1 /* $NetBSD: sshd.c,v 1.8 2011/09/16 15:36:18 joerg Exp $ */ 2 /* $OpenBSD: sshd.c,v 1.385 2011/06/23 09:34:13 djm Exp $ */ 3 /* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * This program is the ssh daemon. It listens for connections from clients, 8 * and performs authentication, executes use commands or shell, and forwards 9 * information to/from the application to the user client over an encrypted 10 * connection. This can also handle forwarding of X11, TCP/IP, and 11 * authentication agent connections. 12 * 13 * As far as I am concerned, the code I have written for this software 14 * can be used freely for any purpose. Any derived versions of this 15 * software must be clearly marked as such, and if the derived work is 16 * incompatible with the protocol description in the RFC file, it must be 17 * called by a name other than "ssh" or "Secure Shell". 18 * 19 * SSH2 implementation: 20 * Privilege Separation: 21 * 22 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 23 * Copyright (c) 2002 Niels Provos. All rights reserved. 24 * 25 * Redistribution and use in source and binary forms, with or without 26 * modification, are permitted provided that the following conditions 27 * are met: 28 * 1. Redistributions of source code must retain the above copyright 29 * notice, this list of conditions and the following disclaimer. 30 * 2. Redistributions in binary form must reproduce the above copyright 31 * notice, this list of conditions and the following disclaimer in the 32 * documentation and/or other materials provided with the distribution. 33 * 34 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 35 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 36 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 37 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 38 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 39 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 40 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 41 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 42 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 43 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 44 */ 45 46 #include "includes.h" 47 __RCSID("$NetBSD: sshd.c,v 1.8 2011/09/16 15:36:18 joerg Exp $"); 48 #include <sys/types.h> 49 #include <sys/param.h> 50 #include <sys/ioctl.h> 51 #include <sys/wait.h> 52 #include <sys/tree.h> 53 #include <sys/stat.h> 54 #include <sys/socket.h> 55 #include <sys/time.h> 56 #include <sys/queue.h> 57 58 #include <errno.h> 59 #include <fcntl.h> 60 #include <netdb.h> 61 #include <paths.h> 62 #include <pwd.h> 63 #include <signal.h> 64 #include <stdio.h> 65 #include <stdlib.h> 66 #include <string.h> 67 #include <unistd.h> 68 69 #include <openssl/dh.h> 70 #include <openssl/bn.h> 71 #include <openssl/md5.h> 72 #include <openssl/rand.h> 73 74 #include "xmalloc.h" 75 #include "ssh.h" 76 #include "ssh1.h" 77 #include "ssh2.h" 78 #include "rsa.h" 79 #include "sshpty.h" 80 #include "packet.h" 81 #include "log.h" 82 #include "buffer.h" 83 #include "servconf.h" 84 #include "uidswap.h" 85 #include "compat.h" 86 #include "cipher.h" 87 #include "key.h" 88 #include "kex.h" 89 #include "dh.h" 90 #include "myproposal.h" 91 #include "authfile.h" 92 #include "pathnames.h" 93 #include "atomicio.h" 94 #include "canohost.h" 95 #include "hostfile.h" 96 #include "auth.h" 97 #include "misc.h" 98 #include "msg.h" 99 #include "dispatch.h" 100 #include "channels.h" 101 #include "session.h" 102 #include "monitor_mm.h" 103 #include "monitor.h" 104 #ifdef GSSAPI 105 #include "ssh-gss.h" 106 #endif 107 #include "monitor_wrap.h" 108 #include "roaming.h" 109 #include "ssh-sandbox.h" 110 #include "version.h" 111 #include "random.h" 112 113 #ifdef LIBWRAP 114 #include <tcpd.h> 115 #include <syslog.h> 116 int allow_severity = LOG_INFO; 117 int deny_severity = LOG_WARNING; 118 #endif /* LIBWRAP */ 119 120 #ifdef WITH_LDAP_PUBKEY 121 #include "ldapauth.h" 122 #endif 123 124 #ifndef O_NOCTTY 125 #define O_NOCTTY 0 126 #endif 127 128 /* Re-exec fds */ 129 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 130 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 131 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 132 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 133 134 int myflag = 0; 135 136 137 extern char *__progname; 138 139 /* Server configuration options. */ 140 ServerOptions options; 141 142 /* Name of the server configuration file. */ 143 const char *config_file_name = _PATH_SERVER_CONFIG_FILE; 144 145 /* 146 * Debug mode flag. This can be set on the command line. If debug 147 * mode is enabled, extra debugging output will be sent to the system 148 * log, the daemon will not go to background, and will exit after processing 149 * the first connection. 150 */ 151 int debug_flag = 0; 152 153 /* Flag indicating that the daemon should only test the configuration and keys. */ 154 int test_flag = 0; 155 156 /* Flag indicating that the daemon is being started from inetd. */ 157 int inetd_flag = 0; 158 159 /* Flag indicating that sshd should not detach and become a daemon. */ 160 int no_daemon_flag = 0; 161 162 /* debug goes to stderr unless inetd_flag is set */ 163 int log_stderr = 0; 164 165 /* Saved arguments to main(). */ 166 char **saved_argv; 167 168 /* re-exec */ 169 int rexeced_flag = 0; 170 int rexec_flag = 1; 171 int rexec_argc = 0; 172 char **rexec_argv; 173 174 /* 175 * The sockets that the server is listening; this is used in the SIGHUP 176 * signal handler. 177 */ 178 #define MAX_LISTEN_SOCKS 16 179 int listen_socks[MAX_LISTEN_SOCKS]; 180 int num_listen_socks = 0; 181 182 /* 183 * the client's version string, passed by sshd2 in compat mode. if != NULL, 184 * sshd will skip the version-number exchange 185 */ 186 char *client_version_string = NULL; 187 char *server_version_string = NULL; 188 189 /* for rekeying XXX fixme */ 190 Kex *xxx_kex; 191 192 /* 193 * Any really sensitive data in the application is contained in this 194 * structure. The idea is that this structure could be locked into memory so 195 * that the pages do not get written into swap. However, there are some 196 * problems. The private key contains BIGNUMs, and we do not (in principle) 197 * have access to the internals of them, and locking just the structure is 198 * not very useful. Currently, memory locking is not implemented. 199 */ 200 struct { 201 Key *server_key; /* ephemeral server key */ 202 Key *ssh1_host_key; /* ssh1 host key */ 203 Key **host_keys; /* all private host keys */ 204 Key **host_certificates; /* all public host certificates */ 205 int have_ssh1_key; 206 int have_ssh2_key; 207 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 208 } sensitive_data; 209 210 /* 211 * Flag indicating whether the RSA server key needs to be regenerated. 212 * Is set in the SIGALRM handler and cleared when the key is regenerated. 213 */ 214 static volatile sig_atomic_t key_do_regen = 0; 215 216 /* This is set to true when a signal is received. */ 217 static volatile sig_atomic_t received_sighup = 0; 218 static volatile sig_atomic_t received_sigterm = 0; 219 220 /* session identifier, used by RSA-auth */ 221 u_char session_id[16]; 222 223 /* same for ssh2 */ 224 u_char *session_id2 = NULL; 225 u_int session_id2_len = 0; 226 227 /* record remote hostname or ip */ 228 u_int utmp_len = MAXHOSTNAMELEN; 229 230 /* options.max_startup sized array of fd ints */ 231 int *startup_pipes = NULL; 232 int startup_pipe; /* in child */ 233 234 /* variables used for privilege separation */ 235 int use_privsep = -1; 236 struct monitor *pmonitor = NULL; 237 238 /* global authentication context */ 239 Authctxt *the_authctxt = NULL; 240 241 /* sshd_config buffer */ 242 Buffer cfg; 243 244 /* message to be displayed after login */ 245 Buffer loginmsg; 246 247 /* Prototypes for various functions defined later in this file. */ 248 void destroy_sensitive_data(void); 249 void demote_sensitive_data(void); 250 251 static void do_ssh1_kex(void); 252 static void do_ssh2_kex(void); 253 254 /* 255 * Close all listening sockets 256 */ 257 static void 258 close_listen_socks(void) 259 { 260 int i; 261 262 for (i = 0; i < num_listen_socks; i++) 263 close(listen_socks[i]); 264 num_listen_socks = -1; 265 } 266 267 static void 268 close_startup_pipes(void) 269 { 270 int i; 271 272 if (startup_pipes) 273 for (i = 0; i < options.max_startups; i++) 274 if (startup_pipes[i] != -1) 275 close(startup_pipes[i]); 276 } 277 278 /* 279 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 280 * the effect is to reread the configuration file (and to regenerate 281 * the server key). 