1 /* $OpenBSD: sshd.c,v 1.420 2014/02/26 21:53:37 markus 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/rand.h> 81 #include "openbsd-compat/openssl-compat.h" 82 83 #ifdef HAVE_SECUREWARE 84 #include <sys/security.h> 85 #include <prot.h> 86 #endif 87 88 #ifdef __FreeBSD__ 89 #include <resolv.h> 90 #if defined(GSSAPI) && defined(HAVE_GSSAPI_GSSAPI_H) 91 #include <gssapi/gssapi.h> 92 #elif defined(GSSAPI) && defined(HAVE_GSSAPI_H) 93 #include <gssapi.h> 94 #endif 95 #endif 96 97 #include "xmalloc.h" 98 #include "ssh.h" 99 #include "ssh1.h" 100 #include "ssh2.h" 101 #include "rsa.h" 102 #include "sshpty.h" 103 #include "packet.h" 104 #include "log.h" 105 #include "buffer.h" 106 #include "servconf.h" 107 #include "uidswap.h" 108 #include "compat.h" 109 #include "cipher.h" 110 #include "digest.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 "authfd.h" 122 #include "misc.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 static void do_ssh1_kex(void); 279 static void do_ssh2_kex(void); 280 281 /* 282 * Close all listening sockets 283 */ 284 static void 285 close_listen_socks(void) 286 { 287 int i; 288 289 for (i = 0; i < num_listen_socks; i++) 290 close(listen_socks[i]); 291 num_listen_socks = -1; 292 } 293 294 static void 295 close_startup_pipes(void) 296 { 297 int i; 298 299 if (startup_pipes) 300 for (i = 0; i < options.max_startups; i++) 301 if (startup_pipes[i] != -1) 302 close(startup_pipes[i]); 303 } 304 305 /* 306 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 307 * the effect is to reread the configuration file (and to regenerate 308 * the server key). 309 */ 310 311 /*ARGSUSED*/ 312 static void 313 sighup_handler(int sig) 314 { 315 int save_errno = errno; 316 317 received_sighup = 1; 318 signal(SIGHUP, sighup_handler); 319 errno = save_errno; 320 } 321 322 /* 323 * Called from the main program after receiving SIGHUP. 324 * Restarts the server. 325 */ 326 static void 327 sighup_restart(void) 328 { 329 logit("Received SIGHUP; restarting."); 330 platform_pre_restart(); 331 close_listen_socks(); 332 close_startup_pipes(); 333 alarm(0); /* alarm timer persists across exec */ 334 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 335 execv(saved_argv[0], saved_argv); 336 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 337 strerror(errno)); 338 exit(1); 339 } 340 341 /* 342 * Generic signal handler for terminating signals in the master daemon. 343 */ 344 /*ARGSUSED*/ 345 static void 346 sigterm_handler(int sig) 347 { 348 received_sigterm = sig; 349 } 350 351 /* 352 * SIGCHLD handler. This is called whenever a child dies. This will then 353 * reap any zombies left by exited children. 354 */ 355 /*ARGSUSED*/ 356 static void 357 main_sigchld_handler(int sig) 358 { 359 int save_errno = errno; 360 pid_t pid; 361 int status; 362 363 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 364 (pid < 0 && errno == EINTR)) 365 ; 366 367 signal(SIGCHLD, main_sigchld_handler); 368 errno = save_errno; 369 } 370 371 /* 372 * Signal handler for the alarm after the login grace period has expired. 373 */ 374 /*ARGSUSED*/ 375 static void 376 grace_alarm_handler(int sig) 377 { 378 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 379 kill(pmonitor->m_pid, SIGALRM); 380 381 /* 382 * Try to kill any processes that we have spawned, E.g. authorized 383 * keys command helpers. 384 */ 385 if (getpgid(0) == getpid()) { 386 signal(SIGTERM, SIG_IGN); 387 kill(0, SIGTERM); 388 } 389 390 /* Log error and exit. */ 391 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 392 } 393 394 /* 395 * Signal handler for the key regeneration alarm. Note that this 396 * alarm only occurs in the daemon waiting for connections, and it does not 397 * do anything with the private key or random state before forking. 398 * Thus there should be no concurrency control/asynchronous execution 399 * problems. 400 */ 401 static void 402 generate_ephemeral_server_key(void) 403 { 404 verbose("Generating %s%d bit RSA key.", 405 sensitive_data.server_key ? "new " : "", options.server_key_bits); 406 if (sensitive_data.server_key != NULL) 407 key_free(sensitive_data.server_key); 408 sensitive_data.server_key = key_generate(KEY_RSA1, 409 options.server_key_bits); 410 verbose("RSA key generation complete."); 411 412 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 413 } 414 415 /*ARGSUSED*/ 416 static void 417 key_regeneration_alarm(int sig) 418 { 419 int save_errno = errno; 420 421 signal(SIGALRM, SIG_DFL); 422 errno = save_errno; 423 key_do_regen = 1; 424 } 425 426 static void 427 sshd_exchange_identification(int sock_in, int sock_out) 428 { 429 u_int i; 430 int mismatch; 431 int remote_major, remote_minor; 432 int major, minor; 433 char *s, *newline = "\n"; 434 char buf[256]; /* Must not be larger than remote_version. */ 435 char remote_version[256]; /* Must be at least as big as buf. */ 436 437 if ((options.protocol & SSH_PROTO_1) && 438 (options.protocol & SSH_PROTO_2)) { 439 major = PROTOCOL_MAJOR_1; 440 minor = 99; 441 } else if (options.protocol & SSH_PROTO_2) { 442 major = PROTOCOL_MAJOR_2; 443 minor = PROTOCOL_MINOR_2; 444 newline = "\r\n"; 445 } else { 446 major = PROTOCOL_MAJOR_1; 447 minor = PROTOCOL_MINOR_1; 448 } 449 450 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s%s", 451 major, minor, SSH_VERSION, 452 options.hpn_disabled ? "" : SSH_VERSION_HPN, 453 *options.version_addendum == '\0' ? "" : " ", 454 options.version_addendum, newline); 455 456 /* Send our protocol version identification. */ 457 if (roaming_atomicio(vwrite, sock_out, server_version_string, 458 strlen(server_version_string)) 459 != strlen(server_version_string)) { 460 logit("Could not write ident string to %s", get_remote_ipaddr()); 461 cleanup_exit(255); 462 } 463 464 /* Read other sides version identification. */ 465 memset(buf, 0, sizeof(buf)); 466 for (i = 0; i < sizeof(buf) - 1; i++) { 467 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 468 logit("Did not receive identification string from %s", 469 get_remote_ipaddr()); 470 cleanup_exit(255); 471 } 472 if (buf[i] == '\r') { 473 buf[i] = 0; 474 /* Kludge for F-Secure Macintosh < 1.0.2 */ 475 if (i == 12 && 476 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 477 break; 478 continue; 479 } 480 if (buf[i] == '\n') { 481 buf[i] = 0; 482 break; 483 } 484 } 485 buf[sizeof(buf) - 1] = 0; 486 client_version_string = xstrdup(buf); 487 488 /* 489 * Check that the versions match. In future this might accept 490 * several versions and set appropriate flags to handle them. 491 */ 492 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 493 &remote_major, &remote_minor, remote_version) != 3) { 494 s = "Protocol mismatch.\n"; 495 (void) atomicio(vwrite, sock_out, s, strlen(s)); 496 logit("Bad protocol version identification '%.100s' " 497 "from %s port %d", client_version_string, 498 get_remote_ipaddr(), get_remote_port()); 499 close(sock_in); 500 close(sock_out); 501 cleanup_exit(255); 502 } 503 debug("Client protocol version %d.%d; client software version %.100s", 504 remote_major, remote_minor, remote_version); 505 506 compat_datafellows(remote_version); 507 508 if ((datafellows & SSH_BUG_PROBE) != 0) { 509 logit("probed from %s with %s. Don't panic.", 510 get_remote_ipaddr(), client_version_string); 511 cleanup_exit(255); 512 } 513 if ((datafellows & SSH_BUG_SCANNER) != 0) { 514 logit("scanned from %s with %s. Don't panic.", 515 get_remote_ipaddr(), client_version_string); 516 cleanup_exit(255); 517 } 518 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) { 519 logit("Client version \"%.100s\" uses unsafe RSA signature " 520 "scheme; disabling use of RSA keys", remote_version); 521 } 522 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) { 523 fatal("Client version \"%.100s\" uses unsafe key agreement; " 524 "refusing connection", remote_version); 525 } 526 527 mismatch = 0; 528 switch (remote_major) { 529 case 1: 530 if (remote_minor == 99) { 531 if (options.protocol & SSH_PROTO_2) 532 enable_compat20(); 533 else 534 mismatch = 1; 535 break; 536 } 537 if (!(options.protocol & SSH_PROTO_1)) { 538 mismatch = 1; 539 break; 540 } 541 if (remote_minor < 3) { 542 packet_disconnect("Your ssh version is too old and " 543 "is no longer supported. Please install a newer version."); 544 } else if (remote_minor == 3) { 545 /* note that this disables agent-forwarding */ 546 enable_compat13(); 547 } 548 break; 549 case 2: 550 if (options.protocol & SSH_PROTO_2) { 551 enable_compat20(); 552 break; 553 } 554 /* FALLTHROUGH */ 555 default: 556 mismatch = 1; 557 break; 558 } 559 chop(server_version_string); 560 debug("Local version string %.200s", server_version_string); 561 562 if (mismatch) { 563 s = "Protocol major versions differ.