1 /* $OpenBSD: sshd.c,v 1.366 2009/01/22 10:02:34 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/socket.h> 51 #ifdef HAVE_SYS_STAT_H 52 # include <sys/stat.h> 53 #endif 54 #ifdef HAVE_SYS_TIME_H 55 # include <sys/time.h> 56 #endif 57 #include "openbsd-compat/sys-tree.h" 58 #include "openbsd-compat/sys-queue.h" 59 #include <sys/wait.h> 60 61 #include <errno.h> 62 #include <fcntl.h> 63 #include <netdb.h> 64 #ifdef HAVE_PATHS_H 65 #include <paths.h> 66 #endif 67 #include <grp.h> 68 #include <pwd.h> 69 #include <signal.h> 70 #include <stdarg.h> 71 #include <stdio.h> 72 #include <stdlib.h> 73 #include <string.h> 74 #include <unistd.h> 75 #include <utmp.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 "version.h" 132 133 #ifdef LIBWRAP 134 #include <tcpd.h> 135 #include <syslog.h> 136 int allow_severity; 137 int deny_severity; 138 #endif /* LIBWRAP */ 139 140 #ifndef O_NOCTTY 141 #define O_NOCTTY 0 142 #endif 143 144 /* Re-exec fds */ 145 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 146 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 147 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 148 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 149 150 extern char *__progname; 151 152 /* Server configuration options. */ 153 ServerOptions options; 154 155 /* Name of the server configuration file. */ 156 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 157 158 /* 159 * Debug mode flag. This can be set on the command line. If debug 160 * mode is enabled, extra debugging output will be sent to the system 161 * log, the daemon will not go to background, and will exit after processing 162 * the first connection. 163 */ 164 int debug_flag = 0; 165 166 /* Flag indicating that the daemon should only test the configuration and keys. */ 167 int test_flag = 0; 168 169 /* Flag indicating that the daemon is being started from inetd. */ 170 int inetd_flag = 0; 171 172 /* Flag indicating that sshd should not detach and become a daemon. */ 173 int no_daemon_flag = 0; 174 175 /* debug goes to stderr unless inetd_flag is set */ 176 int log_stderr = 0; 177 178 /* Saved arguments to main(). */ 179 char **saved_argv; 180 int saved_argc; 181 182 /* re-exec */ 183 int rexeced_flag = 0; 184 int rexec_flag = 1; 185 int rexec_argc = 0; 186 char **rexec_argv; 187 188 /* 189 * The sockets that the server is listening; this is used in the SIGHUP 190 * signal handler. 191 */ 192 #define MAX_LISTEN_SOCKS 16 193 int listen_socks[MAX_LISTEN_SOCKS]; 194 int num_listen_socks = 0; 195 196 /* 197 * the client's version string, passed by sshd2 in compat mode. if != NULL, 198 * sshd will skip the version-number exchange 199 */ 200 char *client_version_string = NULL; 201 char *server_version_string = NULL; 202 203 /* for rekeying XXX fixme */ 204 Kex *xxx_kex; 205 206 /* 207 * Any really sensitive data in the application is contained in this 208 * structure. The idea is that this structure could be locked into memory so 209 * that the pages do not get written into swap. However, there are some 210 * problems. The private key contains BIGNUMs, and we do not (in principle) 211 * have access to the internals of them, and locking just the structure is 212 * not very useful. Currently, memory locking is not implemented. 213 */ 214 struct { 215 Key *server_key; /* ephemeral server key */ 216 Key *ssh1_host_key; /* ssh1 host key */ 217 Key **host_keys; /* all private host keys */ 218 int have_ssh1_key; 219 int have_ssh2_key; 220 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 221 } sensitive_data; 222 223 /* 224 * Flag indicating whether the RSA server key needs to be regenerated. 225 * Is set in the SIGALRM handler and cleared when the key is regenerated. 226 */ 227 static volatile sig_atomic_t key_do_regen = 0; 228 229 /* This is set to true when a signal is received. */ 230 static volatile sig_atomic_t received_sighup = 0; 231 static volatile sig_atomic_t received_sigterm = 0; 232 233 /* session identifier, used by RSA-auth */ 234 u_char session_id[16]; 235 236 /* same for ssh2 */ 237 u_char *session_id2 = NULL; 238 u_int session_id2_len = 0; 239 240 /* record remote hostname or ip */ 241 u_int utmp_len = UT_HOSTSIZE; 242 243 /* options.max_startup sized array of fd ints */ 244 int *startup_pipes = NULL; 245 int startup_pipe; /* in child */ 246 247 /* variables used for privilege separation */ 248 int use_privsep = -1; 249 struct monitor *pmonitor = NULL; 250 251 /* global authentication context */ 252 Authctxt *the_authctxt = NULL; 253 254 /* sshd_config buffer */ 255 Buffer cfg; 256 257 /* message to be displayed after login */ 258 Buffer loginmsg; 259 260 /* Unprivileged user */ 261 struct passwd *privsep_pw = NULL; 262 263 /* Prototypes for various functions defined later in this file. */ 264 void destroy_sensitive_data(void); 265 void demote_sensitive_data(void); 266 267 static void do_ssh1_kex(void); 268 static void do_ssh2_kex(void); 269 270 /* 271 * Close all listening sockets 272 */ 273 static void 274 close_listen_socks(void) 275 { 276 int i; 277 278 for (i = 0; i < num_listen_socks; i++) 279 close(listen_socks[i]); 280 num_listen_socks = -1; 281 } 282 283 static void 284 close_startup_pipes(void) 285 { 286 int i; 287 288 if (startup_pipes) 289 for (i = 0; i < options.max_startups; i++) 290 if (startup_pipes[i] != -1) 291 close(startup_pipes[i]); 292 } 293 294 /* 295 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 296 * the effect is to reread the configuration file (and to regenerate 297 * the server key). 298 */ 299 300 /*ARGSUSED*/ 301 static void 302 sighup_handler(int sig) 303 { 304 int save_errno = errno; 305 306 received_sighup = 1; 307 signal(SIGHUP, sighup_handler); 308 errno = save_errno; 309 } 310 311 /* 312 * Called from the main program after receiving SIGHUP. 313 * Restarts the server. 314 */ 315 static void 316 sighup_restart(void) 317 { 318 logit("Received SIGHUP; restarting."); 319 close_listen_socks(); 320 close_startup_pipes(); 321 alarm(0); /* alarm timer persists across exec */ 322 execv(saved_argv[0], saved_argv); 323 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 324 strerror(errno)); 325 exit(1); 326 } 327 328 /* 329 * Generic signal handler for terminating signals in the master daemon. 330 */ 331 /*ARGSUSED*/ 332 static void 333 sigterm_handler(int sig) 334 { 335 received_sigterm = sig; 336 } 337 338 /* 339 * SIGCHLD handler. This is called whenever a child dies. This will then 340 * reap any zombies left by exited children. 341 */ 342 /*ARGSUSED*/ 343 static void 344 main_sigchld_handler(int sig) 345 { 346 int save_errno = errno; 347 pid_t pid; 348 int status; 349 350 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 351 (pid < 0 && errno == EINTR)) 352 ; 353 354 signal(SIGCHLD, main_sigchld_handler); 355 errno = save_errno; 356 } 357 358 /* 359 * Signal handler for the alarm after the login grace period has expired. 360 */ 361 /*ARGSUSED*/ 362 static void 363 grace_alarm_handler(int sig) 364 { 365 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 366 kill(pmonitor->m_pid, SIGALRM); 367 368 /* Log error and exit. */ 369 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 370 } 371 372 /* 373 * Signal handler for the key regeneration alarm. Note that this 374 * alarm only occurs in the daemon waiting for connections, and it does not 375 * do anything with the private key or random state before forking. 376 * Thus there should be no concurrency control/asynchronous execution 377 * problems. 