282 */ 283 284 /*ARGSUSED*/ 285 static void 286 sighup_handler(int sig) 287 { 288 int save_errno = errno; 289 290 received_sighup = 1; 291 signal(SIGHUP, sighup_handler); 292 errno = save_errno; 293 } 294 295 /* 296 * Called from the main program after receiving SIGHUP. 297 * Restarts the server. 298 */ 299 __dead static void 300 sighup_restart(void) 301 { 302 logit("Received SIGHUP; restarting."); 303 close_listen_socks(); 304 close_startup_pipes(); 305 alarm(0); /* alarm timer persists across exec */ 306 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 307 execv(saved_argv[0], saved_argv); 308 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 309 strerror(errno)); 310 exit(1); 311 } 312 313 /* 314 * Generic signal handler for terminating signals in the master daemon. 315 */ 316 /*ARGSUSED*/ 317 static void 318 sigterm_handler(int sig) 319 { 320 received_sigterm = sig; 321 } 322 323 /* 324 * SIGCHLD handler. This is called whenever a child dies. This will then 325 * reap any zombies left by exited children. 326 */ 327 /*ARGSUSED*/ 328 static void 329 main_sigchld_handler(int sig) 330 { 331 int save_errno = errno; 332 pid_t pid; 333 int status; 334 335 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 336 (pid < 0 && errno == EINTR)) 337 ; 338 339 signal(SIGCHLD, main_sigchld_handler); 340 errno = save_errno; 341 } 342 343 /* 344 * Signal handler for the alarm after the login grace period has expired. 345 */ 346 /*ARGSUSED*/ 347 __dead static void 348 grace_alarm_handler(int sig) 349 { 350 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 351 kill(pmonitor->m_pid, SIGALRM); 352 353 /* Log error and exit. */ 354 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 355 } 356 357 /* 358 * Signal handler for the key regeneration alarm. Note that this 359 * alarm only occurs in the daemon waiting for connections, and it does not 360 * do anything with the private key or random state before forking. 361 * Thus there should be no concurrency control/asynchronous execution 362 * problems. 363 */ 364 static void 365 generate_ephemeral_server_key(void) 366 { 367 verbose("Generating %s%d bit RSA key.", 368 sensitive_data.server_key ? "new " : "", options.server_key_bits); 369 if (sensitive_data.server_key != NULL) 370 key_free(sensitive_data.server_key); 371 sensitive_data.server_key = key_generate(KEY_RSA1, 372 options.server_key_bits); 373 verbose("RSA key generation complete."); 374 375 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 376 arc4random_stir(); 377 } 378 379 /*ARGSUSED*/ 380 static void 381 key_regeneration_alarm(int sig) 382 { 383 int save_errno = errno; 384 385 signal(SIGALRM, SIG_DFL); 386 errno = save_errno; 387 key_do_regen = 1; 388 } 389 390 static void 391 sshd_exchange_identification(int sock_in, int sock_out) 392 { 393 u_int i; 394 int mismatch; 395 int remote_major, remote_minor; 396 int major, minor; 397 char *s; 398 const char *newline = "\n"; 399 char buf[256]; /* Must not be larger than remote_version. */ 400 char remote_version[256]; /* Must be at least as big as buf. */ 401 402 if ((options.protocol & SSH_PROTO_1) && 403 (options.protocol & SSH_PROTO_2)) { 404 major = PROTOCOL_MAJOR_1; 405 minor = 99; 406 } else if (options.protocol & SSH_PROTO_2) { 407 major = PROTOCOL_MAJOR_2; 408 minor = PROTOCOL_MINOR_2; 409 newline = "\r\n"; 410 } else { 411 major = PROTOCOL_MAJOR_1; 412 minor = PROTOCOL_MINOR_1; 413 } 414 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor, 415 SSH_RELEASE, newline); 416 server_version_string = xstrdup(buf); 417 418 /* Send our protocol version identification. */ 419 if (roaming_atomicio(vwrite, sock_out, server_version_string, 420 strlen(server_version_string)) 421 != strlen(server_version_string)) { 422 logit("Could not write ident string to %s", get_remote_ipaddr()); 423 cleanup_exit(255); 424 } 425 426 /* Read other sides version identification. */ 427 memset(buf, 0, sizeof(buf)); 428 for (i = 0; i < sizeof(buf) - 1; i++) { 429 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 430 logit("Did not receive identification string from %s", 431 get_remote_ipaddr()); 432 cleanup_exit(255); 433 } 434 if (buf[i] == '\r') { 435 buf[i] = 0; 436 /* Kludge for F-Secure Macintosh < 1.0.2 */ 437 if (i == 12 && 438 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 439 break; 440 continue; 441 } 442 if (buf[i] == '\n') { 443 buf[i] = 0; 444 break; 445 } 446 } 447 buf[sizeof(buf) - 1] = 0; 448 client_version_string = xstrdup(buf); 449 450 /* 451 * Check that the versions match. In future this might accept 452 * several versions and set appropriate flags to handle them. 453 */ 454 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 455 &remote_major, &remote_minor, remote_version) != 3) { 456 s = __UNCONST("Protocol mismatch.\n"); 457 (void) atomicio(vwrite, sock_out, s, strlen(s)); 458 close(sock_in); 459 close(sock_out); 460 logit("Bad protocol version identification '%.100s' from %s", 461 client_version_string, get_remote_ipaddr()); 462 cleanup_exit(255); 463 } 464 debug("Client protocol version %d.%d; client software version %.100s", 465 remote_major, remote_minor, remote_version); 466 logit("SSH: Server;Ltype: Version;Remote: %s-%d;Protocol: %d.%d;Client: %.100s", 467 get_remote_ipaddr(), get_remote_port(), 468 remote_major, remote_minor, remote_version); 469 470 compat_datafellows(remote_version); 471 472 if (datafellows & SSH_BUG_PROBE) { 473 logit("probed from %s with %s. Don't panic.", 474 get_remote_ipaddr(), client_version_string); 475 cleanup_exit(255); 476 } 477 478 if (datafellows & SSH_BUG_SCANNER) { 479 logit("scanned from %s with %s. Don't panic.", 480 get_remote_ipaddr(), client_version_string); 481 cleanup_exit(255); 482 } 483 484 mismatch = 0; 485 switch (remote_major) { 486 case 1: 487 if (remote_minor == 99) { 488 if (options.protocol & SSH_PROTO_2) 489 enable_compat20(); 490 else 491 mismatch = 1; 492 break; 493 } 494 if (!(options.protocol & SSH_PROTO_1)) { 495 mismatch = 1; 496 break; 497 } 498 if (remote_minor < 3) { 499 packet_disconnect("Your ssh version is too old and " 500 "is no longer supported. Please install a newer version."); 501 } else if (remote_minor == 3) { 502 /* note that this disables agent-forwarding */ 503 enable_compat13(); 504 } 505 break; 506 case 2: 507 if (options.protocol & SSH_PROTO_2) { 508 enable_compat20(); 509 break; 510 } 511 /* FALLTHROUGH */ 512 default: 513 mismatch = 1; 514 break; 515 } 516 chop(server_version_string); 517 debug("Local version string %.200s", server_version_string); 518 519 if (mismatch) { 520 s = __UNCONST("Protocol major versions differ.\n"); 521 (void) atomicio(vwrite, sock_out, s, strlen(s)); 522 close(sock_in); 523 close(sock_out); 524 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 525 get_remote_ipaddr(), 526 server_version_string, client_version_string); 527 cleanup_exit(255); 528 } 529 } 530 531 /* Destroy the host and server keys. They will no longer be needed. */ 532 void 533 destroy_sensitive_data(void) 534 { 535 int i; 536 537 if (sensitive_data.server_key) { 538 key_free(sensitive_data.server_key); 539 sensitive_data.server_key = NULL; 540 } 541 for (i = 0; i < options.num_host_key_files; i++) { 542 if (sensitive_data.host_keys[i]) { 543 key_free(sensitive_data.host_keys[i]); 544 sensitive_data.host_keys[i] = NULL; 545 } 546 if (sensitive_data.host_certificates[i]) { 547 key_free(sensitive_data.host_certificates[i]); 548 sensitive_data.host_certificates[i] = NULL; 549 } 550 } 551 sensitive_data.ssh1_host_key = NULL; 552 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); 553 } 554 555 /* Demote private to public keys for network child */ 556 void 557 demote_sensitive_data(void) 558 { 559 Key *tmp; 560 int i; 561 562 if (sensitive_data.server_key) { 563 tmp = key_demote(sensitive_data.server_key); 564 key_free(sensitive_data.server_key); 565 sensitive_data.server_key = tmp; 566 } 567 568 for (i = 0; i < options.num_host_key_files; i++) { 569 if (sensitive_data.host_keys[i]) { 570 tmp = key_demote(sensitive_data.host_keys[i]); 571 key_free(sensitive_data.host_keys[i]); 572 sensitive_data.host_keys[i] = tmp; 573 if (tmp->type == KEY_RSA1) 574 sensitive_data.ssh1_host_key = tmp; 575 } 576 /* Certs do not need demotion */ 577 } 578 579 