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 "includes.h" 46 __RCSID("$FreeBSD$"); 47 48 #include <sys/types.h> 49 #include <sys/ioctl.h> 50 #include <sys/mman.h> 51 #include <sys/socket.h> 52 #ifdef HAVE_SYS_STAT_H 53 # include <sys/stat.h> 54 #endif 55 #ifdef HAVE_SYS_TIME_H 56 # include <sys/time.h> 57 #endif 58 #include "openbsd-compat/sys-tree.h" 59 #include "openbsd-compat/sys-queue.h" 60 #include <sys/wait.h> 61 62 #include <errno.h> 63 #include <fcntl.h> 64 #include <netdb.h> 65 #ifdef HAVE_PATHS_H 66 #include <paths.h> 67 #endif 68 #include <grp.h> 69 #include <pwd.h> 70 #include <signal.h> 71 #include <stdarg.h> 72 #include <stdio.h> 73 #include <stdlib.h> 74 #include <string.h> 75 #include <unistd.h> 76 77 #include <openssl/dh.h> 78 #include <openssl/bn.h> 79 #include <openssl/md5.h> 80 #include <openssl/rand.h> 81 #include "openbsd-compat/openssl-compat.h" 82 83 #ifdef HAVE_SECUREWARE 84 #include <sys/security.h> 85 #include <prot.h> 86 #endif 87 88 #ifdef __FreeBSD__ 89 #include <resolv.h> 90 #if defined(GSSAPI) && defined(HAVE_GSSAPI_H) 91 #include <gssapi.h> 92 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H) 93 #include <gssapi/gssapi.h> 94 #endif 95 #endif 96 97 #include "xmalloc.h" 98 #include "ssh.h" 99 #include "ssh1.h" 100 #include "ssh2.h" 101 #include "rsa.h" 102 #include "sshpty.h" 103 #include "packet.h" 104 #include "log.h" 105 #include "buffer.h" 106 #include "servconf.h" 107 #include "uidswap.h" 108 #include "compat.h" 109 #include "cipher.h" 110 #include "key.h" 111 #include "kex.h" 112 #include "dh.h" 113 #include "myproposal.h" 114 #include "authfile.h" 115 #include "pathnames.h" 116 #include "atomicio.h" 117 #include "canohost.h" 118 #include "hostfile.h" 119 #include "auth.h" 120 #include "misc.h" 121 #include "msg.h" 122 #include "dispatch.h" 123 #include "channels.h" 124 #include "session.h" 125 #include "monitor_mm.h" 126 #include "monitor.h" 127 #ifdef GSSAPI 128 #include "ssh-gss.h" 129 #endif 130 #include "monitor_wrap.h" 131 #include "roaming.h" 132 #include "version.h" 133 134 #ifdef LIBWRAP 135 #include <tcpd.h> 136 #include <syslog.h> 137 int allow_severity; 138 int deny_severity; 139 #endif /* LIBWRAP */ 140 141 #ifndef O_NOCTTY 142 #define O_NOCTTY 0 143 #endif 144 145 /* Re-exec fds */ 146 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 147 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 148 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 149 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 150 151 extern char *__progname; 152 153 /* Server configuration options. */ 154 ServerOptions options; 155 156 /* Name of the server configuration file. */ 157 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 158 159 /* 160 * Debug mode flag. This can be set on the command line. If debug 161 * mode is enabled, extra debugging output will be sent to the system 162 * log, the daemon will not go to background, and will exit after processing 163 * the first connection. 164 */ 165 int debug_flag = 0; 166 167 /* Flag indicating that the daemon should only test the configuration and keys. */ 168 int test_flag = 0; 169 170 /* Flag indicating that the daemon is being started from inetd. */ 171 int inetd_flag = 0; 172 173 /* Flag indicating that sshd should not detach and become a daemon. */ 174 int no_daemon_flag = 0; 175 176 /* debug goes to stderr unless inetd_flag is set */ 177 int log_stderr = 0; 178 179 /* Saved arguments to main(). */ 180 char **saved_argv; 181 int saved_argc; 182 183 /* re-exec */ 184 int rexeced_flag = 0; 185 int rexec_flag = 1; 186 int rexec_argc = 0; 187 char **rexec_argv; 188 189 /* 190 * The sockets that the server is listening; this is used in the SIGHUP 191 * signal handler. 192 */ 193 #define MAX_LISTEN_SOCKS 16 194 int listen_socks[MAX_LISTEN_SOCKS]; 195 int num_listen_socks = 0; 196 197 /* 198 * the client's version string, passed by sshd2 in compat mode. if != NULL, 199 * sshd will skip the version-number exchange 200 */ 201 char *client_version_string = NULL; 202 char *server_version_string = NULL; 203 204 /* for rekeying XXX fixme */ 205 Kex *xxx_kex; 206 207 /* 208 * Any really sensitive data in the application is contained in this 209 * structure. The idea is that this structure could be locked into memory so 210 * that the pages do not get written into swap. However, there are some 211 * problems. The private key contains BIGNUMs, and we do not (in principle) 212 * have access to the internals of them, and locking just the structure is 213 * not very useful. Currently, memory locking is not implemented. 214 */ 215 struct { 216 Key *server_key; /* ephemeral server key */ 217 Key *ssh1_host_key; /* ssh1 host key */ 218 Key **host_keys; /* all private host keys */ 219 int have_ssh1_key; 220 int have_ssh2_key; 221 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 222 } sensitive_data; 223 224 /* 225 * Flag indicating whether the RSA server key needs to be regenerated. 226 * Is set in the SIGALRM handler and cleared when the key is regenerated. 227 */ 228 static volatile sig_atomic_t key_do_regen = 0; 229 230 /* This is set to true when a signal is received. */ 231 static volatile sig_atomic_t received_sighup = 0; 232 static volatile sig_atomic_t received_sigterm = 0; 233 234 /* session identifier, used by RSA-auth */ 235 u_char session_id[16]; 236 237 /* same for ssh2 */ 238 u_char *session_id2 = NULL; 239 u_int session_id2_len = 0; 240 241 /* record remote hostname or ip */ 242 u_int utmp_len = MAXHOSTNAMELEN; 243 244 /* options.max_startup sized array of fd ints */ 245 int *startup_pipes = NULL; 246 int startup_pipe; /* in child */ 247 248 /* variables used for privilege separation */ 249 int use_privsep = -1; 250 struct monitor *pmonitor = NULL; 251 252 /* global authentication context */ 253 Authctxt *the_authctxt = NULL; 254 255 /* sshd_config buffer */ 256 Buffer cfg; 257 258 /* message to be displayed after login */ 259 Buffer loginmsg; 260 261 /* Unprivileged user */ 262 struct passwd *privsep_pw = NULL; 263 264 /* Prototypes for various functions defined later in this file. */ 265 void destroy_sensitive_data(void); 266 void demote_sensitive_data(void); 267 268 static void do_ssh1_kex(void); 269 static void do_ssh2_kex(void); 270 271 /* 272 * Close all listening sockets 273 */ 274 static void 275 close_listen_socks(void) 276 { 277 int i; 278 279 for (i = 0; i < num_listen_socks; i++) 280 close(listen_socks[i]); 281 num_listen_socks = -1; 282 } 283 284 static void 285 close_startup_pipes(void) 286 { 287 int i; 288 289 if (startup_pipes) 290 for (i = 0; i < options.max_startups; i++) 291 if (startup_pipes[i] != -1) 292 close(startup_pipes[i]); 293 } 294 295 /* 296 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 297 * the effect is to reread the configuration file (and to regenerate 298 * the server key). 299 */ 300 301 /*ARGSUSED*/ 302 static void 303 sighup_handler(int sig) 304 { 305 int save_errno = errno; 306 307 received_sighup = 1; 308 signal(SIGHUP, sighup_handler); 309 errno = save_errno; 310 } 311 312 /* 313 * Called from the main program after receiving SIGHUP. 314 * Restarts the server. 315 */ 316 static void 317 sighup_restart(void) 318 { 319 logit("Received SIGHUP; restarting."); 320 close_listen_socks(); 321 close_startup_pipes(); 322 alarm(0); /* alarm timer persists across exec */ 323 execv(saved_argv[0], saved_argv); 324 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 325 strerror(errno)); 326 exit(1); 327 } 328 329 /* 330 * Generic signal handler for terminating signals in the master daemon. 331 */ 332 /*ARGSUSED*/ 333 static void 334 sigterm_handler(int sig) 335 { 336 received_sigterm = sig; 337 } 338 339 /* 340 * SIGCHLD handler. This is called whenever a child dies. This will then 341 * reap any zombies left by exited children. 