378 */ 379 static void 380 generate_ephemeral_server_key(void) 381 { 382 verbose("Generating %s%d bit RSA key.", 383 sensitive_data.server_key ? "new " : "", options.server_key_bits); 384 if (sensitive_data.server_key != NULL) 385 key_free(sensitive_data.server_key); 386 sensitive_data.server_key = key_generate(KEY_RSA1, 387 options.server_key_bits); 388 verbose("RSA key generation complete."); 389 390 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 391 arc4random_stir(); 392 } 393 394 /*ARGSUSED*/ 395 static void 396 key_regeneration_alarm(int sig) 397 { 398 int save_errno = errno; 399 400 signal(SIGALRM, SIG_DFL); 401 errno = save_errno; 402 key_do_regen = 1; 403 } 404 405 static void 406 sshd_exchange_identification(int sock_in, int sock_out) 407 { 408 u_int i; 409 int mismatch; 410 int remote_major, remote_minor; 411 int major, minor; 412 char *s, *newline = "\n"; 413 char buf[256]; /* Must not be larger than remote_version. */ 414 char remote_version[256]; /* Must be at least as big as buf. */ 415 416 if ((options.protocol & SSH_PROTO_1) && 417 (options.protocol & SSH_PROTO_2)) { 418 major = PROTOCOL_MAJOR_1; 419 minor = 99; 420 } else if (options.protocol & SSH_PROTO_2) { 421 major = PROTOCOL_MAJOR_2; 422 minor = PROTOCOL_MINOR_2; 423 newline = "\r\n"; 424 } else { 425 major = PROTOCOL_MAJOR_1; 426 minor = PROTOCOL_MINOR_1; 427 } 428 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor, 429 SSH_VERSION, newline); 430 server_version_string = xstrdup(buf); 431 432 /* Send our protocol version identification. */ 433 if (atomicio(vwrite, sock_out, server_version_string, 434 strlen(server_version_string)) 435 != strlen(server_version_string)) { 436 logit("Could not write ident string to %s", get_remote_ipaddr()); 437 cleanup_exit(255); 438 } 439 440 /* Read other sides version identification. */ 441 memset(buf, 0, sizeof(buf)); 442 for (i = 0; i < sizeof(buf) - 1; i++) { 443 if (atomicio(read, sock_in, &buf[i], 1) != 1) { 444 logit("Did not receive identification string from %s", 445 get_remote_ipaddr()); 446 cleanup_exit(255); 447 } 448 if (buf[i] == '\r') { 449 buf[i] = 0; 450 /* Kludge for F-Secure Macintosh < 1.0.2 */ 451 if (i == 12 && 452 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 453 break; 454 continue; 455 } 456 if (buf[i] == '\n') { 457 buf[i] = 0; 458 break; 459 } 460 } 461 buf[sizeof(buf) - 1] = 0; 462 client_version_string = xstrdup(buf); 463 464 /* 465 * Check that the versions match. In future this might accept 466 * several versions and set appropriate flags to handle them. 467 */ 468 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 469 &remote_major, &remote_minor, remote_version) != 3) { 470 s = "Protocol mismatch.\n"; 471 (void) atomicio(vwrite, sock_out, s, strlen(s)); 472 close(sock_in); 473 close(sock_out); 474 logit("Bad protocol version identification '%.100s' from %s", 475 client_version_string, get_remote_ipaddr()); 476 cleanup_exit(255); 477 } 478 debug("Client protocol version %d.%d; client software version %.100s", 479 remote_major, remote_minor, remote_version); 480 481 compat_datafellows(remote_version); 482 483 if (datafellows & SSH_BUG_PROBE) { 484 logit("probed from %s with %s. Don't panic.", 485 get_remote_ipaddr(), client_version_string); 486 cleanup_exit(255); 487 } 488 489 if (datafellows & SSH_BUG_SCANNER) { 490 logit("scanned from %s with %s. Don't panic.", 491 get_remote_ipaddr(), client_version_string); 492 cleanup_exit(255); 493 } 494 495 mismatch = 0; 496 switch (remote_major) { 497 case 1: 498 if (remote_minor == 99) { 499 if (options.protocol & SSH_PROTO_2) 500 enable_compat20(); 501 else 502 mismatch = 1; 503 break; 504 } 505 if (!(options.protocol & SSH_PROTO_1)) { 506 mismatch = 1; 507 break; 508 } 509 if (remote_minor < 3) { 510 packet_disconnect("Your ssh version is too old and " 511 "is no longer supported. Please install a newer version."); 512 } else if (remote_minor == 3) { 513 /* note that this disables agent-forwarding */ 514 enable_compat13(); 515 } 516 break; 517 case 2: 518 if (options.protocol & SSH_PROTO_2) { 519 enable_compat20(); 520 break; 521 } 522 /* FALLTHROUGH */ 523 default: 524 mismatch = 1; 525 break; 526 } 527 chop(server_version_string); 528 debug("Local version string %.200s", server_version_string); 529 530 if (mismatch) { 531 s = "Protocol major versions differ.\n"; 532 (void) atomicio(vwrite, sock_out, s, strlen(s)); 533 close(sock_in); 534 close(sock_out); 535 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 536 get_remote_ipaddr(), 537 server_version_string, client_version_string); 538 cleanup_exit(255); 539 } 540 } 541 542 /* Destroy the host and server keys. They will no longer be needed. */ 543 void 544 destroy_sensitive_data(void) 545 { 546 int i; 547 548 if (sensitive_data.server_key) { 549 key_free(sensitive_data.server_key); 550 sensitive_data.server_key = NULL; 551 } 552 for (i = 0; i < options.num_host_key_files; i++) { 553 if (sensitive_data.host_keys[i]) { 554 key_free(sensitive_data.host_keys[i]); 555 sensitive_data.host_keys[i] = NULL; 556 } 557 } 558 sensitive_data.ssh1_host_key = NULL; 559 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); 560 } 561 562 /* Demote private to public keys for network child */ 563 void 564 demote_sensitive_data(void) 565 { 566 Key *tmp; 567 int i; 568 569 if (sensitive_data.server_key) { 570 tmp = key_demote(sensitive_data.server_key); 571 key_free(sensitive_data.server_key); 572 sensitive_data.server_key = tmp; 573 } 574 575 for (i = 0; i < options.num_host_key_files; i++) { 576 if (sensitive_data.host_keys[i]) { 577 tmp = key_demote(sensitive_data.host_keys[i]); 578 key_free(sensitive_data.host_keys[i]); 579 sensitive_data.host_keys[i] = tmp; 580 if (tmp->type == KEY_RSA1) 581 sensitive_data.ssh1_host_key = tmp; 582 } 583 } 584 585 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 586 } 587 588 static void 589 privsep_preauth_child(void) 590 { 591 u_int32_t rnd[256]; 592 gid_t gidset[1]; 593 594 /* Enable challenge-response authentication for privilege separation */ 595 privsep_challenge_enable(); 596 597 arc4random_stir(); 598 arc4random_buf(rnd, sizeof(rnd)); 599 RAND_seed(rnd, sizeof(rnd)); 600 601 /* Demote the private keys to public keys. */ 602 demote_sensitive_data(); 603 604 /* Change our root directory */ 605 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 606 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 607 strerror(errno)); 608 if (chdir("/") == -1) 609 fatal("chdir(\"/\"): %s", strerror(errno)); 610 611 /* Drop our privileges */ 612 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 613 (u_int)privsep_pw->pw_gid); 614 #if 0 615 /* XXX not ready, too heavy after chroot */ 616 do_setusercontext(privsep_pw); 617 #else 618 gidset[0] = privsep_pw->pw_gid; 619 if (setgroups(1, gidset) < 0) 620 fatal("setgroups: %.100s", strerror(errno)); 621 permanently_set_uid(privsep_pw); 622 #endif 623 } 624 625 static int 626 privsep_preauth(Authctxt *authctxt) 627 { 628 int status; 629 pid_t pid; 630 631 /* Set up unprivileged child process to deal with network data */ 632 pmonitor = monitor_init(); 633 /* Store a pointer to the kex for later rekeying */ 634 pmonitor->m_pkex = &xxx_kex; 635 636 pid = fork(); 637 if (pid == -1) { 638 fatal("fork of unprivileged child failed"); 639 } else if (pid != 0) { 640 debug2("Network child is on pid %ld", (long)pid); 641 642 close(pmonitor->m_recvfd); 643 pmonitor->m_pid = pid; 644 monitor_child_preauth(authctxt, pmonitor); 645 close(pmonitor->m_sendfd); 646 647 /* Sync memory */ 648 monitor_sync(pmonitor); 649 650 /* Wait for the child's exit status */ 651 while (waitpid(pid, &status, 0) < 0) 652 if (errno != EINTR) 653 break; 654 return (1); 655 } else { 656 /* child */ 657 658 close(pmonitor->m_sendfd); 659 660 /* Demote the child */ 661 if (getuid() == 0 || geteuid() == 0) 662 privsep_preauth_child(); 663 setproctitle("%s", "[net]"); 664 } 665 return (0); 666 } 667 668 static void 669 privsep_postauth(Authctxt *authctxt) 670 { 671 u_int32_t rnd[256]; 672 673 #ifdef DISABLE_FD_PASSING 674 if (1) { 675 #else 676 if (authctxt->pw->pw_uid == 0 || options.use_login) { 677 #endif 678 /* File descriptor passing is broken or root login */ 679 use_privsep = 0; 680 goto skip; 681 } 682 683 /* New socket pair */ 684 monitor_reinit(pmonitor); 685 686 pmonitor->m_pid = fork(); 687 if (pmonitor->m_pid == -1) 688 fatal("fork of unprivileged child failed"); 689 else if (pmonitor->m_pid != 0) { 690 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 691 close(pmonitor->m_recvfd); 692 buffer_clear(&loginmsg); 693 monitor_child_postauth(pmonitor); 694 695 /* NEVERREACHED */ 696 exit(0); 697 } 698 699 close(pmonitor->m_sendfd); 700 701 /* Demote the private keys to public keys. */ 702 demote_sensitive_data(); 703 704 arc4random_stir(); 705 arc4random_buf(rnd, sizeof(rnd)); 706 RAND_seed(rnd, sizeof(rnd)); 707 708 /* Drop privileges */ 709 do_setusercontext(authctxt->pw); 710 711 skip: 712 /* It is safe now to apply the key state */ 713 monitor_apply_keystate(pmonitor); 714 715 /* 716 * Tell the packet layer that authentication was successful, since 717 * this information is not part of the key state. 