1 /* $OpenBSD: sshd.c,v 1.381 2011/01/11 06:13:10 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 __RCSID("$FreeBSD$"); 47 48 #include <sys/types.h> 49 #include <sys/ioctl.h> 50 #include <sys/mman.h> 51 #include <sys/socket.h> 52 #ifdef HAVE_SYS_STAT_H 53 # include <sys/stat.h> 54 #endif 55 #ifdef HAVE_SYS_TIME_H 56 # include <sys/time.h> 57 #endif 58 #include "openbsd-compat/sys-tree.h" 59 #include "openbsd-compat/sys-queue.h" 60 #include <sys/wait.h> 61 62 #include <errno.h> 63 #include <fcntl.h> 64 #include <netdb.h> 65 #ifdef HAVE_PATHS_H 66 #include <paths.h> 67 #endif 68 #include <grp.h> 69 #include <pwd.h> 70 #include <signal.h> 71 #include <stdarg.h> 72 #include <stdio.h> 73 #include <stdlib.h> 74 #include <string.h> 75 #include <unistd.h> 76 77 #include <openssl/dh.h> 78 #include <openssl/bn.h> 79 #include <openssl/md5.h> 80 #include <openssl/rand.h> 81 #include "openbsd-compat/openssl-compat.h" 82 83 #ifdef HAVE_SECUREWARE 84 #include <sys/security.h> 85 #include <prot.h> 86 #endif 87 88 #ifdef __FreeBSD__ 89 #include <resolv.h> 90 #if defined(GSSAPI) && defined(HAVE_GSSAPI_H) 91 #include <gssapi.h> 92 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H) 93 #include <gssapi/gssapi.h> 94 #endif 95 #endif 96 97 #include "xmalloc.h" 98 #include "ssh.h" 99 #include "ssh1.h" 100 #include "ssh2.h" 101 #include "rsa.h" 102 #include "sshpty.h" 103 #include "packet.h" 104 #include "log.h" 105 #include "buffer.h" 106 #include "servconf.h" 107 #include "uidswap.h" 108 #include "compat.h" 109 #include "cipher.h" 110 #include "key.h" 111 #include "kex.h" 112 #include "dh.h" 113 #include "myproposal.h" 114 #include "authfile.h" 115 #include "pathnames.h" 116 #include "atomicio.h" 117 #include "canohost.h" 118 #include "hostfile.h" 119 #include "auth.h" 120 #include "misc.h" 121 #include "msg.h" 122 #include "dispatch.h" 123 #include "channels.h" 124 #include "session.h" 125 #include "monitor_mm.h" 126 #include "monitor.h" 127 #ifdef GSSAPI 128 #include "ssh-gss.h" 129 #endif 130 #include "monitor_wrap.h" 131 #include "roaming.h" 132 #include "version.h" 133 134 #ifdef LIBWRAP 135 #include <tcpd.h> 136 #include <syslog.h> 137 int allow_severity; 138 int deny_severity; 139 #endif /* LIBWRAP */ 140 141 #ifndef O_NOCTTY 142 #define O_NOCTTY 0 143 #endif 144 145 /* Re-exec fds */ 146 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 147 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 148 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 149 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 150 151 extern char *__progname; 152 153 /* Server configuration options. */ 154 ServerOptions options; 155 156 /* Name of the server configuration file. */ 157 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 158 159 /* 160 * Debug mode flag. This can be set on the command line. If debug 161 * mode is enabled, extra debugging output will be sent to the system 162 * log, the daemon will not go to background, and will exit after processing 163 * the first connection. 164 */ 165 int debug_flag = 0; 166 167 /* Flag indicating that the daemon should only test the configuration and keys. */ 168 int test_flag = 0; 169 170 /* Flag indicating that the daemon is being started from inetd. */ 171 int inetd_flag = 0; 172 173 /* Flag indicating that sshd should not detach and become a daemon. */ 174 int no_daemon_flag = 0; 175 176 /* debug goes to stderr unless inetd_flag is set */ 177 int log_stderr = 0; 178 179 /* Saved arguments to main(). */ 180 char **saved_argv; 181 int saved_argc; 182 183 /* re-exec */ 184 int rexeced_flag = 0; 185 int rexec_flag = 1; 186 int rexec_argc = 0; 187 char **rexec_argv; 188 189 /* 190 * The sockets that the server is listening; this is used in the SIGHUP 191 * signal handler. 192 */ 193 #define MAX_LISTEN_SOCKS 16 194 int listen_socks[MAX_LISTEN_SOCKS]; 195 int num_listen_socks = 0; 196 197 /* 198 * the client's version string, passed by sshd2 in compat mode. if != NULL, 199 * sshd will skip the version-number exchange 200 */ 201 char *client_version_string = NULL; 202 char *server_version_string = NULL; 203 204 /* for rekeying XXX fixme */ 205 Kex *xxx_kex; 206 207 /* 208 * Any really sensitive data in the application is contained in this 209 * structure. The idea is that this structure could be locked into memory so 210 * that the pages do not get written into swap. However, there are some 211 * problems. The private key contains BIGNUMs, and we do not (in principle) 212 * have access to the internals of them, and locking just the structure is 213 * not very useful. Currently, memory locking is not implemented. 214 */ 215 struct { 216 Key *server_key; /* ephemeral server key */ 217 Key *ssh1_host_key; /* ssh1 host key */ 218 Key **host_keys; /* all private host keys */ 219 Key **host_certificates; /* all public host certificates */ 220 int have_ssh1_key; 221 int have_ssh2_key; 222 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 223 } sensitive_data; 224 225 /* 226 * Flag indicating whether the RSA server key needs to be regenerated. 227 * Is set in the SIGALRM handler and cleared when the key is regenerated. 228 */ 229 static volatile sig_atomic_t key_do_regen = 0; 230 231 /* This is set to true when a signal is received. */ 232 static volatile sig_atomic_t received_sighup = 0; 233 static volatile sig_atomic_t received_sigterm = 0; 234 235 /* session identifier, used by RSA-auth */ 236 u_char session_id[16]; 237 238 /* same for ssh2 */ 239 u_char *session_id2 = NULL; 240 u_int session_id2_len = 0; 241 242 /* record remote hostname or ip */ 243 u_int utmp_len = MAXHOSTNAMELEN; 244 245 /* options.max_startup sized array of fd ints */ 246 int *startup_pipes = NULL; 247 int startup_pipe; /* in child */ 248 249 /* variables used for privilege separation */ 250 int use_privsep = -1; 251 struct monitor *pmonitor = NULL; 252 253 /* global authentication context */ 254 Authctxt *the_authctxt = NULL; 255 256 /* sshd_config buffer */ 257 Buffer cfg; 258 259 /* message to be displayed after login */ 260 Buffer loginmsg; 261 262 /* Unprivileged user */ 263 struct passwd *privsep_pw = NULL; 264 265 /* Prototypes for various functions defined later in this file. */ 266 void destroy_sensitive_data(void); 267 void demote_sensitive_data(void); 268 269 static void do_ssh1_kex(void); 270 static void do_ssh2_kex(void); 271 272 /* 273 * Close all listening sockets 274 */ 275 static void 276 close_listen_socks(void) 277 { 278 int i; 279 280 for (i = 0; i < num_listen_socks; i++) 281 close(listen_socks[i]); 282 num_listen_socks = -1; 283 } 284 285 static void 286 close_startup_pipes(void) 287 { 288 int i; 289 290 if (startup_pipes) 291 for (i = 0; i < options.max_startups; i++) 292 if (startup_pipes[i] != -1) 293 close(startup_pipes[i]); 294 } 295 296 /* 297 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 298 * the effect is to reread the configuration file (and to regenerate 299 * the server key). 