). the probability increases linearly until 786 * all connections are dropped for startups > max_startups 787 */ 788 static int 789 drop_connection(int startups) 790 { 791 int p, r; 792 793 if (startups < options.max_startups_begin) 794 return 0; 795 if (startups >= options.max_startups) 796 return 1; 797 if (options.max_startups_rate == 100) 798 return 1; 799 800 p = 100 - options.max_startups_rate; 801 p *= startups - options.max_startups_begin; 802 p /= options.max_startups - options.max_startups_begin; 803 p += options.max_startups_rate; 804 r = arc4random() % 100; 805 806 debug("drop_connection: p %d, r %d", p, r); 807 return (r < p) ? 1 : 0; 808 } 809 810 static void 811 usage(void) 812 { 813 fprintf(stderr, "%s, %s\n", 814 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); 815 fprintf(stderr, 816 "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n" 817 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n" 818 ); 819 exit(1); 820 } 821 822 static void 823 send_rexec_state(int fd, Buffer *conf) 824 { 825 Buffer m; 826 827 debug3("%s: entering fd = %d config len %d", __func__, fd, 828 buffer_len(conf)); 829 830 /* 831 * Protocol from reexec master to child: 832 * string configuration 833 * u_int ephemeral_key_follows 834 * bignum e (only if ephemeral_key_follows == 1) 835 * bignum n " 836 * bignum d " 837 * bignum iqmp " 838 * bignum p " 839 * bignum q " 840 * string rngseed (only if OpenSSL is not self-seeded) 841 */ 842 buffer_init(&m); 843 buffer_put_cstring(&m, buffer_ptr(conf)); 844 845 if (sensitive_data.server_key != NULL && 846 sensitive_data.server_key->type == KEY_RSA1) { 847 buffer_put_int(&m, 1); 848 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 849 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 850 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 851 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 852 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 853 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 854 } else 855 buffer_put_int(&m, 0); 856 857 #ifndef OPENSSL_PRNG_ONLY 858 rexec_send_rng_seed(&m); 859 #endif 860 861 if (ssh_msg_send(fd, 0, &m) == -1) 862 fatal("%s: ssh_msg_send failed", __func__); 863 864 buffer_free(&m); 865 866 debug3("%s: done", __func__); 867 } 868 869 static void 870 recv_rexec_state(int fd, Buffer *conf) 871 { 872 Buffer m; 873 char *cp; 874 u_int len; 875 876 debug3("%s: entering fd = %d", __func__, fd); 877 878 buffer_init(&m); 879 880 if (ssh_msg_recv(fd, &m) == -1) 881 fatal("%s: ssh_msg_recv failed", __func__); 882 if (buffer_get_char(&m) != 0) 883 fatal("%s: rexec version mismatch", __func__); 884 885 cp = buffer_get_string(&m, &len); 886 if (conf != NULL) 887 buffer_append(conf, cp, len + 1); 888 xfree(cp); 889 890 if (buffer_get_int(&m)) { 891 if (sensitive_data.server_key != NULL) 892 key_free(sensitive_data.server_key); 893 sensitive_data.server_key = key_new_private(KEY_RSA1); 894 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 895 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 896 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 897 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 898 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 899 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 900 rsa_generate_additional_parameters( 901 sensitive_data.server_key->rsa); 902 } 903 904 #ifndef OPENSSL_PRNG_ONLY 905 rexec_recv_rng_seed(&m); 906 #endif 907 908 buffer_free(&m); 909 910 debug3("%s: done", __func__); 911 } 912 913 /* Accept a connection from inetd */ 914 static void 915 server_accept_inetd(int *sock_in, int *sock_out) 916 { 917 int fd; 918 919 startup_pipe = -1; 920 if (rexeced_flag) { 921 close(REEXEC_CONFIG_PASS_FD); 922 *sock_in = *sock_out = dup(STDIN_FILENO); 923 if (!debug_flag) { 924 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 925 close(REEXEC_STARTUP_PIPE_FD); 926 } 927 } else { 928 *sock_in = dup(STDIN_FILENO); 929 *sock_out = dup(STDOUT_FILENO); 930 } 931 /* 932 * We intentionally do not close the descriptors 0, 1, and 2 933 * as our code for setting the descriptors won't work if 934 * ttyfd happens to be one of those. 935 */ 936 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 937 dup2(fd, STDIN_FILENO); 938 dup2(fd, STDOUT_FILENO); 939 if (fd > STDOUT_FILENO) 940 close(fd); 941 } 942 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 943 } 944 945 /* 946 * Listen for TCP connections 947 */ 948 static void 949 server_listen(void) 950 { 951 int ret, listen_sock, on = 1; 952 struct addrinfo *ai; 953 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 954 955 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 956 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 957 continue; 958 if (num_listen_socks >= MAX_LISTEN_SOCKS) 959 fatal("Too many listen sockets. " 960 "Enlarge MAX_LISTEN_SOCKS"); 961 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 962 ntop, sizeof(ntop), strport, sizeof(strport), 963 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 964 error("getnameinfo failed: %.100s", 965 (ret != EAI_SYSTEM) ? gai_strerror(ret) : 966 strerror(errno)); 967 continue; 968 } 969 /* Create socket for listening. */ 970 listen_sock = socket(ai->ai_family, ai->ai_socktype, 971 ai->ai_protocol); 972 if (listen_sock < 0) { 973 /* kernel may not support ipv6 */ 974 verbose("socket: %.100s", strerror(errno)); 975 continue; 976 } 977 if (set_nonblock(listen_sock) == -1) { 978 close(listen_sock); 979 continue; 980 } 981 /* 982 * Set socket options. 