718 */ 719 packet_set_authenticated(); 720 } 721 722 static char * 723 list_hostkey_types(void) 724 { 725 Buffer b; 726 const char *p; 727 char *ret; 728 int i; 729 730 buffer_init(&b); 731 for (i = 0; i < options.num_host_key_files; i++) { 732 Key *key = sensitive_data.host_keys[i]; 733 if (key == NULL) 734 continue; 735 switch (key->type) { 736 case KEY_RSA: 737 case KEY_DSA: 738 if (buffer_len(&b) > 0) 739 buffer_append(&b, ",", 1); 740 p = key_ssh_name(key); 741 buffer_append(&b, p, strlen(p)); 742 break; 743 } 744 } 745 buffer_append(&b, "\0", 1); 746 ret = xstrdup(buffer_ptr(&b)); 747 buffer_free(&b); 748 debug("list_hostkey_types: %s", ret); 749 return ret; 750 } 751 752 Key * 753 get_hostkey_by_type(int type) 754 { 755 int i; 756 757 for (i = 0; i < options.num_host_key_files; i++) { 758 Key *key = sensitive_data.host_keys[i]; 759 if (key != NULL && key->type == type) 760 return key; 761 } 762 return NULL; 763 } 764 765 Key * 766 get_hostkey_by_index(int ind) 767 { 768 if (ind < 0 || ind >= options.num_host_key_files) 769 return (NULL); 770 return (sensitive_data.host_keys[ind]); 771 } 772 773 int 774 get_hostkey_index(Key *key) 775 { 776 int i; 777 778 for (i = 0; i < options.num_host_key_files; i++) { 779 if (key == sensitive_data.host_keys[i]) 780 return (i); 781 } 782 return (-1); 783 } 784 785 /* 786 * returns 1 if connection should be dropped, 0 otherwise. 787 * dropping starts at connection #max_startups_begin with a probability 788 * of (max_startups_rate/100). the probability increases linearly until 789 * all connections are dropped for startups > max_startups 790 */ 791 static int 792 drop_connection(int startups) 793 { 794 int p, r; 795 796 if (startups < options.max_startups_begin) 797 return 0; 798 if (startups >= options.max_startups) 799 return 1; 800 if (options.max_startups_rate == 100) 801 return 1; 802 803 p = 100 - options.max_startups_rate; 804 p *= startups - options.max_startups_begin; 805 p /= options.max_startups - options.max_startups_begin; 806 p += options.max_startups_rate; 807 r = arc4random_uniform(100); 808 809 debug("drop_connection: p %d, r %d", p, r); 810 return (r < p) ? 1 : 0; 811 } 812 813 static void 814 usage(void) 815 { 816 fprintf(stderr, "%s, %s\n", 817 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); 818 fprintf(stderr, 819 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-f config_file]\n" 820 " [-g login_grace_time] [-h host_key_file] [-k key_gen_time]\n" 821 " [-o option] [-p port] [-u len]\n" 822 ); 823 exit(1); 824 } 825 826 static void 827 send_rexec_state(int fd, Buffer *conf) 828 { 829 Buffer m; 830 831 debug3("%s: entering fd = %d config len %d", __func__, fd, 832 buffer_len(conf)); 833 834 /* 835 * Protocol from reexec master to child: 836 * string configuration 837 * u_int ephemeral_key_follows 838 * bignum e (only if ephemeral_key_follows == 1) 839 * bignum n " 840 * bignum d " 841 * bignum iqmp " 842 * bignum p " 843 * bignum q " 844 * string rngseed (only if OpenSSL is not self-seeded) 845 */ 846 buffer_init(&m); 847 buffer_put_cstring(&m, buffer_ptr(conf)); 848 849 if (sensitive_data.server_key != NULL && 850 sensitive_data.server_key->type == KEY_RSA1) { 851 buffer_put_int(&m, 1); 852 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 853 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 854 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 855 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 856 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 857 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 858 } else 859 buffer_put_int(&m, 0); 860 861 #ifndef OPENSSL_PRNG_ONLY 862 rexec_send_rng_seed(&m); 863 #endif 864 865 if (ssh_msg_send(fd, 0, &m) == -1) 866 fatal("%s: ssh_msg_send failed", __func__); 867 868 buffer_free(&m); 869 870 debug3("%s: done", __func__); 871 } 872 873 static void 874 recv_rexec_state(int fd, Buffer *conf) 875 { 876 Buffer m; 877 char *cp; 878 u_int len; 879 880 debug3("%s: entering fd = %d", __func__, fd); 881 882 buffer_init(&m); 883 884 if (ssh_msg_recv(fd, &m) == -1) 885 fatal("%s: ssh_msg_recv failed", __func__); 886 if (buffer_get_char(&m) != 0) 887 fatal("%s: rexec version mismatch", __func__); 888 889 cp = buffer_get_string(&m, &len); 890 if (conf != NULL) 891 buffer_append(conf, cp, len + 1); 892 xfree(cp); 893 894 if (buffer_get_int(&m)) { 895 if (sensitive_data.server_key != NULL) 896 key_free(sensitive_data.server_key); 897 sensitive_data.server_key = key_new_private(KEY_RSA1); 898 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 899 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 900 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 901 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 902 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 903 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 904 rsa_generate_additional_parameters( 905 sensitive_data.server_key->rsa); 906 } 907 908 #ifndef OPENSSL_PRNG_ONLY 909 rexec_recv_rng_seed(&m); 910 #endif 911 912 buffer_free(&m); 913 914 debug3("%s: done", __func__); 915 } 916 917 /* Accept a connection from inetd */ 918 static void 919 server_accept_inetd(int *sock_in, int *sock_out) 920 { 921 int fd; 922 923 startup_pipe = -1; 924 if (rexeced_flag) { 925 close(REEXEC_CONFIG_PASS_FD); 926 *sock_in = *sock_out = dup(STDIN_FILENO); 927 if (!debug_flag) { 928 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 929 close(REEXEC_STARTUP_PIPE_FD); 930 } 931 } else { 932 *sock_in = dup(STDIN_FILENO); 933 *sock_out = dup(STDOUT_FILENO); 934 } 935 /* 936 * We intentionally do not close the descriptors 0, 1, and 2 937 * as our code for setting the descriptors won't work if 938 * ttyfd happens to be one of those. 939 */ 940 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 941 dup2(fd, STDIN_FILENO); 942 dup2(fd, STDOUT_FILENO); 943 if (fd > STDOUT_FILENO) 944 close(fd); 945 } 946 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 947 } 948 949 /* 950 * Listen for TCP connections 951 */ 952 static void 953 server_listen(void) 954 { 955 int ret, listen_sock, on = 1; 956 struct addrinfo *ai; 957 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 958 959 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 960 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 961 continue; 962 if (num_listen_socks >= MAX_LISTEN_SOCKS) 963 fatal("Too many listen sockets. " 964 "Enlarge MAX_LISTEN_SOCKS"); 965 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 966 ntop, sizeof(ntop), strport, sizeof(strport), 967 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 968 error("getnameinfo failed: %.100s", 969 ssh_gai_strerror(ret)); 970 continue; 971 } 972 /* Create socket for listening. */ 973 listen_sock = socket(ai->ai_family, ai->ai_socktype, 974 ai->ai_protocol); 975 if (listen_sock < 0) { 976 /* kernel may not support ipv6 */ 977 verbose("socket: %.100s", strerror(errno)); 978 continue; 979 } 980 if (set_nonblock(listen_sock) == -1) { 981 close(listen_sock); 982 continue; 983 } 984 /* 985 * Set socket options. 