1 /* $OpenBSD: sshd.c,v 1.393 2012/07/10 02:19:15 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 int privsep_is_preauth = 1; 247 248 /* global authentication context */ 249 Authctxt *the_authctxt = NULL; 250 251 /* sshd_config buffer */ 252 Buffer cfg; 253 254 /* message to be displayed after login */ 255 Buffer loginmsg; 256 257 /* Unprivileged user */ 258 struct passwd *privsep_pw = NULL; 259 260 /* Prototypes for various functions defined later in this file. */ 261 void destroy_sensitive_data(void); 262 void demote_sensitive_data(void); 263 264 static void do_ssh1_kex(void); 265 static void do_ssh2_kex(void); 266 267 /* 268 * Close all listening sockets 269 */ 270 static void 271 close_listen_socks(void) 272 { 273 int i; 274 275 for (i = 0; i < num_listen_socks; i++) 276 close(listen_socks[i]); 277 num_listen_socks = -1; 278 } 279 280 static void 281 close_startup_pipes(void) 282 { 283 int i; 284 285 if (startup_pipes) 286 for (i = 0; i < options.max_startups; i++) 287 if (startup_pipes[i] != -1) 288 close(startup_pipes[i]); 289 } 290 291 /* 292 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 293 * the effect is to reread the configuration file (and to regenerate 294 * the server key). 295 */ 296 297 /*ARGSUSED*/ 298 static void 299 sighup_handler(int sig) 300 { 301 int save_errno = errno; 302 303 received_sighup = 1; 304 signal(SIGHUP, sighup_handler); 305 errno = save_errno; 306 } 307 308 /* 309 * Called from the main program after receiving SIGHUP. 310 * Restarts the server. 311 */ 312 static void 313 sighup_restart(void) 314 { 315 logit("Received SIGHUP; restarting."); 316 close_listen_socks(); 317 close_startup_pipes(); 318 alarm(0); /* alarm timer persists across exec */ 319 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 320 execv(saved_argv[0], saved_argv); 321 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 322 strerror(errno)); 323 exit(1); 324 } 325 326 /* 327 * Generic signal handler for terminating signals in the master daemon. 328 */ 329 /*ARGSUSED*/ 330 static void 331 sigterm_handler(int sig) 332 { 333 received_sigterm = sig; 334 } 335 336 /* 337 * SIGCHLD handler. This is called whenever a child dies. This will then 338 * reap any zombies left by exited children. 339 */ 340 /*ARGSUSED*/ 341 static void 342 main_sigchld_handler(int sig) 343 { 344 int save_errno = errno; 345 pid_t pid; 346 int status; 347 348 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 349 (pid < 0 && errno == EINTR)) 350 ; 351 352 signal(SIGCHLD, main_sigchld_handler); 353 errno = save_errno; 354 } 355 356 /* 357 * Signal handler for the alarm after the login grace period has expired. 358 */ 359 /*ARGSUSED*/ 360 static void 361 grace_alarm_handler(int sig) 362 { 363 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 364 kill(pmonitor->m_pid, SIGALRM); 365 366 /* Log error and exit. */ 367 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 368 } 369 370 /* 371 * Signal handler for the key regeneration alarm. Note that this 372 * alarm only occurs in the daemon waiting for connections, and it does not 373 * do anything with the private key or random state before forking. 374 * Thus there should be no concurrency control/asynchronous execution 375 * problems. 376 */ 377 static void 378 generate_ephemeral_server_key(void) 379 { 380 verbose("Generating %s%d bit RSA key.", 381 sensitive_data.server_key ? "new " : "", options.server_key_bits); 382 if (sensitive_data.server_key != NULL) 383 key_free(sensitive_data.server_key); 384 sensitive_data.server_key = key_generate(KEY_RSA1, 385 options.server_key_bits); 386 verbose("RSA key generation complete."); 387 388 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 389 arc4random_stir(); 390 } 391 392 /*ARGSUSED*/ 393 static void 394 key_regeneration_alarm(int sig) 395 { 396 int save_errno = errno; 397 398 signal(SIGALRM, SIG_DFL); 399 errno = save_errno; 400 key_do_regen = 1; 401 } 402 403 static void 404 sshd_exchange_identification(int sock_in, int sock_out) 405 { 406 u_int i; 407 int mismatch; 408 int remote_major, remote_minor; 409 int major, minor; 410 char *s, *newline = "\n"; 411 char buf[256]; /* Must not be larger than remote_version. */ 412 char remote_version[256]; /* Must be at least as big as buf. */ 413 414 if ((options.protocol & SSH_PROTO_1) && 415 (options.protocol & SSH_PROTO_2)) { 416 major = PROTOCOL_MAJOR_1; 417 minor = 99; 418 } else if (options.protocol & SSH_PROTO_2) { 419 major = PROTOCOL_MAJOR_2; 420 minor = PROTOCOL_MINOR_2; 421 newline = "\r\n"; 422 } else { 423 major = PROTOCOL_MAJOR_1; 424 minor = PROTOCOL_MINOR_1; 425 } 426 427 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s", 428 major, minor, SSH_VERSION, 429 *options.version_addendum == '\0' ? "" : " ", 430 options.version_addendum, newline); 431 432 /* Send our protocol version identification. */ 433 if (roaming_atomicio(vwrite, sock_out, server_version_string, 434 strlen(server_version_string)) 435 != strlen(server_version_string)) { 436 logit("Could not write ident string to %s", get_remote_ipaddr()); 437 cleanup_exit(255); 438 } 439 440 /* Read other sides version identification. */ 441 memset(buf, 0, sizeof(buf)); 442 for (i = 0; i < sizeof(buf) - 1; i++) { 443 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 444 logit("Did not receive identification string from %s", 445 get_remote_ipaddr()); 446 cleanup_exit(255); 447 } 448 if (buf[i] == '\r') { 449 buf[i] = 0; 450 /* Kludge for F-Secure Macintosh < 1.0.2 */ 451 if (i == 12 && 452 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 453 break; 454 continue; 455 } 456 if (buf[i] == '\n') { 457 buf[i] = 0; 458 break; 459 } 460 } 461 buf[sizeof(buf) - 1] = 0; 462 client_version_string = xstrdup(buf); 463 464 /* 465 * Check that the versions match. In future this might accept 466 * several versions and set appropriate flags to handle them. 467 */ 468 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 469 &remote_major, &remote_minor, remote_version) != 3) { 470 s = "Protocol mismatch.\n"; 471 (void) atomicio(vwrite, sock_out, s, strlen(s)); 472 close(sock_in); 473 close(sock_out); 474 logit("Bad protocol version identification '%.100s' from %s", 475 client_version_string, get_remote_ipaddr()); 476 cleanup_exit(255); 477 } 478 debug("Client protocol version %d.%d; client software version %.100s", 479 remote_major, remote_minor, remote_version); 480 logit("SSH: Server;Ltype: Version;Remote: %s-%d;Protocol: %d.%d;Client: %.100s", 481 get_remote_ipaddr(), get_remote_port(), 482 remote_major, remote_minor, remote_version); 483 484 compat_datafellows(remote_version); 485 486 if (datafellows & SSH_BUG_PROBE) { 487 logit("probed from %s with %s. Don't panic.", 488 get_remote_ipaddr(), client_version_string); 489 cleanup_exit(255); 490 } 491 492 if (datafellows & SSH_BUG_SCANNER) { 493 logit("scanned from %s with %s. Don't panic.", 494 get_remote_ipaddr(), client_version_string); 495 cleanup_exit(255); 496 } 497 498 mismatch = 0; 499 switch (remote_major) { 500 case 1: 501 if (remote_minor == 99) { 502 if (options.protocol & SSH_PROTO_2) 503 enable_compat20(); 504 else 505 mismatch = 1; 506 break; 507 } 508 if (!(options.protocol & SSH_PROTO_1)) { 509 mismatch = 1; 510 break; 511 } 512 if (remote_minor < 3) { 513 packet_disconnect("Your ssh version is too old and " 514 "is no longer supported. Please install a newer version."); 515 } else if (remote_minor == 3) { 516 /* note that this disables agent-forwarding */ 517 enable_compat13(); 518 } 519 break; 520 case 2: 521 if (options.protocol & SSH_PROTO_2) { 522 enable_compat20(); 523 break; 524 } 525 /* FALLTHROUGH */ 526 default: 527 mismatch = 1; 528 break; 529 } 530 chop(server_version_string); 531 debug("Local version string %.200s", server_version_string); 532 533 if (mismatch) { 534 s = "Protocol major versions differ.