\n"; 564 (void) atomicio(vwrite, sock_out, s, strlen(s)); 565 close(sock_in); 566 close(sock_out); 567 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 568 get_remote_ipaddr(), 569 server_version_string, client_version_string); 570 cleanup_exit(255); 571 } 572 } 573 574 /* Destroy the host and server keys. They will no longer be needed. */ 575 void 576 destroy_sensitive_data(void) 577 { 578 int i; 579 580 if (sensitive_data.server_key) { 581 key_free(sensitive_data.server_key); 582 sensitive_data.server_key = NULL; 583 } 584 for (i = 0; i < options.num_host_key_files; i++) { 585 if (sensitive_data.host_keys[i]) { 586 key_free(sensitive_data.host_keys[i]); 587 sensitive_data.host_keys[i] = NULL; 588 } 589 if (sensitive_data.host_certificates[i]) { 590 key_free(sensitive_data.host_certificates[i]); 591 sensitive_data.host_certificates[i] = NULL; 592 } 593 } 594 sensitive_data.ssh1_host_key = NULL; 595 explicit_bzero(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 596 } 597 598 /* Demote private to public keys for network child */ 599 void 600 demote_sensitive_data(void) 601 { 602 Key *tmp; 603 int i; 604 605 if (sensitive_data.server_key) { 606 tmp = key_demote(sensitive_data.server_key); 607 key_free(sensitive_data.server_key); 608 sensitive_data.server_key = tmp; 609 } 610 611 for (i = 0; i < options.num_host_key_files; i++) { 612 if (sensitive_data.host_keys[i]) { 613 tmp = key_demote(sensitive_data.host_keys[i]); 614 key_free(sensitive_data.host_keys[i]); 615 sensitive_data.host_keys[i] = tmp; 616 if (tmp->type == KEY_RSA1) 617 sensitive_data.ssh1_host_key = tmp; 618 } 619 /* Certs do not need demotion */ 620 } 621 622 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 623 } 624 625 static void 626 privsep_preauth_child(void) 627 { 628 u_int32_t rnd[256]; 629 gid_t gidset[1]; 630 631 /* Enable challenge-response authentication for privilege separation */ 632 privsep_challenge_enable(); 633 634 #ifdef GSSAPI 635 /* Cache supported mechanism OIDs for later use */ 636 if (options.gss_authentication) 637 ssh_gssapi_prepare_supported_oids(); 638 #endif 639 640 arc4random_stir(); 641 arc4random_buf(rnd, sizeof(rnd)); 642 RAND_seed(rnd, sizeof(rnd)); 643 explicit_bzero(rnd, sizeof(rnd)); 644 645 /* Demote the private keys to public keys. */ 646 demote_sensitive_data(); 647 648 /* Change our root directory */ 649 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 650 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 651 strerror(errno)); 652 if (chdir("/") == -1) 653 fatal("chdir(\"/\"): %s", strerror(errno)); 654 655 /* Drop our privileges */ 656 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 657 (u_int)privsep_pw->pw_gid); 658 #if 0 659 /* XXX not ready, too heavy after chroot */ 660 do_setusercontext(privsep_pw); 661 #else 662 gidset[0] = privsep_pw->pw_gid; 663 if (setgroups(1, gidset) < 0) 664 fatal("setgroups: %.100s", strerror(errno)); 665 permanently_set_uid(privsep_pw); 666 #endif 667 } 668 669 static int 670 privsep_preauth(Authctxt *authctxt) 671 { 672 int status; 673 pid_t pid; 674 struct ssh_sandbox *box = NULL; 675 676 /* Set up unprivileged child process to deal with network data */ 677 pmonitor = monitor_init(); 678 /* Store a pointer to the kex for later rekeying */ 679 pmonitor->m_pkex = &xxx_kex; 680 681 if (use_privsep == PRIVSEP_ON) 682 box = ssh_sandbox_init(pmonitor); 683 pid = fork(); 684 if (pid == -1) { 685 fatal("fork of unprivileged child failed"); 686 } else if (pid != 0) { 687 debug2("Network child is on pid %ld", (long)pid); 688 689 pmonitor->m_pid = pid; 690 if (have_agent) 691 auth_conn = ssh_get_authentication_connection(); 692 if (box != NULL) 693 ssh_sandbox_parent_preauth(box, pid); 694 monitor_child_preauth(authctxt, pmonitor); 695 696 /* Sync memory */ 697 monitor_sync(pmonitor); 698 699 /* Wait for the child's exit status */ 700 while (waitpid(pid, &status, 0) < 0) { 701 if (errno == EINTR) 702 continue; 703 pmonitor->m_pid = -1; 704 fatal("%s: waitpid: %s", __func__, strerror(errno)); 705 } 706 privsep_is_preauth = 0; 707 pmonitor->m_pid = -1; 708 if (WIFEXITED(status)) { 709 if (WEXITSTATUS(status) != 0) 710 fatal("%s: preauth child exited with status %d", 711 __func__, WEXITSTATUS(status)); 712 } else if (WIFSIGNALED(status)) 713 fatal("%s: preauth child terminated by signal %d", 714 __func__, WTERMSIG(status)); 715 if (box != NULL) 716 ssh_sandbox_parent_finish(box); 717 return 1; 718 } else { 719 /* child */ 720 close(pmonitor->m_sendfd); 721 close(pmonitor->m_log_recvfd); 722 723 /* Arrange for logging to be sent to the monitor */ 724 set_log_handler(mm_log_handler, pmonitor); 725 726 /* Demote the child */ 727 if (getuid() == 0 || geteuid() == 0) 728 privsep_preauth_child(); 729 setproctitle("%s", "[net]"); 730 if (box != NULL) 731 ssh_sandbox_child(box); 732 733 return 0; 734 } 735 } 736 737 static void 738 privsep_postauth(Authctxt *authctxt) 739 { 740 u_int32_t rnd[256]; 741 742 #ifdef DISABLE_FD_PASSING 743 if (1) { 744 #else 745 if (authctxt->pw->pw_uid == 0 || options.use_login) { 746 #endif 747 /* File descriptor passing is broken or root login */ 748 use_privsep = 0; 749 goto skip; 750 } 751 752 /* New socket pair */ 753 monitor_reinit(pmonitor); 754 755 pmonitor->m_pid = fork(); 756 if (pmonitor->m_pid == -1) 757 fatal("fork of unprivileged child failed"); 758 else if (pmonitor->m_pid != 0) { 759 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 760 buffer_clear(&loginmsg); 761 monitor_child_postauth(pmonitor); 762 763 /* NEVERREACHED */ 764 exit(0); 765 } 766 767 /* child */ 768 769 close(pmonitor->m_sendfd); 770 pmonitor->m_sendfd = -1; 771 772 /* Demote the private keys to public keys. */ 773 demote_sensitive_data(); 774 775 arc4random_stir(); 776 arc4random_buf(rnd, sizeof(rnd)); 777 RAND_seed(rnd, sizeof(rnd)); 778 explicit_bzero(rnd, sizeof(rnd)); 779 780 /* Drop privileges */ 781 do_setusercontext(authctxt->pw); 782 783 skip: 784 /* It is safe now to apply the key state */ 785 monitor_apply_keystate(pmonitor); 786 787 /* 788 * Tell the packet layer that authentication was successful, since 789 * this information is not part of the key state. 790 */ 791 packet_set_authenticated(); 792 } 793 794 static char * 795 list_hostkey_types(void) 796 { 797 Buffer b; 798 const char *p; 799 char *ret; 800 int i; 801 Key *key; 802 803 buffer_init(&b); 804 for (i = 0; i < options.num_host_key_files; i++) { 805 key = sensitive_data.host_keys[i]; 806 if (key == NULL) 807 key = sensitive_data.host_pubkeys[i]; 808 if (key == NULL) 809 continue; 810 switch (key->type) { 811 case KEY_RSA: 812 case KEY_DSA: 813 case KEY_ECDSA: 814 case KEY_ED25519: 815 if (buffer_len(&b) > 0) 816 buffer_append(&b, ",", 1); 817 p = key_ssh_name(key); 818 buffer_append(&b, p, strlen(p)); 819 break; 820 } 821 /* If the private key has a cert peer, then list that too */ 822 key = sensitive_data.host_certificates[i]; 823 if (key == NULL) 824 continue; 825 switch (key->type) { 826 case KEY_RSA_CERT_V00: 827 case KEY_DSA_CERT_V00: 828 case KEY_RSA_CERT: 829 case KEY_DSA_CERT: 830 case KEY_ECDSA_CERT: 831 case KEY_ED25519_CERT: 832 if (buffer_len(&b) > 0) 833 buffer_append(&b, ",", 1); 834 p = key_ssh_name(key); 835 buffer_append(&b, p, strlen(p)); 836 break; 837 } 838 } 839 buffer_append(&b, "\0", 1); 840 ret = xstrdup(buffer_ptr(&b)); 841 buffer_free(&b); 842 debug("list_hostkey_types: %s", ret); 843 return ret; 844 } 845 846 static Key * 847 get_hostkey_by_type(int type, int need_private) 848 { 849 int i; 850 Key *key; 851 852 for (i = 0; i < options.num_host_key_files; i++) { 853 switch (type) { 854 case KEY_RSA_CERT_V00: 855 case KEY_DSA_CERT_V00: 856 case KEY_RSA_CERT: 857 case KEY_DSA_CERT: 858 case KEY_ECDSA_CERT: 859 case KEY_ED25519_CERT: 860 key = sensitive_data.host_certificates[i]; 861 break; 862 default: 863 key = sensitive_data.host_keys[i]; 864 if (key == NULL && !need_private) 865 key = sensitive_data.host_pubkeys[i]; 866 break; 867 } 868 if (key != NULL && key->type == type) 869 return need_private ? 