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 47 #include <sys/types.h> 48 #include <sys/ioctl.h> 49 #include <sys/socket.h> 50 #ifdef HAVE_SYS_STAT_H 51 # include <sys/stat.h> 52 #endif 53 #ifdef HAVE_SYS_TIME_H 54 # include <sys/time.h> 55 #endif 56 #include "openbsd-compat/sys-tree.h" 57 #include "openbsd-compat/sys-queue.h" 58 #include <sys/wait.h> 59 60 #include <errno.h> 61 #include <fcntl.h> 62 #include <netdb.h> 63 #ifdef HAVE_PATHS_H 64 #include <paths.h> 65 #endif 66 #include <grp.h> 67 #include <pwd.h> 68 #include <signal.h> 69 #include <stdarg.h> 70 #include <stdio.h> 71 #include <stdlib.h> 72 #include <string.h> 73 #include <unistd.h> 74 75 #ifdef WITH_OPENSSL 76 #include <openssl/dh.h> 77 #include <openssl/bn.h> 78 #include <openssl/rand.h> 79 #include "openbsd-compat/openssl-compat.h" 80 #endif 81 82 #ifdef HAVE_SECUREWARE 83 #include <sys/security.h> 84 #include <prot.h> 85 #endif 86 87 #include <resolv.h> 88 #include "xmalloc.h" 89 #include "ssh.h" 90 #include "ssh1.h" 91 #include "ssh2.h" 92 #include "rsa.h" 93 #include "sshpty.h" 94 #include "packet.h" 95 #include "log.h" 96 #include "buffer.h" 97 #include "misc.h" 98 #include "servconf.h" 99 #include "uidswap.h" 100 #include "compat.h" 101 #include "cipher.h" 102 #include "digest.h" 103 #include "key.h" 104 #include "kex.h" 105 #include "myproposal.h" 106 #include "authfile.h" 107 #include "pathnames.h" 108 #include "atomicio.h" 109 #include "canohost.h" 110 #include "hostfile.h" 111 #include "auth.h" 112 #include "authfd.h" 113 #include "msg.h" 114 #include "dispatch.h" 115 #include "channels.h" 116 #include "session.h" 117 #include "monitor_mm.h" 118 #include "monitor.h" 119 #ifdef GSSAPI 120 #include "ssh-gss.h" 121 #endif 122 #include "monitor_wrap.h" 123 #include "roaming.h" 124 #include "ssh-sandbox.h" 125 #include "version.h" 126 127 #ifndef O_NOCTTY 128 #define O_NOCTTY 0 129 #endif 130 131 /* Re-exec fds */ 132 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 133 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 134 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 135 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 136 137 int myflag = 0; 138 139 140 extern char *__progname; 141 142 /* Server configuration options. */ 143 ServerOptions options; 144 145 /* Name of the server configuration file. */ 146 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 147 148 /* 149 * Debug mode flag. This can be set on the command line. If debug 150 * mode is enabled, extra debugging output will be sent to the system 151 * log, the daemon will not go to background, and will exit after processing 152 * the first connection. 153 */ 154 int debug_flag = 0; 155 156 /* Flag indicating that the daemon should only test the configuration and keys. */ 157 int test_flag = 0; 158 159 /* Flag indicating that the daemon is being started from inetd. */ 160 int inetd_flag = 0; 161 162 /* Flag indicating that sshd should not detach and become a daemon. */ 163 int no_daemon_flag = 0; 164 165 /* debug goes to stderr unless inetd_flag is set */ 166 int log_stderr = 0; 167 168 /* Saved arguments to main(). */ 169 char **saved_argv; 170 int saved_argc; 171 172 /* re-exec */ 173 int rexeced_flag = 0; 174 int rexec_flag = 1; 175 int rexec_argc = 0; 176 char **rexec_argv; 177 178 /* 179 * The sockets that the server is listening; this is used in the SIGHUP 180 * signal handler. 181 */ 182 #define MAX_LISTEN_SOCKS 16 183 int listen_socks[MAX_LISTEN_SOCKS]; 184 int num_listen_socks = 0; 185 186 /* 187 * the client's version string, passed by sshd2 in compat mode. if != NULL, 188 * sshd will skip the version-number exchange 189 */ 190 char *client_version_string = NULL; 191 char *server_version_string = NULL; 192 193 /* for rekeying XXX fixme */ 194 Kex *xxx_kex; 195 196 /* Daemon's agent connection */ 197 AuthenticationConnection *auth_conn = NULL; 198 int have_agent = 0; 199 200 /* 201 * Any really sensitive data in the application is contained in this 202 * structure. The idea is that this structure could be locked into memory so 203 * that the pages do not get written into swap. However, there are some 204 * problems. The private key contains BIGNUMs, and we do not (in principle) 205 * have access to the internals of them, and locking just the structure is 206 * not very useful. Currently, memory locking is not implemented. 207 */ 208 struct { 209 Key *server_key; /* ephemeral server key */ 210 Key *ssh1_host_key; /* ssh1 host key */ 211 Key **host_keys; /* all private host keys */ 212 Key **host_pubkeys; /* all public host keys */ 213 Key **host_certificates; /* all public host certificates */ 214 int have_ssh1_key; 215 int have_ssh2_key; 216 u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; 217 } sensitive_data; 218 219 /* 220 * Flag indicating whether the RSA server key needs to be regenerated. 221 * Is set in the SIGALRM handler and cleared when the key is regenerated. 222 */ 223 static volatile sig_atomic_t key_do_regen = 0; 224 225 /* This is set to true when a signal is received. */ 226 static volatile sig_atomic_t received_sighup = 0; 227 static volatile sig_atomic_t received_sigterm = 0; 228 229 /* session identifier, used by RSA-auth */ 230 u_char session_id[16]; 231 232 /* same for ssh2 */ 233 u_char *session_id2 = NULL; 234 u_int session_id2_len = 0; 235 236 /* record remote hostname or ip */ 237 u_int utmp_len = MAXHOSTNAMELEN; 238 239 /* options.max_startup sized array of fd ints */ 240 int *startup_pipes = NULL; 241 int startup_pipe; /* in child */ 242 243 /* variables used for privilege separation */ 244 int use_privsep = -1; 245 struct monitor *pmonitor = NULL; 246 int privsep_is_preauth = 1; 247 248 /* global authentication context */ 249 Authctxt *the_authctxt = NULL; 250 251 /* sshd_config buffer */ 252 Buffer cfg; 253 254 /* message to be displayed after login */ 255 Buffer loginmsg; 256 257 /* Unprivileged user */ 258 struct passwd *privsep_pw = NULL; 259 260 /* Prototypes for various functions defined later in this file. */ 261 void destroy_sensitive_data(void); 262 void demote_sensitive_data(void); 263 264 #ifdef WITH_SSH1 265 static void do_ssh1_kex(void); 266 #endif 267 static void do_ssh2_kex(void); 268 269 /* 270 * Close all listening sockets 271 */ 272 static void 273 close_listen_socks(void) 274 { 275 int i; 276 277 for (i = 0; i < num_listen_socks; i++) 278 close(listen_socks[i]); 279 num_listen_socks = -1; 280 } 281 282 static void 283 close_startup_pipes(void) 284 { 285 int i; 286 287 if (startup_pipes) 288 for (i = 0; i < options.max_startups; i++) 289 if (startup_pipes[i] != -1) 290 close(startup_pipes[i]); 291 } 292 293 /* 294 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 295 * the effect is to reread the configuration file (and to regenerate 296 * the server key). 297 */ 298 299 /*ARGSUSED*/ 300 static void 301 sighup_handler(int sig) 302 { 303 int save_errno = errno; 304 305 received_sighup = 1; 306 signal(SIGHUP, sighup_handler); 307 errno = save_errno; 308 } 309 310 /* 311 * Called from the main program after receiving SIGHUP. 312 * Restarts the server. 313 */ 314 static void 315 sighup_restart(void) 316 { 317 logit("Received SIGHUP; restarting."); 318 platform_pre_restart(); 319 close_listen_socks(); 320 close_startup_pipes(); 321 alarm(0); /* alarm timer persists across exec */ 322 signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 323 execv(saved_argv[0], saved_argv); 324 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 325 strerror(errno)); 326 exit(1); 327 } 328 329 /* 330 * Generic signal handler for terminating signals in the master daemon. 331 */ 332 /*ARGSUSED*/ 333 static void 334 sigterm_handler(int sig) 335 { 336 received_sigterm = sig; 337 } 338 339 /* 340 * SIGCHLD handler. This is called whenever a child dies. This will then 341 * reap any zombies left by exited children. 342 */ 343 /*ARGSUSED*/ 344 static void 345 main_sigchld_handler(int sig) 346 { 347 int save_errno = errno; 348 pid_t pid; 349 int status; 350 351 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 352 (pid < 0 && errno == EINTR)) 353 ; 354 355 signal(SIGCHLD, main_sigchld_handler); 356 errno = save_errno; 357 } 358 359 /* 360 * Signal handler for the alarm after the login grace period has expired. 361 */ 362 /*ARGSUSED*/ 363 static void 364 grace_alarm_handler(int sig) 365 { 366 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 367 kill(pmonitor->m_pid, SIGALRM); 368 369 /* 370 * Try to kill any processes that we have spawned, E.g. authorized 371 * keys command helpers. 372 */ 373 if (getpgid(0) == getpid()) { 374 signal(SIGTERM, SIG_IGN); 375 kill(0, SIGTERM); 376 } 377 378 /* Log error and exit. */ 379 sigdie("Timeout before authentication for %s", get_remote_ipaddr()); 380 } 381 382 /* 383 * Signal handler for the key regeneration alarm. Note that this 384 * alarm only occurs in the daemon waiting for connections, and it does not 385 * do anything with the private key or random state before forking. 386 * Thus there should be no concurrency control/asynchronous execution 387 * problems. 