1 /* $OpenBSD: sshd.c,v 1.602 2024/01/08 00:34:34 djm Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * This program is the ssh daemon. It listens for connections from clients, 7 * and performs authentication, executes use commands or shell, and forwards 8 * information to/from the application to the user client over an encrypted 9 * connection. This can also handle forwarding of X11, TCP/IP, and 10 * authentication agent connections. 11 * 12 * As far as I am concerned, the code I have written for this software 13 * can be used freely for any purpose. Any derived versions of this 14 * software must be clearly marked as such, and if the derived work is 15 * incompatible with the protocol description in the RFC file, it must be 16 * called by a name other than "ssh" or "Secure Shell". 17 * 18 * SSH2 implementation: 19 * Privilege Separation: 20 * 21 * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. 22 * Copyright (c) 2002 Niels Provos. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 33 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 34 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 35 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 36 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 37 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 38 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 39 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 40 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 41 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 42 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 43 */ 44 45 #include <sys/types.h> 46 #include <sys/ioctl.h> 47 #include <sys/wait.h> 48 #include <sys/tree.h> 49 #include <sys/stat.h> 50 #include <sys/socket.h> 51 #include <sys/time.h> 52 #include <sys/queue.h> 53 54 #include <errno.h> 55 #include <fcntl.h> 56 #include <netdb.h> 57 #include <paths.h> 58 #include <poll.h> 59 #include <pwd.h> 60 #include <signal.h> 61 #include <stdio.h> 62 #include <stdlib.h> 63 #include <string.h> 64 #include <stdarg.h> 65 #include <unistd.h> 66 #include <limits.h> 67 68 #ifdef WITH_OPENSSL 69 #include <openssl/bn.h> 70 #endif 71 72 #include "xmalloc.h" 73 #include "ssh.h" 74 #include "ssh2.h" 75 #include "sshpty.h" 76 #include "packet.h" 77 #include "log.h" 78 #include "sshbuf.h" 79 #include "misc.h" 80 #include "match.h" 81 #include "servconf.h" 82 #include "uidswap.h" 83 #include "compat.h" 84 #include "cipher.h" 85 #include "digest.h" 86 #include "sshkey.h" 87 #include "kex.h" 88 #include "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 #include "srclimit.h" 110 #include "dh.h" 111 112 /* Re-exec fds */ 113 #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) 114 #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) 115 #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) 116 #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) 117 118 extern char *__progname; 119 120 /* Server configuration options. */ 121 ServerOptions options; 122 123 /* Name of the server configuration file. */ 124 char *config_file_name = _PATH_SERVER_CONFIG_FILE; 125 126 /* 127 * Debug mode flag. This can be set on the command line. If debug 128 * mode is enabled, extra debugging output will be sent to the system 129 * log, the daemon will not go to background, and will exit after processing 130 * the first connection. 131 */ 132 int debug_flag = 0; 133 134 /* 135 * Indicating that the daemon should only test the configuration and keys. 136 * If test_flag > 1 ("-T" flag), then sshd will also dump the effective 137 * configuration, optionally using connection information provided by the 138 * "-C" flag. 139 */ 140 static int test_flag = 0; 141 142 /* Flag indicating that the daemon is being started from inetd. */ 143 static int inetd_flag = 0; 144 145 /* Flag indicating that sshd should not detach and become a daemon. */ 146 static int no_daemon_flag = 0; 147 148 /* debug goes to stderr unless inetd_flag is set */ 149 static int log_stderr = 0; 150 151 /* Saved arguments to main(). */ 152 static char **saved_argv; 153 154 /* re-exec */ 155 static int rexeced_flag = 0; 156 static int rexec_flag = 1; 157 static int rexec_argc = 0; 158 static char **rexec_argv; 159 160 /* 161 * The sockets that the server is listening; this is used in the SIGHUP 162 * signal handler. 163 */ 164 #define MAX_LISTEN_SOCKS 16 165 static int listen_socks[MAX_LISTEN_SOCKS]; 166 static int num_listen_socks = 0; 167 168 /* Daemon's agent connection */ 169 int auth_sock = -1; 170 static int have_agent = 0; 171 172 /* 173 * Any really sensitive data in the application is contained in this 174 * structure. The idea is that this structure could be locked into memory so 175 * that the pages do not get written into swap. However, there are some 176 * problems. The private key contains BIGNUMs, and we do not (in principle) 177 * have access to the internals of them, and locking just the structure is 178 * not very useful. Currently, memory locking is not implemented. 179 */ 180 struct { 181 struct sshkey **host_keys; /* all private host keys */ 182 struct sshkey **host_pubkeys; /* all public host keys */ 183 struct sshkey **host_certificates; /* all public host certificates */ 184 int have_ssh2_key; 185 } sensitive_data; 186 187 /* This is set to true when a signal is received. */ 188 static volatile sig_atomic_t received_sighup = 0; 189 static volatile sig_atomic_t received_sigterm = 0; 190 191 /* record remote hostname or ip */ 192 u_int utmp_len = HOST_NAME_MAX+1; 193 194 /* 195 * startup_pipes/flags are used for tracking children of the listening sshd 196 * process early in their lifespans. This tracking is needed for three things: 197 * 198 * 1) Implementing the MaxStartups limit of concurrent unauthenticated 199 * connections. 200 * 2) Avoiding a race condition for SIGHUP processing, where child processes 201 * may have listen_socks open that could collide with main listener process 202 * after it restarts. 203 * 3) Ensuring that rexec'd sshd processes have received their initial state 204 * from the parent listen process before handling SIGHUP. 205 * 206 * Child processes signal that they have completed closure of the listen_socks 207 * and (if applicable) received their rexec state by sending a char over their 208 * sock. Child processes signal that authentication has completed by closing 209 * the sock (or by exiting). 210 */ 211 static int *startup_pipes = NULL; 212 static int *startup_flags = NULL; /* Indicates child closed listener */ 213 static int startup_pipe = -1; /* in child */ 214 215 /* variables used for privilege separation */ 216 int use_privsep = -1; 217 struct monitor *pmonitor = NULL; 218 int privsep_is_preauth = 1; 219 220 /* global connection state and authentication contexts */ 221 Authctxt *the_authctxt = NULL; 222 struct ssh *the_active_state; 223 224 /* global key/cert auth options. XXX move to permanent ssh->authctxt? */ 225 struct sshauthopt *auth_opts = NULL; 226 227 /* sshd_config buffer */ 228 struct sshbuf *cfg; 229 230 /* Included files from the configuration file */ 231 struct include_list includes = TAILQ_HEAD_INITIALIZER(includes); 232 233 /* message to be displayed after login */ 234 struct sshbuf *loginmsg; 235 236 /* Prototypes for various functions defined later in this file. */ 237 void destroy_sensitive_data(void); 238 void demote_sensitive_data(void); 239 static void do_ssh2_kex(struct ssh *); 240 241 static char *listener_proctitle; 242 243 /* 244 * Close all listening sockets 245 */ 246 static void 247 close_listen_socks(void) 248 { 249 int i; 250 251 for (i = 0; i < num_listen_socks; i++) 252 close(listen_socks[i]); 253 num_listen_socks = 0; 254 } 255 256 static void 257 close_startup_pipes(void) 258 { 259 int i; 260 261 if (startup_pipes) 262 for (i = 0; i < options.max_startups; i++) 263 if (startup_pipes[i] != -1) 264 close(startup_pipes[i]); 265 } 266 267 /* 268 * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; 269 * the effect is to reread the configuration file (and to regenerate 270 * the server key). 271 */ 272 273 static void 274 sighup_handler(int sig) 275 { 276 received_sighup = 1; 277 } 278 279 /* 280 * Called from the main program after receiving SIGHUP. 281 * Restarts the server. 282 */ 283 static void 284 sighup_restart(void) 285 { 286 logit("Received SIGHUP; restarting."); 287 if (options.pid_file != NULL) 288 unlink(options.pid_file); 289 close_listen_socks(); 290 close_startup_pipes(); 291 ssh_signal(SIGHUP, SIG_IGN); /* will be restored after exec */ 292 execv(saved_argv[0], saved_argv); 293 logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], 294 strerror(errno)); 295 exit(1); 296 } 297 298 /* 299 * Generic signal handler for terminating signals in the master daemon. 