1 /* $OpenBSD: sshd.c,v 1.560 2020/07/03 10:12:26 markus 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 <sys/types.h> 46 #include <sys/ioctl.h> 47 #include <sys/wait.h> 48 #include <sys/tree.h> 49 #include <sys/stat.h> 50 #include <sys/socket.h> 51 #include <sys/time.h> 52 #include <sys/queue.h> 53 54 #include <errno.h> 55 #include <fcntl.h> 56 #include <netdb.h> 57 #include <paths.h> 58 #include <pwd.h> 59 #include <signal.h> 60 #include <stdio.h> 61 #include <stdlib.h> 62 #include <string.h> 63 #include <stdarg.h> 64 #include <unistd.h> 65 #include <limits.h> 66 67 #ifdef WITH_OPENSSL 68 #include <openssl/bn.h> 69 #endif 70 71 #include "xmalloc.h" 72 #include "ssh.h" 73 #include "ssh2.h" 74 #include "sshpty.h" 75 #include "packet.h" 76 #include "log.h" 77 #include "sshbuf.h" 78 #include "misc.h" 79 #include "match.h" 80 #include "servconf.h" 81 #include "uidswap.h" 82 #include "compat.h" 83 #include "cipher.h" 84 #include "digest.h" 85 #include "sshkey.h" 86 #include "kex.h" 87 #include "myproposal.h" 88 #include "authfile.h" 89 #include "pathnames.h" 90 #include "atomicio.h" 91 #include "canohost.h" 92 #include "hostfile.h" 93 #include "auth.h" 94 #include "authfd.h" 95 #include "msg.h" 96 #include "dispatch.h" 97 #include "channels.h" 98 #include "session.h" 99 #include "monitor.h" 100 #ifdef GSSAPI 101 #include "ssh-gss.h" 102 #endif 103 #include "monitor_wrap.h" 104 #include "ssh-sandbox.h" 105 #include "auth-options.h" 106 #include "version.h" 107 #include "ssherr.h" 108 #include "sk-api.h" 109 110 /* Re-exec fds */ 111 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 112 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 113 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 114 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 115 116 extern char *__progname; 117 118 /* Server configuration options. */ 119 ServerOptions options; 120 121 /* Name of the server configuration file. */ 122 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 123 124 /* 125 * Debug mode flag. This can be set on the command line. If debug 126 * mode is enabled, extra debugging output will be sent to the system 127 * log, the daemon will not go to background, and will exit after processing 128 * the first connection. 129 */ 130 int debug_flag = 0; 131 132 /* 133 * Indicating that the daemon should only test the configuration and keys. 134 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 135 * configuration, optionally using connection information provided by the 136 * "-C" flag. 137 */ 138 static int test_flag = 0; 139 140 /* Flag indicating that the daemon is being started from inetd. */ 141 static int inetd_flag = 0; 142 143 /* Flag indicating that sshd should not detach and become a daemon. */ 144 static int no_daemon_flag = 0; 145 146 /* debug goes to stderr unless inetd_flag is set */ 147 static int log_stderr = 0; 148 149 /* Saved arguments to main(). */ 150 static char **saved_argv; 151 152 /* re-exec */ 153 static int rexeced_flag = 0; 154 static int rexec_flag = 1; 155 static int rexec_argc = 0; 156 static char **rexec_argv; 157 158 /* 159 * The sockets that the server is listening; this is used in the SIGHUP 160 * signal handler. 161 */ 162 #define MAX_LISTEN_SOCKS 16 163 static int listen_socks[MAX_LISTEN_SOCKS]; 164 static int num_listen_socks = 0; 165 166 /* Daemon's agent connection */ 167 int auth_sock = -1; 168 static int have_agent = 0; 169 170 /* 171 * Any really sensitive data in the application is contained in this 172 * structure. The idea is that this structure could be locked into memory so 173 * that the pages do not get written into swap. However, there are some 174 * problems. The private key contains BIGNUMs, and we do not (in principle) 175 * have access to the internals of them, and locking just the structure is 176 * not very useful. Currently, memory locking is not implemented. 177 */ 178 struct { 179 struct sshkey **host_keys; /* all private host keys */ 180 struct sshkey **host_pubkeys; /* all public host keys */ 181 struct sshkey **host_certificates; /* all public host certificates */ 182 int have_ssh2_key; 183 } sensitive_data; 184 185 /* This is set to true when a signal is received. */ 186 static volatile sig_atomic_t received_sighup = 0; 187 static volatile sig_atomic_t received_sigterm = 0; 188 189 /* session identifier, used by RSA-auth */ 190 u_char session_id[16]; 191 192 /* same for ssh2 */ 193 u_char *session_id2 = NULL; 194 u_int session_id2_len = 0; 195 196 /* record remote hostname or ip */ 197 u_int utmp_len = HOST_NAME_MAX+1; 198 199 /* 200 * startup_pipes/flags are used for tracking children of the listening sshd 201 * process early in their lifespans. This tracking is needed for three things: 202 * 203 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 204 * connections. 205 * 2) Avoiding a race condition for SIGHUP processing, where child processes 206 * may have listen_socks open that could collide with main listener process 207 * after it restarts. 208 * 3) Ensuring that rexec'd sshd processes have received their initial state 209 * from the parent listen process before handling SIGHUP. 210 * 211 * Child processes signal that they have completed closure of the listen_socks 212 * and (if applicable) received their rexec state by sending a char over their 213 * sock. Child processes signal that authentication has completed by closing 214 * the sock (or by exiting). 215 */ 216 static int *startup_pipes = NULL; 217 static int *startup_flags = NULL; /* Indicates child closed listener */ 218 static int startup_pipe = -1; /* in child */ 219 220 /* variables used for privilege separation */ 221 int use_privsep = -1; 222 struct monitor *pmonitor = NULL; 223 int privsep_is_preauth = 1; 224 225 /* global connection state and authentication contexts */ 226 Authctxt *the_authctxt = NULL; 227 struct ssh *the_active_state; 228 229 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 230 struct sshauthopt *auth_opts = NULL; 231 232 /* sshd_config buffer */ 233 struct sshbuf *cfg; 234 235 /* Included files from the configuration file */ 236 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 237 238 /* message to be displayed after login */ 239 struct sshbuf *loginmsg; 240 241 /* Prototypes for various functions defined later in this file. */ 242 void destroy_sensitive_data(void); 243 void demote_sensitive_data(void); 244 static void do_ssh2_kex(struct ssh *); 245 246 static char *listener_proctitle; 247 248 /* 249 * Close all listening sockets 250 */ 251 static void 252 close_listen_socks(void) 253 { 254 int i; 255 256 for (i = 0; i < num_listen_socks; i++) 257 close(listen_socks[i]); 258 num_listen_socks = -1; 259 } 260 261 static void 262 close_startup_pipes(void) 263 { 264 int i; 265 266 if (startup_pipes) 267 for (i = 0; i < options.max_startups; i++) 268 if (startup_pipes[i] != -1) 269 close(startup_pipes[i]); 270 } 271 272 /* 273 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 274 * the effect is to reread the configuration file (and to regenerate 275 * the server key). 276 */ 277 278 /*ARGSUSED*/ 279 static void 280 sighup_handler(int sig) 281 { 282 received_sighup = 1; 283 } 284 285 /* 286 * Called from the main program after receiving SIGHUP. 287 * Restarts the server. 288 */ 289 static void 290 sighup_restart(void) 291 { 292 logit("Received SIGHUP; restarting."); 293 if (options.pid_file != NULL) 294 unlink(options.pid_file); 295 close_listen_socks(); 296 close_startup_pipes(); 297 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 298 execv(saved_argv[0], saved_argv); 299 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 300 strerror(errno)); 301 exit(1); 302 } 303 304 /* 305 * Generic signal handler for terminating signals in the master daemon. 306 */ 307 /*ARGSUSED*/ 308 static void 309 sigterm_handler(int sig) 310 { 311 received_sigterm = sig; 312 } 313 314 /* 315 * SIGCHLD handler. This is called whenever a child dies. This will then 316 * reap any zombies left by exited children. 317 */ 318 /*ARGSUSED*/ 319 static void 320 main_sigchld_handler(int sig) 321 { 322 int save_errno = errno; 323 pid_t pid; 324 int status; 325 326 debug("main_sigchld_handler: %s", strsignal(sig)); 327 328 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 329 (pid == -1 && errno == EINTR)) 330 ; 331 errno = save_errno; 332 } 333 334 /* 335 * Signal handler for the alarm after the login grace period has expired. 