1 /* $OpenBSD: sshd.c,v 1.385 2011/06/23 09:34:13 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This program is the ssh daemon. It listens for connections from clients, 7 * and performs authentication, executes use commands or shell, and forwards 8 * information to/from the application to the user client over an encrypted 9 * connection. This can also handle forwarding of X11, TCP/IP, and 10 * authentication agent connections. 11 * 12 * As far as I am concerned, the code I have written for this software 13 * can be used freely for any purpose. Any derived versions of this 14 * software must be clearly marked as such, and if the derived work is 15 * incompatible with the protocol description in the RFC file, it must be 16 * called by a name other than "ssh" or "Secure Shell". 17 * 18 * SSH2 implementation: 19 * Privilege Separation: 20 * 21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 22 * Copyright (c) 2002 Niels Provos. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 43 */ 44 45 #include "includes.h" 46 47 #include <sys/types.h> 48 #include <sys/ioctl.h> 49 #include <sys/socket.h> 50 #ifdef HAVE_SYS_STAT_H 51 # include <sys/stat.h> 52 #endif 53 #ifdef HAVE_SYS_TIME_H 54 # include <sys/time.h> 55 #endif 56 #include "openbsd-compat/sys-tree.h" 57 #include "openbsd-compat/sys-queue.h" 58 #include <sys/wait.h> 59 60 #include <errno.h> 61 #include <fcntl.h> 62 #include <netdb.h> 63 #ifdef HAVE_PATHS_H 64 #include <paths.h> 65 #endif 66 #include <grp.h> 67 #include <pwd.h> 68 #include <signal.h> 69 #include <stdarg.h> 70 #include <stdio.h> 71 #include <stdlib.h> 72 #include <string.h> 73 #include <unistd.h> 74 75 #include <openssl/dh.h> 76 #include <openssl/bn.h> 77 #include <openssl/md5.h> 78 #include <openssl/rand.h> 79 #include "openbsd-compat/openssl-compat.h" 80 81 #ifdef HAVE_SECUREWARE 82 #include <sys/security.h> 83 #include <prot.h> 84 #endif 85 86 #include <resolv.h> 87 #include "xmalloc.h" 88 #include "ssh.h" 89 #include "ssh1.h" 90 #include "ssh2.h" 91 #include "rsa.h" 92 #include "sshpty.h" 93 #include "packet.h" 94 #include "log.h" 95 #include "buffer.h" 96 #include "servconf.h" 97 #include "uidswap.h" 98 #include "compat.h" 99 #include "cipher.h" 100 #include "key.h" 101 #include "kex.h" 102 #include "dh.h" 103 #include "myproposal.h" 104 #include "authfile.h" 105 #include "pathnames.h" 106 #include "atomicio.h" 107 #include "canohost.h" 108 #include "hostfile.h" 109 #include "auth.h" 110 #include "misc.h" 111 #include "msg.h" 112 #include "dispatch.h" 113 #include "channels.h" 114 #include "session.h" 115 #include "monitor_mm.h" 116 #include "monitor.h" 117 #ifdef GSSAPI 118 #include "ssh-gss.h" 119 #endif 120 #include "monitor_wrap.h" 121 #include "roaming.h" 122 #include "ssh-sandbox.h" 123 #include "version.h" 124 125 #ifdef LIBWRAP 126 #include <tcpd.h> 127 #include <syslog.h> 128 int allow_severity; 129 int deny_severity; 130 #endif /* LIBWRAP */ 131 132 #ifndef O_NOCTTY 133 #define O_NOCTTY 0 134 #endif 135 136 /* Re-exec fds */ 137 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 138 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 139 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 140 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 141 142 int myflag = 0; 143 144 145 extern char *__progname; 146 147 /* Server configuration options. */ 148 ServerOptions options; 149 150 /* Name of the server configuration file. */ 151 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 152 153 /* 154 * Debug mode flag. This can be set on the command line. If debug 155 * mode is enabled, extra debugging output will be sent to the system 156 * log, the daemon will not go to background, and will exit after processing 157 * the first connection. 158 */ 159 int debug_flag = 0; 160 161 /* Flag indicating that the daemon should only test the configuration and keys. */ 162 int test_flag = 0; 163 164 /* Flag indicating that the daemon is being started from inetd. */ 165 int inetd_flag = 0; 166 167 /* Flag indicating that sshd should not detach and become a daemon. */ 168 int no_daemon_flag = 0; 169 170 /* debug goes to stderr unless inetd_flag is set */ 171 int log_stderr = 0; 172 173 /* Saved arguments to main(). */ 174 char **saved_argv; 175 int saved_argc; 176 177 /* re-exec */ 178 int rexeced_flag = 0; 179 int rexec_flag = 1; 180 int rexec_argc = 0; 181 char **rexec_argv; 182 183 /* 184 * The sockets that the server is listening; this is used in the SIGHUP 185 * signal handler. 186 */ 187 #define MAX_LISTEN_SOCKS 16 188 int listen_socks[MAX_LISTEN_SOCKS]; 189 int num_listen_socks = 0; 190 191 /* 192 * the client's version string, passed by sshd2 in compat mode. if != NULL, 193 * sshd will skip the version-number exchange 194 */ 195 char *client_version_string = NULL; 196 char *server_version_string = NULL; 197 198 /* for rekeying XXX fixme */ 199 Kex *xxx_kex; 200 201 /* 202 * Any really sensitive data in the application is contained in this 203 * structure. The idea is that this structure could be locked into memory so 204 * that the pages do not get written into swap. However, there are some 205 * problems. The private key contains BIGNUMs, and we do not (in principle) 206 * have access to the internals of them, and locking just the structure is 207 * not very useful. Currently, memory locking is not implemented. 208 */ 209 struct { 210 Key *server_key; /* ephemeral server key */ 211 Key *ssh1_host_key; /* ssh1 host key */ 212 Key **host_keys; /* all private host keys */ 213 Key **host_certificates; /* all public host certificates */ 214 int have_ssh1_key; 215 int have_ssh2_key; 216 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 217 } sensitive_data; 218 219 /* 220 * Flag indicating whether the RSA server key needs to be regenerated. 221 * Is set in the SIGALRM handler and cleared when the key is regenerated. 222 */ 223 static volatile sig_atomic_t key_do_regen = 0; 224 225 /* This is set to true when a signal is received. */ 226 static volatile sig_atomic_t received_sighup = 0; 227 static volatile sig_atomic_t received_sigterm = 0; 228 229 /* session identifier, used by RSA-auth */ 230 u_char session_id[16]; 231 232 /* same for ssh2 */ 233 u_char *session_id2 = NULL; 234 u_int session_id2_len = 0; 235 236 /* record remote hostname or ip */ 237 u_int utmp_len = MAXHOSTNAMELEN; 238 239 /* options.max_startup sized array of fd ints */ 240 int *startup_pipes = NULL; 241 int startup_pipe; /* in child */ 242 243 /* variables used for privilege separation */ 244 int use_privsep = -1; 245 struct monitor *pmonitor = NULL; 246 247 /* global authentication context */ 248 Authctxt *the_authctxt = NULL; 249 250 /* sshd_config buffer */ 251 Buffer cfg; 252 253 /* message to be displayed after login */ 254 Buffer loginmsg; 255 256 /* Unprivileged user */ 257 struct passwd *privsep_pw = NULL; 258 259 /* Prototypes for various functions defined later in this file. */ 260 void destroy_sensitive_data(void); 261 void demote_sensitive_data(void); 262 263 static void do_ssh1_kex(void); 264 static void do_ssh2_kex(void); 265 266 /* 267 * Close all listening sockets 268 */ 269 static void 270 close_listen_socks(void) 271 { 272 int i; 273 274 for (i = 0; i < num_listen_socks; i++) 275 close(listen_socks[i]); 276 num_listen_socks = -1; 277 } 278 279 static void 280 close_startup_pipes(void) 281 { 282 int i; 283 284 if (startup_pipes) 285 for (i = 0; i < options.max_startups; i++) 286 if (startup_pipes[i] != -1) 287 close(startup_pipes[i]); 288 } 289 290 /* 291 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 292 * the effect is to reread the configuration file (and to regenerate 293 * the server key). 294 */ 295 296 /*ARGSUSED*/ 297 static void 298 sighup_handler(int sig) 299 { 300 int save_errno = errno; 301 302 received_sighup = 1; 303 signal(SIGHUP, sighup_handler); 304 errno = save_errno; 305 } 306 307 /* 308 * Called from the main program after receiving SIGHUP. 309 * Restarts the server. 310 */ 311 static void 312 sighup_restart(void) 313 { 314 logit("Received SIGHUP; restarting."); 315 close_listen_socks(); 316 close_startup_pipes(); 317 alarm(0); /* alarm timer persists across exec */ 318 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 319 execv(saved_argv[0], saved_argv); 320 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 321 strerror(errno)); 322 exit(1); 323 } 324 325 /* 326 * Generic signal handler for terminating signals in the master daemon. 