1 /* $OpenBSD: sshd.c,v 1.375 2010/04/16 01:47:26 djm 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 47 #include <sys/types.h> 48 #include <sys/ioctl.h> 49 #include <sys/socket.h> 50 #ifdef HAVE_SYS_STAT_H 51 # include <sys/stat.h> 52 #endif 53 #ifdef HAVE_SYS_TIME_H 54 # include <sys/time.h> 55 #endif 56 #include "openbsd-compat/sys-tree.h" 57 #include "openbsd-compat/sys-queue.h" 58 #include <sys/wait.h> 59 60 #include <errno.h> 61 #include <fcntl.h> 62 #include <netdb.h> 63 #ifdef HAVE_PATHS_H 64 #include <paths.h> 65 #endif 66 #include <grp.h> 67 #include <pwd.h> 68 #include <signal.h> 69 #include <stdarg.h> 70 #include <stdio.h> 71 #include <stdlib.h> 72 #include <string.h> 73 #include <unistd.h> 74 75 #include <openssl/dh.h> 76 #include <openssl/bn.h> 77 #include <openssl/md5.h> 78 #include <openssl/rand.h> 79 #include "openbsd-compat/openssl-compat.h" 80 81 #ifdef HAVE_SECUREWARE 82 #include <sys/security.h> 83 #include <prot.h> 84 #endif 85 86 #include <resolv.h> 87 #include "xmalloc.h" 88 #include "ssh.h" 89 #include "ssh1.h" 90 #include "ssh2.h" 91 #include "rsa.h" 92 #include "sshpty.h" 93 #include "packet.h" 94 #include "log.h" 95 #include "buffer.h" 96 #include "servconf.h" 97 #include "uidswap.h" 98 #include "compat.h" 99 #include "cipher.h" 100 #include "key.h" 101 #include "kex.h" 102 #include "dh.h" 103 #include "myproposal.h" 104 #include "authfile.h" 105 #include "pathnames.h" 106 #include "atomicio.h" 107 #include "canohost.h" 108 #include "hostfile.h" 109 #include "auth.h" 110 #include "misc.h" 111 #include "msg.h" 112 #include "dispatch.h" 113 #include "channels.h" 114 #include "session.h" 115 #include "monitor_mm.h" 116 #include "monitor.h" 117 #ifdef GSSAPI 118 #include "ssh-gss.h" 119 #endif 120 #include "monitor_wrap.h" 121 #include "roaming.h" 122 #include "version.h" 123 124 #ifdef LIBWRAP 125 #include <tcpd.h> 126 #include <syslog.h> 127 int allow_severity; 128 int deny_severity; 129 #endif /* LIBWRAP */ 130 131 #ifndef O_NOCTTY 132 #define O_NOCTTY 0 133 #endif 134 135 /* Re-exec fds */ 136 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 137 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 138 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 139 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 140 141 int myflag = 0; 142 143 144 extern char *__progname; 145 146 /* Server configuration options. */ 147 ServerOptions options; 148 149 /* Name of the server configuration file. */ 150 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 151 152 /* 153 * Debug mode flag. This can be set on the command line. If debug 154 * mode is enabled, extra debugging output will be sent to the system 155 * log, the daemon will not go to background, and will exit after processing 156 * the first connection. 157 */ 158 int debug_flag = 0; 159 160 /* Flag indicating that the daemon should only test the configuration and keys. */ 161 int test_flag = 0; 162 163 /* Flag indicating that the daemon is being started from inetd. */ 164 int inetd_flag = 0; 165 166 /* Flag indicating that sshd should not detach and become a daemon. */ 167 int no_daemon_flag = 0; 168 169 /* debug goes to stderr unless inetd_flag is set */ 170 int log_stderr = 0; 171 172 /* Saved arguments to main(). */ 173 char **saved_argv; 174 int saved_argc; 175 176 /* re-exec */ 177 int rexeced_flag = 0; 178 int rexec_flag = 1; 179 int rexec_argc = 0; 180 char **rexec_argv; 181 182 /* 183 * The sockets that the server is listening; this is used in the SIGHUP 184 * signal handler. 185 */ 186 #define MAX_LISTEN_SOCKS 16 187 int listen_socks[MAX_LISTEN_SOCKS]; 188 int num_listen_socks = 0; 189 190 /* 191 * the client's version string, passed by sshd2 in compat mode. if != NULL, 192 * sshd will skip the version-number exchange 193 */ 194 char *client_version_string = NULL; 195 char *server_version_string = NULL; 196 197 /* for rekeying XXX fixme */ 198 Kex *xxx_kex; 199 200 /* 201 * Any really sensitive data in the application is contained in this 202 * structure. The idea is that this structure could be locked into memory so 203 * that the pages do not get written into swap. However, there are some 204 * problems. The private key contains BIGNUMs, and we do not (in principle) 205 * have access to the internals of them, and locking just the structure is 206 * not very useful. Currently, memory locking is not implemented. 207 */ 208 struct { 209 Key *server_key; /* ephemeral server key */ 210 Key *ssh1_host_key; /* ssh1 host key */ 211 Key **host_keys; /* all private host keys */ 212 Key **host_certificates; /* all public host certificates */ 213 int have_ssh1_key; 214 int have_ssh2_key; 215 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 216 } sensitive_data; 217 218 /* 219 * Flag indicating whether the RSA server key needs to be regenerated. 220 * Is set in the SIGALRM handler and cleared when the key is regenerated. 221 */ 222 static volatile sig_atomic_t key_do_regen = 0; 223 224 /* This is set to true when a signal is received. */ 225 static volatile sig_atomic_t received_sighup = 0; 226 static volatile sig_atomic_t received_sigterm = 0; 227 228 /* session identifier, used by RSA-auth */ 229 u_char session_id[16]; 230 231 /* same for ssh2 */ 232 u_char *session_id2 = NULL; 233 u_int session_id2_len = 0; 234 235 /* record remote hostname or ip */ 236 u_int utmp_len = MAXHOSTNAMELEN; 237 238 /* options.max_startup sized array of fd ints */ 239 int *startup_pipes = NULL; 240 int startup_pipe; /* in child */ 241 242 /* variables used for privilege separation */ 243 int use_privsep = -1; 244 struct monitor *pmonitor = NULL; 245 246 /* global authentication context */ 247 Authctxt *the_authctxt = NULL; 248 249 /* sshd_config buffer */ 250 Buffer cfg; 251 252 /* message to be displayed after login */ 253 Buffer loginmsg; 254 255 /* Unprivileged user */ 256 struct passwd *privsep_pw = NULL; 257 258 /* Prototypes for various functions defined later in this file. */ 259 void destroy_sensitive_data(void); 260 void demote_sensitive_data(void); 261 262 static void do_ssh1_kex(void); 263 static void do_ssh2_kex(void); 264 265 /* 266 * Close all listening sockets 267 */ 268 static void 269 close_listen_socks(void) 270 { 271 int i; 272 273 for (i = 0; i < num_listen_socks; i++) 274 close(listen_socks[i]); 275 num_listen_socks = -1; 276 } 277 278 static void 279 close_startup_pipes(void) 280 { 281 int i; 282 283 if (startup_pipes) 284 for (i = 0; i < options.max_startups; i++) 285 if (startup_pipes[i] != -1) 286 close(startup_pipes[i]); 287 } 288 289 /* 290 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 291 * the effect is to reread the configuration file (and to regenerate 292 * the server key). 293 */ 294 295 /*ARGSUSED*/ 296 static void 297 sighup_handler(int sig) 298 { 299 int save_errno = errno; 300 301 received_sighup = 1; 302 signal(SIGHUP, sighup_handler); 303 errno = save_errno; 304 } 305 306 /* 307 * Called from the main program after receiving SIGHUP. 308 * Restarts the server. 309 */ 310 static void 311 sighup_restart(void) 312 { 313 logit("Received SIGHUP; restarting."); 314 close_listen_socks(); 315 close_startup_pipes(); 316 alarm(0); /* alarm timer persists across exec */ 317 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 318 execv(saved_argv[0], saved_argv); 319 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 320 strerror(errno)); 321 exit(1); 322 } 323 324 /* 325 * Generic signal handler for terminating signals in the master daemon. 326 */ 327 /*ARGSUSED*/ 328 static void 329 sigterm_handler(int sig) 330 { 331 received_sigterm = sig; 332 } 333 334 /* 335 * SIGCHLD handler. This is called whenever a child dies. This will then 336 * reap any zombies left by exited children. 337 */ 338 /*ARGSUSED*/ 339 static void 340 main_sigchld_handler(int sig) 341 { 342 int save_errno = errno; 343 pid_t pid; 344 int status; 345 346 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 347 (pid < 0 && errno == EINTR)) 348 ; 349 350 signal(SIGCHLD, main_sigchld_handler); 351 errno = save_errno; 352 } 353 354 /* 355 * Signal handler for the alarm after the login grace period has expired. 