1 /* $OpenBSD: sshd.c,v 1.381 2011/01/11 06:13:10 djm Exp $ */ 2 /* $FreeBSD$ */ 3 /* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * This program is the ssh daemon. It listens for connections from clients, 8 * and performs authentication, executes use commands or shell, and forwards 9 * information to/from the application to the user client over an encrypted 10 * connection. This can also handle forwarding of X11, TCP/IP, and 11 * authentication agent connections. 12 * 13 * As far as I am concerned, the code I have written for this software 14 * can be used freely for any purpose. Any derived versions of this 15 * software must be clearly marked as such, and if the derived work is 16 * incompatible with the protocol description in the RFC file, it must be 17 * called by a name other than "ssh" or "Secure Shell". 18 * 19 * SSH2 implementation: 20 * Privilege Separation: 21 * 22 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 23 * Copyright (c) 2002 Niels Provos. All rights reserved. 24 * 25 * Redistribution and use in source and binary forms, with or without 26 * modification, are permitted provided that the following conditions 27 * are met: 28 * 1. Redistributions of source code must retain the above copyright 29 * notice, this list of conditions and the following disclaimer. 30 * 2. Redistributions in binary form must reproduce the above copyright 31 * notice, this list of conditions and the following disclaimer in the 32 * documentation and/or other materials provided with the distribution. 33 * 34 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 35 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 36 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 37 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 38 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 39 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 40 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 41 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 42 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 43 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 44 */ 45 46 #include "includes.h" 47 __RCSID("$FreeBSD$"); 48 49 #include <sys/types.h> 50 #include <sys/ioctl.h> 51 #include <sys/mman.h> 52 #include <sys/socket.h> 53 #ifdef HAVE_SYS_STAT_H 54 # include <sys/stat.h> 55 #endif 56 #ifdef HAVE_SYS_TIME_H 57 # include <sys/time.h> 58 #endif 59 #include "openbsd-compat/sys-tree.h" 60 #include "openbsd-compat/sys-queue.h" 61 #include <sys/wait.h> 62 63 #include <errno.h> 64 #include <fcntl.h> 65 #include <netdb.h> 66 #ifdef HAVE_PATHS_H 67 #include <paths.h> 68 #endif 69 #include <grp.h> 70 #include <pwd.h> 71 #include <signal.h> 72 #include <stdarg.h> 73 #include <stdio.h> 74 #include <stdlib.h> 75 #include <string.h> 76 #include <unistd.h> 77 78 #include <openssl/dh.h> 79 #include <openssl/bn.h> 80 #include <openssl/md5.h> 81 #include <openssl/rand.h> 82 #include "openbsd-compat/openssl-compat.h" 83 84 #ifdef HAVE_SECUREWARE 85 #include <sys/security.h> 86 #include <prot.h> 87 #endif 88 89 #ifdef __FreeBSD__ 90 #include <resolv.h> 91 #if defined(GSSAPI) && defined(HAVE_GSSAPI_H) 92 #include <gssapi.h> 93 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H) 94 #include <gssapi/gssapi.h> 95 #endif 96 #endif 97 98 #include "xmalloc.h" 99 #include "ssh.h" 100 #include "ssh1.h" 101 #include "ssh2.h" 102 #include "rsa.h" 103 #include "sshpty.h" 104 #include "packet.h" 105 #include "log.h" 106 #include "buffer.h" 107 #include "servconf.h" 108 #include "uidswap.h" 109 #include "compat.h" 110 #include "cipher.h" 111 #include "key.h" 112 #include "kex.h" 113 #include "dh.h" 114 #include "myproposal.h" 115 #include "authfile.h" 116 #include "pathnames.h" 117 #include "atomicio.h" 118 #include "canohost.h" 119 #include "hostfile.h" 120 #include "auth.h" 121 #include "misc.h" 122 #include "msg.h" 123 #include "dispatch.h" 124 #include "channels.h" 125 #include "session.h" 126 #include "monitor_mm.h" 127 #include "monitor.h" 128 #ifdef GSSAPI 129 #include "ssh-gss.h" 130 #endif 131 #include "monitor_wrap.h" 132 #include "roaming.h" 133 #include "version.h" 134 135 #ifdef LIBWRAP 136 #include <tcpd.h> 137 #include <syslog.h> 138 int allow_severity; 139 int deny_severity; 140 #endif /* LIBWRAP */ 141 142 #ifndef O_NOCTTY 143 #define O_NOCTTY 0 144 #endif 145 146 /* Re-exec fds */ 147 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 148 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 149 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 150 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 151 152 extern char *__progname; 153 154 /* Server configuration options. */ 155 ServerOptions options; 156 157 /* Name of the server configuration file. */ 158 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 159 160 /* 161 * Debug mode flag. This can be set on the command line. If debug 162 * mode is enabled, extra debugging output will be sent to the system 163 * log, the daemon will not go to background, and will exit after processing 164 * the first connection. 165 */ 166 int debug_flag = 0; 167 168 /* Flag indicating that the daemon should only test the configuration and keys. */ 169 int test_flag = 0; 170 171 /* Flag indicating that the daemon is being started from inetd. */ 172 int inetd_flag = 0; 173 174 /* Flag indicating that sshd should not detach and become a daemon. */ 175 int no_daemon_flag = 0; 176 177 /* debug goes to stderr unless inetd_flag is set */ 178 int log_stderr = 0; 179 180 /* Saved arguments to main(). */ 181 char **saved_argv; 182 int saved_argc; 183 184 /* re-exec */ 185 int rexeced_flag = 0; 186 int rexec_flag = 1; 187 int rexec_argc = 0; 188 char **rexec_argv; 189 190 /* 191 * The sockets that the server is listening; this is used in the SIGHUP 192 * signal handler. 193 */ 194 #define MAX_LISTEN_SOCKS 16 195 int listen_socks[MAX_LISTEN_SOCKS]; 196 int num_listen_socks = 0; 197 198 /* 199 * the client's version string, passed by sshd2 in compat mode. if != NULL, 200 * sshd will skip the version-number exchange 201 */ 202 char *client_version_string = NULL; 203 char *server_version_string = NULL; 204 205 /* for rekeying XXX fixme */ 206 Kex *xxx_kex; 207 208 /* 209 * Any really sensitive data in the application is contained in this 210 * structure. The idea is that this structure could be locked into memory so 211 * that the pages do not get written into swap. However, there are some 212 * problems. The private key contains BIGNUMs, and we do not (in principle) 213 * have access to the internals of them, and locking just the structure is 214 * not very useful. Currently, memory locking is not implemented. 215 */ 216 struct { 217 Key *server_key; /* ephemeral server key */ 218 Key *ssh1_host_key; /* ssh1 host key */ 219 Key **host_keys; /* all private host keys */ 220 Key **host_certificates; /* all public host certificates */ 221 int have_ssh1_key; 222 int have_ssh2_key; 223 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 224 } sensitive_data; 225 226 /* 227 * Flag indicating whether the RSA server key needs to be regenerated. 228 * Is set in the SIGALRM handler and cleared when the key is regenerated. 229 */ 230 static volatile sig_atomic_t key_do_regen = 0; 231 232 /* This is set to true when a signal is received. */ 233 static volatile sig_atomic_t received_sighup = 0; 234 static volatile sig_atomic_t received_sigterm = 0; 235 236 /* session identifier, used by RSA-auth */ 237 u_char session_id[16]; 238 239 /* same for ssh2 */ 240 u_char *session_id2 = NULL; 241 u_int session_id2_len = 0; 242 243 /* record remote hostname or ip */ 244 u_int utmp_len = MAXHOSTNAMELEN; 245 246 /* options.max_startup sized array of fd ints */ 247 int *startup_pipes = NULL; 248 int startup_pipe; /* in child */ 249 250 /* variables used for privilege separation */ 251 int use_privsep = -1; 252 struct monitor *pmonitor = NULL; 253 254 /* global authentication context */ 255 Authctxt *the_authctxt = NULL; 256 257 /* sshd_config buffer */ 258 Buffer cfg; 259 260 /* message to be displayed after login */ 261 Buffer loginmsg; 262 263 /* Unprivileged user */ 264 struct passwd *privsep_pw = NULL; 265 266 /* Prototypes for various functions defined later in this file. */ 267 void destroy_sensitive_data(void); 268 void demote_sensitive_data(void); 269 270 static void do_ssh1_kex(void); 271 static void do_ssh2_kex(void); 272 273 /* 274 * Close all listening sockets 275 */ 276 static void 277 close_listen_socks(void) 278 { 279 int i; 280 281 for (i = 0; i < num_listen_socks; i++) 282 close(listen_socks[i]); 283 num_listen_socks = -1; 284 } 285 286 static void 287 close_startup_pipes(void) 288 { 289 int i; 290 291 if (startup_pipes) 292 for (i = 0; i < options.max_startups; i++) 293 if (startup_pipes[i] != -1) 294 close(startup_pipes[i]); 295 } 296 297 /* 298 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 299 * the effect is to reread the configuration file (and to regenerate 300 * the server key). 