1 /* $OpenBSD: sshd.c,v 1.428 2014/07/15 15:54:14 millert Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This program is the ssh daemon. It listens for connections from clients, 7 * and performs authentication, executes use commands or shell, and forwards 8 * information to/from the application to the user client over an encrypted 9 * connection. This can also handle forwarding of X11, TCP/IP, and 10 * authentication agent connections. 11 * 12 * As far as I am concerned, the code I have written for this software 13 * can be used freely for any purpose. Any derived versions of this 14 * software must be clearly marked as such, and if the derived work is 15 * incompatible with the protocol description in the RFC file, it must be 16 * called by a name other than "ssh" or "Secure Shell". 17 * 18 * SSH2 implementation: 19 * Privilege Separation: 20 * 21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 22 * Copyright (c) 2002 Niels Provos. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 43 */ 44 45 #include "includes.h" 46 __RCSID("$FreeBSD$"); 47 48 #include <sys/types.h> 49 #include <sys/ioctl.h> 50 #include <sys/mman.h> 51 #include <sys/socket.h> 52 #ifdef HAVE_SYS_STAT_H 53 # include <sys/stat.h> 54 #endif 55 #ifdef HAVE_SYS_TIME_H 56 # include <sys/time.h> 57 #endif 58 #include "openbsd-compat/sys-tree.h" 59 #include "openbsd-compat/sys-queue.h" 60 #include <sys/wait.h> 61 62 #include <errno.h> 63 #include <fcntl.h> 64 #include <netdb.h> 65 #ifdef HAVE_PATHS_H 66 #include <paths.h> 67 #endif 68 #include <grp.h> 69 #include <pwd.h> 70 #include <signal.h> 71 #include <stdarg.h> 72 #include <stdio.h> 73 #include <stdlib.h> 74 #include <string.h> 75 #include <unistd.h> 76 77 #ifdef WITH_OPENSSL 78 #include <openssl/dh.h> 79 #include <openssl/bn.h> 80 #include <openssl/rand.h> 81 #include "openbsd-compat/openssl-compat.h" 82 #endif 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_GSSAPI_H) 92 #include <gssapi/gssapi.h> 93 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_H) 94 #include <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 "misc.h" 108 #include "servconf.h" 109 #include "uidswap.h" 110 #include "compat.h" 111 #include "cipher.h" 112 #include "digest.h" 113 #include "key.h" 114 #include "kex.h" 115 #include "myproposal.h" 116 #include "authfile.h" 117 #include "pathnames.h" 118 #include "atomicio.h" 119 #include "canohost.h" 120 #include "hostfile.h" 121 #include "auth.h" 122 #include "authfd.h" 123 #include "msg.h" 124 #include "dispatch.h" 125 #include "channels.h" 126 #include "session.h" 127 #include "monitor_mm.h" 128 #include "monitor.h" 129 #ifdef GSSAPI 130 #include "ssh-gss.h" 131 #endif 132 #include "monitor_wrap.h" 133 #include "roaming.h" 134 #include "ssh-sandbox.h" 135 #include "version.h" 136 137 #ifdef LIBWRAP 138 #include <tcpd.h> 139 #include <syslog.h> 140 int allow_severity; 141 int deny_severity; 142 #endif /* LIBWRAP */ 143 144 #ifndef O_NOCTTY 145 #define O_NOCTTY 0 146 #endif 147 148 /* Re-exec fds */ 149 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 150 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 151 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 152 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 153 154 extern char *__progname; 155 156 /* Server configuration options. */ 157 ServerOptions options; 158 159 /* Name of the server configuration file. */ 160 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 161 162 /* 163 * Debug mode flag. This can be set on the command line. If debug 164 * mode is enabled, extra debugging output will be sent to the system 165 * log, the daemon will not go to background, and will exit after processing 166 * the first connection. 167 */ 168 int debug_flag = 0; 169 170 /* Flag indicating that the daemon should only test the configuration and keys. */ 171 int test_flag = 0; 172 173 /* Flag indicating that the daemon is being started from inetd. */ 174 int inetd_flag = 0; 175 176 /* Flag indicating that sshd should not detach and become a daemon. */ 177 int no_daemon_flag = 0; 178 179 /* debug goes to stderr unless inetd_flag is set */ 180 int log_stderr = 0; 181 182 /* Saved arguments to main(). */ 183 char **saved_argv; 184 int saved_argc; 185 186 /* re-exec */ 187 int rexeced_flag = 0; 188 int rexec_flag = 1; 189 int rexec_argc = 0; 190 char **rexec_argv; 191 192 /* 193 * The sockets that the server is listening; this is used in the SIGHUP 194 * signal handler. 195 */ 196 #define MAX_LISTEN_SOCKS 16 197 int listen_socks[MAX_LISTEN_SOCKS]; 198 int num_listen_socks = 0; 199 200 /* 201 * the client's version string, passed by sshd2 in compat mode. if != NULL, 202 * sshd will skip the version-number exchange 203 */ 204 char *client_version_string = NULL; 205 char *server_version_string = NULL; 206 207 /* for rekeying XXX fixme */ 208 Kex *xxx_kex; 209 210 /* Daemon's agent connection */ 211 AuthenticationConnection *auth_conn = NULL; 212 int have_agent = 0; 213 214 /* 215 * Any really sensitive data in the application is contained in this 216 * structure. The idea is that this structure could be locked into memory so 217 * that the pages do not get written into swap. However, there are some 218 * problems. The private key contains BIGNUMs, and we do not (in principle) 219 * have access to the internals of them, and locking just the structure is 220 * not very useful. Currently, memory locking is not implemented. 221 */ 222 struct { 223 Key *server_key; /* ephemeral server key */ 224 Key *ssh1_host_key; /* ssh1 host key */ 225 Key **host_keys; /* all private host keys */ 226 Key **host_pubkeys; /* all public host keys */ 227 Key **host_certificates; /* all public host certificates */ 228 int have_ssh1_key; 229 int have_ssh2_key; 230 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 231 } sensitive_data; 232 233 /* 234 * Flag indicating whether the RSA server key needs to be regenerated. 235 * Is set in the SIGALRM handler and cleared when the key is regenerated. 236 */ 237 static volatile sig_atomic_t key_do_regen = 0; 238 239 /* This is set to true when a signal is received. */ 240 static volatile sig_atomic_t received_sighup = 0; 241 static volatile sig_atomic_t received_sigterm = 0; 242 243 /* session identifier, used by RSA-auth */ 244 u_char session_id[16]; 245 246 /* same for ssh2 */ 247 u_char *session_id2 = NULL; 248 u_int session_id2_len = 0; 249 250 /* record remote hostname or ip */ 251 u_int utmp_len = MAXHOSTNAMELEN; 252 253 /* options.max_startup sized array of fd ints */ 254 int *startup_pipes = NULL; 255 int startup_pipe; /* in child */ 256 257 /* variables used for privilege separation */ 258 int use_privsep = -1; 259 struct monitor *pmonitor = NULL; 260 int privsep_is_preauth = 1; 261 262 /* global authentication context */ 263 Authctxt *the_authctxt = NULL; 264 265 /* sshd_config buffer */ 266 Buffer cfg; 267 268 /* message to be displayed after login */ 269 Buffer loginmsg; 270 271 /* Unprivileged user */ 272 struct passwd *privsep_pw = NULL; 273 274 /* Prototypes for various functions defined later in this file. */ 275 void destroy_sensitive_data(void); 276 void demote_sensitive_data(void); 277 278 #ifdef WITH_SSH1 279 static void do_ssh1_kex(void); 280 #endif 281 static void do_ssh2_kex(void); 282 283 /* 284 * Close all listening sockets 285 */ 286 static void 287 close_listen_socks(void) 288 { 289 int i; 290 291 for (i = 0; i < num_listen_socks; i++) 292 close(listen_socks[i]); 293 num_listen_socks = -1; 294 } 295 296 static void 297 close_startup_pipes(void) 298 { 299 int i; 300 301 if (startup_pipes) 302 for (i = 0; i < options.max_startups; i++) 303 if (startup_pipes[i] != -1) 304 close(startup_pipes[i]); 305 } 306 307 /* 308 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 309 * the effect is to reread the configuration file (and to regenerate 310 * the server key). 311 */ 312 313 /*ARGSUSED*/ 314 static void 315 sighup_handler(int sig) 316 { 317 int save_errno = errno; 318 319 received_sighup = 1; 320 signal(SIGHUP, sighup_handler); 321 errno = save_errno; 322 } 323 324 /* 325 * Called from the main program after receiving SIGHUP. 326 * Restarts the server. 327 */ 328 static void 329 sighup_restart(void) 330 { 331 logit("Received SIGHUP; restarting."); 332 platform_pre_restart(); 333 close_listen_socks(); 334 close_startup_pipes(); 335 alarm(0); /* alarm timer persists across exec */ 336 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 337 execv(saved_argv[0], saved_argv); 338 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 339 strerror(errno)); 340 exit(1); 341 } 342 343 /* 344 * Generic signal handler for terminating signals in the master daemon. 345 */ 346 /*ARGSUSED*/ 347 static void 348 sigterm_handler(int sig) 349 { 350 received_sigterm = sig; 351 } 352 353 /* 354 * SIGCHLD handler. This is called whenever a child dies. This will then 355 * reap any zombies left by exited children. 356 */ 357 /*ARGSUSED*/ 358 static void 359 main_sigchld_handler(int sig) 360 { 361 int save_errno = errno; 362 pid_t pid; 363 int status; 364 365 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 366 (pid < 0 && errno == EINTR)) 367 ; 368 369 signal(SIGCHLD, main_sigchld_handler); 370 errno = save_errno; 371 } 372 373 /* 374 * Signal handler for the alarm after the login grace period has expired. 375 */ 376 /*ARGSUSED*/ 377 static void 378 grace_alarm_handler(int sig) 379 { 380 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 381 kill(pmonitor->m_pid, SIGALRM); 382 383 /* 384 * Try to kill any processes that we have spawned, E.g. authorized 385 * keys command helpers. 