983 * Allow local port reuse in TIME_WAIT. 984 */ 985 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 986 &on, sizeof(on)) == -1) 987 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 988 989 debug("Bind to port %s on %s.", strport, ntop); 990 991 /* Bind the socket to the desired port. */ 992 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 993 error("Bind to port %s on %s failed: %.200s.", 994 strport, ntop, strerror(errno)); 995 close(listen_sock); 996 continue; 997 } 998 listen_socks[num_listen_socks] = listen_sock; 999 num_listen_socks++; 1000 1001 /* Start listening on the port. */ 1002 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1003 fatal("listen on [%s]:%s: %.100s", 1004 ntop, strport, strerror(errno)); 1005 logit("Server listening on %s port %s.", ntop, strport); 1006 } 1007 freeaddrinfo(options.listen_addrs); 1008 1009 if (!num_listen_socks) 1010 fatal("Cannot bind any address."); 1011 } 1012 1013 /* 1014 * The main TCP accept loop. Note that, for the non-debug case, returns 1015 * from this function are in a forked subprocess. 1016 */ 1017 static void 1018 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1019 { 1020 fd_set *fdset; 1021 int i, j, ret, maxfd; 1022 int key_used = 0, startups = 0; 1023 int startup_p[2] = { -1 , -1 }; 1024 struct sockaddr_storage from; 1025 socklen_t fromlen; 1026 pid_t pid; 1027 1028 /* setup fd set for accept */ 1029 fdset = NULL; 1030 maxfd = 0; 1031 for (i = 0; i < num_listen_socks; i++) 1032 if (listen_socks[i] > maxfd) 1033 maxfd = listen_socks[i]; 1034 /* pipes connected to unauthenticated childs */ 1035 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1036 for (i = 0; i < options.max_startups; i++) 1037 startup_pipes[i] = -1; 1038 1039 /* 1040 * Stay listening for connections until the system crashes or 1041 * the daemon is killed with a signal. 1042 */ 1043 for (;;) { 1044 if (received_sighup) 1045 sighup_restart(); 1046 if (fdset != NULL) 1047 xfree(fdset); 1048 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1049 sizeof(fd_mask)); 1050 1051 for (i = 0; i < num_listen_socks; i++) 1052 FD_SET(listen_socks[i], fdset); 1053 for (i = 0; i < options.max_startups; i++) 1054 if (startup_pipes[i] != -1) 1055 FD_SET(startup_pipes[i], fdset); 1056 1057 /* Wait in select until there is a connection. */ 1058 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1059 if (ret < 0 && errno != EINTR) 1060 error("select: %.100s", strerror(errno)); 1061 if (received_sigterm) { 1062 logit("Received signal %d; terminating.", 1063 (int) received_sigterm); 1064 close_listen_socks(); 1065 unlink(options.pid_file); 1066 exit(255); 1067 } 1068 if (key_used && key_do_regen) { 1069 generate_ephemeral_server_key(); 1070 key_used = 0; 1071 key_do_regen = 0; 1072 } 1073 if (ret < 0) 1074 continue; 1075 1076 for (i = 0; i < options.max_startups; i++) 1077 if (startup_pipes[i] != -1 && 1078 FD_ISSET(startup_pipes[i], fdset)) { 1079 /* 1080 * the read end of the pipe is ready 1081 * if the child has closed the pipe 1082 * after successful authentication 1083 * or if the child has died 1084 */ 1085 close(startup_pipes[i]); 1086 startup_pipes[i] = -1; 1087 startups--; 1088 } 1089 for (i = 0; i < num_listen_socks; i++) { 1090 if (!FD_ISSET(listen_socks[i], fdset)) 1091 continue; 1092 fromlen = sizeof(from); 1093 *newsock = accept(listen_socks[i], 1094 (struct sockaddr *)&from, &fromlen); 1095 if (*newsock < 0) { 1096 if (errno != EINTR && errno != EWOULDBLOCK) 1097 error("accept: %.100s", strerror(errno)); 1098 continue; 1099 } 1100 if (unset_nonblock(*newsock) == -1) { 1101 close(*newsock); 1102 continue; 1103 } 1104 if (drop_connection(startups) == 1) { 1105 debug("drop connection #%d", startups); 1106 close(*newsock); 1107 continue; 1108 } 1109 if (pipe(startup_p) == -1) { 1110 close(*newsock); 1111 continue; 1112 } 1113 1114 if (rexec_flag && socketpair(AF_UNIX, 1115 SOCK_STREAM, 0, config_s) == -1) { 1116 error("reexec socketpair: %s", 1117 strerror(errno)); 1118 close(*newsock); 1119 close(startup_p[0]); 1120 close(startup_p[1]); 1121 continue; 1122 } 1123 1124 for (j = 0; j < options.max_startups; j++) 1125 if (startup_pipes[j] == -1) { 1126 startup_pipes[j] = startup_p[0]; 1127 if (maxfd < startup_p[0]) 1128 maxfd = startup_p[0]; 1129 startups++; 1130 break; 1131 } 1132 1133 /* 1134 * Got connection. Fork a child to handle it, unless 1135 * we are in debugging mode. 1136 */ 1137 if (debug_flag) { 1138 /* 1139 * In debugging mode. Close the listening 1140 * socket, and start processing the 1141 * connection without forking. 1142 */ 1143 debug("Server will not fork when running in debugging mode."); 1144 close_listen_socks(); 1145 *sock_in = *newsock; 1146 *sock_out = *newsock; 1147 close(startup_p[0]); 1148 close(startup_p[1]); 1149 startup_pipe = -1; 1150 pid = getpid(); 1151 if (rexec_flag) { 1152 send_rexec_state(config_s[0], 1153 &cfg); 1154 close(config_s[0]); 1155 } 1156 break; 1157 } 1158 1159 /* 1160 * Normal production daemon. Fork, and have 1161 * the child process the connection. The 1162 * parent continues listening. 