300 */ 301 static void 302 sigterm_handler(int sig) 303 { 304 received_sigterm = sig; 305 } 306 307 /* 308 * SIGCHLD handler. This is called whenever a child dies. This will then 309 * reap any zombies left by exited children. 310 */ 311 static void 312 main_sigchld_handler(int sig) 313 { 314 int save_errno = errno; 315 pid_t pid; 316 int status; 317 318 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || 319 (pid == -1 && errno == EINTR)) 320 ; 321 errno = save_errno; 322 } 323 324 /* 325 * Signal handler for the alarm after the login grace period has expired. 326 */ 327 static void 328 grace_alarm_handler(int sig) 329 { 330 /* 331 * Try to kill any processes that we have spawned, E.g. authorized 332 * keys command helpers or privsep children. 333 */ 334 if (getpgid(0) == getpid()) { 335 ssh_signal(SIGTERM, SIG_IGN); 336 kill(0, SIGTERM); 337 } 338 339 /* Log error and exit. */ 340 sigdie("Timeout before authentication for %s port %d", 341 ssh_remote_ipaddr(the_active_state), 342 ssh_remote_port(the_active_state)); 343 } 344 345 /* Destroy the host and server keys. They will no longer be needed. */ 346 void 347 destroy_sensitive_data(void) 348 { 349 u_int i; 350 351 for (i = 0; i < options.num_host_key_files; i++) { 352 if (sensitive_data.host_keys[i]) { 353 sshkey_free(sensitive_data.host_keys[i]); 354 sensitive_data.host_keys[i] = NULL; 355 } 356 if (sensitive_data.host_certificates[i]) { 357 sshkey_free(sensitive_data.host_certificates[i]); 358 sensitive_data.host_certificates[i] = NULL; 359 } 360 } 361 } 362 363 /* Demote private to public keys for network child */ 364 void 365 demote_sensitive_data(void) 366 { 367 struct sshkey *tmp; 368 u_int i; 369 int r; 370 371 for (i = 0; i < options.num_host_key_files; i++) { 372 if (sensitive_data.host_keys[i]) { 373 if ((r = sshkey_from_private( 374 sensitive_data.host_keys[i], &tmp)) != 0) 375 fatal_r(r, "could not demote host %s key", 376 sshkey_type(sensitive_data.host_keys[i])); 377 sshkey_free(sensitive_data.host_keys[i]); 378 sensitive_data.host_keys[i] = tmp; 379 } 380 /* Certs do not need demotion */ 381 } 382 } 383 384 static void 385 privsep_preauth_child(void) 386 { 387 gid_t gidset[1]; 388 struct passwd *pw; 389 390 /* Enable challenge-response authentication for privilege separation */ 391 privsep_challenge_enable(); 392 393 #ifdef GSSAPI 394 /* Cache supported mechanism OIDs for later use */ 395 ssh_gssapi_prepare_supported_oids(); 396 #endif 397 398 /* Demote the private keys to public keys. */ 399 demote_sensitive_data(); 400 401 /* Demote the child */ 402 if (getuid() == 0 || geteuid() == 0) { 403 if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) 404 fatal("Privilege separation user %s does not exist", 405 SSH_PRIVSEP_USER); 406 pw = pwcopy(pw); /* Ensure mutable */ 407 endpwent(); 408 freezero(pw->pw_passwd, strlen(pw->pw_passwd)); 409 410 /* Change our root directory */ 411 if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) 412 fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, 413 strerror(errno)); 414 if (chdir("/") == -1) 415 fatal("chdir(\"/\"): %s", strerror(errno)); 416 417 /* 418 * Drop our privileges 419 * NB. Can't use setusercontext() after chroot. 420 */ 421 debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, 422 (u_int)pw->pw_gid); 423 gidset[0] = pw->pw_gid; 424 if (setgroups(1, gidset) == -1) 425 fatal("setgroups: %.100s", strerror(errno)); 426 permanently_set_uid(pw); 427 } 428 } 429 430 static int 431 privsep_preauth(struct ssh *ssh) 432 { 433 int status, r; 434 pid_t pid; 435 struct ssh_sandbox *box = NULL; 436 437 /* Set up unprivileged child process to deal with network data */ 438 pmonitor = monitor_init(); 439 /* Store a pointer to the kex for later rekeying */ 440 pmonitor->m_pkex = &ssh->kex; 441 442 if (use_privsep == PRIVSEP_ON) 443 box = ssh_sandbox_init(); 444 pid = fork(); 445 if (pid == -1) { 446 fatal("fork of unprivileged child failed"); 447 } else if (pid != 0) { 448 debug2("Network child is on pid %ld", (long)pid); 449 450 pmonitor->m_pid = pid; 451 if (have_agent) { 452 r = ssh_get_authentication_socket(&auth_sock); 453 if (r != 0) { 454 error_r(r, "Could not get agent socket"); 455 have_agent = 0; 456 } 457 } 458 if (box != NULL) 459 ssh_sandbox_parent_preauth(box, pid); 460 monitor_child_preauth(ssh, pmonitor); 461 462 /* Wait for the child's exit status */ 463 while (waitpid(pid, &status, 0) == -1) { 464 if (errno == EINTR) 465 continue; 466 pmonitor->m_pid = -1; 467 fatal_f("waitpid: %s", strerror(errno)); 468 } 469 privsep_is_preauth = 0; 470 pmonitor->m_pid = -1; 471 if (WIFEXITED(status)) { 472 if (WEXITSTATUS(status) != 0) 473 fatal_f("preauth child exited with status %d", 474 WEXITSTATUS(status)); 475 } else if (WIFSIGNALED(status)) 476 fatal_f("preauth child terminated by signal %d", 477 WTERMSIG(status)); 478 if (box != NULL) 479 ssh_sandbox_parent_finish(box); 480 return 1; 481 } else { 482 /* child */ 483 close(pmonitor->m_sendfd); 484 close(pmonitor->m_log_recvfd); 485 486 /* Arrange for logging to be sent to the monitor */ 487 set_log_handler(mm_log_handler, pmonitor); 488 489 privsep_preauth_child(); 490 setproctitle("%s", "[net]"); 491 if (box != NULL) 492 ssh_sandbox_child(box); 493 494 return 0; 495 } 496 } 497 498 static void 499 privsep_postauth(struct ssh *ssh, Authctxt *authctxt) 500 { 501 if (authctxt->pw->pw_uid == 0) { 502 /* File descriptor passing is broken or root login */ 503 use_privsep = 0; 504 goto skip; 505 } 506 507 /* New socket pair */ 508 monitor_reinit(pmonitor); 509 510 pmonitor->m_pid = fork(); 511 if (pmonitor->m_pid == -1) 512 fatal("fork of unprivileged child failed"); 513 else if (pmonitor->m_pid != 0) { 514 verbose("User child is on pid %ld", (long)pmonitor->m_pid); 515 sshbuf_reset(loginmsg); 516 monitor_clear_keystate(ssh, pmonitor); 517 monitor_child_postauth(ssh, pmonitor); 518 519 /* NEVERREACHED */ 520 exit(0); 521 } 522 523 /* child */ 524 525 close(pmonitor->m_sendfd); 526 pmonitor->m_sendfd = -1; 527 528 /* Demote the private keys to public keys. */ 529 demote_sensitive_data(); 530 531 /* Drop privileges */ 532 do_setusercontext(authctxt->pw); 533 534 skip: 535 /* It is safe now to apply the key state */ 536 monitor_apply_keystate(ssh, pmonitor); 537 538 /* 539 * Tell the packet layer that authentication was successful, since 540 * this information is not part of the key state. 541 */ 542 ssh_packet_set_authenticated(ssh); 543 } 544 545 static void 546 append_hostkey_type(struct sshbuf *b, const char *s) 547 { 548 int r; 549 550 if (match_pattern_list(s, options.hostkeyalgorithms, 0) != 1) { 551 debug3_f("%s key not permitted by HostkeyAlgorithms", s); 552 return; 553 } 554 if ((r = sshbuf_putf(b, "%s%s", sshbuf_len(b) > 0 ? "," : "", s)) != 0) 555 fatal_fr(r, "sshbuf_putf"); 556 } 557 558 static char * 559 list_hostkey_types(void) 560 { 561 struct sshbuf *b; 562 struct sshkey *key; 563 char *ret; 564 u_int i; 565 566 if ((b = sshbuf_new()) == NULL) 567 fatal_f("sshbuf_new failed"); 568 for (i = 0; i < options.num_host_key_files; i++) { 569 key = sensitive_data.host_keys[i]; 570 if (key == NULL) 571 key = sensitive_data.host_pubkeys[i]; 572 if (key == NULL) 573 continue; 574 switch (key->type) { 575 case KEY_RSA: 576 /* for RSA we also support SHA2 signatures */ 577 append_hostkey_type(b, "rsa-sha2-512"); 578 append_hostkey_type(b, "rsa-sha2-256"); 579 /* FALLTHROUGH */ 580 case KEY_DSA: 581 case KEY_ECDSA: 582 case KEY_ED25519: 583 case KEY_ECDSA_SK: 584 case KEY_ED25519_SK: 585 case KEY_XMSS: 586 append_hostkey_type(b, sshkey_ssh_name(key)); 587 break; 588 } 589 /* If the private key has a cert peer, then list that too */ 590 key = sensitive_data.host_certificates[i]; 591 if (key == NULL) 592 continue; 593 switch (key->type) { 594 case KEY_RSA_CERT: 595 /* for RSA we also support SHA2 signatures */ 596 append_hostkey_type(b, 597 "rsa-sha2-512-cert-v01@openssh.com"); 598 append_hostkey_type(b, 599 "rsa-sha2-256-cert-v01@openssh.com"); 600 /* FALLTHROUGH */ 601 case KEY_DSA_CERT: 602 case KEY_ECDSA_CERT: 603 case KEY_ED25519_CERT: 604 case KEY_ECDSA_SK_CERT: 605 case KEY_ED25519_SK_CERT: 606 case KEY_XMSS_CERT: 607 append_hostkey_type(b, sshkey_ssh_name(key)); 608 break; 609 } 610 } 611 if ((ret = sshbuf_dup_string(b)) == NULL) 612 fatal_f("sshbuf_dup_string failed"); 613 sshbuf_free(b); 614 debug_f("%s", ret); 615 return ret; 616 } 617 618 static struct sshkey * 619 get_hostkey_by_type(int type, int nid, int need_private, struct ssh *ssh) 620 { 621 u_int i; 622 struct sshkey *key; 623 624 for (i = 0; i < options.num_host_key_files; i++) { 625 switch (type) { 626 case KEY_RSA_CERT: 627 case KEY_DSA_CERT: 628 case KEY_ECDSA_CERT: 629 case KEY_ED25519_CERT: 630 case KEY_ECDSA_SK_CERT: 631 case KEY_ED25519_SK_CERT: 632 case KEY_XMSS_CERT: 633 key = sensitive_data.host_certificates[i]; 634 break; 635 default: 636 key = sensitive_data.host_keys[i]; 637 if (key == NULL && !need_private) 638 key = sensitive_data.host_pubkeys[i]; 639 break; 640 } 641 if (key == NULL || key->type != type) 642 continue; 643 switch (type) { 644 case KEY_ECDSA: 645 case KEY_ECDSA_SK: 646 case KEY_ECDSA_CERT: 647 case KEY_ECDSA_SK_CERT: 648 if (key->ecdsa_nid != nid) 649 continue; 650 /* FALLTHROUGH */ 651 default: 652 return need_private ? 