1 /* $OpenBSD: sshd.c,v 1.563 2020/10/16 13:26:13 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 <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 if (rexeced_flag) { 979 close(REEXEC_CONFIG_PASS_FD); 980 *sock_in = *sock_out = dup(STDIN_FILENO); 981 } else { 982 *sock_in = dup(STDIN_FILENO); 983 *sock_out = dup(STDOUT_FILENO); 984 } 985 /* 986 * We intentionally do not close the descriptors 0, 1, and 2 987 * as our code for setting the descriptors won't work if 988 * ttyfd happens to be one of those. 989 */ 990 if (stdfd_devnull(1, 1, !log_stderr) == -1) 991 error("%s: stdfd_devnull failed", __func__); 992 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 993 } 994 995 /* 996 * Listen for TCP connections 997 */ 998 static void 999 listen_on_addrs(struct listenaddr *la) 1000 { 1001 int ret, listen_sock; 1002 struct addrinfo *ai; 1003 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 1004 1005 for (ai = la->addrs; ai; ai = ai->ai_next) { 1006 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 1007 continue; 1008 if (num_listen_socks >= MAX_LISTEN_SOCKS) 1009 fatal("Too many listen sockets. " 1010 "Enlarge MAX_LISTEN_SOCKS"); 1011 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 1012 ntop, sizeof(ntop), strport, sizeof(strport), 1013 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 1014 error("getnameinfo failed: %.100s", 1015 ssh_gai_strerror(ret)); 1016 continue; 1017 } 1018 /* Create socket for listening. */ 1019 listen_sock = socket(ai->ai_family, ai->ai_socktype, 1020 ai->ai_protocol); 1021 if (listen_sock == -1) { 1022 /* kernel may not support ipv6 */ 1023 verbose("socket: %.100s", strerror(errno)); 1024 continue; 1025 } 1026 if (set_nonblock(listen_sock) == -1) { 1027 close(listen_sock); 1028 continue; 1029 } 1030 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1031 verbose("socket: CLOEXEC: %s", strerror(errno)); 1032 close(listen_sock); 1033 continue; 1034 } 1035 /* Socket options */ 1036 set_reuseaddr(listen_sock); 1037 if (la->rdomain != NULL && 1038 set_rdomain(listen_sock, la->rdomain) == -1) { 1039 close(listen_sock); 1040 continue; 1041 } 1042 1043 debug("Bind to port %s on %s.", strport, ntop); 1044 1045 /* Bind the socket to the desired port. */ 1046 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 1047 error("Bind to port %s on %s failed: %.200s.", 1048 strport, ntop, strerror(errno)); 1049 close(listen_sock); 1050 continue; 1051 } 1052 listen_socks[num_listen_socks] = listen_sock; 1053 num_listen_socks++; 1054 1055 /* Start listening on the port. */ 1056 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 1057 fatal("listen on [%s]:%s: %.100s", 1058 ntop, strport, strerror(errno)); 1059 logit("Server listening on %s port %s%s%s.", 1060 ntop, strport, 1061 la->rdomain == NULL ? "" : " rdomain ", 1062 la->rdomain == NULL ? "" : la->rdomain); 1063 } 1064 } 1065 1066 static void 1067 server_listen(void) 1068 { 1069 u_int i; 1070 1071 for (i = 0; i < options.num_listen_addrs; i++) { 1072 listen_on_addrs(&options.listen_addrs[i]); 1073 freeaddrinfo(options.listen_addrs[i].addrs); 1074 free(options.listen_addrs[i].rdomain); 1075 memset(&options.listen_addrs[i], 0, 1076 sizeof(options.listen_addrs[i])); 1077 } 1078 free(options.listen_addrs); 1079 options.listen_addrs = NULL; 1080 options.num_listen_addrs = 0; 1081 1082 if (!num_listen_socks) 1083 fatal("Cannot bind any address."); 1084 } 1085 1086 /* 1087 * The main TCP accept loop. Note that, for the non-debug case, returns 1088 * from this function are in a forked subprocess. 1089 */ 1090 static void 1091 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1092 { 1093 fd_set *fdset; 1094 int i, j, ret, maxfd; 1095 int ostartups = -1, startups = 0, listening = 0, lameduck = 0; 1096 int startup_p[2] = { -1 , -1 }; 1097 char c = 0; 1098 struct sockaddr_storage from; 1099 socklen_t fromlen; 1100 pid_t pid; 1101 1102 /* setup fd set for accept */ 1103 fdset = NULL; 1104 maxfd = 0; 1105 for (i = 0; i < num_listen_socks; i++) 1106 if (listen_socks[i] > maxfd) 1107 maxfd = listen_socks[i]; 1108 /* pipes connected to unauthenticated child sshd processes */ 1109 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1110 startup_flags = xcalloc(options.max_startups, sizeof(int)); 1111 for (i = 0; i < options.max_startups; i++) 1112 startup_pipes[i] = -1; 1113 1114 /* 1115 * Stay listening for connections until the system crashes or 1116 * the daemon is killed with a signal. 