342 */ 343 /*ARGSUSED*/ 344 static void 345 main_sigchld_handler(int sig) 346 { 347 int save_errno = errno; 348 pid_t pid; 349 int status; 350 351 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 352 (pid < 0 && errno == EINTR)) 353 ; 354 355 signal(SIGCHLD, main_sigchld_handler); 356 errno = save_errno; 357 } 358 359 /* 360 * Signal handler for the alarm after the login grace period has expired. 361 */ 362 /*ARGSUSED*/ 363 static void 364 grace_alarm_handler(int sig) 365 { 366 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 367 kill(pmonitor->m_pid, SIGALRM); 368 369 /* Log error and exit. */ 370 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 371 } 372 373 /* 374 * Signal handler for the key regeneration alarm. Note that this 375 * alarm only occurs in the daemon waiting for connections, and it does not 376 * do anything with the private key or random state before forking. 377 * Thus there should be no concurrency control/asynchronous execution 378 * problems. 379 */ 380 static void 381 generate_ephemeral_server_key(void) 382 { 383 verbose("Generating %s%d bit RSA key.", 384 sensitive_data.server_key ? "new " : "", options.server_key_bits); 385 if (sensitive_data.server_key != NULL) 386 key_free(sensitive_data.server_key); 387 sensitive_data.server_key = key_generate(KEY_RSA1, 388 options.server_key_bits); 389 verbose("RSA key generation complete."); 390 391 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 392 arc4random_stir(); 393 } 394 395 /*ARGSUSED*/ 396 static void 397 key_regeneration_alarm(int sig) 398 { 399 int save_errno = errno; 400 401 signal(SIGALRM, SIG_DFL); 402 errno = save_errno; 403 key_do_regen = 1; 404 } 405 406 static void 407 sshd_exchange_identification(int sock_in, int sock_out) 408 { 409 u_int i; 410 int mismatch; 411 int remote_major, remote_minor; 412 int major, minor; 413 char *s, *newline = "\n"; 414 char buf[256]; /* Must not be larger than remote_version. */ 415 char remote_version[256]; /* Must be at least as big as buf. */ 416 417 if ((options.protocol & SSH_PROTO_1) && 418 (options.protocol & SSH_PROTO_2)) { 419 major = PROTOCOL_MAJOR_1; 420 minor = 99; 421 } else if (options.protocol & SSH_PROTO_2) { 422 major = PROTOCOL_MAJOR_2; 423 minor = PROTOCOL_MINOR_2; 424 newline = "\r\n"; 425 } else { 426 major = PROTOCOL_MAJOR_1; 427 minor = PROTOCOL_MINOR_1; 428 } 429 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor, 430 SSH_VERSION, newline); 431 server_version_string = xstrdup(buf); 432 433 /* Send our protocol version identification. */ 434 if (roaming_atomicio(vwrite, sock_out, server_version_string, 435 strlen(server_version_string)) 436 != strlen(server_version_string)) { 437 logit("Could not write ident string to %s", get_remote_ipaddr()); 438 cleanup_exit(255); 439 } 440 441 /* Read other sides version identification. */ 442 memset(buf, 0, sizeof(buf)); 443 for (i = 0; i < sizeof(buf) - 1; i++) { 444 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 445 logit("Did not receive identification string from %s", 446 get_remote_ipaddr()); 447 cleanup_exit(255); 448 } 449 if (buf[i] == '\r') { 450 buf[i] = 0; 451 /* Kludge for F-Secure Macintosh < 1.0.2 */ 452 if (i == 12 && 453 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 454 break; 455 continue; 456 } 457 if (buf[i] == '\n') { 458 buf[i] = 0; 459 break; 460 } 461 } 462 buf[sizeof(buf) - 1] = 0; 463 client_version_string = xstrdup(buf); 464 465 /* 466 * Check that the versions match. In future this might accept 467 * several versions and set appropriate flags to handle them. 468 */ 469 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 470 &remote_major, &remote_minor, remote_version) != 3) { 471 s = "Protocol mismatch.\n"; 472 (void) atomicio(vwrite, sock_out, s, strlen(s)); 473 close(sock_in); 474 close(sock_out); 475 logit("Bad protocol version identification '%.100s' from %s", 476 client_version_string, get_remote_ipaddr()); 477 cleanup_exit(255); 478 } 479 debug("Client protocol version %d.%d; client software version %.100s", 480 remote_major, remote_minor, remote_version); 481 482 compat_datafellows(remote_version); 483 484 if (datafellows & SSH_BUG_PROBE) { 485 logit("probed from %s with %s. Don't panic.", 486 get_remote_ipaddr(), client_version_string); 487 cleanup_exit(255); 488 } 489 490 if (datafellows & SSH_BUG_SCANNER) { 491 logit("scanned from %s with %s. Don't panic.", 492 get_remote_ipaddr(), client_version_string); 493 cleanup_exit(255); 494 } 495 496 mismatch = 0; 497 switch (remote_major) { 498 case 1: 499 if (remote_minor == 99) { 500 if (options.protocol & SSH_PROTO_2) 501 enable_compat20(); 502 else 503 mismatch = 1; 504 break; 505 } 506 if (!(options.protocol & SSH_PROTO_1)) { 507 mismatch = 1; 508 break; 509 } 510 if (remote_minor < 3) { 511 packet_disconnect("Your ssh version is too old and " 512 "is no longer supported. Please install a newer version."); 513 } else if (remote_minor == 3) { 514 /* note that this disables agent-forwarding */ 515 enable_compat13(); 516 } 517 break; 518 case 2: 519 if (options.protocol & SSH_PROTO_2) { 520 enable_compat20(); 521 break; 522 } 523 /* FALLTHROUGH */ 524 default: 525 mismatch = 1; 526 break; 527 } 528 chop(server_version_string); 529 debug("Local version string %.200s", server_version_string); 530 531 if (mismatch) { 532 s = "Protocol major versions differ.\n"; 533 (void) atomicio(vwrite, sock_out, s, strlen(s)); 534 close(sock_in); 535 close(sock_out); 536 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 537 get_remote_ipaddr(), 538 server_version_string, client_version_string); 539 cleanup_exit(255); 540 } 541 } 542 543 /* Destroy the host and server keys. They will no longer be needed. */ 544 void 545 destroy_sensitive_data(void) 546 { 547 int i; 548 549 if (sensitive_data.server_key) { 550 key_free(sensitive_data.server_key); 551 sensitive_data.server_key = NULL; 552 } 553 for (i = 0; i < options.num_host_key_files; i++) { 554 if (sensitive_data.host_keys[i]) { 555 key_free(sensitive_data.host_keys[i]); 556 sensitive_data.host_keys[i] = NULL; 557 } 558 } 559 sensitive_data.ssh1_host_key = NULL; 560 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); 561 } 562 563 /* Demote private to public keys for network child */ 564 void 565 demote_sensitive_data(void) 566 { 567 Key *tmp; 568 int i; 569 570 if (sensitive_data.server_key) { 571 tmp = key_demote(sensitive_data.server_key); 572 key_free(sensitive_data.server_key); 573 sensitive_data.server_key = tmp; 574 } 575 576 for (i = 0; i < options.num_host_key_files; i++) { 577 if (sensitive_data.host_keys[i]) { 578 tmp = key_demote(sensitive_data.host_keys[i]); 579 key_free(sensitive_data.host_keys[i]); 580 sensitive_data.host_keys[i] = tmp; 581 if (tmp->type == KEY_RSA1) 582 sensitive_data.ssh1_host_key = tmp; 583 } 584 } 585 586 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 587 } 588 589 static void 590 privsep_preauth_child(void) 591 { 592 u_int32_t rnd[256]; 593 gid_t gidset[1]; 594 595 /* Enable challenge-response authentication for privilege separation */ 596 privsep_challenge_enable(); 597 598 arc4random_stir(); 599 arc4random_buf(rnd, sizeof(rnd)); 600 RAND_seed(rnd, sizeof(rnd)); 601 602 /* Demote the private keys to public keys. */ 603 demote_sensitive_data(); 604 605 /* Change our root directory */ 606 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 607 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 608 strerror(errno)); 609 if (chdir("/") == -1) 610 fatal("chdir(\"/\"): %s", strerror(errno)); 611 612 /* Drop our privileges */ 613 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 614 (u_int)privsep_pw->pw_gid); 615 #if 0 616 /* XXX not ready, too heavy after chroot */ 617 do_setusercontext(privsep_pw); 618 #else 619 gidset[0] = privsep_pw->pw_gid; 620 if (setgroups(1, gidset) < 0) 621 fatal("setgroups: %.100s", strerror(errno)); 622 permanently_set_uid(privsep_pw); 623 #endif 624 } 625 626 static int 627 privsep_preauth(Authctxt *authctxt) 628 { 629 int status; 630 pid_t pid; 631 632 /* Set up unprivileged child process to deal with network data */ 633 