\n"; 535 (void) atomicio(vwrite, sock_out, s, strlen(s)); 536 close(sock_in); 537 close(sock_out); 538 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 539 get_remote_ipaddr(), 540 server_version_string, client_version_string); 541 cleanup_exit(255); 542 } 543 } 544 545 /* Destroy the host and server keys. They will no longer be needed. */ 546 void 547 destroy_sensitive_data(void) 548 { 549 int i; 550 551 if (sensitive_data.server_key) { 552 key_free(sensitive_data.server_key); 553 sensitive_data.server_key = NULL; 554 } 555 for (i = 0; i < options.num_host_key_files; i++) { 556 if (sensitive_data.host_keys[i]) { 557 key_free(sensitive_data.host_keys[i]); 558 sensitive_data.host_keys[i] = NULL; 559 } 560 if (sensitive_data.host_certificates[i]) { 561 key_free(sensitive_data.host_certificates[i]); 562 sensitive_data.host_certificates[i] = NULL; 563 } 564 } 565 sensitive_data.ssh1_host_key = NULL; 566 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); 567 } 568 569 /* Demote private to public keys for network child */ 570 void 571 demote_sensitive_data(void) 572 { 573 Key *tmp; 574 int i; 575 576 if (sensitive_data.server_key) { 577 tmp = key_demote(sensitive_data.server_key); 578 key_free(sensitive_data.server_key); 579 sensitive_data.server_key = tmp; 580 } 581 582 for (i = 0; i < options.num_host_key_files; i++) { 583 if (sensitive_data.host_keys[i]) { 584 tmp = key_demote(sensitive_data.host_keys[i]); 585 key_free(sensitive_data.host_keys[i]); 586 sensitive_data.host_keys[i] = tmp; 587 if (tmp->type == KEY_RSA1) 588 sensitive_data.ssh1_host_key = tmp; 589 } 590 /* Certs do not need demotion */ 591 } 592 593 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 594 } 595 596 static void 597 privsep_preauth_child(void) 598 { 599 u_int32_t rnd[256]; 600 gid_t gidset[1]; 601 602 /* Enable challenge-response authentication for privilege separation */ 603 privsep_challenge_enable(); 604 605 arc4random_stir(); 606 arc4random_buf(rnd, sizeof(rnd)); 607 RAND_seed(rnd, sizeof(rnd)); 608 609 /* Demote the private keys to public keys. */ 610 demote_sensitive_data(); 611 612 /* Change our root directory */ 613 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 614 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 615 strerror(errno)); 616 if (chdir("/") == -1) 617 fatal("chdir(\"/\"): %s", strerror(errno)); 618 619 /* Drop our privileges */ 620 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 621 (u_int)privsep_pw->pw_gid); 622 #if 0 623 /* XXX not ready, too heavy after chroot */ 624 do_setusercontext(privsep_pw); 625 #else 626 gidset[0] = privsep_pw->pw_gid; 627 if (setgroups(1, gidset) < 0) 628 fatal("setgroups: %.100s", strerror(errno)); 629 permanently_set_uid(privsep_pw); 630 #endif 631 } 632 633 static int 634 privsep_preauth(Authctxt *authctxt) 635 { 636 int status; 637 pid_t pid; 638 struct ssh_sandbox *box = NULL; 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 if (use_privsep == PRIVSEP_ON) 646 box = ssh_sandbox_init(); 647 pid = fork(); 648 if (pid == -1) { 649 fatal("fork of unprivileged child failed"); 650 } else if (pid != 0) { 651 debug2("Network child is on pid %ld", (long)pid); 652 653 pmonitor->m_pid = pid; 654 if (box != NULL) 655 ssh_sandbox_parent_preauth(box, pid); 656 monitor_child_preauth(authctxt, pmonitor); 657 658 /* Sync memory */ 659 monitor_sync(pmonitor); 660 661 /* Wait for the child's exit status */ 662 while (waitpid(pid, &status, 0) < 0) { 663 if (errno == EINTR) 664 continue; 665 pmonitor->m_pid = -1; 666 fatal("%s: waitpid: %s", __func__, strerror(errno)); 667 } 668 privsep_is_preauth = 0; 669 pmonitor->m_pid = -1; 670 if (WIFEXITED(status)) { 671 if (WEXITSTATUS(status) != 0) 672 fatal("%s: preauth child exited with status %d", 673 __func__, WEXITSTATUS(status)); 674 } else if (WIFSIGNALED(status)) 675 fatal("%s: preauth child terminated by signal %d", 676 __func__, WTERMSIG(status)); 677 if (box != NULL) 678 ssh_sandbox_parent_finish(box); 679 return 1; 680 } else { 681 /* child */ 682 close(pmonitor->m_sendfd); 683 close(pmonitor->m_log_recvfd); 684 685 /* Arrange for logging to be sent to the monitor */ 686 set_log_handler(mm_log_handler, pmonitor); 687 688 /* Demote the child */ 689 if (getuid() == 0 || geteuid() == 0) 690 privsep_preauth_child(); 691 setproctitle("%s", "[net]"); 692 if (box != NULL) 693 ssh_sandbox_child(box); 694 695 return 0; 696 } 697 } 698 699 static void 700 privsep_postauth(Authctxt *authctxt) 701 { 702 u_int32_t rnd[256]; 703 704 #ifdef DISABLE_FD_PASSING 705 if (1) { 706 #else 707 if (authctxt->pw->pw_uid == 0 || options.use_login) { 708 #endif 709 /* File descriptor passing is broken or root login */ 710 use_privsep = 0; 711 goto skip; 712 } 713 714 /* New socket pair */ 715 monitor_reinit(pmonitor); 716 717 pmonitor->m_pid = fork(); 718 if (pmonitor->m_pid == -1) 719 fatal("fork of unprivileged child failed"); 720 else if (pmonitor->m_pid != 0) { 721 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 722 buffer_clear(&loginmsg); 723 monitor_child_postauth(pmonitor); 724 725 /* NEVERREACHED */ 726 exit(0); 727 } 728 729 /* child */ 730 731 close(pmonitor->m_sendfd); 732 pmonitor->m_sendfd = -1; 733 734 /* Demote the private keys to public keys. */ 735 demote_sensitive_data(); 736 737 arc4random_stir(); 738 arc4random_buf(rnd, sizeof(rnd)); 739 RAND_seed(rnd, sizeof(rnd)); 740 741 /* Drop privileges */ 742 do_setusercontext(authctxt->pw); 743 744 skip: 745 /* It is safe now to apply the key state */ 746 monitor_apply_keystate(pmonitor); 747 748 /* 749 * Tell the packet layer that authentication was successful, since 750 * this information is not part of the key state. 751 */ 752 packet_set_authenticated(); 753 } 754 755 static char * 756 list_hostkey_types(void) 757 { 758 Buffer b; 759 const char *p; 760 char *ret; 761 int i; 762 Key *key; 763 764 buffer_init(&b); 765 for (i = 0; i < options.num_host_key_files; i++) { 766 key = sensitive_data.host_keys[i]; 767 if (key == NULL) 768 continue; 769 switch (key->type) { 770 case KEY_RSA: 771 case KEY_DSA: 772 case KEY_ECDSA: 773 if (buffer_len(&b) > 0) 774 buffer_append(&b, ",", 1); 775 p = key_ssh_name(key); 776 buffer_append(&b, p, strlen(p)); 777 break; 778 } 779 /* If the private key has a cert peer, then list that too */ 780 key = sensitive_data.host_certificates[i]; 781 if (key == NULL) 782 continue; 783 switch (key->type) { 784 case KEY_RSA_CERT_V00: 785 case KEY_DSA_CERT_V00: 786 case KEY_RSA_CERT: 787 case KEY_DSA_CERT: 788 case KEY_ECDSA_CERT: 789 if (buffer_len(&b) > 0) 790 buffer_append(&b, ",", 1); 791 p = key_ssh_name(key); 792 buffer_append(&b, p, strlen(p)); 793 break; 794 } 795 } 796 buffer_append(&b, "\0", 1); 797 ret = xstrdup(buffer_ptr(&b)); 798 buffer_free(&b); 799 debug("list_hostkey_types: %s", ret); 800 return ret; 801 } 802 803 static Key * 804 get_hostkey_by_type(int type, int need_private) 805 { 806 int i; 807 Key *key; 808 809 for (i = 0; i < options.num_host_key_files; i++) { 810 switch (type) { 811 case KEY_RSA_CERT_V00: 812 case KEY_DSA_CERT_V00: 813 case KEY_RSA_CERT: 814 case KEY_DSA_CERT: 815 case KEY_ECDSA_CERT: 816 key = sensitive_data.host_certificates[i]; 817 break; 818 default: 819 key = sensitive_data.host_keys[i]; 820 break; 821 } 822 if (key != NULL && key->type == type) 823 return need_private ? 824 sensitive_data.host_keys[i] : key; 825 } 826 return NULL; 827 } 828 829 Key * 830 get_hostkey_public_by_type(int type) 831 { 832 return get_hostkey_by_type(type, 0); 833 } 834 835 Key * 836 get_hostkey_private_by_type(int type) 837 { 838 return get_hostkey_by_type(type, 1); 839 } 840 841 Key * 842 get_hostkey_by_index(int ind) 843 { 844 if (ind < 0 || ind >= options.num_host_key_files) 845 return (NULL); 846 return (sensitive_data.host_keys[ind]); 847 } 848 849 int 850 get_hostkey_index(Key *key) 851 { 852 int i; 853 854 for (i = 0; i < options.num_host_key_files; i++) { 855 if (key_is_cert(key)) { 856 if (key == sensitive_data.host_certificates[i]) 857 return (i); 858 } else { 859 if (key == sensitive_data.host_keys[i]) 860 return (i); 861 } 862 } 863 return (-1); 864 } 865 866 /* 867 * returns 1 if connection should be dropped, 0 otherwise. 