1117 */ 1118 for (;;) { 1119 if (ostartups != startups) { 1120 setproctitle("%s [listener] %d of %d-%d startups", 1121 listener_proctitle, startups, 1122 options.max_startups_begin, options.max_startups); 1123 ostartups = startups; 1124 } 1125 if (received_sighup) { 1126 if (!lameduck) { 1127 debug("Received SIGHUP; waiting for children"); 1128 close_listen_socks(); 1129 lameduck = 1; 1130 } 1131 if (listening <= 0) 1132 sighup_restart(); 1133 } 1134 free(fdset); 1135 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1136 sizeof(fd_mask)); 1137 1138 for (i = 0; i < num_listen_socks; i++) 1139 FD_SET(listen_socks[i], fdset); 1140 for (i = 0; i < options.max_startups; i++) 1141 if (startup_pipes[i] != -1) 1142 FD_SET(startup_pipes[i], fdset); 1143 1144 /* Wait in select until there is a connection. */ 1145 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1146 if (ret == -1 && errno != EINTR) 1147 error("select: %.100s", strerror(errno)); 1148 if (received_sigterm) { 1149 logit("Received signal %d; terminating.", 1150 (int) received_sigterm); 1151 close_listen_socks(); 1152 if (options.pid_file != NULL) 1153 unlink(options.pid_file); 1154 exit(received_sigterm == SIGTERM ? 0 : 255); 1155 } 1156 if (ret == -1) 1157 continue; 1158 1159 for (i = 0; i < options.max_startups; i++) { 1160 if (startup_pipes[i] == -1 || 1161 !FD_ISSET(startup_pipes[i], fdset)) 1162 continue; 1163 switch (read(startup_pipes[i], &c, sizeof(c))) { 1164 case -1: 1165 if (errno == EINTR || errno == EAGAIN) 1166 continue; 1167 if (errno != EPIPE) { 1168 error("%s: startup pipe %d (fd=%d): " 1169 "read %s", __func__, i, 1170 startup_pipes[i], strerror(errno)); 1171 } 1172 /* FALLTHROUGH */ 1173 case 0: 1174 /* child exited or completed auth */ 1175 close(startup_pipes[i]); 1176 startup_pipes[i] = -1; 1177 startups--; 1178 if (startup_flags[i]) 1179 listening--; 1180 break; 1181 case 1: 1182 /* child has finished preliminaries */ 1183 if (startup_flags[i]) { 1184 listening--; 1185 startup_flags[i] = 0; 1186 } 1187 break; 1188 } 1189 } 1190 for (i = 0; i < num_listen_socks; i++) { 1191 if (!FD_ISSET(listen_socks[i], fdset)) 1192 continue; 1193 fromlen = sizeof(from); 1194 *newsock = accept(listen_socks[i], 1195 (struct sockaddr *)&from, &fromlen); 1196 if (*newsock == -1) { 1197 if (errno != EINTR && errno != EWOULDBLOCK && 1198 errno != ECONNABORTED) 1199 error("accept: %.100s", 1200 strerror(errno)); 1201 if (errno == EMFILE || errno == ENFILE) 1202 usleep(100 * 1000); 1203 continue; 1204 } 1205 if (unset_nonblock(*newsock) == -1 || 1206 drop_connection(*newsock, startups) || 1207 pipe(startup_p) == -1) { 1208 close(*newsock); 1209 continue; 1210 } 1211 1212 if (rexec_flag && socketpair(AF_UNIX, 1213 SOCK_STREAM, 0, config_s) == -1) { 1214 error("reexec socketpair: %s", 1215 strerror(errno)); 1216 close(*newsock); 1217 close(startup_p[0]); 1218 close(startup_p[1]); 1219 continue; 1220 } 1221 1222 for (j = 0; j < options.max_startups; j++) 1223 if (startup_pipes[j] == -1) { 1224 startup_pipes[j] = startup_p[0]; 1225 if (maxfd < startup_p[0]) 1226 maxfd = startup_p[0]; 1227 startups++; 1228 startup_flags[j] = 1; 1229 break; 1230 } 1231 1232 /* 1233 * Got connection. Fork a child to handle it, unless 1234 * we are in debugging mode. 1235 */ 1236 if (debug_flag) { 1237 /* 1238 * In debugging mode. Close the listening 1239 * socket, and start processing the 1240 * connection without forking. 1241 */ 1242 debug("Server will not fork when running in debugging mode."); 1243 close_listen_socks(); 1244 *sock_in = *newsock; 1245 *sock_out = *newsock; 1246 close(startup_p[0]); 1247 close(startup_p[1]); 1248 startup_pipe = -1; 1249 pid = getpid(); 1250 if (rexec_flag) { 1251 send_rexec_state(config_s[0], cfg); 1252 close(config_s[0]); 1253 } 1254 return; 1255 } 1256 1257 /* 1258 * Normal production daemon. Fork, and have 1259 * the child process the connection. The 1260 * parent continues listening. 1261 */ 1262 listening++; 1263 if ((pid = fork()) == 0) { 1264 /* 1265 * Child. Close the listening and 1266 * max_startup sockets. Start using 1267 * the accepted socket. Reinitialize 1268 * logging (since our pid has changed). 1269 * We return from this function to handle 1270 * the connection. 1271 */ 1272 startup_pipe = startup_p[1]; 1273 close_startup_pipes(); 1274 close_listen_socks(); 1275 *sock_in = *newsock; 1276 *sock_out = *newsock; 1277 log_init(__progname, 1278 options.log_level, 1279 options.log_facility, 1280 log_stderr); 1281 if (rexec_flag) 1282 close(config_s[0]); 1283 else { 1284 /* 1285 * Signal parent that the preliminaries 1286 * for this child are complete. For the 1287 * re-exec case, this happens after the 1288 * child has received the rexec state 1289 * from the server. 1290 */ 1291 (void)atomicio(vwrite, startup_pipe, 1292 "\0", 1); 1293 } 1294 return; 1295 } 1296 1297 /* Parent. Stay in the loop. */ 1298 if (pid == -1) 1299 error("fork: %.100s", strerror(errno)); 1300 else 1301 debug("Forked child %ld.", (long)pid); 1302 1303 close(startup_p[1]); 1304 1305 if (rexec_flag) { 1306 close(config_s[1]); 1307 send_rexec_state(config_s[0], cfg); 1308 close(config_s[0]); 1309 } 1310 close(*newsock); 1311 } 1312 } 1313 } 1314 1315 /* 1316 * If IP options are supported, make sure there are none (log and 1317 * return an error if any are found). Basically we are worried about 1318 * source routing; it can be used to pretend you are somebody 1319 * (ip-address) you are not. That itself may be "almost acceptable" 1320 * under certain circumstances, but rhosts authentication is useless 1321 * if source routing is accepted. Notice also that if we just dropped 1322 * source routing here, the other side could use IP spoofing to do 1323 * rest of the interaction and could still bypass security. So we 1324 * exit here if we detect any IP options. 