386 */ 387 if (getpgid(0) == getpid()) { 388 signal(SIGTERM, SIG_IGN); 389 kill(0, SIGTERM); 390 } 391 392 /* Log error and exit. */ 393 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 394 } 395 396 /* 397 * Signal handler for the key regeneration alarm. Note that this 398 * alarm only occurs in the daemon waiting for connections, and it does not 399 * do anything with the private key or random state before forking. 400 * Thus there should be no concurrency control/asynchronous execution 401 * problems. 402 */ 403 static void 404 generate_ephemeral_server_key(void) 405 { 406 verbose("Generating %s%d bit RSA key.", 407 sensitive_data.server_key ? "new " : "", options.server_key_bits); 408 if (sensitive_data.server_key != NULL) 409 key_free(sensitive_data.server_key); 410 sensitive_data.server_key = key_generate(KEY_RSA1, 411 options.server_key_bits); 412 verbose("RSA key generation complete."); 413 414 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 415 } 416 417 /*ARGSUSED*/ 418 static void 419 key_regeneration_alarm(int sig) 420 { 421 int save_errno = errno; 422 423 signal(SIGALRM, SIG_DFL); 424 errno = save_errno; 425 key_do_regen = 1; 426 } 427 428 static void 429 sshd_exchange_identification(int sock_in, int sock_out) 430 { 431 u_int i; 432 int mismatch; 433 int remote_major, remote_minor; 434 int major, minor; 435 char *s, *newline = "\n"; 436 char buf[256]; /* Must not be larger than remote_version. */ 437 char remote_version[256]; /* Must be at least as big as buf. */ 438 439 if ((options.protocol & SSH_PROTO_1) && 440 (options.protocol & SSH_PROTO_2)) { 441 major = PROTOCOL_MAJOR_1; 442 minor = 99; 443 } else if (options.protocol & SSH_PROTO_2) { 444 major = PROTOCOL_MAJOR_2; 445 minor = PROTOCOL_MINOR_2; 446 newline = "\r\n"; 447 } else { 448 major = PROTOCOL_MAJOR_1; 449 minor = PROTOCOL_MINOR_1; 450 } 451 452 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s", 453 major, minor, SSH_VERSION, 454 *options.version_addendum == '\0' ? "" : " ", 455 options.version_addendum, newline); 456 457 /* Send our protocol version identification. */ 458 if (roaming_atomicio(vwrite, sock_out, server_version_string, 459 strlen(server_version_string)) 460 != strlen(server_version_string)) { 461 logit("Could not write ident string to %s", get_remote_ipaddr()); 462 cleanup_exit(255); 463 } 464 465 /* Read other sides version identification. */ 466 memset(buf, 0, sizeof(buf)); 467 for (i = 0; i < sizeof(buf) - 1; i++) { 468 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 469 logit("Did not receive identification string from %s", 470 get_remote_ipaddr()); 471 cleanup_exit(255); 472 } 473 if (buf[i] == '\r') { 474 buf[i] = 0; 475 /* Kludge for F-Secure Macintosh < 1.0.2 */ 476 if (i == 12 && 477 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 478 break; 479 continue; 480 } 481 if (buf[i] == '\n') { 482 buf[i] = 0; 483 break; 484 } 485 } 486 buf[sizeof(buf) - 1] = 0; 487 client_version_string = xstrdup(buf); 488 489 /* 490 * Check that the versions match. In future this might accept 491 * several versions and set appropriate flags to handle them. 492 */ 493 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 494 &remote_major, &remote_minor, remote_version) != 3) { 495 s = "Protocol mismatch.\n"; 496 (void) atomicio(vwrite, sock_out, s, strlen(s)); 497 logit("Bad protocol version identification '%.100s' " 498 "from %s port %d", client_version_string, 499 get_remote_ipaddr(), get_remote_port()); 500 close(sock_in); 501 close(sock_out); 502 cleanup_exit(255); 503 } 504 debug("Client protocol version %d.%d; client software version %.100s", 505 remote_major, remote_minor, remote_version); 506 507 compat_datafellows(remote_version); 508 509 if ((datafellows & SSH_BUG_PROBE) != 0) { 510 logit("probed from %s with %s. Don't panic.", 511 get_remote_ipaddr(), client_version_string); 512 cleanup_exit(255); 513 } 514 if ((datafellows & SSH_BUG_SCANNER) != 0) { 515 logit("scanned from %s with %s. Don't panic.", 516 get_remote_ipaddr(), client_version_string); 517 cleanup_exit(255); 518 } 519 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) { 520 logit("Client version \"%.100s\" uses unsafe RSA signature " 521 "scheme; disabling use of RSA keys", remote_version); 522 } 523 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) { 524 fatal("Client version \"%.100s\" uses unsafe key agreement; " 525 "refusing connection", remote_version); 526 } 527 528 mismatch = 0; 529 switch (remote_major) { 530 case 1: 531 if (remote_minor == 99) { 532 if (options.protocol & SSH_PROTO_2) 533 enable_compat20(); 534 else 535 mismatch = 1; 536 break; 537 } 538 if (!(options.protocol & SSH_PROTO_1)) { 539 mismatch = 1; 540 break; 541 } 542 if (remote_minor < 3) { 543 packet_disconnect("Your ssh version is too old and " 544 "is no longer supported. Please install a newer version."); 545 } else if (remote_minor == 3) { 546 /* note that this disables agent-forwarding */ 547 enable_compat13(); 548 } 549 break; 550 case 2: 551 if (options.protocol & SSH_PROTO_2) { 552 enable_compat20(); 553 break; 554 } 555 /* FALLTHROUGH */ 556 default: 557 mismatch = 1; 558 break; 559 } 560 chop(server_version_string); 561 debug("Local version string %.200s", server_version_string); 562 563 if (mismatch) { 564 s = "Protocol major versions differ.\n"; 565 (void) atomicio(vwrite, sock_out, s, strlen(s)); 566 close(sock_in); 567 close(sock_out); 568 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 569 get_remote_ipaddr(), 570 server_version_string, client_version_string); 571 cleanup_exit(255); 572 } 573 } 574 575 /* Destroy the host and server keys. They will no longer be needed. */ 576 void 577 destroy_sensitive_data(void) 578 { 579 int i; 580 581 if (sensitive_data.server_key) { 582 key_free(sensitive_data.server_key); 583 sensitive_data.server_key = NULL; 584 } 585 for (i = 0; i < options.num_host_key_files; i++) { 586 if (sensitive_data.host_keys[i]) { 587 key_free(sensitive_data.host_keys[i]); 588 sensitive_data.host_keys[i] = NULL; 589 } 590 if (sensitive_data.host_certificates[i]) { 591 key_free(sensitive_data.host_certificates[i]); 592 sensitive_data.host_certificates[i] = NULL; 593 } 594 } 595 sensitive_data.ssh1_host_key = NULL; 596 explicit_bzero(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 597 } 598 599 /* Demote private to public keys for network child */ 600 void 601 demote_sensitive_data(void) 602 { 603 Key *tmp; 604 int i; 605 606 if (sensitive_data.server_key) { 607 tmp = key_demote(sensitive_data.server_key); 608 key_free(sensitive_data.server_key); 609 sensitive_data.server_key = tmp; 610 } 611 612 for (i = 0; i < options.num_host_key_files; i++) { 613 if (sensitive_data.host_keys[i]) { 614 tmp = key_demote(sensitive_data.host_keys[i]); 615 key_free(sensitive_data.host_keys[i]); 616 sensitive_data.host_keys[i] = tmp; 617 if (tmp->type == KEY_RSA1) 618 sensitive_data.ssh1_host_key = tmp; 619 } 620 /* Certs do not need demotion */ 621 } 622 623 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 624 } 625 626 static void 627 privsep_preauth_child(void) 628 { 629 u_int32_t rnd[256]; 630 gid_t gidset[1]; 631 632 /* Enable challenge-response authentication for privilege separation */ 633 privsep_challenge_enable(); 634 635 #ifdef GSSAPI 636 /* Cache supported mechanism OIDs for later use */ 637 if (options.gss_authentication) 638 ssh_gssapi_prepare_supported_oids(); 639 #endif 640 641 arc4random_stir(); 642 arc4random_buf(rnd, sizeof(rnd)); 643 RAND_seed(rnd, sizeof(rnd)); 644 explicit_bzero(rnd, sizeof(rnd)); 645 646 /* Demote the private keys to public keys. */ 647 demote_sensitive_data(); 648 649 /* Change our root directory */ 650 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 651 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 652 strerror(errno)); 653 if (chdir("/") == -1) 654 fatal("chdir(\"/\"): %s", strerror(errno)); 655 656 /* Drop our privileges */ 657 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 658 (u_int)privsep_pw->pw_gid); 659 #if 0 660 /* XXX not ready, too heavy after chroot */ 661 do_setusercontext(privsep_pw); 662 #else 663 gidset[0] = privsep_pw->pw_gid; 664 if (setgroups(1, gidset) < 0) 665 fatal("setgroups: %.100s", strerror(errno)); 666 permanently_set_uid(privsep_pw); 667 #endif 668 } 669 670 static int 671 privsep_preauth(Authctxt *authctxt) 672 { 673 int status; 674 pid_t pid; 675 struct ssh_sandbox *box = NULL; 676 677 /* Set up unprivileged child process to deal with network data */ 678 pmonitor = monitor_init(); 679 /* Store a pointer to the kex for later rekeying */ 680 pmonitor->m_pkex = &xxx_kex; 681 682 if (use_privsep == PRIVSEP_ON) 683 box = ssh_sandbox_init(pmonitor); 684 pid = fork(); 685 if (pid == -1) { 686 fatal("fork of unprivileged child failed"); 687 } else if (pid != 0) { 688 debug2("Network child is on pid %ld", (long)pid); 689 690 pmonitor->m_pid = pid; 691 if (have_agent) 692 auth_conn = ssh_get_authentication_connection(); 693 if (box != NULL) 694 ssh_sandbox_parent_preauth(box, pid); 695 monitor_child_preauth(authctxt, pmonitor); 696 697 /* Sync memory */ 698 monitor_sync(pmonitor); 699 700 /* Wait for the child's exit status */ 701 while (waitpid(pid, &status, 0) < 0) { 702 if (errno == EINTR) 703 continue; 704 pmonitor->m_pid = -1; 705 fatal("%s: waitpid: %s", __func__, strerror(errno)); 