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 580 } 581 582 static void 583 privsep_preauth_child(void) 584 { 585 u_int32_t rnd[256]; 586 gid_t gidset[1]; 587 struct passwd *pw; 588 589 /* Enable challenge-response authentication for privilege separation */ 590 privsep_challenge_enable(); 591 592 arc4random_stir(); 593 arc4random_buf(rnd, sizeof(rnd)); 594 RAND_seed(rnd, sizeof(rnd)); 595 596 /* Demote the private keys to public keys. */ 597 demote_sensitive_data(); 598 599 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) 600 fatal("Privilege separation user %s does not exist", 601 SSH_PRIVSEP_USER); 602 memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); 603 endpwent(); 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)pw->pw_uid, 614 (u_int)pw->pw_gid); 615 #if 0 616 /* XXX not ready, too heavy after chroot */ 617 do_setusercontext(pw); 618 #else 619 gidset[0] = pw->pw_gid; 620 if (setgroups(1, gidset) < 0) 621 fatal("setgroups: %.100s", strerror(errno)); 622 permanently_set_uid(pw); 623 #endif 624 } 625 626 static int 627 privsep_preauth(Authctxt *authctxt) 628 { 629 int status; 630 pid_t pid; 631 struct ssh_sandbox *box = NULL; 632 633 /* Set up unprivileged child process to deal with network data */ 634 pmonitor = monitor_init(); 635 /* Store a pointer to the kex for later rekeying */ 636 pmonitor->m_pkex = &xxx_kex; 637 638 if (use_privsep == PRIVSEP_SANDBOX) 639 box = ssh_sandbox_init(); 640 pid = fork(); 641 if (pid == -1) { 642 fatal("fork of unprivileged child failed"); 643 } else if (pid != 0) { 644 debug2("Network child is on pid %ld", (long)pid); 645 646 if (box != NULL) 647 ssh_sandbox_parent_preauth(box, pid); 648 pmonitor->m_pid = pid; 649 monitor_child_preauth(authctxt, pmonitor); 650 651 /* Sync memory */ 652 monitor_sync(pmonitor); 653 654 /* Wait for the child's exit status */ 655 while (waitpid(pid, &status, 0) < 0) { 656 if (errno != EINTR) 657 fatal("%s: waitpid: %s", __func__, 658 strerror(errno)); 659 } 660 if (WIFEXITED(status)) { 661 if (WEXITSTATUS(status) != 0) 662 fatal("%s: preauth child exited with status %d", 663 __func__, WEXITSTATUS(status)); 664 } else if (WIFSIGNALED(status)) 665 fatal("%s: preauth child terminated by signal %d", 666 __func__, WTERMSIG(status)); 667 if (box != NULL) 668 ssh_sandbox_parent_finish(box); 669 return 1; 670 } else { 671 /* child */ 672 close(pmonitor->m_sendfd); 673 close(pmonitor->m_log_recvfd); 674 675 /* Arrange for logging to be sent to the monitor */ 676 set_log_handler(mm_log_handler, pmonitor); 677 678 /* Demote the child */ 679 if (getuid() == 0 || geteuid() == 0) 680 privsep_preauth_child(); 681 setproctitle("%s", "[net]"); 682 if (box != NULL) 683 ssh_sandbox_child(box); 684 685 return 0; 686 } 687 } 688 689 static void 690 privsep_postauth(Authctxt *authctxt) 691 { 692 u_int32_t rnd[256]; 693 694 if (authctxt->pw->pw_uid == 0 || options.use_login) { 695 /* File descriptor passing is broken or root login */ 696 use_privsep = 0; 697 goto skip; 698 } 699 700 /* New socket pair */ 701 monitor_reinit(pmonitor); 702 703 pmonitor->m_pid = fork(); 704 if (pmonitor->m_pid == -1) 705 fatal("fork of unprivileged child failed"); 706 else if (pmonitor->m_pid != 0) { 707 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 708 buffer_clear(&loginmsg); 709 monitor_child_postauth(pmonitor); 710 711 /* NEVERREACHED */ 712 exit(0); 713 } 714 715 /* child */ 716 717 close(pmonitor->m_sendfd); 718 pmonitor->m_sendfd = -1; 719 720 /* Demote the private keys to public keys. */ 721 demote_sensitive_data(); 722 723 arc4random_stir(); 724 arc4random_buf(rnd, sizeof(rnd)); 725 RAND_seed(rnd, sizeof(rnd)); 726 727 /* Drop privileges */ 728 do_setusercontext(authctxt->pw); 729 730 skip: 731 /* It is safe now to apply the key state */ 732 monitor_apply_keystate(pmonitor); 733 734 /* 735 * Tell the packet layer that authentication was successful, since 736 * this information is not part of the key state. 737 */ 738 packet_set_authenticated(); 739 } 740 741 static char * 742 list_hostkey_types(void) 743 { 744 Buffer b; 745 const char *p; 746 char *ret; 747 int i; 748 Key *key; 749 750 buffer_init(&b); 751 for (i = 0; i < options.num_host_key_files; i++) { 752 key = sensitive_data.host_keys[i]; 753 if (key == NULL) 754 continue; 755 switch (key->type) { 756 case KEY_RSA: 757 case KEY_DSA: 758 case KEY_ECDSA: 759 if (buffer_len(&b) > 0) 760 buffer_append(&b, ",", 1); 761 p = key_ssh_name(key); 762 buffer_append(&b, p, strlen(p)); 763 break; 764 } 765 /* If the private key has a cert peer, then list that too */ 766 key = sensitive_data.host_certificates[i]; 767 if (key == NULL) 768 continue; 769 switch (key->type) { 770 case KEY_RSA_CERT_V00: 771 case KEY_DSA_CERT_V00: 772 case KEY_RSA_CERT: 773 case KEY_DSA_CERT: 774 case KEY_ECDSA_CERT: 775 if (buffer_len(&b) > 0) 776 buffer_append(&b, ",", 1); 777 p = key_ssh_name(key); 778 buffer_append(&b, p, strlen(p)); 779 break; 780 } 781 } 782 buffer_append(&b, "\0", 1); 783 ret = xstrdup(buffer_ptr(&b)); 784 buffer_free(&b); 785 debug("list_hostkey_types: %s", ret); 786 return ret; 787 } 788 789 static Key * 790 get_hostkey_by_type(int type, int need_private) 791 { 792 int i; 793 Key *key; 794 795 for (i = 0; i < options.num_host_key_files; i++) { 796 switch (type) { 797 case KEY_RSA_CERT_V00: 798 case KEY_DSA_CERT_V00: 799 case KEY_RSA_CERT: 800 case KEY_DSA_CERT: 801 case KEY_ECDSA_CERT: 802 key = sensitive_data.host_certificates[i]; 803 break; 804 default: 805 key = sensitive_data.host_keys[i]; 806 break; 807 } 808 if (key != NULL && key->type == type) 809 return need_private ? 810 sensitive_data.host_keys[i] : key; 811 } 812 return NULL; 813 } 814 815 Key * 816 get_hostkey_public_by_type(int type) 817 { 818 return get_hostkey_by_type(type, 0); 819 } 820 821 Key * 822 get_hostkey_private_by_type(int type) 823 { 824 return get_hostkey_by_type(type, 1); 825 } 826 827 Key * 828 get_hostkey_by_index(int ind) 829 { 830 if (ind < 0 || ind >= options.num_host_key_files) 831 return (NULL); 832 return (sensitive_data.host_keys[ind]); 833 } 834 835 int 836 get_hostkey_index(Key *key) 837 { 838 int i; 839 840 for (i = 0; i < options.num_host_key_files; i++) { 841 if (key_is_cert(key)) { 842 if (key == sensitive_data.host_certificates[i]) 843 return (i); 844 } else { 845 if (key == sensitive_data.host_keys[i]) 846 return (i); 847 } 848 } 849 return (-1); 850 } 851 852 /* 853 * returns 1 if connection should be dropped, 0 otherwise. 854 * dropping starts at connection #max_startups_begin with a probability 855 * of (max_startups_rate/100). the probability increases linearly until 856 * all connections are dropped for startups > max_startups 857 */ 858 static int 859 drop_connection(int startups) 860 { 861 int p, r; 862 863 if (startups < options.max_startups_begin) 864 return 0; 865 if (startups >= options.max_startups) 866 return 1; 867 if (options.max_startups_rate == 100) 868 return 1; 869 870 p = 100 - options.max_startups_rate; 871 p *= startups - options.max_startups_begin; 872 p /= options.max_startups - options.max_startups_begin; 873 p += options.max_startups_rate; 874 r = arc4random_uniform(100); 875 876 debug("drop_connection: p %d, r %d", p, r); 877 return (r < p) ? 