653 sensitive_data.host_keys[i] : key; 654 } 655 } 656 return NULL; 657 } 658 659 struct sshkey * 660 get_hostkey_public_by_type(int type, int nid, struct ssh *ssh) 661 { 662 return get_hostkey_by_type(type, nid, 0, ssh); 663 } 664 665 struct sshkey * 666 get_hostkey_private_by_type(int type, int nid, struct ssh *ssh) 667 { 668 return get_hostkey_by_type(type, nid, 1, ssh); 669 } 670 671 struct sshkey * 672 get_hostkey_by_index(int ind) 673 { 674 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 675 return (NULL); 676 return (sensitive_data.host_keys[ind]); 677 } 678 679 struct sshkey * 680 get_hostkey_public_by_index(int ind, struct ssh *ssh) 681 { 682 if (ind < 0 || (u_int)ind >= options.num_host_key_files) 683 return (NULL); 684 return (sensitive_data.host_pubkeys[ind]); 685 } 686 687 int 688 get_hostkey_index(struct sshkey *key, int compare, struct ssh *ssh) 689 { 690 u_int i; 691 692 for (i = 0; i < options.num_host_key_files; i++) { 693 if (sshkey_is_cert(key)) { 694 if (key == sensitive_data.host_certificates[i] || 695 (compare && sensitive_data.host_certificates[i] && 696 sshkey_equal(key, 697 sensitive_data.host_certificates[i]))) 698 return (i); 699 } else { 700 if (key == sensitive_data.host_keys[i] || 701 (compare && sensitive_data.host_keys[i] && 702 sshkey_equal(key, sensitive_data.host_keys[i]))) 703 return (i); 704 if (key == sensitive_data.host_pubkeys[i] || 705 (compare && sensitive_data.host_pubkeys[i] && 706 sshkey_equal(key, sensitive_data.host_pubkeys[i]))) 707 return (i); 708 } 709 } 710 return (-1); 711 } 712 713 /* Inform the client of all hostkeys */ 714 static void 715 notify_hostkeys(struct ssh *ssh) 716 { 717 struct sshbuf *buf; 718 struct sshkey *key; 719 u_int i, nkeys; 720 int r; 721 char *fp; 722 723 /* Some clients cannot cope with the hostkeys message, skip those. */ 724 if (ssh->compat & SSH_BUG_HOSTKEYS) 725 return; 726 727 if ((buf = sshbuf_new()) == NULL) 728 fatal_f("sshbuf_new"); 729 for (i = nkeys = 0; i < options.num_host_key_files; i++) { 730 key = get_hostkey_public_by_index(i, ssh); 731 if (key == NULL || key->type == KEY_UNSPEC || 732 sshkey_is_cert(key)) 733 continue; 734 fp = sshkey_fingerprint(key, options.fingerprint_hash, 735 SSH_FP_DEFAULT); 736 debug3_f("key %d: %s %s", i, sshkey_ssh_name(key), fp); 737 free(fp); 738 if (nkeys == 0) { 739 /* 740 * Start building the request when we find the 741 * first usable key. 742 */ 743 if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 || 744 (r = sshpkt_put_cstring(ssh, "hostkeys-00@openssh.com")) != 0 || 745 (r = sshpkt_put_u8(ssh, 0)) != 0) /* want reply */ 746 sshpkt_fatal(ssh, r, "%s: start request", __func__); 747 } 748 /* Append the key to the request */ 749 sshbuf_reset(buf); 750 if ((r = sshkey_putb(key, buf)) != 0) 751 fatal_fr(r, "couldn't put hostkey %d", i); 752 if ((r = sshpkt_put_stringb(ssh, buf)) != 0) 753 sshpkt_fatal(ssh, r, "%s: append key", __func__); 754 nkeys++; 755 } 756 debug3_f("sent %u hostkeys", nkeys); 757 if (nkeys == 0) 758 fatal_f("no hostkeys"); 759 if ((r = sshpkt_send(ssh)) != 0) 760 sshpkt_fatal(ssh, r, "%s: send", __func__); 761 sshbuf_free(buf); 762 } 763 764 /* 765 * returns 1 if connection should be dropped, 0 otherwise. 766 * dropping starts at connection #max_startups_begin with a probability 767 * of (max_startups_rate/100). the probability increases linearly until 768 * all connections are dropped for startups > max_startups 769 */ 770 static int 771 should_drop_connection(int startups) 772 { 773 int p, r; 774 775 if (startups < options.max_startups_begin) 776 return 0; 777 if (startups >= options.max_startups) 778 return 1; 779 if (options.max_startups_rate == 100) 780 return 1; 781 782 p = 100 - options.max_startups_rate; 783 p *= startups - options.max_startups_begin; 784 p /= options.max_startups - options.max_startups_begin; 785 p += options.max_startups_rate; 786 r = arc4random_uniform(100); 787 788 debug_f("p %d, r %d", p, r); 789 return (r < p) ? 1 : 0; 790 } 791 792 /* 793 * Check whether connection should be accepted by MaxStartups. 794 * Returns 0 if the connection is accepted. If the connection is refused, 795 * returns 1 and attempts to send notification to client. 796 * Logs when the MaxStartups condition is entered or exited, and periodically 797 * while in that state. 798 */ 799 static int 800 drop_connection(int sock, int startups, int notify_pipe) 801 { 802 char *laddr, *raddr; 803 const char msg[] = "Exceeded MaxStartups\r\n"; 804 static time_t last_drop, first_drop; 805 static u_int ndropped; 806 LogLevel drop_level = SYSLOG_LEVEL_VERBOSE; 807 time_t now; 808 809 now = monotime(); 810 if (!should_drop_connection(startups) && 811 srclimit_check_allow(sock, notify_pipe) == 1) { 812 if (last_drop != 0 && 813 startups < options.max_startups_begin - 1) { 814 /* XXX maybe need better hysteresis here */ 815 logit("exited MaxStartups throttling after %s, " 816 "%u connections dropped", 817 fmt_timeframe(now - first_drop), ndropped); 818 last_drop = 0; 819 } 820 return 0; 821 } 822 823 #define SSHD_MAXSTARTUPS_LOG_INTERVAL (5 * 60) 824 if (last_drop == 0) { 825 error("beginning MaxStartups throttling"); 826 drop_level = SYSLOG_LEVEL_INFO; 827 first_drop = now; 828 ndropped = 0; 829 } else if (last_drop + SSHD_MAXSTARTUPS_LOG_INTERVAL < now) { 830 /* Periodic logs */ 831 error("in MaxStartups throttling for %s, " 832 "%u connections dropped", 833 fmt_timeframe(now - first_drop), ndropped + 1); 834 drop_level = SYSLOG_LEVEL_INFO; 835 } 836 last_drop = now; 837 ndropped++; 838 839 laddr = get_local_ipaddr(sock); 840 raddr = get_peer_ipaddr(sock); 841 do_log2(drop_level, "drop connection #%d from [%s]:%d on [%s]:%d " 842 "past MaxStartups", startups, raddr, get_peer_port(sock), 843 laddr, get_local_port(sock)); 844 free(laddr); 845 free(raddr); 846 /* best-effort notification to client */ 847 (void)write(sock, msg, sizeof(msg) - 1); 848 return 1; 849 } 850 851 static void 852 usage(void) 853 { 854 fprintf(stderr, "%s, %s\n", SSH_VERSION, SSH_OPENSSL_VERSION); 855 fprintf(stderr, 856 "usage: sshd [-46DdeGiqTtV] [-C connection_spec] [-c host_cert_file]\n" 857 " [-E log_file] [-f config_file] [-g login_grace_time]\n" 858 " [-h host_key_file] [-o option] [-p port] [-u len]\n" 859 ); 860 exit(1); 861 } 862 863 static void 864 send_rexec_state(int fd, struct sshbuf *conf) 865 { 866 struct sshbuf *m = NULL, *inc = NULL; 867 struct include_item *item = NULL; 868 int r; 869 870 debug3_f("entering fd = %d config len %zu", fd, 871 sshbuf_len(conf)); 872 873 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 874 fatal_f("sshbuf_new failed"); 875 876 /* pack includes into a string */ 877 TAILQ_FOREACH(item, &includes, entry) { 878 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 879 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 880 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 881 fatal_fr(r, "compose includes"); 882 } 883 884 /* 885 * Protocol from reexec master to child: 886 * string configuration 887 * string included_files[] { 888 * string selector 889 * string filename 890 * string contents 891 * } 892 */ 893 if ((r = sshbuf_put_stringb(m, conf)) != 0 || 894 (r = sshbuf_put_stringb(m, inc)) != 0) 895 fatal_fr(r, "compose config"); 896 if (ssh_msg_send(fd, 0, m) == -1) 897 error_f("ssh_msg_send failed"); 898 899 sshbuf_free(m); 900 sshbuf_free(inc); 901 902 debug3_f("done"); 903 } 904 905 static void 906 recv_rexec_state(int fd, struct sshbuf *conf) 907 { 908 struct sshbuf *m, *inc; 909 u_char *cp, ver; 910 size_t len; 911 int r; 912 struct