336 */ 337 /*ARGSUSED*/ 338 static void 339 grace_alarm_handler(int sig) 340 { 341 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 342 kill(pmonitor->m_pid, SIGALRM); 343 344 /* 345 * Try to kill any processes that we have spawned, E.g. authorized 346 * keys command helpers. 347 */ 348 if (getpgid(0) == getpid()) { 349 ssh_signal(SIGTERM, SIG_IGN); 350 kill(0, SIGTERM); 351 } 352 353 /* XXX pre-format ipaddr/port so we don't need to access active_state */ 354 /* Log error and exit. */ 355 sigdie("Timeout before authentication for %s port %d", 356 ssh_remote_ipaddr(the_active_state), 357 ssh_remote_port(the_active_state)); 358 } 359 360 /* Destroy the host and server keys. They will no longer be needed. */ 361 void 362 destroy_sensitive_data(void) 363 { 364 u_int i; 365 366 for (i = 0; i < options.num_host_key_files; i++) { 367 if (sensitive_data.host_keys[i]) { 368 sshkey_free(sensitive_data.host_keys[i]); 369 sensitive_data.host_keys[i] = NULL; 370 } 371 if (sensitive_data.host_certificates[i]) { 372 sshkey_free(sensitive_data.host_certificates[i]); 373 sensitive_data.host_certificates[i] = NULL; 374 } 375 } 376 } 377 378 /* Demote private to public keys for network child */ 379 void 380 demote_sensitive_data(void) 381 { 382 struct sshkey *tmp; 383 u_int i; 384 int r; 385 386 for (i = 0; i < options.num_host_key_files; i++) { 387 if (sensitive_data.host_keys[i]) { 388 if ((r = sshkey_from_private( 389 sensitive_data.host_keys[i], &tmp)) != 0) 390 fatal("could not demote host %s key: %s", 391 sshkey_type(sensitive_data.host_keys[i]), 392 ssh_err(r)); 393 sshkey_free(sensitive_data.host_keys[i]); 394 sensitive_data.host_keys[i] = tmp; 395 } 396 /* Certs do not need demotion */ 397 } 398 } 399 400 static void 401 privsep_preauth_child(void) 402 { 403 gid_t gidset[1]; 404 struct passwd *pw; 405 406 /* Enable challenge-response authentication for privilege separation */ 407 privsep_challenge_enable(); 408 409 #ifdef GSSAPI 410 /* Cache supported mechanism OIDs for later use */ 411 ssh_gssapi_prepare_supported_oids(); 412 #endif 413 414 /* Demote the private keys to public keys. */ 415 demote_sensitive_data(); 416 417 /* Demote the child */ 418 if (getuid() == 0 || geteuid() == 0) { 419 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) 420 fatal("Privilege separation user %s does not exist", 421 SSH_PRIVSEP_USER); 422 pw = pwcopy(pw); /* Ensure mutable */ 423 endpwent(); 424 freezero(pw->pw_passwd, strlen(pw->pw_passwd)); 425 426 /* Change our root directory */ 427 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 428 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 429 strerror(errno)); 430 if (chdir("/") == -1) 431 fatal("chdir(\"/\"): %s", strerror(errno)); 432 433 /* 434 * Drop our privileges 435 * NB. Can't use setusercontext() after chroot. 436 */ 437 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, 438 (u_int)pw->pw_gid); 439 gidset[0] = pw->pw_gid; 440 if (setgroups(1, gidset) == -1) 441 fatal("setgroups: %.100s", strerror(errno)); 442 permanently_set_uid(pw); 443 } 444 } 445 446 static int 447 privsep_preauth(struct ssh *ssh) 448 { 449 int status, r; 450 pid_t pid; 451 struct ssh_sandbox *box = NULL; 452 453 /* Set up unprivileged child process to deal with network data */ 454 pmonitor = monitor_init(); 455 /* Store a pointer to the kex for later rekeying */ 456 pmonitor->m_pkex = &ssh->kex; 457 458 if (use_privsep == PRIVSEP_ON) 459 box = ssh_sandbox_init(); 460 pid = fork(); 461 if (pid == -1) { 462 fatal("fork of unprivileged child failed"); 463 } else if (pid != 0) { 464 debug2("Network child is on pid %ld", (long)pid); 465 466 pmonitor->m_pid = pid; 467 if (have_agent) { 468 r = ssh_get_authentication_socket(&auth_sock); 469 if (r != 0) { 470 error("Could not get agent socket: %s", 471 ssh_err(r)); 472 have_agent = 0; 473 } 474 } 475 if (box != NULL) 476 ssh_sandbox_parent_preauth(box, pid); 477 monitor_child_preauth(ssh, pmonitor); 478 479 /* Wait for the child's exit status */ 480 while (waitpid(pid, &status, 0) == -1) { 481 if (errno == EINTR) 482 continue; 483 pmonitor->m_pid = -1; 484 fatal("%s: waitpid: %s", __func__, strerror(errno)); 485 } 486 privsep_is_preauth = 0; 487 pmonitor->m_pid = -1; 488 if (WIFEXITED(status)) { 489 if (WEXITSTATUS(status) != 0) 490 fatal("%s: preauth child exited with status %d", 491 __func__, WEXITSTATUS(status)); 492 } else if (WIFSIGNALED(status)) 493 fatal("%s: preauth child terminated by signal %d", 494 __func__, WTERMSIG(status)); 495 if (box != NULL) 496 ssh_sandbox_parent_finish(box); 497 return 1; 498 } else { 499 /* child */ 500 close(pmonitor->m_sendfd); 501 close(pmonitor->m_log_recvfd); 502 503 /* Arrange for logging to be sent to the monitor */ 504 set_log_handler(mm_log_handler, pmonitor); 505 506 privsep_preauth_child(); 507 setproctitle("%s", "[net]"); 508 if (box != NULL) 509 ssh_sandbox_child(box); 510 511 return 0; 512 } 513 } 514 515 static void 516 privsep_postauth(struct ssh *ssh, Authctxt *authctxt) 517 { 518 if (authctxt->pw->pw_uid == 0) { 519 /* File descriptor passing is broken or root login */ 520 use_privsep = 0; 521 goto skip; 522 } 523 524 /* New socket pair */ 525 monitor_reinit(pmonitor); 526 527 pmonitor->m_pid = fork(); 528 if (pmonitor->m_pid == -1) 529 fatal("fork of unprivileged child failed"); 530 else if (pmonitor->m_pid != 0) { 531 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 532 sshbuf_reset(loginmsg); 533 monitor_clear_keystate(ssh, pmonitor); 534 monitor_child_postauth(ssh, pmonitor); 535 536 /* NEVERREACHED */ 537 exit(0); 538 } 539 540 /* child */ 541 542 close(pmonitor->m_sendfd); 543 pmonitor->m_sendfd = -1; 544 545 /* Demote the private keys to public keys. */ 546 demote_sensitive_data(); 547 548 /* Drop privileges */ 549 do_setusercontext(authctxt->pw); 550 551 skip: 552 /* It is safe now to apply the key state */ 553 monitor_apply_keystate(ssh, pmonitor); 554 555 /* 556 * Tell the packet layer that authentication was successful, since 557 * this information is not part of the key state. 558 */ 559 ssh_packet_set_authenticated(ssh); 560 } 561 562 static void 563 append_hostkey_type(struct sshbuf *b, const char *s) 564 { 565 int r; 566 567 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 568 debug3("%s: %s key not permitted by HostkeyAlgorithms", 569 __func__, s); 570 return; 571 } 572 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 573 fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r)); 574 } 575 576 static char * 577 list_hostkey_types(void) 578 { 579 struct sshbuf *b; 580 struct sshkey *key; 581 char *ret; 582 u_int i; 583 584 if ((b = sshbuf_new()) == NULL) 585 fatal("%s: sshbuf_new failed", __func__); 586 for (i = 0; i < options.num_host_key_files; i++) { 587 key = sensitive_data.host_keys[i]; 588 if (key == NULL) 589 key = sensitive_data.host_pubkeys[i]; 590 if (key == NULL) 591 continue; 592 switch (key->type) { 593 case KEY_RSA: 594 /* for RSA we also support SHA2 signatures */ 595 append_hostkey_type(b, "rsa-sha2-512"); 596 append_hostkey_type(b, "rsa-sha2-256"); 597 /* FALLTHROUGH */ 598 case KEY_DSA: 599 case KEY_ECDSA: 600 case KEY_ED25519: 601 case KEY_ECDSA_SK: 602 case KEY_ED25519_SK: 603 case KEY_XMSS: 604 append_hostkey_type(b, sshkey_ssh_name(key)); 605 break; 606 } 607 /* If the private key has a cert peer, then list that too */ 608 key = sensitive_data.host_certificates[i]; 609 if (key == NULL) 610 continue; 611 switch (key->type) { 612 case KEY_RSA_CERT: 613 /* for RSA we also support SHA2 signatures */ 614 append_hostkey_type(b, 615 "rsa-sha2-512-cert-v01@openssh.com"); 616 append_hostkey_type(b, 617 "rsa-sha2-256-cert-v01@openssh.com"); 618 /* FALLTHROUGH */ 619 case KEY_DSA_CERT: 620 case KEY_ECDSA_CERT: 621 case KEY_ED25519_CERT: 622 case KEY_ECDSA_SK_CERT: 623 case KEY_ED25519_SK_CERT: 624 case KEY_XMSS_CERT: 625 append_hostkey_type(b, sshkey_ssh_name(key)); 626 break; 627 } 628 } 629 if ((ret = sshbuf_dup_string(b)) == NULL) 630 fatal("%s: sshbuf_dup_string failed", __func__); 631 sshbuf_free(b); 632 debug("%s: %s", __func__, ret); 633 return ret; 634 } 635 636 static struct sshkey * 637 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 638 { 639 u_int i; 640 struct sshkey *key; 641 642 for (i = 0; i < options.num_host_key_files; i++) { 643 switch (type) { 644 case KEY_RSA_CERT: 645 case KEY_DSA_CERT: 646 case KEY_ECDSA_CERT: 647 case KEY_ED25519_CERT: 648 case KEY_ECDSA_SK_CERT: 649 case KEY_ED25519_SK_CERT: 650 case KEY_XMSS_CERT: 651 key = sensitive_data.host_certificates[i]; 652 break; 653 default: 654 key = sensitive_data.host_keys[i]; 655 if (key == NULL && !need_private) 656 key = sensitive_data.host_pubkeys[i]; 657 break; 658 } 659 if (key == NULL || key->type != type) 660 continue; 661 switch (type) { 662 case KEY_ECDSA: 663 case KEY_ECDSA_SK: 664 case KEY_ECDSA_CERT: 665 case KEY_ECDSA_SK_CERT: 666 if (key->ecdsa_nid != nid) 667 continue; 668 /* FALLTHROUGH */ 669 default: 670 return need_private ? 