1 /* $OpenBSD: sshd.c,v 1.385 2011/06/23 09:34:13 djm Exp $ */ 2 /* $FreeBSD$ */ 3 /* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * This program is the ssh daemon. It listens for connections from clients, 8 * and performs authentication, executes use commands or shell, and forwards 9 * information to/from the application to the user client over an encrypted 10 * connection. This can also handle forwarding of X11, TCP/IP, and 11 * authentication agent connections. 12 * 13 * As far as I am concerned, the code I have written for this software 14 * can be used freely for any purpose. Any derived versions of this 15 * software must be clearly marked as such, and if the derived work is 16 * incompatible with the protocol description in the RFC file, it must be 17 * called by a name other than "ssh" or "Secure Shell". 18 * 19 * SSH2 implementation: 20 * Privilege Separation: 21 * 22 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 23 * Copyright (c) 2002 Niels Provos. All rights reserved. 24 * 25 * Redistribution and use in source and binary forms, with or without 26 * modification, are permitted provided that the following conditions 27 * are met: 28 * 1. Redistributions of source code must retain the above copyright 29 * notice, this list of conditions and the following disclaimer. 30 * 2. Redistributions in binary form must reproduce the above copyright 31 * notice, this list of conditions and the following disclaimer in the 32 * documentation and/or other materials provided with the distribution. 33 * 34 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 35 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 36 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 37 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 38 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 39 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 40 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 41 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 42 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 43 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 44 */ 45 46 #include "includes.h" 47 __RCSID("$FreeBSD$"); 48 49 #include <sys/types.h> 50 #include <sys/ioctl.h> 51 #include <sys/mman.h> 52 #include <sys/socket.h> 53 #ifdef HAVE_SYS_STAT_H 54 # include <sys/stat.h> 55 #endif 56 #ifdef HAVE_SYS_TIME_H 57 # include <sys/time.h> 58 #endif 59 #include "openbsd-compat/sys-tree.h" 60 #include "openbsd-compat/sys-queue.h" 61 #include <sys/wait.h> 62 63 #include <errno.h> 64 #include <fcntl.h> 65 #include <netdb.h> 66 #ifdef HAVE_PATHS_H 67 #include <paths.h> 68 #endif 69 #include <grp.h> 70 #include <pwd.h> 71 #include <signal.h> 72 #include <stdarg.h> 73 #include <stdio.h> 74 #include <stdlib.h> 75 #include <string.h> 76 #include <unistd.h> 77 78 #include <openssl/dh.h> 79 #include <openssl/bn.h> 80 #include <openssl/md5.h> 81 #include <openssl/rand.h> 82 #include "openbsd-compat/openssl-compat.h" 83 84 #ifdef HAVE_SECUREWARE 85 #include <sys/security.h> 86 #include <prot.h> 87 #endif 88 89 #ifdef __FreeBSD__ 90 #include <resolv.h> 91 #if defined(GSSAPI) && defined(HAVE_GSSAPI_H) 92 #include <gssapi.h> 93 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H) 94 #include <gssapi/gssapi.h> 95 #endif 96 #endif 97 98 #include "xmalloc.h" 99 #include "ssh.h" 100 #include "ssh1.h" 101 #include "ssh2.h" 102 #include "rsa.h" 103 #include "sshpty.h" 104 #include "packet.h" 105 #include "log.h" 106 #include "buffer.h" 107 #include "servconf.h" 108 #include "uidswap.h" 109 #include "compat.h" 110 #include "cipher.h" 111 #include "key.h" 112 #include "kex.h" 113 #include "dh.h" 114 #include "myproposal.h" 115 #include "authfile.h" 116 #include "pathnames.h" 117 #include "atomicio.h" 118 #include "canohost.h" 119 #include "hostfile.h" 120 #include "auth.h" 121 #include "misc.h" 122 #include "msg.h" 123 #include "dispatch.h" 124 #include "channels.h" 125 #include "session.h" 126 #include "monitor_mm.h" 127 #include "monitor.h" 128 #ifdef GSSAPI 129 #include "ssh-gss.h" 130 #endif 131 #include "monitor_wrap.h" 132 #include "roaming.h" 133 #include "ssh-sandbox.h" 134 #include "version.h" 135 136 #ifdef LIBWRAP 137 #include <tcpd.h> 138 #include <syslog.h> 139 int allow_severity; 140 int deny_severity; 141 #endif /* LIBWRAP */ 142 143 #ifndef O_NOCTTY 144 #define O_NOCTTY 0 145 #endif 146 147 /* Re-exec fds */ 148 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 149 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 150 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 151 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 152 153 extern char *__progname; 154 155 /* Server configuration options. */ 156 ServerOptions options; 157 158 /* Name of the server configuration file. */ 159 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 160 161 /* 162 * Debug mode flag. This can be set on the command line. If debug 163 * mode is enabled, extra debugging output will be sent to the system 164 * log, the daemon will not go to background, and will exit after processing 165 * the first connection. 166 */ 167 int debug_flag = 0; 168 169 /* Flag indicating that the daemon should only test the configuration and keys. */ 170 int test_flag = 0; 171 172 /* Flag indicating that the daemon is being started from inetd. */ 173 int inetd_flag = 0; 174 175 /* Flag indicating that sshd should not detach and become a daemon. */ 176 int no_daemon_flag = 0; 177 178 /* debug goes to stderr unless inetd_flag is set */ 179 int log_stderr = 0; 180 181 /* Saved arguments to main(). */ 182 char **saved_argv; 183 int saved_argc; 184 185 /* re-exec */ 186 int rexeced_flag = 0; 187 int rexec_flag = 1; 188 int rexec_argc = 0; 189 char **rexec_argv; 190 191 /* 192 * The sockets that the server is listening; this is used in the SIGHUP 193 * signal handler. 194 */ 195 #define MAX_LISTEN_SOCKS 16 196 int listen_socks[MAX_LISTEN_SOCKS]; 197 int num_listen_socks = 0; 198 199 /* 200 * the client's version string, passed by sshd2 in compat mode. if != NULL, 201 * sshd will skip the version-number exchange 202 */ 203 char *client_version_string = NULL; 204 char *server_version_string = NULL; 205 206 /* for rekeying XXX fixme */ 207 Kex *xxx_kex; 208 209 /* 210 * Any really sensitive data in the application is contained in this 211 * structure. The idea is that this structure could be locked into memory so 212 * that the pages do not get written into swap. However, there are some 213 * problems. The private key contains BIGNUMs, and we do not (in principle) 214 * have access to the internals of them, and locking just the structure is 215 * not very useful. Currently, memory locking is not implemented. 216 */ 217 struct { 218 Key *server_key; /* ephemeral server key */ 219 Key *ssh1_host_key; /* ssh1 host key */ 220 Key **host_keys; /* all private host keys */ 221 Key **host_certificates; /* all public host certificates */ 222 int have_ssh1_key; 223 int have_ssh2_key; 224 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 225 } sensitive_data; 226 227 /* 228 * Flag indicating whether the RSA server key needs to be regenerated. 229 * Is set in the SIGALRM handler and cleared when the key is regenerated. 230 */ 231 static volatile sig_atomic_t key_do_regen = 0; 232 233 /* This is set to true when a signal is received. */ 234 static volatile sig_atomic_t received_sighup = 0; 235 static volatile sig_atomic_t received_sigterm = 0; 236 237 /* session identifier, used by RSA-auth */ 238 u_char session_id[16]; 239 240 /* same for ssh2 */ 241 u_char *session_id2 = NULL; 242 u_int session_id2_len = 0; 243 244 /* record remote hostname or ip */ 245 u_int utmp_len = MAXHOSTNAMELEN; 246 247 /* options.max_startup sized array of fd ints */ 248 int *startup_pipes = NULL; 249 int startup_pipe; /* in child */ 250 251 /* variables used for privilege separation */ 252 int use_privsep = -1; 253 struct monitor *pmonitor = NULL; 254 255 /* global authentication context */ 256 Authctxt *the_authctxt = NULL; 257 258 /* sshd_config buffer */ 259 Buffer cfg; 260 261 /* message to be displayed after login */ 262 Buffer loginmsg; 263 264 /* Unprivileged user */ 265 struct passwd *privsep_pw = NULL; 266 267 /* Prototypes for various functions defined later in this file. */ 268 void destroy_sensitive_data(void); 269 void demote_sensitive_data(void); 270 271 static void do_ssh1_kex(void); 272 static void do_ssh2_kex(void); 273 274 /* 275 * Close all listening sockets 276 */ 277 static void 278 close_listen_socks(void) 279 { 280 int i; 281 282 for (i = 0; i < num_listen_socks; i++) 283 close(listen_socks[i]); 284 num_listen_socks = -1; 285 } 286 287 static void 288 close_startup_pipes(void) 289 { 290 int i; 291 292 if (startup_pipes) 293 for (i = 0; i < options.max_startups; i++) 294 if (startup_pipes[i] != -1) 295 close(startup_pipes[i]); 296 } 297 298 /* 299 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 300 * the effect is to reread the configuration file (and to regenerate 301 * the server key). 