301 */ 302 303 /*ARGSUSED*/ 304 static void 305 sighup_handler(int sig) 306 { 307 int save_errno = errno; 308 309 received_sighup = 1; 310 signal(SIGHUP, sighup_handler); 311 errno = save_errno; 312 } 313 314 /* 315 * Called from the main program after receiving SIGHUP. 316 * Restarts the server. 317 */ 318 static void 319 sighup_restart(void) 320 { 321 logit("Received SIGHUP; restarting."); 322 close_listen_socks(); 323 close_startup_pipes(); 324 alarm(0); /* alarm timer persists across exec */ 325 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 326 execv(saved_argv[0], saved_argv); 327 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 328 strerror(errno)); 329 exit(1); 330 } 331 332 /* 333 * Generic signal handler for terminating signals in the master daemon. 334 */ 335 /*ARGSUSED*/ 336 static void 337 sigterm_handler(int sig) 338 { 339 received_sigterm = sig; 340 } 341 342 /* 343 * SIGCHLD handler. This is called whenever a child dies. This will then 344 * reap any zombies left by exited children. 345 */ 346 /*ARGSUSED*/ 347 static void 348 main_sigchld_handler(int sig) 349 { 350 int save_errno = errno; 351 pid_t pid; 352 int status; 353 354 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 355 (pid < 0 && errno == EINTR)) 356 ; 357 358 signal(SIGCHLD, main_sigchld_handler); 359 errno = save_errno; 360 } 361 362 /* 363 * Signal handler for the alarm after the login grace period has expired. 364 */ 365 /*ARGSUSED*/ 366 static void 367 grace_alarm_handler(int sig) 368 { 369 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 370 kill(pmonitor->m_pid, SIGALRM); 371 372 /* Log error and exit. */ 373 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 374 } 375 376 /* 377 * Signal handler for the key regeneration alarm. Note that this 378 * alarm only occurs in the daemon waiting for connections, and it does not 379 * do anything with the private key or random state before forking. 380 * Thus there should be no concurrency control/asynchronous execution 381 * problems. 382 */ 383 static void 384 generate_ephemeral_server_key(void) 385 { 386 verbose("Generating %s%d bit RSA key.", 387 sensitive_data.server_key ? "new " : "", options.server_key_bits); 388 if (sensitive_data.server_key != NULL) 389 key_free(sensitive_data.server_key); 390 sensitive_data.server_key = key_generate(KEY_RSA1, 391 options.server_key_bits); 392 verbose("RSA key generation complete."); 393 394 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 395 arc4random_stir(); 396 } 397 398 /*ARGSUSED*/ 399 static void 400 key_regeneration_alarm(int sig) 401 { 402 int save_errno = errno; 403 404 signal(SIGALRM, SIG_DFL); 405 errno = save_errno; 406 key_do_regen = 1; 407 } 408 409 static void 410 sshd_exchange_identification(int sock_in, int sock_out) 411 { 412 u_int i; 413 int mismatch; 414 int remote_major, remote_minor; 415 int major, minor; 416 char *s, *newline = "\n"; 417 char buf[256]; /* Must not be larger than remote_version. */ 418 char remote_version[256]; /* Must be at least as big as buf. */ 419 420 if ((options.protocol & SSH_PROTO_1) && 421 (options.protocol & SSH_PROTO_2)) { 422 major = PROTOCOL_MAJOR_1; 423 minor = 99; 424 } else if (options.protocol & SSH_PROTO_2) { 425 major = PROTOCOL_MAJOR_2; 426 minor = PROTOCOL_MINOR_2; 427 newline = "\r\n"; 428 } else { 429 major = PROTOCOL_MAJOR_1; 430 minor = PROTOCOL_MINOR_1; 431 } 432 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor, 433 SSH_RELEASE, newline); 434 server_version_string = xstrdup(buf); 435 436 /* Send our protocol version identification. */ 437 if (roaming_atomicio(vwrite, sock_out, server_version_string, 438 strlen(server_version_string)) 439 != strlen(server_version_string)) { 440 logit("Could not write ident string to %s", get_remote_ipaddr()); 441 cleanup_exit(255); 442 } 443 444 /* Read other sides version identification. */ 445 memset(buf, 0, sizeof(buf)); 446 for (i = 0; i < sizeof(buf) - 1; i++) { 447 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 448 logit("Did not receive identification string from %s", 449 get_remote_ipaddr()); 450 cleanup_exit(255); 451 } 452 if (buf[i] == '\r') { 453 buf[i] = 0; 454 /* Kludge for F-Secure Macintosh < 1.0.2 */ 455 if (i == 12 && 456 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 457 break; 458 continue; 459 } 460 if (buf[i] == '\n') { 461 buf[i] = 0; 462 break; 463 } 464 } 465 buf[sizeof(buf) - 1] = 0; 466 client_version_string = xstrdup(buf); 467 468 /* 469 * Check that the versions match. In future this might accept 470 * several versions and set appropriate flags to handle them. 471 */ 472 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 473 &remote_major, &remote_minor, remote_version) != 3) { 474 s = "Protocol mismatch.\n"; 475 (void) atomicio(vwrite, sock_out, s, strlen(s)); 476 close(sock_in); 477 close(sock_out); 478 logit("Bad protocol version identification '%.100s' from %s", 479 client_version_string, get_remote_ipaddr()); 480 cleanup_exit(255); 481 } 482 debug("Client protocol version %d.%d; client software version %.100s", 483 remote_major, remote_minor, remote_version); 484 485 compat_datafellows(remote_version); 486 487 if (datafellows & SSH_BUG_PROBE) { 488 logit("probed from %s with %s. Don't panic.", 489 get_remote_ipaddr(), client_version_string); 490 cleanup_exit(255); 491 } 492 493 if (datafellows & SSH_BUG_SCANNER) { 494 logit("scanned from %s with %s. Don't panic.", 495 get_remote_ipaddr(), client_version_string); 496 cleanup_exit(255); 497 } 498 499 mismatch = 0; 500 switch (remote_major) { 501 case 1: 502 if (remote_minor == 99) { 503 if (options.protocol & SSH_PROTO_2) 504 enable_compat20(); 505 else 506 mismatch = 1; 507 break; 508 } 509 if (!(options.protocol & SSH_PROTO_1)) { 510 mismatch = 1; 511 break; 512 } 513 if (remote_minor < 3) { 514 packet_disconnect("Your ssh version is too old and " 515 "is no longer supported. Please install a newer version."); 516 } else if (remote_minor == 3) { 517 /* note that this disables agent-forwarding */ 518 enable_compat13(); 519 } 520 break; 521 case 2: 522 if (options.protocol & SSH_PROTO_2) { 523 enable_compat20(); 524 break; 525 } 526 /* FALLTHROUGH */ 527 default: 528 mismatch = 1; 529 break; 530 } 531 chop(server_version_string); 532 debug("Local version string %.200s", server_version_string); 533 534 if (mismatch) { 535 s = "Protocol major versions differ.\n"; 536 (void) atomicio(vwrite, sock_out, s, strlen(s)); 537 close(sock_in); 538 close(sock_out); 539 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 540 get_remote_ipaddr(), 541 server_version_string, client_version_string); 542 cleanup_exit(255); 543 } 544 } 545 546 /* Destroy the host and server keys. They will no longer be needed. */ 547 void 548 destroy_sensitive_data(void) 549 { 550 int i; 551 552 if (sensitive_data.server_key) { 553 key_free(sensitive_data.server_key); 554 sensitive_data.server_key = NULL; 555 } 556 for (i = 0; i < options.num_host_key_files; i++) { 557 if (sensitive_data.host_keys[i]) { 558 key_free(sensitive_data.host_keys[i]); 559 sensitive_data.host_keys[i] = NULL; 560 } 561 if (sensitive_data.host_certificates[i]) { 562 key_free(sensitive_data.host_certificates[i]); 563 sensitive_data.host_certificates[i] = NULL; 564 } 565 } 566 sensitive_data.ssh1_host_key = NULL; 567 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); 568 } 569 570 /* Demote private to public keys for network child */ 571 void 572 demote_sensitive_data(void) 573 { 574 Key *tmp; 575 int i; 576 577 if (sensitive_data.server_key) { 578 tmp = key_demote(sensitive_data.server_key); 579 key_free(sensitive_data.server_key); 580 sensitive_data.server_key = tmp; 581 } 582 583 for (i = 0; i < options.num_host_key_files; i++) { 584 if (sensitive_data.host_keys[i]) { 585 tmp = key_demote(sensitive_data.host_keys[i]); 586 key_free(sensitive_data.host_keys[i]); 587 sensitive_data.host_keys[i] = tmp; 588 if (tmp->type == KEY_RSA1) 589 sensitive_data.ssh1_host_key = tmp; 590 } 591 /* Certs do not need demotion */ 592 } 593 594 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 595 } 596 597 static void 598 privsep_preauth_child(void) 599 { 600 u_int32_t rnd[256]; 601 gid_t gidset[1]; 602 603 /* Enable challenge-response authentication for privilege separation */ 604 privsep_challenge_enable(); 605 606 arc4random_stir(); 607 arc4random_buf(rnd, sizeof(rnd)); 608 RAND_seed(rnd, sizeof(rnd)); 609 610 /* Demote the private keys to public keys. */ 611 demote_sensitive_data(); 612 613 /* Change our root directory */ 614 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 615 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 