388 */ 389 static void 390 generate_ephemeral_server_key(void) 391 { 392 verbose("Generating %s%d bit RSA key.", 393 sensitive_data.server_key ? "new " : "", options.server_key_bits); 394 if (sensitive_data.server_key != NULL) 395 key_free(sensitive_data.server_key); 396 sensitive_data.server_key = key_generate(KEY_RSA1, 397 options.server_key_bits); 398 verbose("RSA key generation complete."); 399 400 arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 401 } 402 403 /*ARGSUSED*/ 404 static void 405 key_regeneration_alarm(int sig) 406 { 407 int save_errno = errno; 408 409 signal(SIGALRM, SIG_DFL); 410 errno = save_errno; 411 key_do_regen = 1; 412 } 413 414 static void 415 sshd_exchange_identification(int sock_in, int sock_out) 416 { 417 u_int i; 418 int mismatch; 419 int remote_major, remote_minor; 420 int major, minor; 421 char *s, *newline = "\n"; 422 char buf[256]; /* Must not be larger than remote_version. */ 423 char remote_version[256]; /* Must be at least as big as buf. */ 424 425 if ((options.protocol & SSH_PROTO_1) && 426 (options.protocol & SSH_PROTO_2)) { 427 major = PROTOCOL_MAJOR_1; 428 minor = 99; 429 } else if (options.protocol & SSH_PROTO_2) { 430 major = PROTOCOL_MAJOR_2; 431 minor = PROTOCOL_MINOR_2; 432 newline = "\r\n"; 433 } else { 434 major = PROTOCOL_MAJOR_1; 435 minor = PROTOCOL_MINOR_1; 436 } 437 438 xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s%s", 439 major, minor, SSH_RELEASE, 440 options.hpn_disabled ? "" : SSH_VERSION_HPN, 441 *options.version_addendum == '\0' ? "" : " ", 442 options.version_addendum, newline); 443 444 /* Send our protocol version identification. */ 445 if (roaming_atomicio(vwrite, sock_out, server_version_string, 446 strlen(server_version_string)) 447 != strlen(server_version_string)) { 448 logit("Could not write ident string to %s", get_remote_ipaddr()); 449 cleanup_exit(255); 450 } 451 452 /* Read other sides version identification. */ 453 memset(buf, 0, sizeof(buf)); 454 for (i = 0; i < sizeof(buf) - 1; i++) { 455 if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) { 456 logit("Did not receive identification string from %s", 457 get_remote_ipaddr()); 458 cleanup_exit(255); 459 } 460 if (buf[i] == '\r') { 461 buf[i] = 0; 462 /* Kludge for F-Secure Macintosh < 1.0.2 */ 463 if (i == 12 && 464 strncmp(buf, "SSH-1.5-W1.0", 12) == 0) 465 break; 466 continue; 467 } 468 if (buf[i] == '\n') { 469 buf[i] = 0; 470 break; 471 } 472 } 473 buf[sizeof(buf) - 1] = 0; 474 client_version_string = xstrdup(buf); 475 476 /* 477 * Check that the versions match. In future this might accept 478 * several versions and set appropriate flags to handle them. 479 */ 480 if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", 481 &remote_major, &remote_minor, remote_version) != 3) { 482 s = "Protocol mismatch.\n"; 483 (void) atomicio(vwrite, sock_out, s, strlen(s)); 484 logit("Bad protocol version identification '%.100s' " 485 "from %s port %d", client_version_string, 486 get_remote_ipaddr(), get_remote_port()); 487 close(sock_in); 488 close(sock_out); 489 cleanup_exit(255); 490 } 491 debug("Client protocol version %d.%d; client software version %.100s", 492 remote_major, remote_minor, remote_version); 493 logit("SSH: Server;Ltype: Version;Remote: %s-%d;Protocol: %d.%d;Client: %.100s", 494 get_remote_ipaddr(), get_remote_port(), 495 remote_major, remote_minor, remote_version); 496 497 compat_datafellows(remote_version); 498 499 if ((datafellows & SSH_BUG_PROBE) != 0) { 500 logit("probed from %s with %s. Don't panic.", 501 get_remote_ipaddr(), client_version_string); 502 cleanup_exit(255); 503 } 504 if ((datafellows & SSH_BUG_SCANNER) != 0) { 505 logit("scanned from %s with %s. Don't panic.", 506 get_remote_ipaddr(), client_version_string); 507 cleanup_exit(255); 508 } 509 if ((datafellows & SSH_BUG_RSASIGMD5) != 0) { 510 logit("Client version \"%.100s\" uses unsafe RSA signature " 511 "scheme; disabling use of RSA keys", remote_version); 512 } 513 if ((datafellows & SSH_BUG_DERIVEKEY) != 0) { 514 fatal("Client version \"%.100s\" uses unsafe key agreement; " 515 "refusing connection", remote_version); 516 } 517 518 mismatch = 0; 519 switch (remote_major) { 520 case 1: 521 if (remote_minor == 99) { 522 if (options.protocol & SSH_PROTO_2) 523 enable_compat20(); 524 else 525 mismatch = 1; 526 break; 527 } 528 if (!(options.protocol & SSH_PROTO_1)) { 529 mismatch = 1; 530 break; 531 } 532 if (remote_minor < 3) { 533 packet_disconnect("Your ssh version is too old and " 534 "is no longer supported. Please install a newer version."); 535 } else if (remote_minor == 3) { 536 /* note that this disables agent-forwarding */ 537 enable_compat13(); 538 } 539 break; 540 case 2: 541 if (options.protocol & SSH_PROTO_2) { 542 enable_compat20(); 543 break; 544 } 545 /* FALLTHROUGH */ 546 default: 547 mismatch = 1; 548 break; 549 } 550 chop(server_version_string); 551 debug("Local version string %.200s", server_version_string); 552 553 if (mismatch) { 554 s = "Protocol major versions differ.\n"; 555 (void) atomicio(vwrite, sock_out, s, strlen(s)); 556 close(sock_in); 557 close(sock_out); 558 logit("Protocol major versions differ for %s: %.200s vs. %.200s", 559 get_remote_ipaddr(), 560 server_version_string, client_version_string); 561 cleanup_exit(255); 562 } 563 } 564 565 /* Destroy the host and server keys. They will no longer be needed. */ 566 void 567 destroy_sensitive_data(void) 568 { 569 int i; 570 571 if (sensitive_data.server_key) { 572 key_free(sensitive_data.server_key); 573 sensitive_data.server_key = NULL; 574 } 575 for (i = 0; i < options.num_host_key_files; i++) { 576 if (sensitive_data.host_keys[i]) { 577 key_free(sensitive_data.host_keys[i]); 578 sensitive_data.host_keys[i] = NULL; 579 } 580 if (sensitive_data.host_certificates[i]) { 581 key_free(sensitive_data.host_certificates[i]); 582 sensitive_data.host_certificates[i] = NULL; 583 } 584 } 585 sensitive_data.ssh1_host_key = NULL; 586 explicit_bzero(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); 587 } 588 589 /* Demote private to public keys for network child */ 590 void 591 demote_sensitive_data(void) 592 { 593 Key *tmp; 594 int i; 595 596 if (sensitive_data.server_key) { 597 tmp = key_demote(sensitive_data.server_key); 598 key_free(sensitive_data.server_key); 599 sensitive_data.server_key = tmp; 600 } 601 602 for (i = 0; i < options.num_host_key_files; i++) { 603 if (sensitive_data.host_keys[i]) { 604 tmp = key_demote(sensitive_data.host_keys[i]); 605 key_free(sensitive_data.host_keys[i]); 606 sensitive_data.host_keys[i] = tmp; 607 if (tmp->type == KEY_RSA1) 608 sensitive_data.ssh1_host_key = tmp; 609 } 610 /* Certs do not need demotion */ 611 } 612 613 /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ 614 } 615 616 static void 617 privsep_preauth_child(void) 618 { 619 u_int32_t rnd[256]; 620 gid_t gidset[1]; 621 622 /* Enable challenge-response authentication for privilege separation */ 623 privsep_challenge_enable(); 624 625 #ifdef GSSAPI 626 /* Cache supported mechanism OIDs for later use */ 627 if (options.gss_authentication) 628 ssh_gssapi_prepare_supported_oids(); 629 #endif 630 631 arc4random_stir(); 632 arc4random_buf(rnd, sizeof(rnd)); 633 RAND_seed(rnd, sizeof(rnd)); 634 explicit_bzero(rnd, sizeof(rnd)); 635 636 /* Demote the private keys to public keys. */ 637 demote_sensitive_data(); 638 639 /* Change our root directory */ 640 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 641 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 642 strerror(errno)); 643 if (chdir("/") == -1) 644 fatal("chdir(\"/\"): %s", strerror(errno)); 645 646 /* Drop our privileges */ 647 debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, 648 (u_int)privsep_pw->pw_gid); 649 #if 0 650 /* XXX not ready, too heavy after chroot */ 651 do_setusercontext(privsep_pw); 652 #else 653 gidset[0] = privsep_pw->pw_gid; 654 if (setgroups(1, gidset) < 0) 655 fatal("setgroups: %.100s", strerror(errno)); 656 permanently_set_uid(privsep_pw); 657 #endif 658 } 659 660 static int 661 privsep_preauth(Authctxt *authctxt) 662 { 663 int status; 664 pid_t pid; 665 struct ssh_sandbox *box = NULL; 666 667 /* Set up unprivileged child process to deal with network data */ 668 pmonitor = monitor_init(); 669 /* Store a pointer to the kex for later rekeying */ 670 pmonitor->m_pkex = &xxx_kex; 671 672 if (use_privsep == PRIVSEP_ON) 673 box = ssh_sandbox_init(pmonitor); 674 pid = fork(); 675 if (pid == -1) { 676 fatal("fork of unprivileged child failed"); 677 } else if (pid != 0) { 678 debug2("Network child is on pid %ld", (long)pid); 679 680 pmonitor->m_pid = pid; 681 if (have_agent) 682 auth_conn = ssh_get_authentication_connection(); 683 if (box != NULL) 684 ssh_sandbox_parent_preauth(box, pid); 685 monitor_child_preauth(authctxt, pmonitor); 686 687 /* Sync memory */ 688 monitor_sync(pmonitor); 689 690 /* Wait for the child's exit status */ 691 while (waitpid(pid, &status, 0) < 0) { 692 if (errno == EINTR) 693 continue; 694 pmonitor->m_pid = -1; 695 fatal("%s: waitpid: %s", __func__, strerror(errno)); 696 } 697 privsep_is_preauth = 0; 698 pmonitor->m_pid = -1; 699 if (WIFEXITED(status)) { 700 if (WEXITSTATUS(status) != 0) 701 fatal("%s: preauth child exited with status %d", 702 __func__, WEXITSTATUS(status)); 703 } else if (WIFSIGNALED(status)) 704 fatal("%s: preauth child terminated by signal %d", 705 __func__, WTERMSIG(status)); 706 if (box != NULL) 707 ssh_sandbox_parent_finish(box); 708 return 1; 709 } else { 710 /* child */ 711 close(pmonitor->m_sendfd); 712 close(pmonitor->m_log_recvfd); 713 714 /* Arrange for logging to be sent to the monitor */ 715 set_log_handler(mm_log_handler, pmonitor); 716 717 /* Demote the child */ 718 if (getuid() == 0 || geteuid() == 0) 719 privsep_preauth_child(); 