706 } 707 privsep_is_preauth = 0; 708 pmonitor->m_pid = -1; 709 if (WIFEXITED(status)) { 710 if (WEXITSTATUS(status) != 0) 711 fatal("%s: preauth child exited with status %d", 712 __func__, WEXITSTATUS(status)); 713 } else if (WIFSIGNALED(status)) 714 fatal("%s: preauth child terminated by signal %d", 715 __func__, WTERMSIG(status)); 716 if (box != NULL) 717 ssh_sandbox_parent_finish(box); 718 return 1; 719 } else { 720 /* child */ 721 close(pmonitor->m_sendfd); 722 close(pmonitor->m_log_recvfd); 723 724 /* Arrange for logging to be sent to the monitor */ 725 set_log_handler(mm_log_handler, pmonitor); 726 727 /* Demote the child */ 728 if (getuid() == 0 || geteuid() == 0) 729 privsep_preauth_child(); 730 setproctitle("%s", "[net]"); 731 if (box != NULL) 732 ssh_sandbox_child(box); 733 734 return 0; 735 } 736 } 737 738 static void 739 privsep_postauth(Authctxt *authctxt) 740 { 741 u_int32_t rnd[256]; 742 743 #ifdef DISABLE_FD_PASSING 744 if (1) { 745 #else 746 if (authctxt->pw->pw_uid == 0 || options.use_login) { 747 #endif 748 /* File descriptor passing is broken or root login */ 749 use_privsep = 0; 750 goto skip; 751 } 752 753 /* New socket pair */ 754 monitor_reinit(pmonitor); 755 756 pmonitor->m_pid = fork(); 757 if (pmonitor->m_pid == -1) 758 fatal("fork of unprivileged child failed"); 759 else if (pmonitor->m_pid != 0) { 760 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 761 buffer_clear(&loginmsg); 762 monitor_child_postauth(pmonitor); 763 764 /* NEVERREACHED */ 765 exit(0); 766 } 767 768 /* child */ 769 770 close(pmonitor->m_sendfd); 771 pmonitor->m_sendfd = -1; 772 773 /* Demote the private keys to public keys. */ 774 demote_sensitive_data(); 775 776 arc4random_stir(); 777 arc4random_buf(rnd, sizeof(rnd)); 778 RAND_seed(rnd, sizeof(rnd)); 779 explicit_bzero(rnd, sizeof(rnd)); 780 781 /* Drop privileges */ 782 do_setusercontext(authctxt->pw); 783 784 skip: 785 /* It is safe now to apply the key state */ 786 monitor_apply_keystate(pmonitor); 787 788 /* 789 * Tell the packet layer that authentication was successful, since 790 * this information is not part of the key state. 791 */ 792 packet_set_authenticated(); 793 } 794 795 static char * 796 list_hostkey_types(void) 797 { 798 Buffer b; 799 const char *p; 800 char *ret; 801 int i; 802 Key *key; 803 804 buffer_init(&b); 805 for (i = 0; i < options.num_host_key_files; i++) { 806 key = sensitive_data.host_keys[i]; 807 if (key == NULL) 808 key = sensitive_data.host_pubkeys[i]; 809 if (key == NULL) 810 continue; 811 switch (key->type) { 812 case KEY_RSA: 813 case KEY_DSA: 814 case KEY_ECDSA: 815 case KEY_ED25519: 816 if (buffer_len(&b) > 0) 817 buffer_append(&b, ",", 1); 818 p = key_ssh_name(key); 819 buffer_append(&b, p, strlen(p)); 820 break; 821 } 822 /* If the private key has a cert peer, then list that too */ 823 key = sensitive_data.host_certificates[i]; 824 if (key == NULL) 825 continue; 826 switch (key->type) { 827 case KEY_RSA_CERT_V00: 828 case KEY_DSA_CERT_V00: 829 case KEY_RSA_CERT: 830 case KEY_DSA_CERT: 831 case KEY_ECDSA_CERT: 832 case KEY_ED25519_CERT: 833 if (buffer_len(&b) > 0) 834 buffer_append(&b, ",", 1); 835 p = key_ssh_name(key); 836 buffer_append(&b, p, strlen(p)); 837 break; 838 } 839 } 840 buffer_append(&b, "\0", 1); 841 ret = xstrdup(buffer_ptr(&b)); 842 buffer_free(&b); 843 debug("list_hostkey_types: %s", ret); 844 return ret; 845 } 846 847 static Key * 848 get_hostkey_by_type(int type, int need_private) 849 { 850 int i; 851 Key *key; 852 853 for (i = 0; i < options.num_host_key_files; i++) { 854 switch (type) { 855 case KEY_RSA_CERT_V00: 856 case KEY_DSA_CERT_V00: 857 case KEY_RSA_CERT: 858 case KEY_DSA_CERT: 859 case KEY_ECDSA_CERT: 860 case KEY_ED25519_CERT: 861 key = sensitive_data.host_certificates[i]; 862 break; 863 default: 864 key = sensitive_data.host_keys[i]; 865 if (key == NULL && !need_private) 866 key = sensitive_data.host_pubkeys[i]; 867 break; 868 } 869 if (key != NULL && key->type == type) 870 return need_private ? 871 sensitive_data.host_keys[i] : key; 872 } 873 return NULL; 874 } 875 876 Key * 877 get_hostkey_public_by_type(int type) 878 { 879 return get_hostkey_by_type(type, 0); 880 } 881 882 Key * 883 get_hostkey_private_by_type(int type) 884 { 885 return get_hostkey_by_type(type, 1); 886 } 887 888 Key * 889 get_hostkey_by_index(int ind) 890 { 891 if (ind < 0 || ind >= options.num_host_key_files) 892 return (NULL); 893 return (sensitive_data.host_keys[ind]); 894 } 895 896 Key * 897 get_hostkey_public_by_index(int ind) 898 { 899 if (ind < 0 || ind >= options.num_host_key_files) 900 return (NULL); 901 return (sensitive_data.host_pubkeys[ind]); 902 } 903 904 int 905 get_hostkey_index(Key *key) 906 { 907 int i; 908 909 for (i = 0; i < options.num_host_key_files; i++) { 910 if (key_is_cert(key)) { 911 if (key == sensitive_data.host_certificates[i]) 912 return (i); 913 } else { 914 if (key == sensitive_data.host_keys[i]) 915 return (i); 916 if (key == sensitive_data.host_pubkeys[i]) 917 return (i); 918 } 919 } 920 return (-1); 921 } 922 923 /* 924 * returns 1 if connection should be dropped, 0 otherwise. 925 * dropping starts at connection #max_startups_begin with a probability 926 * of (max_startups_rate/100). the probability increases linearly until 927 * all connections are dropped for startups > max_startups 928 */ 929 static int 930 drop_connection(int startups) 931 { 932 int p, r; 933 934 if (startups < options.max_startups_begin) 935 return 0; 936 if (startups >= options.max_startups) 937 return 1; 938 if (options.max_startups_rate == 100) 939 return 1; 940 941 p = 100 - options.max_startups_rate; 942 p *= startups - options.max_startups_begin; 943 p /= options.max_startups - options.max_startups_begin; 944 p += options.max_startups_rate; 945 r = arc4random_uniform(100); 946 947 debug("drop_connection: p %d, r %d", p, r); 948 return (r < p) ? 1 : 0; 949 } 950 951 static void 952 usage(void) 953 { 954 if (options.version_addendum && *options.version_addendum != '\0') 955 fprintf(stderr, "%s %s, %s\n", 956 SSH_RELEASE, 957 options.version_addendum, OPENSSL_VERSION); 958 else 959 fprintf(stderr, "%s, %s\n", 960 SSH_RELEASE, OPENSSL_VERSION); 961 fprintf(stderr, 962 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 963 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 964 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port]\n" 965 " [-u len]\n" 966 ); 967 exit(1); 968 } 969 970 static void 971 send_rexec_state(int fd, Buffer *conf) 972 { 973 Buffer m; 974 975 debug3("%s: entering fd = %d config len %d", __func__, fd, 976 buffer_len(conf)); 977 978 /* 979 * Protocol from reexec master to child: 980 * string configuration 981 * u_int ephemeral_key_follows 982 * bignum e (only if ephemeral_key_follows == 1) 983 * bignum n " 984 * bignum d " 985 * bignum iqmp " 986 * bignum p " 987 * bignum q " 988 * string rngseed (only if OpenSSL is not self-seeded) 989 */ 990 buffer_init(&m); 991 buffer_put_cstring(&m, buffer_ptr(conf)); 992 993 #ifdef WITH_SSH1 994 if (sensitive_data.server_key != NULL && 995 sensitive_data.server_key->type == KEY_RSA1) { 996 buffer_put_int(&m, 1); 997 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 998 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 999 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 1000 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 1001 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 1002 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 1003 } else 1004 #endif 1005 buffer_put_int(&m, 0); 1006 1007 #ifndef OPENSSL_PRNG_ONLY 1008 rexec_send_rng_seed(&m); 1009 #endif 1010 1011 if (ssh_msg_send(fd, 0, &m) == -1) 1012 fatal("%s: ssh_msg_send failed", __func__); 1013 1014 buffer_free(&m); 1015 1016 debug3("%s: done", __func__); 1017 } 1018 1019 static void 1020 recv_rexec_state(int fd, Buffer *conf) 1021 { 1022 Buffer m; 1023 char *cp; 1024 u_int len; 1025 1026 debug3("%s: entering fd = %d", __func__, fd); 1027 1028 buffer_init(&m); 1029 1030 if (ssh_msg_recv(fd, &m) == -1) 1031 fatal("%s: ssh_msg_recv failed", __func__); 1032 if (buffer_get_char(&m) != 0) 1033 fatal("%s: rexec version mismatch", __func__); 1034 1035 cp = buffer_get_string(&m, &len); 1036 if (conf != NULL) 1037 buffer_append(conf, cp, len + 1); 1038 free(cp); 1039 1040 if (buffer_get_int(&m)) { 1041 #ifdef WITH_SSH1 1042 if (sensitive_data.server_key != NULL) 1043 key_free(sensitive_data.server_key); 1044 sensitive_data.server_key = key_new_private(KEY_RSA1); 1045 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 1046 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 1047 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 1048 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 1049 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 1050 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 1051 if (rsa_generate_additional_parameters( 1052 sensitive_data.server_key->rsa) != 0) 1053 fatal("%s: rsa_generate_additional_parameters " 1054 "error", __func__); 1055 #else 1056 fatal("ssh1 not supported"); 1057 #endif 1058 } 1059 1060 #ifndef OPENSSL_PRNG_ONLY 1061 rexec_recv_rng_seed(&m); 1062 #endif 1063 1064 buffer_free(&m); 1065 1066 debug3("%s: done", __func__); 1067 } 1068 1069 /* Accept a connection from inetd */ 1070 static void 1071 server_accept_inetd(int *sock_in, int *sock_out) 1072 { 1073 int fd; 1074 1075 startup_pipe = -1; 1076 if (rexeced_flag) { 1077 close(REEXEC_CONFIG_PASS_FD); 1078 *sock_in = *sock_out = dup(STDIN_FILENO); 1079 if (!debug_flag) { 1080 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1081 close(REEXEC_STARTUP_PIPE_FD); 1082 } 1083 } else { 1084 *sock_in = dup(STDIN_FILENO); 1085 *sock_out = dup(STDOUT_FILENO); 1086 } 1087 /* 1088 * We intentionally do not close the descriptors 0, 1, and 2 1089 * as our code for setting the descriptors won't work if 1090 * ttyfd happens to be one of those. 