1 /* $OpenBSD: sshd.c,v 1.582 2021/11/18 03:07:59 djm 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 <poll.h> 59 #include <pwd.h> 60 #include <signal.h> 61 #include <stdio.h> 62 #include <stdlib.h> 63 #include <string.h> 64 #include <stdarg.h> 65 #include <unistd.h> 66 #include <limits.h> 67 68 #ifdef WITH_OPENSSL 69 #include <openssl/bn.h> 70 #endif 71 72 #include "xmalloc.h" 73 #include "ssh.h" 74 #include "ssh2.h" 75 #include "sshpty.h" 76 #include "packet.h" 77 #include "log.h" 78 #include "sshbuf.h" 79 #include "misc.h" 80 #include "match.h" 81 #include "servconf.h" 82 #include "uidswap.h" 83 #include "compat.h" 84 #include "cipher.h" 85 #include "digest.h" 86 #include "sshkey.h" 87 #include "kex.h" 88 #include "myproposal.h" 89 #include "authfile.h" 90 #include "pathnames.h" 91 #include "atomicio.h" 92 #include "canohost.h" 93 #include "hostfile.h" 94 #include "auth.h" 95 #include "authfd.h" 96 #include "msg.h" 97 #include "dispatch.h" 98 #include "channels.h" 99 #include "session.h" 100 #include "monitor.h" 101 #ifdef GSSAPI 102 #include "ssh-gss.h" 103 #endif 104 #include "monitor_wrap.h" 105 #include "ssh-sandbox.h" 106 #include "auth-options.h" 107 #include "version.h" 108 #include "ssherr.h" 109 #include "sk-api.h" 110 #include "srclimit.h" 111 #include "dh.h" 112 113 /* Re-exec fds */ 114 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 115 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 116 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 117 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 118 119 extern char *__progname; 120 121 /* Server configuration options. */ 122 ServerOptions options; 123 124 /* Name of the server configuration file. */ 125 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 126 127 /* 128 * Debug mode flag. This can be set on the command line. If debug 129 * mode is enabled, extra debugging output will be sent to the system 130 * log, the daemon will not go to background, and will exit after processing 131 * the first connection. 132 */ 133 int debug_flag = 0; 134 135 /* 136 * Indicating that the daemon should only test the configuration and keys. 137 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 138 * configuration, optionally using connection information provided by the 139 * "-C" flag. 140 */ 141 static int test_flag = 0; 142 143 /* Flag indicating that the daemon is being started from inetd. */ 144 static int inetd_flag = 0; 145 146 /* Flag indicating that sshd should not detach and become a daemon. */ 147 static int no_daemon_flag = 0; 148 149 /* debug goes to stderr unless inetd_flag is set */ 150 static int log_stderr = 0; 151 152 /* Saved arguments to main(). */ 153 static char **saved_argv; 154 155 /* re-exec */ 156 static int rexeced_flag = 0; 157 static int rexec_flag = 1; 158 static int rexec_argc = 0; 159 static char **rexec_argv; 160 161 /* 162 * The sockets that the server is listening; this is used in the SIGHUP 163 * signal handler. 164 */ 165 #define MAX_LISTEN_SOCKS 16 166 static int listen_socks[MAX_LISTEN_SOCKS]; 167 static int num_listen_socks = 0; 168 169 /* Daemon's agent connection */ 170 int auth_sock = -1; 171 static int have_agent = 0; 172 173 /* 174 * Any really sensitive data in the application is contained in this 175 * structure. The idea is that this structure could be locked into memory so 176 * that the pages do not get written into swap. However, there are some 177 * problems. The private key contains BIGNUMs, and we do not (in principle) 178 * have access to the internals of them, and locking just the structure is 179 * not very useful. Currently, memory locking is not implemented. 180 */ 181 struct { 182 struct sshkey **host_keys; /* all private host keys */ 183 struct sshkey **host_pubkeys; /* all public host keys */ 184 struct sshkey **host_certificates; /* all public host certificates */ 185 int have_ssh2_key; 186 } sensitive_data; 187 188 /* This is set to true when a signal is received. */ 189 static volatile sig_atomic_t received_sighup = 0; 190 static volatile sig_atomic_t received_sigterm = 0; 191 192 /* record remote hostname or ip */ 193 u_int utmp_len = HOST_NAME_MAX+1; 194 195 /* 196 * startup_pipes/flags are used for tracking children of the listening sshd 197 * process early in their lifespans. This tracking is needed for three things: 198 * 199 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 200 * connections. 201 * 2) Avoiding a race condition for SIGHUP processing, where child processes 202 * may have listen_socks open that could collide with main listener process 203 * after it restarts. 204 * 3) Ensuring that rexec'd sshd processes have received their initial state 205 * from the parent listen process before handling SIGHUP. 206 * 207 * Child processes signal that they have completed closure of the listen_socks 208 * and (if applicable) received their rexec state by sending a char over their 209 * sock. Child processes signal that authentication has completed by closing 210 * the sock (or by exiting). 211 */ 212 static int *startup_pipes = NULL; 213 static int *startup_flags = NULL; /* Indicates child closed listener */ 214 static int startup_pipe = -1; /* in child */ 215 216 /* variables used for privilege separation */ 217 int use_privsep = -1; 218 struct monitor *pmonitor = NULL; 219 int privsep_is_preauth = 1; 220 221 /* global connection state and authentication contexts */ 222 Authctxt *the_authctxt = NULL; 223 struct ssh *the_active_state; 224 225 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 226 struct sshauthopt *auth_opts = NULL; 227 228 /* sshd_config buffer */ 229 struct sshbuf *cfg; 230 231 /* Included files from the configuration file */ 232 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 233 234 /* message to be displayed after login */ 235 struct sshbuf *loginmsg; 236 237 /* Prototypes for various functions defined later in this file. */ 238 void destroy_sensitive_data(void); 239 void demote_sensitive_data(void); 240 static void do_ssh2_kex(struct ssh *); 241 242 static char *listener_proctitle; 243 244 /* 245 * Close all listening sockets 246 */ 247 static void 248 close_listen_socks(void) 249 { 250 int i; 251 252 for (i = 0; i < num_listen_socks; i++) 253 close(listen_socks[i]); 254 num_listen_socks = 0; 255 } 256 257 static void 258 close_startup_pipes(void) 259 { 260 int i; 261 262 if (startup_pipes) 263 for (i = 0; i < options.max_startups; i++) 264 if (startup_pipes[i] != -1) 265 close(startup_pipes[i]); 266 } 267 268 /* 269 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 270 * the effect is to reread the configuration file (and to regenerate 271 * the server key). 272 */ 273 274 /*ARGSUSED*/ 275 static void 276 sighup_handler(int sig) 277 { 278 received_sighup = 1; 279 } 280 281 /* 282 * Called from the main program after receiving SIGHUP. 283 * Restarts the server. 284 */ 285 static void 286 sighup_restart(void) 287 { 288 logit("Received SIGHUP; restarting."); 289 if (options.pid_file != NULL) 290 unlink(options.pid_file); 291 close_listen_socks(); 292 close_startup_pipes(); 293 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 294 execv(saved_argv[0], saved_argv); 295 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 296 strerror(errno)); 297 exit(1); 298 } 299 300 /* 301 * Generic signal handler for terminating signals in the master daemon. 