1 : 0; 878 } 879 880 __dead static void 881 usage(void) 882 { 883 fprintf(stderr, "%s, %s\n", 884 SSH_VERSION, SSLeay_version(SSLEAY_VERSION)); 885 fprintf(stderr, 886 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 887 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n" 888 " [-k key_gen_time] [-o option] [-p port] [-u len]\n" 889 ); 890 exit(1); 891 } 892 893 static void 894 send_rexec_state(int fd, Buffer *conf) 895 { 896 Buffer m; 897 898 debug3("%s: entering fd = %d config len %d", __func__, fd, 899 buffer_len(conf)); 900 901 /* 902 * Protocol from reexec master to child: 903 * string configuration 904 * u_int ephemeral_key_follows 905 * bignum e (only if ephemeral_key_follows == 1) 906 * bignum n " 907 * bignum d " 908 * bignum iqmp " 909 * bignum p " 910 * bignum q " 911 */ 912 buffer_init(&m); 913 buffer_put_cstring(&m, buffer_ptr(conf)); 914 915 if (sensitive_data.server_key != NULL && 916 sensitive_data.server_key->type == KEY_RSA1) { 917 buffer_put_int(&m, 1); 918 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 919 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 920 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 921 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 922 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 923 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 924 } else 925 buffer_put_int(&m, 0); 926 927 if (ssh_msg_send(fd, 0, &m) == -1) 928 fatal("%s: ssh_msg_send failed", __func__); 929 930 buffer_free(&m); 931 932 debug3("%s: done", __func__); 933 } 934 935 static void 936 recv_rexec_state(int fd, Buffer *conf) 937 { 938 Buffer m; 939 char *cp; 940 u_int len; 941 942 debug3("%s: entering fd = %d", __func__, fd); 943 944 buffer_init(&m); 945 946 if (ssh_msg_recv(fd, &m) == -1) 947 fatal("%s: ssh_msg_recv failed", __func__); 948 if (buffer_get_char(&m) != 0) 949 fatal("%s: rexec version mismatch", __func__); 950 951 cp = buffer_get_string(&m, &len); 952 if (conf != NULL) 953 buffer_append(conf, cp, len + 1); 954 xfree(cp); 955 956 if (buffer_get_int(&m)) { 957 if (sensitive_data.server_key != NULL) 958 key_free(sensitive_data.server_key); 959 sensitive_data.server_key = key_new_private(KEY_RSA1); 960 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 961 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 962 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 963 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 964 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 965 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 966 rsa_generate_additional_parameters( 967 sensitive_data.server_key->rsa); 968 } 969 buffer_free(&m); 970 971 debug3("%s: done", __func__); 972 } 973 974 /* Accept a connection from inetd */ 975 static void 976 server_accept_inetd(int *sock_in, int *sock_out) 977 { 978 int fd; 979 980 startup_pipe = -1; 981 if (rexeced_flag) { 982 close(REEXEC_CONFIG_PASS_FD); 983 *sock_in = *sock_out = dup(STDIN_FILENO); 984 if (!debug_flag) { 985 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 986 close(REEXEC_STARTUP_PIPE_FD); 987 } 988 } else { 989 *sock_in = dup(STDIN_FILENO); 990 *sock_out = dup(STDOUT_FILENO); 991 } 992 /* 993 * We intentionally do not close the descriptors 0, 1, and 2 994 * as our code for setting the descriptors won't work if 995 * ttyfd happens to be one of those. 996 */ 997 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 998 dup2(fd, STDIN_FILENO); 999 dup2(fd, STDOUT_FILENO); 1000 if (fd > STDOUT_FILENO) 1001 close(fd); 1002 } 1003 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1004 } 1005 1006 /* 1007 * Listen for TCP connections 1008 */ 1009 static void 1010 server_listen(void) 1011 { 1012 int ret, listen_sock, on = 1; 1013 struct addrinfo *ai; 1014 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1015 int socksize; 1016 socklen_t socksizelen = sizeof(int); 1017 1018 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1019 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1020 continue; 1021 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1022 fatal("Too many listen sockets. " 1023 "Enlarge MAX_LISTEN_SOCKS"); 1024 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1025 ntop, sizeof(ntop), strport, sizeof(strport), 1026 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1027 error("getnameinfo failed: %.100s", 1028 ssh_gai_strerror(ret)); 1029 continue; 1030 } 1031 /* Create socket for listening. */ 1032 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1033 ai->ai_protocol); 1034 if (listen_sock < 0) { 1035 /* kernel may not support ipv6 */ 1036 verbose("socket: %.100s", strerror(errno)); 1037 continue; 1038 } 1039 if (set_nonblock(listen_sock) == -1) { 1040 close(listen_sock); 1041 continue; 1042 } 1043 /* 1044 * Set socket options. 1045 * Allow local port reuse in TIME_WAIT. 1046 */ 1047 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1048 &on, sizeof(on)) == -1) 1049 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1050 1051 debug("Bind to port %s on %s.", strport, ntop); 1052 1053 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, 1054 &socksize, &socksizelen); 1055 debug("Server TCP RWIN socket size: %d", socksize); 1056 debug("HPN Buffer Size: %d", options.hpn_buffer_size); 1057 1058 /* Bind the socket to the desired port. */ 1059 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1060 error("Bind to port %s on %s failed: %.200s.", 1061 strport, ntop, strerror(errno)); 1062 close(listen_sock); 1063 continue; 1064 } 1065 listen_socks[num_listen_socks] = listen_sock; 1066 num_listen_socks++; 1067 1068 /* Start listening on the port. */ 1069 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1070 fatal("listen on [%s]:%s: %.100s", 1071 ntop, strport, strerror(errno)); 1072 logit("Server listening on %s port %s.", ntop, strport); 1073 } 1074 freeaddrinfo(options.listen_addrs); 1075 1076 if (!num_listen_socks) 1077 fatal("Cannot bind any address."); 1078 } 1079 1080 /* 1081 * The main TCP accept loop. Note that, for the non-debug case, returns 1082 * from this function are in a forked subprocess. 1083 */ 1084 static void 1085 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1086 { 1087 fd_set *fdset; 1088 int i, j, ret, maxfd; 1089 int key_used = 0, startups = 0; 1090 int startup_p[2] = { -1 , -1 }; 1091 struct sockaddr_storage from; 1092 socklen_t fromlen; 1093 pid_t pid; 1094 1095 /* setup fd set for accept */ 1096 fdset = NULL; 1097 maxfd = 0; 1098 for (i = 0; i < num_listen_socks; i++) 1099 if (listen_socks[i] > maxfd) 1100 maxfd = listen_socks[i]; 1101 /* pipes connected to unauthenticated childs */ 1102 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1103 for (i = 0; i < options.max_startups; i++) 1104 startup_pipes[i] = -1; 1105 1106 /* 1107 * Stay listening for connections until the system crashes or 1108 * the daemon is killed with a signal. 1109 */ 1110 for (;;) { 1111 if (received_sighup) 1112 sighup_restart(); 1113 if (fdset != NULL) 1114 xfree(fdset); 1115 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1116 sizeof(fd_mask)); 1117 1118 for (i = 0; i < num_listen_socks; i++) 1119 FD_SET(listen_socks[i], fdset); 1120 for (i = 0; i < options.max_startups; i++) 1121 if (startup_pipes[i] != -1) 1122 FD_SET(startup_pipes[i], fdset); 1123 1124 /* Wait in select until there is a connection. */ 1125 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1126 if (ret < 0 && errno != EINTR) 1127 error("select: %.100s", strerror(errno)); 1128 if (received_sigterm) { 1129 logit("Received signal %d; terminating.", 1130 (int) received_sigterm); 1131 close_listen_socks(); 1132 unlink(options.pid_file); 1133 exit(received_sigterm == SIGTERM ? 0 : 255); 1134 } 1135 if (key_used && key_do_regen) { 1136 generate_ephemeral_server_key(); 1137 key_used = 0; 1138 key_do_regen = 0; 1139 } 1140 if (ret < 0) 1141 continue; 1142 1143 for (i = 0; i < options.max_startups; i++) 1144 if (startup_pipes[i] != -1 && 1145 FD_ISSET(startup_pipes[i], fdset)) { 1146 /* 1147 * the read end of the pipe is ready 1148 * if the child has closed the pipe 1149 * after successful authentication 1150 * or if the child has died 1151 */ 1152 close(startup_pipes[i]); 1153 startup_pipes[i] = -1; 1154 startups--; 1155 } 1156 for (i = 0; i < num_listen_socks; i++) { 1157 if (!FD_ISSET(listen_socks[i], fdset)) 1158 continue; 1159 fromlen = sizeof(from); 1160 *newsock = accept(listen_socks[i], 1161 (struct sockaddr *)&from, &fromlen); 1162 if (*newsock < 0) { 1163 if (errno != EINTR && errno != EWOULDBLOCK) 1164 error("accept: %.100s", strerror(errno)); 1165 continue; 1166 } 1167 if (unset_nonblock(*newsock) == -1) { 1168 close(*newsock); 1169 continue; 1170 } 1171 if (drop_connection(startups) == 1) { 1172 debug("drop connection #%d", startups); 1173 close(*newsock); 1174 continue; 1175 } 1176 if (pipe(startup_p) == -1) { 1177 close(*newsock); 1178 continue; 1179 } 1180 1181 if (rexec_flag && socketpair(AF_UNIX, 1182 SOCK_STREAM, 0, config_s) == -1) { 1183 error("reexec socketpair: %s", 1184 strerror(errno)); 1185 close(*newsock); 1186 close(startup_p[0]); 1187 close(startup_p[1]); 1188 continue; 1189 } 1190 1191 for (j = 0; j < options.max_startups; j++) 1192 if (startup_pipes[j] == -1) { 1193 startup_pipes[j] = startup_p[0]; 1194 if (maxfd < startup_p[0]) 1195 maxfd = startup_p[0]; 1196 startups++; 1197 break; 1198 } 1199 1200 /* 1201 * Got connection. Fork a child to handle it, unless 1202 * we are in debugging mode. 1203 */ 1204 if (debug_flag) { 1205 /* 1206 * In debugging mode. Close the listening 1207 * socket, and start processing the 1208 * connection without forking. 