986 * Allow local port reuse in TIME_WAIT. 987 */ 988 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 989 &on, sizeof(on)) == -1) 990 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 991 992 #ifdef IPV6_V6ONLY 993 /* Only communicate in IPv6 over AF_INET6 sockets. */ 994 if (ai->ai_family == AF_INET6) { 995 if (setsockopt(listen_sock, IPPROTO_IPV6, IPV6_V6ONLY, 996 &on, sizeof(on)) == -1) 997 error("setsockopt IPV6_V6ONLY: %s", 998 strerror(errno)); 999 } 1000 #endif 1001 1002 debug("Bind to port %s on %s.", strport, ntop); 1003 1004 /* Bind the socket to the desired port. */ 1005 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1006 error("Bind to port %s on %s failed: %.200s.", 1007 strport, ntop, strerror(errno)); 1008 close(listen_sock); 1009 continue; 1010 } 1011 listen_socks[num_listen_socks] = listen_sock; 1012 num_listen_socks++; 1013 1014 /* Start listening on the port. */ 1015 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1016 fatal("listen on [%s]:%s: %.100s", 1017 ntop, strport, strerror(errno)); 1018 logit("Server listening on %s port %s.", ntop, strport); 1019 } 1020 freeaddrinfo(options.listen_addrs); 1021 1022 if (!num_listen_socks) 1023 fatal("Cannot bind any address."); 1024 } 1025 1026 /* 1027 * The main TCP accept loop. Note that, for the non-debug case, returns 1028 * from this function are in a forked subprocess. 1029 */ 1030 static void 1031 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1032 { 1033 fd_set *fdset; 1034 int i, j, ret, maxfd; 1035 int key_used = 0, startups = 0; 1036 int startup_p[2] = { -1 , -1 }; 1037 struct sockaddr_storage from; 1038 socklen_t fromlen; 1039 pid_t pid; 1040 1041 /* setup fd set for accept */ 1042 fdset = NULL; 1043 maxfd = 0; 1044 for (i = 0; i < num_listen_socks; i++) 1045 if (listen_socks[i] > maxfd) 1046 maxfd = listen_socks[i]; 1047 /* pipes connected to unauthenticated childs */ 1048 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1049 for (i = 0; i < options.max_startups; i++) 1050 startup_pipes[i] = -1; 1051 1052 /* 1053 * Stay listening for connections until the system crashes or 1054 * the daemon is killed with a signal. 1055 */ 1056 for (;;) { 1057 if (received_sighup) 1058 sighup_restart(); 1059 if (fdset != NULL) 1060 xfree(fdset); 1061 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1062 sizeof(fd_mask)); 1063 1064 for (i = 0; i < num_listen_socks; i++) 1065 FD_SET(listen_socks[i], fdset); 1066 for (i = 0; i < options.max_startups; i++) 1067 if (startup_pipes[i] != -1) 1068 FD_SET(startup_pipes[i], fdset); 1069 1070 /* Wait in select until there is a connection. */ 1071 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1072 if (ret < 0 && errno != EINTR) 1073 error("select: %.100s", strerror(errno)); 1074 if (received_sigterm) { 1075 logit("Received signal %d; terminating.", 1076 (int) received_sigterm); 1077 close_listen_socks(); 1078 unlink(options.pid_file); 1079 exit(255); 1080 } 1081 if (key_used && key_do_regen) { 1082 generate_ephemeral_server_key(); 1083 key_used = 0; 1084 key_do_regen = 0; 1085 } 1086 if (ret < 0) 1087 continue; 1088 1089 for (i = 0; i < options.max_startups; i++) 1090 if (startup_pipes[i] != -1 && 1091 FD_ISSET(startup_pipes[i], fdset)) { 1092 /* 1093 * the read end of the pipe is ready 1094 * if the child has closed the pipe 1095 * after successful authentication 1096 * or if the child has died 1097 */ 1098 close(startup_pipes[i]); 1099 startup_pipes[i] = -1; 1100 startups--; 1101 } 1102 for (i = 0; i < num_listen_socks; i++) { 1103 if (!FD_ISSET(listen_socks[i], fdset)) 1104 continue; 1105 fromlen = sizeof(from); 1106 *newsock = accept(listen_socks[i], 1107 (struct sockaddr *)&from, &fromlen); 1108 if (*newsock < 0) { 1109 if (errno != EINTR && errno != EAGAIN && 1110 errno != EWOULDBLOCK) 1111 error("accept: %.100s", strerror(errno)); 1112 continue; 1113 } 1114 if (unset_nonblock(*newsock) == -1) { 1115 close(*newsock); 1116 continue; 1117 } 1118 if (drop_connection(startups) == 1) { 1119 debug("drop connection #%d", startups); 1120 close(*newsock); 1121 continue; 1122 } 1123 if (pipe(startup_p) == -1) { 1124 close(*newsock); 1125 continue; 1126 } 1127 1128 if (rexec_flag && socketpair(AF_UNIX, 1129 SOCK_STREAM, 0, config_s) == -1) { 1130 error("reexec socketpair: %s", 1131 strerror(errno)); 1132 close(*newsock); 1133 close(startup_p[0]); 1134 close(startup_p[1]); 1135 continue; 1136 } 1137 1138 for (j = 0; j < options.max_startups; j++) 1139 if (startup_pipes[j] == -1) { 1140 startup_pipes[j] = startup_p[0]; 1141 if (maxfd < startup_p[0]) 1142 maxfd = startup_p[0]; 1143 startups++; 1144 break; 1145 } 1146 1147 /* 1148 * Got connection. Fork a child to handle it, unless 1149 * we are in debugging mode. 1150 */ 1151 if (debug_flag) { 1152 /* 1153 * In debugging mode. Close the listening 1154 * socket, and start processing the 1155 * connection without forking. 1156 */ 1157 debug("Server will not fork when running in debugging mode."); 1158 close_listen_socks(); 1159 *sock_in = *newsock; 1160 *sock_out = *newsock; 1161 close(startup_p[0]); 1162 close(startup_p[1]); 1163 startup_pipe = -1; 1164 pid = getpid(); 1165 if (rexec_flag) { 1166 send_rexec_state(config_s[0], 1167 &cfg); 1168 close(config_s[0]); 1169 } 1170 break; 1171 } 1172 1173 /* 1174 * Normal production daemon. Fork, and have 1175 * the child process the connection. The 1176 * parent continues listening. 1177 */ 1178 platform_pre_fork(); 1179 if ((pid = fork()) == 0) { 1180 /* 1181 * Child. Close the listening and 1182 * max_startup sockets. Start using 1183 * the accepted socket. Reinitialize 1184 * logging (since our pid has changed). 1185 * We break out of the loop to handle 1186 * the connection. 1187 */ 1188 platform_post_fork_child(); 1189 startup_pipe = startup_p[1]; 1190 close_startup_pipes(); 1191 close_listen_socks(); 1192 *sock_in = *newsock; 1193 *sock_out = *newsock; 1194 log_init(__progname, 1195 options.log_level, 1196 options.log_facility, 1197 log_stderr); 1198 if (rexec_flag) 1199 close(config_s[0]); 1200 break; 1201 } 1202 1203 /* Parent. Stay in the loop. */ 1204 platform_post_fork_parent(pid); 1205 if (pid < 0) 1206 error("fork: %.100s", strerror(errno)); 1207 else 1208 debug("Forked child %ld.", (long)pid); 1209 1210 close(startup_p[1]); 1211 1212 if (rexec_flag) { 1213 send_rexec_state(config_s[0], &cfg); 1214 close(config_s[0]); 1215 close(config_s[1]); 1216 } 1217 1218 /* 1219 * Mark that the key has been used (it 1220 * was "given" to the child). 1221 */ 1222 if ((options.protocol & SSH_PROTO_1) && 1223 key_used == 0) { 1224 /* Schedule server key regeneration alarm. */ 1225 signal(SIGALRM, key_regeneration_alarm); 1226 alarm(options.key_regeneration_time); 1227 key_used = 1; 1228 } 1229 1230 close(*newsock); 1231 1232 /* 1233 * Ensure that our random state differs 1234 * from that of the child 1235 */ 1236 arc4random_stir(); 1237 } 1238 1239 /* child process check (or debug mode) */ 1240 if (num_listen_socks < 0) 1241 break; 1242 } 1243 } 1244 1245 1246 /* 1247 * Main program for the daemon. 