870 sensitive_data.host_keys[i] : key; 871 } 872 return NULL; 873 } 874 875 Key * 876 get_hostkey_public_by_type(int type) 877 { 878 return get_hostkey_by_type(type, 0); 879 } 880 881 Key * 882 get_hostkey_private_by_type(int type) 883 { 884 return get_hostkey_by_type(type, 1); 885 } 886 887 Key * 888 get_hostkey_by_index(int ind) 889 { 890 if (ind < 0 || ind >= options.num_host_key_files) 891 return (NULL); 892 return (sensitive_data.host_keys[ind]); 893 } 894 895 Key * 896 get_hostkey_public_by_index(int ind) 897 { 898 if (ind < 0 || ind >= options.num_host_key_files) 899 return (NULL); 900 return (sensitive_data.host_pubkeys[ind]); 901 } 902 903 int 904 get_hostkey_index(Key *key) 905 { 906 int i; 907 908 for (i = 0; i < options.num_host_key_files; i++) { 909 if (key_is_cert(key)) { 910 if (key == sensitive_data.host_certificates[i]) 911 return (i); 912 } else { 913 if (key == sensitive_data.host_keys[i]) 914 return (i); 915 if (key == sensitive_data.host_pubkeys[i]) 916 return (i); 917 } 918 } 919 return (-1); 920 } 921 922 /* 923 * returns 1 if connection should be dropped, 0 otherwise. 924 * dropping starts at connection #max_startups_begin with a probability 925 * of (max_startups_rate/100). the probability increases linearly until 926 * all connections are dropped for startups > max_startups 927 */ 928 static int 929 drop_connection(int startups) 930 { 931 int p, r; 932 933 if (startups < options.max_startups_begin) 934 return 0; 935 if (startups >= options.max_startups) 936 return 1; 937 if (options.max_startups_rate == 100) 938 return 1; 939 940 p = 100 - options.max_startups_rate; 941 p *= startups - options.max_startups_begin; 942 p /= options.max_startups - options.max_startups_begin; 943 p += options.max_startups_rate; 944 r = arc4random_uniform(100); 945 946 debug("drop_connection: p %d, r %d", p, r); 947 return (r < p) ? 1 : 0; 948 } 949 950 static void 951 usage(void) 952 { 953 if (options.version_addendum && *options.version_addendum != '\0') 954 fprintf(stderr, "%s%s %s, %s\n", 955 SSH_RELEASE, options.hpn_disabled ? "" : SSH_VERSION_HPN, 956 options.version_addendum, SSLeay_version(SSLEAY_VERSION)); 957 else 958 fprintf(stderr, "%s%s, %s\n", 959 SSH_RELEASE, options.hpn_disabled ? "" : SSH_VERSION_HPN, 960 SSLeay_version(SSLEAY_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 if (sensitive_data.server_key != NULL && 994 sensitive_data.server_key->type == KEY_RSA1) { 995 buffer_put_int(&m, 1); 996 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 997 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 998 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 999 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 1000 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 1001 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 1002 } else 1003 buffer_put_int(&m, 0); 1004 1005 #ifndef OPENSSL_PRNG_ONLY 1006 rexec_send_rng_seed(&m); 1007 #endif 1008 1009 if (ssh_msg_send(fd, 0, &m) == -1) 1010 fatal("%s: ssh_msg_send failed", __func__); 1011 1012 buffer_free(&m); 1013 1014 debug3("%s: done", __func__); 1015 } 1016 1017 static void 1018 recv_rexec_state(int fd, Buffer *conf) 1019 { 1020 Buffer m; 1021 char *cp; 1022 u_int len; 1023 1024 debug3("%s: entering fd = %d", __func__, fd); 1025 1026 buffer_init(&m); 1027 1028 if (ssh_msg_recv(fd, &m) == -1) 1029 fatal("%s: ssh_msg_recv failed", __func__); 1030 if (buffer_get_char(&m) != 0) 1031 fatal("%s: rexec version mismatch", __func__); 1032 1033 cp = buffer_get_string(&m, &len); 1034 if (conf != NULL) 1035 buffer_append(conf, cp, len + 1); 1036 free(cp); 1037 1038 if (buffer_get_int(&m)) { 1039 if (sensitive_data.server_key != NULL) 1040 key_free(sensitive_data.server_key); 1041 sensitive_data.server_key = key_new_private(KEY_RSA1); 1042 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 1043 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 1044 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 1045 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 1046 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 1047 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 1048 rsa_generate_additional_parameters( 1049 sensitive_data.server_key->rsa); 1050 } 1051 1052 #ifndef OPENSSL_PRNG_ONLY 1053 rexec_recv_rng_seed(&m); 1054 #endif 1055 1056 buffer_free(&m); 1057 1058 debug3("%s: done", __func__); 1059 } 1060 1061 /* Accept a connection from inetd */ 1062 static void 1063 server_accept_inetd(int *sock_in, int *sock_out) 1064 { 1065 int fd; 1066 1067 startup_pipe = -1; 1068 if (rexeced_flag) { 1069 close(REEXEC_CONFIG_PASS_FD); 1070 *sock_in = *sock_out = dup(STDIN_FILENO); 1071 if (!debug_flag) { 1072 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1073 close(REEXEC_STARTUP_PIPE_FD); 1074 } 1075 } else { 1076 *sock_in = dup(STDIN_FILENO); 1077 *sock_out = dup(STDOUT_FILENO); 1078 } 1079 /* 1080 * We intentionally do not close the descriptors 0, 1, and 2 1081 * as our code for setting the descriptors won't work if 1082 * ttyfd happens to be one of those. 1083 */ 1084 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1085 dup2(fd, STDIN_FILENO); 1086 dup2(fd, STDOUT_FILENO); 1087 if (!log_stderr) 1088 dup2(fd, STDERR_FILENO); 1089 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1090 close(fd); 1091 } 1092 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1093 } 1094 1095 /* 1096 * Listen for TCP connections 1097 */ 1098 static void 1099 server_listen(void) 1100 { 1101 int ret, listen_sock, on = 1; 1102 struct addrinfo *ai; 1103 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1104 int socksize; 1105 socklen_t len; 1106 1107 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1108 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1109 continue; 1110 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1111 fatal("Too many listen sockets. " 1112 "Enlarge MAX_LISTEN_SOCKS"); 1113 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1114 ntop, sizeof(ntop), strport, sizeof(strport), 1115 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1116 error("getnameinfo failed: %.100s", 1117 ssh_gai_strerror(ret)); 1118 continue; 1119 } 1120 /* Create socket for listening. */ 1121 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1122 ai->ai_protocol); 1123 if (listen_sock < 0) { 1124 /* kernel may not support ipv6 */ 1125 verbose("socket: %.100s", strerror(errno)); 1126 continue; 1127 } 1128 if (set_nonblock(listen_sock) == -1) { 1129 close(listen_sock); 1130 continue; 1131 } 1132 /* 1133 * Set socket options. 1134 * Allow local port reuse in TIME_WAIT. 1135 */ 1136 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1137 &on, sizeof(on)) == -1) 1138 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1139 1140 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1141 if (ai->ai_family == AF_INET6) 1142 sock_set_v6only(listen_sock); 1143 1144 debug("Bind to port %s on %s.", strport, ntop); 1145 1146 len = sizeof(socksize); 1147 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, &socksize, &len); 1148 debug("Server TCP RWIN socket size: %d", socksize); 1149 debug("HPN Buffer Size: %d", options.hpn_buffer_size); 1150 1151 /* Bind the socket to the desired port. */ 1152 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1153 error("Bind to port %s on %s failed: %.200s.", 1154 strport, ntop, strerror(errno)); 1155 close(listen_sock); 1156 continue; 1157 } 1158 listen_socks[num_listen_socks] = listen_sock; 1159 num_listen_socks++; 1160 1161 /* Start listening on the port. */ 1162 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1163 fatal("listen on [%s]:%s: %.100s", 1164 ntop, strport, strerror(errno)); 1165 logit("Server listening on %s port %s.", ntop, strport); 1166 } 1167 freeaddrinfo(options.listen_addrs); 1168 1169 if (!num_listen_socks) 1170 fatal("Cannot bind any address."); 1171 } 1172 1173 /* 1174 * The main TCP accept loop. Note that, for the non-debug case, returns 1175 * from this function are in a forked subprocess. 1176 */ 1177 static void 1178 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1179 { 1180 fd_set *fdset; 1181 int i, j, ret, maxfd; 1182 int key_used = 0, startups = 0; 1183 int startup_p[2] = { -1 , -1 }; 1184 struct sockaddr_storage from; 1185 socklen_t fromlen; 1186 pid_t pid; 1187 u_char rnd[256]; 1188 1189 /* setup fd set for accept */ 1190 fdset = NULL; 1191 maxfd = 0; 1192 for (i = 0; i < num_listen_socks; i++) 1193 if (listen_socks[i] > maxfd) 1194 maxfd = listen_socks[i]; 1195 /* pipes connected to unauthenticated childs */ 1196 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1197 for (i = 0; i < options.max_startups; i++) 1198 startup_pipes[i] = -1; 1199 1200 /* 1201 * Stay listening for connections until the system crashes or 1202 * the daemon is killed with a signal. 