1 /* $OpenBSD: sshd.c,v 1.549 2020/01/31 23:13:04 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 alarm(0); /* alarm timer persists across exec */ 298 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 299 execv(saved_argv[0], saved_argv); 300 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 301 strerror(errno)); 302 exit(1); 303 } 304 305 /* 306 * Generic signal handler for terminating signals in the master daemon. 307 */ 308 /*ARGSUSED*/ 309 static void 310 sigterm_handler(int sig) 311 { 312 received_sigterm = sig; 313 } 314 315 /* 316 * SIGCHLD handler. This is called whenever a child dies. This will then 317 * reap any zombies left by exited children. 318 */ 319 /*ARGSUSED*/ 320 static void 321 main_sigchld_handler(int sig) 322 { 323 int save_errno = errno; 324 pid_t pid; 325 int status; 326 327 debug("main_sigchld_handler: %s", strsignal(sig)); 328 329 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 330 (pid == -1 && errno == EINTR)) 331 ; 332 errno = save_errno; 333 } 334 335 /* 336 * Signal handler for the alarm after the login grace period has expired. 337 */ 338 /*ARGSUSED*/ 339 static void 340 grace_alarm_handler(int sig) 341 { 342 if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) 343 kill(pmonitor->m_pid, SIGALRM); 344 345 /* 346 * Try to kill any processes that we have spawned, E.g. authorized 347 * keys command helpers. 348 */ 349 if (getpgid(0) == getpid()) { 350 ssh_signal(SIGTERM, SIG_IGN); 351 kill(0, SIGTERM); 352 } 353 354 /* XXX pre-format ipaddr/port so we don't need to access active_state */ 355 /* Log error and exit. */ 356 sigdie("Timeout before authentication for %s port %d", 357 ssh_remote_ipaddr(the_active_state), 358 ssh_remote_port(the_active_state)); 359 } 360 361 /* Destroy the host and server keys. They will no longer be needed. */ 362 void 363 destroy_sensitive_data(void) 364 { 365 u_int i; 366 367 for (i = 0; i < options.num_host_key_files; i++) { 368 if (sensitive_data.host_keys[i]) { 369 sshkey_free(sensitive_data.host_keys[i]); 370 sensitive_data.host_keys[i] = NULL; 371 } 372 if (sensitive_data.host_certificates[i]) { 373 sshkey_free(sensitive_data.host_certificates[i]); 374 sensitive_data.host_certificates[i] = NULL; 375 } 376 } 377 } 378 379 /* Demote private to public keys for network child */ 380 void 381 demote_sensitive_data(void) 382 { 383 struct sshkey *tmp; 384 u_int i; 385 int r; 386 387 for (i = 0; i < options.num_host_key_files; i++) { 388 if (sensitive_data.host_keys[i]) { 389 if ((r = sshkey_from_private( 390 sensitive_data.host_keys[i], &tmp)) != 0) 391 fatal("could not demote host %s key: %s", 392 sshkey_type(sensitive_data.host_keys[i]), 393 ssh_err(r)); 394 sshkey_free(sensitive_data.host_keys[i]); 395 sensitive_data.host_keys[i] = tmp; 396 } 397 /* Certs do not need demotion */ 398 } 399 } 400 401 static void 402 privsep_preauth_child(void) 403 { 404 gid_t gidset[1]; 405 struct passwd *pw; 406 407 /* Enable challenge-response authentication for privilege separation */ 408 privsep_challenge_enable(); 409 410 #ifdef GSSAPI 411 /* Cache supported mechanism OIDs for later use */ 412 ssh_gssapi_prepare_supported_oids(); 413 #endif 414 415 /* Demote the private keys to public keys. */ 416 demote_sensitive_data(); 417 418 /* Demote the child */ 419 if (getuid() == 0 || geteuid() == 0) { 420 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) 421 fatal("Privilege separation user %s does not exist", 422 SSH_PRIVSEP_USER); 423 pw = pwcopy(pw); /* Ensure mutable */ 424 endpwent(); 425 freezero(pw->pw_passwd, strlen(pw->pw_passwd)); 426 427 /* Change our root directory */ 428 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 429 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 430 strerror(errno)); 431 if (chdir("/") == -1) 432 fatal("chdir(\"/\"): %s", strerror(errno)); 433 434 /* 435 * Drop our privileges 436 * NB. Can't use setusercontext() after chroot. 437 */ 438 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, 439 (u_int)pw->pw_gid); 440 gidset[0] = pw->pw_gid; 441 if (setgroups(1, gidset) == -1) 442 fatal("setgroups: %.100s", strerror(errno)); 443 permanently_set_uid(pw); 444 } 445 } 446 447 static int 448 privsep_preauth(struct ssh *ssh) 449 { 450 int status, r; 451 pid_t pid; 452 struct ssh_sandbox *box = NULL; 453 454 /* Set up unprivileged child process to deal with network data */ 455 pmonitor = monitor_init(); 456 /* Store a pointer to the kex for later rekeying */ 457 pmonitor->m_pkex = &ssh->kex; 458 459 if (use_privsep == PRIVSEP_ON) 460 box = ssh_sandbox_init(); 461 pid = fork(); 462 if (pid == -1) { 463 fatal("fork of unprivileged child failed"); 464 } else if (pid != 0) { 465 debug2("Network child is on pid %ld", (long)pid); 466 467 pmonitor->m_pid = pid; 468 if (have_agent) { 469 r = ssh_get_authentication_socket(&auth_sock); 470 if (r != 0) { 471 error("Could not get agent socket: %s", 472 ssh_err(r)); 473 have_agent = 0; 474 } 475 } 476 if (box != NULL) 477 ssh_sandbox_parent_preauth(box, pid); 478 monitor_child_preauth(ssh, pmonitor); 479 480 /* Wait for the child's exit status */ 481 while (waitpid(pid, &status, 0) == -1) { 482 if (errno == EINTR) 483 continue; 484 pmonitor->m_pid = -1; 485 fatal("%s: waitpid: %s", __func__, strerror(errno)); 486 } 487 privsep_is_preauth = 0; 488 pmonitor->m_pid = -1; 489 if (WIFEXITED(status)) { 490 if (WEXITSTATUS(status) != 0) 491 fatal("%s: preauth child exited with status %d", 492 __func__, WEXITSTATUS(status)); 493 } else if (WIFSIGNALED(status)) 494 fatal("%s: preauth child terminated by signal %d", 495 __func__, WTERMSIG(status)); 496 if (box != NULL) 497 ssh_sandbox_parent_finish(box); 498 return 1; 499 } else { 500 /* child */ 501 close(pmonitor->m_sendfd); 502 close(pmonitor->m_log_recvfd); 503 504 /* Arrange for logging to be sent to the monitor */ 505 set_log_handler(mm_log_handler, pmonitor); 506 507 privsep_preauth_child(); 508 setproctitle("%s", "[net]"); 509 if (box != NULL) 510 ssh_sandbox_child(box); 511 512 return 0; 513 } 514 } 515 516 static void 517 privsep_postauth(struct ssh *ssh, Authctxt *authctxt) 518 { 519 if (authctxt->pw->pw_uid == 0) { 520 /* File descriptor passing is broken or root login */ 521 use_privsep = 0; 522 goto skip; 523 } 524 525 /* New socket pair */ 526 monitor_reinit(pmonitor); 527 528 pmonitor->m_pid = fork(); 529 if (pmonitor->m_pid == -1) 530 fatal("fork of unprivileged child failed"); 531 else if (pmonitor->m_pid != 0) { 532 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 533 sshbuf_reset(loginmsg); 534 monitor_clear_keystate(ssh, pmonitor); 535 monitor_child_postauth(ssh, pmonitor); 536 537 /* NEVERREACHED */ 538 exit(0); 539 } 540 541 /* child */ 542 543 close(pmonitor->m_sendfd); 544 pmonitor->m_sendfd = -1; 545 546 /* Demote the private keys to public keys. */ 547 demote_sensitive_data(); 548 549 /* Drop privileges */ 550 do_setusercontext(authctxt->pw); 551 552 skip: 553 /* It is safe now to apply the key state */ 554 monitor_apply_keystate(ssh, pmonitor); 555 556 /* 557 * Tell the packet layer that authentication was successful, since 558 * this information is not part of the key state. 