868 * dropping starts at connection #max_startups_begin with a probability 869 * of (max_startups_rate/100). the probability increases linearly until 870 * all connections are dropped for startups > max_startups 871 */ 872 static int 873 drop_connection(int startups) 874 { 875 int p, r; 876 877 if (startups < options.max_startups_begin) 878 return 0; 879 if (startups >= options.max_startups) 880 return 1; 881 if (options.max_startups_rate == 100) 882 return 1; 883 884 p = 100 - options.max_startups_rate; 885 p *= startups - options.max_startups_begin; 886 p /= options.max_startups - options.max_startups_begin; 887 p += options.max_startups_rate; 888 r = arc4random_uniform(100); 889 890 debug("drop_connection: p %d, r %d", p, r); 891 return (r < p) ? 1 : 0; 892 } 893 894 static void 895 usage(void) 896 { 897 fprintf(stderr, "%s, %s\n", 898 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); 899 fprintf(stderr, 900 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 901 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n" 902 " [-k key_gen_time] [-o option] [-p port] [-u len]\n" 903 ); 904 exit(1); 905 } 906 907 static void 908 send_rexec_state(int fd, Buffer *conf) 909 { 910 Buffer m; 911 912 debug3("%s: entering fd = %d config len %d", __func__, fd, 913 buffer_len(conf)); 914 915 /* 916 * Protocol from reexec master to child: 917 * string configuration 918 * u_int ephemeral_key_follows 919 * bignum e (only if ephemeral_key_follows == 1) 920 * bignum n " 921 * bignum d " 922 * bignum iqmp " 923 * bignum p " 924 * bignum q " 925 * string rngseed (only if OpenSSL is not self-seeded) 926 */ 927 buffer_init(&m); 928 buffer_put_cstring(&m, buffer_ptr(conf)); 929 930 if (sensitive_data.server_key != NULL && 931 sensitive_data.server_key->type == KEY_RSA1) { 932 buffer_put_int(&m, 1); 933 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 934 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 935 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 936 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 937 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 938 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 939 } else 940 buffer_put_int(&m, 0); 941 942 #ifndef OPENSSL_PRNG_ONLY 943 rexec_send_rng_seed(&m); 944 #endif 945 946 if (ssh_msg_send(fd, 0, &m) == -1) 947 fatal("%s: ssh_msg_send failed", __func__); 948 949 buffer_free(&m); 950 951 debug3("%s: done", __func__); 952 } 953 954 static void 955 recv_rexec_state(int fd, Buffer *conf) 956 { 957 Buffer m; 958 char *cp; 959 u_int len; 960 961 debug3("%s: entering fd = %d", __func__, fd); 962 963 buffer_init(&m); 964 965 if (ssh_msg_recv(fd, &m) == -1) 966 fatal("%s: ssh_msg_recv failed", __func__); 967 if (buffer_get_char(&m) != 0) 968 fatal("%s: rexec version mismatch", __func__); 969 970 cp = buffer_get_string(&m, &len); 971 if (conf != NULL) 972 buffer_append(conf, cp, len + 1); 973 xfree(cp); 974 975 if (buffer_get_int(&m)) { 976 if (sensitive_data.server_key != NULL) 977 key_free(sensitive_data.server_key); 978 sensitive_data.server_key = key_new_private(KEY_RSA1); 979 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 980 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 981 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 982 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 983 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 984 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 985 rsa_generate_additional_parameters( 986 sensitive_data.server_key->rsa); 987 } 988 989 #ifndef OPENSSL_PRNG_ONLY 990 rexec_recv_rng_seed(&m); 991 #endif 992 993 buffer_free(&m); 994 995 debug3("%s: done", __func__); 996 } 997 998 /* Accept a connection from inetd */ 999 static void 1000 server_accept_inetd(int *sock_in, int *sock_out) 1001 { 1002 int fd; 1003 1004 startup_pipe = -1; 1005 if (rexeced_flag) { 1006 close(REEXEC_CONFIG_PASS_FD); 1007 *sock_in = *sock_out = dup(STDIN_FILENO); 1008 if (!debug_flag) { 1009 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1010 close(REEXEC_STARTUP_PIPE_FD); 1011 } 1012 } else { 1013 *sock_in = dup(STDIN_FILENO); 1014 *sock_out = dup(STDOUT_FILENO); 1015 } 1016 /* 1017 * We intentionally do not close the descriptors 0, 1, and 2 1018 * as our code for setting the descriptors won't work if 1019 * ttyfd happens to be one of those. 1020 */ 1021 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1022 dup2(fd, STDIN_FILENO); 1023 dup2(fd, STDOUT_FILENO); 1024 if (fd > STDOUT_FILENO) 1025 close(fd); 1026 } 1027 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1028 } 1029 1030 /* 1031 * Listen for TCP connections 1032 */ 1033 static void 1034 server_listen(void) 1035 { 1036 int ret, listen_sock, on = 1; 1037 struct addrinfo *ai; 1038 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1039 int socksize; 1040 int socksizelen = sizeof(int); 1041 1042 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1043 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1044 continue; 1045 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1046 fatal("Too many listen sockets. " 1047 "Enlarge MAX_LISTEN_SOCKS"); 1048 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1049 ntop, sizeof(ntop), strport, sizeof(strport), 1050 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1051 error("getnameinfo failed: %.100s", 1052 ssh_gai_strerror(ret)); 1053 continue; 1054 } 1055 /* Create socket for listening. */ 1056 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1057 ai->ai_protocol); 1058 if (listen_sock < 0) { 1059 /* kernel may not support ipv6 */ 1060 verbose("socket: %.100s", strerror(errno)); 1061 continue; 1062 } 1063 if (set_nonblock(listen_sock) == -1) { 1064 close(listen_sock); 1065 continue; 1066 } 1067 /* 1068 * Set socket options. 1069 * Allow local port reuse in TIME_WAIT. 1070 */ 1071 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1072 &on, sizeof(on)) == -1) 1073 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1074 1075 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1076 if (ai->ai_family == AF_INET6) 1077 sock_set_v6only(listen_sock); 1078 1079 debug("Bind to port %s on %s.", strport, ntop); 1080 1081 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, 1082 &socksize, &socksizelen); 1083 debug("Server TCP RWIN socket size: %d", socksize); 1084 debug("HPN Buffer Size: %d", options.hpn_buffer_size); 1085 1086 /* Bind the socket to the desired port. */ 1087 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1088 error("Bind to port %s on %s failed: %.200s.", 1089 strport, ntop, strerror(errno)); 1090 close(listen_sock); 1091 continue; 1092 } 1093 listen_socks[num_listen_socks] = listen_sock; 1094 num_listen_socks++; 1095 1096 /* Start listening on the port. */ 1097 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1098 fatal("listen on [%s]:%s: %.100s", 1099 ntop, strport, strerror(errno)); 1100 logit("Server listening on %s port %s.", ntop, strport); 1101 } 1102 freeaddrinfo(options.listen_addrs); 1103 1104 if (!num_listen_socks) 1105 fatal("Cannot bind any address."); 1106 } 1107 1108 /* 1109 * The main TCP accept loop. Note that, for the non-debug case, returns 1110 * from this function are in a forked subprocess. 1111 */ 1112 static void 1113 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1114 { 1115 fd_set *fdset; 1116 int i, j, ret, maxfd; 1117 int key_used = 0, startups = 0; 1118 int startup_p[2] = { -1 , -1 }; 1119 struct sockaddr_storage from; 1120 socklen_t fromlen; 1121 pid_t pid; 1122 1123 /* setup fd set for accept */ 1124 fdset = NULL; 1125 maxfd = 0; 1126 for (i = 0; i < num_listen_socks; i++) 1127 if (listen_socks[i] > maxfd) 1128 maxfd = listen_socks[i]; 1129 /* pipes connected to unauthenticated childs */ 1130 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1131 for (i = 0; i < options.max_startups; i++) 1132 startup_pipes[i] = -1; 1133 1134 /* 1135 * Stay listening for connections until the system crashes or 1136 * the daemon is killed with a signal. 