302 */ 303 /*ARGSUSED*/ 304 static void 305 sigterm_handler(int sig) 306 { 307 received_sigterm = sig; 308 } 309 310 /* 311 * SIGCHLD handler. This is called whenever a child dies. This will then 312 * reap any zombies left by exited children. 313 */ 314 /*ARGSUSED*/ 315 static void 316 main_sigchld_handler(int sig) 317 { 318 int save_errno = errno; 319 pid_t pid; 320 int status; 321 322 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 323 (pid == -1 && errno == EINTR)) 324 ; 325 errno = save_errno; 326 } 327 328 /* 329 * Signal handler for the alarm after the login grace period has expired. 330 */ 331 /*ARGSUSED*/ 332 static void 333 grace_alarm_handler(int sig) 334 { 335 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 336 kill(pmonitor->m_pid, SIGALRM); 337 338 /* 339 * Try to kill any processes that we have spawned, E.g. authorized 340 * keys command helpers. 341 */ 342 if (getpgid(0) == getpid()) { 343 ssh_signal(SIGTERM, SIG_IGN); 344 kill(0, SIGTERM); 345 } 346 347 /* Log error and exit. */ 348 if (use_privsep && pmonitor != NULL && pmonitor->m_pid <= 0) 349 cleanup_exit(255); /* don't log in privsep child */ 350 else { 351 sigdie("Timeout before authentication for %s port %d", 352 ssh_remote_ipaddr(the_active_state), 353 ssh_remote_port(the_active_state)); 354 } 355 } 356 357 /* Destroy the host and server keys. They will no longer be needed. */ 358 void 359 destroy_sensitive_data(void) 360 { 361 u_int i; 362 363 for (i = 0; i < options.num_host_key_files; i++) { 364 if (sensitive_data.host_keys[i]) { 365 sshkey_free(sensitive_data.host_keys[i]); 366 sensitive_data.host_keys[i] = NULL; 367 } 368 if (sensitive_data.host_certificates[i]) { 369 sshkey_free(sensitive_data.host_certificates[i]); 370 sensitive_data.host_certificates[i] = NULL; 371 } 372 } 373 } 374 375 /* Demote private to public keys for network child */ 376 void 377 demote_sensitive_data(void) 378 { 379 struct sshkey *tmp; 380 u_int i; 381 int r; 382 383 for (i = 0; i < options.num_host_key_files; i++) { 384 if (sensitive_data.host_keys[i]) { 385 if ((r = sshkey_from_private( 386 sensitive_data.host_keys[i], &tmp)) != 0) 387 fatal_r(r, "could not demote host %s key", 388 sshkey_type(sensitive_data.host_keys[i])); 389 sshkey_free(sensitive_data.host_keys[i]); 390 sensitive_data.host_keys[i] = tmp; 391 } 392 /* Certs do not need demotion */ 393 } 394 } 395 396 static void 397 privsep_preauth_child(void) 398 { 399 gid_t gidset[1]; 400 struct passwd *pw; 401 402 /* Enable challenge-response authentication for privilege separation */ 403 privsep_challenge_enable(); 404 405 #ifdef GSSAPI 406 /* Cache supported mechanism OIDs for later use */ 407 ssh_gssapi_prepare_supported_oids(); 408 #endif 409 410 /* Demote the private keys to public keys. */ 411 demote_sensitive_data(); 412 413 /* Demote the child */ 414 if (getuid() == 0 || geteuid() == 0) { 415 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) 416 fatal("Privilege separation user %s does not exist", 417 SSH_PRIVSEP_USER); 418 pw = pwcopy(pw); /* Ensure mutable */ 419 endpwent(); 420 freezero(pw->pw_passwd, strlen(pw->pw_passwd)); 421 422 /* Change our root directory */ 423 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 424 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 425 strerror(errno)); 426 if (chdir("/") == -1) 427 fatal("chdir(\"/\"): %s", strerror(errno)); 428 429 /* 430 * Drop our privileges 431 * NB. Can't use setusercontext() after chroot. 432 */ 433 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, 434 (u_int)pw->pw_gid); 435 gidset[0] = pw->pw_gid; 436 if (setgroups(1, gidset) == -1) 437 fatal("setgroups: %.100s", strerror(errno)); 438 permanently_set_uid(pw); 439 } 440 } 441 442 static int 443 privsep_preauth(struct ssh *ssh) 444 { 445 int status, r; 446 pid_t pid; 447 struct ssh_sandbox *box = NULL; 448 449 /* Set up unprivileged child process to deal with network data */ 450 pmonitor = monitor_init(); 451 /* Store a pointer to the kex for later rekeying */ 452 pmonitor->m_pkex = &ssh->kex; 453 454 if (use_privsep == PRIVSEP_ON) 455 box = ssh_sandbox_init(); 456 pid = fork(); 457 if (pid == -1) { 458 fatal("fork of unprivileged child failed"); 459 } else if (pid != 0) { 460 debug2("Network child is on pid %ld", (long)pid); 461 462 pmonitor->m_pid = pid; 463 if (have_agent) { 464 r = ssh_get_authentication_socket(&auth_sock); 465 if (r != 0) { 466 error_r(r, "Could not get agent socket"); 467 have_agent = 0; 468 } 469 } 470 if (box != NULL) 471 ssh_sandbox_parent_preauth(box, pid); 472 monitor_child_preauth(ssh, pmonitor); 473 474 /* Wait for the child's exit status */ 475 while (waitpid(pid, &status, 0) == -1) { 476 if (errno == EINTR) 477 continue; 478 pmonitor->m_pid = -1; 479 fatal_f("waitpid: %s", strerror(errno)); 480 } 481 privsep_is_preauth = 0; 482 pmonitor->m_pid = -1; 483 if (WIFEXITED(status)) { 484 if (WEXITSTATUS(status) != 0) 485 fatal_f("preauth child exited with status %d", 486 WEXITSTATUS(status)); 487 } else if (WIFSIGNALED(status)) 488 fatal_f("preauth child terminated by signal %d", 489 WTERMSIG(status)); 490 if (box != NULL) 491 ssh_sandbox_parent_finish(box); 492 return 1; 493 } else { 494 /* child */ 495 close(pmonitor->m_sendfd); 496 close(pmonitor->m_log_recvfd); 497 498 /* Arrange for logging to be sent to the monitor */ 499 set_log_handler(mm_log_handler, pmonitor); 500 501 privsep_preauth_child(); 502 setproctitle("%s", "[net]"); 503 if (box != NULL) 504 ssh_sandbox_child(box); 505 506 return 0; 507 } 508 } 509 510 static void 511 privsep_postauth(struct ssh *ssh, Authctxt *authctxt) 512 { 513 if (authctxt->pw->pw_uid == 0) { 514 /* File descriptor passing is broken or root login */ 515 use_privsep = 0; 516 goto skip; 517 } 518 519 /* New socket pair */ 520 monitor_reinit(pmonitor); 521 522 pmonitor->m_pid = fork(); 523 if (pmonitor->m_pid == -1) 524 fatal("fork of unprivileged child failed"); 525 else if (pmonitor->m_pid != 0) { 526 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 527 sshbuf_reset(loginmsg); 528 monitor_clear_keystate(ssh, pmonitor); 529 monitor_child_postauth(ssh, pmonitor); 530 531 /* NEVERREACHED */ 532 exit(0); 533 } 534 535 /* child */ 536 537 close(pmonitor->m_sendfd); 538 pmonitor->m_sendfd = -1; 539 540 /* Demote the private keys to public keys. */ 541 demote_sensitive_data(); 542 543 /* Drop privileges */ 544 do_setusercontext(authctxt->pw); 545 546 skip: 547 /* It is safe now to apply the key state */ 548 monitor_apply_keystate(ssh, pmonitor); 549 550 /* 551 * Tell the packet layer that authentication was successful, since 552 * this information is not part of the key state. 