559 */ 560 ssh_packet_set_authenticated(ssh); 561 } 562 563 static void 564 append_hostkey_type(struct sshbuf *b, const char *s) 565 { 566 int r; 567 568 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 569 debug3("%s: %s key not permitted by HostkeyAlgorithms", 570 __func__, s); 571 return; 572 } 573 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 574 fatal("%s: sshbuf_putf: %s", __func__, ssh_err(r)); 575 } 576 577 static char * 578 list_hostkey_types(void) 579 { 580 struct sshbuf *b; 581 struct sshkey *key; 582 char *ret; 583 u_int i; 584 585 if ((b = sshbuf_new()) == NULL) 586 fatal("%s: sshbuf_new failed", __func__); 587 for (i = 0; i < options.num_host_key_files; i++) { 588 key = sensitive_data.host_keys[i]; 589 if (key == NULL) 590 key = sensitive_data.host_pubkeys[i]; 591 if (key == NULL) 592 continue; 593 switch (key->type) { 594 case KEY_RSA: 595 /* for RSA we also support SHA2 signatures */ 596 append_hostkey_type(b, "rsa-sha2-512"); 597 append_hostkey_type(b, "rsa-sha2-256"); 598 /* FALLTHROUGH */ 599 case KEY_DSA: 600 case KEY_ECDSA: 601 case KEY_ED25519: 602 case KEY_ECDSA_SK: 603 case KEY_ED25519_SK: 604 case KEY_XMSS: 605 append_hostkey_type(b, sshkey_ssh_name(key)); 606 break; 607 } 608 /* If the private key has a cert peer, then list that too */ 609 key = sensitive_data.host_certificates[i]; 610 if (key == NULL) 611 continue; 612 switch (key->type) { 613 case KEY_RSA_CERT: 614 /* for RSA we also support SHA2 signatures */ 615 append_hostkey_type(b, 616 "rsa-sha2-512-cert-v01@openssh.com"); 617 append_hostkey_type(b, 618 "rsa-sha2-256-cert-v01@openssh.com"); 619 /* FALLTHROUGH */ 620 case KEY_DSA_CERT: 621 case KEY_ECDSA_CERT: 622 case KEY_ED25519_CERT: 623 case KEY_ECDSA_SK_CERT: 624 case KEY_ED25519_SK_CERT: 625 case KEY_XMSS_CERT: 626 append_hostkey_type(b, sshkey_ssh_name(key)); 627 break; 628 } 629 } 630 if ((ret = sshbuf_dup_string(b)) == NULL) 631 fatal("%s: sshbuf_dup_string failed", __func__); 632 sshbuf_free(b); 633 debug("%s: %s", __func__, ret); 634 return ret; 635 } 636 637 static struct sshkey * 638 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 639 { 640 u_int i; 641 struct sshkey *key; 642 643 for (i = 0; i < options.num_host_key_files; i++) { 644 switch (type) { 645 case KEY_RSA_CERT: 646 case KEY_DSA_CERT: 647 case KEY_ECDSA_CERT: 648 case KEY_ED25519_CERT: 649 case KEY_ECDSA_SK_CERT: 650 case KEY_ED25519_SK_CERT: 651 case KEY_XMSS_CERT: 652 key = sensitive_data.host_certificates[i]; 653 break; 654 default: 655 key = sensitive_data.host_keys[i]; 656 if (key == NULL && !need_private) 657 key = sensitive_data.host_pubkeys[i]; 658 break; 659 } 660 if (key == NULL || key->type != type) 661 continue; 662 switch (type) { 663 case KEY_ECDSA: 664 case KEY_ECDSA_SK: 665 case KEY_ECDSA_CERT: 666 case KEY_ECDSA_SK_CERT: 667 if (key->ecdsa_nid != nid) 668 continue; 669 /* FALLTHROUGH */ 670 default: 671 return need_private ? 672 sensitive_data.host_keys[i] : key; 673 } 674 } 675 return NULL; 676 } 677 678 struct sshkey * 679 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 680 { 681 return get_hostkey_by_type(type, nid, 0, ssh); 682 } 683 684 struct sshkey * 685 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 686 { 687 return get_hostkey_by_type(type, nid, 1, ssh); 688 } 689 690 struct sshkey * 691 get_hostkey_by_index(int ind) 692 { 693 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 694 return (NULL); 695 return (sensitive_data.host_keys[ind]); 696 } 697 698 struct sshkey * 699 get_hostkey_public_by_index(int ind, struct ssh *ssh) 700 { 701 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 702 return (NULL); 703 return (sensitive_data.host_pubkeys[ind]); 704 } 705 706 int 707 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 708 { 709 u_int i; 710 711 for (i = 0; i < options.num_host_key_files; i++) { 712 if (sshkey_is_cert(key)) { 713 if (key == sensitive_data.host_certificates[i] || 714 (compare && sensitive_data.host_certificates[i] && 715 sshkey_equal(key, 716 sensitive_data.host_certificates[i]))) 717 return (i); 718 } else { 719 if (key == sensitive_data.host_keys[i] || 720 (compare && sensitive_data.host_keys[i] && 721 sshkey_equal(key, sensitive_data.host_keys[i]))) 722 return (i); 723 if (key == sensitive_data.host_pubkeys[i] || 724 (compare && sensitive_data.host_pubkeys[i] && 725 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 726 return (i); 727 } 728 } 729 return (-1); 730 } 731 732 /* Inform the client of all hostkeys */ 733 static void 734 notify_hostkeys(struct ssh *ssh) 735 { 736 struct sshbuf *buf; 737 struct sshkey *key; 738 u_int i, nkeys; 739 int r; 740 char *fp; 741 742 /* Some clients cannot cope with the hostkeys message, skip those. */ 743 if (ssh->compat & SSH_BUG_HOSTKEYS) 744 return; 745 746 if ((buf = sshbuf_new()) == NULL) 747 fatal("%s: sshbuf_new", __func__); 748 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 749 key = get_hostkey_public_by_index(i, ssh); 750 if (key == NULL || key->type == KEY_UNSPEC || 751 sshkey_is_cert(key)) 752 continue; 753 fp = sshkey_fingerprint(key, options.fingerprint_hash, 754 SSH_FP_DEFAULT); 755 debug3("%s: key %d: %s %s", __func__, i, 756 sshkey_ssh_name(key), fp); 757 free(fp); 758 if (nkeys == 0) { 759 /* 760 * Start building the request when we find the 761 * first usable key. 762 */ 763 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 764 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || 765 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ 766 sshpkt_fatal(ssh, r, "%s: start request", __func__); 767 } 768 /* Append the key to the request */ 769 sshbuf_reset(buf); 770 if ((r = sshkey_putb(key, buf)) != 0) 771 fatal("%s: couldn't put hostkey %d: %s", 772 __func__, i, ssh_err(r)); 773 if ((r = sshpkt_put_stringb(ssh, buf)) != 0) 774 sshpkt_fatal(ssh, r, "%s: append key", __func__); 775 nkeys++; 776 } 777 debug3("%s: sent %u hostkeys", __func__, nkeys); 778 if (nkeys == 0) 779 fatal("%s: no hostkeys", __func__); 780 if ((r = sshpkt_send(ssh)) != 0) 781 sshpkt_fatal(ssh, r, "%s: send", __func__); 782 sshbuf_free(buf); 783 } 784 785 /* 786 * returns 1 if connection should be dropped, 0 otherwise. 787 * dropping starts at connection #max_startups_begin with a probability 788 * of (max_startups_rate/100). the probability increases linearly until 789 * all connections are dropped for startups > max_startups 790 */ 791 static int 792 drop_connection(int startups) 793 { 794 int p, r; 795 796 if (startups < options.max_startups_begin) 797 return 0; 798 if (startups >= options.max_startups) 799 return 1; 800 if (options.max_startups_rate == 100) 801 return 1; 802 803 p = 100 - options.max_startups_rate; 804 p *= startups - options.max_startups_begin; 805 p /= options.max_startups - options.max_startups_begin; 806 p += options.max_startups_rate; 807 r = arc4random_uniform(100); 808 809 debug("drop_connection: p %d, r %d", p, r); 810 return (r < p) ? 