1163 */ 1164 platform_pre_fork(); 1165 if ((pid = fork()) == 0) { 1166 /* 1167 * Child. Close the listening and 1168 * max_startup sockets. Start using 1169 * the accepted socket. Reinitialize 1170 * logging (since our pid has changed). 1171 * We break out of the loop to handle 1172 * the connection. 1173 */ 1174 platform_post_fork_child(); 1175 startup_pipe = startup_p[1]; 1176 close_startup_pipes(); 1177 close_listen_socks(); 1178 *sock_in = *newsock; 1179 *sock_out = *newsock; 1180 log_init(__progname, 1181 options.log_level, 1182 options.log_facility, 1183 log_stderr); 1184 if (rexec_flag) 1185 close(config_s[0]); 1186 break; 1187 } 1188 1189 /* Parent. Stay in the loop. */ 1190 platform_post_fork_parent(pid); 1191 if (pid < 0) 1192 error("fork: %.100s", strerror(errno)); 1193 else 1194 debug("Forked child %ld.", (long)pid); 1195 1196 close(startup_p[1]); 1197 1198 if (rexec_flag) { 1199 send_rexec_state(config_s[0], &cfg); 1200 close(config_s[0]); 1201 close(config_s[1]); 1202 } 1203 1204 /* 1205 * Mark that the key has been used (it 1206 * was "given" to the child). 1207 */ 1208 if ((options.protocol & SSH_PROTO_1) && 1209 key_used == 0) { 1210 /* Schedule server key regeneration alarm. */ 1211 signal(SIGALRM, key_regeneration_alarm); 1212 alarm(options.key_regeneration_time); 1213 key_used = 1; 1214 } 1215 1216 close(*newsock); 1217 1218 /* 1219 * Ensure that our random state differs 1220 * from that of the child 1221 */ 1222 arc4random_stir(); 1223 } 1224 1225 /* child process check (or debug mode) */ 1226 if (num_listen_socks < 0) 1227 break; 1228 } 1229 } 1230 1231 1232 /* 1233 * Main program for the daemon. 1234 */ 1235 int 1236 main(int ac, char **av) 1237 { 1238 extern char *optarg; 1239 extern int optind; 1240 int opt, i, on = 1; 1241 int sock_in = -1, sock_out = -1, newsock = -1; 1242 const char *remote_ip; 1243 int remote_port; 1244 char *line; 1245 int config_s[2] = { -1 , -1 }; 1246 Key *key; 1247 Authctxt *authctxt; 1248 1249 #ifdef HAVE_SECUREWARE 1250 (void)set_auth_parameters(ac, av); 1251 #endif 1252 __progname = ssh_get_progname(av[0]); 1253 init_rng(); 1254 1255 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1256 saved_argc = ac; 1257 rexec_argc = ac; 1258 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1259 for (i = 0; i < ac; i++) 1260 saved_argv[i] = xstrdup(av[i]); 1261 saved_argv[i] = NULL; 1262 1263 #ifndef HAVE_SETPROCTITLE 1264 /* Prepare for later setproctitle emulation */ 1265 compat_init_setproctitle(ac, av); 1266 av = saved_argv; 1267 #endif 1268 1269 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1270 debug("setgroups(): %.200s", strerror(errno)); 1271 1272 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1273 sanitise_stdfd(); 1274 1275 /* Initialize configuration options to their default values. */ 1276 initialize_server_options(&options); 1277 1278 /* Parse command-line arguments. */ 1279 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) { 1280 switch (opt) { 1281 case '4': 1282 options.address_family = AF_INET; 1283 break; 1284 case '6': 1285 options.address_family = AF_INET6; 1286 break; 1287 case 'f': 1288 config_file_name = optarg; 1289 break; 1290 case 'd': 1291 if (debug_flag == 0) { 1292 debug_flag = 1; 1293 options.log_level = SYSLOG_LEVEL_DEBUG1; 1294 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1295 options.log_level++; 1296 break; 1297 case 'D': 1298 no_daemon_flag = 1; 1299 break; 1300 case 'e': 1301 log_stderr = 1; 1302 break; 1303 case 'i': 1304 inetd_flag = 1; 1305 break; 1306 case 'r': 1307 rexec_flag = 0; 1308 break; 1309 case 'R': 1310 rexeced_flag = 1; 1311 inetd_flag = 1; 1312 break; 1313 case 'Q': 1314 /* ignored */ 1315 break; 1316 case 'q': 1317 options.log_level = SYSLOG_LEVEL_QUIET; 1318 break; 1319 case 'b': 1320 options.server_key_bits = (int)strtonum(optarg, 256, 1321 32768, NULL); 1322 break; 1323 case 'p': 1324 options.ports_from_cmdline = 1; 1325 if (options.num_ports >= MAX_PORTS) { 1326 fprintf(stderr, "too many ports.\n"); 1327 exit(1); 1328 } 1329 options.ports[options.num_ports++] = a2port(optarg); 1330 if (options.ports[options.num_ports-1] == 0) { 1331 fprintf(stderr, "Bad port number.\n"); 1332 exit(1); 1333 } 1334 break; 1335 case 'g': 1336 if ((options.login_grace_time = convtime(optarg)) == -1) { 1337 fprintf(stderr, "Invalid login grace time.\n"); 1338 exit(1); 1339 } 1340 break; 1341 case 'k': 1342 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1343 fprintf(stderr, "Invalid key regeneration interval.\n"); 1344 exit(1); 1345 } 1346 break; 1347 case 'h': 1348 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1349 fprintf(stderr, "too many host keys.\n"); 1350 exit(1); 1351 } 1352 options.host_key_files[options.num_host_key_files++] = optarg; 1353 break; 1354 case 't': 1355 test_flag = 1; 1356 break; 1357 case 'u': 1358 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1359 if (utmp_len > MAXHOSTNAMELEN) { 1360 fprintf(stderr, "Invalid utmp length.