1137 */ 1138 for (;;) { 1139 if (received_sighup) 1140 sighup_restart(); 1141 if (fdset != NULL) 1142 xfree(fdset); 1143 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1144 sizeof(fd_mask)); 1145 1146 for (i = 0; i < num_listen_socks; i++) 1147 FD_SET(listen_socks[i], fdset); 1148 for (i = 0; i < options.max_startups; i++) 1149 if (startup_pipes[i] != -1) 1150 FD_SET(startup_pipes[i], fdset); 1151 1152 /* Wait in select until there is a connection. */ 1153 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1154 if (ret < 0 && errno != EINTR) 1155 error("select: %.100s", strerror(errno)); 1156 if (received_sigterm) { 1157 logit("Received signal %d; terminating.", 1158 (int) received_sigterm); 1159 close_listen_socks(); 1160 unlink(options.pid_file); 1161 exit(received_sigterm == SIGTERM ? 0 : 255); 1162 } 1163 if (key_used && key_do_regen) { 1164 generate_ephemeral_server_key(); 1165 key_used = 0; 1166 key_do_regen = 0; 1167 } 1168 if (ret < 0) 1169 continue; 1170 1171 for (i = 0; i < options.max_startups; i++) 1172 if (startup_pipes[i] != -1 && 1173 FD_ISSET(startup_pipes[i], fdset)) { 1174 /* 1175 * the read end of the pipe is ready 1176 * if the child has closed the pipe 1177 * after successful authentication 1178 * or if the child has died 1179 */ 1180 close(startup_pipes[i]); 1181 startup_pipes[i] = -1; 1182 startups--; 1183 } 1184 for (i = 0; i < num_listen_socks; i++) { 1185 if (!FD_ISSET(listen_socks[i], fdset)) 1186 continue; 1187 fromlen = sizeof(from); 1188 *newsock = accept(listen_socks[i], 1189 (struct sockaddr *)&from, &fromlen); 1190 if (*newsock < 0) { 1191 if (errno != EINTR && errno != EAGAIN && 1192 errno != EWOULDBLOCK) 1193 error("accept: %.100s", 1194 strerror(errno)); 1195 if (errno == EMFILE || errno == ENFILE) 1196 usleep(100 * 1000); 1197 continue; 1198 } 1199 if (unset_nonblock(*newsock) == -1) { 1200 close(*newsock); 1201 continue; 1202 } 1203 if (drop_connection(startups) == 1) { 1204 debug("drop connection #%d", startups); 1205 close(*newsock); 1206 continue; 1207 } 1208 if (pipe(startup_p) == -1) { 1209 close(*newsock); 1210 continue; 1211 } 1212 1213 if (rexec_flag && socketpair(AF_UNIX, 1214 SOCK_STREAM, 0, config_s) == -1) { 1215 error("reexec socketpair: %s", 1216 strerror(errno)); 1217 close(*newsock); 1218 close(startup_p[0]); 1219 close(startup_p[1]); 1220 continue; 1221 } 1222 1223 for (j = 0; j < options.max_startups; j++) 1224 if (startup_pipes[j] == -1) { 1225 startup_pipes[j] = startup_p[0]; 1226 if (maxfd < startup_p[0]) 1227 maxfd = startup_p[0]; 1228 startups++; 1229 break; 1230 } 1231 1232 /* 1233 * Got connection. Fork a child to handle it, unless 1234 * we are in debugging mode. 1235 */ 1236 if (debug_flag) { 1237 /* 1238 * In debugging mode. Close the listening 1239 * socket, and start processing the 1240 * connection without forking. 1241 */ 1242 debug("Server will not fork when running in debugging mode."); 1243 close_listen_socks(); 1244 *sock_in = *newsock; 1245 *sock_out = *newsock; 1246 close(startup_p[0]); 1247 close(startup_p[1]); 1248 startup_pipe = -1; 1249 pid = getpid(); 1250 if (rexec_flag) { 1251 send_rexec_state(config_s[0], 1252 &cfg); 1253 close(config_s[0]); 1254 } 1255 break; 1256 } 1257 1258 /* 1259 * Normal production daemon. Fork, and have 1260 * the child process the connection. The 1261 * parent continues listening. 1262 */ 1263 platform_pre_fork(); 1264 if ((pid = fork()) == 0) { 1265 /* 1266 * Child. Close the listening and 1267 * max_startup sockets. Start using 1268 * the accepted socket. Reinitialize 1269 * logging (since our pid has changed). 1270 * We break out of the loop to handle 1271 * the connection. 1272 */ 1273 platform_post_fork_child(); 1274 startup_pipe = startup_p[1]; 1275 close_startup_pipes(); 1276 close_listen_socks(); 1277 *sock_in = *newsock; 1278 *sock_out = *newsock; 1279 log_init(__progname, 1280 options.log_level, 1281 options.log_facility, 1282 log_stderr); 1283 if (rexec_flag) 1284 close(config_s[0]); 1285 break; 1286 } 1287 1288 /* Parent. Stay in the loop. */ 1289 platform_post_fork_parent(pid); 1290 if (pid < 0) 1291 error("fork: %.100s", strerror(errno)); 1292 else 1293 debug("Forked child %ld.", (long)pid); 1294 1295 close(startup_p[1]); 1296 1297 if (rexec_flag) { 1298 send_rexec_state(config_s[0], &cfg); 1299 close(config_s[0]); 1300 close(config_s[1]); 1301 } 1302 1303 /* 1304 * Mark that the key has been used (it 1305 * was "given" to the child). 1306 */ 1307 if ((options.protocol & SSH_PROTO_1) && 1308 key_used == 0) { 1309 /* Schedule server key regeneration alarm. */ 1310 signal(SIGALRM, key_regeneration_alarm); 1311 alarm(options.key_regeneration_time); 1312 key_used = 1; 1313 } 1314 1315 close(*newsock); 1316 1317 /* 1318 * Ensure that our random state differs 1319 * from that of the child 1320 */ 1321 arc4random_stir(); 1322 } 1323 1324 /* child process check (or debug mode) */ 1325 if (num_listen_socks < 0) 1326 break; 1327 } 1328 } 1329 1330 1331 /* 1332 * Main program for the daemon. 1333 */ 1334 int 1335 main(int ac, char **av) 1336 { 1337 extern char *optarg; 1338 extern int optind; 1339 int opt, i, j, on = 1; 1340 int sock_in = -1, sock_out = -1, newsock = -1; 1341 const char *remote_ip; 1342 int remote_port; 1343 char *line; 1344 int config_s[2] = { -1 , -1 }; 1345 u_int64_t ibytes, obytes; 1346 mode_t new_umask; 1347 Key *key; 1348 Authctxt *authctxt; 1349 struct connection_info *connection_info = get_connection_info(0, 0); 1350 1351 #ifdef HAVE_SECUREWARE 1352 (void)set_auth_parameters(ac, av); 1353 #endif 1354 __progname = ssh_get_progname(av[0]); 1355 1356 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1357 saved_argc = ac; 1358 rexec_argc = ac; 1359 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1360 for (i = 0; i < ac; i++) 1361 saved_argv[i] = xstrdup(av[i]); 1362 saved_argv[i] = NULL; 1363 1364 #ifndef HAVE_SETPROCTITLE 1365 /* Prepare for later setproctitle emulation */ 1366 compat_init_setproctitle(ac, av); 1367 av = saved_argv; 1368 #endif 1369 1370 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1371 debug("setgroups(): %.200s", strerror(errno)); 1372 1373 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1374 sanitise_stdfd(); 1375 1376 /* Initialize configuration options to their default values. */ 1377 initialize_server_options(&options); 1378 1379 /* Parse command-line arguments. */ 1380 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) { 1381 switch (opt) { 1382 case '4': 1383 options.address_family = AF_INET; 1384 break; 1385 case '6': 1386 options.address_family = AF_INET6; 1387 break; 1388 case 'f': 1389 config_file_name = optarg; 1390 break; 1391 case 'c': 1392 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1393 fprintf(stderr, "too many host certificates.\n"); 1394 exit(1); 1395 } 1396 options.host_cert_files[options.num_host_cert_files++] = 1397 derelativise_path(optarg); 1398 break; 1399 case 'd': 1400 if (debug_flag == 0) { 1401 debug_flag = 1; 1402 options.log_level = SYSLOG_LEVEL_DEBUG1; 1403 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1404 options.log_level++; 1405 break; 1406 case 'D': 1407 no_daemon_flag = 1; 1408 break; 1409 case 'e': 1410 log_stderr = 1; 1411 break; 1412 case 'i': 1413 inetd_flag = 1; 1414 break; 1415 case 'r': 1416 rexec_flag = 0; 1417 break; 1418 case 'R': 1419 rexeced_flag = 1; 1420 inetd_flag = 1; 1421 break; 1422 case 'Q': 1423 /* ignored */ 1424 break; 1425 case 'q': 1426 options.log_level = SYSLOG_LEVEL_QUIET; 1427 break; 1428 case 'b': 1429 options.server_key_bits = (int)strtonum(optarg, 256, 1430 32768, NULL); 1431 break; 1432 case 'p': 1433 options.ports_from_cmdline = 1; 1434 if (options.num_ports >= MAX_PORTS) { 1435 fprintf(stderr, "too many ports.