300 */ 301 302 /*ARGSUSED*/ 303 static void 304 sighup_handler(int sig) 305 { 306 int save_errno = errno; 307 308 received_sighup = 1; 309 signal(SIGHUP, sighup_handler); 310 errno = save_errno; 311 } 312 313 /* 314 * Called from the main program after receiving SIGHUP. 315 * Restarts the server. 316 */ 317 static void 318 sighup_restart(void) 319 { 320 logit("Received SIGHUP; restarting."); 321 close_listen_socks(); 322 close_startup_pipes(); 323 alarm(0); /* alarm timer persists across exec */ 324 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 325 execv(saved_argv[0], saved_argv); 326 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 327 strerror(errno)); 328 exit(1); 329 } 330 331 /* 332 * Generic signal handler for terminating signals in the master daemon. 333 */ 334 /*ARGSUSED*/ 335 static void 336 sigterm_handler(int sig) 337 { 338 received_sigterm = sig; 339 } 340 341 /* 342 * SIGCHLD handler. This is called whenever a child dies. This will then 343 * reap any zombies left by exited children. 344 */ 345 /*ARGSUSED*/ 346 static void 347 main_sigchld_handler(int sig) 348 { 349 int save_errno = errno; 350 pid_t pid; 351 int status; 352 353 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 354 (pid < 0 && errno == EINTR)) 355 ; 356 357 signal(SIGCHLD, main_sigchld_handler); 358 errno = save_errno; 359 } 360 361 /* 362 * Signal handler for the alarm after the login grace period has expired. 363 */ 364 /*ARGSUSED*/ 365 static void 366 grace_alarm_handler(int sig) 367 { 368 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 369 kill(pmonitor->m_pid, SIGALRM); 370 371 /* Log error and exit. */ 372 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 373 } 374 375 /* 376 * Signal handler for the key regeneration alarm. Note that this 377 * alarm only occurs in the daemon waiting for connections, and it does not 378 * do anything with the private key or random state before forking. 379 * Thus there should be no concurrency control/asynchronous execution 380 * problems. 381 */ 382 static void 383 generate_ephemeral_server_key(void) 384 { 385 verbose("Generating %s%d bit RSA key.", 386 sensitive_data.server_key ? "new " : "", options.server_key_bits); 387 if (sensitive_data.server_key != NULL) 388 key_free(sensitive_data.server_key); 389 sensitive_data.server_key = key_generate(KEY_RSA1, 390 options.server_key_bits); 391 verbose("RSA key generation complete."); 392 393 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 394 arc4random_stir(); 395 } 396 397 /*ARGSUSED*/ 398 static void 399 key_regeneration_alarm(int sig) 400 { 401 int save_errno = errno; 402 403 signal(SIGALRM, SIG_DFL); 404 errno = save_errno; 405 key_do_regen = 1; 406 } 407 408 static void 409 sshd_exchange_identification(int sock_in, int sock_out) 410 { 411 u_int i; 412 int mismatch; 413 int remote_major, remote_minor; 414 int major, minor; 415 char *s, *newline = "\n"; 416 char buf[256]; /* Must not be larger than remote_version. */ 417 char remote_version[256]; /* Must be at least as big as buf. */ 418 419 if ((options.protocol & SSH_PROTO_1) && 420 (options.protocol & SSH_PROTO_2)) { 421 major = PROTOCOL_MAJOR_1; 422 minor = 99; 423 } else if (options.protocol & SSH_PROTO_2) { 424 major = PROTOCOL_MAJOR_2; 425 minor = PROTOCOL_MINOR_2; 426 newline = "\r\n"; 427 } else { 428 major = PROTOCOL_MAJOR_1; 429 minor = PROTOCOL_MINOR_1; 430 } 431 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor, 432 SSH_VERSION, newline); 433 server_version_string = xstrdup(buf); 434 435 /* Send our protocol version identification. */ 436 if (roaming_atomicio(vwrite, sock_out, server_version_string, 437 strlen(server_version_string)) 438 != strlen(server_version_string)) { 439 logit("Could not write ident string to %s", get_remote_ipaddr()); 440 cleanup_exit(255); 441 } 442 443 /* Read other sides version identification. */ 444 memset(buf, 0, sizeof(buf)); 445 for (i = 0; i < sizeof(buf) - 1; i++) { 446 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 447 logit("Did not receive identification string from %s", 448 get_remote_ipaddr()); 449 cleanup_exit(255); 450 } 451 if (buf[i] == '\r') { 452 buf[i] = 0; 453 /* Kludge for F-Secure Macintosh < 1.0.2 */ 454 if (i == 12 && 455 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 456 break; 457 continue; 458 } 459 if (buf[i] == '\n') { 460 buf[i] = 0; 461 break; 462 } 463 } 464 buf[sizeof(buf) - 1] = 0; 465 client_version_string = xstrdup(buf); 466 467 /* 468 * Check that the versions match. In future this might accept 469 * several versions and set appropriate flags to handle them. 470 */ 471 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 472 &remote_major, &remote_minor, remote_version) != 3) { 473 s = "Protocol mismatch.\n"; 474 (void) atomicio(vwrite, sock_out, s, strlen(s)); 475 close(sock_in); 476 close(sock_out); 477 logit("Bad protocol version identification '%.100s' from %s", 478 client_version_string, get_remote_ipaddr()); 479 cleanup_exit(255); 480 } 481 debug("Client protocol version %d.%d; client software version %.100s", 482 remote_major, remote_minor, remote_version); 483 484 compat_datafellows(remote_version); 485 486 if (datafellows & SSH_BUG_PROBE) { 487 logit("probed from %s with %s. Don't panic.", 488 get_remote_ipaddr(), client_version_string); 489 cleanup_exit(255); 490 } 491 492 if (datafellows & SSH_BUG_SCANNER) { 493 logit("scanned from %s with %s. Don't panic.", 494 get_remote_ipaddr(), client_version_string); 495 cleanup_exit(255); 496 } 497 498 mismatch = 0; 499 switch (remote_major) { 500 case 1: 501 if (remote_minor == 99) { 502 if (options.protocol & SSH_PROTO_2) 503 enable_compat20(); 504 else 505 mismatch = 1; 506 break; 507 } 508 if (!(options.protocol & SSH_PROTO_1)) { 509 mismatch = 1; 510 break; 511 } 512 if (remote_minor < 3) { 513 packet_disconnect("Your ssh version is too old and " 514 "is no longer supported. Please install a newer version."); 515 } else if (remote_minor == 3) { 516 /* note that this disables agent-forwarding */ 517 enable_compat13(); 518 } 519 break; 520 case 2: 521 if (options.protocol & SSH_PROTO_2) { 522 enable_compat20(); 523 break; 524 } 525 /* FALLTHROUGH */ 526 default: 527 mismatch = 1; 528 break; 529 } 530 chop(server_version_string); 531 debug("Local version string %.200s", server_version_string); 532 533 if (mismatch) { 534 s = "Protocol major versions differ.