671 sensitive_data.host_keys[i] : key; 672 } 673 } 674 return NULL; 675 } 676 677 struct sshkey * 678 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 679 { 680 return get_hostkey_by_type(type, nid, 0, ssh); 681 } 682 683 struct sshkey * 684 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 685 { 686 return get_hostkey_by_type(type, nid, 1, ssh); 687 } 688 689 struct sshkey * 690 get_hostkey_by_index(int ind) 691 { 692 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 693 return (NULL); 694 return (sensitive_data.host_keys[ind]); 695 } 696 697 struct sshkey * 698 get_hostkey_public_by_index(int ind, struct ssh *ssh) 699 { 700 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 701 return (NULL); 702 return (sensitive_data.host_pubkeys[ind]); 703 } 704 705 int 706 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 707 { 708 u_int i; 709 710 for (i = 0; i < options.num_host_key_files; i++) { 711 if (sshkey_is_cert(key)) { 712 if (key == sensitive_data.host_certificates[i] || 713 (compare && sensitive_data.host_certificates[i] && 714 sshkey_equal(key, 715 sensitive_data.host_certificates[i]))) 716 return (i); 717 } else { 718 if (key == sensitive_data.host_keys[i] || 719 (compare && sensitive_data.host_keys[i] && 720 sshkey_equal(key, sensitive_data.host_keys[i]))) 721 return (i); 722 if (key == sensitive_data.host_pubkeys[i] || 723 (compare && sensitive_data.host_pubkeys[i] && 724 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 725 return (i); 726 } 727 } 728 return (-1); 729 } 730 731 /* Inform the client of all hostkeys */ 732 static void 733 notify_hostkeys(struct ssh *ssh) 734 { 735 struct sshbuf *buf; 736 struct sshkey *key; 737 u_int i, nkeys; 738 int r; 739 char *fp; 740 741 /* Some clients cannot cope with the hostkeys message, skip those. */ 742 if (ssh->compat & SSH_BUG_HOSTKEYS) 743 return; 744 745 if ((buf = sshbuf_new()) == NULL) 746 fatal("%s: sshbuf_new", __func__); 747 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 748 key = get_hostkey_public_by_index(i, ssh); 749 if (key == NULL || key->type == KEY_UNSPEC || 750 sshkey_is_cert(key)) 751 continue; 752 fp = sshkey_fingerprint(key, options.fingerprint_hash, 753 SSH_FP_DEFAULT); 754 debug3("%s: key %d: %s %s", __func__, i, 755 sshkey_ssh_name(key), fp); 756 free(fp); 757 if (nkeys == 0) { 758 /* 759 * Start building the request when we find the 760 * first usable key. 761 */ 762 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 763 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || 764 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ 765 sshpkt_fatal(ssh, r, "%s: start request", __func__); 766 } 767 /* Append the key to the request */ 768 sshbuf_reset(buf); 769 if ((r = sshkey_putb(key, buf)) != 0) 770 fatal("%s: couldn't put hostkey %d: %s", 771 __func__, i, ssh_err(r)); 772 if ((r = sshpkt_put_stringb(ssh, buf)) != 0) 773 sshpkt_fatal(ssh, r, "%s: append key", __func__); 774 nkeys++; 775 } 776 debug3("%s: sent %u hostkeys", __func__, nkeys); 777 if (nkeys == 0) 778 fatal("%s: no hostkeys", __func__); 779 if ((r = sshpkt_send(ssh)) != 0) 780 sshpkt_fatal(ssh, r, "%s: send", __func__); 781 sshbuf_free(buf); 782 } 783 784 /* 785 * returns 1 if connection should be dropped, 0 otherwise. 786 * dropping starts at connection #max_startups_begin with a probability 787 * of (max_startups_rate/100). the probability increases linearly until 788 * all connections are dropped for startups > max_startups 789 */ 790 static int 791 should_drop_connection(int startups) 792 { 793 int p, r; 794 795 if (startups < options.max_startups_begin) 796 return 0; 797 if (startups >= options.max_startups) 798 return 1; 799 if (options.max_startups_rate == 100) 800 return 1; 801 802 p = 100 - options.max_startups_rate; 803 p *= startups - options.max_startups_begin; 804 p /= options.max_startups - options.max_startups_begin; 805 p += options.max_startups_rate; 806 r = arc4random_uniform(100); 807 808 debug("%s: p %d, r %d", __func__, p, r); 809 return (r < p) ? 1 : 0; 810 } 811 812 /* 813 * Check whether connection should be accepted by MaxStartups. 814 * Returns 0 if the connection is accepted. If the connection is refused, 815 * returns 1 and attempts to send notification to client. 816 * Logs when the MaxStartups condition is entered or exited, and periodically 817 * while in that state. 818 */ 819 static int 820 drop_connection(int sock, int startups) 821 { 822 char *laddr, *raddr; 823 const char msg[] = "Exceeded MaxStartups\r\n"; 824 static time_t last_drop, first_drop; 825 static u_int ndropped; 826 LogLevel drop_level = SYSLOG_LEVEL_VERBOSE; 827 time_t now; 828 829 now = monotime(); 830 if (!should_drop_connection(startups)) { 831 if (last_drop != 0 && 832 startups < options.max_startups_begin - 1) { 833 /* XXX maybe need better hysteresis here */ 834 logit("exited MaxStartups throttling after %s, " 835 "%u connections dropped", 836 fmt_timeframe(now - first_drop), ndropped); 837 last_drop = 0; 838 } 839 return 0; 840 } 841 842 #define SSHD_MAXSTARTUPS_LOG_INTERVAL (5 * 60) 843 if (last_drop == 0) { 844 error("beginning MaxStartups throttling"); 845 drop_level = SYSLOG_LEVEL_INFO; 846 first_drop = now; 847 ndropped = 0; 848 } else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) { 849 /* Periodic logs */ 850 error("in MaxStartups throttling for %s, " 851 "%u connections dropped", 852 fmt_timeframe(now - first_drop), ndropped + 1); 853 drop_level = SYSLOG_LEVEL_INFO; 854 } 855 last_drop = now; 856 ndropped++; 857 858 laddr = get_local_ipaddr(sock); 859 raddr = get_peer_ipaddr(sock); 860 do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d " 861 "past MaxStartups", startups, raddr, get_peer_port(sock), 862 laddr, get_local_port(sock)); 863 free(laddr); 864 free(raddr); 865 /* best-effort notification to client */ 866 (void)write(sock, msg, sizeof(msg) - 1); 867 return 1; 868 } 869 870 static void 871 usage(void) 872 { 873 fprintf(stderr, "%s, %s\n", 874 SSH_VERSION, 875 #ifdef WITH_OPENSSL 876 OpenSSL_version(OPENSSL_VERSION) 877 #else 878 "without OpenSSL" 879 #endif 880 ); 881 fprintf(stderr, 882 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 883 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 884 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 885 ); 886 exit(1); 887 } 888 889 static void 890 send_rexec_state(int fd, struct sshbuf *conf) 891 { 892 struct sshbuf *m = NULL, *inc = NULL; 893 struct include_item *item = NULL; 894 int r; 895 896 debug3("%s: entering fd = %d config len %zu", __func__, fd, 897 sshbuf_len(conf)); 898 899 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 900 fatal("%s: sshbuf_new failed", __func__); 901 902 /* pack includes into a string */ 903 TAILQ_FOREACH(item, &includes, entry) { 904 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 905 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 906 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 907 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 908 } 909 910 /* 911 * Protocol from reexec master to child: 912 * string configuration 913 * string included_files[] { 914 * string selector 915 * string filename 916 * string contents 917 * } 918 */ 919 if ((r = sshbuf_put_stringb(m, conf)) != 0 || 920 (r = sshbuf_put_stringb(m, inc)) != 0) 921 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 922 if (ssh_msg_send(fd, 0, m) == -1) 923 error("%s: ssh_msg_send failed", __func__); 924 925 