include_item *item; 913 914 debug3_f("entering fd = %d", fd); 915 916 if ((m = sshbuf_new()) == NULL || (inc = sshbuf_new()) == NULL) 917 fatal_f("sshbuf_new failed"); 918 if (ssh_msg_recv(fd, m) == -1) 919 fatal_f("ssh_msg_recv failed"); 920 if ((r = sshbuf_get_u8(m, &ver)) != 0) 921 fatal_fr(r, "parse version"); 922 if (ver != 0) 923 fatal_f("rexec version mismatch"); 924 if ((r = sshbuf_get_string(m, &cp, &len)) != 0 || 925 (r = sshbuf_get_stringb(m, inc)) != 0) 926 fatal_fr(r, "parse config"); 927 928 if (conf != NULL && (r = sshbuf_put(conf, cp, len))) 929 fatal_fr(r, "sshbuf_put"); 930 931 while (sshbuf_len(inc) != 0) { 932 item = xcalloc(1, sizeof(*item)); 933 if ((item->contents = sshbuf_new()) == NULL) 934 fatal_f("sshbuf_new failed"); 935 if ((r = sshbuf_get_cstring(inc, &item->selector, NULL)) != 0 || 936 (r = sshbuf_get_cstring(inc, &item->filename, NULL)) != 0 || 937 (r = sshbuf_get_stringb(inc, item->contents)) != 0) 938 fatal_fr(r, "parse includes"); 939 TAILQ_INSERT_TAIL(&includes, item, entry); 940 } 941 942 free(cp); 943 sshbuf_free(m); 944 945 debug3_f("done"); 946 } 947 948 /* Accept a connection from inetd */ 949 static void 950 server_accept_inetd(int *sock_in, int *sock_out) 951 { 952 if (rexeced_flag) { 953 close(REEXEC_CONFIG_PASS_FD); 954 *sock_in = *sock_out = dup(STDIN_FILENO); 955 } else { 956 *sock_in = dup(STDIN_FILENO); 957 *sock_out = dup(STDOUT_FILENO); 958 } 959 /* 960 * We intentionally do not close the descriptors 0, 1, and 2 961 * as our code for setting the descriptors won't work if 962 * ttyfd happens to be one of those. 963 */ 964 if (stdfd_devnull(1, 1, !log_stderr) == -1) 965 error_f("stdfd_devnull failed"); 966 debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); 967 } 968 969 /* 970 * Listen for TCP connections 971 */ 972 static void 973 listen_on_addrs(struct listenaddr *la) 974 { 975 int ret, listen_sock; 976 struct addrinfo *ai; 977 char ntop[NI_MAXHOST], strport[NI_MAXSERV]; 978 979 for (ai = la->addrs; ai; ai = ai->ai_next) { 980 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) 981 continue; 982 if (num_listen_socks >= MAX_LISTEN_SOCKS) 983 fatal("Too many listen sockets. " 984 "Enlarge MAX_LISTEN_SOCKS"); 985 if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, 986 ntop, sizeof(ntop), strport, sizeof(strport), 987 NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { 988 error("getnameinfo failed: %.100s", 989 ssh_gai_strerror(ret)); 990 continue; 991 } 992 /* Create socket for listening. */ 993 listen_sock = socket(ai->ai_family, ai->ai_socktype, 994 ai->ai_protocol); 995 if (listen_sock == -1) { 996 /* kernel may not support ipv6 */ 997 verbose("socket: %.100s", strerror(errno)); 998 continue; 999 } 1000 if (set_nonblock(listen_sock) == -1) { 1001 close(listen_sock); 1002 continue; 1003 } 1004 if (fcntl(listen_sock, F_SETFD, FD_CLOEXEC) == -1) { 1005 verbose("socket: CLOEXEC: %s", strerror(errno)); 1006 close(listen_sock); 1007 continue; 1008 } 1009 /* Socket options */ 1010 set_reuseaddr(listen_sock); 1011 if (la->rdomain != NULL && 1012 set_rdomain(listen_sock, la->rdomain) == -1) { 1013 close(listen_sock); 1014 continue; 1015 } 1016 1017 debug("Bind to port %s on %s.", strport, ntop); 1018 1019 /* Bind the socket to the desired port. */ 1020 if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) == -1) { 1021 error("Bind to port %s on %s failed: %.200s.", 1022 strport, ntop, strerror(errno)); 1023 close(listen_sock); 1024 continue; 1025 } 1026 listen_socks[num_listen_socks] = listen_sock; 1027 num_listen_socks++; 1028 1029 /* Start listening on the port. */ 1030 if (listen(listen_sock, SSH_LISTEN_BACKLOG) == -1) 1031 fatal("listen on [%s]:%s: %.100s", 1032 ntop, strport, strerror(errno)); 1033 logit("Server listening on %s port %s%s%s.", 1034 ntop, strport, 1035 la->rdomain == NULL ? "" : " rdomain ", 1036 la->rdomain == NULL ? "" : la->rdomain); 1037 } 1038 } 1039 1040 static void 1041 server_listen(void) 1042 { 1043 u_int i; 1044 1045 /* Initialise per-source limit tracking. */ 1046 srclimit_init(options.max_startups, options.per_source_max_startups, 1047 options.per_source_masklen_ipv4, options.per_source_masklen_ipv6); 1048 1049 for (i = 0; i < options.num_listen_addrs; i++) { 1050 listen_on_addrs(&options.listen_addrs[i]); 1051 freeaddrinfo(options.listen_addrs[i].addrs); 1052 free(options.listen_addrs[i].rdomain); 1053 memset(&options.listen_addrs[i], 0, 1054 sizeof(options.listen_addrs[i])); 1055 } 1056 free(options.listen_addrs); 1057 options.listen_addrs = NULL; 1058 options.num_listen_addrs = 0; 1059 1060 if (!num_listen_socks) 1061 fatal("Cannot bind any address."); 1062 } 1063 1064 /* 1065 * The main TCP accept loop. Note that, for the non-debug case, returns 1066 * from this function are in a forked subprocess. 1067 */ 1068 static void 1069 server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) 1070 { 1071 struct pollfd *pfd = NULL; 1072 int i, j, ret, npfd; 1073 int ostartups = -1, startups = 0, listening = 0, lameduck = 0; 1074 int startup_p[2] = { -1 , -1 }, *startup_pollfd; 1075 char c = 0; 1076 struct sockaddr_storage from; 1077 socklen_t fromlen; 1078 pid_t pid; 1079 sigset_t nsigset, osigset; 1080 1081 /* setup fd set for accept */ 1082 /* pipes connected to unauthenticated child sshd processes */ 1083 startup_pipes = xcalloc(options.max_startups, sizeof(int)); 1084 startup_flags = xcalloc(options.max_startups, sizeof(int)); 1085 startup_pollfd = xcalloc(options.max_startups, sizeof(int)); 1086 for (i = 0; i < options.max_startups; i++) 1087 startup_pipes[i] = -1; 1088 1089 /* 1090 * Prepare signal mask that we use to block signals that might set 1091 * received_sigterm or received_sighup, so that we are guaranteed 1092 * to immediately wake up the ppoll if a signal is received after 1093 * the flag is checked. 1094 */ 1095 sigemptyset(&nsigset); 1096 sigaddset(&nsigset, SIGHUP); 1097 sigaddset(&nsigset, SIGCHLD); 1098 sigaddset(&nsigset, SIGTERM); 1099 sigaddset(&nsigset, SIGQUIT); 1100 1101 /* sized for worst-case */ 1102 pfd = xcalloc(num_listen_socks + options.max_startups, 1103 sizeof(struct pollfd)); 1104 1105 /* 1106 * Stay listening for connections until the system crashes or 1107 * the daemon is killed with a signal. 1108 */ 1109 for (;;) { 1110 sigprocmask(SIG_BLOCK, &nsigset, &osigset); 1111 if (received_sigterm) { 1112 logit("Received signal %d; terminating.", 1113 (int) received_sigterm); 1114 close_listen_socks(); 1115 if (options.pid_file != NULL) 1116 unlink(options.pid_file); 1117 exit(received_sigterm == SIGTERM ? 0 : 255); 1118 } 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 sigprocmask(SIG_SETMASK, &osigset, NULL); 1133 sighup_restart(); 1134 } 1135 } 1136 1137 for (i = 0; i < num_listen_socks; i++) { 1138 pfd[i].fd = listen_socks[i]; 1139 pfd[i].events = POLLIN; 1140 } 1141 npfd = num_listen_socks; 1142 for (i = 0; i < options.max_startups; i++) { 1143 startup_pollfd[i] = -1; 1144 if (startup_pipes[i] != -1) { 1145 pfd[npfd].fd = startup_pipes[i]; 1146 pfd[npfd].events = POLLIN; 1147 startup_pollfd[i] = npfd++; 1148 } 1149 } 1150 1151 /* Wait until a connection arrives or a child exits. */ 1152 ret = ppoll(pfd, npfd, NULL, &osigset); 1153 if (ret == -1 && errno != EINTR) { 1154 error("ppoll: %.100s", strerror(errno)); 1155 if (errno == EINVAL) 1156 cleanup_exit(1); /* can't recover */ 1157 } 1158 sigprocmask(SIG_SETMASK, &osigset, NULL); 1159 if (ret == -1) 1160 continue; 1161 1162 for (i = 0; i < options.max_startups; i++) { 1163 if (startup_pipes[i] == -1 || 1164 startup_pollfd[i] == -1 || 1165 !(pfd[startup_pollfd[i]].revents & (POLLIN|POLLHUP))) 1166 continue; 1167 switch (read(startup_pipes[i], &c, sizeof(c))) { 1168 case -1: 1169 if (errno == EINTR || errno == EAGAIN) 1170 continue; 1171 if (errno != EPIPE) { 1172 error_f("startup pipe %d (fd=%d): " 1173 "read %s", i, startup_pipes[i], 1174 strerror(errno)); 1175 } 1176 /* FALLTHROUGH */ 1177 case 0: 1178 /* child exited or completed auth */ 1179 close(startup_pipes[i]); 1180 srclimit_done(startup_pipes[i]); 1181 startup_pipes[i] = -1; 1182 startups--; 1183 if (startup_flags[i]) 1184 listening--; 1185 break; 1186 case 1: 1187 /* child has finished preliminaries */ 1188 if (startup_flags[i]) { 1189 listening--; 1190 startup_flags[i] = 0; 1191 } 1192 break; 1193 } 1194 } 1195 for (i = 0; i < num_listen_socks; i++) { 1196 if (!