1325 */ 1326 static void 1327 check_ip_options(struct ssh *ssh) 1328 { 1329 int sock_in = ssh_packet_get_connection_in(ssh); 1330 struct sockaddr_storage from; 1331 u_char opts[200]; 1332 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1333 char text[sizeof(opts) * 3 + 1]; 1334 1335 memset(&from, 0, sizeof(from)); 1336 if (getpeername(sock_in, (struct sockaddr *)&from, 1337 &fromlen) == -1) 1338 return; 1339 if (from.ss_family != AF_INET) 1340 return; 1341 /* XXX IPv6 options? */ 1342 1343 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1344 &option_size) >= 0 && option_size != 0) { 1345 text[0] = '\0'; 1346 for (i = 0; i < option_size; i++) 1347 snprintf(text + i*3, sizeof(text) - i*3, 1348 " %2.2x", opts[i]); 1349 fatal("Connection from %.100s port %d with IP opts: %.800s", 1350 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1351 } 1352 return; 1353 } 1354 1355 /* Set the routing domain for this process */ 1356 static void 1357 set_process_rdomain(struct ssh *ssh, const char *name) 1358 { 1359 int rtable, ortable = getrtable(); 1360 const char *errstr; 1361 1362 if (name == NULL) 1363 return; /* default */ 1364 1365 if (strcmp(name, "%D") == 0) { 1366 /* "expands" to routing domain of connection */ 1367 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1368 return; 1369 } 1370 1371 rtable = (int)strtonum(name, 0, 255, &errstr); 1372 if (errstr != NULL) /* Shouldn't happen */ 1373 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1374 if (rtable != ortable && setrtable(rtable) != 0) 1375 fatal("Unable to set routing domain %d: %s", 1376 rtable, strerror(errno)); 1377 debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable); 1378 } 1379 1380 static void 1381 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1382 struct sshkey *key) 1383 { 1384 static struct ssh_digest_ctx *ctx; 1385 u_char *hash; 1386 size_t len; 1387 struct sshbuf *buf; 1388 int r; 1389 1390 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1391 fatal("%s: ssh_digest_start", __func__); 1392 if (key == NULL) { /* finalize */ 1393 /* add server config in case we are using agent for host keys */ 1394 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1395 sshbuf_len(server_cfg)) != 0) 1396 fatal("%s: ssh_digest_update", __func__); 1397 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1398 hash = xmalloc(len); 1399 if (ssh_digest_final(ctx, hash, len) != 0) 1400 fatal("%s: ssh_digest_final", __func__); 1401 options.timing_secret = PEEK_U64(hash); 1402 freezero(hash, len); 1403 ssh_digest_free(ctx); 1404 ctx = NULL; 1405 return; 1406 } 1407 if ((buf = sshbuf_new()) == NULL) 1408 fatal("%s could not allocate buffer", __func__); 1409 if ((r = sshkey_private_serialize(key, buf)) != 0) 1410 fatal("sshkey_private_serialize: %s", ssh_err(r)); 1411 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1412 fatal("%s: ssh_digest_update", __func__); 1413 sshbuf_reset(buf); 1414 sshbuf_free(buf); 1415 } 1416 1417 static char * 1418 prepare_proctitle(int ac, char **av) 1419 { 1420 char *ret = NULL; 1421 int i; 1422 1423 for (i = 0; i < ac; i++) 1424 xextendf(&ret, " ", "%s", av[i]); 1425 return ret; 1426 } 1427 1428 /* 1429 * Main program for the daemon. 1430 */ 1431 int 1432 main(int ac, char **av) 1433 { 1434 struct ssh *ssh = NULL; 1435 extern char *optarg; 1436 extern int optind; 1437 int r, opt, on = 1, already_daemon, remote_port; 1438 int sock_in = -1, sock_out = -1, newsock = -1; 1439 const char *remote_ip, *rdomain; 1440 char *fp, *line, *laddr, *logfile = NULL; 1441 int config_s[2] = { -1 , -1 }; 1442 u_int i, j; 1443 u_int64_t ibytes, obytes; 1444 mode_t new_umask; 1445 struct sshkey *key; 1446 struct sshkey *pubkey; 1447 int keytype; 1448 Authctxt *authctxt; 1449 struct connection_info *connection_info = NULL; 1450 1451 /* Save argv. */ 1452 saved_argv = av; 1453 rexec_argc = ac; 1454 1455 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1456 sanitise_stdfd(); 1457 1458 /* Initialize configuration options to their default values. */ 1459 initialize_server_options(&options); 1460 1461 /* Parse command-line arguments. */ 1462 while ((opt = getopt(ac, av, 1463 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1464 switch (opt) { 1465 case '4': 1466 options.address_family = AF_INET; 1467 break; 1468 case '6': 1469 options.address_family = AF_INET6; 1470 break; 1471 case 'f': 1472 config_file_name = optarg; 1473 break; 1474 case 'c': 1475 servconf_add_hostcert("[command-line]", 0, 1476 &options, optarg); 1477 break; 1478 case 'd': 1479 if (debug_flag == 0) { 1480 debug_flag = 1; 1481 options.log_level = SYSLOG_LEVEL_DEBUG1; 1482 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1483 options.log_level++; 1484 break; 1485 case 'D': 1486 no_daemon_flag = 1; 1487 break; 1488 case 'E': 1489 logfile = optarg; 1490 /* FALLTHROUGH */ 1491 case 'e': 1492 log_stderr = 1; 1493 break; 1494 case 'i': 1495 inetd_flag = 1; 1496 break; 1497 case 'r': 1498 rexec_flag = 0; 1499 break; 1500 case 'R': 1501 rexeced_flag = 1; 1502 inetd_flag = 1; 1503 break; 1504 case 'Q': 1505 /* ignored */ 1506 break; 1507 case 'q': 1508 options.log_level = SYSLOG_LEVEL_QUIET; 1509 break; 1510 case 'b': 1511 /* protocol 1, ignored */ 1512 break; 1513 case 'p': 1514 options.ports_from_cmdline = 1; 1515 if (options.num_ports >= MAX_PORTS) { 1516 fprintf(stderr, "too many ports.