616 strerror(errno)); 617 if (chdir("/") == -1) 618 fatal("chdir(\"/\"): %s", strerror(errno)); 619 620 /* Drop our privileges */ 621 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 622 (u_int)privsep_pw->pw_gid); 623 #if 0 624 /* XXX not ready, too heavy after chroot */ 625 do_setusercontext(privsep_pw); 626 #else 627 gidset[0] = privsep_pw->pw_gid; 628 if (setgroups(1, gidset) < 0) 629 fatal("setgroups: %.100s", strerror(errno)); 630 permanently_set_uid(privsep_pw); 631 #endif 632 } 633 634 static int 635 privsep_preauth(Authctxt *authctxt) 636 { 637 int status; 638 pid_t pid; 639 640 /* Set up unprivileged child process to deal with network data */ 641 pmonitor = monitor_init(); 642 /* Store a pointer to the kex for later rekeying */ 643 pmonitor->m_pkex = &xxx_kex; 644 645 pid = fork(); 646 if (pid == -1) { 647 fatal("fork of unprivileged child failed"); 648 } else if (pid != 0) { 649 debug2("Network child is on pid %ld", (long)pid); 650 651 close(pmonitor->m_recvfd); 652 pmonitor->m_pid = pid; 653 monitor_child_preauth(authctxt, pmonitor); 654 close(pmonitor->m_sendfd); 655 656 /* Sync memory */ 657 monitor_sync(pmonitor); 658 659 /* Wait for the child's exit status */ 660 while (waitpid(pid, &status, 0) < 0) 661 if (errno != EINTR) 662 break; 663 return (1); 664 } else { 665 /* child */ 666 667 close(pmonitor->m_sendfd); 668 669 /* Demote the child */ 670 if (getuid() == 0 || geteuid() == 0) 671 privsep_preauth_child(); 672 setproctitle("%s", "[net]"); 673 } 674 return (0); 675 } 676 677 static void 678 privsep_postauth(Authctxt *authctxt) 679 { 680 u_int32_t rnd[256]; 681 682 #ifdef DISABLE_FD_PASSING 683 if (1) { 684 #else 685 if (authctxt->pw->pw_uid == 0 || options.use_login) { 686 #endif 687 /* File descriptor passing is broken or root login */ 688 use_privsep = 0; 689 goto skip; 690 } 691 692 /* New socket pair */ 693 monitor_reinit(pmonitor); 694 695 pmonitor->m_pid = fork(); 696 if (pmonitor->m_pid == -1) 697 fatal("fork of unprivileged child failed"); 698 else if (pmonitor->m_pid != 0) { 699 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 700 close(pmonitor->m_recvfd); 701 buffer_clear(&loginmsg); 702 monitor_child_postauth(pmonitor); 703 704 /* NEVERREACHED */ 705 exit(0); 706 } 707 708 close(pmonitor->m_sendfd); 709 710 /* Demote the private keys to public keys. */ 711 demote_sensitive_data(); 712 713 arc4random_stir(); 714 arc4random_buf(rnd, sizeof(rnd)); 715 RAND_seed(rnd, sizeof(rnd)); 716 717 /* Drop privileges */ 718 do_setusercontext(authctxt->pw); 719 720 skip: 721 /* It is safe now to apply the key state */ 722 monitor_apply_keystate(pmonitor); 723 724 /* 725 * Tell the packet layer that authentication was successful, since 726 * this information is not part of the key state. 727 */ 728 packet_set_authenticated(); 729 } 730 731 static char * 732 list_hostkey_types(void) 733 { 734 Buffer b; 735 const char *p; 736 char *ret; 737 int i; 738 Key *key; 739 740 buffer_init(&b); 741 for (i = 0; i < options.num_host_key_files; i++) { 742 key = sensitive_data.host_keys[i]; 743 if (key == NULL) 744 continue; 745 switch (key->type) { 746 case KEY_RSA: 747 case KEY_DSA: 748 case KEY_ECDSA: 749 if (buffer_len(&b) > 0) 750 buffer_append(&b, ",", 1); 751 p = key_ssh_name(key); 752 buffer_append(&b, p, strlen(p)); 753 break; 754 } 755 /* If the private key has a cert peer, then list that too */ 756 key = sensitive_data.host_certificates[i]; 757 if (key == NULL) 758 continue; 759 switch (key->type) { 760 case KEY_RSA_CERT_V00: 761 case KEY_DSA_CERT_V00: 762 case KEY_RSA_CERT: 763 case KEY_DSA_CERT: 764 case KEY_ECDSA_CERT: 765 if (buffer_len(&b) > 0) 766 buffer_append(&b, ",", 1); 767 p = key_ssh_name(key); 768 buffer_append(&b, p, strlen(p)); 769 break; 770 } 771 } 772 buffer_append(&b, "\0", 1); 773 ret = xstrdup(buffer_ptr(&b)); 774 buffer_free(&b); 775 debug("list_hostkey_types: %s", ret); 776 return ret; 777 } 778 779 static Key * 780 get_hostkey_by_type(int type, int need_private) 781 { 782 int i; 783 Key *key; 784 785 for (i = 0; i < options.num_host_key_files; i++) { 786 switch (type) { 787 case KEY_RSA_CERT_V00: 788 case KEY_DSA_CERT_V00: 789 case KEY_RSA_CERT: 790 case KEY_DSA_CERT: 791 case KEY_ECDSA_CERT: 792 key = sensitive_data.host_certificates[i]; 793 break; 794 default: 795 key = sensitive_data.host_keys[i]; 796 break; 797 } 798 if (key != NULL && key->type == type) 799 return need_private ? 800 sensitive_data.host_keys[i] : key; 801 } 802 return NULL; 803 } 804 805 Key * 806 get_hostkey_public_by_type(int type) 807 { 808 return get_hostkey_by_type(type, 0); 809 } 810 811 Key * 812 get_hostkey_private_by_type(int type) 813 { 814 return get_hostkey_by_type(type, 1); 815 } 816 817 Key * 818 get_hostkey_by_index(int ind) 819 { 820 if (ind < 0 || ind >= options.num_host_key_files) 821 return (NULL); 822 return (sensitive_data.host_keys[ind]); 823 } 824 825 int 826 get_hostkey_index(Key *key) 827 { 828 int i; 829 830 for (i = 0; i < options.num_host_key_files; i++) { 831 if (key_is_cert(key)) { 832 if (key == sensitive_data.host_certificates[i]) 833 return (i); 834 } else { 835 if (key == sensitive_data.host_keys[i]) 836 return (i); 837 } 838 } 839 return (-1); 840 } 841 842 /* 843 * returns 1 if connection should be dropped, 0 otherwise. 844 * dropping starts at connection #max_startups_begin with a probability 845 * of (max_startups_rate/100). the probability increases linearly until 846 * all connections are dropped for startups > max_startups 847 */ 848 static int 849 drop_connection(int startups) 850 { 851 int p, r; 852 853 if (startups < options.max_startups_begin) 854 return 0; 855 if (startups >= options.max_startups) 856 return 1; 857 if (options.max_startups_rate == 100) 858 return 1; 859 860 p = 100 - options.max_startups_rate; 861 p *= startups - options.max_startups_begin; 862 p /= options.max_startups - options.max_startups_begin; 863 p += options.max_startups_rate; 864 r = arc4random_uniform(100); 865 866 debug("drop_connection: p %d, r %d", p, r); 867 return (r < p) ? 1 : 0; 868 } 869 870 static void 871 usage(void) 872 { 873 fprintf(stderr, "%s, %s\n", 874 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); 875 fprintf(stderr, 876 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 877 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n" 878 " [-k key_gen_time] [-o option] [-p port] [-u len]\n" 879 ); 880 exit(1); 881 } 882 883 static void 884 send_rexec_state(int fd, Buffer *conf) 885 { 886 Buffer m; 887 888 debug3("%s: entering fd = %d config len %d", __func__, fd, 889 buffer_len(conf)); 890 891 /* 892 * Protocol from reexec master to child: 893 * string configuration 894 * u_int ephemeral_key_follows 895 * bignum e (only if ephemeral_key_follows == 1) 896 * bignum n " 897 * bignum d " 898 * bignum iqmp " 899 * bignum p " 900 * bignum q " 901 * string rngseed (only if OpenSSL is not self-seeded) 902 */ 903 buffer_init(&m); 904 buffer_put_cstring(&m, buffer_ptr(conf)); 905 906 if (sensitive_data.server_key != NULL && 907 sensitive_data.server_key->type == KEY_RSA1) { 908 buffer_put_int(&m, 1); 909 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 910 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 911 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 912 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 913 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 914 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 915 } else 916 buffer_put_int(&m, 0); 917 918 #ifndef OPENSSL_PRNG_ONLY 919 rexec_send_rng_seed(&m); 920 #endif 921 922 if (ssh_msg_send(fd, 0, &m) == -1) 923 fatal("%s: ssh_msg_send failed", __func__); 924 925 buffer_free(&m); 926 927 debug3("%s: done", __func__); 928 } 929 930 static void 931 recv_rexec_state(int fd, Buffer *conf) 932 { 933 Buffer m; 934 char *cp; 935 u_int len; 936 937 debug3("%s: entering fd = %d", __func__, fd); 938 939 buffer_init(&m); 940 941 if (ssh_msg_recv(fd, &m) == -1) 942 fatal("%s: ssh_msg_recv failed", __func__); 943 if (buffer_get_char(&m) != 0) 944 fatal("%s: rexec version mismatch", __func__); 945 946 cp = buffer_get_string(&m, &len); 947 if (conf != NULL) 948 buffer_append(conf, cp, len + 1); 949 xfree(cp); 950 951 if (buffer_get_int(&m)) { 952 if (sensitive_data.server_key != NULL) 953 key_free(sensitive_data.server_key); 954 sensitive_data.server_key = key_new_private(KEY_RSA1); 955 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 956 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 957 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 958 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 959 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 960 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 961 rsa_generate_additional_parameters( 962 sensitive_data.server_key->rsa); 963 } 964 965 #ifndef OPENSSL_PRNG_ONLY 966 rexec_recv_rng_seed(&m); 967 #endif 968 969 buffer_free(&m); 970 971 debug3("%s: done", __func__); 972 } 973 974 /* Accept a connection from inetd */ 975 static void 976 server_accept_inetd(int *sock_in, int *sock_out) 977 { 978 int fd; 979 980 startup_pipe = -1; 981 if (rexeced_flag) { 982 close(REEXEC_CONFIG_PASS_FD); 983 *sock_in = *sock_out = dup(STDIN_FILENO); 984 if (!debug_flag) { 985 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 986 close(REEXEC_STARTUP_PIPE_FD); 987 } 988 } else { 989 *sock_in = dup(STDIN_FILENO); 990 *sock_out = dup(STDOUT_FILENO); 991 } 992 /* 993 * We intentionally do not close the descriptors 0, 1, and 2 994 * as our code for setting the descriptors won't work if 995 * ttyfd happens to be one of those. 