pmonitor = monitor_init(); 634 /* Store a pointer to the kex for later rekeying */ 635 pmonitor->m_pkex = &xxx_kex; 636 637 pid = fork(); 638 if (pid == -1) { 639 fatal("fork of unprivileged child failed"); 640 } else if (pid != 0) { 641 debug2("Network child is on pid %ld", (long)pid); 642 643 close(pmonitor->m_recvfd); 644 pmonitor->m_pid = pid; 645 monitor_child_preauth(authctxt, pmonitor); 646 close(pmonitor->m_sendfd); 647 648 /* Sync memory */ 649 monitor_sync(pmonitor); 650 651 /* Wait for the child's exit status */ 652 while (waitpid(pid, &status, 0) < 0) 653 if (errno != EINTR) 654 break; 655 return (1); 656 } else { 657 /* child */ 658 659 close(pmonitor->m_sendfd); 660 661 /* Demote the child */ 662 if (getuid() == 0 || geteuid() == 0) 663 privsep_preauth_child(); 664 setproctitle("%s", "[net]"); 665 } 666 return (0); 667 } 668 669 static void 670 privsep_postauth(Authctxt *authctxt) 671 { 672 u_int32_t rnd[256]; 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 verbose("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 arc4random_stir(); 706 arc4random_buf(rnd, sizeof(rnd)); 707 RAND_seed(rnd, sizeof(rnd)); 708 709 /* Drop privileges */ 710 do_setusercontext(authctxt->pw); 711 712 skip: 713 /* It is safe now to apply the key state */ 714 monitor_apply_keystate(pmonitor); 715 716 /* 717 * Tell the packet layer that authentication was successful, since 718 * this information is not part of the key state. 719 */ 720 packet_set_authenticated(); 721 } 722 723 static char * 724 list_hostkey_types(void) 725 { 726 Buffer b; 727 const char *p; 728 char *ret; 729 int i; 730 731 buffer_init(&b); 732 for (i = 0; i < options.num_host_key_files; i++) { 733 Key *key = sensitive_data.host_keys[i]; 734 if (key == NULL) 735 continue; 736 switch (key->type) { 737 case KEY_RSA: 738 case KEY_DSA: 739 if (buffer_len(&b) > 0) 740 buffer_append(&b, ",", 1); 741 p = key_ssh_name(key); 742 buffer_append(&b, p, strlen(p)); 743 break; 744 } 745 } 746 buffer_append(&b, "\0", 1); 747 ret = xstrdup(buffer_ptr(&b)); 748 buffer_free(&b); 749 debug("list_hostkey_types: %s", ret); 750 return ret; 751 } 752 753 Key * 754 get_hostkey_by_type(int type) 755 { 756 int i; 757 758 for (i = 0; i < options.num_host_key_files; i++) { 759 Key *key = sensitive_data.host_keys[i]; 760 if (key != NULL && key->type == type) 761 return key; 762 } 763 return NULL; 764 } 765 766 Key * 767 get_hostkey_by_index(int ind) 768 { 769 if (ind < 0 || ind >= options.num_host_key_files) 770 return (NULL); 771 return (sensitive_data.host_keys[ind]); 772 } 773 774 int 775 get_hostkey_index(Key *key) 776 { 777 int i; 778 779 for (i = 0; i < options.num_host_key_files; i++) { 780 if (key == sensitive_data.host_keys[i]) 781 return (i); 782 } 783 return (-1); 784 } 785 786 /* 787 * returns 1 if connection should be dropped, 0 otherwise. 788 * dropping starts at connection #max_startups_begin with a probability 789 * of (max_startups_rate/100). the probability increases linearly until 790 * all connections are dropped for startups > max_startups 791 */ 792 static int 793 drop_connection(int startups) 794 { 795 int p, r; 796 797 if (startups < options.max_startups_begin) 798 return 0; 799 if (startups >= options.max_startups) 800 return 1; 801 if (options.max_startups_rate == 100) 802 return 1; 803 804 p = 100 - options.max_startups_rate; 805 p *= startups - options.max_startups_begin; 806 p /= options.max_startups - options.max_startups_begin; 807 p += options.max_startups_rate; 808 r = arc4random_uniform(100); 809 810 debug("drop_connection: p %d, r %d", p, r); 811 return (r < p) ? 1 : 0; 812 } 813 814 static void 815 usage(void) 816 { 817 fprintf(stderr, "%s, %s\n", 818 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); 819 fprintf(stderr, 820 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-f config_file]\n" 821 " [-g login_grace_time] [-h host_key_file] [-k key_gen_time]\n" 822 " [-o option] [-p port] [-u len]\n" 823 ); 824 exit(1); 825 } 826 827 static void 828 send_rexec_state(int fd, Buffer *conf) 829 { 830 Buffer m; 831 832 debug3("%s: entering fd = %d config len %d", __func__, fd, 833 buffer_len(conf)); 834 835 /* 836 * Protocol from reexec master to child: 837 * string configuration 838 * u_int ephemeral_key_follows 839 * bignum e (only if ephemeral_key_follows == 1) 840 * bignum n " 841 * bignum d " 842 * bignum iqmp " 843 * bignum p " 844 * bignum q " 845 * string rngseed (only if OpenSSL is not self-seeded) 846 */ 847 buffer_init(&m); 848 buffer_put_cstring(&m, buffer_ptr(conf)); 849 850 if (sensitive_data.server_key != NULL && 851 sensitive_data.server_key->type == KEY_RSA1) { 852 buffer_put_int(&m, 1); 853 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 854 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 855 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 856 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 857 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 858 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 859 } else 860 buffer_put_int(&m, 0); 861 862 #ifndef OPENSSL_PRNG_ONLY 863 rexec_send_rng_seed(&m); 864 #endif 865 866 if (ssh_msg_send(fd, 0, &m) == -1) 867 fatal("%s: ssh_msg_send failed", __func__); 868 869 buffer_free(&m); 870 871 debug3("%s: done", __func__); 872 } 873 874 static void 875 recv_rexec_state(int fd, Buffer *conf) 876 { 877 Buffer m; 878 char *cp; 879 u_int len; 880 881 debug3("%s: entering fd = %d", __func__, fd); 882 883 buffer_init(&m); 884 885 if (ssh_msg_recv(fd, &m) == -1) 886 fatal("%s: ssh_msg_recv failed", __func__); 887 if (buffer_get_char(&m) != 0) 888 fatal("%s: rexec version mismatch", __func__); 889 890 cp = buffer_get_string(&m, &len); 891 if (conf != NULL) 892 buffer_append(conf, cp, len + 1); 893 xfree(cp); 894 895 if (buffer_get_int(&m)) { 896 if (sensitive_data.server_key != NULL) 897 key_free(sensitive_data.server_key); 898 sensitive_data.server_key = key_new_private(KEY_RSA1); 899 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 900 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 901 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 902 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 903 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 904 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 905 rsa_generate_additional_parameters( 906 sensitive_data.server_key->rsa); 907 } 908 909 #ifndef OPENSSL_PRNG_ONLY 910 rexec_recv_rng_seed(&m); 911 #endif 912 913 buffer_free(&m); 914 915 debug3("%s: done", __func__); 916 } 917 918 /* Accept a connection from inetd */ 919 static void 920 server_accept_inetd(int *sock_in, int *sock_out) 921 { 922 int fd; 923 924 startup_pipe = -1; 925 if (rexeced_flag) { 926 close(REEXEC_CONFIG_PASS_FD); 927 *sock_in = *sock_out = dup(STDIN_FILENO); 928 if (!debug_flag) { 929 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 930 close(REEXEC_STARTUP_PIPE_FD); 931 } 932 } else { 933 *sock_in = dup(STDIN_FILENO); 934 *sock_out = dup(STDOUT_FILENO); 935 } 936 /* 937 * We intentionally do not close the descriptors 0, 1, and 2 938 * as our code for setting the descriptors won't work if 939 * ttyfd happens to be one of those. 940 */ 941 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 942 dup2(fd, STDIN_FILENO); 943 dup2(fd, STDOUT_FILENO); 944 if (fd > STDOUT_FILENO) 945 close(fd); 946 } 947 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 948 } 949 950 /* 951 * Listen for TCP connections 952 */ 953 static void 954 server_listen(void) 955 { 956 int ret, listen_sock, on = 1; 957 struct addrinfo *ai; 958 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 959 960 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 961 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 962 continue; 963 if (num_listen_socks >= MAX_LISTEN_SOCKS) 964 fatal("Too many listen sockets. " 965 "Enlarge MAX_LISTEN_SOCKS"); 966 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 967 ntop, sizeof(ntop), strport, sizeof(strport), 968 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 969 error("getnameinfo failed: %.100s", 970 ssh_gai_strerror(ret)); 971 continue; 972 } 973 /* Create socket for listening. */ 974 listen_sock = socket(ai->ai_family, ai->ai_socktype, 975 ai->ai_protocol); 976 if (listen_sock < 0) { 977 /* kernel may not support ipv6 */ 978 verbose("socket: %.100s", strerror(errno)); 979 continue; 980 } 981 if (set_nonblock(listen_sock) == -1) { 982 close(listen_sock); 983 continue; 984 } 985 /* 986 * Set socket options. 