327 */ 328 /*ARGSUSED*/ 329 static void 330 sigterm_handler(int sig) 331 { 332 received_sigterm = sig; 333 } 334 335 /* 336 * SIGCHLD handler. This is called whenever a child dies. This will then 337 * reap any zombies left by exited children. 338 */ 339 /*ARGSUSED*/ 340 static void 341 main_sigchld_handler(int sig) 342 { 343 int save_errno = errno; 344 pid_t pid; 345 int status; 346 347 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 348 (pid < 0 && errno == EINTR)) 349 ; 350 351 signal(SIGCHLD, main_sigchld_handler); 352 errno = save_errno; 353 } 354 355 /* 356 * Signal handler for the alarm after the login grace period has expired. 357 */ 358 /*ARGSUSED*/ 359 static void 360 grace_alarm_handler(int sig) 361 { 362 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 363 kill(pmonitor->m_pid, SIGALRM); 364 365 /* Log error and exit. */ 366 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 367 } 368 369 /* 370 * Signal handler for the key regeneration alarm. Note that this 371 * alarm only occurs in the daemon waiting for connections, and it does not 372 * do anything with the private key or random state before forking. 373 * Thus there should be no concurrency control/asynchronous execution 374 * problems. 375 */ 376 static void 377 generate_ephemeral_server_key(void) 378 { 379 verbose("Generating %s%d bit RSA key.", 380 sensitive_data.server_key ? "new " : "", options.server_key_bits); 381 if (sensitive_data.server_key != NULL) 382 key_free(sensitive_data.server_key); 383 sensitive_data.server_key = key_generate(KEY_RSA1, 384 options.server_key_bits); 385 verbose("RSA key generation complete."); 386 387 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 388 arc4random_stir(); 389 } 390 391 /*ARGSUSED*/ 392 static void 393 key_regeneration_alarm(int sig) 394 { 395 int save_errno = errno; 396 397 signal(SIGALRM, SIG_DFL); 398 errno = save_errno; 399 key_do_regen = 1; 400 } 401 402 static void 403 sshd_exchange_identification(int sock_in, int sock_out) 404 { 405 u_int i; 406 int mismatch; 407 int remote_major, remote_minor; 408 int major, minor; 409 char *s, *newline = "\n"; 410 char buf[256]; /* Must not be larger than remote_version. */ 411 char remote_version[256]; /* Must be at least as big as buf. */ 412 413 if ((options.protocol & SSH_PROTO_1) && 414 (options.protocol & SSH_PROTO_2)) { 415 major = PROTOCOL_MAJOR_1; 416 minor = 99; 417 } else if (options.protocol & SSH_PROTO_2) { 418 major = PROTOCOL_MAJOR_2; 419 minor = PROTOCOL_MINOR_2; 420 newline = "\r\n"; 421 } else { 422 major = PROTOCOL_MAJOR_1; 423 minor = PROTOCOL_MINOR_1; 424 } 425 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor, 426 SSH_RELEASE, newline); 427 server_version_string = xstrdup(buf); 428 429 /* Send our protocol version identification. */ 430 if (roaming_atomicio(vwrite, sock_out, server_version_string, 431 strlen(server_version_string)) 432 != strlen(server_version_string)) { 433 logit("Could not write ident string to %s", get_remote_ipaddr()); 434 cleanup_exit(255); 435 } 436 437 /* Read other sides version identification. */ 438 memset(buf, 0, sizeof(buf)); 439 for (i = 0; i < sizeof(buf) - 1; i++) { 440 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 441 logit("Did not receive identification string from %s", 442 get_remote_ipaddr()); 443 cleanup_exit(255); 444 } 445 if (buf[i] == '\r') { 446 buf[i] = 0; 447 /* Kludge for F-Secure Macintosh < 1.0.2 */ 448 if (i == 12 && 449 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 450 break; 451 continue; 452 } 453 if (buf[i] == '\n') { 454 buf[i] = 0; 455 break; 456 } 457 } 458 buf[sizeof(buf) - 1] = 0; 459 client_version_string = xstrdup(buf); 460 461 /* 462 * Check that the versions match. In future this might accept 463 * several versions and set appropriate flags to handle them. 464 */ 465 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 466 &remote_major, &remote_minor, remote_version) != 3) { 467 s = "Protocol mismatch.\n"; 468 (void) atomicio(vwrite, sock_out, s, strlen(s)); 469 close(sock_in); 470 close(sock_out); 471 logit("Bad protocol version identification '%.100s' from %s", 472 client_version_string, get_remote_ipaddr()); 473 cleanup_exit(255); 474 } 475 debug("Client protocol version %d.%d; client software version %.100s", 476 remote_major, remote_minor, remote_version); 477 logit("SSH: Server;Ltype: Version;Remote: %s-%d;Protocol: %d.%d;Client: %.100s", 478 get_remote_ipaddr(), get_remote_port(), 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 if (sensitive_data.host_certificates[i]) { 558 key_free(sensitive_data.host_certificates[i]); 559 sensitive_data.host_certificates[i] = NULL; 560 } 561 } 562 sensitive_data.ssh1_host_key = NULL; 563 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); 564 } 565 566 /* Demote private to public keys for network child */ 567 void 568 demote_sensitive_data(void) 569 { 570 Key *tmp; 571 int i; 572 573 if (sensitive_data.server_key) { 574 tmp = key_demote(sensitive_data.server_key); 575 key_free(sensitive_data.server_key); 576 sensitive_data.server_key = tmp; 577 } 578 579 for (i = 0; i < options.num_host_key_files; i++) { 580 if (sensitive_data.host_keys[i]) { 581 tmp = key_demote(sensitive_data.host_keys[i]); 582 key_free(sensitive_data.host_keys[i]); 583 sensitive_data.host_keys[i] = tmp; 584 if (tmp->type == KEY_RSA1) 585 sensitive_data.ssh1_host_key = tmp; 586 } 587 /* Certs do not need demotion */ 588 } 589 590 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 591 } 592 593 static void 594 privsep_preauth_child(void) 595 { 596 u_int32_t rnd[256]; 597 gid_t gidset[1]; 598 599 /* Enable challenge-response authentication for privilege separation */ 600 privsep_challenge_enable(); 601 602 arc4random_stir(); 603 arc4random_buf(rnd, sizeof(rnd)); 604 RAND_seed(rnd, sizeof(rnd)); 605 606 /* Demote the private keys to public keys. */ 607 demote_sensitive_data(); 608 609 /* Change our root directory */ 610 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 611 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 612 strerror(errno)); 613 if (chdir("/") == -1) 614 fatal("chdir(\"/\"): %s", strerror(errno)); 615 616 /* Drop our privileges */ 617 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 618 (u_int)privsep_pw->pw_gid); 619 #if 0 620 /* XXX not ready, too heavy after chroot */ 621 do_setusercontext(privsep_pw); 622 #else 623 gidset[0] = privsep_pw->pw_gid; 624 if (setgroups(1, gidset) < 0) 625 fatal("setgroups: %.100s", strerror(errno)); 626 permanently_set_uid(privsep_pw); 627 #endif 628 } 629 630 static int 631 privsep_preauth(Authctxt *authctxt) 632 { 633 int status; 634 pid_t pid; 635 struct ssh_sandbox *box = NULL; 636 637 /* Set up unprivileged child process to deal with network data */ 638 pmonitor = monitor_init(); 639 /* Store a pointer to the kex for later rekeying */ 640 pmonitor->m_pkex = &xxx_kex; 641 642 if (use_privsep == PRIVSEP_SANDBOX) 643 box = ssh_sandbox_init(); 644 pid = fork(); 645 if (pid == -1) { 646 fatal("fork of unprivileged child failed"); 647 } else if (pid != 0) { 648 debug2("Network child is on pid %ld", (long)pid); 649 650 if (box != NULL) 651 ssh_sandbox_parent_preauth(box, pid); 652 pmonitor->m_pid = pid; 653 monitor_child_preauth(authctxt, pmonitor); 654 655 /* Sync memory */ 656 monitor_sync(pmonitor); 657 658 /* Wait for the child's exit status */ 659 while (waitpid(pid, &status, 0) < 0) { 660 if (errno != EINTR) 661 fatal("%s: waitpid: %s", __func__, 662 strerror(errno)); 663 } 664 if (WIFEXITED(status)) { 665 if (WEXITSTATUS(status) != 0) 666 fatal("%s: preauth child exited with status %d", 667 __func__, WEXITSTATUS(status)); 668 } else if (WIFSIGNALED(status)) 669 fatal("%s: preauth child terminated by signal %d", 670 __func__, WTERMSIG(status)); 671 if (box != NULL) 672 ssh_sandbox_parent_finish(box); 673 return 1; 674 } else { 675 /* child */ 676 close(pmonitor->m_sendfd); 677 close(pmonitor->m_log_recvfd); 678 679 /* Arrange for logging to be sent to the monitor */ 680 set_log_handler(mm_log_handler, pmonitor); 681 682 /* Demote the child */ 683 if (getuid() == 0 || geteuid() == 0) 684 privsep_preauth_child(); 685 setproctitle("%s", "[net]"); 686 if (box != NULL) 687 ssh_sandbox_child(box); 688 689 return 0; 690 } 691 } 692 693 static void 694 privsep_postauth(Authctxt *authctxt) 695 { 696 u_int32_t rnd[256]; 697 698 #ifdef DISABLE_FD_PASSING 699 if (1) { 700 #else 701 if (authctxt->pw->pw_uid == 0 || options.use_login) { 702 #endif 703 /* File descriptor passing is broken or root login */ 704 use_privsep = 0; 705 goto skip; 706 } 707 708 /* New socket pair */ 709 monitor_reinit(pmonitor); 710 711 pmonitor->m_pid = fork(); 712 if (pmonitor->m_pid == -1) 713 fatal("fork of unprivileged child failed"); 714 else if (pmonitor->m_pid != 0) { 715 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 716 buffer_clear(&loginmsg); 717 monitor_child_postauth(pmonitor); 718 719 /* NEVERREACHED */ 720 exit(0); 721 } 722 723 /* child */ 724 725 close(pmonitor->m_sendfd); 726 pmonitor->m_sendfd = -1; 727 728 /* Demote the private keys to public keys. */ 729 demote_sensitive_data(); 730 731 arc4random_stir(); 732 arc4random_buf(rnd, sizeof(rnd)); 733 RAND_seed(rnd, sizeof(rnd)); 734 735 /* Drop privileges */ 736 do_setusercontext(authctxt->pw); 737 738 skip: 739 /* It is safe now to apply the key state */ 740 monitor_apply_keystate(pmonitor); 741 742 /* 743 * Tell the packet layer that authentication was successful, since 744 * this information is not part of the key state. 