996 */ 997 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 998 dup2(fd, STDIN_FILENO); 999 dup2(fd, STDOUT_FILENO); 1000 if (fd > STDOUT_FILENO) 1001 close(fd); 1002 } 1003 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1004 } 1005 1006 /* 1007 * Listen for TCP connections 1008 */ 1009 static void 1010 server_listen(void) 1011 { 1012 int ret, listen_sock, on = 1; 1013 struct addrinfo *ai; 1014 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1015 int socksize; 1016 socklen_t len; 1017 1018 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1019 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1020 continue; 1021 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1022 fatal("Too many listen sockets. " 1023 "Enlarge MAX_LISTEN_SOCKS"); 1024 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1025 ntop, sizeof(ntop), strport, sizeof(strport), 1026 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1027 error("getnameinfo failed: %.100s", 1028 ssh_gai_strerror(ret)); 1029 continue; 1030 } 1031 /* Create socket for listening. */ 1032 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1033 ai->ai_protocol); 1034 if (listen_sock < 0) { 1035 /* kernel may not support ipv6 */ 1036 verbose("socket: %.100s", strerror(errno)); 1037 continue; 1038 } 1039 if (set_nonblock(listen_sock) == -1) { 1040 close(listen_sock); 1041 continue; 1042 } 1043 /* 1044 * Set socket options. 1045 * Allow local port reuse in TIME_WAIT. 1046 */ 1047 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1048 &on, sizeof(on)) == -1) 1049 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1050 1051 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1052 if (ai->ai_family == AF_INET6) 1053 sock_set_v6only(listen_sock); 1054 1055 debug("Bind to port %s on %s.", strport, ntop); 1056 1057 len = sizeof(socksize); 1058 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len); 1059 debug("Server TCP RWIN socket size: %d", socksize); 1060 debug("HPN Buffer Size: %d", options.hpn_buffer_size); 1061 1062 /* Bind the socket to the desired port. */ 1063 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1064 error("Bind to port %s on %s failed: %.200s.", 1065 strport, ntop, strerror(errno)); 1066 close(listen_sock); 1067 continue; 1068 } 1069 listen_socks[num_listen_socks] = listen_sock; 1070 num_listen_socks++; 1071 1072 /* Start listening on the port. */ 1073 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1074 fatal("listen on [%s]:%s: %.100s", 1075 ntop, strport, strerror(errno)); 1076 logit("Server listening on %s port %s.", ntop, strport); 1077 } 1078 freeaddrinfo(options.listen_addrs); 1079 1080 if (!num_listen_socks) 1081 fatal("Cannot bind any address."); 1082 } 1083 1084 /* 1085 * The main TCP accept loop. Note that, for the non-debug case, returns 1086 * from this function are in a forked subprocess. 1087 */ 1088 static void 1089 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1090 { 1091 fd_set *fdset; 1092 int i, j, ret, maxfd; 1093 int key_used = 0, startups = 0; 1094 int startup_p[2] = { -1 , -1 }; 1095 struct sockaddr_storage from; 1096 socklen_t fromlen; 1097 pid_t pid; 1098 1099 /* setup fd set for accept */ 1100 fdset = NULL; 1101 maxfd = 0; 1102 for (i = 0; i < num_listen_socks; i++) 1103 if (listen_socks[i] > maxfd) 1104 maxfd = listen_socks[i]; 1105 /* pipes connected to unauthenticated childs */ 1106 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1107 for (i = 0; i < options.max_startups; i++) 1108 startup_pipes[i] = -1; 1109 1110 /* 1111 * Stay listening for connections until the system crashes or 1112 * the daemon is killed with a signal. 1113 */ 1114 for (;;) { 1115 if (received_sighup) 1116 sighup_restart(); 1117 if (fdset != NULL) 1118 xfree(fdset); 1119 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1120 sizeof(fd_mask)); 1121 1122 for (i = 0; i < num_listen_socks; i++) 1123 FD_SET(listen_socks[i], fdset); 1124 for (i = 0; i < options.max_startups; i++) 1125 if (startup_pipes[i] != -1) 1126 FD_SET(startup_pipes[i], fdset); 1127 1128 /* Wait in select until there is a connection. */ 1129 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1130 if (ret < 0 && errno != EINTR) 1131 error("select: %.100s", strerror(errno)); 1132 if (received_sigterm) { 1133 logit("Received signal %d; terminating.", 1134 (int) received_sigterm); 1135 close_listen_socks(); 1136 unlink(options.pid_file); 1137 exit(255); 1138 } 1139 if (key_used && key_do_regen) { 1140 generate_ephemeral_server_key(); 1141 key_used = 0; 1142 key_do_regen = 0; 1143 } 1144 if (ret < 0) 1145 continue; 1146 1147 for (i = 0; i < options.max_startups; i++) 1148 if (startup_pipes[i] != -1 && 1149 FD_ISSET(startup_pipes[i], fdset)) { 1150 /* 1151 * the read end of the pipe is ready 1152 * if the child has closed the pipe 1153 * after successful authentication 1154 * or if the child has died 1155 */ 1156 close(startup_pipes[i]); 1157 startup_pipes[i] = -1; 1158 startups--; 1159 } 1160 for (i = 0; i < num_listen_socks; i++) { 1161 if (!FD_ISSET(listen_socks[i], fdset)) 1162 continue; 1163 fromlen = sizeof(from); 1164 *newsock = accept(listen_socks[i], 1165 (struct sockaddr *)&from, &fromlen); 1166 if (*newsock < 0) { 1167 if (errno != EINTR && errno != EAGAIN && 1168 errno != EWOULDBLOCK) 1169 error("accept: %.100s", strerror(errno)); 1170 continue; 1171 } 1172 if (unset_nonblock(*newsock) == -1) { 1173 close(*newsock); 1174 continue; 1175 } 1176 if (drop_connection(startups) == 1) { 1177 debug("drop connection #%d", startups); 1178 close(*newsock); 1179 continue; 1180 } 1181 if (pipe(startup_p) == -1) { 1182 close(*newsock); 1183 continue; 1184 } 1185 1186 if (rexec_flag && socketpair(AF_UNIX, 1187 SOCK_STREAM, 0, config_s) == -1) { 1188 error("reexec socketpair: %s", 1189 strerror(errno)); 1190 close(*newsock); 1191 close(startup_p[0]); 1192 close(startup_p[1]); 1193 continue; 1194 } 1195 1196 for (j = 0; j < options.max_startups; j++) 1197 if (startup_pipes[j] == -1) { 1198 startup_pipes[j] = startup_p[0]; 1199 if (maxfd < startup_p[0]) 1200 maxfd = startup_p[0]; 1201 startups++; 1202 break; 1203 } 1204 1205 /* 1206 * Got connection. Fork a child to handle it, unless 1207 * we are in debugging mode. 1208 */ 1209 if (debug_flag) { 1210 /* 1211 * In debugging mode. Close the listening 1212 * socket, and start processing the 1213 * connection without forking. 1214 */ 1215 debug("Server will not fork when running in debugging mode."); 1216 close_listen_socks(); 1217 *sock_in = *newsock; 1218 *sock_out = *newsock; 1219 close(startup_p[0]); 1220 close(startup_p[1]); 1221 startup_pipe = -1; 1222 pid = getpid(); 1223 if (rexec_flag) { 1224 send_rexec_state(config_s[0], 1225 &cfg); 1226 close(config_s[0]); 1227 } 1228 break; 1229 } 1230 1231 /* 1232 * Normal production daemon. Fork, and have 1233 * the child process the connection. The 1234 * parent continues listening. 1235 */ 1236 platform_pre_fork(); 1237 if ((pid = fork()) == 0) { 1238 /* 1239 * Child. Close the listening and 1240 * max_startup sockets. Start using 1241 * the accepted socket. Reinitialize 1242 * logging (since our pid has changed). 1243 * We break out of the loop to handle 1244 * the connection. 1245 */ 1246 platform_post_fork_child(); 1247 startup_pipe = startup_p[1]; 1248 close_startup_pipes(); 1249 close_listen_socks(); 1250 *sock_in = *newsock; 1251 *sock_out = *newsock; 1252 log_init(__progname, 1253 options.log_level, 1254 options.log_facility, 1255 log_stderr); 1256 if (rexec_flag) 1257 close(config_s[0]); 1258 break; 1259 } 1260 1261 /* Parent. Stay in the loop. */ 1262 platform_post_fork_parent(pid); 1263 if (pid < 0) 1264 error("fork: %.100s", strerror(errno)); 1265 else 1266 debug("Forked child %ld.", (long)pid); 1267 1268 close(startup_p[1]); 1269 1270 if (rexec_flag) { 1271 send_rexec_state(config_s[0], &cfg); 1272 close(config_s[0]); 1273 close(config_s[1]); 1274 } 1275 1276 /* 1277 * Mark that the key has been used (it 1278 * was "given" to the child). 