1091 */ 1092 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1093 dup2(fd, STDIN_FILENO); 1094 dup2(fd, STDOUT_FILENO); 1095 if (!log_stderr) 1096 dup2(fd, STDERR_FILENO); 1097 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1098 close(fd); 1099 } 1100 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1101 } 1102 1103 /* 1104 * Listen for TCP connections 1105 */ 1106 static void 1107 server_listen(void) 1108 { 1109 int ret, listen_sock, on = 1; 1110 struct addrinfo *ai; 1111 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1112 int socksize; 1113 socklen_t len; 1114 1115 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1116 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1117 continue; 1118 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1119 fatal("Too many listen sockets. " 1120 "Enlarge MAX_LISTEN_SOCKS"); 1121 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1122 ntop, sizeof(ntop), strport, sizeof(strport), 1123 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1124 error("getnameinfo failed: %.100s", 1125 ssh_gai_strerror(ret)); 1126 continue; 1127 } 1128 /* Create socket for listening. */ 1129 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1130 ai->ai_protocol); 1131 if (listen_sock < 0) { 1132 /* kernel may not support ipv6 */ 1133 verbose("socket: %.100s", strerror(errno)); 1134 continue; 1135 } 1136 if (set_nonblock(listen_sock) == -1) { 1137 close(listen_sock); 1138 continue; 1139 } 1140 /* 1141 * Set socket options. 1142 * Allow local port reuse in TIME_WAIT. 1143 */ 1144 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1145 &on, sizeof(on)) == -1) 1146 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1147 1148 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1149 if (ai->ai_family == AF_INET6) 1150 sock_set_v6only(listen_sock); 1151 1152 debug("Bind to port %s on %s.", strport, ntop); 1153 1154 len = sizeof(socksize); 1155 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len); 1156 debug("Server TCP RWIN socket size: %d", socksize); 1157 1158 /* Bind the socket to the desired port. */ 1159 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1160 error("Bind to port %s on %s failed: %.200s.", 1161 strport, ntop, strerror(errno)); 1162 close(listen_sock); 1163 continue; 1164 } 1165 listen_socks[num_listen_socks] = listen_sock; 1166 num_listen_socks++; 1167 1168 /* Start listening on the port. */ 1169 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1170 fatal("listen on [%s]:%s: %.100s", 1171 ntop, strport, strerror(errno)); 1172 logit("Server listening on %s port %s.", ntop, strport); 1173 } 1174 freeaddrinfo(options.listen_addrs); 1175 1176 if (!num_listen_socks) 1177 fatal("Cannot bind any address."); 1178 } 1179 1180 /* 1181 * The main TCP accept loop. Note that, for the non-debug case, returns 1182 * from this function are in a forked subprocess. 1183 */ 1184 static void 1185 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1186 { 1187 fd_set *fdset; 1188 int i, j, ret, maxfd; 1189 int key_used = 0, startups = 0; 1190 int startup_p[2] = { -1 , -1 }; 1191 struct sockaddr_storage from; 1192 socklen_t fromlen; 1193 pid_t pid; 1194 u_char rnd[256]; 1195 1196 /* setup fd set for accept */ 1197 fdset = NULL; 1198 maxfd = 0; 1199 for (i = 0; i < num_listen_socks; i++) 1200 if (listen_socks[i] > maxfd) 1201 maxfd = listen_socks[i]; 1202 /* pipes connected to unauthenticated childs */ 1203 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1204 for (i = 0; i < options.max_startups; i++) 1205 startup_pipes[i] = -1; 1206 1207 /* 1208 * Stay listening for connections until the system crashes or 1209 * the daemon is killed with a signal. 1210 */ 1211 for (;;) { 1212 if (received_sighup) 1213 sighup_restart(); 1214 if (fdset != NULL) 1215 free(fdset); 1216 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1217 sizeof(fd_mask)); 1218 1219 for (i = 0; i < num_listen_socks; i++) 1220 FD_SET(listen_socks[i], fdset); 1221 for (i = 0; i < options.max_startups; i++) 1222 if (startup_pipes[i] != -1) 1223 FD_SET(startup_pipes[i], fdset); 1224 1225 /* Wait in select until there is a connection. */ 1226 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1227 if (ret < 0 && errno != EINTR) 1228 error("select: %.100s", strerror(errno)); 1229 if (received_sigterm) { 1230 logit("Received signal %d; terminating.", 1231 (int) received_sigterm); 1232 close_listen_socks(); 1233 unlink(options.pid_file); 1234 exit(received_sigterm == SIGTERM ? 0 : 255); 1235 } 1236 if (key_used && key_do_regen) { 1237 generate_ephemeral_server_key(); 1238 key_used = 0; 1239 key_do_regen = 0; 1240 } 1241 if (ret < 0) 1242 continue; 1243 1244 for (i = 0; i < options.max_startups; i++) 1245 if (startup_pipes[i] != -1 && 1246 FD_ISSET(startup_pipes[i], fdset)) { 1247 /* 1248 * the read end of the pipe is ready 1249 * if the child has closed the pipe 1250 * after successful authentication 1251 * or if the child has died 1252 */ 1253 close(startup_pipes[i]); 1254 startup_pipes[i] = -1; 1255 startups--; 1256 } 1257 for (i = 0; i < num_listen_socks; i++) { 1258 if (!FD_ISSET(listen_socks[i], fdset)) 1259 continue; 1260 fromlen = sizeof(from); 1261 *newsock = accept(listen_socks[i], 1262 (struct sockaddr *)&from, &fromlen); 1263 if (*newsock < 0) { 1264 if (errno != EINTR && errno != EWOULDBLOCK && 1265 errno != ECONNABORTED && errno != EAGAIN) 1266 error("accept: %.100s", 1267 strerror(errno)); 1268 if (errno == EMFILE || errno == ENFILE) 1269 usleep(100 * 1000); 1270 continue; 1271 } 1272 if (unset_nonblock(*newsock) == -1) { 1273 close(*newsock); 1274 continue; 1275 } 1276 if (drop_connection(startups) == 1) { 1277 debug("drop connection #%d", startups); 1278 close(*newsock); 1279 continue; 1280 } 1281 if (pipe(startup_p) == -1) { 1282 close(*newsock); 1283 continue; 1284 } 1285 1286 if (rexec_flag && socketpair(AF_UNIX, 1287 SOCK_STREAM, 0, config_s) == -1) { 1288 error("reexec socketpair: %s", 1289 strerror(errno)); 1290 close(*newsock); 1291 close(startup_p[0]); 1292 close(startup_p[1]); 1293 continue; 1294 } 1295 1296 for (j = 0; j < options.max_startups; j++) 1297 if (startup_pipes[j] == -1) { 1298 startup_pipes[j] = startup_p[0]; 1299 if (maxfd < startup_p[0]) 1300 maxfd = startup_p[0]; 1301 startups++; 1302 break; 1303 } 1304 1305 /* 1306 * Got connection. Fork a child to handle it, unless 1307 * we are in debugging mode. 1308 */ 1309 if (debug_flag) { 1310 /* 1311 * In debugging mode. Close the listening 1312 * socket, and start processing the 1313 * connection without forking. 1314 */ 1315 debug("Server will not fork when running in debugging mode."); 1316 close_listen_socks(); 1317 *sock_in = *newsock; 1318 *sock_out = *newsock; 1319 close(startup_p[0]); 1320 close(startup_p[1]); 1321 startup_pipe = -1; 1322 pid = getpid(); 1323 if (rexec_flag) { 1324 send_rexec_state(config_s[0], 1325 &cfg); 1326 close(config_s[0]); 1327 } 1328 break; 1329 } 1330 1331 /* 1332 * Normal production daemon. Fork, and have 1333 * the child process the connection. The 1334 * parent continues listening. 1335 */ 1336 platform_pre_fork(); 1337 if ((pid = fork()) == 0) { 1338 /* 1339 * Child. Close the listening and 1340 * max_startup sockets. Start using 1341 * the accepted socket. Reinitialize 1342 * logging (since our pid has changed). 1343 * We break out of the loop to handle 1344 * the connection. 1345 */ 1346 platform_post_fork_child(); 1347 startup_pipe = startup_p[1]; 1348 close_startup_pipes(); 1349 close_listen_socks(); 1350 *sock_in = *newsock; 1351 *sock_out = *newsock; 1352 log_init(__progname, 1353 options.log_level, 1354 options.log_facility, 1355 log_stderr); 1356 if (rexec_flag) 1357 close(config_s[0]); 1358 break; 1359 } 1360 1361 /* Parent. Stay in the loop. */ 1362 platform_post_fork_parent(pid); 1363 if (pid < 0) 1364 error("fork: %.100s", strerror(errno)); 1365 else 1366 debug("Forked child %ld.", (long)pid); 1367 1368 close(startup_p[1]); 1369 1370 if (rexec_flag) { 1371 send_rexec_state(config_s[0], &cfg); 1372 close(config_s[0]); 1373 close(config_s[1]); 1374 } 1375 1376 /* 1377 * Mark that the key has been used (it 1378 * was "given" to the child). 1379 */ 1380 if ((options.protocol & SSH_PROTO_1) && 1381 key_used == 0) { 1382 /* Schedule server key regeneration alarm. */ 1383 signal(SIGALRM, key_regeneration_alarm); 1384 alarm(options.key_regeneration_time); 1385 key_used = 1; 1386 } 1387 1388 close(*newsock); 1389 1390 /* 1391 * Ensure that our random state differs 1392 * from that of the child 1393 */ 1394 arc4random_stir(); 1395 arc4random_buf(rnd, sizeof(rnd)); 1396 RAND_seed(rnd, sizeof(rnd)); 1397 explicit_bzero(rnd, sizeof(rnd)); 1398 } 1399 1400 /* child process check (or debug mode) */ 1401 if (num_listen_socks < 0) 1402 break; 1403 } 1404 } 1405 1406 1407 /* 1408 * Main program for the daemon. 