1248 */ 1249 int 1250 main(int ac, char **av) 1251 { 1252 extern char *optarg; 1253 extern int optind; 1254 int opt, i, on = 1; 1255 int sock_in = -1, sock_out = -1, newsock = -1; 1256 const char *remote_ip; 1257 char *test_user = NULL, *test_host = NULL, *test_addr = NULL; 1258 int remote_port; 1259 char *line, *p, *cp; 1260 int config_s[2] = { -1 , -1 }; 1261 u_int64_t ibytes, obytes; 1262 mode_t new_umask; 1263 Key *key; 1264 Authctxt *authctxt; 1265 1266 #ifdef HAVE_SECUREWARE 1267 (void)set_auth_parameters(ac, av); 1268 #endif 1269 __progname = ssh_get_progname(av[0]); 1270 init_rng(); 1271 1272 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1273 saved_argc = ac; 1274 rexec_argc = ac; 1275 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1276 for (i = 0; i < ac; i++) 1277 saved_argv[i] = xstrdup(av[i]); 1278 saved_argv[i] = NULL; 1279 1280 #ifndef HAVE_SETPROCTITLE 1281 /* Prepare for later setproctitle emulation */ 1282 compat_init_setproctitle(ac, av); 1283 av = saved_argv; 1284 #endif 1285 1286 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1287 debug("setgroups(): %.200s", strerror(errno)); 1288 1289 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1290 sanitise_stdfd(); 1291 1292 /* Initialize configuration options to their default values. */ 1293 initialize_server_options(&options); 1294 1295 /* Parse command-line arguments. */ 1296 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) { 1297 switch (opt) { 1298 case '4': 1299 options.address_family = AF_INET; 1300 break; 1301 case '6': 1302 options.address_family = AF_INET6; 1303 break; 1304 case 'f': 1305 config_file_name = optarg; 1306 break; 1307 case 'd': 1308 if (debug_flag == 0) { 1309 debug_flag = 1; 1310 options.log_level = SYSLOG_LEVEL_DEBUG1; 1311 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1312 options.log_level++; 1313 break; 1314 case 'D': 1315 no_daemon_flag = 1; 1316 break; 1317 case 'e': 1318 log_stderr = 1; 1319 break; 1320 case 'i': 1321 inetd_flag = 1; 1322 break; 1323 case 'r': 1324 rexec_flag = 0; 1325 break; 1326 case 'R': 1327 rexeced_flag = 1; 1328 inetd_flag = 1; 1329 break; 1330 case 'Q': 1331 /* ignored */ 1332 break; 1333 case 'q': 1334 options.log_level = SYSLOG_LEVEL_QUIET; 1335 break; 1336 case 'b': 1337 options.server_key_bits = (int)strtonum(optarg, 256, 1338 32768, NULL); 1339 break; 1340 case 'p': 1341 options.ports_from_cmdline = 1; 1342 if (options.num_ports >= MAX_PORTS) { 1343 fprintf(stderr, "too many ports.\n"); 1344 exit(1); 1345 } 1346 options.ports[options.num_ports++] = a2port(optarg); 1347 if (options.ports[options.num_ports-1] <= 0) { 1348 fprintf(stderr, "Bad port number.\n"); 1349 exit(1); 1350 } 1351 break; 1352 case 'g': 1353 if ((options.login_grace_time = convtime(optarg)) == -1) { 1354 fprintf(stderr, "Invalid login grace time.\n"); 1355 exit(1); 1356 } 1357 break; 1358 case 'k': 1359 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1360 fprintf(stderr, "Invalid key regeneration interval.\n"); 1361 exit(1); 1362 } 1363 break; 1364 case 'h': 1365 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1366 fprintf(stderr, "too many host keys.\n"); 1367 exit(1); 1368 } 1369 options.host_key_files[options.num_host_key_files++] = optarg; 1370 break; 1371 case 't': 1372 test_flag = 1; 1373 break; 1374 case 'T': 1375 test_flag = 2; 1376 break; 1377 case 'C': 1378 cp = optarg; 1379 while ((p = strsep(&cp, ",")) && *p != '\0') { 1380 if (strncmp(p, "addr=", 5) == 0) 1381 test_addr = xstrdup(p + 5); 1382 else if (strncmp(p, "host=", 5) == 0) 1383 test_host = xstrdup(p + 5); 1384 else if (strncmp(p, "user=", 5) == 0) 1385 test_user = xstrdup(p + 5); 1386 else { 1387 fprintf(stderr, "Invalid test " 1388 "mode specification %s\n", p); 1389 exit(1); 1390 } 1391 } 1392 break; 1393 case 'u': 1394 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1395 if (utmp_len > MAXHOSTNAMELEN) { 1396 fprintf(stderr, "Invalid utmp length.\n"); 1397 exit(1); 1398 } 1399 break; 1400 case 'o': 1401 line = xstrdup(optarg); 1402 if (process_server_config_line(&options, line, 1403 "command-line", 0, NULL, NULL, NULL, NULL) != 0) 1404 exit(1); 1405 xfree(line); 1406 break; 1407 case '?': 1408 default: 1409 usage(); 1410 break; 1411 } 1412 } 1413 if (rexeced_flag || inetd_flag) 1414 rexec_flag = 0; 1415 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1416 fatal("sshd re-exec requires execution with an absolute path"); 1417 if (rexeced_flag) 1418 closefrom(REEXEC_MIN_FREE_FD); 1419 else 1420 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1421 1422 SSLeay_add_all_algorithms(); 1423 1424 /* 1425 * Force logging to stderr until we have loaded the private host 1426 * key (unless started from inetd) 1427 */ 1428 log_init(__progname, 1429 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1430 SYSLOG_LEVEL_INFO : options.log_level, 1431 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1432 SYSLOG_FACILITY_AUTH : options.log_facility, 1433 log_stderr || !inetd_flag); 1434 1435 /* 1436 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1437 * root's environment 1438 */ 1439 if (getenv("KRB5CCNAME") != NULL) 1440 unsetenv("KRB5CCNAME"); 1441 1442 #ifdef _UNICOS 1443 /* Cray can define user privs drop all privs now! 1444 * Not needed on PRIV_SU systems! 1445 */ 1446 drop_cray_privs(); 1447 #endif 1448 1449 sensitive_data.server_key = NULL; 1450 sensitive_data.ssh1_host_key = NULL; 1451 sensitive_data.have_ssh1_key = 0; 1452 sensitive_data.have_ssh2_key = 0; 1453 1454 /* 1455 * If we're doing an extended config test, make sure we have all of 1456 * the parameters we need. If we're not doing an extended test, 1457 * do not silently ignore connection test params. 1458 */ 1459 if (test_flag >= 2 && 1460 (test_user != NULL || test_host != NULL || test_addr != NULL) 1461 && (test_user == NULL || test_host == NULL || test_addr == NULL)) 1462 fatal("user, host and addr are all required when testing " 1463 "Match configs"); 1464 if (test_flag < 2 && (test_user != NULL || test_host != NULL || 1465 test_addr != NULL)) 1466 fatal("Config test connection parameter (-C) provided without " 1467 "test mode (-T)"); 1468 1469 /* Fetch our configuration */ 1470 buffer_init(&cfg); 1471 if (rexeced_flag) 1472 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1473 else 1474 load_server_config(config_file_name, &cfg); 1475 1476 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1477 &cfg, NULL, NULL, NULL); 1478 1479 seed_rng(); 1480 1481 /* Fill in default values for those options not explicitly set. */ 1482 fill_default_server_options(&options); 1483 1484 /* challenge-response is implemented via keyboard interactive */ 1485 if (options.challenge_response_authentication) 1486 options.kbd_interactive_authentication = 1; 1487 1488 /* set default channel AF */ 1489 channel_set_af(options.address_family); 1490 1491 /* Check that there are no remaining arguments. */ 1492 if (optind < ac) { 1493 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1494 exit(1); 1495 } 1496 1497 debug("sshd version %.100s", SSH_RELEASE); 1498 1499 /* Store privilege separation user for later use if required. */ 1500 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1501 if (use_privsep || options.kerberos_authentication) 1502 fatal("Privilege separation user %s does not exist", 1503 SSH_PRIVSEP_USER); 1504 } else { 1505 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd)); 1506 privsep_pw = pwcopy(privsep_pw); 1507 xfree(privsep_pw->pw_passwd); 1508 privsep_pw->pw_passwd = xstrdup("*"); 1509 } 1510 endpwent(); 1511 1512 /* load private host keys */ 1513 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1514 sizeof(Key *)); 1515 for (i = 0; i < options.num_host_key_files; i++) 1516 sensitive_data.host_keys[i] = NULL; 1517 1518 for (i = 0; i < options.num_host_key_files; i++) { 1519 key = key_load_private(options.host_key_files[i], "", NULL); 1520 sensitive_data.host_keys[i] = key; 1521 if (key == NULL) { 1522 error("Could not load host key: %s", 1523 options.host_key_files[i]); 1524 sensitive_data.host_keys[i] = NULL; 1525 continue; 1526 } 1527 switch (key->type) { 1528 case KEY_RSA1: 1529 sensitive_data.ssh1_host_key = key; 1530 sensitive_data.have_ssh1_key = 1; 1531 break; 1532 case KEY_RSA: 1533 case KEY_DSA: 1534 sensitive_data.have_ssh2_key = 1; 1535 break; 1536 } 1537 debug("private host key: #%d type %d %s", i, key->type, 1538 key_type(key)); 1539 } 1540 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1541 logit("Disabling protocol version 1. Could not load host key"); 1542 options.protocol &= ~SSH_PROTO_1; 1543 } 1544 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1545 logit("Disabling protocol version 2. Could not load host key"); 1546 options.protocol &= ~SSH_PROTO_2; 1547 } 1548 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1549 logit("sshd: no hostkeys available -- exiting."); 1550 exit(1); 1551 } 1552 1553 /* Check certain values for sanity. */ 1554 if (options.protocol & SSH_PROTO_1) { 1555 if (options.server_key_bits < 512 || 1556 options.server_key_bits > 32768) { 1557 fprintf(stderr, "Bad server key size.