\n"); 1436 exit(1); 1437 } 1438 options.ports[options.num_ports++] = a2port(optarg); 1439 if (options.ports[options.num_ports-1] <= 0) { 1440 fprintf(stderr, "Bad port number.\n"); 1441 exit(1); 1442 } 1443 break; 1444 case 'g': 1445 if ((options.login_grace_time = convtime(optarg)) == -1) { 1446 fprintf(stderr, "Invalid login grace time.\n"); 1447 exit(1); 1448 } 1449 break; 1450 case 'k': 1451 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1452 fprintf(stderr, "Invalid key regeneration interval.\n"); 1453 exit(1); 1454 } 1455 break; 1456 case 'h': 1457 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1458 fprintf(stderr, "too many host keys.\n"); 1459 exit(1); 1460 } 1461 options.host_key_files[options.num_host_key_files++] = 1462 derelativise_path(optarg); 1463 break; 1464 case 't': 1465 test_flag = 1; 1466 break; 1467 case 'T': 1468 test_flag = 2; 1469 break; 1470 case 'C': 1471 if (parse_server_match_testspec(connection_info, 1472 optarg) == -1) 1473 exit(1); 1474 break; 1475 case 'u': 1476 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1477 if (utmp_len > MAXHOSTNAMELEN) { 1478 fprintf(stderr, "Invalid utmp length.\n"); 1479 exit(1); 1480 } 1481 break; 1482 case 'o': 1483 line = xstrdup(optarg); 1484 if (process_server_config_line(&options, line, 1485 "command-line", 0, NULL, NULL) != 0) 1486 exit(1); 1487 xfree(line); 1488 break; 1489 case '?': 1490 default: 1491 usage(); 1492 break; 1493 } 1494 } 1495 if (rexeced_flag || inetd_flag) 1496 rexec_flag = 0; 1497 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1498 fatal("sshd re-exec requires execution with an absolute path"); 1499 if (rexeced_flag) 1500 closefrom(REEXEC_MIN_FREE_FD); 1501 else 1502 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1503 1504 OpenSSL_add_all_algorithms(); 1505 1506 /* 1507 * Force logging to stderr until we have loaded the private host 1508 * key (unless started from inetd) 1509 */ 1510 log_init(__progname, 1511 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1512 SYSLOG_LEVEL_INFO : options.log_level, 1513 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1514 SYSLOG_FACILITY_AUTH : options.log_facility, 1515 log_stderr || !inetd_flag); 1516 1517 /* 1518 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1519 * root's environment 1520 */ 1521 if (getenv("KRB5CCNAME") != NULL) 1522 (void) unsetenv("KRB5CCNAME"); 1523 1524 #ifdef _UNICOS 1525 /* Cray can define user privs drop all privs now! 1526 * Not needed on PRIV_SU systems! 1527 */ 1528 drop_cray_privs(); 1529 #endif 1530 1531 sensitive_data.server_key = NULL; 1532 sensitive_data.ssh1_host_key = NULL; 1533 sensitive_data.have_ssh1_key = 0; 1534 sensitive_data.have_ssh2_key = 0; 1535 1536 /* 1537 * If we're doing an extended config test, make sure we have all of 1538 * the parameters we need. If we're not doing an extended test, 1539 * do not silently ignore connection test params. 1540 */ 1541 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0) 1542 fatal("user, host and addr are all required when testing " 1543 "Match configs"); 1544 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0) 1545 fatal("Config test connection parameter (-C) provided without " 1546 "test mode (-T)"); 1547 1548 /* Fetch our configuration */ 1549 buffer_init(&cfg); 1550 if (rexeced_flag) 1551 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1552 else 1553 load_server_config(config_file_name, &cfg); 1554 1555 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1556 &cfg, NULL); 1557 1558 seed_rng(); 1559 1560 /* Fill in default values for those options not explicitly set. */ 1561 fill_default_server_options(&options); 1562 1563 /* challenge-response is implemented via keyboard interactive */ 1564 if (options.challenge_response_authentication) 1565 options.kbd_interactive_authentication = 1; 1566 1567 /* set default channel AF */ 1568 channel_set_af(options.address_family); 1569 1570 /* Check that there are no remaining arguments. */ 1571 if (optind < ac) { 1572 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1573 exit(1); 1574 } 1575 1576 debug("sshd version %.100s", SSH_RELEASE); 1577 1578 /* Store privilege separation user for later use if required. */ 1579 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1580 if (use_privsep || options.kerberos_authentication) 1581 fatal("Privilege separation user %s does not exist", 1582 SSH_PRIVSEP_USER); 1583 } else { 1584 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd)); 1585 privsep_pw = pwcopy(privsep_pw); 1586 xfree(privsep_pw->pw_passwd); 1587 privsep_pw->pw_passwd = xstrdup("*"); 1588 } 1589 endpwent(); 1590 1591 /* load private host keys */ 1592 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1593 sizeof(Key *)); 1594 for (i = 0; i < options.num_host_key_files; i++) 1595 sensitive_data.host_keys[i] = NULL; 1596 1597 for (i = 0; i < options.num_host_key_files; i++) { 1598 key = key_load_private(options.host_key_files[i], "", NULL); 1599 if (key && blacklisted_key(key)) { 1600 char *fp; 1601 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX); 1602 if (options.permit_blacklisted_keys) 1603 error("Host key %s blacklisted (see " 1604 "ssh-vulnkey(1)); continuing anyway", fp); 1605 else 1606 error("Host key %s blacklisted (see " 1607 "ssh-vulnkey(1))", fp); 1608 xfree(fp); 1609 if (!options.permit_blacklisted_keys) { 1610 sensitive_data.host_keys[i] = NULL; 1611 continue; 1612 } 1613 } 1614 sensitive_data.host_keys[i] = key; 1615 if (key == NULL) { 1616 error("Could not load host key: %s", 1617 options.host_key_files[i]); 1618 sensitive_data.host_keys[i] = NULL; 1619 continue; 1620 } 1621 switch (key->type) { 1622 case KEY_RSA1: 1623 sensitive_data.ssh1_host_key = key; 1624 sensitive_data.have_ssh1_key = 1; 1625 break; 1626 case KEY_RSA: 1627 case KEY_DSA: 1628 case KEY_ECDSA: 1629 sensitive_data.have_ssh2_key = 1; 1630 break; 1631 } 1632 debug("private host key: #%d type %d %s", i, key->type, 1633 key_type(key)); 1634 } 1635 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1636 logit("Disabling protocol version 1. Could not load host key"); 1637 options.protocol &= ~SSH_PROTO_1; 1638 } 1639 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1640 logit("Disabling protocol version 2. Could not load host key"); 1641 options.protocol &= ~SSH_PROTO_2; 1642 } 1643 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1644 logit("sshd: no hostkeys available -- exiting."); 1645 exit(1); 1646 } 1647 1648 /* 1649 * Load certificates. They are stored in an array at identical 1650 * indices to the public keys that they relate to. 1651 */ 1652 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1653 sizeof(Key *)); 1654 for (i = 0; i < options.num_host_key_files; i++) 1655 sensitive_data.host_certificates[i] = NULL; 1656 1657 for (i = 0; i < options.num_host_cert_files; i++) { 1658 key = key_load_public(options.host_cert_files[i], NULL); 1659 if (key == NULL) { 1660 error("Could not load host certificate: %s", 1661 options.host_cert_files[i]); 1662 continue; 1663 } 1664 if (!key_is_cert(key)) { 1665 error("Certificate file is not a certificate: %s", 1666 options.host_cert_files[i]); 1667 key_free(key); 1668 continue; 1669 } 1670 /* Find matching private key */ 1671 for (j = 0; j < options.num_host_key_files; j++) { 1672 if (key_equal_public(key, 1673 sensitive_data.host_keys[j])) { 1674 sensitive_data.host_certificates[j] = key; 1675 break; 1676 } 1677 } 1678 if (j >= options.num_host_key_files) { 1679 error("No matching private key for certificate: %s", 1680 options.host_cert_files[i]); 1681 key_free(key); 1682 continue; 1683 } 1684 sensitive_data.host_certificates[j] = key; 1685 debug("host certificate: #%d type %d %s", j, key->type, 1686 key_type(key)); 1687 } 1688 /* Check certain values for sanity. */ 1689 if (options.protocol & SSH_PROTO_1) { 1690 if (options.server_key_bits < 512 || 1691 options.server_key_bits > 32768) { 1692 fprintf(stderr, "Bad server key size.