sshbuf_free(m); 926 sshbuf_free(inc); 927 928 debug3("%s: done", __func__); 929 } 930 931 static void 932 recv_rexec_state(int fd, struct sshbuf *conf) 933 { 934 struct sshbuf *m, *inc; 935 u_char *cp, ver; 936 size_t len; 937 int r; 938 struct include_item *item; 939 940 debug3("%s: entering fd = %d", __func__, fd); 941 942 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 943 fatal("%s: sshbuf_new failed", __func__); 944 if (ssh_msg_recv(fd, m) == -1) 945 fatal("%s: ssh_msg_recv failed", __func__); 946 if ((r = sshbuf_get_u8(m, &ver)) != 0) 947 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 948 if (ver != 0) 949 fatal("%s: rexec version mismatch", __func__); 950 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || 951 (r = sshbuf_get_stringb(m, inc)) != 0) 952 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 953 954 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 955 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 956 957 while (sshbuf_len(inc) != 0) { 958 item = xcalloc(1, sizeof(*item)); 959 if ((item->contents = sshbuf_new()) == NULL) 960 fatal("%s: sshbuf_new failed", __func__); 961 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 || 962 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 || 963 (r = sshbuf_get_stringb(inc, item->contents)) != 0) 964 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 965 TAILQ_INSERT_TAIL(&includes, item, entry); 966 } 967 968 free(cp); 969 sshbuf_free(m); 970 971 debug3("%s: done", __func__); 972 } 973 974 /* Accept a connection from inetd */ 975 static void 976 server_accept_inetd(int *sock_in, int *sock_out) 977 { 978 int fd; 979 980 if (rexeced_flag) { 981 close(REEXEC_CONFIG_PASS_FD); 982 *sock_in = *sock_out = dup(STDIN_FILENO); 983 } else { 984 *sock_in = dup(STDIN_FILENO); 985 *sock_out = dup(STDOUT_FILENO); 986 } 987 /* 988 * We intentionally do not close the descriptors 0, 1, and 2 989 * as our code for setting the descriptors won't work if 990 * ttyfd happens to be one of those. 991 */ 992 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 993 dup2(fd, STDIN_FILENO); 994 dup2(fd, STDOUT_FILENO); 995 if (!log_stderr) 996 dup2(fd, STDERR_FILENO); 997 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 998 close(fd); 999 } 1000 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 1001 } 1002 1003 /* 1004 * Listen for TCP connections 1005 */ 1006 static void 1007 listen_on_addrs(struct listenaddr *la) 1008 { 1009 int ret, listen_sock; 1010 struct addrinfo *ai; 1011 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1012 1013 for (ai = la->addrs; ai; ai = ai->ai_next) { 1014 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1015 continue; 1016 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1017 fatal("Too many listen sockets. " 1018 "Enlarge MAX_LISTEN_SOCKS"); 1019 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1020 ntop, sizeof(ntop), strport, sizeof(strport), 1021 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1022 error("getnameinfo failed: %.100s", 1023 ssh_gai_strerror(ret)); 1024 continue; 1025 } 1026 /* Create socket for listening. */ 1027 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1028 ai->ai_protocol); 1029 if (listen_sock == -1) { 1030 /* kernel may not support ipv6 */ 1031 verbose("socket: %.100s", strerror(errno)); 1032 continue; 1033 } 1034 if (set_nonblock(listen_sock) == -1) { 1035 close(listen_sock); 1036 continue; 1037 } 1038 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1039 verbose("socket: CLOEXEC: %s", strerror(errno)); 1040 close(listen_sock); 1041 continue; 1042 } 1043 /* Socket options */ 1044 set_reuseaddr(listen_sock); 1045 if (la->rdomain != NULL && 1046 set_rdomain(listen_sock, la->rdomain) == -1) { 1047 close(listen_sock); 1048 continue; 1049 } 1050 1051 debug("Bind to port %s on %s.", strport, ntop); 1052 1053 /* Bind the socket to the desired port. */ 1054 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 1055 error("Bind to port %s on %s failed: %.200s.", 1056 strport, ntop, strerror(errno)); 1057 close(listen_sock); 1058 continue; 1059 } 1060 listen_socks[num_listen_socks] = listen_sock; 1061 num_listen_socks++; 1062 1063 /* Start listening on the port. */ 1064 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 1065 fatal("listen on [%s]:%s: %.100s", 1066 ntop, strport, strerror(errno)); 1067 logit("Server listening on %s port %s%s%s.", 1068 ntop, strport, 1069 la->rdomain == NULL ? "" : " rdomain ", 1070 la->rdomain == NULL ? "" : la->rdomain); 1071 } 1072 } 1073 1074 static void 1075 server_listen(void) 1076 { 1077 u_int i; 1078 1079 for (i = 0; i < options.num_listen_addrs; i++) { 1080 listen_on_addrs(&options.listen_addrs[i]); 1081 freeaddrinfo(options.listen_addrs[i].addrs); 1082 free(options.listen_addrs[i].rdomain); 1083 memset(&options.listen_addrs[i], 0, 1084 sizeof(options.listen_addrs[i])); 1085 } 1086 free(options.listen_addrs); 1087 options.listen_addrs = NULL; 1088 options.num_listen_addrs = 0; 1089 1090 if (!num_listen_socks) 1091 fatal("Cannot bind any address."); 1092 } 1093 1094 /* 1095 * The main TCP accept loop. Note that, for the non-debug case, returns 1096 * from this function are in a forked subprocess. 1097 */ 1098 static void 1099 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1100 { 1101 fd_set *fdset; 1102 int i, j, ret, maxfd; 1103 int ostartups = -1, startups = 0, listening = 0, lameduck = 0; 1104 int startup_p[2] = { -1 , -1 }; 1105 char c = 0; 1106 struct sockaddr_storage from; 1107 socklen_t fromlen; 1108 pid_t pid; 1109 1110 /* setup fd set for accept */ 1111 fdset = NULL; 1112 maxfd = 0; 1113 for (i = 0; i < num_listen_socks; i++) 1114 if (listen_socks[i] > maxfd) 1115 maxfd = listen_socks[i]; 1116 /* pipes connected to unauthenticated child sshd processes */ 1117 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1118 startup_flags = xcalloc(options.max_startups, sizeof(int)); 1119 for (i = 0; i < options.max_startups; i++) 1120 startup_pipes[i] = -1; 1121 1122 /* 1123 * Stay listening for connections until the system crashes or 1124 * the daemon is killed with a signal. 1125 */ 1126 for (;;) { 1127 if (ostartups != startups) { 1128 setproctitle("%s [listener] %d of %d-%d startups", 1129 listener_proctitle, startups, 1130 options.max_startups_begin, options.max_startups); 1131 ostartups = startups; 1132 } 1133 if (received_sighup) { 1134 if (!lameduck) { 1135 debug("Received SIGHUP; waiting for children"); 1136 close_listen_socks(); 1137 lameduck = 1; 1138 } 1139 if (listening <= 0) 1140 sighup_restart(); 1141 } 1142 free(fdset); 1143 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1144 sizeof(fd_mask)); 1145 1146 for (i = 0; i < num_listen_socks; i++) 1147 FD_SET(listen_socks[i], fdset); 1148 for (i = 0; i < options.max_startups; i++) 1149 if (startup_pipes[i] != -1) 1150 FD_SET(startup_pipes[i], fdset); 1151 1152 /* Wait in select until there is a connection. */ 1153 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1154 if (ret == -1 && errno != EINTR) 1155 error("select: %.100s", strerror(errno)); 1156 if (received_sigterm) { 1157 logit("Received signal %d; terminating.", 1158 (int) received_sigterm); 1159 close_listen_socks(); 1160 if (options.pid_file != NULL) 1161 unlink(options.pid_file); 1162 exit(received_sigterm == SIGTERM ? 