302 */ 303 304 /*ARGSUSED*/ 305 static void 306 sighup_handler(int sig) 307 { 308 int save_errno = errno; 309 310 received_sighup = 1; 311 signal(SIGHUP, sighup_handler); 312 errno = save_errno; 313 } 314 315 /* 316 * Called from the main program after receiving SIGHUP. 317 * Restarts the server. 318 */ 319 static void 320 sighup_restart(void) 321 { 322 logit("Received SIGHUP; restarting."); 323 close_listen_socks(); 324 close_startup_pipes(); 325 alarm(0); /* alarm timer persists across exec */ 326 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 327 execv(saved_argv[0], saved_argv); 328 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 329 strerror(errno)); 330 exit(1); 331 } 332 333 /* 334 * Generic signal handler for terminating signals in the master daemon. 335 */ 336 /*ARGSUSED*/ 337 static void 338 sigterm_handler(int sig) 339 { 340 received_sigterm = sig; 341 } 342 343 /* 344 * SIGCHLD handler. This is called whenever a child dies. This will then 345 * reap any zombies left by exited children. 346 */ 347 /*ARGSUSED*/ 348 static void 349 main_sigchld_handler(int sig) 350 { 351 int save_errno = errno; 352 pid_t pid; 353 int status; 354 355 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 356 (pid < 0 && errno == EINTR)) 357 ; 358 359 signal(SIGCHLD, main_sigchld_handler); 360 errno = save_errno; 361 } 362 363 /* 364 * Signal handler for the alarm after the login grace period has expired. 365 */ 366 /*ARGSUSED*/ 367 static void 368 grace_alarm_handler(int sig) 369 { 370 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 371 kill(pmonitor->m_pid, SIGALRM); 372 373 /* Log error and exit. */ 374 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 375 } 376 377 /* 378 * Signal handler for the key regeneration alarm. Note that this 379 * alarm only occurs in the daemon waiting for connections, and it does not 380 * do anything with the private key or random state before forking. 381 * Thus there should be no concurrency control/asynchronous execution 382 * problems. 383 */ 384 static void 385 generate_ephemeral_server_key(void) 386 { 387 verbose("Generating %s%d bit RSA key.", 388 sensitive_data.server_key ? "new " : "", options.server_key_bits); 389 if (sensitive_data.server_key != NULL) 390 key_free(sensitive_data.server_key); 391 sensitive_data.server_key = key_generate(KEY_RSA1, 392 options.server_key_bits); 393 verbose("RSA key generation complete."); 394 395 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 396 arc4random_stir(); 397 } 398 399 /*ARGSUSED*/ 400 static void 401 key_regeneration_alarm(int sig) 402 { 403 int save_errno = errno; 404 405 signal(SIGALRM, SIG_DFL); 406 errno = save_errno; 407 key_do_regen = 1; 408 } 409 410 static void 411 sshd_exchange_identification(int sock_in, int sock_out) 412 { 413 u_int i; 414 int mismatch; 415 int remote_major, remote_minor; 416 int major, minor; 417 char *s, *newline = "\n"; 418 char buf[256]; /* Must not be larger than remote_version. */ 419 char remote_version[256]; /* Must be at least as big as buf. */ 420 421 if ((options.protocol & SSH_PROTO_1) && 422 (options.protocol & SSH_PROTO_2)) { 423 major = PROTOCOL_MAJOR_1; 424 minor = 99; 425 } else if (options.protocol & SSH_PROTO_2) { 426 major = PROTOCOL_MAJOR_2; 427 minor = PROTOCOL_MINOR_2; 428 newline = "\r\n"; 429 } else { 430 major = PROTOCOL_MAJOR_1; 431 minor = PROTOCOL_MINOR_1; 432 } 433 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor, 434 SSH_RELEASE, newline); 435 server_version_string = xstrdup(buf); 436 437 /* Send our protocol version identification. */ 438 if (roaming_atomicio(vwrite, sock_out, server_version_string, 439 strlen(server_version_string)) 440 != strlen(server_version_string)) { 441 logit("Could not write ident string to %s", get_remote_ipaddr()); 442 cleanup_exit(255); 443 } 444 445 /* Read other sides version identification. */ 446 memset(buf, 0, sizeof(buf)); 447 for (i = 0; i < sizeof(buf) - 1; i++) { 448 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 449 logit("Did not receive identification string from %s", 450 get_remote_ipaddr()); 451 cleanup_exit(255); 452 } 453 if (buf[i] == '\r') { 454 buf[i] = 0; 455 /* Kludge for F-Secure Macintosh < 1.0.2 */ 456 if (i == 12 && 457 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 458 break; 459 continue; 460 } 461 if (buf[i] == '\n') { 462 buf[i] = 0; 463 break; 464 } 465 } 466 buf[sizeof(buf) - 1] = 0; 467 client_version_string = xstrdup(buf); 468 469 /* 470 * Check that the versions match. In future this might accept 471 * several versions and set appropriate flags to handle them. 472 */ 473 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 474 &remote_major, &remote_minor, remote_version) != 3) { 475 s = "Protocol mismatch.\n"; 476 (void) atomicio(vwrite, sock_out, s, strlen(s)); 477 close(sock_in); 478 close(sock_out); 479 logit("Bad protocol version identification '%.100s' from %s", 480 client_version_string, get_remote_ipaddr()); 481 cleanup_exit(255); 482 } 483 debug("Client protocol version %d.%d; client software version %.100s", 484 remote_major, remote_minor, remote_version); 485 486 compat_datafellows(remote_version); 487 488 if (datafellows & SSH_BUG_PROBE) { 489 logit("probed from %s with %s. Don't panic.", 490 get_remote_ipaddr(), client_version_string); 491 cleanup_exit(255); 492 } 493 494 if (datafellows & SSH_BUG_SCANNER) { 495 logit("scanned from %s with %s. Don't panic.", 496 get_remote_ipaddr(), client_version_string); 497 cleanup_exit(255); 498 } 499 500 mismatch = 0; 501 switch (remote_major) { 502 case 1: 503 if (remote_minor == 99) { 504 if (options.protocol & SSH_PROTO_2) 505 enable_compat20(); 506 else 507 mismatch = 1; 508 break; 509 } 510 if (!(options.protocol & SSH_PROTO_1)) { 511 mismatch = 1; 512 break; 513 } 514 if (remote_minor < 3) { 515 packet_disconnect("Your ssh version is too old and " 516 "is no longer supported. Please install a newer version."); 517 } else if (remote_minor == 3) { 518 /* note that this disables agent-forwarding */ 519 enable_compat13(); 520 } 521 break; 522 case 2: 523 if (options.protocol & SSH_PROTO_2) { 524 enable_compat20(); 525 break; 526 } 527 /* FALLTHROUGH */ 528 default: 529 mismatch = 1; 530 break; 531 } 532 chop(server_version_string); 533 debug("Local version string %.200s", server_version_string); 534 535 if (mismatch) { 536 s = "Protocol major versions differ.\n"; 537 (void) atomicio(vwrite, sock_out, s, strlen(s)); 538 close(sock_in); 539 close(sock_out); 540 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 541 get_remote_ipaddr(), 542 server_version_string, client_version_string); 543 cleanup_exit(255); 544 } 545 } 546 547 /* Destroy the host and server keys. They will no longer be needed. */ 548 void 549 destroy_sensitive_data(void) 550 { 551 int i; 552 553 if (sensitive_data.server_key) { 554 key_free(sensitive_data.server_key); 555 sensitive_data.server_key = NULL; 556 } 557 for (i = 0; i < options.num_host_key_files; i++) { 558 if (sensitive_data.host_keys[i]) { 559 key_free(sensitive_data.host_keys[i]); 560 sensitive_data.host_keys[i] = NULL; 561 } 562 if (sensitive_data.host_certificates[i]) { 563 key_free(sensitive_data.host_certificates[i]); 564 sensitive_data.host_certificates[i] = NULL; 565 } 566 } 567 sensitive_data.ssh1_host_key = NULL; 568 memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); 569 } 570 571 /* Demote private to public keys for network child */ 572 void 573 demote_sensitive_data(void) 574 { 575 Key *tmp; 576 int i; 577 578 if (sensitive_data.server_key) { 579 tmp = key_demote(sensitive_data.server_key); 580 key_free(sensitive_data.server_key); 581 sensitive_data.server_key = tmp; 582 } 583 584 for (i = 0; i < options.num_host_key_files; i++) { 585 if (sensitive_data.host_keys[i]) { 586 tmp = key_demote(sensitive_data.host_keys[i]); 587 key_free(sensitive_data.host_keys[i]); 588 sensitive_data.host_keys[i] = tmp; 589 if (tmp->type == KEY_RSA1) 590 sensitive_data.ssh1_host_key = tmp; 591 } 592 /* Certs do not need demotion */ 593 } 594 595 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 596 } 597 598 static void 599 privsep_preauth_child(void) 600 { 601 u_int32_t rnd[256]; 602 gid_t gidset[1]; 603 604 /* Enable challenge-response authentication for privilege separation */ 605 privsep_challenge_enable(); 606 607 arc4random_stir(); 608 arc4random_buf(rnd, sizeof(rnd)); 609 RAND_seed(rnd, sizeof(rnd)); 610 611 /* Demote the private keys to public keys. */ 