720 setproctitle("%s", "[net]"); 721 if (box != NULL) 722 ssh_sandbox_child(box); 723 724 return 0; 725 } 726 } 727 728 static void 729 privsep_postauth(Authctxt *authctxt) 730 { 731 u_int32_t rnd[256]; 732 733 #ifdef DISABLE_FD_PASSING 734 if (1) { 735 #else 736 if (authctxt->pw->pw_uid == 0 || options.use_login) { 737 #endif 738 /* File descriptor passing is broken or root login */ 739 use_privsep = 0; 740 goto skip; 741 } 742 743 /* New socket pair */ 744 monitor_reinit(pmonitor); 745 746 pmonitor->m_pid = fork(); 747 if (pmonitor->m_pid == -1) 748 fatal("fork of unprivileged child failed"); 749 else if (pmonitor->m_pid != 0) { 750 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 751 buffer_clear(&loginmsg); 752 monitor_child_postauth(pmonitor); 753 754 /* NEVERREACHED */ 755 exit(0); 756 } 757 758 /* child */ 759 760 close(pmonitor->m_sendfd); 761 pmonitor->m_sendfd = -1; 762 763 /* Demote the private keys to public keys. */ 764 demote_sensitive_data(); 765 766 arc4random_stir(); 767 arc4random_buf(rnd, sizeof(rnd)); 768 RAND_seed(rnd, sizeof(rnd)); 769 explicit_bzero(rnd, sizeof(rnd)); 770 771 /* Drop privileges */ 772 do_setusercontext(authctxt->pw); 773 774 skip: 775 /* It is safe now to apply the key state */ 776 monitor_apply_keystate(pmonitor); 777 778 /* 779 * Tell the packet layer that authentication was successful, since 780 * this information is not part of the key state. 781 */ 782 packet_set_authenticated(); 783 } 784 785 static char * 786 list_hostkey_types(void) 787 { 788 Buffer b; 789 const char *p; 790 char *ret; 791 int i; 792 Key *key; 793 794 buffer_init(&b); 795 for (i = 0; i < options.num_host_key_files; i++) { 796 key = sensitive_data.host_keys[i]; 797 if (key == NULL) 798 key = sensitive_data.host_pubkeys[i]; 799 if (key == NULL) 800 continue; 801 switch (key->type) { 802 case KEY_RSA: 803 case KEY_DSA: 804 case KEY_ECDSA: 805 case KEY_ED25519: 806 if (buffer_len(&b) > 0) 807 buffer_append(&b, ",", 1); 808 p = key_ssh_name(key); 809 buffer_append(&b, p, strlen(p)); 810 break; 811 } 812 /* If the private key has a cert peer, then list that too */ 813 key = sensitive_data.host_certificates[i]; 814 if (key == NULL) 815 continue; 816 switch (key->type) { 817 case KEY_RSA_CERT_V00: 818 case KEY_DSA_CERT_V00: 819 case KEY_RSA_CERT: 820 case KEY_DSA_CERT: 821 case KEY_ECDSA_CERT: 822 case KEY_ED25519_CERT: 823 if (buffer_len(&b) > 0) 824 buffer_append(&b, ",", 1); 825 p = key_ssh_name(key); 826 buffer_append(&b, p, strlen(p)); 827 break; 828 } 829 } 830 buffer_append(&b, "\0", 1); 831 ret = xstrdup(buffer_ptr(&b)); 832 buffer_free(&b); 833 debug("list_hostkey_types: %s", ret); 834 return ret; 835 } 836 837 static Key * 838 get_hostkey_by_type(int type, int need_private) 839 { 840 int i; 841 Key *key; 842 843 for (i = 0; i < options.num_host_key_files; i++) { 844 switch (type) { 845 case KEY_RSA_CERT_V00: 846 case KEY_DSA_CERT_V00: 847 case KEY_RSA_CERT: 848 case KEY_DSA_CERT: 849 case KEY_ECDSA_CERT: 850 case KEY_ED25519_CERT: 851 key = sensitive_data.host_certificates[i]; 852 break; 853 default: 854 key = sensitive_data.host_keys[i]; 855 if (key == NULL && !need_private) 856 key = sensitive_data.host_pubkeys[i]; 857 break; 858 } 859 if (key != NULL && key->type == type) 860 return need_private ? 861 sensitive_data.host_keys[i] : key; 862 } 863 return NULL; 864 } 865 866 Key * 867 get_hostkey_public_by_type(int type) 868 { 869 return get_hostkey_by_type(type, 0); 870 } 871 872 Key * 873 get_hostkey_private_by_type(int type) 874 { 875 return get_hostkey_by_type(type, 1); 876 } 877 878 Key * 879 get_hostkey_by_index(int ind) 880 { 881 if (ind < 0 || ind >= options.num_host_key_files) 882 return (NULL); 883 return (sensitive_data.host_keys[ind]); 884 } 885 886 Key * 887 get_hostkey_public_by_index(int ind) 888 { 889 if (ind < 0 || ind >= options.num_host_key_files) 890 return (NULL); 891 return (sensitive_data.host_pubkeys[ind]); 892 } 893 894 int 895 get_hostkey_index(Key *key) 896 { 897 int i; 898 899 for (i = 0; i < options.num_host_key_files; i++) { 900 if (key_is_cert(key)) { 901 if (key == sensitive_data.host_certificates[i]) 902 return (i); 903 } else { 904 if (key == sensitive_data.host_keys[i]) 905 return (i); 906 if (key == sensitive_data.host_pubkeys[i]) 907 return (i); 908 } 909 } 910 return (-1); 911 } 912 913 /* 914 * returns 1 if connection should be dropped, 0 otherwise. 915 * dropping starts at connection #max_startups_begin with a probability 916 * of (max_startups_rate/100). the probability increases linearly until 917 * all connections are dropped for startups > max_startups 918 */ 919 static int 920 drop_connection(int startups) 921 { 922 int p, r; 923 924 if (startups < options.max_startups_begin) 925 return 0; 926 if (startups >= options.max_startups) 927 return 1; 928 if (options.max_startups_rate == 100) 929 return 1; 930 931 p = 100 - options.max_startups_rate; 932 p *= startups - options.max_startups_begin; 933 p /= options.max_startups - options.max_startups_begin; 934 p += options.max_startups_rate; 935 r = arc4random_uniform(100); 936 937 debug("drop_connection: p %d, r %d", p, r); 938 return (r < p) ? 1 : 0; 939 } 940 941 static void 942 usage(void) 943 { 944 fprintf(stderr, "%s%s %s, %s\n", 945 SSH_RELEASE, SSH_VERSION_HPN, SSH_VERSION_DRAGONFLY, 946 #ifdef WITH_OPENSSL 947 SSLeay_version(SSLEAY_VERSION) 948 #else 949 "without OpenSSL" 950 #endif 951 ); 952 fprintf(stderr, 953 "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-c host_cert_file]\n" 954 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 955 " [-h host_key_file] [-k key_gen_time] [-o option] [-p port]\n" 956 " [-u len]\n" 957 ); 958 exit(1); 959 } 960 961 static void 962 send_rexec_state(int fd, Buffer *conf) 963 { 964 Buffer m; 965 966 debug3("%s: entering fd = %d config len %d", __func__, fd, 967 buffer_len(conf)); 968 969 /* 970 * Protocol from reexec master to child: 971 * string configuration 972 * u_int ephemeral_key_follows 973 * bignum e (only if ephemeral_key_follows == 1) 974 * bignum n " 975 * bignum d " 976 * bignum iqmp " 977 * bignum p " 978 * bignum q " 979 * string rngseed (only if OpenSSL is not self-seeded) 980 */ 981 buffer_init(&m); 982 buffer_put_cstring(&m, buffer_ptr(conf)); 983 984 #ifdef WITH_SSH1 985 if (sensitive_data.server_key != NULL && 986 sensitive_data.server_key->type == KEY_RSA1) { 987 buffer_put_int(&m, 1); 988 buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); 989 buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); 990 buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); 991 buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); 992 buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); 993 buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); 994 } else 995 #endif 996 buffer_put_int(&m, 0); 997 998 #ifndef OPENSSL_PRNG_ONLY 999 rexec_send_rng_seed(&m); 1000 #endif 1001 1002 if (ssh_msg_send(fd, 0, &m) == -1) 1003 fatal("%s: ssh_msg_send failed", __func__); 1004 1005 buffer_free(&m); 1006 1007 debug3("%s: done", __func__); 1008 } 1009 1010 static void 1011 recv_rexec_state(int fd, Buffer *conf) 1012 { 1013 Buffer m; 1014 char *cp; 1015 u_int len; 1016 1017 debug3("%s: entering fd = %d", __func__, fd); 1018 1019 buffer_init(&m); 1020 1021 if (ssh_msg_recv(fd, &m) == -1) 1022 fatal("%s: ssh_msg_recv failed", __func__); 1023 if (buffer_get_char(&m) != 0) 1024 fatal("%s: rexec version mismatch", __func__); 1025 1026 cp = buffer_get_string(&m, &len); 1027 if (conf != NULL) 1028 buffer_append(conf, cp, len + 1); 1029 free(cp); 1030 1031 if (buffer_get_int(&m)) { 1032 #ifdef WITH_SSH1 1033 if (sensitive_data.server_key != NULL) 1034 key_free(sensitive_data.server_key); 1035 sensitive_data.server_key = key_new_private(KEY_RSA1); 1036 buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); 1037 buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); 1038 buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); 1039 buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); 1040 buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); 1041 buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); 1042 if (rsa_generate_additional_parameters( 1043 sensitive_data.server_key->rsa) != 0) 1044 fatal("%s: rsa_generate_additional_parameters " 1045 "error", __func__); 1046 #else 1047 fatal("ssh1 not supported"); 1048 #endif 1049 } 1050 1051 #ifndef OPENSSL_PRNG_ONLY 1052 rexec_recv_rng_seed(&m); 1053 #endif 1054 1055 buffer_free(&m); 1056 1057 debug3("%s: done", __func__); 1058 } 1059 1060 /* Accept a connection from inetd */ 1061 static void 1062 server_accept_inetd(int *sock_in, int *sock_out) 1063 { 1064 int fd; 1065 1066 startup_pipe = -1; 1067 if (rexeced_flag) { 1068 close(REEXEC_CONFIG_PASS_FD); 1069 *sock_in = *sock_out = dup(STDIN_FILENO); 1070 if (!debug_flag) { 1071 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1072 close(REEXEC_STARTUP_PIPE_FD); 1073 } 1074 } else { 1075 *sock_in = dup(STDIN_FILENO); 1076 *sock_out = dup(STDOUT_FILENO); 1077 } 1078 /* 1079 * We intentionally do not close the descriptors 0, 1, and 2 1080 * as our code for setting the descriptors won't work if 1081 * ttyfd happens to be one of those. 