\n"; 535 (void) atomicio(vwrite, sock_out, s, strlen(s)); 536 close(sock_in); 537 close(sock_out); 538 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 539 get_remote_ipaddr(), 540 server_version_string, client_version_string); 541 cleanup_exit(255); 542 } 543 } 544 545 /* Destroy the host and server keys. They will no longer be needed. */ 546 void 547 destroy_sensitive_data(void) 548 { 549 int i; 550 551 if (sensitive_data.server_key) { 552 key_free(sensitive_data.server_key); 553 sensitive_data.server_key = NULL; 554 } 555 for (i = 0; i < options.num_host_key_files; i++) { 556 if (sensitive_data.host_keys[i]) { 557 key_free(sensitive_data.host_keys[i]); 558 sensitive_data.host_keys[i] = NULL; 559 } 560 if (sensitive_data.host_certificates[i]) { 561 key_free(sensitive_data.host_certificates[i]); 562 sensitive_data.host_certificates[i] = NULL; 563 } 564 } 565 sensitive_data.ssh1_host_key = NULL; 566 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); 567 } 568 569 /* Demote private to public keys for network child */ 570 void 571 demote_sensitive_data(void) 572 { 573 Key *tmp; 574 int i; 575 576 if (sensitive_data.server_key) { 577 tmp = key_demote(sensitive_data.server_key); 578 key_free(sensitive_data.server_key); 579 sensitive_data.server_key = tmp; 580 } 581 582 for (i = 0; i < options.num_host_key_files; i++) { 583 if (sensitive_data.host_keys[i]) { 584 tmp = key_demote(sensitive_data.host_keys[i]); 585 key_free(sensitive_data.host_keys[i]); 586 sensitive_data.host_keys[i] = tmp; 587 if (tmp->type == KEY_RSA1) 588 sensitive_data.ssh1_host_key = tmp; 589 } 590 /* Certs do not need demotion */ 591 } 592 593 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 594 } 595 596 static void 597 privsep_preauth_child(void) 598 { 599 u_int32_t rnd[256]; 600 gid_t gidset[1]; 601 602 /* Enable challenge-response authentication for privilege separation */ 603 privsep_challenge_enable(); 604 605 arc4random_stir(); 606 arc4random_buf(rnd, sizeof(rnd)); 607 RAND_seed(rnd, sizeof(rnd)); 608 609 /* Demote the private keys to public keys. */ 610 demote_sensitive_data(); 611 612 /* Change our root directory */ 613 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 614 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 615 strerror(errno)); 616 if (chdir("/") == -1) 617 fatal("chdir(\"/\"): %s", strerror(errno)); 618 619 /* Drop our privileges */ 620 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 621 (u_int)privsep_pw->pw_gid); 622 #if 0 623 /* XXX not ready, too heavy after chroot */ 624 do_setusercontext(privsep_pw); 625 #else 626 gidset[0] = privsep_pw->pw_gid; 627 if (setgroups(1, gidset) < 0) 628 fatal("setgroups: %.100s", strerror(errno)); 629 permanently_set_uid(privsep_pw); 630 #endif 631 } 632 633 static int 634 privsep_preauth(Authctxt *authctxt) 635 { 636 int status; 637 pid_t pid; 638 639 /* Set up unprivileged child process to deal with network data */ 640 pmonitor = monitor_init(); 641 /* Store a pointer to the kex for later rekeying */ 642 pmonitor->m_pkex = &xxx_kex; 643 644 pid = fork(); 645 if (pid == -1) { 646 fatal("fork of unprivileged child failed"); 647 } else if (pid != 0) { 648 debug2("Network child is on pid %ld", (long)pid); 649 650 close(pmonitor->m_recvfd); 651 pmonitor->m_pid = pid; 652 monitor_child_preauth(authctxt, pmonitor); 653 close(pmonitor->m_sendfd); 654 655 /* Sync memory */ 656 monitor_sync(pmonitor); 657 658 /* Wait for the child's exit status */ 659 while (waitpid(pid, &status, 0) < 0) 660 if (errno != EINTR) 661 break; 662 return (1); 663 } else { 664 /* child */ 665 666 close(pmonitor->m_sendfd); 667 668 /* Demote the child */ 669 if (getuid() == 0 || geteuid() == 0) 670 privsep_preauth_child(); 671 setproctitle("%s", "[net]"); 672 } 673 return (0); 674 } 675 676 static void 677 privsep_postauth(Authctxt *authctxt) 678 { 679 u_int32_t rnd[256]; 680 681 #ifdef DISABLE_FD_PASSING 682 if (1) { 683 #else 684 if (authctxt->pw->pw_uid == 0 || options.use_login) { 685 #endif 686 /* File descriptor passing is broken or root login */ 687 use_privsep = 0; 688 goto skip; 689 } 690 691 /* New socket pair */ 692 monitor_reinit(pmonitor); 693 694 pmonitor->m_pid = fork(); 695 if (pmonitor->m_pid == -1) 696 fatal("fork of unprivileged child failed"); 697 else if (pmonitor->m_pid != 0) { 698 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 699 close(pmonitor->m_recvfd); 700 buffer_clear(&loginmsg); 701 monitor_child_postauth(pmonitor); 702 703 /* NEVERREACHED */ 704 exit(0); 705 } 706 707 close(pmonitor->m_sendfd); 708 709 /* Demote the private keys to public keys. */ 710 demote_sensitive_data(); 711 712 arc4random_stir(); 713 arc4random_buf(rnd, sizeof(rnd)); 714 RAND_seed(rnd, sizeof(rnd)); 715 716 /* Drop privileges */ 717 do_setusercontext(authctxt->pw); 718 719 skip: 720 /* It is safe now to apply the key state */ 721 monitor_apply_keystate(pmonitor); 722 723 /* 724 * Tell the packet layer that authentication was successful, since 725 * this information is not part of the key state. 726 */ 727 packet_set_authenticated(); 728 } 729 730 static char * 731 list_hostkey_types(void) 732 { 733 Buffer b; 734 const char *p; 735 char *ret; 736 int i; 737 Key *key; 738 739 buffer_init(&b); 740 for (i = 0; i < options.num_host_key_files; i++) { 741 key = sensitive_data.host_keys[i]; 742 if (key == NULL) 743 continue; 744 switch (key->type) { 745 case KEY_RSA: 746 case KEY_DSA: 747 case KEY_ECDSA: 748 if (buffer_len(&b) > 0) 749 buffer_append(&b, ",", 1); 750 p = key_ssh_name(key); 751 buffer_append(&b, p, strlen(p)); 752 break; 753 } 754 /* If the private key has a cert peer, then list that too */ 755 key = sensitive_data.host_certificates[i]; 756 if (key == NULL) 757 continue; 758 switch (key->type) { 759 case KEY_RSA_CERT_V00: 760 case KEY_DSA_CERT_V00: 761 case KEY_RSA_CERT: 762 case KEY_DSA_CERT: 763 case KEY_ECDSA_CERT: 764 if (buffer_len(&b) > 0) 765 buffer_append(&b, ",", 1); 766 p = key_ssh_name(key); 767 buffer_append(&b, p, strlen(p)); 768 break; 769 } 770 } 771 buffer_append(&b, "\0", 1); 772 ret = xstrdup(buffer_ptr(&b)); 773 buffer_free(&b); 774 debug("list_hostkey_types: %s", ret); 775 return ret; 776 } 777 778 static Key * 779 get_hostkey_by_type(int type, int need_private) 780 { 781 int i; 782 Key *key; 783 784 for (i = 0; i < options.num_host_key_files; i++) { 785 switch (type) { 786 case KEY_RSA_CERT_V00: 787 case KEY_DSA_CERT_V00: 788 case KEY_RSA_CERT: 789 case KEY_DSA_CERT: 790 case KEY_ECDSA_CERT: 791 key = sensitive_data.host_certificates[i]; 792 break; 793 default: 794 key = sensitive_data.host_keys[i]; 795 break; 796 } 797 if (key != NULL && key->type == type) 798 return need_private ? 