1203 */ 1204 for (;;) { 1205 if (received_sighup) 1206 sighup_restart(); 1207 if (fdset != NULL) 1208 free(fdset); 1209 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1210 sizeof(fd_mask)); 1211 1212 for (i = 0; i < num_listen_socks; i++) 1213 FD_SET(listen_socks[i], fdset); 1214 for (i = 0; i < options.max_startups; i++) 1215 if (startup_pipes[i] != -1) 1216 FD_SET(startup_pipes[i], fdset); 1217 1218 /* Wait in select until there is a connection. */ 1219 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1220 if (ret < 0 && errno != EINTR) 1221 error("select: %.100s", strerror(errno)); 1222 if (received_sigterm) { 1223 logit("Received signal %d; terminating.", 1224 (int) received_sigterm); 1225 close_listen_socks(); 1226 unlink(options.pid_file); 1227 exit(received_sigterm == SIGTERM ? 0 : 255); 1228 } 1229 if (key_used && key_do_regen) { 1230 generate_ephemeral_server_key(); 1231 key_used = 0; 1232 key_do_regen = 0; 1233 } 1234 if (ret < 0) 1235 continue; 1236 1237 for (i = 0; i < options.max_startups; i++) 1238 if (startup_pipes[i] != -1 && 1239 FD_ISSET(startup_pipes[i], fdset)) { 1240 /* 1241 * the read end of the pipe is ready 1242 * if the child has closed the pipe 1243 * after successful authentication 1244 * or if the child has died 1245 */ 1246 close(startup_pipes[i]); 1247 startup_pipes[i] = -1; 1248 startups--; 1249 } 1250 for (i = 0; i < num_listen_socks; i++) { 1251 if (!FD_ISSET(listen_socks[i], fdset)) 1252 continue; 1253 fromlen = sizeof(from); 1254 *newsock = accept(listen_socks[i], 1255 (struct sockaddr *)&from, &fromlen); 1256 if (*newsock < 0) { 1257 if (errno != EINTR && errno != EWOULDBLOCK && 1258 errno != ECONNABORTED && errno != EAGAIN) 1259 error("accept: %.100s", 1260 strerror(errno)); 1261 if (errno == EMFILE || errno == ENFILE) 1262 usleep(100 * 1000); 1263 continue; 1264 } 1265 if (unset_nonblock(*newsock) == -1) { 1266 close(*newsock); 1267 continue; 1268 } 1269 if (drop_connection(startups) == 1) { 1270 debug("drop connection #%d", startups); 1271 close(*newsock); 1272 continue; 1273 } 1274 if (pipe(startup_p) == -1) { 1275 close(*newsock); 1276 continue; 1277 } 1278 1279 if (rexec_flag && socketpair(AF_UNIX, 1280 SOCK_STREAM, 0, config_s) == -1) { 1281 error("reexec socketpair: %s", 1282 strerror(errno)); 1283 close(*newsock); 1284 close(startup_p[0]); 1285 close(startup_p[1]); 1286 continue; 1287 } 1288 1289 for (j = 0; j < options.max_startups; j++) 1290 if (startup_pipes[j] == -1) { 1291 startup_pipes[j] = startup_p[0]; 1292 if (maxfd < startup_p[0]) 1293 maxfd = startup_p[0]; 1294 startups++; 1295 break; 1296 } 1297 1298 /* 1299 * Got connection. Fork a child to handle it, unless 1300 * we are in debugging mode. 1301 */ 1302 if (debug_flag) { 1303 /* 1304 * In debugging mode. Close the listening 1305 * socket, and start processing the 1306 * connection without forking. 1307 */ 1308 debug("Server will not fork when running in debugging mode."); 1309 close_listen_socks(); 1310 *sock_in = *newsock; 1311 *sock_out = *newsock; 1312 close(startup_p[0]); 1313 close(startup_p[1]); 1314 startup_pipe = -1; 1315 pid = getpid(); 1316 if (rexec_flag) { 1317 send_rexec_state(config_s[0], 1318 &cfg); 1319 close(config_s[0]); 1320 } 1321 break; 1322 } 1323 1324 /* 1325 * Normal production daemon. Fork, and have 1326 * the child process the connection. The 1327 * parent continues listening. 1328 */ 1329 platform_pre_fork(); 1330 if ((pid = fork()) == 0) { 1331 /* 1332 * Child. Close the listening and 1333 * max_startup sockets. Start using 1334 * the accepted socket. Reinitialize 1335 * logging (since our pid has changed). 1336 * We break out of the loop to handle 1337 * the connection. 1338 */ 1339 platform_post_fork_child(); 1340 startup_pipe = startup_p[1]; 1341 close_startup_pipes(); 1342 close_listen_socks(); 1343 *sock_in = *newsock; 1344 *sock_out = *newsock; 1345 log_init(__progname, 1346 options.log_level, 1347 options.log_facility, 1348 log_stderr); 1349 if (rexec_flag) 1350 close(config_s[0]); 1351 break; 1352 } 1353 1354 /* Parent. Stay in the loop. */ 1355 platform_post_fork_parent(pid); 1356 if (pid < 0) 1357 error("fork: %.100s", strerror(errno)); 1358 else 1359 debug("Forked child %ld.", (long)pid); 1360 1361 close(startup_p[1]); 1362 1363 if (rexec_flag) { 1364 send_rexec_state(config_s[0], &cfg); 1365 close(config_s[0]); 1366 close(config_s[1]); 1367 } 1368 1369 /* 1370 * Mark that the key has been used (it 1371 * was "given" to the child). 1372 */ 1373 if ((options.protocol & SSH_PROTO_1) && 1374 key_used == 0) { 1375 /* Schedule server key regeneration alarm. */ 1376 signal(SIGALRM, key_regeneration_alarm); 1377 alarm(options.key_regeneration_time); 1378 key_used = 1; 1379 } 1380 1381 close(*newsock); 1382 1383 /* 1384 * Ensure that our random state differs 1385 * from that of the child 1386 */ 1387 arc4random_stir(); 1388 arc4random_buf(rnd, sizeof(rnd)); 1389 RAND_seed(rnd, sizeof(rnd)); 1390 explicit_bzero(rnd, sizeof(rnd)); 1391 } 1392 1393 /* child process check (or debug mode) */ 1394 if (num_listen_socks < 0) 1395 break; 1396 } 1397 } 1398 1399 1400 /* 1401 * Main program for the daemon. 1402 */ 1403 int 1404 main(int ac, char **av) 1405 { 1406 extern char *optarg; 1407 extern int optind; 1408 int opt, i, j, on = 1; 1409 int sock_in = -1, sock_out = -1, newsock = -1; 1410 const char *remote_ip; 1411 int remote_port; 1412 char *line, *logfile = NULL; 1413 int config_s[2] = { -1 , -1 }; 1414 u_int n; 1415 u_int64_t ibytes, obytes; 1416 mode_t new_umask; 1417 Key *key; 1418 Key *pubkey; 1419 int keytype; 1420 Authctxt *authctxt; 1421 struct connection_info *connection_info = get_connection_info(0, 0); 1422 1423 #ifdef HAVE_SECUREWARE 1424 (void)set_auth_parameters(ac, av); 1425 #endif 1426 __progname = ssh_get_progname(av[0]); 1427 1428 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1429 saved_argc = ac; 1430 rexec_argc = ac; 1431 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1432 for (i = 0; i < ac; i++) 1433 saved_argv[i] = xstrdup(av[i]); 1434 saved_argv[i] = NULL; 1435 1436 #ifndef HAVE_SETPROCTITLE 1437 /* Prepare for later setproctitle emulation */ 1438 compat_init_setproctitle(ac, av); 1439 av = saved_argv; 1440 #endif 1441 1442 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1443 debug("setgroups(): %.200s", strerror(errno)); 1444 1445 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1446 sanitise_stdfd(); 1447 1448 /* Initialize configuration options to their default values. */ 1449 initialize_server_options(&options); 1450 1451 /* Parse command-line arguments. */ 1452 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeE:iqrtQRT46")) != -1) { 1453 switch (opt) { 1454 case '4': 1455 options.address_family = AF_INET; 1456 break; 1457 case '6': 1458 options.address_family = AF_INET6; 1459 break; 1460 case 'f': 1461 config_file_name = optarg; 1462 break; 1463 case 'c': 1464 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1465 fprintf(stderr, "too many host certificates.\n"); 1466 exit(1); 1467 } 1468 options.host_cert_files[options.num_host_cert_files++] = 1469 derelativise_path(optarg); 1470 break; 1471 case 'd': 1472 if (debug_flag == 0) { 1473 debug_flag = 1; 1474 options.log_level = SYSLOG_LEVEL_DEBUG1; 1475 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1476 options.log_level++; 1477 break; 1478 case 'D': 1479 no_daemon_flag = 1; 1480 break; 1481 case 'E': 1482 logfile = xstrdup(optarg); 1483 /* FALLTHROUGH */ 1484 case 'e': 1485 log_stderr = 1; 1486 break; 1487 case 'i': 1488 inetd_flag = 1; 1489 break; 1490 case 'r': 1491 rexec_flag = 0; 1492 break; 1493 case 'R': 1494 rexeced_flag = 1; 1495 inetd_flag = 1; 1496 break; 1497 case 'Q': 1498 /* ignored */ 1499 break; 1500 case 'q': 1501 options.log_level = SYSLOG_LEVEL_QUIET; 1502 break; 1503 case 'b': 1504 options.server_key_bits = (int)strtonum(optarg, 256, 1505 32768, NULL); 1506 break; 1507 case 'p': 1508 options.ports_from_cmdline = 1; 1509 if (options.num_ports >= MAX_PORTS) { 1510 fprintf(stderr, "too many ports.\n"); 1511 exit(1); 1512 } 1513 options.ports[options.num_ports++] = a2port(optarg); 1514 if (options.ports[options.num_ports-1] <= 0) { 1515 fprintf(stderr, "Bad port number.\n"); 1516 exit(1); 1517 } 1518 break; 1519 case 'g': 1520 if ((options.login_grace_time = convtime(optarg)) == -1) { 1521 fprintf(stderr, "Invalid login grace time.\n"); 1522 exit(1); 1523 } 1524 break; 1525 case 'k': 1526 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1527 fprintf(stderr, "Invalid key regeneration interval.\n"); 1528 exit(1); 1529 } 1530 break; 1531 case 'h': 1532 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1533 fprintf(stderr, "too many host keys.\n"); 1534 exit(1); 1535 } 1536 options.host_key_files[options.num_host_key_files++] = 1537 derelativise_path(optarg); 1538 break; 1539 case 't': 1540 test_flag = 1; 1541 break; 1542 case 'T': 1543 test_flag = 2; 1544 break; 1545 case 'C': 1546 if (parse_server_match_testspec(connection_info, 1547 optarg) == -1) 1548 exit(1); 1549 break; 1550 case 'u': 1551 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1552 if (utmp_len > MAXHOSTNAMELEN) { 1553 fprintf(stderr, "Invalid utmp length.