\n"); 1693 exit(1); 1694 } 1695 /* 1696 * Check that server and host key lengths differ sufficiently. This 1697 * is necessary to make double encryption work with rsaref. Oh, I 1698 * hate software patents. I dont know if this can go? Niels 1699 */ 1700 if (options.server_key_bits > 1701 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1702 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1703 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1704 SSH_KEY_BITS_RESERVED) { 1705 options.server_key_bits = 1706 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1707 SSH_KEY_BITS_RESERVED; 1708 debug("Forcing server key to %d bits to make it differ from host key.", 1709 options.server_key_bits); 1710 } 1711 } 1712 1713 if (use_privsep) { 1714 struct stat st; 1715 1716 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1717 (S_ISDIR(st.st_mode) == 0)) 1718 fatal("Missing privilege separation directory: %s", 1719 _PATH_PRIVSEP_CHROOT_DIR); 1720 1721 #ifdef HAVE_CYGWIN 1722 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1723 (st.st_uid != getuid () || 1724 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1725 #else 1726 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1727 #endif 1728 fatal("%s must be owned by root and not group or " 1729 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1730 } 1731 1732 if (test_flag > 1) { 1733 if (server_match_spec_complete(connection_info) == 1) 1734 parse_server_match_config(&options, connection_info); 1735 dump_config(&options); 1736 } 1737 1738 /* Configuration looks good, so exit if in test mode. */ 1739 if (test_flag) 1740 exit(0); 1741 1742 /* 1743 * Clear out any supplemental groups we may have inherited. This 1744 * prevents inadvertent creation of files with bad modes (in the 1745 * portable version at least, it's certainly possible for PAM 1746 * to create a file, and we can't control the code in every 1747 * module which might be used). 1748 */ 1749 if (setgroups(0, NULL) < 0) 1750 debug("setgroups() failed: %.200s", strerror(errno)); 1751 1752 if (rexec_flag) { 1753 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1754 for (i = 0; i < rexec_argc; i++) { 1755 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1756 rexec_argv[i] = saved_argv[i]; 1757 } 1758 rexec_argv[rexec_argc] = "-R"; 1759 rexec_argv[rexec_argc + 1] = NULL; 1760 } 1761 1762 /* Ensure that umask disallows at least group and world write */ 1763 new_umask = umask(0077) | 0022; 1764 (void) umask(new_umask); 1765 1766 /* Initialize the log (it is reinitialized below in case we forked). */ 1767 if (debug_flag && (!inetd_flag || rexeced_flag)) 1768 log_stderr = 1; 1769 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1770 1771 /* 1772 * If not in debugging mode, and not started from inetd, disconnect 1773 * from the controlling terminal, and fork. The original process 1774 * exits. 1775 */ 1776 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1777 #ifdef TIOCNOTTY 1778 int fd; 1779 #endif /* TIOCNOTTY */ 1780 if (daemon(0, 0) < 0) 1781 fatal("daemon() failed: %.200s", strerror(errno)); 1782 1783 /* Disconnect from the controlling tty. */ 1784 #ifdef TIOCNOTTY 1785 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1786 if (fd >= 0) { 1787 (void) ioctl(fd, TIOCNOTTY, NULL); 1788 close(fd); 1789 } 1790 #endif /* TIOCNOTTY */ 1791 } 1792 /* Reinitialize the log (because of the fork above). */ 1793 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1794 1795 /* Initialize the random number generator. */ 1796 arc4random_stir(); 1797 1798 /* Chdir to the root directory so that the current disk can be 1799 unmounted if desired. */ 1800 chdir("/"); 1801 1802 /* ignore SIGPIPE */ 1803 signal(SIGPIPE, SIG_IGN); 1804 1805 /* Get a connection, either from inetd or a listening TCP socket */ 1806 if (inetd_flag) { 1807 server_accept_inetd(&sock_in, &sock_out); 1808 } else { 1809 platform_pre_listen(); 1810 server_listen(); 1811 1812 if (options.protocol & SSH_PROTO_1) 1813 generate_ephemeral_server_key(); 1814 1815 signal(SIGHUP, sighup_handler); 1816 signal(SIGCHLD, main_sigchld_handler); 1817 signal(SIGTERM, sigterm_handler); 1818 signal(SIGQUIT, sigterm_handler); 1819 1820 /* 1821 * Write out the pid file after the sigterm handler 1822 * is setup and the listen sockets are bound 1823 */ 1824 if (!debug_flag) { 1825 FILE *f = fopen(options.pid_file, "w"); 1826 1827 if (f == NULL) { 1828 error("Couldn't create pid file \"%s\": %s", 1829 options.pid_file, strerror(errno)); 1830 } else { 1831 fprintf(f, "%ld\n", (long) getpid()); 1832 fclose(f); 1833 } 1834 } 1835 1836 /* Accept a connection and return in a forked child */ 1837 server_accept_loop(&sock_in, &sock_out, 1838 &newsock, config_s); 1839 } 1840 1841 /* This is the child processing a new connection. */ 1842 setproctitle("%s", "[accepted]"); 1843 1844 /* 1845 * Initialize the resolver. This may not happen automatically 1846 * before privsep chroot(). 1847 */ 1848 if ((_res.options & RES_INIT) == 0) { 1849 debug("res_init()"); 1850 res_init(); 1851 } 1852 1853 /* 1854 * Create a new session and process group since the 4.4BSD 1855 * setlogin() affects the entire process group. We don't 1856 * want the child to be able to affect the parent. 1857 */ 1858 #if !defined(SSHD_ACQUIRES_CTTY) 1859 /* 1860 * If setsid is called, on some platforms sshd will later acquire a 1861 * controlling terminal which will result in "could not set 1862 * controlling tty" errors. 1863 */ 1864 if (!debug_flag && !inetd_flag && setsid() < 0) 1865 error("setsid: %.100s", strerror(errno)); 1866 #endif 1867 1868 if (rexec_flag) { 1869 int fd; 1870 1871 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1872 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1873 dup2(newsock, STDIN_FILENO); 1874 dup2(STDIN_FILENO, STDOUT_FILENO); 1875 if (startup_pipe == -1) 1876 close(REEXEC_STARTUP_PIPE_FD); 1877 else 1878 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1879 1880 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1881 close(config_s[1]); 1882 if (startup_pipe != -1) 1883 close(startup_pipe); 1884 1885 execv(rexec_argv[0], rexec_argv); 1886 1887 /* Reexec has failed, fall back and continue */ 1888 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1889 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1890 log_init(__progname, options.log_level, 1891 options.log_facility, log_stderr); 1892 1893 /* Clean up fds */ 1894 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1895 close(config_s[1]); 1896 close(REEXEC_CONFIG_PASS_FD); 1897 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1898 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1899 dup2(fd, STDIN_FILENO); 1900 dup2(fd, STDOUT_FILENO); 1901 if (fd > STDERR_FILENO) 1902 close(fd); 1903 } 1904 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1905 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1906 } 1907 1908 /* Executed child processes don't need these. */ 1909 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1910 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1911 1912 /* 1913 * Disable the key regeneration alarm. We will not regenerate the 1914 * key since we are no longer in a position to give it to anyone. We 1915 * will not restart on SIGHUP since it no longer makes sense. 1916 */ 1917 alarm(0); 1918 signal(SIGALRM, SIG_DFL); 1919 signal(SIGHUP, SIG_DFL); 1920 signal(SIGTERM, SIG_DFL); 1921 signal(SIGQUIT, SIG_DFL); 1922 signal(SIGCHLD, SIG_DFL); 1923 signal(SIGINT, SIG_DFL); 1924 1925 /* 1926 * Register our connection. This turns encryption off because we do 1927 * not have a key. 1928 */ 1929 packet_set_connection(sock_in, sock_out); 1930 packet_set_server(); 1931 1932 /* Set SO_KEEPALIVE if requested. */ 1933 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1934 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1935 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1936 1937 if ((remote_port = get_remote_port()) < 0) { 1938 debug("get_remote_port failed"); 1939 cleanup_exit(255); 1940 } 1941 1942 /* 1943 * We use get_canonical_hostname with usedns = 0 instead of 1944 * get_remote_ipaddr here so IP options will be checked. 