\n"); 1361 exit(1); 1362 } 1363 break; 1364 case 'o': 1365 line = xstrdup(optarg); 1366 if (process_server_config_line(&options, line, 1367 "command-line", 0, NULL, NULL, NULL, NULL) != 0) 1368 exit(1); 1369 xfree(line); 1370 break; 1371 case '?': 1372 default: 1373 usage(); 1374 break; 1375 } 1376 } 1377 if (rexeced_flag || inetd_flag) 1378 rexec_flag = 0; 1379 if (rexec_flag && (av[0] == NULL || *av[0] != '/')) 1380 fatal("sshd re-exec requires execution with an absolute path"); 1381 if (rexeced_flag) 1382 closefrom(REEXEC_MIN_FREE_FD); 1383 else 1384 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1385 1386 SSLeay_add_all_algorithms(); 1387 1388 /* 1389 * Force logging to stderr until we have loaded the private host 1390 * key (unless started from inetd) 1391 */ 1392 log_init(__progname, 1393 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1394 SYSLOG_LEVEL_INFO : options.log_level, 1395 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1396 SYSLOG_FACILITY_AUTH : options.log_facility, 1397 log_stderr || !inetd_flag); 1398 1399 /* 1400 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1401 * root's environment 1402 */ 1403 if (getenv("KRB5CCNAME") != NULL) 1404 unsetenv("KRB5CCNAME"); 1405 1406 #ifdef _UNICOS 1407 /* Cray can define user privs drop all privs now! 1408 * Not needed on PRIV_SU systems! 1409 */ 1410 drop_cray_privs(); 1411 #endif 1412 1413 sensitive_data.server_key = NULL; 1414 sensitive_data.ssh1_host_key = NULL; 1415 sensitive_data.have_ssh1_key = 0; 1416 sensitive_data.have_ssh2_key = 0; 1417 1418 /* Fetch our configuration */ 1419 buffer_init(&cfg); 1420 if (rexeced_flag) 1421 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1422 else 1423 load_server_config(config_file_name, &cfg); 1424 1425 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1426 &cfg, NULL, NULL, NULL); 1427 1428 seed_rng(); 1429 1430 /* Fill in default values for those options not explicitly set. */ 1431 fill_default_server_options(&options); 1432 1433 /* set default channel AF */ 1434 channel_set_af(options.address_family); 1435 1436 /* Check that there are no remaining arguments. */ 1437 if (optind < ac) { 1438 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1439 exit(1); 1440 } 1441 1442 debug("sshd version %.100s", SSH_RELEASE); 1443 1444 /* Store privilege separation user for later use */ 1445 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) 1446 fatal("Privilege separation user %s does not exist", 1447 SSH_PRIVSEP_USER); 1448 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd)); 1449 privsep_pw->pw_passwd = "*"; 1450 privsep_pw = pwcopy(privsep_pw); 1451 endpwent(); 1452 1453 /* load private host keys */ 1454 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1455 sizeof(Key *)); 1456 for (i = 0; i < options.num_host_key_files; i++) 1457 sensitive_data.host_keys[i] = NULL; 1458 1459 for (i = 0; i < options.num_host_key_files; i++) { 1460 key = key_load_private(options.host_key_files[i], "", NULL); 1461 sensitive_data.host_keys[i] = key; 1462 if (key == NULL) { 1463 error("Could not load host key: %s", 1464 options.host_key_files[i]); 1465 sensitive_data.host_keys[i] = NULL; 1466 continue; 1467 } 1468 switch (key->type) { 1469 case KEY_RSA1: 1470 sensitive_data.ssh1_host_key = key; 1471 sensitive_data.have_ssh1_key = 1; 1472 break; 1473 case KEY_RSA: 1474 case KEY_DSA: 1475 sensitive_data.have_ssh2_key = 1; 1476 break; 1477 } 1478 debug("private host key: #%d type %d %s", i, key->type, 1479 key_type(key)); 1480 } 1481 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1482 logit("Disabling protocol version 1. Could not load host key"); 1483 options.protocol &= ~SSH_PROTO_1; 1484 } 1485 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1486 logit("Disabling protocol version 2. Could not load host key"); 1487 options.protocol &= ~SSH_PROTO_2; 1488 } 1489 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1490 logit("sshd: no hostkeys available -- exiting."); 1491 exit(1); 1492 } 1493 1494 /* Check certain values for sanity. */ 1495 if (options.protocol & SSH_PROTO_1) { 1496 if (options.server_key_bits < 512 || 1497 options.server_key_bits > 32768) { 1498 fprintf(stderr, "Bad server key size.\n"); 1499 exit(1); 1500 } 1501 /* 1502 * Check that server and host key lengths differ sufficiently. This 1503 * is necessary to make double encryption work with rsaref. Oh, I 1504 * hate software patents. I dont know if this can go? Niels 1505 */ 1506 if (options.server_key_bits > 1507 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1508 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1509 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1510 SSH_KEY_BITS_RESERVED) { 1511 options.server_key_bits = 1512 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1513 SSH_KEY_BITS_RESERVED; 1514 debug("Forcing server key to %d bits to make it differ from host key.", 1515 options.server_key_bits); 1516 } 1517 } 1518 1519 if (use_privsep) { 1520 struct stat st; 1521 1522 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1523 (S_ISDIR(st.st_mode) == 0)) 1524 fatal("Missing privilege separation directory: %s", 1525 _PATH_PRIVSEP_CHROOT_DIR); 1526 1527 #ifdef HAVE_CYGWIN 1528 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1529 (st.st_uid != getuid () || 1530 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1531 #else 1532 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1533 #endif 1534 fatal("%s must be owned by root and not group or " 1535 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1536 } 1537 1538 /* Configuration looks good, so exit if in test mode. */ 1539 if (test_flag) 1540 exit(0); 1541 1542 /* 1543 * Clear out any supplemental groups we may have inherited. This 1544 * prevents inadvertent creation of files with bad modes (in the 1545 * portable version at least, it's certainly possible for PAM 1546 * to create a file, and we can't control the code in every 1547 * module which might be used). 