\n"); 1554 exit(1); 1555 } 1556 break; 1557 case 'o': 1558 line = xstrdup(optarg); 1559 if (process_server_config_line(&options, line, 1560 "command-line", 0, NULL, NULL) != 0) 1561 exit(1); 1562 free(line); 1563 break; 1564 case '?': 1565 default: 1566 usage(); 1567 break; 1568 } 1569 } 1570 if (rexeced_flag || inetd_flag) 1571 rexec_flag = 0; 1572 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1573 fatal("sshd re-exec requires execution with an absolute path"); 1574 if (rexeced_flag) 1575 closefrom(REEXEC_MIN_FREE_FD); 1576 else 1577 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1578 1579 OpenSSL_add_all_algorithms(); 1580 1581 /* If requested, redirect the logs to the specified logfile. */ 1582 if (logfile != NULL) { 1583 log_redirect_stderr_to(logfile); 1584 free(logfile); 1585 } 1586 /* 1587 * Force logging to stderr until we have loaded the private host 1588 * key (unless started from inetd) 1589 */ 1590 log_init(__progname, 1591 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1592 SYSLOG_LEVEL_INFO : options.log_level, 1593 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1594 SYSLOG_FACILITY_AUTH : options.log_facility, 1595 log_stderr || !inetd_flag); 1596 1597 /* 1598 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1599 * root's environment 1600 */ 1601 if (getenv("KRB5CCNAME") != NULL) 1602 (void) unsetenv("KRB5CCNAME"); 1603 1604 #ifdef _UNICOS 1605 /* Cray can define user privs drop all privs now! 1606 * Not needed on PRIV_SU systems! 1607 */ 1608 drop_cray_privs(); 1609 #endif 1610 1611 sensitive_data.server_key = NULL; 1612 sensitive_data.ssh1_host_key = NULL; 1613 sensitive_data.have_ssh1_key = 0; 1614 sensitive_data.have_ssh2_key = 0; 1615 1616 /* 1617 * If we're doing an extended config test, make sure we have all of 1618 * the parameters we need. If we're not doing an extended test, 1619 * do not silently ignore connection test params. 1620 */ 1621 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0) 1622 fatal("user, host and addr are all required when testing " 1623 "Match configs"); 1624 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0) 1625 fatal("Config test connection parameter (-C) provided without " 1626 "test mode (-T)"); 1627 1628 /* Fetch our configuration */ 1629 buffer_init(&cfg); 1630 if (rexeced_flag) 1631 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1632 else 1633 load_server_config(config_file_name, &cfg); 1634 1635 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1636 &cfg, NULL); 1637 1638 seed_rng(); 1639 1640 /* Fill in default values for those options not explicitly set. */ 1641 fill_default_server_options(&options); 1642 1643 /* challenge-response is implemented via keyboard interactive */ 1644 if (options.challenge_response_authentication) 1645 options.kbd_interactive_authentication = 1; 1646 1647 /* Check that options are sensible */ 1648 if (options.authorized_keys_command_user == NULL && 1649 (options.authorized_keys_command != NULL && 1650 strcasecmp(options.authorized_keys_command, "none") != 0)) 1651 fatal("AuthorizedKeysCommand set without " 1652 "AuthorizedKeysCommandUser"); 1653 1654 /* 1655 * Check whether there is any path through configured auth methods. 1656 * Unfortunately it is not possible to verify this generally before 1657 * daemonisation in the presence of Match block, but this catches 1658 * and warns for trivial misconfigurations that could break login. 1659 */ 1660 if (options.num_auth_methods != 0) { 1661 if ((options.protocol & SSH_PROTO_1)) 1662 fatal("AuthenticationMethods is not supported with " 1663 "SSH protocol 1"); 1664 for (n = 0; n < options.num_auth_methods; n++) { 1665 if (auth2_methods_valid(options.auth_methods[n], 1666 1) == 0) 1667 break; 1668 } 1669 if (n >= options.num_auth_methods) 1670 fatal("AuthenticationMethods cannot be satisfied by " 1671 "enabled authentication methods"); 1672 } 1673 1674 /* set default channel AF */ 1675 channel_set_af(options.address_family); 1676 1677 /* Check that there are no remaining arguments. */ 1678 if (optind < ac) { 1679 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1680 exit(1); 1681 } 1682 1683 debug("sshd version %.100s%.100s%s%.100s, %.100s", 1684 SSH_RELEASE, 1685 options.hpn_disabled ? "" : SSH_VERSION_HPN, 1686 *options.version_addendum == '\0' ? "" : " ", 1687 options.version_addendum, 1688 SSLeay_version(SSLEAY_VERSION)); 1689 1690 /* Store privilege separation user for later use if required. */ 1691 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1692 if (use_privsep || options.kerberos_authentication) 1693 fatal("Privilege separation user %s does not exist", 1694 SSH_PRIVSEP_USER); 1695 } else { 1696 explicit_bzero(privsep_pw->pw_passwd, 1697 strlen(privsep_pw->pw_passwd)); 1698 privsep_pw = pwcopy(privsep_pw); 1699 free(privsep_pw->pw_passwd); 1700 privsep_pw->pw_passwd = xstrdup("*"); 1701 } 1702 endpwent(); 1703 1704 /* load host keys */ 1705 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1706 sizeof(Key *)); 1707 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1708 sizeof(Key *)); 1709 for (i = 0; i < options.num_host_key_files; i++) { 1710 sensitive_data.host_keys[i] = NULL; 1711 sensitive_data.host_pubkeys[i] = NULL; 1712 } 1713 1714 if (options.host_key_agent) { 1715 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1716 setenv(SSH_AUTHSOCKET_ENV_NAME, 1717 options.host_key_agent, 1); 1718 have_agent = ssh_agent_present(); 1719 } 1720 1721 for (i = 0; i < options.num_host_key_files; i++) { 1722 key = key_load_private(options.host_key_files[i], "", NULL); 1723 pubkey = key_load_public(options.host_key_files[i], NULL); 1724 sensitive_data.host_keys[i] = key; 1725 sensitive_data.host_pubkeys[i] = pubkey; 1726 1727 if (key == NULL && pubkey != NULL && pubkey->type != KEY_RSA1 && 1728 have_agent) { 1729 debug("will rely on agent for hostkey %s", 1730 options.host_key_files[i]); 1731 keytype = pubkey->type; 1732 } else if (key != NULL) { 1733 keytype = key->type; 1734 } else { 1735 error("Could not load host key: %s", 1736 options.host_key_files[i]); 1737 sensitive_data.host_keys[i] = NULL; 1738 sensitive_data.host_pubkeys[i] = NULL; 1739 continue; 1740 } 1741 1742 switch (keytype) { 1743 case KEY_RSA1: 1744 sensitive_data.ssh1_host_key = key; 1745 sensitive_data.have_ssh1_key = 1; 1746 break; 1747 case KEY_RSA: 1748 case KEY_DSA: 1749 case KEY_ECDSA: 1750 case KEY_ED25519: 1751 sensitive_data.have_ssh2_key = 1; 1752 break; 1753 } 1754 debug("private host key: #%d type %d %s", i, keytype, 1755 key_type(key ? key : pubkey)); 1756 } 1757 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1758 logit("Disabling protocol version 1. Could not load host key"); 1759 options.protocol &= ~SSH_PROTO_1; 1760 } 1761 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1762 logit("Disabling protocol version 2. Could not load host key"); 1763 options.protocol &= ~SSH_PROTO_2; 1764 } 1765 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1766 logit("sshd: no hostkeys available -- exiting."); 1767 exit(1); 1768 } 1769 1770 /* 1771 * Load certificates. They are stored in an array at identical 1772 * indices to the public keys that they relate to. 1773 */ 1774 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1775 sizeof(Key *)); 1776 for (i = 0; i < options.num_host_key_files; i++) 1777 sensitive_data.host_certificates[i] = NULL; 1778 1779 for (i = 0; i < options.num_host_cert_files; i++) { 1780 key = key_load_public(options.host_cert_files[i], NULL); 1781 if (key == NULL) { 1782 error("Could not load host certificate: %s", 1783 options.host_cert_files[i]); 1784 continue; 1785 } 1786 if (!key_is_cert(key)) { 1787 error("Certificate file is not a certificate: %s", 1788 options.host_cert_files[i]); 1789 key_free(key); 1790 continue; 1791 } 1792 /* Find matching private key */ 1793 for (j = 0; j < options.num_host_key_files; j++) { 1794 if (key_equal_public(key, 1795 sensitive_data.host_keys[j])) { 1796 sensitive_data.host_certificates[j] = key; 1797 break; 1798 } 1799 } 1800 if (j >= options.num_host_key_files) { 1801 error("No matching private key for certificate: %s", 1802 options.host_cert_files[i]); 1803 key_free(key); 1804 continue; 1805 } 1806 sensitive_data.host_certificates[j] = key; 1807 debug("host certificate: #%d type %d %s", j, key->type, 1808 key_type(key)); 1809 } 1810 /* Check certain values for sanity. */ 1811 if (options.protocol & SSH_PROTO_1) { 1812 if (options.server_key_bits < 512 || 1813 options.server_key_bits > 32768) { 1814 fprintf(stderr, "Bad server key size.