799 sensitive_data.host_keys[i] : key; 800 } 801 return NULL; 802 } 803 804 Key * 805 get_hostkey_public_by_type(int type) 806 { 807 return get_hostkey_by_type(type, 0); 808 } 809 810 Key * 811 get_hostkey_private_by_type(int type) 812 { 813 return get_hostkey_by_type(type, 1); 814 } 815 816 Key * 817 get_hostkey_by_index(int ind) 818 { 819 if (ind < 0 || ind >= options.num_host_key_files) 820 return (NULL); 821 return (sensitive_data.host_keys[ind]); 822 } 823 824 int 825 get_hostkey_index(Key *key) 826 { 827 int i; 828 829 for (i = 0; i < options.num_host_key_files; i++) { 830 if (key_is_cert(key)) { 831 if (key == sensitive_data.host_certificates[i]) 832 return (i); 833 } else { 834 if (key == sensitive_data.host_keys[i]) 835 return (i); 836 } 837 } 838 return (-1); 839 } 840 841 /* 842 * returns 1 if connection should be dropped, 0 otherwise. 843 * dropping starts at connection #max_startups_begin with a probability 844 * of (max_startups_rate/100). the probability increases linearly until 845 * all connections are dropped for startups > max_startups 846 */ 847 static int 848 drop_connection(int startups) 849 { 850 int p, r; 851 852 if (startups < options.max_startups_begin) 853 return 0; 854 if (startups >= options.max_startups) 855 return 1; 856 if (options.max_startups_rate == 100) 857 return 1; 858 859 p = 100 - options.max_startups_rate; 860 p *= startups - options.max_startups_begin; 861 p /= options.max_startups - options.max_startups_begin; 862 p += options.max_startups_rate; 863 r = arc4random_uniform(100); 864 865 debug("drop_connection: p %d, r %d", p, r); 866 return (r < p) ? 1 : 0; 867 } 868 869 static void 870 usage(void) 871 { 872 fprintf(stderr, "%s, %s\n", 873 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); 874 fprintf(stderr, 875 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 876 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n" 877 " [-k key_gen_time] [-o option] [-p port] [-u len]\n" 878 ); 879 exit(1); 880 } 881 882 static void 883 send_rexec_state(int fd, Buffer *conf) 884 { 885 Buffer m; 886 887 debug3("%s: entering fd = %d config len %d", __func__, fd, 888 buffer_len(conf)); 889 890 /* 891 * Protocol from reexec master to child: 892 * string configuration 893 * u_int ephemeral_key_follows 894 * bignum e (only if ephemeral_key_follows == 1) 895 * bignum n " 896 * bignum d " 897 * bignum iqmp " 898 * bignum p " 899 * bignum q " 900 * string rngseed (only if OpenSSL is not self-seeded) 901 */ 902 buffer_init(&m); 903 buffer_put_cstring(&m, buffer_ptr(conf)); 904 905 if (sensitive_data.server_key != NULL && 906 sensitive_data.server_key->type == KEY_RSA1) { 907 buffer_put_int(&m, 1); 908 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 909 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 910 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 911 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 912 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 913 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 914 } else 915 buffer_put_int(&m, 0); 916 917 #ifndef OPENSSL_PRNG_ONLY 918 rexec_send_rng_seed(&m); 919 #endif 920 921 if (ssh_msg_send(fd, 0, &m) == -1) 922 fatal("%s: ssh_msg_send failed", __func__); 923 924 buffer_free(&m); 925 926 debug3("%s: done", __func__); 927 } 928 929 static void 930 recv_rexec_state(int fd, Buffer *conf) 931 { 932 Buffer m; 933 char *cp; 934 u_int len; 935 936 debug3("%s: entering fd = %d", __func__, fd); 937 938 buffer_init(&m); 939 940 if (ssh_msg_recv(fd, &m) == -1) 941 fatal("%s: ssh_msg_recv failed", __func__); 942 if (buffer_get_char(&m) != 0) 943 fatal("%s: rexec version mismatch", __func__); 944 945 cp = buffer_get_string(&m, &len); 946 if (conf != NULL) 947 buffer_append(conf, cp, len + 1); 948 xfree(cp); 949 950 if (buffer_get_int(&m)) { 951 if (sensitive_data.server_key != NULL) 952 key_free(sensitive_data.server_key); 953 sensitive_data.server_key = key_new_private(KEY_RSA1); 954 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 955 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 956 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 957 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 958 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 959 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 960 rsa_generate_additional_parameters( 961 sensitive_data.server_key->rsa); 962 } 963 964 #ifndef OPENSSL_PRNG_ONLY 965 rexec_recv_rng_seed(&m); 966 #endif 967 968 buffer_free(&m); 969 970 debug3("%s: done", __func__); 971 } 972 973 /* Accept a connection from inetd */ 974 static void 975 server_accept_inetd(int *sock_in, int *sock_out) 976 { 977 int fd; 978 979 startup_pipe = -1; 980 if (rexeced_flag) { 981 close(REEXEC_CONFIG_PASS_FD); 982 *sock_in = *sock_out = dup(STDIN_FILENO); 983 if (!debug_flag) { 984 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 985 close(REEXEC_STARTUP_PIPE_FD); 986 } 987 } else { 988 *sock_in = dup(STDIN_FILENO); 989 *sock_out = dup(STDOUT_FILENO); 990 } 991 /* 992 * We intentionally do not close the descriptors 0, 1, and 2 993 * as our code for setting the descriptors won't work if 994 * ttyfd happens to be one of those. 995 */ 996 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 997 dup2(fd, STDIN_FILENO); 998 dup2(fd, STDOUT_FILENO); 999 if (fd > STDOUT_FILENO) 1000 close(fd); 1001 } 1002 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1003 } 1004 1005 /* 1006 * Listen for TCP connections 1007 */ 1008 static void 1009 server_listen(void) 1010 { 1011 int ret, listen_sock, on = 1; 1012 struct addrinfo *ai; 1013 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1014 1015 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1016 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1017 continue; 1018 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1019 fatal("Too many listen sockets. " 1020 "Enlarge MAX_LISTEN_SOCKS"); 1021 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1022 ntop, sizeof(ntop), strport, sizeof(strport), 1023 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1024 error("getnameinfo failed: %.100s", 1025 ssh_gai_strerror(ret)); 1026 continue; 1027 } 1028 /* Create socket for listening. */ 1029 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1030 ai->ai_protocol); 1031 if (listen_sock < 0) { 1032 /* kernel may not support ipv6 */ 1033 verbose("socket: %.100s", strerror(errno)); 1034 continue; 1035 } 1036 if (set_nonblock(listen_sock) == -1) { 1037 close(listen_sock); 1038 continue; 1039 } 1040 /* 1041 * Set socket options. 