745 */ 746 packet_set_authenticated(); 747 } 748 749 static char * 750 list_hostkey_types(void) 751 { 752 Buffer b; 753 const char *p; 754 char *ret; 755 int i; 756 Key *key; 757 758 buffer_init(&b); 759 for (i = 0; i < options.num_host_key_files; i++) { 760 key = sensitive_data.host_keys[i]; 761 if (key == NULL) 762 continue; 763 switch (key->type) { 764 case KEY_RSA: 765 case KEY_DSA: 766 case KEY_ECDSA: 767 if (buffer_len(&b) > 0) 768 buffer_append(&b, ",", 1); 769 p = key_ssh_name(key); 770 buffer_append(&b, p, strlen(p)); 771 break; 772 } 773 /* If the private key has a cert peer, then list that too */ 774 key = sensitive_data.host_certificates[i]; 775 if (key == NULL) 776 continue; 777 switch (key->type) { 778 case KEY_RSA_CERT_V00: 779 case KEY_DSA_CERT_V00: 780 case KEY_RSA_CERT: 781 case KEY_DSA_CERT: 782 case KEY_ECDSA_CERT: 783 if (buffer_len(&b) > 0) 784 buffer_append(&b, ",", 1); 785 p = key_ssh_name(key); 786 buffer_append(&b, p, strlen(p)); 787 break; 788 } 789 } 790 buffer_append(&b, "\0", 1); 791 ret = xstrdup(buffer_ptr(&b)); 792 buffer_free(&b); 793 debug("list_hostkey_types: %s", ret); 794 return ret; 795 } 796 797 static Key * 798 get_hostkey_by_type(int type, int need_private) 799 { 800 int i; 801 Key *key; 802 803 for (i = 0; i < options.num_host_key_files; i++) { 804 switch (type) { 805 case KEY_RSA_CERT_V00: 806 case KEY_DSA_CERT_V00: 807 case KEY_RSA_CERT: 808 case KEY_DSA_CERT: 809 case KEY_ECDSA_CERT: 810 key = sensitive_data.host_certificates[i]; 811 break; 812 default: 813 key = sensitive_data.host_keys[i]; 814 break; 815 } 816 if (key != NULL && key->type == type) 817 return need_private ? 818 sensitive_data.host_keys[i] : key; 819 } 820 return NULL; 821 } 822 823 Key * 824 get_hostkey_public_by_type(int type) 825 { 826 return get_hostkey_by_type(type, 0); 827 } 828 829 Key * 830 get_hostkey_private_by_type(int type) 831 { 832 return get_hostkey_by_type(type, 1); 833 } 834 835 Key * 836 get_hostkey_by_index(int ind) 837 { 838 if (ind < 0 || ind >= options.num_host_key_files) 839 return (NULL); 840 return (sensitive_data.host_keys[ind]); 841 } 842 843 int 844 get_hostkey_index(Key *key) 845 { 846 int i; 847 848 for (i = 0; i < options.num_host_key_files; i++) { 849 if (key_is_cert(key)) { 850 if (key == sensitive_data.host_certificates[i]) 851 return (i); 852 } else { 853 if (key == sensitive_data.host_keys[i]) 854 return (i); 855 } 856 } 857 return (-1); 858 } 859 860 /* 861 * returns 1 if connection should be dropped, 0 otherwise. 862 * dropping starts at connection #max_startups_begin with a probability 863 * of (max_startups_rate/100). the probability increases linearly until 864 * all connections are dropped for startups > max_startups 865 */ 866 static int 867 drop_connection(int startups) 868 { 869 int p, r; 870 871 if (startups < options.max_startups_begin) 872 return 0; 873 if (startups >= options.max_startups) 874 return 1; 875 if (options.max_startups_rate == 100) 876 return 1; 877 878 p = 100 - options.max_startups_rate; 879 p *= startups - options.max_startups_begin; 880 p /= options.max_startups - options.max_startups_begin; 881 p += options.max_startups_rate; 882 r = arc4random_uniform(100); 883 884 debug("drop_connection: p %d, r %d", p, r); 885 return (r < p) ? 1 : 0; 886 } 887 888 static void 889 usage(void) 890 { 891 fprintf(stderr, "%s, %s\n", 892 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); 893 fprintf(stderr, 894 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 895 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n" 896 " [-k key_gen_time] [-o option] [-p port] [-u len]\n" 897 ); 898 exit(1); 899 } 900 901 static void 902 send_rexec_state(int fd, Buffer *conf) 903 { 904 Buffer m; 905 906 debug3("%s: entering fd = %d config len %d", __func__, fd, 907 buffer_len(conf)); 908 909 /* 910 * Protocol from reexec master to child: 911 * string configuration 912 * u_int ephemeral_key_follows 913 * bignum e (only if ephemeral_key_follows == 1) 914 * bignum n " 915 * bignum d " 916 * bignum iqmp " 917 * bignum p " 918 * bignum q " 919 * string rngseed (only if OpenSSL is not self-seeded) 920 */ 921 buffer_init(&m); 922 buffer_put_cstring(&m, buffer_ptr(conf)); 923 924 if (sensitive_data.server_key != NULL && 925 sensitive_data.server_key->type == KEY_RSA1) { 926 buffer_put_int(&m, 1); 927 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 928 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 929 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 930 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 931 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 932 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 933 } else 934 buffer_put_int(&m, 0); 935 936 #ifndef OPENSSL_PRNG_ONLY 937 rexec_send_rng_seed(&m); 938 #endif 939 940 if (ssh_msg_send(fd, 0, &m) == -1) 941 fatal("%s: ssh_msg_send failed", __func__); 942 943 buffer_free(&m); 944 945 debug3("%s: done", __func__); 946 } 947 948 static void 949 recv_rexec_state(int fd, Buffer *conf) 950 { 951 Buffer m; 952 char *cp; 953 u_int len; 954 955 debug3("%s: entering fd = %d", __func__, fd); 956 957 buffer_init(&m); 958 959 if (ssh_msg_recv(fd, &m) == -1) 960 fatal("%s: ssh_msg_recv failed", __func__); 961 if (buffer_get_char(&m) != 0) 962 fatal("%s: rexec version mismatch", __func__); 963 964 cp = buffer_get_string(&m, &len); 965 if (conf != NULL) 966 buffer_append(conf, cp, len + 1); 967 xfree(cp); 968 969 if (buffer_get_int(&m)) { 970 if (sensitive_data.server_key != NULL) 971 key_free(sensitive_data.server_key); 972 sensitive_data.server_key = key_new_private(KEY_RSA1); 973 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 974 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 975 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 976 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 977 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 978 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 979 rsa_generate_additional_parameters( 980 sensitive_data.server_key->rsa); 981 } 982 983 #ifndef OPENSSL_PRNG_ONLY 984 rexec_recv_rng_seed(&m); 985 #endif 986 987 buffer_free(&m); 988 989 debug3("%s: done", __func__); 990 } 991 992 /* Accept a connection from inetd */ 993 static void 994 server_accept_inetd(int *sock_in, int *sock_out) 995 { 996 int fd; 997 998 startup_pipe = -1; 999 if (rexeced_flag) { 1000 close(REEXEC_CONFIG_PASS_FD); 1001 *sock_in = *sock_out = dup(STDIN_FILENO); 1002 if (!debug_flag) { 1003 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1004 close(REEXEC_STARTUP_PIPE_FD); 1005 } 1006 } else { 1007 *sock_in = dup(STDIN_FILENO); 1008 *sock_out = dup(STDOUT_FILENO); 1009 } 1010 /* 1011 * We intentionally do not close the descriptors 0, 1, and 2 1012 * as our code for setting the descriptors won't work if 1013 * ttyfd happens to be one of those. 