1279 */ 1280 if ((options.protocol & SSH_PROTO_1) && 1281 key_used == 0) { 1282 /* Schedule server key regeneration alarm. */ 1283 signal(SIGALRM, key_regeneration_alarm); 1284 alarm(options.key_regeneration_time); 1285 key_used = 1; 1286 } 1287 1288 close(*newsock); 1289 1290 /* 1291 * Ensure that our random state differs 1292 * from that of the child 1293 */ 1294 arc4random_stir(); 1295 } 1296 1297 /* child process check (or debug mode) */ 1298 if (num_listen_socks < 0) 1299 break; 1300 } 1301 } 1302 1303 1304 /* 1305 * Main program for the daemon. 1306 */ 1307 int 1308 main(int ac, char **av) 1309 { 1310 extern char *optarg; 1311 extern int optind; 1312 int opt, i, j, on = 1; 1313 int sock_in = -1, sock_out = -1, newsock = -1; 1314 const char *remote_ip; 1315 char *test_user = NULL, *test_host = NULL, *test_addr = NULL; 1316 int remote_port; 1317 char *line, *p, *cp; 1318 int config_s[2] = { -1 , -1 }; 1319 u_int64_t ibytes, obytes; 1320 mode_t new_umask; 1321 Key *key; 1322 Authctxt *authctxt; 1323 1324 #ifdef HAVE_SECUREWARE 1325 (void)set_auth_parameters(ac, av); 1326 #endif 1327 __progname = ssh_get_progname(av[0]); 1328 init_rng(); 1329 1330 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1331 saved_argc = ac; 1332 rexec_argc = ac; 1333 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1334 for (i = 0; i < ac; i++) 1335 saved_argv[i] = xstrdup(av[i]); 1336 saved_argv[i] = NULL; 1337 1338 #ifndef HAVE_SETPROCTITLE 1339 /* Prepare for later setproctitle emulation */ 1340 compat_init_setproctitle(ac, av); 1341 av = saved_argv; 1342 #endif 1343 1344 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1345 debug("setgroups(): %.200s", strerror(errno)); 1346 1347 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1348 sanitise_stdfd(); 1349 1350 /* Initialize configuration options to their default values. */ 1351 initialize_server_options(&options); 1352 1353 /* Parse command-line arguments. */ 1354 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) { 1355 switch (opt) { 1356 case '4': 1357 options.address_family = AF_INET; 1358 break; 1359 case '6': 1360 options.address_family = AF_INET6; 1361 break; 1362 case 'f': 1363 config_file_name = optarg; 1364 break; 1365 case 'c': 1366 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1367 fprintf(stderr, "too many host certificates.\n"); 1368 exit(1); 1369 } 1370 options.host_cert_files[options.num_host_cert_files++] = 1371 derelativise_path(optarg); 1372 break; 1373 case 'd': 1374 if (debug_flag == 0) { 1375 debug_flag = 1; 1376 options.log_level = SYSLOG_LEVEL_DEBUG1; 1377 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1378 options.log_level++; 1379 break; 1380 case 'D': 1381 no_daemon_flag = 1; 1382 break; 1383 case 'e': 1384 log_stderr = 1; 1385 break; 1386 case 'i': 1387 inetd_flag = 1; 1388 break; 1389 case 'r': 1390 rexec_flag = 0; 1391 break; 1392 case 'R': 1393 rexeced_flag = 1; 1394 inetd_flag = 1; 1395 break; 1396 case 'Q': 1397 /* ignored */ 1398 break; 1399 case 'q': 1400 options.log_level = SYSLOG_LEVEL_QUIET; 1401 break; 1402 case 'b': 1403 options.server_key_bits = (int)strtonum(optarg, 256, 1404 32768, NULL); 1405 break; 1406 case 'p': 1407 options.ports_from_cmdline = 1; 1408 if (options.num_ports >= MAX_PORTS) { 1409 fprintf(stderr, "too many ports.\n"); 1410 exit(1); 1411 } 1412 options.ports[options.num_ports++] = a2port(optarg); 1413 if (options.ports[options.num_ports-1] <= 0) { 1414 fprintf(stderr, "Bad port number.\n"); 1415 exit(1); 1416 } 1417 break; 1418 case 'g': 1419 if ((options.login_grace_time = convtime(optarg)) == -1) { 1420 fprintf(stderr, "Invalid login grace time.\n"); 1421 exit(1); 1422 } 1423 break; 1424 case 'k': 1425 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1426 fprintf(stderr, "Invalid key regeneration interval.\n"); 1427 exit(1); 1428 } 1429 break; 1430 case 'h': 1431 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1432 fprintf(stderr, "too many host keys.\n"); 1433 exit(1); 1434 } 1435 options.host_key_files[options.num_host_key_files++] = 1436 derelativise_path(optarg); 1437 break; 1438 case 't': 1439 test_flag = 1; 1440 break; 1441 case 'T': 1442 test_flag = 2; 1443 break; 1444 case 'C': 1445 cp = optarg; 1446 while ((p = strsep(&cp, ",")) && *p != '\0') { 1447 if (strncmp(p, "addr=", 5) == 0) 1448 test_addr = xstrdup(p + 5); 1449 else if (strncmp(p, "host=", 5) == 0) 1450 test_host = xstrdup(p + 5); 1451 else if (strncmp(p, "user=", 5) == 0) 1452 test_user = xstrdup(p + 5); 1453 else { 1454 fprintf(stderr, "Invalid test " 1455 "mode specification %s\n", p); 1456 exit(1); 1457 } 1458 } 1459 break; 1460 case 'u': 1461 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1462 if (utmp_len > MAXHOSTNAMELEN) { 1463 fprintf(stderr, "Invalid utmp length.\n"); 1464 exit(1); 1465 } 1466 break; 1467 case 'o': 1468 line = xstrdup(optarg); 1469 if (process_server_config_line(&options, line, 1470 "command-line", 0, NULL, NULL, NULL, NULL) != 0) 1471 exit(1); 1472 xfree(line); 1473 break; 1474 case '?': 1475 default: 1476 usage(); 1477 break; 1478 } 1479 } 1480 if (rexeced_flag || inetd_flag) 1481 rexec_flag = 0; 1482 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1483 fatal("sshd re-exec requires execution with an absolute path"); 1484 if (rexeced_flag) 1485 closefrom(REEXEC_MIN_FREE_FD); 1486 else 1487 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1488 1489 OpenSSL_add_all_algorithms(); 1490 1491 /* 1492 * Force logging to stderr until we have loaded the private host 1493 * key (unless started from inetd) 1494 */ 1495 log_init(__progname, 1496 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1497 SYSLOG_LEVEL_INFO : options.log_level, 1498 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1499 SYSLOG_FACILITY_AUTH : options.log_facility, 1500 log_stderr || !inetd_flag); 1501 1502 /* 1503 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1504 * root's environment 1505 */ 1506 if (getenv("KRB5CCNAME") != NULL) 1507 unsetenv("KRB5CCNAME"); 1508 1509 #ifdef _UNICOS 1510 /* Cray can define user privs drop all privs now! 1511 * Not needed on PRIV_SU systems! 1512 */ 1513 drop_cray_privs(); 1514 #endif 1515 1516 sensitive_data.server_key = NULL; 1517 sensitive_data.ssh1_host_key = NULL; 1518 sensitive_data.have_ssh1_key = 0; 1519 sensitive_data.have_ssh2_key = 0; 1520 1521 /* 1522 * If we're doing an extended config test, make sure we have all of 1523 * the parameters we need. If we're not doing an extended test, 1524 * do not silently ignore connection test params. 1525 */ 1526 if (test_flag >= 2 && 1527 (test_user != NULL || test_host != NULL || test_addr != NULL) 1528 && (test_user == NULL || test_host == NULL || test_addr == NULL)) 1529 fatal("user, host and addr are all required when testing " 1530 "Match configs"); 1531 if (test_flag < 2 && (test_user != NULL || test_host != NULL || 1532 test_addr != NULL)) 1533 fatal("Config test connection parameter (-C) provided without " 1534 "test mode (-T)"); 1535 1536 /* Fetch our configuration */ 1537 buffer_init(&cfg); 1538 if (rexeced_flag) 1539 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1540 else 1541 load_server_config(config_file_name, &cfg); 1542 1543 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1544 &cfg, NULL, NULL, NULL); 1545 1546 seed_rng(); 1547 1548 /* Fill in default values for those options not explicitly set. */ 1549 fill_default_server_options(&options); 1550 1551 /* challenge-response is implemented via keyboard interactive */ 1552 if (options.challenge_response_authentication) 1553 options.kbd_interactive_authentication = 1; 1554 1555 /* set default channel AF */ 1556 channel_set_af(options.address_family); 1557 1558 /* Check that there are no remaining arguments. */ 1559 if (optind < ac) { 1560 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1561 exit(1); 1562 } 1563 1564 debug("sshd version %.100s", SSH_RELEASE); 1565 1566 /* Store privilege separation user for later use if required. */ 1567 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1568 if (use_privsep || options.kerberos_authentication) 1569 fatal("Privilege separation user %s does not exist", 1570 SSH_PRIVSEP_USER); 1571 } else { 1572 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd)); 1573 privsep_pw = pwcopy(privsep_pw); 1574 xfree(privsep_pw->pw_passwd); 1575 privsep_pw->pw_passwd = xstrdup("*"); 1576 } 1577 endpwent(); 1578 1579 /* load private host keys */ 1580 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1581 sizeof(Key *)); 1582 for (i = 0; i < options.num_host_key_files; i++) 1583 sensitive_data.host_keys[i] = NULL; 1584 1585 for (i = 0; i < options.num_host_key_files; i++) { 1586 key = key_load_private(options.host_key_files[i], "", NULL); 1587 sensitive_data.host_keys[i] = key; 1588 if (key == NULL) { 1589 error("Could not load host key: %s", 1590 