1209 */ 1210 debug("Server will not fork when running in debugging mode."); 1211 close_listen_socks(); 1212 *sock_in = *newsock; 1213 *sock_out = *newsock; 1214 close(startup_p[0]); 1215 close(startup_p[1]); 1216 startup_pipe = -1; 1217 pid = getpid(); 1218 if (rexec_flag) { 1219 send_rexec_state(config_s[0], 1220 &cfg); 1221 close(config_s[0]); 1222 } 1223 break; 1224 } 1225 1226 /* 1227 * Normal production daemon. Fork, and have 1228 * the child process the connection. The 1229 * parent continues listening. 1230 */ 1231 if ((pid = fork()) == 0) { 1232 /* 1233 * Child. Close the listening and 1234 * max_startup sockets. Start using 1235 * the accepted socket. Reinitialize 1236 * logging (since our pid has changed). 1237 * We break out of the loop to handle 1238 * the connection. 1239 */ 1240 startup_pipe = startup_p[1]; 1241 close_startup_pipes(); 1242 close_listen_socks(); 1243 *sock_in = *newsock; 1244 *sock_out = *newsock; 1245 log_init(__progname, 1246 options.log_level, 1247 options.log_facility, 1248 log_stderr); 1249 if (rexec_flag) 1250 close(config_s[0]); 1251 break; 1252 } 1253 1254 /* Parent. Stay in the loop. */ 1255 if (pid < 0) 1256 error("fork: %.100s", strerror(errno)); 1257 else 1258 debug("Forked child %ld.", (long)pid); 1259 1260 close(startup_p[1]); 1261 1262 if (rexec_flag) { 1263 send_rexec_state(config_s[0], &cfg); 1264 close(config_s[0]); 1265 close(config_s[1]); 1266 } 1267 1268 /* 1269 * Mark that the key has been used (it 1270 * was "given" to the child). 1271 */ 1272 if ((options.protocol & SSH_PROTO_1) && 1273 key_used == 0) { 1274 /* Schedule server key regeneration alarm. */ 1275 signal(SIGALRM, key_regeneration_alarm); 1276 alarm(options.key_regeneration_time); 1277 key_used = 1; 1278 } 1279 1280 close(*newsock); 1281 1282 /* 1283 * Ensure that our random state differs 1284 * from that of the child 1285 */ 1286 arc4random_stir(); 1287 } 1288 1289 /* child process check (or debug mode) */ 1290 if (num_listen_socks < 0) 1291 break; 1292 } 1293 } 1294 1295 1296 /* 1297 * Main program for the daemon. 1298 */ 1299 int 1300 main(int ac, char **av) 1301 { 1302 extern char *optarg; 1303 extern int optind; 1304 int opt, i, j, on = 1; 1305 int sock_in = -1, sock_out = -1, newsock = -1; 1306 const char *remote_ip; 1307 char *test_user = NULL, *test_host = NULL, *test_addr = NULL; 1308 int remote_port; 1309 char *line, *p, *cp; 1310 int config_s[2] = { -1 , -1 }; 1311 u_int64_t ibytes, obytes; 1312 mode_t new_umask; 1313 Key *key; 1314 Authctxt *authctxt; 1315 1316 /* Save argv. */ 1317 saved_argv = av; 1318 rexec_argc = ac; 1319 1320 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1321 sanitise_stdfd(); 1322 1323 /* Initialize configuration options to their default values. */ 1324 initialize_server_options(&options); 1325 1326 /* Parse command-line arguments. */ 1327 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) { 1328 switch (opt) { 1329 case '4': 1330 options.address_family = AF_INET; 1331 break; 1332 case '6': 1333 options.address_family = AF_INET6; 1334 break; 1335 case 'f': 1336 config_file_name = optarg; 1337 break; 1338 case 'c': 1339 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1340 fprintf(stderr, "too many host certificates.\n"); 1341 exit(1); 1342 } 1343 options.host_cert_files[options.num_host_cert_files++] = 1344 derelativise_path(optarg); 1345 break; 1346 case 'd': 1347 if (debug_flag == 0) { 1348 debug_flag = 1; 1349 options.log_level = SYSLOG_LEVEL_DEBUG1; 1350 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1351 options.log_level++; 1352 break; 1353 case 'D': 1354 no_daemon_flag = 1; 1355 break; 1356 case 'e': 1357 log_stderr = 1; 1358 break; 1359 case 'i': 1360 inetd_flag = 1; 1361 break; 1362 case 'r': 1363 rexec_flag = 0; 1364 break; 1365 case 'R': 1366 rexeced_flag = 1; 1367 inetd_flag = 1; 1368 break; 1369 case 'Q': 1370 /* ignored */ 1371 break; 1372 case 'q': 1373 options.log_level = SYSLOG_LEVEL_QUIET; 1374 break; 1375 case 'b': 1376 options.server_key_bits = (int)strtonum(optarg, 256, 1377 32768, NULL); 1378 break; 1379 case 'p': 1380 options.ports_from_cmdline = 1; 1381 if (options.num_ports >= MAX_PORTS) { 1382 fprintf(stderr, "too many ports.\n"); 1383 exit(1); 1384 } 1385 options.ports[options.num_ports++] = a2port(optarg); 1386 if (options.ports[options.num_ports-1] <= 0) { 1387 fprintf(stderr, "Bad port number.\n"); 1388 exit(1); 1389 } 1390 break; 1391 case 'g': 1392 if ((options.login_grace_time = convtime(optarg)) == -1) { 1393 fprintf(stderr, "Invalid login grace time.\n"); 1394 exit(1); 1395 } 1396 break; 1397 case 'k': 1398 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1399 fprintf(stderr, "Invalid key regeneration interval.\n"); 1400 exit(1); 1401 } 1402 break; 1403 case 'h': 1404 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1405 fprintf(stderr, "too many host keys.\n"); 1406 exit(1); 1407 } 1408 options.host_key_files[options.num_host_key_files++] = 1409 derelativise_path(optarg); 1410 break; 1411 case 't': 1412 test_flag = 1; 1413 break; 1414 case 'T': 1415 test_flag = 2; 1416 break; 1417 case 'C': 1418 cp = optarg; 1419 while ((p = strsep(&cp, ",")) && *p != '\0') { 1420 if (strncmp(p, "addr=", 5) == 0) 1421 test_addr = xstrdup(p + 5); 1422 else if (strncmp(p, "host=", 5) == 0) 1423 test_host = xstrdup(p + 5); 1424 else if (strncmp(p, "user=", 5) == 0) 1425 test_user = xstrdup(p + 5); 1426 else { 1427 fprintf(stderr, "Invalid test " 1428 "mode specification %s\n", p); 1429 exit(1); 1430 } 1431 } 1432 break; 1433 case 'u': 1434 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1435 if (utmp_len > MAXHOSTNAMELEN) { 1436 fprintf(stderr, "Invalid utmp length.\n"); 1437 exit(1); 1438 } 1439 break; 1440 case 'o': 1441 line = xstrdup(optarg); 1442 if (process_server_config_line(&options, line, 1443 "command-line", 0, NULL, NULL, NULL, NULL) != 0) 1444 exit(1); 1445 xfree(line); 1446 break; 1447 case '?': 1448 default: 1449 usage(); 1450 break; 1451 } 1452 } 1453 if (rexeced_flag || inetd_flag) 1454 rexec_flag = 0; 1455 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1456 fatal("sshd re-exec requires execution with an absolute path"); 1457 if (rexeced_flag) 1458 closefrom(REEXEC_MIN_FREE_FD); 1459 else 1460 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1461 1462 OpenSSL_add_all_algorithms(); 1463 1464 /* 1465 * Force logging to stderr until we have loaded the private host 1466 * key (unless started from inetd) 1467 */ 1468 log_init(__progname, 1469 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1470 SYSLOG_LEVEL_INFO : options.log_level, 1471 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1472 SYSLOG_FACILITY_AUTH : options.log_facility, 1473 log_stderr || !inetd_flag); 1474 1475 sensitive_data.server_key = NULL; 1476 sensitive_data.ssh1_host_key = NULL; 1477 sensitive_data.have_ssh1_key = 0; 1478 sensitive_data.have_ssh2_key = 0; 1479 1480 /* 1481 * If we're doing an extended config test, make sure we have all of 1482 * the parameters we need. If we're not doing an extended test, 1483 * do not silently ignore connection test params. 1484 */ 1485 if (test_flag >= 2 && 1486 (test_user != NULL || test_host != NULL || test_addr != NULL) 1487 && (test_user == NULL || test_host == NULL || test_addr == NULL)) 1488 fatal("user, host and addr are all required when testing " 1489 "Match configs"); 1490 if (test_flag < 2 && (test_user != NULL || test_host != NULL || 1491 test_addr != NULL)) 1492 fatal("Config test connection parameter (-C) provided without " 1493 "test mode (-T)"); 1494 1495 /* Fetch our configuration */ 1496 buffer_init(&cfg); 1497 if (rexeced_flag) 1498 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1499 else 1500 load_server_config(config_file_name, &cfg); 1501 1502 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1503 &cfg, NULL, NULL, NULL); 1504 1505 /* Fill in default values for those options not explicitly set. */ 1506 fill_default_server_options(&options); 1507 1508 /* challenge-response is implemented via keyboard interactive */ 1509 if (options.challenge_response_authentication) 1510 options.kbd_interactive_authentication = 1; 1511 1512 /* set default channel AF */ 1513 channel_set_af(options.address_family); 1514 1515 /* Check that there are no remaining arguments. */ 1516 if (optind < ac) { 1517 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1518 exit(1); 1519 } 1520 1521 #ifdef WITH_LDAP_PUBKEY 1522 /* ldap_options_print(&options.lpk); */ 