1409 */ 1410 int 1411 main(int ac, char **av) 1412 { 1413 extern char *optarg; 1414 extern int optind; 1415 int opt, i, j, on = 1; 1416 int sock_in = -1, sock_out = -1, newsock = -1; 1417 const char *remote_ip; 1418 int remote_port; 1419 char *line, *logfile = NULL; 1420 int config_s[2] = { -1 , -1 }; 1421 u_int n; 1422 u_int64_t ibytes, obytes; 1423 mode_t new_umask; 1424 Key *key; 1425 Key *pubkey; 1426 int keytype; 1427 Authctxt *authctxt; 1428 struct connection_info *connection_info = get_connection_info(0, 0); 1429 1430 #ifdef HAVE_SECUREWARE 1431 (void)set_auth_parameters(ac, av); 1432 #endif 1433 __progname = ssh_get_progname(av[0]); 1434 1435 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1436 saved_argc = ac; 1437 rexec_argc = ac; 1438 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1439 for (i = 0; i < ac; i++) 1440 saved_argv[i] = xstrdup(av[i]); 1441 saved_argv[i] = NULL; 1442 1443 #ifndef HAVE_SETPROCTITLE 1444 /* Prepare for later setproctitle emulation */ 1445 compat_init_setproctitle(ac, av); 1446 av = saved_argv; 1447 #endif 1448 1449 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1450 debug("setgroups(): %.200s", strerror(errno)); 1451 1452 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1453 sanitise_stdfd(); 1454 1455 /* Initialize configuration options to their default values. */ 1456 initialize_server_options(&options); 1457 1458 /* Parse command-line arguments. */ 1459 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeE:iqrtQRT46")) != -1) { 1460 switch (opt) { 1461 case '4': 1462 options.address_family = AF_INET; 1463 break; 1464 case '6': 1465 options.address_family = AF_INET6; 1466 break; 1467 case 'f': 1468 config_file_name = optarg; 1469 break; 1470 case 'c': 1471 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1472 fprintf(stderr, "too many host certificates.\n"); 1473 exit(1); 1474 } 1475 options.host_cert_files[options.num_host_cert_files++] = 1476 derelativise_path(optarg); 1477 break; 1478 case 'd': 1479 if (debug_flag == 0) { 1480 debug_flag = 1; 1481 options.log_level = SYSLOG_LEVEL_DEBUG1; 1482 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1483 options.log_level++; 1484 break; 1485 case 'D': 1486 no_daemon_flag = 1; 1487 break; 1488 case 'E': 1489 logfile = xstrdup(optarg); 1490 /* FALLTHROUGH */ 1491 case 'e': 1492 log_stderr = 1; 1493 break; 1494 case 'i': 1495 inetd_flag = 1; 1496 break; 1497 case 'r': 1498 rexec_flag = 0; 1499 break; 1500 case 'R': 1501 rexeced_flag = 1; 1502 inetd_flag = 1; 1503 break; 1504 case 'Q': 1505 /* ignored */ 1506 break; 1507 case 'q': 1508 options.log_level = SYSLOG_LEVEL_QUIET; 1509 break; 1510 case 'b': 1511 options.server_key_bits = (int)strtonum(optarg, 256, 1512 32768, NULL); 1513 break; 1514 case 'p': 1515 options.ports_from_cmdline = 1; 1516 if (options.num_ports >= MAX_PORTS) { 1517 fprintf(stderr, "too many ports.\n"); 1518 exit(1); 1519 } 1520 options.ports[options.num_ports++] = a2port(optarg); 1521 if (options.ports[options.num_ports-1] <= 0) { 1522 fprintf(stderr, "Bad port number.\n"); 1523 exit(1); 1524 } 1525 break; 1526 case 'g': 1527 if ((options.login_grace_time = convtime(optarg)) == -1) { 1528 fprintf(stderr, "Invalid login grace time.\n"); 1529 exit(1); 1530 } 1531 break; 1532 case 'k': 1533 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1534 fprintf(stderr, "Invalid key regeneration interval.\n"); 1535 exit(1); 1536 } 1537 break; 1538 case 'h': 1539 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1540 fprintf(stderr, "too many host keys.\n"); 1541 exit(1); 1542 } 1543 options.host_key_files[options.num_host_key_files++] = 1544 derelativise_path(optarg); 1545 break; 1546 case 't': 1547 test_flag = 1; 1548 break; 1549 case 'T': 1550 test_flag = 2; 1551 break; 1552 case 'C': 1553 if (parse_server_match_testspec(connection_info, 1554 optarg) == -1) 1555 exit(1); 1556 break; 1557 case 'u': 1558 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1559 if (utmp_len > MAXHOSTNAMELEN) { 1560 fprintf(stderr, "Invalid utmp length.\n"); 1561 exit(1); 1562 } 1563 break; 1564 case 'o': 1565 line = xstrdup(optarg); 1566 if (process_server_config_line(&options, line, 1567 "command-line", 0, NULL, NULL) != 0) 1568 exit(1); 1569 free(line); 1570 break; 1571 case '?': 1572 default: 1573 usage(); 1574 break; 1575 } 1576 } 1577 if (rexeced_flag || inetd_flag) 1578 rexec_flag = 0; 1579 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1580 fatal("sshd re-exec requires execution with an absolute path"); 1581 if (rexeced_flag) 1582 closefrom(REEXEC_MIN_FREE_FD); 1583 else 1584 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1585 1586 #ifdef WITH_OPENSSL 1587 OpenSSL_add_all_algorithms(); 1588 #endif 1589 1590 /* If requested, redirect the logs to the specified logfile. */ 1591 if (logfile != NULL) { 1592 log_redirect_stderr_to(logfile); 1593 free(logfile); 1594 } 1595 /* 1596 * Force logging to stderr until we have loaded the private host 1597 * key (unless started from inetd) 1598 */ 1599 log_init(__progname, 1600 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1601 SYSLOG_LEVEL_INFO : options.log_level, 1602 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1603 SYSLOG_FACILITY_AUTH : options.log_facility, 1604 log_stderr || !inetd_flag); 1605 1606 /* 1607 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1608 * root's environment 1609 */ 1610 if (getenv("KRB5CCNAME") != NULL) 1611 (void) unsetenv("KRB5CCNAME"); 1612 1613 #ifdef _UNICOS 1614 /* Cray can define user privs drop all privs now! 1615 * Not needed on PRIV_SU systems! 1616 */ 1617 drop_cray_privs(); 1618 #endif 1619 1620 sensitive_data.server_key = NULL; 1621 sensitive_data.ssh1_host_key = NULL; 1622 sensitive_data.have_ssh1_key = 0; 1623 sensitive_data.have_ssh2_key = 0; 1624 1625 /* 1626 * If we're doing an extended config test, make sure we have all of 1627 * the parameters we need. If we're not doing an extended test, 1628 * do not silently ignore connection test params. 1629 */ 1630 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0) 1631 fatal("user, host and addr are all required when testing " 1632 "Match configs"); 1633 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0) 1634 fatal("Config test connection parameter (-C) provided without " 1635 "test mode (-T)"); 1636 1637 /* Fetch our configuration */ 1638 buffer_init(&cfg); 1639 if (rexeced_flag) 1640 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1641 else 1642 load_server_config(config_file_name, &cfg); 1643 1644 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1645 &cfg, NULL); 1646 1647 seed_rng(); 1648 1649 /* Fill in default values for those options not explicitly set. */ 1650 fill_default_server_options(&options); 1651 1652 /* challenge-response is implemented via keyboard interactive */ 1653 if (options.challenge_response_authentication) 1654 options.kbd_interactive_authentication = 1; 1655 1656 /* Check that options are sensible */ 1657 if (options.authorized_keys_command_user == NULL && 1658 (options.authorized_keys_command != NULL && 1659 strcasecmp(options.authorized_keys_command, "none") != 0)) 1660 fatal("AuthorizedKeysCommand set without " 1661 "AuthorizedKeysCommandUser"); 1662 1663 /* 1664 * Check whether there is any path through configured auth methods. 1665 * Unfortunately it is not possible to verify this generally before 1666 * daemonisation in the presence of Match block, but this catches 1667 * and warns for trivial misconfigurations that could break login. 1668 */ 1669 if (options.num_auth_methods != 0) { 1670 if ((options.protocol & SSH_PROTO_1)) 1671 fatal("AuthenticationMethods is not supported with " 1672 "SSH protocol 1"); 1673 for (n = 0; n < options.num_auth_methods; n++) { 1674 if (auth2_methods_valid(options.auth_methods[n], 1675 1) == 0) 1676 break; 1677 } 1678 if (n >= options.num_auth_methods) 1679 fatal("AuthenticationMethods cannot be satisfied by " 1680 "enabled authentication methods"); 1681 } 1682 1683 /* set default channel AF */ 1684 channel_set_af(options.address_family); 1685 1686 /* Check that there are no remaining arguments. */ 1687 if (optind < ac) { 1688 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1689 exit(1); 1690 } 1691 1692 debug("sshd version %s, %s", SSH_VERSION, 1693 #ifdef WITH_OPENSSL 1694 SSLeay_version(SSLEAY_VERSION) 1695 #else 1696 "without OpenSSL" 1697 #endif 1698 ); 1699 1700 /* Store privilege separation user for later use if required. */ 1701 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1702 if (use_privsep || options.kerberos_authentication) 1703 fatal("Privilege separation user %s does not exist", 1704 SSH_PRIVSEP_USER); 1705 } else { 1706 explicit_bzero(privsep_pw->pw_passwd, 1707 strlen(privsep_pw->pw_passwd)); 1708 privsep_pw = pwcopy(privsep_pw); 1709 free(privsep_pw->pw_passwd); 1710 privsep_pw->pw_passwd = xstrdup("*"); 1711 } 1712 endpwent(); 1713 1714 /* load host keys */ 1715 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1716 sizeof(Key *)); 1717 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1718 sizeof(Key *)); 1719 for (i = 0; i < options.num_host_key_files; i++) { 1720 sensitive_data.host_keys[i] = NULL; 1721 sensitive_data.host_pubkeys[i] = NULL; 1722 } 1723 1724 if (options.host_key_agent) { 1725 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1726 setenv(SSH_AUTHSOCKET_ENV_NAME, 1727 options.host_key_agent, 1); 1728 have_agent = ssh_agent_present(); 1729 } 1730 1731 for (i = 0; i < options.num_host_key_files; i++) { 1732 key = key_load_private(options.host_key_files[i], "", NULL); 1733 pubkey = key_load_public(options.host_key_files[i], NULL); 1734 sensitive_data.host_keys[i] = key; 1735 sensitive_data.host_pubkeys[i] = pubkey; 1736 1737 if (key == NULL && pubkey != NULL && pubkey->type != KEY_RSA1 && 1738 have_agent) { 1739 debug("will rely on agent for hostkey %s", 1740 options.host_key_files[i]); 1741 keytype = pubkey->type; 1742 } else if (key != NULL) { 1743 keytype = key->type; 1744 } else { 1745 error("Could not load host key: %s", 1746 options.host_key_files[i]); 1747 sensitive_data.host_keys[i] = NULL; 1748 sensitive_data.host_pubkeys[i] = NULL; 1749 continue; 1750 } 1751 1752 switch (keytype) { 1753 case KEY_RSA1: 1754 sensitive_data.ssh1_host_key = key; 1755 sensitive_data.have_ssh1_key = 1; 1756 break; 1757 case KEY_RSA: 1758 case KEY_DSA: 1759 case KEY_ECDSA: 1760 case KEY_ED25519: 1761 sensitive_data.have_ssh2_key = 1; 1762 break; 1763 } 1764 debug("private host key: #%d type %d %s", i, keytype, 1765 key_type(key ? key : pubkey)); 1766 } 1767 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1768 logit("Disabling protocol version 1. Could not load host key"); 1769 options.protocol &= ~SSH_PROTO_1; 1770 } 1771 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1772 logit("Disabling protocol version 2. Could not load host key"); 1773 options.protocol &= ~SSH_PROTO_2; 1774 } 1775 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1776 logit("sshd: no hostkeys available -- exiting."); 1777 exit(1); 1778 } 1779 1780 /* 1781 * Load certificates. They are stored in an array at identical 1782 * indices to the public keys that they relate to. 1783 */ 1784 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1785 sizeof(Key *)); 1786 for (i = 0; i < options.num_host_key_files; i++) 1787 sensitive_data.host_certificates[i] = NULL; 1788 1789 for (i = 0; i < options.num_host_cert_files; i++) { 1790 key = key_load_public(options.host_cert_files[i], NULL); 1791 if (key == NULL) { 1792 error("Could not load host certificate: %s", 1793 options.host_cert_files[i]); 1794 continue; 1795 } 1796 if (!key_is_cert(key)) { 1797 error("Certificate file is not a certificate: %s", 1798 options.host_cert_files[i]); 1799 key_free(key); 1800 continue; 1801 } 1802 /* Find matching private key */ 1803 for (j = 0; j < options.num_host_key_files; j++) { 1804 if (key_equal_public(key, 1805 sensitive_data.host_keys[j])) { 1806 sensitive_data.host_certificates[j] = key; 1807 break; 1808 } 1809 } 1810 if (j >= options.num_host_key_files) { 1811 error("No matching private key for certificate: %s", 1812 options.host_cert_files[i]); 1813 key_free(key); 1814 continue; 1815 } 1816 sensitive_data.host_certificates[j] = key; 1817 debug("host certificate: #%d type %d %s", j, key->type, 1818 key_type(key)); 1819 } 1820 1821 #ifdef WITH_SSH1 1822 /* Check certain values for sanity. */ 1823 if (options.protocol & SSH_PROTO_1) { 1824 if (options.server_key_bits < 512 || 1825 options.server_key_bits > 32768) { 1826 fprintf(stderr, "Bad server key size.\n"); 1827 exit(1); 1828 } 1829 /* 1830 * Check that server and host key lengths differ sufficiently. This 1831 * is necessary to make double encryption work with rsaref. Oh, I 1832 * hate software patents. I dont know if this can go? Niels 1833 */ 1834 if (options.server_key_bits > 1835 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1836 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1837 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1838 SSH_KEY_BITS_RESERVED) { 1839 options.server_key_bits = 1840 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1841 SSH_KEY_BITS_RESERVED; 1842 debug("Forcing server key to %d bits to make it differ from host key.", 1843 options.server_key_bits); 1844 } 1845 } 1846 #endif 1847 1848 if (use_privsep) { 1849 struct stat st; 1850 1851 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1852 (S_ISDIR(st.st_mode) == 0)) 1853 fatal("Missing privilege separation directory: %s", 1854 _PATH_PRIVSEP_CHROOT_DIR); 1855 1856 #ifdef HAVE_CYGWIN 1857 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1858 (st.st_uid != getuid () || 1859 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1860 #else 1861 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1862 #endif 1863 fatal("%s must be owned by root and not group or " 1864 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1865 } 1866 1867 if (test_flag > 1) { 1868 if (server_match_spec_complete(connection_info) == 1) 1869 parse_server_match_config(&options, connection_info); 1870 dump_config(&options); 1871 } 1872 1873 /* Configuration looks good, so exit if in test mode. */ 1874 if (test_flag) 1875 exit(0); 1876 1877 /* 1878 * Clear out any supplemental groups we may have inherited. This 1879 * prevents inadvertent creation of files with bad modes (in the 1880 * portable version at least, it's certainly possible for PAM 1881 * to create a file, and we can't control the code in every 1882 * module which might be used). 1883 */ 1884 if (setgroups(0, NULL) < 0) 1885 debug("setgroups() failed: %.200s", strerror(errno)); 1886 1887 if (rexec_flag) { 1888 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1889 for (i = 0; i < rexec_argc; i++) { 1890 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1891 rexec_argv[i] = saved_argv[i]; 1892 } 1893 rexec_argv[rexec_argc] = "-R"; 1894 rexec_argv[rexec_argc + 1] = NULL; 1895 } 1896 1897 /* Ensure that umask disallows at least group and world write */ 1898 new_umask = umask(0077) | 0022; 1899 (void) umask(new_umask); 1900 1901 /* Initialize the log (it is reinitialized below in case we forked). */ 1902 if (debug_flag && (!inetd_flag || rexeced_flag)) 1903 log_stderr = 1; 1904 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1905 1906 /* 1907 * If not in debugging mode, and not started from inetd, disconnect 1908 * from the controlling terminal, and fork. The original process 1909 * exits. 1910 */ 1911 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1912 #ifdef TIOCNOTTY 1913 int fd; 1914 #endif /* TIOCNOTTY */ 1915 if (daemon(0, 0) < 0) 1916 fatal("daemon() failed: %.200s", strerror(errno)); 1917 1918 /* Disconnect from the controlling tty. */ 1919 #ifdef TIOCNOTTY 1920 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1921 if (fd >= 0) { 1922 (void) ioctl(fd, TIOCNOTTY, NULL); 1923 close(fd); 1924 } 1925 #endif /* TIOCNOTTY */ 1926 } 1927 /* Reinitialize the log (because of the fork above). */ 1928 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1929 1930 /* Avoid killing the process in high-pressure swapping environments. */ 1931 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 1932 debug("madvise(): %.200s", strerror(errno)); 1933 1934 /* Chdir to the root directory so that the current disk can be 1935 unmounted if desired. */ 1936 if (chdir("/") == -1) 1937 error("chdir(\"/\"): %s", strerror(errno)); 1938 1939 /* ignore SIGPIPE */ 1940 signal(SIGPIPE, SIG_IGN); 1941 1942 /* Get a connection, either from inetd or a listening TCP socket */ 1943 if (inetd_flag) { 1944 server_accept_inetd(&sock_in, &sock_out); 1945 } else { 1946 platform_pre_listen(); 1947 server_listen(); 1948 1949 if (options.protocol & SSH_PROTO_1) 1950 generate_ephemeral_server_key(); 1951 1952 signal(SIGHUP, sighup_handler); 1953 signal(SIGCHLD, main_sigchld_handler); 1954 signal(SIGTERM, sigterm_handler); 1955 signal(SIGQUIT, sigterm_handler); 1956 1957 /* 1958 * Write out the pid file after the sigterm handler 1959 * is setup and the listen sockets are bound 1960 */ 1961 if (!debug_flag) { 1962 FILE *f = fopen(options.pid_file, "w"); 1963 1964 if (f == NULL) { 1965 error("Couldn't create pid file \"%s\": %s", 1966 options.pid_file, strerror(errno)); 1967 } else { 1968 fprintf(f, "%ld\n", (long) getpid()); 1969 fclose(f); 1970 } 1971 } 1972 1973 /* Accept a connection and return in a forked child */ 1974 server_accept_loop(&sock_in, &sock_out, 1975 &newsock, config_s); 1976 } 1977 1978 /* This is the child processing a new connection. */ 1979 setproctitle("%s", "[accepted]"); 1980 1981 /* 1982 * Create a new session and process group since the 4.4BSD 1983 * setlogin() affects the entire process group. We don't 1984 * want the child to be able to affect the parent. 1985 */ 1986 #if !defined(SSHD_ACQUIRES_CTTY) 1987 /* 1988 * If setsid is called, on some platforms sshd will later acquire a 1989 * controlling terminal which will result in "could not set 1990 * controlling tty" errors. 1991 */ 1992 if (!debug_flag && !inetd_flag && setsid() < 0) 1993 error("setsid: %.100s", strerror(errno)); 1994 #endif 1995 1996 if (rexec_flag) { 1997 int fd; 1998 1999 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 2000 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2001 dup2(newsock, STDIN_FILENO); 2002 dup2(STDIN_FILENO, STDOUT_FILENO); 2003 if (startup_pipe == -1) 2004 close(REEXEC_STARTUP_PIPE_FD); 2005 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 2006 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 2007 close(startup_pipe); 2008 startup_pipe = REEXEC_STARTUP_PIPE_FD; 2009 } 2010 2011 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 2012 close(config_s[1]); 2013 2014 execv(rexec_argv[0], rexec_argv); 2015 2016 /* Reexec has failed, fall back and continue */ 2017 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 2018 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 2019 log_init(__progname, options.log_level, 2020 options.log_facility, log_stderr); 2021 2022 /* Clean up fds */ 2023 close(REEXEC_CONFIG_PASS_FD); 2024 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2025 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 2026 dup2(fd, STDIN_FILENO); 2027 dup2(fd, STDOUT_FILENO); 2028 if (fd > STDERR_FILENO) 2029 close(fd); 2030 } 2031 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2032 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2033 } 2034 2035 /* Executed child processes don't need these. */ 2036 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2037 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2038 2039 /* 2040 * Disable the key regeneration alarm. We will not regenerate the 2041 * key since we are no longer in a position to give it to anyone. We 2042 * will not restart on SIGHUP since it no longer makes sense. 