1014 */ 1015 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1016 dup2(fd, STDIN_FILENO); 1017 dup2(fd, STDOUT_FILENO); 1018 if (fd > STDOUT_FILENO) 1019 close(fd); 1020 } 1021 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1022 } 1023 1024 /* 1025 * Listen for TCP connections 1026 */ 1027 static void 1028 server_listen(void) 1029 { 1030 int ret, listen_sock, on = 1; 1031 struct addrinfo *ai; 1032 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1033 int socksize; 1034 int socksizelen = sizeof(int); 1035 1036 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1037 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1038 continue; 1039 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1040 fatal("Too many listen sockets. " 1041 "Enlarge MAX_LISTEN_SOCKS"); 1042 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1043 ntop, sizeof(ntop), strport, sizeof(strport), 1044 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1045 error("getnameinfo failed: %.100s", 1046 ssh_gai_strerror(ret)); 1047 continue; 1048 } 1049 /* Create socket for listening. */ 1050 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1051 ai->ai_protocol); 1052 if (listen_sock < 0) { 1053 /* kernel may not support ipv6 */ 1054 verbose("socket: %.100s", strerror(errno)); 1055 continue; 1056 } 1057 if (set_nonblock(listen_sock) == -1) { 1058 close(listen_sock); 1059 continue; 1060 } 1061 /* 1062 * Set socket options. 1063 * Allow local port reuse in TIME_WAIT. 1064 */ 1065 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1066 &on, sizeof(on)) == -1) 1067 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1068 1069 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1070 if (ai->ai_family == AF_INET6) 1071 sock_set_v6only(listen_sock); 1072 1073 debug("Bind to port %s on %s.", strport, ntop); 1074 1075 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, 1076 &socksize, &socksizelen); 1077 debug("Server TCP RWIN socket size: %d", socksize); 1078 debug("HPN Buffer Size: %d", options.hpn_buffer_size); 1079 1080 /* Bind the socket to the desired port. */ 1081 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1082 error("Bind to port %s on %s failed: %.200s.", 1083 strport, ntop, strerror(errno)); 1084 close(listen_sock); 1085 continue; 1086 } 1087 listen_socks[num_listen_socks] = listen_sock; 1088 num_listen_socks++; 1089 1090 /* Start listening on the port. */ 1091 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1092 fatal("listen on [%s]:%s: %.100s", 1093 ntop, strport, strerror(errno)); 1094 logit("Server listening on %s port %s.", ntop, strport); 1095 } 1096 freeaddrinfo(options.listen_addrs); 1097 1098 if (!num_listen_socks) 1099 fatal("Cannot bind any address."); 1100 } 1101 1102 /* 1103 * The main TCP accept loop. Note that, for the non-debug case, returns 1104 * from this function are in a forked subprocess. 1105 */ 1106 static void 1107 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1108 { 1109 fd_set *fdset; 1110 int i, j, ret, maxfd; 1111 int key_used = 0, startups = 0; 1112 int startup_p[2] = { -1 , -1 }; 1113 struct sockaddr_storage from; 1114 socklen_t fromlen; 1115 pid_t pid; 1116 1117 /* setup fd set for accept */ 1118 fdset = NULL; 1119 maxfd = 0; 1120 for (i = 0; i < num_listen_socks; i++) 1121 if (listen_socks[i] > maxfd) 1122 maxfd = listen_socks[i]; 1123 /* pipes connected to unauthenticated childs */ 1124 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1125 for (i = 0; i < options.max_startups; i++) 1126 startup_pipes[i] = -1; 1127 1128 /* 1129 * Stay listening for connections until the system crashes or 1130 * the daemon is killed with a signal. 1131 */ 1132 for (;;) { 1133 if (received_sighup) 1134 sighup_restart(); 1135 if (fdset != NULL) 1136 xfree(fdset); 1137 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1138 sizeof(fd_mask)); 1139 1140 for (i = 0; i < num_listen_socks; i++) 1141 FD_SET(listen_socks[i], fdset); 1142 for (i = 0; i < options.max_startups; i++) 1143 if (startup_pipes[i] != -1) 1144 FD_SET(startup_pipes[i], fdset); 1145 1146 /* Wait in select until there is a connection. */ 1147 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1148 if (ret < 0 && errno != EINTR) 1149 error("select: %.100s", strerror(errno)); 1150 if (received_sigterm) { 1151 logit("Received signal %d; terminating.", 1152 (int) received_sigterm); 1153 close_listen_socks(); 1154 unlink(options.pid_file); 1155 exit(received_sigterm == SIGTERM ? 0 : 255); 1156 } 1157 if (key_used && key_do_regen) { 1158 generate_ephemeral_server_key(); 1159 key_used = 0; 1160 key_do_regen = 0; 1161 } 1162 if (ret < 0) 1163 continue; 1164 1165 for (i = 0; i < options.max_startups; i++) 1166 if (startup_pipes[i] != -1 && 1167 FD_ISSET(startup_pipes[i], fdset)) { 1168 /* 1169 * the read end of the pipe is ready 1170 * if the child has closed the pipe 1171 * after successful authentication 1172 * or if the child has died 1173 */ 1174 close(startup_pipes[i]); 1175 startup_pipes[i] = -1; 1176 startups--; 1177 } 1178 for (i = 0; i < num_listen_socks; i++) { 1179 if (!FD_ISSET(listen_socks[i], fdset)) 1180 continue; 1181 fromlen = sizeof(from); 1182 *newsock = accept(listen_socks[i], 1183 (struct sockaddr *)&from, &fromlen); 1184 if (*newsock < 0) { 1185 if (errno != EINTR && errno != EAGAIN && 1186 errno != EWOULDBLOCK) 1187 error("accept: %.100s", strerror(errno)); 1188 continue; 1189 } 1190 if (unset_nonblock(*newsock) == -1) { 1191 close(*newsock); 1192 continue; 1193 } 1194 if (drop_connection(startups) == 1) { 1195 debug("drop connection #%d", startups); 1196 close(*newsock); 1197 continue; 1198 } 1199 if (pipe(startup_p) == -1) { 1200 close(*newsock); 1201 continue; 1202 } 1203 1204 if (rexec_flag && socketpair(AF_UNIX, 1205 SOCK_STREAM, 0, config_s) == -1) { 1206 error("reexec socketpair: %s", 1207 strerror(errno)); 1208 close(*newsock); 1209 close(startup_p[0]); 1210 close(startup_p[1]); 1211 continue; 1212 } 1213 1214 for (j = 0; j < options.max_startups; j++) 1215 if (startup_pipes[j] == -1) { 1216 startup_pipes[j] = startup_p[0]; 1217 if (maxfd < startup_p[0]) 1218 maxfd = startup_p[0]; 1219 startups++; 1220 break; 1221 } 1222 1223 /* 1224 * Got connection. Fork a child to handle it, unless 1225 * we are in debugging mode. 1226 */ 1227 if (debug_flag) { 1228 /* 1229 * In debugging mode. Close the listening 1230 * socket, and start processing the 1231 * connection without forking. 1232 */ 1233 debug("Server will not fork when running in debugging mode."); 1234 close_listen_socks(); 1235 *sock_in = *newsock; 1236 *sock_out = *newsock; 1237 close(startup_p[0]); 1238 close(startup_p[1]); 1239 startup_pipe = -1; 1240 pid = getpid(); 1241 if (rexec_flag) { 1242 send_rexec_state(config_s[0], 1243 &cfg); 1244 close(config_s[0]); 1245 } 1246 break; 1247 } 1248 1249 /* 1250 * Normal production daemon. Fork, and have 1251 * the child process the connection. The 1252 * parent continues listening. 1253 */ 1254 platform_pre_fork(); 1255 if ((pid = fork()) == 0) { 1256 /* 1257 * Child. Close the listening and 1258 * max_startup sockets. Start using 1259 * the accepted socket. Reinitialize 1260 * logging (since our pid has changed). 1261 * We break out of the loop to handle 1262 * the connection. 1263 */ 1264 platform_post_fork_child(); 1265 startup_pipe = startup_p[1]; 1266 close_startup_pipes(); 1267 close_listen_socks(); 1268 *sock_in = *newsock; 1269 *sock_out = *newsock; 1270 log_init(__progname, 1271 options.log_level, 1272 options.log_facility, 1273 log_stderr); 1274 if (rexec_flag) 1275 close(config_s[0]); 1276 break; 1277 } 1278 1279 /* Parent. Stay in the loop. */ 1280 platform_post_fork_parent(pid); 1281 if (pid < 0) 1282 error("fork: %.100s", strerror(errno)); 1283 else 1284 debug("Forked child %ld.", (long)pid); 1285 1286 close(startup_p[1]); 1287 1288 if (rexec_flag) { 1289 send_rexec_state(config_s[0], &cfg); 1290 close(config_s[0]); 1291 close(config_s[1]); 1292 } 1293 1294 /* 1295 * Mark that the key has been used (it 1296 * was "given" to the child). 1297 */ 1298 if ((options.protocol & SSH_PROTO_1) && 1299 key_used == 0) { 1300 /* Schedule server key regeneration alarm. */ 1301 signal(SIGALRM, key_regeneration_alarm); 1302 alarm(options.key_regeneration_time); 1303 key_used = 1; 1304 } 1305 1306 close(*newsock); 1307 1308 /* 1309 * Ensure that our random state differs 1310 * from that of the child 1311 */ 1312 arc4random_stir(); 1313 } 1314 1315 /* child process check (or debug mode) */ 1316 if (num_listen_socks < 0) 1317 break; 1318 } 1319 } 1320 1321 1322 /* 1323 * Main program for the daemon. 