356 */ 357 /*ARGSUSED*/ 358 static void 359 grace_alarm_handler(int sig) 360 { 361 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 362 kill(pmonitor->m_pid, SIGALRM); 363 364 /* Log error and exit. */ 365 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 366 } 367 368 /* 369 * Signal handler for the key regeneration alarm. Note that this 370 * alarm only occurs in the daemon waiting for connections, and it does not 371 * do anything with the private key or random state before forking. 372 * Thus there should be no concurrency control/asynchronous execution 373 * problems. 374 */ 375 static void 376 generate_ephemeral_server_key(void) 377 { 378 verbose("Generating %s%d bit RSA key.", 379 sensitive_data.server_key ? "new " : "", options.server_key_bits); 380 if (sensitive_data.server_key != NULL) 381 key_free(sensitive_data.server_key); 382 sensitive_data.server_key = key_generate(KEY_RSA1, 383 options.server_key_bits); 384 verbose("RSA key generation complete."); 385 386 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 387 arc4random_stir(); 388 } 389 390 /*ARGSUSED*/ 391 static void 392 key_regeneration_alarm(int sig) 393 { 394 int save_errno = errno; 395 396 signal(SIGALRM, SIG_DFL); 397 errno = save_errno; 398 key_do_regen = 1; 399 } 400 401 static void 402 sshd_exchange_identification(int sock_in, int sock_out) 403 { 404 u_int i; 405 int mismatch; 406 int remote_major, remote_minor; 407 int major, minor; 408 char *s, *newline = "\n"; 409 char buf[256]; /* Must not be larger than remote_version. */ 410 char remote_version[256]; /* Must be at least as big as buf. */ 411 412 if ((options.protocol & SSH_PROTO_1) && 413 (options.protocol & SSH_PROTO_2)) { 414 major = PROTOCOL_MAJOR_1; 415 minor = 99; 416 } else if (options.protocol & SSH_PROTO_2) { 417 major = PROTOCOL_MAJOR_2; 418 minor = PROTOCOL_MINOR_2; 419 newline = "\r\n"; 420 } else { 421 major = PROTOCOL_MAJOR_1; 422 minor = PROTOCOL_MINOR_1; 423 } 424 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor, 425 SSH_RELEASE, newline); 426 server_version_string = xstrdup(buf); 427 428 /* Send our protocol version identification. */ 429 if (roaming_atomicio(vwrite, sock_out, server_version_string, 430 strlen(server_version_string)) 431 != strlen(server_version_string)) { 432 logit("Could not write ident string to %s", get_remote_ipaddr()); 433 cleanup_exit(255); 434 } 435 436 /* Read other sides version identification. */ 437 memset(buf, 0, sizeof(buf)); 438 for (i = 0; i < sizeof(buf) - 1; i++) { 439 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 440 logit("Did not receive identification string from %s", 441 get_remote_ipaddr()); 442 cleanup_exit(255); 443 } 444 if (buf[i] == '\r') { 445 buf[i] = 0; 446 /* Kludge for F-Secure Macintosh < 1.0.2 */ 447 if (i == 12 && 448 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 449 break; 450 continue; 451 } 452 if (buf[i] == '\n') { 453 buf[i] = 0; 454 break; 455 } 456 } 457 buf[sizeof(buf) - 1] = 0; 458 client_version_string = xstrdup(buf); 459 460 /* 461 * Check that the versions match. In future this might accept 462 * several versions and set appropriate flags to handle them. 463 */ 464 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 465 &remote_major, &remote_minor, remote_version) != 3) { 466 s = "Protocol mismatch.\n"; 467 (void) atomicio(vwrite, sock_out, s, strlen(s)); 468 close(sock_in); 469 close(sock_out); 470 logit("Bad protocol version identification '%.100s' from %s", 471 client_version_string, get_remote_ipaddr()); 472 cleanup_exit(255); 473 } 474 debug("Client protocol version %d.%d; client software version %.100s", 475 remote_major, remote_minor, remote_version); 476 logit("SSH: Server;Ltype: Version;Remote: %s-%d;Protocol: %d.%d;Client: %.100s", 477 get_remote_ipaddr(), get_remote_port(), 478 remote_major, remote_minor, remote_version); 479 480 compat_datafellows(remote_version); 481 482 if (datafellows & SSH_BUG_PROBE) { 483 logit("probed from %s with %s. Don't panic.", 484 get_remote_ipaddr(), client_version_string); 485 cleanup_exit(255); 486 } 487 488 if (datafellows & SSH_BUG_SCANNER) { 489 logit("scanned from %s with %s. Don't panic.", 490 get_remote_ipaddr(), client_version_string); 491 cleanup_exit(255); 492 } 493 494 mismatch = 0; 495 switch (remote_major) { 496 case 1: 497 if (remote_minor == 99) { 498 if (options.protocol & SSH_PROTO_2) 499 enable_compat20(); 500 else 501 mismatch = 1; 502 break; 503 } 504 if (!(options.protocol & SSH_PROTO_1)) { 505 mismatch = 1; 506 break; 507 } 508 if (remote_minor < 3) { 509 packet_disconnect("Your ssh version is too old and " 510 "is no longer supported. Please install a newer version."); 511 } else if (remote_minor == 3) { 512 /* note that this disables agent-forwarding */ 513 enable_compat13(); 514 } 515 break; 516 case 2: 517 if (options.protocol & SSH_PROTO_2) { 518 enable_compat20(); 519 break; 520 } 521 /* FALLTHROUGH */ 522 default: 523 mismatch = 1; 524 break; 525 } 526 chop(server_version_string); 527 debug("Local version string %.200s", server_version_string); 528 529 if (mismatch) { 530 s = "Protocol major versions differ.\n"; 531 (void) atomicio(vwrite, sock_out, s, strlen(s)); 532 close(sock_in); 533 close(sock_out); 534 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 535 get_remote_ipaddr(), 536 server_version_string, client_version_string); 537 cleanup_exit(255); 538 } 539 } 540 541 /* Destroy the host and server keys. They will no longer be needed. */ 542 void 543 destroy_sensitive_data(void) 544 { 545 int i; 546 547 if (sensitive_data.server_key) { 548 key_free(sensitive_data.server_key); 549 sensitive_data.server_key = NULL; 550 } 551 for (i = 0; i < options.num_host_key_files; i++) { 552 if (sensitive_data.host_keys[i]) { 553 key_free(sensitive_data.host_keys[i]); 554 sensitive_data.host_keys[i] = NULL; 555 } 556 if (sensitive_data.host_certificates[i]) { 557 key_free(sensitive_data.host_certificates[i]); 558 sensitive_data.host_certificates[i] = NULL; 559 } 560 } 561 sensitive_data.ssh1_host_key = NULL; 562 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); 563 } 564 565 /* Demote private to public keys for network child */ 566 void 567 demote_sensitive_data(void) 568 { 569 Key *tmp; 570 int i; 571 572 if (sensitive_data.server_key) { 573 tmp = key_demote(sensitive_data.server_key); 574 key_free(sensitive_data.server_key); 575 sensitive_data.server_key = tmp; 576 } 577 578 for (i = 0; i < options.num_host_key_files; i++) { 579 if (sensitive_data.host_keys[i]) { 580 tmp = key_demote(sensitive_data.host_keys[i]); 581 key_free(sensitive_data.host_keys[i]); 582 sensitive_data.host_keys[i] = tmp; 583 if (tmp->type == KEY_RSA1) 584 sensitive_data.ssh1_host_key = tmp; 585 } 586 /* Certs do not need demotion */ 587 } 588 589 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 590 } 591 592 static void 593 privsep_preauth_child(void) 594 { 595 u_int32_t rnd[256]; 596 gid_t gidset[1]; 597 598 /* Enable challenge-response authentication for privilege separation */ 599 privsep_challenge_enable(); 600 601 arc4random_stir(); 602 arc4random_buf(rnd, sizeof(rnd)); 603 RAND_seed(rnd, sizeof(rnd)); 604 605 /* Demote the private keys to public keys. */ 606 demote_sensitive_data(); 607 608 /* Change our root directory */ 609 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 610 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 611 strerror(errno)); 612 if (chdir("/") == -1) 613 fatal("chdir(\"/\"): %s", strerror(errno)); 614 615 /* Drop our privileges */ 616 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 617 (u_int)privsep_pw->pw_gid); 618 #if 0 619 /* XXX not ready, too heavy after chroot */ 620 do_setusercontext(privsep_pw); 621 #else 622 gidset[0] = privsep_pw->pw_gid; 623 if (setgroups(1, gidset) < 0) 624 fatal("setgroups: %.100s", strerror(errno)); 625 permanently_set_uid(privsep_pw); 626 #endif 627 } 628 629 static int 630 privsep_preauth(Authctxt *authctxt) 631 { 632 int status; 633 pid_t pid; 634 635 /* Set up unprivileged child process to deal with network data */ 636 pmonitor = monitor_init(); 637 /* Store a pointer to the kex for later rekeying */ 638 pmonitor->m_pkex = &xxx_kex; 639 640 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 close(pmonitor->m_recvfd); 647 pmonitor->m_pid = pid; 648 monitor_child_preauth(authctxt, pmonitor); 649 close(pmonitor->m_sendfd); 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 break; 658 return (1); 659 } else { 660 /* child */ 661 662 close(pmonitor->m_sendfd); 663 664 /* Demote the child */ 665 if (getuid() == 0 || geteuid() == 0) 666 privsep_preauth_child(); 667 setproctitle("%s", "[net]"); 668 } 669 return (0); 670 } 671 672 static void 673 privsep_postauth(Authctxt *authctxt) 674 { 675 u_int32_t rnd[256]; 676 677 #ifdef DISABLE_FD_PASSING 678 if (1) { 679 #else 680 if (authctxt->pw->pw_uid == 0 || options.use_login) { 681 #endif 682 /* File descriptor passing is broken or root login */ 683 use_privsep = 0; 684 goto skip; 685 } 686 687 /* New socket pair */ 688 monitor_reinit(pmonitor); 689 690 pmonitor->m_pid = fork(); 691 if (pmonitor->m_pid == -1) 692 fatal("fork of unprivileged child failed"); 693 else if (pmonitor->m_pid != 0) { 694 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 695 close(pmonitor->m_recvfd); 696 buffer_clear(&loginmsg); 697 monitor_child_postauth(pmonitor); 698 699 /* NEVERREACHED */ 700 exit(0); 701 } 702 703 close(pmonitor->m_sendfd); 704 705 /* Demote the private keys to public keys. */ 706 demote_sensitive_data(); 707 708 arc4random_stir(); 709 arc4random_buf(rnd, sizeof(rnd)); 710 RAND_seed(rnd, sizeof(rnd)); 711 712 /* Drop privileges */ 713 do_setusercontext(authctxt->pw); 714 715 skip: 716 /* It is safe now to apply the key state */ 717 monitor_apply_keystate(pmonitor); 718 719 /* 720 * Tell the packet layer that authentication was successful, since 721 * this information is not part of the key state. 722 */ 723 packet_set_authenticated(); 724 } 725 726 static char * 727 list_hostkey_types(void) 728 { 729 Buffer b; 730 const char *p; 731 char *ret; 732 int i; 733 Key *key; 734 735 buffer_init(&b); 736 for (i = 0; i < options.num_host_key_files; i++) { 737 key = sensitive_data.host_keys[i]; 738 if (key == NULL) 739 continue; 740 switch (key->type) { 741 case KEY_RSA: 742 case KEY_DSA: 743 if (buffer_len(&b) > 0) 744 buffer_append(&b, ",", 1); 745 p = key_ssh_name(key); 746 buffer_append(&b, p, strlen(p)); 747 break; 748 } 749 /* If the private key has a cert peer, then list that too */ 750 key = sensitive_data.host_certificates[i]; 751 if (key == NULL) 752 continue; 753 switch (key->type) { 754 case KEY_RSA_CERT_V00: 755 case KEY_DSA_CERT_V00: 756 case KEY_RSA_CERT: 757 case KEY_DSA_CERT: 758 if (buffer_len(&b) > 0) 759 buffer_append(&b, ",", 1); 760 p = key_ssh_name(key); 761 buffer_append(&b, p, strlen(p)); 762 break; 763 } 764 } 765 buffer_append(&b, "\0", 1); 766 ret = xstrdup(buffer_ptr(&b)); 767 buffer_free(&b); 768 debug("list_hostkey_types: %s", ret); 769 return ret; 770 } 771 772 static Key * 773 get_hostkey_by_type(int type, int need_private) 774 { 775 int i; 776 Key *key; 777 778 for (i = 0; i < options.num_host_key_files; i++) { 779 switch (type) { 780 case KEY_RSA_CERT_V00: 781 case KEY_DSA_CERT_V00: 782 case KEY_RSA_CERT: 783 case KEY_DSA_CERT: 784 key = sensitive_data.host_certificates[i]; 785 break; 786 default: 787 key = sensitive_data.host_keys[i]; 788 break; 789 } 790 if (key != NULL && key->type == type) 791 return need_private ? 792 sensitive_data.host_keys[i] : key; 793 } 794 return NULL; 795 } 796 797 Key * 798 get_hostkey_public_by_type(int type) 799 { 800 return get_hostkey_by_type(type, 0); 801 } 802 803 Key * 804 get_hostkey_private_by_type(int type) 805 { 806 return get_hostkey_by_type(type, 1); 807 } 808 809 Key * 810 get_hostkey_by_index(int ind) 811 { 812 if (ind < 0 || ind >= options.num_host_key_files) 813 return (NULL); 814 return (sensitive_data.host_keys[ind]); 815 } 816 817 int 818 get_hostkey_index(Key *key) 819 { 820 int i; 821 822 for (i = 0; i < options.num_host_key_files; i++) { 823 if (key_is_cert(key)) { 824 if (key == sensitive_data.host_certificates[i]) 825 return (i); 826 } else { 827 if (key == sensitive_data.host_keys[i]) 828 return (i); 829 } 830 } 831 return (-1); 832 } 833 834 /* 835 * returns 1 if connection should be dropped, 0 otherwise. 836 * dropping starts at connection #max_startups_begin with a probability 837 * of (max_startups_rate/100). the probability increases linearly until 838 * all connections are dropped for startups > max_startups 839 */ 840 static int 841 drop_connection(int startups) 842 { 843 int p, r; 844 845 if (startups < options.max_startups_begin) 846 return 0; 847 if (startups >= options.max_startups) 848 return 1; 849 if (options.max_startups_rate == 100) 850 return 1; 851 852 p = 100 - options.max_startups_rate; 853 p *= startups - options.max_startups_begin; 854 p /= options.max_startups - options.max_startups_begin; 855 p += options.max_startups_rate; 856 r = arc4random_uniform(100); 857 858 debug("drop_connection: p %d, r %d", p, r); 859 return (r < p) ? 1 : 0; 860 } 861 862 static void 863 usage(void) 864 { 865 fprintf(stderr, "%s, %s\n", 866 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); 867 fprintf(stderr, 868 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 869 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n" 870 " [-k key_gen_time] [-o option] [-p port] [-u len]\n" 871 ); 872 exit(1); 873 } 874 875 static void 876 send_rexec_state(int fd, Buffer *conf) 877 { 878 Buffer m; 879 880 debug3("%s: entering fd = %d config len %d", __func__, fd, 881 buffer_len(conf)); 882 883 /* 884 * Protocol from reexec master to child: 885 * string configuration 886 * u_int ephemeral_key_follows 887 * bignum e (only if ephemeral_key_follows == 1) 888 * bignum n " 889 * bignum d " 890 * bignum iqmp " 891 * bignum p " 892 * bignum q " 893 * string rngseed (only if OpenSSL is not self-seeded) 894 */ 895 buffer_init(&m); 896 buffer_put_cstring(&m, buffer_ptr(conf)); 897 898 if (sensitive_data.server_key != NULL && 899 sensitive_data.server_key->type == KEY_RSA1) { 900 buffer_put_int(&m, 1); 901 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 902 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 903 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 904 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 905 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 906 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 907 } else 908 buffer_put_int(&m, 0); 909 910 #ifndef OPENSSL_PRNG_ONLY 911 rexec_send_rng_seed(&m); 912 #endif 913 914 if (ssh_msg_send(fd, 0, &m) == -1) 915 fatal("%s: ssh_msg_send failed", __func__); 916 917 buffer_free(&m); 918 919 debug3("%s: done", __func__); 920 } 921 922 static void 923 recv_rexec_state(int fd, Buffer *conf) 924 { 925 Buffer m; 926 char *cp; 927 u_int len; 928 929 debug3("%s: entering fd = %d", __func__, fd); 930 931 buffer_init(&m); 932 933 if (ssh_msg_recv(fd, &m) == -1) 934 fatal("%s: ssh_msg_recv failed", __func__); 935 if (buffer_get_char(&m) != 0) 936 fatal("%s: rexec version mismatch", __func__); 937 938 cp = buffer_get_string(&m, &len); 939 if (conf != NULL) 940 buffer_append(conf, cp, len + 1); 941 xfree(cp); 942 943 if (buffer_get_int(&m)) { 944 if (sensitive_data.server_key != NULL) 945 key_free(sensitive_data.server_key); 946 sensitive_data.server_key = key_new_private(KEY_RSA1); 947 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 948 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 949 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 950 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 951 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 952 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 953 rsa_generate_additional_parameters( 954 sensitive_data.server_key->rsa); 955 } 956 957 #ifndef OPENSSL_PRNG_ONLY 958 rexec_recv_rng_seed(&m); 959 #endif 960 961 buffer_free(&m); 962 963 debug3("%s: done", __func__); 964 } 965 966 /* Accept a connection from inetd */ 967 static void 968 server_accept_inetd(int *sock_in, int *sock_out) 969 { 970 int fd; 971 972 startup_pipe = -1; 973 if (rexeced_flag) { 974 close(REEXEC_CONFIG_PASS_FD); 975 *sock_in = *sock_out = dup(STDIN_FILENO); 976 if (!debug_flag) { 977 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 978 close(REEXEC_STARTUP_PIPE_FD); 979 } 980 } else { 981 *sock_in = dup(STDIN_FILENO); 982 *sock_out = dup(STDOUT_FILENO); 983 } 984 /* 985 * We intentionally do not close the descriptors 0, 1, and 2 986 * as our code for setting the descriptors won't work if 987 * ttyfd happens to be one of those. 