(pfd[i].revents & POLLIN)) 1197 continue; 1198 fromlen = sizeof(from); 1199 *newsock = accept(listen_socks[i], 1200 (struct sockaddr *)&from, &fromlen); 1201 if (*newsock == -1) { 1202 if (errno != EINTR && errno != EWOULDBLOCK && 1203 errno != ECONNABORTED) 1204 error("accept: %.100s", 1205 strerror(errno)); 1206 if (errno == EMFILE || errno == ENFILE) 1207 usleep(100 * 1000); 1208 continue; 1209 } 1210 if (unset_nonblock(*newsock) == -1) { 1211 close(*newsock); 1212 continue; 1213 } 1214 if (pipe(startup_p) == -1) { 1215 error_f("pipe(startup_p): %s", strerror(errno)); 1216 close(*newsock); 1217 continue; 1218 } 1219 if (drop_connection(*newsock, startups, startup_p[0])) { 1220 close(*newsock); 1221 close(startup_p[0]); 1222 close(startup_p[1]); 1223 continue; 1224 } 1225 1226 if (rexec_flag && socketpair(AF_UNIX, 1227 SOCK_STREAM, 0, config_s) == -1) { 1228 error("reexec socketpair: %s", 1229 strerror(errno)); 1230 close(*newsock); 1231 close(startup_p[0]); 1232 close(startup_p[1]); 1233 continue; 1234 } 1235 1236 for (j = 0; j < options.max_startups; j++) 1237 if (startup_pipes[j] == -1) { 1238 startup_pipes[j] = startup_p[0]; 1239 startups++; 1240 startup_flags[j] = 1; 1241 break; 1242 } 1243 1244 /* 1245 * Got connection. Fork a child to handle it, unless 1246 * we are in debugging mode. 1247 */ 1248 if (debug_flag) { 1249 /* 1250 * In debugging mode. Close the listening 1251 * socket, and start processing the 1252 * connection without forking. 1253 */ 1254 debug("Server will not fork when running in debugging mode."); 1255 close_listen_socks(); 1256 *sock_in = *newsock; 1257 *sock_out = *newsock; 1258 close(startup_p[0]); 1259 close(startup_p[1]); 1260 startup_pipe = -1; 1261 pid = getpid(); 1262 if (rexec_flag) { 1263 send_rexec_state(config_s[0], cfg); 1264 close(config_s[0]); 1265 } 1266 free(pfd); 1267 return; 1268 } 1269 1270 /* 1271 * Normal production daemon. Fork, and have 1272 * the child process the connection. The 1273 * parent continues listening. 1274 */ 1275 listening++; 1276 if ((pid = fork()) == 0) { 1277 /* 1278 * Child. Close the listening and 1279 * max_startup sockets. Start using 1280 * the accepted socket. Reinitialize 1281 * logging (since our pid has changed). 1282 * We return from this function to handle 1283 * the connection. 1284 */ 1285 startup_pipe = startup_p[1]; 1286 close_startup_pipes(); 1287 close_listen_socks(); 1288 *sock_in = *newsock; 1289 *sock_out = *newsock; 1290 log_init(__progname, 1291 options.log_level, 1292 options.log_facility, 1293 log_stderr); 1294 if (rexec_flag) 1295 close(config_s[0]); 1296 else { 1297 /* 1298 * Signal parent that the preliminaries 1299 * for this child are complete. For the 1300 * re-exec case, this happens after the 1301 * child has received the rexec state 1302 * from the server. 1303 */ 1304 (void)atomicio(vwrite, startup_pipe, 1305 "\0", 1); 1306 } 1307 free(pfd); 1308 return; 1309 } 1310 1311 /* Parent. Stay in the loop. */ 1312 if (pid == -1) 1313 error("fork: %.100s", strerror(errno)); 1314 else 1315 debug("Forked child %ld.", (long)pid); 1316 1317 close(startup_p[1]); 1318 1319 if (rexec_flag) { 1320 close(config_s[1]); 1321 send_rexec_state(config_s[0], cfg); 1322 close(config_s[0]); 1323 } 1324 close(*newsock); 1325 } 1326 } 1327 } 1328 1329 /* 1330 * If IP options are supported, make sure there are none (log and 1331 * return an error if any are found). Basically we are worried about 1332 * source routing; it can be used to pretend you are somebody 1333 * (ip-address) you are not. That itself may be "almost acceptable" 1334 * under certain circumstances, but rhosts authentication is useless 1335 * if source routing is accepted. Notice also that if we just dropped 1336 * source routing here, the other side could use IP spoofing to do 1337 * rest of the interaction and could still bypass security. So we 1338 * exit here if we detect any IP options. 1339 */ 1340 static void 1341 check_ip_options(struct ssh *ssh) 1342 { 1343 int sock_in = ssh_packet_get_connection_in(ssh); 1344 struct sockaddr_storage from; 1345 u_char opts[200]; 1346 socklen_t i, option_size = sizeof(opts), fromlen = sizeof(from); 1347 char text[sizeof(opts) * 3 + 1]; 1348 1349 memset(&from, 0, sizeof(from)); 1350 if (getpeername(sock_in, (struct sockaddr *)&from, 1351 &fromlen) == -1) 1352 return; 1353 if (from.ss_family != AF_INET) 1354 return; 1355 /* XXX IPv6 options? */ 1356 1357 if (getsockopt(sock_in, IPPROTO_IP, IP_OPTIONS, opts, 1358 &option_size) >= 0 && option_size != 0) { 1359 text[0] = '\0'; 1360 for (i = 0; i < option_size; i++) 1361 snprintf(text + i*3, sizeof(text) - i*3, 1362 " %2.2x", opts[i]); 1363 fatal("Connection from %.100s port %d with IP opts: %.800s", 1364 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), text); 1365 } 1366 return; 1367 } 1368 1369 /* Set the routing domain for this process */ 1370 static void 1371 set_process_rdomain(struct ssh *ssh, const char *name) 1372 { 1373 int rtable, ortable = getrtable(); 1374 const char *errstr; 1375 1376 if (name == NULL) 1377 return; /* default */ 1378 1379 if (strcmp(name, "%D") == 0) { 1380 /* "expands" to routing domain of connection */ 1381 if ((name = ssh_packet_rdomain_in(ssh)) == NULL) 1382 return; 1383 } 1384 1385 rtable = (int)strtonum(name, 0, 255, &errstr); 1386 if (errstr != NULL) /* Shouldn't happen */ 1387 fatal("Invalid routing domain \"%s\": %s", name, errstr); 1388 if (rtable != ortable && setrtable(rtable) != 0) 1389 fatal("Unable to set routing domain %d: %s", 1390 rtable, strerror(errno)); 1391 debug_f("set routing domain %d (was %d)", rtable, ortable); 1392 } 1393 1394 static void 1395 accumulate_host_timing_secret(struct sshbuf *server_cfg, 1396 struct sshkey *key) 1397 { 1398 static struct ssh_digest_ctx *ctx; 1399 u_char *hash; 1400 size_t len; 1401 struct sshbuf *buf; 1402 int r; 1403 1404 if (ctx == NULL && (ctx = ssh_digest_start(SSH_DIGEST_SHA512)) == NULL) 1405 fatal_f("ssh_digest_start"); 1406 if (key == NULL) { /* finalize */ 1407 /* add server config in case we are using agent for host keys */ 1408 if (ssh_digest_update(ctx, sshbuf_ptr(server_cfg), 1409 sshbuf_len(server_cfg)) != 0) 1410 fatal_f("ssh_digest_update"); 1411 len = ssh_digest_bytes(SSH_DIGEST_SHA512); 1412 hash = xmalloc(len); 1413 if (ssh_digest_final(ctx, hash, len) != 0) 1414 fatal_f("ssh_digest_final"); 1415 options.timing_secret = PEEK_U64(hash); 1416 freezero(hash, len); 1417 ssh_digest_free(ctx); 1418 ctx = NULL; 1419 return; 1420 } 1421 if ((buf = sshbuf_new()) == NULL) 1422 fatal_f("could not allocate buffer"); 1423 if ((r = sshkey_private_serialize(key, buf)) != 0) 1424 fatal_fr(r, "encode %s key", sshkey_ssh_name(key)); 1425 if (ssh_digest_update(ctx, sshbuf_ptr(buf), sshbuf_len(buf)) != 0) 1426 fatal_f("ssh_digest_update"); 1427 sshbuf_reset(buf); 1428 sshbuf_free(buf); 1429 } 1430 1431 static char * 1432 prepare_proctitle(int ac, char **av) 1433 { 1434 char *ret = NULL; 1435 int i; 1436 1437 for (i = 0; i < ac; i++) 1438 xextendf(&ret, " ", "%s", av[i]); 1439 return ret; 1440 } 1441 1442 static void 1443 print_config(struct ssh *ssh, struct connection_info *connection_info) 1444 { 1445 /* 1446 * If no connection info was provided by -C then use 1447 * use a blank one that will cause no predicate to match. 1448 */ 1449 if (connection_info == NULL) 1450 connection_info = get_connection_info(ssh, 0, 0); 1451 connection_info->test = 1; 1452 parse_server_match_config(&options, &includes, connection_info); 1453 dump_config(&options); 1454 exit(0); 1455 } 1456 1457 /* 1458 * Main program for the daemon. 