987 * Allow local port reuse in TIME_WAIT. 988 */ 989 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 990 &on, sizeof(on)) == -1) 991 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 992 993 #ifdef IPV6_V6ONLY 994 /* Only communicate in IPv6 over AF_INET6 sockets. */ 995 if (ai->ai_family == AF_INET6) { 996 if (setsockopt(listen_sock, IPPROTO_IPV6, IPV6_V6ONLY, 997 &on, sizeof(on)) == -1) 998 error("setsockopt IPV6_V6ONLY: %s", 999 strerror(errno)); 1000 } 1001 #endif 1002 1003 debug("Bind to port %s on %s.", strport, ntop); 1004 1005 /* Bind the socket to the desired port. */ 1006 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1007 error("Bind to port %s on %s failed: %.200s.", 1008 strport, ntop, strerror(errno)); 1009 close(listen_sock); 1010 continue; 1011 } 1012 listen_socks[num_listen_socks] = listen_sock; 1013 num_listen_socks++; 1014 1015 /* Start listening on the port. */ 1016 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1017 fatal("listen on [%s]:%s: %.100s", 1018 ntop, strport, strerror(errno)); 1019 logit("Server listening on %s port %s.", ntop, strport); 1020 } 1021 freeaddrinfo(options.listen_addrs); 1022 1023 if (!num_listen_socks) 1024 fatal("Cannot bind any address."); 1025 } 1026 1027 /* 1028 * The main TCP accept loop. Note that, for the non-debug case, returns 1029 * from this function are in a forked subprocess. 1030 */ 1031 static void 1032 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1033 { 1034 fd_set *fdset; 1035 int i, j, ret, maxfd; 1036 int key_used = 0, startups = 0; 1037 int startup_p[2] = { -1 , -1 }; 1038 struct sockaddr_storage from; 1039 socklen_t fromlen; 1040 pid_t pid; 1041 1042 /* setup fd set for accept */ 1043 fdset = NULL; 1044 maxfd = 0; 1045 for (i = 0; i < num_listen_socks; i++) 1046 if (listen_socks[i] > maxfd) 1047 maxfd = listen_socks[i]; 1048 /* pipes connected to unauthenticated childs */ 1049 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1050 for (i = 0; i < options.max_startups; i++) 1051 startup_pipes[i] = -1; 1052 1053 /* 1054 * Stay listening for connections until the system crashes or 1055 * the daemon is killed with a signal. 1056 */ 1057 for (;;) { 1058 if (received_sighup) 1059 sighup_restart(); 1060 if (fdset != NULL) 1061 xfree(fdset); 1062 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1063 sizeof(fd_mask)); 1064 1065 for (i = 0; i < num_listen_socks; i++) 1066 FD_SET(listen_socks[i], fdset); 1067 for (i = 0; i < options.max_startups; i++) 1068 if (startup_pipes[i] != -1) 1069 FD_SET(startup_pipes[i], fdset); 1070 1071 /* Wait in select until there is a connection. */ 1072 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1073 if (ret < 0 && errno != EINTR) 1074 error("select: %.100s", strerror(errno)); 1075 if (received_sigterm) { 1076 logit("Received signal %d; terminating.", 1077 (int) received_sigterm); 1078 close_listen_socks(); 1079 unlink(options.pid_file); 1080 exit(255); 1081 } 1082 if (key_used && key_do_regen) { 1083 generate_ephemeral_server_key(); 1084 key_used = 0; 1085 key_do_regen = 0; 1086 } 1087 if (ret < 0) 1088 continue; 1089 1090 for (i = 0; i < options.max_startups; i++) 1091 if (startup_pipes[i] != -1 && 1092 FD_ISSET(startup_pipes[i], fdset)) { 1093 /* 1094 * the read end of the pipe is ready 1095 * if the child has closed the pipe 1096 * after successful authentication 1097 * or if the child has died 1098 */ 1099 close(startup_pipes[i]); 1100 startup_pipes[i] = -1; 1101 startups--; 1102 } 1103 for (i = 0; i < num_listen_socks; i++) { 1104 if (!FD_ISSET(listen_socks[i], fdset)) 1105 continue; 1106 fromlen = sizeof(from); 1107 *newsock = accept(listen_socks[i], 1108 (struct sockaddr *)&from, &fromlen); 1109 if (*newsock < 0) { 1110 if (errno != EINTR && errno != EAGAIN && 1111 errno != EWOULDBLOCK) 1112 error("accept: %.100s", strerror(errno)); 1113 continue; 1114 } 1115 if (unset_nonblock(*newsock) == -1) { 1116 close(*newsock); 1117 continue; 1118 } 1119 if (drop_connection(startups) == 1) { 1120 debug("drop connection #%d", startups); 1121 close(*newsock); 1122 continue; 1123 } 1124 if (pipe(startup_p) == -1) { 1125 close(*newsock); 1126 continue; 1127 } 1128 1129 if (rexec_flag && socketpair(AF_UNIX, 1130 SOCK_STREAM, 0, config_s) == -1) { 1131 error("reexec socketpair: %s", 1132 strerror(errno)); 1133 close(*newsock); 1134 close(startup_p[0]); 1135 close(startup_p[1]); 1136 continue; 1137 } 1138 1139 for (j = 0; j < options.max_startups; j++) 1140 if (startup_pipes[j] == -1) { 1141 startup_pipes[j] = startup_p[0]; 1142 if (maxfd < startup_p[0]) 1143 maxfd = startup_p[0]; 1144 startups++; 1145 break; 1146 } 1147 1148 /* 1149 * Got connection. Fork a child to handle it, unless 1150 * we are in debugging mode. 1151 */ 1152 if (debug_flag) { 1153 /* 1154 * In debugging mode. Close the listening 1155 * socket, and start processing the 1156 * connection without forking. 1157 */ 1158 debug("Server will not fork when running in debugging mode."); 1159 close_listen_socks(); 1160 *sock_in = *newsock; 1161 *sock_out = *newsock; 1162 close(startup_p[0]); 1163 close(startup_p[1]); 1164 startup_pipe = -1; 1165 pid = getpid(); 1166 if (rexec_flag) { 1167 send_rexec_state(config_s[0], 1168 &cfg); 1169 close(config_s[0]); 1170 } 1171 break; 1172 } 1173 1174 /* 1175 * Normal production daemon. Fork, and have 1176 * the child process the connection. The 1177 * parent continues listening. 1178 */ 1179 platform_pre_fork(); 1180 if ((pid = fork()) == 0) { 1181 /* 1182 * Child. Close the listening and 1183 * max_startup sockets. Start using 1184 * the accepted socket. Reinitialize 1185 * logging (since our pid has changed). 1186 * We break out of the loop to handle 1187 * the connection. 1188 */ 1189 platform_post_fork_child(); 1190 startup_pipe = startup_p[1]; 1191 close_startup_pipes(); 1192 close_listen_socks(); 1193 *sock_in = *newsock; 1194 *sock_out = *newsock; 1195 log_init(__progname, 1196 options.log_level, 1197 options.log_facility, 1198 log_stderr); 1199 if (rexec_flag) 1200 close(config_s[0]); 1201 break; 1202 } 1203 1204 /* Parent. Stay in the loop. */ 1205 platform_post_fork_parent(pid); 1206 if (pid < 0) 1207 error("fork: %.100s", strerror(errno)); 1208 else 1209 debug("Forked child %ld.", (long)pid); 1210 1211 close(startup_p[1]); 1212 1213 if (rexec_flag) { 1214 send_rexec_state(config_s[0], &cfg); 1215 close(config_s[0]); 1216 close(config_s[1]); 1217 } 1218 1219 /* 1220 * Mark that the key has been used (it 1221 * was "given" to the child). 1222 */ 1223 if ((options.protocol & SSH_PROTO_1) && 1224 key_used == 0) { 1225 /* Schedule server key regeneration alarm. */ 1226 signal(SIGALRM, key_regeneration_alarm); 1227 alarm(options.key_regeneration_time); 1228 key_used = 1; 1229 } 1230 1231 close(*newsock); 1232 1233 /* 1234 * Ensure that our random state differs 1235 * from that of the child 1236 */ 1237 arc4random_stir(); 1238 } 1239 1240 /* child process check (or debug mode) */ 1241 if (num_listen_socks < 0) 1242 break; 1243 } 1244 } 1245 1246 1247 /* 1248 * Main program for the daemon. 