553 */ 554 ssh_packet_set_authenticated(ssh); 555 } 556 557 static void 558 append_hostkey_type(struct sshbuf *b, const char *s) 559 { 560 int r; 561 562 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 563 debug3_f("%s key not permitted by HostkeyAlgorithms", s); 564 return; 565 } 566 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 567 fatal_fr(r, "sshbuf_putf"); 568 } 569 570 static char * 571 list_hostkey_types(void) 572 { 573 struct sshbuf *b; 574 struct sshkey *key; 575 char *ret; 576 u_int i; 577 578 if ((b = sshbuf_new()) == NULL) 579 fatal_f("sshbuf_new failed"); 580 for (i = 0; i < options.num_host_key_files; i++) { 581 key = sensitive_data.host_keys[i]; 582 if (key == NULL) 583 key = sensitive_data.host_pubkeys[i]; 584 if (key == NULL) 585 continue; 586 switch (key->type) { 587 case KEY_RSA: 588 /* for RSA we also support SHA2 signatures */ 589 append_hostkey_type(b, "rsa-sha2-512"); 590 append_hostkey_type(b, "rsa-sha2-256"); 591 /* FALLTHROUGH */ 592 case KEY_DSA: 593 case KEY_ECDSA: 594 case KEY_ED25519: 595 case KEY_ECDSA_SK: 596 case KEY_ED25519_SK: 597 case KEY_XMSS: 598 append_hostkey_type(b, sshkey_ssh_name(key)); 599 break; 600 } 601 /* If the private key has a cert peer, then list that too */ 602 key = sensitive_data.host_certificates[i]; 603 if (key == NULL) 604 continue; 605 switch (key->type) { 606 case KEY_RSA_CERT: 607 /* for RSA we also support SHA2 signatures */ 608 append_hostkey_type(b, 609 "rsa-sha2-512-cert-v01@openssh.com"); 610 append_hostkey_type(b, 611 "rsa-sha2-256-cert-v01@openssh.com"); 612 /* FALLTHROUGH */ 613 case KEY_DSA_CERT: 614 case KEY_ECDSA_CERT: 615 case KEY_ED25519_CERT: 616 case KEY_ECDSA_SK_CERT: 617 case KEY_ED25519_SK_CERT: 618 case KEY_XMSS_CERT: 619 append_hostkey_type(b, sshkey_ssh_name(key)); 620 break; 621 } 622 } 623 if ((ret = sshbuf_dup_string(b)) == NULL) 624 fatal_f("sshbuf_dup_string failed"); 625 sshbuf_free(b); 626 debug_f("%s", ret); 627 return ret; 628 } 629 630 static struct sshkey * 631 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 632 { 633 u_int i; 634 struct sshkey *key; 635 636 for (i = 0; i < options.num_host_key_files; i++) { 637 switch (type) { 638 case KEY_RSA_CERT: 639 case KEY_DSA_CERT: 640 case KEY_ECDSA_CERT: 641 case KEY_ED25519_CERT: 642 case KEY_ECDSA_SK_CERT: 643 case KEY_ED25519_SK_CERT: 644 case KEY_XMSS_CERT: 645 key = sensitive_data.host_certificates[i]; 646 break; 647 default: 648 key = sensitive_data.host_keys[i]; 649 if (key == NULL && !need_private) 650 key = sensitive_data.host_pubkeys[i]; 651 break; 652 } 653 if (key == NULL || key->type != type) 654 continue; 655 switch (type) { 656 case KEY_ECDSA: 657 case KEY_ECDSA_SK: 658 case KEY_ECDSA_CERT: 659 case KEY_ECDSA_SK_CERT: 660 if (key->ecdsa_nid != nid) 661 continue; 662 /* FALLTHROUGH */ 663 default: 664 return need_private ? 665 sensitive_data.host_keys[i] : key; 666 } 667 } 668 return NULL; 669 } 670 671 struct sshkey * 672 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 673 { 674 return get_hostkey_by_type(type, nid, 0, ssh); 675 } 676 677 struct sshkey * 678 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 679 { 680 return get_hostkey_by_type(type, nid, 1, ssh); 681 } 682 683 struct sshkey * 684 get_hostkey_by_index(int ind) 685 { 686 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 687 return (NULL); 688 return (sensitive_data.host_keys[ind]); 689 } 690 691 struct sshkey * 692 get_hostkey_public_by_index(int ind, struct ssh *ssh) 693 { 694 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 695 return (NULL); 696 return (sensitive_data.host_pubkeys[ind]); 697 } 698 699 int 700 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 701 { 702 u_int i; 703 704 for (i = 0; i < options.num_host_key_files; i++) { 705 if (sshkey_is_cert(key)) { 706 if (key == sensitive_data.host_certificates[i] || 707 (compare && sensitive_data.host_certificates[i] && 708 sshkey_equal(key, 709 sensitive_data.host_certificates[i]))) 710 return (i); 711 } else { 712 if (key == sensitive_data.host_keys[i] || 713 (compare && sensitive_data.host_keys[i] && 714 sshkey_equal(key, sensitive_data.host_keys[i]))) 715 return (i); 716 if (key == sensitive_data.host_pubkeys[i] || 717 (compare && sensitive_data.host_pubkeys[i] && 718 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 719 return (i); 720 } 721 } 722 return (-1); 723 } 724 725 /* Inform the client of all hostkeys */ 726 static void 727 notify_hostkeys(struct ssh *ssh) 728 { 729 struct sshbuf *buf; 730 struct sshkey *key; 731 u_int i, nkeys; 732 int r; 733 char *fp; 734 735 /* Some clients cannot cope with the hostkeys message, skip those. */ 736 if (ssh->compat & SSH_BUG_HOSTKEYS) 737 return; 738 739 if ((buf = sshbuf_new()) == NULL) 740 fatal_f("sshbuf_new"); 741 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 742 key = get_hostkey_public_by_index(i, ssh); 743 if (key == NULL || key->type == KEY_UNSPEC || 744 sshkey_is_cert(key)) 745 continue; 746 fp = sshkey_fingerprint(key, options.fingerprint_hash, 747 SSH_FP_DEFAULT); 748 debug3_f("key %d: %s %s", i, sshkey_ssh_name(key), fp); 749 free(fp); 750 if (nkeys == 0) { 751 /* 752 * Start building the request when we find the 753 * first usable key. 754 */ 755 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 756 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || 757 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ 758 sshpkt_fatal(ssh, r, "%s: start request", __func__); 759 } 760 /* Append the key to the request */ 761 sshbuf_reset(buf); 762 if ((r = sshkey_putb(key, buf)) != 0) 763 fatal_fr(r, "couldn't put hostkey %d", i); 764 if ((r = sshpkt_put_stringb(ssh, buf)) != 0) 765 sshpkt_fatal(ssh, r, "%s: append key", __func__); 766 nkeys++; 767 } 768 debug3_f("sent %u hostkeys", nkeys); 769 if (nkeys == 0) 770 fatal_f("no hostkeys"); 771 if ((r = sshpkt_send(ssh)) != 0) 772 sshpkt_fatal(ssh, r, "%s: send", __func__); 773 sshbuf_free(buf); 774 } 775 776 /* 777 * returns 1 if connection should be dropped, 0 otherwise. 778 * dropping starts at connection #max_startups_begin with a probability 779 * of (max_startups_rate/100). the probability increases linearly until 780 * all connections are dropped for startups > max_startups 781 */ 782 static int 783 should_drop_connection(int startups) 784 { 785 int p, r; 786 787 if (startups < options.max_startups_begin) 788 return 0; 789 if (startups >= options.max_startups) 790 return 1; 791 if (options.max_startups_rate == 100) 792 return 1; 793 794 p = 100 - options.max_startups_rate; 795 p *= startups - options.max_startups_begin; 796 p /= options.max_startups - options.max_startups_begin; 797 p += options.max_startups_rate; 798 r = arc4random_uniform(100); 799 800 debug_f("p %d, r %d", p, r); 801 return (r < p) ? 1 : 0; 802 } 803 804 /* 805 * Check whether connection should be accepted by MaxStartups. 806 * Returns 0 if the connection is accepted. If the connection is refused, 807 * returns 1 and attempts to send notification to client. 808 * Logs when the MaxStartups condition is entered or exited, and periodically 809 * while in that state. 810 */ 811 static int 812 drop_connection(int sock, int startups, int notify_pipe) 813 { 814 char *laddr, *raddr; 815 const char msg[] = "Exceeded MaxStartups\r\n"; 816 static time_t last_drop, first_drop; 817 static u_int ndropped; 818 LogLevel drop_level = SYSLOG_LEVEL_VERBOSE; 819 time_t now; 820 821 now = monotime(); 822 if (!should_drop_connection(startups) && 823 srclimit_check_allow(sock, notify_pipe) == 1) { 824 if (last_drop != 0 && 825 startups < options.max_startups_begin - 1) { 826 /* XXX maybe need better hysteresis here */ 827 logit("exited MaxStartups throttling after %s, " 828 "%u connections dropped", 829 fmt_timeframe(now - first_drop), ndropped); 830 last_drop = 0; 831 } 832 return 0; 833 } 834 835 #define SSHD_MAXSTARTUPS_LOG_INTERVAL (5 * 60) 836 if (last_drop == 0) { 837 error("beginning MaxStartups throttling"); 838 drop_level = SYSLOG_LEVEL_INFO; 839 first_drop = now; 840 ndropped = 0; 841 } else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) { 842 /* Periodic logs */ 843 error("in MaxStartups throttling for %s, " 844 "%u connections dropped", 845 fmt_timeframe(now - first_drop), ndropped + 1); 846 drop_level = SYSLOG_LEVEL_INFO; 847 } 848 last_drop = now; 849 ndropped++; 850 851 laddr = get_local_ipaddr(sock); 852 raddr = get_peer_ipaddr(sock); 853 do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d " 854 "past MaxStartups", startups, raddr, get_peer_port(sock), 855 laddr, get_local_port(sock)); 856 free(laddr); 857 free(raddr); 858 /* best-effort notification to client */ 859 (void)write(sock, msg, sizeof(msg) - 1); 860 return 1; 861 } 862 863 static void 864 usage(void) 865 { 866 fprintf(stderr, "%s, %s\n", SSH_VERSION, SSH_OPENSSL_VERSION); 867 fprintf(stderr, 868 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 869 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 870 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 871 ); 872 exit(1); 873 } 874 875 static void 876 send_rexec_state(int fd, struct sshbuf *conf) 877 { 878 struct sshbuf *m = NULL, *inc = NULL; 879 struct include_item *item = NULL; 880 int r; 881 882 debug3_f("entering fd = %d config len %zu", fd, 883 sshbuf_len(conf)); 884 885 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 886 fatal_f("sshbuf_new failed"); 887 888 /* pack includes into a string */ 889 TAILQ_FOREACH(item, &includes, entry) { 890 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 891 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 892 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 893 fatal_fr(r, "compose includes"); 894 } 895 896 /* 897 * Protocol from reexec master to child: 898 * string configuration 899 * string included_files[] { 900 * string selector 901 * string filename 902 * string contents 903 * } 904 */ 905 if ((r = sshbuf_put_stringb(m, conf)) != 0 || 906 (r = sshbuf_put_stringb(m, inc)) != 0) 907 fatal_fr(r, "compose config"); 908 if (ssh_msg_send(fd, 0, m) == -1) 909 error_f("ssh_msg_send failed"); 910 911 sshbuf_free(m); 912 sshbuf_free(inc); 913 914 debug3_f("done"); 915 } 916 917 static void 918 recv_rexec_state(int fd, struct sshbuf *conf) 919 { 920 struct sshbuf *m, *inc; 921 u_char *cp, ver; 922 size_t len; 923 int r; 924 struct include_item *item; 925 926 debug3_f("entering fd = %d", fd); 927 928 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 929 fatal_f("sshbuf_new failed"); 930 if (ssh_msg_recv(fd, m) == -1) 931 fatal_f("ssh_msg_recv failed"); 932 if ((r = sshbuf_get_u8(m, &ver)) != 0) 933 fatal_fr(r, "parse version"); 934 if (ver != 0) 935 fatal_f("rexec version mismatch"); 936 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || 937 (r = sshbuf_get_stringb(m, inc)) != 0) 938 fatal_fr(r, "parse config"); 939 940 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 941 fatal_fr(r, "sshbuf_put"); 942 943 while (sshbuf_len(inc) != 0) { 944 item = xcalloc(1, sizeof(*item)); 945 if ((item->contents = sshbuf_new()) == NULL) 946 fatal_f("sshbuf_new failed"); 947 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 || 948 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 || 949 (r = sshbuf_get_stringb(inc, item->contents)) != 0) 950 fatal_fr(r, "parse includes"); 951 TAILQ_INSERT_TAIL(&includes, item, entry); 952 } 953 954 free(cp); 955 sshbuf_free(m); 956 957 debug3_f("done"); 958 } 959 960 /* Accept a connection from inetd */ 961 static void 962 server_accept_inetd(int *sock_in, int *sock_out) 963 { 964 if (rexeced_flag) { 965 close(REEXEC_CONFIG_PASS_FD); 966 *sock_in = *sock_out = dup(STDIN_FILENO); 967 } else { 968 *sock_in = dup(STDIN_FILENO); 969 *sock_out = dup(STDOUT_FILENO); 970 } 971 /* 972 * We intentionally do not close the descriptors 0, 1, and 2 973 * as our code for setting the descriptors won't work if 974 * ttyfd happens to be one of those. 975 */ 976 if (stdfd_devnull(1, 1, !log_stderr) == -1) 977 error_f("stdfd_devnull failed"); 978 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 979 } 980 981 /* 982 * Listen for TCP connections 983 */ 984 static void 985 listen_on_addrs(struct listenaddr *la) 986 { 987 int ret, listen_sock; 988 struct addrinfo *ai; 989 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 990 991 for (ai = la->addrs; ai; ai = ai->ai_next) { 992 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 993 continue; 994 if (num_listen_socks >= MAX_LISTEN_SOCKS) 995 fatal("Too many listen sockets. " 996 "Enlarge MAX_LISTEN_SOCKS"); 997 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 998 ntop, sizeof(ntop), strport, sizeof(strport), 999 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1000 error("getnameinfo failed: %.100s", 1001 ssh_gai_strerror(ret)); 1002 continue; 1003 } 1004 /* Create socket for listening. */ 1005 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1006 ai->ai_protocol); 1007 if (listen_sock == -1) { 1008 /* kernel may not support ipv6 */ 1009 verbose("socket: %.100s", strerror(errno)); 1010 continue; 1011 } 1012 if (set_nonblock(listen_sock) == -1) { 1013 close(listen_sock); 1014 continue; 1015 } 1016 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1017 verbose("socket: CLOEXEC: %s", strerror(errno)); 1018 close(listen_sock); 1019 continue; 1020 } 1021 /* Socket options */ 1022 set_reuseaddr(listen_sock); 1023 if (la->rdomain != NULL && 1024 set_rdomain(listen_sock, la->rdomain) == -1) { 1025 close(listen_sock); 1026 continue; 1027 } 1028 1029 debug("Bind to port %s on %s.", strport, ntop); 1030 1031 /* Bind the socket to the desired port. */ 1032 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 1033 error("Bind to port %s on %s failed: %.200s.", 1034 strport, ntop, strerror(errno)); 1035 close(listen_sock); 1036 continue; 1037 } 1038 listen_socks[num_listen_socks] = listen_sock; 1039 num_listen_socks++; 1040 1041 /* Start listening on the port. */ 1042 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 1043 fatal("listen on [%s]:%s: %.100s", 1044 ntop, strport, strerror(errno)); 1045 logit("Server listening on %s port %s%s%s.", 1046 ntop, strport, 1047 la->rdomain == NULL ? "" : " rdomain ", 1048 la->rdomain == NULL ? "" : la->rdomain); 1049 } 1050 } 1051 1052 static void 1053 server_listen(void) 1054 { 1055 u_int i; 1056 1057 /* Initialise per-source limit tracking. */ 1058 srclimit_init(options.max_startups, options.per_source_max_startups, 1059 options.per_source_masklen_ipv4, options.per_source_masklen_ipv6); 1060 1061 for (i = 0; i < options.num_listen_addrs; i++) { 1062 listen_on_addrs(&options.listen_addrs[i]); 1063 freeaddrinfo(options.listen_addrs[i].addrs); 1064 free(options.listen_addrs[i].rdomain); 1065 memset(&options.listen_addrs[i], 0, 1066 sizeof(options.listen_addrs[i])); 1067 } 1068 free(options.listen_addrs); 1069 options.listen_addrs = NULL; 1070 options.num_listen_addrs = 0; 1071 1072 if (!num_listen_socks) 1073 fatal("Cannot bind any address."); 1074 } 1075 1076 /* 1077 * The main TCP accept loop. Note that, for the non-debug case, returns 1078 * from this function are in a forked subprocess. 1079 */ 1080 static void 1081 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1082 { 1083 struct pollfd *pfd = NULL; 1084 int i, j, ret; 1085 int ostartups = -1, startups = 0, listening = 0, lameduck = 0; 1086 int startup_p[2] = { -1 , -1 }; 1087 char c = 0; 1088 struct sockaddr_storage from; 1089 socklen_t fromlen; 1090 pid_t pid; 1091 sigset_t nsigset, osigset; 1092 1093 /* setup fd set for accept */ 1094 /* pipes connected to unauthenticated child sshd processes */ 1095 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1096 startup_flags = xcalloc(options.max_startups, sizeof(int)); 1097 for (i = 0; i < options.max_startups; i++) 1098 startup_pipes[i] = -1; 1099 1100 /* 1101 * Prepare signal mask that we use to block signals that might set 1102 * received_sigterm or received_sighup, so that we are guaranteed 1103 * to immediately wake up the ppoll if a signal is received after 1104 * the flag is checked. 