0 : 255); 1163 } 1164 if (ret == -1) 1165 continue; 1166 1167 for (i = 0; i < options.max_startups; i++) { 1168 if (startup_pipes[i] == -1 || 1169 !FD_ISSET(startup_pipes[i], fdset)) 1170 continue; 1171 switch (read(startup_pipes[i], &c, sizeof(c))) { 1172 case -1: 1173 if (errno == EINTR || errno == EAGAIN) 1174 continue; 1175 if (errno != EPIPE) { 1176 error("%s: startup pipe %d (fd=%d): " 1177 "read %s", __func__, i, 1178 startup_pipes[i], strerror(errno)); 1179 } 1180 /* FALLTHROUGH */ 1181 case 0: 1182 /* child exited or completed auth */ 1183 close(startup_pipes[i]); 1184 startup_pipes[i] = -1; 1185 startups--; 1186 if (startup_flags[i]) 1187 listening--; 1188 break; 1189 case 1: 1190 /* child has finished preliminaries */ 1191 if (startup_flags[i]) { 1192 listening--; 1193 startup_flags[i] = 0; 1194 } 1195 break; 1196 } 1197 } 1198 for (i = 0; i < num_listen_socks; i++) { 1199 if (!FD_ISSET(listen_socks[i], fdset)) 1200 continue; 1201 fromlen = sizeof(from); 1202 *newsock = accept(listen_socks[i], 1203 (struct sockaddr *)&from, &fromlen); 1204 if (*newsock == -1) { 1205 if (errno != EINTR && errno != EWOULDBLOCK && 1206 errno != ECONNABORTED) 1207 error("accept: %.100s", 1208 strerror(errno)); 1209 if (errno == EMFILE || errno == ENFILE) 1210 usleep(100 * 1000); 1211 continue; 1212 } 1213 if (unset_nonblock(*newsock) == -1 || 1214 drop_connection(*newsock, startups) || 1215 pipe(startup_p) == -1) { 1216 close(*newsock); 1217 continue; 1218 } 1219 1220 if (rexec_flag && socketpair(AF_UNIX, 1221 SOCK_STREAM, 0, config_s) == -1) { 1222 error("reexec socketpair: %s", 1223 strerror(errno)); 1224 close(*newsock); 1225 close(startup_p[0]); 1226 close(startup_p[1]); 1227 continue; 1228 } 1229 1230 for (j = 0; j < options.max_startups; j++) 1231 if (startup_pipes[j] == -1) { 1232 startup_pipes[j] = startup_p[0]; 1233 if (maxfd < startup_p[0]) 1234 maxfd = startup_p[0]; 1235 startups++; 1236 startup_flags[j] = 1; 1237 break; 1238 } 1239 1240 /* 1241 * Got connection. Fork a child to handle it, unless 1242 * we are in debugging mode. 1243 */ 1244 if (debug_flag) { 1245 /* 1246 * In debugging mode. Close the listening 1247 * socket, and start processing the 1248 * connection without forking. 1249 */ 1250 debug("Server will not fork when running in debugging mode."); 1251 close_listen_socks(); 1252 *sock_in = *newsock; 1253 *sock_out = *newsock; 1254 close(startup_p[0]); 1255 close(startup_p[1]); 1256 startup_pipe = -1; 1257 pid = getpid(); 1258 if (rexec_flag) { 1259 send_rexec_state(config_s[0], cfg); 1260 close(config_s[0]); 1261 } 1262 return; 1263 } 1264 1265 /* 1266 * Normal production daemon. Fork, and have 1267 * the child process the connection. The 1268 * parent continues listening. 1269 */ 1270 listening++; 1271 if ((pid = fork()) == 0) { 1272 /* 1273 * Child. Close the listening and 1274 * max_startup sockets. Start using 1275 * the accepted socket. Reinitialize 1276 * logging (since our pid has changed). 1277 * We return from this function to handle 1278 * the connection. 1279 */ 1280 startup_pipe = startup_p[1]; 1281 close_startup_pipes(); 1282 close_listen_socks(); 1283 *sock_in = *newsock; 1284 *sock_out = *newsock; 1285 log_init(__progname, 1286 options.log_level, 1287 options.log_facility, 1288 log_stderr); 1289 if (rexec_flag) 1290 close(config_s[0]); 1291 else { 1292 /* 1293 * Signal parent that the preliminaries 1294 * for this child are complete. For the 1295 * re-exec case, this happens after the 1296 * child has received the rexec state 1297 * from the server. 1298 */ 1299 (void)atomicio(vwrite, startup_pipe, 1300 "\0", 1); 1301 } 1302 return; 1303 } 1304 1305 /* Parent. Stay in the loop. */ 1306 if (pid == -1) 1307 error("fork: %.100s", strerror(errno)); 1308 else 1309 debug("Forked child %ld.", (long)pid); 1310 1311 close(startup_p[1]); 1312 1313 if (rexec_flag) { 1314 close(config_s[1]); 1315 send_rexec_state(config_s[0], cfg); 1316 close(config_s[0]); 1317 } 1318 close(*newsock); 1319 } 1320 } 1321 } 1322 1323 /* 1324 * If IP options are supported, make sure there are none (log and 1325 * return an error if any are found). Basically we are worried about 1326 * source routing; it can be used to pretend you are somebody 1327 * (ip-address) you are not. That itself may be "almost acceptable" 1328 * under certain circumstances, but rhosts authentication is useless 1329 * if source routing is accepted. Notice also that if we just dropped 1330 * source routing here, the other side could use IP spoofing to do 1331 * rest of the interaction and could still bypass security. So we 1332 * exit here if we detect any IP options. 1333 */ 1334 static void 1335 check_ip_options(struct ssh *ssh) 1336 { 1337 int sock_in = ssh_packet_get_connection_in(ssh); 1338 struct sockaddr_storage from; 1339 u_char opts[200]; 1340 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1341 char text[sizeof(opts) * 3 + 1]; 1342 1343 memset(&from, 0, sizeof(from)); 1344 if (getpeername(sock_in, (struct sockaddr *)&from, 1345 &fromlen) == -1) 1346 return; 1347 if (from.ss_family != AF_INET) 1348 return; 1349 /* XXX IPv6 options? */ 1350 1351 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1352 &option_size) >= 0 && option_size != 0) { 1353 text[0] = '\0'; 1354 for (i = 0; i < option_size; i++) 1355 snprintf(text + i*3, sizeof(text) - i*3, 1356 " %2.2x", opts[i]); 1357 fatal("Connection from %.100s port %d with IP opts: %.800s", 1358 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1359 } 1360 return; 1361 } 1362 1363 /* Set the routing domain for this process */ 1364 static void 1365 set_process_rdomain(struct ssh *ssh, const char *name) 1366 { 1367 int rtable, ortable = getrtable(); 1368 const char *errstr; 1369 1370 if (name == NULL) 1371 return; /* default */ 1372 1373 if (strcmp(name, "%D") == 0) { 1374 /* "expands" to routing domain of connection */ 1375 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1376 return; 1377 } 1378 1379 rtable = (int)strtonum(name, 0, 255, &errstr); 1380 if (errstr != NULL) /* Shouldn't happen */ 1381 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1382 if (rtable != ortable && setrtable(rtable) != 0) 1383 fatal("Unable to set routing domain %d: %s", 1384 rtable, strerror(errno)); 1385 debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable); 1386 } 1387 1388 static void 1389 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1390 struct sshkey *key) 1391 { 1392 static struct ssh_digest_ctx *ctx; 1393 u_char *hash; 1394 size_t len; 1395 struct sshbuf *buf; 1396 int r; 1397 1398 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1399 fatal("%s: ssh_digest_start", __func__); 1400 if (key == NULL) { /* finalize */ 1401 /* add server config in case we are using agent for host keys */ 1402 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1403 sshbuf_len(server_cfg)) != 0) 1404 fatal("%s: ssh_digest_update", __func__); 1405 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1406 hash = xmalloc(len); 1407 if (ssh_digest_final(ctx, hash, len) != 0) 1408 fatal("%s: ssh_digest_final", __func__); 1409 options.timing_secret = PEEK_U64(hash); 1410 freezero(hash, len); 1411 ssh_digest_free(ctx); 1412 ctx = NULL; 1413 return; 1414 } 1415 if ((buf = sshbuf_new()) == NULL) 1416 fatal("%s could not allocate buffer", __func__); 1417 if ((r = sshkey_private_serialize(key, buf)) != 0) 1418 fatal("sshkey_private_serialize: %s", ssh_err(r)); 1419 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1420 fatal("%s: ssh_digest_update", __func__); 1421 sshbuf_reset(buf); 1422 sshbuf_free(buf); 1423 } 1424 1425 static char * 1426 prepare_proctitle(int ac, char **av) 1427 { 1428 char *ret = NULL; 1429 int i; 1430 1431 for (i = 0; i < ac; i++) 1432 xextendf(&ret, " ", "%s", av[i]); 1433 return ret; 1434 } 1435 1436 /* 1437 * Main program for the daemon. 1438 */ 1439 int 1440 main(int ac, char **av) 1441 { 1442 struct ssh *ssh = NULL; 1443 extern char *optarg; 1444 extern int optind; 1445 int r, opt, on = 1, already_daemon, remote_port; 1446 int sock_in = -1, sock_out = -1, newsock = -1; 1447 const char *remote_ip, *rdomain; 1448 char *fp, *line, *laddr, *logfile = NULL; 1449 int config_s[2] = { -1 , -1 }; 1450 u_int i, j; 1451 u_int64_t ibytes, obytes; 1452 mode_t new_umask; 1453 struct sshkey *key; 1454 struct sshkey *pubkey; 1455 int keytype; 1456 Authctxt *authctxt; 1457 struct connection_info *connection_info = NULL; 1458 1459 /* Save argv. */ 1460 saved_argv = av; 1461 rexec_argc = ac; 1462 1463 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1464 sanitise_stdfd(); 1465 1466 /* Initialize configuration options to their default values. */ 1467 initialize_server_options(&options); 1468 1469 /* Parse command-line arguments. */ 1470 while ((opt = getopt(ac, av, 1471 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1472 switch (opt) { 1473 case '4': 1474 options.address_family = AF_INET; 1475 break; 1476 case '6': 1477 options.address_family = AF_INET6; 1478 break; 1479 case 'f': 1480 config_file_name = optarg; 1481 break; 1482 case 'c': 1483 servconf_add_hostcert("[command-line]", 0, 1484 &options, optarg); 1485 break; 1486 case 'd': 1487 if (debug_flag == 0) { 1488 debug_flag = 1; 1489 options.log_level = SYSLOG_LEVEL_DEBUG1; 1490 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1491 options.log_level++; 1492 break; 1493 case 'D': 1494 no_daemon_flag = 1; 1495 break; 1496 case 'E': 1497 logfile = optarg; 1498 /* FALLTHROUGH */ 1499 case 'e': 1500 log_stderr = 1; 1501 break; 1502 case 'i': 1503 inetd_flag = 1; 1504 break; 1505 case 'r': 1506 rexec_flag = 0; 1507 break; 1508 case 'R': 1509 rexeced_flag = 1; 1510 inetd_flag = 1; 1511 break; 1512 case 'Q': 1513 /* ignored */ 1514 break; 1515 case 'q': 1516 options.log_level = SYSLOG_LEVEL_QUIET; 1517 break; 1518 case 'b': 1519 /* protocol 1, ignored */ 1520 break; 1521 case 'p': 1522 options.ports_from_cmdline = 1; 1523 if (options.num_ports >= MAX_PORTS) { 1524 fprintf(stderr, "too many ports.