1042 * Allow local port reuse in TIME_WAIT. 1043 */ 1044 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1045 &on, sizeof(on)) == -1) 1046 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1047 1048 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1049 if (ai->ai_family == AF_INET6) 1050 sock_set_v6only(listen_sock); 1051 1052 debug("Bind to port %s on %s.", strport, ntop); 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 OpenSSL_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 sensitive_data.host_keys[i] = key; 1580 if (key == NULL) { 1581 error("Could not load host key: %s", 1582 options.host_key_files[i]); 1583 sensitive_data.host_keys[i] = NULL; 1584 continue; 1585 } 1586 switch (key->type) { 1587 case KEY_RSA1: 1588 sensitive_data.ssh1_host_key = key; 1589 sensitive_data.have_ssh1_key = 1; 1590 break; 1591 case KEY_RSA: 1592 case KEY_DSA: 1593 case KEY_ECDSA: 1594 sensitive_data.have_ssh2_key = 1; 1595 break; 1596 } 1597 debug("private host key: #%d type %d %s", i, key->type, 1598 key_type(key)); 1599 } 1600 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1601 logit("Disabling protocol version 1. Could not load host key"); 1602 options.protocol &= ~SSH_PROTO_1; 1603 } 1604 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1605 logit("Disabling protocol version 2. Could not load host key"); 1606 options.protocol &= ~SSH_PROTO_2; 1607 } 1608 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1609 logit("sshd: no hostkeys available -- exiting."); 1610 exit(1); 1611 } 1612 1613 /* 1614 * Load certificates. They are stored in an array at identical 1615 * indices to the public keys that they relate to. 1616 */ 1617 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1618 sizeof(Key *)); 1619 for (i = 0; i < options.num_host_key_files; i++) 1620 sensitive_data.host_certificates[i] = NULL; 1621 1622 for (i = 0; i < options.num_host_cert_files; i++) { 1623 key = key_load_public(options.host_cert_files[i], NULL); 1624 if (key == NULL) { 1625 error("Could not load host certificate: %s", 1626 options.host_cert_files[i]); 1627 continue; 1628 } 1629 if (!key_is_cert(key)) { 1630 error("Certificate file is not a certificate: %s", 1631 options.host_cert_files[i]); 1632 key_free(key); 1633 continue; 1634 } 1635 /* Find matching private key */ 1636 for (j = 0; j < options.num_host_key_files; j++) { 1637 if (key_equal_public(key, 1638 sensitive_data.host_keys[j])) { 1639 sensitive_data.host_certificates[j] = key; 1640 break; 1641 } 1642 } 1643 if (j >= options.num_host_key_files) { 1644 error("No matching private key for certificate: %s", 1645 options.host_cert_files[i]); 1646 key_free(key); 1647 continue; 1648 } 1649 sensitive_data.host_certificates[j] = key; 1650 debug("host certificate: #%d type %d %s", j, key->type, 1651 key_type(key)); 1652 } 1653 /* Check certain values for sanity. */ 1654 if (options.protocol & SSH_PROTO_1) { 1655 if (options.server_key_bits < 512 || 1656 options.server_key_bits > 32768) { 1657 fprintf(stderr, "Bad server key size.\n"); 1658 exit(1); 1659 } 1660 /* 1661 * Check that server and host key lengths differ sufficiently. This 1662 * is necessary to make double encryption work with rsaref. Oh, I 1663 * hate software patents. I dont know if this can go? Niels 1664 */ 1665 if (options.server_key_bits > 1666 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1667 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1668 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1669 SSH_KEY_BITS_RESERVED) { 1670 options.server_key_bits = 1671 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1672 SSH_KEY_BITS_RESERVED; 1673 debug("Forcing server key to %d bits to make it differ from host key.", 1674 options.server_key_bits); 1675 } 1676 } 1677 1678 if (use_privsep) { 1679 struct stat st; 1680 1681 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1682 (S_ISDIR(st.st_mode) == 0)) 1683 fatal("Missing privilege separation directory: %s", 1684 _PATH_PRIVSEP_CHROOT_DIR); 1685 1686 #ifdef HAVE_CYGWIN 1687 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1688 (st.st_uid != getuid () || 1689 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1690 #else 1691 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1692 #endif 1693 fatal("%s must be owned by root and not group or " 1694 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1695 } 1696 1697 if (test_flag > 1) { 1698 if (test_user != NULL && test_addr != NULL && test_host != NULL) 1699 parse_server_match_config(&options, test_user, 1700 test_host, test_addr); 1701 dump_config(&options); 1702 } 1703 1704 /* Configuration looks good, so exit if in test mode. */ 1705 if (test_flag) 1706 exit(0); 1707 1708 /* 1709 * Clear out any supplemental groups we may have inherited. This 1710 * prevents inadvertent creation of files with bad modes (in the 1711 * portable version at least, it's certainly possible for PAM 1712 * to create a file, and we can't control the code in every 1713 * module which might be used). 1714 */ 1715 if (setgroups(0, NULL) < 0) 1716 debug("setgroups() failed: %.200s", strerror(errno)); 1717 1718 if (rexec_flag) { 1719 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1720 for (i = 0; i < rexec_argc; i++) { 1721 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1722 rexec_argv[i] = saved_argv[i]; 1723 } 1724 rexec_argv[rexec_argc] = "-R"; 1725 rexec_argv[rexec_argc + 1] = NULL; 1726 } 1727 1728 /* Ensure that umask disallows at least group and world write */ 1729 new_umask = umask(0077) | 0022; 1730 (void) umask(new_umask); 1731 1732 /* Initialize the log (it is reinitialized below in case we forked). */ 1733 if (debug_flag && (!inetd_flag || rexeced_flag)) 1734 log_stderr = 1; 1735 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1736 1737 /* 1738 * If not in debugging mode, and not started from inetd, disconnect 1739 * from the controlling terminal, and fork. The original process 1740 * exits. 