\n"); 1517 exit(1); 1518 } 1519 options.ports[options.num_ports++] = a2port(optarg); 1520 if (options.ports[options.num_ports-1] <= 0) { 1521 fprintf(stderr, "Bad port number.\n"); 1522 exit(1); 1523 } 1524 break; 1525 case 'g': 1526 if ((options.login_grace_time = convtime(optarg)) == -1) { 1527 fprintf(stderr, "Invalid login grace time.\n"); 1528 exit(1); 1529 } 1530 break; 1531 case 'k': 1532 /* protocol 1, ignored */ 1533 break; 1534 case 'h': 1535 servconf_add_hostkey("[command-line]", 0, 1536 &options, optarg, 1); 1537 break; 1538 case 't': 1539 test_flag = 1; 1540 break; 1541 case 'T': 1542 test_flag = 2; 1543 break; 1544 case 'C': 1545 connection_info = get_connection_info(ssh, 0, 0); 1546 if (parse_server_match_testspec(connection_info, 1547 optarg) == -1) 1548 exit(1); 1549 break; 1550 case 'u': 1551 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1552 if (utmp_len > HOST_NAME_MAX+1) { 1553 fprintf(stderr, "Invalid utmp length.\n"); 1554 exit(1); 1555 } 1556 break; 1557 case 'o': 1558 line = xstrdup(optarg); 1559 if (process_server_config_line(&options, line, 1560 "command-line", 0, NULL, NULL, &includes) != 0) 1561 exit(1); 1562 free(line); 1563 break; 1564 case '?': 1565 default: 1566 usage(); 1567 break; 1568 } 1569 } 1570 if (rexeced_flag || inetd_flag) 1571 rexec_flag = 0; 1572 if (!test_flag && rexec_flag && !path_absolute(av[0])) 1573 fatal("sshd re-exec requires execution with an absolute path"); 1574 if (rexeced_flag) 1575 closefrom(REEXEC_MIN_FREE_FD); 1576 else 1577 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1578 1579 #ifdef WITH_OPENSSL 1580 OpenSSL_add_all_algorithms(); 1581 #endif 1582 1583 /* If requested, redirect the logs to the specified logfile. */ 1584 if (logfile != NULL) 1585 log_redirect_stderr_to(logfile); 1586 /* 1587 * Force logging to stderr until we have loaded the private host 1588 * key (unless started from inetd) 1589 */ 1590 log_init(__progname, 1591 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1592 SYSLOG_LEVEL_INFO : options.log_level, 1593 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1594 SYSLOG_FACILITY_AUTH : options.log_facility, 1595 log_stderr || !inetd_flag || debug_flag); 1596 1597 sensitive_data.have_ssh2_key = 0; 1598 1599 /* 1600 * If we're not doing an extended test do not silently ignore connection 1601 * test params. 1602 */ 1603 if (test_flag < 2 && connection_info != NULL) 1604 fatal("Config test connection parameter (-C) provided without " 1605 "test mode (-T)"); 1606 1607 /* Fetch our configuration */ 1608 if ((cfg = sshbuf_new()) == NULL) 1609 fatal("%s: sshbuf_new failed", __func__); 1610 if (rexeced_flag) { 1611 setproctitle("%s", "[rexeced]"); 1612 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1613 if (!debug_flag) { 1614 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1615 close(REEXEC_STARTUP_PIPE_FD); 1616 /* 1617 * Signal parent that this child is at a point where 1618 * they can go away if they have a SIGHUP pending. 1619 */ 1620 (void)atomicio(vwrite, startup_pipe, "\0", 1); 1621 } 1622 } else if (strcasecmp(config_file_name, "none") != 0) 1623 load_server_config(config_file_name, cfg); 1624 1625 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1626 cfg, &includes, NULL); 1627 1628 /* Fill in default values for those options not explicitly set. */ 1629 fill_default_server_options(&options); 1630 1631 /* challenge-response is implemented via keyboard interactive */ 1632 if (options.challenge_response_authentication) 1633 options.kbd_interactive_authentication = 1; 1634 1635 /* Check that options are sensible */ 1636 if (options.authorized_keys_command_user == NULL && 1637 (options.authorized_keys_command != NULL && 1638 strcasecmp(options.authorized_keys_command, "none") != 0)) 1639 fatal("AuthorizedKeysCommand set without " 1640 "AuthorizedKeysCommandUser"); 1641 if (options.authorized_principals_command_user == NULL && 1642 (options.authorized_principals_command != NULL && 1643 strcasecmp(options.authorized_principals_command, "none") != 0)) 1644 fatal("AuthorizedPrincipalsCommand set without " 1645 "AuthorizedPrincipalsCommandUser"); 1646 1647 /* 1648 * Check whether there is any path through configured auth methods. 1649 * Unfortunately it is not possible to verify this generally before 1650 * daemonisation in the presence of Match block, but this catches 1651 * and warns for trivial misconfigurations that could break login. 