1 : 0; 811 } 812 813 static void 814 usage(void) 815 { 816 fprintf(stderr, "%s, %s\n", 817 SSH_VERSION, 818 #ifdef WITH_OPENSSL 819 OpenSSL_version(OPENSSL_VERSION) 820 #else 821 "without OpenSSL" 822 #endif 823 ); 824 fprintf(stderr, 825 "usage: sshd [-46DdeiqTt] [-C connection_spec] [-c host_cert_file]\n" 826 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 827 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 828 ); 829 exit(1); 830 } 831 832 static void 833 send_rexec_state(int fd, struct sshbuf *conf) 834 { 835 struct sshbuf *m = NULL, *inc = NULL; 836 struct include_item *item = NULL; 837 int r; 838 839 debug3("%s: entering fd = %d config len %zu", __func__, fd, 840 sshbuf_len(conf)); 841 842 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 843 fatal("%s: sshbuf_new failed", __func__); 844 845 /* pack includes into a string */ 846 TAILQ_FOREACH(item, &includes, entry) { 847 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 848 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 849 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 850 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 851 } 852 853 /* 854 * Protocol from reexec master to child: 855 * string configuration 856 * string included_files[] { 857 * string selector 858 * string filename 859 * string contents 860 * } 861 */ 862 if ((r = sshbuf_put_stringb(m, conf)) != 0 || 863 (r = sshbuf_put_stringb(m, inc)) != 0) 864 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 865 if (ssh_msg_send(fd, 0, m) == -1) 866 fatal("%s: ssh_msg_send failed", __func__); 867 868 sshbuf_free(m); 869 sshbuf_free(inc); 870 871 debug3("%s: done", __func__); 872 } 873 874 static void 875 recv_rexec_state(int fd, struct sshbuf *conf) 876 { 877 struct sshbuf *m, *inc; 878 u_char *cp, ver; 879 size_t len; 880 int r; 881 struct include_item *item; 882 883 debug3("%s: entering fd = %d", __func__, fd); 884 885 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 886 fatal("%s: sshbuf_new failed", __func__); 887 if (ssh_msg_recv(fd, m) == -1) 888 fatal("%s: ssh_msg_recv failed", __func__); 889 if ((r = sshbuf_get_u8(m, &ver)) != 0) 890 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 891 if (ver != 0) 892 fatal("%s: rexec version mismatch", __func__); 893 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || 894 (r = sshbuf_get_stringb(m, inc)) != 0) 895 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 896 897 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 898 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 899 900 while (sshbuf_len(inc) != 0) { 901 item = xcalloc(1, sizeof(*item)); 902 if ((item->contents = sshbuf_new()) == NULL) 903 fatal("%s: sshbuf_new failed", __func__); 904 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 || 905 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 || 906 (r = sshbuf_get_stringb(inc, item->contents)) != 0) 907 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 908 TAILQ_INSERT_TAIL(&includes, item, entry); 909 } 910 911 free(cp); 912 sshbuf_free(m); 913 914 debug3("%s: done", __func__); 915 } 916 917 /* Accept a connection from inetd */ 918 static void 919 server_accept_inetd(int *sock_in, int *sock_out) 920 { 921 int fd; 922 923 if (rexeced_flag) { 924 close(REEXEC_CONFIG_PASS_FD); 925 *sock_in = *sock_out = dup(STDIN_FILENO); 926 } else { 927 *sock_in = dup(STDIN_FILENO); 928 *sock_out = dup(STDOUT_FILENO); 929 } 930 /* 931 * We intentionally do not close the descriptors 0, 1, and 2 932 * as our code for setting the descriptors won't work if 933 * ttyfd happens to be one of those. 934 */ 935 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 936 dup2(fd, STDIN_FILENO); 937 dup2(fd, STDOUT_FILENO); 938 if (!log_stderr) 939 dup2(fd, STDERR_FILENO); 940 if (fd > (log_stderr ? STDERR_FILENO : STDOUT_FILENO)) 941 close(fd); 942 } 943 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 944 } 945 946 /* 947 * Listen for TCP connections 948 */ 949 static void 950 listen_on_addrs(struct listenaddr *la) 951 { 952 int ret, listen_sock; 953 struct addrinfo *ai; 954 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 955 956 for (ai = la->addrs; ai; ai = ai->ai_next) { 957 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 958 continue; 959 if (num_listen_socks >= MAX_LISTEN_SOCKS) 960 fatal("Too many listen sockets. " 961 "Enlarge MAX_LISTEN_SOCKS"); 962 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 963 ntop, sizeof(ntop), strport, sizeof(strport), 964 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 965 error("getnameinfo failed: %.100s", 966 ssh_gai_strerror(ret)); 967 continue; 968 } 969 /* Create socket for listening. */ 970 listen_sock = socket(ai->ai_family, ai->ai_socktype, 971 ai->ai_protocol); 972 if (listen_sock == -1) { 973 /* kernel may not support ipv6 */ 974 verbose("socket: %.100s", strerror(errno)); 975 continue; 976 } 977 if (set_nonblock(listen_sock) == -1) { 978 close(listen_sock); 979 continue; 980 } 981 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 982 verbose("socket: CLOEXEC: %s", strerror(errno)); 983 close(listen_sock); 984 continue; 985 } 986 /* Socket options */ 987 set_reuseaddr(listen_sock); 988 if (la->rdomain != NULL && 989 set_rdomain(listen_sock, la->rdomain) == -1) { 990 close(listen_sock); 991 continue; 992 } 993 994 debug("Bind to port %s on %s.", strport, ntop); 995 996 /* Bind the socket to the desired port. */ 997 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 998 error("Bind to port %s on %s failed: %.200s.", 999 strport, ntop, strerror(errno)); 1000 close(listen_sock); 1001 continue; 1002 } 1003 listen_socks[num_listen_socks] = listen_sock; 1004 num_listen_socks++; 1005 1006 /* Start listening on the port. */ 1007 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 1008 fatal("listen on [%s]:%s: %.100s", 1009 ntop, strport, strerror(errno)); 1010 logit("Server listening on %s port %s%s%s.", 1011 ntop, strport, 1012 la->rdomain == NULL ? "" : " rdomain ", 1013 la->rdomain == NULL ? "" : la->rdomain); 1014 } 1015 } 1016 1017 static void 1018 server_listen(void) 1019 { 1020 u_int i; 1021 1022 for (i = 0; i < options.num_listen_addrs; i++) { 1023 listen_on_addrs(&options.listen_addrs[i]); 1024 freeaddrinfo(options.listen_addrs[i].addrs); 1025 free(options.listen_addrs[i].rdomain); 1026 memset(&options.listen_addrs[i], 0, 1027 sizeof(options.listen_addrs[i])); 1028 } 1029 free(options.listen_addrs); 1030 options.listen_addrs = NULL; 1031 options.num_listen_addrs = 0; 1032 1033 if (!num_listen_socks) 1034 fatal("Cannot bind any address."); 1035 } 1036 1037 /* 1038 * The main TCP accept loop. Note that, for the non-debug case, returns 1039 * from this function are in a forked subprocess. 1040 */ 1041 static void 1042 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1043 { 1044 fd_set *fdset; 1045 int i, j, ret, maxfd; 1046 int ostartups = -1, startups = 0, listening = 0, lameduck = 0; 1047 int startup_p[2] = { -1 , -1 }; 1048 char c = 0; 1049 struct sockaddr_storage from; 1050 socklen_t fromlen; 1051 pid_t pid; 1052 1053 /* setup fd set for accept */ 1054 fdset = NULL; 1055 maxfd = 0; 1056 for (i = 0; i < num_listen_socks; i++) 1057 if (listen_socks[i] > maxfd) 1058 maxfd = listen_socks[i]; 1059 /* pipes connected to unauthenticated childs */ 1060 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1061 startup_flags = xcalloc(options.max_startups, sizeof(int)); 1062 for (i = 0; i < options.max_startups; i++) 1063 startup_pipes[i] = -1; 1064 1065 /* 1066 * Stay listening for connections until the system crashes or 1067 * the daemon is killed with a signal. 