2043 */ 2044 alarm(0); 2045 signal(SIGALRM, SIG_DFL); 2046 signal(SIGHUP, SIG_DFL); 2047 signal(SIGTERM, SIG_DFL); 2048 signal(SIGQUIT, SIG_DFL); 2049 signal(SIGCHLD, SIG_DFL); 2050 signal(SIGINT, SIG_DFL); 2051 2052 #ifdef __FreeBSD__ 2053 /* 2054 * Initialize the resolver. This may not happen automatically 2055 * before privsep chroot(). 2056 */ 2057 if ((_res.options & RES_INIT) == 0) { 2058 debug("res_init()"); 2059 res_init(); 2060 } 2061 #ifdef GSSAPI 2062 /* 2063 * Force GSS-API to parse its configuration and load any 2064 * mechanism plugins. 2065 */ 2066 { 2067 gss_OID_set mechs; 2068 OM_uint32 minor_status; 2069 gss_indicate_mechs(&minor_status, &mechs); 2070 gss_release_oid_set(&minor_status, &mechs); 2071 } 2072 #endif 2073 #endif 2074 2075 /* 2076 * Register our connection. This turns encryption off because we do 2077 * not have a key. 2078 */ 2079 packet_set_connection(sock_in, sock_out); 2080 packet_set_server(); 2081 2082 /* Set SO_KEEPALIVE if requested. */ 2083 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 2084 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 2085 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2086 2087 if ((remote_port = get_remote_port()) < 0) { 2088 debug("get_remote_port failed"); 2089 cleanup_exit(255); 2090 } 2091 2092 /* 2093 * We use get_canonical_hostname with usedns = 0 instead of 2094 * get_remote_ipaddr here so IP options will be checked. 2095 */ 2096 (void) get_canonical_hostname(0); 2097 /* 2098 * The rest of the code depends on the fact that 2099 * get_remote_ipaddr() caches the remote ip, even if 2100 * the socket goes away. 2101 */ 2102 remote_ip = get_remote_ipaddr(); 2103 2104 #ifdef SSH_AUDIT_EVENTS 2105 audit_connection_from(remote_ip, remote_port); 2106 #endif 2107 #ifdef LIBWRAP 2108 allow_severity = options.log_facility|LOG_INFO; 2109 deny_severity = options.log_facility|LOG_WARNING; 2110 /* Check whether logins are denied from this host. */ 2111 if (packet_connection_is_on_socket()) { 2112 struct request_info req; 2113 2114 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 2115 fromhost(&req); 2116 2117 if (!hosts_access(&req)) { 2118 debug("Connection refused by tcp wrapper"); 2119 refuse(&req); 2120 /* NOTREACHED */ 2121 fatal("libwrap refuse returns"); 2122 } 2123 } 2124 #endif /* LIBWRAP */ 2125 2126 /* Log the connection. */ 2127 verbose("Connection from %s port %d on %s port %d", 2128 remote_ip, remote_port, 2129 get_local_ipaddr(sock_in), get_local_port()); 2130 2131 /* 2132 * We don't want to listen forever unless the other side 2133 * successfully authenticates itself. So we set up an alarm which is 2134 * cleared after successful authentication. A limit of zero 2135 * indicates no limit. Note that we don't set the alarm in debugging 2136 * mode; it is just annoying to have the server exit just when you 2137 * are about to discover the bug. 2138 */ 2139 signal(SIGALRM, grace_alarm_handler); 2140 if (!debug_flag) 2141 alarm(options.login_grace_time); 2142 2143 sshd_exchange_identification(sock_in, sock_out); 2144 2145 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 2146 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 2147 generate_ephemeral_server_key(); 2148 2149 packet_set_nonblocking(); 2150 2151 /* allocate authentication context */ 2152 authctxt = xcalloc(1, sizeof(*authctxt)); 2153 2154 authctxt->loginmsg = &loginmsg; 2155 2156 /* XXX global for cleanup, access from other modules */ 2157 the_authctxt = authctxt; 2158 2159 /* prepare buffer to collect messages to display to user after login */ 2160 buffer_init(&loginmsg); 2161 auth_debug_reset(); 2162 2163 if (use_privsep) { 2164 if (privsep_preauth(authctxt) == 1) 2165 goto authenticated; 2166 } else if (compat20 && have_agent) 2167 auth_conn = ssh_get_authentication_connection(); 2168 2169 /* perform the key exchange */ 2170 /* authenticate user and start session */ 2171 if (compat20) { 2172 do_ssh2_kex(); 2173 do_authentication2(authctxt); 2174 } else { 2175 #ifdef WITH_SSH1 2176 do_ssh1_kex(); 2177 do_authentication(authctxt); 2178 #else 2179 fatal("ssh1 not supported"); 2180 #endif 2181 } 2182 /* 2183 * If we use privilege separation, the unprivileged child transfers 2184 * the current keystate and exits 2185 */ 2186 if (use_privsep) { 2187 mm_send_keystate(pmonitor); 2188 exit(0); 2189 } 2190 2191 authenticated: 2192 /* 2193 * Cancel the alarm we set to limit the time taken for 2194 * authentication. 2195 */ 2196 alarm(0); 2197 signal(SIGALRM, SIG_DFL); 2198 authctxt->authenticated = 1; 2199 if (startup_pipe != -1) { 2200 close(startup_pipe); 2201 startup_pipe = -1; 2202 } 2203 2204 #ifdef SSH_AUDIT_EVENTS 2205 audit_event(SSH_AUTH_SUCCESS); 2206 #endif 2207 2208 #ifdef GSSAPI 2209 if (options.gss_authentication) { 2210 temporarily_use_uid(authctxt->pw); 2211 ssh_gssapi_storecreds(); 2212 restore_uid(); 2213 } 2214 #endif 2215 #ifdef USE_PAM 2216 if (options.use_pam) { 2217 do_pam_setcred(1); 2218 do_pam_session(); 2219 } 2220 #endif 2221 2222 /* 2223 * In privilege separation, we fork another child and prepare 2224 * file descriptor passing. 2225 */ 2226 if (use_privsep) { 2227 privsep_postauth(authctxt); 2228 /* the monitor process [priv] will not return */ 2229 if (!compat20) 2230 destroy_sensitive_data(); 2231 } 2232 2233 packet_set_timeout(options.client_alive_interval, 2234 options.client_alive_count_max); 2235 2236 /* Start session. */ 2237 do_authenticated(authctxt); 2238 2239 /* The connection has been terminated. */ 2240 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 2241 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 2242 verbose("Transferred: sent %llu, received %llu bytes", 2243 (unsigned long long)obytes, (unsigned long long)ibytes); 2244 2245 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2246 2247 #ifdef USE_PAM 2248 if (options.use_pam) 2249 finish_pam(); 2250 #endif /* USE_PAM */ 2251 2252 #ifdef SSH_AUDIT_EVENTS 2253 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2254 #endif 2255 2256 packet_close(); 2257 2258 if (use_privsep) 2259 mm_terminate(); 2260 2261 exit(0); 2262 } 2263 2264 #ifdef WITH_SSH1 2265 /* 2266 * Decrypt session_key_int using our private server key and private host key 2267 * (key with larger modulus first). 2268 */ 2269 int 2270 ssh1_session_key(BIGNUM *session_key_int) 2271 { 2272 int rsafail = 0; 2273 2274 if (BN_cmp(sensitive_data.server_key->rsa->n, 2275 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2276 /* Server key has bigger modulus. */ 2277 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2278 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2279 SSH_KEY_BITS_RESERVED) { 2280 fatal("do_connection: %s: " 2281 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2282 get_remote_ipaddr(), 2283 BN_num_bits(sensitive_data.server_key->rsa->n), 2284 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2285 SSH_KEY_BITS_RESERVED); 2286 } 2287 if (rsa_private_decrypt(session_key_int, session_key_int, 2288 sensitive_data.server_key->rsa) != 0) 2289 rsafail++; 2290 if (rsa_private_decrypt(session_key_int, session_key_int, 2291 sensitive_data.ssh1_host_key->rsa) != 0) 2292 rsafail++; 2293 } else { 2294 /* Host key has bigger modulus (or they are equal). */ 2295 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2296 BN_num_bits(sensitive_data.server_key->rsa->n) + 2297 SSH_KEY_BITS_RESERVED) { 2298 fatal("do_connection: %s: " 2299 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2300 get_remote_ipaddr(), 2301 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2302 BN_num_bits(sensitive_data.server_key->rsa->n), 2303 SSH_KEY_BITS_RESERVED); 2304 } 2305 if (rsa_private_decrypt(session_key_int, session_key_int, 2306 sensitive_data.ssh1_host_key->rsa) != 0) 2307 rsafail++; 2308 if (rsa_private_decrypt(session_key_int, session_key_int, 2309 sensitive_data.server_key->rsa) != 0) 2310 rsafail++; 2311 } 2312 return (rsafail); 2313 } 2314 2315 /* 2316 * SSH1 key exchange 2317 */ 2318 static void 2319 do_ssh1_kex(void) 2320 { 2321 int i, len; 2322 int rsafail = 0; 2323 BIGNUM *session_key_int; 2324 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2325 u_char cookie[8]; 2326 u_int cipher_type, auth_mask, protocol_flags; 2327 2328 /* 2329 * Generate check bytes that the client must send back in the user 2330 * packet in order for it to be accepted; this is used to defy ip 2331 * spoofing attacks. Note that this only works against somebody 2332 * doing IP spoofing from a remote machine; any machine on the local 2333 * network can still see outgoing packets and catch the random 2334 * cookie. This only affects rhosts authentication, and this is one 2335 * of the reasons why it is inherently insecure. 2336 */ 2337 arc4random_buf(cookie, sizeof(cookie)); 2338 2339 /* 2340 * Send our public key. We include in the packet 64 bits of random 2341 * data that must be matched in the reply in order to prevent IP 2342 * spoofing. 