\n"); 1558 exit(1); 1559 } 1560 /* 1561 * Check that server and host key lengths differ sufficiently. This 1562 * is necessary to make double encryption work with rsaref. Oh, I 1563 * hate software patents. I dont know if this can go? Niels 1564 */ 1565 if (options.server_key_bits > 1566 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1567 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1568 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1569 SSH_KEY_BITS_RESERVED) { 1570 options.server_key_bits = 1571 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1572 SSH_KEY_BITS_RESERVED; 1573 debug("Forcing server key to %d bits to make it differ from host key.", 1574 options.server_key_bits); 1575 } 1576 } 1577 1578 if (use_privsep) { 1579 struct stat st; 1580 1581 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1582 (S_ISDIR(st.st_mode) == 0)) 1583 fatal("Missing privilege separation directory: %s", 1584 _PATH_PRIVSEP_CHROOT_DIR); 1585 1586 #ifdef HAVE_CYGWIN 1587 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1588 (st.st_uid != getuid () || 1589 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1590 #else 1591 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1592 #endif 1593 fatal("%s must be owned by root and not group or " 1594 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1595 } 1596 1597 if (test_flag > 1) { 1598 if (test_user != NULL && test_addr != NULL && test_host != NULL) 1599 parse_server_match_config(&options, test_user, 1600 test_host, test_addr); 1601 dump_config(&options); 1602 } 1603 1604 /* Configuration looks good, so exit if in test mode. */ 1605 if (test_flag) 1606 exit(0); 1607 1608 /* 1609 * Clear out any supplemental groups we may have inherited. This 1610 * prevents inadvertent creation of files with bad modes (in the 1611 * portable version at least, it's certainly possible for PAM 1612 * to create a file, and we can't control the code in every 1613 * module which might be used). 1614 */ 1615 if (setgroups(0, NULL) < 0) 1616 debug("setgroups() failed: %.200s", strerror(errno)); 1617 1618 if (rexec_flag) { 1619 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1620 for (i = 0; i < rexec_argc; i++) { 1621 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1622 rexec_argv[i] = saved_argv[i]; 1623 } 1624 rexec_argv[rexec_argc] = "-R"; 1625 rexec_argv[rexec_argc + 1] = NULL; 1626 } 1627 1628 /* Ensure that umask disallows at least group and world write */ 1629 new_umask = umask(0077) | 0022; 1630 (void) umask(new_umask); 1631 1632 /* Initialize the log (it is reinitialized below in case we forked). */ 1633 if (debug_flag && (!inetd_flag || rexeced_flag)) 1634 log_stderr = 1; 1635 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1636 1637 /* 1638 * If not in debugging mode, and not started from inetd, disconnect 1639 * from the controlling terminal, and fork. The original process 1640 * exits. 1641 */ 1642 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1643 #ifdef TIOCNOTTY 1644 int fd; 1645 #endif /* TIOCNOTTY */ 1646 if (daemon(0, 0) < 0) 1647 fatal("daemon() failed: %.200s", strerror(errno)); 1648 1649 /* Disconnect from the controlling tty. */ 1650 #ifdef TIOCNOTTY 1651 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1652 if (fd >= 0) { 1653 (void) ioctl(fd, TIOCNOTTY, NULL); 1654 close(fd); 1655 } 1656 #endif /* TIOCNOTTY */ 1657 } 1658 /* Reinitialize the log (because of the fork above). */ 1659 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1660 1661 /* Initialize the random number generator. */ 1662 arc4random_stir(); 1663 1664 /* Chdir to the root directory so that the current disk can be 1665 unmounted if desired. */ 1666 chdir("/"); 1667 1668 /* ignore SIGPIPE */ 1669 signal(SIGPIPE, SIG_IGN); 1670 1671 /* Get a connection, either from inetd or a listening TCP socket */ 1672 if (inetd_flag) { 1673 server_accept_inetd(&sock_in, &sock_out); 1674 } else { 1675 server_listen(); 1676 1677 if (options.protocol & SSH_PROTO_1) 1678 generate_ephemeral_server_key(); 1679 1680 signal(SIGHUP, sighup_handler); 1681 signal(SIGCHLD, main_sigchld_handler); 1682 signal(SIGTERM, sigterm_handler); 1683 signal(SIGQUIT, sigterm_handler); 1684 1685 /* 1686 * Write out the pid file after the sigterm handler 1687 * is setup and the listen sockets are bound 1688 */ 1689 if (!debug_flag) { 1690 FILE *f = fopen(options.pid_file, "w"); 1691 1692 if (f == NULL) { 1693 error("Couldn't create pid file \"%s\": %s", 1694 options.pid_file, strerror(errno)); 1695 } else { 1696 fprintf(f, "%ld\n", (long) getpid()); 1697 fclose(f); 1698 } 1699 } 1700 1701 /* Accept a connection and return in a forked child */ 1702 server_accept_loop(&sock_in, &sock_out, 1703 &newsock, config_s); 1704 } 1705 1706 /* This is the child processing a new connection. */ 1707 setproctitle("%s", "[accepted]"); 1708 1709 /* 1710 * Create a new session and process group since the 4.4BSD 1711 * setlogin() affects the entire process group. We don't 1712 * want the child to be able to affect the parent. 1713 */ 1714 #if !defined(SSHD_ACQUIRES_CTTY) 1715 /* 1716 * If setsid is called, on some platforms sshd will later acquire a 1717 * controlling terminal which will result in "could not set 1718 * controlling tty" errors. 1719 */ 1720 if (!debug_flag && !inetd_flag && setsid() < 0) 1721 error("setsid: %.100s", strerror(errno)); 1722 #endif 1723 1724 if (rexec_flag) { 1725 int fd; 1726 1727 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1728 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1729 dup2(newsock, STDIN_FILENO); 1730 dup2(STDIN_FILENO, STDOUT_FILENO); 1731 if (startup_pipe == -1) 1732 close(REEXEC_STARTUP_PIPE_FD); 1733 else 1734 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1735 1736 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1737 close(config_s[1]); 1738 if (startup_pipe != -1) 1739 close(startup_pipe); 1740 1741 execv(rexec_argv[0], rexec_argv); 1742 1743 /* Reexec has failed, fall back and continue */ 1744 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1745 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1746 log_init(__progname, options.log_level, 1747 options.log_facility, log_stderr); 1748 1749 /* Clean up fds */ 1750 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1751 close(config_s[1]); 1752 close(REEXEC_CONFIG_PASS_FD); 1753 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1754 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1755 dup2(fd, STDIN_FILENO); 1756 dup2(fd, STDOUT_FILENO); 1757 if (fd > STDERR_FILENO) 1758 close(fd); 1759 } 1760 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1761 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1762 } 1763 1764 /* 1765 * Disable the key regeneration alarm. We will not regenerate the 1766 * key since we are no longer in a position to give it to anyone. We 1767 * will not restart on SIGHUP since it no longer makes sense. 1768 */ 1769 alarm(0); 1770 signal(SIGALRM, SIG_DFL); 1771 signal(SIGHUP, SIG_DFL); 1772 signal(SIGTERM, SIG_DFL); 1773 signal(SIGQUIT, SIG_DFL); 1774 signal(SIGCHLD, SIG_DFL); 1775 signal(SIGINT, SIG_DFL); 1776 1777 #ifdef __FreeBSD__ 1778 /* 1779 * Initialize the resolver. This may not happen automatically 1780 * before privsep chroot(). 