1324 */ 1325 int 1326 main(int ac, char **av) 1327 { 1328 extern char *optarg; 1329 extern int optind; 1330 int opt, i, j, on = 1; 1331 int sock_in = -1, sock_out = -1, newsock = -1; 1332 const char *remote_ip; 1333 char *test_user = NULL, *test_host = NULL, *test_addr = NULL; 1334 int remote_port; 1335 char *line, *p, *cp; 1336 int config_s[2] = { -1 , -1 }; 1337 u_int64_t ibytes, obytes; 1338 mode_t new_umask; 1339 Key *key; 1340 Authctxt *authctxt; 1341 1342 #ifdef HAVE_SECUREWARE 1343 (void)set_auth_parameters(ac, av); 1344 #endif 1345 __progname = ssh_get_progname(av[0]); 1346 1347 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1348 saved_argc = ac; 1349 rexec_argc = ac; 1350 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1351 for (i = 0; i < ac; i++) 1352 saved_argv[i] = xstrdup(av[i]); 1353 saved_argv[i] = NULL; 1354 1355 #ifndef HAVE_SETPROCTITLE 1356 /* Prepare for later setproctitle emulation */ 1357 compat_init_setproctitle(ac, av); 1358 av = saved_argv; 1359 #endif 1360 1361 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1362 debug("setgroups(): %.200s", strerror(errno)); 1363 1364 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1365 sanitise_stdfd(); 1366 1367 /* Initialize configuration options to their default values. */ 1368 initialize_server_options(&options); 1369 1370 /* Parse command-line arguments. */ 1371 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) { 1372 switch (opt) { 1373 case '4': 1374 options.address_family = AF_INET; 1375 break; 1376 case '6': 1377 options.address_family = AF_INET6; 1378 break; 1379 case 'f': 1380 config_file_name = optarg; 1381 break; 1382 case 'c': 1383 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1384 fprintf(stderr, "too many host certificates.\n"); 1385 exit(1); 1386 } 1387 options.host_cert_files[options.num_host_cert_files++] = 1388 derelativise_path(optarg); 1389 break; 1390 case 'd': 1391 if (debug_flag == 0) { 1392 debug_flag = 1; 1393 options.log_level = SYSLOG_LEVEL_DEBUG1; 1394 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1395 options.log_level++; 1396 break; 1397 case 'D': 1398 no_daemon_flag = 1; 1399 break; 1400 case 'e': 1401 log_stderr = 1; 1402 break; 1403 case 'i': 1404 inetd_flag = 1; 1405 break; 1406 case 'r': 1407 rexec_flag = 0; 1408 break; 1409 case 'R': 1410 rexeced_flag = 1; 1411 inetd_flag = 1; 1412 break; 1413 case 'Q': 1414 /* ignored */ 1415 break; 1416 case 'q': 1417 options.log_level = SYSLOG_LEVEL_QUIET; 1418 break; 1419 case 'b': 1420 options.server_key_bits = (int)strtonum(optarg, 256, 1421 32768, NULL); 1422 break; 1423 case 'p': 1424 options.ports_from_cmdline = 1; 1425 if (options.num_ports >= MAX_PORTS) { 1426 fprintf(stderr, "too many ports.\n"); 1427 exit(1); 1428 } 1429 options.ports[options.num_ports++] = a2port(optarg); 1430 if (options.ports[options.num_ports-1] <= 0) { 1431 fprintf(stderr, "Bad port number.\n"); 1432 exit(1); 1433 } 1434 break; 1435 case 'g': 1436 if ((options.login_grace_time = convtime(optarg)) == -1) { 1437 fprintf(stderr, "Invalid login grace time.\n"); 1438 exit(1); 1439 } 1440 break; 1441 case 'k': 1442 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1443 fprintf(stderr, "Invalid key regeneration interval.\n"); 1444 exit(1); 1445 } 1446 break; 1447 case 'h': 1448 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1449 fprintf(stderr, "too many host keys.\n"); 1450 exit(1); 1451 } 1452 options.host_key_files[options.num_host_key_files++] = 1453 derelativise_path(optarg); 1454 break; 1455 case 't': 1456 test_flag = 1; 1457 break; 1458 case 'T': 1459 test_flag = 2; 1460 break; 1461 case 'C': 1462 cp = optarg; 1463 while ((p = strsep(&cp, ",")) && *p != '\0') { 1464 if (strncmp(p, "addr=", 5) == 0) 1465 test_addr = xstrdup(p + 5); 1466 else if (strncmp(p, "host=", 5) == 0) 1467 test_host = xstrdup(p + 5); 1468 else if (strncmp(p, "user=", 5) == 0) 1469 test_user = xstrdup(p + 5); 1470 else { 1471 fprintf(stderr, "Invalid test " 1472 "mode specification %s\n", p); 1473 exit(1); 1474 } 1475 } 1476 break; 1477 case 'u': 1478 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1479 if (utmp_len > MAXHOSTNAMELEN) { 1480 fprintf(stderr, "Invalid utmp length.\n"); 1481 exit(1); 1482 } 1483 break; 1484 case 'o': 1485 line = xstrdup(optarg); 1486 if (process_server_config_line(&options, line, 1487 "command-line", 0, NULL, NULL, NULL, NULL) != 0) 1488 exit(1); 1489 xfree(line); 1490 break; 1491 case '?': 1492 default: 1493 usage(); 1494 break; 1495 } 1496 } 1497 if (rexeced_flag || inetd_flag) 1498 rexec_flag = 0; 1499 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1500 fatal("sshd re-exec requires execution with an absolute path"); 1501 if (rexeced_flag) 1502 closefrom(REEXEC_MIN_FREE_FD); 1503 else 1504 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1505 1506 OpenSSL_add_all_algorithms(); 1507 1508 /* 1509 * Force logging to stderr until we have loaded the private host 1510 * key (unless started from inetd) 1511 */ 1512 log_init(__progname, 1513 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1514 SYSLOG_LEVEL_INFO : options.log_level, 1515 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1516 SYSLOG_FACILITY_AUTH : options.log_facility, 1517 log_stderr || !inetd_flag); 1518 1519 /* 1520 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1521 * root's environment 1522 */ 1523 if (getenv("KRB5CCNAME") != NULL) 1524 unsetenv("KRB5CCNAME"); 1525 1526 #ifdef _UNICOS 1527 /* Cray can define user privs drop all privs now! 1528 * Not needed on PRIV_SU systems! 1529 */ 1530 drop_cray_privs(); 1531 #endif 1532 1533 sensitive_data.server_key = NULL; 1534 sensitive_data.ssh1_host_key = NULL; 1535 sensitive_data.have_ssh1_key = 0; 1536 sensitive_data.have_ssh2_key = 0; 1537 1538 /* 1539 * If we're doing an extended config test, make sure we have all of 1540 * the parameters we need. If we're not doing an extended test, 1541 * do not silently ignore connection test params. 1542 */ 1543 if (test_flag >= 2 && 1544 (test_user != NULL || test_host != NULL || test_addr != NULL) 1545 && (test_user == NULL || test_host == NULL || test_addr == NULL)) 1546 fatal("user, host and addr are all required when testing " 1547 "Match configs"); 1548 if (test_flag < 2 && (test_user != NULL || test_host != NULL || 1549 test_addr != NULL)) 1550 fatal("Config test connection parameter (-C) provided without " 1551 "test mode (-T)"); 1552 1553 /* Fetch our configuration */ 1554 buffer_init(&cfg); 1555 if (rexeced_flag) 1556 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1557 else 1558 load_server_config(config_file_name, &cfg); 1559 1560 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1561 &cfg, NULL, NULL, NULL); 1562 1563 seed_rng(); 1564 1565 /* Fill in default values for those options not explicitly set. */ 1566 fill_default_server_options(&options); 1567 1568 /* challenge-response is implemented via keyboard interactive */ 1569 if (options.challenge_response_authentication) 1570 options.kbd_interactive_authentication = 1; 1571 1572 /* set default channel AF */ 1573 channel_set_af(options.address_family); 1574 1575 /* Check that there are no remaining arguments. */ 1576 if (optind < ac) { 1577 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1578 exit(1); 1579 } 1580 1581 debug("sshd version %.100s", SSH_RELEASE); 1582 1583 /* Store privilege separation user for later use if required. */ 1584 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1585 if (use_privsep || options.kerberos_authentication) 1586 fatal("Privilege separation user %s does not exist", 1587 SSH_PRIVSEP_USER); 1588 } else { 1589 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd)); 1590 privsep_pw = pwcopy(privsep_pw); 1591 xfree(privsep_pw->pw_passwd); 1592 privsep_pw->pw_passwd = xstrdup("*"); 1593 } 1594 endpwent(); 1595 1596 /* load private host keys */ 1597 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1598 sizeof(Key *)); 1599 for (i = 0; i < options.num_host_key_files; i++) 1600 sensitive_data.host_keys[i] = NULL; 1601 1602 for (i = 0; i < options.num_host_key_files; i++) { 1603 key = key_load_private(options.host_key_files[i], "", NULL); 1604 if (key && blacklisted_key(key)) { 1605 char *fp; 1606 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 1607 if (options.permit_blacklisted_keys) 1608 error("Host key %s blacklisted (see " 1609 "ssh-vulnkey(1)); continuing anyway", fp); 1610 else 1611 error("Host key %s blacklisted (see " 1612 "ssh-vulnkey(1))", fp); 1613 xfree(fp); 1614 if (!options.permit_blacklisted_keys) { 1615 sensitive_data.host_keys[i] = NULL; 1616 continue; 1617 } 1618 } 1619 sensitive_data.host_keys[i] = key; 1620 if (key == NULL) { 1621 error("Could not load host key: %s", 1622 options.host_key_files[i]); 1623 sensitive_data.host_keys[i] = NULL; 1624 continue; 1625 } 1626 switch (key->type) { 1627 case KEY_RSA1: 1628 sensitive_data.ssh1_host_key = key; 1629 sensitive_data.have_ssh1_key = 1; 1630 break; 1631 case KEY_RSA: 1632 case KEY_DSA: 1633 case KEY_ECDSA: 1634 sensitive_data.have_ssh2_key = 1; 1635 break; 1636 } 1637 debug("private host key: #%d type %d %s", i, key->type, 