1652 */ 1653 if (options.num_auth_methods != 0) { 1654 for (i = 0; i < options.num_auth_methods; i++) { 1655 if (auth2_methods_valid(options.auth_methods[i], 1656 1) == 0) 1657 break; 1658 } 1659 if (i >= options.num_auth_methods) 1660 fatal("AuthenticationMethods cannot be satisfied by " 1661 "enabled authentication methods"); 1662 } 1663 1664 /* Check that there are no remaining arguments. */ 1665 if (optind < ac) { 1666 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1667 exit(1); 1668 } 1669 1670 debug("sshd version %s, %s", SSH_VERSION, 1671 #ifdef WITH_OPENSSL 1672 OpenSSL_version(OPENSSL_VERSION) 1673 #else 1674 "without OpenSSL" 1675 #endif 1676 ); 1677 1678 /* load host keys */ 1679 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1680 sizeof(struct sshkey *)); 1681 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1682 sizeof(struct sshkey *)); 1683 1684 if (options.host_key_agent) { 1685 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1686 setenv(SSH_AUTHSOCKET_ENV_NAME, 1687 options.host_key_agent, 1); 1688 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1689 have_agent = 1; 1690 else 1691 error("Could not connect to agent \"%s\": %s", 1692 options.host_key_agent, ssh_err(r)); 1693 } 1694 1695 for (i = 0; i < options.num_host_key_files; i++) { 1696 int ll = options.host_key_file_userprovided[i] ? 1697 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1698 1699 if (options.host_key_files[i] == NULL) 1700 continue; 1701 if ((r = sshkey_load_private(options.host_key_files[i], "", 1702 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1703 do_log2(ll, "Unable to load host key \"%s\": %s", 1704 options.host_key_files[i], ssh_err(r)); 1705 if (sshkey_is_sk(key) && 1706 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1707 debug("host key %s requires user presence, ignoring", 1708 options.host_key_files[i]); 1709 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1710 } 1711 if (r == 0 && key != NULL && 1712 (r = sshkey_shield_private(key)) != 0) { 1713 do_log2(ll, "Unable to shield host key \"%s\": %s", 1714 options.host_key_files[i], ssh_err(r)); 1715 sshkey_free(key); 1716 key = NULL; 1717 } 1718 if ((r = sshkey_load_public(options.host_key_files[i], 1719 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1720 do_log2(ll, "Unable to load host key \"%s\": %s", 1721 options.host_key_files[i], ssh_err(r)); 1722 if (pubkey != NULL && key != NULL) { 1723 if (!sshkey_equal(pubkey, key)) { 1724 error("Public key for %s does not match " 1725 "private key", options.host_key_files[i]); 1726 sshkey_free(pubkey); 1727 pubkey = NULL; 1728 } 1729 } 1730 if (pubkey == NULL && key != NULL) { 1731 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1732 fatal("Could not demote key: \"%s\": %s", 1733 options.host_key_files[i], ssh_err(r)); 1734 } 1735 sensitive_data.host_keys[i] = key; 1736 sensitive_data.host_pubkeys[i] = pubkey; 1737 1738 if (key == NULL && pubkey != NULL && have_agent) { 1739 debug("will rely on agent for hostkey %s", 1740 options.host_key_files[i]); 1741 keytype = pubkey->type; 1742 } else if (key != NULL) { 1743 keytype = key->type; 1744 accumulate_host_timing_secret(cfg, key); 1745 } else { 1746 do_log2(ll, "Unable to load host key: %s", 1747 options.host_key_files[i]); 1748 sensitive_data.host_keys[i] = NULL; 1749 sensitive_data.host_pubkeys[i] = NULL; 1750 continue; 1751 } 1752 1753 switch (keytype) { 1754 case KEY_RSA: 1755 case KEY_DSA: 1756 case KEY_ECDSA: 1757 case KEY_ED25519: 1758 case KEY_ECDSA_SK: 1759 case KEY_ED25519_SK: 1760 case KEY_XMSS: 1761 if (have_agent || key != NULL) 1762 sensitive_data.have_ssh2_key = 1; 1763 break; 1764 } 1765 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1766 SSH_FP_DEFAULT)) == NULL) 1767 fatal("sshkey_fingerprint failed"); 1768 debug("%s host key #%d: %s %s", 1769 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1770 free(fp); 1771 } 1772 accumulate_host_timing_secret(cfg, NULL); 1773 if (!sensitive_data.have_ssh2_key) { 1774 logit("sshd: no hostkeys available -- exiting."); 1775 exit(1); 1776 } 1777 1778 /* 1779 * Load certificates. They are stored in an array at identical 1780 * indices to the public keys that they relate to. 1781 */ 1782 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1783 sizeof(struct sshkey *)); 1784 for (i = 0; i < options.num_host_key_files; i++) 1785 sensitive_data.host_certificates[i] = NULL; 1786 1787 for (i = 0; i < options.num_host_cert_files; i++) { 1788 if (options.host_cert_files[i] == NULL) 1789 continue; 1790 if ((r = sshkey_load_public(options.host_cert_files[i], 1791 &key, NULL)) != 0) { 1792 error("Could not load host certificate \"%s\": %s", 1793 options.host_cert_files[i], ssh_err(r)); 1794 continue; 1795 } 1796 if (!sshkey_is_cert(key)) { 1797 error("Certificate file is not a certificate: %s", 1798 options.host_cert_files[i]); 1799 sshkey_free(key); 1800 continue; 1801 } 1802 /* Find matching private key */ 1803 for (j = 0; j < options.num_host_key_files; j++) { 