1781 */ 1782 if ((_res.options & RES_INIT) == 0) { 1783 debug("res_init()"); 1784 res_init(); 1785 } 1786 #ifdef GSSAPI 1787 /* 1788 * Force GSS-API to parse its configuration and load any 1789 * mechanism plugins. 1790 */ 1791 { 1792 gss_OID_set mechs; 1793 OM_uint32 minor_status; 1794 gss_indicate_mechs(&minor_status, &mechs); 1795 gss_release_oid_set(&minor_status, &mechs); 1796 } 1797 #endif 1798 #endif 1799 1800 /* 1801 * Register our connection. This turns encryption off because we do 1802 * not have a key. 1803 */ 1804 packet_set_connection(sock_in, sock_out); 1805 packet_set_server(); 1806 1807 /* Set SO_KEEPALIVE if requested. */ 1808 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1809 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1810 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1811 1812 if ((remote_port = get_remote_port()) < 0) { 1813 debug("get_remote_port failed"); 1814 cleanup_exit(255); 1815 } 1816 1817 /* 1818 * We use get_canonical_hostname with usedns = 0 instead of 1819 * get_remote_ipaddr here so IP options will be checked. 1820 */ 1821 (void) get_canonical_hostname(0); 1822 /* 1823 * The rest of the code depends on the fact that 1824 * get_remote_ipaddr() caches the remote ip, even if 1825 * the socket goes away. 1826 */ 1827 remote_ip = get_remote_ipaddr(); 1828 1829 #ifdef SSH_AUDIT_EVENTS 1830 audit_connection_from(remote_ip, remote_port); 1831 #endif 1832 #ifdef LIBWRAP 1833 allow_severity = options.log_facility|LOG_INFO; 1834 deny_severity = options.log_facility|LOG_WARNING; 1835 /* Check whether logins are denied from this host. */ 1836 if (packet_connection_is_on_socket()) { 1837 struct request_info req; 1838 1839 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 1840 fromhost(&req); 1841 1842 if (!hosts_access(&req)) { 1843 debug("Connection refused by tcp wrapper"); 1844 refuse(&req); 1845 /* NOTREACHED */ 1846 fatal("libwrap refuse returns"); 1847 } 1848 } 1849 #endif /* LIBWRAP */ 1850 1851 /* Log the connection. */ 1852 verbose("Connection from %.500s port %d", remote_ip, remote_port); 1853 1854 /* 1855 * We don't want to listen forever unless the other side 1856 * successfully authenticates itself. So we set up an alarm which is 1857 * cleared after successful authentication. A limit of zero 1858 * indicates no limit. Note that we don't set the alarm in debugging 1859 * mode; it is just annoying to have the server exit just when you 1860 * are about to discover the bug. 1861 */ 1862 signal(SIGALRM, grace_alarm_handler); 1863 if (!debug_flag) 1864 alarm(options.login_grace_time); 1865 1866 sshd_exchange_identification(sock_in, sock_out); 1867 1868 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 1869 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 1870 generate_ephemeral_server_key(); 1871 1872 packet_set_nonblocking(); 1873 1874 /* allocate authentication context */ 1875 authctxt = xcalloc(1, sizeof(*authctxt)); 1876 1877 authctxt->loginmsg = &loginmsg; 1878 1879 /* XXX global for cleanup, access from other modules */ 1880 the_authctxt = authctxt; 1881 1882 /* prepare buffer to collect messages to display to user after login */ 1883 buffer_init(&loginmsg); 1884 1885 if (use_privsep) 1886 if (privsep_preauth(authctxt) == 1) 1887 goto authenticated; 1888 1889 /* perform the key exchange */ 1890 /* authenticate user and start session */ 1891 if (compat20) { 1892 do_ssh2_kex(); 1893 do_authentication2(authctxt); 1894 } else { 1895 do_ssh1_kex(); 1896 do_authentication(authctxt); 1897 } 1898 /* 1899 * If we use privilege separation, the unprivileged child transfers 1900 * the current keystate and exits 1901 */ 1902 if (use_privsep) { 1903 mm_send_keystate(pmonitor); 1904 exit(0); 1905 } 1906 1907 authenticated: 1908 /* 1909 * Cancel the alarm we set to limit the time taken for 1910 * authentication. 1911 */ 1912 alarm(0); 1913 signal(SIGALRM, SIG_DFL); 1914 authctxt->authenticated = 1; 1915 if (startup_pipe != -1) { 1916 close(startup_pipe); 1917 startup_pipe = -1; 1918 } 1919 1920 #ifdef SSH_AUDIT_EVENTS 1921 audit_event(SSH_AUTH_SUCCESS); 1922 #endif 1923 1924 #ifdef GSSAPI 1925 if (options.gss_authentication) { 1926 temporarily_use_uid(authctxt->pw); 1927 ssh_gssapi_storecreds(); 1928 restore_uid(); 1929 } 1930 #endif 1931 #ifdef USE_PAM 1932 if (options.use_pam) { 1933 do_pam_setcred(1); 1934 do_pam_session(); 1935 } 1936 #endif 1937 1938 /* 1939 * In privilege separation, we fork another child and prepare 1940 * file descriptor passing. 1941 */ 1942 if (use_privsep) { 1943 privsep_postauth(authctxt); 1944 /* the monitor process [priv] will not return */ 1945 if (!compat20) 1946 destroy_sensitive_data(); 1947 } 1948 1949 packet_set_timeout(options.client_alive_interval, 1950 options.client_alive_count_max); 1951 1952 /* Start session. */ 1953 do_authenticated(authctxt); 1954 1955 /* The connection has been terminated. */ 1956 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 1957 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 1958 verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes); 1959 1960 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 1961 1962 #ifdef USE_PAM 1963 if (options.use_pam) 1964 finish_pam(); 1965 #endif /* USE_PAM */ 1966 1967 #ifdef SSH_AUDIT_EVENTS 1968 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 1969 #endif 1970 1971 packet_close(); 1972 1973 if (use_privsep) 1974 mm_terminate(); 1975 1976 exit(0); 1977 } 1978 1979 /* 1980 * Decrypt session_key_int using our private server key and private host key 1981 * (key with larger modulus first). 1982 */ 1983 int 1984 ssh1_session_key(BIGNUM *session_key_int) 1985 { 1986 int rsafail = 0; 1987 1988 if (BN_cmp(sensitive_data.server_key->rsa->n, 1989 sensitive_data.ssh1_host_key->rsa->n) > 0) { 1990 /* Server key has bigger modulus. */ 1991 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 1992 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1993 SSH_KEY_BITS_RESERVED) { 1994 fatal("do_connection: %s: " 1995 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 1996 get_remote_ipaddr(), 1997 BN_num_bits(sensitive_data.server_key->rsa->n), 1998 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 1999 SSH_KEY_BITS_RESERVED); 2000 } 2001 if (rsa_private_decrypt(session_key_int, session_key_int, 2002 sensitive_data.server_key->rsa) <= 0) 2003 rsafail++; 2004 if (rsa_private_decrypt(session_key_int, session_key_int, 2005 sensitive_data.ssh1_host_key->rsa) <= 0) 2006 rsafail++; 2007 } else { 2008 /* Host key has bigger modulus (or they are equal). */ 2009 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2010 BN_num_bits(sensitive_data.server_key->rsa->n) + 2011 SSH_KEY_BITS_RESERVED) { 2012 fatal("do_connection: %s: " 2013 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2014 get_remote_ipaddr(), 2015 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2016 BN_num_bits(sensitive_data.server_key->rsa->n), 2017 SSH_KEY_BITS_RESERVED); 2018 } 2019 if (rsa_private_decrypt(session_key_int, session_key_int, 2020 sensitive_data.ssh1_host_key->rsa) < 0) 2021 rsafail++; 2022 if (rsa_private_decrypt(session_key_int, session_key_int, 2023 sensitive_data.server_key->rsa) < 0) 2024 rsafail++; 2025 } 2026 return (rsafail); 2027 } 2028 /* 2029 * SSH1 key exchange 2030 */ 2031 static void 2032 do_ssh1_kex(void) 2033 { 2034 int i, len; 2035 int rsafail = 0; 2036 BIGNUM *session_key_int; 2037 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2038 u_char cookie[8]; 2039 u_int cipher_type, auth_mask, protocol_flags; 2040 2041 /* 2042 * Generate check bytes that the client must send back in the user 2043 * packet in order for it to be accepted; this is used to defy ip 2044 * spoofing attacks. Note that this only works against somebody 2045 * doing IP spoofing from a remote machine; any machine on the local 2046 * network can still see outgoing packets and catch the random 2047 * cookie. This only affects rhosts authentication, and this is one 2048 * of the reasons why it is inherently insecure. 