988 */ 989 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 990 dup2(fd, STDIN_FILENO); 991 dup2(fd, STDOUT_FILENO); 992 if (fd > STDOUT_FILENO) 993 close(fd); 994 } 995 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 996 } 997 998 /* 999 * Listen for TCP connections 1000 */ 1001 static void 1002 server_listen(void) 1003 { 1004 int ret, listen_sock, on = 1; 1005 struct addrinfo *ai; 1006 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1007 int socksize; 1008 int socksizelen = sizeof(int); 1009 1010 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1011 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1012 continue; 1013 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1014 fatal("Too many listen sockets. " 1015 "Enlarge MAX_LISTEN_SOCKS"); 1016 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1017 ntop, sizeof(ntop), strport, sizeof(strport), 1018 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1019 error("getnameinfo failed: %.100s", 1020 ssh_gai_strerror(ret)); 1021 continue; 1022 } 1023 /* Create socket for listening. */ 1024 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1025 ai->ai_protocol); 1026 if (listen_sock < 0) { 1027 /* kernel may not support ipv6 */ 1028 verbose("socket: %.100s", strerror(errno)); 1029 continue; 1030 } 1031 if (set_nonblock(listen_sock) == -1) { 1032 close(listen_sock); 1033 continue; 1034 } 1035 /* 1036 * Set socket options. 1037 * Allow local port reuse in TIME_WAIT. 1038 */ 1039 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1040 &on, sizeof(on)) == -1) 1041 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1042 1043 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1044 if (ai->ai_family == AF_INET6) 1045 sock_set_v6only(listen_sock); 1046 1047 debug("Bind to port %s on %s.", strport, ntop); 1048 1049 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, 1050 &socksize, &socksizelen); 1051 debug("Server TCP RWIN socket size: %d", socksize); 1052 debug("HPN Buffer Size: %d", options.hpn_buffer_size); 1053 1054 /* Bind the socket to the desired port. */ 1055 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1056 error("Bind to port %s on %s failed: %.200s.", 1057 strport, ntop, strerror(errno)); 1058 close(listen_sock); 1059 continue; 1060 } 1061 listen_socks[num_listen_socks] = listen_sock; 1062 num_listen_socks++; 1063 1064 /* Start listening on the port. */ 1065 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1066 fatal("listen on [%s]:%s: %.100s", 1067 ntop, strport, strerror(errno)); 1068 logit("Server listening on %s port %s.", ntop, strport); 1069 } 1070 freeaddrinfo(options.listen_addrs); 1071 1072 if (!num_listen_socks) 1073 fatal("Cannot bind any address."); 1074 } 1075 1076 /* 1077 * The main TCP accept loop. Note that, for the non-debug case, returns 1078 * from this function are in a forked subprocess. 1079 */ 1080 static void 1081 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1082 { 1083 fd_set *fdset; 1084 int i, j, ret, maxfd; 1085 int key_used = 0, startups = 0; 1086 int startup_p[2] = { -1 , -1 }; 1087 struct sockaddr_storage from; 1088 socklen_t fromlen; 1089 pid_t pid; 1090 1091 /* setup fd set for accept */ 1092 fdset = NULL; 1093 maxfd = 0; 1094 for (i = 0; i < num_listen_socks; i++) 1095 if (listen_socks[i] > maxfd) 1096 maxfd = listen_socks[i]; 1097 /* pipes connected to unauthenticated childs */ 1098 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1099 for (i = 0; i < options.max_startups; i++) 1100 startup_pipes[i] = -1; 1101 1102 /* 1103 * Stay listening for connections until the system crashes or 1104 * the daemon is killed with a signal. 1105 */ 1106 for (;;) { 1107 if (received_sighup) 1108 sighup_restart(); 1109 if (fdset != NULL) 1110 xfree(fdset); 1111 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1112 sizeof(fd_mask)); 1113 1114 for (i = 0; i < num_listen_socks; i++) 1115 FD_SET(listen_socks[i], fdset); 1116 for (i = 0; i < options.max_startups; i++) 1117 if (startup_pipes[i] != -1) 1118 FD_SET(startup_pipes[i], fdset); 1119 1120 /* Wait in select until there is a connection. */ 1121 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1122 if (ret < 0 && errno != EINTR) 1123 error("select: %.100s", strerror(errno)); 1124 if (received_sigterm) { 1125 logit("Received signal %d; terminating.", 1126 (int) received_sigterm); 1127 close_listen_socks(); 1128 unlink(options.pid_file); 1129 exit(255); 1130 } 1131 if (key_used && key_do_regen) { 1132 generate_ephemeral_server_key(); 1133 key_used = 0; 1134 key_do_regen = 0; 1135 } 1136 if (ret < 0) 1137 continue; 1138 1139 for (i = 0; i < options.max_startups; i++) 1140 if (startup_pipes[i] != -1 && 1141 FD_ISSET(startup_pipes[i], fdset)) { 1142 /* 1143 * the read end of the pipe is ready 1144 * if the child has closed the pipe 1145 * after successful authentication 1146 * or if the child has died 1147 */ 1148 close(startup_pipes[i]); 1149 startup_pipes[i] = -1; 1150 startups--; 1151 } 1152 for (i = 0; i < num_listen_socks; i++) { 1153 if (!FD_ISSET(listen_socks[i], fdset)) 1154 continue; 1155 fromlen = sizeof(from); 1156 *newsock = accept(listen_socks[i], 1157 (struct sockaddr *)&from, &fromlen); 1158 if (*newsock < 0) { 1159 if (errno != EINTR && errno != EAGAIN && 1160 errno != EWOULDBLOCK) 1161 error("accept: %.100s", strerror(errno)); 1162 continue; 1163 } 1164 if (unset_nonblock(*newsock) == -1) { 1165 close(*newsock); 1166 continue; 1167 } 1168 if (drop_connection(startups) == 1) { 1169 debug("drop connection #%d", startups); 1170 close(*newsock); 1171 continue; 1172 } 1173 if (pipe(startup_p) == -1) { 1174 close(*newsock); 1175 continue; 1176 } 1177 1178 if (rexec_flag && socketpair(AF_UNIX, 1179 SOCK_STREAM, 0, config_s) == -1) { 1180 error("reexec socketpair: %s", 1181 strerror(errno)); 1182 close(*newsock); 1183 close(startup_p[0]); 1184 close(startup_p[1]); 1185 continue; 1186 } 1187 1188 for (j = 0; j < options.max_startups; j++) 1189 if (startup_pipes[j] == -1) { 1190 startup_pipes[j] = startup_p[0]; 1191 if (maxfd < startup_p[0]) 1192 maxfd = startup_p[0]; 1193 startups++; 1194 break; 1195 } 1196 1197 /* 1198 * Got connection. Fork a child to handle it, unless 1199 * we are in debugging mode. 1200 */ 1201 if (debug_flag) { 1202 /* 1203 * In debugging mode. Close the listening 1204 * socket, and start processing the 1205 * connection without forking. 1206 */ 1207 debug("Server will not fork when running in debugging mode."); 1208 close_listen_socks(); 1209 *sock_in = *newsock; 1210 *sock_out = *newsock; 1211 close(startup_p[0]); 1212 close(startup_p[1]); 1213 startup_pipe = -1; 1214 pid = getpid(); 1215 if (rexec_flag) { 1216 send_rexec_state(config_s[0], 1217 &cfg); 1218 close(config_s[0]); 1219 } 1220 break; 1221 } 1222 1223 /* 1224 * Normal production daemon. Fork, and have 1225 * the child process the connection. The 1226 * parent continues listening. 1227 */ 1228 platform_pre_fork(); 1229 if ((pid = fork()) == 0) { 1230 /* 1231 * Child. Close the listening and 1232 * max_startup sockets. Start using 1233 * the accepted socket. Reinitialize 1234 * logging (since our pid has changed). 1235 * We break out of the loop to handle 1236 * the connection. 1237 */ 1238 platform_post_fork_child(); 1239 startup_pipe = startup_p[1]; 1240 close_startup_pipes(); 1241 close_listen_socks(); 1242 *sock_in = *newsock; 1243 *sock_out = *newsock; 1244 log_init(__progname, 1245 options.log_level, 1246 options.log_facility, 1247 log_stderr); 1248 if (rexec_flag) 1249 close(config_s[0]); 1250 break; 1251 } 1252 1253 /* Parent. Stay in the loop. */ 1254 platform_post_fork_parent(pid); 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 #ifdef HAVE_SECUREWARE 1317 (void)set_auth_parameters(ac, av); 1318 #endif 1319 __progname = ssh_get_progname(av[0]); 1320 init_rng(); 1321 1322 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1323 saved_argc = ac; 1324 rexec_argc = ac; 1325 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1326 for (i = 0; i < ac; i++) 1327 saved_argv[i] = xstrdup(av[i]); 1328 saved_argv[i] = NULL; 1329 1330 #ifndef HAVE_SETPROCTITLE 1331 /* Prepare for later setproctitle emulation */ 1332 compat_init_setproctitle(ac, av); 1333 av = saved_argv; 1334 #endif 1335 1336 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1337 debug("setgroups(): %.200s", strerror(errno)); 1338 1339 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1340 sanitise_stdfd(); 1341 1342 /* Initialize configuration options to their default values. */ 1343 initialize_server_options(&options); 1344 1345 /* Parse command-line arguments. */ 1346 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) { 1347 switch (opt) { 1348 case '4': 1349 options.address_family = AF_INET; 1350 break; 1351 case '6': 1352 options.address_family = AF_INET6; 1353 break; 1354 case 'f': 1355 config_file_name = optarg; 1356 break; 1357 case 'c': 1358 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1359 fprintf(stderr, "too many host certificates.