\n"); 1815 exit(1); 1816 } 1817 /* 1818 * Check that server and host key lengths differ sufficiently. This 1819 * is necessary to make double encryption work with rsaref. Oh, I 1820 * hate software patents. I dont know if this can go? Niels 1821 */ 1822 if (options.server_key_bits > 1823 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1824 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1825 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1826 SSH_KEY_BITS_RESERVED) { 1827 options.server_key_bits = 1828 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1829 SSH_KEY_BITS_RESERVED; 1830 debug("Forcing server key to %d bits to make it differ from host key.", 1831 options.server_key_bits); 1832 } 1833 } 1834 1835 if (use_privsep) { 1836 struct stat st; 1837 1838 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1839 (S_ISDIR(st.st_mode) == 0)) 1840 fatal("Missing privilege separation directory: %s", 1841 _PATH_PRIVSEP_CHROOT_DIR); 1842 1843 #ifdef HAVE_CYGWIN 1844 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1845 (st.st_uid != getuid () || 1846 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1847 #else 1848 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1849 #endif 1850 fatal("%s must be owned by root and not group or " 1851 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1852 } 1853 1854 if (test_flag > 1) { 1855 if (server_match_spec_complete(connection_info) == 1) 1856 parse_server_match_config(&options, connection_info); 1857 dump_config(&options); 1858 } 1859 1860 /* Configuration looks good, so exit if in test mode. */ 1861 if (test_flag) 1862 exit(0); 1863 1864 /* 1865 * Clear out any supplemental groups we may have inherited. This 1866 * prevents inadvertent creation of files with bad modes (in the 1867 * portable version at least, it's certainly possible for PAM 1868 * to create a file, and we can't control the code in every 1869 * module which might be used). 1870 */ 1871 if (setgroups(0, NULL) < 0) 1872 debug("setgroups() failed: %.200s", strerror(errno)); 1873 1874 if (rexec_flag) { 1875 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1876 for (i = 0; i < rexec_argc; i++) { 1877 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1878 rexec_argv[i] = saved_argv[i]; 1879 } 1880 rexec_argv[rexec_argc] = "-R"; 1881 rexec_argv[rexec_argc + 1] = NULL; 1882 } 1883 1884 /* Ensure that umask disallows at least group and world write */ 1885 new_umask = umask(0077) | 0022; 1886 (void) umask(new_umask); 1887 1888 /* Initialize the log (it is reinitialized below in case we forked). */ 1889 if (debug_flag && (!inetd_flag || rexeced_flag)) 1890 log_stderr = 1; 1891 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1892 1893 /* 1894 * If not in debugging mode, and not started from inetd, disconnect 1895 * from the controlling terminal, and fork. The original process 1896 * exits. 1897 */ 1898 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1899 #ifdef TIOCNOTTY 1900 int fd; 1901 #endif /* TIOCNOTTY */ 1902 if (daemon(0, 0) < 0) 1903 fatal("daemon() failed: %.200s", strerror(errno)); 1904 1905 /* Disconnect from the controlling tty. */ 1906 #ifdef TIOCNOTTY 1907 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1908 if (fd >= 0) { 1909 (void) ioctl(fd, TIOCNOTTY, NULL); 1910 close(fd); 1911 } 1912 #endif /* TIOCNOTTY */ 1913 } 1914 /* Reinitialize the log (because of the fork above). */ 1915 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1916 1917 /* Avoid killing the process in high-pressure swapping environments. */ 1918 if (!inetd_flag && madvise(NULL, 0, MADV_PROTECT) != 0) 1919 debug("madvise(): %.200s", strerror(errno)); 1920 1921 /* Chdir to the root directory so that the current disk can be 1922 unmounted if desired. */ 1923 if (chdir("/") == -1) 1924 error("chdir(\"/\"): %s", strerror(errno)); 1925 1926 /* ignore SIGPIPE */ 1927 signal(SIGPIPE, SIG_IGN); 1928 1929 /* Get a connection, either from inetd or a listening TCP socket */ 1930 if (inetd_flag) { 1931 server_accept_inetd(&sock_in, &sock_out); 1932 } else { 1933 platform_pre_listen(); 1934 server_listen(); 1935 1936 if (options.protocol & SSH_PROTO_1) 1937 generate_ephemeral_server_key(); 1938 1939 signal(SIGHUP, sighup_handler); 1940 signal(SIGCHLD, main_sigchld_handler); 1941 signal(SIGTERM, sigterm_handler); 1942 signal(SIGQUIT, sigterm_handler); 1943 1944 /* 1945 * Write out the pid file after the sigterm handler 1946 * is setup and the listen sockets are bound 1947 */ 1948 if (!debug_flag) { 1949 FILE *f = fopen(options.pid_file, "w"); 1950 1951 if (f == NULL) { 1952 error("Couldn't create pid file \"%s\": %s", 1953 options.pid_file, strerror(errno)); 1954 } else { 1955 fprintf(f, "%ld\n", (long) getpid()); 1956 fclose(f); 1957 } 1958 } 1959 1960 /* Accept a connection and return in a forked child */ 1961 server_accept_loop(&sock_in, &sock_out, 1962 &newsock, config_s); 1963 } 1964 1965 /* This is the child processing a new connection. */ 1966 setproctitle("%s", "[accepted]"); 1967 1968 /* 1969 * Create a new session and process group since the 4.4BSD 1970 * setlogin() affects the entire process group. We don't 1971 * want the child to be able to affect the parent. 1972 */ 1973 #if !defined(SSHD_ACQUIRES_CTTY) 1974 /* 1975 * If setsid is called, on some platforms sshd will later acquire a 1976 * controlling terminal which will result in "could not set 1977 * controlling tty" errors. 1978 */ 1979 if (!debug_flag && !inetd_flag && setsid() < 0) 1980 error("setsid: %.100s", strerror(errno)); 1981 #endif 1982 1983 if (rexec_flag) { 1984 int fd; 1985 1986 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1987 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1988 dup2(newsock, STDIN_FILENO); 1989 dup2(STDIN_FILENO, STDOUT_FILENO); 1990 if (startup_pipe == -1) 1991 close(REEXEC_STARTUP_PIPE_FD); 1992 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1993 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1994 close(startup_pipe); 1995 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1996 } 1997 1998 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1999 close(config_s[1]); 2000 2001 execv(rexec_argv[0], rexec_argv); 2002 2003 /* Reexec has failed, fall back and continue */ 2004 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 2005 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 2006 log_init(__progname, options.log_level, 2007 options.log_facility, log_stderr); 2008 2009 /* Clean up fds */ 2010 close(REEXEC_CONFIG_PASS_FD); 2011 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2012 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 2013 dup2(fd, STDIN_FILENO); 2014 dup2(fd, STDOUT_FILENO); 2015 if (fd > STDERR_FILENO) 2016 close(fd); 2017 } 2018 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2019 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2020 } 2021 2022 /* Executed child processes don't need these. */ 2023 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2024 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2025 2026 /* 2027 * Disable the key regeneration alarm. We will not regenerate the 2028 * key since we are no longer in a position to give it to anyone. We 2029 * will not restart on SIGHUP since it no longer makes sense. 2030 */ 2031 alarm(0); 2032 signal(SIGALRM, SIG_DFL); 2033 signal(SIGHUP, SIG_DFL); 2034 signal(SIGTERM, SIG_DFL); 2035 signal(SIGQUIT, SIG_DFL); 2036 signal(SIGCHLD, SIG_DFL); 2037 signal(SIGINT, SIG_DFL); 2038 2039 #ifdef __FreeBSD__ 2040 /* 2041 * Initialize the resolver. This may not happen automatically 2042 * before privsep chroot(). 2043 */ 2044 if ((_res.options & RES_INIT) == 0) { 2045 debug("res_init()"); 2046 res_init(); 2047 } 2048 #ifdef GSSAPI 2049 /* 2050 * Force GSS-API to parse its configuration and load any 2051 * mechanism plugins. 2052 */ 2053 { 2054 gss_OID_set mechs; 2055 OM_uint32 minor_status; 2056 gss_indicate_mechs(&minor_status, &mechs); 2057 gss_release_oid_set(&minor_status, &mechs); 2058 } 2059 #endif 2060 #endif 2061 2062 /* 2063 * Register our connection. This turns encryption off because we do 2064 * not have a key. 2065 */ 2066 packet_set_connection(sock_in, sock_out); 2067 packet_set_server(); 2068 2069 /* Set SO_KEEPALIVE if requested. */ 2070 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 2071 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 2072 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2073 2074 if ((remote_port = get_remote_port()) < 0) { 2075 debug("get_remote_port failed"); 2076 cleanup_exit(255); 2077 } 2078 2079 /* 2080 * We use get_canonical_hostname with usedns = 0 instead of 2081 * get_remote_ipaddr here so IP options will be checked. 