1741 */ 1742 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1743 #ifdef TIOCNOTTY 1744 int fd; 1745 #endif /* TIOCNOTTY */ 1746 if (daemon(0, 0) < 0) 1747 fatal("daemon() failed: %.200s", strerror(errno)); 1748 1749 /* Disconnect from the controlling tty. */ 1750 #ifdef TIOCNOTTY 1751 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1752 if (fd >= 0) { 1753 (void) ioctl(fd, TIOCNOTTY, NULL); 1754 close(fd); 1755 } 1756 #endif /* TIOCNOTTY */ 1757 } 1758 /* Reinitialize the log (because of the fork above). */ 1759 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1760 1761 /* Avoid killing the process in high-pressure swapping environments. */ 1762 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 1763 debug("madvise(): %.200s", strerror(errno)); 1764 1765 /* Initialize the random number generator. */ 1766 arc4random_stir(); 1767 1768 /* Chdir to the root directory so that the current disk can be 1769 unmounted if desired. */ 1770 chdir("/"); 1771 1772 /* ignore SIGPIPE */ 1773 signal(SIGPIPE, SIG_IGN); 1774 1775 /* Get a connection, either from inetd or a listening TCP socket */ 1776 if (inetd_flag) { 1777 server_accept_inetd(&sock_in, &sock_out); 1778 } else { 1779 platform_pre_listen(); 1780 server_listen(); 1781 1782 if (options.protocol & SSH_PROTO_1) 1783 generate_ephemeral_server_key(); 1784 1785 signal(SIGHUP, sighup_handler); 1786 signal(SIGCHLD, main_sigchld_handler); 1787 signal(SIGTERM, sigterm_handler); 1788 signal(SIGQUIT, sigterm_handler); 1789 1790 /* 1791 * Write out the pid file after the sigterm handler 1792 * is setup and the listen sockets are bound 1793 */ 1794 if (!debug_flag) { 1795 FILE *f = fopen(options.pid_file, "w"); 1796 1797 if (f == NULL) { 1798 error("Couldn't create pid file \"%s\": %s", 1799 options.pid_file, strerror(errno)); 1800 } else { 1801 fprintf(f, "%ld\n", (long) getpid()); 1802 fclose(f); 1803 } 1804 } 1805 1806 /* Accept a connection and return in a forked child */ 1807 server_accept_loop(&sock_in, &sock_out, 1808 &newsock, config_s); 1809 } 1810 1811 /* This is the child processing a new connection. */ 1812 setproctitle("%s", "[accepted]"); 1813 1814 /* 1815 * Create a new session and process group since the 4.4BSD 1816 * setlogin() affects the entire process group. We don't 1817 * want the child to be able to affect the parent. 1818 */ 1819 #if !defined(SSHD_ACQUIRES_CTTY) 1820 /* 1821 * If setsid is called, on some platforms sshd will later acquire a 1822 * controlling terminal which will result in "could not set 1823 * controlling tty" errors. 1824 */ 1825 if (!debug_flag && !inetd_flag && setsid() < 0) 1826 error("setsid: %.100s", strerror(errno)); 1827 #endif 1828 1829 if (rexec_flag) { 1830 int fd; 1831 1832 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1833 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1834 dup2(newsock, STDIN_FILENO); 1835 dup2(STDIN_FILENO, STDOUT_FILENO); 1836 if (startup_pipe == -1) 1837 close(REEXEC_STARTUP_PIPE_FD); 1838 else 1839 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1840 1841 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1842 close(config_s[1]); 1843 if (startup_pipe != -1) 1844 close(startup_pipe); 1845 1846 execv(rexec_argv[0], rexec_argv); 1847 1848 /* Reexec has failed, fall back and continue */ 1849 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1850 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1851 log_init(__progname, options.log_level, 1852 options.log_facility, log_stderr); 1853 1854 /* Clean up fds */ 1855 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1856 close(config_s[1]); 1857 close(REEXEC_CONFIG_PASS_FD); 1858 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1859 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1860 dup2(fd, STDIN_FILENO); 1861 dup2(fd, STDOUT_FILENO); 1862 if (fd > STDERR_FILENO) 1863 close(fd); 1864 } 1865 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1866 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1867 } 1868 1869 /* Executed child processes don't need these. */ 1870 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1871 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1872 1873 /* 1874 * Disable the key regeneration alarm. We will not regenerate the 1875 * key since we are no longer in a position to give it to anyone. We 1876 * will not restart on SIGHUP since it no longer makes sense. 1877 */ 1878 alarm(0); 1879 signal(SIGALRM, SIG_DFL); 1880 signal(SIGHUP, SIG_DFL); 1881 signal(SIGTERM, SIG_DFL); 1882 signal(SIGQUIT, SIG_DFL); 1883 signal(SIGCHLD, SIG_DFL); 1884 signal(SIGINT, SIG_DFL); 1885 1886 #ifdef __FreeBSD__ 1887 /* 1888 * Initialize the resolver. This may not happen automatically 1889 * before privsep chroot(). 1890 */ 1891 if ((_res.options & RES_INIT) == 0) { 1892 debug("res_init()"); 1893 res_init(); 1894 } 1895 #ifdef GSSAPI 1896 /* 1897 * Force GSS-API to parse its configuration and load any 1898 * mechanism plugins. 1899 */ 1900 { 1901 gss_OID_set mechs; 1902 OM_uint32 minor_status; 1903 gss_indicate_mechs(&minor_status, &mechs); 1904 gss_release_oid_set(&minor_status, &mechs); 1905 } 1906 #endif 1907 #endif 1908 1909 /* 1910 * Register our connection. This turns encryption off because we do 1911 * not have a key. 1912 */ 1913 packet_set_connection(sock_in, sock_out); 1914 packet_set_server(); 1915 1916 /* Set SO_KEEPALIVE if requested. */ 1917 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1918 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1919 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1920 1921 if ((remote_port = get_remote_port()) < 0) { 1922 debug("get_remote_port failed"); 1923 cleanup_exit(255); 1924 } 1925 1926 /* 1927 * We use get_canonical_hostname with usedns = 0 instead of 1928 * get_remote_ipaddr here so IP options will be checked. 1929 */ 1930 (void) get_canonical_hostname(0); 1931 /* 1932 * The rest of the code depends on the fact that 1933 * get_remote_ipaddr() caches the remote ip, even if 1934 * the socket goes away. 1935 */ 1936 remote_ip = get_remote_ipaddr(); 1937 1938 #ifdef SSH_AUDIT_EVENTS 1939 audit_connection_from(remote_ip, remote_port); 1940 #endif 1941 #ifdef LIBWRAP 1942 allow_severity = options.log_facility|LOG_INFO; 1943 deny_severity = options.log_facility|LOG_WARNING; 1944 /* Check whether logins are denied from this host. */ 1945 if (packet_connection_is_on_socket()) { 1946 struct request_info req; 1947 1948 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 1949 fromhost(&req); 1950 1951 if (!hosts_access(&req)) { 1952 debug("Connection refused by tcp wrapper"); 1953 refuse(&req); 1954 /* NOTREACHED */ 1955 fatal("libwrap refuse returns"); 1956 } 1957 } 1958 #endif /* LIBWRAP */ 1959 1960 /* Log the connection. */ 1961 verbose("Connection from %.500s port %d", remote_ip, remote_port); 1962 1963 /* 1964 * We don't want to listen forever unless the other side 1965 * successfully authenticates itself. So we set up an alarm which is 1966 * cleared after successful authentication. A limit of zero 1967 * indicates no limit. Note that we don't set the alarm in debugging 1968 * mode; it is just annoying to have the server exit just when you 1969 * are about to discover the bug. 1970 */ 1971 signal(SIGALRM, grace_alarm_handler); 1972 if (!debug_flag) 1973 alarm(options.login_grace_time); 1974 1975 sshd_exchange_identification(sock_in, sock_out); 1976 1977 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 