1459 */ 1460 int 1461 main(int ac, char **av) 1462 { 1463 struct ssh *ssh = NULL; 1464 extern char *optarg; 1465 extern int optind; 1466 int r, opt, on = 1, do_dump_cfg = 0, already_daemon, remote_port; 1467 int sock_in = -1, sock_out = -1, newsock = -1; 1468 const char *remote_ip, *rdomain; 1469 char *fp, *line, *laddr, *logfile = NULL; 1470 int config_s[2] = { -1 , -1 }; 1471 u_int i, j; 1472 u_int64_t ibytes, obytes; 1473 mode_t new_umask; 1474 struct sshkey *key; 1475 struct sshkey *pubkey; 1476 int keytype; 1477 Authctxt *authctxt; 1478 struct connection_info *connection_info = NULL; 1479 sigset_t sigmask; 1480 1481 sigemptyset(&sigmask); 1482 sigprocmask(SIG_SETMASK, &sigmask, NULL); 1483 1484 /* Save argv. */ 1485 saved_argv = av; 1486 rexec_argc = ac; 1487 1488 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ 1489 sanitise_stdfd(); 1490 1491 /* Initialize configuration options to their default values. */ 1492 initialize_server_options(&options); 1493 1494 /* Parse command-line arguments. */ 1495 while ((opt = getopt(ac, av, 1496 "C:E:b:c:f:g:h:k:o:p:u:46DGQRTdeiqrtV")) != -1) { 1497 switch (opt) { 1498 case '4': 1499 options.address_family = AF_INET; 1500 break; 1501 case '6': 1502 options.address_family = AF_INET6; 1503 break; 1504 case 'f': 1505 config_file_name = optarg; 1506 break; 1507 case 'c': 1508 servconf_add_hostcert("[command-line]", 0, 1509 &options, optarg); 1510 break; 1511 case 'd': 1512 if (debug_flag == 0) { 1513 debug_flag = 1; 1514 options.log_level = SYSLOG_LEVEL_DEBUG1; 1515 } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) 1516 options.log_level++; 1517 break; 1518 case 'D': 1519 no_daemon_flag = 1; 1520 break; 1521 case 'G': 1522 do_dump_cfg = 1; 1523 break; 1524 case 'E': 1525 logfile = optarg; 1526 /* FALLTHROUGH */ 1527 case 'e': 1528 log_stderr = 1; 1529 break; 1530 case 'i': 1531 inetd_flag = 1; 1532 break; 1533 case 'r': 1534 rexec_flag = 0; 1535 break; 1536 case 'R': 1537 rexeced_flag = 1; 1538 inetd_flag = 1; 1539 break; 1540 case 'Q': 1541 /* ignored */ 1542 break; 1543 case 'q': 1544 options.log_level = SYSLOG_LEVEL_QUIET; 1545 break; 1546 case 'b': 1547 /* protocol 1, ignored */ 1548 break; 1549 case 'p': 1550 options.ports_from_cmdline = 1; 1551 if (options.num_ports >= MAX_PORTS) { 1552 fprintf(stderr, "too many ports.\n"); 1553 exit(1); 1554 } 1555 options.ports[options.num_ports++] = a2port(optarg); 1556 if (options.ports[options.num_ports-1] <= 0) { 1557 fprintf(stderr, "Bad port number.\n"); 1558 exit(1); 1559 } 1560 break; 1561 case 'g': 1562 if ((options.login_grace_time = convtime(optarg)) == -1) { 1563 fprintf(stderr, "Invalid login grace time.\n"); 1564 exit(1); 1565 } 1566 break; 1567 case 'k': 1568 /* protocol 1, ignored */ 1569 break; 1570 case 'h': 1571 servconf_add_hostkey("[command-line]", 0, 1572 &options, optarg, 1); 1573 break; 1574 case 't': 1575 test_flag = 1; 1576 break; 1577 case 'T': 1578 test_flag = 2; 1579 break; 1580 case 'C': 1581 connection_info = get_connection_info(ssh, 0, 0); 1582 if (parse_server_match_testspec(connection_info, 1583 optarg) == -1) 1584 exit(1); 1585 break; 1586 case 'u': 1587 utmp_len = (u_int)strtonum(optarg, 0, HOST_NAME_MAX+1+1, NULL); 1588 if (utmp_len > HOST_NAME_MAX+1) { 1589 fprintf(stderr, "Invalid utmp length.\n"); 1590 exit(1); 1591 } 1592 break; 1593 case 'o': 1594 line = xstrdup(optarg); 1595 if (process_server_config_line(&options, line, 1596 "command-line", 0, NULL, NULL, &includes) != 0) 1597 exit(1); 1598 free(line); 1599 break; 1600 case 'V': 1601 fprintf(stderr, "%s, %s\n", 1602 SSH_VERSION, SSH_OPENSSL_VERSION); 1603 exit(0); 1604 default: 1605 usage(); 1606 break; 1607 } 1608 } 1609 if (rexeced_flag || inetd_flag) 1610 rexec_flag = 0; 1611 if (!test_flag && !do_dump_cfg && rexec_flag && !path_absolute(av[0])) 1612 fatal("sshd re-exec requires execution with an absolute path"); 1613 if (rexeced_flag) 1614 closefrom(REEXEC_MIN_FREE_FD); 1615 else 1616 closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); 1617 1618 #ifdef WITH_OPENSSL 1619 OpenSSL_add_all_algorithms(); 1620 #endif 1621 1622 /* If requested, redirect the logs to the specified logfile. */ 1623 if (logfile != NULL) 1624 log_redirect_stderr_to(logfile); 1625 /* 1626 * Force logging to stderr until we have loaded the private host 1627 * key (unless started from inetd) 1628 */ 1629 log_init(__progname, 1630 options.log_level == SYSLOG_LEVEL_NOT_SET ? 1631 SYSLOG_LEVEL_INFO : options.log_level, 1632 options.log_facility == SYSLOG_FACILITY_NOT_SET ? 1633 SYSLOG_FACILITY_AUTH : options.log_facility, 1634 log_stderr || !inetd_flag || debug_flag); 1635 1636 sensitive_data.have_ssh2_key = 0; 1637 1638 /* 1639 * If we're not doing an extended test do not silently ignore connection 1640 * test params. 1641 */ 1642 if (test_flag < 2 && connection_info != NULL) 1643 fatal("Config test connection parameter (-C) provided without " 1644 "test mode (-T)"); 1645 1646 /* Fetch our configuration */ 1647 if ((cfg = sshbuf_new()) == NULL) 1648 fatal_f("sshbuf_new failed"); 1649 if (rexeced_flag) { 1650 setproctitle("%s", "[rexeced]"); 1651 recv_rexec_state(REEXEC_CONFIG_PASS_FD, cfg); 1652 if (!debug_flag) { 1653 startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); 1654 close(REEXEC_STARTUP_PIPE_FD); 1655 /* 1656 * Signal parent that this child is at a point where 1657 * they can go away if they have a SIGHUP pending. 1658 */ 1659 (void)atomicio(vwrite, startup_pipe, "\0", 1); 1660 } 1661 } else if (strcasecmp(config_file_name, "none") != 0) 1662 load_server_config(config_file_name, cfg); 1663 1664 parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, 1665 cfg, &includes, NULL, rexeced_flag); 1666 1667 #ifdef WITH_OPENSSL 1668 if (options.moduli_file != NULL) 1669 dh_set_moduli_file(options.moduli_file); 1670 #endif 1671 1672 /* Fill in default values for those options not explicitly set. */ 1673 fill_default_server_options(&options); 1674 1675 /* Check that options are sensible */ 1676 if (options.authorized_keys_command_user == NULL && 1677 (options.authorized_keys_command != NULL && 1678 strcasecmp(options.authorized_keys_command, "none") != 0)) 1679 fatal("AuthorizedKeysCommand set without " 1680 "AuthorizedKeysCommandUser"); 1681 if (options.authorized_principals_command_user == NULL && 1682 (options.authorized_principals_command != NULL && 1683 strcasecmp(options.authorized_principals_command, "none") != 0)) 1684 fatal("AuthorizedPrincipalsCommand set without " 1685 "AuthorizedPrincipalsCommandUser"); 1686 1687 /* 1688 * Check whether there is any path through configured auth methods. 1689 * Unfortunately it is not possible to verify this generally before 1690 * daemonisation in the presence of Match block, but this catches 1691 * and warns for trivial misconfigurations that could break login. 1692 */ 1693 if (options.num_auth_methods != 0) { 1694 for (i = 0; i < options.num_auth_methods; i++) { 1695 if (auth2_methods_valid(options.auth_methods[i], 1696 1) == 0) 1697 break; 1698 } 1699 if (i >= options.num_auth_methods) 1700 fatal("AuthenticationMethods cannot be satisfied by " 1701 "enabled authentication methods"); 1702 } 1703 1704 /* Check that there are no remaining arguments. */ 1705 if (optind < ac) { 1706 fprintf(stderr, "Extra argument %s.\n", av[optind]); 1707 exit(1); 1708 } 1709 1710 debug("sshd version %s, %s", SSH_VERSION, SSH_OPENSSL_VERSION); 1711 1712 if (do_dump_cfg) 1713 print_config(ssh, connection_info); 1714 1715 /* load host keys */ 1716 sensitive_data.host_keys = xcalloc(options.num_host_key_files, 1717 sizeof(struct sshkey *)); 1718 sensitive_data.host_pubkeys = xcalloc(options.num_host_key_files, 1719 sizeof(struct sshkey *)); 1720 1721 if (options.host_key_agent) { 1722 if (strcmp(options.host_key_agent, SSH_AUTHSOCKET_ENV_NAME)) 1723 setenv(SSH_AUTHSOCKET_ENV_NAME, 1724 options.host_key_agent, 1); 1725 if ((r = ssh_get_authentication_socket(NULL)) == 0) 1726 have_agent = 1; 1727 else 1728 error_r(r, "Could not connect to agent \"%s\"", 1729 options.host_key_agent); 1730 } 1731 1732 for (i = 0; i < options.num_host_key_files; i++) { 1733 int ll = options.host_key_file_userprovided[i] ? 1734 SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_DEBUG1; 1735 1736 if (options.host_key_files[i] == NULL) 1737 continue; 1738 if ((r = sshkey_load_private(options.host_key_files[i], "", 1739 &key, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1740 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1741 options.host_key_files[i]); 1742 if (sshkey_is_sk(key) && 1743 key->sk_flags & SSH_SK_USER_PRESENCE_REQD) { 1744 debug("host key %s requires user presence, ignoring", 1745 options.host_key_files[i]); 1746 key->sk_flags &= ~SSH_SK_USER_PRESENCE_REQD; 1747 } 1748 if (r == 0 && key != NULL && 1749 (r = sshkey_shield_private(key)) != 0) { 1750 do_log2_r(r, ll, "Unable to shield host key \"%s\"", 1751 options.host_key_files[i]); 1752 sshkey_free(key); 1753 key = NULL; 1754 } 1755 if ((r = sshkey_load_public(options.host_key_files[i], 1756 &pubkey, NULL)) != 0 && r != SSH_ERR_SYSTEM_ERROR) 1757 do_log2_r(r, ll, "Unable to load host key \"%s\"", 1758 options.host_key_files[i]); 1759 if (pubkey != NULL && key != NULL) { 1760 if (!sshkey_equal(pubkey, key)) { 1761 error("Public key for %s does not match " 1762 "private key", options.host_key_files[i]); 1763 sshkey_free(pubkey); 1764 pubkey = NULL; 1765 } 1766 } 1767 if (pubkey == NULL && key != NULL) { 1768 if ((r = sshkey_from_private(key, &pubkey)) != 0) 1769 fatal_r(r, "Could not demote key: \"%s\"", 1770 options.host_key_files[i]); 1771 } 1772 if (pubkey != NULL && (r = sshkey_check_rsa_length(pubkey, 