\n"); 1525 exit(1); 1526 } 1527 options.ports[options.num_ports++] = a2port(optarg); 1528 if (options.ports[options.num_ports-1] <= 0) { 1529 fprintf(stderr, "Bad port number.\n"); 1530 exit(1); 1531 } 1532 break; 1533 case 'g': 1534 if ((options.login_grace_time = convtime(optarg)) == -1) { 1535 fprintf(stderr, "Invalid login grace time.\n"); 1536 exit(1); 1537 } 1538 break; 1539 case 'k': 1540 /* protocol 1, ignored */ 1541 break; 1542 case 'h': 1543 servconf_add_hostkey("[command-line]", 0, 1544 &options, optarg, 1); 1545 break; 1546 case 't': 1547 test_flag = 1; 1548 break; 1549 case 'T': 1550 test_flag = 2; 1551 break; 1552 case 'C': 1553 connection_info = get_connection_info(ssh, 0, 0); 1554 if (parse_server_match_testspec(connection_info, 1555 optarg) == -1) 1556 exit(1); 1557 break; 1558 case 'u': 1559 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1560 if (utmp_len > HOST_NAME_MAX+1) { 1561 fprintf(stderr, "Invalid utmp length.\n"); 1562 exit(1); 1563 } 1564 break; 1565 case 'o': 1566 line = xstrdup(optarg); 1567 if (process_server_config_line(&options, line, 1568 "command-line", 0, NULL, NULL, &includes) != 0) 1569 exit(1); 1570 free(line); 1571 break; 1572 case '?': 1573 default: 1574 usage(); 1575 break; 1576 } 1577 } 1578 if (rexeced_flag || inetd_flag) 1579 rexec_flag = 0; 1580 if (!test_flag && rexec_flag && !path_absolute(av[0])) 1581 fatal("sshd re-exec requires execution with an absolute path"); 1582 if (rexeced_flag) 1583 closefrom(REEXEC_MIN_FREE_FD); 1584 else 1585 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1586 1587 #ifdef WITH_OPENSSL 1588 OpenSSL_add_all_algorithms(); 1589 #endif 1590 1591 /* If requested, redirect the logs to the specified logfile. */ 1592 if (logfile != NULL) 1593 log_redirect_stderr_to(logfile); 1594 /* 1595 * Force logging to stderr until we have loaded the private host 1596 * key (unless started from inetd) 1597 */ 1598 log_init(__progname, 1599 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1600 SYSLOG_LEVEL_INFO : options.log_level, 1601 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1602 SYSLOG_FACILITY_AUTH : options.log_facility, 1603 log_stderr || !inetd_flag || debug_flag); 1604 1605 sensitive_data.have_ssh2_key = 0; 1606 1607 /* 1608 * If we're not doing an extended test do not silently ignore connection 1609 * test params. 1610 */ 1611 if (test_flag < 2 && connection_info != NULL) 1612 fatal("Config test connection parameter (-C) provided without " 1613 "test mode (-T)"); 1614 1615 /* Fetch our configuration */ 1616 if ((cfg = sshbuf_new()) == NULL) 1617 fatal("%s: sshbuf_new failed", __func__); 1618 if (rexeced_flag) { 1619 setproctitle("%s", "[rexeced]"); 1620 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1621 if (!debug_flag) { 1622 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1623 close(REEXEC_STARTUP_PIPE_FD); 1624 /* 1625 * Signal parent that this child is at a point where 1626 * they can go away if they have a SIGHUP pending. 1627 */ 1628 (void)atomicio(vwrite, startup_pipe, "\0", 1); 1629 } 1630 } else if (strcasecmp(config_file_name, "none") != 0) 1631 load_server_config(config_file_name, cfg); 1632 1633 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1634 cfg, &includes, NULL); 1635 1636 /* Fill in default values for those options not explicitly set. */ 1637 fill_default_server_options(&options); 1638 1639 /* challenge-response is implemented via keyboard interactive */ 1640 if (options.challenge_response_authentication) 1641 options.kbd_interactive_authentication = 1; 1642 1643 /* Check that options are sensible */ 1644 if (options.authorized_keys_command_user == NULL && 1645 (options.authorized_keys_command != NULL && 1646 strcasecmp(options.authorized_keys_command, "none") != 0)) 1647 fatal("AuthorizedKeysCommand set without " 1648 "AuthorizedKeysCommandUser"); 1649 if (options.authorized_principals_command_user == NULL && 1650 (options.authorized_principals_command != NULL && 1651 strcasecmp(options.authorized_principals_command, "none") != 0)) 1652 fatal("AuthorizedPrincipalsCommand set without " 1653 "AuthorizedPrincipalsCommandUser"); 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 for (i = 0; i < options.num_auth_methods; i++) { 1663 if (auth2_methods_valid(options.auth_methods[i], 1664 1) == 0) 1665 break; 1666 } 1667 if (i >= options.num_auth_methods) 1668 fatal("AuthenticationMethods cannot be satisfied by " 1669 "enabled authentication methods"); 1670 } 1671 1672 /* Check that there are no remaining arguments. */ 1673 if (optind < ac) { 1674 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1675 exit(1); 1676 } 1677 1678 debug("sshd version %s, %s", SSH_VERSION, 1679 #ifdef WITH_OPENSSL 1680 OpenSSL_version(OPENSSL_VERSION) 1681 #else 1682 "without OpenSSL" 1683 #endif 1684 ); 1685 1686 /* load host keys */ 1687 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1688 sizeof(struct sshkey *)); 1689 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1690 sizeof(struct sshkey *)); 1691 1692 if (options.host_key_agent) { 1693 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1694 setenv(SSH_AUTHSOCKET_ENV_NAME, 1695 options.host_key_agent, 1); 1696 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1697 have_agent = 1; 1698 else 1699 error("Could not connect to agent \"%s\": %s", 1700 options.host_key_agent, ssh_err(r)); 1701 } 1702 1703 for (i = 0; i < options.num_host_key_files; i++) { 1704 int ll = options.host_key_file_userprovided[i] ? 1705 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1706 1707 if (options.host_key_files[i] == NULL) 1708 continue; 1709 if ((r = sshkey_load_private(options.host_key_files[i], "", 1710 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1711 do_log2(ll, "Unable to load host key \"%s\": %s", 1712 options.host_key_files[i], ssh_err(r)); 1713 if (sshkey_is_sk(key) && 1714 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1715 debug("host key %s requires user presence, ignoring", 1716 options.host_key_files[i]); 1717 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1718 } 1719 if (r == 0 && key != NULL && 1720 (r = sshkey_shield_private(key)) != 0) { 1721 do_log2(ll, "Unable to shield host key \"%s\": %s", 1722 options.host_key_files[i], ssh_err(r)); 1723 sshkey_free(key); 1724 key = NULL; 1725 } 1726 if ((r = sshkey_load_public(options.host_key_files[i], 1727 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1728 do_log2(ll, "Unable to load host key \"%s\": %s", 1729 options.host_key_files[i], ssh_err(r)); 1730 if (pubkey != NULL && key != NULL) { 1731 if (!sshkey_equal(pubkey, key)) { 1732 error("Public key for %s does not match " 1733 "private key", options.host_key_files[i]); 1734 sshkey_free(pubkey); 1735 pubkey = NULL; 1736 } 1737 } 1738 if (pubkey == NULL && key != NULL) { 1739 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1740 fatal("Could not demote key: \"%s\": %s", 1741 options.host_key_files[i], ssh_err(r)); 1742 } 1743 sensitive_data.host_keys[i] = key; 1744 sensitive_data.host_pubkeys[i] = pubkey; 1745 1746 if (key == NULL && pubkey != NULL && have_agent) { 1747 debug("will rely on agent for hostkey %s", 1748 options.host_key_files[i]); 1749 keytype = pubkey->type; 1750 } else if (key != NULL) { 1751 keytype = key->type; 1752 accumulate_host_timing_secret(cfg, key); 1753 } else { 1754 do_log2(ll, "Unable to load host key: %s", 1755 options.host_key_files[i]); 1756 sensitive_data.host_keys[i] = NULL; 1757 sensitive_data.host_pubkeys[i] = NULL; 1758 continue; 1759 } 1760 1761 switch (keytype) { 1762 case KEY_RSA: 