1548 */ 1549 if (setgroups(0, NULL) < 0) 1550 debug("setgroups() failed: %.200s", strerror(errno)); 1551 1552 if (rexec_flag) { 1553 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1554 for (i = 0; i < rexec_argc; i++) { 1555 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1556 rexec_argv[i] = saved_argv[i]; 1557 } 1558 rexec_argv[rexec_argc] = "-R"; 1559 rexec_argv[rexec_argc + 1] = NULL; 1560 } 1561 1562 /* Initialize the log (it is reinitialized below in case we forked). */ 1563 if (debug_flag && (!inetd_flag || rexeced_flag)) 1564 log_stderr = 1; 1565 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1566 1567 /* 1568 * If not in debugging mode, and not started from inetd, disconnect 1569 * from the controlling terminal, and fork. The original process 1570 * exits. 1571 */ 1572 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1573 #ifdef TIOCNOTTY 1574 int fd; 1575 #endif /* TIOCNOTTY */ 1576 if (daemon(0, 0) < 0) 1577 fatal("daemon() failed: %.200s", strerror(errno)); 1578 1579 /* Disconnect from the controlling tty. */ 1580 #ifdef TIOCNOTTY 1581 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1582 if (fd >= 0) { 1583 (void) ioctl(fd, TIOCNOTTY, NULL); 1584 close(fd); 1585 } 1586 #endif /* TIOCNOTTY */ 1587 } 1588 /* Reinitialize the log (because of the fork above). */ 1589 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1590 1591 /* Initialize the random number generator. */ 1592 arc4random_stir(); 1593 1594 /* Chdir to the root directory so that the current disk can be 1595 unmounted if desired. */ 1596 chdir("/"); 1597 1598 /* ignore SIGPIPE */ 1599 signal(SIGPIPE, SIG_IGN); 1600 1601 /* Get a connection, either from inetd or a listening TCP socket */ 1602 if (inetd_flag) { 1603 server_accept_inetd(&sock_in, &sock_out); 1604 1605 if ((options.protocol & SSH_PROTO_1) && 1606 sensitive_data.server_key == NULL) 1607 generate_ephemeral_server_key(); 1608 } else { 1609 server_listen(); 1610 1611 if (options.protocol & SSH_PROTO_1) 1612 generate_ephemeral_server_key(); 1613 1614 signal(SIGHUP, sighup_handler); 1615 signal(SIGCHLD, main_sigchld_handler); 1616 signal(SIGTERM, sigterm_handler); 1617 signal(SIGQUIT, sigterm_handler); 1618 1619 /* 1620 * Write out the pid file after the sigterm handler 1621 * is setup and the listen sockets are bound 1622 */ 1623 if (!debug_flag) { 1624 FILE *f = fopen(options.pid_file, "w"); 1625 1626 if (f == NULL) { 1627 error("Couldn't create pid file \"%s\": %s", 1628 options.pid_file, strerror(errno)); 1629 } else { 1630 fprintf(f, "%ld\n", (long) getpid()); 1631 fclose(f); 1632 } 1633 } 1634 1635 /* Accept a connection and return in a forked child */ 1636 server_accept_loop(&sock_in, &sock_out, 1637 &newsock, config_s); 1638 } 1639 1640 /* This is the child processing a new connection. */ 1641 setproctitle("%s", "[accepted]"); 1642 1643 /* 1644 * Create a new session and process group since the 4.4BSD 1645 * setlogin() affects the entire process group. We don't 1646 * want the child to be able to affect the parent. 1647 */ 1648 #if !defined(SSHD_ACQUIRES_CTTY) 1649 /* 1650 * If setsid is called, on some platforms sshd will later acquire a 1651 * controlling terminal which will result in "could not set 1652 * controlling tty" errors. 1653 */ 1654 if (!debug_flag && !inetd_flag && setsid() < 0) 1655 error("setsid: %.100s", strerror(errno)); 1656 #endif 1657 1658 if (rexec_flag) { 1659 int fd; 1660 1661 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1662 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1663 dup2(newsock, STDIN_FILENO); 1664 dup2(STDIN_FILENO, STDOUT_FILENO); 1665 if (startup_pipe == -1) 1666 close(REEXEC_STARTUP_PIPE_FD); 1667 else 1668 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1669 1670 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1671 close(config_s[1]); 1672 if (startup_pipe != -1) 1673 close(startup_pipe); 1674 1675 execv(rexec_argv[0], rexec_argv); 1676 1677 /* Reexec has failed, fall back and continue */ 1678 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1679 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1680 log_init(__progname, options.log_level, 1681 options.log_facility, log_stderr); 1682 1683 /* Clean up fds */ 1684 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1685 close(config_s[1]); 1686 close(REEXEC_CONFIG_PASS_FD); 1687 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1688 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1689 dup2(fd, STDIN_FILENO); 1690 dup2(fd, STDOUT_FILENO); 1691 if (fd > STDERR_FILENO) 1692 close(fd); 1693 } 1694 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1695 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1696 } 1697 1698 /* 1699 * Disable the key regeneration alarm. We will not regenerate the 1700 * key since we are no longer in a position to give it to anyone. We 1701 * will not restart on SIGHUP since it no longer makes sense. 