options.host_key_files[i]); 1591 sensitive_data.host_keys[i] = NULL; 1592 continue; 1593 } 1594 switch (key->type) { 1595 case KEY_RSA1: 1596 sensitive_data.ssh1_host_key = key; 1597 sensitive_data.have_ssh1_key = 1; 1598 break; 1599 case KEY_RSA: 1600 case KEY_DSA: 1601 case KEY_ECDSA: 1602 sensitive_data.have_ssh2_key = 1; 1603 break; 1604 } 1605 debug("private host key: #%d type %d %s", i, key->type, 1606 key_type(key)); 1607 } 1608 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1609 logit("Disabling protocol version 1. Could not load host key"); 1610 options.protocol &= ~SSH_PROTO_1; 1611 } 1612 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1613 logit("Disabling protocol version 2. Could not load host key"); 1614 options.protocol &= ~SSH_PROTO_2; 1615 } 1616 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1617 logit("sshd: no hostkeys available -- exiting."); 1618 exit(1); 1619 } 1620 1621 /* 1622 * Load certificates. They are stored in an array at identical 1623 * indices to the public keys that they relate to. 1624 */ 1625 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1626 sizeof(Key *)); 1627 for (i = 0; i < options.num_host_key_files; i++) 1628 sensitive_data.host_certificates[i] = NULL; 1629 1630 for (i = 0; i < options.num_host_cert_files; i++) { 1631 key = key_load_public(options.host_cert_files[i], NULL); 1632 if (key == NULL) { 1633 error("Could not load host certificate: %s", 1634 options.host_cert_files[i]); 1635 continue; 1636 } 1637 if (!key_is_cert(key)) { 1638 error("Certificate file is not a certificate: %s", 1639 options.host_cert_files[i]); 1640 key_free(key); 1641 continue; 1642 } 1643 /* Find matching private key */ 1644 for (j = 0; j < options.num_host_key_files; j++) { 1645 if (key_equal_public(key, 1646 sensitive_data.host_keys[j])) { 1647 sensitive_data.host_certificates[j] = key; 1648 break; 1649 } 1650 } 1651 if (j >= options.num_host_key_files) { 1652 error("No matching private key for certificate: %s", 1653 options.host_cert_files[i]); 1654 key_free(key); 1655 continue; 1656 } 1657 sensitive_data.host_certificates[j] = key; 1658 debug("host certificate: #%d type %d %s", j, key->type, 1659 key_type(key)); 1660 } 1661 /* Check certain values for sanity. */ 1662 if (options.protocol & SSH_PROTO_1) { 1663 if (options.server_key_bits < 512 || 1664 options.server_key_bits > 32768) { 1665 fprintf(stderr, "Bad server key size.\n"); 1666 exit(1); 1667 } 1668 /* 1669 * Check that server and host key lengths differ sufficiently. This 1670 * is necessary to make double encryption work with rsaref. Oh, I 1671 * hate software patents. I dont know if this can go? Niels 1672 */ 1673 if (options.server_key_bits > 1674 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1675 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1676 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1677 SSH_KEY_BITS_RESERVED) { 1678 options.server_key_bits = 1679 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1680 SSH_KEY_BITS_RESERVED; 1681 debug("Forcing server key to %d bits to make it differ from host key.", 1682 options.server_key_bits); 1683 } 1684 } 1685 1686 if (use_privsep) { 1687 struct stat st; 1688 1689 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1690 (S_ISDIR(st.st_mode) == 0)) 1691 fatal("Missing privilege separation directory: %s", 1692 _PATH_PRIVSEP_CHROOT_DIR); 1693 1694 #ifdef HAVE_CYGWIN 1695 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1696 (st.st_uid != getuid () || 1697 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1698 #else 1699 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1700 #endif 1701 fatal("%s must be owned by root and not group or " 1702 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1703 } 1704 1705 if (test_flag > 1) { 1706 if (test_user != NULL && test_addr != NULL && test_host != NULL) 1707 parse_server_match_config(&options, test_user, 1708 test_host, test_addr); 1709 dump_config(&options); 1710 } 1711 1712 /* Configuration looks good, so exit if in test mode. */ 1713 if (test_flag) 1714 exit(0); 1715 1716 /* 1717 * Clear out any supplemental groups we may have inherited. This 1718 * prevents inadvertent creation of files with bad modes (in the 1719 * portable version at least, it's certainly possible for PAM 1720 * to create a file, and we can't control the code in every 1721 * module which might be used). 1722 */ 1723 if (setgroups(0, NULL) < 0) 1724 debug("setgroups() failed: %.200s", strerror(errno)); 1725 1726 if (rexec_flag) { 1727 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1728 for (i = 0; i < rexec_argc; i++) { 1729 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1730 rexec_argv[i] = saved_argv[i]; 1731 } 1732 rexec_argv[rexec_argc] = "-R"; 1733 rexec_argv[rexec_argc + 1] = NULL; 1734 } 1735 1736 /* Ensure that umask disallows at least group and world write */ 1737 new_umask = umask(0077) | 0022; 1738 (void) umask(new_umask); 1739 1740 /* Initialize the log (it is reinitialized below in case we forked). */ 1741 if (debug_flag && (!inetd_flag || rexeced_flag)) 1742 log_stderr = 1; 1743 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1744 1745 /* 1746 * If not in debugging mode, and not started from inetd, disconnect 1747 * from the controlling terminal, and fork. The original process 1748 * exits. 1749 */ 1750 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1751 #ifdef TIOCNOTTY 1752 int fd; 1753 #endif /* TIOCNOTTY */ 1754 if (daemon(0, 0) < 0) 1755 fatal("daemon() failed: %.200s", strerror(errno)); 1756 1757 /* Disconnect from the controlling tty. */ 1758 #ifdef TIOCNOTTY 1759 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1760 if (fd >= 0) { 1761 (void) ioctl(fd, TIOCNOTTY, NULL); 1762 close(fd); 1763 } 1764 #endif /* TIOCNOTTY */ 1765 } 1766 /* Reinitialize the log (because of the fork above). */ 1767 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1768 1769 /* Avoid killing the process in high-pressure swapping environments. */ 1770 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 1771 debug("madvise(): %.200s", strerror(errno)); 1772 1773 /* Initialize the random number generator. */ 1774 arc4random_stir(); 1775 1776 /* Chdir to the root directory so that the current disk can be 1777 unmounted if desired. */ 1778 chdir("/"); 1779 1780 /* ignore SIGPIPE */ 1781 signal(SIGPIPE, SIG_IGN); 1782 1783 /* Get a connection, either from inetd or a listening TCP socket */ 1784 if (inetd_flag) { 1785 server_accept_inetd(&sock_in, &sock_out); 1786 } else { 1787 platform_pre_listen(); 1788 server_listen(); 1789 1790 if (options.protocol & SSH_PROTO_1) 1791 generate_ephemeral_server_key(); 1792 1793 signal(SIGHUP, sighup_handler); 1794 signal(SIGCHLD, main_sigchld_handler); 1795 signal(SIGTERM, sigterm_handler); 1796 signal(SIGQUIT, sigterm_handler); 1797 1798 /* 1799 * Write out the pid file after the sigterm handler 1800 * is setup and the listen sockets are bound 1801 */ 1802 if (!debug_flag) { 1803 FILE *f = fopen(options.pid_file, "w"); 1804 1805 if (f == NULL) { 1806 error("Couldn't create pid file \"%s\": %s", 1807 options.pid_file, strerror(errno)); 1808 } else { 1809 fprintf(f, "%ld\n", (long) getpid()); 1810 fclose(f); 1811 } 1812 } 1813 1814 /* Accept a connection and return in a forked child */ 1815 server_accept_loop(&sock_in, &sock_out, 1816 &newsock, config_s); 1817 } 1818 1819 /* This is the child processing a new connection. */ 1820 setproctitle("%s", "[accepted]"); 1821 1822 /* 1823 * Create a new session and process group since the 4.4BSD 1824 * setlogin() affects the entire process group. We don't 1825 * want the child to be able to affect the parent. 1826 */ 1827 #if !defined(SSHD_ACQUIRES_CTTY) 1828 /* 1829 * If setsid is called, on some platforms sshd will later acquire a 1830 * controlling terminal which will result in "could not set 1831 * controlling tty" errors. 1832 */ 1833 if (!debug_flag && !inetd_flag && setsid() < 0) 1834 error("setsid: %.100s", strerror(errno)); 1835 #endif 1836 1837 if (rexec_flag) { 1838 int fd; 1839 1840 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1841 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1842 dup2(newsock, STDIN_FILENO); 1843 dup2(STDIN_FILENO, STDOUT_FILENO); 1844 if (startup_pipe == -1) 1845 close(REEXEC_STARTUP_PIPE_FD); 1846 else 1847 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1848 1849 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1850 close(config_s[1]); 1851 if (startup_pipe != -1) 1852 close(startup_pipe); 1853 1854 execv(rexec_argv[0], rexec_argv); 1855 1856 /* Reexec has failed, fall back and continue */ 1857 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1858 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1859 log_init(__progname, options.log_level, 1860 options.log_facility, log_stderr); 1861 1862 /* Clean up fds */ 1863 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1864 close(config_s[1]); 1865 close(REEXEC_CONFIG_PASS_FD); 1866 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1867 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1868 dup2(fd, STDIN_FILENO); 1869 dup2(fd, STDOUT_FILENO); 1870 if (fd > STDERR_FILENO) 1871 close(fd); 1872 } 1873 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1874 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1875 } 1876 1877 /* Executed child processes don't need these. */ 1878 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1879 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1880 1881 /* 1882 * Disable the key regeneration alarm. We will not regenerate the 1883 * key since we are no longer in a position to give it to anyone. We 1884 * will not restart on SIGHUP since it no longer makes sense. 