1804 if (sshkey_equal_public(key, 1805 sensitive_data.host_keys[j])) { 1806 sensitive_data.host_certificates[j] = key; 1807 break; 1808 } 1809 } 1810 if (j >= options.num_host_key_files) { 1811 error("No matching private key for certificate: %s", 1812 options.host_cert_files[i]); 1813 sshkey_free(key); 1814 continue; 1815 } 1816 sensitive_data.host_certificates[j] = key; 1817 debug("host certificate: #%u type %d %s", j, key->type, 1818 sshkey_type(key)); 1819 } 1820 1821 if (use_privsep) { 1822 struct stat st; 1823 1824 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1825 fatal("Privilege separation user %s does not exist", 1826 SSH_PRIVSEP_USER); 1827 endpwent(); 1828 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1829 (S_ISDIR(st.st_mode) == 0)) 1830 fatal("Missing privilege separation directory: %s", 1831 _PATH_PRIVSEP_CHROOT_DIR); 1832 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1833 fatal("%s must be owned by root and not group or " 1834 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1835 } 1836 1837 if (test_flag > 1) { 1838 /* 1839 * If no connection info was provided by -C then use 1840 * use a blank one that will cause no predicate to match. 1841 */ 1842 if (connection_info == NULL) 1843 connection_info = get_connection_info(ssh, 0, 0); 1844 connection_info->test = 1; 1845 parse_server_match_config(&options, &includes, connection_info); 1846 dump_config(&options); 1847 } 1848 1849 /* Configuration looks good, so exit if in test mode. */ 1850 if (test_flag) 1851 exit(0); 1852 1853 if (rexec_flag) { 1854 if (rexec_argc < 0) 1855 fatal("rexec_argc %d < 0", rexec_argc); 1856 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1857 for (i = 0; i < (u_int)rexec_argc; i++) { 1858 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1859 rexec_argv[i] = saved_argv[i]; 1860 } 1861 rexec_argv[rexec_argc] = "-R"; 1862 rexec_argv[rexec_argc + 1] = NULL; 1863 } 1864 listener_proctitle = prepare_proctitle(ac, av); 1865 1866 /* Ensure that umask disallows at least group and world write */ 1867 new_umask = umask(0077) | 0022; 1868 (void) umask(new_umask); 1869 1870 /* Initialize the log (it is reinitialized below in case we forked). */ 1871 if (debug_flag && (!inetd_flag || rexeced_flag)) 1872 log_stderr = 1; 1873 log_init(__progname, options.log_level, 1874 options.log_facility, log_stderr); 1875 for (i = 0; i < options.num_log_verbose; i++) 1876 log_verbose_add(options.log_verbose[i]); 1877 1878 /* 1879 * If not in debugging mode, not started from inetd and not already 1880 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1881 * terminal, and fork. The original process exits. 1882 */ 1883 already_daemon = daemonized(); 1884 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1885 1886 if (daemon(0, 0) == -1) 1887 fatal("daemon() failed: %.200s", strerror(errno)); 1888 1889 disconnect_controlling_tty(); 1890 } 1891 /* Reinitialize the log (because of the fork above). */ 1892 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1893 1894 /* Chdir to the root directory so that the current disk can be 1895 unmounted if desired. */ 1896 if (chdir("/") == -1) 1897 error("chdir(\"/\"): %s", strerror(errno)); 1898 1899 /* ignore SIGPIPE */ 1900 ssh_signal(SIGPIPE, SIG_IGN); 1901 1902 /* Get a connection, either from inetd or a listening TCP socket */ 1903 if (inetd_flag) { 1904 server_accept_inetd(&sock_in, &sock_out); 1905 } else { 1906 server_listen(); 1907 1908 ssh_signal(SIGHUP, sighup_handler); 1909 ssh_signal(SIGCHLD, main_sigchld_handler); 1910 ssh_signal(SIGTERM, sigterm_handler); 1911 ssh_signal(SIGQUIT, sigterm_handler); 1912 1913 /* 1914 * Write out the pid file after the sigterm handler 1915 * is setup and the listen sockets are bound 1916 */ 1917 if (options.pid_file != NULL && !debug_flag) { 1918 FILE *f = fopen(options.pid_file, "w"); 1919 1920 if (f == NULL) { 1921 error("Couldn't create pid file \"%s\": %s", 1922 options.pid_file, strerror(errno)); 1923 } else { 1924 fprintf(f, "%ld\n", (long) getpid()); 1925 fclose(f); 1926 } 1927 } 1928 1929 /* Accept a connection and return in a forked child */ 1930 server_accept_loop(&sock_in, &sock_out, 1931 &newsock, config_s); 1932 } 1933 1934 /* This is the child processing a new connection. */ 1935 setproctitle("%s", "[accepted]"); 1936 1937 /* 1938 * Create a new session and process group since the 4.4BSD 1939 * setlogin() affects the entire process group. We don't 1940 * want the child to be able to affect the parent. 