2343 */ 2344 packet_start(SSH_SMSG_PUBLIC_KEY); 2345 for (i = 0; i < 8; i++) 2346 packet_put_char(cookie[i]); 2347 2348 /* Store our public server RSA key. */ 2349 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2350 packet_put_bignum(sensitive_data.server_key->rsa->e); 2351 packet_put_bignum(sensitive_data.server_key->rsa->n); 2352 2353 /* Store our public host RSA key. */ 2354 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2355 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2356 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2357 2358 /* Put protocol flags. */ 2359 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2360 2361 /* Declare which ciphers we support. */ 2362 packet_put_int(cipher_mask_ssh1(0)); 2363 2364 /* Declare supported authentication types. */ 2365 auth_mask = 0; 2366 if (options.rhosts_rsa_authentication) 2367 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2368 if (options.rsa_authentication) 2369 auth_mask |= 1 << SSH_AUTH_RSA; 2370 if (options.challenge_response_authentication == 1) 2371 auth_mask |= 1 << SSH_AUTH_TIS; 2372 if (options.password_authentication) 2373 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2374 packet_put_int(auth_mask); 2375 2376 /* Send the packet and wait for it to be sent. */ 2377 packet_send(); 2378 packet_write_wait(); 2379 2380 debug("Sent %d bit server key and %d bit host key.", 2381 BN_num_bits(sensitive_data.server_key->rsa->n), 2382 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2383 2384 /* Read clients reply (cipher type and session key). */ 2385 packet_read_expect(SSH_CMSG_SESSION_KEY); 2386 2387 /* Get cipher type and check whether we accept this. */ 2388 cipher_type = packet_get_char(); 2389 2390 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2391 packet_disconnect("Warning: client selects unsupported cipher."); 2392 2393 /* Get check bytes from the packet. These must match those we 2394 sent earlier with the public key packet. */ 2395 for (i = 0; i < 8; i++) 2396 if (cookie[i] != packet_get_char()) 2397 packet_disconnect("IP Spoofing check bytes do not match."); 2398 2399 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2400 2401 /* Get the encrypted integer. */ 2402 if ((session_key_int = BN_new()) == NULL) 2403 fatal("do_ssh1_kex: BN_new failed"); 2404 packet_get_bignum(session_key_int); 2405 2406 protocol_flags = packet_get_int(); 2407 packet_set_protocol_flags(protocol_flags); 2408 packet_check_eom(); 2409 2410 /* Decrypt session_key_int using host/server keys */ 2411 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2412 2413 /* 2414 * Extract session key from the decrypted integer. The key is in the 2415 * least significant 256 bits of the integer; the first byte of the 2416 * key is in the highest bits. 2417 */ 2418 if (!rsafail) { 2419 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2420 len = BN_num_bytes(session_key_int); 2421 if (len < 0 || (u_int)len > sizeof(session_key)) { 2422 error("do_ssh1_kex: bad session key len from %s: " 2423 "session_key_int %d > sizeof(session_key) %lu", 2424 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2425 rsafail++; 2426 } else { 2427 explicit_bzero(session_key, sizeof(session_key)); 2428 BN_bn2bin(session_key_int, 2429 session_key + sizeof(session_key) - len); 2430 2431 derive_ssh1_session_id( 2432 sensitive_data.ssh1_host_key->rsa->n, 2433 sensitive_data.server_key->rsa->n, 2434 cookie, session_id); 2435 /* 2436 * Xor the first 16 bytes of the session key with the 2437 * session id. 2438 */ 2439 for (i = 0; i < 16; i++) 2440 session_key[i] ^= session_id[i]; 2441 } 2442 } 2443 if (rsafail) { 2444 int bytes = BN_num_bytes(session_key_int); 2445 u_char *buf = xmalloc(bytes); 2446 struct ssh_digest_ctx *md; 2447 2448 logit("do_connection: generating a fake encryption key"); 2449 BN_bn2bin(session_key_int, buf); 2450 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || 2451 ssh_digest_update(md, buf, bytes) < 0 || 2452 ssh_digest_update(md, sensitive_data.ssh1_cookie, 2453 SSH_SESSION_KEY_LENGTH) < 0 || 2454 ssh_digest_final(md, session_key, sizeof(session_key)) < 0) 2455 fatal("%s: md5 failed", __func__); 2456 ssh_digest_free(md); 2457 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || 2458 ssh_digest_update(md, session_key, 16) < 0 || 2459 ssh_digest_update(md, sensitive_data.ssh1_cookie, 2460 SSH_SESSION_KEY_LENGTH) < 0 || 2461 ssh_digest_final(md, session_key + 16, 2462 sizeof(session_key) - 16) < 0) 2463 fatal("%s: md5 failed", __func__); 2464 ssh_digest_free(md); 2465 explicit_bzero(buf, bytes); 2466 free(buf); 2467 for (i = 0; i < 16; i++) 2468 session_id[i] = session_key[i] ^ session_key[i + 16]; 2469 } 2470 /* Destroy the private and public keys. No longer. */ 2471 destroy_sensitive_data(); 2472 2473 if (use_privsep) 2474 mm_ssh1_session_id(session_id); 2475 2476 /* Destroy the decrypted integer. It is no longer needed. */ 2477 BN_clear_free(session_key_int); 2478 2479 /* Set the session key. From this on all communications will be encrypted. */ 2480 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2481 2482 /* Destroy our copy of the session key. It is no longer needed. */ 2483 explicit_bzero(session_key, sizeof(session_key)); 2484 2485 debug("Received session key; encryption turned on."); 2486 2487 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2488 packet_start(SSH_SMSG_SUCCESS); 2489 packet_send(); 2490 packet_write_wait(); 2491 } 2492 #endif 2493 2494 void 2495 sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, u_int *slen, 2496 u_char *data, u_int dlen) 2497 { 2498 if (privkey) { 2499 if (PRIVSEP(key_sign(privkey, signature, slen, data, dlen) < 0)) 2500 fatal("%s: key_sign failed", __func__); 2501 } else if (use_privsep) { 2502 if (mm_key_sign(pubkey, signature, slen, data, dlen) < 0) 2503 fatal("%s: pubkey_sign failed", __func__); 2504 } else { 2505 if (ssh_agent_sign(auth_conn, pubkey, signature, slen, data, 2506 dlen)) 2507 fatal("%s: ssh_agent_sign failed", __func__); 2508 } 2509 } 2510 2511 /* 2512 * SSH2 key exchange: diffie-hellman-group1-sha1 2513 */ 2514 static void 2515 do_ssh2_kex(void) 2516 { 2517 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2518 Kex *kex; 2519 2520 if (options.ciphers != NULL) { 2521 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2522 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2523 } 2524 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2525 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2526 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2527 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2528 2529 if (options.macs != NULL) { 2530 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2531 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2532 } 2533 if (options.compression == COMP_NONE) { 2534 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2535 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2536 } else if (options.compression == COMP_DELAYED) { 2537 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2538 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2539 } 2540 if (options.kex_algorithms != NULL) 2541 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 2542 2543 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2544 myproposal[PROPOSAL_KEX_ALGS]); 2545 2546 if (options.rekey_limit || options.rekey_interval) 2547 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 2548 (time_t)options.rekey_interval); 2549 2550 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2551 list_hostkey_types()); 2552 2553 /* start key exchange */ 2554 kex = kex_setup(myproposal); 2555 #ifdef WITH_OPENSSL 2556 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2557 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2558 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2559 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2560 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2561 #endif 2562 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2563 kex->server = 1; 2564 kex->client_version_string=client_version_string; 2565 kex->server_version_string=server_version_string; 2566 kex->load_host_public_key=&get_hostkey_public_by_type; 2567 kex->load_host_private_key=&get_hostkey_private_by_type; 2568 kex->host_key_index=&get_hostkey_index; 2569 kex->sign = sshd_hostkey_sign; 2570 2571 xxx_kex = kex; 2572 2573 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2574 2575 session_id2 = kex->session_id; 2576 session_id2_len = kex->session_id_len; 2577 2578 #ifdef DEBUG_KEXDH 2579 /* send 1st encrypted/maced/compressed message */ 2580 packet_start(SSH2_MSG_IGNORE); 2581 packet_put_cstring("markus"); 2582 packet_send(); 2583 packet_write_wait(); 2584 #endif 2585 debug("KEX done"); 2586 } 2587 2588 /* server specific fatal cleanup */ 2589 void 2590 cleanup_exit(int i) 2591 { 2592 if (the_authctxt) { 2593 do_cleanup(the_authctxt); 2594 if (use_privsep && privsep_is_preauth && 2595 pmonitor != NULL && pmonitor->m_pid > 1) { 2596 debug("Killing privsep child %d", pmonitor->m_pid); 2597 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2598 errno != ESRCH) 2599 error("%s: kill(%d): %s", __func__, 2600 pmonitor->m_pid, strerror(errno)); 2601 } 2602 } 2603 #ifdef SSH_AUDIT_EVENTS 2604 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2605 if (!use_privsep || mm_is_monitor()) 2606 audit_event(SSH_CONNECTION_ABANDON); 2607 #endif 2608 _exit(i); 2609 } 2610