1068 */ 1069 for (;;) { 1070 if (ostartups != startups) { 1071 setproctitle("%s [listener] %d of %d-%d startups", 1072 listener_proctitle, startups, 1073 options.max_startups_begin, options.max_startups); 1074 ostartups = startups; 1075 } 1076 if (received_sighup) { 1077 if (!lameduck) { 1078 debug("Received SIGHUP; waiting for children"); 1079 close_listen_socks(); 1080 lameduck = 1; 1081 } 1082 if (listening <= 0) 1083 sighup_restart(); 1084 } 1085 free(fdset); 1086 fdset = xcalloc(howmany(maxfd + 1, NFDBITS), 1087 sizeof(fd_mask)); 1088 1089 for (i = 0; i < num_listen_socks; i++) 1090 FD_SET(listen_socks[i], fdset); 1091 for (i = 0; i < options.max_startups; i++) 1092 if (startup_pipes[i] != -1) 1093 FD_SET(startup_pipes[i], fdset); 1094 1095 /* Wait in select until there is a connection. */ 1096 ret = select(maxfd+1, fdset, NULL, NULL, NULL); 1097 if (ret == -1 && errno != EINTR) 1098 error("select: %.100s", strerror(errno)); 1099 if (received_sigterm) { 1100 logit("Received signal %d; terminating.", 1101 (int) received_sigterm); 1102 close_listen_socks(); 1103 if (options.pid_file != NULL) 1104 unlink(options.pid_file); 1105 exit(received_sigterm == SIGTERM ? 0 : 255); 1106 } 1107 if (ret == -1) 1108 continue; 1109 1110 for (i = 0; i < options.max_startups; i++) { 1111 if (startup_pipes[i] == -1 || 1112 !FD_ISSET(startup_pipes[i], fdset)) 1113 continue; 1114 switch (read(startup_pipes[i], &c, sizeof(c))) { 1115 case -1: 1116 if (errno == EINTR || errno == EAGAIN) 1117 continue; 1118 if (errno != EPIPE) { 1119 error("%s: startup pipe %d (fd=%d): " 1120 "read %s", __func__, i, 1121 startup_pipes[i], strerror(errno)); 1122 } 1123 /* FALLTHROUGH */ 1124 case 0: 1125 /* child exited or completed auth */ 1126 close(startup_pipes[i]); 1127 startup_pipes[i] = -1; 1128 startups--; 1129 if (startup_flags[i]) 1130 listening--; 1131 break; 1132 case 1: 1133 /* child has finished preliminaries */ 1134 if (startup_flags[i]) { 1135 listening--; 1136 startup_flags[i] = 0; 1137 } 1138 break; 1139 } 1140 } 1141 for (i = 0; i < num_listen_socks; i++) { 1142 if (!FD_ISSET(listen_socks[i], fdset)) 1143 continue; 1144 fromlen = sizeof(from); 1145 *newsock = accept(listen_socks[i], 1146 (struct sockaddr *)&from, &fromlen); 1147 if (*newsock == -1) { 1148 if (errno != EINTR && errno != EWOULDBLOCK && 1149 errno != ECONNABORTED) 1150 error("accept: %.100s", 1151 strerror(errno)); 1152 if (errno == EMFILE || errno == ENFILE) 1153 usleep(100 * 1000); 1154 continue; 1155 } 1156 if (unset_nonblock(*newsock) == -1) { 1157 close(*newsock); 1158 continue; 1159 } 1160 if (drop_connection(startups) == 1) { 1161 char *laddr = get_local_ipaddr(*newsock); 1162 char *raddr = get_peer_ipaddr(*newsock); 1163 char msg[] = "Exceeded MaxStartups\r\n"; 1164 1165 verbose("drop connection #%d from [%s]:%d " 1166 "on [%s]:%d past MaxStartups", startups, 1167 raddr, get_peer_port(*newsock), 1168 laddr, get_local_port(*newsock)); 1169 free(laddr); 1170 free(raddr); 1171 /* best-effort notification to client */ 1172 (void)write(*newsock, msg, strlen(msg)); 1173 close(*newsock); 1174 continue; 1175 } 1176 if (pipe(startup_p) == -1) { 1177 close(*newsock); 1178 continue; 1179 } 1180 1181 if (rexec_flag && socketpair(AF_UNIX, 1182 SOCK_STREAM, 0, config_s) == -1) { 1183 error("reexec socketpair: %s", 1184 strerror(errno)); 1185 close(*newsock); 1186 close(startup_p[0]); 1187 close(startup_p[1]); 1188 continue; 1189 } 1190 1191 for (j = 0; j < options.max_startups; j++) 1192 if (startup_pipes[j] == -1) { 1193 startup_pipes[j] = startup_p[0]; 1194 if (maxfd < startup_p[0]) 1195 maxfd = startup_p[0]; 1196 startups++; 1197 startup_flags[j] = 1; 1198 break; 1199 } 1200 1201 /* 1202 * Got connection. Fork a child to handle it, unless 1203 * we are in debugging mode. 1204 */ 1205 if (debug_flag) { 1206 /* 1207 * In debugging mode. Close the listening 1208 * socket, and start processing the 1209 * connection without forking. 1210 */ 1211 debug("Server will not fork when running in debugging mode."); 1212 close_listen_socks(); 1213 *sock_in = *newsock; 1214 *sock_out = *newsock; 1215 close(startup_p[0]); 1216 close(startup_p[1]); 1217 startup_pipe = -1; 1218 pid = getpid(); 1219 if (rexec_flag) { 1220 send_rexec_state(config_s[0], cfg); 1221 close(config_s[0]); 1222 } 1223 return; 1224 } 1225 1226 /* 1227 * Normal production daemon. Fork, and have 1228 * the child process the connection. The 1229 * parent continues listening. 1230 */ 1231 listening++; 1232 if ((pid = fork()) == 0) { 1233 /* 1234 * Child. Close the listening and 1235 * max_startup sockets. Start using 1236 * the accepted socket. Reinitialize 1237 * logging (since our pid has changed). 1238 * We return from this function to handle 1239 * the connection. 1240 */ 1241 startup_pipe = startup_p[1]; 1242 close_startup_pipes(); 1243 close_listen_socks(); 1244 *sock_in = *newsock; 1245 *sock_out = *newsock; 1246 log_init(__progname, 1247 options.log_level, 1248 options.log_facility, 1249 log_stderr); 1250 if (rexec_flag) 1251 close(config_s[0]); 1252 else { 1253 /* 1254 * Signal parent that the preliminaries 1255 * for this child are complete. For the 1256 * re-exec case, this happens after the 1257 * child has received the rexec state 1258 * from the server. 1259 */ 1260 (void)atomicio(vwrite, startup_pipe, 1261 "\0", 1); 1262 } 1263 return; 1264 } 1265 1266 /* Parent. Stay in the loop. */ 1267 if (pid == -1) 1268 error("fork: %.100s", strerror(errno)); 1269 else 1270 debug("Forked child %ld.", (long)pid); 1271 1272 close(startup_p[1]); 1273 1274 if (rexec_flag) { 1275 send_rexec_state(config_s[0], cfg); 1276 close(config_s[0]); 1277 close(config_s[1]); 1278 } 1279 close(*newsock); 1280 } 1281 } 1282 } 1283 1284 /* 1285 * If IP options are supported, make sure there are none (log and 1286 * return an error if any are found). Basically we are worried about 1287 * source routing; it can be used to pretend you are somebody 1288 * (ip-address) you are not. That itself may be "almost acceptable" 1289 * under certain circumstances, but rhosts authentication is useless 1290 * if source routing is accepted. Notice also that if we just dropped 1291 * source routing here, the other side could use IP spoofing to do 1292 * rest of the interaction and could still bypass security. So we 1293 * exit here if we detect any IP options. 