1523 /* XXX initialize/check ldap connection and set *LD */ 1524 if (options.lpk.on) { 1525 if (options.lpk.l_conf && (ldap_parse_lconf(&options.lpk) < 0) ) 1526 error("[LDAP] could not parse %s", options.lpk.l_conf); 1527 if (ldap_connect(&options.lpk) < 0) 1528 error("[LDAP] could not initialize ldap connection"); 1529 } 1530 #endif 1531 debug("sshd version %.100s", SSH_VERSION); 1532 1533 /* load private host keys */ 1534 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1535 sizeof(Key *)); 1536 for (i = 0; i < options.num_host_key_files; i++) 1537 sensitive_data.host_keys[i] = NULL; 1538 1539 for (i = 0; i < options.num_host_key_files; i++) { 1540 key = key_load_private(options.host_key_files[i], "", NULL); 1541 sensitive_data.host_keys[i] = key; 1542 if (key == NULL) { 1543 error("Could not load host key: %s", 1544 options.host_key_files[i]); 1545 sensitive_data.host_keys[i] = NULL; 1546 continue; 1547 } 1548 switch (key->type) { 1549 case KEY_RSA1: 1550 sensitive_data.ssh1_host_key = key; 1551 sensitive_data.have_ssh1_key = 1; 1552 break; 1553 case KEY_RSA: 1554 case KEY_DSA: 1555 case KEY_ECDSA: 1556 sensitive_data.have_ssh2_key = 1; 1557 break; 1558 } 1559 debug("private host key: #%d type %d %s", i, key->type, 1560 key_type(key)); 1561 } 1562 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1563 logit("Disabling protocol version 1. Could not load host key"); 1564 options.protocol &= ~SSH_PROTO_1; 1565 } 1566 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1567 logit("Disabling protocol version 2. Could not load host key"); 1568 options.protocol &= ~SSH_PROTO_2; 1569 } 1570 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1571 logit("sshd: no hostkeys available -- exiting."); 1572 exit(1); 1573 } 1574 1575 /* 1576 * Load certificates. They are stored in an array at identical 1577 * indices to the public keys that they relate to. 1578 */ 1579 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1580 sizeof(Key *)); 1581 for (i = 0; i < options.num_host_key_files; i++) 1582 sensitive_data.host_certificates[i] = NULL; 1583 1584 for (i = 0; i < options.num_host_cert_files; i++) { 1585 key = key_load_public(options.host_cert_files[i], NULL); 1586 if (key == NULL) { 1587 error("Could not load host certificate: %s", 1588 options.host_cert_files[i]); 1589 continue; 1590 } 1591 if (!key_is_cert(key)) { 1592 error("Certificate file is not a certificate: %s", 1593 options.host_cert_files[i]); 1594 key_free(key); 1595 continue; 1596 } 1597 /* Find matching private key */ 1598 for (j = 0; j < options.num_host_key_files; j++) { 1599 if (key_equal_public(key, 1600 sensitive_data.host_keys[j])) { 1601 sensitive_data.host_certificates[j] = key; 1602 break; 1603 } 1604 } 1605 if (j >= options.num_host_key_files) { 1606 error("No matching private key for certificate: %s", 1607 options.host_cert_files[i]); 1608 key_free(key); 1609 continue; 1610 } 1611 sensitive_data.host_certificates[j] = key; 1612 debug("host certificate: #%d type %d %s", j, key->type, 1613 key_type(key)); 1614 } 1615 /* Check certain values for sanity. */ 1616 if (options.protocol & SSH_PROTO_1) { 1617 if (options.server_key_bits < 512 || 1618 options.server_key_bits > 32768) { 1619 fprintf(stderr, "Bad server key size.\n"); 1620 exit(1); 1621 } 1622 /* 1623 * Check that server and host key lengths differ sufficiently. This 1624 * is necessary to make double encryption work with rsaref. Oh, I 1625 * hate software patents. I dont know if this can go? Niels 1626 */ 1627 if (options.server_key_bits > 1628 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1629 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1630 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1631 SSH_KEY_BITS_RESERVED) { 1632 options.server_key_bits = 1633 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1634 SSH_KEY_BITS_RESERVED; 1635 debug("Forcing server key to %d bits to make it differ from host key.", 1636 options.server_key_bits); 1637 } 1638 } 1639 1640 if (use_privsep) { 1641 struct stat st; 1642 1643 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1644 fatal("Privilege separation user %s does not exist", 1645 SSH_PRIVSEP_USER); 1646 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1647 (S_ISDIR(st.st_mode) == 0)) 1648 fatal("Missing privilege separation directory: %s", 1649 _PATH_PRIVSEP_CHROOT_DIR); 1650 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1651 fatal("%s must be owned by root and not group or " 1652 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1653 } 1654 1655 if (test_flag > 1) { 1656 if (test_user != NULL && test_addr != NULL && test_host != NULL) 1657 parse_server_match_config(&options, test_user, 1658 test_host, test_addr); 1659 dump_config(&options); 1660 } 1661 1662 /* Configuration looks good, so exit if in test mode. */ 1663 if (test_flag) 1664 exit(0); 1665 1666 if (rexec_flag) { 1667 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1668 for (i = 0; i < rexec_argc; i++) { 1669 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1670 rexec_argv[i] = saved_argv[i]; 1671 } 1672 rexec_argv[rexec_argc] = __UNCONST("-R"); 1673 rexec_argv[rexec_argc + 1] = NULL; 1674 } 1675 1676 /* Ensure that umask disallows at least group and world write */ 1677 new_umask = umask(0077) | 0022; 1678 (void) umask(new_umask); 1679 1680 /* Initialize the log (it is reinitialized below in case we forked). */ 1681 if (debug_flag && (!inetd_flag || rexeced_flag)) 1682 log_stderr = 1; 1683 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1684 1685 /* 1686 * If not in debugging mode, and not started from inetd, disconnect 1687 * from the controlling terminal, and fork. The original process 1688 * exits. 1689 */ 1690 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1691 int fd; 1692 1693 if (daemon(0, 0) < 0) 1694 fatal("daemon() failed: %.200s", strerror(errno)); 1695 1696 /* Disconnect from the controlling tty. */ 1697 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1698 if (fd >= 0) { 1699 (void) ioctl(fd, TIOCNOTTY, NULL); 1700 close(fd); 1701 } 1702 } 1703 /* Reinitialize the log (because of the fork above). */ 1704 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1705 1706 /* Initialize the random number generator. */ 1707 arc4random_stir(); 1708 1709 /* Chdir to the root directory so that the current disk can be 1710 unmounted if desired. */ 1711 chdir("/"); 1712 1713 /* ignore SIGPIPE */ 1714 signal(SIGPIPE, SIG_IGN); 1715 1716 /* Get a connection, either from inetd or a listening TCP socket */ 1717 if (inetd_flag) { 1718 server_accept_inetd(&sock_in, &sock_out); 1719 } else { 1720 server_listen(); 1721 1722 if (options.protocol & SSH_PROTO_1) 1723 generate_ephemeral_server_key(); 1724 1725 signal(SIGHUP, sighup_handler); 1726 signal(SIGCHLD, main_sigchld_handler); 1727 signal(SIGTERM, sigterm_handler); 1728 signal(SIGQUIT, sigterm_handler); 1729 1730 /* 1731 * Write out the pid file after the sigterm handler 1732 * is setup and the listen sockets are bound 1733 */ 1734 if (!debug_flag) { 1735 FILE *f = fopen(options.pid_file, "w"); 1736 1737 if (f == NULL) { 1738 error("Couldn't create pid file \"%s\": %s", 1739 options.pid_file, strerror(errno)); 1740 } else { 1741 fprintf(f, "%ld\n", (long) getpid()); 1742 fclose(f); 1743 } 1744 } 1745 1746 /* Accept a connection and return in a forked child */ 1747 server_accept_loop(&sock_in, &sock_out, 1748 &newsock, config_s); 1749 } 1750 1751 /* This is the child processing a new connection. */ 1752 setproctitle("%s", "[accepted]"); 1753 1754 /* 1755 * Create a new session and process group since the 4.4BSD 1756 * setlogin() affects the entire process group. We don't 1757 * want the child to be able to affect the parent. 