1082 */ 1083 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1084 dup2(fd, STDIN_FILENO); 1085 dup2(fd, STDOUT_FILENO); 1086 if (!log_stderr) 1087 dup2(fd, STDERR_FILENO); 1088 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 1089 close(fd); 1090 } 1091 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1092 } 1093 1094 /* 1095 * Listen for TCP connections 1096 */ 1097 static void 1098 server_listen(void) 1099 { 1100 int ret, listen_sock, on = 1; 1101 struct addrinfo *ai; 1102 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1103 int socksize; 1104 int socksizelen = sizeof(int); 1105 1106 for (ai = options.listen_addrs; ai; ai = ai->ai_next) { 1107 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1108 continue; 1109 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1110 fatal("Too many listen sockets. " 1111 "Enlarge MAX_LISTEN_SOCKS"); 1112 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1113 ntop, sizeof(ntop), strport, sizeof(strport), 1114 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1115 error("getnameinfo failed: %.100s", 1116 ssh_gai_strerror(ret)); 1117 continue; 1118 } 1119 /* Create socket for listening. */ 1120 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1121 ai->ai_protocol); 1122 if (listen_sock < 0) { 1123 /* kernel may not support ipv6 */ 1124 verbose("socket: %.100s", strerror(errno)); 1125 continue; 1126 } 1127 if (set_nonblock(listen_sock) == -1) { 1128 close(listen_sock); 1129 continue; 1130 } 1131 /* 1132 * Set socket options. 1133 * Allow local port reuse in TIME_WAIT. 1134 */ 1135 if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, 1136 &on, sizeof(on)) == -1) 1137 error("setsockopt SO_REUSEADDR: %s", strerror(errno)); 1138 1139 /* Only communicate in IPv6 over AF_INET6 sockets. */ 1140 if (ai->ai_family == AF_INET6) 1141 sock_set_v6only(listen_sock); 1142 1143 debug("Bind to port %s on %s.", strport, ntop); 1144 1145 getsockopt(listen_sock, SOL_SOCKET, SO_RCVBUF, 1146 &socksize, &socksizelen); 1147 debug("Server TCP RWIN socket size: %d", socksize); 1148 debug("HPN Buffer Size: %d", options.hpn_buffer_size); 1149 1150 /* Bind the socket to the desired port. */ 1151 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { 1152 error("Bind to port %s on %s failed: %.200s.", 1153 strport, ntop, strerror(errno)); 1154 close(listen_sock); 1155 continue; 1156 } 1157 listen_socks[num_listen_socks] = listen_sock; 1158 num_listen_socks++; 1159 1160 /* Start listening on the port. */ 1161 if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) 1162 fatal("listen on [%s]:%s: %.100s", 1163 ntop, strport, strerror(errno)); 1164 logit("Server listening on %s port %s.", ntop, strport); 1165 } 1166 freeaddrinfo(options.listen_addrs); 1167 1168 if (!num_listen_socks) 1169 fatal("Cannot bind any address."); 1170 } 1171 1172 /* 1173 * The main TCP accept loop. Note that, for the non-debug case, returns 1174 * from this function are in a forked subprocess. 1175 */ 1176 static void 1177 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1178 { 1179 fd_set *fdset; 1180 int i, j, ret, maxfd; 1181 int key_used = 0, startups = 0; 1182 int startup_p[2] = { -1 , -1 }; 1183 struct sockaddr_storage from; 1184 socklen_t fromlen; 1185 pid_t pid; 1186 u_char rnd[256]; 1187 1188 /* setup fd set for accept */ 1189 fdset = NULL; 1190 maxfd = 0; 1191 for (i = 0; i < num_listen_socks; i++) 1192 if (listen_socks[i] > maxfd) 1193 maxfd = listen_socks[i]; 1194 /* pipes connected to unauthenticated childs */ 1195 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1196 for (i = 0; i < options.max_startups; i++) 1197 startup_pipes[i] = -1; 1198 1199 /* 1200 * Stay listening for connections until the system crashes or 1201 * the daemon is killed with a signal. 1202 */ 1203 for (;;) { 1204 if (received_sighup) 1205 sighup_restart(); 1206 if (fdset != NULL) 1207 free(fdset); 1208 fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), 1209 sizeof(fd_mask)); 1210 1211 for (i = 0; i < num_listen_socks; i++) 1212 FD_SET(listen_socks[i], fdset); 1213 for (i = 0; i < options.max_startups; i++) 1214 if (startup_pipes[i] != -1) 1215 FD_SET(startup_pipes[i], fdset); 1216 1217 /* Wait in select until there is a connection. */ 1218 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1219 if (ret < 0 && errno != EINTR) 1220 error("select: %.100s", strerror(errno)); 1221 if (received_sigterm) { 1222 logit("Received signal %d; terminating.", 1223 (int) received_sigterm); 1224 close_listen_socks(); 1225 unlink(options.pid_file); 1226 exit(received_sigterm == SIGTERM ? 0 : 255); 1227 } 1228 if (key_used && key_do_regen) { 1229 generate_ephemeral_server_key(); 1230 key_used = 0; 1231 key_do_regen = 0; 1232 } 1233 if (ret < 0) 1234 continue; 1235 1236 for (i = 0; i < options.max_startups; i++) 1237 if (startup_pipes[i] != -1 && 1238 FD_ISSET(startup_pipes[i], fdset)) { 1239 /* 1240 * the read end of the pipe is ready 1241 * if the child has closed the pipe 1242 * after successful authentication 1243 * or if the child has died 1244 */ 1245 close(startup_pipes[i]); 1246 startup_pipes[i] = -1; 1247 startups--; 1248 } 1249 for (i = 0; i < num_listen_socks; i++) { 1250 if (!FD_ISSET(listen_socks[i], fdset)) 1251 continue; 1252 fromlen = sizeof(from); 1253 *newsock = accept(listen_socks[i], 1254 (struct sockaddr *)&from, &fromlen); 1255 if (*newsock < 0) { 1256 if (errno != EINTR && errno != EWOULDBLOCK && 1257 errno != ECONNABORTED && errno != EAGAIN) 1258 error("accept: %.100s", 1259 strerror(errno)); 1260 if (errno == EMFILE || errno == ENFILE) 1261 usleep(100 * 1000); 1262 continue; 1263 } 1264 if (unset_nonblock(*newsock) == -1) { 1265 close(*newsock); 1266 continue; 1267 } 1268 if (drop_connection(startups) == 1) { 1269 debug("drop connection #%d", startups); 1270 close(*newsock); 1271 continue; 1272 } 1273 if (pipe(startup_p) == -1) { 1274 close(*newsock); 1275 continue; 1276 } 1277 1278 if (rexec_flag && socketpair(AF_UNIX, 1279 SOCK_STREAM, 0, config_s) == -1) { 1280 error("reexec socketpair: %s", 1281 strerror(errno)); 1282 close(*newsock); 1283 close(startup_p[0]); 1284 close(startup_p[1]); 1285 continue; 1286 } 1287 1288 for (j = 0; j < options.max_startups; j++) 1289 if (startup_pipes[j] == -1) { 1290 startup_pipes[j] = startup_p[0]; 1291 if (maxfd < startup_p[0]) 1292 maxfd = startup_p[0]; 1293 startups++; 1294 break; 1295 } 1296 1297 /* 1298 * Got connection. Fork a child to handle it, unless 1299 * we are in debugging mode. 1300 */ 1301 if (debug_flag) { 1302 /* 1303 * In debugging mode. Close the listening 1304 * socket, and start processing the 1305 * connection without forking. 1306 */ 1307 debug("Server will not fork when running in debugging mode."); 1308 close_listen_socks(); 1309 *sock_in = *newsock; 1310 *sock_out = *newsock; 1311 close(startup_p[0]); 1312 close(startup_p[1]); 1313 startup_pipe = -1; 1314 pid = getpid(); 1315 if (rexec_flag) { 1316 send_rexec_state(config_s[0], 1317 &cfg); 1318 close(config_s[0]); 1319 } 1320 break; 1321 } 1322 1323 /* 1324 * Normal production daemon. Fork, and have 1325 * the child process the connection. The 1326 * parent continues listening. 1327 */ 1328 platform_pre_fork(); 1329 if ((pid = fork()) == 0) { 1330 /* 1331 * Child. Close the listening and 1332 * max_startup sockets. Start using 1333 * the accepted socket. Reinitialize 1334 * logging (since our pid has changed). 1335 * We break out of the loop to handle 1336 * the connection. 1337 */ 1338 platform_post_fork_child(); 1339 startup_pipe = startup_p[1]; 1340 close_startup_pipes(); 1341 close_listen_socks(); 1342 *sock_in = *newsock; 1343 *sock_out = *newsock; 1344 log_init(__progname, 1345 options.log_level, 1346 options.log_facility, 1347 log_stderr); 1348 if (rexec_flag) 1349 close(config_s[0]); 1350 break; 1351 } 1352 1353 /* Parent. Stay in the loop. */ 1354 platform_post_fork_parent(pid); 1355 if (pid < 0) 1356 error("fork: %.100s", strerror(errno)); 1357 else 1358 debug("Forked child %ld.", (long)pid); 1359 1360 close(startup_p[1]); 1361 1362 if (rexec_flag) { 1363 send_rexec_state(config_s[0], &cfg); 1364 close(config_s[0]); 1365 close(config_s[1]); 1366 } 1367 1368 /* 1369 * Mark that the key has been used (it 1370 * was "given" to the child). 1371 */ 1372 if ((options.protocol & SSH_PROTO_1) && 1373 key_used == 0) { 1374 /* Schedule server key regeneration alarm. */ 1375 signal(SIGALRM, key_regeneration_alarm); 1376 alarm(options.key_regeneration_time); 1377 key_used = 1; 1378 } 1379 1380 close(*newsock); 1381 1382 /* 1383 * Ensure that our random state differs 1384 * from that of the child 1385 */ 1386 arc4random_stir(); 1387 arc4random_buf(rnd, sizeof(rnd)); 1388 RAND_seed(rnd, sizeof(rnd)); 1389 explicit_bzero(rnd, sizeof(rnd)); 1390 } 1391 1392 /* child process check (or debug mode) */ 1393 if (num_listen_socks < 0) 1394 break; 1395 } 1396 } 1397 1398 1399 /* 1400 * Main program for the daemon. 