1294 */ 1295 static void 1296 check_ip_options(struct ssh *ssh) 1297 { 1298 int sock_in = ssh_packet_get_connection_in(ssh); 1299 struct sockaddr_storage from; 1300 u_char opts[200]; 1301 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1302 char text[sizeof(opts) * 3 + 1]; 1303 1304 memset(&from, 0, sizeof(from)); 1305 if (getpeername(sock_in, (struct sockaddr *)&from, 1306 &fromlen) == -1) 1307 return; 1308 if (from.ss_family != AF_INET) 1309 return; 1310 /* XXX IPv6 options? */ 1311 1312 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1313 &option_size) >= 0 && option_size != 0) { 1314 text[0] = '\0'; 1315 for (i = 0; i < option_size; i++) 1316 snprintf(text + i*3, sizeof(text) - i*3, 1317 " %2.2x", opts[i]); 1318 fatal("Connection from %.100s port %d with IP opts: %.800s", 1319 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1320 } 1321 return; 1322 } 1323 1324 /* Set the routing domain for this process */ 1325 static void 1326 set_process_rdomain(struct ssh *ssh, const char *name) 1327 { 1328 int rtable, ortable = getrtable(); 1329 const char *errstr; 1330 1331 if (name == NULL) 1332 return; /* default */ 1333 1334 if (strcmp(name, "%D") == 0) { 1335 /* "expands" to routing domain of connection */ 1336 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1337 return; 1338 } 1339 1340 rtable = (int)strtonum(name, 0, 255, &errstr); 1341 if (errstr != NULL) /* Shouldn't happen */ 1342 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1343 if (rtable != ortable && setrtable(rtable) != 0) 1344 fatal("Unable to set routing domain %d: %s", 1345 rtable, strerror(errno)); 1346 debug("%s: set routing domain %d (was %d)", __func__, rtable, ortable); 1347 } 1348 1349 static void 1350 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1351 struct sshkey *key) 1352 { 1353 static struct ssh_digest_ctx *ctx; 1354 u_char *hash; 1355 size_t len; 1356 struct sshbuf *buf; 1357 int r; 1358 1359 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1360 fatal("%s: ssh_digest_start", __func__); 1361 if (key == NULL) { /* finalize */ 1362 /* add server config in case we are using agent for host keys */ 1363 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1364 sshbuf_len(server_cfg)) != 0) 1365 fatal("%s: ssh_digest_update", __func__); 1366 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1367 hash = xmalloc(len); 1368 if (ssh_digest_final(ctx, hash, len) != 0) 1369 fatal("%s: ssh_digest_final", __func__); 1370 options.timing_secret = PEEK_U64(hash); 1371 freezero(hash, len); 1372 ssh_digest_free(ctx); 1373 ctx = NULL; 1374 return; 1375 } 1376 if ((buf = sshbuf_new()) == NULL) 1377 fatal("%s could not allocate buffer", __func__); 1378 if ((r = sshkey_private_serialize(key, buf)) != 0) 1379 fatal("sshkey_private_serialize: %s", ssh_err(r)); 1380 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1381 fatal("%s: ssh_digest_update", __func__); 1382 sshbuf_reset(buf); 1383 sshbuf_free(buf); 1384 } 1385 1386 static char * 1387 prepare_proctitle(int ac, char **av) 1388 { 1389 char *ret = NULL; 1390 int i; 1391 1392 for (i = 0; i < ac; i++) 1393 xextendf(&ret, " ", "%s", av[i]); 1394 return ret; 1395 } 1396 1397 /* 1398 * Main program for the daemon. 1399 */ 1400 int 1401 main(int ac, char **av) 1402 { 1403 struct ssh *ssh = NULL; 1404 extern char *optarg; 1405 extern int optind; 1406 int r, opt, on = 1, already_daemon, remote_port; 1407 int sock_in = -1, sock_out = -1, newsock = -1; 1408 const char *remote_ip, *rdomain; 1409 char *fp, *line, *laddr, *logfile = NULL; 1410 int config_s[2] = { -1 , -1 }; 1411 u_int i, j; 1412 u_int64_t ibytes, obytes; 1413 mode_t new_umask; 1414 struct sshkey *key; 1415 struct sshkey *pubkey; 1416 int keytype; 1417 Authctxt *authctxt; 1418 struct connection_info *connection_info = NULL; 1419 1420 /* Save argv. */ 1421 saved_argv = av; 1422 rexec_argc = ac; 1423 1424 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1425 sanitise_stdfd(); 1426 1427 /* Initialize configuration options to their default values. */ 1428 initialize_server_options(&options); 1429 1430 /* Parse command-line arguments. */ 1431 while ((opt = getopt(ac, av, 1432 "C:E:b:c:f:g:h:k:o:p:u:46DQRTdeiqrt")) != -1) { 1433 switch (opt) { 1434 case '4': 1435 options.address_family = AF_INET; 1436 break; 1437 case '6': 1438 options.address_family = AF_INET6; 1439 break; 1440 case 'f': 1441 config_file_name = optarg; 1442 break; 1443 case 'c': 1444 servconf_add_hostcert("[command-line]", 0, 1445 &options, optarg); 1446 break; 1447 case 'd': 1448 if (debug_flag == 0) { 1449 debug_flag = 1; 1450 options.log_level = SYSLOG_LEVEL_DEBUG1; 1451 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1452 options.log_level++; 1453 break; 1454 case 'D': 1455 no_daemon_flag = 1; 1456 break; 1457 case 'E': 1458 logfile = optarg; 1459 /* FALLTHROUGH */ 1460 case 'e': 1461 log_stderr = 1; 1462 break; 1463 case 'i': 1464 inetd_flag = 1; 1465 break; 1466 case 'r': 1467 rexec_flag = 0; 1468 break; 1469 case 'R': 1470 rexeced_flag = 1; 1471 inetd_flag = 1; 1472 break; 1473 case 'Q': 1474 /* ignored */ 1475 break; 1476 case 'q': 1477 options.log_level = SYSLOG_LEVEL_QUIET; 1478 break; 1479 case 'b': 1480 /* protocol 1, ignored */ 1481 break; 1482 case 'p': 1483 options.ports_from_cmdline = 1; 1484 if (options.num_ports >= MAX_PORTS) { 1485 fprintf(stderr, "too many ports.\n"); 1486 exit(1); 1487 } 1488 options.ports[options.num_ports++] = a2port(optarg); 1489 if (options.ports[options.num_ports-1] <= 0) { 1490 fprintf(stderr, "Bad port number.\n"); 1491 exit(1); 1492 } 1493 break; 1494 case 'g': 1495 if ((options.login_grace_time = convtime(optarg)) == -1) { 1496 fprintf(stderr, "Invalid login grace time.\n"); 1497 exit(1); 1498 } 1499 break; 1500 case 'k': 1501 /* protocol 1, ignored */ 1502 break; 1503 case 'h': 1504 servconf_add_hostkey("[command-line]", 0, 1505 &options, optarg, 1); 1506 break; 1507 case 't': 1508 test_flag = 1; 1509 break; 1510 case 'T': 1511 test_flag = 2; 1512 break; 1513 case 'C': 1514 connection_info = get_connection_info(ssh, 0, 0); 1515 if (parse_server_match_testspec(connection_info, 1516 optarg) == -1) 1517 exit(1); 1518 break; 1519 case 'u': 1520 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1521 if (utmp_len > HOST_NAME_MAX+1) { 1522 fprintf(stderr, "Invalid utmp length.\n"); 1523 exit(1); 1524 } 1525 break; 1526 case 'o': 1527 line = xstrdup(optarg); 1528 if (process_server_config_line(&options, line, 1529 "command-line", 0, NULL, NULL, &includes) != 0) 1530 exit(1); 1531 free(line); 1532 break; 1533 case '?': 1534 default: 1535 usage(); 1536 break; 1537 } 1538 } 1539 if (rexeced_flag || inetd_flag) 1540 rexec_flag = 0; 1541 if (!test_flag && rexec_flag && !path_absolute(av[0])) 1542 fatal("sshd re-exec requires execution with an absolute path"); 1543 if (rexeced_flag) 1544 closefrom(REEXEC_MIN_FREE_FD); 1545 else 1546 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1547 1548 #ifdef WITH_OPENSSL 1549 OpenSSL_add_all_algorithms(); 1550 #endif 1551 1552 /* If requested, redirect the logs to the specified logfile. */ 1553 if (logfile != NULL) 1554 log_redirect_stderr_to(logfile); 1555 /* 1556 * Force logging to stderr until we have loaded the private host 1557 * key (unless started from inetd) 1558 */ 1559 log_init(__progname, 1560 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1561 SYSLOG_LEVEL_INFO : options.log_level, 1562 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1563 SYSLOG_FACILITY_AUTH : options.log_facility, 1564 log_stderr || !inetd_flag || debug_flag); 1565 1566 sensitive_data.have_ssh2_key = 0; 1567 1568 /* 1569 * If we're not doing an extended test do not silently ignore connection 1570 * test params. 