1945 */ 1946 (void) get_canonical_hostname(0); 1947 /* 1948 * The rest of the code depends on the fact that 1949 * get_remote_ipaddr() caches the remote ip, even if 1950 * the socket goes away. 1951 */ 1952 remote_ip = get_remote_ipaddr(); 1953 1954 #ifdef SSH_AUDIT_EVENTS 1955 audit_connection_from(remote_ip, remote_port); 1956 #endif 1957 #ifdef LIBWRAP 1958 allow_severity = options.log_facility|LOG_INFO; 1959 deny_severity = options.log_facility|LOG_WARNING; 1960 /* Check whether logins are denied from this host. */ 1961 if (packet_connection_is_on_socket()) { 1962 struct request_info req; 1963 1964 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 1965 fromhost(&req); 1966 1967 if (!hosts_access(&req)) { 1968 debug("Connection refused by tcp wrapper"); 1969 refuse(&req); 1970 /* NOTREACHED */ 1971 fatal("libwrap refuse returns"); 1972 } 1973 } 1974 #endif /* LIBWRAP */ 1975 1976 /* Log the connection. */ 1977 verbose("Connection from %.500s port %d", remote_ip, remote_port); 1978 1979 /* set the HPN options for the child */ 1980 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size); 1981 1982 /* 1983 * We don't want to listen forever unless the other side 1984 * successfully authenticates itself. So we set up an alarm which is 1985 * cleared after successful authentication. A limit of zero 1986 * indicates no limit. Note that we don't set the alarm in debugging 1987 * mode; it is just annoying to have the server exit just when you 1988 * are about to discover the bug. 1989 */ 1990 signal(SIGALRM, grace_alarm_handler); 1991 if (!debug_flag) 1992 alarm(options.login_grace_time); 1993 1994 sshd_exchange_identification(sock_in, sock_out); 1995 1996 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 1997 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 1998 generate_ephemeral_server_key(); 1999 2000 packet_set_nonblocking(); 2001 2002 /* allocate authentication context */ 2003 authctxt = xcalloc(1, sizeof(*authctxt)); 2004 2005 authctxt->loginmsg = &loginmsg; 2006 2007 /* XXX global for cleanup, access from other modules */ 2008 the_authctxt = authctxt; 2009 2010 /* prepare buffer to collect messages to display to user after login */ 2011 buffer_init(&loginmsg); 2012 auth_debug_reset(); 2013 2014 if (use_privsep) 2015 if (privsep_preauth(authctxt) == 1) 2016 goto authenticated; 2017 2018 /* perform the key exchange */ 2019 /* authenticate user and start session */ 2020 if (compat20) { 2021 do_ssh2_kex(); 2022 do_authentication2(authctxt); 2023 } else { 2024 do_ssh1_kex(); 2025 do_authentication(authctxt); 2026 } 2027 /* 2028 * If we use privilege separation, the unprivileged child transfers 2029 * the current keystate and exits 2030 */ 2031 if (use_privsep) { 2032 mm_send_keystate(pmonitor); 2033 exit(0); 2034 } 2035 2036 authenticated: 2037 /* 2038 * Cancel the alarm we set to limit the time taken for 2039 * authentication. 2040 */ 2041 alarm(0); 2042 signal(SIGALRM, SIG_DFL); 2043 authctxt->authenticated = 1; 2044 if (startup_pipe != -1) { 2045 close(startup_pipe); 2046 startup_pipe = -1; 2047 } 2048 2049 #ifdef SSH_AUDIT_EVENTS 2050 audit_event(SSH_AUTH_SUCCESS); 2051 #endif 2052 2053 #ifdef GSSAPI 2054 if (options.gss_authentication) { 2055 temporarily_use_uid(authctxt->pw); 2056 ssh_gssapi_storecreds(); 2057 restore_uid(); 2058 } 2059 #endif 2060 #ifdef USE_PAM 2061 if (options.use_pam) { 2062 do_pam_setcred(1); 2063 do_pam_session(); 2064 } 2065 #endif 2066 2067 /* 2068 * In privilege separation, we fork another child and prepare 2069 * file descriptor passing. 2070 */ 2071 if (use_privsep) { 2072 privsep_postauth(authctxt); 2073 /* the monitor process [priv] will not return */ 2074 if (!compat20) 2075 destroy_sensitive_data(); 2076 } 2077 2078 packet_set_timeout(options.client_alive_interval, 2079 options.client_alive_count_max); 2080 2081 /* Start session. */ 2082 do_authenticated(authctxt); 2083 2084 /* The connection has been terminated. */ 2085 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 2086 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 2087 verbose("Transferred: sent %llu, received %llu bytes", 2088 (unsigned long long)obytes, (unsigned long long)ibytes); 2089 2090 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2091 2092 #ifdef USE_PAM 2093 if (options.use_pam) 2094 finish_pam(); 2095 #endif /* USE_PAM */ 2096 2097 #ifdef SSH_AUDIT_EVENTS 2098 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2099 #endif 2100 2101 packet_close(); 2102 2103 if (use_privsep) 2104 mm_terminate(); 2105 2106 exit(0); 2107 } 2108 2109 /* 2110 * Decrypt session_key_int using our private server key and private host key 2111 * (key with larger modulus first). 2112 */ 2113 int 2114 ssh1_session_key(BIGNUM *session_key_int) 2115 { 2116 int rsafail = 0; 2117 2118 if (BN_cmp(sensitive_data.server_key->rsa->n, 2119 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2120 /* Server key has bigger modulus. */ 2121 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2122 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2123 SSH_KEY_BITS_RESERVED) { 2124 fatal("do_connection: %s: " 2125 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2126 get_remote_ipaddr(), 2127 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 } 2131 if (rsa_private_decrypt(session_key_int, session_key_int, 2132 sensitive_data.server_key->rsa) <= 0) 2133 rsafail++; 2134 if (rsa_private_decrypt(session_key_int, session_key_int, 2135 sensitive_data.ssh1_host_key->rsa) <= 0) 2136 rsafail++; 2137 } else { 2138 /* Host key has bigger modulus (or they are equal). */ 2139 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2140 BN_num_bits(sensitive_data.server_key->rsa->n) + 2141 SSH_KEY_BITS_RESERVED) { 2142 fatal("do_connection: %s: " 2143 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2144 get_remote_ipaddr(), 2145 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 } 2149 if (rsa_private_decrypt(session_key_int, session_key_int, 2150 sensitive_data.ssh1_host_key->rsa) < 0) 2151 rsafail++; 2152 if (rsa_private_decrypt(session_key_int, session_key_int, 2153 sensitive_data.server_key->rsa) < 0) 2154 rsafail++; 2155 } 2156 return (rsafail); 2157 } 2158 /* 2159 * SSH1 key exchange 2160 */ 2161 static void 2162 do_ssh1_kex(void) 2163 { 2164 int i, len; 2165 int rsafail = 0; 2166 BIGNUM *session_key_int; 2167 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2168 u_char cookie[8]; 2169 u_int cipher_type, auth_mask, protocol_flags; 2170 2171 /* 2172 * Generate check bytes that the client must send back in the user 2173 * packet in order for it to be accepted; this is used to defy ip 2174 * spoofing attacks. Note that this only works against somebody 2175 * doing IP spoofing from a remote machine; any machine on the local 2176 * network can still see outgoing packets and catch the random 2177 * cookie. This only affects rhosts authentication, and this is one 2178 * of the reasons why it is inherently insecure. 2179 */ 2180 arc4random_buf(cookie, sizeof(cookie)); 2181 2182 /* 2183 * Send our public key. We include in the packet 64 bits of random 2184 * data that must be matched in the reply in order to prevent IP 2185 * spoofing. 