1763 case KEY_DSA: 1764 case KEY_ECDSA: 1765 case KEY_ED25519: 1766 case KEY_ECDSA_SK: 1767 case KEY_ED25519_SK: 1768 case KEY_XMSS: 1769 if (have_agent || key != NULL) 1770 sensitive_data.have_ssh2_key = 1; 1771 break; 1772 } 1773 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1774 SSH_FP_DEFAULT)) == NULL) 1775 fatal("sshkey_fingerprint failed"); 1776 debug("%s host key #%d: %s %s", 1777 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1778 free(fp); 1779 } 1780 accumulate_host_timing_secret(cfg, NULL); 1781 if (!sensitive_data.have_ssh2_key) { 1782 logit("sshd: no hostkeys available -- exiting."); 1783 exit(1); 1784 } 1785 1786 /* 1787 * Load certificates. They are stored in an array at identical 1788 * indices to the public keys that they relate to. 1789 */ 1790 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1791 sizeof(struct sshkey *)); 1792 for (i = 0; i < options.num_host_key_files; i++) 1793 sensitive_data.host_certificates[i] = NULL; 1794 1795 for (i = 0; i < options.num_host_cert_files; i++) { 1796 if (options.host_cert_files[i] == NULL) 1797 continue; 1798 if ((r = sshkey_load_public(options.host_cert_files[i], 1799 &key, NULL)) != 0) { 1800 error("Could not load host certificate \"%s\": %s", 1801 options.host_cert_files[i], ssh_err(r)); 1802 continue; 1803 } 1804 if (!sshkey_is_cert(key)) { 1805 error("Certificate file is not a certificate: %s", 1806 options.host_cert_files[i]); 1807 sshkey_free(key); 1808 continue; 1809 } 1810 /* Find matching private key */ 1811 for (j = 0; j < options.num_host_key_files; j++) { 1812 if (sshkey_equal_public(key, 1813 sensitive_data.host_keys[j])) { 1814 sensitive_data.host_certificates[j] = key; 1815 break; 1816 } 1817 } 1818 if (j >= options.num_host_key_files) { 1819 error("No matching private key for certificate: %s", 1820 options.host_cert_files[i]); 1821 sshkey_free(key); 1822 continue; 1823 } 1824 sensitive_data.host_certificates[j] = key; 1825 debug("host certificate: #%u type %d %s", j, key->type, 1826 sshkey_type(key)); 1827 } 1828 1829 if (use_privsep) { 1830 struct stat st; 1831 1832 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1833 fatal("Privilege separation user %s does not exist", 1834 SSH_PRIVSEP_USER); 1835 endpwent(); 1836 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1837 (S_ISDIR(st.st_mode) == 0)) 1838 fatal("Missing privilege separation directory: %s", 1839 _PATH_PRIVSEP_CHROOT_DIR); 1840 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1841 fatal("%s must be owned by root and not group or " 1842 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1843 } 1844 1845 if (test_flag > 1) { 1846 /* 1847 * If no connection info was provided by -C then use 1848 * use a blank one that will cause no predicate to match. 1849 */ 1850 if (connection_info == NULL) 1851 connection_info = get_connection_info(ssh, 0, 0); 1852 connection_info->test = 1; 1853 parse_server_match_config(&options, &includes, connection_info); 1854 dump_config(&options); 1855 } 1856 1857 /* Configuration looks good, so exit if in test mode. */ 1858 if (test_flag) 1859 exit(0); 1860 1861 if (rexec_flag) { 1862 if (rexec_argc < 0) 1863 fatal("rexec_argc %d < 0", rexec_argc); 1864 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1865 for (i = 0; i < (u_int)rexec_argc; i++) { 1866 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1867 rexec_argv[i] = saved_argv[i]; 1868 } 1869 rexec_argv[rexec_argc] = "-R"; 1870 rexec_argv[rexec_argc + 1] = NULL; 1871 } 1872 listener_proctitle = prepare_proctitle(ac, av); 1873 1874 /* Ensure that umask disallows at least group and world write */ 1875 new_umask = umask(0077) | 0022; 1876 (void) umask(new_umask); 1877 1878 /* Initialize the log (it is reinitialized below in case we forked). */ 1879 if (debug_flag && (!inetd_flag || rexeced_flag)) 1880 log_stderr = 1; 1881 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1882 1883 /* 1884 * If not in debugging mode, not started from inetd and not already 1885 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1886 * terminal, and fork. The original process exits. 1887 */ 1888 already_daemon = daemonized(); 1889 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1890 1891 if (daemon(0, 0) == -1) 1892 fatal("daemon() failed: %.200s", strerror(errno)); 1893 1894 disconnect_controlling_tty(); 1895 } 1896 /* Reinitialize the log (because of the fork above). */ 1897 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1898 1899 /* Chdir to the root directory so that the current disk can be 1900 unmounted if desired. */ 1901 if (chdir("/") == -1) 1902 error("chdir(\"/\"): %s", strerror(errno)); 1903 1904 /* ignore SIGPIPE */ 1905 ssh_signal(SIGPIPE, SIG_IGN); 1906 1907 /* Get a connection, either from inetd or a listening TCP socket */ 1908 if (inetd_flag) { 1909 server_accept_inetd(&sock_in, &sock_out); 1910 } else { 1911 server_listen(); 1912 1913 ssh_signal(SIGHUP, sighup_handler); 1914 ssh_signal(SIGCHLD, main_sigchld_handler); 1915 ssh_signal(SIGTERM, sigterm_handler); 1916 ssh_signal(SIGQUIT, sigterm_handler); 1917 1918 /* 1919 * Write out the pid file after the sigterm handler 1920 * is setup and the listen sockets are bound 1921 */ 1922 if (options.pid_file != NULL && !debug_flag) { 1923 FILE *f = fopen(options.pid_file, "w"); 1924 1925 if (f == NULL) { 1926 error("Couldn't create pid file \"%s\": %s", 1927 options.pid_file, strerror(errno)); 1928 } else { 1929 fprintf(f, "%ld\n", (long) getpid()); 1930 fclose(f); 1931 } 1932 } 1933 1934 /* Accept a connection and return in a forked child */ 1935 server_accept_loop(&sock_in, &sock_out, 1936 &newsock, config_s); 1937 } 1938 1939 /* This is the child processing a new connection. */ 1940 setproctitle("%s", "[accepted]"); 1941 1942 /* 1943 * Create a new session and process group since the 4.4BSD 1944 * setlogin() affects the entire process group. We don't 1945 * want the child to be able to affect the parent. 1946 */ 1947 if (!debug_flag && !inetd_flag && setsid() == -1) 1948 error("setsid: %.100s", strerror(errno)); 1949 1950 if (rexec_flag) { 1951 int fd; 1952 1953 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1954 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1955 dup2(newsock, STDIN_FILENO); 1956 dup2(STDIN_FILENO, STDOUT_FILENO); 1957 if (startup_pipe == -1) 1958 close(REEXEC_STARTUP_PIPE_FD); 1959 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1960 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1961 close(startup_pipe); 1962 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1963 } 1964 1965 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1966 close(config_s[1]); 1967 1968 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 1969 execv(rexec_argv[0], rexec_argv); 1970 1971 /* Reexec has failed, fall back and continue */ 1972 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1973 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1974 log_init(__progname, options.log_level, 1975 options.log_facility, log_stderr); 1976 1977 /* Clean up fds */ 1978 close(REEXEC_CONFIG_PASS_FD); 1979 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1980 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1981 dup2(fd, STDIN_FILENO); 1982 dup2(fd, STDOUT_FILENO); 1983 if (fd > STDERR_FILENO) 1984 close(fd); 1985 } 1986 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1987 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1988 } 1989 1990 /* Executed child processes don't need these. */ 1991 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1992 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1993 1994 /* We will not restart on SIGHUP since it no longer makes sense. */ 1995 ssh_signal(SIGALRM, SIG_DFL); 1996 ssh_signal(SIGHUP, SIG_DFL); 1997 ssh_signal(SIGTERM, SIG_DFL); 1998 ssh_signal(SIGQUIT, SIG_DFL); 1999 ssh_signal(SIGCHLD, SIG_DFL); 2000 2001 /* 2002 * Register our connection. This turns encryption off because we do 2003 * not have a key. 2004 */ 2005 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 2006 fatal("Unable to create connection"); 2007 the_active_state = ssh; 2008 ssh_packet_set_server(ssh); 2009 2010 check_ip_options(ssh); 2011 2012 /* Prepare the channels layer */ 2013 channel_init_channels(ssh); 2014 channel_set_af(ssh, options.address_family); 