1571 */ 1572 if (test_flag < 2 && connection_info != NULL) 1573 fatal("Config test connection parameter (-C) provided without " 1574 "test mode (-T)"); 1575 1576 /* Fetch our configuration */ 1577 if ((cfg = sshbuf_new()) == NULL) 1578 fatal("%s: sshbuf_new failed", __func__); 1579 if (rexeced_flag) { 1580 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1581 if (!debug_flag) { 1582 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1583 close(REEXEC_STARTUP_PIPE_FD); 1584 /* 1585 * Signal parent that this child is at a point where 1586 * they can go away if they have a SIGHUP pending. 1587 */ 1588 (void)atomicio(vwrite, startup_pipe, "\0", 1); 1589 } 1590 } else if (strcasecmp(config_file_name, "none") != 0) 1591 load_server_config(config_file_name, cfg); 1592 1593 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1594 cfg, &includes, NULL); 1595 1596 /* Fill in default values for those options not explicitly set. */ 1597 fill_default_server_options(&options); 1598 1599 /* challenge-response is implemented via keyboard interactive */ 1600 if (options.challenge_response_authentication) 1601 options.kbd_interactive_authentication = 1; 1602 1603 /* Check that options are sensible */ 1604 if (options.authorized_keys_command_user == NULL && 1605 (options.authorized_keys_command != NULL && 1606 strcasecmp(options.authorized_keys_command, "none") != 0)) 1607 fatal("AuthorizedKeysCommand set without " 1608 "AuthorizedKeysCommandUser"); 1609 if (options.authorized_principals_command_user == NULL && 1610 (options.authorized_principals_command != NULL && 1611 strcasecmp(options.authorized_principals_command, "none") != 0)) 1612 fatal("AuthorizedPrincipalsCommand set without " 1613 "AuthorizedPrincipalsCommandUser"); 1614 1615 /* 1616 * Check whether there is any path through configured auth methods. 1617 * Unfortunately it is not possible to verify this generally before 1618 * daemonisation in the presence of Match block, but this catches 1619 * and warns for trivial misconfigurations that could break login. 1620 */ 1621 if (options.num_auth_methods != 0) { 1622 for (i = 0; i < options.num_auth_methods; i++) { 1623 if (auth2_methods_valid(options.auth_methods[i], 1624 1) == 0) 1625 break; 1626 } 1627 if (i >= options.num_auth_methods) 1628 fatal("AuthenticationMethods cannot be satisfied by " 1629 "enabled authentication methods"); 1630 } 1631 1632 /* Check that there are no remaining arguments. */ 1633 if (optind < ac) { 1634 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1635 exit(1); 1636 } 1637 1638 debug("sshd version %s, %s", SSH_VERSION, 1639 #ifdef WITH_OPENSSL 1640 OpenSSL_version(OPENSSL_VERSION) 1641 #else 1642 "without OpenSSL" 1643 #endif 1644 ); 1645 1646 /* load host keys */ 1647 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1648 sizeof(struct sshkey *)); 1649 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1650 sizeof(struct sshkey *)); 1651 1652 if (options.host_key_agent) { 1653 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1654 setenv(SSH_AUTHSOCKET_ENV_NAME, 1655 options.host_key_agent, 1); 1656 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1657 have_agent = 1; 1658 else 1659 error("Could not connect to agent \"%s\": %s", 1660 options.host_key_agent, ssh_err(r)); 1661 } 1662 1663 for (i = 0; i < options.num_host_key_files; i++) { 1664 int ll = options.host_key_file_userprovided[i] ? 1665 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1666 1667 if (options.host_key_files[i] == NULL) 1668 continue; 1669 if ((r = sshkey_load_private(options.host_key_files[i], "", 1670 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1671 do_log2(ll, "Unable to load host key \"%s\": %s", 1672 options.host_key_files[i], ssh_err(r)); 1673 if (sshkey_is_sk(key) && 1674 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1675 debug("host key %s requires user presence, ignoring", 1676 options.host_key_files[i]); 1677 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1678 } 1679 if (r == 0 && key != NULL && 1680 (r = sshkey_shield_private(key)) != 0) { 1681 do_log2(ll, "Unable to shield host key \"%s\": %s", 1682 options.host_key_files[i], ssh_err(r)); 1683 sshkey_free(key); 1684 key = NULL; 1685 } 1686 if ((r = sshkey_load_public(options.host_key_files[i], 1687 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1688 do_log2(ll, "Unable to load host key \"%s\": %s", 1689 options.host_key_files[i], ssh_err(r)); 1690 if (pubkey == NULL && key != NULL) 1691 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1692 fatal("Could not demote key: \"%s\": %s", 1693 options.host_key_files[i], ssh_err(r)); 1694 sensitive_data.host_keys[i] = key; 1695 sensitive_data.host_pubkeys[i] = pubkey; 1696 1697 if (key == NULL && pubkey != NULL && have_agent) { 1698 debug("will rely on agent for hostkey %s", 1699 options.host_key_files[i]); 1700 keytype = pubkey->type; 1701 } else if (key != NULL) { 1702 keytype = key->type; 1703 accumulate_host_timing_secret(cfg, key); 1704 } else { 1705 do_log2(ll, "Unable to load host key: %s", 1706 options.host_key_files[i]); 1707 sensitive_data.host_keys[i] = NULL; 1708 sensitive_data.host_pubkeys[i] = NULL; 1709 continue; 1710 } 1711 1712 switch (keytype) { 1713 case KEY_RSA: 1714 case KEY_DSA: 1715 case KEY_ECDSA: 1716 case KEY_ED25519: 1717 case KEY_ECDSA_SK: 1718 case KEY_ED25519_SK: 1719 case KEY_XMSS: 1720 if (have_agent || key != NULL) 1721 sensitive_data.have_ssh2_key = 1; 1722 break; 1723 } 1724 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1725 SSH_FP_DEFAULT)) == NULL) 1726 fatal("sshkey_fingerprint failed"); 1727 debug("%s host key #%d: %s %s", 1728 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1729 free(fp); 1730 } 1731 accumulate_host_timing_secret(cfg, NULL); 1732 if (!sensitive_data.have_ssh2_key) { 1733 logit("sshd: no hostkeys available -- exiting."); 1734 exit(1); 1735 } 1736 1737 /* 1738 * Load certificates. They are stored in an array at identical 1739 * indices to the public keys that they relate to. 1740 */ 1741 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1742 sizeof(struct sshkey *)); 1743 for (i = 0; i < options.num_host_key_files; i++) 1744 sensitive_data.host_certificates[i] = NULL; 1745 1746 for (i = 0; i < options.num_host_cert_files; i++) { 1747 if (options.host_cert_files[i] == NULL) 1748 continue; 1749 if ((r = sshkey_load_public(options.host_cert_files[i], 1750 &key, NULL)) != 0) { 1751 error("Could not load host certificate \"%s\": %s", 1752 options.host_cert_files[i], ssh_err(r)); 1753 continue; 1754 } 1755 if (!sshkey_is_cert(key)) { 1756 error("Certificate file is not a certificate: %s", 1757 options.host_cert_files[i]); 1758 sshkey_free(key); 1759 continue; 1760 } 1761 /* Find matching private key */ 1762 for (j = 0; j < options.num_host_key_files; j++) { 1763 if (sshkey_equal_public(key, 1764 sensitive_data.host_keys[j])) { 1765 sensitive_data.host_certificates[j] = key; 1766 break; 1767 } 1768 } 1769 if (j >= options.num_host_key_files) { 1770 error("No matching private key for certificate: %s", 1771 options.host_cert_files[i]); 1772 sshkey_free(key); 1773 continue; 1774 } 1775 sensitive_data.host_certificates[j] = key; 1776 debug("host certificate: #%u type %d %s", j, key->type, 1777 sshkey_type(key)); 1778 } 1779 1780 if (use_privsep) { 1781 struct stat st; 1782 1783 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1784 fatal("Privilege separation user %s does not exist", 1785 SSH_PRIVSEP_USER); 1786 endpwent(); 1787 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1788 (S_ISDIR(st.st_mode) == 0)) 1789 fatal("Missing privilege separation directory: %s", 1790 _PATH_PRIVSEP_CHROOT_DIR); 1791 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1792 fatal("%s must be owned by root and not group or " 1793 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1794 } 1795 1796 if (test_flag > 1) { 1797 /* 1798 * If no connection info was provided by -C then use 1799 * use a blank one that will cause no predicate to match. 