\n"); 1360 exit(1); 1361 } 1362 options.host_cert_files[options.num_host_cert_files++] = 1363 derelativise_path(optarg); 1364 break; 1365 case 'd': 1366 if (debug_flag == 0) { 1367 debug_flag = 1; 1368 options.log_level = SYSLOG_LEVEL_DEBUG1; 1369 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1370 options.log_level++; 1371 break; 1372 case 'D': 1373 no_daemon_flag = 1; 1374 break; 1375 case 'e': 1376 log_stderr = 1; 1377 break; 1378 case 'i': 1379 inetd_flag = 1; 1380 break; 1381 case 'r': 1382 rexec_flag = 0; 1383 break; 1384 case 'R': 1385 rexeced_flag = 1; 1386 inetd_flag = 1; 1387 break; 1388 case 'Q': 1389 /* ignored */ 1390 break; 1391 case 'q': 1392 options.log_level = SYSLOG_LEVEL_QUIET; 1393 break; 1394 case 'b': 1395 options.server_key_bits = (int)strtonum(optarg, 256, 1396 32768, NULL); 1397 break; 1398 case 'p': 1399 options.ports_from_cmdline = 1; 1400 if (options.num_ports >= MAX_PORTS) { 1401 fprintf(stderr, "too many ports.\n"); 1402 exit(1); 1403 } 1404 options.ports[options.num_ports++] = a2port(optarg); 1405 if (options.ports[options.num_ports-1] <= 0) { 1406 fprintf(stderr, "Bad port number.\n"); 1407 exit(1); 1408 } 1409 break; 1410 case 'g': 1411 if ((options.login_grace_time = convtime(optarg)) == -1) { 1412 fprintf(stderr, "Invalid login grace time.\n"); 1413 exit(1); 1414 } 1415 break; 1416 case 'k': 1417 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1418 fprintf(stderr, "Invalid key regeneration interval.\n"); 1419 exit(1); 1420 } 1421 break; 1422 case 'h': 1423 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1424 fprintf(stderr, "too many host keys.\n"); 1425 exit(1); 1426 } 1427 options.host_key_files[options.num_host_key_files++] = 1428 derelativise_path(optarg); 1429 break; 1430 case 't': 1431 test_flag = 1; 1432 break; 1433 case 'T': 1434 test_flag = 2; 1435 break; 1436 case 'C': 1437 cp = optarg; 1438 while ((p = strsep(&cp, ",")) && *p != '\0') { 1439 if (strncmp(p, "addr=", 5) == 0) 1440 test_addr = xstrdup(p + 5); 1441 else if (strncmp(p, "host=", 5) == 0) 1442 test_host = xstrdup(p + 5); 1443 else if (strncmp(p, "user=", 5) == 0) 1444 test_user = xstrdup(p + 5); 1445 else { 1446 fprintf(stderr, "Invalid test " 1447 "mode specification %s\n", p); 1448 exit(1); 1449 } 1450 } 1451 break; 1452 case 'u': 1453 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1454 if (utmp_len > MAXHOSTNAMELEN) { 1455 fprintf(stderr, "Invalid utmp length.\n"); 1456 exit(1); 1457 } 1458 break; 1459 case 'o': 1460 line = xstrdup(optarg); 1461 if (process_server_config_line(&options, line, 1462 "command-line", 0, NULL, NULL, NULL, NULL) != 0) 1463 exit(1); 1464 xfree(line); 1465 break; 1466 case '?': 1467 default: 1468 usage(); 1469 break; 1470 } 1471 } 1472 if (rexeced_flag || inetd_flag) 1473 rexec_flag = 0; 1474 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1475 fatal("sshd re-exec requires execution with an absolute path"); 1476 if (rexeced_flag) 1477 closefrom(REEXEC_MIN_FREE_FD); 1478 else 1479 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1480 1481 SSLeay_add_all_algorithms(); 1482 1483 /* 1484 * Force logging to stderr until we have loaded the private host 1485 * key (unless started from inetd) 1486 */ 1487 log_init(__progname, 1488 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1489 SYSLOG_LEVEL_INFO : options.log_level, 1490 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1491 SYSLOG_FACILITY_AUTH : options.log_facility, 1492 log_stderr || !inetd_flag); 1493 1494 /* 1495 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1496 * root's environment 1497 */ 1498 if (getenv("KRB5CCNAME") != NULL) 1499 unsetenv("KRB5CCNAME"); 1500 1501 #ifdef _UNICOS 1502 /* Cray can define user privs drop all privs now! 1503 * Not needed on PRIV_SU systems! 1504 */ 1505 drop_cray_privs(); 1506 #endif 1507 1508 sensitive_data.server_key = NULL; 1509 sensitive_data.ssh1_host_key = NULL; 1510 sensitive_data.have_ssh1_key = 0; 1511 sensitive_data.have_ssh2_key = 0; 1512 1513 /* 1514 * If we're doing an extended config test, make sure we have all of 1515 * the parameters we need. If we're not doing an extended test, 1516 * do not silently ignore connection test params. 1517 */ 1518 if (test_flag >= 2 && 1519 (test_user != NULL || test_host != NULL || test_addr != NULL) 1520 && (test_user == NULL || test_host == NULL || test_addr == NULL)) 1521 fatal("user, host and addr are all required when testing " 1522 "Match configs"); 1523 if (test_flag < 2 && (test_user != NULL || test_host != NULL || 1524 test_addr != NULL)) 1525 fatal("Config test connection parameter (-C) provided without " 1526 "test mode (-T)"); 1527 1528 /* Fetch our configuration */ 1529 buffer_init(&cfg); 1530 if (rexeced_flag) 1531 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1532 else 1533 load_server_config(config_file_name, &cfg); 1534 1535 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1536 &cfg, NULL, NULL, NULL); 1537 1538 seed_rng(); 1539 1540 /* Fill in default values for those options not explicitly set. */ 1541 fill_default_server_options(&options); 1542 1543 /* challenge-response is implemented via keyboard interactive */ 1544 if (options.challenge_response_authentication) 1545 options.kbd_interactive_authentication = 1; 1546 1547 /* set default channel AF */ 1548 channel_set_af(options.address_family); 1549 1550 /* Check that there are no remaining arguments. */ 1551 if (optind < ac) { 1552 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1553 exit(1); 1554 } 1555 1556 debug("sshd version %.100s", SSH_RELEASE); 1557 1558 /* Store privilege separation user for later use if required. */ 1559 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1560 if (use_privsep || options.kerberos_authentication) 1561 fatal("Privilege separation user %s does not exist", 1562 SSH_PRIVSEP_USER); 1563 } else { 1564 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd)); 1565 privsep_pw = pwcopy(privsep_pw); 1566 xfree(privsep_pw->pw_passwd); 1567 privsep_pw->pw_passwd = xstrdup("*"); 1568 } 1569 endpwent(); 1570 1571 /* load private host keys */ 1572 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1573 sizeof(Key *)); 1574 for (i = 0; i < options.num_host_key_files; i++) 1575 sensitive_data.host_keys[i] = NULL; 1576 1577 for (i = 0; i < options.num_host_key_files; i++) { 1578 key = key_load_private(options.host_key_files[i], "", NULL); 1579 if (key && blacklisted_key(key)) { 1580 char *fp; 1581 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 1582 if (options.permit_blacklisted_keys) 1583 error("Host key %s blacklisted (see " 1584 "ssh-vulnkey(1)); continuing anyway", fp); 1585 else 1586 error("Host key %s blacklisted (see " 1587 "ssh-vulnkey(1))", fp); 1588 xfree(fp); 1589 if (!options.permit_blacklisted_keys) { 1590 sensitive_data.host_keys[i] = NULL; 1591 continue; 1592 } 1593 } 1594 sensitive_data.host_keys[i] = key; 1595 if (key == NULL) { 1596 error("Could not load host key: %s", 1597 options.host_key_files[i]); 1598 sensitive_data.host_keys[i] = NULL; 1599 continue; 1600 } 1601 switch (key->type) { 1602 case KEY_RSA1: 1603 sensitive_data.ssh1_host_key = key; 1604 sensitive_data.have_ssh1_key = 1; 1605 break; 1606 case KEY_RSA: 1607 case KEY_DSA: 1608 sensitive_data.have_ssh2_key = 1; 1609 break; 1610 } 1611 debug("private host key: #%d type %d %s", i, key->type, 1612 key_type(key)); 1613 } 1614 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1615 logit("Disabling protocol version 1. Could not load host key"); 1616 options.protocol &= ~SSH_PROTO_1; 1617 } 1618 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1619 logit("Disabling protocol version 2. Could not load host key"); 1620 options.protocol &= ~SSH_PROTO_2; 1621 } 1622 