612 demote_sensitive_data(); 613 614 /* Change our root directory */ 615 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 616 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 617 strerror(errno)); 618 if (chdir("/") == -1) 619 fatal("chdir(\"/\"): %s", strerror(errno)); 620 621 /* Drop our privileges */ 622 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 623 (u_int)privsep_pw->pw_gid); 624 #if 0 625 /* XXX not ready, too heavy after chroot */ 626 do_setusercontext(privsep_pw); 627 #else 628 gidset[0] = privsep_pw->pw_gid; 629 if (setgroups(1, gidset) < 0) 630 fatal("setgroups: %.100s", strerror(errno)); 631 permanently_set_uid(privsep_pw); 632 #endif 633 } 634 635 static int 636 privsep_preauth(Authctxt *authctxt) 637 { 638 int status; 639 pid_t pid; 640 struct ssh_sandbox *box = NULL; 641 642 /* Set up unprivileged child process to deal with network data */ 643 pmonitor = monitor_init(); 644 /* Store a pointer to the kex for later rekeying */ 645 pmonitor->m_pkex = &xxx_kex; 646 647 if (use_privsep == PRIVSEP_SANDBOX) 648 box = ssh_sandbox_init(); 649 pid = fork(); 650 if (pid == -1) { 651 fatal("fork of unprivileged child failed"); 652 } else if (pid != 0) { 653 debug2("Network child is on pid %ld", (long)pid); 654 655 if (box != NULL) 656 ssh_sandbox_parent_preauth(box, pid); 657 pmonitor->m_pid = pid; 658 monitor_child_preauth(authctxt, pmonitor); 659 660 /* Sync memory */ 661 monitor_sync(pmonitor); 662 663 /* Wait for the child's exit status */ 664 while (waitpid(pid, &status, 0) < 0) { 665 if (errno != EINTR) 666 fatal("%s: waitpid: %s", __func__, 667 strerror(errno)); 668 } 669 if (WIFEXITED(status)) { 670 if (WEXITSTATUS(status) != 0) 671 fatal("%s: preauth child exited with status %d", 672 __func__, WEXITSTATUS(status)); 673 } else if (WIFSIGNALED(status)) 674 fatal("%s: preauth child terminated by signal %d", 675 __func__, WTERMSIG(status)); 676 if (box != NULL) 677 ssh_sandbox_parent_finish(box); 678 return 1; 679 } else { 680 /* child */ 681 close(pmonitor->m_sendfd); 682 close(pmonitor->m_log_recvfd); 683 684 /* Arrange for logging to be sent to the monitor */ 685 set_log_handler(mm_log_handler, pmonitor); 686 687 /* Demote the child */ 688 if (getuid() == 0 || geteuid() == 0) 689 privsep_preauth_child(); 690 setproctitle("%s", "[net]"); 691 if (box != NULL) 692 ssh_sandbox_child(box); 693 694 return 0; 695 } 696 } 697 698 static void 699 privsep_postauth(Authctxt *authctxt) 700 { 701 u_int32_t rnd[256]; 702 703 #ifdef DISABLE_FD_PASSING 704 if (1) { 705 #else 706 if (authctxt->pw->pw_uid == 0 || options.use_login) { 707 #endif 708 /* File descriptor passing is broken or root login */ 709 use_privsep = 0; 710 goto skip; 711 } 712 713 /* New socket pair */ 714 monitor_reinit(pmonitor); 715 716 pmonitor->m_pid = fork(); 717 if (pmonitor->m_pid == -1) 718 fatal("fork of unprivileged child failed"); 719 else if (pmonitor->m_pid != 0) { 720 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 721 buffer_clear(&loginmsg); 722 monitor_child_postauth(pmonitor); 723 724 /* NEVERREACHED */ 725 exit(0); 726 } 727 728 /* child */ 729 730 close(pmonitor->m_sendfd); 731 pmonitor->m_sendfd = -1; 732 733 /* Demote the private keys to public keys. */ 734 demote_sensitive_data(); 735 736 arc4random_stir(); 737 arc4random_buf(rnd, sizeof(rnd)); 738 RAND_seed(rnd, sizeof(rnd)); 739 740 /* Drop privileges */ 741 do_setusercontext(authctxt->pw); 742 743 skip: 744 /* It is safe now to apply the key state */ 745 monitor_apply_keystate(pmonitor); 746 747 /* 748 * Tell the packet layer that authentication was successful, since 749 * this information is not part of the key state. 750 */ 751 packet_set_authenticated(); 752 } 753 754 static char * 755 list_hostkey_types(void) 756 { 757 Buffer b; 758 const char *p; 759 char *ret; 760 int i; 761 Key *key; 762 763 buffer_init(&b); 764 for (i = 0; i < options.num_host_key_files; i++) { 765 key = sensitive_data.host_keys[i]; 766 if (key == NULL) 767 continue; 768 switch (key->type) { 769 case KEY_RSA: 770 case KEY_DSA: 771 case KEY_ECDSA: 772 if (buffer_len(&b) > 0) 773 buffer_append(&b, ",", 1); 774 p = key_ssh_name(key); 775 buffer_append(&b, p, strlen(p)); 776 break; 777 } 778 /* If the private key has a cert peer, then list that too */ 779 key = sensitive_data.host_certificates[i]; 780 if (key == NULL) 781 continue; 782 switch (key->type) { 783 case KEY_RSA_CERT_V00: 784 case KEY_DSA_CERT_V00: 785 case KEY_RSA_CERT: 786 case KEY_DSA_CERT: 787 case KEY_ECDSA_CERT: 788 if (buffer_len(&b) > 0) 789 buffer_append(&b, ",", 1); 790 p = key_ssh_name(key); 791 buffer_append(&b, p, strlen(p)); 792 break; 793 } 794 } 795 buffer_append(&b, "\0", 1); 796 ret = xstrdup(buffer_ptr(&b)); 797 buffer_free(&b); 798 debug("list_hostkey_types: %s", ret); 799 return ret; 800 } 801 802 static Key * 803 get_hostkey_by_type(int type, int need_private) 804 { 805 int i; 806 Key *key; 807 808 for (i = 0; i < options.num_host_key_files; i++) { 809 switch (type) { 810 case KEY_RSA_CERT_V00: 811 case KEY_DSA_CERT_V00: 812 case KEY_RSA_CERT: 813 case KEY_DSA_CERT: 814 case KEY_ECDSA_CERT: 815 key = sensitive_data.host_certificates[i]; 816 break; 817 default: 818 key = sensitive_data.host_keys[i]; 819 break; 820 } 821 if (key != NULL && key->type == type) 822 return need_private ? 823 sensitive_data.host_keys[i] : key; 824 } 825 return NULL; 826 } 827 828 Key * 829 get_hostkey_public_by_type(int type) 830 { 831 return get_hostkey_by_type(type, 0); 832 } 833 834 Key * 835 get_hostkey_private_by_type(int type) 836 { 837 return get_hostkey_by_type(type, 1); 838 } 839 840 Key * 841 get_hostkey_by_index(int ind) 842 { 843 if (ind < 0 || ind >= options.num_host_key_files) 844 return (NULL); 845 return (sensitive_data.host_keys[ind]); 846 } 847 848 int 849 get_hostkey_index(Key *key) 850 { 851 int i; 852 853 for (i = 0; i < options.num_host_key_files; i++) { 854 if (key_is_cert(key)) { 855 if (key == sensitive_data.host_certificates[i]) 856 return (i); 857 } else { 858 if (key == sensitive_data.host_keys[i]) 859 return (i); 860 } 861 } 862 return (-1); 863 } 864 865 /* 866 * returns 1 if connection should be dropped, 0 otherwise. 867 * dropping starts at connection #max_startups_begin with a probability 868 * of (max_startups_rate/100). the probability increases linearly until 869 * all connections are dropped for startups > max_startups 870 */ 871 static int 872 drop_connection(int startups) 873 { 874 int p, r; 875 876 if (startups < options.max_startups_begin) 877 return 0; 878 if (startups >= options.max_startups) 879 return 1; 880 if (options.max_startups_rate == 100) 881 return 1; 882 883 p = 100 - options.max_startups_rate; 884 p *= startups - options.max_startups_begin; 885 p /= options.max_startups - options.max_startups_begin; 886 p += options.max_startups_rate; 887 r = arc4random_uniform(100); 888 889 debug("drop_connection: p %d, r %d", p, r); 890 return (r < p) ? 1 : 0; 891 } 892 893 static void 894 usage(void) 895 { 896 fprintf(stderr, "%s, %s\n", 897 SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); 898 fprintf(stderr, 899 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 900 " [-f config_file] [-g login_grace_time] [-h host_key_file]\n" 901 " [-k key_gen_time] [-o option] [-p port] [-u len]\n" 902 ); 903 exit(1); 904 } 905 906 static void 907 send_rexec_state(int fd, Buffer *conf) 908 { 909 Buffer m; 910 911 debug3("%s: entering fd = %d config len %d", __func__, fd, 912 buffer_len(conf)); 913 914 /* 915 * Protocol from reexec master to child: 916 * string configuration 917 * u_int ephemeral_key_follows 918 * bignum e (only if ephemeral_key_follows == 1) 919 * bignum n " 920 * bignum d " 921 * bignum iqmp " 922 * bignum p " 923 * bignum q " 924 * string rngseed (only if OpenSSL is not self-seeded) 925 */ 926 buffer_init(&m); 927 buffer_put_cstring(&m, buffer_ptr(conf)); 928 929 if (sensitive_data.server_key != NULL && 930 sensitive_data.server_key->type == KEY_RSA1) { 931 buffer_put_int(&m, 1); 932 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 933 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 934 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 935 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 936 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 937 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 938 } else 939 buffer_put_int(&m, 0); 940 941 #ifndef OPENSSL_PRNG_ONLY 942 rexec_send_rng_seed(&m); 943 #endif 944 945 if (ssh_msg_send(fd, 0, &m) == -1) 946 fatal("%s: ssh_msg_send failed", __func__); 947 948 buffer_free(&m); 949 950 debug3("%s: done", __func__); 951 } 952 953 static void 954 recv_rexec_state(int fd, Buffer *conf) 955 { 956 Buffer m; 957 char *cp; 958 u_int len; 959 960 debug3("%s: entering fd = %d", __func__, fd); 961 962 buffer_init(&m); 963 964 if (ssh_msg_recv(fd, &m) == -1) 965 fatal("%s: ssh_msg_recv failed", __func__); 966 if (buffer_get_char(&m) != 0) 967 fatal("%s: rexec version mismatch", __func__); 968 969 cp = buffer_get_string(&m, &len); 970 if (conf != NULL) 971 buffer_append(conf, cp, len + 1); 972 xfree(cp); 973 974 if (buffer_get_int(&m)) { 975 if (sensitive_data.server_key != NULL) 976 key_free(sensitive_data.server_key); 977 sensitive_data.server_key = key_new_private(KEY_RSA1); 978 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 979 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 980 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 981 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 982 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 983 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 984 rsa_generate_additional_parameters( 985 sensitive_data.server_key->rsa); 986 } 987 988 #ifndef OPENSSL_PRNG_ONLY 989 rexec_recv_rng_seed(&m); 990 #endif 991 992 buffer_free(&m); 993 994 debug3("%s: done", __func__); 995 } 996 997 /* Accept a connection from inetd */ 998 static void 999 server_accept_inetd(int *sock_in, int *sock_out) 1000 { 1001 int fd; 1002 1003 startup_pipe = -1; 1004 if (rexeced_flag) { 1005 close(REEXEC_CONFIG_PASS_FD); 1006 *sock_in = *sock_out = dup(STDIN_FILENO); 1007 if (!debug_flag) { 1008 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1009 close(REEXEC_STARTUP_PIPE_FD); 1010 } 1011 } else { 1012 *sock_in = dup(STDIN_FILENO); 1013 *sock_out = dup(STDOUT_FILENO); 1014 } 1015 /* 1016 * We intentionally do not close the descriptors 0, 1, and 2 1017 * as our code for setting the descriptors won't work if 1018 * ttyfd happens to be one of those. 1019 */ 1020 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1021 dup2(fd, STDIN_FILENO); 1022 dup2(fd, STDOUT_FILENO); 1023 if (fd > STDOUT_FILENO) 1024 close(fd); 1025 } 1026 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1027 } 1028 1029 /* 1030 * Listen for TCP connections 1031 */ 1032 static void 1033 server_listen(void) 1034 { 1035 int ret, listen_sock, on = 1; 1036 struct addrinfo *ai; 1037 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1038 int socksize; 1039 socklen_t len; 1040 1041 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1042 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1043 continue; 1044 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1045 fatal("Too many listen sockets. " 1046 "Enlarge MAX_LISTEN_SOCKS"); 1047 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1048 ntop, sizeof(ntop), strport, sizeof(strport), 1049 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1050 error("getnameinfo failed: %.100s", 1051 ssh_gai_strerror(ret)); 1052 continue; 1053 } 1054 /* Create socket for listening. */ 1055 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1056 ai->ai_protocol); 1057 if (listen_sock < 0) { 1058 /* kernel may not support ipv6 */ 1059 verbose("socket: %.100s", strerror(errno)); 1060 continue; 1061 } 1062 if (set_nonblock(listen_sock) == -1) { 1063 close(listen_sock); 1064 continue; 1065 } 1066 /* 1067 * Set socket options. 1068 * Allow local port reuse in TIME_WAIT. 1069 */ 1070 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1071 &on, sizeof(on)) == -1) 1072 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1073 1074 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1075 if (ai->ai_family == AF_INET6) 1076 sock_set_v6only(listen_sock); 1077 1078 debug("Bind to port %s on %s.", strport, ntop); 1079 1080 len = sizeof(socksize); 1081 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len); 1082 debug("Server TCP RWIN socket size: %d", socksize); 1083 debug("HPN Buffer Size: %d", options.hpn_buffer_size); 1084 1085 /* Bind the socket to the desired port. */ 1086 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1087 error("Bind to port %s on %s failed: %.200s.", 1088 strport, ntop, strerror(errno)); 1089 close(listen_sock); 1090 continue; 1091 } 1092 listen_socks[num_listen_socks] = listen_sock; 1093 num_listen_socks++; 1094 1095 /* Start listening on the port. */ 1096 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1097 fatal("listen on [%s]:%s: %.100s", 1098 ntop, strport, strerror(errno)); 1099 logit("Server listening on %s port %s.", ntop, strport); 1100 } 1101 freeaddrinfo(options.listen_addrs); 1102 1103 if (!num_listen_socks) 1104 fatal("Cannot bind any address."); 1105 } 1106 1107 /* 1108 * The main TCP accept loop. Note that, for the non-debug case, returns 1109 * from this function are in a forked subprocess. 1110 */ 1111 static void 1112 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1113 { 1114 fd_set *fdset; 1115 int i, j, ret, maxfd; 1116 int key_used = 0, startups = 0; 1117 int startup_p[2] = { -1 , -1 }; 1118 struct sockaddr_storage from; 1119 socklen_t fromlen; 1120 pid_t pid; 1121 1122 /* setup fd set for accept */ 1123 fdset = NULL; 1124 maxfd = 0; 1125 for (i = 0; i < num_listen_socks; i++) 1126 if (listen_socks[i] > maxfd) 1127 maxfd = listen_socks[i]; 1128 /* pipes connected to unauthenticated childs */ 1129 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1130 for (i = 0; i < options.max_startups; i++) 1131 startup_pipes[i] = -1; 1132 1133 /* 1134 * Stay listening for connections until the system crashes or 1135 * the daemon is killed with a signal. 1136 */ 1137 for (;;) { 1138 if (received_sighup) 1139 sighup_restart(); 1140 if (fdset != NULL) 1141 xfree(fdset); 1142 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1143 sizeof(fd_mask)); 1144 1145 for (i = 0; i < num_listen_socks; i++) 1146 FD_SET(listen_socks[i], fdset); 1147 for (i = 0; i < options.max_startups; i++) 1148 if (startup_pipes[i] != -1) 1149 FD_SET(startup_pipes[i], fdset); 1150 1151 /* Wait in select until there is a connection. */ 1152 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1153 if (ret < 0 && errno != EINTR) 1154 error("select: %.100s", strerror(errno)); 1155 if (received_sigterm) { 1156 logit("Received signal %d; terminating.", 1157 (int) received_sigterm); 1158 close_listen_socks(); 1159 unlink(options.pid_file); 1160 exit(received_sigterm == SIGTERM ? 0 : 255); 1161 } 1162 if (key_used && key_do_regen) { 1163 generate_ephemeral_server_key(); 1164 key_used = 0; 1165 key_do_regen = 0; 1166 } 1167 if (ret < 0) 1168 continue; 1169 1170 for (i = 0; i < options.max_startups; i++) 1171 if (startup_pipes[i] != -1 && 1172 FD_ISSET(startup_pipes[i], fdset)) { 1173 /* 1174 * the read end of the pipe is ready 1175 * if the child has closed the pipe 1176 * after successful authentication 1177 * or if the child has died 1178 */ 1179 close(startup_pipes[i]); 1180 startup_pipes[i] = -1; 1181 startups--; 1182 } 1183 for (i = 0; i < num_listen_socks; i++) { 1184 if (!FD_ISSET(listen_socks[i], fdset)) 1185 continue; 1186 fromlen = sizeof(from); 1187 *newsock = accept(listen_socks[i], 1188 (struct sockaddr *)&from, &fromlen); 1189 if (*newsock < 0) { 1190 if (errno != EINTR && errno != EAGAIN && 1191 errno != EWOULDBLOCK) 1192 error("accept: %.100s", strerror(errno)); 1193 continue; 1194 } 1195 if (unset_nonblock(*newsock) == -1) { 1196 close(*newsock); 1197 continue; 1198 } 1199 if (drop_connection(startups) == 1) { 1200 debug("drop connection #%d", startups); 1201 close(*newsock); 1202 continue; 1203 } 1204 if (pipe(startup_p) == -1) { 1205 close(*newsock); 1206 continue; 1207 } 1208 1209 if (rexec_flag && socketpair(AF_UNIX, 1210 SOCK_STREAM, 0, config_s) == -1) { 1211 error("reexec socketpair: %s", 1212 strerror(errno)); 1213 close(*newsock); 1214 close(startup_p[0]); 1215 close(startup_p[1]); 1216 continue; 1217 } 1218 1219 for (j = 0; j < options.max_startups; j++) 1220 if (startup_pipes[j] == -1) { 1221 startup_pipes[j] = startup_p[0]; 1222 if (maxfd < startup_p[0]) 1223 maxfd = startup_p[0]; 1224 startups++; 1225 break; 1226 } 1227 1228 /* 1229 * Got connection. Fork a child to handle it, unless 1230 * we are in debugging mode. 1231 */ 1232 if (debug_flag) { 1233 /* 1234 * In debugging mode. Close the listening 1235 * socket, and start processing the 1236 * connection without forking. 1237 */ 1238 debug("Server will not fork when running in debugging mode."); 1239 close_listen_socks(); 1240 *sock_in = *newsock; 1241 *sock_out = *newsock; 1242 close(startup_p[0]); 1243 close(startup_p[1]); 1244 startup_pipe = -1; 1245 pid = getpid(); 1246 if (rexec_flag) { 1247 send_rexec_state(config_s[0], 1248 &cfg); 1249 close(config_s[0]); 1250 } 1251 break; 1252 } 1253 1254 /* 1255 * Normal production daemon. Fork, and have 1256 * the child process the connection. The 1257 * parent continues listening. 