2049 */ 2050 arc4random_buf(cookie, sizeof(cookie)); 2051 2052 /* 2053 * Send our public key. We include in the packet 64 bits of random 2054 * data that must be matched in the reply in order to prevent IP 2055 * spoofing. 2056 */ 2057 packet_start(SSH_SMSG_PUBLIC_KEY); 2058 for (i = 0; i < 8; i++) 2059 packet_put_char(cookie[i]); 2060 2061 /* Store our public server RSA key. */ 2062 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2063 packet_put_bignum(sensitive_data.server_key->rsa->e); 2064 packet_put_bignum(sensitive_data.server_key->rsa->n); 2065 2066 /* Store our public host RSA key. */ 2067 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2068 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2069 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2070 2071 /* Put protocol flags. */ 2072 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2073 2074 /* Declare which ciphers we support. */ 2075 packet_put_int(cipher_mask_ssh1(0)); 2076 2077 /* Declare supported authentication types. */ 2078 auth_mask = 0; 2079 if (options.rhosts_rsa_authentication) 2080 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2081 if (options.rsa_authentication) 2082 auth_mask |= 1 << SSH_AUTH_RSA; 2083 if (options.challenge_response_authentication == 1) 2084 auth_mask |= 1 << SSH_AUTH_TIS; 2085 if (options.password_authentication) 2086 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2087 packet_put_int(auth_mask); 2088 2089 /* Send the packet and wait for it to be sent. */ 2090 packet_send(); 2091 packet_write_wait(); 2092 2093 debug("Sent %d bit server key and %d bit host key.", 2094 BN_num_bits(sensitive_data.server_key->rsa->n), 2095 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2096 2097 /* Read clients reply (cipher type and session key). */ 2098 packet_read_expect(SSH_CMSG_SESSION_KEY); 2099 2100 /* Get cipher type and check whether we accept this. */ 2101 cipher_type = packet_get_char(); 2102 2103 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2104 packet_disconnect("Warning: client selects unsupported cipher."); 2105 2106 /* Get check bytes from the packet. These must match those we 2107 sent earlier with the public key packet. */ 2108 for (i = 0; i < 8; i++) 2109 if (cookie[i] != packet_get_char()) 2110 packet_disconnect("IP Spoofing check bytes do not match."); 2111 2112 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2113 2114 /* Get the encrypted integer. */ 2115 if ((session_key_int = BN_new()) == NULL) 2116 fatal("do_ssh1_kex: BN_new failed"); 2117 packet_get_bignum(session_key_int); 2118 2119 protocol_flags = packet_get_int(); 2120 packet_set_protocol_flags(protocol_flags); 2121 packet_check_eom(); 2122 2123 /* Decrypt session_key_int using host/server keys */ 2124 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2125 2126 /* 2127 * Extract session key from the decrypted integer. The key is in the 2128 * least significant 256 bits of the integer; the first byte of the 2129 * key is in the highest bits. 2130 */ 2131 if (!rsafail) { 2132 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2133 len = BN_num_bytes(session_key_int); 2134 if (len < 0 || (u_int)len > sizeof(session_key)) { 2135 error("do_ssh1_kex: bad session key len from %s: " 2136 "session_key_int %d > sizeof(session_key) %lu", 2137 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2138 rsafail++; 2139 } else { 2140 memset(session_key, 0, sizeof(session_key)); 2141 BN_bn2bin(session_key_int, 2142 session_key + sizeof(session_key) - len); 2143 2144 derive_ssh1_session_id( 2145 sensitive_data.ssh1_host_key->rsa->n, 2146 sensitive_data.server_key->rsa->n, 2147 cookie, session_id); 2148 /* 2149 * Xor the first 16 bytes of the session key with the 2150 * session id. 2151 */ 2152 for (i = 0; i < 16; i++) 2153 session_key[i] ^= session_id[i]; 2154 } 2155 } 2156 if (rsafail) { 2157 int bytes = BN_num_bytes(session_key_int); 2158 u_char *buf = xmalloc(bytes); 2159 MD5_CTX md; 2160 2161 logit("do_connection: generating a fake encryption key"); 2162 BN_bn2bin(session_key_int, buf); 2163 MD5_Init(&md); 2164 MD5_Update(&md, buf, bytes); 2165 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2166 MD5_Final(session_key, &md); 2167 MD5_Init(&md); 2168 MD5_Update(&md, session_key, 16); 2169 MD5_Update(&md, buf, bytes); 2170 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2171 MD5_Final(session_key + 16, &md); 2172 memset(buf, 0, bytes); 2173 xfree(buf); 2174 for (i = 0; i < 16; i++) 2175 session_id[i] = session_key[i] ^ session_key[i + 16]; 2176 } 2177 /* Destroy the private and public keys. No longer. */ 2178 destroy_sensitive_data(); 2179 2180 if (use_privsep) 2181 mm_ssh1_session_id(session_id); 2182 2183 /* Destroy the decrypted integer. It is no longer needed. */ 2184 BN_clear_free(session_key_int); 2185 2186 /* Set the session key. From this on all communications will be encrypted. */ 2187 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2188 2189 /* Destroy our copy of the session key. It is no longer needed. */ 2190 memset(session_key, 0, sizeof(session_key)); 2191 2192 debug("Received session key; encryption turned on."); 2193 2194 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2195 packet_start(SSH_SMSG_SUCCESS); 2196 packet_send(); 2197 packet_write_wait(); 2198 } 2199 2200 /* 2201 * SSH2 key exchange: diffie-hellman-group1-sha1 2202 */ 2203 static void 2204 do_ssh2_kex(void) 2205 { 2206 Kex *kex; 2207 2208 if (options.ciphers != NULL) { 2209 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2210 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2211 } 2212 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2213 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2214 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2215 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2216 2217 if (options.macs != NULL) { 2218 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2219 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2220 } 2221 if (options.compression == COMP_NONE) { 2222 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2223 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2224 } else if (options.compression == COMP_DELAYED) { 2225 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2226 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2227 } 2228 2229 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); 2230 2231 /* start key exchange */ 2232 kex = kex_setup(myproposal); 2233 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2234 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2235 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2236 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2237 kex->server = 1; 2238 kex->client_version_string=client_version_string; 2239 kex->server_version_string=server_version_string; 2240 kex->load_host_key=&get_hostkey_by_type; 2241 kex->host_key_index=&get_hostkey_index; 2242 2243 xxx_kex = kex; 2244 2245 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2246 2247 session_id2 = kex->session_id; 2248 session_id2_len = kex->session_id_len; 2249 2250 #ifdef DEBUG_KEXDH 2251 /* send 1st encrypted/maced/compressed message */ 2252 packet_start(SSH2_MSG_IGNORE); 2253 packet_put_cstring("markus"); 2254 packet_send(); 2255 packet_write_wait(); 2256 #endif 2257 debug("KEX done"); 2258 } 2259 2260 /* server specific fatal cleanup */ 2261 void 2262 cleanup_exit(int i) 2263 { 2264 if (the_authctxt) 2265 do_cleanup(the_authctxt); 2266 #ifdef SSH_AUDIT_EVENTS 2267 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2268 if (!use_privsep || mm_is_monitor()) 2269 audit_event(SSH_CONNECTION_ABANDON); 2270 #endif 2271 _exit(i); 2272 } 2273