2082 */ 2083 (void) get_canonical_hostname(0); 2084 /* 2085 * The rest of the code depends on the fact that 2086 * get_remote_ipaddr() caches the remote ip, even if 2087 * the socket goes away. 2088 */ 2089 remote_ip = get_remote_ipaddr(); 2090 2091 #ifdef SSH_AUDIT_EVENTS 2092 audit_connection_from(remote_ip, remote_port); 2093 #endif 2094 #ifdef LIBWRAP 2095 allow_severity = options.log_facility|LOG_INFO; 2096 deny_severity = options.log_facility|LOG_WARNING; 2097 /* Check whether logins are denied from this host. */ 2098 if (packet_connection_is_on_socket()) { 2099 struct request_info req; 2100 2101 request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); 2102 fromhost(&req); 2103 2104 if (!hosts_access(&req)) { 2105 debug("Connection refused by tcp wrapper"); 2106 refuse(&req); 2107 /* NOTREACHED */ 2108 fatal("libwrap refuse returns"); 2109 } 2110 } 2111 #endif /* LIBWRAP */ 2112 2113 /* Log the connection. */ 2114 verbose("Connection from %s port %d on %s port %d", 2115 remote_ip, remote_port, 2116 get_local_ipaddr(sock_in), get_local_port()); 2117 2118 /* Set HPN options for the child. */ 2119 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size); 2120 2121 /* 2122 * We don't want to listen forever unless the other side 2123 * successfully authenticates itself. So we set up an alarm which is 2124 * cleared after successful authentication. A limit of zero 2125 * indicates no limit. Note that we don't set the alarm in debugging 2126 * mode; it is just annoying to have the server exit just when you 2127 * are about to discover the bug. 2128 */ 2129 signal(SIGALRM, grace_alarm_handler); 2130 if (!debug_flag) 2131 alarm(options.login_grace_time); 2132 2133 sshd_exchange_identification(sock_in, sock_out); 2134 2135 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 2136 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 2137 generate_ephemeral_server_key(); 2138 2139 packet_set_nonblocking(); 2140 2141 /* allocate authentication context */ 2142 authctxt = xcalloc(1, sizeof(*authctxt)); 2143 2144 authctxt->loginmsg = &loginmsg; 2145 2146 /* XXX global for cleanup, access from other modules */ 2147 the_authctxt = authctxt; 2148 2149 /* prepare buffer to collect messages to display to user after login */ 2150 buffer_init(&loginmsg); 2151 auth_debug_reset(); 2152 2153 if (use_privsep) { 2154 if (privsep_preauth(authctxt) == 1) 2155 goto authenticated; 2156 } else if (compat20 && have_agent) 2157 auth_conn = ssh_get_authentication_connection(); 2158 2159 /* perform the key exchange */ 2160 /* authenticate user and start session */ 2161 if (compat20) { 2162 do_ssh2_kex(); 2163 do_authentication2(authctxt); 2164 } else { 2165 do_ssh1_kex(); 2166 do_authentication(authctxt); 2167 } 2168 /* 2169 * If we use privilege separation, the unprivileged child transfers 2170 * the current keystate and exits 2171 */ 2172 if (use_privsep) { 2173 mm_send_keystate(pmonitor); 2174 exit(0); 2175 } 2176 2177 authenticated: 2178 /* 2179 * Cancel the alarm we set to limit the time taken for 2180 * authentication. 2181 */ 2182 alarm(0); 2183 signal(SIGALRM, SIG_DFL); 2184 authctxt->authenticated = 1; 2185 if (startup_pipe != -1) { 2186 close(startup_pipe); 2187 startup_pipe = -1; 2188 } 2189 2190 #ifdef SSH_AUDIT_EVENTS 2191 audit_event(SSH_AUTH_SUCCESS); 2192 #endif 2193 2194 #ifdef GSSAPI 2195 if (options.gss_authentication) { 2196 temporarily_use_uid(authctxt->pw); 2197 ssh_gssapi_storecreds(); 2198 restore_uid(); 2199 } 2200 #endif 2201 #ifdef USE_PAM 2202 if (options.use_pam) { 2203 do_pam_setcred(1); 2204 do_pam_session(); 2205 } 2206 #endif 2207 2208 /* 2209 * In privilege separation, we fork another child and prepare 2210 * file descriptor passing. 2211 */ 2212 if (use_privsep) { 2213 privsep_postauth(authctxt); 2214 /* the monitor process [priv] will not return */ 2215 if (!compat20) 2216 destroy_sensitive_data(); 2217 } 2218 2219 packet_set_timeout(options.client_alive_interval, 2220 options.client_alive_count_max); 2221 2222 /* Start session. */ 2223 do_authenticated(authctxt); 2224 2225 /* The connection has been terminated. */ 2226 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 2227 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 2228 verbose("Transferred: sent %llu, received %llu bytes", 2229 (unsigned long long)obytes, (unsigned long long)ibytes); 2230 2231 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2232 2233 #ifdef USE_PAM 2234 if (options.use_pam) 2235 finish_pam(); 2236 #endif /* USE_PAM */ 2237 2238 #ifdef SSH_AUDIT_EVENTS 2239 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2240 #endif 2241 2242 packet_close(); 2243 2244 if (use_privsep) 2245 mm_terminate(); 2246 2247 exit(0); 2248 } 2249 2250 /* 2251 * Decrypt session_key_int using our private server key and private host key 2252 * (key with larger modulus first). 2253 */ 2254 int 2255 ssh1_session_key(BIGNUM *session_key_int) 2256 { 2257 int rsafail = 0; 2258 2259 if (BN_cmp(sensitive_data.server_key->rsa->n, 2260 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2261 /* Server key has bigger modulus. */ 2262 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2263 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2264 SSH_KEY_BITS_RESERVED) { 2265 fatal("do_connection: %s: " 2266 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2267 get_remote_ipaddr(), 2268 BN_num_bits(sensitive_data.server_key->rsa->n), 2269 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2270 SSH_KEY_BITS_RESERVED); 2271 } 2272 if (rsa_private_decrypt(session_key_int, session_key_int, 2273 sensitive_data.server_key->rsa) <= 0) 2274 rsafail++; 2275 if (rsa_private_decrypt(session_key_int, session_key_int, 2276 sensitive_data.ssh1_host_key->rsa) <= 0) 2277 rsafail++; 2278 } else { 2279 /* Host key has bigger modulus (or they are equal). */ 2280 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2281 BN_num_bits(sensitive_data.server_key->rsa->n) + 2282 SSH_KEY_BITS_RESERVED) { 2283 fatal("do_connection: %s: " 2284 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2285 get_remote_ipaddr(), 2286 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2287 BN_num_bits(sensitive_data.server_key->rsa->n), 2288 SSH_KEY_BITS_RESERVED); 2289 } 2290 if (rsa_private_decrypt(session_key_int, session_key_int, 2291 sensitive_data.ssh1_host_key->rsa) < 0) 2292 rsafail++; 2293 if (rsa_private_decrypt(session_key_int, session_key_int, 2294 sensitive_data.server_key->rsa) < 0) 2295 rsafail++; 2296 } 2297 return (rsafail); 2298 } 2299 /* 2300 * SSH1 key exchange 2301 */ 2302 static void 2303 do_ssh1_kex(void) 2304 { 2305 int i, len; 2306 int rsafail = 0; 2307 BIGNUM *session_key_int; 2308 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2309 u_char cookie[8]; 2310 u_int cipher_type, auth_mask, protocol_flags; 2311 2312 /* 2313 * Generate check bytes that the client must send back in the user 2314 * packet in order for it to be accepted; this is used to defy ip 2315 * spoofing attacks. Note that this only works against somebody 2316 * doing IP spoofing from a remote machine; any machine on the local 2317 * network can still see outgoing packets and catch the random 2318 * cookie. This only affects rhosts authentication, and this is one 2319 * of the reasons why it is inherently insecure. 2320 */ 2321 arc4random_buf(cookie, sizeof(cookie)); 2322 2323 /* 2324 * Send our public key. We include in the packet 64 bits of random 2325 * data that must be matched in the reply in order to prevent IP 2326 * spoofing. 