1758 */ 1759 if (!debug_flag && !inetd_flag && setsid() < 0) 1760 error("setsid: %.100s", strerror(errno)); 1761 1762 if (rexec_flag) { 1763 int fd; 1764 1765 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1766 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1767 dup2(newsock, STDIN_FILENO); 1768 dup2(STDIN_FILENO, STDOUT_FILENO); 1769 if (startup_pipe == -1) 1770 close(REEXEC_STARTUP_PIPE_FD); 1771 else 1772 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1773 1774 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1775 close(config_s[1]); 1776 if (startup_pipe != -1) 1777 close(startup_pipe); 1778 1779 execv(rexec_argv[0], rexec_argv); 1780 1781 /* Reexec has failed, fall back and continue */ 1782 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1783 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1784 log_init(__progname, options.log_level, 1785 options.log_facility, log_stderr); 1786 1787 /* Clean up fds */ 1788 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1789 close(config_s[1]); 1790 close(REEXEC_CONFIG_PASS_FD); 1791 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1792 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1793 dup2(fd, STDIN_FILENO); 1794 dup2(fd, STDOUT_FILENO); 1795 if (fd > STDERR_FILENO) 1796 close(fd); 1797 } 1798 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1799 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1800 } 1801 1802 /* Executed child processes don't need these. */ 1803 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1804 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1805 1806 /* 1807 * Disable the key regeneration alarm. We will not regenerate the 1808 * key since we are no longer in a position to give it to anyone. We 1809 * will not restart on SIGHUP since it no longer makes sense. 1810 */ 1811 alarm(0); 1812 signal(SIGALRM, SIG_DFL); 1813 signal(SIGHUP, SIG_DFL); 1814 signal(SIGTERM, SIG_DFL); 1815 signal(SIGQUIT, SIG_DFL); 1816 signal(SIGCHLD, SIG_DFL); 1817 1818 /* 1819 * Register our connection. This turns encryption off because we do 1820 * not have a key. 1821 */ 1822 packet_set_connection(sock_in, sock_out); 1823 packet_set_server(); 1824 1825 /* Set SO_KEEPALIVE if requested. */ 1826 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1827 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1828 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1829 1830 if ((remote_port = get_remote_port()) < 0) { 1831 debug("get_remote_port failed"); 1832 cleanup_exit(255); 1833 } 1834 1835 /* 1836 * We use get_canonical_hostname with usedns = 0 instead of 1837 * get_remote_ipaddr here so IP options will be checked. 1838 */ 1839 (void) get_canonical_hostname(0); 1840 /* 1841 * The rest of the code depends on the fact that 1842 * get_remote_ipaddr() caches the remote ip, even if 1843 * the socket goes away. 1844 */ 1845 remote_ip = get_remote_ipaddr(); 1846 1847 #ifdef LIBWRAP 1848 /* Check whether logins are denied from this host. */ 1849 if (packet_connection_is_on_socket()) { 1850 struct request_info req; 1851 1852 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 1853 fromhost(&req); 1854 1855 if (!hosts_access(&req)) { 1856 debug("Connection refused by tcp wrapper"); 1857 refuse(&req); 1858 /* NOTREACHED */ 1859 fatal("libwrap refuse returns"); 1860 } 1861 } 1862 #endif /* LIBWRAP */ 1863 1864 /* Log the connection. */ 1865 verbose("Connection from %.500s port %d", remote_ip, remote_port); 1866 1867 /* set the HPN options for the child */ 1868 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size); 1869 1870 /* 1871 * We don't want to listen forever unless the other side 1872 * successfully authenticates itself. So we set up an alarm which is 1873 * cleared after successful authentication. A limit of zero 1874 * indicates no limit. Note that we don't set the alarm in debugging 1875 * mode; it is just annoying to have the server exit just when you 1876 * are about to discover the bug. 1877 */ 1878 signal(SIGALRM, grace_alarm_handler); 1879 if (!debug_flag) 1880 alarm(options.login_grace_time); 1881 1882 sshd_exchange_identification(sock_in, sock_out); 1883 1884 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 1885 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 1886 generate_ephemeral_server_key(); 1887 1888 packet_set_nonblocking(); 1889 1890 /* allocate authentication context */ 1891 authctxt = xcalloc(1, sizeof(*authctxt)); 1892 1893 /* XXX global for cleanup, access from other modules */ 1894 the_authctxt = authctxt; 1895 1896 /* prepare buffer to collect messages to display to user after login */ 1897 buffer_init(&loginmsg); 1898 auth_debug_reset(); 1899 1900 if (use_privsep) 1901 if (privsep_preauth(authctxt) == 1) 1902 goto authenticated; 1903 1904 /* perform the key exchange */ 1905 /* authenticate user and start session */ 1906 if (compat20) { 1907 do_ssh2_kex(); 1908 do_authentication2(authctxt); 1909 } else { 1910 do_ssh1_kex(); 1911 do_authentication(authctxt); 1912 } 1913 /* 1914 * If we use privilege separation, the unprivileged child transfers 1915 * the current keystate and exits 1916 */ 1917 if (use_privsep) { 1918 mm_send_keystate(pmonitor); 1919 exit(0); 1920 } 1921 1922 authenticated: 1923 /* 1924 * Cancel the alarm we set to limit the time taken for 1925 * authentication. 1926 */ 1927 alarm(0); 1928 signal(SIGALRM, SIG_DFL); 1929 authctxt->authenticated = 1; 1930 if (startup_pipe != -1) { 1931 close(startup_pipe); 1932 startup_pipe = -1; 1933 } 1934 1935 #ifdef USE_PAM 1936 if (options.use_pam) { 1937 do_pam_setcred(1); 1938 do_pam_session(); 1939 } 1940 #endif 1941 1942 /* 1943 * In privilege separation, we fork another child and prepare 1944 * file descriptor passing. 1945 */ 1946 if (use_privsep) { 1947 privsep_postauth(authctxt); 1948 /* the monitor process [priv] will not return */ 1949 if (!compat20) 1950 destroy_sensitive_data(); 1951 } 1952 1953 packet_set_timeout(options.client_alive_interval, 1954 options.client_alive_count_max); 1955 1956 /* Start session. */ 1957 do_authenticated(authctxt); 1958 1959 #ifdef USE_PAM 1960 if (options.use_pam) 1961 finish_pam(); 1962 #endif /* USE_PAM */ 1963 1964 /* The connection has been terminated. */ 1965 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 1966 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 1967 verbose("Transferred: sent %llu, received %llu bytes", 1968 (unsigned long long)obytes, (unsigned long long)ibytes); 1969 1970 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 1971 packet_close(); 1972 1973 if (use_privsep) 1974 mm_terminate(); 1975 1976 exit(0); 1977 } 1978 1979 /* 1980 * Decrypt session_key_int using our private server key and private host key 1981 * (key with larger modulus first). 1982 */ 1983 int 1984 ssh1_session_key(BIGNUM *session_key_int) 1985 { 1986 int rsafail = 0; 1987 1988 if (BN_cmp(sensitive_data.server_key->rsa->n, 1989 sensitive_data.ssh1_host_key->rsa->n) > 0) { 1990 /* Server key has bigger modulus. */ 1991 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 1992 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1993 SSH_KEY_BITS_RESERVED) { 1994 fatal("do_connection: %s: " 1995 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 1996 get_remote_ipaddr(), 1997 BN_num_bits(sensitive_data.server_key->rsa->n), 1998 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 1999 SSH_KEY_BITS_RESERVED); 2000 } 2001 if (rsa_private_decrypt(session_key_int, session_key_int, 2002 sensitive_data.server_key->rsa) <= 0) 2003 rsafail++; 2004 if (rsa_private_decrypt(session_key_int, session_key_int, 2005 sensitive_data.ssh1_host_key->rsa) <= 0) 2006 rsafail++; 2007 } else { 2008 /* Host key has bigger modulus (or they are equal). */ 2009 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2010 BN_num_bits(sensitive_data.server_key->rsa->n) + 2011 SSH_KEY_BITS_RESERVED) { 2012 fatal("do_connection: %s: " 2013 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2014 get_remote_ipaddr(), 2015 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2016 BN_num_bits(sensitive_data.server_key->rsa->n), 2017 SSH_KEY_BITS_RESERVED); 2018 } 2019 if (rsa_private_decrypt(session_key_int, session_key_int, 2020 sensitive_data.ssh1_host_key->rsa) < 0) 2021 rsafail++; 2022 if (rsa_private_decrypt(session_key_int, session_key_int, 2023 sensitive_data.server_key->rsa) < 0) 2024 rsafail++; 2025 } 2026 return (rsafail); 2027 } 2028 /* 2029 * SSH1 key exchange 2030 */ 2031 static void 2032 do_ssh1_kex(void) 2033 { 2034 int i, len; 2035 int rsafail = 0; 2036 BIGNUM *session_key_int; 2037 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2038 u_char cookie[8]; 2039 u_int cipher_type, auth_mask, protocol_flags; 2040 2041 /* 2042 * Generate check bytes that the client must send back in the user 2043 * packet in order for it to be accepted; this is used to defy ip 2044 * spoofing attacks. Note that this only works against somebody 2045 * doing IP spoofing from a remote machine; any machine on the local 2046 * network can still see outgoing packets and catch the random 2047 * cookie. This only affects rhosts authentication, and this is one 2048 * of the reasons why it is inherently insecure. 