1885 */ 1886 alarm(0); 1887 signal(SIGALRM, SIG_DFL); 1888 signal(SIGHUP, SIG_DFL); 1889 signal(SIGTERM, SIG_DFL); 1890 signal(SIGQUIT, SIG_DFL); 1891 signal(SIGCHLD, SIG_DFL); 1892 signal(SIGINT, SIG_DFL); 1893 1894 #ifdef __FreeBSD__ 1895 /* 1896 * Initialize the resolver. This may not happen automatically 1897 * before privsep chroot(). 1898 */ 1899 if ((_res.options & RES_INIT) == 0) { 1900 debug("res_init()"); 1901 res_init(); 1902 } 1903 #ifdef GSSAPI 1904 /* 1905 * Force GSS-API to parse its configuration and load any 1906 * mechanism plugins. 1907 */ 1908 { 1909 gss_OID_set mechs; 1910 OM_uint32 minor_status; 1911 gss_indicate_mechs(&minor_status, &mechs); 1912 gss_release_oid_set(&minor_status, &mechs); 1913 } 1914 #endif 1915 #endif 1916 1917 /* 1918 * Register our connection. This turns encryption off because we do 1919 * not have a key. 1920 */ 1921 packet_set_connection(sock_in, sock_out); 1922 packet_set_server(); 1923 1924 /* Set SO_KEEPALIVE if requested. */ 1925 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1926 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1927 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1928 1929 if ((remote_port = get_remote_port()) < 0) { 1930 debug("get_remote_port failed"); 1931 cleanup_exit(255); 1932 } 1933 1934 /* 1935 * We use get_canonical_hostname with usedns = 0 instead of 1936 * get_remote_ipaddr here so IP options will be checked. 1937 */ 1938 (void) get_canonical_hostname(0); 1939 /* 1940 * The rest of the code depends on the fact that 1941 * get_remote_ipaddr() caches the remote ip, even if 1942 * the socket goes away. 1943 */ 1944 remote_ip = get_remote_ipaddr(); 1945 1946 #ifdef SSH_AUDIT_EVENTS 1947 audit_connection_from(remote_ip, remote_port); 1948 #endif 1949 #ifdef LIBWRAP 1950 allow_severity = options.log_facility|LOG_INFO; 1951 deny_severity = options.log_facility|LOG_WARNING; 1952 /* Check whether logins are denied from this host. */ 1953 if (packet_connection_is_on_socket()) { 1954 struct request_info req; 1955 1956 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 1957 fromhost(&req); 1958 1959 if (!hosts_access(&req)) { 1960 debug("Connection refused by tcp wrapper"); 1961 refuse(&req); 1962 /* NOTREACHED */ 1963 fatal("libwrap refuse returns"); 1964 } 1965 } 1966 #endif /* LIBWRAP */ 1967 1968 /* Log the connection. */ 1969 verbose("Connection from %.500s port %d", remote_ip, remote_port); 1970 1971 /* Set HPN options for the child. */ 1972 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size); 1973 1974 /* 1975 * We don't want to listen forever unless the other side 1976 * successfully authenticates itself. So we set up an alarm which is 1977 * cleared after successful authentication. A limit of zero 1978 * indicates no limit. Note that we don't set the alarm in debugging 1979 * mode; it is just annoying to have the server exit just when you 1980 * are about to discover the bug. 1981 */ 1982 signal(SIGALRM, grace_alarm_handler); 1983 if (!debug_flag) 1984 alarm(options.login_grace_time); 1985 1986 sshd_exchange_identification(sock_in, sock_out); 1987 1988 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 1989 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 1990 generate_ephemeral_server_key(); 1991 1992 packet_set_nonblocking(); 1993 1994 /* allocate authentication context */ 1995 authctxt = xcalloc(1, sizeof(*authctxt)); 1996 1997 authctxt->loginmsg = &loginmsg; 1998 1999 /* XXX global for cleanup, access from other modules */ 2000 the_authctxt = authctxt; 2001 2002 /* prepare buffer to collect messages to display to user after login */ 2003 buffer_init(&loginmsg); 2004 auth_debug_reset(); 2005 2006 if (use_privsep) 2007 if (privsep_preauth(authctxt) == 1) 2008 goto authenticated; 2009 2010 /* perform the key exchange */ 2011 /* authenticate user and start session */ 2012 if (compat20) { 2013 do_ssh2_kex(); 2014 do_authentication2(authctxt); 2015 } else { 2016 do_ssh1_kex(); 2017 do_authentication(authctxt); 2018 } 2019 /* 2020 * If we use privilege separation, the unprivileged child transfers 2021 * the current keystate and exits 2022 */ 2023 if (use_privsep) { 2024 mm_send_keystate(pmonitor); 2025 exit(0); 2026 } 2027 2028 authenticated: 2029 /* 2030 * Cancel the alarm we set to limit the time taken for 2031 * authentication. 2032 */ 2033 alarm(0); 2034 signal(SIGALRM, SIG_DFL); 2035 authctxt->authenticated = 1; 2036 if (startup_pipe != -1) { 2037 close(startup_pipe); 2038 startup_pipe = -1; 2039 } 2040 2041 #ifdef SSH_AUDIT_EVENTS 2042 audit_event(SSH_AUTH_SUCCESS); 2043 #endif 2044 2045 #ifdef GSSAPI 2046 if (options.gss_authentication) { 2047 temporarily_use_uid(authctxt->pw); 2048 ssh_gssapi_storecreds(); 2049 restore_uid(); 2050 } 2051 #endif 2052 #ifdef USE_PAM 2053 if (options.use_pam) { 2054 do_pam_setcred(1); 2055 do_pam_session(); 2056 } 2057 #endif 2058 2059 /* 2060 * In privilege separation, we fork another child and prepare 2061 * file descriptor passing. 2062 */ 2063 if (use_privsep) { 2064 privsep_postauth(authctxt); 2065 /* the monitor process [priv] will not return */ 2066 if (!compat20) 2067 destroy_sensitive_data(); 2068 } 2069 2070 packet_set_timeout(options.client_alive_interval, 2071 options.client_alive_count_max); 2072 2073 /* Start session. */ 2074 do_authenticated(authctxt); 2075 2076 /* The connection has been terminated. */ 2077 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 2078 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 2079 verbose("Transferred: sent %llu, received %llu bytes", 2080 (unsigned long long)obytes, (unsigned long long)ibytes); 2081 2082 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2083 2084 #ifdef USE_PAM 2085 if (options.use_pam) 2086 finish_pam(); 2087 #endif /* USE_PAM */ 2088 2089 #ifdef SSH_AUDIT_EVENTS 2090 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2091 #endif 2092 2093 packet_close(); 2094 2095 if (use_privsep) 2096 mm_terminate(); 2097 2098 exit(0); 2099 } 2100 2101 /* 2102 * Decrypt session_key_int using our private server key and private host key 2103 * (key with larger modulus first). 2104 */ 2105 int 2106 ssh1_session_key(BIGNUM *session_key_int) 2107 { 2108 int rsafail = 0; 2109 2110 if (BN_cmp(sensitive_data.server_key->rsa->n, 2111 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2112 /* Server key has bigger modulus. */ 2113 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2114 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2115 SSH_KEY_BITS_RESERVED) { 2116 fatal("do_connection: %s: " 2117 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2118 get_remote_ipaddr(), 2119 BN_num_bits(sensitive_data.server_key->rsa->n), 2120 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2121 SSH_KEY_BITS_RESERVED); 2122 } 2123 if (rsa_private_decrypt(session_key_int, session_key_int, 2124 sensitive_data.server_key->rsa) <= 0) 2125 rsafail++; 2126 if (rsa_private_decrypt(session_key_int, session_key_int, 2127 sensitive_data.ssh1_host_key->rsa) <= 0) 2128 rsafail++; 2129 } else { 2130 /* Host key has bigger modulus (or they are equal). */ 2131 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2132 BN_num_bits(sensitive_data.server_key->rsa->n) + 2133 SSH_KEY_BITS_RESERVED) { 2134 fatal("do_connection: %s: " 2135 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2136 get_remote_ipaddr(), 2137 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2138 BN_num_bits(sensitive_data.server_key->rsa->n), 2139 SSH_KEY_BITS_RESERVED); 2140 } 2141 if (rsa_private_decrypt(session_key_int, session_key_int, 2142 sensitive_data.ssh1_host_key->rsa) < 0) 2143 rsafail++; 2144 if (rsa_private_decrypt(session_key_int, session_key_int, 2145 sensitive_data.server_key->rsa) < 0) 2146 rsafail++; 2147 } 2148 return (rsafail); 2149 } 2150 /* 2151 * SSH1 key exchange 2152 */ 2153 static void 2154 do_ssh1_kex(void) 2155 { 2156 int i, len; 2157 int rsafail = 0; 2158 BIGNUM *session_key_int; 2159 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2160 u_char cookie[8]; 2161 u_int cipher_type, auth_mask, protocol_flags; 2162 2163 /* 2164 * Generate check bytes that the client must send back in the user 2165 * packet in order for it to be accepted; this is used to defy ip 2166 * spoofing attacks. Note that this only works against somebody 2167 * doing IP spoofing from a remote machine; any machine on the local 2168 * network can still see outgoing packets and catch the random 2169 * cookie. This only affects rhosts authentication, and this is one 2170 * of the reasons why it is inherently insecure. 