1401 */ 1402 int 1403 main(int ac, char **av) 1404 { 1405 extern char *optarg; 1406 extern int optind; 1407 int opt, i, j, on = 1; 1408 int sock_in = -1, sock_out = -1, newsock = -1; 1409 const char *remote_ip; 1410 int remote_port; 1411 char *line, *logfile = NULL; 1412 int config_s[2] = { -1 , -1 }; 1413 u_int n; 1414 u_int64_t ibytes, obytes; 1415 mode_t new_umask; 1416 Key *key; 1417 Key *pubkey; 1418 int keytype; 1419 Authctxt *authctxt; 1420 struct connection_info *connection_info = get_connection_info(0, 0); 1421 1422 #ifdef HAVE_SECUREWARE 1423 (void)set_auth_parameters(ac, av); 1424 #endif 1425 __progname = ssh_get_progname(av[0]); 1426 1427 /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ 1428 saved_argc = ac; 1429 rexec_argc = ac; 1430 saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); 1431 for (i = 0; i < ac; i++) 1432 saved_argv[i] = xstrdup(av[i]); 1433 saved_argv[i] = NULL; 1434 1435 #ifndef HAVE_SETPROCTITLE 1436 /* Prepare for later setproctitle emulation */ 1437 compat_init_setproctitle(ac, av); 1438 av = saved_argv; 1439 #endif 1440 1441 if (geteuid() == 0 && setgroups(0, NULL) == -1) 1442 debug("setgroups(): %.200s", strerror(errno)); 1443 1444 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1445 sanitise_stdfd(); 1446 1447 /* Initialize configuration options to their default values. */ 1448 initialize_server_options(&options); 1449 1450 /* Parse command-line arguments. */ 1451 while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeE:iqrtQRT46")) != -1) { 1452 switch (opt) { 1453 case '4': 1454 options.address_family = AF_INET; 1455 break; 1456 case '6': 1457 options.address_family = AF_INET6; 1458 break; 1459 case 'f': 1460 config_file_name = optarg; 1461 break; 1462 case 'c': 1463 if (options.num_host_cert_files >= MAX_HOSTCERTS) { 1464 fprintf(stderr, "too many host certificates.\n"); 1465 exit(1); 1466 } 1467 options.host_cert_files[options.num_host_cert_files++] = 1468 derelativise_path(optarg); 1469 break; 1470 case 'd': 1471 if (debug_flag == 0) { 1472 debug_flag = 1; 1473 options.log_level = SYSLOG_LEVEL_DEBUG1; 1474 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1475 options.log_level++; 1476 break; 1477 case 'D': 1478 no_daemon_flag = 1; 1479 break; 1480 case 'E': 1481 logfile = xstrdup(optarg); 1482 /* FALLTHROUGH */ 1483 case 'e': 1484 log_stderr = 1; 1485 break; 1486 case 'i': 1487 inetd_flag = 1; 1488 break; 1489 case 'r': 1490 rexec_flag = 0; 1491 break; 1492 case 'R': 1493 rexeced_flag = 1; 1494 inetd_flag = 1; 1495 break; 1496 case 'Q': 1497 /* ignored */ 1498 break; 1499 case 'q': 1500 options.log_level = SYSLOG_LEVEL_QUIET; 1501 break; 1502 case 'b': 1503 options.server_key_bits = (int)strtonum(optarg, 256, 1504 32768, NULL); 1505 break; 1506 case 'p': 1507 options.ports_from_cmdline = 1; 1508 if (options.num_ports >= MAX_PORTS) { 1509 fprintf(stderr, "too many ports.\n"); 1510 exit(1); 1511 } 1512 options.ports[options.num_ports++] = a2port(optarg); 1513 if (options.ports[options.num_ports-1] <= 0) { 1514 fprintf(stderr, "Bad port number.\n"); 1515 exit(1); 1516 } 1517 break; 1518 case 'g': 1519 if ((options.login_grace_time = convtime(optarg)) == -1) { 1520 fprintf(stderr, "Invalid login grace time.\n"); 1521 exit(1); 1522 } 1523 break; 1524 case 'k': 1525 if ((options.key_regeneration_time = convtime(optarg)) == -1) { 1526 fprintf(stderr, "Invalid key regeneration interval.\n"); 1527 exit(1); 1528 } 1529 break; 1530 case 'h': 1531 if (options.num_host_key_files >= MAX_HOSTKEYS) { 1532 fprintf(stderr, "too many host keys.\n"); 1533 exit(1); 1534 } 1535 options.host_key_files[options.num_host_key_files++] = 1536 derelativise_path(optarg); 1537 break; 1538 case 't': 1539 test_flag = 1; 1540 break; 1541 case 'T': 1542 test_flag = 2; 1543 break; 1544 case 'C': 1545 if (parse_server_match_testspec(connection_info, 1546 optarg) == -1) 1547 exit(1); 1548 break; 1549 case 'u': 1550 utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); 1551 if (utmp_len > MAXHOSTNAMELEN) { 1552 fprintf(stderr, "Invalid utmp length.\n"); 1553 exit(1); 1554 } 1555 break; 1556 case 'o': 1557 line = xstrdup(optarg); 1558 if (process_server_config_line(&options, line, 1559 "command-line", 0, NULL, NULL) != 0) 1560 exit(1); 1561 free(line); 1562 break; 1563 case '?': 1564 default: 1565 usage(); 1566 break; 1567 } 1568 } 1569 if (rexeced_flag || inetd_flag) 1570 rexec_flag = 0; 1571 if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/'))) 1572 fatal("sshd re-exec requires execution with an absolute path"); 1573 if (rexeced_flag) 1574 closefrom(REEXEC_MIN_FREE_FD); 1575 else 1576 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1577 1578 #ifdef WITH_OPENSSL 1579 OpenSSL_add_all_algorithms(); 1580 #endif 1581 1582 /* If requested, redirect the logs to the specified logfile. */ 1583 if (logfile != NULL) { 1584 log_redirect_stderr_to(logfile); 1585 free(logfile); 1586 } 1587 /* 1588 * Force logging to stderr until we have loaded the private host 1589 * key (unless started from inetd) 1590 */ 1591 log_init(__progname, 1592 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1593 SYSLOG_LEVEL_INFO : options.log_level, 1594 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1595 SYSLOG_FACILITY_AUTH : options.log_facility, 1596 log_stderr || !inetd_flag); 1597 1598 /* 1599 * Unset KRB5CCNAME, otherwise the user's session may inherit it from 1600 * root's environment 1601 */ 1602 if (getenv("KRB5CCNAME") != NULL) 1603 (void) unsetenv("KRB5CCNAME"); 1604 1605 #ifdef _UNICOS 1606 /* Cray can define user privs drop all privs now! 1607 * Not needed on PRIV_SU systems! 1608 */ 1609 drop_cray_privs(); 1610 #endif 1611 1612 sensitive_data.server_key = NULL; 1613 sensitive_data.ssh1_host_key = NULL; 1614 sensitive_data.have_ssh1_key = 0; 1615 sensitive_data.have_ssh2_key = 0; 1616 1617 /* 1618 * If we're doing an extended config test, make sure we have all of 1619 * the parameters we need. If we're not doing an extended test, 1620 * do not silently ignore connection test params. 1621 */ 1622 if (test_flag >= 2 && server_match_spec_complete(connection_info) == 0) 1623 fatal("user, host and addr are all required when testing " 1624 "Match configs"); 1625 if (test_flag < 2 && server_match_spec_complete(connection_info) >= 0) 1626 fatal("Config test connection parameter (-C) provided without " 1627 "test mode (-T)"); 1628 1629 /* Fetch our configuration */ 1630 buffer_init(&cfg); 1631 if (rexeced_flag) 1632 recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); 1633 else 1634 load_server_config(config_file_name, &cfg); 1635 1636 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1637 &cfg, NULL); 1638 1639 seed_rng(); 1640 1641 /* Fill in default values for those options not explicitly set. */ 1642 fill_default_server_options(&options); 1643 1644 /* challenge-response is implemented via keyboard interactive */ 1645 if (options.challenge_response_authentication) 1646 options.kbd_interactive_authentication = 1; 1647 1648 /* Check that options are sensible */ 1649 if (options.authorized_keys_command_user == NULL && 1650 (options.authorized_keys_command != NULL && 1651 strcasecmp(options.authorized_keys_command, "none") != 0)) 1652 fatal("AuthorizedKeysCommand set without " 1653 "AuthorizedKeysCommandUser"); 1654 1655 /* 1656 * Check whether there is any path through configured auth methods. 1657 * Unfortunately it is not possible to verify this generally before 1658 * daemonisation in the presence of Match block, but this catches 1659 * and warns for trivial misconfigurations that could break login. 1660 */ 1661 if (options.num_auth_methods != 0) { 1662 if ((options.protocol & SSH_PROTO_1)) 1663 fatal("AuthenticationMethods is not supported with " 1664 "SSH protocol 1"); 1665 for (n = 0; n < options.num_auth_methods; n++) { 1666 if (auth2_methods_valid(options.auth_methods[n], 1667 1) == 0) 1668 break; 1669 } 1670 if (n >= options.num_auth_methods) 1671 fatal("AuthenticationMethods cannot be satisfied by " 1672 "enabled authentication methods"); 1673 } 1674 1675 /* set default channel AF */ 1676 channel_set_af(options.address_family); 1677 1678 /* Check that there are no remaining arguments. */ 1679 if (optind < ac) { 1680 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1681 exit(1); 1682 } 1683 1684 debug("sshd version %s, %s", SSH_VERSION, 1685 #ifdef WITH_OPENSSL 1686 SSLeay_version(SSLEAY_VERSION) 1687 #else 1688 "without OpenSSL" 1689 #endif 1690 ); 1691 1692 /* Store privilege separation user for later use if required. */ 1693 if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { 1694 if (use_privsep || options.kerberos_authentication) 1695 fatal("Privilege separation user %s does not exist", 1696 SSH_PRIVSEP_USER); 1697 } else { 1698 explicit_bzero(privsep_pw->pw_passwd, 1699 strlen(privsep_pw->pw_passwd)); 1700 privsep_pw = pwcopy(privsep_pw); 1701 free(privsep_pw->pw_passwd); 1702 privsep_pw->pw_passwd = xstrdup("*"); 1703 } 1704 endpwent(); 1705 1706 /* load host keys */ 1707 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1708 sizeof(Key *)); 1709 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1710 sizeof(Key *)); 1711 for (i = 0; i < options.num_host_key_files; i++) { 1712 sensitive_data.host_keys[i] = NULL; 1713 sensitive_data.host_pubkeys[i] = NULL; 1714 } 1715 1716 if (options.host_key_agent) { 1717 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1718 setenv(SSH_AUTHSOCKET_ENV_NAME, 1719 options.host_key_agent, 1); 1720 have_agent = ssh_agent_present(); 1721 } 1722 1723 for (i = 0; i < options.num_host_key_files; i++) { 1724 key = key_load_private(options.host_key_files[i], "", NULL); 1725 pubkey = key_load_public(options.host_key_files[i], NULL); 1726 sensitive_data.host_keys[i] = key; 1727 sensitive_data.host_pubkeys[i] = pubkey; 1728 1729 if (key == NULL && pubkey != NULL && pubkey->type != KEY_RSA1 && 1730 have_agent) { 1731 debug("will rely on agent for hostkey %s", 1732 options.host_key_files[i]); 1733 keytype = pubkey->type; 1734 } else if (key != NULL) { 1735 keytype = key->type; 1736 } else { 1737 error("Could not load host key: %s", 1738 options.host_key_files[i]); 1739 sensitive_data.host_keys[i] = NULL; 