1249 */ 1250 int 1251 main(int ac, char **av) 1252 { 1253 extern char *optarg; 1254 extern int optind; 1255 int opt, i, on = 1; 1256 int sock_in = -1, sock_out = -1, newsock = -1; 1257 const char *remote_ip; 1258 char *test_user = NULL, *test_host = NULL, *test_addr = NULL; 1259 int remote_port; 1260 char *line, *p, *cp; 1261 int config_s[2] = { -1 , -1 }; 1262 u_int64_t ibytes, obytes; 1263 mode_t new_umask; 1264 Key *key; 1265 Authctxt *authctxt; 1266 1267 #ifdef HAVE_SECUREWARE 1268 (void)set_auth_parameters(ac, av); 1269 #endif 1270 __progname = ssh_get_progname(av[0]); 1271 init_rng(); 1272 1273 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1274 saved_argc = ac; 1275 rexec_argc = ac; 1276 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1277 for (i = 0; i < ac; i++) 1278 saved_argv[i] = xstrdup(av[i]); 1279 saved_argv[i] = NULL; 1280 1281 #ifndef HAVE_SETPROCTITLE 1282 /* Prepare for later setproctitle emulation */ 1283 compat_init_setproctitle(ac, av); 1284 av = saved_argv; 1285 #endif 1286 1287 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1288 debug("setgroups(): %.200s", strerror(errno)); 1289 1290 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1291 sanitise_stdfd(); 1292 1293 /* Initialize configuration options to their default values. */ 1294 initialize_server_options(&options); 1295 1296 /* Avoid killing the process in high-pressure swapping environments. */ 1297 if (madvise(NULL, 0, MADV_PROTECT) != 0) 1298 debug("madvise(): %.200s", strerror(errno)); 1299 1300 /* Parse command-line arguments. */ 1301 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) { 1302 switch (opt) { 1303 case '4': 1304 options.address_family = AF_INET; 1305 break; 1306 case '6': 1307 options.address_family = AF_INET6; 1308 break; 1309 case 'f': 1310 config_file_name = optarg; 1311 break; 1312 case 'd': 1313 if (debug_flag == 0) { 1314 debug_flag = 1; 1315 options.log_level = SYSLOG_LEVEL_DEBUG1; 1316 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1317 options.log_level++; 1318 break; 1319 case 'D': 1320 no_daemon_flag = 1; 1321 break; 1322 case 'e': 1323 log_stderr = 1; 1324 break; 1325 case 'i': 1326 inetd_flag = 1; 1327 break; 1328 case 'r': 1329 rexec_flag = 0; 1330 break; 1331 case 'R': 1332 rexeced_flag = 1; 1333 inetd_flag = 1; 1334 break; 1335 case 'Q': 1336 /* ignored */ 1337 break; 1338 case 'q': 1339 options.log_level = SYSLOG_LEVEL_QUIET; 1340 break; 1341 case 'b': 1342 options.server_key_bits = (int)strtonum(optarg, 256, 1343 32768, NULL); 1344 break; 1345 case 'p': 1346 options.ports_from_cmdline = 1; 1347 if (options.num_ports >= MAX_PORTS) { 1348 fprintf(stderr, "too many ports.\n"); 1349 exit(1); 1350 } 1351 options.ports[options.num_ports++] = a2port(optarg); 1352 if (options.ports[options.num_ports-1] <= 0) { 1353 fprintf(stderr, "Bad port number.\n"); 1354 exit(1); 1355 } 1356 break; 1357 case 'g': 1358 if ((options.login_grace_time = convtime(optarg)) == -1) { 1359 fprintf(stderr, "Invalid login grace time.\n"); 1360 exit(1); 1361 } 1362 break; 1363 case 'k': 1364 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1365 fprintf(stderr, "Invalid key regeneration interval.\n"); 1366 exit(1); 1367 } 1368 break; 1369 case 'h': 1370 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1371 fprintf(stderr, "too many host keys.\n"); 1372 exit(1); 1373 } 1374 options.host_key_files[options.num_host_key_files++] = optarg; 1375 break; 1376 case 't': 1377 test_flag = 1; 1378 break; 1379 case 'T': 1380 test_flag = 2; 1381 break; 1382 case 'C': 1383 cp = optarg; 1384 while ((p = strsep(&cp, ",")) && *p != '\0') { 1385 if (strncmp(p, "addr=", 5) == 0) 1386 test_addr = xstrdup(p + 5); 1387 else if (strncmp(p, "host=", 5) == 0) 1388 test_host = xstrdup(p + 5); 1389 else if (strncmp(p, "user=", 5) == 0) 1390 test_user = xstrdup(p + 5); 1391 else { 1392 fprintf(stderr, "Invalid test " 1393 "mode specification %s\n", p); 1394 exit(1); 1395 } 1396 } 1397 break; 1398 case 'u': 1399 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1400 if (utmp_len > MAXHOSTNAMELEN) { 1401 fprintf(stderr, "Invalid utmp length.\n"); 1402 exit(1); 1403 } 1404 break; 1405 case 'o': 1406 line = xstrdup(optarg); 1407 if (process_server_config_line(&options, line, 1408 "command-line", 0, NULL, NULL, NULL, NULL) != 0) 1409 exit(1); 1410 xfree(line); 1411 break; 1412 case '?': 1413 default: 1414 usage(); 1415 break; 1416 } 1417 } 1418 if (rexeced_flag || inetd_flag) 1419 rexec_flag = 0; 1420 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1421 fatal("sshd re-exec requires execution with an absolute path"); 1422 if (rexeced_flag) 1423 closefrom(REEXEC_MIN_FREE_FD); 1424 else 1425 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1426 1427 SSLeay_add_all_algorithms(); 1428 1429 /* 1430 * Force logging to stderr until we have loaded the private host 1431 * key (unless started from inetd) 1432 */ 1433 log_init(__progname, 1434 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1435 SYSLOG_LEVEL_INFO : options.log_level, 1436 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1437 SYSLOG_FACILITY_AUTH : options.log_facility, 1438 log_stderr || !inetd_flag); 1439 1440 /* 1441 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1442 * root's environment 1443 */ 1444 if (getenv("KRB5CCNAME") != NULL) 1445 unsetenv("KRB5CCNAME"); 1446 1447 #ifdef _UNICOS 1448 /* Cray can define user privs drop all privs now! 1449 * Not needed on PRIV_SU systems! 1450 */ 1451 drop_cray_privs(); 1452 #endif 1453 1454 sensitive_data.server_key = NULL; 1455 sensitive_data.ssh1_host_key = NULL; 1456 sensitive_data.have_ssh1_key = 0; 1457 sensitive_data.have_ssh2_key = 0; 1458 1459 /* 1460 * If we're doing an extended config test, make sure we have all of 1461 * the parameters we need. If we're not doing an extended test, 1462 * do not silently ignore connection test params. 1463 */ 1464 if (test_flag >= 2 && 1465 (test_user != NULL || test_host != NULL || test_addr != NULL) 1466 && (test_user == NULL || test_host == NULL || test_addr == NULL)) 1467 fatal("user, host and addr are all required when testing " 1468 "Match configs"); 1469 if (test_flag < 2 && (test_user != NULL || test_host != NULL || 1470 test_addr != NULL)) 1471 fatal("Config test connection parameter (-C) provided without " 1472 "test mode (-T)"); 1473 1474 /* Fetch our configuration */ 1475 buffer_init(&cfg); 1476 if (rexeced_flag) 1477 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1478 else 1479 load_server_config(config_file_name, &cfg); 1480 1481 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1482 &cfg, NULL, NULL, NULL); 1483 1484 seed_rng(); 1485 1486 /* Fill in default values for those options not explicitly set. */ 1487 fill_default_server_options(&options); 1488 1489 /* challenge-response is implemented via keyboard interactive */ 1490 if (options.challenge_response_authentication) 1491 options.kbd_interactive_authentication = 1; 1492 1493 /* set default channel AF */ 1494 channel_set_af(options.address_family); 1495 1496 /* Check that there are no remaining arguments. */ 1497 if (optind < ac) { 1498 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1499 exit(1); 1500 } 1501 1502 debug("sshd version %.100s", SSH_RELEASE); 1503 1504 /* Store privilege separation user for later use if required. */ 1505 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1506 if (use_privsep || options.kerberos_authentication) 1507 fatal("Privilege separation user %s does not exist", 1508 SSH_PRIVSEP_USER); 1509 } else { 1510 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd)); 1511 privsep_pw = pwcopy(privsep_pw); 1512 xfree(privsep_pw->pw_passwd); 1513 privsep_pw->pw_passwd = xstrdup("*"); 1514 } 1515 endpwent(); 1516 1517 /* load private host keys */ 1518 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1519 sizeof(Key *)); 1520 for (i = 0; i < options.num_host_key_files; i++) 1521 sensitive_data.host_keys[i] = NULL; 1522 1523 for (i = 0; i < options.num_host_key_files; i++) { 1524 key = key_load_private(options.host_key_files[i], "", NULL); 1525 sensitive_data.host_keys[i] = key; 1526 if (key == NULL) { 1527 error("Could not load host key: %s", 1528 options.host_key_files[i]); 1529 sensitive_data.host_keys[i] = NULL; 1530 continue; 1531 } 1532 switch (key->type) { 1533 case KEY_RSA1: 1534 sensitive_data.ssh1_host_key = key; 1535 sensitive_data.have_ssh1_key = 1; 1536 break; 1537 case KEY_RSA: 1538 case KEY_DSA: 1539 sensitive_data.have_ssh2_key = 1; 1540 break; 1541 } 1542 debug("private host key: #%d type %d %s", i, key->type, 1543 key_type(key)); 1544 } 1545 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1546 logit("Disabling protocol version 1. Could not load host key"); 1547 options.protocol &= ~SSH_PROTO_1; 1548 } 1549 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1550 logit("Disabling protocol version 2. Could not load host key"); 1551 options.protocol &= ~SSH_PROTO_2; 1552 } 1553 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1554 logit("sshd: no hostkeys available -- exiting."); 1555 exit(1); 1556 } 1557 1558 /* Check certain values for sanity. */ 1559 if (options.protocol & SSH_PROTO_1) { 1560 if (options.server_key_bits < 512 || 1561 options.server_key_bits > 32768) { 1562 fprintf(stderr, "Bad server key size.