1978 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 1979 generate_ephemeral_server_key(); 1980 1981 packet_set_nonblocking(); 1982 1983 /* allocate authentication context */ 1984 authctxt = xcalloc(1, sizeof(*authctxt)); 1985 1986 authctxt->loginmsg = &loginmsg; 1987 1988 /* XXX global for cleanup, access from other modules */ 1989 the_authctxt = authctxt; 1990 1991 /* prepare buffer to collect messages to display to user after login */ 1992 buffer_init(&loginmsg); 1993 auth_debug_reset(); 1994 1995 if (use_privsep) 1996 if (privsep_preauth(authctxt) == 1) 1997 goto authenticated; 1998 1999 /* perform the key exchange */ 2000 /* authenticate user and start session */ 2001 if (compat20) { 2002 do_ssh2_kex(); 2003 do_authentication2(authctxt); 2004 } else { 2005 do_ssh1_kex(); 2006 do_authentication(authctxt); 2007 } 2008 /* 2009 * If we use privilege separation, the unprivileged child transfers 2010 * the current keystate and exits 2011 */ 2012 if (use_privsep) { 2013 mm_send_keystate(pmonitor); 2014 exit(0); 2015 } 2016 2017 authenticated: 2018 /* 2019 * Cancel the alarm we set to limit the time taken for 2020 * authentication. 2021 */ 2022 alarm(0); 2023 signal(SIGALRM, SIG_DFL); 2024 authctxt->authenticated = 1; 2025 if (startup_pipe != -1) { 2026 close(startup_pipe); 2027 startup_pipe = -1; 2028 } 2029 2030 #ifdef SSH_AUDIT_EVENTS 2031 audit_event(SSH_AUTH_SUCCESS); 2032 #endif 2033 2034 #ifdef GSSAPI 2035 if (options.gss_authentication) { 2036 temporarily_use_uid(authctxt->pw); 2037 ssh_gssapi_storecreds(); 2038 restore_uid(); 2039 } 2040 #endif 2041 #ifdef USE_PAM 2042 if (options.use_pam) { 2043 do_pam_setcred(1); 2044 do_pam_session(); 2045 } 2046 #endif 2047 2048 /* 2049 * In privilege separation, we fork another child and prepare 2050 * file descriptor passing. 2051 */ 2052 if (use_privsep) { 2053 privsep_postauth(authctxt); 2054 /* the monitor process [priv] will not return */ 2055 if (!compat20) 2056 destroy_sensitive_data(); 2057 } 2058 2059 packet_set_timeout(options.client_alive_interval, 2060 options.client_alive_count_max); 2061 2062 /* Start session. */ 2063 do_authenticated(authctxt); 2064 2065 /* The connection has been terminated. */ 2066 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 2067 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 2068 verbose("Transferred: sent %llu, received %llu bytes", 2069 (unsigned long long)obytes, (unsigned long long)ibytes); 2070 2071 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2072 2073 #ifdef USE_PAM 2074 if (options.use_pam) 2075 finish_pam(); 2076 #endif /* USE_PAM */ 2077 2078 #ifdef SSH_AUDIT_EVENTS 2079 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2080 #endif 2081 2082 packet_close(); 2083 2084 if (use_privsep) 2085 mm_terminate(); 2086 2087 exit(0); 2088 } 2089 2090 /* 2091 * Decrypt session_key_int using our private server key and private host key 2092 * (key with larger modulus first). 2093 */ 2094 int 2095 ssh1_session_key(BIGNUM *session_key_int) 2096 { 2097 int rsafail = 0; 2098 2099 if (BN_cmp(sensitive_data.server_key->rsa->n, 2100 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2101 /* Server key has bigger modulus. */ 2102 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2103 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2104 SSH_KEY_BITS_RESERVED) { 2105 fatal("do_connection: %s: " 2106 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2107 get_remote_ipaddr(), 2108 BN_num_bits(sensitive_data.server_key->rsa->n), 2109 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2110 SSH_KEY_BITS_RESERVED); 2111 } 2112 if (rsa_private_decrypt(session_key_int, session_key_int, 2113 sensitive_data.server_key->rsa) <= 0) 2114 rsafail++; 2115 if (rsa_private_decrypt(session_key_int, session_key_int, 2116 sensitive_data.ssh1_host_key->rsa) <= 0) 2117 rsafail++; 2118 } else { 2119 /* Host key has bigger modulus (or they are equal). */ 2120 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2121 BN_num_bits(sensitive_data.server_key->rsa->n) + 2122 SSH_KEY_BITS_RESERVED) { 2123 fatal("do_connection: %s: " 2124 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2125 get_remote_ipaddr(), 2126 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2127 BN_num_bits(sensitive_data.server_key->rsa->n), 2128 SSH_KEY_BITS_RESERVED); 2129 } 2130 if (rsa_private_decrypt(session_key_int, session_key_int, 2131 sensitive_data.ssh1_host_key->rsa) < 0) 2132 rsafail++; 2133 if (rsa_private_decrypt(session_key_int, session_key_int, 2134 sensitive_data.server_key->rsa) < 0) 2135 rsafail++; 2136 } 2137 return (rsafail); 2138 } 2139 /* 2140 * SSH1 key exchange 2141 */ 2142 static void 2143 do_ssh1_kex(void) 2144 { 2145 int i, len; 2146 int rsafail = 0; 2147 BIGNUM *session_key_int; 2148 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2149 u_char cookie[8]; 2150 u_int cipher_type, auth_mask, protocol_flags; 2151 2152 /* 2153 * Generate check bytes that the client must send back in the user 2154 * packet in order for it to be accepted; this is used to defy ip 2155 * spoofing attacks. Note that this only works against somebody 2156 * doing IP spoofing from a remote machine; any machine on the local 2157 * network can still see outgoing packets and catch the random 2158 * cookie. This only affects rhosts authentication, and this is one 2159 * of the reasons why it is inherently insecure. 2160 */ 2161 arc4random_buf(cookie, sizeof(cookie)); 2162 2163 /* 2164 * Send our public key. We include in the packet 64 bits of random 2165 * data that must be matched in the reply in order to prevent IP 2166 * spoofing. 2167 */ 2168 packet_start(SSH_SMSG_PUBLIC_KEY); 2169 for (i = 0; i < 8; i++) 2170 packet_put_char(cookie[i]); 2171 2172 /* Store our public server RSA key. */ 2173 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2174 packet_put_bignum(sensitive_data.server_key->rsa->e); 2175 packet_put_bignum(sensitive_data.server_key->rsa->n); 2176 2177 /* Store our public host RSA key. */ 2178 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2179 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2180 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2181 2182 /* Put protocol flags. */ 2183 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2184 2185 /* Declare which ciphers we support. */ 2186 packet_put_int(cipher_mask_ssh1(0)); 2187 2188 /* Declare supported authentication types. */ 2189 auth_mask = 0; 2190 if (options.rhosts_rsa_authentication) 2191 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2192 if (options.rsa_authentication) 2193 auth_mask |= 1 << SSH_AUTH_RSA; 2194 if (options.challenge_response_authentication == 1) 2195 auth_mask |= 1 << SSH_AUTH_TIS; 2196 if (options.password_authentication) 2197 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2198 packet_put_int(auth_mask); 2199 2200 /* Send the packet and wait for it to be sent. */ 2201 packet_send(); 2202 packet_write_wait(); 2203 2204 debug("Sent %d bit server key and %d bit host key.", 2205 BN_num_bits(sensitive_data.server_key->rsa->n), 2206 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2207 2208 /* Read clients reply (cipher type and session key). */ 2209 packet_read_expect(SSH_CMSG_SESSION_KEY); 2210 2211 /* Get cipher type and check whether we accept this. */ 2212 cipher_type = packet_get_char(); 2213 2214 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2215 packet_disconnect("Warning: client selects unsupported cipher."); 2216 2217 /* Get check bytes from the packet. These must match those we 2218 sent earlier with the public key packet. */ 2219 for (i = 0; i < 8; i++) 2220 if (cookie[i] != packet_get_char()) 2221 packet_disconnect("IP Spoofing check bytes do not match."); 2222 2223 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2224 2225 /* Get the encrypted integer. */ 2226 if ((session_key_int = BN_new()) == NULL) 2227 fatal("do_ssh1_kex: BN_new failed"); 2228 packet_get_bignum(session_key_int); 2229 2230 protocol_flags = packet_get_int(); 2231 packet_set_protocol_flags(protocol_flags); 2232 packet_check_eom(); 2233 2234 /* Decrypt session_key_int using host/server keys */ 2235 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2236 2237 /* 2238 * Extract session key from the decrypted integer. The key is in the 2239 * least significant 256 bits of the integer; the first byte of the 2240 * key is in the highest bits. 2241 */ 2242 if (!rsafail) { 2243 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2244 len = BN_num_bytes(session_key_int); 2245 if (len < 0 || (u_int)len > sizeof(session_key)) { 2246 error("do_ssh1_kex: bad session key len from %s: " 2247 "session_key_int %d > sizeof(session_key) %lu", 2248 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2249 rsafail++; 2250 } else { 2251 memset(session_key, 0, sizeof(session_key)); 2252 BN_bn2bin(session_key_int, 2253 session_key + sizeof(session_key) - len); 2254 2255 derive_ssh1_session_id( 2256 sensitive_data.ssh1_host_key->rsa->n, 2257 sensitive_data.server_key->rsa->n, 2258 cookie, session_id); 2259 /* 2260 * Xor the first 16 bytes of the session key with the 2261 * session id. 2262 */ 2263 for (i = 0; i < 16; i++) 2264 session_key[i] ^= session_id[i]; 2265 } 2266 } 2267 if (rsafail) { 2268 int bytes = BN_num_bytes(session_key_int); 2269 u_char *buf = xmalloc(bytes); 2270 MD5_CTX md; 2271 2272 logit("do_connection: generating a fake encryption key"); 2273 BN_bn2bin(session_key_int, buf); 2274 MD5_Init(&md); 2275 MD5_Update(&md, buf, bytes); 2276 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2277 MD5_Final(session_key, &md); 2278 MD5_Init(&md); 2279 MD5_Update(&md, session_key, 16); 2280 MD5_Update(&md, buf, bytes); 2281 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2282 MD5_Final(session_key + 16, &md); 2283 memset(buf, 0, bytes); 2284 xfree(buf); 2285 for (i = 0; i < 16; i++) 2286 session_id[i] = session_key[i] ^ session_key[i + 16]; 2287 } 2288 /* Destroy the private and public keys. No longer. */ 2289 destroy_sensitive_data(); 2290 2291 if (use_privsep) 2292 mm_ssh1_session_id(session_id); 2293 2294 /* Destroy the decrypted integer. It is no longer needed. */ 2295 BN_clear_free(session_key_int); 2296 2297 /* Set the session key. From this on all communications will be encrypted. */ 2298 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2299 2300 /* Destroy our copy of the session key. It is no longer needed. */ 2301 memset(session_key, 0, sizeof(session_key)); 2302 2303 debug("Received session key; encryption turned on."); 2304 2305 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2306 packet_start(SSH_SMSG_SUCCESS); 2307 packet_send(); 2308 packet_write_wait(); 2309 } 2310 2311 /* 2312 * SSH2 key exchange: diffie-hellman-group1-sha1 2313 */ 2314 static void 2315 do_ssh2_kex(void) 2316 { 2317 Kex *kex; 2318 2319 if (options.ciphers != NULL) { 2320 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2321 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2322 } 2323 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2324 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2325 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2326 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2327 2328 if (options.macs != NULL) { 2329 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2330 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2331 } 2332 if (options.compression == COMP_NONE) { 2333 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2334 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2335 } else if (options.compression == COMP_DELAYED) { 2336 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2337 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2338 } 2339 if (options.kex_algorithms != NULL) 2340 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 2341 2342 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); 2343 2344 /* start key exchange */ 2345 kex = kex_setup(myproposal); 2346 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2347 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2348 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2349 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2350 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2351 kex->server = 1; 2352 kex->client_version_string=client_version_string; 2353 kex->server_version_string=server_version_string; 2354 kex->load_host_public_key=&get_hostkey_public_by_type; 2355 kex->load_host_private_key=&get_hostkey_private_by_type; 2356 kex->host_key_index=&get_hostkey_index; 2357 2358 xxx_kex = kex; 2359 2360 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2361 2362 session_id2 = kex->session_id; 2363 session_id2_len = kex->session_id_len; 2364 2365 #ifdef DEBUG_KEXDH 2366 /* send 1st encrypted/maced/compressed message */ 2367 packet_start(SSH2_MSG_IGNORE); 2368 packet_put_cstring("markus"); 2369 packet_send(); 2370 packet_write_wait(); 2371 #endif 2372 debug("KEX done"); 2373 } 2374 2375 /* server specific fatal cleanup */ 2376 void 2377 cleanup_exit(int i) 2378 { 2379 if (the_authctxt) 2380 do_cleanup(the_authctxt); 2381 #ifdef SSH_AUDIT_EVENTS 2382 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2383 if (!use_privsep || mm_is_monitor()) 2384 audit_event(SSH_CONNECTION_ABANDON); 2385 #endif 2386 _exit(i); 2387 } 2388