1740 sensitive_data.host_pubkeys[i] = NULL; 1741 continue; 1742 } 1743 1744 switch (keytype) { 1745 case KEY_RSA1: 1746 sensitive_data.ssh1_host_key = key; 1747 sensitive_data.have_ssh1_key = 1; 1748 break; 1749 case KEY_RSA: 1750 case KEY_DSA: 1751 case KEY_ECDSA: 1752 case KEY_ED25519: 1753 sensitive_data.have_ssh2_key = 1; 1754 break; 1755 } 1756 debug("private host key: #%d type %d %s", i, keytype, 1757 key_type(key ? key : pubkey)); 1758 } 1759 if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { 1760 logit("Disabling protocol version 1. Could not load host key"); 1761 options.protocol &= ~SSH_PROTO_1; 1762 } 1763 if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { 1764 logit("Disabling protocol version 2. Could not load host key"); 1765 options.protocol &= ~SSH_PROTO_2; 1766 } 1767 if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { 1768 logit("sshd: no hostkeys available -- exiting."); 1769 exit(1); 1770 } 1771 1772 /* 1773 * Load certificates. They are stored in an array at identical 1774 * indices to the public keys that they relate to. 1775 */ 1776 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1777 sizeof(Key *)); 1778 for (i = 0; i < options.num_host_key_files; i++) 1779 sensitive_data.host_certificates[i] = NULL; 1780 1781 for (i = 0; i < options.num_host_cert_files; i++) { 1782 key = key_load_public(options.host_cert_files[i], NULL); 1783 if (key == NULL) { 1784 error("Could not load host certificate: %s", 1785 options.host_cert_files[i]); 1786 continue; 1787 } 1788 if (!key_is_cert(key)) { 1789 error("Certificate file is not a certificate: %s", 1790 options.host_cert_files[i]); 1791 key_free(key); 1792 continue; 1793 } 1794 /* Find matching private key */ 1795 for (j = 0; j < options.num_host_key_files; j++) { 1796 if (key_equal_public(key, 1797 sensitive_data.host_keys[j])) { 1798 sensitive_data.host_certificates[j] = key; 1799 break; 1800 } 1801 } 1802 if (j >= options.num_host_key_files) { 1803 error("No matching private key for certificate: %s", 1804 options.host_cert_files[i]); 1805 key_free(key); 1806 continue; 1807 } 1808 sensitive_data.host_certificates[j] = key; 1809 debug("host certificate: #%d type %d %s", j, key->type, 1810 key_type(key)); 1811 } 1812 1813 #ifdef WITH_SSH1 1814 /* Check certain values for sanity. */ 1815 if (options.protocol & SSH_PROTO_1) { 1816 if (options.server_key_bits < 512 || 1817 options.server_key_bits > 32768) { 1818 fprintf(stderr, "Bad server key size.\n"); 1819 exit(1); 1820 } 1821 /* 1822 * Check that server and host key lengths differ sufficiently. This 1823 * is necessary to make double encryption work with rsaref. Oh, I 1824 * hate software patents. I dont know if this can go? Niels 1825 */ 1826 if (options.server_key_bits > 1827 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - 1828 SSH_KEY_BITS_RESERVED && options.server_key_bits < 1829 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1830 SSH_KEY_BITS_RESERVED) { 1831 options.server_key_bits = 1832 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 1833 SSH_KEY_BITS_RESERVED; 1834 debug("Forcing server key to %d bits to make it differ from host key.", 1835 options.server_key_bits); 1836 } 1837 } 1838 #endif 1839 1840 if (use_privsep) { 1841 struct stat st; 1842 1843 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1844 (S_ISDIR(st.st_mode) == 0)) 1845 fatal("Missing privilege separation directory: %s", 1846 _PATH_PRIVSEP_CHROOT_DIR); 1847 1848 #ifdef HAVE_CYGWIN 1849 if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && 1850 (st.st_uid != getuid () || 1851 (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) 1852 #else 1853 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1854 #endif 1855 fatal("%s must be owned by root and not group or " 1856 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1857 } 1858 1859 if (test_flag > 1) { 1860 if (server_match_spec_complete(connection_info) == 1) 1861 parse_server_match_config(&options, connection_info); 1862 dump_config(&options); 1863 } 1864 1865 /* Configuration looks good, so exit if in test mode. */ 1866 if (test_flag) 1867 exit(0); 1868 1869 /* 1870 * Clear out any supplemental groups we may have inherited. This 1871 * prevents inadvertent creation of files with bad modes (in the 1872 * portable version at least, it's certainly possible for PAM 1873 * to create a file, and we can't control the code in every 1874 * module which might be used). 1875 */ 1876 if (setgroups(0, NULL) < 0) 1877 debug("setgroups() failed: %.200s", strerror(errno)); 1878 1879 if (rexec_flag) { 1880 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1881 for (i = 0; i < rexec_argc; i++) { 1882 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1883 rexec_argv[i] = saved_argv[i]; 1884 } 1885 rexec_argv[rexec_argc] = "-R"; 1886 rexec_argv[rexec_argc + 1] = NULL; 1887 } 1888 1889 /* Ensure that umask disallows at least group and world write */ 1890 new_umask = umask(0077) | 0022; 1891 (void) umask(new_umask); 1892 1893 /* Initialize the log (it is reinitialized below in case we forked). */ 1894 if (debug_flag && (!inetd_flag || rexeced_flag)) 1895 log_stderr = 1; 1896 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1897 1898 /* 1899 * If not in debugging mode, and not started from inetd, disconnect 1900 * from the controlling terminal, and fork. The original process 1901 * exits. 1902 */ 1903 if (!(debug_flag || inetd_flag || no_daemon_flag)) { 1904 #ifdef TIOCNOTTY 1905 int fd; 1906 #endif /* TIOCNOTTY */ 1907 if (daemon(0, 0) < 0) 1908 fatal("daemon() failed: %.200s", strerror(errno)); 1909 1910 /* Disconnect from the controlling tty. */ 1911 #ifdef TIOCNOTTY 1912 fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); 1913 if (fd >= 0) { 1914 (void) ioctl(fd, TIOCNOTTY, NULL); 1915 close(fd); 1916 } 1917 #endif /* TIOCNOTTY */ 1918 } 1919 /* Reinitialize the log (because of the fork above). */ 1920 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1921 1922 /* Chdir to the root directory so that the current disk can be 1923 unmounted if desired. */ 1924 if (chdir("/") == -1) 1925 error("chdir(\"/\"): %s", strerror(errno)); 1926 1927 /* ignore SIGPIPE */ 1928 signal(SIGPIPE, SIG_IGN); 1929 1930 /* Get a connection, either from inetd or a listening TCP socket */ 1931 if (inetd_flag) { 1932 server_accept_inetd(&sock_in, &sock_out); 1933 } else { 1934 platform_pre_listen(); 1935 server_listen(); 1936 1937 if (options.protocol & SSH_PROTO_1) 1938 generate_ephemeral_server_key(); 1939 1940 signal(SIGHUP, sighup_handler); 1941 signal(SIGCHLD, main_sigchld_handler); 1942 signal(SIGTERM, sigterm_handler); 1943 signal(SIGQUIT, sigterm_handler); 1944 1945 /* 1946 * Write out the pid file after the sigterm handler 1947 * is setup and the listen sockets are bound 1948 */ 1949 if (!debug_flag) { 1950 FILE *f = fopen(options.pid_file, "w"); 1951 1952 if (f == NULL) { 1953 error("Couldn't create pid file \"%s\": %s", 1954 options.pid_file, strerror(errno)); 1955 } else { 1956 fprintf(f, "%ld\n", (long) getpid()); 1957 fclose(f); 1958 } 1959 } 1960 1961 /* Accept a connection and return in a forked child */ 1962 server_accept_loop(&sock_in, &sock_out, 1963 &newsock, config_s); 1964 } 1965 1966 /* This is the child processing a new connection. */ 1967 setproctitle("%s", "[accepted]"); 1968 1969 /* 1970 * Initialize the resolver. This may not happen automatically 1971 * before privsep chroot(). 1972 */ 1973 if ((_res.options & RES_INIT) == 0) { 1974 debug("res_init()"); 1975 res_init(); 1976 } 1977 1978 /* 1979 * Create a new session and process group since the 4.4BSD 1980 * setlogin() affects the entire process group. We don't 1981 * want the child to be able to affect the parent. 1982 */ 1983 #if !defined(SSHD_ACQUIRES_CTTY) 1984 /* 1985 * If setsid is called, on some platforms sshd will later acquire a 1986 * controlling terminal which will result in "could not set 1987 * controlling tty" errors. 1988 */ 1989 if (!debug_flag && !inetd_flag && setsid() < 0) 1990 error("setsid: %.100s", strerror(errno)); 1991 #endif 1992 1993 if (rexec_flag) { 1994 int fd; 1995 1996 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1997 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1998 dup2(newsock, STDIN_FILENO); 1999 dup2(STDIN_FILENO, STDOUT_FILENO); 2000 if (startup_pipe == -1) 2001 close(REEXEC_STARTUP_PIPE_FD); 2002 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 2003 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 2004 close(startup_pipe); 2005 startup_pipe = REEXEC_STARTUP_PIPE_FD; 2006 } 2007 2008 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 2009 close(config_s[1]); 2010 2011 execv(rexec_argv[0], rexec_argv); 2012 2013 /* Reexec has failed, fall back and continue */ 2014 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 2015 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 2016 log_init(__progname, options.log_level, 2017 options.log_facility, log_stderr); 2018 2019 /* Clean up fds */ 2020 close(REEXEC_CONFIG_PASS_FD); 2021 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2022 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 2023 dup2(fd, STDIN_FILENO); 2024 dup2(fd, STDOUT_FILENO); 2025 if (fd > STDERR_FILENO) 2026 close(fd); 2027 } 2028 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2029 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2030 } 2031 2032 /* Executed child processes don't need these. */ 2033 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2034 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2035 2036 /* 2037 * Disable the key regeneration alarm. We will not regenerate the 2038 * key since we are no longer in a position to give it to anyone. We 2039 * will not restart on SIGHUP since it no longer makes sense. 