1105 */ 1106 sigemptyset(&nsigset); 1107 sigaddset(&nsigset, SIGHUP); 1108 sigaddset(&nsigset, SIGCHLD); 1109 sigaddset(&nsigset, SIGTERM); 1110 sigaddset(&nsigset, SIGQUIT); 1111 1112 pfd = xcalloc(num_listen_socks + options.max_startups, 1113 sizeof(struct pollfd)); 1114 1115 /* 1116 * Stay listening for connections until the system crashes or 1117 * the daemon is killed with a signal. 1118 */ 1119 for (;;) { 1120 sigprocmask(SIG_BLOCK, &nsigset, &osigset); 1121 if (received_sigterm) { 1122 logit("Received signal %d; terminating.", 1123 (int) received_sigterm); 1124 close_listen_socks(); 1125 if (options.pid_file != NULL) 1126 unlink(options.pid_file); 1127 exit(received_sigterm == SIGTERM ? 0 : 255); 1128 } 1129 if (ostartups != startups) { 1130 setproctitle("%s [listener] %d of %d-%d startups", 1131 listener_proctitle, startups, 1132 options.max_startups_begin, options.max_startups); 1133 ostartups = startups; 1134 } 1135 if (received_sighup) { 1136 if (!lameduck) { 1137 debug("Received SIGHUP; waiting for children"); 1138 close_listen_socks(); 1139 lameduck = 1; 1140 } 1141 if (listening <= 0) { 1142 sigprocmask(SIG_SETMASK, &osigset, NULL); 1143 sighup_restart(); 1144 } 1145 } 1146 1147 for (i = 0; i < num_listen_socks; i++) { 1148 pfd[i].fd = listen_socks[i]; 1149 pfd[i].events = POLLIN; 1150 } 1151 for (i = 0; i < options.max_startups; i++) { 1152 pfd[num_listen_socks+i].fd = startup_pipes[i]; 1153 if (startup_pipes[i] != -1) 1154 pfd[num_listen_socks+i].events = POLLIN; 1155 } 1156 1157 /* Wait until a connection arrives or a child exits. */ 1158 ret = ppoll(pfd, num_listen_socks + options.max_startups, 1159 NULL, &osigset); 1160 if (ret == -1 && errno != EINTR) 1161 error("ppoll: %.100s", strerror(errno)); 1162 sigprocmask(SIG_SETMASK, &osigset, NULL); 1163 if (ret == -1) 1164 continue; 1165 1166 for (i = 0; i < options.max_startups; i++) { 1167 if (startup_pipes[i] == -1 || 1168 !(pfd[num_listen_socks+i].revents & (POLLIN|POLLHUP))) 1169 continue; 1170 switch (read(startup_pipes[i], &c, sizeof(c))) { 1171 case -1: 1172 if (errno == EINTR || errno == EAGAIN) 1173 continue; 1174 if (errno != EPIPE) { 1175 error_f("startup pipe %d (fd=%d): " 1176 "read %s", i, startup_pipes[i], 1177 strerror(errno)); 1178 } 1179 /* FALLTHROUGH */ 1180 case 0: 1181 /* child exited or completed auth */ 1182 close(startup_pipes[i]); 1183 srclimit_done(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 (!(pfd[i].revents & POLLIN)) 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 pipe(startup_p) == -1) { 1215 close(*newsock); 1216 continue; 1217 } 1218 if (drop_connection(*newsock, startups, startup_p[0])) { 1219 close(*newsock); 1220 close(startup_p[0]); 1221 close(startup_p[1]); 1222 continue; 1223 } 1224 1225 if (rexec_flag && socketpair(AF_UNIX, 1226 SOCK_STREAM, 0, config_s) == -1) { 1227 error("reexec socketpair: %s", 1228 strerror(errno)); 1229 close(*newsock); 1230 close(startup_p[0]); 1231 close(startup_p[1]); 1232 continue; 1233 } 1234 1235 for (j = 0; j < options.max_startups; j++) 1236 if (startup_pipes[j] == -1) { 1237 startup_pipes[j] = startup_p[0]; 1238 startups++; 1239 startup_flags[j] = 1; 1240 break; 1241 } 1242 1243 /* 1244 * Got connection. Fork a child to handle it, unless 1245 * we are in debugging mode. 1246 */ 1247 if (debug_flag) { 1248 /* 1249 * In debugging mode. Close the listening 1250 * socket, and start processing the 1251 * connection without forking. 1252 */ 1253 debug("Server will not fork when running in debugging mode."); 1254 close_listen_socks(); 1255 *sock_in = *newsock; 1256 *sock_out = *newsock; 1257 close(startup_p[0]); 1258 close(startup_p[1]); 1259 startup_pipe = -1; 1260 pid = getpid(); 1261 if (rexec_flag) { 1262 send_rexec_state(config_s[0], cfg); 1263 close(config_s[0]); 1264 } 1265 free(pfd); 1266 return; 1267 } 1268 1269 /* 1270 * Normal production daemon. Fork, and have 1271 * the child process the connection. The 1272 * parent continues listening. 1273 */ 1274 listening++; 1275 if ((pid = fork()) == 0) { 1276 /* 1277 * Child. Close the listening and 1278 * max_startup sockets. Start using 1279 * the accepted socket. Reinitialize 1280 * logging (since our pid has changed). 1281 * We return from this function to handle 1282 * the connection. 1283 */ 1284 startup_pipe = startup_p[1]; 1285 close_startup_pipes(); 1286 close_listen_socks(); 1287 *sock_in = *newsock; 1288 *sock_out = *newsock; 1289 log_init(__progname, 1290 options.log_level, 1291 options.log_facility, 1292 log_stderr); 1293 if (rexec_flag) 1294 close(config_s[0]); 1295 else { 1296 /* 1297 * Signal parent that the preliminaries 1298 * for this child are complete. For the 1299 * re-exec case, this happens after the 1300 * child has received the rexec state 1301 * from the server. 1302 */ 1303 (void)atomicio(vwrite, startup_pipe, 1304 "\0", 1); 1305 } 1306 free(pfd); 1307 return; 1308 } 1309 1310 /* Parent. Stay in the loop. */ 1311 if (pid == -1) 1312 error("fork: %.100s", strerror(errno)); 1313 else 1314 debug("Forked child %ld.", (long)pid); 1315 1316 close(startup_p[1]); 1317 1318 if (rexec_flag) { 1319 close(config_s[1]); 1320 send_rexec_state(config_s[0], cfg); 1321 close(config_s[0]); 1322 } 1323 close(*newsock); 1324 } 1325 } 1326 } 1327 1328 /* 1329 * If IP options are supported, make sure there are none (log and 1330 * return an error if any are found). Basically we are worried about 1331 * source routing; it can be used to pretend you are somebody 1332 * (ip-address) you are not. That itself may be "almost acceptable" 1333 * under certain circumstances, but rhosts authentication is useless 1334 * if source routing is accepted. Notice also that if we just dropped 1335 * source routing here, the other side could use IP spoofing to do 1336 * rest of the interaction and could still bypass security. So we 1337 * exit here if we detect any IP options. 1338 */ 1339 static void 1340 check_ip_options(struct ssh *ssh) 1341 { 1342 int sock_in = ssh_packet_get_connection_in(ssh); 1343 struct sockaddr_storage from; 1344 u_char opts[200]; 1345 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1346 char text[sizeof(opts) * 3 + 1]; 1347 1348 memset(&from, 0, sizeof(from)); 1349 if (getpeername(sock_in, (struct sockaddr *)&from, 1350 &fromlen) == -1) 1351 return; 1352 if (from.ss_family != AF_INET) 1353 return; 1354 /* XXX IPv6 options? */ 1355 1356 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1357 &option_size) >= 0 && option_size != 0) { 1358 text[0] = '\0'; 1359 for (i = 0; i < option_size; i++) 1360 snprintf(text + i*3, sizeof(text) - i*3, 1361 " %2.2x", opts[i]); 1362 fatal("Connection from %.100s port %d with IP opts: %.800s", 1363 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1364 } 1365 return; 1366 } 1367 1368 /* Set the routing domain for this process */ 1369 static void 1370 set_process_rdomain(struct ssh *ssh, const char *name) 1371 { 1372 int rtable, ortable = getrtable(); 1373 const char *errstr; 1374 1375 if (name == NULL) 1376 return; /* default */ 1377 1378 if (strcmp(name, "%D") == 0) { 1379 /* "expands" to