1773 options.required_rsa_size)) != 0) { 1774 error_fr(r, "Host key %s", options.host_key_files[i]); 1775 sshkey_free(pubkey); 1776 sshkey_free(key); 1777 continue; 1778 } 1779 sensitive_data.host_keys[i] = key; 1780 sensitive_data.host_pubkeys[i] = pubkey; 1781 1782 if (key == NULL && pubkey != NULL && have_agent) { 1783 debug("will rely on agent for hostkey %s", 1784 options.host_key_files[i]); 1785 keytype = pubkey->type; 1786 } else if (key != NULL) { 1787 keytype = key->type; 1788 accumulate_host_timing_secret(cfg, key); 1789 } else { 1790 do_log2(ll, "Unable to load host key: %s", 1791 options.host_key_files[i]); 1792 sensitive_data.host_keys[i] = NULL; 1793 sensitive_data.host_pubkeys[i] = NULL; 1794 continue; 1795 } 1796 1797 switch (keytype) { 1798 case KEY_RSA: 1799 case KEY_DSA: 1800 case KEY_ECDSA: 1801 case KEY_ED25519: 1802 case KEY_ECDSA_SK: 1803 case KEY_ED25519_SK: 1804 case KEY_XMSS: 1805 if (have_agent || key != NULL) 1806 sensitive_data.have_ssh2_key = 1; 1807 break; 1808 } 1809 if ((fp = sshkey_fingerprint(pubkey, options.fingerprint_hash, 1810 SSH_FP_DEFAULT)) == NULL) 1811 fatal("sshkey_fingerprint failed"); 1812 debug("%s host key #%d: %s %s", 1813 key ? "private" : "agent", i, sshkey_ssh_name(pubkey), fp); 1814 free(fp); 1815 } 1816 accumulate_host_timing_secret(cfg, NULL); 1817 if (!sensitive_data.have_ssh2_key) { 1818 logit("sshd: no hostkeys available -- exiting."); 1819 exit(1); 1820 } 1821 1822 /* 1823 * Load certificates. They are stored in an array at identical 1824 * indices to the public keys that they relate to. 1825 */ 1826 sensitive_data.host_certificates = xcalloc(options.num_host_key_files, 1827 sizeof(struct sshkey *)); 1828 for (i = 0; i < options.num_host_key_files; i++) 1829 sensitive_data.host_certificates[i] = NULL; 1830 1831 for (i = 0; i < options.num_host_cert_files; i++) { 1832 if (options.host_cert_files[i] == NULL) 1833 continue; 1834 if ((r = sshkey_load_public(options.host_cert_files[i], 1835 &key, NULL)) != 0) { 1836 error_r(r, "Could not load host certificate \"%s\"", 1837 options.host_cert_files[i]); 1838 continue; 1839 } 1840 if (!sshkey_is_cert(key)) { 1841 error("Certificate file is not a certificate: %s", 1842 options.host_cert_files[i]); 1843 sshkey_free(key); 1844 continue; 1845 } 1846 /* Find matching private key */ 1847 for (j = 0; j < options.num_host_key_files; j++) { 1848 if (sshkey_equal_public(key, 1849 sensitive_data.host_pubkeys[j])) { 1850 sensitive_data.host_certificates[j] = key; 1851 break; 1852 } 1853 } 1854 if (j >= options.num_host_key_files) { 1855 error("No matching private key for certificate: %s", 1856 options.host_cert_files[i]); 1857 sshkey_free(key); 1858 continue; 1859 } 1860 sensitive_data.host_certificates[j] = key; 1861 debug("host certificate: #%u type %d %s", j, key->type, 1862 sshkey_type(key)); 1863 } 1864 1865 if (use_privsep) { 1866 struct stat st; 1867 1868 if (getpwnam(SSH_PRIVSEP_USER) == NULL) 1869 fatal("Privilege separation user %s does not exist", 1870 SSH_PRIVSEP_USER); 1871 endpwent(); 1872 if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || 1873 (S_ISDIR(st.st_mode) == 0)) 1874 fatal("Missing privilege separation directory: %s", 1875 _PATH_PRIVSEP_CHROOT_DIR); 1876 if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) 1877 fatal("%s must be owned by root and not group or " 1878 "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); 1879 } 1880 1881 if (test_flag > 1) 1882 print_config(ssh, connection_info); 1883 1884 /* Configuration looks good, so exit if in test mode. */ 1885 if (test_flag) 1886 exit(0); 1887 1888 if (rexec_flag) { 1889 if (rexec_argc < 0) 1890 fatal("rexec_argc %d < 0", rexec_argc); 1891 rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); 1892 for (i = 0; i < (u_int)rexec_argc; i++) { 1893 debug("rexec_argv[%d]='%s'", i, saved_argv[i]); 1894 rexec_argv[i] = saved_argv[i]; 1895 } 1896 rexec_argv[rexec_argc] = "-R"; 1897 rexec_argv[rexec_argc + 1] = NULL; 1898 } 1899 listener_proctitle = prepare_proctitle(ac, av); 1900 1901 /* Ensure that umask disallows at least group and world write */ 1902 new_umask = umask(0077) | 0022; 1903 (void) umask(new_umask); 1904 1905 /* Initialize the log (it is reinitialized below in case we forked). */ 1906 if (debug_flag && (!inetd_flag || rexeced_flag)) 1907 log_stderr = 1; 1908 log_init(__progname, options.log_level, 1909 options.log_facility, log_stderr); 1910 for (i = 0; i < options.num_log_verbose; i++) 1911 log_verbose_add(options.log_verbose[i]); 1912 1913 /* 1914 * If not in debugging mode, not started from inetd and not already 1915 * daemonized (eg re-exec via SIGHUP), disconnect from the controlling 1916 * terminal, and fork. The original process exits. 1917 */ 1918 already_daemon = daemonized(); 1919 if (!(debug_flag || inetd_flag || no_daemon_flag || already_daemon)) { 1920 1921 if (daemon(0, 0) == -1) 1922 fatal("daemon() failed: %.200s", strerror(errno)); 1923 1924 disconnect_controlling_tty(); 1925 } 1926 /* Reinitialize the log (because of the fork above). */ 1927 log_init(__progname, options.log_level, options.log_facility, log_stderr); 1928 1929 /* 1930 * Chdir to the root directory so that the current disk can be 1931 * unmounted if desired. 1932 */ 1933 if (chdir("/") == -1) 1934 error("chdir(\"/\"): %s", strerror(errno)); 1935 1936 /* ignore SIGPIPE */ 1937 ssh_signal(SIGPIPE, SIG_IGN); 1938 1939 /* Get a connection, either from inetd or a listening TCP socket */ 1940 if (inetd_flag) { 1941 server_accept_inetd(&sock_in, &sock_out); 1942 } else { 1943 server_listen(); 1944 1945 ssh_signal(SIGHUP, sighup_handler); 1946 ssh_signal(SIGCHLD, main_sigchld_handler); 1947 ssh_signal(SIGTERM, sigterm_handler); 1948 ssh_signal(SIGQUIT, sigterm_handler); 1949 1950 /* 1951 * Write out the pid file after the sigterm handler 1952 * is setup and the listen sockets are bound 1953 */ 1954 if (options.pid_file != NULL && !debug_flag) { 1955 FILE *f = fopen(options.pid_file, "w"); 1956 1957 if (f == NULL) { 1958 error("Couldn't create pid file \"%s\": %s", 1959 options.pid_file, strerror(errno)); 1960 } else { 1961 fprintf(f, "%ld\n", (long) getpid()); 1962 fclose(f); 1963 } 1964 } 1965 1966 /* Accept a connection and return in a forked child */ 1967 server_accept_loop(&sock_in, &sock_out, 1968 &newsock, config_s); 1969 } 1970 1971 /* This is the child processing a new connection. */ 1972 setproctitle("%s", "[accepted]"); 1973 1974 /* 1975 * Create a new session and process group since the 4.4BSD 1976 * setlogin() affects the entire process group. We don't 1977 * want the child to be able to affect the parent. 1978 */ 1979 if (!debug_flag && !inetd_flag && setsid() == -1) 1980 error("setsid: %.100s", strerror(errno)); 1981 1982 if (rexec_flag) { 1983 debug("rexec start in %d out %d newsock %d pipe %d sock %d", 1984 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 1985 if (dup2(newsock, STDIN_FILENO) == -1) 1986 debug3_f("dup2 stdin: %s", strerror(errno)); 1987 if (dup2(STDIN_FILENO, STDOUT_FILENO) == -1) 1988 debug3_f("dup2 stdout: %s", strerror(errno)); 1989 if (startup_pipe == -1) 1990 close(REEXEC_STARTUP_PIPE_FD); 1991 else if (startup_pipe != REEXEC_STARTUP_PIPE_FD) { 1992 if (dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD) == -1) 1993 debug3_f("dup2 startup_p: %s", strerror(errno)); 1994 close(startup_pipe); 1995 startup_pipe = REEXEC_STARTUP_PIPE_FD; 1996 } 1997 1998 if (dup2(config_s[1], REEXEC_CONFIG_PASS_FD) == -1) 1999 debug3_f("dup2 config_s: %s", strerror(errno)); 2000 close(config_s[1]); 2001 2002 ssh_signal(SIGHUP, SIG_IGN); /* avoid reset to SIG_DFL */ 2003 execv(rexec_argv[0], rexec_argv); 2004 2005 /* Reexec has failed, fall back and continue */ 2006 error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); 2007 recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); 2008 log_init(__progname, options.log_level, 2009 options.log_facility, log_stderr); 2010 2011 /* Clean up fds */ 2012 close(REEXEC_CONFIG_PASS_FD); 2013 newsock = sock_out = sock_in = dup(STDIN_FILENO); 2014 if (stdfd_devnull(1, 1, 0) == -1) 2015 error_f("stdfd_devnull failed"); 2016 debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", 2017 sock_in, sock_out, newsock, startup_pipe, config_s[0]); 2018 } 2019 2020 /* Executed child processes don't need these. */ 2021 fcntl(sock_out, F_SETFD, FD_CLOEXEC); 2022 fcntl(sock_in, F_SETFD, FD_CLOEXEC); 2023 2024 /* We will not restart on SIGHUP since it no longer makes sense. */ 2025 ssh_signal(SIGALRM, SIG_DFL); 2026 ssh_signal(SIGHUP, SIG_DFL); 