2040 */ 2041 alarm(0); 2042 signal(SIGALRM, SIG_DFL); 2043 signal(SIGHUP, SIG_DFL); 2044 signal(SIGTERM, SIG_DFL); 2045 signal(SIGQUIT, SIG_DFL); 2046 signal(SIGCHLD, SIG_DFL); 2047 signal(SIGINT, SIG_DFL); 2048 2049 /* 2050 * Register our connection. This turns encryption off because we do 2051 * not have a key. 2052 */ 2053 packet_set_connection(sock_in, sock_out); 2054 packet_set_server(); 2055 2056 /* Set SO_KEEPALIVE if requested. */ 2057 if (options.tcp_keep_alive && packet_connection_is_on_socket() && 2058 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) 2059 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2060 2061 if ((remote_port = get_remote_port()) < 0) { 2062 debug("get_remote_port failed"); 2063 cleanup_exit(255); 2064 } 2065 2066 /* 2067 * We use get_canonical_hostname with usedns = 0 instead of 2068 * get_remote_ipaddr here so IP options will be checked. 2069 */ 2070 (void) get_canonical_hostname(0); 2071 /* 2072 * The rest of the code depends on the fact that 2073 * get_remote_ipaddr() caches the remote ip, even if 2074 * the socket goes away. 2075 */ 2076 remote_ip = get_remote_ipaddr(); 2077 2078 #ifdef SSH_AUDIT_EVENTS 2079 audit_connection_from(remote_ip, remote_port); 2080 #endif 2081 2082 /* Log the connection. */ 2083 verbose("Connection from %s port %d on %s port %d", 2084 remote_ip, remote_port, 2085 get_local_ipaddr(sock_in), get_local_port()); 2086 2087 /* set the HPN options for the child */ 2088 channel_set_hpn(options.hpn_disabled, options.hpn_buffer_size); 2089 2090 /* 2091 * We don't want to listen forever unless the other side 2092 * successfully authenticates itself. So we set up an alarm which is 2093 * cleared after successful authentication. A limit of zero 2094 * indicates no limit. Note that we don't set the alarm in debugging 2095 * mode; it is just annoying to have the server exit just when you 2096 * are about to discover the bug. 2097 */ 2098 signal(SIGALRM, grace_alarm_handler); 2099 if (!debug_flag) 2100 alarm(options.login_grace_time); 2101 2102 sshd_exchange_identification(sock_in, sock_out); 2103 2104 /* In inetd mode, generate ephemeral key only for proto 1 connections */ 2105 if (!compat20 && inetd_flag && sensitive_data.server_key == NULL) 2106 generate_ephemeral_server_key(); 2107 2108 packet_set_nonblocking(); 2109 2110 /* allocate authentication context */ 2111 authctxt = xcalloc(1, sizeof(*authctxt)); 2112 2113 authctxt->loginmsg = &loginmsg; 2114 2115 /* XXX global for cleanup, access from other modules */ 2116 the_authctxt = authctxt; 2117 2118 /* prepare buffer to collect messages to display to user after login */ 2119 buffer_init(&loginmsg); 2120 auth_debug_reset(); 2121 2122 if (use_privsep) { 2123 if (privsep_preauth(authctxt) == 1) 2124 goto authenticated; 2125 } else if (compat20 && have_agent) 2126 auth_conn = ssh_get_authentication_connection(); 2127 2128 /* perform the key exchange */ 2129 /* authenticate user and start session */ 2130 if (compat20) { 2131 do_ssh2_kex(); 2132 do_authentication2(authctxt); 2133 } else { 2134 #ifdef WITH_SSH1 2135 do_ssh1_kex(); 2136 do_authentication(authctxt); 2137 #else 2138 fatal("ssh1 not supported"); 2139 #endif 2140 } 2141 /* 2142 * If we use privilege separation, the unprivileged child transfers 2143 * the current keystate and exits 2144 */ 2145 if (use_privsep) { 2146 mm_send_keystate(pmonitor); 2147 exit(0); 2148 } 2149 2150 authenticated: 2151 /* 2152 * Cancel the alarm we set to limit the time taken for 2153 * authentication. 2154 */ 2155 alarm(0); 2156 signal(SIGALRM, SIG_DFL); 2157 authctxt->authenticated = 1; 2158 if (startup_pipe != -1) { 2159 close(startup_pipe); 2160 startup_pipe = -1; 2161 } 2162 2163 #ifdef SSH_AUDIT_EVENTS 2164 audit_event(SSH_AUTH_SUCCESS); 2165 #endif 2166 2167 #ifdef GSSAPI 2168 if (options.gss_authentication) { 2169 temporarily_use_uid(authctxt->pw); 2170 ssh_gssapi_storecreds(); 2171 restore_uid(); 2172 } 2173 #endif 2174 #ifdef USE_PAM 2175 if (options.use_pam) { 2176 do_pam_setcred(1); 2177 do_pam_session(); 2178 } 2179 #endif 2180 2181 /* 2182 * In privilege separation, we fork another child and prepare 2183 * file descriptor passing. 2184 */ 2185 if (use_privsep) { 2186 privsep_postauth(authctxt); 2187 /* the monitor process [priv] will not return */ 2188 if (!compat20) 2189 destroy_sensitive_data(); 2190 } 2191 2192 packet_set_timeout(options.client_alive_interval, 2193 options.client_alive_count_max); 2194 2195 /* Start session. */ 2196 2197 /* if we are using aes-ctr there can be issues in either a fork or sandbox 2198 * so the initial aes-ctr is defined to point ot the original single process 2199 * evp. After authentication we'll be past the fork and the sandboxed privsep 2200 * so we repoint the define to the multithreaded evp. To start the threads we 2201 * then force a rekey 2202 */ 2203 CipherContext *ccsend; 2204 ccsend = (CipherContext*)packet_get_send_context(); 2205 2206 /* only rekey if necessary. If we don't do this gcm mode cipher breaks */ 2207 if (strstr(cipher_return_name((Cipher*)ccsend->cipher), "ctr")) { 2208 debug ("Single to Multithreaded CTR cipher swap - server request"); 2209 cipher_reset_multithreaded(); 2210 packet_request_rekeying(); 2211 } 2212 2213 do_authenticated(authctxt); 2214 2215 /* The connection has been terminated. */ 2216 packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes); 2217 packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes); 2218 verbose("Transferred: sent %llu, received %llu bytes", 2219 (unsigned long long)obytes, (unsigned long long)ibytes); 2220 2221 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2222 2223 #ifdef USE_PAM 2224 if (options.use_pam) 2225 finish_pam(); 2226 #endif /* USE_PAM */ 2227 2228 #ifdef SSH_AUDIT_EVENTS 2229 PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); 2230 #endif 2231 2232 packet_close(); 2233 2234 if (use_privsep) 2235 mm_terminate(); 2236 2237 exit(0); 2238 } 2239 2240 #ifdef WITH_SSH1 2241 /* 2242 * Decrypt session_key_int using our private server key and private host key 2243 * (key with larger modulus first). 2244 */ 2245 int 2246 ssh1_session_key(BIGNUM *session_key_int) 2247 { 2248 int rsafail = 0; 2249 2250 if (BN_cmp(sensitive_data.server_key->rsa->n, 2251 sensitive_data.ssh1_host_key->rsa->n) > 0) { 2252 /* Server key has bigger modulus. */ 2253 if (BN_num_bits(sensitive_data.server_key->rsa->n) < 2254 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + 2255 SSH_KEY_BITS_RESERVED) { 2256 fatal("do_connection: %s: " 2257 "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", 2258 get_remote_ipaddr(), 2259 BN_num_bits(sensitive_data.server_key->rsa->n), 2260 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2261 SSH_KEY_BITS_RESERVED); 2262 } 2263 if (rsa_private_decrypt(session_key_int, session_key_int, 2264 sensitive_data.server_key->rsa) != 0) 2265 rsafail++; 2266 if (rsa_private_decrypt(session_key_int, session_key_int, 2267 sensitive_data.ssh1_host_key->rsa) != 0) 2268 rsafail++; 2269 } else { 2270 /* Host key has bigger modulus (or they are equal). */ 2271 if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < 2272 BN_num_bits(sensitive_data.server_key->rsa->n) + 2273 SSH_KEY_BITS_RESERVED) { 2274 fatal("do_connection: %s: " 2275 "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", 2276 get_remote_ipaddr(), 2277 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), 2278 BN_num_bits(sensitive_data.server_key->rsa->n), 2279 SSH_KEY_BITS_RESERVED); 2280 } 2281 if (rsa_private_decrypt(session_key_int, session_key_int, 2282 sensitive_data.ssh1_host_key->rsa) != 0) 2283 rsafail++; 2284 if (rsa_private_decrypt(session_key_int, session_key_int, 2285 sensitive_data.server_key->rsa) != 0) 2286 rsafail++; 2287 } 2288 return (rsafail); 2289 } 2290 2291 /* 2292 * SSH1 key exchange 2293 */ 2294 static void 2295 do_ssh1_kex(void) 2296 { 2297 int i, len; 2298 int rsafail = 0; 2299 BIGNUM *session_key_int; 2300 u_char session_key[SSH_SESSION_KEY_LENGTH]; 2301 u_char cookie[8]; 2302 u_int cipher_type, auth_mask, protocol_flags; 2303 2304 /* 2305 * Generate check bytes that the client must send back in the user 2306 * packet in order for it to be accepted; this is used to defy ip 2307 * spoofing attacks. Note that this only works against somebody 2308 * doing IP spoofing from a remote machine; any machine on the local 2309 * network can still see outgoing packets and catch the random 2310 * cookie. This only affects rhosts authentication, and this is one 2311 * of the reasons why it is inherently insecure. 2312 */ 2313 arc4random_buf(cookie, sizeof(cookie)); 2314 2315 /* 2316 * Send our public key. We include in the packet 64 bits of random 2317 * data that must be matched in the reply in order to prevent IP 2318 * spoofing. 