routing domain of connection */ 1380 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1381 return; 1382 } 1383 1384 rtable = (int)strtonum(name, 0, 255, &errstr); 1385 if (errstr != NULL) /* Shouldn't happen */ 1386 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1387 if (rtable != ortable && setrtable(rtable) != 0) 1388 fatal("Unable to set routing domain %d: %s", 1389 rtable, strerror(errno)); 1390 debug_f("set routing domain %d (was %d)", rtable, ortable); 1391 } 1392 1393 static void 1394 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1395 struct sshkey *key) 1396 { 1397 static struct ssh_digest_ctx *ctx; 1398 u_char *hash; 1399 size_t len; 1400 struct sshbuf *buf; 1401 int r; 1402 1403 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1404 fatal_f("ssh_digest_start"); 1405 if (key == NULL) { /* finalize */ 1406 /* add server config in case we are using agent for host keys */ 1407 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1408 sshbuf_len(server_cfg)) != 0) 1409 fatal_f("ssh_digest_update"); 1410 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1411 hash = xmalloc(len); 1412 if (ssh_digest_final(ctx, hash, len) != 0) 1413 fatal_f("ssh_digest_final"); 1414 options.timing_secret = PEEK_U64(hash); 1415 freezero(hash, len); 1416 ssh_digest_free(ctx); 1417 ctx = NULL; 1418 return; 1419 } 1420 if ((buf = sshbuf_new()) == NULL) 1421 fatal_f("could not allocate buffer"); 1422 if ((r = sshkey_private_serialize(key, buf)) != 0) 1423 fatal_fr(r, "decode key"); 1424 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1425 fatal_f("ssh_digest_update"); 1426 sshbuf_reset(buf); 1427 sshbuf_free(buf); 1428 } 1429 1430 static char * 1431 prepare_proctitle(int ac, char **av) 1432 { 1433 char *ret = NULL; 1434 int i; 1435 1436 for (i = 0; i < ac; i++) 1437 xextendf(&ret, " ", "%s", av[i]); 1438 return ret; 1439 } 1440 1441 /* 1442 * Main program for the daemon. 1443 */ 1444 int 1445 main(int ac, char **av) 1446 { 1447 struct ssh *ssh = NULL; 1448 extern char *optarg; 1449 extern int optind; 1450 int r, opt, on = 1, already_daemon, remote_port; 1451 int sock_in = -1, sock_out = -1, newsock = -1; 1452 const char *remote_ip, *rdomain; 1453 char *fp, *line, *laddr, *logfile = NULL; 1454 int config_s[2] = { -1 , -1 }; 1455 u_int i, j; 1456 u_int64_t ibytes, obytes; 1457 mode_t new_umask; 1458 struct sshkey *key; 1459 struct sshkey *pubkey; 1460 int keytype; 1461 Authctxt *authctxt; 1462 struct connection_info *connection_info = NULL; 1463 1464 /* Save argv. */ 1465 saved_argv = av; 1466 rexec_argc = ac; 1467 1468 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1469 sanitise_stdfd(); 1470 1471 /* Initialize configuration options to their default values. */ 1472 initialize_server_options(&options); 1473 1474 /* Parse command-line arguments. */ 1475 while ((opt = getopt(ac, av, 1476 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1477 switch (opt) { 1478 case '4': 1479 options.address_family = AF_INET; 1480 break; 1481 case '6': 1482 options.address_family = AF_INET6; 1483 break; 1484 case 'f': 1485 config_file_name = optarg; 1486 break; 1487 case 'c': 1488 servconf_add_hostcert("[command-line]", 0, 1489 &options, optarg); 1490 break; 1491 case 'd': 1492 if (debug_flag == 0) { 1493 debug_flag = 1; 1494 options.log_level = SYSLOG_LEVEL_DEBUG1; 1495 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1496 options.log_level++; 1497 break; 1498 case 'D': 1499 no_daemon_flag = 1; 1500 break; 1501 case 'E': 1502 logfile = optarg; 1503 /* FALLTHROUGH */ 1504 case 'e': 1505 log_stderr = 1; 1506 break; 1507 case 'i': 1508 inetd_flag = 1; 1509 break; 1510 case 'r': 1511 rexec_flag = 0; 1512 break; 1513 case 'R': 1514 rexeced_flag = 1; 1515 inetd_flag = 1; 1516 break; 1517 case 'Q': 1518 /* ignored */ 1519 break; 1520 case 'q': 1521 options.log_level = SYSLOG_LEVEL_QUIET; 1522 break; 1523 case 'b': 1524 /* protocol 1, ignored */ 1525 break; 1526 case 'p': 1527 options.ports_from_cmdline = 1; 1528 if (options.num_ports >= MAX_PORTS) { 1529 fprintf(stderr, "too many ports.\n"); 1530 exit(1); 1531 } 1532 options.ports[options.num_ports++] = a2port(optarg); 1533 if (options.ports[options.num_ports-1] <= 0) { 1534 fprintf(stderr, "Bad port number.\n"); 1535 exit(1); 1536 } 1537 break; 1538 case 'g': 1539 if ((options.login_grace_time = convtime(optarg)) == -1) { 1540 fprintf(stderr, "Invalid login grace time.\n"); 1541 exit(1); 1542 } 1543 break; 1544 case 'k': 1545 /* protocol 1, ignored */ 1546 break; 1547 case 'h': 1548 servconf_add_hostkey("[command-line]", 0, 1549 &options, optarg, 1); 1550 break; 1551 case 't': 1552 test_flag = 1; 1553 break; 1554 case 'T': 1555 test_flag = 2; 1556 break; 1557 case 'C': 1558 connection_info = get_connection_info(ssh, 0, 0); 1559 if (parse_server_match_testspec(connection_info, 1560 optarg) == -1) 1561 exit(1); 1562 break; 1563 case 'u': 1564 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1565 if (utmp_len > HOST_NAME_MAX+1) { 1566 fprintf(stderr, "Invalid utmp length.\n"); 1567 exit(1); 1568 } 1569 break; 1570 case 'o': 1571 line = xstrdup(optarg); 1572 if (process_server_config_line(&options, line, 1573 "command-line", 0, NULL, NULL, &includes) != 0) 1574 exit(1); 1575 free(line); 1576 break; 1577 case '?': 1578 default: 1579 usage(); 1580 break; 1581 } 1582 } 1583 if (rexeced_flag || inetd_flag) 1584 rexec_flag = 0; 1585 if (!test_flag && rexec_flag && !path_absolute(av[0])) 1586 fatal("sshd re-exec requires execution with an absolute path"); 1587 if (rexeced_flag) 1588 closefrom(REEXEC_MIN_FREE_FD); 1589 else 1590 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1591 1592 #ifdef WITH_OPENSSL 1593 OpenSSL_add_all_algorithms(); 1594 #endif 1595 1596 /* If requested, redirect the logs to the specified logfile. */ 1597 if (logfile != NULL) 1598 log_redirect_stderr_to(logfile); 1599 /* 1600 * Force logging to stderr until we have loaded the private host 1601 * key (unless started from inetd) 1602 */ 1603 log_init(__progname, 1604 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1605 SYSLOG_LEVEL_INFO : options.log_level, 1606 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1607 SYSLOG_FACILITY_AUTH : options.log_facility, 1608 log_stderr || !inetd_flag || debug_flag); 1609 1610 sensitive_data.have_ssh2_key = 0; 1611 1612 /* 1613 * If we're not doing an extended test do not silently ignore connection 1614 * test params. 1615 */ 1616 if (test_flag < 2 && connection_info != NULL) 1617 fatal("Config test connection parameter (-C) provided without " 1618 "test mode (-T)"); 1619 1620 /* Fetch our configuration */ 1621 if ((cfg = sshbuf_new()) == NULL) 1622 fatal_f("sshbuf_new failed"); 1623 if (rexeced_flag) { 1624 setproctitle("%s", "[rexeced]"); 1625 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1626 if (!debug_flag) { 1627 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1628 close(REEXEC_STARTUP_PIPE_FD); 1629 /* 1630 * Signal parent that this child is at a point where 1631 * they can go away if they have a SIGHUP pending. 