2049 */ 2050 arc4random_buf(cookie, sizeof(cookie)); 2051 2052 /* 2053 * Send our public key. We include in the packet 64 bits of random 2054 * data that must be matched in the reply in order to prevent IP 2055 * spoofing. 2056 */ 2057 packet_start(SSH_SMSG_PUBLIC_KEY); 2058 for (i = 0; i < 8; i++) 2059 packet_put_char(cookie[i]); 2060 2061 /* Store our public server RSA key. */ 2062 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2063 packet_put_bignum(sensitive_data.server_key->rsa->e); 2064 packet_put_bignum(sensitive_data.server_key->rsa->n); 2065 2066 /* Store our public host RSA key. */ 2067 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2068 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2069 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2070 2071 /* Put protocol flags. */ 2072 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2073 2074 /* Declare which ciphers we support. */ 2075 packet_put_int(cipher_mask_ssh1(0)); 2076 2077 /* Declare supported authentication types. */ 2078 auth_mask = 0; 2079 if (options.rhosts_rsa_authentication) 2080 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2081 if (options.rsa_authentication) 2082 auth_mask |= 1 << SSH_AUTH_RSA; 2083 #if defined(KRB4) || defined(KRB5) 2084 if (options.kerberos_authentication) 2085 auth_mask |= 1 << SSH_AUTH_KERBEROS; 2086 #endif 2087 #if defined(AFS) || defined(KRB5) 2088 if (options.kerberos_tgt_passing) 2089 auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; 2090 #endif 2091 #ifdef AFS 2092 if (options.afs_token_passing) 2093 auth_mask |= 1 << SSH_PASS_AFS_TOKEN; 2094 #endif 2095 if (options.challenge_response_authentication == 1) 2096 auth_mask |= 1 << SSH_AUTH_TIS; 2097 if (options.password_authentication) 2098 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2099 packet_put_int(auth_mask); 2100 2101 /* Send the packet and wait for it to be sent. */ 2102 packet_send(); 2103 packet_write_wait(); 2104 2105 debug("Sent %d bit server key and %d bit host key.", 2106 BN_num_bits(sensitive_data.server_key->rsa->n), 2107 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2108 2109 /* Read clients reply (cipher type and session key). */ 2110 packet_read_expect(SSH_CMSG_SESSION_KEY); 2111 2112 /* Get cipher type and check whether we accept this. */ 2113 cipher_type = packet_get_char(); 2114 2115 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2116 packet_disconnect("Warning: client selects unsupported cipher."); 2117 2118 /* Get check bytes from the packet. These must match those we 2119 sent earlier with the public key packet. */ 2120 for (i = 0; i < 8; i++) 2121 if (cookie[i] != packet_get_char()) 2122 packet_disconnect("IP Spoofing check bytes do not match."); 2123 2124 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2125 2126 /* Get the encrypted integer. */ 2127 if ((session_key_int = BN_new()) == NULL) 2128 fatal("do_ssh1_kex: BN_new failed"); 2129 packet_get_bignum(session_key_int); 2130 2131 protocol_flags = packet_get_int(); 2132 packet_set_protocol_flags(protocol_flags); 2133 packet_check_eom(); 2134 2135 /* Decrypt session_key_int using host/server keys */ 2136 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2137 2138 /* 2139 * Extract session key from the decrypted integer. The key is in the 2140 * least significant 256 bits of the integer; the first byte of the 2141 * key is in the highest bits. 2142 */ 2143 if (!rsafail) { 2144 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2145 len = BN_num_bytes(session_key_int); 2146 if (len < 0 || (u_int)len > sizeof(session_key)) { 2147 error("do_ssh1_kex: bad session key len from %s: " 2148 "session_key_int %d > sizeof(session_key) %lu", 2149 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2150 rsafail++; 2151 } else { 2152 memset(session_key, 0, sizeof(session_key)); 2153 BN_bn2bin(session_key_int, 2154 session_key + sizeof(session_key) - len); 2155 2156 derive_ssh1_session_id( 2157 sensitive_data.ssh1_host_key->rsa->n, 2158 sensitive_data.server_key->rsa->n, 2159 cookie, session_id); 2160 /* 2161 * Xor the first 16 bytes of the session key with the 2162 * session id. 2163 */ 2164 for (i = 0; i < 16; i++) 2165 session_key[i] ^= session_id[i]; 2166 } 2167 } 2168 if (rsafail) { 2169 int bytes = BN_num_bytes(session_key_int); 2170 u_char *buf = xmalloc(bytes); 2171 MD5_CTX md; 2172 2173 logit("do_connection: generating a fake encryption key"); 2174 BN_bn2bin(session_key_int, buf); 2175 MD5_Init(&md); 2176 MD5_Update(&md, buf, bytes); 2177 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2178 MD5_Final(session_key, &md); 2179 MD5_Init(&md); 2180 MD5_Update(&md, session_key, 16); 2181 MD5_Update(&md, buf, bytes); 2182 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2183 MD5_Final(session_key + 16, &md); 2184 memset(buf, 0, bytes); 2185 xfree(buf); 2186 for (i = 0; i < 16; i++) 2187 session_id[i] = session_key[i] ^ session_key[i + 16]; 2188 } 2189 /* Destroy the private and public keys. No longer. */ 2190 destroy_sensitive_data(); 2191 2192 if (use_privsep) 2193 mm_ssh1_session_id(session_id); 2194 2195 /* Destroy the decrypted integer. It is no longer needed. */ 2196 BN_clear_free(session_key_int); 2197 2198 /* Set the session key. From this on all communications will be encrypted. */ 2199 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2200 2201 /* Destroy our copy of the session key. It is no longer needed. */ 2202 memset(session_key, 0, sizeof(session_key)); 2203 2204 debug("Received session key; encryption turned on."); 2205 2206 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2207 packet_start(SSH_SMSG_SUCCESS); 2208 packet_send(); 2209 packet_write_wait(); 2210 } 2211 2212 /* 2213 * SSH2 key exchange: diffie-hellman-group1-sha1 2214 */ 2215 static void 2216 do_ssh2_kex(void) 2217 { 2218 Kex *kex; 2219 2220 myflag++; 2221 debug ("MYFLAG IS %d", myflag); 2222 if (options.ciphers != NULL) { 2223 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2224 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2225 } else if (options.none_enabled == 1) { 2226 debug ("WARNING: None cipher enabled"); 2227 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2228 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE; 2229 } 2230 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2231 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2232 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2233 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2234 2235 if (options.macs != NULL) { 2236 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2237 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2238 } 2239 if (options.compression == COMP_NONE) { 2240 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2241 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2242 } else if (options.compression == COMP_DELAYED) { 2243 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2244 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2245 } 2246 if (options.kex_algorithms != NULL) 2247 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 2248 2249 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); 2250 2251 /* start key exchange */ 2252 kex = kex_setup(myproposal); 2253 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2254 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2255 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2256 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2257 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2258 kex->server = 1; 2259 kex->client_version_string=client_version_string; 2260 kex->server_version_string=server_version_string; 2261 kex->load_host_public_key=&get_hostkey_public_by_type; 2262 kex->load_host_private_key=&get_hostkey_private_by_type; 2263 kex->host_key_index=&get_hostkey_index; 2264 2265 xxx_kex = kex; 2266 2267 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2268 2269 session_id2 = kex->session_id; 2270 session_id2_len = kex->session_id_len; 2271 2272 #ifdef DEBUG_KEXDH 2273 /* send 1st encrypted/maced/compressed message */ 2274 packet_start(SSH2_MSG_IGNORE); 2275 packet_put_cstring("markus"); 2276 packet_send(); 2277 packet_write_wait(); 2278 #endif 2279 debug("KEX done"); 2280 } 2281 2282 /* server specific fatal cleanup */ 2283 void 2284 cleanup_exit(int i) 2285 { 2286 if (the_authctxt) 2287 do_cleanup(the_authctxt); 2288 _exit(i); 2289 } 2290