2319 */ 2320 packet_start(SSH_SMSG_PUBLIC_KEY); 2321 for (i = 0; i < 8; i++) 2322 packet_put_char(cookie[i]); 2323 2324 /* Store our public server RSA key. */ 2325 packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); 2326 packet_put_bignum(sensitive_data.server_key->rsa->e); 2327 packet_put_bignum(sensitive_data.server_key->rsa->n); 2328 2329 /* Store our public host RSA key. */ 2330 packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2331 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); 2332 packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); 2333 2334 /* Put protocol flags. */ 2335 packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); 2336 2337 /* Declare which ciphers we support. */ 2338 packet_put_int(cipher_mask_ssh1(0)); 2339 2340 /* Declare supported authentication types. */ 2341 auth_mask = 0; 2342 if (options.rhosts_rsa_authentication) 2343 auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; 2344 if (options.rsa_authentication) 2345 auth_mask |= 1 << SSH_AUTH_RSA; 2346 if (options.challenge_response_authentication == 1) 2347 auth_mask |= 1 << SSH_AUTH_TIS; 2348 if (options.password_authentication) 2349 auth_mask |= 1 << SSH_AUTH_PASSWORD; 2350 packet_put_int(auth_mask); 2351 2352 /* Send the packet and wait for it to be sent. */ 2353 packet_send(); 2354 packet_write_wait(); 2355 2356 debug("Sent %d bit server key and %d bit host key.", 2357 BN_num_bits(sensitive_data.server_key->rsa->n), 2358 BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); 2359 2360 /* Read clients reply (cipher type and session key). */ 2361 packet_read_expect(SSH_CMSG_SESSION_KEY); 2362 2363 /* Get cipher type and check whether we accept this. */ 2364 cipher_type = packet_get_char(); 2365 2366 if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) 2367 packet_disconnect("Warning: client selects unsupported cipher."); 2368 2369 /* Get check bytes from the packet. These must match those we 2370 sent earlier with the public key packet. */ 2371 for (i = 0; i < 8; i++) 2372 if (cookie[i] != packet_get_char()) 2373 packet_disconnect("IP Spoofing check bytes do not match."); 2374 2375 debug("Encryption type: %.200s", cipher_name(cipher_type)); 2376 2377 /* Get the encrypted integer. */ 2378 if ((session_key_int = BN_new()) == NULL) 2379 fatal("do_ssh1_kex: BN_new failed"); 2380 packet_get_bignum(session_key_int); 2381 2382 protocol_flags = packet_get_int(); 2383 packet_set_protocol_flags(protocol_flags); 2384 packet_check_eom(); 2385 2386 /* Decrypt session_key_int using host/server keys */ 2387 rsafail = PRIVSEP(ssh1_session_key(session_key_int)); 2388 2389 /* 2390 * Extract session key from the decrypted integer. The key is in the 2391 * least significant 256 bits of the integer; the first byte of the 2392 * key is in the highest bits. 2393 */ 2394 if (!rsafail) { 2395 (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); 2396 len = BN_num_bytes(session_key_int); 2397 if (len < 0 || (u_int)len > sizeof(session_key)) { 2398 error("do_ssh1_kex: bad session key len from %s: " 2399 "session_key_int %d > sizeof(session_key) %lu", 2400 get_remote_ipaddr(), len, (u_long)sizeof(session_key)); 2401 rsafail++; 2402 } else { 2403 explicit_bzero(session_key, sizeof(session_key)); 2404 BN_bn2bin(session_key_int, 2405 session_key + sizeof(session_key) - len); 2406 2407 derive_ssh1_session_id( 2408 sensitive_data.ssh1_host_key->rsa->n, 2409 sensitive_data.server_key->rsa->n, 2410 cookie, session_id); 2411 /* 2412 * Xor the first 16 bytes of the session key with the 2413 * session id. 2414 */ 2415 for (i = 0; i < 16; i++) 2416 session_key[i] ^= session_id[i]; 2417 } 2418 } 2419 if (rsafail) { 2420 int bytes = BN_num_bytes(session_key_int); 2421 u_char *buf = xmalloc(bytes); 2422 struct ssh_digest_ctx *md; 2423 2424 logit("do_connection: generating a fake encryption key"); 2425 BN_bn2bin(session_key_int, buf); 2426 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || 2427 ssh_digest_update(md, buf, bytes) < 0 || 2428 ssh_digest_update(md, sensitive_data.ssh1_cookie, 2429 SSH_SESSION_KEY_LENGTH) < 0 || 2430 ssh_digest_final(md, session_key, sizeof(session_key)) < 0) 2431 fatal("%s: md5 failed", __func__); 2432 ssh_digest_free(md); 2433 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL || 2434 ssh_digest_update(md, session_key, 16) < 0 || 2435 ssh_digest_update(md, sensitive_data.ssh1_cookie, 2436 SSH_SESSION_KEY_LENGTH) < 0 || 2437 ssh_digest_final(md, session_key + 16, 2438 sizeof(session_key) - 16) < 0) 2439 fatal("%s: md5 failed", __func__); 2440 ssh_digest_free(md); 2441 explicit_bzero(buf, bytes); 2442 free(buf); 2443 for (i = 0; i < 16; i++) 2444 session_id[i] = session_key[i] ^ session_key[i + 16]; 2445 } 2446 /* Destroy the private and public keys. No longer. */ 2447 destroy_sensitive_data(); 2448 2449 if (use_privsep) 2450 mm_ssh1_session_id(session_id); 2451 2452 /* Destroy the decrypted integer. It is no longer needed. */ 2453 BN_clear_free(session_key_int); 2454 2455 /* Set the session key. From this on all communications will be encrypted. */ 2456 packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); 2457 2458 /* Destroy our copy of the session key. It is no longer needed. */ 2459 explicit_bzero(session_key, sizeof(session_key)); 2460 2461 debug("Received session key; encryption turned on."); 2462 2463 /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ 2464 packet_start(SSH_SMSG_SUCCESS); 2465 packet_send(); 2466 packet_write_wait(); 2467 } 2468 #endif 2469 2470 void 2471 sshd_hostkey_sign(Key *privkey, Key *pubkey, u_char **signature, u_int *slen, 2472 u_char *data, u_int dlen) 2473 { 2474 if (privkey) { 2475 if (PRIVSEP(key_sign(privkey, signature, slen, data, dlen) < 0)) 2476 fatal("%s: key_sign failed", __func__); 2477 } else if (use_privsep) { 2478 if (mm_key_sign(pubkey, signature, slen, data, dlen) < 0) 2479 fatal("%s: pubkey_sign failed", __func__); 2480 } else { 2481 if (ssh_agent_sign(auth_conn, pubkey, signature, slen, data, 2482 dlen)) 2483 fatal("%s: ssh_agent_sign failed", __func__); 2484 } 2485 } 2486 2487 /* 2488 * SSH2 key exchange: diffie-hellman-group1-sha1 2489 */ 2490 static void 2491 do_ssh2_kex(void) 2492 { 2493 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2494 Kex *kex; 2495 2496 myflag++; 2497 debug ("MYFLAG IS %d", myflag); 2498 if (options.ciphers != NULL) { 2499 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2500 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; 2501 } else if (options.none_enabled == 1) { 2502 debug ("WARNING: None cipher enabled"); 2503 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2504 myproposal[PROPOSAL_ENC_ALGS_STOC] = KEX_ENCRYPT_INCLUDE_NONE; 2505 } 2506 myproposal[PROPOSAL_ENC_ALGS_CTOS] = 2507 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); 2508 myproposal[PROPOSAL_ENC_ALGS_STOC] = 2509 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); 2510 2511 if (options.macs != NULL) { 2512 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2513 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2514 } 2515 if (options.compression == COMP_NONE) { 2516 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2517 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2518 } else if (options.compression == COMP_DELAYED) { 2519 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2520 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; 2521 } 2522 if (options.kex_algorithms != NULL) 2523 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms; 2524 2525 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2526 myproposal[PROPOSAL_KEX_ALGS]); 2527 2528 if (options.rekey_limit || options.rekey_interval) 2529 packet_set_rekey_limits((u_int32_t)options.rekey_limit, 2530 (time_t)options.rekey_interval); 2531 2532 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2533 list_hostkey_types()); 2534 2535 /* start key exchange */ 2536 kex = kex_setup(myproposal); 2537 #ifdef WITH_OPENSSL 2538 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 2539 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 2540 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2541 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2542 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 2543 #endif 2544 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 2545 kex->server = 1; 2546 kex->client_version_string=client_version_string; 2547 kex->server_version_string=server_version_string; 2548 kex->load_host_public_key=&get_hostkey_public_by_type; 2549 kex->load_host_private_key=&get_hostkey_private_by_type; 2550 kex->host_key_index=&get_hostkey_index; 2551 kex->sign = sshd_hostkey_sign; 2552 2553 xxx_kex = kex; 2554 2555 dispatch_run(DISPATCH_BLOCK, &kex->done, kex); 2556 2557 session_id2 = kex->session_id; 2558 session_id2_len = kex->session_id_len; 2559 2560 #ifdef DEBUG_KEXDH 2561 /* send 1st encrypted/maced/compressed message */ 2562 packet_start(SSH2_MSG_IGNORE); 2563 packet_put_cstring("markus"); 2564 packet_send(); 2565 packet_write_wait(); 2566 #endif 2567 debug("KEX done"); 2568 } 2569 2570 /* server specific fatal cleanup */ 2571 void 2572 cleanup_exit(int i) 2573 { 2574 if (the_authctxt) { 2575 do_cleanup(the_authctxt); 2576 if (use_privsep && privsep_is_preauth && 2577 pmonitor != NULL && pmonitor->m_pid > 1) { 2578 debug("Killing privsep child %d", pmonitor->m_pid); 2579 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2580 errno != ESRCH) 2581 error("%s: kill(%d): %s", __func__, 2582 pmonitor->m_pid, strerror(errno)); 2583 } 2584 } 2585 #ifdef SSH_AUDIT_EVENTS 2586 /* done after do_cleanup so it can cancel the PAM auth 'thread' */ 2587 if (!use_privsep || mm_is_monitor()) 2588 audit_event(SSH_CONNECTION_ABANDON); 2589 #endif 2590 _exit(i); 2591 } 2592