1800 */ 1801 if (connection_info == NULL) 1802 connection_info = get_connection_info(ssh, 0, 0); 1803 connection_info->test = 1; 1804 parse_server_match_config(&options, &includes, connection_info); 1805 dump_config(&options); 1806 } 1807 1808 /* Configuration looks good, so exit if in test mode. */ 1809 if (test_flag) 1810 exit(0); 1811 1812 if (rexec_flag) { 1813 if (rexec_argc < 0) 1814 fatal("rexec_argc %d < 0", rexec_argc); 1815 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1816 for (i = 0; i < (u_int)rexec_argc; i++) { 1817 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1818 rexec_argv[i] = saved_argv[i]; 1819 } 1820 rexec_argv[rexec_argc] = "-R"; 1821 rexec_argv[rexec_argc + 1] = NULL; 1822 } 1823 listener_proctitle = prepare_proctitle(ac, av); 1824 1825 /* Ensure that umask disallows at least group and world write */ 1826 new_umask = umask(0077) | 0022; 1827 (void) umask(new_umask); 1828 1829 /* Initialize the log (it is reinitialized below in case we forked). */ 1830 if (debug_flag && (!inetd_flag || rexeced_flag)) 1831 log_stderr = 1; 1832 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1833 1834 /* 1835 * If not in debugging mode, not started from inetd and not already 1836 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1837 * terminal, and fork. The original process exits. 1838 */ 1839 already_daemon = daemonized(); 1840 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1841 1842 if (daemon(0, 0) == -1) 1843 fatal("daemon() failed: %.200s", strerror(errno)); 1844 1845 disconnect_controlling_tty(); 1846 } 1847 /* Reinitialize the log (because of the fork above). */ 1848 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1849 1850 /* Chdir to the root directory so that the current disk can be 1851 unmounted if desired. */ 1852 if (chdir("/") == -1) 1853 error("chdir(\"/\"): %s", strerror(errno)); 1854 1855 /* ignore SIGPIPE */ 1856 ssh_signal(SIGPIPE, SIG_IGN); 1857 1858 /* Get a connection, either from inetd or a listening TCP socket */ 1859 if (inetd_flag) { 1860 server_accept_inetd(&sock_in, &sock_out); 1861 } else { 1862 server_listen(); 1863 1864 ssh_signal(SIGHUP, sighup_handler); 1865 ssh_signal(SIGCHLD, main_sigchld_handler); 1866 ssh_signal(SIGTERM, sigterm_handler); 1867 ssh_signal(SIGQUIT, sigterm_handler); 1868 1869 /* 1870 * Write out the pid file after the sigterm handler 1871 * is setup and the listen sockets are bound 1872 */ 1873 if (options.pid_file != NULL && !debug_flag) { 1874 FILE *f = fopen(options.pid_file, "w"); 1875 1876 if (f == NULL) { 1877 error("Couldn't create pid file \"%s\": %s", 1878 options.pid_file, strerror(errno)); 1879 } else { 1880 fprintf(f, "%ld\n", (long) getpid()); 1881 fclose(f); 1882 } 1883 } 1884 1885 /* Accept a connection and return in a forked child */ 1886 server_accept_loop(&sock_in, &sock_out, 1887 &newsock, config_s); 1888 } 1889 1890 /* This is the child processing a new connection. */ 1891 setproctitle("%s", "[accepted]"); 1892 1893 /* 1894 * Create a new session and process group since the 4.4BSD 1895 * setlogin() affects the entire process group. We don't 1896 * want the child to be able to affect the parent. 1897 */ 1898 if (!debug_flag && !inetd_flag && setsid() == -1) 1899 error("setsid: %.100s", strerror(errno)); 1900 1901 if (rexec_flag) { 1902 int fd; 1903 1904 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1905 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1906 dup2(newsock, STDIN_FILENO); 1907 dup2(STDIN_FILENO, STDOUT_FILENO); 1908 if (startup_pipe == -1) 1909 close(REEXEC_STARTUP_PIPE_FD); 1910 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1911 dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); 1912 close(startup_pipe); 1913 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1914 } 1915 1916 dup2(config_s[1], REEXEC_CONFIG_PASS_FD); 1917 close(config_s[1]); 1918 1919 execv(rexec_argv[0], rexec_argv); 1920 1921 /* Reexec has failed, fall back and continue */ 1922 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 1923 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 1924 log_init(__progname, options.log_level, 1925 options.log_facility, log_stderr); 1926 1927 /* Clean up fds */ 1928 close(REEXEC_CONFIG_PASS_FD); 1929 newsock = sock_out = sock_in = dup(STDIN_FILENO); 1930 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { 1931 dup2(fd, STDIN_FILENO); 1932 dup2(fd, STDOUT_FILENO); 1933 if (fd > STDERR_FILENO) 1934 close(fd); 1935 } 1936 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 1937 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1938 } 1939 1940 /* Executed child processes don't need these. */ 1941 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 1942 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 1943 1944 /* 1945 * Disable the key regeneration alarm. We will not regenerate the 1946 * key since we are no longer in a position to give it to anyone. We 1947 * will not restart on SIGHUP since it no longer makes sense. 1948 */ 1949 alarm(0); 1950 ssh_signal(SIGALRM, SIG_DFL); 1951 ssh_signal(SIGHUP, SIG_DFL); 1952 ssh_signal(SIGTERM, SIG_DFL); 1953 ssh_signal(SIGQUIT, SIG_DFL); 1954 ssh_signal(SIGCHLD, SIG_DFL); 1955 1956 /* 1957 * Register our connection. This turns encryption off because we do 1958 * not have a key. 1959 */ 1960 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 1961 fatal("Unable to create connection"); 1962 the_active_state = ssh; 1963 ssh_packet_set_server(ssh); 1964 1965 check_ip_options(ssh); 1966 1967 /* Prepare the channels layer */ 1968 channel_init_channels(ssh); 1969 channel_set_af(ssh, options.address_family); 1970 process_permitopen(ssh, &options); 1971 1972 /* Set SO_KEEPALIVE if requested. */ 1973 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 1974 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) 1975 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 1976 1977 if ((remote_port = ssh_remote_port(ssh)) < 0) { 1978 debug("ssh_remote_port failed"); 1979 cleanup_exit(255); 1980 } 1981 1982 /* 1983 * The rest of the code depends on the fact that 1984 * ssh_remote_ipaddr() caches the remote ip, even if 1985 * the socket goes away. 1986 */ 1987 remote_ip = ssh_remote_ipaddr(ssh); 1988 1989 rdomain = ssh_packet_rdomain_in(ssh); 1990 1991 /* Log the connection. */ 1992 laddr = get_local_ipaddr(sock_in); 1993 verbose("Connection from %s port %d on %s port %d%s%s%s", 1994 remote_ip, remote_port, laddr, ssh_local_port(ssh), 1995 rdomain == NULL ? "" : " rdomain \"", 1996 rdomain == NULL ? "" : rdomain, 1997 rdomain == NULL ? "" : "\""); 1998 