1702 */ 1703 alarm(0); 1704 signal(SIGALRM, SIG_DFL); 1705 signal(SIGHUP, SIG_DFL); 1706 signal(SIGTERM, SIG_DFL); 1707 signal(SIGQUIT, SIG_DFL); 1708 signal(SIGCHLD, SIG_DFL); 1709 signal(SIGINT, SIG_DFL); 1710 1711 #ifdef __FreeBSD__ 1712 /* 1713 * Initialize the resolver. This may not happen automatically 1714 * before privsep chroot(). 1715 */ 1716 if ((_res.options & RES_INIT) == 0) { 1717 debug("res_init()"); 1718 res_init(); 1719 } 1720 #ifdef GSSAPI 1721 /* 1722 * Force GSS-API to parse its configuration and load any 1723 * mechanism plugins. 1724 */ 1725 { 1726 gss_OID_set mechs; 1727 OM_uint32 minor_status; 1728 gss_indicate_mechs(&minor_status, &mechs); 1729 gss_release_oid_set(&minor_status, &mechs); 1730 } 1731 #endif 1732 #endif 1733 1734 /* 1735 * Register our connection. This turns encryption off because we do 1736 * not have a key. 1737 */ 1738 packet_set_connection(sock_in, sock_out); 1739 packet_set_server(); 1740 1741 /* Set SO_KEEPALIVE if requested. */ 1742 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1743 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1744 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1745 1746 if ((remote_port = get_remote_port()) < 0) { 1747 debug("get_remote_port failed"); 1748 cleanup_exit(255); 1749 } 1750 1751 /* 1752 * We use get_canonical_hostname with usedns = 0 instead of 1753 * get_remote_ipaddr here so IP options will be checked. 1754 */ 1755 (void) get_canonical_hostname(0); 1756 /* 1757 * The rest of the code depends on the fact that 1758 * get_remote_ipaddr() caches the remote ip, even if 1759 * the socket goes away. 1760 */ 1761 remote_ip = get_remote_ipaddr(); 1762 1763 #ifdef SSH_AUDIT_EVENTS 1764 audit_connection_from(remote_ip, remote_port); 1765 #endif 1766 #ifdef LIBWRAP 1767 /* Check whether logins are denied from this host. */ 1768 if (packet_connection_is_on_socket()) { 1769 struct request_info req; 1770 1771 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 1772 fromhost(&req); 1773 1774 if (!hosts_access(&req)) { 1775 debug("Connection refused by tcp wrapper"); 1776 refuse(&req); 1777 /* NOTREACHED */ 1778 fatal("libwrap refuse returns"); 1779 } 1780 } 1781 #endif /* LIBWRAP */ 1782 1783 /* Log the connection. */ 1784 verbose("Connection from %.500s port %d", remote_ip, remote_port); 1785 1786 /* 1787 * We don't want to listen forever unless the other side 1788 * successfully authenticates itself. So we set up an alarm which is 1789 * cleared after successful authentication. A limit of zero 1790 * indicates no limit. Note that we don't set the alarm in debugging 1791 * mode; it is just annoying to have the server exit just when you 1792 * are about to discover the bug. 1793 */ 1794 signal(SIGALRM, grace_alarm_handler); 1795 if (!debug_flag) 1796 alarm(options.login_grace_time); 1797 1798 sshd_exchange_identification(sock_in, sock_out); 1799 1800 packet_set_nonblocking(); 1801 1802 /* allocate authentication context */ 1803 authctxt = xcalloc(1, sizeof(*authctxt)); 1804 1805 authctxt->loginmsg = &loginmsg; 1806 1807 /* XXX global for cleanup, access from other modules */ 1808 the_authctxt = authctxt; 1809 1810 /* prepare buffer to collect messages to display to user after login */ 1811 buffer_init(&loginmsg); 1812 1813 if (use_privsep) 1814 if (privsep_preauth(authctxt) == 1) 1815 goto authenticated; 1816 1817 /* perform the key exchange */ 1818 /* authenticate user and start session */ 1819 if (compat20) { 1820 do_ssh2_kex(); 1821 do_authentication2(authctxt); 1822 } else { 1823 do_ssh1_kex(); 1824 do_authentication(authctxt); 1825 } 1826 /* 1827 * If we use privilege separation, the unprivileged child transfers 1828 * the current keystate and exits 1829 */ 1830 if (use_privsep) { 1831 mm_send_keystate(pmonitor); 1832 exit(0); 1833 } 1834 1835 authenticated: 1836 /* 1837 * Cancel the alarm we set to limit the time taken for 1838 * authentication. 1839 */ 1840 alarm(0); 1841 signal(SIGALRM, SIG_DFL); 1842 authctxt->authenticated = 1; 1843 if (startup_pipe != -1) { 1844 close(startup_pipe); 1845 startup_pipe = -1; 1846 } 1847 1848 #ifdef SSH_AUDIT_EVENTS 1849 audit_event(SSH_AUTH_SUCCESS); 1850 #endif 1851 1852 /* 1853 * In privilege separation, we fork another child and prepare 1854 * file descriptor passing. 1855 */ 1856 if (use_privsep) { 1857 privsep_postauth(authctxt); 1858 /* the monitor process [priv] will not return */ 1859 if (!compat20) 1860 destroy_sensitive_data(); 1861 } 1862 1863 /* Start session. */ 1864 do_authenticated(authctxt); 1865 1866 /* The connection has been terminated. */ 1867 verbose("Closing connection to %.100s", remote_ip); 1868 1869 #ifdef USE_PAM 1870 if (options.use_pam) 1871 finish_pam(); 1872 #endif /* USE_PAM */ 1873 1874 #ifdef SSH_AUDIT_EVENTS 1875 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 1876 #endif 1877 1878 packet_close(); 1879 1880 if (use_privsep) 1881 mm_terminate(); 1882 1883 exit(0); 1884 } 1885 1886 /* 1887 * Decrypt session_key_int using our private server key and private host key 1888 * (key with larger modulus first). 