1632 */ 1633 (void)atomicio(vwrite, startup_pipe, "\0", 1); 1634 } 1635 } else if (strcasecmp(config_file_name, "none") != 0) 1636 load_server_config(config_file_name, cfg); 1637 1638 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1639 cfg, &includes, NULL); 1640 1641 #ifdef WITH_OPENSSL 1642 if (options.moduli_file != NULL) 1643 dh_set_moduli_file(options.moduli_file); 1644 #endif 1645 1646 /* Fill in default values for those options not explicitly set. */ 1647 fill_default_server_options(&options); 1648 1649 /* Check that options are sensible */ 1650 if (options.authorized_keys_command_user == NULL && 1651 (options.authorized_keys_command != NULL && 1652 strcasecmp(options.authorized_keys_command, "none") != 0)) 1653 fatal("AuthorizedKeysCommand set without " 1654 "AuthorizedKeysCommandUser"); 1655 if (options.authorized_principals_command_user == NULL && 1656 (options.authorized_principals_command != NULL && 1657 strcasecmp(options.authorized_principals_command, "none") != 0)) 1658 fatal("AuthorizedPrincipalsCommand set without " 1659 "AuthorizedPrincipalsCommandUser"); 1660 1661 /* 1662 * Check whether there is any path through configured auth methods. 1663 * Unfortunately it is not possible to verify this generally before 1664 * daemonisation in the presence of Match block, but this catches 1665 * and warns for trivial misconfigurations that could break login. 1666 */ 1667 if (options.num_auth_methods != 0) { 1668 for (i = 0; i < options.num_auth_methods; i++) { 1669 if (auth2_methods_valid(options.auth_methods[i], 1670 1) == 0) 1671 break; 1672 } 1673 if (i >= options.num_auth_methods) 1674 fatal("AuthenticationMethods cannot be satisfied by " 1675 "enabled authentication methods"); 1676 } 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, SSH_OPENSSL_VERSION); 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_r(r, "Could not connect to agent \"%s\"", 1700 options.host_key_agent); 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_r(r, ll, "Unable to load host key \"%s\"", 1712 options.host_key_files[i]); 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_r(r, ll, "Unable to shield host key \"%s\"", 1722 options.host_key_files[i]); 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_r(r, ll, "Unable to load host key \"%s\"", 1729 options.host_key_files[i]); 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_r(r, "Could not demote key: \"%s\"", 1741 options.host_key_files[i]); 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_r(r, "Could not load host certificate \"%s\"", 1801 options.host_cert_files[i]); 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_pubkeys[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, 1882 options.log_facility, log_stderr); 1883 for (i = 0; i < options.num_log_verbose; i++) 1884 log_verbose_add(options.log_verbose[i]); 1885 1886 /* 1887 * If not in debugging mode, not started from inetd and not already 1888 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1889 * terminal, and fork. The original process exits. 1890 */ 1891 already_daemon = daemonized(); 1892 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1893 1894 if (daemon(0, 0) == -1) 1895 fatal("daemon() failed: %.200s", strerror(errno)); 1896 1897 disconnect_controlling_tty(); 1898 } 1899 /* Reinitialize the log (because of the fork above). */ 1900 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1901 1902 /* 1903 * Chdir to the root directory so that the current disk can be 1904 * unmounted if desired. 1905 */ 1906 if (chdir("/") == -1) 1907 error("chdir(\"/\"): %s", strerror(errno)); 1908 1909 /* ignore SIGPIPE */ 1910 ssh_signal(SIGPIPE, SIG_IGN); 1911 1912 /* Get a connection, either from inetd or a listening TCP socket */ 1913 if (inetd_flag) { 1914 server_accept_inetd(&sock_in, &sock_out); 1915 } else { 1916 server_listen(); 1917 1918 ssh_signal(SIGHUP, sighup_handler); 1919 ssh_signal(SIGCHLD, main_sigchld_handler); 1920 ssh_signal(SIGTERM, sigterm_handler); 1921 ssh_signal(SIGQUIT, sigterm_handler); 1922 1923 /* 1924 * Write out the pid file after the sigterm handler 1925 * is setup and the listen sockets are bound 1926 */ 1927 if (options.pid_file != NULL && !debug_flag) { 1928 FILE *f = fopen(options.pid_file, "w"); 1929 1930 if (f == NULL) { 1931 error("Couldn't create pid file \"%s\": %s", 1932 options.pid_file, strerror(errno)); 1933 } else { 1934 fprintf(f, "%ld\n", (long) getpid()); 1935 fclose(f); 1936 } 1937 } 1938 1939 /* Accept a connection and return in a forked child */ 1940 server_accept_loop(&sock_in, &sock_out, 1941 &newsock, config_s); 1942 } 1943 1944 /* This is the child processing a new connection. */ 1945 setproctitle("%s", "[accepted]"); 1946 1947 /* 1948 * Create a new session and process group since the 4.4BSD 1949 * setlogin() affects the entire process group. We don't 1950 * want the child to be able to affect the parent. 1951 */ 1952 if (!debug_flag && !inetd_flag && setsid() == -1) 1953 error("setsid: %.100s", strerror(errno)); 1954 1955 if (rexec_flag) { 1956 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1957 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1958 dup2(newsock, STDIN_FILENO); 1959 dup2(STDIN_FILENO, STDOUT_FILENO); 1960 if (startup_pipe == -1) 1961 close(REEXEC_STARTUP_PIPE_FD); 1962 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1963 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1964 close(startup_pipe); 1965 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1966 } 1967 1968 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1969 close(config_s[1]); 1970 1971 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 1972 execv(rexec_argv[0], rexec_argv); 1973 1974 /* Reexec has failed, fall back and continue */ 1975 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1976 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1977 log_init(__progname, options.log_level, 1978 options.log_facility, log_stderr); 1979 1980 /* Clean up fds */ 1981 close(REEXEC_CONFIG_PASS_FD); 1982 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1983 if (stdfd_devnull(1, 1, 0) == -1) 1984 error_f("stdfd_devnull failed"); 1985 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1986 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1987 } 1988 1989 /* Executed child processes don't need these. */ 1990 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1991 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1992 1993 /* We will not restart on SIGHUP since it no longer makes sense. */ 1994 ssh_signal(SIGALRM, SIG_DFL); 1995 ssh_signal(SIGHUP, SIG_DFL); 1996 ssh_signal(SIGTERM, SIG_DFL); 1997 ssh_signal(SIGQUIT, SIG_DFL); 1998 ssh_signal(SIGCHLD, SIG_DFL); 1999 2000 /* 2001 * Register our connection. This turns encryption off because we do 2002 * not have a key. 2003 */ 2004 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 2005 fatal("Unable to create connection"); 2006 the_active_state = ssh; 2007 ssh_packet_set_server(ssh); 2008 2009 check_ip_options(ssh); 2010 2011 /* Prepare the channels layer */ 2012 channel_init_channels(ssh); 2013 channel_set_af(ssh, options.address_family); 2014 process_permitopen(ssh, &options); 2015 2016 /* Set SO_KEEPALIVE if requested. */ 2017 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 2018 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) 2019 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2020 2021 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2022 debug("ssh_remote_port failed"); 2023 cleanup_exit(255); 2024 } 2025 2026 /* 2027 * The rest of the code depends on the fact that 2028 * ssh_remote_ipaddr() caches the remote ip, even if 2029 * the socket goes away. 2030 */ 2031 remote_ip = ssh_remote_ipaddr(ssh); 2032 2033 rdomain = ssh_packet_rdomain_in(ssh); 2034 2035 /* Log the connection. */ 2036 