1258 */ 1259 platform_pre_fork(); 1260 if ((pid = fork()) == 0) { 1261 /* 1262 * Child. Close the listening and 1263 * max_startup sockets. Start using 1264 * the accepted socket. Reinitialize 1265 * logging (since our pid has changed). 1266 * We break out of the loop to handle 1267 * the connection. 1268 */ 1269 platform_post_fork_child(); 1270 startup_pipe = startup_p[1]; 1271 close_startup_pipes(); 1272 close_listen_socks(); 1273 *sock_in = *newsock; 1274 *sock_out = *newsock; 1275 log_init(__progname, 1276 options.log_level, 1277 options.log_facility, 1278 log_stderr); 1279 if (rexec_flag) 1280 close(config_s[0]); 1281 break; 1282 } 1283 1284 /* Parent. Stay in the loop. */ 1285 platform_post_fork_parent(pid); 1286 if (pid < 0) 1287 error("fork: %.100s", strerror(errno)); 1288 else 1289 debug("Forked child %ld.", (long)pid); 1290 1291 close(startup_p[1]); 1292 1293 if (rexec_flag) { 1294 send_rexec_state(config_s[0], &cfg); 1295 close(config_s[0]); 1296 close(config_s[1]); 1297 } 1298 1299 /* 1300 * Mark that the key has been used (it 1301 * was "given" to the child). 1302 */ 1303 if ((options.protocol & SSH_PROTO_1) && 1304 key_used == 0) { 1305 /* Schedule server key regeneration alarm. */ 1306 signal(SIGALRM, key_regeneration_alarm); 1307 alarm(options.key_regeneration_time); 1308 key_used = 1; 1309 } 1310 1311 close(*newsock); 1312 1313 /* 1314 * Ensure that our random state differs 1315 * from that of the child 1316 */ 1317 arc4random_stir(); 1318 } 1319 1320 /* child process check (or debug mode) */ 1321 if (num_listen_socks < 0) 1322 break; 1323 } 1324 } 1325 1326 1327 /* 1328 * Main program for the daemon. 1329 */ 1330 int 1331 main(int ac, char **av) 1332 { 1333 extern char *optarg; 1334 extern int optind; 1335 int opt, i, j, on = 1; 1336 int sock_in = -1, sock_out = -1, newsock = -1; 1337 const char *remote_ip; 1338 char *test_user = NULL, *test_host = NULL, *test_addr = NULL; 1339 int remote_port; 1340 char *line, *p, *cp; 1341 int config_s[2] = { -1 , -1 }; 1342 u_int64_t ibytes, obytes; 1343 mode_t new_umask; 1344 Key *key; 1345 Authctxt *authctxt; 1346 1347 #ifdef HAVE_SECUREWARE 1348 (void)set_auth_parameters(ac, av); 1349 #endif 1350 __progname = ssh_get_progname(av[0]); 1351 1352 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1353 saved_argc = ac; 1354 rexec_argc = ac; 1355 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1356 for (i = 0; i < ac; i++) 1357 saved_argv[i] = xstrdup(av[i]); 1358 saved_argv[i] = NULL; 1359 1360 #ifndef HAVE_SETPROCTITLE 1361 /* Prepare for later setproctitle emulation */ 1362 compat_init_setproctitle(ac, av); 1363 av = saved_argv; 1364 #endif 1365 1366 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1367 debug("setgroups(): %.200s", strerror(errno)); 1368 1369 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1370 sanitise_stdfd(); 1371 1372 /* Initialize configuration options to their default values. */ 1373 initialize_server_options(&options); 1374 1375 /* Parse command-line arguments. */ 1376 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) { 1377 switch (opt) { 1378 case '4': 1379 options.address_family = AF_INET; 1380 break; 1381 case '6': 1382 options.address_family = AF_INET6; 1383 break; 1384 case 'f': 1385 config_file_name = optarg; 1386 break; 1387 case 'c': 1388 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1389 fprintf(stderr, "too many host certificates.\n"); 1390 exit(1); 1391 } 1392 options.host_cert_files[options.num_host_cert_files++] = 1393 derelativise_path(optarg); 1394 break; 1395 case 'd': 1396 if (debug_flag == 0) { 1397 debug_flag = 1; 1398 options.log_level = SYSLOG_LEVEL_DEBUG1; 1399 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1400 options.log_level++; 1401 break; 1402 case 'D': 1403 no_daemon_flag = 1; 1404 break; 1405 case 'e': 1406 log_stderr = 1; 1407 break; 1408 case 'i': 1409 inetd_flag = 1; 1410 break; 1411 case 'r': 1412 rexec_flag = 0; 1413 break; 1414 case 'R': 1415 rexeced_flag = 1; 1416 inetd_flag = 1; 1417 break; 1418 case 'Q': 1419 /* ignored */ 1420 break; 1421 case 'q': 1422 options.log_level = SYSLOG_LEVEL_QUIET; 1423 break; 1424 case 'b': 1425 options.server_key_bits = (int)strtonum(optarg, 256, 1426 32768, NULL); 1427 break; 1428 case 'p': 1429 options.ports_from_cmdline = 1; 1430 if (options.num_ports >= MAX_PORTS) { 1431 fprintf(stderr, "too many ports.\n"); 1432 exit(1); 1433 } 1434 options.ports[options.num_ports++] = a2port(optarg); 1435 if (options.ports[options.num_ports-1] <= 0) { 1436 fprintf(stderr, "Bad port number.\n"); 1437 exit(1); 1438 } 1439 break; 1440 case 'g': 1441 if ((options.login_grace_time = convtime(optarg)) == -1) { 1442 fprintf(stderr, "Invalid login grace time.\n"); 1443 exit(1); 1444 } 1445 break; 1446 case 'k': 1447 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1448 fprintf(stderr, "Invalid key regeneration interval.\n"); 1449 exit(1); 1450 } 1451 break; 1452 case 'h': 1453 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1454 fprintf(stderr, "too many host keys.\n"); 1455 exit(1); 1456 } 1457 options.host_key_files[options.num_host_key_files++] = 1458 derelativise_path(optarg); 1459 break; 1460 case 't': 1461 test_flag = 1; 1462 break; 1463 case 'T': 1464 test_flag = 2; 1465 break; 1466 case 'C': 1467 cp = optarg; 1468 while ((p = strsep(&cp, ",")) && *p != '\0') { 1469 if (strncmp(p, "addr=", 5) == 0) 1470 test_addr = xstrdup(p + 5); 1471 else if (strncmp(p, "host=", 5) == 0) 1472 test_host = xstrdup(p + 5); 1473 else if (strncmp(p, "user=", 5) == 0) 1474 test_user = xstrdup(p + 5); 1475 else { 1476 fprintf(stderr, "Invalid test " 1477 "mode specification %s\n", p); 1478 exit(1); 1479 } 1480 } 1481 break; 1482 case 'u': 1483 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1484 if (utmp_len > MAXHOSTNAMELEN) { 1485 fprintf(stderr, "Invalid utmp length.\n"); 1486 exit(1); 1487 } 1488 break; 1489 case 'o': 1490 line = xstrdup(optarg); 1491 if (process_server_config_line(&options, line, 1492 "command-line", 0, NULL, NULL, NULL, NULL) != 0) 1493 exit(1); 1494 xfree(line); 1495 break; 1496 case '?': 1497 default: 1498 usage(); 1499 break; 1500 } 1501 } 1502 if (rexeced_flag || inetd_flag) 1503 rexec_flag = 0; 1504 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1505 fatal("sshd re-exec requires execution with an absolute path"); 1506 if (rexeced_flag) 1507 closefrom(REEXEC_MIN_FREE_FD); 1508 else 1509 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1510 1511 OpenSSL_add_all_algorithms(); 1512 1513 /* 1514 * Force logging to stderr until we have loaded the private host 1515 * key (unless started from inetd) 1516 */ 1517 log_init(__progname, 1518 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1519 SYSLOG_LEVEL_INFO : options.log_level, 1520 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1521 SYSLOG_FACILITY_AUTH : options.log_facility, 1522 log_stderr || !inetd_flag); 1523 1524 /* 1525 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1526 * root's environment 1527 */ 1528 if (getenv("KRB5CCNAME") != NULL) 1529 unsetenv("KRB5CCNAME"); 1530 1531 #ifdef _UNICOS 1532 /* Cray can define user privs drop all privs now! 1533 * Not needed on PRIV_SU systems! 1534 */ 1535 drop_cray_privs(); 1536 #endif 1537 1538 sensitive_data.server_key = NULL; 1539 sensitive_data.ssh1_host_key = NULL; 1540 sensitive_data.have_ssh1_key = 0; 1541 sensitive_data.have_ssh2_key = 0; 1542 1543 /* 1544 * If we're doing an extended config test, make sure we have all of 1545 * the parameters we need. If we're not doing an extended test, 1546 * do not silently ignore connection test params. 