\n"); 1563 exit(1); 1564 } 1565 /* 1566 * Check that server and host key lengths differ sufficiently. This 1567 * is necessary to make double encryption work with rsaref. Oh, I 1568 * hate software patents. I dont know if this can go? Niels 1569 */ 1570 if (options.server_key_bits > 1571 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1572 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1573 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1574 SSH_KEY_BITS_RESERVED) { 1575 options.server_key_bits = 1576 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1577 SSH_KEY_BITS_RESERVED; 1578 debug("Forcing server key to %d bits to make it differ from host key.", 1579 options.server_key_bits); 1580 } 1581 } 1582 1583 if (use_privsep) { 1584 struct stat st; 1585 1586 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1587 (S_ISDIR(st.st_mode) == 0)) 1588 fatal("Missing privilege separation directory: %s", 1589 _PATH_PRIVSEP_CHROOT_DIR); 1590 1591 #ifdef HAVE_CYGWIN 1592 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1593 (st.st_uid != getuid () || 1594 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1595 #else 1596 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1597 #endif 1598 fatal("%s must be owned by root and not group or " 1599 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1600 } 1601 1602 if (test_flag > 1) { 1603 if (test_user != NULL && test_addr != NULL && test_host != NULL) 1604 parse_server_match_config(&options, test_user, 1605 test_host, test_addr); 1606 dump_config(&options); 1607 } 1608 1609 /* Configuration looks good, so exit if in test mode. */ 1610 if (test_flag) 1611 exit(0); 1612 1613 /* 1614 * Clear out any supplemental groups we may have inherited. This 1615 * prevents inadvertent creation of files with bad modes (in the 1616 * portable version at least, it's certainly possible for PAM 1617 * to create a file, and we can't control the code in every 1618 * module which might be used). 1619 */ 1620 if (setgroups(0, NULL) < 0) 1621 debug("setgroups() failed: %.200s", strerror(errno)); 1622 1623 if (rexec_flag) { 1624 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1625 for (i = 0; i < rexec_argc; i++) { 1626 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1627 rexec_argv[i] = saved_argv[i]; 1628 } 1629 rexec_argv[rexec_argc] = "-R"; 1630 rexec_argv[rexec_argc + 1] = NULL; 1631 } 1632 1633 /* Ensure that umask disallows at least group and world write */ 1634 new_umask = umask(0077) | 0022; 1635 (void) umask(new_umask); 1636 1637 /* Initialize the log (it is reinitialized below in case we forked). */ 1638 if (debug_flag && (!inetd_flag || rexeced_flag)) 1639 log_stderr = 1; 1640 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1641 1642 /* 1643 * If not in debugging mode, and not started from inetd, disconnect 1644 * from the controlling terminal, and fork. The original process 1645 * exits. 1646 */ 1647 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1648 #ifdef TIOCNOTTY 1649 int fd; 1650 #endif /* TIOCNOTTY */ 1651 if (daemon(0, 0) < 0) 1652 fatal("daemon() failed: %.200s", strerror(errno)); 1653 1654 /* Disconnect from the controlling tty. */ 1655 #ifdef TIOCNOTTY 1656 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1657 if (fd >= 0) { 1658 (void) ioctl(fd, TIOCNOTTY, NULL); 1659 close(fd); 1660 } 1661 #endif /* TIOCNOTTY */ 1662 } 1663 /* Reinitialize the log (because of the fork above). */ 1664 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1665 1666 /* Initialize the random number generator. */ 1667 arc4random_stir(); 1668 1669 /* Chdir to the root directory so that the current disk can be 1670 unmounted if desired. */ 1671 chdir("/"); 1672 1673 /* ignore SIGPIPE */ 1674 signal(SIGPIPE, SIG_IGN); 1675 1676 /* Get a connection, either from inetd or a listening TCP socket */ 1677 if (inetd_flag) { 1678 server_accept_inetd(&sock_in, &sock_out); 1679 } else { 1680 server_listen(); 1681 1682 if (options.protocol & SSH_PROTO_1) 1683 generate_ephemeral_server_key(); 1684 1685 signal(SIGHUP, sighup_handler); 1686 signal(SIGCHLD, main_sigchld_handler); 1687 signal(SIGTERM, sigterm_handler); 1688 signal(SIGQUIT, sigterm_handler); 1689 1690 /* 1691 * Write out the pid file after the sigterm handler 1692 * is setup and the listen sockets are bound 1693 */ 1694 if (!debug_flag) { 1695 FILE *f = fopen(options.pid_file, "w"); 1696 1697 if (f == NULL) { 1698 error("Couldn't create pid file \"%s\": %s", 1699 options.pid_file, strerror(errno)); 1700 } else { 1701 fprintf(f, "%ld\n", (long) getpid()); 1702 fclose(f); 1703 } 1704 } 1705 1706 /* Accept a connection and return in a forked child */ 1707 server_accept_loop(&sock_in, &sock_out, 1708 &newsock, config_s); 1709 } 1710 1711 /* This is the child processing a new connection. */ 1712 setproctitle("%s", "[accepted]"); 1713 1714 /* 1715 * Create a new session and process group since the 4.4BSD 1716 * setlogin() affects the entire process group. We don't 1717 * want the child to be able to affect the parent. 1718 */ 1719 #if !defined(SSHD_ACQUIRES_CTTY) 1720 /* 1721 * If setsid is called, on some platforms sshd will later acquire a 1722 * controlling terminal which will result in "could not set 1723 * controlling tty" errors. 1724 */ 1725 if (!debug_flag && !inetd_flag && setsid() < 0) 1726 error("setsid: %.100s", strerror(errno)); 1727 #endif 1728 1729 if (rexec_flag) { 1730 int fd; 1731 1732 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1733 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1734 dup2(newsock, STDIN_FILENO); 1735 dup2(STDIN_FILENO, STDOUT_FILENO); 1736 if (startup_pipe == -1) 1737 close(REEXEC_STARTUP_PIPE_FD); 1738 else 1739 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1740 1741 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1742 close(config_s[1]); 1743 if (startup_pipe != -1) 1744 close(startup_pipe); 1745 1746 execv(rexec_argv[0], rexec_argv); 1747 1748 /* Reexec has failed, fall back and continue */ 1749 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1750 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1751 log_init(__progname, options.log_level, 1752 options.log_facility, log_stderr); 1753 1754 /* Clean up fds */ 1755 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1756 close(config_s[1]); 1757 close(REEXEC_CONFIG_PASS_FD); 1758 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1759 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1760 dup2(fd, STDIN_FILENO); 1761 dup2(fd, STDOUT_FILENO); 1762 if (fd > STDERR_FILENO) 1763 close(fd); 1764 } 1765 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1766 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1767 } 1768 1769 /* 1770 * Disable the key regeneration alarm. We will not regenerate the 1771 * key since we are no longer in a position to give it to anyone. We 1772 * will not restart on SIGHUP since it no longer makes sense. 