1638 key_type(key)); 1639 } 1640 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1641 logit("Disabling protocol version 1. Could not load host key"); 1642 options.protocol &= ~SSH_PROTO_1; 1643 } 1644 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1645 logit("Disabling protocol version 2. Could not load host key"); 1646 options.protocol &= ~SSH_PROTO_2; 1647 } 1648 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1649 logit("sshd: no hostkeys available -- exiting."); 1650 exit(1); 1651 } 1652 1653 /* 1654 * Load certificates. They are stored in an array at identical 1655 * indices to the public keys that they relate to. 1656 */ 1657 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1658 sizeof(Key *)); 1659 for (i = 0; i < options.num_host_key_files; i++) 1660 sensitive_data.host_certificates[i] = NULL; 1661 1662 for (i = 0; i < options.num_host_cert_files; i++) { 1663 key = key_load_public(options.host_cert_files[i], NULL); 1664 if (key == NULL) { 1665 error("Could not load host certificate: %s", 1666 options.host_cert_files[i]); 1667 continue; 1668 } 1669 if (!key_is_cert(key)) { 1670 error("Certificate file is not a certificate: %s", 1671 options.host_cert_files[i]); 1672 key_free(key); 1673 continue; 1674 } 1675 /* Find matching private key */ 1676 for (j = 0; j < options.num_host_key_files; j++) { 1677 if (key_equal_public(key, 1678 sensitive_data.host_keys[j])) { 1679 sensitive_data.host_certificates[j] = key; 1680 break; 1681 } 1682 } 1683 if (j >= options.num_host_key_files) { 1684 error("No matching private key for certificate: %s", 1685 options.host_cert_files[i]); 1686 key_free(key); 1687 continue; 1688 } 1689 sensitive_data.host_certificates[j] = key; 1690 debug("host certificate: #%d type %d %s", j, key->type, 1691 key_type(key)); 1692 } 1693 /* Check certain values for sanity. */ 1694 if (options.protocol & SSH_PROTO_1) { 1695 if (options.server_key_bits < 512 || 1696 options.server_key_bits > 32768) { 1697 fprintf(stderr, "Bad server key size.\n"); 1698 exit(1); 1699 } 1700 /* 1701 * Check that server and host key lengths differ sufficiently. This 1702 * is necessary to make double encryption work with rsaref. Oh, I 1703 * hate software patents. I dont know if this can go? Niels 1704 */ 1705 if (options.server_key_bits > 1706 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1707 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1708 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1709 SSH_KEY_BITS_RESERVED) { 1710 options.server_key_bits = 1711 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1712 SSH_KEY_BITS_RESERVED; 1713 debug("Forcing server key to %d bits to make it differ from host key.", 1714 options.server_key_bits); 1715 } 1716 } 1717 1718 if (use_privsep) { 1719 struct stat st; 1720 1721 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1722 (S_ISDIR(st.st_mode) == 0)) 1723 fatal("Missing privilege separation directory: %s", 1724 _PATH_PRIVSEP_CHROOT_DIR); 1725 1726 #ifdef HAVE_CYGWIN 1727 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1728 (st.st_uid != getuid () || 1729 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1730 #else 1731 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1732 #endif 1733 fatal("%s must be owned by root and not group or " 1734 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1735 } 1736 1737 if (test_flag > 1) { 1738 if (test_user != NULL && test_addr != NULL && test_host != NULL) 1739 parse_server_match_config(&options, test_user, 1740 test_host, test_addr); 1741 dump_config(&options); 1742 } 1743 1744 /* Configuration looks good, so exit if in test mode. */ 1745 if (test_flag) 1746 exit(0); 1747 1748 /* 1749 * Clear out any supplemental groups we may have inherited. This 1750 * prevents inadvertent creation of files with bad modes (in the 1751 * portable version at least, it's certainly possible for PAM 1752 * to create a file, and we can't control the code in every 1753 * module which might be used). 1754 */ 1755 if (setgroups(0, NULL) < 0) 1756 debug("setgroups() failed: %.200s", strerror(errno)); 1757 1758 if (rexec_flag) { 1759 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1760 for (i = 0; i < rexec_argc; i++) { 1761 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1762 rexec_argv[i] = saved_argv[i]; 1763 } 1764 rexec_argv[rexec_argc] = "-R"; 1765 rexec_argv[rexec_argc + 1] = NULL; 1766 } 1767 1768 /* Ensure that umask disallows at least group and world write */ 1769 new_umask = umask(0077) | 0022; 1770 (void) umask(new_umask); 1771 1772 /* Initialize the log (it is reinitialized below in case we forked). */ 1773 if (debug_flag && (!inetd_flag || rexeced_flag)) 1774 log_stderr = 1; 1775 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1776 1777 /* 1778 * If not in debugging mode, and not started from inetd, disconnect 1779 * from the controlling terminal, and fork. The original process 1780 * exits. 1781 */ 1782 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1783 #ifdef TIOCNOTTY 1784 int fd; 1785 #endif /* TIOCNOTTY */ 1786 if (daemon(0, 0) < 0) 1787 fatal("daemon() failed: %.200s", strerror(errno)); 1788 1789 /* Disconnect from the controlling tty. */ 1790 #ifdef TIOCNOTTY 1791 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1792 if (fd >= 0) { 1793 (void) ioctl(fd, TIOCNOTTY, NULL); 1794 close(fd); 1795 } 1796 #endif /* TIOCNOTTY */ 1797 } 1798 /* Reinitialize the log (because of the fork above). */ 1799 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1800 1801 /* Initialize the random number generator. */ 1802 arc4random_stir(); 1803 1804 /* Chdir to the root directory so that the current disk can be 1805 unmounted if desired. */ 1806 chdir("/"); 1807 1808 /* ignore SIGPIPE */ 1809 signal(SIGPIPE, SIG_IGN); 1810 1811 /* Get a connection, either from inetd or a listening TCP socket */ 1812 if (inetd_flag) { 1813 server_accept_inetd(&sock_in, &sock_out); 1814 } else { 1815 platform_pre_listen(); 1816 server_listen(); 1817 1818 if (options.protocol & SSH_PROTO_1) 1819 generate_ephemeral_server_key(); 1820 1821 signal(SIGHUP, sighup_handler); 1822 signal(SIGCHLD, main_sigchld_handler); 1823 signal(SIGTERM, sigterm_handler); 1824 signal(SIGQUIT, sigterm_handler); 1825 1826 /* 1827 * Write out the pid file after the sigterm handler 1828 * is setup and the listen sockets are bound 1829 */ 1830 if (!debug_flag) { 1831 FILE *f = fopen(options.pid_file, "w"); 1832 1833 if (f == NULL) { 1834 error("Couldn't create pid file \"%s\": %s", 1835 options.pid_file, strerror(errno)); 1836 } else { 1837 fprintf(f, "%ld\n", (long) getpid()); 1838 fclose(f); 1839 } 1840 } 1841 1842 /* Accept a connection and return in a forked child */ 1843 server_accept_loop(&sock_in, &sock_out, 1844 &newsock, config_s); 1845 } 1846 1847 /* This is the child processing a new connection. */ 1848 setproctitle("%s", "[accepted]"); 1849 1850 /* 1851 * Initialize the resolver. This may not happen automatically 1852 * before privsep chroot(). 1853 */ 1854 if ((_res.options & RES_INIT) == 0) { 1855 debug("res_init()"); 1856 res_init(); 1857 } 1858 1859 /* 1860 * Create a new session and process group since the 4.4BSD 1861 * setlogin() affects the entire process group. We don't 1862 * want the child to be able to affect the parent. 1863 */ 1864 #if !defined(SSHD_ACQUIRES_CTTY) 1865 /* 1866 * If setsid is called, on some platforms sshd will later acquire a 1867 * controlling terminal which will result in "could not set 1868 * controlling tty" errors. 1869 */ 1870 if (!debug_flag && !inetd_flag && setsid() < 0) 1871 error("setsid: %.100s", strerror(errno)); 1872 #endif 1873 1874 if (rexec_flag) { 1875 int fd; 1876 1877 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1878 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1879 dup2(newsock, STDIN_FILENO); 1880 dup2(STDIN_FILENO, STDOUT_FILENO); 1881 if (startup_pipe == -1) 1882 close(REEXEC_STARTUP_PIPE_FD); 1883 else 1884 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1885 1886 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1887 close(config_s[1]); 1888 if (startup_pipe != -1) 1889 close(startup_pipe); 1890 1891 execv(rexec_argv[0], rexec_argv); 1892 1893 /* Reexec has failed, fall back and continue */ 1894 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1895 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1896 log_init(__progname, options.log_level, 1897 options.log_facility, log_stderr); 1898 1899 /* Clean up fds */ 1900 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1901 close(config_s[1]); 1902 close(REEXEC_CONFIG_PASS_FD); 1903 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1904 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1905 dup2(fd, STDIN_FILENO); 1906 dup2(fd, STDOUT_FILENO); 1907 if (fd > STDERR_FILENO) 1908 close(fd); 1909 } 1910 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1911 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1912 } 1913 1914 /* Executed child processes don't need these. */ 1915 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1916 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1917 1918 /* 1919 * Disable the key regeneration alarm. We will not regenerate the 1920 * key since we are no longer in a position to give it to anyone. We 1921 * will not restart on SIGHUP since it no longer makes sense. 