1547 */ 1548 if (test_flag >= 2 && 1549 (test_user != NULL || test_host != NULL || test_addr != NULL) 1550 && (test_user == NULL || test_host == NULL || test_addr == NULL)) 1551 fatal("user, host and addr are all required when testing " 1552 "Match configs"); 1553 if (test_flag < 2 && (test_user != NULL || test_host != NULL || 1554 test_addr != NULL)) 1555 fatal("Config test connection parameter (-C) provided without " 1556 "test mode (-T)"); 1557 1558 /* Fetch our configuration */ 1559 buffer_init(&cfg); 1560 if (rexeced_flag) 1561 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1562 else 1563 load_server_config(config_file_name, &cfg); 1564 1565 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1566 &cfg, NULL, NULL, NULL); 1567 1568 seed_rng(); 1569 1570 /* Fill in default values for those options not explicitly set. */ 1571 fill_default_server_options(&options); 1572 1573 /* challenge-response is implemented via keyboard interactive */ 1574 if (options.challenge_response_authentication) 1575 options.kbd_interactive_authentication = 1; 1576 1577 /* set default channel AF */ 1578 channel_set_af(options.address_family); 1579 1580 /* Check that there are no remaining arguments. */ 1581 if (optind < ac) { 1582 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1583 exit(1); 1584 } 1585 1586 debug("sshd version %.100s", SSH_RELEASE); 1587 1588 /* Store privilege separation user for later use if required. */ 1589 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1590 if (use_privsep || options.kerberos_authentication) 1591 fatal("Privilege separation user %s does not exist", 1592 SSH_PRIVSEP_USER); 1593 } else { 1594 memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd)); 1595 privsep_pw = pwcopy(privsep_pw); 1596 xfree(privsep_pw->pw_passwd); 1597 privsep_pw->pw_passwd = xstrdup("*"); 1598 } 1599 endpwent(); 1600 1601 /* load private host keys */ 1602 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1603 sizeof(Key *)); 1604 for (i = 0; i < options.num_host_key_files; i++) 1605 sensitive_data.host_keys[i] = NULL; 1606 1607 for (i = 0; i < options.num_host_key_files; i++) { 1608 key = key_load_private(options.host_key_files[i], "", NULL); 1609 sensitive_data.host_keys[i] = key; 1610 if (key == NULL) { 1611 error("Could not load host key: %s", 1612 options.host_key_files[i]); 1613 sensitive_data.host_keys[i] = NULL; 1614 continue; 1615 } 1616 switch (key->type) { 1617 case KEY_RSA1: 1618 sensitive_data.ssh1_host_key = key; 1619 sensitive_data.have_ssh1_key = 1; 1620 break; 1621 case KEY_RSA: 1622 case KEY_DSA: 1623 case KEY_ECDSA: 1624 sensitive_data.have_ssh2_key = 1; 1625 break; 1626 } 1627 debug("private host key: #%d type %d %s", i, key->type, 1628 key_type(key)); 1629 } 1630 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1631 logit("Disabling protocol version 1. Could not load host key"); 1632 options.protocol &= ~SSH_PROTO_1; 1633 } 1634 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1635 logit("Disabling protocol version 2. Could not load host key"); 1636 options.protocol &= ~SSH_PROTO_2; 1637 } 1638 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1639 logit("sshd: no hostkeys available -- exiting."); 1640 exit(1); 1641 } 1642 1643 /* 1644 * Load certificates. They are stored in an array at identical 1645 * indices to the public keys that they relate to. 1646 */ 1647 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1648 sizeof(Key *)); 1649 for (i = 0; i < options.num_host_key_files; i++) 1650 sensitive_data.host_certificates[i] = NULL; 1651 1652 for (i = 0; i < options.num_host_cert_files; i++) { 1653 key = key_load_public(options.host_cert_files[i], NULL); 1654 if (key == NULL) { 1655 error("Could not load host certificate: %s", 1656 options.host_cert_files[i]); 1657 continue; 1658 } 1659 if (!key_is_cert(key)) { 1660 error("Certificate file is not a certificate: %s", 1661 options.host_cert_files[i]); 1662 key_free(key); 1663 continue; 1664 } 1665 /* Find matching private key */ 1666 for (j = 0; j < options.num_host_key_files; j++) { 1667 if (key_equal_public(key, 1668 sensitive_data.host_keys[j])) { 1669 sensitive_data.host_certificates[j] = key; 1670 break; 1671 } 1672 } 1673 if (j >= options.num_host_key_files) { 1674 error("No matching private key for certificate: %s", 1675 options.host_cert_files[i]); 1676 key_free(key); 1677 continue; 1678 } 1679 sensitive_data.host_certificates[j] = key; 1680 debug("host certificate: #%d type %d %s", j, key->type, 1681 key_type(key)); 1682 } 1683 /* Check certain values for sanity. */ 1684 if (options.protocol & SSH_PROTO_1) { 1685 if (options.server_key_bits < 512 || 1686 options.server_key_bits > 32768) { 1687 fprintf(stderr, "Bad server key size.\n"); 1688 exit(1); 1689 } 1690 /* 1691 * Check that server and host key lengths differ sufficiently. This 1692 * is necessary to make double encryption work with rsaref. Oh, I 1693 * hate software patents. I dont know if this can go? Niels 1694 */ 1695 if (options.server_key_bits > 1696 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1697 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1698 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1699 SSH_KEY_BITS_RESERVED) { 1700 options.server_key_bits = 1701 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1702 SSH_KEY_BITS_RESERVED; 1703 debug("Forcing server key to %d bits to make it differ from host key.", 1704 options.server_key_bits); 1705 } 1706 } 1707 1708 if (use_privsep) { 1709 struct stat st; 1710 1711 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1712 (S_ISDIR(st.st_mode) == 0)) 1713 fatal("Missing privilege separation directory: %s", 1714 _PATH_PRIVSEP_CHROOT_DIR); 1715 1716 #ifdef HAVE_CYGWIN 1717 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1718 (st.st_uid != getuid () || 1719 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1720 #else 1721 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1722 #endif 1723 fatal("%s must be owned by root and not group or " 1724 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1725 } 1726 1727 if (test_flag > 1) { 1728 if (test_user != NULL && test_addr != NULL && test_host != NULL) 1729 parse_server_match_config(&options, test_user, 1730 test_host, test_addr); 1731 dump_config(&options); 1732 } 1733 1734 /* Configuration looks good, so exit if in test mode. */ 1735 if (test_flag) 1736 exit(0); 1737 1738 /* 1739 * Clear out any supplemental groups we may have inherited. This 1740 * prevents inadvertent creation of files with bad modes (in the 1741 * portable version at least, it's certainly possible for PAM 1742 * to create a file, and we can't control the code in every 1743 * module which might be used). 1744 */ 1745 if (setgroups(0, NULL) < 0) 1746 debug("setgroups() failed: %.200s", strerror(errno)); 1747 1748 if (rexec_flag) { 1749 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1750 for (i = 0; i < rexec_argc; i++) { 1751 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1752 rexec_argv[i] = saved_argv[i]; 1753 } 1754 rexec_argv[rexec_argc] = "-R"; 1755 rexec_argv[rexec_argc + 1] = NULL; 1756 } 1757 1758 /* Ensure that umask disallows at least group and world write */ 1759 new_umask = umask(0077) | 0022; 1760 (void) umask(new_umask); 1761 1762 /* Initialize the log (it is reinitialized below in case we forked). */ 1763 if (debug_flag && (!inetd_flag || rexeced_flag)) 1764 log_stderr = 1; 1765 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1766 1767 /* 1768 * If not in debugging mode, and not started from inetd, disconnect 1769 * from the controlling terminal, and fork. The original process 1770 * exits. 1771 */ 1772 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1773 #ifdef TIOCNOTTY 1774 int fd; 1775 #endif /* TIOCNOTTY */ 1776 if (daemon(0, 0) < 0) 1777 fatal("daemon() failed: %.200s", strerror(errno)); 1778 1779 /* Disconnect from the controlling tty. */ 1780 #ifdef TIOCNOTTY 1781 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1782 if (fd >= 0) { 1783 (void) ioctl(fd, TIOCNOTTY, NULL); 1784 close(fd); 1785 } 1786 #endif /* TIOCNOTTY */ 1787 } 1788 /* Reinitialize the log (because of the fork above). */ 1789 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1790 1791 /* Avoid killing the process in high-pressure swapping environments. */ 1792 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 1793 debug("madvise(): %.200s", strerror(errno)); 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 * Create a new session and process group since the 4.4BSD 1846 * setlogin() affects the entire process group. We don't 1847 * want the child to be able to affect the parent. 1848 */ 1849 #if !defined(SSHD_ACQUIRES_CTTY) 1850 /* 1851 * If setsid is called, on some platforms sshd will later acquire a 1852 * controlling terminal which will result in "could not set 1853 * controlling tty" errors. 1854 */ 1855 if (!debug_flag && !inetd_flag && setsid() < 0) 1856 error("setsid: %.100s", strerror(errno)); 1857 #endif 1858 1859 if (rexec_flag) { 1860 int fd; 1861 1862 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1863 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1864 dup2(newsock, STDIN_FILENO); 1865 dup2(STDIN_FILENO, STDOUT_FILENO); 1866 if (startup_pipe == -1) 1867 close(REEXEC_STARTUP_PIPE_FD); 1868 else 1869 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1870 1871 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1872 close(config_s[1]); 1873 if (startup_pipe != -1) 1874 close(startup_pipe); 1875 1876 execv(rexec_argv[0], rexec_argv); 1877 1878 /* Reexec has failed, fall back and continue */ 1879 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1880 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1881 log_init(__progname, options.log_level, 1882 options.log_facility, log_stderr); 1883 1884 /* Clean up fds */ 1885 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1886 close(config_s[1]); 1887 close(REEXEC_CONFIG_PASS_FD); 1888 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1889 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1890 dup2(fd, STDIN_FILENO); 1891 dup2(fd, STDOUT_FILENO); 1892 if (fd > STDERR_FILENO) 1893 close(fd); 1894 } 1895 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1896 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1897 } 1898 1899 /* Executed child processes don't need these. */ 1900 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1901 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1902 1903 /* 1904 * Disable the key regeneration alarm. We will not regenerate the 1905 * key since we are no longer in a position to give it to anyone. We 1906 * will not restart on SIGHUP since it no longer makes sense. 