1773 */ 1774 alarm(0); 1775 signal(SIGALRM, SIG_DFL); 1776 signal(SIGHUP, SIG_DFL); 1777 signal(SIGTERM, SIG_DFL); 1778 signal(SIGQUIT, SIG_DFL); 1779 signal(SIGCHLD, SIG_DFL); 1780 signal(SIGINT, SIG_DFL); 1781 1782 #ifdef __FreeBSD__ 1783 /* 1784 * Initialize the resolver. This may not happen automatically 1785 * before privsep chroot(). 1786 */ 1787 if ((_res.options & RES_INIT) == 0) { 1788 debug("res_init()"); 1789 res_init(); 1790 } 1791 #ifdef GSSAPI 1792 /* 1793 * Force GSS-API to parse its configuration and load any 1794 * mechanism plugins. 1795 */ 1796 { 1797 gss_OID_set mechs; 1798 OM_uint32 minor_status; 1799 gss_indicate_mechs(&minor_status, &mechs); 1800 gss_release_oid_set(&minor_status, &mechs); 1801 } 1802 #endif 1803 #endif 1804 1805 /* 1806 * Register our connection. This turns encryption off because we do 1807 * not have a key. 1808 */ 1809 packet_set_connection(sock_in, sock_out); 1810 packet_set_server(); 1811 1812 /* Set SO_KEEPALIVE if requested. */ 1813 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1814 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1815 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1816 1817 if ((remote_port = get_remote_port()) < 0) { 1818 debug("get_remote_port failed"); 1819 cleanup_exit(255); 1820 } 1821 1822 /* 1823 * We use get_canonical_hostname with usedns = 0 instead of 1824 * get_remote_ipaddr here so IP options will be checked. 1825 */ 1826 (void) get_canonical_hostname(0); 1827 /* 1828 * The rest of the code depends on the fact that 1829 * get_remote_ipaddr() caches the remote ip, even if 1830 * the socket goes away. 1831 */ 1832 remote_ip = get_remote_ipaddr(); 1833 1834 #ifdef SSH_AUDIT_EVENTS 1835 audit_connection_from(remote_ip, remote_port); 1836 #endif 1837 #ifdef LIBWRAP 1838 allow_severity = options.log_facility|LOG_INFO; 1839 deny_severity = options.log_facility|LOG_WARNING; 1840 /* Check whether logins are denied from this host. */ 1841 if (packet_connection_is_on_socket()) { 1842 struct request_info req; 1843 1844 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 1845 fromhost(&req); 1846 1847 if (!hosts_access(&req)) { 1848 debug("Connection refused by tcp wrapper"); 1849 refuse(&req); 1850 /* NOTREACHED */ 1851 fatal("libwrap refuse returns"); 1852 } 1853 } 1854 #endif /* LIBWRAP */ 1855 1856 /* Log the connection. */ 1857 verbose("Connection from %.500s port %d", remote_ip, remote_port); 1858 1859 /* 1860 * We don't want to listen forever unless the other side 1861 * successfully authenticates itself. So we set up an alarm which is 1862 * cleared after successful authentication. A limit of zero 1863 * indicates no limit. Note that we don't set the alarm in debugging 1864 * mode; it is just annoying to have the server exit just when you 1865 * are about to discover the bug. 1866 */ 1867 signal(SIGALRM, grace_alarm_handler); 1868 if (!debug_flag) 1869 alarm(options.login_grace_time); 1870 1871 sshd_exchange_identification(sock_in, sock_out); 1872 1873 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 1874 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 1875 generate_ephemeral_server_key(); 1876 1877 packet_set_nonblocking(); 1878 1879 /* allocate authentication context */ 1880 authctxt = xcalloc(1, sizeof(*authctxt)); 1881 1882 authctxt->loginmsg = &loginmsg; 1883 1884 /* XXX global for cleanup, access from other modules */ 1885 the_authctxt = authctxt; 1886 1887 /* prepare buffer to collect messages to display to user after login */ 1888 buffer_init(&loginmsg); 1889 1890 if (use_privsep) 1891 if (privsep_preauth(authctxt) == 1) 1892 goto authenticated; 1893 1894 /* perform the key exchange */ 1895 /* authenticate user and start session */ 1896 if (compat20) { 1897 do_ssh2_kex(); 1898 do_authentication2(authctxt); 1899 } else { 1900 do_ssh1_kex(); 1901 do_authentication(authctxt); 1902 } 1903 /* 1904 * If we use privilege separation, the unprivileged child transfers 1905 * the current keystate and exits 1906 */ 1907 if (use_privsep) { 1908 mm_send_keystate(pmonitor); 1909 exit(0); 1910 } 1911 1912 authenticated: 1913 /* 1914 * Cancel the alarm we set to limit the time taken for 1915 * authentication. 1916 */ 1917 alarm(0); 1918 signal(SIGALRM, SIG_DFL); 1919 authctxt->authenticated = 1; 1920 if (startup_pipe != -1) { 1921 close(startup_pipe); 1922 startup_pipe = -1; 1923 } 1924 1925 #ifdef SSH_AUDIT_EVENTS 1926 audit_event(SSH_AUTH_SUCCESS); 1927 #endif 1928 1929 #ifdef GSSAPI 1930 if (options.gss_authentication) { 1931 temporarily_use_uid(authctxt->pw); 1932 ssh_gssapi_storecreds(); 1933 restore_uid(); 1934 } 1935 #endif 1936 #ifdef USE_PAM 1937 if (options.use_pam) { 1938 do_pam_setcred(1); 1939 do_pam_session(); 1940 } 1941 #endif 1942 1943 /* 1944 * In privilege separation, we fork another child and prepare 1945 * file descriptor passing. 1946 */ 1947 if (use_privsep) { 1948 privsep_postauth(authctxt); 1949 /* the monitor process [priv] will not return */ 1950 if (!compat20) 1951 destroy_sensitive_data(); 1952 } 1953 1954 packet_set_timeout(options.client_alive_interval, 1955 options.client_alive_count_max); 1956 1957 /* Start session. */ 1958 do_authenticated(authctxt); 1959 1960 /* The connection has been terminated. */ 1961 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 1962 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 1963 verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes); 1964 1965 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 1966 1967 #ifdef USE_PAM 1968 if (options.use_pam) 1969 finish_pam(); 1970 #endif /* USE_PAM */ 1971 1972 #ifdef SSH_AUDIT_EVENTS 1973 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 1974 #endif 1975 1976 packet_close(); 1977 1978 if (use_privsep) 1979 mm_terminate(); 1980 1981 exit(0); 1982 } 1983 1984 /* 1985 * Decrypt session_key_int using our private server key and private host key 1986 * (key with larger modulus first). 1987 */ 1988 int 1989 ssh1_session_key(BIGNUM *session_key_int) 1990 { 1991 int rsafail = 0; 1992 1993 if (BN_cmp(sensitive_data.server_key->rsa->n, 1994 sensitive_data.ssh1_host_key->rsa->n) > 0) { 1995 /* Server key has bigger modulus. */ 1996 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 1997 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1998 SSH_KEY_BITS_RESERVED) { 1999 fatal("do_connection: %s: " 2000 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2001 get_remote_ipaddr(), 2002 BN_num_bits(sensitive_data.server_key->rsa->n), 2003 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2004 SSH_KEY_BITS_RESERVED); 2005 } 2006 if (rsa_private_decrypt(session_key_int, session_key_int, 2007 sensitive_data.server_key->rsa) <= 0) 2008 rsafail++; 2009 if (rsa_private_decrypt(session_key_int, session_key_int, 2010 sensitive_data.ssh1_host_key->rsa) <= 0) 2011 rsafail++; 2012 } else { 2013 /* Host key has bigger modulus (or they are equal). */ 2014 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2015 BN_num_bits(sensitive_data.server_key->rsa->n) + 2016 SSH_KEY_BITS_RESERVED) { 2017 fatal("do_connection: %s: " 2018 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2019 get_remote_ipaddr(), 2020 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2021 BN_num_bits(sensitive_data.server_key->rsa->n), 2022 SSH_KEY_BITS_RESERVED); 2023 } 2024 if (rsa_private_decrypt(session_key_int, session_key_int, 2025 sensitive_data.ssh1_host_key->rsa) < 0) 2026 rsafail++; 2027 if (rsa_private_decrypt(session_key_int, session_key_int, 2028 sensitive_data.server_key->rsa) < 0) 2029 rsafail++; 2030 } 2031 return (rsafail); 2032 } 2033 /* 2034 * SSH1 key exchange 2035 */ 2036 static void 2037 do_ssh1_kex(void) 2038 { 2039 int i, len; 2040 int rsafail = 0; 2041 BIGNUM *session_key_int; 2042 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2043 u_char cookie[8]; 2044 u_int cipher_type, auth_mask, protocol_flags; 2045 2046 /* 2047 * Generate check bytes that the client must send back in the user 2048 * packet in order for it to be accepted; this is used to defy ip 2049 * spoofing attacks. Note that this only works against somebody 2050 * doing IP spoofing from a remote machine; any machine on the local 2051 * network can still see outgoing packets and catch the random 2052 * cookie. This only affects rhosts authentication, and this is one 2053 * of the reasons why it is inherently insecure. 