2015 process_permitopen(ssh, &options); 2016 2017 /* Set SO_KEEPALIVE if requested. */ 2018 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 2019 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) 2020 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2021 2022 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2023 debug("ssh_remote_port failed"); 2024 cleanup_exit(255); 2025 } 2026 2027 /* 2028 * The rest of the code depends on the fact that 2029 * ssh_remote_ipaddr() caches the remote ip, even if 2030 * the socket goes away. 2031 */ 2032 remote_ip = ssh_remote_ipaddr(ssh); 2033 2034 rdomain = ssh_packet_rdomain_in(ssh); 2035 2036 /* Log the connection. */ 2037 laddr = get_local_ipaddr(sock_in); 2038 verbose("Connection from %s port %d on %s port %d%s%s%s", 2039 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2040 rdomain == NULL ? "" : " rdomain \"", 2041 rdomain == NULL ? "" : rdomain, 2042 rdomain == NULL ? "" : "\""); 2043 free(laddr); 2044 2045 /* 2046 * We don't want to listen forever unless the other side 2047 * successfully authenticates itself. So we set up an alarm which is 2048 * cleared after successful authentication. A limit of zero 2049 * indicates no limit. Note that we don't set the alarm in debugging 2050 * mode; it is just annoying to have the server exit just when you 2051 * are about to discover the bug. 2052 */ 2053 ssh_signal(SIGALRM, grace_alarm_handler); 2054 if (!debug_flag) 2055 alarm(options.login_grace_time); 2056 2057 if ((r = kex_exchange_identification(ssh, -1, 2058 options.version_addendum)) != 0) 2059 sshpkt_fatal(ssh, r, "banner exchange"); 2060 2061 ssh_packet_set_nonblocking(ssh); 2062 2063 /* allocate authentication context */ 2064 authctxt = xcalloc(1, sizeof(*authctxt)); 2065 ssh->authctxt = authctxt; 2066 2067 /* XXX global for cleanup, access from other modules */ 2068 the_authctxt = authctxt; 2069 2070 /* Set default key authentication options */ 2071 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2072 fatal("allocation failed"); 2073 2074 /* prepare buffer to collect messages to display to user after login */ 2075 if ((loginmsg = sshbuf_new()) == NULL) 2076 fatal("%s: sshbuf_new failed", __func__); 2077 auth_debug_reset(); 2078 2079 if (use_privsep) { 2080 if (privsep_preauth(ssh) == 1) 2081 goto authenticated; 2082 } else if (have_agent) { 2083 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2084 error("Unable to get agent socket: %s", ssh_err(r)); 2085 have_agent = 0; 2086 } 2087 } 2088 2089 /* perform the key exchange */ 2090 /* authenticate user and start session */ 2091 do_ssh2_kex(ssh); 2092 do_authentication2(ssh); 2093 2094 /* 2095 * If we use privilege separation, the unprivileged child transfers 2096 * the current keystate and exits 2097 */ 2098 if (use_privsep) { 2099 mm_send_keystate(ssh, pmonitor); 2100 ssh_packet_clear_keys(ssh); 2101 exit(0); 2102 } 2103 2104 authenticated: 2105 /* 2106 * Cancel the alarm we set to limit the time taken for 2107 * authentication. 2108 */ 2109 alarm(0); 2110 ssh_signal(SIGALRM, SIG_DFL); 2111 authctxt->authenticated = 1; 2112 if (startup_pipe != -1) { 2113 close(startup_pipe); 2114 startup_pipe = -1; 2115 } 2116 2117 if (options.routing_domain != NULL) 2118 set_process_rdomain(ssh, options.routing_domain); 2119 2120 /* 2121 * In privilege separation, we fork another child and prepare 2122 * file descriptor passing. 2123 */ 2124 if (use_privsep) { 2125 privsep_postauth(ssh, authctxt); 2126 /* the monitor process [priv] will not return */ 2127 } 2128 2129 ssh_packet_set_timeout(ssh, options.client_alive_interval, 2130 options.client_alive_count_max); 2131 2132 /* Try to send all our hostkeys to the client */ 2133 notify_hostkeys(ssh); 2134 2135 /* Start session. */ 2136 do_authenticated(ssh, authctxt); 2137 2138 /* The connection has been terminated. */ 2139 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 2140 verbose("Transferred: sent %llu, received %llu bytes", 2141 (unsigned long long)obytes, (unsigned long long)ibytes); 2142 2143 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2144 ssh_packet_close(ssh); 2145 2146 if (use_privsep) 2147 mm_terminate(); 2148 2149 exit(0); 2150 } 2151 2152 int 2153 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 2154 struct sshkey *pubkey, u_char **signature, size_t *slenp, 2155 const u_char *data, size_t dlen, const char *alg) 2156 { 2157 int r; 2158 2159 if (use_privsep) { 2160 if (privkey) { 2161 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 2162 data, dlen, alg, options.sk_provider, 2163 ssh->compat) < 0) 2164 fatal("%s: privkey sign failed", __func__); 2165 } else { 2166 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 2167 data, dlen, alg, options.sk_provider, 2168 ssh->compat) < 0) 2169 fatal("%s: pubkey sign failed", __func__); 2170 } 2171 } else { 2172 if (privkey) { 2173 if (sshkey_sign(privkey, signature, slenp, data, dlen, 2174 alg, options.sk_provider, ssh->compat) < 0) 2175 fatal("%s: privkey sign failed", __func__); 2176 } else { 2177 if ((r = ssh_agent_sign(auth_sock, pubkey, 2178 signature, slenp, data, dlen, alg, 2179 ssh->compat)) != 0) { 2180 fatal("%s: agent sign failed: %s", 2181 __func__, ssh_err(r)); 2182 } 2183 } 2184 } 2185 return 0; 2186 } 2187 2188 /* SSH2 key exchange */ 2189 static void 2190 do_ssh2_kex(struct ssh *ssh) 2191 { 2192 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2193 struct kex *kex; 2194 int r; 2195 2196 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2197 options.kex_algorithms); 2198 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2199 options.ciphers); 2200 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2201 options.ciphers); 2202 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2203 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2204 2205 if (options.compression == COMP_NONE) { 2206 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2207 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2208 } 2209 2210 if (options.rekey_limit || options.rekey_interval) 2211 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 2212 options.rekey_interval); 2213 2214 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2215 list_hostkey_types()); 2216 2217 /* start key exchange */ 2218 if ((r = kex_setup(ssh, myproposal)) != 0) 2219 fatal("kex_setup: %s", ssh_err(r)); 2220 kex = ssh->kex; 2221 #ifdef WITH_OPENSSL 2222 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 2223 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 2224 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 2225 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 2226 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 2227 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2228 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2229 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 2230 #endif 2231 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 2232 kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_server; 2233 kex->load_host_public_key=&get_hostkey_public_by_type; 2234 kex->load_host_private_key=&get_hostkey_private_by_type; 2235 kex->host_key_index=&get_hostkey_index; 2236 kex->sign = sshd_hostkey_sign; 2237 2238 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 2239 2240 session_id2 = kex->session_id; 2241 session_id2_len = kex->session_id_len; 2242 2243 #ifdef DEBUG_KEXDH 2244 /* send 1st encrypted/maced/compressed message */ 2245 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 2246 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 2247 (r = sshpkt_send(ssh)) != 0 || 2248 (r = ssh_packet_write_wait(ssh)) != 0) 2249 fatal("%s: send test: %s", __func__, ssh_err(r)); 2250 #endif 2251 debug("KEX done"); 2252 } 2253 2254 /* server specific fatal cleanup */ 2255 void 2256 cleanup_exit(int i) 2257 { 2258 if (the_active_state != NULL && the_authctxt != NULL) { 2259 do_cleanup(the_active_state, the_authctxt); 2260 if (use_privsep && privsep_is_preauth && 2261 pmonitor != NULL && pmonitor->m_pid > 1) { 2262 debug("Killing privsep child %d", pmonitor->m_pid); 2263 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2264 errno != ESRCH) 2265 error("%s: kill(%d): %s", __func__, 2266 pmonitor->m_pid, strerror(errno)); 2267 } 2268 } 2269 _exit(i); 2270 } 2271