1907 */ 1908 alarm(0); 1909 signal(SIGALRM, SIG_DFL); 1910 signal(SIGHUP, SIG_DFL); 1911 signal(SIGTERM, SIG_DFL); 1912 signal(SIGQUIT, SIG_DFL); 1913 signal(SIGCHLD, SIG_DFL); 1914 signal(SIGINT, SIG_DFL); 1915 1916 #ifdef __FreeBSD__ 1917 /* 1918 * Initialize the resolver. This may not happen automatically 1919 * before privsep chroot(). 1920 */ 1921 if ((_res.options & RES_INIT) == 0) { 1922 debug("res_init()"); 1923 res_init(); 1924 } 1925 #ifdef GSSAPI 1926 /* 1927 * Force GSS-API to parse its configuration and load any 1928 * mechanism plugins. 1929 */ 1930 { 1931 gss_OID_set mechs; 1932 OM_uint32 minor_status; 1933 gss_indicate_mechs(&minor_status, &mechs); 1934 gss_release_oid_set(&minor_status, &mechs); 1935 } 1936 #endif 1937 #endif 1938 1939 /* 1940 * Register our connection. This turns encryption off because we do 1941 * not have a key. 1942 */ 1943 packet_set_connection(sock_in, sock_out); 1944 packet_set_server(); 1945 1946 /* Set SO_KEEPALIVE if requested. */ 1947 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 1948 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 1949 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1950 1951 if ((remote_port = get_remote_port()) < 0) { 1952 debug("get_remote_port failed"); 1953 cleanup_exit(255); 1954 } 1955 1956 /* 1957 * We use get_canonical_hostname with usedns = 0 instead of 1958 * get_remote_ipaddr here so IP options will be checked. 1959 */ 1960 (void) get_canonical_hostname(0); 1961 /* 1962 * The rest of the code depends on the fact that 1963 * get_remote_ipaddr() caches the remote ip, even if 1964 * the socket goes away. 1965 */ 1966 remote_ip = get_remote_ipaddr(); 1967 1968 #ifdef SSH_AUDIT_EVENTS 1969 audit_connection_from(remote_ip, remote_port); 1970 #endif 1971 #ifdef LIBWRAP 1972 allow_severity = options.log_facility|LOG_INFO; 1973 deny_severity = options.log_facility|LOG_WARNING; 1974 /* Check whether logins are denied from this host. */ 1975 if (packet_connection_is_on_socket()) { 1976 struct request_info req; 1977 1978 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 1979 fromhost(&req); 1980 1981 if (!hosts_access(&req)) { 1982 debug("Connection refused by tcp wrapper"); 1983 refuse(&req); 1984 /* NOTREACHED */ 1985 fatal("libwrap refuse returns"); 1986 } 1987 } 1988 #endif /* LIBWRAP */ 1989 1990 /* Log the connection. */ 1991 verbose("Connection from %.500s port %d", remote_ip, remote_port); 1992 1993 /* Set HPN options for the child. */ 1994 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size); 1995 1996 /* 1997 * We don't want to listen forever unless the other side 1998 * successfully authenticates itself. So we set up an alarm which is 1999 * cleared after successful authentication. A limit of zero 2000 * indicates no limit. Note that we don't set the alarm in debugging 2001 * mode; it is just annoying to have the server exit just when you 2002 * are about to discover the bug. 2003 */ 2004 signal(SIGALRM, grace_alarm_handler); 2005 if (!debug_flag) 2006 alarm(options.login_grace_time); 2007 2008 sshd_exchange_identification(sock_in, sock_out); 2009 2010 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 2011 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 2012 generate_ephemeral_server_key(); 2013 2014 packet_set_nonblocking(); 2015 2016 /* allocate authentication context */ 2017 authctxt = xcalloc(1, sizeof(*authctxt)); 2018 2019 authctxt->loginmsg = &loginmsg; 2020 2021 /* XXX global for cleanup, access from other modules */ 2022 the_authctxt = authctxt; 2023 2024 /* prepare buffer to collect messages to display to user after login */ 2025 buffer_init(&loginmsg); 2026 auth_debug_reset(); 2027 2028 if (use_privsep) 2029 if (privsep_preauth(authctxt) == 1) 2030 goto authenticated; 2031 2032 /* perform the key exchange */ 2033 /* authenticate user and start session */ 2034 if (compat20) { 2035 do_ssh2_kex(); 2036 do_authentication2(authctxt); 2037 } else { 2038 do_ssh1_kex(); 2039 do_authentication(authctxt); 2040 } 2041 /* 2042 * If we use privilege separation, the unprivileged child transfers 2043 * the current keystate and exits 2044 */ 2045 if (use_privsep) { 2046 mm_send_keystate(pmonitor); 2047 exit(0); 2048 } 2049 2050 authenticated: 2051 /* 2052 * Cancel the alarm we set to limit the time taken for 2053 * authentication. 2054 */ 2055 alarm(0); 2056 signal(SIGALRM, SIG_DFL); 2057 authctxt->authenticated = 1; 2058 if (startup_pipe != -1) { 2059 close(startup_pipe); 2060 startup_pipe = -1; 2061 } 2062 2063 #ifdef SSH_AUDIT_EVENTS 2064 audit_event(SSH_AUTH_SUCCESS); 2065 #endif 2066 2067 #ifdef GSSAPI 2068 if (options.gss_authentication) { 2069 temporarily_use_uid(authctxt->pw); 2070 ssh_gssapi_storecreds(); 2071 restore_uid(); 2072 } 2073 #endif 2074 #ifdef USE_PAM 2075 if (options.use_pam) { 2076 do_pam_setcred(1); 2077 do_pam_session(); 2078 } 2079 #endif 2080 2081 /* 2082 * In privilege separation, we fork another child and prepare 2083 * file descriptor passing. 2084 */ 2085 if (use_privsep) { 2086 privsep_postauth(authctxt); 2087 /* the monitor process [priv] will not return */ 2088 if (!compat20) 2089 destroy_sensitive_data(); 2090 } 2091 2092 packet_set_timeout(options.client_alive_interval, 2093 options.client_alive_count_max); 2094 2095 /* Start session. */ 2096 do_authenticated(authctxt); 2097 2098 /* The connection has been terminated. */ 2099 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 2100 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 2101 verbose("Transferred: sent %llu, received %llu bytes", 2102 (unsigned long long)obytes, (unsigned long long)ibytes); 2103 2104 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2105 2106 #ifdef USE_PAM 2107 if (options.use_pam) 2108 finish_pam(); 2109 #endif /* USE_PAM */ 2110 2111 #ifdef SSH_AUDIT_EVENTS 2112 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2113 #endif 2114 2115 packet_close(); 2116 2117 if (use_privsep) 2118 mm_terminate(); 2119 2120 exit(0); 2121 } 2122 2123 /* 2124 * Decrypt session_key_int using our private server key and private host key 2125 * (key with larger modulus first). 2126 */ 2127 int 2128 ssh1_session_key(BIGNUM *session_key_int) 2129 { 2130 int rsafail = 0; 2131 2132 if (BN_cmp(sensitive_data.server_key->rsa->n, 2133 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2134 /* Server key has bigger modulus. */ 2135 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2136 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2137 SSH_KEY_BITS_RESERVED) { 2138 fatal("do_connection: %s: " 2139 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2140 get_remote_ipaddr(), 2141 BN_num_bits(sensitive_data.server_key->rsa->n), 2142 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2143 SSH_KEY_BITS_RESERVED); 2144 } 2145 if (rsa_private_decrypt(session_key_int, session_key_int, 2146 sensitive_data.server_key->rsa) <= 0) 2147 rsafail++; 2148 if (rsa_private_decrypt(session_key_int, session_key_int, 2149 sensitive_data.ssh1_host_key->rsa) <= 0) 2150 rsafail++; 2151 } else { 2152 /* Host key has bigger modulus (or they are equal). */ 2153 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2154 BN_num_bits(sensitive_data.server_key->rsa->n) + 2155 SSH_KEY_BITS_RESERVED) { 2156 fatal("do_connection: %s: " 2157 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2158 get_remote_ipaddr(), 2159 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2160 BN_num_bits(sensitive_data.server_key->rsa->n), 2161 SSH_KEY_BITS_RESERVED); 2162 } 2163 if (rsa_private_decrypt(session_key_int, session_key_int, 2164 sensitive_data.ssh1_host_key->rsa) < 0) 2165 rsafail++; 2166 if (rsa_private_decrypt(session_key_int, session_key_int, 2167 sensitive_data.server_key->rsa) < 0) 2168 rsafail++; 2169 } 2170 return (rsafail); 2171 } 2172 /* 2173 * SSH1 key exchange 2174 */ 2175 static void 2176 do_ssh1_kex(void) 2177 { 2178 int i, len; 2179 int rsafail = 0; 2180 BIGNUM *session_key_int; 2181 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2182 u_char cookie[8]; 2183 u_int cipher_type, auth_mask, protocol_flags; 2184 2185 /* 2186 * Generate check bytes that the client must send back in the user 2187 * packet in order for it to be accepted; this is used to defy ip 2188 * spoofing attacks. Note that this only works against somebody 2189 * doing IP spoofing from a remote machine; any machine on the local 2190 * network can still see outgoing packets and catch the random 2191 * cookie. This only affects rhosts authentication, and this is one 2192 * of the reasons why it is inherently insecure. 