2054 */ 2055 arc4random_buf(cookie, sizeof(cookie)); 2056 2057 /* 2058 * Send our public key. We include in the packet 64 bits of random 2059 * data that must be matched in the reply in order to prevent IP 2060 * spoofing. 2061 */ 2062 packet_start(SSH_SMSG_PUBLIC_KEY); 2063 for (i = 0; i < 8; i++) 2064 packet_put_char(cookie[i]); 2065 2066 /* Store our public server RSA key. */ 2067 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2068 packet_put_bignum(sensitive_data.server_key->rsa->e); 2069 packet_put_bignum(sensitive_data.server_key->rsa->n); 2070 2071 /* Store our public host RSA key. */ 2072 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2073 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2074 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2075 2076 /* Put protocol flags. */ 2077 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2078 2079 /* Declare which ciphers we support. */ 2080 packet_put_int(cipher_mask_ssh1(0)); 2081 2082 /* Declare supported authentication types. */ 2083 auth_mask = 0; 2084 if (options.rhosts_rsa_authentication) 2085 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2086 if (options.rsa_authentication) 2087 auth_mask |= 1 << SSH_AUTH_RSA; 2088 if (options.challenge_response_authentication == 1) 2089 auth_mask |= 1 << SSH_AUTH_TIS; 2090 if (options.password_authentication) 2091 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2092 packet_put_int(auth_mask); 2093 2094 /* Send the packet and wait for it to be sent. */ 2095 packet_send(); 2096 packet_write_wait(); 2097 2098 debug("Sent %d bit server key and %d bit host key.", 2099 BN_num_bits(sensitive_data.server_key->rsa->n), 2100 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2101 2102 /* Read clients reply (cipher type and session key). */ 2103 packet_read_expect(SSH_CMSG_SESSION_KEY); 2104 2105 /* Get cipher type and check whether we accept this. */ 2106 cipher_type = packet_get_char(); 2107 2108 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2109 packet_disconnect("Warning: client selects unsupported cipher."); 2110 2111 /* Get check bytes from the packet. These must match those we 2112 sent earlier with the public key packet. */ 2113 for (i = 0; i < 8; i++) 2114 if (cookie[i] != packet_get_char()) 2115 packet_disconnect("IP Spoofing check bytes do not match."); 2116 2117 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2118 2119 /* Get the encrypted integer. */ 2120 if ((session_key_int = BN_new()) == NULL) 2121 fatal("do_ssh1_kex: BN_new failed"); 2122 packet_get_bignum(session_key_int); 2123 2124 protocol_flags = packet_get_int(); 2125 packet_set_protocol_flags(protocol_flags); 2126 packet_check_eom(); 2127 2128 /* Decrypt session_key_int using host/server keys */ 2129 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2130 2131 /* 2132 * Extract session key from the decrypted integer. The key is in the 2133 * least significant 256 bits of the integer; the first byte of the 2134 * key is in the highest bits. 2135 */ 2136 if (!rsafail) { 2137 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2138 len = BN_num_bytes(session_key_int); 2139 if (len < 0 || (u_int)len > sizeof(session_key)) { 2140 error("do_ssh1_kex: bad session key len from %s: " 2141 "session_key_int %d > sizeof(session_key) %lu", 2142 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2143 rsafail++; 2144 } else { 2145 memset(session_key, 0, sizeof(session_key)); 2146 BN_bn2bin(session_key_int, 2147 session_key + sizeof(session_key) - len); 2148 2149 derive_ssh1_session_id( 2150 sensitive_data.ssh1_host_key->rsa->n, 2151 sensitive_data.server_key->rsa->n, 2152 cookie, session_id); 2153 /* 2154 * Xor the first 16 bytes of the session key with the 2155 * session id. 2156 */ 2157 for (i = 0; i < 16; i++) 2158 session_key[i] ^= session_id[i]; 2159 } 2160 } 2161 if (rsafail) { 2162 int bytes = BN_num_bytes(session_key_int); 2163 u_char *buf = xmalloc(bytes); 2164 MD5_CTX md; 2165 2166 logit("do_connection: generating a fake encryption key"); 2167 BN_bn2bin(session_key_int, buf); 2168 MD5_Init(&md); 2169 MD5_Update(&md, buf, bytes); 2170 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2171 MD5_Final(session_key, &md); 2172 MD5_Init(&md); 2173 MD5_Update(&md, session_key, 16); 2174 MD5_Update(&md, buf, bytes); 2175 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2176 MD5_Final(session_key + 16, &md); 2177 memset(buf, 0, bytes); 2178 xfree(buf); 2179 for (i = 0; i < 16; i++) 2180 session_id[i] = session_key[i] ^ session_key[i + 16]; 2181 } 2182 /* Destroy the private and public keys. No longer. */ 2183 destroy_sensitive_data(); 2184 2185 if (use_privsep) 2186 mm_ssh1_session_id(session_id); 2187 2188 /* Destroy the decrypted integer. It is no longer needed. */ 2189 BN_clear_free(session_key_int); 2190 2191 /* Set the session key. From this on all communications will be encrypted. */ 2192 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2193 2194 /* Destroy our copy of the session key. It is no longer needed. */ 2195 memset(session_key, 0, sizeof(session_key)); 2196 2197 debug("Received session key; encryption turned on."); 2198 2199 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2200 packet_start(SSH_SMSG_SUCCESS); 2201 packet_send(); 2202 packet_write_wait(); 2203 } 2204 2205 /* 2206 * SSH2 key exchange: diffie-hellman-group1-sha1 2207 */ 2208 static void 2209 do_ssh2_kex(void) 2210 { 2211 Kex *kex; 2212 2213 if (options.ciphers != NULL) { 2214 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2215 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2216 } 2217 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2218 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2219 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2220 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2221 2222 if (options.macs != NULL) { 2223 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2224 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2225 } 2226 if (options.compression == COMP_NONE) { 2227 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2228 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2229 } else if (options.compression == COMP_DELAYED) { 2230 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2231 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2232 } 2233 2234 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); 2235 2236 /* start key exchange */ 2237 kex = kex_setup(myproposal); 2238 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2239 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2240 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2241 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2242 kex->server = 1; 2243 kex->client_version_string=client_version_string; 2244 kex->server_version_string=server_version_string; 2245 kex->load_host_key=&get_hostkey_by_type; 2246 kex->host_key_index=&get_hostkey_index; 2247 2248 xxx_kex = kex; 2249 2250 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2251 2252 session_id2 = kex->session_id; 2253 session_id2_len = kex->session_id_len; 2254 2255 #ifdef DEBUG_KEXDH 2256 /* send 1st encrypted/maced/compressed message */ 2257 packet_start(SSH2_MSG_IGNORE); 2258 packet_put_cstring("markus"); 2259 packet_send(); 2260 packet_write_wait(); 2261 #endif 2262 debug("KEX done"); 2263 } 2264 2265 /* server specific fatal cleanup */ 2266 void 2267 cleanup_exit(int i) 2268 { 2269 if (the_authctxt) 2270 do_cleanup(the_authctxt); 2271 #ifdef SSH_AUDIT_EVENTS 2272 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2273 if (!use_privsep || mm_is_monitor()) 2274 audit_event(SSH_CONNECTION_ABANDON); 2275 #endif 2276 _exit(i); 2277 } 2278