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1623 logit("sshd: no hostkeys available -- exiting."); 1624 exit(1); 1625 } 1626 1627 /* 1628 * Load certificates. They are stored in an array at identical 1629 * indices to the public keys that they relate to. 1630 */ 1631 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1632 sizeof(Key *)); 1633 for (i = 0; i < options.num_host_key_files; i++) 1634 sensitive_data.host_certificates[i] = NULL; 1635 1636 for (i = 0; i < options.num_host_cert_files; i++) { 1637 key = key_load_public(options.host_cert_files[i], NULL); 1638 if (key == NULL) { 1639 error("Could not load host certificate: %s", 1640 options.host_cert_files[i]); 1641 continue; 1642 } 1643 if (!key_is_cert(key)) { 1644 error("Certificate file is not a certificate: %s", 1645 options.host_cert_files[i]); 1646 key_free(key); 1647 continue; 1648 } 1649 /* Find matching private key */ 1650 for (j = 0; j < options.num_host_key_files; j++) { 1651 if (key_equal_public(key, 1652 sensitive_data.host_keys[j])) { 1653 sensitive_data.host_certificates[j] = key; 1654 break; 1655 } 1656 } 1657 if (j >= options.num_host_key_files) { 1658 error("No matching private key for certificate: %s", 1659 options.host_cert_files[i]); 1660 key_free(key); 1661 continue; 1662 } 1663 sensitive_data.host_certificates[j] = key; 1664 debug("host certificate: #%d type %d %s", j, key->type, 1665 key_type(key)); 1666 } 1667 /* Check certain values for sanity. */ 1668 if (options.protocol & SSH_PROTO_1) { 1669 if (options.server_key_bits < 512 || 1670 options.server_key_bits > 32768) { 1671 fprintf(stderr, "Bad server key size.\n"); 1672 exit(1); 1673 } 1674 /* 1675 * Check that server and host key lengths differ sufficiently. This 1676 * is necessary to make double encryption work with rsaref. Oh, I 1677 * hate software patents. I dont know if this can go? Niels 1678 */ 1679 if (options.server_key_bits > 1680 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1681 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1682 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1683 SSH_KEY_BITS_RESERVED) { 1684 options.server_key_bits = 1685 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1686 SSH_KEY_BITS_RESERVED; 1687 debug("Forcing server key to %d bits to make it differ from host key.", 1688 options.server_key_bits); 1689 } 1690 } 1691 1692 if (use_privsep) { 1693 struct stat st; 1694 1695 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1696 (S_ISDIR(st.st_mode) == 0)) 1697 fatal("Missing privilege separation directory: %s", 1698 _PATH_PRIVSEP_CHROOT_DIR); 1699 1700 #ifdef HAVE_CYGWIN 1701 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1702 (st.st_uid != getuid () || 1703 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1704 #else 1705 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1706 #endif 1707 fatal("%s must be owned by root and not group or " 1708 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1709 } 1710 1711 if (test_flag > 1) { 1712 if (test_user != NULL && test_addr != NULL && test_host != NULL) 1713 parse_server_match_config(&options, test_user, 1714 test_host, test_addr); 1715 dump_config(&options); 1716 } 1717 1718 /* Configuration looks good, so exit if in test mode. */ 1719 if (test_flag) 1720 exit(0); 1721 1722 /* 1723 * Clear out any supplemental groups we may have inherited. This 1724 * prevents inadvertent creation of files with bad modes (in the 1725 * portable version at least, it's certainly possible for PAM 1726 * to create a file, and we can't control the code in every 1727 * module which might be used). 1728 */ 1729 if (setgroups(0, NULL) < 0) 1730 debug("setgroups() failed: %.200s", strerror(errno)); 1731 1732 if (rexec_flag) { 1733 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1734 for (i = 0; i < rexec_argc; i++) { 1735 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1736 rexec_argv[i] = saved_argv[i]; 1737 } 1738 rexec_argv[rexec_argc] = "-R"; 1739 rexec_argv[rexec_argc + 1] = NULL; 1740 } 1741 1742 /* Ensure that umask disallows at least group and world write */ 1743 new_umask = umask(0077) | 0022; 1744 (void) umask(new_umask); 1745 1746 /* Initialize the log (it is reinitialized below in case we forked). */ 1747 if (debug_flag && (!inetd_flag || rexeced_flag)) 1748 log_stderr = 1; 1749 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1750 1751 /* 1752 * If not in debugging mode, and not started from inetd, disconnect 1753 * from the controlling terminal, and fork. The original process 1754 * exits. 1755 */ 1756 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1757 #ifdef TIOCNOTTY 1758 int fd; 1759 #endif /* TIOCNOTTY */ 1760 if (daemon(0, 0) < 0) 1761 fatal("daemon() failed: %.200s", strerror(errno)); 1762 1763 /* Disconnect from the controlling tty. */ 1764 #ifdef TIOCNOTTY 1765 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1766 if (fd >= 0) { 1767 (void) ioctl(fd, TIOCNOTTY, NULL); 1768 close(fd); 1769 } 1770 #endif /* TIOCNOTTY */ 1771 } 1772 /* Reinitialize the log (because of the fork above). */ 1773 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1774 1775 /* Initialize the random number generator. */ 1776 arc4random_stir(); 1777 1778 /* Chdir to the root directory so that the current disk can be 1779 unmounted if desired. */ 1780 chdir("/"); 1781 1782 /* ignore SIGPIPE */ 1783 signal(SIGPIPE, SIG_IGN); 1784 1785 /* Get a connection, either from inetd or a listening TCP socket */ 1786 if (inetd_flag) { 1787 server_accept_inetd(&sock_in, &sock_out); 1788 } else { 1789 platform_pre_listen(); 1790 server_listen(); 1791 1792 if (options.protocol & SSH_PROTO_1) 1793 generate_ephemeral_server_key(); 1794 1795 signal(SIGHUP, sighup_handler); 1796 signal(SIGCHLD, main_sigchld_handler); 1797 signal(SIGTERM, sigterm_handler); 1798 signal(SIGQUIT, sigterm_handler); 1799 1800 /* 1801 * Write out the pid file after the sigterm handler 1802 * is setup and the listen sockets are bound 1803 */ 1804 if (!debug_flag) { 1805 FILE *f = fopen(options.pid_file, "w"); 1806 1807 if (f == NULL) { 1808 error("Couldn't create pid file \"%s\": %s", 1809 options.pid_file, strerror(errno)); 1810 } else { 1811 fprintf(f, "%ld\n", (long) getpid()); 1812 fclose(f); 1813 } 1814 } 1815 1816 /* Accept a connection and return in a forked child */ 1817 server_accept_loop(&sock_in, &sock_out, 1818 &newsock, config_s); 1819 } 1820 1821 /* This is the child processing a new connection. */ 1822 setproctitle("%s", "[accepted]"); 1823 1824 /* 1825 * Initialize the resolver. This may not happen automatically 1826 * before privsep chroot(). 1827 */ 1828 if ((_res.options & RES_INIT) == 0) { 1829 debug("res_init()"); 1830 res_init(); 1831 } 1832 1833 /* 1834 * Create a new session and process group since the 4.4BSD 1835 * setlogin() affects the entire process group. We don't 1836 * want the child to be able to affect the parent. 1837 */ 1838 #if !defined(SSHD_ACQUIRES_CTTY) 1839 /* 1840 * If setsid is called, on some platforms sshd will later acquire a 1841 * controlling terminal which will result in "could not set 1842 * controlling tty" errors. 1843 */ 1844 if (!debug_flag && !inetd_flag && setsid() < 0) 1845 error("setsid: %.100s", strerror(errno)); 1846 #endif 1847 1848 if (rexec_flag) { 1849 int fd; 1850 1851 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1852 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1853 dup2(newsock, STDIN_FILENO); 1854 dup2(STDIN_FILENO, STDOUT_FILENO); 1855 if (startup_pipe == -1) 1856 close(REEXEC_STARTUP_PIPE_FD); 1857 else 1858 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1859 1860 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1861 close(config_s[1]); 1862 if (startup_pipe != -1) 1863 close(startup_pipe); 1864 1865 execv(rexec_argv[0], rexec_argv); 1866 1867 /* Reexec has failed, fall back and continue */ 1868 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1869 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1870 log_init(__progname, options.log_level, 1871 options.log_facility, log_stderr); 1872 1873 /* Clean up fds */ 1874 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1875 close(config_s[1]); 1876 close(REEXEC_CONFIG_PASS_FD); 1877 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1878 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1879 dup2(fd, STDIN_FILENO); 1880 dup2(fd, STDOUT_FILENO); 1881 if (fd > STDERR_FILENO) 1882 close(fd); 1883 } 1884 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1885 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1886 } 1887 1888 /* Executed child processes don't need these. */ 1889 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1890 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1891 1892 /* 1893 * Disable the key regeneration alarm. We will not regenerate the 1894 * key since we are no longer in a position to give it to anyone. We 1895 * will not restart on SIGHUP since it no longer makes sense. 