1922 */ 1923 alarm(0); 1924 signal(SIGALRM, SIG_DFL); 1925 signal(SIGHUP, SIG_DFL); 1926 signal(SIGTERM, SIG_DFL); 1927 signal(SIGQUIT, SIG_DFL); 1928 signal(SIGCHLD, SIG_DFL); 1929 signal(SIGINT, SIG_DFL); 1930 1931 /* 1932 * Register our connection. This turns encryption off because we do 1933 * not have a key. 1934 */ 1935 packet_set_connection(sock_in, sock_out); 1936 packet_set_server(); 1937 1938 /* Set SO_KEEPALIVE if requested. */ 1939 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1940 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1941 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1942 1943 if ((remote_port = get_remote_port()) < 0) { 1944 debug("get_remote_port failed"); 1945 cleanup_exit(255); 1946 } 1947 1948 /* 1949 * We use get_canonical_hostname with usedns = 0 instead of 1950 * get_remote_ipaddr here so IP options will be checked. 1951 */ 1952 (void) get_canonical_hostname(0); 1953 /* 1954 * The rest of the code depends on the fact that 1955 * get_remote_ipaddr() caches the remote ip, even if 1956 * the socket goes away. 1957 */ 1958 remote_ip = get_remote_ipaddr(); 1959 1960 #ifdef SSH_AUDIT_EVENTS 1961 audit_connection_from(remote_ip, remote_port); 1962 #endif 1963 #ifdef LIBWRAP 1964 allow_severity = options.log_facility|LOG_INFO; 1965 deny_severity = options.log_facility|LOG_WARNING; 1966 /* Check whether logins are denied from this host. */ 1967 if (packet_connection_is_on_socket()) { 1968 struct request_info req; 1969 1970 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 1971 fromhost(&req); 1972 1973 if (!hosts_access(&req)) { 1974 debug("Connection refused by tcp wrapper"); 1975 refuse(&req); 1976 /* NOTREACHED */ 1977 fatal("libwrap refuse returns"); 1978 } 1979 } 1980 #endif /* LIBWRAP */ 1981 1982 /* Log the connection. */ 1983 verbose("Connection from %.500s port %d", remote_ip, remote_port); 1984 1985 /* set the HPN options for the child */ 1986 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size); 1987 1988 /* 1989 * We don't want to listen forever unless the other side 1990 * successfully authenticates itself. So we set up an alarm which is 1991 * cleared after successful authentication. A limit of zero 1992 * indicates no limit. Note that we don't set the alarm in debugging 1993 * mode; it is just annoying to have the server exit just when you 1994 * are about to discover the bug. 1995 */ 1996 signal(SIGALRM, grace_alarm_handler); 1997 if (!debug_flag) 1998 alarm(options.login_grace_time); 1999 2000 sshd_exchange_identification(sock_in, sock_out); 2001 2002 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 2003 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 2004 generate_ephemeral_server_key(); 2005 2006 packet_set_nonblocking(); 2007 2008 /* allocate authentication context */ 2009 authctxt = xcalloc(1, sizeof(*authctxt)); 2010 2011 authctxt->loginmsg = &loginmsg; 2012 2013 /* XXX global for cleanup, access from other modules */ 2014 the_authctxt = authctxt; 2015 2016 /* prepare buffer to collect messages to display to user after login */ 2017 buffer_init(&loginmsg); 2018 auth_debug_reset(); 2019 2020 if (use_privsep) 2021 if (privsep_preauth(authctxt) == 1) 2022 goto authenticated; 2023 2024 /* perform the key exchange */ 2025 /* authenticate user and start session */ 2026 if (compat20) { 2027 do_ssh2_kex(); 2028 do_authentication2(authctxt); 2029 } else { 2030 do_ssh1_kex(); 2031 do_authentication(authctxt); 2032 } 2033 /* 2034 * If we use privilege separation, the unprivileged child transfers 2035 * the current keystate and exits 2036 */ 2037 if (use_privsep) { 2038 mm_send_keystate(pmonitor); 2039 exit(0); 2040 } 2041 2042 authenticated: 2043 /* 2044 * Cancel the alarm we set to limit the time taken for 2045 * authentication. 2046 */ 2047 alarm(0); 2048 signal(SIGALRM, SIG_DFL); 2049 authctxt->authenticated = 1; 2050 if (startup_pipe != -1) { 2051 close(startup_pipe); 2052 startup_pipe = -1; 2053 } 2054 2055 #ifdef SSH_AUDIT_EVENTS 2056 audit_event(SSH_AUTH_SUCCESS); 2057 #endif 2058 2059 #ifdef GSSAPI 2060 if (options.gss_authentication) { 2061 temporarily_use_uid(authctxt->pw); 2062 ssh_gssapi_storecreds(); 2063 restore_uid(); 2064 } 2065 #endif 2066 #ifdef USE_PAM 2067 if (options.use_pam) { 2068 do_pam_setcred(1); 2069 do_pam_session(); 2070 } 2071 #endif 2072 2073 /* 2074 * In privilege separation, we fork another child and prepare 2075 * file descriptor passing. 2076 */ 2077 if (use_privsep) { 2078 privsep_postauth(authctxt); 2079 /* the monitor process [priv] will not return */ 2080 if (!compat20) 2081 destroy_sensitive_data(); 2082 } 2083 2084 packet_set_timeout(options.client_alive_interval, 2085 options.client_alive_count_max); 2086 2087 /* Start session. */ 2088 do_authenticated(authctxt); 2089 2090 /* The connection has been terminated. */ 2091 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 2092 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 2093 verbose("Transferred: sent %llu, received %llu bytes", 2094 (unsigned long long)obytes, (unsigned long long)ibytes); 2095 2096 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2097 2098 #ifdef USE_PAM 2099 if (options.use_pam) 2100 finish_pam(); 2101 #endif /* USE_PAM */ 2102 2103 #ifdef SSH_AUDIT_EVENTS 2104 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2105 #endif 2106 2107 packet_close(); 2108 2109 if (use_privsep) 2110 mm_terminate(); 2111 2112 exit(0); 2113 } 2114 2115 /* 2116 * Decrypt session_key_int using our private server key and private host key 2117 * (key with larger modulus first). 2118 */ 2119 int 2120 ssh1_session_key(BIGNUM *session_key_int) 2121 { 2122 int rsafail = 0; 2123 2124 if (BN_cmp(sensitive_data.server_key->rsa->n, 2125 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2126 /* Server key has bigger modulus. */ 2127 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2128 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2129 SSH_KEY_BITS_RESERVED) { 2130 fatal("do_connection: %s: " 2131 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2132 get_remote_ipaddr(), 2133 BN_num_bits(sensitive_data.server_key->rsa->n), 2134 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2135 SSH_KEY_BITS_RESERVED); 2136 } 2137 if (rsa_private_decrypt(session_key_int, session_key_int, 2138 sensitive_data.server_key->rsa) <= 0) 2139 rsafail++; 2140 if (rsa_private_decrypt(session_key_int, session_key_int, 2141 sensitive_data.ssh1_host_key->rsa) <= 0) 2142 rsafail++; 2143 } else { 2144 /* Host key has bigger modulus (or they are equal). */ 2145 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2146 BN_num_bits(sensitive_data.server_key->rsa->n) + 2147 SSH_KEY_BITS_RESERVED) { 2148 fatal("do_connection: %s: " 2149 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2150 get_remote_ipaddr(), 2151 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2152 BN_num_bits(sensitive_data.server_key->rsa->n), 2153 SSH_KEY_BITS_RESERVED); 2154 } 2155 if (rsa_private_decrypt(session_key_int, session_key_int, 2156 sensitive_data.ssh1_host_key->rsa) < 0) 2157 rsafail++; 2158 if (rsa_private_decrypt(session_key_int, session_key_int, 2159 sensitive_data.server_key->rsa) < 0) 2160 rsafail++; 2161 } 2162 return (rsafail); 2163 } 2164 /* 2165 * SSH1 key exchange 2166 */ 2167 static void 2168 do_ssh1_kex(void) 2169 { 2170 int i, len; 2171 int rsafail = 0; 2172 BIGNUM *session_key_int; 2173 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2174 u_char cookie[8]; 2175 u_int cipher_type, auth_mask, protocol_flags; 2176 2177 /* 2178 * Generate check bytes that the client must send back in the user 2179 * packet in order for it to be accepted; this is used to defy ip 2180 * spoofing attacks. Note that this only works against somebody 2181 * doing IP spoofing from a remote machine; any machine on the local 2182 * network can still see outgoing packets and catch the random 2183 * cookie. This only affects rhosts authentication, and this is one 2184 * of the reasons why it is inherently insecure. 