2027 ssh_signal(SIGTERM, SIG_DFL); 2028 ssh_signal(SIGQUIT, SIG_DFL); 2029 ssh_signal(SIGCHLD, SIG_DFL); 2030 2031 /* 2032 * Register our connection. This turns encryption off because we do 2033 * not have a key. 2034 */ 2035 if ((ssh = ssh_packet_set_connection(NULL, sock_in, sock_out)) == NULL) 2036 fatal("Unable to create connection"); 2037 the_active_state = ssh; 2038 ssh_packet_set_server(ssh); 2039 2040 check_ip_options(ssh); 2041 2042 /* Prepare the channels layer */ 2043 channel_init_channels(ssh); 2044 channel_set_af(ssh, options.address_family); 2045 process_channel_timeouts(ssh, &options); 2046 process_permitopen(ssh, &options); 2047 2048 /* Set SO_KEEPALIVE if requested. */ 2049 if (options.tcp_keep_alive && ssh_packet_connection_is_on_socket(ssh) && 2050 setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) == -1) 2051 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); 2052 2053 if ((remote_port = ssh_remote_port(ssh)) < 0) { 2054 debug("ssh_remote_port failed"); 2055 cleanup_exit(255); 2056 } 2057 2058 /* 2059 * The rest of the code depends on the fact that 2060 * ssh_remote_ipaddr() caches the remote ip, even if 2061 * the socket goes away. 2062 */ 2063 remote_ip = ssh_remote_ipaddr(ssh); 2064 2065 rdomain = ssh_packet_rdomain_in(ssh); 2066 2067 /* Log the connection. */ 2068 laddr = get_local_ipaddr(sock_in); 2069 verbose("Connection from %s port %d on %s port %d%s%s%s", 2070 remote_ip, remote_port, laddr, ssh_local_port(ssh), 2071 rdomain == NULL ? "" : " rdomain \"", 2072 rdomain == NULL ? "" : rdomain, 2073 rdomain == NULL ? "" : "\""); 2074 free(laddr); 2075 2076 /* 2077 * We don't want to listen forever unless the other side 2078 * successfully authenticates itself. So we set up an alarm which is 2079 * cleared after successful authentication. A limit of zero 2080 * indicates no limit. Note that we don't set the alarm in debugging 2081 * mode; it is just annoying to have the server exit just when you 2082 * are about to discover the bug. 2083 */ 2084 ssh_signal(SIGALRM, grace_alarm_handler); 2085 if (!debug_flag) 2086 alarm(options.login_grace_time); 2087 2088 if ((r = kex_exchange_identification(ssh, -1, 2089 options.version_addendum)) != 0) 2090 sshpkt_fatal(ssh, r, "banner exchange"); 2091 2092 ssh_packet_set_nonblocking(ssh); 2093 2094 /* allocate authentication context */ 2095 authctxt = xcalloc(1, sizeof(*authctxt)); 2096 ssh->authctxt = authctxt; 2097 2098 /* XXX global for cleanup, access from other modules */ 2099 the_authctxt = authctxt; 2100 2101 /* Set default key authentication options */ 2102 if ((auth_opts = sshauthopt_new_with_keys_defaults()) == NULL) 2103 fatal("allocation failed"); 2104 2105 /* prepare buffer to collect messages to display to user after login */ 2106 if ((loginmsg = sshbuf_new()) == NULL) 2107 fatal_f("sshbuf_new failed"); 2108 auth_debug_reset(); 2109 2110 if (use_privsep) { 2111 if (privsep_preauth(ssh) == 1) 2112 goto authenticated; 2113 } else if (have_agent) { 2114 if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) { 2115 error_r(r, "Unable to get agent socket"); 2116 have_agent = 0; 2117 } 2118 } 2119 2120 /* perform the key exchange */ 2121 /* authenticate user and start session */ 2122 do_ssh2_kex(ssh); 2123 do_authentication2(ssh); 2124 2125 /* 2126 * If we use privilege separation, the unprivileged child transfers 2127 * the current keystate and exits 2128 */ 2129 if (use_privsep) { 2130 mm_send_keystate(ssh, pmonitor); 2131 ssh_packet_clear_keys(ssh); 2132 exit(0); 2133 } 2134 2135 authenticated: 2136 /* 2137 * Cancel the alarm we set to limit the time taken for 2138 * authentication. 2139 */ 2140 alarm(0); 2141 ssh_signal(SIGALRM, SIG_DFL); 2142 authctxt->authenticated = 1; 2143 if (startup_pipe != -1) { 2144 close(startup_pipe); 2145 startup_pipe = -1; 2146 } 2147 2148 if (options.routing_domain != NULL) 2149 set_process_rdomain(ssh, options.routing_domain); 2150 2151 /* 2152 * In privilege separation, we fork another child and prepare 2153 * file descriptor passing. 2154 */ 2155 if (use_privsep) { 2156 privsep_postauth(ssh, authctxt); 2157 /* the monitor process [priv] will not return */ 2158 } 2159 2160 ssh_packet_set_timeout(ssh, options.client_alive_interval, 2161 options.client_alive_count_max); 2162 2163 /* Try to send all our hostkeys to the client */ 2164 notify_hostkeys(ssh); 2165 2166 /* Start session. */ 2167 do_authenticated(ssh, authctxt); 2168 2169 /* The connection has been terminated. */ 2170 ssh_packet_get_bytes(ssh, &ibytes, &obytes); 2171 verbose("Transferred: sent %llu, received %llu bytes", 2172 (unsigned long long)obytes, (unsigned long long)ibytes); 2173 2174 verbose("Closing connection to %.500s port %d", remote_ip, remote_port); 2175 ssh_packet_close(ssh); 2176 2177 if (use_privsep) 2178 mm_terminate(); 2179 2180 exit(0); 2181 } 2182 2183 int 2184 sshd_hostkey_sign(struct ssh *ssh, struct sshkey *privkey, 2185 struct sshkey *pubkey, u_char **signature, size_t *slenp, 2186 const u_char *data, size_t dlen, const char *alg) 2187 { 2188 int r; 2189 2190 if (use_privsep) { 2191 if (privkey) { 2192 if (mm_sshkey_sign(ssh, privkey, signature, slenp, 2193 data, dlen, alg, options.sk_provider, NULL, 2194 ssh->compat) < 0) 2195 fatal_f("privkey sign failed"); 2196 } else { 2197 if (mm_sshkey_sign(ssh, pubkey, signature, slenp, 2198 data, dlen, alg, options.sk_provider, NULL, 2199 ssh->compat) < 0) 2200 fatal_f("pubkey sign failed"); 2201 } 2202 } else { 2203 if (privkey) { 2204 if (sshkey_sign(privkey, signature, slenp, data, dlen, 2205 alg, options.sk_provider, NULL, ssh->compat) < 0) 2206 fatal_f("privkey sign failed"); 2207 } else { 2208 if ((r = ssh_agent_sign(auth_sock, pubkey, 2209 signature, slenp, data, dlen, alg, 2210 ssh->compat)) != 0) { 2211 fatal_fr(r, "agent sign failed"); 2212 } 2213 } 2214 } 2215 return 0; 2216 } 2217 2218 /* SSH2 key exchange */ 2219 static void 2220 do_ssh2_kex(struct ssh *ssh) 2221 { 2222 char *hkalgs = NULL, *myproposal[PROPOSAL_MAX]; 2223 const char *compression = NULL; 2224 struct kex *kex; 2225 int r; 2226 2227 if (options.rekey_limit || options.rekey_interval) 2228 ssh_packet_set_rekey_limits(ssh, options.rekey_limit, 2229 options.rekey_interval); 2230 2231 if (options.compression == COMP_NONE) 2232 compression = "none"; 2233 hkalgs = list_hostkey_types(); 2234 2235 kex_proposal_populate_entries(ssh, myproposal, options.kex_algorithms, 2236 options.ciphers, options.macs, compression, hkalgs); 2237 2238 free(hkalgs); 2239 2240 /* start key exchange */ 2241 if ((r = kex_setup(ssh, myproposal)) != 0) 2242 fatal_r(r, "kex_setup"); 2243 kex_set_server_sig_algs(ssh, options.pubkey_accepted_algos); 2244 kex = ssh->kex; 2245 2246 #ifdef WITH_OPENSSL 2247 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 2248 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 2249 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 2250 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 2251 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 2252 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 2253 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 2254 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 2255 #endif 2256 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 2257 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; 2258 kex->load_host_public_key=&get_hostkey_public_by_type; 2259 kex->load_host_private_key=&get_hostkey_private_by_type; 2260 kex->host_key_index=&get_hostkey_index; 2261 kex->sign = sshd_hostkey_sign; 2262 2263 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &kex->done); 2264 kex_proposal_free_entries(myproposal); 2265 2266 #ifdef DEBUG_KEXDH 2267 /* send 1st encrypted/maced/compressed message */ 2268 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 || 2269 (r = sshpkt_put_cstring(ssh, "markus")) != 0 || 2270 (r = sshpkt_send(ssh)) != 0 || 2271 (r = ssh_packet_write_wait(ssh)) != 0) 2272 fatal_fr(r, "send test"); 2273 #endif 2274 debug("KEX done"); 2275 } 2276 2277 /* server specific fatal cleanup */ 2278 void 2279 cleanup_exit(int i) 2280 { 2281 if (the_active_state != NULL && the_authctxt != NULL) { 2282 do_cleanup(the_active_state, the_authctxt); 2283 if (use_privsep && privsep_is_preauth && 2284 pmonitor != NULL && pmonitor->m_pid > 1) { 2285 debug("Killing privsep child %d", pmonitor->m_pid); 2286 if (kill(pmonitor->m_pid, SIGKILL) != 0 && 2287 errno != ESRCH) { 2288 error_f("kill(%d): %s", pmonitor->m_pid, 2289 strerror(errno)); 2290 } 2291 } 2292 } 2293 _exit(i); 2294 } 2295