1896 */ 1897 alarm(0); 1898 signal(SIGALRM, SIG_DFL); 1899 signal(SIGHUP, SIG_DFL); 1900 signal(SIGTERM, SIG_DFL); 1901 signal(SIGQUIT, SIG_DFL); 1902 signal(SIGCHLD, SIG_DFL); 1903 signal(SIGINT, SIG_DFL); 1904 1905 /* 1906 * Register our connection. This turns encryption off because we do 1907 * not have a key. 1908 */ 1909 packet_set_connection(sock_in, sock_out); 1910 packet_set_server(); 1911 1912 /* Set SO_KEEPALIVE if requested. */ 1913 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1914 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1915 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1916 1917 if ((remote_port = get_remote_port()) < 0) { 1918 debug("get_remote_port failed"); 1919 cleanup_exit(255); 1920 } 1921 1922 /* 1923 * We use get_canonical_hostname with usedns = 0 instead of 1924 * get_remote_ipaddr here so IP options will be checked. 1925 */ 1926 (void) get_canonical_hostname(0); 1927 /* 1928 * The rest of the code depends on the fact that 1929 * get_remote_ipaddr() caches the remote ip, even if 1930 * the socket goes away. 1931 */ 1932 remote_ip = get_remote_ipaddr(); 1933 1934 #ifdef SSH_AUDIT_EVENTS 1935 audit_connection_from(remote_ip, remote_port); 1936 #endif 1937 #ifdef LIBWRAP 1938 allow_severity = options.log_facility|LOG_INFO; 1939 deny_severity = options.log_facility|LOG_WARNING; 1940 /* Check whether logins are denied from this host. */ 1941 if (packet_connection_is_on_socket()) { 1942 struct request_info req; 1943 1944 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 1945 fromhost(&req); 1946 1947 if (!hosts_access(&req)) { 1948 debug("Connection refused by tcp wrapper"); 1949 refuse(&req); 1950 /* NOTREACHED */ 1951 fatal("libwrap refuse returns"); 1952 } 1953 } 1954 #endif /* LIBWRAP */ 1955 1956 /* Log the connection. */ 1957 verbose("Connection from %.500s port %d", remote_ip, remote_port); 1958 1959 /* set the HPN options for the child */ 1960 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size); 1961 1962 /* 1963 * We don't want to listen forever unless the other side 1964 * successfully authenticates itself. So we set up an alarm which is 1965 * cleared after successful authentication. A limit of zero 1966 * indicates no limit. Note that we don't set the alarm in debugging 1967 * mode; it is just annoying to have the server exit just when you 1968 * are about to discover the bug. 1969 */ 1970 signal(SIGALRM, grace_alarm_handler); 1971 if (!debug_flag) 1972 alarm(options.login_grace_time); 1973 1974 sshd_exchange_identification(sock_in, sock_out); 1975 1976 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 1977 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 1978 generate_ephemeral_server_key(); 1979 1980 packet_set_nonblocking(); 1981 1982 /* allocate authentication context */ 1983 authctxt = xcalloc(1, sizeof(*authctxt)); 1984 1985 authctxt->loginmsg = &loginmsg; 1986 1987 /* XXX global for cleanup, access from other modules */ 1988 the_authctxt = authctxt; 1989 1990 /* prepare buffer to collect messages to display to user after login */ 1991 buffer_init(&loginmsg); 1992 auth_debug_reset(); 1993 1994 if (use_privsep) 1995 if (privsep_preauth(authctxt) == 1) 1996 goto authenticated; 1997 1998 /* perform the key exchange */ 1999 /* authenticate user and start session */ 2000 if (compat20) { 2001 do_ssh2_kex(); 2002 do_authentication2(authctxt); 2003 } else { 2004 do_ssh1_kex(); 2005 do_authentication(authctxt); 2006 } 2007 /* 2008 * If we use privilege separation, the unprivileged child transfers 2009 * the current keystate and exits 2010 */ 2011 if (use_privsep) { 2012 mm_send_keystate(pmonitor); 2013 exit(0); 2014 } 2015 2016 authenticated: 2017 /* 2018 * Cancel the alarm we set to limit the time taken for 2019 * authentication. 2020 */ 2021 alarm(0); 2022 signal(SIGALRM, SIG_DFL); 2023 authctxt->authenticated = 1; 2024 if (startup_pipe != -1) { 2025 close(startup_pipe); 2026 startup_pipe = -1; 2027 } 2028 2029 #ifdef SSH_AUDIT_EVENTS 2030 audit_event(SSH_AUTH_SUCCESS); 2031 #endif 2032 2033 #ifdef GSSAPI 2034 if (options.gss_authentication) { 2035 temporarily_use_uid(authctxt->pw); 2036 ssh_gssapi_storecreds(); 2037 restore_uid(); 2038 } 2039 #endif 2040 #ifdef USE_PAM 2041 if (options.use_pam) { 2042 do_pam_setcred(1); 2043 do_pam_session(); 2044 } 2045 #endif 2046 2047 /* 2048 * In privilege separation, we fork another child and prepare 2049 * file descriptor passing. 2050 */ 2051 if (use_privsep) { 2052 privsep_postauth(authctxt); 2053 /* the monitor process [priv] will not return */ 2054 if (!compat20) 2055 destroy_sensitive_data(); 2056 } 2057 2058 packet_set_timeout(options.client_alive_interval, 2059 options.client_alive_count_max); 2060 2061 /* Start session. */ 2062 do_authenticated(authctxt); 2063 2064 /* The connection has been terminated. */ 2065 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 2066 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 2067 verbose("Transferred: sent %ju, received %ju bytes", 2068 (uintmax_t)obytes, (uintmax_t)ibytes); 2069 2070 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2071 2072 #ifdef USE_PAM 2073 if (options.use_pam) 2074 finish_pam(); 2075 #endif /* USE_PAM */ 2076 2077 #ifdef SSH_AUDIT_EVENTS 2078 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2079 #endif 2080 2081 packet_close(); 2082 2083 if (use_privsep) 2084 mm_terminate(); 2085 2086 exit(0); 2087 } 2088 2089 /* 2090 * Decrypt session_key_int using our private server key and private host key 2091 * (key with larger modulus first). 2092 */ 2093 int 2094 ssh1_session_key(BIGNUM *session_key_int) 2095 { 2096 int rsafail = 0; 2097 2098 if (BN_cmp(sensitive_data.server_key->rsa->n, 2099 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2100 /* Server key has bigger modulus. */ 2101 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2102 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2103 SSH_KEY_BITS_RESERVED) { 2104 fatal("do_connection: %s: " 2105 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2106 get_remote_ipaddr(), 2107 BN_num_bits(sensitive_data.server_key->rsa->n), 2108 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2109 SSH_KEY_BITS_RESERVED); 2110 } 2111 if (rsa_private_decrypt(session_key_int, session_key_int, 2112 sensitive_data.server_key->rsa) <= 0) 2113 rsafail++; 2114 if (rsa_private_decrypt(session_key_int, session_key_int, 2115 sensitive_data.ssh1_host_key->rsa) <= 0) 2116 rsafail++; 2117 } else { 2118 /* Host key has bigger modulus (or they are equal). */ 2119 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2120 BN_num_bits(sensitive_data.server_key->rsa->n) + 2121 SSH_KEY_BITS_RESERVED) { 2122 fatal("do_connection: %s: " 2123 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2124 get_remote_ipaddr(), 2125 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2126 BN_num_bits(sensitive_data.server_key->rsa->n), 2127 SSH_KEY_BITS_RESERVED); 2128 } 2129 if (rsa_private_decrypt(session_key_int, session_key_int, 2130 sensitive_data.ssh1_host_key->rsa) < 0) 2131 rsafail++; 2132 if (rsa_private_decrypt(session_key_int, session_key_int, 2133 sensitive_data.server_key->rsa) < 0) 2134 rsafail++; 2135 } 2136 return (rsafail); 2137 } 2138 /* 2139 * SSH1 key exchange 2140 */ 2141 static void 2142 do_ssh1_kex(void) 2143 { 2144 int i, len; 2145 int rsafail = 0; 2146 BIGNUM *session_key_int; 2147 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2148 u_char cookie[8]; 2149 u_int cipher_type, auth_mask, protocol_flags; 2150 2151 /* 2152 * Generate check bytes that the client must send back in the user 2153 * packet in order for it to be accepted; this is used to defy ip 2154 * spoofing attacks. Note that this only works against somebody 2155 * doing IP spoofing from a remote machine; any machine on the local 2156 * network can still see outgoing packets and catch the random 2157 * cookie. This only affects rhosts authentication, and this is one 2158 * of the reasons why it is inherently insecure. 