2193 */ 2194 arc4random_buf(cookie, sizeof(cookie)); 2195 2196 /* 2197 * Send our public key. We include in the packet 64 bits of random 2198 * data that must be matched in the reply in order to prevent IP 2199 * spoofing. 2200 */ 2201 packet_start(SSH_SMSG_PUBLIC_KEY); 2202 for (i = 0; i < 8; i++) 2203 packet_put_char(cookie[i]); 2204 2205 /* Store our public server RSA key. */ 2206 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2207 packet_put_bignum(sensitive_data.server_key->rsa->e); 2208 packet_put_bignum(sensitive_data.server_key->rsa->n); 2209 2210 /* Store our public host RSA key. */ 2211 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2212 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2213 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2214 2215 /* Put protocol flags. */ 2216 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2217 2218 /* Declare which ciphers we support. */ 2219 packet_put_int(cipher_mask_ssh1(0)); 2220 2221 /* Declare supported authentication types. */ 2222 auth_mask = 0; 2223 if (options.rhosts_rsa_authentication) 2224 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2225 if (options.rsa_authentication) 2226 auth_mask |= 1 << SSH_AUTH_RSA; 2227 if (options.challenge_response_authentication == 1) 2228 auth_mask |= 1 << SSH_AUTH_TIS; 2229 if (options.password_authentication) 2230 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2231 packet_put_int(auth_mask); 2232 2233 /* Send the packet and wait for it to be sent. */ 2234 packet_send(); 2235 packet_write_wait(); 2236 2237 debug("Sent %d bit server key and %d bit host key.", 2238 BN_num_bits(sensitive_data.server_key->rsa->n), 2239 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2240 2241 /* Read clients reply (cipher type and session key). */ 2242 packet_read_expect(SSH_CMSG_SESSION_KEY); 2243 2244 /* Get cipher type and check whether we accept this. */ 2245 cipher_type = packet_get_char(); 2246 2247 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2248 packet_disconnect("Warning: client selects unsupported cipher."); 2249 2250 /* Get check bytes from the packet. These must match those we 2251 sent earlier with the public key packet. */ 2252 for (i = 0; i < 8; i++) 2253 if (cookie[i] != packet_get_char()) 2254 packet_disconnect("IP Spoofing check bytes do not match."); 2255 2256 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2257 2258 /* Get the encrypted integer. */ 2259 if ((session_key_int = BN_new()) == NULL) 2260 fatal("do_ssh1_kex: BN_new failed"); 2261 packet_get_bignum(session_key_int); 2262 2263 protocol_flags = packet_get_int(); 2264 packet_set_protocol_flags(protocol_flags); 2265 packet_check_eom(); 2266 2267 /* Decrypt session_key_int using host/server keys */ 2268 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2269 2270 /* 2271 * Extract session key from the decrypted integer. The key is in the 2272 * least significant 256 bits of the integer; the first byte of the 2273 * key is in the highest bits. 2274 */ 2275 if (!rsafail) { 2276 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2277 len = BN_num_bytes(session_key_int); 2278 if (len < 0 || (u_int)len > sizeof(session_key)) { 2279 error("do_ssh1_kex: bad session key len from %s: " 2280 "session_key_int %d > sizeof(session_key) %lu", 2281 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2282 rsafail++; 2283 } else { 2284 memset(session_key, 0, sizeof(session_key)); 2285 BN_bn2bin(session_key_int, 2286 session_key + sizeof(session_key) - len); 2287 2288 derive_ssh1_session_id( 2289 sensitive_data.ssh1_host_key->rsa->n, 2290 sensitive_data.server_key->rsa->n, 2291 cookie, session_id); 2292 /* 2293 * Xor the first 16 bytes of the session key with the 2294 * session id. 2295 */ 2296 for (i = 0; i < 16; i++) 2297 session_key[i] ^= session_id[i]; 2298 } 2299 } 2300 if (rsafail) { 2301 int bytes = BN_num_bytes(session_key_int); 2302 u_char *buf = xmalloc(bytes); 2303 MD5_CTX md; 2304 2305 logit("do_connection: generating a fake encryption key"); 2306 BN_bn2bin(session_key_int, buf); 2307 MD5_Init(&md); 2308 MD5_Update(&md, buf, bytes); 2309 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2310 MD5_Final(session_key, &md); 2311 MD5_Init(&md); 2312 MD5_Update(&md, session_key, 16); 2313 MD5_Update(&md, buf, bytes); 2314 MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 2315 MD5_Final(session_key + 16, &md); 2316 memset(buf, 0, bytes); 2317 xfree(buf); 2318 for (i = 0; i < 16; i++) 2319 session_id[i] = session_key[i] ^ session_key[i + 16]; 2320 } 2321 /* Destroy the private and public keys. No longer. */ 2322 destroy_sensitive_data(); 2323 2324 if (use_privsep) 2325 mm_ssh1_session_id(session_id); 2326 2327 /* Destroy the decrypted integer. It is no longer needed. */ 2328 BN_clear_free(session_key_int); 2329 2330 /* Set the session key. From this on all communications will be encrypted. */ 2331 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2332 2333 /* Destroy our copy of the session key. It is no longer needed. */ 2334 memset(session_key, 0, sizeof(session_key)); 2335 2336 debug("Received session key; encryption turned on."); 2337 2338 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2339 packet_start(SSH_SMSG_SUCCESS); 2340 packet_send(); 2341 packet_write_wait(); 2342 } 2343 2344 /* 2345 * SSH2 key exchange: diffie-hellman-group1-sha1 2346 */ 2347 static void 2348 do_ssh2_kex(void) 2349 { 2350 Kex *kex; 2351 2352 if (options.ciphers != NULL) { 2353 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2354 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2355 #ifdef NONE_CIPHER_ENABLED 2356 } else if (options.none_enabled == 1) { 2357 debug ("WARNING: None cipher enabled"); 2358 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2359 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE; 2360 #endif 2361 } 2362 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2363 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2364 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2365 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2366 2367 if (options.macs != NULL) { 2368 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2369 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2370 } 2371 if (options.compression == COMP_NONE) { 2372 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2373 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2374 } else if (options.compression == COMP_DELAYED) { 2375 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2376 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2377 } 2378 if (options.kex_algorithms != NULL) 2379 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 2380 2381 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); 2382 2383 /* start key exchange */ 2384 kex = kex_setup(myproposal); 2385 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2386 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2387 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2388 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2389 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2390 kex->server = 1; 2391 kex->client_version_string=client_version_string; 2392 kex->server_version_string=server_version_string; 2393 kex->load_host_public_key=&get_hostkey_public_by_type; 2394 kex->load_host_private_key=&get_hostkey_private_by_type; 2395 kex->host_key_index=&get_hostkey_index; 2396 2397 xxx_kex = kex; 2398 2399 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2400 2401 session_id2 = kex->session_id; 2402 session_id2_len = kex->session_id_len; 2403 2404 #ifdef DEBUG_KEXDH 2405 /* send 1st encrypted/maced/compressed message */ 2406 packet_start(SSH2_MSG_IGNORE); 2407 packet_put_cstring("markus"); 2408 packet_send(); 2409 packet_write_wait(); 2410 #endif 2411 debug("KEX done"); 2412 } 2413 2414 /* server specific fatal cleanup */ 2415 void 2416 cleanup_exit(int i) 2417 { 2418 if (the_authctxt) 2419 do_cleanup(the_authctxt); 2420 #ifdef SSH_AUDIT_EVENTS 2421 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2422 if (!use_privsep || mm_is_monitor()) 2423 audit_event(SSH_CONNECTION_ABANDON); 2424 #endif 2425 _exit(i); 2426 } 2427