2186 */ 2187 packet_start(SSH_SMSG_PUBLIC_KEY); 2188 for (i = 0; i < 8; i++) 2189 packet_put_char(cookie[i]); 2190 2191 /* Store our public server RSA key. */ 2192 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2193 packet_put_bignum(sensitive_data.server_key->rsa->e); 2194 packet_put_bignum(sensitive_data.server_key->rsa->n); 2195 2196 /* Store our public host RSA key. */ 2197 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2198 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2199 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2200 2201 /* Put protocol flags. */ 2202 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2203 2204 /* Declare which ciphers we support. */ 2205 packet_put_int(cipher_mask_ssh1(0)); 2206 2207 /* Declare supported authentication types. */ 2208 auth_mask = 0; 2209 if (options.rhosts_rsa_authentication) 2210 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2211 if (options.rsa_authentication) 2212 auth_mask |= 1 << SSH_AUTH_RSA; 2213 if (options.challenge_response_authentication == 1) 2214 auth_mask |= 1 << SSH_AUTH_TIS; 2215 if (options.password_authentication) 2216 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2217 packet_put_int(auth_mask); 2218 2219 /* Send the packet and wait for it to be sent. */ 2220 packet_send(); 2221 packet_write_wait(); 2222 2223 debug("Sent %d bit server key and %d bit host key.", 2224 BN_num_bits(sensitive_data.server_key->rsa->n), 2225 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2226 2227 /* Read clients reply (cipher type and session key). */ 2228 packet_read_expect(SSH_CMSG_SESSION_KEY); 2229 2230 /* Get cipher type and check whether we accept this. */ 2231 cipher_type = packet_get_char(); 2232 2233 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2234 packet_disconnect("Warning: client selects unsupported cipher."); 2235 2236 /* Get check bytes from the packet. These must match those we 2237 sent earlier with the public key packet. */ 2238 for (i = 0; i < 8; i++) 2239 if (cookie[i] != packet_get_char()) 2240 packet_disconnect("IP Spoofing check bytes do not match."); 2241 2242 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2243 2244 /* Get the encrypted integer. */ 2245 if ((session_key_int = BN_new()) == NULL) 2246 fatal("do_ssh1_kex: BN_new failed"); 2247 packet_get_bignum(session_key_int); 2248 2249 protocol_flags = packet_get_int(); 2250 packet_set_protocol_flags(protocol_flags); 2251 packet_check_eom(); 2252 2253 /* Decrypt session_key_int using host/server keys */ 2254 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2255 2256 /* 2257 * Extract session key from the decrypted integer. The key is in the 2258 * least significant 256 bits of the integer; the first byte of the 2259 * key is in the highest bits. 2260 */ 2261 if (!rsafail) { 2262 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2263 len = BN_num_bytes(session_key_int); 2264 if (len < 0 || (u_int)len > sizeof(session_key)) { 2265 error("do_ssh1_kex: bad session key len from %s: " 2266 "session_key_int %d > sizeof(session_key) %lu", 2267 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2268 rsafail++; 2269 } else { 2270 memset(session_key, 0, sizeof(session_key)); 2271 BN_bn2bin(session_key_int, 2272 session_key + sizeof(session_key) - len); 2273 2274 derive_ssh1_session_id( 2275 sensitive_data.ssh1_host_key->rsa->n, 2276 sensitive_data.server_key->rsa->n, 2277 cookie, session_id); 2278 /* 2279 * Xor the first 16 bytes of the session key with the 2280 * session id. 2281 */ 2282 for (i = 0; i < 16; i++) 2283 session_key[i] ^= session_id[i]; 2284 } 2285 } 2286 if (rsafail) { 2287 int bytes = BN_num_bytes(session_key_int); 2288 u_char *buf = xmalloc(bytes); 2289 MD5_CTX md; 2290 2291 logit("do_connection: generating a fake encryption key"); 2292 BN_bn2bin(session_key_int, buf); 2293 MD5_Init(&md); 2294 MD5_Update(&md, buf, bytes); 2295 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2296 MD5_Final(session_key, &md); 2297 MD5_Init(&md); 2298 MD5_Update(&md, session_key, 16); 2299 MD5_Update(&md, buf, bytes); 2300 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2301 MD5_Final(session_key + 16, &md); 2302 memset(buf, 0, bytes); 2303 xfree(buf); 2304 for (i = 0; i < 16; i++) 2305 session_id[i] = session_key[i] ^ session_key[i + 16]; 2306 } 2307 /* Destroy the private and public keys. No longer. */ 2308 destroy_sensitive_data(); 2309 2310 if (use_privsep) 2311 mm_ssh1_session_id(session_id); 2312 2313 /* Destroy the decrypted integer. It is no longer needed. */ 2314 BN_clear_free(session_key_int); 2315 2316 /* Set the session key. From this on all communications will be encrypted. */ 2317 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2318 2319 /* Destroy our copy of the session key. It is no longer needed. */ 2320 memset(session_key, 0, sizeof(session_key)); 2321 2322 debug("Received session key; encryption turned on."); 2323 2324 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2325 packet_start(SSH_SMSG_SUCCESS); 2326 packet_send(); 2327 packet_write_wait(); 2328 } 2329 2330 /* 2331 * SSH2 key exchange: diffie-hellman-group1-sha1 2332 */ 2333 static void 2334 do_ssh2_kex(void) 2335 { 2336 Kex *kex; 2337 2338 myflag++; 2339 debug ("MYFLAG IS %d", myflag); 2340 if (options.ciphers != NULL) { 2341 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2342 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2343 } else if (options.none_enabled == 1) { 2344 debug ("WARNING: None cipher enabled"); 2345 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2346 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE; 2347 } 2348 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2349 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2350 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2351 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2352 2353 if (options.macs != NULL) { 2354 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2355 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2356 } 2357 if (options.compression == COMP_NONE) { 2358 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2359 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2360 } else if (options.compression == COMP_DELAYED) { 2361 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2362 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2363 } 2364 if (options.kex_algorithms != NULL) 2365 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 2366 2367 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); 2368 2369 /* start key exchange */ 2370 kex = kex_setup(myproposal); 2371 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2372 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2373 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2374 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2375 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2376 kex->server = 1; 2377 kex->client_version_string=client_version_string; 2378 kex->server_version_string=server_version_string; 2379 kex->load_host_public_key=&get_hostkey_public_by_type; 2380 kex->load_host_private_key=&get_hostkey_private_by_type; 2381 kex->host_key_index=&get_hostkey_index; 2382 2383 xxx_kex = kex; 2384 2385 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2386 2387 session_id2 = kex->session_id; 2388 session_id2_len = kex->session_id_len; 2389 2390 #ifdef DEBUG_KEXDH 2391 /* send 1st encrypted/maced/compressed message */ 2392 packet_start(SSH2_MSG_IGNORE); 2393 packet_put_cstring("markus"); 2394 packet_send(); 2395 packet_write_wait(); 2396 #endif 2397 debug("KEX done"); 2398 } 2399 2400 /* server specific fatal cleanup */ 2401 void 2402 cleanup_exit(int i) 2403 { 2404 if (the_authctxt) { 2405 do_cleanup(the_authctxt); 2406 if (use_privsep && privsep_is_preauth && pmonitor->m_pid > 1) { 2407 debug("Killing privsep child %d", pmonitor->m_pid); 2408 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2409 errno != ESRCH) 2410 error("%s: kill(%d): %s", __func__, 2411 pmonitor->m_pid, strerror(errno)); 2412 } 2413 } 2414 #ifdef SSH_AUDIT_EVENTS 2415 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2416 if (!use_privsep || mm_is_monitor()) 2417 audit_event(SSH_CONNECTION_ABANDON); 2418 #endif 2419 _exit(i); 2420 } 2421