2171 */ 2172 arc4random_buf(cookie, sizeof(cookie)); 2173 2174 /* 2175 * Send our public key. We include in the packet 64 bits of random 2176 * data that must be matched in the reply in order to prevent IP 2177 * spoofing. 2178 */ 2179 packet_start(SSH_SMSG_PUBLIC_KEY); 2180 for (i = 0; i < 8; i++) 2181 packet_put_char(cookie[i]); 2182 2183 /* Store our public server RSA key. */ 2184 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2185 packet_put_bignum(sensitive_data.server_key->rsa->e); 2186 packet_put_bignum(sensitive_data.server_key->rsa->n); 2187 2188 /* Store our public host RSA key. */ 2189 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2190 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2191 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2192 2193 /* Put protocol flags. */ 2194 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2195 2196 /* Declare which ciphers we support. */ 2197 packet_put_int(cipher_mask_ssh1(0)); 2198 2199 /* Declare supported authentication types. */ 2200 auth_mask = 0; 2201 if (options.rhosts_rsa_authentication) 2202 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2203 if (options.rsa_authentication) 2204 auth_mask |= 1 << SSH_AUTH_RSA; 2205 if (options.challenge_response_authentication == 1) 2206 auth_mask |= 1 << SSH_AUTH_TIS; 2207 if (options.password_authentication) 2208 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2209 packet_put_int(auth_mask); 2210 2211 /* Send the packet and wait for it to be sent. */ 2212 packet_send(); 2213 packet_write_wait(); 2214 2215 debug("Sent %d bit server key and %d bit host key.", 2216 BN_num_bits(sensitive_data.server_key->rsa->n), 2217 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2218 2219 /* Read clients reply (cipher type and session key). */ 2220 packet_read_expect(SSH_CMSG_SESSION_KEY); 2221 2222 /* Get cipher type and check whether we accept this. */ 2223 cipher_type = packet_get_char(); 2224 2225 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2226 packet_disconnect("Warning: client selects unsupported cipher."); 2227 2228 /* Get check bytes from the packet. These must match those we 2229 sent earlier with the public key packet. */ 2230 for (i = 0; i < 8; i++) 2231 if (cookie[i] != packet_get_char()) 2232 packet_disconnect("IP Spoofing check bytes do not match."); 2233 2234 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2235 2236 /* Get the encrypted integer. */ 2237 if ((session_key_int = BN_new()) == NULL) 2238 fatal("do_ssh1_kex: BN_new failed"); 2239 packet_get_bignum(session_key_int); 2240 2241 protocol_flags = packet_get_int(); 2242 packet_set_protocol_flags(protocol_flags); 2243 packet_check_eom(); 2244 2245 /* Decrypt session_key_int using host/server keys */ 2246 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2247 2248 /* 2249 * Extract session key from the decrypted integer. The key is in the 2250 * least significant 256 bits of the integer; the first byte of the 2251 * key is in the highest bits. 2252 */ 2253 if (!rsafail) { 2254 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2255 len = BN_num_bytes(session_key_int); 2256 if (len < 0 || (u_int)len > sizeof(session_key)) { 2257 error("do_ssh1_kex: bad session key len from %s: " 2258 "session_key_int %d > sizeof(session_key) %lu", 2259 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2260 rsafail++; 2261 } else { 2262 memset(session_key, 0, sizeof(session_key)); 2263 BN_bn2bin(session_key_int, 2264 session_key + sizeof(session_key) - len); 2265 2266 derive_ssh1_session_id( 2267 sensitive_data.ssh1_host_key->rsa->n, 2268 sensitive_data.server_key->rsa->n, 2269 cookie, session_id); 2270 /* 2271 * Xor the first 16 bytes of the session key with the 2272 * session id. 2273 */ 2274 for (i = 0; i < 16; i++) 2275 session_key[i] ^= session_id[i]; 2276 } 2277 } 2278 if (rsafail) { 2279 int bytes = BN_num_bytes(session_key_int); 2280 u_char *buf = xmalloc(bytes); 2281 MD5_CTX md; 2282 2283 logit("do_connection: generating a fake encryption key"); 2284 BN_bn2bin(session_key_int, buf); 2285 MD5_Init(&md); 2286 MD5_Update(&md, buf, bytes); 2287 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2288 MD5_Final(session_key, &md); 2289 MD5_Init(&md); 2290 MD5_Update(&md, session_key, 16); 2291 MD5_Update(&md, buf, bytes); 2292 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2293 MD5_Final(session_key + 16, &md); 2294 memset(buf, 0, bytes); 2295 xfree(buf); 2296 for (i = 0; i < 16; i++) 2297 session_id[i] = session_key[i] ^ session_key[i + 16]; 2298 } 2299 /* Destroy the private and public keys. No longer. */ 2300 destroy_sensitive_data(); 2301 2302 if (use_privsep) 2303 mm_ssh1_session_id(session_id); 2304 2305 /* Destroy the decrypted integer. It is no longer needed. */ 2306 BN_clear_free(session_key_int); 2307 2308 /* Set the session key. From this on all communications will be encrypted. */ 2309 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2310 2311 /* Destroy our copy of the session key. It is no longer needed. */ 2312 memset(session_key, 0, sizeof(session_key)); 2313 2314 debug("Received session key; encryption turned on."); 2315 2316 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2317 packet_start(SSH_SMSG_SUCCESS); 2318 packet_send(); 2319 packet_write_wait(); 2320 } 2321 2322 /* 2323 * SSH2 key exchange: diffie-hellman-group1-sha1 2324 */ 2325 static void 2326 do_ssh2_kex(void) 2327 { 2328 Kex *kex; 2329 2330 if (options.ciphers != NULL) { 2331 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2332 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2333 #ifdef NONE_CIPHER_ENABLED 2334 } else if (options.none_enabled == 1) { 2335 debug ("WARNING: None cipher enabled"); 2336 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2337 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE; 2338 #endif 2339 } 2340 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2341 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2342 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2343 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2344 2345 if (options.macs != NULL) { 2346 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2347 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2348 } 2349 if (options.compression == COMP_NONE) { 2350 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2351 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2352 } else if (options.compression == COMP_DELAYED) { 2353 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2354 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2355 } 2356 if (options.kex_algorithms != NULL) 2357 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 2358 2359 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); 2360 2361 /* start key exchange */ 2362 kex = kex_setup(myproposal); 2363 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2364 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2365 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2366 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2367 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2368 kex->server = 1; 2369 kex->client_version_string=client_version_string; 2370 kex->server_version_string=server_version_string; 2371 kex->load_host_public_key=&get_hostkey_public_by_type; 2372 kex->load_host_private_key=&get_hostkey_private_by_type; 2373 kex->host_key_index=&get_hostkey_index; 2374 2375 xxx_kex = kex; 2376 2377 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2378 2379 session_id2 = kex->session_id; 2380 session_id2_len = kex->session_id_len; 2381 2382 #ifdef DEBUG_KEXDH 2383 /* send 1st encrypted/maced/compressed message */ 2384 packet_start(SSH2_MSG_IGNORE); 2385 packet_put_cstring("markus"); 2386 packet_send(); 2387 packet_write_wait(); 2388 #endif 2389 debug("KEX done"); 2390 } 2391 2392 /* server specific fatal cleanup */ 2393 void 2394 cleanup_exit(int i) 2395 { 2396 if (the_authctxt) 2397 do_cleanup(the_authctxt); 2398 #ifdef SSH_AUDIT_EVENTS 2399 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2400 if (!use_privsep || mm_is_monitor()) 2401 audit_event(SSH_CONNECTION_ABANDON); 2402 #endif 2403 _exit(i); 2404 } 2405