2185 */ 2186 arc4random_buf(cookie, sizeof(cookie)); 2187 2188 /* 2189 * Send our public key. We include in the packet 64 bits of random 2190 * data that must be matched in the reply in order to prevent IP 2191 * spoofing. 2192 */ 2193 packet_start(SSH_SMSG_PUBLIC_KEY); 2194 for (i = 0; i < 8; i++) 2195 packet_put_char(cookie[i]); 2196 2197 /* Store our public server RSA key. */ 2198 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2199 packet_put_bignum(sensitive_data.server_key->rsa->e); 2200 packet_put_bignum(sensitive_data.server_key->rsa->n); 2201 2202 /* Store our public host RSA key. */ 2203 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2204 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2205 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2206 2207 /* Put protocol flags. */ 2208 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2209 2210 /* Declare which ciphers we support. */ 2211 packet_put_int(cipher_mask_ssh1(0)); 2212 2213 /* Declare supported authentication types. */ 2214 auth_mask = 0; 2215 if (options.rhosts_rsa_authentication) 2216 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2217 if (options.rsa_authentication) 2218 auth_mask |= 1 << SSH_AUTH_RSA; 2219 if (options.challenge_response_authentication == 1) 2220 auth_mask |= 1 << SSH_AUTH_TIS; 2221 if (options.password_authentication) 2222 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2223 packet_put_int(auth_mask); 2224 2225 /* Send the packet and wait for it to be sent. */ 2226 packet_send(); 2227 packet_write_wait(); 2228 2229 debug("Sent %d bit server key and %d bit host key.", 2230 BN_num_bits(sensitive_data.server_key->rsa->n), 2231 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2232 2233 /* Read clients reply (cipher type and session key). */ 2234 packet_read_expect(SSH_CMSG_SESSION_KEY); 2235 2236 /* Get cipher type and check whether we accept this. */ 2237 cipher_type = packet_get_char(); 2238 2239 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2240 packet_disconnect("Warning: client selects unsupported cipher."); 2241 2242 /* Get check bytes from the packet. These must match those we 2243 sent earlier with the public key packet. */ 2244 for (i = 0; i < 8; i++) 2245 if (cookie[i] != packet_get_char()) 2246 packet_disconnect("IP Spoofing check bytes do not match."); 2247 2248 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2249 2250 /* Get the encrypted integer. */ 2251 if ((session_key_int = BN_new()) == NULL) 2252 fatal("do_ssh1_kex: BN_new failed"); 2253 packet_get_bignum(session_key_int); 2254 2255 protocol_flags = packet_get_int(); 2256 packet_set_protocol_flags(protocol_flags); 2257 packet_check_eom(); 2258 2259 /* Decrypt session_key_int using host/server keys */ 2260 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2261 2262 /* 2263 * Extract session key from the decrypted integer. The key is in the 2264 * least significant 256 bits of the integer; the first byte of the 2265 * key is in the highest bits. 2266 */ 2267 if (!rsafail) { 2268 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2269 len = BN_num_bytes(session_key_int); 2270 if (len < 0 || (u_int)len > sizeof(session_key)) { 2271 error("do_ssh1_kex: bad session key len from %s: " 2272 "session_key_int %d > sizeof(session_key) %lu", 2273 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2274 rsafail++; 2275 } else { 2276 memset(session_key, 0, sizeof(session_key)); 2277 BN_bn2bin(session_key_int, 2278 session_key + sizeof(session_key) - len); 2279 2280 derive_ssh1_session_id( 2281 sensitive_data.ssh1_host_key->rsa->n, 2282 sensitive_data.server_key->rsa->n, 2283 cookie, session_id); 2284 /* 2285 * Xor the first 16 bytes of the session key with the 2286 * session id. 2287 */ 2288 for (i = 0; i < 16; i++) 2289 session_key[i] ^= session_id[i]; 2290 } 2291 } 2292 if (rsafail) { 2293 int bytes = BN_num_bytes(session_key_int); 2294 u_char *buf = xmalloc(bytes); 2295 MD5_CTX md; 2296 2297 logit("do_connection: generating a fake encryption key"); 2298 BN_bn2bin(session_key_int, buf); 2299 MD5_Init(&md); 2300 MD5_Update(&md, buf, bytes); 2301 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2302 MD5_Final(session_key, &md); 2303 MD5_Init(&md); 2304 MD5_Update(&md, session_key, 16); 2305 MD5_Update(&md, buf, bytes); 2306 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2307 MD5_Final(session_key + 16, &md); 2308 memset(buf, 0, bytes); 2309 xfree(buf); 2310 for (i = 0; i < 16; i++) 2311 session_id[i] = session_key[i] ^ session_key[i + 16]; 2312 } 2313 /* Destroy the private and public keys. No longer. */ 2314 destroy_sensitive_data(); 2315 2316 if (use_privsep) 2317 mm_ssh1_session_id(session_id); 2318 2319 /* Destroy the decrypted integer. It is no longer needed. */ 2320 BN_clear_free(session_key_int); 2321 2322 /* Set the session key. From this on all communications will be encrypted. */ 2323 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2324 2325 /* Destroy our copy of the session key. It is no longer needed. */ 2326 memset(session_key, 0, sizeof(session_key)); 2327 2328 debug("Received session key; encryption turned on."); 2329 2330 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2331 packet_start(SSH_SMSG_SUCCESS); 2332 packet_send(); 2333 packet_write_wait(); 2334 } 2335 2336 /* 2337 * SSH2 key exchange: diffie-hellman-group1-sha1 2338 */ 2339 static void 2340 do_ssh2_kex(void) 2341 { 2342 Kex *kex; 2343 2344 myflag++; 2345 debug ("MYFLAG IS %d", myflag); 2346 if (options.ciphers != NULL) { 2347 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2348 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2349 } else if (options.none_enabled == 1) { 2350 debug ("WARNING: None cipher enabled"); 2351 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2352 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE; 2353 } 2354 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2355 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2356 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2357 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2358 2359 if (options.macs != NULL) { 2360 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2361 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2362 } 2363 if (options.compression == COMP_NONE) { 2364 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2365 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2366 } else if (options.compression == COMP_DELAYED) { 2367 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2368 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2369 } 2370 if (options.kex_algorithms != NULL) 2371 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 2372 2373 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); 2374 2375 /* start key exchange */ 2376 kex = kex_setup(myproposal); 2377 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2378 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2379 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2380 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2381 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2382 kex->server = 1; 2383 kex->client_version_string=client_version_string; 2384 kex->server_version_string=server_version_string; 2385 kex->load_host_public_key=&get_hostkey_public_by_type; 2386 kex->load_host_private_key=&get_hostkey_private_by_type; 2387 kex->host_key_index=&get_hostkey_index; 2388 2389 xxx_kex = kex; 2390 2391 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2392 2393 session_id2 = kex->session_id; 2394 session_id2_len = kex->session_id_len; 2395 2396 #ifdef DEBUG_KEXDH 2397 /* send 1st encrypted/maced/compressed message */ 2398 packet_start(SSH2_MSG_IGNORE); 2399 packet_put_cstring("markus"); 2400 packet_send(); 2401 packet_write_wait(); 2402 #endif 2403 debug("KEX done"); 2404 } 2405 2406 /* server specific fatal cleanup */ 2407 void 2408 cleanup_exit(int i) 2409 { 2410 if (the_authctxt) 2411 do_cleanup(the_authctxt); 2412 #ifdef SSH_AUDIT_EVENTS 2413 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2414 if (!use_privsep || mm_is_monitor()) 2415 audit_event(SSH_CONNECTION_ABANDON); 2416 #endif 2417 _exit(i); 2418 } 2419