2159 */ 2160 arc4random_buf(cookie, sizeof(cookie)); 2161 2162 /* 2163 * Send our public key. We include in the packet 64 bits of random 2164 * data that must be matched in the reply in order to prevent IP 2165 * spoofing. 2166 */ 2167 packet_start(SSH_SMSG_PUBLIC_KEY); 2168 for (i = 0; i < 8; i++) 2169 packet_put_char(cookie[i]); 2170 2171 /* Store our public server RSA key. */ 2172 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2173 packet_put_bignum(sensitive_data.server_key->rsa->e); 2174 packet_put_bignum(sensitive_data.server_key->rsa->n); 2175 2176 /* Store our public host RSA key. */ 2177 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2178 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2179 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2180 2181 /* Put protocol flags. */ 2182 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2183 2184 /* Declare which ciphers we support. */ 2185 packet_put_int(cipher_mask_ssh1(0)); 2186 2187 /* Declare supported authentication types. */ 2188 auth_mask = 0; 2189 if (options.rhosts_rsa_authentication) 2190 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2191 if (options.rsa_authentication) 2192 auth_mask |= 1 << SSH_AUTH_RSA; 2193 if (options.challenge_response_authentication == 1) 2194 auth_mask |= 1 << SSH_AUTH_TIS; 2195 if (options.password_authentication) 2196 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2197 packet_put_int(auth_mask); 2198 2199 /* Send the packet and wait for it to be sent. */ 2200 packet_send(); 2201 packet_write_wait(); 2202 2203 debug("Sent %d bit server key and %d bit host key.", 2204 BN_num_bits(sensitive_data.server_key->rsa->n), 2205 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2206 2207 /* Read clients reply (cipher type and session key). */ 2208 packet_read_expect(SSH_CMSG_SESSION_KEY); 2209 2210 /* Get cipher type and check whether we accept this. */ 2211 cipher_type = packet_get_char(); 2212 2213 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2214 packet_disconnect("Warning: client selects unsupported cipher."); 2215 2216 /* Get check bytes from the packet. These must match those we 2217 sent earlier with the public key packet. */ 2218 for (i = 0; i < 8; i++) 2219 if (cookie[i] != packet_get_char()) 2220 packet_disconnect("IP Spoofing check bytes do not match."); 2221 2222 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2223 2224 /* Get the encrypted integer. */ 2225 if ((session_key_int = BN_new()) == NULL) 2226 fatal("do_ssh1_kex: BN_new failed"); 2227 packet_get_bignum(session_key_int); 2228 2229 protocol_flags = packet_get_int(); 2230 packet_set_protocol_flags(protocol_flags); 2231 packet_check_eom(); 2232 2233 /* Decrypt session_key_int using host/server keys */ 2234 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2235 2236 /* 2237 * Extract session key from the decrypted integer. The key is in the 2238 * least significant 256 bits of the integer; the first byte of the 2239 * key is in the highest bits. 2240 */ 2241 if (!rsafail) { 2242 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2243 len = BN_num_bytes(session_key_int); 2244 if (len < 0 || (u_int)len > sizeof(session_key)) { 2245 error("do_ssh1_kex: bad session key len from %s: " 2246 "session_key_int %d > sizeof(session_key) %lu", 2247 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2248 rsafail++; 2249 } else { 2250 memset(session_key, 0, sizeof(session_key)); 2251 BN_bn2bin(session_key_int, 2252 session_key + sizeof(session_key) - len); 2253 2254 derive_ssh1_session_id( 2255 sensitive_data.ssh1_host_key->rsa->n, 2256 sensitive_data.server_key->rsa->n, 2257 cookie, session_id); 2258 /* 2259 * Xor the first 16 bytes of the session key with the 2260 * session id. 2261 */ 2262 for (i = 0; i < 16; i++) 2263 session_key[i] ^= session_id[i]; 2264 } 2265 } 2266 if (rsafail) { 2267 int bytes = BN_num_bytes(session_key_int); 2268 u_char *buf = xmalloc(bytes); 2269 MD5_CTX md; 2270 2271 logit("do_connection: generating a fake encryption key"); 2272 BN_bn2bin(session_key_int, buf); 2273 MD5_Init(&md); 2274 MD5_Update(&md, buf, bytes); 2275 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2276 MD5_Final(session_key, &md); 2277 MD5_Init(&md); 2278 MD5_Update(&md, session_key, 16); 2279 MD5_Update(&md, buf, bytes); 2280 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2281 MD5_Final(session_key + 16, &md); 2282 memset(buf, 0, bytes); 2283 xfree(buf); 2284 for (i = 0; i < 16; i++) 2285 session_id[i] = session_key[i] ^ session_key[i + 16]; 2286 } 2287 /* Destroy the private and public keys. No longer. */ 2288 destroy_sensitive_data(); 2289 2290 if (use_privsep) 2291 mm_ssh1_session_id(session_id); 2292 2293 /* Destroy the decrypted integer. It is no longer needed. */ 2294 BN_clear_free(session_key_int); 2295 2296 /* Set the session key. From this on all communications will be encrypted. */ 2297 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2298 2299 /* Destroy our copy of the session key. It is no longer needed. */ 2300 memset(session_key, 0, sizeof(session_key)); 2301 2302 debug("Received session key; encryption turned on."); 2303 2304 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2305 packet_start(SSH_SMSG_SUCCESS); 2306 packet_send(); 2307 packet_write_wait(); 2308 } 2309 2310 /* 2311 * SSH2 key exchange: diffie-hellman-group1-sha1 2312 */ 2313 static void 2314 do_ssh2_kex(void) 2315 { 2316 Kex *kex; 2317 2318 myflag++; 2319 debug ("MYFLAG IS %d", myflag); 2320 if (options.ciphers != NULL) { 2321 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2322 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2323 } else if (options.none_enabled == 1) { 2324 debug ("WARNING: None cipher enabled"); 2325 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2326 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE; 2327 } 2328 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2329 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2330 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2331 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2332 2333 if (options.macs != NULL) { 2334 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2335 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2336 } 2337 if (options.compression == COMP_NONE) { 2338 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2339 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2340 } else if (options.compression == COMP_DELAYED) { 2341 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2342 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2343 } 2344 2345 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); 2346 2347 /* start key exchange */ 2348 kex = kex_setup(myproposal); 2349 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2350 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2351 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2352 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2353 kex->server = 1; 2354 kex->client_version_string=client_version_string; 2355 kex->server_version_string=server_version_string; 2356 kex->load_host_public_key=&get_hostkey_public_by_type; 2357 kex->load_host_private_key=&get_hostkey_private_by_type; 2358 kex->host_key_index=&get_hostkey_index; 2359 2360 xxx_kex = kex; 2361 2362 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2363 2364 session_id2 = kex->session_id; 2365 session_id2_len = kex->session_id_len; 2366 2367 #ifdef DEBUG_KEXDH 2368 /* send 1st encrypted/maced/compressed message */ 2369 packet_start(SSH2_MSG_IGNORE); 2370 packet_put_cstring("markus"); 2371 packet_send(); 2372 packet_write_wait(); 2373 #endif 2374 debug("KEX done"); 2375 } 2376 2377 /* server specific fatal cleanup */ 2378 void 2379 cleanup_exit(int i) 2380 { 2381 if (the_authctxt) 2382 do_cleanup(the_authctxt); 2383 #ifdef SSH_AUDIT_EVENTS 2384 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2385 if (!use_privsep || mm_is_monitor()) 2386 audit_event(SSH_CONNECTION_ABANDON); 2387 #endif 2388 _exit(i); 2389 } 2390