1941 */ 1942 if (!debug_flag && !inetd_flag && setsid() == -1) 1943 error("setsid: %.100s", strerror(errno)); 1944 1945 if (rexec_flag) { 1946 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1947 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1948 dup2(newsock, STDIN_FILENO); 1949 dup2(STDIN_FILENO, STDOUT_FILENO); 1950 if (startup_pipe == -1) 1951 close(REEXEC_STARTUP_PIPE_FD); 1952 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1953 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1954 close(startup_pipe); 1955 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1956 } 1957 1958 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1959 close(config_s[1]); 1960 1961 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 1962 execv(rexec_argv[0], rexec_argv); 1963 1964 /* Reexec has failed, fall back and continue */ 1965 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1966 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1967 log_init(__progname, options.log_level, 1968 options.log_facility, log_stderr); 1969 1970 /* Clean up fds */ 1971 close(REEXEC_CONFIG_PASS_FD); 1972 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1973 if (stdfd_devnull(1, 1, 0) == -1) 1974 error("%s: stdfd_devnull failed", __func__); 1975 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1976 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1977 } 1978 1979 /* Executed child processes don't need these. */ 1980 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1981 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1982 1983 /* We will not restart on SIGHUP since it no longer makes sense. */ 1984 ssh_signal(SIGALRM, SIG_DFL); 1985 ssh_signal(SIGHUP, SIG_DFL); 1986 ssh_signal(SIGTERM, SIG_DFL); 1987 ssh_signal(SIGQUIT, SIG_DFL); 1988 ssh_signal(SIGCHLD, SIG_DFL); 1989 1990 /* 1991 * Register our connection. This turns encryption off because we do 1992 * not have a key. 1993 */ 1994 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 1995 fatal("Unable to create connection"); 1996 the_active_state = ssh; 1997 ssh_packet_set_server(ssh); 1998 1999 check_ip_options(ssh); 2000 2001 /* Prepare the channels layer */ 2002 channel_init_channels(ssh); 2003 channel_set_af(ssh, options.address_family); 2004 process_permitopen(ssh, &options); 2005 2006 /* Set SO_KEEPALIVE if requested. */ 2007 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 2008 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) 2009 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2010 2011 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2012 debug("ssh_remote_port failed"); 2013 cleanup_exit(255); 2014 } 2015 2016 /* 2017 * The rest of the code depends on the fact that 2018 * ssh_remote_ipaddr() caches the remote ip, even if 2019 * the socket goes away. 2020 */ 2021 remote_ip = ssh_remote_ipaddr(ssh); 2022 2023 rdomain = ssh_packet_rdomain_in(ssh); 2024 2025 /* Log the connection. */ 2026 laddr = get_local_ipaddr(sock_in); 2027 verbose("Connection from %s port %d on %s port %d%s%s%s", 2028 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2029 rdomain == NULL ? "" : " rdomain \"", 2030 rdomain == NULL ? "" : rdomain, 2031 rdomain == NULL ? "" : "\""); 2032 free(laddr); 2033 2034 /* 2035 * We don't want to listen forever unless the other side 2036 * successfully authenticates itself. So we set up an alarm which is 2037 * cleared after successful authentication. A limit of zero 2038 * indicates no limit. Note that we don't set the alarm in debugging 2039 * mode; it is just annoying to have the server exit just when you 2040 * are about to discover the bug. 2041 */ 2042 ssh_signal(SIGALRM, grace_alarm_handler); 2043 if (!debug_flag) 2044 alarm(options.login_grace_time); 2045 2046 if ((r = kex_exchange_identification(ssh, -1, 2047 options.version_addendum)) != 0) 2048 sshpkt_fatal(ssh, r, "banner exchange"); 2049 2050 ssh_packet_set_nonblocking(ssh); 2051 2052 /* allocate authentication context */ 2053 authctxt = xcalloc(1, sizeof(*authctxt)); 2054 ssh->authctxt = authctxt; 2055 2056 /* XXX global for cleanup, access from other modules */ 2057 the_authctxt = authctxt; 2058 2059 /* Set default key authentication options */ 2060 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2061 fatal("allocation failed"); 2062 2063 /* prepare buffer to collect messages to display to user after login */ 2064 if ((loginmsg = sshbuf_new()) == NULL) 2065 fatal("%s: sshbuf_new failed", __func__); 2066 auth_debug_reset(); 2067 2068 if (use_privsep) { 2069 if (privsep_preauth(ssh) == 1) 2070 goto authenticated; 2071 } else if (have_agent) { 2072 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2073 error("Unable to get agent socket: %s", ssh_err(r)); 2074 have_agent = 0; 2075 } 2076 } 2077 2078 /* perform the key exchange */ 2079 /* authenticate user and start session */ 2080 do_ssh2_kex(ssh); 2081 do_authentication2(ssh); 2082 2083 /* 2084 * If we use privilege separation, the unprivileged child transfers 2085 * the current keystate and exits 2086 */ 2087 if (use_privsep) { 2088 mm_send_keystate(ssh, pmonitor); 2089 ssh_packet_clear_keys(ssh); 2090 exit(0); 2091 } 2092 2093 authenticated: 2094 /* 2095 * Cancel the alarm we set to limit the time taken for 2096 * authentication. 2097 */ 2098 alarm(0); 2099 ssh_signal(SIGALRM, SIG_DFL); 2100 authctxt->authenticated = 1; 2101 if (startup_pipe != -1) { 2102 close(startup_pipe); 2103 startup_pipe = -1; 2104 } 2105 2106 if (options.routing_domain != NULL) 2107 set_process_rdomain(ssh, options.routing_domain); 2108 2109 /* 2110 * In privilege separation, we fork another child and prepare 2111 * file descriptor passing. 