laddr = get_local_ipaddr(sock_in); 2037 verbose("Connection from %s port %d on %s port %d%s%s%s", 2038 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2039 rdomain == NULL ? "" : " rdomain \"", 2040 rdomain == NULL ? "" : rdomain, 2041 rdomain == NULL ? "" : "\""); 2042 free(laddr); 2043 2044 /* 2045 * We don't want to listen forever unless the other side 2046 * successfully authenticates itself. So we set up an alarm which is 2047 * cleared after successful authentication. A limit of zero 2048 * indicates no limit. Note that we don't set the alarm in debugging 2049 * mode; it is just annoying to have the server exit just when you 2050 * are about to discover the bug. 2051 */ 2052 ssh_signal(SIGALRM, grace_alarm_handler); 2053 if (!debug_flag) 2054 alarm(options.login_grace_time); 2055 2056 if ((r = kex_exchange_identification(ssh, -1, 2057 options.version_addendum)) != 0) 2058 sshpkt_fatal(ssh, r, "banner exchange"); 2059 2060 ssh_packet_set_nonblocking(ssh); 2061 2062 /* allocate authentication context */ 2063 authctxt = xcalloc(1, sizeof(*authctxt)); 2064 ssh->authctxt = authctxt; 2065 2066 /* XXX global for cleanup, access from other modules */ 2067 the_authctxt = authctxt; 2068 2069 /* Set default key authentication options */ 2070 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2071 fatal("allocation failed"); 2072 2073 /* prepare buffer to collect messages to display to user after login */ 2074 if ((loginmsg = sshbuf_new()) == NULL) 2075 fatal_f("sshbuf_new failed"); 2076 auth_debug_reset(); 2077 2078 if (use_privsep) { 2079 if (privsep_preauth(ssh) == 1) 2080 goto authenticated; 2081 } else if (have_agent) { 2082 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2083 error_r(r, "Unable to get agent socket"); 2084 have_agent = 0; 2085 } 2086 } 2087 2088 /* perform the key exchange */ 2089 /* authenticate user and start session */ 2090 do_ssh2_kex(ssh); 2091 do_authentication2(ssh); 2092 2093 /* 2094 * If we use privilege separation, the unprivileged child transfers 2095 * the current keystate and exits 2096 */ 2097 if (use_privsep) { 2098 mm_send_keystate(ssh, pmonitor); 2099 ssh_packet_clear_keys(ssh); 2100 exit(0); 2101 } 2102 2103 authenticated: 2104 /* 2105 * Cancel the alarm we set to limit the time taken for 2106 * authentication. 2107 */ 2108 alarm(0); 2109 ssh_signal(SIGALRM, SIG_DFL); 2110 authctxt->authenticated = 1; 2111 if (startup_pipe != -1) { 2112 close(startup_pipe); 2113 startup_pipe = -1; 2114 } 2115 2116 if (options.routing_domain != NULL) 2117 set_process_rdomain(ssh, options.routing_domain); 2118 2119 /* 2120 * In privilege separation, we fork another child and prepare 2121 * file descriptor passing. 2122 */ 2123 if (use_privsep) { 2124 privsep_postauth(ssh, authctxt); 2125 /* the monitor process [priv] will not return */ 2126 } 2127 2128 ssh_packet_set_timeout(ssh, options.client_alive_interval, 2129 options.client_alive_count_max); 2130 2131 /* Try to send all our hostkeys to the client */ 2132 notify_hostkeys(ssh); 2133 2134 /* Start session. */ 2135 do_authenticated(ssh, authctxt); 2136 2137 /* The connection has been terminated. */ 2138 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 2139 verbose("Transferred: sent %llu, received %llu bytes", 2140 (unsigned long long)obytes, (unsigned long long)ibytes); 2141 2142 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2143 ssh_packet_close(ssh); 2144 2145 if (use_privsep) 2146 mm_terminate(); 2147 2148 exit(0); 2149 } 2150 2151 int 2152 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 2153 struct sshkey *pubkey, u_char **signature, size_t *slenp, 2154 const u_char *data, size_t dlen, const char *alg) 2155 { 2156 int r; 2157 2158 if (use_privsep) { 2159 if (privkey) { 2160 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 2161 data, dlen, alg, options.sk_provider, NULL, 2162 ssh->compat) < 0) 2163 fatal_f("privkey sign failed"); 2164 } else { 2165 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 2166 data, dlen, alg, options.sk_provider, NULL, 2167 ssh->compat) < 0) 2168 fatal_f("pubkey sign failed"); 2169 } 2170 } else { 2171 if (privkey) { 2172 if (sshkey_sign(privkey, signature, slenp, data, dlen, 2173 alg, options.sk_provider, NULL, ssh->compat) < 0) 2174 fatal_f("privkey sign failed"); 2175 } else { 2176 if ((r = ssh_agent_sign(auth_sock, pubkey, 2177 signature, slenp, data, dlen, alg, 2178 ssh->compat)) != 0) { 2179 fatal_fr(r, "agent sign failed"); 2180 } 2181 } 2182 } 2183 return 0; 2184 } 2185 2186 /* SSH2 key exchange */ 2187 static void 2188 do_ssh2_kex(struct ssh *ssh) 2189 { 2190 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2191 struct kex *kex; 2192 int r; 2193 2194 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(ssh, 2195 options.kex_algorithms); 2196 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal(ssh, 2197 options.ciphers); 2198 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal(ssh, 2199 options.ciphers); 2200 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2201 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2202 2203 if (options.compression == COMP_NONE) { 2204 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2205 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2206 } 2207 2208 if (options.rekey_limit || options.rekey_interval) 2209 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 2210 options.rekey_interval); 2211 2212 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2213 ssh, list_hostkey_types()); 2214 2215 /* start key exchange */ 2216 if ((r = kex_setup(ssh, myproposal)) != 0) 2217 fatal_r(r, "kex_setup"); 2218 kex = ssh->kex; 2219 #ifdef WITH_OPENSSL 2220 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 2221 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 2222 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 2223 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 2224 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 2225 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2226 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2227 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 2228 #endif 2229 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 2230 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; 2231 kex->load_host_public_key=&get_hostkey_public_by_type; 2232 kex->load_host_private_key=&get_hostkey_private_by_type; 2233 kex->host_key_index=&get_hostkey_index; 2234 kex->sign = sshd_hostkey_sign; 2235 2236 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 2237 2238 #ifdef DEBUG_KEXDH 2239 /* send 1st encrypted/maced/compressed message */ 2240 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 2241 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 2242 (r = sshpkt_send(ssh)) != 0 || 2243 (r = ssh_packet_write_wait(ssh)) != 0) 2244 fatal_fr(r, "send test"); 2245 #endif 2246 debug("KEX done"); 2247 } 2248 2249 /* server specific fatal cleanup */ 2250 void 2251 cleanup_exit(int i) 2252 { 2253 if (the_active_state != NULL && the_authctxt != NULL) { 2254 do_cleanup(the_active_state, the_authctxt); 2255 if (use_privsep && privsep_is_preauth && 2256 pmonitor != NULL && pmonitor->m_pid > 1) { 2257 debug("Killing privsep child %d", pmonitor->m_pid); 2258 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2259 errno != ESRCH) { 2260 error_f("kill(%d): %s", pmonitor->m_pid, 2261 strerror(errno)); 2262 } 2263 } 2264 } 2265 _exit(i); 2266 } 2267