1889 */ 1890 int 1891 ssh1_session_key(BIGNUM *session_key_int) 1892 { 1893 int rsafail = 0; 1894 1895 if (BN_cmp(sensitive_data.server_key->rsa->n, 1896 sensitive_data.ssh1_host_key->rsa->n) > 0) { 1897 /* Server key has bigger modulus. */ 1898 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 1899 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1900 SSH_KEY_BITS_RESERVED) { 1901 fatal("do_connection: %s: " 1902 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 1903 get_remote_ipaddr(), 1904 BN_num_bits(sensitive_data.server_key->rsa->n), 1905 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 1906 SSH_KEY_BITS_RESERVED); 1907 } 1908 if (rsa_private_decrypt(session_key_int, session_key_int, 1909 sensitive_data.server_key->rsa) <= 0) 1910 rsafail++; 1911 if (rsa_private_decrypt(session_key_int, session_key_int, 1912 sensitive_data.ssh1_host_key->rsa) <= 0) 1913 rsafail++; 1914 } else { 1915 /* Host key has bigger modulus (or they are equal). */ 1916 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 1917 BN_num_bits(sensitive_data.server_key->rsa->n) + 1918 SSH_KEY_BITS_RESERVED) { 1919 fatal("do_connection: %s: " 1920 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 1921 get_remote_ipaddr(), 1922 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 1923 BN_num_bits(sensitive_data.server_key->rsa->n), 1924 SSH_KEY_BITS_RESERVED); 1925 } 1926 if (rsa_private_decrypt(session_key_int, session_key_int, 1927 sensitive_data.ssh1_host_key->rsa) < 0) 1928 rsafail++; 1929 if (rsa_private_decrypt(session_key_int, session_key_int, 1930 sensitive_data.server_key->rsa) < 0) 1931 rsafail++; 1932 } 1933 return (rsafail); 1934 } 1935 /* 1936 * SSH1 key exchange 1937 */ 1938 static void 1939 do_ssh1_kex(void) 1940 { 1941 int i, len; 1942 int rsafail = 0; 1943 BIGNUM *session_key_int; 1944 u_char session_key[SSH_SESSION_KEY_LENGTH]; 1945 u_char cookie[8]; 1946 u_int cipher_type, auth_mask, protocol_flags; 1947 u_int32_t rnd = 0; 1948 1949 /* 1950 * Generate check bytes that the client must send back in the user 1951 * packet in order for it to be accepted; this is used to defy ip 1952 * spoofing attacks. Note that this only works against somebody 1953 * doing IP spoofing from a remote machine; any machine on the local 1954 * network can still see outgoing packets and catch the random 1955 * cookie. This only affects rhosts authentication, and this is one 1956 * of the reasons why it is inherently insecure. 1957 */ 1958 for (i = 0; i < 8; i++) { 1959 if (i % 4 == 0) 1960 rnd = arc4random(); 1961 cookie[i] = rnd & 0xff; 1962 rnd >>= 8; 1963 } 1964 1965 /* 1966 * Send our public key. We include in the packet 64 bits of random 1967 * data that must be matched in the reply in order to prevent IP 1968 * spoofing. 1969 */ 1970 packet_start(SSH_SMSG_PUBLIC_KEY); 1971 for (i = 0; i < 8; i++) 1972 packet_put_char(cookie[i]); 1973 1974 /* Store our public server RSA key. */ 1975 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 1976 packet_put_bignum(sensitive_data.server_key->rsa->e); 1977 packet_put_bignum(sensitive_data.server_key->rsa->n); 1978 1979 /* Store our public host RSA key. */ 1980 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 1981 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 1982 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 1983 1984 /* Put protocol flags. */ 1985 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 1986 1987 /* Declare which ciphers we support. */ 1988 packet_put_int(cipher_mask_ssh1(0)); 1989 1990 /* Declare supported authentication types. */ 1991 auth_mask = 0; 1992 if (options.rhosts_rsa_authentication) 1993 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 1994 if (options.rsa_authentication) 1995 auth_mask |= 1 << SSH_AUTH_RSA; 1996 if (options.challenge_response_authentication == 1) 1997 auth_mask |= 1 << SSH_AUTH_TIS; 1998 if (options.password_authentication) 1999 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2000 packet_put_int(auth_mask); 2001 2002 /* Send the packet and wait for it to be sent. */ 2003 packet_send(); 2004 packet_write_wait(); 2005 2006 debug("Sent %d bit server key and %d bit host key.", 2007 BN_num_bits(sensitive_data.server_key->rsa->n), 2008 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2009 2010 /* Read clients reply (cipher type and session key). */ 2011 packet_read_expect(SSH_CMSG_SESSION_KEY); 2012 2013 /* Get cipher type and check whether we accept this. */ 2014 cipher_type = packet_get_char(); 2015 2016 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2017 packet_disconnect("Warning: client selects unsupported cipher."); 2018 2019 /* Get check bytes from the packet. These must match those we 2020 sent earlier with the public key packet. */ 2021 for (i = 0; i < 8; i++) 2022 if (cookie[i] != packet_get_char()) 2023 packet_disconnect("IP Spoofing check bytes do not match."); 2024 2025 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2026 2027 /* Get the encrypted integer. */ 2028 if ((session_key_int = BN_new()) == NULL) 2029 fatal("do_ssh1_kex: BN_new failed"); 2030 packet_get_bignum(session_key_int); 2031 2032 protocol_flags = packet_get_int(); 2033 packet_set_protocol_flags(protocol_flags); 2034 packet_check_eom(); 2035 2036 /* Decrypt session_key_int using host/server keys */ 2037 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2038 2039 /* 2040 * Extract session key from the decrypted integer. The key is in the 2041 * least significant 256 bits of the integer; the first byte of the 2042 * key is in the highest bits. 2043 */ 2044 if (!rsafail) { 2045 BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2046 len = BN_num_bytes(session_key_int); 2047 if (len < 0 || (u_int)len > sizeof(session_key)) { 2048 error("do_connection: bad session key len from %s: " 2049 "session_key_int %d > sizeof(session_key) %lu", 2050 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2051 rsafail++; 2052 } else { 2053 memset(session_key, 0, sizeof(session_key)); 2054 BN_bn2bin(session_key_int, 2055 session_key + sizeof(session_key) - len); 2056 2057 derive_ssh1_session_id( 2058 sensitive_data.ssh1_host_key->rsa->n, 2059 sensitive_data.server_key->rsa->n, 2060 cookie, session_id); 2061 /* 2062 * Xor the first 16 bytes of the session key with the 2063 * session id. 2064 */ 2065 for (i = 0; i < 16; i++) 2066 session_key[i] ^= session_id[i]; 2067 } 2068 } 2069 if (rsafail) { 2070 int bytes = BN_num_bytes(session_key_int); 2071 u_char *buf = xmalloc(bytes); 2072 MD5_CTX md; 2073 2074 logit("do_connection: generating a fake encryption key"); 2075 BN_bn2bin(session_key_int, buf); 2076 MD5_Init(&md); 2077 MD5_Update(&md, buf, bytes); 2078 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2079 MD5_Final(session_key, &md); 2080 MD5_Init(&md); 2081 MD5_Update(&md, session_key, 16); 2082 MD5_Update(&md, buf, bytes); 2083 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2084 MD5_Final(session_key + 16, &md); 2085 memset(buf, 0, bytes); 2086 xfree(buf); 2087 for (i = 0; i < 16; i++) 2088 session_id[i] = session_key[i] ^ session_key[i + 16]; 2089 } 2090 /* Destroy the private and public keys. No longer. */ 2091 destroy_sensitive_data(); 2092 2093 if (use_privsep) 2094 mm_ssh1_session_id(session_id); 2095 2096 /* Destroy the decrypted integer. It is no longer needed. */ 2097 BN_clear_free(session_key_int); 2098 2099 /* Set the session key. From this on all communications will be encrypted. */ 2100 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2101 2102 /* Destroy our copy of the session key. It is no longer needed. */ 2103 memset(session_key, 0, sizeof(session_key)); 2104 2105 debug("Received session key; encryption turned on."); 2106 2107 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2108 packet_start(SSH_SMSG_SUCCESS); 2109 packet_send(); 2110 packet_write_wait(); 2111 } 2112 2113 /* 2114 * SSH2 key exchange: diffie-hellman-group1-sha1 2115 */ 2116 static void 2117 do_ssh2_kex(void) 2118 { 2119 Kex *kex; 2120 2121 if (options.ciphers != NULL) { 2122 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2123 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2124 } 2125 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2126 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2127 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2128 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2129 2130 if (options.macs != NULL) { 2131 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2132 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2133 } 2134 if (options.compression == COMP_NONE) { 2135 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2136 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2137 } else if (options.compression == COMP_DELAYED) { 2138 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2139 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2140 } 2141 2142 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); 2143 2144 /* start key exchange */ 2145 kex = kex_setup(myproposal); 2146 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2147 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2148 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2149 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2150 kex->server = 1; 2151 kex->client_version_string=client_version_string; 2152 kex->server_version_string=server_version_string; 2153 kex->load_host_key=&get_hostkey_by_type; 2154 kex->host_key_index=&get_hostkey_index; 2155 2156 xxx_kex = kex; 2157 2158 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2159 2160 session_id2 = kex->session_id; 2161 session_id2_len = kex->session_id_len; 2162 2163 #ifdef DEBUG_KEXDH 2164 /* send 1st encrypted/maced/compressed message */ 2165 packet_start(SSH2_MSG_IGNORE); 2166 packet_put_cstring("markus"); 2167 packet_send(); 2168 packet_write_wait(); 2169 #endif 2170 debug("KEX done"); 2171 } 2172 2173 /* server specific fatal cleanup */ 2174 void 2175 cleanup_exit(int i) 2176 { 2177 if (the_authctxt) 2178 do_cleanup(the_authctxt); 2179 #ifdef SSH_AUDIT_EVENTS 2180 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2181 if (!use_privsep || mm_is_monitor()) 2182 audit_event(SSH_CONNECTION_ABANDON); 2183 #endif 2184 _exit(i); 2185 } 2186