2112 */ 2113 if (use_privsep) { 2114 privsep_postauth(ssh, authctxt); 2115 /* the monitor process [priv] will not return */ 2116 } 2117 2118 ssh_packet_set_timeout(ssh, options.client_alive_interval, 2119 options.client_alive_count_max); 2120 2121 /* Try to send all our hostkeys to the client */ 2122 notify_hostkeys(ssh); 2123 2124 /* Start session. */ 2125 do_authenticated(ssh, authctxt); 2126 2127 /* The connection has been terminated. */ 2128 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 2129 verbose("Transferred: sent %llu, received %llu bytes", 2130 (unsigned long long)obytes, (unsigned long long)ibytes); 2131 2132 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2133 ssh_packet_close(ssh); 2134 2135 if (use_privsep) 2136 mm_terminate(); 2137 2138 exit(0); 2139 } 2140 2141 int 2142 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 2143 struct sshkey *pubkey, u_char **signature, size_t *slenp, 2144 const u_char *data, size_t dlen, const char *alg) 2145 { 2146 int r; 2147 2148 if (use_privsep) { 2149 if (privkey) { 2150 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 2151 data, dlen, alg, options.sk_provider, NULL, 2152 ssh->compat) < 0) 2153 fatal("%s: privkey sign failed", __func__); 2154 } else { 2155 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 2156 data, dlen, alg, options.sk_provider, NULL, 2157 ssh->compat) < 0) 2158 fatal("%s: pubkey sign failed", __func__); 2159 } 2160 } else { 2161 if (privkey) { 2162 if (sshkey_sign(privkey, signature, slenp, data, dlen, 2163 alg, options.sk_provider, NULL, ssh->compat) < 0) 2164 fatal("%s: privkey sign failed", __func__); 2165 } else { 2166 if ((r = ssh_agent_sign(auth_sock, pubkey, 2167 signature, slenp, data, dlen, alg, 2168 ssh->compat)) != 0) { 2169 fatal("%s: agent sign failed: %s", 2170 __func__, ssh_err(r)); 2171 } 2172 } 2173 } 2174 return 0; 2175 } 2176 2177 /* SSH2 key exchange */ 2178 static void 2179 do_ssh2_kex(struct ssh *ssh) 2180 { 2181 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2182 struct kex *kex; 2183 int r; 2184 2185 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2186 options.kex_algorithms); 2187 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2188 options.ciphers); 2189 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2190 options.ciphers); 2191 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2192 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2193 2194 if (options.compression == COMP_NONE) { 2195 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2196 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2197 } 2198 2199 if (options.rekey_limit || options.rekey_interval) 2200 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 2201 options.rekey_interval); 2202 2203 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2204 list_hostkey_types()); 2205 2206 /* start key exchange */ 2207 if ((r = kex_setup(ssh, myproposal)) != 0) 2208 fatal("kex_setup: %s", ssh_err(r)); 2209 kex = ssh->kex; 2210 #ifdef WITH_OPENSSL 2211 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 2212 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 2213 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 2214 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 2215 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 2216 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2217 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2218 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 2219 #endif 2220 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 2221 kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_server; 2222 kex->load_host_public_key=&get_hostkey_public_by_type; 2223 kex->load_host_private_key=&get_hostkey_private_by_type; 2224 kex->host_key_index=&get_hostkey_index; 2225 kex->sign = sshd_hostkey_sign; 2226 2227 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 2228 2229 session_id2 = kex->session_id; 2230 session_id2_len = kex->session_id_len; 2231 2232 #ifdef DEBUG_KEXDH 2233 /* send 1st encrypted/maced/compressed message */ 2234 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 2235 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 2236 (r = sshpkt_send(ssh)) != 0 || 2237 (r = ssh_packet_write_wait(ssh)) != 0) 2238 fatal("%s: send test: %s", __func__, ssh_err(r)); 2239 #endif 2240 debug("KEX done"); 2241 } 2242 2243 /* server specific fatal cleanup */ 2244 void 2245 cleanup_exit(int i) 2246 { 2247 if (the_active_state != NULL && the_authctxt != NULL) { 2248 do_cleanup(the_active_state, the_authctxt); 2249 if (use_privsep && privsep_is_preauth && 2250 pmonitor != NULL && pmonitor->m_pid > 1) { 2251 debug("Killing privsep child %d", pmonitor->m_pid); 2252 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2253 errno != ESRCH) 2254 error("%s: kill(%d): %s", __func__, 2255 pmonitor->m_pid, strerror(errno)); 2256 } 2257 } 2258 _exit(i); 2259 } 2260