free(laddr); 1999 2000 /* 2001 * We don't want to listen forever unless the other side 2002 * successfully authenticates itself. So we set up an alarm which is 2003 * cleared after successful authentication. A limit of zero 2004 * indicates no limit. Note that we don't set the alarm in debugging 2005 * mode; it is just annoying to have the server exit just when you 2006 * are about to discover the bug. 2007 */ 2008 ssh_signal(SIGALRM, grace_alarm_handler); 2009 if (!debug_flag) 2010 alarm(options.login_grace_time); 2011 2012 if (kex_exchange_identification(ssh, -1, options.version_addendum) != 0) 2013 cleanup_exit(255); /* error already logged */ 2014 2015 ssh_packet_set_nonblocking(ssh); 2016 2017 /* allocate authentication context */ 2018 authctxt = xcalloc(1, sizeof(*authctxt)); 2019 ssh->authctxt = authctxt; 2020 2021 /* XXX global for cleanup, access from other modules */ 2022 the_authctxt = authctxt; 2023 2024 /* Set default key authentication options */ 2025 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2026 fatal("allocation failed"); 2027 2028 /* prepare buffer to collect messages to display to user after login */ 2029 if ((loginmsg = sshbuf_new()) == NULL) 2030 fatal("%s: sshbuf_new failed", __func__); 2031 auth_debug_reset(); 2032 2033 if (use_privsep) { 2034 if (privsep_preauth(ssh) == 1) 2035 goto authenticated; 2036 } else if (have_agent) { 2037 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2038 error("Unable to get agent socket: %s", ssh_err(r)); 2039 have_agent = 0; 2040 } 2041 } 2042 2043 /* perform the key exchange */ 2044 /* authenticate user and start session */ 2045 do_ssh2_kex(ssh); 2046 do_authentication2(ssh); 2047 2048 /* 2049 * If we use privilege separation, the unprivileged child transfers 2050 * the current keystate and exits 2051 */ 2052 if (use_privsep) { 2053 mm_send_keystate(ssh, pmonitor); 2054 ssh_packet_clear_keys(ssh); 2055 exit(0); 2056 } 2057 2058 authenticated: 2059 /* 2060 * Cancel the alarm we set to limit the time taken for 2061 * authentication. 2062 */ 2063 alarm(0); 2064 ssh_signal(SIGALRM, SIG_DFL); 2065 authctxt->authenticated = 1; 2066 if (startup_pipe != -1) { 2067 close(startup_pipe); 2068 startup_pipe = -1; 2069 } 2070 2071 if (options.routing_domain != NULL) 2072 set_process_rdomain(ssh, options.routing_domain); 2073 2074 /* 2075 * In privilege separation, we fork another child and prepare 2076 * file descriptor passing. 2077 */ 2078 if (use_privsep) { 2079 privsep_postauth(ssh, authctxt); 2080 /* the monitor process [priv] will not return */ 2081 } 2082 2083 ssh_packet_set_timeout(ssh, options.client_alive_interval, 2084 options.client_alive_count_max); 2085 2086 /* Try to send all our hostkeys to the client */ 2087 notify_hostkeys(ssh); 2088 2089 /* Start session. */ 2090 do_authenticated(ssh, authctxt); 2091 2092 /* The connection has been terminated. */ 2093 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 2094 verbose("Transferred: sent %llu, received %llu bytes", 2095 (unsigned long long)obytes, (unsigned long long)ibytes); 2096 2097 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2098 ssh_packet_close(ssh); 2099 2100 if (use_privsep) 2101 mm_terminate(); 2102 2103 exit(0); 2104 } 2105 2106 int 2107 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 2108 struct sshkey *pubkey, u_char **signature, size_t *slenp, 2109 const u_char *data, size_t dlen, const char *alg) 2110 { 2111 int r; 2112 2113 if (use_privsep) { 2114 if (privkey) { 2115 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 2116 data, dlen, alg, options.sk_provider, 2117 ssh->compat) < 0) 2118 fatal("%s: privkey sign failed", __func__); 2119 } else { 2120 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 2121 data, dlen, alg, options.sk_provider, 2122 ssh->compat) < 0) 2123 fatal("%s: pubkey sign failed", __func__); 2124 } 2125 } else { 2126 if (privkey) { 2127 if (sshkey_sign(privkey, signature, slenp, data, dlen, 2128 alg, options.sk_provider, ssh->compat) < 0) 2129 fatal("%s: privkey sign failed", __func__); 2130 } else { 2131 if ((r = ssh_agent_sign(auth_sock, pubkey, 2132 signature, slenp, data, dlen, alg, 2133 ssh->compat)) != 0) { 2134 fatal("%s: agent sign failed: %s", 2135 __func__, ssh_err(r)); 2136 } 2137 } 2138 } 2139 return 0; 2140 } 2141 2142 /* SSH2 key exchange */ 2143 static void 2144 do_ssh2_kex(struct ssh *ssh) 2145 { 2146 char *myproposal[PROPOSAL_MAX] = { KEX_SERVER }; 2147 struct kex *kex; 2148 int r; 2149 2150 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal( 2151 options.kex_algorithms); 2152 myproposal[PROPOSAL_ENC_ALGS_CTOS] = compat_cipher_proposal( 2153 options.ciphers); 2154 myproposal[PROPOSAL_ENC_ALGS_STOC] = compat_cipher_proposal( 2155 options.ciphers); 2156 myproposal[PROPOSAL_MAC_ALGS_CTOS] = 2157 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; 2158 2159 if (options.compression == COMP_NONE) { 2160 myproposal[PROPOSAL_COMP_ALGS_CTOS] = 2161 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; 2162 } 2163 2164 if (options.rekey_limit || options.rekey_interval) 2165 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 2166 options.rekey_interval); 2167 2168 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = compat_pkalg_proposal( 2169 list_hostkey_types()); 2170 2171 /* start key exchange */ 2172 if ((r = kex_setup(ssh, myproposal)) != 0) 2173 fatal("kex_setup: %s", ssh_err(r)); 2174 kex = ssh->kex; 2175 #ifdef WITH_OPENSSL 2176 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 2177 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 2178 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 2179 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 2180 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 2181 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2182 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2183 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 2184 #endif 2185 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 2186 kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_server; 2187 kex->load_host_public_key=&get_hostkey_public_by_type; 2188 kex->load_host_private_key=&get_hostkey_private_by_type; 2189 kex->host_key_index=&get_hostkey_index; 2190 kex->sign = sshd_hostkey_sign; 2191 2192 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 2193 2194 session_id2 = kex->session_id; 2195 session_id2_len = kex->session_id_len; 2196 2197 #ifdef DEBUG_KEXDH 2198 /* send 1st encrypted/maced/compressed message */ 2199 packet_start(SSH2_MSG_IGNORE); 2200 packet_put_cstring("markus"); 2201 packet_send(); 2202 packet_write_wait(); 2203 #endif 2204 debug("KEX done"); 2205 } 2206 2207 /* server specific fatal cleanup */ 2208 void 2209 cleanup_exit(int i) 2210 { 2211 if (the_active_state != NULL && the_authctxt != NULL) { 2212 do_cleanup(the_active_state, the_authctxt); 2213 if (use_privsep && privsep_is_preauth && 2214 pmonitor != NULL && pmonitor->m_pid > 1) { 2215 debug("Killing privsep child %d", pmonitor->m_pid); 2216 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2217 errno != ESRCH) 2218 error("%s: kill(%d): %s", __func__, 2219 pmonitor->m_pid, strerror(errno)); 2220 } 2221 } 2222 _exit(i); 2223 } 2224