2327 */ 2328 packet_start(SSH_SMSG_PUBLIC_KEY); 2329 for (i = 0; i < 8; i++) 2330 packet_put_char(cookie[i]); 2331 2332 /* Store our public server RSA key. */ 2333 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2334 packet_put_bignum(sensitive_data.server_key->rsa->e); 2335 packet_put_bignum(sensitive_data.server_key->rsa->n); 2336 2337 /* Store our public host RSA key. */ 2338 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2339 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2340 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2341 2342 /* Put protocol flags. */ 2343 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2344 2345 /* Declare which ciphers we support. */ 2346 packet_put_int(cipher_mask_ssh1(0)); 2347 2348 /* Declare supported authentication types. */ 2349 auth_mask = 0; 2350 if (options.rhosts_rsa_authentication) 2351 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2352 if (options.rsa_authentication) 2353 auth_mask |= 1 << SSH_AUTH_RSA; 2354 if (options.challenge_response_authentication == 1) 2355 auth_mask |= 1 << SSH_AUTH_TIS; 2356 if (options.password_authentication) 2357 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2358 packet_put_int(auth_mask); 2359 2360 /* Send the packet and wait for it to be sent. */ 2361 packet_send(); 2362 packet_write_wait(); 2363 2364 debug("Sent %d bit server key and %d bit host key.", 2365 BN_num_bits(sensitive_data.server_key->rsa->n), 2366 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2367 2368 /* Read clients reply (cipher type and session key). */ 2369 packet_read_expect(SSH_CMSG_SESSION_KEY); 2370 2371 /* Get cipher type and check whether we accept this. */ 2372 cipher_type = packet_get_char(); 2373 2374 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2375 packet_disconnect("Warning: client selects unsupported cipher."); 2376 2377 /* Get check bytes from the packet. These must match those we 2378 sent earlier with the public key packet. */ 2379 for (i = 0; i < 8; i++) 2380 if (cookie[i] != packet_get_char()) 2381 packet_disconnect("IP Spoofing check bytes do not match."); 2382 2383 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2384 2385 /* Get the encrypted integer. */ 2386 if ((session_key_int = BN_new()) == NULL) 2387 fatal("do_ssh1_kex: BN_new failed"); 2388 packet_get_bignum(session_key_int); 2389 2390 protocol_flags = packet_get_int(); 2391 packet_set_protocol_flags(protocol_flags); 2392 packet_check_eom(); 2393 2394 /* Decrypt session_key_int using host/server keys */ 2395 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2396 2397 /* 2398 * Extract session key from the decrypted integer. The key is in the 2399 * least significant 256 bits of the integer; the first byte of the 2400 * key is in the highest bits. 2401 */ 2402 if (!rsafail) { 2403 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2404 len = BN_num_bytes(session_key_int); 2405 if (len < 0 || (u_int)len > sizeof(session_key)) { 2406 error("do_ssh1_kex: bad session key len from %s: " 2407 "session_key_int %d > sizeof(session_key) %lu", 2408 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2409 rsafail++; 2410 } else { 2411 explicit_bzero(session_key, sizeof(session_key)); 2412 BN_bn2bin(session_key_int, 2413 session_key + sizeof(session_key) - len); 2414 2415 derive_ssh1_session_id( 2416 sensitive_data.ssh1_host_key->rsa->n, 2417 sensitive_data.server_key->rsa->n, 2418 cookie, session_id); 2419 /* 2420 * Xor the first 16 bytes of the session key with the 2421 * session id. 2422 */ 2423 for (i = 0; i < 16; i++) 2424 session_key[i] ^= session_id[i]; 2425 } 2426 } 2427 if (rsafail) { 2428 int bytes = BN_num_bytes(session_key_int); 2429 u_char *buf = xmalloc(bytes); 2430 struct ssh_digest_ctx *md; 2431 2432 logit("do_connection: generating a fake encryption key"); 2433 BN_bn2bin(session_key_int, buf); 2434 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || 2435 ssh_digest_update(md, buf, bytes) < 0 || 2436 ssh_digest_update(md, sensitive_data.ssh1_cookie, 2437 SSH_SESSION_KEY_LENGTH) < 0 || 2438 ssh_digest_final(md, session_key, sizeof(session_key)) < 0) 2439 fatal("%s: md5 failed", __func__); 2440 ssh_digest_free(md); 2441 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || 2442 ssh_digest_update(md, session_key, 16) < 0 || 2443 ssh_digest_update(md, sensitive_data.ssh1_cookie, 2444 SSH_SESSION_KEY_LENGTH) < 0 || 2445 ssh_digest_final(md, session_key + 16, 2446 sizeof(session_key) - 16) < 0) 2447 fatal("%s: md5 failed", __func__); 2448 ssh_digest_free(md); 2449 explicit_bzero(buf, bytes); 2450 free(buf); 2451 for (i = 0; i < 16; i++) 2452 session_id[i] = session_key[i] ^ session_key[i + 16]; 2453 } 2454 /* Destroy the private and public keys. No longer. */ 2455 destroy_sensitive_data(); 2456 2457 if (use_privsep) 2458 mm_ssh1_session_id(session_id); 2459 2460 /* Destroy the decrypted integer. It is no longer needed. */ 2461 BN_clear_free(session_key_int); 2462 2463 /* Set the session key. From this on all communications will be encrypted. */ 2464 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2465 2466 /* Destroy our copy of the session key. It is no longer needed. */ 2467 explicit_bzero(session_key, sizeof(session_key)); 2468 2469 debug("Received session key; encryption turned on."); 2470 2471 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2472 packet_start(SSH_SMSG_SUCCESS); 2473 packet_send(); 2474 packet_write_wait(); 2475 } 2476 2477 void 2478 sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, u_int *slen, 2479 u_char *data, u_int dlen) 2480 { 2481 if (privkey) { 2482 if (PRIVSEP(key_sign(privkey, signature, slen, data, dlen) < 0)) 2483 fatal("%s: key_sign failed", __func__); 2484 } else if (use_privsep) { 2485 if (mm_key_sign(pubkey, signature, slen, data, dlen) < 0) 2486 fatal("%s: pubkey_sign failed", __func__); 2487 } else { 2488 if (ssh_agent_sign(auth_conn, pubkey, signature, slen, data, 2489 dlen)) 2490 fatal("%s: ssh_agent_sign failed", __func__); 2491 } 2492 } 2493 2494 /* 2495 * SSH2 key exchange: diffie-hellman-group1-sha1 2496 */ 2497 static void 2498 do_ssh2_kex(void) 2499 { 2500 Kex *kex; 2501 2502 if (options.ciphers != NULL) { 2503 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2504 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2505 #ifdef NONE_CIPHER_ENABLED 2506 } else if (options.none_enabled == 1) { 2507 debug ("WARNING: None cipher enabled"); 2508 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2509 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE; 2510 #endif 2511 } 2512 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2513 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2514 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2515 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2516 2517 if (options.macs != NULL) { 2518 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2519 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2520 } 2521 if (options.compression == COMP_NONE) { 2522 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2523 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2524 } else if (options.compression == COMP_DELAYED) { 2525 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2526 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2527 } 2528 if (options.kex_algorithms != NULL) 2529 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 2530 2531 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2532 myproposal[PROPOSAL_KEX_ALGS]); 2533 2534 if (options.rekey_limit || options.rekey_interval) 2535 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 2536 (time_t)options.rekey_interval); 2537 2538 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2539 list_hostkey_types()); 2540 2541 /* start key exchange */ 2542 kex = kex_setup(myproposal); 2543 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2544 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2545 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2546 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2547 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2548 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2549 kex->server = 1; 2550 kex->client_version_string=client_version_string; 2551 kex->server_version_string=server_version_string; 2552 kex->load_host_public_key=&get_hostkey_public_by_type; 2553 kex->load_host_private_key=&get_hostkey_private_by_type; 2554 kex->host_key_index=&get_hostkey_index; 2555 kex->sign = sshd_hostkey_sign; 2556 2557 xxx_kex = kex; 2558 2559 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2560 2561 session_id2 = kex->session_id; 2562 session_id2_len = kex->session_id_len; 2563 2564 #ifdef DEBUG_KEXDH 2565 /* send 1st encrypted/maced/compressed message */ 2566 packet_start(SSH2_MSG_IGNORE); 2567 packet_put_cstring("markus"); 2568 packet_send(); 2569 packet_write_wait(); 2570 #endif 2571 debug("KEX done"); 2572 } 2573 2574 /* server specific fatal cleanup */ 2575 void 2576 cleanup_exit(int i) 2577 { 2578 if (the_authctxt) { 2579 do_cleanup(the_authctxt); 2580 if (use_privsep && privsep_is_preauth && pmonitor->m_pid > 1) { 2581 debug("Killing privsep child %d", pmonitor->m_pid); 2582 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2583 errno != ESRCH) 2584 error("%s: kill(%d): %s", __func__, 2585 pmonitor->m_pid, strerror(errno)); 2586 } 2587 } 2588 #ifdef SSH_AUDIT_EVENTS 2589 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2590 if (!use_privsep || mm_is_monitor()) 2591 audit_event(SSH_CONNECTION_ABANDON); 2592 #endif 2593 _exit(i); 2594 } 2595